Synthesis and Characterization of Ag2S Nanocrystals in Hyperbranched Polyurethane at Room Temperature

Ag₂S nanoparticles in hyperbranched polyurethane matrix were prepared through the in situ reaction with thioacetamide as the sulfur source at room temperature. Transmission electron microscopic analysis revealed a uniform spherical shape for Ag₂S nanoparticles, with an average size of about 4-10 nm and a narrow size distribution. X-ray powder diffraction and UV-vis spectroscopy were also used to characterize the obtained nanoparticles     

Uniform Rice-like CdS Particles Prepared from Water-in-oil Microemulsions

IntroductionNano-sized semiconductors are of great interestdue to their special optical and electronic proper-ties[1,2].As one of the mostimportantⅡ—Ⅵsemicon-ductors,CdS has importantapplications in many fields,such as the solar cell field,non linear o…     

Surface status and size influences of nickel nanoparticles on sulfur compound adsorption

Metallic nickel nanoparticles were incorporated on mesoporous silica to remove sulfur compounds in diesel selectively. In the first method, nickel nanoparticles were formed on mesoporous silica SBA-15 by impregnation and subsequent reduction of nickel nitrate. The sulfur adsorption capacity was strongly dependent on the nickel loading and the average nickel particle size. In the second method, nickel nanoparticles were synthesized in solution in the presence of a capping agent and then incorporated in mesoporous silica MCF by sonication. Although these particles maintain their sizes on the MCF surface after heat treatment, capping agent remaining on the Ni particle surface might interfere the adsorption of sulfur compounds.     

Synthesis of Nanoscale Bimetallic Particles in Polyelectrolyte Membrane Matrix for Reductive Transformation of Halogenated Organic Compounds

Nanosized Fe/Ni and Fe/Pd particles were synthesized in the polyacrylic acid (PAA)/polyether sulfone (PES) composite membrane matrix for reductive transformation of halogenated organic compounds (HOCs). The advantages of using membrane to immobilize nanoparticles are the reduction of particles loss, prevention of particles agglomeration, and potential application of convective flow. Cross-linked PAA/PES composite membranes containing metal ions as particles precursor were prepared by heat treatment with ethylene glycol (EG) as a cross-linking agent. Nanoscale metal particles were formed and immobilized inside the membrane matrix after reduction with sodium borohydride. Membrane morphology and structure were observed by scanning electron microscopy (SEM). Particle size and distribution were characterized by SEM and transmission electron microscopy (TEM). Energy dispersive X-ray spectroscopy (EDS) was used to obtain the qualitative and quantitative element information of particles. A specimen-drift-free EDS line profile and EDS mapping system was performed in a scanning transmission electron microscopy (STEM) to determine the two-dimensional element distribution of iron and nickel in the nano domain. In the dechlorination study with trichloroethylene (TCE) as a representative HOCs, rapid and complete destruction of TCE was achieved by using nanosized bimetallic Fe/Ni or Fe/Pd in PAA/PES composite membranes. Typically more than 95% of 10 mg/l TCE was reduced within 1 h. Ethane was found in the headspace as the main product.     

金属纳米颗粒的热导率

本文使用统计模拟方法对金属纳米颗粒的电子平均自由程进行了计算,并考察了纳米颗粒的晶格比热和声子平均群速度,最后应用动力学理论对纳米颗粒的电子热导率和声子热导率分别进行了求解.研究结果表明:具有相同特征尺寸的方形、球形纳米颗粒的无量纲电子(或声子)平均自由程比较接近.金属纳米颗粒的电子热导率远大于声子热导率;电子、声子热导率随着直径减小呈现降低趋势,而电子热导率的颗粒尺度依赖性比声子热导率更为明显;随着颗粒直径进一步减小,声子热导率与电子热导率趋于同一数量级.当纳米颗粒特征尺寸大于4倍块材电子(或声子)平均自由程,其电子(或声子)热导率的颗粒尺度依赖性将减弱.     

DNA酶裂解-纳米金共振瑞利散射光谱法测定痕量Cu2+

在pH 7.0HEPES(4-羟乙基哌嗪乙磺酸)缓冲溶液中和0.19mol.L-1 NaCl存在下,单链底物DNA(SS)和酶链DNA(ES)在80℃杂交形成双链DNA(dsDNA)。Cu2+可切割dsDNA中的底物链释放出单链DNA(ssDNA),此ssDNA与金纳米粒子(NG)作用形成NGssDNA结合物不被NaCl聚集,而未保护的NG聚集形成较大粒径的聚集体(NGA),在627nm处有一个较强的共振瑞利散射峰。随着Cu2+浓度的增大,该共振瑞利散射峰降低,其降低值ΔI与Cu2+浓度在15～1 250nmol.L-1范围呈线性关系,其回归方程为ΔI=0.17c-2.3,线性相关系数为0.989 5,检出限为8nmol.L-1。据此建立了一个高灵敏、高选择性、简便测定Cu2+的共振瑞利散射光谱分析法。该法用于水样中Cu2+的检测,结果满意。     

Overcoming the Inhibition Effects of Citrate: Precipitation of Ferromagnetic Magnetite Nanoparticles with Tunable Morphology,Magnetic Properties,and Surface Charge via Ferrous Citrate Oxidation

This study demonstrates how the method of thermally assisted oxidative precipitation in water can be opened for—the so far neglected—metal organic iron(II) complexes (herein: citrate) in order to obtain, in one step, ferromagnetic magnetite nanoparticles, possessing essential ligand properties. Based on a dedicated analysis of the specific precursor in combination with the consideration of known properties of the ligand, it is possible to identify existing inhibition-attributes of the iron organyl such that these can be overcome. Moreover, they can be exploited in a targeted manner; thus, simply by changing concentrations, a variety of magnetite nanoparticle morphologies with distinct properties can be obtained. In the case of the herein investigated ferrous citrate, three major inhibition effects are identified. While two of them efficiently prevent the formation of magnetite and need to be addressed to be overcome, the third can be exploited to selectively synthesize, for example, relatively stable carboxyl group-bearing nuclei clusters, exhibiting the properties of magnetically responsive photonic crystals, or relatively large mesocrystals, whose intraparticular magnetic interactions are apparently disturbed.     

Nano‐Ruby: A Promising Fluorescent Probe for Background‐Free Cellular Imaging

Bioprobes based on fluorescent ruby nanoparticles, which are suitable for ultrasensitive imaging, are reported. A stable aqueous/buffer colloid, permitting facile conjugation to proteins, is produced by femtosecond laser ablation of ruby and the nanoparticles (mean size 17 nm) are photostable, with long lifetime (1–4 ms) 694 nm emission. With time‐gating complete (>20 dB) suppression of cell autofluorescence and suppression of exogenous fluorophores is observed. Nanoparticles are imaged in as‐grown cells and those immunolabeled with quantum dots. Immunoassay binding to target biomolecules is also demonstrated.     

Surface Coating Rescues Proteins from Magnetite Nanoparticle Induced Damage

The presence of magnetic nanoparticles (NPs) in physiological systems induces toxicity through its effects on mitochondrial function and reactive oxygen species (ROS) imbalance. Magnetic NP induced cytotoxicity has been elaborately evaluated for impending threats, however, a detailed investigation is lacking. It is shown that the interaction of Fe₃O₄ NPs with cytochrome c can lead to different events based on the NPs to protein ratio, the solution conditions, and the type of surface protection. At low NPs concentration, rapid binding and subsequent electron transfer are the preferred events while at higher concentration slow oxidative modification of the protein is initiated. The slow event of protein modification yields conformational disorientation, loss of stability, and formation of amyloid‐like structures with cytochrome c. The possibility that the NP induced oxidative stress and age can work in concert to compromise different aspects of cellular quality control processes is discussed. Suitable surface modifications of the NPs inhibit their direct binding to the protein molecules and minimize NP induced toxicity.     

Effect of Injection Parameters and Addition of Nanoscale Materials on the Shrinkage of Polypropylene Copolymer

The effect of variation of injection conditions and addition of nano-calcium carbonate (CaCO₃), nano-silicon dioxide (SiO₂) and full-vulcanized nano-powdered styrene butadiene rubber (PSBR) on the shrinkage of injection-molded polypropylene-ethylene copolymer (90/10, co-PP) were investigated. The results showed that the shrinkage was different for different locations along the flow path. The shrinkage in the length direction of the injection-molded sample varied with the adjustment of the processing parameters, while the shrinkage in the width and thickness direction was almost unchanged. The addition of nano-CaCO₃ and PSBR decreased the shrinkage of co-PP, while the shrinkage of co-PP/ SiO₂ composite was almost unchanged.