Simultaneous quantification of leukotrienes and hydroxyeicosatetraenoic acids in cell culture medium using liquid chromatography/tandem mass spectrometry

Leukotrienes (LTs) and hydroxyeicosatetraenoic acids (HETEs) are important bioactive lipid mediators that participate in various pathophysiological processes. To advance understanding of the mechanisms that regulate these mediators in physiological and pathological processes, an analytical method using liquid chromatography/tandem mass spectrometry for the simultaneous quantification of LTB₄, LTC₄, LTD₄, LTE₄, 5‐HETE_, 8‐HETE, 12‐HETE and 15‐HETE in cell culture media was developed. A Supel?‐Select HLB solid‐phase extraction cartridge was used for sample preparation. The compounds were separated on a C₁₈ column using gradient elution with acetonitrile–water–formic acid (20:80:0.1, v/v/v) and acetonitrile–formic acid (100:0.1, v/v). The calibration curves of LTB₄, LTD₄, LTE₄ and HETEs were linear in the range of 0.025–10 ng/mL, and the calibration curve of LTC₄ was linear in the range of 0.25–10 ng/mL. Validation assessment showed that the method was highly reliable with good accuracy and precision. The stability of LTs and HETEs was also investigated. Using the developed method, we measured LTs and HETEs in the culture supernatant of the human mast cell line HMC‐1. The present method could facilitate investigations of the mechanisms that regulate the production, release and signaling of LTs and HETEs. Copyright © 2014 John Wiley & Sons, Ltd.     

一种可能的简并谱NNS分布

利用随机矩阵理论,通过对一特殊情形的简并谱展开研究,得到了简并谱一种可能的最小相邻间距NNS分布函数．研究表明,由于简并的存在,简并谱不仅可分解成随机谱和规则谱两个子谱,同时还影响其规则谱,使规则谱的能级斥力减少．     

System Identification Models of the Equivalent Permittivity for Rain Medium

The dielectric constant for rain medium is investigated by utilizing the system identification method. The rain rate model and frequency model of permittivity in millimeter waves band for rain medium are presented. The results obtained with models are in very good agreement with references in calculating the attenuation of electromagnetic waves induced by rain, which Shows that the obtained models are valid and practicable. The cross-polar discrimination gotten with rain rate model is in agreement with references.     

Synthesis of molecular imprinted organic-inorganic hybrid polymer binding caffeine

Random copolymers of poly{(methacrylamide)-co-(vinyl trimethoxysilane)} and poly{(methacrylic acid)-co-(vinyl trimethoxysilane)} were synthesized via a free radical polymerization reaction. Acid catalyzed sol-gel process of tetraethylorthosilicate (TEOS) with aforementioned polymers in the presence of methyl xanthine class of alkaloid like caffeine resulted in the formation of highly transparent monoliths. Solvent extraction of the template leaves behind the recognition sites intact with high selectivity towards the print molecule. The ionic and non-specific adsorptions, which are considered to be the main disadvantages of the molecularly imprinted polymers (MIP), are prevented to a considerable extent by the end capping of surface silanol groups. The template binding efficiencies of MIP were determined by HPLC analysis.     

Preparation and characterization of acrylic‐based black particles of poly(methyl methacrylate‐co‐ethylene glycol dimethacrylate) by dispersion polymerization for electrophoretic displays

Ultrafine black particles, ranging in diameter from 1 to 3 μm, were prepared by dispersion polymerization in a methanol/water mixture with vinyl monomers, nonpolymerizable Sudan black B dyes, and fluorescein isothiocyanate labeled charge control additives. Both the ratio of the methanol to the water dispersion medium and the polymeric stabilizer concentration had significant effects on the particle size. The important role of the stabilizer concentration lay in the particle formation step, during which it determined the particle stability and final particle size. These could affect the extent of the aggregation of nuclei by changing the adsorption rate of the stabilizer and the viscosity of the dispersion medium, resulting in smaller particles. The fluorescent‐labeled charge control additives strongly affected the electrophoretic mobility. A small concentration of fluorescent‐labeled charge control additives increased the electrophoretic mobility. However, a further addition reduced the electrophoretic mobility of the polymer particles. The concentration dependence of the fluorescent‐labeled charge control additives on the deposition behavior in the polymer particles was successfully imaged and thereafter quantified by image analysis. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5608–5616, 2004     

Diffusion in poro‐plastic media

A model is developed for the flow of a slightly compressible fluid through a saturated inelastic porous medium. The initial‐boundary‐value problem is a system that consists of the diffusion equation for the fluid coupled to the momentum equation for the porous solid together with a constitutive law which includes a possibly hysteretic relation of elasto‐visco‐plastic type. The variational form of this problem in Hilbert space is a non‐linear evolution equation for which the existence and uniqueness of a global strong solution is proved by means of monotonicity methods. Various degenerate situations are permitted, such as incompressible fluid, negligible porosity, or a quasi‐static momentum equation. The essential sufficient conditions for the well‐posedness of the system consist of an ellipticity condition on the term for diffusion of fluid and either a viscous or a hardening assumption in the constitutive relation for the porous solid. Copyright © 2004 John Wiley & Sons, Ltd.     

Refraction of light in media

The roles of the magnetic field and electric field of the light are investigated when the light is refracted in the medium. The model of the electron cloud conductor is presented. Electron cloud in a molecule is treated as a conductor and the Faraday’s Law is applied to this conductor that is in the alternating magnetic field of the light. dB _M/dt of the light gives rise to an alternating induced current on the electron cloud conductor, and the light exchanges energy, i.e. the refractive energy, with the electron cloud conductor. Formulas of refractive index, which is the ratio of light speed in vacuum to that in the medium, are derived with this model. These formulas are tested with several mediums and Langevin’s diamagnetic susceptibility of helium gas, and the results are in good agreement with the measured data. The anisotropy and the nonlinearity of the refractive index are explained with the theory described in this work. Supported by Beijing Science and Technology New Star Program (Grant No. 952870400), the Beijing Municipal Commission of Education and the Excellent Young Teachers Program of Ministry of Education of China     

THE DIMENSION FOR RANDOM SUB-SELF-SIMILAR SET

In this article,the Hausdorff dimension and exact Hausdorff measure function of any random sub-self-similar set are obtained under some reasonable conditions.Several examples are given at the end.