Affinity Labelling at the 4-Hydroxyl Group of N-Acetylglucosamine and N-Acetylgalactosamine

Derivatives of N-acetylgalactosamine and N-acetylglucosamine in which the 4-OH group could be selectively labelled have been prepared from a common precursor.     

Spherically Averaged Endpoint Strichartz Estimates For The Two­Dimensional Schrödinger Equation

The endpoint Strichartz estimates for the Schrödinger equation is known to be false in two dimensions[7]. However, if one averages the solution in L2 in the angular variable, we show that the homogeneous endpoint and the retarded half­endoint estimates hold, but the full retarded endpoint fails. In particular, the original verisions of these estimates hold for radial data     

Ionic liquid promoted preparation of 4H-thiopyran and pyrimidine nucleoside-thiopyran hybrids through one-pot multi-component reaction of thioamide

One-pot multi-component reactions of aldehydes, cyanothioacetamide and malononitrile promoted by ionic liquid proved to be an efficient way for the synthesis of thiopyran derivatives. Without any added catalyst, both aromatic and aliphatic aldehydes participated in this reaction smoothly. As an application of this method, a pyrimidine nucleoside-thiopyran chimera with potential biological activities was obtained in high yield from 5-formyl-2’-deoxyuridine. In addition, the ionic liquid used can be easily recovered and effectively reused for at least 5 times. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Improving dispersion and integration of single‐walled carbon nanotubes in epoxy composites by using a reactive noncovalent dispersant

Uniform dispersion and strong interfacial interaction are two critical prerequisites for application of single‐walled carbon nanotubes (SWNTs) in polymer composites. To endow the composites with multifunctional feature, no damage on the chemical/electronic structure of SWNTs is also usually required. With these ends in view, two epoxide‐containing pyrene derivatives (EpPys) were designed, synthesized, and used as reactive noncovalent dispersants for developing multifunctional epoxy/SWNT composites. One having longer chain length between epoxide group and pyrene moiety, that is, EpPy‐16, shows higher dispersing efficiency and provides the nanotube dispersion with better stability, thus picking up for subsequent studies. Systematic characterization on SWNT/EpPy‐16 hybrid demonstrates that 13.2 wt % of EpPy‐16 is adsorbed on the SWNT surface through strong π‐stacking interaction, and intrinsic electronic structure of SWNTs is basically reserved. The solution‐based process adopted here preserves the good SWNT dispersing state in dispersion into the composites. Simultaneously, enhanced interfacial interaction is also realized by using EpPy‐16, which interacts noncovalently with SWNT but connects covalently to epoxy network. As a result, the composites acquire 37 and 22% increments in tensile strength and Young's modulus, respectively, relative to that of neat resin. A low‐electrical percolation threshold of 0.1 wt % SWNTs and improved thermal properties were also observed. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis and applications of low‐bandgap conjugated polymers containing phenothiazine donor and various benzodiazole acceptors for polymer solar cells

A series of soluble donor‐acceptor conjugated polymers comprising of phenothiazine donor and various benzodiazole acceptors (i.e., benzothiadiazole, benzoselenodiazole, and benzoxadiazole) sandwiched between hexyl‐thiophene linkers were designed, synthesized, and used for the fabrication of polymer solar cells (PSC). The effects of the benzodiazole acceptors on the thermal, optical, electrochemical, and photovoltaic properties of these low‐bandgap (LBG) polymers were investigated. These LBG polymers possessed large molecular weight (M_n) in the range of 3.85?5.13 × 10⁴ with high thermal decomposition temperatures, which demonstrated broad absorption in the region of 300?750 nm with optical bandgaps of 1.80?1.93 eV. Both the HOMO energy level (?5.38 to ?5.47 eV) and LUMO energy level (?3.47 to ?3.60 eV) of the LBG polymers were within the desirable range of ideal energy level. Under 100 mW/cm² of AM 1.5 white‐light illumination, bulk heterojunction PSC devices containing an active layer of electron donor polymers mixed with electron acceptor [6,6]‐phenyl‐C₆₁‐butyric acid methyl ester (PC₆₁BM) or [6,6]‐phenyl‐C₇₁‐butyric acid methyl ester (PC₇₁BM) in different weight ratios were investigated. The best performance of the PSC device was obtained by using polymer PP6DHTBT as an electron donor and PC₇₁BM as an acceptor in the weight ratio of 1:4, and a power conversion efficiency value of 1.20%, an open‐circuit voltage (V_oc) value of 0.75 V, a short‐circuit current (J_sc) value of 4.60 mA/cm², and a fill factor (FF) value of 35.0% were achieved. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

任意维欧氏空间的长程势多极展开

给出了在任意维欧氏空间中一个一般的长程相互作用势的多极展开结果,并推导得到了单极子和偶极子两两之间的相互作用力公式.     

High selectively oxidative bromination of toluene derivatives by the H_2O_2-HBr system

An aqueous solution of hydrogen peroxide and hydrogen bromide illuminated by a 60 W incandescent light bulb serves as a source of bromine radicals.Various substituted toluenes（NO₂,Cl,Br,H,CH₃） were high selectively brominated at the benzyl position for monobromination in CH₂C1₂ at ice water with catalyst free.This simple but effective bromination of toluene derivatives with an aqueous H₂O₂-HBr system is characterized with the use of inexpensive reagents and a lower impact on the environment, which make it a good alternative to the existing bromination methods.     

REGULARITY CRITERIA FOR WEAK SOLUTION TO THE 3D MAGNETOHYDRODYNAMIC EQUATIONS＊

In this article,regularity criteria for the 3D magnetohydrodynamic equations are investigated.Some sufficient integrability conditions on two components or the gradient of two components of u + B and u...     

Infrared sensitivity of unstable vacua

We discover that some unstable vacua have long memory. By that we mean that even in the theories containing only massive particles, there are correllators and expectation values which grow with time. We examine the cases of instabilities caused by the constant electric fields, expanding and contracting universes and, most importantly, the global de Sitter space. In the last case the interaction leads to a remarkable UV/IR mixing and to a large back reaction. This gives reasons to believe that the cosmological constant problem could be resolved by the infrared physics.