2001 Kluwer Academic Publishers. Printed in the Netherlands.

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世界上茶和咖啡-消费的模式【外文翻译】

世界上茶和咖啡-消费的模式【外⽂翻译】外⽂翻译原⽂The worlds of tea and coffee: Patterns of consumption Material Source: 2003 Kluwer Academic Publishers. Author: David grigg AbstractCoffee and tea are both drunk in most countries, but typically one predominates. Coffee is the preferred drink in European the Americas, tea elsewhere. Until the early eighteenth century coffee production and consumption was confined to the Islamic world, tea production to East Asia. European traders altered this pattern dramatically. The present pattern of coffee consumption is influenced by income per capita,that of tea is not. Religious influences played some part in the early development of both tea and coffee but have little relevance at the present. National factors have influenced wider patterns. British preference for tea was taken to all their colonies. In recent years fears about health have had some influence on coffee consumption.IntroductionGeographers have always been interested in the production of food on the farm, but recently there has been a growing interest in aspects of food beyond the farm gate such as food processing, food security, restaurants and food health (Atkins and Bowler, 2001; Bell and Valentine, 1997).However, somewhat surprisingly the geography of food consumption–who eats what, where and why –has been an interest of only a few geographers and economists (Cépède and Lengelle, 1961; Grigg, 1995; Simoons, 1990; Bennett,1954; Kariel, 1966). But if little attention has been paid to international and regional variations in food consumption, the geography of drink attracts even less. Granted the production of wine has its students (Unwin, 1991; Blij, 1984) but alcoholic beverages are not the major drinks in most countries. In Europe coffee is generally the leading drink–excluding water –except in Britain and Ireland where it is tea ( P.V.G.D,1998.). Tea and coffee compete with each other in many countries, a topic investigated by N. Berdichevsky (1976),when however there was little data available on consumption in much of Africa and Asia, and Berdichevsky excluded producer countries from his study. TheFood and Agriculture Organization of the United Nations subsequently published data on food consumption, and it is now available for most member states from 1961 to 1996 (FAO, 2001). It seems worthwhile, now world-wide statistics are available, to reexamine the geography of tea and coffee consumption.The nature of tea and coffeeTea is a drink made by pouring hot water on the dried leaves of the tea plant, camellia sinensis. Coffee is prepared in a similar way, with hot water and the seeds of the coffee tree, of which coffea arabica and coffea canephoria var. robusta are the most used. The flesh of the cherries is removed, and the seeds roasted. The two drinks have a number of properties in common. The aroma and taste of both is pleasant although some find them bitter, especially coffee, unless milk and sugar are added. Hot drinks not only warm the body, but assuage hunger, at least temporarily; more important, prior to the advent of safe public water supplies, the boiling of water reduces the harmful bacteria carried in many water sources. Neither drink has any major nutritional value; a cup of tea contains only four calories, but forty if milk and sugar are added (Encyclopaedia Britannica, 1985a,p. 735).Far more important however is that both contain caffeine which stimulates the central nervous system, reduces sleepiness and increases vigilance; it is this that explains the popularity of both drinks. When they were first introduced into Europe in the seventeenth century the only alternative drinks, other than the frequently polluted water supplies, were the alcoholic beverages, which were also free of bacterial contamination. Tea and coffee were thus a valuable alternative to wine, beer or spirits and much beloved by temperance campaigners. In the twentieth century other non-alcoholic drinks have become widely available, such as mineral waters, soft drinks and juices, and have competed with both tea and coffee. In the United States for example, the consumption of soft drinks exceeds that of tea, coffeeand alcoholic beverages combined (P.V.G.D., 1998).World Patterns of consumption per capitaPredominates in North Africa, and is the preferred drink in much of the rest of Africa, although the amount drunk there is very small. There are distinct outliers of tea drinking in the British Isles, in South Africa, Argentina, Chile, and New Zealand (and Australia until recently). Coffee is the favoured drink only in Europe and the Americas. Not surprisingly, the per capita distribution of tea and coffee consumption largely replicates the map of preferences. Coffee consumption is highest in North America and Europe, but hardly drunk at all in the former Soviet Union, Africa orAsia, except in Japan, the Philippines, Israel and South Korea (Figure 3). However it is notable that whilst coffee is the preferred beverage in most of Latin America, where much of the production takes place, per capita consumption is below thatin Western Europe and North America. Tea consumption per capita is at its highest in south west and south Asia and North Africa, Russia and also in the British Isles, South Africa, Australia and New Zealand. Tea is little drunk in most of the Americas, tropical Africa or in Europe (Figure 4).Economic factorsThere is a marked difference between the influence of income per capita upon coffee and upon tea. The consumption of coffee per capita for all countries has been regressed upon GDP per capita which has been logarithmically transformed. There is a high correlation (r = 0.72) between income and consumption, and income accounts for half the variation in consumption (r2 = 0.52)(Figure 5). As noted earlier the highest consumption is in Western Europe and North America, the lowest in Africa and Asia, with most of the countries in Latin America falling between the two, as they do in incomes (Figure 3). In contrast tea shows very little correlation (Figure 6) between income and consumption (r = 0.17) nor does income help account for variations in consumption (r2 = 0.03). This is explained by the fact that coffee is the preferred drink in the richer countries, in North America and Europe, and tea drinking is the preferred drink in the poorer countries of Asia and Africa. However if the regression analysis is confined to only those countries where tea is the preferred drink, and those where coffee consumption per capita exceeds tea are excluded, then there is a much higher correlation (r = 0.65) between tea and income, and income is a more powerful determinant (r2 = 0.4) of variations. It is debatable what conclusions can be drawn from this evidence. Income is clearly important in determining in which countries there are the highest levels of consumption of the more expensive beverage, coffee; but this does not preclude the possibility of people in rich countries that can afford coffee, choosing to drink the cheaper beverage, tea. Cultural factorsIn 1900 even the United States, where coffee consumption had run well ahead of tea, still had a tea consumption much the same as Russia, where far more tea than coffee was drunk. In all the English- speaking countries, except the United States, more cups of tea were drunk than cups of coffee; tea was imported mainly from the British dominions in South Asia. However in the twentieth century the allegiance to tea has weakened (Table 6); the consumption of tea has declined in the English speaking countries except surprisingly in the United States, and coffee consumption has increased everywhere but the United States and South Africa; more cups of coffee than tea are now drunk in the United States, Canada and Australia; only New Zealand, the United Kingdom and South Africa remain faithful to tea (FAO, 2001) and only in South Africa is a greater quantity of tea than coffee consumed (Table 6). There are three possible reasons for the decline of tea and the increase of coffee. First is the changing nature of immigration. Since 1945 migration from Britain and Ireland has been a falling proportion of all migrants to Australia, New Zealand and Canada, reducing the proportion from tea drinking countries. Second, and a more likely explanation, has been the rising incomes in all these countries. It has been noted that in Britain since 1950 tea has behaved like an inferior good; as long as incomes were low the cheaper beverage was preferred, but as incomes have risen so coffee consumption has increased, and tea consumption has fallen (Ritson,1994). Much the same is true of the other English–speaking countries other than the United States. In the latter, concerns about the effect of caffeine on health may help explain the fall of coffee drinking, although the competition from soft drinks may be an equally powerful factor. A third possible reason may be the revival of the coffee house, which was an important factor in the early spread of coffee in the Middle East and in Western Europe in the eighteenth century. In Britain coffee houses had a temporary revival in the 1950s with the introduction from Italy of the expresso machine; more potent has been the rise of the Starbucks coffee chain in the United States and its spread to Britain. Coffee and tea have become associated with different lifestyles, tea being drunk at home by the old, coffee by the young and outgoing.ConclusionsIt is not possible to give a simple explanation of the world pattern of consumption of tea and coffee. It can be shown how the location of production and consumption of both tea and coffee has changed over time. Thus coffee drinking was once confined to the Middle East, then spread to Western Europe and later North America, and when production shifted to Latin America so consumption increased there. But consumption has never been other than negligible in tropical Africa and east, south and south east Asia. Tea consumption remained confined to East Asia until the middle of the seventeenth century. Consumption then spread to the English speaking world and the Muslim countries of the Middle East and North Africa, as well as Russia and its empire. But China remained the leading source oftea until replaced by the plantations of south and south east Asia in the 1880s. Incomes and price have been important but not always paramount factors in determining whether tea or coffee predominates. As tea has always been cheaper per litre than coffee this may explain the sway the former has always had in Asia. Japan and Korea became coffee drinkers after the growth of incomes, and American influence in the 1940s and 1950s. The presence of high incomes suggests why consumers in the countries of Western Europe and North America have been able to drink coffee in large quantities. But it does not follow that the richer countries automatically drink coffee, the poor tea. Tea was the preferred drink in Britain, Australia, New Zealand and Canada for a long period when they were among the richest countries in the world. Cultural factors have perhaps been less important than might have been expected, although the migration of the British and Irish spread tea drinking. If no simple model can be provided to explain the patterns of consumption, at least this analysis demonstrates the great diversity in drinking habits and the need to look at the geography of consumption from different viewpoints.译⽂世界上茶和咖啡:消费的模式资料来源: 2003年学术出版机构作者：葛⾥格⼤卫摘要咖啡和茶两个在多数国家被喝，但通常是⼀个占主导地位。

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concept of a personal tele-embodiment (Paulos and Canny, 1998) and an intelligent telerobot (Aude et al., 1999) were introduced recently. Most of them have the supervisory control scheme which enables users to issue high level commands. The internet time delay is variable and unpredictable so that the design of a direct control scheme which enables users to control the motion of the robot continuously may be not easy. The direct control scheme (Oboe and Fiorini, 1998) on the internet was proposed, but the modeling of the internet time delay is somewhat unreasonable. This paper proposes a novel internet control architecture for the internet-based personal robot, which guarantees that the personal robot can avoid obstacles and reduce the path error and the time difference between a virtual robot at the local site and a real robot at the remote site. An internet user can control the real robot using a simulator provided at the local site, and he/she can know a real environment of the remote site since the simulator has a virtual environment. The path error and the time difference of the internet-based personal

二语习得中的偏误分析

二语习得中的偏误分析（泛泛而论，缺乏深度）摘要：偏误分析是第二语言习得中不可缺少的研究领域。

它的研究成果对于我们认识中介语、理解语言习得的过程起重要作用，同时对语言教学实践也有深远意义。

本文介绍了偏误分析的研究发展过程及基本内容，并在此基础上探讨了偏误分析理论对于语言教学的启发。

关键词：偏误分析二语习得中介语语言迁移一．偏误分析理论背景二十世纪六十年代以前，行为主义（Behaviorist Theory）在语言学中占重要地位。

它强调语言是一种习惯。

语言的教和学重在背诵和模仿，并力求通过重复来达到语言习惯的形成。

语言学习中出现的偏误则是不容原谅的，应立即被纠正，以免对正确语言习惯的培养形成干扰。

在行为主义影响下，语言研究领域兴起了对比分析理论（Contrastive Analysis Hypothesis）。

这种理论认为语言学习是母语习惯向目标语习惯迁移的过程，当两种语言相似时，正迁移发生，当两种语言有差异时，负迁移出现。

只要对母语和目标语进行对比，了解两种语言的作用，就可预测出学习过程中的偏误，并且还可以对产生的偏误进行分析和解释。

而语言学家乔姆斯基对语言的研究使行为主义理论产生了巨大的动摇。

他认为人类对语言有与生俱来的学习能力。

人们在二语习得过程中必然会出现偏误，正如孩童在学习母语过程中也会出错，而这些错误恰恰反映了他们掌握母语的动态发展过程。

他还发现人们这两种语言学习过程有很多雷同。

科德也明确提出了偏误对语言学习的重大意义。

他指出语言学习者在学习过程中有自身的一套学习系统，而偏误正是这个系统存在的表现。

斯林柯也提出了中介语理论(Interlanguage)。

中介语指的是学习者在学习第二语言过程中产生的从其母语逐渐向目标语过渡的一个语言系统，这个系统恰恰是由于学习者在学习过程中对于目标语所做出的不准确的归纳和推论而产生的，它是一套有规则且不断变化的语言系统。

由此可见，学习者在学习过程中产生的偏误并非我们所想的无规律的不可容忍的错误，而是反映了学习者学习目标语规则的过程，对语言教学有重大意义。

组织培养英文

Plant Cell, Tissue and Organ Culture 64: 145–157, 2001. © 2001 Kluwer Academic Publishers. Printed in the Netherlands.145Oxidative stress and physiological, epigenetic and genetic variability in plant tissue culture: implications for micropropagators and genetic engineersAlan C. Cassells & Rosario F. CurryDepartment of Plant Science, National University of Ireland, Cork, Ireland (∗ requests for offprints; Fax: +353-21274420; E-mail: a.cassells@ucc.ie)Received 18 April 2000; accepted in revised form 1 December 2000Key words: DNA repair, free radicals, genetic engineering, hyperhydricity, in vitro culture, juvenility, micropropagation, mutation, reactive oxygen species, somaclonal variation, tissue cultureAbstract A number of well deﬁned problems in physiological, epigenetic and genetic quality are associated with the culture of plant cell, tissue and organs in vitro, namely, absence or loss of organogenic potential (recalcitrance), hyperhydricity (‘vitriﬁcation’) and somaclonal variation. These broad terms are used to describe complex phenomena that are known to be genotype and environment dependent. These phenomena affect the practical application of plant tissue culture in plant propagation and in plant genetic manipulation. Here it is hypothesised much of the variability expressed in microplants may be the consequence of, or related to, oxidative stress damage caused to the plant tissues during explant preparation, and in culture, due to media and environmental factors. The characteristics of these phenomena are described and causes discussed in terms of the known effects of oxidative stress on eukaryote genomes. Parameters to characterise the phenomena are described and methods to remediate the causes proposed. Abbreviations: AFLP – ampliﬁed fragment length polymorphism; FISH – ﬂuorescent in situ hybridization; HSP – heat shock proteins; PR-proteins – pathogenesis-related proteins; RFLP – restriction fragment length polymorphism; ROS – reactive oxygen species Introduction Those using tissue culture for multiplication or transformation are concerned to produce microplants that are ‘ﬁt for the purpose’, that is, free of speciﬁed diseases, vigorous, developmentally normal and genetically true-to-type (Cassells, 2000a, b; Cassells et al., 2000). The exceptions are that the market may exploit altered developmental characteristics, e.g. juvenility in herbaceous or woody plants where this results in greater productivity of the microplants when used for cutting production (George, 1993, 1996) or where tissue protocols give earlier ﬂowering (Cassells, 2000a). In general, genotype-dependent, multiplication via buds tends to be the preferred strategy to maintain genetic stability (Figure 1; George, 1993). Proliferation of side shoots from axillary buds, termed ‘nodal culture’ is preferred over proliferation of precocious axillary buds in shoot tip explants. The basis for this is that apical explants may give rise to basal explant callus from which adventitious buds may arise. The latter has been associated in strawberry with genetic variability in the progeny (Jemmali et al., 1997). It is important to mention here that epigenetic and genetic instability in the tissues used for Agrobacterium transformation (somaclonal variation: see Jain et al., 1998), that is expressed in adventitious shoots, may result in chimeral transformants (Cassells et al., 1987), and in somaclonal variation in the background of the transgenic lines (Sala et al., 2000) which may contribute to the silencing of trangenes (Matzke and Matzke, 1998). In human health the importance of oxidative stress has been long recognised in cancer and ageing studies146Figure 1. The methods of micropropagation least likely to produce plants with genetic variation (reproduced with permission; from George, 1993).(Harman, 1956). It is also recognised how complex the underlying mechanisms and processes are (Halliwell and Aruoma, 1993). The cellular mechanisms to manage stress, namely, constitutive and induced production of radical scavengers, free radical and oxidised-protein enzymatic degradation pathways and DNA repair mechanisms are highly conserved in all eukaryotes (Halliwell and Aruoma, 1993; McKersie and Leshem, 1994). Environmental and pathogeninduced stress have been investigated in detail in plants in vivo (Bolwell et al., 1995; Baker and Orlandi, 1995; Doke et al., 1996; McKersie and Leshem, 1994). Stress-like phenomena expressed in vitro and in microplants have been extensively described but less is known about the underlying causal mechanisms (Ziv, 1991; Jain et al., 1998). Both in initiating cultures and in sub-culturing, explant preparation involves wounding of the tissues which is known to cause oxidative stress (Yahraus et al., 1995). Elicitors of oxidative stress e.g. hypochlorite (Wiseman and Halliwell, 1996) and mercuric salts (Patra et al., 1997), are used to surface sterilize theprimary explants. Many factors associated with aberrations in plant tissue culture such as habituation, hyperhydricity (Gaspar, 1998) are caused by oxidative stresses (Keevers et al., 1995), such as high salt (McKersie and Leshem, 1994), water stress (NavariIzzo et al., 1996), mineral deﬁciency (Elstner, 1991), excess metal ions (Caro and Puntarulo, 1996) and possible over exposure to auxin (Droog, 1997). Oxidative stress (Gille and Sigler, 1995; Bartosz, 1997) is deﬁned as an imbalance in the pro- versus anti-oxidant ratio in cells and results in elevated levels of pro-oxidants (ROS: reactive oxygen species; including superoxide, hydrogen peroxide hydroxyl, peroxyl and alkoxyl radicals) (Wiseman and Halliwell, 1996) which can cause cell damage (Sies, 1991). ROS (Figure 2) can react with a spectrum of metabolites, proteins including enzymes, and nucleic acid molecules (Gille and Siegler, 1995). Oxidised enzymes which may be inactivated, are degraded by cytosolic proteinases (Laval, 1996). The inﬂuence of ROS, through altered cell redox potential, on the cell cycle and oxidative damage to both nuclear and organellar147Figure 2. Reactive oxygen species (ROS) produced constitutively in the cell. The upper section shows the natural antioxidants and enzymes used to minimize the toxic effects of ROS. The lower section gives selected examples of the harmful effects of ROS when the pro- and anti-oxidant balance is perturbed in oxidative stress. (MDE, malondialdehyde; HNE, 4-hydroxynonenal).DNA, may result in mutations (Figure 3; Bohr and Dianov, 1999). Oxidative damage in eukaryote cells is expressed in altered hyper- and hypomethylation of DNA (Kaeppler and Phillips, 1993; Tilghman, 1993; Wiseman and Halliwell, 1996; Cerda and Weitzman, 1997; Wacksman, 1997); changes in chromosome number from polyploidy to aneuploidy, chromosome strand breakage, chromosome rearrangements, and DNA base deletions and substitutions (Gille et al., 1994; Czene and Harms-Ringdahl, 1995; Hagege,1995). Such changes could explain, at least in part, the range of variability found in plant cells, tissues and organs in culture and in microplants, namely, recalcitrance including loss of cell competence (Hagege, 1995; Lambe et al., 1997), hyperhydricity (Olmos et al., 1997) and somaclonal variation including epigenetic and genetic variation (Jain et al., 1998; Joyce et al., 1999; Kowalski and Cassells, 1999). The objective of this review is to discuss tissue culture variability, its causes, detection and remediation148 with emphasis on the possible role of oxidative stress in this phenomenon.Aberrations and variation expressed in vitro At the outset it should be recognised that explants, other than buds, from dicot plants have different characteristics to those from monocots, speciﬁcally those of dicots may have a cambium; that there are differences in organogenetic potential between families, genera, species and genotypes; and that different genotypes of a species may show widely different responses (George, 1993, 1996). Further there are differences in the responses of explants from different parts of a plant, which change ontogenetically (George, loc. cit.). Some trends are evident, e.g. increased recalcitrance with advancing age of the cultures (Hagege, 1995) and increased somaclonal variability in microplants with increasing sub-culture number (Brar and Jain, 1998). With a given genotype, wounding of the tissues on cutting (excision), and tissue damage and exposure to sterilants during sterilisation, and suboptimal in vitro factors (Ziv, 1991) are important in relation to genomic damage. So called ‘pre-existing’ genomic diversity at the cell level (D’Amato, 1964; Figure 4) and wound or oxidative damage due to wounding may explain some of the variability subsequently seen in vitro and in the resulting microplants. Possible stress due to unbalanced media, bad culture vessel design and environmental stress may also, or further, contribute to the genetic, epigenetic (developmental) and physiological variability recorded (Ziv, 1991). Wounding or excision per se may be considered both as a trigger for cell division (Sangwan et al., 1992) and as a damaging oxidative burst (Schaaf et al., 1995; Yahraus et al., 1995). As a consequence of the above factors, explants may senesce, fail to respond, undergo cell division and/or produce adventitious organs or somatic embryos. In responding genotypes, the response is generally regulated in a predictable way by manipulation of the auxin to cytokinin ratio and absolute growth regulator concentrations (Skoog and Miller, 1957). In some cases, recalcitrance may be overcome by pulsing in sequence with auxin followed by cytokinin (Christianson and Warnick, 1985). Whether genome variability is ‘pre-existing’, caused by oxidative stress on wounding an/or caused by stress in culture (Figure 4), selection may begin in vitro with the appearance of sectoring in the callus (D’Amato et al., 1980). Cell lineFigure 3. Changes in DNA caused by oxidative stress which can lead to recalcitrance, loss of competence, hyperhydricity and somaclonal variation.selection for in vitro conditions may result in loss of competence; e.g. selection based on ﬁtness of grossly altered genotype(s) may result in the irreversible loss of competence (Hagege, 1995). The main morphological aberration seen in shoots in vitro cultures, both in nodal/bud derived shoots and in adventitious shoots, is hyperhydricity (‘vitriﬁcation’) (Debergh et al., 1992). This term is used to describe aberrant morphology, typically hyperhydrated, translucent tissues and physiological dysfunction in plant tissues in vitro (Ziv, 1991). It is also associated with leaf-tip and bud necrosis. The latter often leads to loss of apical dominance in the shoots and is associated with callusing of the stem base. An important characteristic of this condition is impaired stomatal function which causes problems in establishing microplants (Preece and Sutter, 1991). Morphological variability in plants from in vitro culture may be seen in intrapopulation variability (within a population of adventitiously regenerated plants) (Kowalski and Cassells, 1998) and interpopulation variability (between populations of in vitro plants) (Joyce et al., 1999). The latter may arise when plants are propagated on different media or in culture vessels with different characteristics (Joyce et al., 1999). Intrapopulation variability can be a result of the loss of speciﬁc viruses, including cryptic viruses, from some of the regenerated plants (Matthews, 1991); chimeral breakdown, rearrangement and/or synthesis of unstable chimeral plants (Tilney-Bassett, 1986). In generally, heritable somaclonal variation (Larkin and149Figure 4. Sources of genetic variation in plants obtained through organogenesis in callus cultures (reproduced with permission; from George, 1993).Scowcroft, 1981) has the characteristics of mutation (Anonymous, 1995; Jain et al., 1998), albeit occurring at higher frequency than occurs spontaneously in seed or vegetative propagules (Preil, 1986). It is genotype-dependent and dependent on the pathway of regeneration (Karp, 1991). Epigenetic changes can occur in vitro culture resulting in ‘apparent rejuvenation’ (Pierik, 1990) affecting woody and herbaceous plants (Huxley and Cartwright, 1994; James and Mantell, 1994; Jemmali et al., 1994; Cassells et al., 1999 a, b). Interpopulation variation is usually cryptic, as control populations are not available for comparison; it is recognised in quality differences in plants produced by different protocols or by different micropropagators (GrunewaldtStoker, 1997). Examples of interpopulation variability are populations differing in degree of hyperhydricity or juvenility (Swartz, 1991). While woody plant propagators are familiar with phase change (Howell, 1998), micropropagators of herbaceous plants appear less conscious of this phenomenon but it has implications for disease susceptibility in that polygenic resistance develops as the plant soma matures (Agrios, 1997) and for time to ﬂowering (Howell, 1998). Plants showing prolonged juvenility (epigen-etic/ontogenetic variability) may be more susceptible to damping-off diseases (Agrios, 1997). This is not always the case, as juvenile tissues are reported to have enhanced resistance to fusaric acid (Barna et al., 1995) and Cassells et al. (1991) have shown that potato crops derived from microplants, showing juvenility compared to a tuber-derived crop, were more resistant to potato blight. In vitro plants may have a longer time to ﬂowering compared to those from vegetative propagules (Cassells et al., 1999a). While morphological intrapopulation variability and ontogenetic and physiological variation, expressed in interpopulation variability, are well recognised phenomena in micropropagation, cryptic intrapopulation variation in juvenility has also been detected in adventitiously regenerated plant populations showing genetic variation (Kowalski and Cassells, 1998) suggesting that genetic and epigenetic variability are not necessarily discrete but can occur in the same population. Somaclonal variation is strongly expressed after the microplant population establishment stage as interplant variation in morphological characters. Some of the plants may show characteristics of chimeral breakdown (Tilney-Bassett, 1986). Somaclonal variation has been extensively reviewed in Jain et al. (1998).150Figure 5. Showing the consequences of oxidative stress from induction of host antioxidant defences (repair, heat shock protein induction, pathogenesis related protein induction) to mutation, programmed cell death and uncontrolled cell death. Figure 6. The relationship between stress inducers e.g. medium salt stress, gene activation and the generation of biomarkers for stress remediation and stress damage repair. Examples of damage exposure are ethylene and ethane; of damage are oxidised bases e.g. 8-oxoguanine; of remediation are glutathione and glutathione reductase and of repair, Poly(ADP-ribose) polymerase (see text for further markers).As discussed above, shifts in characters in populations, e.g. physiological or developmental changes, are not readily recognised unless control populations are available (Cassells et al., 1997). These can, however, be visually expressed in loss of apical dominance, leaf number and leaf size and, more importantly in the time to ﬂowering, and yield quality e.g. tuber number and size distribution in potato seed production (Cassells et al., 1999a).Characterisation of epigenetic and genetic changes in microplants pre- and post- establishment Cytometric analysis of callus has shown variability in chromosome number and ploidy in tissue culturederived plants (Geier, 1991; Gupta, 1998). Investigations indicate more chromosome variability in the callus phase than in adventitious shoots (D’Amato et al., 1980), indicating a loss of competence in the more seriously disturbed genomes (Valente et al., 1998). Cell line selection for secondary product formation also shows differences at the metabolite level (Berglund and Ohlsson, 1995). While occasional albino shoots are observed, the expression of morphological variation is difﬁcult to assess in vitro due to variability between shoots due to temporal differences in shoot initiation and because of the limited leaf expansion in in vitro cultures. Variability in both qualitative and quantitative traits has also been reported (Karp, 1991). The latter expressed in increased standard deviations of the character mean (DeKlerk, 1990) and can be quantiﬁed using computerised image analysis (Cassells et al., 1999a). Analysis of DNA-base methylation and various genetic ﬁngerprinting techniques have also been used to conﬁrm and characterise variability in tissue culturederived plants, conﬁrming both morphological and cryptic genetic and epigenetic variability between and within populations (Karp et al., 1998; Cassells et al., 1999b).Current views on the molecular basis of somaclonal variation In recent years plant cell, tissue and organ culture has been developed for applications in plant genetic manipulation (Cassells and Jones, 1995). In this ﬁeld, somaclonal variation has attracted considerable interest as a means of improving crop plants (Jain et al., 1998). Reviews discussed a number of mechanisms to explain somaclonal variation, these included changes in chromosome number, chromosome breakage and rearrangement, DNA ampliﬁcation, point mutations, changes in DNA methylation, changes in organellar DNA, activation of transposons (Frahm et al., 1998; Gupta, 1998; Henry, 1998; Jain et al.,151 1998; Kaeppler et al., 1998). The mechanisms appear to be equally applicable to explaining the basis of variation at the cell and callus level and are similar to the variability resulting from oxidative genome damage and induced mutation. Nagl (1990) has discussed the relationship between stress-induced and ontogenetic changes in plant genomes arguing that plant genomes are inherently ﬂuid. In some genomes, e.g. ﬂax (Schneeberger and Cullis, 1991) and banana (Cullis and Kunert, 2000) there are well characterised genomic instabilities associated with somaclonal variation. (Figure 5). In addition to the above ROS, chemical and physical agents can stimulate lipid peroxidation that can become autocalatytic resulting in the production of organic hydroperoxides (Figure 2). ROS in the presence of iron and copper ions may generate highly mutagenic compounds, e.g. peroxyl radicals and alkoxyl radicals (Koh et al., 1997). The primary response to elevated ROS production (Figure 2) is stimulation of production of antioxidant molecules (radical scavengers) such as ascorbic acid and glutathione in the aqueous phase and alpatocopherol and carotenoids in the lipid phase (Gille and Sigler, 1995) and the activation of antioxidant enzyme systems including superoxide dismutase, catalase and glutathione and ascorbic acid peroxidases (Tsang et al., 1991; Larson, 1995; Smirnoff, 1996). Additional responses involve the activation of heat shock proteins to protect enzymes systems against ROS damage (Burdon, 1993) and of proteases to degrade damaged proteins (Stadtman, 1992). More signiﬁcant is the potential of ROS to cause DNA damage (‘genotoxicity’; Wiseman and Halliwell, 1996). The cell cycle slows or shuts down to minimise the transmission of mutations to daughter cells through mitosis and to facilitate DNA repair (Logemann et al., 1995; Amor et al., 1998; Reichheld et al., 1999) and DNA repair mechanisms, the SOS response, are activated (Laval, 1996; Yamamoto et al., 1997; Vonarx et al., 1998). The outcomes of oxidative stress depend on the balance between pro and anti-oxidants responses. Imbalance may lead to controlled responses (Figure 5) such as induced resistance to pathogens (Ernst et al., 1992), excessive imbalance to cell damage and mutation (Wiseman and Halliwell, 1996), possible programmed cell death (apoptosis) (Polyak et al., 1997) and, in the extreme, to (unprogrammed) cell death (Hippeli and Elstner, 1996). Oxidative stress has been linked to recalcitrance in protoplast culture (Benson and Roubelakis-Angelakis, 1994). Increase in ROS is associated with a range of biotic and abiotic stresses (Gile and Siegler, 1995; Bartosz, 1997). These include salt, drought, heat, and UV-induced stresses. They are also induced by chemical and physical mutagens (Anon, 1977). Their protective and constitutive roles include direct protection against pathogen attack, and involves the role of H2 O2 as a messenger in the induction of host resistance (pathogenesis-related (PR) protein induction) (Lamb and Dixon, 1997). H2 O2 may have a role in xylem formation and other cell-death processes in plants (Howell, 1998). ROS have a role in creatingThe relationship between somaclonal variation and spontaneous mutation The paper of Shepard et al. (1980) on somaclonal variation in potato stimulated interest in the application of this variability in crop improvement but was soon followed by concern about the quality of somaclonal variation and whether it differed qualitatively from spontaneous mutation (Sanford et al., 1984). This issue has been discussed by Karp (1991, 1995) but while it is still controversial, somaclonal variation is used in plant improvement, with induced mutagenesis whose efﬁciency has been improved by exploiting in vitro plant systems (Cassells, 1998). More importantly here, induced mutation and somaclonal variation result in a qualitatively similar, if not quantitatively identical, spectrum of DNA changes (see Figure 3). The issue is whether somaclonal variation and other tissue culture variability are mechanistically like physically-induced mutation and are caused by reactive oxygen species (Anonymous, 1977; 1995; Micke and Donini, 1993).Oxidative stress and mutation Oxidative stress is caused by the unremediated hyperactivity of reactive oxygen species (Figure 2). ROS such as superoxide, hydrogen peroxide and the hydroxyl radical are metabolic intermediates in respiration and photosynthesis and other metabolic activities in plants (see review by Gille and Sigler, 1995; Bartosz, 1997). Their natural cytoplasmic toxicity and genotoxicity is controlled by antioxidants and enzymic pathways in the cell (Hippeli and Elstner, 1996). Various environmental signals (Bartosz, 1997), which lead to an increase in ROS are associated with induced mechanisms to minimise their harmful effects152 variability in the plant genome by activating transposons (Mhiri et al., 1997), inducing polyploidy, chromosome breakage/rearrangements and base mutations (Figure 2). DNA based changes induced by ROS may inhibit methylating enzymes leading to hypomethylation (Cerda and Weitzman, 1997; Wacksman, 1997), e.g. formation of 8-oxoguanine occurs at high frequency which may lead to mismatch at DNA repair (base mutation, e.g. AT–GC changes), similarly for other oxidative base changes. While much of the ROS-induced effects due to wounding may be localised, some ROS can migrate across membranes, e.g. H2 O2 and cause effects directly, or via membrane lipid peroxidation, at the level of DNA in the stressed cells or in neighbouring cells (Figure 2). A gradient of stress damage from the wound area back into the explant may be hypothesised. ROS (and physical mutagens) have been conﬁrmed in animal cells (Halliwell, 1999) as causing the range of epigenetic and genetic changes in DNA that are problematic in plant tissue culture (Figure 3). number and DNA content (Quicke, 1993; Curry and Cassells, 1998). Techniques including ﬂuorescent in situ hybridisation (FISH) (Maluszynska and HeslopHarrison, 1991) and Giemsa banding (Quicke, 1993) are used to look for somatic recombination, including chromosome breakage and rearrangement and may also be used to detect DNA ampliﬁcation and reduction. Changes in DNA base methylation can be investigated using methylation-sensitive restrictions in RFLP and AFLP analysis (Karp et al., 1998) or by PCR of bisulphite modiﬁed DNA (Joyce et al., 1999).Plant hormones and oxidative stress Plant hormones implicated in hyperhydricity (vitriﬁcation) include cytokinins, auxins, and the auxin/cytokinin ratio; gibberellic acid and ethylene (Ziv, 1991; George, 1996). Oxidative stress has been associated with auxin and cytokinin metabolism in Agrobacterium induced tumours (Jia et al., 1996). Ethylene is also strongly linked to oxidative stress (McKersie and Leshem, 1994; Pell et al., 1997). Injury has been shown to activate the oxidation of IAA, while kinetin is reported to be a secondary product of oxidative stress (Barciszewski et al., 1997). In vitro, various media factors have been shown to induce stress, including hormones, and mineral nutrients (Ziv, 1991; George, 1993, 1996) there is evidence that metal toxicities and deﬁciencies may generate ethylene through oxidative stress (Lynch and Brown, 1997). Oxidative stress also affects cytosolic calcium (Price et al., 1994). Oxidative stress has been suggested as a cause of guard cell malfunction (McAnish et al., 1996). Calcium has been implicated in increased stress tolerance (Gong et al., 1997).Parameters used to characterise oxidative stress A number of methods have been used to monitor/characterise oxidative stress (Figure 6). These include measurement of the redox potential (Reichheld et al., 1999), measurement of stress related metabolites e.g. ascorbic acid (Smirnoff, 1996), glutathione (de Vos et al., 1994), hydrogen peroxide (Schreck et al., 1996). Ethylene has been monitored in hyperhydricity (‘vitriﬁcation’) studies (Keevers and Gaspar, 1985) and along with ethane, a marker for lipid peroxidation, has been used to monitor stress in vitro (Cassells et al., 1980; Cassells and Tamma, 1985). Thiobarbituric acid reactive substances are also used to assess lipid peroxidation (Laszczyca et al., 1995). 8oxo-2 -deoxyguanosine (Kasai, 1997; Bialkowski and Olinski, 1999) is considered to be a reliable indicator of genotoxicity as are other bases modiﬁed by ROS (Yamamoto et al., 1997). Enzymes of oxidative metabolism (Mehlhorn, 1990), enzymes associated with the cell cycle (Chiatante et al., 1997), enzymes of the SOS response (Laval, 1996; Wiseman and Halliwell, 1996) e.g. poly(ADP-ribose)-polymerase (Amor et al., 1998), screening for heat-shock proteins (HSP) (Burden, 1993) and PR proteins (Glandorf et al., 1997) have also been used as oxidative stress monitors. Karyotyping, ﬂow cytometry and microdensitometry can be used to measure changes in chromosomeRemediation of oxidative and other tissue culture associated stresses Remediation of oxidative stress can be based on several strategies. Genotypes can be screened for their sensitivity to stress and sensitive genotypes avoided; or they can be bred, mutated or engineered for increased stress tolerance (Gupta et al., 1993). The breeding/genetic manipulation options are both relatively long-term and costly and can only be applied to individual genotypes (Jones and Cassells, 1995). An important consideration where plant tissue culture is used for cloning or transformation is the choice153 of the explant. While mature plant tissue may be polysomatic (D’Amato, 1964), this may not be so in the case of the tissues of young plants in vitro (Curry and Cassells, 1998; Curry and Cassells, unpublished). Selection of explants from the latter may avoid the problem of ‘pre-existing’ variation (Figure 4). The main option, however, is the use of stable pathways of multiplication (Figure 1: George, 1993, 1996); albeit, even with these genetic drift may occur (Jemmali et al., 1997). There is evidence e.g. that protoplasts give rise to greater variability than tissue explants as expressed in the greater variability in plants regenerated from the former (Sree Ramulu et al., 1984). This may reﬂect expression of somatic cell variability (Figure 4) but it also appears to reﬂect the stress experienced in their isolation and regeneration where they are exposed to osmotic stress and the toxic effects of cell wall degrading enzyme preparations (Cassells and Tamma, 1985) and this has implication for their use in transformation via electroporation or biolistics at the protoplast level (Christou, 1995) as opposed to bombardment of apices (Sautter et al., 1995). The immediacy of the oxidative stress caused by excision and manipulation (Yahraus et al., 1995) would suggest that treatment of the explant after excision would be relatively ineffectual. As an alternative, it is suggested that stress be applied to the donor plant (or in vitro microplant) before excision. Under in vivo conditions, it was been shown that stress exposure induces cross-stress tolerance, e.g. UV treatment not only increases tolerance to further UV exposure but also to pathogen induced stress (Ernst et al., 1992), similarly paclobutrazol which is used in vitro and in weaning treatments (George, 1993, 1996) reduces oxidative stress to high light and high temperature (Mahoney et al., 1998). It has been suggested that induction of heat shock proteins be used to protect against oxidative stress (Banzet et al., 1998; Sebehat et al., 1998). Prevention or reduction of oxidative stress damage in vitro may be possible by manipulating hormone and mineral nutrients using the above oxidative stress parameters to monitor the protocols as has been done in the case of protoplasts (Cassells et al., 1980; Cassells and Tamma, 1985). In vitro calli and tissues are more amenable than intact tissues to permeation techniques. Cells, calli and explants can be inﬁltrated and bathed with radical scavengers such as ascorbic acid, mannitol and dimethyl sulphoxide. The stress messenger hydrogen peroxide can be broken down by extracellular catalase. Manipulation of media composition, particularly using simple media formulations in autotrophic or microhydroponic culture (Cassells, 2000a) and modiﬁcation of culture vessel design to facilitate controlled gaseous exchange (Cassells and Walsh, 1998), can greatly inﬂuence microplant resistance to hyperhydricity and improve ontogenic development (Cassells, 2000b).Conclusions It is speculated here that problems underlying the application of plant tissue culture systems in plant cloning (micropropagation) and genetic transformation, namely, recalcitrance, hyperhydricity, poor physiological quality, genetic and epigenetic variation, may have a common basis, at least in part, in oxidative stress-induced damage. This damage is caused by an overwhelming of the antioxidative defenses by primary ROS and secondarily, by the production of ROS by lipid autocatalytic peroxidation (Figure 2). While damaged proteins may be broken down by proteinases, damage is ﬁxed in the DNA. Speciﬁc levels of DNA damage may result in cell death or programmed cell death, other levels in loss of cell competence, altered methylation patterns may result in epigenetic changes, or in mutations (Figure 3). Somaclonal variation shows a similar spectrum of genetic variation to induced mutation; and oxidative stress and irradiation are known to involve ROS. Oxidative stress damage which it is emphasised is genotype dependent, may also operate at the physiological level since ROS have been shown to inﬂuence plant hormones namely, cytokinin, auxin, ethylene metabolism. Oxidative stress also inﬂuences calcium metabolism which in turn is involved in auxin transport, guard cell function and as a secondary messenger. Remediation strategies have been proposed and some makers of oxidative stress listed. It is suggested that induction of heat shock proteins may confer cross tolerance to the stress phenomena encountered as problems in establishing plant tissue cultures. Media and environmental manipulations should be carried out aimed at reducing in vitro stress based on adjusting the media composition and the physical culture environment, paying special attention to hormone stress, mineral composition and water and light stress. Reactive nitrogen species (NOS) not discussed here, can。

外文期刊简介

外文期刊简介社会科学刊号: 336B0046 ISSN:0889-4019 期数:4 状态:正常出版中图类:C91刊名:The Career Development Quarterly.刊价:USD 151.00(参考价格) 创刊年:1952出版者:ACPA 出版地:美国译名简介:《职业发展季刊》探讨职业发展的理论与实践，涉及就业咨询信息、劳动力市场动态与职业教育等方面内容。

(文种：英文)政治、法律刊号: 300B0005 ISSN:期数:52 状态:正常出版中图类:D刊名:Time. (Asia Ed.)刊价:USD 143.00(参考价格) 创刊年:1946出版者:Time Magazine, (Asia Ed.) 出版地:美国译名简介:《时代》（亚洲版）基本内容与其美国版(300B0004)相同，但增加亚洲情况的报道。

在东京出版。

经济教育刊号: 380B0240 ISSN:1066-8926 期数:12 状态:正常出版中图类:G4刊名:Community College Journal of Research and Practice.刊价:USD 728.00(2007年) 创刊年:1976出版者:Taylor & Francis 出版地:美国译名简介:《社区学院研究与实践杂志》论述美国社区学院和初级学院教育，旨在交流信息、观点、研究成果和教学经验。

(文种：英文)刊号: 380C0005 ISSN:1363-9080 期数:5 状态:正常出版中图类:G4刊名:Journal of Education and Work.刊价:USD 767.00(2007年) 创刊年:1988出版者:Taylor & Francis Ltd., Carfax Publishing 出版地:英国译名简介:《教育与工作杂志》主要关注从学校到工作就业转变过程中的各类问题。

(文种：英文)刊号: 380C0052 ISSN:0007-1005 期数:4 状态:正常出版中图类:G4刊名:British Journal of Educational Studies.刊价:GBP 337.00(2007年) 创刊年:1952出版者:Blackwell Publishers Ltd. 出版地:英国译名简介:《英国教育研究杂志》刊载教育问题，包括教育基本原则、教育理论与实践，以及相关哲学、历史、心理与社会等方面的论述。

基于Dymola的航空发动机尾喷管建模与仿真

定关系。文献［3］、［ 4 ］推导出 A7 / A n 及 A n / A2 随 M0 的变化关系，其中 A7 为喷管出口面积， A n 为喷管喉部面积， A2 为压气关系式如下机进口面积， M0 为飞行马赫数。 A7 p t6 = ・ An p t7 An = A2 T t7 A （ M7 ）・ * T t6 A
仿真设置对话框
果。图中有两个公共接口（ Port）： Port A 和 a， Port A 将与 A中最后一级涡轮的出口连接， a 将与环境模块连接。Port
声明了三个变量：总温、总压和流量。 a 是热流体库（ ThermoFluid）提供的接口，声明了与环境模块有关的一些变量。各种接口可以由库中直接拖放至图形编辑窗口中使用。在该模块的 Modelica 程序文本窗口中定义该模块类，首先继承（ extends）基模块，然后声明其他变量及参变量，并列出相关的方程。这样就完成了对收 - 扩喷管的建模工作，该模块将被用来组装航空发动机整机模型，以便对其性能进行仿真。新建一个模块，用模型库中已有的模块来搭建发动机模型。图 4 为一种组装好的带有收敛喷管的双轴涡扇发动机模型结构图。其中的收敛喷管模块即为前述过程中建立好的喷管模块，由模块浏览器中直接拖放至该主窗口即可使用。
Modeiica 程序文本窗口中定义该基模块类，声明基本的变量及参变量，并列出基本的方程。另新建一个模块（ modei），绘制图标。图 3 为 Dymoia4. 3c 环境下建立的收 - 扩喷管模块图
— 61 —
示。
图5 图3 Dymola4. 3c 环境下建立的收 - 扩喷管模块图示
1
引言
航空发动机具有严重非线性，且工况和工作范围变化

参考文献格式

文献引用格式1. 直接或间接引述某人的具体观点，须给出文献的页码；转述某人基本观点或仅提及其某文献，只需给出文献的出版年份。

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3．如某个作者在同一年发表/出版了多篇/本著述，在出版年份后加“a、b、c”等来区分。

4. 参引用夹注标示，其格式为：（作者名＋空格＋出版年份＋冒号＋页码）（注意：作者名之后不用标点）。

引用格式示例：（1）一般情况示例：（王刚1995：20）；王刚（1995：20）；（王刚1995：20、25）；（王刚1995：20－25）。

（2）同一中文著述如有两个作者，作者名之间用顿号连接：（王刚、张力1995：20）；如超过两人，第三人起不再列出，用“等”表示，如：（王刚、张力等1995：20）。

（3）同时参引一个作者两种以上的著述：（王刚1992，1995）；（王刚1995a，1995b）。

（4）同时参引不同作者的著述，中间用分号隔开：（王刚1995；张力、李涛2001：20）。

（5）同时标示著述首次发表/出版时间和所引用版本的出版时间，中间用斜杠隔开，引文的具体页码见所引用的版本，如：吕叔湘（1977/1983：137）。

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”（苏力2007：43）“……，最终导致交际的失败”（王刚1995：20）。

认知语言学认为（Lakoff & Johnson 1980: 115），“……”。

参考文献排列格式（一）共性要求1．“参考文献”四字统一用5号粗黑宋体标示，首字与正文左边对齐。

2．文中没有参引的著作或文章一律不列入参考文献。

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Continuous cellulose fiber-reinforced cellulose ester composites.

Cellulose8:161–169,2001.©2001Kluwer Academic Publishers.Printed in the Netherlands.161Continuous celluloseﬁber-reinforced cellulose ester composites.II.Fiber surface modiﬁcation and consolidation conditionsKevin C.Seavey&Wolfgang G.Glasser∗Biobased Materials Center,Department of Wood Science and Forest Products,Virginia Tech,Blacksburg, Virginia24061∗Author for correspondence(E-mail:wglasser@)Received15August2000;accepted11April2001Key words:cellulosic composites,ﬁber acetylation,consolidation,cellulose acetate butyrateAbstractWe prepared thermoplastic composite panels using solution impregnation of continuous lyocell(regenerated cel-lulose)ﬁbers with a cellulose mixed-ester(cellulose acetate butyrate)matrix.We examined bothﬁber-matrix adhesion and melt consolidation in an effort to produce uniform panels having low void content and high mech-anical strength.We characterized the effect of surface modiﬁcation by acetylation on interfacial adhesion between the celluloseﬁber and cellulose ester.Whereas woodﬁber acetylation had previously been observed to result in signiﬁcant strength gains in(discontinuous)woodﬁber-reinforced composites(with the same matrix material), we did not observe a similar increase in strength in the continuous lyocell celluloseﬁber system.This suggests that interfacial stress transfer is not a limitation in this system.This was conﬁrmed by microscopic examination of the fracture surfaces,which indicated thatﬁber-matrix adhesion was considerable in the absence ofﬁber surface modiﬁcation.We then systematically varied melt consolidation conditions(temperature,pressure and time)in an attempt to deﬁne optimum consolidation parameters by using design of experiments(DOE)methodology.We measured both interlaminar shear strength(ILSS)and composite void volume.We found that a minimal void content(ca.2.83vol.%)occurred at moderate temperatures(200◦C),low consolidation pressures(81.4kPa)and long press times(13min).This was also where we maximized the interlaminar shear strength(ILSS)at a value of16.3MPa.This agrees with the regression model predictions.We observed the highest tensile properties at the ILSS and void-volume optimal-consolidation condition:a tensile modulus of22GPa and tensile strength of 246MPa were obtained.IntroductionLyocellﬁbers represent a new type of regenerated celluloseﬁber that is produced on an industrial scale from solutions of N-methyl morpholine-N ox-ide(NMMO)/water.Lyocellﬁbers have been found to have high strength and are potentially useful forﬁber-reinforced composites.Previous research on lyocell ﬁber-reinforced composites has been motivated by the environmental aspects of a biodegradable material;by the CO2-neutrality of a composite based entirely on renewable resources;and by the more pleasant feel of a material in contact with human skin,as suggested by their use in tool handles and automobile steering wheels(Rouse,1965).In the previous article in this series(Seavey et al., 2001),the authors examined different manufactur-ing alternatives.In particular,this includedﬁber op-tions such as fabric and continuous tow,and mat-rix deposition options such as powder prepregging,ﬁlm stacking,and solution impregnation.The res-ults demonstrated that solution-impregnated continu-ous tow produced the best results;that surface wetting and matrix-to-ﬁber adhesion was adequate to avoid widespreadﬁber pullout(interfacial delamination); and that the tensile modulus followed rule-of-mixing162behavior.Although the ultimate tensile strength of uni-directional composites increased withﬁber content as well,this increase was less than expected based on the rule-of-mixing model.We expect this behavior given that we are dealing with a brittle-matrix composite system.In an effort to improve the mechanical properties of the lyocellﬁber/cellulose acetate butyrate(CAB)-composite system,we have undertaken the following objectives:(1)To improve the interfacial characteristics usingﬁber surface acetylation;and(2)To vary the manufacturing parameters in order todetermine what conditions(i.e.,temperature,pres-sure,and press time)are optimal for fabricating a composite having minimal void content as well as maximum interlaminar shear strength.Acetylatedﬁbers have been used in the previ-ous manufacture of biobased polymer composites. Glasser et al.(1999)prepared thermoplastic com-posite materials with CAB as matrix using discon-tinuous water extracted steam explodedﬁbers,alkali-extractedﬁbers,untreated oatﬁbers and acetylated ﬁbers.They found that the acetylated lignocellulosic ﬁbers had considerable adhesion to a thermoplastic cellulose ester over that of chemically-unmodiﬁed ﬁber,as evidenced by a decrease in theﬁber pull-out phenomena.Devi et al.(1997)produced acetylated pineapple leafﬁber reinforced polyester composites. Bothﬂexural as well as tensile properties increased signiﬁcantly over neat matrix with the inclusion of modiﬁedﬁber.In order to complete our objectives,we monitored interfacial characteristics through tensile testing of unmodiﬁed/modiﬁedﬁber composites followed by mi-croscopic evaluation of the resulting fracture surfaces. We then systematically varied press conditions using a design of experiments scheme while monitoring inter-laminar shear strength,void andﬁber volume content withinﬁnal composites,as well as tensile behavior of the manufactured materials.ExperimentalMaterialsMatrixCellulose acetate butyrate(CAB381-20)was the same material used in the previous study(Seavey et al.,2001).It was obtained in powder form from Eastman Chemical Company,Kingsport,Tennessee.Its average acetyl and butyryl contents were13.5and38.1wt.% and the falling ball viscosity was20s(76poise).The number average molecular weight(M n)was69,600 with a molecular weight distribution of1.83.FibersThe continuous celluloseﬁbers used in this study were also the same described in the previous report(Seavey et al.,in press).Acordis of Coventry,England,sup-plied the lyocellﬁbers.The tows consisted of16,700ﬁlaments,each ca.11µm in diameter and1.4dTex in ﬁneness.We prepared acetylated lyocellﬁbers using the following procedure.We suspended lyocell tow (16m length)above200ml of acetic anhydride in a 3.785dm3Parr(Moline,IL)pressure reactor.We then evacuated the reactor using an aspirator and raised the temperature to150◦C where it was held constant for 24h.Afterwards,we quenched theﬁbers in a water bath for8h,then dried them overnight in a laboratory hood and subsequently overnight in a vacuum oven at room temperature.We quantitatively assessedﬁber acetylation using FTIR spectroscopy(i.e.,absorption peak centered around1748cm);and we also observed evidence suggesting the presence of acetyl groups using the aminolysis procedure described previously (Seavey et al.,2001).MethodsPreparation of unidirectional composite prepregs We preimpregnated(prepregged)theﬁber tows with a12%(w/w)solution of CAB in accordance with the procedure described previously(Seavey et al.,2001) with minor modiﬁcations.For theﬁber acetylation study,we used acetone as solvent instead of MEK be-cause of higher volatility and greater ease of handling. We used both acetylated and unacetylatedﬁbers.For the melt consolidation study,we prepregged continu-ous(unmodiﬁed)ﬁber tow using theﬁber sizing appar-atus of Broyles et al.(1998)as described previously (Seavey et al.,2001).Melt consolidationFor the acetylation study,we consolidated prepregs under heat and pressure in a Carver laboratory heated press in accordance with earlier work(Seavey et al., 2001)with minor adjustments.163In the melt consolidation study,we stacked prepregged panels unidirectionally three at a time.We then consolidated them under varying time,temper-ature and pressure conditions in the vacuum press described previously(Seavey et al.,2001).We then raised the press plates to temperatures of170,200 or230◦C.We preheated the prepregs without pres-sure for2min.We then instantaneously raised the pressure to81.4,163,or245kPa for times of3,8 or13min.We held the temperature constant under vacuum.Fiber content analysisWe conductedﬁber-volume-fraction determination us-ing the aminolysis/gas chromatography procedure of Mansson and Samuelsson(1981)as described pre-viously(Seavey et al.,2001).We used this proced-ure to detect the amount of original butyryl groups present in the original composite sample.We then back-calculated the matrix volume fraction within the composite,which led to theﬁber volume fraction. Density analysisWe determined the densities of the composites using ASTM D792-91,test method A with isopropyl alcohol as the test liquid as described previously(Seavey et al., 2001).Fiber and matrix density was taken to be1.5 and1.2g/cm3,respectively.Tensile testingWe cut rectangular specimens from composite pan-els using aﬁne bandsaw.These specimens measured 10cm(4inch)long,1.25cm(0.5inches)wide and ca.1.2mm thick for the acetylation study and4mm thick for the consolidation study.We performed tensile tests using an Instron testing machines model4204with a load beam of15kN in a laboratory environment.We kept the crosshead speed at2mm/min for all tests. We measured the strain using an MTS strain gauge. We conducted the tests at room temperature.Reported data points represent the average of5measurements. We conditioned test specimens at room conditions for greater than40h.We measured modulusﬁgures by taking the slope between0.1and0.3%strain(ca.25% of failure strain).Interlaminar shear testing1along theﬁber direction (ASTM D2344–84)We cut rectangular specimens from composite pan-els using aﬁne bandsaw.These specimens measured 1Only performed for consolidation optimization study.5cm(2inches)long,0.625cm(0.25inches)wide and ca.4mm thick.We performed short beam shear tests using an Instron testing machines model4204with a load beam of5kN in a laboratory environment.We kept the crosshead speed at1.3mm/min for all tests. We kept the span constant at19.05mm.We conducted the tests at room temperature.Reported data points represent the average of10measurements.We con-ditioned the test specimens at room conditions for greater than40h.We calculated the apparent shear strength(s H)using the following equation(ASTM D 2344–84):s H=0.75P Bbd(1) where b represents width of specimen;d is thickness of specimen;and P B is breaking load. Experimental design1A suitable approach to observe the effects of in-put variables such as time,pressure and temper-ature on output variables such as composite qual-ity is design of experiments(DOE)(Schmidt& Launsby,1993).A designed experiment is typically much more efﬁcient at collecting necessary data to understand a process than an experiment in which one variable is manipulated at a time.The Box–Behnken fractional factorial designed experiment is particularly useful in modeling processes with3-level (i.e.,pressure1,pressure2,pressure3)quantitat-ive variables and we chose this design to under-stand the consolidation process(Box and Behnken, 1960).Using this design methodology,we generate a set of test points.For three variables and three levels per variable,there are13test points(including the center point)as well as two more repetitions of the center point(total of15test conditions).We analyzed both the void volume as well as the apparent interlaminar shear strength(ILSS)experi-mental observations using DOE techniques with the intention of predicting the set of consolidation condi-tions that would minimize the void volume content of composites and maximize the ILSS.Scanning electron microscopy(SEM)We performed SEM of the composite specimens using an AMRAY180D scanning electron microscope,at an operating voltage of10kV.We mounted fracture surfaces of selected composites on an aluminum sur-face and sputter coated with gold in a Denton vacuum DV515evaporator.164Results and discussionInterfacial analysis studyTable1summarizes the characteristics of the panels posites withﬁber volume contents of ca.40%and an average void volume of10.5%had an average tensile modulus of14GPa and a maximum tensile strength of212MPa.Previous work on cel-luloseﬁber-reinforced cellulose ester employedﬁber acetylation in conjunction with discontinuous wood ﬁber(Glasser et al.,1999).Results from this work indicated(a)a lack of adhesion between cellulosicﬁbers and thecellulose ester matrix;and(b)thatﬁber surface acetylation resulted in a signiﬁc-ant increase in tensile performance(Table1). However,we did not see a signiﬁcant increase in the continuous lyocellﬁber system.In addition,in-spection of the fracture surfaces by SEM failed to show evidence of a signiﬁcant decrease in interfa-parative strength data for cellulosicﬁber-reinforced composites-inﬂuence ofﬁber surface modiﬁcation by acetylation1Composite properties Composite typeUnacetylated AcetylatedContinuous lyocellﬁber compositesFiber content2(%)4140V oid volume(%)138Modulus(GPa)13.3(1.1)15.2(2.2)Tensile strength3(MPa)199(22)224(28)Increase4inModulus(%)NA14.36Strength(%)NA12.66Discontinuous woodﬁber5compositesFiber content(%)4040 Modulus(GPa)0.84 1.3Tensile strength(MPa)15.933.7 Increase4inModulus(%)NA55Strength(%)NA1121Numerical values in parenthesis are standard deviations.2Determined using aminolysis(see Methods section).3Tensile testing was conducted using3replications for una-cetylated-ﬁber composites and4replications for acetylated-ﬁber composites.4Percentage strength increase due toﬁber acetylation.5Alkali-extracted steam explodedﬁbers from Yellow poplar(Liri-odendron tulipifera)as per Glasser et al.(1999).6Statistically not signiﬁcant.cial failure(ﬁber pull out)due toﬁber acetylation (Figure1).The present results seem contrary to the observa-tions made using the discontinuousﬁbers;however, we can resolve both of these sets of data by consider-ing composite mechanical theory(Agarwal and Brout-man,1990).For short-ﬁber composites,we deﬁne the ﬁber critical length(l c)as the minimumﬁber length at which the maximalﬁber stress(σmax)occurs,the breaking strength of theﬁber itself.It is related to the shear stress at theﬁber-matrix interface(τ)and the diameter of theﬁber(d)by:l cd=σmax2τ(2)Below the critical length of a short-ﬁber,the stress-carrying ability scales directly withﬁber length.In-creasing the amount of stress transfer between the matrix andﬁber effectively lowers theﬁber critical length and therefore increases the efﬁciency of the short-ﬁber reinforcement.This would serve to explain why an increase in interfacial adhesion would im-prove the tensile performance of the aforementioned short-ﬁber composite.However,when theﬁber critical length is sur-passed,the amount of stress transferred from the matrix to theﬁber remains constant at the breaking stress of theﬁber.Changes in interfacial stress transfer therefore go unnoticed in terms of composite tensile performance.This explains why we do not observe any change in tensile performance for the lyocell con-tinuousﬁber composite even after applying a chemical interfacial treatment that is known to improve mech-anical performance for the cellulose-CAB composite system.Melt consolidation studyTable2outlines the characteristics of the composite panels produced.The compositeﬁber volume content ranged from ca.52to68%(voidless basis).We ob-served the lowest void content at the consolidation condition of200◦C,81.4kPa pressure and a time of 13min(2.83%void content).We observed the highest void content at170◦C,163kPa and a time of3min (25%void content).Table2also gives the tensile modulus,ultimate strength and ultimate strain.Moduli typically ranged from18to20GPa roughly depending onﬁber content. Maximum strength values typically were centered around200MPa;however,this value is lower than the165posite tensile fracture surfaces of(A)unacetylatedﬁber composite,and(B)acetylatedﬁber composite.Table2.Consolidation conditions,composite compositions and composite propertiesTemperature Pressure Time1V f V oid Modulus Strength Strain ILSS(◦C)(kPa)(minute)(%)cont.(GPa)(MPa)(%)(MPa)(%)17081.4854818.2(3.6)210(14) 2.113.1(0.39)(1.3)170245856618.1(1.0)229(18) 1.8711.5(0.22)(2.9)1701633522510.8(2.2)120(11) 1.9210.4(1.05)(1.9)17016313581118.6(3.2)194(16) 1.7511.9(0.44)(3.1)20081.48592217.4(1.1)221(11) 1.9712.3(0.27)(1.5)20081.41360321.6(1.3)246(27) 1.7215.5(0.35)(0.9)2002453641118.4(4.7)203(26) 1.8111.6(0.14)(0.8)2002451362618.1(1.2)204(26) 1.6814.1(0.20)(1.3)200163863519.3(3.1)215(33) 1.4814.3(0.19)(0.8)200163868520.4(0.9)211(20) 1.5215.2(0.16)(1.0)200163859318.4(3.4)201(22) 1.7315.5(0.29)(1.7)23081.48641018.5(4.1)184(29) 1.1514.7(0.31)(1.5)2302458631117.3(2.5)187(19) 1.413.5(0.14)(1.6)2301633591116.4(2.2)177(31) 1.5213.4(0.35)(1.6)2301631364818.9(1.5)170(20) 1.1214.1(0.23)(0.6)1Based on time at temperature and pressure following a2-min warm-up period under vacuum.166true value due to grip effects2,voids,and the presence of stitching within the composite panels.The tensile specimen geometry is rectangular therefore grip ef-fects will tend to lower the ultimate strength of the material being tested.The stitching,present perpen-dicular to the loading direction,also tends to lower the ultimate strength of the material because it acts as a ﬂaw.We observed similar values for tensile modulus, strength,and strain in the highest quality composites produced(Seavey et al.,2001).Table2gives the observed apparent interlaminar shear strengths(ILSS)of the composites produced. The ILSS typically ranged from10to14MPa.We ob-served the highest ILSS(15.5MPa)in two composites consolidated at(a)200◦C,81.4kPa and13min,and(b)200◦C,163kPa and8min.Using the15data points for composite void volume as a function of consolidation conditions,we generated a regression model to predict void volume continuously throughout the design space.We give the model,which can account for linear effects,linear in-teractions and second order effects,in the following equation:V oid volume%=10.15+1.73T−1.69P−2.12t−−2.90TP+3.59T t+1.57P t+3.68T2−−1.32P2−3.26t2,(3) where T stands temperature,P denotes press pressure and t is the pressing time.We have normalized the input variables in this case so that they range from−1 to+1.Table3gives the P(2Tail)values,which repres-ent a probability that the parameter belongs in the model.A rule of thumb commonly used(Schmidt& Launsby1993)to determine whether or not a factor belongs within a regression model(i.e.,has an orches-trated effect)is that its P(2Tail)value must be less ing this rule,it appears that none of the input variables studied has an effect(linear,interact-ive,or second order effects)on void volume within the composite.In other words,the measured densities of the composites experienced considerable random ﬂuctuation.The P(2Tail)values for the void volume regres-sion model tell us that we cannot conﬁdently use 2Grip effects meaning the crushing effect near the grips attained at high loads.Table3.P(2Tail)values for the regression of void volumeand ILSS dataVariable P(2Tail)P(2Tail)void volume ILSSConstant0.06450T0.54090.0049P0.54880.675t0.45630.0002TP0.47050.0049Tt0.37850.5215Pt0.69000.1221T T0.38500PP0.74770.5625tt0.43870Values less than0.10indicate a signiﬁcant input variable.the model to predict changes in void volume with variations in consolidation temperature,pressure,and time.However,in passing,we note that by using the regression model,we identify a minimum void content of−0.96volume percentage at the low tem-perature(170◦C),low pressure(81.4kPa)and high time(13min)condition.We also regressed ILSS data,resulting in the following equation:ILSS(MPa)=13.7−0.550T+0.081P+0.748t++0.776TP−0.175T t−0.423P t−−1.74T2−0.164P2+1.45T2.(4)We also normalized the input variables so that they would range between−1and+1.Again,the regression model only considers linear effects,linear interaction effects and second order effects.The P(2-Tail)values are given in Table3.We apply the same rule of thumb as used before,andﬁnd that temperature(T),consolidation time(t),TP,TT and tt all seem to play an important role in determining ILSS.The P(2-Tail)values indicate that we can con-ﬁdently use the model in Equation4to predict changes in ILSS with variations in consolidation temperature, pressure,and ing the regression model for ILSS,we calculate an optimal ILSS of18.3MPa for a consolidation taking place at187◦C,81.4kPa and 13min consolidation time(Table4).This optimum suggests that there may be a pro-cessing condition that yields a better composite out-side of the design space(e.g.,lower pressure and an even longer consolidation time).However,we chose167 Figure2.Response surface for ILSS as a function of consolidation temperature and time holding consolidation pressure constant at81.4kPa.Figure3.ILSS versus composite void volume(predictions by way of Equation(3)and(4)).our design space based on the recommended CAB pro-cessing conditions as well as a desire to avoid cellulosedegradation.The design space could be widened pro-ducing a better quality composite;but we suspect thatlonger times or much higher temperatures would resultin signiﬁcant material degradation.We have precluded the need to examine theﬁbersand matrix after processing in order to detect anydegradation incurred upon processing.This is be-cause our processing conditions are similar to themanufacturer-recommended melt processing condi-tions for CAB.Furthermore,theﬁber manufacturerstates that these processing conditions do not signi-ﬁcantly degradeﬁber properties.Therefore,we feelthat by staying within our design space,we are able toavoidﬁber and/or matrix degradation.We illustrate Equation4on the ILSS responsesurface generated while keeping pressure constantat81.4kPa in Figure2.We see that the ILSS in-creases with increasing consolidation time as well asdecreases at the temperature extremes of the designspace.The optimal area(at this pressure,the apparentoptimal pressure)to operate in is evident in the contourplot:all the way to the extreme long-time conditionand moderate temperature.This is a possible reﬂectionof the limitations of using a high melt viscosity mat-rix melt,the upper limit on consolidation temperaturebeing the degradation temperature of theﬁber.The measured ILSS is negatively correlated withthe measured composite void volume(Figure3).Theprediction equations for ILSS and void volume alsoshow a negative correlation between ILSS and voidvolume.This may possibly be an indication that highvoid volumes(most likely concentrated between theplies)lead to decreases in ILSS.A limited number of composite tensile fracture sur-face samples were randomly chosen in order to revisitthe issue of interfacial adhesion between the matrixandﬁber.We depict these fracture surfaces in Figure4.As can be seen from the illustrations,ﬁber-matrixadhesion appears quite good.There are no indicationsthatﬁber surface modiﬁcation is required for adequate168Figure4.SEM images of tensile fracture surfaces.Number15shows that there is relatively littleﬁber pull-out during tensile failure,while numbers4and14show that the failure mode is cohesive failure of the matrix(rather thanﬁber-matrix delamination numbers indicate composite panel number).stress transfer to occur between theﬁber and matrix. There is relatively littleﬁber pull-out(panel15).Panel 14shows bundles ofﬁbers with extensive amounts of fractured matrix particles adhering to theﬁber surface (i.e.,cohesive failure of the matrix).In panel number 4,it is even evident that matrix spreads over theﬁber and adheres to the surface.ConclusionsWe characterized interfacial adhesion between lyocell ﬁbers and a cellulose mixed-ester matrix.Whereas woodﬁber acetylation had previously been observed to result in signiﬁcant strength gains in woodﬁber re-inforced composites,the same increase in strength was not observed in the continuous lyocell celluloseﬁber system.This suggests that interfacial stress transfer is not a limitation in this system.We then employed design of experiments in or-der to minimize composite void volume as well as maximize ILSS in the lyocell celluloseﬁber/CAB composite posites were manufactured at differing consolidation temperatures,pressures,and times.Tensile property evaluation suggested that no signiﬁcant decrease of tensile properties was exper-ienced through the use of excessive melt temperat-ures(230◦C).Furthermore,microscopic evaluation revealed very little cleanﬁber pull out during compos-ite fracture of both composites produced,suggesting relatively goodﬁber/matrix adhesion in both cases. We saw fractured matrix residues adhering strongly toﬁber surfaces,suggesting a considerable amount of cohesive matrix-failure.We optimized the properties169Table4.Optimization of ILSS and composite void volumeExperimental DOE regression2Conditions1(void vol.)T(◦C)200170P(kPa)81.481.4t(min)1313Optimized void vol.(%) 2.83−0.96Conditions(ILSS)1T(◦C)200187P(kPa)81.481.4t(min)1313Optimized ILSS(MPa)15.516.31Conditions under which optimized property values were found experimentally or predicted.2Optimized using Equation(7)and(8).of ILSS and void volume based on experimental ob-servation(pick the winner)and the use of regression techniques.The results obtained using both techniques are largely consistent(Table4);however,the lower op-timal temperatures predicted by the regression model should be approached with caution;they are limited by experimental constraints.Optimal conditions for composite consolidation appear to reside in moder-ate temperatures,low consolidation pressures and long consolidation times.Finally the optimized composites had similar per-formance on the highest quality composites produced earlier(Seavey et al.,2001).For a panel containing ca. 60vol.%ﬁber,the tensile modulus is22GPa while the tensile strength is250MPa.These panels compare favorably with Bourban et al.(1997)in which they used lyocellﬁbers with a poly(3-hydroxybutyrate)-co-poly(3-hydroxyvalerate)(PHB/V)thermoplastic matrix.They prepared unidirectional composites using powder-prepregging technology(described in detail in Seavey et al.(2001),resulting in a composite with 27vol.%ﬁber content and a modulus of11.4GPa. In addition,Bourban et al.,observed poor interfa-cial adhesion,whereas the lyocell/CAB composite system was found to possess favorable interfacial adhesion.AcknowledgementsWe are grateful to Professor Judy Rifﬂe and Mr.Mark Flynn for granting access to and providing assistance with the use of the composites laboratory facilities at Virginia Tech.This study was made possible by theﬁnancial support of the Eastman Chemical Com-pany of Kingsport,Tennessee and Acordis of Cov-entry,England.This support is acknowledged with gratitude.The Engineering Science and Mechanics Department of Virginia Tech is thanked for the use of their mechanical testing equipment;and Professor Charles E.Frazier of the Wood Science and Forest Products Department is acknowledged for the use of a gas chromatograph.ReferencesAgarwal BD,Broutman LJ.1990Analysis and Performance of Fiber composites(2nd edn).New York:Wiley.54–120.ASTM Committee D-30Subcommittee D30.041984,Apparent interlaminar shear strength of parallelﬁber composites by short-beam method.ASTM Designation D2344-84,43–45. Bourban C,Karamuk E,deFondaumiere MJ,Rufﬁeux K,Mayer J, Wintermantel E.1997Processing and characterization of a new biodegradable composite made of a PHB/V matrix and regener-ated celluloseﬁbers.J.Environ.Poly.Degrad5(3),159–166. Box GEP,Behnken DW.1960Some new three level designs for the study of quantitative variables.Technometrics2(4),455–475. Broyles NS,Chan R,Davis RM,Lesko JJ,Rifﬂe JS.1998Sizing of carbonﬁbers with aqueous solutions of poly(vinyl pyrollidone).Polymer39(12),2607–2613.Devi LU,Bhagawan SS,Thomas S.1997Mechanical properties of pineapple leafﬁber reinforced polyester composites.J.Appl.Poly.Sci64,1739–1748.Glasser WG,Taib,R,Jain RK,Kander R.1999Fiber reinforced cellulosic thermoplastic composites.J.Appl.Poly.Sci.73,1329–1340.Mansson P,Samuelsson B.1981Quantitative determination of O-acetyl and other O-acyl groups in cellulose material.Svensk Papperstidning84(3),15.Rouse BP.1965Cellulose esters,organic–plastics.In Bikales NM Gaylord NG,Mark HF,eds.Encyclopedia of Polymer Science and Technology Vol.3,New York:Wiley,356.Schmidt SR,Launsby RG,1993Understand Industrial Designed Experiments.Colorado:Air Academy Press,3-1–3-50. Seavey KC,Ghosh I,Glasser WG,2001Lyocellﬁber-reinforced cellulose ester composites.I.Manufacturing options.Cellulose 8,149–159.。

美罗凯专家杨金波教授个人简介

美罗凯专家杨金波教授个人简介杨金波博士兰州大学生命科学学院萃英特聘教授、博士生导师，肿瘤生物学与药物研究所所长。

美国克利夫兰癌症研究中心（Cleveland Cancer Research Center of USA.）首席科学家。

2001年获得中国科学院上海生物化学研究所生物化学与分子生物学专业博士学位。

历任美国Lerner Research Institute, The Cleveland Clinic Foundation, 博士后(Postdoctoral Research Fellow) (2001 - 2004 年)、研究员(Research Associate Staff) (2005 - 2006 年)、项目科学家(Project Staff) (2007 年)、客座研究员(Adjunct Staff) (2008 年)、顾问委员(Consultant Staff) (2009年- )。

主要研究方向为肿瘤相关的信号转导与分子机制，重点研究JAK-STATs、NFκB等信号转导关键分子到调控机制及其与肿瘤形成的关系、肿瘤耐药性关键分子的发现与分子机制、STATs、NFκB、IRFs 等转录因子的生物学功能、翻译后加工修饰与基因表达调控的分子机制。

承担和主持多项科技部国际合作重点项目、自然科学基金项目和省市重点项目。

论文专著(*通讯作者)1.Jing Nan, Yuping Du, Xing Chen, Qifeng Bai, Yuxin Wang, Xinxin Zhang, Ning Zhu, Jing Zhang, Jianwen Hou, Qin Wang and Jinbo Yang*. TPCA-1 is a direct dual inhibitor of STAT3 and NFκB and regresses mutant EGFR associated human non-small cell lung cancers. Molecular Cancer Therapeutics. (2014); 13(3)2.Yuxin Wang, Anette H. H. van Boxel-Dezaire, HyeonJoo Cheon, Jinbo Yang* & George R. Stark*. STAT3 activation in response to IL-6 is prolonged by the binding of IL-6 receptor to EGF receptor. Proc Natl Acad Sci USA. (2013); 110(42):16975-80.3.Xing Chen, Yuping Du, Jing nan, Xinxin Zhang, Xiaodong Qin, Yuxin Wang, Jianwen Hou, Qin Wang & Jinbo Yang*. Brevilin A, a Novel Natural Product, Inhibits Janus Kinase Activity and Blocks STAT3 Signaling in Cancer Cells. PLoS One. (2013) 8, e63697.4.Jianxin He, Jie Shi, Ximing Xu, Wenhua Zhang, Yuxin Wang, Xing Chen, Y uping Du, Ning Zhu, Jing Zhang, Qin Wang* and Jinbo Y ang*. STA T3 mutations correlated with hyper-IgE syndrome lead to blockage of IL-6/STAT3 signalling pathway. Journal of Biosciences. (2012); 37(2):243-57.5.Qifeng Bai, Yulin Shen, Xiaojun Yao, Fang Wang, Y uping Du, Qin Wang, Nengzhi Jin, Jun Hai,Tiejun Hu*, Jinbo Yang*. Modeling a New Water Channel That Allows SET9 to Dimethylate p53. PloS ONE. (2011); 6(5):e198566.Olga A. Guryanova, Qiulian Wu, Lin Cheng, Justin D. Lathia, Zhi Huang, Jinbo Yang, Jennifer MacSwords, Christine E. Eyler, Roger E. McLendon, John M. Heddleston, Weinian Shou, Dolores Hambardzumyan, Jeongwu Lee, Anita B. Hjelmeland, Andrew E. Sloan, Markus Bredel, George R. Stark, Jeremy N. Rich and Shideng Bao. Non-Receptor Tyrosine Kinase BMX Maintains Self-Renewal and Tumorigenic Potential of Glioblastoma Stem Cells by Activating STA T3. Cancer Cell. (2011); 19(4):498-511.7.Jinbo Yang*, Jing Huang, Maupali Dasgupta, Nathan Sears, Masaru Miyagi, Benlian Wang, Mark R. Chance, Xing Chen, Yuping Du, Y uxin Wang, Lizhe An, Qin Wang, Tao Lu, Xiaodong Zhang, Zhenghe Wang and George R. Stark*. Reversible methylation of promoter-bound STA T3 by histone-modifying enzymes. Proc Natl Acad Sci USA. (2010); 107(50):21499-504.8.HyeonJoo Cheon#, Jinbo Y ang# and George R. Stark. The Functions of Signal Transducers and Activators of Transcriptions 1 and 3 as Cytokine-Inducible Proteins.Journal of Interferon & Cytokine Research. (2010); 31(1):33-40. Review. (#Equal contribution)9.Jinbo Yang* & George R. Stark*. Roles of Unphosphorylated STA Ts in Signaling. Cell Research. (2008); 18(4): 443-51. Review.10.Jinbo Yang, Xudong Liao, Mukesh K. Agarwal, Laura Barnes, Philip E. Auron and George R. Stark. Unphosphorylated STAT3, Increased by gp130-Linked Cytokines, Activates Transcription by Binding to NF B. Genes & Development. (2007); 21(11):1396-408.11.Jinbo Yang, Moitreyee Chatterjee-Kishore, Susan M. Staugaitis, Hannah Nguyen, Karni Schlessinger, David E. Levy and George R. Stark. Novel Roles of Unphosphorylated STAT3 in Oncogenesis and Transcriptional Regulation. Cancer Research. (2005); 65: (3):939-47.12.Li YANG, Jin Bo YANG, Jia CHEN, Guang Yao YU, Pei ZHOU, Lei LEI, Zhen Zhen W ANG, Catherine CY CHANG, XinYing Y ANG, Ta Yuan CHANG, Bo Liang LI. Enhancement of human ACAT1 gene expression to promote the macrophage-derived foam cell formation by dexamethasone. Cell Research. (2004); 14(4): 315-23.13.Jun Zhang, Jinbo Yang, Sanjit K. Roy, Silvia Tininini, Jiadi Hu, Jacqueline F. Bromberg, Valeria Poli, George R. Stark, and Dhananjaya V. Kalvakolanu. The cell death regulator GRIM-19 is an inhibitor of signal transducer and activator of transcription 3. Proc Natl Acad Sci U SA. (2003); 100(16):9342-7.14.Moitreyee Chatterjee-Kishore, Jinbo Yang and George R. Stark. Stat-dependent gene expression without tyrosine phosphorylation. In: Signal Transducers and Activators of Transcription (STA Ts): Activation and Biology, P.B. Sehgal, D. E. Levy and T. Hirano, eds., “The STAT Book, Chapter 23, page343-354”. Kluwer Academic Publishers, printed in the Netherlands, 2003.15.Jin-Bo Yang, Zhi-Jun Duan, Wei Yao, Onel Lee, Li Yang, Xin-Ying Yang, Xia Sun, CatherineC.Y. Chang, Ta-Yuan Chang and Bo-Liang Li. Synergistic transcriptional activation of human ACAT-1 gene by IFN-γ and ATRA in THP-1 cells. J. Biol. Chem. (2001); 276 (24):20989-98.研究方向主要研究方向为肿瘤相关的信号转导与分子机制，重点研究JAK-STATs 、NFκB等信号转导关键分子到调控机制及其与肿瘤形成的关系、肿瘤耐药性关键分子的发现与分子机制、STATs、NFκB、IRFs 等转录因子的生物学功能、翻译后加工修饰与基因表达调控的分子机制。

《中国科学院院刊》参考文献着录格式及示例

《中国科学院院刊》参考文献著录格式及示例一、简要说明（1）本刊参考文献采用顺序编码制，各篇文献要按正文中引用的文献出现的先后顺序连续编码，并将序号置于方括号中，并在文后根据引文序号依次列出。

（2）多次引用同一著者的同一文献时，在正文中标注首次引用的文献序号，不应多次编号。

（3）每条文献中各项必须齐全，并要特别注意以下容易忽略的项目：论文集编者姓名、论文集书名、专著和论文集的出版城市及出版社、起止页码等。

（4）非正式出版物、互联网主页（网址）、数据库（网址）不作参考文献，放在正文中。

（5）每条文献各项信息之间均用“半角（英文）标点+空格”分隔，而每项信息内如出现标点则应与文种匹配，即中文内容用中文标点，西文内容用西文标点。

（6）西文人名一律“姓”全拼在前，“名”缩写在后，名缩写不加缩写点，姓、名中间加空。

“姓”首字母大写，其余小写；“名”只写大写首字母，两缩写名间加空。

外国人名中间有连字符的，照加，前空后不空；中国人名，中间一般不加连字符。

（7）引用多位作者合著的文章时，列前3位作者，加“等(et al)”。

（8）西文文章题目中，首词和专有名词的首字母大写，其余一律小写。

（9）西文刊名一般不缩写；如缩写须遵循ISO规范，不加缩写点且全篇所有文献均统一缩写。

（10）西文书名和论文集名中实词首字母一律大写，介词和连词为小写，但首词和4个字母以上的介词首字母应大写。

二、著录格式示例1 期刊论文序号作者. 题名. 刊名, 年, 卷(期): 起止页码.例:1 杨得庆, 隋允康, 刘正兴, 等. 应力和位移约束下连续体结构拓扑优化. 应用数学和力学, 2000, 21(1): 17-24.2 Kucheiko S, Choi J W, Kim H J, et al. Computer architecture a quantitative approach.Journal American Ceram. Soc., 1997, 80(11): 2937-2940.注意: 引用增刊论文时, 卷号后注明“(增刊)”“(Suppl)”等。

Nanoparticle Microreactor Application to Synthesis Of Titania by Thermal Decomposition

Journal of Nanoparticle Research3:309–319,2001.©2001Kluwer Academic Publishers.Printed in the Netherlands.Nanoparticle microreactor:Application to synthesis of titania bythermal decomposition of titanium tetraisopropoxideK.Y.Park∗∗,M.Ullmann,Y.J.Suh and S.K.Friedlander∗Department of Chemical Engineering,University of California,Los Angeles,CA90095,USA∗Author for correspondence(Tel.:3108252206;Fax:3102064107;E-mail:skf@)Received5January2001;accepted in revised form25May2001Key words:nanoparticle microreactor,gas phase synthesis,nucleation,TiO2,titanium tetraisopropoxide AbstractThe nanoparticle microreactor(NPMR)is a new concept that we have introduced to describe a very small-scale system capable of converting an aerosol precursor to solid particles.The liquid precursor of about1µl is injected by a syringe through a septum into a tubular evaporator of1.0cm3in volume with stopcocks at both ends.The evaporator has been preheated by a heating tape to a temperature sufﬁciently high for vaporization to occur in half a minute.By opening the stopcocks,the vaporized precursor is transported by a carrier gas stream into a quartz tube which is mounted along the axis of a tubular furnace.The nanoparticle aggregates produced in the reactor are sampled by deposition on an electron micrograph grid at the reactor exit.The NPMR was appliedﬁrst to the synthesis of TiO2particles by thermal decomposition of titanium tetraisopropoxide(TTIP)in a nitrogen carrier gas,with TTIP concentrations varying from1.0to7.0mol%or2.35×10−6to1.65×10−5in TiO2volume loading, and decomposition temperatures from300◦C to1000◦C.Studies were made with a2mm reaction tube and a4mm tube with sheath gas.With the2mm tube,a considerable fraction of the TTIP precursor was consumed at the wall by surface reaction,resulting in very small particles.With the4mm tube,the primary particle size was comparable to that reported in the literature for steadyﬂow experiments using a22.2mm tube.Primary particle sizes ranged from200to400nm.Depending on TTIP concentration and reactor temperature,the particles exhibited a bimodal size distribution,probably due to a two-stage nucleation.A fourfold increase in the gasﬂow rate had little effect on particle size,indicating that particle growth ended early,within one-fourth the tube length.Residence time in the reactor was between0.35and1.4s,and total run time about1min.The NPMR has potential for rapid assem-bly of large databases and is adaptable to combinatorial discovery of nanoparticles with novel properties.Design requirements for an‘ideal’aerosol microreactor are discussed brieﬂy.IntroductionGas phase synthesis of nanoparticles,in which a pre-cursor is vaporized and reacts to form solid particles,is of interest because of its simplicity and ability to gen-erate dry particles directly,compared to liquid phase synthesis.Carbon black,fumed silica and titania are important examples of nanoparticles produced com-mercially using gas phase synthesis.At the present ∗∗On leave from Kongju National University,Kongju,Korea time,considerable effort is being made to extend its application to the production of advanced powdered materials for use as catalysts,electronic devices and ductile ceramics.Many lab-scale studies have been made to demonstrate novel methods of particle synthe-sis or elucidate the mechanisms of particle formation, using a variety of reactors:ﬂame,electrically heated, laser or plasma reactors(Pratsinis&Kodas,1993). These studies have been made with a continuous sup-ply of precursor vapor to the reactor;in most cases,a carrier gas was bubbled through the liquid precursor.310Figure 1.Concept of nanoparticle microreactor (precursor vapor is indicated in gray).This method provides reliable data in steady state oper-ation.However,it is less satisfactory for very small volumes of precursor and may be too time-consuming for rapid searching of product properties for new mate-rials and varying process conditions.The search can be made more efﬁcient by using small-scale reactors with short run time.An idea is to have a small volume of precursor vapor converted to particles,ideally under conditions of uniform temperature,concentration and residence time.In the present work,a nanoparticle microreactor (NPMR)was developed which can accept a micro-liter of precursor and complete a run within a minute.Figure 1shows the concept of the microreactor.The liquid precursor is injected into an evaporator,1cm 3in volume and vaporized.Then,the precursor vapor is transported by a carrier gas to the reactor as a bolus,similar to a pulse injection.The reaction volume of the vapor is as small as 1cm 3and the reaction time is only a few seconds.Because of the small system size,NPMR operating conditions can easily and quickly be varied to produce large databases relating product prop-erties (for example,particle size and crystal structure),to precursor properties and process conditions.These databases should be useful for discovery of nanopar-ticles with novel properties.This is an application of the combinatorial approach,which the pharmaceuti-cal industry uses for the rapid synthesis and screen-ing of new drug candidates (Dagani,1999).Another advantage of the NPMR is that chemical consumption is smaller,producing fewer pollutants.The NPMR was tested on the synthesis of TiO 2par-ticles from titanium tetraisopropoxide (TTIP)over the reaction temperature from 300◦C to 1000◦C,using two reaction tubes:a simple 2mm tube and a 4mm tubewith sheath gas entry.Earlier studies of TiO 2from TTIP using tubular reactors have been made by Kirkbir and Komiyama (1987),Okuyama et al.(1986)and Jang and Friedlander (1998).In these studies,however,the reaction tubes were an order of magnitude larger,13–22.2mm in diameter,and the precursor was trans-ported to the reactor continuously by a carrier gas bub-bled through a bottle containing liquid TTIP.Another difference is in the concentration of TTIP;in the present study concentration ranged from 1.0to 7.0mol%,much higher than those of previous studies ranging from 0.00136to 1.34mol%.A concentration of 7.0mol%is in the range typical of silica ﬂame synthesis in indus-trial reactors (Ulrich,1971);data in commercial reac-tors for TiO 2were not available to us.The production of TiO 2by thermal decomposition of TTIP was exper-imentally validated earlier at a temperature higher than 250◦C (Komiyama et al.,1984).We assume that the solid decomposition product of the present study made at 300–1000◦C is TiO 2.In the present paper,the particle size was chosen for discussion,out of various product properties.The effects of tube size,TTIP concentration,reactor temperature and residence time on the primary particle size were investigated.The particle sizes were compared with those of Kirkbir and Komiyama (1987),who bubbled helium through the liquid precursor and passed the mixed vapors through a 22.2mm reaction tube.Our goal was to study the effect of scale and batch vs.continuous operation on product properties.Experimental sectionNanoparticle microreactor systemFigure 2shows a schematic diagram of the microreac-tor system which consists of an oxygen trap (Hewlett-Packard,Model HP3150-0528),a drying column (Hammond,Model 27066)a carrier gas preheater,an evaporator,a tubular furnace (Thermolyne,Model 21100)and a particle collector.The preheater is a pyrex cylinder wrapped with a heating coil,with a volume of 100cm 3selected to give a residence time of 3min at the carrier gas rate of 34cm 3/min.The carrier gas is heated by the preheater to a temperature higher by about 20◦C than the evaporation temperature to protect the vapor generated in the evaporator from being condensed by the incoming carrier gas.The evaporator is a pyrex tube with stopcocks at both ends,measuring 0.5cm I.D.and 5cm long.A septum is placed in the center for injection of liquid precursor by a syringe.The evaporator was311Figure 2.Schematic drawing of nanoparticle microreactorsystem.Figure 3.Two types of reaction tube used in the present study.wrapped with a heating coil,and the temperature mon-itored by a thermocouple inserted through the septum.The evaporator was heated to a predetermined temper-ature before evaporation began.To start the evapora-tion,the two stopcocks were closed and the precursor injected by a syringe.By opening the stopcocks simul-taneously,a bolus of the precursor vapor is transported to the reactor by the carrier gas.During evaporation,the carrier gas bypasses the evaporator through the three-way stopcock on the right hand side.The reactor is a quartz tube 45cm long,mounted along the axis of an electric furnace.Figure 3shows the two reaction tubes used in our study.In the case of the 2mm tube,one end is connected to the evaporator and the other end to the particle collector by O-ring ball joints.The distance from the evaporator outlet to the furnace inlet is about 10cm.For the 4mm tube withsheath gas,a 1/4-inch stainless steel union cross was added for the introduction of sheath gas,between the evaporator and the furnace (Figure 4).The sheath gas preheated in a heating pipe comes from the bottom of the union cross,turns to the right and passes through a 80mesh screen,and enters the 4mm tube to form a sheath layer outside the TTIP stream leaving the 2mm inner tube.The union cross is wrapped with a heating tape and a thermocouple is installed to measure the sheath gas temperature.At the reactor exit,a transmission electron microscopy (TEM)grid about 3mm in diameter was mounted on a stainless steel tube and inserted into the center of the aerosol stream.Particle deposition took place probably by diffusion to the surface of the grid from the gas ﬂowing along the axis of the reactor tube.After completion of a run (about 1min)the grid holding tube was removed through an O-ring.Experimental procedureNitrogen (99.99%)was passed through the oxygen trap and dryer in series and split into two streams:one to the carrier gas preheater and the other to the sheath gas preheater.The ﬂow rate of each stream was mea-sured by a rotameter before the preheater.The sheath gas ﬂow rate was three times the carrier gas ﬂow rate to keep the linear velocity of each stream the same at the entrance to the reaction tube.The carrier gas was preheated to 170◦C in the preheater and passed through the evaporator with the stopcocks open for about312Figure 4.Illustration of sheath gas entry section.Inside the union cross,a 2mm stainless steel tube,64mm in length and 0.2mm in thickness,is installed extending into the 4mm reaction tube by 25mm.30min until the evaporator was purged and heated to 152◦C,10◦C higher than the saturation temperature at the maximum TTIP concentration of 7mol%.Then,the stopcocks were closed and a predetermined vol-ume of TTIP was injected into the evaporator by a 1µl syringe (SGE,Model SG-000500).The TTIP was of ultra high purity (99.999%,Sigma-Aldrich).The vol-ume of TTIP required for a concentration of 7mol%in the reactor gas ﬂow was 0.7µl.The concentration was controlled by the injection volume of TTIP.The time to vaporize the TTIP was estimated to be 53s,assuming that the 1mm TTIP droplet remaining suspended from the tip of the syringe during the entire period of evaporation.In reality,the drop may fall to the evaporator wall during heating,due to the decrease of surface tension.Based on the estimate,the residence time in the evaporator was varied from 5to 30and 60s,with the reactor temperature at 700◦C.Particle size was smaller with a residence time of 5s indicating the time is too short for complete vaporization.There was no difference in particle size for residence times between 30and 60s;therefore,the evaporation time was kept at 30s.The stopcocks were opened immediately after evap-oration to transport the TTIP vapor to the reactor which had already been heated to a predetermined temperature.The power to the heating tape wrap-ping the transport line was controlled to maintain the vapor temperature at about 170◦C,well above theTable 1.Operating conditions Operating parameterFor 2mm For 4mm tube tube with sheath gas TTIP conc.(mol%)7.0 1.0–7.0N 2carrier ﬂow rate 34.017.0–68.0(cm 3/min)N 2sheath ﬂow rate0.51.0–204.0(cm 3/min)Space time at STP (s) 2.21.1–4.4Reactor temp.(◦C)500–1000300–700Evaporator volume:1.0cm 3Evaporator temperature:152◦C Evaporation time:30sOperating pressure:101.3kPasaturation temperature.The operating conditions for the experiments are shown in Table 1.At the exit from the reactor,the particles were col-lected on the carbon ﬁlm coating a 200mesh nickel grid (Electron Microscopy Science,Model CF200-Ni),and examined by transmission electron microscopy (JEOL,Model JEM 100CX).The particles were present both as individual primary particles and aggregates.From an image obtained by scanning the TEM micrograph,70–200primary particles were selected and their sizes were determined to calculate the number average and Sauter mean diameters using a computer program in which the number of pixels occupied by a particle is counted and converted into a diameter.The Sauter mean313diameter,D 32is deﬁned asN i d 3i / N i d 2i ,where N i is the number of particles of diameter d i .It was used earlier by Kirkbir and Komiyama (1987)and employed for comparison purposes.Results and discussion Two millimeter reaction tubeFigure 5shows the change in primary particle size for the 2mm reaction tube,as the reactor tempera-ture was increased from 500◦C to 700◦C and 1000◦C.A constant temperature zone about 30cm long was maintained in the reaction tube.The SautermeanFigure 5.TEM images of TiO 2particles with 2mm reaction tube (N 2ﬂow:34cm 3/min;TTIP concentration:7mol%).D 32is the Sauter mean primary particle diameter.Most of the TTIP conver-sion took place on the reactor wall.diameter of the primary particles increased with reactor temperature from 9.0nm at 500◦C to 20.6nm at 700◦C and 31.7nm at 1000◦pared to those of Kirkbir and Komiyama (1987),120nm at 500◦C and 65nm at 700◦C,our primary particle size is much smaller even though our TTIP concentration was 10times higher,and the effect of the temperature on particle size is in the opposite direction.We set out to determine the cause of the discrepancy.The TTIP concentration,initially 7mol%in the evaporator,decreases due to dispersion as the bolus moves from the evaporator to the reactor.By a rough calculation,the dispersion must have affected the parti-cle size to some extent,but was probably not the critical factor causing the discrepancy.After the run,inspec-tion of the wall of the 2mm tube showed a zone coated with what was probably TiO 2.At a reactor tempera-ture of 500◦C,a coated zone 2.2cm in length formed starting at 1.2cm from the furnace inlet (Figure 6).The length of coated zone was decreased to 0.7cm by an increase of the reactor temperature to 700◦C.A considerable portion of the TTIP vapor admitted to the reaction tube probably reacted at the wall,reduc-ing the amount of TTIP available for particle forma-tion.This may be the main reason why our primary particle sizes with the 2mm reaction tube were much smaller than those of the earlier studies.As the tem-perature increased,the rate of homogeneous reaction in the gas phase increased,and the TTIP loss to the wall decreased,leading to an increase in particlesize.Figure 6.Temperature proﬁle and location of coated zones with 2mm reaction tube.314The coalescence of colliding particles may also have played a role in the particle size increase with the tem-perature increase to 1000◦C;the collision-coalescence mechanism described earlier by our group (Windeler et al.,1997)predicts signiﬁcant coalescence at this tem-perature.At a reaction temperature of 1000◦C,another zone coated with black carbonaceous materials formed,probably by decomposition of propylene,a byproduct of TTIP decomposition.The leaf-like features seen in the TEM micrograph at 1000◦C (Figure 5c)may be the carbonaceous materials.Four millimeter reaction tube with sheath gas To reduce the surface-reaction effect,the 2mm reac-tion tube was replaced by a 4mm tube with sheath gas entry.As shown in Figure 3,sheath nitrogenwasFigure 7.Effect of reactor temperature on particle morphology for 4mm reaction tube with sheath gas (N 2carrier gas:34cm 3/min;TTIP concentration:7mol%).introduced to protect the wall from being coated by surface reaction.The carrier gas ﬂow rate was kept the same as with the 2mm tube.The sheath gas rate was controlled such that its average linear velocity was the same as that of the TTIP stream leaving the inner 2mm tube.After a run,no coated zone was seen.After a few more runs,a coated zone became visible indicating that the surface reaction at the wall was not eliminated completely.Kirkbir and Komiyama (1987)reported earlier that a coated zone formed even with a much larger tube,22mm in diameter,in the absence of sheath gas.The precursor loss to some extent by surface reaction seems to be unavoidable in laboratory-scale reactors.In the present study,it was difﬁcult to measure the loss because of the small volume of precursor admitted to the reactor.Figure 7shows the TEM micrographs of parti-cles produced with reactor temperatures varying from315400◦C to 1000◦C,holding the TTIP concentration at 7mol%and the carrier gas rate at 34cm 3/min.At tem-peratures higher than 500◦C,the particle size showed a bimodal distribution:one group of larger spheri-cal particles,250–650nm in diameter and the other group of chain-like aggregates composed of 15–20nm particles.At 400◦C,however,those chain aggregates disappeared,indicating that the aggregates were gen-erated between 400◦C and 500◦C.The cracks seen around the particles at 400◦C (Figure 7a)formed in a few seconds after the TEM grid was placed under an illumination of electron beam for exam-ination.Some unconsolidated materials may have deposited around the particles and undergone a struc-tural change under the beam to develop a stress result-ing in the formation of the cracks.Figure 8shows the effect of TTIP concentration on particle mor-phology.The concentration was varied from 7to 3.5and 1.0mol%,keeping the reactortemperatureFigure 8.Effect of TTIP concentration on particle morphology for 4mm reaction tube with sheath gas (N 2carrier gas:34cm 3/min;Reactor temperature:700◦C).constant at 700◦C and the carrier gas ﬂow rate at 34cm 3/min.As the concentration was reduced from 7to 3.5mol%,the length and the number of the aggre-gates decreased markedly.The chain aggregates ﬁnally disappeared as the concentration was further reduced to 1mol%.The bimodal size distribution has not been reported in previous studies,which were performed at TTIP concentrations much lower than in the present study and with larger reaction tubes.To elucidate the cause of the bimodal distribution,it may be necessary to understand the mechanism by which the decompo-sition occurs.The overall reaction can be repre-sented by Ti (OC 3H 7)4=TiO 2+4C 3H 6+2H 2O.However,the reaction mechanism is not well known yet.By analogy to the mechanism of tetraethoxysi-lane (TEOS)decomposition (Satake et al.,1996),we assume that the decomposition of TTIP proceeds as follows by (1)β-hydride elimination of propene and316(2)polymerization:(CH 3CHCH 3O )3Ti (OCH 3CHCH 3)→(CH 3CHCH 3O )3Ti (OH )+CH 2CHCH 3(1)(CH 3CHCH 3O )3Ti (OH )+(CH 3CHCH 3O )Ti (OCH 3CHCH 3)3→(CH 3CHCH 3O )3Ti–O–Ti (OCH 3CHCH 3)3+CH 3CH (OH )CH 3(2)By successive β-hydride elimination and polymeriza-tion,the dimeric species in Eq.(2)continues to growwith its vapor pressure decreasing,and eventually leads to a stable particle or a nucleus when the vapor pressure drops below a certain level.The nucleus may not be pure TiO 2,but contain carbon and hydrogen to some extent.Once nuclei are formed,they grow by surface reaction of TTIP vapor and scavenging of the clus-ters and by coagulation as well.During the growth,residual carbon and hydrogen are removed by further decomposition to make TiO 2.The isopropyl alcohol in Eq.(2)is dehydrated to produce propene and water.TiO 2is known to catalyze the dehydration (Carrizosa &Munuera,1977).TTIP vapor decomposes at temperatures above 250◦C (Fictorie et al.,1994).Komiyama et al.(1984)reported a similar decomposition temperature.Figure 9shows the temperature proﬁle measured at a reactor set point of 500◦C,over the transient zone where the tem-perature is on the increase.The approximate concentra-tion proﬁle shown in the ﬁgure illustrates the discussion that follows.The TTIP vapor admitted at 200◦C to the 4mm tube starts to be heated and decomposition begins.Nucleation occurs when the gas is heated to a sufﬁciently high temperature.This temperatureisFigure 9.Two-stage nucleation in furnace.not known,but may be between 250◦C and 400◦C.The nuclei,then,grow as described above.When the vapor temperature reaches 400◦C,further nucleation occurs provided that a sufﬁcient amount of TTIP vapor remains unconsumed.The larger particles in Figures 7and 8may have originated from the ﬁrst nucleation and the smaller particles composing the chain aggregates from the second nucleation.The second nucleation rate may be faster than the ﬁrst because of the higher temperature generating more nuclei resulting in smaller primary particles.At the TTIP concentration of 1mol%and the reactor temperature of 700◦C (Figure 8a),the second nucle-ation did not occur because the amount of TTIP left after the ﬁrst nucleation and subsequent growth was not enough to generate new particles.At the reac-tor temperature of 400◦C and the TTIP concentration of 7mol%(Figure 7a),the second nucleation did not take place either because the temperature was too low,even though the TTIP concentration was high enough.In the synthesis of silicon from silane (SiH 4),Alam and Flagan (1986)reported that undesired nucleation could be avoided by controlling the temperature pro-ﬁle in the reactor.Experimental evidence that the heat-ing rate in the early stages affected particle size can also be found in the work of Park et al.(1991)on the generation of iron particles by hydrogen reduc-tion of FeCl 2vapor.Thus,the temperature proﬁle in the transient zone must be a factor in controlling the particlesize.Figure 10.Axial temperature proﬁles with varying carrier gas ﬂow rates at 700◦C for 4mm reaction tube with sheath gas.317 Figure11.Effect of carrier gasﬂow rate on particle size for4mm reaction tube with sheath gas(reactor temperature:700◦C;TTIP concentration:1mol%).The residence time,τ(reactor volume/volumetricﬂow rate at700◦C),varied from0.35to1.4s.There was no effect of residence time on primary particle size.Holding the reactor temperature at700◦C and the TTIP concentration at1mol%,the carrier gasﬂow rate was varied from17to68cm3/min,while main-taining the ratio of sheath to carrier gas rates at3.0. The temperature proﬁles with varying gasﬂow rates are shown in Figure10.There exist some temper-ature differences in the transient zone,between the three gasﬂow rates,but nearly no difference in the isothermal zone.Figure11shows that the particle size is insensitive to the variation of the gas rate or the increase of the residence time by a factor of four. This implies that the particle growth was completed within one-fourth of the tube length.A similar result was reported by Kirkbir and Komiyama(1987)who found that the variation of the residence time in the range3.8–10.2s had no effect on the particle diame-ter of TiO2produced from TTIP at300◦C.In contrast, Akhtar et al.(1991)reported that for TiO2particles generated by oxidation of TiCl4in a tubular reactor, particle size increased with increasing residence time at a reactor temperature of1123◦C.They attributed the size increase to an increase in time for coagulation. The reactor temperature of the present study may be too low for coalescence to occur;once the primary par-ticles formed,the residence time had little effect on their size.Comparison with results from a steadyﬂowlarger scale systemA principal goal of our study was to compare the microreactor data with results for larger scale systems. For this purpose,the primary particle sizes were com-pared with results of Kirkbir and Komiyama(1987) whose tube size was larger,22.2mm in diameter,with the precursor vapor supplied steadily to the reactor by bubbling helium through a precursor reservoir. Figure12shows the comparison for TTIP concentra-tions near1.0mol%with reactor temperatures ranging from300◦C to700◦C.The concentration indicated318parison of primary particle size for the NPMR and a larger scale system.for our data is the one at the evaporator.The actual concentration of TTIP in the reaction zone must be lower because the TTIP vapor disperses during trans-port from the evaporator to the reactor and diffuses to the sheath gas layer,on entering the reactor.At present,no quantitative information is available on the concentration decay.Figure12shows that our particle sizes were com-parable to theﬂow reactor data and the dependence of particle size on the temperature was similar,the parti-cle size decreasing with increasing temperature.In the gas-phase synthesis of TiO2from TTIP or TiCl4,some investigators(Suyama&Kato,1976;Jang&Jeong, 1995)reported a similar decrease in particle diame-ter with increasing temperature,while other studies (Formenti et al.,1972;Akhtar et al.,1991)showed an increase.By examining the operating temperatures at which those data were obtained,the transition temper-ature was near1100◦C.At temperatures below1100◦C, the particle size seems to be controlled by the nucle-ation rate because the temperature is probably too low for signiﬁcant coalescence of aggregates.Above 1100◦C,coalescence becomes dominant,and the par-ticle size increases with increasing temperature.Sum-marizing,an important factor in the scaling of these systems is the time–temperature history as well as the concentration of the precursor vapor;if these features are similar for different aerosol reactors,the particle size of the product should be similar.Summary and conclusionsIn aerosol reactor design,the main goal is to produce particles with desired properties–primary particle size,aggregate size,crystalline state and primary par-ticle bond energies.It is generally not possible to predict particle properties fromﬁrst principles alone, and pilot scale studies and modeling are important in scale-up.We have introduced the concept of a small-scale‘microreactor’capable of generating particle samples on TEM grids which are easily examined for particle properties.To test this concept,we designed a miniaturized reac-tor capable of producing TiO2nanoparticles from about 1µl of TTIP in a1min run time.With a2mm reac-tion tube,a considerable fraction of the TTIP was con-sumed at the wall by surface reaction,resulting in very small particles.For a4mm tube with sheath gas,the surface reaction was reduced and the particle size was comparable to that reported earlier by other investiga-tors for steadyﬂow experiments with a22.2mm tube. Increasing the gasﬂow rate by four times had little effect on particle size,implying that particle growth had been completed within one-fourth of the tube length, also in agreement with previous work using a larger reactor.Depending on TTIP concentration and reactor temperature,particles showed a bimodal size distribu-tion probably due to a two-stage nucleation.The microreactor has potential for the rapid assem-bly of large databases and is adaptable to combinato-rial discovery of nanoparticles with novel properties. Results compare well over some ranges with a larger scale reactor.Still much work remains to be done to make the microreactor a reliable tool for predicting par-ticle properties of larger scale systems.Accounting for axial dispersion requires further study.Rapid analysis of TEM grid particle deposits is another challenge. AcknowledgementsThis research was supported by the Korea Research Foundation Program for Support for Faculty Research Abroad and by NSF Grant#CTS9911133. S.K.Friedlander is Parsons Professor of Chemical Engineering.ReferencesAkhtar K.M.,Y.Xiong&S.E.Pratsinis,1991.Vapor synthesis of titania powder by titanium tetrachloride oxidation.AIChE J. 37,1561–1570.。

文献调查法案例

文献调查法案例篇一：文献信息调研案例文献信息调研案例课题：微生物在污水处理中的应用方面的研究课题要求：利用相关数据库及网上资源，查找相关文献和信息，在获得主要相关文献信息的基础上，写出反映当前国内外发展情况的综述报告。

1.课题背景知识、概念分析与文献信息调研的基本思路通过全文期刊网、网络搜索引擎等工具，获得以下背景知识：微生物处理污水是在污水里投放大量有效微生物菌种，促使水体本身快速形成一个平衡的生态系统，其中不仅有分解者生物、生产者生物、还有消费者生物，三者分工协作，对污水中的污染物进行更有效的处理与利用，并由此可形成许多条食物链，构成纵横交错的食物网生态系统。

如果在各营养级之间保持适宜的数量比和能量比，就可建立良好稳定的生态平衡系统。

当一定量的污水进入这种生态体系中，其中的有机污染物不仅被细菌和真菌降解净化，而其降解的最终产物，一些无机化合物作为碳源、氮源和磷源，以太阳能为初始能源，参与食物网中的新陈代谢过程，并从低营养级到高营养级逐级迁移转化，最后转变成水生作物、鱼、虾、蚌、鹅、鸭等高级的生命体产物,而且通过人们的不断的取走和加入的措施来保持水体的综合生态平衡，增加水景的美观自然，达到防治水体的富营养化的目的。

由有关专业知识可知，本课题涉及的概念主要有“微生物”、“处理”、“污水”及其它们得组合。

根据课题调研要求，计划在理解课题基本内容的基础上，选择使用有关的网络数据库和INTERNET，进而获取主要文献信息的原文，阅读消化，写成综述报告。

2.检索工具以及检索途径的选择根据课题分析，选择的网络数据库有：中国期刊全文数据库、EBSCO，选择的网上信息源有baidu本课题以综合课题当前发展状况为目的，希望获得结果的特点是“全”，即不能遗漏主要相关文献信息。

因此，检索途径拟以关键词途径为主，辅以分类方法。

为了保证做到尽可能的查全，在获得初步检索结果后，以获得主要相关作者姓名、分类号等线索，从作者途径、分类途径在反复搜寻一次。

开关电源经典书籍推荐

开关电源经典书籍推荐Power Supply Cookbook, Marty Brown, EDN Series, 2001.本书作者Marty Brown任职On Semiconductor (Motorola)多年,具有多年开关式电源供应器设计之实务经验,本书可以说是他以工程师的观点,以实务经验为出发点所著作的一本精简扼要的设计参考书籍,全书仅230余页.本书重点主要在第三章:PWM Switching PowerSupplies说明传统脉宽调变转换器的设计方法;与第四章:Waveshaping Techniques说明新型的谐振式转换器设计方法.本书的优点是掌握重点,可以快速的建立系统的设计观念,缺点是未提供设计方程式推导说明,初学者不易了解其设计概念.Switching Power Supply Design, Edited by: Abraham I.Pressman, McGraw Hill, 2nd Ed., Nov. 1997.本书作者Abraham I. Pressman可以说是开关式电源设计祖师级开创大师早自1977年即着有『Switching and Linear Power Supply,Power Converter Design』一书,是早期电源设计从业人员重要的参考书籍.本书是作者20年后再次出版的一本SPS设计专业书籍,全书包含了十七章近700页,针对电源设计的专门议题都有重点的说明,读者可以选择有兴趣的章节阅读,是一本很好的设计百科工具书.[缺图]交换式电源技术手册, 原著:原田耕介, 译者:陈连春, 建兴出版社, 1997年10月.本书是原田耕介先生自1990年~1993年间在日本『电子技术』杂志连载关于电源供应器技术解说相关文章所汇整而成的一本着作,本书汇集了四十余位专家学者在开关式电源设计的专业说明,1997年由陈连村先生翻译中文本,本书目前已更新至第二版.本书的特色是非常实际,直接提供设计相关信息与实例说明,都是从事电源多年工作经验的累积,是从事电源设计工程师必读的参考书.Switching Power Supply Design & Optimization, SanjayaManiktala, McGraw Hill, May 2004.本书作者任职于美商国家半导体公司(National Semiconductor)主任工程师,具有多年电源设计之实务经验.电源设计是一个整合理论与实务的最佳化过程,在这个复杂的最佳化过程当中,有许多需要进行试试看的选择,而这些选择又不纯然只是试试看,是基于经验与理论判断的试试看,有时也需要一些灵机一动的想法,也就是这些困难与迷惑成就了电源设计引人入胜之处,许许多多的工程师置身其间,获得难以言明的乐趣.本书作者选择了『最佳化』为书名之关键字,有兴趣的读者可一窥实务工程师观点的最佳化思路历程.Switch-Mode Power Supply Simulation: Designing with SPICE3, Steven M. Sandler, McGraw-Hill Professional; 1st Ed., Nov.11, 2005.电源供应器太复杂了,它的复杂一方面来自开关瞬间变化所引发的电路与元件的高频动态特性,另一方面也源自于元件的非线性特性,更遑论因结构所导致的散热,因电路布局所引发的电磁干扰,以及负载变化所造成的非线性动态响应等等,因此对电源问题接触的愈为深刻,可能导致对计算机模拟的愈发怀疑?『为何要做模拟?哪有那么多时间?』经常是实务工程师心中的疑问?本书从磁性元件,特别是多组输出变压器的相互耦合开始,建立其等效电路模型,进而以EMI 滤波器设计为对象,说明以SPICE模拟为导向的设计与分析方法,本书或可以作为开关式电源供应器的理论建模与实务应用之间的一个桥梁.Practical Computer Analysis of Switch Mode Power Supplies,Johnny C. Bennett, CRC Press, July 27, 2005.本书是一本着重于SPICE计算机模拟的电源设计参考书,作者以自身多年电源设计的实务经验为基础,说明了以小信号模型为基础的开关式电源转换器回路补偿设计方法,书中列举了多种常用电源转换电路的SPICE小信号等效电路模型及其模拟之频率响应,对DC-DC转换器控制回路设计有兴趣的读者可参考本书.Switch-Mode Power Supply SPICE Cookbook, ChristopheBasso, McGraw-Hill, March 19, 2001.本书作者任职于法国On Semiconductor但任电源应用工程师,本书以SPICE为模拟工具,针对各种基本的开馆转换器电路架构进行了模拟实例说明,是一本很好的范例参考书,有兴趣利用SPICE进行开关式电源学习与设计的同好,这是一本容易入手的参考书.Switch-Mode Power Supplies - SPICE Simulations andPractical Designs, Christophe Basso, McGraw-Hill, Feb. 1,2008.本书作者任职于法国On Semiconductor但任电源应用工程师,本书试图结合SPICE的理论模拟与实务设计,藉由模拟找出实务设计的关键,由于能得到On-Semi的工程支援,作者在书中所列举的模拟实例电路已能完全以实际应用电路为主,并藉由所建立的PWM IC行为模型(behavior model)进行系统层次的模拟,可以提供电源系统设计工程师与电源控制IC设计工程师在实作之前具体掌握电源系统的动态响应.对乐于尝试以SPICE进行开关式电源设计者而言,是一本必备的书籍.Fundamentals of Power Electronics Robert W. Erickson andDragan Maksimovic, Kluwer Academic Publishers, February2001.本书两位作者均毕业于加州理工学院,师承大名鼎鼎的S. Cuk与R.D. Middlebrook,Prof. Cuk发明了著名的Cuk Converter,也是Prof. Middlebrook的学生,本书可说是加州理工学院在电力电子领域学术发展一脉相承的具体表现.本书厚达近900页,内容充实、说理分明是其优点.要建立电力电子专业领域的理论基础,这是一本最好的教课书.本书作者所在的科罗拉多大学以本书开授了三门相关课程,由此可见本书内容之丰富.对从事电源设计的工程师而言,本书距离实用最遥远,但却是最重要的理论基础,读通此书,辅以实务经验,可成专业.Fundamentals of Power Electronics with MATLAB, RandallShaffer and Charles River Media, 1st Ed., Aug. 2006.MATLAB/Simulink是许多学生在校时最常使用的软件,但要应用MATLAB于电源设计,却不是件容易的工作,主要关键是必须了解设计规格、建立设计流程、推导设计方程式.Simulink的模拟环境提供了一个以电力电子为应用对象,含电源与马达控制的模拟软件PowerBlock Set,可以图形化的方式定义马达与电源的模拟电路图,再进行模拟分析.本书提供了一些以状态方程式为主的开关式电源转换器应用实例,可以作为建立以MATLAB为设计平台的开关式电源供应器设计软件.MathCAD数学入门导引(附光盘), 杨国隆、熊高生, 松岗出版社, 2008年02月25日.Excel可能是许多专业电源设计工程师最常使用的软件,设计者可以建立专属的设计流程、设计方程式,根据规格可以快速决定适当的元件参数值.但是Excel不易阅读,难以达到设计承传的效果,MathCAD是一个可以结合文字说明、方程式定义、交互式在线计算、计算结果图形化、技术文件排版、转换成Word格式的doc档等等功能,可以说是设计文件化的最佳软件,也逐渐成为许多电源系统与IC设计公司的标准设计软件.是从事专业电源设计工程师的必学软件.目前市面上尚未见到以电源设计为应用的MathCAD专业书籍,本书主要在于介绍MathCAD的基本功能,是可以参考的MathCAD使用入门书籍.。

数据库简介KluwerAcademicPublisher是荷兰具有国际性声誉的学术

二、数据库检索方法
1、检索主页面：IP登录进入主页面
检索
刊名或学科浏览
二、数据库检索方法
2、检索方法
• 期刊浏览 • 简单查询 • 复杂查询
二、数据库检索方法
（1）期刊浏览：通过刊名首字母或学科主题浏览期刊
两种方式浏览期刊（1）期刊名称A-Z （2）学科主题
二、数据库检索方法
（2)简单查询：输入一个检索条件快速找到需要的文献
输入检索词并选择检索字段进行快速检索
选择检索时间及显示方式
二、数据库检索方法
（3）复杂查询：输入一个或多个检索条件
字段选择
限定检索时间及学科类别、文献种类
限定检索的显示条件
二、数据库检索方法
（3）复杂查询：作者字段或作者关键词的检索
1.姓氏在前，名字在后，中间加逗号间隔。如：White, Robert 表示检索姓White，名Robert的作者。 2.输入一个字, 如Robert, 只要姓名中出现Robert, 无论是姓还是名, 都检索出来。 3.输入两个或以上的字, 中间不加逗号: 如Robert White, 只要姓名中Robert 和 White同时出现, 无论姓Robert还是姓White, 都检索出来。 4.复姓及有前缀的姓名，中间不加逗号，如：J. P. van der Meer 只要每个字同时出现在姓名里，即检索出来。 5.复姓及有前缀的姓名，中间加逗号, 如：van der Meer ，J. P. 确定为Van der Meer为姓，J. P. 为名。 6.姓名中间允许加*表示截断，如：输入M* Smith或Smith, M*, 将把Mark Smith, Michcale Smith, M. L. Smith检索出来。

政治学主要外文期刊简介

政治学主要英文期刊简介1、刊名称American Political Science Review, with PS: Political Science & Politics.ISSN: 0003-0554创刊年:1906出版期次4/yr. 开本:21.5x15.5 页数:300 目录价:154/USD出版机构American Political Science Association,USA 出版地:美国译名简介《美国政治科学评论》附《政治科学与政治学》美国政治科学学会会刊。

刊载政治理论、政治学、比较政治学、国际政治学等方面的文章、札记和书评。

附刊《政治科学与政治学》，报道该学会的研究动态和会议消息，并刊载学位论文。

SSCI来源刊，影响因子2.4482、报刊名称Comparative Politics. 创刊年:1968ISSN:0010-4159出版期次4/yr. 开本:21.5x15.5 页数:90 目录价:69/USD出版机构City University of New York, Political Science Program,USA 出版地:美国译名简介《比较政治学》刊载美国和其它国家的政治、社会、经济与宗教的研究和比较研究方面的文章与评论。

SSCI来源刊，影响因子1.0833、报刊名称Capitalism, Nature, Socialism. 创刊年:1989ISSN:1045-5752出版期次4/yr. 开本:21.5x15.5 页数:144 目录价:99/USD出版机构Guilford Publications Inc.,USA 出版地:美国译名简介《资本主义、自然、社会主义》由加利福尼亚大学社会学与经济学教授James O’Connor担任主编的探讨和论述社会主义生态学的国际性刊物。

内容涉及政治学、经济学、社会学和环境科学等。

PROQUEST有全文4、报刊名称Public Administration. 创刊年:1922ISSN:0033-3298出版期次4/yr. 开本:21.5x15.5 页数:124 目录价:324/GBP出版机构Blackwell Publishers Ltd.,UK 出版地:英国译名简介《公共行政》刊载公共行政管理和政策制定以及国际行政管理和比较研究等方面的文章。

《历史研究》关于文献引证标注方式的规定

《历史研究》关于文献引证标注方式的规定为了便于学术交流和推进本刊编辑工作的规范化，在研究和借鉴其他学术期刊有关规定的基础上，我们对文献引证标注方式进行了修订，并将从2002年第1期开始执行。

现特此公布其主要内容，敬请作者参照执行。

一普通图书引证内容及顺序为：①责任者与责任方式；②书名；③卷册；④出版者与出版时间；⑤版本；⑥页码。

（一）责任者与责任方式1、责任者可能是个人，也可能是团体、组织、机构。

责任者无法确定时，用“佚名”表示。

2、责任方式有多种，如果是撰著，在姓名之后加冒号表示；如果是“编”、“主编”、“编著”、“整理”“校注”等其他责任形式，直接跟书名，不空格，不加冒号。

如：朱汉国：《梁漱溟乡村建设理论研究》，山西教育出版社，1996年。

顾潮编著《顾颉刚年谱》，中国社会科学出版社，1993年。

3、两个或三个责任方式相同的责任者，用顿号隔开；有三个以上时，只取第一责任者，其后加“等”字，如：徐寿凯、施培毅校点《吴汝纶尺牍》，黄山书社，1990年。

许毅等：《清代外债史论》，中国财政经济出版社，1996年。

4、责任方式不同的责任者，用逗号分开；译著的翻译者及古籍的点校者、整理者等可放在书名之后。

如：严修自订，高凌雯补《严修先生年谱》，齐鲁书社，1990年。

A . 施阿兰：《使华记（1893---1897）》，袁传璋、郑永慧译，商务印书馆，1989年。

欧阳兆熊、金安清：《水窗春呓》，谢兴尧点校，中华书局，1984年。

（二）书名1、书名的副标题应一并标注；如书名较长，再次引证时，可用简称，但须在首次标注时注明。

2、书名中原有的补充说明等文字，应放在书名号内，如：任继愈主编《中国哲学发展史（先秦）》，人民出版社，1983年。

徐鼎新、钱小明：《上海总商会史（1902－1929）》，上海社会科学院出版社，1991年。

（三）出版者和出版时间1、非公元纪年的出版时间应照录，但1949年以后不用民国纪年。

如：陈恭禄：《中国近代史》，商务印书馆，民国24年。

On (q 2

k; n ;q k n n k; n k q q k k; n q q ;q q q q q q q ;q
Keywords: arc, multiset, Griesmer bound, optimal code, hyperoval, polynomial method
1. Introduction A multiset in the projective geometry (P ; L) = PG(r; q) is a mapping K : P ! N from the points of the geometry into the non-negative integers. This mapping can P be extended to the subsets of P by K(Q) = P 2Q K(P ), Q P . The integer K(Q) is called the multiplicity of the set Q. Sets Q with K(Q) = i are called i-sets. In particular, points, lines, and hyperplanes of multiplicity i are called i-points, iplanes, and i-hyperplanes, respectively. For a multiset K in PG(r; q), let ai denote the number of i-hyperplanes. The sequence fai gi is then called the spectrum of K. Let P and L be the sets of points and lines of PG(2; q). The multiset K is called a (k; n)-arc if K(P ) = k, K(l) n for any line l 2 L, and there is a line with

期刊《振动与冲击》论文模板(汇编)

□□□□□□论文题目□□□□□□□□□（三号黑体）XXX 1，XXX 2，XXX 2（小四宋体）（1.上海交通大学XXXXX学院XXXX，上海200240；2. XXXXXXXXXXXXXXXXXXXXXXX，上海200125）（小五宋体）摘要：(五号黑体)对岸桥起重机的有限元建模、约束处理作了分析与探讨, 在此基础上就岸桥起重机系统进行了模态和动态响应分析,得到了起重机系统前十阶振动频率、振型和位移响应时间历程。

该结果对岸桥起重机设计中如何避免在工作频率范围上共振现象的产生及限制在动载时过大动变形的产生有实际意义。

（小五宋体）关键词：（小五黑体）振动与波；岸桥起重机；有限元分析；动力响应中图分类号：TH212；TH213.3文献标识码：A□□□英文文题□□□（Times New Roman小四加粗）XXX 1XXX 2XXX 2(Times New Roman小四斜体)(1.Shanghai JiaoTong University, Shanghai 200240；2.Shanghai Zhenhua,Shanghai 200215) ( Times New Roman五号)Abstract:(五号加粗)A finite element model and its boundary conditions of quayside gantry crane are established in this paper. The first ten natural frequencies, the corresponding mode shapes and time-history of displacement response are given based on the analysis of the modes and dynamic response of this gantry crane system. The calculation and analysis above may be helpful for preventing the gantry crane from working on resonant area and for keeping the oversize dynamic deformation under restraint, which can be applied to design quayside gantry crane systems.Key words:vibration and wave; gantry crane; finite element analysis近年来起重运输机械制造行业采用新理论、新技术和采用新结构、新材料与新工艺后，其产品设计、性能水平和科技含量明显提高。

北京科技大学研究生开题报告要求

1) 文后参考文献原则上要求用文献本身的文字著录。如原文献为中文，则用中文著录；原文献为英文，则用英文著录；为美观起见，标点符号也类似处理。
2) 文献著录及引用采用顺序编码制。
2. 文献著录细则
1) 文献责任者著录细则
a) 文献责任者划分：按文责的负担情况将责任者分为主要责任者和其他责任者。主要责任者是指对文献的知识内容或艺术内容负主要责任的个人或团体，著者、编者、学位论文撰写者、专利申请者或所有者、报告撰写者、标准提出者、析出文献的作者等。其他责任者是指在参考文献中，主要责任者之外的责任者。例如：对于译著，著者为主要责任者，译者为其他责任者；对于学位论文，学位论文撰写者为主要责任者，导师为其他责任者；对于标准文献，可将标准文献的提出者或归口单位视为主要责任者，而将标准的起草单位以及起草人视为其他责任者。
3) 期刊文献著录格式
主要责任者．题名：其他题名信息[文献类型标志]．年，卷（期）:文献页码．获取和访问路径． [6]杨宗英．电子图书馆的现实模型[J]．中国图书馆学报，1996 (2)：24-29． [7]Dowler L. The research university's dilemma; resource sharing and research in a trans institutional environment [J]. Journal Library Administration, 1995, 21 (1/2): 5-26. [8] Des Marais D J, Strauss H, Summons R E, et al. Carbon isotope evidence for the stepwise oxidation of the Proterozoic environment[J]. Nature, 1992, 359: 605-609.

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The Histochemical Journal33:295–304,2001.©2001Kluwer Academic Publishers.Printed in the Netherlands.Effects of retinoids on porcine thyrocytes under different culture conditionsEleonore Fr¨o hlich1,Peter Brossart2&Richard Wahl31Anatomisches Institut,¨Osterbergstrasse3,D-72074T¨u bingen,Germany2Medizinische Klinik,Abteilung II,3Medizinische Klinik,Abteilung IV,Otfried-M¨u llerstrasse10,D-72076T¨u bingen, GermanyReceived26October2000and in revised form25April2001SummaryThe purpose of the paper was to study the morphological effects of retinoids on non-transformed cells such as thyrocytes.The formation of follicles was studied in primary cultures of porcine thyrocytes by adding retinol and thyroid stimulating hormone (TSH)to cells grown in the absence of TSH to form monolayers.The proliferation and apoptosis of thyrocytes were studied in cells both grown adherent to plastic surfaces and in suspension.Standard medium with traces of retinol and the same medium without retinol were used.Retinol alone was added to thyrocytes grown in the absence of TSH(TSH culture)or both retinol and TSH were added to cultures after stimulation with TSH(TSH⊕culture).The concentration was varied from0to80µM for retinol and from0to13µM for retinoic acid.At a concentration of13µM,the effect of retinol was similar to that of retinoic acid.At concentrations higher than40µM,retinol reduced the formation of thyroglobulin-immunoreactive follicles,whereas up to13µM retinoic acid had no obvious inﬂuence on follicle formation.The retinoids induced apoptosis under all experimental conditions.In contrast,a signiﬁcant decrease in proliferation and in the formation of thyroglobulin-immunoreactive follicles was observed only in adherent cells cultured in customary medium.The decrease in functional follicles after treatment with retinol suggests a de-differentiating effect of retinoids on normal thyrocytes and is in contrast with the differentiating effect of retinoids observed in cancer cells.IntroductionRetinoids have been shown to alter the proliferation rate, induce apoptosis and inﬂuence cell-speciﬁc functions in trans-formed cells such as cancer cells and cell lines(Stewart& Thomas1997,Ahn et al.1995,Toma et al.1998)but also in non-transformed cells.In normal thyrocytes theseﬁndings are,in part,controversial and not well studied.The contro-versial results are caused in part by the fact that effects of retinoids on human thyrocytes not only depend on culture conditions,e.g.,cell density or speciﬁc radioactivities used, but also on the medical treatment and the histological fea-ture of the original tissue.In this respect primary cultures of porcine thyrocytes from nine-months-old pigs show less vari-ations.Porcine thyrocytes grow as a monolayer when cultured in the absence of TSH or form follicle-like structures when cultured in the presence of TSH.In contrast to cell lines,they not only take up but also organify iodide(Fayet et al.1982). The inhibition of proliferation in cancer cells is an impor-tant effect of retinoids.In non-transformed cells the effect of retinoids on proliferation is variable and dose-dependent: DNA synthesis can be decreased(Hashimoto et al.1985, Kruse&Tseng1993,Zouboulis et al.1993,)or increased (Enomoto et al.1990,Niles et al.1990,Takishita et al.1990, Mark et al.1992,Friedman et al.1993,Varani et al.1996) depending on the type of cell investigated.In primary human thyrocytes,an inhibition of prolifer-ation under the inﬂuence of retinol has been reported by del Senno et al.(1993)but was not found in cultures of porcine thyrocytes(Arai et al.1991).These differences may represent species-speciﬁc differences.It is also possible that thyrocytes from other human samples do not show this effect because incorporation of3H-thymidine into human thyrocytes differs markedly between studies(Errick et al.1986,Williams et al. 1987,Namba et al.1993)and the response to certain regu-lators of proliferation may vary in cell cultures with differ-ent rates of proliferating nuclei.In contrast to human thyro-cytes,the rates of3H-thymidine incorporation into porcine thyrocytes differ only to a minimal extent between studies (Tsuchiya et al.1990,Wahl et al.1992).In addition to the effects of retinoids on proliferation the induction of apoptosis is another important effect of retinoids (Glozak&Rogers1996,Kim et al.1996,Toma et al.1997). In non-transformed cells,such as preadipocytes and thy-rocytes the apoptotic effect of retinoids has been shown (Chawla&Lazar1994,Fr¨o hlich&Wahl1999).Apoptosis is also induced by unphysiological growth conditions as loss of contact either between cells or between cells and the substra-tum of the culture plates(Peluso et al.1996Strater et al.1996, Hague et al.1997).In thyrocytes a potential additive effect of retinoid and unphysiological growth can be studied by a variation of both the extent of the contact to the substratum296 E.Fr¨o hlich et al.(suspension vs.adherent culture)and the state of aggregation of the cells(TSH⊕vs.TSH culture).In many non-transformed cells,nanomolar concentrations of retinoic acid improve cell-speciﬁc function(Dillehay et al. 1988,Guibourdenche et al.1997).Retinoic acid is used most often because its effect in numerous cells is stronger than that of equimolar concentrations of retinol(Kochhar et al.1988, Lee et al.1991,Adams1993,Chertow et al.1996,Tembe et al.1996,Tajima et al.1997).Thyrocytes behave differ-ently in this respect:ﬁrstly,retinoids decrease cell-speciﬁc functions like the TSH-induced uptake of iodide and the release of organiﬁed iodine(Arai et al.1991,Namba et al. 1993)and second,the effect of retinoic acid appears to be similar to that of retinol(Arai et al.1991).The action of retinoids on thyrocytes is especially interest-ing because hypovitaminosis A may increase but may also reduce the levels of thyroid hormones in vivo(Haubold& Lackner1951,Horvat&Maver1958)and because retinoic acid has been reported to re-differentiate differentiated thyroid carcinomas(Simon et al.1996).To evaluate the inﬂuence of basic levels of retinol prior to the retinoid stimulus both customary medium and retinol-free medium was tested.Toﬁnd out whether the effect of retinoids was inﬂuenced by the aggregation state of the thyrocytes or by the contact to the substratum,follicle and monolayer cultures as well as adherent and suspension cultures were tested.To estimate the potency of different retinoids in thyrocytes the effects of all-trans retinol were compared to those of lower to similar molar concentrations of13-cis retinoic acid. Materials and methodsCulture conditionsTo study the inﬂuence of the contact to the substratum and the inﬂuence of the state of aggregation on the effect of retinol,thyrocytes were studied under different culture conditions:they were grown(a)either on polystyrene sur-faces(adherent culture)or in plates coated with polyHEMA (poly(hydroxyethyl)methylacrylate)to prevent attachment (suspension culture),and(b)either in the absence of TSH to form monolayers or in the presence of TSH to form folli-cles.Thyrocytes were cultured for three days in the presence or absence of TSH,respectively.Successively,fresh medium with retinol+TSH or13-cis retinoic acid+TSH was added to follicle(TSH⊕)cultures and fresh medium with retinol or13-cis retinoic acid alone was added to monolayer(TSH )cultures.Only for the investigation of the aggregation of thyrocytes to follicles,retinol+TSH were added to TSH cultures.In general,cultures were evaluated after48h of stimulation with all-trans retinol or13-cis retinoic acid.Isolation of thyroid cellsPorcine thyroid glands were obtained from the local slaugh-terhouse and cells were isolated as previously described (Wahl et al.1992).For immunocytochemistry and electron microscopy3×106cells per well(6-well culture plate, Costar No3506)were seeded.For all other investigations 5×105cells were seeded per well(24-well culture plate, Costar No3524)in0.75ml NCTC-135medium(custom-ary and special retinol-free preparation,Gibco BRL)sup-plemented with2%Ultroser G(IBF,no retinol detectable by HPLC)and1mU/ml porcine thyrotropin(TSH,Sigma) and with the addition of penicillin(200IU/ml),streptomycin (0.2mg/ml).To prevent contamination with mycoplasma ciproﬂoxacin(0.06mg/ml,Bayer)was also added to the cul-tures.This contamination occurs frequently but should be prevented because mycoplasmas also incorporate thymidine. It is not likely that ciproﬂoxacin damages the thyrocytes because ultrastructure,125iodine or3H-thymidine uptake were similar in the ciproﬂoxacin-treated and untreated cultures. Addition of retinol or13-cis retinoic acid and the subsequent experiments were carried out under low illumination to pre-vent degradation of the retinoids.All-trans retinol(Sigma)or 13-cis-retinoic acid(Sigma,diluted in methanol)was added to both cultures adherent to plastic surfaces and to cultures in suspension.The concentration varied from0to60nmol/well (0–80µM)for retinol,and from0to10nmol/well(0–13µM) for13-cis-retinoic acid.Methanol without the respective retinoid served as the control.Cells were cultured at37◦C at 100%humidity in5%CO2and95%air.All preparations were tested for presence of mycoplasma(Mycoplasma detection kit,Roche).In the adherent cultures,cells were seeded on tissue cul-ture treated polystyrene surfaces(Costar No3506or3524). In suspension the culture plates from Costar were coated with polyHEMA(poly(hydroxyethyl)methylacrylate,Sigma, diluted1:10in ethanol)to prevent attachment.Determination of3H-thymidine uptakeCultures(5×105cells/750µl)with or without retinoid were incubated with37kBq[6-3H]-thymidine/ml(speciﬁc activ-ity:935GBq/mmol,Amersham)for24h.The cells were harvested with a Cell Harvester(Skatron Instruments)on ﬁltermats(printedﬁltermat A1205-401,Wallac).Driedﬁl-termats were put in sample bags(Sample Bags1204-411, Wallac),scintillant(Ultima Gold TM Scintillant,Packard)was added and the bags were welded together.Samples were mea-sured in a Betaplate1205(Wallac).Determination of total DNADNA was isolated with the Puregene TM kit(Biozym)suitable for the determination of DNA of various sources.Then cells were scraped off the culture dishes,centrifuged(13,000g, 5min)and resuspended in10µl of residualﬂuid.Cell Lysis Solution of150µl and0.75µl RNAse A solution were added. After incubation for30min at37◦C and cooling to room tem-perature(RT),50µl of Protein Precipitation Solution was added.The suspension was mixed for20sec and centrifuged at13,000g for3min.The supernatant was transferred toRetinoid action in different cultures of thyrocytes297another vial and150µl isopropanol was added.The pre-cipitate was centrifuged and washed once with150µl70% ethanol.The pellet was then air-dried for15min.After the addition of25µl of DNA Hydration Solution the mixture was incubated for1h at65◦C.Absorbances at260nm and280nm were determined using a GeneQuant II RNA/DNA calculator (Pharmacia Biotech).ImmunocytochemistryFollicles expressing thyroglobulin(TG)were detected by immunocytochemistry with a commercial monoclonal anti-thyroglobulin antibody(Sigma).Cells wereﬁxed with 4%paraformaldehyde in0.1M phosphate buffer pH7.4 (30min,25◦C or12h,4◦C),washed with phosphate buffer, dehydrated,scraped from the bottom of the culture well, centrifuged(500g,4min)in microtubes,and embedded in parafﬁn.For testing of the antibody,intact porcine thyroid glands wereﬁxed for12h in the sameﬁxative as the cells, dehydrated and embedded in parafﬁn.Sections(8µm)were cut and mounted on slides coated with chrome-gelatine.The wax was then removed from the sections.Sections were then rehydrated and incubated with blocking serum(5%rab-bit serum,1%BSA,0.5%Triton X100)for30min at RT. Subsequently,they were incubated with anti-thyroglobulin from mouse(Sigma,1:50in0.1M PBS,5%rabbit serum, 0.5%Triton X100)for1h at RT followed by an incubation with anti-mouse antibody from goat(Sigma1:50,in0.1M PBS,5%rabbit serum,0.5%Triton X100)for1h at RT and with peroxidase-anti-peroxidase-complex(from mouse, 1:400,Dianova)for1h at RT and developed with0.05% diaminobenzidine(Sigma)+0.03%H2O2in phosphate buffer.The identiﬁcation of TG-immunoreactive follicles was easier when those thyrocytes that also contained TG in their cytoplasm were not stained because of better contrast.There-fore,for visualization of the TG-antibody complex an incu-bation time of3min with the peroxidase substrate was chosen after which only the content of follicles but not all thyrocytes were stained.The number of thyroglobulin-immunoreactive follicles per1000thyrocytes in the section was determined. TdT-mediated dUTP nick end labelling(TUNEL)Unless stated otherwise,cells wereﬁxed48h after addi-tion of the respective retinoid to the precultured cells and embedded in parafﬁn as described above.Parafﬁn sections were dewaxed,rehydrated and treated with proteinase K (20µg/ml)in10mM Tris/HCl pH7.4for15min at RT.The sections were then rinsed in Tris/HCl buffer and incubated with TUNEL mixture(terminal deoxynucleotidyltransferase (TdT200U/ml)and FITC-labelled dUTP(10µmol/ml)in TdT buffer(25mM Tris–HCl,200mM sodium cacodylate, 5mM cobalt chloride,Roche)for60min at37◦C.Subse-quently,the sections were rinsed in Tris/HCl buffer and incu-bated with converter solution(alkaline phosphatase labelled anti-FITC antibody,Roche)for30min at37◦C.Alkaline phosphatase labelled antibody was detected after an incu-bation for20min with a solution containing8mg naphthole AS-MX phosphate(Sigma)dissolved in0.2ml dimethylfor-mamide,1mM levamisole and10mg fast red TR salt(Sigma) per10ml0.1M Tris/HCl-buffer pH8.2.Detection of apoptotic cells with annexin VThe cells were harvested48h after addition of the respective retinoid.To obtain single cells,cells were passed through a0.025mm mesh sieve(Cat.No.1.4301,Weisse&Eschrich) and centrifuged at400g for6min.The cells were then washed with0.1M PBS pH7.4,and apoptotic cells were detected with the Apoptosis Detection Kit(R&D Systems):100µl of 106cells/ml suspended in binding buffer were incubated with 10µl annexin V-FITC(10µg/ml)and10µl propidium iodide (50µg/ml)for15min at RT in the dark.The FITC signal was detected at488nm,that of propidium iodide at670nm. Electron microscopyThe cells wereﬁxed for2h with2.5%glutaraldehyde in 0.05M cacodylate-buffer pH7.4containing2%sucrose, stained with OsO4and uranyl acetate(en bloc),dehydrated and embedded in Epon.The sections were examined with a Phillips EM300electron microscope.Laser scan microscopyFor the determination of the follicle size,thyrocytes were cul-tured on cover slips.Cells wereﬁxed with4%paraformalde-hyde for30min and incubated with SYTO61Lifestain (Molecular Probes,1:5000in PBS)for10min at RT.After rinsing in PBS,the coverslips were mounted in Kaiser’s glyc-erol and viewed(with an excitation wavelength of628nm and emission at645using an appropriateﬁlter set)with a Laser Scan microscope410(Zeiss).For each concentration of the retinoid the diameter of10follicles was recorded. Evaluation and statisticsIn most experiments(thyroglobulin-immunoreactivity, TUNEL,annexin V-binding)different samples of one dish were evaluated.If different dishes of a given preparation were investigated,results differed by5–10%from each other.The fraction of apoptotic cells depended on the quality of the iso-lated cells.Preparations with more than20%of apoptotic cells in untreated cultures were excluded because such a high fraction of apoptosis suggests an unusual damage of cells. These preparations differed also in another aspect from the other preparations in that the yield of cells was very low and almost all cells were apoptotic already at low concentrations of retinol.The diagrams of experiments repeated three times show mean±standard deviation.Statistical analysis of the cor-relations was done using regression analysis(SPSS®)or Wilcoxon signed rank test.298E.Fr ¨o hlich et al.Table 1.Overview of the culture conditions tested.ParameterCustomary NCTC medium Retinol-free NCTC medium Adherent culture Suspension culture Adherent culture Suspension culture TSH ⊕TSH TSH ⊕TSH TSH ⊕TSH TSH ⊕TSH TG-ir n.a.S n.d.n.d.n.a.NS n.d.n.d.3H-uptake S S NS NS NS NS NS NS DNA S S n.d.n.d.NS NS n.d.n.d.TUNEL S S S S S S S S Annexinn.d.n.d.SSn.d.n.d.SSS:signiﬁcant;NS:not signiﬁcant;n.a.:not applicable;n.d.:notdetermined.Figure 1.Confocal image of a follicle grown in an adherent culture after stimulation with 13µM retinol.Nuclei stain red,the follicle lumen is notstained.Bar:20µm.ResultsThe effect of retinol and retinoic acid was tested under a variety of culture conditions.In many cases the different culture conditions showed similar effects.Table 1presents an overview of the culture conditions tested.Therefore,in the following paragraphs only special results will be mentioned.Inﬂuence of retinol on the formation of thyroglobulin-immunoreactive folliclesTo study the aggregation of thyrocytes to follicles under the inﬂuence of the respective retinoid,retinoid and TSH were added to cells,which had been pre-cultured in the absence of TSH to form monolayers.Only adherent cultures were inves-tigated.Addition of retinoid and TSH to cells that had been pre-cultured in the presence of TSH to form follicles served as controls.Follicles formed in the presence of more than 13µM retinol appeared to be smaller than those formed in controls to which no retinol has been added.Thyrocytes cul-tured in a medium with high ﬁnal concentrations of retinol (>50µM)rarely formed follicles.We tried to record the dis-tribution pattern of the follicle sizes by confocal scanning of the follicles.Aggregations of thyrocytes were discerned from follicles by the presence of a lumen in cultures stained with a ﬂuorescent nuclear stain (Figure 1).Due to method-ological problems only follicles of a limited size-range could be evaluated:small follicles ( approx.25µm)could not be identiﬁed beyond doubt because the lumen was hardly detectable.Follicles greater than 120µm could not be identi-ﬁed because these follicles collapsed during the investigation time and no clear lumen was discernible.Therefore,only a crude classiﬁcation of the follicle sizes was made.In cul-tures with 27–53µM retinol only 32±10%of the follicles were larger than 50µm.In cultures with 0–13µM retinol (or retinoic acid)71±7%were larger than 50µm.To examine whether follicles formed in the pres-ence of retinol secreted and/or stored thyroglobulin,weRetinoid action in different cultures of thyrocytes299Figure2.Anti-thyroglobulin immunoreactivity(dark staining)in an adherent culture after stimulation with retinol.For the formation of folli-cles,cells were cultured for three days in the presence of1mU/ml TSH. Thereafter,fresh medium with retinol and TSH was added.Forty-eight hours after retinoid stimulation the cultures were evaluated.(a)At13µM retinol preparations contain thyroglobulin-positive(black arrows),and thyroglobulin-negative(white arrows)follicles.(b)At50µM retinol fol-licles are thyroglobulin-negative(white arrows).Bar:50µm. determined the fraction of follicles with and without thyroglobulin-immunoreactivity.At low concentrations (≤13µM)of the retinoids many of the discernible folli-cles are thyroglobulin-immunoreactive(Figure2a)whereas at high concentrations(≥50µM)only few,predominantly thyroglobulin-negative follicles are seen(Figure2b).In gen-eral,the total number of follicles at a given concentration of retinol was higher when both retinol and TSH were added to cultures with pre-formed follicles than when retinol and TSH were added to pre-formed monolayer cultures.On the other hand the retinol-dependent decrease in the number of thyroglobulin-immunoreactive follicles was similar if retinol was added to pre-existent follicles or to monolayers:the num-ber of follicles decreased signiﬁcantly after addition of retinol (Figure3).Figure3.Thyroglobulin-immunoreactive follicles in adherent cultures under stimulation with retinol(n=3).Thyrocytes were cultured three days in the presence of1mU/ml TSH to form follicles.Subsequently, fresh medium with TSH and retinol was added for48h and the num-ber of immunoreactive follicles per1000thyrocytes in the section was recorded.Retinol added to the medium causes a decrease in the number of immunoreactive follicles(r=0.73,p=0.0001).If retinol-free medium was used the decrease was signif-icant from7to80µM retinol not from0to80µM retinol because the formation of thyroglobulin-immunoreactive follicles in the retinol-free medium was very low(25±13 follicles vs.50±15follicles in the customary medium with 0.8µM retinol).When only retinol and no TSH was added to the cultures only between0and5follicles/1000thyrocytes were recorded.At concentrations from0.1to13µM13-cis retinoic acid no signiﬁcant decrease in the number of thyroglobulin-immunoreactive follicles was observed.The number of thyroglobulin-immunoreactive follicles varied between 51±11at0.1µM and38±12at13µM retinoic acid.Inﬂuence of retinol on the rate of3H-thymidine uptake under different culture conditionsUptake of3H-thymidine was measured in customary NCTC or in retinol-free NCTC medium after pre-incubation with-out TSH(TSH culture)and after pre-incubation with TSH(TSH⊕culture).In general,the thymidine uptake in TSH⊕cultures was10–15%higher than in TSH cul-tures.Only in the adherent cultures pre-cultured in custom-ary NCTC medium a signiﬁcant correlation of thymidine uptake and concentration of retinol was recorded:retinol (≥13µM)reduced the rate of thymidine uptake in thyro-cytes(Figure4a).When thyrocytes were pre-cultured in the retinol-free medium no signiﬁcant dose-dependent decrease or increase in the uptake of3H-thymidine was detected. Thymidine uptake into thyrocytes in retinol-free NCTC medium was markedly lower than in the customary medium with0.8µM retinol(495±96cpm vs.946±111cpm).In cultures treated with13-cis retinoic acid3H-thymidine uptake was similar(1360±280cpm at13µM)to retinol-treated (1500±307cpm at13µM)cultures(Figure5).300 E.Fr ¨o hlich etal.Figure 4.Uptake of 3H-thymidine and amount of DNA of thyrocytes grown as adherent monolayers in customary medium for 48h (n =5).Retinoladded to the medium causes a decrease in 3H-thymidine incorporation and in the amount of DNA.(a)The correlation between uptake of 3H-thymidine and concentration of retinol was r =0.88,p =0.0002.(b)The correlation between amount of DNA and concentration of retinol was r =0.66,p =0.005.Figure parison of 3H-thymidine uptake after stimulation with either retinol or 13-cis retinoic acid into thyrocytes grown as adherent monolayers in retinol-depleted medium for 24h (n =3).No signiﬁcant difference in the rate of 3H-thymidine uptake was noted.Quantiﬁcation of DNA in thyrocytesOnly in adherent cultures in customary medium and not in suspension cultures were signiﬁcant changes of the amount of DNA recorded:in adherent cultures approximately equal amounts of DNA (6.2±1.4µg/well and 5.8±1.7µg/well)prior to the treatment with retinol were obtained in TSH and in TSH ⊕cultures.Corresponding to the decrease in the thymidine uptake,the amount of total DNA also decreased after incuba-tion with 13–80µM retinol.Regression analysis revealed a signiﬁcant negative correlation between retinol and total DNA (Figure 4b).In cultures treated with 0.1–13µM 13-cis retinoic acid total DNA was 10–15%lower than after treatment with 13µM retinol.TUNEL-labelling of retinol-treated cells under different culture conditionsApoptotic cells were identiﬁed by the TUNEL-test that rec-ognizes DNA with double strand breaks.In sections of porcine thyroid glands TUNEL-positive follicle cells were detected only sporadically (data not shown).ThyrocytesFigure belling of apoptotic cells by the TUNEL reaction in adher-ent follicle culture (alkaline phosphatase detection):(a)After 48h in the presence of 13µM retinol follicles (arrow)and TSH few TUNEL-positive cells are seen.(b)In cultures with high concentrations of retinol (80µM,48h)no follicles are found and apoptotic cells (stained dark)are numerous.Bar:50µm.Retinoid action in different cultures of thyrocytes301integrated into follicles generally showed negative TUNEL-reaction,but at higher concentrations of retinol more cells became TUNEL-positive(Figure6a,b).Under all culture conditions the rate of TUNEL-positive cells increased sig-niﬁcantly at concentrations higher than27µM of retinol. Adherent/suspension and TSH /TSH⊕cultures are listed separately because the loss of the adhesion to the substratum or un-physiological growth(TSH culture)was expected to produce a higher fraction of TUNEL-positive cells.In adherent cultures the fraction of apoptotic cells in TSH and TSH⊕cultures was lowest one day after treatment with retinol and this fraction increased with the duration of the incubation.Figure7shows the fraction of apoptotic(TUNEL-positive) thyrocytes after treatment with increasing doses of retinol for 48h.A signiﬁcant positive correlation was found between the fraction of apoptotic cells and the concentration of retinol (Figure7:upper panel).To study whether the effect of retinol on apoptosis was reversible,we excluded retinol from the culture medium after one or two days of incubation with 13–60µM retinol and continued incubating the cultures for one or two more days without retinol.The fraction of apop-totic cells increased from about10%at13µM retinol to about 50%at60µM retinol under all conditions indicating that the action of retinol was irreversible.The fraction of apoptotic cells after incubation with 0.1–13µM13-cis retinoic acid varied between7±4and 17±10%;it was slightly but not signiﬁcantly lower than that after incubation with retinol.In suspension cultures retinol had similar effects on the fraction of TUNEL-positive cells:A signiﬁcant positive cor-relation between the concentration of retinol and the fraction of apoptotic cells was also noted in TSH and TSH⊕sus-pension cultures(Figure7:lower panel).The slope of the regression line calculated for the TSH suspension cultures differed signiﬁcantly(p<0.05)from the slope of the regres-sion lines calculated for the TSH⊕suspension cultures and for the TSH and TSH⊕adherent cultures.Annexin V binding assayDue to the damage of the cells by detachment from the sub-stratum only suspension cultures could be evaluated with this assay.The binding of annexin V which identiﬁes early apop-totic cells was detected byﬂuorescence-activated cell sorting (FACS).For the identiﬁcation of necrotic cells,propidium iodide was added.With increasing concentrations of retinol more cells were apoptotic as evidenced by annexin V-FITC binding(Figure8).For any concentrations of retinol up to 80µM the fraction of annexin V-positive cells was about20% higher in TSH than in TSH⊕cultures.At a given concen-tration of retinol more cells were positive with the annexin V-labelling than with the TUNEL-labelling assay.The fraction of annexin V-positive cells in cultures treated with13µM retinol was15%higher than in cultures treated with13µM13-cis retinoicacid.Figure7.Fraction of TUNEL-positive thyrocytes under treatment with retinol for48h in adherent monolayer(TSH ;r=0.85,p<0.00005) and follicle(TSH⊕;r=0.73,p<0.00005)culture and in TSH (r=0.82,p<0.00005)and TSH⊕(r=0.92,p<0.00005)suspen-sion cultures(n=3).According to the slopes of the regression lines, the effect of retinol in TSH suspension culture differs signiﬁcantly (p<0.05)from that of all other cultureconditions.Figure8.Retinol dose-dependent changes in the distribution of annexin V-positive thyrocytes(suspension monolayer culture). Ultrastructure of thyrocytes after retinol treatmentTo show that retinol and13-cis retinoic acid induced predom-inantly apoptotic cell death the ultrastructure of the retinoid-treated cells was investigated.Dilatation of the endoplasmic reticulum,peripheral condensation of chromatin and frag-mentation of the nucleus could be detected in cultures treated with27µM retinol or higher(Figure9).At concentrations of。