UPR/纳米SiO2复合材料的制备

目前UPR／纳米SiO2复合材料的制备方法有包括原位聚合法、共混法、分子自组装及组装法，研究了UPR／纳米SiO2复合材料的优异性能，并对其增韧机理作了探讨，展望了纳米改性不饱和聚酯树脂复合材料的应用前景。     

纳米SiO_2改性不饱和聚酯树脂的研究进展

综述了国内纳米SiO2改性不饱和聚酯树脂(UPR)研究的最新进展,重点介绍了纳米SiO2用量、粒子尺寸、表面改性处理等因素对纳米SiO2/UPR复合材料性能的影响及纳米粒子增韧增强的机理,指出了纳米SiO2改性UPR存在的问题和可能的发展方向。     

UPR/GF/纳米SiO2复合材料的摩擦学性能和力学性能研究

采用手糊成型室温固化的方法制备纳米SiO2/玻璃纤维(GF)布混杂增强不饱和聚酯树脂(UPR)复合材料,并对UPR复合材料的摩擦学性能和力学性能进行了研究。结果表明,加入纳米SiO2和GF布能大幅提高复合材料的摩擦学性能和力学性能。当复合材料中纳米SiO2含量分别为0.5%(质量分数,下同)和1%时,复合材料的耐磨性分别是纯UPR的5.3倍和3.1倍,拉伸强度是纯UPR的5.8倍和5.1倍,弯曲强度是纯UPR的3.9倍和3.2倍左右。在实验条件下,以含量为0.5%纳米SiO2和GF布混杂填充UPR复合材料的改性效果最好。扫描电镜分析表明,纯UPR的磨损机理是黏着磨损,复合材料磨损机理主要表现为黏着磨损和磨粒磨损。     

纳米SiO2增强增韧不饱和聚酯树脂的研究

用未经表面处理和经表面处理的纳米SiO2对不饱和聚酯树脂(UPR)进行填充改性，研究了纳米SiO2用量对UPR的拉伸强度、弯曲强度、冲击强度的影响。结果表明，当纳米SiO2填充量为6％时，材料的增强增韧效果最好，而且当粉体的加入量为4％～6％时，UPR／SiO2出现了明显的脆韧转变。用DSC测定复合材料的玻璃化温度(Tg)，可以发现复合材料的了Tg比纯UPR大，且烷基化纳米SiO2填充的UPR的Tg更高，这与力学性能结果一致：原位共混法可以实现纳米SiO2的良好分散，相应地具有更好的增韧效果。     

不同制备方法对纳米SiO2/NR复合材料力学性能的影响

本文研究了不同制备方法对纳米SiO2/NR复合材料力学性能的影响,结果表明:乳液共凝法制备的纳米SiO2/NR复合材料的力学性能优于机械共混法制备的纳米SiO2/NR复合材料力学性能.而先用硅酸钠和乙酸乙酯等制备纳米SiO2乳液,再与天然胶乳共凝的方法比用市售纳米SiO2与天然胶乳共凝的方法,纳米SiO2/NR复合材料...     

PC/纳米SiO2复合材料的热降解行为

采用熔融共混法制备了聚碳酸酯(PC)/纳米二氧化硅(SiO2)复合材料。采用X射线衍射和扫描电子显微镜研究了PC和PC/纳米SiO2复合材料的结构,采用热重分析了PC和PC/纳米SiO2复合材料的热降解行为,用Kissinger-Akahira-Sunose法研究了PC和PC/纳米SiO2复合材料的热降解动力学。结果表明:PC的内部结构没有发生变化,且纳米SiO2在基体中分散均匀;加入纳米SiO2能显著改善PC的热稳定性,且PC和PC/纳米SiO2复合材料的热降解温度均随升温速率提高呈线性增加;PC和PC/纳米SiO2复合材料的热降解活化能均随转化率升高而增加,且PC/纳米SiO2复合材料的活化能明显高于PC。     

纳米SiO2／胶清橡胶复合材料力学性能的研究

采用乳液共混法,研究了纳米SiO2/胶清橡胶复合材料的力学性能.结果表明,采用乳液共混法制备纳米SiO2/胶清橡胶复合材料的力学性能优于机械共混法.纳米SiO2改性剂(硅烷偶联剂 TESPT)用量为7.5%～10%,搅拌时间为30min,纳米SiO2用量为20～30份,可制备出力学性能较好的纳米SiO2/NR复合材料.     

接枝烯丙基的碳纳米管改性不饱和聚酯树脂的电性能

在碳纳米管(CNT)上接枝烯丙基,将微量接枝后的碳纳米管(ACNT)加入到不饱和聚酯树脂(UPR)中制备出CNT/UPR和ACNT/UPR纳米复合材料。研究了纳米复合材料的电性能,结果表明:ACNT/UPR纳米复合材料的电性能明显优于CNT/UPR纳米复合材料的电性能。ACNT质量分数为0.075%时,ACNT/UPR纳米复合材料相对纯UPR的体积电阻率和耐电弧性有较大的提升,击穿场强略有增加,表面电阻率降低。     

纳米SiO_2/NR复合材料老化性能的研究

本文研究了纳米SiO2/NR复合材料制备方法。硅烷偶联剂Si69用量和纳米SiO2用量对纳米SiO2NR复合材料力学性能和老化性能的影响。结果表明,乳液共凝法制备的纳米SiO2NR复合材料力学性能和耐老化性能优于机械共混法制备的纳米SiO2NR复合材料力学性能和耐老化性能。加入Si69后,纳米SiO2NR复合材料力学性能和耐老化性能得到改善。在天然橡胶中加入纳米SiO2,改善了天然橡胶的力学性能和耐老化性能。     

纳米SiO_2改性PMMA性能的试验研究

采用本体原位生成法制备了PMMA/SiO2纳米复合材料,并对PMMA/SiO2纳米复合材料体系进行了性能研究。     

N-异丙基丙烯酰胺高分子水凝胶研究进展

N-异丙基丙烯酰胺基高分子水凝胶的研究进展做了综述。简要介绍了该类水凝胶的合成方法,重点分析了不同共聚单体及交联剂对水凝胶溶胀性能和环境响应性的影响,尤其是快速响应水凝胶的合成方法和N-异丙基丙烯酰胺/天然大分子水凝胶的特点。本文也简单介绍了该类水凝胶在不同领域内的应用。     

Proteolytic Activity of the Amoeba Mayorella Palestinensis

Lyophilized preparations of the soil amoeba Mayorella palestinensis hydrolyzed hemoglobin. Maximum cleavage occurred near pH 3. Mercapto compounds enhanced the activity only slightly, versene and iodoacetamide had no influence. Synthetic oligopeptides were also hydrolyzed by the preparations. Maximum degree of cleavage occurred at neutral or slightly alkaline pH values. While L-leucylglycine was readily hydrolyzed, the D-isomer of this peptide was not attacked. With DL-leucylglycine 50% cleavage was obtained. Carbobenzoxy-glycyl-L-phenylalanine and DL-α-bromoisocaproyl glycylglycine were not hydrolyzed while glycyl-L-phenylalanine and DL-leucylglycylglycine were readily cleaved. Hemoglobin was very poorly hydrolyzed by the preparations at neutral or slightly alkaline pH values. However, preincubation of hemoglobin with the preparations at pH 2.7 rendered it available for further appreciable hydrolysis at pH 8. The significance of these findings for understanding the process of protein digestion in the food vacuole of protozoa is discussed.     

纳米技术在药物制剂研究中的应用

药物的水难溶性以及由此导致的低生物利用度是阻碍药学发展的主要原因之一,随着纳米技术的发展以及在药物制剂研究的应用,有些水难溶药物生物利用度低的问题已经得到了较好的解决.本论文在对纳米技术进行简介的基础上,重点介绍了该技术在微乳液、固体脂质纳米粒、纳米凝胶、聚合物纳米粒及纳米结晶等新型给药系统中的应用.在介绍纳米药物相对于传统药物的主要优势时,也对纳米技术在药物制剂研究中潜在的问题也进行了提示,以使纳米技术在新型药物制剂的研究中发挥更好作用.     

Toxic inhibition of some dehydrogenases by methyl sterculate--a natural occurring substance in cotton seeds

According to the present study, crude preparations of rainbow trout liver and rabbit muscle lactate dehydrogenase (LDH,EC 1.1.1.27) were not inhibited by methyl sterculate and oleate, while trout liver glucose-6-phosphate dehydrogenase (G6PDH,EC 1.1.1.49) was activated by these esters. Methyl sterculate inhibited purified preparations of trout liver, rabbit muscle, and bovine heart LDH in contrast to methyl oleate which inhibited only a portion of the activity of purified rabbit muscle LDH and had no appreciable effect on the activities of the other purified LDH preparations. Trout liver LDH preparations were not inhibited by p-Chloromercuribenzoate (pCMB), while rabbit muscle and bovine heart LDH were sensitive to the presence of this inhibitor. Trout liver G6PDH was activated at the lower concentrations of pCMB. These data suggest that the reduction of the activities of liver dehydrogenases in the rainbow trout fed a diet containing methyl sterculate was not due to inhibition of these dehydrogenases by this cyclic fatty acid.     

In vitro metabolism of a linear furanocoumarin (8-methoxypsoralen,xanthotoxin) by mixed-function oxidases of larvae of black swallowtail butterfly and fall armyworm

Studies were made of the comparative in vitro metabolism of [¹⁴C]xanthotoxin and [¹⁴C]aldrin by homogenate preparations of midguts and bodies (carcass minus digestive tract and head) of last-stage larvae of the black swallowtail butterfly (Papilio polyxenes Fabr.) and the fall armyworm [Spodoptera frugiperda (J. E. Smith)]. The two substrates were metabolized by 10,000g supernatant microsomal preparations from both species. Evidence gained through the use of a specific inhibitor and cofactor indicated that mixed-function microsomal oxidases were major factors in the metabolism and that the specific activity of this enzyme system was considerably higher in midgut preparations fromP. polyxenes than in similar preparations fromS. frugiperda. Aldrin was metabolized 3–4 times faster byP. polyxenes, and xanthotoxin 6–6.5 times faster.     

二氧化氯的性质、制备及应用

二氧化氯是一种新型高效的杀菌消毒剂，本文详尽地叙述了二氧化氯的性质、应用及各种制备方法，对稳定性二氧化氯及固体二氧化氯的性质、用途也做了详细的报道。     

脂质体的研究新进展

脂质体作为新型药物载体,在提高药物制剂稳定性及提高药物靶向性等方面有了实质性进展,具有广阔的应用前景,综述了近年来国内外脂质体的制备技术、作为药物载体的应用及最新发展动态。     

高吸水性树脂的制备及应用

主要介绍了高吸水性树脂的分类,制备方法及应用。     

Enzymatic saccharification of canola meal

For the enzymatic saccharification of canola meal by enzyme preparations from Trichoderma reesei as well as by commercially available hemicellulase and multienzyme preparations, a pretreatment consisting of autoclaving is necessary. These enzyme preparations hydrolysed over 20% (w/w) of pretreated canola meal, which constitutes over 70% saccharification of the total polysaccharides present in canola meal. The results show that saccharification of canola meal is mainly brought about by hemicellulases capable of degrading arabinogalactan, arabinoglucan, galactan and galactomannan, while cellulases and xylanases play a minor role. These hemicellulases were found to be more stable at 50°C than cellulases or xylanases. This pretreatment also released water-soluble polysaccharides consisting mainly of arabinose and glucose. Trichoderma reesei was unable to produce enzymes capable of hydrolysing this polysaccharide when cultivated on canola meal as substrate.     

Variations in isomer distribution in commercially available conjugated linoleic acid

Conjugated linoleic acid (CLA) has been reported to have anticarcinogenic and antiatherogenic properties, to repartition body fat, to build bone mass, to normalize glucose tolerance, and to reduce hyperglycemia and diabetes. CLA products are now commercially available, and there is considerable interest in studying CLA because of this range of reported beneficial effects. However, little is known about the composition of these preparations. Representative commercial CLA products in capsule or liquid (aqueous or oily) form were analyzed for their CLA content and isomer composition using gas chromatography (GC), silver ion-high performance liquid chromatography (Ag⁺-HPLC) and spectroscopic techniques. The content of CLA in the preparations varied widely. Based on the GC-internal standard technique, total CLA varied from 20 to 89% by total weight and 28 to 94% of total fat. One product contained no CLA. The isomer distributions were generally of two types: those with two major CLA positional isomers, and those with four major CLA positional isomers. All the CLA preparations in capsule form contained the four isomer mixture, while the liquid preparations contained from two to four CLA positional isomers.