Effect of different additives on the properties of lithium alanate

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不同有机物对氯化钠溶解度和介稳区的影响

CHEMICAL INDUSTRY AND ENGINEERING PROGRESS 2017年第36卷第9期·3210·化工进展不同有机物对氯化钠溶解度和介稳区的影响卢诗谣1，赵颖颖1，2，3，袁俊生1，2，3，4（1河北工业大学海洋科学与工程学院，天津 300130；2海水资源高效利用化工技术教育部工程研究中心，天津300130；3河北省现代海洋化工协同创新中心，天津300130；4泉州师范学院化工与材料学院，福建泉州 362002）摘要：在实施废水零排放工程中，有机物的存在给无机盐结晶过程带来不利影响，因而有必要考察有机物添加剂对盐结晶的影响规律。

本文测定了氯化钠在水以及添加蛋白胨、苯酚和庚二酸的水溶液中的溶解度和超溶解度，考察了介稳区的变化规律。

结果表明，3种有机物均使氯化钠溶解度降低，且溶解度随有机物含量的增大而减小，其中庚二酸的影响最大。

3种有机物的存在也同时降低了介稳区的宽度，且随有机物含量增大而减小，影响大小顺序为苯酚＞庚二酸＞蛋白胨。

在饱和温度为343.15K 、COD 为20000mg/L 的苯酚溶液中，氯化钠介稳区宽度较纯水中相比可减小65.3%，影响效果明显。

介稳区随搅拌速率的增大、降温速率的减小而变窄。

搅拌速率在不同有机物存在下对介稳区影响大小顺序为庚二酸＞蛋白胨＞苯酚，降温速率在不同有机物存在下对介稳区影响大小顺序为蛋白胨＞苯酚＞庚二酸。

关键词：溶解性；结晶；热力学；成核；介稳区；氯化钠中图分类号：TQ013.1 文献标志码：A 文章编号：1000–6613（2017）09–3210–07 DOI ：10.16085/j.issn.1000-6613.2017-0153Study on effects of different organic compounds on solubility and metastablezone of sodium chlorideLU Shiyao 1，ZHAO Yingying 1，2，3，YUAN Junsheng 1，2，3，4（1School of Marine Science and Engineering ，Hebei University of Technology ，Tianjin 300130，China ； 2Engineering Research Center of Seawater Utilization Technology ，Ministry of Education ，Tianjin 300130，China ；3Modern MarineChemical Collaborative Innovation Center in Hebei Province ，Tianjin 300130，China ；4College of Chemical Engineeringand Materials Science ，Quanzhou Normal University ，Quanzhou 362002，Fujian ，China ）Abstract ：In the process of zero discharge of wastewater ，the existence of organic matter has an adverse effect on crystallization of inorganic salt. Therefore ，it is necessary to study the effect of organic additives on salt crystallization. The solubility ，supersolubility and variation of the metastable zone （MSZW ） of sodium chloride in pure water and aqueous solution that added peptone ，phenol and heptanediacid were measured in this paper. The results showed that the existence of the three organic matters decreases the solubility of sodium chloride. The solubility decreases with the increase of organic concentration. The effect of heptanediacid is the largest. All the organic additives doped in sodium chloride will narrow the MSZW ，and the degrees of the organic additives are in the order as follows ：phenol ＞heptanediacid ＞peptone. In the phenol aqueous solution with saturated temperature of 343.15K and COD of 20000mg/L ，the width of MSZW can be reduced by 65.3% compared with that（2015Z111）项目。

BSA_PLGA微球的制备条件优化及不同添加剂对包封率的影响

26卷6期2007年12月中　国　生　物　医　学　工　程　学　报Chinese Journal o f Biomedical Engineering V ol.26　N o.6December 2007收稿日期:2005211201,修回日期:2007201215。

基金项目:天津市重点项目(043803011);国家自然基金资助项目(50473059);博士点基金(20030023004)。

3通讯作者。

　E 2mail :s ongcx @BSA 2PL GA 微球的制备条件优化及不同添加剂对包封率的影响谷海刚1,2　金　旭1　龙大宏2　杨　菁1　王　海1　宋存先131(中国医学科学院中国协和医科大学生物医学工程研究所,天津市生物医学材料重点实验室,天津　300192)2(广州医学院组织胚胎学教研室,广州　510182)摘　要:目的　探讨不同优化条件及添加剂对BS A 2P LG A 微球包封率的影响。

方法　采用水Π油Π水(W1ΠO ΠW2)的双乳化技术制备了BS A 2P LG A 微球,对影响其包封率的工艺进行了研究并考察了蔗糖、聚乙二醇和甘油对包封率的影响。

结果　采用优化条件制备的微球包封率为8911%;BS A 溶液中加入添加剂后,包封率可以提高到9715%。

结论　采用水Π油Π水(W1ΠO ΠW2)的双乳化制备的BS A 2P LG A 微球可用于运载生物大分子药物,同时,提高内水相的粘度能够提高蛋白的包封率。

关键词:聚乳酸2聚乙二醇酸;牛血清白蛋白;微球E ffect of Formalution P arameters and Additives on BSAE ncapsulation Yields in P L G A MicrospheresG u Hai 2G ang 1,2　Jin Xu 1　Long Da 2H ong 2　Y ang Jing 1　W ang Hai 1　S ong Cun 2X ian 131(K ey Laboratory o f Biomedical Materials o f Tianjin ,Institute o f Biomedical Engineering ,Chinese Academy o f MedicalSciences &P eking Union Medical College ,Tianjin 300192)2(Department o f H istoembryology ,Guangzhou Medical College ,Guangzhou 510182)Abstract :Objective T o study the effect of some formalution parameters and additives on BS A encapsulation efficiency in P LG A m icrospheres.Methods BS A 2P LG A m icrospheres were prepared by double emulsion (W 1ΠO ΠW 2)method.The factors that affect the encapsulation efficiency of BS A in m icrospheres were determ ined and optim ized.M oreover ,the effects of sucrose ,PEG,and glycerol on BS A encapsulation efficiency were investigated.R esults The BS A encapsulation efficiency in P LG A m icrospheres made by optim ized technology was 8911%.The encapsulation efficiency was further increased to 9715%with adding sucrose ,PEG,and glycerol in BS A solution.Conclusions The P LG A m icrospheres made by (W 1ΠO ΠW 2)method could be served as carrires for the delivery of biopharmaceutical macrom olecular drugs.Increasing the viscosity of internal aqueous phase im proved entrapment efficiency of BS A 2P LG A m icrospheres.K ey w ords :poly (lactic 2co 2glycolic acid )(P LG A );bovine serum album in (BS A );m icrospheres中图分类号　R318108 文献标识码　A 文章编号025828021(2007)0620931205引言现代生物技术使大规模生产高纯度的重组蛋白或多肽类物质成为可能,这些药物为疾病的预防及治疗提供了广阔的前景。

二氧化碳水合物动力学促进剂研究进展

2018年第37卷第2期 CHEMICAL INDUSTRY AND ENGINEERING PROGRESS·517·化工进展二氧化碳水合物动力学促进剂研究进展孙贤，刘德俊（辽宁石油化工大学石油天然气工程学院，辽宁抚顺 113001）摘要：利用水合物法捕获二氧化碳是当今世界的研究热点，但其应用受到了水合物的生成条件苛刻、生成速率缓慢等问题的限制，故需要利用特定促进剂来改善水合物法分离气体的性能。

本文从动力学促进剂对二氧化碳水合物生成的影响效果和促进机理两个方面的研究进展进行了分析和介绍：在影响效果方面，主要阐述了不同类型动力学促进剂对水合物生成产生不同的影响以及在高浓度时对水合物生成产生的抑制作用，并分别分析了其原因；在促进机理方面，总结了国内外各学者的研究成果，并指出现有各种关于动力学促进剂促进机理的理论存在的不足。

此外，还提出了未来关于二氧化碳水合物动力学促进剂的发展方向：一是着重研究动力学促进剂对水合物生成促进效果与其含有基团的关系；二是目前关于动力学促进剂促进水合物生成机理还没有统一定论，这可能是由于目前的研究主要集中在促进剂对水合物外部形态的改变而未探讨促进剂对水合物内部结构的改变，因此促进剂对水合物内部结构的改变上需进一步研究。

关键词：二氧化碳；水合物；动力学；机理中图分类号：TQ022.115 文献标志码：A 文章编号：1000–6613（2018）02–0517–08 DOI ：10.16085/j.issn.1000-6613. 2017-0987Advances in carbon dioxide hydrate kinetic additivesSUN Xian ，LIU Dejun（College of Petroleum Engineering ，Liaoning Shihua University ，Fushun 113001，Liaoning ，China ）Abstract ：It is a hot topic to capture carbon dioxide by forming hydrate. However its application islimited due to the harsh formation conditions of carbon dioxide hydrate and low yield rate of hydrate. Using additives can improve hydrate separation effect. The advances in carbon dioxide hydrate kinetic additives at home and abroad were introduced and analyzed from two aspects ，the enhancement of kinetic additives on carbon dioxide hydrate generation and the mechanism of additives promoting carbon dioxide formation. For the enhancement of kinetic additives ，the effects of different types of kinetic additives on hydrate formation and the inhibitory effect on hydrate formation at high concentrations were discussed. In terms of the mechanism of additives promoting carbon dioxide formation ，the recent research results were summarized and the shortcomings of the mechanism were pointed out. In addition ，the lack of carbon dioxide hydrate kinetic additives and the future development of future researches were also discussed. The relationship between the effect of kinetic additives on hydrate formation and its containing groups needs to be further studied; secondly ，there is no unified conclusion about the mechanism of hydrate formation by kinetic additives ，which may be due to the fact that the current study focuses on the change in the external form of the hydrate and does not explore the change in the internal structure of the hydrate ，so the effect of additives on the hydrate internal structure changes needs to be further studied.Key words ：carbon dioxide ；hydrate ；kinetic ；mechanism研究。

添加剂对阴极电铜表面质量的影响

添加剂对阴极电铜表面质量的影响　Ξ蒙延双,李　坚,朱祖泽,王达健(昆明理工大学材料与冶金工程学院,云南　昆明　650093) 摘　要:研究明胶、硫脲、十二烷基磺酸钠、丙烯基硫脲及阿维同-A等作为添加剂,对阴极铜表面质量的影响。

通过目测和金相显微观察对其影响效果进行了评价。

结果表明:十二烷基磺酸钠和阿维同-A的作用效果相似,丙烯基硫脲也能明显改善电铜表面质量,有望成为铜电解工艺中的添加剂。

关键词:铜电解;添加剂;表面质量中图分类号:TG14611　文献标识码:A　文章编号:1006-0308(2002)05-0029-04The I nfluence of Additives on Surface Q uality of C athode CopperME NG Y an-shuang,LI Jian,ZH U Zu-ze,W ANG Da-jian(K unming University of Science and T echnology,K unming,Y unnan650093,China)ABSTR ACT:The in fluence of s ome additives on the quality of cathode copper has been investigated.The gelatine,thiourea,avitone-A, s odium lanrul-sulfonate and allythiourea were used as additives in investigation.The in fluencial effects are assessed with visual checking and metallo2 graphic m icroscope.The results showed that the additive s odium lanrul-sulphona and avitone-A have the sim ilar effect on im proving quality of cath2 ode copper,and allythiourea can als o im prove the sur face quality of cathode copper.KE Y WOR DS:copper electrolysis;additive;sur face quality1　引　言理论和实践均已证明,为使阴极铜表面光滑、平整、避免粒子生长;减少短路、减少阳极泥和电解液机械地粘附在阴极上的可能性,加添加剂是很必要的。

硼对纯铜的细化机理研究

硼对纯铜的细化机理研究胡新芳;邵明星;韩潇潇;武玉英【摘要】目的探究微量硼对纯铜晶粒的影响及机制.方法利用高倍视频显微镜对细化前后纯铜的铸锭组织进行观察与分析.利用热场发射扫描电子显微镜对细化前后纯铜的样品进行组织和成分分析.利用高分辨透射显微镜对样品进行微观形貌及晶体结构的分析.结果随着硼含量的增加,纯铜的晶粒明显细化.微量硼在纯铜中以单质形式存在,主要分布于晶界上.结论硼对纯铜有明显的细化效果,可显著细化纯铜的晶粒,将其晶粒细化至100 μm左右.硼对纯铜晶粒细化的机制主要是限制生长机制,在凝固过程中硼被铜晶粒排斥到晶界处,从而限制了铜晶粒的长大.【期刊名称】《精密成形工程》【年(卷),期】2018(010)006【总页数】5页(P17-21)【关键词】铜合金;晶粒细化;硼;共格【作者】胡新芳;邵明星;韩潇潇;武玉英【作者单位】国网山东省电力公司电力科学研究院,济南250002;山东电力工业锅炉压力容器检验中心有限公司,济南250002;国网山东省电力公司电力科学研究院,济南250002;山东电力工业锅炉压力容器检验中心有限公司,济南250002;山东大学材料液固结构演变与加工教育部重点实验室,济南250061;山东大学材料液固结构演变与加工教育部重点实验室,济南250061【正文语种】中文【中图分类】TG146.1铜及其合金具有优良的导电性、导热性、延展性和耐蚀性，可用于制作发电机、母线、电缆、开关装置、变压器等电工器材和热交换器、管道、太阳能加热装置的平板集热器等导热器材[1—5]。

在铜及其合金的铸锭生产过程中，经常会出现诸如偏析、气孔等缺陷，影响铸锭质量。

晶粒细化不仅能够提高材料的强度，而且能提高材料的塑性。

细化晶粒可有效控制和改善合金组织，减少偏析等缺陷，提高材料的综合性能。

目前铜合金常用的细化方法[6—11]有添加合金元素、快速凝固、形变处理和电脉冲孕育处理等，其中添加合金元素细化合金组织最为简单，在实际生产中得到广泛的应用。

scientist studying the effects of

Scientists studying the effects of various phenomena play a crucial role in expanding our understanding of the natural world, human behavior, and the complex interplay between different variables. This process involves systematic investigation, data collection, analysis, and interpretation to draw meaningful conclusions. Let's explore the broader concept of scientists studying the effects of different factors and delve into the methodologies, significance, and challenges associated with such studies.### **Introduction:**Scientists engaging in the study of effects often aim to uncover causal relationships, identify patterns, or understand the impact of certain factors on a given system. This exploration encompasses a wide range of disciplines, including physics, chemistry, biology, psychology, environmental science, and social sciences. The effects being studied can be diverse, ranging from the microscopic level of particles to the macroscopic level of ecosystems or human societies.### **Methodologies in Studying Effects:**1. **Experimental Design:**- **Controlled Experiments:** Scientists often use controlled experiments to isolate specific variables and observe their effects systematically. This involves manipulating one variable while keeping others constant.2. **Observational Studies:**-**Longitudinal Studies:** Researchers track subjects over an extended period to observe changes and identify potential causative factors.- **Cross-Sectional Studies:** Examining a diverse group at a single point in time to uncover correlations and associations.3. **Field Studies:**-**Ecological Studies:** Scientists study effects within natural environments, observing interactions between organisms and their surroundings.-**Social Science Field Studies:** Researchers may conduct surveys or interviews to understand the effects of social, economic, or cultural factors on individuals or communities.4. **Computer Modeling:**- **Simulation Studies:** Scientists use computer models to simulate real-world scenarios, allowing them to predict and analyze potential effects without real-world experimentation.### **Significance of Studying Effects:**1. **Scientific Advancement:**- **New Discoveries:** Research on the effects of various factors often leads to the discovery of new phenomena, principles, or relationships.-**Advancement of Knowledge:** Building on existing knowledge, scientists contribute to the continuous advancement of their respective fields.2. **Problem Solving:**- **Environmental Solutions:** Studying the effects of human activities on the environment aids in developing strategies for sustainable resource use and conservation.- **Medical Breakthroughs:** Understanding the effects of drugs, diseases, and lifestyle on health contributes to medical advancements and improved healthcare.3. **Policy Formulation:**-**Informed Decision-Making:** Governments and organizations use scientific studies to formulate policies addressing societal issues, such as public health, education, and environmental protection.-**Risk Assessment:** Studying the effects of potential hazards helps in assessing and mitigating risks to human health and safety.4. **Technological Innovation:**- **Materials Science:** Studying the effects of different materials on each other contributes to the development of new materials with enhanced properties.-**Engineering Advancements:** Understanding the effects of forces, temperature, and other factors on structures and systems informs engineering practices and innovations.### **Challenges in Studying Effects:**1. **Complexity of Systems:**-**Interconnected Variables:** Natural systems are often complex, with numerous interconnected variables. Isolating the effect of one variable while keeping others constant can be challenging.2. **Ethical Considerations:**- **Human Subjects:** In social and medical studies, ethical considerations, such as informed consent and the potential for harm, must be carefully addressed.-**Environmental Impact:** Researchers studying ecological effects must consider the potential impact of their studies on the environment.3. **Resource Limitations:**-**Financial Constraints:** Conducting comprehensive studies requires financial resources for equipment, personnel, and data analysis.- **Time Constraints:** Longitudinal studies, in particular, can be time-consuming, requiring sustained funding and commitment.4. **Data Interpretation:**-**Statistical Challenges:** Interpreting data and drawing meaningful conclusions require statistical expertise to avoid misinterpretation or bias.- **Correlation vs. Causation:** Distinguishing between correlation and causation is critical to avoid drawing incorrect causal relationships.### **Case Study: Studying the Effects of Climate Change:**Consider a case study where scientists are studying the effects of climate change:1. **Methodology:**- **Observational Studies:** Scientists analyze long-term climate data, including temperature records, sea-level measurements, and ice core samples.-**Computer Modeling:** Climate scientists use sophisticated models to simulate future climate scenarios based on different emission scenarios.2. **Significance:**- **Policy Impact:** Findings contribute to global efforts to mitigate climate change, shaping international agreements and policy decisions.-**Environmental Awareness:** Studying the effects raises public awareness of climate change impacts, fostering environmentally conscious behaviors.3. **Challenges:**- **Data Uncertainty:** Climate systems are intricate, and uncertainties in data interpretation can pose challenges in predicting future scenarios.- **Global Collaboration:** Studying a phenomenon as pervasive as climate change requires international collaboration and coordination.### **Conclusion:**In conclusion, scientists studying the effects of various factors contribute significantly to human knowledge, technological innovation, and policy formulation across diverse disciplines. The methodologies employed, the significance of their findings, and the challenges they face vary depending on the field of study. Despite challenges, the pursuit of understanding the effects of different variables remains integral to scientific progress and addressing global challenges.。

添加剂对聚脲润滑脂性能的影响

第44卷第2期2024 年4月辽宁石油化工大学学报JOURNAL OF LIAONING PETROCHEMICAL UNIVERSITYVol.44 No.2Apr. 2024引用格式：黎小辉,张泽,杨露露,等.添加剂对聚脲润滑脂性能的影响[J].辽宁石油化工大学学报,2024,44(2):7-13.LI Xiaohui,ZHANG Ze,YANG Lulu,et al.Effect of Additives on the Performance of Polyurea Lubricating Grease[J].Journal of Liaoning Petrochemical University,2024,44(2):7-13.添加剂对聚脲润滑脂性能的影响黎小辉1,2，张泽1，杨露露1,3，吴韦岐4，任晓辰4，马伟华5，李广涛5（1.西安石油大学化学化工学院，陕西西安 710065； 2.陕西省绿色低碳能源材料与过程工程技术研究中心，陕西西安710065； 3.西安市高碳资源低碳化利用重点实验室，陕西西安 710065； 4.西安玛珂特新材料科技股份有限公司，陕西西安710399； 5.西安石油大佳润实业（集团）有限公司，陕西西安 710003）摘要：　采用直接法制备聚脲润滑脂，考察了五种添加剂对聚脲润滑脂极压抗磨性能的影响。

结果表明，五种添加剂均与聚脲润滑脂具有良好的相容性，且对聚脲润滑脂的胶体安定性等基本无影响，并可增强其热稳定性；添加剂可显著强化聚脲润滑脂的极压抗磨性，含硫磷的复合多效添加剂对聚脲润滑脂极压抗磨性能的提升作用相对较好。

研究结果可为聚脲润滑脂极压抗磨性能的改善提供可参考的基础，使其综合性能达到相对最优，从而增强聚脲润滑脂在高负荷、高速机械设备等苛刻工况下的实际使用性能。

关键词：　添加剂；　聚脲润滑脂；　性能指标；　极压抗磨性中图分类号： TQ626.4 文献标志码：A doi：10.12422/j.issn.1672⁃6952.2024.02.002Effect of Additives on the Performance of Polyurea Lubricating GreaseLI Xiaohui1,2，ZHANG Ze1，YANG Lulu1,3，WU Weiqi4，REN Xiaochen4，MA Weihua5，LI Guangtao5（1.College of Chemistry and Chemical Engineering， Xi'an Shiyou University， Xi'an Shaanxi 710065， China；2.Shaanxi Engineering Research Center of Green Low⁃Carbon Energy Materials and Processes， Xi'an Shaanxi 710065， China；3.Xi'an Key Laboratory of Low⁃Carbon Utilization for High⁃Carbon Resources， Xi'an Shaanxi 710065， China；4.Xi'an Market New Materials Technology Co. Ltd.， Xi'an Shaanxi 710399， China；5.Xi'an Petroleum Dajiarun Industry （Group） Co. Ltd.， Xi'an Shaanxi 710003， China）Abstract:　The direct method was used to prepare polyurea lubricating grease, and the effects of several different types of additives on the extreme pressure and anti⁃wear performance for polyurea lubricating grease were investigated and studied. The results demonstrate that several types of additives have good compatibility with polyurea grease, and they have little undesirable influence on colloidal stability of polyurea grease, and they can also enhance thermal stability of polyurea grease. Moreover, the addition of additives can significantly improve the performance of extreme pressure and wear resistance for polyurea lubricating grease. And in the experiments, it was found that the composite multifunctional additive containing sulfur and phosphorus has a relatively better effect on improving the extreme pressure and wear resistance of polyurea lubricating grease. The research results can provide a reference basis for the improvement of extreme pressure and anti⁃wear property for polyurea lubricating grease, achieving a relatively optimized comprehensive performance, thereby enhancing its practical utilization performance under the harsh working conditions for high load and high speed mechanical equipment.Keywords:　Additives； Polyurea lubricating grease； Performance indicators； Extreme pressure and wear resistance自1954年聚脲润滑脂被首次开发成功以来，就以高滴点、高稳定性迅速成为高性能润滑脂的典型代表，被广泛应用于冶金、汽车轴承、航空航天等领域[1⁃4]。

不同干燥条件对生姜品质的影响

中国食品添加剂China Food Additives试验研究收稿日期：2020-05-28 *通讯作者作者简介：李晴晴（1994-），女，硕士，研究方向为食品工程。

不同干燥条件对生姜品质的影响李晴晴，魏占姣，李记龙，武亚明，齐立军*（晨光生物科技集团股份有限公司，邯郸 057250）摘要：以云南罗平小黄姜为原料，以水分、挥发油、姜辣素含量及外观变化情况为指标，研究了干燥温度及切片厚度对生姜干燥后品质的影响，确定了生姜较优干燥条件为温度140～160℃，切片厚度3～5mm 。

同时与市售干姜的挥发油、姜辣素及6-姜酚含量作比较。

结果表明，试验所得干姜有效成分含量高于市售干姜，说明干姜干燥条件及干燥形态对干姜品质有不同程度的影响。

关键词：生姜；干燥；水分；挥发油；姜辣素中图分类号：TS205.1 文献标识码：A 文章编号：1006-2513（2020）12-0001-05doi ：10.19804/j.issn1006-2513.2020.12.001Effect of different drying conditions on ginger qualityLI Qing-qing ，WEI Zhan-jiao ，LI Ji-long ，WU Ya-ming ，QI Li-jun *（Chenguang Biotechnology Group Co.，Ltd.，Handan 057250）Abstract ：The effects of drying temperature and slice thickness on the quality of dried ginger were studied by using Yunnan Luoping small turmeric as raw material ，and water ，essential oil ，gingerol content and appearance change were chosen as indexes. The optimum drying conditions of ginger were determined as temperature 140～160℃ and slice thickness 3～5mm. Meanwhile ，the contents of volatile oil ，gingerol and 6-gingerol were compared with those of commercially available dried ginger. The results showed that the content of active ingredients in dried ginger was higher than that in the market ，which indicated that the drying conditions and thickness had different effects on the quality of dried ginger.Key words ：ginger ；dry ；moisture ；essential oil ；gingerol生姜中含有多种功能活性成分，如姜辣素、姜烯酚和姜酮等水溶性多酚类化学成分，姜油等挥发性成分，嘌呤类化合物，活性多糖类和糖蛋白等［1-2］，具有温中散寒、回阳通脉、温肺化饮、抗氧化、抗炎以及解热的特殊功效［3］。

Effect of Additives on the Activity of Tannase from Aspergillus awamori MTCC9299

Effect of Additives on the Activity of Tannasefrom Aspergillus awamori MTCC9299Vinod Chhokar &Meenakshi Sangwan &Vikas Beniwal &Kiran Nehra &Kaur S.NehraReceived:2April 2009/Accepted:4October 2009/Published online:21October 2009#Humana Press 2009Abstract Tannase from Aspergillus awamori MTCC 9299was purified using ammonium sulfate precipitation followed by ion-exchange chromatography.A purification fold of 19.5with 13.5%yield was obtained.Temperature of 30°C and pH of 5.5were found optimum for tannase activity.The effects of metals and organic solvents on the activity of tannase were also studied.Metal ions Mg +2,Mn +2,Ca +2,Na +,and K +stimulated the tannase activity,while Cu +2,Fe +3,and Co +2acted as inhibitors of the enzyme.The addition of organic solvents like acetic acid,isoamylalcohol,chloroform,isopropyl alcohol,and ethanol completely inhibited the enzyme activity.However,butanol and benzene increased the enzyme activity.Keywords Tannase .DEAE-cellulose .Organic solvents .Metal ions .Aspergillus awamori MTCC 9299IntroductionTannase (tannin acyl hydrolase,EC 3.1.1.20)is an inducible enzyme that catalyzes the hydrolysis of ester and depside bonds in hydrolyzable tannins by releasing glucose and gallic acid [1,2].Gallic acid finds application in many fields like dye making,pharmaceuticals,leather,and chemical industries.Besides gallic acid production,the enzyme is extensively used in the preparation of instant tea,wine,beer,and coffee-flavored soft drinks and also as additive for detannification of food.A potential use of tannase is in Appl Biochem Biotechnol (2010)160:2256–2264DOI 10.1007/s12010-009-8813-7V .Chhokar (*):V .BeniwalDepartment of Bio and Nano Technology,Guru Jambheshwar University of Science and Technology,Hisar 125001Haryana,Indiae-mail:vinodchhokar@M.Sangwan :K.NehraDepartment of Biotechnology,Choudhary Devilal University,Sirsa 125055Haryana,IndiaK.S.NehraDepartment of Biotechnology,t.College,Adampur 125052(Haryana,Indiathe treatment of waste water contaimination with polyphenolic compounds such as tannic acids and as an analytical probe for determining the structures of naturally occurring gallic acid esters[3,4].The Aspergillus species produces a large variety of extracellular enzymes,of which tannases are of significant industrial importance.As each industrial application may require specific properties of the biocatalysts,there is still an interest in finding new tannases that could find novel applications.There are several reports on the production of tannase[5],but there are only a few reports on the detailed characterization,i.e.,the effect of additives such as metal ions,cations,anions,surfactants,reducing agents,chelators,organic solvents,etc. on the enzyme activity[6].Organic solvents can be advantageous in various industrial enzymatic processes, e.g.,the reaction media used in biocatalytic esterification and transesterification contains less than1%water.The use of organic solvents can increase the solubility of nonpolar substrates,increase the thermal stability of enzymes,decrease water-dependent side reactions,or eliminate microbial contamination[7].Keeping this in view, the effect of additives such as metal ions,organic solvents,etc.on the activity of tannase from Aspergillus awamori MTCC9299was investigated.Materials and MethodsMicroorganism and Maintenance of CultureA tannase-producing fungus was isolated from the soil sample collected from Guru Jambheshwar University of Science and Technology campus.Soil sample(1g)was dissolved in10ml sterile distilled water.Of this,1ml was inoculated into potato dextrose broth containing0.5%tannic acid and incubated at30°C for72h.Aliquots from this were plated on agar plates containing0.2%tannic acid.Fungus colony capable of forming clear zone around the mycelium due to the hydrolysis of tannic acid was selected and purified. Selected strain was then morphologically identified as A.awamori MTCC9299by Microbial Type Culture Collection,Institute of Microbial Technology,Chandigarh,India.The strain was maintained on potato dextrose agar slants in a refrigerator at4°C by regular transfers.Preparation of Spore InoculumFungal spore inoculum was prepared by adding2.5ml of sterile distilled water containing 0.1%Tween80to a fully sporulated culture.The spores were dislodged using a sterile inoculation loop under strict aseptic conditions,and the number of spores in the suspension was determined using the Neubauer chamber.The volume of1ml of the prepared spore suspension was used as the inoculum with concentration of5×109spores. Fermentation MediumFor the fermentation process,a250-ml Erlenmeyer flask with50ml of Czapek Dox minimal medium containing(gram per liter):NaNO3,6;KH2PO4,1.52;KCl,0.52;MgSO4. 7H2O,0.52;FeSO4.7H2O,0.01;and ZnSO4.7H2O,0.01was employed[8].The medium was adjusted to pH5.0and then sterilized at121°C for15min.Tannic acid solution was prepared separately,and the solution was adjusted to pH5.0with0.1M NaOH,then sterilized by filtering through a sterile millipore membrane(pore size0.2µm)and added to the medium to have a final tannic acid concentration of1%.Tannase AssayTannase activity was determined colorimetrically using the method of Mondal[9].The reaction mixture contained0.3ml of tannic acid(0.5%in0.2M sodium acetate buffer,pH5.5)and 0.1ml of enzyme and was incubated at30°C for20min.The enzymatic reaction was stopped by addition of3ml of BSA solution,which precipitates the remaining tannic acid. The tubes were centrifuged(5,000×g10min),and the resultant precipitate was dissolved in a 3-ml SDS-triethanolamine solution.A1ml of FeCl3reagent was added to each tube and was kept for15min at room temperature for stabilization of the color.The absorbance was read at 530nm against the blank.One unit of enzyme activity is defined as the amount of enzyme required to hydrolyze1mM of tannic acid in1min under assay conditions.Assay of Protein ConcentrationThe protein concentration was determined by the Bradford method[10]using bovine serum albumin as the standard.Purification of TannaseSupernatants from batch cultures were concentrated using ammonium sulfate fractionate and dialyzed against acetate buffer(0.02M and pH5.5)at4°C.The resultant enzyme solution was loaded onto2.5×10cm DEAE-cellulose column equilibrated with0.02M acetate buffer(pH 5.5),and the proteins were eluted with a linear gradient of0.0–0.5M NaCl at a flow rate of5ml/h. The fractions of2ml each were collected and analyzed for enzyme activity.Fractions with high enzyme activity(fraction number4and5)were pooled together and used for further experiments.SDS-PAGE and Molecular Weight(Mr)DeterminationThe comparative mobility of partially purified and purified tannase was carried out on7.5% SDS-PAGE.Molecular weight markers were purchased from Sigma and were run parallel to the samples.Enzyme CharacterizationThe effect of different temperatures,pH,organic solvent,and metal ions on the enzyme fractions obtained after DEAE-cellulose chromatography was studied.Optimum pH and Temperature for Tannase ActivityThe optimum pH for tannase activity was determined at30°C by incubating the enzyme with substrate at different pH ranges from3to6.The pH of the reaction mixture was varied using different buffers(acetate buffer for pH3.5–5.5and phosphate buffer for pH6).The optimum temperature was determined by incubating the reaction mixture for20min at different temperatures ranging from20to70°C.Effect of Organic Solvents and Metals IonsThe enzyme solution containing different concentrations(20%,40%,and60%)of various organic solvents(acetone,toluene,benzene,ethanol,acetic acid,isoamylalcohol,chloroform,phenol,butanol,and glycerol)and1mM concentration of various metal ions like Ca+2,Na+,K+,Mn+2,Fe+3,Zn+1,Co+2,Cu+2,and Mg+2were incubated(acetate buffer 0.2M,pH5.5)at30°C for20min,and the effect of organic solvents and metal ions on tannase activity was studied.Results and DiscussionPurification of TannaseAmmonium sulfate fractionation was done at various concentrations(50–90%).Recovery of enzyme was maximum at80%fractionation.The elution profile of tannase from the DEAE-cellulose column filtration is shown in Fig.1.The elution profile of the enzyme showed two peaks.Maximum tannase activity was found at the first peak.The active fraction(fraction number4and5)were pooled.DEAE-cellulose column chromatography led to an overall purification of19.5-fold with a yield of13.5%(Table1).Mahendran et.al.[11]and Kasieczka-Burnecka et.al.[12]also obtained similar values after DEAE-cellulose column chromatography of tannase from Paecilomyces variotii and Verticillium sp.P9, respectively.However,a purification fold of135with91%yield of tannase from Penicillium variable has also been reported using gel-filtration chromatography[13].SDS-PAGE and Molecular Weight(Mr)DeterminationFigure2shows the molecular mass of purified tannase obtained from SDS-PAGE analysis, with a single band of101±2kDa indicating the homogeneity of the enzyme.Tannases reported so far are generally of high molecular weight ranging from80to310kDa[11–13]. Tannase from Aspergillus niger ATTC16620have been reported as a single monomer unit of149kDa[14].Tannase from Aspergillus flavus and A.niger N888has also been reported as single peptide of80–85and165kDa,respectively[14].However,the molecular weight of P.variable tannase has been reported to be310kDa with a dimer of two subunit of158kDa[13].Fig.1Elution graph ofion-exchange chromatographyEffect of pH and Temperature on the Activity of EnzymeEffect of initial pH (Fig.3)of the reaction mixture on the tannase activity showed that the activity is extremely low at pH 3.0(1.63U/ml).The activity of enzyme increased gradually with increase in pH peaking at pH 5.5(2.88U/ml).Further increase in pH resulted in decrease in the activity of tannase.To evaluate the effect of temperature on the activity of purified tannase,the temperature was varied from 25to 70°C.With an increase in temperature,the tannase activity increased,and optimum activity was recorded at 30°C (Fig.4).These results are in agreement with the previous reports of pH 5.5for Aspergillus ruber [15]and a pH range of 5–7for P .variotii [11].The optimum temperature for tannase activity was 30°C,which was similar to those obtained for Lactobacillus plantarum CECT748[16].However,optimum temperature and pH of tannase from A.awamori Nakazawa have been reported to be 35°C and pH 5.0,respectively [2].Effect of Organic Solvents on Enzyme ActivityIn nature,enzymes function in aqueous solutions.Therefore,it is not surprising that virtually all studies in enzymology so far have used water as the reaction medium.However,from the biotechnological standpoint,there are numerous advantages of conducting enzymatic Table 1Purification table of tannase from A.awamori MTCC 9299.Source Total activity Total protein (mg)Specific activity(µ/mg)Purification (fold)Yield (%)Crude 128261.00.4891100Ammonium sulfate purification 37.1241.70.891.8229Ion exchange17.28 3.769.5519.513.5Chromatography Lane1 Lane2 Lane3 Fig.2Molecular mass of puri-fied A.awamori MTCC 9299tannase estimated by electropho-ne 1shows markerproteins (kilodalton);lane 2shows purified tannase (101±2kDa molecular mass);and lane 3shows partially purified tannase(ammonium sulfate precipitation)conversions in organic solvents as opposed to water:(1)high solubility of most organic compounds in nonaqueous media;(2)ability to carry out new reactions impossible in water because of kinetic or thermodynamic restrictions;(3)greater stability of enzymes;(4)relative ease of product recovery from organic solvents as compared to water;and (5)the insolubility of enzymes in organic media,which permits their easy recovery and reuse and,thus,eliminates the need for immobilization [17].To determine the effect of organic solvents on the activity of tannase,various organic solvents (Table 2)were used at different concentrations (20%,40%,and 60%).It was found that acetic acid,isoamylalcohol,chloroform,and isopropyl alcohol completely inhibited the activity of tannase at all concentrations.However,ethanol inhibited the tannase activity by 48.84%initially;thereafter,complete loss in the enzyme activity was observed at 40%and 60%.A gradual decrease in the activity of tannase was observed with the increasing concentration of acetone and toluene,and finally,at 60%,the activity was reduced to 55.01%and 28.49%,respectively.With the initial inhibitory effect at 20%and 40%methanol,the original activity was regained at 60%.It was also observed thatthe Fig.3Effect of pH on tannaseactivity Fig.4Effect of temperature ontannase activitypresence of butanol and benzene increased the enzyme activity by twofold at 60%v /v concentration.Sharma et.al.[13]have also studied the effect of organic solvents on tannase from P .variable and reported more than 60%residual activity in 20%v /v of carbon tetrachloride,heptane,petroleum ether,and toluene after 60min.They also observed that the enzyme was stable more than 50%in 60%v /v of carbon tetrachloride,heptane,petroleum ether,and toluene for 5min.Saborowski et.al [7]studied the effect of organic solvents on endopeptidases and found that the chymotrypsin and protease activity were slightly elevated at 5%and 10%concentration of acetone,2-propanol,methanol,and ethanol,respectively.Trypsin activity,in contrast,was strongly elevated by organic solvents;the activity rose concomitantly to eightfold of initial value at a concentration of 40%of 2-propanol.Fridovichi [18]reported that in most of the cases,the organic solvents acted as competitive inhibitors at low concentrations and became increasingly noncompetitive as the concentration of the solvent was raised.Effect of Metal Ions on Enzyme ActivityVarious metal ions like ZnSO 4,MgSO 4,CaCl 2,CuSO 4,MnSO 4,Fe 2(SO 4)3,CoCl 2,NaCl,and KCl at 1mM concentration each were tested for their effect on tannase activity.Table 3Table 2Effect of organic solvents on tannase activity.Control100%Concentration (v /v ;%)20%40%60%Acetone78.51±0.9463.92±0.9455.01±0.84Butanol163.86±1.14203.74±2.07199.44±3.16Benzene138.76±0.48127.53±1.12199.44±1.21Toluene86.66±2.6982.67±1.5228.49±1.21Acetic acid−−−Methanol54.62±2.6076.68±5.94100.31±0.54Ethanol51.16±1.14−−Chloroform−−−Isopropyl alcohol−−−Isoamyl alcohol −−−AdditivesRelative activity (%)Control100ZnSO 496.52±0.2MgSO 4123.99±0.22CoCl28.86±0.85Cu SO 448.79±1.33MnSO4115.23±1.07Fe SO 423.11±0.44CaCl2116±0.57NaCl111.45±0.89KCl 109.89±1.13Table 3Effect of metal ions ontannase activity.shows that among all the metal ions studied Mg+2,Mn+2,Ca+2,Na+,and K+elevated the tannase activity by23.9%,15.23%,16%,11%,and9%,respectively.Zn+2did not show any significant effect on tannase.Cu+2,Fe+3,and Co+2were found to be strongly inhibiting the tannase activity by51.21%,76.89%,and71.14%,respectively.The effect of metal ions on tannase activity was studied by Kar et.al.[6].Mg+2or Hg+(1.0mM)activated tannase activity;on the other hand,Ba+2,Ca+2,Zn+2,Hg+2,Ag+,Fe+3,and Co+2inhibited tannase activity at1.0-mM concentration.Mukherjee and Banerjee[4]found that the presence of the divalent ion Mg+2at low concentration increases tannase activity, whereas,it was inhibited maximally by Hg++followed by Fe+3,Zn+2,and Ba+2.Sabu et.al.[14]also studied effect of metal ions on tannase from A.niger ATCC16620and found that the addition of metal ions like Zn+2,Mn+2,Cu+2,Ca+2,Mg+2,and Fe+2inhibited the enzyme activity.Kasieczka-Burnecka et.al.[12]have recently reported inhibitory effect of Zn+2,Cu+2,K+,Cd+2,Ag+,Fe+3,Mn+2,Co+2,Hg+2,Pb+2,and Sn+2on tannase from Verticillium sp.References1.Lekha,P.K.,&Lonsane,B.K.(1997).Production and application of tannin acyl hydralose:state of theart.Advances in Applied Microbiology,44,215–260.2.Mahapatra,K.,Nanda,R.K.,Bag,S.S.,Banerjee,R.,Pandey,A.,&Szakacs,G.(2005).Purification,characterization and some studies on secondary structure of tannase from Aspergillus awamori nakazawa.Process Biochemistry,40,3251–3254.3.Seth,M.,&Chand,S.(2000).Biosynthesis of tannase and hydrolysis of tannins to gallic acid byAspergillus awamori—optimisation of process parameters.Process Biochemistry,36,39–44.4.Mukherjee,G.,&Banerjee,R.(2006).Effects of temperature,pH and additives on the activity oftannase produced by a co-culture of Rhizopus oryzae and Aspergillus foetidus.World Journal of Microbiology&Biotechnology,22,207–211.5.Aguilar,C.N.,&Gutierrez-Sanchez,G.(2001).Review:sources properties,applications and potentialuses of tannin acyl hydrolase.International Journal of Food Science&Technology,7,373–382.6.Kar,B.,Banerjee,R.,&Bhattacharyya,B.C.(2003).Effect of additives on the behavioural properties oftannin acyl hydrolase.Process Biochemistry,38,1285–1293.7.Saborowski,R.,Sahling,G.,Navarette del Toro,M.A.,Walter,I.,&Garcia-Carreno,F.L.(2004).Stability and effects of organic solvents on endopeptidases from thegastric fluid of the marine crab Cancer pagurus.Journal of Molecular Catalysis.B,Enzymatic,30,109–118.8.Bradoo,S.,Gupta,R.,&Saxena,R.K.(1996).Screening for extracellular tannase producing fungi:development of a rapid and simple plate assay.Journal of General and Applied Microbiology,42,325–329.9.Mondal,K. C.,Banerjee, D.,Jana,M.,&Pati, B.R.(2001).Colorimetric assay method fordetermination of the tannase activity.Analytical Biochemistry,295,168–171.10.Bradford,M.M.(1976).A rapid and sensitive method for the quantitation of microgram quantities ofprotein utilizing the principle of protein-dye binding.Analytical Biochemistry,72,248–254.11.Mahendran,B.,Raman,N.,&Kim,D.J.(2006).Purification and characterization of tannase fromPaecilomyces variotii:hydrolysis of tannic acid using immobilized tannase.Applied Microbiology and Biotechnology,70,444–450.12.Kasieczka-Burnecka,M.,Karina,K.,Kalinowska,H.,Knap,M.,&Turkiewicz,M.(2007).Purificationand characterization of two cold-adapted extracellular tannin acyl hydrolases from an Antarctic strain Verticillium sp.P9.Applied Microbiology and Biotechnology,77,77–89.13.Sharma,S.,Agarwal,L.,&Saxena,R.K.(2008).Purification,immobilization and characterization oftannase from Penicillium variable.Biores Technology,99,2244–2251.14.Sabu,A.,Kiran,S.G.,&Pandey,A.(2005).Purification and characterization of tannin acyl hydrolosefrom Aspergillus niger ATCC16620.Journal of Food Technology and Biotechnology,2,133–138. 15.Kumar,R.,Sharma,J.,&Singh,R.(2007).Production of tannase from Aspergillus ruber under solid-state fermentation using jamun(Syzygium cumini)leaves.Microbiological Research,162,384–390.16.Rodriguez,H.,Rivas,B.,Gomez-Cordoves,C.,&Munoz,R.(2008).Characterization of tannaseactivity in cell free extracts of Lactobacillus plantarun CECT748.International Journal of Food Microbiology,121,92–98.17.Zaks,A.,&Klibnov,A.M.(1985).Enzyme-catalyzed processes in organic solvents.Proceedings of theNational Academy of Sciences of the United States of America,82,3192–3196.18.Fridovichi,I.(1996).Some effects of organic solvents on the reaction kinetics of milk xanthine oxidase.Journal of Biological Chemistry,241,3624–3629.。

高效液相色谱法-综述

Journal of Chromatography A,1217(2010)858–880Contents lists available at ScienceDirectJournal of ChromatographyAj o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /c h r o maReviewThe challenges of the analysis of basic compounds by high performance liquid chromatography:Some possible approaches for improved separationsDavid V.McCalley ∗Centre for Research in Biomedicine,University of the West of England,Frenchay,Bristol BS161QY,UKa r t i c l e i n f o Article history:Available online 3December 2009Keywords:HPLCBasic compounds Stationary phases Reversed-phase HILICa b s t r a c tThis review considers some of the difﬁculties encountered with the analysis of ionised bases using reversed-phase chromatography,such as detrimental interaction with column silanol groups,and over-loading which both lead to poor peak shapes.Methods of overcoming these problems in reversed-phase (RP)separations,by judicious selection of the column and mobile phase conditions,are discussed.Hydrophilic interaction chromatography is considered as an alternative method for the separation of some basic compounds.©2009Elsevier B.V.All rights reserved.Contents 1.Introduction.........................................................................................................................................8592.Choice of column....................................................................................................................................8592.1.Column testing procedures..................................................................................................................8592.2.The Tanaka test and the Snyder hydrophobic subtraction parison of results with direct peak shape measurements...8602.3.Monolithic silica columns ...................................................................................................................8632.4.Slow column equilibration.Anion-exchange behaviour of alkylsilica RP columns e of column materials other than silica...................................................................................................8653.Choice of mobile phase..............................................................................................................................8663.1.Choice of modiﬁer ...........................................................................................................................8663.2.Choice of mobile phase pH.Problem of reduced retention of bases at low pH.............................................................8664.Overloading .........................................................................................................................................8674.1.Overview of the problem....................................................................................................................8674.2.Possible causes of overloading ..............................................................................................................8684.3.Effect of buffer anion on overload...........................................................................................................8704.4.Overloading on mixed-mode reversed-phase/cation-exchange columns..................................................................8714.5.Effect of buffer pH on overloading ..........................................................................................................8715.Temperature effects.................................................................................................................................8736.Hydrophilic interaction chromatography (HILIC)..................................................................................................8747.Concluding remarks.................................................................................................................................8787.1.Overloading..................................................................................................................................8787.2.Selection of mobile phase pH................................................................................................................8787.3.Quality and choice of column ...............................................................................................................8797.4.Temperature.................................................................................................................................8797.5.Alternative separation mechanisms—e.g.HILIC.............................................................................................879References...........................................................................................................................................879DOI of original article:10.1016/j.chroma.2009.11.067.∗Tel.:+441173282469;fax:+441173282904.E-mail address:david.mccalley@0021-9673/$–see front matter ©2009Elsevier B.V.All rights reserved.doi:10.1016/j.chroma.2009.11.068D.V.McCalley/J.Chromatogr.A1217(2010)858–8808591.IntroductionThe analysis of basic compounds by high performance liquid chromatography(HPLC)continues to be of interest,as over70% of pharmaceuticals are bases(with about20%being acids)[1–3].A large number of compounds of biomedical and biological signiﬁ-cance are also bases.Reversed-phase(RP)separations are by far the most common in liquid chromatography(LC),due to advantages that include ease of use with gradient elution,compatibility with aqueous samples,versatility of the retention mechanism allowing changes in the separation to be brought about by changes in pH, organic modiﬁer or additives,and long experience with the tech-nique,allowing the rapid establishment of suitable experimental conditions for the analysis of a given sample[4].Nevertheless,it has been recognised for a long time that the analysis of basic com-pounds poses particular difﬁculties in RP separations.Many of these problems are associated with the complex structure of the surface in silica-based RP packings,shown in Fig.1.The surface concentra-tion of silanols on bare silica is reported to be about8.0␮mol m−2 [5].C18ligands are too bulky to react completely with all silanols; thus,a maximum coverage of4–4.5␮mol m−2can be achieved.A further number of reactive silanols can be“endcapped”by reac-tion with smaller silylating agents such as trimethylchlorosilane, but as many as50%of the original silanol groups remain unreacted on a typical RP column.The average p K a of these silanol groups is around7.1,but their acidity can be enhanced by the presence of metal impurities in the silica.Some groups appear to be sufﬁ-ciently acidic that their ionisation cannot be entirely suppressed using acidic mobile phases with a pH within the stability limit of typical RP columns(2.5–7.5).Over this range of operational pH values,basic compounds are likely to be ionised,leading to ionic interactions with ionised silanol groups.BH++SiO−M+→SiO−BH++M+(1) where BH+represents the protonated base,and M+the mobile phase buffer cation.The problem of poor column efﬁciency(N)and exponentially tailing peaks shown by small quantities of bases is often attributed to this mixed mechanism process of hydropho-bic interaction and ion-exchange with the silanols.The slower sorption–desorption kinetics of silanol ion-exchange sites(kinetic tailing)with sample ions may be responsible[6],which will occur regardless of sample size.The simple existence of two retention processes cannot per se be the sole cause of tailing,as mixed-mode phases with carboxylic acid functions embedded within a hydrophobic chain can show excellent peak symmetry for bases[7]. However,the kinetics of interaction of such embedded groups,and the stereochemistry around the active site,could be completely dif-ferent from that of ionised silanols,which may be buried beneath the hydrophobic chains on classical C18phases.Instead of sim-ple ion-exchange sites,Neue et al.[8]have proposed the existence of strong synergistic sites with combined RP and ion-exchange properties.The overall retention for bases was described by the equation:k=k RP+k IX+k∗RP k∗IX(2) where k is the total retention,k RP is the hydrophobic contribu-tion,k IX is the ion-exchange contribution from surface silanols,and k∗RP k∗IX is a multiplicative contribution of both processes.These syn-ergistic sites could correspond to the subset of very high-energy sites with slow kinetics which have been long suspected to be the cause of exponential tailing for bases,as they appear to be domi-nant in the retention process.It was shown that this type of tailing is not responsive to small changes in sample load in RP–LC at low pH[6].This result might indicate that exponential tailing is not caused by overload of a small number of strong sites on the column. In contrast,overload often gives rise to right-angled triangle peak shapes when ionisation of silanols is suppressed in RP–LC when working at low pH.Overload tailing still occurs even for the most modern columns operated under conditions where there are no or a negligible number of ionised silanols on the column surface.It was recognised more than20years ago that bonded phases synthesised from pure silica(Type B phases)made from the hydrol-ysis of metal-free tetraalkoxysilanes resulted in reduced silanol acidity,and their use has considerably improved the analysis of bases[9].Only small contamination of such materials occurs dur-ing the processing of such packings,or from the water used in the hydrolysis.Nevertheless,some other features of the analysis of these solutes(such as overloading)remain problematic,and these issues have not been resolved by the use of high-purity silica.Already in1988,Snyder and co-workers[10]had reviewed the problems of analysis of basic solutes and had proposed some pos-sible solutions.The following recommendations were made: (a)Judicious selection of the column to reduce the number of avail-able acidic sites.(b)Reduction of the mobile phase pH to suppress ionisation of thesilanols.(c)Increasing the mobile phase pH above the analyte p K a,such thatthe analyte is unprotonated.(d)Addition of a silanol blocker such as triethylamine to the mobilephase to interact preferentially with ionised silanols.(e)Reduction of the sample concentration to alleviate the satura-tion of the acidic sites.Most of the arguments in this paper remain true more than20 years later,and these conclusions can be used as a simple guide for the chromatographer aiming to achieve the best separations for basic solutes.Perhaps only the use of silanol blocking agents has fallen somewhat out of favour,as these are less necessary with modern high-purity silica phases,and can also have some undesirable effects.Such effects include the generation of addi-tional background in HPLC–MS,the difﬁculty of removal from the stationary phase after use leading to permanent alteration of its properties,and even chemical reaction with some solute types.This topic,and some other well-known aspects of the chromatography of bases have been covered adequately in earlier reviews[11–13]. However,other features of the chromatography of these“difﬁcult”compounds are still extensively debated in the literature,for exam-ple,the problem of their ready overloading in RP separations.This review will concentrate on the latest research in these topics,while attempting to summarise brieﬂy previousﬁndings.Thus,it will con-sider RP column choice by use of evaluation data obtained from the Tanaka and the Snyder“hydrophobic subtraction”tests;current theories and the effect of overload for ionised solutes;the use of high pH to improve peak shape;whether temperature is a useful parameter in improving peak shape;andﬁnally whether other sep-aration mechanisms such as HILIC can provide a viable alternative to RP–LC for the analysis of bases.2.Choice of column2.1.Column testing proceduresThe selection of an appropriate RP column for the analysis of bases can be a daunting task,as now many hundreds are com-mercially available,with a considerable number recommended especially by their manufacturers for the analysis of basic solutes. Nevertheless,several databases are now available where a large number of different columns have been subjected to the same test procedure by the same group of workers on the same or similar instruments,allowing a useful and objective comparison of perfor-860 D.V.McCalley /J.Chromatogr.A 1217(2010)858–880Fig.1.Structures present on a typical RP monomeric-bonded silica (C8)endcapped with trimethylsilyl groups.After U.D.Neue,“Silica Gel and its derivatization for Liquid Chromatography”,in “Encyclopedia of Analytical Chemistry”,R.A.Meyers,Ed.,John Wiley &Sons,Ltd.,Chichester (2000)11450–11472.mance to be made.A question arises as to the validity of databases constructed by evaluation of only a few or even a single column of a given type,as to whether the results obtained may be truly repre-sentative of the performance of this brand,due to column to column and batch to batch variations.However,a careful study [14,15]has suggested that columns from major manufacturers actually show a rather high degree of reproducibility,probably resulting from the use of stringent quality control procedures.Indeed,the industry is likely to be self-regulating to a degree,as dissatisﬁed customers would switch to the use of more reproducible brands.Tight reten-tion speciﬁcations exist in the HPLC user environment,especially in the pharmaceutical industry,and changes in the column can jeop-ardise product release.However,it is possible that a manufacturer could be forced to change the sourcing of a production raw mate-rial,which might occur for example,if the column manufacturer does not make their own silica.Thus,under some circumstances,a recently purchased column may not behave in the same way as one tested several years beforehand.Nevertheless,we believe that such situations are rare,and in most cases,manufacturers strive to main-tain the reproducibility of their products over a long period of time,as many customers have established methods on a given brand of phase.It appears more common to introduce a new name or name variant of an existing phase to mark deﬁnitively such changes or improvements to the production process.Taking this factor,and the reasonable reproducibility of commercial columns into account,it seems that the results of tests on a particular brand of column would generally reﬂect the performance of that brand throughout the product lifetime.Both of the column evaluation methods described in detail below incorporate strongly basic compounds as test probes.In each test,their retention is monitored at low and intermediate pH val-ues.Columns which give relatively low retention of basic probes are also likely to give higher efﬁciency for basic solutes,as shown by correlation studies for at least one of the procedures (see below).2.2.The Tanaka test and the Snyder hydrophobic subtraction parison of results with direct peak shape measurementsWhile many different column testing methods have been devel-oped,two have become prominent and have the distinct advantage that databases of results for many hundreds,rather than just a few columns,are available.The Tanaka method [16]and the hydropho-bic subtraction procedure developed by Snyder et al.[17]both incorporate tests which allow a user to select phases that are likely to be suitable for the separation of basic compounds.We will consider here the Tanaka method as adapted and applied by Euerby and Petersson [18]to the evaluation of over 200commercial columns that can be compared on a freely available program from Advanced Chemistry Development [19].These databases appear to be updated periodically;for instance,the ACD database contains evaluations of recently introduced sub-2␮m phases.An alternative adaptation of the Tanaka procedure and its application to a large number of different stationary phases has also been made [20],and data are again freely available [21].A fourth testing scheme is that published by the US Pharmacopeia.This protocol is an adaptation of the work of Sander and Wise [22].For activity towards bases,this method uses the tailing factor of amitriptyline (the same probe as used in the Snyder–Dolan procedure).At the time of writing,the database contained fewer columns than the two major proce-dures (∼100)and will not be considered further here.However,data for both this procedure and the Snyder–Dolan (S–D)method are available on the USP website [23].In the Tanaka–Euerby (T–E)procedure,columns are tested by measurement of k for pentylbenzene as a measure of sur-face area and surface coverage;hydrophobic selectivity from the ratio of k (pentylbenzene)/k (butylbenzene);shape selectivity from k (triphenylene)/k (o-terphenyl);hydrogen bonding capac-ity from k (caffeine)/k (phenol)in unbuffered methanol–water;total ion-exchange capacity from k (benzylamine)/k (phenol in methanol–phosphate buffer pH 7.6;and acidic ion-exchange capacity from k (benzylamine)/k (phenol)in methanol–phosphate buffer pH 2.7.The latter three tests are of particular interest for the analysis of basic solutes.The program [19]allows the comparison of the similarities and differences between various columns,and per-mits the separate weighting of the various factors—for example,columns can be ranked according solely to their total ion capacity at pH 7.6if so desired.The S–D model recognises that hydrophobic retention is the dominant process in RP chromatography,and in the absence of other retention mechanisms,plots of log k for one column versus another should be a straight line.However,these other mechanisms give rise to scatter in the plots.Clearly,ion-exchange and hydrogen bonding are important contributors to the retention of basic solutes.The general equation for retention in theD.V.McCalley/J.Chromatogr.A1217(2010)858–880861Table1Evaluation of some selected RP columns by two different procedures.For details on the procedure,see text.Column name k pentylbz k(pentbz)/k(butbz)k(triphen)/k(terph)k(caff)/k(phen)k(bzm)/k(phen)2.7k(bzm)/k(phen)7.6Tanaka–Euerby procedureChromolith 4.22 1.24 1.310.480.120.63Discovery Amide 1.65 1.35 1.810.490.190.44Discovery C18 3.32 1.48 1.510.390.100.28Inertsil ODS-37.74 1.45 1.290.480.010.29Resolve C18 2.40 1.46 1.59 1.29 1.23 4.06Spherisorb ODS-2 3.00 1.51 1.560.590.230.76Symmetry C18 6.51 1.46 1.490.410.010.68Symmetry Shield RP18 4.66 1.41 2.220.270.040.20Xterra MS C18 3.52 1.42 1.260.420.100.35Xterra RP18 2.38 1.29 1.830.330.070.20H S A B C(2.8)C(7.0)Snyder procedureChromolith 1.0030.0290.008−0.0140.1030.187 Discovery Amide0.7200.013−0.6250.218−0.092−0.025 Discovery C180.9840.027−0.1280.0040.1760.153 Inertsil ODS-30.9900.022−0.146−0.023−0.474−0.334 Resolve C180.968−0.1270.335−0.046 1.921 2.144 Spherisorb ODS-20.962−0.0760.070.0340.908 1.263 Symmetry C18 1.0520.0630.018−0.021−0.3020.123 Symmetry Shield RP180.8500.027−0.4110.093−0.7280.136 Xterra MS C180.9840.012−0.143−0.0150.1330.051 Xterra RP180.757−0.043−0.4830.097−0.170−0.173model is:log˛=log k/log k(ethylbenzene)=Á Hhydrophobic − S∗steric resistance(to bulky interactions)+ˇ Acolumn H-bond acidity(non-ionised silanols)+˛ BH-bond basicity(from sorbed water)+Ä Cion interaction(ionised silanols)(3)Ethylbenzene is used as a non-polar reference solute.Greek letters represent empirical,eluent-and temperature-dependent proper-ties of the solute,which are relative to the values for ethylbenzene, for which all solute parameters are identically zero.The selection of the optimum probes for evaluation of each retention mode has been made from detailed studies.Bold capitals represent eluent-and temperature-independent properties of the column;these val-ues are relative to a hypothetical average Type B C18column.Any column which behaves identically to this hypothetical reference column will have H=1and all other values S*,A,B,C=0.The dataset of columns evaluated by this procedure is even larger than that for the T–E procedure and presently extends to at least400columns.In some versions of the program,different weightings can be assigned to each evaluation parameter,as in the Euerby procedure.Results for some RP columns selected from each database are shown in Table1.The T–E data show clearly that the older Type A bonded phases(Resolve C18and Spherisorb ODS-2)give higher retention of benzylamine relative to phenol at pH7.6(alpha values 4.06and0.76,respectively)compared with newer Type B phases based on highly pure silica(Discovery C18and Inertsil ODS-3, alpha values0.28and0.29,respectively).Similarly with the S–D method,values of C(7.0)for Resolve C18and Spherisorb ODS-2 are high(2.144and1.263,respectively)compared with Discov-ery C18and Inertsil ODS-3(0.153and−0.334,respectively.Values of alpha(benzylamine/phenol)at pH2.7and values of C(2.8)are also higher for the Type A compared with the Type B phases using both procedures,indicating general agreement between them. Snyder and co-workers[24]have correlated a published dataset of“silanol activity”for a number of RP columns(measured by the average plate number for amitriptyline and pyridine with methanol-phosphate buffer pH6.0)with values of C at pH6.0,inter-polated from C(2.8)and C(7.0).Columns with a highvalue of C(6.0) correlated with columns of high silanol activity,and those with low values of C(6.0)with low silanol activity.In a later study[6]95%of Type B columns(designated either on the basis of manufacturer claims,or on the date a column wasﬁrst sold)were shown to have C(2.8)≤0.25,while only11%of Type A columns satisﬁed this crite-rion.Tailing of basic solutes(as measured by the asymmetry factor A s)was minimal for columns with C(2.8)<0.25(i.e.Type B columns) and tended to increase for larger values of C(2.8).From Table1,the Type A phases Resolve C18and Spherisob-ODS-2,now identiﬁed as such due to values of C(2.8)≥0.25,also give the highest values of hydrogen bonding acidity(parameter A,0.335and0.07,respec-tively,determined from the retention of amide probe compounds). Similarly,these phases also gave the highest relative retention of caffeine/phenol in the Tanaka procedure(1.29and0.59,respec-tively).The data can also be used to compare the effect of other features,e.g.the performance of embedded polar group phases (EPG)and the equivalent conventional C18phase,manufactured on the same silica.EPG phases include columns with embedded amide groups within the hydrocarbon chain:or carbamate groups:EPG phases have been proposed to give better peak shapes for the analysis of bases[24,27].The incorporation of an EPG in XTerra RP18reduces somewhat the Tanaka alpha(benzylamine/phenol) 7.6parameter to0.20,compared with0.35for the XTerra MS C18 column.Similarly,the S–D C(7.0)parameter is reduced to−0.173 for the EPG compared with0.051for the conventional phase.It is862 D.V.McCalley /J.Chromatogr.A 1217(2010)858–880possible that the reduced retention of benzylamine and other bases may be caused by a layer of water that is adsorbed close to the surface of EPG phases,providing some deactivating effect for the silanol groups [25,26].Other authors have compared conventional and EPG phases bonded on the same type of silica,on the basis of peak shape measurements.It was found that on average,peak shapes were indeed improved on the latter phases [27].Neverthe-less,it appears that the EPG technology gives more improvement in performance with phases bonded on older impure silicas,rather than the modern Type B silicas [27].This result seems to be reﬂected in the somewhat inconclusive data from Table 1concerning the rel-ative retention of bases on conventional and EPG phases.Thus the Discovery EPG phase (amide)has a slightly larger value of the T–E alpha (benzylamine/phenol)7.6parameter (0.44)compared with the regular C18phase (0.28).In contrast,the S–D C (7.0)parameter is smaller on Discovery Amide (−0.025)compared with Discovery C18(0.153).Similarly,while the T–E procedure indicates a con-siderable lower value of alpha (benzylamine/phenol)at pH 7.6for Symmetry Shield (0.2)compared with Symmetry C18(0.68),the S–D C (7.0)parameter for the EPG phases is slightly greater (0.136)compared with the regular phase (0.123).Euerby and Petersson pointed out that the extra retentiveness of phenols on EPG phases might invalidate the results of tests for silanophilic activity which involve the use of such solutes.They therefore suggested substitut-ing benzyl alcohol for phenol in the Tanaka test.Benzyl alcohol has retention properties similar to those of phenol but does not show excess retention on EPG phases [28].These particular comparisons point to some possible differences in the compatibility of column evaluations from either method.The Hoogmartens group looked more generally at the compati-bility of results from the S–D method and their own adaptation of the Tanaka procedure [29],ﬁnding a rather poor overall correlation between the two approaches.In a previous paper,this group had demonstrated a good correlation between their own method and the Euerby results.This latter ﬁnding is perhaps not surprising,as both are based on the Tanaka method.The problem of compatibility of the S–D and Tanaka methods may well be in the different mobile phase conditions and different probe solutes used in these tests.The S–D procedure uses the retention of the strong bases amitriptyline and nortriptyline in acetonitrile–phosphate buffer to calculate the cation-exchange term C (2.8)and derives the value of C (7.0)from the C (2.8)results by multiplying by the ratio of the retention fac-tors of the quaternary amine berberine at pH 7.0and 2.8;the T–E benzylamine tests use methanol as the organic modiﬁer.Indeed the use of these different modiﬁers may explain the somewhat differ-ent evaluations of the EPG phases by either method.Even using the same mobile phase conditions,McCalley and Brereton [27,30–32]showed that peak shape data was not consistent between different basic probes.Thus,for example there was little correlation between A s for codeine and nortriptyline when using methanol–phosphate buffers at pH 3.0,whereas either of these solutes has been used as a single test compound to evaluate the relative silanol activity of different phases.One phase (Waters Symmetry Shield)gave,of 9highly inert RP columns,the highest N and lowest A s for nico-tine using acetonitrile–phosphate buffer at pH 7.0but the lowest efﬁciency for analysis of pyridine.Fig.2shows a principal compo-nents analysis (PCA)loadings plot for analysis of nine basic solutes on eight different RP columns using a mixture of methanol with a pH 3.0buffer.Lines can be drawn from the centre of the plot to each data point.Parameters that are opposed (i.e.appear at 180◦)measure equivalent but opposite trends.Thus N and A s values are opposed,with efﬁciency increasing as asymmetry decreases,as expected.Parameters that are at 90◦,like the asymmetry factors of pyridine and quinine,measure unrelated trends,and thus may be evaluating relatively different aspects of the detrimental inter-action of bases with the column surface.Conversely,the asymmetry parameters of nortriptyline and diphenhydramine have a smaller angle between them,and may be measuring more related proper-ties.It might therefore not be necessary to include both substances in a test mix for these particular mobile phase conditions.For over-all evaluation of column properties exploring different aspects of detrimental interactions,a test mix could include ﬁve compounds:codeine,quinine,amphetamine,nortriptyline and pyridine.The ranking of columns at pH 7using methanol was different from that at pH 7using acetonitrile;note that these correspond to the differ-ent modiﬁers of the T–E and S–D evaluation schemes,respectively.Snyder and co-workers [6]also observed that the tailing of basic (cationic)solutes on a given column appeared to be solute speciﬁc,ﬁnding that values of A s for the bases amitriptyline,nortriptyline,the quaternary compound berberine,and 4-n -hexylaniline corre-lated extremely poorly (r 2=0.01–0.19).The use of multiple basic test solutes and different mobile phase modiﬁers at different pH values would be a considerable task for the construction of these column evaluation databases.However,inclusion of a range of test compounds would undoubtedly improve the performance of these databases.It seems certain that these differences in test solutes and conditions contribute to the lack of correlation between the S–D and T–Etests.Fig.2.PCA loadings plots based on retention factor (k ),column efﬁciency (N ),Dorsey–Foley column efﬁciency (N df )and asymmetry factor (A s ).Data for eight different Type B reversed-phase columns and nine different probe compounds with methanol–phosphate buffer pH 3.0as mobile phase.See [30].。

不同外加剂对氧化镁水化的影响

中图法分类号：ＴＱ１７４．７５
文献标识码：Ａ
文章编号：１０００—２２７８（２０１８）０１—００８２—０４
ＥｆｆｅｃｔｏｆＤｉｆｆｅｒｅｎｔＡｄｄｉｔｉｖｅｓｏｎｔｈｅＨｙｄｒａｔｉｏｎｏｆＭｇＯＰｏｗｄｅｒｓ
ＺＨＡＮＧＹａｎｇｆａｎ，ＤＵＡＮｈｏｎｇｊｕａｎ，ＺＨＡＮＧＨａｉｊｕｎ，ＴＩＡＮｌｉａｎｇ（ＴｈｅＳｔａｔｅＫｅｙＬａｂｏｒａｔｏｒｙｏｆＲｅｆｒａｃｔｏｒｉｅｓａｎｄＭｅｔａｌｌｕｒｇｙ，ＷｕｈａｎＵｎｉｖｅｒｓｉｔｙｏｆＳｃｉｅｎｃｅａｎｄＴｅｃｈｎｏｌｏｇｙ，
厅高等学校优秀中青年科技刨新团队计￣（Ｔ２０１６０２）；湖北省教育
厅科学研究计划指导性项目（Ｂ２０１６００１）。
通信联系人：段红娟（１９８０一），女，副教授。
Ｒｅｃｅｉｖｅｄｄａｔｅ：２０１７—０３—１２．Ｒｅｖｉｓｅｄｄａｔｅ：２０１７—０５—１０．Ｃｏｒｒｅｓｐｏｎｄｅｎｔａｕｔｈｏｒ：ＤＵＡＮＨｏ￣ｕａｎ（１９８０－），缸咄Ａｓｓｏｄａｔｅｐｒｏｆｅｓｓｏｒ
第３９卷第１期２０１８年２月
ＤＯＩ：１０．１３９５７￣．ｃｎｋｉ．ｔｃｘｂ．２０１８．０１．０１７
瓷李旅
ＪｏｕｒｎａｌｏｆＣｅｒａｍｉｃｓ
Ｖ０１．３９Ｎ０．１Ｆｅｂ．２０１８
不同９ｂ￣Ｊｎ剂对氧化镁水化的影响
郑扬帆，段红娟，张海军，田亮
（武汉科技大学省部共建耐火材料与冶金国家重点实验室，湖北武汉４３００８１）
国内外的研究人员通过选择不同的外加剂，改变外加剂的用量，调节反应温度等手段控制氧化镁的水化，以改善含氧化镁浇注料的流动性和凝结时间，从而有助于提高浇注料的施工性能。李陇岗等

海藻酸盐凝胶抗冻性研究

Hans Journal of Food and Nutrition Science 食品与营养科学, 2021, 10(2), 87-92Published Online May 2021 in Hans. /journal/hjfnshttps:///10.12677/hjfns.2021.102012海藻酸盐凝胶抗冻性研究邢晓亮1,2，逄圣慧1,2*，范素琴1,2，张美迪1,2，王斌1,2，逄锦龙1,2，丁玉龙1,2，申培丽1,21青岛明月海藻集团有限公司海藻活性物质国家重点实验室，山东青岛2青岛海藻生物科技创新中心，山东青岛收稿日期：2021年3月18日；录用日期：2021年5月12日；发布日期：2021年5月19日摘要目的：为提高海藻酸盐凝胶抗冻性能。

方法：本实验采用罗望子胶、黄原胶、海藻糖、大豆蛋白、变性淀粉制作海藻酸钠凝胶。

结果表明采用大豆蛋白、变性淀粉制作的海藻酸钠凝胶，在−18℃下冷冻4小时后解冻，解冻后凝胶质地仍较好，保水较好。

本研究为冷冻海藻酸钠凝胶性能提升的可能性提供了数据支撑，为冷冻海藻酸钠产品的生产提供了理论参考。

关键词海藻酸钠，凝胶，冷冻，质构，保水性Study on Freezing Resistance of Alginate GelXiaoliang Xing1,2, Shenghui Pang1,2*, Suqin Fan1,2, Meidi Zhang1,2, Bin Wang1,2, Jinlong Pang1,2, Yulong Ding1,2, Peili Shen1,21State Key Laboratory of Bioactive Seaweed Subtances, Qingdao Brightmoon Seaweed Group Co., Ltd.,Qingdao Shandong2Qingdao Seaweed Biotechnology Innovation Center, Qingdao ShandongReceived: Mar. 18th, 2021; accepted: May 12th, 2021; published: May 19th, 2021AbstractPurpose: To improve the antifreeze performance of alginate gel. Methods: The alginate gel was prepared by Tamarind polysaccharide gum, Xanthan gum, Seaweed sugar, Soybean protein and modified starch. The results showed that the alginate gel made from soybean protein and mod-ified starch was frozen a t −18˚C for 4 hours and thawed. After thawing, the gel quality remained good and water retention was good. This study provides data support for the possibility of im-*通讯作者。

不同防腐剂对抹茶拿铁饮料保鲜影响的研究

特产研究75Special Wild Economic Animal and Plant ResearchDOI：10.16720/ki.tcyj.2023.149不同防腐剂对抹茶拿铁饮料保鲜影响的研究何文毅，邢威，王晨，崔叶，汪艳霞※（贵州大学茶学院，贵州贵阳550000）摘要：抹茶拿铁饮料是由抹茶粉与牛奶等成分调配而成的饮品，具有抹茶和牛奶中的营养成分。

因其饮用方便、营养丰富、风味优良等特点在国内外市场上广受青睐。

为更好的延长抹茶拿铁饮料的货架期，本研究以抹茶拿铁粉末冲泡后的饮料为研究对象，按照国家标准GB/2760—2014《食品添加剂》中的规定，考察了溶菌酶、二甲基二碳酸盐（Dimethyl dicarbonate,DMDC）、乳酸链球菌素、-聚赖氨酸盐酸盐、山梨酸钾对抹茶拿铁饮料抑菌效果和品质的影响，筛选出最佳杀菌防腐剂为二甲基二碳酸盐（DMDC）。

研究了DMDC 杀菌后抹茶拿铁饮料于4℃冷藏环境条件下储藏30d期间，微生物的生长变化规律和品质的影响。

结果表明，DMDC处理对抹茶拿铁饮料具有显著的杀菌作用，有效抑制了细菌、霉菌、酵母菌等微生物在储藏过程中的生长繁殖。

相较于热杀菌，DMDC处理对抹茶拿铁饮料的风味和口感几乎没有影响。

此外，抹茶拿铁饮料经过DMDC杀菌后的颜色变化相对较小。

因此，DMDC处理可以有效延长抹茶拿铁饮料的冷藏期，并能更好地保持抹茶拿铁饮料的品质。

关键词：抹茶拿铁饮料；不同防腐剂；二甲基二碳酸盐（DMDC）；杀菌效果；保鲜中图分类号：TS272.4文献标识码：A文章编号：1001-4721（2023）05-0075-07Effect of Different Preservatives on the Preservation of Matcha Latte BeverageHE Wenyi,XING Wei,WANG Chen,CUI Ye,WANG Yanxia※(Tea College of Guizhou University,Guiyang550000,China)Abstract:Matcha latte beverage is a beverage made by blending Matcha powder with milk and other ingredients.It contains trace elements and nutrients found in Matcha and milk,and is widely favored in domestic and international markets due to its convenient drinking,rich nu-trition,and excellent flavor.To better extend the shelf life of Matcha latte beverages,in this study,the beverage brewed with matcha latte powder was taken as the research object.According to the provisions of the national standard GB/2760—2014food additives,the effects of lysozyme,dimethyl dicarbonate(dimethyl dicarbonate，DMDC),Lactococcin-polylysine hydrochloride and potassium sorbate on the anti-bacterial effect and quality of Matcha latte beverages were studied.The optimal bactericidal and preservative,DMDC was selected.The gro-wth and changes of microorganisms during the30day storage period of Matcha latte beverages under4℃cold storage environment after DMDC sterilization were studied.The results showed that DMDC treatment had a significant bactericidal effect on Matcha latte beverages, effectively inhibiting the growth and reproduction of microorganisms such as bacteria,molds,and yeast during pared to thermal sterilization,DMDC treatment has almost no effect on the flavor and taste of Matcha latte beverages.In addition,the color change of Matcha latte beverage after DMDC sterilization is relatively small.Overall,DMDC treatment can effectively prolong the refrigeration period of Matcha latte beverages and better maintain the quality of Matcha latte beverages.Key words:matcha latte beverage;different preservatives;dimethyl dicarbonate(DMDC);sterilization effect;preservation在《抹茶》国家标准GB/T34778—2017中，抹茶被定义为：“抹茶，采用覆盖遮阴栽培的茶树鲜叶，经蒸汽或热风杀青、干燥加工的叶片为原料，再经研磨工艺加工而成的微粉状茶产品”[1]。

茶多酚-壳聚糖活性保鲜膜的制备及其稳定性研究

文章编号：1673-887X(2023)05-0093-04茶多酚-壳聚糖活性保鲜膜的制备及其稳定性研究刘佳禾，王晨曦，张晟宝，郭瑶，李彦仪，姚沁含，蒋企洲（中国药科大学，江苏南京210000）摘要探究制备壳聚糖膜的成分比例以及工艺流程，确保成品膜物理性能达标。

2%的乙酸、0.5%甘油以及40℃的成膜条件能制备物理性能较优的壳聚糖膜。

茶多酚浓度的大小决定膜的还原性、抑菌性，壳聚糖与柠檬酸对其性质不作影响。

本课题设计的成品具有较优的物理性质与抑菌性，同时具有可降解性、无抗原性、易得性等，对制备环保抑菌的保鲜膜具有一定意义。

关键词茶多酚；壳聚糖膜；可降解；抗氧化；抑菌中图分类号F316.5文献标志码A doi:10.3969/j.issn.1673-887X.2023.05.035Preparation and Stability of Tea Polyphenol Chitosan Active Preservative FilmLiu Jiahe,Wang Chenxi,Zhang Shengbao,Guo Yao,Li Yanyi,Yao Qinhan,Jiang Qizhou(China Pharmaceutical University,Nanjing210000,Jiangsu,China)Abstract：The composition ratio and technological process of preparing chitosan film were explored to ensure the physical proper‐ties of finished film meet the standards.Chitosan films with better physical properties were prepared by2%acetic acid,0.5%glycer‐in and40℃.The reducing and bacteriostatic properties of tea polyphenols were determined by the concentration of tea polyphenols, but chitosan and citric acid did not affect the properties.The finished product designed in this subject has better physical properties and bacteriostasis,as well as degradability,no antigenicity,accessibility,etc.,which has a certain significance for the preparation of environmental protection and bacteriostasis plastic wrap.Key words：tea polyphenols,chitosan membrane,degradable,antioxidation,bacteriostasis随着能源危机和“白色污染”等环境问题日益严峻，保鲜膜作为日常生活中使用较多的塑料制品，市场需求极大。

工厂化条件下外源添加剂对猪粪堆肥过程中NH3和H2S的减排效果

宋修超，郭德杰，成卫民，等.工厂化条件下外源添加剂对猪粪堆肥过程中NH 3和H 2S 的减排效果[J].农业环境科学学报,2021,40（9）：2014-2020.SONG X C,GUO D J,CHENG W M,et al.Pilot-scale study on effects of exogenous additives on reducing NH 3and H 2S emissions from pig manure compost[J].Journal of Agro-Environment Science ,2021,40（9）：2014-2020.开放科学OSID工厂化条件下外源添加剂对猪粪堆肥过程中NH 3和H 2S 的减排效果宋修超1，郭德杰1，成卫民3，罗佳1，徐烨红1，王光飞1，刘新红1，马艳1，2*（1.江苏省农业科学院农业资源与环境研究所，农业农村部长江下游平原农业环境重点实验室，南京210014；2.江苏大学环境与安全工程学院，江苏镇江212013；3.农业农村部环境保护科研监测所，天津300191）Pilot-scale study on effects of exogenous additives on reducing NH 3and H 2S emissions from pig manurecompostSONG Xiuchao 1,GUO Dejie 1,CHENG Weimin 3,LUO Jia 1,XU Yehong 1,WANG Guangfei 1,LIU Xinhong 1,MA Yan 1,2*（1.Institute of Agricultural Resources and Environment,Key Laboratory of Agro-Environment in Downstream of Yangtze Plain,Ministry ofAgriculture and Rural Affairs,Jiangsu Academy of Agricultural Sciences,Nanjing 210014,China;2.School of Environmental and Safety Engineering,Jiangsu University,Zhenjiang 212013,China;3.Agro-Environmental Protection Institute,Ministry of Agriculture and Rural Affairs,Tianjin 300191,China ）Abstract ：This study aims to determine how nitrogen and sulfur are transformed into NH 3and H 2S while pig manure is composted with different additives under factory conditions,and to understand the effect of reducing NH 3and H 2S emissions on composting.Fourtreatments,in which zeolite （10%）and superphosphate （5%）were added to the manure separately,another in which both were added,and a final treatment without additives that was used as the control （CK ）,were set up in a pilot study.The results showed that different additives收稿日期：2021-02-25录用日期：2021-05-19作者简介：宋修超（1987—），男，山东即墨人，博士，助理研究员，研究方向为农业废弃物肥料化利用。

食品添加剂对烘焙月饼保质期的影响

1 材料与方法
1.1 仪器设备电子天平、粉碎机或捣碎机、索氏脂肪抽提器、
抽真空设备、气调包装设备、烤箱、恒温箱、恒温水浴锅、旋转蒸发仪、鼓风干燥箱、锥形瓶、移液管、滴定管、量筒、容量瓶。 1.2 试剂材料
乙醚 - 乙醇（2+1）混合液、1% 酚酞指示液、 0.1 mol·L-1 氢氧化钾标准溶液、饱和碘化钾溶液、三氯甲烷 - 冰乙酸（2+3）混和液、0.002 mol·L-1 硫代硫酸钠标准溶液、1% 淀粉溶液、小麦面粉、鸭蛋黄、红豆沙馅、白糖浆、碱水、生油、鸡蛋、蜂蜜、丙酸钙、山梨酸钾、脱氢醋酸钠。
工艺技术 Process Technology
doi:10.16736/41-1434/ts.2020.19.029
食品添加剂对烘焙月饼保质期的影响
The Effect of Food Additives on the Shelf Life of Baked Moon Cakes
◎ 刘丽婉（汕头检验检测学会，广东汕头 515041）
随着我国对传统中秋文化的重视，烘焙月饼在人们的生活中占据了越来越重要的位置。但烘焙月饼的保质期或货架期一直备受争议：月饼属于季节性产品，消费期较短，且月饼属于高糖、高油，在生产、储存、运输、销售等过程中，易受周围环境中微生物的污染，从而引起月饼发硬、发霉、哈败等问题。 [1-2] 因此，对烘焙月饼保质期质量把控的研究具有重要的意义。
Liu Liwan (Shantou Institute of Testing and Inspection, Shantou 515041, China)
摘要：通过与对照组的单因素实验，研究山梨酸钾、丙酸钙、脱氢醋酸钠对月饼保质期的影响。结果显示：食品添加剂山梨酸钾、丙酸钙、脱氢乙酸钠均可延长月饼的保质期，其中山梨酸钾可延长 32 ～ 58 d 保质期，丙酸钙可延长 33 ～ 66 d 保质期，脱氢醋酸钠可延长 28 ～ 53 d 保质期；按保质期大小排序为：丙酸钙＞山梨酸钾＞脱氢醋酸钠；以综合平衡法分析，月饼最优烘焙工艺为 A3B3C2，即混和物料温度为 70 ℃，烘焙温度为 240 ℃，烘焙时间为 20 min。

不同茶叶及添加量对皮蛋品质的影响

Effect of Different Types of Teas and Additives on the Quality of Preserved Egg
作者：刘金仙;刘金明;陈红;岑家鋆
作者机构：武夷学院茶与食品学院,福建武夷山354300
出版物刊名：宜春学院学报
页码： 77-80页
年卷期： 2016年第9期
主题词：茶叶皮蛋外观品质口感风味总碱度
摘要：目的：研究腌制料液中茶叶种类及其添加量对皮蛋品质的影响,为茶叶在皮蛋加工中的标准化添加提供参考依据。

方法：采用浸泡腌制法腌制皮蛋,通过对皮蛋的感官评价及总碱度测定,确定用于皮蛋腌制的最佳茶叶种类及最佳添加量。

结果：用添加量为5%的红茶所腌制皮蛋外观品质好,口感风味好,总碱度符合国标要求,综合品质最佳。

结论：皮蛋加工建议选用红茶,添加量为5%为宜。

2020-2021学年仁爱版英语七年级下册词汇讲义拓展学习法(第248组)

词汇讲义拓展学习法第248组shorts1) shorts [英][ʃɔ:ts] [美][ʃɔrts]球裤1.a pair of cricket flannels一条男用法兰绒板球裤.2.Football players wear shorts.足球运动员穿短裤。

3.Bob's team has blue T-shirts and blue shorts.“鲍勃的球队穿蓝色体恤衫和蓝色短裤。

”4.The other team has orange shorts and T-shirts.“另外一支球队穿橙色的短裤和体恤衫。

”5.I always wear a T-shirt, shorts and runners to play basketball.我经常穿T恤衫，短裤和跑鞋打篮球。

6.So I wore my tennis shorts, a T-shirt, and sneakers.所以我穿了我的网球短裤，T恤衫和运动鞋。

7.He laid off his sweat suit on a bench and went into the shower room. 他把球衫裤往长凳上一放就到淋浴室去了。

词汇讲义拓展学习法8.He developed a list of rules and formed the first baseball team, the New York Knickerbockers.他制定了棒球规则并且成立了第一支棒球队??纽约灯笼裤队。

9.If you are going to enter a formal golf course, can you dre yourself with a T-shirt without collar and short pants?进入正式的高尔夫球场，适宜穿无领T 恤和短裤吗？10.I'd say a witty T-shirt, shorts and tennis shoes should be about right.穿一件帅气的T恤衫，一条运动短裤和一双网球鞋就够了。

导电剂对锂离子电池性能的影响[1]

对碳黑和碳丝分别用丙酮二氯甲烷和聚丙二醇进行了处理发现在容量电极的电解液吸附量吸附7率电阻和电极密度等方面经过处理的样品包括碳黑和碳丝在各方面都占优势对其进行循环伏安测试得到的曲线图更具对称性和稳定性这也就提高了以其为导电剂的电池的循环稳定性
导电剂对锂离子电池性能的影响/ 刘
露等
267 本页已使用福昕阅读器进行编辑。福昕软件（Ｃ）２００５－２０１０，版权所有，仅供试用。
Abstract
T he effect of differ ent conductiv e ag ents on cycle behav ior o f lithium io n batteries is rev iewed. T he
pr operties o f lithium ion bat teries can be o bv iously impr oved by using carbon black as the conductiv e mater ial, and it will be better if using carbo n filament. L arg e capacity and high cy cle eff iciency can be kept at high char ge rate by adding high electr ical co nductivit y metal. T he content of conductiv e additive also has an influence on the cy cle perfo rmance. T he excessive content of conductiv e mater ial w ill lead to low capacity because of small act ive material, on the contra ry, the less co ntent will br ing the bad conductiv ity and po lar izat ion. T he size and disper sion have a signif icant effect o n the batt er ies. In addition, so me surace modificat ion impro ve t he cycle per for mance o f lithium ion batt er ies befo re commixing .

氮化硅流延膜的制备_陈殿营

氮化硅流延膜的制备陈殿营　张宝林　庄汉锐　李文兰(中国科学院上海硅酸盐研究所,上海　200050) 摘　要　流延成型是一种制备高质量陶瓷基片的成型方法。

氮化硅是一种高热导率的材料,有望在电子基片领域获得应用。

本文利用流延成型制备了具有较好柔韧性和一定强度的氮化硅流延素坯膜。

研究了无水乙醇、无水乙醇/丁酮作为溶剂时对浆料粘度的影响。

通过优化流延浆料添加剂的各种配比,得出了适合氮化硅粉体(SN -E10)流延的最佳配方。

关键词　流延成型　氮化硅　基片中科院创新基金资助项目.作者简介:陈殿营(1975～),男,硕士.主要从事氮化硅粉末晶析的研究. 随着电子元件的小型化及大规模集成电路的迅速发展,对作为集成电路重要支柱的陶瓷基片提出了更高的要求。

在某些特殊的领域,不但要求该陶瓷基片具有良好的导热性能,而且具有更高的强度。

目前广泛采用的陶瓷基片材料主要是Al 2O 3,但Al 2O 3基片具有热导率较低、介电常数大、线胀系数与硅元件的线胀系数相差大等缺点,近年来正开发和研究代替氧化铝基片的其它材料,如AlN ,BeO ,SiC ,Si 3N 4等。

其中氮化硅陶瓷基片不但具有高的热导率[1～10](文献报道最高值162W /m ·K ),而且具有更高的强度。

因此,对氮化硅陶瓷基片的研制,将会给电子技术领域,尤其是集成电路的发展带来革命性的影响。

陶瓷基片制备的核心技术是高质量基片坯体的成型,目前的成型方法主要有流延、干压、轧膜,而流延法具有生产效率高,易于生产的连续化和自动性,更适用于工业的大规模生产[11]。

流延成型工艺的基本过程是把粉料、溶剂、增塑剂、粘结剂、分散剂均匀混合成浆料,经由刮刀口,形成表面光滑,厚度均匀的薄膜,经干燥制成具有良好韧性的坯片。

本文通过优化流延浆料添加剂的各种配比,得出了适合流延成型的浆料的最佳配方,并制备出了具有较好柔韧性和一定强度的氮化硅流延素坯膜。

1　实验方法本实验选用α-Si 3N 4(SN -E10)为原料,从流延成型的角度出发,分别选用了无水乙醇(EtOH )和丁酮(ME K )的二元恒沸混合物做溶剂,磷酸三乙酯(TEP )做分散剂,聚乙烯醇缩丁醛(PVB )做粘结剂,聚乙二醇(PE G )和邻苯二甲酸二乙酯(PHT )做增塑剂。

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