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Tytuł:
15N magnetic relaxation study of backbone dynamics of the ribosome-associated cold shock response protein Yfia of Escherichia coli
Autorzy:
Zhukov, Igor
Bayer, Peter
Schölermann, Beate
Ejchart, Andrzej
Powiązania:
https://bibliotekanauki.pl/articles/1040866.pdf
Data publikacji:
2007
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
anisotropic overall molecular diffusion
model-free approach
15N NMR spectroscopy
stress adaptation
disordered polypetide chain motion
protein Y
Opis:
In the solution structure of the ribosome-associated cold shock response protein Yfia of Escherichia coli in the free state two structural segments can be distinguished: a well structured, rigid N-terminal part displaying a βαβββα topology and a flexible C-terminal tail comprising last 20 amino-acid residues. The backbone dynamics of Yfia protein was studied by 15N nuclear magnetic relaxation at three magnetic fields and analyzed using model-free approach. The overall diffusional tumbling of the N-terminal part is strongly anisotropic with a number of short stretches showing increased mobility either on a subnanosecond time scale, or a micro- to millisecond time scale, or both. In contrast, the unstructured polypeptide chain of the C-terminal part, which cannot be regarded as a rigid structure, shows the predominance of fast local motions over slower ones, both becoming faster closer to the C-terminus.
Źródło:
Acta Biochimica Polonica; 2007, 54, 4; 769-775
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Case Study of Diffusion of Innovation under Competition
Autorzy:
Gündüç, S.
Powiązania:
https://bibliotekanauki.pl/articles/1029620.pdf
Data publikacji:
2018-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
PACS/topics:02.30.Hq
02.60.Cb
89.65.Gh
Opis:
In this work, the aim is to discuss the relative importance of the driving parameters of the diffusion of innovation under competition. As a case study the competitive existence of Android and iOS operating systems are modeled in the context of an extended Bass model. The chosen model consists of two coupled differential equations. Each differential equation has the same form of the well known Bass equation with an extra term which represents the effect of the existence of the competitor. Since the smartphone sales and usage are globally well documented, publicly available global smartphone market share and sales data are used to determine the model parameter values. The smartphone global market share data spans 28 quarters starting from the first quarter of 2009. The distribution of the market share in the first quarter has been used as the initial values of the competing operating systems. A minimization process obtains the free parameters (six in total) of the differential equations. The values of the parameters are fixed by minimizing the difference between the solution of Bass equation and the smartphone global market share data. The parameter values of iOS and Android operating systems indicate that, on the worldwide scale, the adaptation of new ideas/products the dominantly led by the personal interactions. In fact, through social networks, information flow is immense, and individuals rely on the information obtained directly from a trusted individual. Publicity parameter values indicate that very rarely decision of an individual is formed by only the mass media or publicity. On the contrary, to the publicity parameter, it is observed that the existence of a competitor has a considerable effect on the sales of both parties.
Źródło:
Acta Physica Polonica A; 2018, 133, 6; 1465-1469
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Classical Approach to Dynamics of Parabolic Competitive Systems
Autorzy:
Pietruk, Małgorzata
Przeradzki, Bogdan
Powiązania:
https://bibliotekanauki.pl/articles/44444333.pdf
Data publikacji:
2010
Wydawca:
Uniwersytet Łódzki. Wydawnictwo Uniwersytetu Łódzkiego
Tematy:
Reaction-diffusion system
competition.
Opis:
We study the reaction-diffusion system, its stationary solutions, the behavior of the system near them and discuss similarities and differences for different boundary conditions.
Źródło:
Acta Universitatis Lodziensis. Folia Mathematica; 2010, 17; 23-38
2450-7652
Pojawia się w:
Acta Universitatis Lodziensis. Folia Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Comparative Study on the Corrosion Behaviour of Gas Nitrided and TiAlN Coated AISI D2 Steel by Thermo-Reactive Diffusion Technique
Autorzy:
Cegil, O.
Sen, U.
Sen, S.
Powiązania:
https://bibliotekanauki.pl/articles/1399731.pdf
Data publikacji:
2013-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Je
81.65.Kn
Opis:
In this study, the corrosion behaviors of nitride and titanium aluminum nitride (TiAlN) layers deposited on AISI D2 steel samples are reported. Steel was at first nitrided in a nitrogen and ammonia atmosphere at 575C for 8 h and then titanium nitride coating treatment was performed in the powder mixture consisting of ferro-titanium, aluminum, ammonium chloride and alumina at 1000C for 2 h by thermo-reactive diffusion technique. Phase analysis and corrosion tests were realized on the titanium aluminum nitride coated steel. The corrosion properties of uncoated and coated samples were characterized by potentiostatic polarization test. The tests were conducted using a three-electrode system test unit with a platinum counter electrode of $2.269 cm^2$ and an Ag/AgCl, 3 M KCl electrode as the reference electrode. Nitrided and TiAlN coated steel specimens exhibited higher corrosion resistance than uncoated steel in 0.5 M $H_2SO_4$ solution. Conclusively, the application of nitride and TiAlN films on AISI D2 steel increased surface hardness and corrosion resistance. TiAlN coating exhibits the highest corrosion resistance.
Źródło:
Acta Physica Polonica A; 2013, 123, 2; 265-267
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A comparative study on translational diffusion coefficient for some mammalian serum albumins
Porównanie współczynnika dyfuzji translacyjnej dla albumin surowicy kilku ssaków
Autorzy:
Monkos, Karol
Powiązania:
https://bibliotekanauki.pl/articles/1039603.pdf
Data publikacji:
2010
Wydawca:
Śląski Uniwersytet Medyczny w Katowicach
Tematy:
viscosity
stokes-einstein equation
serum albumin
translational diffusion coefficient
Opis:
BACKGROUND The aim of the present paper is investigation of the volume fraction dependence of the translational diffusion coefficient for some mammalian serum albumins in aqueous solutions. MATERIAL AND METHODS The viscosity of bovine, equine, ovine and rabbit serum albumin aqueous solutions was measured at temperatures ranging from 5oC to 45oC and in a wide range of concentrations. The measurements were performed with an Ubbelohde-type capillary microviscometer. RESULTS Translational diffusion coefficient at infinitely dilute solutions Do(T) can be calculated from generalized Stokes-Einstein equation if the hydrodynamic radius of albumin is known. It gives Do(T) in the range from 3.5×10-11 m2 /s (at 5oC) to 10.2 10-11 m2 /s (at 45oC) for bovine serum albumin, from 3.59×10-11 m2 /s (at 5oC) to 10.4 10-11 m2 /s (at 45oC) for equine serum albumin, from 3.42×10-11 m2 /s (at 5oC) to 9.92×10-11 m2 /s (at 45oC) for ovine serum albumin, and from 3.36×10-11 m2 /s (at 5oC) to 9.74×10-11 m2 /s (at 45oC) for rabbit serum albumin. Translational diffusion coefficient for higher concentrations D(T,φ) can be obtained from the relation: D(T,φ) = Do(T)Ηo(T)/Η(T,φ), where φ denotes volume fraction and Ηo(T) and Η(T,φ) are viscosities of water and solution, respectively, at temperature T. CONCLUSIONS The obtained results show that the translational diffusion coefficient decreases linearly with increasing volume fraction, when φ does not exceed the value of about 0.1. The dependence of the translational diffusion coefficient on volume fraction in a broader range of φ, i.e. from dilute to concentrated solutions, is nonlinear and can be described by a stretched exponential function.
WSTĘP Celem niniejszej pracy jest zbadanie zależności współczynnika dyfuzji translacyjnej od ułamka objętościowego dla albumin surowicy kilku ssaków w roztworach wodnych. MATERIAŁ I METODY Lepkość wodnych roztworów albuminy surowicy wołowej, końskiej, owczej i króliczej zmierzono w zakresie temperatur od 5oC do 45oC i w szerokim zakresie stężeń. Pomiary wykonano przy pomocy kapilarnego mikrowiskozymetru typu Ubbelohde’a. WYNIKI Współczynnik dyfuzji translacyjnej dla roztworów rozcieńczonych Do(T) można obliczyć z uogólnionego równania Stokesa-Einsteina, jeżeli znany jest promień hydrodynamiczny albuminy. Daje to Do(T) w zakresie od 3.5×10-11 m2 /s (w 5oC) do 10.2×10-11 m2 /s (w 45oC) dla albuminy surowicy wołowej, od 3.59×10-11 m2 /s (w 5oC) do 10.4×10-11 m2 /s (w 45oC) dla albuminy surowicy końskiej, od 3.42×10-11 m2 /s (w 5oC) do 9.92×10-11 m2 /s (w 45oC) dla albuminy surowicy owczej i od 3.36×10-11 m2 /s (w 5oC) do 9.74×10-11 m2 /s (w 45oC) dla albuminy surowicy króliczej. Współczynnik dyfuzji translacyjnej dla wyższych stężeń D(T,φ) można otrzymać z relacji: D(T,φ) = Do(T)Ηo(T)/Η(T,φ), w której φ oznacza ułamek objętościowy a Ηo(T) i Η(T,φ) są, odpowiednio, lepkością wody i roztworu w temperaturze T. WNIOSKI Otrzymane wyniki pokazują, że współczynnik dyfuzji translacyjnej maleje liniowo wraz ze wzrostem ułamka objętościowego, jeżeli φ nie przekracza wartości około 0.1. Zależność współczynnika dyfuzji translacyjnej od ułamka objętościowego w szerszym zakresie φ , tzn. dla roztworów od rozcieńczonych do stężonych, jest nieliniowa i można ją opisać rozciągniętą funkcją wykładniczą.
Źródło:
Annales Academiae Medicae Silesiensis; 2010, 64, 5-6; 43-53
1734-025X
Pojawia się w:
Annales Academiae Medicae Silesiensis
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A comparison of oxygen diffusion rates in sand moistened with water or PEG 20000 solution
Autorzy:
Hiller, S.
Dexter, A.R.
Powiązania:
https://bibliotekanauki.pl/articles/24419.pdf
Data publikacji:
1997
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
sand
air
oxygen diffusion
polyethylene glycol
water
Źródło:
International Agrophysics; 1997, 11, 3
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A conservative scheme with optimal error estimates for a multidimensional space-fractional Gross–Pitaevskii equation
Autorzy:
Hendy, Ahmed S.
Macías-Díaz, Jorge E.
Powiązania:
https://bibliotekanauki.pl/articles/330834.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
generalized Gross–Pitaevskii system
Riesz fractional diffusion
Sobolev inequality
conservative method
optimal error bounds
równanie Grossa-Pitaevskiego
nierówność Sobolewa
metoda konserwatywna
optymalna granica błędu
Opis:
The present work departs from an extended form of the classical multi-dimensional Gross–Pitaevskii equation, which considers fractional derivatives of the Riesz type in space, a generalized potential function and angular momentum rotation. It is well known that the classical system possesses functionals which are preserved throughout time. It is easy to check that the generalized fractional model considered in this work also possesses conserved quantities, whence the development of conservative and efficient numerical schemes is pragmatically justified. Motivated by these facts, we propose a finite-difference method based on weighted-shifted Grünwald differences to approximate the solutions of the generalized Gross–Pitaevskii system. We provide here a discrete extension of the uniform Sobolev inequality to multiple dimensions, and show that the proposed method is capable of preserving discrete forms of the mass and the energy of the model. Moreover, we establish thoroughly the stability and the convergence of the technique, and provide some illustrative simulations to show that the method is capable of preserving the total mass and the total energy of the generalized system.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2019, 29, 4; 713-723
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Diffusion Model for the Fe_{2}B Layers Formed on a Ductile Cast Iron
Autorzy:
Keddam, M.
Powiązania:
https://bibliotekanauki.pl/articles/1398194.pdf
Data publikacji:
2018-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.15.Aa
68.55.A-
68.47.De
68.55.jd
Opis:
In this work, a diffusion model was applied to estimate the boron diffusion coefficients in the $Fe_{2}B$ layers on the ASTM A-536 ductile iron in the temperature range 1173-1273 K by the powder-pack boriding. The mass balance equation at the ($Fe_{2}B$/substrate) interface was formulated considering the effect of boride incubation times. As a result, the value of activation energy for boron diffusion in the ductile iron was estimated and compared with the literature. To verify the validity of the present model, the experimental $Fe_{2}B$ layer thickness obtained at 1173 K for 10 h was compared to the predicted value. A good concordance was observed between the predicted value of $Fe_{2}B$ layer thickness and the experimental data.
Źródło:
Acta Physica Polonica A; 2018, 133, 5; 1174-1177
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Diffusion Model of Binary Systems Controlled by Chemical Potential Gradient
Autorzy:
Wróbel, Marek
Burbelko, Andriy
Powiązania:
https://bibliotekanauki.pl/articles/2105206.pdf
Data publikacji:
2022
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
diffusion
modelling
CALPHAD
chemical potential
Opis:
The paper presents a model of diffusion in a single phase with chemical potential gradient as the driving force of the process. Fick’s laws are strictly empirical and the assumption that the concentration gradients are the driving forces of diffusion is far from precise. Instead, the gradient of chemical potential μi of component i is the real driving force. The matter of governing equations of models that incorporate this approach will be raised and discussed in this article. One of more important features is the ability to acquire results where diffusion against the concentration gradient may occur. The presented model uses the Finite Difference Method (FDM) and employs the CALPHAD method to obtain chemical potentials. The calculations of chemical potential are carried out for instant conditions – temperature and composition – in the entire task domain by Thermo-Calc via a TQ-Interface. Then the heterogeneity of chemical potentials is translated into mass transfer for each individual element. Calculations of two modelling tasks for one-dimension diffusion field were carried out. First: isothermal conditions with linear initial composition distribution and second: constant temperature gradient with uniform chemical composition in the specimen. Results for two binary solid solutions: Fe-C and Fe-Si, in the FCC phase for the given tasks will be presented. Modelling allows us to estimate the time needed to reach a desired state in a particular equilibrium or quasi-equilibrium state. It also shows the path of the composition change during the process. This can be used to determine whether the system at some point is getting close to the formation of another phase due to significant deviation from its initial conditions.
Źródło:
Journal of Casting & Materials Engineering; 2022, 6, 2; 39--44
2543-9901
Pojawia się w:
Journal of Casting & Materials Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A general study of fundamental solutions in aniotropicthermoelastic media with mass diffusion and voids
Autorzy:
Chawla, Vijay
Kamboj, Deepmala
Powiązania:
https://bibliotekanauki.pl/articles/1839675.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
termosprężystość
dyfuzja masy
źródło ciepła
general solution
fundamental solution
thermoelastic
voids
mass diffusion
Opis:
The present paper deals with the study of a fundamental solution in transversely isotropic thermoelastic media with mass diffusion and voids. For this purpose, a two-dimensional general solution in transversely isotropic thermoelastic media with mass diffusion and voids is derived first. On the basis of the obtained general solution, the fundamental solution for a steady point heat source on the surface of a semi-infinite transversely isotropic thermoelastic material with mass diffusion and voids is derived by nine newly introduced harmonic functions. The components of displacement, stress, temperature distribution, mass concentration and voids are expressed in terms of elementary functions and are convenient to use. From the present investigation, some special cases of interest are also deduced and compared with the previous results obtained, which prove the correctness of the present result.
Źródło:
International Journal of Applied Mechanics and Engineering; 2020, 25, 4; 22-41
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A laboratory facility (RTD) to study radon transport through modeled soil bed: results of preliminary measurements
Autorzy:
Kozak, K.
Mazur, J.
Hovhannisyan, H.
Powiązania:
https://bibliotekanauki.pl/articles/148126.pdf
Data publikacji:
2009
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
radon
transport
facility
diffusion
Opis:
The paper describes a laboratory facility (radon transport device – RTD) which makes it possible to study radon transport. The measuring position is a vertical cylindrical vessel with a height of 202 cm and a diameter of 24 cm. It can be filled with sand, gravel or other soil materials to be studied. The facility is providing radon gas from the source to the studied material and making it possible to measure radon concentration at different vertical distances from the source. The parameters of the medium (temperature, humidity) can be measured at the same time. The preliminary measurements using the RTD with sand as medium are presented.
Źródło:
Nukleonika; 2009, 54, 3; 193-198
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Layer-by-Layer Analysis of the Corrosion Properties of Diffusion Zinc Coatings
Autorzy:
Biryukov, A.
Galin, R.
Zakharyevich, D.
Wassilkowska, A.
Kolesnikov, A.
Batmanova, T.
Powiązania:
https://bibliotekanauki.pl/articles/356101.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
diffusion zinc coatings
δ-phase
texture
simonkolleite
Opis:
To obtain anti-corrosive thermo-diffusion zinc coatings, the authors use highly effective zinc saturating mixtures. This technology makes it possible to obtain coatings with a high zinc content in the δ-phase as well as a zinc-rich phase of FeZn13 (ζ-phase) on the coating surface. As a result of long-term studies into the corrosion properties of thermo-diffusion zinc (TDZ) coatings conducted by the authors, a number of features of their corrosive behavior have been established. The corrosion rate of those coatings in desalted and chloride-containing media is lower than those of galvanic or hot-dip zinc coatings. The corrosion behavior depends on the content of zinc on the surface and the texture features of the coating. The results showed that on the surface of thermo-diffusion coatings in the corrosion on media containing chloride ions, zinc hydroxychloride (simonkolleite - Zn5Cl2[OH]8[H2O]) has been formed. Compared to coatings obtained by other methods, the rate of simonkolleite formation was higher on TDZ coatings, which might have a positive effect on their resistance in aggressive atmospheres.
Źródło:
Archives of Metallurgy and Materials; 2020, 65, 1; 99-102
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A mathematical model for file fragment diffusion and a neural predictor to manage priority queues over BitTorrent
Autorzy:
Napoli, C.
Pappalardo, G.
Tramontana, E.
Powiązania:
https://bibliotekanauki.pl/articles/331212.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
P2P model
neural network
wavelet
diffusion
file sharing
model P2P
sieć neuronowa
falka
dyfuzja
wymiana plików
Opis:
BitTorrent splits the files that are shared on a P2P network into fragments and then spreads these by giving the highest priority to the rarest fragment. We propose a mathematical model that takes into account several factors such as the peer distance, communication delays, and file fragment availability in a future period also by using a neural network module designed to model the behaviour of the peers. The ensemble comprising the proposed mathematical model and a neural network provides a solution for choosing the file fragments that have to be spread first, in order to ensure their continuous availability, taking into account that some peers will disconnect.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2016, 26, 1; 147-160
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Neumann problem for a convection-diffusion equation on the half-line
Autorzy:
Biler, Piotr
Karch, Grzegorz
Powiązania:
https://bibliotekanauki.pl/articles/1207965.pdf
Data publikacji:
2000
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Tematy:
Neumann problem
asymptotics of solutions.
convection-diffusion equation
Opis:
We study solutions to a nonlinear parabolic convection-diffusion equation on the half-line with the Neumann condition at x=0. The analysis is based on the properties of self-similar solutions to that problem.
Źródło:
Annales Polonici Mathematici; 2000, 74, 1; 79-95
0066-2216
Pojawia się w:
Annales Polonici Mathematici
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new numerical scheme for solving the two dimensional fractional diffusion equation
Autorzy:
Dilara, Altan Koç
Mustafa, Gülsu
Powiązania:
https://bibliotekanauki.pl/articles/1839848.pdf
Data publikacji:
2021
Wydawca:
Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
Tematy:
finite difference method
fractional calculus
numerical methods
metoda różnic skończonych
rachunek ułamkowy
metody numeryczne
Opis:
In this study, the locally one dimensional (LOD) method is used to solve the two dimensional time fractional diffusion equation. The fractional derivative is the Caputo fractional derivative of order α. The rate of convergence of the finite difference method is presented. It is seen that this method is in agreement with the obtained numerical solutions with acceptable central processing unit time (CPU time). Error estimates, numerical and exact results are tabulated. The graphics of errors are given.
Źródło:
Journal of Applied Mathematics and Computational Mechanics; 2021, 20, 1; 5-16
2299-9965
Pojawia się w:
Journal of Applied Mathematics and Computational Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 750

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