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排序方式: 共有88条查询结果,搜索用时 249 毫秒
51.
52.
Y. Le Vaillant C. Brenier Y. Grange A. Nicolas P. A. Bonnet L. R. Massing-Bias P. Rakotomanga B. Koumaré A. Mahly M. Absi M. Ciss M. H. Loueslati D. Chauvey 《Chromatographia》2012,75(11-12):617-628
The fixed-dose combination artesunate (AS)–amodiaquine (AQ) is one of the most widely used treatments for uncomplicated falciparum malaria. It is currently proposed to the inclusion in the model list of essential medicines of World Health Organization and has been recently prequalified. Until now, no satisfactory method for the simultaneous determination of the two active ingredients had been available. Thus, a reversed phase high performance liquid chromatography for the quantitative determination of AQ and AS was developed and validated. Chromatography was performed using an end-capped octadecylsilyl silica gel column (100?×?4.6?mm, 3?μm) with a binary gradient using aqueous phase containing potassium dihydrogen phosphate (10?mM) and acetonitrile. Taking into consideration the physico-chemical characteristics of the two compounds related to their ionization, the use of a counter ion was necessary to ensure the retention of AQ in a reversed phase system simultaneously to AS. Thus, aqueous mobile phase was adjusted to pH 3.0 and the chosen counter ion was sodium 1-octanesulfonate (100?mM). In these conditions, the retention times were about 4?min for AQ and 10?min for AS with UV detection at 300 and 210?nm, respectively. Method was then validated according to ICH guideline (specificity/linearity/accuracy/precision) and potential interferences with excipients and degradation products were checked. It has also been used for an interlaboratory study involving seven African National Quality Control Laboratories and Afssaps (Agence fran?aise de sécurité sanitaire des produits de santé) laboratory. The results demonstrate that this rapid and simple method can be easily used by official laboratories for routine control, market survey and for the detection of potential substandard medicines which are very frequent in African countries. 相似文献
53.
F. Grange C. Delaveaud B. Viala K. Mahdjoubi 《Applied Physics A: Materials Science & Processing》2011,103(3):581-585
In the present paper we study the effect of high-permeability self-polarized thin films on the characteristics of high-impedance
surfaces. Analytical and numerical models are compared by using the anisotropic effective medium theory method and a full-wave
simulation tool, respectively. Experimental measurements are shown and lead to a good agreement with both numerical and analytical
calculations. The main objective of this paper is to predict the impact of the permeability and conductivity of the material
on artificial magnetic conductor structures. 相似文献
54.
A series of diimine-tetracyanoosmate anions [Os(diimine)(CN)4]2- [diimine=2,2'-bipyridine (bipy), 2,2'-bipyrimidine (bpym), 1,10-phenanthroline (phen), and 4,4'-tBu2-2,2'-bipyridine (tBu2bpy)] were prepared and isolated as their Na+ salts (water soluble) or PPN+ salts (soluble in organic solvents). Several examples were crystallographically characterized; the Na+ salts form a range of 1D, 2D, or 3D infinite coordination polymers via coordination of the cyanide groups to Na+ cations in either an end-on or a side-on manner. The [Os(diimine)(CN)4]2- anions are solvatochromic, showing three MLCT absorptions, which are considerably blue-shifted in water compared to organic solvents, in the same way as is well-known for the analogous [Ru(diimine)(CN)4]2- anions. Luminescence in the red region of the spectrum is very weak but (following the expected solvatochromic behavior) is higher energy and more intense in water. However, by exploiting the effect of metallochromism (ref 4), the emission from [Os(tBu2bpy)(CN)4]2- in MeCN can be very substantially boosted in energy, intensity, and lifetime in the presence of Lewis-acidic metal cations (Na+, Ba2+, Zn2+), which, in a relatively noncompetitive solvent, coordinate to the cyanide groups of [Os(tBu2bpy)(CN)4]2-. This has an effect similar in principle to hydrogen bonding of the cyanides to delta+ protons of water, but very much stronger, such that in the presence of Zn2+ ions in MeCN the 1MLCT and 3MLCT absorptions are blue-shifted by ca. 7000 cm(-1), and the luminescence moves from 970 nm (vanishingly weak) to 610 nm with a lifetime of 120 ns (dominant component). Thus, the binding of metal cations to the cyanides provides a mechanism to incorporate [Os(diimine)(CN)4]2- complexes into polynuclear assemblies and simultaneously increases their 3MLCT energy and lifetime to an extent that makes them comparable to much-stronger luminophores such as Ru(II)-polypyridines. 相似文献
55.
We present evidence for a nonsingular origin of the Universe with intial conditions determined by quantum physics and relativistic
gravity. In particular, we establish that the present temperature of the microwave background and the present density of the
Universe agree well with our predictions from these intial conditions, after evolution to the present age using the Einstein-Friedmann
equation. Remarkably, the quantum origin for the Universe naturally allows its evolution at exactly the critical density.
We also discuss the consequences of these results to some fundamental aspects of quantum physics in the early Universe. 相似文献
56.
57.
58.
M. Berlanger P. Grange H. Hofmann C. Ngô J. Richert 《Zeitschrift für Physik A Hadrons and Nuclei》1978,285(2):207-214
Highly excited levels of33S populated by α-particle capture in29Si have been investigated forE α=1.962 MeV to 4.287 MeV. Excitation curves measured with Ge(Li) and BF3 detectors are reported. More than fifty resonances can be identified with levels in33S. (α, γ) angular distributions measured on five strong resonances have yieldedJ π values 1/2+, 3/2 +, 5/2?, 5/2?, 5/2? and 3/2+ respectively, for theE x =10.054, 10.466, 10.523, 10.721, 10.758 and 10.776 MeV levels in33S. Elastic scattering experiments have been performed and theJ π assignments are found to be consistent with thel-values inferred from the elastic scattering data. Decay schemes from the above33S levels have been proposed. A new level at 9.245 MeV is also suggested and theJ π values for the 4.425 and 2.87 MeV states are shown to be consistent with 7/2+ and 3/2+ assignment, respectively. Nuclear Reactions29Si(α, γ) and29Si(α, α),E α=1.962-4.287 MeV. Measured relative σ(E). DeducedJ π andE γ of33S levels. New33S level atE x =9.245 MeV. Enriched targets. 相似文献
59.
GYÖRGY TARCZAY ATTILA G. CSÁSZÁR WIM KLOPPER HARRY M. QUINEY 《Molecular physics》2013,111(21):1769-1794
Relativistic energy corrections which arise from the use of the Dirac-Coulomb Hamiltonian, and the Gaunt and Breit interaction operators, plus Lamb-shift effects have been determined for the global minima of the ground electronic states of C2H6, NH3, H2O, [H,C,N], HNCO, HCOOH, SiC2, SiH? 3, and H2S, and for barrier characteristics for these molecular systems (inversion barrier of NH3 and SiH? 3, barrier to linearity of H2O, H2S, and HNCO, rotational barrier of C2H6, difference between conformations of HCOOH (Z/E) and SiC2 (linear/T-shaped), and isomerization barrier of HCN/HNC). The relativistic calculations performed at the Hartree-Fock and the highly correlated CCSD(T) levels employed a wide variety of basis sets. Comparison of the perturbational and the four-component fully variational results indicate that the Coulomb-Pauli Hamiltonian and the lowest order Hamiltonian of direct perturbation theory (DPT(2)) are highly successful for treating the relativistic energy effects in light molecular systems both at a single point on the potential energy hypersurface and along the surface. Electron correlation contributions to the relativistic corrections are relatively small for the systems studied, and are comparable with the 2-electron Darwin correction. Corrections beyond the Dirac-Coulomb treatment are usually rather small, but may become important for high accuracy ab initio calculations. 相似文献
60.
P. Gajardo D. Pirotte C. Defosse P. Grange B. Delmon 《Journal of Electron Spectroscopy and Related Phenomena》1979,17(2):121-135
XPS results on two series of catalysts, namely Mo/SiO2 and CoMo/SiO2 in the oxidic form, are reported. In the first series the molybdenum oxide content deposited on SiO2 ranges from 2.8 to 20.6 weight %. The second series was obtained by cobalt impregnation of the first series; in this case the atomic ratio Co/(Co + Mo) was fixed at 0.36.XPS binding energy and intensities measurements enable estimation of the interaction and dispersion between the oxide phase and the support to be made.In the case of molybdenum deposited alone on the support, the binding energies of the Mo and O levels both increase with MoO3 content. When cobalt is also present on the support, the binding energies of the Mo and O levels remain constant. The relative intensities IMo/ISi and ICo/ISi remain constant up to 12% active phase and then drastically increase for higher amounts of oxide.These results confirm the existence of a relatively strong Mo/SiO2 interaction. This interaction is substantially weaker when Co is supported on the MoSiO2 solid, leading to the formation of CoMoO4 at the expense of the Mo/SiO2 interaction. Furthermore, it is shown that at high content of oxide the active phase is deposited on the outer surface of the particle and not inside the pores. 相似文献