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Hrubovcak P.,Park University | Zelenakova A.,Park University | Zelenak V.,Pj Afarik University | Kovac J.,Slovak Academy of Sciences
Acta Physica Polonica A | Year: 2014

In this work we present the study on structural and magnetic properties of fine cobalt nanoparticles coated by protective gold layer synthetized by microemulsion method. Structural measurements (powder XRD, HRTEM) confirmed spherical shape of the particles, their nanocrystalline character and presence of individual Co and Au phases. Investigation of magnetic properties of the particles revealed superparamagnetic behavior at higher temperatures and magnetic hysteresis at low temperatures. Average magnetic moment of individual particle mp ∼ 86:3μB was established. The critical temperature, below which the magnetic moments of the particles are blocked, was TB = 6 K. Investigation of magnetic relaxation processes via magnetic susceptibility, detected one maximum attributed to single relaxation process, present in the particles. Obtained data, interpreted in terms of Neél-Arrhenius and Vogel-Fulcher theoretical models, confirmed the presence of strong magnetic interparticle interactions. Source


Zvyagin S.A.,Helmholtz Center Dresden | Aimar E.,Pj Afarik University | Ozerov M.,Helmholtz Center Dresden | Wosnitza J.,Helmholtz Center Dresden | And 5 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

Magnetic excitations in copper pyrimidine dinitrate, a spin-1/2 antiferromagnetic chain with alternating g-tensor and Dzyaloshinskii-Moriya interactions that exhibits a field-induced spin gap, are probed by means of pulsed-field electron-spin-resonance spectroscopy. In particular, we report on a minimum of the gap in the vicinity of the saturation field Hsat=48.5 T associated with a transition from the sine-Gordon region (with soliton-breather elementary excitations) to a spin-polarized state (with magnon excitations). This interpretation is fully confirmed by the quantitative agreement over the entire field range of the experimental data with the density matrix renormalization group calculations for a spin-1/2 Heisenberg chain with a staggered transverse field. © 2011 American Physical Society. Source


Varga J.,Pj Afarik University | Varga J.,East Slovakia Oncology Institute | Toth S.,Pj Afarik University | Stasko P.,Pj Afarik University | And 4 more authors.
European Surgical Research | Year: 2011

Decreasing ischemia-reperfusion injury in intestinal transplantation is of paramount importance for improving graft recovery and function. This study explores the ability of two ischemic preconditioning (IPC) regimens to reduce preservation injury. Sprague-Dawley rats were divided into 3 groups (n = 11 each). In the controls (group C), intestinal grafts were harvested and preserved. IPC was performed either through 4 cycles of mesenteric ischemia of 4 min each followed by 10 min of reperfusion (group BIPC) or 2 ischemic cycles of 12 min each followed by 10 min of reperfusion (group LIPC). Grafts were stored in histidine-tryptophan-ketoglutarate, and samples were taken 0, 3, 6, 9, 12, 18, and 24 h after preservation. Preservation injury was scored using the Park/Chiu scale. Goblet cells (GC), enteroendocrine cells (EEC) and serotonin-producing EEC (SPEEC) were studied for evaluation of the graft conditions. Group C had the most advanced preservation injury followed by group BIPC. GC count was lowest in group C, followed by BIPC. Comparison between groups BIPC and LIPC showed superior parameters (preservation injury, GC, EEC, and SPEEC) in LIPC. In conclusion, an IPC regimen of 2 ischemic cycles of 12 min each followed by 10 min of reperfusion distinctly decreased the preservation injury of intestinal grafts compared with non-manipulated grafts. Copyright © 2011 S. Karger AG, Basel. Source


Potocak I.,Pj Afarik University | Imrich J.,Pj Afarik University | Danihel I.,Pj Afarik University | Koisek J.,Slovak University of Technology in Bratislava | Klika K.D.,University of Turku
Acta Crystallographica Section C: Crystal Structure Communications | Year: 2010

Two methyl derivatives, five-membered methyl 2-{2-[2-(9,10-dihydro-acridin- 9-yl-idene)-1-methyl-hydrazin-yl]-4-oxo-4,5-dihydro-1,3-thia-zol-5-yl-idene} acetate, C20H16N4O3S, (I), and six-membered 2-[2-(9,10-dihydro-acridin-9-yl-idene)-1-methyl-hydrazin-yl]-4H-1, 3-thia-zin-4-one, C18H14N4OS, (II), were pre-pared by the reaction of the N-methyl derivative of 4-(9,10-dihydro-acridin- 9-yl-idene)thio-semicarbazide, C14H12N4S, (III), with dimethyl acetyl-enedicarboxyl-ate and methyl propiolate, respectively. The crystal structures of (I), (II) and (III) are mol-ecular and can be considered in two parts: (i) the nearly planar acridine moiety and (ii) the singular heterocyclic ring portion [thia-zolidine for (I) and thia-zine for (II)] including the linking amine and imine N atoms and the methyl C atom, or the full side chain in the case of (III). The structures of (I) and (II) are stabilized by N-H⋯O hydrogen bonds and different π-π inter-actions between acridine moieties and thia-zolidine and thia-zine rings, respectively. © 2010 International Union of Crystallography. Source

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