MnFe_2O_4@PANI@Ag Heterogeneous Nanocatalyst for Degradation of Industrial Aqueous Organic Pollutants

This paper reports a stable heterogeneous nanoparticles catalyst MnFe_2O_4@PANI@Ag for the degradation of azo dyes.In this synthesizing method,MnFe_2O_4 is used as magnetic core and polyaniline(PANI)a linker to stabilize the Ag nanoparticles(NPs) on the surface of catalyst.The method has a high ability to prevent Ag NPs from aggregation on the PANI surface,thus resulting in small size and highly dispersed Ag NPs.The composition and nano-structural features of polycrystalline sample were studied by X-ray powder diffractometry,Fourier transform infrared spectroscopy,and scanning electron microscopy.Vibrating sample magnetometer measurements proved the super-paramagnetic property of the catalyst,and UV results demonstrated that MnFe_2O_4@PANI@Ag has a high ability to reduce the azo dyes,which come from industrial wastes in the form of pollutant.The nanocomposites could be readily separated by magnet and reused for the next four reductions with high generation efficiency.     

n-Al2O3/Ni复合电刷镀层的接触疲劳行为

为研究纳米颗粒复合电刷镀层的接触疲劳行为,通过在镍盐溶液中加入纳米氧化铝(n-Al2O3)颗粒,采用电刷镀技术制备了含n-Al2O3颗粒的镍基复合镀层(n-Al2O3/Ni),采用接触疲劳试验机评价了镀态和热处理态的n-Al2O3/Ni复合镀层的抗接触疲劳性能,并与纯镍刷镀层进行了性能对比.借助SEM和TEM对复合刷镀层的组织进行了分析,探讨了复合刷镀层的接触疲劳失效过程以及纳米颗粒等对刷镀层疲劳失效过程的影响.研究表明:n-Al2O3/Ni复合镀层在镀态下的接触疲劳寿命超过100万周次,明显高于纯镍镀层;退火后n-Al2O3/Ni复合镀层接触疲劳寿命为45.9万次,为纯镍镀层的1.62倍;复合镀层的接触疲劳失效过程分为裂纹萌生、裂纹扩展和镀层断裂3个阶段;纳米颗粒在复合镀层接触疲劳失效过程中起到阻碍位错滑移的作用,从而抑制塑性变形和裂纹扩展,使复合镀层具有较高的接触疲劳寿命.     

Functional properties of ceramic-Ag nanocomposite coatings produced by magnetron sputtering

In recent years, the use of nanocomposite materials to functionalize surfaces has been investigated, taking advantage of the complementary properties of the nanocomposite constituents. Among this family of materials, ceramic-Ag coatings have been widely studied due to the large variety of functionalities that silver possesses and the possibility of tuning the coating’s practical features by selecting the proper matrix to support this noble metal. Therefore, this review focuses on the effects of silver nanoparticles on the functional properties of ceramic-Ag nanocomposites. The chemistry, structure, morphology and topography of the coatings are analyzed with respect to the changes produced by the silver nanoparticles’ distribution, amount and sizes and by altering production process variables. To offer a clear understanding of the functionalities of these materials, the optical, electrical, mechanical, tribological, electrochemical and biological properties reported in the last decade are reviewed, focusing on the ability to tune such properties by modifying the silver distribution, morphology and composition. In particular, the surface plasmon resonance, self-lubricating ability and antibacterial effect of silver are covered in detail, establishing their correlation with factors such as silver diffusion, segregation and ionization.     

载银纳米磁粒抗菌剂的研究

采用双层包裹法首次制备出载银磁粒抗菌剂.并对样品进行SEM、XRD、IR、磁性参数分析和抗菌性能研究,结果显示磁粒抗菌剂的平均粒径为75nm,粒径均匀,基本呈圆球型.二氧化硅以无定形状态存在,银以银单质出现在纳米粉体中.磁粒抗菌剂的饱和磁化强度比纳米铁氧体减小,但仍具有好的磁性.银含量＞3.87%时,对大肠杆菌和金黄色葡萄球菌都有99.9%的杀菌性能.     

银系抗菌剂对包装原纸性能的影响

目的 研究银系抗菌剂对包装原纸抗菌性能、白度和力学性能的影响。方法 选用乙酸银、纳米银、磺胺嘧啶银等3种不同的银系抗菌剂,采用表面涂布的方法制备出抗菌纸;选用大肠杆菌和金黄色葡萄球菌检测其抗菌性能;比较抗菌纸和空白试样的力学性能。结果 3种抗菌纸对大肠杆菌和金黄色葡萄球菌均有一定的抗菌效果,抑菌圈直径为0.35~5.46 mm,其中对金黄色葡萄球菌的抗菌效果最为明显;当抗菌液的质量分数为0~0.5%时,随着浓度的增加,乙酸银抗菌纸的抗菌性能随之增加;当抗菌液的质量分数为0~10%时,随着浓度的增加,纳米银抗菌纸的抗菌性能也逐渐增加;当抗菌液的质量分数为0.6%时,磺胺嘧啶银抗菌纸抗菌性能达到最佳;抗菌剂对包装原纸白度有一定影响,但对力学性能的影响不明显。结论 3种抗菌纸对金黄色葡萄球菌的抗菌效果比对大肠杆菌的优良,抗菌纸的抗菌性能与抗菌剂种类和浓度有关;抗菌处理对包装原纸的力学性能和表面结构影响不大,但乙酸银和纳米银抗菌剂会导致纸张白度的下降。     

铝电解用NiFe2O4型金属陶瓷惰性阳极的研究进展

介绍了国内外铝电解用NiFe2O4型惰性阳极材料的研究与开发进展情况.该材料在具有耐熔盐腐蚀、抗氧化、电阻率低等优点的同时也存在有抗热震性能差和电连接困难等缺陷.此外,简要阐述了NiFe2O4型惰性阳极的主要制备工艺.     

Facile route for preparation of silica-silver heterogeneous nanocomposite particles using alcohol reduction method

Silica-silver heterogeneous nanocomposite particles were successfully prepared by facile route including alcohol reduction method. Thiol groups were employed as a chemical protocol to make a binding between silver nanoparticle and silica surface. After the reaction for 10 min, a large number of quasi-spherical silver nanoparticles with an average size of 6.9 nm in diameter were homogeneously formed on the surface of silica particles. The immobilized silver nanoparticles grew to large ones with an average size of 10.6 nm in diameter after additional reaction for 2 h. The resulting nanocomposite particles were characterized by transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), UV-vis spectrophotometer, and X-ray diffraction (XRD) analysis.     

Optical and morphological characterisation of a silver nanoparticle/fluorescent poly(phenylenethynylene) composite for optical biosensors

Thiol silver nanoparticles prepared by the phase transfer method have been mixed with a fluorescent poly(phenylenethynylene) sequenced with dithioester-diethylsulfide moieties in order to develop a nanocomposite for its possible application in optical biosensors for the detection and attack of fungi such as Paecilomyces variotii. Films have been prepared by dipping technique and characterized by AFM, XPS, UV-Visible and fluorescence spectroscopy. Optical Absorption properties of the nanocomposite are similar to those of the polymer with an absorption tail in the visible which supports the presence of silver nanoparticles. Despite the lack of fluorescence of the nanoparticles, the composite emits in the yellow green region and the intensity of the fluorescence of the nanocomposite film decreases after the immersion in the culture thus permitting the detection of the fungus by this technique. The fungus can be deposited on films of both the polymer and nanocomposite, nevertheless only in the latter case, an attack on mycelium is observed revealing the fungicidal effect of silver nanoparticles in the nanocomposite.     

One-step synthesis of reduced graphite oxide–silver nanocomposite

Here, a general approach for the preparation of reduced graphite oxide (rGO)–silver nanocomposite has been investigated. Graphite oxide (GO) sheets are used as the nanoscale substrates for the formation of rGO–silver composite. GO sheets and Ag ions can be reduced at the same time, under a mild condition using l-ascorbic acid (l-AA) as reducing agent. This simple approach should find practical applications in the production of rGO–silver nanocomposite. The SEM analysis indicates that the silver particles are dispersed on graphene sheets. Raman signals of rGO in the composite are increased by the attached silver nanoparticles, displaying surface-enhanced Raman scattering activity. The degree of enhancement can be adjusted by varying the quantity of silver nanoparticles in the composite. In addition, antibacterial activity of the composite against Escherichia coli was evaluated using zone of inhibition. Composites with Ag clearly showed antibacterial activity against E. coli. While GO alone has almost no effect against this bacteria.     

Novel nanocomposite coating for dental implant applications in vitro and in vivo evaluation

This study aimed at preparation and in vitro and in vivo evaluation of novel bioactive, biodegradable, and antibacterial nanocomposite coating for the improvement of stem cells attachment and antibacterial activity as a candidate for dental implant applications. Poly (lactide-co-glycolide)/bioactive glass/hydroxyapatite (PBGHA) nanocomposite coating was prepared via solvent casting process. The nanoparticle amounts of 10, 15, and 20 weight percent (wt%) were chosen in order to determine the optimum amount of nanoparticles suitable for preparing an uniform coating. Bioactivity and degradation of the coating with an optimum amount of nanoparticles were evaluated by immersing the prepared samples in simulated body fluid and phosphate buffer saline (PBS), respectively. The effect of nanocomposite coating on the attachment and viability of human adipose-derived stem cells (hASCs) was investigated. Kirschner wires (K-wires) of stainless steel were coated with the PBGHA nanocomposite coating, and mechanical stability of the coating was studied during intramedullary implantation into rabbit tibiae. The results showed that using 10 wt% nanoparticles (5 wt% HA and 5 wt% BG) in the nanocomposite could provide the desired uniform coating. The study of in vitro bioactivity showed rapid formation of bone-like apatite on the PBGHA coating. It was degraded considerably after about 60 days of immersion in PBS. The hASCs showed excellent attachment and viability on the coating. PBGHA coating remained stable on the K-wires with a minimum of 96% of the original coating mass. It was concluded that PBGHA nanocomposite coating provides an ideal surface for the stem cells attachment and viability. In addition, it could induce antibacterial activity, simultaneously.     

超小型Fe3O4/Au纳米复合微粒的制备与表征

用反向微乳液法成功制备了超小型Fe3O4/Au磁性纳米复合微粒,并利用3-巯基丙酸将复合微粒直接从微乳液分离到有机溶剂中.用UV-Vis、VSM和TEM对产物进行了鉴定与表征,结果表明复合微粒分散良好,平均粒径为6.7nm,饱和磁化强度为9.7A·m2/kg.     

Nd1-xSrxMn1-yCuyO3/NiFe2O4复合体系的磁电阻效应研究

采用溶胶-凝胶法制备了Nd1-xSrxMn1-yCuO3(x=0．33、0．2,y=0．05、0．2)微粉,平均粒径约为150nm;采用化学共沉淀法制备了NiFe2O4;微粉,平均粒径为70nm;将两种粉体充分混合、压成片状后烧结成多晶块体复合材料。经测量NiFe2O4质量百分比为30％的Nd0.67Sr0.33Mn0.8Cu0.2O3／NiFe2O4复合样品在1．8T磁场作用下,在293～315K温度范围内磁电阻MR基本保持在-13．6％．说明在室温附近温度稳定性较好。     

添加TiO2对镍铁尖晶石惰性阳极材料性能的影响

为了提高惰性阳极材料的性能,本文尝试在合成镍铁尖晶石过程中掺杂一定量TiO2.采用高温固相反应法在1200℃下烧结6h,制备掺杂TiO2的镍铁尖晶石惰性阳极材料.研究了掺杂TiO2对试样密度、电导率和腐蚀率的影响.研究结果表明,掺杂TiO2后NiFe2O4的晶格产生畸变,从而TiO2促进烧结,提高材料的密度.并且由于Ti4 离子取代Fe3 离子,产生导电电子,改善了NiFe2O4惰性阳极材料的导电性.添加0.5%TiO2可降低材料的腐蚀率,但随着添加量的增加腐蚀率也增加,说明TiO2对材料的抗腐蚀性不利.经研究发现腐蚀率降低的原因是腐蚀过程中NiFe2O4分解产生的Fe2O3与电解质中Al2O3反应生成了FeAl2O4.综合考虑TiO2对材料各性能的影响,最终确定掺杂量为0.5%.     

Polyaniline–CuO hybrid nanocomposites: synthesis, structural, morphological, optical and electrical transport studies

Thin films of semiconducting polyaniline (PANi) nanofibers reinforced with copper oxide (CuO) nanoparticles (NPs) were prepared on glass substrate using spin coating technique. Polyaniline (PANi) have been synthesized by chemical oxidative polymerization method with monomer aniline in presence of (NH₄)₂S₂O₈ as an oxidant at 0 °C. The copper oxide (CuO) nanoparticles were synthesized by sol–gel method. Physical properties of nanocomposite (NCs) films were characterized and analyzed by X-ray diffraction, Scanning electron microscopy, Fourier transform infrared (FTIR) spectroscopy, UV–vis spectroscopy, Two probe resistivity measurement technique and Thermo-emf measurement. Structural analysis showed that the crystal structure of CuO is not disturbed in the PANi–CuO hybrid nanocomposite. Surface morphology study shows the uniform distribution of CuO nanoparticles in PANi matrix. FTIR and UV–Visible studies confirm the presence of polyaniline in emeraldine base form in the composites and suggest incorporation of CuO in polymer. Two probe electrical resistivity measurements of nanocomposites (NCs) film revealed that the resistivity of PANi increases with increasing content of CuO NPs.     

Extracellular biosynthesis,characterisation and in-vitro antibacterial potential of silver nanoparticles using Agaricus bisporus

Microbial silver nanoparticles have been known to have bactericidal effects but the antimicrobial mechanism has not been clearly revealed. The use of microorganisms in the synthesis of nanoparticles emerges as an ecofriendly and exciting approach. Here we report on the extracellular synthesis method for the preparation of silver nanoparticles in water using the extract of Agaricus bisporus, a naturally occurring edible mushroom, as reducing and protecting agents. The silver nanoparticles were characterised by ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR) and X-Ray diffraction (XRD) analysis. The synthesised silver nanoparticles showed antibacterial activity against the multi-drug resistant Gram positive and Gram negative bacterial pathogens.     

Al2O3纳米粒子增强锌铝基耐蚀涂层的制备及性能研究

为解决锌铝基耐蚀涂层在高速、强摩擦等特殊服役条件下的使用问题,将Al2O3纳米粒子添加到锌铝基耐蚀涂层中进行改性,以提高涂层的硬度和耐蚀性.研究了Al2O3纳米粒子及其添加量对涂层硬度、摩擦系数、附着强度、耐冲击性能和耐腐蚀性能的影响,并对涂层的微观组织和成分进行了分析.结果表明,添加Al2O3纳米粒子可显著提高锌铝基耐蚀涂层的硬度和耐蚀性能,降低摩擦系数,且对涂层的附着强度和耐冲击性能无负面影响.Al2O3纳米粒子在涂层中的均匀分散是获得涂层优异综合性能的必要条件.     

Fabrication of silver nanocomposite films impregnated with curcumin for superior antibacterial applications

Silver nanocomposite films are found to be very effective material for anti-bacterial application. In the present work, sodium carboxylmethyl cellulose silver nanocomposite films (SCMC SNCF) were tried for antibacterial applications. To enhance their applicability novel film-silver nanoparticle-curcumin composites have been developed. SCMC SNCF are developed from sodium carboxylmethyl cellulose (SCMC), N,N ¹ -methylenebisacrylamide (MBA) and silver nitrate solution. These films were characterized by FTIR, UV–visible, XRD, TGA, DSC and TEM techniques. The formed silver nanoparticles have an average particle size of ~15 nm as observed by transmission electron microscopy (TEM). Curcumin loading into SCMC SNCF is achieved by diffusion mechanism. The UV–Visible analysis indicated that higher encapsulation of curcumin in the films with higher SCMC content. Further, it was observed that the presence of silver nanoparticles in the films enhanced the encapsulation of curcumin indicating an interaction between them. Moreover, the antibacterial activity showed that the SCMC films generated with silver nanoparticles have a synergistic effect in the antimicrobial activity against Escherichia coli (E. coli). In order improve the healing efficacy as antibacterial agents, curcumin loaded with SCMC SNCFs were developed which showed significant inhibition of E. coli growth than the silver nanoparticles and curcumin alone film. Therefore, the present study clearly provides novel antimicrobial films which are potentially useful in preventing/treating infections.     

添加剂对NiFe2O4尖晶石性能的影响

研究了3种添加剂对NiFe2O4尖晶石性能和微观结构的影响.对试样的体积密度、三点抗弯强度、抗热震性、导电率进行了测试,并结合SEM和EDX进行了微观结构分析.结果表明,添加剂M使试样的体积密度变化最快,含有3%M试样的抗弯强度较纯尖晶石提高了25MPa,添加T的试样热震性最好,添加剂M和T均能提高试样的导电能力.     

聚苯胺/银纳米复合材料的形貌对抗菌性能的影响

采用快速混合的方法一步原位合成了不同形貌的聚苯胺/银纳米复合材料。扫描电子显微镜证明,通过改变苯胺与硝酸银的物质的量比可使聚苯胺/银纳米复合材料的形貌由微球到纳米纤维的转变。X射线衍射分析表明,单质银的粒径随着苯胺与硝酸银的物质的量浓度比的减小而增大,聚苯胺仍保持特有的非晶态。紫外-可见光谱分析表明,银纳米粒子与聚苯胺分子间存在相互作用,且银粒子改变了聚苯胺的分子结构。抗菌性实验证明,聚苯胺/银纳米复合材料的形貌对抗菌性能有显著影响,聚苯胺/银纳米纤维有最优异的抗菌性能。     

Polyaniline–CdS nanocomposites: effect of camphor sulfonic acid doping on structural, microstructural, optical and electrical properties

Nanocomposites of CdS nanocrystals with conducting polyaniline doped with camphor sulfonic acid (CSA) have been prepared by spin coating technique and investigated by X-ray diffraction, field emission scanning electron microscopy (FESEM), fourier transform infra red spectroscopy (FTIR), UV–visible spectroscopy and electrical transport method. The X-ray diffraction patterns showed broad peaks due to formation of nanoparticles of CdS in polyaniline matrix. FESEM showed that the transformation of morphology from agglomeration to nanopetals. The FTIR spectra confirmed the interaction between CSA and polyaniline (PANi)–CdS nanocomposite. The UV–visible spectrums revealed the enhancement of doping level for the PANi–CdS nanocomposites which is assigned to the existence of greater number of charges on the polymer backbone. DC electrical conductivity studies showed an increase in conductivity of PANi–CdS nanocomposites from 6.9?×?10^?6 to 3.14?×?10^?4 due to addition of CSA (10–50?%).