Photoluminescence due to early stage of oxygen precipitation in multicrystalline Si for solar cells

NASA Astrophysics Data System (ADS)

Higuchi, Fumito; Tajima, Michio; Ogura, Atsushi

2017-07-01

To analyze the early stage of oxygen precipitation in n-type multicrytalline Si, the spectral change of photoluminescence (PL) induced by thermal treatment at 450-650 °C was investigated in relation to the changes in excess donor and interstitial oxygen concentrations. We observed the characteristic PL bands in the near-band-edge region and sharp lines in the deep-level region in correspondence with the generation of thermal donors and new donors. The observed PL spectral variation is essentially the same as that in Czochralski-grown Si annealed at 450-650 °C.

Trace element control in binary Ni-25Cr and ternary Ni-30Co-30Cr master alloy castings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Detrois, Martin; Jablonski, Paul D.

Electro-slag remelting (ESR) is used for control of unwanted elements in commercial alloys. This study focuses on master alloys of Ni-25Cr and Ni-30Co-30Cr, processed through a combination of vacuum induction melting (VIM) and electro-slag remelting (ESR). Minor additions were made to control tramp element levels and modify the melting characteristics. Nitrogen and sulfur levels below 10 ppm and oxygen levels below 100 ppm were obtained in the final products. The role of the alloy additions in lowering the tramp element content, the resulting residual inclusions and the melting characteristics were determined computationally and confirmed experimentally. Additions of titanium were beneficialmore » to the control of oxygen levels during VIM and nitrogen levels during ESR. Aluminum additions helped to control oxygen levels during remelting, however, aluminum pickup occurred when excess titanium was present during ESR. The usefulness of these master alloys for use as experimental remelt stock will also be discussed.« less

Fluid-electrolyte shifts and maximal oxygen uptake in man at simulated altitude /2,287 m/

NASA Technical Reports Server (NTRS)

Greenleaf, J. E.; Bernauer, E. M.; Adams, W. C.; Juhos, L.

1978-01-01

Experiments were conducted on six trained distance runners (21-23 yr) subjected to an eight-day dietary control at sea level, followed by an eight-day stay in an altitude chamber (2287-m altitude) and a four-day recovery at sea level. Fluid and electrolyte shifts during exercise at altitude were evaluated to gain insight into the mechanism of reduction in working capacity. The results are discussed in terms of resting fluid volumes and blood constituents, maximal exercise variables, and maximal exercise fluid-electrolyte shifts. Since there are no significant changes in fluid balance or resting plasma volume (PV) at altitude, it is concluded that neither these nor the excessive PV shifts with exercise contribute to the reduction in maximal oxygen uptake at altitude. During altitude exposure the percent loss in PV is found to follow the percent reduction in maximal oxygen uptake; however, on the first day of recovery the percent change in PV remains depressed while maximal oxygen uptake returns to control levels.

Exploring the nutrient inputs and cycles in Tampa Bay and coastal watersheds using MODIS images and data mining

NASA Astrophysics Data System (ADS)

Chang, Ni-Bin; Xuan, Zhemin

2011-09-01

Excessive nutrients, which may be represented as Total Nitrogen (TN) and Total Phosphorus (TP) levels, in natural water systems have proven to cause high levels of algae production. The process of phytoplankton growth which consumes the excess TN and TP in a water body can also be related to the changing water quality levels, such as Dissolved Oxygen (DO), chlorophyll-a, and turbidity, associated with their changes in absorbance of natural radiation. This paper explores spatiotemporal nutrient patterns in Tampa Bay, Florida with the aid of Moderate Resolution Imaging Spectroradiometer or MODIS images and Genetic Programming (GP) models that are deigned to link those relevant water quality parameters in aquatic environments.

An investigation of excess residual cytoplasm in human spermatozoa and its distinction from the cytoplasmic droplet

PubMed Central

2012-01-01

Recent studies have shown cytoplasmic droplets to be normal morphological occurrences in human male spermatozoa. When the cytoplasm around the sperm midpiece is present in large amounts, however, pathological effects may transpire. The cytoplasmic droplet then becomes known as excess residual cytoplasm, which can impair overall sperm function and produce higher levels of reactive oxygen species, potentially leading to male infertility. Though the distinction between cytoplasmic droplets and excess residual cytoplasm has been made, some studies fail to recognize the difference and incorrectly label the latter as a cytoplasmic droplet. This review attempts to clarify excess residual cytoplasm’s effect on fertility, examine the enzymes responsible, and suggest tests and possible treatment options for those affected by this defect. PMID:23159014

Silver oxysalts promote cutaneous wound healing independent of infection.

PubMed

Thomason, Helen A; Lovett, Jodie M; Spina, Carla J; Stephenson, Christian; McBain, Andrew J; Hardman, Matthew J

2018-03-12

Chronic wounds often exist in a heightened state of inflammation whereby excessive inflammatory cells release high levels of proteases and reactive oxygen species (ROS). While low levels of ROS play a fundamental role in the regulation of normal wound healing, their levels need to be tightly regulated to prevent a hostile wound environment resulting from excessive levels of ROS. Infection amplifies the inflammatory response, augmenting levels of ROS which creates additional tissue damage that supports microbial growth. Antimicrobial dressings are used to combat infection; however, the effects of these dressing on the wound environment and healing independent of infection are rarely assessed. Cytotoxic or adverse effects on healing may exacerbate the hostile wound environment and prolong healing. Here we assessed the effect on healing independent of infection of silver oxysalts which produce higher oxidative states of silver (Ag 2+ /Ag 3+ ). Silver oxysalts had no adverse effect on fibroblast scratch wound closure whilst significantly promoting closure of keratinocyte scratch wounds (34% increase compared with control). Furthermore, dressings containing silver oxysalts accelerated healing of full-thickness incisional wounds in wild-type mice, reducing wound area, promoting reepithelialization, and dampening inflammation. We explored the mechanisms by which silver oxysalts promote healing and found that unlike other silver dressings tested, silver oxysalt dressings catalyze the breakdown of hydrogen peroxide to water and oxygen. In addition, we found that silver oxysalts directly released oxygen when exposed to water. Collectively, these data provide the first indication that silver oxysalts promote healing independent of infection and may regulate oxidative stress within a wound through catalysis of hydrogen peroxide. © 2018 by the Wound Healing Society.

Detection of gaseous oxygen using temperature tuned laser diodes

NASA Technical Reports Server (NTRS)

Fox, Curtis W.; Disimile, Peter J.

1990-01-01

The development of an optical differential absorption technique using laser diodes is discussed. The technique is being developed as a solution to overcome the difficulties imposed by conventional liquid rocket propulsion system leak detection such as damage to the engine, cumbersome equipment, and excessive amounts of time. The detection of O2 at atmospheric pressure and temperature using laser diodes is demonstrated. Also, it is shown that, by temperature tuning the laser diode, the wavelength was shifted to a level where the oxygen absorption peaks are found. The levels of transmission determined via experimental means and those calculated from spectral data are found to be in close agreement.

Mitochondrial Redox Signaling and Tumor Progression.

PubMed

Chen, Yuxin; Zhang, Haiqing; Zhou, Huanjiao Jenny; Ji, Weidong; Min, Wang

2016-03-25

Cancer cell can reprogram their energy production by switching mitochondrial oxidative phosphorylation to glycolysis. However, mitochondria play multiple roles in cancer cells, including redox regulation, reactive oxygen species (ROS) generation, and apoptotic signaling. Moreover, these mitochondrial roles are integrated via multiple interconnected metabolic and redox sensitive pathways. Interestingly, mitochondrial redox proteins biphasically regulate tumor progression depending on cellular ROS levels. Low level of ROS functions as signaling messengers promoting cancer cell proliferation and cancer invasion. However, anti-cancer drug-initiated stress signaling could induce excessive ROS, which is detrimental to cancer cells. Mitochondrial redox proteins could scavenger basal ROS and function as "tumor suppressors" or prevent excessive ROS to act as "tumor promoter". Paradoxically, excessive ROS often also induce DNA mutations and/or promotes tumor metastasis at various stages of cancer progression. Targeting redox-sensitive pathways and transcriptional factors in the appropriate context offers great promise for cancer prevention and therapy. However, the therapeutics should be cancer-type and stage-dependent.

Climate variations and the physiological basis of temperature dependent biogeography: systemic to molecular hierarchy of thermal tolerance in animals.

PubMed

Pörtner, H O

2002-08-01

The physiological mechanisms limiting and adjusting cold and heat tolerance have regained interest in the light of global warming and associated shifts in the geographical distribution of ectothermic animals. Recent comparative studies, largely carried out on marine ectotherms, indicate that the processes and limits of thermal tolerance are linked with the adjustment of aerobic scope and capacity of the whole animal as a crucial step in thermal adaptation on top of parallel adjustments at the molecular or membrane level. In accordance with Shelford's law of tolerance decreasing whole animal aerobic scope characterises the onset of thermal limitation at low and high pejus thresholds (pejus=getting worse). The drop in aerobic scope of an animal indicated by falling oxygen levels in the body fluids and or the progressively limited capacity of circulatory and ventilatory mechanisms. At high temperatures, excessive oxygen demand causes insufficient oxygen levels in the body fluids, whereas at low temperatures the aerobic capacity of mitochondria may become limiting for ventilation and circulation. Further cooling or warming beyond these limits leads to low or high critical threshold temperatures (T(c)) where aerobic scope disappears and transition to an anaerobic mode of mitochondrial metabolism and progressive insufficiency of cellular energy levels occurs. The adjustments of mitochondrial densities and their functional properties appear as a critical process in defining and shifting thermal tolerance windows. The finding of an oxygen limited thermal tolerance owing to loss of aerobic scope is in line with Taylor's and Weibel's concept of symmorphosis, which implies that excess capacity of any component of the oxygen delivery system is avoided. The present study suggests that the capacity of oxygen delivery is set to a level just sufficient to meet maximum oxygen demand between the average highs and lows of environmental temperatures. At more extreme temperatures only time limited passive survival is supported by anaerobic metabolism or the protection of molecular functions by heat shock proteins and antioxidative defence. As a corollary, the first line of thermal sensitivity is due to capacity limitations at a high level of organisational complexity, i.e. the integrated function of the oxygen delivery system, before individual, molecular or membrane functions become disturbed. These interpretations are in line with the more general consideration that, as a result of the high level of complexity of metazoan organisms compared with simple eukaryotes and then prokaryotes, thermal tolerance is reduced in metazoans. A similar sequence of sensitivities prevails within the metazoan organism, with the highest sensitivity at the organismic level and wider tolerance windows at lower levels of complexity. However, the situation is different in that loss in aerobic scope and progressive hypoxia at the organismic level define the onset of thermal limitation which then transfers to lower hierarchical levels and causes cellular and molecular disturbances. Oxygen limitation contributes to oxidative stress and, finally, denaturation or malfunction of molecular repair, e.g. during suspension of protein synthesis. The sequence of thermal tolerance limits turns into a hierarchy, ranging from systemic to cellular to molecular levels.

Inverse correlation between reactive oxygen species in unwashed semen and sperm motion parameters as measured by a computer-assisted semen analyzer.

PubMed

Takeshima, Teppei; Yumura, Yasushi; Yasuda, Kengo; Sanjo, Hiroyuki; Kuroda, Shinnosuke; Yamanaka, Hiroyuki; Iwasaki, Akira

2017-01-01

This study investigated the correlation between sperm motion parameters obtained by a computer-assisted semen analyzer and levels of reactive oxygen species in unwashed semen. In total, 847 patients, except for azoospermic patients were investigated. At the time of each patient's first consultation, semen parameters were measured using SMAS™ or CellSoft 3000™, and production of reactive oxygen species was measured using a computer-driven LKB Wallac Luminometer 1251 Analyzer. The patients were divided into two groups: reactive oxygen species - positive and negative. The semen parameters within each group were measured using one of the two computer-assisted semen analyzer systems and then compared. Correlations between reactive oxygen species levels and sperm motion parameters in semen from the reactive oxygen species - positive group were also investigated. Reactive oxygen species were detected in semen samples of 282 cases (33.3%). Sperm concentration (P < 0.01; P < 0.01), motility (P < 0.01; P < 0.05), and progressive motility (P < 0.01; P < 0.01) were markedly lower in the reactive oxygen species - positive group than in the reactive oxygen species - negative group. Among the sperm motion parameters in the reactive oxygen species - positive group, sperm concentration (P < 0.01; P < 0.01), motility (P < 0.05; P < 0.01), mALH (P < 0.05; P < 0.01), and progressive motility (P < 0.05; P < 0.01) also showed inverse correlations with the logarithmic transformed reactive oxygen species levels. Therefore, this study demonstrated that excessive reactive oxygen species in semen damage sperm concentration, motility, and other sperm motion parameters.

Computational Model for Oxygen Transport and Consumption in Human Vitreous

PubMed Central

Filas, Benjamen A.; Shui, Ying-Bo; Beebe, David C.

2013-01-01

Purpose. Previous studies that measured liquefaction and oxygen content in human vitreous suggested that exposure of the lens to excess oxygen causes nuclear cataracts. Here, we developed a computational model that reproduced available experimental oxygen distributions for intact and degraded human vitreous in physiologic and environmentally perturbed conditions. After validation, the model was used to estimate how age-related changes in vitreous physiology and structure alter oxygen levels at the lens. Methods. A finite-element model for oxygen transport and consumption in the human vitreous was created. Major inputs included ascorbate-mediated oxygen consumption in the vitreous, consumption at the posterior lens surface, and inflow from the retinal vasculature. Concentration-dependent relations were determined from experimental human data or estimated from animal studies, with the impact of all assumptions explored via parameter studies. Results. The model reproduced experimental data in humans, including oxygen partial pressure (Po2) gradients (≈15 mm Hg) across the anterior-posterior extent of the vitreous body, higher oxygen levels at the pars plana relative to the vitreous core, increases in Po2 near the lens after cataract surgery, and equilibration in the vitreous chamber following vitrectomy. Loss of the antioxidative capacity of ascorbate increases oxygen levels 3-fold at the lens surface. Homogeneous vitreous degeneration (liquefaction), but not partial posterior vitreous detachment, greatly increases oxygen exposure to the lens. Conclusions. Ascorbate content and the structure of the vitreous gel are critical determinants of lens oxygen exposure. Minimally invasive surgery and restoration of vitreous structure warrant further attention as strategies for preventing nuclear cataracts. PMID:24008409

Computational model for oxygen transport and consumption in human vitreous.

PubMed

Filas, Benjamen A; Shui, Ying-Bo; Beebe, David C

2013-10-15

Previous studies that measured liquefaction and oxygen content in human vitreous suggested that exposure of the lens to excess oxygen causes nuclear cataracts. Here, we developed a computational model that reproduced available experimental oxygen distributions for intact and degraded human vitreous in physiologic and environmentally perturbed conditions. After validation, the model was used to estimate how age-related changes in vitreous physiology and structure alter oxygen levels at the lens. A finite-element model for oxygen transport and consumption in the human vitreous was created. Major inputs included ascorbate-mediated oxygen consumption in the vitreous, consumption at the posterior lens surface, and inflow from the retinal vasculature. Concentration-dependent relations were determined from experimental human data or estimated from animal studies, with the impact of all assumptions explored via parameter studies. The model reproduced experimental data in humans, including oxygen partial pressure (Po2) gradients (≈15 mm Hg) across the anterior-posterior extent of the vitreous body, higher oxygen levels at the pars plana relative to the vitreous core, increases in Po2 near the lens after cataract surgery, and equilibration in the vitreous chamber following vitrectomy. Loss of the antioxidative capacity of ascorbate increases oxygen levels 3-fold at the lens surface. Homogeneous vitreous degeneration (liquefaction), but not partial posterior vitreous detachment, greatly increases oxygen exposure to the lens. Ascorbate content and the structure of the vitreous gel are critical determinants of lens oxygen exposure. Minimally invasive surgery and restoration of vitreous structure warrant further attention as strategies for preventing nuclear cataracts.

Effect of 2,3-diphosphoglycerate on oxygen affinity of blood in sickle cell anemia

PubMed Central

Charache, Samuel; Grisolia, Santiago; Fiedler, Adam J.; Hellegers, Andre E.

1970-01-01

Blood of patients with sickle cell anemia (SS) exhibits decreased affinity for oxygen, although the oxygen affinity of hemoglobin S is the same as that of hemoglobin A. SS red cells contain more 2,3-diphosphoglycerate (DPG) than normal erythrocytes. The oxygen affinity of hemolyzed red cells is decreased by added DPG, and hemolysates prepared from SS red cells do not differ from normal hemolysates in this regard. Reduction of oxygen affinity to the levels found in intact SS red cells required DPG concentrations in excess of those found in most SS patients. The same was true of oxygen affinity of patients with pyruvate kinase deficiency. Other organic phosphates, as well as inorganic ions, are known to alter the oxygen affinity of dilute solutions of hemoglobin. These substances, the state of aggregation of hemoglobin molecules, and cytoarchitectural factors probably play roles in determining oxygen affinity of both normal and SS red cells. PMID:5443181

Dynamin-related protein inhibitor downregulates reactive oxygen species levels to indirectly suppress high glucose-induced hyperproliferation of vascular smooth muscle cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maimaitijiang, Alimujiang; Zhuang, Xinyu; Jiang, Xiaofei

Hyperproliferation of vascular smooth muscle cells is a pathogenic mechanism common in diabetic vascular complications and is a putatively important therapeutic target. This study investigated multiple levels of biology, including cellular and organellar changes, as well as perturbations in protein synthesis and morphology. Quantitative and qualitative analysis was utilized to assess the effect of mitochondrial dynamic changes and reactive oxygen species(ROS) levels on high-glucose-induced hyperproliferation of vascular smooth muscle cells. The data demonstrated that the mitochondrial fission inhibitor Mdivi-1 and downregulation of ROS levels both effectively inhibited the high-glucose-induced hyperproliferation of vascular smooth muscle cells. Downregulation of ROS levels playedmore » a more direct role and ROS levels were also regulated by mitochondrial dynamics. Increased ROS levels induced excessive mitochondrial fission through dynamin-related protein (Drp 1), while Mdivi-1 suppressed the sensitivity of Drp1 to ROS levels, thus inhibiting excessive mitochondrial fission under high-glucose conditions. This study is the first to propose that mitochondrial dynamic changes and ROS levels interact with each other and regulate high-glucose-induced hyperproliferation of vascular smooth muscle cells. This finding provides novel ideas in understanding the pathogenesis of diabetic vascular remodeling and intervention. - Highlights: • Mdivi-1 inhibits VSMC proliferation by lowering ROS level in high-glucose condition. • ROS may be able to induce mitochondrial fission through Drp1 regulation. • Mdivi-1 can suppress the sensitivity of Drp1 to ROS.« less

Long-term manganese-toxicity-induced alterations of physiology and leaf protein profiles in two Citrus species differing in manganese-tolerance.

PubMed

You, Xiang; Yang, Lin-Tong; Qi, Yi-Ping; Guo, Peng; Lai, Ning-Wei; Ye, Xin; Li, Qiang; Chen, Li-Song

2017-11-01

Manganese (Mn)-intolerant 'Sour pummelo' (Citrus grandis) and Mn-tolerant 'Xuegan' (Citrus sinensis) seedlings were irrigated for 17 weeks with 2 (control) or 600μM (Mn-toxicity or -excess) MnSO 4 . C. sinensis had higher Mn-tolerance than C. grandis, as indicated by the higher photosynthesis rates in Mn-excess C. sinensis leaves. Under Mn-toxicity, Mn levels were similar between C. sinensis and C. grandis roots, but lower in C. sinensis leaves than in C. grandis leaves. This might be responsible for C. sinensis Mn-tolerance. Using two-dimensional electrophoresis, we identified more differentially abundant proteins (DAPs) in Mn-excess C. grandis than in Mn-excess C. sinensis leaves, which agrees with the higher Mn levels in Mn-excess C. grandis leaves. DAPs were mainly related to carbohydrate and energy metabolism, stress response, and protein and amino acid metabolism. DAPs involved in the cytoskeleton and signal transduction were found only in Mn-excess C. grandis leaves. We isolated more photosynthesis-related proteins with decreased abundances in Mn-excess C. grandis leaves than in Mn-excess C. sinensis leaves, which might account for the larger decrease in photosynthesis rates in C. grandis leaves. The abundances of proteins involved in reactive oxygen species (ROS) scavenging and photorespiration were increased in Mn-excess C. grandis leaves, while only proteins involved in ROS detoxification were increased in Mn-excess C. sinensis leaves. This agrees with the increased requirement for dissipating the excess absorbed light energy, which was higher in Mn-excess C. grandis leaves than Mn-excess C. sinensis leaves because Mn-toxicity inhibited photosynthesis to a greater degree in C. grandis leaves. Copyright © 2017 Elsevier GmbH. All rights reserved.

Clusters of anthropometric indicators of body fat associated with maximum oxygen uptake in adolescents

PubMed Central

2018-01-01

Introduction The aim of this study was to evaluate different clusters of anthropometric indicators (body mass index | BMI |, waist circumference | WC |, waist-to-height ratio | WHtR |, triceps skinfold |TR SF|, subscapular skinfold |SE SF|, sum of the triceps and subscapular skinfolds | ΣTR + SE |, and sum of the triceps, subscapular and suprailiac folds | ΣTR + SE + SI|) associated with the VO2max levels in adolescents. Methods The study included 1,132 adolescents (aged 14–19 years) enrolled in public schools of São José, Santa Catarina, Brazil, in the 2014 academic year. The dependent variable was the cluster of anthropometric indicators (BMI, WC, WHtR, TR SF, SE SF, SI SF, ΣTR + SE and ΣTR + SE + SI) of excess body fat. The independent variable was maximum oxygen uptake (VO2max), estimated by the modified Canadian aerobic fitness test—mCAFT. Control variables were: age, skin color, economic level, maternal education, physical activity and sexual maturation. Multinomial logistic regression was used for associations between the dependent and independent variables. Binary logistic regression was performed to identify the association between adolescents with all anthropometric indicators in excess and independent variables. Results One in ten adolescents presented all anthropometric indicators of excess body fat. Multinomial regression showed that with each increase of one VO2max unit, the odds of adolescents having three, four, five or more anthropometric indicators of excess body fat decreased by 0.92, 0.85 and 0.73 times, respectively. In the binary regression, this fact was reconfirmed, demonstrating that with each increase of one VO2max unit, the odds of adolescents having simultaneously the eight anthropometric indicators of excess body fat decreased by 0.55. Conclusion It was concluded that with each increase of one VO2max unit, adolescents decreased the odds of simultaneously presenting three or more anthropometric indicators of excess body fat, regardless of biological, economic and lifestyle factors. In addition, the present study identified that one in ten adolescents had all anthropometric indicators of excess body fat. PMID:29534098

Clusters of anthropometric indicators of body fat associated with maximum oxygen uptake in adolescents.

PubMed

Gonçalves, Eliane Cristina de Andrade; Nunes, Heloyse Elaine Gimenes; Silva, Diego Augusto Santos

2018-01-01

The aim of this study was to evaluate different clusters of anthropometric indicators (body mass index | BMI |, waist circumference | WC |, waist-to-height ratio | WHtR |, triceps skinfold |TR SF|, subscapular skinfold |SE SF|, sum of the triceps and subscapular skinfolds | ΣTR + SE |, and sum of the triceps, subscapular and suprailiac folds | ΣTR + SE + SI|) associated with the VO2max levels in adolescents. The study included 1,132 adolescents (aged 14-19 years) enrolled in public schools of São José, Santa Catarina, Brazil, in the 2014 academic year. The dependent variable was the cluster of anthropometric indicators (BMI, WC, WHtR, TR SF, SE SF, SI SF, ΣTR + SE and ΣTR + SE + SI) of excess body fat. The independent variable was maximum oxygen uptake (VO2max), estimated by the modified Canadian aerobic fitness test-mCAFT. Control variables were: age, skin color, economic level, maternal education, physical activity and sexual maturation. Multinomial logistic regression was used for associations between the dependent and independent variables. Binary logistic regression was performed to identify the association between adolescents with all anthropometric indicators in excess and independent variables. One in ten adolescents presented all anthropometric indicators of excess body fat. Multinomial regression showed that with each increase of one VO2max unit, the odds of adolescents having three, four, five or more anthropometric indicators of excess body fat decreased by 0.92, 0.85 and 0.73 times, respectively. In the binary regression, this fact was reconfirmed, demonstrating that with each increase of one VO2max unit, the odds of adolescents having simultaneously the eight anthropometric indicators of excess body fat decreased by 0.55. It was concluded that with each increase of one VO2max unit, adolescents decreased the odds of simultaneously presenting three or more anthropometric indicators of excess body fat, regardless of biological, economic and lifestyle factors. In addition, the present study identified that one in ten adolescents had all anthropometric indicators of excess body fat.

Direct oxygen uptake from air by novel glycogen accumulating organism dominated biofilm minimizes excess sludge production.

PubMed

Hossain, Md Iqbal; Paparini, Andrea; Cord-Ruwisch, Ralf

2018-05-29

The cost associated with treatment and disposal of excess sludge produced is one of the greatest operational expenses in wastewater treatment plants. In this study, we quantify and explain greatly reduced excess sludge production in the novel glycogen accumulating organism (GAO) dominated drained biofilm system previously shown to be capable of extremely energy efficient removal of organic carbon (biological oxygen demand or BOD) from wastewater. The average excess sludge production rate was 0.05 g VSS g -1 BOD (acetate) removed, which is about 9-times lower than that of comparative studies using the same acetate based synthetic wastewater. The substantially lower sludge yield was attributed to a number of features such as the high oxygen consumption facilitated by direct oxygen uptake from air, high biomass content (21.41 g VSS L -1 of reactor), the predominance of the GAO (Candidatus competibacter) with a low growth yield and the overwhelming presence of the predatory protozoa (Tetramitus) in the biofilm. Overall, the combination of low-energy requirement for air supply (no compressed air supply) and the low excess sludge production rate, could make this novel "GAO drained biofilm" process one of the most economical ways of biological organic carbon removal from wastewater. Copyright © 2018. Published by Elsevier B.V.

Radicals are required for thiol etching of gold particles

PubMed Central

Dreier, Timothy A.

2016-01-01

Etching of gold with excess thiol ligand is used in both synthesis and analysis of gold particles. Mechanistically, the process of etching gold with excess thiol is opaque. Previous studies have obliquely considered the role of oxygen in thiolate etching of gold. Herein, we show that oxygen or a radical initator is a necessary component for efficient etching of gold by thiolates. Attenuation of the etching process by radical scavengers in the presence of oxygen, and the restoration of activity by radical initiators under inert atmosphere, strongly implicate the oxygen radical. These data led us to propose an atomistic mechanism in which the oxygen radical initiates the etching process. PMID:26089294

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aikawa, Shinya, E-mail: aikawa@cc.kogakuin.ac.jp, E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Research Institute for Science and Technology, Kogakuin University, Hachioji, Tokyo 192-0015; Mitoma, Nobuhiko

We discuss the environmental instability of amorphous indium oxide (InO{sub x})-based thin-film transistors (TFTs) in terms of the excess oxygen in the semiconductor films. A comparison between amorphous InO{sub x} doped with low and high concentrations of oxygen binder (SiO{sub 2}) showed that out-diffusion of oxygen molecules causes drastic changes in the film conductivity and TFT turn-on voltages. Incorporation of sufficient SiO{sub 2} could suppress fluctuations in excess oxygen because of the high oxygen bond-dissociation energy and low Gibbs free energy. Consequently, the TFT operation became rather stable. The results would be useful for the design of reliable oxide TFTsmore » with stable electrical properties.« less

Optimal diving behaviour and respiratory gas exchange in birds.

PubMed

Halsey, Lewis G; Butler, Patrick J

2006-11-01

This review discusses the advancements in our understanding of the physiology and behaviour of avian diving that have been underpinned by optimal foraging theory and the testing of optimal models. To maximise their foraging efficiency during foraging periods, diving birds must balance numerous factors that are directly or indirectly related to the replenishment of the oxygen stores and the removal of excess carbon dioxide. These include (1) the time spent underwater (which diminishes the oxygen supply, increases carbon dioxide levels and may even include a build up of lactate due to anaerobic metabolism), (2) the time spent at the surface recovering from the previous dive and preparing for the next (including reloading their oxygen supply, decreasing their carbon dioxide levels and possibly also metabolising lactate) and (3) the trade-off between maximising oxygen reserves for consumption underwater by taking in more air to the respiratory system, and minimising the energy costs of positive buoyancy caused by this air, to maximise the time available underwater to forage. Due to its importance in avian diving, replenishment of the oxygen stores has become integral to models of optimal diving, which predict the time budgeting of animals foraging underwater. While many of these models have been examined qualitatively, such tests of predictive trends appear fallible and only quantifiable support affords strong evidence of their predictive value. This review describes how the quantification of certain optimal diving models, using tufted ducks, indeed demonstrates some predictive success. This suggests that replenishment of the oxygen stores and removal of excess carbon dioxide have significant influences on the duration of the surface period between dives. Nevertheless, present models are too simplistic to be robust predictors of diving behaviour for individual animals and it is proposed that they require refinement through the incorporation of other variables that also influence diving behaviour such as, perhaps, prey density and predator avoidance.

Excess post-exercise oxygen consumption in adult sockeye (Oncorhynchus nerka) and coho (O. kisutch) salmon following critical speed swimming.

PubMed

Lee, C G; Farrell, A P; Lotto, A; Hinch, S G; Healey, M C

2003-09-01

The present study measured the excess post-exercise oxygen cost (EPOC) following tests at critical swimming speed (Ucrit) in three stocks of adult, wild, Pacific salmon (Oncorhynchus sp.) and used EPOC to estimate the time required to return to their routine level of oxygen consumption (recovery time) and the total oxygen cost of swimming to Ucrit. Following exhaustion at Ucrit, recovery time was 42-78 min, depending upon the fish stock. The recovery times are several-fold shorter than previously reported for juvenile, hatchery-raised salmonids. EPOC varied fivefold among the fish stocks, being greatest for Gates Creek sockeye salmon (O. nerka), which was the salmon stock that had the longest in-river migration, experienced the warmest temperature and achieved the highest maximum oxygen consumption compared with the other salmon stocks that were studied. EPOC was related to Ucrit, which in turn was directly influenced by ambient test temperature. The non-aerobic cost of swimming to Ucrit was estimated to add an additional 21.4-50.5% to the oxygen consumption measured at Ucrit. While these non-aerobic contributions to swimming did not affect the minimum cost of transport, they were up to three times higher than the value used previously for an energetic model of salmon migration in the Fraser River, BC, Canada. As such, the underestimate of non-aerobic swimming costs may require a reevaluation of the importance of how in-river barriers like rapids and bypass facilities at dams, and year-to-year changes in river flows and temperatures, affect energy use and hence migration success.

Preimpoundment water quality of Raystown Branch Juniata River and six tributary streams, south-central Pennsylvania

USGS Publications Warehouse

Williams, Donald R.

1976-01-01

The Raystown Branch Juniata River watershed, which is the main water source for Raystown Lake, is a 960-square-mile (2,490 square kilometres) drainage basin in south-central Pennsylvania. Preimpoundment water-quality data were collected on the Raystown Branch and six tributary st.reams in the basin. Specific conductance values varied inversely with water discharge. The pH values were extremely low only at the Shoup Run site. Dissolved oxygen concentrations observed at all sites indicated a relatively high oxygen saturation level throughout the year. Seasonal variations in nitrate-N and orthophosphate-P levels were measured at the main inflow station at Saxton, Pa. The highest concentrations of nitrate-N and orthophosphate-P occurred in the winter and spring months and the lowest concentrations were measured dur:l.ng the swnmer and fall. Bacteriological data indicated no excessive -amounts of fecal matter present at the inflows. Soil samples collected at four sites in the impoundment area were predominantly of the Barbour, Philo, and Basher series, which are considered to be highly fertile soils with silt-loam and sandy~loam textures. Morphological features of the lake basin and low nutrient levels at the inflows should prevent excessive weed growth around the lake perimeter.

Evolution of Defect Structures and Deep Subgap States during Annealing of Amorphous In-Ga-Zn Oxide for Thin-Film Transistors

NASA Astrophysics Data System (ADS)

Jia, Junjun; Suko, Ayaka; Shigesato, Yuzo; Okajima, Toshihiro; Inoue, Keiko; Hosomi, Hiroyuki

2018-01-01

We investigate the evolution behavior of defect structures and the subgap states in In-Ga-Zn oxide (IGZO) films with increasing postannealing temperature by means of extended x-ray absorption fine-structure (EXAFS) measurements, positron annihilation lifetime spectroscopy (PALS), and cathodoluminescence (CL) spectroscopy, aiming to understand the relationship between defect structures and subgap states. EXAFS measurements reveal the varied oxygen coordination numbers around cations during postannealing and confirm two types of point defects, namely, excess oxygen around Ga atoms and oxygen deficiency around In and/or Zn atoms. PALS suggests the existence of cation-vacancy (VM )-related clusters with neutral or negative charge in both amorphous and polycrystalline IGZO films. CL spectra show a main emission band at approximately 1.85 eV for IGZO films, and a distinct shoulder located at about 2.15 eV for IGZO films postannealed above 600 °C . These two emission bands are assigned to a recombination between the electrons in the conduction band and/or in the shallow donor levels near the conduction band and the acceptors trapped above the valence-band maximum. The shallow donors are attributed to the oxygen deficiency, and the acceptors are thought to possibly arise from the excess oxygen or the VM-related clusters. These results open up an alternative route for understanding the device instability of amorphous IGZO-based thin-film transistors, especially the presence of the neutral or negatively charged VM-related clusters in amorphous IGZO films.

Method and apparatus for controlling fuel/air mixture in a lean burn engine

DOEpatents

Kubesh, John Thomas; Dodge, Lee Gene; Podnar, Daniel James

1998-04-07

The system for controlling the fuel/air mixture supplied to a lean burn engine when operating on natural gas, gasoline, hydrogen, alcohol, propane, butane, diesel or any other fuel as desired. As specific humidity of air supplied to the lean burn engine increases, the oxygen concentration of exhaust gas discharged by the engine for a given equivalence ratio will decrease. Closed loop fuel control systems typically attempt to maintain a constant exhaust gas oxygen concentration. Therefore, the decrease in the exhaust gas oxygen concentration resulting from increased specific humidity will often be improperly attributed to an excessive supply of fuel and the control system will incorrectly reduce the amount of fuel supplied to the engine. Also, the minimum fuel/air equivalence ratio for a lean burn engine to avoid misfiring will increase as specific humidity increases. A relative humidity sensor to allow the control system to provide a more enriched fuel/air mixture at high specific humidity levels. The level of specific humidity may be used to compensate an output signal from a universal exhaust gas oxygen sensor for changing oxygen concentrations at a desired equivalence ratio due to variation in specific humidity specific humidity. As a result, the control system will maintain the desired efficiency, low exhaust emissions and power level for the associated lean burn engine regardless of the specific humidity level of intake air supplied to the lean burn engine.

Radicals Are Required for Thiol Etching of Gold Particles.

PubMed

Dreier, Timothy A; Ackerson, Christopher J

2015-08-03

Etching of gold with an excess of thiol ligand is used in both synthesis and analysis of gold particles. Mechanistically, the process of etching gold with excess thiol is unclear. Previous studies have obliquely considered the role of oxygen in thiolate etching of gold. Herein, we show that oxygen or a radical initiator is a necessary component for efficient etching of gold by thiolates. Attenuation of the etching process by radical scavengers in the presence of oxygen, and the restoration of activity by radical initiators under inert atmosphere, strongly implicate the oxygen radical. These data led us to propose an atomistic mechanism in which the oxygen radical initiates the etching process. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Quadrupedal locomotor performance in two species of arboreal squirrels: predicting energy savings of gliding

Treesearch

Elizabeth A. Flaherty; Merav Ben-David; Winston P. Smith

2010-01-01

Gliding allows mammals to exploit canopy habitats of old-growth forests possibly as a means to save energy. To assess costs of quadrupedal locomotion for a gliding arboreal mammal, we used open-flow respirometry and a variable-speed treadmill to measure oxygen consumption and to calculate cost of transport, excess exercise oxygen consumption, and excess post-exercise...

The Expanding Role of Oxygen Free Radicals in Clinical Medicine

PubMed Central

Katz, Murray A.

1986-01-01

In 1969 McCord and Fridovich discovered superoxide dismutase, which converts the oxygen free radical O2- to hydrogen peroxide H2O2. In the presence of excess O2-, H2O2 may then undergo further reduction to the highly toxic hydroxyl radical, OH•. Since the description of this enzymatic process, there has been explosive growth in related biochemical research, which has now percolated through to clinical investigation. The hypoxanthine-xanthine oxidase system originally used as a radical production model has a close counterpart in the ischemia-reperfusion phenomenon purported to cause diseases of heart, brain and gastrointestinal tract, and free radicals are now known to have a critical role in postphagocytic bacterial killing. Prototypic deficiency diseases such as chronic granulomatous disease are now recognized. Some evidence indicates that excess states such as perhaps Batten's disease also occur, and environmental influences such as selenium and vitamin E deficiency may augment free radical levels. Many disorders including microvasculopathies, noncardiogenic pulmonary edema, glomerulopathies and radiation damage may owe part of their proximate pathogenesis to free radicals. Control of tissue free radical levels is now pharmacologically feasible and perhaps justified for specific diseases. PMID:3521094

Increased capillaries in mitochondrial myopathy: implications for the regulation of oxygen delivery.

PubMed

Taivassalo, Tanja; Ayyad, Karen; Haller, Ronald G

2012-01-01

Human skeletal muscle respiratory chain defects restrict the ability of working muscle to extract oxygen from blood, and result in a hyperkinetic circulation during exercise in which oxygen delivery is excessive relative to oxygen uptake and oxygen levels within contracting muscle are abnormally high. To investigate the role of the muscle microcirculation in this anomalous circulatory response and possible implications for the regulation of muscle angiogenesis, we assessed muscle oxidative capacity during cycle exercise and determined capillary levels and distribution and vascular endothelial growth factor expression in quadriceps muscle biopsies in patients with mitochondrial myopathy attributable to heteroplasmic mitochondrial DNA mutations. We found that in patients with mitochondrial myopathy, muscle capillary levels were twice that of sedentary healthy subjects (3.0 ± 0.9% compared with 1.4 ± 0.3%, P < 0.001) despite the fact that oxygen utilization during peak cycle exercise was half that of control subjects (11.1 ± 4.0 ml/kg/min compared with 20.7 ± 7.9 ml/kg/min, P < 0.01); that capillary area was greatest in patients with the most severe muscle oxidative defects and was more than two times higher around muscle fibre segments with defective (i.e. cytochrome oxidase negative/succinic dehydrogenase-positive or 'ragged-red' fibres) compared with more preserved respiratory chain function; and that vascular endothelial growth factor expression paralleled capillary distribution. The increased muscle capillary levels in patients correlated directly (r(2) = 0.68, P < 0.05) with the severity of the mismatch between systemic oxygen delivery (cardiac output) and oxygen utilization during cycle exercise. Our results suggest that capillary growth is increased as a result of impaired muscle oxidative phosphorylation in mitochondrial myopathy, thus promoting increased blood flow to respiration-incompetent muscle fibres and a mismatch between oxygen delivery and utilization during exercise. Furthermore, the finding of high capillary levels despite elevated tissue oxygen levels during exercise in respiration-deficient muscle fibres implies that mitochondrial metabolism activates angiogenesis in skeletal muscle by a mechanism that is independent of hypoxia.

Steam generator on-line efficiency monitor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, R.K.; Kaya, A.; Keyes, M.A. IV

1987-08-04

This patent describes a system for automatically and continuously determining the efficiency of a combustion process in a fossil-fuel fired vapor generator for utilization by an automatic load control system that controls the distribution of a system load among a plurality of vapor generators, comprising: a first function generator, connected to an oxygen transducer for sensing the level of excess air in the flue gas, for generating a first signal indicative of the total air supplied for combustion in percent by weight; a second function generator, connected to a combustibles transducer for sensing the level of combustibles in the fluemore » gas, for generating a second signal indicative of the percent combustibles present in the flue gas; means for correcting the first signal, connected to the first and second function generators, when the oxygen transducer is of a type that operates at a temperature level sufficient to cause the unburned combustibles to react with the oxygen present in the flue gas; an ambient air temperature transducer for generating a third signal indicative of the temperature of the ambient air supplied to the vapor generator for combustion.« less

Towards a new proxy of continental atmospheric humidity: the triple oxygen isotopic composition of plant biosilica

NASA Astrophysics Data System (ADS)

Alexandre, A. E.; Pauchet, S.; Landais, A.; Piel, C.; Devidal, S.; Roy, J.; Vallet-Coulomb, C.; Sonzogni, C.; Pasturel, M.; Cornuault, P.; Xin, J.; Mazur, J. C.; Prie, F.; Bentaleb, I.

2016-12-01

There is a serious lack of proxy suitable for reconstructing, in a quantitative way, past changes of continental atmospheric humidity. This reduces the possibility to make model-data comparisons necessary for the implementation of climate models. Over the past 10 years, analytical developments have enabled a few laboratories to reach sufficient precision for measuring the triple oxygen isotopes, expressed by the 17O-excess, in water, water vapor, atmospheric oxygen, and minerals. The 17O-excess represents an alternative to d-excess for investigating relative humidity conditions that prevail during water evaporation. The 17O-excess of water results from the increase of kinetic isotopic fractionation at evaporative sites as a function of decreasing relative humidity. This mechanism occurs at large scales, i.e. during seawater evaporation or during plant canopies transpiration. Unlike deuterium-excess, 17O-excess is supposed to be insensitive to temperature and less sensitive than δD and δ18O to equilibrium fractionation during transport and precipitation. Additionally, the 17O-excess is recorded in biogenic minerals less prone to weathering than organic compounds. Here, we calibrate the 17O-excess of plant biosilica as a new air humidity proxy. First, we examined the behavior of the 17O-excess in soil water, leaf water and phytoliths in growth chambers in response to changes in relative humidity. Second, we measured the 17O-excess of soil phytolith assemblages from inter-tropical savannas and forests distributed along humidity transects. Both approaches show similar dependency of phytolith 17O-excess to relative humidity. The results allow to discuss future calibration directions aimed at estimating the precision of the obtained relationship and at quantifying the successive isotopic fractionations in play at the soil-plant-atmosphere interface, to provide a strong proxy of past atmospheric relative humidity.

Photo-Ultrasonic Study of Extrinsic Photoconductivity in N-Gallium Arsenide

NASA Astrophysics Data System (ADS)

Bradshaw, Randall Grant

We have measured the velocity of piezoelectrically -active, ultrasonic shear waves between 1.5 K and 68 K for undoped and for oxygen-doped n-type GaAs, during and after illumination at 4.2 K. The results reveal photoconductivity, persistent photoconductivity, and thermally stimulated conductivity. In both samples the Fermi level in the dark is controlled by excess non-shallow donors near 0.2 eV below the conduction band. Analysis of these effects in oxygen-doped material indicates that there are mid-gap and much shallower photoionizable levels and that there is an electron trap near 20 meV below the conduction band. The undoped n-GaAs sample exhibits photoconductivity quenching with photons in the range 0.95-1.26 eV which, by analysis of the quenching rate, is attributed to the EL2 defect. In addition, levels with large hole capture coefficients have been detected.

Effect of dissolved oxygen level of water on ultrasonic power measured using calorimetry

NASA Astrophysics Data System (ADS)

Uchida, Takeyoshi; Yoshioka, Masahiro; Horiuchi, Ryuzo

2018-07-01

Ultrasonic therapeutic equipment, which exposes the human body to high-power ultrasound, is used in clinical practice to treat cancer. However, the safety of high-power ultrasound has been questioned because the equipment affects not only cancer cells but also normal cells. To evaluate the safety of ultrasound, it is necessary to accurately measure the ultrasonic power of the equipment. This is because ultrasonic power is a key quantity related to the thermal hazard of ultrasound. However, precise techniques for measuring ultrasonic power in excess of 15 W are yet to be established. We have been studying calorimetry as a precise measurement technique. In this study, we investigated the effect of the dissolved oxygen (DO) level of water on ultrasonic power by calorimetry. The results show that the measured ultrasonic power differed significantly between water samples of different DO levels. This difference in ultrasonic power arose from acoustic cavitation.

Characterization of Oxygen Storage and Structural Properties of Oxygen-Loaded Hexagonal R MnO 3+δ ( R = Ho, Er, and Y)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abughayada, C.; Dabrowski, B.; Kolesnik, S.

2015-09-22

Single-phase polycrystalline samples of stoichiometric RMnO3+delta (R = Er, Y, and Ho) were achieved in the hexagonal P6(3)cm structure through solid state reaction at, similar to 1300 degrees C. Thermogravimetric measurements in oxygen atmospheres demonstrated that samples with the larger Ho and Y show rapid and reversible incorporation of large amounts of excess oxygen (0.3 > delta> 0) at an unusually low temperature range of similar to 190-325 degrees C, indicating the industrial usefulness of RMnO3+delta materials for lower cost thermal swing adsorption processes for oxygen separation from air. Further increase of the excess oxygen intake to delta similar tomore » 0.38 was achieved for all the investigated materials when annealed under high pressures of oxygen. The formation of three oxygen stable phases with 6 = 0, 0.28, and 0.38 was confirmed by thermogravimetric measurements, synchrotron X-rays, and neutron diffraction. In situ synchrotron diffraction proved the thermal stability of these single phases and the regions of their creation and coexistence, and demonstrated that the stability of the delta = 0.28 phase increases with the ionic size of the R ion. Structural modeling using neutron powder diffraction for oxygen excess phases describes the formation and details of a large R3c superstructure observed for HoMnO3.28 by tripling the c-axis of the original parent unit cell. Modeling of the RMnO3.38 (R = Y and Er) oxygen-loaded phase converged on a structural model consistent with the symmetry of Pca2(1).« less

Molecular Orbital Principles of Oxygen-Redox Battery Electrodes.

PubMed

Okubo, Masashi; Yamada, Atsuo

2017-10-25

Lithium-ion batteries are key energy-storage devices for a sustainable society. The most widely used positive electrode materials are LiMO 2 (M: transition metal), in which a redox reaction of M occurs in association with Li + (de)intercalation. Recent developments of Li-excess transition-metal oxides, which deliver a large capacity of more than 200 mAh/g using an extra redox reaction of oxygen, introduce new possibilities for designing higher energy density lithium-ion batteries. For better engineering using this fascinating new chemistry, it is necessary to achieve a full understanding of the reaction mechanism by gaining knowledge on the chemical state of oxygen. In this review, a summary of the recent advances in oxygen-redox battery electrodes is provided, followed by a systematic demonstration of the overall electronic structures based on molecular orbitals with a focus on the local coordination environment around oxygen. We show that a π-type molecular orbital plays an important role in stabilizing the oxidized oxygen that emerges upon the charging process. Molecular orbital principles are convenient for an atomic-level understanding of how reversible oxygen-redox reactions occur in bulk, providing a solid foundation toward improved oxygen-redox positive electrode materials for high energy-density batteries.

Glucocorticoid Signaling and Bone Biology.

PubMed

Komori, T

2016-11-01

Since glucocorticoids remain an effective therapeutic option for the treatment of many inflammatory and autoimmune diseases, glucocorticoid-induced osteoporosis is the most common form of secondary osteoporosis. Fractures may occur in as many as 30-50% of patients receiving chronic glucocorticoid therapy. Under physiological conditions, glucocorticoids are required for normal bone development due to their regulation of osteoblast differentiation, possibly via the Wnt/β-catenin pathway and TSC22D3. However, serum levels of endogenous corticosterone are elevated in aged mice and glucocorticoids exert negative effects on the survival of osteoblasts and osteocytes as well as angiogenesis. Glucocorticoid treatments impair bone formation and enhance bone resorption. Excess glucocorticoids induce osteoblast and osteocyte apoptosis by increasing pro-apoptotic molecules, reactive oxygen species, and endoplasmic reticulum stress and suppressing the Wnt/β-catenin pathway. Autophagy protects osteocytes from glucocorticoid-induced apoptosis, but passed some threshold, the process of autophagy leads the cells to apoptosis. Excess glucocorticoids impair osteoblastogenesis by inducing Wnt antagonists, including Dkk1, Sost, and sFRP-1. However, the findings are controversial and the involvement of Wnt antagonists requires further study. Excess glucocorticoids reduce the phosphorylation of Akt and GSK3β, which enhances the degradation of β-catenin. Excess glucocorticoids have been shown to modulate the expression of miRNAs, including miR-29a, miR-34a-5p, and miR-199a-5p, which regulate the proliferation and differentiation of osteoblast lineage cells. Excess glucocorticoids also enhance bone resorption by reducing OPG expression, increasing Rankl expression and reactive oxygen species, and prolonging the life span of osteoclasts; however, they also suppress the bone-degrading capacity of osteoclasts by disturbing the organization of the cytoskeleton. © Georg Thieme Verlag KG Stuttgart · New York.

Redox signaling and stress tolerance in plants: a focus on vitamin E.

PubMed

Miret, Javier A; Munné-Bosch, Sergi

2015-03-01

Plants are subject to specific redox processes, in which photosynthesis plays a prominent role. Chloroplasts function in light at high oxygen tensions and are enormous generators of reactive oxygen species, mainly singlet oxygen. This side product of photosynthesis inflicts damage to thylakoid membranes at high concentrations, but at the same time it is an essential component of cellular signaling. Detoxification of singlet oxygen is achieved by different means, including quenching and scavenging by tocopherols, responsible for controlling singlet oxygen levels, and the extent of lipid peroxidation in chloroplasts. Here, environmental conditions leading to excess light in chloroplasts will be used to show the importance of singlet oxygen, tocopherols, and lipid peroxidation in cell signaling. Defects in antioxidant protection (e.g., tocopherol deficiency) can lead to increased photo-oxidative damage, but also to the activation of defense pathways, illustrating the phenotypic plasticity evolved by plants to withstand stress. Most importantly, these studies show how redox signaling processes are integrated within the cell and illustrate the great capacity of plants to adapt to their environment. © 2015 New York Academy of Sciences.

Current Practices and Attitudes Regarding Use of Inhaled Nitric Oxide in the NICU

PubMed Central

Kayton, Allyson; Timoney, Paula; Vargo, Lyn; Perez, Jose A.

2018-01-01

Background: Excessive supplemental oxygen exposure in the neonatal intensive care unit (NICU) can be associated with oxygen-related toxicities, which can lead to negative clinical consequences. Use of inhaled nitric oxide (iNO) can be a successful strategy for avoiding hyperoxia in the NICU. iNO selectively produces pulmonary vasodilation and has been shown to improve oxygenation parameters across the spectrum of disease severity, from mild to very severe, in neonates with hypoxic respiratory failure associated with persistent pulmonary hypertension of the newborn. Purpose: An online survey was conducted among members of the National Association of Neonatal Nurse Practitioners to gain insight into the level of understanding and knowledge among neonatal nurse practitioners (NNPs) about optimizing supplemental oxygen exposure and the use of iNO in the NICU setting. Results: Of 937 NNP respondents, 51% reported that their healthcare team typically waits until the fraction of inspired oxygen level is 0.9 or more before adding iNO in patients not responding to oxygen ventilation alone. Among respondents with 1 or more iNO-treated patients per month, only 35% reported they know the oxygenation index level at which iNO should be initiated. Less than 20% of NNPs reported perceived benefits associated with early initiation of iNO for preventing progression to use of extracorporeal membrane oxygenation or reducing the length of hospital stay, and about one-third of respondents reported they believe early iNO use minimizes hyperoxia. Implications for Practice: More education is needed for NNPs regarding the negative effects of oxidative stress in neonates. Implications for Research: Additional clinical trials investigating the most beneficial strategies for avoiding neonatal hyperoxia are warranted. PMID:29465446

Oxygen isotope exchange with quartz during pyrolysis of silver sulfate and silver nitrate.

PubMed

Schauer, Andrew J; Kunasek, Shelley A; Sofen, Eric D; Erbland, Joseph; Savarino, Joel; Johnson, Ben W; Amos, Helen M; Shaheen, Robina; Abaunza, Mariana; Jackson, Terri L; Thiemens, Mark H; Alexander, Becky

2012-09-30

Triple oxygen isotopes of sulfate and nitrate are useful metrics for the chemistry of their formation. Existing measurement methods, however, do not account for oxygen atom exchange with quartz during the thermal decomposition of sulfate. We present evidence for oxygen atom exchange, a simple modification to prevent exchange, and a correction for previous measurements. Silver sulfates and silver nitrates with excess (17)O were thermally decomposed in quartz and gold (for sulfate) and quartz and silver (for nitrate) sample containers to O(2) and byproducts in a modified Temperature Conversion/Elemental Analyzer (TC/EA). Helium carries O(2) through purification for isotope-ratio analysis of the three isotopes of oxygen in a Finnigan MAT253 isotope ratio mass spectrometer. The Δ(17)O results show clear oxygen atom exchange from non-zero (17)O-excess reference materials to zero (17)O-excess quartz cup sample containers. Quartz sample containers lower the Δ(17)O values of designer sulfate reference materials and USGS35 nitrate by 15% relative to gold or silver sample containers for quantities of 2-10 µmol O(2). Previous Δ(17)O measurements of sulfate that rely on pyrolysis in a quartz cup have been affected by oxygen exchange. These previous results can be corrected using a simple linear equation (Δ(17)O(gold) = Δ(17)O(quartz) * 1.14 + 0.06). Future pyrolysis of silver sulfate should be conducted in gold capsules or corrected to data obtained from gold capsules to avoid obtaining oxygen isotope exchange-affected data. Copyright © 2012 John Wiley & Sons, Ltd.

40 CFR Appendix E to Part 75 - Optional NOX Emissions Estimation Protocol for Gas-Fired Peaking Units and Oil-Fired Peaking Units

Code of Federal Regulations, 2010 CFR

2010-07-01

... the boiler at a normal or conservatively high excess oxygen level in conjunction with these tests....2Substitute 1.25 times the highest NOX emission rate from the baseline correlation tests for the fuel (or fuel... potential NOX emission rate (MER) (as defined in § 72.2 of this chapter) for each unit operating hour...

40 CFR Appendix E to Part 75 - Optional NOX Emissions Estimation Protocol for Gas-Fired Peaking Units and Oil-Fired Peaking Units

Code of Federal Regulations, 2012 CFR

2012-07-01

... the boiler at a normal or conservatively high excess oxygen level in conjunction with these tests....2Substitute 1.25 times the highest NOX emission rate from the baseline correlation tests for the fuel (or fuel... potential NOX emission rate (MER) (as defined in § 72.2 of this chapter) for each unit operating hour...

Do over 200 million healthy altitude residents really suffer from chronic Acid-base disorders?

PubMed

Zubieta-Calleja, Gustavo; Zubieta-Castillo, Gustavo; Zubieta-Calleja, Luis; Ardaya-Zubieta, Gustavo; Paulev, Poul-Erik

2011-01-01

As the oxygen tension of inspired air falls with increasing altitude in normal subjects, hyperventilation ensues. This acute respiratory alkalosis, induces increased renal excretion of bicarbonate, returning the pH back to normal, giving rise to compensated respiratory alkalosis or chronic hypocapnia. It seems a contradiction that so many normal people at high altitude should permanently live as chronic acid-base patients. Blood gas analyses of 1,865 subjects at 3,510 m, reported a P(a)CO(2) (arterial carbon dioxide tension ± SEM) = 29.4 ± 0.16 mmHg and pH = 7.40 ± 0.005. Base excess, calculated with the Van Slyke sea level equation, is -5 mM (milliMolar or mmol/l) as an average, suggesting chronic hypocapnia. THID, a new term replacing "Base Excess" is determined by titration to a pH of 7.40 at a P(a)CO(2) of 5.33 kPa (40 mmHg) at sea level, oxygen saturated and at 37°C blood temperature. Since our new modified Van Slyke equations operate with normal values for P(a)CO(2) at the actual altitude, a calculation of THID will always result in normal values-that is, zero.

Cultured 3T3L1 adipocytes dispose of excess medium glucose as lactate under abundant oxygen availability

NASA Astrophysics Data System (ADS)

Sabater, David; Arriarán, Sofía; Romero, María Del Mar; Agnelli, Silvia; Remesar, Xavier; Fernández-López, José Antonio; Alemany, Marià

2014-01-01

White adipose tissue (WAT) produces lactate in significant amount from circulating glucose, especially in obesity;Under normoxia, 3T3L1 cells secrete large quantities of lactate to the medium, again at the expense of glucose and proportionally to its levels. Most of the glucose was converted to lactate with only part of it being used to synthesize fat. Cultured adipocytes were largely anaerobic, but this was not a Warburg-like process. It is speculated that the massive production of lactate, is a process of defense of the adipocyte, used to dispose of excess glucose. This way, the adipocyte exports glucose carbon (and reduces the problem of excess substrate availability) to the liver, but the process may be also a mechanism of short-term control of hyperglycemia. The in vivo data obtained from adipose tissue of male rats agree with this interpretation.

Excessive sodium ions delivered into cells by nanodiamonds: implications for tumor therapy.

PubMed

Zhu, Ying; Li, Wenxin; Zhang, Yu; Li, Jing; Liang, Le; Zhang, Xiangzhi; Chen, Nan; Sun, Yanhong; Chen, Wen; Tai, Renzhong; Fan, Chunhai; Huang, Qing

2012-06-11

Nanodiamonds (NDs) possess many excellent physical and chemical properties that make them attractive materials for applications in biomedicine. In this paper, the adsorption and delivery of a large amount of sodium ions into the cell interior by NDs in serum-free medium is demonstrated. The excess sodium ions inside the cells induce osmotic stresses followed by cell swelling and an increase in the intracellular levels of calcium and reactive oxygen species (ROS), which leads to severe cellular damage. In complete culture medium, however, serum proteins wrapped around the NDs effectively prevent the sodium ions from adsorbing onto the NDs, and thus the NDs show no cytotoxicity. This work is the first to elaborate on the correlation between the sodium ions adsorbed on the nanomaterials and their bio-effects. Excessive ions delivered into cells by NDs might have potential applications in tumor therapy. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Inducible NOS inhibitor 1400W reduces hypoxia/re-oxygenation injury in rat lung.

PubMed

Rus, Alma; Castro, Lourdes; Del Moral, Maria Luisa; Peinado, Angeles

2010-01-01

Nitric oxide (NO(*)) from inducible NO(*) synthase (iNOS) has been reported to either protect against, or contribute to, hypoxia/re-oxygenation lung injury. The present work aimed to clarify this double role in the hypoxic lung. With this objective, a follow-up study was made in Wistar rats submitted to hypoxia/re-oxygenation (hypoxia for 30 min; re-oxygenation of 0 h, 48 h, and 5 days), with or without prior treatment with the selective iNOS inhibitor 1400W (10 mg/kg). NO(*) levels (NOx), lipid peroxidation, apoptosis, and protein nitration were analysed. This is the first time-course study which investigates the effects of 1400W during hypoxia/re-oxygenation in the rat lung. The results showed that the administration of 1400W lowered NOx levels in all the experimental groups. In addition, lipid peroxidation, the percentage of apoptotic cells, and nitrated protein expression fell in the late post-hypoxia period (48 h and 5 days). Our results reveal that the inhibition of iNOS in the hypoxic lung reduced the damage observed before the treatment with 1400W, suggesting that iNOS-derived NO(*) may exert a negative effect on this organ during hypoxia/re-oxygenation. These findings are notable, since they indicate that any therapeutic strategy aimed at controlling excess generation of NO(*) from iNOS may be useful in alleviating NO(*)-mediated adverse effects in hypoxic lungs.

Fundamental roles of reactive oxygen species and protective mechanisms in the female reproductive system.

PubMed

Fujii, Junichi; Iuchi, Yoshihito; Okada, Futoshi

2005-09-02

Controlled oxidation, such as disulfide bond formation in sperm nuclei and during ovulation, plays a fundamental role in mammalian reproduction. Excess oxidation, however, causes oxidative stress, resulting in the dysfunction of the reproductive process. Antioxidation reactions that reduce the levels of reactive oxygen species are of prime importance in reproductive systems in maintaining the quality of gametes and support reproduction. While anti-oxidative enzymes, such as superoxide dismutase and peroxidase, play a central role in eliminating oxidative stress, reduction-oxidation (redox) systems, comprised of mainly glutathione and thioredoxin, function to reduce the levels of oxidized molecules. Aldo-keto reductase, using NADPH as an electron donor, detoxifies carbonyl compounds resulting from the oxidation of lipids and proteins. Thus, many antioxidative and redox enzyme genes are expressed and aggressively protect gametes and embryos in reproductive systems.

Dissociation of local and global skeletal muscle oxygen transport metrics in type 2 diabetes.

PubMed

Mason McClatchey, P; Bauer, Timothy A; Regensteiner, Judith G; Schauer, Irene E; Huebschmann, Amy G; Reusch, Jane E B

2017-08-01

Exercise capacity is impaired in type 2 diabetes, and this impairment predicts excess morbidity and mortality. This defect appears to involve excess skeletal muscle deoxygenation, but the underlying mechanisms remain unclear. We hypothesized that reduced blood flow, reduced local recruitment of blood volume/hematocrit, or both contribute to excess skeletal muscle deoxygenation in type 2 diabetes. In patients with (n=23) and without (n=18) type 2 diabetes, we recorded maximal reactive hyperemic leg blood flow, peak oxygen utilization during cycling ergometer exercise (VO 2peak ), and near-infrared spectroscopy-derived measures of exercise-induced changes in skeletal muscle oxygenation and blood volume/hematocrit. We observed a significant increase (p<0.05) in skeletal muscle deoxygenation in type 2 diabetes despite similar blood flow and recruitment of local blood volume/hematocrit. Within the control group skeletal muscle deoxygenation, local recruitment of microvascular blood volume/hematocrit, blood flow, and VO 2peak are all mutually correlated. None of these correlations were preserved in type 2 diabetes. These results suggest that in type 2 diabetes 1) skeletal muscle oxygenation is impaired, 2) this impairment may occur independently of bulk blood flow or local recruitment of blood volume/hematocrit, and 3) local and global metrics of oxygen transport are dissociated. Copyright © 2017 Elsevier Inc. All rights reserved.

Effects of varying hematocrit on intestinal oxygen uptake in neonatal lambs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Holzman, I.R.; Tabata, B.; Edelstone, D.I.

1985-04-01

The authors chronically catheterized 15 newborn lambs (9.5 +/- 2.8 days) and measured intestinal blood flow (Qi) by the radionuclide microsphere technique at hematocrit levels ranging from 10 to 55%. Seven animals were made progressively anemic and eight polycythemic by means of exchange transfusions. Using the Fick principle, they calculated intestinal oxygen delivery (Di O/sub 2/), oxygen consumption (Vi O/sub 2/), and oxygen extraction. Initial base-line values were Qi = 195.5 ml . min-1 . 100 g intestine-1, Di O/sub 2/ = 22.1 ml . min-1 . 100 g-1, Vi O/sub 2/ = 4.8 ml . min-1 . 100 g-1,more » and O/sub 2/ extraction = 22.5%. As the hematocrit was lowered, Di O/sub 2/ decreased and O2 extraction increased and vice versa when the hematocrit was raised. Vi O/sub 2/ remained constant, but Qi did not correlate with changes in hematocrit. However, intestinal blood flow, as a percent distribution of total blood flow, decreased with lower hematocrit levels. At no time was there any evidence of anaerobic metabolism as measured by excess lactate production. The data indicate that the intestines of neonatal lambs are capable of maintaining their metabolic needs over a wide range of oxygen availability induced by a changing hematocrit. The primary mechanism is through alteration of oxygen extraction. Within the range of the experiments, no critically low oxygen availability was attained at which anaerobic metabolism became significant.« less

Nasal high-flow therapy reduces work of breathing compared with oxygen during sleep in COPD and smoking controls: a prospective observational study

PubMed Central

Kirkness, Jason P.; Grote, Ludger; Fricke, Kathrin; Schwartz, Alan R.; Smith, Philip; Schneider, Hartmut

2017-01-01

Patients with chronic obstructive pulmonary disease (COPD) endure excessive resistive and elastic loads leading to chronic respiratory failure. Oxygen supplementation corrects hypoxemia but is not expected to reduce mechanical loads. Nasal high-flow (NHF) therapy supports breathing by reducing dead space, but it is unclear how it affects mechanical loads of patients with COPD. The objective of this study was to compare the effects of low-flow oxygen and NHF therapy on ventilation and work of breathing (WOB) in patients with COPD and controls during sleep. Patients with COPD (n = 12) and controls (n = 6) were recruited and submitted to polysomnography to measure sleep parameters and ventilation in response to administration of oxygen and NHF. A subset of six patients also had an esophageal catheter inserted for the purpose of measuring WOB. Patients with COPD had similar minute ventilation (V̇e) but lower tidal volumes than matched controls. With oxygen, SaO2was increased and V̇e was reduced in both controls and patients with COPD, but there was an increase in transcutaneous CO2 levels. NHF produced a greater reduction in V̇e and was associated with a reduction in CO2 levels. Although NHF halved WOB, oxygen produced only a minor reduction in this parameter. We conclude that oxygen produced little change in WOB, which was associated with CO2 elevations. On the other hand, NHF produced a large reduction in V̇e and WOB with a concomitant decrease in CO2 levels. Our data indicate that NHF improves alveolar ventilation during sleep compared with oxygen and room air in patients with COPD and therefore can decrease their cost of breathing. NEW & NOTEWORTHY Nasal high-flow (NHF) therapy can support ventilation in patients with chronic obstructive pulmonary disease during sleep by decreasing the work of breathing and improving CO2 levels. On the other hand, oxygen supplementation corrects hypoxemia, but it produces only a minimal reduction in work of breathing and is associated with increased CO2 levels. Therefore, NHF can be a useful method to assist ventilation in patients with increased respiratory mechanical loads. PMID:27815367

[Temporal and spatial variations of hydrogen and oxygen isotopes in Tuojia River and its influencing factors.

PubMed

Wu, Hong Bao; Zhao, Qiang; Qin, Xiao Bo; Gao, Qing Zhu; Lyu, Cheng Wen

2018-05-01

The characteristics of hydrogen and oxygen stable isotopes in river is important for regional hydrologic cycle research. To uncover water supply sources in subtropical agricultural basin from a perspective of stable isotopes, field measurements were conducted in four reaches (S 1 , S 2 , S 3 and S 4 ) of Tuojia River from April to August 2017. We analyzed the spatial and temporal variations in hydrogen and oxygen isotopes and deuterium excess parameters and their relationship with precipitation, altitude and water quality. Results showed that hydrogen and oxygen isotopes and deuterium excess values ranged from -43.17‰ to -26.43‰ (-35.50‰±5.44‰), -7.94‰ to -5.70‰ (-6.86‰±0.74‰), and 16.77‰ to 23.49‰ (19.39‰±1.95‰), respectively. Under the influence of monsoon circulation, hydrogen and oxygen isotopes showed substantial seasonal variation, with spring (δD: -29.88‰±3.31‰; δ 18 O: -6.18‰±0.57‰) > summer (δD: -39.25‰±2.65‰; δ 18 O: -7.32‰±0.42‰). The spatial distribution of hydrogen and oxygen isotopes values increased fluctuantly with the position from the sampling site to the river's source, with δD: S 1 ＜S 4 ＜S 3 ＜S 2 , and δ 18 O: S 1 ＜S 3 ＜S 4 ＜S 2 . The deuterium excess values had no significant temporal variation, while it spatially increased gradually with the river levels. The slope and intercept of water line in this river were smaller than that of the local meteoric water line, suggesting that precipitation was the primary water source for this river. At the seasonal scale, both δD and δ 18 O were significantly negatively correlated with water temperature (δD: r=-0.92; δ 18 O: r=-0.88) and δ 18 O was negatively correlated with altitude (r=-0.96). At spatial scale, δ 18 O had a significantly positive correlation with water temperature. The δD and δ 18 O had negative correlation with precipitation, but being not statistically significant.

Assessment of environmentally friendly fuel emissions from in-use vehicle exhaust: low-blend iso-stoichiometric GEM mixture as example.

PubMed

Schifter, Isaac; Díaz-Gutiérrez, Luis; Rodríguez-Lara, René; González-Macías, Carmen; González-Macías, Uriel

2017-05-01

Gasoline-ethanol-methanol fuel blends were formulated with the same stoichiometric air-to-fuel ratio and volumetric energy concentration as any binary ethanol-gasoline blend. When the stoichiometric blends operated in a vehicle, the time period, injector voltage, and pressure for each fuel injection event in the engine corresponded to a given stoichiometric air-to-fuel ratio, and the load was essentially constant. Three low oxygen content iso-stoichiometric ternary gasoline-ethanol-methanol fuel blends were prepared, and the properties were compared with regular-type fuel without added oxygen. One of the ternary fuels was tested using a fleet of in-use vehicles for15 weeks and compared to neat gasoline without oxygenated compounds as a reference. Only a small number of publications have compared these ternary fuels in the same engine, and little data exist on the performance and emissions of in-use spark-ignition engines. The total hydrocarbon emissions observed was similar in both fuels, in addition to the calculated ozone forming potential of the tailpipe and evaporative emissions. In ozone non-attainment areas, the original purpose for oxygenate gasolines was to decrease carbon monoxide emissions. The results suggest that the strategy is less effective than expected because there still exist a great number of vehicles that have suffered the progressive deterioration of emissions and do not react to oxygenation, while new vehicles are equipped with sophisticated air/fuel control systems, and oxygenation does not improve combustion because the systems adjust the stoichiometric point, making it insensitive to the origin of the added excess oxygen (fuel or excess air). Graphical abstract Low level ternary blend of gasoline-ethanol-methanol were prepared with the same stoichiometric air-fuel ratio and volumetric energy concentration, based on the volumetric energy density of the pre-blended components. Exhaust and evaporative emissions was compared with a blend having no oxygen in a fleet of 12 in-use vehicles. Vehicles that had suffer a normal deterioration of emissions and do not react to oxygenation, and new vehicles with more sophisticated air/fuel control systems do not improve combustion.

Modeling Corneal Oxygen with Scleral Gas Permeable Lens Wear.

PubMed

Compañ, Vicente; Aguilella-Arzo, Marcel; Edrington, Timothy B; Weissman, Barry A

2016-11-01

The main goal of this current work is to use an updated calculation paradigm, and updated boundary conditions, to provide theoretical guidelines to assist the clinician whose goal is to improve his or her scleral gas permeable (GP) contact lens wearing patients' anterior corneal oxygen supply. Our model uses a variable value of corneal oxygen consumption developed through Monod equations that disallows negative oxygen tensions within the stroma to predict oxygen tension at the anterior corneal surface of scleral GP contact lens wearing eyes, and to describe oxygen tension and flux profiles, for various boundary conditions, through the lens, tears, and cornea. We use several updated tissue and boundary parameters in our model. Tear exchange with GP scleral lenses is considered nonexistent in this model. The majority of current scleral GP contact lenses should produce some levels of corneal hypoxia under open eye conditions. Only lenses producing the thinnest of tear vaults should result in anterior corneal surface oxygen tensions greater than a presumed critical oxygen tension of 100 mmHg. We also find that corneal oxygen tension and flux are each more sensitive to modification in tear vault than to changes in lens oxygen permeability, within the ranges of current clinical manipulation. Our study suggests that clinicians would be prudent to prescribe scleral GP lenses manufactured from higher oxygen permeability materials and especially to fit without excessive corneal clearance.

Triple oxygen isotope composition of leaf waters in Mpala, central Kenya

NASA Astrophysics Data System (ADS)

Li, Shuning; Levin, Naomi E.; Soderberg, Keir; Dennis, Kate J.; Caylor, Kelly K.

2017-06-01

Variations in triple oxygen isotopes have been used in studies of atmospheric photochemistry, global productivity and increasingly in studies of hydroclimate. Understanding the distribution of triple oxygen isotopes in plant waters is critical to studying the fluxes of oxygen isotopes between the atmosphere and hydrosphere, in which plants play an important role. In this paper we report triple oxygen isotope data for stem and leaf waters from Mpala, Kenya and explore how Δ17 O, the deviation from an expected relationship between 17O /16O and 18O /16O ratios, in plant waters vary with respect to relative humidity and deuterium excess (d-excess). We observe significant variation in Δ17 O among waters in leaves and stems from a single plant (up to 0.16‰ range in Δ17 O in leaf water in a plant over the course of a signal day), which correlates to changes in relative humidity. A steady state model for evaporation in leaf water reproduces the majority of variation in Δ17 O and d-excess we observed in leaf waters, except for samples that were collected in the morning, when relative humidity is high and the degree of fractionation in the system is minimal. The data and the steady state model indicate that the slope, λtransp, that links δ17 O and δ18 O values of stem and leaf waters and characterizes the fractionation during transpiration, is strongly influenced by the isotopic composition of ambient vapor when relative humidity is high. We observe a strong, positive relationship between d-excess and Δ17 O, with a slope 2.2 ± 0.2 per meg ‰-1, which is consistent with the observed relationship in tropical rainfall and in water in an evaporating open pan. The strong linear relationship between d-excess and Δ17 O should be typical for any process involving evaporation or any other fractionation that is governed by kinetic effects.

Analysis of alpha hemoglobin stabilizing protein overexpression in murine β-thalassemia

PubMed Central

Nasimuzzaman, Md; Khandros, Eugene; Wang, Xiaomei; Kong, Yi; Zhao, Huifen; Weiss, David; Rivella, Stefano; Weiss, Mitchell J.; Persons, Derek A.

2013-01-01

Excess free α-globin is cytotoxic and contributes to the pathophysiology of β-thalassemia. Alpha hemoglobin stabilizing protein (AHSP) is a molecular chaperone that binds free α-globin to promote its folding and inhibit its ability to produce damaging reactive oxygen species. Reduced AHSP levels correlate with increased severity of β-thalassemia in some human cohorts, but causal mechanistic relationships are not established for these associations. We used transgenic and lentiviral gene transfer methods to investigate whether supraphysiologic AHSP levels could mitigate the severity of β-thalassemia intermedia by providing an increased sink for the excess pool of α-globin chains. We tested wild-type AHSP and two mutant versions with amino acid substitutions that confer 3- or 13-fold higher affinity for α-globin. Erythroid overexpression of these AHSP proteins up to 11-fold beyond endogenous levels had no major effects on hematologic parameters in β-thalassemic animals. Our results demonstrate that endogenous AHSP is not limiting for α-globin detoxification in a murine model of β-thalassemia. PMID:20815047

Method for preparing high purity vanadium

DOEpatents

Schmidt, Frederick; Carlson, O. Norman

1986-09-09

A method for preparing high purity vanadium having a low silicon content has been developed. Vanadium pentoxide is reduced with a stoichiometric, or slightly deficient amount of aluminum to produce a vanadium-aluminum alloy containing an excess of oxygen. Silicon is removed by electron-beam melting the alloy under oxidizing conditions to promote the formation of SiO which is volatile at elevated temperatures. Excess oxygen is removed by heating the alloy in the presence of calcium metal to form calcium oxide.

Method for preparing high purity vanadium

DOEpatents

Schmidt, F.; Carlson, O.N.

1984-05-16

A method for preparing high purity vanadium having a low silicon content has been developed. Vanadium pentoxide is reduced with a stoichiometric, or slightly deficient amount of aluminum to produce a vanadium-aluminum alloy containing an excess of oxygen. Silicon is removed by electron-beam melting the alloy under oxidizing conditions to promote the formation of SiO which is volatile at elevated temperatures. Excess oxygen is removed by heating the alloy in the presence of calcium metal to form calcium oxide.

Mechanisms Underlying Endothelin-1 Level Elevations Caused by Excessive Fluoride Exposure.

PubMed

Sun, Liyan; Gao, Yanhui; Zhang, Wei; Liu, Xiaona; Li, Bingyun; Cui, Xiaohui; Sun, Dianjun

2016-01-01

To explore the mechanisms underlying endothelin-1 (ET-1) elevations induced by excessive fluoride exposure. We measured serum and bone fluoride ion content and plasma ET-1 levels and compared these parameters among different groups in an animal model. We also observed morphological changes in the aorta and endothelium of rabbits. In cell experiments, human umbilical vein endothelial cells (HUVECs) were treated with varying concentrations of NaF for 24h, with or without 10 µM U0126 pretreatment for 1 h. ET-1 levels in culture fluid and intracellular reactive oxygen species (ROS) levels, as well as ET1 gene, endothelin-converting enzyme-1 (ECE-1), extracellular signal-regulating kinase 1/2 (ERK1/2), pERK1/2 expression levels and RAS activation were measured and compared among the groups. Plasma ET-1 levels of rabbits increased significantly in fluorinated groups compared with those in the control group. The rabbit thoracic aortas became slightly hardened in fluorinated groups compared with those in the control group, and some vacuoles were present in the endothelial cell cytoplasm of the rabbits in fluorinated groups. In our cell experiments, ET1 gene and ECE-1 expression levels in HUVECs and ET-1 expression levels in the cell culture supernatants increased significantly in some experimental groups compared with those in the control group. These trends paralleled the changes in intracellular ROS levels, RAS activation, and the pERK1/2-to-ERK1/2 ratio. After U0126 was added, ECE-1 expression and ET-1 levels decreased significantly. Excessive fluoride exposure leads to characteristic endothelial damage (vacuoles), thoracic aorta hardening, and plasma ET-1 level elevations in rabbits. In addition, the ROS-RAS-MEK1/2-pERK1/2/ERK1/2 pathway plays a crucial-and at least partial-role in ET-1 over-expression, which is promoted by excessive fluoride exposure. © 2016 The Author(s) Published by S. Karger AG, Basel.

Zeaxanthin Binds to Light-Harvesting Complex Stress-Related Protein to Enhance Nonphotochemical Quenching in Physcomitrella patens[W

PubMed Central

Pinnola, Alberta; Dall’Osto, Luca; Gerotto, Caterina; Morosinotto, Tomas; Bassi, Roberto; Alboresi, Alessandro

2013-01-01

Nonphotochemical quenching (NPQ) dissipates excess energy to protect the photosynthetic apparatus from excess light. The moss Physcomitrella patens exhibits strong NPQ by both algal-type light-harvesting complex stress-related (LHCSR)–dependent and plant-type S subunit of Photosystem II (PSBS)-dependent mechanisms. In this work, we studied the dependence of NPQ reactions on zeaxanthin, which is synthesized under light stress by violaxanthin deepoxidase (VDE) from preexisting violaxanthin. We produced vde knockout (KO) plants and showed they underwent a dramatic reduction in thermal dissipation ability and enhanced photoinhibition in excess light conditions. Multiple mutants (vde lhcsr KO and vde psbs KO) showed that zeaxanthin had a major influence on LHCSR-dependent NPQ, in contrast with previous reports in Chlamydomonas reinhardtii. The PSBS-dependent component of quenching was less dependent on zeaxanthin, despite the near-complete violaxanthin to zeaxanthin exchange in LHC proteins. Consistent with this, we provide biochemical evidence that native LHCSR protein binds zeaxanthin upon excess light stress. These findings suggest that zeaxanthin played an important role in the adaptation of modern plants to the enhanced levels of oxygen and excess light intensity of land environments. PMID:24014548

Zeaxanthin binds to light-harvesting complex stress-related protein to enhance nonphotochemical quenching in Physcomitrella patens.

PubMed

Pinnola, Alberta; Dall'Osto, Luca; Gerotto, Caterina; Morosinotto, Tomas; Bassi, Roberto; Alboresi, Alessandro

2013-09-01

Nonphotochemical quenching (NPQ) dissipates excess energy to protect the photosynthetic apparatus from excess light. The moss Physcomitrella patens exhibits strong NPQ by both algal-type light-harvesting complex stress-related (LHCSR)-dependent and plant-type S subunit of Photosystem II (PSBS)-dependent mechanisms. In this work, we studied the dependence of NPQ reactions on zeaxanthin, which is synthesized under light stress by violaxanthin deepoxidase (VDE) from preexisting violaxanthin. We produced vde knockout (KO) plants and showed they underwent a dramatic reduction in thermal dissipation ability and enhanced photoinhibition in excess light conditions. Multiple mutants (vde lhcsr KO and vde psbs KO) showed that zeaxanthin had a major influence on LHCSR-dependent NPQ, in contrast with previous reports in Chlamydomonas reinhardtii. The PSBS-dependent component of quenching was less dependent on zeaxanthin, despite the near-complete violaxanthin to zeaxanthin exchange in LHC proteins. Consistent with this, we provide biochemical evidence that native LHCSR protein binds zeaxanthin upon excess light stress. These findings suggest that zeaxanthin played an important role in the adaptation of modern plants to the enhanced levels of oxygen and excess light intensity of land environments.

Singlet oxygen-dependent translational control in the tigrina-d.12 mutant of barley.

PubMed

Khandal, Dhriti; Samol, Iga; Buhr, Frank; Pollmann, Stephan; Schmidt, Holger; Clemens, Stephan; Reinbothe, Steffen; Reinbothe, Christiane

2009-08-04

The tigrina (tig)-d.12 mutant of barley is impaired in the negative control limiting excess protochlorophyllide (Pchlide) accumulation in the dark. Upon illumination, Pchlide operates as photosensitizer and triggers singlet oxygen production and cell death. Here, we show that both Pchlide and singlet oxygen operate as signals that control gene expression and metabolite accumulation in tig-d.12 plants. In vivo labeling, Northern blotting, polysome profiling, and protein gel blot analyses revealed a selective suppression of synthesis of the small and large subunits of ribulose-1,5-bisphosphate carboxylase/oxygenase (RBCSs and RBCLs), the major light-harvesting chlorophyll a/b-binding protein of photosystem II (LHCB2), as well as other chlorophyll-binding proteins, in response to singlet oxygen. In part, these effects were caused by an arrest in translation initiation of photosynthetic transcripts at 80S cytoplasmic ribosomes. The observed changes in translation correlated with a decline in the phosphorylation level of ribosomal protein S6. At later stages, ribosome dissociation occurred. Together, our results identify translation as a major target of singlet oxygen-dependent growth control and cell death in higher plants.

Exposure to hyperoxia in the neonatal period alters bone marrow function

USDA-ARS?s Scientific Manuscript database

Oxygen is often life saving in preterm infants, however, excessive exposure may lead to blood vessel and tissue injury in the lung and retina. Oxygen-treated neonates often exhibit bone marrow (BM) suppression requiring blood product transfusions. However, we do not know whether oxygen is directly t...

Excess Iodide Induces an Acute Inhibition of the Sodium/Iodide Symporter in Thyroid Male Rat Cells by Increasing Reactive Oxygen Species

PubMed Central

Arriagada, Alejandro A.; Albornoz, Eduardo; Opazo, Ma. Cecilia; Becerra, Alvaro; Vidal, Gonzalo; Fardella, Carlos; Michea, Luis; Carrasco, Nancy; Simon, Felipe; Elorza, Alvaro A.; Bueno, Susan M.; Kalergis, Alexis M.

2015-01-01

Na+/I− symporter (NIS) mediates iodide (I−) uptake in the thyroid gland, the first and rate-limiting step in the biosynthesis of the thyroid hormones. The expression and function of NIS in thyroid cells is mainly regulated by TSH and by the intracellular concentration of I−. High doses of I− for 1 or 2 days inhibit the synthesis of thyroid hormones, a process known as the Wolff-Chaikoff effect. The cellular mechanisms responsible for this physiological response are mediated in part by the inhibition of I− uptake through a reduction of NIS expression. Here we show that inhibition of I− uptake occurs as early as 2 hours or 5 hours after exposure to excess I− in FRTL-5 cells and the rat thyroid gland, respectively. Inhibition of I− uptake was not due to reduced NIS expression or altered localization in thyroid cells. We observed that incubation of FRTL-5 cells with excess I− for 2 hours increased H2O2 generation. Furthermore, the inhibitory effect of excess I− on NIS-mediated I− transport could be recapitulated by H2O2 and reverted by reactive derived oxygen species scavengers. The data shown here support the notion that excess I− inhibits NIS at the cell surface at early times by means of a posttranslational mechanism that involves reactive derived oxygen species. PMID:25594695

Citrate gel synthesis of aluminum-doped lithium lanthanum titanate solid electrolyte for application in organic-type lithium-oxygen batteries

NASA Astrophysics Data System (ADS)

Le, Hang T. T.; Kalubarme, Ramchandra S.; Ngo, Duc Tung; Jang, Seong-Yong; Jung, Kyu-Nam; Shin, Kyoung-Hee; Park, Chan-Jin

2015-01-01

Aluminium doped lithium lanthanum titanate (A-LLTO) powders with various excess Li2O content are synthesized using a simple citrate gel method. The obtained A-LLTO powders show an agglomerated form, composed of nano-sized particles of 20-50 nm. The morphology and conductivity of the A-LLTO ceramics are largely affected by the content of excess Li2O. The highest total ionic conductivity of 3.17 × 10-4 S cm-1 is achieved for the A-LLTO sample containing 20% excess Li2O, exhibiting a vacancy content of 6%, and a total activation energy of 0.358 eV. The A-LLTO can act as a membrane to protect lithium metal from oxygen and other contaminants diffused through the oxygen electrode part. The Li-O2 cell employing the A-LLTO solid electrolyte shows a good cycle life of longer than 100 discharge-charge cycles, under the constant capacity mode of 300 mAh g-1.

Effect of excess iron on oxidative stress and gluconeogenesis through hepcidin during mitochondrial dysfunction.

PubMed

Lee, Hyo Jung; Choi, Joo Sun; Lee, Hye Ja; Kim, Won-Ho; Park, Sang Ick; Song, Jihyun

2015-12-01

Excessive tissue iron levels are a risk factor for insulin resistance and type 2 diabetes, which are associated with alterations in iron metabolism. However, the mechanisms underlying this association are not well understood. This study used human liver SK-HEP-1 cells to examine how excess iron induces mitochondrial dysfunction and how hepcidin controls gluconeogenesis. Excess levels of reactive oxygen species (ROS) and accumulated iron due to iron overload induced mitochondrial dysfunction, leading to a decrease in cellular adenosine triphosphate content and cytochrome c oxidase III expression, with an associated increase in gluconeogenesis. Disturbances in mitochondrial function caused excess iron deposition and unbalanced expression of iron metabolism-related proteins such as hepcidin, ferritin H and ferroportin during the activation of p38 mitogen-activated protein kinase (MAPK) and CCAAT/enhancer-binding protein alpha (C/EBPα), which are responsible for increased phosphoenolpyruvate carboxykinase expression. Desferoxamine and n-acetylcysteine ameliorated these deteriorations by inhibiting p38 MAPK and C/EBPα activity through iron chelation and ROS scavenging activity. Based on experiments using hepcidin shRNA and hepcidin overexpression, the activation of hepcidin affects ROS generation and iron deposition, which disturbs mitochondrial function and causes an imbalance in iron metabolism and increased gluconeogenesis. Repression of hepcidin activity can reverse these changes. Our results demonstrate that iron overload is associated with mitochondrial dysfunction and that together they can cause abnormal hepatic gluconeogenesis. Hepcidin expression may modulate this disorder by regulating ROS generation and iron deposition. Copyright © 2015 Elsevier Inc. All rights reserved.

Enhanced thermoelectric properties via oxygen non-stoichiometry in La2NiO4 and SrTiO3

NASA Astrophysics Data System (ADS)

Pardo, Victor; Botana, Antia S.; Bach, Paul M.; Leboran, Victor; Rivadulla, Francisco; Baldomir, Daniel

2013-03-01

We present the results of transport properties calculations and experiments on various oxides. A large enhancement of the thermoelectric properties is predicted[1] via ab initio calculations for La2NiO4+δ, with electronic-only thermoelectric figure of merit (zT) values exceeding unity for oxygen excess δ <= 0.10. The effects of lattice strain (caused, e.g. by growth of thin films on different substrates) enhance even further the thermoelectric response. A similar result is obtained at very low electron-doping in bulk SrTiO3 via oxygen removal. This is analyzed experimentally via thermal annealing that depletes oxygen (~ 1 oxygen vacancy per 106 unit cells). In both these systems, the increase in conductivity reached in the metallic limit retains a large thermopower, with the corresponding enhancement of zT . In the case of SrTiO3, experiments indicate[2] that such a small oxygen vacancy level reduces drastically the thermal conductivity by introducing random scattering centers. In the talk, we will discuss the electronic structure origin of the enhancement of the thermoelectric response and how this can be tuned. Results are general and applicable to other non-stoichiometric oxides.

Experimental Evaluation of a Subscale Gaseous Hydrogen/gaseous Oxygen Coaxial Rocket Injector

NASA Technical Reports Server (NTRS)

Smith, Timothy D.; Klem, Mark D.; Breisacher, Kevin J.; Farhangi, Shahram; Sutton, Robert

2002-01-01

The next generation reusable launch vehicle may utilize a Full-Flow Stage Combustion (FFSC) rocket engine cycle. One of the key technologies required is the development of an injector that uses gaseous oxygen and gaseous hydrogen as propellants. Gas-gas propellant injection provides an engine with increased stability margin over a range of throttle set points. This paper summarizes an injector design and testing effort that evaluated a coaxial rocket injector for use with gaseous oxygen and gaseous hydrogen propellants. A total of 19 hot-fire tests were conducted up to a chamber pressure of 1030 psia, over a range of 3.3 to 6.7 for injector element mixture ratio. Post-test condition of the hardware was also used to assess injector face cooling. Results show that high combustion performance levels could be achieved with gas-gas propellants and there were no problems with excessive face heating for the conditions tested.

Climate change and temperature-dependent biogeography: oxygen limitation of thermal tolerance in animals.

PubMed

Pörtner, H O

2001-04-01

Recent years have shown a rise in mean global temperatures and a shift in the geographical distribution of ectothermic animals. For a cause and effect analysis the present paper discusses those physiological processes limiting thermal tolerance. The lower heat tolerance in metazoa compared with unicellular eukaryotes and bacteria suggests that a complex systemic rather than molecular process is limiting in metazoa. Whole-animal aerobic scope appears as the first process limited at low and high temperatures, linked to the progressively insufficient capacity of circulation and ventilation. Oxygen levels in body fluids may decrease, reflecting excessive oxygen demand at high temperatures or insufficient aerobic capacity of mitochondria at low temperatures. Aerobic scope falls at temperatures beyond the thermal optimum and vanishes at low or high critical temperatures when transition to an anaerobic mitochondrial metabolism occurs. The adjustment of mitochondrial densities on top of parallel molecular or membrane adjustments appears crucial for maintaining aerobic scope and for shifting thermal tolerance. In conclusion, the capacity of oxygen delivery matches full aerobic scope only within the thermal optimum. At temperatures outside this range, only time-limited survival is supported by residual aerobic scope, then anaerobic metabolism and finally molecular protection by heat shock proteins and antioxidative defence. In a cause and effect hierarchy, the progressive increase in oxygen limitation at extreme temperatures may even enhance oxidative and denaturation stress. As a corollary, capacity limitations at a complex level of organisation, the oxygen delivery system, define thermal tolerance limits before molecular functions become disturbed.

Hepatic Flavin-Containing Monooxygenase 3 Enzyme Suppressed by Type 1 Allergy-Produced Nitric Oxide.

PubMed

Tanino, Tadatoshi; Bando, Toru; Komada, Akira; Nojiri, Yukie; Okada, Yuna; Ueda, Yukari; Sakurai, Eiichi

2017-11-01

Flavin-containing monooxygenases (FMOs) are major mammalian non-cytochrome P450 oxidative enzymes. T helper 2 cell-activated allergic diseases produce excess levels of nitric oxide (NO) that modify the functions of proteins. However, it remains unclear whether allergy-induced NO affects the pharmacokinetics of drugs metabolized by FMOs. This study investigated alterations of hepatic microsomal FMO1 and FMO3 activities in type 1 allergic mice and further examined the interaction of FMO1 and FMO3 with allergy-induced NO. Imipramine (IMP; FMO1 substrate) N- oxidation activity was not altered in allergic mice with high serum NO and immunoglobulin E levels. At 7 days after primary sensitization (PS7) or secondary sensitization (SS7), benzydamine (BDZ; FMO1 and FMO3 substrate) N- oxygenation was significantly decreased to 70% of individual controls. The expression levels of FMO1 and FMO3 proteins were not significantly changed in the sensitized mice. Hepatic inducible NO synthase (iNOS) mRNA level increased 5-fold and 15-fold in PS7 and SS7 mice, respectively, and hepatic tumor necrosis factor- α levels were greatly enhanced. When a selective iNOS inhibitor was injected into allergic mice, serum NO levels and BDZ N- oxygenation activity returned to control levels. NO directly suppressed BDZ N- oxygenation, which was probably related to FMO3-dependent metabolism in comparison with IMP N- oxidation. In hepatic microsomes from PS7 and SS7 mice, the suppression of BDZ N- oxygenation was restored by ascorbate. Therefore, type 1 allergic mice had differentially suppressed FMO3-dependent BDZ N- oxygenation. The suppression of FMO3 metabolism related to reversible S- nitrosyl modifications of iNOS-derived NO. NO is expected to alter FMO3-metabolic capacity-limited drug pharmacokinetics in humans. Copyright © 2017 by The American Society for Pharmacology and Experimental Therapeutics.

Bedside determination of bicarbonate and base excess, blood oxygen saturation and content, VD/VT, and P50 using a programmable calculator.

PubMed

Wilkinson, P L

1979-06-01

Assessing and modifying oxygen transport are major parts of ICU patient management. Determination of base excess, blood oxygen saturation and content, dead space ventilation, and P50 helps in this management. A program is described for determining these variables using a T1 59 programmable calculator and PC 100A printer. Each variable can be independently calculated without running the whole program. The calculator-printer's small size, low cost, and hard copy printout make it a valuable and versatile tool for calculating physiological variables. The program is easily entered by an stored on magnetic card, and prompts the user to enter the appropriate variables, making is easy to run by untrained personnel.

Influence of oxygen availability on the metabolism and morphology of Yarrowia lipolytica: insights into the impact of glucose levels on dimorphism.

PubMed

Timoumi, Asma; Bideaux, Carine; Guillouet, Stéphane E; Allouche, Yohan; Molina-Jouve, Carole; Fillaudeau, Luc; Gorret, Nathalie

2017-10-01

Dynamic behavior of Yarrowia lipolytica W29 strain under conditions of fluctuating, low, and limited oxygen supply was characterized in batch and glucose-limited chemostat cultures. In batch cultures, transient oscillations between oxygen-rich and -deprived environments induced a slight citric acid accumulation (lower than 29 mg L -1 ). By contrast, no citric acid was detected in continuous fermentations for all stress conditions: full anoxia (zero pO 2 value, 100% N 2 ), limited (zero pO 2 value, 75% of cell needs), and low (pO 2 close to 2%) dissolved oxygen (DO) levels. The macroscopic behavior (kinetic parameters, yields, viability) of Y. lipolytica was not significantly affected by the exposure to DO fluctuations under both modes of culture. Nevertheless, conditions of oxygen limitation resulted in the destabilization of the glucose-limited growth during the continuous cultivations. Morphological responses of Y. lipolytica to DO oscillations were different between batch and chemostat runs. Indeed, a yeast-to-mycelium transition was induced and progressively intensified during the batch fermentations (filamentous subpopulation reaching 74% (v/v)). While, in chemostat bioreactors, the culture consisted mainly of yeast-like cells (mean diameter not exceeding 5.7 μm) with a normal size distribution. During the continuous cultures, growth at low DO concentration did not induce any changes in Y. lipolytica morphology. Dimorphism (up to 80.5% (v/v) of filaments) was only detected under conditions of oxygen limitation in the presence of a residual glucose excess (more than 0.75 g L -1 ). These data suggest an impact of glucose levels on the signaling pathways regulating dimorphic responses in Y. lipolytica.

Online oxygen control for sulfide oxidation in anaerobic treatment of high-sulfate wastewater.

PubMed

Khanal, Samir Kumar; Huang, Ju-Chang

2006-04-01

A new technique for sulfide control was investigated in an upflow-anaerobic filter (UAF) treating high-strength, sulfate-rich wastewater. The technique used periodic oxygen injection using oxidation-reduction potential (ORP) as a controlling parameter to regulate oxygen injection. The UAF was operated at a constant influent total-organic carbon of 6740 mg/L but with different influent sulfates of 1000, 3000, and 6000 mg/L. At 1000 and 3000 mg/L influent sulfates, the produced sulfide did not impose any inhibition to methane-producing bacteria (MPB). However, at 6000 mg/L influent sulfate, the produced dissolved sulfide of 804 mg S/L (free sulfide = 280 mg S/L) severely inhibited the methanogenesis, but not the sulfidogenesis. Upon oxygen injection at elevated ORP of -265 mV, sulfides were almost completely eliminated with a concomitant improvement in methane yield by 46%. If oxygenation was excessive because of an oversetting of ORP, the excess oxygen could be used rapidly by facultative heterotrophs, thereby protecting the MPB from oxygen stress. Regarding online sulfide oxidation, it was found that the biogas and injected oxygen needed to pass through an aqueous layer containing trace metals, which were found to have a significant catalytic effect on abiotic sulfide oxidation.

The Effects: Dead Zones and Harmful Algal Blooms

EPA Pesticide Factsheets

Excess nitrogen and phosphorus can cause algae blooms. The overgrowth of algae consumes oxygen and blocks sunlight from underwater plants. When the algae die, the oxygen in the water is consumed, making it impossible for aquatic life to survive.

Effect of exercise and exogenous glucocorticoid on serum level of intact parathyroid hormone.

PubMed

Tsai, K S; Lin, J C; Chen, C K; Cheng, W C; Yang, C H

1997-11-01

Most previous studies suggest that physical exercise, or physiological response to exercise such as cortisol and adrenaline secretion regulate parathyroid hormone (PTH) secretion in humans. To investigate the effects and possible interaction of exercise and excessive glucocorticoid on PTH secretion, we examined the serum of levels of intact-PTH, cortisol, adrenocorticotrophic hormone (ACTH), calcium, magnesium and phosphorus before and during one-hour of bicycle-ergometric exercise at 60% of maximal oxygen uptake. These exercise tests were performed on eight Chinese male volunteers aged between 20 and 25 years, once with and once without pretreatment with 0.5 mg of dexamethasone taken orally 9.5 hours in advance. The results showed that dexamethasone pretreatment significantly lowered basal levels of cortisol and ACTH, but intact PTH did not change. After 60 minutes of bicycling, intact PTH level increases by 50% of baseline both with and without dexamethasone pretreatment. Serum levels of calcium, corrected for changes in serum albumin concentration, phosphorus and magnesium also increased in both cases. This study demonstrated an increase of intact-PTH with exercise which was not associated with hypocalcemia or hypomagnesemia, and was not altered in the presence of mild exogenous glucocorticoid excess and suppressed endogenous cortisol secretion.

[Gradation in the level of vitamin consumption: possible risk of excessive consumption].

PubMed

Kodentsova, V M

2014-01-01

The ratio between the levels of consumption of certain vitamins and minerals [recommended daily allowance for labelling purposes < maximum supplement levels < tolerable upper intake level (UL) < safe level (limit) of consumption < or = therapeutic dose has been characterized. Vitamin A and beta-carotene maximum supplement levels coincides with UL, and recommended daily allowance for these micronutrients coincides with the maximal level of consumption through dietary supplements and/or multivitamins. Except for vitamin A and beta-carotene recommended daily allowance for other vitamins adopted in Russia are considerably lower than the upper safe level of consumption. For vitamin A and beta-carotene there is a potential risk for excess consumption. According to the literature data (meta-analysis) prolonged intake of high doses of antioxidant vitamins (above the RDA) both alone and in combination with two other vitamins or vitamin C [> 800 microg (R.E.) of vitamin A, > 9.6 mg of beta-carotene, > 15 mg (T.E.) of vitamin E] do not possess preventive effects and may be harmful with unwanted consequences to health, especially in well-nourished populations, persons having risk of lung cancer (smokers, workers exposed to asbestos), in certain conditions (in the atmosphere with high oxygen content, hyperoxia, oxygen therapy). Proposed mechanisms of such action may be due to the manifestation of prooxidant action when taken in high doses, shifting balance with other important natural antioxidants, their displacement (substitution), interference with the natural defense mechanisms. Athletes are the population group that requires attention as used antioxidant vitamins A, C, E, both individually and in combination in extremely high doses. In summary, it should be noted that intake of physiological doses which are equivalent to the needs of the human organism, as well as diet inclusion of fortified foods not only pose no threat to health, but will bring undoubted benefits, filling the existing lack of vitamins in the ration.

The ejector flowmeter as air/oxygen mixing device. An apparatus providing gas mixtures with adjustable oxygen content for high-flow humidification systems.

PubMed

Christensen, K N; Waaben, J; Jørgensen, S

1980-04-01

The ejector flowmeter is constructed for continuous removal of excess gas from anaesthetic circuits. This instrument can be used as an air/oxygen mixing device for high-flow humidification systems in wards where compressed air is not available. Pure oxygen is used as driving gas through the ejector. A nomogram has been constructed to show the relationship between oxygen driving pressure, inlet of air to the flowmeter, FIO2 and total outflow.

Oxygen-induced recombination centers in as-grown Czochralski silicon crystals

NASA Technical Reports Server (NTRS)

Nauka, K.; Gatos, H. C.; Lagowski, J.

1983-01-01

Simultaneous quantitative microprofiles of the interstitial oxygen concentration and of the excess carrier lifetime are obtained in Czochralski-grown Si crystals employing double laser absorption scanning. It is found that oxygen concentration maxima and minima along the crystal growth direction coincide with lifetime minima and maxima, respectively. Another finding is that the magnitude of oxygen-induced lifetime changes increases dramatically in going from the center to the periphery of the crystal. The findings discussed imply that 'as-grown' oxygen precipitates figure in lifetime-limiting processes.

Replication of the Apparent Excess Heat Effect in a Light Water-Potassium Carbonate-Nickel Electrolytic Cell

NASA Technical Reports Server (NTRS)

Niedra, Janis M.; Myers, Ira T.; Fralick, Gustave C.; Baldwin, Richard S.

1996-01-01

Replication of experiments claiming to demonstrate excess heat production in light water-Ni-K2CO3 electrolytic cells was found to produce an apparent excess heat of 11 W maximum, for 60 W electrical power into the cell. Power gains range from 1.06 to 1.68. The cell was operated at four different dc current levels plus one pulsed current run at 1 Hz, 10% duty cycle. The 28 liter cell used in these verification tests was on loan from a private corporation whose own tests with similar cells are documented to produce 50 W steady excess heat for a continuous period exceeding hundreds of days. The apparent excess heat can not be readily explained either in terms of nonlinearity of the cell's thermal conductance at a low temperature differential or by thermoelectric heat pumping. However, the present data do admit efficient recombination of dissolved hydrogen-oxygen as an ordinary explanation. Calorimetry methods and heat balance calculations for the verification tests are described. Considering the large magnitude of benefit if this effect is found to be a genuine new energy source, a more thorough investigation of evolved heat in the nickel-hydrogen system in both electrolytic and gaseous loading cells remains warranted.

Organic matters: investigating the sources, transport, and fate of organic matter in Fanno Creek, Oregon

USGS Publications Warehouse

Sobieszczyk, Steven; Keith, Mackenzie K.; Goldman, Jami H.; Rounds, Stewart A.

2015-01-01

The U.S. Geological Survey (USGS), in cooperation with Clean Water Services, recently completed an investigation into the sources, transport, and fate of organic matter in the Fanno Creek watershed. The information provided by this investigation will help resource managers to implement strategies aimed at decreasing the excess supply of organic matter that contributes to low dissolved-oxygen levels in Fanno Creek and downstream in the Tualatin River during summer. This fact sheet summarizes the findings of the investigation.

Intraosseous Erythropoietin for Acute Tissue Protection in Battlefield Casualties Suffering Hypovolemic Shock

DTIC Science & Technology

2015-07-01

excess deficit, likely related to a flow dependent reduction in systemic oxygen consumption (VO2), but this effect was transient attain- ing values... oxygen delivery index; VO2, systemic oxygen consumption index; Hct, hematocrit, PaCO2, arterial PCO2; PETCO2, end-tidal PCO2. Table S1: Effect of...response that enabled maintaining oxygen consumption close to baseline resulting in minimal lactate increases and high resuscitability and survival without

Singlet oxygen-dependent translational control in the tigrina-d.12 mutant of barley

PubMed Central

Khandal, Dhriti; Samol, Iga; Buhr, Frank; Pollmann, Stephan; Schmidt, Holger; Clemens, Stephan; Reinbothe, Steffen; Reinbothe, Christiane

2009-01-01

The tigrina (tig)-d.12 mutant of barley is impaired in the negative control limiting excess protochlorophyllide (Pchlide) accumulation in the dark. Upon illumination, Pchlide operates as photosensitizer and triggers singlet oxygen production and cell death. Here, we show that both Pchlide and singlet oxygen operate as signals that control gene expression and metabolite accumulation in tig-d.12 plants. In vivo labeling, Northern blotting, polysome profiling, and protein gel blot analyses revealed a selective suppression of synthesis of the small and large subunits of ribulose-1,5-bisphosphate carboxylase/oxygenase (RBCSs and RBCLs), the major light-harvesting chlorophyll a/b-binding protein of photosystem II (LHCB2), as well as other chlorophyll-binding proteins, in response to singlet oxygen. In part, these effects were caused by an arrest in translation initiation of photosynthetic transcripts at 80S cytoplasmic ribosomes. The observed changes in translation correlated with a decline in the phosphorylation level of ribosomal protein S6. At later stages, ribosome dissociation occurred. Together, our results identify translation as a major target of singlet oxygen-dependent growth control and cell death in higher plants. PMID:19620736

An Update on Oxidative Damage to Spermatozoa and Oocytes.

PubMed

Opuwari, Chinyerum S; Henkel, Ralf R

2016-01-01

On the one hand, reactive oxygen species (ROS) are mandatory mediators for essential cellular functions including the function of germ cells (oocytes and spermatozoa) and thereby the fertilization process. However, the exposure of these cells to excessive levels of oxidative stress by too high levels of ROS or too low levels of antioxidative protection will render these cells dysfunctional thereby failing the fertilization process and causing couples to be infertile. Numerous causes are responsible for the delicate bodily redox system being out of balance and causing disease and infertility. Many of these causes are modifiable such as lifestyle factors like obesity, poor nutrition, heat stress, smoking, or alcohol abuse. Possible correctable measures include foremost lifestyle changes, but also supplementation with antioxidants to scavenge excessive ROS. However, this should only be done after careful examination of the patient and establishment of the individual bodily antioxidant needs. In addition, other corrective measures include sperm separation for assisted reproductive techniques. However, these techniques have to be carried out very carefully as they, if applied wrongly, bear risks of generating ROS damaging the germ cells and preventing fertilization.

An Update on Oxidative Damage to Spermatozoa and Oocytes

PubMed Central

Opuwari, Chinyerum S.; Henkel, Ralf R.

2016-01-01

On the one hand, reactive oxygen species (ROS) are mandatory mediators for essential cellular functions including the function of germ cells (oocytes and spermatozoa) and thereby the fertilization process. However, the exposure of these cells to excessive levels of oxidative stress by too high levels of ROS or too low levels of antioxidative protection will render these cells dysfunctional thereby failing the fertilization process and causing couples to be infertile. Numerous causes are responsible for the delicate bodily redox system being out of balance and causing disease and infertility. Many of these causes are modifiable such as lifestyle factors like obesity, poor nutrition, heat stress, smoking, or alcohol abuse. Possible correctable measures include foremost lifestyle changes, but also supplementation with antioxidants to scavenge excessive ROS. However, this should only be done after careful examination of the patient and establishment of the individual bodily antioxidant needs. In addition, other corrective measures include sperm separation for assisted reproductive techniques. However, these techniques have to be carried out very carefully as they, if applied wrongly, bear risks of generating ROS damaging the germ cells and preventing fertilization. PMID:26942204

Oxygen and U-Th isotopes and the timescales of hydrothermal exchange and melting in granitoid wall rocks at Mount Mazama, Crater Lake, Oregon

USGS Publications Warehouse

Ankney, Meagan E.; Bacon, Charles R.; Valley, John W.; Beard, Brian L.; Johnson, Clark M.

2017-01-01

We report new whole rock U-Th and in-situ oxygen isotope compositions for partially melted (0–50 vol% melt), low-δ18O Pleistocene granitoid blocks ejected during the ∼7.7 ka caldera-forming eruption of Mt. Mazama (Crater Lake, Oregon). The blocks are interpreted to represent wall rocks of the climactic magma chamber that, prior to eruption, experienced variable amounts of exchange with meteoric hydrothermal fluids and subsequent partial melting. U-Th and oxygen isotope results allow us to examine the timescales of hydrothermal circulation and partial melting, and provide an “outside in” perspective on the buildup to the climactic eruption of Mt. Mazama. Oxygen isotope compositions measured in the cores and rims of individual quartz (n = 126) and plagioclase (n = 91) crystals, and for transects across ten quartz crystals, document zonation in quartz (Δ18OCore-Rim ≤ 0.1–5.5‰), but show homogeneity in plagioclase (Δ18OCore-Rim ≤ ±0.8‰). We propose that oxygen isotope zonation in quartz records hydrothermal exchange followed by high-temperature exchange in response to partial melting caused by injection of basaltic to andesitic recharge magma into the deeper portions of the chamber. Results of modeling of oxygen diffusion in quartz indicates that hydrothermal exchange in quartz occurred over a period of ∼1000–63,000 years. Models also suggest that the onset of melting of the granitoids occurred a minimum of ∼10–200 years prior to the Mazama climactic eruption, an inference which is broadly consistent with results for magnetite homogenization and for Zr diffusion in melt previously reported by others.Uranium-thorium isotope compositions of most granitoid blocks are in 238U excess, and are in agreement with a 238U enriched array previously measured for volcanic rocks at Mt. Mazama. Uranium excess in the granitoids is likely due to enrichment via hydrothermal circulation, given their low δ18O values. The sample with the highest U excess (≥5.8%) also has the most 18O isotope depletion (average δ18Oplag = −4.0‰). The granitoids are a probable assimilant and source of U excess in volcanic rocks from Mt. Mazama. Two granitoids have Th excess and low δ18O values, interpreted to record leaching of U during hydrothermal alteration. A U-Th isochron based on the U excess array of the granitoids and volcanic rocks indicates that hydrothermal circulation initiated ∼40–75 kyrs before the climactic eruption, potentially marking the initiation of a persistent upper-crustal magma chamber. The U-Th ages are consistent with the maximum timescales inferred for hydrothermal alteration based on oxygen isotope zoning in quartz.

[Oxidative stress and antioxitant therapy of chronic periodontitis].

PubMed

Shen, Y X; Guo, S J; Wu, Y F

2016-07-01

Chronic periodontitis is a progressive, infectious inflammation disease, caused by the dysbiosis of oral resident flora, leading to the destruction of periodontium. The onset of pathogenic microorganisms is the etiological factor of periodontitis, while the immuno-inflammatory response affects the progression of the disease. Under chronic periodontitis, oxidative stress occurs when excessive reactive oxygen species are produced and exceed the compensative capacity of the organism. Oxidative stress leads to the destruction of periodontium, in a direct way(damaging the biomolecule) or an indirect way(enhancing the produce of inflammatory cytokine and destructive enzymes). Therefore, as the antagonist of the reactive oxygen species, antioxidants may be helpful to treat the chronic periodontitis. This paper reviewed relevant literatures about the destructive role of excessive reactive oxygen species and protective role of antioxidants in chronic periodontitis.

40 CFR 63.1203 - What are the standards for hazardous waste incinerators that are effective until compliance with...

Code of Federal Regulations, 2010 CFR

2010-07-01

... monitoring system), dry basis, corrected to 7 percent oxygen, and reported as propane; (6) Hydrochloric acid... hydrochloric acid equivalents, dry basis and corrected to 7 percent oxygen; and (7) Particulate matter in... oxygen, and reported as propane; (6) Hydrochloric acid and chlorine gas in excess of 21 parts per million...

40 CFR 63.1203 - What are the standards for hazardous waste incinerators that are effective until compliance with...

Code of Federal Regulations, 2011 CFR

2011-07-01

... monitoring system), dry basis, corrected to 7 percent oxygen, and reported as propane; (6) Hydrochloric acid... hydrochloric acid equivalents, dry basis and corrected to 7 percent oxygen; and (7) Particulate matter in... oxygen, and reported as propane; (6) Hydrochloric acid and chlorine gas in excess of 21 parts per million...

40 CFR 63.1203 - What are the standards for hazardous waste incinerators that are effective until compliance with...

Code of Federal Regulations, 2012 CFR

2012-07-01

... monitoring system), dry basis, corrected to 7 percent oxygen, and reported as propane; (6) Hydrochloric acid... hydrochloric acid equivalents, dry basis and corrected to 7 percent oxygen; and (7) Particulate matter in... oxygen, and reported as propane; (6) Hydrochloric acid and chlorine gas in excess of 21 parts per million...

Characterizing Myeloid Cell Activation in NF1 Vasculopathy

DTIC Science & Technology

2017-07-01

stimulation of its receptor (CCR2) and the generation of reactive oxygen species, which are generated in excessive quantities by neurofibromin-deficient...macrophages via monocyte chemotactic peptide-1 (MCP-1) stimulation of its receptor (CCR2) and the generation of reactive oxygen species, which are...neurofibromatosis; stenosis; aneurysm; MCP-1; CCR2; reactive oxygen species; superoxide; macrophages; monocytes; arteries; cardiovascular disease Major

PO2 cycling reduces diaphragm fatigue by attenuating ROS formation.

PubMed

Zuo, Li; Diaz, Philip T; Chien, Michael T; Roberts, William J; Kishek, Juliana; Best, Thomas M; Wagner, Peter D

2014-01-01

Prolonged muscle exposure to low PO2 conditions may cause oxidative stress resulting in severe muscular injuries. We hypothesize that PO2 cycling preconditioning, which involves brief cycles of diaphragmatic muscle exposure to a low oxygen level (40 Torr) followed by a high oxygen level (550 Torr), can reduce intracellular reactive oxygen species (ROS) as well as attenuate muscle fatigue in mouse diaphragm under low PO2. Accordingly, dihydrofluorescein (a fluorescent probe) was used to monitor muscular ROS production in real time with confocal microscopy during a lower PO2 condition. In the control group with no PO2 cycling, intracellular ROS formation did not appear during the first 15 min of the low PO2 period. However, after 20 min of low PO2, ROS levels increased significantly by ∼30% compared to baseline, and this increase continued until the end of the 30 min low PO2 condition. Conversely, muscles treated with PO2 cycling showed a complete absence of enhanced fluorescence emission throughout the entire low PO2 period. Furthermore, PO2 cycling-treated diaphragm exhibited increased fatigue resistance during prolonged low PO2 period compared to control. Thus, our data suggest that PO2 cycling mitigates diaphragm fatigue during prolonged low PO2. Although the exact mechanism for this protection remains to be elucidated, it is likely that through limiting excessive ROS levels, PO2 cycling initiates ROS-related antioxidant defenses.

Discharge and aftercare in chronic lung disease of the newborn.

PubMed

Primhak, R A

2003-04-01

This article deals with the discharge planning and continuing care of babies with chronic lung disease of the newborn (CLD), especially those with a continuing oxygen requirement, with some reference to longer term outcome. The pattern of CLD has changed since early descriptions, and the most useful definition for persisting morbidity in a baby with lung disease is a continuing oxygen requirement beyond 36 weeks post-menstrual age. Long-term oxygen therapy to maintain oxygen saturation at a mean of 95% or more and prevent levels below 90% is the cornerstone of management, and with adequate oxygen therapy the excess mortality previously reported in CLD can largely be avoided. Care must be given to the method of assessing oxygen saturation: overnight monitoring using appropriate recording devices is recommended. Exposure to respiratory viruses should be minimized where possible. Metabolic requirements are increased, but if efforts are made to maintain adequate energy input the long-term outlook for catch-up growth in height is good. Respiratory morbidity is increased in early life, but this improves in later childhood, along with lung function and exercise tolerance. Although respiratory symptoms should be treated as they arise, there is no evidence for long-term benefit from any pharmacological intervention in CLD.

Overexpression of mitochondrial sirtuins alters glycolysis and mitochondrial function in HEK293 cells.

PubMed

de Moura, Michelle Barbi; Uppala, Radha; Zhang, Yuxun; Van Houten, Bennett; Goetzman, Eric S

2014-01-01

SIRT3, SIRT4, and SIRT5 are mitochondrial deacylases that impact multiple facets of energy metabolism and mitochondrial function. SIRT3 activates several mitochondrial enzymes, SIRT4 represses its targets, and SIRT5 has been shown to both activate and repress mitochondrial enzymes. To gain insight into the relative effects of the mitochondrial sirtuins in governing mitochondrial energy metabolism, SIRT3, SIRT4, and SIRT5 overexpressing HEK293 cells were directly compared. When grown under standard cell culture conditions (25 mM glucose) all three sirtuins induced increases in mitochondrial respiration, glycolysis, and glucose oxidation, but with no change in growth rate or in steady-state ATP concentration. Increased proton leak, as evidenced by oxygen consumption in the presence of oligomycin, appeared to explain much of the increase in basal oxygen utilization. Growth in 5 mM glucose normalized the elevations in basal oxygen consumption, proton leak, and glycolysis in all sirtuin over-expressing cells. While the above effects were common to all three mitochondrial sirtuins, some differences between the SIRT3, SIRT4, and SIRT5 expressing cells were noted. Only SIRT3 overexpression affected fatty acid metabolism, and only SIRT4 overexpression altered superoxide levels and mitochondrial membrane potential. We conclude that all three mitochondrial sirtuins can promote increased mitochondrial respiration and cellular metabolism. SIRT3, SIRT4, and SIRT5 appear to respond to excess glucose by inducing a coordinated increase of glycolysis and respiration, with the excess energy dissipated via proton leak.

Mechanisms of deep benzene oxidation on the Pt(1 1 1) surface using temperature-programmed reaction methods

NASA Astrophysics Data System (ADS)

Marsh, Anderson L.; Gland, John L.

2003-06-01

The catalytic oxidation of benzene on the Pt(1 1 1) surface has been characterized using temperature-programmed reaction spectroscopy (TPRS) over a wide range of benzene and oxygen coverages. Coadsorbed atomic oxygen and benzene are the primary reactants on the surface during the initial oxidation step. Benzene is oxidized over the 300-500 K range to produce carbon dioxide and water. Carbon-hydrogen and carbon-carbon bond activation are clearly rate-limiting steps for these reactions. Preferential oxidation causes depletion of bridge-bonded benzene, suggesting enhanced reactivity in this bonding configuration. When oxygen is in excess on the surface, all of the surface carbon and hydrogen is oxidized. When benzene is in excess on the surface, hydrogen produced by dehydrogenation is desorbed after all of the surface oxygen has been consumed. Repulsive interactions between benzene and molecular oxygen dominate at low temperatures. Preadsorption of oxygen inhibits adsorption of less reactive benzene in threefold hollow sites. The desorption temperature of this non-reactive chemisorbed benzene decreases and overlaps with the multilayer desorption peak with increasing oxygen exposure. The results presented here provide a clear picture of rate-limiting steps during deep oxidation of benzene on the Pt(1 1 1) surface.

Muscle oxygenation and fascicle length during passive muscle stretching in ballet-trained subjects.

PubMed

Otsuki, A; Fujita, E; Ikegawa, S; Kuno-Mizumura, M

2011-07-01

Muscle stretching transiently decreases muscle-blood flow corresponding to a muscle extension. It may disturb a balance between muscular oxygen demand and oxygen supply to muscles and reduce muscle oxygenation. However, muscle-stretching training may improve blood circulatory condition, resulting in the maintained muscle oxygenation during muscle stretching. The aim of this study was to investigate changes in muscle-blood volume (tHb) and tissue oxygenation index (TOI) during muscle stretching determined by using near-infrared spectroscopy (NIRS) in ballet-trained (BT) and untrained (C) subjects. 11 BT women who regularly perform muscle stretching and 11 C women participated in this study. Fascicle lengths, tHb and TOI in the tibialis anterior muscle were measured during passive plantar flexion from ankle joint angles of 120° (baseline) to 140°, 160°, the maximal comfortable position without pain (CP), and the maximal position (MP). At 160°, the % fascicle-length change from baseline was significantly lower in the BT than the C group, however, for the changes in tHb and TOI the significant interaction effect between the 2 groups was not detected. On the other hand, although the increases in the fascicle length from baseline to CP and MP were greater in BT than C, the tHb and TOI reductions were comparable between groups. We concluded that it appears that BT can extend their muscles without excessive reduction in muscle-blood volume and muscle oxygenation at relatively same but absolutely greater muscle-stretching levels than C. The attenuation in these indices during high-level muscle stretching may be associated with the repetitive muscle stretching of long-term ballet training. © Georg Thieme Verlag KG Stuttgart · New York.

Reactive Oxygen Species, Mitochondria, and Endothelial Cell Death during In Vitro Simulated Dives.

PubMed

Wang, Qiong; Guerrero, François; Mazur, Aleksandra; Lambrechts, Kate; Buzzacott, Peter; Belhomme, Marac; Theron, Michaël

2015-07-01

Excessive reactive oxygen species (ROS) is considered a consequence of hyperoxia and a major contributor to diving-derived vascular endothelial damage and decompression sickness. The aims of this work were: 1) to directly observe endothelial ROS production during simulated air dives as well as its relation with both mitochondrial activity and cell survival; and 2) to determine which ambient factor during air diving (hydrostatic pressure or oxygen and/or nitrogen partial pressure) is responsible for the observed modifications. In vitro diving simulation was performed with bovine arterial endothelial cells under real-time observation. The effects of air diving, hydrostatic, oxygen and nitrogen pressures, and N-acetylcysteine (NAC) treatment on mitochondrial ROS generation, mitochondrial membrane potential and cellular survival during simulation were investigated. Vascular endothelial cells performing air diving simulation suffered excessive mitochondrial ROS, mitochondrial depolarization, and cell death. These effects were prevented by NAC: after NAC treatment, the cells presented no difference in damage from nondiving cells. Oxygen diving showed a higher effect on ROS generation but lower impacts on mitochondrial depolarization and cell death than hydrostatic or nitrogen diving. Nitrogen diving had no effect on the inductions of ROS, mito-depolarization, or cell death. This study is the first direct observation of mitochondrial ROS production, mitochondrial membrane potential and cell survival during diving. Simulated air SCUBA diving induces excessive ROS production, which leads to mitochondrial depolarization and endothelial cell death. Oxygen partial pressure plays a crucial role in the production of ROS. Deleterious effects of hyperoxia-induced ROS are potentiated by hydrostatic pressure. These findings hold new implications for the pathogenesis of diving-derived endothelial dysfunction.

Influence of surface and finite size effects on the structural and magnetic properties of nanocrystalline lanthanum strontium perovskite manganites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Žvátora, Pavel; Veverka, Miroslav; Veverka, Pavel

2013-08-15

Syntheses of nanocrystalline perovskite phases of the general formula La{sub 1−x}Sr{sub x}MnO{sub 3+δ} were carried out employing sol–gel technique followed by thermal treatment at 700–900 °C under oxygen flow. The prepared samples exhibit a rhombohedral structure with space group R3{sup ¯}c in the whole investigated range of composition 0.20≤x≤0.45. The studies were aimed at the chemical composition including oxygen stoichiometry and extrinsic properties, i.e. size of the particles, both influencing the resulting structural and magnetic properties. The oxygen stoichiometry was determined by chemical analysis revealing oxygen excess in most of the studied phases. The excess was particularly high for themore » samples with the smallest crystallites (12–28 nm) while comparative bulk materials showed moderate non-stoichiometry. These differences are tentatively attributed to the surface effects in view of the volume fraction occupied by the upper layer whose atomic composition does not comply with the ideal bulk stoichiometry. - Graphical abstract: Evolution of the particle size with annealing temperature in the nanocrystalline La{sub 0.70}Sr{sub 0.30}MnO{sub 3+δ} phase. Display Omitted - Highlights: • The magnetic behaviour of nanocrystalline La{sub 1−x}Sr{sub x}MnO{sub 3+δ} phases was analyzed on the basis of their crystal structure, chemical composition and size of the particles. • Their Curie temperature and magnetization are markedly affected by finite size and surface effects. • The oxygen excess observed in the La{sub 1−x}Sr{sub x}MnO{sub 3+δ} nanoparticles might be generated by the surface layer with deviated oxygen stoichiometry.« less

RNS60, a charge-stabilized nanostructure saline alters Xenopus Laevis oocyte biophysical membrane properties by enhancing mitochondrial ATP production

PubMed Central

Choi, Soonwook; Yu, Eunah; Kim, Duk-Soo; Sugimori, Mutsuyuki; Llinás, Rodolfo R

2015-01-01

We have examined the effects of RNS60, a 0.9% saline containing charge-stabilized oxygen nanobubble-based structures. RNS60 is generated by subjecting normal saline to Taylor–Couette–Poiseuille (TCP) flow under elevated oxygen pressure. This study, implemented in Xenopus laevis oocytes, addresses both the electrophysiological membrane properties and parallel biological processes in the cytoplasm. Intracellular recordings from defolliculated X. laevis oocytes were implemented in: (1) air oxygenated standard Ringer's solution, (2) RNS60-based Ringer's solution, (3) RNS10.3 (TCP-modified saline without excess oxygen)-based Ringer's, and (4) ONS60 (saline containing high pressure oxygen without TCP modification)-based Ringer's. RNS60-based Ringer's solution induced membrane hyperpolarization from the resting membrane potential. This effect was prevented by: (1) ouabain (a blocker of the sodium/potassium ATPase), (2) rotenone (a mitochondrial electron transfer chain inhibitor preventing usable ATP synthesis), and (3) oligomycin A (an inhibitor of ATP synthase) indicating that RNS60 effects intracellular ATP levels. Increased intracellular ATP levels following RNS60 treatment were directly demonstrated using luciferin/luciferase photon emission. These results indicate that RNS60 alters intrinsic the electrophysiological properties of the X. laevis oocyte membrane by increasing mitochondrial-based ATP synthesis. Ultrastructural analysis of the oocyte cytoplasm demonstrated increased mitochondrial length in the presence of RNS60-based Ringer's solution. It is concluded that the biological properties of RNS60 relate to its ability to optimize ATP synthesis. PMID:25742953

Unearthing the secrets of mitochondrial ROS and glutathione in bioenergetics.

PubMed

Mailloux, Ryan J; McBride, Skye L; Harper, Mary-Ellen

2013-12-01

During the cellular oxidation of fuels, electrons are used to power the proton pumps of the mitochondrial electron transport chain (ETC) and ultimately drive ATP synthesis and the reduction of molecular oxygen to water. During these oxidative processes, some electrons can 'spin off' during fuel oxidation and electron transport to univalently reduce O2, forming reactive oxygen species (ROS). In excess, ROS can be detrimental; however, at low concentrations oxyradicals are essential signaling molecules. Mitochondria thus use a battery of systems to finely control types and levels of ROS, including antioxidants. Several antioxidant systems depend on glutathione. Here, we review mitochondrial ROS homeostatic systems, including emerging knowledge about roles of glutathione in redox balance and the control of protein function by post-translational modification. Copyright © 2013 Elsevier Ltd. All rights reserved.

Method of casting articles of a bulk-solidifying amorphous alloy

DOEpatents

Lin, X.; Johnson, W.L.; Peker, A.

1998-08-25

A casting charge of a bulk-solidifying amorphous alloy is cast into a mold from a temperature greater than its crystallized melting temperature, and permitted to solidify to form an article. The oxygen content of the casting charge is limited to an operable level, as excessively high oxygen contents produce premature crystallization during the casting operation. During melting, the casting charge is preferably heated to a temperature above a threshold temperature to eliminate heterogeneous crystallization nucleation sites within the casting charge. The casting charge may be cast from above the threshold temperature, or it may be cooled to the casting temperature of more than the crystallized melting point but not more than the threshold temperature, optionally held at this temperature for a period of time, and thereafter cast. 8 figs.

Quantification of fatal helium exposure following self-administration.

PubMed

Malbranque, S; Mauillon, D; Turcant, A; Rouge-Maillart, C; Mangin, P; Varlet, V

2016-11-01

Helium is nontoxic at standard conditions, plays no biological role, and is found in trace amounts in human blood. Helium can be dangerous if inhaled to excess, since it is a simple tissue hypoxia and so displaces the oxygen needed for normal respiration. This report presents a fatal case of a middle-aged male victim who died from self-administered helium exposure. For the first time, the quantification of the helium levels in gastric and lung air and in blood samples was achieved using gas chromatography-mass spectrometry after airtight sampling. The results of the toxicological investigation showed that death was caused directly by helium exposure. However, based on the pathomorphological changes detected during the forensic autopsy, we suppose that the fatal outcome was the result of the lack of oxygen after inhalation.

Method of casting articles of a bulk-solidifying amorphous alloy

DOEpatents

Lin, Xianghong; Johnson, William L.; Peker, Atakan

1998-01-01

A casting charge of a bulk-solidifying amorphous alloy is cast into a mold from a temperature greater than its crystallized melting temperature, and permitted to solidify to form an article. The oxygen content of the casting charge is limited to an operable level, as excessively high oxygen contents produce premature crystallization during the casting operation. During melting, the casting charge is preferably heated to a temperature above a threshold temperature to eliminate heterogeneous crystallization nucleation sites within the casting charge. The casting charge may be cast from above the threshold temperature, or it may be cooled to the casting temperature of more than the crystallized melting point but not more than the threshold temperature, optionally held at this temperature for a period of time, and thereafter cast.

Anemia Due to Excessive Bleeding

MedlinePlus

... the blood vessels is insufficient. The body’s oxygen supply is drastically reduced because the number of oxygen-carrying red blood cells has decreased so quickly. Either problem may lead to a heart attack , stroke , or death. Chronic blood loss Far more common than a sudden loss of ...

BENTHIC-PELAGIC PROCESSES IN PENSACOLA BAY, FL: EFFECTS OF LIGHT ON OXYGEN FLUXES

EPA Science Inventory

Eutrophication caused by excess nutrients can exacerbate hypoxia by increasing bottom water and sediment respiration. However, in shallow sub-tropical estuaries, the euphotic zone often extends below the pycnocline allowing oxygen fluxes in Pensacola Bay, FL, USA. Measurements we...

THE WATER-WATER CYCLE IN CHLOROPLASTS: Scavenging of Active Oxygens and Dissipation of Excess Photons.

PubMed

Asada, Kozi

1999-06-01

Photoreduction of dioxygen in photosystem I (PSI) of chloroplasts generates superoxide radicals as the primary product. In intact chloroplasts, the superoxide and the hydrogen peroxide produced via the disproportionation of superoxide are so rapidly scavenged at the site of their generation that the active oxygens do not inactivate the PSI complex, the stromal enzymes, or the scavenging system itself. The overall reaction for scavenging of active oxygens is the photoreduction of dioxygen to water via superoxide and hydrogen peroxide in PSI by the electrons derived from water in PSII, and the water-water cycle is proposed for these sequences. An overview is given of the molecular mechanism of the water-water cycle and microcompartmentalization of the enzymes participating in it. Whenever the water-water cycle operates properly for scavenging of active oxygens in chloroplasts, it also effectively dissipates excess excitation energy under environmental stress. The dual functions of the water-water cycle for protection from photoinihibition are discussed.

Measurement of Afterburning Effect of Underoxidized Explosives by Underwater Explosion Method

NASA Astrophysics Data System (ADS)

Cao, Wei; He, Zhongqi; Chen, Wanghua

2015-04-01

The afterburning effect of TNT and a desensitized hexogen RDX-Al explosive was studied in a defined gas volume under water. A double-layer container (DLC) filled with different gases (air, oxygen, and nitrogen) was used to control and distinguish the afterburning effect of explosives. After the charges in the DLC were initiated under water, the shock wave signals were collected and analyzed. It is shown that shock wave peak pressures are duly in compliance with explosion similarity law, pressure, and impulse histories for explosions in oxygen and air are greater than those recorded for explosions in nitrogen due to the afterburing reaction. Moreover, the afterburning energy was calculated. Results show that even though there is excess oxygen in the gas volume, the afterburning energy may not reach the theoretically maximum value. This result is different from that in confined explosion, where the presence of excess oxygen in the compressed gas filling a bomb leads to complete combustion of the detonation products.

Resuscitation with supplementary oxygen induces oxidative injury in the cerebral cortex.

PubMed

Solberg, Rønnaug; Longini, Mariangela; Proietti, Fabrizio; Vezzosi, Piero; Saugstad, Ola Didrik; Buonocore, Giuseppe

2012-09-01

Isoprostanes, neuroprostanes, isofurans, and neurofurans have all become attractive biomarkers of oxidative damage and lipid peroxidation in brain tissue. Asphyxia and subsequent reoxygenation cause a burst of oxygen free radicals. Isoprostanes and isofurans are generated by free radical attacks of esterified arachidonic acid. Neuroprostanes and neurofurans are derived from the peroxidation of docosahexanoic acid, which is abundant in neurons and could therefore more selectively represent oxidative brain injury. Newborn piglets (age 12-36 h) underwent hypoxia until the base excess reached -20 mmol/L or the mean arterial blood pressure dropped below 15 mm Hg. They were randomly assigned to receive resuscitation with 21, 40, or 100% oxygen for 30 min and then ventilation with air. The levels of isoprostanes, isofurans, neuroprostanes, and neurofurans were determined in brain tissue (ng/g) isolated from the prefrontal cortex using gas chromatography-mass spectrometry (GC/MS) with negative ion chemical ionization (NICI) techniques. A control group underwent the same procedures and observations but was not submitted to hypoxia or hyperoxia. Hypoxia and reoxygenation significantly increased the levels of isoprostanes, isofurans, neuroprostanes, and neurofurans in the cerebral cortex. Nine hours after resuscitation with 100% oxygen for 30 min, there was nearly a 4-fold increase in the levels of isoprostanes and isofurans compared to the control group (P=0.007 and P=0.001) and more than a 2-fold increase in neuroprostane levels (P=0.002). The levels of neuroprostanes and neurofurans were significantly higher in the piglets that were resuscitated with supplementary oxygen (40 and 100%) compared to the group treated with air (21%). The significance levels of the observed differences in neuroprostanes for the 21% vs 40% comparison and the 21% vs 100% comparison were P<0.001 and P=0.001, respectively. For neurofurans, the P values of the 21% vs 40% comparison and the 21% vs 100% comparison were P=0.036 and P=0.025, respectively. Supplementary oxygen used for the resuscitation of newborns increases lipid peroxidation in brain cortical neurons, a result that is indicative of oxidative brain damage. These novel findings provide new knowledge regarding the relationships between oxidative brain injury and resuscitation with oxygen. Copyright © 2012 Elsevier Inc. All rights reserved.

Dietary antioxidants for the athlete.

PubMed

Atalay, Mustafa; Lappalainen, Jani; Sen, Chandan K

2006-06-01

Physical exercise induces oxidative stress and tissue damage. Although a basal level of reactive oxygen species (ROS) is required to drive redox signaling and numerous physiologic processes, excess ROS during exercise may have adverse implications on health and performance. Antioxidant nutrients may be helpful in that regard. Caution should be exercised against excess antioxidant supplements, however. This article presents a digest for sports practitioners. The following three recommendations are made: 1) it is important to determine the individual antioxidant need of each athlete performing a specific sport; 2) multinutrient preparations, as opposed to megadoses of any single form of nutrient, seem to be a more prudent path to choose; and 3) for outcomes of antioxidant supplementation, performance should not be the only criteria. Overall well being of the athlete, faster recovery, and minimization of injury time could all be affected by antioxidant therapy.

Development for application of parylene coatings. [to hybrid microcircuits devices

NASA Technical Reports Server (NTRS)

Oberin, F. W.

1974-01-01

A practical method of applying a parylene (paraxylene) coating to hybrid microcircuit devices was developed for the prevention of circuit malfunctions existing prior to package sealing or formed upon exposure to the service environment. It was found that paralene and an associated primer (if used) had generally little or no adverse effect on the active and passive elements of typical hybrid microcircuits. Exceptions were related to high frequency circuitry, low resistivity thick film resistors, and highly sensitive PIN diodes. Advantages of the use of the coating included increased dielectric strength and increased interconnection bond strength. Coating service life in nitrogen or nitrogen with low levels of oxygen as a contaminant is shown to be in excess of 1000 hours at 150 C and can be projected to be in excess of 5000 hours at 125 C.

Synthetic nickel-containing superoxide dismutase attenuates para-phenylenediamine-induced bladder dysfunction in rats

PubMed Central

Chiang, Bing-Juin; Chen, Tien-Wen; Chung, Shiu-Dong; Lee, Way-Zen; Chien, Chiang-Ting

2017-01-01

Para (p)-phenylenediamine and its toxic metabolites induce excess reactive oxygen species formation that results in bladder voiding dysfunction. We determined the effects of synthetic Ni-containing superoxide dismutase mimics and the role of oxidative stress in p-phenylenediamine-induced urinary bladder dysfunction. P-phenylenediamine (60 μg/kg/day) was intraperitoneally administered for 4 weeks to induce bladder injury in female Wistar rats. Synthetic Ni-containing superoxide dismutase mimics, WCT003 (1.5 mg/kg) and WCT006 (1.5 mg/kg), were then intraperitoneally administered for 2 weeks. Transcystometrograms were performed in urethane-anesthetized rats. The in vitro and in vivo reactive oxygen species levels and pathological changes in formalin-fixed bladder sections were evaluated. Western blotting and immunohistochemistry elucidated the pathophysiological mechanisms of oxidative stress-induced apoptosis, autophagy, and pyroptosis. P-phenylenediamine increased voiding frequency, blood and urinary bladder levels of reactive oxygen species, and neutrophil and mast cell infiltration. It also upregulated biomarkers of autophagy (LC3 II), apoptosis (poly (ADP-ribose) polymerase), and pyroptosis (Caspase 1). WCT003 and WCT006 ameliorated reactive oxygen species production, inflammation, apoptosis, autophagy, pyroptosis, and bladder hyperactivity. P-phenylenediamine increased oxidative stress, inflammatory leukocytosis, autophagy, apoptosis, and pyroptosis formation within the urinary bladder. Novel synthetic nickel-containing superoxide dismutase mimics relieved p-phenylenediamine-induced bladder inflammation and voiding dysfunction. PMID:29285288

The defect chemistry of UO2 ± x from atomistic simulations

NASA Astrophysics Data System (ADS)

Cooper, M. W. D.; Murphy, S. T.; Andersson, D. A.

2018-06-01

Control of the defect chemistry in UO2 ± x is important for manipulating nuclear fuel properties and fuel performance. For example, the uranium vacancy concentration is critical for fission gas release and sintering, while all oxygen and uranium defects are known to strongly influence thermal conductivity. Here the point defect concentrations in thermal equilibrium are predicted using defect energies from density functional theory (DFT) and vibrational entropies calculated using empirical potentials. Electrons and holes have been treated in a similar fashion to other charged defects allowing for structural relaxation around the localized electronic defects. Predictions are made for the defect concentrations and non-stoichiometry of UO2 ± x as a function of oxygen partial pressure and temperature. If vibrational entropy is omitted, oxygen interstitials are predicted to be the dominant mechanism of excess oxygen accommodation over only a small temperature range (1265 K-1350 K), in contrast to experimental observation. Conversely, if vibrational entropy is included oxygen interstitials dominate from 1165 K to 1680 K (Busker potential) or from 1275 K to 1630 K (CRG potential). Below these temperature ranges, excess oxygen is predicted to be accommodated by uranium vacancies, while above them the system is hypo-stoichiometric with oxygen deficiency accommodated by oxygen vacancies. Our results are discussed in the context of oxygen clustering, formation of U4O9, and issues for fuel behavior. In particular, the variation of the uranium vacancy concentrations as a function of temperature and oxygen partial pressure will underpin future studies into fission gas diffusivity and broaden the understanding of UO2 ± x sintering.

O-16 excesses in Murchison and Murray hibonites - A case against a late supernova injection origin of isotopic anomalies in O, Mg, Ca, and Ti

NASA Technical Reports Server (NTRS)

Fahey, A. J.; Goswami, J. N.; Mckeegan, K. D.; Zinner, E. K.

1987-01-01

Ion probe measurements of the oxygen isotopic composition of seven hibonite samples from the CM chondrites Murchison and Murray are reported. All samples show large O-16 excesses relative to terrestrial oxygen. The data for all samples plot along the carbonaceous chondrite O-16-rich mixing line and show no evidence for isotopic mass fractionation effects characteristic of FUN inclusions. These hibonites have the largest Ca-48 and Ti-50 isotopic anomalies found to date; thus there is no intrinsic relationship between anomalies of a nucleosynthetic origin and isotopic mass fractionation effects. The large O-16 excess seen in the sample with the largest measured Ca-48 and Ti-50 depletions argues against a late injection of exotic material from a nearby supernova as a source for the isotopic anomalies.

Rhenium-Foil Witness Cylinders

NASA Technical Reports Server (NTRS)

Knight, B. L.

1992-01-01

Cylindrical portion of wall of combustion chamber replaced with rhenium foil mounted on holder. Rhenium oxidizes without melting, indicating regions of excess oxidizer in combustion-chamber flow. Rhenium witness foils also useful in detecting excess oxygen and other oxidizers at temperatures between 2,000 and 3,600 degrees F in burner cores of advanced gas-turbine engines.

Impact of stormwater infiltration basins on groundwater quality, Perth metropolitan region, Western Australia

NASA Astrophysics Data System (ADS)

Appleyard, S. J.

1993-08-01

Twelve bores were sunk adjacent to three stormwater infiltration basins in the Perth metropolitan area to examine the impact of runoff from a light industrial area, a medium-density residential area, and a major arterial road on groundwater quality, and to examine the hydrological response of the aquifer to runoff recharge. Automatic and manual water level monitoring between April and November 1990 indicated that groundwater levels responded within minutes to recharge from the infiltration basins. Peak water levels of up to 2.5 m above rest levels occurred 6 24 h after the commencement of ponding in the infiltration basins. There was a marked reduction in salinity and increase in dissolved oxygen concentrations in the upper part of the aquifer downgradient of the infiltration basins. Concentrations of toxic metals, nutrients, pesticides, and phenolic compounds in groundwater near the infiltration basins were low and generally well within Australian drinking water guidelines. However, sediment in the base of an infiltration basin draining a major road contained in excess of 3500 ppm of lead. Phthalates, which are US EPA priority pollutants, were detected in all but one bore near the infiltration basins. Their detection may be a sampling artifact, but they may also be derived from the plastic litter that accumulates in the infiltration basins. The concentration of iron in groundwater near the infiltration basins appears to be controlled by dissolved oxygen concentrations, with high iron concentrations occurring where dissolved oxygen concentrations are low. Pumping bores located near infiltration basins may suffer from iron encrustation problems caused by the mixing of shallow, oxygenated groundwater with water containing higher concentrations of iron from deeper in the aquifer.

Prevalence, clinical profile, iron status, and subject-specific traits for excessive erythrocytosis in andean adults living permanently at 3,825 meters above sea level.

PubMed

De Ferrari, Aldo; Miranda, J Jaime; Gilman, Robert H; Dávila-Román, Victor G; León-Velarde, Fabiola; Rivera-Ch, Maria; Huicho, Luis; Bernabé-Ortiz, Antonio; Wise, Robert A; Checkley, William

2014-11-01

Excessive erythrocytosis (EE) is a prevalent condition in populations living at high altitudes (> 2,500 m above sea level). Few large population-based studies have explored the association between EE and multiple subject-specific traits including oxygen saturation, iron status indicators, and pulmonary function. We enrolled a sex-stratified and age-stratified sample of 1,065 high-altitude residents aged ≥ 35 years from Puno, Peru (3,825 m above sea level) and conducted a standardized questionnaire and physical examination that included spirometry, pulse oximetry, and a blood sample for multiple clinical markers. Our primary objectives were to estimate the prevalence of EE, characterize the clinical profile and iron status indicators of subjects with EE, and describe subject-specific traits associated with EE. Overall prevalence of EE was 4.5% (95% CI, 3.3%-6.0%). Oxygen saturation was significantly lower among EE than non-EE group subjects (85.3% vs 90.1%, P < .001) but no difference was found in iron status indicators between both groups (P > .09 for all values). In multivariable logistic regression, we found that age ≥ 65 years (OR = 2.45, 95% CI, 1.16-5.09), male sex (3.86, 1.78-9.08), having metabolic syndrome (2.66, 1.27-5.75) or being overweight (5.20, 1.95-16.77), pulse oximetry < 85% (14.90, 6.43-34.90), and % predicted FVC < 80% (13.62, 4.40-41.80) were strongly associated with EE. Attributable fractions for EE were greatest for being overweight (26.7%), followed by male sex (21.5%), pulse oximetry < 85% (16.4%), having metabolic syndrome (14.4%), and % predicted FVC < 80% (9.3%). We found a lower prevalence of EE than in previous reports in the Peruvian Andes. Although the presence of hypoxemia and decreased vital capacity were strongly associated with excessive erythrocytosis, being overweight or having metabolic syndrome were associated with an important fraction of cases in our study population.

Prevalence, Clinical Profile, Iron Status, and Subject-Specific Traits for Excessive Erythrocytosis in Andean Adults Living Permanently at 3,825 Meters Above Sea Level

PubMed Central

De Ferrari, Aldo; Miranda, J. Jaime; Gilman, Robert H.; Dávila-Román, Victor G.; León-Velarde, Fabiola; Rivera-Ch, Maria; Huicho, Luis; Bernabé-Ortiz, Antonio; Wise, Robert A.

2014-01-01

BACKGROUND: Excessive erythrocytosis (EE) is a prevalent condition in populations living at high altitudes (> 2,500 m above sea level). Few large population-based studies have explored the association between EE and multiple subject-specific traits including oxygen saturation, iron status indicators, and pulmonary function. METHODS: We enrolled a sex-stratified and age-stratified sample of 1,065 high-altitude residents aged ≥ 35 years from Puno, Peru (3,825 m above sea level) and conducted a standardized questionnaire and physical examination that included spirometry, pulse oximetry, and a blood sample for multiple clinical markers. Our primary objectives were to estimate the prevalence of EE, characterize the clinical profile and iron status indicators of subjects with EE, and describe subject-specific traits associated with EE. RESULTS: Overall prevalence of EE was 4.5% (95% CI, 3.3%-6.0%). Oxygen saturation was significantly lower among EE than non-EE group subjects (85.3% vs 90.1%, P < .001) but no difference was found in iron status indicators between both groups (P > .09 for all values). In multivariable logistic regression, we found that age ≥ 65 years (OR = 2.45, 95% CI, 1.16-5.09), male sex (3.86, 1.78-9.08), having metabolic syndrome (2.66, 1.27-5.75) or being overweight (5.20, 1.95-16.77), pulse oximetry < 85% (14.90, 6.43-34.90), and % predicted FVC < 80% (13.62, 4.40-41.80) were strongly associated with EE. Attributable fractions for EE were greatest for being overweight (26.7%), followed by male sex (21.5%), pulse oximetry < 85% (16.4%), having metabolic syndrome (14.4%), and % predicted FVC < 80% (9.3%). CONCLUSIONS: We found a lower prevalence of EE than in previous reports in the Peruvian Andes. Although the presence of hypoxemia and decreased vital capacity were strongly associated with excessive erythrocytosis, being overweight or having metabolic syndrome were associated with an important fraction of cases in our study population. PMID:24874587

Electrochemical control of iodine disinfectant for space transportation system and space station potable water

NASA Technical Reports Server (NTRS)

Geer, Richard D.

1989-01-01

An electrochemical microbial check valve method (EC-MCV) for controlling the iodine disinfectant in potable water (PW) for NASA's space operations was proposed. The factors affecting the design and performance of the unit were analyzed. This showed that it would be feasible to construct a recyclable unit in a small volume that will operate in either an iodine removal or addition mode. The EC-MCV should remove active iodine species rapidly from PW, but the rapid delivery rates at end-use may make complete removal of excess I(-) difficult under some conditions. Its performace change with AgI buildup needs to be investigated, as this controls the time for recycling the unit. The EC-MCV has advantages over the passive microbial check valve (MCV) method currently in use, as it would allow precise control of the I2 level and would not introduce excess I(-) to the water. The presence of oxygen in the EC-MCV needs to be investigated as it could affect the efficiency of I2 addition and excess I(-) removal.

Docosahexaenoic acid prevents paraquat-induced reactive oxygen species production in dopaminergic neurons via enhancement of glutathione homeostasis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Hyoung Jun; Han, Jeongsu; Jang, Yunseon

Highlights: • DHA prevents PQ-induced dopaminergic neuronal loss via decreasing of excessive ROS. • DHA increases GR and GCLm derivate GSH pool by enhancement of Nrf2 expression. • Protective mechanism is removal of PQ-induced ROS via DHA-dependent GSH pool. • DHA may be a good preventive strategy for Parkinson’s disease (PD) therapy. - Abstract: Omega-3 polyunsaturated fatty acid levels are reduced in the substantia nigra area in Parkinson’s disease patients and animal models, implicating docosahexaenoic acid (DHA) as a potential treatment for preventing Parkinson’s disease and suggesting the need for investigations into how DHA might protect against neurotoxin-induced dopaminergic neuronmore » loss. The herbicide paraquat (PQ) induces dopaminergic neuron loss through the excessive production of reactive oxygen species (ROS). We found that treatment of dopaminergic SN4741 cells with PQ reduced cell viability in a dose-dependent manner, but pretreatment with DHA ameliorated the toxic effect of PQ. To determine the toxic mechanism of PQ, we measured intracellular ROS content in different organelles with specific dyes. As expected, all types of ROS were increased by PQ treatment, but DHA pretreatment selectively decreased cytosolic hydrogen peroxide content. Furthermore, DHA treatment-induced increases in glutathione reductase and glutamate cysteine ligase modifier subunit (GCLm) mRNA expression were positively correlated with glutathione (GSH) content. Consistent with this increase in GCLm mRNA levels, Western blot analysis revealed that DHA pretreatment increased nuclear factor-erythroid 2 related factor 2 (Nrf2) protein levels. These findings indicate that DHA prevents PQ-induced neuronal cell loss by enhancing Nrf2-regulated GSH homeostasis.« less

Linear air-fuel sensor development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garzon, F.; Miller, C.

1996-12-14

The electrochemical zirconia solid electrolyte oxygen sensor, is extensively used for monitoring oxygen concentrations in various fields. They are currently utilized in automobiles to monitor the exhaust gas composition and control the air-to-fuel ratio, thus reducing harmful emission components and improving fuel economy. Zirconia oxygen sensors, are divided into two classes of devices: (1) potentiometric or logarithmic air/fuel sensors; and (2) amperometric or linear air/fuel sensors. The potentiometric sensors are ideally suited to monitor the air-to-fuel ratio close to the complete combustion stoichiometry; a value of about 14.8 to 1 parts by volume. This occurs because the oxygen concentration changesmore » by many orders of magnitude as the air/fuel ratio is varied through the stoichiometric value. However, the potentiometric sensor is not very sensitive to changes in oxygen partial pressure away from the stoichiometric point due to the logarithmic dependence of the output voltage signal on the oxygen partial pressure. It is often advantageous to operate gasoline power piston engines with excess combustion air; this improves fuel economy and reduces hydrocarbon emissions. To maintain stable combustion away from stoichiometry, and enable engines to operate in the excess oxygen (lean burn) region several limiting-current amperometric sensors have been reported. These sensors are based on the electrochemical oxygen ion pumping of a zirconia electrolyte. They typically show reproducible limiting current plateaus with an applied voltage caused by the gas diffusion overpotential at the cathode.« less

Dietary low or excess levels of lipids reduced growth performance, and impaired immune function and structure of head kidney, spleen and skin in young grass carp (Ctenopharyngodon idella) under the infection of Aeromonas hydrophila.

PubMed

Ni, Pei-Jun; Jiang, Wei-Dan; Wu, Pei; Liu, Yang; Kuang, Sheng-Yao; Tang, Ling; Tang, Wu-Neng; Zhang, Yong-An; Zhou, Xiao-Qiu; Feng, Lin

2016-08-01

Our study explored the effect of dietary lipids on growth and immunity and structure (head kidney, spleen and skin) of young grass carp (Ctenopharyngodon idella). A total of 540 young grass carp with an average initial weight of 261.41 ± 0.53 g were fed diets containing six graded levels of lipids at 5.9-80.1 g/kg diet for 8 weeks. After that, a challenge trial was conducted by injection of Aeromonas hydrophila over 2 weeks. The results indicated that compared with optimal lipids supplementation, low and excess levels of lipids down-regulated the mRNA levels of antimicrobial peptides, anti-inflammatory cytokines, inhibitor of κBα (IκBα) and ribosomal p70S6 kinase (S6K1), and up-regulated pro-inflammatory cytokines, nuclear factor κB p65 (NF-κB p65), NF-κB c-Rel (not p52), IκB kinase α (IKKα), IKKβ, IKKγ, and eIF4E-binding protein (4EBP) mRNA levels in the head kidney and spleen of young grass carp (P < 0.05). Low or excess levels of lipids also increased reactive oxygen species (ROS) production and malondialdehyde (MDA) and protein carbonyl (PC) contents, reduced the activities of antioxidant enzymes (P < 0.05), down-regulate the relative mRNA levels of antioxidant enzymes and NF-E2-related factor 2 (Nrf2), and up-regulated the expression levels of Kelch-like ECH-associating protein 1a (Keap1a) and Keap1b in the head kidney and spleen. In addition, low or excess levels of lipids down-regulated the mRNA levels of B-cell lymphoma-2 (Bcl-2) and inhibitor of apoptosis protein (IAP) in the head kidney and spleen, whereas up-regulated the mRNA levels of apoptotic protease activating factor-1 (Apaf-1), caspase 3, 7, 8 and 9 mRNA levels in the head kidney and spleen and Fas ligand (FasL) mRNA levels in the spleen of young grass carp, suggesting that low or excess levels of lipids could decrease the head kidney and spleen immune function, induce oxidative damage and apoptosis and impair antioxidant system of young grass carp. At last, low or excess levels of lipids also impaired the immune function and structure in the skin of young grass carp. Based on the quadratic regression analysis for PWG, skin haemorrhage and lesions morbidity and IgM content, the dietary lipids requirements for young grass carp were estimated to be 43.7, 60.2, 55.0 and 52.1 g/kg diet, respectively. Copyright © 2016. Published by Elsevier Ltd.

The role of Hibiscus sabdariffa L. (Roselle) in maintenance of ex vivo murine bone marrow-derived hematopoietic stem cells.

PubMed

Abdul Hamid, Zariyantey; Lin Lin, Winnie Hii; Abdalla, Basma Jibril; Bee Yuen, Ong; Latif, Elda Surhaida; Mohamed, Jamaludin; Rajab, Nor Fadilah; Paik Wah, Chow; Wak Harto, Muhd Khairul Akmal; Budin, Siti Balkis

2014-01-01

Hematopoietic stem cells- (HSCs-) based therapy requires ex vivo expansion of HSCs prior to therapeutic use. However, ex vivo culture was reported to promote excessive production of reactive oxygen species (ROS), exposing HSCs to oxidative damage. Efforts to overcome this limitation include the use of antioxidants. In this study, the role of Hibiscus sabdariffa L. (Roselle) in maintenance of cultured murine bone marrow-derived HSCs was investigated. Aqueous extract of Roselle was added at varying concentrations (0-1000 ng/mL) for 24 hours to the freshly isolated murine bone marrow cells (BMCs) cultures. Effects of Roselle on cell viability, reactive oxygen species (ROS) production, glutathione (GSH) level, superoxide dismutase (SOD) activity, and DNA damage were investigated. Roselle enhanced the survival (P < 0.05) of BMCs at 500 and 1000 ng/mL, increased survival of Sca-1(+) cells (HSCs) at 500 ng/mL, and maintained HSCs phenotype as shown from nonremarkable changes of surface marker antigen (Sca-1) expression in all experimental groups. Roselle increased (P < 0.05) the GSH level and SOD activity but the level of reactive oxygen species (ROS) was unaffected. Moreover, Roselle showed significant cellular genoprotective potency against H2O2-induced DNA damage. Conclusively, Roselle shows novel property as potential supplement and genoprotectant against oxidative damage to cultured HSCs.

The Role of Hibiscus sabdariffa L. (Roselle) in Maintenance of Ex Vivo Murine Bone Marrow-Derived Hematopoietic Stem Cells

PubMed Central

Abdul Hamid, Zariyantey; Lin Lin, Winnie Hii; Abdalla, Basma Jibril; Bee Yuen, Ong; Latif, Elda Surhaida; Mohamed, Jamaludin; Rajab, Nor Fadilah; Paik Wah, Chow; Budin, Siti Balkis

2014-01-01

Hematopoietic stem cells- (HSCs-) based therapy requires ex vivo expansion of HSCs prior to therapeutic use. However, ex vivo culture was reported to promote excessive production of reactive oxygen species (ROS), exposing HSCs to oxidative damage. Efforts to overcome this limitation include the use of antioxidants. In this study, the role of Hibiscus sabdariffa L. (Roselle) in maintenance of cultured murine bone marrow-derived HSCs was investigated. Aqueous extract of Roselle was added at varying concentrations (0–1000 ng/mL) for 24 hours to the freshly isolated murine bone marrow cells (BMCs) cultures. Effects of Roselle on cell viability, reactive oxygen species (ROS) production, glutathione (GSH) level, superoxide dismutase (SOD) activity, and DNA damage were investigated. Roselle enhanced the survival (P < 0.05) of BMCs at 500 and 1000 ng/mL, increased survival of Sca-1+ cells (HSCs) at 500 ng/mL, and maintained HSCs phenotype as shown from nonremarkable changes of surface marker antigen (Sca-1) expression in all experimental groups. Roselle increased (P < 0.05) the GSH level and SOD activity but the level of reactive oxygen species (ROS) was unaffected. Moreover, Roselle showed significant cellular genoprotective potency against H2O2-induced DNA damage. Conclusively, Roselle shows novel property as potential supplement and genoprotectant against oxidative damage to cultured HSCs. PMID:25405216

Oxygen-storage behavior and local structure in Ti-substituted YMnO{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Levin, I., E-mail: igor.levin@nist.gov; Krayzman, V.; Vanderah, T.A.

Hexagonal manganates RMnO{sub 3} (R=Y, Ho, Dy) have been recently shown to exhibit oxygen-storage capacities promising for three-way catalysts, air-separation, and related technologies. Here, we demonstrate that Ti substitution for Mn can be used to chemically tune the oxygen-breathing properties of these materials towards practical applications. Specifically, Y(Mn{sub 1−x}Ti{sub x})O{sub 3} solid solutions exhibit facile oxygen absorption/desorption via reversible Ti{sup 3+}↔Ti{sup 4+} and Mn{sup 3+}↔Mn{sup 4+} reactions already in ambient air at ≈400 °C and ≈250 °C, respectively. On cooling, the oxidation of both cations is accompanied by oxygen uptake yielding a formula YMn{sup 3+}{sub 1−x-y}Mn{sup 4+}{sub y}Ti{sup 4+}{sub x}O{submore » 3+δ}. The presence of Ti promotes the oxidation of Mn{sup 3+} to Mn{sup 4+}, which is almost negligible for YMnO{sub 3} in air, thereby increasing the uptake of oxygen beyond that required for a given Ti{sup 4+} concentration. The reversibility of the redox reactions is limited by sluggish kinetics; however, the oxidation process continues, if slowly, even at room temperature. The extra oxygen atoms are accommodated by the large interstices within a triangular lattice formed by the [MnO{sub 5}] trigonal bipyramids. According to bond distances from Rietveld refinements using the neutron diffraction data, the YMnO{sub 3} structure features under-bonded Mn and even more severely under-bonded oxygen atoms that form the trigonal bases of the [MnO{sub 5}] bipyramids. The tensile bond strain around the 5-fold coordinated Mn site and the strong preference of Ti{sup 4+}(and Mn{sup 4+}) for higher coordination numbers likely provide driving forces for the oxidation reaction. Reverse Monte Carlo refinements of the local atomic displacements using neutron total scattering revealed how the excess oxygen atoms are accommodated in the structure by correlated local displacements of the host atoms. Large displacements of the under-bonded host oxygen atoms play a key part in this lattice-relaxation process, facilitating reversible exchange of significant amounts of oxygen with atmosphere. - Graphical abstract: Concurrent redox reactions involving Ti and Mn yield facile absorption/desorption of excess oxygen. - Highlights: • Concurrent redox reactions involving Ti and Mn yield oxygen absorption/desorption. • Excess oxygen is accommodated as interstitials via correlated atomic shifts. • Oxygen breathing is facilitated by the under-bonding of host Mn and O atoms.« less

Surface acoustic wave oxygen sensor

NASA Technical Reports Server (NTRS)

Collman, James P.; Oglesby, Donald M.; Upchurch, Billy T.; Leighty, Bradley D.; Zhang, Xumu; Herrmann, Paul C.

1994-01-01

A surface acoustic wave (SAW) device that responds to oxygen pressure was developed by coating a 158 MHz quartz surface acoustic wave (SAW) device with an oxygen binding agent. Two types of coatings were used. One type was prepared by dissolving an oxygen binding agent in a toluene solution of a copolymer containing the axial ligand. A second type was prepared with an oxygen binding porphyrin solution containing excess axial ligand without a polymer matrix. In the polymer based coatings, the copolymer served to provide the axial ligand to the oxygen binding agent and as a coating matrix on the surface of the SAW device. The oxygen sensing SAW device has been shown to bind oxygen following a Langmuir isotherm and may be used to measure the equilibrium constant of the oxygen binding compound in the coating matrix.

Phosphate adsorption on aluminum-impregnated mesoporous silicates : surface structure and behavior of adsorbents

Treesearch

Eun Woo Shin; James S. Han; Min Jang; Soo-Hong Min; Jae Kwang Park; Roger M. Rowell

2004-01-01

Phosphorus from excess fertilizers and detergents ends up washing into lakes, creeks, and rivers. This overabundance of phosphorus causes excessive aquatic plant and algae growth and depletes the dissolved oxygen supply in the water. In this study, aluminum-impregnated mesoporous adsorbents were tested for their ability to remove phosphate from water. The surface...

40 CFR 63.1205 - What are the standards for hazardous waste burning lightweight aggregate kilns that are effective...

Code of Federal Regulations, 2013 CFR

2013-07-01

... as propane; (6) Hydrochloric acid and chlorine gas in excess of 600 parts per million by volume, combined emissions, expressed as hydrochloric acid equivalents, dry basis and corrected to 7 percent oxygen...) Hydrochloric acid and chlorine gas in excess of 600 parts per million by volume, combined emissions, expressed...

40 CFR 63.1205 - What are the standards for hazardous waste burning lightweight aggregate kilns that are effective...

Code of Federal Regulations, 2014 CFR

2014-07-01

... as propane; (6) Hydrochloric acid and chlorine gas in excess of 600 parts per million by volume, combined emissions, expressed as hydrochloric acid equivalents, dry basis and corrected to 7 percent oxygen...) Hydrochloric acid and chlorine gas in excess of 600 parts per million by volume, combined emissions, expressed...

Determination of 17O-excess of terrestrial silicate/oxide minerals with respect to Vienna Standard Mean Ocean Water (VSMOW).

PubMed

Tanaka, Ryoji; Nakamura, Eizo

2013-01-30

Oxygen triple isotope compositions give key information for understanding physical processes during isotopic fractionation between the geo-, hydro-, bio-, and atmosphere. For detailed discussion of these topics, it is necessary to determine precise (17)O-excess values of terrestrial silicate/oxide minerals with respect to Vienna Standard Mean Ocean Water (VSMOW). Water was fluorinated in an electrically heated Ni-metal tube into which water and BrF(5) were loaded for the quantitative extraction of oxygen. Silicate/oxide minerals were fluorinated by heating with a CO(2) laser in an atmosphere of BrF(5). The extracted oxygen was purified and isotope ratios of the oxygen triple isotope compositions were determined using a Finnigan MAT253 isotope ratio mass spectrometer. The oxygen triple isotope compositions of meteoric water and terrestrial silicate/oxide minerals fall on statistically distinguishable fractionation lines, defined as [ln(δ(17)O + 1) = λln(δ(18) O + 1) + Δ], where λ and Δ correspond to the slope and intercept, respectively. The fractionation line for meteoric water has λ = 0.5285 ± 0.0005 and Δ = 0.03 ± 0.02‰ and for terrestrial silicate/oxide minerals has λ = 0.5270 ± 0.0005 and Δ = -0.070 ± 0.005‰, at the 95% confidence limit. All the analyzed terrestrial silicate/oxide minerals including internationally accepted reference materials (NBS-28, UWG-2, and San Carlos olivine) have a negative (17)O-excess with respect to VSMOW. We propose that it is necessary to specify if the determined δ(17)O values of terrestrial and extraterrestrial samples are expressed as the difference from VSMOW or the terrestrial silicate mineral-corrected value. Copyright © 2012 John Wiley & Sons, Ltd.

Status of and changes in water quality monitored for the Idaho statewide surface-water-quality network, 1989—2002

USGS Publications Warehouse

Hardy, Mark A.; Parliman, Deborah J.; O'Dell, Ivalou

2005-01-01

Idaho has. Although erodable soils are likely a cause of elevated turbidities, suspended-sediment concentrations were not strongly correlated with turbidities. Dissolved-solids and hardness concentrations were strongly correlated. This is probably because the limestones present in some basins are more soluble than the igneous rocks that predominate in others. Low hardness in streams of northern Idaho, where watersheds are underlain by resistant igneous rocks, enhances the toxicity of some trace elements to aquatic life in these streams. Only a few measurements of dissolved-oxygen concentrations at six sites were less than 6.0 milligrams per liter, the Idaho minimum criterion for protection of aquatic organisms. High supersaturations of dissolved oxygen at four sites suggest excessive photosynthetic activity by algal communities. Nighttime monitoring would help determine whether dissolved-oxygen concentrations at these sites might fall below the Idaho criterion. Data from four sites suggest that dissolved-oxygen concentrations may have decreased over time. The pH at 15 sites sometimes fell outside the range specified (6.5-9.0) for the protection of aquatic organisms in Idaho streams. Values exceeded 9.0 at 10 sites, probably because of excessive algal photosynthetic activity in waters where carbonate rocks are present. Values were sometimes less than 6.5 at five sites in areas of mountain bedrock geology where pH is likely to be naturally low. Mining activities also may contribute to low pH at some of these sites. Inorganic nitrogen and total phosphorus concentrations commonly exceeded those considered sufficient for supporting excess algal production (0.3 and 0.1 milligrams per liter, respectively). Data from a few sites suggest that nitrogen and(or) phosphorus concentrations might be changing over time. Low concentrations of nitrogen and phosphorus at six sites, most representing forested basins, might make them good candidates as reference sites that represent naturally occurring nutrient concentrations. Trace elements examined for this report were cadmium, copper, lead, mercury, selenium, and zinc. In water, many trace-element concentrations were below the minimum analytical reporting levels. Concentrations of cadmium, copper, lead, and zinc generally were highest in mined and other mineral-rich basins in northern Idaho. Concentrations of mercury were

77 FR 34149 - Heavy-Duty Highway Program: Revisions for Emergency Vehicles and SCR Maintenance

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-08

... soot. Since this burning can involve extra heat and/or oxygen or oxygen- containing compounds, this... fuel consumption. This loss in performance may be noticed by the vehicle operator in terms of poor... excessive amounts of trapped PM begin to oxidize at high temperatures (i.e., DPF regeneration temperatures...

Extending the application of deuterium excess as a tracer in surface and groundwaters

NASA Astrophysics Data System (ADS)

Hurst, S.; Krishnamurthy, R. V.

2017-12-01

Stable isotopes of surface and ground waters provide invaluable information on the processes involved in their genesis. A starting point in these applications is the relationship between hydrogen (δ2H) and oxygen (δ18O), exemplified in the so-called Global Meteoric Water Line where δ2H=8δ18O+10 [1]. From this line Dansgaard [2] defined the parameter deuterium excess where d=δ2H-8δ18O. Generally, the d-excess value is fixed at the source, predominantly the equatorial oceans and retained. At an average humidity of about 85% the expected d-excess value is 10. Deviations indicate secondary changes in the air mass or a water body thus making d-excess a useful geophysical tracer. For instance, evaporation results in a higher d-excess in the vapor. Mixing of this water vapor with overhead air mass results in precipitation exhibiting d-excess values higher than Global Meteoric Water Line [3]. Alternatively, the fraction of liquid remaining will have low d-excess and in extreme cases negative d-excess. In this case a plot of d-excess-δ2H will give a straight line with a negative slope. This can be demonstrated from pan evaporation experiments [4]. Deviation from a perfect straight line on the d-excess-δ2H plot indicates a combination of mixing from various source waters and evaporation. This study will discuss various case studies from multiple environments applying this approach using d-excess. References [1] Craig, H. Standard for Reporting Concentrations of Deuterium and Oxygen-18 in Natural Waters. Science 133, 1833-1834 (1961). [2] Dansgaard, W. Stable isotopes in precipitation. Tellus A 16: 436-468 (1964). [3] Machavaram, M. &, Krishnamurthy, R.V. Earth surface evaporative process: a case study from the Great Lakes region of the United States based on deuterium excess in precipitation. Geochim. et Cosmochem. Acta 59, 4279-4283 (1995). [4] Simpson, H.J., Hamza, M.S., & White, J.W.C. Evaporative enrichment of deuterium and 18O in arid zone irrigation. IAEA, 241-256 (1987).

Single crystal X-ray diffraction study of the HgBa2CuO4+δ superconducting compound

NASA Astrophysics Data System (ADS)

Bordet, P.; Duc, F.; Lefloch, S.; Capponi, J. J.; Alexandre, E.; Rosa-Nunes, M.; Antipov, E. V.; Putilin, S.

1996-02-01

A high precision X-ray diffraction analysis up to sin θ/λ = 1.15 of a HgBa2CuO4+δ single crystal having a Tc of ~ 90 K is presented. The cell parameters are a = 3.8815(4), c = 9.485 (7) Å. The refinements indicate the existence of a split barium site due to the presence of excess oxygen in the mercury layer. The position of this excess oxygen might be slightly displaced from the (1/2 1/2 0) position. A 6% mercury deficiency is observed. Models, including mercury defects, substitution by copper cations, or carbonate groups, are compared. However, we obtain no definite evidence for either of the three models. A possible disorder of the Hg position, due to the formation of chemical bonds with neighbouring extra oxygen anions, could correlate to the refinements of mixed species at the Hg site. A low temperature single crystal x-ray diffraction study, and comparison of refinements for the same single crystal with different extra oxygen contents, are in progress to help clarify this problem.

Studies of O18 impurity trapping at interstitial dislocation loops in ion implanted Fe (1 1 0) by ion channeling and ab initio calculations

NASA Astrophysics Data System (ADS)

Mathayan, Vairavel; Kothalamuthu, Saravanan; Gnanasekaran, Jaiganesh; Balakrishnan, Sundaravel; Panigrahi, Binaykumar

2018-01-01

The O18 and self ions are implanted at same depth in Fe (1 1 0) crystal and annealed to study the oxygen trapping under excess self interstitial defects. Rutherford backscattering spectrometry, nuclear reaction analysis and channeling measurements have been performed to determine the lattice site position of O18. The presence of dislocation loops is confirmed by energy-dependent dechanneling parameter measurements. From the tilt angular scans of Fe and O18 signals along 〈1 0 0〉, 〈1 1 0〉 axes, O18 is found to be displaced 0.2 Å from tetrahedral towards octahedral interstitial site in O18. Similar lattice site location of oxygen with the displacement of 0.37 Å is predicted by density functional theory calculations for the interaction of oxygen with 〈1 0 0〉 interstitial dislocation loop structure. Our results provide strong evidence on oxygen trapping at interstitial dislocation loops in the presence of excess interstitial defects in iron.

Hypercapnic Respiratory Acidosis During An In-Flight Oxygen Assessment.

PubMed

Spurling, Kristofer J; Moonsie, Ian K; Perks, Joseph L

2016-02-01

Patients with respiratory disease are at risk of excessive hypoxemia in the hypobaric commercial aircraft cabin environment, and the consensus is that this is easily corrected with supplementary oxygen. However, despite the risks of hypercapnia with increasing inspired oxygen in some patients being well established, this issue is not currently addressed in medical guidelines for air travel. A 76-yr-old woman with chronic type 2 respiratory failure underwent hypoxic challenge testing (HCT) to assess in-flight oxygen requirements. She is stable on home ventilation, and baseline arterial blood gases showed mild hypoxemia (Pao2 9.12 kPa), normal P(a)co(2) (5.64 kPa) and pH (7.36) with 98% S(p)O(2). HCT was performed delivering 15% FIo(2) via a mask, and the patient desaturated to < 85%. HCT blood gases revealed significant hypoxemia (P(a)o(2) < 6.6 kPa), indicating in-flight oxygen. Continuous oxygen at 2 L · min⁻¹ via nasal cannula corrected the hypoxia, although P(a)co(2) increased to 6.9 kPa with reduction in pH to the threshold of severe respiratory acidosis (pH 7.25). The patient was advised against flying due to hypoxemia during HCT and the precipitous drop in pH on oxygen. It is possible to hyperoxygenate patients with type 2 respiratory failure in flight with the minimum level of supplementary oxygen available on many aircraft. In these cases P(a)co(2) and pH should be scrutinized during HCT before recommending in-flight oxygen. No current guidelines discuss the risk of hypercapnia from in-flight oxygen; it is therefore recommended that this be addressed in future revisions of medical air travel guidelines, should further research indicate it.

Excess-Si related defect centers in buried SiO2 thin films

NASA Astrophysics Data System (ADS)

Warren, W. L.; Fleetwood, D. M.; Shaneyfelt, M. R.; Schwank, J. R.; Winokur, P. S.; Devine, R. A. B.

1993-06-01

Using electron paramagnetic resonance (EPR) and capacitance-voltage measurements we have investigated the role of excess-silicon related defect centers as charge traps in separation by the implantation of oxygen materials. Three types of EPR-active centers were investigated: oxygen vacancy Eγ' centers (O3≡Si• +Si≡O3), delocalized Eδ' centers, and D centers (Si3≡Si•). It was found that all of these paramagnetic centers are created by selective hole injection, and are reasonably ascribed as positively charged when paramagnetic. These results provide the first experimental evidence for (1) the charge state of the Eδ' center, and (2) that the D center is an electrically active point defect in these materials.

Load cell verification of the uprated high pressure oxygen turbopump for the Space Shuttle Main Engine

NASA Technical Reports Server (NTRS)

Beatty, R. F.; Hine, M. J.

1986-01-01

The high pressure turbomachinery of the Space Shuttle Main Engine has the highest power-to-weight ratio of any operational machine known. Subsynchronous rotor whirl of the high pressure oxygen turbopump occurred in development testing at full-power level (109 percent thrust). The means by which the turbopump was successfully uprated is presented herein. The subsynchronous motion was determined to be driven by impeller destabilizing forces in combination with low net damping and bearing degradation. The degradation resulted from ball wear due primarily to an excessive loading condition of operating too near the lightly damped rotor second critical speed while under a large static load and, secondarily, from reverse bearing loading or loss of internal clearance and coolant during simulated flight conditions. The rotor response was reduced by stiffening the shaft and supports, optimizing the stiffness and damping of annular seals, and increasing the bearing deadband. The uprated oxygen turbopump configuration was verified by converting the pump and bearing support into a load cell for the purpose of systematically quantifying the load reduction benefits relative to baseline turbopumps. The damped second critical speed margin and the load sharing have been substantially improved which has resulted in reduced bearing loads for improved service life of the machine at full-power level.

Sensor materials for an intravascular fiber optic nitric oxide sensor

NASA Astrophysics Data System (ADS)

Soller, Babs R.; Parikh, Bhairavi R.; Stahl, Russell F.

1996-04-01

Nitric oxide (NO) is an important regulatory molecule in physiological processes including neurotransmission and the control of blood pressure. It is produced in excess during septic shock, the profound hypotensive state which accompanies severe infections. In-vivo measurement of NO would enhance the understanding of its varied biological roles. Our goal is the development of an intravascular fiber-optic sensor for the continuous measurement of NO. This study evaluated nitric oxide sensitive compounds as potential sensing materials in the presence and absence of oxygen. Using absorption spectroscopy we studied both the Fe II and Fe III forms of three biologically active hemes known to rapidly react with NO: hemoglobin, myoglobin, and cytochrome-c. The Fe II forms of hemoglobin and myoglobin and the Fe III form of cytochrome-c were found to have the highest sensitivity to NO. Cytochrome c (Fe III) is selective for NO even at high oxygen levels, while myoglobin is selective only under normal oxygen levels. NO concentrations as low as 1 (mu) M can be detected with our fiber-optic spectrometer using cytochrome c, and as low as 300 nM using myoglobin. Either of these materials would be adequate to monitor the increase in nitric oxide production during the onset of septic shock.

Paleoenvironmental History of Long Island Sound, CT, USA

NASA Astrophysics Data System (ADS)

Varekamp, J. C.; Thomas, E.; Lugolobi, F.; Buchholtz Ten Brink, M. R.

2002-12-01

Western Long Island Sound (LIS) is an urban estuary heavily impacted by waste water effluents from CT and New York city. The estuary has suffered seasonal hypoxia since the 1970s, and in 1999 lobsters suffered > 90% mortality. We used short sediment cores that cover the last several 100 years to reconstruct the temperature/salinity history of LIS, as well as its history of hypoxic episodes. We measured oxygen and carbon isotopic compositions and Mg/Ca and Sr/Ca in calcite tests of the benthic foraminifer Elphidium excavatum, collected alive (Rose Bengal stained) in grab samples and in core samples, as proxies for bottom water temperature and salinity. The level of bottom water oxygenation is derived from the carbon isotope values in foraminiferal calcite, after correction for paleosalinity. The strong seasonal temperature fluctuation in Long Island Sound bottom waters (about 20oC) and the long livespan of the foraminifer make precise paleotemperature estimates difficult. The oxygen isotope data (in vivo effect 1.1 o/_{oo} of the foraminiferal tests were recalculated at constant mean-annual water temperature (12.5^{o}C) into paleosalinities, ranging between 18 and 33 ^{o}/oo. The oxygen and carbon isotope ratios of river water, Long Island Sound water and dissolved inorganic carbon were used to construct a mixing model for the Sound. From calculated paleosalinities and the modern mixing model we derived expected carbon isotope ratios, which were subtracted from the observed values. We argue that the residuals (excess carbon isotope values) are proportional to the amount of organic carbon that was oxidized in these waters, and as such represent a proxy for paleohypoxia. Data from nine cores show no long term trends in salinity over the last 1000 years, but show more pronounced variations over the last 100 years. Several low salinity events could be correlated with wet climate periods documented in Southern New England. The excess carbon isotope values were between 0 and -1 o/_{oo} for most of the last millennium but became much more negative in the mid 18^{th} to 19^{th} century, with strong variability in the 20^{th} century. The low salinity events of the last 100 years correlate strongly with strongly negative excess carbon isotope values, suggesting a linkage between the wet periods and oxidation of organic matter on the bottom of the Sound (algal blooms, warm periods?). This linkage between low salinity events and strongly negative excess carbon isotope values did not occur prior to 1900 AD. More detailed dating (^{210}Pb, ^{137}$Cs) will improve the time resolution and correlation between cores of the various documented events.

Indoxyl sulfate potentiates endothelial dysfunction via reciprocal role for reactive oxygen species and RhoA/ROCK signaling in 5/6 nephrectomized rats.

PubMed

Chu, Shuang; Mao, Xiaodong; Guo, Hengjiang; Wang, Li; Li, Zezheng; Zhang, Yang; Wang, Yunman; Wang, Hao; Zhang, Xuemei; Peng, Wen

2017-03-01

Accumulative indoxyl sulfate (IS) retained in chronic kidney disease (CKD) can potentiate vascular endothelial dysfunction, and herein, we aim at elucidating the underlying mechanisms from the perspective of possible association between reactive oxygen species (ROS) and RhoA/ROCK pathway. IS-treated nephrectomized rats are administered with antioxidants including NADPH oxidase inhibitor apocynin, SOD analog tempol, and mitochondrion-targeted SOD mimetic mito-TEMPO to scavenge ROS, or ROCK inhibitor fasudil to obstruct RhoA/ROCK pathway. First, we find in response to IS stimulation, antioxidants treatments suppress increased aortic ROCK activity and expression levels. Additionally, ROCK blockade prevent IS-induced increased NADPH oxidase expression (mainly p22phox and p47phox), mitochondrial and intracellular ROS (superoxide and hydrogen peroxide) generation, and decreased Cu/Zn-SOD expression in thoracic aortas. Apocynin, mito-TEMPO, and tempol also reverse these markers of oxidative stress. These results suggest that IS induces excessive ROS production and ROCK activation involving a circuitous relationship in which ROS activate ROCK and ROCK promotes ROS overproduction. Finally, ROS and ROCK depletion attenuate IS-induced decrease in nitric oxide (NO) production and eNOS expression levels, and alleviate impaired vasomotor responses including increased vasocontraction to phenylephrine and decreased vasorelaxation to acetylcholine, thereby preventing cardiovascular complications accompanied by CKD. Taken together, excessive ROS derived from NADPH oxidase and mitochondria coordinate with RhoA/ROCK activation in a form of positive reciprocal relationship to induce endothelial dysfunction through disturbing endothelium-dependent NO signaling upon IS stimulation in CKD status.

Mitochondria-Targeted Antioxidant SkQ1 Improves Dermal Wound Healing in Genetically Diabetic Mice

PubMed Central

Demyanenko, Ilya A.; Zakharova, Vlada V.; Ilyinskaya, Olga P.; Vasilieva, Tamara V.; Fedorov, Artem V.; Skulachev, Vladimir P.

2017-01-01

Oxidative stress is widely recognized as an important factor in the delayed wound healing in diabetes. However, the role of mitochondrial reactive oxygen species in this process is unknown. It was assumed that mitochondrial reactive oxygen species are involved in many wound-healing processes in both diabetic humans and animals. We have applied the mitochondria-targeted antioxidant 10-(6′-plastoquinonyl)decyltriphenylphosphonium (SkQ1) to explore the role of mitochondrial reactive oxygen species in the wound healing of genetically diabetic mice. Healing of full-thickness excisional dermal wounds in diabetic C57BL/KsJ-db−/db− mice was significantly enhanced after long-term (12 weeks) administration of SkQ1. SkQ1 accelerated wound closure and stimulated epithelization, granulation tissue formation, and vascularization. On the 7th day after wounding, SkQ1 treatment increased the number of α-smooth muscle actin-positive cells (myofibroblasts), reduced the number of neutrophils, and increased macrophage infiltration. SkQ1 lowered lipid peroxidation level but did not change the level of the circulatory IL-6 and TNF. SkQ1 pretreatment also stimulated cell migration in a scratch-wound assay in vitro under hyperglycemic condition. Thus, a mitochondria-targeted antioxidant normalized both inflammatory and regenerative phases of wound healing in diabetic mice. Our results pointed to nearly all the major steps of wound healing as the target of excessive mitochondrial reactive oxygen species production in type II diabetes. PMID:28761623

Mitochondria-Targeted Antioxidant SkQ1 Improves Dermal Wound Healing in Genetically Diabetic Mice.

PubMed

Demyanenko, Ilya A; Zakharova, Vlada V; Ilyinskaya, Olga P; Vasilieva, Tamara V; Fedorov, Artem V; Manskikh, Vasily N; Zinovkin, Roman A; Pletjushkina, Olga Yu; Chernyak, Boris V; Skulachev, Vladimir P; Popova, Ekaterina N

2017-01-01

Oxidative stress is widely recognized as an important factor in the delayed wound healing in diabetes. However, the role of mitochondrial reactive oxygen species in this process is unknown. It was assumed that mitochondrial reactive oxygen species are involved in many wound-healing processes in both diabetic humans and animals. We have applied the mitochondria-targeted antioxidant 10-(6'-plastoquinonyl)decyltriphenylphosphonium (SkQ1) to explore the role of mitochondrial reactive oxygen species in the wound healing of genetically diabetic mice. Healing of full-thickness excisional dermal wounds in diabetic C57BL/KsJ-db - /db - mice was significantly enhanced after long-term (12 weeks) administration of SkQ1. SkQ1 accelerated wound closure and stimulated epithelization, granulation tissue formation, and vascularization. On the 7th day after wounding, SkQ1 treatment increased the number of α -smooth muscle actin-positive cells (myofibroblasts), reduced the number of neutrophils, and increased macrophage infiltration. SkQ1 lowered lipid peroxidation level but did not change the level of the circulatory IL-6 and TNF. SkQ1 pretreatment also stimulated cell migration in a scratch-wound assay in vitro under hyperglycemic condition. Thus, a mitochondria-targeted antioxidant normalized both inflammatory and regenerative phases of wound healing in diabetic mice. Our results pointed to nearly all the major steps of wound healing as the target of excessive mitochondrial reactive oxygen species production in type II diabetes.

OXYGEN DISSOCIATION OF WHOLE BLOOD STUDIED POLAROGRAPHICALLY

PubMed Central

Markus, Gabor; Baumberger, J. Percy

1952-01-01

The polarographic current of whole blood is in excess of that given by plasma at the same oxygen tension. The magnitude of this difference depends on (a) the oxygen content of the sample and thus is determined by the red blood cell content and by the state of oxygen saturation of hemoglobin, and (b) on the rate of dissociation of oxyhemoglobin and therefore is influenced by changes in pH, pCO2, and temperature. The total current at 37°C. is proportional to the oxygen content of the sample and can be used to determine the latter. The theoretical basis of the studied phenomena is discussed in detail. PMID:13011281

Expression of emotions and physiological changes during teaching

NASA Astrophysics Data System (ADS)

Tobin, Kenneth; King, Donna; Henderson, Senka; Bellocchi, Alberto; Ritchie, Stephen M.

2016-09-01

We investigated the expression of emotions while teaching in relation to a teacher's physiological changes. We used polyvagal theory (PVT) to frame the study of teaching in a teacher education program. Donna, a teacher-researcher, experienced high levels of stress and anxiety prior to beginning to teach and throughout the lesson we used her expressed emotions as a focus for this research. We adopted event-oriented inquiry in a study of heart rate, oxygenation of the blood, and expressed emotions. Five events were identified for multilevel analysis in which we used narrative, prosodic analysis, and hermeneutic-phenomenological methods to learn more about the expression of emotions when Donna had: high heart rate (before and while teaching); low blood oxygenation (before and while teaching); and high blood oxygenation (while teaching). What we learned was consistent with the body's monitoring system recognizing social harm and switching to the control of the unmyelinated vagus nerve, thereby shutting down organs and muscles associated with social communication—leading to irregularities in prosody and expression of emotion. In events involving high heart rate and low blood oxygenation the physiological environment was associated with less effective and sometimes confusing patterns in prosody, including intonation, pace of speaking, and pausing. In a low blood oxygenation environment there was evidence of rapid speech and shallow, irregular breathing. In contrast, during an event in which 100 % blood oxygenation occurred, prosody was perceived to be conducive to engagement and teacher expressed positive emotions, such as satisfaction, while teaching. Becoming aware of the purposes of the research and the results we obtained provided the teacher with tools to enact changes to her teaching practice, especially prosody of the voice. We regard it as a high priority to create tools to allow teachers and students, if and as necessary, to ameliorate excess emotions, and change heart rate, oxygenation levels, and breathing patterns.

Detailed studies of a high-capacity electrode material for rechargeable batteries, Li2MnO3-LiCo(1/3)Ni(1/3)Mn(1/3)O2.

PubMed

Yabuuchi, Naoaki; Yoshii, Kazuhiro; Myung, Seung-Taek; Nakai, Izumi; Komaba, Shinichi

2011-03-30

Lithium-excess manganese layered oxides, which are commonly described by the chemical formula zLi(2)MnO(3)-(1-z)LiMeO(2) (Me = Co, Ni, Mn, etc.), are of great importance as positive electrode materials for rechargeable lithium batteries. In this Article, Li(x)Co(0.13)Ni(0.13)Mn(0.54)O(2-δ) samples are prepared from Li(1.2)Ni(0.13)Co(0.13)Mn(0.54)O(2) (or 0.5Li(2)MnO(3)-0.5LiCo(1/3)Ni(1/3)Mn(1/3)O(2)) by an electrochemical oxidation/reduction process in an electrochemical cell to study a reaction mechanism in detail before and after charging across a voltage plateau at 4.5 V vs Li/Li(+). Changes of the bulk and surface structures are examined by synchrotron X-ray diffraction (SXRD), X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectroscopy (SIMS). SXRD data show that simultaneous oxygen and lithium removal at the voltage plateau upon initial charge causes the structural rearrangement, including a cation migration process from metal to lithium layers, which is also supported by XAS. This is consistent with the mechanism proposed in the literature related to the Li-excess manganese layered oxides. Oxygen removal associated with the initial charge on the high voltage plateau causes oxygen molecule generation in the electrochemical cells. The oxygen molecules in the cell are electrochemically reduced in the subsequent discharge below 3.0 V, leading to the extra capacity. Surface analysis confirms the formation of the oxygen containing species, such as lithium carbonate, which accumulates on the electrode surface. The oxygen containing species are electrochemically decomposed upon second charge above 4.0 V. The results suggest that, in addition to the conventional transition metal redox reactions, at least some of the reversible capacity for the Li-excess manganese layered oxides originates from the electrochemical redox reaction of the oxygen molecules at the electrode surface.

40 CFR 63.1203 - What are the standards for hazardous waste incinerators that are effective until compliance with...

Code of Federal Regulations, 2013 CFR

2013-07-01

... as propane; (6) Hydrochloric acid and chlorine gas in excess of 77 parts per million by volume, combined emissions, expressed as hydrochloric acid equivalents, dry basis and corrected to 7 percent oxygen... basis, corrected to 7 percent oxygen, and reported as propane; (6) Hydrochloric acid and chlorine gas in...

40 CFR 63.1203 - What are the standards for hazardous waste incinerators that are effective until compliance with...

Code of Federal Regulations, 2014 CFR

2014-07-01

... as propane; (6) Hydrochloric acid and chlorine gas in excess of 77 parts per million by volume, combined emissions, expressed as hydrochloric acid equivalents, dry basis and corrected to 7 percent oxygen... basis, corrected to 7 percent oxygen, and reported as propane; (6) Hydrochloric acid and chlorine gas in...

Relationship between energy dense diets and white adipose tissue inflammation in metabolic syndrome.

PubMed

Alemany, Marià

2013-01-01

Metabolic syndrome (MS) is a widespread pathologic state that manifests as multiple intertwined diseases affecting the entire body. This review analyzes the contribution of adipose tissue inflammation to its development. The main factor in the appearance of MS is an excess of dietary energy (largely fats), eliciting insulin resistance and creating the problem of excess energy disposal. Under these conditions, amino acid catabolism is diminished, which indirectly alters the production of nitric oxide and affects blood flow regulation. The oxidation of nitric oxide to nitrite and nitrate affects microbiota composition and functions. Adipose tissue cannot incorporate excessive nutrients after cell enlargement and loss of function. Tissue damage is a form of aggression, and the response is proinflammatory cytokine release. Cytokines favor the massive penetration of immune system cells, such as macrophages, which unsuccessfully try to fight an elusive danger for which they are not prepared. The consequence is low-level maintenance of the inflammatory state, which affects endoplasmic reticulum function and the endothelial response to excess regulatory mechanisms affecting blood flow and substrate/oxygen supply. When inflammation becomes chronic, the pathologic consequences are disseminated throughout the body because unused substrates and signals from adipose tissue affect energy partitioning and organ function. This maintenance of an unbalanced state ultimately results in the establishment of MS and associated pathologies. New research should focus on identifying ways to disarm the inflammatory response of adipose tissue when the dangers of dietary excess have already been controlled. Copyright © 2013. Published by Elsevier Inc.

Preventing and Treating Hypoxia: Using a Physiology Simulator to Demonstrate the Value of Pre-Oxygenation and the Futility of Hyperventilation.

PubMed

Lerant, Anna A; Hester, Robert L; Coleman, Thomas G; Phillips, William J; Orledge, Jeffrey D; Murray, W Bosseau

2015-01-01

Insufficient pre-oxygenation before emergency intubation, and hyperventilation after intubation are mistakes that are frequently observed in and outside the operating room, in clinical practice and in simulation exercises. Physiological parameters, as appearing on standard patient monitors, do not alert to the deleterious effects of low oxygen saturation on coronary perfusion, or that of low carbon dioxide concentrations on cerebral perfusion. We suggest the use of HumMod, a computer-based human physiology simulator, to demonstrate beneficial physiological responses to pre-oxygenation and the futility of excessive minute ventilation after intubation. We programmed HumMod, to A.) compare varying times (0-7 minutes) of pre-oxygenation on oxygen saturation (SpO2) during subsequent apnoea; B.) simulate hyperventilation after apnoea. We compared the effect of different minute ventilation rates on SpO2, acid-base status, cerebral perfusion and other haemodynamic parameters. A.) With no pre-oxygenation, starting SpO2 dropped from 98% to 90% in 52 seconds with apnoea. At the other extreme, following full pre-oxygenation with 100% O2 for 3 minutes or more, the SpO2 remained 100% for 7.75 minutes during apnoea, and dropped to 90% after another 75 seconds. B.) Hyperventilation, did not result in more rapid normalization of SpO2, irrespective of the level of minute ventilation. However, hyperventilation did cause significant decreases in cerebral blood flow (CBF). HumMod accurately simulates the physiological responses compared to published human studies of pre-oxygenation and varying post intubation minute ventilations, and it can be used over wider ranges of parameters than available in human studies and therefore available in the literature.

Preventing and Treating Hypoxia: Using a Physiology Simulator to Demonstrate the Value of Pre-Oxygenation and the Futility of Hyperventilation

PubMed Central

Lerant, Anna A.; Hester, Robert L.; Coleman, Thomas G.; Phillips, William J.; Orledge, Jeffrey D.; Murray, W. Bosseau

2015-01-01

Introduction: Insufficient pre-oxygenation before emergency intubation, and hyperventilation after intubation are mistakes that are frequently observed in and outside the operating room, in clinical practice and in simulation exercises. Physiological parameters, as appearing on standard patient monitors, do not alert to the deleterious effects of low oxygen saturation on coronary perfusion, or that of low carbon dioxide concentrations on cerebral perfusion. We suggest the use of HumMod, a computer-based human physiology simulator, to demonstrate beneficial physiological responses to pre-oxygenation and the futility of excessive minute ventilation after intubation. Methods: We programmed HumMod, to A.) compare varying times (0-7 minutes) of pre-oxygenation on oxygen saturation (SpO2) during subsequent apnoea; B.) simulate hyperventilation after apnoea. We compared the effect of different minute ventilation rates on SpO2, acid-base status, cerebral perfusion and other haemodynamic parameters. Results: A.) With no pre-oxygenation, starting SpO2 dropped from 98% to 90% in 52 seconds with apnoea. At the other extreme, following full pre-oxygenation with 100% O2 for 3 minutes or more, the SpO2 remained 100% for 7.75 minutes during apnoea, and dropped to 90% after another 75 seconds. B.) Hyperventilation, did not result in more rapid normalization of SpO2, irrespective of the level of minute ventilation. However, hyperventilation did cause significant decreases in cerebral blood flow (CBF). Conclusions: HumMod accurately simulates the physiological responses compared to published human studies of pre-oxygenation and varying post intubation minute ventilations, and it can be used over wider ranges of parameters than available in human studies and therefore available in the literature. PMID:26283881

Tailoring Materials for Mottronics: Excess Oxygen Doping of a Prototypical Mott Insulator.

PubMed

Scheiderer, Philipp; Schmitt, Matthias; Gabel, Judith; Zapf, Michael; Stübinger, Martin; Schütz, Philipp; Dudy, Lenart; Schlueter, Christoph; Lee, Tien-Lin; Sing, Michael; Claessen, Ralph

2018-05-07

The Mott transistor is a paradigm for a new class of electronic devices-often referred to by the term Mottronics-which are based on charge correlations between the electrons. Since correlation-induced insulating phases of most oxide compounds are usually very robust, new methods have to be developed to push such materials right to the boundary to the metallic phase in order to enable the metal-insulator transition to be switched by electric gating. Here, it is demonstrated that thin films of the prototypical Mott insulator LaTiO 3 grown by pulsed laser deposition under oxygen atmosphere are readily tuned by excess oxygen doping across the line of the band-filling controlled Mott transition in the electronic phase diagram. The detected insulator to metal transition is characterized by a strong change in resistivity of several orders of magnitude. The use of suitable substrates and capping layers to inhibit oxygen diffusion facilitates full control of the oxygen content and renders the films stable against exposure to ambient conditions. These achievements represent a significant advancement in control and tuning of the electronic properties of LaTiO 3+ x thin films making it a promising channel material in future Mottronic devices. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photodamage of a Mn(III/IV)-oxo mixed-valence compound and photosystem II: evidence that a high-valent manganese species is responsible for UV-induced photodamage of the oxygen-evolving complex in photosystem II.

PubMed

Wei, Zi; Cady, Clyde W; Brudvig, Gary W; Hou, Harvey J M

2011-01-01

The Mn cluster in photosystem II (PS II) is believed to play an important role in the UV photoinhibition of green plants, but the mechanism is still not clear at a molecular level. In this work, the photochemical stability of [Mn(III)(O)(2)Mn(IV)(H(2)O)(2)(Terpy)(2)](NO(3))(3) (Terpy=2,2':6',2''-terpyridine), designated as Mn-oxo mixed-valence dimer, a well characterized functional model of the oxygen-evolving complex in PS II, was examined in aqueous solution by exposing the complex to excess light irradiation at six different wavelengths in the range of 250 to 700 nm. The photodamage of the Mn-oxo mixed-valence dimer was confirmed by the decrease of its oxygen-evolution activity measured in the presence of the chemical oxidant oxone. Ultraviolet light irradiation induced a new absorption peak at around 400-440 nm of the Mn-oxo mixed-valence dimer. Visible light did not have the same effect on the Mn-oxo mixed-valence dimer. We speculate that the spectral change may be caused by conversion of the Mn(III)O(2)Mn(IV) dimer into a new structure--Mn(IV)O(2)Mn(IV). In the processes, the appearance of a 514 nm fluorescence peak was observed in the solution and may be linked to the hydration or protonation of Terpy ligand in the Mn-oxo dimer. In comparing the response of the PS II functional model compound and the PS II complex to excess light radiation, our results support the idea that UV photoinhibition is triggered at the Mn(4)Ca center of the oxygen-evolution complex in PS II by forming a modified structure, possibly a Mn(IV) species, and that the reaction of Mn ions is likely the initial step. Published by Elsevier B.V.

Reactive oxygen species and transcript analysis upon excess light treatment in wild-type Arabidopsis thaliana vs a photosensitive mutant lacking zeaxanthin and lutein

PubMed Central

2011-01-01

Background Reactive oxygen species (ROS) are unavoidable by-products of oxygenic photosynthesis, causing progressive oxidative damage and ultimately cell death. Despite their destructive activity they are also signalling molecules, priming the acclimatory response to stress stimuli. Results To investigate this role further, we exposed wild type Arabidopsis thaliana plants and the double mutant npq1lut2 to excess light. The mutant does not produce the xanthophylls lutein and zeaxanthin, whose key roles include ROS scavenging and prevention of ROS synthesis. Biochemical analysis revealed that singlet oxygen (1O2) accumulated to higher levels in the mutant while other ROS were unaffected, allowing to define the transcriptomic signature of the acclimatory response mediated by 1O2 which is enhanced by the lack of these xanthophylls species. The group of genes differentially regulated in npq1lut2 is enriched in sequences encoding chloroplast proteins involved in cell protection against the damaging effect of ROS. Among the early fine-tuned components, are proteins involved in tetrapyrrole biosynthesis, chlorophyll catabolism, protein import, folding and turnover, synthesis and membrane insertion of photosynthetic subunits. Up to now, the flu mutant was the only biological system adopted to define the regulation of gene expression by 1O2. In this work, we propose the use of mutants accumulating 1O2 by mechanisms different from those activated in flu to better identify ROS signalling. Conclusions We propose that the lack of zeaxanthin and lutein leads to 1O2 accumulation and this represents a signalling pathway in the early stages of stress acclimation, beside the response to ADP/ATP ratio and to the redox state of both plastoquinone pool. Chloroplasts respond to 1O2 accumulation by undergoing a significant change in composition and function towards a fast acclimatory response. The physiological implications of this signalling specificity are discussed. PMID:21481232

Effect of dissolved oxygen in alcoholic beverages and drinking water on alcohol elimination in humans.

PubMed

Rhee, Su-jin; Chae, Jung-woo; Song, Byung-jeong; Lee, Eun-sil; Kwon, Kwang-il

2013-02-01

Oxygen plays an important role in the metabolism of alcohol. An increased dissolved oxygen level in alcoholic beverages reportedly accelerates the elimination of alcohol. Therefore, we evaluated the effect of dissolved oxygen in alcohol and the supportive effect of oxygenated water on alcohol pharmacokinetics after the excessive consumption of alcohol, i.e., 540 ml of 19.5% alcohol (v/v). Fifteen healthy males were included in this randomized, 3 × 3 crossover study. Three combinations were tested: X, normal alcoholic beverage and normal water; Y, oxygenated alcoholic beverage and normal water; Z, oxygenated alcoholic beverage and oxygenated water. Blood alcohol concentrations (BACs) were determined by conversion of breath alcohol concentrations. Four pharmacokinetic parameters (C(max), T(max), K(el), and AUCall) were obtained using non-compartmental analysis and the times to reach 0.05% and 0.03% BAC (T(0.05%) and T(0.03%)) were compared using one-way analysis of variance (ANOVA) and Duncan's post hoc test. With combination Z, the BAC decreased to 0.05% significantly faster (p < 0.05) than with combination X. Analyzing the pharmacokinetic parameters, the mean K(el) was significantly higher for combination Z than for combinations X and Y (p < 0.05), whereas the mean values of C(max), T(max) and AUCall did not differ significantly among the combinations. Dissolved oxygen in drinks accelerates the decrease in BAC after consuming a large amount of alcohol. However, the oxygen dissolved in the alcoholic beverage alone did not have a sufficient effect in this case. We postulate that highly oxygenated water augments the effect of oxygen in the alcoholic beverage in alcohol elimination. Therefore, it is necessary to investigate the supportive effect of ingesting additional oxygenated water after heavy drinking of normal alcoholic beverages. Copyright © 2013 Elsevier Inc. All rights reserved.

Removing oxygen from a solvent extractant in an uranium recovery process

DOEpatents

Hurst, Fred J.; Brown, Gilbert M.; Posey, Franz A.

1984-01-01

An improvement in effecting uranium recovery from phosphoric acid solutions is provided by sparging dissolved oxygen contained in solutions and solvents used in a reductive stripping stage with an effective volume of a nonoxidizing gas before the introduction of the solutions and solvents into the stage. Effective volumes of nonoxidizing gases, selected from the group consisting of argon, carbon dioxide, carbon monoxide, helium, hydrogen, nitrogen, sulfur dioxide, and mixtures thereof, displace oxygen from the solutions and solvents thereby reduce deleterious effects of oxygen such as excessive consumption of elemental or ferrous and accumulation of complex iron phosphates or cruds.

Variable energy, high flux, ground-state atomic oxygen source

NASA Technical Reports Server (NTRS)

Chutjian, Ara (Inventor); Orient, Otto J. (Inventor)

1987-01-01

A variable energy, high flux atomic oxygen source is described which is comprised of a means for producing a high density beam of molecules which will emit O(-) ions when bombarded with electrons; a means of producing a high current stream of electrons at a low energy level passing through the high density beam of molecules to produce a combined stream of electrons and O(-) ions; means for accelerating the combined stream to a desired energy level; means for producing an intense magnetic field to confine the electrons and O(-) ions; means for directing a multiple pass laser beam through the combined stream to strip off the excess electrons from a plurality of the O(-) ions to produce ground-state O atoms within the combined stream; electrostatic deflection means for deflecting the path of the O(-) ions and the electrons in the combined stream; and, means for stopping the O(-) ions and the electrons and for allowing only the ground-state O atoms to continue as the source of the atoms of interest. The method and apparatus are also adaptable for producing other ground-state atoms and/or molecules.

Low-temperature solution-processed hydrogen molybdenum and vanadium bronzes for an efficient hole-transport layer in organic electronics.

PubMed

Xie, Fengxian; Choy, Wallace C H; Wang, Chuandao; Li, Xinchen; Zhang, Shaoqing; Hou, Jianhui

2013-04-11

A simple one-step method is reported to synthesize low-temperature solution-processed transition metal oxides (TMOs) of molybdenum oxide and vanadium oxide with oxygen vacancies for a good hole-transport layer (HTL). The oxygen vacancy plays an essential role for TMOs when they are employed as HTLs: TMO films with excess oxygen are highly undesirable for their application in organic electronics. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

17O excess transfer during the NO2 + O3 → NO3 + O2 reaction.

PubMed

Berhanu, Tesfaye Ayalneh; Savarino, Joël; Bhattacharya, S K; Vicars, Willliam C

2012-01-28

The ozone molecule possesses a unique and distinctive (17)O excess (Δ(17)O), which can be transferred to some of the atmospheric molecules via oxidation. This isotopic signal can be used to trace oxidation reactions in the atmosphere. However, such an approach depends on a robust and quantitative understanding of the oxygen transfer mechanism, which is currently lacking for the gas-phase NO(2) + O(3) reaction, an important step in the nocturnal production of atmospheric nitrate. In the present study, the transfer of Δ(17)O from ozone to nitrate radical (NO(3)) during the gas-phase NO(2) + O(3) → NO(3) + O(2) reaction was investigated in a series of laboratory experiments. The isotopic composition (δ(17)O, δ(18)O) of the bulk ozone and the oxygen gas produced in the reaction was determined via isotope ratio mass spectrometry. The Δ(17)O transfer function for the NO(2) + O(3) reaction was determined to be: Δ(17)O(O(3)∗) = (1.23 ± 0.19) × Δ(17)O(O(3))(bulk) + (9.02 ± 0.99). The intramolecular oxygen isotope distribution of ozone was evaluated and results suggest that the excess enrichment resides predominantly on the terminal oxygen atoms of ozone. The results obtained in this study will be useful in the interpretation of high Δ(17)O values measured for atmospheric nitrate, thus leading to a better understanding of the natural cycling of atmospheric reactive nitrogen. © 2012 American Institute of Physics

The triple oxygen isotope composition of phytoliths as a proxy of continental atmospheric humidity: insights from climate chamber and climate transect calibrations

NASA Astrophysics Data System (ADS)

Alexandre, Anne; Landais, Amarelle; Vallet-Coulomb, Christine; Piel, Clément; Devidal, Sébastien; Pauchet, Sandrine; Sonzogni, Corinne; Couapel, Martine; Pasturel, Marine; Cornuault, Pauline; Xin, Jingming; Mazur, Jean-Charles; Prié, Frédéric; Bentaleb, Ilhem; Webb, Elizabeth; Chalié, Françoise; Roy, Jacques

2018-05-01

Continental atmospheric relative humidity (RH) is a key climate parameter. Combined with atmospheric temperature, it allows us to estimate the concentration of atmospheric water vapor, which is one of the main components of the global water cycle and the most important gas contributing to the natural greenhouse effect. However, there is a lack of proxies suitable for reconstructing, in a quantitative way, past changes of continental atmospheric humidity. This reduces the possibility of making model-data comparisons necessary for the implementation of climate models. Over the past 10 years, analytical developments have enabled a few laboratories to reach sufficient precision for measuring the triple oxygen isotopes, expressed by the 17O-excess (17O-excess = ln (δ17O + 1) - 0.528 × ln (δ18O + 1)), in water, water vapor and minerals. The 17O-excess represents an alternative to deuterium-excess for investigating relative humidity conditions that prevail during water evaporation. Phytoliths are micrometric amorphous silica particles that form continuously in living plants. Phytolith morphological assemblages from soils and sediments are commonly used as past vegetation and hydrous stress indicators. In the present study, we examine whether changes in atmospheric RH imprint the 17O-excess of phytoliths in a measurable way and whether this imprint offers a potential for reconstructing past RH. For that purpose, we first monitored the 17O-excess evolution of soil water, grass leaf water and grass phytoliths in response to changes in RH (from 40 to 100 %) in a growth chamber experiment where transpiration reached a steady state. Decreasing RH from 80 to 40 % decreases the 17O-excess of phytoliths by 4.1 per meg/% as a result of kinetic fractionation of the leaf water subject to evaporation. In order to model with accuracy the triple oxygen isotope fractionation in play in plant water and in phytoliths we recommend direct and continuous measurements of the triple isotope composition of water vapor. Then, we measured the 17O-excess of 57 phytolith assemblages collected from top soils along a RH and vegetation transect in inter-tropical West and Central Africa. Although scattered, the 17O-excess of phytoliths decreases with RH by 3.4 per meg/%. The similarity of the trends observed in the growth chamber and nature supports that RH is an important control of 17O-excess of phytoliths in the natural environment. However, other parameters such as changes in the triple isotope composition of the soil water or phytolith origin in the plant may come into play. Assessment of these parameters through additional growth chambers experiments and field campaigns will bring us closer to an accurate proxy of changes in relative humidity.

Effects of pumpless extracorporeal lung assist on hemodynamics, gas exchange and inflammatory cascade response during experimental lung injury

PubMed Central

Ju, Zhihai; Ma, Jinhui; Wang, Chen; Yu, Jie; Qiao, Yeru; Hei, Feilong

2018-01-01

Pumpless extracorporeal lung assist (pECLA) has been reported to efficiently remove the systemic CO2 production and provide mild to moderate oxygenation, thereby allowing for ventilator settings and modes prioritizing oxygenation and lung protection. However, an adequate bypass flow, the capacity to provide respiratory support and the effect on the inflammatory cascade response and tissue perfusion require further study to be determined. After induction of acute lung injury (ALI) by oleic acid injection, pECLA was implemented in 12 anaesthetized and mechanically ventilated dogs for 48 h. Improved oxygenation [partial oxygen pressure (PaO2) and oxygen saturation (SaO2) was measured by arterial blood gas analysis, and increased by 29 and 18%, respectively] and CO2 elimination (partial CO2 pressure decreased by 43.35%) were obtained after pECLA implementation. A maximum arterio-venous shunt flow of up to 25% of the foundational CO resulted in stable hemodynamics. The pECLA procedure did not elicit any further increase in the concentration of tumor necrosis factor-α, interleukin (IL)-6, IL-8 and endothelin-1 compared with that in the group subjected to oleic acid injection only. In addition, the pECLA procedure had no effect on lactate levels and urine production. In conclusion, pECLA is an efficient and promising strategy for providing a mild to moderate oxygenation and adequate decarboxylation, while avoiding excessive inflammatory cascade response and tissue hypoperfusion in an experimental ALI model. PMID:29434789

Determining Glutathione Levels in Plants.

PubMed

Sahoo, Smita; Awasthi, Jay Prakash; Sunkar, Ramanjulu; Panda, Sanjib Kumar

2017-01-01

Upon exposure to abiotic stresses, plants tend to accumulate excessive amounts of reactive oxygen species (ROS) that inturn react with cellular lipids, proteins, and DNA. Therefore, decreasing ROS accumulation is indispensible to survive under stress, which is accomplished by inducing enzymatic and nonenzymatic antioxidant defense pathways. Glutathione, particularly reduced glutathione (GSH), represents a principal anitioxidant that could decrease ROS through scavenging them directly or indirectly through ascorbate-glutathione cycle or GSH peroxidases. Glutathione content can be determined using HPLC or spectrophotometric assays. In this chapter, we provided detailed assays to determine total, reduced, and oxidized gluathione using spectrophotometric method.

Influence of RF excitation during pulsed laser deposition in oxygen atmosphere on the structural properties and luminescence of nanocrystalline ZnO:Al thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meljanac, Daniel, E-mail: dmeljan@irb.hr; Plodinec, Milivoj; Siketić, Zdravko

2016-03-15

Thin ZnO:Al layers were deposited by pulsed laser deposition in vacuum and in oxygen atmosphere at gas pressures between 10 and 70 Pa and by applying radio-frequency (RF) plasma. Grazing incidence small angle x-ray scattering and grazing incidence x-ray diffraction (GIXRD) data showed that an increase in the oxygen pressure leads to an increase in the roughness, a decrease in the sample density, and changes in the size distribution of nanovoids. The nanocrystal sizes estimated from GIXRD were around 20 nm, while the sizes of the nanovoids increased from 1 to 2 nm with the oxygen pressure. The RF plasma mainly influenced themore » nanostructural properties and point defects dynamics. The photoluminescence consisted of three contributions, ultraviolet (UV), blue emission due to Zn vacancies, and red emission, which are related to an excess of oxygen. The RF excitation lowered the defect level related to blue emission and narrowed the UV luminescence peak, which indicates an improvement of the structural ordering. The observed influence of the deposition conditions on the film properties is discussed as a consequence of two main effects: the variation of the energy transfer from the laser plume to the growing film and changes in the growth chemistry.« less

Triple isotope composition of oxygen in atmospheric water vapor

NASA Astrophysics Data System (ADS)

Uemura, Ryu; Barkan, Eugeni; Abe, Osamu; Luz, Boaz

2010-02-01

Recently, an excess of 17O (17O-excess) has been demonstrated in meteoric water and ice cores. Based on theory and experiments, it has been suggested that this excess originates from evaporation of ocean water into under-saturated air. However, there has never been direct demonstration of this excess in marine vapor. Here, we present results of the first measurements of δ17O and δ18O in vapor samples collected over the South Indian and the Southern Oceans. Our data show the existence of 17O-excess in marine vapor and also clear negative correlation between 17O-excess and relative humidity. Thus, 17O-excess is useful for constraining oceanic humidity in hydrological and climatic models. Using the obtained values of 17O-excess, we estimated the fractionation factor between H218O and H216O for diffusion in air above the ocean (18αdiff). The new estimation of 18αdiff (1.008) is larger than the widely accepted value in hydrological studies.

Violaxanthin de-epoxidase is rate-limiting for non-photochemical quenching under subsaturating light or during chilling in Arabidopsis.

PubMed

Chen, Zhong; Gallie, Daniel R

2012-09-01

In response to conditions of excess light energy, plants induce non-photochemical quenching (NPQ) as a protective mechanism to prevent over reduction of photosystem II and the generation of reactive oxygen species (ROS). The xanthophyll cycle, which contributes significantly to reversible NPQ to thermally dissipate excess absorbed light energy, involves de-epoxidation of violaxanthin and antheraxanthin to zeaxanthin in response to excess light energy. The activation of violaxanthin de-epoxidase (VDE), which catalyzes the de-epoxidation reaction, requires the generation of a light-induced, transthylakoid pH gradient. In this work, we overexpressed or repressed the expression of VDE in Arabidopsis (Arabidopsis thaliana) to examine whether VDE is rate-limiting for the induction of NPQ. Increasing VDE expression increased the de-epoxidation state of xanthophyll pigments, the rate of NPQ induction, and the level of NPQ achieved under subsaturating light. In saturating light, however, overexpression of VDE did not increase the xanthophyll pigment de-epoxidation state, the level of NPQ achieved following its initial induction, or substantially improve tolerance to high light. Only under chilling, which reduces VDE activity, did an increase in VDE expression provide slightly greater phototolerance. Repression of VDE expression impaired violaxanthin de-epoxidation, reduced the generation of NPQ, and lowered the level of NPQ achieved while increasing photosensitivity. These results demonstrate that the endogenous level of VDE is rate-limiting for NPQ in Arabidopsis under subsaturating but not saturating light and can become rate-limiting under chilling conditions. These results also show that increasing VDE expression confers greater phototolerance mainly under conditions which limit endogenous VDE activity. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Autophagic Vacuolation Induced by Excess ROS Generation in HABP1/p32/gC1qR Overexpressing Fibroblasts and Its Reversal by Polymeric Hyaluronan

PubMed Central

Saha, Paramita; Chowdhury, Anindya Roy; Dutta, Shubhra; Chatterjee, Soumya; Ghosh, Ilora; Datta, Kasturi

2013-01-01

The ubiquitous hyaladherin, hyaluronan-binding protein 1 (HABP1/p32/gC1qR) upon stable overexpression in normal fibroblasts (F-HABP07) has been reported to induce mitochondrial dysfunction, growth retardation and apoptosis after 72 h of growth. HABP1 has been observed to accumulate in the mitochondria resulting in generation of excess Reactive Oxygen Species (ROS), mitochondrial Ca++ efflux and drop in mitochondrial membrane potential. In the present study, autophagic vacuolation was detected with monodansylcadaverin (MDC) staining from 36 h to 60 h of culture period along with elevated level of ROS in F-HABP07 cells. Increased expression of autophagic markers like MAP-LC3-II, Beclin 1 and autophagic modulator, DRAM confirmed the occurrence of the phenomenon. Reduced vacuole formation was observed upon treatment with 3-MA, a known PI3 kinase inhibitor, only at 32 h and was ineffective if treated later, as high ROS level was already attained. Treatment of F111 and F-HABP07 cells with bafilomycin A1 further indicated an increase in autophagosome formation along with autophagic degradation in HABP1 overexpressed fibroblasts. Comparison between normal fibroblast (F111) and F-HABP07 cells indicate reduced level of polymeric HA, its depolymerization and perturbed HA-HABP1 interaction in F-HABP07. Interestingly, supplementation of polymeric HA, an endogenous ROS scavenger, in the culture medium prompted reduction in number of vacuoles in F-HABP07 along with drop in ROS level, implying that excess ROS generation triggers initiation of autophagic vacuole formation prior to apoptosis due to overexpression of HABP1. Thus, the phenomenon of autophagy takes place prior to apoptosis induction in the HABP1 overexpressing cell line, F-HABP07. PMID:24205125

Escherichia coli Free Radical-Based Killing Mechanism Driven by a Unique Combination of Iron Restriction and Certain Antibiotics

PubMed Central

Ma, Li; Gao, Yongjun

2015-01-01

ABSTRACT Bacterial resistance to antibiotics is precipitating a medical crisis, and new antibacterial strategies are being sought. Hypothesizing that a growth-restricting strategy could be used to enhance the efficacy of antibiotics, we determined the effect of FDA-approved iron chelators and various antibiotic combinations on invasive and multidrug-resistant extraintestinal pathogenic Escherichia coli (ExPEC), the Gram-negative bacterium most frequently isolated from the bloodstreams of hospitalized patients. We report that certain antibiotics used at sublethal concentrations display enhanced growth inhibition and/or killing when combined with the iron chelator deferiprone (DFP). Inductively coupled plasma optical emission spectrometry reveals abnormally high levels of cell-associated iron under these conditions, a response that correlates with an iron starvation response and supraphysiologic levels of reactive oxygen species (ROS). The high ROS level is reversed upon the addition of antioxidants, which restores bacterial growth, suggesting that the cells are inhibited or killed by excessive free radicals. A model is proposed in which peptidoglycan-targeting antibiotics facilitate the entry of lethal levels of iron-complexed DFP into the bacterial cytoplasm, a process that drives the generation of ROS. This new finding suggests that, in addition to restriction of access to iron as a general growth-restricting strategy, targeting of cellular pathways or networks that selectively disrupt normal iron homeostasis can have potent bactericidal outcomes. IMPORTANCE The prospect that common bacteria will become resistant to all antibiotics is challenging the medical community. In addition to the development of next-generation antibiotics, new bacterial targets that display cytotoxic properties when altered need to be identified. Data presented here demonstrate that combining subinhibitory levels of both iron chelators and certain antibiotics kills pathogenic Escherichia coli. The mechanism of this effect is the production of supraphysiologic levels of reactive oxygen species, likely powered by the excessive import of iron. These findings were consistent for both clinically relevant and no longer clinically used antibiotics and may extend to Staphylococcus aureus as well. PMID:26391205

76 FR 46251 - Endangered and Threatened Wildlife and Plants; 12-Month Finding on a Petition To List the Redrock...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-02

... oxygen solubility (ability to be absorbed in water) increases as temperature decreases (Hauer and Hill... temperature and excessive nutrients that can lead to low dissolved oxygen. Several researchers have reported... DEPARTMENT OF THE INTERIOR Fish and Wildlife Service 50 CFR Part 17 [Docket No. FWS-R2-ES-2011...

Dynamics, Stability, and Adsorption States of Water on Oxidized RuO 2 (110)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Manh-Thuong; Mu, Rentao; Cantu, David C.

Identifying and understanding how excess oxygen atoms affect the adsorption of water on metal oxides is crucial for their use in water splitting. Here, by means of high-resolution scanning tunneling microscopy and density-functional calculations, we show that excess oxygen atoms on the stoichiometric RuO2(110) significantly change the clustering, conformation, and deprotonation equilibrium of adsorbed water. We considered two reactive scenarios during which the stoichiometric surface was exposed to: (i) first to oxygen followed by water, and (ii) first to water followed by oxygen. In both cases the [OH-OH] complex on Ru rows is the dominant species, showing a significant differencemore » from water-only adsorption on the stoichiometric surface in which the [OH-H2O] species is found to be prevalent. Surface reactivity at almost full O coverage is also addressed; there we show that site selectivity of the surface for H adsorption and dissociation of H2O is hindered, notwithstanding the increase of the dynamical motion of both species. We found that the work function of RuO2 can serve as a descriptor for the reactivity of this surface to water and its constituents.« less

Changes in Ocean Heat, Carbon Content, and Ventilation: A Review of the First Decade of GO-SHIP Global Repeat Hydrography.

PubMed

Talley, L D; Feely, R A; Sloyan, B M; Wanninkhof, R; Baringer, M O; Bullister, J L; Carlson, C A; Doney, S C; Fine, R A; Firing, E; Gruber, N; Hansell, D A; Ishii, M; Johnson, G C; Katsumata, K; Key, R M; Kramp, M; Langdon, C; Macdonald, A M; Mathis, J T; McDonagh, E L; Mecking, S; Millero, F J; Mordy, C W; Nakano, T; Sabine, C L; Smethie, W M; Swift, J H; Tanhua, T; Thurnherr, A M; Warner, M J; Zhang, J-Z

2016-01-01

Global ship-based programs, with highly accurate, full water column physical and biogeochemical observations repeated decadally since the 1970s, provide a crucial resource for documenting ocean change. The ocean, a central component of Earth's climate system, is taking up most of Earth's excess anthropogenic heat, with about 19% of this excess in the abyssal ocean beneath 2,000 m, dominated by Southern Ocean warming. The ocean also has taken up about 27% of anthropogenic carbon, resulting in acidification of the upper ocean. Increased stratification has resulted in a decline in oxygen and increase in nutrients in the Northern Hemisphere thermocline and an expansion of tropical oxygen minimum zones. Southern Hemisphere thermocline oxygen increased in the 2000s owing to stronger wind forcing and ventilation. The most recent decade of global hydrography has mapped dissolved organic carbon, a large, bioactive reservoir, for the first time and quantified its contribution to export production (∼20%) and deep-ocean oxygen utilization. Ship-based measurements also show that vertical diffusivity increases from a minimum in the thermocline to a maximum within the bottom 1,500 m, shifting our physical paradigm of the ocean's overturning circulation.

11-Oxygenated C19 Steroids Are the Predominant Androgens in Polycystic Ovary Syndrome.

PubMed

O'Reilly, Michael W; Kempegowda, Punith; Jenkinson, Carl; Taylor, Angela E; Quanson, Jonathan L; Storbeck, Karl-Heinz; Arlt, Wiebke

2017-03-01

Androgen excess is a defining feature of polycystic ovary syndrome (PCOS), but the exact origin of hyperandrogenemia remains a matter of debate. Recent studies have highlighted the importance of the 11-oxygenated C19 steroid pathway to androgen metabolism in humans. In this study, we analyzed the contribution of 11-oxygenated androgens to androgen excess in women with PCOS. One hundred fourteen women with PCOS and 49 healthy control subjects underwent measurement of serum androgens by liquid chromatography-tandem mass spectrometry. Twenty-four-hour urinary androgen excretion was analyzed by gas chromatography-mass spectrometry. Fasting plasma insulin and glucose were measured for homeostatic model assessment of insulin resistance. Baseline demographic data, including body mass index, were recorded. As expected, serum concentrations of the classic androgens testosterone (P < 0.001), androstenedione (P < 0.001), and dehydroepiandrosterone (P < 0.01) were significantly increased in PCOS. Mirroring this, serum 11-oxygenated androgens 11β-hydroxyandrostenedione, 11-ketoandrostenedione, 11β-hydroxytestosterone, and 11-ketotestosterone were significantly higher in PCOS than in control subjects, as was the urinary 11-oxygenated androgen metabolite 11β-hydroxyandrosterone. The proportionate contribution of 11-oxygenated to total serum androgens was significantly higher in patients with PCOS compared with control subjects [53.0% (interquartile range, 48.7 to 60.3) vs 44.0% (interquartile range, 32.9 to 54.9); P < 0.0001]. Obese (n = 51) and nonobese (n = 63) patients with PCOS had significantly increased 11-oxygenated androgens. Serum 11β-hydroxyandrostenedione and 11-ketoandrostenedione correlated significantly with markers of insulin resistance. We show that 11-oxygenated androgens represent the majority of circulating androgens in women with PCOS, with close correlation to markers of metabolic risk.

11-Oxygenated C19 Steroids Are the Predominant Androgens in Polycystic Ovary Syndrome

PubMed Central

O’Reilly, Michael W.; Kempegowda, Punith; Jenkinson, Carl; Taylor, Angela E.; Quanson, Jonathan L.; Storbeck, Karl-Heinz

2017-01-01

Context: Androgen excess is a defining feature of polycystic ovary syndrome (PCOS), but the exact origin of hyperandrogenemia remains a matter of debate. Recent studies have highlighted the importance of the 11-oxygenated C19 steroid pathway to androgen metabolism in humans. In this study, we analyzed the contribution of 11-oxygenated androgens to androgen excess in women with PCOS. Methods: One hundred fourteen women with PCOS and 49 healthy control subjects underwent measurement of serum androgens by liquid chromatography-tandem mass spectrometry. Twenty-four–hour urinary androgen excretion was analyzed by gas chromatography-mass spectrometry. Fasting plasma insulin and glucose were measured for homeostatic model assessment of insulin resistance. Baseline demographic data, including body mass index, were recorded. Results: As expected, serum concentrations of the classic androgens testosterone (P < 0.001), androstenedione (P < 0.001), and dehydroepiandrosterone (P < 0.01) were significantly increased in PCOS. Mirroring this, serum 11-oxygenated androgens 11β-hydroxyandrostenedione, 11-ketoandrostenedione, 11β-hydroxytestosterone, and 11-ketotestosterone were significantly higher in PCOS than in control subjects, as was the urinary 11-oxygenated androgen metabolite 11β-hydroxyandrosterone. The proportionate contribution of 11-oxygenated to total serum androgens was significantly higher in patients with PCOS compared with control subjects [53.0% (interquartile range, 48.7 to 60.3) vs 44.0% (interquartile range, 32.9 to 54.9); P < 0.0001]. Obese (n = 51) and nonobese (n = 63) patients with PCOS had significantly increased 11-oxygenated androgens. Serum 11β-hydroxyandrostenedione and 11-ketoandrostenedione correlated significantly with markers of insulin resistance. Conclusions: We show that 11-oxygenated androgens represent the majority of circulating androgens in women with PCOS, with close correlation to markers of metabolic risk. PMID:27901631

Subcellular Mn compartation, anatomic and biochemical changes of two grape varieties in response to excess manganese.

PubMed

Yao, Yinan; Xu, Gang; Mou, Dongling; Wang, Junru; Ma, Jinbiao

2012-09-01

To explore the underlying mechanism for the high tolerance to excess manganese stress in the grape species (Vitis vinifera Linn), we observed the subcellular compartment of Mn element, anatomic and biochemical responses of two grape cultivars (Combier and Shuijin) under excess Mn stress in semi-controlled environmental condition. Grape species exhibited typical detoxifying or tolerant mechanism as following: first, majority of Mn element accumulated in leaf was excluded into cell wall or comparted into cell vacuole to avoid cellular Mn-toxicity; Mn and other elements were also secreted into leaf surface or deposited in vascular wall; second, only small amount of Mn was located in cellular organ, and excess Mn in chloroplast was detoxified by depositing in starch granule, which serve as a novel detoxifying strategy; additionally, the cellular Mn was further chelated by phytochelatins; third, to quench the toxic oxygen radicals, the total phenolic compounds and polyamine (putrescine and spermidine) were enhanced. Although the obvious symptom of Mn-toxicity was not detected, we observed the dessication symptom under high level of Mn treatment in the two cultivars, such as sunk stomata, thickened palisade tissue, enhanced palisade/spongy tissue ratio and abscisic acid concentration. The growth inhibition and dessication symptom in the two grape cultivars could be largely associated with osmotic stress resulted from high concentration of leaf Mn. Copyright © 2012 Elsevier Ltd. All rights reserved.

Negative bias-and-temperature stress-assisted activation of oxygen-vacancy hole traps in 4H-silicon carbide metal-oxide-semiconductor field-effect transistors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ettisserry, D. P., E-mail: deva@umd.edu, E-mail: neil@umd.edu; Goldsman, N., E-mail: deva@umd.edu, E-mail: neil@umd.edu; Akturk, A.

We use hybrid-functional density functional theory-based Charge Transition Levels (CTLs) to study the electrical activity of near-interfacial oxygen vacancies located in the oxide side of 4H-Silicon Carbide (4H-SiC) power Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs). Based on the “amorphousness” of their local atomic environment, oxygen vacancies are shown to introduce their CTLs either within (permanently electrically active) or outside of (electrically inactive) the 4H-SiC bandgap. The “permanently electrically active” centers are likely to cause threshold voltage (V{sub th}) instability at room temperature. On the other hand, we show that the “electrically inactive” defects could be transformed into various “electrically active” configurations undermore » simultaneous application of negative bias and high temperature stresses. Based on this observation, we present a model for plausible oxygen vacancy defects that could be responsible for the recently observed excessive worsening of V{sub th} instability in 4H-SiC power MOSFETs under high temperature-and-gate bias stress. This model could also explain the recent electrically detected magnetic resonance observations in 4H-SiC MOSFETs.« less

Pharmacological models and approaches for pathophysiological conditions associated with hypoxia and oxidative stress.

PubMed

Farías, Jorge G; Herrera, Emilio A; Carrasco-Pozo, Catalina; Sotomayor-Zárate, Ramón; Cruz, Gonzalo; Morales, Paola; Castillo, Rodrigo L

2016-02-01

Hypoxia is the failure of oxygenation at the tissue level, where the reduced oxygen delivered is not enough to satisfy tissue demands. Metabolic depression is the physiological adaptation associated with reduced oxygen consumption, which evidently does not cause any harm to organs that are exposed to acute and short hypoxic insults. Oxidative stress (OS) refers to the imbalance between the generation of reactive oxygen species (ROS) and the ability of endogenous antioxidant systems to scavenge ROS, where ROS overwhelms the antioxidant capacity. Oxidative stress plays a crucial role in the pathogenesis of diseases related to hypoxia during intrauterine development and postnatal life. Thus, excessive ROS are implicated in the irreversible damage to cell membranes, DNA, and other cellular structures by oxidizing lipids, proteins, and nucleic acids. Here, we describe several pathophysiological conditions and in vivo and ex vivo models developed for the study of hypoxic and oxidative stress injury. We reviewed existing literature on the responses to hypoxia and oxidative stress of the cardiovascular, renal, reproductive, and central nervous systems, and discussed paradigms of chronic and intermittent hypobaric hypoxia. This systematic review is a critical analysis of the advantages in the application of some experimental strategies and their contributions leading to novel pharmacological therapies. Copyright © 2015 Elsevier Inc. All rights reserved.

Metabolic fate of glucose and candidate signaling and excess-fuel detoxification pathways in pancreatic β-cells

PubMed Central

Mugabo, Yves; Zhao, Shangang; Lamontagne, Julien; Al-Mass, Anfal; Peyot, Marie-Line; Corkey, Barbara E.; Joly, Erik; Madiraju, S. R. Murthy; Prentki, Marc

2017-01-01

Glucose metabolism promotes insulin secretion in β-cells via metabolic coupling factors that are incompletely defined. Moreover, chronically elevated glucose causes β-cell dysfunction, but little is known about how cells handle excess fuels to avoid toxicity. Here we sought to determine which among the candidate pathways and coupling factors best correlates with glucose-stimulated insulin secretion (GSIS), define the fate of glucose in the β-cell, and identify pathways possibly involved in excess-fuel detoxification. We exposed isolated rat islets for 1 h to increasing glucose concentrations and measured various pathways and metabolites. Glucose oxidation, oxygen consumption, and ATP production correlated well with GSIS and saturated at 16 mm glucose. However, glucose utilization, glycerol release, triglyceride and glycogen contents, free fatty acid (FFA) content and release, and cholesterol and cholesterol esters increased linearly up to 25 mm glucose. Besides being oxidized, glucose was mainly metabolized via glycerol production and release and lipid synthesis (particularly FFA, triglycerides, and cholesterol), whereas glycogen production was comparatively low. Using targeted metabolomics in INS-1(832/13) cells, we found that several metabolites correlated well with GSIS, in particular some Krebs cycle intermediates, malonyl-CoA, and lower ADP levels. Glucose dose-dependently increased the dihydroxyacetone phosphate/glycerol 3-phosphate ratio in INS-1(832/13) cells, indicating a more oxidized state of NAD in the cytosol upon glucose stimulation. Overall, the data support a role for accelerated oxidative mitochondrial metabolism, anaplerosis, and malonyl-CoA/lipid signaling in β-cell metabolic signaling and suggest that a decrease in ADP levels is important in GSIS. The results also suggest that excess-fuel detoxification pathways in β-cells possibly comprise glycerol and FFA formation and release extracellularly and the diversion of glucose carbons to triglycerides and cholesterol esters. PMID:28280244

Oxygen toxicity.

PubMed

Stogner, S W; Payne, D K

1992-12-01

The objective of this article is to provide an overview of the biochemistry of oxygen metabolism, including the formation of free radicals and the role of endogenous antioxidants. Pathophysiologic correlates underlying the clinical manifestations of oxygen toxicity are reviewed and management strategies are outlined. References from basic science and clinical journals were selected from the authors' files and from a search of a computerized database of the biomedical literature. Articles selected for review included both historical and current literature concerning the biochemistry and pathophysiology of oxygen toxicity in animals and humans. The benefits of oxygen therapy have been known for many years; however, its potential toxicity has not been recognized until the last two decades. The lungs, the eyes, and, under certain conditions, the central nervous system are the organs most affected by prolonged exposure to hyperoxic environments. Free radical formation during cellular metabolism under hyperoxic conditions is recognized as the biochemical basis of oxygen injury to cells and organs. Endogenous antioxidants are a primary means of detoxifying reactive oxygen species and preventing hyperoxia-induced cellular damage. When this defense fails or is overwhelmed by the excessive production of hyperoxia-induced free-radical species, distinctive morphologic changes occur at the cellular level. The amount of hyperoxia required to cause cellular damage and the time course of these changes vary from species to species and from individual to individual within the same species. Age, nutritional status, presence of underlying diseases, and certain drugs may influence the development of oxygen toxicity. There is currently no reliably effective drug for preventing or delaying the development of oxygen toxicity in humans. Use of the lowest effective oxygen concentration, the avoidance of certain drugs, and attention to nutritional and metabolic factors remain the best means currently available to avoid or minimize oxygen toxicity. Research is continuing into more effective ways to prevent, diagnose, and treat this disorder.

Antioxidative capacity and enzyme activity in Haematococcus pluvialis cells exposed to superoxide free radicals

NASA Astrophysics Data System (ADS)

Liu, Jianguo; Zhang, Xiaoli; Sun, Yanhong; Lin, Wei

2010-01-01

The antioxidative capacity of astaxanthin and enzyme activity of reactive oxygen eliminating enzymes such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) were studied in three cell types of Haematococcus pluvialis exposed to high concentrations of a superoxide anion radical (O{2/-}). The results show that defensive enzymes and astaxanthin-related mechanisms were both active in H. pluvialis during exposure to reactive oxygen species (ROS) such as O{2/-}. Astaxanthin reacted with ROS much faster than did the protective enzymes, and had the strongest antioxidative capacity to protect against lipid peroxidation. The defensive mechanisms varied significantly between the three cell types and were related to the level of astaxanthin that had accumulated in those cells. Astaxanthin-enriched red cells had the strongest antioxidative capacity, followed by brown cells, and astaxanthin-deficient green cells. Although there was no significant increase in expression of protective enzymes, the malondialdehyde (MDA) content in red cells was sustained at a low level because of the antioxidative effect of astaxanthin, which quenched O{2/-} before the protective enzymes could act. In green cells, astaxanthin is very low or absent; therefore, scavenging of ROS is inevitably reliant on antioxidative enzymes. Accordingly, in green cells, these enzymes play the leading role in scavenging ROS, and the expression of these enzymes is rapidly increased to reduce excessive ROS. However, because ROS were constantly increased in this study, the enhance enzyme activity in the green cells was not able to repair the ROS damage, leading to elevated MDA content. Of the four defensive enzymes measured in astaxanthin-deficient green cells, SOD eliminates O{2/-}, POD eliminates H2O2, which is a by-product of SOD activity, and APX and CAT are then initiated to scavenge excessive ROS.

Ground-Water Geochemistry of Kwajalein Island, Republic of the Marshall Islands, 1991

USGS Publications Warehouse

Tribble, Gordon W.

1997-01-01

Ground water on Kwajalein Island is an important source of drinking water, particularly during periods of low rainfall. Fresh ground water is found as a thin lens underlain by saltwater. The concentration of dissolved ions increases with depth below the water table and proximity to the shoreline as high-salinity seawater mixes with fresh ground water. The maximum depth of the freshwater lens is 37 ft. Chloride is assumed to be non-reactive under the range of geochemical conditions on the atoll. The concentration of chloride thus is used as a conservative constituent to evaluate freshwater-saltwater mixing within the aquifer. Concentrations of sodium and for the most part, potassium and sulfate, also appear to be determined by conservative mixing between saltwater and rain. Concentrations of calcium, magnesium, and strontium are higher than expected from conservative mixing; these higher concentrations are a result of the dissolution of carbonate minerals. An excess in dissolved inorganic carbon results from carbonate-mineral dissolution and from the oxidation of organic matter in the aquifer; the stoichiometric difference between excess dissolved inorganic carbon and excess bivalent cations is used as a measure of the amount of organic-matter oxidation. Organic-matter oxidation also is indicated by the low concentration of dissolved oxygen, high concentrations of nutrients, and the presence of hydrogen sulfide in many of the water samples. Low levels of dissolved oxygen indicate oxic respiration, and sulfate reduction is indicated by hydrogen sulfide. The amount of dissolved inorganic carbon released during organic-matter oxidation is nearly equivalent to the amount of carbonate-mineral dissolution. Organic-matter oxidation and carbonate-mineral dissolution seem to be most active either in the unsaturated zone or near the top of the water table. The most plausible explanation is that high amounts of oxic respiration in the unsaturated zone generate carbon dioxide, which causes carbonate minerals to dissolve. Ground water contaminated by petroleum hydrocarbons had the highest levels of mineral dissolution and organic respiration (including sulfate reduction), indicating that bacteria are oxidizing the contaminants.

Effect of exercise intensity on post-exercise oxygen consumption and heart rate recovery.

PubMed

Mann, Theresa N; Webster, Christopher; Lamberts, Robert P; Lambert, Michael I

2014-09-01

There is some evidence that measures of acute post-exercise recovery are sensitive to the homeostatic stress of the preceding exercise and these measurements warrant further investigation as possible markers of training load. The current study investigated which of four different measures of metabolic and autonomic recovery was most sensitive to changes in exercise intensity. Thirty-eight moderately trained runners completed 20-min bouts of treadmill exercise at 60, 70 and 80% of maximal oxygen uptake (VO2max) and four different recovery measurements were determined: the magnitude of excess post-exercise oxygen consumption (EPOCMAG), the time constant of the oxygen consumption recovery curve (EPOCτ), heart rate recovery within 1 min (HRR60s) and the time constant of the heart rate recovery curve (HRRτ) . Despite significant differences in exercise parameters at each exercise intensity, only EPOCMAG showed significantly slower recovery with each increase in exercise intensity at the group level and in the majority of individuals. EPOCτ was significantly slower at 70 and 80% of VO₂max vs. 60% VO₂max and HRRτ was only significantly slower when comparing the 80 vs. 60% VO₂max exercise bouts. In contrast, HRR60s reflected faster recovery at 70 and 80% of VO₂max than at 60% VO₂max. Of the four recovery measurements investigated, EPOCMAG was the most sensitive to changes in exercise intensity and shows potential to reflect changes in the homeostatic stress of exercise at the group and individual level. Determining EPOCMAG may help to interpret the homeostatic stress of laboratory-based research trials or training sessions.

[Performance of Electricity Generation and Feasibility of Discontinuous Power Supply of MFC by Using Pretreated Excess Sludge as Fuel].

PubMed

Zhao, Yan-hui; Zhao, Yang-guo; Guo, Liang

2016-03-15

The feasibility of treating pretreated excess sludge and capacity of supplying continuous power of microbial fuel cells (MFCs) were investigated. Two-chamber microbial fuel cells were started up and operated by using thermal pretreated excess sludge as the substrate. Potential fluctuations were achieved by changing the cathode electron acceptor. During the changes of electron acceptor, the operational stability of MFCs was assessed. The results indicated that the MFCs started successfully with oxygen as the cathode electron acceptor and reached 0.24 V after 148 hours. When the cathode electron acceptor was replaced by potassium ferricyanide, MFCs could obtain the maximum output voltage and maximum power density of 0.66 V and 4.21 W · m⁻³, respectively. When the cathode electron acceptor was changed from oxygen to potassium ferricyanide or the MFCs were closed circuit, the output power of MFCs recovered rapidly. In addition, changes of electron acceptor showed no effect on the removal of COD and ammonia nitrogen. Their removal efficiencies approached to 70% and 80%, respectively. This study concluded that MFC could treat the pretreated excess sludge and produce electricity simultaneously with a high power density. The MFC could also achieve discontinuous electricity supply during operation.

Method for oxygen reduction in a uranium-recovery process. [US DOE patent application

DOEpatents

Hurst, F.J.; Brown, G.M.; Posey, F.A.

1981-11-04

An improvement in effecting uranium recovery from phosphoric acid solutions is provided by sparging dissolved oxygen contained in solutions and solvents used in a reductive stripping stage with an effective volume of a nonoxidizing gas before the introduction of the solutions and solvents into the stage. Effective volumes of nonoxidizing gases, selected from the group consisting of argon, carbon dioxide, carbon monoxide, helium, hydrogen, nitrogen, sulfur dioxide, and mixtures thereof, displace oxygen from the solutions and solvents thereby reduce deleterious effects of oxygen such as excessive consumption of elemental or ferrous iron and accumulation of complex iron phosphates or cruds.

Combustor for a low-emissions gas turbine engine

DOEpatents

Glezer, Boris; Greenwood, Stuart A.; Dutta, Partha; Moon, Hee-Koo

2000-01-01

Many government entities regulated emission from gas turbine engines including CO. CO production is generally reduced when CO reacts with excess oxygen at elevated temperatures to form CO2. Many manufactures use film cooling of a combustor liner adjacent to a combustion zone to increase durability of the combustion liner. Film cooling quenches reactions of CO with excess oxygen to form CO2. Cooling the combustor liner on a cold side (backside) away from the combustion zone reduces quenching. Furthermore, placing a plurality of concavities on the cold side enhances the cooling of the combustor liner. Concavities result in very little pressure reduction such that air used to cool the combustor liner may also be used in the combustion zone. An expandable combustor housing maintains a predetermined distance between the combustor housing and combustor liner.

Highly stable CuO incorporated TiO(2) catalyst for photo-catalytic hydrogen production from H(2)O.

PubMed

Bandara, J; Udawatta, C P K; Rajapakse, C S K

2005-11-01

A CuO incorporated TiO(2) catalyst was found to be an active photo-catalyst for the reduction of H(2)O under sacrificial conditions. The catalytic activity originates from the photogeneration of excited electrons in the conduction bands of both TiO(2) and CuO resulting in a build-up of excess electrons in the conduction band of CuO. Consequently, the accumulation of excess electrons in CuO causes a negative shift in the Fermi level of CuO. The efficient inter-particle charge transfer leads to a higher catalytic activity and the formation of highly reduced states of TiO(2)/CuO, which are stable even under oxygen saturated condition. Negative shift in the Fermi level of CuO of the catalyst TiO(2)/CuO gains the required over-voltage necessary for efficient water reduction reaction. The function of CuO is to help the charge separation and to act as a water reduction site. The amount of CuO and crystalline structure were found to be crucial for the catalytic activity and the optimum CuO loading was ca. approximately 5-10%(w/w).

Pilot Plant Makes Oxygen Difluoride

NASA Technical Reports Server (NTRS)

Humphrey, Marshall F.; Lawton, Emil A.

1989-01-01

Pilot plant makes oxygen difluoride highly-energetic, space-storable oxidizer not made commercially. Designed to handle reactants, product, and byproduct, most of which highly reactive, corrosive, and toxic. Oxygen difluoride evolves continuously from reactor containing potassium hydroxide in water at 10 degree C. Collection tanks alternated; one filled while other drained to storage cylinder. Excess OF2 and F2 dissipated in combustion of charcoal in burn barrel. Toxic byproduct, potassium fluoride, reacted with calcium hydroxide to form nontoxic calcium fluoride and to regenerate potassium hydroxide. Equipment processes toxic, difficult-to-make substance efficiently and safely.

Methane Pyrolysis and Disposing Off Resulting Carbon

NASA Technical Reports Server (NTRS)

Sharma, P. K.; Rapp, D.; Rahotgi, N. K.

1999-01-01

Sabatier/Electrolysis (S/E) is a leading process for producing methane and oxygen for application to Mars ISPP. One significant problem with this process is that it produces an excess of methane for combustion with the amount of oxygen that is produced. Therefore, one must discard roughly half of the methane to obtain the proper stoichiometric methane/oxygen mixture for ascent from Mars. This is wasteful of hydrogen, which must be brought from Earth and is difficult to transport to Mars and store on Mars. To reduced the problem of transporting hydrogen to Mars, the S/E process can be augmented by another process which reduces overall hydrogen requirement. Three conceptual approaches for doing this are (1) recover hydrogen from the excess methane produced by the S/E process, (2) convert the methane to a higher hydrocarbon or other organic with a lower H/C ratio than methane, and (3) use a separate process (such as zirconia or reverse water gas shift reaction) to produce additional oxygen, thus utilizing all the methane produced by the Sabatier process. We report our results here on recovering hydrogen from the excess methane using pyrolysis of methane. Pyrolysis has the advantage that it produces almost pure hydrogen, and any unreacted methane can pass through the S/E process reactor. It has the disadvantage that disposing of the carbon produced by pyrolysis presents difficulties. Hydrogen may be obtained from methane by pyrolysis in the temperature range 10000-12000C. The main reaction products are hydrogen and carbon, though very small amounts of higher hydrocarbons, including aromatic hydrocarbons are formed. The conversion efficiency is about 95% at 12000C. One needs to distinguish between thermodynamic equilibrium conversion and conversion limited by kinetics in a finite reactor.

Extracellular calcium triggers unique transcriptional programs and modulates staurosporine-induced cell death in Neurospora crassa

PubMed Central

Gonçalves, A. P.; Monteiro, João; Lucchi, Chiara; Kowbel, David J.; Cordeiro, J. M.; Correia-de-Sá, Paulo; Rigden, Daniel J.; Glass, N. L.; Videira, Arnaldo

2014-01-01

Alterations in the intracellular levels of calcium are a common response to cell death stimuli in animals and fungi and, particularly, in the Neurospora crassa response to staurosporine. We highlight the importance of the extracellular availability of Ca2+ for this response. Limitation of the ion in the culture medium further sensitizes cells to the drug and results in increased accumulation of reactive oxygen species (ROS). Conversely, an approximately 30-fold excess of external Ca2+ leads to increased drug tolerance and lower ROS generation. In line with this, distinct staurosporine-induced cytosolic Ca2+ signaling profiles were observed in the absence or presence of excessive external Ca2+. High-throughput RNA sequencing revealed that different concentrations of extracellular Ca2+ define distinct transcriptional programs. Our transcriptional profiling also pointed to two putative novel Ca2+-binding proteins, encoded by the NCU08524 and NCU06607 genes, and provides a reference dataset for future investigations on the role of Ca2+ in fungal biology. PMID:28357255

Evaluation of bearing mounting design and excessive wear phenomena

NASA Technical Reports Server (NTRS)

Kannel, J. W.

1982-01-01

The effect of bearing thermal growth on the effectiveness of the bearing preload springs on the space shuttle main engine high pressure oxygen turbopump (SSME HPTOP) were examined. The SSME HPTOP turbine end bearings, preload spring, and bearing mounting design were evaluated relative to spalling, excessive ball wear, possible thermal problems, and cage delamination. The magnitude of the thermal stresses required to cause high levels of ball wear were calculated. Plots of maximum sheer stress and maximum reversing shear versus the axial load for the 57 mm SSME HPTOP bearing were created. A plot of the bearing thermal growth versus preload spring deflection was generated. It was determined that metallic wear, rather than thermal growth, caused enlargement of the contact zone between ball and races, that high fatigue-inducing shear stresses are generated under increased loads, and that at temperatures between 100 and 150 deg C, the springs bottom out and very high loads are developed in the bearing. Allowance for adequate spring movement after assembly is recommended.

Predictors of treatment failure for non-severe childhood pneumonia in developing countries--systematic literature review and expert survey--the first step towards a community focused mHealth risk-assessment tool?

PubMed

McCollum, Eric D; King, Carina; Hollowell, Robert; Zhou, Janet; Colbourn, Tim; Nambiar, Bejoy; Mukanga, David; Burgess, Deborah C Hay

2015-07-09

Improved referral algorithms for children with non-severe pneumonia at the community level are desirable. We sought to identify predictors of oral antibiotic failure in children who fulfill the case definition of World Health Organization (WHO) non-severe pneumonia. Predictors of greatest interest were those not currently utilized in referral algorithms and feasible to obtain at the community level. We systematically reviewed prospective studies reporting independent predictors of oral antibiotic failure for children 2-59 months of age in resource-limited settings with WHO non-severe pneumonia (either fast breathing for age and/or lower chest wall indrawing without danger signs), with an emphasis on predictors not currently utilized for referral and reasonable for community health workers. We searched PubMed, Cochrane, and Embase and qualitatively analyzed publications from 1997-2014. To supplement the limited published evidence in this subject area we also surveyed respiratory experts. Nine studies met criteria, seven of which were performed in south Asia. One eligible study occurred exclusively at the community level. Overall, oral antibiotic failure rates ranged between 7.8-22.9%. Six studies found excess age-adjusted respiratory rate (either WHO-defined very fast breathing for age or 10-15 breaths/min faster than normal WHO age-adjusted thresholds) and four reported young age as predictive for oral antibiotic failure. Of the seven predictors identified by the expert panel, abnormal oxygen saturation and malnutrition were most highly favored per the panel's rankings and comments. This review identified several candidate predictors of oral antibiotic failure not currently utilized in childhood pneumonia referral algorithms; excess age-specific respiratory rate, young age, abnormal oxygen saturation, and moderate malnutrition. However, the data was limited and there are clear evidence gaps; research in rural, low-resource settings with community health workers is needed.

High glucose-induced excessive reactive oxygen species promote apoptosis through mitochondrial damage in rat cartilage endplate cells.

PubMed

Jiang, Zengxin; Lu, Wei; Zeng, Qingmin; Li, Defang; Ding, Lei; Wu, Jingping

2018-04-16

Diabetes mellitus (DM) is an important factor in intervertebral disc degeneration (IDD). Apoptosis of cartilage endplate (CEP) cells is one of the initiators of IDD. However, the effects of high glucose on CEP cells are still unknown. Therefore, we conducted the present study to evaluate the effects of high glucose on CEP cells and to identify the mechanisms of those effects. Rat CEP cells were isolated and cultured in 10% foetal bovine serum (FBS, normal control) or high-glucose medium (10% FBS + 0.1 M glucose or 10% FBS + 0.2 M glucose, experimental conditions) for 1 or 3 days. In addition, CEP cells were treated with 0.2 M glucose for 3 days in the presence or absence of alpha-lipoic acid (ALA, 0.15 M). Flow cytometry was performed to identify and quantify the degree of apoptosis. The expression of reactive oxygen species (ROS) was assessed by flow cytometry, and mitochondrial damage (mitochondrial membrane potential) was assessed by fluorescence microscopy. Furthermore, the expression levels of cleaved caspase-3, cleaved caspase-9, Bcl-2, Bax, and cytochrome c were evaluated by Western blotting. High glucose significantly increased apoptosis and ROS accumulation in CEP cells in a dose- and time-dependent manner. Meanwhile, a disrupted mitochondrial membrane potential was detected in rat CEP cells cultured in the two high glucose concentrations. Incubating in high glucose enhanced the expression levels of cleaved caspase-3, cleaved caspase-9, Bax, and cytochrome c but decreased the level of the anti-apoptotic protein Bcl-2. ALA inhibited the expression of cleaved caspase-3, cleaved caspase-9, Bax, and cytochrome c but enhanced the expression of Bcl-2. ALA also prevented disruption of the mitochondrial membrane potential in CEP cells. This study demonstrates that high glucose-induced excessive reactive oxygen species promote mitochondrial damage, thus causing apoptosis in rat CEP cells in a dose- and time-dependent manner. ALA could prevent mitochondrial damage and apoptosis caused by high glucose in CEP cells. The results suggest that appropriate blood glucose control may be the key to preventing IDD in diabetic patients. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Absorption process for producing oxygen and nitrogen and solution therefor

DOEpatents

Roman, Ian C.

1984-01-01

Process for the separation and purification of oxygen and nitrogen is disclosed which utilizes solutions of oxygen carriers to selectively absorb oxygen from a gaseous stream, leaving nitrogen as a byproduct. In the process, an oxygen carrier capable of reversibly binding molecular oxygen is dissolved in a solvent solution, which absorbs oxygen from an oxygen-containing gaseous feed stream such as atmospheric air and desorbs oxygen to a gaseous product stream. The feed stream is maintained at a sufficiently high oxygen pressure to keep the oxygen carrier in its oxygenated form during absorption, while the product stream is maintained at a sufficiently low oxygen pressure to keep the carrier in its deoxygenated form during desorption. In an alternate mode of operation, the carrier solution is maintained at a sufficiently low temperature and high oxygen pressure to keep the oxygen carrier in its oxygenated form during absorption, and at a sufficiently high temperature to keep the carrier in its deoxygenated form during desorption. Under such conditions, exceptionally high oxygen concentrations on the order of 95% to 99% are obtained, as well as a long carrier lifetime in excess of 3 months, making the process commercially feasible.

Absorption process for producing oxygen and nitrogen and solution therefor

DOEpatents

Roman, Ian C. [Wilmington, DE; Baker, Richard W. [Palo Alto, CA

1990-09-25

Process for the separation and purification of oxygen and nitrogen is disclosed which utilizes solutions of oxygen carriers to selectively absorb oxygen from a gaseous stream, leaving nitrogen as a byproduct. In the process, an oxygen carrier capable of reversibly binding molecular oxygen is dissolved in a solvent solution, which absorbs oxygen from an oxygen-containing gaseous feed stream such as atmospheric air and desorbs oxygen to a gaseous product stream. The feed stream is maintained at a sufficiently high oxygen pressure to keep the oxygen carrier in its oxygenated form during absorption, while the product stream is maintained at a sufficiently low oxygen pressure to keep the carrier in its deoxygenated form during desorption. In an alternate mode of operation, the carrier solution is maintained at a sufficiently low temperature and high oxygen pressure to keep the oxygen carrier in its oxygenated form during absorption, and at a sufficiently high temperature to keep the carrier in its deoxygenated form during desorption. Under such conditions, exceptionally high oxygen concentrations on the order of 95% to 99% are obtained, as well as a long carrier lifetime in excess of 3 months, making the process commercially feasible.

Absorption process for producing oxygen and nitrogen and solution therefor

DOEpatents

Roman, I.C.; Baker, R.W.

1990-09-25

Process for the separation and purification of oxygen and nitrogen is disclosed which utilizes solutions of oxygen carriers to selectively absorb oxygen from a gaseous stream, leaving nitrogen as a byproduct. In the process, an oxygen carrier capable of reversibly binding molecular oxygen is dissolved in a solvent solution, which absorbs oxygen from an oxygen-containing gaseous feed stream such as atmospheric air and desorbs oxygen to a gaseous product stream. The feed stream is maintained at a sufficiently high oxygen pressure to keep the oxygen carrier in its oxygenated form during absorption, while the product stream is maintained at a sufficiently low oxygen pressure to keep the carrier in its deoxygenated form during desorption. In an alternate mode of operation, the carrier solution is maintained at a sufficiently low temperature and high oxygen pressure to keep the oxygen carrier in its oxygenated form during absorption, and at a sufficiently high temperature to keep the carrier in its deoxygenated form during desorption. Under such conditions, exceptionally high oxygen concentrations on the order of 95% to 99% are obtained, as well as a long carrier lifetime in excess of 3 months, making the process commercially feasible. 1 figure

[What degree of hypoxemia is tolerable for human beings?].

PubMed

Köhler, D

2010-03-01

According to the literature, hypoxemia is considered to be severe when oxygen saturation (Sa O(2)) falls below 90 %. Frequently one can discover lower values without impairment of the patient. Especially patients with the obesity hypoventilation syndrome (OHS) will have frequent night time desaturations of significant duration below 50 % Sa O(2), but do still cope with their daytime jobs. This discrepancy can only be explained by the fact, that hypoxemia is not equivalent to tissue hypoxia. The latter is mainly being determined by oxygen delivery (DO2) which is being calculated by multiplying cardiac output (CO) and oxygen content (CaO2). Ca O(2) is determined by the product of Sa O(2) and haemoglobin (Hb) times 1.35. From this context it becomes evident, that assessing hypoxemia without considering oxygen content will frequently be misleading. The human organism has several possible ways of compensation in order to avoid tissue hypoxia. In case of acute hypoxemia that evolves within minutes the organism can shift the oxygen binding curve by changing 2 - 3-DGP erythrocytic activity. Additionally non vital organ systems might reduce their oxygen uptake. During sustained hypoxia (lasting 2 - 3 days) the Krebs cycle and the respiratory chain will express hypoxia-resistant iso-enzymes. Long lasting hypoxia can be compensated by polycythemia. Indirect data suggest, that the critical number for the oxygen content is rather low and is estimated to be somewhere around 33 % of the normal value. These mechanism of hypoxia-resistance are hardly ever maxed out in patients on critical care units.Lack of knowledge of the above described mechanisms does frequently result in diseases like ARDS which frequently develops due to excessive ventilatory pressures and excessive inspired O(2) concentrations. Georg Thieme Verlag KG Stuttgart, New York.

Super-reduced polyoxometalates: excellent molecular cluster battery components and semipermeable molecular capacitors.

PubMed

Nishimoto, Yoshio; Yokogawa, Daisuke; Yoshikawa, Hirofumi; Awaga, Kunio; Irle, Stephan

2014-06-25

Theoretical investigations are presented on the molecular and electronic structure changes that occur as α-Keggin-type polyoxometalate (POM(3-)) clusters [PM12O40](3-) (M = Mo, W) are converted toward their super-reduced POM(27-) state during the discharging process in lithium-based molecular cluster batteries. Density functional theory was employed in geometry optimization, and first-principles molecular dynamics simulations were used to explore local minima on the potential energy surface of neutral POM clusters adorned with randomly placed Li atoms as electron donors around the cluster surface. On the basis of structural, electron density, and molecular orbital studies, we present evidence that the super-reduction is accompanied by metal-metal bond formation, beginning from the 12th to 14th excess electron transferred to the cluster. Afterward, the number of metal-metal bonds increases nearly linearly with the number of additionally transferred excess electrons. In α-Keggin-type POMs, metal triangles are a prominently emerging structural feature. The origin of the metal triangle formation during super-reduction stems from the formation of characteristic three-center two-electron bonds in triangular metal atom sites, created under preservation of the POM skeleton via "squeezing out" of oxygen atoms bridging two metal atoms when the underlying metal atoms form covalent bonds. The driving force for this unusual geometrical and electronic structure change is a local Jahn-Teller distortion at individual transition-metal octahedral sites, where the triply degenerate t2 d orbitals become partially filled during reduction and gain energy by distortion of the octahedron in such a way that metal-metal bonds are formed. The bonding orbitals show strong contributions from mixing with metal-oxygen antibonding orbitals, thereby "shuffling away" excess electrons from the cluster center to the outside of the cage. The high density of negatively charged yet largely separated oxygen atoms on the surface of the super-reduced POM(27-) polyanion allows the huge Coulombic repulsion due to the presence of the excess electrons to be counterbalanced by the presence of Li countercations, which partially penetrate into the outer oxygen shell. This "semiporous molecular capacitor" structure is likely the reason for the effective electron uptake in POMs.

Quantification and characterization of greywater from schools.

PubMed

Alsulaili, Abdalrahman D; Hamoda, Mohamed F

2015-01-01

Survey of schools of different education levels (primary, intermediate and secondary) in Kuwait showed an average greywater generation rate of 7.3 L/p/d and varied in the range of 2.9-16 l/p/d, reflecting the school level of education (i.e. student age). The highest rates were observed for primary schools while the lowest rates were observed in secondary schools where students are more mature and use the water more wisely. The greywater characteristics indicated waste with low chemical oxygen demand (COD) and 5-day biochemical oxygen demand (BOD5) values but relatively high solids, conductivity, and sodium content due to excessive use of hand soap. Total coliform values ranged between 89 and 352 most probable number (MPN)/mL with an average of 196 MPN/mL while no fecal coliform values were detected. Greywater collected from schools is classified as light greywater and contains much lower levels of organic matter and nutrients compared to residential greywater and domestic wastewater. It is suitable for non-potable reuse after minimal treatment since microbial contamination may pose a serious threat to health if greywater comes into contact with humans. It also provides a good opportunity for reuse in toilet flushing since it can be easily collected from wash sinks and fountains, as major sources, and recycled.

Cost-effective control of nitrogen loadings in Long Island Sound

NASA Astrophysics Data System (ADS)

Bennett, Lynne L.; Thorpe, Steven G.; Guse, A. Joseph

2000-12-01

Long Island Sound is plagued by conditions of severe hypoxia (low levels of dissolved oxygen) during the summer months because of the existence of excessive amounts of nitrogen. A new proposal that would allow sewage treatment plants to buy or sell nitrogen discharge credits is currently being evaluated by the states of Connecticut and New York. Existing theory suggests that a trading program for nitrogen emissions would be a cost-effective means of addressing the problem. We estimate the costs associated with several trading scenarios and find that the potential for cost savings is substantial and that cost savings rise as the scope of trading expands.

Controlling Oxygen Mobility in Ruddlesden–Popper Oxides

PubMed Central

Lee, Dongkyu; Lee, Ho Nyung

2017-01-01

Discovering new energy materials is a key step toward satisfying the needs for next-generation energy conversion and storage devices. Among the various types of oxides, Ruddlesden–Popper (RP) oxides (A2BO4) are promising candidates for electrochemical energy devices, such as solid oxide fuel cells, owing to their attractive physicochemical properties, including the anisotropic nature of oxygen migration and controllable stoichiometry from oxygen excess to oxygen deficiency. Thus, understanding and controlling the kinetics of oxygen transport are essential for designing optimized materials to use in electrochemical energy devices. In this review, we first discuss the basic mechanisms of oxygen migration in RP oxides depending on oxygen nonstoichiometry. We then focus on the effect of changes in the defect concentration, crystallographic orientation, and strain on the oxygen migration in RP oxides. We also briefly review their thermal and chemical stability. Finally, we conclude with a perspective on potential research directions for future investigation to facilitate controlling oxygen ion migration in RP oxides. PMID:28772732

Reactive Oxygen Species in the Regulation of Synaptic Plasticity and Memory

PubMed Central

Klann, Eric

2011-01-01

Abstract The brain is a metabolically active organ exhibiting high oxygen consumption and robust production of reactive oxygen species (ROS). The large amounts of ROS are kept in check by an elaborate network of antioxidants, which sometimes fail and lead to neuronal oxidative stress. Thus, ROS are typically categorized as neurotoxic molecules and typically exert their detrimental effects via oxidation of essential macromolecules such as enzymes and cytoskeletal proteins. Most importantly, excessive ROS are associated with decreased performance in cognitive function. However, at physiological concentrations, ROS are involved in functional changes necessary for synaptic plasticity and hence, for normal cognitive function. The fine line of role reversal of ROS from good molecules to bad molecules is far from being fully understood. This review focuses on identifying the multiple sources of ROS in the mammalian nervous system and on presenting evidence for the critical and essential role of ROS in synaptic plasticity and memory. The review also shows that the inability to restrain either age- or pathology-related increases in ROS levels leads to opposite, detrimental effects that are involved in impairments in synaptic plasticity and memory function. Antioxid. Redox Signal. 14, 2013–2054. PMID:20649473

Whey protein enhances normal inflammatory responses during cutaneous wound healing in diabetic rats

PubMed Central

2011-01-01

Background Prolonged wound healing is a complication of diabetes that contributes to mortality. Impaired wound healing occurs as a consequence of excessive reactive oxygen species (ROS) production. Whey protein (WP) is able to reduce the oxygen radicals and increase the levels of the antioxidant glutathione. Thus, the aim of this study was to determine whether dietary supplementation with WP could enhance normal inflammatory responses during wound healing in diabetic rats. Animals were assigned into a wounded control group (WN), a wounded diabetic group (WD) and a wounded diabetic group orally supplemented with whey protein (WDWP) at a dose of 100 mg/kg body weight. Results Whey protein was found to significantly decrease the levels of malondialdehyde (MDA), nitric oxide (NO) and ROS. A significant restoration of the glutathione level was observed in WDWP rats. During the early wound healing stage, IL-1β, TNF-α, IL-6, IL-4 and neutrophil infiltration were significantly decreased in WD mice. WP supplementation was found to restore the levels of these inflammatory markers to the levels observed in control animals. In addition, the time required for wound healing was significantly prolonged in diabetic rats. WP was found to significantly decrease the time required for wound healing in WDWP rats. Conclusion In conclusion, dietary supplementation with WP enhances the normal inflammatory responses during wound healing in diabetic mice by restoring the levels of oxidative stress and inflammatory cytokines. PMID:22168406

Nitrification of raw or used water using expanded bed biofilm reactor technology.

PubMed

Dempsey, M J

2011-01-01

Excessive ammonia in raw water increases the consumption of chlorine for disinfection during production of potable water, through oxidation to produce chloramines. Excessive ammonia in used water results in pollution of the aquatic environment, where it is particularly toxic to fish. Furthermore, nitrifying prokaryotes in the receiving water will consume dissolved oxygen equivalent to 4.6 g oxygen per g ammonia-nitrogen oxidized to nitrate. This places a considerable oxygen demand on the receiving water and can result in anoxic conditions. One solution to these problems is to nitrify the ammonia in a dedicated biological process. As nitrifiers are particularly slow growing, they are easily washed out of conventional water and wastewater treatment processes; hence, the use of immobilized biomass in an expanded bed biofilm reactor. This solution typically allows at least 10-times the biomass concentration of conventional systems, with a similar decrease in bioreactor size or increase in bioreactor productivity. This chapter describes expanded bed technology for nitrification of water, and methods for studying biomass and process performance. Copyright © 2011 Elsevier Inc. All rights reserved.

Impact of Continuous Positive Airway Pressure Treatment on Leptin Levels in Patients with Obstructive Sleep Apnea Syndrome.

PubMed

Yosunkaya, Şebnem; Okur, Hacer Kuzu; Can, Ümmügülsüm; Zamani, Adil; Kutlu, Ruhuşen

2015-08-01

There is growing evidence that leptin regulation is altered in obstructive sleep apnea syndrome (OSAS). Several potential mechanisms have been purported to explain how sleep apnea may alter leptin levels. We investigated whether repeated apneas, hypoxia, or excessive daytime sleepiness influenced the levels of leptin in OSAS patients. We also evaluated whether a 3-month continuous positive airway pressure (CPAP) treatment affected leptin levels in patients. Randomly selected 31 untreated, otherwise healthy male, overweight [body mass index (BMI) >25 kg/m(2)] obstructive sleep apnea syndrome (OSAS) patients [apnea-hypopnea index (AHI) ≥15] and 25 control (AHI <5) were included in this study. To confirm the diagnosis, all subjects underwent standard polysomnography. Serum samples were taken at 07:00-08:00 a.m. after overnight fasting. The OSAS patients that had regular CPAP treatment (n=26) were re-evaulated 3 months later. Leptin levels (50.5±17.5 grams/L in OSAS and 56.3±25.5 grams/L in controls) and lipid profiles (TC, TGs, HDL-C, and LDL-C) between patient and control groups did not differ (P>0.05). Leptin levels were not correlated with the AHI, oxygen saturation, or excessive daytime sleepiness. CPAP treatment did not significantly change the (BMI), waist and neck circumference, or leptin levels in OSAS patients. Furthermore, we found no correlation between the decrease in serum leptin levels and parameters that were improved by CPAP treatment. Leptin levels and lipid profile of overweight subjects with and without OSAS were not different, and our results suggest that OSAS-related parameters and CPAP treatment do not play a significant role in the serum leptin levels.

Aerobic glycolysis during brain activation: adrenergic regulation and influence of norepinephrine on astrocytic metabolism.

PubMed

Dienel, Gerald A; Cruz, Nancy F

2016-07-01

Aerobic glycolysis occurs during brain activation and is characterized by preferential up-regulation of glucose utilization compared with oxygen consumption even though oxygen level and delivery are adequate. Aerobic glycolysis is a widespread phenomenon that underlies energetics of diverse brain activities, such as alerting, sensory processing, cognition, memory, and pathophysiological conditions, but specific cellular functions fulfilled by aerobic glycolysis are poorly understood. Evaluation of evidence derived from different disciplines reveals that aerobic glycolysis is a complex, regulated phenomenon that is prevented by propranolol, a non-specific β-adrenoceptor antagonist. The metabolic pathways that contribute to excess utilization of glucose compared with oxygen include glycolysis, the pentose phosphate shunt pathway, the malate-aspartate shuttle, and astrocytic glycogen turnover. Increased lactate production by unidentified cells, and lactate dispersal from activated cells and lactate release from the brain, both facilitated by astrocytes, are major factors underlying aerobic glycolysis in subjects with low blood lactate levels. Astrocyte-neuron lactate shuttling with local oxidation is minor. Blockade of aerobic glycolysis by propranolol implicates adrenergic regulatory processes including adrenal release of epinephrine, signaling to brain via the vagus nerve, and increased norepinephrine release from the locus coeruleus. Norepinephrine has a powerful influence on astrocytic metabolism and glycogen turnover that can stimulate carbohydrate utilization more than oxygen consumption, whereas β-receptor blockade 're-balances' the stoichiometry of oxygen-glucose or -carbohydrate metabolism by suppressing glucose and glycogen utilization more than oxygen consumption. This conceptual framework may be helpful for design of future studies to elucidate functional roles of preferential non-oxidative glucose utilization and glycogen turnover during brain activation. Aerobic glycolysis, the preferential up-regulation of glucose utilization (CMRglc ) compared with oxygen consumption (CMRO2 ) during brain activation, is blocked by propranolol. Epinephrine release from the adrenal gland stimulates vagus nerve signaling to the locus coeruleus, enhancing norepinephrine release in the brain, and regulation of astrocytic and neuronal metabolism to stimulate CMRglc more than CMRO2 . Propranolol suppresses CMRglc more than CMRO2 . © 2016 International Society for Neurochemistry.

Evolution of flexible non-photochemical quenching mechanisms that regulate light harvesting in oxygenic photosynthesis.

PubMed

Niyogi, Krishna K; Truong, Thuy B

2013-06-01

All photosynthetic organisms need to regulate light harvesting for photoprotection. Three types of flexible non-photochemical quenching (NPQ) mechanisms have been characterized in oxygenic photosynthetic cyanobacteria, algae, and plants: OCP-, LHCSR-, and PSBS-dependent NPQ. OCP-dependent NPQ likely evolved first, to quench excess excitation in the phycobilisome (PB) antenna of cyanobacteria. During evolution of eukaryotic algae, PBs were lost in the green and secondary red plastid lineages, while three-helix light-harvesting complex (LHC) antenna proteins diversified, including LHCSR proteins that function in dissipating excess energy rather than light harvesting. PSBS, an independently evolved member of the LHC protein superfamily, seems to have appeared exclusively in the green lineage, acquired a function as a pH sensor that turns on NPQ, and eventually replaced LHCSR in vascular plants. Copyright © 2013 Elsevier Ltd. All rights reserved.

Azoxystrobin-induced excessive reactive oxygen species (ROS) production and inhibition of photosynthesis in the unicellular green algae Chlorella vulgaris.

PubMed

Liu, Lei; Zhu, Bin; Wang, Gao-Xue

2015-05-01

This study investigated the short-term toxicity of azoxystrobin (AZ), one of strobilurins used as an effective fungicidal agent to control the Asian soybean rust, on aquatic unicellular algae Chlorella vulgaris. The median percentile inhibition concentration (IC₅₀) of AZ for C. vulgaris was found to be 510 μg L(-1). We showed that the algal cells were obviously depressed or shrunk in 300 and 600 μg L(-1) AZ treatments by using the electron microscopy. Furthermore, 19, 75, and 300 μg L(-1) AZ treatments decreased the soluble protein content and chlorophyll concentrations in C. vulgaris and altered the energy-photosynthesis-related mRNA expression levels in 48- and 96-h exposure periods. Simultaneously, our results showed that AZ could increase the total antioxidant capacity (T-AOC) level and compromise superoxide dismutase (SOD), peroxidase (POD), glutathione S transferase (GST), glutathione peroxidase (GPx) activities, and glutathione (GSH) content. These situations might render C. vulgaris more vulnerable to oxidative damage. Overall, the present study indicated that AZ might be toxic to the growth of C. vulgaris, affect energy-photosynthesis-related mRNA expressions, and induce reactive oxygen species (ROS) overproduction in C. vulgaris.

Feasibility tests of nickel as a containment material of molten Li2O-LiCl salt containing Li metal at 650 °C during electrolytic reduction

NASA Astrophysics Data System (ADS)

Choi, Eun-Young; Lee, Jeong

2017-11-01

In this study, we investigated the feasibility of nickel (Ni) as a material to contain molten Li2O-LiCl salt containing lithium (Li) metal at 650 °C as an electrolyte during the electrolytic reduction process of pyroprocessing (also known as oxide reduction, OR). First, the behaviors of Ni in four different LiCl salts (0.1 wt% Li-LiCl, 1 and 8 wt% Li2O-LiCl, and 8 wt% Li2O-0.1 wt% Li-LiCl) in an argon atmosphere were examined through immersion tests. Then, Ni was used as a vessel material for five consecutive OR runs of simulated oxide fuel using 1.0 wt% Li2O-LiCl salt. The tested Ni was analyzed by microbalance, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Concentrations of Ni in the salt were measured using inductively coupled plasma atomic emission spectroscopy. No corrosion product of Ni, except Cr2Ni3, was observed on the Ni used for both the salt-immersion tests and the OR runs because the Ni was not exposed to oxygen gas. However, leaching of Ni in the OR salt containing excessive Li metal was observed. Therefore, Ni can be used as the salt containment material in the OR process when excessive Li metal and oxygen gas in the salt are maintained at low levels.

Understanding the Origins of Higher Capacities at Faster Rates in Lithium-Excess Li xNi 2–4x/3Sb x/3O 2

DOE PAGES

Twu, Nancy; Metzger, Michael; Balasubramanian, Mahalingam; ...

2017-02-08

Here, the lithium-excess Li xNi 2-4x/3Sb x/3O 2 (LNSO) materials were previously shown to demonstrate higher capacities and improved cyclability with increasing lithium content. While the performance trend is promising, observed capacities are much lower than theoretical capacities, pointing to a need for further understanding of active redox processes in these materials. In this work, we study the electrochemical behavior of the LNSO materials as a function of lithium content and at slow and fast rates. Surprisingly, Li 1.15Ni 0.47Sb 0.38O 2 (LNSO-15) exhibits higher discharge capacities at faster rates and traverses distinct voltage curves at slow and fast rates.more » To understand these two peculiarities, we characterize the redox activity of nickel, antimony, and oxygen at different rates. While experiments confirm some nickel redox activity and oxygen loss, these two mechanisms cannot account for all observed capacity. We propose that the balance of the observed capacity may be due reversible oxygen redox and that the rate-dependent voltage curve features may derive from irreversible nickel migration occurring on slow charge. As future high energy density cathodes are likely to contain both lithium excess and high nickel content, both of these findings have important implications for the development of novel high capacity cathode materials.« less

Oxygen Partial Pressure Impact on Characteristics of Indium Titanium Zinc Oxide Thin Film Transistor Fabricated via RF Sputtering

PubMed Central

Hsu, Ming-Hung; Chang, Sheng-Po; Chang, Shoou-Jinn; Wu, Wei-Ting; Li, Jyun-Yi

2017-01-01

Indium titanium zinc oxide (InTiZnO) as the channel layer in thin film transistor (TFT) grown by RF sputtering system is proposed in this work. Optical and electrical properties were investigated. By changing the oxygen flow ratio, we can suppress excess and undesirable oxygen-related defects to some extent, making it possible to fabricate the optimized device. XPS patterns for O 1s of InTiZnO thin films indicated that the amount of oxygen vacancy was apparently declined with the increasing oxygen flow ratio. The fabricated TFTs showed a threshold voltage of −0.9 V, mobility of 0.884 cm2/Vs, on-off ratio of 5.5 × 105, and subthreshold swing of 0.41 V/dec. PMID:28672868

Oxygen Partial Pressure Impact on Characteristics of Indium Titanium Zinc Oxide Thin Film Transistor Fabricated via RF Sputtering.

PubMed

Hsu, Ming-Hung; Chang, Sheng-Po; Chang, Shoou-Jinn; Wu, Wei-Ting; Li, Jyun-Yi

2017-06-26

Indium titanium zinc oxide (InTiZnO) as the channel layer in thin film transistor (TFT) grown by RF sputtering system is proposed in this work. Optical and electrical properties were investigated. By changing the oxygen flow ratio, we can suppress excess and undesirable oxygen-related defects to some extent, making it possible to fabricate the optimized device. XPS patterns for O 1s of InTiZnO thin films indicated that the amount of oxygen vacancy was apparently declined with the increasing oxygen flow ratio. The fabricated TFTs showed a threshold voltage of -0.9 V, mobility of 0.884 cm²/Vs, on-off ratio of 5.5 × 10⁵, and subthreshold swing of 0.41 V/dec.

Burning experiments and late Paleozoic high O2 levels

NASA Astrophysics Data System (ADS)

Wildman, R.; Essenhigh, R.; Berner, R.; Hickey, L.; Wildman, C.

2003-04-01

The Paleozoic rise of land plants brought about increased burial of organic matter and a resulting increase in atmospheric oxygen concentrations. Levels as high as 30-35% O2 may have been reached during the Permo-Carboniferous (Berner and Canfield, 1989; Berner, 2001). However, burning experiments based solely on paper (Watson, 1978) have challenged these results, the claim being that if the oxygen made up more than 25% of the atmosphere, the frequency and intensity of forest fires would increase sufficiently to prevent the continued existence of plant life. Thus, since plants have persisted, it is possible that fires served as a negative feedback against excessive oxygen levels. An initial study of Paleozoic wildfire behavior via thermogravimetric analysis (TGA) was conducted under ambient and enriched oxygen conditions to simulate present and ancient atmospheres. The tests focused on natural fuels, specifically tree leaves and wood, tree fern fibers, and sphagnum peat-moss, simulating Permo-Carboniferous upland and swampland ecosystems, respectively. Three conclusions are: (1) enriched oxygen increases the rate of mass loss during burning; (2) fuel chemistry (cellulose vs. lignin) influences burning patterns; and (3) in geometrically heterogeneous fuels, geometry affects burning rate significantly. Both geometrically and chemically, paper resists fire poorly; thus, we found that it loses its mass at lower temperatures than forest materials and is therefore a poor proxy for Paleozoic ecosystems. Further study of Paleozoic wildfire spread behavior is currently being conducted. Fires are lit using pine dowels, which allow for reproducible fuel density. Steady-state, one-dimensional flame-spread is measured with thermocouples anchored two inches above the fuel bed. Both oxygen concentration of the air supply to the fire and moisture content of the fuels are varied, as we suspect that these are two main controls of wildfire spread. Burning fuels of varying moisture contents is central to this study, for fuel moisture is a fire retardant that may offset the fire-enhancing effects of high oxygen conditions. Earliest preliminary results at low moisture show that, as expected, increasing oxygen concentration significantly increases the rate of fuel consumption. This is expressed as both an increase in the speed of the flame spread and the temperature of the flames. It was found that a 35% oxygen (balance nitrogen) gas mixture caused fire to spread at about five times the rate of a fire in ambient air. The fire in the high-oxygen gas mixture was roughly 1.3 times the temperature of the fire in ambient air. The current work is not intended to exactly represent forest ecosystems; rather, it is intended to establish an understanding of flame-spread behavior in natural fuels and future work will include fuels that better represent natural ecosystems such as those used in the TGA experimentation.

Hydrogen Fluxes from Photosynthetic Communities: Implications for Early Earth Biogeochemistry

NASA Technical Reports Server (NTRS)

Hoehler, Tori M.; Bebout, Brad M.; DesMarais, David J.; DeVincenzi, Donald L. (Technical Monitor)

2000-01-01

More than half the history of life on Earth was dominated by photosynthetic microbial mats, which must have represented the preeminent biological influence on global geochemical cycling during that time. In modem analogs of then ancient communities, hypersaline microbial mats from Guerrero Negro, Mexico, we have observed a large flux of molecular hydrogen originating in the cyanobacteria-dominated surface layers. Hydrogen production follows a distinct diel pattern and is sensitive to both oxygen tension and microbial species composition within the mat. On an early Earth dominated by microbial mats, the observed H2 fluxes would scale to global levels far in excess of geothermal emissions. A hydrogen flux of this magnitude represents a profound transmission of reducing power from oxygenic photosynthesis, both to the anaerobic biosphere, where H2 is an almost universally-utilized substrate and regulator of microbial redox chemistry, and to the atmosphere, where subsequent escape to space could provide an important mechanism for the net oxidation of Earth's surface.

Decidualized Human Endometrial Stromal Cells Mediate Hemostasis, Angiogenesis, and Abnormal Uterine Bleeding

PubMed Central

Lockwood, Charles J.; Krikun, Graciela; Hickey, Martha; Huang, S. Joseph; Schatz, Frederick

2011-01-01

Factor VII binds trans-membrane tissue factor to initiate hemostasis by forming thrombin. Tissue factor expression is enhanced in decidualized human endometrial stromal cells during the luteal phase. Long-term progestin only contraceptives elicit: 1) abnormal uterine bleeding from fragile vessels at focal bleeding sites, 2) paradoxically high tissue factor expression at bleeding sites; 3) reduced endometrial blood flow promoting local hypoxia and enhancing reactive oxygen species levels; and 4) aberrant angiogenesis reflecting increased stromal cell-expressed vascular endothelial growth factor, decreased Angiopoietin-1 and increased endothelial cell-expressed Angiopoietin-2. Aberrantly high local vascular permeability enhances circulating factor VII to decidualized stromal cell-expressed tissue factor to generate excess thrombin. Hypoxia-thrombin interactions augment expression of vascular endothelial growth factor and interleukin-8 by stromal cells. Thrombin, vascular endothelial growth factor and interlerukin-8 synergis-tically augment angiogenesis in a milieu of reactive oxygen species-induced endothelial cell activation. The resulting enhanced vessel fragility promotes abnormal uterine bleeding. PMID:19208784

Cascade heat recovery with coproduct gas production

DOEpatents

Brown, William R.; Cassano, Anthony A.; Dunbobbin, Brian R.; Rao, Pradip; Erickson, Donald C.

1986-01-01

A process for the integration of a chemical absorption separation of oxygen and nitrogen from air with a combustion process is set forth wherein excess temperature availability from the combustion process is more effectively utilized to desorb oxygen product from the absorbent and then the sensible heat and absorption reaction heat is further utilized to produce a high temperature process stream. The oxygen may be utilized to enrich the combustion process wherein the high temperature heat for desorption is conducted in a heat exchange preferably performed with a pressure differential of less than 10 atmospheres which provides considerable flexibility in the heat exchange.

Excess Oxygen Defects in Layered Cuprates

DOE R&D Accomplishments Database

Lightfoot, P.; Pei, S. Y.; Jorgensen, J. D.; Manthiram, A.; Tang, X. X.; Goodenough, J. B.

1990-09-01

Neutron powder diffraction has been used to study the oxygen defect chemistry of two non-superconducting layered cuprates, La{sub 1. 25}Dy{sub 0.75}Cu{sub 3.75}F{sub 0.5}, having a T{sup {asterisk}}- related structure, and La{sub 1.85}Sr{sub 1.15}Cu{sub 2}O{sub 6.25}, having a structure related to that of the newly discovered double-layer superconductor La{sub 2-x}Sr{sub x}CaCu{sub 2}O{sub 6}. The role played by oxygen defects in determining the superconducting properties of layered cuprates is discussed.

Microbial nitrogen sinks in the water column of a large coastal hypoxic area, the Gulf of Mexico "Dead Zone"

NASA Astrophysics Data System (ADS)

Rogener, M. K.; Roberts, B. J.; Rabalais, N. N.; Stewart, F. J.; Joye, S. B.

2016-02-01

Excess nitrogen in coastal environments leads to eutrophication, harmful algal blooms, habitat loss, oxygen depletion and reductions in biodiversity. As such, biological nitrogen (N) removal through the microbially-mediated process of denitrification is a critical ecosystem function that can mitigate the negative consequences of excess nitrogen loading. However, denitrification can produce nitrous oxide, a potent greenhouse gas, as a byproduct under some environmental conditions. To understand how excess nitrogen loading impacts denitrification, we measured rates of this process in the water column of the Gulf of Mexico "Dead Zone" three times over the summer of 2015. The Dead Zone is generated by excessive nitrogen loading from the Mississippi River co-occurring with strong water column stratification, which leads to a large summer-time hypoxic/anoxic area at the mouth of the river and along the coast of Louisiana. Rates of denitrification ranged from 31 to 153 nmol L-1 d-1. Dead Zone waters are also enriched in methane and aerobic methane oxidation rates ranged from 0.1 to 4.3 nmol L-1 d-1. Maximal denitrification rates were observed at stations with the lowest oxygen concentrations and highest methane oxidation rates, suggesting a potential coupling between nitrate reduction and methane oxidation which both scrubs reactive N and methane from the system, thus performing a duel ecosystem service.

Air Force Studies Board Block 00 Studies

DTIC Science & Technology

2016-07-14

effectively in efforts aimed at reducing energy consumption . Without more data on energy use, “You don’t know what you don’t know.” The question was raised...with Oxygen Trim Maintain Excess Oxygen Below 5%, Below 8% for Stokers Reduce Stack Temperature to 330°F for Sulfur Bearing Fuels Minimize...current approaches to industrial process energy with a goal of highlighting potential ways to reduce Air Force industrial process energy consumption .1

40 CFR 63.6675 - What definitions apply to this subpart?

Code of Federal Regulations, 2011 CFR

2011-07-01

..., in a two-step reaction, promotes the conversion of excess oxygen, NOX, CO, and volatile organic... reciprocating motion to convert heat energy into mechanical work and which is not mobile. Stationary RICE differ...

Quantitative clarification of inactivation mechanism of Penicillium digitatum spores treated with neutral oxygen radicals

NASA Astrophysics Data System (ADS)

Hashizume, Hiroshi; Ohta, Takayuki; Takeda, Keigo; Ishikawa, Kenji; Hori, Masaru; Ito, Masafumi

2015-01-01

We have quantitatively investigated the oxidative inactivation process of Penicillium digitatum spores including intracellular nanostructural changes through neutral oxygen species with a flux-defined atmospheric-pressure oxygen radical source, using fluorescent confocal-laser microscopy and transmission electron microscopy (TEM). The results suggest that neutral oxygen species, particularly ground-state atomic oxygen [O(3Pj)], which is an effective species for inactivating P. digitatum spores, inhibit the function of the cell membrane of spores without causing major superficial morphological changes at a low O(3Pj) dose of ˜2.1 × 1019 cm-2 under an O(3Pj) flux of 2.3 × 1017 cm-2 s-1, following the oxidation of intracellular organelles up to an O(3Pj) dose of ˜1.0 × 1020 cm-2. Finally, intracellular nanostructures are degraded by excess oxygen radicals over an O(3Pj) dose of ˜1.0 × 1020 cm-2.

Endogenous ROS levels are increased in replicative senescence in human bone marrow mesenchymal stromal cells.

PubMed

Jeong, Sin-Gu; Cho, Goang-Won

2015-05-15

Cellular senescence is characterized by functional decline induced by cumulative damage to DNA, proteins, lipids, and carbohydrates. Previous studies have reported that replicative senescence is caused by excessive amounts of reactive oxygen species (ROS) produced as a result of aerobic energy metabolism. In this study, we established human bone marrow mesenchymal stromal cells (hBM-MSCs) in replicative senescence after culture over a long term to investigate the relationship between ROS levels and stem cell potential and to determine whether differentiation potential can be restored by antioxidant treatment. Intracellular ROS levels were increased in hBM-MSCs; this was accompanied by a decrease in the expression of the antioxidant enzymes catalase and superoxide dismutase (SOD)1 and 2 and of phosphorylated forkhead box O1 (p-FOXO1) as well as an increase in the expression of p53 and p16, along with a reduction in differentiation potential. When the antioxidant ascorbic acid was used to eliminate excess ROS, the levels of antioxidant enzymes (catalase, SOD1 and 2, p-FOXO1, and p53) were partly restored. Moreover, differentiation into adipocytes and osteocytes was higher in hBM-MSCs treated with ascorbic acid than in the untreated control cells. These results suggest that the decline in differentiation potential caused by increased endogenous ROS production during in vitro expansion can be reversed by treatment with antioxidants such as ascorbic acid. Copyright © 2015 Elsevier Inc. All rights reserved.

Mechanisms for regulating oxygen toxicity in phytophagous insects.

PubMed

Ahmad, S; Pardini, R S

1990-01-01

The antioxidant enzymatic defense of insects for the regulation of oxygen toxicity was investigated. Insect species examined were lepidopterous larvae of the cabbage looper (Trichoplusia ni), southern armyworm (Spodoptera eridania), and black swallowtail (Papilio polyxenes). These phytophagous species are subject to both endogenous and exogenous sources of oxidative stress from toxic oxygen radicals, hydrogen peroxide (H2O2) and lipid peroxides (LOOH). In general, the constitutive levels of the enzymes superoxide dismutase (SOD), catalase (CAT), glutathione transferase (GT), and its peroxidase activity (GTpx), and glutathione reductase (GR), correlate well with natural feeding habits of these insects and their relative susceptibility to prooxidant plant allelochemicals, quercetin (a flavonoid), and xanthotoxin (a photoactive furanocoumarin). Induction of SOD activity which rapidly destroys superoxide radicals, appears to be the main response to dietary prooxidant exposure. A unique observation includes high constitutive activity of CAT and a broader subcellular distribution in all three insects than observed in most mammalian species. These attributes of CAT appear to be important in the prevention of excessive accumulation of cytotoxic H2O2. Unlike mammalian species, insects possess very low levels of a GPOX-like activity toward H2O2. Irrefutable proof that this activity is due to a selenium-dependent GPOX found in mammals, is lacking at this time. However, the activity of selenium-independent GTpx is unusually high in insects, suggesting that GTpx and not GPOX plays a prominent role in scavenging deleterious LOOHs. The GSSG generated from the GPOX and GTpx reactions may be reduced to GSH by GR activity. A key role of SOD in protecting insects from prooxidant toxicity was evident when its inhibition resulted in enhanced toxicity towards prooxidants. The role of antioxidant compounds in protecting these insects from toxic forms of oxygen has not been explored in depth. A major finding, however, is that these insects are lutein accumulators. Lutein is a dihydroxy (diol) derivative of beta-carotene, and it is a good quencher of activated forms of oxygen and free radicals. Levels of lutein are highest in P. polyxenes which specializes in feeding on prooxidant-containing plants.

Measurement of the 17O-excess (Δ17O) of tropospheric ozone using a nitrite-coated filter.

PubMed

Vicars, William C; Bhattacharya, S K; Erbland, Joseph; Savarino, Joël

2012-05-30

The (17)O-excess (Δ(17)O) of tropospheric ozone (O(3)) serves as a useful marker in studies of atmospheric oxidation pathways; however, due to the complexity and expense of currently available analytical techniques, no systematic sampling campaign has yet been undertaken and natural variations in Δ(17)O(O(3)) are therefore not well constrained. The nitrite-coated filter method is a new technique for O(3) isotope analysis that employs the aqueous phase NO(2)(-) + O(3) → NO(3)(-) + O(2) reaction to obtain quantitative information on O(3) via the oxygen atom transfer to nitrate (NO(3)(-)). The triple-oxygen isotope analysis of the NO(3)(-) produced during this reaction, achieved in this study using the bacterial denitrifier method followed by isotope-ratio mass spectrometry (IRMS), directly yields the Δ(17)O value transferred from O(3). This isotope transfer process was investigated in a series of vacuum-line experiments, which were conducted by exposing coated filters to O(3) of various known Δ(17)O values and then determining the isotopic composition of the NO(3)(-) produced on the filter. The isotope transfer experiments revealed a strong linear correlation between the Δ(17)O of the O(3) produced and that of the oxygen atom transferred to NO(3)(-), with a slope of 1.55 for samples with bulk Δ(17)O(O(3)) values in the atmospheric range (20-40‰). This finding is in agreement with theoretical postulates that place the (17) O-excess on only the terminal oxygen atoms of ozone. Ambient measurements yield average Δ(17)O(O(3))(bulk) values in agreement with previous studies (22.9 ± 1.9‰). The nitrite-coated filter technique is a sufficiently robust, field-deployable method for the determination of the triple-oxygen isotopic composition of tropospheric O(3). Further ambient measurements will undoubtedly lead to an improved quantitative view of natural Δ(17)O(O(3)) variation and transfer in the atmosphere. Copyright © 2012 John Wiley & Sons, Ltd.

Hypoxia promotes liver-stage malaria infection in primary human hepatocytes in vitro.

PubMed

Ng, Shengyong; March, Sandra; Galstian, Ani; Hanson, Kirsten; Carvalho, Tânia; Mota, Maria M; Bhatia, Sangeeta N

2014-02-01

Homeostasis of mammalian cell function strictly depends on balancing oxygen exposure to maintain energy metabolism without producing excessive reactive oxygen species. In vivo, cells in different tissues are exposed to a wide range of oxygen concentrations, and yet in vitro models almost exclusively expose cultured cells to higher, atmospheric oxygen levels. Existing models of liver-stage malaria that utilize primary human hepatocytes typically exhibit low in vitro infection efficiencies, possibly due to missing microenvironmental support signals. One cue that could influence the infection capacity of cultured human hepatocytes is the dissolved oxygen concentration. We developed a microscale human liver platform comprised of precisely patterned primary human hepatocytes and nonparenchymal cells to model liver-stage malaria, but the oxygen concentrations are typically higher in the in vitro liver platform than anywhere along the hepatic sinusoid. Indeed, we observed that liver-stage Plasmodium parasite development in vivo correlates with hepatic sinusoidal oxygen gradients. Therefore, we hypothesized that in vitro liver-stage malaria infection efficiencies might improve under hypoxia. Using the infection of micropatterned co-cultures with Plasmodium berghei, Plasmodium yoelii or Plasmodium falciparum as a model, we observed that ambient hypoxia resulted in increased survival of exo-erythrocytic forms (EEFs) in hepatocytes and improved parasite development in a subset of surviving EEFs, based on EEF size. Further, the effective cell surface oxygen tensions (pO2) experienced by the hepatocytes, as predicted by a mathematical model, were systematically perturbed by varying culture parameters such as hepatocyte density and height of the medium, uncovering an optimal cell surface pO2 to maximize the number of mature EEFs. Initial mechanistic experiments revealed that treatment of primary human hepatocytes with the hypoxia mimetic, cobalt(II) chloride, as well as a HIF-1α activator, dimethyloxalylglycine, also enhance P. berghei infection, suggesting that the effect of hypoxia on infection is mediated in part by host-dependent HIF-1α mechanisms.

Materials screening chamber for testing materials resistance to atomic oxygen

NASA Technical Reports Server (NTRS)

Pippin, H. G.; Carruth, Ralph

1989-01-01

A unique test chamber for exposing material to a known flux of oxygen atoms is described. The capabilities and operating parameters of the apparatus include production of an oxygen atom flux in excess of 5 x 10 to the 16th atoms/sq cm-sec, controlled heating of the sample specimen, RF circuitry to contain the plasma within a small volume, and long exposure times. Flux measurement capabilities include a calorimetric probe and a light titration system. Accuracy and limitations of these techniques are discussed. An extension to the main chamber to allow simultaneous ultraviolet and atomic oxygen exposure is discussed. The oxygen atoms produced are at thermal energies. Sample specimens are maintained at any selected temperature between ambient and 200 C, to within + or - 2 C. A representative example of measurements made using the chamber is presented.

Proteomic analysis of a model unicellular green alga, Chlamydomonas reinhardtii, during short-term exposure to irradiance stress reveals significant down regulation of several heat-shock proteins.

PubMed

Mahong, Bancha; Roytrakul, Suttiruk; Phaonaklop, Narumon; Wongratana, Janewit; Yokthongwattana, Kittisak

2012-03-01

Oxygenic photosynthetic organisms often suffer from excessive irradiance, which cause harmful effects to the chloroplast proteins and lipids. Photoprotection and the photosystem II repair processes are the mechanisms that plants deploy to counteract the drastic effects from irradiance stress. Although the protective and repair mechanisms seemed to be similar in most plants, many species do confer different level of tolerance toward high light. Such diversity may originate from differences at the molecular level, i.e., perception of the light stress, signal transduction and expression of stress responsive genes. Comprehensive analysis of overall changes in the total pool of proteins in an organism can be performed using a proteomic approach. In this study, we employed 2-DE/LC-MS/MS-based comparative proteomic approach to analyze total proteins of the light sensitive model unicellular green alga Chlamydomonas reinhardtii in response to excessive irradiance. Results showed that among all the differentially expressed proteins, several heat-shock proteins and molecular chaperones were surprisingly down-regulated after 3-6 h of high light exposure. Discussions were made on the possible involvement of such down regulation and the light sensitive nature of this model alga.

Achieving the Balance between ROS and Antioxidants: When to Use the Synthetic Antioxidants

PubMed Central

Poljsak, Borut; Šuput, Dušan; Milisav, Irina

2013-01-01

Free radical damage is linked to formation of many degenerative diseases, including cancer, cardiovascular disease, cataracts, and aging. Excessive reactive oxygen species (ROS) formation can induce oxidative stress, leading to cell damage that can culminate in cell death. Therefore, cells have antioxidant networks to scavenge excessively produced ROS. The balance between the production and scavenging of ROS leads to homeostasis in general; however, the balance is somehow shifted towards the formation of free radicals, which results in accumulated cell damage in time. Antioxidants can attenuate the damaging effects of ROS in vitro and delay many events that contribute to cellular aging. The use of multivitamin/mineral supplements (MVMs) has grown rapidly over the past decades. Some recent studies demonstrated no effect of antioxidant therapy; sometimes the intake of antioxidants even increased mortality. Oxidative stress is damaging and beneficial for the organism, as some ROS are signaling molecules in cellular signaling pathways. Lowering the levels of oxidative stress by antioxidant supplements is not beneficial in such cases. The balance between ROS and antioxidants is optimal, as both extremes, oxidative and antioxidative stress, are damaging. Therefore, there is a need for accurate determination of individual's oxidative stress levels before prescribing the supplement antioxidants. PMID:23738047

Toxic AGE (TAGE) Theory for the Pathophysiology of the Onset/Progression of NAFLD and ALD

PubMed Central

Takeuchi, Masayoshi; Takino, Jun-ichi; Sakasai-Sakai, Akiko; Takata, Takanobu; Tsutsumi, Mikihiro

2017-01-01

Non-alcoholic fatty liver disease (NAFLD) and alcoholic liver disease (ALD) are among the most common causes of chronic liver diseases in the westernized world. NAFLD and ALD are frequently accompanied by extrahepatic complications, including hepatocellular carcinoma and cardiovascular diseases, which have a negative impact on patient survival. The chronic ingestion of an excessive daily diet containing sugar/high-fructose corn syrup increases the level of the fructose/glucose metabolite, glyceraldehyde (GA), while the chronic consumption of an excessive number of alcoholic beverages increases the level of the alcohol metabolite, acetaldehyde (AA) in the liver. GA and AA are known to react non-enzymatically with the ε- or α-amino groups of proteins, thereby generating advanced glycation end-products (AGEs, GA-AGEs, and AA-AGEs, respectively) in vivo. The interaction between GA-AGEs and the receptor for AGEs (RAGE) alters intracellular signaling, gene expression, and the release of pro-inflammatory molecules and also elicits the production of reactive oxygen species by human hepatocytes and hepatic stellate cells, all of which may contribute to the pathological changes associated with chronic liver diseases. We herein discuss the pathophysiological roles of GA-AGEs and AA-AGEs (toxic AGEs, TAGE) and a related novel theory for preventing the onset/progression of NAFLD and ALD. PMID:28632197

Inhibition of autophagy and glycolysis by nitric oxide during hypoxia-reoxygenation impairs cellular bioenergetics and promotes cell death in primary neurons.

PubMed

Benavides, Gloria A; Liang, Qiuli; Dodson, Matthew; Darley-Usmar, Victor; Zhang, Jianhua

2013-12-01

Excessive nitric oxide (NO) production is known to damage mitochondrial proteins and the autophagy repair pathway and so can potentially contribute to neurotoxicity. Accordingly, we hypothesized that protection against protein damage from reactive oxygen and nitrogen species under conditions of low oxygen by the autophagy pathway in neurons would be impaired by NO and enhance bioenergetic dysfunction. Rat primary cortical neurons had the same basal cellular respiration in hypoxia as in normoxia, whereas NO-exposed cells exhibited a gradual decrease in mitochondrial respiration in hypoxia. Upon reoxygenation, the respiration in NO-treated cells did not recover to prehypoxic levels. Hypoxia-reoxygenation in the presence of NO was associated with inhibition of autophagy, and the inability to recover during reoxygenation was exacerbated by an inhibitor of autophagy, 3-methyladenine. The effects of hypoxia could be recapitulated by inhibiting glycolytic flux under normoxic conditions. Under both normoxic and hypoxic conditions NO exposure induced immediate stimulation of glycolysis, but prolonged NO exposure, associated with irreversible inhibition of mitochondrial respiration in hypoxia, inhibited glycolysis. Importantly, we found that NO inhibited basal respiration under normoxic conditions only when glucose was absent from the medium or glycolysis was inhibited by 2-deoxy-d-glucose, revealing a novel NO-dependent mechanism for the inhibition of mitochondrial respiration that is modulated by glycolysis. Taken together these data suggest an oxygen-dependent interaction between mitochondrial respiration, glycolysis, and autophagy in protecting neuronal cells exposed to NO. Importantly, they indicate that mitochondrial dysfunction is intimately linked to a failure of glycolytic flux induced by exposure to NO. In addition, these studies provide new insights into the understanding of how autophagy and NO may play interactive roles in neuroinflammation-induced cellular damage, which is pertinent to our understanding of the pathology of neurodegenerative diseases in which excessive NO is generated. © 2013 Elsevier Inc. All rights reserved.

Dynamics and stoichiometry of nutrients and phytoplankton in waters influenced by the oxygen minimum zone in the eastern tropical Pacific

NASA Astrophysics Data System (ADS)

Franz, Jasmin; Krahmann, Gerd; Lavik, Gaute; Grasse, Patricia; Dittmar, Thorsten; Riebesell, Ulf

2012-04-01

The tropical South East Pacific is characterized by strong coastal upwelling on the narrow continental shelf and an intense oxygen minimum zone (OMZ) in the intermediate water layer. These hydrographic properties are responsible for a permanent supply of intermediate water masses to the surface rich in nutrients and with a remarkably low inorganic N:P stoichiometry. To investigate the impact of OMZ-influenced upwelling waters on phytoplankton growth, elemental and taxonomical composition we measured hydrographic and biogeochemical parameters along an east-west transect at 10°S in the tropical South East Pacific, stretching from the upwelling region above the narrow continental shelf to the well-stratified oceanic section of the eastern boundary regime. New production in the area of coastal upwelling was driven by large-sized phytoplankton (e.g. diatoms) with generally low N:P ratios (<16:1). While nitrate and phosphate concentrations were at levels not limiting phytoplankton growth along the entire transect, silicate depletion prohibited diatom growth further off-shore. A deep chlorophyll a maximum consisting of pico-/nano- (Synechococcus, flagellates) and microphytoplankton occurred within a pronounced thermocline in subsurface waters above the shelf break and showed intermediate N:P ratios close to Redfield proportions. High PON:POP (>20:1) ratios were observed in the stratified open ocean section of the transect, coinciding with the abundance of two strains of the pico-cyanobacterium Prochlorococcus; a high-light adapted strain in the surface layer and a low-light adapted strain occurring along the oxic-anoxic transition zone below the thermocline. Excess phosphate present along the entire transect did not appear to stimulate growth of nitrogen-fixing phytoplankton, as pigment fingerprinting did not indicate the presence of diazotrophic cyanobacteria at any of our sampling stations. Instead, a large fraction of the excess phosphate generated within the oxygen minimum zone was consumed by non-Redfield production of large phytoplankton in shelf surface waters.

Glutathione peroxidase level in patients with Helicobacter pylori-associated gastritis

NASA Astrophysics Data System (ADS)

Tala, Z. Z.; Siregar, G. A.; Siregar, G. P.

2018-03-01

Helicobacter pylori (H. pylori) associated with the generation of reactive oxygen species (ROS), with leads to oxidative stress in the gastric mucosa. GPX is one of human antioxidative defense system allows the elimination of excess ROS. A cross-sectional study was in 80 consecutive gastritis patients who came to the endoscopic unit of Adam Malik General Hospital and PermataBunda Hospital in Medan, Indonesia, from May–September 2017, to determine the difference of GPX serum level between positive and negative infected H. pylori. the diagnosis of gastritis used Histopathology. Rapid urease test for diagnosis of H. pylori infection. Serum samples were obtained to determined circulating GPX. It used Univariate and bivariate analysis (Mann Whitney U test). There were 50 patients (62.5%) infected with H. pylori. GPX levels in patients with positive H. pylori gastritis were lower than those of negative H. pylori but did not differ significantly. In conclusion, there were no significant differences in GPX level between positive and negative infected H. pylori patients.

Hyperglycaemia does not affect antigen-specific activation and cytolytic killing by CD8+ T cells in vivo.

PubMed

Recino, Asha; Barkan, Kerry; Wong, F Susan; Ladds, Graham; Cooke, Anne; Wallberg, Maja

2017-08-31

Metabolism is of central importance for T cell survival and differentiation. It is well known that T cells cannot function in the absence of glucose, but it is less clear how they respond to excessive levels of glucose. In the present study, we investigated how increasing levels of glucose affect T-cell-mediated immune responses. We examined the effects of increased levels of glucose on CD8 + T-cell behaviour in vitro by assessing activation and cytokine production, as well as oxygen consumption rate (OCR), extracellular acidification rate (ECAR) and intracellular signalling. In addition, we assessed in vivo proliferation, cytokine production and cytolytic activity of cells in chemically induced diabetic C57BL/6 mice. Elevated levels of glucose in in vitro cultures had modest effects on proliferation and cytokine production, while in vivo hyperglycaemia had no effect on CD8 + T-cell proliferation, interferon γ (IFNγ) production or cytolytic killing. © 2017 The Author(s).

Memory CD8+ T cells are sufficient to alleviate impaired host resistance to influenza A virus infection caused by neonatal oxygen supplementation.

PubMed

Giannandrea, Matthew; Yee, Min; O'Reilly, Michael A; Lawrence, B Paige

2012-09-01

Supplemental oxygen administered to preterm infants is an important clinical intervention, but it is associated with life-long changes in lung development and increased sensitivity to respiratory viral infections. The precise immunological changes caused by neonatal oxygen treatment remain poorly understood. We previously reported that adult mice exposed to supplemental oxygen as neonates display persistent pulmonary inflammation and enhanced mortality after a sublethal influenza A virus infection. These changes suggest that neonatal hyperoxia impairs the cytotoxic CD8(+) T cell response required to clear the virus. In this study, we show that although host resistance to several different strains of influenza A virus is reduced by neonatal hyperoxia, this treatment does not impair viral clearance, nor does it alter the magnitude of the virus-specific CD8(+) T cell response to primary infection. Moreover, memory T cells are sufficient to ameliorate the increased morbidity and mortality and alleviate the excessive lung damage observed in mice exposed to high oxygen levels as neonates, and we attribute this sufficiency principally to virus-specific memory CD8(+) T cells. Thus, we show that neonatal hyperoxia reduces host resistance to influenza virus infection without diminishing the function of cytotoxic T lymphocytes or the generation of virus-specific memory T cells and that CD8(+) memory T cells are sufficient to provide protection from negative consequences of this important life-saving intervention. Our findings suggest that vaccines that generate robust T cell memory may be efficacious at reducing the increased sensitivity to respiratory viral infections in people born prematurely.

Phosphorus and groundwater: Establishing links between agricultural use and transport to streams

USGS Publications Warehouse

Domagalski, Joseph L.; Johnson, Henry

2012-01-01

Leaching of applied fertilizer and surface runoff of phosphorus from the soil can contribute to excess growth of algae in downstream water bodies, a condition known as eutrophication. Excessive amounts of algae in eutrophic water bodies can cause large daily changes in the amount of dissolved oxygen in the water because oxygen concentrations tend to be high during daylight hours as a result of photosynthetic activity but then decrease at night. Low concentrations of dissolved oxygen can stress or kill sensitive species living in the water. This study examined concentrations and movement of phosphorus in the soils and groundwater in five agricultural settings across the United States characterized by differences in soil geochemistry, climate, irrigation usage, and cropping systems to assess potential phosphorus movement in the soil and groundwater under common agricultural conditions. The study design included assessment of a variety of agricultural practices, especially cropping patterns and irrigation, so that the factors that contribute to phosphorus movement to groundwater, or sequestration of the phosphorus to soil could be compared and examined. This type of information could potentially be used to formulate best management practices to limit the transport of phosphorus from the agricultural fields.

Insulating ferromagnetic oxide films: the controlling role of oxygen vacancy ordering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Salafranca Laforga, Juan I; Salafranca, Juan; Biskup, Nevenko

2014-01-01

The origin of ferromagnetism in strained epitaxial LaCoO3 films has been a long-standing mystery. Here, we combine atomically resolved Z-contrast imaging, electron-energy-loss spectroscopy, and density-functional calculations to demonstrate that, in epitaxial LaCoO3 films, oxygen-vacancy superstructures release strain, control the film s electronic properties, and produce the observed ferromagnetism via the excess electrons in the Co d states. Although oxygen vacancies typically dope a material n-type, we find that ordered vacancies induce Peierls-like minigaps which, combined with strain relaxation, trigger a nonlinear rupture of the energy bands, resulting in insulating behavior.

Insulating Ferromagnetic LaCoO3-δ Films: A Phase Induced by Ordering of Oxygen Vacancies

NASA Astrophysics Data System (ADS)

Biškup, Neven; Salafranca, Juan; Mehta, Virat; Oxley, Mark P.; Suzuki, Yuri; Pennycook, Stephen J.; Pantelides, Sokrates T.; Varela, Maria

2014-02-01

The origin of ferromagnetism in strained epitaxial LaCoO3 films has been a long-standing mystery. Here, we combine atomically resolved Z-contrast imaging, electron-energy-loss spectroscopy, and density-functional calculations to demonstrate that, in epitaxial LaCoO3 films, oxygen-vacancy superstructures release strain, control the film's electronic properties, and produce the observed ferromagnetism via the excess electrons in the Co d states. Although oxygen vacancies typically dope a material n-type, we find that ordered vacancies induce Peierls-like minigaps which, combined with strain relaxation, trigger a nonlinear rupture of the energy bands, resulting in insulating behavior.

Nonoxidative Glucose Consumption during Focal Physiologic Neural Activity

NASA Astrophysics Data System (ADS)

Fox, Peter T.; Raichle, Marcus E.; Mintun, Mark A.; Dence, Carmen

1988-07-01

Brain glucose uptake, oxygen metabolism, and blood flow in humans were measured with positron emission tomography, and a resting-state molar ratio of oxygen to glucose consumption of 4.1:1 was obtained. Physiological neural activity, however, increased glucose uptake and blood flow much more (51 and 50 percent, respectively) than oxygen consumption (5 percent) and produced a molar ratio for the increases of 0.4:1. Transient increases in neural activity cause a tissue uptake of glucose in excess of that consumed by oxidative metabolism, acutely consume much less energy than previously believed, and regulate local blood flow for purposes other than oxidative metabolism.

Cascade heat recovery with coproduct gas production

DOEpatents

Brown, W.R.; Cassano, A.A.; Dunbobbin, B.R.; Rao, P.; Erickson, D.C.

1986-10-14

A process for the integration of a chemical absorption separation of oxygen and nitrogen from air with a combustion process is set forth wherein excess temperature availability from the combustion process is more effectively utilized to desorb oxygen product from the absorbent and then the sensible heat and absorption reaction heat is further utilized to produce a high temperature process stream. The oxygen may be utilized to enrich the combustion process wherein the high temperature heat for desorption is conducted in a heat exchange preferably performed with a pressure differential of less than 10 atmospheres which provides considerable flexibility in the heat exchange. 4 figs.

Methane excess production in oxygen-rich polar water and a model of cellular conditions for this paradox

NASA Astrophysics Data System (ADS)

Damm, E.; Thoms, S.; Beszczynska-Möller, A.; Nöthig, E. M.; Kattner, G.

2015-09-01

Summer sea ice cover in the Arctic Ocean has undergone a reduction in the last decade exposing the sea surface to unforeseen environmental changes. Melting sea ice increases water stratification and induces nutrient limitation, which is also known to play a crucial role in methane formation in oxygenated surface water. We report on an excess of methane in the marginal ice zone in the western Fram Strait. Our study is based on measurements of oxygen, methane, DMSP, nitrate and phosphate concentrations as well as on phytoplankton composition and light transmission, conducted along the 79°N oceanographic transect, in the western part of the Fram Strait and in Northeast Water Polynya region off Greenland. Between the eastern Fram Strait, where Atlantic water enters from the south and the western Fram Strait, where Polar water enters from the north, different nutrient limitations occurred and consequently different bloom conditions were established. Ongoing sea ice melting enhances the environmental differences between both water masses and initiates regenerated production in the western Fram Strait. We show that in this region methane is in situ produced while DMSP (dimethylsulfoniopropionate) released from sea ice may serve as a precursor for the methane formation. The methane production occured despite high oxygen concentrations in this water masses. As the metabolic activity (respiration) of unicellular organisms explains the presence of anaerobic conditions in the cellular environment we present a theoretical model which explains the maintenance of anaerobic conditions for methane formation inside bacterial cells, despite enhanced oxygen concentrations in the environment.

Metabolic fate of glucose and candidate signaling and excess-fuel detoxification pathways in pancreatic β-cells.

PubMed

Mugabo, Yves; Zhao, Shangang; Lamontagne, Julien; Al-Mass, Anfal; Peyot, Marie-Line; Corkey, Barbara E; Joly, Erik; Madiraju, S R Murthy; Prentki, Marc

2017-05-05

Glucose metabolism promotes insulin secretion in β-cells via metabolic coupling factors that are incompletely defined. Moreover, chronically elevated glucose causes β-cell dysfunction, but little is known about how cells handle excess fuels to avoid toxicity. Here we sought to determine which among the candidate pathways and coupling factors best correlates with glucose-stimulated insulin secretion (GSIS), define the fate of glucose in the β-cell, and identify pathways possibly involved in excess-fuel detoxification. We exposed isolated rat islets for 1 h to increasing glucose concentrations and measured various pathways and metabolites. Glucose oxidation, oxygen consumption, and ATP production correlated well with GSIS and saturated at 16 mm glucose. However, glucose utilization, glycerol release, triglyceride and glycogen contents, free fatty acid (FFA) content and release, and cholesterol and cholesterol esters increased linearly up to 25 mm glucose. Besides being oxidized, glucose was mainly metabolized via glycerol production and release and lipid synthesis (particularly FFA, triglycerides, and cholesterol), whereas glycogen production was comparatively low. Using targeted metabolomics in INS-1(832/13) cells, we found that several metabolites correlated well with GSIS, in particular some Krebs cycle intermediates, malonyl-CoA, and lower ADP levels. Glucose dose-dependently increased the dihydroxyacetone phosphate/glycerol 3-phosphate ratio in INS-1(832/13) cells, indicating a more oxidized state of NAD in the cytosol upon glucose stimulation. Overall, the data support a role for accelerated oxidative mitochondrial metabolism, anaplerosis, and malonyl-CoA/lipid signaling in β-cell metabolic signaling and suggest that a decrease in ADP levels is important in GSIS. The results also suggest that excess-fuel detoxification pathways in β-cells possibly comprise glycerol and FFA formation and release extracellularly and the diversion of glucose carbons to triglycerides and cholesterol esters. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Why do premature newborn infants display elevated blood adenosine levels?

PubMed

Panfoli, Isabella; Cassanello, Michela; Bruschettini, Matteo; Colella, Marina; Cerone, Roberto; Ravera, Silvia; Calzia, Daniela; Candiano, Giovanni; Ramenghi, Luca

2016-05-01

Our preliminary data show high levels of adenosine in the blood of very low birth weight (VLBW) infants, positively correlating to their prematurity (i.e. body weight class). This prompted us to look for a mechanism promoting such impressive adenosine increase. We hypothesized a correlation with oxygen challenge. In fact, it is recognized that either oxygen lack or its excess contribute to the pathogenesis of the injuries of prematurity, such as retinopathy (ROP) and periventricular white matter lesions (PWMI). The optimal concentration of oxygen for resuscitation of VLBW infants is currently under revision. We propose that the elevated adenosine blood concentrations of VLBW infants recognizes two sources. The first could be its activity-dependent release from unmyelinated brain axons. Adenosine in this respect would be an end-product of the hypometabolic VLBW newborn unmyelinated axon intensely firing in response to the environmental stimuli consequent to premature birth. Adenosine would be eventually found in the blood due to blood-brain barrier immaturity. In fact, adenosine is the primary activity-dependent signal promoting differentiation of premyelinating oligodendrocyte progenitor cells (OPC) into myelinating cells in the Central Nervous System, while inhibiting their proliferation and inhibiting synaptic function. The second, would be the ecto-cellular ATP synthesized by the endothelial cell plasmalemma exposed to ambient oxygen concentrations due to premature breathing, especially in lung. ATP would be rapidly transformed into adenosine by the ectonucleotidase activities such as NTPDase I (CD39), and NT5E (CD73). An ectopic extra-mitochondrial aerobic ATP synthetic ability was reported in many cell plasma-membranes, among which endothelial cells. The potential implications of the cited hypotheses for the neonatology area would be great. The amount of oxygen administration for reviving of newborns would find a molecular basis for its assessment. VLBW infants may be regarded as those in which premature exposure to ambient oxygen concentrations and oxidative stress causes a premature functioning of the extra-mitochondrial oxidative phosphorylation primarily in axons and endothelium. Adenosine may become a biomarker of prematurity risk, whose implications further studies may assess. Copyright © 2016 Elsevier Ltd. All rights reserved.

Detrimental effects of adenosine signaling in sickle cell disease

PubMed Central

Zhang, Yujin; Dai, Yingbo; Wen, Jiaming; Zhang, Weiru; Grenz, Almut; Sun, Hong; Tao, Lijian; Lu, Guangxiu; Alexander, Danny C; Milburn, Michael V; Carter-Dawson, Louvenia; Lewis, Dorothy E; Zhang, Wenzheng; Eltzschig, Holger K; Kellems, Rodney E; Blackburn, Michael R; Juneja, Harinder S; Xia, Yang

2016-01-01

Hypoxia can act as an initial trigger to induce erythrocyte sickling and eventual end organ damage in sickle cell disease (SCD). Many factors and metabolites are altered in response to hypoxia and may contribute to the pathogenesis of the disease. Using metabolomic profiling, we found that the steady-state concentration of adenosine in the blood was elevated in a transgenic mouse model of SCD. Adenosine concentrations were similarly elevated in the blood of humans with SCD. Increased adenosine levels promoted sickling, hemolysis and damage to multiple tissues in SCD transgenic mice and promoted sickling of human erythrocytes. Using biochemical, genetic and pharmacological approaches, we showed that adenosine A2B receptor (A2BR)-mediated induction of 2,3-diphosphoglycerate, an erythrocyte-specific metabolite that decreases the oxygen binding affinity of hemoglobin, underlies the induction of erythrocyte sickling by excess adenosine both in cultured human red blood cells and in SCD transgenic mice. Thus, excessive adenosine signaling through the A2BR has a pathological role in SCD. These findings may provide new therapeutic possibilities for this disease. PMID:21170046

Protective role of integrin-linked kinase against oxidative stress and in maintenance of genomic integrity

PubMed Central

Im, Michelle; Dagnino, Lina

2018-01-01

The balance between the production of reactive oxygen species and activation of antioxidant pathways is essential to maintain a normal redox state in all tissues. Oxidative stress caused by excessive oxidant species generation can cause damage to DNA and other macromolecules, affecting cell function and viability. Here we show that integrin-linked kinase (ILK) plays a key role in eliciting a protective response to oxidative damage in epidermal cells. Inactivation of the Ilk gene causes elevated levels of intracellular oxidant species (IOS) and DNA damage in the absence of exogenous oxidative insults. In ILK-deficient cells, excessive IOS production can be prevented through inhibition of NADPH oxidase activity, with a concomitant reduction in DNA damage. Additionally, ILK is necessary for DNA repair processes following UVB-induced damage, as ILK-deficient cells show a significantly impaired ability to remove cyclobutane pyrimidine dimers following irradiation. Thus, ILK is essential to maintain cellular redox balance and, in its absence, epidermal cells become more susceptible to oxidative damage through mechanisms that involve IOS production by NADPH oxidase activity. PMID:29568383

Protective role of integrin-linked kinase against oxidative stress and in maintenance of genomic integrity.

PubMed

Im, Michelle; Dagnino, Lina

2018-03-02

The balance between the production of reactive oxygen species and activation of antioxidant pathways is essential to maintain a normal redox state in all tissues. Oxidative stress caused by excessive oxidant species generation can cause damage to DNA and other macromolecules, affecting cell function and viability. Here we show that integrin-linked kinase (ILK) plays a key role in eliciting a protective response to oxidative damage in epidermal cells. Inactivation of the Ilk gene causes elevated levels of intracellular oxidant species (IOS) and DNA damage in the absence of exogenous oxidative insults. In ILK-deficient cells, excessive IOS production can be prevented through inhibition of NADPH oxidase activity, with a concomitant reduction in DNA damage. Additionally, ILK is necessary for DNA repair processes following UVB-induced damage, as ILK-deficient cells show a significantly impaired ability to remove cyclobutane pyrimidine dimers following irradiation. Thus, ILK is essential to maintain cellular redox balance and, in its absence, epidermal cells become more susceptible to oxidative damage through mechanisms that involve IOS production by NADPH oxidase activity.

Detrimental effects of adenosine signaling in sickle cell disease.

PubMed

Zhang, Yujin; Dai, Yingbo; Wen, Jiaming; Zhang, Weiru; Grenz, Almut; Sun, Hong; Tao, Lijian; Lu, Guangxiu; Alexander, Danny C; Milburn, Michael V; Carter-Dawson, Louvenia; Lewis, Dorothy E; Zhang, Wenzheng; Eltzschig, Holger K; Kellems, Rodney E; Blackburn, Michael R; Juneja, Harinder S; Xia, Yang

2011-01-01

Hypoxia can act as an initial trigger to induce erythrocyte sickling and eventual end organ damage in sickle cell disease (SCD). Many factors and metabolites are altered in response to hypoxia and may contribute to the pathogenesis of the disease. Using metabolomic profiling, we found that the steady-state concentration of adenosine in the blood was elevated in a transgenic mouse model of SCD. Adenosine concentrations were similarly elevated in the blood of humans with SCD. Increased adenosine levels promoted sickling, hemolysis and damage to multiple tissues in SCD transgenic mice and promoted sickling of human erythrocytes. Using biochemical, genetic and pharmacological approaches, we showed that adenosine A(2B) receptor (A(2B)R)-mediated induction of 2,3-diphosphoglycerate, an erythrocyte-specific metabolite that decreases the oxygen binding affinity of hemoglobin, underlies the induction of erythrocyte sickling by excess adenosine both in cultured human red blood cells and in SCD transgenic mice. Thus, excessive adenosine signaling through the A(2B)R has a pathological role in SCD. These findings may provide new therapeutic possibilities for this disease.

The effect of dissolved oxygen on the susceptibility of blood.

PubMed

Berman, Avery J L; Ma, Yuhan; Hoge, Richard D; Pike, G Bruce

2016-01-01

It has been predicted that, during hyperoxia, excess O2 dissolved in arterial blood will significantly alter the blood's magnetic susceptibility. This would confound the interpretation of the hyperoxia-induced blood oxygenation level-dependent signal as arising solely from changes in deoxyhemoglobin. This study, therefore, aimed to determine how dissolved O2 affects the susceptibility of blood. We present a comprehensive model for the effect of dissolved O2 on the susceptibility of blood and compare it with another recently published model, referred to here as the ideal gas model (IGM). For validation, distilled water and samples of bovine plasma were oxygenated over a range of hyperoxic O2 concentrations and their susceptibilities were determined using multiecho gradient echo phase imaging. In distilled water and plasma, the measured changes in susceptibility were very linear, with identical slopes of 0.062 ppb/mm Hg of O2. This change was dramatically less than previously predicted using the IGM and was close to that predicted by our model. The primary source of error in the IGM is the overestimation of the volume fraction occupied by dissolved O2. Under most physiological conditions, the susceptibility of dissolved O2 can be disregarded in MRI studies employing hyperoxia. © 2015 Wiley Periodicals, Inc.

Acute collective gas poisoning at work in a manure storage tank.

PubMed

Żaba, Czesław; Marcinkowski, Jerzy T; Wojtyła, Andrzej; Tężyk, Artur; Tobolski, Jarosław; Zaba, Zbigniew

2011-01-01

Cases of deaths in manure or septic tanks are rare in legal-medical practice, more frequently as unfortunate occupational accidents. Poisoning with toxic gases, especially with hydrogen sulfide, is reported as the cause of death, while the exhaustion of oxygen in the air is omitted with the simultaneous excess of carbon dioxide. In such cases, determination of the direct cause of death constitutes a big problem because post-mortem examination does not reveal the specific changes. A case of acute collective poisoning by gases in a manure storage tank is presented of 5 agricultural workers, 2 of whom died. While explaining the cause of poisoning and deaths, toxicological blood tests were performed in the victims of the accident, as well as gases inside the manure storage tank. The post-mortem examinations and toxicological blood tests performed did not allow determination of the direct cause of death. Toxicological tests of gases from inside the manure tank showed a very low concentration of oxygen, with a simultaneous very high concentration of carbon dioxide, and a considerable level of hydrogen sulfide. The cause of fainting of three and deaths of two workers was not the poisoning with hydrogen sulfide, but oxygen deficiency in the air of the tank.

Microstructure design for fast oxygen conduction

DOE PAGES

Aidhy, Dilpuneet S.; Weber, William J.

2015-11-11

Research from the last decade has shown that in designing fast oxygen conducting materials for electrochemical applications has largely shifted to microstructural features, in contrast to material-bulk. In particular, understanding oxygen energetics in heterointerface materials is currently at the forefront, where interfacial tensile strain is being considered as the key parameter in lowering oxygen migration barriers. Nanocrystalline materials with high densities of grain boundaries have also gathered interest that could possibly allow leverage over excess volume at grain boundaries, providing fast oxygen diffusion channels similar to those previously observed in metals. In addition, near-interface phase transformations and misfit dislocations aremore » other microstructural phenomenon/features that are being explored to provide faster diffusion. In this review, the current understanding on oxygen energetics, i.e., thermodynamics and kinetics, originating from these microstructural features is discussed. Moreover, our experimental observations, theoretical predictions and novel atomistic mechanisms relevant to oxygen transport are highlighted. In addition, the interaction of dopants with oxygen vacancies in the presence of these new microstructural features, and their future role in the design of future fast-ion conductors, is outlined.« less

High oxygen facilitates wound induction of suberin polyphenolics in kiwifruit.

PubMed

Wei, Xiaopeng; Mao, Linchun; Han, Xueyuan; Lu, Wenjing; Xie, Dandan; Ren, Xingchen; Zhao, Yuying

2018-04-01

Rapid wound healing would be critical for successful long-term storage of fruits and vegetables. However, there was no direct evidence for the requirement and efficiency of oxygen in the fruit wound-healing process. This study was conducted to investigate the role of oxygen in wound-induced suberization by analyzing melanin, suberin polyphenolics (SPPs) and related enzymes in half-cut kiwifruits exposed to 100%, 50%, 21% and 0% oxygen. By 3 days after wounding, the wound surface of kiwifruit in high (50 and 100%) oxygen appeared as a continuous layer of melanin and SPPs underneath, which effectively prevent excessive water vapor loss from the fruit halves. In contrast, melanin and SPPs deposition in the wound surface in 0% oxygen was significantly reduced, with high water vapor loss. Rapid decrease of soluble phenolic acids (caffeic, p-coumaric, ferulic acids) was coupled with the increase of bound ferulic acid (coniferyl diacetate) especially in high oxygen by 9 days after wounding. Meanwhile, high oxygen enhanced peroxidase, catalase, phenylalanine ammonia-lyase, and polyphenol oxidase activities. Oxygen is required for wound-induced melanin and SPPs formation, and high oxygen is effective in promoting wound suberization in postharvest kiwifruit. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Fate of oxygen losses from Typha domingensis (Typhaceae) and Cladium jamaicense (Cyperaceae) and consequences for root metabolism

USGS Publications Warehouse

Chabbi, A.; McKee, K.L.; Mendelssohn, I.A.

2000-01-01

The objective of this work was to determine whether radial oxygen loss (ROL) from roots of Typha domingensis and Cladium jamaicense creates an internal oxygen deficiency or, conversely, indicates adequate internal aeration and leakage of excess oxygen to the rhizosphere. Methylene blue in agar was used to quantify oxygen leakage. Typha's roots had a higher porosity than Cladium's and responded to flooding treatment by increasing cortical air space, particularly near the root tips. A greater oxygen release, which occurred along the subapical root axis, and an increase in rhizosphere redox potential (Eh) over time were associated with the well-developed aerenchyma system in Typha. Typha roots, regardless of oxygen release pattern, showed low or undetectable alcohol dehydrogenage (ADH) activity or ethanol concentrations, indicating that ROL did not cause internal deficiencies. Cladium roots also releases oxygen, but this loss primarily occurred at the root tips and was accompanied by increased root ADH activity and ethanol concentrations. These results support the hypothesis that oxygen release by Cladium is accompanied by internal deficiencies of oxygen sufficient to stimulate alcoholic fermentation and helps explain Cladium's lesser flood tolerance in comparison with Typha.

Effect of Staged Dissolved Oxygen Optimization on In-situ sludge Reduction and Enhanced Nutrient Removal in an A2MMBR-M System

NASA Astrophysics Data System (ADS)

Yang, Shan-Shan; Pang, Ji-Wei; Jin, Xiao-Man; Wu, Zhong-Yang; Yang, Xiao-Yin; Guo, Wan-Qian; Zhao, Zhi-Qing; Ren, Nan-Qi

2018-03-01

Redundant excess sludge production and considerable non-standard wastewater discharge from existing activated sludge processes are facing more and more challenges. The investigations on lower sludge production and higher sewage treatment efficiency are urgently needed. In this study, an anaerobic/anoxic/micro-aerobic/oxic-MBR combining a micro-aerobic starvation sludge holding tank (A2MMBR-M) system is developed. Batch tests on the optimization of the staged dissolved oxygen (DO) in the micro-aerobic, the first oxic, and the second oxic tanks were carried out by a 3-factor and 3-level Box-Behnken design (BBD). The optimal actual values of X1 , X2 , and X3 were DO1 of 0.3-0.5 mg/L, DO2 of 3.5-4.5 mg/L, and DO3 of 3-4 mg/L. After the optimization tests, continuous-flow experiments of anaerobic/anoxic/oxic (AAO) and A2MMBR-M systems were further conducted. Compared to AAO system, a 37.45% reduction in discharged excess sludge in A2MMBR-M system was achieved. The COD, TN, and TP removal efficiencies in A2MMBR-M system were respective 4.06%, 2.68%, and 4.04% higher than AAO system. The A2MMBR-M system is proved a promising wastewater treatment technology possessing enhanced in-situ sludge reduction and improved effluent quality. The staged optimized DO concentrations are the key controlling parameters for the realization of simultaneous in-situ sludge reduction and nutrient removal.

Application of an atomic oxygen beam facility to the investigation of shuttle glow chemistry

NASA Technical Reports Server (NTRS)

Arnold, G. S.; Peplinski, D. R.

1985-01-01

A facility for the investigation of the interactions of energetic atomic oxygen with solids is described. The facility is comprised of a four chambered, differentially pumped molecular beam apparatus which can be equipped with one of a variety of sources of atomic oxygen. The primary source is a dc arc heated supersonic nozzle source which produces a flux of atomic oxygen in excess of 10 to the 15th power sq cm/sec at the target, at a velocity of 3.5 km/sec. Results of applications of this facility to the study of the reactions of atomic oxygen with carbon and polyimide films are briefly reviewed and compared to data obtained on various flights of the space shuttle. A brief discussion of possible application of this facility to investigation of chemical reactions which might contribute to atmosphere induced vehicle glow is presented.

An effective device for gas-liquid oxygen removal in enclosed microalgae culture.

PubMed

Su, Zhenfeng; Kang, Ruijuan; Shi, Shaoyuan; Cong, Wei; Cai, Zhaoling

2010-01-01

A high-performance gas-liquid transmission device (HPTD) was described in this paper. To investigate the HPTD mass transfer characteristics, the overall volumetric mass transfer coefficients, K(A)(La,CO(2)) for the absorption of gaseous CO(2) and K(A)(La,O(2)) for the desorption of dissolved O(2) were determined, respectively, by titration and dissolved oxygen electrode. The mass transfer capability of carbon dioxide was compared with that of dissolved oxygen in the device, and the operating conditions were optimized to suit for the large-scale enclosed micro-algae cultivation. Based on the effectiveness evaluation of the HPTD applied in one enclosed flat plate Spirulina culture system, it was confirmed that the HPTD can satisfy the demand of the enclosed system for carbon supplement and excessive oxygen removal.

Use of anaerobic hydrolysis pretreatment to enhance ultrasonic disintegration of excess sludge.

PubMed

Li, Xianjin; Zhu, Tong; Shen, Yang; Chai, Tianyu; Xie, Yuanhua; You, Meiyan; Wang, Youzhao

2016-01-01

To improve the excess sludge disintegration efficiency, reduce the sludge disintegration cost, and increase sludge biodegradability, a combined pretreatment of anaerobic hydrolysis (AH) and ultrasonic treatment (UT) was proposed for excess sludge. Results showed that AH had an advantage in dissolving flocs, modifying sludge characteristics, and reducing the difficulty of sludge disintegration, whereas UT was advantageous in damaging cell walls, releasing intracellular substances, and decomposing macromolecular material. The combined AH-UT process was an efficient method for excess sludge pretreatment. The optimized solution involved AH for 3 days, followed by UT for 10 min. After treatment, chemical oxygen demand, protein, and peptidoglycan concentrations reached 3,949.5 mg O2/L, 752.5 mg/L and 619.1 mg/L, respectively. This work has great significance for further engineering applications, namely, reducing energy consumption, increasing the sludge disintegration rate, and improving the biochemical properties of sludge.

α-Syntrophin stabilizes catalase to reduce endogenous reactive oxygen species levels during myoblast differentiation.

PubMed

Moon, Jae Yun; Choi, Su Jin; Heo, Cheol Ho; Kim, Hwan Myung; Kim, Hye Sun

2017-07-01

α-Syntrophin is a component of the dystrophin-glycoprotein complex that interacts with various intracellular signaling proteins in muscle cells. The α-syntrophin knock-down C2 cell line (SNKD), established by infecting lentivirus particles with α-syntrophin shRNA, is characterized by a defect in terminal differentiation and increase in cell death. Since myoblast differentiation is accompanied by intensive mitochondrial biogenesis, the generation of intracellular reactive oxygen species (ROS) is also increased during myogenesis. Two-photon microscopy imaging showed that excessive intracellular ROS accumulated during the differentiation of SNKD cells as compared with control cells. The formation of 4-hydroxynonenal adduct, a byproduct of lipid peroxidation during oxidative stress, significantly increased in differentiated SNKD myotubes and was dramatically reduced by epigallocatechin-3-gallate, a well-known ROS scavenger. Among antioxidant enzymes, catalase was significantly decreased during differentiation of SNKD cells without changes at the mRNA level. Of interest was the finding that the degradation of catalase was rescued by MG132, a proteasome inhibitor, in the SNKD cells. This study demonstrates a novel function of α-syntrophin. This protein plays an important role in the regulation of oxidative stress from endogenously generated ROS during myoblast differentiation by modulating the protein stability of catalase. © 2017 Federation of European Biochemical Societies.

Development Status of the CECE Cryogenic Deep Throttling Demonstrator Engine

NASA Technical Reports Server (NTRS)

2008-01-01

As one of the first technology development programs awarded by NASA under the U.S. Space Exploration Policy (USSEP), the Pratt & Whitney Rocketdyne (PWR) Deep Throttling, Common Extensible Cryogenic Engine (CECE) program was selected by NASA in November 2004 to begin technology development and demonstration toward a deep throttling, cryogenic engine supporting ongoing trade studies for NASA's Lunar Lander descent stage. The CECE program leverages the maturity and previous investment of a flight-proven hydrogen/oxygen expander cycle engine, the PWR RLI0, to develop and demonstrate an unprecedented combination of reliability, safety, durability, throttlability, and restart capabilities in a high-energy, cryogenic engine. The testbed selected for the deep throttling demonstration phases of this program was a minimally modified RL10 engine, allowing for maximum current production engine commonality and extensibility with minimum program cost. Two series of demonstrator engine tests, the first in April-May 2006 and the second in March-April 2007, have demonstrated in excess of 10:1 throttling of the hydrogen/oxygen expander cycle engine. Both test series have explored a combustion instability ("chug") environment at low throttled power levels. These tests have provided an early demonstration of an enabling cryogenic propulsion concept with invaluable system-level technology data acquisition toward design and development risk mitigation for future CECE Demonstrator engine tests.

Cerebral oxygen delivery is reduced in newborns with congenital heart disease.

PubMed

Lim, Jessie Mei; Kingdom, Theodore; Saini, Brahmdeep; Chau, Vann; Post, Martin; Blaser, Susan; Macgowan, Christopher; Miller, Steven P; Seed, Mike

2016-10-01

To investigate preoperative cerebral hemodynamics in newborns with congenital heart disease. We hypothesized that cerebral blood flow and oxygen delivery would be decreased in newborns with congenital heart disease compared with controls. Using a "feed-and-sleep" approach to performing neonatal magnetic resonance imaging, we measured cerebral blood flow by using a slice prescription perpendicular to the right and left internal carotid arteries and basilar artery at the level of the clivus. We calculated brain volume by segmenting a 3-dimensional steady-state free procession acquisition of the whole brain, allowing quantification of cerebral blood flow indexed to brain volume. Cerebral oxygen delivery was calculated as the product of cerebral blood flow and preductal systemic arterial oxygen content obtained via a combination of conventional pulse oximetry and laboratory analysis of venous blood samples for hemoglobin concentration. A complete set of measurements were obtained in 32 newborns with heart disease and 31 controls. There was no difference in gestational age between the heart disease and control groups. There was no difference in cerebral blood flow compared with controls (103.5 ± 34.0 vs 119.7 ± 40.4 mL/min), whereas cerebral oxygen delivery was significantly lower in the congenital heart disease subjects (1881 ± 625.7 vs 2712 ± 915.7 mLO2/min). Ten newborns with congenital heart disease had diffuse excessive high signal intensity in their white matter and 2 had white matter injury whereas another 5 had both. Newborns with unrepaired cyanotic congenital heart disease have decreased cerebral oxygen delivery due to arterial desaturation. If brain growth and development are adversely affected through oxygen conformance, our findings could have clinical implications in terms of timing of surgical repair. Copyright © 2016 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

Ignition of steel alloys by impact of low-velocity iron/inert particles in gaseous oxygen

NASA Technical Reports Server (NTRS)

Benz, Frank J.; Mcilroy, Kenneth; Williams, Ralph E.

1988-01-01

The ignition of carbon steel and 316 and 304 stainless steels caused by the impact of low-velocity particles (a standard mixture consisting of 2 g of iron and 3 g of inert materials) in gaseous oxygen was investigated using NASA/White Sands Test Facility for the ignition test, and a subsonic particle impact chamber to accelerate the particles that were injected into flowing oxygen upstream of the target specimen. It was found that the oxygen velocities required to ignite the three alloys were the same as that required to ignite the particle mixture. Ignition occurred at oxygen velocities greater than 45 m/sec at 20 to 24 MPa and was found to be independent of pressure between 2 and 30 MPa. Comparison of the present results and the past results from Wegener (1964) with the Compressed Gas Association (CGA) oxygen velocity limits for safe operations indicates that the CGA limits may be excessively conservative at high pressures and too liberal at low pressures.

Relationship between serum substance P levels and daytime sleepiness in obstructive sleep apnea syndrome.

PubMed

Ursavas, Ahmet; Karadag, Mehmet; Ilcol, Yesim Ozarda; Burgazlioglu, Basak; Ercan, Ilker; Gozu, R Oktay

2007-05-01

We hypothesized that intermittent hypoxia might influence serum substance P levels, and that this effect might in turn contribute in excessive daytime sleepiness (EDS) in patients with obstructive sleep apnea syndrome (OSAS). Fifty-five patients with newly diagnosed OSAS and 15 age-matched nonapneic control subjects were enrolled in this study. Full polysomnography was performed in all patients. Single blood samples were drawn between 8:00 am and 9:00 am after the sleep study. Substance P levels were analyzed with a competitive enzyme immunoassay (substance P EIA kit; Cayman Chemical; Ann Arbor, MI). There were no significant differences in age, gender, body mass index, smoking habit, and snoring between the two groups. Serum substance P levels in the OSAS group were significantly lower than that in the control group (p < 0.0001). Serum substance P levels were positively correlated with rapid eye movement sleep (r = 0.330, p = 0.049) and slow-wave sleep (r = 0.324, p = 0.049) phases. Serum substance P levels were negatively correlated with Epworth sleepiness scale score (r = - 0.253, p = 0.048), number of total apneas during the night (r = - 0.247, p = 0.036), number of respiratory events during the night (r = - 0.266, p = 0.024), apnea-hypopnea index (r = - 0.287, p = 0.015), respiratory arousal index (r = - 0.267, p = 0.026), time spent in apnea and hypopnea (r = - 0.307, p = 0.01), average oxygen desaturation (r = - 0.265, p = 0.026), and oxygen desaturation index (r = - 0.254, p = 0.031). We concluded that EDS seen in some of the OSAS patients might be associated with various pathophysiologic mechanisms including substance P levels.

Effects of Pnictogen Atmosphere Annealing on Fe1+yTe0.6Se0.4

NASA Astrophysics Data System (ADS)

Yamada, Tatsuhiro; Sun, Yue; Pyon, Sunseng; Tamegai, Tsuyoshi

2016-02-01

It has been clarified that bulk superconductivity in Fe1+yTe0.6Se0.4 can be induced by annealing in an appropriate atmosphere to remove the harmful effects of excess iron. In order to clarify the details of the annealing process, we studied the changes in the physical properties and reaction products of Fe1+yTe0.6Se0.4 annealed in pnictogen (P, As, Sb) atmospheres. Crystals annealed in a pnictogen atmosphere show bulk superconductivity and the values of Tc and Jc are about 14 K and (2-4) × 105 A/cm2 (2 K, self-field), respectively. It is also found that the reaction rate increases with the increase in the saturated vapor pressure of the pnictogen. Unexpectedly, the reaction products of Fe1+yTe0.6Se0.4 after annealing in a P atmosphere mainly consist of FeTe2. In addition, the amount of P required to obtain the optimal Tc is much smaller than the amount of excess iron, which is similar to the case of oxygen annealing. P, oxygen, and to some extent As could serve as catalysts to form FeTe2 to remove excess iron.

Uncoupling and oxidative stress in liver mitochondria isolated from rats with acute iron overload.

PubMed

Pardo Andreu, G L; Inada, N M; Vercesi, A E; Curti, C

2009-01-01

One hypothesis for the etiology of cell damage arising from iron overload is that its excess selectively affects mitochondria. Here we tested the effects of acute iron overload on liver mitochondria isolated from rats subjected to a single dose of i.p. 500 mg/kg iron-dextran. The treatment increased the levels of iron in mitochondria (from 21 +/- 4 to 130 +/- 7 nmol/mg protein) and caused both lipid peroxidation and glutathione oxidation. The mitochondria of iron-treated rats showed lower respiratory control ratio in association with higher resting respiration. The mitochondrial uncoupling elicited by iron-treatment did not affect the phosphorylation efficiency or the ATP levels, suggesting that uncoupling is a mitochondrial protective mechanism against acute iron overload. Therefore, the reactive oxygen species (ROS)/H+ leak couple, functioning as a mitochondrial redox homeostatic mechanism could play a protective role in the acutely iron-loaded mitochondria.

Status of Serum and Salivary Levels of Superoxide Dismutase in Type 2 Diabetes Mellitus with Oral Manifestations: A Case Control Study.

PubMed

Madi, Medhini; Babu, Subhas; Kumari, Suchetha; Shetty, Shishir; Achalli, Sonika; Madiyal, Ananya; Bhat, Manohar

2016-11-01

Type 2 Diabetes Mellitus is a very well known metabolic disorder that has reached epidemic proportions worldwide. Evidence suggests that oxidative stress increases in Diabetes Mellitus because of the excessive production of reactive oxygen species and an impaired antioxidant defence mechanism. This study estimated, compared and correlated the serum and salivary Superoxide dismutase levels in healthy subjects and subjects with Type 2 Diabetes Mellitus having oral manifestations. In this study, serum and salivary Superoxide dismutase levels were estimated in 45 healthy subjects and 45 patients with Type 2 Diabetes Mellitus with oral manifestations. The mean serum and salivary Superoxide dismutase levels were significantly decreased in subjects with Type 2 Diabetes Mellitus with oral manifestations compared to the healthy subjects. Positive correlation in both healthy and diabetics was observed between serum and salivary samples. This study highlights that the abnormally high levels of oxidative stress in diabetics coupled with simultaneous decline in antioxidant defence mechanism results in complications in Diabetes mellitus. Thus exploring saliva for antioxidant markers that accurately reflect the redox status of the body is worthwhile.

Using dual-bacterial denitrification to improve δ15N determinations of nitrates containing mass-independent 17O

USGS Publications Warehouse

Coplen, T.B.; Böhlke, J.K.; Casciotti, K.L.

2004-01-01

The bacterial denitrification method for isotopic analysis of nitrate using N2O generated from Pseudomonas aureofaciens may overestimate δ15N values by as much as 1–2‰ for samples containing atmospheric nitrate because of mass-independent 17O variations in such samples. By analyzing such samples for δ15N and δ18O using the denitrifier Pseudomonas chlororaphis, one obtains nearly correct δ15N values because oxygen in N2O generated by P. chlororaphis is primarily derived from H2O. The difference between the apparent δ15N value determined with P. aureofaciens and that determined with P. chlororaphis, assuming mass-dependent oxygen isotopic fractionation, reflects the amount of mass-independent 17O in a nitrate sample. By interspersing nitrate isotopic reference materials having substantially different δ18O values with samples, one can normalize oxygen isotope ratios and determine the fractions of oxygen in N2O derived from the nitrate and from water with each denitrifier. This information can be used to improve δ15N values of nitrates having excess 17O. The same analyses also yield estimates of the magnitude of 17O excess in the nitrate (expressed as Δ17O) that may be useful in some environmental studies. The 1-σ uncertainties of δ15N, δ18O and Δ17O measurements are ±0.2, ±0.3 and ±5‰, respectively.

Excess oxygen limited diffusion and precipitation of iron in amorphous silicon dioxide

NASA Astrophysics Data System (ADS)

Leveneur, J.; Langlois, M.; Kennedy, J.; Metson, James B.

2017-10-01

In micro- and nano- electronic device fabrication, and particularly 3D designs, the diffusion of a metal into sublayers during annealing needs to be minimized as it is usually detrimental to device performance. Diffusion also causes the formation and growth of nanoprecipitates in solid matrices. In this paper, the diffusion behavior of low energy, low fluence, ion implanted iron into a thermally grown silicon oxide layer on silicon is investigated. Different ion beam analysis and imaging techniques were used. Magnetization measurements were also undertaken to provide evidence of nanocrystalline ordering. While standard vacuum furnace annealing and electron beam annealing lead to fast diffusion of the implanted species towards the Si/SiO2 interface, we show that furnace annealing in an oxygen rich atmosphere prevents the diffusion of iron that, in turn, limits the growth of the nanoparticles. The diffusion and particle growth is also greatly reduced when oxygen atoms are implanted in the SiO2 prior to Fe implantation, effectively acting as a diffusion barrier. The excess oxygen is hypothesized to trap Fe atoms and reduce their mean free path during the diffusion. Monte-Carlo simulations of the diffusion process which consider the random walk of Fe, Fick's diffusion of O atoms, Fe precipitation, and desorption of the SiO2 layer under the electron beam annealing were performed. Simulation results for the three preparation conditions are found in good agreement with the experimental data.

In-plane dissipation maxima and vortex-line distortions in the resistive transitions of oxygen-doped Bi2Sr2CaCu2O(8+delta) single crystals

NASA Astrophysics Data System (ADS)

Hsu, J. W. P.; Mitzi, D. B.; Kapitulnik, A.; Lee, Mark

1991-10-01

Measurements of the in-plane resistive transition of Bi2Sr2CaCu2O(8+delta) single crystals in perpendicular magnetic fields reveal that in oxygen-reduced samples a giant resistance maximum evolves with field. This is not seen in oxygenated samples with similar metallic normal resistivities. As the peak resistivity may exceed the normal resistivity, it cannot arise from ordinary vortex-motion dissipation. A model is proposed where the excess resistance results from nonrigid vortex motion coupling the out-of-plane dissipation to the in-plane resistance at temperatures where pinning effects are negligible.

Mars methane engine

NASA Technical Reports Server (NTRS)

Bui, Hung; Coletta, Chris; Debois, Alain

1994-01-01

The feasibility of an internal combustion engine operating on a mixture of methane, carbon dioxide, and oxygen has been verified by previous design groups for the Mars Methane Engine Project. Preliminary stoichiometric calculations examined the theoretical fuel-air ratios needed for the combustion of methane. Installation of a computer data acquisition system along with various ancillary components will enable the performance of the engine, running on the described methane mixture, to be optimized with respect to minimizing excess fuel. Theoretical calculations for stoichiometric combustion of methane-oxygen-carbon dioxide mixtures yielded a ratio of 1:2:4.79 for a methane-oxygen-carbon dioxide mixture. Empirical data shows the values to be closer to 1:2.33:3.69 for optimum operation.

A matrix-isolation-infrared spectroscopic study of the reactions of nitric oxide with oxygen and ozone

NASA Technical Reports Server (NTRS)

Bhatia, S. C.; Hall, J. H., Jr.

1980-01-01

An investigation of the oxidation of NO to NO2 by trapping the products of the gas-phase reactions with excess oxygen and ozone identified the transient species by their infrared spectra. The primary products of the NO + NO2 reactions were NO2, N2O3(A), N2O3(B), N2O4, and peroxy nitrate (OONO). The primary products of the NO + O3 reactions were NO2 and peroxy NO3 with the higher nitric oxides in low concentrations compared with the NO + O2 reactions. Isotopic oxygen and ozone were used to identify the infrared absorption frequency of the peroxy nitrate.

Local adaptation to osmotic environment in killifish, Fundulus heteroclitus, is supported by divergence in swimming performance but not by differences in excess post-exercise oxygen consumption or aerobic scope.

PubMed

Brennan, Reid S; Hwang, Ruth; Tse, Michelle; Fangue, Nann A; Whitehead, Andrew

2016-06-01

Regulation of internal ion homeostasis is essential for fishes inhabiting environments where salinities differ from their internal concentrations. It is hypothesized that selection will reduce energetic costs of osmoregulation in a population's native osmotic habitat, producing patterns of local adaptation. Killifish, Fundulus heteroclitus, occupy estuarine habitats where salinities range from fresh to seawater. Populations inhabiting an environmental salinity gradient differ in physiological traits associated with acclimation to acute salinity stress, consistent with local adaptation. Similarly, metabolic rates differ in populations adapted to different temperatures, but have not been studied in regard to salinity. We investigated evidence for local adaptation between populations of killifish native to fresh and brackish water habitats. Aerobic scope (the difference between minimum and maximum metabolic rates), excess post-exercise oxygen consumption, and swimming performance (time and distance to reach exhaustion) were used as proxies for fitness in fresh and brackish water treatments. Swimming performance results supported local adaptation; fish native to brackish water habitats performed significantly better than freshwater-native fish at high salinity while low salinity performance was similar between populations. However, results from metabolic measures did not support this conclusion; both populations showed an increase in resting metabolic rate and a decrease of aerobic scope in fresh water. Similarly, excess post-exercise oxygen consumption was higher for both populations in fresh than in brackish water. While swimming results suggest that environmentally dependent performance differences may be a result of selection in divergent osmotic environments, the differences between populations are not coupled with divergence in metabolic performance. Copyright © 2016 Elsevier Inc. All rights reserved.

Quantitative proteomic analysis reveals posttranslational responses to aneuploidy in yeast

PubMed Central

Dephoure, Noah; Hwang, Sunyoung; O'Sullivan, Ciara; Dodgson, Stacie E; Gygi, Steven P; Amon, Angelika; Torres, Eduardo M

2014-01-01

Aneuploidy causes severe developmental defects and is a near universal feature of tumor cells. Despite its profound effects, the cellular processes affected by aneuploidy are not well characterized. Here, we examined the consequences of aneuploidy on the proteome of aneuploid budding yeast strains. We show that although protein levels largely scale with gene copy number, subunits of multi-protein complexes are notable exceptions. Posttranslational mechanisms attenuate their expression when their encoding genes are in excess. Our proteomic analyses further revealed a novel aneuploidy-associated protein expression signature characteristic of altered metabolism and redox homeostasis. Indeed aneuploid cells harbor increased levels of reactive oxygen species (ROS). Interestingly, increased protein turnover attenuates ROS levels and this novel aneuploidy-associated signature and improves the fitness of most aneuploid strains. Our results show that aneuploidy causes alterations in metabolism and redox homeostasis. Cells respond to these alterations through both transcriptional and posttranscriptional mechanisms. DOI: http://dx.doi.org/10.7554/eLife.03023.001 PMID:25073701

Enhancement of ε-poly-L-lysine synthesis in Streptomyces by exogenous glutathione.

PubMed

Yan, Peng; Sun, Haoben; Lu, Pengqi; Liu, Haili; Tang, Lei

2018-01-01

Our previous work indicated that the vigor of Streptomyces decreased at the later stage of ε-poly-L-lysine (ε-PL) fermentation. In this study, we observed that the level of reactive oxygen species (ROS) in vivo increased sharply after 24 h, and the addition of an antioxidant glutathione (GSH) before this increase in ROS stimulated ε-PL synthesis in shake-flask fermentation. The enhancement of ε-PL production by GSH was further verified in batch and fed-batch fermentations. On a 5-l fermenter scale, the highest increasement was 68.8% in batch fermentation and the highest ε-PL level was 46.5 g l - 1 in fed-batch fermentation. The RT-qPCR analysis showed that the transcriptional level of the catalase gene was down-regulated, and the decrease in cell activity was alleviated by the addition of GSH. The results revealed that exogenous antioxidant might maintain the cell vigor by reducing the excess ROS which provided a novel approach to regulate ε-PL synthesis.

Oxidative stress and DNA damage induced by imidacloprid in zebrafish (Danio rerio).

PubMed

Ge, Weili; Yan, Saihong; Wang, Jinhua; Zhu, Lusheng; Chen, Aimei; Wang, Jun

2015-02-18

Imidacloprid is a neonicotinoid insecticide that can have negative effects on nontarget animals. The present study was conducted to assess the toxicity of various imidacloprid doses (0.3, 1.25, and 5 mg/mL) on zebrafish sampled after 7, 14, 21, and 28 days of exposure. The levels of catalase (CAT), superoxide dismutase (SOD), reactive oxygen species (ROS), glutathione-S-transferase (GST), and malondialdehyde (MDA) and the extent of DNA damage were measured to evaluate the toxicity of imidacloprid on zebrafish. SOD and GST activities were noticeably increased during early exposure but were inhibited toward the end of the exposure period. In addition, the CAT levels decreased to the control level following their elevation during early exposure. High concentrations of imidacloprid (1.25 and 5 mg/L) induced excessive ROS production and markedly increased MDA content on the 21st day of exposure. DNA damage was dose- and time-dependent. In conclusion, the present study showed that imidacloprid can induce oxidative stress and DNA damage in zebrafish.

Surface modification of mixed-phase hydrogenated TiO2 and corresponding photocatalytic response

NASA Astrophysics Data System (ADS)

Samsudin, Emy Marlina; Hamid, Sharifah Bee Abd; Juan, Joon Ching; Basirun, Wan Jefrey; Kandjani, Ahmad Esmaielzadeh

2015-12-01

Preparation of highly photo-activated TiO2 is achievable by hydrogenation at constant temperature and pressure, with controlled hydrogenation duration. The formation of surface disorders and Ti3+ is responsible for the color change from white unhydrogenated TiO2 to bluish-gray hydrogenated TiO2. This color change, together with increased oxygen vacancies and Ti3+ enhanced the solar light absorption from UV to infra-red region. Interestingly, no band gap narrowing is observed. The photocatalytic activity in the UV and visible region is controlled by Ti3+ and oxygen vacancies respectively. Both Ti3+ and oxygen vacancies increases the electron density on the catalyst surface thus facilitates rad OH radicals formation. The lifespan of surface photo-excited electrons and holes are also sustained thus prevents charge carrier recombination. However, excessive amount of oxygen vacancies deteriorates the photocatalytic activity as it serves as charge traps. Hydrogenation of TiO2 also promotes the growth of active {0 0 1} facets and facilitates the photocatalytic activity by higher concentration of surface OH radicals. However, the growth of {0 0 1} facets is small and insignificant toward the overall photo-kinetics. This work also shows that larger role is played by Ti3+ and oxygen vacancies rather than the surface disorders created during the hydrogenation process. It also demonstrates the ability of hydrogenated TiO2 to absorb wider range of photons even though at a similar band gap as unhydrogenated TiO2. In addition, the photocatalytic activity is shown to be decreased for extended hydrogenation duration due to excessive catalyst growth and loss in the total surface area. Thus, a balance in the physico-chemical properties of hydrogenated TiO2 is crucial to enhance the photocatalytic activity by simply controlling the hydrogenation duration.

Effects of circuit low-intensity resistance exercise with slow movement on oxygen consumption during and after exercise.

PubMed

Mukaimoto, Takahiro; Ohno, Makoto

2012-01-01

The purpose of this study was to examine oxygen consumption (VO(2)) during and after a single bout of low-intensity resistance exercise with slow movement. Eleven healthy men performed the following three types of circuit resistance exercise on separate days: (1) low-intensity resistance exercise with slow movement: 50% of one-repetition maximum (1-RM) and 4 s each of lifting and lowering phases; (2) high-intensity resistance exercise with normal movement: 80% of 1-RM and 1 s each of lifting and lowering phases; and (3) low-intensity resistance exercise with normal movement: 50% of 1-RM and 1 s each of lifting and lowering phases. These three resistance exercise trials were performed for three sets in a circuit pattern with four exercises, and the participants performed each set until exhaustion. Oxygen consumption was monitored continuously during exercise and for 180 min after exercise. Average VO(2) throughout the exercise session was significantly higher with high- and low-intensity resistance exercise with normal movement than with low-intensity resistance exercise with slow movement (P < 0.05); however, total VO(2) was significantly greater in low-intensity resistance exercise with slow movement than in the other trials. In contrast, there were no significant differences in the total excess post-exercise oxygen consumption among the three exercise trials. The results of this study suggest that low-intensity resistance exercise with slow movement induces much greater energy expenditure than resistance exercise with normal movement of high or low intensity, and is followed by the same total excess post-exercise oxygen consumption for 180 min after exercise.

The effect of exercise intensity and excess postexercise oxygen consumption on postprandial blood lipids in physically inactive men.

PubMed

Littlefield, Laurel A; Papadakis, Zacharias; Rogers, Katie M; Moncada-Jiménez, José; Taylor, J Kyle; Grandjean, Peter W

2017-09-01

Reductions in postprandial lipemia have been observed following aerobic exercise of sufficient energy expenditure. Increased excess postexercise oxygen consumption (EPOC) has been documented when comparing high- versus low-intensity exercise. The contribution of EPOC energy expenditure to alterations in postprandial lipemia has not been determined. The purpose of this study was to evaluate the effects of low- and high-intensity exercise on postprandial lipemia in healthy, sedentary, overweight and obese men (age, 43 ± 10 years; peak oxygen consumption, 31.1 ± 7.5 mL·kg -1 ·min -1 ; body mass index, 31.8 ± 4.5 kg/m 2 ) and to determine the contribution of EPOC to reductions in postprandial lipemia. Participants completed 4 conditions: nonexercise control, low-intensity exercise at 40%-50% oxygen uptake reserve (LI), high-intensity exercise at 70%-80% oxygen uptake reserve (HI), and HI plus EPOC re-feeding (HI+EERM), where the difference in EPOC energy expenditure between LI and HI was re-fed in the form of a sports nutrition bar (Premier Nutrition Corp., Emeryville, Calif., USA). Two hours following exercise participants ingested a high-fat (1010 kcals, 99 g sat fat) test meal. Blood samples were obtained before exercise, before the test meal, and at 2, 4, and 6 h postprandially. Triglyceride incremental area under the curve was significantly reduced following LI, HI, and HI+EERM when compared with nonexercise control (p < 0.05) with no differences between the exercise conditions (p > 0.05). In conclusions, prior LI and HI exercise equally attenuated postprandial triglyceride responses to the test meal. The extra energy expended during EPOC does not contribute significantly to exercise energy expenditure or to reductions in postprandial lipemia in overweight men.

The Growing Human Footprint on Coastal and Open-Ocean Biogeochemistry

NASA Astrophysics Data System (ADS)

Doney, Scott C.

2010-06-01

Climate change, rising atmospheric carbon dioxide, excess nutrient inputs, and pollution in its many forms are fundamentally altering the chemistry of the ocean, often on a global scale and, in some cases, at rates greatly exceeding those in the historical and recent geological record. Major observed trends include a shift in the acid-base chemistry of seawater, reduced subsurface oxygen both in near-shore coastal water and in the open ocean, rising coastal nitrogen levels, and widespread increase in mercury and persistent organic pollutants. Most of these perturbations, tied either directly or indirectly to human fossil fuel combustion, fertilizer use, and industrial activity, are projected to grow in coming decades, resulting in increasing negative impacts on ocean biota and marine resources.

The growing human footprint on coastal and open-ocean biogeochemistry.

PubMed

Doney, Scott C

2010-06-18

Climate change, rising atmospheric carbon dioxide, excess nutrient inputs, and pollution in its many forms are fundamentally altering the chemistry of the ocean, often on a global scale and, in some cases, at rates greatly exceeding those in the historical and recent geological record. Major observed trends include a shift in the acid-base chemistry of seawater, reduced subsurface oxygen both in near-shore coastal water and in the open ocean, rising coastal nitrogen levels, and widespread increase in mercury and persistent organic pollutants. Most of these perturbations, tied either directly or indirectly to human fossil fuel combustion, fertilizer use, and industrial activity, are projected to grow in coming decades, resulting in increasing negative impacts on ocean biota and marine resources.

Cardiac-specific ablation of glutaredoxin 3 leads to cardiac hypertrophy and heart failure

USDA-ARS?s Scientific Manuscript database

Experimental and clinical investigations have demonstrated that reactive oxygen species (ROS) production is increased during cardiac hypertrophy and heart failure. Excess ROS can directly impair cardiac contraction through modification of Ca2+ handling proteins or activate multiple effectors and sig...

Iron homeostasis and eye disease

PubMed Central

Loh, Allison; Hadziahmetovic, Majda; Dunaief, Joshua L.

2009-01-01

Summary Iron is necessary for life, but excess iron can be toxic to tissues. Iron is thought to damage tissues primarily by generating oxygen free radicals through the Fenton reaction. We present an overview of the evidence supporting iron's potential contribution to a broad range of eye disease using an anatomical approach. Firstly, iron can be visualized in the cornea as iron lines in the normal aging cornea as well as in diseases like keratoconus and pterygium. In the lens, we present the evidence for the role of oxidative damage in cataractogenesis. Also, we review the evidence that iron may play a role in the pathogenesis of the retinal disease age-related macular degeneration. Although currently there is no direct link between excess iron and development of optic neuropathies, ferrous iron's ability to form highly reactive oxygen species may play a role in optic nerve pathology. Lastly, we discuss recent advances in prevention and therapeutics for eye disease with antioxidants and iron chelators,. PMID:19059309

On the origin of blue emission from ZnO quantum dots synthesized by a sol-gel route

NASA Astrophysics Data System (ADS)

Han, Li-Li; Cui, Lan; Wang, Wei-Hua; Wang, Jiang-Long; Du, Xi-Wen

2012-06-01

ZnO quantum dots (QDs) with blue emission were synthesized by a sol-gel method. A series of control experiments were conducted to explore the origin of the blue emission. It is found that the blue emission arises from neither the quantum confinement nor intermediate products, and it can be achieved only in the presence of Li+ cations and excessive OH- anions. Moreover, the long decay time of the blue emission suggests a defect-related de-excitation process. On the basis of the experimental and calculation results, possible de-excitation paths for light emission were discussed, and the origin of the blue emission was determined as the electron transition from the conduction band to interstitial oxygen defects. Excessive OH- anions are responsible for the formation of interstitial oxygen defects, and Li+ ions can stabilize the defects by substituting for Zn atoms. Besides, Li+ ions can block the growth of ZnO QDs, broaden their band gap and cause a blue shift of the blue emission.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Twu, Nancy; Metzger, Michael; Balasubramanian, Mahalingam

Here, the lithium-excess Li xNi 2-4x/3Sb x/3O 2 (LNSO) materials were previously shown to demonstrate higher capacities and improved cyclability with increasing lithium content. While the performance trend is promising, observed capacities are much lower than theoretical capacities, pointing to a need for further understanding of active redox processes in these materials. In this work, we study the electrochemical behavior of the LNSO materials as a function of lithium content and at slow and fast rates. Surprisingly, Li 1.15Ni 0.47Sb 0.38O 2 (LNSO-15) exhibits higher discharge capacities at faster rates and traverses distinct voltage curves at slow and fast rates.more » To understand these two peculiarities, we characterize the redox activity of nickel, antimony, and oxygen at different rates. While experiments confirm some nickel redox activity and oxygen loss, these two mechanisms cannot account for all observed capacity. We propose that the balance of the observed capacity may be due reversible oxygen redox and that the rate-dependent voltage curve features may derive from irreversible nickel migration occurring on slow charge. As future high energy density cathodes are likely to contain both lithium excess and high nickel content, both of these findings have important implications for the development of novel high capacity cathode materials.« less

Study of the structure, dielectric and ferroelectric behavior of BaBi4+δTi4O15 ceramics

NASA Astrophysics Data System (ADS)

Khokhar, Anita; Goyal, Parveen K.; Thakur, O. P.; Sreenivas, K.

2016-05-01

The structure and ferroelectric properties of excess bismuth doped barium bismuth titanate BaBi4+δTi4O15 (δ = 2 - 10 wt.%)) ceramics prepared by solid-state reaction method have been investigated. X-ray diffraction (XRD) confirms the formation of a single phase material with a change in the orthorhombic distortion with varying excess of bismuth content. There is no change in the phase transition temperature (Tm) while the relaxor behaviour has been modified significantly with excess of bismuth doping. Saturated hysteresis loops with high remnant polarization (Pr ~ 12.5 µC/cm2), low coercive fields (Ec ~ 26 kV/cm) are measured and a high piezoelectric coefficient (d33 ~ 29 pC/N) is achieved in poled BaBi4Ti4O15 ceramics prepared with up to 8 wt.% of excess bismuth oxide. The improvement in the ferroelectric properties with increase in the excess bismuth content in BaBi4Ti4O15 ceramics has been explained in terms of changing oxygen vacancy concentration and structural relaxation. Tunable ferroelectric materials can be obtained by manipulating the doping amount of excess bismuth.

Excess iodine promotes apoptosis of thyroid follicular epithelial cells by inducing autophagy suppression and is associated with Hashimoto thyroiditis disease.

PubMed

Xu, Chengcheng; Wu, Fei; Mao, Chaoming; Wang, Xuefeng; Zheng, Tingting; Bu, Ling; Mou, Xiao; Zhou, Yuepeng; Yuan, Guoyue; Wang, Shengjun; Xiao, Yichuan

2016-12-01

The incidence of the autoimmune thyroid disease Hashimoto thyroiditis (HT) has increased in recent years, and increasing evidence supports the contribution of excess iodine intake to thyroid disease. In this study, we examined the status of autophagy and apoptosis in thyroid tissues obtained from patients with HT, and we determined the effects of excessive iodine on the autophagy and apoptosis of thyroid follicular cells (TFCs) in an attempt to elucidate the effects of excess iodine on HT development. Our results showed decreases in the autophagy-related protein LC3B-II, and increases in caspase-3 were observed in thyroid tissues from HT patients. Interestingly, the suppression of autophagy activity in TFCs was induced by excess iodine in vitro, and this process is mediated through transforming growth factor-β1 downregulation and activation of the Akt/mTOR signaling pathway. In addition, excess iodine induced autophagy suppression and enhanced reactive oxygen species (ROS) production and apoptosis of TFCs, which could be rescued by the activation of autophagy. Taken together, our results demonstrated that excess iodine contributed to autophagy suppression and apoptosis of TFCs, which could be important factors predisposing to increased risk of HT development. Copyright © 2016 Elsevier Ltd. All rights reserved.

Senp1 drives hypoxia-induced polycythemia via GATA1 and Bcl-xL in subjects with Monge’s disease

PubMed Central

Azad, Priti; Zhao, Huiwen W.; Ronen, Roy; Zhou, Dan; Poulsen, Orit; Hsiao, Yu Hsin; Bafna, Vineet

2016-01-01

In this study, because excessive polycythemia is a predominant trait in some high-altitude dwellers (chronic mountain sickness [CMS] or Monge’s disease) but not others living at the same altitude in the Andes, we took advantage of this human experiment of nature and used a combination of induced pluripotent stem cell technology, genomics, and molecular biology in this unique population to understand the molecular basis for hypoxia-induced excessive polycythemia. As compared with sea-level controls and non-CMS subjects who responded to hypoxia by increasing their RBCs modestly or not at all, respectively, CMS cells increased theirs remarkably (up to 60-fold). Although there was a switch from fetal to adult HgbA0 in all populations and a concomitant shift in oxygen binding, we found that CMS cells matured faster and had a higher efficiency and proliferative potential than non-CMS cells. We also established that SENP1 plays a critical role in the differential erythropoietic response of CMS and non-CMS subjects: we can convert the CMS phenotype into that of non-CMS and vice versa by altering SENP1 levels. We also demonstrated that GATA1 is an essential downstream target of SENP1 and that the differential expression and response of GATA1 and Bcl-xL are a key mechanism underlying CMS pathology. PMID:27821551

Senp1 drives hypoxia-induced polycythemia via GATA1 and Bcl-xL in subjects with Monge's disease.

PubMed

Azad, Priti; Zhao, Huiwen W; Cabrales, Pedro J; Ronen, Roy; Zhou, Dan; Poulsen, Orit; Appenzeller, Otto; Hsiao, Yu Hsin; Bafna, Vineet; Haddad, Gabriel G

2016-11-14

In this study, because excessive polycythemia is a predominant trait in some high-altitude dwellers (chronic mountain sickness [CMS] or Monge's disease) but not others living at the same altitude in the Andes, we took advantage of this human experiment of nature and used a combination of induced pluripotent stem cell technology, genomics, and molecular biology in this unique population to understand the molecular basis for hypoxia-induced excessive polycythemia. As compared with sea-level controls and non-CMS subjects who responded to hypoxia by increasing their RBCs modestly or not at all, respectively, CMS cells increased theirs remarkably (up to 60-fold). Although there was a switch from fetal to adult HgbA0 in all populations and a concomitant shift in oxygen binding, we found that CMS cells matured faster and had a higher efficiency and proliferative potential than non-CMS cells. We also established that SENP1 plays a critical role in the differential erythropoietic response of CMS and non-CMS subjects: we can convert the CMS phenotype into that of non-CMS and vice versa by altering SENP1 levels. We also demonstrated that GATA1 is an essential downstream target of SENP1 and that the differential expression and response of GATA1 and Bcl-xL are a key mechanism underlying CMS pathology. © 2016 Azad et al.

A cerium oxide nanoparticle-based device for the detection of chronic inflammation via optical and magnetic resonance imaging

NASA Astrophysics Data System (ADS)

Kaittanis, Charalambos; Santra, Santimukul; Asati, Atul; Perez, J. Manuel

2012-03-01

Monitoring of microenvironmental parameters is critical in healthcare and disease management. Harnessing the antioxidant activity of nanoceria and the imaging capabilities of iron oxide nanoparticles in a device setup, we were able to image changes in the device's aqueous milieu. The device was able to convey and process changes in the microenvironment's pH and reactive oxygen species' concentration, distinguishing physiological from abnormal levels. As a result under physiological and transient inflammatory conditions, the device's fluorescence and magnetic resonance signals, emanating from multimodal iron oxide nanoparticles, were similar. However, under chronic inflammatory conditions that are usually associated with high local concentrations of reactive oxygen species and pH decrease, the device's output was considerably different. Specifically, the device's fluorescence emission significantly decreased, while the magnetic resonance signal T2 increased. Further studies identified that the changes in the device's output are attributed to inactivation of the sensing component's nanoceria that prevents it from successfully scavenging the generated free radicals. Interestingly, the buildup of free radical excess led to polymerization of the iron oxide nanoparticle's coating, with concomitant formation of micron size aggregates. Our studies indicate that a nanoceria-based device can be utilized for the monitoring of pro-inflammatory biomarkers, having important applications in the management of numerous ailments while eliminating nanoparticle toxicity issues.Monitoring of microenvironmental parameters is critical in healthcare and disease management. Harnessing the antioxidant activity of nanoceria and the imaging capabilities of iron oxide nanoparticles in a device setup, we were able to image changes in the device's aqueous milieu. The device was able to convey and process changes in the microenvironment's pH and reactive oxygen species' concentration, distinguishing physiological from abnormal levels. As a result under physiological and transient inflammatory conditions, the device's fluorescence and magnetic resonance signals, emanating from multimodal iron oxide nanoparticles, were similar. However, under chronic inflammatory conditions that are usually associated with high local concentrations of reactive oxygen species and pH decrease, the device's output was considerably different. Specifically, the device's fluorescence emission significantly decreased, while the magnetic resonance signal T2 increased. Further studies identified that the changes in the device's output are attributed to inactivation of the sensing component's nanoceria that prevents it from successfully scavenging the generated free radicals. Interestingly, the buildup of free radical excess led to polymerization of the iron oxide nanoparticle's coating, with concomitant formation of micron size aggregates. Our studies indicate that a nanoceria-based device can be utilized for the monitoring of pro-inflammatory biomarkers, having important applications in the management of numerous ailments while eliminating nanoparticle toxicity issues. Electronic supplementary information (ESI) available: ESI figures. See DOI: 10.1039/c2nr11956k

The mechanism of the photochemical oxidation of water to oxygen with silver chloride colloids

NASA Astrophysics Data System (ADS)

Chandrasekaran, K.; Thomas, J. K.

1983-05-01

Photoexcitation of silver chloride colloids in the presence of excess silver ions, leads to the decomposition of water. Hydroxyl radicals were found to be intermediates in the decomposition process. Irradiation leads to hydroxyl radicals, which recombine to give hydrogen peroxide, on the colloidal particle surface. Subsequent decomposition of H 2O 2 to give O 2 is catalyzed by silver ions. Addition of alcohols such as methanol and isopropanol reduce the oxygen yield, as they react with OH radicals and reduce the H 2O 2 yield.

Beta-hydroxybutyrate increases reactive oxygen species in late but not in early postimplantation embryonic cells in vitro.

PubMed

Forsberg, H; Eriksson, U J; Melefors, O; Welsh, N

1998-02-01

Embryonic dysmorphogenesis has been blocked by antioxidant treatment in vivo and in vitro, suggesting that embryonic excess of reactive oxygen species (ROS) has a role in the teratogenic process of diabetic pregnancy. We report that the basal levels of ROS in dispersed rat embryonic cells in vitro, as determined by fluorescence of dichlorofluorescein (DCF), were not different in cells from control and diabetic pregnancy at day 10 or 12. Beta-hydroxybutyrate (beta-HB) and succinic acid monomethyl ester both augmented DCF fluorescence in cells from day 12 embryos of normal and diabetic rats but not from day 10 embryos. Cells of day 10 and day 12 embryos from normal and diabetic rats responded to increasing glucose concentrations with a dosage-dependent alleviation of DCF fluorescence. Day 10 embryonic cells exhibited high glucose utilization rates and high pentose phosphate shunt rates, but low mitochondrial oxidation rates. Moreover, in vitro culture of embryos between gestational days 9 and 10 in the presence of 20% oxygen induced an increased and glucose-sensitive oxidation of glucose compared with embryos not cultured in vitro. At gestation day 12, however, pentose phosphate shunt rates showed a decrease, whereas the mitochondrial beta-HB oxidation rates were increased compared with those at gestation day 10. This was paralleled by a lower expression of glucose 6-phosphate dehydrogenase- and phosphofructokinase-mRNA levels at day 12 than at day 10. On the other hand, H-ferritin mRNA expression at day 12 was high compared with day 10. None of the mRNA species investigated were affected by the diabetic state of the mother. It was concluded that beta-HB-induced stimulation of mitochondrial oxidative events may lead to the generation of ROS at gestational day 12, but probably not at day 10, when only a minute amount of mitochondrial activity occurs. Thus our results do not support the notion of diabetes-induced mitochondrial oxidative stress before the development of a placental supply of oxygen.

The Risk of Oxygen during Cardiac Surgery (ROCS) trial: study protocol for a randomized clinical trial.

PubMed

Lopez, Marcos G; Pretorius, Mias; Shotwell, Matthew S; Deegan, Robert; Eagle, Susan S; Bennett, Jeremy M; Sileshi, Bantayehu; Liang, Yafen; Gelfand, Brian J; Kingeter, Adam J; Siegrist, Kara K; Lombard, Frederick W; Richburg, Tiffany M; Fornero, Dane A; Shaw, Andrew D; Hernandez, Antonio; Billings, Frederic T

2017-06-26

Anesthesiologists administer excess supplemental oxygen (hyper-oxygenation) to patients during surgery to avoid hypoxia. Hyper-oxygenation, however, may increase the generation of reactive oxygen species and cause oxidative damage. In cardiac surgery, increased oxidative damage has been associated with postoperative kidney and brain injury. We hypothesize that maintenance of normoxia during cardiac surgery (physiologic oxygenation) decreases kidney injury and oxidative damage compared to hyper-oxygenation. The Risk of Oxygen during Cardiac Surgery (ROCS) trial will randomly assign 200 cardiac surgery patients to receive physiologic oxygenation, defined as the lowest fraction of inspired oxygen (FIO 2 ) necessary to maintain an arterial hemoglobin saturation of 95 to 97%, or hyper-oxygenation (FIO 2  = 1.0) during surgery. The primary clinical endpoint is serum creatinine change from baseline to postoperative day 2, and the primary mechanism endpoint is change in plasma concentrations of F 2 -isoprostanes and isofurans. Secondary endpoints include superoxide production, clinical delirium, myocardial injury, and length of stay. An endothelial function substudy will examine the effects of oxygen treatment and oxidative stress on endothelial function, measured using flow mediated dilation, peripheral arterial tonometry, and wire tension myography of epicardial fat arterioles. The ROCS trial will test the hypothesis that intraoperative physiologic oxygenation decreases oxidative damage and organ injury compared to hyper-oxygenation in patients undergoing cardiac surgery. ClinicalTrials.gov, ID: NCT02361944 . Registered on the 30th of January 2015.

SOD1 aggregation in astrocytes following ischemia/reperfusion injury: a role of NO-mediated S-nitrosylation of protein disulfide isomerase (PDI).

PubMed

Chen, Xueping; Guan, Teng; Li, Chen; Shang, Huifang; Cui, Liying; Li, Xin-Min; Kong, Jiming

2012-10-12

Ubiquitinated-protein aggregates are implicated in cerebral ischemia/reperfusion injury. The very presence of these ubiquitinated-protein aggregates is abnormal and seems to be disease-related. However, it is not clear what leads to aggregate formation and whether the aggregations represent a reaction to aggregate-mediated neurodegeneration. To study the nitrosative stress-induced protein aggregation in cerebral ischemia/reperfusion injury, we used primary astrocyte cultures as a cell model, and systematically examined their iNOS expression and consequent NO generation following oxygen glucose deprivation and reperfusion. The expression of protein disulfide isomerase (PDI) and copper-zinc superoxide dismutase (SOD1) were also examined, and the biochemical interaction between PDI and SOD1 was determined by immunoprecipitation. In addition, the levels of S-nitrosylated PDI in cultured astrocytes after oxygen glucose deprivation and reperfusion treatment were measured using the biotin-switch assay. The formation of ubiquitinated-protein aggregates was detected by immunoblot and immunofluorescence staining. Our data showed that the up-regulation of iNOS expression after oxygen glucose deprivation and reperfusion treatment led to excessive NO generation. Up-regulation of PDI and SOD1 was also identified in cultured astrocytes following oxygen glucose deprivation and reperfusion, and these two proteins were found to bind to each other. Furthermore, the increased nitrosative stress due to ischemia/reperfusion injury was highly associated with NO-induced S-nitrosylation of PDI, and this S-nitrosylation of PDI was correlated with the formation of ubiquitinated-protein aggregates; the levels of S-nitrosylated PDI increased in parallel with the formation of aggregates. When NO generation was pharmacologically inhibited by iNOS specific inhibitor 1400W, S-nitrosylation of PDI was significantly blocked. In addition, the formation of ubiquitinated-protein aggregates in cultured astrocytes following oxygen glucose deprivation and reperfusion was also suppressed by 1400W. Interestingly, these aggregates were colocalized with SOD1, which was found to co-immunoprecipitate with PDI. NO-mediated S-nitrosylation of PDI may be involved in the formation of the SOD1-linked ubiquitinated-protein aggregates in cerebral ischemia/reperfusion injury.

Therapeutic Targeting of the Mitochondria Initiates Excessive Superoxide Production and Mitochondrial Depolarization Causing Decreased mtDNA Integrity

PubMed Central

Pokrzywinski, Kaytee L.; Biel, Thomas G.; Kryndushkin, Dmitry; Rao, V. Ashutosh

2016-01-01

Mitochondrial dysregulation is closely associated with excessive reactive oxygen species (ROS) production. Altered redox homeostasis has been implicated in the onset of several diseases including cancer. Mitochondrial DNA (mtDNA) and proteins are particularly sensitive to ROS as they are in close proximity to the respiratory chain (RC). Mitoquinone (MitoQ), a mitochondria-targeted redox agent, selectively damages breast cancer cells possibly through damage induced via enhanced ROS production. However, the effects of MitoQ and other triphenylphosphonium (TPP+) conjugated agents on cancer mitochondrial homeostasis remain unknown. The primary objective of this study was to determine the impact of mitochondria-targeted agent [(MTAs) conjugated to TPP+: mitoTEMPOL, mitoquinone and mitochromanol-acetate] on mitochondrial physiology and mtDNA integrity in breast (MDA-MB-231) and lung (H23) cancer cells. The integrity of the mtDNA was assessed by quantifying the degree of mtDNA fragmentation and copy number, as well as by measuring mitochondrial proteins essential to mtDNA stability and maintenance (TFAM, SSBP1, TWINKLE, POLG and POLRMT). Mitochondrial status was evaluated by measuring superoxide production, mitochondrial membrane depolarization, oxygen consumption, extracellular acidification and mRNA or protein levels of the RC complexes along with TCA cycle activity. In this study, we demonstrated that all investigated MTAs impair mitochondrial health and decrease mtDNA integrity in MDA-MB-231 and H23 cells. However, differences in the degree of mitochondrial damage and mtDNA degradation suggest unique properties among each MTA that may be cell line, dose and time dependent. Collectively, our study indicates the potential for TPP+ conjugated molecules to impair breast and lung cancer cells by targeting mitochondrial homeostasis. PMID:28030582

Therapeutic Targeting of the Mitochondria Initiates Excessive Superoxide Production and Mitochondrial Depolarization Causing Decreased mtDNA Integrity.

PubMed

Pokrzywinski, Kaytee L; Biel, Thomas G; Kryndushkin, Dmitry; Rao, V Ashutosh

2016-01-01

Mitochondrial dysregulation is closely associated with excessive reactive oxygen species (ROS) production. Altered redox homeostasis has been implicated in the onset of several diseases including cancer. Mitochondrial DNA (mtDNA) and proteins are particularly sensitive to ROS as they are in close proximity to the respiratory chain (RC). Mitoquinone (MitoQ), a mitochondria-targeted redox agent, selectively damages breast cancer cells possibly through damage induced via enhanced ROS production. However, the effects of MitoQ and other triphenylphosphonium (TPP+) conjugated agents on cancer mitochondrial homeostasis remain unknown. The primary objective of this study was to determine the impact of mitochondria-targeted agent [(MTAs) conjugated to TPP+: mitoTEMPOL, mitoquinone and mitochromanol-acetate] on mitochondrial physiology and mtDNA integrity in breast (MDA-MB-231) and lung (H23) cancer cells. The integrity of the mtDNA was assessed by quantifying the degree of mtDNA fragmentation and copy number, as well as by measuring mitochondrial proteins essential to mtDNA stability and maintenance (TFAM, SSBP1, TWINKLE, POLG and POLRMT). Mitochondrial status was evaluated by measuring superoxide production, mitochondrial membrane depolarization, oxygen consumption, extracellular acidification and mRNA or protein levels of the RC complexes along with TCA cycle activity. In this study, we demonstrated that all investigated MTAs impair mitochondrial health and decrease mtDNA integrity in MDA-MB-231 and H23 cells. However, differences in the degree of mitochondrial damage and mtDNA degradation suggest unique properties among each MTA that may be cell line, dose and time dependent. Collectively, our study indicates the potential for TPP+ conjugated molecules to impair breast and lung cancer cells by targeting mitochondrial homeostasis.

Anti-Oxidative Effects of Rooibos Tea (Aspalathus linearis) on Immobilization-Induced Oxidative Stress in Rat Brain

PubMed Central

Kim, Hyun-Pyo

2014-01-01

Exposure to chronic psychological stress may be related to increased reactive oxygen species (ROS) or free radicals, and thus, long-term exposure to high levels of oxidative stress may cause the accumulation of oxidative damage and eventually lead to many neurodegenerative diseases. Compared with other organs, the brain appears especially susceptible to excessive oxidative stress due to its high demand for oxygen. In the case of excessive ROS production, endogenous defense mechanisms against ROS may not be sufficient to suppress ROS-associated oxidative damage. Dietary antioxidants have been shown to protect neurons against a variety of experimental neurodegenerative conditions. In particular, Rooibos tea might be a good source of antioxidants due to its larger proportion of polyphenolic compounds. An optimal animal model for stress should show the features of a stress response and should be able to mimic natural stress progression. However, most animal models of stress, such as cold-restraint, electric foot shock, and burn shock, usually involve physical abuse in addition to the psychological aspects of stress. Animals subjected to chronic restraint or immobilization are widely believed to be a convenient and reliable model to mimic psychological stress. Therefore, in the present study, we propose that immobilization-induced oxidative stress was significantly attenuated by treatment with Rooibos tea. This conclusion is demonstrated by Rooibos tea’s ability to (i) reverse the increase in stress-related metabolites (5-HIAA and FFA), (ii) prevent lipid peroxidation (LPO), (iii) restore stress-induced protein degradation (PD), (iv) regulate glutathione metabolism (GSH and GSH/GSSG ratio), and (v) modulate changes in the activities of antioxidant enzymes (SOD and CAT). PMID:24466326

Steap4 Plays a Critical Role in Osteoclastogenesis in Vitro by Regulating Cellular Iron/Reactive Oxygen Species (ROS) Levels and cAMP Response Element-binding Protein (CREB) Activation*

PubMed Central

Zhou, Jian; Ye, Shiqiao; Fujiwara, Toshifumi; Manolagas, Stavros C.; Zhao, Haibo

2013-01-01

Iron is essential for osteoclast differentiation, and iron overload in a variety of hematologic diseases is associated with excessive bone resorption. Iron uptake by osteoclast precursors via the transferrin cycle increases mitochondrial biogenesis, reactive oxygen species production, and activation of cAMP response element-binding protein, a critical transcription factor downstream of receptor activator of NF-κB-ligand-induced calcium signaling. These changes are required for the differentiation of osteoclast precursors to mature bone-resorbing osteoclasts. However, the molecular mechanisms regulating cellular iron metabolism in osteoclasts remain largely unknown. In this report, we provide evidence that Steap4, a member of the six-transmembrane epithelial antigen of prostate (Steap) family proteins, is an endosomal ferrireductase with a critical role in cellular iron utilization in osteoclasts. Specifically, we show that Steap4 is the only Steap family protein that is up-regulated during osteoclast differentiation. Knocking down Steap4 expression in vitro by lentivirus-mediated short hairpin RNAs inhibits osteoclast formation and decreases cellular ferrous iron, reactive oxygen species, and the activation of cAMP response element-binding protein. These results demonstrate that Steap4 is a critical enzyme for cellular iron uptake and utilization in osteoclasts and, thus, indispensable for osteoclast development and function. PMID:23990467

Effects of hyperbaric, normobaric and hypobaric oxygen supplementation on retinal vessels in newborn rats: a preliminary study.

PubMed

Ricci, B

1987-03-01

An experimental study was conducted on eight litters of newborn rats to evaluate the effects of supplemental oxygen administration on the retinal vasculature. The animals and their mothers were kept inside a pressure chamber and treated for the first 5 days of life. On the sixth day, they were removed and kept for five more days under room air and normobaric conditions. Three litters received continuous flow oxygen at 80% at a compression pressure of +81 kPa, one litter oxygen at 80% at a pressure of -39.5 kPa atms and three other litters received oxygen at 80% under normobaric conditions. The eighth litter was treated with room air oxygen at a compression pressure of +81 kPa. A severe retinopathy with marked retinal neovascularization was seen only in the newborn animals of the litters that received oxygen supplementation under normobaric or hypobaric conditions. Retinal vessels showed no pathological changes in the litters treated with hyperbaric normoxia or hyperoxia. It is possible to hypothesize that the prolonged period of oxygen supplementation failed to produce harmful effects on the retinal vasculature because the moderate hyperbarism caused mild retinal and choroidal vasoconstriction thus preventing excessive oxygen transport to the inner retina from the choroid during hyperoxia without inducing structural damage to the retinal tissue.

Methane Pyrolysis and Disposing Off Resulting Carbon

NASA Technical Reports Server (NTRS)

Sharma, P. K.; Rapp, D.; Rahotgi, N. K.

1999-01-01

Sabatier/Electrolysis (S/E) is a leading process for producing methane and oxygen for application to Mars ISPP. One significant problem with this process is that it produces an excess of methane for combustion with the amount of oxygen that is produced. Therefore, one must discard roughly half of the methane to obtain the proper stoichiometric methane/oxygen mixture for ascent from Mars. This is a waste of hydrogen, which must be brought from Earth and is difficult to transport to Mars and store on Mars. To reduce the problem of transporting hydrogen to Mars, the S/E process can be augmented by another process which reduces overall hydrogen requirement. Three conceptual approaches for doing this are (i) recover hydrogen from the excess methane produced by the S/E process, (ii) convert the methane to a higher hydrocarbon or other organic with a lower H/C ratio than methane, and (iii) use a separate process (such as zirconia or reverse water gas shift reaction) to produce additional oxygen, thus utilizing all the methane produced by the Sabatier process. We report our results here on recovering hydrogen from the excess methane using pyrolysis of methane. Pyrolysis has the advantage that it produces almost pure hydrogen, and any unreacted methane can pass through the S/E process reactor. It has the disadvantage that disposing of the carbon produced by pyrolysis presents difficulties. The goals of a research program on recovery of hydrogen from methane are (in descending priority order): 1) Study the kinetics of pyrolysis to arrive at a pyrolysis reactor design that produces high yields in a confined volume at the lowest possible operating temperature; 2) Study the kinetics of carbon burnoff to determine whether high yields can be obtained in a confined volume at acceptable operating temperatures; and 3) Investigate catalytic techniques for depositing carbon as a fine soot which can be physically separated from the reactor. In the JPL program, we have made significant measurements in regard to goal 1, cursory measurements in regard to goal 2, and would plan to pursue goal 3 if additional resources are secured.

The importance of controlling in vitro oxygen tension to accurately model in vivo neurophysiology.

PubMed

Bordt, Evan A

2018-05-01

The majority of in vitro studies modeling in vivo conditions are performed on the lab bench in atmospheric air. However, the oxygen tension (pO 2 ) present in atmospheric air (160mm Hg, ∼21% O 2 ) is in great excess to the pO 2 that permeates tissues within the brain (5-45mm Hg, ∼1-6% O 2 ). This review will discuss the differentiation between pO 2 in the in vivo environment and the pO 2 commonly used during in vitro experiments, and how this could affect assay outcomes. Also highlighted are studies linking changes in pO 2 to changes in cellular function, particularly the role of pO 2 in mitochondrial function, reactive oxygen species production, and cellular growth and differentiation. The role of hypoxia inducible factor 1 and oxygen sensing is also presented. Finally, emerging literature exploring sex differences in tissue oxygenation is discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

The preparation of calcium superoxide from calcium peroxide diperoxyhydrate

NASA Technical Reports Server (NTRS)

Ballou, E. V.; Wood, P. C.; Spitze, L. A.; Wydeven, T.

1977-01-01

There is interest in solid materials containing a high percentage of stored oxygen for use in emergency breathing apparatus for miners and as auxiliary oxygen sources for astronauts. In theory, the amount of available oxygen in calcium superoxide, Ca(O2)2 is higher than in potassium superoxide, KO2, and its availability during use should be unhindered by the formation of a low melting and hydrous coating. The decomposition of solid calcium peroxide diperoxyhydrate, CaO2.2H2O2 has been studied, using an apparatus which allows good control of the critical reaction parameters. Samples have been prepared showing apparent superoxide contents in excess of those previously reported and higher than the theoretical 58.4% expected from a disproportionation reaction.

Three-Body Forces and the Limit of Oxygen Isotopes

NASA Astrophysics Data System (ADS)

Otsuka, Takaharu; Suzuki, Toshio; Holt, Jason D.; Schwenk, Achim; Akaishi, Yoshinori

2010-07-01

The limit of neutron-rich nuclei, the neutron drip line, evolves regularly from light to medium-mass nuclei except for a striking anomaly in the oxygen isotopes. This anomaly is not reproduced in shell-model calculations derived from microscopic two-nucleon forces. Here, we present the first microscopic explanation of the oxygen anomaly based on three-nucleon forces that have been established in few-body systems. This leads to repulsive contributions to the interactions among excess neutrons that change the location of the neutron drip line from O28 to the experimentally observed O24. Since the mechanism is robust and general, our findings impact the prediction of the most neutron-rich nuclei and the synthesis of heavy elements in neutron-rich environments.

A critical role of acute bronchoconstriction in the mortality associated with high-dose sarin inhalation: Effects of epinephrine and oxygen therapies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gundavarapu, Sravanthi; Zhuang, Jianguo; Barrett, Edward G.

Sarin is an organophosphate nerve agent that is among the most lethal chemical toxins known to mankind. Because of its vaporization properties and ease and low cost of production, sarin is the nerve agent with a strong potential for use by terrorists and rouge nations. The primary route of sarin exposure is through inhalation and, depending on the dose, sarin leads to acute respiratory failure and death. The mechanism(s) of sarin-induced respiratory failure is poorly understood. Sarin irreversibly inhibits acetylcholine esterase, leading to excessive synaptic levels of acetylcholine and, we have previously shown that sarin causes marked ventilatory changes includingmore » weakened response to hypoxia. We now show that LD{sub 50} sarin inhalation causes severe bronchoconstriction in rats, leading to airway resistance, increased hypoxia-induced factor-1α, and severe lung epithelium injury. Transferring animals into 60% oxygen chambers after sarin exposure improved the survival from about 50% to 75% at 24 h; however, many animals died within hours after removal from the oxygen chambers. On the other hand, if LD{sub 50} sarin-exposed animals were administered the bronchodilator epinephrine, > 90% of the animals survived. Moreover, while both epinephrine and oxygen treatments moderated cardiorespiratory parameters, the proinflammatory cytokine surge, and elevated expression of hypoxia-induced factor-1α, only epinephrine consistently reduced the sarin-induced bronchoconstriction. These data suggest that severe bronchoconstriction is a critical factor in the mortality induced by LD{sub 50} sarin inhalation, and epinephrine may limit the ventilatory, inflammatory, and lethal effects of sarin. - Highlights: • Inhalation exposure of rats to LD{sub 50} sarin causes death through respiratory failure. • Severe bronchoconstriction is the major cause of sarin-induced respiratory failure. • Transfer of sarin exposed rats to 60% oxygen improves the mortality temporarily. • Epinephrine improves bronchoconstriction and mortality in LD{sub 50} sarin-exposed rats. • Both epinephrine and oxygen moderate the sarin-induced lung inflammatory response.« less

Blood-Injection-Injury (B-I-I) Specific Phobia Affects the Outcome of Hypoxic Challenge Testing.

PubMed

Spurling, Kristofer J; McGoldrick, Veronica P

2017-05-01

Blood-injection-injury (B-I-I) phobia is capable of producing inaccurate hypoxic challenge testing results due to anxiety-induced hyperventilation. A 69-yr-old woman with a history of hypersensitivity pneumonitis, restrictive spirometry, exercise desaturation requiring supplementary oxygen on mobilizing, reduced DLco, and B-I-I phobia was referred for hypoxic challenge testing (HCT) to assess in-flight oxygen requirements. HCT was performed by breathing a 15% FIo2 gas mixture, simulating the available oxygen in ambient air onboard aircraft pressurized to an equivalent altitude of 8000 ft. Spo2 fell to a nadir value of 81% during HCT, although it rapidly increased to 89% during the first of two attempts at blood gas sampling. A resultant blood gas sample showed an acceptable Po2 outside the criteria for recommending in-flight oxygen and a reduced Pco2. Entering the nadir Spo2 value into the Severinghaus equation gives an estimated arterial Po2 of 6 kPa (45 mmHg), which was felt to be more representative of resting values during HCT, and in-flight oxygen was recommended. While hyperventilation is an expected response to hypoxia, transient rises in Spo2 coinciding with threat of injury are likely to be attributable to emotional stress-induced hyperventilation, characteristic of B-I-I specific phobia and expected during the anticipation of exteroceptive threat, even in normal subjects. In summary, should excessive hyperventilation be detected during HCT and coincide with transient increases in Spo2, HCT should be repeated using Spo2 only as a guide to the level of hypoxemia, and Spo2 maintained using supplementary oxygen in accordance with alternative methods described in guidelines.Spurling KJ, McGoldrick VP. Blood-injection-injury (B-I-I) specific phobia affects the outcome of hypoxic challenge testing. Aerosp Med Hum Perform. 2017; 88(5):503-506.

Serum immunoreactive erythropoietin in high altitude natives with and without excessive erythrocytosis.

PubMed

León-Velarde, F; Monge, C C; Vidal, A; Carcagno, M; Criscuolo, M; Bozzini, C E

1991-05-01

We report the estimation of blood hemoglobin (Hb), arterial blood oxygen saturation (SaO2), and serum immunoreactive erythropoietin (siEPO) in a group of Peruvian workers residing in Cerro de Pasco at 4300 m showing "excessive erythrocytosis" (EE, Monge's disease, chronic mountain sickness). These estimates were compared with those of humans residing either in Cerro de Pasco and showing "normal erythrocytosis" (NE) or in Lima (sea level, SL) to determine whether Hb and SaO2 are related to siEPO in high altitude (HA) natives with NE or EE. The three parameters showed statistically significant differences between HA and SL groups--the values in SL being lower. Significant differences were also found between NE and EE groups in Hb and SaO2. There was no statistical difference in siEPo between the two groups. The results indicate, therefore, that HA residents who develop EE are not distinguishable from residents who develop NE on the basis of estimates of siEPO. As a result, siEPO and Hb do not show a dose-response relationship in HA residents, and variation in EPO does not explain the striking variation in Hb at high altitudes.

Realgar bioleaching solution suppress ras excessive activation by increasing ROS in Caenorhabditis elegans.

PubMed

Zhi, De Juan; Feng, Na; Liu, Dong Ling; Hou, Rong Li; Wang, Mei Zu; Ding, Xiao Xia; Li, Hong Yu

2014-03-01

Although realgar bioleaching solution (RBS) has been proved to be a potential candidate for cancer therapy, the mechanisms of RBS anticancer are still far from being completely understood. Dosed with RBS in C. elegans, the multivulva phenotype resulting from oncogenic ras gain-of-function was inhibited in a dose dependent manner. It could be abrogated by concurrent treatment C. elegans with RBS and the radical scavenger DMSO. However, RBS could not induce DAF-16 nuclear translocation in TJ356 or the increase of HSP 16.2 expression in CL2070, which both could be aroused visible GFP fluorescent variation to represent for oxidative stress generation. Treatment C. elegans with superoxide anion generator paraquat, similar results were also obtained. Our results indicated that RBS suppress excessive activated ras by increasing reactive oxygen species (ROS) in C. elegans. Secondly, ROS induced by RBS significantly accumulated on a higher level in C. elegans with a mutational ras than that with wild ras, thus leading to oxidative stress on ras gain-of-function background rather than on normal ras context. Our results firstly demonstrated that using C. elegans as a model organism for evaluating prooxidant drug candidates for cancer therapy.

Gankyrin has an antioxidative role through the feedback regulation of Nrf2 in hepatocellular carcinoma

PubMed Central

Yang, Chun; Tan, Ye-xiong; Yang, Guang-zhen; Zhang, Jian; Pan, Yu-fei; Liu, Chen; Fu, Jing; Chen, Yao; Ding, Zhi-wen

2016-01-01

Oxidative stress status has a key role in hepatocellular carcinoma (HCC) development and progression. Normally, reactive oxygen species (ROS) levels are tightly controlled by an inducible antioxidant program that responds to cellular stressors. How HCC cells respond to excessive oxidative stress remains elusive. Here, we identified a feedback loop between gankyrin, an oncoprotein overexpressed in human HCC, and Nrf2 maintaining the homeostasis in HCC cells. Mechanistically, gankyrin was found to interact with the Kelch domain of Keap1 and effectively competed with Nrf2 for Keap1 binding. Increased expression of gankyrin in HCC cells blocked the binding between Nrf2 and Keap1, inhibiting the degradation of Nrf2 by proteasome. Interestingly, accumulation and translocation of Nrf2 increased the transcription of gankyrin through binding to the ARE elements in the promoter of gankyrin. The positive feedback regulation involving gankyrin and Nrf2 modulates a series of antioxidant enzymes, thereby lowering intracellular ROS and conferring a steadier intracellular environment, which prevents mitochondrial damage and cell death induced by excessive oxidative stress. Our results indicate that gankyrin is a regulator of cellular redox homeostasis and provide a link between oxidative stress and the development of HCC. PMID:27091842

Targeting the NO/superoxide ratio in adipose tissue: relevance to obesity and diabetes management.

PubMed

Jankovic, Aleksandra; Korac, Aleksandra; Buzadzic, Biljana; Stancic, Ana; Otasevic, Vesna; Ferdinandy, Péter; Daiber, Andreas; Korac, Bato

2017-06-01

Insulin sensitivity and metabolic homeostasis depend on the capacity of adipose tissue to take up and utilize excess glucose and fatty acids. The key aspects that determine the fuel-buffering capacity of adipose tissue depend on the physiological levels of the small redox molecule, nitric oxide (NO). In addition to impairment of NO synthesis, excessive formation of the superoxide anion (О 2 •- ) in adipose tissue may be an important interfering factor diverting the signalling of NO and other reactive oxygen and nitrogen species in obesity, resulting in metabolic dysfunction of adipose tissue over time. Besides its role in relief from superoxide burst, enhanced NO signalling may be responsible for the therapeutic benefits of different superoxide dismutase mimetics, in obesity and experimental diabetes models. This review summarizes the role of NO in adipose tissue and highlights the effects of NO/О 2 •- ratio 'teetering' as a promising pharmacological target in the metabolic syndrome. This article is part of a themed section on Redox Biology and Oxidative Stress in Health and Disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.12/issuetoc. © 2016 The British Pharmacological Society.

Pathogenic implications of iron accumulation in multiple sclerosis

PubMed Central

Williams, Rachel; Buchheit, Cassandra L.; Berman, Nancy E. J.; LeVine, Steven M.

2011-01-01

Iron, an essential element used for a multitude of biochemical reactions, abnormally accumulates in the central nervous system of patients with multiple sclerosis (MS). The mechanisms of abnormal iron deposition in MS are not fully understood, nor do we know whether these deposits have adverse consequences, i.e., contribute to pathogenesis. With some exceptions, excess levels of iron are represented concomitantly in multiple deep gray matter structures often with bilateral representation, while in white matter pathological iron deposits are usually located at sites of inflammation that are associated with veins. These distinct spatial patterns suggest disparate mechanisms of iron accumulation between these regions. Iron has been postulated to promote disease activity in MS by various means: 1) iron can amplify the activated state of microglia resulting in the increased production of proinflammatory mediators; 2) excess intracellular iron deposits could promote mitochondria dysfunction; and 3) improperly managed iron could catalyze the production of damaging reactive oxygen species. The pathological consequences of abnormal iron deposits may be dependent on the affected brain region and/or accumulation process. Here we review putative mechanisms of enhanced iron uptake in MS and address the likely roles of iron in the pathogenesis of this disease. PMID:22004421

Effect of 3-keto-1,5-bisphosphonates on obese-liver's rats.

PubMed

Lahbib, Karima; Touil, Soufiane

2016-10-01

Obesity is associated with an oxidative stress status, which is defined by an excess of reactive oxygen species (ROS) vs. the antioxidant defense system. We report in this present work, the link between fat deposition and oxidative stress markers using a High Fat Diet-(HFD) induced rat obesity and liver-oxidative stress. We further determined the impact of chronic administration of 3-keto-1, 5-BPs 1 (a & b) (40μg/kg/8 weeks/i.p.) on liver's level. In fact, exposure of rats to HFD during 16 weeks induced body and liver weight gain and metabolic disruption with an increase on liver Alanine amino transférase (ALAT) and Aspartate aminotransférase (ASAT) concentration. HFD increased liver calcium level as well as free iron, whereas, it provoked a decrease on liver lipase activity. HFD also induced liver-oxidative stress status vocalized by an increase in reactive oxygen species (ROS) as superoxide radical (O 2 ), hydroxyl radical (OH) and Hydrogen peroxide (H 2 O 2 ). Consequently, different deleterious damages as an increase on Malon Dialdehyde MDA, Carbonyl protein PC levels with a decrease in non-protein sulfhydryls NPSH concentrations, have been detected. Interestingly, our results demonstrate a decrease in antioxidant enzymes activities such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidases (GPx) and peroxidases (POD). Importantly, 3-keto-1,5-bisphosphonates treatment corrected the majority of the deleterious effects caused by HFD, but it failed to correct some liver's disruptions as mineral profile, oxidative damages (PC and NPSH levels) as well as SOD and lipase activities. Our investigation point that 3-keto-1,5-bisphosphonates could be considered as safe antioxidant agents on the hepatic level that should also find other potential biological applications. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Preflight studies on tolerance of pocket mice to oxygen and heat. I - Physiological studies

NASA Technical Reports Server (NTRS)

Leon, H. A.; Suri, K.; Mctigue, M.; Smith, J.; Cooper, W.; Miquel, J.; Ashley, W. W.; Behnke, A. R., Jr.; Saunders, J. F.

1975-01-01

Tests were carried out on pocket mice to ascertain their tolerance to elevated oxygen pressures alone and to a combination of hyperoxia and heat in excess of that expected during the flight of the mice on Apollo XVII. The mice withstood oxygen partial pressures up to 12 psi at normal room temperature (24 C, 75 F) over a period of 7 days. A few mice previously exposed to increased PO2 died in the course of exposure to an oxygen pressure of 10 psi or 12 psi (517 mm or 620 mm Hg) for 13 d in ambient heat of 32 C (90 F). Supplemental vitamin E and physiological saline loading given prior to exposure had no apparent protective effect. The overall conclusion was that the pocket mice which were to go on Apollo XVII could readily survive the ambient atmosphere to which they would be exposed.

The Study of Micro-Pressure Inner-Loop Bioreactor Oxygen Mass Transfer Characteristics

NASA Astrophysics Data System (ADS)

Wan, L. G.; Lin, Q.; Bian, D. J.; Ren, Q. K.; Xiao, Y. B.; Lu, W. X.

2018-03-01

The oxygen mass transfer characteristics in a Micro-Pressure Inner-Loop bioreactor (MPR) were studied by clean water oxygenation experiment, the results show that when the aeration adopt by 0.1, 0.2, 0.4, 0.6 m3·h-1, respectively, the oxygen mass transfer coefficient KLa(20) in the reactor increases with the increase of the aeration. KLa(20) shows a good linear correlation with the aeration. The rate is 0.2128 h·m-3·min-1 and the correlation coefficient R=0.993. However, the trend of EO2 increases first and then decreases with the increase of aeration. When the aeration increased to 0.4 m3·h-1, the EO2 reaches the maximum. If aeration increases constantly, EO2 begin to decrease excessive aeration may lead to an increase in energy waste during reactor operation.

Ultimate intrinsic-coercivity samarium-cobalt magnet: An Earth-based feasibility study for space-shuttle missions. [containerless melts

NASA Technical Reports Server (NTRS)

Das, D. K.; Kumar, K.; Frost, R. T.; Chang, C. W.

1980-01-01

Techniques for containerless melting and solidification of the samarium-cobalt alloy without excessive oxidation were developed. The rationale for extending these experiments in a weightless environment is also discussed. The effect of oxygen content from 0.15 to 0.63 weight percent and grain size in the range of 2 to 10 micrometers has been examined on arc-plasma-sprayed SmCo5 magnets. Contrary to expectations, the larger grain sizes tended to improve the coercivities. This was attributed to an increase in homogeneity resulting from higher temperature treatments used to produce larger grain size. No significant differences in coercivity were observed on the basis of oxygen content in the range examined. It is expected that more meaningful data on the relationship between oxygen content and coercivity will be seen when the oxygen content can be lowered to less than 0.1 weight percent.

Mitigating oxygen loss to improve the cycling performance of high capacity cation-disordered cathode materials

DOE PAGES

Lee, Jinhyuk; Papp, Joseph K.; Clément, Raphaële J.; ...

2017-10-17

Recent progress in the understanding of percolation theory points to cation-disordered lithium-excess transition metal oxides as high-capacity lithium-ion cathode materials. Nevertheless, the oxygen redox processes required for these materials to deliver high capacity can trigger oxygen loss, which leads to the formation of resistive surface layers on the cathode particles. Here, we demonstrate here that, somewhat surprisingly, fluorine can be incorporated into the bulk of disordered lithium nickel titanium molybdenum oxides using a standard solid-state method to increase the nickel content, and that this compositional modification is very effective in reducing oxygen loss, improving energy density, average voltage, and ratemore » performance. We argue that the valence reduction on the anion site, offered by fluorine incorporation, opens up significant opportunities for the design of high-capacity cation-disordered cathode materials.« less

Molecular demultiplexer as a terminator automaton.

PubMed

Turan, Ilke S; Gunaydin, Gurcan; Ayan, Seylan; Akkaya, Engin U

2018-02-23

Molecular logic gates are expected to play an important role on the way to information processing therapeutic agents, especially considering the wide variety of physical and chemical responses that they can elicit in response to the inputs applied. Here, we show that a 1:2 demultiplexer based on a Zn 2+ -terpyridine-Bodipy conjugate with a quenched fluorescent emission, is efficient in photosensitized singlet oxygen generation as inferred from trap compound experiments and cell culture data. However, once the singlet oxygen generated by photosensitization triggers apoptotic response, the Zn 2+ complex then interacts with the exposed phosphatidylserine lipids in the external leaflet of the membrane bilayer, autonomously switching off singlet oxygen generation, and simultaneously switching on a bright emission response. This is the confirmatory signal of the cancer cell death by the action of molecular automaton and the confinement of unintended damage by excessive singlet oxygen production.

Mitigating oxygen loss to improve the cycling performance of high capacity cation-disordered cathode materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Jinhyuk; Papp, Joseph K.; Clément, Raphaële J.

Recent progress in the understanding of percolation theory points to cation-disordered lithium-excess transition metal oxides as high-capacity lithium-ion cathode materials. Nevertheless, the oxygen redox processes required for these materials to deliver high capacity can trigger oxygen loss, which leads to the formation of resistive surface layers on the cathode particles. Here, we demonstrate here that, somewhat surprisingly, fluorine can be incorporated into the bulk of disordered lithium nickel titanium molybdenum oxides using a standard solid-state method to increase the nickel content, and that this compositional modification is very effective in reducing oxygen loss, improving energy density, average voltage, and ratemore » performance. We argue that the valence reduction on the anion site, offered by fluorine incorporation, opens up significant opportunities for the design of high-capacity cation-disordered cathode materials.« less

Chain Reaction: A Detailed look at Reactive Nitrogen and Possible Management Approaches

EPA Science Inventory

Nitrogen is one of the building blocks of life, yet excessive amounts in the environment can cause problems in various ecosystems. Abundant in the atmosphere as dinitrogen (N₂), nitrogen needs to be combined with other elements such as hydrogen or oxygen to...

Metals, Metallothioneins and Oxidative Stress in Blood of Autistic Children

ERIC Educational Resources Information Center

Vergani, Laura; Cristina, Lanza; Paola, Rivaro; Luisa, Abelmoschi M.; Shyti, Genti; Edvige, Veneselli; Giuseppe, Minniti; Elena, Grasselli; Laura, Canesi; Adriana, Voci

2011-01-01

Many factors have been implicated in autism onset, including excess or deficiency in toxic or essential metals and impaired antioxidant systems. Protection towards the damaging effects of reactive oxygen species (ROS) is afforded by antioxidant enzymes (superoxide dismutase, SOD, catalase, CAT, glutathione peroxidase, GPx), and non-enzymatic…

Serum metabolites from walnut-fed aged rats attenuate stress-induced neurotoxicity in brain cells in vitro

USDA-ARS?s Scientific Manuscript database

The shift in equilibrium towards excess reactive oxygen or nitrogen species production from innate antioxidant defense in brain is a critical factor in the declining neural functions and cognitive deficits accompanying age. In aging, there are noticeable alterations in the membrane microenvironment,...

40 CFR 60.4248 - What definitions apply to this subpart?

Code of Federal Regulations, 2010 CFR

2010-07-01

... is designed to properly function in terms of reliability and fuel consumption, without being... Earth's surface that maintains a gaseous state at standard atmospheric temperature and pressure under... rich burn engine if the excess oxygen content of the exhaust at full load conditions is less than or...

40 CFR 60.4248 - What definitions apply to this subpart?

Code of Federal Regulations, 2011 CFR

2011-07-01

... is designed to properly function in terms of reliability and fuel consumption, without being... Earth's surface that maintains a gaseous state at standard atmospheric temperature and pressure under... rich burn engine if the excess oxygen content of the exhaust at full load conditions is less than or...

40 CFR 60.4248 - What definitions apply to this subpart?

Code of Federal Regulations, 2014 CFR

2014-07-01

... is designed to properly function in terms of reliability and fuel consumption, without being... a gaseous state at standard atmospheric temperature and pressure under ordinary conditions, and... the excess oxygen content of the exhaust at full load conditions is less than or equal to 2 percent...

40 CFR 60.4248 - What definitions apply to this subpart?

Code of Federal Regulations, 2012 CFR

2012-07-01

... is designed to properly function in terms of reliability and fuel consumption, without being... gaseous state at standard atmospheric temperature and pressure under ordinary conditions, and which is... recommendations regarding air/fuel ratio will be considered a rich burn engine if the excess oxygen content of the...

40 CFR 60.4248 - What definitions apply to this subpart?

Code of Federal Regulations, 2013 CFR

2013-07-01

... is designed to properly function in terms of reliability and fuel consumption, without being... a gaseous state at standard atmospheric temperature and pressure under ordinary conditions, and... the excess oxygen content of the exhaust at full load conditions is less than or equal to 2 percent...

Mechanism of Cyclic Dye Regeneration During Eosin-Sensitized Photoinitiation in the Presence of Polymerization Inhibitors

PubMed Central

Avens, Heather J.; Bowman, Christopher N.

2009-01-01

A visible light photoinitiator, eosin, in combination with a tertiary amine coinitiator is found to initiate polymerization despite the presence of at least 1000-fold excess dissolved oxygen which functions as an inhibitor of radical polymerizations. Additionally, 0.4 µM eosin is able to overcome 100-fold excess (40 µM) 2,2,6,6-Tetramethyl-1-piperidinyloxy (TEMPO) inhibitor, initiating polymerization after only a 2 minute inhibition period. In contrast, 40 µM Irgacure-2959, a standard cleavage-type initiator, is unable to overcome even an equivalent amount of inhibitor (40 µM TEMPO). Through additional comparisons of these two initiation systems, a reaction mechanism is developed which is consistent with the kinetic data and provides an explanation for eosin’s relative insensitivity to oxygen, TEMPO and other inhibitors. A cyclic mechanism is proposed in which semi-reduced eosin radicals react by disproportionation with radical inhibitors and radical intermediates in the inhibition process to regenerate eosin and effectively consume inhibitor. In behavior similar to that of eosin, rose bengal, fluorescein, and riboflavin are also found to initiate polymerization despite the presence of excess TEMPO, indicating that cyclic regeneration likely enhances the photoinitiation kinetics of many dye photosensitizers. Selection of such dye initiation systems constitutes a valuable strategy for alleviating inhibitory effects in radical polymerizations. PMID:20098667

Triiodothyronine, beta-adrenergic receptors, agonist responses, and exercise capacity.

PubMed

Martin, W H

1993-07-01

Although thyroid hormone excess results in increased beta-adrenergic receptor density or agonist responses in some cells of experimental animals, the role of these effects in contributing to clinical manifestations of hyperthyroidism in human subjects is unclear. To shed further light on this issue, we characterized the effect of 2 weeks of excess triiodothyronine administration on cardiac and metabolic responses to graded-dose isoproterenol infusion, skeletal muscle beta-adrenergic receptor density, and physiologic determinants of exercise capacity in young healthy subjects. The slope of the heart rate response to isoproterenol was 36% greater (p < 0.05) after triiodothyronine administration. In addition, beta-adrenergic receptor density was increased (p < 0.01) in all types of skeletal muscle fibers. Maximal oxygen uptake during treadmill exercise declined 5% (p < 0.001) after triiodothyronine administration because of a decrease in the arteriovenous oxygen difference (p < 0.05). The plasma lactate response to submaximal exercise was 25% greater (p < 0.01) in the hyperthyroid state. These effects were paralleled by a decrement in skeletal muscle oxidative capacity and a decrease in cross-sectional area of type 2A skeletal myocytes. Thus, thyroid hormone excess enhances cardiac beta-adrenergic sensitivity under in vivo conditions in human subjects. Nevertheless, exercise capacity is diminished in the hyperthyroid state, an effect that may be related to reduced skeletal muscle oxidative capacity and type 2A fiber atrophy.

In vitro measurements of oxygen consumption rates in hTERT-RPE cells exposed to low levels of red light

NASA Astrophysics Data System (ADS)

Wigle, Jeffrey C.; Castellanos, Cherry C.

2016-03-01

Exposure to 2.88 J/cm2 of red light induces an adaptive response against a lethal pulse of 2.0 μm laser radiation in hTERT-RPE cells in vitro, but not in a knockdown mutant for vascular endothelial growth factor c (VEGF-C). The generally accepted initiation sequence for photobiomodulation is that absorption of red light by cytochome c oxidase (CCOX) of the electron transport chain increases the binding affinity of CCOX for O2 vs. nitric oxide (NO). This results in displacement of NO by O2 in the active site of CCOX, thereby increasing cellular respiration and intracellular ATP. We've previously reported that red-light exposure induces a small, but consistently reproducible, increase in NO levels in these cells. But the relative importance of NO and oxidative phosphorylation is unclear because little is known about the relative contributions of NO and ATP to the response. However, if NO dissociation from CCOX actually increases oxidative phosphorylation, one should see a corresponding increase in oxygen consumption. A Seahorse Extracellular Flux Analyzer was used to measure oxygen consumption rates (OCR) in normal and mutant cells as a proxy for oxidative phosphorylation. Both basal respiration and maximum respiration rates in normal cells are significantly higher than in the mutant. The normal cells have a significant amount of "excess capacity," whereas the VEGF-C(KD) have little or none. The OCR in exposed normal cells is lower than in unexposed cells when measured immediately after exposure. The exposures used for these experiments had no effect on the OCR in mutant cells.

Microvascular Endothelial Dysfunction in Sedentary, Obese Humans is mediated by NADPH Oxidase; Influence of Exercise Training

PubMed Central

La Favor, Justin D.; Dubis, Gabriel S.; Yan, Huimin; White, Joseph D.; Nelson, Margaret A.M.; Anderson, Ethan J.; Hickner, Robert C.

2016-01-01

Objective The objectives of this study were to determine the impact of in vivo reactive oxygen species (ROS) on microvascular endothelial function in obese human subjects and to determine the efficacy of an aerobic exercise intervention on alleviating obesity-associated dysfunctionality. Approach and Results Young, sedentary men and women were divided into lean (BMI 18–25; n=14), intermediate (BMI 28–32.5; n=13), and obese (BMI 33–40; n=15) groups. A novel microdialysis technique was utilized to detect elevated interstitial hydrogen peroxide (H2O2) and superoxide levels in the vastus lateralis of obese compared to both lean and intermediate subjects. Nutritive blood flow was monitored in the vastus lateralis via the microdialysis-ethanol technique. A decrement in acetylcholine-stimulated blood flow revealed impaired microvascular endothelial function in the obese subjects. Perfusion of apocynin, an NADPH oxidase (Nox) inhibitor, lowered (normalized) H2O2 and superoxide levels and reversed microvascular endothelial dysfunction in obese subjects. Following 8-weeks of exercise, H2O2 levels were decreased in the obese subjects and microvascular endothelial function in these subjects was restored to levels similar to lean subjects. Skeletal muscle protein expression of the Nox subunits p22phox, p47phox, and p67phox were increased in obese relative to lean subjects, where p22phox and p67phox expression was attenuated by exercise training in obese subjects. Conclusions This study implicates Nox as a source of excessive ROS production in skeletal muscle of obese individuals, and links excessive Nox derived ROS to microvascular endothelial dysfunction in obesity. Furthermore, aerobic exercise training proved to be an effective strategy for alleviating these maladies. PMID:27765769

Geochemical studies of fluoride and other water quality parameters of ground water in Dhule region Maharashtra, India.

PubMed

Patil, Dilip A; Deshmukh, Prashant K; Fursule, Ravindra A; Patil, Pravin O

2010-07-01

This study has been carried out to find out the water pollutants and to test the suitability of water for drinking and irrigation purposes in Dhule and surrounding areas in Maharashtra State in India. The analysis was carried out for the parameters pH, DO (dissolved oxygen), BOD (biological oxygen demand), Cl-, NO3-, F-, S(2)-, total alkalinity, total solid, total dissolved solids (TDS), total suspended solids (TSS), total hardness, calcium, magnesium, carbonate and noncarbonate hardness, and concentrations of calcium and magnesium. These parameters were compared against the standards laid down by World Health Organization (WHO) and Indian Council of Medical Research (ICMR) for drinking water quality. High levels of NO(3)-, Cl-, F-, S(2)-, total solid, TDS, TSS, total hardness, magnesium and calcium have been found in the collected samples. From these observations, it has been found that fluoride is present as per the permissible limit (WHO 2003) in some of the villages studied, but both fluoride and nitrate levels are unacceptable in drinking water samples taken from several villages in Dhule. This is a serious problem and, therefore, requires immediate attention. Excess of theses impurities in water causes many diseases in plants and animals. This study has been carried out to find out the water pollutants and to test the suitability of water for drinking and irrigation purposes in Dhule and surrounding areas in Maharashtra.

Sterilization of medical devices by ethylene oxide, determination of the dissipation of residues, and use of Green Fluorescent Protein as an indicator of process control.

PubMed

Dias, Fábio N; Ishii, Marina; Nogaroto, Sergio L; Piccini, Bruno; Penna, Thereza C V

2009-11-01

Ethylene oxide (EO) is used to sterilize Oxygenator and Tubing applied to heart surgery. Residual levels of EO and its derivatives, ethylene chlorohydrin (ECH) and ethylene glycol (EG), may be hazardous to the patients. Therefore, it must be removed by the aeration process. This study aimed to estimate the minimum aeration time for these devices to attain safe limits for use (avoiding excessive aeration time) and to evaluate the Green Fluorescent Protein (GFP) as a biosensor capable of best indicating the distribution and penetration of EO gas throughout the sterilization chamber. Sterilization cycles of 2, 4, and 8 h were monitored by Bacillus atrophaeus ATCC 9372 as a biological indicator (BI) and by the GFP. Residual levels of EO, ECH, and EG were determined by gas chromatography (GC), and the residual dissipation was studied. Safe limits were reached right after the sterilization process for Oxygenator and after 204 h of aeration for Tubing. In the 2 h cycle, the GFP concentration decreased from 4.8 (+/-3.2)% to 7.5 (+/-2.5)%. For the 4 h cycle, the GFP concentration decreased from 17.4 (+/-3.0)% to 21.5 (+/-6.8)%, and in the 8 h cycle, it decreased from 22.5 (+/-3.2)% to 23.9 (+/-3.9)%. This finding showed the potentiality for GFP applications as an EO biosensor.

The distributions of, and relationship between, 3He and nitrate in eddies

NASA Astrophysics Data System (ADS)

Jenkins, W. J.; McGillicuddy, D. J., Jr.; Lott, D. E., III

2008-05-01

We present and discuss the distribution of 3He and its relationship to nutrients in two eddies (cyclone C1 and anticyclone A4) with a view towards examining eddy-related mechanisms whereby nutrients are transported from the upper 200-300 m into the euphotic zone of the Sargasso Sea. The different behavior of these tracers in the euphotic zone results in changes in their distributions and relationships that may provide important clues as to the nature of physical and biological processes involved. The cyclonic eddy (C1) is characterized by substantial 3He excesses within the euphotic zone. The distribution of this excess 3He is strongly suggestive of both past and recent ongoing deep-water injection into the euphotic zone. Crude mass balance calculations suggest that an average of approximately 1.4±0.7 mol m -2 of nitrate has been introduced into the euphotic zone of eddy C1, consistent with the integrated apparent oxygen utilization anomaly in the aphotic zone below. The 3He-NO 3 relationship within the eddy deviates substantially from the linear thermocline trend, suggestive of incomplete drawdown of nutrients and/or substantial mixing between euphotic and aphotic zone waters. Anticyclone (A4) displays a simpler 3He-NO 3 relationship, but is relatively impoverished in euphotic zone excess 3He. We suggest that because of the relatively strong upwelling and lateral divergence of water the residence time of upwelled 3He is relatively short within the euphotic zone of this eddy. An estimate of the recently upwelled nutrient inventory, based on the excess 3He observed in A4's lower euphotic zone, is stoichiometrically consistent with the oxygen maximum observed in the euphotic zone.

The BLI-3/TSP-15/DOXA-1 Dual Oxidase Complex Is Required for Iodide Toxicity in Caenorhabditis elegans

PubMed Central

Xu, Zhaofa; Luo, Jintao; Li, Yu; Ma, Long

2014-01-01

Iodine is an essential trace element for life. Iodide deficiency can lead to defective biosynthesis of thyroid hormones and is a major cause of hypothyroidism and mental retardation. Excess iodide intake, however, has been linked to different thyroidal diseases. How excess iodide causes harmful effects is not well understood. Here, we found that the nematode Caenorhabditis elegans exhibits developmental arrest and other pleiotropic defects when exposed to excess iodide. To identify the responsible genes, we performed a forward genetic screen and isolated 12 mutants that can survive in excess iodide. These mutants define at least four genes, two of which we identified as bli-3 and tsp-15. bli-3 encodes the C. elegans ortholog of the mammalian dual oxidase DUOX1 and tsp-15 encodes the tetraspanin protein TSP-15, which was previously shown to interact with BLI-3. The C. elegans dual oxidase maturation factor DOXA-1 is also required for the arresting effect of excess iodide. Finally, we detected a dramatically increased biogenesis of reactive oxygen species in animals treated with excess iodide, and this effect can be partially suppressed by bli-3 and tsp-15 mutations. We propose that the BLI-3/TSP-15/DOXA-1 dual oxidase complex is required for the toxic pleiotropic effects of excess iodide. PMID:25480962

Protein S-nitrosylation as a therapeutic target for neurodegenerative diseases

PubMed Central

Nakamura, Tomohiro; Lipton, Stuart A.

2015-01-01

At physiological levels, nitric oxide (NO) contributes to the maintenance of normal neuronal activity and survival, thus serving as an important regulatory mechanism in the central nervous system. In contrast, accumulating evidence suggests that exposure to environmental toxins or the normal aging process can trigger excessive production of reactive oxygen/nitrogen species (such as NO), contributing to the etiology of several neurodegenerative diseases. Here we highlight protein S-nitrosylation, resulting from covalent attachment of an NO group to a cysteine thiol of the target protein, as a ubiquitous effector of NO signaling in both health and disease. We review our current understanding of this redox-dependent posttranslational modification under neurodegenerative conditions, and evaluate how targeting dysregulated protein S-nitrosylation can lead to novel therapeutics. PMID:26707925

Cross talk between increased intracellular zinc (Zn2+) and accumulation of reactive oxygen species in chemical ischemia.

PubMed

Slepchenko, Kira G; Lu, Qiping; Li, Yang V

2017-10-01

Both zinc (Zn 2+ ) and reactive oxygen species (ROS) have been shown to accumulate during hypoxic-ischemic stress and play important roles in pathological processes. To understand the cross talk between the two of them, here we studied Zn 2+ and ROS accumulation by employing fluorescent probes in HeLa cells to further the understanding of the cause and effect relationship of these two important cellular signaling systems during chemical-ischemia, stimulated by oxygen and glucose deprivation (OGD). We observed two Zn 2+ rises that were divided into four phases in the course of 30 min of OGD. The first Zn 2+ rise was a transient, which was followed by a latent phase during which Zn 2+ levels recovered; however, levels remained above a basal level in most cells. The final phase was the second Zn 2+ rise, which reached a sustained plateau called Zn 2+ overload. Zn 2+ rises were not observed when Zn 2+ was removed by TPEN (a Zn 2+ chelator) or thapsigargin (depleting Zn 2+ from intracellular stores) treatment, indicating that Zn 2+ was from intracellular storage. Damaging mitochondria with FCCP significantly reduced the second Zn 2+ rise, indicating that the mitochondrial Zn 2+ accumulation contributes to Zn 2+ overload. We also detected two OGD-induced ROS rises. Two Zn 2+ rises preceded two ROS rises. Removal of Zn 2+ reduced or delayed OGD- and FCCP-induced ROS generation, indicating that Zn 2+ contributes to mitochondrial ROS generation. There was a Zn 2+ -induced increase in the functional component of NADPH oxidase, p47 phox , thus suggesting that NADPH oxidase may mediate Zn 2+ -induced ROS accumulation. We suggest a new mechanism of cross talk between Zn 2+ and mitochondrial ROS through positive feedback processes that eventually causes excessive free Zn 2+ and ROS accumulations during the course of ischemic stress. Copyright © 2017 the American Physiological Society.

Reactive oxygen metabolites (ROMs) as an index of oxidative stress in obstructive sleep apnea patients.

PubMed

Christou, Kostas; Markoulis, Nikolaos; Moulas, Anargyros N; Pastaka, Chaido; Gourgoulianis, Kostantinos I

2003-09-01

Obstructive sleep apnea syndrome (OSA) is accompanied by oxygen desaturation and arousal from sleep. Free oxygen radicals are highly reactive molecules which could be produced by the OSA phenomenon of hypoxia/reoxygenation: cyclical alterations of arterial oxygen saturation with oxygen desaturation developing in response to apneas followed by resumption of oxygen saturation during hyperventilation. On the basis of these considerations, it was hypothesized that OSA may be linked to increased oxidative stress. Twenty-six participants gave an interview during which a physician asked them about their age, smoking habits, and symptoms such as excessive daytime sleepiness and snoring. Physical examination and polysomnography were performed during their hospitalization. Reactive oxygen metabolites (ROMs) were measured in blood samples by the diacron reactive oxygen metabolites (D-ROM) test. Twenty-one out of 26 subjects had an apnea/hypopnea index greater than 5 (OSA group). The measurement of free radicals was high in OSA patients. Furthermore, ROMs values in OSA patients were linearly correlated with the apnea/hypopnea index (R = 0.426; p = 0.042). The predictive value of a positive D-ROM test is 81%. ROMs were elevated in patients with OSA. When OSA was severe, similarly the value of ROMs in blood samples was enhanced, and the probable underlying mechanism for these events is the hypoxia/reoxygenation phenomenon.

Perovskite-related LaTiO3.41.

PubMed

Daniels, Peter; Lichtenberg, Frank; van Smaalen, Sander

2003-02-01

Crystals of pentalanthanum pentatitanium heptadecaoxide (La(5)Ti(5)O(17) with 0.3% oxygen excess, or LaTiO(3.41)) have been synthesized by floating-zone melting, and the structure has been solved using single-crystal X-ray diffraction intensities. The monoclinic (P2(1)/c) structure consists of perovskite-like slabs of vertex-sharing TiO(6) octahedra, which are separated by additional oxygen layers. The slabs are five octahedra wide. Due to the adjustment of the TiO(6) octahedra to meet the coordination requirements of the La(3+) cations, a superstructure develops along the a axis.

Is Lake Chabot Eutrophic?

NASA Astrophysics Data System (ADS)

Pellegrini, K.; Logan, J.; Esterlis, P.; Lew, A.; Nguyen, M.

2013-12-01

Introduction/Abstract: Lake Chabot is an integral part of the East Bay watershed that provides habitats for animals and recreation for humans year-round. Lake Chabot has been in danger of eutrophication due to excessive dumping of phosphorous and nitrogen into the water from the fertilizers of nearby golf courses and neighboring houses. If the lake turned out to be eutrophified, it could seriously impact what is currently the standby emergency water supply for many Castro Valley residents. Eutrophication is the excessive richness of nutrients such as nitrogen and phosphorus in a lake, usually as a result of runoff. This buildup of nutrients causes algal blooms. The algae uses up most of the oxygen in the water, and when it dies, it causes the lake to hypoxify. The fish in the lake can't breathe, and consequently suffocate. Other oxygen-dependant aquatic creatures die off as well. Needless to say, the eutrophication of a lake is bad news for the wildlife that lives in or around it. The level of eutrophication in our area in Northern California tends to increase during the late spring/early summer months, so our crew went out and took samples of Lake Chabot on June 2. We focused on the area of the lake where the water enters, known on the map as Honker Bay. We also took readings a ways down in deeper water for comparison's sake. Visually, the lake looked in bad shape. The water was a murky green that glimmered with particulate matter that swirled around the boat as we went by. In the Honker Bay region where we focused our testing, there were reeds bathed in algae that coated the surface of the lake in thick, swirling patterns. Surprisingly enough, however, our test results didn't reveal any extreme levels of phosphorous or nitrogen. They were slightly higher than usual, but not by any significant amount. The levels we found were high enough to stimulate plant and algae growth and promote eutrophication, but not enough to do any severe damage. After a briefing with a veteran member of the East Bay Regional Park District, Hal MacLean, we realized that almost every lake goes through periods of slight eutrophication. Actually, this phenomenon of waxing and waning of nutrient levels is something many species have grown accustomed too. It's just the extreme cases where the water is actively being polluted by a nearby point source that cause so much damage. Overall, despite outward appearances, the lake is relatively healthy. It boasts high biodiversity in and around the lake, housing such species as dragonflies, eucalyptus, bald eagles, halibut, bass, and even tiny silver goldfish. It fluctuates in oxygen and nutrient content just like any other lake, but for now, it isn't cause for too much concern. It's a beloved element of the Castro Valley community and we hope it will remain so for many generations to come.

Oxygen as a factor in eukaryote evolution - Some effects of low levels of oxygen on Saccharomyces cerevisiae

NASA Technical Reports Server (NTRS)

Jahnke, L.; Klein, H. P.

1979-01-01

A comparative study of the effects of varying levels of oxygen on some of the metabolic functions of the primitive eukaryote, Saccharomyces cerevisiae, has shown that these cells are responsive to very low levels of oxygen: the level of palmitoyl-Co A desaturase was greatly enhanced by only 0.03 vol % oxygen. Similarly, an acetyl-CoA synthetase associated predominantly with anaerobic growth was stimulated by as little as 0.1% oxygen, while an isoenzyme correlated with aerobic growth was maximally active at much higher oxygen levels (greater than 1%). Closely following this latter pattern were three mitochondrial enzymes that attained maximal activity only under atmospheric levels of oxygen.

Plasma Free Hemoglobin Generation Using the EOS PMP™ Oxygenator and the CentriMag® Blood Pump.

PubMed

Hodge, Ashley B; Deitemyer, Matthew A; Duffy, Victoria L; Tumin, Dmitry; Garbin, Dorothy A; Nicol, Kathleen K; Hayes, Don; Cismowski, Mary J; Yates, Andrew R

2018-06-01

Hemolysis is a known consequence of extracorporeal membrane oxygenation (ECMO) resulting from shear force within the different components of the extracorporeal circuit. The primary aim of this study was to evaluate the EOS PMP ™ oxygenator for generation of plasma free hemoglobin (PfHg) over 24 hours at nominal operating range flow rates. The EOS ECMO ™ (LivaNova, Inc.; formerly Sorin, Arvada, CO) is equipped with a plasma tight polymethylpentene (PMP) hollow fiber oxygenator. We hypothesized that PfHg generation would be elevated in circuits with higher flow rates, because of the significant pressure drop across the oxygenator according to manufacturer provided flow charts. Generated PfHg concentrations were compared with PfHg concentrations from blood not exposed to an ECMO circuit. The secondary aim was to evaluate circuit flow-rate-induced changes in platelet count and platelet function over 24 hours. Circuits contained a CentriMag ® (St. Jude Medical, St. Paul, MN) blood pump and an EOS ECMO PMP ™ oxygenator. Circuits in triplicate were run continuously for 24 hours at three flow rates [1, 3, and 5 liters per minute {LPM}]. PfHg was analyzed at baseline, 6, 12, 18, and 24 hours. Platelet count and function were measured at baseline and 24 hours. Concentrations of PfHg at baseline for circuits operating at 1, 3, and 5 LPM were 24.4 ± 4.0, 38.4 ± 28.6, and 26.7 ± 6.9 mg/dL, respectively. PfHg concentrations after 24 hours were statistically compared for the three flow rates using analysis of variance; PfHg concentrations at 1 LPM (181.4 ± 29.1 mg/dL), 3 LPM (145.9 ± 8.7 mg/dL), and 5 LPM (100.1 ± 111.3 mg/dL) circuits. The F -test was not statistically significant ( p = .632), indicating that PfHg generation at 24 hours was similar among the three flow rates. Excessive hemolysis using PfHg levels in the EOS PMP ™ membrane oxygenator was not observed.

Method of producing thermally sprayed metallic coating

DOEpatents

Byrnes, Larry Edward [Rochester Hills, MI; Kramer, Martin Stephen [Clarkston, MI; Neiser, Richard A [Albuquerque, NM

2003-08-26

The cylinder walls of light metal engine blocks are thermally spray coated with a ferrous-based coating using an HVOF device. A ferrous-based wire is fed to the HVOF device to locate a tip end of the wire in a high temperature zone of the device. Jet flows of oxygen and gaseous fuel are fed to the high temperature zone and are combusted to generate heat to melt the tip end. The oxygen is oversupplied in relation to the gaseous fuel. The excess oxygen reacts with and burns a fraction of the ferrous-based feed wire in an exothermic reaction to generate substantial supplemental heat to the HVOF device. The molten/combusted metal is sprayed by the device onto the walls of the cylinder by the jet flow of gases.

Performance of dentrification beds for removing nitrate from drainage water at cold temperatures

USDA-ARS?s Scientific Manuscript database

Transport of soluble nitrogen and phosphorus to water bodies has been a concern for many years due to human health issues, and is a major contributor to the formation of oxygen deficiency in aquatic ecosystems. Agricultural subsurface drainage is one pathway for transport of excess nutrients to surf...

Catalyst for treatment and control of post-combustion emissions

NASA Technical Reports Server (NTRS)

Upchurch, legal representative, Wilhelmina H. (Inventor); Schryer, David R. (Inventor); Upchurch, Billy T. (Inventor)

2008-01-01

The present invention utilizes two precious metals with two to five different metal-oxides in a layered matrix to convert CO, HCs, and NOx to CO.sub.2, and N.sub.2 by oxidation of two components and reduction of the other in a moderately high temperature gaseous environment containing excess oxygen.

40 CFR 52.1977 - Content of approved State submitted implementation plan.

Code of Federal Regulations, 2013 CFR

2013-07-01

...) Division 28—Stationary Source Air Pollution Control and Permitting Procedures Excess Emissions and... Requirements (11/4/93) 28-1450Enforcement Action Criteria (9/24/93) Division 200—General Air Pollution... Designations (10/14/99) 204-0090Oxygenated Gasoline Control Areas (3/27/01) Division 206—Air Pollution...

40 CFR 52.1977 - Content of approved State submitted implementation plan.

Code of Federal Regulations, 2012 CFR

2012-07-01

...) Division 28—Stationary Source Air Pollution Control and Permitting Procedures Excess Emissions and... Requirements (11/4/93) 28-1450Enforcement Action Criteria (9/24/93) Division 200—General Air Pollution... Designations (10/14/99) 204-0090Oxygenated Gasoline Control Areas (3/27/01) Division 206—Air Pollution...

40 CFR 52.1977 - Content of approved State submitted implementation plan.

Code of Federal Regulations, 2014 CFR

2014-07-01

...) Division 28—Stationary Source Air Pollution Control and Permitting Procedures Excess Emissions and... Requirements (11/4/93) 28-1450Enforcement Action Criteria (9/24/93) Division 200—General Air Pollution... Designations (10/14/99) 204-0090Oxygenated Gasoline Control Areas (3/27/01) Division 206—Air Pollution...

40 CFR 52.1977 - Content of approved State submitted implementation plan.

Code of Federal Regulations, 2011 CFR

2011-07-01

...) Division 28—Stationary Source Air Pollution Control and Permitting Procedures Excess Emissions and... Requirements (11/4/93) 28-1450Enforcement Action Criteria (9/24/93) Division 200—General Air Pollution... Designations (10/14/99) 204-0090Oxygenated Gasoline Control Areas (3/27/01) Division 206—Air Pollution...

PHYSICAL AND BIOLOGICAL CONTROLS ON DISSOLVED OXYGEN DYNAMICS IN A NORTHEASTERN GULF OF MEXICO ESTUARY

EPA Science Inventory

Nutrient over-enrichment is one of the most often cited causes of 305b impairment in coastal waters. Excessive nutrients affect designated uses of the nation's aquatic resources, and pose risks to human health and the environment. The process of developing nutrient criteria for e...

Evidence for polyphosphate accumulating organism (PAO)-mediated phosphorus cycling in stream biofilms under alternating aerobic/anaerobic conditions

USDA-ARS?s Scientific Manuscript database

Phosphorus (P) is often a limiting nutrient in freshwater ecosystems and excessive inputs can lead to eutrophication. In-stream cycling of P involves complex biological, chemical, and physical processes that are not fully understood. Microbial metabolisms are suspected to control oxygen-dependent up...

Development of Aptitude at Altitude

ERIC Educational Resources Information Center

Hogan, Alexandra M.; Virues-Ortega, Javier; Botti, Ana Baya; Bucks, Romola; Holloway, John W.; Rose-Zerilli, Matthew J.; Palmer, Lyle J.; Webster, Rebecca J.; Baldeweg, Torsten; Kirkham, Fenella J.

2010-01-01

Millions of people currently live at altitudes in excess of 2500 metres, where oxygen supply is limited, but very little is known about the development of brain and behavioural function under such hypoxic conditions. We describe the physiological, cognitive and behavioural profile of a large cohort of infants (6-12 months), children (6-10 years)…

Serum metabolites from walnut-fed aged rats attenuate stress-induced neurotoxicity in BV-2 microglial cells

USDA-ARS?s Scientific Manuscript database

The shift in equilibrium towards excess reactive oxygen or nitrogen species production from innate antioxidant defenses in brain is a critical factor in the declining neural function and cognitive deficit accompanying age. Previous studies from our laboratory have reported that walnuts, rich in poly...

Reactive oxygen species (ROS) and cancer: Role of antioxidative nutraceuticals.

PubMed

Prasad, Sahdeo; Gupta, Subash C; Tyagi, Amit K

2017-02-28

Extensive research over the past half a century indicates that reactive oxygen species (ROS) play an important role in cancer. Although low levels of ROS can be beneficial, excessive accumulation can promote cancer. One characteristic of cancer cells that distinguishes them from normal cells is their ability to produce increased numbers of ROS and their increased dependence on an antioxidant defense system. ROS are produced as a byproduct intracellularly by mitochondria and other cellular elements and exogenously by pollutants, tobacco, smoke, drugs, xenobiotics, and radiation. ROS modulate various cell signaling pathways, which are primarily mediated through the transcription factors NF-κB and STAT3, hypoxia-inducible factor-1α, kinases, growth factors, cytokines and other proteins, and enzymes; these pathways have been linked to cellular transformation, inflammation, tumor survival, proliferation, invasion, angiogenesis, and metastasis of cancer. ROS are also associated with epigenetic changes in genes, which is helpful in diagnosing diseases. This review considers the role of ROS in the various stages of cancer development. Finally, we provide evidence that nutraceuticals derived from Mother Nature are highly effective in eliminating cancer cells. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Chlorogenic acid ameliorates alcohol-induced liver injuries through scavenging reactive oxygen species.

PubMed

Kim, Hyunjin; Pan, Jeong Hoon; Kim, Sung Hwan; Lee, Jin Hyup; Park, Jeen-Woo

2018-05-19

The key role of oxidative stress in alcoholic liver disease (ALD) has been established by the large body of evidence from previous studies. Excessive consumption of ethanol induces the production of a variety of reactive oxygen species (ROS) in the liver, such as superoxide, H 2 O 2 , and hydroxyl radical. These products activate oxidant-sensitive signaling cascades and modulators of apoptosis. Because ROS accumulation is closely related to ALD, a number of studies have investigated the benefits of antioxidants. Recent studies demonstrated that polyphenol chlorogenic acid (CGA) has antioxidant properties and health benefits, such as reduction of relative risk of cardiovascular diseases and hepatoprotective effects against acetaminophen toxicity. However, the protective effects of CGA against ALD have not been studied in detail. We hypothesize that CGA plays a role in preventing ALD through its antioxidant properties. In this study, we investigated the protective effects of CGA against liver injuries in vivo. Reduced alcohol-induced-steatosis, apoptotic cell death, and fibrosis due to reduced levels of oxidative stress were observed. These findings suggest that CGA treatment can be an effective approach to attenuate ALD through the suppression of oxidative stress. Copyright © 2018. Published by Elsevier B.V.

Antioxidant and anti-ageing activities of citrus-based juice mixture.

PubMed

Kim, Dan-Bi; Shin, Gi-Hae; Kim, Jae-Min; Kim, Young-Hyun; Lee, Jin-Ha; Lee, Jong Seok; Song, Hye-Jin; Choe, Soo Young; Park, In-Jae; Cho, Ju-Hyun; Lee, Ok-Hawn

2016-03-01

The production of excessive reactive oxygen species by exposure to oxidative stress and solar radiation are primary factors in skin damage. We examined the effects of a citrus-based juice mixture and its bioactive compounds on antioxidant and anti-ageing activities in human dermal fibroblasts and hairless mice via the regulation of antioxidant enzymes and the mitogen-activated protein kinase pathway. The citrus-based juice mixture reduced H2O2-induced cell damage and intracellular reactive oxygen species production in human dermal fibroblasts. Citrus-based juice mixture pretreatment suppressed the activation of the H2O2-mediated mitogen-activated protein kinase pathway by activating the expression of activator protein 1 and matrix metalloproteinases. Moreover, it increased the expression levels of antioxidant enzymes such as glutathione reductase, catalase and manganese superoxide dismutase. In addition, oral administration of the citrus-based juice mixture decreased skin thickness and wrinkle formation and increased collagen content on an ultraviolet light B-exposed hairless mouse. These results indicate that the citrus-based juice mixture is a potentially healthy beverage for the prevention of oxidative stress-induced premature skin ageing. Copyright © 2015 Elsevier Ltd. All rights reserved.

Gas Suppression via Copper Interlayers in Magnetron Sputtered Al-Cu2O Multilayers.

PubMed

Kinsey, Alex H; Slusarski, Kyle; Sosa, Steven; Weihs, Timothy P

2017-07-05

The use of thin-foil, self-propagating thermite reactions to bond components successfully depends on the ability to suppress gas generation and avoid pore formation during the exothermic production of brazes. To study the mechanisms of vapor production in diluted thermites, thin film multilayer Al-Cu-Cu 2 O-Cu foils are produced via magnetron sputtering, where the Cu layer thickness is systematically increased from 0 to 100 nm in 25 nm increments. The excess Cu layers act as diffusion barriers, limiting the transport of oxygen from the oxide to the Al fuel, as determined by slow heating differential scanning calorimetry experiments. Furthermore, by adding excess Cu to the system, the temperature of the self-propagating thermite reactions drops below the boiling point of Cu, eliminating the metal vapor production. It is determined that Cu vapor production can be eliminated by increasing the Cu interlayer thickness above 50 nm. However, the porous nature of the final products suggests that only metal vapor production is suppressed via dilution. Gas generation via oxygen release is still capable of producing a porous reaction product.

Average structure and local configuration of excess oxygen in UO(2+x).

PubMed

Wang, Jianwei; Ewing, Rodney C; Becker, Udo

2014-03-19

Determination of the local configuration of interacting defects in a crystalline, periodic solid is problematic because defects typically do not have a long-range periodicity. Uranium dioxide, the primary fuel for fission reactors, exists in hyperstoichiometric form, UO(2+x). Those excess oxygen atoms occur as interstitial defects, and these defects are not random but rather partially ordered. The widely-accepted model to date, the Willis cluster based on neutron diffraction, cannot be reconciled with the first-principles molecular dynamics simulations present here. We demonstrate that the Willis cluster is a fair representation of the numerical ratio of different interstitial O atoms; however, the model does not represent the actual local configuration. The simulations show that the average structure of UO(2+x) involves a combination of defect structures including split di-interstitial, di-interstitial, mono-interstitial, and the Willis cluster, and the latter is a transition state that provides for the fast diffusion of the defect cluster. The results provide new insights in differentiating the average structure from the local configuration of defects in a solid and the transport properties of UO(2+x).

41 CFR 50-204.31 - Reports of overexposure and excessive levels and concentrations.

Code of Federal Regulations, 2010 CFR

2010-07-01

... excessive levels and concentrations. (a) In addition to any notification required by § 50-204.30 each employer shall make a report in writing within 30 days to the Regional Director of the appropriate Wage and... and excessive levels and concentrations. 50-204.31 Section 50-204.31 Public Contracts and Property...

Coccidian Infection Causes Oxidative Damage in Greenfinches

PubMed Central

Sepp, Tuul; Karu, Ulvi; Blount, Jonathan D.; Sild, Elin; Männiste, Marju; Hõrak, Peeter

2012-01-01

The main tenet of immunoecology is that individual variation in immune responsiveness is caused by the costs of immune responses to the hosts. Oxidative damage resulting from the excessive production of reactive oxygen species during immune response is hypothesized to form one of such costs. We tested this hypothesis in experimental coccidian infection model in greenfinches Carduelis chloris. Administration of isosporan coccidians to experimental birds did not affect indices of antioxidant protection (TAC and OXY), plasma triglyceride and carotenoid levels or body mass, indicating that pathological consequences of infection were generally mild. Infected birds had on average 8% higher levels of plasma malondialdehyde (MDA, a toxic end-product of lipid peroxidation) than un-infected birds. The birds that had highest MDA levels subsequent to experimental infection experienced the highest decrease in infection intensity. This observation is consistent with the idea that oxidative stress is a causative agent in the control of coccidiosis and supports the concept of oxidative costs of immune responses and parasite resistance. The finding that oxidative damage accompanies even the mild infection with a common parasite highlights the relevance of oxidative stress biology for the immunoecological research. PMID:22615772

Exercise-stimulated FGF23 promotes exercise performance via controlling the excess reactive oxygen species production and enhancing mitochondrial function in skeletal muscle.

PubMed

Li, Dong-Jie; Fu, Hui; Zhao, Ting; Ni, Min; Shen, Fu-Ming

2016-05-01

Physical exercise induces many adaptive changes in skeletal muscle and the whole body and improves metabolic characteristics. Fibroblast growth-factor 23 (FGF23) is a unique member of the FGF family that acts as a hormone regulating phosphate metabolism, calcitriol concentration, and kidney functions. The role of FGF23 in exercise and skeletal muscle is largely unknown yet. C57BL/6J mice were exercised on a motor treadmill. Mice serum FGF23 levels; FGF23 mRNA expression in various organs including the liver, heart, skeletal muscle tissue, and thyroid; and FGF23 receptor Klotho mRNA expression were examined using enzyme-linked immunosorbent assay, real-time polymerase chain reaction, and immunoblotting, respectively, after a single bout of acute exercise (60min), exhaustive exercise, and chronic prolonged exercise (60min every day for one week). C57BL/6J mice were injected with recombinant FGF23 (100mg/kg, twice per day, i.p.) or vehicle control (saline) for 3days, and then the exercise performance, reactive oxygen species (ROS), H2O2 production, and mitochondrial functional biomarkers in muscle (gene expression of sirtuin 1, PPAR-δ, PGC-1α and mitochondrial transcription factor A [TFAM], and citrate synthase activity) were assayed. Three forms of exercise, acute exercise, exhaustive exercise, and chronic exercise, increased serum FGF23 levels. However, only chronic exercise upregulated FGF23 mRNA and protein expression in skeletal muscle. FGF23 mRNA expression in the heart, liver, and thyroid was not affected. FGF23 protein was mainly located in the cytoplasm in skeletal muscle tissue and the localization of FGF23 was not altered by exercise. Exogenous FGF23 treatment significantly extended the time to exhaustion and reduced the exercise-induced ROS and H2O2 production. FGF23 treatment increased the mRNA level of PPAR-δ and citrate synthase activity, but did not influence the mRNA expression of sirtuin 1, PGC-1α, and TFAM in skeletal muscle. These results demonstrate that exercise-stimulated FGF23 promotes exercise performance via controlling the excess ROS production and enhancing mitochondrial function in skeletal muscle, which reveals an entirely novel role of FGF23 in skeletal muscle. Copyright © 2016 Elsevier Inc. All rights reserved.

Lipoic acid mitigates oxidative stress and recovers metabolic distortions in salt-stressed wheat seedlings by modulating ion homeostasis, the osmo-regulator level and antioxidant system.

PubMed

Gorcek, Zeynep; Erdal, Serkan

2015-11-01

Soil salinity is one of the most detrimental environmental factors affecting the growth of plants and limiting their agricultural productivity. This study investigated whether exogenous lipoic acid (LA) pretreatment plays a role in promoting salt tolerance in wheat seedlings. The seedlings were treated with LA (1.75 mmol L(-1)) and salt (100 mmol L(-1) NaCl) separately and a combination of them. Salt stress significantly reduced relative water content, leaf surface area, ribulose bisphosphate carboxylase expression, and chlorophyll content but increased the content of osmo-regulator protein, carbohydrates and proline. In addition, salinity led to an imbalance in the inorganic composition of wheat leaves. While it elevated Na(+) content compared to control, Ca content and K(+)/Na(+) ratio were reduced. Under saline conditions, despite increases in antioxidant enzyme activity and levels of antioxidant compounds (ascorbate and glutathione), the content of reactive oxygen species (superoxide anion, hydrogen peroxide) and malondialdehyde were higher than in control seedlings. LA significantly promoted osmo-regulator level and antioxidant enzyme activities compared to stressed seedlings alone. Also, it both increased levels of ascorbate and glutathione and regenerated their oxidised forms, thus contributing to maintaining cellular redox status. Similarly, LA prevented excessive accumulation of Na(+) and promoted K(+)/Na(+) ratio and Ca content. Reactive oxygen species content was significantly reduced, and the inhibitions in the above parameters markedly recovered. LA reduced salinity-induced oxidative damage and thus contributed to the growth and development of plants in saline soils by modulating ion homeostasis between plant and soil as well as in osmo-regulator content and antioxidant system. © 2014 Society of Chemical Industry.

Effects of environmental cadmium and lead exposure on adults neighboring a discharge: Evidences of adverse health effects.

PubMed

Cabral, Mathilde; Toure, Aminata; Garçon, Guillaume; Diop, Cheikh; Bouhsina, Saâd; Dewaele, Dorothée; Cazier, Fabrice; Courcot, Dominique; Tall-Dia, Anta; Shirali, Pirouz; Diouf, Amadou; Fall, Mamadou; Verdin, Anthony

2015-11-01

The purpose of the study was to determine Pb and Cd concentrations in humans and to assess the effect of co-exposure to these metals on biomarkers of oxidative stress and nephrotoxicity. Blood and urine levels of Pb and Cd, oxidative stress and urinary renal biomarkers were measured in 77 subjects neighboring a discharge and 52 in the control site. Exposed subjects showed significantly higher levels of lead and cadmium in blood and urine than the controls. Excessive production of reactive oxygen species induced by these metals in exposed subjects conducted to a decrease in antioxidant defense system (GPx, Selenium, GSH) and an increase in lipid peroxidation (MDA). Moreover, changes in markers of nephrotoxicity (high urinary concentrations of total protein, RBP and CC16, as well as GSTα and LDH increased activities) suggested the occurrence of discrete and early signs of impaired renal function for the discharge neighboring population. Copyright © 2015 Elsevier Ltd. All rights reserved.

Potential Therapeutic Benefits of Green and Fermented Rooibos (Aspalathus linearis) in Dermal Wound Healing.

PubMed

Pringle, Nadine A; Koekemoer, Trevor C; Holzer, Andrea; Young, Carly; Venables, Luanne; van de Venter, Maryna

2018-02-28

The process of wound healing constitutes an ordered sequence of events that provides numerous opportunities for therapeutic intervention to improve wound repair. Rooibos, Aspalathus linearis , is a popular ingredient in skin care products, however, little scientific data exists exploring its therapeutic potential. In the present study, we evaluated the effects of fermented and aspalathin-enriched green rooibos in various in vitro models representative of dermal wound healing. Treatment of RAW 264.7 macrophages with fermented rooibos resulted in increased nitric oxide production as well as increased levels of cellular inducible nitric oxide synthase and cyclooxygenase-2, which are typical markers for classically activated macrophages. In contrast, the green extract was devoid of such activity. Using glycated gelatin as a model to mimic diabetic wounds, only the green extract showed potential to reduce cyclooxygenase-2 levels. Considering the role of reactive oxygen species in wound healing, the effects of rooibos on oxidative stress and cell death in human dermal fibroblasts was evaluated. Both fermented and green rooibos decreased cellular reactive oxygen species and attenuated apoptotic/necrotic cell death. Our findings highlight several properties that support the therapeutic potential of rooibos, and demonstrate that green and fermented rooibos present distinctly different properties with regards to their application in wound healing. The proinflammatory nature of fermented rooibos may have therapeutic value for wounds characterised with a delayed initial inflammatory phase, such as early diabetic wounds. The green extract is more suited to wounds burdened with excessive inflammation as it attenuated cyclooxygenase-2 levels and effectively protected fibroblasts against oxidative stress. Georg Thieme Verlag KG Stuttgart · New York.

A physically-modified saline suppresses neuronal apoptosis, attenuates tau phosphorylation and protects memory in an animal model of Alzheimer's disease.

PubMed

Modi, Khushbu K; Jana, Arundhati; Ghosh, Supurna; Watson, Richard; Pahan, Kalipada

2014-01-01

Alzheimer's disease (AD), the leading cause of dementia in the aging population, is characterized by the presence of neuritic plaques, neurofibrillary tangles and extensive neuronal apoptosis. Neuritic plaques are mainly composed of aggregates of amyloid-β (Aβ) protein while neurofibrillary tangles are composed of the hyperphosphorylated tau protein. Despite intense investigations, no effective therapy is currently available to halt the progression of this disease. Here, we have undertaken a novel approach to attenuate apoptosis and tau phosphorylation in cultured neuronal cells and in a transgenic animal model of AD. RNS60 is a 0.9% saline solution containing oxygenated nanobubbles that is generated by subjecting normal saline to Taylor-Couette-Poiseuille (TCP) flow under elevated oxygen pressure. In our experiments, fibrillar Aβ1-42, but not the reverse peptide Aβ42-1, induced apoptosis and cell death in human SHSY5Y neuronal cells. RNS60, but not NS (normal saline), RNS10.3 (TCP-modified saline without excess oxygen) or PNS60 (saline containing excess oxygen without TCP modification), attenuated Aβ(1-42)-induced cell death. RNS60 inhibited neuronal cell death via activation of the type 1A phosphatidylinositol-3 (PI-3) kinase-Akt-BAD pathway. Furthermore, RNS60 also decreased Aβ(1-42)-induced tau phosphorylation via (PI-3 kinase-Akt)-mediated inhibition of GSK-3β. Similarly, RNS60 treatment suppressed neuronal apoptosis, attenuated Tau phosphorylation, inhibited glial activation, and reduced the burden of Aβ in the hippocampus and protected memory and learning in 5XFAD transgenic mouse model of AD. Therefore, RNS60 may be a promising pharmaceutical candidate in halting or delaying the progression of AD.

Reperfusion injury and reactive oxygen species: The evolution of a concept☆

PubMed Central

Granger, D. Neil; Kvietys, Peter R.

2015-01-01

Reperfusion injury, the paradoxical tissue response that is manifested by blood flow-deprived and oxygen-starved organs following the restoration of blood flow and tissue oxygenation, has been a focus of basic and clinical research for over 4-decades. While a variety of molecular mechanisms have been proposed to explain this phenomenon, excess production of reactive oxygen species (ROS) continues to receive much attention as a critical factor in the genesis of reperfusion injury. As a consequence, considerable effort has been devoted to identifying the dominant cellular and enzymatic sources of excess ROS production following ischemia-reperfusion (I/R). Of the potential ROS sources described to date, xanthine oxidase, NADPH oxidase (Nox), mitochondria, and uncoupled nitric oxide synthase have gained a status as the most likely contributors to reperfusion-induced oxidative stress and represent priority targets for therapeutic intervention against reperfusion-induced organ dysfunction and tissue damage. Although all four enzymatic sources are present in most tissues and are likely to play some role in reperfusion injury, priority and emphasis has been given to specific ROS sources that are enriched in certain tissues, such as xanthine oxidase in the gastrointestinal tract and mitochondria in the metabolically active heart and brain. The possibility that multiple ROS sources contribute to reperfusion injury in most tissues is supported by evidence demonstrating that redox-signaling enables ROS produced by one enzymatic source (e.g., Nox) to activate and enhance ROS production by a second source (e.g., mitochondria). This review provides a synopsis of the evidence implicating ROS in reperfusion injury, the clinical implications of this phenomenon, and summarizes current understanding of the four most frequently invoked enzymatic sources of ROS production in post-ischemic tissue. PMID:26484802

Effect of continuous and intermittent bouts of isocaloric cycling and running exercise on excess postexercise oxygen consumption.

PubMed

Cunha, Felipe A; Midgley, Adrian W; McNaughton, Lars R; Farinatti, Paulo T V

2016-02-01

The purpose of this study was to investigate excess postexercise oxygen consumption (EPOC) induced by isocaloric bouts of continuous and intermittent running and cycling exercise. This was a counterbalanced randomized cross-over study. Ten healthy men, aged 23-34yr, performed six bouts of exercise: (a) two maximal cardiopulmonary exercise tests for running and cycling to determine exercise modality-specific peak oxygen uptake (VO2peak); and (b) four isocaloric exercise bouts (two continuous bouts expending 400kcal and two intermittent bouts split into 2×200kcal) performed at 75% of the running and cycling oxygen uptake reserve. Exercise bouts were separated by 72h and performed in a randomized, counter-balanced order. The VO2 was monitored for 60-min postexercise and for 60-min during a control non-exercise day. The VO2 was significantly greater in all exercise conditions compared to the control session (P<0.001). The combined magnitude of the EPOC from the two intermittent bouts was significantly greater than that of the continuous cycling (mean difference=3.5L, P=0.001) and running (mean difference=6.4L, P<0.001). The exercise modality had a significant effect on net EPOC, where running elicited a higher net EPOC than cycling (mean difference=2.2L, P<0.001). Intermittent exercise increased the EPOC compared to a continuous exercise bout of equivalent energy expenditure. Furthermore, the magnitude of EPOC was influenced by exercise modality, with the greatest EPOC occurring with isocaloric exercise involving larger muscle mass (i.e., treadmill running vs. cycling). Copyright © 2015 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Oxygen-Inducible Glutamate Oxaloacetate Transaminase as Protective Switch Transforming Neurotoxic Glutamate to Metabolic Fuel During Acute Ischemic Stroke

PubMed Central

Rink, Cameron; Gnyawali, Surya; Peterson, Laura

2011-01-01

Abstract This work rests on our previous report (J Cereb Blood Flow Metab 30: 1275–1287, 2010) recognizing that glutamate (Glu) oxaloacetate transaminase (GOT) is induced when brain tissue hypoxia is corrected during acute ischemic stroke (AIS). GOT can metabolize Glu into tricarboxylic acid cycle intermediates and may therefore be useful to harness excess neurotoxic extracellular Glu during AIS as a metabolic substrate. We report that in cultured neural cells challenged with hypoglycemia, extracellular Glu can support cell survival as long as there is sufficient oxygenation. This effect is abrogated by GOT knockdown. In a rodent model of AIS, supplemental oxygen (100% O2 inhaled) during ischemia significantly increased GOT expression and activity in the stroke-affected brain tissue and prevented loss of ATP. Biochemical analyses and in vivo magnetic resonance spectroscopy during stroke demonstrated that such elevated GOT decreased Glu levels at the stroke-affected site. In vivo lentiviral gene delivery of GOT minimized lesion volume, whereas GOT knockdown worsened stroke outcomes. Thus, brain tissue GOT emerges as a novel target in managing stroke outcomes. This work demonstrates that correction of hypoxia during AIS can help clear extracellular neurotoxic Glu by enabling utilization of this amino acid as a metabolic fuel to support survival of the hypoglycemic brain tissue. Strategies to mitigate extracellular Glu-mediated neurodegeneration via blocking receptor-mediated excitotoxicity have failed in clinical trials. We introduce the concept that under hypoglycemic conditions extracellular Glu can be transformed from a neurotoxin to a survival factor by GOT, provided there is sufficient oxygen to sustain cellular respiration. Antioxid. Redox Signal. 14, 1777–1785. PMID:21361730

Oxygen in the critically ill: friend or foe?

PubMed

Damiani, Elisa; Donati, Abele; Girardis, Massimo

2018-04-01

To examine the potential harmful effects of hyperoxia and summarize the results of most recent clinical studies evaluating oxygen therapy in critically ill patients. Excessive oxygen supplementation may have detrimental pulmonary and systemic effects because of enhanced oxidative stress and inflammation. Hyperoxia-induced lung injury includes altered surfactant protein composition, reduced mucociliary clearance and histological damage, resulting in atelectasis, reduced lung compliance and increased risk of infections. Hyperoxemia causes vasoconstriction, reduction in coronary blood flow and cardiac output and may alter microvascular perfusion. Observational studies showed a close relationship between hyperoxemia and increased mortality in several subsets of critically ill patients. In absence of hypoxemia, the routine use of oxygen therapy in patients with myocardial infarction, stroke, traumatic brain injury, cardiac arrest and sepsis, showed no benefit but rather it seems to be harmful. In patients admitted to intensive care unit, a conservative oxygen therapy aimed to maintain arterial oxygenation within physiological range has been proved to be well tolerated and may improve outcome. Liberal O2 use and unnecessary hyperoxia may be detrimental in critically ill patients. The current evidence supports the use of a conservative strategy in O2 therapy to avoid patient exposure to unnecessary hyperoxemia.

Automated Reflectance Measurement System Designed and Fabricated to Determine the Limits of Atomic Oxygen Treatment of Art Through Contrast Optimization

NASA Technical Reports Server (NTRS)

Sechkar, Edward A.; Stueber, Thomas J.; Rutledge, Sharon K.

2000-01-01

Atomic oxygen generated in ground-based research facilities has been used to not only test erosion of candidate spacecraft materials but as a noncontact technique for removing organic deposits from the surfaces of artwork. NASA has patented the use of atomic oxygen to remove carbon-based soot contamination from fire-damaged artwork. The process of cleaning soot-damaged paintings with atomic oxygen requires exposures for variable lengths of time, dependent on the condition of a painting. Care must be exercised while cleaning to prevent the removal of pigment. The cleaning process must be stopped as soon as visual inspection or surface reflectance measurements indicate that cleaning is complete. Both techniques rely on optical comparisons of known bright locations against known dark locations on the artwork being cleaned. Difficulties arise with these techniques when either a known bright or dark location cannot be determined readily. Furthermore, dark locations will lighten with excessive exposure to atomic oxygen. Therefore, an automated test instrument to quantitatively characterize cleaning progression was designed and developed at the NASA Glenn Research Center at Lewis Field to determine when atomic oxygen cleaning is complete.

Carbon stars with oxygen-rich circumstellar material

NASA Technical Reports Server (NTRS)

Jura, Michael; Hawkins, I.

1991-01-01

The IUE satellite was used to search for companions to two carbon-rich stars with oxygen-rich circumstellar envelopes, EU And and V778 Cyg. Depending upon the amount of interstellar extinction and distances (probably between 1 and 2 kpc from the Sun) to these two stars, upper limits were placed between approx. 1.5 and 6 solar mass to the mass of any main sequence companions. For the 'near' distance of 1 kpc, it seems unlikely that there are white dwarf companions because the detection would be expected of ultraviolet emission from accretion of red giant wind material onto the white dwarf. A new model is proposed to explain the oxygen-rich envelopes. If these stars have a high nitrogen abundance, the carbon that is in excess of the oxygen may be carried in the circumstellar envelopes in HCN rather than C2H2 which is a likely key seed molecule for the formation of carbon grains. Consequently, carbon particles may not form; instead, oxygen-rich silicate dust may nucleate from the SiO present in the outflow.

Conduction Channel Formation and Dissolution Due to Oxygen Thermophoresis/Diffusion in Hafnium Oxide Memristors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Suhas; Wang, Ziwen; Huang, Xiaopeng

Due to the favorable operating power, endurance, speed, and density., transition-metal-oxide memristors, or resistive random-access memory (RRAM) switches, are under intense development for storage-class memory. Their commercial deployment critically depends on predictive compact models based on understanding nanoscale physiocochemical forces, which remains elusive and controversial owing to the difficulties in directly observing atomic motions during resistive switching, Here, using scanning transmission synchrotron X-ray spectromicroscopy to study in situ switching of hafnium oxide memristors, we directly observed the formation of a localized oxygen-deficiency-derived conductive channel surrounded by a low-conductivity ring of excess oxygen. Subsequent thermal annealing homogenized the segregated oxygen, resettingmore » the cells toward their as-grown resistance state. We show that the formation and dissolution of the conduction channel are successfully modeled by radial thermophoresis and Fick diffusion of oxygen atoms driven by Joule heating. This confirmation and quantification of two opposing nanoscale radial forces that affect bipolar memristor switching are important components for any future physics-based compact model for the electronic switching of these devices.« less

Oxygen delivery using neonatal self-inflating bags without reservoirs.

PubMed

Sugiura, Takahiro; Urushibata, Rei; Komatsu, Kenji; Shioda, Tsutomu; Ota, Tatsuki; Sato, Megumi; Okubo, Yumiko; Fukuoka, Tetsuya; Hosono, Shigeharu; Tamura, Masanori

2017-02-01

Guidelines recommend avoiding excessive oxygen during neonatal resuscitation. Recent studies have suggested that oxygen titration can be achieved using a self-inflating bag, but data on the effectiveness of resuscitators used in neonatal ventilation are scarce, The aim of this study was therefore to determine the amount of oxygen delivered using several brands of neonatal self-inflating resuscitation bags without reservoirs under different conditions with regard to oxygen flow rate, ventilation rate (VR), peak inspiratory pressure (PIP) range, and test lung compliance. Oxygen concentration was measured under a variety of conditions. Combinations of oxygen flow rate (10, 5.0, 3.0 and 1.0 L/min), VR (40, 60 inflations/min), PIP range (20-25 cmH 2 O, 35-40 cmH 2 O), and test lung compliance (0.6, 1.0, 3.0, and 5.0 mL/cmH 2 O) were examined using six kinds of self-inflating bag. Delivered oxygen concentration varied widely (30.1-96.7%) and had a significant positive correlation with gas flow rate in all of the bags. Delivered oxygen concentration was also negatively correlated with PIP in all of the bags and with VR in some of them. Test lung compliance did not affect delivered oxygen concentration. The use of neonatal resuscitation self-inflating bags without reservoirs resulted in different delivered oxygen concentrations depending on gas flow rate, VR, PIP, and manufacturer, but not on lung compliance. This suggests that targeted oxygen concentrations could be delivered, even in lungs with decreased compliance, during resuscitation. © 2016 Japan Pediatric Society.

Valuation of OSA process and folic acid addition as excess sludge minimization alternatives applied in the activated sludge process.

PubMed

Martins, C L; Velho, V F; Ramos, S R A; Pires, A S C D; Duarte, E C N F A; Costa, R H R

2016-01-01

The aim of this study was to investigate the ability of the oxic-settling-anaerobic (OSA)-process and the folic acid addition applied in the activated sludge process to reduce the excess sludge production. The study was monitored during two distinct periods: activated sludge system with OSA-process, and activated sludge system with folic acid addition. The observed sludge yields (Yobs) were 0.30 and 0.08 kgTSS kg(-1) chemical oxygen demand (COD), control phase and OSA-process (period 1); 0.33 and 0.18 kgTSS kg(-1) COD, control phase and folic acid addition (period 2). The Yobs decreased by 73 and 45% in phases with the OSA-process and folic acid addition, respectively, compared with the control phases. The sludge minimization alternatives result in a decrease in excess sludge production, without negatively affecting the performance of the effluent treatment.

40 CFR 201.11 - Standard for locomotive operation under stationary conditions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... completed on or before December 31, 1979, which produces A-weighted sound levels in excess of 93 dB at any..., 1979, which produces A-weighted sound levels in excess of 87 dB at any throttle setting except idle... December 31, 1979, which produces A-weighted sound levels in excess of 87 dB at any throttle setting except...

40 CFR 201.11 - Standard for locomotive operation under stationary conditions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... completed on or before December 31, 1979, which produces A-weighted sound levels in excess of 93 dB at any..., 1979, which produces A-weighted sound levels in excess of 87 dB at any throttle setting except idle... December 31, 1979, which produces A-weighted sound levels in excess of 87 dB at any throttle setting except...

Nitrative and Oxidative Stress in Toxicology and Disease

PubMed Central

Roberts, Ruth A.; Laskin, Debra L.; Smith, Charles V.; Robertson, Fredika M.; Allen, Erin M. G.; Doorn, Jonathan A.; Slikker, William

2009-01-01

Persistent inflammation and the generation of reactive oxygen and nitrogen species play pivotal roles in tissue injury during disease pathogenesis and as a reaction to toxicant exposures. The associated oxidative and nitrative stress promote diverse pathologic reactions including neurodegenerative disorders, atherosclerosis, chronic inflammation, cancer, and premature labor and stillbirth. These effects occur via sustained inflammation, cellular proliferation and cytotoxicity and via induction of a proangiogenic environment. For example, exposure to the ubiquitous air pollutant ozone leads to generation of reactive oxygen and nitrogen species in lung macrophages that play a key role in subsequent tissue damage. Similarly, studies indicate that genes involved in regulating oxidative stress are altered by anesthetic treatment resulting in brain injury, most notable during development. In addition to a role in tissue injury in the brain, inflammation, and oxidative stress are implicated in Parkinson's disease, a neurodegenerative disease characterized by the loss of dopamine neurons. Recent data suggest a mechanistic link between oxidative stress and elevated levels of 3,4-dihydroxyphenylacetaldehyde, a neurotoxin endogenous to dopamine neurons. These findings have significant implications for development of therapeutics and identification of novel biomarkers for Parkinson's disease pathogenesis. Oxidative and nitrative stress is also thought to play a role in creating the proinflammatory microenvironment associated with the aggressive phenotype of inflammatory breast cancer. An understanding of fundamental concepts of oxidative and nitrative stress can underpin a rational plan of treatment for diseases and toxicities associated with excessive production of reactive oxygen and nitrogen species. PMID:19656995

Partially oxidised organic components in urban aerosol using GCXGC-TOF/MS

NASA Astrophysics Data System (ADS)

Hamilton, J. F.; Webb, P. J.; Lewis, A. C.; Hopkins, J. R.; Smith, S.; Davy, P.

2004-08-01

Partially oxidised organic compounds associated with PM2.5 aerosol collected in London, England, have been analysed using direct thermal desorption coupled to comprehensive gas chromatography-time of flight mass spectrometry (GCXGC-TOF/MS). Over 10000 individual organic components were isolated from around 10µg of aerosol material in a single procedure and with no sample pre-treatment. Chemical functionalities observed using this analytical technique ranged from alkanes to poly-oxygenated species. The chemical band structures commonly used in GCXGC for group type identifications overlap for this sample type, and have required mass spectrometry as an additional level of instrument dimensionality. An investigation of oxygenated volatile organic compounds (o-VOC) contained within urban aerosol has been performed and in a typical sample around 130 o-VOCs were identified based on retention behaviour and spectral match. In excess of 100 other oxygenated species were also observed but lack of mass spectral library or pure components prevents positive identification. Many of the carbonyl species observed could be mechanistically linked to gas phase aromatic hydrocarbon oxidation and there is good agreement in terms of speciation between the urban samples analysed here and those degradation products observed in smog chamber experiments of aromatic oxidation. The presence of partially oxidised species such as linear chain aldehydes and ketones and cyclic products such as furanones suggests that species generated early in the oxidative process may undergo gas to particle partitioning despite their relatively high volatility.

Partially oxidised organic components in urban aerosol using GCXGC-TOF/MS

NASA Astrophysics Data System (ADS)

Hamilton, J.; Webb, P.; Lewis, A.; Hopkins, J.; Smith, S.; Davy, P.

2004-03-01

Partially oxidised organic compounds associated with PM2.5 aerosol collected in London, England, have been analysed using direct thermal desorption coupled to comprehensive gas chromatography-time of flight mass spectrometry (GCXGC-OF/MS). Over 10 000 individual organic components were isolated from around 10 μg of aerosol material in a single procedure and with no sample pre-treatment. Chemical functionalities observed using this analytical technique ranged from alkanes to poly-oxygenated species. The chemical band structures commonly used in GCXGC for group type identifications overlap for this sample type, and have required mass spectrometry as an additional level of instrument dimensionality. An investigation of oxygenated volatile organic compounds (o-VOC) contained within urban aerosol has been performed and in a typical sample around 130 o-VOCs were identified based on retention behaviour and spectral match. In excess of 100 other oxygenated species were also observed but lack of mass spectral library or pure components prevents positive identification. Many of the carbonyl species observed could be mechanistically linked to gas phase aromatic hydrocarbon oxidation and there is good agreement in terms of speciation between the urban samples analysed here and those degradation products observed in smog chamber experiments of aromatic oxidation. The presence of partially oxidised species such as linear chain aldehydes and ketones and cyclic products such as furanones suggests that species generated relatively early in the oxidative process may undergo gas to particle partitioning despite their relatively high volatility.

Hyperoxia activates ATM independent from mitochondrial ROS and dysfunction.

PubMed

Resseguie, Emily A; Staversky, Rhonda J; Brookes, Paul S; O'Reilly, Michael A

2015-08-01

High levels of oxygen (hyperoxia) are often used to treat individuals with respiratory distress, yet prolonged hyperoxia causes mitochondrial dysfunction and excessive reactive oxygen species (ROS) that can damage molecules such as DNA. Ataxia telangiectasia mutated (ATM) kinase is activated by nuclear DNA double strand breaks and delays hyperoxia-induced cell death through downstream targets p53 and p21. Evidence for its role in regulating mitochondrial function is emerging, yet it has not been determined if mitochondrial dysfunction or ROS activates ATM. Because ATM maintains mitochondrial homeostasis, we hypothesized that hyperoxia induces both mitochondrial dysfunction and ROS that activate ATM. In A549 lung epithelial cells, hyperoxia decreased mitochondrial respiratory reserve capacity at 12h and basal respiration by 48 h. ROS were significantly increased at 24h, yet mitochondrial DNA double strand breaks were not detected. ATM was not required for activating p53 when mitochondrial respiration was inhibited by chronic exposure to antimycin A. Also, ATM was not further activated by mitochondrial ROS, which were enhanced by depleting manganese superoxide dismutase (SOD2). In contrast, ATM dampened the accumulation of mitochondrial ROS during exposure to hyperoxia. Our findings suggest that hyperoxia-induced mitochondrial dysfunction and ROS do not activate ATM. ATM more likely carries out its canonical response to nuclear DNA damage and may function to attenuate mitochondrial ROS that contribute to oxygen toxicity. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Microcirculation assessment using an individualized model for diffuse reflectance spectroscopy and conventional laser Doppler flowmetry

NASA Astrophysics Data System (ADS)

Strömberg, Tomas; Karlsson, Hanna; Fredriksson, Ingemar; Nyström, Fredrik H.; Larsson, Marcus

2014-05-01

Microvascular assessment would benefit from co-registration of blood flow and hemoglobin oxygenation dynamics during stimulus response tests. We used a fiber-optic probe for simultaneous recording of white light diffuse reflectance (DRS; 475-850 nm) and laser Doppler flowmetry (LDF; 780 nm) spectra at two source-detector distances (0.4 and 1.2 mm). An inverse Monte Carlo algorithm, based on a multiparameter three-layer adaptive skin model, was used for analyzing DRS data. LDF spectra were conventionally processed for perfusion. The system was evaluated on volar forearm recordings of 33 healthy subjects during a 5-min systolic occlusion protocol. The calibration scheme and the optimal adaptive skin model fitted DRS spectra at both distances within 10%. During occlusion, perfusion decreased within 5 s while oxygenation decreased slowly (mean time constant 61 s dissociation of oxygen from hemoglobin). After occlusion release, perfusion and oxygenation increased within 3 s (inflow of oxygenized blood). The increased perfusion was due to increased blood tissue fraction and speed. The supranormal hemoglobin oxygenation indicates a blood flow in excess of metabolic demands. In conclusion, by integrating DRS and LDF in a fiber-optic probe, a powerful tool for assessment of blood flow and oxygenation in the same microvascular bed has been presented.

Microcirculation assessment using an individualized model for diffuse reflectance spectroscopy and conventional laser Doppler flowmetry.

PubMed

Strömberg, Tomas; Karlsson, Hanna; Fredriksson, Ingemar; Nyström, Fredrik H; Larsson, Marcus

2014-05-01

Microvascular assessment would benefit from co-registration of blood flow and hemoglobin oxygenation dynamics during stimulus response tests. We used a fiber-optic probe for simultaneous recording of white light diffuse reflectance (DRS; 475-850 nm) and laser Doppler flowmetry (LDF; 780 nm) spectra at two source-detector distances (0.4 and 1.2 mm). An inverse Monte Carlo algorithm, based on a multiparameter three-layer adaptive skin model, was used for analyzing DRS data. LDF spectra were conventionally processed for perfusion. The system was evaluated on volar forearm recordings of 33 healthy subjects during a 5-min systolic occlusion protocol. The calibration scheme and the optimal adaptive skin model fitted DRS spectra at both distances within 10%. During occlusion, perfusion decreased within 5 s while oxygenation decreased slowly (mean time constant 61 s; dissociation of oxygen from hemoglobin). After occlusion release, perfusion and oxygenation increased within 3 s (inflow of oxygenized blood). The increased perfusion was due to increased blood tissue fraction and speed. The supranormal hemoglobin oxygenation indicates a blood flow in excess of metabolic demands. In conclusion, by integrating DRS and LDF in a fiber-optic probe, a powerful tool for assessment of blood flow and oxygenation in the same microvascular bed has been presented.

Dynamic compartment specific changes in glutathione and ascorbate levels in Arabidopsis plants exposed to different light intensities

PubMed Central

2013-01-01

Background Excess light conditions induce the generation of reactive oxygen species (ROS) directly in the chloroplasts but also cause an accumulation and production of ROS in peroxisomes, cytosol and vacuoles. Antioxidants such as ascorbate and glutathione occur in all cell compartments where they detoxify ROS. In this study compartment specific changes in antioxidant levels and related enzymes were monitored among Arabidopsis wildtype plants and ascorbate and glutathione deficient mutants (vtc2-1 and pad2-1, respectively) exposed to different light intensities (50, 150 which was considered as control condition, 300, 700 and 1,500 μmol m-2 s-1) for 4 h and 14 d. Results The results revealed that wildtype plants reacted to short term exposure to excess light conditions with the accumulation of ascorbate and glutathione in chloroplasts, peroxisomes and the cytosol and an increased activity of catalase in the leaves. Long term exposure led to an accumulation of ascorbate and glutathione mainly in chloroplasts. In wildtype plants an accumulation of ascorbate and hydrogen peroxide (H2O2) could be observed in vacuoles when exposed to high light conditions. The pad2-1 mutant reacted to long term excess light exposure with an accumulation of ascorbate in peroxisomes whereas the vtc2-1 mutant reacted with an accumulation of glutathione in the chloroplasts (relative to the wildtype) and nuclei during long term high light conditions indicating an important role of these antioxidants in these cell compartments for the protection of the mutants against high light stress. Conclusion The results obtained in this study demonstrate that the accumulation of ascorbate and glutathione in chloroplasts, peroxisomes and the cytosol is an important reaction of plants to short term high light stress. The accumulation of ascorbate and H2O2 along the tonoplast and in vacuoles during these conditions indicates an important route for H2O2 detoxification under these conditions. PMID:23865417

Effects of the oxygenation level on formation of different reactive oxygen species during photodynamic therapy.

PubMed

Price, Michael; Heilbrun, Lance; Kessel, David

2013-01-01

We examined the effect of the oxygenation level on efficacy of two photosensitizing agents, both of which target lysosomes for photodamage, but via different photochemical pathways. Upon irradiation, the chlorin termed NPe6 forms singlet oxygen in high yield while the bacteriopheophorbide WST11 forms only oxygen radicals (in an aqueous environment). Photokilling efficacy by WST11 in cell culture was impaired when the atmospheric oxygen concentration was reduced from 20% to 1%, while photokilling by NPe6 was unaffected. Studies in a cell-free system revealed that the rates of photobleaching of these agents, as a function of the oxygenation level, were correlated with results described above. Moreover, the rate of formation of oxygen radicals by either agent was more sensitive to the level of oxygenation than was singlet oxygen formation by NPe6. These data indicate that the photochemical process that leads to oxygen radical formation is more dependent on the oxygenation level than is the pathway leading to formation of singlet oxygen. © 2013 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2013 The American Society of Photobiology.

Zinc interstitial threshold in Al-doped ZnO film: Effect on microstructure and optoelectronic properties

NASA Astrophysics Data System (ADS)

Singh, Chetan C.; Panda, Emila

2018-04-01

In order to know the threshold quantity of the zinc interstitials that contributes to an increase in carrier concentration in the Al-doped ZnO (AZO) films and their effect on the overall microstructure and optoelectronic properties of these films, in this work, Zn-rich-AZO and ZnO thin films are fabricated by adding excess zinc (from a zinc metallic target) during their deposition in RF magnetron sputtering and are then investigated using a wide range of experimental techniques. All these films are found to grow in a ZnO hexagonal wurtzite crystal structure with strong (002) orientation of the crystallites, with no indication of Al2O3, metallic Zn, and Al. The excessively introduced zinc in these AZO and/or ZnO films is found to increase the shallow donor level defects (i.e., zinc interstitials and oxygen-related electronic defect states), which is found to significantly increase the carrier concentration in these films. Additionally, aluminum is seen to enhance the creation of these electronic defect states in these films, thereby contributing more to the overall carrier concentration of these films. However, carrier mobility is found to decrease when the carrier concentration values are higher than 4 × 1020 cm-3, because of the electron-electron scattering. Whereas the optical band gap of the ZnO films is found to increase with increasing carrier concentration because of the Burstein-Moss shift, these decrease for the AZO films due to the band gap narrowing effect caused by excess carrier concentration.

Remote air lasing for trace detection

NASA Astrophysics Data System (ADS)

Dogariu, Arthur; Michael, James B.; Miles, Richard B.

2011-05-01

We demonstrate coherent light propagating backwards from a remotely generated high gain air laser. A short ultraviolet laser pulse tuned to a two-photon atomic oxygen electronic resonance at 226 nm simultaneously dissociates the oxygen molecules in air and excites the resulting atomic oxygen fragments. Due to the focal depth of the pumping laser, a millimeter long region of high gain is created in air for the atomic oxygen stimulated emission at 845nm. We demonstrate that the gain in excess of 60 cm-1 is responsible for both forward and backwards emission of a strong, collimated, coherent laser beam. We present evidence for coherent emission and characterize the backscattered laser beam while varying the pumping conditions. The optical gain and directional emission allows for six orders of magnitude enhancement for the backscattered emission when compared with the fluorescence emission collected into the same solid angle. . This opens new opportunities for the remote detection capabilities of trace species, and provides much greater range for the detection of optical molecular and atomic features from a distant target.

Thermionic converter performance with oxide collectors

NASA Technical Reports Server (NTRS)

Lieb, D.; Goodale, D.; Briere, T.; Balestra, C.

1977-01-01

Thermionic converters using a variety of metal oxide collector surfaces have been fabricated and tested. Both work function and power output data are presented and evaluated. Oxides of barium, strontium, zinc, tungsten and titanium have been incorporated into a variable spacing converter. Tungsten oxide was found to give the highest converter performance and to furnish oxygen for the emitter at the same time. Oxygenated emitters operate at reduced cesium pressure with an increase in electrode spacing. Electron spectroscopy for chemical analysis (ESCA) performed on several tungsten oxide collectors showed cesium penetration of the oxide layer, possibly forming a cesium tungstate bronze. Titanium oxide showed high performance but did not furnish oxygen for the emitter; strontium oxide, in the form of a sprayed layer, appeared to dissociate in the presence of cesium. Sprayed coatings of barium and zinc oxides produced collector work functions of about 1.3 eV, but had excessive series resistance. Lanthanum hexaboride, in combination with oxygen introduced through a silver tube, and cesium produced a low work function collector and better than average performance.

Quantum Dot-Based Luminescent Oxygen Channeling Assay for Potential Application in Homogeneous Bioassays.

PubMed

Zhuang, Si-Hui; Guo, Xin-Xin; Wu, Ying-Song; Chen, Zhen-Hua; Chen, Yao; Ren, Zhi-Qi; Liu, Tian-Cai

2016-01-01

The unique photoproperties of quantum dots are promising for potential application in bioassays. In the present study, quantum dots were applied to a luminescent oxygen channeling assay. The reaction system developed in this study was based on interaction of biotin with streptavidin. Carboxyl-modified polystyrene microspheres doped with quantum dots were biotinylated and used as acceptors. Photosensitizer-doped carboxyl-modified polystyrene microspheres were conjugated with streptavidin and used as donors. The results indicated that the singlet oxygen that was released from the donor beads diffused into the acceptor beads. The acceptor beads were then exited via thioxene, and were subsequently fluoresced. To avoid generating false positives, a high concentration (0.01 mg/mL) of quantum dots is required for application in homogeneous immunoassays. Compared to a conventional luminescent oxygen channeling assay, this quantum dots-based technique requires less time, and would be easier to automate and miniaturize because it requires no washing to remove excess labels.

Large-eddy simulation of oxygen transport and depletion in waterbodies

NASA Astrophysics Data System (ADS)

Scalo, Carlo; Piomelli, Ugo; Boegman, Leon

2010-11-01

Dissolved oxygen (DO) in water plays an important role in lake and marine ecosystems. Agricultural runoff may spur excessive plant growth on the water surface; when the plants die they sink to the bottom of the water bodies and decompose, consuming oxygen. Significant environmental (and economic) damage may result from the loss of aquatic life caused by the oxygen depletion. The study of DO transport and depletion dynamics in water bodies has, therefore, become increasingly important. We study this phenomenon by large-eddy simulations performed at laboratory scale. The equations governing the transport of momentum and of a scalar (the DO) in the fluid are coupled to a biochemical model for DO depletion in the permeable sediment bed [Higashino et al., Water Res. (38) 1, 2004)], and to an equation for the fluid transpiration in the porous medium. The simulations are in good agreement with previous calculations and experiments. We show that the results are sensitive to the biochemical and fluid dynamical properties of the sediment, which are very difficult to determine experimentally.

Oxy-fuel combustion with integrated pollution control

DOEpatents

Patrick, Brian R [Chicago, IL; Ochs, Thomas Lilburn [Albany, OR; Summers, Cathy Ann [Albany, OR; Oryshchyn, Danylo B [Philomath, OR; Turner, Paul Chandler [Independence, OR

2012-01-03

An oxygen fueled integrated pollutant removal and combustion system includes a combustion system and an integrated pollutant removal system. The combustion system includes a furnace having at least one burner that is configured to substantially prevent the introduction of air. An oxygen supply supplies oxygen at a predetermine purity greater than 21 percent and a carbon based fuel supply supplies a carbon based fuel. Oxygen and fuel are fed into the furnace in controlled proportion to each other and combustion is controlled to produce a flame temperature in excess of 3000 degrees F. and a flue gas stream containing CO2 and other gases. The flue gas stream is substantially void of non-fuel borne nitrogen containing combustion produced gaseous compounds. The integrated pollutant removal system includes at least one direct contact heat exchanger for bringing the flue gas into intimated contact with a cooling liquid to produce a pollutant-laden liquid stream and a stripped flue gas stream and at least one compressor for receiving and compressing the stripped flue gas stream.

Racial and ethnic disparities in hospital care resulting from air pollution in excess of federal standards.

PubMed

Hackbarth, Andrew D; Romley, John A; Goldman, Dana P

2011-10-01

This study investigates racial and ethnic disparities in hospital admission and emergency room visit rates resulting from exposure to ozone and fine particulate matter levels in excess of federal standards ("excess attributable risk"). We generate zip code-level ambient pollution exposures and hospital event rates using state datasets, and use pollution impact estimates in the epidemiological literature to calculate excess attributable risk for racial/ethnic groups in California over 2005-2007. We find that black residents experienced roughly 2.5 times the excess attributable risk of white residents. Hispanic residents were exposed to the highest levels of pollution, but experienced similar excess attributable risk to whites. Asian/Pacific Islander residents had substantially lower excess attributable risk compared to white. We estimate the distinct contributions of exposure and other factors to these results, and find that factors other than exposure can be critical determinants of pollution-related disparities. Copyright © 2011 Elsevier Ltd. All rights reserved.

The stream subsurface: nitrogen cycling and the cleansing function of hyporheic zones

Treesearch

Rhonda Mazza; Steve Wondzell; Jay Zarnetske

2014-01-01

Nitrogen is an element essential to plant growth and ecosystem productivity. Excess nitrogen, however, is a common water pollutant. It can lead to algal blooms that deplete the water's dissolved oxygen, creating "dead zones" devoid of fish and aquatic insects.Previous research showed that the subsurface area of a stream, known as the hyporheic...

A first-principles study of the preventive effects of Al and Mg doping on the degradation in LiNi0.8Co0.1Mn0.1O2 cathode materials.

PubMed

Min, Kyoungmin; Seo, Seung-Woo; Song, You Young; Lee, Hyo Sug; Cho, Eunseog

2017-01-18

First-principles calculations have been used to investigate the effects of Al and Mg doping on the prevention of degradation phenomena in Li(Ni 0.8 Co 0.1 Mn 0.1 )O 2 cathode materials. Specifically, we have examined the effects of dopants on the suppression of oxygen evolution and cation disordering, as well as their correlation. It is found that Al doping can suppress the formation of oxygen vacancies effectively, while Mg doping prevents the cation disordering behaviors, i.e., excess Ni and Li/Ni exchange, and Ni migration. This study also demonstrates that formation of oxygen vacancies can facilitate the construction of the cation disordering, and vice versa. Delithiation can increase the probabilities of formation of all defect types, especially oxygen vacancies. When oxygen vacancies are present, Ni can migrate to the Li site during delithiation. However, Al and Mg doping can inhibit Ni migration, even in structures with preformed oxygen defects. The analysis of atomic charge variations during delithiation demonstrates that the degree of oxidation behavior in oxygen atoms is alleviated in the case of Al doping, indicating the enhanced oxygen stability in this structure. In addition, changes in the lattice parameters during delithiation are suppressed in the Mg-doped structure, which suggests that Mg doping may improve the lattice stability.

Study of the structure, dielectric and ferroelectric behavior of BaBi{sub 4+δ}Ti{sub 4}O{sub 15} ceramics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khokhar, Anita, E-mail: mails4anita@gmail.com, E-mail: goyalphy@gmail.com; Goyal, Parveen K., E-mail: mails4anita@gmail.com, E-mail: goyalphy@gmail.com; Sreenivas, K.

2016-05-23

The structure and ferroelectric properties of excess bismuth doped barium bismuth titanate BaBi{sub 4+δ}Ti{sub 4}O{sub 15} (δ = 2 - 10 wt.%)) ceramics prepared by solid-state reaction method have been investigated. X-ray diffraction (XRD) confirms the formation of a single phase material with a change in the orthorhombic distortion with varying excess of bismuth content. There is no change in the phase transition temperature (T{sub m}) while the relaxor behaviour has been modified significantly with excess of bismuth doping. Saturated hysteresis loops with high remnant polarization (P{sub r} ~ 12.5  µC/cm{sup 2}), low coercive fields (E{sub c} ~ 26 kV/cm) aremore » measured and a high piezoelectric coefficient (d{sub 33} ~ 29 pC/N) is achieved in poled BaBi{sub 4}Ti{sub 4}O{sub 15} ceramics prepared with up to 8 wt.% of excess bismuth oxide. The improvement in the ferroelectric properties with increase in the excess bismuth content in BaBi{sub 4}Ti{sub 4}O{sub 15} ceramics has been explained in terms of changing oxygen vacancy concentration and structural relaxation. Tunable ferroelectric materials can be obtained by manipulating the doping amount of excess bismuth.« less

A new dawn for androgens: Novel lessons from 11-oxygenated C19 steroids.

PubMed

Pretorius, Elzette; Arlt, Wiebke; Storbeck, Karl-Heinz

2017-02-05

The abundant adrenal C19 steroid 11β-hydroxyandrostenedione (11OHA4) has been written off as a dead-end product of adrenal steroidogenesis. However, recent evidence has demonstrated that 11OHA4 is the precursor to the potent androgenic 11-oxygenated steroids, 11-ketotestosterone and 11-ketodihydrotestosterone, that bind and activate the human androgen receptor similarly to testosterone and DHT. The significance of this discovery becomes apparent when considering androgen dependent diseases such as castration resistant prostate cancer and diseases associated with androgen excess, e.g. congenital adrenal hyperplasia and polycystic ovary syndrome. In this review we describe the production and metabolism of 11-oxygenated steroids. We subsequently discuss their androgenic activity and highlight the putative role of these androgens in disease states. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Molecular structure of the lithium enolate of acetaldehyde

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lynch, T.J.; Newcomb, M.; Bergbreiter, D.E.

1980-11-21

Calculations of the structures of isomers of the lithium enolate of acetaldehyde done at the restricted Hartree-Fock level with the HONDO program on the CDC 7600 are reported. Using the standard 4-31 G basis set, these calculations produce excessively large bond angles, and this favors the most open of the three isomeric structures. Including the polarization functions on the carbons and oxygen and using the recent Dunning and Hayes (3s2p/2s) contraction indicates that the chirol enolates are the lowest energy structure. However, the differences of the various enolate structures are small and could be modified by solvent effects. These resultsmore » are proported to suggest that the enolates containing internal ligands may be prepared such that a new chirol center would exist by virtue of the counterion position. (BLM)« less

Spatially monitoring oxygen level in 3D microfabricated cell culture systems using optical oxygen sensing beads

PubMed Central

Wang, Lin; Acosta, Miguel A.; Leach, Jennie B.; Carrier, Rebecca L.

2013-01-01

Capability of measuring and monitoring local oxygen concentration at the single cell level (tens of microns scale) is often desirable but difficult to achieve in cell culture. In this study, biocompatible oxygen sensing beads were prepared and tested for their potential for real-time monitoring and mapping of local oxygen concentration in 3D micro-patterned cell culture systems. Each oxygen sensing bead is composed of a silica core loaded with both an oxygen sensitive Ru(Ph2phen3)Cl2 dye and oxygen insensitive Nile blue reference dye, and a poly-dimethylsiloxane (PDMS) shell rendering biocompatibility. Human intestinal epithelial Caco-2 cells were cultivated on a series of PDMS and type I collagen based substrates patterned with micro-well arrays for 3 or 7 days, and then brought into contact with oxygen sensing beads. Using an image analysis algorithm to convert florescence intensity of beads to partial oxygen pressure in the culture system, tens of microns-size oxygen sensing beads enabled the spatial measurement of local oxygen concentration in the microfabricated system. Results generally indicated lower oxygen level inside wells than on top of wells, and local oxygen level dependence on structural features of cell culture surfaces. Interestingly, chemical composition of cell culture substrates also appeared to affect oxygen level, with type-I collagen based cell culture systems having lower oxygen concentration compared to PDMS based cell culture systems. In general, results suggest that oxygen sensing beads can be utilized to achieve real-time and local monitoring of micro-environment oxygen level in 3D microfabricated cell culture systems. PMID:23443975

Spatially monitoring oxygen level in 3D microfabricated cell culture systems using optical oxygen sensing beads.

PubMed

Wang, Lin; Acosta, Miguel A; Leach, Jennie B; Carrier, Rebecca L

2013-04-21

Capability of measuring and monitoring local oxygen concentration at the single cell level (tens of microns scale) is often desirable but difficult to achieve in cell culture. In this study, biocompatible oxygen sensing beads were prepared and tested for their potential for real-time monitoring and mapping of local oxygen concentration in 3D micro-patterned cell culture systems. Each oxygen sensing bead is composed of a silica core loaded with both an oxygen sensitive Ru(Ph2phen3)Cl2 dye and oxygen insensitive Nile blue reference dye, and a poly-dimethylsiloxane (PDMS) shell rendering biocompatibility. Human intestinal epithelial Caco-2 cells were cultivated on a series of PDMS and type I collagen based substrates patterned with micro-well arrays for 3 or 7 days, and then brought into contact with oxygen sensing beads. Using an image analysis algorithm to convert florescence intensity of beads to partial oxygen pressure in the culture system, tens of microns-size oxygen sensing beads enabled the spatial measurement of local oxygen concentration in the microfabricated system. Results generally indicated lower oxygen level inside wells than on top of wells, and local oxygen level dependence on structural features of cell culture surfaces. Interestingly, chemical composition of cell culture substrates also appeared to affect oxygen level, with type-I collagen based cell culture systems having lower oxygen concentration compared to PDMS based cell culture systems. In general, results suggest that oxygen sensing beads can be utilized to achieve real-time and local monitoring of micro-environment oxygen level in 3D microfabricated cell culture systems.

High pressure oxygen turbopump bearing cage stability analyses. [space shuttle main engine

NASA Technical Reports Server (NTRS)

Merriman, T. L.; Kannel, J. W.

1984-01-01

The low service life of the high pressure oxygen turbopump (HPOTP) bearings used in the space shuttle main engine was examined by use of the Battelle "BASDAP' bearing computer stability model. The dynamic instability of the bearing cage resulted in excessive wear and eventual failure of the unit. By maintaining a cage/race clearance of no more than 0.25 millimeters (0.010 inches), ball/pocket clearance of no less than 0.54 millimeters (0.025 inches), dynamic balancing of the cages, and maintaining adequate lubricant films between the balls and races, cage instability and subsequent bearing degradation can be reduced.

[Game addiction].

PubMed

Mori, Akio; Iwadate, Masako; Minakawa, Nahoko T; Kawashima, Satoshi

2015-09-01

The purpose of this article is to analyze the South Korea and China of computer game research, and the current state of research in Japan. Excessive game actions were analyzed by PET-MRI, MRI, fMRI, NIRS, EEG. These results showed that the prefrontal cortical activity decreased during game play. Also, game addiction causes damage to the prefrontal cortex. The NIRS-EEG and simultaneous recording, during game play correspond well with the decrease of β band and oxygen-hemoglobin. The α band did not change with game play. However, oxygen-hemoglobin decreased during game play. South Korea, game addiction measures have been analyzed since 2002, but in Japan the research is recent.

Relationship between oxygen cost of walking and level of walking disability after stroke: An experimental study.

PubMed

Polese, Janaine C; Ada, Louise; Teixeira-Salmela, Luci F

2018-01-01

Since physical inactivity is the major risk factor for recurrent stroke, it is important to understand how level of disability impacts oxygen uptake by people after stroke. This study investigated the nature of the relationship between level of disability and oxygen cost in people with chronic stroke. Level of walking disability was measured as comfortable walking speed using the 10-m Walk Test reported in m/s with 55 ambulatory people 2 years after stroke. Oxygen cost was measured during 3 walking tasks: overground walking at comfortable speed, overground walking at fast speed, and stair walking at comfortable speed. Oxygen cost was calculated from oxygen uptake divided by distance covered during walking and reported in ml∙kg -1 ∙m -1 . The relationship between level of walking disability and oxygen cost was curvilinear for all 3 walking tasks. One quadratic model accounted for 81% (95% CI [74, 88]) of the variance in oxygen cost during the 3 walking tasks: [Formula: see text] DISCUSSION: The oxygen cost of walking was related the level of walking disability in people with chronic stroke, such that the more disabled the individual, the higher the oxygen cost of walking; with oxygen cost rising sharply as disability became severe. An equation that relates oxygen cost during different walking tasks according to the level of walking disability allows clinicians to determine oxygen cost indirectly without the difficulty of measuring oxygen uptake directly. Copyright © 2017 John Wiley & Sons, Ltd.

Modeling the oxygen microheterogeneity of tumors for photodynamic therapy dosimetry

NASA Astrophysics Data System (ADS)

Pogue, Brian W.; Paulsen, Keith D.; O'Hara, Julia A.; Hoopes, P. Jack; Swartz, Harold

2000-03-01

Photodynamic theory of tumors uses optical excitation of a sensitizing drug within tissue to produce large deposits of singlet oxygen, which are thought to ultimately cause the tumor destruction. Predicting dose deposition of singlet oxygen in vivo is challenging because measurement of this species in vivo is not easily achieved. But it is possible to follow the concentration of oxygen in vivo, and so measuring the oxygen concentration transients during PDT may provide a viable method of estimating the delivered dose of singlet oxygen. However modeling the microscopic heterogeneity of the oxygen distribution within a tumor is non-trivial, and predicting the microscopic dose deposition requires further study, but this study present the framework and initial calibration needed or modeling oxygen transport in complex geometries. Computational modeling with finite elements provides a versatile structure within which oxygen diffusion and consumption can be modeled within realistic tissue geometries. This study develops the basic tools required to simulate a tumor region, and examines the role of (i) oxygen supply and consumption rates, (ii) inter- capillary spacing, (iii) photosensitizer distribution, and (iv) differences between simulated tumors and those derived directly from histology. The result of these calculations indicate that realistic tumor tissue capillary networks can be simulated using the finite element method, without excessive computational burden for 2D regions near 1 mm2, and 3D regions near 0.1mm3. These simulations can provide fundamental information about tissue and ways to implement appropriate oxygen measurements. These calculations suggest that photodynamic therapy produces the majority of singlet oxygen in and near the blood vessels, because these are the sites of highest oxygen tension. These calculations support the concept that tumor vascular regions are the major targets for PDT dose deposition.

Silybin counteracts lipid excess and oxidative stress in cultured steatotic hepatic cells

PubMed Central

Vecchione, Giulia; Grasselli, Elena; Voci, Adriana; Baldini, Francesca; Grattagliano, Ignazio; Wang, David QH; Portincasa, Piero; Vergani, Laura

2016-01-01

AIM: To investigate in vitro the therapeutic effect and mechanisms of silybin in a cellular model of hepatic steatosis. METHODS: Rat hepatoma FaO cells were loaded with lipids by exposure to 0.75 mmol/L oleate/palmitate for 3 h to mimic liver steatosis. Then, the steatotic cells were incubated for 24 h with different concentrations (25 to 100 μmol/L) of silybin as phytosome complex with vitamin E. The effects of silybin on lipid accumulation and metabolism, and on indices of oxidative stress were evaluated by absorption and fluorescence microscopy, quantitative real-time PCR, Western blot, spectrophotometric and fluorimetric assays. RESULTS: Lipid-loading resulted in intracellular triglyceride (TG) accumulation inside lipid droplets, whose number and size increased. TG accumulation was mediated by increased levels of peroxisome proliferator-activated receptors (PPARs) and sterol regulatory element-binding protein-1c (SREBP-1c). The lipid imbalance was associated with higher production of reactive oxygen species (ROS) resulting in increased lipid peroxidation, stimulation of catalase activity and activation of nuclear factor kappa-B (NF-κB). Incubation of steatotic cells with silybin 50 μmol/L significantly reduced TG accumulation likely by promoting lipid catabolism and by inhibiting lipogenic pathways, as suggested by the changes in carnitine palmitoyltransferase 1 (CPT-1), PPAR and SREBP-1c levels. The reduction in fat accumulation exerted by silybin in the steatotic cells was associated with the improvement of the oxidative imbalance caused by lipid excess as demonstrated by the reduction in ROS content, lipid peroxidation, catalase activity and NF-κB activation. CONCLUSION: We demonstrated the direct anti-steatotic and anti-oxidant effects of silybin in steatotic cells, thus elucidating at a cellular level the encouraging results demonstrated in clinical and animal studies. PMID:27468193

Mitochondrial Protein Profile in Mice with Low or Excessive Selenium Diets

PubMed Central

Hu, Lianmei; Wang, Congcong; Zhang, Qin; Yan, Hao; Li, Ying; Pan, Jiaqiang; Tang, Zhaoxin

2016-01-01

Dietary selenium putatively prevents oxidative damage, whereas excessive selenium may lead to animal disorder. In this study, we investigated the effects of low and excessive levels of dietary selenium on oxidative stress and mitochondrial proteins in mouse liver. Six to eight week old mice were fed a diet with low, excessive, or moderate (control) levels of selenium (sodium selenite). The selenium concentration and oxidative stress-related parameters in hepatic mitochondria were evaluated. Two-dimensional electrophoresis and mass spectrometry were applied to identify the differentially-expressed proteins associated with dietary selenium. The selenium content of the livers in mice with the low selenium diet was significantly lower than that of the control, while that of mice fed excessive levels was significantly higher. In both groups oxidative stress in hepatic mitochondria was found; accompanied by lower superoxide dismutase (SOD) and glutathione peroxidase (GPX) levels and higher malondialdehyde (MDA) content, compared with the control group. Furthermore, ten proteins in the hepatic mitochondria of the selenium-low or -excessive groups with more than two-fold differences in abundance compared with the control group were identified. The differentially-expressed proteins in hepatic mitochondria may be associated with dietary (low or excessive) selenium-induced oxidative stress. PMID:27428959

ACE inhibition with captopril retards the development of signs of neurodegeneration in an animal model of Alzheimer's disease.

PubMed

AbdAlla, Said; Langer, Andreas; Fu, Xuebin; Quitterer, Ursula

2013-08-16

Increased generation of reactive oxygen species (ROS) is a significant pathological feature in the brains of patients with Alzheimer's disease (AD). Experimental evidence indicates that inhibition of brain ROS could be beneficial in slowing the neurodegenerative process triggered by amyloid-beta (Abeta) aggregates. The angiotensin II AT1 receptor is a significant source of brain ROS, and AD patients have an increased brain angiotensin-converting enzyme (ACE) level, which could account for an excessive angiotensin-dependent AT1-induced ROS generation. Therefore, we analyzed the impact of ACE inhibition on signs of neurodegeneration of aged Tg2576 mice as a transgenic animal model of AD. Whole genome microarray gene expression profiling and biochemical analyses demonstrated that the centrally active ACE inhibitor captopril normalized the excessive hippocampal ACE activity of AD mice. Concomitantly, the development of signs of neurodegeneration was retarded by six months of captopril treatment. The neuroprotective profile triggered by captopril was accompanied by reduced amyloidogenic processing of the amyloid precursor protein (APP), and decreased hippocampal ROS, which is known to enhance Abeta generation by increased activation of beta- and gamma-secretases. Taken together, our data present strong evidence that ACE inhibition with a widely used cardiovascular drug could interfere with Abeta-dependent neurodegeneration.

ACE Inhibition with Captopril Retards the Development of Signs of Neurodegeneration in an Animal Model of Alzheimer’s Disease

PubMed Central

AbdAlla, Said; Langer, Andreas; Fu, Xuebin; Quitterer, Ursula

2013-01-01

Increased generation of reactive oxygen species (ROS) is a significant pathological feature in the brains of patients with Alzheimer’s disease (AD). Experimental evidence indicates that inhibition of brain ROS could be beneficial in slowing the neurodegenerative process triggered by amyloid-beta (Abeta) aggregates. The angiotensin II AT1 receptor is a significant source of brain ROS, and AD patients have an increased brain angiotensin-converting enzyme (ACE) level, which could account for an excessive angiotensin-dependent AT1-induced ROS generation. Therefore, we analyzed the impact of ACE inhibition on signs of neurodegeneration of aged Tg2576 mice as a transgenic animal model of AD. Whole genome microarray gene expression profiling and biochemical analyses demonstrated that the centrally active ACE inhibitor captopril normalized the excessive hippocampal ACE activity of AD mice. Concomitantly, the development of signs of neurodegeneration was retarded by six months of captopril treatment. The neuroprotective profile triggered by captopril was accompanied by reduced amyloidogenic processing of the amyloid precursor protein (APP), and decreased hippocampal ROS, which is known to enhance Abeta generation by increased activation of beta- and gamma-secretases. Taken together, our data present strong evidence that ACE inhibition with a widely used cardiovascular drug could interfere with Abeta-dependent neurodegeneration. PMID:23959119

Euphorbia factor L1 inhibits osteoclastogenesis by regulating cellular redox status and induces Fas-mediated apoptosis in osteoclast.

PubMed

Hong, Seong-Eun; Lee, Jiae; Seo, Dong-Hyun; In Lee, Hye; Ri Park, Doo; Lee, Gong-Rak; Jo, You-Jin; Kim, Narae; Kwon, Minjung; Shon, Hansem; Kyoung Seo, Eun; Kim, Han-Sung; Young Lee, Soo; Jeong, Woojin

2017-11-01

Excessive bone resorption caused by increased osteoclast number or activity leads to a variety of bone diseases including osteoporosis, rheumatoid arthritis and periodontitis. Thus, the therapeutic strategy for these diseases has been focused primarily on the inhibition of osteoclast formation and function. This study shows that euphorbia factor L1 (EFL1), a diterpenoid isolated from Euphorbia lathyris, inhibited osteoclastogenesis and induced osteoclast apoptosis. EFL1 suppressed osteoclast formation and bone resorption at both initial and terminal differentiation stages. EFL1 inhibited receptor activator of NF-κB ligand (RANKL)-induced NFATc1 induction with attenuated NF-κB activation and c-Fos expression. EFL1 decreased the level of reactive oxygen species by scavenging them or activating Nrf2, and inhibited PGC-1β that regulates mitochondria biogenesis. In addition, EFL1 induced apoptosis in differentiated osteoclasts by increasing Fas ligand expression followed by caspase activation. Moreover, EFL1 inhibited inflammation-induced bone erosion and ovariectomy-induced bone loss in mice. These findings suggest that EFL1 inhibits osteoclast differentiation by regulating cellular redox status and induces Fas-mediated apoptosis in osteoclast, and may provide therapeutic potential for preventing or treating bone-related diseases caused by excessive osteoclast. Copyright © 2017 Elsevier Inc. All rights reserved.

Whole Genome DNA Methylation Analysis of Obstructive Sleep Apnea: IL1R2, NPR2, AR, SP140 Methylation and Clinical Phenotype.

PubMed

Chen, Yung-Che; Chen, Ting-Wen; Su, Mao-Chang; Chen, Chung-Jen; Chen, Kuang-Den; Liou, Chia-Wei; Tang, Petrus; Wang, Ting-Ya; Chang, Jen-Chieh; Wang, Chin-Chou; Lin, Hsin-Ching; Chin, Chien-Hung; Huang, Kuo-Tung; Lin, Meng-Chih; Hsiao, Chang-Chun

2016-04-01

We hypothesized that DNA methylation patterns may contribute to disease severity or the development of hypertension and excessive daytime sleepiness (EDS) in patients with obstructive sleep apnea (OSA). Illumina's (San Diego, CA, USA) DNA methylation 27-K assay was used to identify differentially methylated loci (DML). DNA methylation levels were validated by pyrosequencing. A discovery cohort of 15 patients with OSA and 6 healthy subjects, and a validation cohort of 72 patients with sleep disordered breathing (SDB). Microarray analysis identified 636 DMLs in patients with OSA versus healthy subjects, and 327 DMLs in patients with OSA and hypertension versus those without hypertension. In the validation cohort, no significant difference in DNA methylation levels of six selected genes was found between the primary snoring subjects and OSA patients (primary outcome). However, a secondary outcome analysis showed that interleukin-1 receptor 2 (IL1R2) promoter methylation (-114 cytosine followed by guanine dinucleotide sequence [CpG] site) was decreased and IL1R2 protein levels were increased in the patients with SDB with an oxygen desaturation index > 30. Androgen receptor (AR) promoter methylation (-531 CpG site) and AR protein levels were both increased in the patients with SDB with an oxygen desaturation index > 30. Natriuretic peptide receptor 2 (NPR2) promoter methylation (-608/-618 CpG sites) were decreased, whereas levels of both NPR2 and serum C type natriuretic peptide protein were increased in the SDB patients with EDS. Speckled protein 140 (SP140) promoter methylation (-194 CpG site) was increased, and SP140 protein levels were decreased in the patients with SDB and EDS. IL1R2 hypomethylation and AR hypermethylation may constitute an important determinant of disease severity, whereas NPR2 hypomethylation and SP140 hypermethylation may provide a biomarker for vulnerability to EDS in OSA. A commentary on this article appears in this issue on page 723. © 2016 Associated Professional Sleep Societies, LLC.

Ocean N2O Emissions : Recent Global Estimates and Anthropogenically Influenced Changes

NASA Astrophysics Data System (ADS)

Suntharalingam, P.; Buithenuis, E.; Andrews, O.; Le Quere, C.

2016-12-01

Oceanic N2O is produced by microbial activity during organic matter cycling in the subsurface ocean; its production mechanisms display sensitivity to ambient oxygen level. In the oxic ocean, N2O is produced as a byproduct during the oxidation of ammonia to nitrate, mediated by ammonia oxidizing bacteria and archea. N2O is also produced and consumed in sub-oxic and anoxic waters through the action of marine denitrifiers during the multi-step reduction of nitrate to gaseous nitrogen. The oceanic N2O distribution therefore displays significant heterogeneity with background levels of 10-20 nmol/l in the well-oxygenated ocean basins, high concentrations (> 40 nmol/l) in hypoxic waters, and N2O depletion in the core of ocean oxygen minimum zones (OMZs). Oceanic N2O emissions are estimated to account for up to a third of the pre-industrial N2O fluxes to the atmosphere, however the natural cycle of ocean N2O has been perturbed in recent decades by inputs of anthropogenically derived nutrient, and by the impacts of climate change. Anthropogenic nitrogen inputs (e.g., NOx and NHy from fossil fuel combustion and agricultural fertilizer) enter the ocean via atmospheric deposition and riverine fluxes, influencing oceanic N2O production via their impact on the marine organic matter cycle. In addition, climate variations associated with surface ocean warming affect oceanic circulation and nutrient transport pathways, influencing marine productivity and the ventilation of oxygen minimum zones. Recent studies have suggested that possible expansion of oceanic OMZs in a warming climate could lead to significant changes in N2O production and fluxes from these regions. We will summarise the current state of knowledge on the ocean N2O budget and net flux to the atmosphere. Recently reported estimates have been based on (i) empirical relationships derived from ocean tracer data (e.g., involving excess N2O and Apparent Oxygen Utilization (AOU) correlations), (ii) ocean biogeochemical models, and (iii) air-sea flux calculations which combine surface ocean N2O measurements with gas-exchange relationships. We will also present results from ongoing ocean biogeochemistry model analyses evaluating the separate influences of climate variation and anthropogenic nutrient inputs on ocean N2O emissions for recent decades.

Fat-free mass and excess post-exercise oxygen consumption in the 40 minutes after short-duration exhaustive exercise in young male Japanese athletes.

PubMed

Tahara, Yasuaki; Moji, Kazuhiko; Honda, Sumihisa; Nakao, Rieko; Tsunawake, Noriaki; Fukuda, Rika; Aoyagi, Kiyoshi; Mascie-Taylor, Nicholas

2008-05-01

The relationship between fat-free mass (FFM) and excess post-exercise oxygen consumption (EPOC) has not been well researched because of the relatively small number of subjects studied. This study investigated the effects of FFM on EPOC and EPOC/maximum oxygen consumption. 250 Japanese male athletes between 16 and 21 years old from Nagasaki prefecture had their EPOC measured up to 40 minutes after short-duration exhaustive exercise. The value was named as EPOC40 min. The proportions of EPOC up to 1, 3, 6, 10, and 25 minutes to EPOC40 min were calculated and named as P1, P3, P6, P10, and P25, respectively. Body size and composition, VO2max and resting metabolic rate (RMR) were also measured. Mean EPOC40 min was 9.04 L or 158 ml/kg FFM. EPOC40 min was related to FFM (r=0.55, p<0.001) and VO2max (r=0.37, p<0.001). The ratio of EPOC40 min to VO2max was related to FFM (r=0.28, p<0.001). P1, P3, P6, P10, and P25 were negatively related to EPOC40 min/FFM, EPOC40 min/VO2max, and FFM. Athletes who had larger FFM had larger EPOC40 40 min and EPOC40 40 min/VO2max, and smaller P1, P3, P10, and P25.

Appraisal of water-quality conditions, lower Black River, Windsor County, Vermont

USGS Publications Warehouse

Toppin, K.W.

1983-01-01

Six hydroelectric power dams are planned along a 22-mile reach of the lower Black River in southeastern Windsor County, Vermont. Data were collected at 10 stations, during water years 1977-81, to appraise quality conditions before construction. Average specific conductance of Black River is 101 micromhos indicating low concentrations of dissolved solids. Concentrations of common constituents and minor elements were generally low and within safe levels for aquatic life. Near-saturated dissolved oxygen concentrations and relatively low mean total organic carbon concentrations indicate little oxygen-consuming substances in Black River. Mean total nitrogen concentrations ranged from 0.31 mg/L (milligrams per liter) to 0.61 mg/L. The highest concentrations were most likely due to secondary waste discharges entering the river. Nitrate was the primary form of inorganic nitrogen, mean concentrations ranged from 0.13 to 0.27 mg/L. Concentrations seem high enough to promote excessive algal growth in the proposed Hawks Mountain Reservoir. Mean concentrations of total phosphorus ranged from 0.014 to 0.112 mg/L as P. Maximum concentrations at all stations generally exceeded U.S. Environmental Protection Agency suggested levels for water entering lakes and reservoirs. Mean orthophosphorus concentrations ranged from 0.005 to 0.029 mg/L, suggesting a potential for nuisance algal conditions to develop in the proposed reservoir. Mean algal growth potential concentrations ranged from 1.3 to 8.8 mg/L, falling within the moderately high to high productivity range. No pesticides and polychlorinated biphenyls were detected. (USGS)

Calcium Signaling and Reactive Oxygen Species in Mitochondria.

PubMed

Bertero, Edoardo; Maack, Christoph

2018-05-11

In heart failure, alterations of Na + and Ca 2+ handling, energetic deficit, and oxidative stress in cardiac myocytes are important pathophysiological hallmarks. Mitochondria are central to these processes because they are the main source for ATP, but also reactive oxygen species (ROS), and their function is critically controlled by Ca 2+ During physiological variations of workload, mitochondrial Ca 2+ uptake is required to match energy supply to demand but also to keep the antioxidative capacity in a reduced state to prevent excessive emission of ROS. Mitochondria take up Ca 2+ via the mitochondrial Ca 2+ uniporter, which exists in a multiprotein complex whose molecular components were identified only recently. In heart failure, deterioration of cytosolic Ca 2+ and Na + handling hampers mitochondrial Ca 2+ uptake and the ensuing Krebs cycle-induced regeneration of the reduced forms of NADH (nicotinamide adenine dinucleotide) and NADPH (nicotinamide adenine dinucleotide phosphate), giving rise to energetic deficit and oxidative stress. ROS emission from mitochondria can trigger further ROS release from neighboring mitochondria termed ROS-induced ROS release, and cross talk between different ROS sources provides a spatially confined cellular network of redox signaling. Although low levels of ROS may serve physiological roles, higher levels interfere with excitation-contraction coupling, induce maladaptive cardiac remodeling through redox-sensitive kinases, and cell death through mitochondrial permeability transition. Targeting the dysregulated interplay between excitation-contraction coupling and mitochondrial energetics may ameliorate the progression of heart failure. © 2018 American Heart Association, Inc.

Oxidative Tritium Decontamination System

DOEpatents

Gentile, Charles A. , Guttadora, Gregory L. , Parker, John J.

2006-02-07

The Oxidative Tritium Decontamination System, OTDS, provides a method and apparatus for reduction of tritium surface contamination on various items. The OTDS employs ozone gas as oxidizing agent to convert elemental tritium to tritium oxide. Tritium oxide vapor and excess ozone gas is purged from the OTDS, for discharge to atmosphere or transport to further process. An effluent stream is subjected to a catalytic process for the decomposition of excess ozone to diatomic oxygen. One of two configurations of the OTDS is employed: dynamic apparatus equipped with agitation mechanism and large volumetric capacity for decontamination of light items, or static apparatus equipped with pressurization and evacuation capability for decontamination of heavier, delicate, and/or valuable items.

Hydrogen peroxide production is affected by oxygen levels in mammalian cell culture.

PubMed

Maddalena, Lucas A; Selim, Shehab M; Fonseca, Joao; Messner, Holt; McGowan, Shannon; Stuart, Jeffrey A

2017-11-04

Although oxygen levels in the extracellular space of most mammalian tissues are just a few percent, under standard cell culture conditions they are not regulated and are often substantially higher. Some cellular sources of reactive oxygen species, like NADPH oxidase 4, are sensitive to oxygen levels in the range between 'normal' physiological (typically 1-5%) and standard cell culture (up to 18%). Hydrogen peroxide in particular participates in signal transduction pathways via protein redox modifications, so the potential increase in its production under standard cell culture conditions is important to understand. We measured the rates of cellular hydrogen peroxide production in some common cell lines, including C2C12, PC-3, HeLa, SH-SY5Y, MCF-7, and mouse embryonic fibroblasts (MEFs) maintained at 18% or 5% oxygen. In all instances the rate of hydrogen peroxide production by these cells was significantly greater at 18% oxygen than at 5%. The increase in hydrogen peroxide production at higher oxygen levels was either abolished or substantially reduced by treatment with GKT 137831, a selective inhibitor of NADPH oxidase subunits 1 and 4. These data indicate that oxygen levels experienced by cells in culture influence hydrogen peroxide production via NADPH oxidase 1/4, highlighting the importance of regulating oxygen levels in culture near physiological values. However, we measured pericellular oxygen levels adjacent to cell monolayers under a variety of conditions and with different cell lines and found that, particularly when growing at 5% incubator oxygen levels, pericellular oxygen was often lower and variable. Together, these observations indicate the importance, and difficulty, of regulating oxygen levels experienced by cells in culture. Copyright © 2017 Elsevier Inc. All rights reserved.

Microstructure and Properties of KSr2Nb5O15 Ceramics with Excess K+

NASA Astrophysics Data System (ADS)

Wang, Min; Gao, Feng; Xu, Jie; Zhang, Chaochao; Qin, Mengjie; Wang, Li; Guo, Yiting

2017-03-01

KSr2Nb5O15- xK (KSN- xK, x = 0 mol.%, 4 mol.%, 8 mol.%, 12 mol.%, 16 mol.%, and 20 mol.%) lead-free ferroelectric ceramics have been prepared by a buried sintering method using needle-like KSN particles synthesized by molten salt synthesis, and their microstructure, dielectric properties, and infrared transmittance investigated. The results suggest that the KSN- xK ceramics had simplex tungsten bronze structure for x ≤ 12 mol.%, but K2Nb8O21 secondary phase appeared at higher x. Excess K+ compensated the shortage of A-site ions in KSN crystallites, alleviated lattice distortion, and drove the KSN component closer to stoichiometric ratio, all of which increased the Curie temperature. The dielectric relaxor behavior of the ceramics was enhanced as the excess K+ content was increased. The dielectric constant, dielectric tunability, and infrared transmittance initially increased then decreased with increasing x. The specimen with 12 mol.% excess K+ showed optimum electrical properties, including maximum infrared transmittance of ˜60%. This work confirms that A-site vacancies in KSN can be compensated by excess K+, and that this effect can be used to adjust the local composition, alleviate structural distortion of the oxygen octahedron, enhance the Curie temperature, etc.

Hydrilla verticillata employs two different ways to affect DNA methylation under excess copper stress.

PubMed

Shi, Danlu; Zhuang, Kai; Xia, Yan; Zhu, Changhua; Chen, Chen; Hu, Zhubing; Shen, Zhenguo

2017-12-01

Because of the accumulation of heavy metals, Hydrilla verticillata (L.f.) Royle, a rooted submerged perennial aquatic herb, is being developed as a potential tool to clean the aquatic ecosystem polluted by heavy metals. However, its physiological responses for heavy metal remain to be elucidated. Here, through employing proteomics approach, we found that excess Cu significantly induced the expressions of four DNA methylation related proteins in H. verticillata, which were the homologues of two domains rearranged methyltransferases (DRM), a methyltransferases chromomethylase (CMT) and a histone H3 lysine-9 specific SUVH6-like (SUVH6). Consistently, a dramatic change in DNA methylation patterns was detected in excess Cu-exposed H. verticillata. Surprisingly, administration of the NADPH oxidase inhibitors, diphenylene iodonium (DPI) and imidazole (IMZ) that block production of reactive oxygen species (ROS) could trigger the remethylation of genomic sites that were demethylated by excess Cu, indicating that Cu-induced ROS might be another way to affect DNA methylation. Further analysis suggested this changed DNA methylation may be owing to the ROS-induced DNA damage. Taken together, our findings demonstrate that two different ways to influence DNA methylation in excess Cu-treated H. verticillata. Copyright © 2017 Elsevier B.V. All rights reserved.

Physiological effects of positive pressure breathing with pure oxygen and a low oxygen gas mixture.

PubMed

Liu, Xiaopeng; Xiao, Huajun; Shi, Weiru; Wen, Dongqing; Yu, Lihua; Chen, Jianzhang

2015-01-01

Positive pressure breathing (PPB) can cause circulatory dysfunction due to peripheral pooling of blood. This study explored a better way at ground level to simulate pure oxygen PPB at 59,055 ft (18,000 m) by comparing the physiological changes during PPB with pure oxygen and low oxygen at ground level. Six subjects were exposed to 3 min of 69-mmHg PPB and 3 min of 59-mmHg PPB with pure oxygen and low oxygen while wearing the thoracic counterpressure jerkin inflated to 1× breathing pressure and G-suit inflated to 3 and 4× breathing pressure. Stroke volume (SV), cardiac output (CO), heart rate (HR), and peripheral oxygen saturation (Spo2) were measured. Subjects completed a simulating flying task (SFT) during 3-min PPB and scores were recorded. HR and SV responses differed significantly between breathing pure oxygen and low oxygen. CO response was not significantly different for pure oxygen and low oxygen, the two levels of PPB, and the two levels of G-suit pressure. Spo2 declined as a linear function of time during low-oxygen PPB and there was a significant difference in Spo2 response for the two levels of PPB. The average score of SFT during pure oxygen PPB was 3970.5 ± 1050.4, which was significantly higher than 2708.0 ± 702.7 with low oxygen PPB. Hypoxia and PPB have a synergistic negative effect on both the cardiovascular system and SFT performance. PPB with low oxygen was more appropriate at ground level to investigate physiological responses during PPB and evaluate the protective performance of garments. Liu X, Xiao H, Shi W, Wen D, Yu L, Chen J. Physiological effects of positive pressure breathing with pure oxygen and a low oxygen gas mixture.

Low oxygen level increases proliferation and metabolic changes in bovine granulosa cells.

PubMed

Shiratsuki, Shogo; Hara, Tomotaka; Munakata, Yasuhisa; Shirasuna, Koumei; Kuwayama, Takehito; Iwata, Hisataka

2016-12-05

The present study addresses molecular backgrounds underlying low oxygen induced metabolic changes and 1.2-fold change in bovine granulosa cell (GCs) proliferation. RNA-seq revealed that low oxygen (5%) upregulated genes associated with HIF-1 and glycolysis and downregulated genes associated with mitochondrial respiration than that in high oxygen level (21%). Low oxygen level induced high glycolytic activity and low mitochondrial function and biogenesis. Low oxygen level enhanced GC proliferation with high expression levels of HIF-1, VEGF, AKT, mTOR, and S6RP, whereas addition of anti-VEGF antibody decreased cellular proliferation with low phosphorylated AKT and mTOR expression levels. Low oxygen level reduced SIRT1, whereas activation of SIRT1 by resveratrol increased mitochondrial replication and decreased cellular proliferation with reduction of phosphorylated mTOR. These results suggest that low oxygen level stimulates the HIF1-VEGF-AKT-mTOR pathway and up-regulates glycolysis, which contributes to GC proliferation, and downregulation of SIRT1 contributes to hypoxia-associated reduction of mitochondria and cellular proliferation. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

The Effect of Oxygen Supply on the Dual Growth Kinetics of Acidithiobacillus thiooxidans under Acidic Conditions for Biogas Desulfurization

PubMed Central

Namgung, Hyeong-Kyu; Song, JiHyeon

2015-01-01

In this study, to simulate a biogas desulfurization process, a modified Monod-Gompertz kinetic model incorporating a dissolved oxygen (DO) effect was proposed for a sulfur-oxidizing bacterial (SOB) strain, Acidithiobacillus thiooxidans, under extremely acidic conditions of pH 2. The kinetic model was calibrated and validated using experimental data obtained from a bubble-column bioreactor. The SOB strain was effective for H2S degradation, but the H2S removal efficiency dropped rapidly at DO concentrations less than 2.0 mg/L. A low H2S loading was effectively treated with oxygen supplied in a range of 2%–6%, but a H2S guideline of 10 ppm could not be met, even with an oxygen supply greater than 6%, when the H2S loading was high at a short gas retention time of 1 min and a H2S inlet concentration of 5000 ppm. The oxygen supply should be increased in the aerobic desulfurization to meet the H2S guideline; however, the excess oxygen above the optimum was not effective because of the decline in oxygen efficiency. The model estimation indicated that the maximum H2S removal rate was approximately 400 ppm/%-O2 at the influent oxygen concentration of 4.9% under the given condition. The kinetic model with a low DO threshold for the interacting substrates was a useful tool to simulate the effect of the oxygen supply on the H2S removal and to determine the optimal oxygen concentration. PMID:25633028

Monitoring Intracellular Oxygen Concentration: Implications for Hypoxia Studies and Real-Time Oxygen Monitoring.

PubMed

Potter, Michelle; Badder, Luned; Hoade, Yvette; Johnston, Iain G; Morten, Karl J

2016-01-01

The metabolic properties of cancer cells have been widely accepted as a hallmark of cancer for a number of years and have shown to be of critical importance in tumour development. It is generally accepted that tumour cells exhibit a more glycolytic phenotype than normal cells. In this study, we investigate the bioenergetic phenotype of two widely used cancer cell lines, RD and U87MG, by monitoring intracellular oxygen concentrations using phosphorescent Pt-porphyrin based intracellular probes. Our study demonstrates that cancer cell lines do not always exhibit an exclusively glycolytic phenotype. RD demonstrates a reliance on oxidative phosphorylation whilst U87MG display a more glycolytic phenotype. Using the intracellular oxygen sensing probe we generate an immediate readout of intracellular oxygen levels, with the glycolytic lines reflecting the oxygen concentration of the environment, and cells with an oxidative phenotype having significantly lower levels of intracellular oxygen. Inhibition of oxygen consumption in lines with high oxygen consumption increases intracellular oxygen levels towards environmental levels. We conclude that the use of intracellular oxygen probes provides a quantitative assessment of intracellular oxygen levels, allowing the manipulation of cellular bioenergetics to be studied in real time.

Method and apparatus for producing oxygen and nitrogen and membrane therefor

DOEpatents

Roman, I.C.; Baker, R.W.

1985-09-17

Process and apparatus for the separation and purification of oxygen and nitrogen as well as a novel membrane useful therein are disclosed. The process utilizes novel facilitated transport membranes to selectively transport oxygen from one gaseous stream to another, leaving nitrogen as a byproduct. In the method, an oxygen carrier capable of reversibly binding molecular oxygen is dissolved in a polar organic membrane which separates a gaseous feed stream such as atmospheric air and a gaseous product stream. The feed stream is maintained at a sufficiently high oxygen pressure to keep the oxygen carrier in its oxygenated form at the interface of the feed stream with the membrane, while the product stream is maintained at a sufficiently low oxygen pressure to keep the carrier in its deoxygenated form at the interface of the product stream with the membrane. In an alternate mode of operation, the feed stream is maintained at a sufficiently low temperature and high oxygen pressure to keep the oxygen carrier in its oxygenated form at the interface of the feed stream with the membrane and the product stream is maintained at a sufficiently high temperature to keep the carrier in its deoxygenated form at the interface of the product stream with the membrane. Under such conditions, the carrier acts as a shuttle, picking up oxygen at the feed side of the membrane, diffusing across the membrane as the oxygenated complex, releasing oxygen to the product stream, and then diffusing back to the feed side to repeat the process. Exceptionally and unexpectedly high O[sub 2]/N[sub 2] selectivity, on the order of 10 to 30, is obtained, as well as exceptionally high oxygen permeability, on the order of 6 to 15 [times] 10[sup [minus]8] cm[sup 3]-cm/cm[sup 2]-sec-cmHg, as well as a long membrane life of in excess of 3 months, making the process commercially feasible. 2 figs.

Method and apparatus for producing oxygen and nitrogen and membrane therefor

DOEpatents

Roman, Ian C.; Baker, Richard W.

1985-01-01

Process and apparatus for the separation and purification of oxygen and nitrogen as well as a novel membrane useful therein are disclosed. The process utilizes novel facilitated transport membranes to selectively transport oxygen from one gaseous stream to another, leaving nitrogen as a byproduct. In the method, an oxygen carrier capable of reversibly binding molecular oxygen is dissolved in a polar organic membrane which separates a gaseous feed stream such as atmospheric air and a gaseous product stream. The feed stream is maintained at a sufficiently high oxygen pressure to keep the oxygen carrier in its oxygenated form at the interface of the feed stream with the membrane, while the product stream is maintained at a sufficiently low oxygen pressure to keep the carrier in its deoxygenated form at the interface of the product stream with the membrane. In an alternate mode of operation, the feed stream is maintained at a sufficiently low temperature and high oxygen pressure to keep the oxygen carrier in its oxygenated form at the interface of the feed stream with the membrane and the product stream is maintained at a sufficiently high temperature to keep the carrier in its deoxygenated form at the interface of the product stream with the membrane. Under such conditions, the carrier acts as a shuttle, picking up oxygen at the feed side of the membrane, diffusing across the membrane as the oxygenated complex, releasing oxygen to the product stream, and then diffusing back to the feed side to repeat the process. Exceptionally and unexpectedly high O.sub.2 /N.sub.2 selectivity, on the order of 10 to 30, is obtained, as well as exceptionally high oxygen permeability, on the order of 6 to 15.times.10.sup.-8 cm.sup.3 -cm/cm.sup.2 -sec-cmHg, as well as a long membrane life of in excess of 3 months, making the process commercially feasible.

Impact of sub-keV soft excess on warm absorbers

NASA Astrophysics Data System (ADS)

Chakravorty, S.

2009-09-01

Soft X-ray spectral features of warm absorbers (WA) are often found in Seyfert 1 galaxies. The ionizing continuum coming from the central engine and which photoionizes the WA, can be optimally modeled to have three spectral components a) the 'disk blackbody' at about 10 eV - the spectrum from the accretion disk of the black hole, b) the X-ray powerlaw - representing the dominant component at energies 1 keV and above and c) the soft excess in sub keV - which is seen in most objects after deducting the powerlaw component. We use the thermal equilibrium curves generated by the photoionization code CLOUDY to study the influence of the soft excess component on the nature of the WA. Our studies show that the nature of the WA is strongly dependent on the chemical composition of the absorbing gas, particularly on the abundance of iron, oxygen and the X-ray group (C, Ne, O, Fe) which have important atomic transitions in the energy range 0.3 - 1.5 keV where the soft excess component is supposed to have maximum effect. One of the popular models for the soft excess component is a blackbody with its temperature lying between 100 - 200 eV. We find that the soft excess component seems to decide the stability properties of the gas at 10^5 K; the range of xi/T over which stable warm absorber exists almost doubles if the soft excess luminosity is equal to the luminosity in the powerlaw (0.1 - 10 keV) which is a ratio not unheard of. Even if the soft excess is represented using alternative spectral shapes like the 'comptonized reflection' model, the stability properties of the WA do not change significantly.

The potential for chemical evolution on Titan

NASA Technical Reports Server (NTRS)

Beauchamp, P. M.; Lunine, J. I.; Welch, C.

2002-01-01

Sampling of organics to determine oxygen content, extent of acetylene polymerization, existence of chiral molecules and enantiomeric excesses, and searches for specific polymer products, would be of interest in assessing how organic chemistry evolves toward biochemistry. Such efforts would require fairly sophisticated chemical analyses from landed missions. This paper examines this chemistry and the potential instruments that could distinguish chemical evolution.

Plasma Jet Interactions with Liquids in Partial Fulfillment of an NRL Karles Fellowship

DTIC Science & Technology

2015-11-30

water (DI H2O) as the reference solution, two concentrations of NaCl mixtures (0.6 Molar, and 1.0 Molar saturated NaCl), and three electroless solutions...by diffusion) to the bulk surface in net excess; that oxygen ions/radicals are being consumed from the bulk by an electrolysis path way; or that the

Earth, wind, and fire: Abiotic factors and the impacts of global environmental change on forest health

Treesearch

J.E. Lundquist; A.E. Camp; M.L. Tyrell; S.J. Seybold; P. Cannon; D.J. Lodge

2011-01-01

Trees do not just die; there is always a primary cause, and often contributing factors. Trees need adequate quantities of water, heat, light, nutrients, carbon dioxide, oxygen, and other abiotic resources to sustain life, growth, and reproduction. When these factors are deficient or excessive, they cause mortality. According to the concept of baseline mortality (...

Role of Magnesium in Oxidative Stress in Individuals with Obesity.

PubMed

Morais, Jennifer Beatriz Silva; Severo, Juliana Soares; Santos, Loanne Rocha Dos; de Sousa Melo, Stéfany Rodrigues; de Oliveira Santos, Raisa; de Oliveira, Ana Raquel Soares; Cruz, Kyria Jayanne Clímaco; do Nascimento Marreiro, Dilina

2017-03-01

Adipose tissue is considered an endocrine organ that promotes excessive production of reactive oxygen species when in excess, thus contributing to lipid peroxidation. Magnesium deficiency contributes to the development of oxidative stress in obese individuals, as this mineral plays a role as an antioxidant, participates as a cofactor of several enzymes, maintains cell membrane stability and mitigates the effects of oxidative stress. The objective of this review is to bring together updated information on the participation of magnesium in the oxidative stress present in obesity. We conducted a search of articles published in the PubMed, SciELO and LILACS databases, using the keywords 'magnesium', 'oxidative stress', 'malondialdehyde', 'superoxide dismutase', 'glutathione peroxidase', 'reactive oxygen species', 'inflammation' and 'obesity'. The studies show that obese subjects have low serum concentrations of magnesium, as well as high concentrations of oxidative stress marker in these individuals. Furthermore, it is evident that the adequate intake of magnesium contributes to its appropriate homeostasis in the body. Thus, this review of current research can help define the need for intervention with supplementation of this mineral for the prevention and treatment of disorders associated with this chronic disease.

Charge doping and large lattice expansion in oxygen-deficient heteroepitaxial WO3

NASA Astrophysics Data System (ADS)

Mattoni, Giordano; Filippetti, Alessio; Manca, Nicola; Zubko, Pavlo; Caviglia, Andrea D.

2018-05-01

Tungsten trioxide (WO3) is a versatile material with widespread applications ranging from electrochromics and optoelectronics to water splitting and catalysis of chemical reactions. For technological applications, thin films of WO3 are particularly appealing, taking advantage from a high surface-to-volume ratio and tunable physical properties. However, the growth of stoichiometric crystalline thin films is challenging because the deposition conditions are very sensitive to the formation of oxygen vacancies. In this paper, we show how background oxygen pressure during pulsed laser deposition can be used to tune the structural and electronic properties of WO3 thin films. By performing x-ray diffraction and low-temperature electrical transport measurements, we find changes in the WO3 lattice volume of up to 10% concomitantly with a resistivity drop of more than five orders of magnitude at room temperature as a function of increased oxygen deficiency. We use advanced ab initio calculations to describe in detail the properties of the oxygen vacancy defect states and their evolution in terms of excess charge concentration. Our results depict an intriguing scenario where structural, electronic, optical, and transport properties of WO3 single-crystal thin films can all be purposely tuned by controlling the oxygen vacancy formation during growth.

Texturing Carbon-carbon Composite Radiator Surfaces Utilizing Atomic Oxygen

NASA Technical Reports Server (NTRS)

Raack, Taylor

2004-01-01

Future space nuclear power systems will require radiator technology to dissipate excess heat created by a nuclear reactor. Large radiator fins with circulating coolant are in development for this purpose and an investigation of how to make them most efficient is underway. Maximizing the surface area while minimizing the mass of such radiator fins is critical for obtaining the highest efficiency in dissipating heat. Processes to develop surface roughness are under investigation to maximize the effective surface area of a radiator fin. Surface roughness is created through several methods including oxidation and texturing. The effects of atomic oxygen impingement on carbon-carbon surfaces are currently being investigated for texturing a radiator surface. Early studies of atomic oxygen impingement in low Earth orbit indicate significant texturing due to ram atomic oxygen. The surface morphology of the affected surfaces shows many microscopic cones and valleys which have been experimentally shown to increase radiation emittance. Further study of this morphology proceeded in the Long Duration Exposure Facility (LDEF). Atomic oxygen experiments on the LDEF successfully duplicated the results obtained from materials in spaceflight by subjecting samples to 4.5 eV atomic oxygen from a fixed ram angle. These experiments replicated the conical valley morphology that was seen on samples subjected to low Earth orbit.

Oxygen partial pressure effects on metabolic rate and behavior of tethered flying locusts.

PubMed

Rascón, Brenda; Harrison, Jon F

2005-11-01

Resting insects are extremely tolerant of hypoxia. However, oxygen requirements increase dramatically during flight. Does the critical atmospheric P (O)(2) (P(c)) increase strongly during flight, or does increased tracheal conductance allow even flying insects to possess large safety margins for oxygen delivery? We tested the effect of P(O)(2) on resting and flying CO(2) emission, as well as on flight behavior and vertical force production in flying locusts, Schistocerca americana. The P(c) for CO(2) emission of resting animals was less than 1 kPa, similar to prior studies. The P(c) for flight bout duration was between 10 and 21 kPa, the P(c) for vertical force production was between 3 and 5 kPa, and the P(c) for CO(2) emission was between 10 and 21 kPa. Our study suggests that the P(c) for steady-state oxygen consumption is between 10 and 21 kPa (much higher than for resting animals), and that tracheal oxygen stores allowed brief flights in 5 and 10 kPa P(O)(2) atmospheres to occur. Thus, P(c) values strongly increased during flight, consistent with the hypothesis that the excess oxygen delivery capacity observed in resting insects is substantially reduced during flight.

Interaction of plasmalogens and their diacyl analogs with singlet oxygen in selected model systems

PubMed Central

Broniec, Agnieszka; Klosinski, Radoslaw; Pawlak, Anna; Wrona-Krol, Marta; Thompson, David; Sarna, Tadeusz

2011-01-01

Plasmalogens (Plg) are phospholipids containing vinyl ether linkage at the sn-1 position of the glycerophospholipid backbone. In spite of being quite abundant in humans, the biological role of plasmalogens remains speculative. It has been postulated that plasmalogens are physiological antioxidants with the vinyl ether functionality serving as sacrificial trap for free radicals and singlet oxygen. However, no quantitative data on the efficiency of plasmalogens to scavenge these reactive species are available. In this study, rate constants of quenching of singlet oxygen, generated by photosensitized energy transfer, by several plasmalogens and, for comparison, by their diacyl analogs, were determined by time-resolved detection of phosphorescence at 1270 nm. Relative rates of the interaction of singlet oxygen, with plasmalogens and other lipids in solution and liposomal membranes were measured by electron paramagnetic resonance oximetry and product analysis, employing HPLC-EC detection of cholesterol hydroperoxides and iodometric assay of lipid hydroperoxides. Results show that singlet oxygen interacts with plasmalogens significantly faster than with the other lipids, with he corresponding rate constants being by one-two orders of magnitude greater. The quenching of singlet oxygen by plasmalogens is mostly reactive in nature and results from its preferential interaction with the vinyl ether bond. The data suggest that plasmalogens could protect unsaturated membrane lipids against oxidation induced by singlet oxygen, providing that the oxidation products are not excessively cytotoxic. PMID:21236336

Singlet Oxygen Scavenging Activity and Cytotoxicity of Essential Oils from Rutaceae

PubMed Central

Ao, Yoko; Satoh, Kazue; Shibano, Katsushige; Kawahito, Yukari; Shioda, Seiji

2008-01-01

Since we have been exposed to excessive amounts of stressors, aromatherapy for the relaxation has recently become very popular recently. However, there is a problem which responds to light with the essential oil used by aromatherapy. It is generally believed that singlet oxygen is implicated in the pathogenesis of various diseases such as light-induced skin disorders and inflammatory responses. Here we studied whether essential oils can effectively scavenge singlet oxygen upon irradiation, using the electron spin resonance (ESR) method. Green light was used to irradiate twelve essential oils from rutaceae. Among these twelve essential oils, eight were prepared by the expression (or the compression) method (referred to as E oil), and four samples were prepared by the steam distillation method (referred to as SD oil). Five E oils enhanced singlet oxygen production. As these essential oils may be phototoxic, it should be used for their use whit light. Two E oils and three SD oils showed singlet oxygen scavenging activity. These results may suggest that the antioxidant activity of essential oils are judged from their radical scavenging activity. Essential oils, which enhance the singlet oxygen production and show higher cytotoxicity, may contain much of limonene. These results suggest that limonene is involved not only in the enhancement of singlet oxygen production but also in the expression of cytotoxic activity, and that attention has to be necessary for use of blended essential oils. PMID:18648659

Single-cell imaging of bioenergetic responses to neuronal excitotoxicity and oxygen and glucose deprivation.

PubMed

Connolly, Niamh M C; Düssmann, Heiko; Anilkumar, Ujval; Huber, Heinrich J; Prehn, Jochen H M

2014-07-30

Excitotoxicity is a condition occurring during cerebral ischemia, seizures, and chronic neurodegeneration. It is characterized by overactivation of glutamate receptors, leading to excessive Ca(2+)/Na(+) influx into neurons, energetic stress, and subsequent neuronal injury. We and others have previously investigated neuronal populations to study how bioenergetic parameters determine neuronal injury; however, such experiments are often confounded by population-based heterogeneity and the contribution of effects of non-neuronal cells. Hence, we here characterized bioenergetics during transient excitotoxicity in rat and mouse primary neurons at the single-cell level using fluorescent sensors for intracellular glucose, ATP, and activation of the energy sensor AMP-activated protein kinase (AMPK). We identified ATP depletion and recovery to energetic homeostasis, along with AMPK activation, as surprisingly rapid and plastic responses in two excitotoxic injury paradigms. We observed rapid recovery of neuronal ATP levels also in the absence of extracellular glucose, or when glycolytic ATP production was inhibited, but found mitochondria to be critical for fast and complete energetic recovery. Using an injury model of oxygen and glucose deprivation, we identified a similarly rapid bioenergetics response, yet with incomplete ATP recovery and decreased AMPK activity. Interestingly, excitotoxicity also induced an accumulation of intracellular glucose, providing an additional source of energy during and after excitotoxicity-induced energy depletion. We identified this to originate from extracellular, AMPK-dependent glucose uptake and from intracellular glucose mobilization. Surprisingly, cells recovering their elevated glucose levels faster to baseline survived longer, indicating that the plasticity of neurons to adapt to bioenergetic challenges is a key indicator of neuronal viability. Copyright © 2014 the authors 0270-6474/14/3410192-14$15.00/0.

Impact of accelerated future global mean sea level rise on hypoxia in the Baltic Sea

NASA Astrophysics Data System (ADS)

Meier, H. E. M.; Höglund, A.; Eilola, K.; Almroth-Rosell, E.

2017-07-01

Expanding hypoxia is today a major threat for many coastal seas around the world and disentangling its drivers is a large challenge for interdisciplinary research. Using a coupled physical-biogeochemical model we estimate the impact of past and accelerated future global mean sea level rise (GSLR) upon water exchange and oxygen conditions in a semi-enclosed, shallow sea. As a study site, the Baltic Sea was chosen that suffers today from eutrophication and from dead bottom zones due to (1) excessive nutrient loads from land, (2) limited water exchange with the world ocean and (3) perhaps other drivers like global warming. We show from model simulations for the period 1850-2008 that the impacts of past GSLR on the marine ecosystem were relatively small. If we assume for the end of the twenty-first century a GSLR of +0.5 m relative to today's mean sea level, the impact on the marine ecosystem may still be small. Such a GSLR corresponds approximately to the projected ensemble-mean value reported by the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. However, we conclude that GSLR should be considered in future high-end projections (>+1 m) for the Baltic Sea and other coastal seas with similar hydrographical conditions as in the Baltic because GSLR may lead to reinforced saltwater inflows causing higher salinity and increased vertical stratification compared to present-day conditions. Contrary to intuition, reinforced ventilation of the deep water does not lead to overall improved oxygen conditions but causes instead expanded dead bottom areas accompanied with increased internal phosphorus loads from the sediments and increased risk for cyanobacteria blooms.

Measurement of Reactive Oxygen Species in the Culture Media Using Acridan Lumigen PS-3 Assay

PubMed Central

Uy, Benedict; McGlashan, Susan R.; Shaikh, Shamim B.

2011-01-01

Reactive oxygen species (ROS) are generated continuously during aerobic metabolism. ROS are highly reactive molecules and in excessive amounts, can lead to protein and DNA oxidation, protein cross-linking, and cell death. Cell-culture models provide a valuable tool in understanding the mechanisms that lead to cell death. Accumulation of ROS within cells and/or their release into the culture media are highly cell type-specific. The ability to estimate ROS levels in the culture media is an important step in understanding the mechanisms contributing to disease processes. In this paper, we describe the optimization of a simple method to estimate ROS levels in the culture media using the Acridan Lumigen PS-3 reagent provided in the Amersham ECL Plus kit (GE Healthcare, UK). We have shown that the Acridan Lumigen PS-3 assay generates ROS-specific chemiluminescence in fresh as well as media stored at −20°C, in as little as 10–20 μl of samples. The method was able to detect the dose (of stimulants)- and time (acute and chronic)-dependent changes in ROS levels in media collected from various cell types. Our results suggest that the kit reagents, PBS buffer, and various media did not contribute significantly to the overall chemiluminescence generated in the assay; however, we suggest that the unused medium specific for each cell type should be used as blanks and final readings of test samples normalized against these readings. As this method uses commonly available laboratory equipment and commercially available reagents, we believe this assay is convenient, economical, and specific in estimating ROS released extracellularly into the culture media. PMID:21966257

Measurement of reactive oxygen species in the culture media using Acridan Lumigen PS-3 assay.

PubMed

Uy, Benedict; McGlashan, Susan R; Shaikh, Shamim B

2011-09-01

Reactive oxygen species (ROS) are generated continuously during aerobic metabolism. ROS are highly reactive molecules and in excessive amounts, can lead to protein and DNA oxidation, protein cross-linking, and cell death. Cell-culture models provide a valuable tool in understanding the mechanisms that lead to cell death. Accumulation of ROS within cells and/or their release into the culture media are highly cell type-specific. The ability to estimate ROS levels in the culture media is an important step in understanding the mechanisms contributing to disease processes. In this paper, we describe the optimization of a simple method to estimate ROS levels in the culture media using the Acridan Lumigen PS-3 reagent provided in the Amersham ECL Plus kit (GE Healthcare, UK). We have shown that the Acridan Lumigen PS-3 assay generates ROS-specific chemiluminescence in fresh as well as media stored at -20°C, in as little as 10-20 μl of samples. The method was able to detect the dose (of stimulants)- and time (acute and chronic)-dependent changes in ROS levels in media collected from various cell types. Our results suggest that the kit reagents, PBS buffer, and various media did not contribute significantly to the overall chemiluminescence generated in the assay; however, we suggest that the unused medium specific for each cell type should be used as blanks and final readings of test samples normalized against these readings. As this method uses commonly available laboratory equipment and commercially available reagents, we believe this assay is convenient, economical, and specific in estimating ROS released extracellularly into the culture media.

Evaluation of mixed valent iron oxides as reactive adsorbents for arsenic removal.

PubMed

Mishra, Dhananjay; Farrell, James

2005-12-15

The objective of this research was to determine if Fe(II)-bearing iron oxides generate ferric hydroxides at sufficient rates for removing low levels of arsenic in packed-bed reactors, while at the same time avoiding excessive oxide production that contributes to bed clogging in oxygenated waters. Column experiments were performed to determine the effectiveness of three media for arsenic removal over a range in empty bed contact times, influent arsenic concentrations, dissolved oxygen (DO) levels, and solution pH values. Corrosion rates of the media as a function of the water composition were determined using batch and electrochemical methods. Rates of arsenic removal were first order in the As(V) concentration and were greater for media with higher corrosion rates. As(V) removal increased with increasing DO levels primarily due to faster oxidation of the Fe2+ released by media corrosion. To obtain measurable amounts of arsenic removal in 15 mM NaCl electrolyte solutions containing 50 microg/L As(V), the rate of Fe2+ released by the media needed to be at least 15 times greater than the As(V) feed rate into the column. In waters containing 30 mg/L of silica and 50 microg/L of As(V), measurable amounts of arsenic removal were obtained only for Fe2+ release rates that were at least 200 times greater than the As(V) feed rate. Although all columns showed losses in hydraulic conductivity overthe course of 90 days of operation, the conductivity values remained high, and the losses could be reversed by backwashing the media. The reaction products produced by the media in domestic tap water had average As-to-Fe ratios that were approximately 25% higher than those for a commercially available adsorbent.

Adrenal hyperandrogenism is induced by fetal androgen excess in a rhesus monkey model of polycystic ovary syndrome.

PubMed

Zhou, Rao; Bird, Ian M; Dumesic, Daniel A; Abbott, David H

2005-12-01

Adrenal androgen excess is found in approximately 25-60% of women with polycystic ovary syndrome (PCOS), but the mechanisms underlying PCOS-related adrenal androgen excess are unclear. The objective of this study was to determine whether adrenal androgen excess is manifest in a nonhuman primate model for PCOS. Six prenatally androgenized (PA) and six control female rhesus monkeys of similar age, body weight, and body mass index were studied during d 2-6 of two menstrual cycles or anovulatory 30-d periods. Predexamethasone adrenal steroid levels were assessed in the first cycle (cycle 1). In a subsequent cycle (cycle 2), occurring one to three cycles after cycle 1, adrenal steroids were determined 14.5-16.0 h after an i.m. injection of 0.5 mg/kg dexamethasone (postdexamethasone levels) and after an i.v. injection of 50 microg ACTH-(1-39). Both before and after dexamethasone, serum levels of dehydroepiandrosterone (DHEA) in PA females exceeded those in controls. After ACTH injection, PA females exhibited higher circulating levels of DHEA, androstenedione, and corticosterone but comparable levels of 17alpha-hydroxyprogesterone, cortisol, the sulfoconjugate of DHEA, and testosterone compared with controls. Enhanced basal and ACTH-stimulated adrenal androgen levels in PA female monkeys may reflect up-regulation of 17,20 lyase activity in the adrenal zona reticularis, causing adrenal androgen excess comparable with that found in PCOS women with adrenal androgen excess. These findings open the possibility that PCOS adrenal hyperandrogenism may have its origins in fetal androgen excess reprogramming of adrenocortical function.

Pulsed source of energetic atomic oxygen

NASA Technical Reports Server (NTRS)

Caledonia, George E.; Krech, Robert H.

1987-01-01

A pulsed high flux source of nearly monoenergetic atomic oxygen was designed, built, and successfully demonstrated. Molecular oxygen at several atmospheres pressure is introduced into an evacuated supersonic expansion nozzle through a pulsed molecular beam valve. An 18 J pulsed CO2 TEA laser is focused to intensities greater than 10(9) W/sq cm in the nozzle throat to generate a laser-induced breakdown. The resulting plasma is heated in excess of 20,000 K by a laser supported detonation wave, and then rapidly expands and cools. Nozzle geometry confines the expansion to provide rapid electron-ion recombination into atomic oxygen. Average O atom beam velocities from 5 to 13 km/s were measured at estimated fluxes to 10(18) atoms per pulse. Preliminary materials testing has produced the same surface oxygen enrichment in polyethylene samples as obtained on the STS-8 mission. Scanning electron microscope examinations of irradiated polymer surfaces reveal an erosion morphology similar to that obtained in low Earth orbit, with an estimated mass removal rate of approx. 10(-24) cu cm/atom. The characteristics of the O atom source and the results of some preliminary materials testing studies are reviewed.

Molecular Dynamics Simulations of Hydration Effects on Solvation, Diffusivity, and Permeability in Chitosan/Chitin Films.

PubMed

McDonnell, Marshall T; Greeley, Duncan A; Kit, Kevin M; Keffer, David J

2016-09-01

The effects of hydration on the solvation, diffusivity, solubility, and permeability of oxygen molecules in sustainable, biodegradable chitosan/chitin food packaging films were studied via molecular dynamics and confined random walk simulations. With increasing hydration, the membrane has a more homogeneous water distribution with the polymer chains being fully solvated. The diffusivity increased by a factor of 4 for oxygen molecules and by an order of magnitude for water with increasing the humidity. To calculate the Henry's constant and solubility of oxygen in the membranes with changing hydration, the excess chemical potential was calculated via free energy perturbation, thermodynamic integration and direct particle deletion methods. The simulations predicted a higher solubility and permeability for the lower humidity, in contradiction to experimental results. All three methods for calculating the solubility were in good agreement. It was found that the Coulombic interactions in the potential caused the oxygen to bind too strongly to the protonated amine group. Insight from this work will help guide molecular modeling of chitosan/chitin membranes, specifically permeability measurements for small solute molecules. Efforts to chemically tailor chitosan/chitin membranes to favor discrete as opposed to continuous aqueous domains could reduce oxygen permeability.

Supplementation with vitamin A enhances oxidative stress in the lungs of rats submitted to aerobic exercise.

PubMed

Gasparotto, Juciano; Petiz, Lyvia Lintzmaier; Girardi, Carolina Saibro; Bortolin, Rafael Calixto; de Vargas, Amanda Rodrigues; Henkin, Bernardo Saldanha; Chaves, Paloma Rodrigues; Roncato, Sabrina; Matté, Cristiane; Zanotto-Filho, Alfeu; Moreira, José Cláudio Fonseca; Gelain, Daniel Pens

2015-12-01

Exercise training induces reactive oxygen species production and low levels of oxidative damage, which are required for induction of antioxidant defenses and tissue adaptation. This process is physiological and essential to improve physical conditioning and performance. During exercise, endogenous antioxidants are recruited to prevent excessive oxidative stress, demanding appropriate intake of antioxidants from diet or supplements; in this context, the search for vitamin supplements that enhance the antioxidant defenses and improve exercise performance has been continuously increasing. On the other hand, excess of antioxidants may hinder the pro-oxidant signals necessary for this process of adaptation. The aim of this study was to investigate the effects of vitamin A supplementation (2000 IU/kg, oral) upon oxidative stress and parameters of pro-inflammatory signaling in lungs of rats submitted to aerobic exercise (swimming protocol). When combined with exercise, vitamin A inhibited biochemical parameters of adaptation/conditioning by attenuating exercise-induced antioxidant enzymes (superoxide dismutase and glutathione peroxidase) and decreasing the content of the receptor for advanced glycation end-products. Increased oxidative damage to proteins (carbonylation) and lipids (lipoperoxidation) was also observed in these animals. In sedentary animals, vitamin A decreased superoxide dismutase and increased lipoperoxidation. Vitamin A also enhanced the levels of tumor necrosis factor alpha and decreased interleukin-10, effects partially reversed by aerobic training. Taken together, the results presented herein point to negative effects associated with vitamin A supplementation at the specific dose here used upon oxidative stress and pro-inflammatory cytokines in lung tissues of rats submitted to aerobic exercise.

Copper and Iron Homeostasis in Plants: The Challenges of Oxidative Stress

PubMed Central

Pilon, Marinus

2013-01-01

Abstract Significance: Photosynthesis, the process that drives life on earth, relies on transition metal (e.g., Fe and Cu) containing proteins that participate in electron transfer in the chloroplast. However, the light reactions also generate high levels of reactive oxygen species (ROS), which makes metal use in plants a challenge. Recent Advances: Sophisticated regulatory networks govern Fe and Cu homeostasis in response to metal ion availability according to cellular needs and priorities. Molecular remodeling in response to Fe or Cu limitation leads to its economy to benefit photosynthesis. Fe toxicity is prevented by ferritin, a chloroplastic Fe-storage protein in plants. Recent studies on ferritin function and regulation revealed the interplay between iron homeostasis and the redox balance in the chloroplast. Critical Issues: Although the connections between metal excess and ROS in the chloroplast are established at the molecular level, the mechanistic details and physiological significance remain to be defined. The causality/effect relationship between transition metals, redox signals, and responses is difficult to establish. Future Directions: Integrated approaches have led to a comprehensive understanding of Cu homeostasis in plants. However, the biological functions of several major families of Cu proteins remain unclear. The cellular priorities for Fe use under deficiency remain largely to be determined. A number of transcription factors that function to regulate Cu and Fe homeostasis under deficiency have been characterized, but we have not identified regulators that mediate responses to excess. Importantly, details of metal sensing mechanisms and cross talk to ROS-sensing mechanisms are so far poorly documented in plants. Antioxid. Redox Signal. 19, 919–932. PMID:23199018

The formation of diethyl ether via the reaction of iodoethane with atomic oxygen on the Ag(110) surface

NASA Astrophysics Data System (ADS)

Jones, G. Scott; Barteau, Mark A.; Vohs, John M.

1999-01-01

The reactions of iodoethane (ICH 2CH 3) on clean and oxygen-covered Ag(110) surfaces were investigated using temperature-programmed desorption (TPD) and high-resolution electron energy-loss spectroscopy (HREELS). Iodoethane adsorbs dissociatively at 150 K to produce surface ethyl groups on both clean and oxygen-covered Ag(110) surfaces. The ethyl species couple to form butane on both surfaces, with the desorption peak maximum located between 218 and 238 K, depending on the ethyl coverage. In addition to butane, a number of oxidation products including diethyl ether, ethanol, acetaldehyde, surface acetate, ethylene, carbon dioxide and water were formed on the oxygen-dosed Ag(110) surface. Diethyl ether was the major oxygenate produced at all ethyl:oxygen ratios, and the peak temperature for ether evolution varied from 220 to 266 K depending on the relative coverages of these reactants. The total combustion products, CO 2 and H 2O, were primarily formed at low ethyl coverages in the presence of excess oxygen. The formation of ethylene near 240 K probably involves an oxygen-assisted dehydrogenation pathway since ethylene is not formed from ethyl groups on the clean surface. Acetaldehyde and ethanol evolve coincidentally with a peak centered at 270-280 K, and are attributed to the reactions of surface ethoxide species. The surface acetate which decomposes near 620 K is formed from subsequent reactions of acetaldehyde with oxygen atoms. The addition of ethyl to oxygen to form surface ethoxides was verified by HREELS results. The yields of all products exhibited a strong dependence on the relative coverages of ethyl and oxygen.

Enzymatic glucose sensor compensation for variations in ambient oxygen concentration

NASA Astrophysics Data System (ADS)

Collier, Bradley B.; McShane, Michael J.

2013-02-01

Due to the increasing prevalence of diabetes, research toward painless glucose sensing continues. Oxygen sensitive phosphors with glucose oxidase (GOx) can be used to determine glucose levels indirectly by monitoring oxygen consumption. This is an attractive combination because of its speed and specificity. Packaging these molecules together in "smart materials" for implantation will enable non-invasive glucose monitoring. As glucose levels increase, oxygen levels decrease; consequently, the luminescence intensity and lifetime of the phosphor increase. Although the response of the sensor is dependent on glucose concentration, the ambient oxygen concentration also plays a key role. This could lead to inaccurate glucose readings and increase the risk of hyper- or hypoglycemia. To mitigate this risk, the dependence of hydrogel glucose sensor response on oxygen levels was investigated and compensation methods explored. Sensors were calibrated at different oxygen concentrations using a single generic logistic equation, such that trends in oxygen-dependence were determined as varying parameters in the equation. Each parameter was found to be a function of oxygen concentration, such that the correct glucose calibration equation can be calculated if the oxygen level is known. Accuracy of compensation will be determined by developing an overall calibration, using both glucose and oxygen sensors in parallel, correcting for oxygen fluctuations in real time by intentionally varying oxygen, and calculating the error in actual and predicted glucose levels. While this method was developed for compensation of enzymatic glucose sensors, in principle it can also be implemented with other kinds of sensors utilizing oxidases.

Differential temperature effects on dissipation of excess light energy and energy partitioning in lut2 mutant of Arabidopsis thaliana under photoinhibitory conditions.

PubMed

Popova, Antoaneta V; Dobrev, Konstantin; Velitchkova, Maya; Ivanov, Alexander G

2018-05-03

The high-light-induced alterations in photosynthetic performance of photosystem II (PSII) and photosystem I (PSI) as well as effectiveness of dissipation of excessive absorbed light during illumination for different periods of time at room (22 °C) and low (8-10 °C) temperature of leaves of Arabidopsis thaliana, wt and lut2, were followed with the aim of unraveling the role of lutein in the process of photoinhibition. Photosynthetic parameters of PSII and PSI were determined on whole leaves by PAM fluorometer and oxygen evolving activity-by a Clark-type electrode. In thylakoid membranes, isolated from non-illuminated and illuminated for 4.5 h leaves of wt and lut2 the photochemical activity of PSII and PSI and energy interaction between the main pigment-protein complexes was determined. Results indicate that in non-illuminated leaves of lut2 the maximum rate of oxygen evolution and energy utilization in PSII is lower, excitation pressure of PSII is higher and cyclic electron transport around PSI is faster than in wt leaves. Under high-light illumination, lut2 leaves are more sensitive in respect to PSII performance and the extent of increase of excitation pressure of PSII, Φ NO , and cyclic electron transport around PSI are higher than in wt leaves, especially when illumination is performed at low temperature. Significant part of the excessive light energy is dissipated via mechanism, not dependent on ∆pH and to functioning of xanthophyll cycle in LHCII, operating more intensively in lut2 leaves.

Automatic calibration and control system for a combined oxygen and combustibles analyzer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woolbert, G.D.; Jewett, S.Y.; Robertson, J.W. Jr.

1989-08-01

This patent describes an automatic, periodically calibrating system for continuous output of calibrated signals from a combined oxygen and combustibles analyzer. It comprises: a combined oxygen and combustibles analyzer for sensing a level of oxygen and a level of combustibles in a volatile atmosphere and for producing a first sample signal indicative of the oxygen level and a second sample signal indicative of the combustibles level; means for introducing zero and span calibration test gases into the analyzer; means for periodically calibrating the analyzer. This including: a data control unit; a timer unit; a mechanical unit, means for calculating zeromore » and span values for oxygen and combustibles, means for comparing the calculated zero and span values for oxygen and combustibles to the preset alarm limits for oxygen and combustibles, means for activating an operator alarm, means for calculating oxygen and combustibles drift adjustments, a memory unit; and means for applying the oxygen and combustibles drift adjustments concurrently to the first and second sample signals, according to predetermined mathematical relationship, to obtain calibrated output signals indicative of the oxygen and combustibles level in the volatile atmosphere.« less

Millennial-scale iron fertilization of the eastern equatorial Pacific over the past 100,000 years

NASA Astrophysics Data System (ADS)

Loveley, Matthew R.; Marcantonio, Franco; Wisler, Marilyn M.; Hertzberg, Jennifer E.; Schmidt, Matthew W.; Lyle, Mitchell

2017-10-01

The eastern equatorial Pacific Ocean plays a crucial role in global climate, as it is a substantial source of CO2 to the atmosphere and accounts for a significant portion of global new export productivity. Here we present a 100,000-year sediment core from the eastern equatorial Pacific, and reconstruct dust flux, export productivity and bottom-water oxygenation using excess-230Th-derived fluxes of 232Th and barium, and authigenic uranium concentrations, respectively. We find that during the last glacial period (71,000 to 41,000 years ago), increased delivery of dust to the eastern equatorial Pacific was coeval with North Atlantic Heinrich stadial events. Millennial-scale pulses of increased dust flux coincided with episodes of heightened biological productivity, suggesting that dissolution of dust released iron that promoted ocean fertilization. We also find that periods of low atmospheric CO2 concentrations were associated with suboxic conditions and increased storage of respired carbon in the deep eastern equatorial Pacific. Increases in CO2 concentrations during the deglaciation are coincident with increases in deep Pacific and Southern Ocean water oxygenation levels. We suggest that deep-ocean ventilation was a primary control on CO2 outgassing in this region, with superimposed pulses of high productivity providing a negative feedback.

Hemopexin therapy reverts heme-induced proinflammatory phenotypic switching of macrophages in a mouse model of sickle cell disease.

PubMed

Vinchi, Francesca; Costa da Silva, Milene; Ingoglia, Giada; Petrillo, Sara; Brinkman, Nathan; Zuercher, Adrian; Cerwenka, Adelheid; Tolosano, Emanuela; Muckenthaler, Martina U

2016-01-28

Hemolytic diseases, such as sickle cell anemia and thalassemia, are characterized by enhanced release of hemoglobin and heme into the circulation, heme-iron loading of reticulo-endothelial system macrophages, and chronic inflammation. Here we show that in addition to activating the vascular endothelium, hemoglobin and heme excess alters the macrophage phenotype in sickle cell disease. We demonstrate that exposure of cultured macrophages to hemolytic aged red blood cells, heme, or iron causes their functional phenotypic change toward a proinflammatory state. In addition, hemolysis and macrophage heme/iron accumulation in a mouse model of sickle disease trigger similar proinflammatory phenotypic alterations in hepatic macrophages. On the mechanistic level, this critically depends on reactive oxygen species production and activation of the Toll-like receptor 4 signaling pathway. We further demonstrate that the heme scavenger hemopexin protects reticulo-endothelial macrophages from heme overload in heme-loaded Hx-null mice and reduces production of cytokines and reactive oxygen species. Importantly, in sickle mice, the administration of human exogenous hemopexin attenuates the inflammatory phenotype of macrophages. Taken together, our data suggest that therapeutic administration of hemopexin is beneficial to counteract heme-driven macrophage-mediated inflammation and its pathophysiologic consequences in sickle cell disease. © 2016 by The American Society of Hematology.

The Role of Reactive-Oxygen-Species in Microbial Persistence and Inflammation

PubMed Central

Spooner, Ralee; Yilmaz, Özlem

2011-01-01

The mechanisms of chronic infections caused by opportunistic pathogens are of keen interest to both researchers and health professionals globally. Typically, chronic infectious disease can be characterized by an elevation in immune response, a process that can often lead to further destruction. Reactive-Oxygen-Species (ROS) have been strongly implicated in the aforementioned detrimental response by host that results in self-damage. Unlike excessive ROS production resulting in robust cellular death typically induced by acute infection or inflammation, lower levels of ROS produced by host cells are increasingly recognized to play a critical physiological role for regulating a variety of homeostatic cellular functions including growth, apoptosis, immune response, and microbial colonization. Sources of cellular ROS stimulation can include “danger-signal-molecules” such as extracellular ATP (eATP) released by stressed, infected, or dying cells. Particularly, eATP-P2X7 receptor mediated ROS production has been lately found to be a key modulator for controlling chronic infection and inflammation. There is growing evidence that persistent microbes can alter host cell ROS production and modulate eATP-induced ROS for maintaining long-term carriage. Though these processes have yet to be fully understood, exploring potential positive traits of these “injurious” molecules could illuminate how opportunistic pathogens maintain persistence through physiological regulation of ROS signaling. PMID:21339989

Facile synthesis of ferromagnetic Ni doped CeO2 nanoparticles with enhanced anticancer activity

NASA Astrophysics Data System (ADS)

Abbas, Fazal; Jan, Tariq; Iqbal, Javed; Ahmad, Ishaq; Naqvi, M. Sajjad H.; Malik, Maaza

2015-12-01

NixCe1-xO2 (where x = 0, 0.01, 0.03, 0.05 and 0.07) nanoparticles were synthesized by soft chemical method and were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman, UV-vis absorption spectroscopy and vibrating sample magnetometer (VSM). XRD and Raman results indicated the formation of single phase cubic fluorite structure for the synthesized nanoparticles. Ni dopant induced excessive structural changes such as decrease in crystallite size as well as lattice constants and enhancement in oxygen vacancies in CeO2 crystal structure. These structural variations significantly influenced the optical and magnetic properties of CeO2 nanoparticles. The synthesized NixCe1-xO2 nanoparticles exhibited room temperature ferromagnetic behavior. Ni doping induced effects on the cytotoxicity of CeO2 nanoparticles were examined against HEK-293 healthy cell line and SH-SY5Y neuroblastoma cancer cell line. The prepared NixCe1-xO2 nanoparticles demonstrated differential cytotoxicity. Furthermore, anticancer activity of CeO2 nanoparticles observed to be significantly enhanced with Ni doping which was found to be strongly correlated with the level of reactive oxygen species (ROS) production. The prepared ferromagnetic NixCe1-xO2 nanoparticles with differential cytotoxic nature may be potential for future targeted cancer therapy.

Late paleozoic fusulinoidean gigantism driven by atmospheric hyperoxia.

PubMed

Payne, Jonathan L; Groves, John R; Jost, Adam B; Nguyen, Thienan; Moffitt, Sarah E; Hill, Tessa M; Skotheim, Jan M

2012-09-01

Atmospheric hyperoxia, with pO(2) in excess of 30%, has long been hypothesized to account for late Paleozoic (360-250 million years ago) gigantism in numerous higher taxa. However, this hypothesis has not been evaluated statistically because comprehensive size data have not been compiled previously at sufficient temporal resolution to permit quantitative analysis. In this study, we test the hyperoxia-gigantism hypothesis by examining the fossil record of fusulinoidean foraminifers, a dramatic example of protistan gigantism with some individuals exceeding 10 cm in length and exceeding their relatives by six orders of magnitude in biovolume. We assembled and examined comprehensive regional and global, species-level datasets containing 270 and 1823 species, respectively. A statistical model of size evolution forced by atmospheric pO(2) is conclusively favored over alternative models based on random walks or a constant tendency toward size increase. Moreover, the ratios of volume to surface area in the largest fusulinoideans are consistent in magnitude and trend with a mathematical model based on oxygen transport limitation. We further validate the hyperoxia-gigantism model through an examination of modern foraminiferal species living along a measured gradient in oxygen concentration. These findings provide the first quantitative confirmation of a direct connection between Paleozoic gigantism and atmospheric hyperoxia. © 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.

Spawning activity of the Australian lungfish Neoceratodus forsteri in an impoundment.

PubMed

Roberts, D T; Mallett, S; Krück, N C; Loh, W; Tibbetts, I

2014-01-01

This study assessed the spawning activity of the threatened Australian lungfish Neoceratodus forsteri by measuring egg densities within the artificial habitat of a large impoundment (Lake Wivenhoe, Australia). Eggs were sampled (August to November 2009) from multiple locations across the impoundment, but occurred at highest densities in water shallower than 40 cm along shorelines with a dense cover of submerged terrestrial vegetation. The numbers of eggs declined over the study period and all samples were dominated by early developmental stages and high proportions of unviable eggs. The quality of the littoral spawning habitats declined over the study as flooded terrestrial grasses decomposed and filamentous algae coverage increased. Water temperatures at the spawning site exhibited extreme variations, ranging over 20·4° C in water shallower than 5 cm. Dissolved oxygen concentrations regularly declined to <1 mg l⁻¹ at 40 and 80 cm water depth. Spawning habitats utilised by N. forsteri within impoundments expose embryos to increased risk of desiccation or excessive submergence through water-level variations, and extremes in temperature and dissolved oxygen concentration that present numerous challenges for successful spawning and recruitment of N. forsteri in large impoundment environments. © 2014 The Fisheries Society of the British Isles.

Influence of dietary protein and excess methionine on choline needs for young bobwhite quail

USGS Publications Warehouse

Serafin, J.A.

1982-01-01

Experiments were conducted with young Bobwhite quail (Colinus virginianus) to investigate the effect of differing dietary protein levels and nondetrimental amounts of excess methionine on choline needs. Growth and feed consumption of quail fed an adequate (27.3%) protein purified diet supplemented with 2000 mg/kg of choline were unaffected by increasing the level of excess methionine to 1.75%; however, greater amounts (2.0%, 2.25%) of excess methionine depressed growth (P less than .01), reduced feed consumption (P less than .01), and decreased feed utilization (P less than .05). Quail fed a purified diet containing 13.85% protein and 515 mg/kg of choline grew poorly. Growth was unaffected by additional choline in this diet. Growth was suboptimal among quail fed purified diets containing adequate or high (41.55%) levels of protein in which choline was limiting; however, a high level of protein did not in itself affect performance. Growth was improved by supplemental choline in these diets. Growth of quail fed purified diets with up to 1.35% excess methionine which were limiting (531 mg/kg) in choline was less than that of groups fed 2000 mg/kg of added dietary choline (P less than .01); however, excess methionine did not significantly influence growth of quail fed choline-deficient diets. These experiments indicate that neither high dietary protein nor excess methionine, fed at non-growth-depressing levels, increases dietary choline needs for young Bobwhite quail.

Ubiquitin facilitates a quality-control pathway that removes damaged chloroplasts

DOE PAGES

Woodson, Jesse D.; Joens, Matthew S.; Sinson, Andrew B.; ...

2015-10-23

Energy production by chloroplasts and mitochondria causes constant oxidative damage. A functioning photosynthetic cell requires quality-control mechanisms to turn over and degrade chloroplasts damaged by reactive oxygen species (ROS). Here in this study, we generated a conditionally lethal Arabidopsis mutant that accumulated excess protoporphyrin IX in the chloroplast and produced singlet oxygen. Damaged chloroplasts were subsequently ubiquitinated and selectively degraded. A genetic screen identified the plant U-box 4 (PUB4) E3 ubiquitin ligase as being necessary for this process. pub4-6 mutants had defects in stress adaptation and longevity. As a result, we have identified a signal that leads to the targetedmore » removal of ROS-overproducing chloroplasts.« less

KSC-06pd0564

NASA Image and Video Library

2006-03-29

KENNEDY SPACE CENTER, FLA. - In the Vehicle Assembly Building at NASA's Kennedy Space Center, the nose cap on top of external tank number 119 has been removed. A new gaseous oxygen vent valve will be installed. Tank 119 is designated for mission STS-121. Vapors are created prior to launch as the liquid oxygen in the external tank boils off. At the forward end of each external tank propellant tank is a vent and relief valve that can be opened before launch for venting or by excessive tank pressure for relief. The vent function is available only before launch. Mission STS-121 to the International Space Station is scheduled for launch in July. Photo credit: NASA/Jim Grossmann

KSC-06pd0615

NASA Image and Video Library

2006-04-13

KENNEDY SPACE CENTER, FLA. - In the transfer aisle of the Vehicle Assembly Building, workers work on the rim around the nose cap of external tank number 119, the tank designated for mission STS-121. The cap was removed in order to install a new gaseous oxygen vent valve underneath. Vapors are created prior to launch as the liquid oxygen in the external tank boils off. At the forward end of each external tank propellant tank is a vent and relief valve that can be opened before launch for venting or by excessive tank pressure for relief. The vent function is available only before launch. Mission STS-121 to the International Space Station is scheduled for launch in July. Photo credit: NASA/Jim Grossmann

KSC-06pd0616

NASA Image and Video Library

2006-04-13

KENNEDY SPACE CENTER, FLA. - In the transfer aisle of the Vehicle Assembly Building, workers check the rim around the nose cap of external tank number 119, the tank designated for mission STS-121. The cap was removed in order to install a new gaseous oxygen vent valve underneath. Vapors are created prior to launch as the liquid oxygen in the external tank boils off. At the forward end of each external tank propellant tank is a vent and relief valve that can be opened before launch for venting or by excessive tank pressure for relief. The vent function is available only before launch. Mission STS-121 to the International Space Station is scheduled for launch in July. Photo credit: NASA/Jim Grossmann

Determination of Activities of Niobium in Cu-Nb Melts Containing Dilute Nb

NASA Astrophysics Data System (ADS)

Wang, Daya; Yan, Baijun; Sichen, Du

2015-04-01

The activity coefficients of niobium in Cu-Nb melts were measured by equilibrating solid NbO2 with liquid copper under controlled oxygen potentials in the temperature range of 1773 K to 1898 K (1500 °C to 1625 °C). Either CO-CO2 gas mixture or H2-CO2 gas mixture was employed to obtain the desired oxygen partial pressures. Cu-Nb system was found to follow Henry's law in the composition range studied. The temperature dependence of Henry's constant in the Cu-Nb melts could be expressed as follows: The partial molar excess Gibbs energy change of niobium in Cu-Nb melts can be expressed as follows:

Ubiquitin facilitates a quality-control pathway that removes damaged chloroplasts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woodson, Jesse D.; Joens, Matthew S.; Sinson, Andrew B.

Energy production by chloroplasts and mitochondria causes constant oxidative damage. A functioning photosynthetic cell requires quality-control mechanisms to turn over and degrade chloroplasts damaged by reactive oxygen species (ROS). Here in this study, we generated a conditionally lethal Arabidopsis mutant that accumulated excess protoporphyrin IX in the chloroplast and produced singlet oxygen. Damaged chloroplasts were subsequently ubiquitinated and selectively degraded. A genetic screen identified the plant U-box 4 (PUB4) E3 ubiquitin ligase as being necessary for this process. pub4-6 mutants had defects in stress adaptation and longevity. As a result, we have identified a signal that leads to the targetedmore » removal of ROS-overproducing chloroplasts.« less

Contribution of voltage-dependent K+ channels to metabolic control of coronary blood flow

PubMed Central

Berwick, Zachary C.; Dick, Gregory M.; Moberly, Steven P.; Kohr, Meredith C.; Sturek, Michael; Tune, Johnathan D.

2011-01-01

The purpose of this investigation was to test the hypothesis that KV channels contribute to metabolic control of coronary blood flow and that decreases in KV channel function and/or expression significantly attenuate myocardial oxygen supply-demand balance in the metabolic syndrome (MetS). Experiments were conducted in conscious, chronically instrumented Ossabaw swine fed either a normal maintenance diet or an excess calorie atherogenic diet that produces the clinical phenotype of early MetS. Data were obtained under resting conditions and during graded treadmill exercise before and after inhibition of KV channels with 4-aminopyridine (4-AP, 0.3 mg/kg, i.v.). In lean-control swine, 4-AP reduced coronary blood flow ~15% at rest and ~20% during exercise. Inhibition of KV channels also increased aortic pressure (P < 0.01) while reducing coronary venous Po2 (P < 0.01) at a given level of myocardial oxygen consumption (MVo2). Administration of 4-AP had no effect on coronary blood flow, aortic pressure, or coronary venous Po2 in swine with MetS. The lack of response to 4-AP in MetS swine was associated with a ~20% reduction in coronary KV current (P < 0.01) and decreased expression of KV1.5 channels in coronary arteries (P < 0.01). Together, these data demonstrate that KV channels play an important role in balancing myocardial oxygen delivery with metabolism at rest and during exercise-induced increases in MVo2. Our findings also indicate that decreases in KV channel current and expression contribute to impaired control of coronary blood flow in the MetS. PMID:21771599

40 CFR 63.1218 - What are the standards for hydrochloric acid production furnaces that burn hazardous waste?

Code of Federal Regulations, 2010 CFR

2010-07-01

...)(5) of this section; (2) For mercury, hydrogen chloride and chlorine gas emissions in excess of the... as defined under § 63.2, hydrogen chloride and chlorine gas emissions in excess of the levels... source as defined under § 63.2, hydrogen chloride and chlorine gas emissions in excess of the levels...

40 CFR 63.1218 - What are the standards for hydrochloric acid production furnaces that burn hazardous waste?

Code of Federal Regulations, 2011 CFR

2011-07-01

... paragraph (a)(5) of this section; (2) For mercury, hydrogen chloride and chlorine gas emissions in excess of... source as defined under § 63.2, hydrogen chloride and chlorine gas emissions in excess of the levels... source as defined under § 63.2, hydrogen chloride and chlorine gas emissions in excess of the levels...

Bosch Reactor Development for High Percentage Oxygen Recovery from Carbon Dioxide

NASA Technical Reports Server (NTRS)

Howard, David; Abney, Morgan

2015-01-01

This next Generation Life Support Project entails the development and demonstration of Bosch reaction technologies to improve oxygen recovery from metabolically generated oxygen and/or space environments. A primary focus was placed on alternate carbon formation reactor concepts to improve useful catalyst life for space vehicle applications, and make use of in situ catalyst resources for non-terrestrial surface missions. Current state-of-the-art oxygen recovery systems onboard the International Space Station are able to effectively recover approximately 45 percent of the oxygen consumed by humans and exhausted in the form of carbon dioxide (CO2). Excess CO2 is vented overboard and the oxygen contained in the molecules is lost. For long-duration missions beyond the reaches of Earth for resupply, it will be necessary to recover greater amounts of constituents such as oxygen that are necessary for sustaining life. Bosch technologies theoretically recover 100 percent of the oxygen from CO2, producing pure carbon as the sole waste product. Challenges with this technology revolve around the carbon product fouling catalyst materials, drastically limiting catalyst life. This project successfully demonstrated techniques to extend catalyst surface area exposure times to improve catalyst life for vehicle applications, and demonstrated the use of Martian and lunar regolith as viable catalyst Bosch Reactor Development for High Percentage Oxygen Recovery From Carbon Dioxide materials for surface missions. The Bosch process generates carbon nanotube formation within the regolith, which has been shown to improve mechanical properties of building materials. Production of bricks from post reaction regolith for building and radiation shielding applications were also explored.

Inclusion bodies of aggregated hemosiderins in liver macrophages.

PubMed

Hayashi, Hisao; Tatsumi, Yasuaki; Wakusawa, Shinya; Shigemasa, Ryota; Koide, Ryoji; Tsuchida, Ken-Ichi; Morotomi, Natsuko; Yamashita, Tetsuji; Kumagai, Kotaro; Ono, Yukiya; Hayashi, Kazuhiko; Ishigami, Masatoshi; Goto, Hidemi; Kato, Ayako; Kato, Koichi

2017-12-01

Hemosiderin formation is a structural indication of iron overload. We investigated further adaptations of the liver to excess iron. Five patients with livers showing iron-rich inclusions larger than 2 µm were selected from our database. The clinical features of patients and structures of the inclusions were compared with those of 2 controls with mild iron overload. All patients had severe iron overload with more than 5000 ng/mL of serum ferritin. Etiologies were variable, from hemochromatosis to iatrogenic iron overload. Their histological stages were either portal fibrosis or cirrhosis. Inclusion bodies were ultra-structurally visualized as aggregated hemosiderins in the periportal macrophages. X-ray analysis always identified, in addition to a large amount of iron complexes including oxygen and phosphorus, a small amount of copper and sulfur in the mosaic matrixes of inclusions. There were no inclusions in the control livers. Inclusion bodies, when the liver is loaded with excess iron, may appear in the macrophages as isolated organella of aggregated hemosiderins. Trace amounts of copper-sulfur complexes were always identified in the mosaic matrices of the inclusions, suggesting cuproprotein induction against excess iron. In conclusion, inclusion formation in macrophages may be an adaptation of the liver loaded with excess iron.

Mechanisms of mammalian iron homeostasis

PubMed Central

Pantopoulos, Kostas; Porwal, Suheel Kumar; Tartakoff, Alan; Devireddy, L.

2012-01-01

Iron is vital for almost all organisms because of its ability to donate and accept electrons with relative ease. It serves as a cofactor for many proteins and enzymes necessary for oxygen and energy metabolism, as well as for several other essential processes. Mammalian cells utilize multiple mechanisms to acquire iron. Disruption of iron homeostasis is associated with various human diseases: iron deficiency resulting from defects in acquisition or distribution of the metal causes anemia; whereas iron surfeit resulting from excessive iron absorption or defective utilization causes abnormal tissue iron deposition, leading to oxidative damage. Mammals utilize distinct mechanisms to regulate iron homeostasis at the systemic and cellular levels. These involve the hormone hepcidin and iron regulatory proteins, which collectively ensure iron balance. This review outlines recent advances in iron regulatory pathways, as well as in mechanisms underlying intracellular iron trafficking, an important but less-studied area of mammalian iron homeostasis. PMID:22703180

The Importance of NADPH Oxidases and Redox Signaling in Angiogenesis

PubMed Central

Prieto-Bermejo, Rodrigo; Hernández-Hernández, Angel

2017-01-01

Eukaryotic cells have to cope with the constant generation of reactive oxygen species (ROS). Although the excessive production of ROS might be deleterious for cell biology, there is a plethora of evidence showing that moderate levels of ROS are important for the control of cell signaling and gene expression. The family of the nicotinamide adenine dinucleotide phosphate oxidases (NADPH oxidases or Nox) has evolved to produce ROS in response to different signals; therefore, they fulfil a central role in the control of redox signaling. The role of NADPH oxidases in vascular physiology has been a field of intense study over the last two decades. In this review we will briefly analyze how ROS can regulate signaling and gene expression. We will address the implication of NADPH oxidases and redox signaling in angiogenesis, and finally, the therapeutic possibilities derived from this knowledge will be discussed. PMID:28505091

[Acatalasemia and type 2 diabetes mellitus].

PubMed

Góth, László; Nagy, Teréz; Káplár, Miklós

2015-03-08

The catalase enzyme decomposes the toxic concentrations of hydrogen peroxide into oxygen and water. Hydrogen peroxide is a highly reactive small molecule and its excessive concentration may cause significant damages to proteins, deoxyribonucleic acid, ribonucleic acid and lipids. Acatalasemia refers to inherited deficiency of the catalase enzyme. In this review the authors discuss the possible role of the human catalase enzyme, the metabolism of hydrogen peroxide, and the phenomenon of hydrogen peroxide paradox. In addition, they review data obtained from Hungarian acatalasemic patients indicating an increased frequency of type 2 diabetes mellitus, especially in female patients, and an early onset of type 2 diabetes in these patients. There are 10 catalase gene variants which appear to be responsible for decreased blood catalase activity in acatalasemic patients with type 2 diabetes. It is assumed that low levels of blood catalase may cause an increased concentration of hydrogen peroxide which may contribute to the pathogenesis of type 2 diabetes mellitus.

Trace Mineral Micronutrients and Chronic Periodontitis-a Review.

PubMed

Gaur, Sumit; Agnihotri, Rupali

2017-04-01

Trace mineral micronutrients are imperative for optimum host response. Populations worldwide are prone to their insufficiency owing to lifestyle changes or poor nutritional intake. Balanced levels of trace minerals like iron (Fe), zinc (Zn), selenium (Se) and copper (Cu) are essential to prevent progression of chronic conditions like periodontitis. Their excess as well as deficiency is detrimental to periodontal health. This is specifically true in relation to Fe. Furthermore, some trace elements, e.g. Se, Zn and Cu are integral components of antioxidant enzymes and prevent reactive oxygen species induced destruction of tissues. Their deficiency can worsen periodontitis associated with systemic conditions like diabetes mellitus. With this background, the present review first focusses on the role of four trace minerals, namely, Fe, Zn, Se and Cu in periodontal health followed by an appraisal of the data from case control studies related to their association with chronic periodontitis.

Oil shale retorting and combustion system

DOEpatents

Pitrolo, Augustine A.; Mei, Joseph S.; Shang, Jerry Y.

1983-01-01

The present invention is directed to the extraction of energy values from l shale containing considerable concentrations of calcium carbonate in an efficient manner. The volatiles are separated from the oil shale in a retorting zone of a fluidized bed where the temperature and the concentration of oxygen are maintained at sufficiently low levels so that the volatiles are extracted from the oil shale with minimal combustion of the volatiles and with minimal calcination of the calcium carbonate. These gaseous volatiles and the calcium carbonate flow from the retorting zone into a freeboard combustion zone where the volatiles are burned in the presence of excess air. In this zone the calcination of the calcium carbonate occurs but at the expense of less BTU's than would be required by the calcination reaction in the event both the retorting and combustion steps took place simultaneously. The heat values in the products of combustion are satisfactorily recovered in a suitable heat exchange system.

Storage battery aspects of air-electrode research

NASA Astrophysics Data System (ADS)

Buzelli, E. S.; Berk, L. B.; Demczyk, B. G.; Zuckerbrod, D.

The use of air electrodes in secondary, alkaline energy storage systems offers several significant advantages over other conventional cathode systems. The oxygen, required for operation, is not stored or carried within the battery system. The weight of the air electrode is significantly lower than alternative cathode couples for the same mission. The cost of the air electrode is potentially low. As a result of these characteristics, alkaline electrolyte energy storage systems with air electrodes have the potential for achieving energy density levels in excess of 150 Whr/kg at low costs, $30-$40/kWh. The primary key to a successful metal-air secondary battery for an EV application is the development of a bifunctinal air electrode. This paper discusses the various aspects of air electrode research for this application, as well as the physical and performance requirements of the air electrode in this advanced technology battery system.

Storage battery aspects of air-electrode research

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buzzelli, E.S.; Berk, L.B.; Demczyk, B.G.

1983-08-01

The use of air electrodes in secondary, alkaline energy storage systems offers several significant advantages over other conventional cathode systems. The oxygen, required for operation, is not stored or carried within the battery system. The weight of the air electrode is significantly lower than alternative cathode couples for the same mission. The cost of the air electrode is potentially low. As a result of these characteristics, alkaline electrolyte energy storage systems with air electrodes have the potential for achieving energy density levels in excess of 150 Whr/kg at low costs, $30-$40/kWh. The primary key to a successful metal-air secondary batterymore » for an EV application is the development of a bifunctional air electrode. This paper discusses the various aspects of air electrode research for this application, as well as the physical and performance requirements of the air electrode in this advanced technology battery system.« less

The Role of Organelle Stresses in Diabetes Mellitus and Obesity: Implication for Treatment

PubMed Central

Chang, Yi-Cheng; Hee, Siow-Wey; Hsieh, Meng-Lun; Chuang, Lee-Ming

2015-01-01

The type 2 diabetes pandemic in recent decades is a huge global health threat. This pandemic is primarily attributed to the surplus of nutrients and the increased prevalence of obesity worldwide. In contrast, calorie restriction and weight reduction can drastically prevent type 2 diabetes, indicating a central role of nutrient excess in the development of diabetes. Recently, the molecular links between excessive nutrients, organelle stress, and development of metabolic disease have been extensively studied. Specifically, excessive nutrients trigger endoplasmic reticulum stress and increase the production of mitochondrial reactive oxygen species, leading to activation of stress signaling pathway, inflammatory response, lipogenesis, and pancreatic beta-cell death. Autophagy is required for clearance of hepatic lipid clearance, alleviation of pancreatic beta-cell stress, and white adipocyte differentiation. ROS scavengers, chemical chaperones, and autophagy activators have demonstrated promising effects for the treatment of insulin resistance and diabetes in preclinical models. Further results from clinical trials are eagerly awaited. PMID:26613076

Impact of the excess sludge modification with selected chemical reagents on the increase of dissolved organic substances concentration compounds transformations in activated sludge.

PubMed

Zawieja, Iwona; Lidia, Wolny; Marta, Próba

2017-07-01

Submission of excess sludge initial disintegration process significantly affects the efficiency of anaerobic stabilization process. Expression of increasing the concentration of organic matter in dissolved form is to increase sludge disintegration. As a result of chemical modification is an increase of the chemical oxygen demand and the concentration of volatile fatty acids. The aim of this study was to determine the impact of the disintegration process with selected chemical reagents to increase the concentration of organic substances in dissolved form. The process of chemical disintegration of excess sludge was treated using the following reagents: Mg(OH) 2 , Ca(OH) 2 , HCl, H 2 SO 4 , H 2 O 2 . The modification was carried out at ambient temperature for 2, 6 and 24h. During sludge disintegration it was noticed the growth of indicators values that confirmed the susceptibility of prepared sludge to biodegradation. Copyright © 2017 Elsevier Inc. All rights reserved.

Transesterification of Waste Activated Sludge for Biosolids Reduction and Biodiesel Production.

PubMed

Maeng, Min Ho; Cha, Daniel K

2018-02-01

  Transesterification of waste activated sludge (WAS) was evaluated as a cost-effective technique to reduce excess biosolids and recover biodiesel feedstock from activated sludge treatment processes. A laboratory-scale sequencing batch reactor (SBR) was operated with recycling transesterification-treated WAS back to the aeration basin. Seventy percent recycling of WAS resulted in a 48% reduction of excess biosolids in comparison with a conventional SBR, which was operated in parallel as the control SBR. Biodiesel recovery of 8.0% (dried weight basis) was achieved at an optimum transesterification condition using acidic methanol and xylene as cosolvent. Average effluent soluble chemical oxygen demand (COD) and total suspended solids (TSS) concentrations from the test SBR and control SBR were comparable, indicating that the recycling of transesterification-treated WAS did not have detrimental effect on the effluent quality. This study demonstrated that transesterification and recycling of WAS may be a feasible technique for reducing excess biosolids, while producing valuable biodiesel feedstock from the activated sludge process.

Astragaloside-IV Alleviates Heat-Induced Inflammation by Inhibiting Endoplasmic Reticulum Stress and Autophagy.

PubMed

Dong, Zhiwei; Zhou, Jian; Zhang, Ying; Chen, Yajie; Yang, Zichen; Huang, Guangtao; Chen, Yu; Yuan, Zhiqiang; Peng, Yizhi; Cao, Tongtong

2017-01-01

Thermal injury is the main cause of pulmonary disease in stroke after burn and can be life threatening. Heat-induced inflammation is an important factor that triggers a series of induces pathological changes. However, this mechanism underlying heat-induced inflammation in thermal inhalation injury remains unclear. Studies have revealed that astragaloside-IV (AS-IV), a natural compound extracted from Astragalus membranaceus, has protective effects in inflammatory diseases. Here, we investigated whether the protective effects of AS-IV occur because of the suppression of heat-induced endoplasmic reticulum (ER) stress and excessive autophagy Methods: AS-IV was administered to Wistar rats after thermal inhalation injury and 16HBE140-cells were treated with AS-IV. TNF-α, IL-6, and IL-8 levels were determined by ELISA and real-time PCR. ER stress and autophagy were determined by western blot. Autophagic flux was measured by recording the fluorescence emission of the fusion protein mRFP-GFP-LC3 by dynamic live-cell imaging. AS-IV had protective effects against heat-induced reactive oxygen species production and attenuated ER stress. AS IV alleviated heat-induced excessive autophagy in vitro and in vivo. Excessive autophagy was attenuated by the PERK inhibitor GSK2656157 and eIF2α siRNA, suggesting that heat stress-induced autophagy can activate the PERK-eIF2α pathway. Beclin 1 and Atg5 siRNAs inhibited the upregulation of the inflammatory cytokines TNF-α, IL-6, and IL-8 after heat exposure. Thus, AS-IV may attenuate inflammatory responses by disrupting the crosstalk between autophagy and the PERK-eIF2α pathway and may be an ideal agent for treating inflammatory pulmonary diseases. © 2017 The Author(s). Published by S. Karger AG, Basel.

The effects of interval- vs. continuous exercise on excess post-exercise oxygen consumption and substrate oxidation rates in subjects with type 2 diabetes.

PubMed

Karstoft, Kristian; Wallis, Gareth A; Pedersen, Bente K; Solomon, Thomas P J

2016-09-01

For unknown reasons, interval training often reduces body weight more than energy-expenditure matched continuous training. We compared the acute effects of time-duration and oxygen-consumption matched interval- vs. continuous exercise on excess post-exercise oxygen consumption (EPOC), substrate oxidation rates and lipid metabolism in the hours following exercise in subjects with type 2 diabetes (T2D). Following an overnight fast, ten T2D subjects (M/F: 7/3; age=60.3±2.3years; body mass index (BMI)=28.3±1.1kg/m(2)) completed three 60-min interventions in a counterbalanced, randomized order: 1) control (CON), 2) continuous walking (CW), 3) interval-walking (IW - repeated cycles of 3min of fast and 3min of slow walking). Indirect calorimetry was applied during each intervention and repeatedly for 30min per hour during the following 5h. A liquid mixed meal tolerance test (MMTT, 450kcal) was consumed by the subjects 45min after completion of the intervention with blood samples taken regularly. Exercise interventions were successfully matched for total oxygen consumption (CW=1641±133mL/min; IW=1634±126mL/min, P>0.05). EPOC was higher after IW (8.4±1.3l) compared to CW (3.7±1.4l, P<0.05). Lipid oxidation rates were increased during the MMTT in IW (1.03±0.12mg/kg per min) and CW (0.87±0.04mg/kg per min) compared with CON (0.73±0.04mg/kg per min, P<0.01 and P<0.05, respectively), with no difference between IW and CW. Moreover, free fatty acids and glycerol concentrations, and glycerol kinetics were increased comparably during and after IW and CW compared to CON. Interval exercise results in greater EPOC than oxygen-consumption matched continuous exercise during a post-exercise MMTT in subjects with T2D, whereas effects on substrate oxidation and lipid metabolism are comparable. Copyright © 2016 Elsevier Inc. All rights reserved.

The cytochrome bd oxidase of Escherichia coli prevents respiratory inhibition by endogenous and exogenous hydrogen sulfide

PubMed Central

Korshunov, Sergey; Imlay, Karin R. C.; Imlay, James A.

2016-01-01

Summary When sulfur compounds are scarce or difficult to process, E. coli adapts by inducing the high-level expression of sulfur-compound importers. If cystine then becomes available, the cystine is rapidly overimported and reduced, leading to a burgeoning pool of intracellular cysteine. Most of the excess cysteine is exported, but some is adventitiously degraded, with the consequent release of sulfide. Sulfide is a potent ligand of copper and heme moieties, raising the prospect that it interferes with enzymes. We observed that when cystine was provided and sulfide levels rose, E. coli became strictly dependent upon cytochrome bd oxidase for continued respiration. Inspection revealed that low-micromolar levels of sulfide inhibited the proton-pumping cytochrome bo oxidase that is regarded as the primary respiratory oxidase. In the absence of the back-up cytochrome bd oxidase, growth failed. Exogenous sulfide elicited the same effect. The potency of sulfide was enhanced when oxygen concentrations were low. Natural oxic-anoxic interfaces are often sulfidic, including the intestinal environment where E. coli dwells. We propose that the sulfide resistance of the cytochrome bd oxidase is a key trait that permits respiration in such habitats. PMID:26991114

Modelingofwaterisotopesinpolarregionsandapplicationtoicecorestudies

NASA Astrophysics Data System (ADS)

Jouzel, J.

2012-04-01

Willi Dansgaard spear-headed the use of the stable isotopes of water in climatology and palaeoclimatology especially as applied to deep ice cores for which measurements of the oxygen and hydrogen isotope ratios remain the key tools for reconstructing continuous palaeotemperature records. In the line of his pioneering work on "Stable isotopes in precipitation" published in Tellus in 1964, I will review how isotopic models, either Rayleigh type or based on the implementation of water isotopes in General Circulation Models, have developed and been used for applications in polar ice core studies. This will include a discussion of the conventional approach for interpreting water isotopes in ice cores and of additional information provided by measurements of the deuterium excess and more recently of the 17O-excess.

[Relationship among the Oxygen Concentration, Reactive Oxygen Species and the Biological Characteristics of Mouse Bone Marrow Hematopoietic Stem Cells].

PubMed

Ren, Si-Hua; He, Yu-Xin; Ma, Yi-Ran; Jin, Jing-Chun; Kang, Dan

2016-02-01

To investigate the effects of oxygen concentration and reactive oxygen species (ROS) on the biological characteristics of hematopoietic stem cells (HSC) and to analyzed the relationship among the oxygen concentration, ROS and the biological characteristics of mouse HSC through simulation of oxygen environment experienced by PB HSC during transplantation. The detection of reactive oxygen species (ROS), in vitro amplification, directional differentiation (BFU-E, CFU-GM, CFU-Mix), homing of adhesion molecules (CXCR4, CD44, VLA4, VLA5, P-selectin), migration rate, CFU-S of NOD/SCID mice irradiated with sublethal dose were performed to study the effect of oxgen concentration and reactive oxygen species on the biological characteristics of mouse BM-HSC and the relationship among them. The oxygen concentrations lower than normal oxygen concentration (especially hypoxic oxygen environment) could reduce ROS level and amplify more Lin(-) c-kit(+) Sca-1(+) BM HSC, which was more helpful to the growth of various colonies (BFU-E, CFU-GM, CFU-Mix) and to maintain the migratory ability of HSC, thus promoting CFU-S growth significantly after the transplantation of HSC in NOD/SCID mice irradiated by a sublethal dose. BM HSC exposed to oxygen environments of normal, inconstant oxygen level and strenuously thanging of oxygen concentration could result in higher level of ROS, at the same time, the above-mentioned features and functional indicators were relatively lower. The ROS levels of BM HSC in PB HSCT are closely related to the concentrations and stability of oxygen surrounding the cells. High oxygen concentration results in an high level of ROS, which is not helpful to maintain the biological characteristics of BM HSC. Before transplantation and in vitro amplification, the application of antioxidancs and constant oxygen level environments may be beneficial for transplantation of BMMSC.

Effect of Structural Relaxation on the In-Plane Electrical Resistance of Oxygen-Underdoped ReBaCuO (Re = Y, Ho) Single Crystals

NASA Astrophysics Data System (ADS)

Vovk, Ruslan V.; Vovk, Nikolaj R.; Dobrovolskiy, Oleksandr V.

2014-05-01

The effect of jumpwise temperature variation and room-temperature storing on the basal-plane electrical resistivity of underdoped ReBaCuO (Re = Y, Ho) single crystals is investigated. Reducing the oxygen content has been revealed to lead to the phase segregation accompanied by both, labile component diffusion and structural relaxation in the sample volume. Room-temperature storing of single crystals with different oxygen hypostoichiometries leads to a substantial widening of the rectilinear segment in in conjunction with a narrowing of the temperature range of existence of the pseudogap state. It is established that the excess conductivity obeys an exponential law in a broad temperature range, while the pseudogap's temperature dependence is described satisfactory in the framework of the BCS-BEC crossover theory. Substituting yttrium with holmium essentially effects the charge distribution and the effective interaction in CuO planes, thereby stimulating disordering processes in the oxygen subsystem. This is accompanied by a notable shift of the temperature zones corresponding to transitions of the metal-insulator type and to the regime of manifestation of the pseudogap anomaly.

Oxygen vacancy ordering in transition-metal-oxide LaCoO3 films

NASA Astrophysics Data System (ADS)

Biskup, Neven; Salafranca, Juan; Mehta, Virat; Suzuki, Yuri; Pennycook, Stephen; Pantelides, Sokrates; Varela, Maria

2013-03-01

Oxygen vacancies in complex oxides affect the structure and the electronic and magnetic properties. Here we use atomically-resolved Z-contrast imaging, electron-energy-loss spectroscopy and densityfunctional calculations to demonstrate that ordered oxygen vacancies may act as the controlling degree of freedom for the structural, electronic, and magnetic properties of LaCoO3 thin films. We find that epitaxial strain is released through the formation of O vacancy superlattices. The O vacancies donate excess electrons to the Co d-states, resulting in ferromagnetic ordering. The appearance of Peierls-like minigaps followed by strain relaxation triggers a nonlinear rupture of the energy bands, which explains the observed insulating behavior. We conclude that oxygen vacancy ordering constitutes a degree of freedom that can be used to engineer novel behavior in complex-oxide films. Research at ORNL supported by U.S. DOE-BES, Materials Sciences and Engineering Div. and by ORNL's ShaRE User Program (DOE-BES), at UCM by the ERC Starting Inv. Award, at UC Berkeley and LBNL by BES-DMSE, at Vanderbilt by U.S DOE and the McMinn Endowment.

Influence of shielding gas on the mechanical and metallurgical properties of DP-GMA-welded 5083-H321 aluminum alloy

NASA Astrophysics Data System (ADS)

Koushki, Amin Reza; Goodarzi, Massoud; Paidar, Moslem

2016-12-01

In the present research, 6-mm-thick 5083-H321 aluminum alloy was joined by the double-pulsed gas metal arc welding (DP-GMAW) process. The objective was to investigate the influence of the shielding gas composition on the microstructure and properties of GMA welds. A macrostructural study indicated that the addition of nitrogen and oxygen to the argon shielding gas resulted in better weld penetration. Furthermore, the tensile strength and bending strength of the welds were improved when oxygen and nitrogen (at concentrations as high as approximately 0.1vol%) were added to the shielding gas; however, these properties were adversely affected when the oxygen and nitrogen contents were increased further. This behavior was attributed to the formation of excessive brown and black oxide films on the bead surface, the formation of intermetallic compounds in the weld metal, and the formation of thicker oxide layers on the bead surface with increasing nitrogen and oxygen contents in the argon-based shielding gas. Analysis by energy-dispersive X-ray spectroscopy revealed that most of these compounds are nitrides or oxides.

Nanoscale Investigation of Grain Growth in RF-Sputtered Indium Tin Oxide Thin Films by Scanning Probe Microscopy

NASA Astrophysics Data System (ADS)

Lamsal, B. S.; Dubey, M.; Swaminathan, V.; Huh, Y.; Galipeau, D.; Qiao, Q.; Fan, Q. H.

2014-11-01

This work studied the electronic characteristics of the grains and grain boundaries of indium tin oxide (ITO) thin films using electrostatic and Kelvin probe force microscopy. Two types of ITO films were compared, deposited using radiofrequency magnetron sputtering in pure argon or 99% argon + 1% oxygen, respectively. The average grain size and surface roughness increased with substrate temperature for the films deposited in pure argon. With the addition of 1% oxygen, the increase in the grain size was inhibited above 150°C, which was suggested to be due to passivation of the grains by the excess oxygen. Electrostatic force microscopy and Kelvin probe force microscopy (KPFM) images confirmed that the grain growth was defect mediated and occurred at defective interfaces at high temperatures. Films deposited at room temperature with 1% oxygen showed crystalline nature, while films deposited with pure argon at room temperature were amorphous as observed from KPFM images. The potential drop across the grain and grain boundary was determined by taking surface potential line profiles to evaluate the electronic properties.

The combined effects of carbon/nitrogen ratio, suspended biomass, hydraulic retention time and dissolved oxygen on nutrient removal in a laboratory-scale anaerobic-anoxic-oxic activated sludge biofilm reactor.

PubMed

Manu, D S; Kumar Thalla, Arun

2018-01-01

The current trend in sustainable development deals mainly with environmental management. There is a need for economically affordable, advanced treatment methods for the proper treatment and management of domestic wastewater containing excess nutrients (such as nitrogen and phosphorus) which can cause eutrophication. The reduction of the excess nutrient content of wastewater by appropriate technology is of much concern to the environmentalist. In the current study, a novel integrated anaerobic-anoxic-oxic activated sludge biofilm (A 2 O-AS-biofilm) reactor was designed and operated to improve the biological nutrient removal by varying reactor operating conditions such as carbon to nitrogen (C/N) ratio, suspended biomass, hydraulic retention time (HRT) and dissolved oxygen (DO). Based on various trials, it was seen that the A 2 O-AS-biofilm reactor achieved good removal efficiencies with regard to chemical oxygen demand (95.5%), total phosphorus (93.1%), ammonia nitrogen concentration (NH 4 + -N) (98%) and total nitrogen (80%) when the reactor was maintained at C/N ratio of 4, suspended biomass of 3 to 3.5 g/L, HRT of 10 h, and DO of 1.5 to 2.5 mg/L. Scanning electron microscopy (SEM) of suspended and attached biofilm showed a dense structure of coccus and bacillus bacteria with the diameter ranging from 0.3 to 1.2 μm. The Fourier transform infrared (FTIR) spectroscopy results indicated phosphorylated macromolecules and carbohydrates mix or bind with extracellular proteins in exopolysaccharides.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Popp, R.A.; Marsh, C.L.; Skow, L.C.

Hemoglobins of mouse embryos at 11.5 through 16.5 days of gestation were separated by electrophoresis on cellulose acetate and quantitated by a scanning densitometer to study the effects of two radiation-induced mutations on the expression of embryonic hemoglobin genes in mice. Normal mice produce three kinds of embryonic hemoglobins. In heterozygous ..cap alpha..-thalassemic embryos, expression of EI (x/sub 2/y/sub 2/) and EII (..cap alpha../sub 2/y/sub 2/) is deficient because the x- and ..cap alpha..-globin genes of one of the allelic pairs of Hba on chromosome 11 was deleted or otherwise inactivated by X irradiation. Simultaneous inactivation of the x- andmore » ..cap alpha..-globin genes indicates that these genes must be closely linked. Reduced x- and ..cap alpha..-chain synthesis results in an excess of y chains that associate as homotetramers. This unique y/sub 4/ hemoglobin also appears in ..beta..-duplication embryos where excess y chains are produced by the presence of three rather than two functional alleles of y- and ..beta..-globin genes. In double heterozygotes, which have a single functional allele of x- and ..cap alpha..-globin genes and three functional alleles of y- and ..beta..-globin genes, synthesis of ..cap alpha.. and non-..cap alpha.. chains is severely imbalanced and half of the total hemoglobin is y/sub 4/. Mouse y/sub 4/ has a high affinity for oxygen, P/sub 50/ of less than 10 mm Hg, but it lacks cooperativity so is inefficient for oxygen transport. The death of double heterozygotes in late fetal or neonatal life may be in large part to oxygen deprivation to the tissues.« less

Effects of natural and human-induced hypoxia on coastal benthos

NASA Astrophysics Data System (ADS)

Levin, L. A.; Ekau, W.; Gooday, A. J.; Jorissen, F.; Middelburg, J. J.; Naqvi, W.; Neira, C.; Rabalais, N. N.; Zhang, J.

2009-04-01

Coastal hypoxia (<1.42 ml L-1; 62.5 μM; 2 mg L-1, approx. 30% oxygen saturation) occurs seasonally in many estuaries, fjords, and along open coasts subject to upwelling or excessive riverine nutrient input, and permanently in some isolated seas and marine basins. Underlying causes of hypoxia include enhanced nutrient input from natural causes (upwelling) or anthropogenic origin (eutrophication) and reduction of mixing by limited circulation or enhanced stratification; combined these lead to higher surface water production, microbial respiration and eventual oxygen depletion. Advective inputs of low-oxygen waters may initiate or expand hypoxic conditions. Responses of estuarine, enclosed sea, and open shelf benthos to hypoxia depend on the duration, predictability, and intensity of oxygen depletion and on whether H2S is formed. Under suboxic conditions, large mats of filamentous sulfide oxidizing bacteria cover the seabed and consume sulfide, thereby providing a detoxified microhabitat for eukaryotic benthic communities. Calcareous foraminiferans and nematodes are particularly tolerant of low oxygen concentrations and may attain high densities and dominance, often in association with microbial mats. When oxygen is sufficient to support metazoans, small, soft-bodied invertebrates (typically annelids), often with short generation times and elaborate branchial structures, predominate. Large taxa are more sensitive than small taxa to hypoxia. Crustaceans and echinoderms are typically more sensitive to hypoxia, with lower oxygen thresholds, than annelids, sipunculans, molluscs and cnidarians. Mobile fish and shellfish will migrate away from low-oxygen areas. Within a species, early life stages may be more subject to oxygen stress than older life stages. Hypoxia alters both the structure and function of benthic communities, but effects may differ with regional hypoxia history. Human-caused hypoxia is generally linked to eutrophication, and occurs adjacent to watersheds with large populations or agricultural activities. Many occurrences are seasonal, within estuaries, fjords or enclosed seas of the North Atlantic and the NW Pacific Oceans. Benthic faunal responses, elicited at oxygen levels below 2 ml L-1, typically involve avoidance or mortality of large species and elevated abundances of enrichment opportunists, sometimes prior to population crashes. Areas of low oxygen persist seasonally or continuously beneath upwelling regions, associated with the upper parts of oxygen minimum zones (SE Pacific, W Africa, N Indian Ocean). These have a distribution largely distinct from eutrophic areas and support a resident fauna that is adapted to survive and reproduce at oxygen concentrations <0.5 ml L-1. Under both natural and eutrophication-caused hypoxia there is loss of diversity, through attrition of intolerant species and elevated dominance, as well as reductions in body size. These shifts in species composition and diversity yield altered trophic structure, energy flow pathways, and corresponding ecosystem services such as production, organic matter cycling and organic C burial. Increasingly the influences of nature and humans interact to generate or exacerbate hypoxia. A warmer ocean is more stratified, holds less oxygen, and may experience greater advection of oxygen-poor source waters, making new regions subject to hypoxia. Future understanding of benthic responses to hypoxia must be established in the context of global climate change and other human influences such as overfishing, pollution, disease, habitat loss, and species invasions.

EPOC Comparison between Isocaloric Bouts of Steady-State Aerobic, Intermittent Aerobic, and Resistance Training

ERIC Educational Resources Information Center

Greer, Beau Kjerulf; Sirithienthad, Prawee; Moffatt, Robert J.; Marcello, Richard T.; Panton, Lynn B.

2015-01-01

Purpose: Excess postexercise oxygen consumption (EPOC) is dependent on intensity, duration, and mode of exercise. The purpose of this study was to compare the effect of both exercise mode and intensity on EPOC while controlling for caloric expenditure and duration. Method: Ten low to moderately physically active men (22 ± 2 yrs) performed 3…

Curing preceramic polymers by exposure to nitrogen dioxide

NASA Technical Reports Server (NTRS)

Rabe, James A. (Inventor); Lipowitz, Jonathan (Inventor); Lu, Paul P. (Inventor)

1991-01-01

A rapid method of infusibilizing (curing) preceramic polymers comprising treatment said polymers with gaseous nitrogen dioxide. The infusibilized polymers may be pyrolyzed to temperatures in excess of about 800.degree. C. to yield ceramic materials with low oxygen content and, thus, good thermal stability. The methods are especially useful for the production of ceramic fibers and, more specifically, to the on-line production of ceramic fibers.

[Pregnancy toxemia. Oxygen input/extraction in preeclampsia-eclampsia].

PubMed

Rodríguez-Badillo, R F; Noriega-R, T; Audifred-Salomón, J R; García-Lara, E

1996-07-01

We tried to determine if the toxemia of pregnancy has during its clinical evolution a dependent DO2/VO2 relationship and determine its critical DO2 and finally define if this has a prognostic value. There were included patients with diagnosis of preeclampsia/eclampsia that were enter at the Intensive Care Unit for treatment and monitoring. It was placed a catheter in the pulmonary artery and it was determine the cardiac output and by means of standard formulas the DO2, VO2 and EO2 were calculated. The critical delivery of oxygen was stablished in agree at the Gutiérrez's method. At the same time it was monitorised the base excess which was gotten from arterial and venous blood gases. 36 patients (29 with preclampsia and 7 with eclampsia) were included, with a mean age of 26.3 years old. The mean gestational age was 36.1 weeks. The critical delivery for preeclamptic patients was stablished in 924 mL/min and at the eclamptic patients in 830 mL/min: both values had prognostic correlation with survival and nonsurvival patients (p < 0.001, x2 = 28.29). In survival patients it was a dependent DO2/VO2 relationship during the first 72 hours of study and then it was independent; this fact was accompaniment of a positive increase in the base excess and a decreasing in the EO2 values (< 27%). In the nonsurvival group, these mainteined a DO2/VO2 relationship in a dependent way during all the study and it was accompaniment with a continuous negative base excess with values of EO2 > 30%. The toxemia of pregnancy had a behaviour like state accompaniment of a dependent DO2/VO2 relationship causing an important oxygen deficient that was improved was improved in the survival patients that reach values over the critical delivery. These facts suggesting the presence of a metabolic blockade in variable degree that can improve or increase agree a therapeutic manipulations in the critic DO2.

Comparison of the Atomic Oxygen Erosion Depth and Cone Height of Various Materials at Hyperthermal Energy

NASA Technical Reports Server (NTRS)

Waters, Deborah L.; Banks, Bruce A.; Thorson, Stephen D.; deGroh, Kim, K.; Miller, Sharon K.

2007-01-01

Atomic oxygen readily reacts with most spacecraft polymer materials exposed to the low Earth orbital (LEO) environment. If the atomic oxygen arrival comes from a fixed angle of impact, the resulting erosion will foster the development of a change in surface morphology as material thickness decreases. Hydrocarbon and halopolymer materials, as well as graphite, are easily oxidized and textured by directed atomic oxygen in LEO at energies of approx.4.5 eV. What has been curious is that the ratio of cone height to erosion depth is quite different for different materials. The formation of cones under fixed direction atomic oxygen attack may contribute to a reduction in material tensile strength in excess of that which would occur if the cone height to erosion depth ratio was very low because of greater opportunities for crack initiation. In an effort to understand how material composition affects the ratio of cone height to erosion depth, an experimental investigation was conducted on 18 different materials exposed to a hyperthermal energy directed atomic oxygen source (approx.70 eV). The materials were first salt-sprayed to provide microscopic local areas that would be protected from atomic oxygen. This allowed erosion depth measurements to be made by scanning microscopy inspection. The polymers were then exposed to atomic oxygen produced by an end Hall ion source that was operated on pure oxygen. Samples were exposed to an atomic oxygen effective fluence of 1.0x10(exp 20) atoms/sq cm based on Kapton H polyimide erosion. The average erosion depth and average cone height were determined using field emission scanning electron microscopy (FESEM). The experimental ratio of average cone height to erosion depth is compared to polymer composition and other properties.

A Small Molecule Polyamine Oxidase Inhibitor Blocks Androgen-Induced Oxidative Stress and Delays Prostate Cancer Progression in the TRAMP Mouse Model

PubMed Central

Basu, Hirak S.; Thompson, Todd A.; Church, Dawn R.; Clower, Cynthia C.; Mehraein-Ghomi, Farideh; Amlong, Corey A.; Martin, Christopher T.; Woster, Patrick M.; Lindstrom, Mary J.; Wilding, George

2009-01-01

High levels of reactive oxygen species (ROS) present in human prostate epithelia are an important etiological factor in prostate cancer (CaP) occurrence, recurrence and progression. Androgen induces ROS production in the prostate by a yet unknown mechanism. Here, to the best of our knowledge, we report for the first time that androgen induces an overexpression of spermidine/spermine N1-acetyltransferase (SSAT), the rate-limiting enzyme in the polyamine oxidation pathway. As prostatic epithelia produce a large excess of polyamines, the androgen-induced polyamine oxidation that produces H2O2 could be a major reason for the high ROS levels in the prostate epithelia. A small molecule polyamine oxidase inhibitor N,N'-butanedienyl butanediamine (MDL 72,527 or CPC-200) effectively blocks androgen-induced ROS production in human CaP cells as well as significantly delays CaP progression and death in animals developing spontaneous CaP. These data demonstrate that polyamine oxidation is not only a major pathway for ROS production in prostate, but inhibiting this pathway also successfully delays prostate cancer progression. PMID:19773450

The salinity, temperature, and delta18O of the glacial deep ocean.

PubMed

Adkins, Jess F; McIntyre, Katherine; Schrag, Daniel P

2002-11-29

We use pore fluid measurements of the chloride concentration and the oxygen isotopic composition from Ocean Drilling Program cores to reconstruct salinity and temperature of the deep ocean during the Last Glacial Maximum (LGM). Our data show that the temperatures of the deep Pacific, Southern, and Atlantic oceans during the LGM were relatively homogeneous and within error of the freezing point of seawater at the ocean's surface. Our chloride data show that the glacial stratification was dominated by salinity variations, in contrast with the modern ocean, for which temperature plays a primary role. During the LGM the Southern Ocean contained the saltiest water in the deep ocean. This reversal of the modern salinity contrast between the North and South Atlantic implies that the freshwater budget at the poles must have been quite different. A strict conversion of mean salinity at the LGM to equivalent sea-level change yields a value in excess of 140 meters. However, the storage of fresh water in ice shelves and/or groundwater reserves implies that glacial salinity is a poor predictor of mean sea level.

Impact of aerobic stabilization on the characteristics of treatment sludge in the leather tanning industry.

PubMed

Cokgor, Emine Ubay; Aydinli, Ebru; Tas, Didem Okutman; Zengin, Gulsum Emel; Orhon, Derin

2014-01-01

The efficiency of aerobic stabilization on the treatment sludge generated from the leather industry was investigated to meet the expected characteristics and conditions of sludge prior to landfill. The sludge types subjected to aerobic stabilization were chemical treatment sludge, biological excess sludge, and the mixture of both chemical and biological sludges. At the end of 23 days of stabilization, suspended solids, volatile suspended solids and total organic carbon removal efficiencies were determined as 17%, 19% and 23% for biological sludge 31%, 35% and 54% for chemical sludge, and 32%, 34% and 63% for the mixture of both chemical and biological sludges, respectively. Model simulations of the respirometric oxygen uptake rate measurements showed that the ratio of active biomass remained the same at the end of the stabilization for all the sludge samples. Although mixing the chemical and biological sludges resulted in a relatively effective organic carbon and solids removal, the level of stabilization achieved remained clearly below the required level of organic carbon content for landfill. These findings indicate the potential risk of setting numerical restrictions without referring to proper scientific support.