Microwave-assisted three-component Knoevenagel-nucleophilic aromatic substitution reactions

A powerful microwave-assisted three-component Knoevenagel-nucleophilic aromatic substitution reaction of 4-halobenzaldehydes, cyanoacetatic acid esters/cyanoacetamides, and cyclic secondary amines has been developed.     

GC Analysis of the Fatty Acid Composition of Yak Kidney

To obtain valuable information for development of potential commercial products from yak kidney, which is usually treated as waste, the fatty acid composition of kidneys from yak reared in Gansu province, China, was investigated by gas chromatography. Fifteen different fatty acids were identified. The major fatty acids are oleic acid (33.3%), stearic acid (20.2%), and palmitic acid (18.4%). More interestingly, several important and essential fatty acids were also identified, including conjugated linoleic acid (2.94%), omega-3 fatty acids, for example docosahexaenoic acid (1.47%), eicosapentaenoic acid (1.11%) and alpha linolenic acid (0.37%), and omega-6 fatty acids, for example arachidonic acid (2.86%) and linoleic acid (1.98%). The results show that the fatty acid composition of yak kidney is of reasonable value and is suitable for further development of possible commercial products. This is the first report of the fatty acid profile of yak kidney.

     

Quasi‐random graphs with given degree sequences

It is now known that many properties of the objects in certain combinatorial structures are equivalent, in the sense that any object possessing any of the properties must of necessity possess them all. These properties, termed quasirandom, have been described for a variety of structures such as graphs, hypergraphs, tournaments, Boolean functions, and subsets of Z _n, and most recently, sparse graphs. In this article, we extend these ideas to the more complex case of graphs which have a given degree sequence. © 2007 Wiley Periodicals, Inc. Random Struct. Alg., 2008     

Analysis of Electromagnetic Scattering from Plasma Antenna Using CG-FFT Method

A gaseous plasma column as an efficient radiator of electromagnetic waves is well known. This paper presents the scattering analysis of a plasma antenna using the conjugate gradient fast Fourier transform (CG-FFT) method. Radar cross sections (RCS) of designed plasma antenna for different plasma parameters are computed mainly. Numerical results show that the plasma antenna with appropriate parameters can offer lower RCS than the metal one. It is evident from the observed scattering characteristics that the plasma antenna can be regarded as a rod of imperfect conductor with losses.     

Determination of inorganic anions in ethyl acetate by in-line hollow fiber membrane extraction with ion chromatography

In this work,a novel hollow fiber membrane extractor was set up to extract inorganic anions from ethyl acetate using deionized water.Inorganic anions in slightly soluble organic solvents can be determined by the in-line hollow fiber membrane extractor coupled with ion chromatography at first time.Different aspects of the extraction procedure such as magnetic stirring speed, extraction flow rate and extraction time were optimized to achieve high extraction efficiency and good separation results. Satisfact...     

Evaluation of separation quality in two-dimensional hyphenated chromatography

In this paper, a novel criterion named the overlap index (OVI) has been proposed to evaluate the separation quality in two-dimensional hyphenated chromatography. This criterion, which is obtained from the maximum value of the Gram determinant constructed by the key spectra, can reveal the degree of two-dimensional hyphenated chromatographic separation. The key spectra are selected based on the so-called D-optimal criterion. According to its geometrical sense meaning the volume spanned by the constructed vectors, OVI criterion can practically reflect the overlap degree of chromatographic peaks. The OVI criterion is further interpreted by comparing the resolution of two-dimensional data into pure chromatograms and spectra. The successful application of this OVI criterion to both of simulated two-dimensional hyphenated data and the real case in analyzing the six reference phenolic compounds from Ginkgo biloba L-leaves shows its reliability and practicality.     

CE determination of quinolones in the presence of bovine serum albumin

This article describes the influence of bovine serum albumin (BSA) as an additive on the capillary electrophoresis–potential gradient determination of five quinolones, enoxacin, norfloxacin, ofloxacin, fleroxacin, and pazufloxacin. With 10 mg/L of BSA present in the buffer of 30 mM Tris and 3 mM phosphoric acid at pH 9, the detection limits of the five quinolones were in the range of 0.24–0.68 mg/L, i. e. 5.8–16.5‐fold lower than those obtained with the buffer devoid of BSA, and the analysis time was shortened. We suggest that the inner wall‐adsorbed BSA suppresses the adsorption of quinolones and simultaneously enhances the electroosmotic flow rate. Our experiments indicated that adopting the potential gradient detection technique could eliminate the interference of the UV‐active proteins on the detection of quinolones that would occur with conventional optical detection, and therefore offer high detection sensitivity. As a demonstration, the method was applied to the determination of QNs in fortified chicken muscle sample with satisfactory results.