锂离子电池高钴正极片中镍的测定

研究了锂离子电池高钴正极片中常量镍的测定。以酒石酸掩蔽铁、钙、镁等杂质,在pH=5.5~6.0时以丁二酮肟沉淀分离镍,用盐酸溶解沉淀,所得溶液蒸发至近干以破坏丁二酮肟;在pH=10的氨-氯化铵缓冲溶液中以过氧化氢氧化返溶得到的镍液中残留的钴,用EDTA滴定镍。方法的回收率为97.56%~101.92%,RSD为0.56%。     

可伐合金中镍含量的测定

称取适量可伐合金试样,用盐酸、硝酸溶解之,氢氟酸溶解硅,高氯酸冒烟、除碳。以柠檬酸铵作为掩蔽剂,用过氧化氢氧化Co2+成Co3+。在pH=7~8的条件下,镍与丁二酮肟生成丁二酮肟镍沉淀。沉淀陈化一小时后,经140±5℃烘干并恒重。     

丁二酮肟光度法在快速测定铜镍合金中镍含量的应用

为了对铜镍合金中的镍进行快速测定,提出了丁二酮肟光度法,利用盐酸和过氧化氢溶解合金样品,加入柠檬酸铵对三价铁离子进行遮蔽,当介质中存在碘时,丁二酮肟可以与镍生成可溶性酒红色络合物,配合分光光度法,能够实现对镍含量的准确测定。     

三价铬镀铬液中六价铬、铜、铁和镍杂质的分析方法

介绍了三价铬镀铬溶液中六价铬、铜、铁和镍杂质的分析方法。利用二苯氨基脲在酸性溶液中与六价铬的特效显色反应,用光度法测定三价铬镀铬溶液中的六价铬杂质。利用二乙基二硫代氨基甲酸钠与铜离子生成稳定黄棕色络合物的特性,用光度法测定镀液中铜杂质。利用钛铁试剂与三价铁离子在弱碱性条件下生成稳定的红棕色络合物的特性,用光度法测定镀液中的铁杂质。利用丁二酮肟与镍离子生成稳定的红色络合物的特性,用光度法测定镀液中的镍杂质。     

丁二酮肟重量法测定镍钴铝氢氧化物中镍含量

试样经盐酸溶解,以酒石酸氨性溶液掩蔽杂质离子,以丁二酮肟乙醇溶液沉淀镍,沉淀干燥至恒重,建立了镍钴铝氢氧化物中镍含量的测定方法.结果表明:加入10 mL酒石酸溶液掩蔽干扰离子后,大量的钴、铝基体不会对测定造成干扰,滤液中镍含量约为0.04％ ～0.10％之间,无需补正滤液中镍含量,方法分析速度快、结果准确可靠,RSD不...     

铜合金与化学分析方法探讨

本方法采用硝酸一硫酸混合酸溶解试样,以酒石酸钾钠络合主体钼,用电解法和丁二酮肟重量法分别测定钼铜合金中铜和镍的含量。用电解铜后的溶液继续分析镍的含量,既简化了分析程序,又排除了钼和铜对镍的干扰,实现了对钼铜合金中铜和镍的联合测定。本方法分析钼铜合金试验原理可靠,操作简便,精密度好,准确度高。     

分光光度法测定镀铬溶液中铜、铁及镍杂质

介绍了镀铬溶液中铜、铁和镍杂质的快速分析方法.以双环己酮草酰二腙作指示剂,用分光光度法测定铜;以钛铁试剂作指示剂用光度法测定铁;以丁二酮肟作指示剂用光度法测定镍.实验表明,这三种方法的回收率分别为99.2%、99.1%和102%.方法简单,快速而准确,能够满足镀铬溶液中铜、铁和镍杂质的监控要求.     

沉淀分离-滴定法测定碱性锌镍合金镀液中的锌含量

在pH为4～6的条件下用丁二酮肟沉淀分离碱锌锌镍合金镀液中的镍离子,再用抗坏血酸掩蔽铁杂质,氟化钠掩蔽铝杂质,硫脲掩蔽铜杂质,在pH=5.4的条件下,以二甲酚橙作为指示剂,用EDTA标准溶液滴定锌。本法的相对平均偏差为0.35%,回收率为98.07%～99.32%,操作安全,无污染。     

二价镍和二价铁溶液中镍含量的测定

采用先氧化二价铁再加入掩蔽剂的方法，减少大量二价铁离子对测定镍的干扰，控制pH在8-9，温度在70～80℃的条件下，采用丁二酮肟沉淀重量法测定镍铁溶液中镍的含量。方法准确可靠，达到测定要求，值得推广。     

丁二酮肟比色法测定高比重合金中镍含量

本采用丁二酮肟比色法测定高比重合金中镍含量的实验条件是：溶液在碱性介质中，在氧化剂存在下，镍与丁二酮肟生成可溶性红色络合物，然后进行比色测定。     

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.     

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.     

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.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.