Oxygen consumption rate of cells in 3D culture: the use of experiment and simulation to measure kinetic parameters and optimise culture conditions.

PubMed

Streeter, Ian; Cheema, Umber

2011-10-07

Understanding the basal O(2) and nutrient requirements of cells is paramount when culturing cells in 3D tissue models. Any scaffold design will need to take such parameters into consideration, especially as the addition of cells introduces gradients of consumption of such molecules from the surface to the core of scaffolds. We have cultured two cell types in 3D native collagen type I scaffolds, and measured the O(2) tension at specific locations within the scaffold. By changing the density of cells, we have established O(2) consumption gradients within these scaffolds and using mathematical modeling have derived rates of consumption for O(2). For human dermal fibroblasts the average rate constant was 1.19 × 10(-17) mol cell(-1) s(-1), and for human bone marrow derived stromal cells the average rate constant was 7.91 × 10(-18) mol cell(-1) s(-1). These values are lower than previously published rates for similar cells cultured in 2D, but the values established in this current study are more representative of rates of consumption measured in vivo. These values will dictate 3D culture parameters, including maximum cell-seeding density and maximum size of the constructs, for long-term viability of tissue models.

Measurements of the O+ plus N2 and O+ plus O2 reaction rates from 300 to 900 K

NASA Technical Reports Server (NTRS)

Chen, A.; Johnsen, R.; Biondi, M. A.

1977-01-01

Rate coefficients for the O(+) + N2 atom transfer and O(+) + O2 charge transfer reactions are determined at thermal energies between 300 K and 900 K difference in a heated drift tube mass spectrometer apparatus. At 300 K the values K(O(+) + N2) = (1.2 plus or minus 0.1) x 10 to the negative 12 power cubic cm/sec and k(O(+) + O2) = (2.1 plus or minus 0.2) x 10 to the negative 11 power cubic cm/sec were obtained, with a 50% difference decrease in the reaction rates upon heating to 700 K. These results are in good agreement with heated flowing afterglow results, but the O(+) + O2 thermal rate coefficients are systematically lower than equivalent Maxwellian rates inferred by conversion of nonthermal drift tube and flow drift data.

Isotopomer fractionation during N2O consumption within soil mesocosms as a function of water filled pore space

NASA Astrophysics Data System (ADS)

Jinuntuya, M.; Ostrom, N. E.; Ostrom, P.; Sutka, R.

2005-12-01

Our prior research has demonstrated that the intramolecular distribution of 15N within the N2O molecule can be used to distinguish N2O derived from nitrification and denitrification. For this approach to be successful, however, the affect of fractionation during consumption of N2O by denitrification must be understood. Stable isotope and isotopomer analysis of soil mesocosm experiments were used to investigate fractionation of N2O during consumption at four different levels of water filled pores space (WFPS) 60, 80, 100 and 110% Uncultivated soil from the Long Term Ecological Research Site at Kellogg Biological Station was used to establish that the fractionation factors for δ15N, δ18O-N2O, δ15Nα and δ15Nβ ranged from -4.2 to -7.8 ‰, -12.5 to -19.1 ‰,-5.3 to -9.7‰ and -2.0 to -6.0 ‰, respectively. Lower fractionation factors were observed at higher WFPS demonstrating the importance of diffusion in limiting the expression of fractionation. The small degree of fractionation for δ15Nα and δ15Nβ indicates that consumption must be marked (e.g. >50%) before a significant isotope effect is observed. Our characterization of fractionation factors as a function of WFPS provides a basis to apportion the origins of N2O even when consumption is evident.

Noninvasive optical quantification of absolute blood flow, blood oxygenation, and oxygen consumption rate in exercising skeletal muscle

NASA Astrophysics Data System (ADS)

Gurley, Katelyn; Shang, Yu; Yu, Guoqiang

2012-07-01

This study investigates a method using novel hybrid diffuse optical spectroscopies [near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS)] to obtain continuous, noninvasive measurement of absolute blood flow (BF), blood oxygenation, and oxygen consumption rate (\\Vdot O2) in exercising skeletal muscle. Healthy subjects (n=9) performed a handgrip exercise to increase BF and \\Vdot O2 in forearm flexor muscles, while a hybrid optical probe on the skin surface directly monitored oxy-, deoxy-, and total hemoglobin concentrations ([HbO2], [Hb], and THC), tissue oxygen saturation (StO2), relative BF (rBF), and relative oxygen consumption rate (r\\Vdot O2). The rBF and r\\Vdot O2 signals were calibrated with absolute baseline BF and \\Vdot O2 obtained through venous and arterial occlusions, respectively. Known problems with muscle-fiber motion artifacts in optical measurements during exercise were mitigated using a novel gating algorithm that determined muscle contraction status based on control signals from a dynamometer. Results were consistent with previous findings in the literature. This study supports the application of NIRS/DCS technology to quantitatively evaluate hemodynamic and metabolic parameters in exercising skeletal muscle and holds promise for improving diagnosis and treatment evaluation for patients suffering from diseases affecting skeletal muscle and advancing fundamental understanding of muscle and exercise physiology.

Noninvasive optical quantification of absolute blood flow, blood oxygenation, and oxygen consumption rate in exercising skeletal muscle

PubMed Central

Gurley, Katelyn; Shang, Yu

2012-01-01

Abstract. This study investigates a method using novel hybrid diffuse optical spectroscopies [near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS)] to obtain continuous, noninvasive measurement of absolute blood flow (BF), blood oxygenation, and oxygen consumption rate (V˙O2) in exercising skeletal muscle. Healthy subjects (n=9) performed a handgrip exercise to increase BF and V˙O2 in forearm flexor muscles, while a hybrid optical probe on the skin surface directly monitored oxy-, deoxy-, and total hemoglobin concentrations ([HbO2], [Hb], and THC), tissue oxygen saturation (StO2), relative BF (rBF), and relative oxygen consumption rate (rV˙O2). The rBF and rV˙O2 signals were calibrated with absolute baseline BF and V˙O2 obtained through venous and arterial occlusions, respectively. Known problems with muscle-fiber motion artifacts in optical measurements during exercise were mitigated using a novel gating algorithm that determined muscle contraction status based on control signals from a dynamometer. Results were consistent with previous findings in the literature. This study supports the application of NIRS/DCS technology to quantitatively evaluate hemodynamic and metabolic parameters in exercising skeletal muscle and holds promise for improving diagnosis and treatment evaluation for patients suffering from diseases affecting skeletal muscle and advancing fundamental understanding of muscle and exercise physiology. PMID:22894482

Induction by Bradyrhizobium diazoefficiens of Different Pathways for Growth in D-mannitol or L-arabinose Leading to Pronounced Differences in CO2 Fixation, O2 Consumption, and Lateral-Flagellum Production.

PubMed

Cogo, Carolina; Pérez-Giménez, Julieta; Rajeswari, Chandrasekar B; Luna, María F; Lodeiro, Aníbal R

2018-01-01

Bradyrhizobium diazoefficiens , a soybean N 2 -fixing symbiont, constitutes the basic input in one of the most prominent inoculant industries worldwide. This bacterium may be cultured with D-mannitol or L-arabinose as carbon-plus-energy source (C-source) with similar specific growth rates, but with higher biomass production with D-mannitol. To better understand the bacterium's carbon metabolism, we analyzed, by liquid chromatography and tandem mass spectrometry (MS), the whole set of proteins obtained from cells grown on each C-source. Among 3,334 proteins identified, 266 were overproduced in D-mannitol and 237 in L-arabinose, but among these, only 22% from D-mannitol cultures and 35% from L-arabinose cultures were annotated with well defined functions. In the D-mannitol-differential pool we found 19 enzymes of the pentose-phosphate and Calvin-Benson-Bassham pathways and accordingly observed increased extracellular-polysaccharide production by D-mannitol grown bacteria in a CO 2 -enriched atmosphere. Moreover, poly-3-hydroxybutyrate biosynthesis was increased, suggesting a surplus of reducing power. In contrast, the L-arabinose-differential pool contained 11 enzymes of the L-2-keto-3-deoxyarabonate pathway, 4 enzymes for the synthesis of nicotinamide-adenine dinucleotide from aspartate, with those cultures having a threefold higher O 2 -consumption rate than the D-mannitol cultures. The stoichiometric balances deduced from the modeled pathways, however, resulted in similar O 2 consumptions and ATP productions per C-mole of substrate. These results suggested higher maintenance-energy demands in L-arabinose, which energy may be used partly for flagella-driven motility. Since B. diazoefficiens produces the lateral-flagella system in only L-arabinose, we calculated the O 2 -consumption rates of a lafR ::Km mutant devoid of lateral flagella cultured in L-arabinose or D-mannitol. Contrary to that of the wild-type, the O 2 -consumption rate of this mutant was similar on

Chemometric analysis of the consumption of oral rinse chlorite (ClO2-) by human salivary biomolecules.

PubMed

Chang, Hubert; Blackburn, John; Grootveld, Martin

2013-12-01

Oral rinse formulations containing chlorite anion (ClO(2)(-)) as an active agent exert a range of valuable oral healthcare activities. However, salivary biomolecules which chemically react with this oxidant can, at least in principle, serve as potentially significant barriers to these therapeutic properties in the oral environment. Therefore, in this investigation, we have explored the extent of ClO(2)(-) consumption by biomolecules which scavenge this agent in human salivary supernatants (HSSs) in vitro. HSS samples were equilibrated with oral rinse formulations containing this active agent (30 s at 35 °C in order to mimic oral rinsing episodes). Differential spectrophotometric and ion-pair reversed-phase high-performance liquid chromatographic analyses were employed to determine residual ClO(2)(-) in these admixtures. Bioanalytical data acquired revealed the rapid consumption of ClO(2)(-) by biomolecular electron donors and/or antioxidants present in HSS samples. Mean ± 95 % confidence interval (CI) consumption levels of 7.14 ± 0.69 and 5.34 ± 0.69 % of the total ClO(2)(-) available were found for oral rinse products containing 0.10 and 0.40 % (w/v) ClO(2)(-), respectively. A mixed model analysis-of-variance performed on experimental data acquired demonstrated highly-significant differences between oral rinse ClO(2)(-) contents (p < 0.0001), trial participants (p < 0.001) and sampling days-within-participants (p < 0.001), and also revealed non-additive ClO(2)(-)-scavenging responses of participants' HSSs to increases in the oral rinse content of this oxidant (p < 0.0001). A slower, second phase of the reaction process (t (1/2) = 1.7-2.8 h) involved the oxidative consumption of salivary urate. These data clearly demonstrate that for recommended 30 s oral rinsing episodes performed at physiological temperature, <10 % of the total oral rinse ClO(2)(-) available is chemically and/or reductively consumed by HSS biomolecules for both

Quantitative 17O imaging towards oxygen consumption study in tumor bearing mice at 7 T.

PubMed

Narazaki, Michiko; Kanazawa, Yoko; Koike, Sachiko; Ando, Koichi; Ikehira, Hiroo

2013-06-01

(17)O magnetic resonance imaging (MRI) using a conventional pulse sequence was explored as a method of quantitative imaging towards regional oxygen consumption rate measurement for tumor evaluation in mice. At 7 T, fast imaging with steady state (FISP) was the best among gradient echo, fast spin echo and FISP for the purpose. The distribution of natural abundance H2(17)O in mice was visualized under spatial resolution of 2.5 × 2.5mm(2) by FISP in 10 min. The signal intensity by FISP showed a linear relationship with (17)O quantity both in phantom and mice. Following the injection of 5% (17)O enriched saline, (17)O re-distribution was monitored in temporal resolution down to 5 sec with an image quality sufficient to distinguish each organ. The image of labeled water produced from inhaled (17)O2 gas was also obtained. The present method provides quantitative (17)O images under sufficient temporal and spatial resolution for the evaluation of oxygen consumption rate in each organ. Experiments using various model compounds of R-OH type clarified that the signal contribution of body constituents other than water in the present in vivo(17)O FISP image was negligible. Copyright © 2013 Elsevier Inc. All rights reserved.

Oxygen consumption in weakly electric Neotropical fishes.

PubMed

Julian, David; Crampton, William G R; Wohlgemuth, Stephanie E; Albert, James S

2003-12-01

Weakly electric gymnotiform fishes with wave-type electric organ discharge (EOD) are less hypoxia-tolerant and are less likely to be found in hypoxic habitats than weakly electric gymnotiforms with pulse-type EOD, suggesting that differences in metabolism resulting from EOD type affects habitat choice. Although gymnotiform fishes are common in most Neotropical freshwaters and represent the dominant vertebrates in some habitats, the metabolic rates of these unique fishes have never been determined. In this study, O(2) consumption rates during EOD generation are reported for 34 gymnotiforms representing 23 species, all five families and 17 (59%) of the 28 genera. Over the size range sampled (0.4 g to 125 g), O(2) consumption of gymnotiform fishes was dependent on body mass, as expected, fitting a power function with a scaling exponent of 0.74, but the O(2) consumption rate was generally about 50% of that expected by extrapolation of temperate teleost metabolic rates to a similar ambient temperature (26 degrees C). O(2) consumption rate was not dependent on EOD type, but maintenance of "scan swimming" (continuous forwards and backwards swimming), which is characteristic only of gymnotiforms with wave-type EODs, increased O(2) consumption 2.83+/-0.49-fold (mean+/-SD). This suggests that the increased metabolic cost of scan swimming could restrict gymnotiforms with wave-type EODs from hypoxic habitats.

Nanoarchitectured Nb2O5 hollow, Nb2O5@carbon and NbO2@carbon Core-Shell Microspheres for Ultrahigh-Rate Intercalation Pseudocapacitors

NASA Astrophysics Data System (ADS)

Kong, Lingping; Zhang, Chuanfang; Wang, Jitong; Qiao, Wenming; Ling, Licheng; Long, Donghui

2016-02-01

Li-ion intercalation materials with extremely high rate capability will blur the distinction between batteries and supercapacitors. We construct a series of nanoarchitectured intercalation materials including orthorhombic (o-) Nb2O5 hollow microspheres, o-Nb2O5@carbon core-shell microspheres and tetragonal (t-) NbO2@carbon core-shell microspheres, through a one-pot hydrothermal method with different post-treatments. These nanoarchitectured materials consist of small nanocrystals with highly exposed active surface, and all of them demonstrate good Li+ intercalation pseudocapacitive properties. In particular, o-Nb2O5 hollow microspheres can deliver the specific capacitance of 488.3 F g-1, and good rate performance of 126.7 F g-1 at 50 A g-1. The o-Nb2O5@carbon core-shell microspheres show enhanced specific capacitance of 502.2 F g-1 and much improved rate performance (213.4 F g-1 at 50 A g-1). Furthermore, we demonstrate for the first time, t-NbO2 exhibits much higher rate capability than o-Nb2O5. For discharging time as fast as 5.9 s (50 A g-1), it still exhibits a very high specific capacitance of 245.8 F g-1, which is 65.2% retention of the initial capacitance (377.0 F g-1 at 1 A g-1). The unprecedented rate capability is an intrinsic feature of t-NbO2, which may be due to the conductive lithiated compounds.

Nanoarchitectured Nb2O5 hollow, Nb2O5@carbon and NbO2@carbon Core-Shell Microspheres for Ultrahigh-Rate Intercalation Pseudocapacitors

PubMed Central

Kong, Lingping; Zhang, Chuanfang; Wang, Jitong; Qiao, Wenming; Ling, Licheng; Long, Donghui

2016-01-01

Li-ion intercalation materials with extremely high rate capability will blur the distinction between batteries and supercapacitors. We construct a series of nanoarchitectured intercalation materials including orthorhombic (o-) Nb2O5 hollow microspheres, o-Nb2O5@carbon core-shell microspheres and tetragonal (t-) NbO2@carbon core-shell microspheres, through a one-pot hydrothermal method with different post-treatments. These nanoarchitectured materials consist of small nanocrystals with highly exposed active surface, and all of them demonstrate good Li+ intercalation pseudocapacitive properties. In particular, o-Nb2O5 hollow microspheres can deliver the specific capacitance of 488.3 F g−1, and good rate performance of 126.7 F g−1 at 50 A g−1. The o-Nb2O5@carbon core-shell microspheres show enhanced specific capacitance of 502.2 F g−1 and much improved rate performance (213.4 F g−1 at 50 A g−1). Furthermore, we demonstrate for the first time, t-NbO2 exhibits much higher rate capability than o-Nb2O5. For discharging time as fast as 5.9 s (50 A g−1), it still exhibits a very high specific capacitance of 245.8 F g−1, which is 65.2% retention of the initial capacitance (377.0 F g−1 at 1 A g−1). The unprecedented rate capability is an intrinsic feature of t-NbO2, which may be due to the conductive lithiated compounds. PMID:26880276

O2 reduction and denitrification rates in shallow aquifers

NASA Astrophysics Data System (ADS)

Tesoriero, Anthony J.; Puckett, Larry J.

2011-12-01

O2 reduction and denitrification rates were determined in shallow aquifers of 12 study areas representing a wide range in sedimentary environments and climatic conditions. Zero- and first-order rates were determined by relating reactant or product concentrations to apparent groundwater age. O2 reduction rates varied widely within and between sites, with zero-order rates ranging from <3 μmol L-1 yr-1 to more than 140 μmol L-1 yr-1 and first-order rates ranging from 0.02 to 0.27 yr-1. Moderate denitrification rates (10-100 μmol N L-1 yr-1; 0.06-0.30 yr-1) were observed in most areas with O2 concentrations below 60 μmol L-1, while higher rates (>100 μmol N L-1 yr-1; >0.36 yr-1) occur when changes in lithology result in a sharp increase in the supply of electron donors. Denitrification lag times (i.e., groundwater travel times prior to the onset of denitrification) ranged from <20 yr to >80 yr. The availability of electron donors is indicated as the primary factor affecting O2 reduction rates. Concentrations of dissolved organic carbon (DOC) and/or sulfate (an indicator of sulfide oxidation) were positively correlated with groundwater age at sites with high O2 reduction rates and negatively correlated at sites with lower rates. Furthermore, electron donors from recharging DOC are not sufficient to account for appreciable O2 and nitrate reduction. These relations suggest that lithologic sources of DOC and sulfides are important sources of electrons at these sites but surface-derived sources of DOC are not. A review of published rates suggests that denitrification tends to occur more quickly when linked with sulfide oxidation than with carbon oxidation.

O 2 reduction and denitrification rates in shallow aquifers

USGS Publications Warehouse

Tesoriero, A.J.; Puckett, L.J.

2011-01-01

O 2 reduction and denitrification rates were determined in shallow aquifers of 12 study areas representing a wide range in sedimentary environments and climatic conditions. Zero-and first-order rates were determined by relating reactant or product concentrations to apparent groundwater age. O 2 reduction rates varied widely within and between sites, with zero-order rates ranging from <3 ??mol L -1 yr -1 to more than 140 ??mol L -1 yr -1 and first-order rates ranging from 0.02 to 0.27 yr -1. Moderate denitrification rates (10-100 ??mol N L -1 yr -1; 0.06-0.30 yr -1) were observed in most areas with O 2 concentrations below 60 mol L -1, while higher rates (>100 mol N L -1 yr -1; >0.36 yr -1) occur when changes in lithology result in a sharp increase in the supply of electron donors. Denitrification lag times (i.e., groundwater travel times prior to the onset of denitrification) ranged from <20 yr to >80 yr. The availability of electron donors is indicated as the primary factor affecting O 2 reduction rates. Concentrations of dissolved organic carbon (DOC) and/or sulfate (an indicator of sulfide oxidation) were positively correlated with groundwater age at sites with high O 2 reduction rates and negatively correlated at sites with lower rates. Furthermore, electron donors from recharging DOC are not sufficient to account for appreciable O 2 and nitrate reduction. These relations suggest that lithologic sources of DOC and sulfides are important sources of electrons at these sites but surface-derived sources of DOC are not. A review of published rates suggests that denitrification tends to occur more quickly when linked with sulfide oxidation than with carbon oxidation. copyright 2011 by the American Geophysical Union.

[Oxygen consumption rate of Sepia pharaonis embryos.

PubMed

Wang, Peng Shuai; Jiang, Xia Min; Ruan, Peng; Peng, Rui Bing; Jiang, Mao Wang; Han, Qing Xi

2016-07-01

This research was conducted to unravel the variation of oxygen consumption rate during different developmental stages and the effects of different ecological factors on embryonic oxygen consumption rate of Sepia pharaonis. The oxygen consumption rates were measured at twelve deve-lopmental stages by the sealed volumetric flasks, and four embryonic developmental periods (oosperm, gastrula, the formation of organization, endoskeleton) were selected under various ecological conditions, such as salinity (21, 24, 27, 30, 33), water temperature (18, 21, 24, 27, 30 ℃) and pH (7.0, 7.5, 8.0, 8.5, 9.0). The results showed that the oxygen consumption rate rose along with the developmental progress, and distinctly differed from each other. The oxygen consumption rate was 0.082 mg·(100 eggs) -1 ·h -1 during oosperm period, and rose to 0.279 mg·(100 eggs) -1 ·h -1 during gastrula period, which was significantly higher than that of blastula period. Finally, the oxygen consumption rate rose to 1.367 mg·(100 eggs) -1 ·h -1 during hatching period. The salinity showed a significant effect on oxygen consumption rate during the formation of organization and endoskeleton formation stage (P<0.05), but no significant effect during oosperm and gastrula periods (P>0.05). The oxygen consumption rates of four studied embryonic stages all rose and then declined along with the increase of salinity, and reached the highest values [0.082, 0.200, 0.768 and 1.301 mg·(100 eggs) -1 ·h -1 , respectively] at salinity 30. The water temperature had a significant effect on the embryo oxygen consumption rates of gastrula, and the formation of organization and endoskeleton formation stage (P<0.05), with the exception of oosperm (P>0.05). The oxygen consumption rates of four studied embryonic stages all rose and then declined along with the increase of temperature, and reached the highest values at 27 ℃ [0.082, 0.286, 0.806 and 1.338 mg·(100 eggs) -1 ·h -1 , respectively]. The pH had no

Diffusion and Monod kinetics model to determine in vivo human corneal oxygen-consumption rate during soft contact lens wear.

PubMed

Del Castillo, Luis F; da Silva, Ana R Ferreira; Hernández, Saul I; Aguilella, M; Andrio, Andreu; Mollá, Sergio; Compañ, Vicente

2015-01-01

We present an analysis of the corneal oxygen consumption Qc from non-linear models, using data of oxygen partial pressure or tension (P(O2) ) obtained from in vivo estimation previously reported by other authors. (1) METHODS: Assuming that the cornea is a single homogeneous layer, the oxygen permeability through the cornea will be the same regardless of the type of lens that is available on it. The obtention of the real value of the maximum oxygen consumption rate Qc,max is very important because this parameter is directly related with the gradient pressure profile into the cornea and moreover, the real corneal oxygen consumption is influenced by both anterior and posterior oxygen fluxes. Our calculations give different values for the maximum oxygen consumption rate Qc,max, when different oxygen pressure values (high and low P(O2)) are considered at the interface cornea-tears film. Present results are relevant for the calculation on the partial pressure of oxygen, available at different depths into the corneal tissue behind contact lenses of different oxygen transmissibility. Copyright © 2014. Published by Elsevier Espana.

Diffusion and Monod kinetics model to determine in vivo human corneal oxygen-consumption rate during soft contact lens wear

PubMed Central

Del Castillo, Luis F.; da Silva, Ana R. Ferreira; Hernández, Saul I.; Aguilella, M.; Andrio, Andreu; Mollá, Sergio; Compañ, Vicente

2014-01-01

Purpose We present an analysis of the corneal oxygen consumption Qc from non-linear models, using data of oxygen partial pressure or tension (pO2) obtained from in vivo estimation previously reported by other authors.1 Methods Assuming that the cornea is a single homogeneous layer, the oxygen permeability through the cornea will be the same regardless of the type of lens that is available on it. The obtention of the real value of the maximum oxygen consumption rate Qc,max is very important because this parameter is directly related with the gradient pressure profile into the cornea and moreover, the real corneal oxygen consumption is influenced by both anterior and posterior oxygen fluxes. Results Our calculations give different values for the maximum oxygen consumption rate Qc,max, when different oxygen pressure values (high and low pO2) are considered at the interface cornea-tears film. Conclusion Present results are relevant for the calculation on the partial pressure of oxygen, available at different depths into the corneal tissue behind contact lenses of different oxygen transmissibility. PMID:25649636

Is rate-pressure product of any use in the isolated rat heart? Assessing cardiac 'effort' and oxygen consumption in the Langendorff-perfused heart.

PubMed

Aksentijević, Dunja; Lewis, Hannah R; Shattock, Michael J

2016-02-01

What is the central question of this study? Rate-pressure product (RPP) is commonly used as an index of cardiac 'effort'. In canine and human hearts (which have a positive force-frequency relationship), RPP is linearly correlated with oxygen consumption and has therefore been widely adopted as a species-independent index of cardiac work. However, given that isolated rodent hearts demonstrate a negative force-frequency relationship, its use in this model requires validation. What is the main finding and its importance? Despite its widespread use, RPP is not correlated with oxygen consumption (or cardiac 'effort') in the Langendorff-perfused isolated rat heart. This lack of correlation was also evident when perfusions included a range of metabolic substrates, insulin or β-adrenoceptor stimulation. Langendorff perfusion of hearts isolated from rats and mice has been used extensively for physiological, pharmacological and biochemical studies. The ability to phenotype these hearts reliably is, therefore, essential. One of the commonly used indices of function is rate-pressure product (RPP); a rather ill-defined index of 'work' or, more correctly, 'effort'. Rate-pressure product, as originally described in dog or human hearts, was shown to be correlated with myocardial oxygen consumption (MV̇O2). Despite its widespread use, the application of this index to rat or mouse hearts (which, unlike the dog or human, have a negative force-frequency relationship) has not been characterized. The aim of this study was to examine the relationship between RPP and MV̇O2 in Langendorff-perfused rat hearts. Paced hearts (300-750 beats min(-1)) were perfused either with Krebs-Henseleit (KH) buffer (11 mm glucose) or with buffer supplemented with metabolic substrates and insulin. The arteriovenous oxygen consumption (MV̇O2) was recorded. Metabolic status was assessed using (31) P magnetic resonance spectroscopy and lactate efflux. Experiments were repeated in the presence of

Rate Coefficient Measurements of the Reaction CH3 + O2 = CH3O + O

NASA Technical Reports Server (NTRS)

Hwang, S. M.; Ryu, Si-Ok; DeWitt, K. J.; Rabinowitz, M. J.

1999-01-01

Rate coefficients for the reaction CH3 + O2 = CH3O + O were measured behind reflected shock waves in a series of lean CH4-O2-Ar mixtures using hydroxyl and methyl radical diagnostics. The rate coefficients are well represented by an Arrhenius expression given as k = (1.60(sup +0.67, sub -0.47 ) x 10(exp 13) e(-15813 +/- 587 K/T)/cubic cm.mol.s. This expression, which is valid in the temperature range 1575-1822 K, supports the downward trend in the rate coefficients that has been reported in recent determinations. All measurements to date, including the present study, have been to some extent affected by secondary reactions. The complications due to secondary reactions, choice of thermochemical data, and shock-boundary layer interactions that affect the determination of the rate coefficients are examined.

Rate Coefficient Measurements of the Reaction CH3+O2+CH3O+O

NASA Technical Reports Server (NTRS)

Hwang, S. M.; Ryu, Si-Ok; DeWitt, K. J.; Rabinowitz, M. J.

1999-01-01

Rate coefficients for the reaction CH3 + O2 = CH3O + O were measured behind reflected shock waves in a series of lean CH4-O2-Ar mixtures using hydroxyl and methyl radical diagnostics. The rate coefficients are well represented by an Arrhenius expression given as k = (1.60(sup +0.67, -0.47)) X 10(exp 13) exp(- 15813 +/- 587 K/T)cc/mol s. This expression, which is valid in the temperature range 1575-1822 K, supports the downward trend in the rate coefficients that has been reported in recent determinations. All measurements to date, including the present study, have been to some extent affected by secondary reactions. The complications due to secondary reactions, choice of thermochemical data, and shock-boundary layer interactions that affect the determination of the rate coefficients are examined.

A procedure for the measurement of Oxygen Consumption Rates (OCRs) in red wines and some observations about the influence of wine initial chemical composition.

PubMed

Marrufo-Curtido, Almudena; Carrascón, Vanesa; Bueno, Mónica; Ferreira, Vicente; Escudero, Ana

2018-05-15

The rates at which wine consumes oxygen are important technological parameters for whose measurement there are not accepted procedures. In this work, volumes of 8 wines are contacted with controlled volumes of air in air-tight tubes containing oxygen-sensors and are further agitated at 25 °C until O 2 consumption is complete. Three exposure levels of O 2 were used: low (10 mg/L) and medium or high (18 or 32 mg/L plus the required amount to oxidize all wine SO 2 ). In each oxygen level, 2-4 independent segments following pseudo-first order kinetics were identified, plus an initial segment at which wine consumed O 2 very fast. Overall, multivariate data techniques identify six different Oxygen-Consumption-Rates (OCRs) as required to completely define wine O 2 consumption. Except the last one, all could be modeled from the wine initial chemical composition. Total acetaldehyde, Mn, Cu/Fe, blue and red pigments and gallic acid seem to be essential to determine these OCRs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Characterization and production and consumption processes of N2O emitted from temperate agricultural soils determined via isotopomer ratio analysis

NASA Astrophysics Data System (ADS)

Toyoda, Sakae; Yano, Midori; Nishimura, Sei-Ichi; Akiyama, Hiroko; Hayakawa, Atsushi; Koba, Keisuke; Sudo, Shigeto; Yagi, Kazuyuki; Makabe, Akiko; Tobari, Yoshifumi; Ogawa, Nanako O.; Ohkouchi, Naohiko; Yamada, Keita; Yoshida, Naohiro

2011-06-01

Isotopomer ratios of N2O (bulk nitrogen and oxygen isotope ratios, δ15Nbulk and δ18O, and intramolecular 15N site preference, SP) are useful parameters that characterize sources of this greenhouse gas and also provide insight into production and consumption mechanisms. We measured isotopomer ratios of N2O emitted from typical Japanese agricultural soils (Fluvisols and Andisols) planted with rice, wheat, soybean, and vegetables, and treated with synthetic (urea or ammonium) and organic (poultry manure) fertilizers. The results were analyzed using a previously reported isotopomeric N2O signature produced by nitrifying/denitrifying bacteria and a characteristic relationship between δ15Nbulk and SP during N2O reduction by denitrifying bacteria. Relative contributions from nitrification (hydroxylamine oxidation) and denitrification (nitrite reduction) to gross N2O production deduced from the analysis depended on soil type and fertilizer. The contribution from nitrification was relatively high (40%-70%) in Andisols amended with synthetic ammonium fertilizer, while denitrification was dominant (50%-90%) in the same soils amended with poultry manure during the period when N2O production occurred in the surface layer. This information on production processes is in accordance with that obtained from flux/concentration analysis of N2O and soil inorganic nitrogen. However, isotopomer analysis further revealed that partial reduction of N2O was pronounced in high-bulk density, alluvial soil (Fluvisol) compared to low-bulk density, volcanic ash soil (Andisol), and that the observed difference in N2O flux between normal and pelleted manure could have resulted from a similar mechanism with different rates of gross production and gross consumption. The isotopomeric analysis is based on data from pure culture bacteria and would be improved by further studies on in situ biological processes in soils including those by fungi. When flux/concentration-weighted average isotopomer

Estimation of the rate of oxygen consumption of the common eider duck (Somateria mollissima), with some measurements of heart rate during voluntary dives.

PubMed

Hawkins, P A; Butler, P J; Woakes, A J; Speakman, J R

2000-09-01

The relationship between heart rate (f(H)) and rate of oxygen consumption (V(O2)) was established for a marine diving bird, the common eider duck (Somateria mollissima), during steady-state swimming and running exercise. Both variables increased exponentially with speed during swimming and in a linear fashion during running. Eleven linear regressions of V(O2) (ml kg(-1 )min(-1)) on f(H) (beats min(-1)) were obtained: five by swimming and six by running the birds. The common regression was described by V(O2)=10.1 + 0.15f(H) (r(2)=0.46, N=272, P<0.0001). The accuracy of this relationship for predicting mean V(O2) was determined for a group of six birds by recording f(H) continuously over a 2-day period and comparing estimated V(O2) obtained using the common regression with (i) V(O2) estimated using the doubly labelled water technique (DLW) and (ii) V(O2) measured using respirometry. A two-pool model produced the most accurate estimated V(O2) using DLW. Because of individual variability within mean values of V(O2) estimated using both techniques, there was no significant difference between mean V(O2) estimated using f(H) or DLW and measured V(O2) values (P>0.2), although individual errors were substantially less when f(H) was used rather than DLW to estimate V(O2). Both techniques are, however, only suitable for estimating mean V(O2) for a group of animals, not for individuals. Heart rate and behaviour were monitored during a bout of 63 voluntary dives by one female bird in an indoor tank 1.7 m deep. Tachycardia occurred both in anticipation of and following each dive. Heart rate decreased before submersion but was above resting values for the whole of the dive cycle. Mean f(H) at mean dive duration was significantly greater than f(H) while swimming at maximum sustainable surface speeds. Heart rate was used to estimate mean V(O2) during the dive cycle and to predict aerobic dive limit (ADL) for shallow dives.

Oxygen consumption during pouch development of the macropod marsupial Setonix brachyurus

PubMed Central

Shield, John

1966-01-01

1. Measurements of O2 consumption at 9 or 10 temperatures in the 20-40° C ambient temperature range were made on joeys with ages selected to cover the 180-day period of pouch occupancy. 2. The rate of O2 consumption of joeys younger than 100 days increased directly with ambient temperature. 3. After 100 days of age the O2 consumption rate at low temperatures rose and at about 140 days of age a constant rate was maintained over the full ambient temperature range. 4. Heat transfer from joey to mother commenced after 100 days of age. 5. At 150-180 days of age the rate of O2 consumption at 20° C was approximately 12 times greater than at ages less than 100 days. A thermal neutral zone was established in the range 32-36° C by joeys older than 150 days. 6. At the usual pouch temperature of 36·5° C, O2 consumption per unit wet body weight rose from 12 ml./kg.min at birth to 17 ml./kg.min at the end of pouch life. On a unit dry body weight basis it fell from 120 to 56 ml./kg.min. This decline parallels the decrease in growth rate. PMID:5972171

Maximization of current efficiency for organic pollutants oxidation at BDD, Ti/SnO2-Sb/PbO2, and Ti/SnO2-Sb anodes.

PubMed

Xing, Xuan; Ni, Jinren; Zhu, Xiuping; Jiang, Yi; Xia, Jianxin

2018-08-01

Whereas electrochemical oxidation is noted for its ability to degrade bio-refractory organics, it has also been incorrectly criticized for excessive energy consumption. The present paper rectifies this misunderstanding by demonstrating that the energy actually consumed in the degradation process is much less than that wasted in the side reaction of oxygen evolution. To minimize the side reaction, the possible highest instantaneous current efficiency (PHICE) for electrochemical oxidation of phenol at Boron-doped Diamond (BDD), Ti/SnO 2 -Sb/PbO 2 (PbO 2 ), and Ti/SnO 2 -Sb (SnO 2 ) anodes has been investigated systematically, and found to reach almost 100% at the BDD anode compared with 23% at the PbO 2 anode and 9% at the SnO 2 anode. The significant discrepancy between PHICE values at the various anodes is interpreted in terms of different existing forms of hydroxyl radicals. For each anode system, the PHICEs are maintained experimentally using a computer-controlled exponential decay current mode throughout the electrolysis process. For applications, the minimized energy consumption is predicted by response surface methodology, and demonstrated for the BDD anode system. Consequently, almost 100% current efficiency is achieved (for a relatively meagre energy consumption of 17.2 kWh kgCOD -1 ) along with excellent COD degradation efficiency by optimizing the initial current density, flow rate, electrolysis time, and exponential decay constant. Compared with galvanostatic conditions, over 70% of the energy is saved in the present study, thus demonstrating the great potential of electrochemical oxidation for practical applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

MEMS-Based Gas Sensor Using PdO-Decorated TiO2 Thin Film for Highly Sensitive and Selective H2 Detection with Low Power Consumption

NASA Astrophysics Data System (ADS)

Kwak, Seungmin; Shim, Young-Seok; Yoo, Yong Kyoung; Lee, Jin-Hyung; Kim, Inho; Kim, Jinseok; Lee, Kyu Hyoung; Lee, Jeong Hoon

2018-03-01

We report a micromachined H2 sensor that is composed of a Pt micro-heater, low-stress insulating layer (SiO2/SiNx/SiO2), Pt-interdigitated electrodes, and gas sensing materials. Three types of Pt micro-heater are designed as function of electrode width, and their thermal properties are systematically analyzed by finite element modeling FEM with infrared camera. The power consumptions when the surface temperature reached 150, 200, 250, and 300 °C are calculated to approximately 33, 48, 67 and 85 mW, respectively. The response of the PdO nanoparticles-decorated TiO2 thin films to H2 is much higher than those of other gases such as CH4 and CO at 200 °C (48 mW). Further, the response time is reduced to approximately 3 s. The enhancement of gas sensing properties is related to well-designed micro-heater and catalytic effects of PdO nanoparticles such as electronic and chemical sensitization. These results suggest that the PdO nanoparticles-decorated TiO2 thin film, namely MEMS-based H2 sensors are very promising for use in IoT application to improve the quality of human's life.

MEMS-Based Gas Sensor Using PdO-Decorated TiO2 Thin Film for Highly Sensitive and Selective H2 Detection with Low Power Consumption

NASA Astrophysics Data System (ADS)

Kwak, Seungmin; Shim, Young-Seok; Yoo, Yong Kyoung; Lee, Jin-Hyung; Kim, Inho; Kim, Jinseok; Lee, Kyu Hyoung; Lee, Jeong Hoon

2018-05-01

We report a micromachined H2 sensor that is composed of a Pt micro-heater, low-stress insulating layer (SiO2/SiNx/SiO2), Pt-interdigitated electrodes, and gas sensing materials. Three types of Pt micro-heater are designed as function of electrode width, and their thermal properties are systematically analyzed by finite element modeling FEM with infrared camera. The power consumptions when the surface temperature reached 150, 200, 250, and 300 °C are calculated to approximately 33, 48, 67 and 85 mW, respectively. The response of the PdO nanoparticles-decorated TiO2 thin films to H2 is much higher than those of other gases such as CH4 and CO at 200 °C (48 mW). Further, the response time is reduced to approximately 3 s. The enhancement of gas sensing properties is related to well-designed micro-heater and catalytic effects of PdO nanoparticles such as electronic and chemical sensitization. These results suggest that the PdO nanoparticles-decorated TiO2 thin film, namely MEMS-based H2 sensors are very promising for use in IoT application to improve the quality of human's life.

Vodka and violence: alcohol consumption and homicide rates in Russia.

PubMed

Pridemore, William Alex

2002-12-01

In Russia, rates of alcohol consumption and homicide are among the highest in the world, and already-high levels increased dramatically after the breakup of the Soviet Union. Rates of both, however, vary greatly among Russia's 89 regions. We took advantage of newly available vital statistics and socioeconomic data to examine the regional covariation of drinking and lethal violence. Log-log models were employed to estimate the impact of alcohol consumption on regional homicide rates, controlling for structural factors thought to influence the spatial distribution of homicide rates. Results revealed a positive and significant relationship between alcohol consumption and homicide, with a 1% increase in regional consumption of alcohol associated with an approximately 0.25% increase in homicide rates. In Russia, higher regional rates of alcohol consumption are associated with higher rates of homicide.

Vodka and Violence: Alcohol Consumption and Homicide Rates in Russia

PubMed Central

Pridemore, William Alex

2002-01-01

In Russia, rates of alcohol consumption and homicide are among the highest in the world, and already-high levels increased dramatically after the breakup of the Soviet Union. Rates of both, however, vary greatly among Russia’s 89 regions. We took advantage of newly available vital statistics and socioeconomic data to examine the regional covariation of drinking and lethal violence. Log-log models were employed to estimate the impact of alcohol consumption on regional homicide rates, controlling for structural factors thought to influence the spatial distribution of homicide rates. Results revealed a positive and significant relationship between alcohol consumption and homicide, with a 1% increase in regional consumption of alcohol associated with an approximately 0.25% increase in homicide rates. In Russia, higher regional rates of alcohol consumption are associated with higher rates of homicide. PMID:12453810

Temperature Dependence of the O + HO2 Rate Coefficient

NASA Technical Reports Server (NTRS)

Nicovich, J. M.; Wine, P. H.

1997-01-01

A pulsed laser photolysis technique has been employed to investigate the kinetics of the radical-radical reaction O((sup 3)P) + HO2 OH + O2 over the temperature range 266-391 K in 80 Torr of N2 diluent gas. O((sup 3)P) was produced by 248.5-nm KrF laser photolysis of O3 followed by rapid quenching of O(1D) to O((sup 3)P) while HO2 was produced by simultaneous photolysis of H2O2 to create OH radicals which, in turn, reacted with H2O2 to yield HO2. The O((sup 3)P) temporal profile was monitored by using time-resolved resonance fluorescence spectroscopy. The HO2 concentration was calculated based on experimentally measured parameters. The following Arrhenius expression describes our experimental results: k(sub 1)(T) equals (2.91 +/- 0.70) x 10(exp -11) exp[(228 +/- 75)/T] where the errors are 2 sigma and represent precision only. The absolute uncertainty in k, at any temperature within the range 266-391 K is estimated to be +/- 22 percent. Our results are in excellent agreement with a discharge flow study of the temperature dependence of k(sub 1) in 1 Torr of He diluent reported by Keyser, and significantly reduce the uncertainty in the rate of this important stratospheric reaction at subambient temperatures.

A Stirred Microchamber for Oxygen Consumption Rate Measurements With Pancreatic Islets

PubMed Central

Papas, Klearchos K.; Pisania, Anna; Wu, Haiyan; Weir, Gordon C.; Colton, Clark K.

2010-01-01

Improvements in pancreatic islet transplantation for treatment of diabetes are hindered by the absence of meaningful islet quality assessment methods. Oxygen consumption rate (OCR) has previously been used to assess the quality of organs and primary tissue for transplantation. In this study, we describe and characterize a stirred microchamber for measuring OCR with small quantities of islets. The device has a titanium body with a chamber volume of about 200 µL and is magnetically stirred and water jacketed for temperature control. Oxygen partial pressure (pO2) is measured by fluorescence quenching with a fiber optic probe, and OCR is determined from the linear decrease of pO2 with time. We demonstrate that measurements can be made rapidly and with high precision. Measurements with βTC3 cells and islets show that OCR is directly proportional to the number of viable cells in mixtures of live and dead cells and correlate linearly with membrane integrity measurements made with cells that have been cultured for 24 h under various stressful conditions. PMID:17497731

H2/O2 three-body rates at high temperatures

NASA Technical Reports Server (NTRS)

Marinelli, William J.; Kessler, William J.; Piper, Lawrence G.; Rawlins, W. Terry

1990-01-01

The extraction of thrust from air breathing hypersonic propulsion systems is critically dependent on the degree to which chemical equilibrium is reached in the combustion process. In the combustion of H2/Air mixtures, slow three-body chemical reactions involving H-atoms, O-atoms, and the OH radical play an important role in energy extraction. A first-generation high temperature and pressure flash-photolysis/laser-induced fluorescence reactor was designed and constructed to measure these important three-body rates. The system employs a high power excimer laser to produce these radicals via the photolysis of stable precursors. A novel two-photon laser-induced fluorescence technique is employed to detect H-atoms without optical thickness or O2 absorption problems. To demonstrate the feasibility of the technique the apparatus in the program is designed to perform preliminary measurements on the H + O2 + M reaction at temperatures from 300 to 835 K.

High rate dry etching of InGaZnO by BCl3/O2 plasma

NASA Astrophysics Data System (ADS)

Park, Wanjae; Whang, Ki-Woong; Gwang Yoon, Young; Hwan Kim, Jeong; Rha, Sang-Ho; Seong Hwang, Cheol

2011-08-01

This paper reports the results of the high-rate dry etching of indium gallium zinc oxide (IGZO) at room temperature using BCl3/O2 plasma. We achieved an etch rate of 250 nm/min. We inferred from the x-ray photoelectron spectroscopy analysis that BOx or BOClx radicals generated from BCl3/O2 plasma cause the etching of the IGZO material. O2 initiates the etching of IGZO, and Ar removes nonvolatile byproducts from the surface during the etching process. Consequently, a smooth etched surface results when these gases are added to the etch gas.

Rate constant for the reaction SO + BrO yields SO2 + Br

NASA Technical Reports Server (NTRS)

Brunning, J.; Stief, L.

1986-01-01

The rate of the radical-radical reaction SO + BrO yields SO2 + Br has been determined at 298 K in a discharge flow system near 1 torr pressure with detection of SO and BrO via collision-free sampling mass spectrometry. The rate constant was determined using two different methods: measuring the decay of SO radicals in the presence of an excess of BrO and measuring the decay of BrO radicals in excess SO. The results from the two methods are in reasonable agreement and the simple mean of the two values gives the recommended rate constant at 298 K, k = (5.7 + or - 2.0) x 10 to the -11th cu cm/s. This represents the first determination of this rate constant and it is consistent with a previously derived lower limit based on SO2 formation. Comparison is made with other radical-radical reactions involving SO or BrO. The reaction SO + BrO yields SO2 + Br is of interest for models of the upper atmosphere of the earth and provides a potential coupling between atmospheric sulfur and bromine chemistry.

Heating rate effects in simulated liquid Al2O_3

NASA Astrophysics Data System (ADS)

van Hoang, Vo

2006-01-01

The heating rate effects in simulated liquid Al{2}O{3} have been investigated by Molecular Dynamics (MD) method. Simulations were done in the basic cube under periodic boundary conditions containing 3000 ions with Born-Mayer type pair potentials. The temperature of the system was increasing linearly in time from the zero temperature as T(t)=T0 +γ t, where γ is the heating rate. The heating rate dependence of density and enthalpy of the system was found. Calculations show that static properties of the system such as the coordination number distributions and bond-angle distributions slightly depend on γ . Structure of simulated amorphous Al{2}O{3} model with the real density at the ambient pressure is in good agreement with Lamparter's experimental data. The heating rate dependence of dynamics of the system has been studied through the diffusion constant, mean-squared atomic displacement and comparison of partial radial distribution functions (PRDFs) for 10% most mobile and immobile particles with the corresponding mean ones. Finally, the evolution of diffusion constant of Al and O particles and structure of the system upon heating for the smallest heating rate was studied and presented. And we find that the temperature dependence of self-diffusion constant in the high temperature region shows a crossover to one which can be described well by a power law, D∝ (T-Tc )^γ . The critical temperature Tc is about 3500 K and the exponent γ is close to 0.941 for Al and to 0.925 for O particles. The glass phase transition temperature Tg for the Al{2}O{3} system is at anywhere around 2000 K.

MnO2 Motor: A Prospective Cancer-Starving Therapy Promoter.

PubMed

Zhang, Yao-Hui; Qiu, Wen-Xiu; Zhang, Mingkang; Zhang, Lu; Zhang, Xian-Zheng

2018-05-02

Here, a tumor-targeted MnO 2 motor nanosystem (designed as MG/HA) was constructed by the assembly of glucose oxidase (GOD), manganese dioxide (MnO 2 ), and glycoprotein CD44-targeting polymer hyaluronic acid (HA) to elevate cancer-starving therapy efficacy in solid tumor. Upon the specific uptake of MG/HA by CD44 overexpressed cancer cells, GOD catalyzed the oxidation of glucose into gluconic acid and hydrogen peroxide (H 2 O 2 ) accompanying the consumption of oxygen (O 2 ). Meanwhile, MnO 2 would react with H 2 O 2 and acid to generate O 2 , which is in turn supplied to the glucose-depletion process, running like a loop. As a result, MnO 2 is displayed as a motor to promote the rate of glucose depletion that contributed to the starving therapy. In contrast to G/HA, MG/HA could not only achieve effective glucose consumption to depress cancer progression, but also alleviate hypoxia and reduce the expression of Glut1 to inhibit the metabolism for further restraining the tumor aggressiveness and metastasis. The concept of MnO 2 motor shows a promising prospect to overcome the restriction of the starving therapy.

Correlation of FMISO simulations with pimonidazole-stained tumor xenografts: A question of O{sub 2} consumption?

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

Wack, L. J., E-mail: linda-jacqueline.wack@med.uni

Purpose: To compare a dedicated simulation model for hypoxia PET against tumor microsections stained for different parameters of the tumor microenvironment. The model can readily be adapted to a variety of conditions, such as different human head and neck squamous cell carcinoma (HNSCC) xenograft tumors. Methods: Nine different HNSCC tumor models were transplanted subcutaneously into nude mice. Tumors were excised and immunoflourescently labeled with pimonidazole, Hoechst 33342, and CD31, providing information on hypoxia, perfusion, and vessel distribution, respectively. Hoechst and CD31 images were used to generate maps of perfused blood vessels on which tissue oxygenation and the accumulation of themore » hypoxia tracer FMISO were mathematically simulated. The model includes a Michaelis–Menten relation to describe the oxygen consumption inside tissue. The maximum oxygen consumption rate M{sub 0} was chosen as the parameter for a tumor-specific optimization as it strongly influences tracer distribution. M{sub 0} was optimized on each tumor slice to reach optimum correlations between FMISO concentration 4 h postinjection and pimonidazole staining intensity. Results: After optimization, high pixel-based correlations up to R{sup 2} = 0.85 were found for individual tissue sections. Experimental pimonidazole images and FMISO simulations showed good visual agreement, confirming the validity of the approach. Median correlations per tumor model varied significantly (p < 0.05), with R{sup 2} ranging from 0.20 to 0.54. The optimum maximum oxygen consumption rate M{sub 0} differed significantly (p < 0.05) between tumor models, ranging from 2.4 to 5.2 mm Hg/s. Conclusions: It is feasible to simulate FMISO distributions that match the pimonidazole retention patterns observed in vivo. Good agreement was obtained for multiple tumor models by optimizing the oxygen consumption rate, M{sub 0}, whose optimum value differed significantly between tumor models.« less

Fertilizer consumption trend in developing countries vs. developed countries.

PubMed

Motesharezadeh, Babak; Etesami, Hassan; Bagheri-Novair, Sepideh; Amirmokri, Hormoz

2017-03-01

The study of the chemical fertilizer consumption in different countries provides basal data for the decision-making of fertilizer production and for the environmental impact assessment of fertilizer application. Hence, the aim of this research was to study and compare the trend of the chemical fertilizer consumption from 1980 to 2012 in Iran, Turkey, Japan, Germany, France, and the USA. For this purpose, various indices such as application rates (kg ha -1 ) of N, P, and K, arable land, and total fertilizer consumption were analysed. Results showed that the application rates of nutrients (N-P 2 O 5 -K 2 O) in Iran, Turkey, Japan, Germany, France, and the USA in 2012 were 100-42-7, 100-42-7, 100-94-60, 100-17-25, 100-13-38, and 100-33-35, respectively. The lowest and highest area under production were observed in Japan with 4.0 million ha (0.033 ha/person) and in the USA with 155.0 million ha (0.51 ha/person) during 2008-2015, respectively. In addition, the highest and lowest application rates of net nutrient consumption were recorded in France and Germany (285 and 285 kg ha -1 ) and in Iran (66 kg ha -1 ), respectively. Overall, the average net consumption of fertilizers in the studied countries in three recent decades (million tonnes) decreased in the order: the USA (19.282) > France (4.601) > Germany (3.302) > Turkey (1.825) > Japan (1.604) > Iran (1.130). Regarding an estimated 9.2 billion people by 2050, the balanced consumption of nutrients (N-P 2 O 5 -K 2 O) and the principles of optimal consumption of fertilizers are keys for achieving the increased food production, food security, and environmental conservation.

Nitrous oxide production and consumption by denitrification in a grassland: Effects of grazing and hydrology.

PubMed

Hu, Jing; Inglett, Kanika S; Clark, Mark W; Inglett, Patrick W; Ramesh Reddy, K

2015-11-01

Denitrification is generally recognized as a major mechanism contributing to nitrous oxide (N2O) production, and is the only known biological process for N2O consumption. Understanding factors controlling N2O production and consumption during denitrification will provide insights into N2O emission variability, and potentially predict capacity of soils to serve as sinks or sources of N2O. This study investigated the effects of hydrology and grazing on N2O production and consumption in a grassland based agricultural watershed. A batch incubation study was conducted on soils (0-10 cm) collected along a hydrological gradient representing isolated wetland (Center), transient zone (Edge) and pasture upland (Upland), from both grazed and ungrazed areas. Production and consumption potentials of N2O were quantified on soils under four treatments, including (i) ambient condition, and amended with (ii) NO3(-), (iii) glucose-C, and (iv) NO3(-) +glucose-C. The impacts of grazing on N2O production and consumption were not observed. Soils in hydrologically distinct zones responded differently to N2O production and consumption. Under ambient conditions, both production and consumption rates of Edge soils were higher than those observed for Center and Upland soils. Results of amended incubations suggested NO3(-) was a key factor limiting N2O production and consumption rates in all hydrological zones. Over 5-d incubation with NO3(-) amendment, cumulative production and consumption of N2O for Center soils were 1.6 and 3.3 times higher than Edge soils, and 3.6 and 7.6 times higher than Upland soils, respectively. However, cumulative N2O net production for Edge soils was the highest, with 2 to 3 times higher than Upland and Center soils. Our results suggest that the transient areas between wetland and upland are likely to be "hot spots" of N2O emissions in this ecosystem. Wetlands within agricultural landscapes can potentially function to reduce both NO3(-) leaching and N2O emissions

The rate of sulfide oxidation by δMnO 2 in seawater

NASA Astrophysics Data System (ADS)

Yao, Wensheng; Millero, Frank J.

1993-07-01

The rate of oxidation of hydrogen sulfide by manganese dioxide in seawater was determined as a function of pH (2.0-9.0), temperature (5-45°C), and ionic strength (0-4 M). The overall rate constant, k, in seawater at pH = 8.17 was found to be first order with respect to both sulfide and manganese dioxide: - d[H 2S] T/dt = k[H 2S] τ[MnO 2] . The rate constant, k, for seawater (S = 35.8, pH = 8.17) at 25°C was found to be 436 M -1 min -1, or 0.0244 m -2 1 min -1 when [MnO 2] is expressed in surface area (m 2/L). The energies of activation were found to be 14 ± 1 KJ mol -1 and 10 ± 1 KJ mol -1, respectively, for pH = 8.2 and pH = 5.0 in seawater (S = 35). The rate increased from pH 2.0 to a maximum at a pH of about 5.0 and decreased at higher pH. This pH dependence was attributed to formation of a surface complex between >MnO - and H 2S. As the concentration of HS - increases above pH = 5 the rate of the reaction decreases. The rate of sulfide oxidation by MnO 2 is not strongly dependent on ionic strength. The rates in 0.57 M NaCl were found to be slightly higher than the rates in seawater. Measurements made in solutions of the major sea salts indicated that Ca 2+ and Mg 2+ caused the rates to decrease, apparently by absorbing on the surface of manganese dioxide. Measurements made in artificial seawater (Na +, Mg 2+, Ca 2+, Cl -, and SO 2-4) were found to be in good agreement with the measurements in actual seawater. Phosphate was found to inhibit the reaction significantly.

Comparison of fusion rate and clinical results between CaO-SiO2-P2O5-B2O3 bioactive glass ceramics spacer with titanium cages in posterior lumbar interbody fusion.

PubMed

Lee, Jae Hyup; Kong, Chang-Bae; Yang, Jae Jun; Shim, Hee-Jong; Koo, Ki-Hyoung; Kim, Jeehyoung; Lee, Choon-Ki; Chang, Bong-Soon

2016-11-01

The CaO-SiO 2 -P 2 O 5 -B 2 O 3 glass ceramics spacer generates chemical bonding to adjacent bones with high mechanical stability to produce a union with the end plate, and ultimately stability. The authors aimed to compare the clinical efficacy and safety of CaO-SiO 2 -P 2 O 5 -B 2 O 3 glass ceramics with a titanium cage that is widely used for posterior lumbar interbody fusion (PLIF) surgery in the clinical field. This is a prospective, stratified randomized, multicenter, single-blinded, comparator-controlled non-inferiority trial. The present study was conducted in four hospitals and enrolled a total of 86 patients between 30 and 80 years of age who required one-level PLIF due to severe spinal stenosis, spondylolisthesis, or huge disc herniation. The Oswestry Disability Index (ODI), Short Form-36 Health Survey (SF-36), and pain visual analog scale (VAS) were assessed before surgery and at 3, 6, and 12 months after surgery. The spinal fusion rate was assessed at 6 and 12 months after surgery. The spinal fusion rate and the area of fusion, subsidence of each CaO-SiO 2 -P 2 O 5 -B 2 O 3 glass ceramics and titanium cage, and the extent of osteolysis were evaluated using a dynamic plain radiography and a three-dimensional computed tomography at 12 months after surgery. The present study was supported by BioAlpha, and some authors (JHL, C-KL, and B-SC) have stock ownership (<10,000 US dollars). From the plain radiography results, the 6-month fusion rates for the bioactive glass ceramics group and the titanium group were 89.7% and 91.4%, respectively. In addition, the 12-month fusion rates based on CT scan were 89.7% and 91.2%, respectively, showing no significant difference. However, the bone fusion area directly attached to the end plate of either bioactive glass ceramics or the titanium cage was significantly higher in the bioactive glass ceramics group than in the titanium group. The ODI, SF-36, back pain, and lower limb pain in both groups significantly improved

Oxygen Consumption Rates of Bacteria under Nutrient-Limited Conditions

PubMed Central

Riedel, Timothy E.; Nealson, Kenneth H.; Finkel, Steven E.

2013-01-01

Many environments on Earth experience nutrient limitation and as a result have nongrowing or very slowly growing bacterial populations. To better understand bacterial respiration under environmentally relevant conditions, the effect of nutrient limitation on respiration rates of heterotrophic bacteria was measured. The oxygen consumption and population density of batch cultures of Escherichia coli K-12, Shewanella oneidensis MR-1, and Marinobacter aquaeolei VT8 were tracked for up to 200 days. The oxygen consumption per CFU (QO2) declined by more than 2 orders of magnitude for all three strains as they transitioned from nutrient-abundant log-phase growth to the nutrient-limited early stationary phase. The large reduction in QO2 from growth to stationary phase suggests that nutrient availability is an important factor in considering environmental respiration rates. Following the death phase, during the long-term stationary phase (LTSP), QO2 values of the surviving population increased with time and more cells were respiring than formed colonies. Within the respiring population, a subpopulation of highly respiring cells increased in abundance with time. Apparently, as cells enter LTSP, there is a viable but not culturable population whose bulk community and per cell respiration rates are dynamic. This result has a bearing on how minimal energy requirements are met, especially in nutrient-limited environments. The minimal QO2 rates support the extension of Kleiber's law to the mass of a bacterium (100-fg range). PMID:23770901

High-rate Li-MnO2 cells for aerospace use

NASA Technical Reports Server (NTRS)

Becker-Kaiser, R.; Ruch, J.; Harms, H.-J.; Schmoede, P.; Welsh, J. R.; Vollmers, M.-J.; Pack, H.

1992-01-01

A series of comparative studies were undertaken on representative cells as objectively as possible in order to appreciate the respective advantages of the different systems. After reviewing the first test results our attention was soon focussed on the following four lithium systems: (1) Li-SOCl2; (2) Li-SO2; (3) Li-(CF(sub x))(sub n); and (4) Li-MnO2. This resulted in the decision in 1982 to adopt the Li-MnO2 system for high-rate applications.

The rate of nitrite reduction in leaves as indicated by O2 and CO2 exchange during photosynthesis

PubMed Central

Eichelmann, H.; Oja, V.; Peterson, R.B.; Laisk, A.

2011-01-01

Light response (at 300 ppm CO2 and 10–50 ppm O2 in N2) and CO2 response curves [at absorbed photon fluence rate (PAD) of 550 μmol m−2 s−1] of O2 evolution and CO2 uptake were measured in tobacco (Nicotiana tabacum L.) leaves grown on either NO3− or NH4+ as N source and in potato (Solanum tuberosum L.), sorghum (Sorghum bicolor L. Moench), and amaranth (Amaranthus cruentus L.) leaves grown on NH4NO3. Photosynthetic O2 evolution in excess of CO2 uptake was measured with a stabilized zirconia O2 electrode and an infrared CO2 analyser, respectively, and the difference assumed to represent the rate of electron flow to acceptors alternative to CO2, mainly NO2−, SO42−, and oxaloacetate. In NO3−-grown tobacco, as well as in sorghum, amaranth, and young potato, the photosynthetic O2–CO2 flux difference rapidly increased to about 1 μmol m−2 s−1 at very low PADs and the process was saturated at 50 μmol quanta m−2 s−1. At higher PADs the O2–CO2 flux difference continued to increase proportionally with the photosynthetic rate to a maximum of about 2 μmol m−2 s−1. In NH4+-grown tobacco, as well as in potato during tuber filling, the low-PAD component of surplus O2 evolution was virtually absent. The low-PAD phase was ascribed to photoreduction of NO2− which successfully competes with CO2 reduction and saturates at a rate of about 1 μmol O2 m−2 s−1 (9% of the maximum O2 evolution rate). The high-PAD component of about 1 μmol O2 m−2 s−1, superimposed on NO2− reduction, may represent oxaloacetate reduction. The roles of NO2−, oxaloacetate, and O2 reduction in the regulation of ATP/NADPH balance are discussed. PMID:21239375

Investigation of gamma ray shielding, structural and dissolution rate properties of Bi2O3-BaO-B2O3-Na2O glass system

NASA Astrophysics Data System (ADS)

Dogra, Mridula; Singh, K. J.; Kaur, Kulwinder; Anand, Vikas; Kaur, Parminder; Singh, Prabhjot; Bajwa, B. S.

2018-03-01

In the present study, quaternary system of the composition (0.45 + x) Bi2O3-(0.25 - x) BaO-0.15 B2O3-0.15 Na2O (where 0 ≤ x ≤ 0.2 mol fraction) has been prepared by using melt-quenching technique for investigation of gamma ray shielding properties. Mass attenuation coefficients and half value layer parameters have been determined experimentally at 662 keV by using 137Cs source. It has been found that experimental results of these parameters hold good agreement with theoretical values. The density, molar volume, XRD, FTIR, Raman and UV-visible studies have been used to determine structural properties of the prepared glass samples. Dissolution rate of the samples has also been measured to check their utility as long term durable glasses.

Determining oxygen consumption rate and asphyxiation point in Chanodichthys mongolicus using an improved respirometer chamber

NASA Astrophysics Data System (ADS)

Geng, Longwu; Jiang, Haifeng; Tong, Guangxiang; Xu, Wei

2017-03-01

Knowledge of oxygen consumption rates and asphyxiation points in fish is important to determine appropriate stocking and water quality management in aquaculture. The oxygen consumption rate and asphyxiation point in Chanodichthys mongolicus were detected under laboratory conditions using an improved respirometer chamber. The results revealed that more accurate estimates can be obtained by adjusting the volume of the respirometer chamber, which may avoid system errors caused by either repeatedly adjusting fish density or selecting different equipment specifications. The oxygen consumption rate and asphyxiation point of C. mongolicus increased with increasing water temperature and decreasing fish size. Changes in the C. mongolicus oxygen consumption rate were divided into three stages at water temperatures of 11-33°C: (1) a low temperature oxygen consumption rate stage when water temperature was 11-19°C, (2) the optimum temperature oxygen consumption rate stage when water temperature was 19-23°C, and (3) a high temperature oxygen consumption rate stage when water temperature was > 27°C. The temperature quotients (Q10) obtained suggested that C. mongolicus preferred a temperature range of 19-23°C. At 19°C, C. mongolicus exhibited higher oxygen consumption rates during the day when the maximum values were observed at 10:00 and 14:00 than at night when the minimum occurred at 02:00.

Low Power Consumption Gas Sensor Created from Silicon Nanowires/TiO2 Core-Shell Heterojunctions.

PubMed

Liu, Dong; Lin, Leimiao; Chen, Qiaofen; Zhou, Hongzhi; Wu, Jianmin

2017-10-27

Silicon nanowires/TiO 2 (SiNWs/TiO 2 ) array with core-shell nanostructure was created by sol-gel and drop-casting methods. The hybrid material displayed excellent sensing performance for CH 4 detection at room temperature. The chemiresistor sensor has a linear response toward CH 4 gas in the 30-120 ppm range with a detection limit of 20 ppm, which is well below most CH 4 sensors reported before. The enhanced gas sensing performance at room temperature was attributed to the creation of heterojunctions that form a depletion layer at the interface of SiNWs and TiO 2 layer. Adsorption of oxygen and corresponding gas analyte on TiO 2 layer could induce the change of depletion layer thickness and consequently the width of the SiNWs conductive channel, leading to a sensitive conductive response toward gas analyte. Compared to conventional metal oxide gas sensors, the room temperature gas sensors constructed from SiNWs/TiO 2 do not need an additional heating device and work at power at the μW level. The low power consumption feature is of great importance for sensing devices, if they are widely deployed and connected to the Internet of Things. The innovation of room temperature sensing materials may push forward the integration of gas sensing element with wireless device.

Glucose consumption rate critically depends on redox state in Corynebacterium glutamicum under oxygen deprivation.

PubMed

Tsuge, Yota; Uematsu, Kimio; Yamamoto, Shogo; Suda, Masako; Yukawa, Hideaki; Inui, Masayuki

2015-07-01

Rapid sugar consumption is important for the microbial production of chemicals and fuels. Here, we show that overexpression of the NADH dehydrogenase gene (ndh) increased glucose consumption rate in Corynebacterium glutamicum under oxygen-deprived conditions through investigating the relationship between the glucose consumption rate and intracellular NADH/NAD(+) ratio in various mutant strains. The NADH/NAD(+) ratio was strongly repressed under oxygen deprivation when glucose consumption was accelerated by the addition of pyruvate or sodium hydrogen carbonate. Overexpression of the ndh gene in the wild-type strain under oxygen deprivation decreased the NADH/NAD(+) ratio from 0.32 to 0.13, whereas the glucose consumption rate increased by 27%. Similarly, in phosphoenolpyruvate carboxylase gene (ppc)- or malate dehydrogenase gene (mdh)-deficient strains, overexpression of the ndh gene decreased the NADH/NAD(+) ratio from 1.66 to 0.37 and 2.20 to 0.57, respectively, whereas the glucose consumption rate increased by 57 and 330%, respectively. However, in a lactate dehydrogenase gene (L-ldhA)-deficient strain, although the NADH/NAD(+) ratio decreased from 5.62 to 1.13, the glucose consumption rate was not markedly altered. In a tailored D-lactate-producing strain, which lacked ppc and L-ldhA genes, but expressed D-ldhA from Lactobacillus delbrueckii, overexpression of the ndh gene decreased the NADH/NAD(+) ratio from 1.77 to 0.56, and increased the glucose consumption rate by 50%. Overall, the glucose consumption rate was found to be inversely proportional to the NADH/NAD(+) ratio in C. glutamicum cultured under oxygen deprivation. These findings could provide an option to increase the productivity of chemicals and fuels under oxygen deprivation.

Rational design of octahedron and nanowire CeO2@MnO2 core-shell heterostructures with outstanding rate capability for asymmetric supercapacitors.

PubMed

Zhu, Shi Jin; Jia, Jia Qi; Wang, Tian; Zhao, Dong; Yang, Jian; Dong, Fan; Shang, Zheng Guo; Zhang, Yu Xin

2015-10-14

Two kinds of novel CeO2@MnO2 nanostructures have been synthesized via a self-assembly strategy. The as-prepared CeO2 nanowire@MnO2 nanostructures exhibited unprecedented pseudocapacitance performance (255 F g(-1)) with outstanding rate capability. A new mechanism based on the synergistic effect between CeO2 and MnO2 was proposed to interpret this phenomenon. When assembled as an asymmetric supercapacitor, an energy density of 27.5 W h kg(-1) with a maximum power density of 1.6 kW kg(-1) was achieved for CeO2 nanowire@MnO2 nanostructures.

Food consumption and growth rates of juvenile black carp fed natural and prepared feeds

USGS Publications Warehouse

Hodgins, Nathaniel C.; Schramm, Harold L.; Gerard, Patrick D.

2014-01-01

The introduced mollusciphagic black carp Mylopharyngodon piceus poses a significant threat to native mollusks in temperate waters throughout the northern hemisphere, but consumption rates necessary to estimate the magnitude of impact on mollusks have not been established. We measured food consumption and growth rates for small (77–245 g) and large (466–1,071 g) triploid black carp held individually under laboratory conditions at 20, 25, and 30°C. Daily consumption rates (g food · g wet weight fish−1·d−1·100) of black carp that received prepared feed increased with temperature (small black carp 1.39–1.71; large black carp 1.28–2.10), but temperature-related increases in specific growth rate (100[ln(final weight) - ln(initial weight)]/number of days) only occurred for the large black carp (small black carp −0.02 to 0.19; large black carp 0.16–0.65). Neither daily consumption rates (5.90–6.28) nor specific growth rates (0.05–0.24) differed among temperatures for small black carp fed live snails. The results of these laboratory feeding trials indicate food consumption rates can vary from 289.9 to 349.5 J·g−1·d−1 for 150 g black carp receiving prepared feed, from 268.8 to 441.0 J·g−1·d−1for 800 g black carp receiving prepared feed, and from 84.8 to 90.2 J·g−1·d−1 for 150 g black carp that feed on snails. Applying estimated daily consumption rates to estimated biomass of native mollusks indicates that a relatively low biomass of bla

Structurally Engineered Nanoporous Ta2O5-x Selector-Less Memristor for High Uniformity and Low Power Consumption.

PubMed

Kwon, Soonbang; Kim, Tae-Wook; Jang, Seonghoon; Lee, Jae-Hwang; Kim, Nam Dong; Ji, Yongsung; Lee, Chul-Ho; Tour, James M; Wang, Gunuk

2017-10-04

A memristor architecture based on metal-oxide materials would have great promise in achieving exceptional energy efficiency and higher scalability in next-generation electronic memory systems. Here, we propose a facile method for fabricating selector-less memristor arrays using an engineered nanoporous Ta 2 O 5-x architecture. The device was fabricated in the form of crossbar arrays, and it functions as a switchable rectifier with a self-embedded nonlinear switching behavior and ultralow power consumption (∼2.7 × 10 -6 W), which results in effective suppression of crosstalk interference. In addition, we determined that the essential switching elements, such as the programming power, the sneak current, the nonlinearity value, and the device-to-device uniformity, could be enhanced by in-depth structural engineering of the pores in the Ta 2 O 5-x layer. Our results, on the basis of the structural engineering of metal-oxide materials, could provide an attractive approach for fabricating simple and cost-efficient memristor arrays with acceptable device uniformity and low power consumption without the need for additional addressing selectors.

Oscillation in O2 uptake in impulse exercise.

PubMed

Yano, T; Afroundeh, R; Yamanaka, R; Arimitsu, T; Lian, C S; Shirakawa, K; Yunoki, T

2014-06-01

The purpose of the present study was to examine 1) whether O(2) uptake (VO(2)) oscillates during light exercise and 2) whether the oscillation is enhanced after impulse exercise. After resting for 1 min on a bicycle seat, subjects performed 5-min pre-exercise with 25 watts work load, 10-s impulse exercise with 200 watts work load and 15-min post exercise with 25 watts work load at 80 rpm. VO(2) during pre-exercise significantly increased during impulse exercise and suddenly decreased and re-increased until 23 s after impulse exercise. In the cross correlation between heart rate (HR) and VO(2) after impulse exercise, VO(2) strongly correlated to HR with a time delay of -4 s. Peak of power spectral density (PSD) in HR appeared at 0.0039 Hz and peak of PSD in VO(2) appeared at 0.019 Hz. The peak of the cross power spectrum between VO(2) and HR appeared at 0.0078 Hz. The results suggested that there is an oscillation in O(2) uptake during light exercise that is associated with the oscillation in O(2) consumption in active muscle. The oscillation is enhanced not only by change in O(2) consumption but also by O(2) content transported from active muscle to the lungs.

Sources of variation in oxygen consumption of aquatic animals demonstrated by simulated constant oxygen consumption and respirometers of different sizes.

PubMed

Svendsen, M B S; Bushnell, P G; Christensen, E A F; Steffensen, J F

2016-01-01

As intermittent-flow respirometry has become a common method for the determination of resting metabolism or standard metabolic rate (SMR), this study investigated how much of the variability seen in the experiments was due to measurement error. Experiments simulated different constant oxygen consumption rates (M˙O2 ) of a fish, by continuously injecting anoxic water into a respirometer, altering the injection rate to correct for the washout error. The effect of respirometer-to-fish volume ratio (RFR) on SMR measurement and variability was also investigated, using the simulated constant M˙O2 and the M˙O2 of seven roach Rutilus rutilus in respirometers of two different sizes. The results show that higher RFR increases measurement variability but does not change the mean SMR established using a double Gaussian fit. Further, the study demonstrates that the variation observed when determining oxygen consumption rates of fishes in systems with reasonable RFRs mainly comes from the animal, not from the measuring equipment. © 2016 The Fisheries Society of the British Isles.

Rate constants for the quenching of metastable O2 (1Sigma g +) molecules

NASA Technical Reports Server (NTRS)

Kwang, Y. C.; Leu, M.-T.

1985-01-01

The O2 (1Sigma g +) rates for CO2, H2, N2, Cl2, CO, O3, and 2,3 DMB-2 are determined by monitoring the 762-nm emission in a fast-flow-discharge chemiluminescence detection system (Leu, 1984; Leu and Smith, 1981). The results are presented in tables and graphs and briefly characterized. The rate constants (in cu cm/s x 10 to the -16th) are 4600 + or - 500 for CO2, 7000 + or - 300 for H2, 17 + or - 1 for N2, 4.5 + or - 0.8 for Cl2, 45 + or - 5 for CO, 220,000 + or - 30,000 for O3, and 6000 + or - 100 for 2,3 DMB-2. The temperature dependence of the CO2 and O3 quenching reactions at 245-362 K is found to be negligible.

SnO2@TiO2 double-shell nanotubes for a lithium ion battery anode with excellent high rate cyclability.

PubMed

Jeun, Jeong-Hoon; Park, Kyu-Young; Kim, Dai-Hong; Kim, Won-Sik; Kim, Hong-Chan; Lee, Byoung-Sun; Kim, Honggu; Yu, Woong-Ryeol; Kang, Kisuk; Hong, Seong-Hyeon

2013-09-21

SnO2@TiO2 double-shell nanotubes have been facilely synthesized by atomic layer deposition (ALD) using electrospun PAN nanofibers as templates. The double-shell nanotubes exhibited excellent high rate cyclability for lithium ion batteries. The retention of hollow structures during cycling was demonstrated.

The gut microenvironment of sediment-dwelling Chironomus plumosus larvae as characterised with O2, pH, and redox microsensors.

PubMed

Stief, Peter; Eller, Gundula

2006-09-01

We devised a set-up in which microsensors can be used for characterising the gut microenvironment of aquatic macrofauna. In a small flow cell, we measured microscale gradients through dissected guts (O(2), pH, redox potential [E ( h )]), in the haemolymph (O(2)), and towards the body surface (O(2)) of Chironomus plumosus larvae. The gut microenvironment was compared with the chemical conditions in the lake sediment in which the animals reside and feed. When the dissected guts were incubated at the same nominal O(2) concentration as in haemolymph, the gut content was completely anoxic and had pH and E ( h ) values slightly lower than in the ambient sediment. When the dissected guts were artificially oxygenated, the volumetric O(2)-consumption rates of the gut content were at least 10x higher than in the sediment. Using these potential O(2)-consumption rates in a cylindrical diffusion-reaction model, it was predicted that diffusion of O(2) from the haemolymph to the gut could not oxygenate the gut content under in vivo conditions. Additionally, the potential O(2)-consumption rates were so high that the intake of dissolved O(2) along with feeding could be ruled out to oxygenate the gut content. We conclude that microorganisms present in the gut of C. plumosus cannot exhibit an aerobic metabolism. The presented microsensor technique and the data analysis are applicable to guts of other macrofauna species with cutaneous respiration.

Growth, oxygen consumption, and protein and RNA synthesis rates in the yolk sac larvae of the African catfish (Clarias gariepinus).

PubMed

Smith, Richard W; Ottema, Colin

2006-03-01

Rapidly growing African catfish yolk sac larvae were investigated during the first 22 h after hatching. Body compartment protein concentration increased fourfold yet oxygen consumption remained constant (mean=21.3 +/- 3.2 nmol O2 mg(-1) protein h(-1)), suggesting fast growth results mainly from yolk sac protein absorption. The protein synthesis rates at 1-2 and 5-6 h also equaled the highest conceivable rates of muscle protein synthesis; 11.6-11.9% and 7.4-7.9% day(-1), respectively. Therefore the corresponding energetic costs of protein synthesis were almost the theoretical minimum; 13.0 +/- 1.7-16.3 +/- 2.8 micromol O2 mg(-1) protein synthesised. Total protein synthesis expenditure (74.5-77.7 micromol O2 g(-1) protein h(-1)) was also less than other yolk sac larvae. These protein synthesis rates resulted from high RNA concentrations (113.2 +/- 3.4 microg RNA mg(-1) protein) and were also correlated with RNA translational efficiency. High translational efficiency (1 h; 1.2+/-0.1 mg protein synthesised microg(-1) RNA day(-1)) equaled high synthesis rate (36.8 +/- 5.4 microg RNA microg(-1) DNA day(-1)) and both declined over 22 h. This investigation suggests rapid growth combines growth efficiency and compensatory energy partitioning. This accommodates the ontogenetic and phylogenetic standpoints imposed by energy budget limitations.

Oxygen consumption by mitochondria from an endotherm and an ectotherm.

PubMed

Berner, N J

1999-09-01

Comparisons of metabolic properties of mitochondria from an endothermic and an ectothermic vertebrate were performed. Oxygen (O2) consumption rates of liver mitochondria from laboratory mice and western fence lizard (Sceloporus occidentalis) were determined over a range of temperatures (10, 20, 30 and 37 degrees C) and in the presence of a variety of substrates. At 37 degrees C the O2 consumption rate of mouse mitochondria was 4-11 times higher than lizard mitochondria in the presence of five of eight substrates. This range of differences is similar to differences reported for O2 consumption of endothermic animals, tissues and cells over those of ectotherms. Thermal sensitivity of mitochondria was measured by calculation of Q10s for O2 consumption. Q10s were highest for mouse mitochondria overall. The range that showed the highest Q10s for the mouse mitochondria was 30-20 degrees C, whereas for the lizard mitochondria it was 20-10 degrees C. Thus, mitochondria from the ectotherm showed a lower degree of temperature sensitivity than did mitochondria from the endotherm. The preferred substrate for all mitochondria at all temperatures was succinate, but mouse mitochondria then showed some preference for alpha-ketoglutarate and citrate, whereas lizard mitochondria showed a preference for pyruvate and malate + pyruvate.

Hemoglobin-based O2 carrier O2 affinity and capillary inlet pO2 are important factors that influence O2 transport in a capillary.

PubMed

Dimino, Michael L; Palmer, Andre F

2007-01-01

Hemopure (Biopure; Cambridge, MA) and PolyHeme (Northfield Laboratories; Evanston, IL) are two acellular hemoglobin-based O2 carriers (HBOCs) currently in phase III clinical trials for use as red blood cell substitutes. The most common adverse side effect that these HBOCs exhibit is increased vasoconstriction. Autoregulatory theory has been presented as a possible explanation for this physiological effect, where it is hypothesized that low-affinity HBOCs over-deliver O2 to tissues surrounding arterioles, thereby eliciting vasoconstriction. In this paper, we wanted to investigate HBOC oxygenation of tissue surrounding a capillary, which is the smallest element of the circulatory system. An a priori model has been developed in which the performance of mixtures of acellular HBOCs (synthesized by our group and others) and human red blood cells (hRBCs) has been simulated using a Krogh tissue cylinder model (KTCM) comprising a capillary surrounded by a capillary membrane and skeletal muscle tissue in cylindrical coordinates with specified tissue O2 consumption rates and Michaelis-Menten kinetics. In this study, the total hemoglobin (hRBCs and HBOCs) concentration was kept constant. The HBOCs studied possessed O2 affinities that were higher and lower compared to hRBCs (P50's spanned 5-55 mmHg), and the equilibrium binding/release of oxygen to/from the HBOCs was modeled using the Adair equation. At normoxic inlet pO2's, there was no correlation between O2 flux out of the capillary and the O2 affinity of the HBOC. However, a correlation was found between the average pO2 tension in the capillary and the O2 affinity of the HBOC. Additionally, we studied the change in the O2 equilibrium curve of HBOCs with different O2 affinities over a wide range of inlet pO2's and found that changing the inlet pO2 greatly affected which HBOC, having a unique O2 affinity, best delivered O2 to the surrounding tissue. The analysis of oxygen transport presented could lead to a better prediction

Zero-Power-Consumption Solar-Blind Photodetector Based on β-Ga2O3/NSTO Heterojunction.

PubMed

Guo, Daoyou; Liu, Han; Li, Peigang; Wu, Zhenping; Wang, Shunli; Cui, Can; Li, Chaorong; Tang, Weihua

2017-01-18

A solar-blind photodetector based on β-Ga 2 O 3 /NSTO (NSTO = Nb:SrTiO 3 ) heterojunctions were fabricated for the first time, and its photoelectric properties were investigated. The device presents a typical positive rectification in the dark, while under 254 nm UV light illumination, it shows a negative rectification, which might be caused by the generation of photoinduced electron-hole pairs in the β-Ga 2 O 3 film layer. With zero bias, that is, zero power consumption, the photodetector shows a fast photoresponse time (decay time τ d = 0.07 s) and the ratio I photo /I dark ≈ 20 under 254 nm light illumination with a light intensity of 45 μW/cm 2 . Such behaviors are attributed to the separation of photogenerated electron-hole pairs driven by the built-in electric field in the depletion region of β-Ga 2 O 3 and the NSTO interface, and the subsequent transport toward corresponding electrodes. The photocurrent increases linearly with increasing the light intensity and applied bias, while the response time decreases with the increase of the light intensity. Under -10 V bias and 45 μW/cm 2 of 254 nm light illumination, the photodetector exhibits a responsivity R λ of 43.31 A/W and an external quantum efficiency of 2.1 × 10 4 %. The photo-to-electric conversion mechanism in the β-Ga 2 O 3 /NSTO heterojunction photodetector is explained in detail by energy band diagrams. The results strongly suggest that a photodetector based on β-Ga 2 O 3 thin-film heterojunction structure can be practically used to detect weak solar-blind signals because of its high photoconductive gain.

The relationship between body temperature, heart rate, breathing rate, and rate of oxygen consumption, in the tegu lizard (Tupinambis merianae) at various levels of activity.

PubMed

Piercy, Joanna; Rogers, Kip; Reichert, Michelle; Andrade, Denis V; Abe, Augusto S; Tattersall, Glenn J; Milsom, William K

2015-12-01

The present study determined whether EEG and/or EMG recordings could be used to reliably define activity states in the Brazilian black and white tegu lizard (Tupinambis merianae) and then examined the interactive effects of temperature and activity states on strategies for matching O2 supply and demand. In a first series of experiments, the rate of oxygen consumption (VO2), breathing frequency (fR), heart rate (fH), and EEG and EMG (neck muscle) activity were measured in different sleep/wake states (sleeping, awake but quiet, alert, or moving). In general, metabolic and cardio-respiratory changes were better indictors of the transition from sleep to wake than were changes in the EEG and EMG. In a second series of experiments, the interactive effects of temperature (17, 27 and 37 °C) and activity states on fR, tidal volume (VT), the fraction of oxygen extracted from the lung per breath (FIO2-FEO2), fH, and the cardiac O2 pulse were quantified to determine the relative roles of each of these variables in accommodating changes in VO2. The increases in oxygen supply to meet temperature- and activity-induced increases in oxygen demand were produced almost exclusively by increases in fH and fR. Regression analysis showed that the effects of temperature and activity state on the relationships between fH, fR and VO2 was to extend a common relationship along a single curve, rather than separate relationships for each metabolic state. For these lizards, the predictive powers of fR and fH were maximized when the effects of changes in temperature, digestive state and activity were pooled. However, the best r(2) values obtained were 0.63 and 0.74 using fR and fH as predictors of metabolic rate, respectively.

Photolysis of H2O-H2O2 Mixtures: The Destruction of H2O2

NASA Technical Reports Server (NTRS)

Loeffler, M. J.; Fama, M.; Baragiola, R. A.; Carlson, R. W.

2013-01-01

We present laboratory results on the loss of H2O2 in solid H2O + H2O2 mixtures at temperatures between 21 and 145 K initiated by UV photolysis (193 nm). Using infrared spectroscopy and microbalance gravimetry, we measured the decrease of the 3.5 micrometer infrared absorption band during UV irradiation and obtained a photodestruction cross section that varies with temperature, being lowest at 70 K. We use our results, along with our previously measured H2O2 production rates via ionizing radiation and ion energy fluxes from the spacecraft to compare H2O2 creation and destruction at icy satellites by ions from their planetary magnetosphere and from solar UV photons. We conclude that, in many cases, H2O2 is not observed on icy satellite surfaces because the H2O2 photodestruction rate is much higher than the production rate via energetic particles, effectively keeping the H2O2 infrared signature at or below the noise level.

Regional cell density distribution and oxygen consumption rates in porcine TMJ discs: an explant study.

PubMed

Kuo, J; Shi, C; Cisewski, S; Zhang, L; Kern, M J; Yao, H

2011-07-01

To determine the regional cell density distribution and basal oxygen consumption rates (based on tissue volume and cell number) of temporomandibular joint (TMJ) discs and further examine the impact of oxygen tension on these rates. TMJ discs from pigs aged 6-8 months were divided into five regions: anterior, intermediate, posterior, lateral and medial. The cell density was determined using confocal laser scanning microscopy. The change in oxygen tension was recorded while TMJ disc explants were cultured in sealed metabolism chambers. The volume based oxygen consumption rate of explants was determined by theoretical curve-fitting of the recorded oxygen tension data with the Michaelis-Menten equation. The rate on a per-cell basis was calculated based on the cell density measurements and volume based rate measured in another group of discs. The overall cell density [mean, 95% confidence interval (CI)] was 51.3 (21.3-81.3) × 10(6) cells/mL wet tissue. Along the anteroposterior axis, the anterior band had 25.5% higher cell density than the intermediate zone (P<0.02) and 29.1% higher than the posterior band (P<0.008). Along the mediolateral axes, the medial region had 26.2% higher cell density than the intermediate zone (P<0.04) and 25.4% higher than the lateral region (P<0.045). The overall volume and cell based maximum oxygen consumption rates were 1.44 (0.44-2.44) μmol/mL wet tissue/h and 28.7 (12.2-45.2)nmol/10(6)cells/h, respectively. The central regions (intermediate, lateral, and medial) had significantly higher volume based (P<0.02) and cell based (P<0.005) oxygen consumption rates than the anterior and posterior bands. At high oxygen tension, the oxygen consumption rate remained constant, but dropped as oxygen tension fell below 5%. The TMJ disc had higher cell density and oxygen consumption rates than articular cartilage reported in the literature. These results suggest that a steeper oxygen gradient may exist in the TMJ disc and may be vulnerable to

Regional Cell Density Distribution and Oxygen Consumption Rates in Porcine TMJ Discs: An Explant Study

PubMed Central

Kuo, Jonathan; Shi, Changcheng; Cisewski, Sarah; Zhang, Lixia; Kern, Michael J.; Yao, Hai

2011-01-01

Objective To determine the regional cell density distribution and basal oxygen consumption rates (based on tissue volume and cell number) of temporomandibular joint (TMJ) discs and further examine the impact of oxygen tension on these rates. Design TMJ discs from pigs aged 6–8 months were divided into five regions: anterior, intermediate, posterior, lateral and medial. The cell density was determined using confocal laser scanning microscopy. The change in oxygen tension was recorded while TMJ disc explants were cultured in sealed metabolism chambers. The volume based oxygen consumption rate of explants was determined by theoretical curve fitting of the recoded oxygen tension data with the Michaelis-Menten equation. The rate on a per-cell basis was calculated based on the cell density measurements and volume based rate measured in another group of discs. Results The overall cell density (mean, 95% CI) was 51.3(21.3–81.3)×106cells/mL wet tissue. Along the anteroposterior axis, the anterior band had 25.5% higher cell density than the intermediate zone (p<0.02) and 29.1% higher than the posterior band (p<0.008). Along the mediolateral axes, the medial region had 26.2% higher cell density than the intermediate zone (p<0.04) and 25.4% higher than the lateral region (p<0.045). The overall volume and cell based maximum oxygen consumption rates were 1.44(0.44–2.44) μmol/mL wet tissue/hr and 28.7(12.2–45.2) nmol/106 cells/hr, respectively. The central regions (intermediate, lateral, and medial) had significantly higher volume based (p<0.02) and cell based (p<0.005) oxygen consumption rates than the anterior and posterior bands. At high oxygen tension, the oxygen consumption rate remained constant, but dropped as oxygen tension fell below 5%. Conclusions The TMJ disc had higher cell density and oxygen consumption rates than articular cartilage reported in the literature. These results suggest that a steeper oxygen gradient may exist in the TMJ disc and may be

Atomic Layer Deposition of Al2O3-Ga2O3 Alloy Coatings for Li[Ni0.5Mn0.3Co0.2]O2 Cathode to Improve Rate Performance in Li-Ion Battery.

PubMed

Laskar, Masihhur R; Jackson, David H K; Guan, Yingxin; Xu, Shenzhen; Fang, Shuyu; Dreibelbis, Mark; Mahanthappa, Mahesh K; Morgan, Dane; Hamers, Robert J; Kuech, Thomas F

2016-04-27

Metal oxide coatings can improve the electrochemical stability of cathodes and hence, their cycle-life in rechargeable batteries. However, such coatings often impose an additional electrical and ionic transport resistance to cathode surfaces leading to poor charge-discharge capacity at high C-rates. Here, a mixed oxide (Al2O3)1-x(Ga2O3)x alloy coating, prepared via atomic layer deposition (ALD), on Li[Ni0.5Mn0.3Co0.2]O2 (NMC) cathodes is developed that has increased electron conductivity and demonstrated an improved rate performance in comparison to uncoated NMC. A "co-pulsing" ALD technique was used which allows intimate and controlled ternary mixing of deposited film to obtain nanometer-thick mixed oxide coatings. Co-pulsing allows for independent control over film composition and thickness in contrast to separate sequential pulsing of the metal sources. (Al2O3)1-x(Ga2O3)x alloy coatings were demonstrated to improve the cycle life of the battery. Cycle tests show that increasing Al-content in alloy coatings increases capacity retention; whereas a mixture of compositions near (Al2O3)0.5(Ga2O3)0.5 was found to produce the optimal rate performance.

Angiotensin II inhibits ADH-stimulated cAMP: role on O2- and transport-related oxygen consumption in the loop of Henle.

PubMed

Silva, G B; Juncos, L I; Baigorria, S T; Garcia, N H

2013-01-01

Dehydration and acute reductions of blood pressure increases ADH and Ang II levels. These hormones increase transport along the distal nephron. In the thick ascending limb (TAL) ADH increases transport via cAMP, while Ang II acts via superoxide (O2-). However, the mechanism of interaction of these hormones in this segment remains unclear. The aim of this study was to explore ADH/Ang II interactions on TAL transport. For this, we measured the effects of ADH/Ang II, added sequentially to TAL suspensions from Wistar rats, on oxygen consumption (QO2) -as a transport index-, cAMP and O2-. Basal QO2 was 112+-5 nmol O2/min/mg protein. Addition of ADH (1nM) increased QO2 by 227 percent. In the presence of ADH, Ang II (1nM) elicited a QO2 transient response. During an initial 3.1+-0.7 minutes after adding Ang II, QO2 decreased 58 percent (p less than 0.03 initial vs. ADH) and then rose by 188 percent (p less than 0.03 late vs initial Ang II). We found that Losartan blocked the initial effects of Ang II and the latter blocked ADH and forskolin-stimulated cAMP. The NOS inhibitor L-NAME or the AT2 receptor antagonist PD123319 showed no effect on transported related oxygen consumption. Then, we assessed the late period after adding Ang II. The O2- scavenger tempol blocked the late Ang II effects on QO2, while Ang II increased O2- production during this period. We conclude that 1) Ang II has a transient effect on ADH-stimulated transport; 2) this effect is mediated by AT1 receptors; 3) the initial period is mediated by decreased cAMP and 4) the late period is mediated by O2-.

Rate Coefficient for Collisional Removal of O2(X3Σ ^-g, v = 1) with O Atoms at 240 K

NASA Astrophysics Data System (ADS)

Pejaković, D. A.; Campbell, Z.; Kalogerakis, K. S.; Copeland, R. A.; Slanger, T. G.

2004-12-01

Knowledge of the water concentration profile is key to understanding of the chemistry and energy flow in the stratosphere and mesosphere. One of the tasks of the SABER instrument in NASA's TIMED mission is to measure water vapor concentration by detecting H2O(ν 2) emission in the 6.8 μ m region. An important source of the H2O(ν 2) emission is the collisional deactivation of vibrationally excited O2: O2(X3Σ ^-g, v = 1) + H2O <-> O2(X3Σ ^-g, v = 0) + H2O(ν 2). For reliable interpretation of the SABER data it is crucial to determine rate coefficient for the competing process: O2(X3Σ ^-g, v = 1) + O(3P) -> O2(X3Σ ^-g, v = 0) + O(3P) [1]. Laboratory measurements are reported of the rate coefficient for collisional removal of O2(X3Σ ^-g, v = 1) by O(3P) at a temperature of 240 K, relevant to the upper mesosphere. Instead of directly detecting the O2(X3Σ ^-g, v = 1) population, a novel, technically simpler, approach is used in which the v = 1 level of the O2(a1Δ g) state is monitored. With ground-state O2 present, owing to the rapid equilibration of the O2(X3Σ ^-g, v = 1) and O2(a1Δ g, v = 1) populations via the processes O2(a1Δ g, v = 1) + O2(X3Σ ^-g, v = 0) <-> O2(a1Δ g, v = 0) + O2(X3Σ ^-g, v = 1), the information on the O2(X3Σ ^-g, v = 1) kinetics is extracted from the O2(a1Δ g, v = 1) temporal evolution. A two-laser method is employed, in which the pulsed output of the first laser near 285 nm photodissociates ozone to produce atomic oxygen and O2(a1Δ g, v = 1), and the pulsed output of the second laser detects O2(a1Δ g, v = 1) via the resonance-enhanced multiphoton ionization. In the same experiment, rate coefficients for removal of O2(a1Δ g, v = 1) with the atmospherically relevant colliders O2, CO2, and O also were measured at room temperature and 240 K. The measured rate coefficient for O2(X3Σ ^-g, v = 1) removal by O(3P) is in the range 2--3 × 10-12 cm3s-1 at 240 K, compared to the recently measured room temperature value of about 3 × 10

MRI quantification of human fetal O2 delivery rate in the second and third trimesters of pregnancy.

PubMed

Rodríguez-Soto, Ana E; Langham, Michael C; Abdulmalik, Osheiza; Englund, Erin K; Schwartz, Nadav; Wehrli, Felix W

2018-01-22

The purpose of this study was to estimate fetal O 2 delivery rate in vivo across a range of gestational ages. Toward this, a calibration equation for T 2 -based oximetry was derived. Umbilical cord blood of varying hematocrit (Hct) and oxygen saturation (HbO 2 ) levels was prepared and T 2 measured using a T 2 -prepared balanced steady-state free-precession sequence at 1.5 T. The relationship between blood R 2  = 1/T 2 , HbO 2 and Hct was established based on the model R2=(1-Hct)R2,plasma+Hct R2,RBC+k·Hct·(1-Hct)·(1-HbO2)2. Experimental R 2 , HbO 2 , and Hct levels were fit to the model-yielding values of k, R2,plasma, and R2,RBC (R 2 of plasma and erythrocytes). Umbilical vein T 2 measured in vivo was then converted to HbO 2 , yielding-together with blood flow rate-the fetal O 2 delivery rate in 22 pregnancies (gestational age 30 ± 3 weeks). Constants derived from the fit (R 2  = 0.94) were k = 83.1 s -1 , R2,plasma=1.1  s-1, and R2,RBC=12.9  s-1. The R2,RBC and k were found to be larger than those obtained for adult blood, likely the result of differences in dominant hemoglobin type. Data suggest that the use of adult blood calibration could entail errors up 10% in fetal blood HbO 2 . The average umbilical vein blood flow rate (89.5 ± 17.2 mL/min/kg), HbO 2 (84 ± 7%,), and fetal O 2 delivery rate (15.1 ± 3.8 mL O 2 /min/kg) were independent of gestational age. The fetal O 2 delivery rate agreed well with the results obtained with invasive methods at term. The present work describes strategies for measuring umbilical vein blood flow rate and HbO 2 in vivo and estimates fetal O 2 delivery rate noninvasively with quantitative MRI during the second and third trimesters of pregnancy. Magn Reson Med, 2018. © 2018 International Society for Magnetic Resonance in Medicine. © 2018 International Society for Magnetic Resonance in Medicine.

Commercial fertilizers: Total US fertilizer consumption 44.9 million tons in 1989

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

Hargett, N.L.; Berry, J.T.; McKinney, S.L.

1989-12-31

US fertilizer consumption for the 1988--1989 year was 44.9 million tons of material-an increase of less than one percent from the previous year. The average plant nutrient content of all fertilizers decreased slightly as total plant nutrient consumption declined from 19.61 million to 19.59 million tons of N, P{sub 2}O{sub 5}, and K{sub 2}O. Total nitrogen consumption increased one percent to 10.63 million tons, while P{sub 2}O{sub 5} use decreased by less than one percent to 4.12 million tons. Potash consumption declined from 4.97 million tons to 4.83 million tons K{sub 2}O-a 2.8 percent decrease. Consumption patterns varied widely frommore » state to state as weather conditions adversely affected fertilizer application even with significant increases in total planted crop acreage. Illinois, Indiana, Iowa, Minnesota, and Ohio reported a decline in total plant nutrient application while several of the southeastern states registered an increase in consumption. Nutrient levels in mixed fertilizers remained unchanged as slight gains in the nitrogen and P{sub 2}O{sub 5} content were offset by a decline in K{sub 2}O. Consumption of ammonium polyphosphate solution (10-34-0) and monoammonium phosphates increased 9.2 percent and 12.8 percent respectively, while diammonium phosphate (18-46-0) use was 2.4 percent below last year. A general increase in the use of nitrogen materials was reported with the exception of nitrogen solutions which declined 2.1 percent from 1987--1988. Urea consumption rose almost 2 percent. ammonium nitrate was up 8.1 percent, and ammonium sulfate recorded a 9.5 percent gain in consumption. Anhydrous ammonia use was only 35,000 tons above last year. This document contains a state by state listing of individual fertilizer consumption rates, numerical data only.« less

Commercial fertilizers: Total US fertilizer consumption 44. 9 million tons in 1989

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

Hargett, N.L.; Berry, J.T.; McKinney, S.L.

1989-01-01

US fertilizer consumption for the 1988--1989 year was 44.9 million tons of material-an increase of less than one percent from the previous year. The average plant nutrient content of all fertilizers decreased slightly as total plant nutrient consumption declined from 19.61 million to 19.59 million tons of N, P[sub 2]O[sub 5], and K[sub 2]O. Total nitrogen consumption increased one percent to 10.63 million tons, while P[sub 2]O[sub 5] use decreased by less than one percent to 4.12 million tons. Potash consumption declined from 4.97 million tons to 4.83 million tons K[sub 2]O-a 2.8 percent decrease. Consumption patterns varied widely frommore » state to state as weather conditions adversely affected fertilizer application even with significant increases in total planted crop acreage. Illinois, Indiana, Iowa, Minnesota, and Ohio reported a decline in total plant nutrient application while several of the southeastern states registered an increase in consumption. Nutrient levels in mixed fertilizers remained unchanged as slight gains in the nitrogen and P[sub 2]O[sub 5] content were offset by a decline in K[sub 2]O. Consumption of ammonium polyphosphate solution (10-34-0) and monoammonium phosphates increased 9.2 percent and 12.8 percent respectively, while diammonium phosphate (18-46-0) use was 2.4 percent below last year. A general increase in the use of nitrogen materials was reported with the exception of nitrogen solutions which declined 2.1 percent from 1987--1988. Urea consumption rose almost 2 percent. ammonium nitrate was up 8.1 percent, and ammonium sulfate recorded a 9.5 percent gain in consumption. Anhydrous ammonia use was only 35,000 tons above last year. This document contains a state by state listing of individual fertilizer consumption rates, numerical data only.« less

High rate performance supercapacitor based on Nb2O5 nanoparticles

NASA Astrophysics Data System (ADS)

Ahmed, Sultan; Ahmed, Ahsan; Rafat, M.

2018-05-01

In the present communication, we report the successful preparation of Nb2O5 nanoparticles from precursor NbCl5 using hydrothermal method, followed by thermal annealing. The surface morphology of the as-prepared material was studied using scanning electron microscopy (SEM) while crystal structure and vibrational response was characterized using X-ray diffraction (XRD) and Raman spectroscopy. The observed results indicate the successful synthesis of Nb2O5 nanoparticles. The electrochemical properties of the material was investigated in two-electrode assembly in 1 M LiClO4 solution using the techniques of electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Both EIS and CV studies show high rate performance of the assembled supercapacitor cells. Fabricated cell offers low response time (˜17.1 ms), and the shape of CV pattern remains almost rectangular, even for high scan rates (˜20 V s-1).

Optimal temperature for whole-body hypothermia in the newborn: an in vitro study using foreskin mitochondrial oxygen consumption.

PubMed

Al Zaabi, A; Rahmani, A Y; Souid, A

2014-01-01

Whole-body hypothermia (to 33.5 ± 0.5°C) is a therapeutic modality that reduces risks of death and neurodevelopmental disability in neonates subjected to hypoxic-ischemic insults. This in vitro study was designed to determine changes in neonatal cellular metabolism with temperature. Its main aim was to compare the metabolic rate at ≤33°C with that at ≥35°C. Foreskin specimens were used as a source of neonatal tissue. Cellular respiration (mitochondrial O2 consumption) was used as a surrogate biomarker for the metabolic rate. Foreskin specimens from healthy newborns were collected immediately after circumcision and processed within one hour for measuring the rate of O2 consumption at various temperatures (±0.5°C). O2 consumption was determined as function of time from the phosphorescence decay of Pd (II) meso-tetra-(4-sulfonatophenyl)-tetrabenzoporphyrin. In a vial sealed from air and containing foreskin specimen in phosphate-buffered saline supplemented with 5 mM glucose, [O2] decreased linearly with time, confirming its zero-order kinetics. The rate of O2 consumption (μM O2.min-1), thus, was the negative of the slope of [O2] vs. time. Cyanide inhibited O2 consumption, confirming the oxidation occurred in the respiratory chain. Cellular respiration at ≤33°C (n = 25) significantly differed from that at ≥35°C (n = 24), p < 0.001. The rate (μM O2.min-1.mg-1) at 25°C was 0.034 ± 0.006 (n = 11, p = 0.044), at 33°C was 0.029 ± 0.008 (n = 14, reference temperature), at 35°C was 0.062 ± 0.020 (2-fold higher, n = 18, p < 0.001), and at 37°C was 0.061 ± 0.009 (2-fold higher, n = 6, p < 0.001). Neonatal foreskin cellular respiration is highly sensitive to critical temperatures (33°C vs. 35°C).

Quantifying intracellular rates of glycolytic and oxidative ATP production and consumption using extracellular flux measurements

PubMed Central

Mookerjee, Shona A.; Gerencser, Akos A.; Nicholls, David G.; Brand, Martin D.

2017-01-01

Partitioning of ATP generation between glycolysis and oxidative phosphorylation is central to cellular bioenergetics but cumbersome to measure. We describe here how rates of ATP generation by each pathway can be calculated from simultaneous measurements of extracellular acidification and oxygen consumption. We update theoretical maximum ATP yields by mitochondria and cells catabolizing different substrates. Mitochondrial P/O ratios (mol of ATP generated per mol of [O] consumed) are 2.73 for oxidation of pyruvate plus malate and 1.64 for oxidation of succinate. Complete oxidation of glucose by cells yields up to 33.45 ATP/glucose with a maximum P/O of 2.79. We introduce novel indices to quantify bioenergetic phenotypes. The glycolytic index reports the proportion of ATP production from glycolysis and identifies cells as primarily glycolytic (glycolytic index > 50%) or primarily oxidative. The Warburg effect is a chronic increase in glycolytic index, quantified by the Warburg index. Additional indices quantify the acute flexibility of ATP supply. The Crabtree index and Pasteur index quantify the responses of oxidative and glycolytic ATP production to alterations in glycolysis and oxidative reactions, respectively; the supply flexibility index quantifies overall flexibility of ATP supply; and the bioenergetic capacity quantifies the maximum rate of total ATP production. We illustrate the determination of these indices using C2C12 myoblasts. Measurement of ATP use revealed no significant preference for glycolytic or oxidative ATP by specific ATP consumers. Overall, we demonstrate how extracellular fluxes quantitatively reflect intracellular ATP turnover and cellular bioenergetics. We provide a simple spreadsheet to calculate glycolytic and oxidative ATP production rates from raw extracellular acidification and respiration data. PMID:28270511

Something from nothing: Estimating consumption rates using propensity scores, with application to emissions reduction policies

PubMed Central

Büchs, Milena; Schnepf, Sylke V.

2017-01-01

Consumption surveys often record zero purchases of a good because of a short observation window. Measures of distribution are then precluded and only mean consumption rates can be inferred. We show that Propensity Score Matching can be applied to recover the distribution of consumption rates. We demonstrate the method using the UK National Travel Survey, in which c.40% of motorist households purchase no fuel. Estimated consumption rates are plausible judging by households’ annual mileages, and highly skewed. We apply the same approach to estimate CO2 emissions and outcomes of a carbon cap or tax. Reliance on means apparently distorts analysis of such policies because of skewness of the underlying distributions. The regressiveness of a simple tax or cap is overstated, and redistributive features of a revenue-neutral policy are understated. PMID:29020029

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.

[Degradation of Organic Sunscreens 2-hydroxy-4-methoxybenzophenone by UV/ H2O2 Process: Kinetics and Factors].

PubMed

Feng, Xin-xin; Du, Er-deng; Guo, Ying-qing; Li, Hua-jie; Liu, Xiang; Zhou, Fang

2015-06-01

Organic sunscreens continue to enter the environment through people's daily consumption, and become a kind of emerging contaminants. The photochemical degradation of benzophenone-3 (BP-3) in water by UV/H2O2 process was investigated. Several factors, including the initial BP-3 concentration, H2O2 concentration, UV light intensity, coexisting cations and anions, humic acid and tert-butyl alcohol, were also discussed. The results showed that BP-3 degradation rate constant decreased with increasing initial BP-3 concentration, while increased with increasing H2O2 dosage and UV intensity. Coexisting anions could reduce the degradation rate, while coexisting ferric ions could stimulate the production of OH through Fenton-like reaction, further significantly accelerated BP-3 degradation process. The BP-3 degradation would be inhibited by humic acid or tert-butyl alcohol. The electrical energy per order (E(Eo)) values were also calculated to evaluate the cost of BP-3 degradation by UV/H2O2 process. The addition of ferric ions significantly reduced the value of E(Eo). The investigation of processing parameter could provide a reference for the practical engineering applications of benzophenone compounds removal by UV/H2O2 process.

Effect of Na poisoning catalyst (V2O5-WO3/TiO2) on denitration process and SO3 formation

NASA Astrophysics Data System (ADS)

Xiao, Haiping; Chen, Yu; Qi, Cong; Ru, Yu

2018-03-01

This paper aims to study the effect of alkali metal sodium (Na) poisoning on the performance of the Selective Catalytic Reduction (SCR) catalyst. The result showed that Na2SO4 poisoning leads to a reduced denitration rate of the SCR catalyst and an increase in the SO3 generation rate. Na2O poisoning leads to a significant reduction in the denitration rate of the SCR catalyst and marginally improves the formation of SO3. The maximum of the SO3 generation rate for a Na2SO4-poisoned catalyst reached 1.35%, whereas it was only 0.85% for the SCR catalyst. When the SO2 was contained in flue gas, the denitration rate for the Na2O-poisoned catalyst clearly increased by more than 28%. However, the effect of SO2 on the Na2SO4-poisoned catalyst was very slight. The denitration rate of the SCR catalyst decreased with an increase in the Na content. The BET and XRD results showed that Na poisoning of the catalyst decreased the number of acid sites, the reducibility of the catalyst, the surface area, and pore volume. The H2-TPR and NH3-TPD results show that Na decreases the number of acid sites and the reducibility of the catalyst. The FT-IR and XPS results showed that Na2O poisoning led to the decrease of V5+dbnd O bonds and the consumptions of oxygen atoms. Na2SO4 poisoning can improve surface adsorbed oxygen, which was beneficial for the SO2-SO3 conversion reaction.

Estimation of oxygen consumption during cycling and rowing.

PubMed

Baig, Dur-e-Zehra; Savkin, Andrey V; Celler, Branko G

2012-01-01

The aim of this paper is to develop estimator that can predict oxygen consumption (V(O2)) during cycling and rowing exercises, by using non-invasive and easily measurable quantities such as heart rate (HR), respiratory rate (RespR) and frequency of exercising activity. The frequency of exercise is quantified as a universal measure of exercise intensity and is known as Exercise Rate (ER). This ER is responsible for deviation in V(O2) (ΔV(O2)), HR (ΔHR), and RespR (ΔRespR) from their respective baseline measurements during exercise. Therefore, ΔV(O2) can be estimated from Δ, ΔRespR and ER. The resting measured of V(O2) is referred as V(O(2rest)); this is computed from the physical fitness of an individual. The Hammerstein model is adopted for the estimation of ΔV(O2). Results in this study demonstrate that the developed estimators for each type of exercise are capable of estimating V(O2) by adding up V(O(2rest)) and ΔV(O2) at various intensities during cycling and rowing.

Controls on the Stability of Atmospheric O2 over Geologic Time Scales (Invited)

NASA Astrophysics Data System (ADS)

Rothman, D.; Bosak, T.

2013-12-01

The concentration of free oxygen in Earth's surface environment represents a balance between the accumulation of O2, due to long-term burial of organic carbon in sediments, and the consumption of O2 by weathering processes and the oxidation of reduced gases. The stability of modern O2 levels is typically attributed to a negative feedback that emerges when the production and consumption fluxes are expressed as a function of O2 concentration. Empirical studies of modern burial of organic carbon suggest that the production of O2 is a logarithmically decreasing function of the duration of time---the "oxygen exposure time (OET)"--over which sedimentary organic carbon is exposed to O2. The OET hypothesis implies that a fraction of organic matter is physically protected from anaerobic decay by its association with clay-sized mineral surface area, but susceptible to aerobic decay, either oxidatively or via free extracellular hydrolytic enzymes. By assuming that the long-term aerobic degradation is diffusion-limited, we predict the logarithmic decay of the OET curve. We note, however, that exposure to O2 may enhance not only degradation but also physical protection due to the precipitation of iron oxides and clay minerals. When the rate of transformation from the unprotected state to the protected state exceeds a small fraction of the average oxidative degradation rate, our theoretical OET curve develops a maximum at small O2 exposure times. In this case, the equilibrium O2 concentration can lose its stability. These observations may help explain major fluctuations in Earth's carbon cycle and the rise of O2 during the Proterozoic (2000--542 Ma).

Crystal Phases Formed in a CaO-Fe2O3 System Under a High Cooling Rate in Air

NASA Astrophysics Data System (ADS)

Kashiwaya, Yoshiaki

2017-12-01

A CaO-Fe2O3 system is a fundamental binary system for the iron ore sintering process. Although the basic reactions have been investigated since the 1960s, melting and solidification caused by the combustion of coke results in an unstable state owing to extreme temperature variations. In this study, using a hot thermocouple method, samples of 10 pct CaO-90 pct Fe2O3 and 20 pct CaO-80 pct Fe2O3 were melted on a thermocouple and quenched with several techniques. The obtained samples were precisely examined by XRD. It was found that the sample containing 10 pct CaO-90 pct Fe2O3 changed to 10 pct CaO-13 pct FeO-77 pct Fe2O3 under an oxygen partial pressure ( P_{{{O}2 }} ) of 0.21 during melting. For the 10 pct CaO sample, the crystal phases found at a low cooling rate (509 K/s) were WFss, C4WF8 (C: CaO, W: FeO, F: Fe2O3), and C2W4F9. When the sample composition was 20 pct CaO, the precipitated crystal phases were C4WF4, C4F7, and C4WF8. On the other hand, the crystal phases for high cooling rates (1590 and 7900 K/s) with 10 pct CaO were WFss (solid solution of WF and F), F, and C2W4F9. The formation of the equilibrium phases WFss, F, C4WF4, and C4WF8 can be understood by examining the isothermal section of the phase diagrams, while the unstable phases C2W4F9 and C4F7 are discussed on the basis of the reactions under an equilibrium state.

Mechanisms for chemostatic behavior in catchments: implications for CO2 consumption by mineral weathering

USGS Publications Warehouse

Clow, David W.; Mast, M. Alisa

2010-01-01

Concentrations of weathering products in streams often show relatively little variation compared to changes in discharge, both at event and annual scales. In this study, several hypothesized mechanisms for this “chemostatic behavior” were evaluated, and the potential for those mechanisms to influence relations between climate, weathering fluxes, and CO2 consumption via mineral weathering was assessed. Data from Loch Vale, an alpine catchment in the Colorado Rocky Mountains, indicates that cation exchange and seasonal precipitation and dissolution of amorphous or poorly crystalline aluminosilicates are important processes that help regulate solute concentrations in the stream; however, those processes have no direct effect on CO2 consumption in catchments. Hydrograph separation analyses indicate that old water stored in the subsurface over the winter accounts for about one-quarter of annual streamflow, and almost one-half of annual fluxes of Na and SiO2 in the stream; thus, flushing of old water by new water (snowmelt) is an important component of chemostatic behavior. Hydrologic flushing of subsurface materials further induces chemostatic behavior by reducing mineral saturation indices and increasing reactive mineral surface area, which stimulate mineral weathering rates. CO2 consumption by carbonic acid mediated mineral weathering was quantified using mass-balance calculations; results indicated that silicate mineral weathering was responsible for approximately two-thirds of annual CO2 consumption, and carbonate weathering was responsible for the remaining one-third. CO2 consumption was strongly dependent on annual precipitation and temperature; these relations were captured in a simple statistical model that accounted for 71% of the annual variation in CO2 consumption via mineral weathering in Loch Vale.

The cooling rate dependence of cation distributions in CoFe2O4

NASA Technical Reports Server (NTRS)

De Guire, Mark R.; O'Handley, Robert C.; Kalonji, Gretchen

1989-01-01

The room-temperature cation distributions in bulk CoFe2O4 samples, cooled at rates between less than 0.01 and about 1000 C/sec, have been determined using Mossbauer spectroscopy in an 80-kOe magnetic field. With increasing cooling rate, the quenched structure departs increasingly from the mostly ordered cation distribution ordinarily observed at room temperature. However, the cation disorder appears to saturate just short of a random distribution at very high cooling rates. These results are interpreted in terms of a simple relaxation model of cation redistribution kinetics. The disordered cation distributions should lead to increased magnetization and decreased coercivity in CoFe2O4.

Scaling the amplitudes of the circadian pattern of resting oxygen consumption, body temperature and heart rate in mammals.

PubMed

Mortola, Jacopo P; Lanthier, Clement

2004-09-01

We questioned whether the amplitudes of the circadian pattern of body temperature (T(b)), oxygen consumption (V (O(2))) and heart rate (HR) changed systematically among species of different body weight (W). Because bodies of large mass have a greater heat capacitance than those of smaller mass, if the relative amplitude (i.e., amplitude/mean value) of metabolic rate was constant, one would expect the T(b) oscillation to decrease with the increase in the species W. We compiled data of T(b), V (O(2)) and HR from a literature survey of over 200 studies that investigated the circadian pattern of these parameters. Monotremata, Marsupials and Chiroptera, were excluded because of their characteristically low metabolic rate and T(b). The peak-trough ratios of V (O(2)) (42 species) and HR (35 species) averaged, respectively, 1.57+/-0.08, and 1.35+/-0.07, and were independent of W. The daily high values of T(b) did not change, while the daily low T(b) values slightly increased, with the species W; hence, the high-low T(b) difference (57 species) decreased with W (3.3 degrees C.W(-0.13)). However, the decrease in T(b) amplitude with W was much less than expected from physical principles, and the high-low T(b) ratio remained significantly above unity even in the largest mammals. Thus, it appears that in mammals, despite the huge differences in physical characteristics, the amplitude of the circadian pattern is a fixed (for V (O(2)) and HR), or almost fixed (for T(b)), fraction of the 24-h mean value. Presumably, the amplitudes of the oscillations are controlled parameters of physiological significance.

Low toxicity of HfO2, SiO2, Al2O3 and CeO2 nanoparticles to the yeast, Saccharomyces cerevisiae.

PubMed

García-Saucedo, Citlali; Field, James A; Otero-Gonzalez, Lila; Sierra-Álvarez, Reyes

2011-09-15

Increasing use of nanomaterials necessitates an improved understanding of their potential impact on environment health. This study evaluated the cytotoxicity of nanosized HfO(2), SiO(2), Al(2)O(3) and CeO(2) towards the eukaryotic model organism Saccharomyces cerevisiae, and characterized their state of dispersion in bioassay medium. Nanotoxicity was assessed by monitoring oxygen consumption in batch cultures and by analysis of cell membrane integrity. CeO(2), Al(2)O(3), and HfO(2) nanoparticles were highly unstable in yeast medium and formed micron-sized, settleable agglomerates. A non-toxic polyacrylate dispersant (Dispex A40) was used to improve nanoparticle stability and determine the impact of enhanced dispersion on toxicity. None of the NPs tested without dispersant inhibited O(2) uptake by yeast at concentrations as high as 1000 mg/L. Dispersant supplementation only enhanced the toxicity of CeO(2) (47% at 1000 mg/L). Dispersed SiO(2) and Al(2)O(3) (1000 mg/L) caused cell membrane damage, whereas dispersed HfO(2) and CeO(2) did not cause significant disruption of membrane integrity at the same concentration. These results suggest that the O(2) uptake inhibition observed with dispersed CeO(2) NPs was not due to reduced cell viability. This is the first study evaluating toxicity of nanoscale HfO(2), SiO(2), Al(2)O(3) and CeO(2) to S. cerevisiae. Overall the results obtained demonstrate that these nanomaterials display low or no toxicity to yeast. Copyright © 2011 Elsevier B.V. All rights reserved.

Temperature dependence of O2 consumption; opposite effects of leptin and etomoxir on respiratory quotient in mice.

PubMed

Högberg, Helena; Engblom, Lars; Ekdahl, Asa; Lidell, Veronica; Walum, Erik; Alberts, Peteris

2006-04-01

The aims were to compare the temperature dependence of the metabolic rate in young ob/ob mice with that in mature ob/ob and db/db mice and to examine the effect on the metabolic substrate preference of leptin and etomoxir in ob/ob, C57BL/6J (wild-type), and db/db mice. In vivo oxygen consumption and carbon dioxide production were continuously measured by indirect calorimetry, and body temperature and total locomotor activity were measured by an implanted transponder. Leptin, etomoxir, or vehicle was administered intraperitoneally. The temperature dependence of the metabolic rate of mature ob/ob and db/db mice were similar to that in wild-type mice. In young 6-week-old ob/ob mice, the metabolic rate was almost doubled at 15 degrees C. Leptin (2 x 3 mg/kg) decreased the respiratory quotient (RQ) and carbon dioxide production but did not alter oxygen consumption, body temperature, or locomotor activity in ob/ob and C57BL/6J mice and had no effect in the db/db mice. Etomoxir (2 x 30 mg/kg) enhanced RQ and decreased oxygen consumption, carbon dioxide production, and body temperature in ob/ob, C57BL/6J, and db/db mice. Total locomotor activity was reduced in ob/ob and C57BL/6J mice. In young ob/ob mice, the temperature sensitivity was enhanced compared with mature mice. Leptin and etomoxir had opposite effects on metabolic substrate preference. Leptin and lowered environmental temperature increased the relative fat oxidation as indicated by decreased RQ, possibly through activation of the sympathetic nervous system.

CO2/H2O adsorption equilibrium and rates on metal-organic frameworks: HKUST-1 and Ni/DOBDC.

PubMed

Liu, Jian; Wang, Yu; Benin, Annabelle I; Jakubczak, Paulina; Willis, Richard R; LeVan, M Douglas

2010-09-07

Metal-organic frameworks (MOFs) have recently attracted intense research interest because of their permanent porous structures, huge surface areas, and potential applications as novel adsorbents and catalysts. In order to provide a basis for consideration of MOFs for removal of carbon dioxide from gases containing water vapor, such as flue gas, we have studied adsorption equilibrium of CO(2), H(2)O vapor, and their mixtures and also rates of CO(2) adsorption in two MOFs: HKUST-1 (CuBTC) and Ni/DOBDC (CPO-27-Ni or Ni/MOF-74). The MOFs were synthesized via solvothermal methods, and the as-synthesized products were solvent exchanged and regenerated before experiments. Pure component adsorption equilibria and CO(2)/H(2)O binary adsorption equilibria were studied using a volumetric system. The effects of H(2)O adsorption on CO(2) adsorption for both MOF samples were determined, and the results for 5A and NaX zeolites were included for comparison. The hydrothermal stabilities for the two MOFs over the course of repetitive measurements of H(2)O and CO(2)/H(2)O mixture equilibria were also studied. CO(2) adsorption rates from helium for the MOF samples were investigated by using a unique concentration-swing frequency response (CSFR) system. Mass transfer into the MOFs is rapid with the controlling resistance found to be macropore diffusion, and rate parameters were established for the mechanism.

Lake Metabolism: Comparison of Lake Metabolic Rates Estimated from a Diel CO2- and the Common Diel O2-Technique.

PubMed

Peeters, Frank; Atamanchuk, Dariia; Tengberg, Anders; Encinas-Fernández, Jorge; Hofmann, Hilmar

2016-01-01

Lake metabolism is a key factor for the understanding of turnover of energy and of organic and inorganic matter in lake ecosystems. Long-term time series on metabolic rates are commonly estimated from diel changes in dissolved oxygen. Here we present long-term data on metabolic rates based on diel changes in total dissolved inorganic carbon (DIC) utilizing an open-water diel CO2-technique. Metabolic rates estimated with this technique and the traditional diel O2-technique agree well in alkaline Lake Illmensee (pH of ~8.5), although the diel changes in molar CO2 concentrations are much smaller than those of the molar O2 concentrations. The open-water diel CO2- and diel O2-techniques provide independent measures of lake metabolic rates that differ in their sensitivity to transport processes. Hence, the combination of both techniques can help to constrain uncertainties arising from assumptions on vertical fluxes due to gas exchange and turbulent diffusion. This is particularly important for estimates of lake respiration rates because these are much more sensitive to assumptions on gradients in vertical fluxes of O2 or DIC than estimates of lake gross primary production. Our data suggest that it can be advantageous to estimate respiration rates assuming negligible gradients in vertical fluxes rather than including gas exchange with the atmosphere but neglecting vertical mixing in the water column. During two months in summer the average lake net production was close to zero suggesting at most slightly autotrophic conditions. However, the lake emitted O2 and CO2 during the entire time period suggesting that O2 and CO2 emissions from lakes can be decoupled from the metabolism in the near surface layer.

Lake Metabolism: Comparison of Lake Metabolic Rates Estimated from a Diel CO2- and the Common Diel O2-Technique

PubMed Central

Peeters, Frank; Atamanchuk, Dariia; Tengberg, Anders; Encinas-Fernández, Jorge; Hofmann, Hilmar

2016-01-01

Lake metabolism is a key factor for the understanding of turnover of energy and of organic and inorganic matter in lake ecosystems. Long-term time series on metabolic rates are commonly estimated from diel changes in dissolved oxygen. Here we present long-term data on metabolic rates based on diel changes in total dissolved inorganic carbon (DIC) utilizing an open-water diel CO2-technique. Metabolic rates estimated with this technique and the traditional diel O2-technique agree well in alkaline Lake Illmensee (pH of ~8.5), although the diel changes in molar CO2 concentrations are much smaller than those of the molar O2 concentrations. The open-water diel CO2- and diel O2-techniques provide independent measures of lake metabolic rates that differ in their sensitivity to transport processes. Hence, the combination of both techniques can help to constrain uncertainties arising from assumptions on vertical fluxes due to gas exchange and turbulent diffusion. This is particularly important for estimates of lake respiration rates because these are much more sensitive to assumptions on gradients in vertical fluxes of O2 or DIC than estimates of lake gross primary production. Our data suggest that it can be advantageous to estimate respiration rates assuming negligible gradients in vertical fluxes rather than including gas exchange with the atmosphere but neglecting vertical mixing in the water column. During two months in summer the average lake net production was close to zero suggesting at most slightly autotrophic conditions. However, the lake emitted O2 and CO2 during the entire time period suggesting that O2 and CO2 emissions from lakes can be decoupled from the metabolism in the near surface layer. PMID:28002477

High-gain subnanowatt power consumption hybrid complementary logic inverter with WSe2 nanosheet and ZnO nanowire transistors on glass.

PubMed

Shokouh, Seyed Hossein Hosseini; Pezeshki, Atiye; Ali Raza, Syed Raza; Lee, Hee Sung; Min, Sung-Wook; Jeon, Pyo Jin; Shin, Jae Min; Im, Seongil

2015-01-07

A 1D-2D hybrid complementary logic inverter comprising of ZnO nanowire and WSe2 nanosheet field-effect transistors (FETs) is fabricated on glass, which shows excellent static and dynamic electrical performances with a voltage gain of ≈60, sub-nanowatt power consumption, and at least 1 kHz inverting speed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Upland Trees Contribute to Exchange of Nitrous Oxide (N2O) in Forest Ecosystems

NASA Astrophysics Data System (ADS)

Tian, H.; Thompson, R.; Canadell, J.; Winiwarter, W.; Machacova, K.; Maier, M.; Halmeenmäki, E.; Svobodova, K.; Lang, F.; Pihlatie, M.; Urban, O.

2017-12-01

beech bark (lichens, mosses and algae) was quantified. All the organisms were net N2O sinks at full rehydration with consumption rates comparable to stem consumption rates. All tree species studied contribute to N2O exchange in forest ecosystems and these fluxes have to be included in the forest N2O emission inventories.

Vibrational energy transfer and relaxation in O2 and H2O.

PubMed

Huestis, David L

2006-06-01

Near-resonant vibrational energy exchange between oxygen and water molecules is an important process in the Earth's atmosphere, combustion chemistry, and the chemical oxygen iodine laser (COIL). The reactions in question are (1) O2(1) + O2(0) --> O2(0) + O2(0); (2) O2(1) + H2O(000) --> O2(0) + H2O(000); (3) O2(1) + H2O(000) <--> O2(0) + H2O(010); (4) H2O(010) + H2O(000) --> H2O(000) + H2O(000); and (5) H2O(010) + O2(0) --> H2O(000) + O2(0). Reanalysis of the data available in the chemical kinetics literature provides reliable values for rate coefficients for reactions 1 and 4 and strong evidence that reactions 2 and 5 are slow in comparison with reaction 3. Analytical solution of the chemical rate equations shows that previous attempts to measure the rate of reaction 3 are unreliable unless the water mole fraction is higher than 1%. Reanalysis of data from the only experiment satisfying this constraint provides a rate coefficient of (5.5 +/- 0.4) x 10(-13) cm3/s at room temperature, between the values favored by the atmospheric and laser modeling communities.

Reflected shock tube studies of high-temperature rate constants for OH + NO2 --> HO2 + NO and OH + HO2 --> H2O + O2.

PubMed

Srinivasan, Nanda K; Su, Meng-Chih; Sutherland, James W; Michael, Joe V; Ruscic, Branko

2006-06-01

The motivation for the present study comes from the preceding paper where it is suggested that accepted rate constants for OH + NO2 --> NO + HO2 are high by approximately 2. This conclusion was based on a reevaluation of heats of formation for HO2, OH, NO, and NO2 using the Active Thermochemical Table (ATcT) approach. The present experiments were performed in C2H5I/NO2 mixtures, using the reflected shock tube technique and OH-radical electronic absorption detection (at 308 nm) and using a multipass optical system. Time-dependent profile decays were fitted with a 23-step mechanism, but only OH + NO2, OH + HO2, both HO2 and NO2 dissociations, and the atom molecule reactions, O + NO2 and O + C2H4, contributed to the decay profile. Since all of the reactions except the first two are known with good accuracy, the profiles were fitted by varying only OH + NO2 and OH + HO2. The new ATcT approach was used to evaluate equilibrium constants so that back reactions were accurately taken into account. The combined rate constant from the present work and earlier work by Glaenzer and Troe (GT) is k(OH+NO2) = 2.25 x 10(-11) exp(-3831 K/T) cm3 molecule(-1) s(-1), which is a factor of 2 lower than the extrapolated direct value from Howard but agrees well with NO + HO2 --> OH + NO2 transformed with the updated equilibrium constants. Also, the rate constant for OH + HO2 suitable for combustion modeling applications over the T range (1200-1700 K) is (5 +/- 3) x 10(-11) cm3 molecule(-1) s(-1). Finally, simulating previous experimental results of GT using our updated mechanism, we suggest a constant rate for k(HO2+NO2) = (2.2 +/- 0.7) x 10(-11) cm3 molecule(-1) s(-1) over the T range 1350-1760 K.

Meat consumption in São Paulo-Brazil: trend in the last decade.

PubMed

de Carvalho, Aline Martins; César, Chester Luiz Galvão; Fisberg, Regina Mara; Marchioni, Dirce Maria

2014-01-01

To characterize trends in meat consumption, and verify the percentage of excessive red and processed meat consumption in the last decade in São Paulo, Brazil. Cross-sectional weighted data from the Health Survey for São Paulo, conducted in São Paulo, Brazil among people aged 12 years and older. Diet was assessed by two 24-hour recalls in each survey. Usual meat consumption was estimated by Multiple Source Method. Wald tests were used to compare means across survey years. Data were collected from adolescents, adults, and elderly using a representative, complex, multistage probability-based survey in 2003 and in 2008 in São Paulo, southeast of Brazil. 2631 Brazilians were studied in 2003 and 1662 in 2008. Daily mean of red and processed meat consumption was 100 g/day in 2003, and 113 g/day in 2008. Excessive red and processed meat consumption was observed in almost 75% of the subjects, especially among adolescents in both surveys. Beef represented the largest proportion of meat consumed, followed by poultry, pork and fish in both surveys. Daily red and processed meat consumption was higher in 2008 than in 2003, and almost the entire population consumed more than what is recommended by World Cancer Research Fund. Public health strategies are needed, in order to reduce red and processed meat consumption to the recommended amounts, for a healthy diet.

Determination of the Rate Coefficients of the SO2 plus O plus M yields SO3 plus M Reaction

NASA Technical Reports Server (NTRS)

Hwang, S. M.; Cooke, J. A.; De Witt, K. J.; Rabinowitz, M. J.

2010-01-01

Rate coefficients of the title reaction R(sub 31) (SO2 +O+M yields SO3 +M) and R(sub 56) (SO2 + HO2 yields SO3 +OH), important in the conversion of S(IV) to S(VI),were obtained at T =970-1150 K and rho (sub ave) = 16.2 micro mol/cubic cm behind reflected shock waves by a perturbation method. Shock-heated H2/ O2/Ar mixtures were perturbed by adding small amounts of SO2 (1%, 2%, and 3%) and the OH temporal profiles were then measured using laser absorption spectroscopy. Reaction rate coefficients were elucidated by matching the characteristic reaction times acquired from the individual experimental absorption profiles via simultaneous optimization of k(sub 31) and k(sub 56) values in the reaction modeling (for satisfactory matches to the observed characteristic times, it was necessary to take into account R(sub 56)). In the experimental conditions of this study, R(sub 31) is in the low-pressure limit. The rate coefficient expressions fitted using the combined data of this study and the previous experimental results are k(sub 31,0)/[Ar] = 2.9 10(exp 35) T(exp ?6.0) exp(?4780 K/T ) + 6.1 10(exp 24) T(exp ?3.0) exp(?1980 K/T ) cm(sup 6) mol(exp ?2)/ s at T = 300-2500 K; k(sub 56) = 1.36 10(exp 11) exp(?3420 K/T ) cm(exp 3)/mol/s at T = 970-1150 K. Computer simulations of typical aircraft engine environments, using the reaction mechanism with the above k(sub 31,0) and k(sub 56) expressions, gave the maximum S(IV) to S(VI) conversion yield of ca. 3.5% and 2.5% for the constant density and constant pressure flow condition, respectively. Moreover, maximum conversions occur at rather higher temperatures (?1200 K) than that where the maximum k(sub 31,0) value is located (approximately 800 K). This is because the conversion yield is dependent upon not only the k(sup 31,0) and k(sup 56) values (production flux) but also the availability of H, O, and HO2 in the system (consumption flux).

Direct Dynamics Simulation of the Thermal 3CH2 + 3O2 Reaction. Rate Constant and Product Branching Ratios.

PubMed

Lakshmanan, Sandhiya; Pratihar, Subha; Machado, Francisco B C; Hase, William L

2018-05-31

The reaction of 3 CH 2 with 3 O 2 is of fundamental importance in combustion, and the reaction is complex as a result of multiple extremely exothermic product channels. In the present study, direct dynamics simulations were performed to study the reaction on both the singlet and triplet potential energy surfaces (PESs). The simulations were performed at the UM06/6-311++G(d,p) level of theory. Trajectories were calculated at a temperature of 300 K, and all reactive trajectories proceeded through the carbonyl oxide Criegee intermediate, CH 2 OO, on both the singlet and triplet PESs. The triplet surface leads to only one product channel, H 2 CO + O( 3 P), while the singlet surface leads to eight product channels with their relative importance as CO + H 2 O > CO + OH + H ∼ H 2 CO + O( 1 D) > HCO + OH ∼ CO 2 + H 2 ∼ CO + H 2 + O( 1 D) > CO 2 + H + H > HCO + O( 1 D) + H. The reaction on the singlet PES is barrierless, consistent with experiment, and the total rate constant on the singlet surface is (0.93 ± 0.22) × 10 -12 cm 3 molecule -1 s -1 in comparison to the recommended experimental rate constant of 3.3 × 10 -12 cm 3 molecule -1 s -1 . The simulation product yields for the singlet PES are compared with experiment, and the most significant differences are for H, CO 2 , and H 2 O. The reaction on the triplet surface is also barrierless, inconsistent with experiment. A discussion is given of the need for future calculations to address (1) the barrier on the triplet PES for 3 CH 2 + 3 O 2 → 3 CH 2 OO, (2) the temperature dependence of the 3 CH 2 + 3 O 2 reaction rate constant and product branching ratios, and (3) the possible non-RRKM dynamics of the 1 CH 2 OO Criegee intermediate.

The study of glass transition temperature in Sb-V2O5-TeO2 glasses at different heating rates

NASA Astrophysics Data System (ADS)

Souri, Dariush

2015-12-01

The glass transition of xSb-(60 - x)V2O5-40TeO2 glasses with 0 < x <15 (in mol%) at different heating rates ( φ = 3-12 K/min) has been studied using differential scanning calorimetry. The glass transition temperature ( T g) and crystallization temperature ( T cr) of these glasses have been determined. The effects of the heating rate and the Sb content on T g have been discussed. It has been observed that the transition region shifts to higher temperatures when the measuring time is reduced. The compositional dependence of T g has been determined and so an empirical equation has been deduced relating the glass transition temperature with the Sb concentration. Also, the value of glass-forming tendency has been studied for the present glasses.

Oxygen consumption of a pneumatically controlled ventilator in a field anesthesia machine.

PubMed

Szpisjak, Dale F; Javernick, Elizabeth N; Kyle, Richard R; Austin, Paul N

2008-12-01

Field anesthesia machines (FAM) have been developed for remote locations where reliable supplies of compressed medical gases or electricity may be absent. In place of electricity, pneumatically controlled ventilators use compressed gas to power timing circuitry and actuate valves. We sought to determine the total O(2) consumption and ventilator gas consumption (drive gas [DG] plus pneumatic control [PC] gas) of a FAM's pneumatically controlled ventilator in mechanical models of high (HC) and low (LC) total thoracic compliance. The amount of total O(2) consumed by the Magellan-2200 (Oceanic Medical Products, Atchison, KS) FAM with pneumatically controlled ventilator was calculated using the ideal gas law and the measured mass of O(2) consumed from E cylinders. DG to the bellows canister assembly was measured with the Wright Respirometer Mk 8 (Ferraris Respiratory Europe, Hertford, UK). PC gas consumption was calculated by subtracting DG and fresh gas flow (FGF) from the total O(2) consumed from the E cylinder. The delivered tidal volume (V(T)) was measured with a pneumotach (Hans Rudolph, KS City, MO). Three different V(T) were tested (500, 750, and 1000 mL) with two lung models (HC and LC) using the Vent Aid Training Test Lung (MI Instruments, Grand Rapids, MI). Respiratory variables included an I:E of 1:2, FGF of 1 L/min, and respiratory rate of 10 breaths/min. Total O(2) consumption was directly proportional to V(T) and inversely proportional to compliance. The smallest total O(2) consumption rate (including FGF) was 9.3 +/- 0.4 L/min in the HC-500 model and the largest was 15.9 +/- 0.5 L/min in the LC-1000 model (P < 0.001). The mean PC circuitry consumption was 3.9 +/- 0.24 L/min or 390 mL +/- 24 mL/breath. To prepare for loss of central DG supply, patient safety will be improved by estimating cylinder duration for low total thoracic compliance. Using data from the smaller compliance and greatest V(T) model (LC-1000), a full O(2) E cylinder would be depleted in

New electron-energy transfer rates for vibrational excitation of O2

NASA Astrophysics Data System (ADS)

Jones, D. B.; Campbell, L.; Bottema, M. J.; Brunger, M. J.

2003-09-01

We report on our computation of electron-energy transfer rates for vibrational excitation of O2. This work was necessitated by inadequacies in the electron-impact cross section databases employed in previous studies and, in one case, an inaccurate approximate formulation to the rate equation. Both these inadequacies led to incorrect energy transfer rates being published in the literature. We also demonstrate the importance of using cross sections that encompass an energy range that is extended enough to appropriately describe the environment under investigation.

The pH dependency of N-converting enzymatic processes, pathways and microbes: effect on net N2 O production.

PubMed

Blum, Jan-Michael; Su, Qingxian; Ma, Yunjie; Valverde-Pérez, Borja; Domingo-Félez, Carlos; Jensen, Marlene Mark; Smets, Barth F

2018-05-01

Nitrous oxide (N 2 O) is emitted during microbiological nitrogen (N) conversion processes, when N 2 O production exceeds N 2 O consumption. The magnitude of N 2 O production vs. consumption varies with pH and controlling net N 2 O production might be feasible by choice of system pH. This article reviews how pH affects enzymes, pathways and microorganisms that are involved in N-conversions in water engineering applications. At a molecular level, pH affects activity of cofactors and structural elements of relevant enzymes by protonation or deprotonation of amino acid residues or solvent ligands, thus causing steric changes in catalytic sites or proton/electron transfer routes that alter the enzymes' overall activity. Augmenting molecular information with, e.g., nitritation or denitrification rates yields explanations of changes in net N 2 O production with pH. Ammonia oxidizing bacteria are of highest relevance for N 2 O production, while heterotrophic denitrifiers are relevant for N 2 O consumption at pH > 7.5. Net N 2 O production in N-cycling water engineering systems is predicted to display a 'bell-shaped' curve in the range of pH 6.0-9.0 with a maximum at pH 7.0-7.5. Net N 2 O production at acidic pH is dominated by N 2 O production, whereas N 2 O consumption can outweigh production at alkaline pH. Thus, pH 8.0 may be a favourable pH set-point for water treatment applications regarding net N 2 O production. © 2018 Society for Applied Microbiology and John Wiley & Sons Ltd.

Particle emission rates during electrostatic spray deposition of TiO2 nanoparticle-based photoactive coating.

PubMed

Koivisto, Antti J; Jensen, Alexander C Ø; Kling, Kirsten I; Kling, Jens; Budtz, Hans Christian; Koponen, Ismo K; Tuinman, Ilse; Hussein, Tareq; Jensen, Keld A; Nørgaard, Asger; Levin, Marcus

2018-01-05

Here, we studied the particle release rate during Electrostatic spray deposition of anatase-(TiO 2 )-based photoactive coating onto tiles and wallpaper using a commercially available electrostatic spray device. Spraying was performed in a 20.3m 3 test chamber while measuring concentrations of 5.6nm to 31μm-size particles and volatile organic compounds (VOC), as well as particle deposition onto room surfaces and on the spray gun user hand. The particle emission and deposition rates were quantified using aerosol mass balance modelling. The geometric mean particle number emission rate was 1.9×10 10 s -1 and the mean mass emission rate was 381μgs -1 . The respirable mass emission-rate was 65% lower than observed for the entire measured size-range. The mass emission rates were linearly scalable (±ca. 20%) to the process duration. The particle deposition rates were up to 15h -1 for <1μm-size and the deposited particles consisted of mainly TiO 2 , TiO 2 mixed with Cl and/or Ag, TiO 2 particles coated with carbon, and Ag particles with size ranging from 60nm to ca. 5μm. As expected, no significant VOC emissions were observed as a result of spraying. Finally, we provide recommendations for exposure model parameterization. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

MnO2-GO double-shelled sulfur (S@MnO2@GO) as a cathode for Li-S batteries with improved rate capability and cyclic performance

NASA Astrophysics Data System (ADS)

Huang, Xingkang; Shi, Keying; Yang, Joseph; Mao, George; Chen, Junhong

2017-07-01

Sulfur cathodes have attracted much attention recently because of their high energy density and power density. However, sulfur possesses very poor electrical conductivity, and lithium polysulfides, resulting from the lithiation of sulfur, are prone to dissolving into electrolytes, which leads to the loss of active materials and poor cyclic performance of the sulfur cathodes. Here we report an MnO2-graphene oxide (GO) double-shelled sulfur (S@MnO2@GO) with improved rate capability and cyclic performance, in which we propose a new reaction using sulfur-reducing KMnO4 to produce MnO2 that covers the surface of the excess sulfur in situ. The resulting MnO2 with honeycomb-like morphology provides excellent voids for storing polysulfides. The outermost GO was assembled to block the open pores of MnO2, thereby minimizing the opportunity for polysulfides to leach into the electrolytes. The GO significantly improved the electrical conductivity of the sulfur cathode, and the S@MnO2@GO exhibited excellent rate capability and long cycle life.

Quantifying consumption rates of dissolved oxygen along bed forms

NASA Astrophysics Data System (ADS)

Boano, Fulvio; De Falco, Natalie; Arnon, Shai

2016-04-01

Streambed interfaces represent hotspots for nutrient transformations because they host different microbial species, and the evaluation of these reaction rates is important to assess the fate of nutrients in riverine environments. In this work we analyze a series of flume experiments on oxygen demand in dune-shaped hyporheic sediments under losing and gaining flow conditions. We employ a new modeling code to quantify oxygen consumption rates from observed vertical profiles of oxygen concentration. The code accounts for transport by molecular diffusion and water advection, and automatically determines the reaction rates that provide the best fit between observed and modeled concentration values. The results show that reaction rates are not uniformly distributed across the streambed, in agreement with the expected behavior predicted by hyporheic exchange theory. Oxygen consumption was found to be highly influenced by the presence of gaining or losing flow conditions, which controlled the delivery of labile DOC to streambed microorganisms.

Heliocentric distance dependencies of the C2 lifetime and C2 parent production rate in comet P/Brorsen-Metcalf (1989o)

NASA Technical Reports Server (NTRS)

Lazzarin, M.; Tozzi, Giau Paolo; Barbieri, C.; Festou, Michel C.

1992-01-01

Comet P/Brorsen-Metcalf (1989o) has been extensively observed in the visible and in the ultraviolet during its latest apparition of summer 1989. In this paper we report a preliminary determination of the C2 production rates and lifetimes and we compare those rates to the H2O production rates obtained from UV data.

The Rate-Limiting Step of O2 Activation in the α-Ketoglutarate Oxygenase Factor Inhibiting Hypoxia Inducible Factor

PubMed Central

2015-01-01

Factor inhibiting HIF (FIH) is a cellular O2-sensing enzyme, which hydroxylates the hypoxia inducible factor-1α. Previously reported inverse solvent kinetic isotope effects indicated that FIH limits its overall turnover through an O2 activation step (HangaskyJ. A., SabanE., and KnappM. J. (2013) Biochemistry52, 1594−160223351038). Here we characterize the rate-limiting step for O2 activation by FIH using a suite of mechanistic probes on the second order rate constant kcat/KM(O2). Steady-state kinetics showed that the rate constant for O2 activation was slow (kcat/KM(O2)app = 3500 M–1 s–1) compared with other non-heme iron oxygenases, and solvent viscosity assays further excluded diffusional encounter with O2 from being rate limiting on kcat/KM(O2). Competitive oxygen-18 kinetic isotope effect measurements (18kcat/KM(O2) = 1.0114(5)) indicated that the transition state for O2 activation resembled a cyclic peroxohemiketal, which precedes the formation of the ferryl intermediate observed in related enzymes. We interpret this data to indicate that FIH limits its overall activity at the point of the nucleophilic attack of Fe-bound O2— on the C-2 carbon of αKG. Overall, these results show that FIH follows the consensus mechanism for αKG oxygenases, suggesting that FIH may be an ideal enzyme to directly access steps involved in O2 activation among the broad family of αKG oxygenases. PMID:25423620

Reaction of H2 with O2 in Excited Electronic States: Reaction Pathways and Rate Constants.

PubMed

Pelevkin, Alexey V; Loukhovitski, Boris I; Sharipov, Alexander S

2017-12-21

Comprehensive quantum chemical analysis with the use of the multireference state-averaged complete active space self-consistent field approach was carried out to study the reactions of H 2 with O 2 in a 1 Δ g , b 1 Σ g + , c 1 Σ u - , and A' 3 Δ u electronically excited states. The energetically favorable reaction pathways and possible intersystem crossings have been revealed. The energy barriers were refined employing the extended multiconfiguration quasi-degenerate second-order perturbation theory. It has been shown that the interaction of O 2 (a 1 Δ g ) and O 2 (A' 3 Δ u ) with H 2 occurs through the H-abstraction process with relatively low activation barriers that resulted in the formation of the HO 2 molecule in A″ and A' electronic states, respectively. Meanwhile, molecular oxygen in singlet sigma states (b 1 Σ g + and c 1 Σ u - ) was proved to be nonreactive with respect to the molecular hydrogen. Appropriate rate constants for revealed reaction and quenching channels have been estimated using variational transition-state theory including corrections for the tunneling effect, possible nonadiabatic transitions, and anharmonicity of vibrations for transition states and reactants. It was demonstrated that the calculated reaction rate constant for the H 2 + O 2 (a 1 Δ g ) process is in reasonable agreement with known experimental data. The Arrhenius approximations for these processes have been proposed for the temperature range T = 300-3000 K.

Comparing N2O emissions at varying N rates from irrigated and rainfed corn in the US Midwest

NASA Astrophysics Data System (ADS)

Millar, N.; Kahmark, K.; Basso, B.; Robertson, G. P.

2011-12-01

Global N2O emissions from agriculture are estimated to be ~2.8 Pg CO2e yr-1 accounting for 60% of total anthropogenic emissions. N2O is the largest contributor to the GHG burden of cropping systems in the US, with annual estimated emissions of ~0.5 Tg primarily due to N fertilizer inputs and other soil management activities. Currently 23 million acres of corn, soybean and wheat are irrigated annually in the US with increased N2O emissions due to the practice likely under-reported in GHG inventories. Here we compare N2O emissions and yield from irrigated and rainfed corn at varying N rates between 0 and 246 kg N ha-1 from the Kellogg Biological Station in SW Michigan. Initial results show that N2O emissions increase with increasing N rate and are significantly higher from irrigated corn compared to rainfed corn at the same N rate. At increasing N rates daily emissions following an irrigation event were between 2.4 - 77.5 g N2O-N ha-1 from irrigated corn and 1.6 - 13.0 g N2O-N ha-1 from rainfed corn. Emissions data from automated and static chambers will be presented and trade-offs between N2O emissions, N fertilizer rate, crop yield and irrigation practice will be evaluated from an environmental and economic standpoint.

Rates of volcanic CO2 degassing from airborne determinations of SO2 Emission rates and plume CO2SO2: test study at Pu′u ′O′o Cone, Kilauea Volcano, Hawaii

USGS Publications Warehouse

Gerlach, Terrence M.; McGee, Kenneth A.; Sutton, A. Jefferson; Elias, Tamar

1998-01-01

We present an airborne method that eliminates or minimizes several disadvantages of the customary plume cross-section sampling method for determining volcanic CO2 emission rates. A LI-COR CO2analyzer system (LICOR), a Fourier transform infrared spectrometer system (FTIR), and a correlation spectrometer (COSPEC) were used to constrain the plume CO2/SO2 and the SO2 emission rate. The method yielded a CO2 emission rate of 300 td−1 (metric tons per day) for Pu′u ′O′o cone, Kilauea volcano, on 19 September 1995. The CO2/SO2 of 0.20 determined from airborne LICOR and FTIR plume measurements agreed with the CO2/SO2 of 204 ground-based samples collected from vents over a 14-year period since the Pu′u ′O′o eruption began in January 1983.

High-rate capability of three-dimensionally ordered macroporous T-Nb2O5 through Li+ intercalation pseudocapacitance

NASA Astrophysics Data System (ADS)

Lou, Shuaifeng; Cheng, Xinqun; Wang, Long; Gao, Jinlong; Li, Qin; Ma, Yulin; Gao, Yunzhi; Zuo, Pengjian; Du, Chunyu; Yin, Geping

2017-09-01

Orthorhombic Niobium oxide (T-Nb2O5) has been regarded as a promising anode material for high-rate lithium ion batteries (LIBs) due to its potential to operate at high rates with improved safety and high theoretical capacity of 200 mA h g-1. Herein, three-dimensionally ordered macroporous (3DOM) T-Nb2O5, with mesoporous hierarchical structure, was firstly prepared by a simple approach employing self-assembly polystyrene (PS) microspheres as hard templates. The obtained T-Nb2O5 anode material presents obvious and highly-efficiency pseudocapacitive Li+ intercalation behaviour, which plays a dominant role in the kinetics of electrode process. As a result, rapid Li+ intercalation/de-intercalation are achieved, leading to excellent rate capability and long cycle life. The 3DOM T-Nb2O5 shows a remarkable high capacity of 106 and 77 mA h g-1 at the rate of 20C and 50C. The work presented herein holds great promise for future design of material structure, and demonstrates the great potential of T-Nb2O5 as a practical high-rate anode material for LIBs.

Isotopic exchange in mineral-fluid systems. IV. The crystal chemical controls on oxygen isotope exchange rates in carbonate-H 2O and layer silicate-H 2O systems

NASA Astrophysics Data System (ADS)

Cole, David R.

2000-03-01

Oxygen isotope exchange between minerals and water in systems far from chemical equilibrium is controlled largely by surface reactions such as dissolution-precipitation. In many cases, this behavior can be modeled adequately by a simple pseudo-first order rate model that accounts for changes in surface area of the solid. Previous modeling of high temperature isotope exchange data for carbonates, sulfates, and silicates indicated that within a given mineral group there appears to be a systematic relationship between rate and mineral chemistry. We tested this idea by conducting oxygen isotope exchange experiments in the systems, carbonate-H 2O and layer silicate-H 2O at 300 and 350°C, respectively. Witherite (BaCO 3), strontianite (SrCO 3) and calcite (CaCO 3) were reacted with pure H 2O for different lengths of time (271-1390 h) at 300°C and 100 bars. The layer silicates, chlorite, biotite and muscovite were reacted with H 2O for durations ranging from 132 to 3282 h at 350°C and 250 bars. A detailed survey of grain sizes and grain habits using scanning electron microscopy (SEM) indicated that grain regrowth occurred in all experiments to varying extents. Changes in the mean grain diameters were particularly significant in experiments involving withertite, strontianite and biotite. The variations in the extent of oxygen isotope exchange were measured as a function of time, and fit to a pseudo-first order rate model that accounted for the change in surface area of the solid during reaction. The isotopic rates (ln r) for the carbonate-H 2O system are -20.75 ± 0.44, -18.95 ± 0.62 and -18.51 ± 0.48 mol O m -2 s -1 for calcite, strontianite and witherite, respectively. The oxygen isotope exchange rates for layer silicate-H 2O systems are -23.99 ± 0.89, -23.14 ± 0.74 and -22.40 ± 0.66 mol O m -2 s -1 for muscovite, biotite and chlorite, respectively. The rates for the carbonate-H 2O systems increase in order from calcite to strontianite to witherite. This order

[Oxygen consumption rate and effects of hypoxia stress on enzyme activities of Sepiella maindron].

PubMed

Wang, Chun-lin; Wu, Dan-hua; Dong, Tian-ye; Jiang, Xia-min

2008-11-01

The oxygen consumption rate and suffocation point of Sepiella maindroni were determined through the measurement of dissolved oxygen in control and experimental respiration chambers by Winkler's method, and the changes of S. maindroni enzyme activities under different levels of hypoxia stress were studied. The results indicated that the oxygen consumption rate of S. maindroni exhibited an obvious diurnal fluctuation of 'up-down-up-down', and positively correlated with water temperature (16 degrees C-28 degrees C) and illumination (3-500 micromol x m(-2) x s(-1)) while negatively correlated with water pH (6.25-9.25). With increasing water salinity from 18.1 to 29.8, the oxygen consumption rate had a variation of 'up-down-up', being the lowest at salinity 24. 8. Female S. maindroni had a higher oxygen consumption rate than male S. maindroni. The suffocation point of S. maindroni decreased with its increasing body mass, and that of (38.70 +/- 0.52) g in mass was (0.9427 +/- 0.0318) mg x L(-1). With the increase of hypoxia stress, the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) decreased after an initial increase, lipase activity decreased, protease activity had a variation of 'decrease-increase-decrease', and lactate dehydrogenase (LDH) activity had a trend of increasing first and decreasing then. The enzyme activities were higher under hypoxia stress than under normal conditions.

[Effects of temperature and salinity on oxygen consumption rate and asphyxiation point of Sagitta crassa].

PubMed

Liu, Qing; Zhu, Hai-Yan; Liu, Fang; Ding, Zi-Yuan

2011-11-01

A laboratory test was conducted to study the effects of different temperature and salinity on the oxygen consumption rate and asphyxiation point of chaetognath Sagitta crassa. Both temperature and salinity had significant effects on the oxygen consumption rate (IO) and specific oxygen consumption rate (SO) of S. crassa. When the temperature raised from 5 degrees C to 25 degrees C, the IO and SO of S. crassa increased first, and then presented an obvious decreasing trend, with the regression function being y = 0.0058x3-0.2956x2 +4.415x-8.7816 (R2 = 0.99, P < 0.05) for IO and y = 0.0011x3-0.0546x2+0.8161x-1.6232 (R2 = 0.99, P < 0.05) for SO. The IO and SO at different temperature were in the ranges of 6.30-11.71 microg x ind(-1) x h(-1) and 1.22-2.16 microg x mg(-1) x h(-1), respectively, and the asphyxiation point was 4.18-6.87 mg x L(-1). When the salinity increased from 10 to 40, the IO and SO of S. crassa decreased gradually, with the regression function being y = -0.0068x2-0.1412x+21.702 (R2 = 0.89, P < 0.05) for IO and y = -0.0013x2 -0.0261x+ 4.0114 (R2 = 0.89, P < 0.05) for SO. The IO and SO at different salinity were in the ranges of 4.98-17.73 microg x ind(-1) x h(-1) and 0.92-3.56 microg x mg(-1) x h(-1), respectively, and the asphyxiation point was 4.02-6.24 mg x L(-1). Based on the differences in the oxygen consumption rate and asphyxiation point between S. crassa and other aquatic animals, it was concluded that S. crassa was a stenooxybiotic zooplankton species.

Surface Nitrification: A Major Uncertainty in Marine N2O Emissions

NASA Technical Reports Server (NTRS)

Zamora, Lauren M.; Oschlies, Andreas

2014-01-01

The ocean is responsible for up to a third of total global nitrous oxide (N2O) emissions, but uncertainties in emission rates of this potent greenhouse gas are high (approaching 100%). Here we use a marine biogeochemical model to assess six major uncertainties in estimates of N2O production, thereby providing guidance in how future studies may most effectively reduce uncertainties in current and future marine N2O emissions. Potential surface N2O production from nitrification causes the largest uncertainty in N2O emissions (estimated up to approximately 1.6 Tg N/yr (sup -1) or 48% of modeled values), followed by the unknown oxygen concentration at which N2O production switches to N2O consumption (0.8 Tg N/yr (sup -1)or 24% of modeled values). Other uncertainties are minor, cumulatively changing regional emissions by less than 15%. If production of N2O by surface nitrification could be ruled out in future studies, uncertainties in marine N2O emissions would be halved.

Dutch courage? Effects of acute alcohol consumption on self-ratings and observer ratings of foreign language skills.

PubMed

Renner, Fritz; Kersbergen, Inge; Field, Matt; Werthmann, Jessica

2018-01-01

A popular belief is that alcohol improves the ability to speak in a foreign language. The effect of acute alcohol consumption on perceived foreign language performance and actual foreign language performance in foreign language learners has not been investigated. The aim of the current study was to test the effects of acute alcohol consumption on self-rated and observer-rated verbal foreign language performance in participants who have recently learned this language. Fifty native German speakers who had recently learned Dutch were randomized to receive either a low dose of alcohol or a control beverage that contained no alcohol. Following the experimental manipulation, participants took part in a standardized discussion in Dutch with a blinded experimenter. The discussion was audio-recorded and foreign language skills were subsequently rated by two native Dutch speakers who were blind to the experimental condition (observer-rating). Participants also rated their own individual Dutch language skills during the discussion (self-rating). Participants who consumed alcohol had significantly better observer-ratings for their Dutch language, specifically better pronunciation, compared with those who did not consume alcohol. However, alcohol had no effect on self-ratings of Dutch language skills. Acute alcohol consumption may have beneficial effects on the pronunciation of a foreign language in people who have recently learned that language.

Metabolically Derived Human Ventilation Rates: A Revised Approach Based Upon Oxygen Consumption Rates (Final Report, 2009)

EPA Science Inventory

EPA announced the availability of the final report, Metabolically Derived Human Ventilation Rates: A Revised Approach Based Upon Oxygen Consumption Rates. This report provides a revised approach for calculating an individual's ventilation rate directly from their oxygen c...

Gas Pressure Monitored Iodide-Catalyzed Decomposition Kinetics of H[subscript 2]O[subscript 2]: Initial-Rate and Integrated-Rate Methods in the General Chemistry Lab

ERIC Educational Resources Information Center

Nyasulu, Frazier; Barlag, Rebecca

2010-01-01

The reaction kinetics of the iodide-catalyzed decomposition of [subscript 2]O[subscript 2] using the integrated-rate method is described. The method is based on the measurement of the total gas pressure using a datalogger and pressure sensor. This is a modification of a previously reported experiment based on the initial-rate approach. (Contains 2…

Relationships between oxygen consumption rate, viability, and subsequent development of in vivo-derived porcine embryos.

PubMed

Sakagami, N; Nishida, K; Akiyama, K; Abe, H; Hoshi, H; Suzuki, C; Yoshioka, K

2015-01-01

Oxygen consumption rate of in vivo-derived porcine embryos was measured, and its value as an objective method for the assessment of embryo quality was evaluated. Embryos were surgically collected 5 or 6 days after artificial insemination (AI), and oxygen consumption rate of embryos was measured using an embryo respirometer. The average oxygen consumption rate (F × 10(14)/mol s(-1)) of the embryos that developed to the compacted morula stage on Day 5 (Day 0 = the day of artificial insemination) was 0.58 ± 0.03 (mean ± standard error of the mean). The Day-6 embryos had consumption rates of 0.56 ± 0.13, 0.87 ± 0.06, and 1.13 ± 0.07 at the early blastocyst, blastocyst, and expanded blastocyst stages, respectively, showing a gradual increase as the embryos developed. Just after collection, the average oxygen consumption rates of embryos that hatched and of those that did not hatch after culture were 0.60 ± 0.04 and 0.50 ± 0.04 for Day 5 (P = 0.08) and 1.05 ± 0.09 and 0.77 ± 0.05 for Day 6 (P < 0.05), respectively. The value and probability of discrimination by measuring the oxygen consumption rates of embryos to predict their hatching ability after culture were 0.56 and 63.6% for Day-5 embryos and 0.91 and 68.4% for Day-6 blastocysts, respectively. When Day-5 embryos were classified based on the oxygen consumption rate and then transferred non-surgically to recipient sows, three of the seven sows, to which embryos having a high oxygen consumption rate (≥ 0.59) were transferred, became pregnant and farrowed a total of 20 piglets. However, none of the four sows, to which embryos having low oxygen consumption rate (< 0.59) were transferred, became pregnant. These results suggest that the viability of in vivo-derived porcine embryos and subsequent development can be estimated by measuring the oxygen consumption rate. Copyright © 2015 Elsevier Inc. All rights reserved.

Oxygen consumption rate and mitochondrial density in human melanoma monolayer cultures and multicellular spheroids.

PubMed

Hystad, M E; Rofstad, E K

1994-05-15

Rate of oxygen consumption per cell has been shown in previous studies to decrease with increasing depth in the viable rim of multicellular spheroids initiated from rodent cells, human colon-carcinoma cells, and human glioma cells, due to progressive accumulation of quiescent cells during spheroid growth. The purpose of our work was to determine oxygen-consumption profiles in human melanoma spheroids. Monolayer cultures of 4 lines (BEX-c, COX-c, SAX-c, and WIX-c) and spheroid cultures of 2 lines (BEX-c and WIX-c) were subjected to investigation. Spheroids were initiated from monolayer cell cultures and grown in spinner flasks. Rate of oxygen consumption was measured with a Clarke-type electrode. Mitochondrial density was determined by stereological analysis of transmission electron micrographs. Thickness of viable rim and cell packing density were assessed by light microscopy of central spheroid sections. Cell-cycle distribution was determined by analysis of DNA histograms measured by flow cytometry. Cell volume was measured by an electronic particle counter. Rate of oxygen consumption per cell differed by a factor of approximately 1.8 between the 4 cell lines and was positively correlated to total volume of mitochondria per cell. Rate of oxygen consumption per cell and total volume of mitochondria per cell were equal for monolayer cell cultures, 600-microns spheroids and 1,200-microns spheroids of the same line. Mitochondrial density and location in the cell did not differ between cells at the spheroid surface, in the middle of the viable rim and adjacent to the central necrosis. Cell-cycle distribution, cell volume, and cell-packing density in the outer and inner halves of the viable rim were not significantly different. Consequently, the rate of oxygen consumption per cell in inner regions of the viable rim was probably equal to that at the spheroid surface, suggesting that oxygen diffusion distances may be shorter in some melanomas than in many other tumor

Optical properties of the Al2O3/SiO2 and Al2O3/HfO2/SiO2 antireflective coatings

NASA Astrophysics Data System (ADS)

Marszałek, Konstanty; Winkowski, Paweł; Jaglarz, Janusz

2014-01-01

Investigations of bilayer and trilayer Al2O3/SiO2 and Al2O3/HfO2/SiO2 antireflective coatings are presented in this paper. The oxide films were deposited on a heated quartz glass by e-gun evaporation in a vacuum of 5 × 10-3 [Pa] in the presence of oxygen. Depositions were performed at three different temperatures of the substrates: 100 °C, 200 °C and 300 °C. The coatings were deposited onto optical quartz glass (Corning HPFS). The thickness and deposition rate were controlled with Inficon XTC/2 thickness measuring system. Deposition rate was equal to 0.6 nm/s for Al2O3, 0.6 nm - 0.8 nm/s for HfO2 and 0.6 nm/s for SiO2. Simulations leading to optimization of the thin film thickness and the experimental results of optical measurements, which were carried out during and after the deposition process, have been presented. The optical thickness values, obtained from the measurements performed during the deposition process were as follows: 78 nm/78 nm for Al2O3/SiO2 and 78 nm/156 nm/78 nm for Al2O3/HfO2/SiO2. The results were then checked by ellipsometric technique. Reflectance of the films depended on the substrate temperature during the deposition process. Starting from 240 nm to the beginning of visible region, the average reflectance of the trilayer system was below 1 % and for the bilayer, minima of the reflectance were equal to 1.6 %, 1.15 % and 0.8 % for deposition temperatures of 100 °C, 200 °C and 300 °C, respectively.

Reaction mechanism for oxygen evolution on RuO 2, IrO 2, and RuO 2@IrO 2 core-shell nanocatalysts

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

Ma, Zhong; Zhang, Yu; Liu, Shizhong

Iridium dioxide, IrO 2, is second to the most active RuO 2 catalyst for the oxygen evolution reaction (OER) in acid, and is used in proton exchange membrane water electrolyzers due to its high durability. In order to improve the activity of IrO 2-based catalysts, we prepared RuO 2@IrO 2 core-shell nanocatalysts using carbon-supported Ru as the template. At 1.48 V, the OER specific activity of RuO 2@IrO 2 is threefold that of IrO 2. While the activity volcano plots over wide range of materials have been reported, zooming into the top region to clarify the rate limiting steps ofmore » most active catalysts is important for further activity enhancement. Here, we verified theory-proposed sequential water dissociation pathway in which the O—O bond forms on a single metal site, not via coupling of two adsorbed intermediates, by fitting measured polarization curves using a kinetic equation with the free energies of adsorption and activation as the parameters. Consistent with theoretical calculations, we show that the OER activities of IrO 2 and RuO 2@IrO 2 are limited by the formation of O adsorbed phase, while the OOH formation on the adsorbed O limits the reaction rate on RuO 2.« less

Reaction mechanism for oxygen evolution on RuO 2, IrO 2, and RuO 2@IrO 2 core-shell nanocatalysts

DOE PAGES

Ma, Zhong; Zhang, Yu; Liu, Shizhong; ...

2017-10-28

Iridium dioxide, IrO 2, is second to the most active RuO 2 catalyst for the oxygen evolution reaction (OER) in acid, and is used in proton exchange membrane water electrolyzers due to its high durability. In order to improve the activity of IrO 2-based catalysts, we prepared RuO 2@IrO 2 core-shell nanocatalysts using carbon-supported Ru as the template. At 1.48 V, the OER specific activity of RuO 2@IrO 2 is threefold that of IrO 2. While the activity volcano plots over wide range of materials have been reported, zooming into the top region to clarify the rate limiting steps ofmore » most active catalysts is important for further activity enhancement. Here, we verified theory-proposed sequential water dissociation pathway in which the O—O bond forms on a single metal site, not via coupling of two adsorbed intermediates, by fitting measured polarization curves using a kinetic equation with the free energies of adsorption and activation as the parameters. Consistent with theoretical calculations, we show that the OER activities of IrO 2 and RuO 2@IrO 2 are limited by the formation of O adsorbed phase, while the OOH formation on the adsorbed O limits the reaction rate on RuO 2.« less

Net Community and Gross Photosynthetic Production Rates in the Eastern Tropical South Pacific, as Determined from O2/AR Ratios and Triple Oxygen Isotopic Composition of Dissolved O2

NASA Astrophysics Data System (ADS)

Prokopenko, M. G.; Yeung, L. Y.; Berelson, W.; Fleming, J.; Rollins, N.; Young, E. D.; Haskell, W. Z.; Hammond, D. E.; Capone, D. G.

2010-12-01

This study assesses the rates of ocean carbon production and its fate with respect to recycling or export in the Eastern Tropical South Pacific (ETSP). ETSP has been previously identified as a region where N2 fixation and denitrification may be spatially coupled; this is also a region of localized CO2 outgassing. Using an Equilibrated Inlet Mass Spectrometer (EIMS) system, we obtained continuous measurements of the biological O2 supersaturation in the mixed layer along the ship track encompassing a region bounded by 10-20° S and 80-100° W in January - March, 2010. Vertical profiles were also taken at selected stations and analyzed for dissolved O2/Ar ratios on EIMS and triple oxygen isotope composition (17O excess) on a multi-collector IRMS (Isotope Ratio Mass Spectrometer) at UCLA. Gas exchange rates were estimated using two approaches: the Rn-222 deficit method and the wind parameterization method, which utilized wind speeds extracted from ASCAT satellite database. Oxygen Net Community Production (O-NCP) rates calculated based on biological O2 supersaturation ranged from slightly negative to ~ 0.3 - 15 mmol/m2d, with higher rates along the northern part of the transect. Oxygen Gross Community Production (O-GPP) rates calculated from 17O excess were between 50 ± 20 and 200 ± 40 mmol/m2d, with higher rates observed along the northern cruise transect as well. Notably, the NCP/GPP ratios along the northern transect were higher by the factor of 2 to 3 than their southern counterparts. The O2/Ar-based NCP rates were comparable to POC flux measured with floating traps deployed at the southern stations, but exceeded by a factor of 5-10 the trap POC fluxes obtained at the northern stations. A one-dimensional box model has been constructed to quantify the magnitude of oxygen primary production below the mixed layer. The results of this work will be integrated with measurements of 15-N2 uptake that are in progress, to constrain the potential contribution of N2 fixation

Mesoporous CNT@TiO2-C nanocable with extremely durable high rate capability for lithium-ion battery anodes.

PubMed

Wang, Bin; Xin, Huolin; Li, Xiaodong; Cheng, Jianli; Yang, Guangcheng; Nie, Fude

2014-01-16

A well-designed nanostructure CNT@TiO2-C with fine anatase TiO2 particle (< 8 nm), good electronic conducting network (inner CNT core and outer carbon layer), and mesoporous structure was prepared by a simple and green one-pot hydrothermal reaction. The utilization of glucose in the hydrothermal process not only solves the interfacial incompatibility between CNTs and titanate sol and controls the nucleation and growth of TiO2 particles, but also introduces a uniform, glucose-derived, carbon-layer on the TiO2 particles. The nanosized TiO2 particle, high conducting network, and interconnected nanopores of the CNT@TiO2-C nanocable greatly improve its electrochemical performances, especially rate capability. The CNT@TiO2-C nanocables show remarkable rate capability with reversible charge capacity of 297, 240, 210,178 and 127 mAh g(-1) at 1C, 5C, 10C, 20C and 50C, respectively, as well as excellent high rate cycling stability with capacity retention of 87% after 2000 cycles at 50C.

Mesoporous CNT@TiO2-C Nanocable with Extremely Durable High Rate Capability for Lithium-Ion Battery Anodes

NASA Astrophysics Data System (ADS)

Wang, Bin; Xin, Huolin; Li, Xiaodong; Cheng, Jianli; Yang, Guangcheng; Nie, Fude

2014-01-01

A well-designed nanostructure CNT@TiO2-C with fine anatase TiO2 particle (< 8 nm), good electronic conducting network (inner CNT core and outer carbon layer), and mesoporous structure was prepared by a simple and green one-pot hydrothermal reaction. The utilization of glucose in the hydrothermal process not only solves the interfacial incompatibility between CNTs and titanate sol and controls the nucleation and growth of TiO2 particles, but also introduces a uniform, glucose-derived, carbon-layer on the TiO2 particles. The nanosized TiO2 particle, high conducting network, and interconnected nanopores of the CNT@TiO2-C nanocable greatly improve its electrochemical performances, especially rate capability. The CNT@TiO2-C nanocables show remarkable rate capability with reversible charge capacity of 297, 240, 210,178 and 127 mAh g-1 at 1C, 5C, 10C, 20C and 50C, respectively, as well as excellent high rate cycling stability with capacity retention of 87% after 2000 cycles at 50C.

Can Twitter be used to predict county excessive alcohol consumption rates?

PubMed Central

Ashford, Robert D.; Hemmons, Jessie; Summers, Dan; Hamilton, Casey

2018-01-01

Objectives The current study analyzes a large set of Twitter data from 1,384 US counties to determine whether excessive alcohol consumption rates can be predicted by the words being posted from each county. Methods Data from over 138 million county-level tweets were analyzed using predictive modeling, differential language analysis, and mediating language analysis. Results Twitter language data captures cross-sectional patterns of excessive alcohol consumption beyond that of sociodemographic factors (e.g. age, gender, race, income, education), and can be used to accurately predict rates of excessive alcohol consumption. Additionally, mediation analysis found that Twitter topics (e.g. ‘ready gettin leave’) can explain much of the variance associated between socioeconomics and excessive alcohol consumption. Conclusions Twitter data can be used to predict public health concerns such as excessive drinking. Using mediation analysis in conjunction with predictive modeling allows for a high portion of the variance associated with socioeconomic status to be explained. PMID:29617408

Quantitative real-time optical imaging of the tissue metabolic rate of oxygen consumption

NASA Astrophysics Data System (ADS)

Ghijsen, Michael; Lentsch, Griffin R.; Gioux, Sylvain; Brenner, Matthew; Durkin, Anthony J.; Choi, Bernard; Tromberg, Bruce J.

2018-03-01

The tissue metabolic rate of oxygen consumption (tMRO2) is a clinically relevant marker for a number of pathologies including cancer and arterial occlusive disease. We present and validate a noncontact method for quantitatively mapping tMRO2 over a wide, scalable field of view at 16 frames / s. We achieve this by developing a dual-wavelength, near-infrared coherent spatial frequency-domain imaging (cSFDI) system to calculate tissue optical properties (i.e., absorption, μa, and reduced scattering, μs‧, parameters) as well as the speckle flow index (SFI) at every pixel. Images of tissue oxy- and deoxyhemoglobin concentration ( [ HbO2 ] and [HHb]) are calculated from optical properties and combined with SFI to calculate tMRO2. We validate the system using a series of yeast-hemoglobin tissue-simulating phantoms and conduct in vivo tests in humans using arterial occlusions that demonstrate sensitivity to tissue metabolic oxygen debt and its repayment. Finally, we image the impact of cyanide exposure and toxicity reversal in an in vivo rabbit model showing clear instances of mitochondrial uncoupling and significantly diminished tMRO2. We conclude that dual-wavelength cSFDI provides rapid, quantitative, wide-field mapping of tMRO2 that can reveal unique spatial and temporal dynamics relevant to tissue pathology and viability.

Effect of H2O and CO2 on The Oxidation Behavior and Durability at High Temperature of ODS-FeCrAl

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

Dryepondt, Sebastien N; Rouaix-Vande Put, Aurelie; Pint, Bruce A

Cyclic oxidation testing was conducted on alloy MA956 and two different batches of alloy PM2000 at 1100 and 1200 C in different atmospheres rich in O2, H2O and CO2. Compare to 1h cycle in dry O2, exposure in air + 10 vol.% H2O resulted in an increase of the oxidation rate and a decrease of the time to breakaway for both alloys at 1200 C, and a faster consumption of Al in the MA956 alloy. 1h cyclic testing in 50%CO2/50%H2O+0.75% O2 had less of an impact on the oxidation rate but led to an increased formation of voids for alloymore » MA956, which had an impact on the alloy creep resistance. At 1100 C, exposure in 50%CO2/50%H2O resulted in significant oxide spallation compared with oxidation in air, but it was not the case when 0.75% O2 was added to the CO2/H2O mixture as a buffer. The control of impurities levels drastically improved the PM2000 oxidation resistance.« less

Effect of H2O and CO2 on The Oxidation Behavior and Durability at High Temperature of ODS-FeCrAl

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

Dryepondt, Sebastien N; Pint, Bruce A; Rouaix-Vande Put, Aurelie

Cyclic oxidation testing was conducted on alloy MA956 and two different batches of alloy PM2000 at 1100 and 1200 C in different atmospheres rich in O2, H2O and CO2. Compared to 1h cycles in dry O2, exposure in air+10 vol.% H2O resulted in an increase of the oxidation rate and a decrease of the time to breakaway for all alloys at 1200 C, and a faster consumption of Al in the MA956 alloy. One hour cyclic testing in 49.25%CO2+50%H2O+0.75% O2 had a smaller effect on the oxidation rate but led to increased formation of voids in alloy MA956, which hadmore » an impact on the alloy creep resistance. At 1100 C, exposure in 50%CO2+50%H2O resulted in significant oxide spallation compared with oxidation in air, but this was not the case when 0.75% O2 was added to the CO2/H2O mixture as a buffer. The control of impurity levels drastically improved the oxidation resistance of PM2000.« less

O2(b1Σg+) Quenching by O2, CO2, H2O, and N2 at Temperatures of 300-800 K.

PubMed

Zagidullin, M V; Khvatov, N A; Medvedkov, I A; Tolstov, G I; Mebel, A M; Heaven, M C; Azyazov, V N

2017-10-05

Rate constants for the removal of O 2 (b 1 Σ g + ) by collisions with O 2 , N 2 , CO 2 , and H 2 O have been determined over the temperature range from 297 to 800 K. O 2 (b 1 Σ g + ) was excited by pulses from a tunable dye laser, and the deactivation kinetics were followed by observing the temporal behavior of the b 1 Σ g + -X 3 Σ g - fluorescence. The removal rate constants for CO 2 , N 2 , and H 2 O were not strongly dependent on temperature and could be represented by the expressions k CO2 = (1.18 ± 0.05) × 10 -17 × T 1.5 × exp[Formula: see text], k N2 = (8 ± 0.3) × 10 -20 × T 1.5 × exp[Formula: see text], and k H2O = (1.27 ± 0.08) × 10 -16 × T 1.5 × exp[Formula: see text] cm 3 molecule -1 s -1 . Rate constants for O 2 (b 1 Σ g + ) removal by O 2 (X), being orders of magnitude lower, demonstrated a sharp increase with temperature, represented by the fitted expression k O2 = (7.4 ± 0.8) × 10 -17 × T 0.5 × exp[Formula: see text] cm 3 molecule -1 s -1 . All of the rate constants measured at room temperature were found to be in good agreement with previously reported values.

Evaluation of Maximal O[subscript 2] Uptake with Undergraduate Students at the University of La Reunion

ERIC Educational Resources Information Center

Tarnus, Evelyne; Catan, Aurelie; Verkindt, Chantal; Bourdon, Emmanuel

2011-01-01

The maximal rate of O[subscript 2] consumption (VO[subscript 2max]) constitutes one of the oldest fitness indexes established for the measure of cardiorespiratory fitness and aerobic performance. Procedures have been developed in which VO[subscript 2max]is estimated from physiological responses during submaximal exercise. Generally, VO[subscript…

Fast growth rate of epitaxial β-Ga2O3 by close coupled showerhead MOCVD

NASA Astrophysics Data System (ADS)

Alema, Fikadu; Hertog, Brian; Osinsky, Andrei; Mukhopadhyay, Partha; Toporkov, Mykyta; Schoenfeld, Winston V.

2017-10-01

We report on the growth of epitaxial β-Ga2O3 thin films on c-plane sapphire substrates using a close coupled showerhead MOCVD reactor. Ga(DPM)3 (DPM = dipivaloylmethanate), triethylgallium (TEGa) and trimethylgallium (TMGa) metal organic (MO) precursors were used as Ga sources and molecular oxygen was used for oxidation. Films grown from each of the Ga sources had high growth rates, with up to 10 μm/hr achieved using a TMGa precursor at a substrate temperature of 900 °C. As confirmed by X-ray diffraction, the films grown from each of the Ga sources were the monoclinic (2 bar 0 1) oriented β-Ga2O3 phase. The optical bandgap of the films was also estimated to be ∼4.9 eV. The fast growth rate of β-Ga2O3 thin films obtained using various Ga-precursors has been achieved due to the close couple showerhead design of the MOCVD reactor as well as the separate injection of oxygen and MO precursors, preventing the premature oxidation of the MO sources. These results suggest a pathway to overcoming the long-standing challenge of realizing fast growth rates for Ga2O3 using the MOCVD method.

Retrieval of O2(1Σ) and O2(1Δ) volume emission rates in the mesosphere and lower thermosphere using SCIAMACHY MLT limb scans

NASA Astrophysics Data System (ADS)

Zarboo, Amirmahdi; Bender, Stefan; Burrows, John P.; Orphal, Johannes; Sinnhuber, Miriam

2018-01-01

We present the retrieved volume emission rates (VERs) from the airglow of both the daytime and twilight O2(1Σ) band and O2(1Δ) band emissions in the mesosphere and lower thermosphere (MLT). The SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY (SCIAMACHY) onboard the European Space Agency Envisat satellite observes upwelling radiances in limb-viewing geometry during its special MLT mode over the range 50-150 km. In this study we use the limb observations in the visible (595-811 nm) and near-infrared (1200-1360 nm) bands. We have investigated the daily mean latitudinal distributions and the time series of the retrieved VER in the altitude range from 53 to 149 km. The maximal observed VERs of O2(1Δ) during daytime are typically 1 to 2 orders of magnitude larger than those of O2(1Σ). The latter peaks at around 90 km, whereas the O2(1Δ) emissivity decreases with altitude, with the largest values at the lower edge of the observations (about 53 km). The VER values in the upper mesosphere (above 80 km) are found to depend on the position of the sun, with pronounced high values occurring during summer for O2(1Δ). O2(1Σ) emissions show additional high values at polar latitudes during winter and spring. These additional high values are presumably related to the downwelling of atomic oxygen after large sudden stratospheric warmings (SSWs). Accurate measurements of the O2(1Σ) and O2(1Δ) airglow, provided that the mechanism of their production is understood, yield valuable information about both the chemistry and dynamics in the MLT. For example, they can be used to infer the amounts and distribution of ozone, solar heating rates, and temperature in the MLT.

Porous MoO2 nanowires as stable and high-rate negative electrodes for electrochemical capacitors.

PubMed

Zheng, Dezhou; Feng, Haobin; Zhang, Xiyue; He, Xinjun; Yu, Minghao; Lu, Xihong; Tong, Yexiang

2017-04-04

Free-standing porous MoO 2 nanowires with extraordinary capacitive performance are developed as high-performance electrodes for electrochemical capacitors. The as-obtained MoO 2 electrode exhibits a remarkable capacitance of 424.4 mF cm -2 with excellent electrochemical durability (no capacitance decay after 10 000 cycles at various scan rates).

The denitrification paradox: The role of O2 in sediment N2O production

NASA Astrophysics Data System (ADS)

Barnes, Jonathan; Upstill-Goddard, Robert C.

2018-01-01

We designed a novel laboratory sediment flux chamber in which we maintained the headspace O2 partial pressure at preselected values, allowing us to experimentally regulate "in-situ" O2 to evaluate its role in net N2O production by an intertidal estuarine sediment (Tyne, UK). In short-term (30 h) incubations with 10 L of overlying estuarine water (∼3 cm depth) and headspace O2 regulation (headspace: sediment/water ratio ∼9:1), net N2O production was highest at 1.2% O2 (sub-oxic; 32.3 nmol N2O m-2 d-1), an order of magnitude higher than at either 0.0% (anoxic; 2.5 N2O nmol m-2 d-1) or 20.85% (ambient; 2.3 nmol N2O m-2 d-1) O2. In a longer-term sealed incubation (∼490 h) without O2 control, time-dependent behaviour of N2O in the tank headspace was highly non-linear with time, showing distinct phases: (i) an initial period of no or little change in O2 or N2O up to ∼ 100 h; (ii) a quasi-linear, inverse correlation between O2 and N2O to ∼360 h, in which O2 declined to ∼2.1% and N2O rose to ∼7800 natm; (iii) over the following 50 h a slower O2 decline, to ∼1.1%, and a more rapid N2O increase, to ∼12000 natm; (iv) over the next 24 h a slowed O2 decline towards undetectable levels and a sharp fall in N2O to ∼4600 natm; (iv) a continued N2O decrease at zero O2, to ∼3000 natm by ∼ 490 h. These results show clearly that rapid N2O consumption (∼115 nmol m-2 d-1), presumably via heterotrophic denitrification (HD), occurs under fully anoxic conditions and therefore that N2O production, which was optimal for sub-oxic O2, results from other nitrogen transformation processes. In experiments in which we amended sediment overlying water to either 1 mM NH4+ or 1 mM NO3-, N2O production rates were 2-134 nmol N2O m-2 d-1 (NH4+ addition) and 0.4-2.2 nmol N2O m-2 d-1 (NO3- addition). We conclude that processes involving NH4+ oxidation (nitrifier nitrification; nitrifier denitrification; nitrification-coupled denitrification) are principally responsible for N2O

Stibiconite (Sb3O6OH), senarmontite (Sb2O3) and valentinite (Sb2O3): Dissolution rates at pH 2-11 and isoelectric points

NASA Astrophysics Data System (ADS)

Biver, M.; Shotyk, W.

2013-05-01

Batch reactor experiments were carried out in order to derive rate laws for the proton promoted dissolution of the main natural antimony oxide phases, namely stibiconite (idealized composition SbSb2O6OH), senarmontite (cubic Sb2O3) and (metastable) valentinite (orthorhombic Sb2O3) over the range 2 ⩽ pH ⩽ 11, under standard conditions and ionic strength I = 0.01 mol l-1. The rates of antimony release by stibiconite were r = (2.2 ± 0.2) × 10-9 a(H+)0.11±0.01 mol m-2 s-1 for 2.00 ⩽ pH ⩽ 4.74 and r = (4.3 ± 0.2) × 10-10 a(H+)-0.030±0.003 mol m-2 s-1 for 4.74 ⩽ pH ⩽ 10.54. The rates of dissolution of senarmontite were r = (5.3 ± 2.2) × 10-7 a(H+)0.54±0.05 mol m-2 s-1 for 2.00 ⩽ pH ⩽ 6.93 and r = (1.4 ± 0.3) × 10-14 a(H+)-0.53±0.07 mol m-2 s-1 for 6.93 ⩽ pH ⩽ 10.83. The rates of dissolution of valentinite were r = (6.3 ± 0.2) × 10-8 a(H+)0.052±0.003 mol m-2 s-1 for 1.97 ⩽ pH ⩽ 6.85. Above pH = 6.85, valentinite was found to dissolve at a constant rate of r = (2.79 ± 0.05) × 10-8 mol m-2 s-1. Activation energies were determined at selected pH values in the acidic and basic domain, over the temperature range 25-50 °C. The values for stibiconite are -10.6 ± 1.9 kJ mol-1 (pH = 2.00) and 53 ± 14 kJ mol-1 (pH = 8.7). For senarmontite, we found 46.6 ± 4.7 kJ mol-1 (pH = 3.0) and 68.1 ± 6.1 kJ mol-1 (pH = 9.9) and for valentinite 41.9 ± 1.1 kJ mol-1 (pH = 3.0) and 39.0 ± 4.6 kJ mol-1 (pH = 9.9). These activation energies are interpreted in the text. The solubility of stibiconite at 25 °C in the pH domain from 2 to 10 was determined; solubilities decrease from 452.0 μg l-1 (as Sb) at pH = 2.00 to 153.2 μg l-1 at pH = 7.55 and increase again in the basic region, up to 176.6 μg l-1 at pH = 9.92. A graphical synopsis of all the kinetic results, including those of stibnite (Sb2S3) from earlier work, is presented. This allows an easy comparison between the dissolution rates of stibnite and the minerals examined in the present work

Calculated rate constants for the reaction ClO + O yields Cl + O2 between 220 and 1000 deg K. [molecular trajectories and stratospheric ozone

NASA Technical Reports Server (NTRS)

Jaffee, R. L.

1978-01-01

Classical trajectory calculations are presented for the reaction ClO + O yields Cl + O2, a reaction which is an important step in the chlorine-catalyzed destruction of ozone which is thought to occur in the 220 and 1000 K. The calculated rate constant is 4.36 x 10 to the minus 11th power exp (-191/T)cu cm molecule (-1)s(-1) and its value at 300 K is 2.3 plus or minus 10 to the 11th power cu cm molecule (-1)s(-1), about a factor of 2 lower than recent experimental data. The empirical potential energy surface used in the calculations was constructed to fit experimental data for ClO, O2 and ClOO molecules. Other important features of this potential surface, such as the barrier to reaction, were varied systematically and calculations were performed for a range of conditions to determine the best theoretical rate constants. Results demonstrate the utility of classical trajectory methods for determining activation energies and other kinetic data for important atmospheric reactions.

Understanding Combustion of H2/O2 Gases inside Nanobubbles Generated by Water Electrolysis Using Reactive Molecular Dynamic Simulations.

PubMed

Jain, S; Qiao, L

2018-06-21

This work explored the mechanism of spontaneous combustion of hydrogen-oxygen mixtures inside nanobubbles (which were generated by water electrolysis) using reactive molecular dynamic simulations based on the first-principles derived reactive force field ReaxFF. The effects of surface-assisted dissociation of H 2 and O 2 gases that produced H and O radicals were examined. Additionally, the ignition outcome and species evolution as a function of the initial system pressure (or bubble size) were studied. A significant amount of hydrogen peroxide (H 2 O 2 ), 6-140 times water (H 2 O), was observed in the combustion products. This was attributed to the low-temperature (∼300 K) and high-pressure (2-80 atm) conditions at which the chemical reactions were taking place. In addition, the rate of consumption of H 2 and O 2 molecules was found to increase with an increase in added H and O radical concentrations and initial system pressure. The rate at which heat was being lost from the combustion chamber (nanobubbles) was also compared to the rate at which heat was being released from the chemical reactions. Only a slight rise in the reaction temperature was observed (∼68 K), signifying that, at such small scales, heat losses dominate. The resulting chemistry was quite different from macroscopic combustion, which usually takes place at a much higher temperatures of above 1000 K.

Thermal characteristics, Raman spectra, optical and structural properties of TiO2-Bi2O3-B2O3-TeO2 glasses

NASA Astrophysics Data System (ADS)

Gupta, Nupur; Khanna, Atul; Gonzàlez, Fernando; Iordanova, Reni

2017-05-01

Tellurite and borotellurite glasses containing Bi2O3 and TiO2 were prepared and structure-property correlations were carried out by density measurements, X-ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Raman and UV-visible spectroscopy. Titanium tellurite glasses require high melt-cooling rates and were fabricated by splat quenching. On adding B2O3, the glass forming ability (GFA) enhances, and glasses could be synthesized at lower quenching rates. The density of glasses shows a direct correlation with molecular mass of the constituents. UV-visible studies were used to determine the optical band gap and refractive index. Raman studies found that the co-ordination number of tellurium ions with oxygen (NTe-O) decreases with the increase in B2O3 as well as Bi2O3 content while, TiO2 produce only a small decrease in NTe-O, which explains the lower GFA of titanium tellurite glasses that do not contain Bi2O3 and B2O3. DSC studies show that the glass transition temperature (Tg) increases with B2O3 and TiO2 concentrations and that Tg correlates well with bond enthalpy of the metal oxides.

Ab initio thermal rate calculations of HO + HO = O(3P) + H2O reaction and isotopologues.

PubMed

Nguyen, Thanh Lam; Stanton, John F

2013-04-04

The forward and reverse reactions, HO + HO ⇌ O((3)P) + H2O, which play roles in both combustion and laboratory studies, were theoretically characterized with a master equation approach to compute thermal reaction rate constants at both the low and high pressure limits. Our ab initio k(T) results for the title reaction and two isotopic variants agree very well with experiments (within 15%) over a wide temperature range. The calculated reaction rate shows a distinctly non-Arrhenius behavior and a strong curvature consistent with the experiment. This characteristic behavior is due to effects of positive barrier height and quantum mechanical tunneling. Tunneling is very important and contributes more than 70% of total reaction rate at room temperature. A prereactive complex is also important in the overall reaction scheme.

Impact of the oxygen defects and the hydrogen concentration on the surface of tetragonal and monoclinic ZrO2 on the reduction rates of stearic acid on Ni/ZrO2.

PubMed

Foraita, Sebastian; Fulton, John L; Chase, Zizwe A; Vjunov, Aleksei; Xu, Pinghong; Baráth, Eszter; Camaioni, Donald M; Zhao, Chen; Lercher, Johannes A

2015-02-02

The role of the specific physicochemical properties of ZrO2 phases on Ni/ZrO2 has been explored with respect to the reduction of stearic acid. Conversion on pure m-ZrO2 is 1.3 times more active than on t-ZrO2 , whereas Ni/m-ZrO2 is three times more active than Ni/t-ZrO2 . Although the hydrodeoxygenation of stearic acid can be catalyzed solely by Ni, the synergistic interaction between Ni and the ZrO2 support causes the variations in the reaction rates. Adsorption of the carboxylic acid group on an oxygen vacancy of ZrO2 and the abstraction of the α-hydrogen atom with the elimination of the oxygen atom to produce a ketene is the key to enhance the overall rate. The hydrogenated intermediate 1-octadecanol is in turn decarbonylated to heptadecane with identical rates on all catalysts. Decarbonylation of 1-octadecanol is concluded to be limited by the competitive adsorption of reactants and intermediate. The substantially higher adsorption of propionic acid demonstrated by IR spectroscopy and the higher reactivity to O2 exchange reactions with the more active catalyst indicate that the higher concentration of active oxygen defects on m-ZrO2 compared to t-ZrO2 causes the higher activity of Ni/m-ZrO2 . © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Metabolically-Derived Human Ventilation Rates: A Revised Approach Based Upon Oxygen Consumption Rates (External Review Draft)

EPA Science Inventory

EPA has released a draft report entitled, Metabolically-Derived Human Ventilation Rates: A Revised Approach Based Upon Oxygen Consumption Rates, for independent external peer review and public comment. NCEA published the Exposure Factors Handbook in 1997. This comprehens...

Role of self-caught fish in total fish consumption rates for recreational fishermen: Average consumption for some species exceeds allowable intake.

PubMed

Burger, Joanna

2013-01-01

Studies of fish consumption focus on recreational or subsistence fishing, on awareness and adherence to advisories, consumption patterns, and contaminants in fish. Yet the general public obtains their fish from commercial sources. In this paper I examine fish consumption patterns of recreational fishermen in New Jersey to determine: 1) consumption rates for self-caught fish and for other fish, 2) meals consumed per year, 3) average meal size, and average daily intake of mercury, and 4) variations in these parameters for commonly-consumed fish, and different methods of computing intake. Over 300 people were interviewed at fishing sites and fishing clubs along the New Jersey shore. Consumption patterns of anglers varied by species of fish. From 2 to 90 % of the anglers ate the different fish species, and between 9 and 75 % gave fish away to family or friends. Self-caught fish made up 7 to 92 % of fish diets. On average, self-caught fish were eaten for only 2 to 6 months of the year, whereas other fish (commercial or restaurant) were eaten up to 10 months a year. Anglers consumed from 5 to 36 meals of different fish a year, which resulted in intake of mercury ranging from 0.01 to 0.22 ug/kg/day. Average intake of Mako shark, swordfish, and tuna (sushi, canned tuna, self-caught tuna) exceeded the U.S. Environmental Protection Agency's oral, chronic reference dose for mercury of 0.1 ug/kg/day. However, computing intake using consumption for the highest month results in average mercury intake exceeding the reference dose for striped bass and bluefish as well. These data, and the variability in consumption patterns, have implications for risk assessors, risk managers, and health professionals.

Role of self-caught fish in total fish consumption rates for recreational fishermen: Average consumption for some species exceeds allowable intake

PubMed Central

Burger, Joanna

2013-01-01

Studies of fish consumption focus on recreational or subsistence fishing, on awareness and adherence to advisories, consumption patterns, and contaminants in fish. Yet the general public obtains their fish from commercial sources. In this paper I examine fish consumption patterns of recreational fishermen in New Jersey to determine: 1) consumption rates for self-caught fish and for other fish, 2) meals consumed per year, 3) average meal size, and average daily intake of mercury, and 4) variations in these parameters for commonly-consumed fish, and different methods of computing intake. Over 300 people were interviewed at fishing sites and fishing clubs along the New Jersey shore. Consumption patterns of anglers varied by species of fish. From 2 to 90 % of the anglers ate the different fish species, and between 9 and 75 % gave fish away to family or friends. Self-caught fish made up 7 to 92 % of fish diets. On average, self-caught fish were eaten for only 2 to 6 months of the year, whereas other fish (commercial or restaurant) were eaten up to 10 months a year. Anglers consumed from 5 to 36 meals of different fish a year, which resulted in intake of mercury ranging from 0.01 to 0.22 ug/kg/day. Average intake of Mako shark, swordfish, and tuna (sushi, canned tuna, self-caught tuna) exceeded the U.S. Environmental Protection Agency’s oral, chronic reference dose for mercury of 0.1 ug/kg/day. However, computing intake using consumption for the highest month results in average mercury intake exceeding the reference dose for striped bass and bluefish as well. These data, and the variability in consumption patterns, have implications for risk assessors, risk managers, and health professionals. PMID:23914136

Music increases alcohol consumption rate in young females.

PubMed

Stafford, Lorenzo D; Dodd, Hannah

2013-10-01

Previous field research has shown that individuals consumed more alcohol and at a faster rate in environments paired with loud music. Theoretically, this effect has been linked to approach/avoidance accounts of how music influences arousal and mood, but no work has tested this experimentally. In the present study, female participants (n = 45) consumed an alcoholic (4% alcohol-by-volume) beverage in one of three contexts: slow tempo music, fast tempo music, or a no-music control. Results revealed that, compared with the control, the beverage was consumed fastest in the two music conditions. Interestingly, whereas arousal and negative mood declined in the control condition, this was not the case for either of the music conditions, suggesting a downregulation of alcohol effects. We additionally found evidence for music to disrupt sensory systems in that, counterintuitively, faster consumption was driven by increases in perceived alcohol strength, which, in turn, predicted lower breath alcohol level (BrAL). These findings suggest a unique interaction of music environment and psychoactive effects of alcohol itself on consumption rate. Because alcohol consumed at a faster rate induces greater intoxication, these findings have implications for applied and theoretical work. PsycINFO Database Record (c) 2013 APA, all rights reserved.

Using consumption rate to assess potential predators for biological control of white perch

USGS Publications Warehouse

Gosch, N.J.C.; Pope, K.L.

2011-01-01

Control of undesirable fishes is important in aquatic systems, and using predation as a tool for biological control is an attractive option to fishery biologists. However, determining the appropriate predators for biological control is critical for success. The objective of this study was to evaluate the utility of consumption rate as an index to determine the most effective predators for biological control of an invasive fish. Consumption rate values were calculated for nine potential predators that prey on white perch Morone americana in Branched Oak and Pawnee reservoirs, Nebraska. The consumption rate index provided a unique and insightful means of determining the potential effectiveness of each predator species in controlling white perch. Cumulative frequency distributions facilitated interpretation by providing a graphical presentation of consumption rates by all individuals within each predator species. Largemouth bass Micropterus salmoides, walleye Sander vitreus and sauger S. canadensis were the most efficient white perch predators in both reservoirs; however, previous attempts to increase biomass of these predators have failed suggesting that successful biological control is unlikely using existing predator species in these Nebraska reservoirs. ?? 2011 ONEMA.

Vertical Transport Rates in the Stratosphere in 1993 from Observations of CO2, N2O and CH4

NASA Technical Reports Server (NTRS)

Wofsy, Steven C.; Boering, Kristie A.; Daube, Bruce C., Jr.; McElroy, Michael B.; Loewenstein, Max; Podolske, James R.; Elkins, James W.; Dutton, Geoffrey S.; Fahey, David W.

1994-01-01

Measurements of CO2, N2O and CH4 are analyzed to define hemispheric average vertical exchange rates in the lower stratosphere from November 1992 to October 1993. Effective vertical diffusion coefficients were small in summer, less than or equal to 1 m(exp 2)/sec at altitudes below 25 km; values were similar near the tropopause in winter, but increased markedly with altitude. The analysis suggests possibly longer residence times for exhaust from stratospheric aircraft, and more efficient transport from 20 km to the middle stratosphere, than predicted by many current models. Seasonally-resolved measurements of stratospheric CO2 and N2O provide significant new constraints on rates for global-scale vertical transport.

Photogeneration of H2O2 in SPEEK/PVA aqueous polymer solutions.

PubMed

Little, Brian K; Lockhart, PaviElle; Slaten, B L; Mills, G

2013-05-23

Photolysis of air-saturated aqueous solutions containing sulphonated poly(ether etherketone) and poly(vinyl alcohol) results in the generation of hydrogen peroxide. Consumption of oxygen and H2O2 formation are initially concurrent processes with a quantum yield of peroxide generation of 0.02 in stirred or unstirred solutions within the range of 7 ≤ pH ≤ 9. The results are rationalized in terms of O2 reduction by photogenerated α-hydroxy radicals of the polymeric ketone in competition with radical-radical processes that consume the macromolecular reducing agents. Generation of H2O2 is controlled by the photochemical transformation that produces the polymer radicals, which is most efficient in neutral and slightly alkaline solutions. Quenching of the excited state of the polyketone by both H3O(+) and OH(-) affect the yields of the reducing macromolecular radicals and of H2O2. Deprotonation of the α-hydroxy polymeric radicals at pH > 9 accelerate their decay and contribute to suppressing the peroxide yields in basic solutions. Maxima in [H2O2] are observed when illuminations are performed with static systems, where O2 reduction is faster than diffusion of oxygen into the solutions. Under such conditions H2O2 can compete with O2 for the reducing radicals resulting in a consumption of the peroxide.

Per Capita Alcohol Consumption and Suicide Rates in the U.S., 1950-2002

ERIC Educational Resources Information Center

Landberg, Jonas

2009-01-01

The aim of this paper was to estimate how suicide rates in the United States are affected by changes in per capita consumption during the postwar period. The analysis included Annual suicide rates and per capita alcohol consumption data (total and beverage specific) for the period 1950-2002. Gender- and age-specific models were estimated using the…

Determination of the thermal rate coefficient, products, and branching ratios for the reaction of O/+/ /D-2/ with N2

NASA Technical Reports Server (NTRS)

Torr, D. G.; Torr, M. R.

1980-01-01

Atmosphere Explorer-C satellite measurements are used to determine rate coefficients (RCs) for the following reactions: O(+)(D-2) + N2 yields N2(+) + O (reaction 1), O(+)(D-2) + N2 yields O(+)(S-4) + N2 (reaction 2), and O(+)(D-2) + N2 yields NO(+) + N (reaction 3). Results show the RC for reaction 1 to be 1 (plus 1 or minus 0.5) x 10 to the -10th cu cm per sec, for reaction 2 to be 3 (plus 1 or minus 2) x 10 to the -11th cu cm per sec, and 3 to be less than 5.5 x 10 to the -11th cu cm per sec. It is also found that the reaction of O(+)(D-2) with N2 does not constitute a detectable source of NO(+) ions in the thermosphere.

Oxygen consumption rates by different oenological tannins in a model wine solution.

PubMed

Pascual, Olga; Vignault, Adeline; Gombau, Jordi; Navarro, Maria; Gómez-Alonso, Sergio; García-Romero, Esteban; Canals, Joan Miquel; Hermosín-Gutíerrez, Isidro; Teissedre, Pierre-Louis; Zamora, Fernando

2017-11-01

The kinetics of oxygen consumption by different oenological tannins were measured in a model wine solution using the non-invasive method based on luminiscence. The results indicate that the oxygen consumption rate follows second-order kinetics depending on tannin and oxygen concentrations. They also confirm that the oxygen consumption rate is influenced by temperature in accordance with Arrhenius law. The indications are that ellagitannins are the fastest oxygen consumers of the different oenological tannins, followed in decreasing order by quebracho tannins, skin tannins, seed tannins and finally gallotannins. This methodology can therefore be proposed as an index for determining the effectiveness of different commercial tannins in protecting wines against oxidation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Reduction of chromium (VI) on the hetero-system CuBi2O4/TiO2 under solar light

NASA Astrophysics Data System (ADS)

Lahmar, H.; Benamira, M.; Akika, F. Z.; Trari, M.

2017-11-01

The CuBi2O4/TiO2 heterojunction was tested with success for the photo-catalytic reduction of chromate ions under sunlight. CuBi2O4, prepared by nitrate process, was characterised photo-electrochemically. The oxide is stable against photo corrosion by consumption of holes in presence of oxalic acid. The light absorption promotes electrons in the conduction band of the sensitizer (CuBi2O4) with a very negative potential (-1.74 VSCE) to participate in the exchange of the electron with HCrO4-. The enhanced activity is due to electron injection of activated CuBi2O4 into TiO2-CB (-0.97 VSCE). The band gap of the semiconductor CuBi2O4 is 1.50 eV with a direct optical transition. This compound is a p-type semiconductor with a flat band potential of -0.39 VSCE and activation energy of 0.18 eV. The electrochemical impedance spectroscopy was undertaken to study the semiconductor/electrolyte interfacial phenomena. The photoactivity on the heterojunction is strongly enhanced. A remarkable performance is obtained in less than 4 h for a concentration of 30 mg in (Cr (VI)) at pH ∼ 4 and a dose of 1 mg/mL; a 98% reduction has been obtained. The kinetic of chromate photoreduction is well described by the Langmuir-Hinshelwood model. The chromate elimination obeys to a pseudo-first order kinetic with an apparent rate constant of 0.014 min-1.

Oxygen consumption and heart rate during repeated squatting exercises with or without whole-body vibration in the elderly.

PubMed

Avelar, Núbia Cp; Simão, Adriano P; Tossige-Gomes, Rosalina; Neves, Camila Dc; Mezencio, Bruno; Szmuchrowski, Leszek; Coimbra, Cândido C; Lacerda, Ana Cr

2011-12-01

Avelar, NCP, Simão, AP, Tossige-Gomes, R, Neves, CDC, Mezencio, B, Szmuchrowski, L, Coimbra, CC, and Lacerda, ACR. Oxygen consumption and heart rate during repeated squatting exercises with or without whole-body vibration in the elderly. J Strength Cond Res 25(12): 3495-3500, 2011-The aim of this study was to investigate whether vibration plus squatting would increase cardiovascular demand to the optimal exercise limits needed for the prescription of cardiovascular training. Oxygen consumption, measured breath by breath by a portable gas analysis system, and heart rate (HR), measured using an HR monitor, were evaluated in 18 elderly individuals, 15 women and 3 men with a mean age of 72 ± 6 years. These variables were measured simultaneously and at the same time points in each subject during rest and randomly during the performance of squatting exercises (8 series of 40 seconds, with 40 seconds of rest between series of performing squats in 3-second cycles with 10-60° of flexion, a total of 5 repetitions for 40 seconds) with or without vibration at a frequency of 40 Hz and amplitude of 4 mm, separated by at least 1 day. Associating whole-body vibration with squatting exercise resulted in an additional increase of around 20% in oxygen consumption and 7.5% in the HR recorded during exercise. However, during squatting exercise with vibration, the increase achieved in oxygen consumption was limited to around 2 metabolic equivalents, and mean HR represented around 56% of the predicted maximum HR for age. The results of this study show that, despite the fact that vibration increased oxygen consumption and HR during the performance of squatting exercise, the minimum standards of intensity for the prescription of physical exercise with the specific objective of improving cardiorespiratory fitness were not achieved. Therefore, a protocol such as that used in the study does not meet the threshold for cardiovascular training prescription.

Charge transfer between biogenic jarosite derived Fe3+and TiO2 enhances visible light photocatalytic activity of TiO2.

PubMed

Chowdhury, Mahabubur; Shoko, Sipiwe; Cummings, Fransciuos; Fester, Veruscha; Ojumu, Tunde Victor

2017-04-01

In this work, we have shown that mining waste derived Fe 3+ can be used to enhance the photocatalytic activity of TiO 2 . This will allow us to harness a waste product from the mines, and utilize it to enhance TiO 2 photocatalytic waste water treatment efficiency. An organic linker mediated route was utilized to create a composite of TiO 2 and biogenic jarosite. Evidence of FeOTi bonding in the TiO 2 /jarosite composite was apparent from the FTIR, EFTEM, EELS and ELNEFS analysis. The as prepared material showed enhanced photocatalytic activity compared to pristine TiO 2 , biogenic jarosite and mechanically mixed sample of jarosite and TiO 2 under both simulated and natural solar irradiation. The prepared material can reduce the electrical energy consumption by 4 times compared to pristine P25 for degradation of organic pollutant in water. The material also showed good recyclability. Results obtained from sedimentation experiments showed that the larger sized jarosite material provided the surface to TiO 2 nanoparticles, which increases the settling rate of the materials. This allowed simple and efficient recovery of the catalyst from the reaction system after completion of photocatalysis. Enhanced photocatalytic activity of the composite material was due to effective charge transfer between TiO 2 and jarosite derived Fe 3+ as was shown from the EELS and ELNEFS. Generation of OH was supported by photoluminesence (PL) experiments. Copyright © 2016. Published by Elsevier B.V.

Hierarchical porous NiCo2O4 nanowires for high-rate supercapacitors.

PubMed

Jiang, Hao; Ma, Jan; Li, Chunzhong

2012-05-11

We demonstrate a simple and scalable strategy for synthesizing hierarchical porous NiCo(2)O(4) nanowires which exhibit a high specific capacitance of 743 F g(-1) at 1 A g(-1) with excellent rate performance (78.6% capacity retention at 40 A g(-1)) and cycling stability (only 6.2% loss after 3000 cycles). This journal is © The Royal Society of Chemistry 2012

Microvascular oxygen consumption during sickle cell pain crisis.

PubMed

Rowley, Carol A; Ikeda, Allison K; Seidel, Miles; Anaebere, Tiffany C; Antalek, Matthew D; Seamon, Catherine; Conrey, Anna K; Mendelsohn, Laurel; Nichols, James; Gorbach, Alexander M; Kato, Gregory J; Ackerman, Hans

2014-05-15

Sickle cell disease is an inherited blood disorder characterized by chronic hemolytic anemia and episodic vaso-occlusive pain crises. Vaso-occlusion occurs when deoxygenated hemoglobin S polymerizes and erythrocytes sickle and adhere in the microvasculature, a process dependent on the concentration of hemoglobin S and the rate of deoxygenation, among other factors. We measured oxygen consumption in the thenar eminence during brachial artery occlusion in sickle cell patients and healthy individuals. Microvascular oxygen consumption was greater in sickle cell patients than in healthy individuals (median [interquartile range]; sickle cell: 0.91 [0.75-1.07] vs healthy: 0.75 [0.62-0.94] -ΔHbO2/min, P < .05) and was elevated further during acute pain crisis (crisis: 1.10 [0.78-1.30] vs recovered: 0.88 [0.76-1.03] -ΔHbO2/min, P < .05). Increased microvascular oxygen consumption during pain crisis could affect the local oxygen saturation of hemoglobin when oxygen delivery is limiting. Identifying the mechanisms of elevated oxygen consumption during pain crisis might lead to the development of new therapeutic interventions. This trial was registered at www.clinicaltrials.gov as #NCT01568710.

Highly Ordered TiO2 Microcones with High Rate Performance for Enhanced Lithium-Ion Storage.

PubMed

Rhee, Oonhee; Lee, Gibaek; Choi, Jinsub

2016-06-15

The perpendicularly oriented anatase TiO2 microcones for Li-ion battery application were synthesized via anodization of a Ti foil in aqueous HF + H3PO4 solution. The TiO2 microcones exhibited a high active surface area with a hollow core depending on applied voltage and reaction time, confirmed by SEM, XRD and TEM with EDS mapping. Li insertion/desertion into TiO2 microcones was evaluated for the first time in half-cell configuration in terms of various current density and long-term cyclability. The electrochemical experiments demonstrated that the as-prepared TiO2 microcones as anode material exhibited 3 times higher capacity as compared with TiO2 nanotubular structures, excellent rate performance (0.054 mAhcm(-2) even at 50 C) and reliable capacity retention during 500 cycles, which was attributed to facile diffusion of Li-ions induced in hollow anatase TiO2 microcones structure with multilayered nanofragment.

Isotopomer analysis of production and consumption mechanisms of N2O and CH4 in an advanced wastewater treatment system.

PubMed

Toyoda, Sakae; Suzuki, Yuuri; Hattori, Shohei; Yamada, Keita; Fujii, Ayako; Yoshida, Naohiro; Kouno, Rina; Murayama, Kouki; Shiomi, Hiroshi

2011-02-01

Wastewater treatment processes are believed to be anthropogenic sources of nitrous oxide (N(2)O) and methane (CH(4)). However, few studies have examined the mechanisms and controlling factors in production of these greenhouse gases in complex bacterial systems. To elucidate production and consumption mechanisms of N(2)O and CH(4) in microbial consortia during wastewater treatment and to characterize human waste sources, we measured their concentrations and isotopomer ratios (elemental isotope ratios and site-specific N isotope ratios in asymmetric molecules of NNO) in water and gas samples collected by an advanced treatment system in Tokyo. Although the estimated emissions of N(2)O and CH(4) from the system were found to be lower than those from the typical treatment systems reported before, water in biological reaction tanks was supersaturated with both gases. The concentration of N(2)O, produced mainly by nitrifier-denitrification as indicated by isotopomer ratios, was highest in the oxic tank (ca. 4000% saturation). The dissolved CH(4) concentration was highest in in-flow water (ca. 3000% saturation). It decreased gradually during treatment. Its carbon isotope ratio indicated that the decrease resulted from bacterial CH(4) oxidation and that microbial CH(4) production can occur in anaerobic and settling tanks.

Oxidation of dimethylselenide by δMnO2: oxidation product and factors affecting oxidation rate

USGS Publications Warehouse

Wang, Bronwen; Burau, Richard G.

1995-01-01

Volatile dimethylselenide (DMSe) was transformed to a nonvolatile Se compound in a ??-MnO2 suspension. The nonvolatile product was a single compound identified as dimethylselenoxide based on its mass spectra pattern. After 24 h, 100% of the DMSe added to a ??-MnO2 suspension was converted to nonpurgable Se as opposed to 20%, 18%, and 4% conversion for chromate, permanganate, and the filtrate from the suspension, respectively. Manganese was found in solution after reaction. These results imply that the reaction between manganese oxide and DMSe was a heterogeneous redox reaction involving solid phase ??-MnO2 and solution phase DMSe. Oxidation of DMSe to dimethylselenoxide [OSe(CH3)2] by a ??-MnO2 suspension appears to be first order with respect to ??-MnO2, to DMSe, and to hydrogen ion with an overall rate law of d[OSe(CH3)2 ]/dt = 95 M-2 min-1 [MnO2]1[DMSe]1[H+]1 for the MnO2 concentration range of 0.89 ?? 10-3 - 2.46 ?? 10-3 M, the DMSe concentration range of 3.9 ?? 10-7 - 15.5 ?? 10-7 M Se, and a hydrogen ion concentation range of 7.4 ?? 10-6 -9.5 ?? 10-8 M. A general surface site adsorption model is consistent with this rate equation if the uncharged |OMnOH is the surface adsorption site. DMSe acts as a Lewis base, and the manganese oxide surface acts as a Lewis acid. DMSe adsorption to |OMnOH can be viewed as a Lewis acid/ base complex between the largely p orbitals of the DMSe lone pair and the unoccupied eg orbitals on manganese oxide. For such a complex, frontier molecular orbital theory predicts electron transfer to occur via an inner-sphere complex between the DMSe and the manganese oxide. ?? 1995 American Chemical Society.

Succinate modulation of H2O2 release at NADH:ubiquinone oxidoreductase (Complex I) in brain mitochondria

PubMed Central

Zoccarato, Franco; Cavallini, Lucia; Bortolami, Silvia; Alexandre, Adolfo

2007-01-01

Complex I (NADH:ubiquinone oxidoreductase) is responsible for most of the mitochondrial H2O2 release, both during the oxidation of NAD-linked substrates and during succinate oxidation. The much faster succinate-dependent H2O2 production is ascribed to Complex I, being rotenone-sensitive. In the present paper, we report high-affinity succinate-supported H2O2 generation in the absence as well as in the presence of GM (glutamate/malate) (1 or 2 mM of each). In brain mitochondria, their only effect was to increase from 0.35 to 0.5 or to 0.65 mM the succinate concentration evoking the semi-maximal H2O2 release. GM are still oxidized in the presence of succinate, as indicated by the oxygen-consumption rates, which are intermediate between those of GM and of succinate alone when all substrates are present together. This effect is removed by rotenone, showing that it is not due to inhibition of succinate influx. Moreover, α-oxoglutarate production from GM, a measure of the activity of Complex I, is decreased, but not stopped, by succinate. It is concluded that succinate-induced H2O2 production occurs under conditions of regular downward electron flow in Complex I. Succinate concentration appears to modulate the rate of H2O2 release, probably by controlling the hydroquinone/quinone ratio. PMID:17477844

Kinetics of Reduction of CaO-FeO x -MgO-PbO-SiO2 Slags by CO-CO2 Gas Mixtures

NASA Astrophysics Data System (ADS)

Jahanshahi, Sharif; Wright, Steven

2017-08-01

Kinetics of the reaction of lead slags (PbO-CaO-SiO2-FeO x -MgO) with CO-CO2 gas mixtures was studied by monitoring the changes in the slag composition when a stream of CO-CO2 gas mixture was blown on the surface of thin layers of slags (3 to 10 mm) at temperatures in the range of 1453 K to 1593 K (1180 °C to 1320 °C). These measurements were carried out under conditions where mass transfer in the gas phase was not the rate-limiting step and the reduction rates were insensitive to factors affecting mass transfer in the slag phase. The results show simultaneous reduction of PbO and Fe2O3 in the slag. The measured specific rate of oxygen removal from the melts varied from about 1 × 10-6 to 4 × 10-5 mol O cm-2 s-1 and was strongly dependent on the slag chemistry and its oxidation state, partial pressure of CO in the reaction gas mixture, and temperature. The deduced apparent first-order rate constant increased with increasing iron oxide content, oxidation state of the slag, and temperature. The results indicate that under the employed experimental conditions, the rate of formation of CO2 at the gas-slag interface is likely to be the rate-limiting step.

Falloff curve and specific rate constants for the reaction NO/sub 2/ + NO/sub 2/ /r reversible/ N/sub 2/O/sub 4/

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

Borrell, P.; Cobos, C.J.; Luther, K.

1988-07-28

The rate of association of NO/sub 2/ to N/sub 2/O/sub 4/ was measured in N/sub 2/ at pressures from 1 to 207 bar. This way the reaction was observed in a large section of its falloff range. The relaxation of NO/sub 2//N/sub 2/O/sub 4/ mixtures was followed after laser flash photolysis of N/sub 2/O/sub 4/ at 248 nm. From the results the falloff curve was constructed, which gives the high- and low-pressure rate constants at 298 K (in cm/sup 3/ molecule/sup /minus/1/ s/sup /minus/1/): k/sub ass//sup infinity/ = (8.3 /plus minus/ 1.0) /times/ 10/sup /minus/13/ and k/sub ass//sup 0/ =more » (1.4 /plus minus/ 0.2) /times/ 10/sup /minus/33/(N/sub 2/). Earlier measurements believed to be in the low-pressure regime, have not been free from falloff effects. The low value of k/sup infinity/ was analyzed with the statistic adiabatic channel model, and specific rate constants, k(E,J), were calculated. They increase very steeply with energy just above the reaction threshold and go through maxima at low excess energies. These unusual effects are analyzed theoretically and the strong contributions are pointed out of the low-frequency vibrations which disappear during the dissociation of N/sub 2/O/sub 4/.« less

OH+ and H2O+: Probes of the Molecular Hydrogen Fraction and Cosmic-Ray Ionization Rate

NASA Astrophysics Data System (ADS)

Indriolo, Nick; Neufeld, D. A.; Gerin, M.; PRISMAS; WISH

2014-01-01

The fast ion-molecule chemistry that occurs in the interstellar medium (ISM) is initiated by cosmic-ray ionization of both atomic and molecular hydrogen. Species that are near the beginning of the network of interstellar chemistry such as the oxygen-bearing ions OH+ and H2O+ can be useful probes of the cosmic-ray ionization rate. This parameter is of particular interest as, to some extent, it controls the abundances of several molecules. Using observations of OH+ and H2O+ made with HIFI on board Herschel, we have inferred the cosmic-ray ionization rate of atomic hydrogen in multiple distinct clouds along 12 Galactic sight lines. These two molecules also allow us to determine the molecular hydrogen fraction (amount of hydrogen nuclei in H2 versus H) as OH+ and H2O+ abundances are dependent on the competition between dissociative recombination with electrons and hydrogen abstraction reactions involving H2. Our observations of OH+ and H2O+ indicate environments where H2 accounts for less than 10% of the available hydrogen nuclei, suggesting that these species primarily reside in the diffuse, atomic ISM. Average ionization rates in this gas are on the order of a few times 10-16 s-1, with most values in specific clouds above or below this average by a factor of 3 or so. This result is in good agreement with the most up-to-date determination of the distribution of cosmic-ray ionization rates in diffuse molecular clouds as inferred from observations of H3+.

Isotopomeric characterization of N2O produced, consumed, and emitted by automobiles.

PubMed

Toyoda, Sakae; Yamamoto, Sei-ichiro; Arai, Shinji; Nara, Hideki; Yoshida, Naohiro; Kashiwakura, Kiriko; Akiyama, Ken-ichi

2008-01-01

Fossil fuel combustion is the second largest anthropogenic source of nitrous oxide (N2O) after agriculture. The estimated global N2O flux from combustion sources, as well as from other sources, still has a large uncertainty. Herein, we characterize automobile sources using N2O isotopomer ratios (nitrogen and oxygen isotope ratios and intramolecular site preference of 15N, SP) to assess their contributions to total global sources and to deconvolute complex production/consumption processes during combustion and subsequent catalytic treatments of exhaust. Car exhaust gases were sampled under running and idling state, and N2O isotopomer ratios were measured by mass spectrometry. The N2O directly emitted from an engine of a vehicle running at constant velocity had almost constant isotopomer ratios (delta15Nbulk = -28.7 +/- 1.2 per thousand, delta18O = 28.6 +/- 3.3 per thousand, and SP = 4.2 +/- 0.8 per thousand) irrespective of the velocity. After passing through catalytic converters, the isotopomer ratios showed an increase which varied with the temperature and the aging of the catalysts. The increase suggests that both production and consumption of N2O occur on the catalyst and that their rates can be comparable. It was noticed that in the idling state, the N2O emitted from a brand new car has higher isotopomer ratios than that from used cars, which indicate that technical improvements in catalytic converters can reduce the N2O from mobile combustion sources. On average, the isotopomeric signatures of N2O finally emitted from automobiles are not sensitive to running/idling states or to aging of the catalysts. Characteristic average isotopomer ratios of N2O from automobile sources are estimated at -4.9 +/- 8.2 per thousand, 43.5 +/- 13.9 per thousand, and 12.2 +/- 9.1 per thousand for delta15Nbulk, delta18O, and SP, respectively.

Herschel Survey of Galactic OH+, H2O+, and H3O+: Probing the Molecular Hydrogen Fraction and Cosmic-Ray Ionization Rate

NASA Astrophysics Data System (ADS)

Indriolo, Nick; Neufeld, D. A.; Gerin, M.; Schilke, P.; Benz, A. O.; Winkel, B.; Menten, K. M.; Chambers, E. T.; Black, John H.; Bruderer, S.; Falgarone, E.; Godard, B.; Goicoechea, J. R.; Gupta, H.; Lis, D. C.; Ossenkopf, V.; Persson, C. M.; Sonnentrucker, P.; van der Tak, F. F. S.; van Dishoeck, E. F.; Wolfire, Mark G.; Wyrowski, F.

2015-02-01

In diffuse interstellar clouds the chemistry that leads to the formation of the oxygen-bearing ions OH+, H2O+, and H3O+ begins with the ionization of atomic hydrogen by cosmic rays, and continues through subsequent hydrogen abstraction reactions involving H2. Given these reaction pathways, the observed abundances of these molecules are useful in constraining both the total cosmic-ray ionization rate of atomic hydrogen (ζH) and molecular hydrogen fraction (f_H_2). We present observations targeting transitions of OH+, H2O+, and H3O+ made with the Herschel Space Observatory along 20 Galactic sight lines toward bright submillimeter continuum sources. Both OH+ and H2O+ are detected in absorption in multiple velocity components along every sight line, but H3O+ is only detected along 7 sight lines. From the molecular abundances we compute f_H_2 in multiple distinct components along each line of sight, and find a Gaussian distribution with mean and standard deviation 0.042 ± 0.018. This confirms previous findings that OH+ and H2O+ primarily reside in gas with low H2 fractions. We also infer ζH throughout our sample, and find a lognormal distribution with mean log (ζH) = -15.75 (ζH = 1.78 × 10-16 s-1) and standard deviation 0.29 for gas within the Galactic disk, but outside of the Galactic center. This is in good agreement with the mean and distribution of cosmic-ray ionization rates previously inferred from H_3^+ observations. Ionization rates in the Galactic center tend to be 10-100 times larger than found in the Galactic disk, also in accord with prior studies. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

An Experimental Study on What Controls the Ratios of 18O/16O and 17O/16O of O2 During Microbial Respiration

NASA Astrophysics Data System (ADS)

Stolper, D. A.; Ward, B. B.; Fischer, W. W.; Bender, M. L.

2015-12-01

18O/16O and 17O/16O ratios of atmospheric and dissolved oceanic O2 are key biogeochemical tracers of total photosynthesis and respiration on global to local length scales and glacial/interglacial time scales (Luz et al., 1999). Critical to the use of these ratios as biogeochemical tracers is knowledge of how they are affected by production, consumption, and transport of O2. We present new measurements of O2 respiration by E. coli and N. oceanus, an ammonia oxidizing bacterium, to test three assumptions of isotopically enabled models of the O2 cycle: (i) laboratory-measured respiratory 18O/16O isotope effects (18α) of microorganisms are constant under all experimental and natural conditions (e.g., temperature and growth rate); (ii) the respiratory 'mass law' relationship between 18O/16O and 17O/16O [17α = (18α)β] is universal; and (iii) 18α and β for aerobic ammonia and organic carbon oxidation are identical. For E. coli, we find that both 18α and β are variable. From 37°C to 15°C, 18α varies linearly with temperature from 17 to 14‰, and β varies linearly from 0.513 to 0.508. 18α and β do not appear to vary with growth rate (as tested using different carbon sources). Both 18α and β are lower than previous observations for bacteria: 18α = 17-20‰ (Kiddon et al., 1993) and β = 0.515 (Luz and Barkan, 2005). We were able to simulate the observed temperature dependence of 18α and β using a model of respiration with two isotopically discriminating steps: O2 binding to cytochrome bo oxidase (the respiratory enzyme) and reduction of O2 to H2O. Finally, initial results on N. oceanus suggest it has similar values for 18α and β as previously studied aerobic bacteria that consume organic carbon, providing the first support for assumption (iii). Based on these results, isotopically constrained biogeochemical models of O2 cycling may need to consider a temperature dependence for 18α and β for microbial respiration. For example, these results may

Electrochemically driven three-phase interlines into insulator compounds: electroreduction of solid SiO2 in molten CaCl2.

PubMed

Xiao, Wei; Jin, Xianbo; Deng, Yuan; Wang, Dihua; Hu, Xiaohong; Chen, George Z

2006-08-11

The electrochemical reduction of solid SiO2 (quartz) to Si is studied in molten CaCl2 at 1173 K. Experimental observations are compared and agree well with a novel penetration model in relation with electrochemistry at the dynamic conductor|insulator|electrolyte three-phase interlines. The findings show that the reduction of a cylindrical quartz pellet at certain potentials is mainly determined by the diffusion of the O(2-) ions and also the ohmic polarisation in the reduction-generated porous silicon layer. The reduction rate increases with the overpotential to a maximum after which the process is retarded, most likely due to precipitation of CaO in the reaction region (cathodic passivation). Data are reported on the reduction rate, current efficiency and energy consumption during the electroreduction of quartz under potentiostatic conditions. These theoretical and experimental findings form the basis for an in-depth discussion on the optimisation of the electroreduction method for the production of silicon.

Reflected shock tube studies of high-temperature rate constants for OH + CH4 --> CH3 + H2O and CH3 + NO2 --> CH3O + NO.

PubMed

Srinivasan, N K; Su, M-C; Sutherland, J W; Michael, J V

2005-03-10

The reflected shock tube technique with multipass absorption spectrometric detection of OH radicals at 308 nm has been used to study the reactions OH + CH(4) --> CH(3) + H(2)O and CH(3) + NO(2) --> CH(3)O + NO. Over the temperature range 840-2025 K, the rate constants for the first reaction can be represented by the Arrhenius expression k = (9.52 +/- 1.62) x 10(-11) exp[(-4134 +/- 222 K)/T] cm(3) molecule(-1) s(-1). Since this reaction is important in both combustion and atmospheric chemistry, there have been many prior investigations with a variety of techniques. The present results extend the temperature range by 500 K and have been combined with the most accurate earlier studies to derive an evaluation over the extended temperature range 195-2025 K. A three-parameter expression describes the rate behavior over this temperature range, k = (1.66 x 10(-18))T(2.182) exp[(-1231 K)/T] cm(3) molecule(-1) s(-1). Previous theoretical studies are discussed, and the present evaluation is compared to earlier theoretical estimates. Since CH(3) radicals are a product of the reaction and could cause secondary perturbations in rate constant determinations, the second reaction was studied by OH radical production from the fast reactions CH(3)O --> CH(2)O + H and H + NO(2) --> OH + NO. The measured rate constant is 2.26 x 10(-11) cm(3) molecule(-1) s(-1) and is not dependent on temperature from 233 to 1700 K within experimental error.

Oxygen uptake and local Po2 profiles in submerged larvae of phaeoxantha klugii (Coleoptera: Cicindelidae), as well as their metabolic rate in air.

PubMed

Zerm, M; Zinkler, D; Adis, J

2004-01-01

We studied whether oxygen uptake from the surrounding water might enhance survival in submerged third instar larvae of Phaeoxantha klugii, a tiger beetle from the central Amazonian floodplains. Local oxygen partial pressures (Po(2)) were measured with microcoaxial needle electrodes close to larvae submerged in initially air-saturated still water. The Po(2) profiles showed that the larvae exploit oxygen from the aquatic medium. Metabolism in the air of more or less resting larvae was determined by measuring the rate of CO(2) production (sV dot co2) with an infrared gas analyzer at 29 degrees C. The sV dot co2 was around 1.8 mu L g(-1) min(-1), equivalent to an oxygen consumption rate (sV dot o2) of 1.8-2.6 mu L g(-1) min(-1). Oxygen consumption (V dot o2) of individually submerged larvae measured in closed respiration chambers at 19-10.3 kPa Po(2) (initially air saturated, 29 degrees C) ranged between 0.05 and 0.2 mu L min(-1) and was not correlated with body mass. The sV dot o2 ranged between 0.1 and 0.4 mu L min(-1), that is, 4%-22% of the metabolic rate measured in air. Mean V dot o2 decreased with declining Po(2); however, some individuals showed contrary patterns. V dot o2 was additionally measured in dormant larvae, in larvae submerged for 1-2 d in open water or for 30-49 d within sediment, as well as in larvae exposed to anoxia before the measurements. The range of V dot o2 was similar in all groups, indicating that the larvae exploit oxygen from the water whenever available. Similar V dot o2 across the whole range of body mass investigated (0.31-0.76 g) suggests that oxygen uptake occurs by spiracular uptake. Assuming that larvae survive for some time at rates comparable to depressed metabolic rates reported for other insect species, it can be concluded that oxygen uptake from water can sustain aerobic metabolism even under quite severe hypoxia. It might therefore play an important role for survival during inundation periods.

Selective photocatalytic reduction of CO2 by H2O/H2 to CH4 and CH3OH over Cu-promoted In2O3/TiO2 nanocatalyst

NASA Astrophysics Data System (ADS)

Tahir, Muhammad; Tahir, Beenish; Saidina Amin, Nor Aishah; Alias, Hajar

2016-12-01

Photocatalytic CO2 reduction by H2O and/or H2 reductant to selective fuels over Cu-promoted In2O3/TiO2 photocatalyst has been investigated. The samples, prepared via a simple and direct sol-gel method, were characterized by XRD, SEM, TEM, XPS, N2 adsorption-desorption, UV-vis diffuse reflectance, Raman and PL spectroscopy. Cu and In loaded into TiO2, oxidized as Cu2+ and In3+, promoted efficient separation of photo-generated electron/hole pairs (e-/h+). The results indicate that the reduction rate of CO2 by H2O to CH4 approached to 181 μmol g-1 h-1 using 0.5% Cu-3% In2O3/TiO2 catalyst, a 1.53 fold higher than the production rate over the 3% In2O3/TiO2 and 5 times the amount produced over the pure TiO2. In addition, Cu was found to promote efficient production of CH3OH and yield rate reached to 68 μmol g-1 h-1 over 1% Cu-3% In2O3/TiO2 catalyst. This improvement was attributed to charge transfer property and suppressed recombination rate by Cu-metal. More importantly, H2 reductant was less favorable for CH4 production, yet a significant amount of CH4 and CH3OH were obtained using a mixture of H2O/H2 reductant. Therefore, Cu-loaded In2O3/TiO2 catalyst has shown to be capable for methanol production, whereas product selectivity was greatly depending on the amount of Cu-loading and the type of reductant. A photocatalytic reaction mechanism was proposed to understand the experimental results over the Cu-loaded In2O3/TiO2 catalyst.

A study on electrical conductivity of chemosynthetic Al 2O 3-2SiO 2 geoploymer materials

NASA Astrophysics Data System (ADS)

Cui, Xue-Min; Zheng, Guang-Jian; Han, Yao-Cong; Su, Feng; Zhou, Ji

Al 2O 3-2SiO 2 amorphous powders are synthesized by sol-gel method with tetraethoxysilane (TEOS) and aluminum nitrate (ANN) as the starting materials. The microstructure and phase structure of the powders are investigated by SEM and XRD analysis. Geopolymer materials samples are prepared by mechanically mixing stoichiometric amounts of calcined Al 2O 3-2SiO 2 powders and sodium silicate solutions to allow a mass ratio of Na 2O/Al 2O 3 = 0.4, 0.375, 0.35, 0.325, 0.288, 0.26, 0.23 or 0.2 separately, and finally to form a homogenous slurry at a fixed H 2O/Na 2O mole ratio = 11.7. The results show that the synthetic Al 2O 3-2SiO 2 powders have polycondensed property and their compressive strengthes are similar to that of nature metakaolin geopolymer materials. The results also show that the water consumption is not the main influencing factor on electrical conductivity of harden geopolymer materials but it can intensively affect the microstructure of geopolymer materials. In addition, the electrical conductivity of harden geopolymer sample is investigated, and the results show that the geopolymer materials have a high ionic electrical conductivity of about 1.5 × 10 -6 S cm -1 in air at room temperature.

Integrated measurements and modeling of CO2, CH4, and N2O fluxes using soil microsite frequency distributions

NASA Astrophysics Data System (ADS)

Davidson, Eric; Sihi, Debjani; Savage, Kathleen

2017-04-01

Soil fluxes of greenhouse gases (GHGs) play a significant role as biotic feedbacks to climate change. Production and consumption of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) are affected by complex interactions of temperature, moisture, and substrate supply, which are further complicated by spatial heterogeneity of the soil matrix. Models of belowground processes of these GHGs should be internally consistent with respect to the biophysical processes of gaseous production, consumption, and transport within the soil, including the contrasting effects of oxygen (O2) as either substrate or inhibitor. We installed automated chambers to simultaneously measure soil fluxes of CO2 (using LiCor-IRGA), CH4, and N2O (using Aerodyne quantum cascade laser) along soil moisture gradients at the Howland Forest in Maine, USA. Measured fluxes of these GHGs were used to develop and validate a merged model. While originally intended for aerobic respiration, the core structure of the Dual Arrhenius and Michaelis-Menten (DAMM) model was modified by adding M-M and Arrhenius functions for each GHG production and consumption process, and then using the same diffusion functions for each GHG and for O2. The area under a soil chamber was partitioned according to a log-normal probability distribution function, where only a small fraction of microsites had high available-C. The probability distribution of soil C leads to a simulated distribution of heterotrophic respiration, which translates to a distribution of O2 consumption among microsites. Linking microsite consumption of O2 with a diffusion model generates microsite concentrations of O2, which then determine the distribution of microsite production and consumption of CH4 and N2O, and subsequently their microsite concentrations using the same diffusion function. At many moisture values, there are some microsites of production and some of consumption for each gas, and the resulting simulated microsite concentrations of CH4

Formation Mechanism of CuAlO2 Prepared by Rapid Thermal Annealing of Al2O3/Cu2O/Sapphire Sandwich Structure

NASA Astrophysics Data System (ADS)

Shih, C. H.; Tseng, B. H.

Single-phase CuAlO2 films were successfully prepared by thin-film reaction of an Al2O3/Cu2O/sapphire sandwich structure. We found that the processing parameters, such as heating rate, holding temperature and annealing ambient, were all crucial to form CuAlO2 without second phases. Thermal annealing in pure oxygen ambient with a lower temperature ramp rate might result in the formation of CuAl2O4 in addition to CuAlO2, since part of Cu2O was oxidized to form CuO and caused the change in reaction path, i.e. CuO + Al2O3 → CuAl2O4. Typical annealing conditions successful to prepare single-phase CuAlO2 would be to heat the sample with a temperature rampt rate higher than 7.3 °C/sec and hold the temperature at 1100 °C in air ambient. The formation mechanism of CuAlO2 has also been studied by interrupting the reaction after a short period of annealing. TEM observations showed that the top Al2O3 layer with amorphous structure reacted immediately with Cu2O to form CuAlO2 in the early stage and then the remaining Cu2O reacted with the sapphire substrate.

Highly efficient and mild electrochemical mineralization of long-chain perfluorocarboxylic acids (C9-C10) by Ti/SnO2-Sb-Ce, Ti/SnO2-Sb/Ce-PbO2, and Ti/BDD electrodes.

PubMed

Lin, Hui; Niu, Junfeng; Xu, Jiale; Huang, Haiou; Li, Duo; Yue, Zhihan; Feng, Chenghong

2013-11-19

The electrochemical mineralization of environmentally persistent long-chain perfluorinated carboxylic acids (PFCAs), i.e., perfluorononanoic acid (C8F17COOH, PFNA) and perfluorodecanoic acid (C9F19COOH, PFDA) was investigated in aqueous solutions (0.25 mmol L(-1)) over Ti/SnO2-Sb-Ce (SnO2), Ti/SnO2-Sb/Ce-PbO2 (PbO2), and Ti/BDD (BDD) anodes under galvanostatic control at room temperature. Based on PFCA decay rate, total organic carbon (TOC) reduction, defluorination ratio, safety, and energy consumption, the performance of PbO2 electrode was comparable with that of BDD electrode. After 180 min electrolysis, the PFNA removals on BDD and PbO2 electrodes were 98.7 ± 0.4% and 97.1 ± 1.0%, respectively, while the corresponding PFDA removals were 96.0 ± 1.4% and 92.2 ± 1.9%. SnO2 electrode yielded lower PFCA removals and led to notable secondary pollution by Sb ions. The primary mineralization product, F(-), as well as trace amounts of intermediate PFCAs with shortened chain lengths, were detected in aqueous solution after electrolysis. On the basis of these results, a degradation mechanism including three potential routes is proposed: via formation of short-chain PFCAs by stepwise removal of CF2; direct mineralization to CO2 and HF; conversion to volatile fluorinated organic compounds. The results presented here demonstrate that electrochemical technique exhibits high efficiency in mineralizing PFNA and PFDA under mild conditions, and is promising for the treatment of long-chain PFCAs in wastewater.

Quenching of I(2P1/2) by NO2, N2O4, and N2O.

PubMed

Kabir, Md Humayun; Azyazov, Valeriy N; Heaven, Michael C

2007-10-11

Quenching of excited iodine atoms (I(5p5, 2P1/2)) by nitrogen oxides are processes of relevance to discharge-driven oxygen iodine lasers. Rate constants at ambient and elevated temperatures (293-380 K) for quenching of I(2P1/2) atoms by NO2, N2O4, and N2O have been measured using time-resolved I(2P1/2) --> I(2P3/2) 1315 nm emission. The excited atoms were generated by pulsed laser photodissociation of CF3I at 248 nm. The rate constants for I(2P1/2) quenching by NO2 and N2O were found to be independent of temperature over the range examined with average values of (2.9 +/- 0.3) x 10(-15) and (1.4 +/- 0.1) x 10(-15) cm3 s(-1), respectively. The rate constant for quenching of I(2P1/2) by N2O4 was found to be (3.5 +/- 0.5) x 10(-13) cm3 s(-1) at ambient temperature.

The Nucleation Rate of Single O2 Nanobubbles at Pt Nanoelectrodes.

PubMed

Soto, Álvaro Moreno; German, Sean R; Ren, Hang; van der Meer, Devaraj; Lohse, Detlef; Edwards, Martin A; White, Henry S

2018-06-13

Nanobubble nucleation is a problem that affects efficiency in electrocatalytic reactions since those bubbles can block the surface of the catalytic sites. In this article, we focus on the nucleation rate of O 2 nanobubbles resulting from the electrooxidation of H 2 O 2 at Pt disk nanoelectrodes. Bubbles form almost instantaneously when a critical peak current, i nb p , is applied, but for lower currents, bubble nucleation is a stochastic process in which the nucleation (induction) time, t ind , dramatically decreases as the applied current approaches i nb p , a consequence of the local supersaturation level, ζ, increasing at high currents. Here, by applying different currents below i nb p , nanobubbles take some time to nucleate and block the surface of the Pt electrode at which the reaction occurs, providing a means to measure the stochastic t ind . We study in detail the different conditions in which nanobubbles appear, concluding that the electrode surface needs to be preconditioned to achieve reproducible results. We also measure the activation energy for bubble nucleation, E a , which varies in the range from (6 to 30) kT, and assuming a spherically cap-shaped nanobubble nucleus, we determine the footprint diameter L = 8-15 nm, the contact angle to the electrode surface θ = 135-155°, and the number of O 2 molecules contained in the nucleus (50 to 900 molecules).

Embryogenesis and oxygen consumption in benthic egg clutches of a tropical clownfish, Amphiprion melanopus (Pomacentridae).

PubMed

Green, Bridget S

2004-05-01

Variation in size at hatching is common in demersal spawning organisms, suggesting that processes during embryonic development may be critical in determining growth and development. To examine critical periods during embryonic development in the demersal spawning reef fish Amphiprion melanopus, the rate of oxygen consumption within an egg clutch was compared to morphological changes in the embryos. Oxygen consumption was least on day 1 of development where organ differentiation had not begun (mean 1.73+/-0.34x10(-5) micromol O(2) egg(-1) s(-1)). Tail movement throughout the perivitelline fluid began on day 3 and is likely to assist in moving oxygen around the embryo, complementing diffusive transport. The appearance of haemoglobin in the blood corresponded to a peak in oxygen consumption on day 4, where the highest mean rate of oxygen consumption was recorded (6.73+/-0.82x10(-5) micromol O(2) egg(-1) s(-1)). This could be a critical period in development whereby risk of mortality is increased through increased embryo requirements at developmental thresholds.

Acute effects of black currant consumption on salivary flow rate and secretion rate of salivary immunoglobulin a in healthy smokers.

PubMed

Konić-Ristić, Aleksandra; Šavikin, Katarina; Zdunić, Gordana; Besu, Irina; Menković, Nebojša; Glibetić, Marija; Srdić-Rajić, Tatjana

2015-04-01

The role of saliva in maintaining oral health and homeostasis is based on its physicochemical properties and biological activities of its components, including salivary immunoglobulin A (IgA). Both salivary rates and immunological status of saliva are found to be compromised in smokers. The aim of this study was to investigate the acute time-dependent effect of smoking and black currant consumption on the salivary flow rate (SFR) and salivary IgA secretion rate (sIgA SR) in healthy smokers. SFR, sIgA levels in saliva, and sIgA SRs were determined in healthy smokers (n=8) at eight times of assessment within three consecutive interventions: at the baseline; 5, 30, and 60 min after smoking; 5, 30, and 60 min after black currant consumption (100 g), followed by smoking; and 5 min after black currant consumption. Smoking induced a significant delayed effect on SFR measured 60 min after smoking (P=.03), while black currant consumption preceding smoking prevented that effect. Salivary IgA concentrations and sIgA flow rates were not acutely influenced by smoking. Black currant consumption preceding smoking induced a significant decrease in sIgA concentrations 5 min after the intervention compared with the baseline (P=.046), with a further increasing trend, statistically significant, 60 min after the intervention (P=.025). Although smoking cessation is the most important strategy in the prevention of chronic diseases, the obtained results suggest that the influence of black currant consumption on negative effects of tobacco smoke on salivary flow and immunological status of saliva could partly reduce the smoking-associated risk on oral health.

Statistical modeling of the reactions Fe(+) + N2O → FeO(+) + N2 and FeO(+) + CO → Fe(+) + CO2.

PubMed

Ushakov, Vladimir G; Troe, Jürgen; Johnson, Ryan S; Guo, Hua; Ard, Shaun G; Melko, Joshua J; Shuman, Nicholas S; Viggiano, Albert A

2015-08-14

The rates of the reactions Fe(+) + N2O → FeO(+) + N2 and FeO(+) + CO → Fe(+) + CO2 are modeled by statistical rate theory accounting for energy- and angular momentum-specific rate constants for formation of the primary and secondary cationic adducts and their backward and forward reactions. The reactions are both suggested to proceed on sextet and quartet potential energy surfaces with efficient, but probably not complete, equilibration by spin-inversion of the populations of the sextet and quartet adducts. The influence of spin-inversion on the overall reaction rate is investigated. The differences of the two reaction rates mostly are due to different numbers of entrance states (atom + linear rotor or linear rotor + linear rotor, respectively). The reaction Fe(+) + N2O was studied either with (6)Fe(+) or with (4)Fe(+) reactants. Differences in the rate constants of (6)Fe(+) and (4)Fe(+) reacting with N2O are attributed to different contributions from electronically excited potential energy surfaces, such as they originate from the open-electronic shell reactants.

Stimulation of H(2)O(2) generation by calcium in brain mitochondria respiring on alpha-glycerophosphate.

PubMed

Tretter, Laszlo; Takacs, Katalin; Kövér, Kinga; Adam-Vizi, Vera

2007-11-15

It has been reported recently (Tretter et al., 2007b) that in isolated guinea pig brain mitochondria supported by alpha-glycerophosphate (alpha-GP) reactive oxygen species (ROS) are produced through the reverse electron transport (RET) in the respiratory chain and by alpha-glycerophosphate dehydrogenase (alpha-GPDH). We studied the effect of calcium on the generation of H(2)O(2) as measured by the Amplex Red fluorescent assay in this model. H(2)O(2) production in alpha-GP-supported mitochondria was increased significantly in the presence of 100, 250, and 500 nM Ca(2+), respectively. In addition, Ca(2+) enhanced the membrane potential, the rate of oxygen consumption, and the NAD(P)H autofluorescence in these mitochondria. Direct measurement of alpha-GPDH activity showed that Ca(2+) stimulated the enzyme by decreasing the Km for alpha-GP. In those mitochondria where RET was eliminated by the Complex I inhibitor rotenone (2 microM) or due to depolarization by ADP (1 mM), the rate of H(2)O(2) formation was smaller and the stimulation of H(2)O(2) generation by Ca(2+) was prevented partly, but the stimulatory effect of Ca(2+) was still significant. These data indicate that in alpha-GP-supported mitochondria activation of alpha-GPDH by Ca(2+) leads to an accelerated RET-mediated ROS generation as well as to a stimulated ROS production by alpha-GPDH.

11C-Acetate clearance as an index of oxygen consumption of the right myocardium in idiopathic pulmonary arterial hypertension: a validation study using 15O-labeled tracers and PET.

PubMed

Wong, Yeun Ying; Raijmakers, Pieter; van Campen, Jasmijn; van der Laarse, Willem J; Knaapen, Paul; Lubberink, Mark; Ruiter, Gerrina; Vonk Noordegraaf, Anton; Lammertsma, Adriaan A

2013-08-01

Idiopathic pulmonary arterial hypertension (IPAH) results in increased right ventricular (RV) workload and oxygen demand. It has been shown that myocardial oxygen consumption (MVO2) of the hypertrophied right ventricle of IPAH patients can be measured using PET and (15)O-labeled tracers. This method is, however, not very suitable for routine clinical practice. The purpose of the present study was to assess whether MVO2 can also be determined in the right ventricle of IPAH patients from the clearance of (11)C-acetate, a simple method that is in use for MVO2 measurements of the left myocardium. Seventeen of 26 IPAH patients performed the total PET study. Nine other patients were scanned only for (11)C-acetate. (15)O-H2O, (15)O-O2, and (15)O-CO scans were used to derive RV flow, oxygen extraction fraction, and blood volume, respectively, from which RV MVO2 was calculated. The rate of clearance determined by monoexponential curve fitting (K(mono)) and the efflux rate constant k2 were derived from the (11)C-acetate scan. The RV rate-pressure product was also determined by means of right heart catheterization, as an index of the RV MVO2, and was calculated as the product of systolic pulmonary artery pressure and heart rate. Both (11)C-acetate clearance rates, K(mono) (R(2) = 0.41, P = 0.006) and k2 (R(2) = 0.45, P = 0.003), correlated with RV MVO2. They also correlated with RV rate-pressure product (K(mono), R(2) = 0.41, P = 0.0005; k2, R(2) = 0.48, P < 0.0001). (11)C-acetate clearance rates correlated moderately with quantitative RV MVO2 measurements in IPAH. Therefore, (11)C-acetate PET can be used only as an index of RV oxidative metabolism in IPAH patients.

Study on O2-supplying characteristics of Azolla in Controlled Ecological Life Support System

NASA Astrophysics Data System (ADS)

Chen, Min; Deng, Sufang; Yang, Youquang; Huang, Yibing; Liu, Zhongzhu

Azolla has high growth and propagation rate, strong photosynthetic O2-releasing ability and rich nutrient value. It is able to be used as salad-type vegetable, and can also be cultured on wet bed in multi-layer condition. Hence, it possesses a potential functioning as providing O2, fresh vegetable and absorbing CO2 for Controlled Ecological Life Support System in space. In this study, we try to make clear the O2-providing characteristics of Azolla in controlled close chamber under manned condition in order to lay a foundation for Azolla as a biological component in the next ground simulated experiment and space application. A closed test cham-ber of Controlled Ecological Life Support System and Azolla wet-culturing devices were built to measure the changes of atmospheric O2-CO2 concentration inside chamber under "Azolla-fish -men" coexisting condition. The results showed that, the amount of O2 consumption is 80.49 83.07 ml/h per kilogram fish, the amount of CO2 emissions is 70.49 73.56 ml/(kg • h); O2 consumption of trial volunteers is 19.71 L/h, the volume of respiration release CO2 18.90 L/h .Artificial light intensity of Azolla wet culture under 70009000 Lx, people respiration and Azolla photosynthesis complemented each other, the atmospheric O2-CO2 concentration inside chamber maintained equilibration. Elevated atmospheric CO2 concentrations in close chamber have obvious effects on enhancing Azolla net photosynthesis efficiency. This shows that Azolla has strong photosynthetic O2-releasing ability, which equilibrates the O2-CO2 concentration inside chamber in favor of human survival, and then verifies the prospect of Azolla in space application.

Upper limits for the rate constant for the reaction Br + H2O2 yields HB2 + HO2

NASA Technical Reports Server (NTRS)

Leu, M.-T.

1980-01-01

Upper limits for the rate constant for the reaction Br + H2O2 yields HBr + HO2 have been measured over the temperature range 298 to 417 K in a discharge flow system using a mass spectrometer as a detector. Results are k sub 1 less than 1.5 x 10 to the -15th power cu cm/s at 298 K and k sub 1 less than 3.0 x 10 to the -15th power cu cm/s at 417 K, respectively. The implication to stratospheric chemistry is discussed.

Temperature-dependent rate coefficients and theoretical calculations for the OH+Cl2O reaction.

PubMed

Riffault, Véronique; Clark, Jared M; Hansen, Jaron C; Ravishankara, A R; Burkholder, James B

2010-12-17

Rate coefficients k for the OH+Cl(2)O reaction are measured as a function of temperature (230-370 K) and pressure by using pulsed laser photolysis to produce OH radicals and laser-induced fluorescence to monitor their loss under pseudo-first-order conditions in OH. The reaction rate coefficient is found to be independent of pressure, within the precision of our measurements at 30-100 Torr (He) and 100 Torr (N(2)). The rate coefficients obtained at 100 Torr (He) showed a negative temperature dependence with a weak non-Arrhenius behavior. A room-temperature rate coefficient of k(1)(297 K)=(7.5±1.1)×10(-12) cm(3) molecule(-1) s(-1) is obtained, where the quoted uncertainties are 2σ and include estimated systematic errors. Theoretical methods are used to examine OH···OCl(2) and OH···ClOCl adduct formation and the potential-energy surfaces leading to the HOCl+ClO (1a) and Cl+HOOCl (1d) products in reaction (1) at the hybrid density functional UMPW1K/6-311++G(2df,p) level of theory. The OH···OCl(2) and OH···ClOCl adducts are found to have binding energies of about 0.2 kcal mol(-1). The reaction is calculated to proceed through weak pre-reactive complexes. Transition-state energies for channels (1a) and (1d) are calculated to be about 1.4 and about 3.3 kcal mol(-1) above the energy of the reactants. The results from the present study are compared with previously reported rate coefficients, and the interpretation of the possible non-Arrhenius behavior is discussed.

Calculation of the rate constant for state-selected recombination of H+O2(v) as a function of temperature and pressure

NASA Astrophysics Data System (ADS)

Teitelbaum, Heshel; Caridade, Pedro J. S. B.; Varandas, António J. C.

2004-06-01

Classical trajectory calculations using the MERCURY/VENUS code have been carried out on the H+O2 reactive system using the DMBE-IV potential energy surface. The vibrational quantum number and the temperature were selected over the ranges v=0 to 15, and T=300 to 10 000 K, respectively. All other variables were averaged. Rate constants were determined for the energy transfer process, H+O2(v)-->H+O2(v''), for the bimolecular exchange process, H+O2(v)-->OH(v')+O, and for the dissociative process, H+O2(v)-->H+O+O. The dissociative process appears to be a mere extension of the process of transferring large amounts of energy. State-to-state rate constants are given for the exchange reaction, and they are in reasonable agreement with previous results, while the energy transfer and dissociative rate constants have never been reported previously. The lifetime distributions of the HO2 complex, calculated as a function of v and temperature, were used as a basis for determining the relative contributions of various vibrational states of O2 to the thermal rate coefficients for recombination at various pressures. This novel approach, based on the complex's ability to survive until it collides in a secondary process with an inert gas, is used here for the first time. Complete falloff curves for the recombination of H+O2 are also calculated over a wide range of temperatures and pressures. The combination of the two separate studies results in pressure- and temperature-dependent rate constants for H+O2(v)(+Ar)⇄HO2(+Ar). It is found that, unlike the exchange reaction, vibrational and rotational-translational energy are liabilities in promoting recombination.

Respiration Rates of Resproductively Active and Diapausing Boll Weevils

Treesearch

Terence L. Wagner; E.J. Villavaso

1999-01-01

Low metabolism is a primary index of diapause in insects. Thus. rates of oxygen (O2) consumption and carbon dioxide (CO2) production are lower in diapausing than reproductive insects. To test this hypothesis, a respirometer was used to examine the age-, sex-, and food-dependent respiration rates of reproductive and...

Predicting the Rate Constant of Electron Tunneling Reactions at the CdSe-TiO2 Interface.

PubMed

Hines, Douglas A; Forrest, Ryan P; Corcelli, Steven A; Kamat, Prashant V

2015-06-18

Current interest in quantum dot solar cells (QDSCs) motivates an understanding of the electron transfer dynamics at the quantum dot (QD)-metal oxide (MO) interface. Employing transient absorption spectroscopy, we have monitored the electron transfer rate (ket) at this interface as a function of the bridge molecules that link QDs to TiO2. Using mercaptoacetic acid, 3-mercaptopropionic acid, 8-mercaptooctanoic acid, and 16-mercaptohexadecanoic acid, we observe an exponential attenuation of ket with increasing linker length, and attribute this to the tunneling of the electron through the insulating linker molecule. We model the electron transfer reaction using both rectangular and trapezoidal barrier models that have been discussed in the literature. The one-electron reduction potential (equivalent to the lowest unoccupied molecular orbital) of each molecule as determined by cyclic voltammetry (CV) was used to estimate the effective barrier height presented by each ligand at the CdSe-TiO2 interface. The electron transfer rate (ket) calculated for each CdSe-ligand-TiO2 interface using both models showed the results in agreement with the experimentally determined trend. This demonstrates that electron transfer between CdSe and TiO2 can be viewed as electron tunneling through a layer of linking molecules and provides a useful method for predicting electron transfer rate constants.

An evaluation of the rate of absorption of solar radiation in the O2(X3Sigma-g - b1Sigma-g) transition

NASA Technical Reports Server (NTRS)

Mlynczak, Martin G.

1993-01-01

The rate at which molecular oxygen absorbs radiation in the O2(X3Sigma-g - b1Sigma-g) transition is calculated using a line-by-line radiative transfer model. This rate is critical to the determination of the population of the O2(b1Sigma-g) state required for studies of the O2(b1Sigma-g - X3Sigma-g) dayglow, the O2(a1Delta-g - X3Sigma-g) dayglow, and possibly the rates of oxidation of H2 and N2O. Previous evaluations of this rate (which is sometimes called the g-factor) have significantly overestimated its value. The rate is tabulated as a function of altitude, pressure, and solar zenith angle.

Hydrodesulfurization of dibenzothiophene (DBT) catalyzed by sulfided CoO-MoO/sub 3//. gamma. -Al/sub 2/O/sub 3/: the reaction kinetics

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

Broderick, D.H.; Gates, B.C.

1980-01-01

Rates of the two competing conversion routes of DBT, a model compound for components of heavy oils and coal liquids, i.e., aromatic ring hydrogenation followed by hydrodesulfurization of the tetra- and hexahydro-DBT intermediates to cyclohexylbenzene (the hydrogenation route) and direct DBT hydrodesulfurization to biphenyl (the hydrogenolysis route) were measured independently at 548/sup 0/, 573/sup 0/, and 598/sup 0/K and 178 atm over an in-situ desulfurized commercial CoO-MoO/sub 3//..gamma..-Al/sub 2/O/sub 3/ catalyst. The rate data were fitted to Langmuir-Hinshelwood equations derived by nonlinear least-squares regression analysis, and all the kinetic parameters were accurately estimated. The selectivity for the hydrogenolysis route canmore » be increased, and hence hydrogen consumption minimized, by increasing temperature, reducing hydrogen sulfide concentration in the system through recycle gas scrubbing, or by adding quinoline which acts as inhibitor of the hydrogenation route preferentially.« less

Method to control deposition rate instabilities—High power impulse magnetron sputtering deposition of TiO{sub 2}

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

Kossoy, Anna, E-mail: annaeden@hi.is, E-mail: anna.kossoy@gmail.com; Magnusson, Rögnvaldur L.; Tryggvason, Tryggvi K.

2015-03-15

The authors describe how changes in shutter state (open/closed) affect sputter plasma conditions and stability of the deposition rate of Ti and TiO{sub 2} films. The films were grown by high power impulse magnetron sputtering in pure Ar and in Ar/O{sub 2} mixture from a metallic Ti target. The shutter state was found to have an effect on the pulse waveform for both pure Ar and reactive sputtering of Ti also affecting stability of TiO{sub 2} deposition rate. When the shutter opened, the shape of pulse current changed from rectangular to peak-plateau and pulse energy decreased. The authors attribute itmore » to the change in plasma impedance and gas rarefaction originating in geometry change in front of the magnetron. TiO{sub 2} deposition rate was initially found to be high, 1.45 Å/s, and then dropped by ∼40% during the first 5 min, while for Ti the change was less obvious. Instability of deposition rate poses significant challenge for growing multilayer heterostructures. In this work, the authors suggest a way to overcome this by monitoring the integrated average energy involved in the deposition process. It is possible to calibrate and control the film thickness by monitoring the integrated pulse energy and end growth when desired integrated pulse energy level has been reached.« less

Dynamic shear-stress-enhanced rates of nutrient consumption in gas-liquid semi-continuous-flow suspensions

NASA Astrophysics Data System (ADS)

Belfiore, Laurence A.; Volpato, Fabio Z.; Paulino, Alexandre T.; Belfiore, Carol J.

2011-12-01

The primary objective of this investigation is to establish guidelines for generating significant mammalian cell density in suspension bioreactors when stress-sensitive kinetics enhance the rate of nutrient consumption. Ultra-low-frequency dynamic modulations of the impeller (i.e., 35104 Hz) introduce time-dependent oscillatory shear into this transient analysis of cell proliferation under semi-continuous creeping flow conditions. Greater nutrient consumption is predicted when the amplitude A of modulated impeller rotation increases, and stress-kinetic contributions to nutrient consumption rates increase linearly at higher modulation frequency via an application of fluctuation-dissipation response. Interphase mass transfer is required to replace dissolved oxygen as it is consumed by aerobic nutrient consumption in the liquid phase. The theory and predictions described herein could be important at small length scales in the creeping flow regime where viscous shear is significant at the interface between the nutrient medium and isolated cells in suspension. Two-dimensional flow around spherically shaped mammalian cells, suspended in a Newtonian culture medium, is analyzed to calculate the surface-averaged magnitude of the velocity gradient tensor and modify homogeneous rates of nutrient consumption that are stimulated by viscous shear, via the formalism of stress-kinetic reciprocal relations that obey Curie's theorem in non-equilibrium thermodynamics. Time constants for stress-free free and stress-sensitive stress nutrient consumption are defined and quantified to identify the threshold (i.e., stress,threshold) below which the effect of stress cannot be neglected in accurate predictions of bioreactor performance. Parametric studies reveal that the threshold time constant for stress-sensitive nutrient consumption stress,threshold decreases when the time constant for stress

[Impact of the decrease of nitrous oxide use on the consumption of halogenated agents].

PubMed

Laverdure, F; Gaudin, A; Bourgain, J-L

2013-11-01

Nitrous oxide (N2O) toxicity and its impact on pollution lead to restrict its use. A decrease of N2O consumption should increase the hypnotic inhaled consumption. This monocentric study estimated consumptions and costs of halogenated agents (HA) and N2O over 5 years when the N2O consumption was reduced. Retrospective from a computerized database. Between 2006 and 2010, 34,097 procedures were studied after two meetings exposing the risks of the N2O. At the end of anesthesia, consumptions of hypnotic agents (millilitres transmitted by the injectors and the blender) were archived in the database. The annual consumption of agents was obtained by adding the individual consumptions, then divided by the annual number of cases. The costs were given by the hospital pharmacy from invoices. N2O consumption per anesthesia constantly decreased during the study, from 75.1L by act to 22.7L. The sum of the annual consumptions of N2O and air did not change suggesting that total fresh gas flow remained stable. Between 2006 and 2010, the sevoflurane consumption by act increased by 25%, from 16.5 to 20.6mL, and desflurane consumption by 37%, from 46.1 to 63.1mL by patient. The costs of the administration of hypnotic agents remained stable. N2O consumption decrease had an impact on the consumption of HA. The cost reduction of the N2O was counterbalanced by the increase of halogenated vapor cost. The profit of the ecological impact of the reduction in N2O use could be quantified. Copyright © 2013 Société française d’anesthésie et de réanimation (Sfar). Published by Elsevier SAS. All rights reserved.

Microhabitat Effects on N2O Emissions from Floodplain Soils under Controlled Conditions

NASA Astrophysics Data System (ADS)

Ley, Martin; Lehmann, Moritz; Niklaus, Pascal; Frey, Beat; Kuhn, Thomas; Luster, Jörg

2015-04-01

Semi-terrestrial soils such as floodplain soils are considered to be potential hotspots of nitrous oxide (N2O) emissions. The quantitative assessment of N2O release from these hot spots under field conditions, and of the microbial pathways that underlie net N2O production (ammonium oxidation, nitrifier-denitrification, and denitrification) is challenging in the environment because of the high spatial and temporal variability. The production and consumption of N2O appears to be linked to the presence or absence of micro-niches, providing specific conditions that may be favorable to either of the microbial pathways that produce or consume N2O. The availability of oxygen, reactive organic carbon, and dissolved nitrogen substrates likely play key roles with regards to the net production of N2O. Previous field studies demonstrated, for example, that flooding can trigger "hot moments" of enhanced N2O emission through a close coupling of niches with high and low oxygen availabilities. Such microhabitat effects likely depend on soil aggregate formation, plant soil interactions in the rhizosphere and the degradation of organic matter accumulations. In order to assess how these factors can modulate N2O production and consumption under simulated flooding/drying conditions, we have set up a mesocosm experiment with model soils comprising various mixtures of N-rich floodplain soil aggregates (4000 - 250 µm representing large aggregates, or <250 µm representing small aggregates) and inert matrix material (glass beads of 150 - 250 µm size, or quartz sand of 2000 - 3200 µm size, respectively). Soils containing the different aggregate size groups were either planted with willow (Salix viminalis L.), mixed with leaf litter or left untreated. At several time points before, during and after a simulated flood event, we measure the net efflux rate of N2O. In addition, soil water content, redox potential as well as carbon and nitrogen substrate availability are monitored. In order to

Protein expression and oxygen consumption rate of early postmortem mitochondria relate to meat tenderness.

PubMed

Grabež, V; Kathri, M; Phung, V; Moe, K M; Slinde, E; Skaugen, M; Saarem, K; Egelandsdal, B

2015-04-01

Oxygen consumption rate (OCR) of muscle fibers from bovine semimembranosus muscle of 41 animals was investigated 3 to 4 h and 3 wk postmortem. Significant relations (P < 0.05) were found between OCR measurements and Warner-Bratzler shear force measurement. Muscles with high mitochondrial OCR after 3 to 4 h and low nonmitochondrial oxygen consumption gave more tender meat. Tender (22.92 ± 2.2 N/cm2) and tough (72.98 ± 7.2 N/cm2) meat samples (4 samples each), separated based on their OCR measurements, were selected for proteomic studies using mitochondria isolated approximately 2.5 h postmortem. Twenty-six differently expressed proteins (P < 0.05) were identified in tender meat and 19 in tough meat. In tender meat, the more prevalent antioxidant and chaperon enzymes may reduce reactive oxygen species and prolong oxygen removal by the electron transport system (ETS). Glycolytic, Krebs cycle, and ETS enzymes were also more abundant in tender meat

Kinetics and oxidative mechanism for H2O2-enhanced iron-mediated aeration (IMA) treatment of recalcitrant organic compounds in mature landfill leachate.

PubMed

Deng, Yang; Englehardt, James D

2009-09-30

A hydrogen peroxide (H(2)O(2))-enhanced iron (Fe(0))-mediated aeration (IMA) process has been recently demonstrated to effectively remove organic wastes from mature landfill leachate. In this paper, the kinetics and oxidative mechanisms of the enhanced IMA treatment were studied. Bench-scale full factorial tests were conducted in an orbital shaker reactor for treatment of a mature leachate with an initial chemical oxygen demand (COD) of 900-1200 mg/L. At the maximum aeration rate (8.3 mL air/min mL sample), process variables significantly influencing the rates of H(2)O(2) decay and COD removal were pH (3.0-8.0), initial H(2)O(2) doses (0.21-0.84 M), and Fe(0) surface area concentrations (0.06-0.30 m(2)/L). Empirical kinetic models were developed and verified for the degradation of H(2)O(2) and COD. High DO maintained by a high aeration rate slowed the H(2)O(2) self-decomposition, accelerated Fe(0) consumption, and enhanced the COD removal. In hydroxyl radical (OH*) scavenging tests, the rate of removal of glyoxylic acid (target compound) was not inhibited by the addition of para-chlorobenzoic acid (OH* scavenger) at pH 7.0-7.5, ruling out hydroxyl radical as the principal oxidant in neutral-weakly basic solution. These experimental results show that this enhanced IMA technology is a potential alternative for the treatment of high strength recalcitrant organic wastewaters.

Tropical rainforest methane consumption during the El Niño of 2015-16

NASA Astrophysics Data System (ADS)

Aronson, E. L.; Dierick, D.; Botthoff, J.; Swanson, A. C.; Allen, M. F.

2016-12-01

Tropical forests sequester up to 40% of the anthropogenic and natural carbon exchanged with the atmosphere. Even though soils are the largest pool of terrestrial carbon, relatively little is known about the methane consumption capacity of tropical forest soils. Under high water, low oxygen (anaerobic) conditions, carbon decomposed is respired as methane (CH4) by methanogen microorganisms. During dry seasons, deeper rainforest soils remain wet, but dry at the surface. Since molecule for molecule the global warming potential of CH4 is two orders of magnitude greater than CO2, the relative production and sequestration of CO2 versus CH4 in tropical rainforests has a large impact on global climate trends. In 2015-16, the globe experienced an unusually strong ENSO event, which impacted the tropics. Atypical ENSO climatic events such as this include drought in tropical forests of Central America. We hypothesized that ENSO controls much of the year-to-year variability in the global CH4 cycle, primarily by turning the tropical forest from a strong annual source for CH4 during the La Niña or normal rainy season, to a year-round sink for CH4 during El Niño events. Further, we hypothesized that during a strong El Niño event, the unusually dry conditions of the tropical rainy season lead to the methanotrophs in these soils consuming large amounts of CH4. In order to investigate these predictions, CH4 flux was measured in three campaigns in March, during peak ENSO impact, as well as May and July 2016, at the La Selva Biological Station, Costa Rica. Fluxes were measured in eight paired plots, each with four collars. The collars measure 20 cm diameter by 12 cm in length, inserted into the soil, with a collar height of around 8 cm, in February 2016, a month before the first field campaign. Air samples were injected into pre-evacuated exetainers, and analyzed by gas chromatograph within 72 h. We found an average CH4 sink of -0.018 mg m-2 h-1. This flux is roughly four times lower

Caffeine Consumption and Heart Rate and Blood Pressure Response to Regadenoson

PubMed Central

Bitar, Abbas; Mastouri, Ronald; Kreutz, Rolf P.

2015-01-01

Background Current guidelines recommend that caffeinated products should be avoided for at least 12 hours prior to regadenoson administration. We intended to examine the effect of caffeine consumption and of timing of last dose on hemodynamic effects after regadenoson administration for cardiac stress testing. Methods 332 subjects undergoing regadenoson stress testing were enrolled. Baseline characteristics, habits of coffee/caffeine exposure, baseline vital signs and change in heart rate, blood pressure, percent of maximal predicted heart rate, and percent change in heart rate were prospectively collected. Results Non-coffee drinkers (group 1) (73 subjects) and subjects who last drank coffee >24 hours (group 3) (139 subjects) prior to regadenoson did not demonstrate any difference in systolic blood pressure, heart rate change, maximal predicted heart rate and percent change in heart rate. Systolic blood pressure change (15.2±17.1 vs. 7.2±10.2 mmHg, p = 0.001), heart rate change (32.2±14 vs. 27.3±9.6 bpm, p = 0.038) and maximal predicted heart rate (65.5±15.6 vs. 60.7±8.6%, p = 0.038) were significantly higher in non-coffee drinkers (group 1) compared to those who drank coffee 12–24 hours prior (group 2) (108 subjects). Subjects who drank coffee >24 hours prior (group 3) exhibited higher systolic blood pressure change (13±15.8 vs. 7±10.2, p = 0.007), and heart rate change (32.1±15.3 vs. 27.3±9.6, p = 0.017) as compared to those who drank coffee 12–24 hours prior to testing (group 2). Conclusions Caffeine exposure 12–24 hours prior to regadenoson administration attenuates the vasoactive effects of regadenoson, as evidenced by a blunted rise in heart rate and systolic blood pressure. These results suggest that caffeine exposure within 24 hours may reduce the effects of regadenoson administered for vasodilatory cardiac stress testing. PMID:26098883

Access to Street Markets and Consumption of Fruits and Vegetables by Adolescents Living in São Paulo, Brazil

PubMed Central

de Aguiar, Breno Souza; Barrozo, Ligia Vizeu; Goldbaum, Moisés; Cesar, Chester Luiz Galvão; Alves, Maria Cecilia Goi Porto

2018-01-01

Food environment and income act as determinants of diet, and consequently, of the consumption of fruits and vegetables. The objective of this study is to investigate the association between fruit and vegetable consumption, income, and street market density in adolescents living in São Paulo, Brazil. Data from 521 adolescents (12 to 19 years) participating in the 2015 Health Survey of São Paulo were used. Buffers (500, 1000, and 1500 m) were drawn around the households and the street markets were counted in each zone. Multilevel logistic regression models were used to evaluate the association between fruit and vegetable consumption, income, and street market density. The main results showed that the presence of a street market in the zone closest to the households (500 m) was associated with higher consumption of fruits and vegetables (OR: 1.73; CI 95% 1.01–3.00). Higher family income was associated with a higher consumption of fruits and vegetables for models of 500 m buffer (OR: 2.56; CI 95% 1.47–4.45), 1000 m (OR: 2.30; CI 95% 1.33–3.96), and 1500 m (OR: 2.32; CI 95% 1.35–4.00). These results support the implementation of public policies that jointly consider income and the availability of street markets or healthy food environments. PMID:29538324

Carbon dioxide consumption of the microalga Scenedesmus obtusiusculus under transient inlet CO2 concentration variations.

PubMed

Cabello, Juan; Morales, Marcia; Revah, Sergio

2017-04-15

The extensive microalgae diversity offers considerable versatility for a wide range of biotechnological applications in environmental and production processes. Microalgal cultivation is based on CO 2 fixation via photosynthesis and, consequently, it is necessary to evaluate, in a short time and reliable way, the effect of the CO 2 gas concentration on the consumption rate and establish the tolerance range of different strains and the amount of inorganic carbon that can be incorporated into biomass in order to establish the potential for industrial scale application. Dynamic experiments allow calculating the short-term microalgal photosynthetic activity of strains in photobioreactors. In this paper, the effect of step-changes in CO 2 concentration fed to a 20L bubble column photobioreactor on the CO 2 consumption rate of Scenedesmus obtusiusculus was evaluated at different operation times. The highest apparent CO 2 consumption rate (336μmolm -2 s -1 and 5.6% of CO 2 ) was 6530mg CO2 g b -1 d -1 and it decreased to 222mg CO2 g b -1 d -1 when biomass concentration increased of 0.5 to 3.1g b L -1 and 5.6% of CO 2 was fed. For low CO 2 concentrations (<3.8%) the pH remained close to the optimal value (7.5 and 8). The CO 2 consumption rates show that S. obtusiusculus was not limited by CO 2 availability for concentrations above of 3.8%. The CO 2 mass balance showed that 90% of the C-CO 2 transferred was used for S. obtusiusculus growth. Copyright © 2017. Published by Elsevier B.V.

Estimates of fish consumption rates for consumers of bought and self-caught fish in Connecticut, Florida, Minnesota, and North Dakota.

PubMed

Moya, Jacqueline; Itkin, Cheryl; Selevan, Sherry G; Rogers, John W; Clickner, Robert P

2008-09-15

Fish consumption rates derived from national surveys may not accurately reflect consumption rates in a particular population such as recreational anglers. Many state and local health agencies in the U.S. have conducted area-specific surveys to study fish consumption patterns in local populations, assess exposure to environmental contaminants, or evaluate compliance with fish advisories. The U.S. Environmental Protection Agency (EPA) has analyzed the raw data from fish consumption surveys in Florida, Connecticut, Minnesota, and North Dakota for the purpose of deriving distributions of fish consumption rates and studying the variables that may be more predictive of high-end consumers. Distributions of fish consumption for different age cohorts, ethnic groups, socioeconomic statuses, types of fish (i.e., freshwater, marine, estuarine), and source of fish (i.e., store-bought versus self-caught) were derived. Consumption of fish and shellfish for those who consume both caught and bought fish is higher than those who reported eating only bought or only self-caught. Mean fish consumption per kilogram of body weight ranged from 0.11 g/kg-day to 2.3 g/kg-day. The highest values were observed in Florida for children 1<6 years of age. The Florida data show a statistically significant increase in the percentage of the population reporting fish and shellfish consumption with an increase in household income and education. This trend was not observed in the other states.

Rate coefficient for H + O2 + M = HO2 + M evaluated from shock tube measurements of induction times

NASA Technical Reports Server (NTRS)

Slack, M. W.

1977-01-01

Shock tube experiments measured hydrogen-air induction times near the second explosion limit. By matching these experimental results with numerically predicted induction times, the rate coefficient for the reaction H + O2 + M = HO2 + M was evaluated as k-sub 4,N2 = 3.3 (plus or minus .6) x 10 to the 15 cm to the 6th/sq mole/s.

Roles of free radicals in NO oxidation by Fenton system and the enhancement on NO oxidation and H2O2 utilization efficiency.

PubMed

Zhao, Haiqian; Dong, Ming; Wang, Zhonghua; Wang, Huaiyuan; Qi, Hanbing

2018-06-20

Low H 2 O 2 utilization efficiency is the main problem when Fenton system was used to oxidize NO in flue gas. To understand the behavior of the free radicals during NO oxidation process in Fenton system is crucial to solving this problem. The oxidation capacity of ·OH and HO 2 · on NO in Fenton system was compared and the useless consumption path of ·OH and HO 2 · that caused the low utilization efficiency of H 2 O 2 were studied. A method to enhance the oxidation ability and H 2 O 2 utilization efficiency by adding reducing additives in Fenton system was proposed. The results showed that both of ·OH and HO 2 · were active substances that oxidize NO. However, the oxidation ability of ·OH radicals was stronger. The vast majority of ·OH and HO 2 · was consumed by rapid reaction ·OH+HO 2 ·→H 2 O+O 2 , which was the primary reason for the low utilization efficiency of H 2 O 2 in Fenton system. Hydroxylamine hydrochloride and ascorbic acid could accelerate the conversion of Fe 3+ to Fe 2+ , thereby increase the generation rate of ·OH and decrease the generation rate of HO 2 ·. As a result, the oxidation ability and H 2 O 2 utilization efficiency were enhanced.

Relation of body weight and food consumption to metabolic rate of juvenile Japanese sea bass, Lateolabrax japonicus

NASA Astrophysics Data System (ADS)

Xian, Wei-Wei; Zhu, Xin-Hua

2000-12-01

The metabolic rate of Japanese sea bass, Lateolabrax japonicus (C & V), was estimated in laboratory at temperature 25.2±0.5°C. The fresh weight of the fish was 4.64 52.28 g (average of 17.81±0.33 g). The routine metabolism was related to body weight by the exponential equation: R r =14.966 W 0.74 ( r=0.934). The rate of feeding metabolism increased linearly with food consumption. Feeding metabolic rate was 1.8 2.4 times the routine metabolic rate.

Effects of N2O narcosis on the contraction and repayment of an oxygen debt

NASA Technical Reports Server (NTRS)

Schatte, C. L.; Hall, P.; Fitch, J. W.; Loader, J. E.

1974-01-01

The oxygen deficit, oxygen debt, and the difference between them were measured in five male and three female subjects during and after exercise while breathing either air or a normoxic mixture containing 33% N2O and nitrogen. With the exception of a higher respiratory quotient at rest in N2O, there were no statistically significant differences for oxygen consumption, carbon dioxide production, expired gas volume, heart rate or blood lactate while breathing N2O during rest, exercise, or recovery. An appreciably, but not statistically, greater mean oxygen deficit was found in N2O along with a significantly greater mean oxygen debt; deficit-debt difference was unaffected by N2O. It was speculated that N2O narcosis did not affect the ability to utilize oxygen but that the response to the greater oxygen need of exercise may have been slowed with perhaps a concomitant greater depletion of stored high energy compounds.

Synergistic effects of TiO2 and Cu2O in UV/TiO2/zeolite-based systems on photodegradation of bisphenol A.

PubMed

Kuo, Chao-Yin; Wu, Chung-Hsin; Lin, Han-Yu

2014-08-01

In this study, TiO2/zeolite (TZ)-based composite was utilized to degrade bisphenol A (BPA) under ultraviolet (UV) irradiation. The effects of the TiO2 and Cu2O doses in TZ and Cu2O/TiO2/zeolite (CTZ) on the rate of BPA removal were identified, respectively. The surface area of TZ declined as the TiO2 loading increased. The photodegradation rate (k) of BPA in the TZ and CTZ systems fitted pseudo-first-order kinetics. Under UV (365 nm) irradiation, the k values of TiO2 (20%)/zeolite (80%), TiO2 (40%)/zeolite (60%), TiO2 (60%)/zeolite (40%), and TiO2 (80%)/zeolite (20%) were 0.51, 0.55, 0.97, and 0.91 h-1, respectively. In the UV (365nm)/TiO2 (60%)/zeolite (40%) system, the k values of CTZ with 1%, 5%, 10%, 20%, and 30% Cu2O added were 1.50, 1.04, 1.15, 1.88, and 0.47h-1, respectively. The photocatalytic activity of TZ was enhanced by adding Cu2O. The optimal dosage of TiO2 in the TZ system was 60% and that of Cu20 in the CTZ system was 20%. p-Hydroxybenzaldehyde (p-HBA), p-hydroxyacetophenone (p-HAP), p-hydroxybenzoic acid (p-HBA acid) and hydroquinone (HQ) were intermediates ofBPA photodegradation in the UV/TZ system and the rates of degradation followed the order HQ > p - HBA acid > BPA > p - HAP > p - HBA.

First Measurements of Time-Dependent Nucleation as a Function of Composition in Na2O.2CaO.3SiO2 Glasses

NASA Technical Reports Server (NTRS)

Kelton, K. F.; Narayan, K. Lakshmi

1996-01-01

The first measurements in any system of the composition dependence of the time-dependent nucleation rate are presented Nucleation rates of the stoichiometric crystalline phase, Na2O.2CaO.3SiO2, from quenched glasses made with different SiO2 concentrations were determined as a function of temperature and glass composition. A strong compositional dependence of the nucleation rates and a weak dependence for the induction times are observed. Using measured values of the liquidus temperatures and growth velocities as a function of glass composition, these data are shown to be consistent with predictions from the classical theory of nucleation, assuming a composition-dependent interfacial energy.

Comparative quantification of oxygen release by wetland plants: electrode technique and oxygen consumption model.

PubMed

Wu, Haiming; Liu, Jufeng; Zhang, Jian; Li, Cong; Fan, Jinlin; Xu, Xiaoli

2014-01-01

Understanding oxygen release by plants is important to the design of constructed wetlands for wastewater treatment. Lab-scale systems planted with Phragmites australis were studied to evaluate the amount of oxygen release by plants using electrode techniques and oxygen consumption model. Oxygen release rate (0.14 g O2/m(2)/day) measured using electrode techniques was much lower than that (3.94-25.20 gO2/m(2)/day) calculated using the oxygen consumption model. The results revealed that oxygen release by plants was significantly influenced by the oxygen demand for the degradation of pollutants, and the oxygen release rate increased with the rising of the concentration of degradable materials in the solution. The summary of the methods in qualifying oxygen release by wetland plants demonstrated that variations existed among different measuring methods and even in the same measuring approach. The results would be helpful for understanding the contribution of plants in constructed wetlands toward actual wastewater treatment.

Non-enzymatic detection of glucose in fruits using TiO2-Mn3O4 hybrid nano interface

NASA Astrophysics Data System (ADS)

Jayanth Babu, K.; Sasya, Madhurantakam; Nesakumar, Noel; Shankar, Prabakaran; Gumpu, Manju Bhargavi; Ramachandra, Bhat Lakshmishri; Kulandaisamy, Arockia Jayalatha; Rayappan, John Bosco Balaguru

2017-08-01

Consumption of fruits leads to increase in glucose level in blood for diabetic patients, which in turn leads to peripheral, vascular, ocular complications and cardiac diseases. In this context, a non-enzymatic hybrid glucose biosensor was fabricated for the first time to detect glucose by immobilizing titanium oxide-manganese oxide (TiO2-Mn3O4) nanocomposite and chitosan membrane on to the surface of Pt working electrode (Pt/TiO2-Mn3O4/chitosan). TiO2-Mn3O4 nanocomposite catalyzed the oxidation of glucose to gluconolactone in the absence of glucose oxidase enzyme with high electron transfer rate, good biocompatibility and large surface coverage. Electrochemical measurements revealed the excellent sensing response of the developed biosensor towards glucose with a high sensitivity of 7.073 µA mM-1, linearity of 0.01-0.1 mM, low detection limit of 0.01 µM, reproducibility of 1.5% and stability of 98.8%. The electrochemical parameters estimated from the anodic process were subjected to linear regression models for the detection of unknown concentration of glucose in different fruit samples.

Rate and Selectivity Control in Thioether and Alkene Oxidation with H 2 O 2 over Phosphonate-Modified Niobium(V)-Silica Catalysts

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

Thornburg, Nicholas E.; Notestein, Justin M.

Supported metal oxide catalysts are versatile materials for liquid-phase oxidations, including alkene epoxidation and thioether sulfoxidation with H2O2. Periodic trends in H2O2 activation was recently demonstrated for alkene epoxidation, highlighting Nb-SiO2 as a more active and selective catalyst than Ti-SiO2. Three representative catalysts are studied consisting of NbV, TiIV, and ZrIV on silica, each made through a molecular precursor approach that yields highly dispersed oxide sites, for thioanisole oxidation by H2O2. Initial rates trend Nb>Ti>>Zr, as for epoxidation, and Nb outperforms Ti for a number of other thioethers. In contrast, selectivity to sulfoxide vs. sulfone trends Ti>Nb>>Zr at all conversions.more » Modifying the Nb-SiO2 catalyst with phenylphosphonic acid does not completely remove sulfoxidation reactivity, as it did for photooxidation and epoxidation, and results in an unusual material active for sulfoxidation but neither epoxidation nor overoxidation to the sulfone.« less

Consumption-based accounting of CO2 emissions

PubMed Central

Davis, Steven J.; Caldeira, Ken

2010-01-01

CO2 emissions from the burning of fossil fuels are the primary cause of global warming. Much attention has been focused on the CO2 directly emitted by each country, but relatively little attention has been paid to the amount of emissions associated with the consumption of goods and services in each country. Consumption-based accounting of CO2 emissions differs from traditional, production-based inventories because of imports and exports of goods and services that, either directly or indirectly, involve CO2 emissions. Here, using the latest available data, we present a global consumption-based CO2 emissions inventory and calculations of associated consumption-based energy and carbon intensities. We find that, in 2004, 23% of global CO2 emissions, or 6.2 gigatonnes CO2, were traded internationally, primarily as exports from China and other emerging markets to consumers in developed countries. In some wealthy countries, including Switzerland, Sweden, Austria, the United Kingdom, and France, >30% of consumption-based emissions were imported, with net imports to many Europeans of >4 tons CO2 per person in 2004. Net import of emissions to the United States in the same year was somewhat less: 10.8% of total consumption-based emissions and 2.4 tons CO2 per person. In contrast, 22.5% of the emissions produced in China in 2004 were exported, on net, to consumers elsewhere. Consumption-based accounting of CO2 emissions demonstrates the potential for international carbon leakage. Sharing responsibility for emissions among producers and consumers could facilitate international agreement on global climate policy that is now hindered by concerns over the regional and historical inequity of emissions. PMID:20212122

Quenching of I(2P1/2) by O3 and O(3P).

PubMed

Azyazov, Valeriy N; Antonov, Ivan O; Heaven, Michael C

2007-04-26

Oxygen-iodine lasers that utilize electrical or microwave discharges to produce singlet oxygen are currently being developed. The discharge generators differ from conventional chemical singlet oxygen generators in that they produce significant amounts of atomic oxygen. Post-discharge chemistry includes channels that lead to the formation of ozone. Consequently, removal of I(2P1/2) by O atoms and O3 may impact the efficiency of discharge driven iodine lasers. In the present study, we have measured the rate constants for quenching of I(2P1/2) by O(3P) atoms and O3 using pulsed laser photolysis techniques. The rate constant for quenching by O3, (1.8 +/- 0.4) x 10(-12) cm3 s-1, was found to be a factor of 5 smaller than the literature value. The rate constant for quenching by O(3P) was (1.2 +/- 0.2) x 10(-11) cm3 s-1.

Mechanisms of nitrous oxide (N2 O) formation and reduction in denitrifying biofilms.

PubMed

Sabba, Fabrizio; Picioreanu, Cristian; Nerenberg, Robert

2017-12-01

Nitrous oxide (N 2 O) is a potent greenhouse gas that can be formed in wastewater treatment processes by ammonium oxidizing and denitrifying microorganisms. While N 2 O emissions from suspended growth systems have been extensively studied, and some recent studies have addressed emissions from nitrifying biofilms, much less is known about N 2 O emissions from denitrifying biofilm processes. This research used modeling to evaluate the mechanisms of N 2 O formation and reduction in denitrifying biofilms. The kinetic model included formation and consumption of key denitrification species, including nitrate (NO3-), nitrite (NO2-), nitric oxide (NO), and N 2 O. The model showed that, in presence of excess of electron donor, denitrifying biofilms have two distinct layers of activity: an outer layer where there is net production of N 2 O and an inner layer where there is net consumption. The presence of oxygen (O 2 ) had an important effect on N 2 O emission from suspended growth systems, but a smaller effect on biofilm systems. The effects of NO3- and O 2 differed significantly based on the biofilm thickness. Overall, the effects of biofilm thickness and bulk substrate concentrations on N 2 O emissions are complex and not always intuitive. A key mechanism for denitrifying biofilms is the diffusion of N 2 O and other intermediates from one zone of the biofilm to another. This leads to zones of N 2 O formation or consumption transformations that would not exist in suspended growth systems. © 2017 Wiley Periodicals, Inc.

The moderating effect of stimulus attractiveness on the effect of alcohol consumption on attractiveness ratings.

PubMed

Chen, Xiong; Wang, Xiaoyu; Yang, Dong; Chen, Youguo

2014-01-01

To explore the enhancing effect of alcohol consumption on attractiveness ratings, in that few studies on the Beer Goggles effect control the stimuli attractiveness level and researchers have seldom considered extending the effect to stimuli other than faces. Male and female participants (n = 103) were randomly assigned to alcohol consumption or placebo groups. Both groups were asked to assess the attractiveness of two types of pictures (faces and landscapes) with three levels of attractiveness for each stimulus category (high, moderate and low). We found significant interactions between beverage type and attractiveness level. Attractiveness ratings for moderate- and low-attractiveness faces were significantly higher in the alcohol compared with placebo condition, while there was no significant difference for high-attractiveness stimuli between these two conditions. As for landscapes, only low-attractiveness stimuli were rated significantly higher in the alcohol condition. Whether or not alcohol consumption leads to an increase in attractiveness ratings depends on the initial attractiveness of the stimulus materials. Alcohol consumption tends to affect ratings for stimuli with relatively low attractiveness. Furthermore, this effect is not limited to faces; it extends to other types of stimuli like landscapes. © The Author 2014. Medical Council on Alcohol and Oxford University Press. All rights reserved.

Slowdown of N2O emissions from China's croplands

NASA Astrophysics Data System (ADS)

Zhou, F.; Shang, Z.; Ciais, P.; Piao, S.; Tian, H.; Saikawa, E.; Zaehle, S.; Del Grosso, S. J.; Galloway, J. N.

2016-12-01

To feed the increasing population, China has experienced a rapid agricultural development over past decades, accompanied by increased fertilizer consumptions in croplands, but the magnitude, trend, and causes of the associated nitrous oxide (N2O) emissions has remain unclear. The primary sources of this uncertainty are conflicting estimates of fertilizer consumption and emission factors, the latter being uncertain because of very few regional representativeness of the Nrate-flux relationships in China. Here we re-estimate China's N2O emissions from croplands using three different methods: flux upscaling technique, process-based models and atmospheric inversion, and also analyze the corresponding drivers using an attribution approach. The three methods produce similar estimates of N2O emissions in the range of 0.67 ± 0.08 to 0.62± 0.11 Tg nitrogen per year, which is 29% larger than the estimates by the Emission Database for Global Atmospheric Research (EDGAR) that is adopted by Intergovernmental Panel on Climate Change (IPCC) as the emission baseline and twofold larger than the latest Chinese national report submitted to the United Nations Framework Convention on Climate Change, but the revised trend slows down after 2005. Fertilizer N application per area is the dominant factor driving the increase in N2O emissions across most cropping regions from 1990 to 2004, but climate-induced change of emission factors has also controlled N2O flux from 2005 onwards. Our findings suggest that, as precipitation would increase in North China but decline in the South in future, EF will increasingly control China's agri. soil emissions of N2O, unless offset by larger reductions of fertilizer consumptions.

The kinetics of oxygen and SO2 consumption by red wines. What do they tell about oxidation mechanisms and about changes in wine composition?

PubMed

Carrascón, Vanesa; Vallverdú-Queralt, Anna; Meudec, Emmanuelle; Sommerer, Nicolas; Fernandez-Zurbano, Purificación; Ferreira, Vicente

2018-02-15

This work seeks to understand the kinetics of O 2 and SO 2 consumption of air-saturated red wine as a function of its chemical composition, and to describe the chemical changes suffered during the process in relation to the kinetics. Oxygen Consumption Rates (OCRs) are faster with higher copper and epigallocatechin contents and with higher absorbance at 620nm and slower with higher levels of gallic acid and catechin terminal units in tannins. Acetaldehyde Reactive Polyphenols (ARPs) may be key elements determining OCRs. It is confirmed that SO 2 is poorly consumed in the first saturation. Phenylalanine, methionine and maybe, cysteine, seem to be consumed instead. A low SO 2 consumption is favoured by low levels of SO 2 , by a low availability of free SO 2 caused by a high anthocyanin/tannin ratio, and by a polyphenolic profile poor in epigallocatechin and rich in catechin-rich tannins. Wines consuming SO 2 efficiently consume more epigallocatechin, prodelphinidins and procyanidins. Copyright © 2017 Elsevier Ltd. All rights reserved.

Beetroot juice supplementation reduces whole body oxygen consumption but does not improve indices of mitochondrial efficiency in human skeletal muscle.

PubMed

Whitfield, J; Ludzki, A; Heigenhauser, G J F; Senden, J M G; Verdijk, L B; van Loon, L J C; Spriet, L L; Holloway, G P

2016-01-15

Oral consumption of nitrate (NO3(-)) in beetroot juice has been shown to decrease the oxygen cost of submaximal exercise; however, the mechanism of action remains unresolved. We supplemented recreationally active males with beetroot juice to determine if this altered mitochondrial bioenergetics. Despite reduced submaximal exercise oxygen consumption, measures of mitochondrial coupling and respiratory efficiency were not altered in muscle. In contrast, rates of mitochondrial hydrogen peroxide (H2O2) emission were increased in the absence of markers of lipid or protein oxidative damage. These results suggest that improvements in mitochondrial oxidative metabolism are not the cause of beetroot juice-mediated improvements in whole body oxygen consumption. Ingestion of sodium nitrate (NO3(-)) simultaneously reduces whole body oxygen consumption (V̇O2) during submaximal exercise while improving mitochondrial efficiency, suggesting a causal link. Consumption of beetroot juice (BRJ) elicits similar decreases in V̇O2 but potential effects on the mitochondria remain unknown. Therefore we examined the effects of 7-day supplementation with BRJ (280 ml day(-1), ∼26 mmol NO3(-)) in young active males (n = 10) who had muscle biopsies taken before and after supplementation for assessments of mitochondrial bioenergetics. Subjects performed 20 min of cycling (10 min at 50% and 70% V̇O2 peak) 48 h before 'Pre' (baseline) and 'Post' (day 5 of supplementation) biopsies. Whole body V̇O2 decreased (P < 0.05) by ∼3% at 70% V̇O2 peak following supplementation. Mitochondrial respiration in permeabilized muscle fibres showed no change in leak respiration, the content of proteins associated with uncoupling (UCP3, ANT1, ANT2), maximal substrate-supported respiration, or ADP sensitivity (apparent Km). In addition, isolated subsarcolemmal and intermyofibrillar mitochondria showed unaltered assessments of mitochondrial efficiency, including ADP consumed/oxygen consumed (P/O ratio

Bioactivity of gel-glass powders in the CaO-SiO2 system: a comparison with ternary (CaO-P2O5-SiO2) and quaternary glasses (SiO2-CaO-P2O5-Na2O).

PubMed

Saravanapavan, Priya; Jones, Julian R; Pryce, Russell S; Hench, Larry L

2003-07-01

Bioactive glasses react chemically with body fluids in a manner that is compatible with the repair processes of the tissues. This results in the formation of an interfacial bond between the glasses and living tissue. Bioactive glasses also stimulate bone-cell proliferation. This behavior is dependent on the chemical composition as well as the surface texture of the glasses. It has been recently reported that gel-derived monolith specimens in the binary SiO2 - CaO are bioactive over a similar molar range of SiO2 content as the previously studied ternary CaO-P2O5-SiO2 system. In this report, the preparation and bioactivity of the binary gel-glass powder with 70 mol % SiO2 is discussed and its bioactivity is compared with the melt-derived 45S5 (quaternary) Bioglass and sol-gel-derived 58S (ternary) bioactive gel-glass compositions. Dissolution kinetic parameters K(1) and K(2) were also computed based on the silicon release for all glass powders. It was shown that the simple two-component SiO2-CaO gel-glass powder is bioactive with comparable dissolution rates as the clinically used melt-derived 45S5 Bioglass powder and extensively studied sol-gel-derived 58S gel-glass powder. Copyright 2003 Wiley Periodicals, Inc.

H2O2 space shuttle APU

NASA Technical Reports Server (NTRS)

1975-01-01

A cryogenic H2-O2 auxiliary power unit (APU) was developed and successfully demonstrated. It has potential application as a minimum weight alternate to the space shuttle baseline APU because of its (1) low specific propellant consumption and (2) heat sink capabilities that reduce the amount of expendable evaporants. A reference system was designed with the necessary heat exchangers, combustor, turbine-gearbox, valves, and electronic controls to provide 400 shp to two aircraft hydraulic pumps. Development testing was carried out first on the combustor and control valves. This was followed by development of the control subsystem including the controller, the hydrogen and oxygen control valves, the combustor, and a turbine simulator. The complete APU system was hot tested for 10 hr with ambient and cryogenic propellants. Demonstrated at 95 percent of design power was 2.25 lb/hp-hr. At 10 percent design power, specific propellant consumption was 4 lb/hp-hr with space simulated exhaust and 5.2 lb/hp-hr with ambient exhaust. A 10 percent specific propellant consumption improvement is possible with some seal modifications. It was demonstrated that APU power levels could be changed by several hundred horsepower in less than 100 msec without exceeding allowable turbine inlet temperatures or turbine speed.

Electrochemical performance of La2O3/Li2O/TiO2 nano-particle coated cathode material LiFePO4.

PubMed

Wang, Hong; Yang, Chi; Liu, Shu-Xin

2014-09-01

Cathode material, LiFePO4 was modified by coating with a thin layer of La2O3/Li2O/TiO2 nano-particles for improving its performance for lithium ion batteries. The morphology and structure of the modified cathode material were characterized by powder X-ray diffraction, scanning electron microcopy and AES. The performance of the battery with the modified cathode material, including cycling stability, C-rate discharge was examined. The results show that the battery composed of the coated cathode materials can discharge at a large current density and show stable cycling performance in the range from 2.5 to 4.0 V. The rate of Li ion diffusion increases in the battery with the La2O3/Li2O/TiO2-coated LiFePO4 as a cathode and the coating layer may acts as a faster ion conductor (La(2/3-x)Li(3x)TiO3).

Rate constant for the H˙ + H2O → ˙OH + H2 reaction at elevated temperatures measured by pulse radiolysis.

PubMed

Muroya, Y; Yamashita, S; Lertnaisat, P; Sanguanmith, S; Meesungnoen, J; Jay-Gerin, J-P; Katsumura, Y

2017-11-22

Maintaining the structural integrity of materials in nuclear power plants is an essential issue associated with safe operation. Hydrogen (H 2 ) addition or injection to coolants is a powerful technique that has been widely applied such that the reducing conditions in the coolant water avoid corrosion and stress corrosion cracking (SCC). Because the radiation-induced reaction of ˙OH + H 2 → H˙ + H 2 O plays a crucial role in these systems, the rate constant has been measured at operation temperatures of the reactors (285-300 °C) by pulse radiolysis, generating sufficient data for analysis. The reverse reaction H˙ + H 2 O → ˙OH + H 2 is negligibly slow at ambient temperature; however, it accelerates considerably quickly at elevated temperatures. Although the reverse reaction reduces the effectiveness of H 2 addition, reliable rate constants have not yet been measured. In this study, the rate constants have been determined in a temperature range of 250-350 °C by pulse radiolysis in an aqueous I - solution.

Reaction of N2O5 with H2O on carbonaceous surfaces

NASA Technical Reports Server (NTRS)

Brouwer, L.; Rossi, M. J.; Golden, D. M.

1986-01-01

The heterogeneous reaction of N2O5 with commercially available ground charcoal in the absence of H2O revealed a physisorption process (gamma = 0.003), together with a redox reaction generating mostly NO. Slow HNO3 formation was the result of the interaction of N2O5 with H2O that was still adsorbed after prolonged pumping at 0.0001 torr. In the presence of H2O, the same processes with gamma = 0.005 are observed. The redox reaction dominates in the early stages of the reaction, whereas the hydrolysis gains importance later at the expense of the redox reaction. The rate law for HNO3 generation was found to be d(HNO3)/dt = k(bi)(H2O)(N2O5) with k(bi), the effective bimolecular rate constants, for 10 mg of carbon being (1.6 + or - 0.3) x 10 to the -13th cu cm/s.

Graphene-Wrapped Anatase TiO2 Nanofibers as High-Rate and Long-Cycle-Life Anode Material for Sodium Ion Batteries

PubMed Central

Yeo, Yeolmae; Jung, Ji-Won; Park, Kyusung; Kim, Il-Doo

2015-01-01

Anatase TiO2 has been suggested as a potential sodium anode material, but the low electrical conductivity of TiO2 often limits the rate capability, resulting in poor electrochemical properties. To address this limitation, we propose graphene-wrapped anatase TiO2 nanofibers (rGO@TiO2 NFs) through an effective wrapping of reduced graphene oxide (rGO) sheets on electrospun TiO2 NFs. To provide strong electrostatic interaction between the graphene oxide (GO) sheets and the TiO2 NFs, poly(allylamine hydrochloride) (PAH) was used to induce a positively charged TiO2 surface by the immobilization of the -NH3+ group and to promote bonding with the negatively charged carboxylic acid (-COO−) and hydroxyl (-O−) groups on the GO. A sodium anode electrode using rGO@TiO2 NFs exhibited a significantly improved initial capacity of 217 mAh g−1, high capacity retention (85% after 200 cycles at 0.2C), and a high average Coulombic efficiency (99.7% from the second cycle to the 200th cycle), even at a 5C rate, compared to those of pristine TiO2 NFs. The improved electrochemical performances stem from highly conductive properties of the reduced GO which is effectively anchored to the TiO2 NFs. PMID:26355340

Constraints on global oceanic emissions of N2O from observations and models

NASA Astrophysics Data System (ADS)

Buitenhuis, Erik T.; Suntharalingam, Parvadha; Le Quéré, Corinne

2018-04-01

We estimate the global ocean N2O flux to the atmosphere and its confidence interval using a statistical method based on model perturbation simulations and their fit to a database of ΔpN2O (n = 6136). We evaluate two submodels of N2O production. The first submodel splits N2O production into oxic and hypoxic pathways following previous publications. The second submodel explicitly represents the redox transformations of N that lead to N2O production (nitrification and hypoxic denitrification) and N2O consumption (suboxic denitrification), and is presented here for the first time. We perturb both submodels by modifying the key parameters of the N2O cycling pathways (nitrification rates; NH4+ uptake; N2O yields under oxic, hypoxic and suboxic conditions) and determine a set of optimal model parameters by minimisation of a cost function against four databases of N cycle observations. Our estimate of the global oceanic N2O flux resulting from this cost function minimisation derived from observed and model ΔpN2O concentrations is 2.4 ± 0.8 and 2.5 ± 0.8 Tg N yr-1 for the two N2O submodels. These estimates suggest that the currently available observational data of surface ΔpN2O constrain the global N2O flux to a narrower range relative to the large range of results presented in the latest IPCC report.

Oxidation of CO by N/sub 2/O between 1076 and 1228 K: determination of the rate constant of the exchange reaction

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

Loirat, H.; Caralp, F.; Destriau, M.

New measurements of the rate constant of the direct reaction of CO with N/sub 2/O are reported with the principal purpose of removing some of the remaining discrepancies on its value. Experiments were performed at lower temperatures (1076-1228 K) and lower pressure (approx. 15 Torr) than those prevailing in most of previous works, by using a static reactor. It is shown that, under these experimental conditions, the reaction proceeds essentially according to the direct reaction CO + N/sub 2/O ..-->.. CO/sub 2/ + N/sub 2/ (1). The previously proposed wet mechanism is not significant under our experimental conditions. It hasmore » to be taken into account, however, to describe the observed production and consumption of molecular oxygen. The Arrhenius expression derived from these experiments is k/sub 1/ = 10/sup 14.4 +/- 0.3 exp(-(46 +- 2) kcal mol/sup -1/RT) cm/sup 3/ mol/sup -1/ s/sup -1/. A detailed analysis of the results shows that the uncertainties in side reactions do not greatly influence the value of k/sub 1/. A critical discussion of the data reported in the literature is presented. In spite of remaining uncertainties in the reaction mechanism, the present results, obtained in a low-temperature range, show that the low activation energy values of reaction 1, reported in several works performed at higher temperatures, are highly unlikely« less

Altitude Variation of the CO2(V2)-O Quenching Rate Coefficient in Mesosphere and Lower Thermosphere

NASA Technical Reports Server (NTRS)

Feofilov, A.; Kutepov, A.; She, C.; Smith, A. K.; Pesnell, W. D.; Goldberg, R. A.

2010-01-01

Among the processes governing the energy balance in the mesosphere and lower thermosphere (MLT), the quenching of CO2(v2) vibrational levels by collisions with oxygen atoms plays an important role. However, the k(CO2-O) values measured in the lab and retrieved from atmospheric measurements vary from 1.5 x 10(exp -12)cu cm/s through 9.0 x 10(exp -12)cu cm/s that requires further studying. In this work we used synergistic data from a ground based lidar and a satellite infrared radiometer to estimate k(CO2-O). We used the night- and daytime temperatures between 80 and 110 km measured by the Colorado State University narrow-band sodium (Na) lidar located at Fort Collins, Colorado (41 N, 255E) as ground truth of the SABER/TIMED nearly simultaneous ( +/-10 minutes) and common volume (within +/-1 degree in latitude, +/-2 degrees in longitude) observations. For each altitude in 80-110 km interval we estimate an 'optimal" value of k(CO2-O) needed to minimize the discrepancy between the simulated 15 micron CO2 radiance and that measured by the SABER/TIMED instrument. The k(CO2-O) obtained in this way varies in altitude from 3.5 x 10(exp -12)cu cm/s at 80 km to 5.2 x 10(exp -12)cu cm/s for altitudes above 95 km. We discuss this variation of the rate constant and its impact on temperature retrievals from 15 pm radiance measurements and on the energy budget of MLT.

The chemistry of bromine in the stratosphere: Influence of a new rate constant for the reaction BrO + HO2

NASA Technical Reports Server (NTRS)

Pirre, Michel; Marceau, Francois J.; Lebras, Georges; Maguin, Francoise; Poulet, Gille; Ramaroson, Radiela

1994-01-01

The impact of new laboratory data for the reaction BrO + HO2 yields HOBr + O2 in the depletion of global stratospheric ozone has been estimated using a one-dimensional photochemical model taking into account the heterogeneous reaction on sulphate aerosols which converts N2O5 into HNO3. Assuring an aerosol loading 2 times as large as the 'background' and a reaction probability of 0.1 for the above heterogeneous reaction, the 6 fold increase in the measured rate constant for the reaction of BrO with HO2 increases the computed depletion of global ozone produced by 20 ppt of total bromine from 2.01 percent to 2.36 percent. The use of the higher rate constant increases the HOBr mixing ratio and makes the bromine partitioning and the ozone depletion very sensitive to the branching ratio of the potential channel forming HBr in the BrO + HO2 reaction.

Investigating the solubility and cytocompatibility of CaO-Na2 O-SiO2 /TiO2 bioactive glasses.

PubMed

Wren, Anthony W; Coughlan, Aisling; Smith, Courtney M; Hudson, Sarah P; Laffir, Fathima R; Towler, Mark R

2015-02-01

This study aims to investigate the solubility of a series of titanium (TiO2 )-containing bioactive glasses and their subsequent effect on cell viability. Five glasses were synthesized in the composition range SiO2 -Na2 O-CaO with 5 mol % of increments TiO2 substituted for SiO2 . Glass solubility was investigated with respect to (1) exposed surface area, (2) particle size, (3) incubation time, and (4) compositional effects. Ion release profiles showed that sodium (Na(+) ) presented high release rates after 1 day and were unchanged between 7 and 14 days. Calcium (Ca(2+) ) release presented a significant change at each time period and was also composition dependent, where a reduction in Ca(2+) release is observed with an increase in TiO2 concentration. Silica (Si(4+) ) release did not present any clear trends while no titanium (Ti(4+) ) was released. Cell numbers were found to increase up to 44%, compared to the growing control population, with a reduction in particle size and with the inclusion of TiO2 in the glass composition. © 2014 Wiley Periodicals, Inc.