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981.
R Bagnati M Paleologo Oriundi V Russo M Danese F Berti R Fanelli 《Journal of chromatography. A》1991,564(2):493-502
A method for the determination of zeranol and its metabolite beta-zearalanol in bovine urine is described. It has been applied to samples from calves given multiple subcutaneous doses of zeranol. Samples were extracted with immunoaffinity columns containing antibodies raised against zeranol and were analysed by gas chromatography-mass spectrometry. The immunoaffinity columns were prepared by coupling immunoglobulin G fractions obtained from rabbit antisera with a Sepharose matrix. The immunizing agent was carboxybutylzeranol coupled to bovine serum albumin. Gas chromatography-mass spectrometry was performed in the negative-ion chemical ionization mode, after derivatization of the compounds to their pentafluorobenzyl ethers, and allowed detection of analytes with a sensitivity of 0.01 ppb in spiked urine. The derivatization method and the gas chromatographic determination were also applied to the similar compounds zearalanone, zearalenone and beta-zearalenol. A synthesis of dideuterated zeranol and beta-zearalanol by isotopic exchange is described. These deuterated analogues had an isotopic purity of more than 99% and were used for quantitation of zeranol and beta-zearalanol by isotope dilution mass spectrometry. The recoveries of zeranol and beta-zearalanol, using the immunoaffinity columns, were determined after extraction from spiked urine and were 84 and 64%, respectively. The urines of treated calves were collected for several days after treatments and were analysed after hydrolysis with beta-glucuronidase and arylsulphatase. The samples showed variable but generally decreasing concentrations of zeranol and beta-zearalanol. The levels of beta-zearalanol ranged from less than 0.01 to 98 ppb and were 1.2-3.2 times higher than those of zeranol. 相似文献
982.
An opto-electronic cross-correlation system was employed to reduce the scattering influence in fluorescence measurements. A stable optical delay line incorporated into the instrument was positioned to yield detection at a fixed time after excitation; the optimal delay time was determined simply from the ratio of the fluorescence decay curve to a similar curve portraying scattering response. Signal-to-scattering background enhancements greater than two were measured for the very short-lived (τ = 0.7 ns) fluorophores whereas a six-fold increase was measured for fluorophores with longer lifetimes. The shortest lifetime which would benefit from time-resolution in this system is limited by the time-response of the photomultiplier tube (1.1 ns FWHM); the excitation pulses are on the order of 6 ps. 相似文献
983.
G. Mastroianni M. G. Russo W. Themistoclakis 《Integral Equations and Operator Theory》2002,42(1):57-89
The mapping properties of the Cauchy singular integral operator with constant coefficients are studied in couples of spaces equipped with weighted uniform norms. Recently weighted Besov type spaces got more and more interest in approximation theory and, in particular, in the numerical analysis of polynomial approximation methods for Cauchy singular integral equations on an interval. In a scale of pairs of weighted Besov spaces the authors state the boundedness and the invertibility of the Cauchy singular integral operator. Such result was not expected for a long time and it will affect further investigations essentially. The technique of the paper is based on properties of the de la Vallée Poussin operator constructed with respect to some Jacobi polynomials. 相似文献
984.
Applied Biochemistry and Biotechnology - 相似文献
985.
A. Di Chiara F. Lombardi F. Miletto Granozio F. Tafuri M. Valentino S. Pagano B. Ruggiero M. Russo 《Il Nuovo Cimento D》1994,16(12):1999-2004
Summary YBCO step-edge junction d.c. SQUIDs have been realized by using the Inverted Cylindrical Magnetron Sputtering (ICMS) technique.
This last represents a novel technology for high-T
c Josephson junctions (HTSC). Steps are obtained by standard ion milling procedure on LaAlO3 (100) substrates using Nb-masks patterned by reactive ion etching. Measurements of currentvs. voltage, maximum d.c. Josephson currentvs. magnetic field and SQUID voltage response measurements have been performed, also as a function of the temperature. Operating
temperature as high as 77K has been achieved. At 4.2K the SQUIDs show a maximum voltage of flux transfer function (∂V/∂ϕ)max=870 μV/Ф0 and a good periodicity of theV-ϕ modulation up to 20Ф0 without any sign of hysteresis. The ratio between the step height (h) and the film thickness (d) seems to play a fundamental role in determining Josephson properties of the bridges, these conditions being more severe
with respect to most of the data available in literature.
Paper presented at the ?VII Congresso SATT?, Torino, 4–7 October 1994. 相似文献
986.
A. Del Vecchio C. Camerlingo F. De Riccardis H. Huang B. Ruggiero M. Russo E. Sarnelli M. A. Tagliente L. Tapfer G. Testa 《Il Nuovo Cimento D》1994,16(12):2025-2030
Summary We present a structural analysis of YBCO superconducting thin films fabricatedin situ by Inverted Cylindrical Magnetron (ICM) sputtering on commercial SrTiO3 single-crystal and bicrystal substrates. A detailed structural characterization of the superconductor films was performed
by using single-crystal X-ray diffractometry confirming that YBCO films have a strongc-axis orientation of the grains with a small mosaic spread. In the films grown on bicrystal substrates we observed a strong
correlation with the lattice structure of the substrate. In addition, a surface analysis of the region across the grain boundary
edge has been performed by using scanning electron microscopy.
Paper presented at the ?VII Congresso SATT?, Torino, 4–7 October 1994. 相似文献
987.
988.
989.
Yury Abashkin Nino Russo Marirosa Toscano 《International journal of quantum chemistry》1994,52(4):695-704
Three representative isomerization reactions (HNC → HCN, CH3NC → CH3CN, and N2H2 trans → cis and sin) have been studied using both the LCGTO–LSD and LCGTO–NLSD density functional methods and employing a new algorithm for the search and the refinement of the transition-state structures. The inclusion of the nonlocal corrections and the use of large basis sets improve the reliability of the energetic parameters. Results are in good agreement with previous accurate first-principle computations and available experimental data. © John Wiley & Sons, Inc. 相似文献
990.