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991.
992.
993.
The equilibria between tungsten(VI) and iminodiacetic acid (IDA) have been studied in aqueous solution. The stoichiometry
and stability constants of the complexes formed are determined from a combination of potentiometric and Uv spectroscopic measurements.
All measurements are carried out at 25°C, pH 7.5 and different ionic strengths ranging from (0.1 to 1.0) mol dm−3 (NaClO4). According to these results, tungsten(VI) forms a mononuclear complex with IDA of the type (WO3L2−). By introducing two empirical parameters C and D in the complex-formation reaction between tungsten(VI) and IDA, the dependence
of the dissociation and stability constants on ionic strength is described by a modified Debye-Huckel-type equation. Finally,
a pattern for the ionic strength dependence is obtained. 相似文献
994.
995.
M. Henriksson L. Sjöqvist V. Pasiskevicius F. Laurell 《Applied physics. B, Lasers and optics》2007,86(3):497-501
An optical parametric oscillator using a periodically poled LiNbO3 crystal and a volume Bragg grating output coupler is presented. Signal and idler wavelengths of 2008 and 2264 nm were generated
from the 1064 nm Nd:YVO4 pump laser. The Bragg grating was reflecting in a narrow band around 2008 nm, creating a purely singly resonant cavity. Signal
and idler linewidths of approximately 0.44 and 0.72 nm, respectively, were measured. This is a reduction of 80 and 60 times
compared to when using a mirror as output coupler. A total output energy of 156 μJ was measured with 47% slope efficiency.
PACS 42.65.Yj; 42.72.Ai; 42.40.Eq 相似文献
996.
We propose a general idea of obtaining different chains of coupled oscillators with chaotic buffering. As examples, we consider chains of diffusively coupled generalized cubic Schrödinger equations and nonlinear telegraph equations. We also give examples of systems that have an infinite-dimensional chaotic attractor. 相似文献
997.
Y. Zhao W.C. Zhai W.L. Seah K.Y. Lim F.C. Cheong C.H. Sow 《Applied physics. B, Lasers and optics》2007,87(2):243-247
A study of the variation of the spectral shape and the harmonic distribution of the high-order harmonics generated from silver
plasma on the frequency chirp of the driving laser radiation (793 nm 48 fs) is reported. The results of the systematic study
of the harmonic generation from the 21st order up to the 61st order (λ=13 nm) are presented. A tuning of the harmonic wavelength
up to 0.8 nm can be accomplished by variation of the laser chirp.
PACS 42.65.Ky; 42.79.Nv; 52.38.Mf 相似文献
998.
M. López Granados F. Cabello Galisteo M. Alifanti J.L.G. Fierro 《Applied Surface Science》2006,252(24):8442-8450
This work reports the research carried out by studying aliquots extracted at different axial coordinates from Three Way Catalyst (TWC) monoliths aged under real traffic conditions. Our study focused on the catalytic properties and on several chemical and physical effects caused in the Front and Rear monolith washcoat surfaces by vehicle aging after 60,000 km. Regarding the catalytic properties, all the used aliquots showed poorer activity than their corresponding fresh counterparts. The strongest deactivation was detected for NO and hydrocarbon conversion. CO conversion was less affected and the Rear monolith was as deactivated as the Front one. The characterisation techniques (TXRF, N2 adsorption-desorption isotherms, XRD and H2-TPR) detected - (i) the deposition of P, Zn and Pb; (ii) the formation of CePO4 on account of the Ce from the washcoat; (iii) thermal sintering; (iv) inhibition of the reducibility of Ce oxides - as the main effects brought about by vehicle aging conditions. The deactivation observed at the beginning of the Front monolith was the result of a combination of the former effects. When moving downstream to higher axial coordinates, Pb accumulation and the loss of specific area appeared to be the only probable sources of deactivation. 相似文献
999.
A theory of a low-pressure discharge in a xenon-molecular hydrogen mixture is developed. It is shown that, in such a discharge, at an interelectrode distance of L = 1 cm and a total plasma pressure of p 0 ~ 1 Torr, the density of negative hydrogen ions produced via the dissociative attachment of thermal electrons to vibrationally excited molecules H2 can reach a value as high as NH ? ≥ 1012 cm?3. According to calculations, the electron temperature in discharge operating regimes under study attains T e ≈ 1?2 eV, which corresponds to the maximum of the e-v exchange rate constant of H2 molecules. This ensures a relatively high rate of vibrational pumping of H2 molecules in the discharge. 相似文献
1000.
G. M. Pavlov I. I. Zaitseva A. S. Gubarev I. I. Gavrilova E. F. Panarin 《Russian Journal of Applied Chemistry》2006,79(9):1490-1493
Samples of sodium polystyrenesulfonate of molecular weights varying in a 20-fold range were synthesized. The hydrodynamic behavior of the samples was studied in a 0.2 M NaCl solution in which the initial polyelectrolyte effects are suppressed. Relationships between the molecular weight and the translational friction coefficient and intrinsic viscosity were obtained. The theory describing the hydrodynamic behavior of wormlike chains with taking into account both the percolation effects and the excluded-volume effects was applied to estimation of the length of the statistical segment and the cross section of the sodium polystyrenesulfonate molecules in 0.2 M NaCl solution. 相似文献