氧氟沙星的热稳定性及其热分解动力学

测定了在氮气气氛中第三代氟喹诺酮类药物氧氟沙星(OFLX)的热稳定性。用差示扫描量热法(DSC)、热重法(TG)和微分热重法(DTG),研究了药物氧氟沙星的热分解动力学。计算了动力学参数E、n、A,并结合量子有机化学计算的键长、原子静电荷参数研究了热分解机理,推断了热分解机理及药品贮存期。用热分析研究固体药物的热分解过程方法简便,结果可行。     

力醇罗热分解特性研究

采用差示扫描量热分析法（DSC）、热重分析法（TG）和微分热重法（DTG）,研究了力醇罗抗菌药的热分解动力学过程,计算了其热分解动力学参数一活化能（E）,分析了其热分解机理,并剖析了其结构特征。     

阻燃剂四溴苯酐的热分解动力学研究

用热重-差热分析法对阻燃剂四溴苯酐的热分解过程进行了动力学研究.结果表明四溴苯酐的热分解过程分两步进行.采用Dbyle-Ozawa积分法和Achar-Brindley-Sharp-Wendworth微分法对两步热分解过程分别进行分析,在30种机理函数中进行筛选,得到了四溴苯酐的两步热分解的最概然机理及动力学特性参数.     

甲基磺酸亚锡的热分析研究

用热重和示差扫描热分析法研究了甲基磺酸亚锡的热分解过程,其热分解过程分为三个阶段;在60～100℃脱水,在390～407℃甲基磺酸亚锡分解生成无机盐SnSO4;在407～425℃生成SnO.采用DTA-TGA技术研究了甲基磺酸亚锡在氮气中的非等温热分解机理及动力学. 根据TGA曲线确定了热分解过程中的中间产物及最终产物.运用Achar法和Coats-Redfern法对非等温动力学数据进行分析,得到热分解反应的机理函数和动力学参数.     

1-甲基-2,4-二硝基咪唑的合成及反应动力学

以4-硝基咪唑为原料,通过硝化、热重排、甲基化合成1-甲基-2,4-二硝基咪唑(2,4-MDNI),收率为87.2%,纯度不小于98%,并用红外光谱、核磁共振、元素分析等方法表征其结构。对其机理进行了假设,并通过动力学方法验证了反应机理。在动力学实验数据的基础上,计算了反应级数和反应速率常数,并计算出反应的活化能。研究了反应温度、反应时间等因素对合成及收率的影响,用正交试验得到了较优的工艺条件:2,4-二硝基咪唑、碘甲烷的摩尔比为5∶9,反应温度39~42℃,反应时间8h。用DSC研究了2,4-MDNI的热分解。     

炔雌醇甲醇溶剂化合物热分解非等温动力学研究

以炔雌醇为原料,甲醇为结晶溶剂,通过冷却结晶制备炔雌醇甲醇溶剂化合物,用差示量热扫描仪(DSC)、X-射线粉末衍射仪(XRPD)以及热重(TG)对结晶产物进行表征,采用非等温热重法对炔雌醇甲醇溶剂化合物热分解过程中溶剂热脱除过程进行了研究,通过最小偏差法判定得到炔雌醇甲醇溶剂化合物热分解过程的反应动力学机理函数。结果表明,炔雌醇甲醇溶剂化合物热分解过程分三个阶段,运用KAS模型分析了三个阶段热分解动力学数据,获得了三个阶段的热分解机理函数。     

炔雌醇甲醇溶剂化合物热分解非等温动力学研究

以炔雌醇为原料,甲醇为结晶溶剂,通过冷却结晶制备炔雌醇甲醇溶剂化合物,用差示量热扫描仪(DSC)、X-射线粉末衍射仪(XRPD)以及热重(TG)对结晶产物进行表征,采用非等温热重法对炔雌醇甲醇溶剂化合物热分解过程中溶剂热脱除过程进行了研究,通过最小偏差法判定得到炔雌醇甲醇溶剂化合物热分解过程的反应动力学机理函数。结果表明,炔雌醇甲醇溶剂化合物热分解过程分三个阶段,运用KAS模型分析了三个阶段热分解动力学数据,获得了三个阶段的热分解机理函数。     

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。     

基于热分析的亚油酸甲酯热解动力学研究

采用热重分析方法研究了亚油酸甲酯在氮气和氧气气氛中的热分解特性,并采用Coats-Redfern积分法对亚油酸甲酯的热解过程进行动力学分析,建立了热分解动力学模型,计算了相应的动力学参数。结果表明,亚油酸甲酯在两种气氛中的热分解均为两步分解过程,且在氧气气氛中的热安定性较差。随着升温速率提高,热解区间向高温区移动,热解活化能和指前因子呈较好的动力学补偿效应,且在不同升温速率下具有不同的热解反应机理函数。热分解率计算值与实测值的误差统计分析结果表明,数值模拟计算值与实测值的误差在10%左右,动力学模型可有效预测亚油酸甲酯的热分解过程。     

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.     

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。