相似放大理论在大型啮合同向旋转双螺杆挤出机设计中的应用

应用"当量直径"的方法,分析了在啮合同向旋转双螺杆挤出机内高聚物融体热传递相似、混合相似和剪切相似(Maddock)的条件,得到了3组主要性能参数相似放大的关联式.用此关联式对两类大型啮合同向旋转双螺杆挤出机系列的主要性能参数进行了预测,预测结果与实际较为吻合.     

大型同向旋转双螺杆挤压造粒机的相似放大理论

借鉴单螺杆挤出机相似放大理论,应用"当量直径"的方法,对9种典型相似放大方法进行了综合评价.基于CW&P公司ZSK Mc系列大型机的设计特点和技术数据,分析了相似放大方法在实际中的应用,提出了大型同向旋转双螺杆挤压造粒机的相似放大方法,宜采用螺杆线速度保持恒定的准则.     

从W＆P公司挤出机的两个设计指标看啮合同向双螺杆挤出机的发展趋势

从Ｗ＆Ｐ公司生产的双螺杆挤出的两个设计指标，作者讨论了啮合同向双螺杆挤出机的发展趋势，并建议发展浅槽型和深槽型两种同向双螺杆挤出机。     

同向双螺杆挤出机的应用及发展

本文简述了同向双螺杆挤出机的积木式设计原理及其应用，并介绍了科亚公司９９年新一代同向双螺杆挤出机的特点。     

同向双螺杆挤出机的应用及发展

本文简述了同向双螺杆挤出机的积木式设计原理及其应用，并介绍了科亚公司99年新一代同向双螺杆挤出机的特点。     

同向双螺杆挤出机在聚合物脱挥中的应用研究

综述了聚合物脱挥设备的分类和基本情况,并着重介绍了双螺杆挤出机在聚合物脱挥领域中的应用、优点、国内外发展概况及发展趋势等,同时在大量工业化应用的基础上提出了切实可行的同向双螺杆挤出机脱挥工艺,并详细分析了同向双螺杆挤出机主要零部件的设计要求和设计方法。     

双螺杆挤出机的分析和实验评述

双螺杆挤出机可按其几何结构进行分类,主要区别在于啮合和非啮合,另一个特点是回转方向,本文研究了各种双螺杆挤出机的最重要特性,特别把研究重点放在螺杆几何形状对输送特性的影响上;简短回顾了双螺杆挤出机理论分析方面的技术现状:描述了用两种实验室规格的啮合双螺杆挤出机进行的实验,一台是同向旋转双螺杆挤出机,另一台是异向旋转双螺杆挤出机,实验结果用两台挤出机的功耗,停留时间分布和混合性能给出,异向双螺杆挤出机呈现出窄的停留时间分布和较好的分散混合能力。同向双螺杆挤出机表明有较好的分布混合能力,这些结果可用两种挤出机中的输送和混合机理加以解释。挤出机的总体性能似乎受啮合区作用的支配。任何关于双螺杆挤出机的符合实际的理论分析应当集中在啮合区的流动行为和混合性能上,同向双螺杆挤出机似乎最适于熔体的共混操作,而异向双螺杆挤出机似乎优先用于体固添加剂必须分散到聚合物基体中的操作。     

新型橡胶螺杆挤出机及其应用

介绍橡胶工业新型螺杆挤出机的结构和应用范围。广泛应用的新型橡胶挤出机有同向双螺杆挤出机、异向双螺杆挤出机、多螺杆挤出机和行星挤出机等。同向双螺杆挤出机主要用于物理改性如共混、填充、纤维增强等；异向双螺杆挤出机主要用于挤出成型；多螺杆挤出机主要用于连续橡胶混炼，行星挤出机则更易控制加工温度。     

专业生产同向平行积木式双螺杆配件

南京力迅橡塑机械配件厂是一家专业从事同向平行积木式双螺杆挤出机零件的开发、设计和制造的综合型企业。公司的产品已经得到多个国家制造和使用同向平行积木式双螺杆挤出机客商的使用及认可。     

锥形双螺杆挤出机的模拟放大

介绍了用模拟放大定律来设计放大锥形双螺杆挤出机.分别用相似能量、性质、螺杆的动力消耗,压实理论来设计计量段、排气段、节流段和加料段.     

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。