Primary study on the assay of superficial hydroxyl group content upon the solid polyvinyl alcohol

Polyvinyl alcohol is a multipurpose polymer, and there is abundant hydroxyl group on its surface. In this article, we first time attempted to assay the superficial hydroxyl group content on the solid polyvinyl alcohol (PVA-1799) with a degree of polymerization over 1700 and a degree of alcoholysis over 99.0%. The assay was carried out by two different titration systems. The results show: (1) the order of magnitude of superficial hydroxyl group content on its solid surface was about 3.8E-5 mol/cm2 by acylation system with single functional group reagent (acetic anhydride); while (2) the order of magnitude of superficial hydroxyl group content was about 1.4E-7 mol/cm2 by esterification system with bi-functional group reagent (Toluence 2,4-DiIsocyanate, TDI). The results would be useful to provide a quantitative reference when -OH on the solid PVA surface is intended to be utilized for surface modification for some application. Moreover, the results and their difference also offer us the knowledge of the surface modification efficiency.     

Ultrafast enzyme immobilization over large-pore nanoscale mesoporous silica particles

By finely tuning the TEOS/P123 molar ratio of the octane/water/P123/TEOS quadruple emulsion system and by controlling the synthesis conditions, an ultrafine emulsion system was isolated, under the confinement of which, nanoscale silica particles with ordered large mesopores (approximately 13 nm) have been successfully constructed; the obtained mesoporous silica particles have an unusual ultrafast enzyme adsorption speed and the amount of enzyme that can be immobilized is larger than that of conventional mesoporous silica, which has potential applications in the fast separation of biomolecules.     

Stereocontrolled synthesis of tricyclic fused oxazolidinone as antibacterial agent

Tricyclic fused oxazolidinone 3a and 3b have been synthesized as antibacterial agents in 12 and 11 steps respectively. The key intermediates 10a and 10b have been developed via opening of epoxide 9a and 9b and cyclization by the resulting oxygen anion attack.     

Towards a portable microchip system with integrated thermal control and polymer waveguides for real-time PCR

A novel real-time PCR microchip platform with integrated thermal system and polymer waveguides has been developed. The integrated polymer optical system for real-time monitoring of PCR was fabricated in the same SU-8 layer as the PCR chamber, without additional masking steps. Two suitable DNA binding dyes, SYTOX Orange and TO-PRO-3, were selected and tested for the real-time PCR processes. As a model, cadF gene of Campylobacter jejuni has been amplified on the microchip. Using the integrated optical system of the real-time PCR microchip, the measured cycle threshold values of the real-time PCR performed with a dilution series of C. jejuni DNA template (2 to 200 pg/microL) could be quantitatively detected and compared with a conventional post-PCR analysis (DNA gel electrophoresis). The presented approach provided reliable real-time quantitative information of the PCR amplification of the targeted gene. With the integrated optical system, the reaction dynamics at any location inside the micro reaction chamber can easily be monitored.     

Computational observation of enhanced solvation of the hydroxyl radical with increased NaCl concentration

Classical molecular dynamics simulations with many-body potentials were carried out to quantitatively determine the effect of NaCl salt concentration on the aqueous solvation and surface concentration of hydroxyl radicals. The potential of mean force technique was used to track the incremental free energy of the hydroxyl radical from the vapor, crossing the air-water interface into the aqueous bulk. Results showed increased NaCl salt concentration significantly enhanced hydroxyl radical solvation, which should significantly increase its accommodation on water droplets. This has been experimentally observed for ozone aqueous accommodation with increased NaI concentration, but, to our knowledge, no experimental study has probed this for hydroxyl radicals. The origin for this effect was found to be very favorable hydroxyl radical-chloride ion interactions, being stronger than those for water-chloride.     

Inedible mushrooms: a good source of biologically active substances

In the course of our investigation on biologically active substances from inedible mushrooms in Japan, Germany, and Vietnam, we studied the chemical constituents of 22 species belonging to five families: Scutigeraceae, Polyporaceae, Xylariaceae, Thelephoraceae, and Paxillaceae. Various types of chemical substances were purified and characterized based on the modern spectroscopic methods and also on chemical reactions. These metabolites have shown a broad activity in many biological systems, such as antimicrobial, nematicidal, inhibition of NO production, anti-human immunodeficiency virus, tumor necrosis factor-alpha, and antioxidant activities. These isolated metabolites did not only show interesting activities, but also are employed as chemical markers supported for chemosystematics of these families. This review paper deals with the chemical constituents of 22 species, their biological activities, and also a discussion on chemosystematics.     

含吡唑基查尔酮的[2+2]环加成反应研究

在氢氧化钾存在下,用4-甲酰基吡唑类化合物和取代苯乙酮发生反应得到含吡唑基查尔酮的[2+2]环加成产物,对其进行了波谱表征,并对其反应机理进行了讨论.     

A Facile Route to Aryl Boronates: Room‐Temperature,Copper‐Catalyzed Borylation of Aryl Halides with Alkoxy Diboron Reagents

A simple but effective copper‐catalyzed borylation of aryl halides, including electron‐rich and sterically hindered aryl bromides, with alkoxy diboron reagents occurs under mild conditions (see scheme). Preliminary DFT studies of the mechanism suggest that σ‐bond metathesis between a copper–boryl intermediate and the aryl halide generates the aryl boronate product.

     

Highly Ordered Mesoporous Carbon as Catalyst for Oxidative Dehydrogenation of Ethylbenzene to Styrene

Highly active, selective, and stable : Highly ordered mesoporous carbon without deposition of metal particles catalyzes the oxidative dehydrogenation of ethyl benzene to styrene. A high activity and selectivity as well as long catalytic stability when compared with activated carbon, is observed from this catalyst.