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Wyświetlanie 1-15 z 19
Tytuł:
Analiza porównawcza struktury wewnętrznej implantów hydrofilowych oraz hydrofobowych stosowanych w chirurgii okulistycznej metodą spektroskopii czasów życia pozytonów
Comparative analysis of internal structures of hydrophilic and hydrophobic implants applied in ophthalmology by means of positron annihilation lifetime spectroscopy
Autorzy:
Chamerski, K.
Powiązania:
https://bibliotekanauki.pl/articles/134780.pdf
Data publikacji:
2015
Wydawca:
ADVSEO
Tematy:
soczewki wewnątrzgałkowe
anihilacja pozytonów
wolna objętość
wielozadaniowość
hydrofilowość
hydrofobowość
chromofory
intraocular lenses
positron annihilation
free volume
multivacancies
hydrophilicity
hydrophobicity
chromophores
Opis:
In presented work internal structures of intraocular lenses were analyzed in terms of defectiveness degree. Studies were conducted by means of positron annihilation lifetime spectroscopy method PALS. The aim of the work was determination of basic parameters describing annihilation centers in research materials, such as positron lifetime in bulk material, mean positron lifetime in the internal structure, positron trapping rate by trapping centers as well as free volumes dimensions. In obtained results differences in free volumes and positron traps concentrations between hydrophilic and hydrophobic materials were noted. Furthermore, comparison of materials with and without blue light chromophores revealed differences in positron trapping rate by multivacancy-like free spaces. Achieved results were referenced for mechanical properties of the studied materials.
Źródło:
Technical Issues; 2015, 3; 3-10
2392-3954
Pojawia się w:
Technical Issues
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of free volumes and light transmission in hydrogel and silicone-hydrogel polymer contact lenses
Autorzy:
Kocela, A.
Miedzinski, R.
Filipecka, K.
Filipecki, J.
Powiązania:
https://bibliotekanauki.pl/articles/173601.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
positron annihilation
UV-vis-NIR
polymers
contact lenses
free volume
Opis:
The free volume holes and light transmission of hydrogel and silicone-hydrogel polymer contact lenses were investigated. As the material, the Proclear family (omafilcon A) of hydrogel contact lenses and the Biofinity family (comfilcon A) of silicone-hydrogel contact lenses were used. Positron annihilation lifetime spectroscopy was used to characterize geometrical sizes and fractions of the free volume holes in the investigated samples. There was a clear difference in the size of free volume holes and the fractional free volume between silicone-hydrogel and hydrogel polymer contact lenses. These changes are shown by a thorough analysis of the long-lived component of lifetime of ortho-positronium. At the same time, UV-vis-NIR in the spectral range 200-1000 nm studies were performed on the same samples of contact lenses spectrometry.
Źródło:
Optica Applicata; 2016, 46, 1; 35-45
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bean cotyledons microporosity under hydration conditions
Autorzy:
Golonka, P.
Dryzek, J.
Kluza, M.
Powiązania:
https://bibliotekanauki.pl/articles/147053.pdf
Data publikacji:
2002
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
bound water
free volume
PAS
proton NMR
Opis:
Positron Annihilation Spectroscopy (PAS), proton Nuclear Magnetic Relaxation (NMR) and hydration kinetics measurements were applied to study the free volume formation process in the initial stages of bean cotyledons imbibition. These methods allowed us to analyse the behaviour of bound water in the bean cotyledon molecular structure, and to observe free volume regions formed there. They also made it possible to describe their dimensions and concentration quantitatively. Good correlation was found between the increase of the free volume radius and the amount of water bound to the bean cotyledon solid matrix.
Źródło:
Nukleonika; 2002, 47, 4; 137-140
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bending, buckling, and forced vibration analyses of nonlocal nanocomposite microplate using TSDT considering MEE properties dependent to various volume fractions of CoFe₂O₄-BaTiO₃
Autorzy:
Mohammadimehr, M.
Rostami, R.
Powiązania:
https://bibliotekanauki.pl/articles/280425.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
bending and buckling analysis
free and forced vibration analysis
nonlocal nanocomposite microplate
various volume fractions of CoFe₂O₄-BaTiO₃
Opis:
In this article, the bending, buckling, free and forced vibration behavior of a nonlocal nanocomposite microplate using the third order shear deformation theory (TSDT) is presented. The magneto-electro-elastic (MEE) properties are dependent on various volume fractions of CoFe₂O₄-BaTiO₃. According to Maxwell’s equations and Hamilton’s principle, the governing differential equations are derived. These equations are discretized by using Navier’s method for an MEE nanocomposite Reddy plate. The numerical results show the influences of elastic foundation parameters such as aspect ratio, length to thickness ratio, electric and magnetic fields and various volume fractions of CoFe₂O₄-BaTiO₃ on deflection, critical buckling load and natural frequency. The natural frequency and critical buckling load increases with the increasing volume fraction of CoFe₂O₄-BaTiO₃, also the amplitude vibration decreases with an increase in the volume fraction. This model can be used for various nanocomposite structures. Also, a series of new experiments are recommended for future work.
Źródło:
Journal of Theoretical and Applied Mechanics; 2017, 55, 3; 853-868
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Biodegradable polyester blend and copolyesters studied by positron annihilation and other methods
Autorzy:
Dębowska, M.
Rudzińska-Girulska, J.
Serwadczak, M.
Kiersnowski, A.
Pigłowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/146301.pdf
Data publikacji:
2010
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
mixing of polymers
polyesters
transesterification
positron annihilation
positronium
free volume
Opis:
Two polyesters, i.e. an aromatic one: poly(butylene terephthalate) – PBT and an aliphatic one: poly(ĺ- -caprolactone) – PCL were mixed in melt to obtain a biodegradable product. DSC, 1H NMR, SEM, WAXS, SAXS, BOD and PALS measurements were performed to study the homopolymers as well as their physical blend and copolyesters. The latter were obtained due to the transesterification reaction. Ortho-positronium (o-Ps) annihilation lifetimes were used to create the distributions of free volume. The progressive changes in probability density function of free volume, i.e. increase in large free volume holes contribution to the total free volume, appearing when going from the homopolymers to the blend and then to the copolyesters reflect the influence of: the addition of aliphatic polyester, the weight fraction of it in the composition and transesterification. The higher contribution of larger free volume holes corresponds well with the reduced crystallinity of compositions revealed in X-ray diffraction and the worsening of the regularity of structure of the macromolecules involved in formation of crystals, deduced from the 1H NMR.
Źródło:
Nukleonika; 2010, 55, 1; 57-64
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of the free volume sizes and shapes determined from crystallographic and PALS data
Autorzy:
Tydda, M.
Jasińska, B.
Powiązania:
https://bibliotekanauki.pl/articles/146378.pdf
Data publikacji:
2015
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
benzenediols
free volume
molecular crystals olanzapine
positron annihilation
positronium
positronium diffusion coefficient
Opis:
Two different classes of molecular crystals were investigated. The first group was benzenediols, which are characterized by the same chemical composition but a different organization of their crystallographic structures; all of the compounds from this group have only one kind of free volumes. The second class was represented by olanzapine, which has more complex chemical composition and two kinds of free volumes in the structure. The o-Ps lifetime values determined from positron annihilation lifetime spectroscopy (PALS) measurements agree quite well with those calculated for sizes found from crystallographic data for benzenediols (agreement within 10% of the lifetime values). For olanzapine, a good agreement is observed in the case of cuboidal free volumes, while for the other kind of void, the agreement is less satisfactory. Positronium diffusion coefficient determined from o-Ps redistribution in olanzapine agrees with these found for polymers.
Źródło:
Nukleonika; 2015, 60, No. 4, part 1; 771-775
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Free-Volume Evolution of 1-Propanol Confined in Variously Filled Regular Mesopores of SBA-15 Matrix
Autorzy:
Šauša, O.
Lukešová, M.
Švajdlenková, H.
Bartoš, J.
Powiązania:
https://bibliotekanauki.pl/articles/1033259.pdf
Data publikacji:
2017-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
positron annihilation
1-propanol
confined systems
free-volume
Opis:
The free-volume of 1-propanol (1-PrOH) confined in a regular mesoporous SBA-15 matrix was investigated by desorption experiment at room temperature and over a wide temperature range, from 15 K up to 350 K, for four different contents of 1-PrOH in the pores. The gradual desorption of 1-PrOH from the mesopores as well as the free volume temperature dependences have shown that the polar molecules of 1-PrOH located at the inner polar surface of the SBA-15 matrix are more strongly bound to the matrix surface. The subsequent discussion of the annihilation and free-volume characteristics follows.
Źródło:
Acta Physica Polonica A; 2017, 132, 5; 1572-1574
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of low temperature on the free volume in polyethylene by positron annihilation
Autorzy:
Osoba, W.
Powiązania:
https://bibliotekanauki.pl/articles/146305.pdf
Data publikacji:
2010
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
positron annihilation
polymers
free volume
Opis:
Positron lifetime measurements were performed as a function of temperature in thermo-shrunken, modified polyethylene. Mean volume of free volume cavities in the investigated polymer was estimated from the results of the measurements. This mean volume turned out to be a smooth function of temperature (from room temperature to 8.5 K). The effect of trapping of free electrons, produced during positron irradiation, was observed at lowered temperature.
Źródło:
Nukleonika; 2010, 55, 1; 69-72
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical solutions of steady free convective flow in a rectangular region with discrete wall heat and concentration sources
Autorzy:
Ambethkar, Vusala
Basumatary, Lakshmi Rani
Powiązania:
https://bibliotekanauki.pl/articles/122750.pdf
Data publikacji:
2019
Wydawca:
Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
Tematy:
control volume
discretized
temperatures
concentration
free convective flow
heat and concentration sources
heat sources
concentration sources
horizontal and vertical directions
horizontal directions
vertical directions
kontrola głośności
konwekcja swobodna
swobodny przepływ konwekcyjny
metoda objętości skończonych
źródła ciepła
źródła koncentracji
Opis:
In this paper, numerical solutions are obtained for steady free convective flow in a rectangular region with discrete wall heat and concentration sources by using the finite volume method. The governing equations consist of the continuity, momentum, energy and mass transfer. These equations conjointly with suitable boundary conditions are solved numerically by using this method. The novel concept in this work is to generalize the SIMPLE algorithm suitably and thereby compute the numerical solutions of the flow variables such as the temperature (θ) and the concentration (C) in addition to the components of velocity and the pressure. All non-dimensional parameters are chosen suitably in accordance with the physical significance of the problem under investigation. With the help of these numerical solutions, we have depicted the profiles of the velocity, pressure, temperature and concentration along the horizontal and vertical directions of the geometric centre of the region. The validity of the numerical solutions are ensured by comparing the present solutions with the benchmark solutions. Code validation has been given for the present problem.
Źródło:
Journal of Applied Mathematics and Computational Mechanics; 2019, 18, 4; 5-18
2299-9965
Pojawia się w:
Journal of Applied Mathematics and Computational Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
PALS investigation of resorcinol under high pressure
Autorzy:
Tydda, M.
Jasińska, B.
Pieniążek, A.
Powiązania:
https://bibliotekanauki.pl/articles/147999.pdf
Data publikacji:
2013
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
free volume
ortho-positronium (o-Ps)
pressure
positron annihilation lifetime spectroscopy (PALS)
Opis:
Two kinds of measurements were conducted with resorcinol at high pressure : the first one with the use of a mechanical press and the second one with the use of a gaseous compressor. In the second case, due to some gas penetrating the material structure, the lifetime spectra obtained were difficult to analyze. The free volumes in resorcinol were influenced both by high pressure and the gas coming into the crystallographic structure.
Źródło:
Nukleonika; 2013, 58, 1; 195-198
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
PALS investigations of free volumes thermal expansion of J-PET plastic scintillator synthesized in polystyrene matrix
Autorzy:
Wieczorek, A.
Zgardzińska, B.
Jasińska, B.
Gorgol, M.
Bednarski, T.
Białas, P.
Czerwiński, E.
Gajos, A.
Kamińska, D.
Kapłon, Ł.
Kochanowski, A.
Korcyl, G.
Kowalski, P.
Kozik, T.
Krzemień, W.
Kubicz, E.
Niedźwiecki, S.
Pałka, M.
Raczyński, L.
Rudy, Z.
Rundel, O.
Sharma, N. G.
Silarski, M.
Silarski, A.
Strzelecki, A.
Wiślicki, W.
Zieliński, M.
Moskal, P.
Powiązania:
https://bibliotekanauki.pl/articles/147132.pdf
Data publikacji:
2015
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
free volume
positron annihilation
polystyrene
positronium
scintillator
Opis:
The polystyrene doped with 2,5-diphenyloxazole as a primary fluor and 2-(4-styrylphenyl)benzoxazole as a wavelength shifter prepared as a plastic scintillator was investigated using positronium probe in wide range of temperatures from 123 to 423 K. Three structural transitions at 260, 283, and 370 K were found in the material. In the o-Ps intensity dependence on temperature, the significant hysteresis is observed. Heated to 370 K, the material exhibits the o-Ps intensity variations in time.
Źródło:
Nukleonika; 2015, 60, No. 4, part 1; 777-781
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Positron Annihilation Studies of the Free Volumes in Nylon12/PVA Films Treated by Supercritical Carbon Dioxide
Autorzy:
Li, Jingjing
Yin, Chongshan
Zhou, Yawei
Li, Gang
Yeh, Jen-taut
He, Chunqing
Powiązania:
https://bibliotekanauki.pl/articles/1033920.pdf
Data publikacji:
2017-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
Nylon12/PVA
ScCO₂
positron annihilation
free volume
relaxation
Opis:
Free volume variations of Nylon12/Polyvinyl alcohol (Nylon12/PVA) blends treated in supercritical carbon dioxide (ScCO₂) were investigated using positron annihilation lifetime spectroscopy. It is found that o-Ps lifetime τ₃ and the corresponding intensity I₃ in Nylon12/PVA decrease with increase of the PVA content. Being treated in ScCO₂ at 50°C and 20 MPa for 1 h, the free volume holes in Nylon12/PVA blends expand to different extents depending on the weight ratio of PVA. After releasing of CO₂, the free volume size decreases as a function of the elapsed time due to the molecular relaxation, and the relaxation time constant depends on the content of PVA in the blends.
Źródło:
Acta Physica Polonica A; 2017, 132, 5; 1552-1555
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Positrons in naphthalene : critical remarks on the relation between o-Ps lifetime and void size
Autorzy:
Goworek, T.
Zgardzińska, B.
Wawryszczuk, J.
Powiązania:
https://bibliotekanauki.pl/articles/148003.pdf
Data publikacji:
2013
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
high pressure
naphthalene
positronium quenching
free volume
Opis:
Lowering the temperature or applying high pressure leads to elimination of positronium component in the e+ lifetime spectrum in solid naphthalene. Disappearance of positronium means reaching the free volume size limit at which there is no energy level in the potential well. It allows to estimate that size, which is found inconsistent with predictions of the popular Tao-Eldrup model. The range of applicability of that model is discussed. The dependence of the free e+ decay constant on pressure indicates that positronium is formed not only in the blob processes, but during the whole free positron life. The lifetime of free positrons begins to rise with temperature earlier than Ps intensity.
Źródło:
Nukleonika; 2013, 58, 1; 183-187
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simulations of the water freezing process: numerical benchmarks
Autorzy:
Michałek, T.
Kowalewski, T. A.
Powiązania:
https://bibliotekanauki.pl/articles/1955733.pdf
Data publikacji:
2003
Wydawca:
Politechnika Gdańska
Tematy:
numerical simulation
numerical benchmarks
finite volume method
fixed grid enthalpyporosity method
volume of fluid
solidification
free surface flow
Opis:
Three numerical benchmarks concerning the freezing of water in small enclosures are analysed using the commercial FLUENT code. The first case is a steady-state natural convection in a differentially heated cavity for temperatures near the freezing point. In the second case, the freezing of water in a differentially heated cavity is simulated. The third case describes a simulation of freezing water in the presence of forced convection and a free surface flow. Two finite-differences numerical codes are used to verify results of the FLUENT simulations for the natural convection and solidification in the differentially heated cavity. It is found that the simulation of water solidification requires very fine meshes and short time steps, extending the computational time to the extreme.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2003, 7, 3; 389-408
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spoiwa o kontrolowanych zmianach objętości do prac naprawczych i uszczelniających
Cementitious materials with controlled volume changes for repairing and sealing works
Autorzy:
Nocuń-Wczelik, W.
Konik, Z.
Stok, A.
Małolepszy, J.
Powiązania:
https://bibliotekanauki.pl/articles/160884.pdf
Data publikacji:
2009
Wydawca:
Polski Związek Inżynierów i Techników Budownictwa
Tematy:
spoiwo cementowe
spoiwo bezskurczowe
spoiwo ekspansywne
zmiana objętości kontrolowana
roboty naprawcze
roboty uszczelniające
Portland cement binder
shrinkage-free binder
expansive binder
controlled volume change
repairing works
sealing works
Opis:
Sporządzono spoiwa bezskurczowe i ekspansywne złożone z cementów portlandzkich o różnym składzie oraz z tak zwanego czynnika ekspansywnego stanowiącego mieszankę cementu glinowego oraz specjalnego spieku siarczanowo-wapniowego. Określono zmiany objętości stwardniałych zaczynów, jak również dynamikę narastania wytrzymałości i czas wiązania. Ustalono doświadczalnie proporcje składników mieszanek ekspansywnych oraz receptury spoiw. Dokonano prób wyjaśnienia zmian objętości w funkcji zawartości poszczególnych składników - przeprowadzono badania składu fazowego hydratyzujących materiałów oraz obserwacje mikroskopowe.
The shrinkage-less and expansive binders were produced by mixing of different portland cements with an expansive agent composed of calcium aluminate cement and special sulfate-lime sinter. The volume changes, strength development and setting of binders were characterized. In the experiments the proportions of expansive mixtures and cementitious materials were stated. The investigations with aim to find the relationship between the volume changes and composition of initial mixtures were also carried out - the phase composition studies and microscopic observations were done.
Źródło:
Przegląd Budowlany; 2009, R. 80, nr 12, 12; 32-36
0033-2038
Pojawia się w:
Przegląd Budowlany
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 19

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