Informacja

Drogi użytkowniku, aplikacja do prawidłowego działania wymaga obsługi JavaScript. Proszę włącz obsługę JavaScript w Twojej przeglądarce.

Wyszukujesz frazę "(w.m.)." wg kryterium: Autor


Tytuł:
Biomedical Applications of Synchrotron X-Ray Fluorescence
Autorzy:
Kwiatek, W. M.
Powiązania:
https://bibliotekanauki.pl/articles/1931695.pdf
Data publikacji:
1994-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
07.85.+n
87.59.-e
32.30.Rj
Opis:
Since the exact role of trace elements in living organisms is still not very well known, it is a need of a careful analysis and study on trace element distributions in various biomedical materials. The conventional techniques such as X-ray fluorescence, proton-induced X-ray emission, atomic absorption spectrophotometry do not always give precise determination, especially in microstructures areas. Since synchrotron radiation is very powerful and gives the opportunity to work with micro-beams the synchrotron radiation induced X-ray emission technique has been recently developed. Due to many properties of synchrotron radiation it becomes a very useful tool in science. In this paper a characterization of different apparatus for a trace element analysis as well as several applications are described to show the usefulness of the synchrotron radiation induced X-ray emission.
Źródło:
Acta Physica Polonica A; 1994, 86, 5; 695-703
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electron-Positron Correlations in Paramagnetic Chromium
Autorzy:
Rubaszek, A.
Szotek, Z.
Temmerman, W. M.
Powiązania:
https://bibliotekanauki.pl/articles/2025045.pdf
Data publikacji:
2001
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
71.10.-w
71.60.+z
Opis:
Several approximations for the electron-positron interaction are applied to study the electron-positron momentum densities of paramagnetic chromium. The non-local and state selective electron-positron correlation functions, evaluated within the weighted density approximation, are used to calculate various positron annihilation characteristics in this system. The weighted density approximation results are compared to the experimental data, and to the corresponding results of the independent particle model, local density approximation, and generalised gradient approximation. Also, the semi-empirical results are used in gaining more physical insight and deriving final conclusions of this work.
Źródło:
Acta Physica Polonica A; 2001, 99, 3-4; 473-477
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Čerenkov Waveguide SHG: a Less Critical Way to Reach the Efficiency Peak
Autorzy:
Kotačka, L.
Čtyroký, J.
Hoekstra, H. J. W. M.
Powiązania:
https://bibliotekanauki.pl/articles/2015113.pdf
Data publikacji:
2001-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.65.Ky
42.82.Et
Opis:
It is well known that the conversion efficiency of the SHG in the Čerenkov regime in a waveguide with a nonlinear substrate exhibits a very sharp peak. Its position in a "pump wavelength-guide thickness" diagram follows a modified dispersion relation. A particular material combination exactly determines both the pump wavelength and the guide thickness. The existence of the peak was also experimentally proved with relatively high normalised conversion efficiency of 210%/(cm W). However, in order to achieve such a high conversion efficiency, the required tolerance in the guide thickness should be smaller than 0.5 nm (the FWHM of the peak is approximately 0.8 nm). The allowed variations in refractive indices are also very low (<10$\text{}^{-3}$). The recent theoretical study of the authors showed that an additional layer (idler) inserted into the waveguide facilitates more degrees of freedom which could relax the conditions for reaching the efficiency peak. This paper presents a detailed study of the behaviour of four-layer waveguide devices with a nonlinear substrate which promise a less constrained way to reach the efficiency peak.
Źródło:
Acta Physica Polonica A; 2001, 99, 1; 135-146
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Luminescence and Photoconductivity of Cerium Compounds
Autorzy:
Yen, W. M
Basun, S.
Happek, U.
Raukas, M.
Powiązania:
https://bibliotekanauki.pl/articles/1945563.pdf
Data publikacji:
1996-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.40.+w
78.50.Ec
78.55.Hx
Opis:
The study of the luminescence properties of rare earth doped systems historically focuses on systems which exhibit strong luminescence. More recently, extensive studies on materials with high quantum efficiency are in part motivated by the search for new phosphor and scintillator materials. However, a thorough study of certain systems which show very low quantum yield will certainly lead to a better understanding of phosphor materials and rare earth systems in general. As an example of recent studies which address both the fundamental question of relaxation processes in rare earth doped systems and phosphor applications we present studies on cerium-doped lutetium oxide crystals which are characterized by a complete quenching of the 5d-4f luminescence and compare its optical properties to that of very efficient cerium doped phosphor material, lutetium oxyorthosilicate. To find the mechanisms which lead to the different quantum efficiency in these systems, extensive absorption, photoexcitation and photoconductivity studies were performed on single crystals. We demonstrate that the radically different emission properties of the investigated systems originate in small but crucial differences in the location of the emitting 5d level of the cerium ion with respect to the conduction band of the host - a general result which can be applied to a broad range of materials.
Źródło:
Acta Physica Polonica A; 1996, 90, 2; 257-266
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optically Detected Magnetic Resonance Studies of Te-Related Shallow Donors in Al$\text{}_{x}$Ga$\text{}_{1-x}$As
Autorzy:
Godlewski, M.
Fronc, K.
Chen, W. M.
Monemar, B.
Powiązania:
https://bibliotekanauki.pl/articles/1890838.pdf
Data publikacji:
1991-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.55.Eq
72.20.Jv
76.70.Hb
78.55.Cr
Opis:
The first studies of the Optically Detected Magnetic Resonance (ODMR) of Te-doped (x = 0.42) are presented. The ODMR data indicate an efficient energy transfer between epilayer and GaAs substrate.
Źródło:
Acta Physica Polonica A; 1991, 80, 3; 341-344
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Defects in Dilute Nitrides
Autorzy:
Chen, W. M.
Buyanova, I. A.
Tu, C. W.
Yonezu, H.
Powiązania:
https://bibliotekanauki.pl/articles/2043705.pdf
Data publikacji:
2005-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.72.Ji
71.55.Eq
76.70.Hb
Opis:
We provide a brief review of our recent results from optically detected magnetic resonance studies of grown-in non-radiative defects in dilute nitrides, i.e. Ga(In)NAs and Ga(Al,In)NP. Defect complexes involving intrinsic defects such as As$\text{}_{a}$ antisites and Ga$\text{}_{i}$ self-interstitials were positively identified. Effects of growth conditions, chemical compositions and post-growth treatments on formation of the defects are closely examined. These grown-in defects are shown to play an important role in non-radiative carrier recombination and thus in degrading optical quality of the alloys, harmful to performance of potential optoelectronic and photonic devices based on these dilute nitrides.
Źródło:
Acta Physica Polonica A; 2005, 108, 4; 571-579
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Irreversibility Fields of (Tl$\text{}_{0.5}$Pb$\text{}_{0.5}$) (Sr$\text{}_{0.85}$Ba$\text{}_{0.15}$)$\text{}_{2}$Ca$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{z}$ Film on Polished Silver Substrate
Autorzy:
Woch, W. M.
Zalecki, R.
Kołodziejczyk, A.
Deinhofer, C.
Gritzner, G.
Powiązania:
https://bibliotekanauki.pl/articles/2047336.pdf
Data publikacji:
2007-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.25.Sv
74.78.Bz
74.62.Yb
Opis:
Superconducting (Tl$\text{}_{0.5}$Pb$\text{}_{0.5}$)(Sr$\text{}_{0.85}$Ba$\text{}_{0.15}$)$\text{}_{2}$Ca$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{z}$ film was prepared on a highly polished, untextured silver substrate. A superconducting transition temperature (T$\text{}_{c,50%}$) of 114.7±0.3 K was obtained from the resistance versus temperature measurements for different applied ac currents. The density of the critical current measured by transport method was found to be 11.4×10$\text{}^{3}$ A/cm$\text{}^{2}$ at 77 K in the self field. This value is smaller than the value calculated from ac susceptibility data: 53×10$\text{}^{3}$ A/cm$\text{}^{2}$ at 77 K. The magnetical broadening of the resistivity transition to the superconducting state was observed. The irreversibility fields of the thallium based film were obtained from magnetoresistive measurements for both parallel to the c-axis and parallel to the $ab$ plane showing the anisotropy according to the magnetic field direction. The irreversibility fields as a function of temperature were successfully fitted by the power law.
Źródło:
Acta Physica Polonica A; 2007, 111, 5; 737-743
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
X-Ray Absorption Near Edge Structure and Mössbauer Spectroscopy in Study of Iron Valence States in Tissues
Autorzy:
Dziedzic-Kocurek, K.
Banaś, A.
Kwiatek, W. M.
Stanek, J.
Powiązania:
https://bibliotekanauki.pl/articles/2044673.pdf
Data publikacji:
2006-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.18.Fs
61.10.Ht
Opis:
X-ray absorption near edge structure Fe K-edge spectra and $\text{}^{57}$Fe Mössbauer spectra of selected standard compounds were recorded at room temperature. Valence and spin states of Fe in these samples known from Mössbauer spectroscopy were correlated with the shapes of X-ray absorption near edge structure spectra in search of possible application of X-ray absorption near edge structure spectroscopy as analytical tool determining local electronic states of iron in tissues. As an example, the X-ray absorption near edge structure spectra of healthy and cancerous tissues of prostate are shown, suggesting Fe$\text{}^{3+}$ in cancerous tissues.
Źródło:
Acta Physica Polonica A; 2006, 109, 3; 341-345
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact Ionization Driven Chaotic Photoluminescence Oscillations in Ga$\text{}_{0.47}$In$\text{}_{0.53}$As
Autorzy:
Godlewski, M.
Fronc, K.
Gajewska, M.
Chen, W.M.
Monemar, B.
Powiązania:
https://bibliotekanauki.pl/articles/1888119.pdf
Data publikacji:
1991-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.35.+z
72.70.+m
76.90.+d
Opis:
A new application of the Optically Detected Cyclotron Resonance (ODCR) is presented. We report impact ionization studies of bound exciton: (BE) and shallow donor related recombination processes in Ga$\text{}_{0.47}$In$\text{}_{0.53}$As. An appearance of chaotic oscillations in photoluminescence (PL) intensity is observed under condition of impact ionization of deeper donors.
Źródło:
Acta Physica Polonica A; 1991, 80, 2; 271-274
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Elemental Mapping of Prostate Tissue by Micro-SRIXE
Autorzy:
Banaś, A.
Banaś, K.
Falkenberg, G.
Dyduch, G.
Kwiatek, W. M.
Powiązania:
https://bibliotekanauki.pl/articles/2044669.pdf
Data publikacji:
2006-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
87.64.-t
Opis:
Synchrotron radiation-induced X-ray emission is now a proven analytical method for the determination of trace elements. Better insight of the role of trace elements in tissue samples can be gained by acquiring complete distribution maps of these elements. Our approach is based on the acquisition of digital maps. In this contribution we present two different methods for obtaining normalization matrix: first - based on argon intensity in the single spectrum and second - based on changes of beam current intensity. The region for the scan was carefully chosen according to the histological view of the sample. A total area was scanned with a step size of 15 μm in each direction and measuring time of 30 s per pixel. The thickness of the samples was 15 μm. A polycapillary was used for beam focusing. At the energy of 18 keV the beam size on the sample was approximately 15 μm which is of the order of a cell diameter.
Źródło:
Acta Physica Polonica A; 2006, 109, 3; 323-328
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
AlGaAs to GaAs Energy Transfer Mechanisms in AlGaAs/GaAs Structures
Autorzy:
Karpińska, K.
Godlewski, M.
Żytkiewicz, Z. R.
Chen, W. M.
Weber, E. R.
Powiązania:
https://bibliotekanauki.pl/articles/1921617.pdf
Data publikacji:
1992-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.20.Jv
76.70.Hb
78.55.Cr
Opis:
The results of photoluminescence and optically detected cyclotron resonance experiments are presented for thick AlGaAs epilayers grown by liquid phase electroepitaxy method on GaAs:Cr substrate. These results indicate an efficient energy transfer from excited AlGaAs to GaAs.
Źródło:
Acta Physica Polonica A; 1992, 82, 4; 713-716
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Magnetic Field on Resistive Transition of Thin Film Thallium Based Superconductors
Autorzy:
Woch, W. M.
Zalecki, R.
Kołodziejczyk, A.
Chmist, J.
Heiml, O.
Gritzner, G.
Powiązania:
https://bibliotekanauki.pl/articles/2041534.pdf
Data publikacji:
2004-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.78.Bz
74.25.Qt
74.62.Yb
Opis:
The temperature and magnetic field dependences of a.c. resistance of c-axis oriented (Tl$\text{}_{0.5}$Pb$\text{}_{0.5}$)(Sr$\text{}_{0.8}$Ba$\text{}_{0.2}$)$\text{}_{2}$Ca $\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{x}$ and (Tl$\text{}_{0.6}$Pb$\text{}_{0.24}$Bi$\text{}_{0.16}$)(Sr$\text{}_{0.9}$Ba$\text{}_{0.1}$)$\text{}_{2}$Ca$\text{}_{2}$Cu$\text{}_{3}$ O$\text{}_{x}$ thin films as well as of (Tl$\text{}_{0.5}$Pb$\text{}_{0.5}$)(Sr$\text{}_{0.8}$Ba$\text{}_{0.2}$)$\text{}_{2}$Ca$\text{}_{ }$2Cu$\text{}_{3}$O$\text{}_{x}$ bulk sample from 77 K to room temperature and in magnetic fields from zero to 3000 Oe were measured and analyzed. The magnetic field and temperature dependence of the resistive superconducting transition and irreversibility field were discussed both in the flux-creep model and in the superconducting liquid vortex state model. The temperature width of resistive transition was explained taking advantage of the Ambegaokar and Halperin model of the resistance of superconducting Josephson weak links and barrier of vortex motion presented by Tinkham. The irreversibility field was described by an exponential formula.
Źródło:
Acta Physica Polonica A; 2004, 106, 5; 785-791
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Preliminary Study on Chemical Speciation of Sulphur in Cancerous Tissues
Autorzy:
Kwiatek, W. M.
Banaś, A.
Banaś, K.
Kisiel, A.
Cinque, G.
Falkenberg, G.
Powiązania:
https://bibliotekanauki.pl/articles/2044744.pdf
Data publikacji:
2006-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
87.64.Gb
Opis:
Sulphur is vital for almost all living organisms by participating in a wide variety of metabolic processes. Nevertheless its biochemistry is only partially understood, due to it a few tools such as X-ray absorption near edge structure may be used to determine its chemical speciation in biological system. In this paper we focused on analysis of composition and elemental distribution in tissue structures of biological samples. We examined cancerous and non-cancerous prostate tissues. Experiments were carried out on the L-beam line at the HASYLAB, DESY (Hamburg, Germany) and DAΦNE-Light Facility at the Laboratori Nationali di Frascati (Frascati, Italy). Synchrotron radiation induced X-ray emission measurements reveal the significant differences in concentration of sulphur between cancerous and non-cancerous tissues. X-ray absorption near edge structure spectra show two main types of sulphur that are represented by X-ray peaks at 2476 eV and 2484 eV. This suggests that different sulphur components are present in the measured samples.
Źródło:
Acta Physica Polonica A; 2006, 109, 3; 383-387
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electronic Properties of High-Temperature Superconductor DyBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7}$ from Critical Fields and Specific Heat Studies
Autorzy:
Kołodziejczyk, A.
Kozłowski, A.
Chmist, J.
Zalecki, R.
Ściężor, T.
Tarnawski, Z.
Woch, W. M.
Powiązania:
https://bibliotekanauki.pl/articles/1929388.pdf
Data publikacji:
1993-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
74.70.-b
76.30.-v
Opis:
The lower and upper critical fields, as well as the specific heat were measured as a function of temperature for good quality DyBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7}$ high-temperature superconductor in the vicinity of superconducting transition temperature T$\text{}_{c}$ = 91.2 K. The number of superconducting and normal state electronic quantities were determined basing on the Ginzburg-Landau-Abrikosov-Gorkov theory. It is argued that on the basis of this BCS-like theory one can describe the superconducting properties and, in combination with some information on the electronic structure, also the magnetic properties of high-temperature superconductors.
Źródło:
Acta Physica Polonica A; 1993, 84, 1; 127-138
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Distinguishing Prostate Cancer from Hyperplasia
Autorzy:
Kwiatek, W. M.
Banaś, A.
Banaś, K.
Podgórczyk, M.
Dyduch, G.
Falkenberg, G.
Gajda, M.
Cichocki, T.
Powiązania:
https://bibliotekanauki.pl/articles/2044731.pdf
Data publikacji:
2006-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
87.64.-t
Opis:
The prostate gland is the most common site of neoplastic disorders in men. The knowledge of the pathogenesis of benign prostate hyperplasia and prostate cancer is still under investigation. X-ray fluorescence analysis using synchrotron radiation seems to be an appropriate technique to study the elemental composition of biological tissues. The measurements presented in this paper were carried out on the L-beam line at the HASYLAB, DESY (Germany). The observed concentrations of Fe, Cu, Mn, and Zn are significantly higher in cancerous tissues, as compared to normal and hyperplastic ones. Our results reveal also the existence of the two types of hyperplasia.
Źródło:
Acta Physica Polonica A; 2006, 109, 3; 377-381
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies