天然药物及制剂中微量元素硒的测定方法概况

硒是人体必需的微量元素，具有抗肿瘤、防衰老、防辐射和增强机体免疫力等多种功能。本文就国内近年来对天然药物及其制剂中微量元素硒的分析方法概况作一综述，包括：原子吸收分光光度法、荧光分光光度法、电感耦合等离了光谱法、催化分光光度法、分光光度法、化学发光淬灭法、极谱法、中子活化分析法和色谱法等。     

Effect of pressure on oxygen enrichment of liquid crystalline cellulose ether membranes at elevated temperature

Cholesteric liquid crystalline triheptyl cellulose (THC)/ethyl cellulose binary blend membranes were prepared and the effect of pressure on their oxygen enrichment at elevated temperature was investigated using a constant pressure-variable volume method. The oxygen enrichment increased with the increase of transmembrane pressure difference or with slight increase of the THC content in the blend membranes. The oxygen concentration through the membranes increased linearly with decreasing pressure ratio. Air was directly separated through a 17 m-thick THC/EC(1.5/98.5) membrane to prepare an oxygen-enriched air containing 39.5% oxygen at the flux of 6.99×10^–4 cm³ (STP)/s.cm² at the pressure difference of 0.43 MPa and 85 °C.     

聚合物硼氢阴离子还原剂的制备及其对酯的还原研究

氯型季我安盐型强碱性阴离子交换树脂７１１＾＃与硼氢化钾反应制得聚合物硼氢阴离子还原剂，树脂容量３．２ｍｍｏｌ ＢＨ４／ｇ。用于不同酯化合物的还原，操作简便，树脂可再生重复使用。     

Studies on Cyclodextrin Inclusion Complex by Fluorescence Anisotropy

An equation for determining the equilibrium association constant (KA) of cyclodextrin inclusion complex with fluorescence anisotropy is derived and used to determine KA of pyrene-B-cyclodextrin inclusion complex. The existing forms of cyclodextrin inclusion complex in solution, the interaction type of host with guest, and the possibility of application of B-cyclodextrin in the analysis of metal ions using naphthalene derivative as a ligand are discussed based on the equation derived along with the curve of fluorescence anisotropy versus cyclodextrin concentration of guest/cyclodextrin system.     

用原子捕获技术提高火焰原子吸收光谱法的灵敏度

采用简易的石英原子捕获器，使Ｃｕ，Ａｇ，Ａｕ，Ｚｎ，Ｃｄ，Ｐｂ，Ｓｂ，Ｂｉ等易挥发元素在空气－乙炔火焰原子吸收光谱法中的灵敏度提高了３～５倍，并有较好的精密度，相对标准偏差在１％左右，方法中用此技术测定了标准物质中Ｐｂ、Ｃｄ的含量，获得了满意的结果，它较之石墨炉原子吸收光地具有快速，简便的特点，具有较大的实用价值。     

Isothermal Titration Microcalorimetric Studies of the Effect of Temperature on Hydrophobic Interaction between Proteins and Hydrophobic Adsorbents

This study attempted to comprehend how temperature affects hydrophobic interaction between proteins and hydrophobic adsorbents. By equilibrium batch analysis, we measured the adsorption isotherm to evaluate the protein-adsorbent affinity, while isothermal titration calorimetry was used to measure the adsorption enthalpy. In addition, the affinity and enthalpy differences between two proteins, alpha-chymotrypsinogen A and trypsinogen, with two adsorbents, butyl-Sepharose and octyl-Sepharose gel, under varying temperatures were studied with respect to the exposed hydrophobic segments of the protein and ligand hydrophobicity. The enthalpies obtained in this investigation can be used to more thoroughly understand the hydrophobic interaction between proteins and adsorbents. First, the adsorption isotherm experiments reveal that the adsorption quantity of the proteins with the Sepharose gels increases with temperature. For a microcalorimetric measurement, as temperature is increased from 298 to 310 K, the DeltaH value of alpha-chymotrypsinogen A with butyl-Sepharose increases, while the DeltaH value of trypsinogen is reduced. This is likely due to the fact that alpha-chymotrypsinogen A has a higher area of exposed hydrophobic segments than trypsinogen does. This observation also implies that as temperature increases, the interaction mechanism of alpha-chymotrypsinogen A with butyl-Sepharose changes from an adsorption-dominated process to a partitioning process. In addition, for octyl-Sepharose, the DeltaH value of alpha-chymotrypsinogen A is positive and decreases with temperature increment. However, the DeltaH value of trypsinogen was positive and increased with temperature. Therefore, we conclude that as temperature increases, the interaction mechanism of the proteins for octyl-Sepharose is a partitioning-dominated process. Copyright 2000 Academic Press.     

Spontaneous Vesicle Formation in Aqueous Mixtures of Cationic Surfactants and Partially Hydrolyzed Polyacrylamide

Spontaneous vesicle formation was observed in aqueous mixtures of partially hydrolyzed polyacrylamide and single-tailed cationic surfactants. The influences of pH, addition of long-chain alcohols, variation of hydrocarbon chain length, and head group size of the cationic surfactants were investigated systematically. It was found that 30-50% hydrolyzed degree of polyacrylamide and cationic surfactants with 10 or 12 methylene groups are suitable for vesicle formation in the mixed aqueous systems at pH 9.2. Addition of long-chain alcohols was found to be helpful for vesicle formation in some cases. The vesicle stability was also investigated at various temperatures and amounts of ethanol addition. Copyright 2001 Academic Press.     

Synthesis,spectroscopy and thermal properties of the nickel(II), palladium(II) and copper(II) complexes of bis(aminoalkyl)-oxamides (=LH2) including the crystal structure of Cu2L(NO3)2

Summary The synthesis of the Ni^II, Pd^II and Cu^II complexes of N, N-bis(aminoalkyl)oxamides (LH₂) is described and structures are proposed on the basis of their physical and spectroscopic properties. With Ni^II and Pd^II only one complex is formed with general formula NiL or PdL, characterised by coordination through two deprotonated amide N-atoms and two terminal NH₂ groups. With Cu^II it proved possible to obtain three structurally different compounds, depending on the pH, with general formulae Cu(LH₂)X₂, Cu₂(L)X₂ and CuL in which X=Cl, Br or NO₃. The structure of [Cu₂(C₈O₂N₄H₁₆](NO₃)₂ was solved by means ofx-ray diffraction; Mr=451.33, monoclinic, space group P2₁/n, a=9.503(4), b=7.614(1), c=10.407(3) Å, =98.43(3)°, V=744.3(7)ų, Z=2, Dx=1.202 g cm^–3, =1.33 cm^–1, (MoK)=0.71073 Å, F(000)=520, room temperature, R=0.043, wR=0.047 for 1080 observed [I>-3(I)] not systematically absent reflections out of 1423 measurements and 137 variables. The compound has a conformational chair/boat disorder with 82% in the more stable chair form.     

delta-Aminolaevulinic acid mediated photodynamic antimicrobial chemotherapy on Pseudomonas aeruginosa planktonic and biofilm cultures

To demonstrate photodynamic antimicrobial chemotherapy (PACT) against planktonic and biofilm cultures of Pseudomonas aeruginosa, using photoporphyrin IX which could be endogenously synthesized by administrating delta-aminolaevulinic acid (delta-ALA), and a light emitted diode (LED) array to photoactivate the photosensitizer. P. aeruginosa suspended cells or biofilms, grown on a rotating disk reactor, were treated by different concentrations of delta-ALA in the dark for 1 h, followed by LED irradiation for various time. Regrowth experiments were conducted by placed PACT-treated disks back to a sterile reactor. Viable cells were determined by serial dilution and plate counts. Both P. aeruginosa planktonic and biofilm cells were inhibited by PACT with light doses or photosensitizer concentrations increasing. Treatments of planktonic cells with 10 mM delta-ALA and incident dose 240 J cm(-2) or 7.5 mM ALA and incident dose 360 J cm(-2) led to completely photoinactivation. No viable biofilm cells were found after treatment of 20 mM delta-ALA and incident dose 240 J cm(-2). However, regrowth was observed once PACT-treated biofilms were put back to a sterile reactor. Regrowth could be prevented only if biofilm samples were treated PACT twice. delta-ALA-mediated PACT on P. aeruginosa planktonic and biofilm cells was effective, though the detailed mechanism still required further investigation.     

Diffraction techniques for nonlamellar phases of phospholipids

A neutron diffraction method applicable to nonlamellar phases of substrate-supported lipid membranes is described and validated. When prepared on a flat substrate, the resulting nonlamellar phases have layered symmetry which provides some advantages over powder diffraction for detailed structure determination. This approach recently led to the detection of a rhombohedral phase and a distorted hexagonal phase of lipids. Here the determination of intensity and phase information for such phases is demonstrated by application to the hexagonal phase of diphytanoyl phosphatidylcholine (DPhPC). The hexagonal symmetry is used to verify the data reduction procedure for the intensities of the diffraction peaks. Diffraction intensities measured while varying the D2O/H2O ratio in the relative humidity was used to solve the phase problem. The neutron scattering length density distribution of the hexagonal phase was constructed and analyzed to elucidate the packing of the lipid molecules. The structure of DPhPC in the hexagonal phase is of interest in connection with its stalk structure in the rhombohedral phase. We also found that the incorporation of tetradecane into the DPhPC hexagonal phase is limited, similar to the case for dioleoyl phosphatidylethanolamine.