纳米银的制备及抗菌机理的研究进展

纳米银因其高效、广谱及不易产生耐药性等优点,已成为目前抗菌材料的研究热点,但其杀菌机理尚有待于进一步研究。本文介绍了纳米银的制备方法及其抗菌机理以及在化工催化、光学、电子工业、生物医药等方面的应用,并对其研究方向和应用前景进行展望。     

多形貌纳米银粒子的制备工艺研究

随着电子元器件向微型化、精密化和柔性化等方向发展,金属导电填料纳米化成为电子封装用导电银浆发展的必然趋势。其中,多形貌纳米银粒子的制备成为该领域的研究热点。采用液相还原法,通过多种表面活性剂的添加调控纳米银晶粒的生长过程,制备出球状、片状、立方状等多种形貌的银纳米粒子,并揭示了它们的生长机理。结果表明,随着聚乙烯吡咯烷酮(PVP)浓度的增加,纳米银颗粒的分散性得到逐步优化,当PVP浓度为2mmol/L时,制备出平均粒径为20nm左右且分散性良好的球状银纳米粒子;柠檬酸钠和双氧水的添加能够诱导纳米银颗粒向片状结构转变,当柠檬酸钠浓度为20mmol/L,双氧水浓度为25mmol/L左右时,有大量片状银纳米粒子的形成;氯化钠(NaCl)能够诱导纳米银颗粒向立方体结构转变,当NaCl浓度为20mmol/L时能够得到形状规则的立方银纳米粒子。     

纳米银的制备及其抗菌性的研究进展

纳米银抗菌材料已广泛应用于各个领域,并具有一定的生物安全性。关于纳米银的抗菌机理,作用过程较为复杂,主要有消耗细菌生活环境中的氧气、破坏细胞壁和细胞膜、抑制DNA分子复制及酶的活性等。纳米银的制备方法有物理、化学、生物等方法,其中生物还原法是一种新兴的制备手法,符合绿色环保理念,是未来研究的热点。纳米银的抗菌性能受多种因素影响,主要包括银颗粒尺寸、形貌、菌种、保护剂等因素。     

纳米银的合成及其抗菌应用研究进展

病原微生物严重威胁着人类的健康安全,纳米银作为一种新型抗菌材料,其制备与应用已成为纳米材料领域的研究热点。本文综述了纳米银的主要合成方法,包括多糖法、Tollens试剂法、辐射法、生物法和多金属氧酸盐法等,具有原料广泛、反应温和、成本低廉和环境友好等优点。基于纳米银的优异抗菌性能,总结了纳米银的抗菌机理及其抗菌应用,并展望了纳米银在抗菌涂料、抗菌包装等领域的发展前景。     

纳米银导电油墨的制备研究与包装应用概论

纳米导电油墨具有独特的物理及化学性质,而导电填料则决定导电油墨的性能。概述了纳米导电油墨的组成、分类及特点,主要论述了纳米银的特性,相较于其他填料,纳米银具备良好的导电性、导热性、纳米光学性、高比表面积等特性,因而纳米银作为导电填料成为了制备导电油墨的首选;进一步阐述了纳米银的制备方法及纳米银导电油墨的配方设计及制备工艺,通过不同的研究分析了纳米银导电油墨性能的影响因素,以及纳米银导电油墨在不同包装应用的发展趋势,并对其应用研究提出了建议。     

软模板技术制备银的各向异性纳米粒子

纳米银的光学、电学和催化活性与粒子的粒径、形貌和结构之间存在着强烈的依赖关系,研究各向异性银纳米材料的形成具有重要意义.结合软模板技术在各向异性银纳米材料制备方面的研究成果,着重讨论了银纳米棒和纳米线的制备方法和形成机理,概述了树枝状纳米银、纳米银片(盘)、纳米银立方体和三棱柱的研究进展,指出利用软模板技术可合成各种形貌的纳米银粒子,并指出了此类材料在研究中存在的不足,展望了其发展趋势.     

纳米银/聚苯乙烯核壳粒子的制备与表征

研究了纳米银粒子的表面修饰技术与纳米银/聚苯乙烯核壳粒子的制备技术,采用乳液聚合方法制备出纳米银/聚苯乙烯核壳粒子,并借助于TEM、XPS、FTIR分析了其微观结构。     

石墨烯/纳米银导电油墨导电性能研究

目的制备出具有优异导电性能的石墨烯/纳米银复合材料,并作为导电填料,以提高导电油墨的导电性能。方法采用Hummers法制备氧化石墨烯,以葡萄糖作为还原剂,采用同步还原法制备石墨烯/纳米银,将石墨烯/纳米银复合物和纳米银按不同比例混合作为导电填料来制备导电油墨。通过透射电镜(TEM)、X射线衍射(XRD)、傅里叶变换红外(FTIR)光谱等分析测试方法表征了石墨烯/纳米银复合材料的微观结构和形貌,并通过四探针法对油墨的导电性进行检测。结果纳米银颗粒均匀地负载在石墨烯片层上,纳米银粒径约为35 nm;掺杂石墨烯/纳米银复合物质量分数为12%时,导电油墨的电阻率可达到1.08×10~(-7)?·m,导电性能提高约64%。结论制备的复合材料石墨烯呈片状,结构完好,添加到导电油墨中能明显提高导电性能。     

石墨烯/纳米银导电油墨导电性能研究

目的 -制备出具有优异导电性能的石墨烯/纳米银复合材料,并作为导电填料,以提高导电油墨的导电性能。方法 -采用Hummers法制备氧化石墨烯,以葡萄糖作为还原剂,采用同步还原法制备石墨烯/纳米银,将石墨烯/纳米银复合物和纳米银按不同比例混合作为导电填料来制备导电油墨。通过透射电镜(TEM)、X射线衍射(XRD)、傅里叶变换红外(FTIR)光谱等分析测试方法表征了石墨烯/纳米银复合材料的微观结构和形貌,并通过四探针法对油墨的导电性进行检测。结果 -纳米银颗粒均匀地负载在石墨烯片层上,纳米银粒径约为35nm;掺杂石墨烯/纳米银复合物质量分数为12%时,导电油墨的电阻率可达到1.08×10~(-7)Ω·m,导电性能提高约64%。结论 -制备的复合材料石墨烯呈片状,结构完好,添加到导电油墨中能明显提高导电性能。     

片状氧化铝粉体的制备及应用

片状氧化铝粉体材料由于其独特的结构和优异的性能被广泛应用到颜料、化妆品、汽车漆料、耐火材料、增韧陶瓷等各个领域.综述了片状氧化铝的各种制备方法和国内外研究进展,并对其制备方法的优缺点进行了评价,阐述了片状氧化铝的形成机理及应用领域.     

Effect of Permeable Crystalline Material on Steel Reinforcement Corrosion of Concrete

Permeable crystalline materialcan permeate into pores and cracks of concrete and catalyze the reaction between Ca(OH) 2and unhydrated cement to generate a great quantity needle non-soluble crystals, which can stop up the pores and cracks of concrete, and increase the impermeability of concrete. This paper reported the results of a study conducted to evaluate steel reinforcement corrosion of concrete specimens uncoated and coated with permeable crystalline material as well as mixed with the permeable crystalline material. The properties evaluated for corrosion test were water impermeability, water absorption, compressive strength and potential. The results of water impermeability, water absorption, compressive strength clearly showed that the permeable crystalline material could prohibit water, any soluble salts and moisture from penetrating the concrete to cause corrosion, leaking, and other problems, and it did increase the compressive strength, which was favorable for protection of corrosion of reinforcing steel. Moreover, it was concluded from the potential-time curve that the steel reinforcement of uncoated specimen was in the state of activation whereas that of other specimens coated and mixed with the permeable crystalline material was in the state of inactivation. Above all, it was indicated that the permeable crystalline materialis very effective to protect the steel reinforcement of concrete from corrosion.     

The Research and Application About "Dry Peeling Off" Technology for Airplane Surface Paint Layer

In this paper, the principle of spurting take off lacquer were introduced; and with orthogonal method the unsaturate polyester was prepared ;it was easy to peel airplane paint layer off with this material and equipment.     

Quality Study of Honeycomb Core Shaping Without Wax Stabilization

Sandwich panels utilizing honeycomb cores result in lightweight, high-strength units that are very rigid. Indeed, they give honeycomb panels the best strength-to-weight ratio of any construction type available. Conventionally, the wax is poured into the cell of the core to strengthen the structure and prevent the core from being crushed during milling. Much time and labor is required to wax, mill, and clean the cores. In this study, the process of pouring wax into the core was skipped. In other words, the cutter directly milled the core. Experiments showed that the compressive strength of the core produced without wax stabilization was only 3% lower than that of cores produced using the traditional method. In addition, the drum peel strengths of cores produced without wax stabilization were 38.4% higher than cores produced using the traditional method, in which residual wax seriously polluted the adhesive. It was also found that eliminating the wax process can reduce costs.     

In-process thermal treatment of polylactic acid in fused deposition modelling

Polylactic acid (PLA) is one of the most widely used open source fused filament fabrication materials due to its ease of extrusion, biodegradability, and mechanical strength. The mechanical strength of PLA largely depends on the proper growth of its semi-crystalline structure, which can be severely impaired by a low rate of crystallization, particularly in open source printers. This can be further aggravated by the non-uniform thermal distribution of heat that causes improper curing among the extruded beads of the printing material. As a result, PLA printed on open source printers does not achieve the best mechanical properties. This research, for the first time, proposes an additive-free solution implemented through a detailed set of experimentation to improve the curing rate through in-process temperature variations to cure the joints among the beads. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy is used to confirm the improvements in the bead joints. This work is conducted in two phases of experiments. In the first phase, a full factorial ANOVA is used to investigate various process parameters and the important variables are used in the second phase to print test specimens in four different sets.     

Investigation of the Corrosion Behaviors of HVOF-Sprayed Carbide Cernet Coatings in Molten Al-Zn-Si Alloy Bath

In continuous hot-dip galvanization process the corrosion and chemical stability of the sink roll in the galvanizing bath are important problem which effects on the quality and productivity. In order to protect the sink roll the carbide cermet and/or ceramic coatings were deposited on the surface of the sink roll. The WC-, Cr3 C2-cermet coatings were deposited by high velocity oxygen fuel (HVOF) spray, respectively. The coating samples were immersed in molten Zn-alloy containing 50 wt % aluminum at 833 K for 24 hr and 144 hr, respectively. The inter-diffusion and inter-reaction of Zn, Al and elements in coating and corrosion behaviors of these coatings were investigated by XRD, SEM and EPMA etc. The corrosion mechanisms of the carbide cermet coatings and ceramic coatings in molten High Al-Zn-alloy were approached.     

Fundamental study of adhesion of ice to cooling solid surface (Discussion on influence of copper oxide layer on ice adhesion force)

In many situations, ice often adheres to a cooling solid surface, frequently causing serious accidents. It is critical to clarify the mechanism of ice adhesion to the cooling surface in order to prevent ice adhesion. In a past study, the shearing stresses of two kinds of test plates with a copper surface having the higher thermal conductivity were measured. The shearing stress corresponds to ice adhesion force. Both shearing stresses were significantly different; however, the cause remains unclear.Therefore, the present study focuses on an oxide layer as the main factor causing the difference of both shearing stresses; the influence of the oxide layer formed on shearing stress was discussed. And in the removal and reformation processes of the oxide layer, the time variation of the shearing stress was clarified. Moreover, the relationship between the state of the copper surface and the shearing stress was also clarified by surface analysis.     

＂Three Transformations＂ and Standardization

During his inspection in Henan Province in May, Chinese President Xi Jinping stressed to ＂push forward the transformation from China Speed to China Quality, from Made in China to Created in China, and from Chinese Products to Chinese Brand＂. The ＂Three Transformations＂ are the specific requirements and goal of China＇s national development in the context that market should play a decisive role in the allocation of resources.     

重塑标准推行格局 推动LED照明的普及（英文）

正When you are enjoying the green,energy-saving and healthy lighting of IKEA LED luminaire,you may not realize that most of IKEA’s LED bulbs are produced by the LED luminaire smart manufacturing system of Hangzhou Zhongwei Photoelectricity CO.,LTD(ZVISION).No longer enclosed in the laboratory,the product standards are brought into the factory workshop and even to the entire production process.Thus,the standards are promoted and applied in a favorable way by enterprises,benefitting consumers with high quality products.     

Chinese Experts Contribute to ISO＇s New Toy Standards

正The international standard,ISO 8124-6,Safety of toys–Part 6:Certain phthalate esters in toys and children’s products,was officially issued by ISO worldwide on August 15.It was the first time for Chinese experts to lead the ISO standard development in toys industry.The standard was drafted by a group of Chinese experts from SAC/TC for toys and relevant Chinese departments and finally completed by a dedicated international group of experts.ISO 8124-6 makes a substantive breakthrough in the aspects of the scope of toys,limitation of plasticizer types,control of test cost,accuracy of test,operation convenience,etc.,offering the operational guidance for toy manufactures and testing laboratories.     

SAC Delegation Visits AENOR and Signs Cooperation Agreements

正SAC Administrator Tian Shihong led the Chinese delegation to visit the Spanish Association for Standardization and Certification(AENOR)on September 15,2014.Mrs.Begona Cristeto,the Vice-Minister of Industry,Energy and Tourism of Spain,and Mr.Avelino Brito,the President and CEO of AENOR greeted the delegation.The two sides had a deep and friendly discussion on strengthening the cooperation between China and Spain in the standardization field and promoting the standardization work to support the development of economy and trade in the two countries.