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171.
A sensitive system for D,L-amino acid analysis has been developed, using fluorescence derivatization with o-phthaldialdehyde in the presence of sodium salt of 1-thio-beta-D-glucose. The reagents rapidly form fluorescent diastereoisomeric derivatives with primary amino acids. These derivatives are efficiently separated on a conventional reversed-phase column with an analysis time of 60 min. Simultaneous determination of enantiomers of various amino acids was achieved by a simple binary gradient elution with methanol in 0.05 M aqueous sodium acetate. 相似文献
172.
T. Anticic B. Baatar J. Bartke L. Betev H. Bia?kowska B. Boimska J. Bracinik V. Cerny O. Chvala J. Dolejsi V. Eckardt H. G. Fischer Z. Fodor E. G?adysz K. Kadija A. Karev V. Kolesnikov M. Kowalski M. Kreps M. Makariev A. Malakhov M. Mateev G. Melkumov A. Rybicki N. Schmitz P. Seyboth T. Susa P. Szymanski V. Trubnikov D. Varga G. Vesztergombi S. Wenig 《The European Physical Journal C - Particles and Fields》2010,68(1-2):1-73
New data on the production of charged kaons in p+p interactions are presented. The data come from a sample of 4.8 million inelastic events obtained with the NA49 detector at the CERN SPS at 158 GeV/c beam momentum. The kaons are identified by energy loss in a large TPC tracking system. Inclusive invariant cross sections are obtained in intervals from 0 to 1.7 GeV/c in transverse momentum and from 0 to 0.5 in Feynman x. Using these data as a reference, a new evaluation of the energy dependence of kaon production, including neutral kaons, is conducted over a range from 3 GeV to $\mathrm{p}+\overline{\mathrm{p}}$ collider energies. 相似文献
173.
Stere?Ianu?Email author Renzo?Mazzocco Gabriel?Eduard?V?lcu 《Mediterranean Journal of Mathematics》2006,3(3-4):581-592
The main purpose of this paper is to give basic properties of real lightlike hypersurfaces of paraquaternionic manifold and
to prove the nonexistence of real lightlike hypersurfaces in paraquaternionic space forms under some conditions.
Dedicated to the memory of Professor Aldo Cossu 相似文献
174.
175.
Herminio Martínez Eva Vidal Eduard Alarcón Alberto Poveda 《Analog Integrated Circuits and Signal Processing》2009,61(3):231-246
Continuous-time filters with automatic tuning loops are nonlinear feedback systems that are potentially unstable. To ensure
stability, particularly if the design of the loop controllers is to be improved, the appropriate linear dynamic modeling of
the tunable filter, including control inputs, should be attained. This work aims to present a general dynamic modeling of
continuous-time analog filters with automatic tuning capability. The general analysis leads to an equivalent small-signal
linearized incremental model, from which transfer functions between output variables and control voltages are obtained. Subsequent
to the analysis, it is possible to design compensated loops with enhanced stability and dynamic performance. By way of example,
the modeling of a particular band-pass CMOS continuous-time analog filter is presented in this paper. Two transfer functions
are derived: the transfer function between the output phase shift and the central frequency control voltage, and that between
the output amplitude and the quality factor control voltage. These functions are required to properly tune the central frequency
and quality factor parameters. This modeling makes it possible to propose an adaptive controller with improved stability and
a possible implementation for such a controller. Finally, experimental results are shown for a CMOS 0.8 μm technology. 相似文献
176.
Eduard Grasa Sergi Figuerola Albert Forns Gabriel Junyent 《Optical Switching and Networking》2009,6(2):120-128
Data-intensive high performance, high quality digital media traffic cannot be accommodated on traditional Layer 3 networks. Alternative technologies to transmit this traffic through the network, such as optical multicast, are being investigated. A prototype of an optical multicast service was showcased during the 7th Annual LambdaGrid Workshop celebrated in Prague last September. The prototype used Time Division Multiplexing (TDM) technology as the data plane and Argia (the evolution of UCLP) as the control/service plane. This paper describes the extensions that were done to the Argia Software to provide the Dynamic Optical Multicast Service and shows the results achieved during the Prague demonstration. 相似文献
177.
Baer M Schreiner E Kohlmeyer A Rousseau R Marx D 《The journal of physical chemistry. B》2006,110(8):3576-3587
The inverse temperature transition (ITT) of a biomimetic model for elastin, capped GVG(VPGVG) in liquid water, is investigated by a comprehensive classical molecular dynamics study. The temperature dependence of the solvation structure and dynamics of the octapeptide are compared using three common force fields, CHARMM, GROMOS, and OPLS. While these force fields differ in quantitative detail, they all predict this octapeptide to undergo a "folding transition" to closed conformations upon heating and a subsequent "unfolding transition" to open conformations at still higher temperatures, thus reproducing the ITT scenario. The peptide kinetics is analyzed within the reactive flux formalism applied to the largest-amplitude mode extracted from principal component analysis, and the solvent's dielectric fluctuations are obtained from the total water dipole autocorrelations. Most importantly, preliminary evidence for an intimate coupling of peptide folding/unfolding dynamics, and thus the ITT, and dielectric relaxation of bulk water is given, possibly being consistent with a "slave mode" picture. 相似文献
178.
Ogienko AG Kurnosov AV Manakov AY Larionov EG Ancharov AI Sheromov MA Nesterov AN 《The journal of physical chemistry. B》2006,110(6):2840-2846
For the first time, the compositions of argon and methane high-pressure gas hydrates have been directly determined. The studied samples of the gas hydrates were prepared under high-pressure conditions and quenched at 77 K. The composition of the argon hydrate (structure H, stable at 460-770 MPa) was found to be Ar.(3.27 +/- 0.17)H(2)O. This result shows a good agreement with the refinement of the argon hydrate structure using neutron powder diffraction data and helps to rationalize the evolution of hydrate structures in the Ar-H(2)O system at high pressures. The quenched argon hydrate was found to dissociate in two steps. The first step (170-190 K) corresponds to a partial dissociation of the hydrate and the self-preservation of a residual part of the hydrate with an ice cover. Presumably, significant amounts of ice Ic form at this stage. The second step (210-230 K) corresponds to the dissociation of the residual part of the hydrate. The composition of the methane hydrate (cubic structure I, stable up to 620 MPa) was found to be CH(4).5.76H(2)O. Temperature dependence of the unit cell parameters for both hydrates has been also studied. Calculated from these results, the thermal expansivities for the structure H argon hydrate are alpha(a) = 76.6 K(-1) and alpha(c) = 77.4 K(-1) (in the 100-250 K temperature range) and for the cubic structure I methane hydrate are alpha(a) = 32.2 K(-1), alpha(a) = 53.0 K(-1), and alpha(a) = 73.5 K(-1) at 100, 150, and 200 K, respectively. 相似文献
179.
180.
Considering compressible Navier–Stokes system in a slab geometry in the regime when both Mach and Froude numbers vanish at the same rate, we study the behavior of corresponding weak solutions, that are known to exist globally-in-time (for large data). We establish their convergence to a solution of the so-called anelastic approximation when the limit flow is stratified, i.e., the limit density depends effectively on the vertical coordinate. 相似文献