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991.
992.
Carbon disulfide (CS2) was determined at trace levels by its induction effect on the reaction of triiodide with azide in acidic media. The reaction was monitored spectrophotometrically by the decreased absorbance of triiodide over a period of 30 - 180 s from the initiation of the reaction at 350 nm, with calibration linear range of 0.020 - 1.870 microg/ml CS2. The limit of detection is 0.013 microg/ml CS2. A carbon-active column was used for sample solution clean up. The proposed method was successfully applied to the determination of trace carbon disulfide in natural water. 相似文献
993.
The two-dimensional Laplace integral transform technique has been applied to get the spatial and temporal temperature distributions in both the molten layer thickness of a thin film coated on a substrate, the still solid part of the thin film of the target and the temperature distribution in the substrate. Also a formula for the time dependence of the evaporated part of the thin film of the target as well as the molten layer thickness of the thin film were obtained. Calculations of the obtained relations were carried out during the irradiation with a pulsed laser. The derivation has taken into account the temperature-dependent absorption coefficient of the irradiated surface and the chemical reaction in the vapor of the thin film. As an illustrative example, computations were carried out on an aluminum thin film coated on a glass substrate. 相似文献
994.
A. Sh Ghazal M. S. M. Nour El-Din M. Y. M. Hassan 《The European Physical Journal A - Hadrons and Nuclei》2004,19(2):221-229
A linear form of density-dependent total nucleon-nucleon (NN) cross-section that depends on the coordinates of the projectile and target is applied in the Glauber phase shift formula. The only free parameter in these calculations is the density-dependent parameter
, which is adjusted to obtain an agreement between the calculated angular distribution of the elastic-scattering cross-section and the corresponding experimental one. The elastic scattering of the 12C ion on the 12C ion target has been studied at incident energies of 300, 360, 1016, 1441 and 2400 MeV. The total reaction cross-section
is also calculated with the obtained value of
for the same reactions. The obtained values of
are compared with those obtained from the optical-model analysis as well as those of the experimental value. Nuclear transparency effects are also discussed. Generally, the density-dependent NN cross-section improves the calculated results.Received: 11 February 2003, Revised: 8 July 2003, Published online: 26 January 2004PACS:
24.10.-i Nuclear-reaction models and methods - 25.70.-z Low and intermediate energy heavy-ion reactions 相似文献
995.
Ultrathin films of chiral polyelectrolyte complex, prepared by the multilayering process, exhibit selectivity in the membrane separations of optically active compounds, such as l- and d-ascorbic acid. The flux through these polyelectrolyte multilayers, PEMUs, is exceptionally high and may be controlled by the concentration of salt present in the permeating solutions. Both in-situ ATR-FTIR and chiral capillary electrochromatography indicate that flux selectivity is mainly kinetically controlled, stemming from a difference in diffusion rates of various enantiomers through PEMUs, rather than a difference in partitioning. 相似文献
996.
Hassan A. El-Morshedy S.R. Grace 《Journal of Mathematical Analysis and Applications》2005,306(1):106-121
New oscillation results are obtained for the second order nonlinear difference equation
Δ(rnf(Δxn−1))+g(n,xn)=0, 相似文献
997.
We propose an interaction-induced cooling mechanism for two-component cold fermions in an optical lattice. It is based on an increase of the spin entropy upon localization, an analogue of the Pomeranchuk effect in liquid helium 3. We discuss its application to the experimental realization of the antiferromagnetic phase. We illustrate our arguments with dynamical mean-field theory calculations. 相似文献
998.
A. H. Khater M. M. Hassan E. V. Krishnan Y. Z. Peng 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,50(2):177-184
New several classes of exact solutions are obtained in terms of the
Weierstrass elliptic function for some nonlinear partial
differential equations modeling ion-acoustic waves as well as dusty
plasmas in laboratory and space sciences. The Weierstrass elliptic
function solutions of the Schamel equation, a fifth order dispersive
wave equation and the Kawahara equation are constructed. Moreover,
Jacobi elliptic function solutions and solitary wave solutions of
the Schamel equation are also given. The stability of some periodic
wave solutions is computationally
studied. 相似文献
999.
Vytras K Khaled E Jezková J Hassan HN Barsoum BN 《Fresenius' Journal of Analytical Chemistry》2000,367(2):203-207
Construction, performance characteristics and applications of a carbon paste thallium(III) ion-selective electrode are described. The electrode, which is based on ion-associate compounds formed between cetylpyridinium and chlorothallate(III) complexes dissolved in tricresyl phosphate as pasting liquid, showed near-Nernstian response over the concentration range of 5.8 x 10(-6) - 2.9 x 10(-3) mol/L. Potentiometric titrations of thallium(III) with cetylpyridinium chloride were affected by higher concentrations of excess halides, probably due to the formation of higher halogenothallates. 相似文献
1000.
For a finite morphism f : X Y of smooth varieties such that f maps X birationally onto X=f(X), the local equations of f are obtained at the double points which are not triple. If C is the conductor of X over X, and
are the subschemes defined by C, then D and are shown to be complete intersections at these points, provided that C has the expected codimension. This leads one to determine the depth of local rings of X at these double points. On the other hand, when C is reduced in X, it is proved that X is weakly normal at these points, and some global results are given. For the case of affine spaces, the local equations of X at these points are computed. 相似文献