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61.
A high-performance liquid chromatographic method was developed for the determination of five penicillins: penicillin G (PENG), penicillin V (PENV), oxacillin (OX), cloxacillin (CLO), and dicloxacillin (DICLO), in bovine muscle. Samples were macerated with a mixture of H(2)O/CH(3)CN (1:1) and purified using RP-8 Adsorbex SPE cartridges after centrifugation, with mean recovery from spiked samples higher than 89%. The separation of the examined penicillins was achieved on an analytical column, an Inertsil C8 5 microm, 250x4 mm(2), at ambient temperature. The mobile phase consisted of 0.1% TFA/ACN 50:50 v/v delivered isocratically at a flow rate of 1.1 mL/min. Analytes were monitored at 240 nm. The procedure was validated according to the European Union Decision 2002/657/EC by means of selectivity, stability, decision limit, detection capability, accuracy, and precision. Method's LOQ values achieved were 54 microg/kg for PENG and DICLO, 46 microg/kg for PENV, 16 microg/kg for OX, and 43 microg/kg for DICLO. The detection capabilities (CC(beta)) were 73.6 microg/kg for PENG, 29.1 microg/kg for PENV, 350.6 microg/kg for OX, 379.9 microg/kg for CLO, and 355.8 microg/kg for DICLO. The method was applied to various samples from the local market. Two penicillins were identified by photodiode array (PDA) detection and quantified. 相似文献
62.
63.
Ioannis Papadoperakis 《Geometriae Dedicata》1999,75(3):275-285
Let A be a convex body in Euclidean space E3. We denote by H(A) the smallest number of homothetic 'reduced copies of A by which it is possible to cover the whole of A. The conjecture of Hadwiger is H(A) 8. We prove that H(A) 16. 相似文献
64.
Trans-hydrogen-bond deuterium isotope effects of Watson-Crick A:U and A:T base pairs of 10 homologous RNA and DNA duplexes are compared. The isotope effect at 13C2 of adenosine residues due to deuterium/protium substitution at the imino H3 site, 2hDelta13C2, is larger in RNA than in DNA. The virtually consistent larger isotope effects in RNA suggest that the N1...N3 hydrogen bonds of A:U base pairs of RNA are stronger than those of the A:T base pairs of DNA. 相似文献
65.
Sorptivity data are reported for the capillary absorption of water, ethanol, propan-2-ol, and n-heptane by the calcitic limestone Lépine (Lavoux à grain). The data confirm that the water sorptivity is anomalously low, an indication of partial wetting by water. Results are expressed in terms of a wetting index. The water sorptivity increases after heat treatment and chemical oxidation by hydrogen peroxide bleaching, while the sorptivity with organic liquids is unchanged. These treatments, therefore, increase the water wetting index. The results provide strong evidence that the presence of a natural organic adlayer is responsible for the anomalously low water sorptivity of this particular limestone. This natural water repellency effect may be exploited in developing chemical treatments to modify the water transport properties of stone. 相似文献
66.
67.
Expeditious CuI-catalyzed conjugate 1,4-addition of bromo[2-(1,3-dioxolan-2-yl)ethyl]magnesium to the five-, six-, seven-, and eight-membered alpha,beta-cycloalkenones is described. The reaction times are decreased dramatically compared to CuBr-(CH(3))(2)S catalysis. The resulting ketoacetals were subsequently cyclized to bicyclic beta-hydroxy ketones and alpha,beta-enones, followed by further transformations. 相似文献
68.
Let G be a group and E an idempotent matrix with entries in the complex group algebra C
G. In this paper, we study arithmetic properties of the coefficients r
E
(g), gG, of the Hattori-Stallings rank r
E
of E. Bass proved in [2] that the r
E
(g)s are algebraic numbers. Following Zaleskii, we proceed by reduction to positive characteristic and give an alternative proof of that assertion, while obtaining at the same time an upper bound for the degree of the minimum polynomial of r
E
(g) over Q. 相似文献
69.
We establish that an ordered Banach space is order-isomorphic to c0 if and only if it is a -Dedekind complete vector lattice and its norm dual is order-isomorphic to 1. 相似文献
70.
Alexander B. Manenkov Ioannis G. Tigelis Angelos J. Amditis 《Optics Communications》2007,274(2):333-340
The diffraction phenomenon caused by metal transverse irises placed into an asymmetrical slab waveguide is examined by using the integral equation method. We concentrate on the possibility of controlling the radiation characteristics of the structure by changing the irises positions and the slab waveguide asymmetry. The aperture electric-field distribution is expressed in terms of a finite series of Chebyshev polynomials. The dominant TE guided-mode reflection and transmission coefficients, the near-field distribution and the far-field radiation pattern are calculated, while numerical results are presented for several cases of asymmetrical slab waveguides and different irises’ positions. 相似文献