轮胎胶料口模挤出胀大与入口弹性贮能的关系

考察了洞口胶和缓冲胶在毛细管挤出流动中的粘弹性行为及机理。在温度为90℃和表现剪切速率为10－10^3s^-1的操作条件下，2种轮胎胶料的剪切流动均服从幂律，且非牛顿指数值相差不大；入口压力降（△Pen)，入口弹性贮能（e)和口模膨胀比（B）均随着剪切应力的增加而呈线性函数形式增大。在相同的挤出条件下，洞口胶的B值高于缓冲胶；而△Pen则相反。B与e之间呈线性函数关系。     

ABS熔体挤出流变性质的研究

考察了毛细管挤出过程中温度和流动速率对ABS树脂熔体流变行为的影响。结果表明 ,当剪切速率大于 10 3s 1后 ,熔体的剪切流动不服从幂律 ;而剪切粘度对温度的依赖性符合Arrhenius方程 ;入口压力降和入口拉伸应力均随着剪切应力的增加而呈非线性函数形式增大     

内胎胶料的挤出胀大行为

用Monsanto毛细管流变仪,在100～130 ℃及流动速率1.02～254.00 mm/min的条件下,考察了内胎胶料的挤出胀大行为.结果表明,在一定温度下,挤出胀大比(B)随着壁面表观剪切速率的增加而增大,两者之间呈非线性函数关系,而B与壁面剪切应力则大致上呈线性函数关系;当表观剪切速率一定时,B随着温度的升高而非线性下降.在一定的挤出条件下,B随着流道直径比的增加而有所增大,两者之间近似呈线性函数关系.     

POE/纳米碳酸钙复合材料的流变性能研究

试验研究聚烯烃弹性体（POE）／纳米碳酸钙复合材料的流变性能。结果表明，随着剪切速率的增大，复合材料的剪切粘度和非牛顿指数逐渐减小，挤出胀大比和零口型入口压力降增大，挤出物外观变差；随着纳米碳酸钙用量的增大，复合材料的剪切粘度对剪切速率的敏感性下降，非牛顿指数增大，挤出胀大比总体上呈下降趋势，零口型入口压力降变化较小，在相对低的剪切速率下，挤出物外观得到改善。     

含有防老剂未硫化天然胶挤出中的弹性行为

引用文献发表的实验数据,研究了含有防老剂未硫化天然胶胶料毛细管挤出过程中的弹性行为。发现,在实验条件下,试样的Bagley校正因子e和挤出胀大比B均随表观剪切速率增加而增大,且呈某种指数形式:而e和B之间则大体上成线性关系。     

短玻纤增强聚丙烯材料流变性能

利用双料筒毛细管流变仪,测得不同玻纤含量的短玻纤增强聚丙烯材料在不同剪切速率下不同长径比口模的压力降。对比Bagley校正法及零口模校正法得到的入口压力降之间的差别,研究玻纤含量、剪切速率对入口压力降、非牛顿指数及表观剪切黏度等流变参数的影响。结果表明:与Bagley校正法相比,零口模校正法更加可靠;短玻纤增强聚丙烯材料属于假塑性流体,存在剪切变稀行为;随玻纤含量增高,所测得的入口压力降增大,计算得到的熔体的表观剪切黏度也增大,熔体的非牛顿指数降低。     

高挤出速率下LDPE熔体流动特性的研究

应用Ｒｏｓａｎｄ毛细管流变仪,于高挤出速率下考察了低密度聚乙烯熔体的流动特性。发现：熔体的剪切流动大体上服从幂定律;入口压力降剪切速率或剪切应力的增加而呈非线性函数形式增大;熔体的剪切粘度对温度的依赖性符合Ａｒｒｈｅｎｉｕｓ关系,其温粘性随着剪切强度的增加而有所减弱,此外,当前切速率大于４００ｓ＾－１时可观察到流动曲线的“平台”现象。     

内胎胶挤出流动中出口压力降的估算

应用前文中提出的出口压力降△exit与挤出胀大比的关系式,估算了挤出条件下内胎胶的出口压力损失。结果表明,当温度一定时,△exit随着剪切速率的增加而增大;而在固定的剪切速率下,△exit则随着温度的升高而下降。     

EPDM/PP热塑性弹性体的制备及其流变特性

以聚丙烯(PP)和三元乙丙橡胶(EPDM)等为原料,采用完全动态硫化共混技术制备EPDM/PP热塑性弹性体(TPV),使用毛细管流变仪对TPV熔体的流变特性进行测试。分别研究了剪切速率、挤出温度对黏度、剪切应力和挤出胀大比的影响,以及不同条件下熔体流过毛细管口模时流速对压力降的影响。结果表明,TPV熔体是假塑性流体,其剪切应力随剪切速率增大而增大,随挤出温度的升高而降低;黏度随剪切速率和挤出温度的增大而降低;挤出胀大比则随剪切速率和挤出温度的增大而增大;毛细管口模的压力降也随流速和毛细管口模长度的增大而增大。     

停放时间对炭黑填充溶聚丁苯橡胶/顺丁橡胶并用胶挤出流变特性的影响

研究停放时间对炭黑填充溶聚丁苯橡胶(SSBR)/顺丁橡胶(BR)并用胶挤出流变特性的影响。结果表明:结合胶质量分数、应力松弛时间和门尼粘度均随停放时间的延长而增大,且变化规律相似;混炼胶的Payne效应和储能模量均随停放时间的延长而增大,表明炭黑聚集体在混炼胶停放过程中出现一定程度团聚;混炼胶的挤出粘度随着停放时间的延长略有增大;入口压力降随着停放时间的延长显著增大,且温度的影响较为明显;停放48 h后,混炼胶的挤出物均出现较为明显的锯齿形瑕疵,停放24 h混炼胶的挤出胀大比最小。对炭黑填充SSBR/BR并用胶体系而言,其最佳的停放时间为24 h。     

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.     

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。     

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.