复合酶法提取褐藻酸钠的工艺研究

用复合酶法提取海带中的褐藻酸钠,并对工艺进行优化。通过对单因素实验和正交试验结果的分析,确定褐藻酸钠最佳提取工艺为:粉碎的海带经过浸泡过滤后,加入海带干重1%(m/m)的纤维素酶和1%(m/m)的果胶酶,55℃(p H值4.5)水解2h,再加入1%(m/m)的木瓜蛋白酶,85℃(p H值8.5)水解2 h。此工艺的提取率高,产品纯度高,是对海带多糖传统提纯工艺的革新。     

酸解法对甘氨酸母液脱色后废活性炭的再生研究

在用海因法生产甘氨酸的过程中,为了精制甘氨酸,需要用大量的活性炭对甘氨酸母液进行脱色,而脱色后的活性炭就成了废活性炭.为了实现废活性炭的再利用,针对此废活性炭用酸解法对其进行再生.研究了再生酸种类、浓度、用量、再生温度和再生时间等对废活性炭再生效果的影响,确定了适宜的再生条件:硫酸质量分数为70％,硫酸溶液与废活性炭的...     

雪灵芝水溶性多糖提取工艺优化及其数学模型的建立

目的 优化雪灵芝水溶性多糖的提取工艺,并建立数学模型.方法 采用水提醇沉法提取雪灵芝水溶性多糖;运用苯酚-硫酸法测定多糖含量;通过单因素实验研究浸提时间、加水比、浸提温度及乙醇浓度对多糖提取率的影响;采用响应面分析法优化提取条件,运用sas软件分析实验数据,建立回归模型.结果 得到雪灵芝水溶性多糖提取的优化工艺参数的最佳取值范围为:浸提温度(94.5～97.5℃);浸提时间(2～2.5h);加水比(43～51v/w).结论 为雪灵芝水溶性多糖提取工艺的优化提供了一定的技术依据,也为其后续研究奠定了基础.     

热固性树脂基复合材料的变革性制造方法研究进展

热固性树脂所特有的共价键交联网络结构,使其及其复合材料的降解回收再利用、连接、损伤修复、3D打印等成为世界难题,也对学术界和工业界提出了重大挑战.人们为此付出了巨大的努力,但并未取得预期效果.最近出现的自适应热固性树脂,为解决这些难题提供了新的机会.本课题组针对典型的自适应热固性树脂,构建了跨尺度热压辅助连接界面力学模型及有限元实现方法,研究了小分子介入的酯键交换反应原理,实现了自适应热固性树脂的无压力连接,连接界面的断裂能可达4000 J/m2,实现了自适应热固性树脂的循环3D打印,自适应热固性树脂基复合材料的损伤修复、基体和纤维的近乎100%的回收再利用,实现了工业用环氧树脂基复合材料中碳纤维和玻璃纤维的回收.这些方法有希望成为热固性树脂基复合材料的变革性制造技术.本文拟综述这方面的最新研究进展,并指出存在的问题和挑战,提出理论研究、材料设计、工业应用等未来发展方向.     

次氯酸钠与二氧化氯在给水消毒中的应用进展

归纳了次氯酸钠和二氧化氯在给水消毒中的应用进展,比较了二者作为液氯替代消毒剂的消毒效能、安全性、发生工艺、应用成本,指出二氧化氯在消毒效果、副产物安全性、杀藻除味等方面优于次氯酸钠,开发与推广"氯酸钠高纯法"二氧化氯发生工艺是未来的发展方向。     

微生物多糖的应用研究进展

微生物多糖以其安全、无毒、理化性质独特等优良特性,被广泛地应用于工业生产中,具有较强的市场竞争力和广阔的发展前景.本文主要介绍了微生物多糖的来源及其在食品、医药、环境等方面的应用.     

基于预测滤波器的故障诊断方法研究

提出了基于预测滤波器的非线性系统的系统故障诊断的方法, 并且给出了这种方法的故障可检测性条件, 故障的误检率和漏检率, 以及故障检测时间的上界. 通过对一个二阶非线性系统进行的仿真验证了这种方法的有效性. 结果表明预测滤波器用于故障诊断时, 具有较快的速度、较低的误检和漏检率, 并且在故障发生后仍然具有对系统状态的跟踪能力. 该方法提供的实时故障估计还可以用于在线故障补偿.     

固体火箭发动机喷管烧蚀控制机制判别新方法

合理的固体火箭发动机喷管烧蚀控制机制判别方法能提高烧蚀率计算的精度.基于H2O和CO2与C反应具有不同的化学反应常数,综合考虑了壁面温度和燃气氧化组分浓度对烧蚀率的影响,提出了一种判别烧蚀控制机制的新方法.应用该判别方法对喷管喉忖烧蚀问题进行了数值模拟.计算结果表明,本文采用的计算方法得到的烧蚀率小于按扩散速率控制和双控制计算得到的烧蚀率,且与试验结果更接近.同时指出燃气中由H2O引起的烧蚀率是导致喷管喉忖烧蚀的主要原因.     

基于光学原位观测柔软摩擦副的接触率研究

＂柔软接触＂在自然界和工业应用的摩擦副中具有重要学术和应用价值,但线接触副中接触率的原位测量目前尚无系统方法.本文建立了含光学显微、数字图像采集的软摩擦试验台.通过对接触率不同影响因素的深入分析,对比讨论了试验结果和理论模型.法向载荷对接触率影响规律可表述为幂函数,且受到弹性模量的影响.本文结合Ghatak的柔软橡胶薄层力学模型,分析了柔软材料的弹性模量对接触率的具体影响规律.本文以上述分析为基础,针对实际应用中柔软材料几何尺寸差异的问题,制备了9种不同厚度的圆柱形弹性样品,试验和理论分析都发现临界厚度值将影响接触率,并对结果进行了讨论.最后对全文进行了总结和展望.     

基于句法分析的评价搭配抽取及其倾向性分析

提出一种新的基于句法分析的方法可以提取出评价搭配.通过对大量的商品评论进行句法分析,得到了常用的评论模式集合.依靠这些模式对评价搭配进行抽取.同时,构建了一种映射集合,可以映射出隐式评价对象.对于评价对象的倾向性判别,通过hownet构建了情感种子词典,采用SO-PMI方法计算出其极性,并计算出极性强度.实验结果表明,该方法对于评价搭配的抽取和极性分析具有较好的精确率和召回率.     

A technique for sterile culture of fresh water sponges

Summary By treating the gemmules of freshwater sponges successively with hydrogen peroxide and with sodium hypochlorite in suitable concentrations, we obtained cultures that were free from any bacterial or fungal contaminant. This technique provides a useful tool for further studies on metabolic and antibiotic activities, and of the behaviour of isolated cells cultivated in artificial media.F.R. is grateful to NATO, for a grant which allowed her to stay at the Department of Cell Biology of the University of Glasgow and to all the members of this laboratory for their help.     

海藻酸钠及其复合材料在生物医药中的研究进展

海藻酸钠具有良好的生物相容性和吸湿性能,其复合材料具有优异的力学性能和降解可控性能,可以作为药物的载体材料和组织工程中的支架材料。本文综述了海藻酸钠及其复合材料在缓控释制剂中、组织工程中以及医用敷料中的研究进展。     

苯酚在氨氮体系中的氧化降解研究

研究了氨氮存在下次氯酸钠处理苯酚模拟废水的氧化特性,探讨了苯酚在氨氯体系中的反应途径。实验结果表明:在含氨氮的苯酚废水中加入次氯酸钠,氨氮将与苯酚发生竞争反应。折点加氯曲线表现为当氯与氨氮质量比由5.35上升到27.67时,氨氮去除率的变化趋势滞后;而余氯量则不断减小,没有折点出现。随着氨氮浓度增加,苯酚的氧化降解受到抑制:一方面,苯酚的去除率不断下降;另一方面,体系中检测到一系列氯酚中间产物,其生成量和种类先增加后减少。HPLC分析结果显示体系中生成的氯酚中间产物至少有2种(2-氯酚和4-氯酚),至多有5种(2-氯酚、4-氯酚、2,6-二氯酚、2,4-二氯酚和2,4,6-三氯酚)。其中,2-氯酚和4-氯酚是导致三卤甲烷产生的最有效前体物质,而2,6-二氯酚、2,4-二氯酚和2,4,6-三氯酚则是生成卤乙酸的高活性物质。实验结果对次氯酸钠处理含氨氮的难生化或有毒有机废水具有一定的参考价值。     

Model systems demonstrating the volatile mutagenicity and carcinogenicity of sodium nitrite in rats

Volatile mutagens derived from sodium nitrite buffered at various pH values or in the presence of human feces were detected using Ames Salmonella tester strain TA 1535 on petrie plates inverted over samples. Volatile mutagenicity increased as the pH decreased and was primarily a function of the nitrous acid produced from sodium nitrite and hydrogen ions. Sodium nitrite administered intracecally to 3 Wistar rats through surgically implanted cannula caused tumors (fibrosarcoma: 1/3 and squamous cell, 2/3). The possible role of nitrite-derived mutagens in GI cancer is discussed.     

The autoxidation of glyceraldehyde and other simple monosaccharides

Summary Simple monosaccharides are shown to autoxidize, under physiological conditions, forming dicarbonyl compounds and hydrogen peroxide via reactive intermediates of dioxygen and carbon centred free radicals. The rate of enolisation of the substrate to form an enediol is the rate limiting step of this spontaneous process.Acknowledgments. We should like to thank the NIH, MRC ICI Pharmaceuticals Ltd and the SERC for financial support; Dr D. Earle for helpful conversations, Mr. A.J. Bron for provision of laboratory facilities and Dr. J.V. Bannister for the generous gift of superoxide dismutase.     

Model systems demonstrating the volatile mutagenicity and carcinogenicity of sodium nitrite in rats

Summary Volatile mutagens derived from sodium nitrite buffered at various pH values or in the presence of human feces were detected using AmesSalmonella tester strain TA 1535 on petrie plates inverted over samples. Volatile mutagenicity increased as the pH decreased and was primarily a function of the nitrous acid produced from sodium nitrite and hydrogen ions. Sodium nitrite administered intracecally to 3 Wistar rats through surgically implanted cannula caused tumors (fibrosarcoma: 1/3 and squamous cell, 2/3). The possible role of nitrite-derived mutagens in GI cancer is discussed.The authors are grateful to Dr A. Carl MacDonald of the Dept. of Surgery, Dalhousie University for his advice and encouragement in this project.This work was supported by the National Cancer Institute of Canada.     

A study of irrigation fluids for neurosurgery on brain primary cell cultures

Summary Primary cell cultures from newborn rat brain hemispheres were exposed to different irrigation fluids used in neurosurgery. The cells died after incubation for 5 min with hydrogen peroxide, and the number of cells was drastically decreased after 10 sec of incubation. They shrank after incubation in Elliott's artificial cerebrospinal fluid for 3 h, but the viability as determined by trypan blue exclusion test was not affected. Physiological sodium chloride, Ringer's solution and the culture medium 199 with Hank's salt had no noticeable effect on the viability or morphology of the cells.Acknowledgments. This study was supported by grants from the Medical Faculty of Göteborg and from Statens Naturvetenskapliga Forskningsråd. We want to thank Dr Åke Sellström and Dr Hans-Arne Hansson for valuable discussions.     

报废陶瓷汽车催化剂氯化过程中Pt的挥发行为研究

本文研究了各种条件下报废陶瓷汽车催化剂中元素铂和氯气在700℃反应过程中铂的氯化物的挥发行为。结果表明，在催化剂中添加氯化钠或活性炭都能使氯化过程中铂的氯化物挥发性降低。增加一氧化碳预处理温度至700℃，增加氢气预处理温度至500℃，增加氧气预处理温度至700℃都能使氯化过程中铂的氯化物挥发性能显著增加。     

Reactions of sodium hypochlorite with some compounds having reactive methylene groups

Summary Alkaline sodium hypochlorite solution oxidises a number of compounds having reactive methylene groups to the corresponding gem diols, but in some cases only decarboxylation occurs at room temperature.     

Über den Einfluss von Natriumsulfit,Natriumtellurit und Natriumselenit auf die Retention von Zink,Kadmium und Quecksilber im Organismus

Summary The influence of sodium sulfite, sodium tellurite and sodium selenite on the retention of zinc, cadmium and mercury in mice was studied. The retention of mercury was increased by sodium selenite and by sodium tellurite. The retention of cadmium was increased only by sodium selenite. Sodium sulfite did not influence the retention of metals studied. The retention of zinc was not influenced by any compounds used.