Hydrogenated silicene based magnetic junction with improved tunneling magnetoresistance and spin-filtering efficiency

In this paper, hydrogenation is used for the generation of band gap in silicene and the hydrogenated silicene is then studied for its spintronic application. Upon hydrogenation, silicene transforms into a wide band gap material with a band gap of 3.32 eV. Parameters like magneto-resistance and spin-filtering efficiency of magnetic tunnel junction (MTJ) with CrO₂ as semi-metallic electrodes and hydrogenated silicene as scattering region are found to increase compared to pristine silicene as scattering region. The simulation results show that the magneto-resistance of hydrogenated silicene remains above 85% (higher than the pristine counterpart) for the entire bias range. In addition, the spin-filtering efficiency in hydrogenated silicene reaches a value as high as 96% whereas in case of pristine silicene it remains below 90% for the entire bias range.     

Exploring Effects of Chitosan Oligosaccharides on the DSS-Induced Intestinal Barrier Impairment In Vitro and In Vivo

Intestinal barrier dysfunction is an essential pathological change in inflammatory bowel disease (IBD). The mucus layer and the intestinal epithelial tight junction act together to maintain barrier integrity. Studies showed that chitosan oligosaccharide (COS) had a positive effect on gut health, effectively protecting the intestinal barrier in IBD. However, these studies usually focused on its impact on the intestinal epithelial tight junction. The influence of COS on the intestinal mucus layer is still poorly understood. In this study, we explored the effect of COS on intestinal mucus in vitro using human colonic mucus-secreted HT-29 cells. COS relieved DSS (dextran sulfate sodium)-induced mucus defects. Additionally, the structural characteristics of COS greatly influenced this activity. Finally, we evaluated the protective effect of COS on intestinal barrier function in mice with DSS-induced colitis. The results indicated that COS could manipulate intestinal mucus production, which likely contributed to its intestinal protective effects.     

The Ideal Ionic Liquid Salt Bridge for the Direct Determination of Gibbs Energies of Transfer of Single Ions,Part I: The Concept

Described is a procedure for the thermodynamically rigorous, experimental determination of the Gibbs energy of transfer of single ions between solvents. The method is based on potential difference measurements between two electrochemical half cells with different solvents connected by an ideal ionic liquid salt bridge (ILSB). Discussed are the specific requirements for the IL with regard to the procedure, thus ensuring that the liquid junction potentials (LJP) at both ends of the ILSB are mostly canceled. The remaining parts of the LJPs can be determined by separate electromotive force measurements. No extra‐thermodynamic assumptions are necessary for this procedure. The accuracy of the measurements depends, amongst others, on the ideality of the IL used, as shown in our companion paper Part II.     

一维TiO2锐钛矿/金红石异相结的制备及光催化降解甲醛性能

TiO₂异相结主要通过高温方法制备,所制备材料的形貌和组成较难控制,尤其是在较低温度下一步制备一维TiO₂异相结仍具有一定的挑战性。采用简单、方便的一步水热法,在较低温度下(180℃)制备了一维纳米TiO₂异相结材料。X射线衍射(XRD)和高分辨透射电镜(HRTEM)分析表明,制备的材料以一维金红石相TiO₂纳米棒(长度：(400±50) nm,直径：(60±5) nm)为基本结构,粒径分布均匀的锐钛矿相TiO₂纳米粒子(直径：(9.5±0.5) nm)高密度、单分散地负载在纳米棒上。通过控制水热反应时间成功调控了异相结中锐钛矿相TiO₂的含量(20%～50%),进而实现了其光催化降解HCHO性能的调控。实验结果表明,当锐钛矿相TiO₂的含量为33%时(TiO₂-24,水热时间24 h制备的样品),异相结光催化剂表现出最佳的HCHO降解性能：在低光强LED灯(波长为365 nm,光强为12.26 mW·cm     

发光二极管放电实验现象分析

利用直流电源对发光二极管(LED)的结电容充电,切断直流电源后对LED的电压-时间特性进行测量。当充电电压低于LED复合发光的门槛电压,LED的电压-时间特性与普通二极管的相似。当充电电压高于LED复合发光的门槛电压,首次观察到:开始放电的瞬间会出现一个快速下降过程,快速下降到门槛电压以下;LED上的电压越高,快速下降到的电压越低。对该现象进行分析,得到一些新的结论。当LED的正偏电压高于复合发光的门槛电压后,出现了注入到扩散区的非平衡载流子随正偏电压的提高而减小的现象,即dQ/du<0。     

Effect of thermal-annealing on the magnetoresistance of manganite-based junctions

Thermal-annealing has been widely used in modulating the oxygen content of manganites. In this work, we have studied the effect of annealing on the transport properties and magnetoresistance of junctions composed of a La0.9Ca0.1MnO3＋6 film and a Nb-doped SrTiO3 substrate. We have demonstrated that the magnetoresistance of junctions is strongly dependent on the annealing conditions： Prom the junction annealed-in-air to the junction annealedin-vacuum, the magnetoresistance near 0-V bias can vary from ～-60% to N～0. A possible mechanism accounting for this phenomenon is discussed.     

p-n结二极管结区边界附近的交流电特性

基于p-n结二极管的理想工作状态的基本假定，推导了二极管在交流电下工作时其基区和p-n结分界面附近上的时间常数与二极管空间尺寸、扩散长度、载流子寿命和外加交流电频率等的依赖关系.结果发现高频和低频两种状态下二极管各类特征参量对时间常数的作用不一样.低频条件下，二极管的时间常数由材料本身来决定，与外加电流频率无关.高频情况下，时间常数则与半导体材料性质无关，只由外加交流电的频率来决定.     

Tunneling magnetoresistance of the double spin-filter junctions at nonzero bias

A recent theoretical estimation indicated that the NM/FI/FI/NM double spin-filter junction (DSFJ, here the NM and FI represent the nonmagnetic electrode and the ferromagnetic insulator (semiconductor) spacer, respectively) could have very high tunneling magnetoresistance (TMR) at zero bias. To meet the requirement in research and application of the magnetoresistance devices, we have calculated the dependences of tunneling magnetoresistance of DSFJ on the bias (voltage), the thicknesses of ferromagnetic insulators (semiconductors) and the average barrier height. Our results show that except its very high value, the TMR of DSFJ does not decrease monotonously and rapidly with rising bias, but increase slowly at first and decrease then after having reached a maximum value. This feature is in distinct contrast to the ordinary magnetic tunnel junction FM/NI/FM (FM and NI denote the ferromagnetic electrode and the nonmagnetic insulator (semiconductor) spacer, respectively), and is of benefit to the use of DSFJ as a magnetoresistance device.     

Pseudoreceptor model for ryanodine derivatives at calcium release channels

This paper describes the generation of a pseudoreceptor model for ryanodine receptor (RyR) modulating ryanoids in rabbit skeletal muscle. For this purpose, the molecular modelling software PrGen was applied to correlate experimentally determined and calculated free energies of binding for a set of 15 ryanodine derivatives. The final model indicates a narrow cleft with hydrogen bond donor and acceptor capacities (represented by an Asn) as most crucial for binding the pyrrole carboxylate substituent at C3 of ryanodine. In addition, hydrophobic residues flank the aromatic pyrrole ring (Tyr, Phe, and Ile). Two of those residues (Tyr and Ile) interact with the 2-isopropyl moiety, which seems to contribute to binding. Opposite to the pyrrole locus, a second hydrophobic region (represented by a Leu) restricts ryanodine derivatives in their longitudinal axis and leads to the discrimination of equatorial and axial positioned methyl groups and of polar substituents at C9. Finally, a charged glutamate residue generates strong hydrogen bonding and electrostatic interactions with the hydroxyl groups at C10 and C15. For this binding-site model – composed of six amino acid residues – a correlation for the training set ligands of R = 0.99 (Q² = 0.975) and a root mean square (rms) deviation of 0.568 kcal/mol for the prediction of the binding energies of four test set ligands was obtained. Based on this pseudoreceptor model the putative topology of the real binding site of ryanoids will be discussed.