Search results for "oxygen concentration"
showing 10 items of 43 documents
Catalytic performances of Co3O4/CeO2 and Co3O4/CeO2-ZrO2Composite oxides for methane combustion: influence of catalyst pretreatment temperature and o…
2007
Abstract The influence of catalyst pre-treatment temperature (650 and 750 °C) and oxygen concentration ( λ = 8 and 1) on the light-off temperature of methane combustion has been investigated over two composite oxides, Co 3 O 4 /CeO 2 and Co 3 O 4 /CeO 2 –ZrO 2 containing 30 wt.% of Co 3 O 4 . The catalytic materials prepared by the co-precipitation method were calcined at 650 °C for 5 h (fresh samples); a portion of them was further treated at 750 °C for 7 h, in a furnace in static air (aged samples). Tests of methane combustion were carried out on fresh and aged catalysts at two different WHSV values (12 000 and 60 000 mL g −1 h −1 ). The catalytic performance of Co 3 O 4 /CeO 2 and Co 3…
Ein neuartiges Verfahren der Sauerstoffdetektion für Medizin, Biologie, Umweltforschung und Biotechnik auf Basis der Lumineszenzlöschung - An Innovat…
1996
For most (aerobic) animal organisms, oxygen is a mandatory and global substrate. The accurate measurement of oxygen is therefore of importance in the fields of medicine, biology, environmental research and biotechnology. The fact that oxygen is not readily soluble in aqueous media makes its detection more difficult. In contrast to the technique of polarography, the use of luminescence quenching by paramagnetic oxygen, does not consume the oxygen. Another problem of oxygen detection in connection with respiration is the need for very short response times. A third problem, which is associated with luminescence itself, is the fading of the dyes, which results in long-term signal instability. T…
Mechano-activated processes on metal oxide interfaces at room temperature
1997
Solid state bonding of metal with oxide at room temperature have been studied. The properties of Al/SiO 2 , Al/glass, Al/MgO, Mg/SiO 2 , In/glass interfaces as well as to ascertain the mechanism of formation of interfaces. Structure, composition and mechanical properties were investigated using auger-spectroscopy (AES), secondary-ion mass-spectrometry (SIMS), electron microscopy and precision microindentation. The results showed marked adhesion not all over contact area but only at zones of the maximum shear stress. The effect of mechanoactivation is considered from the viewpoints of both structure formation and physico- chemical interaction of nonequilibrium systems. As a result of relaxat…
Interface of Silicon Nitride Nanolayers with Oxygen Deficiency
2018
Multilayer Si 3 N 4 consisting of Si 3 N 4 nanolayers with the total thickness 60 nm was deposited layer-by-layer in a low-pressure chemical vapor deposition process. Compared with the single-layer Si 3 N 4 , the multilayer Si 3 N 4 had one-third less oxygen concentration at the interfaces. This decreased density of electrically active centers of oxygen traps and improved quality of nanocapacitors with multilayer Si 3 N 4 dielectric.
Reduction of temperature coefficients in multicrystalline silicon solar cells after light-induced degradation
2015
This study focuses on the variations of the temperature coefficients after light-induced degradation (LID) of compensated multicrystalline silicon solar cells from three different ingots. The ingots have been chosen to see the effect of the compensation level, the resistivity and the impact of adding gallium to keep the resistivity as constant as possible along the ingot. The temperature coefficients of the efficiency experience a major decrease after LID on all ingots. We found that this decrease varies along the ingot height and does not correspond to the VOC drop. Moreover, no direct correlation with the interstitial oxygen concentration profiles could be seen.
The late Hauterivian Faraoni "Oceanic Anoxic Event" at Río Argos (southern Spain): an assessment on the level of oxygen depletion.
2013
14 pages; International audience; An integrated study of multiple geochemical proxies (TOC, δ13Ccarb, trace metallic elements, iron speciation) on the late Hauterivian Faraoni Oceanic Anoxic Event has been performed along the hemi-pelagic section of Río Argos (south-eastern Spain) in order to better constrain the environmental perturbations linked to this event in the Subbetic domain. In the studied section, the TOC is relatively low (b0.5 wt.%) except for one sample at the base of the Faraoni horizon, where it reaches 1.5 wt.%. The δ13Ccarb signal is characterized by a minor long-term increase, primarily attributed to an enhanced organic matter burial. However, both organic and isotopic si…
OXYGEN SOLUBILITY IN NORMAL HUMAN BLOOD
1981
Publisher Summary This chapter describes oxygen solubility in normal human blood. The most crucial problem in measuring physically dissolved oxygen in blood is the prevention of oxygen binding by hemoglobin (Hb). The chapter discusses a study for the re-determination of oxygen solubility in untreated human blood. The oxygen concentration was measured by a photometric method and the Hb-concentration was determined by the cyanohemoglobin method. Oxygen solubility in normal and untreated blood is a linear function of the Hb-concentration. Hemoglobin in the reduced state has a greater influence on oxygen solubility than hemoglobin. Red cell membranes have no measureable effect on the oxygen sol…
Emissions and spatial variability of N2O, N2 and nitrous oxide mole fraction at the field scale, revealed with 15N isotopic techniques.
2006
Abstract The accurate measurement of nitrous oxide (N 2 O) and dinitrogen (N 2 ) during the denitrification process in soils is a challenge which will help to estimate the contribution of soil N 2 O emissions to global warming. Oxygen concentration, nitrate concentration and carbon availability are generally the main factors that control soil denitrification rate and the amount of N 2 O or N 2 emitted. The aim of this paper is to present a database of the N 2 O mole fraction measured at the field scale, and to test hypotheses concerning its regulation. A 15 N-nitrate tracer solution was added to 36 undisturbed soil cores on a 20 m×20 m cultivated field plot. Fluxes of CO 2 , N 2 O and N 2 f…
Effect of O2 control and monitoring on the nutraceutical properties of extra virgin olive oils
2016
Abstract The presence of oxygen during malaxation has key role in improving Extra Virgin Olive Oil (EVOO) quality in terms of volatile and phenolic compounds. The objective of this study was to evaluate the influence of the head space malaxer oxygen concentration on the physicochemical characteristics and nutraceutical properties of EVOO from the Nocellara del Belice olives. The acidic compounds were related to the concentration of the oxygen presented in the machine headspace considering a new software application for the online oxygen management opportunely designed and applicable to all the existing plants. The right timepoint and oxygen concentration of the malaxation process was establ…
Effect of Mechanoactivation on Interfacial Interaction in Metal/Oxide Systems
2006
Properties of interfaces in solid state metal/oxide joints (Al/SiO2, Al/MgO, Al/glass, Mg/MgO, Mg/SiO2, In/glass etc.) are reported. The interfaces were formed by plastic deformation of metal on the oxide surface at room temperature. Their structure, chemical composition, and micromechanical properties were studied by the AFM, XRD, SIMS, optical microscopy, and precision microindentation techniques. A noticeable adhesion was observed for metals with high affinity for oxygen and only in the regions of the maximum shear stress. Formation of an interfacial reaction zone with an oxygen concentration gradient is detected. In this zone metals are nanostructured and noticeably hardened. The effect…