Peptides-assisted charge transfers in proteins: relay mechanism and its controllability

This feature article addresses several novel aspects regarding the peptide-mediated charge migrations, including: i) radical exchanges with tunable radical types (σ-radical versus π-radical) and electron-transfer (ET)-channel-tunable cooperative proton-coupled ET (PCET) mechanism, including hydrogen-atom transfer (HAT), single ET-channel PCET, double ET channel PCET, and channel-type-tunable (σ-channel versus π-channel) PCET; ii) hole hopping migration between the active groups in the side-chains and its controllability; iii) hole hopping through stepping-stones via a solvated “hole” form; and iv) electron hopping through positively charged groups as stepping-stones via a solvated electron state. In particular, the controllability of the ET channels (pathways and types) and solvated-“hole”/“electron”-based relay mechanisms are mainly mentioned. Clearly, this is an important addition to the well-documented mechanisms for charge migration in proteins. In view of the complexity of protein charge migration, further exploration on details of the stepping-stone-based relay mechanisms, by considering the properties and structures of the redox active centers, their intercalators, and the real surroundings, is still needed.     

Chiral magnetic metal-organic frameworks of Mn(II) with achiral tetrazolate-based ligands by spontaneous resolution

The enantiomers of complex 1 (1a and 1b) have been obtained by spontaneous resolution upon crystallization in the absence of a chiral source. The enantiomeric nature of 1a and 1b was confirmed by circular dichroism (CD) spectra and theoretical investigation.     

Reaction mechanism of methanol decomposition on Pt‐based model catalysts: A theoretical study

The decomposition mechanisms of methanol on five different Pt surfaces, the flat surface of Pt(111), Pt‐defect, Pt‐step, Pt(110)(1 × 1), and Pt(110)(2 × 1), have been studied with the DFT‐GGA method using the repeated slab model. The adsorption energies under the most stable configuration of the possible species and the activation energy barriers of the possible elementary reactions involved are obtained in this work. Through systematic calculations for the reaction mechanism of methanol decomposition on these surfaces, we found that such a reaction shows the same reaction mechanism on these Pt‐based model catalysts, that is, the final products are all H (H_ads) and CO (CO_ads) via O? H bond breaking in methanol and C? H bond scission in methoxy. These results are in general agreement with the previous experimental observations. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010.     

Redox‐induced configuration conversion for thioacetamide dimer can function as a molecular switch

The electronic switching properties of thioacetamide dimer (TAD) were investigated using the nonequilibrium Green's function method combined with density functional theory for design of a novel molecular switch. The H‐bonded TAD can be converted upon hole‐trapping to a three‐electron (3e)‐bonded configuration with a S∴S linkage which could provide a more favorable channel for charge transfer than the before. The redox‐induced configuration conversion between the H‐bonded and the 3e‐bonded TADs could govern the charge migration through the molecular junction with a considerable difference in conduction currents. The calculated I–V characteristic curves of two configurations exhibit a switching behavior with an On‐Off ratio in a range of about 4.3–7.6 within the applied voltages. Clearly, this hypothetical scheme provides a potential way to explore the novel conformation‐dependent molecular switch. © 2010 Wiley Periodicals, Inc. J Comput Chem 2010     

一种新型毫米波矩形波导-微带过渡结构

介绍了一种新颖的、适用于毫米波频段的矩形波导-微带过渡电路结构。该过渡电路具有插入损耗低、频带宽、重复性好的特性。其矩形波导E面相对于微带电路面,以及电磁信号传输方向的位置与脊波导-微带过渡相同。该过渡电路的微带线与波导的转换部分采用非接触式结构,并设计了可调节元件,从而在有一定加工误差的条件下改善其产品传输特性。利用高频仿真软件CST,在Ka频段进行了优化仿真,并对利用其优化值所设计的一对背靠背的电路实物进行了测试,在32～40 GHz的频率范围内,插入损耗小于2.36 dB,回波损耗大于7.22 dB;在整个Ka频段内,插入损耗小于3.49 dB。     

Bounds on an anomalous dijet resonance in W+jets production in pp collisions at √s = 1.96 TeV

We present a study of the dijet invariant mass spectrum in events with two jets produced in association with a W boson in data corresponding to an integrated luminosity of 4.3 fb(-1) collected with the D0 detector at √s = 1.96 TeV. We find no evidence for anomalous resonant dijet production and derive upper limits on the production cross section of an anomalous dijet resonance recently reported by the CDF Collaboration, investigating the range of dijet invariant mass from 110 to 170 GeV/c(2). The probability of the D0 data being consistent with the presence of a dijet resonance with 4 pb production cross section at 145 GeV/c(2) is 8×10(-6).     

Characterization and activity of visible-light-driven TiO2 photocatalyst codoped with lanthanum and iodine

The novel visible-light-activated La/I/TiO₂ nanocomposition photocatalyst was successfully synthesized using precipitation-dipping method, and characterized by X-ray powder diffraction (XRD), the Brunauer-Emmett-Teller (BET) method, transmission electron microscopy (TEM), thermogravimetry-differential scanning calorimetry (TG-DSC) and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The photocatalytic activity of La/I/TiO₂ was evaluated by studying photodegradation of reactive blue 19 as a probe reaction under simulated sunlight irradiation. Photocatalytic experiment results showed that the maximum specific photocatalytic activity of the La/I/TiO₂ photocatalyst appeared when the molar ratio of La/Ti was 2.0 at%, calcined at 350 °C for 2 h, due to the sample with good crystallization, high BET surface area and small crystal size. Under simulated sunlight irradiation, the degradation of reactive blue 19 aqueous solution reached 98.6% in 80 min, which showed La/I/TiO₂ photocatalyst to be much higher photocatalytic activity compared to standard Degussa P25 photocatalyst. The higher visible light activity is due to the codoping of lanthanum and iodine.     

Theory of modified thermally stimulated current and direct determination of trap level distribution

In order to investigate the trap level distribution in polymer films, a new method is proposed based on modified thermally stimulated current (TSC) theory and numerical calculation of the TSC measurement. In this method, a new function is defined to weight the contribution of every trap level to the external current. The demarcation energy is used to study the trap emptying process. The modified TSC theory shows that only the electrons with trap levels very close to the demarcation energy can significantly contribute to the external circuit at any instant temperature. Based on this method, the trap level distribution of the DuPont original polyimide film 100HN and nanocomposite polyimide film 100CR are investigated as an application example. The effectiveness of the method is confirmed by the experiments. The experimental results show that the trap level density in the 100CR PI films is about six times larger than that in the 100HN PI films through the investigated trap level ranges 06–1.3 eV. The increased traps in 100CR should be introduced by nanofillers, probably come from the interfaces formed between nanofillers and the polymer matrix.     

Main Q-eigenvalues and generalized Q-cospectrality of graphs

Let Q ^G denote the signless Laplacian matrix of a graph G. An eigenvalue μ of Q ^G is said to be a main Q-eigenvalue of G if μ has an eigenvector which is not orthogonal to an all-ones vector e. We give some basic properties of main Q-eigenvalues. For a graph G of order n, G is called Q-controllable if G has n distinct main Q-eigenvalues. We show that a graph H is generalized Q-cospectral with a Q-controllable G if and only if H is Q-controllable and there exists a unique rational orthogonal matrix R such that R _e = e, Q _H = R ^? Q _G R.