CdSe/ZnS quantum dot-Cytochrome c bioconjugates for selective intracellular O2˙⁻ sensing

We demonstrate that the coupling system of negatively capped CdSe/ZnS QDs with an oxidized Cytochrome c (Cyt c) is capable of the fluorescent imaging of a superoxide radical (O(2)˙?) with high sensitivity and specificity in living cells, without interference from other Reactive Oxygen Species (ROS) or relevant intracellular components.     

Enhanced translocation of poly(dt)45 through an α-hemolysin nanopore by binding with antibody

The translocation time of poly(dT)(45) through an α-hemolysin pore was reduced in the presence of a DNA-binding Fab fragment. The Fab acts as a rudder to steer the DNA into the pore.     

Characterization of metabolism of (+)-praeruptorin B and (+)-praeruptorin E in human and rat liver microsomes by liquid chromatography coupled with ion trap mass spectrometry and time-of-flight mass spectrometry

Peucedani Radix is a Chinese medicinal herb noted for its effects on treatments of respiratory and pulmonary disorders. As a part of a systematic pharmacokinetic evaluation of the herb in our laboratory, the present study investigated, for the first time, the metabolic profile of (+)-praeruptorin B (dPB) and (+)-praeruptorin E (dPE), two main bioactive constituents of Peucedani Radix in pooled liver microsomes of rats (RLMs) and humans (HLMs). dPE was eliminated faster than dPB in both species. The incubation of dPB with RLMs and HLMs resulted in eight (B1-B8) and nine (B1-B9) metabolites, respectively, while both RLMs and HLMs converted dPE into 13 metabolites (E1-13). Structures of all the metabolites were proposed through comparing their mass data obtained via tandem mass spectrometry on an MSD ion trap system (IT-MS/MS) coupled with high-resolution mass measurement by time-of-flight mass spectrometry (TOF-MS) with those of the respective parent compound. B1 and E1 were unambiguously identified as (-)-cis-khellactone. The formations of all the metabolites were NADPH-dependent. Oxidation and hydrolysis were demonstrated to be two predominant metabolic pathways of dPB and dPE. Oxidation initiated at either the C-3' or C-4' substituent, while hydrolysis only started from the C-3' substituent. Fragmentation of all metabolites followed similar pathways to those of the parent pyranocoumarins. The information on metabolic properties of dPB and dPE and the mass fragmentation profiles of their metabolites obtained in the present study will aid in characterization of metabolic profiles of other angular-type pyranocoumarins and further investigation of in vivo fates of these pyranocoumarins and the herb.     

Dynamic tracking of pathogenic receptor expression of live cells using pyrenyl glycoanthraquinone-decorated graphene electrodes

Expression of specific transmembrane receptors by cells frequently represents an important signature of diseases, but this dynamic event can hardly be monitored directly with live cells due to the limitation of current biochemical techniques. Here we develop a pyrenyl glycoanthraquinone construct that can be firmly immobilized on a graphene-spotted screen printed electrode via strong π-interactions. The inherent current signal produced by the surface-confined glycoquinone can be used to detect selective sugar–protein recognitions with simple electrochemical techniques and portable facilities. Importantly, we demonstrate that the level of pathogenic receptors expressed by different types of live cells can be tracked with the electrode system in a label-free manner, providing a useful tool for the on-demand disease diagnosis as well as basic biochemical studies.     

硝酰自由基光电子能谱的理论研究

本文采用谐振子模型,考虑Duschinsky效应,推得计算三维Franck-Condon因子的代数表示,且应用于研究硝酰自由基的光电子能谱的强度分布及振动结构。对于HNO((?)~3A″)-HNO~-((?)~2A″)光脱附过程,通过Franck-Condon因子计算,得到光电子能谱的谱线相对强度,理论上计算的光电子能谱与实验观测到的光电子能谱达到较好的一致;另外,在光谱模拟过程中,通过迭代Franck-Condon分析,拟合实验能谱得到阴离子HNO~-自由基(?)~2A″电子态的几何结构:键长R(NO)是0.1335±0.0005 nm,键角∠(HN())是106.3±0.5°.     

"点石成金?"--碳结构超高压物理力学

文章介绍了石墨和碳纳米管在超高压和／或纳米压痕下的层间sp^2-sp^3键转化、软硬相转换、纳米硬度等研究进展．通过量子力学和分子动力学建模分析研究，发现超高压下石墨和碳纳米管存在软相向硬相转变的双相机制，给出了超高压获取石墨和碳纳米管超硬相的条件．理论计算与实验结果吻合很好，并能合理地解释有关石墨和碳纳米管超高压实验中看似矛盾的各种实验现象．提出了碳结构超高压物理力学概念，可为超高压碳相关物质相变、物化性质调控提供理论方法．     

Study of He-induced nano-cavities as sinks of oxygen for forming silicon-on-insulator

In the present work, a Cz-Silicon wafer is implanted with helium ions to produce a buried porous layer, and then thermally annealed in a dry oxygen atmosphere to make oxygen transport into the cavities. The formation of the buried oxide layer in the case of internal oxidation （ITOX） of the buried porous layer of cavities in the silicon sample is studied by positron beam annihilation （PBA）. The cavities are formed by 15 keV He implantation at a fluence of 2×10^16 cm^-2 and followed by thermal annealing at 673 K for 30 min in vacuum. The internal oxidation is carried out at temperatures ranging from 1073 to 1473 K for 2 h in a dry oxygen atmosphere. The layered structures evolved in the silicon are detected by using the PBA and the thicknesses of their layers and nature are also investigated. It is found that rather high temperatures must be chosen to establish a sufficient flux of oxygen into the cavity layer. On the other hand high temperatures lead to coarsening the cavities and removing the cavity layer finally.     

氦离子注入4H-SiC晶体的纳米硬度研究

4H-SiC晶体经能量为100 keV,剂量为3×10¹⁶ cm^-2的氦离子高温（500 K）注入后,再在773—1273 K温度范围内进行了退火处理,最后使用纳米压痕仪测量了样品注入面的硬度.测试结果表明,在500—1273 K温度范围内样品的硬度随退火温度升高呈现先增大后减小再增大的趋势,其中773 K退火样品的硬度增大明显.分析认为,退火样品的硬度变化是由退火过程中缺陷复合与氦泡生长导致样品内部的Si—C键密度、键长和键角改变引起的. 关键词： SiC 注入 氦泡 纳米压痕     

Spectroelectrochemical Study on Radical Intermediate of Coenzyme Q10 at Silver Electrode

The radical intermediate (ubisemiquinone) of CoenzymeQ₁₀ (CoQ₁₀) had been observed in nonpolar solvents by spectroscopic techniques.1 The present work investigates the radical speices, as well known, it is extremely unstable in polar solvents, in ethanol/water system through spectroelectrochemical techniques including in situ UV/Vis,EPR and NMR.