PVC用稀土热稳定剂研究进展

简要论述了聚氯乙烯（PVC）热降解机理及稀土热稳定剂的作用机理,着重介绍了国内外稀土类热稳定剂的研究进展,包括无机稀土热稳定剂和有机单一稀土热稳定剂及有机复合稀土热稳定剂,并对稀土热稳定剂的发展前景进行了展望。     

我国无铅热稳定剂有较大发展空间

正无铅热稳定剂的重点发展品种是稀土热稳定剂、有机锡热稳定剂和钙-锌复合型热稳定剂。我国企业在全球率先实现了稀土热稳定剂产业化,原料稀土元素主要是镧、铈类稀土化合物产品,安全卫生,无放射性,多年来用于出口塑料玩具的生产,在国际市场享有相当知名度。我国具有稀土资源优势,稀土热稳定剂应作为我国发展无铅热稳定剂的首选方向。复合型热稳定剂可综合多种热稳定剂特点,其中钙-锌复合型热稳定剂无毒无害,主要用于食品包装用塑料制品、保鲜膜产品等,但热稳定性不理想,要在更大     

稀土化合物作为高分子材料热稳定剂的研究进展

稀土化合物作为高分子热稳定剂具有优良的长期热稳定性,无毒环保,与其它热稳定剂具有协同作用。本文主要介绍了稀土热稳定剂在聚氯乙烯、硅橡胶和天然橡胶上的应用,概述了稀土与其它热稳定剂的协同作用与机理,并对稀土热稳定剂的应用和研究前景进行了展望。     

稀土热稳定剂在PVC／ACR中应用的研究

主要以有机锡热稳定剂为对比物,研究了稀土热稳定剂对PVC/ACR性能的影响。稀土热稳定剂对PVC/ACR的力学性能、加工性能都有不同程度的提高,稀土热稳定剂的热稳定性能符合PVC的加工条件,有望成为异型材的主流热稳定剂。     

PVC用稀土热稳定剂的研究进展

介绍了单一稀土和稀土—铅,稀土—有机锡及稀土—锌等稀土复合热稳定剂的研究现状,探讨了稀土复合热稳定剂的作用机理,并分析了稀土热稳定剂的发展前景。     

稀土型热稳定剂的性能与研究进展

概述了聚氯乙烯（PVC）的热降解机理及稀土型热稳定剂对PVC的热稳定作用机理,介绍了稀土型热稳定剂的主要性能,并对稀土型热稳定剂的发展现状进行详细阐述,指出稀土型热稳定剂未来的研究方向和发展趋势。     

稀土稳定剂的开发应用进展

综述了稀土稳定剂的合成方法及目前主要研究的进展;以及主要稀土类热稳定剂的应用性能、稀土复合热稳定剂及其应用的研究进展;并讨论了稀土热稳定剂的发展前景及对未来的展望。     

浅析聚氯乙烯稀土热稳定剂的稳定机理

介绍了稀土热稳定剂对PVC树脂的影响,阐述了稀土热稳定剂的性质,同时也探讨了稀土热稳定剂的发展前景。     

稀土对PVC材料热稳定性能的改进

稀土作为聚氯乙烯(PVC)的性能改进剂,具有优异的热稳定性、加工性和无毒环保特性,符合未来PVC热稳定剂发展的趋势,成为相关研究的重点。对近年来稀土热稳定剂的研究进行综述,以有机酸作为稀土元素适配体的热稳定剂是研究的重点。含氮杂环类、乙酰丙酮、水滑石、姜黄素等化合物也用作稀土元素的适配体。结果表明:稀土热稳定剂可明显提升PVC材料的热稳定性能,而加入硬脂酸钙、硬脂酸锌与化学助剂形成的复合型稀土热稳定剂,对PVC材料热稳定性的提升效果更佳。从稀土适配体化合物、复合型稀土热稳定剂以及减少生产成本等三个方面,指出稀土热稳定剂未来的发展方向。     

有机稀土稳定剂在PVO塑料建材中的应用进展

综述近年有机稀土在PVC塑料建材中应用;分析了稀土热稳定剂对PVC的稳定机理;介绍了稀土稳定剂的种类以及稀土热稳定剂;论述了多功能复合型稀土热稳定剂的特点和应用以及发展趋势。     

几种芽孢杆菌对温度、氨水和乙醇耐受性的研究

研究了枯草芽孢杆菌、巨大芽孢杆菌以及从土样中筛选的6种未知芽孢杆菌对温度、氨水和乙醇的耐受性。结果表明,水悬液中的芽孢在100℃处理3min后全部被杀死,土壤颗粒包裹的芽孢则需15min全部被杀死;从土样中筛选的6种未知芽孢杆菌在25％的氨水、75％的乙醇中分别浸泡7d后仍有存活。     

地方高校学生学习营养学知识符合社会发展趋势

地方高校学生主要面向地方经济,他们属于未来应用型实践性较高的专业人才.在调研和分析了我国高校开展营养学专业教育后,针对地方高校学生就业日益艰难的状况,提出了地方高校化学类专业学生学习营养学知识,具有专业优势,而对于未来报考(公共)营养师,拓宽就业面有较大的帮助,符合社会发展的潮流.     

荧光高分子应用研究进展

介绍了荧光高分子近年来在理论研究中与作为一种新型功能材料在实际中的应用研究进展。在理论研究中 ,它主要是以荧光探针技术来研究聚合物的微相动力学和构象 ,聚合物相转移和聚集行为 ,聚合物能量转移及光聚合过程。它作为功能材料 ,主要用于荧光化学传感器、非线性光学装置中 ,以及用作光导树脂等材料。     

High-Temperature Behavior of Indent and Creep-Nucleated Cracks in Vitreous-Bonded Alumina

Crack behavior was studied at elevated temperatures in a commercial vitreous-bonded alumina for two types of cracks: one introduced by indentation at room temperature and the other by the creep process. Indentation cracks with relatively small initial size grew progressively longer during creep before they became blunt and arrested; however, they continued to widen throughout the creep process. Larger indentation cracks under high stress condition continued to grow until failure. The evolution of creep-nucleated cracks was so fast that they were observed only in their arrested state. Once observed, their length remained essentially constant, but they did grow in width. The crack-opening displacement rates of both types of cracks were linearly related to the creep rate as predicted by fracture mechanics for stationary cracks. All but the specimens with the largest indentation crack exhibited flaw tolerance in that they failed by the coalescence of creep-nucleated cracks instead of the growth of a single crack. The results illustrate the crack behavior in the brittle-to-ductile transition regime for ceramics that deform by grain boundary sliding.     

Behavioral evidence for multicomponent trail pheromone in the termite,Reticulitermes flavipes (Kollar) (Isoptera: Rhinotermitidae)

Evidence is presented for a multicomponent trail pheromone in the eastern subterranean termiteReticulitermes flavipes (Kollar). Choice tests were used to compare strength and persistency of trails made by termites in glass tubes. Tubes connected to termite nests for 24 hr were marked by termites with an extremely long-lasting chemical that persisted for at least one year, and a highly volatile substance that decayed in 15 min. Individual termites varied the trail they deposited under different circumstances. When removed from the nest and placed in a clean tube, they deposited a highly volatile substance. They left stronger and more persistent trails when exploring clean tubes attached to the nest. When they discovered a new food source, they left trails that were more attractive and far more persistent than trails made by exploring or displaced termites. A food trail made by 15 workers was still effective after 24 hr, whereas a trail made by 50 displaced workers, walking one after another through a tube, lasted only 5 min.     

陶瓷基光子晶体的研究进展

采用以陶瓷材料为母体制备光子晶体是光子晶体制备的一个重要研究发展方向.本文介绍了陶瓷基光子晶体的几种主要的制备方法以及光子晶体在微波和红外、可见光频段中的应用.基于功能陶瓷所具有丰富的光/电功能可以制备陶瓷基光子晶体,文中介绍了可调带隙光子晶体和光子晶体中自发辐射方面的一些研究成果.陶瓷基光子晶体由于具有折射率高,功能广泛,制备手段多样等特点,因而具有广泛的应用前景,如用作电场调节的光开关和在显示领域中基于光子晶体各向异性发光特点的具有定向光发射性能的光源.     

Carotenoid pigments: structural and physicochemical considerations

Carotenoid are ubiquitous compounds serving a series of functions that make them special. Thus, they are regarded as essential compounds for life mainly due to the different roles they perform in photosynthesis as we currently know it. For many years, the nutritional relevance ot carotenoids was due to some of them exhibiting vitamin A activity, although the interest in these pigments has expanded dramatically in the last years owing to a large variety of surveys that seem to indicate that they are antioxidant and may be beneficial for the prevention of several chronic non-transmissible human diseases, albeit there is some controversy in this regard. In any case, it is clear that the different functions and effects attributed to these isoprenoids stem from their physical and chemical properties, the latter being due to their chemical structure. Due to the diverse benefitial actions carotenoids are responsible for and, above all, to their nutritional importance, the main objective of this review is to describe such features, whose knowledge is indispensable to have a holistic view of the different roles they play and for the design of new studies.     

关于化工专业建设与发展的几点思考

本文根据国内外化工专业培养模式和化工新技术发展对人才培养提出的复合型、创新型人才的需求,提出了新时期本科院校化工类人才培养模式的几点思考。探讨了以学生为中心,服务社会为目标,打造厚基础、强实践、重创新的课程体系,加强工程素养的培养,注重学生综合能力提高,切实引导学生对化工专业学习兴趣,从根本上提高学习动力,培养能够真正解决工程实际问题的社会急需的化工工程师。     

A review of resins used in construction: Types of resin — applications — case histories

The various ways in which resins can be used in structural applications are reviewed. Epoxy resin and polyester resins systems are described and compared for each application. Their use in adhesives, grouts,and mortars for both construction and repair work is compared with conventional materials, indicating where they can be used to advantage - always with the proviso that they are correctly formulated and applied.     

Overcoming tumor drug resistance with high-affinity taxanes: a SAR study of C2-modified 7-acyl-10-deacetyl cephalomannines

A series of C2-modified 10-deacetyl-7-propionyl cephalomannine derivatives was designed, prepared, and biologically evaluated. Some C2 meta-substituted benzoate analogues showed potent activity against both drug-sensitive and drug-resistant tumor cells in which resistance is mediated through either P-gp overexpression or beta-tubulin mutation mechanisms. The taxoid 15 b and related compounds are of particular interest, as they are much more cytotoxic than paclitaxel, especially against drug-resistant tumor cells; they are able to kill both drug-resistant and drug-sensitive cells (low R/S ratio), and they have high affinity for beta-tubulin. Our research results led to an important hypothesis, that is, a taxane with very high binding affinity for beta-tubulin is able to counteract drug resistance, which may assist in future taxane-based drug-discovery efforts.