IRM_Chapter_6e_18
J.Nanopart.Res.,2009,11,1513–Rheological behaviour of ethylene glycol-titanate nanotube nano
BRIEF COMMUNICATIONRheological behaviour of ethylene glycol-titanate nanotube nanofluidsHaisheng Chen ÆYulong Ding ÆAlexei Lapkin ÆXiaolei FanReceived:11July 2008/Accepted:4February 2009/Published online:26February 2009ÓSpringer Science+Business Media B.V.2009Abstract Experimental work has been performed on the rheological behaviour of ethylene glycol based nanofluids containing titanate nanotubes over 20–60°C and a particle mass concentration of 0–8%.It is found that the nanofluids show shear-thinning behaviour particularly at particle concentrations in excess of *2%.Temperature imposes a very strong effect on the rheological behaviour of the nanofluids with higher temperatures giving stronger shear thinning.For a given particle concentration,there exists a certain shear rate below which the viscosity increases with increasing temperature,whereas the reverse occurs above such a shear rate.The normalised high-shear viscosity with respect to the base liquid viscosity,however,is independent of temperature.Further analyses suggest that the temperature effects are due to the shear-dependence of the relative contributions to the viscosity of the Brownian diffusion and convection.The analyses also suggest that a combination of particle aggregation and particle shape effects is the mechanism for the observed high-shear rheological behaviour,which is also supported by the thermal conductivity measure-ments and analyses.Keywords Rheological behaviour ÁEthylene glycol ÁTitanate nanotube ÁNanofluid ÁThermal conductivityNanofluids are dilute suspensions of particles with at least one dimension smaller than about 100nm (Choi 1995).Such a type of materials can be regarded as functionalized colloids with special requirements of a low-particle loading,a high-thermal performance,favourable flow/rheolgocial behaviour,and a great physical and chemical stability over a wide range of process and solution chemistry conditions.Nano-fluids have been shown to be able to enhance heat transfer (Choi 1995;Wang and Mujumdar.2007),mass transfer (Krishnamurthy et al.2006),and wetting and spreading (Wasan and Nikolov 2003),and have been a hot topic of research over the past decade (Wang and Mujumdar 2007;Keblinski et al.2005).Most published studies have focused on the heat transfer behaviour including thermal conduction (Choi 1995;Wang et al.1999;Wang and Mujumdar 2007;Keblinski et al.2005;Eastman et al.2001;He et al.2007;Ding et al.2006),phase change (boiling)heat transfer (Das et al.2003;Pak and Cho 1998),and convective heat transfer (Wang and Mujumdar 2007;Keblinski et al.2005;He et al.2007;Ding et al.2006,Chen et al.2008;Prasher et al.2006a and Yang et al.2005).Only few studies have been devoted to the rheological behaviour ofH.Chen ÁY.Ding (&)Institute of Particle Science and Engineering,University of Leeds,Leeds,UK e-mail:y.ding@pkin ÁX.FanDepartment of Chemical Engineering,University of Bath,Bath,UKJ Nanopart Res (2009)11:1513–1520DOI 10.1007/s11051-009-9599-9nanofluids(He et al.2007;Chen et al.2008;Prasher et al.2006a,b;Kwak and Kim2005;Lee et al.2006), although there is a large body of literature on suspensions rheology;see for example,Russel et al. (1991);Chow(1993);Petrie(1999),Larson(1999); Goodwin et al.(2000)l;Mohraz et al.(2004);Larson (2005);Egres and Wagner(2005);Abdulagatov and Azizov(2006).Particularly,there is little in the literature on the effect of temperature on the rheo-logical behaviour of nanofluids.Clearly,there is a gap in the current rheological literature for this type offluids.Furthermore,recent work has shown that the thermal behaviour of nanofluids correlates well with their rheological behaviour(Prasher et al.2006a, b;Chen et al.2007a;Abdulagatov and Azizov2006). In a recent study,we investigated systemically the rheological behaviour of ethylene glycol(EG)based spherical TiO2nanofluids(Chen et al.2007b).The results show that the nanofluids are Newtonian over a shear rate range of0.5–104s-1and the shear viscosity is a strong function of temperature,particle concentration and aggregation microstructure.This work is concerned about the rheological behaviour of EG based nanofluids containing titanate nanotubes (TNT).The specific objectives of the work are to investigate the effects of particle shape,particle concentration and temperature on nanofluids viscosity, and to understand the relationship between the rheo-logical behaviour and the effective thermal conductivity of nanofluids.It is for thefirst time that the rheological behaviour of a highly viscous EG based TNT nanofluids is investigated in a systematic manner.As will be seen later,the results of this work provide further evidence that the rheological measure-ments could provide information of particle structuring for predicting the effective thermal conductivity of nanofluids.The EG-TNT nanofluids used in this work were formulated by using the so-called two-step method with EG purchased from Alfa Aesar and TNT synthesized in our labs using a method described elsewhere(Bavykin et al.2004).The details of nanofluids formulation can be found elsewhere(Wen and Ding2005;He et al.2007;Chen et al.2007b). The TNT particles have a diameter(b)of*10nm and a length(L)of*100nm,giving an aspect ratio of(r=L/b)of*10.To avoid complications in interpreting the experimental results,no dispersants/ surfactants were used in the formulation.The nanofluids formulated were found stable for over 2months.The rheological behaviour of the nano-fluids was measured by using a Bolin CVO rheometer (Malvern Instruments,UK)over a shear rate range of 0.03–3,000s-1,a nanoparticle mass concentration of w=0–8%,and a temperature range of20–60°C (293–333K).The nanofluids were characterised for their size by using a Malvern Nanosizer(Malvern Instruments,UK)and a scanning electron microscope (SEM).The average effective particle diameter was found to be*260nm for all nanofluids formulated. This size is much larger than the equivalent diameter of the primary nanoparticles due to aggregation;see later for more discussion.Note that the particle size characterisation was performed both before and after the rheological measurements and no detectable changes to particle size were found.Figure1shows the viscosity of pure EG and EG-TNT nanofluids as a function of shear rate at 40°C.The results at other temperatures are similar.It can be seen that the EG-TNT nanofluids exhibit highly shear-thinning behaviour particularly when the TNT concentration exceeds*2%.Such behaviour is different from the observed Newtonian behaviour of EG-TiO2nanofluids containing spherical nanoparti-cles over similar shear rate range(Chen et al.2007b) where the base liquid,EG,is the same as that used in the current wok.The behaviour is similar to the observations of carbon nanotube nanofluids(Ding et al.2006)and CuO nanorod nanofluids(Kwak and Kim2005),although there are important differencesbetween them such as temperature dependence as will be discussed later.The shear-thinning behaviour of well-dispersed suspensions can be interpreted by the structuring of interacting particles(Doi and Edwards1978a,b and Larson1999).In a quiescent state,a rod-like particle has three types of motion due to Brownian diffusion: rotational(end-over-end)motion around the mid-point and translational motion in parallel or perpendicular to the long axis.For dilute suspensions with a number density,c,ranging between0and1/L3or volume fraction,u,ranging between0and1/r2),the average spacing between the particles is larger than the longest dimension of the rod,and zero shear viscosity can be approximated by gð0Þ%g0ð1þAÁcL3Þwith g0the base liquid viscosity and A,a numerical constant(Doi and Edwards1978a).For suspensions with 1/L3\c\1/bL2or1/r2\f/\1/r,the rod-like particles start to interact.The rotational motion is severely restricted,as well as the translational motion perpendicular to the long axis,and the zero shear viscosity can be estimated by gð0Þ%g0ð1þðBcL3Þ3Þ; with B a numerical constant(Doi and Edwards1978b). As a consequence,the zero shear viscosity can be much greater than the base liquid viscosity.The large viscosity is due to the rod-like shape effect and the viscosity is very sensitive to shear,which tends to align particles and hence the shear-thinning behaviour as shown in Fig.1.Note that the above mechanism can give a qualitative explanation for the experimental observations at low-shear rates and the shear-thinning behaviour as shown in Fig.1,it does not explain the high-shear viscosity of the nanofluids,which will be discussed later.It should also be noted that the criteria for classifying nanofluids given above need to be modified due to the presence of aggregates;see later for more discussion.Figure2shows the shear viscosity of4.0%EG-TNT nanofluids as a function of shear rate at different temperatures.The results under other concentrations are similar.It can be seen that the temperature has a very strong effect on the rheological behaviour of nanofluids with higher temperatures giving stronger shear thinning.For shear rates below*10s-1,the shear viscosity increases with increasing temperature, whereas the trend is reversed when the shear rate is above*10s-1.As mentioned above,this behaviour was not observed for carbon nanotube(Ding et al. 2006)and CuO nanorod(Kwak and Kim2005)nanofluids and we have not seen reports on such behaviour for nanofluids in the literature;see later for more discussion on the underlying mechanisms. Figure2also shows that the strongest shear thinning occurs at40–60°C,whereas very weak-shear thinning takes places at20–30°C.It is also noted that the shear viscosity of nanofluids at all temperatures investigated approaches a constant at high-shear rates.If the high-shear viscosity is plotted against temperature,Fig.3is obtained where the shear rate corresponding to the high-shear viscosity is taken as *2,000s-1.An inspection of all the data indicates that theyfit the following equation very well:ln g¼AþBÂ1000=TþCðÞð1Þwhere g is the shear viscosity(mPaÁs),T is the absolute temperature(K),and A,B and C areconstants given in Table1.Equation(1)takes a similar format as that widely used for liquid viscosity (Bird et al.2002)and for EG based nanofluids containing spherical particles(Chen et al.2007b).If the measured high-shear viscosity is normalized with respect to the shear viscosity of the base liquid, the relative increaseðg i¼ðgÀg0Þ=g0Þof the high-shear viscosity is found to be only a function of concentration but independent of temperature over the temperature range investigated in this work.The relative increments in the shear viscosities of nano-fluids containing0.5%,1.0%,2.0%,4.0%and8.0% particles are 3.30%,7.00%,16.22%,26.34%and 70.96%,respectively.Similar temperature indepen-dence of the shear viscosity was also observed for EG-TiO2and water-TiO2nanofluids containing spherical nanoparticles(Chen et al.2007b).The experimentally observed temperature depen-dence can be interpreted as follows.Given the base liquid and nanoparticles,the functional dependence of viscosity on shear rate is determined by the relative importance of the Brownian diffusion and convection effects.At temperatures below*30°C,the contribu-tion from the Brownian diffusion is weak due to high-base liquid viscosity.As a consequence,the shear dependence of the suspension is weak(Fig.2).The contribution from the Brownian diffusion becomes increasingly important with increasing temperature particularly above40°C due to the exponential dependence of the base liquid viscosity on temperature (Fig.3).At very high-shear rates,the Brownian diffusion plays a negligible role in comparison with the convective contribution and hence independent of the high-shear viscosity on the temperature.We now start to examine if the classical theories for the high-shear viscosity predict the experimental measurements(note that there is a lack of adequate theories for predicting the low shear viscosity).Figure4shows the shear viscosity increment as a function of nanoparticle volume concentration together with the predictions by the following Brenner &Condiff Equation for dilute suspensions containing large aspect ratio rod-like particles(Brenner and Condiff1974):g¼g01þg½ uþO u2ÀÁÀÁð2Þwhere the intrinsic viscosity,½g ;for high-shear rates has the following form(Goodwin and Hughes2000):½g ¼0:312rln2rÀ1:5þ2À0:5ln2rÀ1:5À1:872rð3ÞAlso included in Fig.4are the data for EG-TiO2 nanofluids with spherical nanoparticles(Chen et al. 2007b)and predictions by the Einstein Equation (Einstein1906,1911)for dilute non-interacting suspensions of spherical particles,g¼g01þ2:5uðÞ: It can be seen that both the Einstein and Brenner& Condiff equations greatly underpredict the measured data for the EG-TNT nanofluids.The high-shear viscosity of EG-TNT nanofluids is much higher than that of the EG-TiO2nanofluids containing spherical nanoparticles,indicating a strong particle shape effect on the shear viscosity of nanofluids.Although the shear-thinning behaviour of the nanofluids could be partially attributed to the structuring of interacting rod-like particles,the large deviation between the measured high-shear viscosity and the predicted ones by the Brenner&Condiff equation cannot fully be interpreted.In the following,an attempt is made to explain the experimental observations from the viewpoint of aggregation of nanaoparticles,which have been shown to play a key role in thermal behaviour of nanofluids in recent studies(Wang et al. 2003;Xuan et al.2003;Nan et al.1997;Prasher et al. 2006a,b;Keblinski et al.2005).Such an approach is also supported by the SEM and dynamic lightTable1Empirical constants for Eq.(1)a Maximum discrepancies;b Minimum discrepancies Concentration(wt%)A B C MaxD a(%)MinD b(%)0.0-3.21140.86973-154.570.62-1.440.5-3.42790.94425-148.490.93-0.471.0-2.94780.81435-159.14 1.11-0.692.0-2.2930.65293-174.57 1.64-0.694.0-2.63750.7574-165.820.99-0.948.0-2.73140.93156-145.010.88-1.57scattering analyses,which,as mentioned before, show clear evidence of particle aggregation.According to the modified Krieger-Dougherty equation(Goodwin and Hughes2000;Wang et al. 2003;Xuan et al.2003;Nan et al.1997),the relative viscosity of nanofluids,g r,is given as:g r¼1Àu a=u mðÞÀ½g u mð4Þwhere u m is the maximum concentration at which the flow can occur and u a is the effective volume fraction of aggregates given by u a¼u=u ma with u ma the maximum packing fraction of aggregates.As aggre-gates do not have constant packing throughout the structure,the packing density is assumed to change with radial position according to the power law with a constant index(D).As a result,u a is given as u a¼uða a=aÞ3ÀD;with a a and a,the effective radii of aggregates and primary nanoparticles,respectively. The term D is also referred as the fractal index meaning the extent of changes in the packing fraction from the centre to the edge of the aggregates.Typical values of D are given in normal textbook as D= 1.8–2.5for diffusion limited aggregation(DLA)and D=2.0–2.2for reaction limited aggregation(RLA); see for example Goodwin and Hughes(2000).For nanofluids containing spherical nanoparticles,the value of D has been shown experimentally and numerically to be between1.6and1.8(Wang et al. 2003,Xuan et al.2003)and between1.8and2.3, respectively(Waite et al.2001).A typical value of 1.8is suggested for nanofluids made of spherical nanoparticles(Prasher et al.2006a,b).However,little research has been found on the fractal index for nanofluids containing rod-like nanoparticles.The colloid science literature suggests a fractal index of 1.5–2.45for colloidal suspensions depending on the type of aggregation,chemistry environment,particle size and shape and shearflow conditions(Haas et al. 1993;Mohraz et al.2004;Hobbie and Fry2006; Micali et al.2006;Lin et al.2007).In a recent study, Mohraz et al.(2004)investigated the effect of monomer geometry on the fractal structure of colloi-dal rod aggregates.They found that the fractal index is a non-linear function of the monomer aspect ratio with the D increasing from*1.80to*2.3when the aspect ratio of the rod-like nanoparticles increases from1.0to30.6.Based on the above,a value of D=2.1is taken for nanofluids used in this work (Mohraz et al.2004,Lin et al.2007).Although the fractal model may appear to simplify the complexity of microstructures in aggregating systems containing rod-like particles,excellent agreement between the model prediction and experimental measurements exists when a a/a=9.46;see Fig.4.Here the aggregates are assumed to formflow units of an ellipsoidal shape with an effective aspect ratio of r a¼L a=b a;where L a and b a are the effective length and diameter,respectively.In the calculation,a typical value of u m of0.3is taken(Barnes et al.1989),and the intrinsic viscosity[g]is calculated by Eq.(3).It is to be noted that the aggregate size thatfits well to the rheological data(Fig.4)is consistent with the particle size analyses using both the SEM and the Malvern Nanosizer.A comparison between the EG-TNT data (a a/a=9.46,D=2.1,u m=0.30)and the EG-TiO2 data(a a/a=3.34,D=1.8,u m=0.605)(Chen et al. 2007b)in Fig.4suggests that the larger aggregate size in TNT nanofluids be an important factor responsible for the stronger shear-thinning behaviour and higher shear viscosity of TNT nanofluids.An inspection of Eq.(4)indicates that the effec-tive volume fraction u a u a¼u a a=aðÞ3ÀDis much higher than the actual volume fraction(u).This leads to the experimentally observed high-shear viscosity even for very dilute nanofluids,according to the classification discussed before.As a consequence,the demarcations defining the dilute and semi-concen-trated dispersions should be changed by using the effective volume fraction.The model discussed above can also provide a macroscopic explanation for the temperature indepen-dence of the high-shear viscosity.From Eq.(4),one can see that the relative high-shear viscosity depends on three parameters,the maximum volume fraction, u m,the effective volume fraction,u a and the intrinsic viscosity,[g].For a given nanofluid at a temperature not far from the ambient temperature,the three parameters are independent of temperature and hence the little temperature dependence of the relative shear viscosity.Microscopically,as explained before,the temperature-independent behaviour is due to negligi-ble Brownian diffusion compared with convection in high-shearflows.To further illustrate if the proposed aggregation mechanism is adequate,it is used to predict the effective thermal conductivity of the nanofluids by using the following conventional Hamilton–Crosser model(H–C model)(Hamilton and Crosser1962):k=k0¼k pþðnÀ1Þk0ÀðnÀ1Þuðk0Àk pÞk pþðnÀ1Þk0þuðk0Àk pÞð5Þwhere k and k0are,respectively,the thermal conductivities of nanofluids and base liquid,n is the shape factor given by n=3/w with w the surface area based sphericity.For TNT used in this work,the sphericity w is estimated as0.6(Hamilton and Crosser1962).For suspensions of aggregates,the above equation takes the following form:k=k0¼k aþðnÀ1Þk0ÀðnÀ1Þu aðk0Àk aÞa0a0að6Þwhere k a is the thermal conductivity of aggregates.To calculate k a,Eq.(6)is combined with the following Nan’s model(Nan et al.2003)for randomly dispersed nanotube-based composites:k a=k0¼3þu in½2b xð1ÀL xÞþb zð1ÀL zÞ3Àu in½2b x L xþb z L zð7Þwhere/in is the solid volume fraction of aggregates, b x¼ðk xÀk0Þ=½k mþL xðk tÀk mÞ and b z¼ðk zÀk0Þ=½k mþL zðk tÀk mÞ with k x,k m and k t being the thermal conductivities of nanotubes along trans-verse and longitudinal directions and isotropic thermal conductivity of the nanotube,respectively. In this work,k x,k m and k t are taken the same value as k p for afirst order of approximation due to lack of experimental data,and L x and L z are geometrical factors dependent on the nanotube aspect ratio given by L x¼0:5r2=ðr2À1ÞÀ0:5r coshÀ1r=ðr2À1Þ3=2 and L z¼1À2L x:Figure5shows the experimental results together with predictions by the original H–C model(Eq.5) and revised H–C model(Eq.6).Here the experiment data were obtained using a KD2thermal property meter(Labcell,UK)(Murshed et al.2005;Chen et al. 2008).One can see that the measured thermal conductivity is much higher than the prediction by the conventional H–C model(Eq.5),whereas the modified H–C model taking into account the effect of aggregation(Eq.6)agrees very well with the exper-imental data.The above results suggest that nanoparticle aggregates play a key role in the enhancement of thermal conductivity of nanofluids. The results also suggest that one could use the rheology data,which contain information of particle structuring in suspensions,for the effective thermal conductivity prediction.In summary,we have shown that EG-TNT nano-fluids are non-Newtonian exhibiting shear-thinning behaviour over20–60°C and a particle mass concen-tration range of0–8%,in contrast to the Newtonian behaviour for EG-TiO2nanofluids containing spher-ical particles.The non-Newtonian shear-thinning behaviour becomes stronger at higher temperatures or higher concentrations.For a given particle concen-tration,there exists a certain shear rate(e.g.*10s-1 for4wt%)below which the viscosity increases with increasing temperature,whereas the reverse occurs above such a shear rate.The normalised high-shearviscosity with respect to the base liquid viscosity, however,is found to be independent of temperature. These observations have not been reported in the literature for nanofluids.Further analyses suggest that the temperature effects are due to the shear-depen-dence of the relative contributions to the viscosity of the Brownian diffusion and convection.The analyses also suggest that a combination of particle aggregation and particle shape effects is the mechanism for the observed high-shear rheological behaviour,which is supported not only by the particle size measurements but also by the thermal conductivity measurements and analyses using a combination of the H–C and Nan’s models.The results of this work also indicate that one could use the information of aggregation from the rheological experiments for predicting the effec-tive thermal conductivity of nanofluids. 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BIOTECHNOLOGICAL PRODUCTS AND PROCESS ENGINEERINGEffects of biotic and abiotic elicitors on cell growth and tanshinone accumulation in Salvia miltiorrhiza cell culturesJiang-Lin Zhao &Li-Gang Zhou &Jian-Yong WuReceived:7September 2009/Revised:6January 2010/Accepted:6January 2010/Published online:2March 2010#Springer-Verlag 2010Abstract This study examined the effects of biotic and abiotic elicitors on the production of diterpenoid tanshi-nones in Salvia miltiorrhiza cell culture.Four classes of elicitors were tested,heavy metal ions (Co 2+,Ag +,Cd 2+),polysaccharides (yeast extract and chitosan),plant response-signaling compounds (salicylic acid and methyl jasmonate),and hyperosmotic stress (with sorbitol).Of these,Ag (silver nitrate),Cd (cadmium chloride),and polysaccharide from yeast extract (YE)were most effective to stimulate the tanshinone production,increasing the total tanshinone content of cell by more than ten-fold (2.3mg g -1versus 0.2mg g -1in control).The stimulating effect was concentration-dependent,most significant at 25μM of Ag and Cd and 100mg l -1(carbohydrate content)of YE.Of the three tanshinones detected,cryptotanshinone was stimulat-ed most dramatically by about 30-fold and tanshinones I and IIA by no more than 5-fold.Meanwhile,most of the elicitors suppressed cell growth,decreasing the biomass yield by about 50%(5.1–5.5g l -1versus 8.9g l -1in control).The elicitors also stimulated the phenylalanine ammonia lyase activity of cells and transient increases in the medium pH and conductivity.The results suggest that the elicitor-stimulated tanshinone accumulation was a stress response of the cells.Keywords Salvia miltiorrhiza .Cell culture .Tanshinones .Elicitors .Stress responseIntroductionSalvia miltiorrhiza Bunge (Lamiaceae),called Danshen in Chinese,is a well-known and important medicinal plant because its root is an effective herb for treatment of menstrual disorders and cardiovascular diseases and for the prevention of inflammation (Tang and Eisenbrand 1992).As its Chinese name refers,Danshen root is characterized by the abundance of red pigments which are mainly ascribed to numerous diterpene quinones generally known as tanshinones,e.g.,tanshinone I (T-I),tanshinone-IIA (T-IIA),and T-IIB,isotanshinone I and II,and cryptotanshinone (CT).Tanshinones constitute a major class of bioactive compounds in S .miltiorrhiza roots with proven therapeutic effects and pharmacological activities (Wang et al.2007).Danshen in combination with a few other Chinese herbs is an effective medicine widely used for the treatment of cardiovascular diseases and used as an emergency remedy for coronary artery disease and acute ischemic stroke.According to WHO statistics,cardiovas-cular diseases are and will continue to be the number one cause of death in the world (www.who.int/cardiovascular_diseases ).It is of significance to develop more efficient means for the production of Danshen and its active constituents.Although field cultivation is currently the major produc-tion means for Danshen and most other plant herbs,plant tissue cultures provide more well-controlled and sustainable systems for efficient production of desired bioactive compounds of the herb.Plant tissue cultures are the most useful and convenient experimental systems for examiningJ.-L.Zhao :L.-G.Zhou (*)Department of Plant Pathology,China Agricultural University,Beijing 100193,China email:lgzhou@J.-Y .Wu (*)Department of Applied Biology and Chemical Technology,The Hong Kong Polytechnic University,Hung Hom,Kowloon,Hong Kong email:bcjywu@.hkAppl Microbiol Biotechnol (2010)87:137–144DOI 10.1007/s00253-010-2443-4various factors on the biosynthesis of desired products and for exploring effective measures to enhance their produc-tion.The importance of Danshen for traditional and modern medicines has promoted the long-lasting research interest in the development of tiorrhiza tissue cultures for production of bioactive compounds for more than two decades.In an early study,Nakanishi et al.(1983)induced several cell lines from plant seedlings and screened out a cell line capable of producing significant amounts of CT and another diterpene,ferruginol.In later studies,the group performed a fuller evaluation and optimization of the medium for cell growth and CT production and,eventually,derived an effective production medium with a simpler composition(ten components)than the original Murashige and Skoog(MS) medium(about20components),achieving a high CT yield of 110mg l-1(Miyasaka et al.1987).Many recent studies have been focused on hairy root cultures of tiorrhiza transformed by Agrobacterium rhizogenes(Hu and Alfermann1993;Chen et al.2001)and by our group (Zhang et al.2004;Ge and Wu2005;Shi et al.2007).Most of the bioactive compounds in medicinal plants belong to secondary metabolites which are usually less abundant than primary metabolites in the plants.Since the accumulation of secondary metabolites in plants is a common response of plants to biotic and abiotic stresses, their accumulation can be stimulated by biotic and abiotic elicitors.Therefore,elicitation,treatment of plant tissue cultures with elicitors,is one of the most effective strategies for improving secondary metabolite production in plant tissue cultures(Chong et al.2005;Smetanska2008).The most common and effective elicitors used in previous studies include the components of microbial cells especially poly-and oligosaccharides(biotic)and heavy metal ions, hyperosmotic stress,and UV radiation(abiotic),and the signaling compounds in plant defense responses such as salicylic acid(SA)and methyl jasmonate(MJ;Zhou and Wu2006;Smetanska2008).Some of these elicitors,yeast extract(mainly the polysaccharide fraction),silver ion Ag+, and hyperosmotic stress(by an osmoticum)have also been applied and shown effective to enhance the production of tanshinones in tiorrhiza hairy root cultures(Chen et al.2001;Zhang et al.2004;Shi et al.2007).To the best of our knowledge,only a few studies have been documented on the effects of elicitors,YE,SA,and MJ,on the secondary metabolite production in Agro-bacterium tumefaciens transformed tiorrhiza cell cultures from one research group(Chen and Chen1999, 2000)but not any study in normal cell cultures.The present study focuses on the effects of common biotic and abiotic elicitors including polysaccharides,heavy metal ions, SA and MJ,and osmotic stress(with sorbitol)on the growth and accumulation of three major tanshinones T-I, T-IIA,and CT in suspension culture of normal tior-rhiza cells.In addition to the effects of various elicitors on the total tanshinone content of cells,the study will examine the effects on different tanshinone species and the potential relationship to plant stress response.Material and methodsCallus induction and cell suspension cultureYoung stem explants of tiorrhiza Bunge were collected from the botanical garden at the Institute of Medicinal Plant Development,Chinese Academy of Med-ical Sciences,Beijing,China,in May2005.The fresh explants were washed with tap water,surface-sterilized with 75%ethanol for1min,and then soaked in0.1%mercuric chloride for10min and rinsed thoroughly with sterilized water.The clean and sterilized explants were cut into∼0.5-cm segments and placed on solid MS medium(Murashige and Skoog1962)supplemented with sucrose(30g l-1),2,4-D(2mg l-1)and6-BA(2mg l-1)to induce callus formation. The callus culture of tiorrhiza was maintained on a solid,hormone-free MS medium with8g l-1agar and 30g l-1sucrose at25°C in the dark and subcultured every 4weeks.The culture was deposited in Lab Y1210at The Hong Kong Polytechnic University with a collection number of Danshen cell-1.All experiments in this study were performed in suspension culture of tiorrhiza cells in a liquid medium of the same composition as for the solid culture but excluding agar.The cell suspension culture was maintained in shake-flasks,i.e.,125-ml Erlenmeyer flasks on an orbital shaker operated at110–120rpm,at 25°C in the dark.Each of the flasks was filled with25ml medium and inoculated with0.3g fresh cells from18–21-day-old shake–flask culture.Elicitor preparation and administrationEight elicitors were tested,each at three concentrations,in the initial elicitation experiments(Table1).These are representative of the four major classes of elicitors for the induction of plant responses and the stimulation of secondary metabolite production in plant tissue cultures (Zhou and Wu2006;Smetanska2008).All elicitors except MJ were prepared as a concentrated stock solution in water and autoclaved at121°C for15min,and stored at4°C in a refrigerator prior to use.Yeast elicitor(YE)was the polysaccharide fraction of yeast extract(Y4250,Sigma, St.Louis,MO,USA)prepared by ethanol precipitation as described previously(Hahn and Albersheim1978;Ge and Wu2005).In brief,yeast extract was dissolved in distilled water(20g/100ml)and then mixed with400ml of ethanol and allowed to precipitate for4days at4°C in arefrigerator.The precipitate was redissolved in100ml of distilled water and subjected to another round of ethanol precipitation.The final gummy precipitate was dissolved in 50ml of distilled water and stored at4°C before use.The concentration of YE was represented by total carbohydrate content which was determined by the Anthrone test using sucrose as a reference.Chitosan solution was prepared by dissolving0.5g crab shell chitosan(C3646,Sigma)in1ml glacial acetic acid at55–60°C for15min,and then the final volume was adjusted to50ml with distilled water and the pH adjusted to5.8with NaOH(Prakash and Srivastava 2008).MJ(Cat.39,270-7,Sigma-Aldrich)was dissolved in 95%ethanol and sterilized by filtering through a microfilter (0.2µm).SA(10,591-0,Sigma-Aldrich),sorbitol(S3755, Sigma),and the salts of heavy metals including cobalt chloride(C8661,Sigma-Aldrich),silver nitrate(S7276, Sigma-Aldrich),and cadmium chloride(C5081,Sigma-Aldrich)were dissolved in distilled water to the desired concentrations and adjusted to pH5.8.Elicitor treatment was administered to the shake–flask culture of tiorrhiza cell on day18,which was about 2–3days before reaching the stationary phase.This time point is usually favorable for elicitation when the biomass concentration is high(compared with earlier days of growth),and the cell metabolism is still active(compared with that during or after stationary phase;Buitelaar et al. 1992;Cheng et al.2006).Each of the elicitor solutions was added into the culture medium with a micropipette at the desired concentration.After the elicitor addition,the shake–flask culture of cells was maintained for another7days and then harvested for analysis.All treatments were performed in triplicate,and the results were averaged.After the initial experiments on the eight elicitors,the three most effective ones,Ag(25µM),Cd(25µM),and YE(100mg l-1)were applied in the following experiments on the time courses of elicitor-treated cell growth and tanshinone accumulation in the tiorrhiza cell culture.Measurement of cell weight,sucrose concentration, medium pH,and conductivityThe cells were separated from the liquid medium by filtration.The cell mass on the filter paper was rinsed thoroughly with water and filtered again,and blotted dry by paper towels and then dried at50°C in an oven to attain the dry weight.Sucrose concentration in the liquid medium was determined by the Anthrone test using sucrose as a reference(Ebell1969),and the medium pH and conduc-tivity were measured with the respective electrodes on an Orion720A+pH meter(Thermo Fisher Scientific,Inc., Beverly,MA,USA)and a CD-4303conductivity meter (Lutron,Taiwan),respectively.Measurement of PAL activityPhenylalanine ammonia lyase(PAL)was extracted from fresh tiorrhiza cells with borate buffer(pH8.8).The cells were ground in the buffer(0.15g ml-1)for2min with a pestle and mortar on ice,and then centrifuged at10,000rpm and4°C for20min to obtain a solid-free extract.The PAL activity was determined based on the conversion of L-phenylalanine to cinnamic acid as described by Wu and Lin(2002).Analysis of tanshinone contentsThe cell mass from culture was dried and ground into powder and extracted with methanol/dichloromethane(4:1, v/v,10mg ml-1)under sonication for60min.After removal of the solid,the liquid extract was evaporated to dryness and redissolved in methanol/dichloromethane(9:1,v/v). Tanshinone content was determined by high performance liquid chromatography(HPLC)on a HP1100system using C18column,acetonitrile/water(55:45,v/v)as the mobile phase,and UV detection at275nm as described previously (Shi et al.2007).Three tanshinone species CT,T-I,and T-IIA were detected and quantified with authentic standards obtained from the Institute for Identification of Pharmaceu-tical and Biological Products(Beijing,China).Total tanshinone content is the total content of the three tanshinones in the cells.Tanshinone content in the culture medium was negligible and not determined.ResultsCell growth and tanshinone accumulation in tiorrhiza cell cultureThe time course of tiorrhiza cell growth exhibited a lag phase or slow growth period in the first3–6days, a rapid,linear growth period between day9–18,and aTable1Elicitors and concentrations tested in the initial experiments Elicitors Unit ConcentrationC1C2C3Cobalt chloride(Co)µM 5.02550 Silver nitrate(Ag)µM 5.02550 Cadmium chloride(Cd)µM 5.02550 Salicylic acid(SA)µM1050100 Methyl jasmonate(MJ)µM1050100 Yeast elicitor(YE)mg l-150100200 Chitosan(CH)mg l-150100200 Sorbitol(SO)g l-152550stationary or declining phase in the later days,reaching the maximum biomass concentration (8.1g l -1)around day 21.The total tanshinone content of cells remained at a very low level from days 1–12and then increased steadily from days 12–27to a maximum of 0.16mg g -1.A significant portion (65%)of the tanshinone accumulation or content increase occurred during the stationary phase from days 21–27(Fig.1a ),which is characteristic of secondary metabolite production in a batch culture process.The time course of sugar (sucrose)concentration (Fig.1b )was nearly sym-metrical to that of cell growth,indicating a direct correlation of the cell growth (or biomass production)to sugar consumption.As the major carbon source,sugar was required for the S .miltiorrhiza cell growth,and when it was depleted (around day 21),the cell growth stopped,and the biomass concentration began to drop.As seen from Fig.1b ,the medium pH showed a notable drop in the first 3days (due to consumption of NH 4+and release of protons)and a gradual increase after day 6(due to consumption of nitrate NO 3-)(Morard et al.1998).Effects of various elicitors on cell growth and tanshinone productionFigure 2shows the effects of elicitor treatments on the cell growth and tanshinone accumulation in S .miltiorrhiza cell cultures,which were dependent both on the elicitor species and elicitor dose.As seen from Fig.2a ,most of the elicitor treatments except Co 2+and sorbitol at lower concentrations suppressed the cell growth to a lower biomass concentra-tion than that of the untreated control culture,and the growth suppression was more severe at a high elicitor dose.On the other hand,most of the elicitor treatments except Co 2+,sorbitol,SA,and MJ at lower concentrations increased the total tanshinone content of cell to a higher level than in the control (Fig.2b ).Overall the results indicated that the enhancement of tanshinone accumulation by an elicitor treatment concurred with a notable suppres-sion of cell growth or biomass production.Nevertheless,some of the elicitors had a much stronger stimulating effect on the tanshinone accumulation than the suppressing effect on the cell growth.In particular,Ag and Cd both at 25μM,and YE at 100mg l -1increased the total tanshinone content to 2.30mg g -1,about 11.5-fold versus that of the control (0.20mg g -1),but decreased the biomass production by no more than 50%(5.1–5.5g l -1versus 8.9g l -1).Another three elicitors,SA,MJ (both at 50μM),and sorbitol (50g l -1)increased the total tanshinone content by 2–3-fold but decreased the biomass by 30–45%compared with the control.The stimulating effect of chitosan on tanshinone accumulation (about 6-fold)was stronger than SA,MJ,and sorbitol but much weaker than Ag,Cd,and YE,while its suppressing effect on the cell growth was as severe as Ag,Cd,and YE.In summary,the results indicate that Ag,Cd,YE are the most favorable elicitors for the tanshinone production in S .miltiorrhiza cell culture and were used in the following experiments.Figure 3shows the time courses of cell growth and tanshinone production after treatment with the three most effective elicitors Ag (25μM),Cd (25μM),and YE (100mg l -1)and the control culture.All three elicitor treatments caused a steady decline of biomass concentration from initially 8.5g l -1to 5.3g l -1on day 6while biomass in00.040.080.120.160.20246810TT content (mg g -1)C e l l b i o m a s s (g d w l -1)dw TTa4.85.1 5.45.76.001020304036912151821242730p HS u c r o s e (g l -1)Culture time (d)bSucrosepHFig.1Time courses of biomass and total tanshinone content (a ),residue sugar (sucrose)and medium pH (b )in S .miltiorrhiza cell cultures (error bars for standard deviations,n =3)246810C e l l b i o m a s s (g l -1)0.00.51.01.52.02.5Control AgCdSAMJYECH SOT T c o n t e n t (m g g -1)Elicitor treatmentCo Fig.2Effects of various elicitors on biomass growth (a )andtanshinone production (b )in S .miltiorrhiza cell cultures (elicitors added to cultures on day 18at three concentrations C1,C2,and C3as shown in Table 1,and cultures harvested on day 25;error bars for standard deviations,n =3)the control culture was increased during this period (Fig.3a ).In the meantime,the tanshinone content of cells in the three elicitor-treated cultures increased sharply and most rapidly by Ag (from 0.14to 1.98mg g -1),while that of control increased slightly (from 0.14to 0.21mg g -1;Fig.3b ).The volumetric total tanshinone yields (the products of total tanshinone content and cell dry weight)were 1.9mg l -1in the control,and 9.2mg l -1,10.7mg l -1and 11.7mg l -1in cultures treated with 100mg l -1YE,25μM Cd,and Ag,respectively (on day 6).Another test was performed on the effects of two and three elicitors in combinations in the S .miltiorrhiza cell culture.As shown in Fig.4,the tanshinone content was increased about 20%with either two elicitors and about 40%with all three elicitors in combination compared with that with a single elicitor.The results suggest an additive or synergistic effect of these elicitors on the tanshinone accumulation in the cells.However,the combined use of two or three elicitors also suppressed the cell growth (biomass)more severely than with a single elicitor.Effects of elicitor treatments on different tanshinone species Of the three tanshinone species detected,CT was stimulated most significantly by all elicitors without exception;T-IIA was stimulated by most elicitors,and T-I was stimulated significantly only by chitosan but slightly stimulated or suppressed by other elicitors (Table 2).The highest CT content was about 2mg g -1(1,854–2,011μg g -1)in cellcultures treated with 25μM Ag and Cd,and 100mg l -1YE,about 31–34fold of the control level (60μg g -1),the highest T-I content 0.27mg g -1with 100mg l -1chitosan (3.4-fold of the control 80μg g -1)and the highest T-IIA content 0.37mg g -1with 25μM Cd (6-fold of the control 60μg g -1).As seen from the HPLC chromatograms (Fig.5),the cultures treated with the three different elicitors exhibited a similar profile with virtually identical major peaks.The experimental results do not suggest any specificity of particular tanshinone species to the type of elicitors,YE and chitosan as biotic polysaccharides,Cd and Ag as abiotic heavy metals,or SA and MJ as plant stress signaling pared with that of control,the HPLC profiles of elicitor-treated cultures also had three new unknown peaks appearing before the CT peak,between 10.0–11.5min and a high peak at 11.1min,which0.00.51.01.52.02.5123456T T c o n t e n t (m g g -1)Time after treatment (d)b4681012C e l l b i o m a s s (g l -1)Control Ag 25Cd 25YE 100aFig.3Time courses of biomass (a )and total tanshinone content (b )in S .miltiorrhiza cell cultures after treatment with Ag (25µM),Cd (25µM),and YE (100mg l -1;error bars for standard deviations,n =3)24681012345Cell dry weight (g l -1)T T c o n t e n t (m g g -1)Elicitor treatmentTTdwFig.4Effects of single and combined elicitors on S .miltiorrhiza cell growth and tanshinone accumulation (elicitors added to cell cultures on day 18at the same concentrations as in Fig.3,and cultures harvested on day 25;error bars for standard deviations,n =3)Table 2Effects of various elicitors on the accumulation of three tanshinones in S .miltiorrhiza cells Treatment aContent,μg/g (fold of content control)CTT-IT-IIA Control 59.9(1)81.6(1)57.6(1)Co-50263.7(4.4)67.5(0.83)55.5(0.96)Ag-251,817.5(30)71.0(0.87)225.8(3.9)Cd-251,854.0(31)80.3(0.98)369.0(6.4)SA-100390.0(6.5)78.5(0.96)72.8(1.3)MJ-100299.8(5.0)109.5(1.3)82.6(1.4)YE-1002,011.4(34)90.3(1.1)190.3(3.3)CH-100597.2(10)276.0(3.4)98.8(1.7)SO-50584.6(9.8)56.9(0.70)83.0(1.4)CT cryptotanshinone,T-I tanshinone I,T-IIA tanshinone-IIAaNumber after each elicitor symbol represents the elicitor concentra-tion as shown in Table 1may be ascribed to tanshinone relatives of higher polarity than CT induced by the elicitors.PAL activity,pH,and conductivity changes induced by elicitorsFigure 6shows the changes of intracellular PAL activity and medium pH and conductivity in the S .miltiorrhiza cell culture after the treatment by Ag (25μM),Cd (25μM),and YE (100mg l -1).The PAL activity of cells was stimulated by all three elicitors to the similar level,from 1.4-to 1.9-fold of the control level over 6days (Fig.6a ).PAL is a key enzyme at the entrance step in the phenylpropanoid pathway in plants,and its activity increase stimulated by the elicitors is suggestive of an enhanced secondary metabolism in the plant cells (Taiz and Zeiger 2006).The pH and conductivity of culture medium were also increased (to higher levels than those of the control)by all three elicitors but more significantly by YE (Fig.6b,c ).Most significant increases (differences from the control level)in the medium pH and conductivity were shown in the very early period from day 0–1.The increase in medium conductivity in the early period was most probably attributed to the release of potassium K +ion from the cells or K +efflux across the cell membrane (Zhang et al.2004).Transient medium pH increase (alkalinization)and K +efflux across the cell membrane are early and important events in the elicitation of plant responses and phytoalexin production (Ebel and Mithöer 1994;Roos et al.1998).The conductivity decline in the later period after day 1of Ag +and Cd 2+-treated cultures and the control cultures can be attributed to the consumption of inorganic and mineral nutrients in the culture medium (Kinooka et al.1991).Overall,the results here provide further evidence forthe01234R e l a t i v e P A L a c t i v i t yControl Ag CdYEa5.05.45.86.26.6M e d i u m p H b2.03.04.05.06.00246M e d i u m c o n d u c t i v i t y (m S )Time after treatment (d)cFig.6Time courses of PAL activity (a ),medium pH (b ),and conductivity (c )of S .miltiorrhiza cell cultures after elicitor treatments in comparison with the control (error bars for standard deviation,n =3)elicitor activities of Ag,Cd,and YE in stimulating the stress responses and secondary metabolism of the S. miltiorrhiza cells.DiscussionThe effects of various elicitors on tanshinone accumulation found here in the normal tiorrhiza cell cultures are in general agreement with those found in transformed cell and hairy root cultures of tiorrhiza.In transformed cell cultures(Chen and Chen1999),the CT accumulation was also stimulated significantly by YE but not by SA or MJ alone,and YE also inhibited the cell growth.The tanshinone(mainly CT)production in hairy root cultures was also enhanced significantly(3–4fold)by Ag(Zhang et al.2004)and YE(Shi et al.2007).In all these culture systems,CT was the major tanshinone species stimulated by various elicitor treatments.CT has been identified as a phytoalexin in tiorrhiza plant which plays a defense role against pathogen invasion of the plant(Chen and Chen 2000).In this connection,the stimulated CT accumulation by the elicitors may be a defense or stress response of the cells.CT was also the major diterpenoid produced by a normal tiorrhiza cell line which was initially grown in the MS medium and then transferred to a production medium containing only about half of the nutrient compo-nents of the MS medium(Miyasaka et al.1987).It is very possible that the improvement of CT yield in this production medium was also attributed,at least partially, to the stress imposed by the nutrient deficiency which suppressed growth but stimulated secondary metabolite accumulation.MJ or its relative jasmonic acid has been shown effective for stimulating a variety of secondary metab-olites in plant tissue cultures such as hypericin in Hypericum perforatum L.(St.John’s Wort)cell cultures (Walker et al.2002),paclitaxol(diterpenoid)and related taxanes in various Taxus spp.and ginsenosides in Panax spp.(Zhong and Yue2005),and bilobalide and ginkgo-lides in Ginkgo biloba cell cultures(Kang et al.2006). However,MJ showed only a moderate or insignificant stimulating effect on tanshinone accumulation in normal and transformed tiorrhiza cell cultures.The discrep-ancy suggests that the effects of various elicitors on secondary metabolite production in plant tissue cultures are dependent on the specific secondary metabolites.This argument is also supported by the much stronger stimu-lation of CT than T-I and T-IIA by most elicitors found in our tiorrhiza cell cultures.In addition,the hairy roots appeared more tolerant to the elicitor stress,and the growth was less inhibited by the elicitors or even enhanced in some cases,e.g.,by YE(Chen et al.2001)and sorbitol(Shi et al.2007).Moreover,sorbitol as an osmotic agent significantly stimulated the tanshinone accumulation(3–4folds)in tiorrhiza hairy root cultures,but not so significantly in the cell cultures.This shows that the elicitor activities for the same metabolites can vary with the tissue culture systems.In conclusion,the polysaccharide fraction of yeast extract and two heavy metal ions Ag+and Cd2+were potent elicitors for stimulating the tanshinone production in tiorrhiza cell culture.The stimulated tanshinone production by most elicitors was associated with notable growth suppression.CT was more responsive to the elicitors and enhanced more dramatically than another two tanshinones,T-I and IIA.The results from this study in the tiorrhiza cell cultures and from previous studies in hairy root cultures suggest that the cell and hairy root cultures may be effective systems for CT production, provided with the elicitors.As most of the elicitor chemicals are commercially available or can be readily prepared in the laboratory and easily administered to the cell and root cultures,they are suitable for practical applications in the laboratory or large-scale production. Acknowledgements This work was supported by grants from The Hong Kong Polytechnic University(G-U502and1-BB80)and the China Hi-Tech Research and Development Program(2006AA10A209).ReferencesBuitelaar RM,Cesário MT,Tramper J(1992)Elicitation of thiophene production by hairy roots of Tagetes patula.Enzyme Microb Technol14:2–7Chen H,Chen F(1999)Effects of methyl jasmonate and salicylic acid on cell growth and cryptotanshinone formation in Ti transformed Salvia miltiorrhiza cell suspension cultures.Biotechnol Lett 21:803–807Chen H,Chen F(2000)Effect of yeast elicitor on the secondary metabolism of Ti-transformed Salvia miltiorrhiza cell suspension cultures.Plant Cell Rep19:710–717Chen H,Chen F,Chiu FCK,Lo CMY(2001)The effect of yeast elicitor on the growth and secondary metabolism of hairy root cultures of Salvia miltiorrhiza.Enzyme Microb Technol28:100–105Cheng XY,Zhou HY,Cui X,Ni W,Liu CZ(2006)Improvement of phenylethanoid glycosides biosynthesis in Cistanche deserticola cell suspension cultures by chitosan elicitor.J Biotechnol 121:253–260Chong TM,Abdullah MA,Lai QM,Nor’Aini FM,Lajis NH(2005) Effective elicitation factors in Morinda elliptica cell suspension culture.Process Biochem40:3397–3405Ebel J,Mithöer A(1994)Early events in the elicitation of plant defence.Planta206:335–348Ebell LF(1969)Variation in total soluble sugars of conifer tissues with method of analysis.Phytochemistry8:227–233Ge XC,Wu JY(2005)Tanshinone production and isoprenoid pathways in Salvia miltiorrhiza hairy roots induced by Ag+and yeast elicitor.Plant Sci168:487–491。
课文翻译英美报刊阅读教程中级精选本第五版端木义万Lesson18
Lesson 18 Those Rugged Individuals美国个体主义价值观美国个体主义价值观No ideal may be held more sacred in America, or be more coveted by others, than the principle of individual freedom. 在美国，没有什么理想比个人自由原则更神圣，也没有什么理想比个人自由原则更令人垂涎。
更令人垂涎。
Given the chance to pursue the heart's desires, our Utopian vision claims, each of us has the ability and the right to make our dreams come true.我们乌托邦式的愿景宣称，只要有机会去追求内心的渴望，我们每个人都有能力和权利去实现自己的梦想。
和权利去实现自己的梦想。
This extraordinary individualism has prevailed as the core doctrine of the New World through four centuries, bringing with it an unrelenting pressure to prove one's self. 四个世纪以来，这种非凡的个人主义一直是新世界的核心信条，随之而来的是证明自我的无情压力。
明自我的无情压力。
The self self--made man has been America's durable icon, whether personified by the prairie homesteader or the high prairie homesteader or the high--tech entrepreneur.'白手起家的人是美国经久不衰的偶像，无论是草原上的农场主还是高科技企业家都是他们的化身。
电子信息类专业英语(西电第二版)Unit 4 Microel
Unit 4 Microelectronics
Integrated circuits are small, light, rugged, and reliable. They require less power and lower voltages than equivalent macroscopic circuits; consequently they operate at lower temperatures, and individual components may be close together without exceeding the operating temperature limit. Relatively little stray capacitance and short time delays are produced because of the short interconnections between the individual components in IC. Maintenance is simplified because if a component of the IC fails the complete IC is usually replaced. Mass production techniques of plane technology have reduced the cost of many IC so that they are almost as inexpensive as a single transistor. Eventually most conventional circuits will be replaced by IC.
［2］ The reduction in power dissipation is particularly important where a complex circuit is to be concentrated into a small space. The problem of extracting the heat generated in the circuit may then be a difficult one.
Omron Controller Link系统介绍说明书
W308-E1-1
Operations Manual for Controller Link Support Software
COMMUNICATIONS SPECIFICATIONS
ITEM
SPECIFICATION
Communication method N : N token bus
Transmission method
Messaging Service for High-Volume DataTransmission
Controller Link networks support high-volume data transfer quickly and easily with up to 2K bytes per message (including the FINS header), increasing throughput speed while reducing network traffic. This lets you transfer programs, recipes, control and production data more efficiently.
海尔热水器用户手册说明书
SENS-IN-7B 18-HD60D35-2LibraryService LiteratureProduct Section UnitaryProduct Unitary AccessoryModel T'Stats, Panels, Timers, RelaysLiterature Type Installation InstructionsSequence 7BDate January 2001File No.SV-UN-ACC-SENS-IN-7B 1/01SupersedesSENS-IN-7AZone Sensor Modulefor Heat Pump Units Dual Setpoint, Auto C/OBAYSENS09B ASYSTAT664BDescriptionThis Zone Sensor Module provides the following features and system control functions:- System control switch to select heating mode (HEAT), cooling mode (COOL) automatic selection of heating or cooling as re-quired (AUTO), Emergency Heat only (EM. HEAT), or to turn the system off (OFF).- Fan control switch to select automatic fan operation while ac-tively heating or cooling (AUTO), or continious fan operation (ON). - Dual Temperature setpoint levers for setting desired tempera-ture. The blue lever controls cooling, and the red lever controls heating.- Thermometer to indicate temperature in the zone. (This indicator has been factory calibrated.)Application- Used with Heat Pump packaged units (2 - 20 ton).Installer's GuideCustomer Property: Contains wiring and service informa-tion. Please retain.Models :Since the manufacturer has a policy of continuous product improvement,it reserves the right to change design and specifications without notice.InspectionCheck packaging and contents for damage. Check for concealed damage before storing. Report any damage immediately to the transportation company, and make any appropriate claims. Installation Steps1.Mounting location. Choose a spot on an interior wallnear the return air grille, about five feet above floor level,where air circulates freely and is of average tempera-ture for the zone.Avoid areas such as:- behind doors;- on outside walls, or any walls with unheated oruncooled areas behind the zone sensor;- in direct sunlight, or any source of radiant heat thatcould affect the temperature measurements; or- in line with the discharge air from the unit beingcontrolled.2. Mount subbase. Remove zone sensor cover from the sub-base, and mount subbase on the wall or in a 2 x 4 handy box.Route the wires through the wire access hole in the subbase.(See Figure 1) Seal the hole in the wall behind the subbase. Figure 1 - Zone Sensor Mounting (typical)Wiring!H A Z A R D O U S V O LTA G E!DISCONNECT ALL ELECTRIC POWER INCLUDING RE-MOTE DISCONNECTS BEFORE SERVICING.Failure to disconnect power before servicing can cause severe personal injury or death.Note: Guidelines for wire sizes and lengths are shown in Table 1.The total resistance of these low voltage wiresmust not exceed 2.5 ohms per conductor. Any resis-tance greater than 2.5 ohms may cause the control tomalfunction due to excessive voltage drop.Note: Do Not run low-voltage control wiring in sameconduit with high-voltage power wiring.1.Run wires. Run wires between the unit control paneland the zone sensor subbase. To determine the numberof wires required, refer to Unit IOM for Wiring Connections.2. Connect wires. Connect the wiring to the appropriateterminals at the unit control panel and at the ZoneSensor subbase. In general, zone sensor connections to the unit use the convention of connecting Zone Sensor terminals to like numbered Unit terminals (1 to 1, 2 to 2, etc.). The connec-tion detail is shown on the unit wiring diagrams which can be found in the unit service literature and on the unit.3. Replace cover. Place zone sensor cover back on thesubbase, snap securely into place.Table 1151 - 240 feet20 gauge241 - 385 feet18 gauge386 - 610 feet16 gauge611 - 970 feet14 gaugeOptional Remote Sensor (BAYSENS017)When using the optional remote sensor (BAYSENS017), mount it in the space that is to be controlled. Clip the thermistor (RT1) on the zone sensor module. Wire remote sensor to the zone sensor module according to the interconnecting wiring dia-grams in the unit's IOM.© American Standard Inc. 2001Technical Literature Printed in USA2。
1带翻译
1、1、金融用语：受取手形：应收票据；外貨ポジジョン：外汇头寸；公定歩合：法定贴现率；最割引率：再贴现率；つなぎ融資：过渡性融资；変動為替レート：浮动汇率2、股市用语：上げ幅：升幅；先安：看跌；そこを割る：跌破最低大关；持ち合い：暂告平息；軟調：疲软3、缩略语：ADBゕジゕ開発銀行（亚洲开发银行）；CIEC 国際経済協力会議（国际经济合作会议）；GA TT関税貿易一般協定（国际关税和贸易总协定）；FAO 国連食料農業機構（联合国粮农组织）；IMF 国際通貨基金（国际货币基金组织）；JICA国際協力事業団（日本国际事业协力团）OPEC石油輸出国機構（石油输出国组织）；UNDP国連開発計画（联合国开发计划署）一、经济类文章○円の国際化変動相場制の第二の不均衡は、日本の貿易収支の大幅な黒字である。
確かに第二次石油ショックの直後こそ貿易収支は赤字またはわずかな黒字だったが、数年後には大幅黒字が復活している。
79年の第二次石油ショックの後も、79－80年こそ、貿易収支は２０億ドル前後の赤字、経常収支は大幅の赤字だったが、81年以降再び黒字を増やし、83年には経常収支も黒字となった。
85年、86年は貿易収支各461億ドル、828億ドル、経常収支は各350億ドル、492億ドルの黒字である。
普通ならとっくに円高となってよさそうだが、そうならなかったのは、日本からゕメリカへ莫大な金利稼ぎの長期資本が流出したからである。
この時期の貿易黒字の急増は、日本の輸出努力とともに、ゕメリカのドル高のあおりを受けたと見るのが正しいだろう。
かつては通貨レートは貿易の動きに依存していたが、現在では、資本収支の動きが大きな影響を持つようになっている。
それだけに、貿易摩擦問題が通貨レート調整によって解決する見通しは少ない。
むしろ日本側は、経常収支の黒字を対外投資の推進に振り向け、円高を避けてきた。
实行浮动汇率制度的第二个不均衡问题是日本的贸易收支顺差大幅度。
7100系列1RU-Gen3数据中心交换机快速启动指南说明书
Chapter2 Preparation2.1Site SelectionThe following criteria should be considered when selecting a site to install the switch:•Temperature and Ventilation:For proper ventilation,install the switch where there is ample airflow to the front and back of the switch.The ambient temperature should not go below0°orexceed40°C.exceeds40°C(104°F).Pour empêcher l’interrupteur de surchauffe,ne pas utiliser il dans une zone oùla température ambiante•Airflow Orientation:Determine airflow direction of the four fan modules and two power supply modules on the rear panel.Fan and power supply module handles indicate airflow direction:•Blue Handle:Air Inlet module(port-side exhaust).•Red Handle:Air Exit module(port-side intake).Figure2-1on page6displays fan and power supply module locations on the rear panel.Their redhandles indicate that they are air exit modules.Verify that each module has the same airflowdirection.Base the switch orientation on the airflow direction of the modules to assure the air inletis always oriented toward the cool aisle:•Air Exit modules:orient the rear panel toward the hot aisle.•Air Inlet modules:orient the rear panel toward the cool aisle.If the airflow direction is not compatible with the installation site,contact your sales representativeto obtain modules that circulate air in the opposite direction.•Rack Space:Install the switch in a19"rack or cabinet.The switch height is1RU.The accessory kit provides mounting brackets for two-post and four-post racks.When mounting the switch in a partially filled rack,load the rack from bottom to top,with theheaviest equipment at the bottom.Load the switch at the bottom if it is the only item in the rack.•Power Requirements:Power requirements vary by switch and power supply model.Refer to Table1-3on page3and Table1-4on page3for information regarding your specific system.Two circuits provide redundancy protection.Section4.1describes power cable requirements.The power input plug-socket combination must be accessible at all times;it provides the primaryChapter2:Preparation Electrostatic Discharge(ESD)Precautions 2.3Electrostatic Discharge(ESD)PrecautionsObserve these guidelines to avoid ESD damage when installing or servicing the switch.•Assemble or disassemble equipment only in a static-free work area.•Use a conductive work surface(such as an anti-static mat)to dissipate static charge.•Wear a conductive wrist strap to dissipate static charge accumulation.•Minimize handling of assemblies and components.•Keep replacement parts in their original static-free packaging.•Remove all plastic,foam,vinyl,paper,and other static-generating materials from the work area.•Use tools that do not create ESD.。
Mankiw 5e Chapter 6
Mankiw 5e Chapter 6If the rate of unemployment is neither rising nor falling, then the number of people finding jobs must equal the number of peopleA. unemployed.B. losing or leaving jobs.C. looking for jobs.D. leaving the labor force.1 out of 1Correct. The answer is B. The number of people leaving jobs must equal the number of people finding jobs for the rate of unemployment to be constant. See Section 6-1.If the rate of job finding rises, the natural rate of unemployment willA. remain constant.B. increase.C. decrease.D. rise or decline, depending on the rate of job separation.0 out of 1Incorrect. The correct answer is C. As explained in Section 6-1, the higher the rate of job finding, the lower the natural rate of unemployment.Suppose that 2 percent of the employed lose their jobs each month (s = 0.02) and 38 percent of the unemployed find a job each month (f = 0.38). Then, thesteady-state rate of unemployment isA. 2 percent.B. 5 percent.C. 16 percent.D. 36 percent.1 out of 1Correct. The answer is B. As explained in Section 6-1, thesteady-state rate of unemployment is given by U = s/(s + f).The unemployment rate is 10 percent. The rate of job separation is 5 percent. How high does the rate of job finding have to be to keep the unemployment rate constant?A. 10 percentB. 45 percentC. 50 percentD. 90 percent0 out of 1Incorrect. The correct answer is B. Since 90 percent of the labor force is working and the separation rate is 5 percent, 4.5 percent of the labor force loses its job each period. For unemployment to be constant, the same fraction of the labor force must find jobs each period. See Section 6-1.Unemployment insurance schemes mainly increaseA. frictional unemployment.B. seasonal unemployment.C. teenage unemployment.D. cyclical unemployment.1 out of 1Correct. The answer is A. Since unemployment insurance programs reduce the economic hardships associated with unemployment, they increase the amount of frictional unemployment. See Section 6-2.The unemployment caused by the time that it takes to match workers and jobs is calledA. frictional unemployment.B. the discouraged-worker effect.C. structural unemployment.D. wage rigidity.1 out of 1Correct. The answer is A. For a discussion of frictional unemployment, see Section 6-2.Frictional unemployment occurs becauseA. the minimum wage is too high.B. unions exert pressure in the labor market.C. rigidities exist in the wage-setting process.D. it takes time to match firms and workers.1 out of 1Correct. The answer is D. For a discussion of frictional unemployment, see Section 6-2.Which of the following policies would reduce the amount of frictional unemployment?A. A reduction in corporate taxesB. An increase in unemployment insuranceC. An increase in the minimum wageD. Public retraining programs0 out of 1Incorrect. The correct answer is D. Public retraining programs ease the transition of workers from declining to growing industries, therebyreducing frictional unemployment. See Section 6-2.If the government increases the amount of unemployment insurance that unemployed workers can collect, the amount of frictional unemployment would be expected toA. fall.B. remain constant.C. rise.D. first rise and then fall.1 out of 1Correct. The answer is C. If the amount of unemployment insurance rises, the economic hardships of unemployed workers are reduced, so there is less incentive to search for a new job. This causes frictional unemployment to rise. See Section 6-2.When the real wage is above the level that equilibrates supply and demand, then the quantity of labor suppliedA. depends on the nominal wage.B. is smaller than the quantity of labor demanded.C. is equal to the quantity of labor demanded.D. is greater than the quantity of labor demanded.1 out of 1Correct. The answer is D. If the real wage is above its equilibrium value, labor supply will be greater than labor demand. See Section 6-3.The unemployment resulting from wage rigidity and job rationing is calledA. the natural rate of unemployment.B. the discouraged-worker effect.C. structural unemployment.D. insiders versus outsiders.0 out of 1Incorrect. The correct answer is C. For a discussion of structural unemployment, see Section 6-3.A teenager is not able to find a job because the legal minimum wage is higher than the wage that firms are willing to offer. This situation is an example ofA. frictional unemployment.B. structural unemployment.C. cyclical unemployment.D. efficient unemployment.0 out of 1Incorrect. The correct answer is B. For a discussion of structural unemployment, see Section 6-3.Minimum-wage laws are an example ofA. collective bargaining.B. wage rigidity.C. the discouraged-worker effect.D. insiders versus outsiders.1 out of 1Correct. The answer is B. Minimum wage laws prevent the nominal wage from falling below a certain level. Thus, they cause wage rigidity. See Section 6-3.Structural unemployment results whenA. the minimum wage is set to increase in the near future.B. there is generous unemployment insurance.C. workers are temporarily laid off due to weather conditions.D. the real wage is above its market-clearing level.0 out of 1Incorrect. The correct answer is D. For a discussion of structural unemployment, see Section 6-3.Which of the following is not a cause for real wage rigidity?A. Minimum-wage lawsB. Unemployment insuranceC. Union powerD. Efficiency wages0 out of 1Incorrect. The correct answer is B. For a discussion of the causes of real wage rigidity, see Section 6-3.The unemployment caused by unions and by the threat of unionization is an instance ofA. structural unemployment.B. the discouraged-worker effect.C. efficiency wages.D. conflict between insiders and outsiders.1 out of 1Correct. The answer is D. Unemployment occurs because workers already employed by a firm (insiders) fight to keep their wages high. High wages prevent the firm from hiring new workers (outsiders). See Section 6-3.Unions may cause unemployment ifA. outsiders push wages down.B. insiders force real wages higher than the market-clearing level.C. outsiders are subject to minimum-wage legislation.D. insiders are fired and outsiders are hired.1 out of 1Correct. The answer is B. Unions may force wages above their market-clearing level, causing labor supply to be higher than labor demand. The resulting form of unemployment is called "structural unemployment." See Section 6-3.Efficiency wage theories claim that firms may pay high real wages in order toA. avoid the threat of unionization.B. make workers more productive.C. discourage unskilled workers from applying.D. reduce the level of frictional unemployment.1 out of 1Correct. The answer is B. For an explanation of efficiency wage theories, see Section 6-3.Efficiency wages do not lead toA. structural unemployment.B. wages above their equilibrium level.C. lower firm profits.D. increased worker productivity.1 out of 1Correct. The answer is C. Firms pay efficiency wages in order toincrease worker productivity. This results in higher firm profits. See Section 6-3.Which of the following statements about unemployment is true?A. Most spells of unemployment are long.B. Most unemployment is accounted for by the long-term unemployed.C. The long-term unemployed make up only a small fraction of the unemployed.D. Most people who become unemployed remain unemployed for a long time.1 out of 1Correct. The answer is B. Most spells of unemployment are short, but a large fraction of the people unemployed at any given time are in long spells of unemployment. See Section 6-4.Compared to long-term unemployment, short-term unemployment is more likely to beA. frictional unemployment.B. structural unemployment.C. a result of minimum-wage laws.D. a result of union activity.1 out of 1Correct. The answer is A. Short-term unemployment is more likely to be frictional unemployment. See Section 6-4.Suppose that 130 people are unemployed for part of a given year; 120 are unemployed for 1 month, 10 are unemployed throughout the year; what percentage of total months of unemployment is attributable to the long-term unemployed?A. 7.7 percentB. 10 percentC. 13 percentD. 50 percent1 out of 1Correct. The answer is D. There are 240 total months of unemployment, of which half are short-term and half are long-term. See Section 6-4.Measured unemployment may be lower than actual unemployment becauseA. measured unemployment does not include the frictionally unemployed.B. some individuals may want a job but have become discouraged and stopped looking for one.C. some individuals claim to be unemployed when they are not looking very seriously for a job.D. measured unemployment does not include teenage unemployment.1 out of 1Correct. The answer is B. If there are individuals who want jobs, but are discouraged and no longer looking for them, actual unemployment will be higher than measured unemployment. See Section 6-4.Discouraged workers who want jobs, but have stopped looking for jobs areA. frictionally unemployed.B. unemployed due to structural unemployment.C. no longer in the labor force.D. helped by minimum-wage legislation.1 out of 1Correct. The answer is C. Individuals who are not working or actively searching for a job are not considered to be part of the labor force. See Section 6-4.Many economists believe that the rise in European unemployment is caused byA. generous government benefits.B. the decreased influence of union insiders.C. an increase in the number of younger workers who have higher rates of unemployment.D. economic inequality.1 out of 1Correct. The answer is A. Many European countries allow their unemployed to collect benefits indefinitely. This makes taking a job a less attractive alternative. See Section 6-4.。
EFM32 微控制器应用指南说明书
...the world's most energy friendly microcontrollers USART/UART - AsynchronousmodeAN0045 - Application NoteThis application note describes how to configure the EFM32 UART or USART tooperate in asynchronous mode.An included software example for the EFM32GG-DK3750 Giant Gecko DevelopmentKit shows how to implement interrupt driven receive and transmit, utilizing the on-board RS-232 transceiver.This application note includes:•This PDF document•Source files (zip)•Example C-code•Multiple IDE projects1 Universal Asynchronous Receive Transmit (UART)1.1 Basic TheoryA UART is a well established standard for low cost, low speed serial communications over a simple 2-wire (plus ground) interface.Asynchronous communications differs from synchronous communications in that synchronization between transmitter and receiver are encoded into the transmitted signal, rather than using a separate wire to transfer the transmitter clock to the receiver.Embedding the synchronization information in the data reduces the cost of cables and connectors, and may also be beneficial on a space constrained PCB or if one wants to keep the pin-usage low. On the other side adding synchronization information to the datastream increases overhead, causing the effective data rate to be lower than the baud rate.Normally, asynchronous communication modes facilitate somewhat lower data rates compared with synchronous modes. Some of the reason is the above mentioned overhead, but also because asynchronous communications may impose stronger requirements on the transceivers and the transmission lines between receiver and transmitter.Low cost and low power transceivers usually don't have advanced clock recovery mechanisms, but simply rely on the combination of oversampling and that the receiver and transmitter clock frequencies are sufficiently close.1.2 RS-232UART does not specify any electrical characteristics such as signal levels etc. Instead, several separate electrical interface standards can be applied. Most common is RS-232, but other well known standards include RS-422, RS-485, and also some standards that don't use electrical signalling such as IrDA.In this application note, the included software example uses the RS-232 transceiver that is included on the Development Kit.1.3 Using the EFM32 UART/USARTThe information necessary to configure and use the UART/USART modules on an EFM32 microcontroller are contained in the device family reference manual. This application note also presents some further details and clarifications.1.3.1 Clock SourceOften, the HFRCO is too unprecise to be used for communications. So using the HFXO with an external crystal is recommended when using the EFM32 UART/USART.In some cases, the internal HFRCO can be used. But then careful considerations should be taken to ensure that the clock performance is acceptable for the communication link.1.3.2 Baud Rate CalculationThe baud rate is given by the following expression:Baud rate(1.1)Where•br is baud rate,•f HFPERCLK is the frequency of the HFPERCLK branch of the high frequency clock tree (See figure on CMU Overview in device family specific reference manual),•OVS is the oversampling factor, and•DIV is the configurable part of the fractional divider in the UART/USART module.When rearranged, one can compute a clock divider setting that will obtain a wanted baud rate by the following formula:Clock divisor(1.2) The clock divider is a fractional divider dividing by (1+DIV/4) where DIV is a 15 bit value ranging from 0 to 32767. I.e. the clock can be divided by a factor from 1 to 8192.75. Depending on the configurable oversampling factor the baud rate is given by a further division by a factor of 4, 6, 8 or 16. This results in a baud rate that is the clock frequency divided by 4 to 131,084. If the HFXO is run at 32 MHz, baudrates between 8 Mbps and 244.11 bps can be generated as long as the HFPERCLK prescaler is set to 1.It is worth noting that the equations in this application note differs somewhat from the reference manual. The reason is that the reference manual refers to CLKDIV which is the entire 32-bit register value, of which only the 15-bit wide bitfield DIV is actually used to control the fractional divider. In this document, the bitfield DIV is consistently used.2 Software ExampleThe included software example is made for the EFM32 Giant Gecko Development Kit, EFM32GG-DK3750. However, with minor modifications the project will also work on our other EFM32 development kits. It can also be ported to the starter kits. But because the starter kits don't include RS-232 line drivers, please ensure that signal levels are compatible before establishing a communication link between two parties. Connecting the EFM32 UART directly to a PC serial port will damage the EFM32.The kit's on-board RS-232 transceiver is used to demonstrate a possible interrupt based asynchronous mode configuration of an EFM32 U(S)ART peripheral.The example uses interrupt driven transmit and receive. When transmitting a block of data, the data is first copied into a transmit queue. The U(S)ART TXBL interrupt is enabled. When the UART is ready to transmit, the TXBL interrupt goes high. The interrupt handler function fetches one byte from the transmit queue and copies it to the UART transmit buffer (UARTn->TXDATA). While transmitting, the CPU is free to perform other tasks. In the example project, the MCU spends this time in Sleep Mode (EM1).The same principle is used on receive. When an RXDATAV interrupt is received, the Rx interrupt handler copies the incoming data to a receive queue.2.1 Kit ConfigurationThe development kit's on-board RS-232 line driver is used. This transceiver is normally disconnected from the MCU, so before it can be used, it must be enabled by software. To do this, the kit library functions are used. The kit libraries are included in the kit software packages that can be installed via Simplicity Studio. Documentation can be found in a sub-folder of the Energy Micro library installation folder. It is usually located at: [energymicro]\kits\EFM32GG_DK3750\bspdoc\html\index.html where [energymicro] is the Simplicity Studio data folder. The location of this folder is system dependent, and can be found through "Simplicity Studio->File->Browse Installed Files"The RS-232 transceiver is connected to UART1, location 2 on the EFM32.2.2 InstructionsA serial cable and terminal emulator software is required to try this example. On Windows, the OpenSource terminal Tera Term can be used.First, connect a serial cable between a computer and the 9-pin RS-232 connector on the development kit. Configure the serial port as follows•Baud rate = 115 200•Data bits = 8•Parity = none•Stop bits = 1•Flow control = nonebefore opening a connection with the terminal emulator.One should also configure the terminal emulator to handle new line in the same way as the SW example.In Tera Term the proper configuration is to use LF on receive and CR+LF on transmit. If this can't be configured on the chosen emulator, the example can of course be altered to match the emulator settings.When connected, start typing. After entering some characters, press '.' which is predefined as a "termination character" causing the MCU to echo the contents of the RX queue back out on the UART.2.3 TransmitTransmit is handled by two functions: uartPutData() and UART1_TX_IRQHandler().uartPutData() copies data to send into a transmit queue. The queue is implemented as a circular buffer.The data is copied into the queue starting at the write index (wrI). When finished, the pending byte counter is updated. Finally the TX interrupt for the UART is enabled.UART1_TX_IRQHandler() reacts when the TXBL interrupt goes high, signalling that the UART transmit buffer is empty. When this happens, one byte is copied from the read index (rdI) position in the TX queue into the UART transmit buffer. The read index is updated, and the pending byte counter is decremented.If the transmit queue becomes empty, the TXBL interrupt is disabled.2.4 ReceiveIn the same way, receive is also handled by two functions: UART1_RX_IRQHandler and uartGetData.UART1_RX_IRQHandler()reacts on the RXDATAV interrupt, meaning that the UART RX buffer contains valid data. When this happens, the incoming byte is copied from the UART RX buffer into the RX queue. The queue write index (wrI) is updated, and the pending byte counter is incremented. The IRQ handler will also disable the TXBL interrupt if the transmit queue becomes empty.uartGetData() pulls a number of bytes from the receive queue. The copy starts at the read index (rdI).When data is copied, the read index is updated and the pending byte counter is decremented.Also, for the sake of the example, the RX interrupt handler checks if the received byte is a predefined termination character.3 Revision History3.1 Revision 1.032013-09-03New cover layoutRemoved unnecessary read of IF in TX IRQ Handler3.2 Revision 1.022013-05-08Added software projects for ARM-GCC and Atollic TrueStudio.3.3 Revision 1.012012-11-12Adapted software projects to new kit-driver and bsp structure.3.4 Revision 1.002012-06-28Initial revision.A Disclaimer and TrademarksA.1 DisclaimerSilicon Laboratories intends to provide customers with the latest, accurate, and in-depth documentation of all peripherals and modules available for system and software implementers using or intending to use the Silicon Laboratories products. Characterization data, available modules and peripherals, memory sizes and memory addresses refer to each specific device, and "Typical" parameters provided can and do vary in different applications. Application examples described herein are for illustrative purposes only. Silicon Laboratories reserves the right to make changes without further notice and limitation to product information, specifications, and descriptions herein, and does not give warranties as to the accuracy or completeness of the included information. Silicon Laboratories shall have no liability for the consequences of use of the information supplied herein. This document does not imply or express copyright licenses granted hereunder to design or fabricate any integrated circuits. The products must not be used within any Life Support System without the specific written consent of Silicon Laboratories.A "Life Support System" is any product or system intended to support or sustain life and/or health, which,if it fails, can be reasonably expected to result in significant personal injury or death. Silicon Laboratories products are generally not intended for military applications. Silicon Laboratories products shall under no circumstances be used in weapons of mass destruction including (but not limited to) nuclear, biological or chemical weapons, or missiles capable of delivering such weapons.A.2 Trademark InformationSilicon Laboratories Inc., Silicon Laboratories, the Silicon Labs logo, Energy Micro, EFM, EFM32, EFR, logo and combinations thereof, and others are the registered trademarks or trademarks of Silicon Laboratories Inc. ARM, CORTEX, Cortex-M3 and THUMB are trademarks or registered trademarks of ARM Holdings. Keil is a registered trademark of ARM Limited. All other products or brand names mentioned herein are trademarks of their respective holders.B Contact InformationSilicon Laboratories Inc.400 West Cesar ChavezAustin, TX 78701Please visit the Silicon Labs Technical Support web page:/support/pages/contacttechnicalsupport.aspx and register to submit a technical support request.Table of Contents1. Universal Asynchronous Receive Transmit (UART) (2)1.1. Basic Theory (2)1.2. RS-232 (2)1.3. Using the EFM32 UART/USART (2)2. Software Example (4)2.1. Kit Configuration (4)2.2. Instructions (4)2.3. Transmit (4)2.4. Receive (5)3. Revision History (6)3.1. Revision 1.03 (6)3.2. Revision 1.02 (6)3.3. Revision 1.01 (6)3.4. Revision 1.00 (6)A. Disclaimer and Trademarks (7)A.1. Disclaimer (7)A.2. Trademark Information (7)B. Contact Information (8)B.1. (8)List of Equations1.1. Baud rate (2)1.2. Clock divisor (3)。
CDS 系统管理指南说明书
Section: 3.1 Authorised Signatory For System AccessThis chapter stipulates the procedures to be complied with by the ADM with respect to authorised signatory for system access, CDS data entry supervisors list, application for User ID, application for CDS task, activate / deactivate / remove CDS User ID, change printer location, reset password, submission of reports to Bursa Malaysia Depository Sdn Bh d [“Bursa Depository”] and application to use CDS terminal/printer at Bursa Depository.The requirements of this chapter and its related appendices must be complied with at all times by the ADM.3.1Authorised Signatory For System Access3.1.1 ADM is required to submit an Authorised Signatories For System Access List(Appendix 1) to Bursa Depository.3.1.2The List should contain the following:-(s) of the authorised signatory(ies)b.Designation of the authorised signatory(ies)c.Specimen signature(s) of the authorised signatory(ies)d.E-mail address of the authorised signatory(ies).Note:ADM is allowed to furnish a maximum of five (5) authorised signatories only.3.1.3The List must be signed by the Executive Director or General Manager of theADM.3.1.4Submit the original List to Bursa Depository and a copy to Bursa Malaysia’sGroup Technology – Access Control team.3.1.5The effective date will be the date of receipt of the List from ADM or the effectivedate stated in the List, whichever is later.3.1.6If there are changes to the authorised signatory(ies), submit a fresh List to BursaDepository. The new List will supersede the previous List submitted to BursaDepository.Section: 3.2 CDS Data Entry Supervisors List3.2 CDS Data Entry Supervisors List3.2.1ADM is required to submit a CDS Data Entry Supervisors List (Appendix 2) toBursa Depository.3.2.2The responsibilities of the CDS Data Entry Supervisors are as follow:-a.Administer and monitor access(es) to WebCDSb.Supervise data entry(ies) at WebCDSc.Report erroneous entry(ies) to Bursa Depositoryd.Monitor communication with Bursa Depository through WebCDSe.Perform such other function(s) as may be directed by Bursa Depositoryfrom time to time.3.2.3The List should contain the following:-a.Primary Data Entry Supervisor’s name, designati on, direct telephonenumber and specimen signatureb.Alternate Data Entry Supervisor’s name, designation, direct telephonenumber and specimen signature.3.2.4The List must be signed by one (1) of the authorised signatories appearing in theAuthorised Signatories For System Access List.3.2.5Submit the original List to Bursa Depository.3.2.6The effective date will be the date of receipt of the List from ADM or the effectivedate stated in the List, whichever is later.3.2.7If there are changes to the Primary Data Entry Supervisor or Alternate Data EntrySupervisor, submit a fresh List to Bursa Depository. The new List will supersedethe previous List submitted to Bursa Depository.3.3 Application For User ID3.3.1Applicant duly completes and signs the User ID Application Form (Appendix 3).and converts it into PDF format, of which guidance is outlined in the User Manualfor CDS User ID Forms Entry (“CDS User Guide Manual”) (Appendix 6). Hand-written and scanned forms will be rejectedNote:(i) A user can only have one User ID / Password maintained in the systemat any point in time(ii) Username cannot be numeric or in the form of a code such as UT4088.It should be reflective of the applicant’s name.3.3.2ADM’s Authorised Signatory duly completes and signs at the approval column ofthe User ID Application Form digitally as per the CDS User Guide Manual(Appendix 6)Note:The Backdated form should not exceed one (1) month from the date received byBursa Depository.3.3.3ADM’s Authorised Signatory submits the User ID Application Form in PDFformat as per the guideline outlined in the CDS User Guide Manual (Appendix 6).3.3.4If the PDF form is not in order, Bursa Depository will reject the form to the ADMfor rectification.3.3.5Upon successful assignment of the User ID by Bursa Depository, the applicantand the ADM’s Authorised Signatory will receive an e-mail notification of UserID and password.3.3.6The ADM’s Authorised Signatory who approved the application mustacknowledge the User ID/Password Application e-mail by replying to the GroupTechnology –Access Control e-mail account with a copy to Bursa Depositorywithin 2 (two) days from the date when said email is received.3.3.7Upon receiving the User ID and password, the applicant is required to login intothe system to change the password as soon as possible.3.4 Application For CDS Task3.4.1Applicant duly completes the Task Assignment Sheet (Appendix 6a and Appendix6b) and converts into PDF format, of which guidance is outlined in the UserManual for CDS User ID Forms Entry (“CDS User Guide Manual”) (Appendix 6).Hand-written and scanned forms will be rejected.3.4.2ADM’s Authorised Signatory duly completes and signs at the approval column ofthe form digitally as per the CDS User Guide Manual (Appendix 6).3.4.3ADM’s Authorised Signatory submits the PDF form to Bursa Depository as perthe guideline outlined in the CDS User Guide Manual (Appendix 6).3.4.4If the form is not in order, Bursa Depository will reject the form to the ADM forrectification.3.4.5Ensure that the task assigned do not violate the Task Grouping as set out inAppendix 7.Note:i Group 1 task is assigned to personnel who perform monitoring andapproval functions; andii Group 2 task is assigned to personnel who perform data entry.3.4.6User having tasks from Group 1 is not allowed to have any tasks from Group 2and vice versa. Other tasks not specified in the grouping may be assigned to anyof the groups.3.4.7Applicant may check the status of his/her request from the system, two (2) marketdays after the Bursa Depository received the form.Section: 3.5 Application To Activate / Deactivate / Remove CDS User ID3.5 Application To Activate / Deactivate / Remove CDS User ID3.5.1ADM’s Authorised Signatory duly completes and signs the Application toActivate/Deactivate/Remove CDS User ID Form (Appendix 8) at the approvalcolumn of the form digitally as per the User Manual for CDS User ID FormsEntry (“CDS User Guide Manual”) (Appendix 6). Hand-written and scannedforms will be rejected.3.5.2ADM’s Authorised Signatory submits the PDF form to Bursa Depository as perthe guideline outlined in the CDS User Guide Manual (Appendix 6).3.5.3The PDF is to reach Bursa Depository at least two (2) market days before theeffective date.Note: The effective date to activate, deactivate or remove CDS User ID can bepostdated.3.5.4If the PDF form is not in order, Bursa Depository will reject the form to the ADMfor rectification.3.5.5If the form is faxed to Bursa Depository, ensure the original copy reaches BursaDepository within three (3) market days for Klang Valley’s ADM and one (1)week for outstation ADM.Note:The System Administrator will suspend the user’s User ID if the or iginalform is not received within the stipulated time.3.5.6The ADM’s Authorised E-mail Account will receive automated e-mailnotifications for activation, deactivation, and removal of CDS User ID.Section: 3.6 Application To Reset Password3.6 Application To Reset Password3.6.1Applicant duly completes Reset Password Application Form (Appendix 11) andconverts into PDF format, which guidance is outlined in the User Manual for CDSUser ID Forms Entry (“CDS User Guide Manual”) (Appendix 6). Hand-writtenform and scanned form will be rejected.3.6.2ADM’s Authorised Signatory duly completes and signs at the approval column ofthe form digitally as per the CDS User Guide Manual (Appendix 6).3.6.3ADM’s Authorised Signatory submits the PDF form as per the guideline outlinedin the CDS User Guide Manual (Appendix 6).3.6.4If the form is faxed to Bursa Depository, ensure the original copy reach BursaDepository within three (3) market days for Klang Valley’s ADM and one (1)week for outstation ADM.Note:The System Administrator will suspend the user’s User ID if the originalform is not received within the stipulated time.3.6.5Call System Administrator in order for him/her to authenticate the applicant’sidentity.3.6.6System Administrator will assign a new password and inform the applicantimmediately.Section: 3.12 Printing And Submission Of Report To Bursa Depository3.12 Printing And Submission Of Report To Bursa Depository3.12.1.ADM is required to print the Tasks Assigned To A User Report (UT520RA) onhalf-yearly basis, in the months of June and December.3.12.2.ADM is to verify the report for accuracy of tasks assigned to correct and validpersonnel.3.12.3.Ensure ADM’s Authorised Signatory has signed the report and affix the company’srubber-stamp prior to submission.Note:Failure to do so will result in the report being rejected by BursaDepository.3.12.4.The report is to reach Bursa Depository latest by 30th June and 31st Decemberrespectively.Note: Failure to do so will result in ADM’s User IDs being suspended.3.12.5.Receive acknowledgement from Bursa Depository.。
Targeted-pricing-and-customer-data-sharing-among-rivals
(2020金细1卷) The unmanned Change
(2020XX1卷) The unmanned Change China has become the first country to land a spacecraft on the far side of the moon. The unmanned Chang’e-4 probe—the name was inspired by an ancient Chinese moon goddess —______(61) (touch) down last week in the South Pole-Aitken basin. Landing on the moon’s far side is ______(62)(extreme) challenging. Because the moon’s body blocks direct radio communication with a probe, China first had to put a satellite in orbit above the moon in a spot ______(63) it could send signals to the spacecraft and to Earth. The far side of the moon is of particular ______(64) (interesting) to scientists because it has a lot of deep craters ，more so ______(65) the familiar near side. Chinese researchers hope to use the instruments onboard Ch ang’e-4 ______(66)(find) and study areas of the South Pole-Aitken basin. ＂This really excites scientists,＂Carle Pieters, a scientist at Brown University, says, ＂because it ______(67)(mean) we have the chance to obtain information about how the moon ______(68)(construct) ＂Data about the moon’s composition, such as how ______(69) ice and other treasures it contains, could help China decide whether ______(70)(it) plans for a future lunar base are practical.。
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Chapter 18Standard Template Library1. Solutions to and Remarks on Selected Programming Projects1-5. No solutions provided.6.//********************************** ******************************//// Ch18Proj6.cpp//// This program represents a document and query as a set of keywords.// It uses the binary cosine metric to then compute the similarity// between the query and document and outputs the similarity as a// value between 0 and 1.//// This program uses the generic STL set classes.//********************************** ******************************#include <iostream>#include <cstdlib>#include <cstring>#include <algorithm>#include <set>#include <iterator>#include <string>#include <cmath>#include <fstream>using namespace std;// Function prototypesvoid readFileKeywords(set<string> &setDocument, const charfilename[]);void inputKeywords(set<string>&setKeywords);// ************************// InputKeywords:// Inputs strings from the keyboard// and stores them into the set until// enter is pressed.// ************************void inputKeywords(set<string>&setKeywords){string s;cout << "Enter keywords, one per line. Enter a blank line when finished."<< endl;do{getline(cin,s);if (s != string("")){setKeywords.insert(s);}} while (s != string(""));}// ************************// ReadFileKeywords:// Opens the specified file for reading and inputs its words// into the set.// ************************void readFileKeywords(set<string> &setDocument, const charfilename[]){ifstream in_stream;string s;// Open the filein_stream.open(filename);if (in_stream.fail()){cout << "Input file opening failed." << endl;exit(-1);}// Read each word from the file until there are no morewhile (!in_stream.eof()){// Input word, ideally we should filter out// punctuation and othernon-letters but will skip now// for purposes of this assignmentin_stream >> s;setDocument.insert(s);}in_stream.close();}// ======================// main function// ======================int main(){// Variable declarationsset<string> doc1;set<string> doc2;set<string> query;readFileKeywords(doc1,"Ch11Proj12Doc1.txt");readFileKeywords(doc2,"Ch11Proj12Doc2.txt");cout << "Enter set of keywords for the query." << endl;inputKeywords(query);// The sets below are used to store the intersection.// To use the set_intersection method we need to have an// Output iterator for the intersection set. We create this // with an insert_iterator.set<string> inter1;set<string> inter2;insert_iterator<set<string> > interIter1(inter1, inter1.begin()); insert_iterator<set<string> > interIter2(inter2, inter2.begin()); // Calculates intersection for us set_intersection(doc1.begin(),doc1.end(),query.begin(),query.end(),interIter1);set_intersection(doc2.begin(),doc2.end(),query.begin(),query.end(),interIter2);// Calculate similaritydouble sim1 = inter1.size() /(sqrt(doc1.size()) *sqrt(query.size()));cout << "The similarity to document 1 is " << sim1 << endl;double sim2 = inter2.size() /(sqrt(doc2.size()) *sqrt(query.size()));cout << "The similarity to document 2 is " << sim2 << endl; return 0;}7.//********************************** ******************************//// Ch18Proj7main.cpp//// This program implements an in-memory database of books using// a vector and sorts them using the generic sort function from// the algorithm library.//********************************** ******************************#include <iostream>#include <string>#include <vector>#include <algorithm>#include <iterator>#include "Ch18Proj7.h"using namespace std;// Function prototypesvoid AddNewBook(vector<Book>&bookdata);void PrintBooks(vector<Book>&bookdata);void SortBooks(vector<Book>&bookdata);void PrintMenu();// ************************// The main function displays the menu and invokes// the proper function based on user input// ************************int main(){vector<Book> bookdata; // Vector of a class holding bookdataint i;do{PrintMenu();cin >> i;cin.ignore(); // Eat up newlineswitch (i) {case 1: AddNewBook(bookdata); break;case 2: PrintBooks(bookdata); break;}} while (i!=3);return 0;}// ************************// PrintMenu:// Displays a main menu.// ************************void PrintMenu(){cout << endl << "Select fromthe following choices:" << endl;cout << "1. Add new book" << endl;cout << "2. Print listing sorted by author (case-sensitive)" << endl;cout << "3. Quit" << endl;}// ************************// AddNewBook:// Inputs details for a new book. Creates a book object// and adds it to the end of the vector.// ************************void AddNewBook(vector<Book>&bookdata){string newName, newTitle, newDate;cout << "Enter author name: "<< endl;getline(cin, newName);cout << "Enter book title: " << endl;getline(cin, newTitle);cout << "Enter book date: " << endl;getline(cin, newDate);Book b(newName, newTitle, newDate);bookdata.push_back(b); // Store data in class}// ************************// PrintBooks:// Sorts and displays all book info.// ************************void PrintBooks(vector<Book>&bookdata){int i;// First, sort the arraySortBooks(bookdata);// Now print them allcout << "The books entered sofar, sorted by author:" << endl;for (i=0; i<bookdata.size(); i++) {cout << " " <<bookdata[i].GetAuthor() << ", " << bookdata[i].GetTitle() << ", " << bookdata[i].GetDate() << endl; }return;}// ************************// SortBooks:// Uses the built-in sortalgorithm from STL.// Note that this requires that we define the <// operator for two Book objects. // ************************void SortBooks(vector<Book>&bookdata){sort(bookdata.begin(), bookdata.end());}//********************************** ******************************//// Ch18Proj7.cpp//// This class implements storage for a single book// We will make a vector of this class in the main file.//********************************** ******************************#include <iostream>#include <string>#include "Ch18Proj7.h"// ************************// Book::Constructors// ************************ Book::Book(){author="";title="";date="";}Book::Book(string newauthor, string newtitle, string newdate) {author = newauthor;title = newtitle;date = newdate;}// ************************// Book::SetData// Method to set the author, title, date// ************************void Book::SetData(string newauthor, string newtitle, string newdate){author = newauthor;title = newtitle;date = newdate;return;}// ************************// Book::Accessors// Accessors for the author, title, date// ************************string Book::GetAuthor(){return(author);}string Book::GetTitle(){return(title);}string Book::GetDate(){return(date);}// ************************// Book::<// We must overload the < operator for the// Book class so that the sort algorithm// knows how to compare two book objects// ************************bool operator <(const Book &book1, const Book &book2){return (book1.author <book2.author);}//********************************** ******************************//// Ch18Proj7.h//// This class implements storage for a single book// We will make a vector of this class in the main file.//********************************** ******************************#include <iostream>#include <string>using namespace std;class Book{public:Book();Book(string author, string title, string date);void SetData(string author, string title, string date);string GetAuthor();string GetTitle();string GetDate();friend bool operator <(const Book &book1, const Book &book2); private:string author;string title;string date;};。