乙酰化淀粉/DL-丙交酯接枝共聚物的合成及降解性能研究

用醋酸乙烯酯和玉米淀粉反应制备出了不同取代度乙酰化淀粉，再用乙酰化淀粉同DL－丙交酯接枝共聚合成乙酰化淀粉／DL－丙交酯接枝共聚物。研究了原料配比，淀粉取代度对接枝反应单体转化率（C％），接枝率（G％）接枝效率（GE％）和接枝支链数均分子量（Mn)的影响，结果表明在给定的试验条件下接枝共聚反应的C％，G％，GE％和Mn可分别达到40％，225％，80％和1．4万。接枝共聚物在磷酸缓冲溶液和户外土壤掩埋降解实验表明，在160天内样品失重率分别为71％和60％，表明合成的乙酰化淀粉／DL－丙交酯接枝共聚物具有很好的降解性能。     

离子色谱法测定尿液中的C2O42-、Ca2+、Mg2+

利用离子色谱法测定尿液中的草酸根、钙、镁离子：测定草酸根时，先在尿液中加入氯化钙使之转化成草酸钙沉淀，分离后用盐酸溶解草酸钙沉淀，然后进行测定测定钙、镁离子时，在酸性尿液中加入氧化剂过硫酸钾，在微沸状态下氧化尿液中的有机物，从而避免对色谱柱的污染：草酸根、钙、镁离子的回收率分别为108．3％～109．7％、94．9％～100．7％、97．2％～97.4％，相对标准偏差分别为2．4％、2.5％、3．1％。     

高碳铬铁中磷,硅,锰的电感耦合等离子体原子发射光谱测定方法的研究

采用过氧化钠在石墨坩埚中熔融分解样品，硝酸酸化后直接用ＩＣＰ测定。磷，硅，锰的测定范围分别为０．００５％－０．０７５％，０．３０％－６．００％，０．０３％－２．００％，相对标准偏差ＲＳＤ≤６．０％。     

黄金饰品中金含量的X－荧光能谱分析

应用Ｘ－荧光能谱分析（ＥＤ－ＸＲＦ）和新的定量分析软件测定了２６个黄金标样，研究了饰品形状的影响，不同方法，不同实验室测试结果的比对，表明在所选的工作条件下样品形状无明显影响。方法可靠、快速、简便，非破坏性，适于常规、批量分析。Ａｕ含量≥９９％时，分析误差≤０．１５％，精密度≤０．１％；金含量９０％～９９％时，分析误差和精密度≤０．２％；金含量７５％～９０％和＜７５％时，分析误差分别≤０．４％和０．５％，精密度均≤０．２％；Ａｇ、Ｃｕ和Ｚｎ的分析误差均≤０．５％，精密度≤０．２％。少标样基本参数法和多标样回归法的结果一致，在实用上有重要意义，十分有利于ＥＤ－ＸＲＦ的推广应用。     

乳酸缩聚反应动力学

乳酸直接缩聚制备聚乳酸的反应在１２４℃无外加催化剂时，在反应程度１０％～６０％的范围内符合３级反应，其动力学方程式为：ｌＩ］３；在１２０℃，１％（ｗｔ）强酸性离子交换树脂作催化剂时，在反应程度１０％～５０％的范围内符合２级反应，其动力学方程式为：＝Ｉ０１ｃｏｏｎｊ＝。     

聚丙烯酰胺对粘土悬浮体的絮凝与稳定作用

研究了分子量为220万的10种水解度的PAM对高岭土的絮凝动力学曲线和对钠蒙脱土泥浆的稳定作用，发现各项性能都存在一个水解度最佳区，对高岭土的絮凝能力下在34％－41％处，钠蒙脱土悬浮体的宾汉姆屈服值τ0最大值在30％－40％处，凝胶强度τs在15％－20％处，本文从大分子形态和分散相电性质，对结果进行了讨论，指出了30％左右的水解PAM可以在钠蒙脱土和高岭土的悬浮液中，选择絮凝高岭土。     

火焰原子吸收光谱法直接测定食用菌中的铅和镉

采用火焰原子吸收法直接测定了食用菌中铅和镉的含量。方法灵敏、准确，测定时无须富集、萃取，操作简便，快速，铅和镉的相对标准偏差分别在3．3％～7．3％和3．1％～7．5％之间。回收率在94％～106％和95％～105％之间；检出限为0．016mg/L和0．008mg/L。     

环氧化植物油的制备

天然油脂在无溶剂加压（约０．１５ＭＰａ）条件下，经甲酸（８５％）、双氧水（５０％）环氧化，一步合成增塑剂兼稳定剂环氧化油脂，得微黄色油状透明液体；环氧大豆油和环氧葵子油的环氧值均在６．２％～６．６％，环氧玉米油的环氧值６．０％～６．４％；碘值小于３ｍｇ／ｇ；精油转化率１０４％～１０８％。     

微乳液增敏火焰原子吸收法测定饲料中微量镍和钴

研究了在空气-乙炔火焰中，阴离子型表面活性剂十二烷基磺酸钠（SDS）-正丁醇-正庚烷-水四组分构成的微乳液对镍钴的增敏作用。结果表明，在仪器最佳工作条件和合适酸度下，含水70％微乳液使火焰原子吸收法测镍钴的吸光度分别增敏61．1％、23．3％，使测定的灵敏度有较大的提高，用于饲料中镍钴的测定，回收率为96．4％～105．2％，相对标准偏差RSD为2.8％～5．6％，结果满意。     

核级银铟镉合金中Ag In Cd 的连续滴定

研究了测定核级银铟镉合金中Ａｇ、Ｉｎ、Ｃｄ的连续滴定法。以电位滴定法测定Ａｇ；在ｐＨ２．５以ＥＤＴＡ滴定Ｉｎ；在ｐＨ≥５．５以ＥＤＴＡ滴定Ｃｄ，当ｎ＝１１时，其ＲＳＤ分别为：Ａｇ０．１１％、Ｉｎ０．５２％、Ｃｄ１．１％，合成试样分析回收率分别为：Ａｇ９９．８％～１００．１％、Ｉｎ９９．６％～１００．３％、Ｃｏ９７．６％～１０１．３％，测定９２个合金试样，其Ａｇ，Ｉｎ，Ｃｄ合量范围为：９９．７８％～     

Alteration in photosystem II photochemistry of thylakoids isolated from senescing leaves of wheat seedlings

Wheat seedlings, grown for 7 days in the light, were allowed to senesce in the light or dark, and the change in the photosystem II (PS II) photochemistry of chloroplasts isolated from the primary leaves of these seedlings was investigated. The decrease in oxygen evolution and the fast fluorescence results indicated that the impairment of PS II in the leaves of seedlings senescing in the light was different from that in the leaves of seedlings senescing in the dark. Thermoluminescence studies showed a structural modification in the Q_B protein of chloroplasts isolated from leaves senescing in the light and an alteration in the S state transition of chloroplasts isolated from leaves senescing in the dark.     

The effect of the components of the PdCl2/Fe/I2/Py catalytic system on nitrobenzene carbonylation to ethyl N-phenylcarbamate

The PdCl₂/Fe/I₂/Py catalytic system (Py-pyridine), reported to be highly active in the reaction of nitrobenzene carbonylation to ethyl phenylcarbamate was studied. The present paper describes the role of catalyst components and its effect on the activity and selectivity of the catalyst. The increase in the amount of PdCl₂ in the system while retaining a constant level of the other catalyst components, results in the increase of both carbamate and aniline yields. The increase in the amount of iron while retaining the other components constant, initially causes an increase in the carbamate yield; however, at Fe: Pd ratios higher than 36, the carbamate yield remains constant. The change in the amount of iron has no effect on the amount of aniline formed in the system. An increase in the amount of iodine in the system while retaining the other components constant, results in a decrease in carbamate yield and a considerable increase in the aniline yield of the reaction products.     

壳聚糖及其在分析化学中的应用

综述了壳聚糖、甲壳素在污水处理、电化学、原子吸收光谱、高效液相色谱、吸光光度法中的应用。引用文献28篇。     

Radial structure and property relationship in the thermal stabilization of PAN precursor fibres

Here we report on the role of oxygen in the evolution of radial heterogeneity in the fibre structure and properties of PAN fibres stabilized in air and vacuum at different temperatures. Modulus mapping by Nano-indentation showed heterogeneous modulus distribution in the fibres treated in air, while no variation in modulus was observed in fibres processed in vacuum. Raman spectroscopy and elemental analysis revealed that the temperature dependent oxygen diffusion from skin to core of the fibres assisted in the evolution of higher extent of sp²-hybridized carbons in the skin compared to core of the air treated samples. Conversely, no radial structure variations were observed in the vacuum treated fibres. Higher modulus in the skin of air-treated fibres was due to the formation of compact structures which was associated with the enhanced intermolecular interactions facilitated by the formation of C=C bonds within the polymer backbone, promoted by oxidative-dehydrogenation reaction. Supporting these observations, the fracture morphology examined by SEM showed a brittle fracture in the skin and ductile fracture in the core.     

Sol-gel Transition of Methylcellulose Solution in the Coexistence of Hexadecyltrimethylammonium Bromide and Sodium Chloride

The sol-gel transition of methylcellulose (MC) solution in the presence of NaCl and hexade-cyltrimethylammonium bromide (HTAB), together with MC/NaCl solution in the presence of HTAB and MC/HATB solution in the presence of NaCl, was investigated by the rheolog-ical measurements. It has been found that the sol-gel transition temperature of MC solution decreases linearly with the concentration of NaCl in solution but increases linearly with the concentration of HTAB in solution, respectively. However, the sol-gel transition temperature of MC/NaCl solution in the presence of HTAB keeps the same value, independent of theconcentration of HTAB in solution. On the other hand, the sol-gel transition temperature of MC/HTAB solution decreases linearly with the concentration of NaCl in solution. The experimental results suggest that, for MC/NaCl solution in the presence of HTAB, the salt-induced spherical micelles of HTAB should have formed in bulk solution. For MC solution in the absence of NaCl, no spherical micelles have been formed in bulk solution, though the concentration of HTAB in our experiment is almost one order of magnitude higher than the critical micelle concentration of HTAB in polymer-free solution. In fact, due to adsorption of HTAB on MC chains, the realconcentration of HTAB in bulk solution, is much less than the apparent concentration of HTAB dissolved in MC solution.     

Analytical strategies to determine antibiotic residues in fish

The accelerated growth of aquaculture has resulted in a series of harmful effects to human health. The widespread and unrestricted use of antibiotics in this industry, to prevent bacterial infections, leads to remaining amounts in the aquatic environment. This has resulted in the emergence of antibiotic-resistant bacteria in aquaculture environments, in the increase in antibiotic resistance in fish pathogens as well as in the transfer of these resistance determinants to human pathogens. Moreover, the use of large amounts of antibiotics may lead to the presence of residual antibiotics in fish tissue and fish products. Fluoroquinolones, tetracyclines, penicillins, sulphonamides and other antibiotics, exhibiting activity against both Gram-positive and Gram-negative bacteria, are widely used for the treatment and prevention of diseases in fish. An extended and comprehensive review on the recent analytical methodologies concerning antibiotic residues in fish reported in the literature is provided in the present article. Emphasis is given on sample preparation regarding isolation and purification, chromatographic conditions and method validation according to legislation. Results of published assays are comparatively presented and criticised.     

ESR方法检测竹红菌素的半醌负离子自由基

从顺磁共振波谱检测到通过竹红菌素的光诱导还原和基态竹红菌素跟脂肪胺的电子转移两条途径所得到的自由基信号, 并由电化学还原得到同一自由基, 确认它为半醌负离子自由基。竹红菌素溶液中加入芳香胺观察不到ESR信号。它的3,10位上与醌基相邻近的羟基离解以后, 无论在基态还是在激发态都观察不到ESR信号。此外, 还从吸收光谱观察到半醌负离子自由基吸收以及竹红菌素跟脂肪胺之间的相互作用。     

Changes in density and surface tension of water in silica pores

 The density and surface tension of water in small pores of silicas have been investigated. These physical properties of water in the pores were calculated from a comparison of pore volumes and pore radii which were estimated from adsorption and desorption isotherms of nitrogen and water. Below a pore radius of about 5 nm both the density and the surface tension of water in the pores were smaller than those of the bulk liquid and decreased with a decrease in pore size. The density of water in the pores decreased with an increase in the concentration of surface hydroxyl groups. Similarly the surface tension of water in the pores is influenced by the surface hydroxyl groups. Anomalous changes in the density and surface tension of the water in the pores are attributed to the interaction of water molecules with surface hydroxyl groups and hydrogen-bond formation among water molecules. Received: 20 April 1999 Accepted in revised form: 17 November 1999     

Photoelectric effects on chlorophyll fluorescence of photosystem II in vivo. Kinetics in the absence and presence of valinomycin

Fluorescence induction curves (F(t)) in low intensity 1s light pulses have been measured in leaf discs in the presence and absence of valinomycin (VMC). Addition of VMC causes: (i) no effect on the initial fluorescence level Fo and the initial (O-J) phase of F(t) in the 0.01-1 ms time range. (ii) An approximately 10% decrease in the maximal fluorescence Fm in the light reached at the P level in the O-J-I-P induction curve. (iii) Nearly twofold increase in the rate and extent of the F(t) rise in the J-I phase in the 1-50 ms time range. (iv) A 60-70% decrease in the rise (I-P phase) in the 50-1000 ms time range with no appreciable effect, if at all, on the rate. System analysis of F(t) in terms of rate constants of electron transfer at donor and acceptor sides have been done using the Three State Trapping Model (TSTM). This reveals that VMC causes: (i) no, or very little effect on rate constants of e-transfer reactions powered by PSII. (ii) A manifold lower rate constant of radical pair recombination (k(-1)) in the light as compared to that in the control. The low rate constant of radical pair recombination in the reaction center (RC) in the presence of VMC is reflected by a substantial increase in the nonzero trapping efficiency in RCs in which the primary quinone acceptor (Q(A)) is reduced (semi-open centers). This causes an increase in their rate of closure and in the overall trapping efficiency. Data suggest evidence that membrane chaotropic agents like VMC abolish the stimulation of the rate constant of radical pair recombination by light. This light stimulation that becomes apparent as an increase in Fo has been documented before [Biophys. J. 79 (2000) 26]. It has been ascribed to effects of (changes in) local electric fields in the vicinity of the RC. The decrease of the I-P phase is attributed to a decrease in the photoelectric trans-thylakoid potential in the presence of VMC. Such effects have been hypothesized and illustrated.     

Effect of plasticizer concentration on the hysteresis,tear strength and stress-relaxation characteristics of black-loaded rubber vulcanizate

The effect of plasticizer concentration on the stress softening, tear strength and stress relaxation of black loaded bromobutyl rubber vulcanizate has been investigated. The stress softening in the rubber vulcanizate, an energy dissipative process at higher strain, may be explained primarily by changes that take place in the rubber phase of the filled vulcanizate. Increased plasticizer concentration leads to decrease in the equilibrium hysteresis. A quantitative relationship between energy density and hysteresis has been derived, which is applicable at and below the elongation at break. Increase in plasticizer concentration results in decrease in the effective diameter of the tip of the tear, which in turn decreases the tear strength. Rate of relaxation decreases with increase in the plasticizer concentration in the carbon-black-filled vulcanizate.