Higher order symmetrizer and application to an unusual transport equation

We study a class of stationary transport equation with nonlocal low-order tems We obtain the existence and uniqueness of a solution in sobolev spaces     

求解复杂湍流的非线性涡黏性系数模型和代数应力模型

非线性涡黏性系数模型和代数应力模型联系了线性涡黏性系数湍流模型和完整的微分 雷诺应力模型.随着它们受到日益关注,其形式也越来越多样化.本篇综述的目的是对这些模 型加以总结并比较它们之间的共同点及不同之处,指出它们与完整微分雷诺应力模型之间的 关系,以及相对于线性涡黏性系数模型而言它们在预报流场上所具有的优势.     

Development of a gas chromatographic/ion trap mass spectrometric method for the determination of levoglucosan and saccharidic compounds in atmospheric aerosols. Application to urban aerosols

We developed and validated a gas chromatographic/ion trap mass spectrometric method for the determination of levoglucosan and the related monosaccharide anhydrides, mannosan, galactosan and 1,6-anhydro-beta-D-glucofuranose in urban atmospheric aerosols collected on quartz fiber filters. The method is based on extraction with dichloromethane-methanol (80 : 20, v/v), trimethylsilylation, multiple reaction monitoring in the tandem mass spectrometric mode using the ion at m/z 217, and the use of an internal standard calibration procedure with the structurally related compound methyl beta-L-arabinopyranoside. In addition, the method allows the quantification of other saccharidic compounds, arabitol, mannitol, glucose, fructose, inositol and sucrose, which were found to be important in summer aerosols. The recovery of levoglucosan was estimated by spiking blank filters and was better than 90%. The precision evaluated by analyzing parts of the same filters was about 2% for the monosaccharide anhydrides and 7% for the other saccharidic compounds in the case of a winter aerosol sample, and the corresponding values for a summer aerosol sample were 5% and 8%. The method was applied to urban PM(10) (particulate matter of <10 microm aerodynamic diameter) aerosols collected at Ghent, Belgium, during a 2000-2001 winter and a 2001 summer episode and revealed interesting seasonal variations. While monosaccharide anhydrides were relatively more important during the winter season owing to wood burning, the other saccharidic compounds were more prevalent during the summer season, with some of them, if not all, originating from the vegetation.     

Permeability of C60 films deposited on polycarbonatesyloxane to N2, O2, CH4, and He gases

In this study, we report on the gas permeability of non-polymerized and polymerized fullerene films (thickness about 0.5 μm) grown on an organic polymer substrate, polycarbonatesyloxane (PCS), using a high vacuum deposition method. The photopolymerized C₆₀ films were prepared by a simultaneous thin film deposition and UV-vis irradiation method which was reported previously [V.A. Karachevtsev, P.V. Mateichenko, N.Y. Nedbailo, A.V. Peschanskii, A.M. Plokhotnichenko, O.M. Vovk, E.N. Zubarev, A.M. Rao, Carbon 42 (2004) 2091]. Raman spectroscopy revealed that ∼90% of the C₆₀ molecules are covalently linked to neighboring C₆₀ molecules in the photopolymerized film after 20 h of film deposition/irradiation. Permeability of the resulting membranes consisting of polymer PCS base and fullerene films to the N₂, O₂, CH₄, and He gases has been investigated. Our experiments revealed that the gas permeability properties are dependent on the age of the membrane. In particular, the aged membrane exhibited an enhanced permeability for O₂ and He gases in comparison to N₂ and CH₄, respectively.     

Determination of electron affinity of carbonyl radicals by means of negative ion mass spectrometry

Appearance energies of [M-H](-) ions from carbonyl compounds R-CO-R' (R,R' = H, CH(3), NH(2), OH) have been measured by means of negative ion mass spectrometry in resonant electron capture mode. Values of electron affinity of the corresponding radicals, CH(2)&dbond;C(X)O, NH&dbond;C(X)O and O&dbond;C(X)O, have been determined. Copyright 1999 John Wiley & Sons, Ltd.     

The multi-functional aspect of scanning holographic microscopy: a review(Invited Paper)

Recent developments in scanning holographic microscopy that offer the prospects of new quantitative tools and imaging modalities in bio, micro, and nano sciences are reviewed. The versatility of the method is emphasized. Scanning holography can operate in an incoherent mode for fluorescence imaging, in a coherent mode for quantitative phase imaging, or in a tomographic mode for axial sectioning and rejection of the out-of-focus haze. Possible applications are illustrated with examples, and future prospects ...     

Characterization of noncovalent complexes of antimalarial agents of the artemisinin-type and Fe(III)-heme by electrospray mass spectrometry and collisional activation tandem mass spectrometry

In this study, we demonstrate, using electrospray ionization mass spectrometry (ESI-MS) and collision-induced dissociation tandem mass spectrometry (ESI-MS/CID/MS), that stable noncovalent complexes can be formed between Fe(III)-heme and antimalarial agents, i.e., quinine, artemisinin, and the artemisinin derivatives, dihydroartemisinin, alpha- and beta-artemether, and beta-arteether. Differences in the binding behavior of the examined drugs with Fe(III)-heme and the stability of the drug-heme complexes are demonstrated. The results show that all tested antimalarial agents form a drug-heme complex with a 1:1 stoichiometry but that quinine also results in a second complex with the heme dimer. ESI-MS performed on mixtures of pairs of various antimalarial agents with heme indicate that quinine binds preferentially to Fe(III)-heme, while ESI-MS/CID/MS shows that the quinine-heme complex is nearly two times more stable than the complexes formed between heme and artemisinin or its derivatives. Moreover, it is found that dihydroartemisinin, the active metabolite of the artemisinin-type drugs in vivo, results in a Na(+)-containing heme-drug complex, which is as stable as the heme-quinine complex. The efficiency of drug-heme binding of artemisinin derivatives is generally lower and the decomposition under CID higher compared with quinine, but these parameters are within the same order of magnitude. These results suggest that the efficiency of antimalarial agents of the artemisinin-type to form noncovalent complexes with Fe(III)-heme is comparable with that of the traditional antimalarial agent, quinine. Our study illustrates that electrospray ionization mass spectrometry and collision-induced dissociation tandem mass spectrometry are suitable tools to probe noncovalent interactions between heme and antimalarial agents. The results obtained provide insights into the underlying molecular modes of action of the traditional antimalarial agent quinine and of the antimalarials of the artemisinin-type which are currently used to treat severe or multidrug-resistant malaria.     

Primitive Illumination Systems for Families of Convex Bodies in the Plane

Let F= {C₁,C₂,...,C} be a family of ndisjoint convex bodies in the plane. We say that a set Vof exterior light sources illuminates F, if for every boundary point of any member of Fthere is a point in Vsuch that is visible from ,i.e. the open line segment joining and is disjoint from F. An illumination system Vis called primitive if no proper subset of Villuminates F. Let p_max(F) denote the maximum number of points forming a primitive illumination system for F, and letp_max(n) denote the minimum of F) taken over all families Fconsisting of ndisjoint convex bodies in the plane. The aim of this paper is to investigate the quantities p_max(F) and p_max(n).