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Wyszukujesz frazę "lattice models" wg kryterium: Temat


Wyświetlanie 1-7 z 7
Tytuł:
Computer simulations of protein folding with a small number of distance restraints.
Autorzy:
Sikorski, Andrzej
Kolinski, Andrzej
Skolnick, Jeffrey
Powiązania:
https://bibliotekanauki.pl/articles/1043733.pdf
Data publikacji:
2002
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
lattice models
NMR structure refinement
Monte Carlo method
reduced protein models
protein folding
Opis:
A high coordination lattice model was used to represent the protein chain. Lattice points correspond to amino-acid side groups. A complicated force field was designed in order to reproduce a protein-like behavior of the chain. Long-distance tertiary restraints were also introduced into the model. The Replica Exchange Monte Carlo method was applied to find the lowest energy states of the folded chain and to solve the problem of multiple minima. In this method, a set of replicas of the model chain was simulated independently in different temperatures with the exchanges of replicas allowed. The model chains, which consisted of up to 100 residues, were folded to structures whose root-mean-square deviation (RMSD) from their native state was between 2.5 and 5 Å. Introduction of restrain based on the positions of the backbone hydrogen atoms led to an improvement in the number of successful simulation runs. A small improvement (about 0.5 Å) was also achieved in the RMSD of the folds. The proposed method can be used for the refinement of structures determined experimentally from NMR data.
Źródło:
Acta Biochimica Polonica; 2002, 49, 3; 683-692
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Monte Carlo simulations of protein-like heteropolymers.
Autorzy:
Sikorski, Andrzej
Romiszowski, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/1044166.pdf
Data publikacji:
2001
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
lattice models
protein structure
Monte Carlo method
protein dynamics
protein folding
Opis:
Properties of a simple model of polypeptide chains were studied by the means of the Monte Carlo method. The chains were built on the (310) hybrid lattice. The residues interacted with long-range potential. There were two kinds of residues: hydrophobic and hydrophilic forming a typical helical pattern -HHPPHPP-. Short range potential was used to prefer helical conformations of the chain. It was found that at low temperatures the model chain formes dense and partially ordered structures (non-unique). The presence of the local potential led to an increase of helicity. The effect of the interplay between the two potentials was studied. After the collapse of the chain further annealing caused rearrangement of helical structures. Dynamic properties of the chain at low temperature depended strongly on the local chain ordering.
Źródło:
Acta Biochimica Polonica; 2001, 48, 1; 77-81
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Denatured proteins and early folding intermediates simulated in a reduced conformational space
Autorzy:
Kmiecik, Sebastian
Kurcinski, Mateusz
Rutkowska, Aleksandra
Gront, Dominik
Kolinski, Andrzej
Powiązania:
https://bibliotekanauki.pl/articles/1041278.pdf
Data publikacji:
2006
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
sequence profiles
statistical potentials
protein folding intermediates
high resolution lattice protein models
Replica Exchange Monte Carlo
molten globule
protein folding
Opis:
Conformations of globular proteins in the denatured state were studied using a high-resolution lattice model of proteins and Monte Carlo dynamics. The model assumes a united-atom and high-coordination lattice representation of the polypeptide conformational space. The force field of the model mimics the short-range protein-like conformational stiffness, hydrophobic interactions of the side chains and the main-chain hydrogen bonds. Two types of approximations for the short-range interactions were compared: simple statistical potentials and knowledge-based protein-specific potentials derived from the sequence-structure compatibility of short fragments of protein chains. Model proteins in the denatured state are relatively compact, although the majority of the sampled conformations are globally different from the native fold. At the same time short protein fragments are mostly native-like. Thus, the denatured state of the model proteins has several features of the molten globule state observed experimentally. Statistical potentials induce native-like conformational propensities in the denatured state, especially for the fragments located in the core of folded proteins. Knowledge-based protein-specific potentials increase only slightly the level of similarity to the native conformations, in spite of their qualitatively higher specificity in the native structures. For a few cases, where fairly accurate experimental data exist, the simulation results are in semiquantitative agreement with the physical picture revealed by the experiments. This shows that the model studied in this work could be used efficiently in computational studies of protein dynamics in the denatured state, and consequently for studies of protein folding pathways, i.e. not only for the modeling of folded structures, as it was shown in previous studies. The results of the present studies also provide a new insight into the explanation of the Levinthal's paradox.
Źródło:
Acta Biochimica Polonica; 2006, 53, 1; 131-144
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A contribution to dynamics of polyatomic lattices
Autorzy:
Rychlewska, J.
Szymczyk, J.
Woźniak, C.
Powiązania:
https://bibliotekanauki.pl/articles/279686.pdf
Data publikacji:
1999
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
lattice dynamics
continuum models
Opis:
Using a concept of internal degrees of freedom a new finite difference formulation of polyatomic lattice dynamics is proposed. A transition from the nonlocal equations of motion to the partly local and local ones as well as the possibility of reduction of internal degrees of freedom are shown.
Wprowadzając pojęcie wewnętrznych stopni swobody sformułowano nową różnicową postać dynamiki sieci złożonych. Pokazano przejście od równań nielokalnych do modeli częściowo i całkowicie lokalnych oraz zwrócono uwagę na możliwość wyrugowania wewnętrznych stopni swobody.
Źródło:
Journal of Theoretical and Applied Mechanics; 1999, 4; 799-807
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lattice rotation definition and predicted textures of tensile and compression deformation
Autorzy:
Wroński, M.
Wierzbanowski, K.
Powiązania:
https://bibliotekanauki.pl/articles/352559.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
axisymmetric deformation
texture
lattice rotation
deformation models
Opis:
The problem of ambiguity in the definition of lattice rotation, used in plastic deformation models, is examined in this work. The geometry of tensile and compression deformation is considered. Two approaches to lattice rotation are considered: the classical definition (called also 'mathematical analysis) and the definition based on orientation preservation of specified directions/planes in the sample coordinates system. Similar study was already done by the present authors for the geometry of rolling deformation. It was shown that application of two rotation definitions enables to explain the appearance of two types of f. c. c. rolling textures: brass type and copper type textures. In the case of axisymmetric deformation the application of both definitions of lattice rotation leads to similar textures, but with different spread of their principal components.
Źródło:
Archives of Metallurgy and Materials; 2016, 61, 3; 1529-1536
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Problem of lattice rotation due to plastic deformation. Example of rolling of f.c.c materials
Problem obrotu sieci krystalicznej podczas odkształcenia plastycznego. Przykład walcowania materiałów o sieci regularnej płasko centrowanej
Autorzy:
Wierzbanowski, K.
Wroński, M.
Baczmański, A.
Bacroix, B.
Lipiński, P.
Lodini, A.
Powiązania:
https://bibliotekanauki.pl/articles/351483.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
obrót sieci
sprężysto-plastyczny model odkształcenia
tekstura
walcowanie
lattice rotation
elasto-plastic deformation models
copper-brass texture transition
rolling deformation
Opis:
Rotations of grain crystal lattice are responsible for texture formation during plastic deformation. The classical definition of lattice rotation leads in some cases to different texture predictions than the definition based on the orientation preservation of selected sample directions and/or planes. For example, if classical <110>{111} slip is taken into account for f.c.c. materials, the former approach enables to predict both copper and brass types of rolling texture, while classical approach predicts only the first one. The analysis of rolling process was done for two types of lattice rotation and in function of grain-matrix interaction parameter used in a deformation model. Correlation factors estimating the similarity of predicted and experimental textures as well as the shares of ideal orientations are discussed.
Obroty sieci krystalograficznej ziaren są odpowiedzialne za powstania tekstury podczas odkształcenia plastycznego. Klasyczna definicja obrotu sieci prowadzi w pewnych przypadkach do innych przewidywań tekstury niż definicja oparta na warunku zachowania wybranych kierunków lub płaszczyzn próbki. Na przykład biorąc pod uwagę systemy poślizgu <110>{111}, użycie tej drugiej pozwala przewidzieć zarówno teksturę typu miedzi jak i mosiądzu, podczas gdy definicja klasyczna umożliwia przewidywanie jedynie tekstury typu miedzi. Dokonano analizy odkształcenia przez walcowanie dla obu definicji obrotu uwzględniając równocześnie wpływ parametru oddziaływania ziarna z otaczającym materiałem. W celu porównania przewidzianych i zmierzonych tekstur wyliczono i przedyskutowano współczynniki korelacji oraz udziały orientacji idealnych.
Źródło:
Archives of Metallurgy and Materials; 2011, 56, 3; 575-584
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Topology and models of ZFC at early Universe
Autorzy:
Król, Jerzy
Asselmeyer-Maluga, Torsten
Powiązania:
https://bibliotekanauki.pl/articles/690832.pdf
Data publikacji:
2019
Wydawca:
Copernicus Center Press
Tematy:
Cosmological model
exotic R4 and S3 × R in cosmology
4-exotic smoothness
models of ZFC
topological model for inflation
topological model for neutrino masses
forcing
QM lattice of projections
Opis:
Recently the cosmological evolution of the universe has been considered where 3-dimensional spatial topology undergone drastic changes. The process can explain, among others, the observed smallness of the neutrino masses and the speed of inflation. However, the entire evolution is perfectly smooth from 4-dimensional point of view. Thus the raison d’être for such topology changes is the existence of certain non-standard 4-smoothness on R4 already at very early stages of the universe. We show that the existence of such smoothness can be understood as a byproduct of the quantumness of the origins of the universe. Our analysis is based on certain formal aspects of the quantum mechanical lattice of projections of infinite dimensional Hilbert spaces where formalization reaches the level of models of axiomatic set theory.
Źródło:
Zagadnienia Filozoficzne w Nauce; 2019, 66; 15-33
0867-8286
2451-0602
Pojawia się w:
Zagadnienia Filozoficzne w Nauce
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-7 z 7

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