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Nanoscale ; 7(7): 3002-15, 2015 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-25600147


The intimate relationship between stoichiometry and physicochemical properties in transition-metal oxides makes them appealing as tunable materials. These features become exacerbated when dealing with nanostructures. However, due to the complexity of nanoscale materials, establishing a distinct relationship between structure-morphology and functionalities is often complicated. In this regard, in the FexO/Fe3O4 system a largely unexplained broad dispersion of magnetic properties has been observed. Here we show, thanks to a comprehensive multi-technique approach, a clear correlation between the magneto-structural properties in large (45 nm) and small (9 nm) FexO/Fe3O4 core/shell nanoparticles that can explain the spread of magnetic behaviors. The results reveal that while the FexO core in the large nanoparticles is antiferromagnetic and has bulk-like stoichiometry and unit-cell parameters, the FexO core in the small particles is highly non-stoichiometric and strained, displaying no significant antiferromagnetism. These results highlight the importance of ample characterization to fully understand the properties of nanostructured metal oxides.

Mikrobiologiia ; 75(6): 807-13, 2006.
Artigo em Russo | MEDLINE | ID: mdl-17205806


Tundra, chernozem (virgin and arable), sod-podzolic (coniferous forest, meadow, and arable), and grey forest (larch forest) soils were used to separate the contributions of fungi and bacteria to substrate-induced respiration (SIR) with the help of antibiotics. For soils with a high content of organic matter (tundra and chernozem: 12 and 8%, respectively), the procedure of selective inhibition of SIR has been optimized. The optimized procedure includes the application of high concentrations of streptomycin (50-120 mg/g of soil) and cycloheximide (50-80 mg/g of soil) and decreasing the weight of the analyzed soil sample. Soils under study have shown the predominant contribution of fungi (63-82%) to the total SIR. The fungal-bacterial ratio in the soils of natural ecosystems (0-5 cm, without litter) was 4.32, 2.19, 1.5, and 1.5 for tundra soil, virgin chernozem, coniferous (sod-podzolic soil), and larch (grey forest soil) forests, respectively. The lower layers of sod-podzolic (5-10 cm) and grey forest (48-58 cm) soils showed a decrease in the fungal and increase in the bacterial component in the total SIR.

Bactérias , Biomassa , Ecossistema , Fungos , Microbiologia do Solo , Antibacterianos/metabolismo , Solo/análise
Vestn Khir Im I I Grek ; 164(2): 70-2, 2005.
Artigo em Russo | MEDLINE | ID: mdl-16082841


The authors made an analysis of their experiences with treatment of 52 patients. The algorithm of examinations and treatment depending on the character of the injury of the esophagus and stomach is described. Positive results were obtained in 90% of the patients.

Queimaduras/complicações , Constrição Patológica/etiologia , Constrição Patológica/cirurgia , Procedimentos Cirúrgicos do Sistema Digestório/métodos , Estenose Esofágica/etiologia , Estenose Esofágica/cirurgia , Gastropatias/etiologia , Gastropatias/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Constrição Patológica/epidemiologia , Estenose Esofágica/epidemiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Gastropatias/epidemiologia
Phys Rev Lett ; 93(5): 055502, 2004 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-15323705


Simple diatomic molecules exhibit a variety of exciting physical phenomena under high pressures, including structural transitions, pressure induced metallization, and superconductivity. Oxygen is of particular interest because it carries a magnetic moment. For the first time we studied the magnetic structure in solid oxygen under very high pressure by a direct method, namely, neutron diffraction. A new type of magnetic order with ferromagnetic stacking of the antiferromagnetic O2 planes was discovered in delta-O2 at P=6.2 GPa. We show that all structural transformations at pressures <7 GPa are driven by spin interactions; therefore, high-pressure oxygen should be considered as a unique "spin-controlled crystal."