Effect of Vacancy Defects on the Young's Modulus and Fracture Strength of Graphene: A Molecular Dynamics Study

The Young's modulus of graphene with various rectangular and circular vacancy defects is investigated by molecular dynamics simulation. By comparing with the results calculated from an effective spring model, it is demonstrated that the Young's modulus of graphene is largely correlated to the size of vacancy defects perpendicular to the stretching direction. And a linear reduction of Young's modulus with the increasing concentration of mono‐atomic‐vacancy defects (i.e., the slope of ?0.03) is also observed. The fracture behavior of graphene, including the fracture strength, crack initiation and propagation are then studied by the molecular dynamics simulation, the effective spring model, and the quantized fracture mechanics. The blunting effect of vacancy edges is demonstrated, and the characterized crack tip radius of 4.44 Å is observed.     

Development of a test strip based on DNA-functionalized gold nanoparticles for rapid detection of mercury(II) ions

A rapid,sensitive,selective and reliable strip assay based on DNA-functionalized gold nanoparticles for Hg²⁺ detection has been developed,with a detection limit 5 nmol/L.The measurement principle was based on thymine-Hg²⁺-thymine(T-Hg²⁺-T) coordination chemistry and streptavidin-biotin interaction.The major advantages of this assay are that results can be read visually without any instrument in less than 10 min and that it does not require any sample pretreatment.     

UPLC-ELSD Determination of 1-Octacosanol in Raw Material and Health Products

Determination of the levels of 1-octacosanol is important in food stuff for the study of its pharmacological activities and health benefits. In this study, a novel, simple and fast internal standard method for the non-derivatization ultra-performance liquid chromatographic determination of 1-octacosanol in raw materials and health products was developed and validated based on evaporative light scattering detection. The linearity (r ² > 0.998), recovery (99.1–100.2%, RSD <2.7%), intra- and inter-day precision (RSD <3.8%), limit of detection (1.0 mg/L), limit of quantification (2.2 mg/L) of the 1-octacosanol were determined. The method was successfully applied to nine real 1-octacosanol products. The results of analyses had close agreement with the labeled claims of 1-octacosanol content in these products. Compared with the classical gas chromatography method, the developed method was simpler, faster and more environmentally friendly due to avoiding any derivatization step. This protocol represents a rapid and feasible method for quality control of 1-octacosanol products.

     

Copper‐catalyzed Clauson–Kass pyrroles synthesis in aqueous media

An efficient and convenient copper‐catalyzed Clauson–Kass reaction of 2,5‐dimethoxytetrahydrofuran with amines in aqueous media has been developed, providing a wide range of N‐substituted pyrroles in good yields. It is noteworthy that the Clauson–Kass reaction of 2,5‐dimethoxytetrahydrofuran with p‐phenylenediamine or m‐phenylenediamine proceeds smoothly to afford the corresponding monopyrroles and bispyrroles with high selectivity in impressive yields. A plausible mechanism for the formation of N‐substituted pyrroles has been proposed. Copyright © 2012 John Wiley & Sons, Ltd.     

Biological evaluation of novel selenazole‐based compounds as potential thioredoxin reductase inhibitors

Recently, thioredoxin reductase as a target for treatment of tumors has attracted the attention of scientists. 1,2‐[Bis(1,2‐benzisoselenazolone‐3(2 H)‐ketone)]ethane (ethaselen, BBSKE, PCT: CN02/00412), designed and synthesized previously, is an effective thioredoxin reductase inhibitor; presently it is in phase II clinical trials, targeting gastric cancer, lung cancer and colon cancer. To seek more novel and effective anticancer drugs, we have developed many selenazole‐based compounds. Evaluation of the thioredoxin reductase inhibitory effect and investigation of the mechanism of anticancer drugs require abundant thioredoxin reductase, but since commercial thioredoxin reductase is expensive its use is often limited. Therefore, the preparation of thioredoxin reductase is necessary. Base on the above investigation, in this work we have prepared thioredoxin reductase and evaluated selenazole‐based compounds, and found that 44 compounds have high inhibitory effect on thioredoxin reductase with IC₅₀ < 10 µ m , of which 16 compounds have IC₅₀ values below 1 µ m . This is helpful in investigating and elucidating the mechanism of this kind of compound. Copyright © 2012 John Wiley & Sons, Ltd.