Strong Pauli paramagnetic effect in the upper critical field of KCa2Fe4As4F2

Recently, 12442 system of Fe-based superconductors has attracted considerable attention owing to its unique double-Fe As-layer structure. A steep increase in the in-plane upper critical field with cooling has been observed near the superconducting transition temperature, Tc, in KCa2Fe4As4F2 single crystals. Herein, we report a high-field investigation on upper critical field of this material over a wide temperature range, and both out-of-plane(H∥c, Hc2c) and in-plane(H∥ab, Hc2ab ) directions have been measured.A sublinear temperature-dependent behavior is observed for the out-of-plane Hc2c , whereas strong convex curvature with cooling is observed for the in-plane Hc2ab . Such behaviors could not be described by the conventional Werthamer-Helfand-Hohenberg(WHH) model. The data analysis based on the WHH model by considering the spin aspects reveals a large Maki parameter α=9,indicating that the in-plane upper critical field is affected by a very strong Pauli paramagnetic effect.     

A conditional symmetric memristive system with amplitude and frequency control

By introducing a memristor into a chaotic system with a single non-quadratic term and substituting an absolute value function for conditional symmetry, a unique chaotic system is constructed. Firstly, the system shares a special structure of symmetry and conditional symmetry. Secondly, the amplitude and frequency of the system variables can be rescaled by the applied memristor. Interestingly it gives a new case of attractor control namely partial amplitude control and global frequency control. At last, as a new regime of extreme multistability, the memristive system shows relatively simple bifurcation according to the initial condition. This new class of chaotic system has never been reported to the best of our knowledge.

     

Syntheses,crystal structures and properties of Cd(II) and Ag(I) complexes based on 2-p-methylphenyl-5-(2-pyridyl)-1,3,4-thiadiazole

Abstract

Complexes of [CdL₂(NO₃)₂]·1.5H₂O and [Ag₂(μ-L)₂(NO₃)₂] were synthesized by the reactions of 2-p-methylphenyl-5-(2-pyridyl)-1,3,4-thiadiazole (L) with Cd(NO₃)₂·4H₂O and AgNO₃, respectively. Their structures were determined by single crystal X-ray diffraction. The photophysical property and thermal stability were characterized by FT???IR, UV???Vis absorption, fluorescence, and thermogravimetric analysis (TGA). Both complexes belong to the triclinic system with space group p???1. The central metal of [CdL₂(NO₃)₂]·1.5H₂O has a distorted octahedral geometry [CdN₄O₂], while two central Ag(I) atoms of [Ag₂(μ-L)₂(NO₃)₂] exhibit distorted tetrahedral geometries [AgN₃O].     

A STUDY OF LOW CYCLE FATIGUE PROPERTIES OF MATERIALS BASED ON THE FUNNEL-SHEET SPECIMENS1)

根据能量等效方法,针对漏斗薄片试样,提出了关联Ramberg-Osgood 幂律参数、试样几何参数的载荷-位移半解析统一模型。采用有限元数值模拟,正、反向验证了该模型的有效性。在此基础上,提出了通过漏斗薄片试样低循环试验实现材料低周疲劳性能的预测方法。基于薄片试样低循环试验数据,完成了SS316L, N18及SAPH440 三种材料的低周疲劳性能预测,预测结果与标准试样试验结果具有良好的一致性。并利用该方法完成了N18与SAPH在不同温度条件下的低周疲劳性能预测。     

The Antibacterial Activity Mode of Action of Plantaricin YKX against Staphylococcus aureus

We aimed to evaluate the inhibitory effect and mechanism of plantaricin YKX on S. aureus. The mode of action of plantaricin YKX against the cells of S. aureus indicated that plantaricin YKX was able to cause the leakage of cellular content and damage the structure of the cell membranes. Additionally, plantaricin YKX was also able to inhibit the formation of S. aureus biofilms. As the concentration of plantaricin YKX reached 3/4 MIC, the percentage of biofilm formation inhibition was over 50%. Fluorescent dye labeling combined with fluorescence microscopy confirmed the results. Finally, the effect of plantaricin YKX on the AI-2/LuxS QS system was investigated. Molecular docking predicted that the binding energy of AI-2 and plantaricin YKX was −4.7 kcal/mol and the binding energy of bacteriocin and luxS protein was −183.701 kcal/mol. The expression of the luxS gene increased significantly after being cocultured with plantaricin YKX, suggesting that plantaricin YKX can affect the QS system of S. aureus.     

Liquid chromatography-mass spectrometry identification of imidacloprid photolysis products

Photolysis of imidacloprid by near ultraviolet (UV) radiation was investigated using reversed phase liquid chromatography (RPLC) and liquid chromatography-electrospray ionization/mass spectrometry (LC-ESI/MS) operated in the positive ion mode. The decomposition of imidacloprid by near UV light is first order with a half life of 10.18 h. Photo-degradation products of imidacloprid identified in this study included imidacloprid urea, imidacloprid olefin, and imidacloprid desnitro. A degradation pathway is proposed for imidacloprid from an examination of the product decay curves obtained in this monitoring study which was performed in a batch test mode.     

Novel facile detection of persistent organic pollutants using highly sensitive gas sensor

Persistent organic pollutants (POPs) are greatly noxious chemicals in environment, and they can cumulate in organisms and transfer between different species. Therefore, it is significant to detect POPs for both environmental evaluation and further treatment. However, developing facile approach for the detection of POPs still remains a challenge so far. In this paper, we report an innovative method for facile detection of POPs using gas sensor for the first time. Porous SnO₂ nanostructures with a special tri-walled structure prepared via hydrothermal route and annealing process, were employed as gas-sensing materials. Through gas measurements, it was revealed that the as-fabricated gas sensor exhibited highly sensitive performance towards target POPs, including methoxychlor, mirex, p,p′-DDT, and aldrin. Moreover, we found that target POPs were distinguishable by extracting characteristics in kinetic curves of gas adsorption-desorption. As the presented detecting approach is facile without the requirements of complex operations, expensive and bulky instruments, it is expected that it would be developed as a promising method for the detection of POPs, and thereby showing its significance for environmental monitoring.     

Structure of aqueous sodium metaborate solutions: X-ray diffraction study

A structural analysis of aqueous sodium metaborate solutions (NaBo₂ · nH₂O, n = 10, 15, 20) at 298 ± 0.5 K by a rapid liquid ??-?? X-ray diffractometry with a highly effective X??celerator detector is reported in present paper. The radial distribution functions (RDF) and theoretical partial radial distribution functions for B-O, O-O, Na-O, Na-B, and Na-Na atom pairs were obtained from precisely diffraction data processing. Structure of aqueous sodium metaborate solutions was given through model calculation and described in three different items: hydrated sodium ion, hydrated metaborate ion and ion association. Effects of concentration on the structure of the solutions were discussed in detail. The mechanisms of ion aggregation and the formation of crystal nuclei in the solution are proposed. The results show that a clear picture of the structure of aqueous sodium metaborate solution has been acquired.