Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl
Preferences help
Polish version English version Language
enabled [disable] Abstract
Number of results

Results found: 8

Number of results on page
first rewind previous Page / 1 next fast forward last

Search results

help Sort By:

help Limit search:
first rewind previous Page / 1 next fast forward last
1
Content available remote

Localized Vibrational Modes of Interstitial Oxygen in Si_{x}Ge_{1-x} Alloys

100%
Lorenc M., Humlíček J.
Acta Physica Polonica A
|
1998
|
vol. 94
|
issue 3
436-440
EN
We study infrared-active vibrations of interstitial oxygen in Czochralski-grown samples of Si_{x}Ge_{1-x} alloys with the silicon content from 0 to 1 between room and liquid nitrogen temperature. The measurements were performed on a large series of samples including single crystals of Si and Si-rich alloys, and polycrystalline samples of alloys with a higher Ge content. We focus on quantitative data on the compositional and temperature evolution of the strongest absorption band above 1100 cm^{-1}, related to the asymmetric stretching of the Si_{2}O pseudomolecule. We have also observed a pronounced Fano-like resonance centered at 520 cm^{-1}.
2
Content available remote

Vibrational Modes in Si_{x}Ge_{1-x} Alloys: Temperature and Compositional Dependence

100%
Lorenc M., Humlíček J.
Acta Physica Polonica A
|
1997
|
vol. 92
|
issue 5
899-902
EN
We report infrared absorption spectra of crystalline Si_{x}Ge_{1-x} alloys with silicon content 0 ≤ x ≤ 1 at room and liquid nitrogen temperature. We covered the spectral range from 375 to 1200 cm^{-1} that includes the "Si-Ge" and "Si-Si" single-phonon transitions, the continuum of two-phonon processes, and the localized mode of interstitial oxygen. We study the change of vibrational structure and correlation between reference (pure Si and Ge) and alloy spectra. We observed shifts to lower wave numbers by about 1 cm^{-1} of the two-phonon absorption bands per 1% increase in germanium concentration. Pronounced changes of the vibrational spectra upon lowering the temperature were detected.
3
Content available remote

The Analysis of Mechanical Vibrations and Acoustic Pressure Level οf a Transformer Model

81%
Boczar T., Borucki S., Cichon A., Lorenc M.
Acta Physica Polonica A
|
2008
|
vol. 114
|
issue 6A
A-21-A-26
EN
The paper presents the results of vibroacoustic investigations and the measurements of the acoustic pressure level (noise) of a transformer model. The measurements were taken at a full transformer load in two operation conditions: at a producer packeted core and at unpacketed core. Unpacketing consisted in loosing the screws pressing the particular core plates. Mechanical vibrations were registered and the acoustic pressure level was measured. The vibroacoustic analysis results are presented in the form of frequency spectra and the results of the acoustic analysis of the transformer under study are shown by determining corrected values of the acoustic pressure level and by a frequency analysis.
4
Content available remote

Acoustic Spectra of Ultrasound Induced Cavitations in Insulating Oils

81%
Szmechta M., Zmarzły D., Boczar T., Lorenc M.
Acta Physica Polonica A
|
2008
|
vol. 114
|
issue 6A
A-231-A-238
EN
Acoustic emission measurement results of acoustically induced cavitation bubbles in insulating oil are presented in this paper. Spectral analysis of acquired by a broadband transducer acoustic emission signals is proposed as a diagnostic tool for estimation of aging properties of mineral insulating oils. The article describes the main parts of the designed and built measurement apparatus used for acoustic cavitation investigation in insulating oils. In this note representative results of the experimental data taken from the apparatus are shown.
5

Cytokine production by human leukocytes with different expressions of natural antiviral immunity and the effect of antibodies against interferons and TNF-alpha

61%
Orzechowska B., Antoszkow Z., Siemieniec I., Lorenc M., Jatczak B., Blach-Olszewska Z.
Archivum Immunologiae et Therapiae Experimentalis
|
2007
|
vol. 55
|
issue 2
111-117
EN
Introduction: Two activities of innate antiviral immunity were studied: the resistance of human peripheral blood mononuclear cells (PMBCs) ex vivo to viral infection and the production of cytokines. Materials and Methods: Samples of blood were taken from healthy blood donors and from persons with frequent infections of the upper respiratory system. PMBCs were isolated by gradient centrifugation. Vesicular stomatitis virus (VSV) was used as the indicatory virus to infect PMBCs. The cytokines: IFN, TNF, and IL-6 were titrated by biological methods and IL-10 by ELISA. Results: Blood donors were divided for two groups: those with VSV-resistant and those with VSV-sensitive PMBCs and secretion of cytokines by them was compared. The resistant PMBCs produced more cytokines than the sensitive ones. A statistically significant difference, was found only in the case of the IFNs. To examine the contribution of IFNs and TNF in maintaining resistance, leukocytes from both groups were treated with specific anti-cytokine antibodies. The authors' previous study showed that the elimination of spontaneous IFN-alpha IFN-beta, IFN-gamma, and TNF-alpha from resistant leukocytes resulted in increased VSV replication This indicates the important role of cytokines. In VSV-sensitive PMBCs, anti-IFN-alpha showed the opposite effect (decreased virus replication). In the absence of spontaneous IFN-alpha, disturbances in cytokine production were observed. Conclusions: Complete resistance of PMBC to VSV infection is accompanied by higher cytokine release, The paradoxical effect of anti-IFN-alpha on virus replication in leukocytes sensitive to viral infection may be attributed to changes in the cytokine profile balance, i.e. high TNF production by VSV-infected leukocytes and a complete reduction of IL-6 production.
6
Content available remote

White Light Snapshot of Non-Equilibrium High-Spin State in a Molecular Crystal

61%
Kaszub W., Collet E., Cailleau H., Servol M., Boillot M., Tissot A., Lorenc M.
Acta Physica Polonica A
|
2012
|
vol. 121
|
issue 2
324-327
EN
The spin-crossover compound [(TPA)Fe(TCC)]PF_6 was experimentally investigated using time-resolved optical pump and supercontinuum probe technique. Changes of VIS optical density at thermal equilibrium of a crystal with different high-spin/low-spin fractions are compared to changes recorded picoseconds after femtosecond laser excitation. A white light snapshot of the high-spin state at 180 K is extracted from time-resolved spectra. Our results indicate that the temperature of the electronic state affects the absorption spectra of high- and low-spin states.
7
Content available remote

PIPT from the Beginning to Future

61%
Cailleau H., Luty T., Koshihara S., Servol M., Lorenc M., Buron-Le Cointe M., Collet E.
Acta Physica Polonica A
|
2012
|
vol. 121
|
issue 2
297-306
EN
The birth of the field of photoinduced phase transitions was strongly influenced by the conceptual viewpoint expressed by Professor Y. Toyozawa on the condensation of relaxed excitons. Since this first period, twenty years ago, this young field has been expanding rapidly along a diversity of directions. Nowadays, it goes hand in hand with the challenges of today's science: emergence, nonlinearity, coherence, far away from equilibrium, for example. The control of the functionality of a material via photoexcited states poses many new fundamental questions. Some of them will be overviewed: (i) the nature of the control parameters and the nature of the relevant collective variables, especially the order parameters, which characterize the evolution of the system, (ii) the difference between photoinduced transformations under continuous light irradiation and those resulting from an ultrashort laser pulse, (iii) the physical mechanisms of ultrafast photoinduced phase transitions from the formation and proliferation of phototransformed entities to the softening of a collective mode.
8
Content available remote

Time-Resolved Pump-Probe Diffraction Experiment at SOLEIL Synchrotron: Photoinduced Spin Transition in the Molecular Crystal [TPA Fe(III) TCC] PF_6

42%
Laulhé C., Ravy S., Fertey P., Elkaim E., Legrand F., Féret P., Hollander P., Hustache S., Bordessoule M., Ricaud J., Collet E., Lorenc M., Buron-Le Cointe M., Cailleau H., Tissot A., Boillot M.
Acta Physica Polonica A
|
2012
|
vol. 121
|
issue 2
332-335
EN
We present the first time-resolved pump-probe experiment performed at synchrotron SOLEIL at the CRISTAL diffraction beamline. The time-resolved setup will be used in the near future for sub-ns time resolution experiments. We studied spin state switching in a [TPA Fe(III) TCC] PF_6 single crystal as induced by a ≈6 ns laser pulse (1064 nm), by measuring the 3D diffraction volume of the 002 Bragg reflection as a function of time after excitation. The intensity profiles (rocking curves) are found to evolve at two characteristic timescales, namely hundreds of ns and few μs, exhibiting subtle profile changes and peak broadenings. Consistently with previous studies, we interpret these features as due to structural inhomogeneities related to laser-induced deformation wave propagation and heat diffusion, which both start from the absorbing sites.
first rewind previous Page / 1 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.