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131.
A sensitive analytical method for the determination of tetrodotoxin (TTX) in urine and plasma matrices was developed using double solid phase extraction (C18 and hydrophilic interaction liquid chromatography) and subsequent analysis by HPLC coupled with tandem mass spectrometry. The double SPE sample cleanup efficiently reduced matrix and ion suppression effects. Together with the use of ion pair reagent in the mobile phase, isocratic elution became possible which enabled a shorter analysis time of 5.5 min per sample. The assay results were linear up to 500 ng mL−1 for urine and 20 ng mL−1 for plasma. The limit of detection and limit of quantification were 0.13 ng mL−1 and 2.5 ng mL−1, respectively, for both biological matrices. Recoveries were in the range of 75-81%. To eliminate the effect of dehydration and variations in urinary output, urinary creatinine-adjustment was made. TTX was quantified in eight urine samples and seven plasma samples from eight patients suspected of having TTX poisoning. TTX was detected in all urine samples, with concentrations ranging from 17.6 to 460.5 ng mL−1, but was not detected in any of the plasma samples. The creatinine-adjusted TTX concentration in urine (ranging from 7.4 to 41.1 ng μmol−1 creatinine) correlated well with the degree of poisoning as observed from clinical symptoms. 相似文献
132.
We demonstrate that the Kohn-Sham self-consistent scheme used successfully for studying the electronic properties of periodic systems can be scaled to calculate the properties of quantum dots without and with constrictions at length and energy scales comparable to those currently attainable experimentally. This method can be a useful tool for studying low-dimensional systems in the extreme quantum limit. 相似文献
133.
By considering the now in a slider bearing to be a nearly viscometric flow we have examined the effects of variation in viscosity,
and normal stress differences on the total resistance and total normal force. We have found that under certain conditions
the normal stress differences may be neglected compared with the variation in viscosity. We have found that the effects of
variation in viscosity are to reduce the total resistance, and to increase or decrease the total normal force depending on
the ratio of the thickness of the liquid at the entry and exit. 相似文献
134.
A. V. Daniel J. H. Hamilton A. V. Ramayya A. S. Fomichev Yu. Ts. Oganessian G. S. Popeko A. M. Rodin G. M. Ter-Akopian J. K. Hwang D. Fong C. Goodin K. Li J. O. Rasmussen D. Seweryniak M. Carpenter C. J. Lister Sh. Zhu R. V. F. Janssens J. Batchelder J. Kliman L. Krupa W. -C. Ma S. J. Zhu L. Chaturvedi J. D. Cole 《Physics of Atomic Nuclei》2006,69(8):1405-1408
A new experiment devoted to the fission of 252Cf is described. It continued a series of our experiments based on correlation measurements of γ rays emitted by fission fragment pairs. The measurements of γ-γ and γ-γ-γ coincidences were done at Gammasphere with closed 252Cf sources. The open source was used for the first time in the last experiment. Fission fragment detectors were arranged in
the center hole of Gammasphere. Correlations between fission fragment masses, total kinetic energy, and γ rays were observed. The first, preliminary results of data analysis are discussed.
The text was submitted by the authors in English. 相似文献
135.
The synthesis of the rare bioactive phenylpropanoid ester known as cimiracemate B (1) from black cohosh, Cimicifuga racemosa, is described. The procedure employs a coupling method using 1, l'-carbonyldiimidazole and methyltrifluoromethanesulfonate as coupling reagents in the presence of N-methylmorpholine. 相似文献
136.
In this paper we consider the problem of identifying a parsimonious subset multivariate ARCH model based on the AIC principle.
The proposed approach can reduce the number of parameters in the final ARCH specification and allows for non-constant correlations
between the components. Some simulation results illustrate the viability of the proposed procedure. 相似文献
137.
Lee Kai Fong 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1974,2(3):187-192
The theories of two decay-type parametric instabilities involving the lower hybrid mode in a magnetized plasma are presented. In the first of these, a pump wave of ordinary polarization causes the growth of a backward propagating transverse wave and a longitudinal lower hybrid wave, all with wave vectors perpendicular to the external magnetic field. The second instability concerns the parametric excitation of the upper hybrid and the lower hybrid modes. 相似文献
138.
The microwave spectra of three isotopic species of methoxyamine (CH3ONH2) have been studied. For the normal species the ground-state rotational constants are A = 42488 ± 150 MHz, B = 10049.59 ± 0.03 MHz, and C = 8962.85 ± 0.03 MHz. From these data and those from the -NHD and -ND2 species, the amino protons have been shown to occupy a symmetrical trans position relative to the methyl group. The barrier to internal rotation of the methyl group has been found to be 873 ± 15 cm?1 by analysis of ground-state splittings. Analysis of hyperfine splittings has yielded the 14N quadrupole coupling constants, which have the following values for the normal isotopic species: χaa = 3.63 ± 0.03 MHz, χbb = ?3.69 ± 0.07 MHz, and χcc = 0.06 ± 0.07 MHz. 相似文献
139.
140.
M. Piccolo I. Peruzzi P.A. Rapidis A. Barbaro-Galtieri J.M. Feller D. Lüke V. Vuillemin J.M. Dorfan R. Ely G.J. Feldman A. Fong B. Gobbi G. Hanson J.A. Jaros B.P. Kwan P. Lecomte A.M. Litke R.J. Madaras D.E. Yount 《Physics letters. [Part B]》1979,86(2):220-224
We present measurements of the cross section for inclusive D and K meson production in e+e? annihilation in the center of mass energy range 3.6 to 5.8 GeV. D production accounts for most of the increase in the total cross section for hadron production in e+e? annihilation at energies above 4 GeV. 相似文献