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Wyszukujesz frazę "Kellner, K." wg kryterium: Autor


Wyświetlanie 1-6 z 6
Tytuł:
Influence of a heavy-metal-polluted environment on Viola tricolor genome size and chromosome number
Autorzy:
Slomka, A.
Siwinska, D.
Wolny, E.
Kellner, K.
Kuta, E.
Powiązania:
https://bibliotekanauki.pl/articles/19133.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
heavy metal
polluted environment
environment pollution
Viola tricolor
genome size
chromosome number
aneuploidy
polyploidy
pseudometallophyte
Opis:
Intraspecific changes in genome size and chromosome number lead to divergence and species evolution. Heavy metals disturb the cell cycle and cause mutations. Areas contaminated by heavy metals (metalliferous sites) are places where microevolutionary processes accelerate; very often only a few generations are enough for a new genotype to arise. This study, which continues our long-term research on Viola tricolor (Violaceae), a species occurring on both metalliferous (Zn, Pb, Cd, Cu) and non-metalliferous soils in Western and Central Europe, is aimed at determining the influence of environments polluted with heavy metals on genome size and karyological variability. The genome size of V. tricolor ranged from 3.801 to 4.203 pg, but the differences between metallicolous and non-metallicolous populations were not statistically significant. Altered chromosome numbers were significantly more frequent in material from the polluted sites than from the non-polluted sites (43% versus 28%). Besides the standard chromosome number (2n = 26), aneuploid cells with lower (2n = 18–25) or higher (2n = 27, 28) chromosome numbers were found in plants from both types of site, but polyploid (2n = 42) cells were observed only in plants from the metalliferous locality. The lack of correlation between chromosome variability in root meristematic cells and genome size estimated from peduncle cells can be attributed to elimination of somatic mutations in generative meristem, producing chromosome-stable non-meristematic tissues in the peduncle.
Źródło:
Acta Biologica Cracoviensia. Series Botanica; 2011, 53, 1
0001-5296
Pojawia się w:
Acta Biologica Cracoviensia. Series Botanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Was reduced pollen viability in Viola tricolor L. the result of heavy metal pollution or rather the tests applied?
Autorzy:
Slomka, A
Kawalec, P.
Kellner, K.
Jedrzejczyk-Korycinska, M.
Rostanski, A.
Kuta, E.
Powiązania:
https://bibliotekanauki.pl/articles/19806.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Opis:
We used different tests to assess the effect of high soil concentrations of heavy metals on pollen viability in plants from metallicolous (MET) and nonmetallicolous (NONMET) populations. The frequency of viable pollen depended on the test applied: MET plants showed no significant reduction of pollen viability by acetocarmine, Alexander, MTT and X-Gal dye testing, but a drastic reduction of pollen viability in MET flowers (MET 56% vs 72% NONMET) by the FDA test. There was no correlation between pollen viability estimated in histochemical tests and pollen germination in vitro or in vivo. We discuss the terminology used to describe pollen viability as determined by histochemical tests.
Źródło:
Acta Biologica Cracoviensia. Series Botanica; 2010, 52, 1; 123-127
0001-5296
Pojawia się w:
Acta Biologica Cracoviensia. Series Botanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic and Transport Properties of $La_{0.67}Pb_{0.33}(Mn_{1-x}Co_x)O_3$
Autorzy:
Mihalik, M.
Kavečanský, V.
Maťaš, S.
Zentková, M.
Ammer, J.
Kellner, K.
Gritzner, G.
Powiązania:
https://bibliotekanauki.pl/articles/1813631.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.30.+h
72.80.Ga
75.20.Hr
75.30.Et
75.30.Vn
Opis:
Detailed studies of temperature dependences of magnetization, AC susceptibility and electrical resistance were performed on $La_{0.67}Pb_{0.33}(Mn_{1-x}Co_x)O_3$ ceramics with x = 0.01 and 0.1. Typical features of both compounds are the hysteretic behavior between the zero-field-cooled magnetization regime and the field-cooled magnetization regime, a very weak field dependence of a maximum in zero-field-cooled magnetization and practically no frequency dependence of the peak in AC susceptibility χ"(T). Anomalies in the electrical resistance connected with the ferromagnetic transition at $T_C$, the insulator-metal transitions at $T_p$ and the re-entrant metal-isolator transition at T* are field dependent pointing to magnetic origin of these transitions. Colossal magnetoresistance was observed in both compounds.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 251-254
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin and lattice dynamics of La2/3Ca1/3MnO3 doped with 1% 119Sn
Autorzy:
Przewoźnik, J.
Żukrowski, J.
Chmist, J.
Japa, E.
Kołodziejczyk, A.
Krop, K.
Kellner, K.
Gritzner, G.
Powiązania:
https://bibliotekanauki.pl/articles/147199.pdf
Data publikacji:
2004
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
119Sn Mössbauer
LCMO manganites
f-factor
metal-insulator
Opis:
1 at.% 119Sn doped La0.67Ca0.33MnO3 compound was studied by Mössbauer spectroscopy, magnetization, AC susceptibility and resistivity measurements. Huge separation (66 K) of the transition temperatures from the ferromagnetic (FM) to paramagnetic (PM) state (TC) and from metallic to insulating state (TM-I) clearly shows that transition from FM metallic to PM insulator phase goes via FM insulator phase. The Mn lattice dynamics was studied by the relative changes of Lamb-Mössbauer factor f as a function of temperature. In the Debye approximation from the calculated ln(f/f0) values of the characteristic Debye temperatures (čD) were estimated for the FM (368(10) K) and PM (391(6) K) phases. No anomaly of -ln(f/f0) at TM-I and its rather spurious increase around TC was found. The 119Sn isotope as a local diamagnetic probe samples the transferred hyperfine field (Bhf) from its neighbour Mn magnetic moments and witnesses the dynamics of the Mn moments. Theoretical curve based on the molecular field theory was fitted to the experimental values of Bm hf ax and the value of the ordering temperature (TC * H 280 K) of Mn moments inside the large FM domains was estimated. It is much higher than the TC (172 K) obtained from magnetization measurement. The coexistence of FM and PM phases, which is evident from the shape of our 119Sn Mössbauer spectra, was confirmed for temperatures T e 150 K and indicates the inhomogeneous character of the magnetic transition.
Źródło:
Nukleonika; 2004, 49,suppl.3; 37-42
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural, Thermal, Magnetic, and Transport Properties of (La$\text{}_{2}\text{}_{/}\text{}_{3}$ Ca$\text{}_{1}\text{}_{/}\text{}_{3}$ )(Mn$\text{}_{1-x}$Sn$\text{}_{x}$)O$\text{}_{3-δ}$ Compounds
Autorzy:
Przewoźnik, J.
Chmist, J.
Kolwicz-Chodak, L.
Tarnawski, Z.
Kołodziejczyk, A.
Krop, K.
Kellner, K.
Gritzner, G.
Powiązania:
https://bibliotekanauki.pl/articles/2038395.pdf
Data publikacji:
2004-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.47.Lx
75.47.Gk
75.40.Cx
Opis:
The structural, magnetic, and electrical transport properties of Sn-doped manganite La$\text{}_{0.67}$Ca$\text{}_{0.33}$Mn$\text{}_{1-x}$ Sn$\text{}_{x}$O$\text{}_{3-δ}$ (x=0, 0.01, 0.03, andδ≈0.06) compounds were studied using X-ray powder diffraction, scanning electron microscopy, AC susceptometer and vibrating sample magnetometer measurements as well as four-probe resistance measurements. The specific heat was measured by the heat-pulse method. The Curie temperature T$\text{}_{C}$ and the metal-insulator transition temperature T$\text{}_{M-I}$ decreased nonlinearly with increasing Sn content. The T$\text{}_{C}$ and T$\text{}_{M-I}$ values, for the x=0, 0.01, and 0.03 compounds were separated by 18.2 K, 66.3 K, and 10 K, respectively. The resistivity above T$\text{}_{C}$ for all of these compounds followed the Mott variable-range-hopping model. This allowed the estimation of the localization lengths of 2.2Å (x = 0), 1.33Å (x=0.01) and 1.26Å (x=0.03). The x=0 and x=0.01 compounds exhibited anomalies of R(T) at corresponding T$\text{}_{C}$ and allowed the separation of the magnitude of the purely magnetic contribution to the resistance which for x=0 was≈5 .7Ω and for x=0.01,≈22 .4Ω. The specific heat of the Sn-free sample exhibited a sharp peak at T$\text{}_{C}$. With increasing Sn content the peak at T$\text{}_{C}$ broadened and the area under the peak decreased. For x= 0.03 the peak was hardly detectable. Our results on La$\text{}_{0.67}$Ca$\text{}_{0.33}$ Mn$\text{}_{1-x}$Sn$\text{}_{x}$O$\text{}_{3}$ reveal that a small substitution of Sn$\text{}^{4+}$ for Mn$\text{}^{4+}$ suppresses double exchange interactions and strongly affects the magnetic, thermal, and transport properties of the parent compound.
Źródło:
Acta Physica Polonica A; 2004, 106, 5; 665-680
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
SQUID Magnetometry and Magneto-Optics of Epitaxial EuSe
Autorzy:
Rumpf, K.
Granitzer, P.
Kellner, W.
Kirchschlager, R.
Janecek, S.
Pascher, H.
Krenn, H.
Powiązania:
https://bibliotekanauki.pl/articles/2038138.pdf
Data publikacji:
2004-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
78.20.Ls
07.55.Jg
Opis:
The complicated (H,T)-magnetic phase diagram of EuSe is caused by the critical balance between nearest and next nearest neighbour exchange interaction (J$\text{}_{NN}$=0.119 K and J$\text{}_{NNN}$=-0.1209 K) and leads to various spin arrangements NNSS..., NSN..., NNS, NNN... [NS denotes opposite ferromagnetic order in adjacent (111) planes]. Beside the subtle local exchange of 5d-t$\text{}_{2g}$ electrons and localized holes with neighbouring Eu-4f spins, obviously also the strain status influences the occurrence of these different phases. We investigate the magnetic ordering phenomenon in a strained 2.5 μm EuSe film on BaF$\text{}_{2}$ substrate by SQUID magnetometry and magneto-optics like spectral Faraday- and Kerr-effect measurements for temperatures from 2 K up to 200 K and for magnetic fields up to 5 T. The magneto-optical probe monitors the local environment of the photoexcited electron-hole pair, called magnetic exciton, located within a ferromagnetic surrounding (photoinduced magnetic polaron), whereas the integral magnetization measured by SQUID is most sensitive to long-range magnetic ordering. In spite of the dissimilarity of measurement techniques we find an influence of the long-range magnetic order (e.g. of the NNS- or NNN-matrix) on the non-resonant Kerr reflection. The complementarity of SQUID and magneto-optical methods is stringent only in the (resonant) spectral regime, where magnetic polarons are formed.
Źródło:
Acta Physica Polonica A; 2004, 105, 6; 621-629
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-6 z 6

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