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Wyświetlanie 1-15 z 750
Tytuł:
Statistical properties of a polymer chain in the environment with low concentration of nanoparticles
Autorzy:
A. Tsehay, Dessalegne
Luo, Meng-Bo
Powiązania:
https://bibliotekanauki.pl/articles/1050809.pdf
Data publikacji:
2018-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
diffusion
conformation
polymer chain
nanoparticles
molecular dynamics
Opis:
We have investigated the statistical properties of polymer in the environment with low concentration of nanoparticles by using large-scale molecular dynamics simulations. The scaling law for the mean square radius of gyration was examined and simulation results for the polymer lengths 64≤N≤144 yielding a reasonably accurate value of the Flory exponent ν=0.58 at weak polymer-nanoparticle interaction ε_{PN}. Within the same range of N, the mean asphericity of the chain is independent of N. We found that the polymer behaves like a self-avoiding walk chain at small ε_{PN} and a compact sphere at large ε_{PN}. The results are attributed to the increase in the contact between polymer and nanoparticles with increasing ε_{PN}. Normal diffusions of polymer are always observed at whatever ε_{PN} and size and concentration of nanoparticles. Our result shows that the normal diffusion behavior of polymer is independent of polymer's state even though there is a phase transition from a desorbed polymer phase at small ε_{PN} to an adsorbed polymer phase at large ε_{PN}.
Źródło:
Acta Physica Polonica A; 2018, 133, 5; 1274-1280
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Electrochemical Study of the Corrosion Resistance of Niobium-Aluminum Carbonitride Coating Produced on Steels by Thermo-Reactive Diffusion Technique
Autorzy:
Abakay, E.
Durmaz, M.
Sen, S.
Sen, U.
Powiązania:
https://bibliotekanauki.pl/articles/1031643.pdf
Data publikacji:
2017-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.65.Lp
81.65.Kn
87.64.Ee
Opis:
Thermo-reactive diffusion/deposition technique is an alternative to physical vapor deposition and chemical vapor deposition techniques for obtaining wear and corrosion resistant coatings on steel parts. In this work, thermo-reactive diffusion/deposition technique was used to produce niobium aluminum carbonitride-based coatings on AISI M2 steel. Characterization of the coatings was done by X-ray diffraction analysis, scanning electron microscopy and energy dispersive spectroscopy. The corrosion resistance of the produced coatings was investigated by using potentiodynamic polarization in a solution of 0.5 M NaCl. Hard, compact and adherent coatings, mainly consisting of NbC and NbN phases were obtained. The corrosion behavior of the samples was investigation by potentiodynamic polarization measurements.
Źródło:
Acta Physica Polonica A; 2017, 132, 3; 682-684
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
FORMULATION AND EVALUATION OF INDOMETHACIN LOADED NANOSPONGES FOR ORAL DELIVERY
Autorzy:
Abbas, Nasir
Sarwar, Komal
Irfan, Muhammad
Hussain, Amjad
Mehmood, Rabia
Arshad, Muhammad S.
Shah, Pervaiz A.
Powiązania:
https://bibliotekanauki.pl/articles/895238.pdf
Data publikacji:
2018-10-31
Wydawca:
Polskie Towarzystwo Farmaceutyczne
Tematy:
sustained release
indomethacin
Nanosponges
Emulsion solvent diffusion method
Franz diffusion cell
Opis:
Nanosponges (NS) loaded sustained release tablet formulations of a non-steroidal anti-inflammatory drug; Indomethacin were successfully developed and evaluated for their pharmaceutical properties. Twelve nanosponge formulations were fabricated by solvent diffusion method by using different ratios of drug and polymers (ethyl cellulose and polyvinyl alcohol). Particle size of all the formulations was in the nano range of 221 to 625 nm and it was found dependent on the polymer concentration. Drug loading and entrapment efficiency was ranged in 32.2 to 59.4 % and 30.1 to 64.8 %, respectively. Formulations with equal proportion of drug and polymer resulted in higher values of drug loading and entrapment efficiency. Percent yield was also found dependent on the relative drug polymer ratio with highest value of 51 % was achieved for the formulation having same drug to polymer ratio. SEM results confirmed the formation of spherical and porous structures. Structural analysis by Fourier transform infrared spectroscopy (FTIR), powder x-ray diffraction (PXRD) showed the absence of any interaction between drug and polymer. In comparison to pure drug, NS formulations showed a linear intrinsic dissolution rate (IDR) profile depicting a controlled release profile. Diffusion studies of NS formulations performed by Franz diffusion cell and dialysis bag methods showed comparable results in terms of precision and linearity of diffusion profile. Tablets prepared from the drug loaded NS showed acceptable values for hardness, friability and drug content. Release of drug from NS tablets was confirmed as sustained release behaviour.
Źródło:
Acta Poloniae Pharmaceutica - Drug Research; 2018, 75, 5; 1201-1213
0001-6837
2353-5288
Pojawia się w:
Acta Poloniae Pharmaceutica - Drug Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling of distributed parameter nonlinear systems by differential Taylor method
Autorzy:
Abbasov, T.
Herdem, S.
Koeksal, M.
Powiązania:
https://bibliotekanauki.pl/articles/206479.pdf
Data publikacji:
1999
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
filtracja
równania różniczkowe zwyczajne
sterowanie
systemy nieliniowe
absorption
convective diffusion
differential Taylor transform
distributed parameter systems
ecological systems
engineering systems
Opis:
Modelling, solution, control and even design of many ecological and engineering systems involve dealing with nonlinear partial differential equations of which analytic solutions are rarely available and numerical approach with or without linearization, or approximation is inevitable most of the time. In this paper the possibility of analysing such systems by using a fairly new method known as Differential Taylor (DT) Transform and its advantages are proved. The results obtained by this method are compared with the experimental results and shown to be within good agreement with them. It is emphasised that DT Transform is not effective for only filtration systems, but can also be used equally well for absorption, heat and mass transfer, convective diffusion and similar systems.
Źródło:
Control and Cybernetics; 1999, 28, 2; 259-267
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Adsorption mechanism and modelling of hydrocarbon contaminants onto rice straw activated carbons
Autorzy:
Abdel daiem, Mahmoud M.
Sánchez-Polo, Manuel
Rashed, Ahmed S.
Kamal, Nehal
Said, Noha
Powiązania:
https://bibliotekanauki.pl/articles/779863.pdf
Data publikacji:
2019
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
activated carbon
rice straw
adsorption mechanism
adsorption modeling
pore volume surface diffusion
Opis:
The adsorption of Diphenolic acid (DPA), 2,4-Dichlorophenoxyacetic acid (2,4-D), and 2-methyl-4-chlorophenoxyacetic acid (MCPA) were examined in aqueous solution using activated carbon rice straw. The rice straw was activated by using two reagents, zinc chloride and phosphoric acid and named as RSZ, RSP, respectively. The results showed that both carbons have a relatively high adsorption capacity. Concerning the adsorption kinetic, the second-order model has better fit than the first model to experimental data. The adsorption yield of both carbons increased in the order: DPA < 2,4-D < MCPA. The pore volume diffusion model satisfactorily fitted the experiment on both carbons. Furthermore, solution pH has a high influence on the adsorption capacity for both carbons. The adsorption mechanism of selected pollutants onto carbon samples has been controlled by dispersion interaction π-π electrons and electrostatic interaction, moreover, the contribution of pore volume diffusion is the controlling mechanism of the overall rate of adsorption.
Źródło:
Polish Journal of Chemical Technology; 2019, 21, 4; 1-12
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some examples of solutions to an inverse problem for the first-passage place of a jump-diffusion process
Autorzy:
Abundo, Mario
Powiązania:
https://bibliotekanauki.pl/articles/2183487.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
jump-diffusion process
first-passage place
inverse first-passage place problem
Opis:
We report some additional examples of explicit solu- tions to an inverse first-passage place problem for one-dimensional diffusions with jumps, introduced in a previous paper. If X(t) is a one-dimensional diffusion with jumps, starting from a random position η 2 [a, b], let be τa,b the time at which X(t) first exits the interval (a, b), and πa = P(X(τa,b) ≤ a) the probability of exit from the left of (a, b). Given a probability q 2 (0, 1), the problem consists in finding the density g of η (if it exists) such that πa = q; it can be seen as a problem of optimization.
Źródło:
Control and Cybernetics; 2022, 51, 1; 31--42
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The innovation diffusion theory in studies on contacts of the Australian communities of Polish origin with Poland
Autorzy:
Achmatowicz-Otok, Anna
Powiązania:
https://bibliotekanauki.pl/articles/1964022.pdf
Data publikacji:
1986-06-01
Wydawca:
Uniwersytet Warszawski. Wydział Geografii i Studiów Regionalnych
Źródło:
Miscellanea Geographica. Regional Studies on Development; 1986, 2; 249-254
0867-6046
2084-6118
Pojawia się w:
Miscellanea Geographica. Regional Studies on Development
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the structure of the diffusion distance induced by the fractional dyadic Laplacian
Autorzy:
Acosta, María Florencia
Aimar, Hugo
Gómez, Ivana
Morana, Federico
Powiązania:
https://bibliotekanauki.pl/articles/29519486.pdf
Data publikacji:
2024
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
diffusion metrics
dyadic diffusion
Opis:
In this note we explore the structure of the diffusion metric of Coifman-Lafon determined by fractional dyadic Laplacians. The main result is that, for each t > 0, the diffusion metric is a function of the dyadic distance, given in $ \mathbb{R}^+ $ by δ(x, y) = inf {|I| : I is a dyadic interval containing x and y}. Even if these functions of δ are not equivalent to δ, the families of balls are the same, to wit, the dyadic intervals.
Źródło:
Opuscula Mathematica; 2024, 44, 2; 157-165
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Badanie transportu składnika w układach symulujących układy biomedyczne
Component mass transfer in systems simulating biomedical systems
Autorzy:
Adach, A.
Pawlak, A.
Zera, A.
Kaczorowska, B.
Kamińska, D.
Powiązania:
https://bibliotekanauki.pl/articles/2072081.pdf
Data publikacji:
2014
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
dyfuzja
transport leków
transport substancji
komora dyfuzyjna
diffusion
drug release
substance transfer
diffusion chamber
Opis:
Podstawowym mechanizmem transportu masy w układach biomedycznych jest dyfuzja w ciałach porowatych lub cieczy, transport przez błony selektywne. W pracy doświadczalnie zbadano szybkość transportu składnika wykorzystując skonstruowany zestaw sekwencyjny, będący modyfikacją komory dyfuzyjnej i metody warstwy półnieskończonej. Substancją aktywną była czerwień koszenilowa A. Stosowano takie media jak: hydrożele, syntetyczna ślina, roztwór cieczy lepkiej imituj ący śluz (roztwory soli sodowej karboksymetylocelulozy). Jako podkładki wykorzystywano membrany Pałł Supor 100 Membrane Filters PES (0,1 μm). Wyznaczono gęstości strumienia składnika, współczynniki filtracji oraz wartości zastępczego współczynnika dyfuzji.
The basic mechanism of mass transfer in biomedical systems is diffusion in porous bodies or liquids and transport by selective membranes. An originally designed system with the sequential unit as a main element, being the modification of diffusion chamber, was constructed. An active substance applied was Cochineal Red A, whereas hydrogels, synthetic saliva and solution of viscous liquid imitating mucus (solutions of sodium carboxyme-thyl cellulose) were used as media. Pall Supor 100 Membrane Filters PES (0.1 μm) were employed as rootstocks. The drug flux, permeation coefficient and effective diffusion coefficients were calculated. Keywords: diffusion, drug release, substance transfer, diffusion chamber
Źródło:
Inżynieria i Aparatura Chemiczna; 2014, 1; 8--9
0368-0827
Pojawia się w:
Inżynieria i Aparatura Chemiczna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of diffusion coefficient and permeability through the barrier of substance in simulated biomedical systems
Autorzy:
Adach, A.
Skassa, A.
Bugalska, A.
Kister, N.
Powiązania:
https://bibliotekanauki.pl/articles/952660.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
drug release
substance transfer
diffusion chamber
biomedical systems
uwalnianie leku
transfer substancji
komora dyfuzyjna
systemy biomedyczne
Opis:
The investigations deal with mass transfer in simulated biomedical systems. The modification of classical diffusion chamber, sequential unit (SU) system, imitated different biomedical setups, boundary conditions. The experiments simulated: diffusion chamber (also with two barriers), transport through the membrane to the blood stream, transport from the stent eluting drug simultaneously to the vessel cells and to the blood stream. The concentrations of substances and the relative mass increases/decreases for SU systems indicate that the order of the curves follows the order of mass transfer resistances. The strong dependence of mass transfer rates versus type of diffusing substance was confirmed. The calculated drug fluxes, diffusion coefficients, permeation coefficients are convergent with literature. Permeation coefficients for complex sequential systems can be estimated as parallel connexion of constituent coefficients. Experiments approved functionality of the SU for investigations in a simulated biomedical system. Obtained data were used for numerical verification.
Źródło:
Chemical and Process Engineering; 2017, 38, 4; 543-554
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Triple diffusive convection of a non-Newtonian fluid under the combined effect of compressibility and variable gravity
Autorzy:
Aggarwal, A. K.
Dixit, D.
Powiązania:
https://bibliotekanauki.pl/articles/265482.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
dyfuzja
płyn Rivlina-Ericksena
ściśliwość
zmienna grawitacja
triple diffusion
Rivlin-Ericksen fluid
suspended particles
porous medium
compressibility
variable gravity
Opis:
In this paper, triple diffusive convection in a Rivlin-Ericksen fluid layer, which is permeated with suspended particles in the porous medium under the effect of compressibility and variable gravity, is investigated. Linear stability theory and normal mode analysis have been used to study the problem under consideration. It is observed that, for stationary convection, suspended particles, compressibility and medium permeability have destabilizing/stabilizing effects under certain conditions. The variable gravity parameter destabilizes the system whereas stable solute gradients have a stabilizing effect.
Źródło:
International Journal of Applied Mechanics and Engineering; 2019, 24, 4; 1-11
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Molybdenum Disulfide (MoS2) Coating on AISI 316 Stainless Steel by Thermodiffusion Method
Autorzy:
Akbarzadeh, M.
Zandrahimi, M.
Moradpour, E.
Powiązania:
https://bibliotekanauki.pl/articles/351550.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
thermo-diffusion method
solid lubricant coating
molybdenum disulfide
Opis:
Molybdenum disulfide (MoS2) is one of the most widely used solid lubricants applied in different ways on the surfaces under friction. In this work, AISI 316 austenitic stainless steel was coated with MoS2, using thermo-diffusion method at different temperatures and times. Coatings properties were investigated using SEM, EDX, XRD and FTIR, Hardness Tester and Roughness tester. The results illustrated the formation of a uniform layer on the surface, containing MoS2 and MoO3–X phases. The thickness, grain size and the hardness of the coatings were 20-50 μm, 400-1000 nm and 350- 550 HV respectively. Friction tests carried out using ball-on-disc method under normal loads of 10 N under ambient conditions showed values of the friction coefficient 0.30-0.40. In addition, the kinetics of diffusion layers between the substrate and the coating were also investigated. It was found that there at steady temperature there is a parabolic relationship between the thickness of the diffusion layer and the treatment time. The activation energy for the process was estimated to be 143 kJ mol-1. Depending on the treatment time and temperature, the thicknesses of diffusion layer varied between 0.5 and 2.5 microns.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 3; 1741-1748
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ensemble Averages Calculated for Two-Dimensional Smoluchowski-Debye Rotational Diffusion in DC Electric Field
Autorzy:
Alexiewicz, W.
Kielich, S.
Wołejko, L.
Powiązania:
https://bibliotekanauki.pl/articles/1931352.pdf
Data publikacji:
1994-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
77.40.+i
Opis:
Ensemble averages ⟨cos nϑ(t)⟩ (n = 1, 2, 3, 4) are calculated for the two-dimensional Smoluchowski-Debye rotational diffusion model in the presence of a DC reorienting electric field. The time dependence of ⟨cos nϑ(t)⟩ is plotted for the special cases of (i) dipolar nonpolarizable molecules (p ≠ 0), and (ii) nondipolar anisotropically polarizable molecules (p = 0) and rectangular reorienting pulses.
Źródło:
Acta Physica Polonica A; 1994, 85, 6; 959-969
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pollution in Shatt Al-Arab River near Hospital Wastewater Disposal – Detection of Pharmaceutical Compounds, Isolation and Identification of Drug-Resistant Bacteria
Autorzy:
Alsaad, Noor Kadhim
Almansoory, Asia Fadhile
Al-Baldawi, Israa Abdulwahab
Powiązania:
https://bibliotekanauki.pl/articles/2202283.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
resistant bacteria
well diffusion
river
pharmaceutical
micropollutants
Opis:
Pharmaceutical compounds have been introduced into the aquatic ecosystems in multiple ways and sources, which negatively affects the health of the environment and humans. The river near the hospital sewage disposal is host environment for drug-resistant bacteria (DRB). In this context, the aim of the research was to detect the presence of pharmaceuticals in hospital wastewater, after treatment, at river point followed by isolation of bacteria and test for resistant pharmaceutical compound. Fifteen species of bacteria isolated by angiogenic methods were identified and tested using the well diffusion test to determine the resistance of selected bacteria to ibuprofen by survival assessment. This study showed that the ibuprofen detected by GC-mass was available in all selected points at a concentration of 3 to 120 mg/L. Lecuco. mesen.cremris and Koc.rosea have a high ability to break down the ibuprofen compound. Thus, the bacteria isolated from hospital wastewater can biologically degrade ibuprofen.
Źródło:
Journal of Ecological Engineering; 2022, 23, 12; 29--36
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Specification of the process of chloride extraction from reinforced concrete based on the inverse task of the diffusion equation
Autorzy:
Alsabry, A.
Zybura, A.
Powiązania:
https://bibliotekanauki.pl/articles/265298.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
korozja
dyfuzja
ekstrakcja
corrosion
diffusion
inverse task
removing chlorides
extraction
Opis:
When the structure of reinforcement is in danger of chloride corrosion it is possible to prevent this disadvantageous phenomenon through exposing the cover to the influence of an electric field. The forces of an electric field considerably reduce chloride ions in pore liquid in concrete, which helps to rebuild a passive layer on the surface of the reinforcement and stops corrosion. The process of removing chlorides can be described with multi-component diffusion equations. However, an essential parameter of these equations, the diffusion coefficient, can be determined on the basis of an inverse task. Since the solution was achieved for one-dimension flow, the method applied can be confirmed by experimental results and the material parameters of the process can be determined theoretically. Some examples of numerical calculations of the effective electro-diffusion coefficient of chloride ions confirmed the usefulness of the theoretical solution for generalizing experimental results. Moreover, the calculation process of the numerical example provides some practical clues for future experimental research, which could be carried out in close connection with the theoretical solution.
Źródło:
International Journal of Applied Mechanics and Engineering; 2016, 21, 2; 261-271
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 750

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