DL-精氨酸/石墨烯修饰电极测定铅

用循环伏安法制备DL-精氨酸/石墨烯修饰玻碳电极,研究金属铅在修饰电极上的电化学行为。在0.1 mol/L pH=4.5的NaAc-HAc缓冲液中,以DL-精氨酸/石墨烯修饰电极作为工作电极,用循环伏安法测定-1.0~1.0 V处的溶出峰电流。实验结果显示:铅的浓度与溶出峰电流具有良好的线性关系,范围是3.0×10-9~9.0×10-7mol/L,检测限为1.0×10-10mol/L,用于测定金属结果满意。     

与环境友好的化学-生物法制备D-精氨酸和L-瓜氨酸

L-精氨酸在水溶液中利用自身所产生的碱性溶液,用n(水杨醛):n(1-精氨酸)=0.1:1的水杨醛为催化剂,L-精氨酸可以快速消旋为DL-精氨酸.后以DL-精氨酸为底物,利用粪链球菌(streptococcus faecalis)精氨酸脱亚胺酶对L-精氨酸的专一脱亚胺作用,同时制备D-精氨酸和L-瓜氨酸,分别以92.3%、94.2%产率获得光学纯的D-精氨酸和L-瓜氨酸.     

天然黑色素改性聚氨酯及紫外遮蔽线性能的研究

采用聚氨酯与天然黑色素通过物理共混制备得到聚氨酯/天然黑色素复合材料(PU/M),主要研究了不同天然黑色素含量对聚氨酯的紫外遮蔽性能和力学性能的影响。结果表明,天然黑色素的引入,明显提高聚氨酯的紫外遮蔽性能,当质量分数2%时,亚甲基蓝溶液仅降解22%;同时天然黑色素赋予聚氨酯更佳优异的力学性能,当质量分数1%时,力学性能达到最佳。     

杏核壳对阳离子染料的吸附研究

本文以杏核壳作为吸附剂,用扫描电镜、红外光谱分析了其表面结构,考察了吸附时间、溶液pH值、染料初始浓度、温度对吸附亚甲基蓝和中性红的影响,并对吸附等温过程和吸附动力学进行了数学模型拟合.结果表明:在染料浓度为50 mg·L-1,吸附剂加入量为6g·L-1,自然pH值,吸附温度25℃,吸附时间为360 min的条件下,杏核壳对亚甲基蓝和中性红有较好的吸附效果,其吸附率都超过90％.Langmuir等温吸附方程能更好地描述杏核壳对两种染料的吸附,准二级动力学模型适合亚甲基蓝的吸附行为,中性红的吸附行为更符合准一级动力学模型.根据红外光谱图及扫描电镜图的分析,可以得出杏核壳对亚甲基蓝和中性红的吸附主要为物理和化学变化共同存在的过程.     

固定化细胞酶法拆分DL-精氨酸

以DL-精氨酸为原料,用固定化细胞酶法拆分DL-精氨酸,并对拆分条件进行了研究。结果表明:最适反应温度55℃,最适pH=6.0,c(DL-精氨酸)=0.3 mol/L,ρ(菌体)=30 g/L,拆分反应10 h,拆分率达98%以上。连续反应10批次,固定化细胞仍保留最高酶活力的75%。产物经分离纯化,D-精氨酸收率达84.0%,[α]2D5=-27.4°〔ρ(D-精氨酸)=20 g/L,5 mol/L盐酸〕。     

葛根素结构修饰及活性的研究进展

葛根素,一种天然异黄酮类化合物,拥有广泛的药理活性;但受天然结构的影响,使葛根素的脂溶性和水溶性均较差,药效发挥受到限制。为了改善葛根素的生物活性,研究者们进行了大量的结构修饰工作,改变了葛根素的原有性质,提高了其在体内的生物利用度。本文以修饰位点分类,对近些年来葛根素的结构修饰及衍生物活性研究进行综述,以期为葛根素相关药物的研发提供参考。     

提高果壳活性炭得率研究

用化学法和化学-物理法制备果壳（杏核、松子壳、核桃壳等）颗粒活性炭，并同时对诸影响因素作了研究，其中化学法杏核炭的得率为34.2%，这较传统物理法活化在得率上高出近两倍；化学-物理法的杏核炭的得率为48.1%，经过对各项指标的检测，化学法制备的活性炭可用作木质净水用炭和木质味精用炭，后者可用作提金奖。     

微波辐照巴旦杏核壳制备活性炭及其吸附性能研究

以巴旦杏核壳为原料,采用微波辐照法制备活性炭。考察了活化条件对活性炭得率和吸附性能的影响。研究结果表明,在活化剂种类、活化剂用量、微波功率和辐照时间4个因素中,微波辐照时间对活性炭质量指标影响最大,延长时间可以提高其产品的得率和吸附性能。巴旦杏核壳基质活性炭的最佳制备工艺：巴旦杏核壳10g,固液比1：3（g：mL）,磷酸质量分数40％、浸溃24h,微波功率640W、活化时间16min。在此条件下制得的活性炭的亚甲基蓝吸附值为231．5mg/g,活性炭得率为56．8％。二级动力学模型能很好的描述巴旦杏核壳活性炭对亚甲基蓝大分子的吸附动力学过程。吸附符合Freundlich吸附等温线方程。     

几种干果核壳活性炭的表征与性能比较

以南疆地区盛产的巴旦杏核壳、核桃壳和白杏核壳为原料,采用微波辐照磷酸法分别制备了巴旦杏核壳活性炭（BAC）、核桃壳活性炭（HAC）和白杏核壳活性炭（XAC）,干果核壳基质活性炭的制备工艺：10 g干果核壳以固液比1：3（g：mL）浸渍40%磷酸24 h,微波功率640 W,活化时间16 min。采用物理吸附仪、扫描电镜（SEM）、傅里叶红外光谱（FT-IR）、X射线衍射（XRD）等表征方法比较研究了不同种类干果核壳活性炭性能差异。结果表明：巴旦杏核壳、核桃壳和白杏核壳活性炭的热分解过程、残留基团基本一致,活性炭晶型均以非晶态为主。3类干果核壳活性炭表面分布着大量孔洞,且孔洞主要为0.4~1.2 nm的微孔和3~6 nm的中孔。其中,白杏核壳活性炭的性能最优,BET比表面积达981.5 m²/g,总孔容达0.570 cm³/g,亚甲基蓝吸附值达269.6 mg/g,碘吸附值达1 162.8 mg/g。     

天然产物活性组分的糖基化修饰研究进展

天然产物广泛存在于自然界中,其数量种类繁多且结构复杂多样,具有许多生理与药理活性。糖基化修饰能增加天然产物结构和功能的多样性,已成为当今新药开发的研究热点。文章归纳了不同结构类型的天然产物糖基化修饰的国内外研究现状与特点,并从糖的连接位置、数量及种类等方面描述糖基化修饰对天然产物水溶性、药理活性和生物利用率等方面的影响,为天然产物糖基化的开发与应用提供参考。     

Sapindaceae,cyanolipids, and bugs

Scentless plant bugs (Heteroptera: Rhopalidae) are so named because adults of the Serinethinae have vestigial metathoracic scent glands. Serinethines are seed predators of Sapindales, especially Sapindaceae that produce toxic cyanolipids. In two serinethine species whose ranges extend into the southern United States,Jadera haematoloma andJ. sanguinolenta, sequestration of host cyanolipids as glucosides renders these gregarious, aposematic insects unpalatable to a variety of predators. The blood glucoside profile and cyanogenesis ofJadera varies depending on the cyanolipid chemistry of hosts, and adults and larvae fed golden rain tree seeds (Koelreuteria paniculata) excrete the volatile lactone, 4-methyl-2(5H)-furanone, to which they are attracted.Jadera fed balloon vine seeds (Cardiospermum spp.) do not excrete the attractive lactone. Loss of the usual heteropteran defensive glands in serinethines may have coevolved with host specificity on toxic plants, and the orientation ofJadera to a volatile excretory product could be an adaptive response to save time.Mention of a commercial product does not consititute an endorsement by the USDA.     

2008～2009年世界塑料工业进展

收集了2008年7月～2009年6月世界塑料工业的相关资料,介绍了2008～2009年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况。按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、环氧树脂、不饱和聚酯树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.