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Adsorption of Hydrophobically Modified Polyelectrolytes on Hydrophobic Substrates Adsorption de polyélectrolytes modifiés hydrophobiquement sur les substrats hydrophobes  [cached]
Mays J. W.,Zhang Y.,Tirrell M.
Oil & Gas Science and Technology , 2006, DOI: 10.2516/ogst:1997016
Abstract: A series of diblock copolymers, poly (tert-butyl styrene)-sodium poly (styrene sulfonate) with different molecular weight and percentage of sulfonation have been used to study the effect of polymer structure on its adsorption behavior onto hydrophobically modified silicon wafers. The percentage of the hydrophobic block varies from 3. 6-8. 9%. Previous studies show that salt concentration is very important for the adsorption of such polyelectrolytes onto silica surfaces. Octadecyltriethoxysilane (OTE) has been used to modify the silicon wafer which changes the water contact angle from 50° on unmodified silica to 100° to 120°. On this hydrophobic surface, we found that the adsorption of these slightly hydrophobically modified polyelectrolytes is close to the 4/23rd power of salt concentration predicted by a recent model. The grafting density is also consistent with a dependence on the length of the hydrophobic block to the -12/23rd power, and the length of the polyelectrolyte block to the -6/23rd power, predicted by this model. Une série de copolymères à diblocs poly (tert-butyle styrène)-sodium (sulfonate de polystyrène) de masses moléculaires et pourcentages de sulfonation différents ont été utilisés pour étudier les effets de la structure du polymère sur son pouvoir d'adsorption sur des surfaces de silicium modifiées hydrophobiquement. Le pourcentage du bloc hydrophobe varie de 3,6 à 8,9%. Les études antérieures montrent que la concentration saline est très importante pour l'adsorption de ces polyélectrolytes sur les surfaces de silice. Nous avons utilisé l'octadecyltriéthoxysilane (OTE) pour modifier la surface de silicium qui change l'angle de contact de l'eau de 50° sur la silice non modifiée à une valeur comprise entre 100° et 120° sur la silice modifiée. Sur cette surface hydrophobe, nous constatons que l'adsorption de ces polyélectrolytes légèrement modifiés hydrophobiquement est proche de la loi puissance 4/23 avec la concentration saline prédite par un modèle récent. La densité d'implantation est également cohérente avec une dépendance à la longueur du bloc hydrophobe à la puissance - 12/23, et à la longueur du bloc polyélectrolyte à la puissance -6/23 prédite parce modèle.
HYDROPHOBICALLY MODIFIED POLYELECTROLYTES AS POTENTIAL DRUGS RESERVOIRS OF N-ALKYL-NITROIMIDAZOLES
SALAMANCA,CONSTAIN H; BARRAZA,RAúL G; ACEVEDO,BETSABé; OLEA,ANDRéS F;
Journal of the Chilean Chemical Society , 2007, DOI: 10.4067/S0717-97072007000100014
Abstract: the solubilization of three commercial drugs (ornindazole, metronidazole and tinidazole) and model compounds (n-alkyl-2-methyl-4-nitroimidazoles) on aggregates formed by anionic polyelectrolytes, carrying alkyl side chains of different length, have been investigated in aqueous solution at ph 3.0, 7.0 and 11.0. potassium salts of poly(maleic acid-co-1-olefins), pa-nk2 with n ranging from 8 to 18, were used as micelle-forming polymers. the partition of these drugs between water and the hydrophobic microdomains provided by pa-nk2 was studied by the pseudo-phase model to determinate the distribution coefficient ks, and the standard free energy of transfer δμot. the results indicate that solubility of alkyl-nitroimidazoles on these polymer micelles depends moderately on the length of the alkyl chain, and therefore is mainly determined by the heterocyclic group. on the other hand, the solubilization of 1-hexyl-2-methyl-4-nitroimidazole increase with decreasing length of the side alkyl chain; i.e. ks follows the order pa-8k2 > pa-10k2 > pa-12k2 > pa-14k2 > pa-16k2 >pa-18k2
HYDROPHOBICALLY MODIFIED POLYELECTROLYTES AS POTENTIAL DRUGS RESERVOIRS OF N-ALKYL-NITROIMIDAZOLES  [cached]
CONSTAIN H SALAMANCA,RAúL G BARRAZA,BETSABé ACEVEDO,ANDRéS F OLEA
Journal of the Chilean Chemical Society , 2007,
Abstract: The solubilization of three commercial drugs (ornindazole, metronidazole and tinidazole) and model compounds (N-alkyl-2-methyl-4-nitroimidazoles) on aggregates formed by anionic polyelectrolytes, carrying alkyl side chains of different length, have been investigated in aqueous solution at pH 3.0, 7.0 and 11.0. Potassium salts of poly(maleic acid-co-1-olefins), PA-nK2 with n ranging from 8 to 18, were used as micelle-forming polymers. The partition of these drugs between water and the hydrophobic microdomains provided by PA-nK2 was studied by the pseudo-phase model to determinate the distribution coefficient K S, and the standard free energy of transfer Δμot. The results indicate that solubility of alkyl-nitroimidazoles on these polymer micelles depends moderately on the length of the alkyl chain, and therefore is mainly determined by the heterocyclic group. On the other hand, the solubilization of 1-hexyl-2-methyl-4-nitroimidazole increase with decreasing length of the side alkyl chain; i.e. K S follows the order PA-8K2 > PA-10K2 > PA-12K2 > PA-14K2 > PA-16K2 >PA-18K2
Electrical conductivity in the early universe  [PDF]
Jarkko Ahonen,Kari Enqvist
Physics , 1996, DOI: 10.1016/0370-2693(96)00633-8
Abstract: We solve numerically the Boltzmann equation in the early universe in the presence of a constant electric field and find the electrical conductivity $\sigma$ in the range $1\MeV\lsim T\lsim M_W$. The main contribution to $\sigma$ is shown to be due to leptonic interactions. For $T\lsim 100\MeV$ we find $\sigma\simeq 0.76T$ while at $T\simeq M_W$ we obtain $\sigma\simeq 6.7T$
On the electrical conductivity of transition metals  [PDF]
T. Rajasekharan,V. Seshubai
Physics , 2011,
Abstract: We study the consequences of identifying the 'electron density parameter' N of Miedema et al. as the accurate valence of metallic elements. The incorporation of these as valence in Pauling's scheme for the electronic structure of transition metals, predicts, for the first time, that the electrical conductivity of transition metals would decrease in the order {\sigma}_Ag > {\sigma}_Cu > {\sigma}_Au > {\sigma}_Rh > {\sigma}_others, as is experimentally observed.
Morphology and electrical conductivity of PACS
GAO Bao-yu,LIU Zong-gang,YUE Qin-yan,ZHAO Hua-zhang,
GAO Bao-yu
,LIU Zong-gang,YUE Qin-yan,ZHAO Hua-zhang

环境科学学报(英文版) , 2000,
Abstract: Polyaluminium chlorides with sulfate ion(PACS) were prepared by using AlCl3· 6H2O, Al(SO4 )3· 18H2O and Na2CO3 as raw materials. The effects of basicity (r), Al3 +/SO42- molar ratio and aging time on the morphology of PACS were observed by transmission electrical microscope. The influence of aging time on charge neutralization and coagulation effect of PACS was studied.The effects of basicity (r), Al3+/SO42- molar ratio and aging time on the electrical conductivity of PACS solution were also investigated. The experimental results show that the degree of polymerization of polyaluminium chloride(PAC) increases when SO42-ion is added. The higher the basicity(r) and the longer the aging time, the larger the size of polymer PACS. The ability of PACS neutralizing the charge on Kaolinite decreases with the increase of aging time. The electrical conductivity of PACS solution (the concentration of Al3+ ion is 0.18 mol/L) with different aging time is the function of the basicity and Al3 +/SO42- molar ratios and has its maximum at r = 0.5 and Al3+/SO42- = 12.
The Electrical Conductivity in the Early Universe  [PDF]
Gordon Baym,H. Heiselberg
Physics , 1997, DOI: 10.1103/PhysRevD.56.5254
Abstract: We calculate the electrical conductivity in the early universe at temperatures below as well as above the electroweak vacuum scale, $T_c\simeq 100$GeV. Debye and dynamical screening of electric and magnetic interactions leads to a finite conductivity, $\sigma_{el}\sim T/\alpha\ln(1/\alpha)$, at temperatures well below $T_c$. At temperatures above, $W^\pm$ charge-exchange processes -- analogous to color exchange through gluons in QCD -- effectively stop left-handed charged leptons. However, right-handed leptons can carry current, resulting in $\sigma_{el}/T$ being only a factor $\sim \cos^4\theta_W$ smaller than at temperatures below $T_c$.
Research of electrical conductivity of synthetic powders  [PDF]
A. Sorek,P. Popielska-Ostrowska,M. Niesler
Archives of Materials Science and Engineering , 2012,
Abstract: Purpose: This paper describes the electrical conductivity of liquid phase powders and laboratory research of electrical conductivity of synthetic powders.Design/methodology/approach: Research of electrical conductivity of liquid synthetic slag was performed using voltmeter-ammeter method on the specially designed research stand.Findings: The electrical conductivity of slag depends on the chemical composition of the liquid slag, which is related to their ionic structure. The electrical conductivity is determined by the dimensions of the ions, their number and mobility as a function of the viscosity of the liquid in which they are.Research limitations/implications: Laboratory studies of electrical conductivity of liquid powders should be the basis for further studies crystallizer powders used in continuous casting conditions.Practical implications: The chemical composition of powders (ion) can cause changes in the lubrication conditions in the near-meniscus zone in continuous casting mold and can influence on the surface quality on the continuous casting ingots.Originality/value: This paper presents the result of research of electrical conductivity CaO-SiO2-Al2O3-FeO-MgO-K2O powders.
On the electrical conductivity of plasmas and metals  [PDF]
Basil Crowley
Physics , 2015,
Abstract: Methods for modelling the electrical conductivity of dense plasmas and liquid metals, based upon the well-known Ziman formula, are reviewed from a general perspective, and some earlier inconsistencies relating to its application to finite temperature systems are resolved. A general formula for the conductivity of a Lorentzian two-component plasma in thermal equilibrium is derived from the Lenard-Balescu collision integral in which both energy and momentum exchange between ions and electrons are accounted for. This formula is used as a basis for some generalizations of the Ziman formula, which apply to plasmas of arbitrary degeneracy over a much wider range of conditions. These formulae implicitly include the collective motions of the ions, but neglect the collective motions of the electrons. Detailed consideration of the latter shows that they generally have a small effect on the conductivity. Conditions for the validity of the Ziman formula are derived. The extension of the general theory to arbitrarily low temperatures, where the ion dynamics become dominated by collective effects, in which dynamical ion correlations need to be taken into account, is shown to lead to the well-known Bloch formula. Consideration is given to non-Lorentzian plasmas by explicitly accounting for electron-electron collisions. Corrections to the Lorentzian model in the form of a power series in 1/Z are derived.
Electrical conductivity in graphene with point defects  [PDF]
Yuriy V. Skrypnyk,Vadim M. Loktev
Physics , 2010, DOI: 10.1103/PhysRevB.82.085436
Abstract: The electrical conductivity of graphene containing point defects is studied within the binary alloy model in its dependence on the Fermi level position at the zero temperature. It is found that the minimal conductivity value does not have a universal character and corresponds to the impurity resonance energy rather than to the Dirac point position in the spectrum. The substantial asymmetry of the resulting dependence of the conductivity on the gate voltage magnitude is attributed as well to this same shift of the conductivity minimum to the resonance state energy.
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