Recent advances in metal-free catalysts for the synthesis of cyclic carbonates from CO_2 and epoxides

The aim of ＂green chemistry＂ and ＂atom economy＂ is to utilize carbon dioxide and replace harmful reactants such as CO and phosgene for the production of cyclic carbonates. In this paper, metal-free catalysts including organic bases, ionic liquids, supported catalysts, organic copolymers and carbon materials for the synthesis of cyclic carbonates by the cycloaddition of carbon dioxide to epoxides are reviewed. Recent advances in the design of the catalysts and the understanding of the reaction mechanism are summarized and discussed. The synergistic effects of organic bases and hydrogen bond donors, organic bases and nucleophilic anions, hydrogen bond donors and nucleophilic anions and active components and supports are highlighted. The challenge is to develop metal-free catalysts suitable for carbon dioxide capture and fixation. The ultimate goal is to synthesize cyclic carbonates in a flow reactor directly using carbon dioxide from industrial flue gas at ambient temperature and atmospheric pressure. By using synergetic effects, a multi-functional approach can meet the design strategy of metal-free catalysts for carbon dioxide adsorption and activation as well as epoxide ring opening.

切莫混用感冒药

感冒药的品种繁多,除中医按寒热虚实、阴阳表里理论创制的标本兼治的中成药外,市面上常有的西药品种就有几十种。这些药多数品种成分类似,作用也差异不大。所以,服用时一定要慎重,切不可超量服用或多药混用。

Synergistic action of non-solvent induced phase separation in preparation of poly(vinyl butyral) hollow fiber membrane via thermally induced phase separation

A systematic study of air gap distance effects on the structure and properties of poly(vinyl butyral)hollow fiber membrane via thermally induced phase separation(TIPS)has been carried out.The results show that the hollow fiber membrane prepared at air gap zero has no skin layer; the pore size near the outer surface is larger than that near the inner surface; and the special pore channel-like structure near the outer surface is formed,which is quite different with the typical sponge-like structure caused by TIPS and the finger-like structure caused by non-solvent induced phase separation(NIPS),because of the synergistic action of non-solvent induced phase separation at air gap zero.The pore size gradually decreases from outer surface layer to the intermediate layer,but increases gradually from intermediate layer to the inner surface layer.With the increase of air gap distance,the pore size near the outer surface gets smaller and a dense skin layer is formed,and the pore size gradually increases from the outer surface layer to the inner surface layer.Water permeability of the hollow fiber membrane decreases with air gap distance,the water permeability decreases sharply from 45.50×10-7 to 4.52×10-7 m3/(m2·s·kPa)as air gap increases from 0 to 10 mm at take-up speed of 0.236 m/s,further decreases from 4.52×10-7 to 1.00×10-8 m3/(m2·s·kPa)as the air gap increases from 10 to 40 mm.Both the breaking strength and the elongation increase with the increase of air gap distance.The breaking strength increases from 2.25 MPa to 4.19 MPa and the elongation increases from 33.9% to 132.6% as air gap increases from 0 mm to 40 mm at take-up speed 0.236 m/s.

Expression and correlation of Ezrin and survivin in non-small cell lung cancer

Objective: The aim of this study was to explore expression and correlation of Ezrin and survivin in non-small cell lung cancer (NSCLC). Methods: Expression of Ezrin and survivin were detected and analyzed by Envision method of immu- nohistochemical staining in 86 NSCLC. Results: The strong expression rate of Ezrin in NSCLC was 60.5% and significantly correlated with lymph node metastasis (P < 0.05), but no associated with gender, histologic subtype, TNM stages, differen- tiation and smoking. Meanwhile, the positive expression rate of survivin in NSCLC was 65.1% and significantly correlated with TNM stages and lymph node metastasis (P < 0.05), but no associated with gender, histologic subtype, differentiation and smoking. And expression of Ezrin and survivin were positively correlated in NSCLC (r = 0.384). Conclusion: Ezrin and survivin may play synergetic roles in the process of carcinogenesis of NSCLC, and their expression may be significantly associated with NSCLC metastasis. Detection of Ezrin and survivin may be valuable for diagnosing lung cancer metastasis and providing evidence for clinical treatment.

Design, synthesis and evaluation of novel non-ATP competitive CHK1 inhibitors as chemotherapy sensitizing agents

A series of urea-based compounds containing purine moieties were designed and synthesized as novel non-ATP competitive CHK1 inhibitors. The biological evaluation showed that several target compounds exhibited more potent inhibitory effects against CHK1 than the lead compound. In addition, one particular compound displayed synergistic effects with gemcitabine against HT29 cells.