Au nanoparticles as a novel coating for solid-phase microextraction

A novel solid-phase microextraction fiber based on a stainless steel wire coated with Au nanoparticles was prepared and has been applied, coupled with gas chromatography, to the extraction of aromatic hydrophobic organic chemical pollutants in rainwater and soil extract. The solid-phase microextraction fiber exhibited excellent extraction efficiency and selectivity. Effects of extraction time, extraction temperature, ionic strength, stirring rate and desorption conditions were investigated and optimized. Single fiber repeatability and fiber-to-fiber reproducibility were less than 7.90% and 26.40%, respectively. The calibration curves were linear in a wide range for all analytes. Correlation coefficients ranged from 0.9941 to 0.9993. The as-established SPME-GC method was used successfully to two real natural samples. Recovery of analytes spiked at 10 μg L(-1) and 100 μg L(-1) ranged from 78.4% to 119.9% and the relative standard deviations were less than 11.3%.     

Cu(L-His)2溶液配位结构的X射线吸收精细结构分析

采用X射线吸收精细结构分析(XAFS)方法分析Cu(His)₂复合物的配位模式,通过测定不同pH值下的铜的K边XAFS吸收谱,研究Cu(His)₂第一配位壳层的结构．为了更准确地验证Cu(His)₂配位结构,对组氨酸的羧基和咪唑分别进行了化学修饰．研究结果明确了在不同pH环境下组氨酸的羧基、氨基和咪唑的配位情况．对于争议最大的在生理pH值下组氨酸的配位方式,其结果更支持六配位模式,同时可能有少量的五配位模式配合物平衡存在.     

Fine structure of the isoscalar giant quadrupole resonance in Ca due to Landau damping?

The fragmentation of the Isoscalar Giant Quadrupole Resonance (ISGQR) in ⁴⁰Ca has been investigated in high energy-resolution experiments using proton inelastic scattering at Ep=200 MeV$E_{\mathrm{p}}=200\text{MeV}$. Fine structure is observed in the region of the ISGQR and its characteristic energy scales are extracted from the experimental data by means of a wavelet analysis. The experimental scales are well described by Random Phase Approximation (RPA) and second-RPA calculations with an effective interaction derived from a realistic nucleon–nucleon interaction by the Unitary Correlation Operator Method (UCOM). In these results characteristic scales are already present at the mean-field level pointing to their origination in Landau damping, in contrast to the findings in heavier nuclei and also to SRPA calculations for ⁴⁰Ca based on phenomenological effective interactions, where fine structure is explained by the coupling to two-particle–two-hole (2p–2h) states.     

Ion implantation effects on the microhardness and microstructure of GaN

We study the effect of N⁺ and O⁺ implantation on the microhardness and the microstructure of epitaxially grown GaN. The microhardness is measured using a Knoop diamond indenter while information on the effect of implantation on the surface morphology, microstructure and electronic structure is provided by atomic force microscopy, cross-section transmission electron microscopy and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. It is demonstrated that implantation increases the surface microhardness. A possible mechanism for the surface hardening effect is based on the formation of N interstitials that pin the dislocations and prohibit the plastic deformation. In addition to the hardening effect, the implantation induced N interstitials introduce a characteristic resonance in the NEXAFS spectra, at 1.4 eV below the absorption edge.     

有机化学品的生物降解性及构效关系

介绍了描述生物降解性的主要测定参数，测定过程的影响因素及常用的结构描述符，并结合实例综述了目前应用比较广泛的定量结构－生物降解性关系（QSBR）技术，最后，分析了QSBR工作存在的主要问题及研究前景。     

Highly efficient formation of metal and metal alloy particles from methyl metal compounds by a single pulse laser irradiation

Highly efficient processes for fine particle formation of metal alloys and metal oxides were developed using a high-power laser. In these processes, laser light was used only for the ignition of a thermal chain reaction. This reaction was suppressed by adding inert gases, and the suppression effect was in the order C₃H₈ > C₂H₆ > CH₄ > He > Ar > Xe. Oxygen accelerated the reaction because of the large exothermicity of the reaction of oxygen with methyl metal compounds.     

Factorization of the (relative) Chern character through Lie algebra homology

Karoubi's relative Chern character is constructed as a chain map factoring through Lie algebra chains.This is part of the author's doctoral thesis, Stanford University 1990.     

测量精磨玻璃表面破坏层深度的侧面观测法

本文主要介绍用侧面观测法测量精磨玻璃表面破坏层深度的试件制做、测试仪器；对精磨裂纹也做了一定的分析。     

Influence of MnO_2 Mineralizer on the Crystal Structure,Properties of SiC Kiln Furniture Bonded with Fine Silicon Powder

lINTRODUCTIONSiCkilnfllrniturepossessesgoodhigh-temperaturepropertiesandsmoothness.Itishighlyresistanttowarddeforming,slaggingandthermalshock.Thefurniturecanpracticallyresultinimprovingqualityandproductionofceramicsandiswidelyusedovertheworld.However,SiChassinteringtemperatureofupto2OOO:Ct13landitisdifficulttosinterasproductbyusingcommonkilnfurnace.Toserveashigh-temperaturerefractorykilnfurniture,itmustbemixedwithabonder.Thisworkus-esfinesiliconpowderasabonder,whichisadustproducedfroms…     

Measuring supersymmetry at the large hadron collider

The large hadron collider (LHC) should have the ability to detect supersymmetric particles if low-energy supersymmetry solves the hierarchy problem. Studies of the LHC detection reach, and the ability to measure properties of supersymmetric particles are currently underway. We highlight some of these, such as the reach in minimal supergravity space and correlation with a fine-tuning parameter, precision measurements of edge variables, anomaly or gauge-mediated supersymmetry breaking. Supersymmetry with baryon-number violation seems at first glance more difficult to detect, but proves to be possible by using leptons from cascade decays.