Informacja

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

English (EN)·Polski (PL)·Yкраїнський (UK)
Przejdź do strony domowej biblioteki Centralna Biblioteka Wojskowa Link otwiera się w nowym oknie Logo biblioteki Prolib Integro - strona głównaCentralna Biblioteka Wojskowa

Wyszukujesz frazę "76.60.-k" wg kryterium: Temat

  Lista filtrów
Wyrównaj
Wyświetlanie 1-15 z 44
Tytuł:
Local Magnetic and Electronic Properties of the A$\text{}_{2}$FeM'O$\text{}_{6}$ (A = Ba, Sr, Ca, M' = Mo, Re) Double Perovskites
Autorzy:
Zając, D.
Sikora, M.
Prochazka, V.
Borowiec, M.
Stępień, J.
Kapusta, Cz.
Riedi, P. C.
Marquina, C.
De Teresa, J. M.
Ibarra, M. R.
Powiązania:
https://bibliotekanauki.pl/articles/2047344.pdf
Data publikacji:
2007-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.-m
76.60.-k
76.60.Jx
78.80.En
Opis:
The results of a combined NMR, X-ray absorption spectroscopy and X-ray magnetic cirrcular dichroism study of the AA'FeMoO$\text{}_{6}$ and AA'FeReO$\text{}_{6}$ double perovskites are presented. They revealed a dependence of electronic and magnetic properties, including a d-electron transfer between Fe and Mo sites, on the structural tolerance factor. The maximum value of the 4d Mo electron occupation and the corresponding Mo moment is obtained for the tolerance factor of unity. This corresponds to the maximum strength of the magnetic interaction and, respectively, to the Curie temperature. The dominant T$\text{}^{5}\text{}^{/}\text{}^{2}$ type temperature dependence of the Mo hyperfine field reveals the half-metallicity of the AA'FeMoO$\text{}_{6}$ compounds. Antisite defects and antiphase boundaries have been identified in NMR measurements and the strength of their magnetic coupling have been determined. A considerable orbital contribution to the Re and Fe magnetic moments were found in the NMR and X-MCD measurements on the AA'FeReO$\text{}_{6}$ compounds. Its magnitude decreases with increasing structural tolerance factor and is correlated with their magnetic anisotropy.
Źródło:
Acta Physica Polonica A; 2007, 111, 6; 797-820
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
NMR Study of (Sr,Ba,La)$\text{}_{2}$Fe$\text{}_{1+y}$Mo$\text{}_{1-y}$O$\text{}_{6}$ Double Perovskites
Autorzy:
Zając, D.
Kapusta, Cz.
Riedi, P. C.
Sikora, M.
Oates, C. J.
Rybicki, D.
De Teresa, J. M.
Serrate, D.
Marquina, C.
Ibarra, M. R.
Powiązania:
https://bibliotekanauki.pl/articles/2041522.pdf
Data publikacji:
2004-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.25.+z
76.60.-k
78.70.Gq
75.47.Gk
Opis:
The $\text{}^{95}$Mo and $\text{}^{97}$Mo NMR spin-echo study of (Sr,Ba,La)$\text{}_{2}$Fe$\text{}_{1 +y}$Mo$\text{}_{1-y}$O$\text{}_{6}$ double perovskites is reported. Powder samples of Ba$\text{}_{1.44}$Sr$\text{}_{0.36}$La$\text{}_{0.2}$FeMoO$\text{}_{6}$ and (Ba$\text{}_{0.8}$Sr$\text{}_{0.2}$)$\text{}_{2-2x}$La$\text{}_{x}$#$\text{}_{x}$ Fe$\text{}_{1+y}$Mo$\text{}_{1-y}$O$\text{}_{6}$, where# denotes vacancies, for: x=0, y=0; x=0.1, x=0.2 and x=0.3, y=0 and y=0.2 were measured at 4.2 K and no applied magnetic field. NMR signals are observed at 55-100 MHz for the main line and 30-55 MHz for low-frequency satellite. The main line and the satellite are attributed to the ideal and defect positions of Mo atoms. La and vacancy doping introduce more defects, however, increasing the Fe/Mo ratio decreases the amount of defect Mo sites. La doping causes a satellite pattern at the high frequency side of the spectrum, which is related to different numbers of the La next neighbours. The effect is attributed to an increase in the electron density and the corresponding magnetic moment at the adjacent Mo sites and reveals a local character of the electron doping.
Źródło:
Acta Physica Polonica A; 2004, 106, 5; 759-765
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Molecular Dynamics in Biological Systems Observed by NMR Relaxation in a Rotating Frame
Autorzy:
Wierzuchowska, D.
Skórski, L.
Blicharska, B.
Powiązania:
https://bibliotekanauki.pl/articles/1490095.pdf
Data publikacji:
2012-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.60.-k
76.90.+d
Opis:
NMR relaxation provides powerful tools for obtaining information on three-dimensional structures, dynamic properties and intermolecular interactions of biological macromolecules. One of these methods, called dispersion profile, is based on measuring the field dependence of spin-relaxation rates in the rotating frame, $R_{1ρ} = 1//T_{1ρ}$, in the presence of a low magnetic field $B_1$. In the presented study we use this method for investigation of molecular dynamics in protein samples. Dispersion profiles can be predicted theoretically and using two models, assuming either dipolar interaction between protons or power law dispersion, we have evaluated some molecular dynamic parameters of water adsorbed on protein surface. Our researches are focused on the connections of obtained parameters of molecular dynamics with conformation changes of protein. We have calculated the correlation times and power parameters for samples of lyophilized powder of albumins (egg white and bovine and rabbit blood serum) and lysozyme, as well as its aqueous solutions. Analysis of these parameters yields valuable information on the molecular nature of investigated biological systems. We also used this method to analyze experimental data of $T_{1ρ}$ obtained by other authors for bovine serum albumin and we have found good accordance with their conclusions concerning molecular dynamics of proteins.
Źródło:
Acta Physica Polonica A; 2012, 121, 2; 434-438
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Molecular Dynamics of Proteins Investigated by NMR Relaxation Methods
Autorzy:
Wierzuchowska, D.
Blicharska, B.
Powiązania:
https://bibliotekanauki.pl/articles/1360657.pdf
Data publikacji:
2014-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.60.-k
76.90.+d
Opis:
The nuclear magnetic resonance relaxation times of solvent water nuclei are known to decrease upon addition of diamagnetic solute protein. For this reason NMR relaxation methods are able to provide information on molecular dynamics changes of water protons and their interaction with macromolecules' surfaces. We present results of measurements of relaxation rates $R_1$ = 1/$T_1$, $R_2$ = 1/$T_2$ and $R_{1ρ}$ = 1/$T_{1ρ}$ in the rotating frame for three proteins: chicken egg white lysozyme, egg white albumin, and bovine serum albumin, obtained at proton resonant frequency of 60 MHz. Besides the relaxation rates dependences on concentration in the 4-23% (g/100 g solution) range, the analysis of the Carr-Purcell-Meiboom-Gill CPMG multi-echo $T_2$ experiments with variable pulse rate τ was performed. The dependences of relaxation rates on protein concentration are linear at low concentration. When protein concentration increases the slope of the straight line rapidly changes at so-called "critical" concentration which depends on MW of the diluted protein. Investigated dispersion of $T_2$, obtained using the CPMG method with a variable pulse rate, for concentrations higher and lower than the "critical" one, exhibits unequal behavior. At high concentration one-exponential curves and at low concentration two-exponential curves correspond closely with experimental data. The obtained parameters of exponents allow an estimation of the ratio of the amount of water with the determined motion freedom, that is free and bounded water, in solution. We showed that the CPMG dispersion method applied to aqueous protein solutions may widen the current understanding of the nature of molecular dynamics of hydrated water protons in non-perturbed environment.
Źródło:
Acta Physica Polonica A; 2014, 125, 4; 907-910
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
NMR Relaxation Measurements as a Tool for Observation of Oxidative Processes
Autorzy:
Wierzuchowska, D.
Skórski, L.
Blicharska, B.
Powiązania:
https://bibliotekanauki.pl/articles/1398821.pdf
Data publikacji:
2016-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.60.-k
76.90.+d
76.30.Rn
Opis:
Water proton relaxation times, T₁ and T₂, were measured to assess the kinetics of the oxidative processes in biological samples. The oxidation in aqueous solutions of albumins was promoted by an addition of 3% hydrogen peroxide (H₂O₂). Immediately following this addition a sharp exponential decrease of both relaxation times was observed. As we confirmed experimentally, the time course of relaxation depended on several essential factors like structure and the concentration of proteins and also the presence of antioxidants added to solution. In experiments with protein solutions containing a small amount of ascorbic acid, after reaching a minimum, relaxation time increased towards the initial (pre-addition H₂O₂) values. We conclude that this T₁ and T₂ recovery is a consequence of the presence of antioxidants and may be used to evaluate its action. This study demonstrates that nuclear magnetic resonance (NMR) relaxation measurements may be useful in evaluating free radicals reactions and antioxidants capacity.
Źródło:
Acta Physica Polonica A; 2016, 129, 2; 226-228
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Observation of Antioxidants Activity using NMR Relaxation Measurements
Autorzy:
Wierzuchowska, D.
Witek, M.
Blicharska, B.
Powiązania:
https://bibliotekanauki.pl/articles/1030645.pdf
Data publikacji:
2018-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.60.-k
76.90.+d
76.30.Rn
Opis:
Formation of free radicals in biological solutions leads to the changes in water protons relaxation times. Therefore, NMR relaxation measurements were used to investigate kinetics of oxidation processes induced by the addition, in low amounts, of hydrogen peroxide (H_2O_2) to aqueous protein solution and to blood serum. The measured relaxation times were not stable over time because of the progressive formation of free radicals and their damaging action to the protein structure. The addition of antioxidants (ascorbic acid, gallic acid etc.) changed the relaxation time courses due to free radical scavenging. Similar time courses, thus anti-oxidant actions, were observed in various blood serum without antioxidant additive. Moreover, the observed kinetics of spin-lattice relaxation time (T_1) depended on several factors, such as: structure and concentration of protein solutions and activity and concentration of the added antioxidants.
Źródło:
Acta Physica Polonica A; 2018, 133, 2; 289-291
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Solid State $\text{}^{13}C$ NMR Study of Modified Polyhydroxybutyrate
Autorzy:
Vrábel, P.
Hronský, V.
Fričová, O.
Koval'aková, M.
Chodák, I.
Alexy, P.
Powiązania:
https://bibliotekanauki.pl/articles/1382700.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.41.+e
76.60.-k
81.05.Lg
Opis:
Structural changes in polyhydroxybutyrate (PHB) brought about by addition of chain extender and/or plasticizer were studied using $\text{}^{13}C$ MAS NMR spectra, which were measured using the direct polarization technique at 30 and 98°C. Four resonances associated with the CO, CH, $CH_{2}$ and $CH_{3}$ groups of PHB were observed in the spectra. The $CH_{3}$ resonance appearing at 98°C shows splitting into two lines related to the crystalline and amorphous regions. Analysis of the $CH_{3}$ resonances made it possible to estimate the influence of applied modifications on crystallinity and distribution of conformations in amorphous and crystalline domains of PHB samples.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 419-420
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Stochastic Dynamics on the Nuclear Magnetic Resonance in a Field Gradient
Autorzy:
Tóthová, J.
Lisý, V.
Powiązania:
https://bibliotekanauki.pl/articles/1032635.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.60.-k
76.60.Lz
05.40.-a
05.10.Gg
Opis:
In the present contribution, the attenuation function S(t) for an ensemble of spins in a magnetic-field gradient is calculated through an accumulation of the phase shifts in the rotating frame resulting from the changes of the particle displacements. The found S(t) is applicable for any kind of the stochastic motion of spins, including their non-Markovian dynamics with memory. Depending on the considered system, both the classical expressions valid for normal diffusion at long times and new formulae for the short-time Brownian motion can be obtained. Our method is also applicable to the NMR pulse sequences based on the refocusing principle. This is demonstrated by describing the spin echo experiment developed by Hahn.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1111-1113
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
$\text{}^{57}$Fe Hyperfine Field Anisotropy in Ferrites and its Relation to the Non-Uniformity of the Ionic Surrounding
Autorzy:
Štepánková, H.
Englich, J.
Kohout, J.
Powiązania:
https://bibliotekanauki.pl/articles/2013366.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.60.-k
75.50.Gg
Opis:
The hyperfine field anisotropy tensors, obtained from analysis of $\text{}^{57}$Fe NMR spectra for iron sites in various magnetic oxides (barium hexaferrite, lithium spinel, magnetite and yttrium-iron garnet) were used to investigate the relation between the hf anisotropy and surrounding ionic arrangement. While a reasonable correlation has been found when the distribution of the nearest cations was considered, no correlation was obtained between the hyperfine field anisotropy and the positions of the nearest oxygen anions.z
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 757-760
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dependence of Order and Dynamics in Polymers and Elastomers under Deformation Revealed by NMR Techniques
Autorzy:
Stapf, S.
Kariyo, S.
Powiązania:
https://bibliotekanauki.pl/articles/2043553.pdf
Data publikacji:
2005-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Lg
82.35.Lr
76.60.-k
61.25.Hq
36.20.Ey
81.40.Lm
Opis:
Uniaxial stretching and swelling are considered as two limiting cases of deformations of elastomers. Under both conditions, the molecular dynamics is changed with respect to the behavior that describes the undisturbed, equilibrium elastomer. Particularly the spectrum of segmental motions, which reveals itself in the frequency-dependence of the longitudinal NMR relaxation time, is discussed in this study, but also order effects expressed via the dipolar coupling strength are investigated. For stretched elastomers, a significant change of the relaxation dispersion is found for three different types of rubber; it is a consequence of a change of the mode spectrum of segmental motions that becomes obvious at low frequencies (below 1 MHz at room temperature). In swollen elastomers, on the other hand, a cross-over towards a behavior expected for semi-dilute solutions is found, and a comparison to solutions of uncross-linked polymers reveals a significant effect of the cross-links only in the kHz range. A much more pronounced difference between elastomers and polymer solutions, however, is found from double-quantum encoded NMR measurements where the residual order introduced by the presence of permanent cross-links is maintained even in the presence of solvent.
Źródło:
Acta Physica Polonica A; 2005, 108, 2; 247-259
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Tuned Probehead for NMR Spectroscopy in Magnetically Ordered Materials
Autorzy:
Sedlák, B.
Kouřil, K.
Chlan, V.
Řezníček, R.
Křišťan, P.
Pfeffer, M.
Englich, J.
Štěpánková, H.
Powiązania:
https://bibliotekanauki.pl/articles/1534619.pdf
Data publikacji:
2010-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
07.57.Pt
76.60.-k
76.60.Lz
Opis:
This work describes the design of a tuned NMR probehead that was developed for measurement of very broad spectra in fully impedance matched mode. The probehead is constructed as an insert of continuous flow cryostat to allow operation down to helium temperatures. Properties of the probehead are demonstrated on $\text{}^{57}Fe$ NMR in magnetic oxide with spinel structure.
Źródło:
Acta Physica Polonica A; 2010, 118, 5; 924-925
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A $\text{}^{55}$Mn NMR Study of La$\text{}_{0.33}$Nd$\text{}_{0.33}$Ca$\text{}_{0.34}$Mn O$\text{}_{3}$ with $\text{}^{16}$O and $\text{}^{18}$O
Autorzy:
Rybicki, D.
Kapusta, Cz.
Riedi, P. C.
Oates, C. J.
Sikora, M.
Zając, D.
De Teresa, J. M.
Marquina, C.
Ibarra, M. R.
Powiązania:
https://bibliotekanauki.pl/articles/2037128.pdf
Data publikacji:
2004
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.60.-k
75.47.Gk
Opis:
A $\text{}^{55}$Mn NMR study of $\text{}^{16}$O and $\text{}^{18}$O containing La$\text{}_{0.33}$Nd$\text{}_{0.33}$Ca$\text{}_{0.34}$Mn O$\text{}_{3}$ is reported. The spin-echo spectra measured at 4.2 K and zero field consist of a double exchange line corresponding to the ferromagnetic metallic regions. The line intensity is more than an order of magnitude lower for the $\text{}^{18}$O compound, which indicates an order of magnitude lower content of the ferromagnetic metallic phase in this compound. The frequency dependence of the spin-spin relaxation time T$\text{}_{2}$ shows a pronounced minimum at the center of the double exchange line of both compounds due to the Suhl-Nakamura interaction, which indicates that the ferromagnetic metallic regions are at least 10~nm in size. The results are discussed in terms of the influence of oxygen isotopic substitution on phase segregation.
Źródło:
Acta Physica Polonica A; 2004, 105, 1-2; 183-188
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Free Volume of Condensed Phases Confined in a Nanopore as Seen by Computer Simulations and Compared to PALS
Autorzy:
Račko, D.
Powiązania:
https://bibliotekanauki.pl/articles/1196175.pdf
Data publikacji:
2014-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
61.20.Ja
76.60.-k
64.70.pm
Opis:
In this contribution the free volume of glycerol phase confined in a nanopore in a wide temperature range is computed. The computed free volume is compared to the previously computed values in the glycerol bulk. The mean cavity volumes are also discussed with the experimental measurements by positronium annihilation lifetime spectroscopy. The computer simulations show that in the case of the confined glycerol phase the mean cavity volumes are larger than in the simulated bulk, and also the temperature dependence has a different qualitative behavior; the computed data are in agreement with experimental measurements performed for glycerol in a pore of comparable size with diameter 6 nm. The simulations also indicate that an aspect of filling a pore is important for experimentalists. In the case of a perfectly sealed pore the cavity volume is observed to rise with decreasing temperature.
Źródło:
Acta Physica Polonica A; 2014, 125, 3; 785-788
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Alkali Intercalated C$\text{}_{60}$: NMR and Magnetic Susceptibility Studies
Autorzy:
Rachdi, F.
Goze, C.
Reichenbach, J.
Lukyanchuk, J.
Kirova, N.
Zimmer, G.
Mehring, M.
Molinié, P.
Powiązania:
https://bibliotekanauki.pl/articles/1933392.pdf
Data publikacji:
1995-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.60.-k
74.70.Wz
Opis:
We report on $\text{}^{13}$C NMR measurements on potassium intercalated C$\text{}_{60}$ compounds. By using high resolution NMR technique we were able to characterize the different thermodynamically stable phases. The effects of the intercalation on the molecular dynamics as well as on the electronic properties will be discussed. We also performed the magnetic susceptibility measurements on Rb$\text{}_{4}$C$\text{}_{60}$ compound, which reveal the activation temperature behavior with the activation energy about 1200 K. By comparison with the NMR and ESR data of the same sample we conclude that the additional electrons are localized on the C$\text{}_{60}$ molecule and form the spin singlet ground state.
Źródło:
Acta Physica Polonica A; 1995, 87, 4-5; 861-867
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
SWR Studies of Higher-Order Surface Anisotropy Terms in (Ga,Mn)As Thin Films
Autorzy:
Puszkarski, H.
Tomczak, P.
Diep, H.
Powiązania:
https://bibliotekanauki.pl/articles/1030424.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
76.50.+g
75.70.-i
75.30.Ds
76.60.-k
Opis:
We extend the theory of spin-wave resonance (SWR) by introducing a new formula representing the surface pinning parameter as a series of contributions from different anisotropies existing in (Ga,Mn)As thin films. Comparing our theory with the reported experimental studies of SWR in thin films of the ferromagnetic semiconductor (Ga,Mn)As, we find that besides the first-order cubic anisotropy, higher-order cubic anisotropies (in the second and third orders) as well as uniaxial anisotropies (perpendicular in the first and second orders, and in-plane diagonal) occur on the surface of this material. To our best knowledge this is the first report of the existence of higher-order surface anisotropy fields in (Ga,Mn)As thin films.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 635-638
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 44

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