新的液相扩散系数模型

根据统计力学理论与Eyring绝对速率理论,建立了描述液相扩散系数的理论模型。该模型反映了温度、压力及组成对液相扩散系数的影响。基于此模型,建立了关联高压液相自扩散系数与密度关系的模型方程;导出了二元溶液相互扩散系数与浓度关系的计算方程;建立了计算无限稀释扩散系数的方程。通过对实际物系的验证计算,本文所导出的各方程均能很好地关联计算液相扩散系数,并优于文献方程。     

非电解质溶液扩散系数的理论研究评述

许多过程都涉及扩散控制的传质,相应的扩散速率计算对过程工程的精确量化具有重要意义.本文简述了扩散速率的理论表述模型,并着重介绍了非电解质溶液内扩散系数的理论分析计算途径.分子动力学模拟正处于发展中,并用于估算自扩散系数,但进入实用化阶段尚需时日,唯象模型仍为最重要的理论计算手段.作为最常用的方法,由无限稀释浓度下的扩散系数以及合适的插值方法可计算特定浓度下的扩散系数;自由体积理论是半经验性模型,可以计算自扩散系数,并借助混合规则计算相互扩散系数;最后,对扩散系数的理论研究作了展望.     

含醇溶液中分子扩散系数的分子模拟

利用分子动力学(MD)模拟验证了含醇溶液的无限稀释扩散系数模型和不同浓度溶液的扩散系数模型.选用的溶质分别为甲醇、乙醇、丙醇、异丙醇、正丁醇和甘油,温度为293.15K,压力为0.1MPa.计算结果表明:Dullien和Asfour方程适用于计算甲醇和乙醇溶液的扩散系数DAB;而对于其它醇溶液的扩散系数,Leffler和Cullinan方程较适用.     

离子液体［BMIM］Br的水溶液VLE与扩散系数的分子模拟

在Linux操作系统下采用Towhee软件和NPT-Gibbs系综Monte-Carlo方法（GEMC）,模拟了不同温度、不同压力下二元体系［BMIM］Br+H₂O的汽液相平衡性质。提出了一种修正介电常数的方法来计算长程力,所得结果与非极化模型、极化模型及实验结果进行了比较。结果表明：相比于极化模型和非极化模型,修正介电常数的计算结果更接近实验值。此外,采用DL_POLY软件和分子动力学模拟的方法对［BMIM］Br水溶液的扩散系数进行了计算。结果表明：随着溶液中水含量的增多,ILs阴阳离子以及水分子的扩散系数得到了明显的改善。     

葡萄糖水溶液扩散系数的测定与关联

液相扩散系数在化工数据中起着非常重要的作用,由于液体结构及扩散本身的复杂性,至今还没有一个合理的理论模型来预测液相扩散系数,有必要从实验和理论上对不同的体系进行研究.制备了金属膜池,用氯化钾溶液标定了膜池常数,并用已有可靠文献值的蔗糖水溶液验证了装置的可靠性.测定了298.15～328.15 K不同温度下葡萄糖水溶液的积分扩散系数,考察了温度对扩散系数的影响.在实验数据的基础上,提出一个有温度关联项的半经验模型,关联和计算了本实验的数据,结果与实验值吻合很好.     

数字全息干涉法测量二元溶液互扩散系数

由一维无限长扩散模型入手,建立了探测光相位与液体互扩散系数之间的数学模型,进而在现有数字全息干涉法的基础上,提出了一种新型的二元液体互扩散系数测量方法。由于该方法直接利用探测光相位求取互扩散系数,因此可有效避免外界噪声信号对实验结果的影响,从而降低了数字全息干涉法对外界光学环境的要求。该方法的互扩散系数测量相对合成不确定度为0.7%。测量了25℃下、0.33 mol/L KCl水溶液的互扩散系数,实验结果与文献值符合良好,验证了该测量方法的可行性。利用该方法,测量了甲醇/环己烷二元系在其不互溶区附近的互扩散系数,揭示了其在该区域的变化规律。依据实验数据,预测了该二元系的热力学亚稳定和非稳定区域的分界线--Spinodal曲线。     

1:1对称型单独电解质溶液扩散系数数学模型的研究

提出了缔合式电解质溶液的扩散理论,和计算1∶1对称型单独电解质溶液扩散系数的数学模型。 用该式对KCl等十四种电解质溶液的扩散系数进行了计算,计算值同文献值的吻合程度,比罗宾逊-斯托克斯模型的计算结果有显著的改善。 在常压、25℃下,又对KCl溶液的扩散系数进行了测定,结果表明实测值同本数模计算值吻合程度令人满意。     

数字全息干涉法测量二元溶液互扩散系数

由一维无限长扩散模型入手,建立了探测光相位与液体互扩散系数之间的数学模型,进而在现有数字全息干涉法的基础上,提出了一种新型的二元液体互扩散系数测量方法。由于该方法直接利用探测光相位求取互扩散系数,因此可有效避免外界噪声信号对实验结果的影响,从而降低了数字全息干涉法对外界光学环境的要求。该方法的互扩散系数测量相对合成不确定度为0.7%。测量了25℃下、0.33 mol/L KCl水溶液的互扩散系数,实验结果与文献值符合良好,验证了该测量方法的可行性。利用该方法,测量了甲醇/环己烷二元系在其不互溶区附近的互扩散系数,揭示了其在该区域的变化规律。依据实验数据,预测了该二元系的热力学亚稳定和非稳定区域的分界线——Spinodal曲线。     

混合电解质溶液在多孔颗粒内扩散的数学模型

建立了混合电解质溶液在多孔颗粒内扩散的数学模型,并由此计算了交互扩散效应的大小;讨论了单一扩散系数的菲克定律描述电解质混合物扩散的适用性;用模型处理了HCl-KCl-H_2O体系的实验数据,得出了有效主扩散系数和有效交互扩散系数.     

二元溶液气液相平衡实验物系选择的探索

本文讨论了二元溶液气液相平衡实验中物系的选择问题.经过实验研究及分析讨论,结果表明采用正丙醇-水二元溶液物系,利用折光法测定气液相摩尔组成进行二元溶液相平衡实验是合适的.由该物系的实验数据关联得到的模型方程参数与Van Laar方程的文献值吻合较好.另外,正丙醇-水二元体系毒性小,价格便宜,适合高校化工热力学与化工原理教学实验使用.     

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.     

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.     

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。     

ICP-MS法测定地球化学样品中As、Cr、Ge、V等18种微量痕量元素的研究

建立了测定地球化学样品中包括As、Cr、Ge、V等18种微量、痕量元素的ICP-MS方法。地化试样用HF-HNO3混酸分解后,以1 1 HNO3溶解干渣。由于制样不使用盐酸,避免了Cl对As、Cr、Ge、V的质谱干扰。用国家一级地球化学标准物质GBW 07309制备溶液优化仪器工作参数,并用于校准。方法测定限(6s)为:0.007~6.4μg/g,精密度(RSD%,n=12)为:29%~9.4%,经过国家一级地球化学标准物质的分析验证,结果与标准值吻合。方法已应用于国土资源调查的试样分析。