Enhancement of uranium(VI) biomineralization by Saccharomyces cerevisiae through addition of inorganic phosphorus

Journal of Radioanalytical and Nuclear Chemistry - Enhancement of U(VI) biomineralization by Saccharomyces cerevisiae through addition of inorganic phosphorus was studied in this work. The addition...     

Two-dimensional Covalent Organic Frameworks: Intrinsic Synergy Promoting Photocatalytic Hydrogen Evolution

Covalent organic frameworks(COFs) are emerging photocatalysts for hydrogen evolution in water splitting in recent years. They offer a pre-designable platform to design tailor-made structures and chemically adjustable functionality in terms of photocatalysis. In this review, we summarize the recent striking progress of COF-based photocatalysts in design and synthesis. Firstly, different approaches to functionalizing building blocks, diversifying linkages, extending π-conjugation and establishing D-A conjugation are illustrated for enhancing photocatalytic activity. Next, post-modification of backbones and pores is detailed for emphasizing the synergistic catalytic uniqueness of COFs. Besides, the strategy of preparing COF-related composites with various semiconductors is outlined for optimizing the electronic properties. Finally, we conclude with the current challenges and promising opportunities for the exploration of new COF-based photocatalysts.     

Separation of five compounds from leaves of Andrographis paniculata (Burm. f.) Nees by off‐line two‐dimensional high‐speed counter‐current chromatography combined with gradient and recycling elution

An off‐line two‐dimensional high‐speed counter‐current chromatography method combined with gradient and recycling elution mode was established to isolate terpenoids and flavones from the leaves of Andrographis paniculata (Burm. f.) Nees. By using the solvent systems composed of n‐hexane/ethyl acetate/methanol/water with different volume ratios, five compounds including roseooside, 5,4′‐dihydroxyflavonoid‐7‐O‐β‐d ‐pyranglucuronatebutylester, 7,8‐dimethoxy‐2′‐hydroxy‐5‐O‐β‐d ‐glucopyranosyloxyflavon, 14‐deoxyandrographiside, and andrographolide were successfully isolated. Purities of these isolated compounds were all over 95% as determined by high‐performance liquid chromatography. Their structures were identified by UV, mass spectrometry, and ¹H NMR spectroscopy. It has been demonstrated that the combination of off‐line two‐dimensional high‐speed counter‐current chromatography with different elution modes is an efficient technique to isolate compounds from complex natural product extracts.     

2,6-二苯基苯酚及其聚合物的合成与应用进展

2,6-二苯基苯酚是一种重要的精细化工中间体,随着经济的发展和科学技术的不断进步,它及其聚合物的用量和用途都在不断扩大拓宽。本文主要介绍了近年来它及其聚合物不同的合成路线及其优缺点,对它们在吸附材料、工程塑料、抗氧化剂、气体分离膜等方面的应用研究进展进行了总结,并对它们的应用前景进行了展望。     

Fabrication of anisotropic silica hollow microspheres using polymeric protrusion particles as templates

Anisotropic polystyrene/poly(styrene-co-divinylbenzene) (PS/P(S-DVB)) protrusion particles with various morphologies such as eyeball-like, snowman-like, and raspberry-like were synthesized using a modified seeded polymerization method by dynamically controlling and stabilizing the phase separation. The effects of swelling agent, crosslinker, and monomer concentrations on the particle morphologies were studied. Using the PS/P(S-DVB) protrusion particles as templates, anisotropic silica (SiO₂) hollow microspheres were fabricated facilely. The obtained anisotropic silica hollow spheres had a potential application in rapid waste removal and detoxification extraction with a very simple procedure.     

Dual-beam coaxial amplification system of stimulated Brillouin scattering based on polarization control technology

In the field of Brillouin lidar, it has very important significance to find one method that can amplify the Brillouin scattering signal in real time. One new-type Brillouin lidar detection system based on Nd:YAG pulsed laser and polarization control device is designed in this paper. The key point of this detection system is to have two pulsed coherent lights with same frequency, same polarization and same initial phase, of which one beam is taken as the detection wave for generating stimulated Brillouin scattering signal and the other beam is taken as pumping wave for real time and effective amplification of stimulated Brillouin scattering signal. This detection system mainly includes two pulsed lasers and one electro-optical polarization controller. The laser is mainly used to obtain the pulsed lights with same frequency and same phase, and the polarization controller is mainly used to change the polarization state of two coaxial beams to make them change into same polarization state from orthogonal polarization state thus to enable the pumping wave to amplify the backward stimulated Brillouin scattering signal. It is shown from the experimental results that the adoption of this new system can realize the effect of pumping amplification and can increase the signal to noise ratio to a certain extent.     

Microenvironment Effects in Electrocatalysis: Ionic‐Liquid‐Like Coating on Carbon Nanotubes Enhances the Pd‐Electrocatalytic Alcohol Oxidation

A new catalyst consisting of ionic liquid (IL)‐functionalized carbon nanotubes (CNTs) obtained through 1,3‐dipolar cycloaddition support‐enhanced electrocatalytic Pd nanoparticles (Pd@IL(Cl^?)‐CNTs) was successfully fabricated and applied in direct ethanol alkaline fuel cells. The morphology, structure, component and stability of Pd@IL(Cl^?)‐CNTs were systematic characterized by transmission electron microscopy (TEM), high‐resolution transmission electron microscopy (HRTEM), Raman spectra, thermogravimetric analysis (TGA) and X‐ray diffraction (XRD). The new catalyst exhibited higher electrocatalytic activity, better tolerance and electrochemical stability than the Pd nanoparticles (NPs) immobilized on CNTs (Pd@CNTs), which was ascribed to the effects of the IL, larger electrochemically active surface area (ECSA), and greater processing performance. Cyclic voltammograms (CVs) at various scan rates illustrated that the oxidation behaviors of ethanol at all electrodes were controlled by diffusion processes. The investigation of the different counteranions demonstrated that the performance of the IL‐CNTs hybrid material was profoundly influenced by the subtly varied structures of the IL moiety. All the results indicated that the Pd@IL(Cl^?)‐CNTs catalyst is an efficient anode catalyst, which has potential applications in direct ethanol fuel cells and the strategy of IL functionalization of CNTs could be available to prepare other carbonaceous carrier supports to enhance the dispersivity, stability, and catalytic performance of metal NPs as well.     

Target Syntheses of Two New Bivanadyl Capped Keggin Polyoxometalate Derivatives

Two new bivanadyl capped Keggin polyoxometalate-based inorganic–organic hybrid compounds, [M(2,2′-bipy)₂(H₂O)]₂[AsMo₁₂O₄₀(VO)₂]}(M = Co 1, Zn 2; bipy = bipyridine), have been synthesized under hydrothermal conditions by directly using Li₃[AsMo₁₂O₄₀] · nH₂O as starting materials. Single crystal X-ray analysis revealed that compounds 1 and 2 were isostructural, consisting of a neutral bivanadyl capped Keggin POMs bigrafted by [M(2,2′-bipy)₂(H₂O)]²⁺ fragments. Other characterizations by elemental analysis, IR spectra, XPS spectra, power X-ray diffraction and TG analysis were also described in the paper. The study of the electrochemical properties of compounds 1 and 2 exhibit similar redox behaviors, undergoing three two-electron reversible redox processes, and the electrocatalysis of 1 has also been studied in detail. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

ANALYSIS OF AN SI EPIDEMIC MODEL WITH NONLINEAR TRANSMISSION AND STAGE STRUCTURE

A disease transmission model of SI type with stage structure is formulated. The stability of disease free equilibrium, the existence and uniqueness of an endemic equilibrium, the existence of a global attractor are investigated.     

用库仑-莫尔屈服准则对厚壁球的极限分析

用库仑－莫尔屈服准则对厚壁球进行了极限分析。该分析能够较好地反映出考虑材料的拉压屈服强度不同而对结构极限承载能力的影响。结果表明,厚壁球的极限承载能力随坟拉比Ｋ的增大而增大。本文导出的公式,对于理论研究和工程设计都具有参考价值。