超细粉体的应用及制备

介绍了超细粉体在国民经济各领域的应用,研究了各种超细粉体的制备技术,分级技术及设备的性能特点,分析了国内外相关技术,对超细粉体技术今后的发展和研究方向提出了建议。     

超细粉体分级技术现状及进展

本文首先综述了国内外超细粉体分级技术现状及进展，进而讨论了超细粉体分级技术中存在的难题，认为影响分级效果的关键因素之一是超细粉体的分散性；另一关键因素是粒子在不同状况下运动特性。如果提高超细粉体的分散性，按照粒子的运动特性设计出合理的分级力场，将有助于提高分级级效果。     

冻干超细粉体技术生产超细鲜骨粉

冷冻干燥超细粉体技术是20世纪80年代后期基于冷冻干燥技术与超细粉体技术发展起来的一项跨学科、跨行业的高新技术。     

粉体的超细磨

超细粉体技术是当今世界上很重要的科学技术之一。我国在这方面的研究起步较晚，只是近十几年才得到重视和发展。本文比较系统地介绍了超细粉体技术的发展、应用以及产品的制备等情况，对超细粉体的加工方法作了系统的比较，特别是对价格低档次工业生产产品制备方法居多的机械法进行了比较。详尽地比较了球磨机与采用气流粉碎机工艺的能耗，并指出能耗费与维修费是影响低档次产品成本不可忽视的因素。     

表面活性剂在超细粉体制备和分散中的应用

综述了表面活性剂在超细粉体制备和使用分散过程中的应用;介绍了几种制备超细粉体的湿化学法,包括溶胶-凝胶法、化学沉淀法、微乳液法、水热合成法,并介绍了表面活性剂在其中的应用情况;简要说明了表面活性剂的分散机理及分散过程中存在的影响因素;随着超细粉体技术的不断发展,表面活性剂应用技术也在不断地发展,展望了表面活性剂在超细粉体材料领域的广阔应用前景。     

湿法制备ZrO2超细粉的团聚机理、表征及控制

团聚对陶瓷材料的显微结构、致密化及性能有相当大的危害，是超细粉和纳米陶瓷技术发展的一个难题。本文以湿法制备ZrO2超细粉过程为对象，综述了团聚体的形成机理、表征方法，着重介绍团聚体强度表征的进展状况，以及近年来团聚控制的新工艺。     

国内外超细粉体的应用及制备简介

超细粉体技术是指制备与使用超细粉体及其相关的技术,其研究内容包括超细粉体的制备技术,分级技术,分离技术,干燥技术,输送,混合与均化技术,表面改性技术,粒子复合技术,检测及应用技术等,目前超细粉体技术与设备已广泛用于军民各个领域,为国防现代化和国民经济作出了一定的贡献。超细粉体技术是一门综合性很强的技术,涉及知识面很广。     

我国超细粉体技术研究中一些重要而急待解决的问题

超细粉体技术是当今世界上很重要的科学技术之一。本文综述了我国超细粉体技术的研究现状，和今后研究中的一些重要而急待解决的问题。     

超细粉体在建筑卫生陶瓷工业中的应用

分析超细粉体技术在建筑卫生陶瓷工业中应用的现状，探讨超细粉体及其技术在传统建筑卫生陶瓷工业中应用的前景。     

超细粉体技术在无机矿物填料中应用的研究现状

综述了超细粉体技术在无机矿物作为橡胶补强填充剂中的应用。介绍了近年来超细粉碎技术、超细粉体的表面改性技术运用于无机矿物填料的研究现状。经超细粉碎、改性后的无机矿物可全部或部分代替炭黑等常规橡胶填料，从而降低橡胶生产成本。     

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.     

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.     

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.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.