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Tytuł:
Structure and Properties of Metals
Autorzy:
Kurzydłowski, K. J.
Powiązania:
https://bibliotekanauki.pl/articles/2010997.pdf
Data publikacji:
1999-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
62.20.-x
62.20.Fe
Opis:
Metals are one of the most widely used types of engineering materials. Some of their properties, e.g. elastic constants, can be directly related to the nature of the metallic bonds between the atoms. On the other hand, macro- and microstructural features of metals, such as point defects, dislocations, grain boundaries, and second phase particles, control their yield, flow, and fracture stress. Images of microstructural elements can be obtained by modern imaging techniques. Modern computer aided methods can be further used to obtain a quantitative description of these microstructures. These methods take advantage of the progress made in recent years in the field of image processing, mathematical morphology and quantitative stereology. Quantitative description of the microstructures are used for modeling processes taking place under the action of applied load at a given temperature and test (service) environment. These model considerations can be illustrated on the example of an austenitic stainless steel, which is an important material for power generating and chemical industry. Reports recently published also show that properties of materials can be significantly modified by the effect of free surface. Examples of such situations include environmental effect on the mechanical properties of materials. Data for an austenitic stainless steel is used to discuss contribution of the free surface to the mechanical properties of metals.
Źródło:
Acta Physica Polonica A; 1999, 96, 1; 69-79
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nuclear Magnetic Relaxation Dispersion Study of Human Serum Proteins Solutions
Autorzy:
Olszewski, K. J.
Powiązania:
https://bibliotekanauki.pl/articles/1920946.pdf
Data publikacji:
1992-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.90.+d
87.45.-k
Opis:
Nuclear magnetic relaxation dispersion profiles in the Larmor frequency range of 0.02-50 MHz and 277 K has been studied for human serum proteins: albumin, γ-globulins and α, β-globulins in aqueous solutions 3-14 per cent by weight of protein. The linear concentration dependences have been found both for the longitudal relaxation rates for water protons and the dispersive and non-dispersive parts of relaxation profiles. The frequency dependent relaxivities have been calculated, the hydrodynamic effect for the albumin macromolecule Brownian rotational correlation time has been observed and analyzed. The importance of molecular weight of protein for the relaxation processes and its influence for magnetic resonance imaging contrast was discussed.
Źródło:
Acta Physica Polonica A; 1992, 82, 3; 487-494
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spectroscopy of Be Acceptor Ground State in GaAs/AlGaAs Heterostructure
Autorzy:
Łusakowski, J.
Buczko, R.
Sakowicz, M.
Friedland, K. J.
Hey, R.
Ploog, K.
Powiązania:
https://bibliotekanauki.pl/articles/2047378.pdf
Data publikacji:
2007-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.70.Ej
78.67.De
Opis:
Photoluminescence measurements were carried out on Be δ-doped GaAs/Al$\text{}_{0.33}$Ga$\text{}_{0.67}$As heterostructure at 1.6 K in magnetic fields (B) up to 4 T. Luminescence originating from recombination of a two-dimensional electron gas and photoexcited holes localized on Be acceptors was analyzed. The degree of circular polarization (γ$\text{}_{C}$) of the luminescence from fully occupied Landau levels was determined as a function of B and the two-dimensional electron gas concentration, n$\text{}_{s}$. At B constant,γ$\text{}_{C}$ decreased with the increase in n$\text{}_{s}$. The intensity of the optical transition considered was calculated with taking into account s- and d-like parts of the acceptor envelope function. It is shown that the presence of the d-like part explains the observed γ$\text{}_{C}$(n$\text{}_{s}$) dependence quantitatively. This shows that polarization spectroscopy on acceptorδ-doped heterostructures enables one to test experimentally the contribution of the L>0 component of the envelope in a shallow acceptor description.
Źródło:
Acta Physica Polonica A; 2007, 112, 2; 209-213
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Photoemission Study of the Initial Growth of Co on Ru(0001)
Autorzy:
Godowski, P. J.
Onsgaard, J. J.
Trzebiatowska-Gusowska, M. J.
Pater, K. J.
Li, Zhe
Powiązania:
https://bibliotekanauki.pl/articles/2047268.pdf
Data publikacji:
2007-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
79.60.Dp
79.60.Jv
68.55.Jk
Opis:
The growth process of cobalt on Ru(0001) was characterized by photoelectron spectroscopy excited by X-ray and synchrotron radiation. The binding energy position and intensity of the Co 2p$\text{}_{3}\text{}_{/}\text{}_{2}$ and Ru 3d$\text{}_{5}\text{}_{/}\text{}_{2}$ core levels as well as the shape and structure of the valence band spectra corresponding to the different stages of the deposition were investigated. An observed small positive binding energy shift is a consequence of an increase in the cobalt adatoms coordination number. The core-level shift between bulk and surface Ru atoms is determined as -360 meV. Upon adsorption of cobalt, the interface peak appears with a shift of -(70÷80) meV relative to the bulk one. On the basis of unchanged energy positions and widths of the Ru-derived features of the valence band spectra, a weak interaction between cobalt and substrate is suggested. The measured valence band could be reproduced by superimposing the spectra of the pure elements.
Źródło:
Acta Physica Polonica A; 2007, 111, 2; 263-271
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
U$\text{}_{P}$, 3U$\text{}_{P}$, 11U$\text{}_{P}$: Above-Threshold Ionization Revisited
Autorzy:
Yang, Baorui
Schafer, K. J.
Walker, B.
Kulander, K. C.
Dimauro, L. F.
Agostini, P.
Powiązania:
https://bibliotekanauki.pl/articles/1931385.pdf
Data publikacji:
1994-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
32.80.Fb
31.90.+s
32.80.Rm
Opis:
Angular distributions of very high energy photoelectrons from Xe and Kr, excited by a 50 ps, 1054 um laser, are presented. In Xe strong, narrow structures 45° off the polarization axis appear on above-threshold ionization peaks within a limited energy range centered around 9U$\text{}_{P}$, where U$\text{}_{P}$ is the intensity-dependent ponderomotive energy. Under the same conditions the effect is much weaker in krypton. These structures are discussed using a very simple classical model as well as sophisticated single active electron calculations and the Keldysh-Faisal-Reiss theory. We conclude these structures are the result of single-electron dynamics involving rescattering of a tunneling component of the continuum wave function.
Źródło:
Acta Physica Polonica A; 1994, 86, 1; 41-50
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Role of Hole Localization in the Magneto-Luminescence of a Two-Dimensional Electron Gas
Autorzy:
Calleja, J. M.
Sarkar, D.
van der Meulen, H. P.
Hey, R.
Friedland, K. J.
Ploog, K.
Powiązania:
https://bibliotekanauki.pl/articles/2038327.pdf
Data publikacji:
2004-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.43.Lp
78.55.Cr
73.21.-b
Opis:
We investigate the effect of hole localization on the magneto-luminescence emission of a two-dimensional electron system formed in a modulation-doped semiconductor heterojunction. The emission of heterojunctions containing a dilute delta-layer of Be acceptors at a large distance from the interface is compared with that of Be-free samples. A narrow Fermi-edge singularity emission line is observed at low temperature in Be-doped samples, involving electrons in the second confined state. The evolution of this line in a perpendicular magnetic field shows common characteristics with previously reported results in high mobility samples not containing Be. A new emission line appears abruptly at filling factor 2 originating by the recombination of electrons in the lowest Landau level with free valence holes, independent of the presence of Be. The abruptness of this transition, which is also observed in some samples at filling factor 1, reveals a simultaneous change in the electron system over a macroscopic sample area. The new optical emission shows marked deviations with respect to the single-particle behavior, which are tentatively interpreted as the formation of a complex state involving a free photocreated hole and the electron system. This complex unbinds when the Fermi level crosses the mobility edge.
Źródło:
Acta Physica Polonica A; 2004, 106, 3; 329-340
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exchange Coupling in GdM Compounds
Autorzy:
Buschow, K. H.J.
Grechnev, G. E.
Hjelm, A.
Kasamatsu, Y.
Panfilov, A. S.
Svechkarev, I. V.
Powiązania:
https://bibliotekanauki.pl/articles/1964560.pdf
Data publikacji:
1997-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.En
75.10.Lp
Opis:
The magnetic susceptibility of ferromagnetic GdM alloys (M=Cu$\text{}_{1-x}$Ga$\text{}_{x}$, Mg, Zn) has been investigated under helium gas pressure for temperatures above T$\text{}_{C}$. The evaluated pressure derivatives of the paramagnetic Curie temperature, dlnΘ/dP, appeared to be remarkably different for isovalent GdMg and GdZn compounds (-11.2 and -0.1 Mbar$\text{}^{-1}$, respectively). An analysis of the obtained dlnΘ/dP values for GdCu$\text{}_{1-x}$Ga$\text{}_{x}$ alloys and results of ab initio electronic structure calculations have revealed the essential role of 5d electrons as the mediators of exchange coupling in ferromagnetic GdM compounds. The pressure derivatives of T$\text{}_{C}$ were calculated by employing the modern mean-field theory, as well as the spin-fluctuation model. As a result, good agreement is found with the experimental values of dlnΘ/dP.
Źródło:
Acta Physica Polonica A; 1997, 92, 2; 267-270
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Exciton Binding Energy in Extremely Shallow Quantum Wells
Autorzy:
Kossut, J.
Furdyna, J. K.
Powiązania:
https://bibliotekanauki.pl/articles/1877012.pdf
Data publikacji:
1995-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.20.Dx
71.36.+c
73.61.Ga
Opis:
The usual approach to the problem of excitons in semiconductor quantum wells is to assume that both the electron or the hole are primarily localized in the potential well regions defined by the band offsets, i.e., that the quantum wells are deep. We re-examine the problem of the exciton in the presence of a very shallow square well potential due to the (small) conduction and valence band offsets in a semiconducting heterostructure. We show that the combined effects of the shallow well and the Coulomb interaction between the electron and the hole are equivalent to an effective potential acting on the center-of-mass of a three-dimensional exciton. We calculate the shape of such a potential and show it to be satisfactorily approximated by the potential of a parabolic well.
Źródło:
Acta Physica Polonica A; 1995, 87, 2; 528-532
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multifunctional, Optical Sensor for Analysis of Dynamic Pupillary Light Reflex
Autorzy:
Różanowski, K.
Lewandowski, J.
Murawski, K.
Powiązania:
https://bibliotekanauki.pl/articles/1398782.pdf
Data publikacji:
2015-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.66.Ct
42.30.Va
07.05.Pj
07.07.Df
Opis:
The aim of the publication is to describe the multifunctional optical sensor for analysis of dynamic pupillary light reflex developed by the authors which could be used as an objective indicator of human fatigue. The authors utilized knowledge gained from past experimental studies to develop a sensor, which along with custom software for detection of parameters of dynamic pupillary reflex provides a quick analysis of the human psychophysiological condition. Furthermore, the obtained parameters may also be utilized for medical purposes. The authors present the results of pilot studies prior to the development process of the sensory solution. The obtained result show that the type of light stimulation of the retina has a significant impact on the dynamic parameters of the pupillary reflex. The results played also an important role in shaping the structural assumptions of the sensor, so that it can serve as an indicator of the human fatigue level. The article includes results of experimental research conducted during the testing process of the sensor using various parameters of frequency light excitations, luminance and chrominance.
Źródło:
Acta Physica Polonica A; 2015, 127, 3; 723-729
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Antioxidant Properties and Stability of Geissospermum Reticulatum Tinctures: Lag Phase ESR and Chemometric Analysis
Autorzy:
Sajkowska-Kozielewicz, J.J.
Gulik, K.
Makarova, K.
Paradowska, K.
Powiązania:
https://bibliotekanauki.pl/articles/1032448.pdf
Data publikacji:
2017-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
07.05.Mh
87.64.kh
87.80.Lg
Opis:
Geissospermum species are widely used in folk medicine in the Amazon region. This study was conducted to determine total phenolic and flavonoid contents of three tinctures of Geissospermum reticulatum barks from Peruvian Amazon and correlate these contents to the antioxidant activities and stability. Total content of phenolic compounds (from 694.91 to 1430.67 mg GAE/kg) and flavonoids (575.23-815.65 mg CAE/kg) were found by spectrophotometric methods. The obtained values were interpreted by artificial neural networks to describe the most beneficial conditions for tinctures. All tinctures have demonstrated the maximum of total flavonoid between 14 and 20 weeks of maceration, whereas the maximum of total flavonoid was between 25 and 30. The highest antioxidant properties were exhibited by tinctures in 3 different tests (ferric reducing ability of plasma, DPPH-ESR, oxygen radical absorbance capacity) after 35 weeks of maceration. The principal component analysis was employed to relate contents and properties. Results from the lag phase with α -(4-pyridyl-1-oxide)-N-tert-butylnitrone (POBN) spin trap studies at 60°C demonstrated that the stability of tinctures were related to total phenolic content. Thus, samples with 550-800 mg GAE/kg were more stable than those with higher total phenolic contents. The most beneficial conditions for bark tinctures depend on aimed final products, e.g. maximum of polyphenols or flavonoids and long-term stability. Further studies about content and storage conditions are needed.
Źródło:
Acta Physica Polonica A; 2017, 132, 1; 68-73
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Vapour Absorption in Melamine-Formaldehyde Resin
Autorzy:
Wawryszczuk, J.
Ciesielski, K.
Goworek, J.
Powiązania:
https://bibliotekanauki.pl/articles/2025738.pdf
Data publikacji:
2001
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
36.10.Dr
61.41.+e
66.30.-h
Opis:
The effects of vapour absorption on positron annihilation in cross-linked polymer were investigated. Contrary to linear polymers, absorption of vapour in cross-linked resin leads to the shortening of o-Ps lifetime. In vacuum absorbed molecules diffuse out. At room temperature desorption of hexane and hexanol is not complete; full elimination of absorbed molecules requires sample temperature increase.
Źródło:
Acta Physica Polonica A; 2001, 99, 3-4; 523-528
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Time and Frequency Resolved THz Spectroscopy of Micro- and Nano-Systems
Autorzy:
Kröll, J.
Darmo, J.
Unterrainer, K.
Powiązania:
https://bibliotekanauki.pl/articles/2041637.pdf
Data publikacji:
2005-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.60.-p
Opis:
Terahertz time-domain spectroscopy is applied to characterize ultra-thin metallic layers and nanoscale composite material - single-wall carbon nanotube mat.
Źródło:
Acta Physica Polonica A; 2005, 107, 1; 92-98
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Adsorption of Benzene on 4H-SiC (0001) Surface: First Principles Calculations
Autorzy:
Tokár, K.
Majewski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1403649.pdf
Data publikacji:
2012-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.43.-h
73.20.-r
77.84.Jd
31.15.A-
Opis:
We study adsorption of the benzene molecule on the Si terminated (0001) surface of 4H-SiC by performing first principles calculations in the framework of density functional theory. We find out that chemical reaction leading to the chemisorption of benzene on the surface has endothermic character. The adsorbed benzene molecule is bounded to two surface Si atoms and it does not lose its integrity, however, it undergoes strong deformations and causes distortion of the substrate. We analyze also changes in the electronic structure caused by benzene adsorption.
Źródło:
Acta Physica Polonica A; 2012, 122, 6; 1049-1051
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Ramsauer-Townsend Effect in the Presence of the Minimal Length and Maximal Momentum
Autorzy:
Vahedi, J.
Nozari, K.
Powiązania:
https://bibliotekanauki.pl/articles/1419665.pdf
Data publikacji:
2012-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
04.60.-m
Opis:
The scattering cross-section of electrons in noble gas atoms exhibits the minimum value at electron energies of approximately 1 eV. This is the Ramsauer-Townsend effect. In this letter, we study the Ramsauer-Townsend effect in the presence of both the minimal observable length and the maximal momentum (originating from doubly special theories) through the generalized uncertainty principle.
Źródło:
Acta Physica Polonica A; 2012, 122, 1; 38-41
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical and Optoelectronic Properties of ZnS Nanostructured Thin Film
Autorzy:
Borah, J.
Sarma, K.
Powiązania:
https://bibliotekanauki.pl/articles/1812035.pdf
Data publikacji:
2008-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.61.Ga
73.61.Tm
74.25.Gz
Opis:
ZnS nanocrystalline thin films were grown into the polyvinyl alcohol matrix and were synthesized by chemical route. Films were prepared on glass substrate by varying the deposition parameters and pH of the solution. Nanocrystalline thin film prepared under optimum growth conditions shows band gap value 3.88 eV as observed from optical absorption data. The band gap is found to be higher (3.88 eV) indicating blue shift. The particle size, calculated from the shift of direct band gap, due to quantum confinement effect is 5.8 nm. Photoluminescence spectrum shows the blue luminescence peaks (centered at 425 nm), which can be attributed to the recombination of the defect states. ZnS nanocrystalline thin films are also found to be photosensitive in nature. However, the photosensitivity decreases due to ageing and exposure to oxygen. In case of nanostructured film, the I-V characteristics are observed in dark and under illumination showing photosensitive nature of these films, too. The dark current, however, is found to be greater when observed in vacuum compared to air. Both dark current and photocurrent are found to be ohmic in nature up to a certain applied bias. The observed data shows that nanostructured films are found to be suitable for device application. The surface morphology of the film is also characterized by scanning electron microscope.
Źródło:
Acta Physica Polonica A; 2008, 114, 4; 713-719
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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