气相色谱质谱法快速测定人血浆中克仑特罗

血浆样品经0.01mol·L-1盐酸和无水乙醇浸取,在碱性条件下用氯仿萃取,GG-MS-选择离子测量法测定,外标法定量。在选定的色谱条件下,盐酸克仑特罗的检出限为0.05ng,线性范围为0.1-100ng,方法的平均回收率为95.6％,RSD小于6.82％(n=6)。该法毋需衍生化,基质无干扰,简便可靠,适用于生物材料中克仑特罗的快速分析。     

Synthetic receptors based on calix[4]arene functionalized at the lower rim in molecular recognition of dicarboxylic, α-hydroxycarboxylic,and α-amino acids

New calix[4]arenes, di- and tetrasubstituted at the lower rim, with different functional groups were synthesized. They were studied as carriers of a series of dicarboxylic and -hydroxycarboxylic acids through a liquid impregnated membrane. The calix[4]arenes under study are capable of molecular recognition of oxalic acid in the series of structurally similar dicarboxylic and -hydroxycarboxylic acids. The regularities found make it possible to change purposefully the receptor ability of 1,3-disubstituted calix[4]arenes by variation of the nature of substituents.     

A High Sensitivity Fluorescent Chemo-sensory System Based on β-Cyclodextrin Dimer Modified with Dansyl Moieties

-Cyclodextrin dimer linked with ethylenediamine at the upper rim of the cyclodextrin has been synthesized and then modified with two dansyl moieties inthe presence of N,N'-dicyclohexylcarbodiimide. The sensing ability and bindingproperty of the title compound were investigated for steroids and terpenoids. Thefluorescence intensity of this dimer was decreased when a host–guest complex was formed. The value I/I⁰, where I⁰ and I are fluorescence intensitiesin the absence and presence of a guest and I is I⁰- I, was used as a parameter of sensitivity. This host exhibited a much higher sensitivity and selective molecular recognition ability for bile acids such as ursodeoxycholic acid andchenodeoxycholic acid and terpenoids such as (-)-borneol than the dansyl-modifiedcyclodextrins reported previously including -cyclodextrin dimer. The behaviors of the appended moieties of the host during the formation of host–guest complexes were studied using induced circular dichroism (ICD) and fluorescence spectra. The ICD intensityof this dimer was decreased on accommodation of a guest and this spectral pattern of the title dimer was opposite to that of bis dansyl-modified -cyclodextrin monomer. Theguest-induced variations in the fluorescence and ICD intensities suggest that this dimer formed a 1 : 1 host–guest complex and the appended moieties act as a hydrophobic cap.     

Can the new ISO Guide 25/EN 45001 create better confidence in laboratory operations?

 Confidence in laboratory operations is discussed based on the ongoing revision of the ISO/IEC Guide 25. Confidence is a subjective attribute, which also depends on whose interest is considered. New and better-defined quality systems and technical elements will be included, and these are beneficial to the transparency of laboratory operations, as well as to the accreditation process. The ultimate aim is, of course, to satisfy customers. The testing laboratories' industrial customers are, however, generally unfamiliar with the ISO/IEC Guide 25 and accreditation. The main reason for improved confidence in testing and calibration laboratories is foreseen to come from closer interaction between laboratories and their customers.     

Applicability of polymer theories to the thermodynamics of proteins at the air/water interface: example of β-lactoglobulin

Knowledge of the equation of state of adsorbed or deposited layers of proteins at the air/water interface is of fundamental interest in the understanding of the surface activity of these molecules. Using scaling laws of current polymer theories, it has been shown that the equation of state of the interfacial layer in the semi-dilute regime should relate the surface pressure to the surface concentration through a power law. The exponent of this power law should reflect the quality of the solvent and the conformation of the adsorbed polypeptide chain. In the case of β-lactoglobulin layers, in the range of surface concentrations that should correspond to the semi-dilute regime, the relationship between surface pressure and surface concentration is expressed as a power law. The exponent of this power law is strongly influenced by the nature of the aqueous substrate and by the net charge of the protein molecule. The use of scaling laws gives a coherent view of the expansion of the polypeptide chain in the interfacial layer and of the relationship between surface concentration and surface pressure in the semi-dilute regime. This result favours a strong similarity between β-lactoglobulin and a polymer chain in the interfacial layer. It is concluded that current theories of polymer adsorption could be applied to interfacial protein layers.     

STRUCTRE AND PROPERTIES OF COMPOSITE Ni/HARD CARBON FILMS PREPARED BY PLASMA DEPOSITION

IntroductionHardcarbonfilmsprcparcdb}'vari0usplasmaprocesscsareofc0nsidcrablcinterestbccauscofthcirunusualmcchanical-opticalandelcctricalpropertiesll~3l.Rccently,ithasReceive(IJl111c5,l9`)5;,.`,1iis()tI1ie)\tioII,1'ceil'edJtl1)'l4,l995*'I11isprojectiss[1pportcdh}tl1cNatiol1a1Nat[lntlScicl1ccI`()ul1dati()l1ofCl1il1aal1dtl1eI,aboraton'ofSolidI,ubricati()l1,l.al1/l10ulnstitutcofCl1cn1icalPh\'sics,111cChincscAcadcl11\'ofScicnccs.benfoundthattheinc0rporati0nofmetaIintocarbonfilmscangrcatl}'…     

The importance of nonconventional structures in the binding of Ni<Superscript>+</Superscript> to ethynylsilanes and ethynylgermanes

The influence of the nature of the heteroatom on the Ni⁺ gas-phase binding energies of HCC–XH₃ (X is C, Si, or Ge) compounds has been investigated through the use of high-level density functional theory methods. The structures of the corresponding Ni⁺ complexes were optimized at the B3LYP/6-311G(d,p) level of theory. Final energies were obtained in single-point B3LYP/6-311+G(2df,2p) calculations. Nonconventional complexes, in which the metal cation interacts simultaneously with the CC system and with one of the X–H bonds of the substituent XH₃ group, play a significant role in the binding of Ni⁺ to HCC–XH₃ (X is Si or Ge) derivatives. Conversely, such nonconventional complexes are not local minima of the propyne–Ni⁺ potential-energy surface. This establishes a clear distinction between unsaturated carbon derivatives and the Si- and Ge-containing analogues as far as bonding to transition-metal monocations is concerned. Actually, the attachment of Ni⁺ to HCC–XH₃ (X is Si or Ge) compounds in the gas phase yields a mixture of conventional and nonconventional complexes. These agostic-type interactions can be viewed as a dative bond from the X–H bonding orbital toward the empty s orbital of the metal, and a back-donation from the valence electron pairs of the metal into the X–H antibonding orbital of the neutral species.Proceedings of the 11th International Congress of Quantum Chemistry satellite meeting in honor of Jean-Louis Rivail     

手性环丙烷类衍生物双水解转换的研究

具有四个新手性中心的螺环／环丙烷类化合物4在丙酮－12％HCl溶液中50℃下 发生双手性辅基－双水解转换反应，得到了手性环丙烷／双半缩醛类化合物，螺 [1-溴－4－羟基－5－氧杂－6－氧代双环[3.1.0]己烷－2，2′-(3′-亲核氧基－ 4′－羟基丁内酯）]（5），化学产率65％－79％，光学纯度ee≥98。通过元素分 析，[a]D^20,UV,IR,^1H NMR,^13C NMR,MS以及X射线四圆衍射测定，确认了它们的 化学结构、立体化学和绝对构型。该双半缩醛类化合物的合成方法学研究可为官能 团的转换，为某些复杂结构的手性化合物提供新的合成方法和途径。     

The decomposition of edta-gel precursors in the production of BSCCO superconductors

The decomposition of EDTA gel precursors for BSCCO superconductor manufacture has been studied using STA (TG/DTA) and dilatometry in conjunction with FTIR. The thermoanalytical data are discussed in relation to the sequence of phase formation necessary for the production of the 2223 BSCCO superconducting phase. The effects of substitution of Pb for Bi on the temperatures of formation of the superconducting phases is also discussed. STA has also been carried out under varying oxygen partial pressures to determine the effects of oxygen pressure on the formation and decomposition of the phases involved in the production of the 2223 compound.     

The interaction of double-charged metal ions with monolayers and bilayers of phospholipids

Electrophoretic mobilities of hexadecane/water emulsions containing dimyristoyl-phosphatidylcholine (DMPC) or egg yolk lecithin (EYL) monolayers at the interface and those of liposomes prepared from the same lipids were measured as functions of the concentrations of Ca²⁺, Mn²⁺, Cu²⁺, and Ni²⁺ cations in the aqueous phase. The surface potentials, surface charge densities (σ), and the Langmuir adsorption isotherms for various distances from the charged surface to the slip plane (d) were calculated on the basis of the Gouy-Chapman theory for 1∶2 electrolytes and the values of ζ-potentials. The binding constants (K) and parametersd were determined under the assumption that the maximum σ values correspond to one ion per phospholipid molecule at the interface. In the case of DMPC, the ion binding constants (L mol⁻¹) at 25°C are 230 and 87 for Ca²⁺, 31.5 and 21 for Mn²⁺, 11 and 6 for Cu²⁺, and 7.5 and 5.3 for Ni²⁺ in liposomes and emulsions, respectively. The affinities of Cu²⁺ and Ni²⁺ ions for EYL monolayers and bilayers are lower than those for DMPC mono- and bilayers. Thed parameters for all ions are smaller than the radii of the hydrated ions. In the case of Ca²⁺, Cu²⁺, and Ni²⁺, thed values for mono- and bilayers are different. The differences in K values between monolayers and bilayers as well as those between DMPC and EYL mono- and bilayers can be attributed to the differences in the local environment and orientation of the interfacial phosphate groups in these systems. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2490–2495, December, 1998.