The Experts below are selected from a list of 145989 Experts worldwide ranked by ideXlab platform
Miran Mozetic - One of the best experts on this subject based on the ideXlab platform.
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Microwave discharge as a remote source of neutral Oxygen Atoms
AIP Advances, 2011Co-Authors: Gregor Primc, Rok Zaplotnik, Alenka Vesel, Miran MozeticAbstract:The late flowing afterglow of an Oxygen plasma was used as a remote source of neutral Oxygen Atoms. Plasma was created via a microwave discharge in a narrow quartz glass tube with an inner diameter of 6 mm at powers between 50 W and 300 W. The tube was connected to a wider perpendicular tube with an inner diameter of 36 mm. The density of neutral Oxygen Atoms was measured in the wide tube about 70 cm from the discharge using a classical nickel catalytic probe. The Oxygen atom density as a function of gas pressure had a well-defined maximum. The Oxygen atom density can be as large as 11 × 1020 m-3. At the lowest power tested (50 W), the maximum was obtained at a pressure of about 30 Pa. However, at higher powers, the maximum shifted to higher pressures. As a result, at 300 W the maximum appeared at 60 Pa. The results can be explained through collision phenomena in gas phase and surfaces in both discharge and flowing afterglow regions, and strong pressure gradients along the narrow tube.
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degradation of staphylococcus aureus bacteria by neutral Oxygen Atoms
Journal of Applied Physics, 2009Co-Authors: Uros Cvelbar, Miran Mozetic, Nina Hauptman, M KlanjsekgundeAbstract:The degradation of Staphylococcus aureus bacteria during treatment with neutral Oxygen Atoms was monitored by scanning electron microscopy. Experiments were performed in an afterglow chamber made from borosilicate glass. The source of Oxygen Atoms was remote inductively coupled radiofrequency Oxygen plasma. The density of Atoms at the samples was 8×1020 m−3. The treatment was performed at room temperature. The first effect was the removal of dried capsule. Capsule on exposed parts of bacteria was removed after receiving the dose of 6×1023 at./m2, while the parts of capsule filling the gaps between bacteria were removed after receiving the dose of 2.4×1024 m−2. After removing the capsule, degradation continued as etching of bacterial cell wall. The etching was rather nonuniform as holes with diameter of several 10 nm were observed. The cell wall was removed after receiving the dose of about 7×1024 m−2. The etching probabilities were about 2×10−5 for the capsule and 2×10−6 for the cell wall. The results wer...
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behaviour of Oxygen Atoms near the surface of nanostructured nb2o5
Journal of Physics D, 2007Co-Authors: Uros Cvelbar, Miran MozeticAbstract:Recombination of neutral Oxygen Atoms on oxidized niobium foil was studied. Three sets of samples have been prepared: a set of niobium foils with a film of polycrystalline niobium oxide with a thickness of 40?nm, another one with a film thickness of about 2??m and a set of foils covered with dense bundles of single-crystal Nb2O3 nanowires. All the samples were prepared by oxidation of a pure niobium foil. The samples with a thin oxide film were prepared by exposure of as-received foils to a flux of O-Atoms, the samples with a thick polycrystalline niobium oxide were prepared by baking the foils in air at a temperature of 800??C, while the samples covered with nanowires were prepared by oxidation in a highly reactive Oxygen plasma. The samples were exposed to neutral Oxygen Atoms from a remote Oxygen plasma source. Depending on discharge parameters, the O-atom density in the postglow chamber, as measured with a catalytic probe, was between 5 ? 1020 and 8 ? 1021?m?3. The O-atom density in the chamber without the samples was found rather independent of the probe position. The presence of the samples caused a decrease in the O-atom density. Depending on the distance from the samples, the O-atom density was decreased up to 5 times. The O-atom density also depended on the surface morphology of the samples. The strongest decrease in the O-atom density was observed with the samples covered with dense bundles of nanowires. The results clearly showed that niobium oxide nanowires exhibit excellent catalytic behaviour for neutral radicals and can be used as catalysts of exhaust radicals found in many applications.
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comparison of fiber optics and standard nickel catalytic probes for determination of neutral Oxygen Atoms concentration
Journal of Vacuum Science and Technology, 2002Co-Authors: Igor Poberaj, Miran Mozetic, Dusan BabicAbstract:The density of neutral Oxygen Atoms in a plasma postglow chamber was measured with a standard Ni catalytic probe and a fiber optical catalytic probe. A highly dissociated Oxygen plasma was created in the discharge chamber with an inductively coupled rf generator with a frequency of 27.12 MHz and output power of 200 W. The measurements were performed in the postglow chamber where a movable recombinator for Oxygen Atoms was placed. The recombinator enabled the adjustment of O density independently of discharge parameters. The density of neutral Oxygen Atoms was determined at different pressures and different positions of the recombinator. The O density was between 5×1020 and 2×1021 m−3. The fiber probe expressed excellent repeatability as compared to the standard probe. As long as the temperature of the catalyst was above 100 °C both probes gave similar results. At a lower temperature of the standard probe, however, the optical fiber probe gave more reasonable results. The discrepancy was attributed to the ...
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Recombination of neutral Oxygen Atoms on stainless steel surface
Applied Surface Science, 2000Co-Authors: Anton Zalar, Miran MozeticAbstract:The recombination coefficient of neutral Oxygen Atoms on polycrystalline AISI 304 stainless steel surface was determined experimentally. The source of neutral Oxygen Atoms was an inductively coupled RF Oxygen plasma. The density of Oxygen Atoms was determined with a nickel catalytic probe and was between 3 × 1019 and 2 × 1021 m-3. A virgin stainless steel disc was activated by exposure to atomic Oxygen at the density of 1.5 × 1021 m-3 for 120 s. During the activation, a layer of oxide with the thickness of about 10 nm was formed on the surface. After successful activation, the temperature of the stainless steel disc during exposures to atomic Oxygen was measured at different O density and different pressure in the system. It was found that the recombination coefficient was a constant at the value of 0.70 ± 0.009.
Yasuhiro Iwasawa - One of the best experts on this subject based on the ideXlab platform.
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atom resolved noncontact atomic force microscopic observations of ceo2 111 surfaces with different oxidation states surface structure and behavior of surface Oxygen Atoms
Journal of Physical Chemistry B, 2003Co-Authors: Yoshimichi Namai, Kenichi Fukui, Yasuhiro IwasawaAbstract:Hexagonally arranged surface Oxygen Atoms, Oxygen point defects, and multiple Oxygen defects at Oxygen-terminated CeO2(111) surfaces in different oxidation states were visualized by noncontact atomic force microscopy (NC-AFM). The multiple defects such as line defects and triangular defects were stabilized by a local reconstruction, where edge Oxygen Atoms surrounding the multiple defects were displaced and gave enhanced brightness due to a geometric reason. Successive NC-AFM measurements of the same area of a slightly reduced CeO2(111) surface revealed that hopping of surface Oxygen Atoms faced to metastable multiple defects was thermally activated even at room temperature. In contrast, no hopping was observed either at a point Oxygen vacancy or a line defect that is stabilized by local reconstruction. It was also confirmed from atom-resolved NC-AFM observations that the surface Oxygen defects were easily healed by exposure to O2 gas at room temperature.
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imaging of surface Oxygen Atoms and their defect structures on ceo2 1 1 1 by noncontact atomic force microscopy
Applied Surface Science, 2002Co-Authors: Kenichi Fukui, Yoshimichi Namai, Yasuhiro IwasawaAbstract:Abstract Atomic-scale structures of CeO2(1 1 1) were examined by noncontact atomic force microscopy (NC-AFM). Hexagonally arranged surface Oxygen Atoms at an ideally Oxygen-terminated surface, Oxygen point vacancies, and multiple Oxygen vacancies such as triangular defects and line defects formed depending on different oxidation states of CeO2−x were visualized by NC-AFM. These observations give a new insight to understand the special Oxygen storage capacity with facile oxidation–reduction cycles for CeO2−x relevant to automotive exhaust catalysis.
Hideki Hosoda - One of the best experts on this subject based on the ideXlab platform.
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role of Oxygen Atoms in α martensite of ti 20 at nb alloy
Scripta Materialia, 2016Co-Authors: Masaki Tahara, Tomonari Inamura, Hee Young Kim, Shuichi Miyazaki, Hideki HosodaAbstract:Abstract The role of Oxygen Atoms in the α″ martensite phase was investigated in the Ti-20 at.% Nb alloy by X-ray diffractometry and differential scanning calorimetry. The axial ratio b / a of α″ martensite and reverse martensitic transformation temperature increased with increasing Oxygen content. These results imply that the α″ martensite was stabilized by Oxygen Atoms, owing to the relaxation of the strain field introduced by the Oxygen Atoms.
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Role of Oxygen Atoms in α″ martensite of Ti-20 at.% Nb alloy
Scripta Materialia, 2016Co-Authors: Masaki Tahara, Tomonari Inamura, Hee Young Kim, Shuichi Miyazaki, Hideki HosodaAbstract:Abstract The role of Oxygen Atoms in the α″ martensite phase was investigated in the Ti-20 at.% Nb alloy by X-ray diffractometry and differential scanning calorimetry. The axial ratio b / a of α″ martensite and reverse martensitic transformation temperature increased with increasing Oxygen content. These results imply that the α″ martensite was stabilized by Oxygen Atoms, owing to the relaxation of the strain field introduced by the Oxygen Atoms.
Zhurui Shen - One of the best experts on this subject based on the ideXlab platform.
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covalent fixation of surface Oxygen Atoms on hematite photoanode for enhanced water oxidation
Chemistry of Materials, 2016Co-Authors: Zhurui ShenAbstract:Suppression of surface states is one of the general issues for metal oxide photoanodes in water oxidation. For hematite (α-Fe2O3), the surface states are mainly attributed to Fe3+/Fe2+ redox couples in Oxygen deficient regions (surface Oxygen vacancies). To date, most of the passivation overlayers against surface states are metal oxides. However, Oxygen vacancies are prevalent for most metal oxides. This is because their formation in metal oxides is often thermodynamically favorable. In contrast, the formation of Oxygen vacancies is more energy-consuming when Oxygen Atoms are covalently bonded. On the basis of this understanding, we propose a new strategy to transform the surface of Fe2O3 into amorphous iron phosphate (denoted “Fe-Pi”), where the Oxygen Atoms are “covalently fixed” in phosphate (PO43–). As a result, the Oxygen vacancies are decreased and the surface states are effectively suppressed. The onset potential of corresponding photoanode shifts negatively by 0.15 V and the photocurrent density i...
Junhua Luo - One of the best experts on this subject based on the ideXlab platform.
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phase transition originating from order disorder transformations of carboxy Oxygen Atoms coupled with dynamic proton motions in phch2nh ch3 2 2c2o4 h2c2o4
Chemistry-an Asian Journal, 2014Co-Authors: Yuanyuan Tang, Zhihua Sun, Shuquan Zhang, Tianliang Chen, Junhua LuoAbstract:A new molecular phase transition material, [PhCH(2) NH(CH(3))(2)](2) C(2)O(4)⋅H(2)C(2)O(4), which undergoes a reversible phase transition at 151.6 K, has been successfully synthesized. Differential scanning calorimetry (DSC), specific heat capacity, and dielectric measurements confirm its reversible phase transition with a large thermal hysteresis of 15.1 K, demonstrating that the phase transition is typical first order. Variable-temperature single-crystal X-ray diffraction analyses reveal that the order-disorder transformations of carboxy Oxygen Atoms induce the structural phase transition. A slight reorientation of the oxalic acid unit is discovered to accompany the ordering of carboxy Oxygen Atoms at low temperature. The DSC measurement result of the deuterated analog is different to that of 1, indicating that proton dynamic motions in hydrogen bonds also contribute to the phase transition.
