Recent Advances for Selective Catalysis in Benzene Methylation: Reactions,Shape-Selectivity and Perspectives

Catalysis Surveys from Asia - Benzene methylation over zeolite offers an alternative route to produce high-value toluene or para-xylene directly from benzene and C1 chemical sources, especially for...     

Electroplating silver tetracyanoquinodimethane between gold micro-gap electrodes for the fabrication of coplanar devices, a new way to integrate material synthesis and devices fabrication within one step

In this paper we propose a method for the integration of the synthesis of silver-tetracyanoquinodimethane (AgTCNQ) and the fabrication of its devices within one step. The method was performed by electroplating Ag between gold coplanar micro-gap electrodes in tetracyanoquinodimethane (TCNQ) solution. As soon as silver was electrochemically dissolved in the TCNQ solution, it immediately reacted with TCNQ to form AgTCNQ and then deposited between Au gap electrodes. With the continuing of the reaction, the Au micro-gap electrodes were connected by AgTCNQ to form Au/AgTCNQ/Au coplanar gap devices. With this electroplating technique, series gap devices of AgTCNQ were fabricated, and the devices exhibited switching phenomena with good reproducibility. This method integrated the synthesis of AgTCNQ and the fabrication of its devices within a single step, and should be also inspirable for other charge transfer complexes. PACS 81.05.Hd; 81.20.Ka; 82.45.Aa; 82.45.Qr     

Distributionally robust discrete optimization with Entropic Value-at-Risk

We study the discrete optimization problem under the distributionally robust framework. We optimize the Entropic Value-at-Risk, which is a coherent risk measure and is also known as Bernstein approximation for the chance constraint. We propose an efficient approximation algorithm to resolve the problem via solving a sequence of nominal problems. The computational results show that the number of nominal problems required to be solved is small under various distributional information sets.     

A new morphology of copper 7,7,8,8-tetracyano-p-quinodimethane

Morphology control is a long-standing problem that needs to be solved for making the switching mechanism of copper 7,7,8,8-tetracyano-p-quinodimethane (CuTCNQ) understood all the time, but up till now how many morphologies CuTCNQ possesses and which morphology should be responsible for the on/off switching phenomenon are still unclear. A new morphology of CuTCNQ, namely the tubular structure, has been obtained and characterized in our experiment, whose formation mechanism has also been investigated. Through characterizing, we can conclude that the tubular structure belongs to the phase I, which can be further confirmed by the electrical measurements. From the I-V plots, the carrier mobility of the tubular structure is estimated to be approximately 0.1 cm2 V-1 s-1, which suggests the potential application of CuTCNQ in devices.     

Potent and selective inhibition of T-cell protein tyrosine phosphatase (TCPTP) by a dinuclear copper(II) complex

A dinuclear Cu(II) complex, [Cu(2)(μ-IDA)(phen)(3)(NO(3))]NO(3)·4H(2)O (phen = 1,10-phenanthroline, H(2)IDA = iminodiacetic acid), was found to potently and selectively inhibit T-cell protein tyrosine phosphatase, and lead to the anti-proliferation and apoptosis of C6 glioma cells.     

Controlling the growth of single crystalline nanoribbons of copper tetracyanoquinodimethane for the fabrication of devices and device arrays

In this paper, (1) a simple and controllable method to synthesize single crystalline nanoribbons of CuTCNQ in a large area was demonstrated by using a physical and chemical vapor combined deposition technique. (2) Nanoribbons synthesized by this method were identified to belong to phase I. (3) Devices and device arrays of nanoribbons were in situ fabricated by this method using gap electrodes and gap electrode arrays. (4) Current-voltage characteristics of crystalline devices and device arrays of nanoribbons exhibited semiconductor properties, and this conclusion was further confirmed by the results of devices based on an individual nanoribbon or microribbon of CuTCNQ (phase I). The controllable synthesis of nanoribbons for the in situ fabrication of crystalline nanodevices and device arrays will be attractive for nanoelectronics. Moreover, semiconductor current-voltage characteristics of the nanoribbons will be beneficial to the understanding of CuTCNQ.     

Lanthanum Chloride Promoted Proliferation with Enhanced S‐phase Entry and Inhibited Potassium Currents of NIH 3T3 Cells

The effects of La³⁺ on proliferation, cell cycles, apoptosis and ion channels were investigated in mouse embryo fibroblast NIH 3T3 cells and its possible mechanisms were explored. Our data showed that La³⁺ promoted cell proliferation with increased S‐phase entry and inhibited the outward potassium currents in a concentration‐dependent manner in NIH 3T3 cells. La³⁺ and Ca²⁺ had synergistic effect on cell proliferation and cell cycles. It showed that Ca²⁺ was needed for La³⁺‐promoted cell cycle progression. Using the whole‐cell voltage‐clamp technique, we found that La³⁺ blocked the outward potassium current in a concentration‐dependent manner in NIH 3T3 cells. Lanthanum ions can increase intracellular Ca²⁺ concentration through inhibition of potassium currents, which induce a series of physiological changes and improve proliferation of cells. This may be one of the molecular mechanisms of lanthanum ions induced cell proliferation. The present work provides a new perspective for understanding the biological and toxicological effects of lanthanum.     

甜茶苷的酶法制备及其对肝肠胃细胞的抑制作用

甜茶苷是一种自然界中含量稀少的甜味剂。 本实验从多种糖苷酶中筛选出一种来自Aspergillus niger的β-葡萄糖苷酶,用以特异性水解斯替夫苷而高通量制备甜茶苷。 最适条件下反应12 h后,甜茶苷的产率为90.4%,斯替夫苷的转化率达98.8%。 为了进一步考察甜茶苷的安全性并拓展其潜在的用途,实验考察了甜茶苷对人胃肠道和肝脏细胞的细胞毒性,即甜茶苷对3种正常细胞以及11种癌细胞生长的抑制效果。 实验结果表明,在250 μg/mL的质量浓度下,甜茶苷对正常人胃肠肝细胞无毒性;相同质量浓度下,甜茶苷对人体肝癌细胞BEL-7404的抑制率是5-氟尿嘧啶的30％。