Rational Design of Two-Dimensional Magnetic Chromium Borides Based on First-Principles Calculation

Two-dimensional(2D) magnetic materials have been experimentally recognized recently,however,the Curie temperatures(TC) of known 2D systems are quite low.Generally,magnetic systems can be seen as constituent magnetic elements providing spins and the non-magnetic elements providing frameworks to host the magnetic elements.Short bond lengths between the magnetic and non-magnetic elements would be beneficial for strong magnetic interactions and thus high TC.Based on this,we propose to combine the magnetic element Cr and the non-magnetic element boron to design novel 2D magnetic systems.Using our self-developed software package IM2 ODE,we design a series of chromium-boride based 2D magnetic materials.Nine stable magnetic systems are identified.Among them,we find that CrB4-Ⅰ,CrB4-Ⅱ and CrBs-Ⅰ with common structural units [CrB8] are ferromagnetic metals with estimated TC of 270 K,120 K and 110 K,respectively.On the other hand,five CrB3 phases with structural units [Cr2B12] are antiferromagnetic metals.Additionally,we also find one antiferromagnetic semiconductor CrB2-Ⅰ.Our work may open new directions for identifying 2D magnetic systems with high TC.     

High-efficient surface tailoring via reverse atom transfer radical polymerization and reversible addition-fragmentation chain-transfer polymerization in an aqueous system initiated by a monocenter redox pair

The commonly used multi-center initiation methods always lead to the formation of quantities of homopolymer in the surface tailoring based on reverse atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain-transfer (RAFT) polymerization. In this study, a monocenter redox pair constructed of silica bearing tert-butyl hydroperoxide groups and ascorbic acid (SiO₂-TBHP/AsAc) was applied to substitute the commonly used initiation method of R-supported RAFT grafting polymerization. All the propagating radicals were restricted on the surface of solid particles during the whole procedure theoretically, resulting in a higher grafting efficiency of 95.1% combined with the “controllable” feature at 10 h. This redox pair was also used to initiate the reverse ATRP in miniemulsion successfully with a grafting efficiency of 86.3% at 10 h. The grafting efficiency obtained under this monocenter initiation method was significantly higher than that of the frequently reported surface modification by reverse ATRP and RAFT polymerization. In addition, the high-efficient surface tailoring was traced and confirmed by nuclear magnetic resonance, Fourier transform infrared, X-ray photoelectron spectroscopy, thermogravimetric analysis, transmission electron microscopy, and other analysis tests. The advantage of this monocenter redox pair will open a new avenue for the potential “high-efficient” surface tailoring of various materials.     

磷酸酯类前药的合成方法与应用

磷酸酯类前药与原药相比,不仅能够提高药物靶向性、稳定性和生物利用度,减少药物毒副作用,还能掩蔽药物不适气味、提高水溶性从而改善给药途径。含羟基药物的磷酸酯化是该类药物前药设计的重要方法之一。本文根据中心磷原子的价态和化合物结构进行分类,综述了各种P(Ⅴ)四配位分子、P(Ⅲ)三配位分子和H-亚磷酸酯类化合物作为磷酸酯化试剂在磷酸酯类前药合成方法中的研究进展,并阐述了这些磷酸酯类药物的应用,最后总结了各类磷酸酯化试剂的优势与局限,并结合连续流反应技术应用案例展望了其发展趋势。     

Theoretical study of (e,2e) triple differential cross sections of pyrimidine and tetrahydrofurfuryl alcohol molecules using multi-center distorted-wave method

We report theoretical studies of electron impact triple differential cross sections of two bio-molecules,pyrimidine and tetrahydrofurfuryl alcohol,in the coplanar asymmetric kinematic conditions with the impact energy of 250 eV and ejected electron energy of 20 eV at three scattering angles of-5°,-10°,and-15°.Present multi-center distorted-wave method well describes the experimental data,which was obtained by performing(e,2e)experiment.The calculations show that the secondary electron produced by the primary impact electron is strongly influenced by the molecular ionic multi-center potential,which must be considered when the low energy electron interacts with DNA analogues.     

Design and exploration of 5-nitro-3-trinitromethyl-1H-1,2,4-triazole and its derivatives as energetic materials

Molecular Diversity - According to the fact that 5-nitro-3-trinitromethyl-1H-1,2,4 triazole (NTNMT) is a successful, good explosive, energetic groups such as –CH3, –NH2, –NHNO2,...     

Optimal Control of Nonlinear Fractional-Order Systems with Multiple Time-Varying Delays

Journal of Optimization Theory and Applications - This paper considers an optimal control problem governed by nonlinear fractional-order systems with multiple time-varying delays and subject to...     

A fully portable microchip real‐time polymerase chain reaction for rapid detection of pathogen

Point‐of‐care detection for pathogen is of critical need for wide epidemic warning and medical diagnosis. In this work, we have designed and developed a fully portable and integrated microchip based real‐time polymerase chain reaction machine for rapid pathogen detection. The instrument consists of three functional components including heating, optical, and electrical modules, which are integrated into a portable compact box. The microchip is consumable material replaceable to meet various detection needs. Consequently, we demonstrated the outstanding performance of this portable machine for rapid detection of Salmonella and Escherichia coli O157:H7 with the advantage of time‐saving (～25 min), less samples consumption, portability, and user‐friendly operation.     

Rapid Detection of AIB1 in Breast Cancer Cells Based on Aptamer-Functionalized Nanomotors

Herein, we report ultrasound-propelled graphene-oxide coated gold nanowire motors, functionalized with fluorescein-labeled DNA aptamers (FAM-AIB1-apt), for qualitative detection of overexpressed AIB1 oncoproteins in MCF-7 breast cancer cells. The movement of nanomotors under the ultrasound field facilitated intracellular uptake and resulted in a faster aptamer binding with the target protein and thus faster fluorescence recovery. The propulsion behavior of the aptamer functionalized nanomotors greatly enhanced the fluorescence intensity compared to static conditions. The new aptamer@nanomotor-based strategy offers considerable potential for further development of sensing methodologies towards diagnosis of breast cancer.     

Preparation of a monolithic column with a mixed‐mode stationary phase of reversed‐phase/hydrophilic interaction for capillary liquid chromatography

A monolithic capillary column with a mixed‐mode stationary phase of reversed‐phase/hydrophilic interaction chromatography was prepared for capillary liquid chromatography. The monolith was created by an in‐situ copolymerization of a homemade monomer N,N‐dimethyl‐N‐acryloxyundecyl‐N‐(3‐sulfopropyl) ammonium betaine and a crosslinker pentaerythritol triacrylate in a binary porogen agent consisting of methanol and isopropanol. The functional monomer was designed to have a highly polar zwitterionic sulfobetaine terminal group and a hydrophobic long alkyl chain moiety. The composition of the polymerization solution was systematically optimized to permit the best column performance. The columns were evaluated by using acidic, basic, polar neutral analytes, as well as a set of alkylbenzenes and Triton X100. Very good separations were obtained on the column with the mixed‐mode stationary phase. It was demonstrated that the mixed‐mode stationary phase displayed typic dual retention mechanisms of reversed‐phase/hydrophilic interaction liquid chromatography depending on the content of acetonitrile in the mobile phase. The method for column preparation is reproducible.