Cure kinetics of epoxy-amine resins used in the restoration of works of art from glass or ceramic

The cure kinetics of two epoxy/amine resins, Araldite 2020 and AY103-HY956 widely used as adhesives in the restoration of works of art from glass or ceramic was investigated using FTIR spectroscopy. These resins are two-part adhesives, consisting of a resin - A, based on a diglycidyl ether of bisphenol A, and a hardener - B which is either a cycloaliphatic amine (isophorone diamine) for Araldite 2020, or a mixture of three aliphatic amines in HY956. The study was based on the collection of IR spectra, in the middle range (4000-600 cm⁻¹), of mixtures of resin and hardener at different proportions and isothermal temperatures (22-70 °C) as a function of curing time. A kinetic model was employed to simulate the experimental data using two kinetic rate constants. Diffusion control was incorporated to describe the cure behaviour at high degrees of conversion. From fitting to experimental data the kinetic and diffusional parameters were estimated, together with the activation energies of the kinetic and autocatalytic rate constants. It was found that higher degrees of curing are obtained at higher temperatures and increased amounts of hardener. Differences in the performance of the two adhesives are explained based on the type of the amines used as hardener.     

高效液相色谱与原子荧光光谱联用分析汞化合物形态的研究

建立了高效液相色谱与原子荧光光谱联用测定汞化合物形态的分析方法。实验对淋洗液组分浓度、氧化剂和还原剂浓度、载气流速及紫外消解管长度等操作条件进行了优化,获得了令人满意的分析结果。在优化的分离检测条件下,20μg/L的汞化合物标准溶液平行7次进样分析,甲基汞、无机汞和乙基汞的色谱峰高的相对标准偏差(RSD)分别为2.0%、2.9%和2.4%;3种汞化合物的线性范围为10~1000μg/L,25μL进样检出限分别为3、2和4μg/L。用建立的方法测定了脉红螺样品中甲基汞的含量,甲基汞和乙基汞的加标回收率分别为90%和92%。     

榆耳水溶性多糖的结构特征

用3%三氯醋酸从榆耳子实体中提取出水溶性粗多糖,经乙醇分级、SepharoseCL6B纯化得到单一组分GIA.SepharoseCL6B柱层析测得GIA的相对分子质量为1 26×105.GC分析表明GIA由Man和Glc两种单糖构成,其物质的量比为1 42∶1.多糖GIA经部分酸水解、高碘酸氧化、Smith降解和甲基化分析其结构主要为β(1→3)Man和β(1→3)Glc,且在6～0处构成分枝结构,平均每11个己糖残基有2个分枝,多糖GIA的支链部分由(1→4)Glc构成,末端残基为Man,Glc.     

High-resolution Hadamard transform microscope fluorescence imaging: quantifying the DNA content in single cells

This study presents a novel miniaturized Hadamard transform fluorescence imaging microscope, by combining a conventional fluorescence microscope with Hadamard transform multiplexing encoding using a one-dimensional movable mask to realize spatial resolution and a linear CCD for multichannel detection. The microscope can provide high-resolution automatically-generated 0–255 gray level HT images for morphological analysis and visualization of a single cell, and normalized HT images for cellular quantitative measurements. The microscopes imaging capability was applied to measure the DNA content in human lymphocyte, chicken erythrocyte and eel erythrocyte, and a comparative study was performed. The results show that the calibrated DNA content in a chicken erythrocyte is 2.32 pg when human lymphocyte is used as the standard, and eel erythrocyte may be a potentially reliable and novel standard for determining DNA contents in other species because it has a stable DNA value of 2.06 pg, with a CV of 4.3% when 20 eel erythrocytes are measured. The results also demonstrate that the HT imaging microscope should be valuable in the fields of medicine and cell biology.     

Acremines A-F, novel secondary metabolites produced by a strain of an endophytic Acremonium, isolated from sporangiophores of Plasmopara viticola in grapevine leaves

Six novel metabolites, acremines A-F have been isolated from agar cultures of a strain of Acremonium sp. Their structures and stereochemistry were elucidated using a combination of ¹³C and ¹H homo and heteronuclear 2D NMR experiments and X-ray analysis. Acremines A-D inhibited the germination of sporangia of Plasmopara viticola.     

有机锗(锗-132)的示差脉冲极谱研究

用示差脉冲极谱法,在pH1.30H_2SO_4和3,4-二羟基苯甲醛(DHB)底液中,获得了有机锗(Ge-132)和无机锗Ge(Ⅳ)二个配位吸附极谱波,波峰分别为E_P2-0.62V和E_pl=-0.47V(υs.AgCI/Ag),Ge-132浓度在2.6×10_(-5)～3.1×10_（-3）mol/L范围内,Ge(Ⅳ)浓度在 3.1×10_（-5）～2.1×10_（-4）mol/L范围内分别与峰电流星线性关系.利用该示差脉冲极谱法可同时测定Ge-132和Ge(Ⅳ),用于有机锗营养口服液中Ge-132和Ge(Ⅳ)的测定结果满意.还探讨了Ge-132极谱波的性质,测定了有关动力学参数.     

皮革中六价铬含量的IUC-18测定法

Ｃｒ(ＩＩＩ)是制革业最重要的鞣剂 ,制革业所用的Ｃｒ(ＩＩＩ)鞣剂由Ｃｒ(ＶＩ)还原而得到。皮革中除Ｃｒ(ＩＩＩ)外 ,还可能含有微量的Ｃｒ(ＶＩ) ,目前欧盟等国要求Ｃｒ(ＶＩ)的含量小于 5ｍｇ/ｋｇ[1 ] ;国内则还没有分析测定皮革中六价铬的国家标准 ,本文介绍六价铬的ＩＵＣ - 1 8国际标准分析方法 (ＩＵＣ ,Ｉｎｔｅｒ ｎａｔｉｏｎａｌＵｎｉｏｎｏｆＣｈｅｍｉｓｔｒｙ) ,并分析了该方法的不足及改进途径。1　实验部分ｐＨ7 5～ 8 0、惰性气体保护下用磷酸盐缓冲溶液浸取皮革的六价铬 ,六价铬将 1 ,5 二苯卡巴肼氧化为 1 ,5 二苯…     

Parameterization of OPLS-AA force field for the conformational analysis of macrocyclic polyketides

The parameters for the OPLS-AA potential energy function have been extended to include some functional groups that are present in macrocyclic polyketides. Existing OPLS-AA torsional parameters for alkanes, alcohols, ethers, hemiacetals, esters, and ketoamides were improved based on MP2/aug-cc-pVTZ and MP2/aug-cc-pVDZ calculations. Nonbonded parameters for the sp(3) carbon and oxygen atoms were refined using Monte Carlo simulations of bulk liquids. The resulting force field predicts conformer energies and torsional barriers of alkanes, alcohols, ethers, and hemiacetals with an overall RMS deviation of 0.40 kcal/mol as compared to reference data. Densities of 19 bulk liquids are predicted with an average error of 1.1%, and heats of vaporization are reproduced within 2.4% of experimental values. The force field was used to perform conformational analysis of smaller analogs of the macrocyclic polyketide drug FK506. Structures that adopted low-energy conformations similar to that of bound FK506 were identified. The results show that a linker of four ketide units constitutes the shortest effector domain that allows binding of the ketide drugs to FKBP proteins. It is proposed that the exact chemical makeup of the effector domain has little influence on the conformational preference of tetraketides.     

DTA研究二水二草酸合铬酸钾的顺、反异构化

顺—反异构体的研究,在配合物化学中占有重要的地位。二水二草酸合铬酸钾这一配合物顺、反异构体的制备和异构化现象的研究已有报导,但多限于水溶液体系。也有关于该配合物热稳定性和热分解动力学研究的报导但对固相中该配合物异构体转变的研究尚未见报导。本文利用DTA方法,对二水二草酸合铬酸钾顺、反异构体的制备以及固相中异     

Computer-aided multichannel detection in high-performance liquid chromatography

Summary The development of a computer-aided rapid-scanning detector for HPLC based on the linear photodiode array UV-visible spectrophotometer is described. Chomatograms monitored at up to three wavelengths, with automatic capture of spectra for eluted peaks and post-run processing of spectral data to generate log₁₀ (A) spectra, second derivative and fourth derivative spectra, are described. Methods are reported for the analysis of forensic samples of diacetylmorphine (heroin) in the presence of the degradation products and potential contaminants caffeine, papaverine, 6-acetylcodeine, thebaine, 6-acetyl-morphine, procaine and morphine separated by HPLC. The novel use of second and higher derivative spectra for the qualitative characterisation of drugs and contaminants separated by HPLC is described.Presented at the 14th International Symposium on Chromatography London, September, 1982