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1

Adsorption of sodium/calcium poly(acrylic acid) salts on anatase: effect of the polyelectrolyte molecular weight and neutralization

Jacquemet Christian

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 1

113--123

EN

Abstract: Interactions of poly(acrylic acid)s (PAAs) of two different molecular weights (Mw = 9,560 g×mol-1 and 4,220 g×mol-1) with surfaces of an untreated anatase TiO2 were assessed through adsorption isotherm measurements. Those dispersants were tested under different sodium-calcium neutralization states (molar ratio r = Ca2+/CO2- varying from 0 to 0.35). Their behavior towards the TiO2 surfaces can be described by the Langmuir adsorption model. For both polymers, surface coverage (Γmax) evolves linearly with the molar ratio r. For a given r value, a lower surface coverage was observed with the polymer having the highest molecular weight. The free energy of adsorption (ΔGads) of PAAs was estimated from adsorption experiment data. This calculation indicates that sorption occurs spontaneously and is unlikely to be of chemical nature. The absolute values of ΔGads are higher for the highest molecular weight polymers suggesting that they are more strongly adsorbed to anatase surfaces. The absolute values of ΔGads per mole of sodium-calcium macromolecules are found to be lower than those calculated for their homologues 100% sodium neutralized suggesting that they are bound with the solid by a fewer number of segments.

2

Correlating topology and thermodynamics to predict protein structure sensitivity to point mutations

Rodriguez P. M., Stratmann D., Duprat E., Papandreou N., Acuna R., Lacroix Z., Chomilier J.

Bio-Algorithms and Med-Systems

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2018

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Vol. 14, no. 3

art. no. 20180026

EN

The relation between distribution of hydrophobic amino acids along with protein chains and their structure is far from being completely understood. No reliable method allows ab initio prediction of the folded structure from this distribution of physicochemical properties, even when they are highly degenerated by considering only two classes: hydrophobic and polar. Establishment of long-range hydrophobic three dimension (3D) contacts is essential for the formation of the nucleus, a key process in the early steps of protein folding. Thus, a large number of 3D simulation studies were developed to challenge this issue. They are nowadays evaluated in a specific chapter of the molecular modeling competition, Critical Assessment of Protein Structure Prediction. We present here a simulation of the early steps of the folding process for 850 proteins, performed in a discrete 3D space, which results in peaks in the predicted distribution of intra-chain noncovalent contacts. The residues located at these peak positions tend to be buried in the core of the protein and are expected to correspond to critical positions in the sequence, important both for folding and structural (or similarly, energetic in the thermodynamic hypothesis) stability. The degree of stabilization or destabilization due to a point mutation at the critical positions involved in numerous contacts is estimated from the calculated folding free energy difference between mutated and native structures. The results show that these critical positions are not tolerant towards mutation. This simulation of the noncovalent contacts only needs a sequence as input, and this paper proposes a validation of the method by comparison with the prediction of stability by well-established programs.

3

Deformacionnyj mehanizm uplotneniăstrukurnogo tela

Protasenya O. N., Larchenkov L. V., Protasenya M. L., Jakubowski A.

Technical Issues

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2017

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nr 1

46--52

EN

Application of agricultural technique for preparation (loosening) of soil to sowing of agricultural cultures has an ambivalent character: from one side, elimination of weeds, and from the other mechanical destruction by the eyelids of the folded structure of soil profiles. The questions of compression of structure of soil are considered in the process of her forming and influence of the external loading without substantial violation of the structure.

4

Captivity of mean-field particle systems and the related exit problems

Tugaut J.

Probability and Mathematical Statistics

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2015

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Vol. 35, Fasc. 1

143--159

EN

A mean-field system is a weakly interacting system of N particles in Rd confined by an external potential. The aim of this work is to establish a simple result about the exit problem of mean-field systems from some domains when the number of particles goes to infinity. More precisely, we prove the existence of some subsets of RdN such that the probability of leaving these sets before any T > 0 is arbitrarily small by taking N large enough. On the one hand, we show that the number of steady states in the small-noise limit is arbitrarily large with a sufficiently large number of particles. On the other hand, using the long-time convergence of the hydrodynamical limit, we identify the steady states as N goes to infinity with the invariant probabilities of the McKean-Vlasov diffusion so that some steady states in the small-noise limit are not steady states in the large N limit.

5

Structure changes in thin metal films during their thermal treatment

Chaplanov A., Markevich M., Stelmakh V.F., Kozak C.

Przegląd Elektrotechniczny

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2010

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R. 86, nr 7

24-25

EN

Under pulsed thermal treatment of the films, grain growth takes place provided that the non-equilibrium vacancy concentration is high, thus stimulating the migration of grain boundaries.

PL

Przy poddaniu cienkich warstw obróbce termicznej impulsowej występuje rozrost ziaren pod warunkiem, że koncentracja wakansów nierównowagowych jest wysoka, stymulująca migrację granic ziaren.

6

On Relative Stability of Selected Hard Tetramer Solids

Kowalik M., Tretiakov K. V., Wojciechowski K. W.

Computational Methods in Science and Technology

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2010

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Vol. 16, No. 2

141-146

EN

The Einstein crystal method was used to determine free energy differences between some crystalline structures of hard, homonuclear tetramers. The tetramers, each built of four identical hard spheres centered on vertices of a regular tetrahedron of sides equal to the sphere diameter, were arranged in such a way that the spheres formed the fcc lattice at close packing. Various sample sizes were studied and the results were extrapolated to the thermodynamic limit. It was found that the simplest structure of the tetramers, a simple cubic lattice of molecular mass centres with all the molecules having the same orientation, shows the highest free energy amongst the studied ones. The most stable structure of the studied ones was also found.

7

An effective expansion for the free energy of quantum spin glass models with infinite-range interactions

Domański Z.

Prace Naukowe Instytutu Matematyki i Informatyki Politechniki Częstochowskiej

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2009

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Vol. 8, nr 2

37-42

EN

An expansion for the free energy functional of quantum spin models is build around diagonalisable single-ion term of the system's Hamiltonian. This expansion is obtained within the Matsubara time formalism by introducing recursive relations involving the spin correlation functions.

8

Rola termodynamiki w inżynierii materiałowej

Kędzierski Z.

Hutnik, Wiadomości Hutnicze

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2004

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Vol. 71, nr 7-8

292-297

PL

Celem publikacji jest prezentacja potencjalnych mozliwości wykorzystania termodynamiki w inżynierii materiałowej. Na przykładzie dyfuzji wstępującej omówiono rolę potencjału chemicznego jako ogólnej siły pędnej dyfuzji. Zaprezentowae zostały podstawy teorii fluktuacji i niestabilności roztworów stałych. W części końcowej opisano problemy zwiazane z energia swobodną powierzchniową i termodynamiką powierzchni międzyfazowych.

EN

The aim of the paper is outline generally usefulness of application basic thermodynamic concepts to materials science and engineering. The importance of chemical potential as general driving forceof diffusion is shortly discussed and examples of uphill diffusion are presented and explained. The role of composition flucuation in phase transformation and spinodal decomposition is also discussed. Finally fundamental problems of interface thermodynamics and effects of interface energy on phase diagram are presented.

9

Potentiometric determination of the apparent dissociation constants and free energy of transfer of tris (hydroxymethyl) aminomethane buffer in various hydroorganic media

Anwar Z. M.

Bulletin of the Polish Academy of Sciences. Chemistry

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2003

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Vol. 51, No. 3-4

195-205

EN

The apparent dissociation constant of tris (hydroxymethyl) aminomethane (Tris-buffer) was determined at (25.0 š 0.1)°C and / = 0.1 mol dm(-3) KNO3 by po-tentiometric pH titration in pure water and different hydroorganic solvent media. The organic solvents used were methanol, ethanol, N, N-dimethylformamide (DMF), acetone and dioxane. pKa(2) changes with an increase in the concentration of organic solvent. The results are discussed in terms of solvent characteristics. Solvent basicity and stabilization of the conjugate acid free base by hydrogen bonding interactions in hydroorganic solvent media relative to pure aqueous media as well as proton-solvent interaction play an important role in the dissociation equilibrium of the Tris buffer. The free energy of transfer of the protonated form of the Tris buffer to the neutral from water to mixtures of water + organic solvents are calculated.

10

Inhomogeneous superconductivity and vortices in the stripe states

Lenkowska-Czerwińska T.

Journal of Technical Physics

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2002

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Vol. 43, no 3

335-341

EN

Spatially inhomogeneous features in the spin and charge structures have been indicated in the number of experiments on high temperature materials e.g. La2-xSrxCuO4. The simple realization of this state is striped domain wall where charges form a nanoscale linear pattern in an antiferromagnetically ordered isolator. These represent a nanoscale distribution of charge and spin that is believed to be commensurably locked by the tilt distortions of the lattice. The phenomenological model of charge and spin inhomogeneities in the stripe phase of superconducting cuprates on the ground of Ginzburg-Landau theory is proposed. The corresponding free energy for the coupled charge and spin-density wave, and superconducting order parameters is constructed. The phase diagram for inhomogeneous superconducting state is discussed. The effective coherence length and the penetration depth in the London limit are introduced. The critical magnetic fields and the energy of the isolated vortex line are obtained.

11

Micro liquid-liquid extraction of acetyl derivatives of phenols

Urbanczyk A., Staniewski J., Apostoluk W., Szymanowski J.

Chemia Analityczna

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2002

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Vol. 47, No. 5

669-679

EN

Micro liquid-liquid extraction of phenols acetyl derivatives from aqueous solution was studied and distribution coefficient was successfully correlated with solvent and solute property parameters. Toluene selected as a solvent for the extraction proved to be appropriate for the process. Extraction depended mainly on the hydrophobicity of phenol acetyl derivatives and the ionic strength of the aqueous solution. With the use of large volume on-column sample introduction technique it was possible to determine phenols at the level of 1 ug L(-1) both in model and environmental samples with a flame ionization detector.

PL

Zastosowano metodę mikroekstrakcję ciecz-ciecz do wydzielania fenoli z próbek wodnych. Fenole ekstrahowano w postaci pochodnych acetylowych, przeprowadzając derywatyzację bezpośrednio w próbce wodnej za pomocą bezwodnika kwasu octowego. Wyznaczono współczynniki podziału acetylowych pochodnych fenoli pomiędzy fazę wodną i organiczną, które z powodzeniem skorelowano z parametrami rozpuszczalników oraz badanych związków. Odpowiednim ekstrahentem do tego celu okazał się toluen. Ekstrakcja zależała głównie od hydrofobowości acetylowych pochodnych fenoli oraz siły jonowej roztworu wodnego. Dozowanie próbki o dużej objętości metodą on-column pozwoliło na oznaczanie fenoli na poziomie l ug L(-1), zarówno w przypadku modelowych próbek wodnych, jak i próbek środowiskowych, przy zastosowaniu detektora płomieniowo-jonizacyjnego.

12

Błędy ułożenia - czym są i od czego zależy ich energia.

Wróbel M.

Inżynieria Materiałowa

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2001

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R. XXII, nr 6

1024-1032

PL

W pracy przedstawiono definicje błędów ułożenia (BU) i energii błędu ułożenia, rozróżniając energię hipotetycznego (nieograniczenie rozciągłego) błędu ułożenia, na który nie wpływają dyslokacje (EBU) od energii błędu ułożenia ograniczonego dyslokacjami częściowymi (efektywna energia błędu ułożenia EEBU). Przedyskutowano również ograniczenia traktowania energii błędu ułożenia jako miary względnej stabilności struktur krystalicznych. Krótko przedstawiono podstawy związku EBU z oddziaływaniami atomów i elektronów oraz przedyskutowano przyczyny wyznaczonych zależności EBU od składu chemicznego stopów i od temperatury.

EN

The concept of the stacking faults (SF), the stacking energy (SFE) and selected examples of typical SFs in the face-centered cubic (fcc) structure and in the hexagonal close-packed (hcp) structure is presented. The sequence of stacking and SFs have been described by some letters which designate position of the successive atomic planes. Additionally, Frank notation system as well as notation introduced by Jagodziński were explained and used. Some experimental SFE values for selelcted metals are collected.

13

The new way of free activation energy evaluation for cholesteryl nonanoate

Panak M.

Scientific Bulletin. Physics / Lodz University of Technology

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1998

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Vol. 18

59-68

EN

It is shown that the experimental data contradicts the theoretical Turnbull-Fisher equation G(T) if the values of free activation energy αEA and αFG calculated with traditional method are applied. The correctly calculated values of these energies are about doubled, compared to the old values. The new values assure conformity of the G(T) equation with the experiment.

PL

Energia aktywacji pelargonianu cholesterylu policzona została nową metodą. Otrzymana wartość jest dwa razy większa od wartości energii aktywacji uzyskiwanej do tej pory, ponieważ dotąd zaniedbywano wpływ energii swobodnej na proces izotermicznej krystalizacji pelargonianu cholesterylu. Nowa metoda umożliwia również wyznaczenie energii swobodnej kontrolującej proces izotermicznej krystalizacji w wyższych temperaturach.

14

Dependence of the solvation free energies on atomic charge distribution

Cieplak P.

Polish Journal of Chemistry

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1998

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Vol. 72, nr 7S

1464-1471

EN

The dependency of hydration free energies on the atomic charge distribution has been studied using the free energy perturbation method and molecular dynamics simulations. Several hypothetical sets of atomic charges for methanol molecule have been constructed, yielding the same total molecular dipole moment of 2.14 D. Each of the sets has been perturbed into another one and the electrostatic contributions to the hydration free energy differences associated with such changes have been determined. The magnitude of calculated electronic contribution to the solvation free energies crucially depends on the position of the center charge and orientation of the total dipole moment within molecular van Waals envelope. It depends less on higher molecular multipole moments. This issue of cinvergence of the electrostatic contribution to the freee energies obtained from molecular dynamics simulations will be also addressed.