scholarly journals Translational Dielectric Friction on a Chain of Charged Spheres

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Sondès Boughammoura ◽  
Jalel M'halla
Keyword(s):  
Large Range ◽  
Continuous Distribution ◽  
Chain Model ◽  
Conductivity Measurements ◽  
Dielectric Friction ◽  
Friction Effect ◽  
Ellipsoidal Model ◽  
A Chain ◽  
Degree Of Condensation ◽  
Charged Spheres

We have proved in details that the dielectric friction remains the principal frictional effect for a stretched polyion modeled as a chain of charged spheres, whereas, in the case of Manning’s model (infinite thread with a continuous distribution of charge), this friction effect is nonexistent. According to this chain model, it is therefore possible to detect by conductivity measurements any transition from a coiled configuration (ellipsoidal model) to a stretched configuration during dilution process. We have also underlined the important interdependence between the dielectric friction and the ionic condensation of the counterions, in order to distinguish between the Ostwald regime and the Manning regime for which the degree of condensation is practically constant in a large range of concentrations.

scholarly journals About the correlation between the mobility of a polyion and that of its counterions

2014 ◽  
Vol 10 (4) ◽  
pp. 2558-2574 ◽  
Author(s):  
Anis. GHAZOUANI ◽  
Sondes. BOUGHAMMOURA ◽  
Jalel M'HALLA
Keyword(s):  
Local Structure ◽  
Formal Analysis ◽  
Hydrodynamic Friction ◽  
Dielectric Friction ◽  
New Approach ◽  
Structure Of Water ◽  
Turn On ◽  
Counter Ions ◽  
A Chain ◽  
Charged Spheres

In this paper, we propose a new approach in order to interpret the variation of the conductibility of the PSS polyion with the nature and the concentration of the alkaline counter-ions Li+, Na+ and K+, and the hydrophobic cations Et4N+ and Bu4N+. This approach is based on a recent model in which the stretched polyion is represented by a chain of successive charged spheres, partially condensed by the counter-ions. We have found that the moderate variation of the hydrodynamic friction on the polyion with the size RM of condensed counter-ions, cannot completely explain the important decrease (of about 35% from K+ to Bu4N+) of the conductibility (lPSS,M ) of the PSS polyion with the nature of the counter-ions. Consequently, we have proposed a supplementary explanation by taking into account of the translational dielectric friction on the moving polyion. Formal analysis of this friction shows that it is very sensitive to the local structure of water surrounding the polyions. As this local structure depends in its turn, on the nature of the condensed counter-ions; we suggested that this specific sensitivity could explain the high dependence of the mobility of the polyion with the nature of its counter-ions.    

scholarly journals Studies of Electrolytic Conductivity of Some Polyelectrolyte Solutions: Importance of the Dielectric Friction Effect at High Dilution

2013 ◽  
Vol 2013 ◽  
pp. 1-15 ◽  
Author(s):  
Anis Ghazouani ◽  
Sondes Boughammoura ◽  
Jalel M'Halla
Keyword(s):  
General Description ◽  
Equivalent Conductivity ◽  
Dielectric Friction ◽  
Friction Effect ◽  
Dilute Aqueous Solutions ◽  
Polyelectrolyte Solutions ◽  
Solvent Molecules ◽  
Chain Lengths ◽  
Polystyrene Sulphonate ◽  
Charged Spheres

We present a general description of conductivity behavior of highly charged strong polyelectrolytes in dilute aqueous solutions taking into account the translational dielectric friction on the moving polyions modeled as chains of charged spheres successively bounded and surrounded by solvent molecules. A general formal limiting expression of the equivalent conductivity of these polyelectrolytes is presented in order to distinguish between two concentration regimes and to evaluate the relative interdependence between the ionic condensation effect and the dielectric friction effect, in the range of very dilute solutions for which the stretched conformation is favored. This approach is illustrated by the limiting behaviors of three polyelectrolytes (sodium heparinate, sodium chondroitin sulfate, and sodium polystyrene sulphonate) characterized by different chain lengths and by different discontinuous charge distributions.

A chain model for chromosomes

1961 ◽  
Vol 58 ◽  
pp. 1072-1077 ◽  
Author(s):  
Frank Stahl
Keyword(s):  
Chain Model ◽  
A Chain

Structure and water durability of tin(II) organosilicophosphate glasses prepared by nonaqueous acid–base reactions

2006 ◽  
Vol 21 (7) ◽  
pp. 1798-1806 ◽  
Author(s):  
Megumi Mizuno ◽  
Masahide Takahashi ◽  
Toshinobu Yoko
Keyword(s):  
Room Temperature ◽  
Orthophosphoric Acid ◽  
Chain Structure ◽  
Acid Base ◽  
Humid Atmosphere ◽  
Water Durability ◽  
Magnetic Resonance Technique ◽  
A Chain ◽  
Degree Of Condensation ◽  
High Degree

Tin(II) organosilicophosphate glasses were prepared by nonaqueous acid–base reactions using orthophosphoric acid, dimethyldichlorosilane, and tin(II)chloride as the starting materials. The structure of the methylsiloxane-phosphate copolymer (methylsilicophosphate) and tin(II) methylsilicophosphate glasses was mainly investigated by the 31P nuclear magnetic resonance technique. A chain structure composed of the –(P–O–Si–O)m– silicophosphate bonds was found as the main structural unit in the methylsilicophosphate prepared by mixing orthophosphoric acid and dimethyldichlorosilane at room temperature. Tin(II) methylsilicophosphate glasses could be prepared by introducing SnCl2 as a cross-linking agent of silicophosphate chains. By increasing the reaction temperature, it was possible to promote the reaction and then to increase the network dimensions of the resultant tin(II) methylsilicophosphate glasses. It was found that the glasses with a high degree of condensation tend to have a better water durability in a humid atmosphere.

Ab initiostudy on a chain model of theCr8molecular magnet

2008 ◽  
Vol 77 (22) ◽  
Author(s):  
D. M. Tomecka ◽  
V. Bellini ◽  
F. Troiani ◽  
F. Manghi ◽  
G. Kamieniarz ◽  
...  
Keyword(s):  
Chain Model ◽  
A Chain

scholarly journals Self-organized pattern formation increases functional diversity

2020 ◽  
Author(s):  
Janne Hülsemann ◽  
Toni Klauschies ◽  
Christian Guill
Keyword(s):  
Pattern Formation ◽  
Functional Diversity ◽  
Continuous Distribution ◽  
Stabilizing Selection ◽  
Chain Model ◽  
Self Organized ◽  
Local Functional ◽  
Spatio Temporal ◽  
Alternative Community ◽  
Food Chain Model

AbstractSelf-organized formation of spatial patterns is known from a variety of different ecosystems, yet little is known how these patterns affect functional diversity of local and regional communities. Here we use a food chain model in which autotroph diversity is described by a continuous distribution of a trait that affects both growth rate and defense against a heterotroph. On a single patch, stabilizing selection always promotes the dominance of a single autotroph species. Two alternative community states, with either defended or undefended species, are possible. In a metacommunity context, dispersal can destabilize these states, and complex spatio-temporal patterns emerge. This creates varying selection pressures on the local autotroph communities, which feed back on the trait dynamics. Local functional diversity increases ten-fold compared to a situation without self-organized pattern formation, thereby maintaining the adaptive potential of communities in an environment threatened by fragmentation and global change.

scholarly journals О декорировании зигзагообразных краев наноленты эпитаксиального графена

2019 ◽  
Vol 61 (3) ◽  
pp. 610
Author(s):  
С.Ю. Давыдов
Keyword(s):  
Density Of States ◽  
Tight Binding ◽  
Free State ◽  
Band Spectrum ◽  
Adsorption Complex ◽  
Chain Model ◽  
Double Chain ◽  
Occupation Numbers ◽  
A Chain ◽  
Analytical Expressions

AbstractA double-chain model of an epitaxial graphene nanoribbon, the zigzag edges of which are decorated with foreign adparticles, has been proposed. The substrate is assumed to be a metal. Analytical expressions for the Green’s functions of carbon adatoms and adparticles are obtained. The band spectrum for the free state is determined, and the approximation of the density of states is proposed. Analytical expressions for the occupation numbers in the mode of tight binding between the adsorption complex and the substrate are presented. A chain of carbon adatoms decorated with adparticles (epicarbyne) is considered.

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