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排序方式: 共有40条查询结果,搜索用时 140 毫秒
1.
C. Joly S. Goizet J. C. Schrotter J. Sanchez M. Escoubes 《Journal of membrane science》1997,130(1-2):63-74
The effect of introduction of silica particles prepared by the sol-gel technique on the gas transport properties of a polyimide film was studied. The sorption and permeation of N2, O2, CO2, H2 and CH4 were studied and correlated with morphological changes in the polymer structure. From sorption isotherms, we observed that the composite membrane presents higher solubility coefficients than the polyimide one. The solubility coefficient ratio between the composite and the polyimide is about 1.5–2.0. The isotherms were analyzed in terms of the dual mode sorption. The Henry's coefficient and the Langmuir's affinity and saturation constants were obtained allowing to calculate the Langmuir to Henry concentration ratios as function of the gas pressure. These ratios decrease until zero within a certain pressure range as long as the Langmuir's mode is acting and they are higher for the polyimide membrane when compared with the composite one. This study was completed with calorimetric measurements during the sorption. The gas interaction energy in kJ/mol decreases within the same pressure range as previously described. The measured energies are higher for the polyimide film when compared with the composite one because the polyimide membrane presents a stronger energetic effect caused by a higher Langmuir's contribution. From permeation studies at 3.155 Pa, the composite membrane showed higher permeability coefficients and permselectivities than the polyimide one. All these results were explained, taking into account the difference on the imidization degree of both membranes and the morphological changes which may be induced by the silica nodules in the organic/inorganic interphases. 相似文献
2.
Summary. Several compounds may exist in LnCl3–MCl mixtures. Those corresponding to the M
2
LnCl5 and MLn
2Cl7 stoichiometries are formed in a few systems only, with diverse stability strongly dependent on both the corresponding lanthanide
and alkali metal. On the other hand, M
3
LnCl6 that occur in most systems have a far larger stability range and melt congruently. These latter compounds were investigated
in the present work by differential scanning calorimetry and electrical conductivity measurements. The thermodynamic and transport
properties were correlated to structural features and related to the mechanism of compound formation.
Corresponding author. E-mail: Marcelle.Gaune-Escard@polytech.univ-mrs.fr
Received October 2, 2002; accepted November 6, 2002
Published online April 24, 2003
RID="a"
ID="a" This paper is dedicated to Professor H. Gamsj?ger on the occasion of his birthday 相似文献
3.
Paulovich FV Maki RM de Oliveira MC Colhone MC Santos FR Migliaccio V Ciancaglini P Perez KR Stabeli RG Perinoto AC Oliveira ON Zucolotto V 《Analytical and bioanalytical chemistry》2011,400(4):1153-1159
Recent advances in the control of molecular engineering architectures have allowed unprecedented ability of molecular recognition in biosensing, with a promising impact for clinical diagnosis and environment control. The availability of large amounts of data from electrical, optical, or electrochemical measurements requires, however, sophisticated data treatment in order to optimize sensing performance. In this study, we show how an information visualization system based on projections, referred to as Projection Explorer (PEx), can be used to achieve high performance for biosensors made with nanostructured films containing immobilized antigens. As a proof of concept, various visualizations were obtained with impedance spectroscopy data from an array of sensors whose electrical response could be specific toward a given antibody (analyte) owing to molecular recognition processes. In addition to discussing the distinct methods for projection and normalization of the data, we demonstrate that an excellent distinction can be made between real samples tested positive for Chagas disease and Leishmaniasis, which could not be achieved with conventional statistical methods. Such high performance probably arose from the possibility of treating the data in the whole frequency range. Through a systematic analysis, it was inferred that Sammon's mapping with standardization to normalize the data gives the best results, where distinction could be made of blood serum samples containing 10(-7) mg/mL of the antibody. The method inherent in PEx and the procedures for analyzing the impedance data are entirely generic and can be extended to optimize any type of sensor or biosensor. 相似文献
4.
O. Erriques M.T. Fogli Muciaccia S. Natali S. Nuzzo A. Halsteinslid K. Myklebost A. Rognebakke O. Skjeggestad S. Bonetti D. Cavalli A. Pullia M. Rollier G. Bonneaud B. Escoubes J.L. Guyonnet D. Huss M. Paty C. Racca A.G. Michette 《Physics letters. [Part B]》1977,70(3):383-386
Cross sections are presented for antineutrino production of Λ, Σ0 and K0 in strangeness changing reactions. Associated production reactions (ΔS = 0) have been observed in the charged and the neutral current channels. For the elastic reaction , estimates have been made of the axial transition form factor. 相似文献
5.
Journal of Thermal Analysis and Calorimetry - L'adsorption de vapeur d'eau sur montmorillonite lithique en provenance de Marnia et Camp Berteaux a été analysée après... 相似文献
6.
Blanka Kubikova Miroslav Boca Marcelle Gaune-Escard 《Monatshefte für Chemie / Chemical Monthly》2008,139(6):587-590
The phase equilibria in the K2TaF7–TaF5 binary system were determined up to x
TaF5 = 0.5 by means of differential scanning calorimetry. XRD diffraction analysis of solidified mixtures was performed. Besides
the K2TaF7 and KTaF6 phases, the presence of a third phase was observed, as well. It was suggested that the last phase melts incongruently.
Correspondence: B. Kubikova, Institute of Inorganic Chemistry SAS, Dúbravská cesta 9, Bratislava, 845 36, Slovakia. 相似文献
7.
High selectivity between oxygen and nitrogen has been found by gas permeation with doped polyaniline. Because of the small difference in kinetic diameters, solubility rather than diffusion may explain the preferential oxygen permeation. Electron spin resonance (ESR) measurements have been performed to check whether interactions of oxygen with polarons in polyaniline exist. A tenfold decrease in the spin number was observed when the polymer was in the presence of oxygen rather than nitrogen. This result was interpreted as being due to interactions between oxygen triplet states and polarons of polyaniline. 相似文献
8.
2-(Per-O-acetyl-β-d-glycopyranosyl)-1,4-dimethoxybenzenes led to C-glycosyl-hydroquinones suitable for preparing C-glycosylated analogs of vitamin E, having the sugar moiety free or acetylated. 相似文献
9.
Marcelle Gaune-Escard A. Bogacz L. Rycerz W. Szczepaniak 《Journal of Thermal Analysis and Calorimetry》1995,45(5):1117-1124
Present work is a part of thermodynamic research program on the MX?LnX3 system (M=alkali metal,X=Cl, Br andLn=lanthanide). Molar enthalpies of mixing in the LiBr?NdBr3, NaBr?NdBr3 and KBr?NdBr3 liquid binary systems have been determined at temperature 1063 K by direct calorimetry in the whole range of composition. Investigated systems are generally characterized by negative enthalpies of mixing with minimum atX NdBr3≈0.3–0.4. These enthalpies decrease with decrease of ionic radii of alkali metals. Molar enthalpies of solid-solid and solid-liquid phase transitions of K3NdBr6 and Cs3NdBr6 have been also determined by differential scanning calorimetry (DSC). K3NdBr6 is formed at 689 K from KBr and K2NdBr5 with enthalpy of 44.0 kJ·mol?1 whereas Cs3NdBr6 is stable at ambient temperature and undergoes phase transition in the solid state at 731 K with enthalpy of 8.8 kJ·mol?1. Enthalpies of melting have been also determined. 相似文献
10.
Marcelle Hauteville Rolf Stomberg Marie-Christine Duclos 《Journal of chemical crystallography》1999,29(6):681-685
Benzylation of 3-methylphloracetophenone [1-(2,4,6-trihydroxy-3-methylphenyl)ethanone] (3) with benzyl chloride gave 4-acetyl-2,6-dibenzyl-1,5-dihydroxy-2-methylcyclohexa-4,6-dien-3-one (5). Compound 5 crystallizes in the orthorhombic space group Fdd2 with a = 17.586(2), b = 42.891(5), c = 10.279(2) Å, V = 7753(2) Å,3 and Z = 16. When crystals of 5 were dissolved in [D6]acetone the compound underwent tautomerization and a mixture of 5 and its keto form 4 was obtained (keto form/enol form ratio 1:4). 相似文献