煤中低分子化合物酮的氧化机理

煤反应机理的研究成为煤科学领域的热点和重要的研究内容。运用量子化学B3LYP方法,在6-311++g(d,p)基组水平上研究煤中低分子化合物丁酮的氧化机理,优化得到了反应途径上反应物过渡态和产物的几何构型。研究结果表明:丁酮的氧化机理有3种反应机制,其中丁酮低温氧化过程的最佳反应途径为O自由基进攻其官能团R基。关于醛类化合物的氧化机理我们将在稍后的研究中报道。     

Cl原子与CH_3COCH_3抽提反应机理的密度泛函理论研究

QCISD(T)/6-311++G(d,p)//B3LYP/6-31G(d,p)双理论方法研究了Cl原子与CH3COCH3的抽提反应过程。该反应包括两个反应通道:即Cl原子从CH3COCH3上直接抽氢(R1)和抽取CH3基团(R2)。在B3LYP/6-31G(d,p)水平上优化了反应物、产物、过渡态的几何构型,并作了最小能量路径分析,计算了反应的焓值和反应势垒,结果表明R1势垒比R2势垒低109.48 kJ/mol,说明反应R1是主反应通道。     

超临界水氧化丙烯氰废水的反应动力学理论研究

以丙烯氰为研究对象,探讨丙烯氰在超临界水氧化中的动力学研究。采用密度泛函理论研究氧负离子自由基与丙烯氰分子的反应。针对可能存在的抽氢反应、置换氢反应、生成水反应及羟基化反应通道,在B3LYP/6-311++G(2d,p)和HandHLY/6-311++G**的水平上得到反应物、产物、中间体复合物和过渡态的优化构型,并利用IRC计算证实反应通道。     

H与CH_2OH自由基反应机理的理论研究

利用量子化学计算方法,采用密度泛函理论(DFT)研究了H与CH_2OH自由基反应的机理。在6-311++G**基组水平上,优化得到了反应途径上的反应物、过渡态、中间体和产物的几何构型;在B3LYP/6-311++G**优化的构型基础上,采用CCSD(T)/aug-cc-pvtz方法对所有的驻点及部分选择点进行了单点能校正,并得到各驻点的高级单点能量;通过振动分析对过渡态和中间体构型进行了确认。计算结果表明:H与CH_2OH自由基的反应有两种不同的反应机制。其中,H原子加成到CH_2OH自由基中O4原子上消去H2的反应是主反应通道,P1(CH_2O+H_2)为主要产物。     

Cl原子与CH3COCH3抽氢反应的动力学研究

采用QCISD(T)/6-311++G(d,p)//B3LYP/6-31G(d,p)双理论方法研究了Cl原子与CH3COCH3的抽氢反应过程.在B3LYP/6-31G(d,p)水平上优化了反应物、产物、过渡态的几何构型,并作了最小能量路径分析.在从头算的基础上,用变分过渡态理论加小曲率隧道效应方法计算200～2500 ...     

大黄素和大黄素甲醚抗氧化活性的密度泛函理论研究

本文采用密度泛函理论(DFT)方法,在B3LYP/6-311G(d,p)水平下对气相和溶剂中大黄素和大黄素甲醚及其可能解离途径中形成的自由基进行结构优化,在结构优化的基础上用B3LYP/6-311++G(2 d,2 p)基组计算了其相应的单点能,通过三种抗氧化反应机制、清除·OOH自由基的机理等方面分析了分子活性位与其性质的关系,分析了两种物质酚羟基在不同环境中抗氧化活性的能力大小。计算结果表明,大黄素和大黄素甲醚分子分别在C3和C8位上酚羟基活性最高,是最大可能的活性位点,大黄素的酚羟基活性略高于大黄素甲醚。在气相中氢原子转移是主要的机制,在极性溶剂中单电子转移是主要机制,在非极性溶剂中连续的质子损失电子转移是主要机制。     

CH3SH与CN自由基反应的理论研究

在MP2／6—311G（d,p）水平上研究了CH3SH与CN自由基反应的机理,优化了所有驻点的几何构型,并进行了振动频率分析。用双水平方法G3MP2／／MP2／6—311G（d,p）构建了反应势能面。用RRKM理论计算了200-1000K温度范围内的速率常数,计算值与实验值符合较好。结果表明：CN自由基中的C抽取一SH上的H是主要反应通道,CH。S和HCN是主要反应产物。     

黄酮类化合物槲皮素光谱特性研究

采用密度泛函理论B3LYP算法,在6-311＋＋G（d,p）基组对槲皮素进行构型优化,经频率矫正后,对槲皮素紫外及红外光谱进行模拟计算,分析了槲皮素紫外光谱特征的结构因素,并通过实验数据进行验证。     

偏二甲基肼亲核性的量子化学研究

为了从分子水平上了解偏二甲基肼(UDMH)中-NH2和-N(CH3)2的亲核性差异,采用RHF、DFT/B3LYP、MP2及半经验量子化学方法对UDMH进行了几何构型全优化,并将计算的平衡几何结构参数与实验值进行了对比.在B3LYP/6-311G计算所得的平衡几何构型基础上,分别根据静电势和分子轨道计算研究了分子中-NH2和-N(CH3)2的亲核性,并与偏二甲基肼和卤代烃反应的实验结果进行了对比分析.结果表明,分子轨道计算的亲核性结果与实验结果一致,表明-N(CH3)2比-NH2具有更强的亲核性.     

偏二甲基肼亲核性的量子化学研究

为了从分子水平上了解偏二甲基肼（uDMH）中-NHz和-N（CH3）2的亲核性差异，采用RHF、DFT／B3LYP、MP2及半经验量子化学方法对UDMH进行了几何构型全优化，并将计算的平衡几何结构参数与实验值进行了对比。在B3LYP／6—311G计算所得的平衡几何构型基础上，分别根据静电势和分子轨道计算研究了分子中-NH2和-N（CH3）2的亲核性，并与偏二甲基肼和卤代烃反应的实验结果进行了对比分析。结果表明，分子轨道计算的亲核性结果与实验结果一致，表明-N（CH3）2比-NH2具有更强的亲核性。     

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.     

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.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008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、不饱和聚酯树脂、环氧树脂)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.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006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生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。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（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。