Poly(vinyl alcohol)/Clay‐Based Nanocomposite Hydrogels: Swelling Behavior and Characterization

Polymer/clay composite hydrogels were prepared based on PVA hydrogels containing 3–10 wt.‐% MOM. Their microstructure and morphology were studied by FT‐IR, WAXS and SEM, whereas the interactions between MOM and PVA were evaluated by thermal analyses. The swelling ratios for the PVA/MOM hydrogels decrease with increasing MOM content. WAXS results indicate that MOM was intercalates, and DSC results show a strong interaction between PVA and MOM. This interaction results in a stable network, which is confirmed by the elastic modulus and the thermal decomposition behavior of the hydrogels. Therefore, MOM acts as a co‐crosslinker, improving the stability of the network.

     

Distribution, diversity and regulation of alcohol oxidase isozymes, and phylogenetic relationships of methylotrophic yeasts

In this study, we attempted to classify the methylotrophic yeasts based on diversities of alcohol oxidase (AOD), i.e. zymogram patterns and partial amino acid sequences. According to zymogram patterns for AOD, members of the methylotrophic yeasts separate into two major lineages, one group involving strains having a single AOD and the other group, including Pichia methanolica, Candida pignaliae and C. sonorensis, showing nine AOD isozymes. Based on partial amino acid sequences of AOD, the methylotrophic yeasts could be divided into five groups, and this classification agrees mostly with grouping based on 26S domain D1/D2 rDNA nucleotide sequences, except for some strains. Moreover, the strains having AOD isozymes constitute one group with P. trehalophila, P. glucozyma and Pichia sp. strain BZ159, although these strains are divided into two types, based on amino acid sequences of second AODs. On the other hand, these AOD isozymes consist of two subunits; the first subunits are induced not only by methanol but also by glycerol and pectin, although the second subunits are mainly induced by methanol. These data indicate that AOD isozymes and second AOD genes distribute widely in several methylotrophic yeasts in the natural environment, and second AOD genes may have evolved as methylotrophic genes that can adapt to the environmental conditions of higher methanol concentrations.     

Acetophenone as an Anti-attractant for the Western Pine Beetle, <Emphasis Type="Italic">Dendroctonus Brevicomis</Emphasis> LeConte (Coleoptera: Scolytidae)

Host location and colonization by bark beetles is dependent upon the relative and absolute amounts of attractant and antiattractant compounds available. Many investigations have lead to use of antiattractants for the management of these pests and have been especially focused on verbenone. However, recent studies have identified new antiattractants for several species of bark beetles. We report results of recent investigations of the response of western pine beetle, Dendroctonus brevicomis LeConte, to two recently identified antiattractants, acetophenone, and fenchyl alcohol, with verbenone as a standard of comparison, in northern California. Release of both acetophenone and verbenone resulted in significantly lower trap catches of D. brevicomis in aggregation pheromone-baited traps, while fenchyl alcohol was inactive. Acetophenone was the only antiattractant that did not reduce numbers of the most abundant predator of D. brevicomis, Temnochila chlorodia (Mannerheim), responding to the attractant pheromone of its prey. Aggregation pheromone-baited traps with acetophenone also had the highest predator/prey ratio. Our results suggest that acetophenone may be part of the intra- and interspecific interactions among sympatric species of bark beetles and may have application in their control.     

载银纳米纤维素/聚乙烯醇复合膜的制备及性能研究

目的制备一种具有良好力学性能和抑菌性能的新型抗菌聚乙烯醇复合膜。方法通过酸水解微晶纤维素制备纳米纤维素,经高碘酸钠氧化获得醛基纳米纤维素,加入银氨溶液原位合成载银纳米纤维素(Ag-DCNC)。以聚乙烯醇(PVA)为成膜基底,加入Ag-DCNC共混流延制备载银纳米纤维素/聚乙烯醇复合膜。结果 Ag-DCNC体积分数为3%时,复合膜的拉伸强度比纯PVA膜提高了8.8%。Ag-DCNC体积分数为5%的复合膜对大肠杆菌和金黄色葡萄球菌均具有较好的抑菌效果。结论载银纳米纤维素/聚乙烯醇复合膜具有较好的力学强度,对2种细菌均有良好的杀菌效果。该材料不但具有良好的性能,而且合成工艺简单,可以作为一种很有前途的抑菌膜用于包装行业。     

湿法纺丝制备水溶性PVA纤维工艺探讨

阐述了制备水溶性聚乙烯醇(PVA)纤维原料的选择,纺丝原液的制备,纺丝及后处理工艺条件。 利用聚合度不大于1 700、醇解度不大于99％的各种牌号PVA,可用湿法纺丝制得溶解温度在60℃以上的水 溶性PVA纤维。     

烷基二甲基叔胺的清洁生产

使用新型高选择性胺化催化剂、回收再利用蒸馏残渣和废胺化催化剂后,每生产1t叔胺,脂肪醇消耗减少至940kg,二甲胺消耗降低至240kg,副产物蒸馏残渣减少至30kg,80％可再利用,反应时间缩短至4h,使得脂肪醇催化胺化工艺变得更加清洁。     

环己烷、正丁醇、甲苯有关二元体系加压相平衡

以环已烷、正丁醇、甲苯为代表,进一步研究了烷烃、芳烃和低级醇在加压下的相平衡规律。测定了有关3个二元体系在101.3、304.0、506.6、709.3、911.9kPa下汽液平衡数据,对实测数据进行了统一关联,计算结果与实测值符合良好。环己烷-正丁醇、正丁醇-甲苯体系在所测压力下均形成最低共沸点。     

环己烷-正丁醇-甲苯三元体系加压相平衡研究

研究了环己烷、正丁醇、甲苯这类醇烃体系的加压汽液平衡行为.根据环己烷、正丁醇、甲苯有关二元体系求得的Wilson能量参数及统一关联式,预测了环己烷-正丁醇-甲苯三元体系在101～911kPa5个压力下的汽液平衡数据,与实测值符合良好.     

分子吸附对聚乙烯醇在氧化铝粉末压缩体中扩散系数的影响

利用氧化铝粉末压缩球状体和Ｆｉｃｋ第二扩散定律,系统地研究了聚乙烯醇在多孔介质和实验系统ｐＨ值为８．４０±０．２条件下的扩散行为,以及聚乙烯醇在球体外表面吸附对扩散系数的影响．实验结果和相应计算得到的扩散系数表明：发生在氧化铝表面的分子吸附,不仅导致扩散平衡状态时的Ｍｔ（聚乙烯醇在时间ｔ的扩散量）高于理论计算值Ｍ∞,而且使实验初始阶段计算的扩散系数远大于其它过程扩散系数．由分子吸附产生的实验误差和扩散系数计算误差,可通过修正浓度分配系数Ｋ,或者直接从Ｍｔ中去除可能存在的吸附量得到解决．