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Wyszukujesz frazę "spin-lattice relaxation" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
Splenic eumelanin differs from hair eumelanin in C57BL/6 mice.
Autorzy:
Plonka, Przemyslaw
Michalczyk, Dominika
Popik, Malgorzata
Handjiski, Bori
Slominski, Andrzej
Paus, Ralf
Powiązania:
https://bibliotekanauki.pl/articles/1041424.pdf
Data publikacji:
2005
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
melanin degradation
spin-lattice relaxation
pigmentation
hair cycle
hair follicle
EPR
Opis:
The presence of melanin in spleens of black C57BL/6 mice has been known for long. Although its origin and biological functions are still obscure, the relation of splenic melanin to the hair follicle and skin pigmentation was suggested. Here, we demonstrated using for the first time electron paramagnetic resonance spectroscopy that black-spotted C57BL/6 spleens contain eumelanin. Its presence here is a "yes or no" phenomenon, as even in the groups which revealed the highest percentage of spots single organs completely devoid of the pigment were found. Percentage of the spotted spleens decreased, however, with the progress of telogen after spontaneously-induced hair growth. The paramagnetic properties of the spleen eumelanin differed from the hair shaft or anagen VI skin melanin. The splenic melanin revealed narrower signal, and its microwave power saturability betrayed more heterogenous population of paramagnetic centres than in the skin or hair shaft pigment. Interestingly, the pigment of dry hair shafts and of the wet tissue of depilated anagen VI skin revealed almost identical properties. The properties of splenic melanin better resembled the synthetic dopa melanin (water suspension, and to a lesser degree - powder sample) than the skin/hair melanin. All these findings may indicate a limited degradation of splenic melanin as compared to the skin/hair pigment. The splenic eumelanin may at least in part originate from the skin melanin phagocyted in catagen by the Langerhans cells or macrophages and transported to the organ.
Źródło:
Acta Biochimica Polonica; 2005, 52, 2; 433-441
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Asymmetry in Mössbauer spectra of FeIII-azaporphyrin complexes
Autorzy:
Kaczmarzyk, T.
Jackowski, T.
Dziliński, K.
Sinyakov, G.
Powiązania:
https://bibliotekanauki.pl/articles/148331.pdf
Data publikacji:
2007
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
Mössbauer spectroscopy
iron porphyrins
azaporphyrins
asymmetry in Mössbauer spectra
spin-spin and spin-lattice relaxation
Opis:
Temperature dependence of asymmetry as well as isomer shift and quadrupole splitting values of Mössbauer spectra of trivalent iron complexes coordinated to porphyrin ligands such as octaethylporphyrin, monoazaethioporphyrin, diazaoctaethylporphyrin and phthalacyanine is discussed in this paper. All the above mentioned complexes have the chloride axial ligand at the fifth coordination site. Different temperature changes of asymmetry and other parameters of Mössbauer spectra of these complexes can be correlated with a number of methine bridges CH substituted by nitrogen atoms in the porphyrin macrocycle. The form of this asymmetry is such that the higher-energy component of the doublet is more broadened than the lower-energy one, while the areas (intensities) under each of two components are the same. The most distinct asymmetry is observed at room temperature. When temperature is decreasing, the spectrum becomes successively more symmetrical and at liquid helium temperature linewidths of both components of the quadrupole splitting are very close one another. The Mössbauer spectrum of the FeCl-monoazaethioporphyrin complex exhibits reversed asymmetry at liquid helium temperature in comparison with the spectra of the remaining complexes i.e. the lower-energy component of the doublet is slightly more broadened than the higher-energy one. The spin-spin and spinlattice relaxation mechanisms in the context of quantum mechanically mixed spin states S = 5/2 + 3/2 of FeIII ions are considered as a source of the observed asymmetry.
Źródło:
Nukleonika; 2007, 52, supl. 1; 93-98
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Disturbing effect of different dental materials on the MRI results : preliminary study
Autorzy:
Burchardt, D. V.
Borysewicz-Lewicka, M.
Powiązania:
https://bibliotekanauki.pl/articles/306511.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
dental materials
MRI
spin-lattice
relaxation time T
materiały stomatologiczne
Opis:
The influence of different dental materials used for conserving reconstruction of teeth on the magnetic resonance imaging assessed on the basis of changes in NMR proton relaxation T1 of the physiological environment represented by the physiological salt solution has been studied. The dental materials studied varied in a wide range of chemical compositions: composites (Silux Plus made by 3M Dental, Tetric Cream made by Ivoclar-Vivadent), pH controlling composite (Ariston pHc made by Vivadent), hybrid glass ionomer (Vitremer made by 3M Dental), compomer (Hytac made by ESPE), amalgamate without the gamma phase (Septalloy made by Septodont), chemocured phosphate cement (Agatos made by Chema-Elektromet), phosphate cement with addition of silver (Argil made by Spora-Dental). The reference standard was a 0.9% physiological solution of NaCl. The relative deviations of the spin-lattice relaxation time vary from –18.5% to +24.0%. From the point of view of magnetic resonance imaging, the materials significantly disturbing the tomographic images are the amalgamate Septalloy-Septodont and glass ionomer Vitremer-3M Dental, while the composite Tetric Cream-Vivadent has insignificant effect.
Źródło:
Acta of Bioengineering and Biomechanics; 2013, 15, 4; 49-55
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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