New possible types of relaxation kernels

Askadskii, А.A.

doi:10.1007/bf00811682

Cited by 5 publications

(8 citation statements)

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“…Similarly, the good coincidence of low molecular peak temperature with theoretical Т g was observed for all network structures synthesized in the current work. Further morphological studies and analyses of the relaxation behavior carried out using new memory functions suggested by A. Askadskii [6,7,19] demonstrated the very unusual behavior of synthesized net work structures that consist of two polymer networks with different chemical structures and rigidity of lin ear fragments. The first component consists of bulky cross linked points bound to one another by rela tively short, flexible rubber chains.…”

Section: Polymer Network With Polyether and Polydiene Linear Fragmentsmentioning

confidence: 99%

Gradient polymeric materials

et al. 2012

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Data on gradient polymeric materials that possess broadly varying mechanical, optical, and other properties are generalized. The term "gradient materials of the first type" refers to materials that possess a gradually variable elasticity modulus in the range of 3-2000 MPa for the same material that possesses no layers or interfaces, pasting, heat sealing, etc. They are produced as either transpar ent molds or composites with various reinforced fillers. The synthesis of these materials is based on the formation of polymer networks containing bulky cross linked points with short flexible fragments linking them. These networks have been computer simulated using the physical approach developed by the authors and the chosen software, which allows one to calculate polymer properties based on their chemical structure and the implementation of computerized synthesis of polymers with pre scribed properties. The term "gradient materials of the second type" refers to materials with abruptly changing elasticity modulus and transition zone between the glassy and the rubbery states. GRADIENT POLYMERIC MATERIALS 109 pound. Since the search for such a structure is one of the objectives of this method, consistent description of structures in the method of atomic constants and in CPOS must be provided. The table of atoms and the table of relatedness that sets the selection of atoms and types of bonds in the compound structure are fundamental for CPOS software. The application of this method induces the suit ability of forming these tables for every processed formula of the repeating unit. The problem of the user's communication with the software is of special interest. The image of the structure represents a planar dis position of atoms linked by definite types of bonds. If necessary, correspondence to linear Wiswesser for mulas [10] or Morgan's record form [11] is set using tables of atoms or relatedness. The problem of unique interpretation of the repeating unit structure indicated on the display is of importance. For this purpose, the presence of information about atoms, groups of atoms, and bonds in the database is monitored by the program. The program is compatible with Windows 95 or more recent versions.The Cascade program allows one to calculate more than 60 properties of polymers and copolymers. The most fundamental properties in accordance with the review are the van der Waals volume, Hildebrand solubility parameter, surface energy, refractive index at room temperature, dielectric constant at room temperature, glass transition temperature, dependence of glass transition temperature on molecular mass, temperature of onset of intensive thermal degradation, interface tension at the polymer-polymer boundary, and the elasticity modulus of rubber (rubber like plateau).The software enables one to calculate the properties of copolymers, homogeneous mixtures of poly mers, etc. The Cascade program enables the calculation of 16 characteristics for low molecular weight organic liquids. Calculation of Elasticity Modulus for Polyme...

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Section: Polymer Network With Polyether and Polydiene Linear Fragmentsmentioning

confidence: 99%

Gradient polymeric materials

et al. 2012

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“…Analysis of existing memory functions shows that, although at adequate selection of parameters they display progress of relaxation processes with sufficient accuracy, but the physical meaning of memory function parameters is not displayed. In this connection, an approach to obtain memory function, based on consideration of thermodynamic functions and their changes during relaxation process, is suggested 18, 19, 73…”

Section: Calculation Technique For Gel Relaxation Parametersmentioning

confidence: 99%

“…The main assumption suggested in the literature18, 19, 73 is that stress relaxation or creep process proceeds as a result of interaction and diffusion of kinetic units, the relaxants. The relaxants can be various groups of atoms, repeating units, larger fragments of macromolecules, and their segments.…”

Section: Calculation Technique For Gel Relaxation Parametersmentioning

confidence: 99%

“…Production of entropy (or the rate of entropy occurrence) is determined from the following expression: ( dS / dt )(1/ v ), where S is entropy, t is time, and v is the system volume. Memory functions were obtained18, 19, 73 under the assumption that the motivating force of stress relaxation is entropy production in the system (sample), which increases during stress relaxation up to a maximal value. Considering entropy of mixing of two kinds of kinetic units (relaxants and nonrelaxants) we obtain where k B is the Boltzmann constant, m * is the total amount of kinetic units (in the present case, relaxants and nonrelaxants in specific volume), and α is the part of relaxants in the total amount of kinetic units.…”

Section: Calculation Technique For Gel Relaxation Parametersmentioning

confidence: 99%

“…It is assumed73 that the memory function (in the Boltzmann–Volterra equation) is bound to entropy by reverse dependency as follows: where T *(τ) is the variable part of the memory function.…”

Section: Calculation Technique For Gel Relaxation Parametersmentioning

confidence: 99%

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Prognostic factors for survival in patients with advanced renal cell carcinoma undergoing nonmyeloablative allogeneic stem cell transplantation

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et al. 2005

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Formation of toxic amyloid structures is believed to be associated with various late‐onset neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. The fact that many proteins in addition to those that are associated with clinical conditions have the potential to form amyloid fibrils in vitro provides opportunities for studying the fundamentals of protein aggregation and amyloid formation in model systems. Accordingly, considerable interest and effort has been directed toward developing small molecules to inhibit the formation of fibrillar assemblies and their associated toxicities. In the present study, we investigated the inhibitory effect of crocin and safranal, two principal components of saffron, on fibrillation of apo‐α‐lactalbumin (a‐α‐LA), used as a model protein, under amyloidogenic conditions. In the absence of any ligand, formation of soluble oligomers became evident after 18 h of incubation, followed by subsequent appearance of mature fibrils. Upon incubation with crocin or safranal, while transition phase to monomeric beta structures was not significantly affected, formation of soluble oligomers and following fibrillar assemblies were inhibited. While both safranal and crocin had the ability to bind to hydrophobic patches provided in the intermediate structures, and thereby inhibit protein aggregation, crocin was found more effective, possibly due to its simultaneous hydrophobic and hydrophilic character. Cell viability assay indicated that crocin could diminish toxicity while safranal act in reverse order. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 854–865, 2010.

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Approximation of relaxation curves in the nonlinear region of mechanical behavior by means of new relaxation kernels

Аскадский

Valetskii

1990

Mech Compos Mater

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New possible types of relaxation kernels

Cited by 5 publications

References 1 publication

Gradient polymeric materials

Gradient polymeric materials

Prognostic factors for survival in patients with advanced renal cell carcinoma undergoing nonmyeloablative allogeneic stem cell transplantation

Approximation of relaxation curves in the nonlinear region of mechanical behavior by means of new relaxation kernels

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