环己烷衍生物及其它几个化合物的构象分析

通过对环己烷衍生物、γ－内酯衍生物、过氧化氢及过硫化氢的构象分析,说明构象分析对有机化学的重要性     

用Cobb－Douglas函数模型分析和预测玉米螟产卵期

本文用Ｃｏｂｂ－Ｄｏｕｇｌａｓｓ（库伯—道格拉斯）函数模型对越冬代玉米螟的产卵期进行了分析。结果表明：ｙ＝２８１３１１９８５．５ｘ－３．６９６８１ｘ－０．７５２８２ｘ－０．１８８４３可以提供较多的内涵专业信息，并可对越冬代玉米螟的产卵期进行预测     

薄层扫描法测定复方氨酚烷胺胶囊中人工牛黄的含量

本文以硅胶Ｇ为吸附剂,环己烷－醋酸乙酯－冰醋酸（４：４：１）为展开剂,采用双波长薄层扫描法测定了复方氨酚烷胶囊中人工牛黄的有效成分－胆酸的含量,测定波长λｓ＝３８５ｎｍ,参比波长λＲ＝６００ｎｍ。测得平均回收率为９８．４５％,ＲＳＤ为１．６６％。     

离子注入诱变选育之江菌素产生菌

以之江菌素产生菌玫瑰黄链霉菌杭州亚种93－15－32菌株为出发菌，研究离子注入微生物的诱变效应。结果表明，各剂量N^ 离子注入之江菌素产生菌的总变异率达42．4％－73．0％，其中正变异率达5．8％－38．2％。通过9批诱变实验，筛选到一株高产菌株94－49，效价比出发菌株提高4倍多。通过5代传代，产素性能能稳定遗传，并通过了400L发酵罐中试。实验结果表明，离子注入处理是一种有潜力的微生物诱变育种新方法。     

银离子络合萃取法分离纯化烟叶中茄尼醇的研究

最佳工艺为称取茄尼醇粗品浸膏,加三十毫升环己烷溶解浸膏,加三十毫升40%的硝酸银溶液,二十五摄氏度下搅拌60分钟,离心收集沉淀,萃取法分离两次。针对银离子络合萃取法分离纯化烟叶中茄尼醇的工艺进行研究。     

以酮类为衍生剂气相色谱法测定碘的研究

以酮类为衍生剂利用气相色谱法测定痕量碘，探讨四种酮与碘的衍生反应条件，并对生成的碘代酮作了质谱鉴定。对碘代酮在不同类型的填充柱上的气相色谱行为以及最佳参数进行了试验。碘代酮对电子捕获检测器响应值大小的次序为：碘代戊酮＞碘代丁酮＞碘代甲基异丁酮＞碘代丙酮。碘代戊酮的响应值比碘代丙酮高十倍，用此法可测定天然水中１０－８克数量级的碘。关键词     

光敏引发剂α-羟基环己基苯甲酮合成的改进

以苯甲醛、镁、溴代环己烷、溴等为主要原料,经 4步反应合成了光敏引发剂α 羟基环己基苯甲酮,改进了其制备过程中第二步的氧化和第三步溴代反应。其中第二步是以氯仿作溶剂,新洁尔灭作相转移催化剂,在室温下进行反应。与原工艺比较,副产物少,后处理简单,收率高。第三步是以四氯化碳作溶剂,醋酸作催化剂进行溴代反应。改进后的合成方法具有工艺简单、成本低、收率高等特点。     

N—环己基硫代酞酰亚胺新合成路线探讨

阐述了Ｎ－环己基硫代酞酰亚胺合成方法，该方法具有降低生产成本，减少环境污染，增加操作安全性的优点，根据实验数据，详细讨论了影响合成的主要因素并得出较佳工艺条件。     

N－环己基硫代酞酰亚胺新合成路线探讨

阐述了Ｎ－环己基硫代酞酰亚胺新合成方法．该方法具有降低生产成本，减少环境污染，增加操作安全性的优点．根据实验数据，详细讨论了影响合成的主要因素并得出较佳工艺条件．     

同位素取代甲醛分子光谱性质的密度泛函理论研究

用密度泛函方法B3LYP／6－31G＊＊对甲醛和氘代甲醛进行几何构型全优化，优化的结果与实验值吻合，用上述方法对甲醛、各种氘代甲醛和氘代甲醛分子进行了分子的振动基频和热力学性质计算。计算结果表明甲醛和氘代甲醛标度后振动频率的计算值与实验值的最大相对偏差为4.1%，最小的相对偏差为0.34%。甲醛分子的等容热容和熵随着氘取代原子数的增加而增加；而总能和焓却随之减小。     

Evaluation of the ability to metabolize 1,2-propanediol by heterofermentative bacteria of the genus Lactobacillus

BackgroundNew directions of research on lactic acid bacteria include investigation of metabolic pathways for the synthesis and/or metabolism of 1,2-propanediol, commonly used in the food and chemical industry, medicine, pharmacy and cosmetology as well as agriculture. The objective of this study was to compare the capacity of strains representing three diverse heterofermentative species belonging to the genus Lactobacillus to synthesize and/or transform 1,2-PD as well as to suggest new directions of research aimed at commercial use of this metabolite.ResultsThe novel strain of Lactobacillus buchneri A KKP 2047p, characterized as exhibiting an unusual trait for that species in the form of capacity to metabolize 1,2-PD, grew poorly in a medium containing 1,2-PD as a sole carbon source. The supplementation with glucose facilitated rapid growth of bacteria and use of 1,2-PD for the synthesis of propionic acid. A similar observation was noted for Lactobacillus reuteri. On the other hand, Lactobacillus diolivorans effectively metabolized 1,2-PD which was the sole carbon source in the medium, and the addition of glucose inhibited the synthesis of propionic acid. The experiments also investigated the effect of cobalamin as a diol dehydratase coenzyme involved in the propionic acid synthesis from 1,2-PD whose addition promoted the yield of the reaction in the case of all tested strains.ConclusionsAll tested isolates showed the ability to effectively metabolize 1,2-PD (in the presence of cobalamin) and its conversion to propionic acid, which reveals that investigated bacteria meet the essential requirements of microorganisms with a potential application.     

The Control of Sandstorms in Inner Mongolia

The frequent occurrence of sandstorms in north China in recent years had an immediatebearing upon the ecological degeneration of grasslands in Inner Mongolia. The long-time preda-tory exploitation of the primordial ecosystems leads to the degradation of the sandy grasslands.In this aspect, human infringement is the predominant reason while natural retrogression issecondary. In the taming of the sandstorm scourge, therefore, the key lies in casting off the live-stock-grazing pressure on the de…     

Enhancement of biodegradation potential of catechol 1,2-dioxygenase through its immobilization in calcium alginate gel

BackgroundIn biodegradation processes free enzymes often undergo deactivation. Thus, it is very important to obtain highly stable enzymes by different methods. Immobilization allows for successful stabilization of many multimeric enzymes by increasing the rigidity of the enzyme structure. This study aimed to evaluate some environmental factors that affect catechol 1,2-dioxygenase from Stenotrophomonas maltophilia KB2 immobilized in alginate hydrogel. The goal of the present work was to improve the functional stability of the enzyme by increasing its structural rigidity.ResultsImmobilization yield and expressed activity were 100% and 56%, respectively. Under the same storage conditions, the activity of the immobilized enzyme was still observed on the 28th d of incubation at 4°C, whereas the free enzyme lost its activity after 14 d. The immobilized enzyme required approximately 10°C lower temperature for its optimal activity than the free enzyme. Immobilization shifted the optimal pH from 8 for the soluble enzyme to 7 for the immobilized enzyme. The immobilized catechol 1,2-dioxygenase showed activity against 3-methylcatechol, 4-methylcatechol, 3-chlorocatechol, 4-chlorocatechol, and 3,5-dichlorocatechol. The immobilization of the enzyme promoted its stabilization against any distorting agents: aliphatic alcohols, phenols, and chelators.ConclusionsThe entrapment of the catechol 1,2-dioxygenase from S. maltophilia KB2 has been shown to be an effective method for improving the functional properties of the enzyme. Increased resistance to inactivation by higher substrate concentration and other factors affecting enzyme activity as well as broadened substrate specificity compared to the soluble enzyme, makes the immobilized catechol 1,2-dioxygenase suitable for the bioremediation and detoxification of xenobiotic-contaminated environments.     

Unambiguous evidence of brilliant iridescent feather color from hollow melanosomes in an Early Cretaceous bird

Various plumage colors are roughly produced by pigment-based colors and structural colors[1,2].Brilliant iridescent plumage colors(in which the color changes de...     

Microfluidic generation of droplet interface bilayer networks incorporating real-time size sorting in linear and non-linear configurations

In this study, a novel droplet based microfluidic method for the generation of different sized droplet interface bilayers is reported. A microfluidic platform was designed, which allows the generation and packing of picoliter lipid coated water droplets. Droplets were generated by hydrodynamic focusing coupled with selective transport along grooves according to their size. A trapping structure at the end of the groove and a fine control of the flow pressures allowed for the droplets to be successfully trapped and aligned on demand. This technology facilitates the fine control of droplet size production as well as the generation of extended networks from a variety of lipids including 1,2-diphytanoyl-sn-glycero-3-phosphocholine and 1,2-dioleoyl-sn-glycero-3-phosphocholine in linear and non-linear configurations, which is vital to the application of Droplet Interface Bilayers to biological network construction on-chip.     

基于产生式规则的排序算法

给出了产生式规则的排序算法,以提高复杂问题的求解速度.实验证明,该算法不仅可用于规则静态排列,而且适宜规则动态排列.     

连州发电厂#2机组汽轮机测速装置改造

广东省连州发电厂#1、2机组使用的是上海汽轮机厂生产的125MW汽轮机,由于汽轮机转速测速齿轮盘晃动将转速探头磨损,差点造成汽机超速保护误动或汽机超速失控而转速保护拒动失效造成"飞车"等险情。将转速测速齿轮盘进行改造后避免了探头的磨损,提高了机组运行安全性。     

特殊图的最优标号

标号图(G,L)由图G和它的标号L∶V(G)→{1,2,…,n｝组成.其中n=|V(G)|.在标号图(G,L)中,如果一条路P=u1,u2,…,uk(k≥1)的长度为0(k=1)或者对任意的i(i=1,2,…,k-1;k＞1),满足L(ui)+2≥L(ui+1),则称P为不连续增长路.标号(G,L)图中所有的不连续增长路的数目记为d(G,L).如果图G的一种标号L使得d(G,L)达到最大,则称之为图G的最优标号.在这里,给出了毛毛虫图的一种最优标号.     

CY3菌株代谢中间产物的氧化产物的分析与鉴定

实验通过研究发现CY3菌株不但能代谢原始的多环芳烃,还可以在很短的时间内将中间产物代谢掉,从而使这些中间产物不易积累。通过GC-MS来鉴定CY3菌株将1-羟基-2-萘甲酸降解为1-羟基萘,1,2-二羟基萘等。     

Phase segregation of polymerizable lipids to construct filters for separating lipid-membrane-embedded species

Supported lipid bilayer (SLB) platforms have been developed to transport and separate membrane-embedded species in the species'' native bilayer environment. In this study, we used the phase segregation phenomenon of lipid mixtures containing a polymerizable diacetylene phospholipid, 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine (DiynePC), and a nonpolymerizable phospholipid, 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), to create filter barrier structures in SLBs. Upon exposing the phase segregated samples to UV light, the DiynePC-rich domains could become crosslinked and remain fixed on the surface of the support, while the DOPC-rich regions, where no crosslinking could happen, could be removed later by detergent washing, and thus became the void regions in the filter. During the filter fabrication process, we used the laminar flow configuration in a microfluidic channel to control the spatial locations of the feed region and filter region in the SLB. The flow in a microfluidic channel was also used to apply a strong hydrodynamic shear stress to the SLB to transport the membrane-embedded species from the feed region to the filter region. We varied the DiynePC/DOPC molar ratio from 60/40 to 80/20 to adjust the cutoff size of the filter barriers and used two model membrane-embedded species of different sizes to examine the filtering capability. One of the model species, Texas Red 1,2-dihexa-decanoyl-sn-glycero-3-phosphoethanolamine triethylammonium salt (Texas Red DHPE), had a single-lipid size, and the other species, cholera toxin subunit B-GM1 complex, had a multilipid size. When the DiynePC/DOPC molar ratio was 60/40, both species had high penetration ratios in the filter region. However, when the ratio was increased to 70/30, only the Texas Red DHPE, which was the smaller of the two model species, could penetrate the filter to a considerable extent. When the ratio was increased to 80/20, neither of the model species could penetrate the filter region. The results showed the possibility of using phase segregation of a mixture containing a polymerizable lipid and a nonpolymerizable lipid to fabricate filter barrier structures with tunable cutoff sizes in SLBs.