气辅外门拉手用PC/PBT合金材料研究

介绍了动力锂离子电池对隔膜的性能要求,分析了现有的聚烯烃隔膜的特点及缺陷,并综述了目前各类型动力锂离子电池隔膜的研究成果,讨论了改性聚烯烃隔膜、改性无纺布隔膜及其他隔膜的特点及应用情况。另外,指出了安全性及均一性是动力锂离子电池隔膜的最基本要求及关键性能。     

软起动的介绍及应用

从软起动的定义着手,指出了电机直接起动的要求及危害,介绍了软起动的工作原理、控制方式及技术特点,结合软起动的应用条件,通过计算验证了起动过程电压下降满足设计规范的要求,阐述了软起动的调试及同步电机软起的起动过程。总结列出了常见故障现象及处理方法,最后从运行的角度分析了应用效果及注意事项。     

甲基磺酸盐在锡及锡基合金镀层中的应用现状

介绍了甲基磺酸(MSA)盐镀液体系的特点。分析了电镀锡及可焊性锡合金镀液的主要成分及特点,介绍了MSA体系在电镀锡钢板中的应用。对比了电镀无铅镀层和Sn–Pb合金镀层的性能,给出了电镀及化学镀锡及锡基合金的工艺配方及操作条件。     

国外氯乙酸的生产及市场分析

概述了国外氯乙酸的生产情况、消费结构及商情,提供了国外主要生产厂家及生产规模,阐述了氯乙酸用途及工业开发前景。     

纳米技术、纳米材料及其在纺织工业上的应用

概述了纳米技术的起源及发展,介绍了纳米材料的结构及性质,对其在高分子复合材料及纺织工业上的应用进行了综述。     

结晶及沉淀过程中粒子聚结与团聚的研究进展

粒子聚结及团聚是结晶及沉淀过程中重要的二次动力学过程,对最终产品的晶形、粒度分布及纯度影响较大。综述了粒子聚结及团聚过程的机理及其影响因素,讨论了有关数学模型的研究进展,并对聚结与团聚的研究方向进行了展望。     

新型卟啉化合物的合成应用新进展

简要介绍了卟啉类化合物的结构特征、性质及应用;重点综述了新型卟啉化合物及金属配合物的合成及应用;新型卟啉衍生物的合成及选择性识别;新型卟啉衍生物的合成及在光学方面的应用。并对卟啉化学的发展进行了展望。     

我国磷矿床特征及发展对策建议

简述了我国磷矿矿床类型及基本地质特征,总结了磷矿资源分布特征及开发利用现状,并对磷矿资源需求现状进行了简要分析,着重论述了我国磷矿资源保护、开发、利用及发展的对策及建议。     

铜及铜合金的化学抛光工艺改进

本文介绍了改进的铜及铜合金化学抛光工艺,简介了该工艺的流程,化学抛光液和脱膜液的配方及工艺条件,还分析了硝酸及过氧化氢浓度、乙醇及LC添加剂、抛光时间及搅拌速度等对该工艺的影响。     

现代有机及生物分析在生命科学医药学分析及检测方面的研究

简要介绍了现代有机分析的产生发展及应用,重点综述了现代有机及生物分析在生命科学及医药学分析中的应用;现代有机及生物分析在有机分析分离科学中的应用,并就现代有机及生物分析的发展前景进行了展望。     

The separation of lecithin and soya oil in a countercurrent column by near critical fluid extraction

The present contribution illustrates a way of developing a continuous separation process for near critical fluid extraction, on the example of separation of soya oil from lecithin. First, a suitable solvent was selected. Phase equilibria were measured in autoclaves. Operating conditions for a pilot plant were derived from the phase equilibrium data. The pilot plant experiments provided the necessary data for designing a production plant. Computer programs for phase equilibrium, stage to stage and mass and heat balance calculations were used in order to minimize the number of experiments. A production plant with a capacity of 500 t/a of raw lecithin was designed on the basis of experimental and computational results. A cost estimation, based on tenders, showed that it is more economical to produce lecithin by near critical fluid extraction than by conventional acetone extraction.     

Paper chromatography of phospholipides on silicic acid impregnated glass fiber filter paper

Summary 1. A reasonably reproducible method has been developed for separating lysolecithin, lecithin,, sphingomyelin, and phosphatidylethanolamine, using glass fiber filter paper impregnated with silicic acid as the chromatographic medium and 1:1 methanol:ethyl ether as the developing solvent. 2. Hot sulfuric acid was used to locate the chromatographed compounds on the chromatogram. The advantages and disadvantages of this reagent and the other spot test reagents used were discussed. 3. No separation between the unsaturated and saturated counterparts of lysolecithin or lecithin was obtained. Supported in part by a grant-in-aid from the National Science Foundation.     

Fourier Transform Near Infrared Spectroscopy as a Quality Control Tool for the Analysis of Lecithin and By-Products During Soybean Oil Processing

Fourier transform near infrared (FT-NIR) spectroscopy was used to analyze multiple measurement parameters in lecithin production samples and soybean oil refining by-products. For lecithin, partial least squares (PLS) calibration models were developed for acetone insolubles, acid value and moisture and leave-one-out cross validation of the calibration models yielded root mean square error of cross validation (RMSECV) values of 0.37%, 0.59 (mg KOH/g) and 0.050%, respectively. An independent test set consisting of 40% of the lecithin production samples were predicted from the PLS calibration models and a root mean square error of prediction (RMSEP) of 0.41%, 0.53 (mg KOH/g) and 0.056% were obtained for acetone insolubles, acid value and moisture, respectively. Comparison of FT-NIR predictions and corresponding reference method values of 10 lecithin samples using a two-tailed t test showed no significant difference at the p = 0.05 level. A set of 51 samples of soybean oil refining by-products, including acidulated soapstock, fatty acids and black oil, were used for developing PLS calibration models for measuring acid value, moisture and iodine value and leave-one-out cross validations for each model gave values for RMSECV of 6.59 (mg KOH/g), 0.046% and 0.42 (mg I₂/g), respectively. Overall, the results of this study demonstrate the suitability of FT-NIR spectroscopy for the routine analysis of lecithin production samples and soybean oil refining by-products for quality control purposes.     

Egg-yolk lipid fractionation and lecithin characterization

Egg-yolk lecithin has phospholipid (PL) classes and a FA composition that differ from soybean lecithin and may have unique functional properties. The purposes of this research were to develop an effective method for extracting a sufficient amount to lecithin from fresh egg yolks and to evaluate its functional properties. Ethanol was used to dehydrate and partially extract the PL, after which hexane was used to extract the total lipids. A phase separation of the combined extracts resulted in neutral and polar lipid fractions. An acetone precipitation of PL from the final polar lipid fraction was necessary to remove the residual neutral lipids, especially cholesterol. The purity of PL in the lecithin product was 95%. Surface tension reduction, emulsion stability, and oxidative stability studies were conducted to characterize the functional properties of egg-yolk lecithin. Egg-yolk lecithin and soy lecithin had similar surface activities, as evaluated by the surface tension reduction in an aqueous system and the critical micelle concentration. Soybean lecithin created a more stable emulsion than egg-yolk lecithin. However, egg-yolk lecithin was more oxidatively stable than soybean lecithin.     

Enzymatic hydrolysis of oat and soya lecithin: Effects on functional properties

Enzymatic hydrolysis of oat and soy lecithins and its effects on the functional properties of lecithins were investigated. The phospholipase used was most efficient at low enzyme and substrate concentrations. More fatty acids were released from soy lecithin than from oat lecithin. The maximum degree of hydrolysis was 760 μmol free fatty acids per gram soy lecithin and 170 μmol free fatty acids per gram oat lecithin. On the basis of the total carbohydrate and phosphorus contents in the polar fractions of the lecithins, oat lecithin contained more glycolipids and less phospholipids than soy lecithin. With regard to functional properties, the stability of oil-in-water emulsions was enhanced by hydrolyzed soy lecithin and by crude and hydrolyzed oat lecithins, but only hydrolyzed soy lecithin prevented the recrystallization of barley starch. The dissociation enthalpy of amylose-lipid-complex (AML-complex) was significantly higher when hydrolyzed soy lecithin was present. Hydrolyzed oat lecithin slightly affected the dissociation enthalpy of AML-complex. The other lecithins had no effect on recrystallization or dissociation enthalpies in the barley-starch matrix.     

Effects of expander process on the phospholipids in soybean oil

Crude oils were extracted from soybean flakes and collets by conventional and expander processes, respectively. The phospholipids were removed by degumming, and the lecithins were produced by using commercial procedures. The effects of the expander process on the degumming efficiencies were evaluated. The differences in the phosphatide compositions of the oils and the lecithins produced from expander and conventional processes were compared by high-performance liquid chromatography. The phosphorus content indicated that expander-processed oil contained more phosphorus (985 ppm) than the conventional oil (840 ppm). However, the phospholipids in the expander-processed oil were more hydratable than those in the conventional oil. After degumming, the phosphorus content in the expander-processed and conventional oil were reduced by 93.2 and 78.6%, respectively. The expander-processed lecithin contained 74.3% acetone-insoluble matter (AI), and the conventional lecithin contained 65.8%. More phosphatidylcholine was found in the expander-processed lecithin (39.78%, based on AI) than in the conventionally processed lecithin (34.19%). The phosphatidylinositol contents of the expander-processed lecithin and the conventional lecithin are almost the same (19.95 and 19.97%). The phosphatidylethanolamine in the expander-processed lecithin (12.36%) was lower than that in the conventional lecithin (18.07%).     

The Preparation of Rapeseed Lecithin with High Phosphatidylcholine Content

The raw commercial rapeseed lecithin free of erucic acid and glucosinolate (00-type) was purified by deoiling with acetone and extracting with ethanol. The increasing of phosphatidylcholine (PC) content (from 50 to 70–80%) in obtained rapeseed lecithin extract was performed. It was done by column chromatographic fractionation using a low silica gel–lecithin extract ratio about 2:1 and the various temperatures up to 60°C. The fractions were eluted with 95% ethanol. Effect of rapeseed lecithin column fractionation temperatures is significant and the better purification quality in the higher temperatures was observed. Based on performed investigations it could be summarized that the low silica gel–lecithin extract ratio (2:1) allows to obtain rapeseed lecithin with above 80% content of PC and the best results for temperature 60°C were observed.     

Characterizing Lecithin Interactions in Chocolate Using Interfacial Properties and Rheology

The functionality of chocolate is based on specific properties including how it flows. Cocoa butter and lecithin are two ingredients that help to control the flow properties of melted chocolate. Lecithin is an emulsifier that has been the preferred method of providing yield stress and viscosity control while reducing production costs by decreasing the amount of cocoa butter needed to achieve similar flow results. In this industrially oriented study, soy, sunflower, and dairy lecithin were compared by quantifying interfacial and rheological properties of lecithin in dark chocolate. Each lecithin source was added up to the 1.0% limit, which is the emulsifier maximum set forth by the Code of Federal Regulations. The compositions of each lecithin source were analyzed for total phospholipid composition, which were used to normalize data based on the total added phosphatides added for all samples. Differences in both phosphatide composition and fatty acid composition were found. Both interfacial tension between oil and water phases and contact angle between a cocoa butter drop and flat sucrose crystal surface decreased as the phosphatide concentration increased for each lecithin source. In terms of rheology, the yield stress first decreased with increasing lecithin content and then began to increase, whereas plastic viscosity continually decreased with addition of lecithin. Significant differences were seen for the different lecithin sources, even when compared on an equivalent phosphatide content. No correlations were found between interfacial properties and yield stress; however, direct correlations were found between both interfacial measures and plastic viscosity.     

Lecithin influence on hyperlipemia in rhesus monkeys

Previous studies in humans have shown that the ingestion of lecithin can alter plasma cholesterol and triglyceride concentrations by mechanism(s) that remain to be elucidated. To further explore this response to lecithin, hyperlipemic rhesus monkeys were selected from a group of animals fed a semipurified diet containing corn oil, casein, sucrose and cholesterol (120 mg/100 Kcal) for 10 years. Soybean lecithin (92% phosphatidylcholine) was supplemented in the diet (0.5 g/100 Kcal) of these monkeys. Measurements of plasma cholesterol, triglycerides and phospholipid were made prior to, during and following 7 wk of lecithin supplementation. In addition, determinations of triglyceride secretion rates following administration of Triton WR1339, triglyceride clearance after intravenous infusion of Intralipid^® and plasma lecithin:cholesterol acyl transferase enzyme (LCAT) activity were assessed at the same time intervals. As in other studies, manipulation of lecithin intake elicited a highly variable response, but significant changes were observed in plasma cholesterol and triglycerides as a consequence of supplementing or removing lecithin from the diet. Lecithin had no influence on the absolute plasma phospholipid level or LCAT activity. However, lecithin significantly reduced total lipids, increased the relative concentration of phospholipid and tended to increase the phospholipid/free cholesterol (PL/FC) concentration. While lecithin did not significantly affect triglyceride secretion rates, all animals were able to clear Intralipid^® (triglyceride) more efficiently while fed lecithin. These data are interpreted to mean that the reduction in plasma lipids associated with lecithin ingestion may have been mediated via enhanced clearance of lipids transported in lipoproteins of lower density, whereas the rebound following lecithin removal reflected reduced clearance of these lipids.     

Rapslecithinschlamm als Ausgangsmaterial zur Gewinnung von hochreinem Lecithin

Rapeseed Wet Gum as a Direct Source of High Quality Lecithin The acetone deoiling and dehydration processes of rapeseed wet gum were investigated for deoiled lecithin preparation. The yield, the deoiling efficiency and the quality of lecithins obtained from wet gum were compared with those prepared from the commercial raw lecithin. Besides, the extraction parameters were also discussed. Basing on the performed investigations it could be summarized that the deoiling and dehydration processes are more effective when the lecithin wet gum is used. The quality of deoiled lecithin prepared from wet gum is also better than that obtained from other commercial raw materials.