聚对苯二甲酸丁二醇酯的热分解动力学研究

通过热重分析(TGA)法研究了聚对苯二甲酸丁二醇酯(PBT)在氮气气氛中不同升温速率下的热分解过程,采用不同的动力学数据处理方法研究了PBT的热分解机理。结果表明:采用Kissinger法、FlynnWall-Ozawa法和Friedman法计算PBT的热分解反应活化能分别为179.93,175.83,161.07 kJ/mol,平均值为172.28 kJ/mol,与Coast-Redfern法计算的活化能180.41 kJ/mol接近,取PBT热分解反应活化能为180.41kJ/mol,计算得指前因子为2.68×10~(10)s~(-1);采用Coast-Redfern法和Criado法研究了PBT的固相热分解反应机理,认为PBT的热分解机理属于相边界控制的收缩圆柱体反应机理,反应级数为0.5。     

FeS还原CaSO_4的热分解动力学研究

以热重(TG)分析为手段,研究了FeS还原CaSO_4在氮气气氛中的热分解动力学。利用KAS法、Ozawa法、KAS-迭代法和Ozawa-迭代法对其进行了动力学分析,求出了该反应的动力学参数,同时利用Coast-Redfern法研究了该反应的动力学机制函数。结果表明:N_2气氛下FeS还原CaSO_4的热分解机制符合相边界反应,其动力学方程为G(α)=1-(1-α)~(1/3),表观活化能为309.28 kJ/mol,表观指前因子为2.17×10~(11)s~(-1)。     

双酚A型聚芳醚酮的热分解动力学研究

用热重(TG)法研究了双酚A型聚芳醚酮(PAEK)的热分解动力学,计算了热分解动力学参数.结果表明,双酚A型PAEK的热分解符合无规引发分解模型,热分解过程为一级反应.以Kissinger最大失重率法求得热分解反应的反应活化能E为201.909kJ/mol;以Ozawa等失重百分率法求得反应活化能E为211.398kJ/mol;频率因子A值为2.306×10~(14)～9.173×10~(14)min~(-1);预测N_2中267℃失重5%的热老化寿命为10 a.     

农业废弃物葵花秆热解过程几种动力学模型结果比较

利用同步热重分析仪考察了不同升温速率下葵花秆的热失重行为并进一步研究了其热解特性,根据热重数据采用四种热分析动力学模型:Friedman法、Doyle法、Flynn-wall-Ozawa(F-WO)法和DEAM法研究了葵花秆的热分解动力学,估算出热解反应的表观活化能。结果表明:葵花秆的主要失重区间为200~400℃,随着升温速率的提高,葵花秆热解的初温度升高,热解向高温方向移动。同时四种方法获得的葵花秆活化能值分别为519.1kJ/mol,235.33kJ/mol,223.8kJ/mol和224.9kJ/mol。采用Friedman法得到的活化能值高于其它三种方法。葵花秆热解是包含了分子键能断裂的一系列复杂、连续反应过程。     

阿莫西林的热分解行为研究

利用热重分析（TG）采用不同升温速率（5,10,15,20,30℃/min）在氮气气氛下对阿莫西林热分解动力学进行了研究。采用Coats-Redfern和Ozawa热分析处理动力学数据的方法,计算阿莫西林热分解反应活化能E及指前因子A。结果表明,阿莫西林的热分解反应为一级反应,在15%～35%的失重率时热分解表观活化能为51.43～56.34 kJ/mol,指前因子lgA值为8.76～9.38。     

硫脲的热分析研究

在非等温条件下,改变升温速率对硫脲进行了热分解动力学方面的研究,并用微分Kissinger法和Ozawa法对硫脲的热重和热流曲线进行了动力学分析,得出硫脲热分解过程的动力学参数,硫脲异构化活化能为80 kJ/mol,硫氰酸胍生成反应的活化能为205 kJ/mol,实验结果与文献吻合。     

中低品位磷矿焙烧过程中白云石热分解动力学研究

通过对贵州某中低品位磷矿进行TG-DTG热分析实验,分析了磷矿焙烧过程磷矿中白云石的热分解历程,运用等转化率法和模式配合法相结合的方法,研究了磷矿中白云石的热分解动力学、计算了相关动力学参数、得出磷矿中白云石热分解动力学模型.结果表明,磷矿中白云石热分解分为两个阶段,第一阶段活化能为111.9 kJ/mol,遵循二维相界面反应;第二阶段活化能为176.9 kJ/mol,遵循三维扩散(Jander方程).基于研究结果,建立了白云石热分解过程每个阶段的动力学模型.     

2-巯基吡啶镉(Ⅱ)、汞(Ⅱ)配合物的热分解动力学研究

采用TG-DTG技术研究了2-巯基吡啶镉(Ⅱ)、汞(Ⅱ)配合物在氮气气氛中的热分解机理及非等温动力学。采用积分法(Coats-Refern方程,HM方程,MKN方程)和微分法(Achar方程)对非等温动力学数据进行了分析,得到了配合物第一步热分解反应的机理函数、动力学参数和热分解动力学方程。结果表明:其热分解过程属F2(化学反应)机理控制,非等温热分解的动力学方程为dα/dT=A/β.e-E/RT(1-α)2,其中镉(Ⅱ)配合物的表观活化能E=86.35 kJ/mol,指前因子A=4.72×107s-1;汞(Ⅱ)配合物的表观活化能E=189.67 kJ/mol,指前因子A=3.79×1018s-1。     

非等温热重法研究聚苯醚热分解动力学

采用非等温热重法对聚苯醚的热分解动力学进行研究,计算了反应活化能,采用积分法结合36种动力学函数来判断聚苯醚热分解的机理函数,得到了聚苯醚热动力学参数即反应的动力学函数,平均活化能（E_a）为211.64kJ/mol,指前因子（A）的平均值为6.24×10⁷s^-1,也获得了对应的热分解动力学方程。     

1-丁基-3-甲基咪唑四氟硼酸盐离子液体的热分解动力学研究

利用非等温热重分析法(TG),研究了高纯氮气气氛下1-丁基-3-甲基咪唑四氟硼酸盐([bmim][BF4])的热分解动力学及机理函数。采用等转化率法和多元非线性回归法测定了[bmim][BF4]的热分解动力学。等转化率法表明[bmim][BF4]的活化能为E和指前因子logA分别为:198 kJ/mol和11.94 s-1。多元非线性回归法表明[bmim][BF4]的热分解机理模型函数为:n级自催化反应(Cn),反应级数为n=1.1426,所对应的机理模型函数为fα=1-α1.14261+1.0024α,指前因子logA和活化能E分别11.18 s-1和188 kJ/mol。另外,等转化率法和多元非线性回归法测得的活化能与量子化学计算法得到的活化能值均相吻合。     

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.     

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.     

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。     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.