药用合成聚异戊二烯透明垫片性能研究

研究了药用合成聚异戊二烯透明垫片的理化和生物性能,结果表明,其性能优于目前使用的药用合成聚异戊二烯垫片,其中化学和生物性能尤为突出,是未来药用合成聚异戊二烯垫片的发展趋势。     

单甲基丙烯酸锌对氢化丁腈橡胶复合材料性能的影响

以单甲基丙烯酸锌(ZMMA)为补强剂,采用机械混炼法制备ZMMA/氢化丁腈橡胶(HNBR)纳米复合材料,研究ZMMA对HNBR复合材料结构和性能的影响。结果表明:随着ZMMA用量的增大,复合材料的t10和t90均呈缩短趋势,交联密度逐渐增大,100%定伸应力和撕裂强度增大,拉断伸长率呈减小趋势。当ZMMA用量为30份时,HNBR复合材料的拉伸强度出现最大值。ZMMA均聚物的存在导致材料的最大分解速率温度和玻璃化温度向高温方向移动,提高了HNBR复合材料的热稳定性。     

单甲基丙烯酸锌对HNBR复合材料的增强行为研究

以单甲基丙烯酸锌作为补强剂,采用机械混炼法制备了ZMMA/HNBR纳米复合材料,研究了单甲基丙烯酸锌对氢化丁腈橡胶的补强效果,用热失重分析(TG)、差失扫描热量分析(DSC)及材料拉力机等测试方法对复合材料的结构和性能进行了表征测试。实验结果表明,随着ZMMA用量的增加,复合材料的焦烧时间和正硫化时间均呈减少趋势,橡胶复合材料的交联密度逐渐增加,与高分子拉伸取向行为关联不大100%定伸强度和撕裂强度均增加,扯断伸长率呈单调降低。当ZMMA用量为30 phr时,HNBR复合材料的拉伸强度出现最大值。同时,ZMMA聚合物的存在导致材料的最快分解温度和玻璃化转变温度向高温移动,提高了HNBR复合材料的热稳定性。     

甲基丙烯酸锌增强氢化丁腈橡胶复合材料的性能

采用甲基丙烯酸锌(ZMMA)为增强剂填充氢化丁腈橡胶(HNBR),研究了ZMMA用量对ZMMA/HNBR复合材料硫化特性、力学性能、热稳定性以及玻璃化转变温度(Tg)的影响。结果表明,随着ZMMA用量的增加,复合材料的焦烧时间和正硫化时间缩短,最大转矩和交联密度提高;复合材料的拉伸强度先升高后下降,撕裂强度和100%定伸应力增大,而扯断伸长率降低。复合材料的Tg随着ZMMA用量的增加逐渐升高;ZMMA的加入提高了复合材料的热稳定性。     

SIS增容改性TPI/CR并用胶的性能研究

研究了嵌段共聚物SIS(苯乙烯-异戊二烯-苯乙烯)的不同用量对TPI(反式聚异戊二烯)/CR(氯丁橡胶)共混体系性能的影响。结果表明,适量加入嵌段共聚物SIS可以有效改善共混体系的相容性,缩短并用胶的正硫化时间,增大并用胶的拉伸强度、撕裂强度,同时,还可提高并用胶的电绝缘性能。     

甜菜碱对聚异戊二烯橡胶性能的影响简

探讨甜菜碱(三甲铵乙内酯,天然橡胶非胶组分)对聚异戊二烯橡胶(IR)硫化特性、强伸性能和热稳定性能的影响。结果表明:与未加甜菜碱的IR相比,添加甜菜碱的IR硫化速度显著提高,交联密度增大,强伸性能改善,热稳定性能略有提高;当甜菜碱用量为0.5份时,IR的综合性能最佳。     

硫化时间对HNBR/ZMMA复合材料形态结构及性能的影响

采用炭黑和单甲基丙烯酸锌(ZMMA)并用作补强剂制备了氢化丁腈橡胶(HNBR)复合材料,使用X射线衍射法和透射电子显微镜法分析了ZMMA在HNBR硫化过程中的结构和形态变化,并研究了一段硫化时间对复合材料力学性能的影响。结果表明,在硫化过程中,ZMMA发生了复杂的化学反应;随着一段硫化时间的延长,氢化丁腈橡胶复合材料的拉伸强度和100%定伸应力变化都不大,而撕裂强度先增大后减小,拉断伸长率减小。X射线衍射结果表明,ZMMA由结晶态转变为非结晶态。透射电子显微镜分析结果表明,在硫化开始阶段,ZMMA聚合反应已经完成,有大量的纳米级粒子分布在橡胶基体中。     

EPDM/TPI并用胶性能研究

研究了反式-1,4-聚异戊二烯(TPI)不同用量对三元乙丙橡胶(EPDM)/TPI并用胶力学性能和动态屈挠性能的影响。结果表明,在EPDM/TPI并用比为70/30时,并用胶在力学性能改善的基础上,动态屈挠性能得到显著提高。     

水性聚氨酯压敏胶耐热性能的研究

本文以端羟基氢化液态聚异戊二烯橡胶(HLBH2000)为改进剂,对水性聚氨酯压敏胶进行改性研究。结果表明,当异氰酸酯指数(R值)为1.05,物质中硬段结构与软段结构的摩尔数之比(C/A值)为3.5,氢化液态聚异戊二烯橡胶用量为7.5%时,可以得到性能优异的聚氨酯水性压敏胶。     

负载型钒系TPI/SSBR并用胶性能的研究

研究了负载型钒系反式-1,4-聚异戊二烯(TPI)不同用量对TPI/溶聚丁苯橡胶(SSBR)并用胶物理性能和动态性能的影响。结果表明,随着TPI含量的增加,并用胶的焦烧时间延长,拉伸强度、拉断伸长率以及耐热空气老化性能都得到提高。同时,加入TPI还可减小并用胶的滚动阻力和改善生热状况。     

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.     

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.     

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。