Polymeric ytterbium(ii) complex with pyridyl amido ligands

The reaction of potassium pyridyl amido ligand {L = [N(R)(2-C5H3N-6-Me)]–, R = CH2But} with YbI2(thf)2 afforded the linear polymeric complex [K0.5(L)3YbiiK0.5]n, which was characterized by X-ray structure analysis.     

Al高掺杂浓度对ZnO禁带和吸收光谱影响的第一性原理研究

采用密度泛函理论框架下的第一性原理平面波超软赝势方法, 建立了未掺杂与不同浓度的Al原子取代Zn原子的两种Zn_1-xAl_xO超胞模型,分别对模型进行了几何结构优化、态密度分布和能带分布的计算. 结果表明: ZnO高掺杂Al的条件下, 掺杂的Al原子浓度越大,间隙带越窄, 蓝移越弱. 计算结果和实验结果相一致.     

Photoelectrocatalytic decomposition of gaseous isopropanol in a polymer electrolyte photoreactor

A photoelectrochemical reactor constructed as a proton exchange membrane fuel cell was utilized to electrochemically enhance the photocatalytic decomposition of gas-phase isopropanol. Nafion membrane was employed to serve as solid electrolyte to establish an electrochemical circuit for the gaseous photocatalytic reaction. The electrical current density of photoanode was found to correspond to the variation of the applied bias and relative humidity of the inlet gas. Photocatalytic decomposition rate was remarkably increased by 20 % by applying a bias potential of 5 V. The effect of relative humidity exhibited multiple effects for membrane conductivity of Nafion and efficiency of photocatalytic decomposition reaction.     

Theoretical studies on selectivities in the Staudinger reaction of vicinal diimines and ketenes

The selectivities,including peri-,regio-,and diastereoselectivities,in the Staudinger reaction involving vicinal diimines and ketenes were investigated theoretically via the density functional theory(DFT) calculation.The results indicate that vicinal diimines prefer stepwise [2+2] cycloaddition rather than [2+4] cycloaddition to generate cis-4-imino-β-lactams.The diimines attack the less sterically hindered exo-side of ketenes to generate zwitterionic intermediates,which directly undergo a conrotatory ring closure to produce cis-4-imino-β-lactams whatever diimines with less or more bulky N-substituents.For unsymmetric vicinal ketoaldehyde-derived diimines,their ketimines attack the exo-side of ketenes and undergo a conrotatory ring closure to produce cis-4-aldimino-β-lactams due to less steric effect.The current theoretical studies provide very important information for in-depth understanding of the selective formation of mono-cis-β-lactams from vicinal diimines and ketenes.     

Improvement in Uranium Adsorption Properties of Amidoxime-Based Adsorbent Through Cografting of Amine Group

Amidoxime (AO)/amine co-functionalized polypropylene fiber adsorbents were prepared. The all-polymeric structures were characterized by using Fourier transform infrared spectroscopy (FTIR), optical microscope, contact angle meter and electron spin resonance (ESR) analysis methods, confirming the grafting, modification, and amidoximation stages gravimetrically, spectroscopically, and visually. The properties for the removal of uranyl(VI) from aqueous solutions were investigated. For amidoxime (AO) fiber, high adsorption rate was observed within the first 30 minutes and the plateau value of 40.6% uranium loading (0.0812 mg/g) was reached at around 30 minutes. The adsorption equilibrium for AO/amine fiber was attained within 20 minutes, resulting in the adsorption of 92.6% uranium loading (0.185 mg/g). The percentage of adsorption increases with increasing pH value (2–6), reaches a maximum at pH 6.0 and then remains almost constant for AO/amine fiber, whereas reduces slightly for AO fiber.     

A PEGylated Fluorescent Turn‐On Sensor for Detecting Fluoride Ions in Totally Aqueous Media and Its Imaging in Live Cells

Owing to the considerable significance of fluoride anions for health and environmental issues, it is of great importance to develop methods that can rapidly, sensitively and selectively detect the fluoride anion in aqueous media and biological samples. Herein, we demonstrate a robust fluorescent turn‐on sensor for detecting the fluoride ion in a totally aqueous solution. In this study, a biocompatible hydrophilic polymer poly(ethylene glycol) (PEG) is incorporated into the sensing system to ensure water solubility and to enhance biocompatibility. tert‐Butyldiphenylsilyl (TBDPS) groups were then covalently introduced onto the fluorescein moiety, which effectively quenched the fluorescence of the sensor. Upon addition of fluoride ion, the selective fluoride‐mediated cleavage of the Si? O bond leads to the recovery of the fluorescein moiety, resulting in a dramatic increase in fluorescence intensity under visible light excitation. The sensor is responsive and highly selective for the fluoride anion over other common anions; it also exhibits a very low detection limit of 19 ppb. In addition, this sensor is operative in some real samples such as running water, urine, and serum and can accurately detect fluoride ions in these samples. The cytotoxicity of the sensor was determined to be Grade I toxicity according to United States Pharmacopoeia and ISO 10993‐5, suggesting the very low cytotoxicity of the sensor. Moreover, it was found that the senor could be readily internalized by both HeLa and L929 cells and the sensor could be utilized to track fluoride level changes inside the cells.     

Using electrospray laser desorption ionization mass spectrometry to rapidly examine the integrity of proteins stored in various solutions

Electrospray laser desorption ionization mass spectrometry (ELDI/MS) allows the rapid desorption and ionization of proteins from solutions under ambient conditions. In this study, we have demonstrated the use of ELDI/MS to efficiently examine the integrity of the proteins stored in various solutions before they were further used for other biochemical tests. The protein standards were prepared in the solutions containing buffers, organic salts, inorganic salts, strong acid, strong base, and organic solvents, respectively, to simulate those collected from solvent extraction, filtration, dialysis, or chromatographic separation. Other than the deposit of a drop of the sample solution on the metallic sample plate in an ELDI source, no additional sample pretreatment is needed. The sample drop was then irradiated with a pulsed laser; this led to desorption of the analyte molecules, which subsequently entered the ESI plume to undergo post-ionization. Because adjustment of the composition of the sample solution is unnecessary, this technique appears to be useful for rapidly evaluating the integrity of proteins after storage or prior to further biochemical treatment. In addition, when using acid-free and low-organic-solvent ESI solutions for ELDI/MS analysis, the native conformations of the proteins in solution could be detected.

Sensitive detection of T4 polynucleotide kinase activity based on coupled exonuclease reaction and nicking enzyme-assisted fluorescence signal amplification

As a prominent member of the 5′-kinase family, T4 polynucleotide kinase (PNK) plays an important role in gene function regulations, and the study of PNK activity and its potential inhibitors is significant for research related to the DNA phosphorylation process. Here, we proposed a novel strategy for the detection of PNK activity and its inhibition, which combines exonuclease enzyme reaction and nicking enzyme-assisted fluorescence signal amplification. Through recycling cleavage of DNA fluorescence probe for signal amplification, a highly sensitive PNK sensing platform is developed, and a very low detection limit of 0.05 mU/mL is achieved, which is better than or comparable to that of the previously reported PNK assays. The present approach adopts a simple separation-free procedure in which the enzyme assay is conducted in homogeneous solutions. Additionally, the inhibitory effects of several known kinase inhibitors on PNK have been successfully detected. Since the proposed assay exhibits the advantages of high sensitivity and simplicity, it holds great potential in providing a promising platform for convenient and highly sensitive detection of PNK activity and its inhibitors.

基于MXenes的功能纤维的制备及其在智能可穿戴领域的应用

在电子信息和物联网技术的推动下,人类对可穿戴电子器件和智能织物的需求愈发突出,功能纤维作为智能可穿戴设备的重要载体,近年来获得快速发展。功能纤维的性能很大程度上取决于纤维的基础构筑单元。过渡金属碳/氮化物(MXenes)作为一种新兴的二维材料,凭借其高电导率、优异的可加工性能、可调节的表面特性以及出色的机械强度等优点,受到了极大的关注,也逐渐成为构筑功能纤维的重要单元。本文将主要综述MXenes的湿化学、熔融盐、无氟试剂刻蚀等方法和力学、电学、光学和化学稳定性等性能,阐述基于该材料制备的功能纤维在传感、储能以及其他智能领域的应用,最后讨论了基于MXenes材料的功能纤维的未来应用前景和技术挑战。