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Oxygen Deficiency (oxygen + deficiency)
Selected AbstractsDetermination of the Oxygen Deficiency in Vacuum-Hot-Pressed Ferroelectric Ceramics Using a Thermogravimetric TechniqueJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2000Qi Tan An attempt to measure the oxygen deficiency in vacuum-hot-pressed ferroelectric target materials was made, using a thermogravimetric method. The approach was intended to measure the relative mass increase of oxygen-deficient sheet samples, with respect to an oxidized reference that was annealed in air. A saturation of mass change was achieved, which indicated a saturated oxidation state and provided a basis for further calculation of the oxygen deficiency in the samples. Results were obtained for barium strontium titanate and lead lanthanum zirconate titanate compositions, which shows the feasibility of applying the thermogravimetric method to ferroelectric materials. [source] Flow Distribution During Cardiopulmonary Bypass in Dependency on the Outflow Cannula PositioningARTIFICIAL ORGANS, Issue 11 2009Tim A.S. Kaufmann Abstract Oxygen deficiency in the right brain is a common problem during cardiopulmonary bypass (CPB). This is linked to an insufficient perfusion of the carotid and vertebral artery. The flow to these vessels is strongly influenced by the outflow cannula position, which is traditionally located in the ascending aorta. Another approach however is to return blood via the right subclavian artery. A computational fluid dynamics (CFD) study was performed for both methods and validated by particle image velocimetry (PIV). A 3-dimensional computer aided design model of the cardiovascular (CV) system was generated from realtime computed tomography and magnetic resonance imaging data. Mesh generation (CFD) and rapid prototyping (PIV) were used for the further model creation. The simulations were performed assuming usual CPB conditions, and the same boundary conditions were applied for the PIV validation. The flow distribution was analyzed for 55 cannula positions inside the aorta and in relation to the distance between the cannula tip and the vertebral artery branch for subclavian cannulation. The study reveals that the Venturi effect due to the cannula jet appears to be the main reason for the loss in cerebral perfusion seen clinically. It provides a PIV-validated CFD method of analyzing the flow distribution in the CV system and can be transferred to other applications. [source] Heterologous Expression of Vitreoscilla Hemoglobin (VHb) and Cultivation Conditions Affect the Alkaloid Profile of Hyoscyamus muticus Hairy RootsBIOTECHNOLOGY PROGRESS, Issue 2 2006Annika Wilhelmson Fast-growing hairy root cultures of Hyoscyamus muticus induced by Agrobacterium rhizogenes offer a potential production system for tropane alkaloids. Oxygen deficiency has been shown to limit growth and biomass accumulation of hairy roots, whereas little experimental data is available on the effect of oxygen on alkaloid production. We have investigated the effect of Vitreoscilla hemoglobin (VHb) expression and cultivation conditions on the complete alkaloid profile of H. muticus hairy roots in shake flasks and in a laboratory scale bioreactor. We optimized the growth medium composition and studied the effects of sucrose, ammonium, nitrate, and phosphate on growth and alkaloid production. Maximum biomass accumulation was achieved with the highest and maximum hyoscyamine content with the lowest sucrose concentration. The optimum nitrate concentration for growth was higher for the VHb line than the control. Neither VHb expression nor aeration improved the hyoscyamine content significantly, thus suggesting that hyoscyamine biosynthesis is not limited by oxygen availability. Interestingly, the effect of VHb expression on the alkaloid profile was slightly different from that of aeration. VHb expression did not affect the concentrations of cuscohygrine, which was increased by aeration. Therefore, the effect of VHb is probably not related only to its ability to increase the intracellular effective oxygen concentration. [source] Subgap states, doping and defect formation energies in amorphous oxide semiconductor a-InGaZnO4 studied by density functional theoryPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2010Toshio Kamiya Abstract Amorphous In-Ga-Zn-O (a-IGZO) is expected for channel layers in thin-film transistors (TFTs). It is known that a-IGZO is sensitive to an O/H-containing atmosphere; therefore, it is important to clarify the roles of oxygen and hydrogen in a-IGZO. This paper provides atomic and electronic structures, formation energies of defects and bond energies in a-IGZO calculated by first-principles density functional theory (DFT). It was confirmed that oxygen deficiencies having small formation energies (2,3.6,eV) form either deep fully-occupied localized states near the valence band maximum or donor states, which depend on their local structures. All the hydrogen doping form OH bond and work as a donor. The stable OH bonds have small formation energy of ,0.45,eV and consist of three metal cations coordinated to the O ion. The bond energy of GaO is calculated to be ,2.0,eV, which is the largest among the chemical bonds in a-IGZO (1.7,eV for InO and 1.5,eV for ZnO). This result supports the idea that the incorporation of Ga stabilizes a-IGZO TFTs. [source] Anguillicoloides crassus infection of European eel, Anguilla anguilla (L.), in inland waters of Estonia: history of introduction, prevalence and intensityJOURNAL OF APPLIED ICHTHYOLOGY, Issue 2010A. Kangur Summary Eel fishery in Estonian inland waters depends entirely on the stocking of glass eels or pre-grown (farmed) eels. Via importation of live eels of 20,30 cm length the non-indigenous swimbladder nematode Anguillicoloides crassus was probably introduced via Germany into Lake Võrtsjärv in 1988, and has since spread to many inland waters of Estonia. In 1992, the parasite was found in eel caught from Lake Võrtsjärv. Between 1992 and 2002 and additionally in 2008, we examined in total 870 eels from Lake Võrtsjärv (270 km2) and in 2008, 63 eels from three small lakes for adult A. crassus. The aim of the study was to obtain information on the variation of A. crassus infection in eels in Estonian lakes, to determine the temporal dynamics of prevalence and intensity of infection, and to establish a relationship between the length of host and intensity of infection in the eels in Lake Võrtsjärv. There appeared to be a pronounced variation in prevalences of infected eels (from 3.7% to 100%) between the four investigated lakes. However, in Lake Võrtsjärv, the prevalence of adult A. crassus infection remained stable (mean about 65%) for many years. The average number of nematode per infected eel (mean intensity) ranged from 12.6 ± 2.5 in 1993 to 4.0 ± 0.6 in 1999 in Lake Võrtsjärv, while it was significantly higher (P < 0.0001) in the period 1992,1998 compared to 1999,2002 and 2008. The mean number of parasites per swimbladder was not related to eel length and no statistical difference was found in the condition factor of infected and non-infected eels. Although under normal environmental conditions A. crassus has not caused serious disease problems to eels in the study area, high intensity of parasite infection may contribute to eel kills due to oxygen deficiency in winter under the ice in Lake Võrtsjärv. [source] Temperature-dependent changes in energy metabolism, intracellular pH and blood oxygen tension in the Atlantic codJOURNAL OF FISH BIOLOGY, Issue 6 2003F. J. Sartoris The effect of acute increase in temperature on oxygen partial pressure (Po2) was measured in the gill arches of Atlantic cod Gadus morhua between 10 and 19° C by use of oxygen microoptodes. Oxygen saturation of the gill blood under control conditions varied between 90 and 15% reflecting a variable percentage of arterial or venous blood in accordance with the position of each optode in the gill arch. The data obtained suggested that arterial Po2 remained more or less constant and arterial oxygen uptake did not become limiting during warming. A progressive drop in venous Po2, however, was observed at >10° C indicating that excessive oxygen uptake from the blood is not fully compensated for by circulatory performance, until finally, Po2 levels fully collapse. In a second set of experiments energy and acid,base status of white muscle of Atlantic cod in vivo was measured by magnetic resonance (31P-NMR) spectroscopy in unanaesthetized and unimmobilized fish in the temperature range between 13 and 21° C. A decrease in white muscle intracellular pH (pHi) with temperature occurred between 10 and 16° C (,pH per ° C = ,0·025 per ° C). In white muscle temperature changes had no influence on high-energy phosphates such as phosphocreatine (PCr) or ATP except during exposure to high critical temperatures (>16° C), indicating that white muscle energy status appears to be relatively insensitive to thermal stress if compared to the thermal sensitivity of the whole animal. The data were consistent with the hypothesis of an oxygen limitation of thermal tolerance in animals, which is set by limited capacity of oxygen supply mechanisms. In the case of Atlantic cod circulatory rather than ventilatory performance may be the first process to cause oxygen deficiency during heat stress. [source] Determination of the Oxygen Deficiency in Vacuum-Hot-Pressed Ferroelectric Ceramics Using a Thermogravimetric TechniqueJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2000Qi Tan An attempt to measure the oxygen deficiency in vacuum-hot-pressed ferroelectric target materials was made, using a thermogravimetric method. The approach was intended to measure the relative mass increase of oxygen-deficient sheet samples, with respect to an oxidized reference that was annealed in air. A saturation of mass change was achieved, which indicated a saturated oxidation state and provided a basis for further calculation of the oxygen deficiency in the samples. Results were obtained for barium strontium titanate and lead lanthanum zirconate titanate compositions, which shows the feasibility of applying the thermogravimetric method to ferroelectric materials. [source] The Impact of Aortic/Subclavian Outflow Cannulation for Cardiopulmonary Bypass and Cardiac Support: A Computational Fluid Dynamics StudyARTIFICIAL ORGANS, Issue 9 2009Tim A.S. Kaufmann Abstract Approximately 100 000 cases of oxygen deficiency in the brain occur during cardiopulmonary bypass (CPB) procedures each year. In particular, perfusion of the carotid and vertebral arteries is affected. The position of the outflow cannula influences the blood flow to the cardiovascular system and thus end organ perfusion. Traditionally, the cannula returns blood into the ascending aorta. But some surgeons prefer cannulation to the right subclavian artery. A computational fluid dynamics study was initially undertaken for both approaches. The vessel model was created from real computed tomography/magnetic resonance imaging data of young healthy patients. The simulations were run with usual CPB conditions. The flow distribution for different cannula positions in the aorta was studied, as well as the impact of the cannula tip distance to vertebral artery for the subclavian position. The study presents a fast method of analyzing the flow distribution in the cardiovascular system, and can be adapted for other applications such as ventricular assist device support. It revealed that two effects cause the loss of perfusion seen clinically: a vortex under the brachiocephalic trunk and low pressure regions near the cannula jet. The results suggest that cannulation to the subclavian artery is preferred if the cannula tip is sufficiently far away from the branch of the vertebral artery. For the aortic positions, however, the cannula should be injected from the left body side. [source] Evidence of the final drainage of the Baltic Ice Lake and the brackish phase of the Yoldia Sea in glacial varves from the Baltic SeaBOREAS, Issue 3 2002THOMAS ANDRÉN A clay-varve chronology based on 14 cross-correlated varve graphs from the Baltic Sea and a mean varve thickness curve has been constructed. This chronology is correlated with the Swedish Time Scale and covers the time span 11 530 to 10250 varve years BP. Two cores have been analysed for grain size, chemistry, content of diatoms and changes in colour by digital colour analysis. The final drainage of the Baltic Ice Lake is dated to c. 10800 varve years BP and registered in the cores analysed as a decrease in the content of clay. This event can be correlated with atmospheric ,14C content and might have resulted in an increase in these values recorded between 11 565 and 11 545 years BP. The results of the correlation between the varve chronology from the Baltic Sea, the Greenland GRIP ice core and the atmospheric ,14C record indicate that c. 760 years are missing in the Swedish Time Scale in the part younger than c. 10250 varve years BP. A change in colour from a brownish to grey varved glacial clay recorded c. 10770 varve years BP is found to be the result of oxygen deficiency due to an increase in the rate of sedimentation in the early Preboreal. The first brackish influence is recorded c. 10540 varve years BP in the northwestern Baltic Sea and some 90 years later in the eastern Gotland Basin. [source] | ||||||||||