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1

CVD Growth of Graphene Stacks on 4H-SiC (0001) Surface - X-ray Diffraction and Raman Spectroscopy Study

100%

Tokarczyk M., Kowalski G., Grodecki K., Urban J., Strupiński W.

Acta Physica Polonica A

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2013

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vol. 124

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issue 5

768-771

EN

Features associated with short and prolonged growth time in the chemical vapor deposition process of growth of graphene stacks on SiC (0001) substrate are reported. In particular general bimodal (as far as d_{002} interlayer spacing is concerned) distribution of graphene species across the surface of the samples is observed. It consists of thin few layer graphene coverage of most of the sample surface accompanied by thick graphite-like island distribution. It points to the two independent channels of graphene stacks growth with two characteristic growth rates.

2

Superconductivity Study of GaN Highly Doped by Transition Metals

100%

Gosk J., Boćkowski M., Tokarczyk M., Kowalski G., Twardowski A.

Acta Physica Polonica A

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2013

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vol. 124

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issue 5

877-880

EN

GaN:Cr and GaN:Fe single crystals as well as GaN:Mn micropowders highly doped by transition metals were grown to investigate low temperature superconductivity. Magnetic measurements revealed type I superconductivity with T_{C} ≈ 6 K and H_{C} ≈ 600 Oe, identical for all compounds and also identical to that observed before in GaP:Cr and GaAs:Cr. The presence of amorphous inclusions of gallium may explain existing superconductivity as a result of a phase transition leading to β-Ga during cooling down of the sample. Since the observed parameters are close to those characteristic for superconducting Ga(II) this possibility could not be ruled out.

3

Structural and Electronic Properties of Graphene Oxide and Reduced Graphene Oxide Papers Prepared by High Pressure and High Temperature Treatment

73%

Tokarczyk M., Kowalski G., Witowski A., Koziński R., Librant K., Aksienionek M., Lipińska L., Ciepielewski P.

Acta Physica Polonica A

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2014

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vol. 126

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issue 5

1190-1194

EN

"Graphene paper" prepared by new proprietary method involving high pressure and high temperature treatment in the reduction process show new possibilities in this area. Different phase content: multilayer and single layer graphene stacks recorded in this study for RGO samples are accompanied by the specific electric and optical parameters. We have found that process temperatures above 900°C play crucial role in structural and other properties. For the process temperature around 2000°C we found the onset of the graphitization in the samples.

4

1-Methylnicotinamide and nicotinamide: two related anti-inflammatory agents that differentially affect the functions of activated macrophages

73%

Biedron R., Ciszek M., Tokarczyk M., Bobek M., Kurnyta M., Slominska E. M., Smolenski R. T., Marcinkiewicz J.

Archivum Immunologiae et Therapiae Experimentalis

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2008

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vol. 56

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issue 2

127-134

EN

1-Methylnicotinamide (MNA), a major metabolite of nicotinamide (NA), is known to exert anti-inflammatory effects in vivo. Treatment of inflammatory skin diseases by topical application of MNA provides certain advantages over the use of NA. However, in contrast to NA, the molecular mechanisms of the anti-inflammatory properties of MNA are not well known. In this study the influence of exogenous MNA and NA in vitro on the generation of inflammatory mediators by macrophages (Mo) was investigated. Materials and Methods: Peritoneal Mo of CBA/J mice were activated in vitro with lipopolysaccharide and incubated with MNA or NA. The effect of these compounds on biological functions of Mo was measured by evaluation of the production of reactive oxygen species (ROS) by luminol-dependent chemiluminescence, cytokines and prostaglandin E2 (PGE2) by ELISA, and nitric oxide (NO) by the Griess method. Moreover, the expressions of inducible NO synthase and cyclooxygenase-2 were measured by Western blotting. Results: It was shown that at non-cytotoxic concentrations, NA inhibits the production of a variety of pro-inflammatory agents, such as tumor necrosis factor alpha interleukin 6, NO, PGE2, and the generation of ROS. In contrast to NA, exogenous MNA inhibited only the generation of ROS, while its effect on the synthesis of other mediators was negligible. Conclusions: These results indicate that the anti-inflammatory properties of MNA demonstrated previously in vivo do not depend on its capacity to suppress the functions of immune cells, but more likely may be related to its action on vascular endothelium. The authors suggest that the limited permeability for exogenous MNA, in contrast to that for NA, may be responsible for its lack of suppressor activity against Mo.

5

Magnetic Properties of Epitaxial Fe/(Ga,Mn)As Hybrids

59%

Kalbarczyk K., Dziatkowski K., Szczytko J., Gosk J., Tokarczyk M., Kowalski G., Twardowski A., Bednarski W., Ostrowski A., Waplak S., Martinek J., Liu X., Furdyna J.

Acta Physica Polonica A

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2013

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vol. 124

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issue 5

873-876

EN

Thin-film structures composed of two kinds of ferromagnetic material - metallic Fe and semiconducting (Ga,Mn)As - were investigated by means of SQUID magnetometry and ferromagnetic resonance spectroscopy. Dependence of remnant magnetic moment on temperature showed unexpected anisotropic features when recorded along two orthogonal in-plane directions. For one of these orientations, the change in sign of the slope of m(T) curve at the Curie point of (Ga,Mn)As was observed, while for the other, an analogous m(T) curve retained monotonic character. Based on the comparison with ferromagnetic resonance data, the apparent non-monotonicity was attributed to the temperature-induced change of balance between the external magnetic field and uniaxial magnetic anisotropy in the plane of Fe layer.

Refine search results

CVD Growth of Graphene Stacks on 4H-SiC (0001) Surface - X-ray Diffraction and Raman Spectroscopy Study

Superconductivity Study of GaN Highly Doped by Transition Metals

Structural and Electronic Properties of Graphene Oxide and Reduced Graphene Oxide Papers Prepared by High Pressure and High Temperature Treatment

1-Methylnicotinamide and nicotinamide: two related anti-inflammatory agents that differentially affect the functions of activated macrophages

Magnetic Properties of Epitaxial Fe/(Ga,Mn)As Hybrids