The Synthesis of Alanine Oligopeptides

The oligopeptides of alanine (penta-, deca-, and pentadeca-) were synthesized by solid phase method and new peptide-resin cleaving reagent TFA-BBr₃ was used to cleave the peptides from resin-support. Penta-alanine was also synthesized by liquid phase for the comparision and FAB-Mass method was used to determine the molecular weight of penta-alanine. HPLC separation of these new oligopeptides were described.     

气相单四极质谱(DSQTM Ⅱ)组合扫描技术用于多组分化合物的同时分析

当前气相单四极质谱已经被广泛的应用于如农药残留、环境检测等众多领域.全扫描(FS)和选择离子扫描(SIM)是单四极质谱中最为常用的两种模式.     

Novel selectfluor and deoxo-fluor-mediated rearrangements. New 5(6)-methyl and phenyl methanopyrrolidine alcohols and fluorides

Stereoselective syntheses of novel 5,6-difunctionalized-2-azabicyclo[2.1.1]hexanes containing 5-anti-fluoro or hydroxyl in one methano bridge and a variety of syn- or anti-chloro, fluoro, hydroxy, methyl, or phenyl substituents in the other methano bridge have been effected. Rearrangements of iodides to alcohols were initiated using Selectfluor. Rearrangement of alcohols to fluorides was initiated using Deoxo-Fluor. Ring opening of 2-azabicyclo[2.2.0]hex-5-ene exo-epoxide with organocopper reagents is regioselective at C(5).     

FIA-ICP/AES法分析茶叶浸取液中多元素的形态

本文报道了分析茶叶浸取液中[Zn、Mn、Fe、Al及Mg]形态的新方法。研究了以C-18柱为分离柱的流动注射与ICP/AES的联用技术。     

Sizable concentration-dependent frequency shifts in solution NMR using sensitive probes

With the growing use of high fields and ultrasensitive probes, radiation damping emerges as a significant feedback interaction in modern solution NMR. Motivated by recent observations of mysterious concentration-dependent frequency shifts, experiments carried out on a cryoprobe at 600 MHz have revealed a time-averaged frequency shift of up to +83/-81 Hz. The sizable frequency shifts arise from deviations in the phase of the radiation damping field from perfect orthogonality relative to the net transverse magnetization. The frequency shift is shown to depend on the longitudinal magnetization and probe tuning conditions through experiments and numerical simulations. Such unexpected shifts in the solvent precession frequency provide a physical explanation for the empirical practice of adjusting the irradiation frequency of the saturating B1 field in solvent presaturation to achieve optimal suppression. Additional applications of the radiation damping induced frequency shift to solvent suppression and NMR methodology are discussed.     

便携式温度计校验仪的研制

介绍便携式温度计校验仪的工作原理及研制过程。对该仪器的恒温槽体机械结构、制冷器和散热器的设计、恒温槽体温度测量及控制等进行了详细叙述。该仪器提供的温度场稳定、均匀，在-20～100℃范围内可任意设定温度。解决了温度计现场快速校准的问题。     

SYNTHETIC STUDIES ON BLOOD COMPATIBLE BIOMATERIALS 13:A NOVEL SEGMENTED POLYURETHANE CONTAINING PHOSPHORYLCHOLINE STRUCTURE:SYNTHESIS,CHARACTERIZATION AND BLOOD COMPATIBILITY EVALUATION

A new phosphorylcholine, (6-hydroxy) hexyl-2-(trimethylammonio) ethyl phosphate (HTEP), was synthesized andcharasterized. Segmented polyurethane (SPU) containing phosphorylcholine structure was synthesized based ondiphenylmethane diisocyanate (MDI), soft segment polytetramethylene glycol (PTMG) and HTEP, with 1,4-butanediol (BD)as a chain extender. The existence of phosphorylcholine structure on the surface of SPU was revealed by attenuated totalreflectance Fourier transform infrard spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and water contactangle measurements. The blood compatibilities of the polymers were evaluated by hemolytic testing and a platelet-richplasma (PRP) adhesion experiment, which was viewed by scanning electron microscopy (SEM) with polyurethane as areference. The novel segmented polyurethane containing phosphorylcholine structure showed improved blood compatibility.     

Studies on the identification and syntheses of insect pheromones XXI stereoselective synthesis of all the possible optical isomers of the mosquito oviposition attractant pheromone

All the four optical isomers of the oviposition attractant pheromone of the mosquito $\text{Gulex pipiens fatigans}$ were synthesized via Sharpless asymmetric epoxidation.     

Determination of metal additives and bromine in recycled thermoplasts from electronic waste by TXRF analysis

A new method for analysis of metal additives in recycled thermoplasts from electronic waste was developed, based on dissolving the samples in an organic solvent and subsequent analysis of the corresponding solutions or suspensions by total-reflection X-ray fluorescence spectroscopy (TXRF). The procedure proved to be considerably less time consuming than the conventional digestion of the polymer matrix. Additives containing Ti, Zn, Br, Cd, Sn, Sb, and Pb were analyzed in a hundred randomly selected samples from recycling, which provided an overview of the range of elemental concentrations in thermoplasts utilized for consumer electronics. The results were validated independently by instrumental neutron activation analysis (INAA), subsequent regression analysis confirmed the trueness of the chosen approach.     

H2/CO2 separations in multicomponent metal-adeninate MOFs with multiple chemically distinct pore environments

Metal–organic frameworks constructed from multiple (≥3) components often exhibit dramatically increased structural complexity compared to their 2 component (1 metal, 1 linker) counterparts, such as multiple chemically unique pore environments and a plurality of diverse molecular diffusion pathways. This inherent complexity can be advantageous for gas separation applications. Here, we report two isoreticular multicomponent MOFs, bMOF-200 (4 components; Cu, Zn, adeninate, pyrazolate) and bMOF-201 (3 components; Zn, adeninate, pyrazolate). We describe their structures, which contain 3 unique interconnected pore environments, and we use Kohn–Sham density functional theory (DFT) along with the climbing image nudged elastic band (CI-NEB) method to predict potential H₂/CO₂ separation ability of bMOF-200. We examine the H₂/CO₂ separation performance using both column breakthrough and membrane permeation studies. bMOF-200 membranes exhibit a H₂/CO₂ separation factor of 7.9. The pore space of bMOF-201 is significantly different than bMOF-200, and one molecular diffusion pathway is occluded by coordinating charge-balancing formate and acetate anions. A consequence of this structural difference is reduced permeability to both H₂ and CO₂ and a significantly improved H₂/CO₂ separation factor of 22.2 compared to bMOF-200, which makes bMOF-201 membranes competitive with some of the best performing MOF membranes in terms of H₂/CO₂ separations.

Tailorable multicomponent MOFs and MOF membranes for efficient H₂/CO₂ separation.