固体可逆接触式微型玻璃电极的成分与性能

体可逆接触式玻璃电极以固体合金代替溶液，可解决常用的液体接触式玻璃电极安全性问题，而且易于微型化。本文研究了固体可逆接触式玻璃电极敏感玻璃所用Li2O—La2O3—Ta2O5—SiO2系统成分及物理化学性质，用La2O3代SiO2对玻璃析晶、软化点、膨胀系数、耐水性和电导率的影响。用所研究成分制成的微型玻璃电极在pH1～7间转换系数96％以上，与pH值对应的响应电势E呈直线关系，有较好的氢离子选择功能，滞后误差小，测定数据的重复性也较好，符合医用微型玻璃电极的性能要求。     

玻璃电极

§1 应用玻璃电极测量pH值的基本方法图(1)中的玻璃容器中部,熔有以特殊玻璃制成的薄膜,薄膜两侧注有不同pH值的溶液,其中并浸有同式的甘汞电极。将二甘汞电极与高度灵敏的测量仪器联接,即可测得两端间有确定的电位差存在,且这电位差随两侧溶液pH的差别而变化。这只能解释为在玻璃薄膜两侧与     

锑电极自动调节pH

锑电极作pH发讯器的过程及效果,并对洗涤剂中和pH值实现了自动调节,从而改善了人工调节pH值给产品质量和工艺设备带来的一系列缺陷。本文权衡了玻璃电极和锑电极的优缺点。根据控制洗涤剂中和pH值的要求和条件,选用锑电极作pH发讯元件进行试验。用浇铸法将纯度为99.5％的锑粉制成pH电极,考虑到被测介质对电极的污染,将锑加工成锑环,设计了机械清洗装置。此电极与甘汞电极构成的发讯系统,其pH-毫伏特性曲线比较理想,转换系数为55毫伏/pH,量程为pH2～12近似直线,精度为pH±0.2。采用XWDI系列小型自动电子电位差计记录指示     

pH与电位连续测定

当一金属插入含有该金属离子的溶液中时,则在金属与溶液之间就会产生电位差。这一电位差称为电极电位。其值之大小,为溶液中离子浓度的函数。因此,通过电极电位的测定,可以计算出溶液中离子的浓度。这种以测定电极电位为基础的分析方法,称为电位测定法。其中包括一般的电位测定与pH的电位测定。由于这一方法比较准确,而且操作简便,因此,在化工生产过程中经常使用,如对某些反应条件的控制(如溶液的pH值与反应物质的浓度等),对中间产品和最后成品质量的连续测定等等。     

氢氧化钠沉淀法制备氧化铋粉末的研究

对氢氧化钠沉淀法直接制备Bi2O3粉末进行了研究，实验发现反应温度、终点pH值和搅拌强度对Bi2O3的纯度有较大的影响，研究表明：最佳工艺条件为反应温度70～90℃，pH值12左右，搅拌速度约300r/min，制得的Bi2O3为β型、针状、粒度为1～10μm、高纯度的粉末，可应用于对粒度和纯度有一定要求的无机颜料，阻燃剂、抑烟剂、高折光玻璃和核工程玻璃等领域。     

氢氧化钠沉淀沽制备Bi2O3粉末的研究

对氢氧化钠沉淀法制备Bi2O3粉末进行了详细的研究,大量探索实验发现,反应温度、终点pH值和搅拌速度对Bi2O3的纯度有较大的影响。研究表明,最佳工艺条件控制为反应温度70－90℃,pH值12左右,搅拌速度约300r/min时,制得的Bi2O3为β型、针状、粒度为1－10μm的高纯度粉末。该粉末用于对粒度和纯度有一定要求的无机颜料、阻燃剂、抑烟剂、高折光玻璃和核工程玻璃等领域。     

气敏电极法测定离子膜制碱工艺二次盐水中的氨

研究了用气敏电极测定离子膜制碱工艺二次盐水中氨的分析方法 ,对测定的线性范围作了理论探讨和大量试验 ,pH值为 10 .5～ 11.5时 ,线性范围为 0 .15～ 8.0mg/L ,最低检出限度为 0 .0 85mg/L ,RSD不大于1.5 %     

P~(Na)变形零点电位法测定玻璃中Na_2O的含量

P~(Na)电极电位法是用由特种成分的玻璃电极测定水溶液中Na~+离子含量的一种新方法。P~(Na)电极和p~H电极一样,它们都是选择性离子敏感电极。当它们各与参比电极浸入测试液而构成原电池时,该原电池所产生的电动势大小主要决定于溶液中被测Na~+或H~+离子的活度。如果用高阻抗电位差计测得上     

物理打磨对玻碳电极性能影响的研究

在应用于电化学研究时,玻碳电极需要在每次实验前进行预处理,以改善其电化学响应的重现性,打磨程度对化学响应有不同的影响。分别使用1000～5000目的金相砂纸和Al_2O_3抛光粉对玻碳电极直径分别为3、4、5 mm的电极进行物理砂磨预处理,然后在0.2 M KCl和1 mM K_3Fe(CN)_6溶液中测试其循环伏安,进一步研究了研磨程度(次数)对玻碳电极的电极性能存在的影响。实验结果表明:电极打磨得越精细玻碳电极的峰电位差越接近可实验值(△φ=80～90 mV);活化后的玻碳电极较于活化前其电极的峰电位差更接近理论值(△φ=64 mV)。     

B_2O_3-P_2O_5-ZnO系统玻璃密度与结构关系研究

采用传统熔融冷却法制备了B2O3～P2O5-ZnO系统玻璃,运用IR和Raman光谱等手段分析了B2O3含量对玻璃结构的影响,并用密度和摩尔体积对上述结构进行验证。结果表明：对于B2O3-P2O5-ZnO系统玻璃,随R值增大,其IR和Raman光谱呈现出规律变化。IR光谱申,在～1423cm^-1处出现一个新吸收带,它对应[EO3]中B-O键的对称伸缩振动vs（B-O）。相应地,Raman光谱中的～520cm^-1和～1050cm^-1处出现新的散射峰,并随R值增大,其强度明显变大。密度和摩尔体积对R值也很敏感,随R值增大,密度线性增加,摩尔体积线性减小,二者都在R=0．333处达到极值。因此对该系统玻璃来说,可以利用玻璃的密度值对其结构进行预测。     

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.     

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.     

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。