Effect of oxygen on dislocation multiplication in silicon crystals

NASA Astrophysics Data System (ADS)

Fukushima, Wataru; Harada, Hirofumi; Miyamura, Yoshiji; Imai, Masato; Nakano, Satoshi; Kakimoto, Koichi

2018-03-01

This paper aims to clarify the effect of oxygen on dislocation multiplication in silicon single crystals grown by the Czochralski and floating zone methods using numerical analysis. The analysis is based on the Alexander-Haasen-Sumino model and involves oxygen diffusion from the bulk to the dislocation cores during the annealing process in a furnace. The results show that after the annealing process, the dislocation density in silicon single crystals decreases as a function of oxygen concentration. This decrease can be explained by considering the unlocking stress caused by interstitial oxygen atoms. When the oxygen concentration is 7.5 × 1017 cm-3, the total stress is about 2 MPa and the unlocking stress is less than 1 MPa. As the oxygen concentration increases, the unlocking stress also increases; however, the dislocation velocity decreases.

Multimodal optical imaging of microvessel network convective oxygen transport dynamics.

PubMed

Dedeugd, Casey; Wankhede, Mamta; Sorg, Brian S

2009-04-01

Convective oxygen transport by microvessels depends on several parameters, including red blood cell flux and oxygen saturation. We demonstrate the use of intravital microscopy techniques to measure hemoglobin saturations, red blood cell fluxes and velocities, and microvessel cross-sectional areas in regions of microvascular networks containing multiple vessels. With these methods, data can be obtained at high spatial and temporal resolution and correlations between oxygen transport and hemodynamic parameters can be assessed. In vivo data are presented for a mouse mammary adenocarcinoma grown in a dorsal skinfold window chamber model.

Effects of nitrogen- and oxygen-containing functional groups of activated carbon nanotubes on the electrochemical performance in supercapacitors

NASA Astrophysics Data System (ADS)

Liu, Haiyan; Song, Huaihe; Chen, Xiaohong; Zhang, Su; Zhou, Jisheng; Ma, Zhaokun

2015-07-01

A kind of nitrogen- and oxygen-containing activated carbon nanotubes (ACNTs) has been prepared by carbonization and activation of polyaniline nanotubes obtained by rapidly mixed reaction. The ACNTs show oxygen content of 15.7% and nitrogen content of 2.97% (atomic ratio). The ACNTs perform high capacitance and good rate capability (327 F g-1 at the current density of 10 A g-1) when used as the electrode materials for supercapacitors. Hydrogen reduction has been further used to investigate the effects of surface functional groups on the electrochemical performance. The changes for both structural component and electrochemical performance reveal that the quinone oxygen, pyridinic nitrogen, and pyrrolic nitrogen of carbon have the most obvious influence on the capacitive property because of their pseudocapacitive contributions.

A NEW NON-AMBIGUOUS ANALYTICAL TECHNIQUE FOR THE IDENTIFICATION OF AEROSOL OXYGENATED COMPOUNDS

EPA Science Inventory

The most important organic products identified in the particle phase from field samples and from smog chamber experiments are polar oxygenated compounds containing one, two, three or more oxygenated functional groups (e.g. hydroxyl, carboxylic acid, ketone). Current procedures ...

Co-regulation of Primary Mouse Hepatocyte Viability and Function by Oxygen and Matrix

PubMed Central

Buck, Lorenna D.; Inman, S. Walker; Rusyn, Ivan; Griffith, Linda G.

2014-01-01

Although oxygen and extracellular matrix cues both influence differentiation state and metabolic function of primary rat and human hepatocytes, relatively little is known about how these factors together regulate behaviors of primary mouse hepatocytes in culture. To determine the effects of pericellular oxygen tension on hepatocellular function, we employed 2 methods of altering oxygen concentration in the local cellular microenvironment of cells cultured in the presence or absence of an extracellular matrix (Matrigel) supplement. By systematically altering medium depth and gas phase oxygen tension, we created multiple oxygen regimes (hypoxic, normoxic, and hyperoxic) and measured the local oxygen concentrations in the pericellular environment using custom-designed oxygen microprobes. From these measurements of oxygen concentrations, we derived values of oxygen consumption rates under a spectrum of environmental contexts, thus providing the first reported estimates of these values for primary mouse hepatocytes. Oxygen tension and matrix microenvironment were found to synergistically regulate hepatocellular survival and function as assessed using quantitative image analysis for cells stained with vital dyes, and assessment of secretion of albumin. Hepatocellular viability was affected only at strongly hypoxic conditions. Surprisingly, albumin secretion rates were greatest at a moderately supra-physiological oxygen concentration, and this effect was mitigated at still greater supra-physiological concentrations. Matrigel enhanced the effects of oxygen on retention of function. This study underscores the importance of carefully controlling cell density, medium depth and gas phase oxygen, as the effects of these parameters on local pericellular oxygen tension and subsequent hepatocellular function are profound. PMID:24222008

LakeMetabolizer: An R package for estimating lake metabolism from free-water oxygen using diverse statistical models

USGS Publications Warehouse

Winslow, Luke; Zwart, Jacob A.; Batt, Ryan D.; Dugan, Hilary; Woolway, R. Iestyn; Corman, Jessica; Hanson, Paul C.; Read, Jordan S.

2016-01-01

Metabolism is a fundamental process in ecosystems that crosses multiple scales of organization from individual organisms to whole ecosystems. To improve sharing and reuse of published metabolism models, we developed LakeMetabolizer, an R package for estimating lake metabolism from in situ time series of dissolved oxygen, water temperature, and, optionally, additional environmental variables. LakeMetabolizer implements 5 different metabolism models with diverse statistical underpinnings: bookkeeping, ordinary least squares, maximum likelihood, Kalman filter, and Bayesian. Each of these 5 metabolism models can be combined with 1 of 7 models for computing the coefficient of gas exchange across the air–water interface (k). LakeMetabolizer also features a variety of supporting functions that compute conversions and implement calculations commonly applied to raw data prior to estimating metabolism (e.g., oxygen saturation and optical conversion models). These tools have been organized into an R package that contains example data, example use-cases, and function documentation. The release package version is available on the Comprehensive R Archive Network (CRAN), and the full open-source GPL-licensed code is freely available for examination and extension online. With this unified, open-source, and freely available package, we hope to improve access and facilitate the application of metabolism in studies and management of lentic ecosystems.

Molecular simulation of CO2/CH4 adsorption in brown coal: Effect of oxygen-, nitrogen-, and sulfur-containing functional groups

NASA Astrophysics Data System (ADS)

Dang, Yong; Zhao, Lianming; Lu, Xiaoqing; Xu, Jing; Sang, Pengpeng; Guo, Sheng; Zhu, Houyu; Guo, Wenyue

2017-11-01

The CO2/CH4 adsorption behaviors in brown coal at the temperatures of 298, 313, and 373 K and in the pressure range of 0.005-10 MPa were investigated by molecular dynamics (MD), density functional theory (DFT), and grand canonical Monte Carlo (GCMC) simulations. The absolute adsorption isotherms of single-component CH4 and CO2 exhibit type-I Langmuir adsorption behavior showing a negative influence of temperature. For the binary CO2/CH4 mixture, brown coal shows super high selectivity of CO2 over CH4 at pressures below 0.2 MPa, which then decreases quickly and finally tends to be constant when the pressure increases. The high competitive adsorption of CO2 originates from the effects of (i) the large electrostatic contributions, (ii) the conducive micropore environment with pore sizes below 0.56 nm, and (iii) the stronger adsorption of CO2 with respect to CH4. These effects are strengthened by the high-density oxygen-containing, pyridine, and thiophene functional groups contained in brown coal, which provide abundant and strong adsorption sites for CO2, but show weaker affinity to CH4. Furthermore, the influence of various nitrogen- and sulfur-containing functional groups on the CO2 adsorption capacity was also investigated. The results indicate that the basicity of the oxygen- and nitrogen-containing groups has a large influence on the CO2 adsorption, while for the sulfur functional groups the determining factor is the polarity.

Experimental study of the thermal stability of materials in high temperature oxygen-containing media

NASA Technical Reports Server (NTRS)

Abaltusov, Y. Y.; Bagramyan, A. R.; Grishin, A. M.; Yukhvid, V. I.

1986-01-01

An experimental study is made of the interaction of several materials with a high temperature medium containing oxygen. The temperature of the surface was measured as a function of time. It is found that the higher the velocity of mass removal from the surface, the more effective is the material from the viewpoint of heat resistance.

Co-regulation of primary mouse hepatocyte viability and function by oxygen and matrix.

PubMed

Buck, Lorenna D; Inman, S Walker; Rusyn, Ivan; Griffith, Linda G

2014-05-01

Although oxygen and extracellular matrix cues both influence differentiation state and metabolic function of primary rat and human hepatocytes, relatively little is known about how these factors together regulate behaviors of primary mouse hepatocytes in culture. To determine the effects of pericellular oxygen tension on hepatocellular function, we employed two methods of altering oxygen concentration in the local cellular microenvironment of cells cultured in the presence or absence of an extracellular matrix (Matrigel) supplement. By systematically altering medium depth and gas phase oxygen tension, we created multiple oxygen regimes (hypoxic, normoxic, and hyperoxic) and measured the local oxygen concentrations in the pericellular environment using custom-designed oxygen microprobes. From these measurements of oxygen concentrations, we derived values of oxygen consumption rates under a spectrum of environmental contexts, thus providing the first reported estimates of these values for primary mouse hepatocytes. Oxygen tension and matrix microenvironment were found to synergistically regulate hepatocellular survival and function as assessed using quantitative image analysis for cells stained with vital dyes, and assessment of secretion of albumin. Hepatocellular viability was affected only at strongly hypoxic conditions. Surprisingly, albumin secretion rates were greatest at a moderately supra-physiological oxygen concentration, and this effect was mitigated at still greater supra-physiological concentrations. Matrigel enhanced the effects of oxygen on retention of function. This study underscores the importance of carefully controlling cell density, medium depth, and gas phase oxygen, as the effects of these parameters on local pericellular oxygen tension and subsequent hepatocellular function are profound. © 2014 Wiley Periodicals, Inc.

New iron-sulfur clusters help hydrogenases tolerate oxygen.

PubMed

Grubel, Katarzyna; Holland, Patrick L

2012-04-02

One S less: recent crystallographic studies have revealed a new, oxygen-tolerant kind of iron-sulfide cluster [4Fe-3S], which contains only three rather than four sulfur atoms in its cage (see picture; yellow=S, red=Fe, blue=N, green=cysteine). It is proposed that the cluster's ability to transfer multiple electrons increases the oxygen tolerance by enabling the enzyme to reduce O(2) rapidly, converting the dioxygen into harmless water before it can damage the protein. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Graded hypoxia acts through a network of distributed peripheral oxygen chemoreceptors to produce changes in respiratory behaviour and plasticity.

PubMed

Janes, Tara A; Xu, Fenglian; Syed, Naweed I

2015-07-01

Respiratory behaviour relies critically upon sensory feedback from peripheral oxygen chemoreceptors. During environmental or systemic hypoxia, chemoreceptor input modulates respiratory central pattern generator activity to produce reflex-based increases in respiration and also shapes respiratory plasticity over longer timescales. The best-studied oxygen chemoreceptors are undoubtedly the mammalian carotid bodies; however, questions remain regarding this complex organ's role in shaping respiration in response to varying oxygen levels. Furthermore, many taxa possess distinct oxygen chemoreceptors located within the lungs, airways and cardiovasculature, but the functional advantage of multiple chemoreceptor sites is unclear. In this study, it is demonstrated that a distributed network of peripheral oxygen chemoreceptors exists in Lymnaea stagnalis and significantly modulates aerial respiration. Specifically, Lymnaea breath frequency and duration represent parameters that are shaped by interactions between hypoxic severity and its time-course. Using a combination of behaviour and electrophysiology approaches, the chemosensory pathways underlying hypoxia-induced changes in breath frequency/duration were explored. The current findings demonstrate that breath frequency is uniquely modulated by the known osphradial ganglion oxygen chemoreceptors during moderate hypoxia, while a newly discovered area of pneumostome oxygen chemoreception serves a similar function specifically during more severe hypoxia. Together, these findings suggest that multiple oxygen chemosensory sites, each with their own sensory and modulatory properties, act synergistically to form a functionally distributed network that dynamically shapes respiration in response to changing systemic or environmental oxygen levels. These distributed networks may represent an evolutionarily conserved strategy vis-à-vis respiratory adaptability and have significant implications for the understanding of fundamental respiratory control systems. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Generator configuration for solid oxide fuel cells

DOEpatents

Reichner, Philip

1989-01-01

Disclosed are improvements in a solid oxide fuel cell generator 1 having a multiplicity of electrically connected solid oxide fuel cells 2, where a fuel gas is passed over one side of said cells and an oxygen-containing gas is passed over the other side of said cells resulting in the generation of heat and electricity. The improvements comprise arranging the cells in the configuration of a circle, a spiral, or folded rows within a cylindrical generator, and modifying the flow rate, oxygen concentration, and/or temperature of the oxygen-containing gases that flow to those cells that are at the periphery of the generator relative to those cells that are at the center of the generator. In these ways, a more uniform temperature is obtained throughout the generator.

Effect of Spin Multiplicity in O2 Adsorption and Dissociation on Small Bimetallic AuAg Clusters.

PubMed

García-Cruz, Raúl; Poulain, Enrique; Hernández-Pérez, Isaías; Reyes-Nava, Juan A; González-Torres, Julio C; Rubio-Ponce, A; Olvera-Neria, Oscar

2017-08-17

To dispose of atomic oxygen, it is necessary the O 2 activation; however, an energy barrier must be overcome to break the O-O bond. This work presents theoretical calculations of the O 2 adsorption and dissociation on small pure Au n and Ag m and bimetallic Au n Ag m (n + m ≤ 6) clusters using the density functional theory (DFT) and the zeroth-order regular approximation (ZORA) to explicitly include scalar relativistic effects. The most stable Au n Ag m clusters contain a higher concentration of Au with Ag atoms located in the center of the cluster. The O 2 adsorption energy on pure and bimetallic clusters and the ensuing geometries depend on the spin multiplicity of the system. For a doublet multiplicity, O 2 is adsorbed in a bridge configuration, whereas for a triplet only one O-metal bond is formed. The charge transfer from metal toward O 2 occupies the σ* O-O antibonding natural bond orbital, which weakens the oxygen bond. The Au 3 ( 2 A) cluster presents the lowest activation energy to dissociate O 2 , whereas the opposite applies to the AuAg ( 3 A) system. In the O 2 activation, bimetallic clusters are not as active as pure Au n clusters due to the charge donated by Ag atoms being shared between O 2 and Au atoms.

POLAR ORGANIC OXYGENATES IN PM2.5 AT A SOUTHEASTERN SITE IN THE UNITED STATES

EPA Science Inventory

A field study was undertaken in Research Triangle Park, NC, USA, during the summer of 2000 to identify classes of polar oxygenates in PM2.5 containing carbonyl and/or hydroxyl functional groups and, to the extent possible, determine the individual particle-bound oxygenates that m...

Silicon nitride boundary lubrication: Effect of oxygenates

NASA Astrophysics Data System (ADS)

Gates, Richard S.; Hsu, Stephen M.

1995-07-01

A ball-on-three-flat (BTF) wear tester was used to investigate the boundary lubricating characteristics of oxygenates on a commercial silicon nitride. A wide variety of oxygen-containing compounds containing hydroxyl functioal groups were more effective compared to a base case of neat paraffin oil. Decreases of up to 58% in friction coefficient, and 95% in wear were obtained. In most cases, films were obseved in and around the wear scar, suggesting chemical reactions had taken place in the contact. Additional wear tests, conducted using neat shorter-chain linear primary alcohols, i.e., 6-10 carbons, demonstrated boundary lubrication protection, with longer chain length providing better antiwear performance. A study of several C8 compounds with specific oxygen-containing functional groups (primary alcohol, secondary alcohols, acid, aldehyde, and ketone) demonstrated that the primary alcohol had the strongest boundary lubricating effect. Varying the amount of water in the alcohols had little effect on friction and wear, suggesting that the boundary lubrication effects observed were not merely due to dissolved water in these fluids, but some characteristic chemical interaction with the hydroxyl functional group of the alcohols and acids.

The Complex Transcriptional Response of Acaryochloris marina to Different Oxygen Levels.

PubMed

Hernández-Prieto, Miguel A; Lin, Yuankui; Chen, Min

2017-02-09

Ancient oxygenic photosynthetic prokaryotes produced oxygen as a waste product, but existed for a long time under an oxygen-free (anoxic) atmosphere, before an oxic atmosphere emerged. The change in oxygen levels in the atmosphere influenced the chemistry and structure of many enzymes that contained prosthetic groups that were inactivated by oxygen. In the genome of Acaryochloris marina , multiple gene copies exist for proteins that are normally encoded by a single gene copy in other cyanobacteria. Using high throughput RNA sequencing to profile transcriptome responses from cells grown under microoxic and hyperoxic conditions, we detected 8446 transcripts out of the 8462 annotated genes in the Cyanobase database. Two-thirds of the 50 most abundant transcripts are key proteins in photosynthesis. Microoxic conditions negatively affected the levels of expression of genes encoding photosynthetic complexes, with the exception of some subunits. In addition to the known regulation of the multiple copies of psbA , we detected a similar transcriptional pattern for psbJ and psbU , which might play a key role in the altered components of photosystem II. Furthermore, regulation of genes encoding proteins important for reactive oxygen species-scavenging is discussed at genome level, including, for the first time, specific small RNAs having possible regulatory roles under varying oxygen levels. Copyright © 2017 Hernandez-Prieto et al.

The Complex Transcriptional Response of Acaryochloris marina to Different Oxygen Levels

PubMed Central

Hernández-Prieto, Miguel A.; Lin, Yuankui; Chen, Min

2016-01-01

Ancient oxygenic photosynthetic prokaryotes produced oxygen as a waste product, but existed for a long time under an oxygen-free (anoxic) atmosphere, before an oxic atmosphere emerged. The change in oxygen levels in the atmosphere influenced the chemistry and structure of many enzymes that contained prosthetic groups that were inactivated by oxygen. In the genome of Acaryochloris marina, multiple gene copies exist for proteins that are normally encoded by a single gene copy in other cyanobacteria. Using high throughput RNA sequencing to profile transcriptome responses from cells grown under microoxic and hyperoxic conditions, we detected 8446 transcripts out of the 8462 annotated genes in the Cyanobase database. Two-thirds of the 50 most abundant transcripts are key proteins in photosynthesis. Microoxic conditions negatively affected the levels of expression of genes encoding photosynthetic complexes, with the exception of some subunits. In addition to the known regulation of the multiple copies of psbA, we detected a similar transcriptional pattern for psbJ and psbU, which might play a key role in the altered components of photosystem II. Furthermore, regulation of genes encoding proteins important for reactive oxygen species-scavenging is discussed at genome level, including, for the first time, specific small RNAs having possible regulatory roles under varying oxygen levels. PMID:27974439

Measuring and predicting sooting tendencies of oxygenates, alkanes, alkenes, cycloalkanes, and aromatics on a unified scale

DOE PAGES

Das, Dhrubajyoti D.; St. John, Peter C.; McEnally, Charles S.; ...

2017-12-27

Databases of sooting indices, based on measuring some aspect of sooting behavior in a standardized combustion environment, are useful in providing information on the comparative sooting tendencies of different fuels or pure compounds. However, newer biofuels have varied chemical structures including both aromatic and oxygenated functional groups, which expands the chemical space of relevant compounds. In this work, we propose a unified sooting tendency database for pure compounds, including both regular and oxygenated hydrocarbons, which is based on combining two disparate databases of yield-based sooting tendency measurements in the literature. Unification of the different databases was made possible by leveragingmore » the greater dynamic range of the color ratio pyrometry soot diagnostic. This unified database contains a substantial number of pure compounds (≥ 400 total) from multiple categories of hydrocarbons important in modern fuels and establishes the sooting tendencies of aromatic and oxygenated hydrocarbons on the same numeric scale for the first time. Then, using this unified sooting tendency database, we have developed a predictive model for sooting behavior applicable to a broad range of hydrocarbons and oxygenated hydrocarbons. The model decomposes each compound into single-carbon fragments and assigns a sooting tendency contribution to each fragment based on regression against the unified database. The model’s predictive accuracy (as demonstrated by leave-one-out cross-validation) is comparable to a previously developed, more detailed predictive model. The fitted model provides insight into the effects of chemical structure on soot formation, and cases where its predictions fail reveal the presence of more complicated kinetic sooting mechanisms. Our work will therefore enable the rational design of low-sooting fuel blends from a wide range of feedstocks and chemical functionalities.« less

Measuring and predicting sooting tendencies of oxygenates, alkanes, alkenes, cycloalkanes, and aromatics on a unified scale

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

Das, Dhrubajyoti D.; St. John, Peter C.; McEnally, Charles S.

Databases of sooting indices, based on measuring some aspect of sooting behavior in a standardized combustion environment, are useful in providing information on the comparative sooting tendencies of different fuels or pure compounds. However, newer biofuels have varied chemical structures including both aromatic and oxygenated functional groups, which expands the chemical space of relevant compounds. In this work, we propose a unified sooting tendency database for pure compounds, including both regular and oxygenated hydrocarbons, which is based on combining two disparate databases of yield-based sooting tendency measurements in the literature. Unification of the different databases was made possible by leveragingmore » the greater dynamic range of the color ratio pyrometry soot diagnostic. This unified database contains a substantial number of pure compounds (≥ 400 total) from multiple categories of hydrocarbons important in modern fuels and establishes the sooting tendencies of aromatic and oxygenated hydrocarbons on the same numeric scale for the first time. Then, using this unified sooting tendency database, we have developed a predictive model for sooting behavior applicable to a broad range of hydrocarbons and oxygenated hydrocarbons. The model decomposes each compound into single-carbon fragments and assigns a sooting tendency contribution to each fragment based on regression against the unified database. The model’s predictive accuracy (as demonstrated by leave-one-out cross-validation) is comparable to a previously developed, more detailed predictive model. The fitted model provides insight into the effects of chemical structure on soot formation, and cases where its predictions fail reveal the presence of more complicated kinetic sooting mechanisms. Our work will therefore enable the rational design of low-sooting fuel blends from a wide range of feedstocks and chemical functionalities.« less

Linking Carbonic Anhydrase Abundance and Diversity in Soils to Ecological Function

NASA Astrophysics Data System (ADS)

Pang, E.; Meredith, L. K.; Welander, P. V.

2015-12-01

Carbonic anhydrase (CA) is an ancient enzyme widespread among bacteria, archaea, and eukarya that catalyzes the following reaction: CO2 + H2O ⇌ HCO3- + H+. Its functions are critical for key cellular processes such as concentrating CO2 for autotrophic growth, pH regulation, and pathogen survival in hosts. Currently, there are six known CA classes (α, β, γ, δ, η, ζ) arising from several distinct evolutionary lineages. CA are widespread in sequenced genomes, with many organisms containing multiple classes of CA or multiple CA of the same class. Soils host rich microbial communities with diverse and important ecological functions, but the diversity and abundance of CA in soils has not been explored. CA appears to play an important, but poorly understood, role in some biogeochemical cycles such as those of CO2 and its oxygen isotope composition and also carbonyl sulfide (COS), which are potential tracers in predictive carbon cycle models. Recognizing the prevalence and functional significance of CA in soils, we used a combined bioinformatics and molecular biology approach to address fundamental questions regarding the abundance, diversity, and function of CA in soils. To characterize the abundance and diversity of the different CA classes in soils, we analyzed existing soil metagenomic and metatranscriptomic data from the DOE Joint Genome Institute databases. Out of the six classes of CA, we only found the α, β, and γ classes to be present in soils, with the β class being the most abundant. We also looked at genomes of sequenced soil microorganisms to learn what combination of CA classes they contain, from which we can begin to predict the physiological role of CA. To characterize the functional roles of the different CA classes in soils, we collected soil samples from a variety of biomes with diverse chemical and physical properties and quantified the rate of two CA-mediated processes: soil uptake of COS and acceleration of the oxygen isotope exchange between CO2 and H2O. We employed PCR-based methods to quantify the abundance and diversity of CA encoding genes and their expression in our samples to link CA classes to the gas flux data. These studies provide the first survey of CA in soils, a step towards understanding CA's potentially significant role in microbial survival and microbe-mediated biogeochemical cycles.

Simultaneous reduction and nitrogen functionalization of graphene oxide using lemon for metal-free oxygen reduction reaction

NASA Astrophysics Data System (ADS)

Begum, Halima; Ahmed, Mohammad Shamsuddin; Cho, Sung; Jeon, Seungwon

2017-12-01

Inspire by the vision of finding a simple and green method for simultaneous reduction and nitrogen (N)-functionalization of graphene oxide (GO), a N-rich reduced graphene oxide (rGO) has been synthesized through a facile and ecofriendly hydrothermal strategy while most of the existing methods are involving with multiple steps and highly toxic reducing agents that are harmful to human health and environment. In this paper, the simultaneous reduction and N-functionalization of GO using as available lemon juice (denoted as Lem-rGO) for metal-free electrocatalysis towards oxygen reduction reaction (ORR) is described. The proposed method is based on the reduction of GO using of the reducing and the N-precursor capability of ascorbic acid and citric acid as well as the nitrogenous compounds, respectively, that containing in lemon juice. The resultant Lem-rGO has higher reduction degree, higher specific surface area and better crystalline nature with N-incorporation than that of well investigated ascorbic acid and citric acid treated rGO. As a result, it shows better ORR electrocatalytic activity in respect to the improved onset potential, electron transfer rate and kinetics than those typical rGO catalysts. Moreover, it shows a significant tolerance to the anodic fuels and durability than the Pt/C during ORR.

Site-selective oxidation, amination and epimerization reactions of complex polyols enabled by transfer hydrogenation

NASA Astrophysics Data System (ADS)

Hill, Christopher K.; Hartwig, John F.

2017-12-01

Polyoxygenated hydrocarbons that bear one or more hydroxyl groups comprise a large set of natural and synthetic compounds, often with potent biological activity. In synthetic chemistry, alcohols are important precursors to carbonyl groups, which then can be converted into a wide range of oxygen- or nitrogen-based functionality. Therefore, the selective conversion of a single hydroxyl group in natural products into a ketone would enable the selective introduction of unnatural functionality. However, the methods known to convert a simple alcohol, or even an alcohol in a molecule that contains multiple protected functional groups, are not suitable for selective reactions of complex polyol structures. We present a new ruthenium catalyst with a unique efficacy for the selective oxidation of a single hydroxyl group among many in unprotected polyol natural products. This oxidation enables the introduction of nitrogen-based functional groups into such structures that lack nitrogen atoms and enables a selective alcohol epimerization by stepwise or reversible oxidation and reduction.

Impact of Polymer Electrolyte Membrane Degradation Products on Oxygen Reduction Reaction Activity for Platinum Electrocatalysts

DOE PAGES

Christ, J. M.; Neyerlin, K. C.; Wang, H.; ...

2014-10-30

The impact of model membrane degradation compounds on the relevant electrochemical parameters for the oxygen reduction reaction (i.e. electrochemical surface area and catalytic activity), was studied for both polycrystalline Pt and carbon supported Pt electrocatalysts. Model compounds, representing previously published, experimentally determined polymer electrolyte membrane degradation products, were in the form of perfluorinated organic acids that contained combinations of carboxylic and/or sulfonic acid functionality. Perfluorinated carboxylic acids of carbon chain length C1 – C6 were found to have an impact on electrochemical surface area (ECA). The longest chain length acid also hindered the observed oxygen reduction reaction (ORR) performance, resultingmore » in a 17% loss in kinetic current (determined at 0.9 V). Model compounds containing sulfonic acid functional groups alone did not show an effect on Pt ECA or ORR activity. Lastly, greater than a 44% loss in ORR activity at 0.9V was observed for diacid model compounds DA-Naf (perfluoro(2-methyl-3-oxa-5-sulfonic pentanoic) acid) and DA-3M (perfluoro(4-sulfonic butanoic) acid), which contained both sulfonic and carboxylic acid functionalities.« less

Statistical Exposé of a Multiple-Compartment Anaerobic Reactor Treating Domestic Wastewater.

PubMed

Pfluger, Andrew R; Hahn, Martha J; Hering, Amanda S; Munakata-Marr, Junko; Figueroa, Linda

2018-06-01

  Mainstream anaerobic treatment of domestic wastewater is a promising energy-generating treatment strategy; however, such reactors operated in colder regions are not well characterized. Performance data from a pilot-scale, multiple-compartment anaerobic reactor taken over 786 days were subjected to comprehensive statistical analyses. Results suggest that chemical oxygen demand (COD) was a poor proxy for organics in anaerobic systems as oxygen demand from dissolved inorganic material, dissolved methane, and colloidal material influence dissolved and particulate COD measurements. Additionally, univariate and functional boxplots were useful in visualizing variability in contaminant concentrations and identifying statistical outliers. Further, significantly different dissolved organic removal and methane production was observed between operational years, suggesting that anaerobic reactor systems may not achieve steady-state performance within one year. Last, modeling multiple-compartment reactor systems will require data collected over at least two years to capture seasonal variations of the major anaerobic microbial functions occurring within each reactor compartment.

The RavA-ViaA Chaperone-Like System Interacts with and Modulates the Activity of the Fumarate Reductase Respiratory Complex.

PubMed

Wong, Keith S; Bhandari, Vaibhav; Janga, Sarath Chandra; Houry, Walid A

2017-01-20

Regulatory ATPase variant A (RavA) is a MoxR AAA+ protein that functions together with a partner protein that we termed VWA interacting with AAA+ ATPase (ViaA) containing a von Willebrand Factor A domain. However, the functional role of RavA-ViaA in the cell is not yet well established. Here, we show that RavA-ViaA are functionally associated with anaerobic respiration in Escherichia coli through interactions with the fumarate reductase (Frd) electron transport complex. Expression analysis of ravA and viaA genes showed that both proteins are co-expressed with multiple anaerobic respiratory genes, many of which are regulated by the anaerobic transcriptional regulator Fnr. Consistently, the expression of both ravA and viaA was found to be dependent on Fnr in cells grown under oxygen-limiting condition. ViaA was found to physically interact with FrdA, the flavin-containing subunit of the Frd complex. Both RavA and the Fe-S-containing subunit of the Frd complex, FrdB, regulate this interaction. Importantly, Frd activity was observed to increase in the absence of RavA and ViaA. This indicates that RavA and ViaA modulate the activity of the Frd complex, signifying a potential regulatory chaperone-like function for RavA-ViaA during bacterial anaerobic respiration with fumarate as the terminal electron acceptor. Copyright © 2016 Elsevier Ltd. All rights reserved.

Early benthic successional processes at implanted substrates in Barkley Submarine Canyon affected by a permanent oxygen minimum zone

NASA Astrophysics Data System (ADS)

Cabrera De Leo, F.; Smith, C. R.; Levin, L. A.; Fleury, A.; Aguzzi, J.

2016-02-01

With the advent of cabled observatories scientists are now able to have a permanent presence in the deep-seafloor, being able to reveal previously unseen faunal behavior as well as to track long-term changes in biodiversity and ecosystem function. The Ocean Networks Canada 800-km loop seafloor observatory array (NEPTUNE) located in the NE Pacific has instruments measuring a variety of environmental variables ranging from temperature, salinity, oxygen, currents, turbidity, fluorescence, etc, at multiple and very high temporal resolution scales. High-definition video cameras also monitor benthic communities in multiple deep-sea habitats, all at some extent influenced by an oxygen minimum zone (OMZ). In the present study, whale-bone and wood substrates are being used to evaluate bathymetric, regional and inter-basin variations in benthic biodiversity and connectivity, as well as interactions between biodiversity and ecosystem function. In May of 2014 three humpback whale (Megaptera novaeangliae) rib sections, one 20x20x10 cm block of Douglas Fir (Pseudotsunga meniziesii), and a 30x30x30 block of authigenic carbonate were placed with the use of an ROV at 890 m depth inside Barkley Canyon. The substrate packages were placed concentrically, 45-cm away from a HD video camera. Five-minute videos were captured at 2-hr intervals. Preliminary data analysis from 8 months of deployment showed very distinct early community succession patterns between the two organic substrates (bones and wood) and the authigenic carbonate. Whalebones and wood showed amphipod (Orchomene obtusa) abundance peaks mostly contained during the first 60 days after deployment; Amphipod peak abundance rapid decline coincides with rapid growth of bacterial mat on whalebone and wood surfaces. Low abundance, species richness and substrate degradation rates are in agreement with a low oxygen environment of the OMZ in the canyon. Despite the early stages of data analysis, this experiment demonstrates how cabled observatories are suited for conducting experiments in the deep-sea, where researchers gain full control of observation parameters and benefit from high-frequency measuring of environmental fluctuation.

Corner heating in rectangular solid oxide electrochemical cell generators

DOEpatents

Reichner, Philip

1989-01-01

Disclosed is an improvement in a solid oxide electrochemical cell generator 1 having a rectangular design with four sides that meet at corners, and containing multiplicity of electrically connected fuel cells 11, where a fuel gas is passed over one side of said cells and an oxygen containing gas is passed into said cells, and said fuel is burned to form heat, electricity, and an exhaust gas. The improvement comprises passing the exhaust gases over the multiplicity of cells 11 in such a way that more of the heat in said exhaust gases flows at the corners of the generator, such as through channels 19.

A computer-based matrix for rapid calculation of pulmonary hemodynamic parameters in congenital heart disease

PubMed Central

Lopes, Antonio Augusto; dos Anjos Miranda, Rogério; Gonçalves, Rilvani Cavalcante; Thomaz, Ana Maria

2009-01-01

BACKGROUND: In patients with congenital heart disease undergoing cardiac catheterization for hemodynamic purposes, parameter estimation by the indirect Fick method using a single predicted value of oxygen consumption has been a matter of criticism. OBJECTIVE: We developed a computer-based routine for rapid estimation of replicate hemodynamic parameters using multiple predicted values of oxygen consumption. MATERIALS AND METHODS: Using Microsoft® Excel facilities, we constructed a matrix containing 5 models (equations) for prediction of oxygen consumption, and all additional formulas needed to obtain replicate estimates of hemodynamic parameters. RESULTS: By entering data from 65 patients with ventricular septal defects, aged 1 month to 8 years, it was possible to obtain multiple predictions for oxygen consumption, with clear between-age groups (P <.001) and between-methods (P <.001) differences. Using these predictions in the individual patient, it was possible to obtain the upper and lower limits of a likely range for any given parameter, which made estimation more realistic. CONCLUSION: The organized matrix allows for rapid obtainment of replicate parameter estimates, without error due to exhaustive calculations. PMID:19641642

Genetic Diversity of Coastal Bottlenose Dolphins Revealed by Structurally and Functionally Diverse Hemoglobins

PubMed Central

Remington, Nicole; Stevens, Robert D.; Wells, Randall S.; Hohn, Aleta; Dhungana, Suraj; Taboy, Celine H.; Crumbliss, Alvin L.; Henkens, Robert; Bonaventura, Celia

2007-01-01

Studies of structure-function relationships in the respiratory proteins of marine mammals revealed unexpected variations in the number and types of hemoglobins (Hbs) present in coastal bottlenose dolphins, Tursiops truncatus. We obtained blood samples from free-ranging coastal bottlenose dolphins as a component of capture-release studies. We found that the oxygen-binding functions of bottlenose dolphin blood are poised between effector-saturated and unsaturated levels, enabling exercise-dependent shifts in oxygen transfer functions. Isolated bottlenose dolphin Hbs showed elevated pH sensitivities (Bohr effects) and appreciably lower oxygen affinities than adult human Hb in the absence of allosteric effectors. These properties may be an adaptive modification that enhance oxygen delivery during diving episodes when oxygen tensions and effector levels are low. The Hbs of individual dolphins showed similar oxygen affinities, responses to effectors, and expression of heme-heme interaction in oxygen binding, but differed in their redox potentials and rates of autoxidation. The heterogeneity suggested by these functional variations in Hbs of individual dolphins was born out by variations in the molecular weights and numbers of their α and β globin chains. Although coastal bottlenose dolphins were expected to have a single type of Hb, the mass differences observed revealed considerable genetic diversity. There were multiple Hb forms in some individuals and differences in Hb patterns among individuals within the same community. PMID:17604574

Genetic diversity of coastal bottlenose dolphins revealed by structurally and functionally diverse hemoglobins.

PubMed

Remington, Nicole; Stevens, Robert D; Wells, Randall S; Holn, Aleta; Dhungana, Suraj; Taboy, Celine H; Crumbliss, Alvin L; Henkens, Robert; Bonaventura, Celia

2007-08-15

Studies of structure-function relationships in the respiratory proteins of marine mammals revealed unexpected variations in the number and types of hemoglobins (Hbs) present in coastal bottlenose dolphins, Tursiops truncatus. We obtained blood samples from free-ranging coastal bottlenose dolphins as a component of capture-release studies. We found that the oxygen-binding functions of bottlenose dolphin blood are poised between effector-saturated and unsaturated levels, enabling exercise-dependent shifts in oxygen transfer functions. Isolated bottlenose dolphin Hbs showed elevated pH sensitivities (Bohr effects) and appreciably lower oxygen affinities than adult human Hb in the absence of allosteric effectors. These properties may be an adaptive modification that enhances oxygen delivery during diving episodes when oxygen tensions and effector levels are low. The Hbs of individual dolphins showed similar oxygen affinities, responses to effectors, and expression of heme-heme interaction in oxygen binding, but differed in their redox potentials and rates of autoxidation. The heterogeneity suggested by these functional variations in Hbs of individual dolphins was born out by variations in the molecular weights and numbers of their alpha and beta globin chains. Although coastal bottlenose dolphins were expected to have a single type of Hb, the mass differences observed revealed considerable genetic diversity. There were multiple Hb forms in some individuals and differences in Hb patterns among individuals within the same community.

Low work function, stable compound clusters and generation process

DOEpatents

Dinh, Long N.; Balooch, Mehdi; Schildbach, Marcus A.; Hamza, Alex V.; McLean, II, William

2000-01-01

Low work function, stable compound clusters are generated by co-evaporation of a solid semiconductor (i.e., Si) and alkali metal (i.e., Cs) elements in an oxygen environment. The compound clusters are easily patterned during deposition on substrate surfaces using a conventional photo-resist technique. The cluster size distribution is narrow, with a peak range of angstroms to nanometers depending on the oxygen pressure and the Si source temperature. Tests have shown that compound clusters when deposited on a carbon substrate contain the desired low work function property and are stable up to 600.degree. C. Using the patterned cluster containing plate as a cathode baseplate and a faceplate covered with phosphor as an anode, one can apply a positive bias to the faceplate to easily extract electrons and obtain illumination.

Continuous optical measurement system of hemolysis during a photosensitization reaction using absorption spectrum

NASA Astrophysics Data System (ADS)

Hamada, R.; Ogawa, E.; Arai, T.

2018-02-01

To investigate hemolysis phenomena during a photosensitization reaction with the reaction condition continuously and simultaneously for a safety assessment of hemolysis side effect, we constructed an optical system to measure blood sample absorption spectrum during the reaction. Hemolysis degree might be under estimated in general evaluation methods because there is a constant oxygen pressure assumption in spite of oxygen depression take place. By investigating hemoglobin oxidation and oxygen desorption dynamics obtained from the contribution of the visible absorption spectrum and multiple regression analysis, both the hemolysis phenomena and its oxygen environment might be obtained with time. A 664 nm wavelength laser beam for the reaction excitation and 475-650 nm light beam for measuring the absorbance spectrum were arranged perpendicularly crossing. A quartz glass cuvette with 1×10 mm in dimensions for the spectrum measurement was located at this crossing point. A red blood cells suspension medium was arranged with low hematocrit containing 30 μg/ml talaporfin sodium. This medium was irradiated up to 40 J/cm2 . The met-hemoglobin, oxygenatedhemoglobin, and deoxygenated-hemoglobin concentrations were calculated by a multiple regression analysis from the measured spectra. We confirmed the met-hemoglobin concentration increased and oxygen saturation decreased with the irradiation time, which seems to indicate the hemolysis progression and oxygen consumption, respectively. By using our measuring system, the hemolysis progression seems to be obtained with oxygen environment information.

Loss of SLP-76 expression within myeloid cells confers resistance to neutrophil-mediated tissue damage while maintaining effective bacterial killing.

PubMed

Clemens, Regina A; Lenox, Laurie E; Kambayashi, Taku; Bezman, Natalie; Maltzman, Jonathan S; Nichols, Kim E; Koretzky, Gary A

2007-04-01

The Src homology 2 domain-containing leukocyte phosphoprotein of 76 kDa (SLP-76) is an adaptor molecule critical for immunoreceptor and integrin signaling in multiple hemopoietic lineages. We showed previously that SLP-76 is required for neutrophil function in vitro, including integrin-induced adhesion and production of reactive oxygen intermediates, and to a lesser extent, FcgammaR-induced calcium flux and reactive oxygen intermediate production. It has been difficult to determine whether SLP-76 regulates neutrophil responses in vivo, because Slp-76(-/-) mice exhibit marked defects in thymocyte and vascular development, as well as platelet and mast cell function. To circumvent these issues, we generated mice with targeted loss of SLP-76 expression within myeloid cells. Neutrophils obtained from these animals failed to respond to integrin activation in vitro, similar to Slp-76(-/-) cells. Despite these abnormalities, SLP-76-deficient neutrophils migrated normally in vivo in response to Staphylococcus aureus infection and efficiently cleared micro-organisms. Interestingly, SLP-76-deficient neutrophils did not induce a robust inflammatory response in the localized Shwartzman reaction. Collectively, these data suggest that disruption of integrin signaling via loss of SLP-76 expression differentially impairs neutrophil functions in vivo, with preservation of migration and killing of S. aureus but reduction in LPS-induced tissue damage and vascular injury.

Resting-state blood oxygen level-dependent functional magnetic resonance imaging for presurgical planning.

PubMed

Kamran, Mudassar; Hacker, Carl D; Allen, Monica G; Mitchell, Timothy J; Leuthardt, Eric C; Snyder, Abraham Z; Shimony, Joshua S

2014-11-01

Resting-state functional MR imaging (rsfMR imaging) measures spontaneous fluctuations in the blood oxygen level-dependent (BOLD) signal and can be used to elucidate the brain's functional organization. It is used to simultaneously assess multiple distributed resting-state networks. Unlike task-based functional MR imaging, rsfMR imaging does not require task performance. This article presents a brief introduction of rsfMR imaging processing methods followed by a detailed discussion on the use of rsfMR imaging in presurgical planning. Example cases are provided to highlight the strengths and limitations of the technique. Copyright © 2014 Elsevier Inc. All rights reserved.

[Sauna effect on blood oxygen transport function and proxidant/antioxidant balance in youths].

PubMed

Zinchuk, V V; Zhad'ko, D D

2012-01-01

There was investigated sauna effect on blood oxygen transport function and proxidant/antioxidant balance in 18 to 22 years old males. Subjects being tested underwent thermal exposure once per week over a period of 5 months (20 procedures). There were two exposure over the course of sauna bathing (temperature 85-90 degrees C, humidity 10-15%): the first exposure lasted for 5 minutes and the second one for 10 minutes. Dry air sauna in youth's leads to respiratory alkalosis, increases pO2, decreases haemoglobin binding capacity to venous blood oxygen thus facilitating oxygen transport into body tissues. Single sauna visit results in oxidative stress (augmentation of free radical processes and deterioration of antioxidant defence mechanisms), while its manifestations being diminished after multiple thermal exposures. Increase in nitrogen monoxide formation being observed might matter for the modification of the oxygen dependent processes of the human body.

Radiosensitizing Pancreatic Cancer Xenografts by an Implantable Micro-Oxygen Generator.

PubMed

Cao, Ning; Song, Seung Hyun; Maleki, Teimour; Shaffer, Michael; Stantz, Keith M; Cao, Minsong; Kao, Chinghai; Mendonca, Marc S; Ziaie, Babak; Ko, Song-Chu

2016-04-01

Over the past decades, little progress has been made to improve the extremely low survival rates in pancreatic cancer patients. Extreme hypoxia observed in pancreatic tumors contributes to the aggressive and metastatic characteristics of this tumor and can reduce the effectiveness of conventional radiation therapy and chemotherapy. In an attempt to reduce hypoxia-induced obstacles to effective radiation treatment, we used a novel device, the implantable micro-oxygen generator (IMOG), for in situ tumor oxygenation. After subcutaneous implantation of human pancreatic xenograft tumors in athymic rats, the IMOG was wirelessly powered by ultrasonic waves, producing 30 μA of direct current (at 2.5 V), which was then utilized to electrolyze water and produce oxygen within the tumor. Significant oxygen production by the IMOG was observed and corroborated using the NeoFox oxygen sensor dynamically. To test the radiosensitization effect of the newly generated oxygen, the human pancreatic xenograft tumors were subcutaneously implanted in nude mice with either a functional or inactivated IMOG device. The tumors in the mice were then exposed to ultrasonic power for 10 min, followed by a single fraction of 5 Gy radiation, and tumor growth was monitored thereafter. The 5 Gy irradiated tumors containing the functional IMOG exhibited tumor growth inhibition equivalent to that of 7 Gy irradiated tumors that did not contain an IMOG. Our study confirmed that an activated IMOG is able to produce sufficient oxygen to radiosensitize pancreatic tumors, enhancing response to single-dose radiation therapy.

Oxygen demand of perfused heart preparations: how electromechanical function and inadequate oxygenation affect physiology and optical measurements.

PubMed

Kuzmiak-Glancy, Sarah; Jaimes, Rafael; Wengrowski, Anastasia M; Kay, Matthew W

2015-06-01

What is the topic of this review? This review discusses how the function and electrophysiology of isolated perfused hearts are affected by oxygenation and energy utilization. The impact of oxygenation on fluorescence measurements in perfused hearts is also discussed. What advances does it highlight? Recent studies have illuminated the inherent differences in electromechanical function, energy utilization rate and oxygen requirements between the primary types of excised heart preparations. A summary and analysis of how these variables affect experimental results are necessary to elevate the physiological relevance of these approaches in order to advance the field of whole-heart research. The ex vivo perfused heart recreates important aspects of in vivo conditions to provide insight into whole-organ function. In this review we discuss multiple types of ex vivo heart preparations, explain how closely each mimic in vivo function, and discuss how changes in electromechanical function and inadequate oxygenation of ex vivo perfused hearts may affect measurements of physiology. Hearts that perform physiological work have high oxygen demand and are likely to experience hypoxia when perfused with a crystalloid perfusate. Adequate myocardial oxygenation is critically important for obtaining physiologically relevant measurements, so when designing experiments the type of ex vivo preparation and the capacity of perfusate to deliver oxygen must be carefully considered. When workload is low, such as during interventions that inhibit contraction, oxygen demand is also low, which could dramatically alter a physiological response to experimental variables. Changes in oxygenation also alter the optical properties of cardiac tissue, an effect that may influence optical signals measured from both endogenous and exogenous fluorophores. Careful consideration of oxygen supply, working condition, and wavelengths used to acquire optical signals is critical for obtaining physiologically relevant measurements during ex vivo perfused heart studies. © 2015 The Authors. Experimental Physiology © 2015 The Physiological Society.

Localized versus itinerant states created by multiple oxygen vacancies in SrTiO3

NASA Astrophysics Data System (ADS)

Jeschke, Harald O.; Shen, Juan; Valentí, Roser

2015-02-01

Oxygen vacancies in strontium titanate surfaces (SrTiO3) have been linked to the presence of a two-dimensional electron gas with unique behavior. We perform a detailed density functional theory study of the lattice and electronic structure of SrTiO3 slabs with multiple oxygen vacancies, with a main focus on two vacancies near a titanium dioxide terminated SrTiO3 surface. We conclude based on total energies that the two vacancies preferably inhabit the first two layers, i.e. they cluster vertically, while in the direction parallel to the surface, the vacancies show a weak tendency towards equal spacing. Analysis of the nonmagnetic electronic structure indicates that oxygen defects in the surface TiO2 layer lead to population of Ti {{t}2g} states and thus itinerancy of the electrons donated by the oxygen vacancy. In contrast, electrons from subsurface oxygen vacancies populate Ti eg states and remain localized on the two Ti ions neighboring the vacancy. We find that both the formation of a bound oxygen-vacancy state composed of hybridized Ti 3eg and 4p states neighboring the oxygen vacancy as well as the elastic deformation after extracting oxygen contribute to the stabilization of the in-gap state.

Calibrated imaging reveals altered grey matter metabolism related to white matter microstructure and symptom severity in multiple sclerosis.

PubMed

Hubbard, Nicholas A; Turner, Monroe P; Ouyang, Minhui; Himes, Lyndahl; Thomas, Binu P; Hutchison, Joanna L; Faghihahmadabadi, Shawheen; Davis, Scott L; Strain, Jeremy F; Spence, Jeffrey; Krawczyk, Daniel C; Huang, Hao; Lu, Hanzhang; Hart, John; Frohman, Teresa C; Frohman, Elliot M; Okuda, Darin T; Rypma, Bart

2017-11-01

Multiple sclerosis (MS) involves damage to white matter microstructures. This damage has been related to grey matter function as measured by standard, physiologically-nonspecific neuroimaging indices (i.e., blood-oxygen-level dependent signal [BOLD]). Here, we used calibrated functional magnetic resonance imaging and diffusion tensor imaging to examine the extent to which specific, evoked grey matter physiological processes were associated with white matter diffusion in MS. Evoked changes in BOLD, cerebral blood flow (CBF), and oxygen metabolism (CMRO 2 ) were measured in visual cortex. Individual differences in the diffusion tensor measure, radial diffusivity, within occipital tracts were strongly associated with MS patients' BOLD and CMRO 2 . However, these relationships were in opposite directions, complicating the interpretation of the relationship between BOLD and white matter microstructural damage in MS. CMRO 2 was strongly associated with individual differences in patients' fatigue and neurological disability, suggesting that alterations to evoked oxygen metabolic processes may be taken as a marker for primary symptoms of MS. This work demonstrates the first application of calibrated and diffusion imaging together and details the first application of calibrated functional MRI in a neurological population. Results lend support for neuroenergetic hypotheses of MS pathophysiology and provide an initial demonstration of the utility of evoked oxygen metabolism signals for neurology research. Hum Brain Mapp 38:5375-5390, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Oximeter for reliable clinical determination of blood oxygen saturation in a fetus

DOEpatents

Robinson, Mark R.; Haaland, David M.; Ward, Kenneth J.

1996-01-01

With the crude instrumentation now in use to continuously monitor the status of the fetus at delivery, the obstetrician and labor room staff not only over-recognize the possibility of fetal distress with the resultant rise in operative deliveries, but at times do not identify fetal distress which may result in preventable fetal neurological harm. The invention, which addresses these two basic problems, comprises a method and apparatus for non-invasive determination of blood oxygen saturation in the fetus. The apparatus includes a multiple frequency light source which is coupled to an optical fiber. The output of the fiber is used to illuminate blood containing tissue of the fetus. In the preferred embodiment, the reflected light is transmitted back to the apparatus where the light intensities are simultaneously detected at multiple frequencies. The resulting spectrum is then analyzed for determination of oxygen saturation. The analysis method uses multivariate calibration techniques that compensate for nonlinear spectral response, model interfering spectral responses and detect outlier data with high sensitivity.

The myoglobin of Emperor penguin (Aptenodytes forsteri): amino acid sequence and functional adaptation to extreme conditions.

PubMed

Tamburrini, M; Romano, M; Giardina, B; di Prisco, G

1999-02-01

In the framework of a study on molecular adaptations of the oxygen-transport and storage systems to extreme conditions in Antarctic marine organisms, we have investigated the structure/function relationship in Emperor penguin (Aptenodytes forsteri) myoglobin, in search of correlation with the bird life style. In contrast with previous reports, the revised amino acid sequence contains one additional residue and 15 differences. The oxygen-binding parameters seem well adapted to the diving behaviour of the penguin and to the environmental conditions of the Antarctic habitat. Addition of lactate has no major effect on myoglobin oxygenation over a large temperature range. Therefore, metabolic acidosis does not impair myoglobin function under conditions of prolonged physical effort, such as diving.

Hypoxia Induced Impairment of NK Cell Cytotoxicity against Multiple Myeloma Can Be Overcome by IL-2 Activation of the NK Cells

PubMed Central

Sarkar, Subhashis; Germeraad, Wilfred T. V.; Rouschop, Kasper M. A.; Steeghs, Elisabeth M. P.; van Gelder, Michel; Bos, Gerard M. J.; Wieten, Lotte

2013-01-01

Background Multiple Myeloma (MM) is an incurable plasma cell malignancy residing within the bone marrow (BM). We aim to develop allogeneic Natural Killer (NK) cell immunotherapy for MM. As the BM contains hypoxic regions and the tumor environment can be immunosuppressive, we hypothesized that hypoxia inhibits NK cell anti-MM responses. Methods NK cells were isolated from healthy donors by negative selection and NK cell function and phenotype were examined at oxygen levels representative of hypoxic BM using flowcytometry. Additionally, NK cells were activated with IL-2 to enhance NK cell cytotoxicity under hypoxia. Results Hypoxia reduced NK cell killing of MM cell lines in an oxygen dependent manner. Under hypoxia, NK cells maintained their ability to degranulate in response to target cells, though, the percentage of degranulating NK cells was slightly reduced. Adaptation of NK- or MM cells to hypoxia was not required, hence, the oxygen level during the killing process was critical. Hypoxia did not alter surface expression of NK cell ligands (HLA-ABC, -E, MICA/B and ULBP1-2) and receptors (KIR, NKG2A/C, DNAM-1, NCRs and 2B4). It did, however, decrease expression of the activating NKG2D receptor and of intracellular perforin and granzyme B. Pre-activation of NK cells by IL-2 abrogated the detrimental effects of hypoxia and increased NKG2D expression. This emphasized that activated NK cells can mediate anti-MM effects, even under hypoxic conditions. Conclusions Hypoxia abolishes the killing potential of NK cells against multiple myeloma, which can be restored by IL-2 activation. Our study shows that for the design of NK cell-based immunotherapy it is necessary to study biological interactions between NK- and tumor cells also under hypoxic conditions. PMID:23724099

Electrocatalytic hydrogenation and hydrodeoxygenation of oxygenated and unsaturated organic compounds

DOEpatents

Jackson, James E.; Lam, Chun Ho; Saffron, Christopher M.; Miller, Dennis J.

2018-04-24

A process and related electrode composition are disclosed for the electrocatalytic hydrogenation and/or hydrodeoxygenation of organic substrates such as biomass-derived bio-oil components by the production of hydrogen atoms on a catalyst surface followed by the reaction of the hydrogen atoms with the organic reactants. Biomass fast pyrolysis-derived bio-oil is a liquid mixture containing hundreds of organic compounds with chemical functionalities that are corrosive to container materials and are prone to polymerization. A high surface area skeletal metal catalyst material such as Raney Nickel can be used as the cathode. Electrocatalytic hydrogenation and/or hydrodeoxygenation convert the organic substrates under mild conditions to reduce coke formation and catalyst deactivation. The process converts oxygen-containing functionalities and unsaturated bonds into chemically reduced forms with an increased hydrogen content. The process is operated at mild conditions, which enables it to be a good means for stabilizing bio-oil to a form that can be stored and transported using metal containers and pipes.

Introduction to the Portable Life Support Schematic and Technology Development Components

NASA Technical Reports Server (NTRS)

Conger, Bruce

2008-01-01

Conger presented the operations and functions of the baseline Constellation Program (CxP) Portable Life Support System (PLSS) schematic and key development technologies. He explained the functional descriptions of the schematic components in the fluid systems of the PLSS for multiple operational scenarios. PLSS subsystems include the oxygen subsystem, the ventilation subsystem, and the thermal subsystem. He also presented the operational PLSS modes: Nominal EVA mode, Umbilical - no recharge mode, Umbilical - with recharge mode, BENDS mode, BUDDY mode, Secondary oxygen mode, and the PLSS-removed umbilical mode.

Health related quality of life in patients with congestive heart failure: comparison with other chronic diseases and relation to functional variables

PubMed Central

Juenger, J; Schellberg, D; Kraemer, S; Haunstetter, A; Zugck, C; Herzog, W; Haass, M

2002-01-01

Objective: To assess health related quality of life of patients with congestive heart failure; to compare their quality of life with the previously characterised general population and in those with other chronic diseases; and to correlate the different aspects of quality of life with relevant somatic variables. Setting: University hospital. Patients and design: A German version of the generic quality of life measure (SF-36) containing eight dimensions was administered to 205 patients with congestive heart failure and systolic dysfunction. Cardiopulmonary evaluation included assessment of New York Heart Association (NYHA) functional class, left ventricular ejection fraction, peak oxygen uptake, and the distance covered during a standardised six minute walk test. Results: Quality of life significantly decreased with NYHA functional class (linear trend: p < 0.0001). In NYHA class III, the scores of five of the eight quality of life domains were reduced to around one third of those in the general population. The pattern of reduction was different in patients with chronic hepatitis C and major depression, and similar in patients on chronic haemodialysis. Multiple regression analysis showed that only the NYHA functional class was consistently and closely associated with all quality of life scales. The six minute walk test and peak oxygen uptake added to the explanation of the variance in only one of the eight quality of life domains (physical functioning). Left ventricular ejection fraction, duration of disease, and age showed no clear association with quality of life. Conclusions: In congestive heart failure, quality of life decreases as NYHA functional class worsens. Though NYHA functional class was the most dominant predictor among the somatic variables studied, the major determinants of reduced quality of life remain unknown. PMID:11847161

Health related quality of life in patients with congestive heart failure: comparison with other chronic diseases and relation to functional variables.

PubMed

Juenger, J; Schellberg, D; Kraemer, S; Haunstetter, A; Zugck, C; Herzog, W; Haass, M

2002-03-01

To assess health related quality of life of patients with congestive heart failure; to compare their quality of life with the previously characterised general population and in those with other chronic diseases; and to correlate the different aspects of quality of life with relevant somatic variables. University hospital. A German version of the generic quality of life measure (SF-36) containing eight dimensions was administered to 205 patients with congestive heart failure and systolic dysfunction. Cardiopulmonary evaluation included assessment of New York Heart Association (NYHA) functional class, left ventricular ejection fraction, peak oxygen uptake, and the distance covered during a standardised six minute walk test. Quality of life significantly decreased with NYHA functional class (linear trend: p < 0.0001). In NYHA class III, the scores of five of the eight quality of life domains were reduced to around one third of those in the general population. The pattern of reduction was different in patients with chronic hepatitis C and major depression, and similar in patients on chronic haemodialysis. Multiple regression analysis showed that only the NYHA functional class was consistently and closely associated with all quality of life scales. The six minute walk test and peak oxygen uptake added to the explanation of the variance in only one of the eight quality of life domains (physical functioning). Left ventricular ejection fraction, duration of disease, and age showed no clear association with quality of life. In congestive heart failure, quality of life decreases as NYHA functional class worsens. Though NYHA functional class was the most dominant predictor among the somatic variables studied, the major determinants of reduced quality of life remain unknown.

Metal-phthalocyanine functionalized carbon nanotubes as catalyst for the oxygen reduction reaction: A theoretical study

NASA Astrophysics Data System (ADS)

Orellana, Walter

2012-07-01

The covalent functionalization of metallic single-walled carbon nanotubes (CNTs) with transition metal phthalocyanines (MPc, with M = Mn, Fe and Co) are addressed by density functional calculations. The CNT-MPc catalytic activity toward the oxygen reduction reaction (ORR) is investigated through the O2 stretching frequency adsorbed on the phthalocyanine metal center. We find better reduction abilities when the CNT functionalization occurs through sp2-like bonds. Multiple stable-spin states for the M-O2 adduct are also found for M = Mn and Fe, suggesting higher ORR rates. The CNT-MPc complexes show metallic characteristics, suggesting favorable conditions to work as ORR cathode catalysts in fuel cells.

KOH-activated multi-walled carbon nanotubes as platinum supports for oxygen reduction reaction

NASA Astrophysics Data System (ADS)

He, Chaoxiong; Song, Shuqin; Liu, Jinchao; Maragou, Vasiliki; Tsiakaras, Panagiotis

In the present investigation, multi-walled carbon nanotubes (MWCNTs) thermally treated by KOH were adopted as the platinum supporting material for the oxygen reduction reaction electrocatalysts. FTIR and Raman spectra were used to investigate the surface state of MWCNTs treated by KOH at different temperatures (700, 800, and 900 °C) and showed MWCNTs can be successfully functionalized. The structural properties of KOH-activated MWCNTs supported Pt were determined by X-ray diffraction (XRD) and transmission electron microscopy (TEM), and their electrochemical performance was evaluated by the aid of cyclic voltammetry (CV) and rotating disk electrode (RDE) voltammetry. According to the experimental findings of the present work, the surrface of MWCNTs can be successfully functionalized with oxygen-containing groups after activation by KOH, favoring the good dispersion of Pt nanoparticles with narrow size distribution. The as-prepared Pt catalysts supported on KOH treated MWCNTs at higher temperature, possess higher electrochemical surface area and exhibit desirable activity towards oxygen reduction reaction (ORR). More precisely, it has been found that the electrochemical active area of Pt/MWCNTs-900 is approximately two times higher than that of Pt/MWCNTs. It can be concluded that KOH activation is an effective way to decorate MWCNTs' surface with oxygen-containing groups and bigger surface area, which makes them more suitable as electrocatalyst support materials.

PARALLEL ASSAY OF OXYGEN EQUILIBRIA OF HEMOGLOBIN

PubMed Central

Lilly, Laura E.; Blinebry, Sara K.; Viscardi, Chelsea M.; Perez, Luis; Bonaventura, Joe; McMahon, Tim J.

2013-01-01

Methods to systematically analyze in parallel the function of multiple protein or cell samples in vivo or ex vivo (i.e. functional proteomics) in a controlled gaseous environment have thus far been limited. Here we describe an apparatus and procedure that enables, for the first time, parallel assay of oxygen equilibria in multiple samples. Using this apparatus, numerous simultaneous oxygen equilibrium curves (OECs) can be obtained under truly identical conditions from blood cell samples or purified hemoglobins (Hbs). We suggest that the ability to obtain these parallel datasets under identical conditions can be of immense value, both to biomedical researchers and clinicians who wish to monitor blood health, and to physiologists studying non-human organisms and the effects of climate change on these organisms. Parallel monitoring techniques are essential in order to better understand the functions of critical cellular proteins. The procedure can be applied to human studies, wherein an OEC can be analyzed in light of an individual’s entire genome. Here, we analyzed intraerythrocytic Hb, a protein that operates at the organism’s environmental interface and then comes into close contact with virtually all of the organism’s cells. The apparatus is theoretically scalable, and establishes a functional proteomic screen that can be correlated with genomic information on the same individuals. This new method is expected to accelerate our general understanding of protein function, an increasingly challenging objective as advances in proteomic and genomic throughput outpace the ability to study proteins’ functional properties. PMID:23827235

Constitutive modeling of intrinsic and oxygen-contaminated silicon monocrystals in easy glide

NASA Astrophysics Data System (ADS)

Cochard, J.; Yonenaga, I.; Gouttebroze, S.; M'Hamdi, M.; Zhang, Z. L.

2010-11-01

We generalize in this work the constitutive model for silicon crystals of Alexander and Haasen. Strain-rate and temperature dependency of the mechanical behavior of intrinsic crystals are correctly accounted for into stage I of hardening. We show that the steady-state of deformation in stage I is very well reproduced in a wide range of temperature and strain rate. The case of extrinsic crystals containing high levels of dissolved oxygen is examined. The introduction of an effective density of mobile dislocations dependent on the unlocking stress created by oxygen atoms gathered at the dislocation cores is combined to an alteration of the dislocation multiplication rate, due to pinning of the dislocation line by oxygen atoms. This increases the upper yield stress with the bulk oxygen concentration in agreement with experimental observations. The fraction of effectively mobile dislocations is found to decay exponentially with the unlocking stress. Finally, the influence of oxygen migration back onto the dislocations from the bulk on the stress distribution in silicon bars is investigated.

High temperature volatility and oxidation measurements of titanium and silicon containing ceramic materials

NASA Astrophysics Data System (ADS)

Nguyen, Quynhgiao N.

Titanium (Ti) containing materials are of high interest to the aerospace industry due to its high temperature capability, strength, and light weight. As with most metals an exterior oxide layer naturally exists in environments that contain oxygen (i.e. air). At high temperatures, water vapor plays a key role in the volatility of materials including oxide surfaces. This study first evaluates several hot-pressed Ti-containing compositions at high temperatures as a function of oxidation resistance. This study will also evaluate cold pressed titanium dioxide (TiO2) powder pellets at a temperature range of 1400°C--1200°C in water containing environments to determine the volatile hydoxyl species using the transpiration method. The water content ranged from 0-76 mole % and the oxygen content range was 0-100 mole % during the 20-250 hour exposure times. Preliminary results indicate that oxygen is not a key contributor at these temperatures and the following reaction is the primary volatile equation at all three temperatures: TiO 2 (s) + H2O (g) = TiO(OH)2 (g).

Frequency bandwidth extension by use of multiple Zeeman field offsets for electron spin-echo EPR oxygen imaging of large objects

PubMed Central

Seifi, Payam; Epel, Boris; Sundramoorthy, Subramanian V.; Mailer, Colin; Halpern, Howard J.

2011-01-01

Purpose: Electron spin-echo (ESE) oxygen imaging is a new and evolving electron paramagnetic resonance (EPR) imaging (EPRI) modality that is useful for physiological in vivo applications, such as EPR oxygen imaging (EPROI), with potential application to imaging of multicentimeter objects as large as human tumors. A present limitation on the size of the object to be imaged at a given resolution is the frequency bandwidth of the system, since the location is encoded as a frequency offset in ESE imaging. The authors’ aim in this study was to demonstrate the object size advantage of the multioffset bandwidth extension technique.Methods: The multiple-stepped Zeeman field offset (or simply multi-B) technique was used for imaging of an 8.5-cm-long phantom containing a narrow single line triaryl methyl compound (trityl) solution at the 250 MHz imaging frequency. The image is compared to a standard single-field ESE image of the same phantom.Results: For the phantom used in this study, transverse relaxation (T2e) electron spin-echo (ESE) images from multi-B acquisition are more uniform, contain less prominent artifacts, and have a better signal to noise ratio (SNR) compared to single-field T2e images.Conclusions: The multi-B method is suitable for imaging of samples whose physical size restricts the applicability of the conventional single-field ESE imaging technique. PMID:21815379

Structure, temperature and frequency dependent electrical conductivity of oxidized and reduced electrochemically exfoliated graphite

NASA Astrophysics Data System (ADS)

Radoń, Adrian; Włodarczyk, Patryk; Łukowiec, Dariusz

2018-05-01

The article presents the influence of reduction by hydrogen in statu nascendi and modification by hydrogen peroxide on the structure and electrical conductivity of electrochemically exfoliated graphite. It was confirmed that the electrochemical exfoliation can be used to produce oxidized nanographite with an average number of 25 graphene layers. The modified electrochemical exfoliated graphite and reduced electrochemical exfoliated graphite were characterized by high thermal stability, what was associated with removing of labile oxygen-containing groups. The presence of oxygen-containing groups was confirmed using Fourier-transform infrared spectroscopy. Influence of chemical modification by hydrogen and hydrogen peroxide on the electrical conductivity was determined in wide frequency (0.1 Hz-10 kHz) and temperature range (-50 °C-100 °C). Material modified by hydrogen peroxide (0.29 mS/cm at 0 °C) had the lowest electrical conductivity. This can be associated with oxidation of unstable functional groups and was also confirmed by analysis of Raman spectra. The removal of oxygen-containing functional groups by hydrogen in statu nascendi resulted in a 1000-fold increase in the electrical conductivity compared to the electrochemical exfoliated graphite.

Polystyrene Foam Products Equation of State as a Function of Porosity and Fill Gas

NASA Astrophysics Data System (ADS)

Mulford, R. N.; Swift, D. C.

2009-12-01

An accurate EOS for polystyrene foam is necessary for analysis of numerous experiments in shock compression, inertial confinement fusion, and astrophysics. Plastic to gas ratios vary between various samples of foam, according to the density and cell-size of the foam. A matrix of compositions has been investigated, allowing prediction of foam response as a function of the plastic-to-air ratio. The EOS code CHEETAH allows participation of the air in the decomposition reaction of the foam. Differences between air-filled, Ar-blown, and CO2-blown foams are investigated, to estimate the importance of allowing air to react with products of polystyrene decomposition. O2-blown foams are included in some comparisons, to amplify any consequences of reaction with oxygen in air. He-blown foams are included in some comparisons, to provide an extremum of density. Product pressures are slightly higher for oxygen-containing fill gases than for non-oxygen-containing fill gases. Examination of product species indicates that CO2 decomposes at high temperatures.

Optimization and application of atmospheric pressure chemical and photoionization hydrogen-deuterium exchange mass spectrometry for speciation of oxygen-containing compounds.

PubMed

Acter, Thamina; Kim, Donghwi; Ahmed, Arif; Jin, Jang Mi; Yim, Un Hyuk; Shim, Won Joon; Kim, Young Hwan; Kim, Sunghwan

2016-05-01

This paper presents a detailed investigation of the feasibility of optimized positive and negative atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) and atmospheric pressure photoionization (APPI) MS coupled to hydrogen-deuterium exchange (HDX) for structural assignment of diverse oxygen-containing compounds. The important parameters for optimization of HDX MS were characterized. The optimized techniques employed in the positive and negative modes showed satisfactory HDX product ions for the model compounds when dichloromethane and toluene were employed as a co-solvent in APCI- and APPI-HDX, respectively. The evaluation of the mass spectra obtained from 38 oxygen-containing compounds demonstrated that the extent of the HDX of the ions was structure-dependent. The combination of information provided by different ionization techniques could be used for better speciation of oxygen-containing compounds. For example, (+) APPI-HDX is sensitive to compounds with alcohol, ketone, or aldehyde substituents, while (-) APPI-HDX is sensitive to compounds with carboxylic functional groups. In addition, the compounds with alcohol can be distinguished from other compounds by the presence of exchanged peaks. The combined information was applied to study chemical compositions of degraded oils. The HDX pattern, double bond equivalent (DBE) distribution, and previously reported oxidation products were combined to predict structures of the compounds produced from oxidation of oil. Overall, this study shows that APCI- and APPI-HDX MS are useful experimental techniques that can be applied for the structural analysis of oxygen-containing compounds.

The hemoglobin system of the primitive fish, Amia calva: isolation and functional characterization of the individual hemoglobin components.

PubMed

Weber, R E; Sullivan, B; Bonaventura, J; Bonaventura, C

1976-05-20

Blood from the primitive holostean fish, the bowfin, Amia calva, contains 2 mo of ATP per mol of hemoglobin. The hemolysates contain at least five tetrameric hemoglobin components which differ in their oxygen affinities and their response to cofactors such as ATP. The binding of oxygen by each chromatographically isolated component, including a cathodal component, is influenced by pH and organic phosphates; there is no significant differentiation of function or structure as seen in trout and certain other fish hemolysates. Kinetic analyses of ligand binding indicate that the Bohr and Root effects of Amia calva hemoglobins are best explained by changes in both the "on" and "off" constants. At low pH, the increase in the "off" constant is smaller than for most other Root hemoglobins. The hemoglobin system of Amina calva is functionally undifferentiated and may be representative of the ancestral condition in teleosts.

Investigating the sorption behavior of cadmium from aqueous solution by potassium permanganate-modified biochar: quantify mechanism and evaluate the modification method.

PubMed

Fan, Zixi; Zhang, Qian; Li, Meng; Niu, Dongyuan; Sang, Wenjiao; Verpoort, Francis

2018-03-01

In this work, a KMnO 4 -modified-biochar-based composite material with manganese oxide produced at 600 °C was fabricated to investigate the sorption mechanism of Cd(II) and to comprehensively evaluate the effect of the modification on biochar properties. Cd(II) adsorption mechanisms were mainly controlled by interaction with minerals, complexation with oxygen-containing functional groups, and cation-π interaction. The sorption capacity was significantly reduced after a deash treatment of biochar, almost shrunk by 3 and 3.5 times for pristine biochar (PBC) and modified biochar (MBC). For deashed PBC, oxygen-containing functional groups were the main contributor toward Cd(II) adsorption while interaction with minerals was significantly compromised and became negligible. The sorption capacity was also apparently decreased after the deash treatment of MBC; however, for deashed MBC, interaction with minerals still was the main contributor to the sorption ability, which could be attributed to the mechanism of interaction of Cd(II) with loaded MnO x on biochar. Cation-π interaction in MBC was notably enhanced compared to PBC due to the oxidation of KMnO 4 on biomass. Also, sorption performance by oxygen-containing functional groups was also enhanced. Hence, the modification by KMnO 4 has a significant effect on the Cd(II) sorption performance of biochar.

Influence of surface oxides on the adsorption of naphthalene onto multiwalled carbon nanotubes.

PubMed

Cho, Hyun-Hee; Smith, Billy A; Wnuk, Joshua D; Fairbrother, D Howard; Ball, William P

2008-04-15

As greater quantities of carbon nanotubes (CNTs) enter the environment, they will have an increasingly important effect on the availability and transport of aqueous contaminants. As a consequence of purification, deliberate surface functionalization, and/or exposure to oxidizing agents after release to the environment, CNTs often contain surface oxides (i.e., oxygen containing functional groups). To probe the influence that surface oxides exert on CNT sorption properties, multiwalled CNTs (MWCNTs) with varying oxygen concentrations were studied with respect to their sorption properties toward naphthalene. For pristine (as-received) MWCNTs, the sorption capacity was intermediate between that of a natural char and a granular activated carbon. Sorption data also reveal that a linear relationship exists between the oxygen content of MWCNTs and their maximum adsorption capacity for naphthalene, with 10% surface oxygen concentration resulting in a roughly 70% decrease in maximum adsorption capacity. The relative distribution of sorption energies, as characterized by Freundlich isotherm exponents was, however, unaffected by oxidation. Thus, the data are consistent with the idea that incorporated surface oxides create polar regions that reduce the surface area available for naphthalene sorption. These results highlight the important role of surface chemistry in controlling the environmental properties of CNTs.

Detection of Cyclooxygenase-2-Derived Oxygenation Products of the Endogenous Cannabinoid 2-Arachidonoylglycerol in Mouse Brain.

PubMed

Morgan, Amanda J; Kingsley, Philip J; Mitchener, Michelle M; Altemus, Megan; Patrick, Toni A; Gaulden, Andrew D; Marnett, Lawrence J; Patel, Sachin

2018-05-09

Cyclooxygenase-2 (COX-2) catalyzes the formation of prostaglandins, which are involved in immune regulation, vascular function, and synaptic signaling. COX-2 also inactivates the endogenous cannabinoid (eCB) 2-arachidonoylglycerol (2-AG) via oxygenation of its arachidonic acid backbone to form a variety of prostaglandin glyceryl esters (PG-Gs). Although this oxygenation reaction is readily observed in vitro and in intact cells, detection of COX-2-derived 2-AG oxygenation products has not been previously reported in neuronal tissue. Here we show that 2-AG is metabolized in the brain of transgenic COX-2-overexpressing mice and mice treated with lipopolysaccharide to form multiple species of PG-Gs that are detectable only when monoacylglycerol lipase is concomitantly blocked. Formation of these PG-Gs is prevented by acute pharmacological inhibition of COX-2. These data provide evidence that neuronal COX-2 is capable of oxygenating 2-AG to form a variety PG-Gs in vivo and support further investigation of the physiological functions of PG-Gs.

Temporal and Spatial Variability of the Martian Hot Oxygen Corona

NASA Astrophysics Data System (ADS)

Deighan, J.; Jain, S.; Chaffin, M.; Chaufray, J. Y.; Schneider, N. M.; Clarke, J. T.; Mayyasi, M.; Lillis, R. J.; Eparvier, F. G.; Thiemann, E.; Chamberlin, P. C.

2017-12-01

The dominant loss mechanism of oxygen from Mars to space in the current epoch is thought to be photochemical escape of hot oxygen produced by dissociative recombination of O2+. This ion is ultimately sourced from CO2+, which is the primary product of photoionization. The escaping hot oxygen population is accompanied by a gravitationally bound hot oxygen corona produced by the same mechanism. The MAVEN spacecraft has been at Mars since November 2014, with multiple seasons suitable for the IUVS instrument to observe the dayside hot oxygen corona via fluorescence of the O I 130.4 nm triplet. This provides the opportunity to examine temporal variations associated with changes in the photoionizing solar EUV radiation which produces CO2+ and O2+ ions. We present results based on two seasons: LS = 270 in Mars Year 32 during the maximum of Solar Cycle 24 and LS = 210 in Mars Year 33 late in the declining phase of the same Solar Cycle. The data in both seasons contain multiple solar rotations. We compare the oxygen corona density to the EUV solar flux measured by MAVEN/EUVM and ionization frequencies calculated therefrom. The peak brightness of ionospheric CO2+ UVD emission from IUVS limb scans is also used as a direct indicator of the photoionization frequency. As expected, the result is a strong correlation between solar EUV input, observed ionization frequency, and the density of the hot oxygen corona. In addition, a new observation strategy was employed during the MY 33 season to view the Martian corona near the sub-solar point with anti-parallel lines of sight from opposing hemispheres. These observations reveal a significant hemispherical asymmetry in brightness, providing a constraint on the large scale spatial variability of the dayside oxygen corona.

Catalytic Arylation and Vinylation Reactions Directed by Anionic Oxygen Functions via Cleavage of C - H and C - C Bonds

NASA Astrophysics Data System (ADS)

Satoh, Tetsuya; Miura, Masahiro

Aromatic compounds having oxygen-containing substituents such as phenols, phenyl ketones, benzyl alcohols, and benzoic acids undergo regioselective arylation and vinylation via C-H bond cleavage in the presence of transition-metal catalysts. The latter two substrates are also arylated and vinylated via C-C bond cleavage accompanied by liberation of ketones and CO2, respectively. Coordination of their anionic oxygen to the metal center is the key to activate the inert bonds effectively and regioselectively. The recent progress of these oxygen-directed reactions is summarized herein.

Effectiveness of acidic oxidative potential water in preventing bacterial infection in islet transplantation.

PubMed

Miyamoto, M; Inoue, K; Gu, Y; Hoki, M; Haji, S; Ohyanagi, H

1999-01-01

At a number of points in the current procedures of islet isolation and islet culture after the harvesting of donor pancreata, microorganisms could potentially infect the islet preparation. Furthermore, the use of islets from multiple donors can compound the risks of contamination of individual recipients. Acidic oxidative potential water (also termed electrolyzed strong acid solution, function water, or acqua oxidation water), which was developed in Japan, is a strong acid formed on the anode in the electrolysis of water containing a small amount of sodium chloride. It has these physical properties: pH, from 2.3 to 2.7; oxidative-reduction potential, from 1,000 to 1,100 mV; dissolved chlorine, from 30 to 40 ppm; and dissolved oxygen, from 10 to 30 ppm. Because of these properties, acidic oxidative potential water has strong bactericidal effects on all bacteria including methicillin-resistant Staphylococcus aureus (MRSA), viruses including HIV, HBV, HCV, CMV, and fungi as a result of the action of the active oxygen and active chlorine that it contains. We conducted this study to evaluate the effect of acidic oxidative potential water irrigation on bacterial contamination on the harvesting of porcine pancreata from slaughterhouses for islet xenotransplantation by counting the number of pancreatic surface bacteria using the Dip-slide method, and on the results of islet culture; and to evaluate the direct effect on isolated islets when it is used to prevent bacterial contamination by the static incubation test and by morphological examination. Direct irrigation of the pancreas by acidic oxidative potential water was found to be very effective in preventing bacterial contamination, but direct irrigation of isolated islets slightly decreased their viability and function.

Recent advances on edible films based on fruit and vegetables- a review

USDA-ARS?s Scientific Manuscript database

A food packaging system has different functions, including those related to containment, information, and marketing. However, its primary function is to separate food from the surrounding environment, reducing food exposure to deteriorating factors such as microorganisms, oxygen, water vapor, off-fl...

Mechanism of organic aerosol formation and aging: Role of the precursor carbon skeleton

NASA Astrophysics Data System (ADS)

Hunter, J. F.; Carrasquillo, A. J.; Daumit, K. E.; Cross, E. S.; Worsnop, D. R.; Kroll, J. H.

2012-12-01

Oxidative aging of organic aerosol consists of a complex set of reactions coupled with gas-particle partitioning processes. Functionalization reactions involve adding oxygen containing functional groups onto a molecule, leading to reduced vapor pressures and promoting aerosol formation. In fragmentation reactions carbon-carbon bonds are broken as oxygen containing functional groups are added, which generally splits the parent molecule into two smaller and more volatile products. The initial structure of an aerosol-forming precursor molecule may influence what chemistry will occur both by changing the branching between fragmentation and functionalization processes as well as changing the effects of those processes. The fate of early generation oxidation products upon further aging is dependent on this initial chemistry, leading to a persistent effect of the precursor carbon skeleton. Aging experiments have been conducted using a high NOx smog chamber based aging technique. Long residence times and modestly elevated OH concentrations lead to typical maximum OH exposure of 3e11 molecule*seconds/cc, approaching several days equivalent exposure to ambient OH concentrations. A broad set of linear, branched and cyclic aliphatic hydrocarbons has been oxidized to determine the effects of carbon skeleton on the relative importance of fragmentation and functionalization and impacts on aerosol formation chemistry. Relative degree of fragmentation and functionalization is constrained by mass spectrometry of both the gas and particle phase. Measurements of the aerosol oxygen content and mass yield are reported, and structural effects on these properties are determined. Degree of unsaturation is hypothesized to have a significant impact on the effect of fragmentation reactions and to promote additional aerosol formation, extended aging and more oxygenated aerosol.

Manipulating multiple order parameters via oxygen vacancies: The case of E u0.5B a0.5Ti O3 -δ

NASA Astrophysics Data System (ADS)

Li, Weiwei; He, Qian; Wang, Le; Zeng, Huizhong; Bowlan, John; Ling, Langsheng; Yarotski, Dmitry A.; Zhang, Wenrui; Zhao, Run; Dai, Jiahong; Gu, Junxing; Shen, Shipeng; Guo, Haizhong; Pi, Li; Wang, Haiyan; Wang, Yongqiang; Velasco-Davalos, Ivan A.; Wu, Yangjiang; Hu, Zhijun; Chen, Bin; Li, Run-Wei; Sun, Young; Jin, Kuijuan; Zhang, Yuheng; Chen, Hou-Tong; Ju, Sheng; Ruediger, Andreas; Shi, Daning; Borisevich, Albina Y.; Yang, Hao

2017-09-01

Controlling functionalities, such as magnetism or ferroelectricity, by means of oxygen vacancies (VO) is a key issue for the future development of transition-metal oxides. Progress in this field is currently addressed through VO variations and their impact on mainly one order parameter. Here we reveal a mechanism for tuning both magnetism and ferroelectricity simultaneously by using VO. Combining experimental and density-functional theory studies of E u0.5B a0.5Ti O3 -δ , we demonstrate that oxygen vacancies create T i3 +3 d1 defect states, mediating the ferromagnetic coupling between the localized Eu 4 f7 spins, and increase an off-center displacement of Ti ions, enhancing the ferroelectric Curie temperature. The dual function of Ti sites also promises a magnetoelectric coupling in the E u0.5B a0.5Ti O3 -δ .

Calcium-manganese oxides as structural and functional models for active site in oxygen evolving complex in photosystem II: lessons from simple models.

PubMed

Najafpour, Mohammad Mahdi

2011-01-01

The oxygen evolving complex in photosystem II which induces the oxidation of water to dioxygen in plants, algae and certain bacteria contains a cluster of one calcium and four manganese ions. It serves as a model to split water by sunlight. Reports on the mechanism and structure of photosystem II provide a more detailed architecture of the oxygen evolving complex and the surrounding amino acids. One challenge in this field is the development of artificial model compounds to study oxygen evolution reaction outside the complicated environment of the enzyme. Calcium-manganese oxides as structural and functional models for the active site of photosystem II are explained and reviewed in this paper. Because of related structures of these calcium-manganese oxides and the catalytic centers of active site of the oxygen evolving complex of photosystem II, the study may help to understand more about mechanism of oxygen evolution by the oxygen evolving complex of photosystem II. Copyright © 2010 Elsevier B.V. All rights reserved.

Coexistence of multiple globin genes conferring protection against nitrosative stress to the Antarctic bacterium Pseudoalteromonas haloplanktis TAC125.

PubMed

Coppola, Daniela; Giordano, Daniela; Milazzo, Lisa; Howes, Barry D; Ascenzi, Paolo; di Prisco, Guido; Smulevich, Giulietta; Poole, Robert K; Verde, Cinzia

2018-02-28

Despite the large number of globins recently discovered in bacteria, our knowledge of their physiological functions is restricted to only a few examples. In the microbial world, globins appear to perform multiple roles in addition to the reversible binding of oxygen; all these functions are attributable to the heme pocket that dominates functional properties. Resistance to nitrosative stress and involvement in oxygen chemistry seem to be the most prevalent functions for bacterial globins, although the number of globins for which functional roles have been studied via mutation and genetic complementation is very limited. The acquisition of structural information has considerably outpaced the physiological and molecular characterisation of these proteins. The genome of the Antarctic cold-adapted bacterium Pseudoalteromonas haloplanktis TAC125 (PhTAC125) contains genes encoding three distinct single-chain 2/2 globins, supporting the hypothesis of their crucial involvement in a number of functions, including protection against oxidative and nitrosative stress in the cold and O 2 -rich environment. In the genome of PhTAC125, the genes encoding 2/2 globins are constitutively transcribed, thus suggesting that these globins are not functionally redundant in their physiological function in PhTAC125. In the present study, the physiological role of one of the 2/2 globins, Ph-2/2HbO-2217, was investigated by integrating in vivo and in vitro results. This role includes the involvement in the detoxification of reactive nitrogen and O 2 species including NO by developing two in vivo and in vitro models to highlight the protective role of Ph-2/2HbO-2217 against reactive nitrogen species. The PSHAa2217 gene was cloned and over-expressed in the flavohemoglobin-deficient mutant of Escherichia coli and the growth properties and O 2 uptake in the presence of NO of the mutant carrying the PSHAa2217 gene were analysed. The ferric form of Ph-2/2HbO-2217 is able to catalyse peroxynitrite isomerisation in vitro, indicating its potential role in the scavenging of reactive nitrogen species. Here we present in vitro evidence for the detoxification of NO by Ph-2/2HbO-2217. Copyright © 2017. Published by Elsevier Inc.

Interplay between oxygen and Fe-S cluster biogenesis: insights from the Suf pathway.

PubMed

Boyd, Eric S; Thomas, Khaleh M; Dai, Yuyuan; Boyd, Jeff M; Outten, F Wayne

2014-09-23

Iron-sulfur (Fe-S) cluster metalloproteins conduct essential functions in nearly all contemporary forms of life. The nearly ubiquitous presence of Fe-S clusters and the fundamental requirement for Fe-S clusters in both aerobic and anaerobic Archaea, Bacteria, and Eukarya suggest that these clusters were likely integrated into central metabolic pathways early in the evolution of life prior to the widespread oxidation of Earth's atmosphere. Intriguingly, Fe-S cluster-dependent metabolism is sensitive to disruption by oxygen because of the decreased bioavailability of ferric iron as well as direct oxidation of sulfur trafficking intermediates and Fe-S clusters by reactive oxygen species. This fact, coupled with the ubiquity of Fe-S clusters in aerobic organisms, suggests that organisms evolved with mechanisms that facilitate the biogenesis and use of these essential cofactors in the presence of oxygen, which gradually began to accumulate around 2.5 billion years ago as oxygenic photosynthesis proliferated and reduced minerals that buffered against oxidation were depleted. This review highlights the most ancient of the Fe-S cluster biogenesis pathways, the Suf system, which likely was present in early anaerobic forms of life. Herein, we use the evolution of the Suf pathway to assess the relationships between the biochemical functions and physiological roles of Suf proteins, with an emphasis on the selective pressure of oxygen toxicity. Our analysis suggests that diversification into oxygen-containing environments disrupted iron and sulfur metabolism and was a main driving force in the acquisition of accessory Suf proteins (such as SufD, SufE, and SufS) by the core SufB-SufC scaffold complex. This analysis provides a new framework for the study of Fe-S cluster biogenesis pathways and Fe-S cluster-containing metalloenzymes and their complicated patterns of divergence in response to oxygen.

Novel durable bio-photocatalyst purifiers, a non-heterogeneous mechanism: accelerated entrapped dye degradation into structural polysiloxane-shield nano-reactors.

PubMed

Dastjerdi, Roya; Montazer, Majid; Shahsavan, Shadi; Böttcher, Horst; Moghadam, M B; Sarsour, Jamal

2013-01-01

This research has designed innovative Ag/TiO(2) polysiloxane-shield nano-reactors on the PET fabric to develop novel durable bio-photocatalyst purifiers. To create these very fine nano-reactors, oppositely surface charged multiple size nanoparticles have been applied accompanied with a crosslinkable amino-functionalized polysiloxane (XPs) emulsion. Investigation of photocatalytic dye decolorization efficiency revealed a non-heterogeneous mechanism including an accelerated degradation of entrapped dye molecules into the structural polysiloxane-shield nano-reactors. In fact, dye molecules can be adsorbed by both Ag and XPs due to their electrostatic interactions and/or even via forming a complex with them especially with silver NPs. The absorbed dye and active oxygen species generated by TiO(2) were entrapped by polysiloxane shelter and the presence of silver nanoparticles further attract the negative oxygen species closer to the adsorbed dye molecules. In this way, the dye molecules are in close contact with concentrated active oxygen species into the created nano-reactors. This provides an accelerated degradation of dye molecules. This non-heterogeneous mechanism has been detected on the sample containing all of the three components. Increasing the concentration of Ag and XPs accelerated the second step beginning with an enhanced rate. Further, the treated samples also showed an excellent antibacterial activity. Copyright © 2012 Elsevier B.V. All rights reserved.

Oxygen analyzer

DOEpatents

Benner, William H.

1986-01-01

An oxygen analyzer which identifies and classifies microgram quantities of oxygen in ambient particulate matter and for quantitating organic oxygen in solvent extracts of ambient particulate matter. A sample is pyrolyzed in oxygen-free nitrogen gas (N.sub.2), and the resulting oxygen quantitatively converted to carbon monoxide (CO) by contact with hot granular carbon (C). Two analysis modes are made possible: (1) rapid determination of total pyrolyzable oxygen obtained by decomposing the sample at 1135.degree. C., or (2) temperature-programmed oxygen thermal analysis obtained by heating the sample from room temperature to 1135.degree. C. as a function of time. The analyzer basically comprises a pyrolysis tube containing a bed of granular carbon under N.sub.2, ovens used to heat the carbon and/or decompose the sample, and a non-dispersive infrared CO detector coupled to a mini-computer to quantitate oxygen in the decomposition products and control oven heating.

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

Estevez, Luis; Reed, David; Nie, Zimin

We decorated the surfaces of graphite felts with some oxygen-containing functional groups, such as C-OH, O=C and HO-C=O. And the mole ratios and amounts of these functional groups were effectively adjusted on the graphite surface by a particular method. The catalytic effects of amounts and mole ratio of different kinds of functional groups on VRB electrode performances were investigated in detail.

Use of impure inert gases in the controlled heating and cooling of mixed conducting metal oxide materials

DOEpatents

Carolan, Michael Francis [Allentown, PA; Bernhart, John Charles [Fleetwood, PA

2012-08-21

Method for processing an article comprising mixed conducting metal oxide material. The method comprises contacting the article with an oxygen-containing gas and either reducing the temperature of the oxygen-containing gas during a cooling period or increasing the temperature of the oxygen-containing gas during a heating period; during the cooling period, reducing the oxygen activity in the oxygen-containing gas during at least a portion of the cooling period and increasing the rate at which the temperature of the oxygen-containing gas is reduced during at least a portion of the cooling period; and during the heating period, increasing the oxygen activity in the oxygen-containing gas during at least a portion of the heating period and decreasing the rate at which the temperature of the oxygen-containing gas is increased during at least a portion of the heating period.

Brain Vulnerability to Repeated Blast Overpressure and Polytrauma

DTIC Science & Technology

2015-10-01

characterization of the mouse model of repeated blast also found no cumula- tive effect of repeated blast on cortical levels of reactive oxygen species [39]. C...overpressure in rats to investigate the cumulative effects of multiple blast exposures on neurologic status, neurobehavioral function, and brain...preclinical model of blast overpressure in rats to investigate the cumulative effects of multiple blast exposures using neurological, neurochemical

Whey protein film with oxygen scavenging function by incorporation of ascorbic acid.

PubMed

Janjarasskul, Theeranun; Tananuwong, Kanitha; Krochta, John M

2011-01-01

Residual O(2) in a package headspace can be removed by an O(2)-absorbing sachet, which can be harmful if swallowed by the consumer, or by a chemically-active plastic packaging film, which is difficult to recycle. An edible, O(2)-absorbing film would avoid these disadvantages. The objective of our research was to assess the O(2)-scavenging potential of an edible whey protein isolate (WPI) film incorporating ascorbic acid (AA). AA at 0.05, 0.1, or 0.2 M was added to 5% (w/w) heat-denatured WPI film-forming solutions with WPI : glycerol (Gly) ratio of 1: 1.00, 1: 0.80, or 1: 0.67. The pH of solutions was then adjusted to 3.5 (below pK(a1) of AA), to stabilize AA against oxidation, before film casting. The mechanical properties, O(2) permeabilities, and thermal transitions of films were measured. Activation of the O(2)-scavenging function of the AA-incorporated films was accomplished by adjustment of the films to pH ≥ 7. O(2)-scavenging ability of AA-incorporated WPI films was determined by measuring residual O(2) in the headspace of a high-barrier container. Incorporation of AA into WPI film decreased film tensile strength and further reduced O(2) permeability at each WPI : Gly ratio. AA-containing films adjusted to pH ≥ 7 demonstrated O(2) absorption proportional to AA content, consistent with theoretical O(2)-scavenging capacity. Thermal transition measurements indicated that AA was involved in WPI structural modification and decreased the degradation temperature of WPI-based film. The demonstrated O(2)-scavenging function, improved O(2) barrier and acceptable mechanical properties of AA-incorporated films indicate potential commercial usefulness. Ascorbic acid-incorporated whey protein film with oxygen scavenging function can be used to extend shelf lives of a wide variety of oxygen-sensitive products by eliminating headspace oxygen as well as oxygen permeating through the packaging wall over time. Edible oxygen-scavenger film has the advantages of avoiding both accidental consumption and nonrecyclability of conventional oxygen scavenger systems. © 2011 Institute of Food Technologists®

The Electrosome: A Surface-Displayed Enzymatic Cascade in a Biofuel Cell’s Anode and a High-Density Surface-Displayed Biocathodic Enzyme

PubMed Central

Szczupak, Alon; Aizik, Dror; Moraïs, Sarah; Vazana, Yael; Barak, Yoav; Bayer, Edward A.; Alfonta, Lital

2017-01-01

The limitation of surface-display systems in biofuel cells to a single redox enzyme is a major drawback of hybrid biofuel cells, resulting in a low copy-number of enzymes per yeast cell and a limitation in displaying enzymatic cascades. Here we present the electrosome, a novel surface-display system based on the specific interaction between the cellulosomal scaffoldin protein and a cascade of redox enzymes that allows multiple electron-release by fuel oxidation. The electrosome is composed of two compartments: (i) a hybrid anode, which consists of dockerin-containing enzymes attached specifically to cohesin sites in the scaffoldin to assemble an ethanol oxidation cascade, and (ii) a hybrid cathode, which consists of a dockerin-containing oxygen-reducing enzyme attached in multiple copies to the cohesin-bearing scaffoldin. Each of the two compartments was designed, displayed, and tested separately. The new hybrid cell compartments displayed enhanced performance over traditional biofuel cells; in the anode, the cascade of ethanol oxidation demonstrated higher performance than a cell with just a single enzyme. In the cathode, a higher copy number per yeast cell of the oxygen-reducing enzyme copper oxidase has reduced the effect of competitive inhibition resulting from yeast oxygen consumption. This work paves the way for the assembly of more complex cascades using different enzymes and larger scaffoldins to further improve the performance of hybrid cells. PMID:28644390

Lung vital capacity and oxygen saturation in adults with cerebral palsy

PubMed Central

Lampe, Renée; Blumenstein, Tobias; Turova, Varvara; Alves-Pinto, Ana

2014-01-01

Background Individuals with infantile cerebral palsy have multiple disabilities. The most conspicuous syndrome being investigated from many aspects is motor movement disorder with a spastic gait pattern. The lung function of adults with spasticity attracts less attention in the literature. This is surprising because decreased thoracic mobility and longstanding scoliosis should have an impact on lung function. With increasing age and the level of disability, individuals become susceptible to lung infections and reflux illness, and these are accompanied by increased aspiration risk. This study examined, with different methods, to what extent adults with congenital cerebral palsy and acquired spastic paresis – following traumatic brain injury – showed restriction of lung function. It also assessed the contribution of disability level on this restriction. Methods The oxygen saturation of 46 adults with a diagnosis of cerebral palsy was measured with an oximeter. Lung vital capacity was measured with a mobile spirometer and excursion of the thorax was clinically registered. The gross motor function levels and the presence or absence of scoliosis were determined. Results A significantly positive correlation between lung vital capacity and chest expansion was established. Both the lung vital capacity and the thorax excursion decreased with increases in gross motor function level. Oxygen saturation remained within the normal range in all persons, in spite of reduced values of the measured lung parameters. No statistically significant dependency between lung vital capacity and oxygen saturation, and between chest expansion and oxygen saturation was found. The scoliotic deformities of the spine were associated with an additional decrease in the vital capacity, but this did not affect blood oxygen supply. Conclusion Despite the decreased chest expansion and the significantly reduced lung volume in adults with cerebral palsy, sufficient oxygen supply was registered. PMID:25525345

Polystyrene foam products equation of state as a function of porosity and fill gas

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

Mulford, Roberta N; Swift, Damian C

2009-01-01

An accurate EOS for polystyrene foam is necessary for analysis of numerous experiments in shock compression, inertial confinement fusion, and astrophysics. Plastic to gas ratios vary between various samples of foam, according to the density and cell-size of the foam. A matrix of compositions has been investigated, allowing prediction of foam response as a function of the plastic-to-air ratio. The EOS code CHEETAH allows participation of the air in the decomposition reaction of the foam. Differences between air-filled, Ar-blown, and CO{sub 2}-blown foams are investigated, to estimate the importance of allowing air to react with products of polystyrene decomposition. O{submore » 2}-blown foams are included in some comparisons, to amplify any consequences of reaction with oxygen in air. He-blown foams are included in some comparisons, to provide an extremum of density. Product pressures are slightly higher for oxygen-containing fill gases than for non-oxygen-containing fill gases. Examination of product species indicates that CO{sub 2} decomposes at high temperatures.« less

Aerobic capacity explains physical functioning and participation in patients with multiple sclerosis-related fatigue.

PubMed

Rosalie Driehuis, Emma; van den Akker, Lizanne Eva; de Groot, Vincent; Beckerman, Heleen

2018-02-13

To investigate whether aerobic capacity explains the level of self-reported physical activity, physical functioning, and participation and autonomy in daily living in persons with multiple sclerosis-related fatigue. A cross-sectional study. Sixty-two participants with multiple sclerosis-related fatigue. Aerobic capacity was measured with a leg ergometer and was expressed as maximal oxygen uptake (VO2max, in ml/kg/min). Physical activity was measured with the Physical Activity Scale for Individuals with Physical Disabilities (PASIPD), physical functioning with the Short Form 36 - physical functioning (SF36-pf), and participation and autonomy in daily living with the Impact on Participation and Autonomy questionnaire (IPA). Multiple regression analyses were performed, adjusted for potential confounders (gender, age, body mass index, educational level, and employment status). Mean maximal oxygen uptake (VO2max) was 23.9 ml/kg/min (standard deviation (SD) 6.3 ml/kg/min). There was no significant relationship between VO2max and physical activity (PASIPD): β = 0.320, 95% confidence interval (95% CI) = -0.109 to 0.749, R2 = 10.8%. Higher VO2max correlated with better physical functioning (SF36-pf): β = 1.527, 95% CI = 0.820-2.234, R2 = 25.9%, and was significantly related to IPA domains "autonomy indoors" (β = -0.043, 95% CI = -0.067 to -0.020, R2 = 20.6%), "autonomy outdoors" (β = -0.037, 95% CI = -0.062 to -0.012, R2 = 18.2%) and "social life and relationships" (β=-0.033, 95% CI = -0.060 to -0.007, R2 = 21.3%). Maximum aerobic capacity was severely reduced in persons with multiple sclerosis-related fatigue. This partly explains the limited physical functioning and restrictions in participation and autonomy indoors, outdoors and in social life and relationships in these persons.

Oxygen analyzer

DOEpatents

Benner, W.H.

1984-05-08

An oxygen analyzer which identifies and classifies microgram quantities of oxygen in ambient particulate matter and for quantitating organic oxygen in solvent extracts of ambient particulate matter. A sample is pyrolyzed in oxygen-free nitrogen gas (N/sub 2/), and the resulting oxygen quantitatively converted to carbon monoxide (CO) by contact with hot granular carbon (C). Two analysis modes are made possible: (1) rapid determination of total pyrolyzable obtained by decomposing the sample at 1135/sup 0/C, or (2) temperature-programmed oxygen thermal analysis obtained by heating the sample from room temperature to 1135/sup 0/C as a function of time. The analyzer basically comprises a pyrolysis tube containing a bed of granular carbon under N/sub 2/, ovens used to heat the carbon and/or decompose the sample, and a non-dispersive infrared CO detector coupled to a mini-computer to quantitate oxygen in the decomposition products and control oven heating.

Oxygen-producing inert anodes for SOM process

DOEpatents

Pal, Uday B

2014-02-25

An electrolysis system for generating a metal and molecular oxygen includes a container for receiving a metal oxide containing a metallic species to be extracted, a cathode positioned to contact a metal oxide housed within the container; an oxygen-ion-conducting membrane positioned to contact a metal oxide housed within the container; an anode in contact with the oxygen-ion-conducting membrane and spaced apart from a metal oxide housed within the container, said anode selected from the group consisting of liquid metal silver, oxygen stable electronic oxides, oxygen stable crucible cermets, and stabilized zirconia composites with oxygen stable electronic oxides.

Environmental Assessment for the Aeromedical Evacuation Formal Training Unit, Wright-Patterson Air Force Base

DTIC Science & Technology

2012-05-01

adverse health effects (HHS 2010). However, propylene glycol requires oxygen for breakdown, which can deplete surface waters of dissolved oxygen ...and the Human Effectiveness Directorate (RH), plus supporting functions. Facility 20840 contains a high-bay area that houses two C-130 training...aircrew training program that develops and maintains a high state of mission readiness for immediate and effective deployments across the range of

Redox-inactive metal ions modulate the reactivity and oxygen release of mononuclear non-haem iron(III)–peroxo complexes

DOE PAGES

Bang, Suhee; Lee, Yong -Min; Hong, Seungwoo; ...

2014-09-14

Redox-inactive metal ions that function as Lewis acids play pivotal roles in modulating the reactivity of oxygen-containing metal complexes and metalloenzymes, such as the oxygen-evolving complex in photosystem II and its small-molecule mimics. Here we report the synthesis and characterization of non-haem iron(III)–peroxo complexes that bind redox-inactive metal ions, (TMC)FeIII–(μ,η 2:η 2-O 2)–M n+ (M n+ = Sr 2+, Ca 2+, Zn 2+, Lu 3+, Y 3+ and Sc 3+; TMC, 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane). We demonstrate that the Ca 2+ and Sr 2+ complexes showed similar electrochemical properties and reactivities in one-electron oxidation or reduction reactions. However, the properties and reactivities ofmore » complexes formed with stronger Lewis acidities were found to be markedly different. In conclusion, complexes that contain Ca 2+ or Sr 2+ ions were oxidized by an electron acceptor to release O 2, whereas the release of O 2 did not occur for complexes that bind stronger Lewis acids. Furthermore, we discuss these results in the light of the functional role of the Ca 2+ ion in the oxidation of water to dioxygen by the oxygen-evolving complex.« less

Redox-inactive metal ions modulate the reactivity and oxygen release of mononuclear non-haem iron(III)–peroxo complexes

PubMed Central

Bang, Suhee; Lee, Yong-Min; Hong, Seungwoo; Cho, Kyung-Bin; Nishida, Yusuke; Seo, Mi Sook; Sarangi, Ritimukta; Fukuzumi, Shunichi; Nam, Wonwoo

2014-01-01

Redox-inactive metal ions that function as Lewis acids play pivotal roles in modulating the reactivity of oxygen-containing metal complexes and metalloenzymes, such as the oxygen-evolving complex in photosystem II and its small-molecule mimics. Here we report the synthesis and characterization of non-haem iron(III)–peroxo complexes that bind redox-inactive metal ions, (TMC)FeIII–(μ,η2:η2-O2)–Mn+ (Mn+ = Sr2+, Ca2+, Zn2+, Lu3+, Y3+ and Sc3+; TMC, 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane). We demonstrate that the Ca2+ and Sr2+ complexes showed similar electrochemical properties and reactivities in one-electron oxidation or reduction reactions. However, the properties and reactivities of complexes formed with stronger Lewis acidities were found to be markedly different. Complexes that contain Ca2+ or Sr2+ ions were oxidized by an electron acceptor to release O2, whereas the release of O2 did not occur for complexes that bind stronger Lewis acids. We discuss these results in the light of the functional role of the Ca2+ ion in the oxidation of water to dioxygen by the oxygen-evolving complex. PMID:25242490

Direct oxygen supply with polydimethylsiloxane (PDMS) membranes induces a spontaneous organization of thick heterogeneous liver tissues from rat fetal liver cells in vitro.

PubMed

Hamon, Morgan; Hanada, Sanshiro; Fujii, Teruo; Sakai, Yasuyuki

2012-01-01

Oxygen is a vital nutrient for growth and maturation of in vitro cells (e.g., adult hepatocytes). We previously demonstrated that direct oxygenation through a polydimethylsiloxane (PDMS) membrane increases the oxygen supply to cell cultures and improves hepatocyte functions. In this study, we removed limits on oxygen supply to fetal rat liver cells through the use of direct oxygenation through a PDMS membrane to investigate in vitro growth and maturation. We chose fetal liver cells because they are considered a feasible source of liver progenitor cells for regenerative medicine therapy due to their highly efficient maturation and proliferation. Cells from 17-day-old pregnant rats were cultured under 5% and 21% oxygen atmospheres. Some cells were first cultured under 5% oxygen, and then switched to a 21% oxygen atmosphere. When oxygen supply was enhanced by a PDMS membrane, the rat fetal liver cells organized into a complex tissue composed of an epithelium of hepatocytes above a mesenchyme-like tissue. The thickness of this supportive tissue was directly correlated to oxygen concentration and was thicker under 5% oxygen. When cultures were switched from 5% to 21% oxygen, lumen-containing structures were formed in the thick mesenchymal-like tissue and the albumin secretion rate increased. In addition, cells adapted their glycolytic activity to the oxygen concentrations. This system promoted the formation of a functional and organized thick tissue suitable for use in regenerative medicine.

Analyzing the dependence of oxygen incorporation current density on overpotential and oxygen partial pressure in mixed conducting oxide electrodes.

PubMed

Guan, Zixuan; Chen, Di; Chueh, William C

2017-08-30

The oxygen incorporation reaction, which involves the transformation of an oxygen gas molecule to two lattice oxygen ions in a mixed ionic and electronic conducting solid, is a ubiquitous and fundamental reaction in solid-state electrochemistry. To understand the reaction pathway and to identify the rate-determining step, near-equilibrium measurements have been employed to quantify the exchange coefficients as a function of oxygen partial pressure and temperature. However, because the exchange coefficient contains contributions from both forward and reverse reaction rate constants and depends on both oxygen partial pressure and oxygen fugacity in the solid, unique and definitive mechanistic assessment has been challenging. In this work, we derive a current density equation as a function of both oxygen partial pressure and overpotential, and consider both near and far from equilibrium limits. Rather than considering specific reaction pathways, we generalize the multi-step oxygen incorporation reaction into the rate-determining step, preceding and following quasi-equilibrium steps, and consider the number of oxygen ions and electrons involved in each. By evaluating the dependence of current density on oxygen partial pressure and overpotential separately, one obtains the reaction orders for oxygen gas molecules and for solid-state species in the electrode. We simulated the oxygen incorporation current density-overpotential curves for praseodymium-doped ceria for various candidate rate-determining steps. This work highlights a promising method for studying the exchange kinetics far away from equilibrium.

Thermal Behaviors and Their Correlations of Mg(BH4)2-Contained Explosives

NASA Astrophysics Data System (ADS)

Yue, Yue; Chen, Liping; Peng, Jinhua

2018-01-01

In order to explore the effect of metal hydride on energetic materials' thermal behaviors and their correlations, we studied the heats of combustion and detonation of RDX, TNT, and Mg(BH4)2-containing explosives both theoretically and experimentally. The results showed that Mg(BH4)2 can significantly improve the energy of explosive. As the mass fraction of Mg(BH4)2 increases, the combustion heat of composite explosives increases gradually, while the combustion efficiency decreases. When its mass fraction is about 30%, the theoretical heats of detonation of RDX/Mg(BH4)2 and TNT/Mg(BH4)2 reach maximum, which are 7418.47 and 7032.46 kJ/kg, respectively. When we compared the errors between calculation and experimental values, we found that L-C method is more accurate in calculating oxygen-enriched and oxygen-balanced explosives, and that minimum free energy method is more suitable for seriously negative oxygen-balanced explosive. For single explosive, there are three kinds of relationships between heat of combustion and detonation according to the oxygen balance. For Mg(BH4)2-containing explosives, the relationship is in accordance with Boltzmann function.

Comparison of functional group selective ion-molecule reactions of trimethyl borate in different ion trap mass spectrometers

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

Habicht, S C; Vinueza, Nelson R; Amundson, Lucas M

2011-02-01

We report here a comparison of the use of diagnostic ion–molecule reactions for the identification of oxygen-containing functional groups in Fourier-transform ion cyclotron resonance (FTICR) and linear quadrupole ion trap (LQIT) mass spectrometers. The ultimate goal of this research is to be able to identify functionalities in previously unknown analytes by using many different types of mass spectrometers. Previous work has focused on the reactions of various boron reagents with protonated oxygen-containing analytes in FTICR mass spectrometers. By using a LQIT modified to allow the introduction of neutral reagents into the helium buffer gas, this methodology has been successfully implementedmore » to this type of an ion trap instrument. The products obtained from the reactions of trimethyl borate (TMB) with various protonated analytes are compared for the two instruments. Finally, the ability to integrate these reactions into LC-MS experiments on the LQIT is demonstrated.« less

Estimation of changes in alveolar-arterial oxygen gradient induced by hypoxia.

PubMed

Hoffstein, V; Duguid, N; Zamel, N; Rebuck, A S

1984-11-01

The alveolar-arterial oxygen tension difference provides a useful clinical indication of ventilation-blood flow mismatching in the lungs. In some clinical situations involving alveolar hypoxia (e.g., patients with chronic obstructive lung disease flying in commercial aircraft or normal humans at high altitudes) it would be useful to know this tension difference to predict the likely arterial PO2 under such potentially stressful conditions. Such estimates would require multiple arterial punctures performed under a variety of trying circumstances, conditions usually far distant from a suitable analytic facility. Consequently, we induced controlled hypoxia in 23 healthy humans and calculated changes in the alveolar-arterial oxygen tension difference during the hypoxic challenge test. We plotted this difference as a function of the alveolar oxygen tension over a range from 35 to 110 mm Hg. In addition to a series of control studies in which multiple arterial blood samples were obtained, we calculated arterial PO2 by converting the arterial oxyhemoglobin saturation (measured with an ear oximeter) into partial pressure of oxygen. During hypoxic procedures in which levels of oxygenation fell on the steep section of the oxyhemoglobin dissociation curve, fixing PCO2 at constant predetermined levels allowed accurate predictions of arterial PO2. We were able to demonstrate that the alveolar-arterial oxygen tension difference narrowed with decreasing alveolar oxygen tension, and that measurement with an ear oximeter provided data that allowed a reasonable estimate of the tension difference during hypoxic conditions.

Removal of hexavalent Cr by coconut coir and derived chars--the effect of surface functionality.

PubMed

Shen, Ying-Shuian; Wang, Shan-Li; Tzou, Yu-Min; Yan, Ya-Yi; Kuan, Wen-Hui

2012-01-01

The Cr(VI) removal by coconut coir (CC) and chars obtained at various pyrolysis temperatures were evaluated. Increasing the pyrolysis temperature resulted in an increased surface area of the chars, while the corresponding content of oxygen-containing functional groups of the chars decreased. The Cr(VI) removal by CC and CC-derived chars was primarily attributed to the reduction of Cr(VI) to Cr(III) by the materials and the extent and rate of the Cr(VI) reduction were determined by the oxygen-containing functional groups in the materials. The contribution of pure Cr(VI) adsorption to the overall Cr(VI) removal became relatively significant for the chars obtained at higher temperatures. Accordingly, to develop a cost-effective method for removing Cr(VI) from water, the original CC is more advantageous than the carbonaceous counterparts because no pyrolysis is required for the application and CC has a higher content of functional groups for reducing Cr(VI) to less toxic Cr(III). Copyright © 2011 Elsevier Ltd. All rights reserved.

A Brief Review on the Use of Functional Near-Infrared Spectroscopy (fNIRS) for Language Imaging Studies in Human Newborns and Adults

ERIC Educational Resources Information Center

Quaresima, Valentina; Bisconti, Silvia; Ferrari, Marco

2012-01-01

Upon stimulation, real time maps of cortical hemodynamic responses can be obtained by non-invasive functional near-infrared spectroscopy (fNIRS) which measures changes in oxygenated and deoxygenated hemoglobin after positioning multiple sources and detectors over the human scalp. The current commercially available transportable fNIRS systems have…

Structural and functional basis of phospholipid oxygenase activity of bacterial lipoxygenase from Pseudomonas aeruginosa.

PubMed

Banthiya, Swathi; Kalms, Jacqueline; Galemou Yoga, Etienne; Ivanov, Igor; Carpena, Xavi; Hamberg, Mats; Kuhn, Hartmut; Scheerer, Patrick

2016-11-01

Pseudomonas aeruginosa expresses a secreted LOX-isoform (PA-LOX, LoxA) capable of oxidizing polyenoic fatty acids to hydroperoxy derivatives. Here we report high-level expression of this enzyme in E. coli and its structural and functional characterization. Recombinant PA-LOX oxygenates polyenoic fatty acids including eicosapentaenoic acid and docosahexaenoic acid to the corresponding (n-6)S-hydroperoxy derivatives. This reaction involves abstraction of the proS-hydrogen from the n-8 bisallylic methylene. PA-LOX lacks major leukotriene synthase activity but converts 5S-HETE and 5S,6R/S-DiHETE to anti-inflammatory and pro-resolving lipoxins. It also exhibits phospholipid oxygenase activity as indicated by the formation of a specific pattern of oxygenation products from different phospholipid subspecies. Multiple mutagenesis studies revealed that PA-LOX does not follow classical concepts explaining the reaction specificity of mammalian LOXs. The crystal structure of PA-LOX was solved with resolutions of up to 1.48Å and its polypeptide chain is folded as single domain. The substrate-binding pocket consists of two fatty acid binding subcavities and lobby. Subcavity-1 contains the catalytic non-heme iron. A phosphatidylethanolamine molecule occupies the substrate-binding pocket and its sn1 fatty acid is located close to the catalytic non-heme iron. His377, His382, His555, Asn559 and the C-terminal Ile685 function as direct iron ligands and a water molecule (hydroxyl) completes the octahedral ligand sphere. Although the biological relevance of PA-LOX is still unknown its functional characteristics (lipoxin synthase activity) implicate this enzyme in a bacterial evasion strategy aimed at downregulating the hosts' immune system. Copyright © 2016 Elsevier B.V. All rights reserved.

Connectivity of glass structure. Oxygen number

NASA Astrophysics Data System (ADS)

Medvedev, E. F.; Min'ko, N. I.

2018-03-01

With reference to mathematics, crystal chemistry and chemical technology of synthesis of glass structures in the solution (sol-gel technology), the paper is devoted to the study of the degree of connectivity of a silicon-oxygen backbone (fSi) and the oxygen number (R) [1]. It reveals logical contradictions and uncertainty of mathematical expressions of parameters, since fSi is not similar to the oxygen number. The connectivity of any structure is a result of various types of bonds: ion-covalent, donor-acceptor, hydrogen bonds, etc. Besides, alongside with SiO2, many glass compositions contain other glass-forming elements due to tetrahedral sites thus formed. The connectivity function of a glassy network with any set of glass-forming elements is roughly ensured by connectivity factor Y [2], which has monovalent elements loosening a glassy network. The paper considers the existence of various structural motives in hydrogen-impermeable glasses containing B2O3, Al2O3, PbO, Na2O, K2O and rare-earth elements. Hence, it also describes gradual nucleation, change of crystal forms, and structure consolidation in the process of substance intake from a matrix solution according to sol-gel technology. The crystal form varied from two-dimensional plates to three-dimensional and dendritical ones [3]. Alternative parameters, such as the oxygen number (O) and the structure connectivity factor (Y), were suggested. Functional dependence of Y=f(O) to forecast the generated structures was obtained for two- and multicomponent glass compositions.

Microwave assisted synthesis of camellia oleifera shell-derived porous carbon with rich oxygen functionalities and superior supercapacitor performance

NASA Astrophysics Data System (ADS)

Liang, Jiyuan; Qu, Tingting; Kun, Xiang; Zhang, Yu; Chen, Shanyong; Cao, Yuan-Cheng; Xie, Mingjiang; Guo, Xuefeng

2018-04-01

Biomass-derived carbon (BDCs) materials are receiving extensive attention as electrode materials for energy storage because of the considerable economic value offering possibility for practical applications, but the electrochemical capacitance of BDCs are usually relatively low resulted from limited electric double layer capacitance. Herein, an oxygen-rich porous carbon (KMAC) was fabricated through a rapid and convenient microwave assisted carbonization and KOH activation of camellia oleifera shell. The obtained KMAC possesses three-dimensional porous architecture, large surface area (1229 m2/g) and rich oxygen functionalities (C/O ratio of 1.66). As the electrode materials for supercapacitor, KMAC exhibits superior supercapacitive performances as compared to the activated carbon (KAC) derived from direct carbonization/KOH activation method in 2.0 M H2SO4 (315 F/g vs. 202 F/g) and 6.0 M KOH (251 F/g vs. 214 F/g) electrolyte due to the rich oxygen-containing functional groups on the surface of porous carbon resulted from the developed microwave-assisted carbonization/activation approach.

A MEMS approach to determine the biochemical oxygen demand (BOD) of wastewaters

NASA Astrophysics Data System (ADS)

Recoules, L.; Migaou, A.; Dollat, X.; Thouand, G.; Gue, A. M.; Boukabache, A.

2017-07-01

A MEMS approach to obtain an efficient tool for the evaluation of the biochemical oxygen demand (BOD) of wastewaters is introduced. Its operating principle is based on the measurement of oxygen concentration in water samples containing organic pollutants and specific bacteria. The microsystem has been designed to perform multiple and parallel measurements in a poly-wells microfluidic device. The monitoring of the bacterial activity is ensured by optical sensors incorporated in each well of the fluidic network. By using an optode sensor, it is hereby demonstrated that this approach is efficient to measure organic pollutants by testing different Luria Bertani buffer dilutions. These results also show that it is possible to reduce the duration of measurements from 5 d (BOD5) of the standard approach to few hours, typically 3 h-5 h.

Sunlight creates oxygenated species in water-soluble fractions of Deepwater Horizon oil.

PubMed

Ray, Phoebe Z; Chen, Huan; Podgorski, David C; McKenna, Amy M; Tarr, Matthew A

2014-09-15

In order to assess the impact of sunlight on oil fate, Macondo well oil from the Deepwater Horizon (DWH) rig was mixed with pure water and irradiated with simulated sunlight. After irradiation, the water-soluble organics (WSO) from the dark and irradiated samples were extracted and characterized by ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Liquid-liquid extraction yielded two fractions from dark and irradiated water/oil mixtures: acidic WSOs (negative-ion electrospray (ESI)), and base/neutral WSOs (positive-ion ESI) coupled to FT-ICR MS to catalog molecular-level transformations that occur to Macondo-derived WSOs after solar irradiation. Such direct measure of oil phototransformation has not been previously reported. The most abundant heteroatom class detected in the irradiated WSO acid fractions correspond to molecules that contain five oxygens (O5), while the most abundant acids in the dark samples contain two oxygen atoms per molecule (O2). Higher-order oxygen classes (O5-O9) were abundant in the irradiated samples, but <1.5% relative abundance in the dark sample. The increased abundance of higher-order oxygen classes in the irradiated samples relative to the dark samples indicates that photooxidized components of the Macondo crude oil become water-soluble after irradiation. The base/neutral fraction showed decreased abundance of pyridinic nitrogen (N1) concurrent with an increased abundance of N1Ox classes after irradiation. The predominance of higher-order oxygen classes indicates that multiple photochemical pathways exist that result in oxidation of petroleum compounds. Copyright © 2014 Elsevier B.V. All rights reserved.

Metal-air cells comprising collapsible foam members and means for minimizing internal pressure buildup

NASA Technical Reports Server (NTRS)

Putt, Ronald A. (Inventor); Woodruff, Glenn (Inventor)

1994-01-01

This invention provides a prismatic zinc-air cell including, in general, a prismatic container having therein an air cathode, a separator and a zinc anode. The container has one or more oxygen access openings, and the air cathode is disposed in the container in gaseous communication with the oxygen access openings so as to allow access of oxygen to the cathode. The separator has a first side in electrolytic communication with the air cathode and a second side in electrolytic communication with the zinc anode. The separator isolates the cathode and the zinc anode from direct electrical contact and allows passage of electrolyte therebetween. An expansion chamber adjacent to the zinc anode is provided which accommodates expansion of the zinc anode during discharge of the cell. A suitable collapsible foam member generally occupies the expansion space, providing sufficient resistance tending to oppose movement of the zinc anode away from the separator while collapsing upon expansion of the zinc anode during discharge of the cell. One or more vent openings disposed in the container are in gaseous communication with the expansion space, functioning to satisfactorily minimize the pressure buildup within the container by venting gasses expelled as the foam collapses during cell discharge.

Ferritins: dynamic management of biological iron and oxygen chemistry.

PubMed

Liu, Xiaofeng; Theil, Elizabeth C

2005-03-01

Ferritins are spherical, cage-like proteins with nanocavities formed by multiple polypeptide subunits (four-helix bundles) that manage iron/oxygen chemistry. Catalytic coupling yields diferric oxo/hydroxo complexes at ferroxidase sites in maxi-ferritin subunits (24 subunits, 480 kDa; plants, animals, microorganisms). Oxidation occurs at the cavity surface of mini-ferritins/Dps proteins (12 subunits, 240 kDa; bacteria). Oxidation products are concentrated as minerals in the nanocavity for iron-protein cofactor synthesis (maxi-ferritins) or DNA protection (mini-ferritins). The protein cage and nanocavity characterize all ferritins, although amino acid sequences diverge, especially in bacteria. Catalytic oxidation/di-iron coupling in the protein cage (maxi-ferritins, 480 kDa; plants, bacteria and animal cell-specific isoforms) or on the cavity surface (mini-ferritins/Dps proteins, 280 kDa; bacteria) initiates mineralization. Gated pores (eight or four), symmetrically arranged, control iron flow. The multiple ferritin functions combine pore, channel, and catalytic functions in compact protein structures required for life and disease response.

Simple synthetic route to manganese-containing nanowires with the spinel crystal structure

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

Yu, Lei; Zhang, Yan; Hudak, Bethany M.

This report describes a new route to synthesize single-crystalline manganese-containing spinel nanowires (NWs) by a two-step hydrothermal and solid-state synthesis. Interestingly, a nanowire or nanorod morphology is maintained during conversion from MnO{sub 2}/MnOOH to CuMn{sub 2}O{sub 4}/Mg{sub 2}MnO{sub 4}, despite the massive structural rearrangement this must involve. Linear sweep voltammetry (LSV) curves of the products give preliminary demonstration that CuMn{sub 2}O{sub 4} NWs are catalytically active towards the oxygen evolution reaction (OER) in alkaline solution, exhibiting five times the magnitude of current density found with pure carbon black. - Highlights: • Synthesis of single-crystalline manganese-containing spinel nanowires. • Binary oxidemore » nanowire converted to ternary oxide wire through solid state reaction. • Approach to structure conversion with shape retention could be generally applicable. • Copper and Manganese display multiple oxidation states with potential for catalysis. • CuMn{sub 2}O{sub 4} nanowires show promise as catalysts for the oxygen evolution reaction.« less

The NASA Ames PAH IR Spectroscopic Database: Computational Version 3.00 with Updated Content and the Introduction of Multiple Scaling Factors

NASA Astrophysics Data System (ADS)

Bauschlicher, Charles W., Jr.; Ricca, A.; Boersma, C.; Allamandola, L. J.

2018-02-01

Version 3.00 of the library of computed spectra in the NASA Ames PAH IR Spectroscopic Database (PAHdb) is described. Version 3.00 introduces the use of multiple scale factors, instead of the single scaling factor used previously, to align the theoretical harmonic frequencies with the experimental fundamentals. The use of multiple scale factors permits the use of a variety of basis sets; this allows new PAH species to be included in the database, such as those containing oxygen, and yields an improved treatment of strained species and those containing nitrogen. In addition, the computed spectra of 2439 new PAH species have been added. The impact of these changes on the analysis of an astronomical spectrum through database-fitting is considered and compared with a fit using Version 2.00 of the library of computed spectra. Finally, astronomical constraints are defined for the PAH spectral libraries in PAHdb.

NIR spectroscopic investigation of m. vastus lateralis in patients with mitochondrial myopathies as detected by respirometric investigation of mitochondrial function in skinned fibers

NASA Astrophysics Data System (ADS)

Gellerich, Frank N.; Mueller, Tobias; Nioka, Shoko; Hertel, Katrin; Schulte-Mattler, Wilhelm J.; Zierz, Stephan; Chance, Britton

1998-01-01

Noninvasive measurement of changes in oxygenation of human skeletal muscle can be done with a dual-wavelength near infrared (NIR) spectrophotometer. This allows a noninvasive investigation of muscle mitochondria. An exercise protocol was developed to study the load dependent changes in oxygenation of m. vastus lateralis of myopathic patients. On a bicycle ergometer exercise was done periodically. One period consisted of 1.5 min exercise followed by 3 min rest. Work load in the first period was 20 W, and was increased by 10 W for each subsequent period until maximal work load was reached. In 12 healthy volunteers we observed oxygenation of muscle during periods of low work load (warm-up effect). During periods of high work load the muscle deoxygenated. The work load at transition from oxygenation to deoxygenation (deoxygenation threshold) in controls was 75 W. In 3 patients with myopathies, in addition to NIR- spectroscopy, function of mitochondria of specimen of m. vastus lateralis was investigated biochemically. Muscle fibers were skinned with saponin and investigated with high resolution respirometry and multiple substrate-inhibitor- titration. Mitochondrial function was impaired in patients who had abnormal findings in NIR spectroscopy.

NIR spectroscopic investigation of m. vastus lateralis in patients with mitochondrial myopathies as detected by respirometric investigation of mitochondrial function in skinned fibers

NASA Astrophysics Data System (ADS)

Gellerich, Frank N.; Mueller, Tobias; Nioka, Shoko; Hertel, Katrin; Schulte-Mattler, Wilhelm J.; Zierz, Stephan; Chance, Britton

1997-12-01

Noninvasive measurement of changes in oxygenation of human skeletal muscle can be done with a dual-wavelength near infrared (NIR) spectrophotometer. This allows a noninvasive investigation of muscle mitochondria. An exercise protocol was developed to study the load dependent changes in oxygenation of m. vastus lateralis of myopathic patients. On a bicycle ergometer exercise was done periodically. One period consisted of 1.5 min exercise followed by 3 min rest. Work load in the first period was 20 W, and was increased by 10 W for each subsequent period until maximal work load was reached. In 12 healthy volunteers we observed oxygenation of muscle during periods of low work load (warm-up effect). During periods of high work load the muscle deoxygenated. The work load at transition from oxygenation to deoxygenation (deoxygenation threshold) in controls was 75 W. In 3 patients with myopathies, in addition to NIR- spectroscopy, function of mitochondria of specimen of m. vastus lateralis was investigated biochemically. Muscle fibers were skinned with saponin and investigated with high resolution respirometry and multiple substrate-inhibitor- titration. Mitochondrial function was impaired in patients who had abnormal findings in NIR spectroscopy.

Interplay between Oxygen and Fe–S Cluster Biogenesis: Insights from the Suf Pathway

PubMed Central

2015-01-01

Iron–sulfur (Fe–S) cluster metalloproteins conduct essential functions in nearly all contemporary forms of life. The nearly ubiquitous presence of Fe–S clusters and the fundamental requirement for Fe–S clusters in both aerobic and anaerobic Archaea, Bacteria, and Eukarya suggest that these clusters were likely integrated into central metabolic pathways early in the evolution of life prior to the widespread oxidation of Earth’s atmosphere. Intriguingly, Fe–S cluster-dependent metabolism is sensitive to disruption by oxygen because of the decreased bioavailability of ferric iron as well as direct oxidation of sulfur trafficking intermediates and Fe–S clusters by reactive oxygen species. This fact, coupled with the ubiquity of Fe–S clusters in aerobic organisms, suggests that organisms evolved with mechanisms that facilitate the biogenesis and use of these essential cofactors in the presence of oxygen, which gradually began to accumulate around 2.5 billion years ago as oxygenic photosynthesis proliferated and reduced minerals that buffered against oxidation were depleted. This review highlights the most ancient of the Fe–S cluster biogenesis pathways, the Suf system, which likely was present in early anaerobic forms of life. Herein, we use the evolution of the Suf pathway to assess the relationships between the biochemical functions and physiological roles of Suf proteins, with an emphasis on the selective pressure of oxygen toxicity. Our analysis suggests that diversification into oxygen-containing environments disrupted iron and sulfur metabolism and was a main driving force in the acquisition of accessory Suf proteins (such as SufD, SufE, and SufS) by the core SufB–SufC scaffold complex. This analysis provides a new framework for the study of Fe–S cluster biogenesis pathways and Fe–S cluster-containing metalloenzymes and their complicated patterns of divergence in response to oxygen. PMID:25153801

Differential Item Functioning Detection Using the Multiple Indicators, Multiple Causes Method with a Pure Short Anchor

ERIC Educational Resources Information Center

Shih, Ching-Lin; Wang, Wen-Chung

2009-01-01

The multiple indicators, multiple causes (MIMIC) method with a pure short anchor was proposed to detect differential item functioning (DIF). A simulation study showed that the MIMIC method with an anchor of 1, 2, 4, or 10 DIF-free items yielded a well-controlled Type I error rate even when such tests contained as many as 40% DIF items. In general,…

Cardiorespiratory demand of acute voluntary cycling with functional electrical stimulation in individuals with multiple sclerosis with severe mobility impairment.

PubMed

Edwards, Thomas; Motl, Robert W; Pilutti, Lara A

2018-01-01

Exercise training is one strategy for improving cardiorespiratory fitness (CRF) in multiple sclerosis (MS); however, few modalities are accessible for those with severe mobility impairment. Functional electrical stimulation (FES) cycling is an adapted exercise modality with the potential for improving CRF in people with severe MS. The objective of this study was to characterize the cardiorespiratory response of acute voluntary cycling with FES in people with MS with severe mobility impairment, and to compare this response to passive leg cycling. Eleven participants with MS that required assistance for ambulation completed a single bout of voluntary cycling with FES or passive leg cycling. Oxygen consumption, heart rate (HR), work rate (WR), and ratings of perceived exertion (RPE) were recorded throughout the session. For the FES group, mean exercising oxygen consumption was 8.7 ± 1.8 mL/(kg·min) -1 , or 63.5% of peak oxygen consumption. Mean HR was 102 ± 9.7 bpm, approximately 76.4% of peak HR. Mean WR was 27.0 ± 9.2 W, or 57.3% of peak WR, and median RPE was 13.5 (interquartile range = 5.5). Active cycling with FES was significantly (p < 0.05) more intense than passive leg cycling based on oxygen consumption, HR, WR, and RPE during exercise. In conclusion, voluntary cycling with FES elicited an acute response that corresponded with moderate-to vigorous-intensity activity, suggesting that active cycling with FES can elicit a sufficient stimulus for improving CRF.

Ventilation heterogeneity measured by multiple breath inert gas testing is not affected by inspired oxygen concentration in healthy humans

PubMed Central

Elliott, Ann R.; Prisk, G. Kim; Darquenne, Chantal

2017-01-01

Multiple breath washout (MBW) and oxygen-enhanced MRI techniques use acute exposure to 100% oxygen to measure ventilation heterogeneity. Implicit is the assumption that breathing 100% oxygen does not induce changes in ventilation heterogeneity; however, this is untested. We hypothesized that ventilation heterogeneity decreases with increasing inspired oxygen concentration in healthy subjects. We performed MBW in 8 healthy subjects (4 women, 4 men; age = 43 ± 15 yr) with normal pulmonary function (FEV1 = 98 ± 6% predicted) using 10% argon as a tracer gas and oxygen concentrations of 12.5%, 21%, or 90%. MBW was performed in accordance with ERS-ATS guidelines. Subjects initially inspired air followed by a wash-in of test gas. Tests were performed in balanced order in triplicate. Gas concentrations were measured at the mouth, and argon signals rescaled to mimic a N2 washout, and analyzed to determine the distribution of specific ventilation (SV). Heterogeneity was characterized by the width of a log-Gaussian fit of the SV distribution and from Sacin and Scond indexes derived from the phase III slope. There were no significant differences in the ventilation heterogeneity due to altered inspired oxygen: histogram width (hypoxia 0.57 ± 0.11, normoxia 0.60 ± 0.08, hyperoxia 0.59 ± 0.09, P = 0.51), Scond (hypoxia 0.014 ± 0.011, normoxia 0.012 ± 0.015, hyperoxia 0.010 ± 0.011, P = 0.34), or Sacin (hypoxia 0.11 ± 0.04, normoxia 0.10 ± 0.03, hyperoxia 0.12 ± 0.03, P = 0.23). Functional residual capacity was increased in hypoxia (P = 0.04) and dead space increased in hyperoxia (P = 0.0001) compared with the other conditions. The acute use of 100% oxygen in MBW or MRI is unlikely to affect ventilation heterogeneity. NEW & NOTEWORTHY Hyperoxia is used to measure the distribution of ventilation in imaging and MBW but may alter the underlying ventilation distribution. We used MBW to evaluate the effect of inspired oxygen concentration on the ventilation distribution using 10% argon as a tracer. Short-duration exposure to hypoxia (12.5% oxygen) and hyperoxia (90% oxygen) during MBW had no significant effect on ventilation heterogeneity, suggesting that hyperoxia can be used to assess the ventilation distribution. PMID:28280107

Ventilation heterogeneity measured by multiple breath inert gas testing is not affected by inspired oxygen concentration in healthy humans.

PubMed

Hopkins, Susan R; Elliott, Ann R; Prisk, G Kim; Darquenne, Chantal

2017-06-01

Multiple breath washout (MBW) and oxygen-enhanced MRI techniques use acute exposure to 100% oxygen to measure ventilation heterogeneity. Implicit is the assumption that breathing 100% oxygen does not induce changes in ventilation heterogeneity; however, this is untested. We hypothesized that ventilation heterogeneity decreases with increasing inspired oxygen concentration in healthy subjects. We performed MBW in 8 healthy subjects (4 women, 4 men; age = 43 ± 15 yr) with normal pulmonary function (FEV 1 = 98 ± 6% predicted) using 10% argon as a tracer gas and oxygen concentrations of 12.5%, 21%, or 90%. MBW was performed in accordance with ERS-ATS guidelines. Subjects initially inspired air followed by a wash-in of test gas. Tests were performed in balanced order in triplicate. Gas concentrations were measured at the mouth, and argon signals rescaled to mimic a N 2 washout, and analyzed to determine the distribution of specific ventilation (SV). Heterogeneity was characterized by the width of a log-Gaussian fit of the SV distribution and from S acin and S cond indexes derived from the phase III slope. There were no significant differences in the ventilation heterogeneity due to altered inspired oxygen: histogram width (hypoxia 0.57 ± 0.11, normoxia 0.60 ± 0.08, hyperoxia 0.59 ± 0.09, P = 0.51), S cond (hypoxia 0.014 ± 0.011, normoxia 0.012 ± 0.015, hyperoxia 0.010 ± 0.011, P = 0.34), or S acin (hypoxia 0.11 ± 0.04, normoxia 0.10 ± 0.03, hyperoxia 0.12 ± 0.03, P = 0.23). Functional residual capacity was increased in hypoxia ( P = 0.04) and dead space increased in hyperoxia ( P = 0.0001) compared with the other conditions. The acute use of 100% oxygen in MBW or MRI is unlikely to affect ventilation heterogeneity. NEW & NOTEWORTHY Hyperoxia is used to measure the distribution of ventilation in imaging and MBW but may alter the underlying ventilation distribution. We used MBW to evaluate the effect of inspired oxygen concentration on the ventilation distribution using 10% argon as a tracer. Short-duration exposure to hypoxia (12.5% oxygen) and hyperoxia (90% oxygen) during MBW had no significant effect on ventilation heterogeneity, suggesting that hyperoxia can be used to assess the ventilation distribution. Copyright © 2017 the American Physiological Society.

Plasma enhancement of in vitro attachment of rat bone-marrow-derived stem cells on cross-linked gelatin films.

PubMed

Prasertsung, I; Kanokpanont, S; Mongkolnavin, R; Wong, C S; Panpranot, J; Damrongsakkul, S

2012-01-01

In this work, nitrogen, oxygen and air glow discharges powered by 50 Hz AC power supply are used for the treatment of type-A gelatin film cross-linked by a dehydrothermal (DHT) process. The properties of cross-linked gelatin were characterized by contact angle measurement, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) analysis. The results showed that the water contact angle of gelatin films decrease with increasing plasma treatment time. The treatment of nitrogen, oxygen and air plasma up to 30 s had no effects on the surface roughness of the gelatin film as revealed by AFM results. The XPS analysis showed that the N-containing functional groups generated by nitrogen and air plasma, and O-containing functional groups generated by oxygen and air plasmas were incorporated onto the film surface, the functional groups were found to increase with increasing treatment time. An in vitro test using rat bone-marrow-mesenchym-derived stem cells (MSCs) revealed that the number of cells attached on plasma-treated gelatin films was significantly increased compared to untreated samples. The best enhancement of cell attachment was noticed when the film was treated with nitrogen plasma for 15-30 s, oxygen plasma for 3 s, and air plasma for 9 s. In addition, among the three types of plasmas used, nitrogen plasma treatment gave the best MSCs attachment on the gelatin surface. The results suggest that a type-A gelatin film with water contact angle of 27-28° and an O/N ratio of 1.4 is most suitable for MSCs attachment.

Development of Low Cost Gas Atomization of Precursor Powders for Simplified ODS Alloy Production

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

Anderson, Iver

2014-08-05

A novel gas atomization reaction synthesis (GARS) method was developed in this project to enable production (at our partner’s facility) a precursor Ni-Cr-Y-Ti powder with a surface oxide and an internal rare earth (RE) containing intermetallic compound (IMC) phase. Consolidation and heat-treatment experiments were performed at Ames Lab to promote the exchange of oxygen from the surface oxide to the RE intermetallic to form nano-metric oxide dispersoids. Alloy selection was aided by an internal oxidation and serial grinding experiments at Ames Lab and found that Hf-containing alloys may form more stable dispersoids than Ti-containing alloy, i.e., the Hf-containing system exhibitedmore » five different oxide phases and two different intermetallics compared to the two oxide phases and one intermetallic in the Ti-containing alloys. Since the simpler Ti-containing system was less complex to characterize, and make observations on the effects of processing parameters, the Ti-containing system was selected by Ames Lab for experimental atomization trials at our partner. An internal oxidation model was developed at Ames Lab and used to predict the heat treatment times necessary for dispersoid formation as a function of powder size and temperature. A new high-pressure gas atomization (HPGA) nozzle was developed at Ames Lab with the aim of promoting fine powder production at scales similar to that of the high gas-flow and melt-flow of industrial atomizers. The atomization nozzle was characterized using schlieren imaging and aspiration pressure testing at Ames Lab to determine the optimum melt delivery tip geometry and atomization pressure to promote enhanced secondary atomization mechanisms. Six atomization trials were performed at our partner to investigate the effects of: gas atomization pressure and reactive gas concentration on the particle size distribution (PSD) and the oxygen content of the resulting powder. Also, the effect on the rapidly solidified microstructure (as a function of powder size) was investigated at Ames Lab as a function of reactive gas composition and bulk alloy composition. The results indicated that the pulsatile gas atomization mechanism and a significantly enhanced yield of fine powders reported in the literature for this type of process were not observed. Also it was determined that reactive gas may marginally improve the fine powder yield but further experiments are required. The oxygen content in the gas also did not have any detrimental effect on the microstructure (i.e. did not significantly reduce undercooling). On the contrary, the oxygen addition to the atomization gas may have mitigated some potent catalytic nucleation sites, but not enough to significantly alter the microstructure vs. particle size relationship. Overall the downstream injection of oxygen was not found to significantly affect either the particle size distribution or undercooling (as inferred from microstructure and XRD observations) but injection further upstream, including in the gas atomization nozzle, remains to be investigated in later work.« less

Positive selection in octopus haemocyanin indicates functional links to temperature adaptation.

PubMed

Oellermann, Michael; Strugnell, Jan M; Lieb, Bernhard; Mark, Felix C

2015-07-05

Octopods have successfully colonised the world's oceans from the tropics to the poles. Yet, successful persistence in these habitats has required adaptations of their advanced physiological apparatus to compensate impaired oxygen supply. Their oxygen transporter haemocyanin plays a major role in cold tolerance and accordingly has undergone functional modifications to sustain oxygen release at sub-zero temperatures. However, it remains unknown how molecular properties evolved to explain the observed functional adaptations. We thus aimed to assess whether natural selection affected molecular and structural properties of haemocyanin that explains temperature adaptation in octopods. Analysis of 239 partial sequences of the haemocyanin functional units (FU) f and g of 28 octopod species of polar, temperate, subtropical and tropical origin revealed natural selection was acting primarily on charge properties of surface residues. Polar octopods contained haemocyanins with higher net surface charge due to decreased glutamic acid content and higher numbers of basic amino acids. Within the analysed partial sequences, positive selection was present at site 2545, positioned between the active copper binding centre and the FU g surface. At this site, methionine was the dominant amino acid in polar octopods and leucine was dominant in tropical octopods. Sites directly involved in oxygen binding or quaternary interactions were highly conserved within the analysed sequence. This study has provided the first insight into molecular and structural mechanisms that have enabled octopods to sustain oxygen supply from polar to tropical conditions. Our findings imply modulation of oxygen binding via charge-charge interaction at the protein surface, which stabilize quaternary interactions among functional units to reduce detrimental effects of high pH on venous oxygen release. Of the observed partial haemocyanin sequence, residue 2545 formed a close link between the FU g surface and the active centre, suggesting a role as allosteric binding site. The prevalence of methionine at this site in polar octopods, implies regulation of oxygen affinity via increased sensitivity to allosteric metal binding. High sequence conservation of sites directly involved in oxygen binding indicates that functional modifications of octopod haemocyanin rather occur via more subtle mechanisms, as observed in this study.

Sleep and Cognitive Function in Multiple Sclerosis.

PubMed

Braley, Tiffany J; Kratz, Anna L; Kaplish, Neeraj; Chervin, Ronald D

2016-08-01

To examine associations between cognitive performance and polysomnographic measures of obstructive sleep apnea in patients with multiple sclerosis (MS). Participants underwent a comprehensive MS-specific cognitive testing battery (the Minimal Assessment of Cognitive Function in MS, or MACFIMS) and in-laboratory overnight PSG. In adjusted linear regression models, the oxygen desaturation index (ODI) and minimum oxygen saturation (MinO2) were significantly associated with performance on multiple MACFIMS measures, including the Paced Auditory Serial Addition Test (PASAT; 2-sec and 3-sec versions), which assesses working memory, processing speed, and attention, and on the Brief Visuospatial Memory Test-Revised, a test of delayed visual memory. The respiratory disturbance index (RDI) was also significantly associated with PASAT-3 scores as well as the California Verbal Learning Test-II (CVLT-II) Discriminability Index, a test of verbal memory and response inhibition. Among these associations, apnea severity measures accounted for between 12% and 23% of the variance in cognitive test performance. Polysomnographic measures of sleep fragmentation (as reflected by the total arousal index) and total sleep time also showed significant associations with a component of the CVLT-II that assesses response inhibition, explaining 18% and 27% of the variance in performance. Among patients with MS, obstructive sleep apnea and sleep disturbance are significantly associated with diminished visual memory, verbal memory, executive function (as reflected by response inhibition), attention, processing speed, and working memory. If sleep disorders degrade these cognitive functions, effective treatment could offer new opportunities to improve cognitive functioning in patients with MS. A commentary on this article appears in this issue on page 1489. © 2016 Associated Professional Sleep Societies, LLC.

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

Sokhansanj, Shahabaddine; Kuang, Xingya; Shankar, T.S.

Few papers have been published in the open literature on the emissions from biomass fuels, including wood pellets, during the storage and transportation and their potential health impacts. The purpose of this study is to provide data on the concentrations, emission factors, and emission rate factors of CO2, CO, and CH4 from wood pellets stored with different headspace to container volume ratios with different initial oxygen levels, in order to develop methods to reduce the toxic off-gas emissions and accumulation in storage spaces. Metal containers (45 l, 305 mm diameter by 610 mm long) were used to study the effectmore » of headspace and oxygen levels on the off-gas emissions from wood pellets. Concentrations of CO2, CO, and CH4 in the headspace were measured using a gas chromatograph as a function of storage time. The results showed that the ratio of the headspace ratios and initial oxygen levels in the storage space significantly affected the off-gas emissions from wood pellets stored in a sealed container. Higher peak emission factors and higher emission rates are associated with higher headspace ratios. Lower emissions of CO2 and CO were generated at room temperature under lower oxygen levels, whereas CH4 emission is insensitive to the oxygen level. Replacing oxygen with inert gases in the storage space is thus a potentially effective method to reduce the biomass degradation and toxic off-gas emissions. The proper ventilation of the storage space can also be used to maintain a high oxygen level and low concentrations of toxic off-gassing compounds in the storage space, which is especially useful during the loading and unloading operations to control the hazards associated with the storage and transportation of wood pellets.« less

A wheat WRKY transcription factor TaWRKY10 confers tolerance to multiple abiotic stresses in transgenic tobacco.

PubMed

Wang, Chen; Deng, Pengyi; Chen, Liulin; Wang, Xiatian; Ma, Hui; Hu, Wei; Yao, Ningcong; Feng, Ying; Chai, Ruihong; Yang, Guangxiao; He, Guangyuan

2013-01-01

WRKY transcription factors are reported to be involved in defense regulation, stress response and plant growth and development. However, the precise role of WRKY transcription factors in abiotic stress tolerance is not completely understood, especially in crops. In this study, we identified and cloned 10 WRKY genes from genome of wheat (Triticum aestivum L.). TaWRKY10, a gene induced by multiple stresses, was selected for further investigation. TaWRKY10 was upregulated by treatment with polyethylene glycol, NaCl, cold and H2O2. Result of Southern blot indicates that the wheat genome contains three copies of TaWRKY10. The TaWRKY10 protein is localized in the nucleus and functions as a transcriptional activator. Overexpression of TaWRKY10 in tobacco (Nicotiana tabacum L.) resulted in enhanced drought and salt stress tolerance, mainly demonstrated by the transgenic plants exhibiting of increased germination rate, root length, survival rate, and relative water content under these stress conditions. Further investigation showed that transgenic plants also retained higher proline and soluble sugar contents, and lower reactive oxygen species and malonaldehyde contents. Moreover, overexpression of the TaWRKY10 regulated the expression of a series of stress related genes. Taken together, our results indicate that TaWRKY10 functions as a positive factor under drought and salt stresses by regulating the osmotic balance, ROS scavenging and transcription of stress related genes.

Multipurpose Vacuum Induction Processing System

NASA Astrophysics Data System (ADS)

Govindaraju, M.; Kulkarni, Deepak; Balasubramanian, K.

2012-11-01

Multipurpose vacuum processing systems are cost effective; occupy less space, multiple functional under one roof and user friendly. A multipurpose vacuum induction system was designed, fabricated and installed in a record time of 6 months time at NFTDC Hyderabad. It was designed to function as a) vacuum induction melting/refining of oxygen free electronic copper/pure metals, b) vacuum induction melting furnace for ferrous materials c) vacuum induction melting for non ferrous materials d) large vacuum heat treatment chamber by resistance heating (by detachable coil and hot zone) e) bottom discharge vacuum induction melting system for non ferrous materials f) Induction heat treatment system and g) directional solidification /investment casting. It contains provision for future capacity addition. The attachments require to manufacture multiple shaped castings and continuous rod casting can be added whenever need arises. Present capacity is decided on the requirement for 10years of development path; presently it has 1.2 ton liquid copper handling capacity. It is equipped with provision for capacity addition up to 2 ton liquid copper handling capacity in future. Provision is made to carry out the capacity addition in easy steps quickly. For easy operational maintenance and troubleshooting, design was made in easily detachable sections. High vacuum system is also is detachable, independent and easily movable which is first of its kind in the country. Detailed design parameters, advantages and development history are presented in this paper.

Tailoring properties of reduced graphene oxide by oxygen plasma treatment

NASA Astrophysics Data System (ADS)

Kondratowicz, Izabela; Nadolska, Małgorzata; Şahin, Samet; Łapiński, Marcin; Prześniak-Welenc, Marta; Sawczak, Mirosław; Yu, Eileen H.; Sadowski, Wojciech; Żelechowska, Kamila

2018-05-01

We report an easily controllable, eco-friendly method for tailoring the properties of reduced graphene oxide (rGO) by means of oxygen plasma. The effect of oxygen plasma treatment time (1, 5 and 10 min) on the surface properties of rGO was evaluated. Physicochemical characterization using microscopic, spectroscopic and thermal techniques was performed. The results revealed that different oxygen-containing groups (e.g. carboxyl, hydroxyl) were introduced on the rGO surface enhancing its wettability. Furthermore, upon longer treatment time, other functionalities were created (e.g. quinones, lactones). Moreover, external surface of rGO was partially etched resulting in an increase of the material surface area and porosity. Finally, the oxygen plasma-treated rGO electrodes with bilirubin oxidase were tested for oxygen reduction reaction. The study showed that rGO treated for 10 min exhibited twofold higher current density than untreated rGO. The oxygen plasma treatment may improve the enzyme adsorption on rGO electrodes by introduction of oxygen moieties and increasing the porosity.

In-situ micro-FTIR Study of Thermal Changes of Organics in Tagish Lake Meteorite: Behavior of Aliphatic Oxygenated Functions and Effects of Minerals

NASA Technical Reports Server (NTRS)

Kebukawa, Yoko; Nakashima, Satoru; Nakamura-Messenger, Keiko; Zolensky, Michael E.

2007-01-01

Systematic in-situ FTIR heating experiments of Tagish Lake meteorite grains have been performed in order to study thermal stability of chondritic organics. Some aliphatic model organic substances have also been used to elucidate effects of hydrous phyllosilicate minerals on the thermal stability of organics. The experimental results indicated that organic matter in the Tagish Lake meteorite might contain oxygenated aliphatic hydrocarbons which are thermally stable carbonyls such as ester and/or C=O in ring compounds. The presence of hydrous phyllosilicate minerals has a pronounced effect on the increase of the thermal stability of aliphatic and oxygenated functions. These oxygenated aliphatic organics in Tagish Lake can be formed during the aqueous alteration in the parent body and the formation temperature condition might be less than 200 C, based especially on the thermal stability of C-O components. The hydrous phyllosilicates might provide sites for organic globule formation and protected some organic decomposition

Method for converting hydrocarbon fuel into hydrogen gas and carbon dioxide

DOEpatents

Clawson, Lawrence G.; Mitchell, William L.; Bentley, Jeffrey M.; Thijssen, Johannes H. J.

2000-01-01

A method for converting hydrocarbon fuel into hydrogen gas and carbon dioxide within a reformer 10 is disclosed. According to the method, a stream including an oxygen-containing gas is directed adjacent to a first vessel 18 and the oxygen-containing gas is heated. A stream including unburned fuel is introduced into the oxygen-containing gas stream to form a mixture including oxygen-containing gas and fuel. The mixture of oxygen-containing gas and unburned fuel is directed tangentially into a partial oxidation reaction zone 24 within the first vessel 18. The mixture of oxygen-containing gas and fuel is further directed through the partial oxidation reaction zone 24 to produce a heated reformate stream including hydrogen gas and carbon monoxide. Steam may also be mixed with the oxygen-containing gas and fuel, and the reformate stream from the partial oxidation reaction zone 24 directed into a steam reforming zone 26. High- and low-temperature shift reaction zones 64,76 may be employed for further fuel processing.

Study on Oxygen Supply Standard for Physical Health of Construction Personnel of High-Altitude Tunnels.

PubMed

Guo, Chun; Xu, Jianfeng; Wang, Mingnian; Yan, Tao; Yang, Lu; Sun, Zhitao

2015-12-22

The low atmospheric pressure and low oxygen content in high-altitude environment have great impacts on the functions of human body. Especially for the personnel engaged in complicated physical labor such as tunnel construction, high altitude can cause a series of adverse physiological reactions, which may result in multiple high-altitude diseases and even death in severe cases. Artificial oxygen supply is required to ensure health and safety of construction personnel in hypoxic environments. However, there are no provisions for oxygen supply standard for tunnel construction personnel in high-altitude areas in current tunnel construction specifications. As a result, this paper has theoretically studied the impacts of high-altitude environment on human bodies, analyzed the relationship between labor intensity and oxygen consumption in high-altitude areas and determined the critical oxygen-supply altitude values for tunnel construction based on two different standard evaluation systems, i.e., variation of air density and equivalent PIO₂. In addition, it has finally determined the oxygen supply standard for construction personnel in high-altitude areas based on the relationship between construction labor intensity and oxygen consumption.

Evolution of Metallicity in Vanadium Dioxide by Creation of Oxygen Vacancies

NASA Astrophysics Data System (ADS)

Zhang, Zhen; Zuo, Fan; Wan, Chenghao; Dutta, Aveek; Kim, Jongbum; Rensberg, Jura; Nawrodt, Ronny; Park, Helen Hejin; Larrabee, Thomas J.; Guan, Xiaofei; Zhou, You; Prokes, S. M.; Ronning, Carsten; Shalaev, Vladimir M.; Boltasseva, Alexandra; Kats, Mikhail A.; Ramanathan, Shriram

2017-03-01

Tuning of the electronic state of correlated materials is key to their eventual use in advanced electronics and photonics. The prototypical correlated oxide (VO2 ) is insulating at room temperature and transforms to a metallic state when heated to 67 °C (340 K). We report the emergence of a metallic state that is preserved down to 1.8 K by annealing thin films of VO2 at an ultralow oxygen partial pressure (PO2˜10-24 atm ). The films can be reverted back to their original state by annealing in oxygen, and this process can be iterated multiple times. The metallic phase created by oxygen deficiency has a tetragonal rutile structure and contains a large number of oxygen vacancies far beyond the solubility at equilibrium (greater than approximately 50 times). The oxygen starvation reduces the oxidation state of vanadium from V4 + to V3 + and leads to the metallization. The extent of resistance reduction (concurrent with tuning of optical properties) can be controlled by the time-temperature envelope of the annealing conditions since the process is diffusionally driven. This experimental platform, which can extensively tune oxygen vacancies in correlated oxides, provides an approach to study emergent phases and defect-mediated adaptive electronic and structural phase boundary crossovers.

Defect-related electroluminescence from metal-oxide-semiconductor devices with ZrO2 films on silicon

NASA Astrophysics Data System (ADS)

Lv, Chunyan; Zhu, Chen; Wang, Canxing; Li, Dongsheng; Ma, Xiangyang; Yang, Deren

2016-11-01

Defect-related electroluminescence (EL) from ZrO2 films annealed under different atmosphere has been realized by means of electrical pumping scheme of metal-oxide-semiconductor (MOS) devices. At the same injection current, the acquired EL from the MOS device with the vacuum-annealed ZrO2 film is much stronger than that from the counterpart with the oxygen-annealed ZrO2 film. This is because the vacuum-annealed ZrO2 film contains more oxygen vacancies and Zr3+ ions. Analysis on the current-voltage characteristic of the ZrO2-based MOS devices indicates the P-F conduction mechanism dominates the electron transportation at the EL-enabling voltages under forward bias. It is tentatively proposed that the recombination of the electrons trapped in multiple oxygen-vacancy-related states with the holes in the defect level pertaining to Zr3+ ions brings about the EL emissions.

Method of removing nitrogen monoxide from a nitrogen monoxide-containing gas using a water-soluble iron ion-dithiocarbamate, xanthate or thioxanthate

DOEpatents

Liu, D. Kwok-Keung; Chang, Shih-Ger

1987-08-25

The present invention relates to a method of removing of nitrogen monoxide from a nitrogen monoxide-containing gas which method comprises contacting a nitrogen oxide-containing gas with an aqueous solution of water soluble organic compound-iron ion chelate complex. The NO absorption efficiency of ferrous urea-dithiocarbamate and ferrous diethanolamine-xanthate as a function of time, oxygen content and solution ph is presented. 3 figs., 1 tab.

Direct Probing of the Dielectric Scavenging-Layer Interface in Oxide Filamentary-Based Valence Change Memory.

PubMed

Celano, Umberto; Op de Beeck, Jonathan; Clima, Sergiu; Luebben, Michael; Koenraad, Paul M; Goux, Ludovic; Valov, Ilia; Vandervorst, Wilfried

2017-03-29

A great improvement in valence change memory performance has been recently achieved by adding another metallic layer to the simple metal-insulator-metal (MIM) structure. This metal layer is often referred to as oxygen exchange layer (OEL) and is introduced between one of the electrodes and the oxide. The OEL is believed to induce a distributed reservoir of defects at the metal-insulator interface thus providing an unlimited availability of building blocks for the conductive filament (CF). However, its role remains elusive and controversial owing to the difficulties to probe the interface between the OEL and the CF. Here, using Scalpel SPM we probe multiple functions of the OEL which have not yet been directly measured, for two popular VCMs material systems: Hf/HfO 2 and Ta/Ta 2 O 5 . We locate and characterize in three-dimensions the volume containing the oxygen exchange layer and the CF with nanometer lateral resolution. We demonstrate that the OEL induces a thermodynamic barrier for the CF and estimate the minimum thickness of the OEL/oxide interface to guarantee the proper switching operations is ca. 3 nm. Our experimental observations are combined to first-principles thermodynamics and defect kinetics to elucidate the role of the OEL for device optimization.

Pettit exercises on the CEVIS

NASA Image and Video Library

2012-03-07

ISS030-E-132542 (7 March 2012) --- NASA astronaut Don Pettit, Expedition 30 flight engineer, performs a VO2max experiment while using the Cycle Ergometer with Vibration Isolation System (CEVIS) in the Destiny laboratory of the International Space Station. VO2max uses the Portable Pulmonary Function System (PPFS), CEVIS, Pulmonary Function System (PFS) gas cylinders and mixing bag system, plus multiple other pieces of hardware to measure oxygen uptake and cardiac output.

Williams with VO2max

NASA Image and Video Library

2012-08-08

ISS032-E-016876 (8 Aug. 2012) --- NASA astronaut Sunita Williams, Expedition 32 flight engineer, performs a VO2max experiment while using the Cycle Ergometer with Vibration Isolation System (CEVIS) in the Destiny laboratory of the International Space Station. VO2max uses the Portable Pulmonary Function System (PPFS), CEVIS, Pulmonary Function System (PFS) gas cylinders and mixing bag system, plus multiple other pieces of hardware to measure oxygen uptake and cardiac output.

Pettit exercises on the CEVIS

NASA Image and Video Library

2012-03-07

ISS030-E-132541 (7 March 2012) --- NASA astronaut Don Pettit, Expedition 30 flight engineer, performs a VO2max experiment while using the Cycle Ergometer with Vibration Isolation System (CEVIS) in the Destiny laboratory of the International Space Station. VO2max uses the Portable Pulmonary Function System (PPFS), CEVIS, Pulmonary Function System (PFS) gas cylinders and mixing bag system, plus multiple other pieces of hardware to measure oxygen uptake and cardiac output.

Detection of reduced interhemispheric cortical communication during task execution in multiple sclerosis patients using functional near-infrared spectroscopy

NASA Astrophysics Data System (ADS)

Jimenez, Jon J.; Yang, Runze; Nathoo, Nabeela; Varshney, Vishal P.; Golestani, Ali-Mohammad; Goodyear, Bradley G.; Metz, Luanne M.; Dunn, Jeff F.

2014-07-01

Multiple sclerosis (MS) impairs brain activity through demyelination and loss of axons. Increased brain activity is accompanied by increases in microvascular hemoglobin oxygen saturation (oxygenation) and total hemoglobin, which can be measured using functional near-infrared spectroscopy (fNIRS). Due to the potentially reduced size and integrity of the white matter tracts within the corpus callosum, it may be expected that MS patients have reduced functional communication between the left and right sides of the brain; this could potentially be an indicator of disease progression. To assess interhemispheric communication in MS, we used fNIRS during a unilateral motor task and the resting state. The magnitude of the change in hemoglobin parameters in the motor cortex was significantly reduced in MS patients during the motor task relative to healthy control subjects. There was also a significant decrease in interhemispheric communication between the motor cortices (expressed as coherence) in MS patients compared to controls during the motor task, but not during the resting state. fNIRS assessment of interhemispheric coherence during task execution may be a useful marker in disorders with white matter damage or axonal loss, including MS.

Computer-aided discovery of a metal-organic framework with superior oxygen uptake.

PubMed

Moghadam, Peyman Z; Islamoglu, Timur; Goswami, Subhadip; Exley, Jason; Fantham, Marcus; Kaminski, Clemens F; Snurr, Randall Q; Farha, Omar K; Fairen-Jimenez, David

2018-04-11

Current advances in materials science have resulted in the rapid emergence of thousands of functional adsorbent materials in recent years. This clearly creates multiple opportunities for their potential application, but it also creates the following challenge: how does one identify the most promising structures, among the thousands of possibilities, for a particular application? Here, we present a case of computer-aided material discovery, in which we complete the full cycle from computational screening of metal-organic framework materials for oxygen storage, to identification, synthesis and measurement of oxygen adsorption in the top-ranked structure. We introduce an interactive visualization concept to analyze over 1000 unique structure-property plots in five dimensions and delimit the relationships between structural properties and oxygen adsorption performance at different pressures for 2932 already-synthesized structures. We also report a world-record holding material for oxygen storage, UMCM-152, which delivers 22.5% more oxygen than the best known material to date, to the best of our knowledge.

Erythrocyte signal transduction pathways, their oxygenation dependence and functional significance.

PubMed

Barvitenko, Nadezhda N; Adragna, Norma C; Weber, Roy E

2005-01-01

Erythrocytes play a key role in human and vertebrate metabolism. Tissue O2 supply is regulated by both hemoglobin (Hb)-O2 affinity and erythrocyte rheology, a key determinant of tissue perfusion. Oxygenation-deoxygenation transitions of Hb may lead to re-organization of the cytoskeleton and signalling pathways activation/deactivation in an O2-dependent manner. Deoxygenated Hb binds to the cytoplasmic domain of the anion exchanger band 3, which is anchored to the cytoskeleton, and is considered a major mechanism underlying the oxygenation-dependence of several erythrocyte functions. This work discusses the multiple modes of Hb-cytoskeleton interactions. In addition, it reviews the effects of Mg2+, 2,3-diphosphoglycerate, NO, shear stress and Ca2+, all factors accompanying the oxygenation-deoxygenation cycle in circulating red cells. Due to the extensive literature on the subject, the data discussed here, pertain mainly to human erythrocytes whose O2 affinity is modulated by 2,3-diphosphoglycerate, ectothermic vertebrate erythrocytes that use ATP, and to bird erythrocytes that use inositol pentaphosphate. Copyright 2005 S. Karger AG, Basel.

Cleaving Off Uranyl Oxygens through Chelation: A Mechanistic Study in the Gas Phase

DOE PAGES

Abergel, Rebecca J.; de Jong, Wibe A.; Deblonde, Gauthier J. -P.; ...

2017-10-11

Recent efforts to activate the strong uranium-oxygen bonds in the dioxo uranyl cation have been limited to single oxo-group activation through either uranyl reduction and functionalization in solution, or by collision induced dissociation (CID) in the gas-phase, using mass spectrometry (MS). Here, we report and investigate the surprising double activation of uranyl by an organic ligand, 3,4,3-LI(CAM), leading to the formation of a formal U 6+ chelate in the gas-phase. The cleavage of both uranyl oxo bonds was experimentally evidence d by CID, using deuterium and 18O isotopic substitutions, and by infrared multiple photon dissociation (IRMPD) spectroscopy. Density functional theorymore » (DFT) computations predict that the overall reaction requires only 132 kJ/mol, with the first oxygen activation entailing about 107 kJ/mol. Here, combined with analysis of similar, but unreactive ligands, these results shed light on the chelation-driven mechanism of uranyl oxo bond cleavage, demonstrating its dependence on the presence of ligand hydroxyl protons available for direct interactions with the uranyl oxygens.« less

Supramolecular nanoreactors for intracellular singlet-oxygen sensitization

NASA Astrophysics Data System (ADS)

Swaminathan, Subramani; Fowley, Colin; Thapaliya, Ek Raj; McCaughan, Bridgeen; Tang, Sicheng; Fraix, Aurore; Burjor, Captain; Sortino, Salvatore; Callan, John F.; Raymo, Françisco M.

2015-08-01

An amphiphilic polymer with multiple decyl and oligo(ethylene glycol) chains attached to a common poly(methacrylate) backbone assembles into nanoscaled particles in aqueous environments. Hydrophobic anthracene and borondipyrromethene (BODIPY) chromophores can be co-encapsulated within the self-assembling nanoparticles and transported across hydrophilic media. The reversible character of the noncovalent bonds, holding the supramolecular containers together, permits the exchange of their components with fast kinetics in aqueous solution. Incubation of cervical cancer (HeLA) cells with a mixture of two sets of nanoparticles, pre-loaded independently with anthracene or BODIPY chromophores, results in guest scrambling first and then transport of co-entrapped species to the intracellular space. Alternatively, incubation of cells with the two sets of nanocarriers in consecutive steps permits the sequential transport of the anthracene and BODIPY chromophores across the plasma membrane and only then allows their co-encapsulation within the same supramolecular containers. Both mechanisms position the two sets of chromophores with complementary spectral overlap in close proximity to enable the efficient transfer of energy intracellularly from the anthracene donors to the BODIPY acceptors. In the presence of iodine substituents on the BODIPY platform, intersystem crossing follows energy transfer. The resulting triplet state can transfer energy further to molecular oxygen with the concomitant production of singlet oxygen to induce cell mortality. Furthermore, the donor can be excited with two near-infrared photons simultaneously to permit the photoinduced generation of singlet oxygen intracellularly under illumination conditions compatible with applications in vivo. Thus, these supramolecular strategies to control the excitation dynamics of multichromophoric assemblies in the intracellular environment can evolve into valuable protocols for photodynamic therapy.An amphiphilic polymer with multiple decyl and oligo(ethylene glycol) chains attached to a common poly(methacrylate) backbone assembles into nanoscaled particles in aqueous environments. Hydrophobic anthracene and borondipyrromethene (BODIPY) chromophores can be co-encapsulated within the self-assembling nanoparticles and transported across hydrophilic media. The reversible character of the noncovalent bonds, holding the supramolecular containers together, permits the exchange of their components with fast kinetics in aqueous solution. Incubation of cervical cancer (HeLA) cells with a mixture of two sets of nanoparticles, pre-loaded independently with anthracene or BODIPY chromophores, results in guest scrambling first and then transport of co-entrapped species to the intracellular space. Alternatively, incubation of cells with the two sets of nanocarriers in consecutive steps permits the sequential transport of the anthracene and BODIPY chromophores across the plasma membrane and only then allows their co-encapsulation within the same supramolecular containers. Both mechanisms position the two sets of chromophores with complementary spectral overlap in close proximity to enable the efficient transfer of energy intracellularly from the anthracene donors to the BODIPY acceptors. In the presence of iodine substituents on the BODIPY platform, intersystem crossing follows energy transfer. The resulting triplet state can transfer energy further to molecular oxygen with the concomitant production of singlet oxygen to induce cell mortality. Furthermore, the donor can be excited with two near-infrared photons simultaneously to permit the photoinduced generation of singlet oxygen intracellularly under illumination conditions compatible with applications in vivo. Thus, these supramolecular strategies to control the excitation dynamics of multichromophoric assemblies in the intracellular environment can evolve into valuable protocols for photodynamic therapy. Electronic supplementary information (ESI) available: Experimental procedures; crystallographic data; absorption and emission spectra; temporal absorbance profiles; singlet-oxygen measurements; intracellular fluorescence measurements; viability assays. See DOI: 10.1039/c5nr02672e

Feed gas contaminant removal in ion transport membrane systems

DOEpatents

Underwood, Richard Paul [Allentown, PA; Makitka, III, Alexander; Carolan, Michael Francis [Allentown, PA

2012-04-03

An oxygen ion transport membrane process wherein a heated oxygen-containing gas having one or more contaminants is contacted with a reactive solid material to remove the one or more contaminants. The reactive solid material is provided as a deposit on a support. The one or more contaminant compounds in the heated oxygen-containing gas react with the reactive solid material. The contaminant-depleted oxygen-containing gas is contacted with a membrane, and oxygen is transported through the membrane to provide transported oxygen.

Microchambers with Solid-State Phosphorescent Sensor for Measuring Single Mitochondrial Respiration.

PubMed

Pham, Ted D; Wallace, Douglas C; Burke, Peter J

2016-07-09

It is now well established that, even within a single cell, multiple copies of the mitochondrial genome may be present (genetic heteroplasmy). It would be interesting to develop techniques to determine if and to what extent this genetic variation results in functional variation from one mitochondrion to the next (functional heteroplasmy). Measuring mitochondrial respiration can reveal the organelles' functional capacity for Adenosine triphosphate (ATP) production and determine mitochondrial damage that may arise from genetic or age related defects. However, available technologies require significant quantities of mitochondria. Here, we develop a technology to assay the respiration of a single mitochondrion. Our "micro-respirometer" consists of micron sized chambers etched out of borofloat glass substrates and coated with an oxygen sensitive phosphorescent dye Pt(II) meso-tetra(pentafluorophenyl)porphine (PtTFPP) mixed with polystyrene. The chambers are sealed with a polydimethylsiloxane layer coated with oxygen impermeable Viton rubber to prevent diffusion of oxygen from the environment. As the mitochondria consume oxygen in the chamber, the phosphorescence signal increases, allowing direct determination of the respiration rate. Experiments with coupled vs. uncoupled mitochondria showed a substantial difference in respiration, confirming the validity of the microchambers as single mitochondrial respirometers. This demonstration could enable future high-throughput assays of mitochondrial respiration and benefit the study of mitochondrial functional heterogeneity, and its role in health and disease.

Cuticular gas exchange by Antarctic sea spiders.

PubMed

Lane, Steven J; Moran, Amy L; Shishido, Caitlin M; Tobalske, Bret W; Woods, H Arthur

2018-04-25

Many marine organisms and life stages lack specialized respiratory structures, like gills, and rely instead on cutaneous respiration, which they facilitate by having thin integuments. This respiratory mode may limit body size, especially if the integument also functions in support or locomotion. Pycnogonids, or sea spiders, are marine arthropods that lack gills and rely on cutaneous respiration but still grow to large sizes. Their cuticle contains pores, which may play a role in gas exchange. Here, we examined alternative paths of gas exchange in sea spiders: (1) oxygen diffuses across pores in the cuticle, a common mechanism in terrestrial eggshells, (2) oxygen diffuses directly across the cuticle, a common mechanism in small aquatic insects, or (3) oxygen diffuses across both pores and cuticle. We examined these possibilities by modeling diffusive oxygen fluxes across all pores in the body of sea spiders and asking whether those fluxes differed from measured metabolic rates. We estimated fluxes across pores using Fick's law parameterized with measurements of pore morphology and oxygen gradients. Modeled oxygen fluxes through pores closely matched oxygen consumption across a range of body sizes, which means the pores facilitate oxygen diffusion. Furthermore, pore volume scaled hypermetrically with body size, which helps larger species facilitate greater diffusive oxygen fluxes across their cuticle. This likely presents a functional trade-off between gas exchange and structural support, in which the cuticle must be thick enough to prevent buckling due to external forces but porous enough to allow sufficient gas exchange. © 2018. Published by The Company of Biologists Ltd.

Reactive Oxygen Species in the Regulation of Synaptic Plasticity and Memory

PubMed Central

Klann, Eric

2011-01-01

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

SANGUINATE (PEGylated Carboxyhemoglobin Bovine): Mechanism of Action and Clinical Update.

PubMed

Abuchowski, Abraham

2017-04-01

Historically, blood substitutes were under development that would provide oxygen carrying capacity as well as fluid replacement for both trauma and surgical indications. Their development was halted by the inability of the products to deliver therapeutic amounts of oxygen targeted to hypoxic tissue as well as from the inherent toxicity of the molecules. This led to the concept of an oxygen therapeutic that would be targeted for indications caused by anemia/ischemia/hypoxia but would not exhibit the toxicity that plagued earlier products. The complex pathophysiology of diseases such as sickle cell and hemorrhagic stroke not only has hypoxia as a pivotal event but also includes inflammation and vasoconstriction that perpetuate the oxygen deprivation. There is a need for an effective therapeutic that addresses the multiple events of inflammation and oxygen deprivation. SANGUINATE acts as a dual mode carbon monoxide (CO) and oxygen delivery therapeutic. SANGUINATE is designed not only to treat hypoxia but also to act on concurrent pathologies such as inflammation and reperfusion injury. This expands the potential therapeutic utility of SANGUINATE beyond anemia into indications such as early brain injury and delayed kidney graft function, where inflammation plays a pivotal pathological role as well as in indications such as sickle cell disease where the inflammation and hypoxia contribute to the development of comorbidities such as vaso-occlusive crisis. Clinical trials in multiple indications are underway. © 2017 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

29 CFR 1910.104 - Oxygen.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., section VII—Unfired Pressure Vessels—1968. Insulation surrounding the liquid oxygen container shall be... in § 1910.6. (iv) Insulation. Insulation casings on liquid oxygen containers shall be equipped with... oxygen and heating medium sections with safety relief devices. (iii) Heating. Heat used in an oxygen...

29 CFR 1910.104 - Oxygen.

Code of Federal Regulations, 2011 CFR

2011-07-01

..., section VII—Unfired Pressure Vessels—1968. Insulation surrounding the liquid oxygen container shall be... in § 1910.6. (iv) Insulation. Insulation casings on liquid oxygen containers shall be equipped with... oxygen and heating medium sections with safety relief devices. (iii) Heating. Heat used in an oxygen...

29 CFR 1910.104 - Oxygen.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., section VII—Unfired Pressure Vessels—1968. Insulation surrounding the liquid oxygen container shall be... in § 1910.6. (iv) Insulation. Insulation casings on liquid oxygen containers shall be equipped with... oxygen and heating medium sections with safety relief devices. (iii) Heating. Heat used in an oxygen...

29 CFR 1910.104 - Oxygen.

Code of Federal Regulations, 2010 CFR

2010-07-01

..., Section VII—Unfired Pressure Vessels—1968. Insulation surrounding the liquid oxygen container shall be... in § 1910.6. (iv) Insulation. Insulation casings on liquid oxygen containers shall be equipped with... oxygen and heating medium sections with safety relief devices. (iii) Heating. Heat used in an oxygen...

29 CFR 1910.104 - Oxygen.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., section VII—Unfired Pressure Vessels—1968. Insulation surrounding the liquid oxygen container shall be... in § 1910.6. (iv) Insulation. Insulation casings on liquid oxygen containers shall be equipped with... oxygen and heating medium sections with safety relief devices. (iii) Heating. Heat used in an oxygen...

Artificial oxygen transport protein

DOEpatents

Dutton, P. Leslie

2014-09-30

This invention provides heme-containing peptides capable of binding molecular oxygen at room temperature. These compounds may be useful in the absorption of molecular oxygen from molecular oxygen-containing atmospheres. Also included in the invention are methods for treating an oxygen transport deficiency in a mammal.

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Generation of singlet oxygen in fullerene-containing media: 1. Photodesorption of singlet oxygen from fullerene-containing surfaces

NASA Astrophysics Data System (ADS)

Belousova, I. M.; Belousov, V. P.; Danilov, O. B.; Ermakov, A. V.; Kiselev, V. M.; Kislyakov, I. M.; Sosnov, E. N.

2008-03-01

It is shown that upon irradiation of fullerene-containing surfaces by laser or flashlamp pulses, oxygen adsorbed by these surfaces efficiently escapes to the gas phase. The observation of luminescence pulses in the spectral region of 762 and 1268 nm confirms the presence of oxygen molecules in the excited singlet state in the desorbed oxygen. The conditions for optimisation of the efficiency of singlet-oxygen production are studied. It is shown that singlet oxygen at the concentration sufficient for obtaining operation of a fullerene-oxygen-iodine laser can be produced in this way.

A Theoretical Basis for the Transition to Denitrification at Nanomolar Oxygen Concentrations

NASA Astrophysics Data System (ADS)

Zakem, E.; Follows, M. J.

2016-02-01

Current climate change is likely to expand the size and intensity of marine oxygen minimum zones. How will this affect denitrification rates? Current global biogeochemical models typically prescribe a critical oxygen concentration below which anaerobic activity occurs, rather than resolve the underlying microbial processes. Here, we explore the dynamics of an idealized, simulated anoxic zone in which multiple prokaryotic metabolisms are resolved mechanistically, defined by redox chemistry and biophysical constraints. We first ask, what controls the critical oxygen concentration governing the favorability of aerobic or anaerobic respiration? The predicted threshold oxygen concentration varies as a function of the environment as well as of cell physiology, and lies within the nanomolar range. The model thus provides a theoretical underpinning for the recent observations of nanomolar oxygen concentrations in oxygen minimum zones. In the context of an idealized, two-dimensional intensified upwelling simulation, we also predict denitrification at oxygen concentrations orders of magnitude higher due to physical mixing, reconciling observations of denitrification over a similar range and demonstrating a decoupling of denitrification from the local oxygen concentration. In a sensitivity study with the idealized ocean model, we comment upon the relationship between the volume of anoxic waters and total denitrification.

Study of the tritium behavior on the surface of Li 2O by means of work function measurement

NASA Astrophysics Data System (ADS)

Yokota, Toshihiko; Suzuki, Atsushi; Yamaguchi, Kenji; Terai, Takayuki; Yamawaki, Michio

2000-12-01

In the present study, the work function change of Li 2O due to change of oxygen potential of sweep gas was investigated by measuring the contact potential difference (CPD) between Li 2O and Pt electrodes with a so-called `high temperature Kelvin probe'. The CPD change for Li 2O was generally insensitive to the oxygen partial pressure in the sweep gas. A similar insensitivity was also observed for LiAlO 2. Although the CPD change of Li 2O was about 200 mV when the oxygen partial pressure was changed by as much as 15 orders of magnitude, such was not the case for LiAlO 2. By comparing with the results obtained for other Li-bearing ceramics, it was estimated to be caused by the adsorption/desorption processes of water vapor contained in the sweep gas.

Polymer blend compositions and methods of preparation

DOEpatents

Naskar, Amit K.

2016-09-27

A polymer blend material comprising: (i) a first polymer containing hydrogen bond donating groups having at least one hydrogen atom bound to a heteroatom selected from oxygen, nitrogen, and sulfur, or an anionic version of said first polymer wherein at least a portion of hydrogen atoms bound to a heteroatom is absent and replaced with at least one electron pair; (ii) a second polymer containing hydrogen bond accepting groups selected from nitrile, halogen, and ether functional groups; and (iii) at least one modifying agent selected from carbon particles, ether-containing polymers, and Lewis acid compounds; wherein, if said second polymer contains ether functional groups, then said at least one modifying agent is selected from carbon particles and Lewis acid compounds. Methods for producing the polymer blend, molded forms thereof, and articles thereof, are also described.

Density Functional Theory Calculations of the Quantum Capacitance of Graphene Oxide as a Supercapacitor Electrode.

PubMed

Song, Ce; Wang, Jinyan; Meng, Zhaoliang; Hu, Fangyuan; Jian, Xigao

2018-03-31

Graphene oxide has become an attractive electrode-material candidate for supercapacitors thanks to its higher specific capacitance compared to graphene. The quantum capacitance makes relative contributions to the specific capacitance, which is considered as the major limitation of graphene electrodes, while the quantum capacitance of graphene oxide is rarely concerned. This study explores the quantum capacitance of graphene oxide, which bears epoxy and hydroxyl groups on its basal plane, by employing density functional theory (DFT) calculations. The results demonstrate that the total density of states near the Fermi level is significantly enhanced by introducing oxygen-containing groups, which is beneficial for the improvement of the quantum capacitance. Moreover, the quantum capacitances of the graphene oxide with different concentrations of these two oxygen-containing groups are compared, revealing that more epoxy and hydroxyl groups result in a higher quantum capacitance. Notably, the hydroxyl concentration has a considerable effect on the capacitive behavior. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fabrication of hierarchical core-shell polydopamine@MgAl-LDHs composites for the efficient enrichment of radionuclides

NASA Astrophysics Data System (ADS)

Zhu, Kairuo; Lu, Songhua; Gao, Yang; Zhang, Rui; Tan, Xiaoli; Chen, Changlun

2017-02-01

Novel hierarchical core/shell structured polydopamine@MgAl-layered double hydroxides (PDA@MgAl-LDHs) composites involving MgAl-layered double hydroxide shells and PDA cores were fabricated thought one-pot coprecipitation assembly and methodically characterized by X-ray diffraction, Fourier transformed infrared spectroscopy, scanning/transmission electron microscopy, selected area electron diffraction, elemental mapping, thermogravimetric analysis and X-ray photoelectron spectroscopy technologies. U(VI) and Eu(III) sorption experiments showed that the PDA@MgAl-LDHs exhibited higher sorption ability with a maximum sorption capacity of 142.86 and 76.02 mg/g at 298 K and pH 4.5, respectively. More importantly, according to XPS analyses, U(VI) and Eu(III) were sorbed on PDA@MgAl-LDHs via oxygen-containing functional groups, and the chemical affinity of U(VI) by oxygen-containing functional groups is higher than that of Eu(III). These observations show great expectations in the enrichment of radionuclides from aquatic environments by PDA@MgAl-LDHs.

Enhanced Heme Function and Mitochondrial Respiration Promote the Progression of Lung Cancer Cells

PubMed Central

Alam, Md Maksudul; Shah, Ajit; Cao, Thai M.; Sullivan, Laura A.; Brekken, Rolf; Zhang, Li

2013-01-01

Lung cancer is the leading cause of cancer-related mortality, and about 85% of the cases are non-small-cell lung cancer (NSCLC). Importantly, recent advance in cancer research suggests that altering cancer cell bioenergetics can provide an effective way to target such advanced cancer cells that have acquired mutations in multiple cellular regulators. This study aims to identify bioenergetic alterations in lung cancer cells by directly measuring and comparing key metabolic activities in a pair of cell lines representing normal and NSCLC cells developed from the same patient. We found that the rates of oxygen consumption and heme biosynthesis were intensified in NSCLC cells. Additionally, the NSCLC cells exhibited substantially increased levels in an array of proteins promoting heme synthesis, uptake and function. These proteins include the rate-limiting heme biosynthetic enzyme ALAS, transporter proteins HRG1 and HCP1 that are involved in heme uptake, and various types of oxygen-utilizing hemoproteins such as cytoglobin and cytochromes. Several types of human tumor xenografts also displayed increased levels of such proteins. Furthermore, we found that lowering heme biosynthesis and uptake, like lowering mitochondrial respiration, effectively reduced oxygen consumption, cancer cell proliferation, migration and colony formation. In contrast, lowering heme degradation does not have an effect on lung cancer cells. These results show that increased heme flux and function are a key feature of NSCLC cells. Further, increased generation and supply of heme and oxygen-utilizing hemoproteins in cancer cells will lead to intensified oxygen consumption and cellular energy production by mitochondrial respiration, which would fuel cancer cell proliferation and progression. The results show that inhibiting heme and respiratory function can effectively arrest the progression of lung cancer cells. Hence, understanding heme function can positively impact on research in lung cancer biology and therapeutics. PMID:23704904

Identification of a flavin-containing S-oxygenating monooxygenase involved in alliin biosynthesis in garlic.

PubMed

Yoshimoto, Naoko; Onuma, Misato; Mizuno, Shinya; Sugino, Yuka; Nakabayashi, Ryo; Imai, Shinsuke; Tsuneyoshi, Tadamitsu; Sumi, Shin-ichiro; Saito, Kazuki

2015-09-01

S-Alk(en)yl-l-cysteine sulfoxides are cysteine-derived secondary metabolites highly accumulated in the genus Allium. Despite pharmaceutical importance, the enzymes that contribute to the biosynthesis of S-alk-(en)yl-l-cysteine sulfoxides in Allium plants remain largely unknown. Here, we report the identification of a flavin-containing monooxygenase, AsFMO1, in garlic (Allium sativum), which is responsible for the S-oxygenation reaction in the biosynthesis of S-allyl-l-cysteine sulfoxide (alliin). Recombinant AsFMO1 protein catalyzed the stereoselective S-oxygenation of S-allyl-l-cysteine to nearly exclusively yield (RC SS )-S-allylcysteine sulfoxide, which has identical stereochemistry to the major natural form of alliin in garlic. The S-oxygenation reaction catalyzed by AsFMO1 was dependent on the presence of nicotinamide adenine dinucleotide phosphate (NADPH) and flavin adenine dinucleotide (FAD), consistent with other known flavin-containing monooxygenases. AsFMO1 preferred S-allyl-l-cysteine to γ-glutamyl-S-allyl-l-cysteine as the S-oxygenation substrate, suggesting that in garlic, the S-oxygenation of alliin biosynthetic intermediates primarily occurs after deglutamylation. The transient expression of green fluorescent protein (GFP) fusion proteins indicated that AsFMO1 is localized in the cytosol. AsFMO1 mRNA was accumulated in storage leaves of pre-emergent nearly sprouting bulbs, and in various tissues of sprouted bulbs with green foliage leaves. Taken together, our results suggest that AsFMO1 functions as an S-allyl-l-cysteine S-oxygenase, and contributes to the production of alliin both through the conversion of stored γ-glutamyl-S-allyl-l-cysteine to alliin in storage leaves during sprouting and through the de novo biosynthesis of alliin in green foliage leaves. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.

Electrode influence on the number of oxygen vacancies at the gate/high-κ dielectric interface in nanoscale MIM capacitors

NASA Astrophysics Data System (ADS)

Stojanovska-Georgievska, Lihnida

2015-02-01

In this paper, a particular attention has been paid in determining the impact of the type of top electrode (the gate), on the overall characteristics of the examined metal-insulator-metal structures, that contain doped Ta2O5:Hf high-κ dielectric as an insulator. For that purpose MIM capacitors with different metal gates (conventional Al and also W, Au, Pt, Mo, TiN, Ta) were formed. The results obtained, consider both the influence of metal work function and oxygen affinity, as possible reasons for increasing of number of oxygen vacancies at the gate/dielectric interface. Here we use capacitance-voltage alteration (C-V measurements) under constant current stress (CCS) conditions as characterization technique. The measurements show grater creation of positive oxygen vacancies in the case of metal electrodes with high work function, like Au and Pt, for almost one order of magnitude. It is also indicative that these metals have also the lowest values of heat of oxygen formation, which also favors the creation of oxygen vacancies. All results are discussed taking into consideration the nanoscale thickness of the dielectric layer (of the order of 8 nm), implicating the stronger effect of interface properties on the overall behavior rather than the one originating from the bulk of material.

Hypoxic Regulation of Functional Extracellular Matrix Elaboration by Nucleus Pulposus Cells in Long-Term Agarose Culture

PubMed Central

Gorth, Deborah J; Lothstein, Katherine E; Chiaro, Joseph A; Farrell, Megan J; Dodge, George R; Elliott, Dawn M; Malhotra, Neil R; Mauck, Robert L; Smith, Lachlan J

2015-01-01

Degeneration of the intervertebral discs is strongly implicated as a cause of low back pain. Since current treatments for discogenic low back pain show poor long-term efficacy, a number of new, biological strategies are being pursued. For such therapies to succeed, it is critical that they be validated in conditions that mimic the unique biochemical microenvironment of the nucleus pulposus (NP), which include low oxygen tension. Therefore, the objective of this study was to investigate the effects of oxygen tension on NP cell functional extracellular matrix elaboration in 3D culture. Bovine NP cells were encapsulated in agarose constructs and cultured for 14 or 42 days in either 20% or 2% oxygen in defined media containing transforming growth factor beta-3. At each time point, extracellular matrix composition, biomechanics and mRNA expression of key phenotypic markers were evaluated. Results showed that while bulk mechanics and composition were largely independent of oxygen level, low oxygen promoted improved restoration of the NP phenotype, higher mRNA expression of extracellular matrix and NP specific markers, and more uniform matrix elaboration. These findings indicate that culture under physiological oxygen levels is an important consideration for successful development of cell and growth factor-based regenerative strategies for the disc. PMID:25640328

Low temperature hydrolysis of laboratory tholins in ammonia-water solutions: Implications for prebiotic chemistry on Titan

NASA Astrophysics Data System (ADS)

Neish, Catherine D.; Somogyi, Árpád; Lunine, Jonathan I.; Smith, Mark A.

2009-05-01

Laboratory tholins react rapidly in 13 wt% ammonia-water at low temperature, producing complex organic molecules containing both oxygen and altered nitrogen functional groups. These reactions display first-order kinetics with half-lives between 0.3 and 14 days at 253 K. The reaction timescales are much shorter than the freezing timescales of impact melts and volcanic sites on Titan, providing ample time for the formation of oxygenated, possibly prebiotic, molecules on its surface. Comparing the rates of the hydrolysis reactions in ammonia-water to those measured in pure water [Neish, C.D, Somogyi, A., Imanaka, H., Lunine, J.I., Smith, M.A., 2008a. Astrobiology 8, 273-287], we find that incorporation of oxygen into the tholins is faster in the presence of ammonia. The rate increases could be due to the increased pH of the solution, or to the availability of new reaction pathways made possible by the presence of ammonia. Using labeled 15NH 3 water, we find that ammonia does incorporate into some products, and that the reactions with ammonia are largely independent of those with water. A related study in HO18 confirms water as the source of the oxygen incorporated into the oxygen containing products.

Highly Oxygenated Multifunctional Compounds in α-Pinene Secondary Organic Aerosol.

PubMed

Zhang, Xuan; Lambe, Andrew T; Upshur, Mary Alice; Brooks, William A; Gray Bé, Ariana; Thomson, Regan J; Geiger, Franz M; Surratt, Jason D; Zhang, Zhenfa; Gold, Avram; Graf, Stephan; Cubison, Michael J; Groessl, Michael; Jayne, John T; Worsnop, Douglas R; Canagaratna, Manjula R

2017-06-06

Highly oxygenated multifunctional organic compounds (HOMs) originating from biogenic emissions constitute a widespread source of organic aerosols in the pristine atmosphere. However, the molecular forms in which HOMs are present in the condensed phase upon gas-particle partitioning remain unclear. In this study, we show that highly oxygenated molecules that contain multiple peroxide functionalities are readily cationized by the attachment of Na + during electrospray ionization operated in the positive ion mode. With this method, we present the first identification of HOMs characterized as C 8-10 H 12-18 O 4-9 monomers and C 16-20 H 24-36 O 8-14 dimers in α-pinene derived secondary organic aerosol (SOA). Simultaneous detection of these molecules in the gas phase provides direct evidence for their gas-to-particle conversion. Molecular properties of particulate HOMs generated from ozonolysis and OH oxidation of unsubstituted (C 10 H 16 ) and deuterated (C 10 H 13 D 3 ) α-pinene are investigated using coupled ion mobility spectrometry with mass spectrometry. The systematic shift in the mass of monomers in the deuterated system is consistent with the decomposition of isomeric vinylhydroperoxides to release vinoxy radical isotopologues, the precursors to a sequence of autoxidation reactions that ultimately yield HOMs in the gas phase. The remarkable difference observed in the dimer abundance under O 3 - versus OH-dominant environments underlines the competition between intramolecular hydrogen migration of peroxy radicals and their bimolecular termination reactions. Our results provide new and direct molecular-level information for a key component needed for achieving carbon mass closure of α-pinene SOA.

Purinergic effects of a hydroalcoholic Agaricus brasiliensis (A. blazei) extract on liver functions.

PubMed

de Oliveira, Andrea L; Eler, G Jacklin; Bracht, Adelar; Peralta, Rosane M

2010-06-23

The effects of a hydroalcoholic extract of Agaricus brasiliensis (A. blazei) on functional parameters in the perfused rat liver were examined with emphasis on its content of nucleotides and nucleosides. Several nucleosides and nucleotides were identified in the A. brasiliensis extract, which was active on several liver functions. A significant part of the effects is the result of the purinergic action of nucleosides and nucleotides: pressure increment, glycogenolysis stimulation, transient inhibition of oxygen consumption, and redox state changes. Other phenomena such as the stimulation of gluconeogenesis, ureogenesis, and oxygen consumption are more likely consequences of the metabolic transformation of substrates contained within the extract, especially amino acids. It seems apparent that consumption of A. brasiliensis represents not only the ingestion of metabolic precursors but also the ingestion of substances that, even at low concentrations, can exert important signaling functions in the liver as well as in the organism as a whole.

Optimization measurement of muscle oxygen saturation under isometric studies using FNIRS

NASA Astrophysics Data System (ADS)

Halim, A. A. A.; Laili, M. H.; Salikin, M. S.; Rusop, M.

2018-05-01

Development of functional near infrared spectroscopy (fNIRS) technologies has advanced quantification signal using multiple wavelength and detector to investigate hemodynamic response in human muscle. These non-invasive technologies have been widely used to solve the propagation of light inside the tissues including the absorption, scattering coefficient and to quantify the oxygenation level of haemoglobin and myoglobin in human muscle. The goal of this paper is to optimize the measurement of muscle oxygen saturation during isometric exercise using functional near infrared spectroscopy (fNIRS). The experiment was carried out on 15 sedentary healthy male volunteers. All volunteers are required to perform an isometric exercise at three assessment of muscular fatigue's level on flexor digitalis (FDS) muscle in the human forearm using fNIRS. The slopes of the signals have been highlighted to evaluate the muscle oxygen saturation of regional muscle fatigue. As a result, oxygen saturation slope from 10% exercise showed steeper than the first assessment at 30%-50% of fatigues level. The hemodynamic signal response showed significant value (p=0.04) at all three assessment of muscular fatigue's level which produce a p-value (p<0.05) measured by fNIRS. Thus, this highlighted parameter could be used to estimate fatigue's level of human and could open other possibilities to study muscle performance diagnosis.

Molecular Structures and Sorption Mechanisms of Biochars as Heterogeneous Carbon Materials

NASA Astrophysics Data System (ADS)

Chen, Baoliang; Chen, Zaiming; Xiao, Xin; Fang, Qile

2015-04-01

Surface functional groups such as carboxyl play a vital role in the environmental applications of biochar as a soil amendment. However, the quantification of oxygen-containing groups on a biochar surface still lacks systematical investigation. An integrated method combining chemical and spectroscopic techniques was established to quantitatively identify the chemical states, dissociation constants (pKa), and contents of oxygen-containing groups on dairy manure-derived biochars prepared at 100-700 °C. The dissociation pH of carboxyl groups on the biochar surface covered a wide range of pH values (pH 2-11), due to the varied structural micro-environments and chemical states. For low temperature biochars (≤350 °C), carboxyl existed not only as hydrogen-bonded carboxyl and unbonded carboxyl groups but also formed esters at the surface of biochars. The esters consumed OH‒ via saponification in the alkaline pH region and enhanced the dissolution of organic matter from biochars. For high temperature biochars (≥500 °C), esters came from carboxyl were almost eliminated via carbonization (ester pyrolysis), while lactones were developed. The surface density of carboxyl groups on biochars decreased sharply with the increase of the biochar-producing temperature, but the total contents of the surface carboxyls for different biochars were comparable (with a difference < 3-fold) as a result of the expanded surface area at high pyrolytic temperatures. Understanding the wide pKa ranges and the abundant contents of carboxyl groups on biochars is a prerequisite to recognition of the multi-functional applications and biogeochemical cycling of biochars. A schematic diagram for the dissociation of acid/base groups on biochar surfaces and their related functions was depicted. The protonated biochars favor inorganic anion adsorption and ionizable organic chemical sorption, while the deprotonated biochars favor cationic nutrient retention, heavy metal immobilization, and the release of dissolved materials. For low temperature biochars (i.e., DM100, DM250 and DM350), the acid/base group dissociation directly controls the pH buffering properties of biochars. The resulting surface charges regulate biochars in nutrient retention, sorption/immobilization of hazardous pollutants and biochar particle dispersing properties. Meanwhile, dissociation of acid/base groups affects carbon and silica biogeochemical cycling by regulating the release of organic matter from the cleavage of esters and dissolution of the Si-containing minerals. For high temperature biochars (i.e., DM500 and DM700), the effect of acid/base dissociation on organic matter dissolution is eliminated, but other functions are similar. CGs are the major acid/base groups on biochar surfaces. In field applications, such abundant CGs are worthy of concern in terms of multiple functions of biochars, such as soil pH adjustment, soil nutrient retention, and toxic metals immobilization.

Vacuum-based surface modification of organic and metallic substrates

NASA Astrophysics Data System (ADS)

Torres, Jessica

Surface physico-chemical properties play an important role in the development and performance of materials in different applications. Consequently, understanding the chemical and physical processes involved during surface modification strategies is of great scientific and technological importance. This dissertation presents results from the surface modification of polymers, organic films and metallic substrates with reactive species, with the intent of simulating important modification processes and elucidating surface property changes of materials under different environments. The reactions of thermally evaporated copper and titanium with halogenated polytetrafluoroethylene (PTFE) and polyvinyl chloride (PVC) are used to contrast the interaction of metals with polymers. Results indicate that reactive metallization is thermodynamically favored when the metal-halogen bond strength is greater than the carbon-halogen bond strength. X-ray post-metallization treatment results in an increase in metal-halide bond formation due to the production of volatile halogen species in the polymer that react with the metallic overlayer. The reactions of atomic oxygen (AO) and atomic chlorine with polyethylene (PE) and self-assembled monolayers (SAMs) films were followed to ascertain the role of radical species during plasma-induced polymer surface modification. The reactions of AO with X-ray modified SAMs are initially the dominated by the incorporation of new oxygen containing functionality at the vacuum/film interface, leading to the production of volatile carbon containing species such as CO2 that erodes the hydrocarbon film. The reaction of atomic chlorine species with hydrocarbon SAMs, reveals that chlorination introduces C-Cl and C-Cl2 functionalities without erosion. A comparison of the reactions of AO and atomic chlorine with PE reveal a maximum incorporation of the corresponding C-O and C-Cl functionalities at the polymer surface. A novel method to prepare phosphorous-containing polymer surfaces through ion implantation of trimethyl phosphine onto PE is presented. Air exposure of the resulting P-implanted PE leads to the surface selective oxidation of phosphorous moieties. P-containing hydrocarbon films are used to model the surface chemical changes of P-containing polymers exposed to AO. Results indicate that oxidized phosphorous species protect the film from AO-induced erosion. The low temperature (<150 K) oxidation of nitrided iron surfaces exposed to oxygen reveal the formation of iron oxynitride (FexNyO z, nitrosonium ions (NO+) as well as nitrite/nitrito and nitrate type species. The production of nitrite/nitrito and nitrate species is taken as evidence for the existence of oxygen insertion chemistry into the iron nitride lattice under these low temperature oxidation conditions. Upon annealing the oxidized iron nitride surface, nitrogen desorbs exclusively as nitric oxide (NO).

Purification, crystallization and preliminary crystallographic studies of haemoglobin from mongoose (Helogale parvula) in two different crystal forms induced by pH variation.

PubMed

Mohamed Abubakkar, M; Saraboji, K; Ponnuswamy, M N

2013-02-01

Haemoglobin (Hb) is a respiratory pigment; it is a tetrameric protein that ferries oxygen from the lungs to tissues and transports carbon dioxide on the return journey. The oxygen affinity of haemoglobin is regulated by the concentration of oxygen surrounding it and several efforts have revealed the shapes of Hb in different states and with different functions. However, study of the molecular basis of Hbs from low-oxygen-affinity species is critically needed in order to increase the understanding of the mechanism behind oxygen adaptation. The present study reports the preliminary crystallographic study of low-oxygen-affinity haemoglobin from mongoose, a burrowing mammal. Haemoglobin from mongoose was purified by anion-exchange chromatography, crystallized using the hanging-drop vapour-diffusion method and diffraction data sets were collected from monoclinic (2.3 Å resolution) and orthorhombic (2.9 Å resolution) crystal forms obtained by pH variation. The monoclinic and orthorhombic asymmetric units contained half and a whole biological molecule, respectively.

Resolving phase stability in the Ti-O binary with first-principles statistical mechanics methods

NASA Astrophysics Data System (ADS)

Gunda, N. S. Harsha; Puchala, Brian; Van der Ven, Anton

2018-03-01

The Ti-O system consists of a multitude of stable and metastable oxides that are used in wide ranging applications. In this work we investigate phase stability in the Ti-O binary from first principles. We perform a systematic search for ground state structures as a function of oxygen concentration by considering oxygen-vacancy and/or titanium-vacancy orderings over four parent crystal structures: (i) hcp Ti, (ii) ω -Ti, (iii) rocksalt, and (iv) hcp oxygen containing interstitial titanium. We explore phase stability at finite temperature using cluster expansion Hamiltonians and Monte Carlo simulations. The calculations predict a high oxygen solubility in hcp Ti and the stability of suboxide phases that undergo order-disorder transitions upon heating. Vacancy ordered rocksalt phases are also predicted at low temperature that disorder to form an extended solid solution at high temperatures. Predicted stable and metastable phase diagrams are qualitatively consistent with experimental observations, however, important discrepancies are revealed between first-principles density functional theory predictions of phase stability and the current understanding of phase stability in this system.

Functionalization of Single-Wall Carbon Nanotubes by Photo-Oxidation

NASA Technical Reports Server (NTRS)

Lebron-Colon, Marisabel; Meador, Michael A.

2010-01-01

new technique for carbon nanotube oxidation was developed based upon the photo-oxidation of organic compounds. The resulting method is more benign than conventional oxidation approaches and produces single-wall carbon nanotubes (SWCNTs) with higher levels of oxidation. In this procedure, an oxygen saturated suspension of SWNTs in a suitable solvent containing a singlet oxygen sensitizer, such as Rose Bengal, is irradiated with ultraviolet light. The resulting oxidized tubes are recovered by filtering the suspension, followed by washing to remove any adsorbed solvent and sensitizer, and drying in a vacuum oven. Chemical analysis by FT-infrared and x-ray photoelectron spectroscopy revealed that the oxygen content of the photo-oxidized SWCNT was 11.3 atomic % compared to 6.7 atomic % for SWCNT that had been oxidized by standard treatment in refluxing acid. The photo-oxidized SWCNT produced by this method can be used directly in various polymer matrixes, or can be further modified by chemical reactions at the oxygen functional groups and then used as additives. This method may also be suitable for use in oxidation of multiwall carbon nanotubes and graphenes.

Oxygen partial pressure influenced structural and optical properties of DC magnetron sputtered ZrO{sub 2} films

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

Kondaiah, P.; Madhavi, V.; Uthanna, S.

2013-02-05

Thin films of zirconium oxide (ZrO{sub 2}) were deposited on (100) p-silicon and quartz substrates by sputtering of metallic zirconium target under different oxygen partial pressures in the range 8 Multiplication-Sign 10{sup -3}-6 Multiplication-Sign 10{sup -2}Pa. The effect of oxygen partial pressure on the structural and optical properties of the deposited films was systematically investigated. The deposition rate of the films decreased from 3.3 to 1.83 nm/min with the increase of oxygen partial pressure from 8 Multiplication-Sign 10{sup -3}-6 Multiplication-Sign 10{sup -2}Pa respectively. The X-ray diffraction profiles revealed that the films exhibit (111) refection of zirconium oxide in monoclinic phase.more » The optical band gap of the films increased from 5.62 to 5.80 eV and refractive index increased from 2.01 to 2.08 with the increase of oxygen partial pressure from 8 Multiplication-Sign 10{sup -3}-6 Multiplication-Sign 10{sup -2}Pa respectively.« less

Solubility of copper in silicate melts as function of oxygen and sulfur fugacities, temperature, and silicate composition

NASA Astrophysics Data System (ADS)

Holzheid, A.; Lodders, K.

2001-06-01

The solubility of Cu in silicate melts coexisting with liquid Cu(Fe) metal and liquid Cu(Fe) sulfide was determined experimentally at oxygen fugacities ranging from 10 -9.1 to 10 -13.6 bar and sulfur fugacities ranging from 10 -2.5 to 10 -6.3 bar at 1300°C. An iron oxide-free silicate of anorthite-diopside eutectic composition and a synthetic MgO-rich basaltic silicate (FeO-bearing) were used in the partitioning experiments. In S-containing systems, some of the metal reacted to metal sulfide. The silicates in the four systems investigated (Fe-free and S-free; Fe-containing and S-free; Fe-free and S-containing; Fe-containing and S-containing) had different colors depending on the dissolved Cu species and the presence of iron and/or sulfur. Irrespective of the presence of sulfur, the solubility of Cu in the silicate increases with increasing oxygen fugacity and metal/silicate partition coefficients for Cu decrease. Increasing the temperature from 1300°C to 1514°C increases the Cu solubility (decreases the metal/silicate partition coefficient) at an oxygen fugacity 0.5 log units below the iron-wüstite (IW) equilibrium in the Fe-free, S-free and Fe-containing, S-free systems. We infer the presence of monovalent Cu + ("CuO 0.5") in the silicate melt on the basis of the solubility of Cu as function of oxygen fugacity. Experiments containing iron yield a formal valence of ˜0.5 for Cu at very low oxygen fugacities, which is not observed in Fe-free systems. The low formal valence is explained by redox reactions between iron and copper in the silicate melts. There is no evidence for sulfidic dissolution of Cu in the silicates but sulfur has indirect effects on Cu partitioning. Iron metal/silicate partition coefficients depend on oxygen fugacity and on sulfur fugacity. Sulfidic dissolution of iron and oxide-sulfide exchange reactions with Cu cause a small increase in Cu metal/silicate partition coefficients. We derive an activity coefficient (γ CuO 0.5) of 10 ± 1 for liquid CuO 0.5 at 1300°C for the silicate melts used here. A comparison with literature data shows that log γ CuO 0.5 increases in proportion to the mass percentages [CaO +(Al 2O 3)/2] in silicate melts. We recommend the following equations for Cu metal/silicate and sulfide/silicate partitioning for geochemical and cosmochemical modeling if silicate composition and the activity of Cu in the metal or sulfide is known: log D met/sil = -0.48 - 0.25 · log fO 2 - log γ Cu metal + 0.02 · [CaO + (Al 2O 3)/2; wt%] silicate logD sul/sil=+0.76-0.25 · logfO 2+0.25logfS 2-logγ CS 0.5,sulfide +0.02 · [CaO+Al 2O 3/2;wt%] silicate. The derived Cu metal/silicate and metal/sulfide partition coefficients are applied to core formation in the Earth and Mars. The observed Cu abundances in the Earth cannot be easily explained by simple core-mantle equilibrium, but the observed Cu abundances for Mars are consistent with core-mantle equilibrium at low pressure and temperatures.

(1)H, (13)C, (15)N backbone and side-chain resonance assignment of Nostoc sp. C139A variant of the heme-nitric oxide/oxygen binding (H-NOX) domain.

PubMed

Alexandropoulos, Ioannis I; Argyriou, Aikaterini I; Marousis, Kostas D; Topouzis, Stavros; Papapetropoulos, Andreas; Spyroulias, Georgios A

2016-10-01

The H-NOX (Heme-nitric oxide/oxygen binding) domain is conserved across eukaryotes and bacteria. In human soluble guanylyl cyclase (sGC) the H-NOX domain functions as a sensor for the gaseous signaling agent nitric oxide (NO). sGC contains the heme-binding H-NOX domain at its N-terminus, which regulates the catalytic site contained within the C-terminal end of the enzyme catalyzing the conversion of GTP (guanosine 5'-triphosphate) to GMP (guanylyl monophosphate). Here, we present the backbone and side-chain assignments of the (1)H, (13)C and (15)N resonances of the 183-residue H-NOX domain from Nostoc sp. through solution NMR.

A Wheat WRKY Transcription Factor TaWRKY10 Confers Tolerance to Multiple Abiotic Stresses in Transgenic Tobacco

PubMed Central

Chen, Liulin; Wang, Xiatian; Ma, Hui; Hu, Wei; Yao, Ningcong; Feng, Ying; Chai, Ruihong; Yang, Guangxiao; He, Guangyuan

2013-01-01

WRKY transcription factors are reported to be involved in defense regulation, stress response and plant growth and development. However, the precise role of WRKY transcription factors in abiotic stress tolerance is not completely understood, especially in crops. In this study, we identified and cloned 10 WRKY genes from genome of wheat (Triticum aestivum L.). TaWRKY10, a gene induced by multiple stresses, was selected for further investigation. TaWRKY10 was upregulated by treatment with polyethylene glycol, NaCl, cold and H2O2. Result of Southern blot indicates that the wheat genome contains three copies of TaWRKY10. The TaWRKY10 protein is localized in the nucleus and functions as a transcriptional activator. Overexpression of TaWRKY10 in tobacco (Nicotiana tabacum L.) resulted in enhanced drought and salt stress tolerance, mainly demonstrated by the transgenic plants exhibiting of increased germination rate, root length, survival rate, and relative water content under these stress conditions. Further investigation showed that transgenic plants also retained higher proline and soluble sugar contents, and lower reactive oxygen species and malonaldehyde contents. Moreover, overexpression of the TaWRKY10 regulated the expression of a series of stress related genes. Taken together, our results indicate that TaWRKY10 functions as a positive factor under drought and salt stresses by regulating the osmotic balance, ROS scavenging and transcription of stress related genes. PMID:23762295

IDENTIFICATION AND QUANTIFICATION OF AEROSOL POLAR OXYGENATED COMPOUNDS BEARING CARBOXYLIC AND/OR HYDROXYL GROUPS. 1. METHOD DEVELOPMENT

EPA Science Inventory

In this study, a new analytical technique was developed for the identification and quantification of multi-functional compounds containing simultaneously at least one hydroxyl or one carboxylic group, or both. This technique is based on derivatizing first the carboxylic group(s) ...

Key Elements of the Chemistry of Cytochrome P-450: The Oxygen Rebound Mechanism.

ERIC Educational Resources Information Center

Groves, John T.

1985-01-01

Discusses the structure and function of the liver protein cytochrome P-450, an important catalyst for a variety of detoxification reactions. Diagnostic substracts for this heme-containing monooxygenase, synthetic modes of the active site, and oxidations with synthetic metalloporphyrins are the major topic areas considered. (JN)

Analysis of regional brain mitochondrial bioenergetics and susceptibility to mitochondrial inhibition utilizing a microplate based system

PubMed Central

Sauerbeck, Andrew; Pandya, Jignesh; Singh, Indrapal; Bittman, Kevin; Readnower, Ryan; Bing, Guoying; Sullivan, Patrick

2012-01-01

The analysis of mitochondrial bioenergetic function typically has required 50–100 μg of protein per sample and at least 15 min per run when utilizing a Clark-type oxygen electrode. In the present work we describe a method utilizing the Seahorse Biosciences XF24 Flux Analyzer for measuring mitochondrial oxygen consumption simultaneously from multiple samples and utilizing only 5 μg of protein per sample. Utilizing this method we have investigated whether regionally based differences exist in mitochondria isolated from the cortex, striatum, hippocampus, and cerebellum. Analysis of basal mitochondrial bioenergetics revealed that minimal differences exist between the cortex, striatum, and hippocampus. However, the cerebellum exhibited significantly slower basal rates of Complex I and Complex II dependent oxygen consumption (p < 0.05). Mitochondrial inhibitors affected enzyme activity proportionally across all samples tested and only small differences existed in the effect of inhibitors on oxygen consumption. Investigation of the effect of rotenone administration on Complex I dependent oxygen consumption revealed that exposure to 10 pM rotenone led to a clear time dependent decrease in oxygen consumption beginning 12 min after administration (p < 0.05). These studies show that the utilization of this microplate based method for analysis of mitochondrial bioenergetics is effective at quantifying oxygen consumption simultaneously from multiple samples. Additionally, these studies indicate that minimal regional differences exist in mitochondria isolated from the cortex, striatum, or hippocampus. Furthermore, utilization of the mitochondrial inhibitors suggests that previous work indicating regionally specific deficits following systemic mitochondrial toxin exposure may not be the result of differences in the individual mitochondria from the affected regions. PMID:21402103

Self-Monitoring Checklists for Inquiry Problem-Solving: Functional Problem-Solving Methods for Students with Intellectual Disability

ERIC Educational Resources Information Center

Miller, Bridget; Taber-Doughty, Teresa

2014-01-01

Three students with mild to moderate intellectual and multiple disability, enrolled in a self-contained functional curriculum class were taught to use a self-monitoring checklist and science notebook to increase independence in inquiry problem-solving skills. Using a single-subject multiple-probe design, all students acquired inquiry…

Unifying theoretical framework for deciphering the oxygen reduction reaction on platinum.

PubMed

Huang, Jun; Zhang, Jianbo; Eikerling, Michael

2018-05-07

Rapid conversion of oxygen into water is crucial to the operation of polymer electrolyte fuel cells and other emerging electrochemical energy technologies. Chemisorbed oxygen species play double-edged roles in this reaction, acting as vital intermediates on one hand and site-blockers on the other. Any attempt to decipher the oxygen reduction reaction (ORR) must first relate the formation of oxygen intermediates to basic electronic and electrostatic properties of the catalytic surface, and then link it to parameters of catalyst activity. An approach that accomplishes this feat will be of great utility for catalyst materials development and predictive model formulation of electrode operation. Here, we present a theoretical framework for the multiple interrelated surface phenomena and processes involved, particularly, by incorporating the double-layer effects. It sheds light on the roles of oxygen intermediates and gives out the Tafel slope and exchange current density as continuous functions of electrode potential. Moreover, it develops the concept of a rate determining term, which should replace the concept of a rate determining step for multielectron reactions, and offers a new perspective on the volcano relation of the ORR.

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

Y Cao; X Jin; H Huang

The TrkH/TrkG/KtrB proteins mediate K{sup +} uptake in bacteria and probably evolved from simple K{sup +} channels by multiple gene duplications or fusions. Here we present the crystal structure of a TrkH from Vibrio parahaemolyticus. TrkH is a homodimer, and each protomer contains an ion permeation pathway. A selectivity filter, similar in architecture to those of K{sup +} channels but significantly shorter, is lined by backbone and side-chain oxygen atoms. Functional studies showed that TrkH is selective for permeation of K{sup +} and Rb{sup +} over smaller ions such as Na{sup +} or Li{sup +}. Immediately intracellular to the selectivitymore » filter are an intramembrane loop and an arginine residue, both highly conserved, which constrict the permeation pathway. Substituting the arginine with an alanine significantly increases the rate of K{sup +} flux. These results reveal the molecular basis of K{sup +} selectivity and suggest a novel gating mechanism for this large and important family of membrane transport proteins.« less

Network reconstruction of platelet metabolism identifies metabolic signature for aspirin resistance

NASA Astrophysics Data System (ADS)

Thomas, Alex; Rahmanian, Sorena; Bordbar, Aarash; Palsson, Bernhard Ø.; Jamshidi, Neema

2014-01-01

Recently there has not been a systematic, objective assessment of the metabolic capabilities of the human platelet. A manually curated, functionally tested, and validated biochemical reaction network of platelet metabolism, iAT-PLT-636, was reconstructed using 33 proteomic datasets and 354 literature references. The network contains enzymes mapping to 403 diseases and 231 FDA approved drugs, alluding to an expansive scope of biochemical transformations that may affect or be affected by disease processes in multiple organ systems. The effect of aspirin (ASA) resistance on platelet metabolism was evaluated using constraint-based modeling, which revealed a redirection of glycolytic, fatty acid, and nucleotide metabolism reaction fluxes in order to accommodate eicosanoid synthesis and reactive oxygen species stress. These results were confirmed with independent proteomic data. The construction and availability of iAT-PLT-636 should stimulate further data-driven, systems analysis of platelet metabolism towards the understanding of pathophysiological conditions including, but not strictly limited to, coagulopathies.

2,3-Diphosphoglycerate: its role in health and disease.

PubMed

Juel, R

1979-01-01

2,3-Diphosphoglycerate (2,3-DPG) was first discovered and isolated in 1925. However, it was not until 1967 that the function of 2,3-DPG was explained. This resulted in multiple research projects devoted to elucidating the mechanism by which 2,3-DPG exerts it effect on the oxygen affinity of hemoglobin. In addition, a vast amount of research has been devoted to assessing the role of 2,3-DPG in oxygen transport in various physiological and pathophysiological states. In many instances, the results of this research have produced conflicting data which have dampened the initial enthusiasm which followed the discovery of the function of 2,3-DPG. However, much of this conflicting data can be explained by the fact that 2,3-DPG is only one of a number of factors influencing the transport of oxygen to the tissues. Several of these factors influence oxygen transport independently as well as by altering the synthesis of 2,3-DPG and modifying its effect on hemoglobin. In spite of the conflicting results, the overall data gathered thus far appears to be sound enough to warrant the extensive research now being done, particularly in the area of blood storage and transfusion therapy.

Biogeochemistry of a submerged groundwater seep ecosystem in Lake Huron near karst region of Alpena, MI

NASA Astrophysics Data System (ADS)

Kinsman-Costello, L. E.; Dick, G.; Sheik, C.; Burton, G. A.; Sheldon, N. D.

2015-12-01

Submerged groundwater seeps in Lake Huron establish ecosystems with distinctive geochemical conditions. In the Middle Island Sinkhole (MIS), a 23-m deep seep, groundwater seepage establishes low O2 (< 4 mg L-1), high sulfate (6 mM) conditions, in which a purple cyanobacteria-dominated mat thrives. The mat is capable of anoxygenic photosynthesis, oxygenic photosynthesis, and chemosynthesis. Within the top 3 cm of the mat-water interface, hydrogen sulfide concentrations increase to 1-7 mM. Little is known about the structure and function of microbes within organic-rich, high-sulfide sediments beneath the mat. Using pore water and sediment geochemical characterization along with microbial community analysis, we elucidated relationships between microbial community structure and ecosystem function along vertical gradients. In sediment pore waters, biologically reactive solutes (SO42-, NH4+, PO43-, and CH4) displayed steep vertical gradients, reflecting biological and geochemical functioning. In contrast, more conservative ions (Ca+2, Mg+2, Na+, and Cl-), did not change significantly with depth in MIS sediments, indicating groundwater influence in the sediment profile. MIS sediments contained more organic matter than typical Lake Huron sediments, and were generally higher in nutrients, metals, and sulfur (acid volatile sulfide). Using the Illumina MiSeq platform we detected 14,127 unique operational taxonomic units across sediment and surface mat samples. Microbial community composition in the MIS was distinctly different from non-groundwater affected areas at similar depth nearby in Lake Huron (ANOSIM, R= 0.74, p=0.002). MIS sediment communities were more diverse that MIS surface mat communities and changed with depth into sediments. MIS sediment community composition was related to several geochemical variables, including organic matter and multiple indicators of phosphorus availability. Elucidating the structure and function of microbial consortia in MIS, a highly unique and environmentally vulnerable ecosystem, provides a rare opportunity to understand relationships between microbial species and their environment and may provide insights into the evolution of life under ancient low-oxygen, high-sulfur conditions.

Importance of oxygen in the metal-free catalytic growth of single-walled carbon nanotubes from SiO(x) by a vapor-solid-solid mechanism.

PubMed

Liu, Bilu; Tang, Dai-Ming; Sun, Chenghua; Liu, Chang; Ren, Wencai; Li, Feng; Yu, Wan-Jing; Yin, Li-Chang; Zhang, Lili; Jiang, Chuanbin; Cheng, Hui-Ming

2011-01-19

To understand in-depth the nature of the catalyst and the growth mechanism of single-walled carbon nanotubes (SWCNTs) on a newly developed silica catalyst, we performed this combined experimental and theoretical study. In situ transmission electron microscopy (TEM) observations revealed that the active catalyst for the SWCNT growth is solid and amorphous SiO(x) nanoparticles (NPs), suggesting a vapor-solid-solid growth mechanism. From in situ TEM and chemical vapor deposition growth experiments, we found that oxygen plays a crucial role in SWCNT growth in addition to the well-known catalyst size effect. Density functional theory calculations showed that oxygen atoms can enhance the capture of -CH(x) and consequently facilitate the growth of SWCNTs on oxygen-containing SiO(x) NPs.

Conformation-dependent chemical reaction of formic acid with an oxygen atom.

PubMed

Khriachtchev, Leonid; Domanskaya, Alexandra; Marushkevich, Kseniya; Räsänen, Markku; Grigorenko, Bella; Ermilov, Alexander; Andrijchenko, Natalya; Nemukhin, Alexander

2009-07-23

Conformation dictates many physical and chemical properties of molecules. The importance of conformation in the selectivity and function of biologically active molecules is widely accepted. However, clear examples of conformation-dependent bimolecular chemical reactions are lacking. Here we consider a case of formic acid (HCOOH) that is a valuable model system containing the -COOH carboxyl functional group, similar to many biomolecules including the standard amino acids. We have found a strong case of conformation-dependent reaction between formic acid and atomic oxygen obtained in cryogenic matrices. The reaction surprisingly leads to peroxyformic acid only from the ground-state trans conformer of formic acid, and it results in the hydrogen-bonded complex for the higher-energy cis conformer.

Diamond surface functionalization with biomimicry - Amine surface tether and thiol moiety for electrochemical sensors

NASA Astrophysics Data System (ADS)

Sund, James B.; Causey, Corey P.; Wolter, Scott D.; Parker, Charles B.; Stoner, Brian R.; Toone, Eric J.; Glass, Jeffrey T.

2014-05-01

The surface of conducting diamond was functionalized with a terminal thiol group that is capable of binding and detecting nitrogen-oxygen species. The functionalization process employed multiple steps starting with doped diamond films grown by plasma enhanced chemical vapor deposition followed by hydrogen termination and photochemical attachment of a chemically protected amine alkene. The surface tether was deprotected to reveal the amine functionality, which enabled the tether to be extended with surface chemistry to add a terminal thiol moiety for electrochemical sensing applications. Each step of the process was validated using X-ray photoelectron spectroscopy analysis.

Linear and non-linear contributions to oxygen transport and utilization during moderate random exercise in humans.

PubMed

Beltrame, T; Hughson, R L

2017-05-01

What is the central question of this study? The pulmonary oxygen uptake (pV̇O2) data used to study the muscle aerobic system dynamics during moderate-exercise transitions is classically described as a mono-exponential function controlled by a complex interaction of the oxygen delivery-utilization balance. This elevated complexity complicates the acquisition of relevant information regarding aerobic system dynamics based on pV̇O2 data during a varying exercise stimulus. What is the main finding and its importance? The elevated complexity of pV̇O2 dynamics is a consequence of a multiple-order interaction between muscle oxygen uptake and circulatory distortion. Our findings challenge the use of a first-order function to study the influences of the oxygen delivery-utilization balance over the pV̇O2 dynamics. The assumption of aerobic system linearity implies that the pulmonary oxygen uptake (pV̇O2) dynamics during exercise transitions present a first-order characteristic. The main objective of this study was to test the linearity of the oxygen delivery-utilization balance during random moderate exercise. The cardiac output (Q̇) and deoxygenated haemoglobin concentration ([HHb]) were measured to infer the central and local O 2 availability, respectively. Thirteen healthy men performed two consecutive pseudorandom binary sequence cycling exercises followed by an incremental protocol. The system input and the outputs pV̇O2, [HHb] and Q̇ were submitted to frequency-domain analysis. The linearity of the variables was tested by computing the ability of the response at a specific frequency to predict the response at another frequency. The predictability levels were assessed by the coefficient of determination. In a first-order system, a participant who presents faster dynamics at a specific frequency should also present faster dynamics at any other frequency. All experimentally obtained variables (pV̇O2, [HHb] and Q̇) presented a certainly degree of non-linearity. The local O 2 availability, evaluated by the ratio pV̇O2/[HHb], presented the most irregular behaviour. The overall [HHb] kinetics were faster than pV̇O2 and Q̇ kinetics. In conclusion, the oxygen delivery-utilization balance behaved as a non-linear phenomenon. Therefore, the elevated complexity of the pulmonary oxygen uptake dynamics is governed by a complex multiple-order interaction between the oxygen delivery and utilization systems. © 2017 The Authors. Experimental Physiology © 2017 The Physiological Society.

Pyrolysis of polyethylene terephthalate containing real waste plastics using Ni loaded zeolite catalysts

NASA Astrophysics Data System (ADS)

Al-asadi, M.; Miskolczi, N.

2018-05-01

In this work the pyrolysis of polyethylene terephthalate (PET) containing real waste plastic was investigated using different Ni loaded catalysts: Ni/ZSM-5, Ni/y-zeolite, Ni/β-zeolite and Ni/natural zeolite (clinoptilolite). Raw materials were pyrolyzed in a horizontal tubular reactor between 600 and 900°C using 10% of catalysts. It was found, that both temperature increasing and catalysts presence can increase the gas yields, however owing to gasification reactions, the pyrolysis oil yield decreased with increasing temperature. Ni/y-zeolite catalyst had the most benefit in gas yield increasing at low temperature; however Ni/ZSM-5 showed advanced property in gas yield increasing at high temperature. Gases contained hydrogen, carbon oxides and hydrocarbons, which composition was significantly affected by catalysts. Ni loaded zeolites favoured to the formation of hydrogen and branched hydrocarbons; furthermore the concentrations of both CO and CO2 were also increased as function of elevated temperature. That phenomenon was attributed to the further decomposition of PET, especially to the side chain scission reactions. Owing to the Boudouard reaction, the ratio of CO2/CO can increased with temperature. Pyrolysis oils were the mixtures of n-saturated, n-unsaturated, branched, oxygen free aromatics and oxygenated hydrocarbons. Temperature increasing has a significant effect to the aromatization and isomerization reactions, while the catalysts can efficiently decreased the concentration of oxygen containing compounds.

77 FR 49386 - Airworthiness Directives; Airbus Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-16

... prompted by reports of silicon particles inside the oxygen generator manifolds, which had chafed from the... the part number and serial number of each passenger oxygen container, replacing the oxygen generator manifold of the affected oxygen container with a serviceable manifold, and performing an operational check...

Reactive oxygen species inactivate neuronal nicotinic acetylcholine receptors through a highly conserved cysteine near the intracellular mouth of the channel: implications for diseases that involve oxidative stress

PubMed Central

Krishnaswamy, Arjun; Cooper, Ellis

2012-01-01

Abstract An intriguing feature of several nicotinic acetylcholine receptors (nAChRs) on neurons is that their subunits contain a highly conserved cysteine residue located near the intracellular mouth of the receptor pore. The work summarized in this review indicates that α3β4-containing and α4β2-containing neuronal nAChRs, and possibly other subtypes, are inactivated by elevations in intracellular reactive oxygen species (ROS). This review discusses a model for the molecular mechanisms that underlie this inactivation. In addition, we explore the implications of this mechanism in the context of complications that arise from diabetes. We review the evidence that diabetes elevates cytosolic ROS in sympathetic neurons and inactivates postsynaptic α3β4-containing nAChRs shortly after the onset of diabetes, leading to a depression of synaptic transmission in sympathetic ganglia, an impairment of sympathetic reflexes. These effects of ROS on nAChR function are due to the highly conserved Cys residues in the receptors: replacing the cysteine residues in α3 allow ganglionic transmission and sympathetic reflexes to function normally in diabetes. This example from diabetes suggests that other diseases involving oxidative stress, such as Parkinson's disease, could lead to the inactivation of nAChRs on neurons and disrupt cholinergic nicotinic signalling. PMID:21969449

Creation of nanosized holes in graphene planes for improvement of rate capability of lithium-ion batteries

NASA Astrophysics Data System (ADS)

Bulusheva, L. G.; Stolyarova, S. G.; Chuvilin, A. L.; Shubin, Yu V.; Asanov, I. P.; Sorokin, A. M.; Mel'gunov, M. S.; Zhang, Su; Dong, Yue; Chen, Xiaohong; Song, Huaihe; Okotrub, A. V.

2018-04-01

Holes with an average size of 2-5 nm have been created in graphene layers by heating of graphite oxide (GO) in concentrated sulfuric acid followed by annealing in an argon flow. The hot mineral acid acts simultaneously as a defunctionalizing and etching agent, removing a part of oxygen-containing groups and lattice carbon atoms from the layers. Annealing of the holey reduced GO at 800 °C-1000 °C causes a decrease of the content of residual oxygen and the interlayer spacing thus producing thin compact stacks from holey graphene layers. Electrochemical tests of the obtained materials in half-cells showed that the removal of oxygen and creation of basal holes lowers the capacity loss in the first cycle and facilitates intercalation-deintercalation of lithium ions. This was attributed to minimization of electrolyte decomposition reactions, easier desolvation of lithium ions near the hole boundaries and appearance of multiple entrances for the naked ions into graphene stacks.

The Cys-Arg/N-End Rule Pathway Is a General Sensor of Abiotic Stress in Flowering Plants.

PubMed

Vicente, Jorge; Mendiondo, Guillermina M; Movahedi, Mahsa; Peirats-Llobet, Marta; Juan, Yu-Ting; Shen, Yu-Yen; Dambire, Charlene; Smart, Katherine; Rodriguez, Pedro L; Charng, Yee-Yung; Gray, Julie E; Holdsworth, Michael J

2017-10-23

Abiotic stresses impact negatively on plant growth, profoundly affecting yield and quality of crops. Although much is known about plant responses, very little is understood at the molecular level about the initial sensing of environmental stress. In plants, hypoxia (low oxygen, which occurs during flooding) is directly sensed by the Cys-Arg/N-end rule pathway of ubiquitin-mediated proteolysis, through oxygen-dependent degradation of group VII Ethylene Response Factor transcription factors (ERFVIIs) via amino-terminal (Nt-) cysteine [1, 2]. Using Arabidopsis (Arabidopsis thaliana) and barley (Hordeum vulgare), we show that the pathway regulates plant responses to multiple abiotic stresses. In Arabidopsis, genetic analyses revealed that response to these stresses is controlled by N-end rule regulation of ERFVII function. Oxygen sensing via the Cys-Arg/N-end rule in higher eukaryotes is linked through a single mechanism to nitric oxide (NO) sensing [3, 4]. In plants, the major mechanism of NO synthesis is via NITRATE REDUCTASE (NR), an enzyme of nitrogen assimilation [5]. Here, we identify a negative relationship between NR activity and NO levels and stabilization of an artificial Nt-Cys substrate and ERFVII function in response to environmental changes. Furthermore, we show that ERFVIIs enhance abiotic stress responses via physical and genetic interactions with the chromatin-remodeling ATPase BRAHMA. We propose that plants sense multiple abiotic stresses through the Cys-Arg/N-end rule pathway either directly (via oxygen sensing) or indirectly (via NO sensing downstream of NR activity). This single mechanism can therefore integrate environment and response to enhance plant survival. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

78 FR 40074 - Airworthiness Directives; Airbus Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-03

... certain batch of passenger emergency oxygen container assemblies might become detached by extreme pulling of the mask tube at the end of oxygen supply causing a high temperature oxygen generator and mask to fall down. This proposed AD would require modifying the passenger emergency oxygen container assembly...

Effect of oxygen supply on the size of implantable islet-containing encapsulation devices.

PubMed

Papas, Klearchos K; Avgoustiniatos, Efstathios S; Suszynski, Thomas M

2016-03-01

Beta-cell replacement therapy is a promising approach for the treatment of diabetes but is currently limited by the human islet availability and by the need for systemic immunosuppression. Tissue engineering approaches that will enable the utilization of islets or β-cells from alternative sources (such as porcine islets or human stem cell derived beta cells) and minimize or eliminate the need for immunosuppression have the potential to address these critical limitations. However, tissue engineering approaches are critically hindered by the device size (similar to the size of a large flat screen television) required for efficacy in humans. The primary factor dictating the device size is the oxygen availability to islets to support their viability and function (glucose-stimulated insulin secretion [GSIS]). GSIS is affected (inhibited) at a much higher oxygen partial pressure [pO2] than that of viability (e.g. 10 mmHg as opposed to 0.1 mmHg). Enhanced oxygen supply (higher pO2) than what is available in vivo at transplant sites can have a profound effect on the required device size (potentially reduce it to the size of a postage stamp). This paper summarizes key information on the effect of oxygen on islet viability and function within immunoisolation devices and describes the potential impact of enhanced oxygen supply to devices in vivo on device size reduction.

Solid state oxygen sensor

DOEpatents

Garzon, Fernando H.; Chung, Brandon W.; Raistrick, Ian D.; Brosha, Eric L.

1996-01-01

Solid state oxygen sensors are provided with a yttria-doped zirconia as an electrolyte and use the electrochemical oxygen pumping of the zirconia electrolyte. A linear relationship between oxygen concentration and the voltage arising at a current plateau occurs when oxygen accessing the electrolyte is limited by a diffusion barrier. A diffusion barrier is formed herein with a mixed electronic and oxygen ion-conducting membrane of lanthanum-containing perovskite or zirconia-containing fluorite. A heater may be used to maintain an adequate oxygen diffusion coefficient in the mixed conducting layer.

78 FR 64162 - Airworthiness Directives; Airbus Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-28

... container assembly. We are issuing this AD to prevent a high temperature oxygen generator and mask from... oxygen generators installed on a certain batch of passenger emergency oxygen container assemblies might become detached by extreme pulling of the mask tube at the end of the oxygen supply causing a high...

Strong coupling diagram technique for the three-band Hubbard model

NASA Astrophysics Data System (ADS)

Sherman, A.

2016-03-01

Strong coupling diagram technique equations are derived for hole Green’s functions of the three-band Hubbard model, which describes Cu-O planes of high-Tc cuprates. The equations are self-consistently solved in the approximation, in which the series for the irreducible part in powers of the oxygen-copper hopping constant is truncated to two lowest-order terms. For parameters used for hole-doped cuprates, the calculated energy spectrum consists of lower and upper Hubbard subbands of predominantly copper nature, oxygen bands with a small admixture of copper states and the Zhang-Rice states of mixed nature, which are located between the lower Hubbard subband and oxygen bands. The spectrum contains also pseudogaps near transition frequencies of Hubbard atoms on copper sites.

The Mn4Ca-cluster of the photosynthetic oxygen evolving centre: its structure, function and evolution.

PubMed

Barber, James

2016-10-05

Photosystem II is the chlorophyll containing enzyme in which the very first chemical energy storing reaction of photosynthesis occurs. It does so by splitting water into molecular oxygen and hydrogen equivalents at a catalytic centre composed of four Mn ions and one Ca2+. All the oxygen in the atmosphere is derived from this reaction and without it the biosphere, as we know it, would not exist. Indeed its appearance about 3 billion years ago gave rise to the "big bang of evolution". Thus understanding the structure and functioning of this metal cluster is a major topic in science and here I discuss it in terms of research over of the last twelve years dating back to when it was first proposed to be a Mn3CaO4 cubane with the fourth Mn attached to cubane by one of its oxo bridging bonds. In so doing a number of novel properties emerge for this metallo-protein with implications for its mechanism and evolutionary origin.

Directional liquefaction of biomass for phenolic compounds and in situ hydrodeoxygenation upgrading of phenolics using bifunctional catalysts

Treesearch

Junfeng Feng; Chung-yun Hse; Kui Wang; Zhongzhi Yang; Jianchun Jiang; Junming Xu

2017-01-01

Phenolic compounds derived from biomass are important feedstocks for the sustainable production of hydrocarbon biofuels. Hydrodeoxygenation is an effective process to remove oxygen-containing functionalities in phenolic compounds. This paper reported a simple method for producing hydrocarbons by liquefying biomass and upgrading liquefied products. Three phenolic...

Direct growth of high crystallinity graphene from water-soluble polymer powders

NASA Astrophysics Data System (ADS)

Chen, Qiao; Zhong, Yujia; Huang, Meirong; Zhao, Guoke; Zhen, Zhen; Zhu, Hongwei

2018-07-01

The use of solid-state carbon sources is effective to produce graphene by safe and low-cost chemical vapor deposition (CVD) process. Water-soluble polymers are generally environmentally friendly and have great potential on large-scale green production of graphene. Here, we systematically study the growth of graphene from water-soluble polymers on copper foils. Two different conversion ways are adopted to investigate the growth mechanism of graphene from water-soluble polymers. We find that the metal-binding functional group hydroxyl strongly influences the vaporization of water-soluble polymers on Cu foils, which hinders the formation of graphene films by rapid thermal treatment. In direct CVD process using water-soluble polymer powders as precursors, oxygenated functional groups in polymers can enhance the crystallinity of as-grown graphene in contrast to solid hydrocarbons without containing oxygen (e.g. polyethylene). Large and continuous graphene films of high quality are synthesized from polyvinyl alcohol and polyethylene glycol. Nitrogen doping in graphene can be easily realized by using nitrogen-containing water-soluble polymers (e.g. polyvinyl pyrrolidone).

Biochar production method and composition therefrom

DOEpatents

Lee, James W; Buchanan, III, Archibald C; Evans, Barbara R; Kidder, Michelle K

2014-04-29

The invention is directed to a method for producing an oxygenated biochar material possessing a cation-exchanging property, wherein a biochar source is reacted with one or more oxygenating compounds in such a manner that the biochar source homogeneously acquires oxygen-containing cation-exchanging groups in an incomplete combustion process. The invention is also directed to oxygenated biochar compositions and soil formulations containing the oxygenated biochar material.

Biochar production method and composition therefrom

DOEpatents

Lee, James W.; Buchanan, III, Archibald C.; Evans, Barbara R.; Kidder, Michelle K.

2013-03-19

The invention is directed to a method for producing an oxygenated biochar material possessing a cation-exchanging property, wherein a biochar source is reacted with one or more oxygenating compounds in such a manner that the biochar source homogeneously acquires oxygen-containing cation-exchanging groups in an incomplete combustion process. The invention is also directed to oxygenated biochar compositions and soil formulations containing the oxygenated biochar material.

Stiffness and strength of oxygen-functionalized graphene with vacancies

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

Zandiatashbar, A.; Ban, E.; Picu, R. C., E-mail: picuc@rpi.edu

2014-11-14

The 2D elastic modulus (E{sup 2D}) and strength (σ{sup 2D}) of defective graphene sheets containing vacancies, epoxide, and hydroxyl functional groups are evaluated at 300 K by atomistic simulations. The fraction of vacancies is controlled in the range 0% to 5%, while the density of functional groups corresponds to O:C ratios in the range 0% to 25%. In-plane modulus and strength diagrams as functions of vacancy and functional group densities are generated using models with a single type of defect and with combinations of two types of defects (vacancies and functional groups). It is observed that in models containing only vacancies,more » the rate at which strength decreases with increasing the concentration of defects is largest, followed by models containing only epoxide groups and those with only hydroxyl groups. The effect on modulus of vacancies and epoxides present alone in the model is similar, and much stronger than that of hydroxyl groups. When the concentration of defects is large, the combined effect of the functional groups and vacancies cannot be obtained as the superposition of individual effects of the two types of defects. The elastic modulus deteriorates faster (slower) than predicted by superposition in systems containing vacancies and hydroxyl groups (vacancies and epoxide groups)« less

Novel Functions of an Iron-Sulfur Flavoprotein from Trichomonas vaginalis Hydrogenosomes

PubMed Central

Smutná, Tamara; Pilarová, Katerina; Tarábek, Ján; Tachezy, Jan

2014-01-01

Iron-sulfur flavoproteins (Isf) are flavin mononucleotide (FMN)- and FeS cluster-containing proteins commonly encountered in anaerobic prokaryotes. However, with the exception of Isf from Methanosarcina thermophila, which participates in oxidative stress management by removing oxygen and hydrogen peroxide, none of these proteins has been characterized in terms of function. Trichomonas vaginalis, a sexually transmitted eukaryotic parasite of humans, was found to express several iron-sulfur flavoprotein (TvIsf) homologs in its hydrogenosomes. We show here that in addition to having oxygen-reducing activity, the recombinant TvIsf also functions as a detoxifying reductase of metronidazole and chloramphenicol, both of which are antibiotics effective against a variety of anaerobic microbes. TvIsf can utilize both NADH and reduced ferredoxin as electron donors. Given the prevalence of Isf in anaerobic prokaryotes, we propose that these proteins are central to a novel defense mechanism against xenobiotics. PMID:24663020

**1**5N-NMR INVESTIGATION OF HYDROXYLAMINE DERIVATIZED HUMIC SUBSTANCES.

USGS Publications Warehouse

Thorn, Kevin A.; Arterburn, Jeffrey B.; Mikita, Michael A.

1986-01-01

Humic substances are the most abundant naturally occurring refactory organic compounds in soils and water. They have a broad range of physical, chemical and physiological properties. In soils, humic substances contribute to the cation exchange capacity, help maintain the physical structure, and play a role in plant growth and nutrition. In aquatic systems, humic substances serve to regulate the levels of inorganic constituents, yield trihalomethanes upon chlorination, and transport or concentrate organic and inorganic pollutants. The oxygen containing functional groups of humic and fulvic acids are believed to play a key role in the chemical properties of humic substances. This study was undertaken to gain additional information on the specific types of oxygen functionalities in humic substances. Since the analysis of hydroxyl moieties had been earlier established, we focused our attention on the analysis of ketone and aldehyde functional groups in humic substances.

Carefully designed oxygen-containing functional groups and defects of porous carbon spheres with UV-O3 treatment and their enhanced catalytic performance

NASA Astrophysics Data System (ADS)

Han, Weiliang; Huang, Xiaosheng; Lu, Gongxuan; Tang, Zhicheng

2018-04-01

In this paper, the support surface properties (surface oxygen-containing functional groups and structure defects) of porous carbon spheres (PCSs) were carefully designed by as UV assisted O3 technology. CO catalytic oxidation reactions performed over the supported Pd-Ce catalysts on modified porous carbon spheres. Results illustrated that the Pd-Ce/PCSs catalysts exhibited high CO catalytic activity, which were increased at first, and then decreased with UV assistant-O3 treatment time. The Pd-Ce/PCSs-30 catalyst exhibited superior activity and T100 was only 15 °C. Moreover, the Pd-Ce/PCSs-30 catalyst obtained an excellent stability, and 100% CO conversion could be maintained as the time on stream evolutes up to 16h in the presence of H2O in the feed. Based on characterization results, there were two main factors: (a) the surface area and pore volume were decreased with UV-O3 treatment, leading to the enhancement of Pd-Ce particle size, and the decrease of Pd-Ce nanoparticle dispersion and mass transfer efficiency, as well as the decrease of catalytic activity of Pd-Ce/PCSs, (b) the surface oxygen content and defect sites of PCSs were raised by UV-O3 treatment, which could improve surface loading of Pd, Ce and enhance Pdsbnd Osbnd Ce bonding interactions, thereby increasing the activity of Pd-Ce/PCSs.

Asymmetric 3d Electronic Structure for Enhanced Oxygen Evolution Catalysis.

PubMed

Liu, Yang; Yin, Shibin; Shen, Pei Kang

2018-06-27

The oxygen evolution reaction (OER) is an essential process for renewable energy, and designing a bifunctional oxygen electrocatalyst with high catalytic performance plays a significant role. In this work, FeS, Ni 3 S 2 , Fe 5 Ni 4 S 8 , and N, O, S-doped meshy carbon base were successfully synthesized. The sample containing Fe 5 Ni 4 S 8 exhibited excellent OER performance. The density functional theory calculations indicate that the partial density of states for 3d electrons (3d-PDOS) of Fe and Ni atoms are changed from monometallic sulfide to bimetallic sulfide at the sulfur vacancy. The asymmetric 3d electronic structure optimizes the 3d-PDOS of Fe and Ni atoms, and leads to an enhanced OER activity. This work provides a new strategy to prepare a low-cost electrocatalyst for oxygen evolution with high-efficiency.

Surface energy modification for biomedical material by corona streamer plasma processing to mitigate bacterial adhesion

NASA Astrophysics Data System (ADS)

Alhamarneh, Ibrahim; Pedrow, Patrick

2011-10-01

Bacterial adhesion initiates biofouling of biomedical material but the processes can be reduced by adjusting the material's surface energy. The surface of surgical-grade 316L stainless steel (316L SS) had its hydrophilic property enhanced by processing in a corona streamer plasma reactor using atmospheric pressure Ar mixed with O2. Reactor excitation was 60 Hz ac high-voltage (<= 10 kV RMS) applied to a multi-needle-to-grounded-torus electrode configuration. Applied voltage and streamer current pulses were monitored with a broadband sensor system. When Ar/O2 plasma was used, the surface energy was enhanced more than with Ar plasma alone. Composition of the surface before and after plasma treatment was characterized by XPS. As the hydrophilicity of the treated surface increased so did percent of oxygen on the surface thus we concluded that reduction in contact angle was mainly due to new oxygen-containing functionalities. FTIR was used to identify oxygen containing groups on the surface. The aging effect that accompanies surface free energy adjustments was also observed.

Efficient epoxidation of a terminal alkene containing allylic hydrogen atoms: trans-methylstyrene on Cu{111}.

PubMed

Cropley, Rachael L; Williams, Federico J; Urquhart, Andrew J; Vaughan, Owain P H; Tikhov, Mintcho S; Lambert, Richard M

2005-04-27

The selective oxidation of trans-methylstyrene, a phenyl-substituted propene that contains labile allylic hydrogen atoms, has been studied on Cu{111}. Mass spectrometry and synchrotron fast XPS were used to detect, respectively, desorbing gaseous products and the evolution of surface species as a function of temperature and time. Efficient partial oxidation occurs yielding principally the epoxide, and the behavior of the system is sensitive to the order in which reactants are adsorbed. The latter is understandable in terms of differences in the spatial distribution of oxygen adatoms; isolated adatoms lead to epoxidation, while islands of "oxidic" oxygen do not. NEXAFS data taken over a range of coverages and in the presence and absence of coadsorbed oxygen indicate that the adsorbed alkene lies essentially flat with the allylic hydrogen atoms close to the surface. The photoemission results and comparison with the corresponding behavior of styrene on Cu{111} strongly suggest that allylic hydrogen abstraction is indeed a critical factor that limits epoxidation selectivity. An overall mechanism consistent with the structural and reactive properties is proposed.

Solid state oxygen sensor

DOEpatents

Garzon, F.H.; Chung, B.W.; Raistrick, I.D.; Brosha, E.L.

1996-08-06

Solid state oxygen sensors are provided with a yttria-doped zirconia as an electrolyte and use the electrochemical oxygen pumping of the zirconia electrolyte. A linear relationship between oxygen concentration and the voltage arising at a current plateau occurs when oxygen accessing the electrolyte is limited by a diffusion barrier. A diffusion barrier is formed herein with a mixed electronic and oxygen ion-conducting membrane of lanthanum-containing perovskite or zirconia-containing fluorite. A heater may be used to maintain an adequate oxygen diffusion coefficient in the mixed conducting layer. 4 figs.

Purification, crystallization and preliminary crystallographic studies of haemoglobin from mongoose (Helogale parvula) in two different crystal forms induced by pH variation

PubMed Central

Mohamed Abubakkar, M.; Saraboji, K.; Ponnuswamy, M. N.

2013-01-01

Haemoglobin (Hb) is a respiratory pigment; it is a tetrameric protein that ferries oxygen from the lungs to tissues and transports carbon dioxide on the return journey. The oxygen affinity of haemoglobin is regulated by the concentration of oxygen surrounding it and several efforts have revealed the shapes of Hb in different states and with different functions. However, study of the molecular basis of Hbs from low-oxygen-affinity species is critically needed in order to increase the understanding of the mechanism behind oxygen adaptation. The present study reports the preliminary crystallographic study of low-oxygen-affinity haemoglobin from mongoose, a burrowing mammal. Haemoglobin from mongoose was purified by anion-exchange chromatography, crystallized using the hanging-drop vapour-diffusion method and diffraction data sets were collected from monoclinic (2.3 Å resolution) and orthorhombic (2.9 Å resolution) crystal forms obtained by pH variation. The monoclinic and orthorhombic asymmetric units contained half and a whole biological molecule, respectively. PMID:23385751

Validation of oxygen extraction fraction measurement by qBOLD technique.

PubMed

He, Xiang; Zhu, Mingming; Yablonskiy, Dmitriy A

2008-10-01

Measurement of brain tissue oxygen extraction fraction (OEF) in both baseline and functionally activated states can provide important information on brain functioning in health and disease. The recently proposed quantitative BOLD (qBOLD) technique is MRI-based and provides a regional in vivo OEF measurement (He and Yablonskiy, MRM 2007, 57:115-126). It is based on a previously developed analytical BOLD model and incorporates prior knowledge about the brain tissue composition including the contributions from grey matter, white matter, cerebrospinal fluid, interstitial fluid and intravascular blood. The qBOLD model also allows for the separation of contributions to the BOLD signal from OEF and the deoxyhemoglobin containing blood volume (DBV). The objective of this study is to validate OEF measurements provided by the qBOLD approach. To this end we use a rat model and compare qBOLD OEF measurements against direct measurements of the blood oxygenation level obtained from venous blood drawn directly from the superior sagittal sinus. The cerebral venous oxygenation level of the rat was manipulated by utilizing different anestheisa methods. The study demonstrates a very good agreement between qBOLD approach and direct measurements. (c) 2008 Wiley-Liss, Inc.

Graphene oxide papers with high water adsorption capacity for air dehumidification.

PubMed

Liu, Renlong; Gong, Tao; Zhang, Kan; Lee, Changgu

2017-08-29

Graphene oxide (GO) has shown a high potential to adsorb and store water molecules due to the oxygen-containing functional groups on its hydrophilic surface. In this study, we characterized the water absorbing properties of graphene oxide in the form of papers. We fabricated three kinds of graphene oxide papers, two with rich oxygen functional groups and one with partial chemical reduction, to vary the oxygen/carbon ratio and found that the paper with high oxygen content has higher moisture adsorption capability. For the GO paper with reduction, the overall moisture absorbance was reduced. However, the absorbance at high humidity was significantly improved due to direct formation of multilayer water vapor in the system, which derived from the weak interaction between the adsorbent and the adsorbate. To demonstrate one application of GO papers as a desiccant, we tested grape fruits with and without GO paper. The fruits with a GO paper exhibited longer-term preservation with delayed mold gathering because of desiccation effect from the paper. Our results suggest that GO will find numerous practical applications as a desiccant and is a promising material for moisture desiccation and food preservation.

Moisture transport across Canada: evidence from stable oxygen and deuterium isotope values of lakes and rivers

NASA Astrophysics Data System (ADS)

Oakley, J. R.; Patterson, W. P.

2008-12-01

Global warming models often contain a prediction of changes in precipitation, yet modern moisture cycling is poorly understood. Stable oxygen and deuterium isotope values of several thousand lake and river water samples collected from 2004 to 2008 throughout Canada and the Northern United States provide a means to evaluate variations in the movement of moisture across the northern North American continent. Our particular focus is on the moisture tracking in the province of Saskatchewan. The dominant moisture source for Saskatchewan is the Gulf of Mexico, though precipitation contains some water from the Pacific and Arctic Oceans as well. By sampling locations multiple times, we established time series of isotope variability that we can relate to meteorological variation. A series of cross-plots of oxygen to deuterium isotopes for each year exhibits an increase in slope from year to year that reflects an increase in humidity and/or precipitation throughout the Prairies from 2004 to 2008. We define the influence of temperature, precipitation and humidity on the change in slope for each suite of samples. Ultimately, by combining our evidence of moisture transport with a grid of long-term secular records from lakes, speleothems and tree-ring isotope variability, we can not only reconstruct changes in atmospheric circulation through time, but also better predict what will happen in the future under various global climate change scenarios.

Oxygen transport membrane system and method for transferring heat to catalytic/process reactors

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

Kelly, Sean M.; Kromer, Brian R.; Litwin, Michael M.

A method and apparatus for producing heat used in a synthesis gas production process is provided. The disclosed method and apparatus include a plurality of tubular oxygen transport membrane elements adapted to separate oxygen from an oxygen containing stream contacting the retentate side of the membrane elements. The permeated oxygen is combusted with a hydrogen containing synthesis gas stream contacting the permeate side of the tubular oxygen transport membrane elements thereby generating a reaction product stream and radiant heat. The present method and apparatus also includes at least one catalytic reactor containing a catalyst to promote the steam reforming reactionmore » wherein the catalytic reactor is surrounded by the plurality of tubular oxygen transport membrane elements. The view factor between the catalytic reactor and the plurality of tubular oxygen transport membrane elements radiating heat to the catalytic reactor is greater than or equal to 0.5« less

Oxygen transport membrane system and method for transferring heat to catalytic/process reactors

DOEpatents

Kelly, Sean M; Kromer, Brian R; Litwin, Michael M; Rosen, Lee J; Christie, Gervase Maxwell; Wilson, Jamie R; Kosowski, Lawrence W; Robinson, Charles

2014-01-07

A method and apparatus for producing heat used in a synthesis gas production is provided. The disclosed method and apparatus include a plurality of tubular oxygen transport membrane elements adapted to separate oxygen from an oxygen containing stream contacting the retentate side of the membrane elements. The permeated oxygen is combusted with a hydrogen containing synthesis gas stream contacting the permeate side of the tubular oxygen transport membrane elements thereby generating a reaction product stream and radiant heat. The present method and apparatus also includes at least one catalytic reactor containing a catalyst to promote the stream reforming reaction wherein the catalytic reactor is surrounded by the plurality of tubular oxygen transport membrane elements. The view factor between the catalytic reactor and the plurality of tubular oxygen transport membrane elements radiating heat to the catalytic reactor is greater than or equal to 0.5.

Rate My Sleep: Examining the Information, Function, and Basis in Empirical Evidence Within Sleep Applications for Mobile Devices.

PubMed

Lee-Tobin, Peta A; Ogeil, Rowan P; Savic, Michael; Lubman, Dan I

2017-11-15

Sleep applications (apps) have proliferated in online spaces, but few studies have examined the validity of the information contained within the apps. This study aimed to examine the information and functions found within sleep apps, determine if the information is based on empirical evidence, and whether or not user ratings were affected by these factors. Sleep apps found in the Google Play store (n = 76) were coded using content analysis to examine the types of information, functions, and evidence base of each app. Only 32.9% of sleep apps contained empirical evidence supporting their claims, 15.8% contained clinical input, and 13.2% contained links to sleep literature. Apps also contained information on how sleep is affected by alcohol or drugs (23.7%), food (13.2%), daily activities (13.2), and stress (13.2%). A mean difference in average user rating was found between apps that contained at least one source of information compared those that did not. App user ratings were not associated with an app having multiple functions, or from an app drawing on multiple sources of evidence (except for sleep literature only). Last, there was a higher average user rating among apps that contained a sleep tip function. Sleep apps are increasingly popular, demonstrated by the large number of downloads in the Google Play store. Users favored apps that contained sleep tips; however, these tips and other information in the apps were generally not based on empirical evidence. Future research in the area of sleep apps should consider constructing sleep apps derived from empirical evidence and examining their effectiveness. © 2017 American Academy of Sleep Medicine

Improved extension of platelet storage in a polyolefin container with higher oxygen permeability.

PubMed

Yuasa, Takeshi; Ohto, Hitoshi; Yasunaga, Reiko; Kai, Takanori; Shirahama, Noriaki; Ogata, Takashi

2004-07-01

This study evaluated a newly developed polyolefin bag, which has a 50%/m(2) higher oxygen permeability to extend the shelf-life of platelets. Single-donor aphaeresis platelets were pooled, separated equally into two bags, PO-80 (0.8 l capacity) and KBP-PO (1 l capacity) for control, and stored in plasma for up to 7 d. Platelet biochemical and functional parameters were monitored in bags containing high (4.2 x 10(11)/250 ml/bag, n = 9) and low (2.0 x 10(11)/200 ml/bag, n = 3) concentrations of platelets over the storage period. After 7 d of storage, the PO-80 bags containing high concentrations of platelets had a better pH (mean pH 6.74) than those stored in KBP-PO (pH 6.32, P < 0.01); none of the nine PO-80 bags with a high platelet concentration had a pH below 6.2, compared with four of nine controls (P < 0.05). Similarly, lactate values were 20.19 mmol/l and 28.09 mmol/l respectively (P < 0.05). Aerobic metabolism was maintained better with greater O(2) consumption and less lactate generation in high-platelet concentration PO-80 bags than in the control bags. A significant difference was also found in pH, pCO(2) and lactate levels between the two bags containing low concentrations of platelets during the 7-d period. The in vitro characteristics of platelets declined less over 7 d when stored in a higher oxygen permeable container than in a marketed bag.

Oxygen sensitivity of mitochondrial function in rat arterial chemoreceptor cells

PubMed Central

Buckler, Keith J; Turner, Philip J

2013-01-01

The mechanism of oxygen sensing in arterial chemoreceptors is unknown but has often been linked to mitochondrial function. A common criticism of this hypothesis is that mitochondrial function is insensitive to physiological levels of hypoxia. Here we investigate the effects of hypoxia (down to 0.5% O2) on mitochondrial function in neonatal rat type-1 cells. The oxygen sensitivity of mitochondrial [NADH] was assessed by monitoring autofluorescence and increased in hypoxia with a P50 of 15 mm Hg (1 mm Hg = 133.3 Pa) in normal Tyrode or 46 mm Hg in Ca2+-free Tyrode. Hypoxia also depolarised mitochondrial membrane potential (ψm, measured using rhodamine 123) with a P50 of 3.1, 3.3 and 2.8 mm Hg in normal Tyrode, Ca2+-free Tyrode and Tyrode containing the Ca2+ channel antagonist Ni2+, respectively. In the presence of oligomycin and low carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP; 75 nm) ψm is maintained by electron transport working against an artificial proton leak. Under these conditions hypoxia depolarised ψm/inhibited electron transport with a P50 of 5.4 mm Hg. The effects of hypoxia upon cytochrome oxidase activity were investigated using rotenone, myxothiazol, antimycin A, oligomycin, ascorbate and the electron donor tetramethyl-p-phenylenediamine. Under these conditions ψm is maintained by complex IV activity alone. Hypoxia inhibited cytochrome oxidase activity (depolarised ψm) with a P50 of 2.6 mm Hg. In contrast hypoxia had little or no effect upon NADH (P50= 0.3 mm Hg), electron transport or cytochrome oxidase activity in sympathetic neurons. In summary, type-1 cell mitochondria display extraordinary oxygen sensitivity commensurate with a role in oxygen sensing. The reasons for this highly unusual behaviour are as yet unexplained. PMID:23671162

Electrochemical Characterization of O2 Plasma Functionalized Multi-Walled Carbon Nanotube Electrode for Legionella pneumophila DNA Sensor

NASA Astrophysics Data System (ADS)

Park, Eun Jin; Lee, Jun-Yong; Hyup Kim, Jun; Kug Kim, Sun; Lee, Cheol Jin; Min, Nam Ki

2010-08-01

An electrochemical DNA sensor for Legionella pneumophila detection was constructed using O2 plasma functionalized multi-walled carbon nanotube (MWCNT) film as a working electrode (WE). The cyclic voltammetry (CV) results revealed that the electrocatalytic activity of plasma functionalized MWCNT (pf-MWCNT) significantly changed depending on O2 plasma treatment time due to some oxygen containing functional groups on the pf-MWCNT surface. Scanning electron microscope (SEM) images and X-ray photoelectron spectroscopy (XPS) spectra were also presented the changes of their surface morphologies and oxygen composition before and after plasma treatment. From a comparison study, it was found that the pf-MWCNT WEs had higher electrocatalytic activity and more capability of probe DNA immobilization: therefore, electrochemical signal changes by probe DNA immobilization and hybridization on pf-MWCNT WEs were larger than on Au WEs. The pf-MWCNT based DNA sensor was able to detect a concentration range of 10 pM-100 nM of target DNA to detect L. pneumophila.

Structure and function of nematode communities across the Indian western continental margin and its oxygen minimum zone

NASA Astrophysics Data System (ADS)

Singh, R.; Ingole, B. S.

2016-01-01

We studied patterns of nematode distribution along the western Indian continental margin to determine the influence of habitat heterogeneity and low oxygen levels on the community's taxonomic and functional structure. A single transect, perpendicular to the coast at 14° N latitude was sampled from 34 to 2546 m depth for biological and environmental variables during August 2007. The oxygen minimum zone extended from 102 to 1001 m. Nematodes (described and undescribed) were identified to species and classified according to biological and functional traits. A total of 110 nematode species belonging to 24 families were found along the transect. Three depth zones were identified: the shelf (depth range: 34-102 m; highest nematode mean density: 176.6 ± 37 ind 10 cm-2), the slope (525-1524 m; 124.3 ± 16 ind 10 cm-2), and the basin (2001-2546 m; 62.9 ± 2 ind 10 cm-2). Across the entire study area, the dominant species were Terschellingia longicaudata, Desmodora sp. 1, Sphaerolaimus gracilis, and Theristus ensifer; their maximum density was at shelf stations. Nematode communities in different zones differed in species composition. Chromadorita sp. 2 (2.78 %) and Sphaerolaimus gracilis (2.21 %) were dominant on the shelf, whereas Terschellingia longicaudata (4.73 %) and Desmodora sp. 1 (4.42 %) were dominant on the slope, but in the basin, Halalaimus sp. 1(1.11 %) and Acantholaimus elegans (1.11 %) were dominant. The information in a particular functional group was not a simple reflection of the information in species abundance. Ecological information captured by adult length, adult shape, and life-history strategy was less site-specific and thus differed notably from information contained in other taxonomic groups. The functional composition of nematodes was strongly linked to the organic-carbon and dissolved-oxygen concentration. Seven species were found exclusively in the oxygen minimum zone: Pselionema sp. 1, Choanolaimus sp. 2, Halichoanolaimus sp. 1, Cobbia dentata, Daptonema sp. 1, Trissonchulus sp. 1, and Minolaimus sp. 1. Correlation with a number of environmental variables indicated that food quantity (measured as the organic-carbon content and chlorophyll content) and oxygen level were the major factors that influenced nematode community structure and function.

Method and reaction pathway for selectively oxidizing organic compounds

DOEpatents

Camaioni, Donald M.; Lilga, Michael A.

1998-01-01

A method of selectively oxidizing an organic compound in a single vessel comprises: a) combining an organic compound, an acid solution in which the organic compound is soluble, a compound containing two oxygen atoms bonded to one another, and a metal ion reducing agent capable of reducing one of such oxygen atoms, and thereby forming a mixture; b) reducing the compound containing the two oxygen atoms by reducing one of such oxygen atoms with the metal ion reducing agent to, 1) oxidize the metal ion reducing agent to a higher valence state, and 2) produce an oxygen containing intermediate capable of oxidizing the organic compound; c) reacting the oxygen containing intermediate with the organic compound to oxidize the organic compound into an oxidized organic intermediate, the oxidized organic intermediate having an oxidized carbon atom; d) reacting the oxidized organic intermediate with the acid counter ion and higher valence state metal ion to bond the acid counter ion to the oxidized carbon atom and thereby produce a quantity of an ester incorporating the organic intermediate and acid counter ion; and e) reacting the oxidized organic intermediate with the higher valence state metal ion and water to produce a quantity of alcohol which is less than the quantity of ester, the acid counter ion incorporated in the ester rendering the carbon atom bonded to the counter ion less reactive with the oxygen containing intermediate in the mixture than is the alcohol with the oxygen containing intermediate.

Oxygen permeability of the pigmented material used in cosmetic daily disposable contact lenses.

PubMed

Galas, Stephen; Copper, Lenora L

2016-01-01

To evaluate the individual contributions of pigment colorant and packing solution containing polyvinyl pyrrolidone (PVP) on the oxygen permeability (Dk) of a cosmetic printed etafilcon A daily disposable contact lens packaged with PVP. The oxygen transport of a contact lens is evaluated through the central optical zone of the lens. Cosmetic printed contact lenses contain pigment colorant in the periphery or mid-periphery of the lens. Therefore, to assess the impact of cosmetic print on oxygen permeability, special lenses need to be produced that contain the colorant within the central optical zone. This technique was used to obtain multiple measurements of nonedge-corrected Dk/t of both the center pigmented lens and its nonpigmented equivalent, using a polarographic measurement described in International Organization for Standardization (ISO) 18369-4:2006(E), and the Dk derived for each measurement is corrected for edge effect. In addition, the edge-corrected Dk values of lenses made from the same monomer batch were measured. The lenses were packaged and autoclaved with and without proprietary technology which embeds PVP in the contact lens during autoclaving. The resulting Dk value of the printed lens material was then used with thickness data to generate true Dk/t profiles for a given lens power. The edge-corrected Dk of the printed etafilcon A lens with offset pigment colorant was measured to be 19.7×10 -11 (cm 2 /s) (mL O 2 /mL·mmHg) at 35°C. This was within ±20% tolerance range as specified in ISO 18369-2:2012(E) for the edge-corrected Dk of the nonpigmented etafilcon A control lens evaluated during the same session, 19.5×10 -11 (cm 2 /s) (mL O 2 /mL·mmHg). The edge-corrected Dk values of the lenses packaged with PVP (mean 20.1, standard deviation [SD] 0.3) were also within the ±20% tolerance range compared to those packaged without PVP (mean 20.0, SD 0.3). The pigment colorant and PVP embedded in the contact lens during autoclaving were not found to influence the oxygen permeability of the etafilcon A material.

Temporal scale dependent interactions between multiple environmental disturbances in microcosm ecosystems.

PubMed

Garnier, Aurélie; Pennekamp, Frank; Lemoine, Mélissa; Petchey, Owen L

2017-12-01

Global environmental change has negative impacts on ecological systems, impacting the stable provision of functions, goods, and services. Whereas effects of individual environmental changes (e.g. temperature change or change in resource availability) are reasonably well understood, we lack information about if and how multiple changes interact. We examined interactions among four types of environmental disturbance (temperature, nutrient ratio, carbon enrichment, and light) in a fully factorial design using a microbial aquatic ecosystem and observed responses of dissolved oxygen saturation at three temporal scales (resistance, resilience, and return time). We tested whether multiple disturbances combine in a dominant, additive, or interactive fashion, and compared the predictability of dissolved oxygen across scales. Carbon enrichment and shading reduced oxygen concentration in the short term (i.e. resistance); although no other effects or interactions were statistically significant, resistance decreased as the number of disturbances increased. In the medium term, only enrichment accelerated recovery, but none of the other effects (including interactions) were significant. In the long term, enrichment and shading lengthened return times, and we found significant two-way synergistic interactions between disturbances. The best performing model (dominant, additive, or interactive) depended on the temporal scale of response. In the short term (i.e. for resistance), the dominance model predicted resistance of dissolved oxygen best, due to a large effect of carbon enrichment, whereas none of the models could predict the medium term (i.e. resilience). The long-term response was best predicted by models including interactions among disturbances. Our results indicate the importance of accounting for the temporal scale of responses when researching the effects of environmental disturbances on ecosystems. © 2017 The Authors. Global Change Biology Published by John Wiley & Sons Ltd.

Integrating Containers in the CERN Private Cloud

NASA Astrophysics Data System (ADS)

Noel, Bertrand; Michelino, Davide; Velten, Mathieu; Rocha, Ricardo; Trigazis, Spyridon

2017-10-01

Containers remain a hot topic in computing, with new use cases and tools appearing every day. Basic functionality such as spawning containers seems to have settled, but topics like volume support or networking are still evolving. Solutions like Docker Swarm, Kubernetes or Mesos provide similar functionality but target different use cases, exposing distinct interfaces and APIs. The CERN private cloud is made of thousands of nodes and users, with many different use cases. A single solution for container deployment would not cover every one of them, and supporting multiple solutions involves repeating the same process multiple times for integration with authentication services, storage services or networking. In this paper we describe OpenStack Magnum as the solution to offer container management in the CERN cloud. We will cover its main functionality and some advanced use cases using Docker Swarm and Kubernetes, highlighting some relevant differences between the two. We will describe the most common use cases in HEP and how we integrated popular services like CVMFS or AFS in the most transparent way possible, along with some limitations found. Finally we will look into ongoing work on advanced scheduling for both Swarm and Kubernetes, support for running batch like workloads and integration of container networking technologies with the CERN infrastructure.

Cation Radical Accelerated Nucleophilic Aromatic Substitution via Organic Photoredox Catalysis.

PubMed

Tay, Nicholas E S; Nicewicz, David A

2017-11-15

Nucleophilic aromatic substitution (S N Ar) is a direct method for arene functionalization; however, it can be hampered by low reactivity of arene substrates and their availability. Herein we describe a cation radical-accelerated nucleophilic aromatic substitution using methoxy- and benzyloxy-groups as nucleofuges. In particular, lignin-derived aromatics containing guaiacol and veratrole motifs were competent substrates for functionalization. We also demonstrate an example of site-selective substitutive oxygenation with trifluoroethanol to afford the desired trifluoromethylaryl ether.

Integrated Anaerobic-Aerobic Biodegradation of Multiple Contaminants Including Chlorinated Ethylenes, Benzene, Toluene, and Dichloromethane.

PubMed

Yoshikawa, Miho; Zhang, Ming; Toyota, Koki

2017-01-01

Complete bioremediation of soils containing multiple volatile organic compounds (VOCs) remains a challenge. To explore the possibility of complete bioremediation through integrated anaerobic-aerobic biodegradation, laboratory feasibility tests followed by alternate anaerobic-aerobic and aerobic-anaerobic biodegradation tests were performed. Chlorinated ethylenes, including tetrachloroethylene (PCE), trichloroethylene (TCE), cis -dichloroethylene ( cis -DCE), and vinyl chloride (VC), and dichloromethane (DCM) were used for anaerobic biodegradation, whereas benzene, toluene, and DCM were used for aerobic biodegradation tests. Microbial communities involved in the biodegradation tests were analyzed to characterize the major bacteria that may contribute to biodegradation. The results demonstrated that integrated anaerobic-aerobic biodegradation was capable of completely degrading the seven VOCs with initial concentration of each VOC less than 30 mg/L. Benzene and toluene were degraded within 8 days, and DCM was degraded within 20 to 27 days under aerobic conditions when initial oxygen concentrations in the headspaces of test bottles were set to 5.3% and 21.0%. Dehalococcoides sp., generally considered sensitive to oxygen, survived aerobic conditions for 28 days and was activated during the subsequent anaerobic biodegradation. However, degradation of cis -DCE was suppressed after oxygen exposure for more than 201 days, suggesting the loss of viability of Dehalococcoides sp., as they are the only known anaerobic bacteria that can completely biodegrade chlorinated ethylenes to ethylene. Anaerobic degradation of DCM following previous aerobic degradation was complete, and yet-unknown microbes may be involved in the process. The findings may provide a scientific and practical basis for the complete bioremediation of multiple contaminants in situ and a subject for further exploration.

Effect of Oxygen-containing Functional Groups on Protein Stability in Ionic Liquid Solutions

NASA Technical Reports Server (NTRS)

Turner, Megan B.; Holbrey, John D.; Spear, Scott K.; Pusey, Marc L.; Rogers, Robin D.

2004-01-01

The ability of functionalized ionic liquids (ILs) to provide an environment of increased stability for biomolecules has been studied. Serum albumin is an inexpensive, widely available protein that contributes to the overall colloid osmotic blood pressure within the vascular system. Albumin is used in the present study as a marker of biomolecular stability in the presence of various ILs in a range of concentrations. The incorporation of hydroxyl functionality into the methylimidazolium-based cation leads to increased protein stability detected by fluorescence spectroscopy and circular dichroic (CD) spectrometry.

About the solubility of reduced SWCNT in DMSO

NASA Astrophysics Data System (ADS)

Guan, Jingwen; Martinez-Rubi, Yadienka; Dénommée, Stéphane; Ruth, Dean; Kingston, Christopher T.; Daroszewska, Malgosia; Barnes, Michael; Simard, Benoit

2009-06-01

Single-walled carbon nanotubes (SWCNT) have been reduced with sodium naphthalide in THF. The reduced SWCNT are not only soluble in dimethylsulfoxide (DMSO) to form a stable solution/suspension, but also react spontaneously at room temperature with DMSO to evolve hydrocarbon gases and are converted into functionalized SWCNT. The degree of functionalization is about 2C% and the addends are mainly methyl and small oxygen-containing hydrocarbons. The functionalized SWCNT are apparently more soluble and stable in DMSO solution. It may open a new era for further processing and applications.

Dissolved oxygen content prediction in crab culture using a hybrid intelligent method

PubMed Central

Yu, Huihui; Chen, Yingyi; Hassan, ShahbazGul; Li, Daoliang

2016-01-01

A precise predictive model is needed to obtain a clear understanding of the changing dissolved oxygen content in outdoor crab ponds, to assess how to reduce risk and to optimize water quality management. The uncertainties in the data from multiple sensors are a significant factor when building a dissolved oxygen content prediction model. To increase prediction accuracy, a new hybrid dissolved oxygen content forecasting model based on the radial basis function neural networks (RBFNN) data fusion method and a least squares support vector machine (LSSVM) with an optimal improved particle swarm optimization(IPSO) is developed. In the modelling process, the RBFNN data fusion method is used to improve information accuracy and provide more trustworthy training samples for the IPSO-LSSVM prediction model. The LSSVM is a powerful tool for achieving nonlinear dissolved oxygen content forecasting. In addition, an improved particle swarm optimization algorithm is developed to determine the optimal parameters for the LSSVM with high accuracy and generalizability. In this study, the comparison of the prediction results of different traditional models validates the effectiveness and accuracy of the proposed hybrid RBFNN-IPSO-LSSVM model for dissolved oxygen content prediction in outdoor crab ponds. PMID:27270206

Dissolved oxygen content prediction in crab culture using a hybrid intelligent method.

PubMed

Yu, Huihui; Chen, Yingyi; Hassan, ShahbazGul; Li, Daoliang

2016-06-08

A precise predictive model is needed to obtain a clear understanding of the changing dissolved oxygen content in outdoor crab ponds, to assess how to reduce risk and to optimize water quality management. The uncertainties in the data from multiple sensors are a significant factor when building a dissolved oxygen content prediction model. To increase prediction accuracy, a new hybrid dissolved oxygen content forecasting model based on the radial basis function neural networks (RBFNN) data fusion method and a least squares support vector machine (LSSVM) with an optimal improved particle swarm optimization(IPSO) is developed. In the modelling process, the RBFNN data fusion method is used to improve information accuracy and provide more trustworthy training samples for the IPSO-LSSVM prediction model. The LSSVM is a powerful tool for achieving nonlinear dissolved oxygen content forecasting. In addition, an improved particle swarm optimization algorithm is developed to determine the optimal parameters for the LSSVM with high accuracy and generalizability. In this study, the comparison of the prediction results of different traditional models validates the effectiveness and accuracy of the proposed hybrid RBFNN-IPSO-LSSVM model for dissolved oxygen content prediction in outdoor crab ponds.

Selective adsorption for removal of nitrogen compounds from hydrocarbon streams over carbon-based adsorbents

NASA Astrophysics Data System (ADS)

Almarri, Masoud S.

The ultimate goal of this thesis is to develop a fundamental understanding of the role of surface oxygen functional groups on carbon-based adsorbents in the adsorption of nitrogen compounds that are known to be present in liquid fuels. N2 adsorption was used to characterize pore structures. The surface chemical properties of the adsorbents were characterized by X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption (TPD) techniques with a mass spectrometer to identify and quantify the type and concentration of oxygen functional groups on the basis of CO2 and CO evolution profiles. It was found that although surface area and pore size distribution are important for the adsorption process, they are not primary factors in the adsorption of nitrogen compounds. On the other hand, both the type and concentration of surface oxygen-containing functional groups play an important role in determining adsorptive denitrogenation performance. Higher concentrations of the oxygen functional groups on the adsorbents resulted in a higher adsorption capacity for the nitrogen compounds. A fundamental insight was gained into the contributions of different oxygen functional groups by analyzing the changes in the monolayer maximum adsorption capacity, qm, and the adsorption constant, K, for nitrogen compounds on different activated carbons. Acidic functional groups such as carboxylic acids and carboxylic anhydrides appear to contribute more to the adsorption of quinoline, while the basic oxygen functional groups such as carbonyls and quinones enhance the adsorption of indole. Despite the high number of publications on the adsorptive desulfurization of liquid hydrocarbon fuels, these studies did not consider the presence of coexisting nitrogen compounds. It is well-known that, to achieve ultraclean diesel fuel, sulfur must be reduced to a very low level, where the concentrations of nitrogen and sulfur compounds are comparable. The adsorptive denitrogenation and desulfurization of model diesel fuel, which contains equimolar concentrations of nitrogen (i.e., quinoline and indole), sulfur (i.e., dibenzothiophene and 4,6-dimethyldibenzothiophene), and aromatic compounds (naphthalene, 1-methylnaphthalene, and fluorene), was examined. The results revealed that when both nitrogen and sulfur compounds coexist in the fuel, the type and density of oxygen functional groups on the surface of the activated carbon are crucial for selective adsorption of nitrogen compounds but have negligible positive effects for sulfur removal. The adsorption of quinoline and indole is largely governed by specific interactions. There is enough evidence to support the importance of dipole--dipole and acid-base-specific interactions for the adsorption of both quinoline and indole. Modified carbon is a promising material for the efficient removal of the nitrogen compounds from light cycle oil (LCO). Adsorptive denitrogenation of LCO significantly improved the hydrodesulfurization (HDS) performance, especially for the removal of the refractory sulfur compounds such as 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene. An essential factor in applying activated carbon for adsorptive denitrogenation and desulfurization of liquid hydrocarbon streams is regeneration after saturation. The regeneration method of the saturated adsorbents consisted of toluene washing followed by heating to remove the remaining toluene. The results show that the spent activated carbon can be regenerated to completely recover the adsorption capacity. The high capacity and selectivity of activated carbon for nitrogen compounds, along with their ability to be regenerated, indicate that activated carbon is a promising adsorbent for the deep denitrogenation of liquid hydrocarbon streams.

Fundamentals of Hydrocarbon Upgrading to Liquid Fuels and Commodity Chemicals over Catalytic Metallic Nanoparticles

NASA Astrophysics Data System (ADS)

Chen, Tao

Promising new technologies for biomass conversion into fuels and chemical feedstocks rely on the production of bio-oils, which need to be upgraded in order to remove oxygen-containing hydrocarbons and water. A high oxygen concentration makes bio-oils acidic and corrosive, unstable during storage, and less energetically valuable per unit weight than petroleum-derived hydrocarbons. Although there are efficient processes for the production of bio-oils, there are no efficient technologies for their upgrading. Current technologies utilize traditional petroleum refining catalysts, which are not optimized for biomass processing. New upgrading technologies are, therefore, urgently needed for development of sustainable energy resources. Development of such new technologies, however, is severely hindered by a lack of fundamental understanding of how oxygen and oxygen-containing hydrocarbons derived from biomass interact with promising noble-metal catalysts. In this study, kinetic reaction measurements, catalyst characterization and quantum chemical calculations using density functional theory were combined for determining adsorption modes and reaction mechanisms of hydrocarbons in the presence of oxygen on surfaces of catalytic noble-metal nanoparticles. The results were used for developing improved catalyst formulations and optimization of reaction conditions. The addition of molybdenum to platinum catalysts was shown to improve catalytic activity, stability, and selectivity in hydrodeoxygenation of acetic acid, which served as a model biomass compound. The fundamental results that describe interactions of oxygen and hydrocarbons with noble-metal catalysts were extended to other reactions and fields of study: evaluation of the reaction mechanism for hydrogen peroxide decomposition, development of improved hydrogenation catalysts and determination of adsorption modes of a spectroscopic probe molecule.

Improving the capacity of lithium-sulfur batteries by tailoring the polysulfide adsorption efficiency of hierarchical oxygen/nitrogen-functionalized carbon host materials.

PubMed

Schneider, Artur; Janek, Jürgen; Brezesinski, Torsten

2017-03-22

The use of monolithic carbons with structural hierarchy and varying amounts of nitrogen and oxygen functionalities as sulfur host materials in high-loading lithium-sulfur cells is reported. The primary focus is on the strength of the polysulfide/carbon interaction with the goal of assessing the effect of (surface) dopant concentration on cathode performance. The adsorption capacity - which is a measure of the interaction strength between the intermediate lithium polysulfide species and the carbon - was found to scale almost linearly with the nitrogen level. Likewise, the discharge capacity of lithium-sulfur cells increased linearly. This positive correlation can be explained by the favorable effect of nitrogen on both the chemical and electronic properties of the carbon host. The incorporation of additional oxygen-containing surface groups into highly nitrogen-functionalized carbon helped to further enhance the polysulfide adsorption efficiency, and therefore the reversible cell capacity. Overall, the areal capacity could be increased by almost 70% to around 3 mA h cm -2 . We believe that the design parameters described here provide a blueprint for future carbon-based nanocomposites for high-performance lithium-sulfur cells.

Kinetics of Organic Transformations Under Mild Aqueous Conditions: Implications for the Origin of Life and Its Metabolism

NASA Technical Reports Server (NTRS)

Weber, Arthur L.

2003-01-01

The rates of thermal transformation of organic molecules containing carbon, hydrogen, and oxygen were systematically examined in order to identify the kinetic constraints that governed origin-of-life organic chemistry under mild aqueous conditions. Arrhenius plots of the kinetic data were used to estimate the reaction half-life at 50 C, and to reveal the effect of functional groups on reactivity. This survey showed that hydrocarbons and organic substances containing a single oxygenated group were kinetically the most stable (i. e. acetate decarboxylation half-life was l0(exp 18) years at 50 C); whereas, organic substances containing two oxygenated groups in which one group was a beta-positioned carbonyl group were the most reactive (i. e. acetoacetate decarboxylation half-life was l0(exp-2) years at 50 C). Of all functional groups the beta-positioned carbonyl group (aldehyde or ketone) was the strongest activating group, giving rates of reaction that were up to 10(exp 24)-times faster than rates of similar molecules lacking the beta-carbonyl group. From this knowledge of organic reactivity and the inherent constraints of autocatalytic processes, we concluded that an origins-of-life process based on autocatalytic transformation of C,H,O-substrates was constrained to using the most reactive organic molecules that contain alpha- or beta-carbonyl groups, since small autocatalytic domains of plausible catalytic power that used less reactive substrates could not carry out chemical transformations fast enough to prevent catastrophic efflux (escape) of reaction intermediates. Knowledge of the kinetics of organic transformations is useful, not only in constraining the chemistry of the earliest autocatalytic process related to the origin of life, but also in establishing the relative reactivity of organic molecules on the early Earth and other planets that may or may not be related to the origin of life.

Rational Design of Mixed-Metal Oxides for Chemical Looping Combustion of Coal via Coupled Computational-Experimental Studies

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

Mishra, Amit; Li, Fanxing; Santiso, Erik

Energy and global climate change are two grand challenges to the modern society. An urgent need exists for development of clean and efficient energy conversion processes. The chemical looping strategy, which utilizes regenerable oxygen carriers (OCs) to indirectly convert carbonaceous fuels via redox reactions, is considered to be one of the more promising approaches for CO2 capture by the U.S. Department of Energy (USDOE). To date, most long-term chemical looping operations were conducted using gaseous fuels, even though direct conversion of coal is more desirable from both economics and CO2 capture viewpoints. The main challenges for direct coal conversion residemore » in the stringent requirements on oxygen carrier performances. In addition, coal char and volatile compounds are more challenging to convert than gaseous fuels. A promising approach for direct conversion of coal is the so called chemical looping with oxygen uncoupling (CLOU) technique. In the CLOU process, a metal oxide that decomposes at the looping temperature, and releases oxygen to the gas phase is used as the OC. The overarching objective of this project was to discover the fundamental principles for rational design and optimization of oxygen carriers (OC) in coal chemical looping combustion (CLC) processes. It directly addresses Topic Area B of the funding opportunity announcement (FOA) in terms of “predictive description of the phase behavior and mechanical properties” of “mixed metal oxide” based OCs and rational development of new OC materials with superior functionality. This was achieved through studies exploring i) iron-containing mixed-oxide composites as oxygen carriers for CLOU, ii) Ca1-xAxMnO3-δ (A = Sr and Ba) as oxygen carriers for CLOU, iii) CaMn1-xBxO3-δ (B=Al, V, Fe, Co, and Ni) as oxygen carrier for CLOU and iv) vacancy creation energy in Mn-containing perovskites as an indicator chemical looping with oxygen uncoupling.« less

Surface Modification of Graphene Oxides by Plasma Techniques and Their Application for Environmental Pollution Cleanup.

PubMed

Wang, Xiangxue; Fan, Qiaohui; Chen, Zhongshan; Wang, Qi; Li, Jiaxing; Hobiny, Aatef; Alsaedi, Ahmed; Wang, Xiangke

2016-02-01

Graphene oxides (GOs) have come under intense multidisciplinary study because of their unique physicochemical properties and possible applications. The large amount of oxygen-containing functional groups on GOs leads to a high sorption capacity for the removal of various kinds of organic and inorganic pollutants from aqueous solutions in environmental pollution cleanup. However, the lack of selectivity results in difficulty in the selective removal of target pollutants from aqueous solutions in the presence of other coexisting pollutants. Herein, the surface grafting of GOs with special oxygen-containing functional groups using low-temperature plasma techniques and the application of the surface-modified GOs for the efficient removal of organic and inorganic pollutants in environmental pollution are reviewed. This paper gives an account of our research on the application of GO-based nanomaterials in environmental pollution cleanup, including: (1) the synthesis and surface grafting of functional groups on GOs, summarizing various types of low-temperature plasma techniques for the synthesis of graphene/GOs; and (2) the application of graphene/GOs and their composites for the efficient removal of organic and inorganic pollutants from aqueous solutions, including the interaction mechanism according to recently published results. © 2015 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Smart Packaging Technologies and Their Application in Conventional Meat Packaging Systems

NASA Astrophysics Data System (ADS)

O'Grady, Michael N.; Kerry, Joseph P.

Preservative packaging of meat and meat products should maintain acceptable appearance, odour and flavour and should delay the onset of microbial spoilage. Typically fresh red meats are placed on trays and over-wrapped with an oxygen permeable film or alternatively, meats are stored in modified atmosphere packages (MAP) containing high levels of oxygen and carbon dioxide (80% O2:20% CO2) (Georgala & Davidson, 1970). Cooked meats are usually stored in 70% N2:30% CO2 (Smiddy, Papkovsky, & Kerry, 2002). The function of oxygen in MAP is to maintain acceptable fresh meat colour and carbon dioxide inhibits the growth of spoilage bacteria (Seideman & Durland, 1984). Nitrogen is used as an inert filler gas either to reduce the proportions of the other gases or to maintain the pack shape (Bell & Bourke, 1996).

Effect of oxidation on transport properties of zirconium-1% niobium alloy

NASA Astrophysics Data System (ADS)

Peletsky, V. E.; Musayeva, Z. A.

1995-11-01

The thermal conductivity and electrical resistivity of zirconium-1 wt% niobium samples were measured before and after the process of their oxidation in air. A special procedure was used to dissolve the gas and to smooth out its concentration in the alloy. The basic experiments were performed under high vacuum under steady-state temperature conditions. The temperature range was 300 1600 K. for the pure alloy and 300 1100 K for the samples containing oxygen. It was found that the thermal conductivity—oxygen concentration relation reverses its sign from negative at low and middle temperatures to positive at temperatures above 900 K. The relation between the electrical resistivity and the oxygen content does not show this feature. The Lorenz function was found to have an anomalous temperature dependence.

Modeling the impact of COPD on the brain.

PubMed

Borson, Soo; Scanlan, James; Friedman, Seth; Zuhr, Elizabeth; Fields, Julie; Aylward, Elizabeth; Mahurin, Rodney; Richards, Todd; Anzai, Yoshimi; Yukawa, Michi; Yeh, Shingshing

2008-01-01

Previous studies have shown that COPD adversely affects distant organs and body systems, including the brain. This pilot study aims to model the relationships between respiratory insufficiency and domains related to brain function, including low mood, subtly impaired cognition, systemic inflammation, and brain structural and neurochemical abnormalities. Nine healthy controls were compared with 18 age- and education-matched medically stable-COPD patients, half of whom were oxygen-dependent. Measures included depression, anxiety, cognition, health status, spirometry, oximetry at rest and during 6-minute walk, and resting plasma cytokines and soluble receptors, brain MRI, and MR spectroscopy in regions relevant to mood and cognition. ANOVA was used to compare controls with patients and with COPD subgroups (oxygen users [n = 9] and nonusers [n = 9]), and only variables showing group differences at p < or = 0.05 were included in multiple regressions controlling for age, gender, and education to develop the final model. Controls and COPD patients differed significantly in global cognition and memory, mood, and soluble TNFR1 levels but not brain structural or neurochemical measures. Multiple regressions identified pathways linking disease severity with impaired performance on sensitive cognitive processing measures, mediated through oxygen dependence, and with systemic inflammation (TNFR1), related through poor 6-minute walk performance. Oxygen desaturation with activity was related to indicators of brain tissue damage (increased frontal choline, which in turn was associated with subcortical white matter attenuation). This empirically derived model provides a conceptual framework for future studies of clinical interventions to protect the brain in patients with COPD, such as earlier oxygen supplementation for patients with desaturation during everyday activities.

Modeling the impact of COPD on the brain

PubMed Central

Borson, Soo; Scanlan, James; Friedman, Seth; Zuhr, Elizabeth; Fields, Julie; Aylward, Elizabeth; Mahurin, Rodney; Richards, Todd; Anzai, Yoshimi; Yukawa, Michi; Yeh, Shingshing

2008-01-01

Previous studies have shown that COPD adversely affects distant organs and body systems, including the brain. This pilot study aims to model the relationships between respiratory insufficiency and domains related to brain function, including low mood, subtly impaired cognition, systemic inflammation, and brain structural and neurochemical abnormalities. Nine healthy controls were compared with 18 age- and education-matched medically stable COPD patients, half of whom were oxygen-dependent. Measures included depression, anxiety, cognition, health status, spirometry, oximetry at rest and during 6-minute walk, and resting plasma cytokines and soluble receptors, brain MRI, and MR spectroscopy in regions relevant to mood and cognition. ANOVA was used to compare controls with patients and with COPD subgroups (oxygen users [n = 9] and nonusers [n = 9]), and only variables showing group differences at p ≤ 0.05 were included in multiple regressions controlling for age, gender, and education to develop the final model. Controls and COPD patients differed significantly in global cognition and memory, mood, and soluble TNFR1 levels but not brain structural or neurochemical measures. Multiple regressions identified pathways linking disease severity with impaired performance on sensitive cognitive processing measures, mediated through oxygen dependence, and with systemic inflammation (TNFR1), related through poor 6-minute walk performance. Oxygen desaturation with activity was related to indicators of brain tissue damage (increased frontal choline, which in turn was associated with subcortical white matter attenuation). This empirically derived model provides a conceptual framework for future studies of clinical interventions to protect the brain in patients with COPD, such as earlier oxygen supplementation for patients with desaturation during everyday activities. PMID:18990971

Quantum mechanical calculations suggest that lytic polysaccharide monooxygenases use a copper-oxyl, oxygen-rebound mechanism

PubMed Central

Kim, Seonah; Ståhlberg, Jerry; Sandgren, Mats; Paton, Robert S.; Beckham, Gregg T.

2014-01-01

Lytic polysaccharide monooxygenases (LPMOs) exhibit a mononuclear copper-containing active site and use dioxygen and a reducing agent to oxidatively cleave glycosidic linkages in polysaccharides. LPMOs represent a unique paradigm in carbohydrate turnover and exhibit synergy with hydrolytic enzymes in biomass depolymerization. To date, several features of copper binding to LPMOs have been elucidated, but the identity of the reactive oxygen species and the key steps in the oxidative mechanism have not been elucidated. Here, density functional theory calculations are used with an enzyme active site model to identify the reactive oxygen species and compare two hypothesized reaction pathways in LPMOs for hydrogen abstraction and polysaccharide hydroxylation; namely, a mechanism that employs a η1-superoxo intermediate, which abstracts a substrate hydrogen and a hydroperoxo species is responsible for substrate hydroxylation, and a mechanism wherein a copper-oxyl radical abstracts a hydrogen and subsequently hydroxylates the substrate via an oxygen-rebound mechanism. The results predict that oxygen binds end-on (η1) to copper, and that a copper-oxyl–mediated, oxygen-rebound mechanism is energetically preferred. The N-terminal histidine methylation is also examined, which is thought to modify the structure and reactivity of the enzyme. Density functional theory calculations suggest that this posttranslational modification has only a minor effect on the LPMO active site structure or reactivity for the examined steps. Overall, this study suggests the steps in the LPMO mechanism for oxidative cleavage of glycosidic bonds. PMID:24344312

COMBAT: A Prospective, Randomized Investigation of Plasma First Resuscitation for Traumatic Hemorrhage and Attenuation of Acute Coagulopathy of Trauma

DTIC Science & Technology

2015-08-01

energy depletion. The latter is accompanied by an increased metabolic rate (including in- creased energy expenditure and oxygen consumption ) (14, 18... consumption in response to maximal oxygen availability predicts postinjury multiple organ failure. J Trauma 33: 58–65; discussion 65–67, 1992. 36... oxygen consumption in response to maximal oxygen availability predicts post- injury multiple organ failure. J Trauma. 1992;33(1):58Y65. 16. Minei JP

COMBAT - A Prospective, Randomized Investigation of Plasma First Resuscitation for Traumatic Hemorrhage and Attenuation of Acute Coagulopathy of Trauma

DTIC Science & Technology

2015-08-01

energy depletion. The latter is accompanied by an increased metabolic rate (including in- creased energy expenditure and oxygen consumption ) (14, 18... consumption in response to maximal oxygen availability predicts postinjury multiple organ failure. J Trauma 33: 58–65; discussion 65–67, 1992. 36... oxygen consumption in response to maximal oxygen availability predicts post- injury multiple organ failure. J Trauma. 1992;33(1):58Y65. 16. Minei JP

On the neutralization in low energy ion scattering spectroscopy (leiss): He + ions on clean and oxygen covered Ni(001) surfaces

NASA Astrophysics Data System (ADS)

Preuss, E.

1981-10-01

A formula for the He + ion survival probability against neutralization is presented, which was derived from the fit of the azimuthal angular dependence of the Ni peak heights on clean and O covered Ni(001) surfaces observed in LEISS experiments and computer simulations. The formula contains a collision- and two Auger-type neutralization terms for the ion trajectories prolonged by multiple collisions above the "neutralization surface plane", which was assumed to be corrugated and shaped like muffin-tins.

Near-Infrared Plasmon-Assisted Water Oxidation.

PubMed

Nishijima, Yoshiaki; Ueno, Kosei; Kotake, Yuki; Murakoshi, Kei; Inoue, Haruo; Misawa, Hiroaki

2012-05-17

We report the stoichiometric evolution of oxygen via water oxidation by irradiating a plasmon-enhanced photocurrent generation system with near-infrared light (λ: 1000 nm), in which gold nanostructures were arrayed on the surface of TiO2 electrode. It is considered that multiple electron holes generated by plasmon-induced charge excitation led to the effective recovery of water oxidation after the electron transfer from gold to TiO2. The proposed system containing a gold nanostructured TiO2 electrode may be a promising artificial photosynthetic system using near-infrared light.

Mapping Resting-State Brain Networks in Conscious Animals

PubMed Central

Zhang, Nanyin; Rane, Pallavi; Huang, Wei; Liang, Zhifeng; Kennedy, David; Frazier, Jean A.; King, Jean

2010-01-01

In the present study we mapped brain functional connectivity in the conscious rat at the “resting state” based on intrinsic blood-oxygenation-level dependent (BOLD) fluctuations. The conscious condition eliminated potential confounding effects of anesthetic agents on the connectivity between brain regions. Indeed, using correlational analysis we identified multiple cortical and subcortical regions that demonstrated temporally synchronous variation with anatomically well-defined regions that are crucial to cognitive and emotional information processing including the prefrontal cortex (PFC), thalamus and retrosplenial cortex. The functional connectivity maps created were stringently validated by controlling for false positive detection of correlation, the physiologic basis of the signal source, as well as quantitatively evaluating the reproducibility of maps. Taken together, the present study has demonstrated the feasibility of assessing functional connectivity in conscious animals using fMRI and thus provided a convenient and non-invasive tool to systematically investigate the connectional architecture of selected brain networks in multiple animal models. PMID:20382183

The protective role of isorhamnetin on human brain microvascular endothelial cells from cytotoxicity induced by methylglyoxal and oxygen-glucose deprivation.

PubMed

Li, Wenlu; Chen, Zhigang; Yan, Min; He, Ping; Chen, Zhong; Dai, Haibin

2016-02-01

As the first target of stroke, cerebral endothelial cells play a key role in brain vascular repair and maintenance, and their function is impeded in diabetes. Methylglyoxal (MGO), a reactive dicarbonyl produced during glucose metabolism, accumulates in diabetic patients. MGO and MGO-induced advanced glycation end-products (AGEs) could ameliorate stroke-induced brain vascular damage, closely related with ECs dysfunction. Using MGO plus oxygen-glucose deprivation (OGD) to mimic diabetic stroke, we reported the protective effect of isorhamnetin on OGD-induced cytotoxicity after MGO treatment on primary human brain microvascular endothelial cells (HBMEC) and explored the underlying mechanisms. Treatment of MGO for 24 h significantly enhanced 3-h OGD-induced HBMEC toxic effect, which was inhibited by pretreatment of isorhamnetin (100 μmol/L). Moreover, the protective effect of isorhamnetin is multiple function dependent, which includes anti-inflammation, anti-oxidative stress and anti-apoptosis effects. Besides its well-known inhibition on the mitochondria-dependent or intrinsic apoptotic pathway, isorhamnetin also reduced activation of the extrinsic apoptotic pathway, as characterized by the decreased expression and activity of caspase 3 and caspase 8. Furthermore, pretreatment with isorhamnetin specifically inhibited FAS/FASL expression and suppressed nuclear factor-kappa B nuclear translocation. Taken together, our results indicated that isorhamnetin protected against OGD-induced cytotoxicity after MGO treatment in cultured HBMEC due to its multiple protective effects and could inhibit Fas-mediated extrinsic apoptosis. Therefore, isorhamnetin is a promising reagent for the treatment of hyperglycemia and ischemia-induced cerebral vascular degeneration. A proposed model of the potential protective mechanism of isorhamnetin, a metabolite of quercetin, on methylglyoxal (MGO) treatment plus oxygen-glucose deprivation (OGD) exposure-induced cytotoxicity in cultured human brain microvascular endothelial cells. Isorhamnetin inhibits FasL-mediated extrinsic apoptosis and neurotrophic factor κB (NF-κB) nuclear translocation, which can induce the cell DNA damage. Therefore, the protective effect of isorhamnetin occurs through multiple functions, including anti-inflammation, anti-oxidative stress and anti-apoptosis. Therefore, isorhamnetin is a promising reagent for the treatment of hyperglycemia and ischemia-induced cerebral vascular degeneration. © 2015 International Society for Neurochemistry.

The Role of Reactive Oxygen Species (ROS) in the Biological Activities of Metallic Nanoparticles

PubMed Central

Abdal Dayem, Ahmed; Hossain, Mohammed Kawser; Lee, Soo Bin; Kim, Kyeongseok; Saha, Subbroto Kumar; Yang, Gwang-Mo; Choi, Hye Yeon; Cho, Ssang-Goo

2017-01-01

Nanoparticles (NPs) possess unique physical and chemical properties that make them appropriate for various applications. The structural alteration of metallic NPs leads to different biological functions, specifically resulting in different potentials for the generation of reactive oxygen species (ROS). The amount of ROS produced by metallic NPs correlates with particle size, shape, surface area, and chemistry. ROS possess multiple functions in cellular biology, with ROS generation a key factor in metallic NP-induced toxicity, as well as modulation of cellular signaling involved in cell death, proliferation, and differentiation. In this review, we briefly explained NP classes and their biomedical applications and describe the sources and roles of ROS in NP-related biological functions in vitro and in vivo. Furthermore, we also described the roles of metal NP-induced ROS generation in stem cell biology. Although the roles of ROS in metallic NP-related biological functions requires further investigation, modulation and characterization of metallic NP-induced ROS production are promising in the application of metallic NPs in the areas of regenerative medicine and medical devices. PMID:28075405

Materials characterization of impregnated W and W-Ir cathodes after oxygen poisoning

NASA Astrophysics Data System (ADS)

Polk, James E.; Capece, Angela M.

2015-05-01

Electric thrusters use hollow cathodes as the electron source for generating the plasma discharge and for beam neutralization. These cathodes contain porous tungsten emitters impregnated with BaO material to achieve a lower surface work function and are operated with xenon propellant. Oxygen contaminants in the xenon plasma can poison the emitter surface, resulting in a higher work function and increased operating temperature. This could lead directly to cathode failure by preventing discharge ignition or could accelerate evaporation of the BaO material. Exposures over hundreds of hours to very high levels of oxygen can result in increased temperatures, oxidation of the tungsten substrate, and the formation of surface layers of barium tungstates. In this work, we present results of a cathode test in which impregnated tungsten and tungsten-iridium emitters were operated with 100 ppm of oxygen in the xenon plasma for several hundred hours. The chemical and morphological changes were studied using scanning electron microscopy, energy dispersive spectroscopy, and laser profilometry. The results provide strong evidence that high concentrations of oxygen accelerate the formation of tungstate layers in both types of emitters, a phenomenon not inherent to normal cathode operation. Deposits of pure tungsten were observed on the W-Ir emitter, indicating that tungsten is preferentially removed from the surface and transported in the insert plasma. A W-Ir cathode surface will therefore evolve to a pure W composition, eliminating the work function benefit of W-Ir. However, the W-Ir emitter exhibited less erosion and redeposition at the upstream end than the pure W emitter.

Catalytic, Enantioselective Sulfenofunctionalisation of Alkenes: Mechanistic, Crystallographic, and Computational Studies

PubMed Central

Denmark, Scott E.; Hartmann, Eduard; Kornfilt, David J. P.; Wang, Hao

2015-01-01

The stereocontrolled introduction of vicinal heteroatomic substituents into organic molecules is one of the most powerful ways of adding value and function. Whereas many methods exist for the introduction of oxygen- and nitrogen-containing substituents, the number stereocontrolled methods for the introduction of sulfur-containing substituents pales by comparison. Previous reports from these laboratories have described the sulfenofunctionalization of alkenes that construct vicinal carbon-sulfur and carbon-oxygen, carbon-nitrogen as well as carbon-carbon bonds with high levels of diastereospecificity and enantioselectivity. This process is enabled by the concept of Lewis base activation of Lewis acids that provides activation of Group 16 electrophiles. To provide a foundation for expansion of substrate scope and improved selectivities, we have undertaken a comprehensive study of the catalytically active species. Insights gleaned from kinetic, crystallographic and computational methods have led to the introduction of a new family of sulfenylating agents that provide significantly enhanced selectivities. PMID:25411883

Calcium EXAFS Establishes the Mn-Ca Cluster in the Oxygen-Evolving Complex of Photosystem II†

PubMed Central

Cinco, Roehl M.; Holman, Karen L. McFarlane; Robblee, John H.; Yano, Junko; Pizarro, Shelly A.; Bellacchio, Emanuele; Sauer, Kenneth; Yachandra, Vittal K.

2014-01-01

The proximity of Ca to the Mn cluster of the photosynthetic water-oxidation complex is demonstrated by X-ray absorption spectroscopy. We have collected EXAFS data at the Ca K-edge using active PS II membrane samples that contain approximately 2 Ca per 4 Mn. These samples are much less perturbed than previously investigated Sr-substituted samples, which were prepared subsequent to Ca depletion. The new Ca EXAFS clearly shows backscattering from Mn at 3.4 Å, a distance that agrees with that surmised from previously recorded Mn EXAFS. This result is also consistent with earlier related experiments at the Sr K-edge, using samples that contained functional Sr, that show Mn is ~ 3.5 Å distant from Sr. The totality of the evidence clearly advances the notion that the catalytic center of oxygen evolution is a Mn-Ca heteronuclear cluster. PMID:12390018

Theoretical study of interactions between cysteine and perfluoropropanoic acid in gas and aqueous phase

NASA Astrophysics Data System (ADS)

Holmes, Tiffani M.; Doskocz, Jacek; Wright, Terrance; Hill, Glake A.

The interaction of perfluoropropanoic acid (PFPA) with the amino acid cysteine was investigated using density functional theory. Previous studies suggest that the peroxisome proliferator chemical, perfluorooctanoic acid, is circulated throughout the body by way of sulfur-containing amino acids. We present conformational analysis of the interactions of PFPA, a small model of perfluorooctanoic acid, with the sulfur-containing amino acid which occur by the process of hydrogen bonding, in which the hydrogen of the sulfhydryl group interacts with the carboxyl oxygen, and the amino nitrogen forms a hydrogen bond with the hydrogen of the bond OH group of the fluorinated alkyl. We also show in our structures a recently characterized weak nonbonded interaction between divalent sulfur and a main chain carboxyl oxygen in proteins. B3LYP calculated free energies and interaction energies predict low-energy, high-interaction conformations for complex systems of perfluorinated fatty acid interactions with cysteine.

Isotope exchange in oxide-containing catalyst

NASA Technical Reports Server (NTRS)

Brown, Kenneth G. (Inventor); Upchurch, Billy T. (Inventor); Hess, Robert V. (Inventor); Miller, Irvin M. (Inventor); Schryer, David R. (Inventor); Sidney, Barry D. (Inventor); Wood, George M. (Inventor); Hoyt, Ronald F. (Inventor)

1989-01-01

A method of exchanging rare-isotope oxygen for common-isotope oxygen in the top several layers of an oxide-containing catalyst is disclosed. A sample of an oxide-containing catalyst is exposed to a flowing stream of reducing gas in an inert carrier gas at a temperature suitable for the removal of the reactive common-isotope oxygen atoms from the surface layer or layers of the catalyst without damaging the catalyst structure. The reduction temperature must be higher than any at which the catalyst will subsequently operate. Sufficient reducing gas is used to allow removal of all the reactive common-isotope oxygen atoms in the top several layers of the catalyst. The catalyst is then reoxidized with the desired rare-isotope oxygen in sufficient quantity to replace all of the common-isotope oxygen that was removed.

Effects of oxygen content on the oxidation process of Si-containing steel during anisothermal heating

NASA Astrophysics Data System (ADS)

Yuan, Qing; Xu, Guang; Liang, Wei-cheng; He, Bei; Zhou, Ming-xing

2018-02-01

The oxidizing behavior of Si-containing steel was investigated in an O2 and N2 binary-component gas with oxygen contents ranging between 0.5vol% and 4.0vol% under anisothermal-oxidation conditions. A simultaneous thermal analyzer was employed to simulate the heating process of Si-containing steel in industrial reheating furnaces. The oxidation gas mixtures were introduced from the commencement of heating. The results show that the oxidizing rate remains constant in the isothermal holding process at high temperatures; therefore, the mass change versus time presents a linear law. A linear relation also exists between the oxidizing rate and the oxygen content. Using the linear regression equation, the oxidation rate at different oxygen contents can be predicted. In addition, the relationship between the total mass gain and the oxygen content is linear; thus, the total mass gain at oxygen contents between 0.5vol%-4.0vol% can be determined. These results enrich the theoretical studies of the oxidation process in Si-containing steels.

High-temperature potentiometric oxygen sensor with internal reference

DOEpatents

Routbort, Jules L [Hinsdale, IL; Singh, Dileep [Naperville, IL; Dutta, Prabir K [Worthington, OH; Ramasamy, Ramamoorthy [North Royalton, OH; Spirig, John V [Columbus, OH; Akbar, Sheikh [Hilliard, OH

2011-11-15

A compact oxygen sensor is provided, comprising a mixture of metal and metal oxide an enclosure containing said mixture, said enclosure capable of isolating said mixture from an environment external of said enclosure, and a first wire having a first end residing within the enclosure and having a second end exposed to the environment. Also provided is a method for the fabrication of an oxygen sensor, the method comprising confining a metal-metal oxide solid mixture to a container which consists of a single material permeable to oxygen ions, supplying an electrical conductor having a first end and a second end, whereby the first end resides inside the container as a reference (PO.sub.2).sup.ref, and the second end resides outside the container in the atmosphere where oxygen partial pressure (PO.sub.2).sup.ext is to be measured, and sealing the container with additional single material such that grain boundary sliding occurs between grains of the single material and grains of the additional single material.

A Unified Approach to Functional Principal Component Analysis and Functional Multiple-Set Canonical Correlation.

PubMed

Choi, Ji Yeh; Hwang, Heungsun; Yamamoto, Michio; Jung, Kwanghee; Woodward, Todd S

2017-06-01

Functional principal component analysis (FPCA) and functional multiple-set canonical correlation analysis (FMCCA) are data reduction techniques for functional data that are collected in the form of smooth curves or functions over a continuum such as time or space. In FPCA, low-dimensional components are extracted from a single functional dataset such that they explain the most variance of the dataset, whereas in FMCCA, low-dimensional components are obtained from each of multiple functional datasets in such a way that the associations among the components are maximized across the different sets. In this paper, we propose a unified approach to FPCA and FMCCA. The proposed approach subsumes both techniques as special cases. Furthermore, it permits a compromise between the techniques, such that components are obtained from each set of functional data to maximize their associations across different datasets, while accounting for the variance of the data well. We propose a single optimization criterion for the proposed approach, and develop an alternating regularized least squares algorithm to minimize the criterion in combination with basis function approximations to functions. We conduct a simulation study to investigate the performance of the proposed approach based on synthetic data. We also apply the approach for the analysis of multiple-subject functional magnetic resonance imaging data to obtain low-dimensional components of blood-oxygen level-dependent signal changes of the brain over time, which are highly correlated across the subjects as well as representative of the data. The extracted components are used to identify networks of neural activity that are commonly activated across the subjects while carrying out a working memory task.

Identification of selenium-containing proteins in HEK 293 kidney cells using multiple chromatographies, LC-ICPMS and nano-LC-ESIMS.

PubMed

Chitta, Karnakar R; Landero-Figueroa, Julio A; Kodali, Phanichand; Caruso, Joseph A; Merino, Edward J

2013-09-30

Our previous studies using HeLa and HEK 293 cells demonstrated that selenomethionine, SeMet, exerts more of an antagonistic effect on arsenic than other selenium species. These studies attributed the antagonistic effect of SeMet to decreased levels of reactive oxygen species, ROS, changes in protein phosphorylation and possible incorporation of SeMet into proteins. The present study employs a metallomics approach to identify the selenium-containing proteins in HEK 293 cells raised with SeMet. The proteins were screened and separated using two dimensional high performance liquid chromatography (HPLC)-inductively coupled plasma mass spectrometry (ICPMS), size exclusion chromatography (SEC) and reversed-phase chromatography (RPC). The Se-containing proteins were identified by peptide mapping using nano-HPLC-Chip-electrospray ionization mass spectrometry (ESIMS). Copyright © 2013 Elsevier B.V. All rights reserved.

Oxygen Activation and Radical Transformations in Heme Proteins and Metalloporphyrins

PubMed Central

2017-01-01

As a result of the adaptation of life to an aerobic environment, nature has evolved a panoply of metalloproteins for oxidative metabolism and protection against reactive oxygen species. Despite the diverse structures and functions of these proteins, they share common mechanistic grounds. An open-shell transition metal like iron or copper is employed to interact with O2 and its derived intermediates such as hydrogen peroxide to afford a variety of metal–oxygen intermediates. These reactive intermediates, including metal-superoxo, -(hydro)peroxo, and high-valent metal–oxo species, are the basis for the various biological functions of O2-utilizing metalloproteins. Collectively, these processes are called oxygen activation. Much of our understanding of the reactivity of these reactive intermediates has come from the study of heme-containing proteins and related metalloporphyrin compounds. These studies not only have deepened our understanding of various functions of heme proteins, such as O2 storage and transport, degradation of reactive oxygen species, redox signaling, and biological oxygenation, etc., but also have driven the development of bioinorganic chemistry and biomimetic catalysis. In this review, we survey the range of O2 activation processes mediated by heme proteins and model compounds with a focus on recent progress in the characterization and reactivity of important iron–oxygen intermediates. Representative reactions initiated by these reactive intermediates as well as some context from prior decades will also be presented. We will discuss the fundamental mechanistic features of these transformations and delineate the underlying structural and electronic factors that contribute to the spectrum of reactivities that has been observed in nature as well as those that have been invented using these paradigms. Given the recent developments in biocatalysis for non-natural chemistries and the renaissance of radical chemistry in organic synthesis, we envision that new enzymatic and synthetic transformations will emerge based on the radical processes mediated by metalloproteins and their synthetic analogs. PMID:29286645

Structural elucidation of direct analysis in real time ionized nerve agent simulants with infrared multiple photon dissociation spectroscopy.

PubMed

Rummel, Julia L; Steill, Jeffrey D; Oomens, Jos; Contreras, Cesar S; Pearson, Wright L; Szczepanski, Jan; Powell, David H; Eyler, John R

2011-06-01

Infrared multiple photon dissociation (IRMPD) was used to generate vibrational spectra of ions produced with a direct analysis in real time (DART) ionization source coupled to a 4.7 T Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. The location of protonation on the nerve agent simulants diisopropyl methylphosphonate (DIMP) and dimethyl methylphosphonate (DMMP) was studied while solutions of the compounds were introduced for extended periods of time with a syringe pump. Theoretical vibrational spectra were generated with density functional theory calculations. Visual comparison of experimental mid-IR IRMPD spectra and theoretical spectra could not establish definitively if a single structure or a mixture of conformations was present for the protonated parent of each compound. However, theoretical calculations, near-ir IRMPD spectra, and frequency-to-frequency and statistical comparisons indicated that the protonation site for both DIMP and DMMP was predominantly, if not exclusively, the phosphonyl oxygen instead of one of the oxygen atoms with only single bonds.

On the preservation of laminated sediments along the western margin of North America

USGS Publications Warehouse

VanGeen, A.; Zheng, Yen; Bernhard, J.M.; Cannariato, K.G.; Carriquiry, J.; Dean, W.E.; Eakins, B.W.; Ortiz, J.D.; Pike, J.

2003-01-01

Piston, gravity, and multicores as well as hydrographic data were collected along the Pacific margin of Baja California to reconstruct past variations in the intensity of the oxygen-minimum zone (OMZ). Gravity cores collected from within the OMZ north of 24??N did not contain laminated surface sediments even though bottom water oxygen (BWO) concentrations were close to 5 ??mol/kg. However, many of the cores collected south of 24??N did contain millimeter- to centimeter-scale, brown to black laminations in Holocene and older sediments but not in sediments deposited during the Last Glacial Maximum. In addition to the dark laminations, Holocene sediments in Soledad Basin, silled at 290 m, also contain white coccolith laminae that probably represent individual blooms. Two open margin cores from 430 and 700 m depth that were selected for detailed radiocarbon dating show distinct transitions from bioturbated glacial sediment to laminated Holocene sediment occurring at 12.9 and 11.5 ka, respectively. The transition is delayed and more gradual (11.3-10.0 ka) in another dated core from Soledad Basin. The observations indicate that bottom-water oxygen concentrations dropped below a threshold for the preservation of laminations at different times or that a synchronous hydrographic change left an asynchronous sedimentary imprint due to local factors. With the caveat that laminated sections should therefore not be correlated without independent age control, the pattern of older sequences of laminations along the North American western margin reported by this and previous studies suggests that multiple patterns of regional productivity and ventilation prevailed over the past 60 kyr. Copyright 2003 by the American Geophysical Union.

Oxygen acceleration in magnetotail reconnection

NASA Astrophysics Data System (ADS)

Liang, Haoming; Lapenta, Giovanni; Walker, Raymond J.; Schriver, David; El-Alaoui, Mostafa; Berchem, Jean

2017-01-01

Motivated by the observed high concentration of oxygen ions in the magnetotail during enhanced geomagnetic activity, we investigated the oxygen acceleration in magnetotail reconnection by using 2.5-D implicit particle-in-cell simulations. We found that lobe oxygen ions can enter the downstream outflow region, i.e., the outflow region downstream of the dipolarization fronts (DFs) or the reconnection jet fronts. Without entering the reconnection exhaust, they are accelerated by the Hall electric field. They can populate the downstream outflow region before the DFs arrive there. This acceleration is in addition to acceleration in the exhaust by the Hall and reconnection electric fields. Oxygen ions in the preexisting current sheet are reflected by the propagating DF creating a reflected beam with a hook shape in phase space. This feature can be applied to deduce a history of the DF speed. However, it is difficult to observe for protons because their typical thermal velocity in the plasma sheet is comparable those of the DF and the reflection speed. The oxygen ions from the lobes and the preexisting current sheet form multiple beams in the distribution function in front of the DF. By comparing oxygen concentrations of 50%, 5%, and 0% with the same current sheet thickness, we found that the DF thickness is proportional to the oxygen concentration in the preexisting current sheet. All the simulation results can be used to compare with the observations from the Magnetospheric Multiscale mission.

Molecular evolution and expression of oxygen transport genes in livebearing fishes (Poeciliidae) from hydrogen sulfide rich springs.

PubMed

Barts, Nicholas; Greenway, Ryan; Passow, Courtney N; Arias-Rodriguez, Lenin; Kelley, Joanna L; Tobler, Michael

2018-04-01

Hydrogen sulfide (H 2 S) is a natural toxicant in some aquatic environments that has diverse molecular targets. It binds to oxygen transport proteins, rendering them non-functional by reducing oxygen-binding affinity. Hence, organisms permanently inhabiting H 2 S-rich environments are predicted to exhibit adaptive modifications to compensate for the reduced capacity to transport oxygen. We investigated 10 lineages of fish of the family Poeciliidae that have colonized freshwater springs rich in H 2 S-along with related lineages from non-sulfidic environments-to test hypotheses about the expression and evolution of oxygen transport genes in a phylogenetic context. We predicted shifts in the expression of and signatures of positive selection on oxygen transport genes upon colonization of H 2 S-rich habitats. Our analyses indicated significant shifts in gene expression for multiple hemoglobin genes in lineages that have colonized H 2 S-rich environments, and three hemoglobin genes exhibited relaxed selection in sulfidic compared to non-sulfidic lineages. However, neither changes in gene expression nor signatures of selection were consistent among all lineages in H 2 S-rich environments. Oxygen transport genes may consequently be predictable targets of selection during adaptation to sulfidic environments, but changes in gene expression and molecular evolution of oxygen transport genes in H 2 S-rich environments are not necessarily repeatable across replicated lineages.

Closed-Cycle Hydrogen-Oxygen Regenerative Fuel Cell at the NASA Glenn Research Center-An Update

NASA Technical Reports Server (NTRS)

Bents, David J.; Chang, Bei-Jiann; Johnson, Donald W.; Garcia, Christopher P.

2008-01-01

The closed cycle hydrogen-oxygen proton exchange membrane (PEM) regenerative fuel cell (RFC) at the NASA Glenn Research Center has demonstrated multiple back-to-back contiguous cycles at rated power and round-trip efficiencies up to 52 percent. It is the first fully closed cycle RFC ever demonstrated. (The entire system is sealed; nothing enters or escapes the system other than electrical power and heat.) During fiscal year fiscal year (FY) FY06 to FY07, the system s numerous modifications and internal improvements focused on reducing parasitic power, heat loss, and noise signature; increasing its functionality as an unattended automated energy storage device; and in-service reliability.

Micro-oxidation treatment to improve bonding strength of Sr and Na co-substituted hydroxyapatite coatings for carbon/carbon composites

NASA Astrophysics Data System (ADS)

Zhang, Leilei; Li, Hejun; Li, Kezhi; Zhang, Yulei; Liu, Shoujie; Guo, Qian; Li, Shaoxian

2016-08-01

To improve the bonding strength of Sr and Na co-substituted hydroxyapatite (SNH) coatings for carbon/carbon composites, carbon/carbon composites are surface modified by micro-oxidation treatment. The micro-oxidation treatment could generate large number of pores containing oxygenic functional groups on the surface of carbon/carbon composites. SNH is nucleated on the inwall of the pores and form a flaky shape coating with 10-50 nm in thickness and 200-900 nm in width. The bonding strength between SNH coating and carbon/carbon composites increases from 4.27 ± 0.26 MPa to 10.57 ± 0.38 MPa after the micro-oxidation treatment. The promotion of bonding strength is mainly attributed to the pinning effect caused by the pores and chemical bonding generated by the oxygenic functional groups.

Photochemical Properties and Reactivity of a Ru Compound Containing an NAD/NADH-Functionalized 1,10-Phenanthroline Ligand.

PubMed

Kobayashi, Katsuaki; Ohtsu, Hideki; Nozaki, Koichi; Kitagawa, Susumu; Tanaka, Koji

2016-03-07

An NAD/NADH-functionalized ligand, benzo[b]pyrido[3,2-f][1,7]-phenanthroline (bpp), was newly synthesized. A Ru compound containing the bpp ligand, [Ru(bpp)(bpy)2](2+), underwent 2e(-) and 2H(+) reduction, generating the NADH form of the compound, [Ru(bppHH)(bpy)2](2+), in response to visible light irradiation in CH3CN/TEA/H2O (8/1/1). The UV-vis and fluorescent spectra of both [Ru(bpp)(bpy)2](2+) and [Ru(bppHH)(bpy)2](2+) resembled the spectra of [Ru(bpy)3](2+). Both complexes exhibited strong emission, with quantum yields of 0.086 and 0.031, respectively; values that are much higher than those obtained from the NAD/NADH-functionalized complexes [Ru(pbn)(bpy)2](2+) and [Ru(pbnHH)(bpy)2](2+) (pbn = (2-(2-pyridyl)benzo[b]-1.5-naphthyridine, pbnHH = hydrogenated form of pbn). The reduction potential of the bpp ligand in [Ru(bpp)(bpy)2](2+) (-1.28 V vs SCE) is much more negative than that of the pbn ligand in [Ru(pbn)(bpy)2](2+) (-0.74 V), although the oxidation potentials of bppHH and pbnHH are essentially equal (0.95 V). These results indicate that the electrochemical oxidation of the dihydropyridine moiety in the NADH-type ligand was independent of the π system, including the Ru polypyridyl framework. [Ru(bppHH)(bpy)2](2+) allowed the photoreduction of oxygen, generating H2O2 in 92% yield based on [Ru(bppHH)(bpy)2](2+). H2O2 production took place via singlet oxygen generated by the energy transfer from excited [Ru(bppHH)(bpy)2](2+) to triplet oxygen.

Improvement of oxygen-containing functional groups on olive stones activated carbon by ozone and nitric acid for heavy metals removal from aqueous phase.

PubMed

Bohli, Thouraya; Ouederni, Abdelmottaleb

2016-08-01

Recently, modification of surface structure of activated carbons in order to improve their adsorption performance toward especial pollutants has gained great interest. Oxygen-containing functional groups have been devoted as the main responsible for heavy metal binding on the activated carbon surface; their introduction or enhancement needs specific modification and impregnation methods. In the present work, olive stones activated carbon (COSAC) undergoes surface modifications in gaseous phase using ozone (O3) and in liquid phase using nitric acid (HNO3). The activated carbon samples were characterized using N2 adsorption-desorption isotherm, SEM, pHpzc, FTIR, and Boehm titration. The activated carbon parent (COSAC) has a high surface area of 1194 m(2)/g and shows a predominantly microporous structure. Oxidation treatments with nitric acid and ozone show a decrease in both specific surface area and micropore volumes, whereas these acidic treatments have led to a fixation of high amount of surface oxygen functional groups, thus making the carbon surface more hydrophilic. Activated carbon samples were used as an adsorbent matrix for the removal of Co(II), Ni(II), and Cu(II) heavy metal ions from aqueous solutions. Adsorption isotherms were obtained at 30 °C, and the data are well fitted to the Redlich-Peterson and Langmuir equation. Results show that oxidized COSACs, especially COSAC(HNO3), are capable to remove more Co(II), Cu(II), and Ni(II) from aqueous solution. Nitric acid-oxidized olive stones activated carbon was tested in its ability to remove metal ions from binary systems and results show an important maximum adsorbed amount as compared to single systems.

Melt containment member

DOEpatents

Rieken, Joel R.; Heidloff, Andrew J.

2014-09-09

A tubular melt containment member for transient containment of molten metals and alloys, especially reactive metals and alloys, includes a melt-contacting layer or region that comprises an oxygen-deficient rare earth oxide material that is less reactive as compared to the counterpart stoichiometric rare earth oxide. The oxygen-deficient (sub-stoichiometric) rare earth oxide can comprise oxygen-deficient yttria represented by Y.sub.2O.sub.3-x wherein x is from 0.01 to 0.1. Use of the oxygen-deficient rare earth oxide as the melt-contacting layer or region material reduces reaction with the melt for a given melt temperature and melt contact time.

Vector Communication Curriculum: Moderate and Severe, Multiple Disabilities.

ERIC Educational Resources Information Center

Baine, David

This CD-ROM disk contains a curriculum on vector communication for students with moderate and severe multiple disabilities. Section 1 discusses pragmatic communication, functional analysis of behavior, augmentative and alternative communication, including gestures and signs, use of pictures and pictographs, and low, medium, and high tech…

Oxygen supersaturated fluid using fine micro/nanobubbles

PubMed Central

Matsuki, Noriaki; Ishikawa, Takuji; Ichiba, Shingo; Shiba, Naoki; Ujike, Yoshihito; Yamaguchi, Takami

2014-01-01

Microbubbles show peculiar properties, such as shrinking collapse, long lifetime, high gas solubility, negative electric charge, and free radical production. Fluids supersaturated with various gases can be easily generated using microbubbles. Oxygen microbubble fluid can be very useful for oxygen delivery to hypoxic tissues. However, there have been no reports of comparative investigations into adding fluids containing oxygen fine micro/nanobubbles (OFM-NBs) to common infusion solutions in daily medical care. In this study, it was demonstrated that OFMNBs can generate oxygen-supersaturated fluids, and they may be sufficiently small to infuse safely into blood vessels. It was found that normal saline solution is preferable for generating an oxygen-rich infusion fluid, which is best administered as a 30-minute intravenous infusion. It was also concluded that dextran solution is suitable for drug delivery substances packing oxygen gas over a 1-hour intravenous infusion. In addition, normal saline solution containing OFMNBs was effective for improving blood oxygenation. Thus, the use of OFMNB-containing fluids is a potentially effective novel method for improving blood oxygenation in cases involving hypoxia, ischemic diseases, infection control, and anticancer chemoradiation therapies. PMID:25285003

Oxygen supersaturated fluid using fine micro/nanobubbles.

PubMed

Matsuki, Noriaki; Ishikawa, Takuji; Ichiba, Shingo; Shiba, Naoki; Ujike, Yoshihito; Yamaguchi, Takami

2014-01-01

Microbubbles show peculiar properties, such as shrinking collapse, long lifetime, high gas solubility, negative electric charge, and free radical production. Fluids supersaturated with various gases can be easily generated using microbubbles. Oxygen microbubble fluid can be very useful for oxygen delivery to hypoxic tissues. However, there have been no reports of comparative investigations into adding fluids containing oxygen fine micro/nanobubbles (OFM-NBs) to common infusion solutions in daily medical care. In this study, it was demonstrated that OFMNBs can generate oxygen-supersaturated fluids, and they may be sufficiently small to infuse safely into blood vessels. It was found that normal saline solution is preferable for generating an oxygen-rich infusion fluid, which is best administered as a 30-minute intravenous infusion. It was also concluded that dextran solution is suitable for drug delivery substances packing oxygen gas over a 1-hour intravenous infusion. In addition, normal saline solution containing OFMNBs was effective for improving blood oxygenation. Thus, the use of OFMNB-containing fluids is a potentially effective novel method for improving blood oxygenation in cases involving hypoxia, ischemic diseases, infection control, and anticancer chemoradiation therapies.

Heat Pipe Solar Receiver for Oxygen Production of Lunar Regolith

NASA Astrophysics Data System (ADS)

Hartenstine, John R.; Anderson, William G.; Walker, Kara L.; Ellis, Michael C.

2009-03-01

A heat pipe solar receiver operating in the 1050° C range is proposed for use in the hydrogen reduction process for the extraction of oxygen from the lunar soil. The heat pipe solar receiver is designed to accept, isothermalize and transfer solar thermal energy to reactors for oxygen production. This increases the available area for heat transfer, and increases throughput and efficiency. The heat pipe uses sodium as the working fluid, and Haynes 230 as the heat pipe envelope material. Initial design requirements have been established for the heat pipe solar receiver design based on information from the NASA In-Situ Resource Utilization (ISRU) program. Multiple heat pipe solar receiver designs were evaluated based on thermal performance, temperature uniformity, and integration with the solar concentrator and the regolith reactor(s). Two designs were selected based on these criteria: an annular heat pipe contained within the regolith reactor and an annular heat pipe with a remote location for the reactor. Additional design concepts have been developed that would use a single concentrator with a single solar receiver to supply and regulate power to multiple reactors. These designs use variable conductance or pressure controlled heat pipes for passive power distribution management between reactors. Following the design study, a demonstration heat pipe solar receiver was fabricated and tested. Test results demonstrated near uniform temperature on the outer surface of the pipe, which will ultimately be in contact with the regolith reactor.

Measurement of cell respiration and oxygenation in standard multichannel biochips using phosphorescent O2-sensitive probes.

PubMed

Kondrashina, Alina V; Papkovsky, Dmitri B; Dmitriev, Ruslan I

2013-09-07

Measurement of cell oxygenation and oxygen consumption is useful for studies of cell bioenergetics, metabolism, mitochondrial function, drug toxicity and common pathophysiological conditions. Here we present a new platform for such applications which uses commercial multichannel biochips (μ-slides, Ibidi) and phosphorescent O2 sensitive probes. This platform was evaluated with both extracellular and intracellular O2 probes, several different cell types and treatments including mitochondrial uncoupling and inhibition, depletion of extracellular Ca(2+) and inhibition of V-ATPase and histone deacetylases. The results show that compared to the standard microwell plates currently used, the μ-slide platform provides facile O2 measurements with both suspension and adherent cells, higher sensitivity and reproducibility, and faster measurement time. It also allows re-perfusion and multiple treatments of cells and multi-parametric analyses in conjunction with other probes. Optical measurements are conducted on standard fluorescence readers and microscopes.

Membraneless glucose/oxygen enzymatic fuel cells using redox hydrogel films containing carbon nanotubes.

PubMed

MacAodha, Domhnall; Ó Conghaile, Peter; Egan, Brenda; Kavanagh, Paul; Leech, Dónal

2013-07-22

Co-immobilisation of three separate multiple blue copper oxygenases, a Myceliophthora thermophila laccase, a Streptomyces coelicolor laccase and a Myrothecium verrucaria bilirubin oxidase, with an [Os(2,2'-bipyridine)2 (polyvinylimidazole)10Cl](+/2+) redox polymer in the presence of multi-walled carbon nanotubes (MWCNTs) on graphite electrodes results in enzyme electrodes that produce current densities above 0.5 mA cm(-2) for oxygen reduction at an applied potential of 0 V versus Ag/AgCl. Fully enzymatic membraneless fuel cells are assembled with the oxygen-reducing enzyme electrodes connected to glucose-oxidising anodes based on co-immobilisation of glucose oxidase or a flavin adenine dinucleotide-dependent glucose dehydrogenase with an [Os(4,4'-dimethyl-2,2'-bipyridine)2(polyvinylimidazole)10Cl](+/2+) redox polymer in the presence of MWCNTs on graphite electrodes. These fuel cells can produce power densities of up to 145 μW cm(-2) on operation in pH 7.4 phosphate buffer solution at 37 °C containing 150 mM NaCl, 5 mM glucose and 0.12 mM O2. The fuel cells based on Myceliophthora thermophila laccase enzyme electrodes produce the highest power density if combined with glucose oxidase-based anodes. Although the maximum power density of a fuel cell of glucose dehydrogenase and Myceliophthora thermophila laccase enzyme electrodes decreases from 110 μW cm(-2) in buffer to 60 μW cm(-2) on testing in artificial plasma, it provides the highest power output reported to date for a fully enzymatic glucose-oxidising, oxygen-reducing fuel cell in artificial plasma. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Light-addressable measurements of cellular oxygen consumption rates in microwell arrays based on phase-based phosphorescence lifetime detection

PubMed Central

Huang, Shih-Hao; Hsu, Yu-Hsuan; Wu, Chih-Wei; Wu, Chang-Jer

2012-01-01

A digital light modulation system that utilizes a modified commercial digital micromirror device (DMD) projector, which is equipped with a UV light-emitting diode as a light modulation source, has been developed to spatially direct excited light toward a microwell array device to detect the oxygen consumption rate (OCR) of single cells via phase-based phosphorescence lifetime detection. The microwell array device is composed of a combination of two components: an array of glass microwells containing Pt(II) octaethylporphine (PtOEP) as the oxygen-sensitive luminescent layer and a microfluidic module with pneumatically actuated glass lids set above the microwells to controllably seal the microwells of interest. By controlling the illumination pattern on the DMD, the modulated excitation light can be spatially projected to only excite the sealed microwell for cellular OCR measurements. The OCR of baby hamster kidney-21 fibroblast cells cultivated on the PtOEP layer within a sealed microwell has been successfully measured at 104 ± 2.96 amol s−1 cell−1. Repeatable and consistent measurements indicate that the oxygen measurements did not adversely affect the physiological state of the measured cells. The OCR of the cells exhibited a good linear relationship with the diameter of the microwells, ranging from 400 to 1000 μm and containing approximately 480 to 1200 cells within a microwell. In addition, the OCR variation of single cells in situ infected by Dengue virus with a different multiplicity of infection was also successfully measured in real-time. This proposed platform provides the potential for a wide range of biological applications in cell-based biosensing, toxicology, and drug discovery. PMID:24348889

Function evaluation of asphalt mixture with industrially produced BOF slag aggregate.

PubMed

Zhao, Meiling; Wu, Shaopeng; Chen, Zongwu; Li, Chao

2016-07-04

Laboratory research suggested that basic oxygen furnace (BOF) slag-based asphalt mixture was a functional material. However, the BOF slag aggregate's quality was difficult to control when it was heavily used in entity engineering. The primary objective of this research was to evaluate the functional performances of asphalt mixture containing BOF slag coarse aggregate (BSCA), which was from an industrialized production line. Limestone mixture was a control group. The Marshall method was first adopted to design asphalt mixtures. The performances of limestone asphalt mixture and BOF slag asphalt mixture including fatigue failure resistance and moisture stability were then evaluated and compared. Results showed that the asphalt mixture containing BSCA possessed better durability, which meant the quality of BSCA from industrialized production lines was well controlled and this BSCA can be heavily used in entity engineering.

Advanced gas atomization production of oxide dispersion strengthened (ODS) Ni-base superalloys through process and solidification control

NASA Astrophysics Data System (ADS)

Meyer, John Louis Lamb

A novel gas atomization reaction synthesis (GARS) method was utilized to produce precursor Ni-Cr-Y-Ti powder with a surface oxide and an internal rare earth (RE)-containing intermetallic. Although Al is necessary for industrial superalloy production, the Ni-Cr base alloy system was selected as a simplified system more amenable to characterization. This was done in an effort to better study the effects of processing parameters. Consolidation and heat-treatment were performed to promote the exchange of oxygen from the surface oxide to the RE intermetallic to form nanometric oxide dispersoids. Alloy selection was aided by an internal oxidation and serial grinding experiment that found that Hf-containing alloys may form more stable dispersoids than Ti-containing alloys, but the Hf-containing system exhibited five different oxide phases and two different intermetallics compared to the two oxide phases and one intermetallic in the Ti-containing alloys. Since the simpler Ti-containing system was easier to characterize, and make observations on the effects of processing parameters, the Ti-containing system was used for experimental atomization trials. An internal oxidation model was used to predict the heat treatment times necessary for dispersoid formation as a function of powder size and temperature. A new high-pressure gas atomization (HPGA) nozzle was developed with the aim of promoting fine powder production at scales similar to that of the high gas-flow and melt-flow of industrial atomizers. The atomization nozzle was characterized using schlieren imaging and aspiration pressure testing to determine the optimum melt delivery tip geometry and atomization pressure to promote enhanced secondary atomization mechanisms. Six atomization trials were performed to investigate the effects of gas atomization pressure and reactive-gas concentration on the particle size distribution (PSD). Also, the effect on the rapidly solidified microstructure (as a function of powder size) was investigated as a function of reactive-gas composition and bulk alloy composition. The results indicate that the pulsation mechanism and optimum PSDs reported in the literature were not observed. Also, it was determined that reactive gas may marginally improve the PSD, but further experiments are required. The oxygen content in the gas was also not found to be detrimental to the microstructure (i.e., did not catalyze nucleation), but may have removed potent catalytic nucleation sites, although not enough to significantly alter the microstructure. Overall, the downstream injection of oxygen was not found to significantly affect either the PSD or undercooling (as inferred from microstructure and XRD observations), but injection further upstream, including in the gas atomization nozzle, remains to be investigated.

Singlet oxygen signatures are detected independent of light or chloroplasts in response to multiple stresses.

PubMed

Mor, Avishai; Koh, Eugene; Weiner, Lev; Rosenwasser, Shilo; Sibony-Benyamini, Hadas; Fluhr, Robert

2014-05-01

The production of singlet oxygen is typically associated with inefficient dissipation of photosynthetic energy or can arise from light reactions as a result of accumulation of chlorophyll precursors as observed in fluorescent (flu)-like mutants. Such photodynamic production of singlet oxygen is thought to be involved in stress signaling and programmed cell death. Here we show that transcriptomes of multiple stresses, whether from light or dark treatments, were correlated with the transcriptome of the flu mutant. A core gene set of 118 genes, common to singlet oxygen, biotic and abiotic stresses was defined and confirmed to be activated photodynamically by the photosensitizer Rose Bengal. In addition, induction of the core gene set by abiotic and biotic selected stresses was shown to occur in the dark and in nonphotosynthetic tissue. Furthermore, when subjected to various biotic and abiotic stresses in the dark, the singlet oxygen-specific probe Singlet Oxygen Sensor Green detected rapid production of singlet oxygen in the Arabidopsis (Arabidopsis thaliana) root. Subcellular localization of Singlet Oxygen Sensor Green fluorescence showed its accumulation in mitochondria, peroxisomes, and the nucleus, suggesting several compartments as the possible origins or targets for singlet oxygen. Collectively, the results show that singlet oxygen can be produced by multiple stress pathways and can emanate from compartments other than the chloroplast in a light-independent manner. The results imply that the role of singlet oxygen in plant stress regulation and response is more ubiquitous than previously thought.

Singlet Oxygen Signatures Are Detected Independent of Light or Chloroplasts in Response to Multiple Stresses1[C][W

PubMed Central

Mor, Avishai; Koh, Eugene; Weiner, Lev; Rosenwasser, Shilo; Sibony-Benyamini, Hadas; Fluhr, Robert

2014-01-01

The production of singlet oxygen is typically associated with inefficient dissipation of photosynthetic energy or can arise from light reactions as a result of accumulation of chlorophyll precursors as observed in fluorescent (flu)-like mutants. Such photodynamic production of singlet oxygen is thought to be involved in stress signaling and programmed cell death. Here we show that transcriptomes of multiple stresses, whether from light or dark treatments, were correlated with the transcriptome of the flu mutant. A core gene set of 118 genes, common to singlet oxygen, biotic and abiotic stresses was defined and confirmed to be activated photodynamically by the photosensitizer Rose Bengal. In addition, induction of the core gene set by abiotic and biotic selected stresses was shown to occur in the dark and in nonphotosynthetic tissue. Furthermore, when subjected to various biotic and abiotic stresses in the dark, the singlet oxygen-specific probe Singlet Oxygen Sensor Green detected rapid production of singlet oxygen in the Arabidopsis (Arabidopsis thaliana) root. Subcellular localization of Singlet Oxygen Sensor Green fluorescence showed its accumulation in mitochondria, peroxisomes, and the nucleus, suggesting several compartments as the possible origins or targets for singlet oxygen. Collectively, the results show that singlet oxygen can be produced by multiple stress pathways and can emanate from compartments other than the chloroplast in a light-independent manner. The results imply that the role of singlet oxygen in plant stress regulation and response is more ubiquitous than previously thought. PMID:24599491

A Comparison Between Plant Photosystem I and Photosystem II Architecture and Functioning

PubMed Central

Caffarri, Stefano; Tibiletti, Tania; Jennings, Robert C.; Santabarbara, Stefano

2014-01-01

Oxygenic photosynthesis is indispensable both for the development and maintenance of life on earth by converting light energy into chemical energy and by producing molecular oxygen and consuming carbon dioxide. This latter process has been responsible for reducing the CO2 from its very high levels in the primitive atmosphere to the present low levels and thus reducing global temperatures to levels conducive to the development of life. Photosystem I and photosystem II are the two multi-protein complexes that contain the pigments necessary to harvest photons and use light energy to catalyse the primary photosynthetic endergonic reactions producing high energy compounds. Both photosystems are highly organised membrane supercomplexes composed of a core complex, containing the reaction centre where electron transport is initiated, and of a peripheral antenna system, which is important for light harvesting and photosynthetic activity regulation. If on the one hand both the chemical reactions catalysed by the two photosystems and their detailed structure are different, on the other hand they share many similarities. In this review we discuss and compare various aspects of the organisation, functioning and regulation of plant photosystems by comparing them for similarities and differences as obtained by structural, biochemical and spectroscopic investigations. PMID:24678674

A Novel Study of Methane-Rich Gas Reforming to Syngas and Its Kinetics over Semicoke Catalyst

PubMed Central

Zhang, Guojie; Su, Aiting; Qu, Jiangwen; Du, Yannian

2014-01-01

A small-size gasification unit is improved through process optimization to simulate industrial United Gas Improvement Company gasification. It finds that the reaction temperature has important impacts on semicoke catalyzed methane gas mixture. The addition of water vapor can enhance the catalytic activity of reforming, which is due to the fact that addition of water vapor not only removes carbon deposit produced in the reforming and gasification reaction processes, but also participates in gasification reaction with semicoke to generate some active oxygen-containing functional groups. The active oxygen-containing functional groups provide active sites for carbon dioxide reforming of methane, promoting the reforming reaction. It also finds that the addition of different proportions of methane-rich gas can yield synthesis gas with different H2/CO ratio. The kinetics study shows that the semicoke can reduce the activation energy of the reforming reaction and promote the occurrence of the reforming reaction. The kinetics model of methane reforming under the conditions of steam gasification over semicoke is as follows: k-=5.02×103·pCH40.71·pH20.26·exp(−74200/RT). PMID:24959620

Electrochemical oxygen reduction catalysed by Ni3(hexaiminotriphenylene)2.

PubMed

Miner, Elise M; Fukushima, Tomohiro; Sheberla, Dennis; Sun, Lei; Surendranath, Yogesh; Dincă, Mircea

2016-03-08

Control over the architectural and electronic properties of heterogeneous catalysts poses a major obstacle in the targeted design of active and stable non-platinum group metal electrocatalysts for the oxygen reduction reaction. Here we introduce Ni3(HITP)2 (HITP=2, 3, 6, 7, 10, 11-hexaiminotriphenylene) as an intrinsically conductive metal-organic framework which functions as a well-defined, tunable oxygen reduction electrocatalyst in alkaline solution. Ni3(HITP)2 exhibits oxygen reduction activity competitive with the most active non-platinum group metal electrocatalysts and stability during extended polarization. The square planar Ni-N4 sites are structurally reminiscent of the highly active and widely studied non-platinum group metal electrocatalysts containing M-N4 units. Ni3(HITP)2 and analogues thereof combine the high crystallinity of metal-organic frameworks, the physical durability and electrical conductivity of graphitic materials, and the diverse yet well-controlled synthetic accessibility of molecular species. Such properties may enable the targeted synthesis and systematic optimization of oxygen reduction electrocatalysts as components of fuel cells and electrolysers for renewable energy applications.

Electrochemical oxygen reduction catalysed by Ni3(hexaiminotriphenylene)2

PubMed Central

Miner, Elise M.; Fukushima, Tomohiro; Sheberla, Dennis; Sun, Lei; Surendranath, Yogesh; Dincă, Mircea

2016-01-01

Control over the architectural and electronic properties of heterogeneous catalysts poses a major obstacle in the targeted design of active and stable non-platinum group metal electrocatalysts for the oxygen reduction reaction. Here we introduce Ni3(HITP)2 (HITP=2, 3, 6, 7, 10, 11-hexaiminotriphenylene) as an intrinsically conductive metal-organic framework which functions as a well-defined, tunable oxygen reduction electrocatalyst in alkaline solution. Ni3(HITP)2 exhibits oxygen reduction activity competitive with the most active non-platinum group metal electrocatalysts and stability during extended polarization. The square planar Ni-N4 sites are structurally reminiscent of the highly active and widely studied non-platinum group metal electrocatalysts containing M-N4 units. Ni3(HITP)2 and analogues thereof combine the high crystallinity of metal-organic frameworks, the physical durability and electrical conductivity of graphitic materials, and the diverse yet well-controlled synthetic accessibility of molecular species. Such properties may enable the targeted synthesis and systematic optimization of oxygen reduction electrocatalysts as components of fuel cells and electrolysers for renewable energy applications. PMID:26952523

Electrochemical oxygen reduction catalysed by Ni 3(hexaiminotriphenylene) 2

DOE PAGES

Miner, Elise M.; Fukushima, Tomohiro; Sheberla, Dennis; ...

2016-03-08

Control over the architectural and electronic properties of heterogeneous catalysts poses a major obstacle in the targeted design of active and stable non-platinum group metal electrocatalysts for the oxygen reduction reaction. Here we introduce Ni 3(HITP) 2 (HITP=2, 3, 6, 7, 10, 11-hexaiminotriphenylene) as an intrinsically conductive metal-organic framework which functions as a well-defined, tunable oxygen reduction electrocatalyst in alkaline solution. Ni 3(HITP) 2 exhibits oxygen reduction activity competitive with the most active non-platinum group metal electrocatalysts and stability during extended polarization. The square planar Ni-N 4 sites are structurally reminiscent of the highly active and widely studied non-platinum groupmore » metal electrocatalysts containing M-N 4 units. Ni 3(HITP) 2 and analogues thereof combine the high crystallinity of metal-organic frameworks, the physical durability and electrical conductivity of graphitic materials, and the diverse yet well-controlled synthetic accessibility of molecular species. As a result, such properties may enable the targeted synthesis and systematic optimization of oxygen reduction electrocatalysts as components of fuel cells and electrolysers for renewable energy applications.« less

Fabrication of nanocapsule carriers from multilayer-coated vaterite calcium carbonate nanoparticles.

PubMed

Biswas, Aniket; Nagaraja, Ashvin T; McShane, Michael J

2014-12-10

Nanosized luminescent sensors were prepared as reagents for optical sensing and imaging of oxygen using ratiometric emission properties of a two-dye system. Polymeric capsules were fabricated utilizing poly(vinylsulfonic acid) (PVSA)-stabilized vaterite CaCO3 nanoparticles (CCNPs) as sacrificial templates. The buffer and polymeric surfactant requirements of the layer-by-layer (LbL) process were evaluated toward deposition of multilayer coatings and, ultimately, formation of hollow capsules using these interesting materials. CCNPs were found to be more stable in alkaline NaHCO3 buffer after repeated cycles of washing under sonication and resuspension. An intermediate PVSA concentration was required to maximize the loading of oxygen-sensitive porphyrin and oxygen-insensitive fluorescent nanoparticles in the CCNPs while maintaining minimal nanoparticle size. The CCNPs were then coated with polyelectrolyte multilayers and subsequent removal of the CaCO3 core yielded nanocapsules containing dye and fluorescent nanoparticles. The resulting nanocapsules with encapsulated luminophores functioned effectively as oxygen sensors with a quenching response of 89.28 ± 2.59%, and O2 (S = 1/2) = 20.91 μM of dissolved oxygen.

Water dynamics on ice and hydrate lattices studied by second-order central-line stimulated-echo oxygen-17 nuclear magnetic resonance

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

Adjei-Acheamfour, Mischa; Tilly, Julius F.; Beerwerth, Joachim

Oxygen-17 stimulated-echo spectroscopy is a novel nuclear magnetic resonance (NMR) technique that allows one to investigate the time scale and geometry of ultraslow molecular motions in materials containing oxygen. The method is based on detecting orientationally encoded frequency changes within oxygen’s central-transition NMR line that are caused by second-order quadrupolar interactions. In addition to the latter, the present theoretical analysis of various two-pulse echo and stimulated-echo pulse sequences takes also heteronuclear dipolar interactions into account. As an experimental example, the ultraslow water motion in polycrystals of tetrahydrofuran clathrate hydrate is studied via two-time oxygen-17 stimulated-echo correlation functions. The resulting correlationmore » times and those of hexagonal ice are similar to those from previous deuteron NMR measurements. Calculations of the echo functions’ final-state correlations for various motional models are compared with the experimental data of the clathrate hydrate. It is found that a six-site model including the oxygen-proton dipolar interaction describes the present results.« less

Plastron Respiration Using Commercial Fabrics

PubMed Central

Atherton, Shaun; Brennan, Joseph C.; Morris, Robert H.; Smith, Joshua D.E.; Hamlett, Christopher A.E.; McHale, Glen; Shirtcliffe, Neil J.; Newton, Michael I.

2014-01-01

A variety of insect and arachnid species are able to remain submerged in water indefinitely using plastron respiration. A plastron is a surface-retained film of air produced by surface morphology that acts as an oxygen-carbon dioxide exchange surface. Many highly water repellent and hydrophobic surfaces when placed in water exhibit a silvery sheen which is characteristic of a plastron. In this article, the hydrophobicity of a range of commercially available water repellent fabrics and polymer membranes is investigated, and how the surface of the materials mimics this mechanism of underwater respiration is demonstrated allowing direct extraction of oxygen from oxygenated water. The coverage of the surface with the plastron air layer was measured using confocal microscopy. A zinc/oxygen cell is used to consume oxygen within containers constructed from the different membranes, and the oxygen consumed by the cell is compared to the change in oxygen concentration as measured by an oxygen probe. By comparing the membranes to an air-tight reference sample, it was found that the membranes facilitated oxygen transfer from the water into the container, with the most successful membrane showing a 1.90:1 ratio between the cell oxygen consumption and the change in concentration within the container. PMID:28788469

Thermochemical Properties of the Lattice Oxygen in W,Mn-Containing Mixed Oxide Catalysts for the Oxidative Coupling of Methane

NASA Astrophysics Data System (ADS)

Lomonosov, V. I.; Gordienko, Yu. A.; Sinev, M. Yu.; Rogov, V. A.; Sadykov, V. A.

2018-03-01

Mixed NaWMn/SiO2 oxide, samples containing individual components (Na, W, Mn) and their double combinations (Na-W, Na-Mn, W-Mn) supported on silica were studied by temperature programmed reduction (TPR) and desorption (TPD), and heat flow calorimetry during their reoxidation with molecular oxygen in pulse mode. The NaWMn/SiO2 mixed oxide was shown to contain two different types of reactive lattice oxygen. The weakly-bonded oxygen can be reversibly released from the oxide in a flow of inert gas in the temperature range of 575‒900°C, while the strongly-bonded oxygen can be removed during the reduction of the sample with hydrogen at 700-900°C. The measured thermal effect of oxygen consumption for these two oxygen forms are 185 and 350 kJ/mol, respectively. The amount of oxygen removed at reduction ( 443 μmol/g) considerably exceeded the amount desorbed in an inert gas flow ( 56 μmol/g). The obtained results suggest that the reversible oxygen desorption is due to the redox process in which manganese ions are involved, while during the temperature programmed reduction, mainly oxygen bonded with tungsten is removed.

Charge storage in oxygen deficient phases of TiO2: defect Physics without defects.

PubMed

Padilha, A C M; Raebiger, H; Rocha, A R; Dalpian, G M

2016-07-01

Defects in semiconductors can exhibit multiple charge states, which can be used for charge storage applications. Here we consider such charge storage in a series of oxygen deficient phases of TiO2, known as Magnéli phases. These Magnéli phases (TinO2n-1) present well-defined crystalline structures, i.e., their deviation from stoichiometry is accommodated by changes in space group as opposed to point defects. We show that these phases exhibit intermediate bands with an electronic quadruple donor transitions akin to interstitial Ti defect levels in rutile TiO2. Thus, the Magnéli phases behave as if they contained a very large pseudo-defect density: ½ per formula unit TinO2n-1. Depending on the Fermi Energy the whole material will become charged. These crystals are natural charge storage materials with a storage capacity that rivals the best known supercapacitors.

Three-dimensional functional magnetic resonance imaging of human brain on a clinical 1.5-T scanner.

PubMed Central

van Gelderen, P; Ramsey, N F; Liu, G; Duyn, J H; Frank, J A; Weinberger, D R; Moonen, C T

1995-01-01

Functional magnetic resonance imaging (fMRI) is a tool for mapping brain function that utilizes neuronal activity-induced changes in blood oxygenation. An efficient three-dimensional fMRI method is presented for imaging brain activity on conventional, widely available, 1.5-T scanners, without additional hardware. This approach uses large magnetic susceptibility weighting based on the echo-shifting principle combined with multiple gradient echoes per excitation. Motor stimulation, induced by self-paced finger tapping, reliably produced significant signal increase in the hand region of the contralateral primary motor cortex in every subject tested. Images Fig. 2 Fig. 3 PMID:7624341

Amine oxidation by d-arginine dehydrogenase in Pseudomonas aeruginosa.

PubMed

Ouedraogo, Daniel; Ball, Jacob; Iyer, Archana; Reis, Renata A G; Vodovoz, Maria; Gadda, Giovanni

2017-10-15

d-Arginine dehydrogenase from Pseudomonas aeruginosa (PaDADH) is a flavin-dependent oxidoreductase, which is part of a novel two-enzyme racemization system that functions to convert d-arginine to l-arginine. PaDADH contains a noncovalently linked FAD that shows the highest activity with d-arginine. The enzyme exhibits broad substrate specificity towards d-amino acids, particularly with cationic and hydrophobic d-amino acids. Biochemical studies have established the structure and the mechanistic properties of the enzyme. The enzyme is a true dehydrogenase because it displays no reactivity towards molecular oxygen. As established through solvent and multiple kinetic isotope studies, PaDADH catalyzes an asynchronous CH and NH bond cleavage via a hydride transfer mechanism. Steady-state kinetic studies with d-arginine and d-histidine are consistent with the enzyme following a ping-pong bi-bi mechanism. As shown by a combination of crystallography, kinetic and computational data, the shape and flexibility of loop L1 in the active site of PaDADH are important for substrate capture and broad substrate specificity. Copyright © 2017 Elsevier Inc. All rights reserved.

The change of longitudinal relaxation rate in oxygen enhanced pulmonary MRI depends on age and BMI but not diffusing capacity of carbon monoxide in healthy never-smokers.

PubMed

Kindvall, Simon Sven Ivan; Diaz, Sandra; Svensson, Jonas; Wollmer, Per; Olsson, Lars E

2017-01-01

Oxygen enhanced pulmonary MRI is a promising modality for functional lung studies and has been applied to a wide range of pulmonary conditions. The purpose of this study was to characterize the oxygen enhancement effect in the lungs of healthy, never-smokers, in light of a previously established relationship between oxygen enhancement and diffusing capacity of carbon monoxide in the lung (DL,CO) in patients with lung disease. In 30 healthy never-smoking volunteers, an inversion recovery with gradient echo read-out (Snapshot-FLASH) was used to quantify the difference in longitudinal relaxation rate, while breathing air and 100% oxygen, ΔR1, at 1.5 Tesla. Measurements were performed under multiple tidal inspiration breath-holds. In single parameter linear models, ΔR1 exhibit a significant correlation with age (p = 0.003) and BMI (p = 0.0004), but not DL,CO (p = 0.33). Stepwise linear regression of ΔR1 yields an optimized model including an age-BMI interaction term. In this healthy, never-smoking cohort, age and BMI are both predictors of the change in MRI longitudinal relaxation rate when breathing oxygen. However, DL,CO does not show a significant correlation with the oxygen enhancement. This is possibly because oxygen transfer in the lung is not diffusion limited at rest in healthy individuals. This work stresses the importance of using a physiological model to understand results from oxygen enhanced MRI.

Inactivation of bacteria by a mixed argon and oxygen micro-plasma as a function of exposure time.

PubMed

Weng, Chih-Chiang; Wu, Yi-Te; Liao, Juinn-Der; Kao, Chi-Yuan; Chao, Chih-Cheng; Chang, Juu-En; Hsu, Bo-Wen

2009-04-01

A radio-frequency dielectric barrier discharge (DBD) was applied as a micro-plasma device for the inactivation of bacteria, e.g., Escherichia coli. The cultured bacteria were placed on a polydimethyl siloxane (PDMS) film and placed inside the DBD cavity. The bacteria were exposed to micro-plasmas of varying oxygen/argon ratios for different exposure times. The survival of the bacteria was measured by determining bacterial growth using optical methods. The excited oxygen species increased with the increase in the oxygen to argon ratio as measured by optical emission spectroscopy (OES), but the increase of excited oxygen species in argon micro-plasma did not enhance the inactivation of bacteria. In contrast, increases in the time the bacteria were exposed to the micro-plasma were of importance. The results show that a continuous plasma flow containing energetic and reactive species may result in electro-physical interactions with bacteria exposed to the plasma leading to their inactivation. For currently-employed DBD device, addition of 0.5% oxygen to the argon micro-plasma for an exposure time of 30 sec was optimum for the inactivation of E. coli.

Promiscuous anaerobes: new and unconventional metabolism in methanogenic archaea.

PubMed

Grochowski, Laura L; White, Robert H

2008-03-01

The development of an oxygenated atmosphere on earth resulted in the polarization of life into two major groups, those that could live in the presence of oxygen and those that could not-the aerobes and the anaerobes. The evolution of aerobes from the earliest anaerobic prokaryotes resulted in a variety of metabolic adaptations. Many of these adaptations center on the need to sustain oxygen-sensitive reactions and cofactors to function in the new oxygen-containing atmosphere. Still other metabolic pathways that were not sensitive to oxygen also diverged. This is likely due to the physical separation of the organisms, based on their ability to live in the presence of oxygen, which allowed for the independent evolution of the pathways. Through the study of metabolic pathways in anaerobes and comparison to the more established pathways from aerobes, insight into metabolic evolution can be gained. This, in turn, can allow for extra- polation to those metabolic pathways occurring in the Last Universal Common Ancestor (LUCA). Some of the unique and uncanonical metabolic pathways that have been identified in the archaea with emphasis on the biochemistry of an obligate anaerobic methanogen, Methanocaldococcus jannaschii are reviewed.

Structural requirements and reaction pathways in dimethyl ether combustion catalyzed by supported Pt clusters.

PubMed

Ishikawa, Akio; Neurock, Matthew; Iglesia, Enrique

2007-10-31

The identity and reversibility of the elementary steps required for catalytic combustion of dimethyl ether (DME) on Pt clusters were determined by combining isotopic and kinetic analyses with density functional theory estimates of reaction energies and activation barriers to probe the lowest energy paths. Reaction rates are limited by C-H bond activation in DME molecules adsorbed on surfaces of Pt clusters containing chemisorbed oxygen atoms at near-saturation coverages. Reaction energies and activation barriers for C-H bond activation in DME to form methoxymethyl and hydroxyl surface intermediates show that this step is more favorable than the activation of C-O bonds to form two methoxides, consistent with measured rates and kinetic isotope effects. This kinetic preference is driven by the greater stability of the CH3OCH2* and OH* intermediates relative to chemisorbed methoxides. Experimental activation barriers on Pt clusters agree with density functional theory (DFT)-derived barriers on oxygen-covered Pt(111). Measured DME turnover rates increased with increasing DME pressure, but decreased as the O2 pressure increased, because vacancies (*) on Pt surfaces nearly saturated with chemisorbed oxygen are required for DME chemisorption. DFT calculations show that although these surface vacancies are required, higher oxygen coverages lead to lower C-H activation barriers, because the basicity of oxygen adatoms increases with coverage and they become more effective in hydrogen abstraction from DME. Water inhibits reaction rates via quasi-equilibrated adsorption on vacancy sites, consistent with DFT results indicating that water binds more strongly than DME on vacancies. These conclusions are consistent with the measured kinetic response of combustion rates to DME, O2, and H2O, with H/D kinetic isotope effects, and with the absence of isotopic scrambling in reactants containing isotopic mixtures of 18O2-16O2 or 12CH3O12CH3-13CH3O13CH3. Turnover rates increased with Pt cluster size, because small clusters, with more coordinatively unsaturated surface atoms, bind oxygen atoms more strongly than larger clusters and exhibit lower steady-state vacancy concentrations and a consequently smaller number of adsorbed DME intermediates involved in kinetically relevant steps. These effects of cluster size and metal-oxygen bond energies on reactivity are ubiquitous in oxidation reactions requiring vacancies on surfaces nearly saturated with intermediates derived from O2.

Shedding Light on the Oxygen Reduction Reaction Mechanism in Ether-Based Electrolyte Solutions: A Study Using Operando UV-Vis Spectroscopy.

PubMed

Hirshberg, Daniel; Sharon, Daniel; Afri, Michal; Lavi, Ronit; Frimer, Aryeh A; Metoki, Noa; Eliaz, Noam; Kwak, Won-Jin; Sun, Yang-Kook; Aurbach, Doron

2018-04-04

Using UV-vis spectroscopy in conjunction with various electrochemical techniques, we have developed a new effective operando methodology for investigating the oxygen reduction reactions (ORRs) and their mechanisms in nonaqueous solutions. We can follow the in situ formation and presence of superoxide moieties during ORR as a function of solvent, cations, anions, and additives in the solution. Thus, using operando UV-vis spectroscopy, we found evidence for the formation of superoxide radical anions during oxygen reduction in LiTFSI/diglyme electrolyte solutions. Nitro blue tetrazolium (NBT) was used to indicate the presence of superoxide moieties based on its unique spectral response. Indeed, the spectral response of NBT containing solutions undergoing ORR could provide a direct indication for the level of association of the Li cations with the electrolyte anions.

Habitat characteristics of larval mosquitoes in zoos of South Carolina, USA.

PubMed

Tuten, Holly C

2011-06-01

To investigate whether the unique assemblage of habitats in zoos could affect mosquito oviposition behavior and to provide zoos with suggestions for mosquito control, larvae were sampled and associated habitat variables were measured in 2 zoos in South Carolina, U.S.A. Fifty-nine sites were sampled from March 2008 to January 2009. A total of 1630 larvae representing 16 species was collected and identified. The dominant species was Aedes albopictus (46.0%), followed by Ae. triseriatus (23.6%), Culex restuans (12.4%), and Cx. pipiens complex (9.7%). Principal components and multiple logistic regression analyses showed that across both zoos the distribution of Ae. albopictus larvae was predicted by ambient and site temperature, precipitation, dissolved oxygen, and container habitats. The distribution of Ae. triseriatus larvae was predicted by natural containers and shade height < or =2 m. Overall larval mosquito presence (regardless of species) was predicted by ambient and site temperature, precipitation, dissolved oxygen, presence of natural habitats, and absence of aquatic vegetation. Additionally, C8 values of pairwise species associations indicated significant habitat-based relationships between Ae. albopictus and Ae. triseriatus, and Cx. pipiens complex and Cx. restuans. In general, species-habitat associations conformed to previously published studies. Recommendations to zoo personnel include elimination of artificial container habitats, reduction of shade sources < or =2 m over aquatic habitats, use of approved mosquito larvicides, and training in recognizing and mitigating larval mosquito habitats.

[Hemoglobin, from microorganisms to man: a single structural motif, multiple functions].

PubMed

Wajcman, Henri; Kiger, Laurent

2002-12-01

Haemoglobins from unicellular organisms, plants or animals, share a common structure, which results from the folding, around the heme group, of a polypeptide chain made from 6-8 helices. Nowadays, deciphering the genome of several species allows one to draw the evolutionary tree of this protein going back to 1800 millions of years, at a time when oxygen began to accumulate in the atmosphere. This permits to follow the evolution of the ancestral gene and of its product. It is likely that, only in complex multicellular species, transport and storage of oxygen became the main physiological function of this molecule. In addition, in unicellular organisms and small invertebrates, it is likely that the main function of this protein was to protect the organism from the toxic effect of O2, CO and NO*. The very high oxygen affinity of these molecules, leading them to act rather as a scavenger as an oxygen carrier, supports this hypothesis. Haemoglobins from microorganisms, which may probably be the closest vestiges to the ancestral molecules, are divided into three families. The first one is made from flavohaemoglobins, a group of chimerical proteins carrying a globin domain and an oxido-reduction FAD-dependant domain. The second corresponds to truncated haemoglobins, which are hexacoordinated with very high oxygen-affinity molecules, 20-40 residues shorter than classical haemoglobins. The third group is made from bacterial haemoglobins such as that of Vitreoscilla. Some specific structural arrangements in the region surrounding the heme are cause of their high oxygen affinity. In plants, two types of haemoglobins are present (non-symbiotic and symbiotic), that arose from duplication of an ancestral vegetal gene. Non-symbiotic haemoglobins, which are probably the oldest, are scarcely distributed within tissues having high energetic consumption. Conversely, symbiotic haemoglobins (also named leghaemoglobins) are present at a high concentration (mM) mostly in the rhizomes of legumes, where they are involved in nitrogen metabolism. In some species, haemoglobin was proposed to be an oxygen sensor bringing to the organism information to adjust metabolism or biosynthesis to the oxygen requirement. Elsewhere haemoglobin may act as final electron acceptors in oxido-reduction pathways. Evolution of haemoglobin in invertebrates followed a large variety of scenarios. Some surprising functions as sulphide acquisition in invertebrates living near hydrothermal vents, or a role in the phototrophism of worm need to be mentioned. In invertebrates, the size of haemoglobin varies from monomers to giant molecules associating up to 144 subunits, while in vertebrates it is always a tetramer. In some species, several haemoglobins, with completely different structure and function, may coexist. This demonstrates how hazardous may be to extrapolate the function of a protein from only structural data.

Oxygen distribution and aerobic respiration in the north and south eastern tropical Pacific oxygen minimum zones

NASA Astrophysics Data System (ADS)

Tiano, Laura; Garcia-Robledo, Emilio; Dalsgaard, Tage; Devol, Allan H.; Ward, Bess B.; Ulloa, Osvaldo; Canfield, Donald E.; Peter Revsbech, Niels

2014-12-01

Highly sensitive STOX O2 sensors were used for determination of in situ O2 distribution in the eastern tropical north and south Pacific oxygen minimum zones (ETN/SP OMZs), as well as for laboratory determination of O2 uptake rates of water masses at various depths within these OMZs. Oxygen was generally below the detection limit (few nmol L-1) in the core of both OMZs, suggesting the presence of vast volumes of functionally anoxic waters in the eastern Pacific Ocean. Oxygen was often not detectable in the deep secondary chlorophyll maximum found at some locations, but other secondary maxima contained up to 0.4 μmol L-1. Directly measured respiration rates were high in surface and subsurface oxic layers of the coastal waters, reaching values up to 85 nmol L-1 O2 h-1. Substantially lower values were found at the depths of the upper oxycline, where values varied from 2 to 33 nmol L-1 O2 h-1. Where secondary chlorophyll maxima were found the rates were higher than in the oxic water just above. Incubation times longer than 20 h, in the all-glass containers, resulted in highly increased respiration rates. Addition of amino acids to the water from the upper oxycline did not lead to a significant initial rise in respiration rate within the first 20 h, indicating that the measurement of respiration rates in oligotrophic Ocean water may not be severely affected by low levels of organic contamination during sampling. Our measurements indicate that aerobic metabolism proceeds efficiently at extremely low oxygen concentrations with apparent half-saturation concentrations (Km values) ranging from about 10 to about 200 nmol L-1.

Crystallization and preliminary X-ray crystallographic study of a 3.8-MDa respiratory supermolecule hemocyanin.

PubMed

Matsuno, Asuka; Gai, Zuoqi; Tanaka, Miyuki; Kato, Koji; Kato, Sanae; Katoh, Tsuyoshi; Shimizu, Takeshi; Yoshioka, Takeya; Kishimura, Hideki; Tanaka, Yoshikazu; Yao, Min

2015-06-01

Many molluscs transport oxygen using a very large cylindrical multimeric copper-containing protein named hemocyanin. The molluscan hemocyanin forms a decamer (cephalopods) or multidecamer (gastropods) of approximately 330-450kDa subunits, resulting in a molecular mass >3.3MDa. Therefore, molluscan hemocyanin is one of the largest proteins. The reason why these organisms use such a large supermolecule for oxygen transport remains unclear. Atomic-resolution X-ray crystallographic analysis is necessary to unveil the detailed molecular structure of this mysterious large molecule. However, its propensity to dissociate in solution has hampered the crystallization of its intact form. In the present study, we successfully obtained the first crystals of an intact decameric molluscan hemocyanin. The diffraction dataset at 3.0-Å resolution was collected by merging the datasets of two isomorphic crystals. Electron microscopy analysis of the dissolved crystals revealed cylindrical particles. Furthermore, self-rotation function analysis clearly showed the presence of a fivefold symmetry with several twofold symmetries perpendicular to the fivefold axis. The absorption spectrum of the crystals showed an absorption peak around 345nm. These results indicated that the crystals contain intact hemocyanin decamers in the oxygen-bound form. Copyright © 2015 Elsevier Inc. All rights reserved.

How does spatial extent of fMRI datasets affect independent component analysis decomposition?

PubMed

Aragri, Adriana; Scarabino, Tommaso; Seifritz, Erich; Comani, Silvia; Cirillo, Sossio; Tedeschi, Gioacchino; Esposito, Fabrizio; Di Salle, Francesco

2006-09-01

Spatial independent component analysis (sICA) of functional magnetic resonance imaging (fMRI) time series can generate meaningful activation maps and associated descriptive signals, which are useful to evaluate datasets of the entire brain or selected portions of it. Besides computational implications, variations in the input dataset combined with the multivariate nature of ICA may lead to different spatial or temporal readouts of brain activation phenomena. By reducing and increasing a volume of interest (VOI), we applied sICA to different datasets from real activation experiments with multislice acquisition and single or multiple sensory-motor task-induced blood oxygenation level-dependent (BOLD) signal sources with different spatial and temporal structure. Using receiver operating characteristics (ROC) methodology for accuracy evaluation and multiple regression analysis as benchmark, we compared sICA decompositions of reduced and increased VOI fMRI time-series containing auditory, motor and hemifield visual activation occurring separately or simultaneously in time. Both approaches yielded valid results; however, the results of the increased VOI approach were spatially more accurate compared to the results of the decreased VOI approach. This is consistent with the capability of sICA to take advantage of extended samples of statistical observations and suggests that sICA is more powerful with extended rather than reduced VOI datasets to delineate brain activity. (c) 2006 Wiley-Liss, Inc.

Surface acoustic wave oxygen sensor

NASA Technical Reports Server (NTRS)

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

1994-01-01

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

Unilateral donor lung dysfunction does not preclude successful contralateral single lung transplantation.

PubMed

Puskas, J D; Winton, T L; Miller, J D; Scavuzzo, M; Patterson, G A

1992-05-01

Single lung transplantation remains limited by a severe shortage of suitable donor lungs. Potential lung donors are often deemed unsuitable because accepted criteria (both lungs clear on the chest roentgenogram, arterial oxygen tension greater than 300 mm Hg with an inspired oxygen fraction of 1.0, a positive end-expiratory pressure of 5 cm H2O, and no purulent secretions) do not distinguish between unilateral and bilateral pulmonary disease. Many adequate single lung grafts may be discarded as a result of contralateral aspiration or pulmonary trauma. We have recently used intraoperative unilateral ventilation and perfusion to assess single lung function in potential donors with contralateral lung disease. In the 11-month period ending October 1, 1990, we performed 18 single lung transplants. In four of these cases (22%), the donor chest roentgenogram or bronchoscopic examination demonstrated significant unilateral lung injury. Donor arterial oxygen tension, (inspired oxygen fraction 1.0; positive end-expiratory pressure 5 cm H2O) was below the accepted level in each case (246 +/- 47 mm Hg, mean +/- standard deviation). Through the sternotomy used for multiple organ harvest, the pulmonary artery to the injured lung was clamped. A double-lumen endotracheal tube or endobronchial balloon occlusion catheter was used to permit ventilation of the uninjured lung alone. A second measurement of arterial oxygen tension (inspired oxygen fraction 1.0; positive end-expiratory pressure 5 cm H2O) revealed excellent unilateral lung function in all four cases (499.5 +/- 43 mm Hg; p less than 0.0004). These single lung grafts (three right, one left) were transplanted uneventfully into four recipients (three with pulmonary fibrosis and one with primary pulmonary hypertension). Lung function early after transplantation was adequate in all patients. Two patients were extubated within 24 hours. There were two late deaths, one caused by rejection and Aspergillus infection and the other caused by cytomegalovirus 6 months after transplantation. Two patients are alive and doing well. We conclude that assessment of unilateral lung function in potential lung donors is indicated in selected cases, may be quickly and easily performed, and may significantly increase the availability of single lung grafts.

Analysis of Atmospheric Nitrate Deposition in Lake Tahoe Using Multiple Oxygen Isotopes

NASA Astrophysics Data System (ADS)

McCabe, J. R.; Michalski, G. M.; Hernandez, L. P.; Thiemens, M. H.; Taylor, K.; Kendall, C.; Wankel, S. D.

2002-12-01

Lake Tahoe in the Sierra Nevada Mountain Range is world renown for its depth and water clarity bringing 2.2 million visitors per year resulting in annual revenue of \\1.6 billion from tourism. In past decades the lake has suffered from decreased water clarity (from 32 m plate depth to less than 20), which is believed to be largely the result of algae growth initiated by increased nutrient loading. Lake nutrients have also seen a shift from a nitrogen limited to a phosphorous limited system indicating a large increase in the flux of fixed nitrogen. Several sources of fixed nitrogen of have been suggested including surface runoff, septic tank seepage from ground water and deposition from the atmosphere. Bio-available nitrogen in the form of nitrate (NO_{3}$-) is a main component of this system. Recent studies have estimated that approximately 50% of the nitrogen input into the lake is of atmospheric origin (Allison et al. 2000). However, the impact and magnitude of atmospheric deposition is still one of the least understood aspects of the relationship between air and water quality in the Basin (TRPA Threshold Assessment 2002). The utility of stable isotopes as tracers of nitrate reservoirs has been shown in several studies (Bohlke et al. 1997, Kendall and McDonnell 1998, Durka et al. 1994). Stable nitrogen (δ15N) and oxygen (δ18O) isotopes have been implemented in a dual isotope approach to characterize the various nitrate sources to an ecosystem. While δ18O distinguishes between atmospheric and soil sources of nitrate, processes such as denitrification can enrich the residual nitrate in δ18O leaving a misleading atmospheric signature. The benefit of δ15N as a tracer for NO3- sources is the ability to differentiate natural soil, fertilizer, and animal or septic waste, which contain equivalent δ18O values. The recent implementation of multiple oxygen isotopes to measure Δ17O in nitrate has proven to be a more sensitive tracer of atmospheric deposition. The oxygen isotopes of atmospheric nitrate are mass-independently fractionated and contain Δ17O values of 20 to 30 \\permil, while all other sources are mass dependent (Δ17O = 0 \\permil). Any subsequent fractionation of the atmospheric nitrate will leave the mass-independent signature unchanged making Δ17O of nitrate a conservative tracer of atmospheric nitrate. Results from measurements of the oxygen isotope composition of nitrate in Lake Tahoe are used to resolve the atmospheric contribution.

Comparative analysis of spatial organization of laccases from Cerrena maxima and Coriolus zonatus

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

Zhukova, Yu. N.; Zhukhlistova, N. E.; Lyashenko, A. V.

2007-09-15

Laccase (oxygen oxidoreductase, EC 1.10.3.2) belongs to the multicopper oxidase family. The main function of this enzyme is to perform electron transfer from the oxidized substrate through the mononuclear copper-containing site T1 to the oxygen molecule bound to the site T3 in the trinuclear T2/T3 cluster. The structures of two new fungal laccases from C. maxima and C. zonatus were solved on the basis of synchrotron X-ray diffraction data. Both laccases show high structural homology with laccases from other sources. The role of the carbohydrate component of laccases in structure stabilization and formation of ordered protein crystals was demonstrated. Inmore » the structures of C. maxima and C. zonatus laccases, two water channels of functional importance were found and characterized. The structural results reported in the present study characterize one of the functional states of the enzyme fixed in the crystal structure.« less

High electrochemical capacitor performance of oxygen and nitrogen enriched activated carbon derived from the pyrolysis and activation of squid gladius chitin

NASA Astrophysics Data System (ADS)

Raj, C. Justin; Rajesh, Murugesan; Manikandan, Ramu; Yu, Kook Hyun; Anusha, J. R.; Ahn, Jun Hwan; Kim, Dong-Won; Park, Sang Yeup; Kim, Byung Chul

2018-05-01

Activated carbon containing nitrogen functionalities exhibits excellent electrochemical property which is more interesting for several renewable energy storage and catalytic applications. Here, we report the synthesis of microporous oxygen and nitrogen doped activated carbon utilizing chitin from the gladius of squid fish. The activated carbon has large surface area of 1129 m2 g-1 with microporous network and possess ∼4.04% of nitrogen content in the form of pyridinic/pyrrolic-N, graphitic-N and N-oxide groups along with oxygen and carbon species. The microporous oxygen/nitrogen doped activated carbon is utilize for the fabrication of aqueous and flexible supercapacitor electrodes, which presents excellent electrochemical performance with maximum specific capacitance of 204 Fg-1 in 1 M H2SO4 electrolyte and 197 Fg-1 as a flexible supercapacitor. Moreover, the device displays 100% of specific capacitance retention after 25,000 subsequent charge/discharge cycles in 1 M H2SO4 electrolyte.

46 CFR 154.906 - Inert gas generators.

Code of Federal Regulations, 2012 CFR

2012-10-01

...: (a) Produce an inert gas containing less than 5% oxygen by volume; (b) Have a device to continuously sample the discharge of the generator for oxygen content; and (c) Have an audible and visual alarm in the cargo control station that alarms when the inert gas contains 5% or more oxygen by volume. ...

46 CFR 154.906 - Inert gas generators.

Code of Federal Regulations, 2014 CFR

2014-10-01

...: (a) Produce an inert gas containing less than 5% oxygen by volume; (b) Have a device to continuously sample the discharge of the generator for oxygen content; and (c) Have an audible and visual alarm in the cargo control station that alarms when the inert gas contains 5% or more oxygen by volume. ...

46 CFR 154.906 - Inert gas generators.

Code of Federal Regulations, 2013 CFR

2013-10-01

...: (a) Produce an inert gas containing less than 5% oxygen by volume; (b) Have a device to continuously sample the discharge of the generator for oxygen content; and (c) Have an audible and visual alarm in the cargo control station that alarms when the inert gas contains 5% or more oxygen by volume. ...

46 CFR 154.906 - Inert gas generators.

Code of Federal Regulations, 2011 CFR

2011-10-01

...: (a) Produce an inert gas containing less than 5% oxygen by volume; (b) Have a device to continuously sample the discharge of the generator for oxygen content; and (c) Have an audible and visual alarm in the cargo control station that alarms when the inert gas contains 5% or more oxygen by volume. ...

46 CFR 154.906 - Inert gas generators.

Code of Federal Regulations, 2010 CFR

2010-10-01

...: (a) Produce an inert gas containing less than 5% oxygen by volume; (b) Have a device to continuously sample the discharge of the generator for oxygen content; and (c) Have an audible and visual alarm in the cargo control station that alarms when the inert gas contains 5% or more oxygen by volume. ...

Multiple sclerosis lesions affect intrinsic functional connectivity of the spinal cord.

PubMed

Conrad, Benjamin N; Barry, Robert L; Rogers, Baxter P; Maki, Satoshi; Mishra, Arabinda; Thukral, Saakshi; Sriram, Subramaniam; Bhatia, Aashim; Pawate, Siddharama; Gore, John C; Smith, Seth A

2018-06-01

Patients with multiple sclerosis present with focal lesions throughout the spinal cord. There is a clinical need for non-invasive measurements of spinal cord activity and functional organization in multiple sclerosis, given the cord's critical role in the disease. Recent reports of spontaneous blood oxygenation level-dependent fluctuations in the spinal cord using functional MRI suggest that, like the brain, cord activity at rest is organized into distinct, synchronized functional networks among grey matter regions, likely related to motor and sensory systems. Previous studies looking at stimulus-evoked activity in the spinal cord of patients with multiple sclerosis have demonstrated increased levels of activation as well as a more bilateral distribution of activity compared to controls. Functional connectivity studies of brain networks in multiple sclerosis have revealed widespread alterations, which may take on a dynamic trajectory over the course of the disease, with compensatory increases in connectivity followed by decreases associated with structural damage. We build upon this literature by examining functional connectivity in the spinal cord of patients with multiple sclerosis. Using ultra-high field 7 T imaging along with processing strategies for robust spinal cord functional MRI and lesion identification, the present study assessed functional connectivity within cervical cord grey matter of patients with relapsing-remitting multiple sclerosis (n = 22) compared to a large sample of healthy controls (n = 56). Patient anatomical images were rated for lesions by three independent raters, with consensus ratings revealing 19 of 22 patients presented with lesions somewhere in the imaged volume. Linear mixed models were used to assess effects of lesion location on functional connectivity. Analysis in control subjects demonstrated a robust pattern of connectivity among ventral grey matter regions as well as a distinct network among dorsal regions. A gender effect was also observed in controls whereby females demonstrated higher ventral network connectivity. Wilcoxon rank-sum tests detected no differences in average connectivity or power of low frequency fluctuations in patients compared to controls. The presence of lesions was, however, associated with local alterations in connectivity with differential effects depending on columnar location. The patient results suggest that spinal cord functional networks are generally intact in relapsing-remitting multiple sclerosis but that lesions are associated with focal abnormalities in intrinsic connectivity. These findings are discussed in light of the current literature on spinal cord functional MRI and the potential neurological underpinnings.

Manganese-oxidizing photosynthesis before the rise of cyanobacteria.

PubMed

Johnson, Jena E; Webb, Samuel M; Thomas, Katherine; Ono, Shuhei; Kirschvink, Joseph L; Fischer, Woodward W

2013-07-09

The emergence of oxygen-producing (oxygenic) photosynthesis fundamentally transformed our planet; however, the processes that led to the evolution of biological water splitting have remained largely unknown. To illuminate this history, we examined the behavior of the ancient Mn cycle using newly obtained scientific drill cores through an early Paleoproterozoic succession (2.415 Ga) preserved in South Africa. These strata contain substantial Mn enrichments (up to ∼17 wt %) well before those associated with the rise of oxygen such as the ∼2.2 Ga Kalahari Mn deposit. Using microscale X-ray spectroscopic techniques coupled to optical and electron microscopy and carbon isotope ratios, we demonstrate that the Mn is hosted exclusively in carbonate mineral phases derived from reduction of Mn oxides during diagenesis of primary sediments. Additional observations of independent proxies for O2--multiple S isotopes (measured by isotope-ratio mass spectrometry and secondary ion mass spectrometry) and redox-sensitive detrital grains--reveal that the original Mn-oxide phases were not produced by reactions with O2, which points to a different high-potential oxidant. These results show that the oxidative branch of the Mn cycle predates the rise of oxygen, and provide strong support for the hypothesis that the water-oxidizing complex of photosystem II evolved from a former transitional photosystem capable of single-electron oxidation reactions of Mn.

Ethanol dehydration to ethylene in a stratified autothermal millisecond reactor.

PubMed

Skinner, Michael J; Michor, Edward L; Fan, Wei; Tsapatsis, Michael; Bhan, Aditya; Schmidt, Lanny D

2011-08-22

The concurrent decomposition and deoxygenation of ethanol was accomplished in a stratified reactor with 50-80 ms contact times. The stratified reactor comprised an upstream oxidation zone that contained Pt-coated Al(2)O(3) beads and a downstream dehydration zone consisting of H-ZSM-5 zeolite films deposited on Al(2)O(3) monoliths. Ethanol conversion, product selectivity, and reactor temperature profiles were measured for a range of fuel:oxygen ratios for two autothermal reactor configurations using two different sacrificial fuel mixtures: a parallel hydrogen-ethanol feed system and a series methane-ethanol feed system. Increasing the amount of oxygen relative to the fuel resulted in a monotonic increase in ethanol conversion in both reaction zones. The majority of the converted carbon was in the form of ethylene, where the ethanol carbon-carbon bonds stayed intact while the oxygen was removed. Over 90% yield of ethylene was achieved by using methane as a sacrificial fuel. These results demonstrate that noble metals can be successfully paired with zeolites to create a stratified autothermal reactor capable of removing oxygen from biomass model compounds in a compact, continuous flow system that can be configured to have multiple feed inputs, depending on process restrictions. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Atomic oxygen reactor having at least one sidearm conduit

NASA Technical Reports Server (NTRS)

Koontz, Steven L. (Inventor)

1994-01-01

An apparatus for treating a microporous structure with atomic oxygen is presented. The apparatus includes a main gas chamber for flowing gas in an axial direction and a source of gas, containing atomic oxygen, connected for introducing the gas into the main gas chamber. The apparatus employs at least one side arm extending from the main atomic oxygen-containing chamber. The side arm has characteristic relaxation times such that a uniform atomic oxygen dose rate is delivered to a specimen positioned transversely in the side arm spaced from the main gas chamber.

Atmospheric oxygen level and the evolution of insect body size.

PubMed

Harrison, Jon F; Kaiser, Alexander; VandenBrooks, John M

2010-07-07

Insects are small relative to vertebrates, possibly owing to limitations or costs associated with their blind-ended tracheal respiratory system. The giant insects of the late Palaeozoic occurred when atmospheric PO(2) (aPO(2)) was hyperoxic, supporting a role for oxygen in the evolution of insect body size. The paucity of the insect fossil record and the complex interactions between atmospheric oxygen level, organisms and their communities makes it impossible to definitively accept or reject the historical oxygen-size link, and multiple alternative hypotheses exist. However, a variety of recent empirical findings support a link between oxygen and insect size, including: (i) most insects develop smaller body sizes in hypoxia, and some develop and evolve larger sizes in hyperoxia; (ii) insects developmentally and evolutionarily reduce their proportional investment in the tracheal system when living in higher aPO(2), suggesting that there are significant costs associated with tracheal system structure and function; and (iii) larger insects invest more of their body in the tracheal system, potentially leading to greater effects of aPO(2) on larger insects. Together, these provide a wealth of plausible mechanisms by which tracheal oxygen delivery may be centrally involved in setting the relatively small size of insects and for hyperoxia-enabled Palaeozoic gigantism.

Extracorporeal membrane oxygenation and cytokine adsorption

PubMed Central

Träger, Karl

2018-01-01

Extracorporeal membrane oxygenation (ECMO) is an increasingly used technology for mechanical support of respiratory and cardio-circulatory failure. Excessive systemic inflammatory response is observed during sepsis and after cardiopulmonary bypass (CPB) with similar clinical features. The overwhelming inflammatory response is characterized by highly elevated pro- and anti-inflammatory cytokine levels. The excessive cytokine release during the overwhelming inflammatory response may result in multiple organ damage and failure. During ECMO therapy activation of complement and contact systems occur which may be followed by cytokine release. Controlling excessively increased cytokines may be considered as a valuable treatment option. Hemoadsorption therapy may be used to decrease cytokine levels in case of excessive inflammatory response and due to its unspecific adsorptive characteristics also substances like myoglobin, free hemoglobin or bilirubin. Controlling pro-inflammatory response with hemoadsorption may have positive impact on the endothelial glycocalix and also may be advantageous for maintenance of the vascular barrier function which plays a pivotal role in the development of tissue edema and oxygen mismatch. Hemoadsorption therapy seems to offer a promising new option for the treatment of patients with overwhelming inflammatory response leading to faster hemodynamic and metabolic stabilization finally resulting in preserved organ functions. PMID:29732183

Extracorporeal membrane oxygenation and cytokine adsorption.

PubMed

Datzmann, Thomas; Träger, Karl

2018-03-01

Extracorporeal membrane oxygenation (ECMO) is an increasingly used technology for mechanical support of respiratory and cardio-circulatory failure. Excessive systemic inflammatory response is observed during sepsis and after cardiopulmonary bypass (CPB) with similar clinical features. The overwhelming inflammatory response is characterized by highly elevated pro- and anti-inflammatory cytokine levels. The excessive cytokine release during the overwhelming inflammatory response may result in multiple organ damage and failure. During ECMO therapy activation of complement and contact systems occur which may be followed by cytokine release. Controlling excessively increased cytokines may be considered as a valuable treatment option. Hemoadsorption therapy may be used to decrease cytokine levels in case of excessive inflammatory response and due to its unspecific adsorptive characteristics also substances like myoglobin, free hemoglobin or bilirubin. Controlling pro-inflammatory response with hemoadsorption may have positive impact on the endothelial glycocalix and also may be advantageous for maintenance of the vascular barrier function which plays a pivotal role in the development of tissue edema and oxygen mismatch. Hemoadsorption therapy seems to offer a promising new option for the treatment of patients with overwhelming inflammatory response leading to faster hemodynamic and metabolic stabilization finally resulting in preserved organ functions.

Interfacial Strength and Physical Properties of Functionalized Graphene - Epoxy Nanocomposites

NASA Technical Reports Server (NTRS)

Miller, Sandi G.; Heimann, Paula; Scheiman, Daniel; Adamson, Douglas H.; Aksay, Iihan A.; Prud'homme, Robert K.

2006-01-01

The toughness and coefficient of thermal expansion of a series of functionalized graphene sheet - epoxy nanocomposites are investigated. Functionalized graphene sheets are produced by splitting graphite oxide into single graphene sheets through a rapid thermal expansion process. These graphene sheets contain approx. 10% oxygen due to the presence of hydroxide, epoxide, and carboxyl functional groups which assist in chemical bond formation with the epoxy matrix. Intrinsic surface functionality is used to graft alkyl amine chains on the graphene sheets, and the addition of excess hardener insures covalent bonding between the epoxide matrix and graphene sheets. Considerable improvement in the epoxy dimensional stability is obtained. An increase in nanocomposite toughness is observed in some cases.

Comparison on graphite, graphene oxide and reduced graphene oxide: Synthesis and characterization

NASA Astrophysics Data System (ADS)

Hidayah, N. M. S.; Liu, Wei-Wen; Lai, Chin-Wei; Noriman, N. Z.; Khe, Cheng-Seong; Hashim, U.; Lee, H. Cheun

2017-10-01

Graphene oxide (GO) and reduced graphene oxide (RGO) are known to have superior properties for various applications. This work compares the properties of GO and RGO with graphite. GO was prepared by using Improved Hummer's method whereas the produced GO was subjected to chemical reduction with the use of hydrazine hydrate. Graphite, GO and RGO had different morphologies, quality, functionalized groups, UV-Vis absorption peaks and crystallinity. With the removal of oxygen-containing functional group during reduction for RGO, the quality of samples was decreased due to higher intensity of D band than G band was seen in Raman results. In addition, platelet-like surface can be observed on the surface of graphite as compared to GO and RGO where wrinkled and layered flakes, and crumpled thin sheets were observed on GO and RGO surface respectively. Fourier Transform Infra-Red (FTIR) analysis showed the presence of abundant oxygen-containing functional groups in GO as compared to RGO and graphite. The characteristic peaks at 26.62°, 9.03° and 24.10° for graphite, GO and RGO, respectively, can be detected from X-Ray diffraction (XRD). Furthermore, the reduction also caused red shift at 279nm from 238nm, as obtained from ultraviolet visible (UV-Vis) analysis. The results proved that GO was successfully oxidized from graphite whereas RGO was effectively reduced from GO.

Near infrared radiation rescues mitochondrial dysfunction in cortical neurons after oxygen-glucose deprivation.

PubMed

Yu, Zhanyang; Liu, Ning; Zhao, Jianhua; Li, Yadan; McCarthy, Thomas J; Tedford, Clark E; Lo, Eng H; Wang, Xiaoying

2015-04-01

Near infrared radiation (NIR) is known to penetrate and affect biological systems in multiple ways. Recently, a series of experimental studies suggested that low intensity NIR may protect neuronal cells against a wide range of insults that mimic diseases such as stroke, brain trauma and neurodegeneration. However, the potential molecular mechanisms of neuroprotection with NIR remain poorly defined. In this study, we tested the hypothesis that low intensity NIR may attenuate hypoxia/ischemia-induced mitochondrial dysfunction in neurons. Primary cortical mouse neuronal cultures were subjected to 4 h oxygen-glucose deprivation followed by reoxygenation for 2 h, neurons were then treated with a 2 min exposure to 810-nm NIR. Mitochondrial function markers including MTT reduction and mitochondria membrane potential were measured at 2 h after treatment. Neurotoxicity was quantified 20 h later. Our results showed that 4 h oxygen-glucose deprivation plus 20 h reoxygenation caused 33.8 ± 3.4 % of neuron death, while NIR exposure significantly reduced neuronal death to 23.6 ± 2.9 %. MTT reduction rate was reduced to 75.9 ± 2.7 % by oxygen-glucose deprivation compared to normoxic controls, but NIR exposure significantly rescued MTT reduction to 87.6 ± 4.5 %. Furthermore, after oxygen-glucose deprivation, mitochondria membrane potential was reduced to 48.9 ± 4.39 % of normoxic control, while NIR exposure significantly ameliorated this reduction to 89.6 ± 13.9 % of normoxic control. Finally, NIR significantly rescued OGD-induced ATP production decline at 20 min after NIR. These findings suggest that low intensity NIR can protect neurons against oxygen-glucose deprivation by rescuing mitochondrial function and restoring neuronal energetics.

Near infrared radiation rescues mitochondrial dysfunction in cortical neurons after oxygen-glucose deprivation

PubMed Central

Yu, Zhanyang; Liu, Ning; Zhao, Jianhua; Li, Yadan; McCarthy, Thomas J.; Tedford, Clark E.; Lo, Eng H.; Wang, Xiaoying

2014-01-01

Near infrared radiation (NIR) is known to penetrate and affect biological systems in multiple ways. Recently, a series of experimental studies suggested that low intensity NIR may protect neuronal cells against a wide range of insults that mimic diseases such as stroke, brain trauma and neuro-degeneration. However, the potential molecular mechanisms of neuroprotection with NIR remain poorly defined. In this study, we tested the hypothesis that low intensity NIR may attenuate hypoxia/ischemia-induced mitochondrial dysfunction in neurons. Primary cortical mouse neuronal cultures were subjected to 4 h oxygen-glucose deprivation followed by reoxygenation for 2 h, neurons were then treated with a 2 min exposure to 810-nm NIR. Mitochondrial function markers including MTT reduction and mitochondria membrane potential were measured at 2 h after treatment. Neurotoxicity was quantified 20 h later. Our results showed that 4 h oxygen-glucose deprivation plus 20 h reoxygenation caused 33.8±3.4 % of neuron death, while NIR exposure significantly reduced neuronal death to 23.6±2.9 %. MTT reduction rate was reduced to 75.9±2.7 % by oxygen-glucose deprivation compared to normoxic controls, but NIR exposure significantly rescued MTT reduction to 87.6±4.5 %. Furthermore, after oxygen-glucose deprivation, mitochondria membrane potential was reduced to 48.9±4.39 % of normoxic control, while NIR exposure significantly ameliorated this reduction to 89.6±13.9 % of normoxic control. Finally, NIR significantly rescued OGD-induced ATP production decline at 20 min after NIR. These findings suggest that low intensity NIR can protect neurons against oxygen-glucose deprivation by rescuing mitochondrial function and restoring neuronal energetics. PMID:24599760

Signal transduction and phosphoryl transfer by a FixL hybrid kinase with low oxygen affinity: importance of the vicinal PAS domain and receiver aspartate.

PubMed

Sousa, Eduardo H S; Tuckerman, Jason R; Gondim, Ana C S; Gonzalez, Gonzalo; Gilles-Gonzalez, Marie-Alda

2013-01-22

FixL is a prototype for heme-based sensors, multidomain proteins that typically couple a histidine protein kinase activity to a heme-binding domain for sensing of diatomic gases such as oxygen, carbon monoxide, and nitric oxide. Despite the relatively well-developed understanding of FixL, the importance of some of its domains has been unclear. To explore the impact of domain-domain interactions on oxygen sensing and signal transduction, we characterized and investigated Rhizobium etli hybrid sensor ReFixL. In ReFixL, the core heme-containing PAS domain and kinase region is preceded by an N-terminal PAS domain of unknown function and followed by a C-terminal receiver domain. The latter resembles a target substrate domain that usually occurs independently of the kinase and contains a phosphorylatable aspartate residue. We isolated the full-length ReFixL as a soluble holoprotein with a single heme b cofactor. Despite a low affinity for oxygen (K(d) for O₂ of 738 μM), the kinase activity was completely switched off by O₂ at concentrations well below the K(d). A deletion of the first PAS domain strongly increased the oxygen affinity but essentially prohibited autophosphorylation, although the truncated protein was competent to accept phosphoryl groups in trans. These studies provide new insights into histidyl-aspartyl phosphoryl transfers in two-component systems and suggest that the control of ligand affinity and signal transduction by PAS domains can be direct or indirect.

Disorder and function: a review of the dehydrin protein family

PubMed Central

Graether, Steffen P.; Boddington, Kelly F.

2014-01-01

Dehydration proteins (dehydrins) are group 2 members of the late embryogenesis abundant (LEA) protein family. The protein architecture of dehydrins can be described by the presence of three types of conserved sequence motifs that have been named the K-, Y-, and S-segments. By definition, a dehydrin must contain at least one copy of the lysine-rich K-segment. Abiotic stresses such as drought, cold, and salinity cause the upregulation of dehydrin mRNA and protein levels. Despite the large body of genetic and protein evidence of the importance of these proteins in stress response, the in vivo protective mechanism is not fully known. In vitro experimental evidence from biochemical assays and localization experiments suggests multiple roles for dehydrins, including membrane protection, cryoprotection of enzymes, and protection from reactive oxygen species. Membrane binding by dehydrins is likely to be as a peripheral membrane protein, since the protein sequences are highly hydrophilic and contain many charged amino acids. Because of this, dehydrins in solution are intrinsically disordered proteins, that is, they have no well-defined secondary or tertiary structure. Despite their disorder, dehydrins have been shown to gain structure when bound to ligands such as membranes, and to possibly change their oligomeric state when bound to ions. We review what is currently known about dehydrin sequences and their structures, and examine the various ligands that have been shown to bind to this family of proteins. PMID:25400646

Crosslinked Polyamide

DOEpatents

Huang, Zhi H.; McDonald, William F.; Wright, Stacy C.; Taylor, Andrew C.

2002-06-04

A crosslinked polyamide material and a process for preparing the crosslinked polyamide material are disclosed. The crosslinked polyamide material comprises a crosslinked chemical combination of (1) a polyamide of the formula: ##STR1## wherein n is between about 50 and 10,000, wherein each R is between 1 and 50 carbon atoms alone and is optionally substituted with heteroatoms, oxygen, nitrogen, sulfur, or phosphorus and combinations thereof, wherein multiple of the R are in vertically aligned spaced relationship along a backbone forming the polyamide, and wherein two or more of the R contain an amino group; and (2) a crosslinking agent containing at least two functional groups capable of reacting with the amino groups of the polyamide. In one embodiment of the invention, the crosslinking agent is an aliphatic or aromatic isocyanate compound having 2 or more --N.dbd.C.dbd.O groups. In another embodiment of the invention, the crosslinking agent is an aliphatic aldehyde or aromatic aldehyde compound having 2 or more --CHO groups. In still another embodiment of the invention, the crosslinking agent is selected from a phosphine having the general formula (A).sub.2 P(B) and mixtures thereof, wherein A is hydroxyalkyl, and B is hydroxyalkyl, alkyl, or aryl. In yet another embodiment of the invention, the crosslinking agent is selected from the group consisting of epoxy resins having more than one epoxide group per molecule.

RegA Plays a Key Role in Oxygen-Dependent Establishment of Persistence and in Isocitrate Lyase Activity, a Critical Determinant of In vivo Brucella suis Pathogenicity

PubMed Central

Abdou, Elias; Jiménez de Bagüés, María P.; Martínez-Abadía, Ignacio; Ouahrani-Bettache, Safia; Pantesco, Véronique; Occhialini, Alessandra; Al Dahouk, Sascha; Köhler, Stephan; Jubier-Maurin, Véronique

2017-01-01

For aerobic human pathogens, adaptation to hypoxia is a critical factor for the establishment of persistent infections, as oxygen availability is low inside the host. The two-component system RegB/A of Brucella suis plays a central role in the control of respiratory systems adapted to oxygen deficiency, and in persistence in vivo. Using an original “in vitro model of persistence” consisting in gradual oxygen depletion, we compared transcriptomes and proteomes of wild-type and ΔregA strains to identify the RegA-regulon potentially involved in the set-up of persistence. Consecutive to oxygen consumption resulting in growth arrest, 12% of the genes in B. suis were potentially controlled directly or indirectly by RegA, among which numerous transcriptional regulators were up-regulated. In contrast, genes or proteins involved in envelope biogenesis and in cellular division were repressed, suggesting a possible role for RegA in the set-up of a non-proliferative persistence state. Importantly, the greatest number of the RegA-repressed genes and proteins, including aceA encoding the functional IsoCitrate Lyase (ICL), were involved in energy production. A potential consequence of this RegA impact may be the slowing-down of the central metabolism as B. suis progressively enters into persistence. Moreover, ICL is an essential determinant of pathogenesis and long-term interactions with the host, as demonstrated by the strict dependence of B. suis on ICL activity for multiplication and persistence during in vivo infection. RegA regulates gene or protein expression of all functional groups, which is why RegA is a key regulator of B. suis in adaptation to oxygen depletion. This function may contribute to the constraint of bacterial growth, typical of chronic infection. Oxygen-dependent activation of two-component systems that control persistence regulons, shared by several aerobic human pathogens, has not been studied in Brucella sp. before. This work therefore contributes significantly to the unraveling of persistence mechanisms in this important zoonotic pathogen. PMID:28573107

The Effects of Direct Oxygen Supply During Static Cold Preservation of Rat Livers: An Experimental Study.

PubMed

Zumrutdal, Emin; Karateke, Faruk; Eser, Pınar Eylem; Turan, Umit; Ozyazici, Sefa; Sozutek, Alper; Gulkaya, Mustafa; Kunt, Mevlut

2016-12-01

We aimed to determine the biochemical and histopathologic effects of direct oxygen supply to the preservation fluid of static cold storage system with a simple method on rat livers. Sixteen rats were randomly divided into 2 groups: the control group, which contained Ringer's lactate as preservation fluid; and the oxygen group, which contained oxygen and Ringer's lactate for preservation. Each liver was placed in a bag containing 50 mL Ringer's lactate and placed in ice-filled storage containers. One hundred percent oxygen supplies were given via a simple, inexpensive system created in our laboratory, to the livers in oxygen group. We obtained samples for histopathologic evaluation in the 12th hour. In addition, 3 mL of preservation fluid was subjected to biochemical analysis at 0, sixth, and twelfth hours. Aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and pH levels were measured from the preservation fluid. In oxygen-supplemented group, the acceleration speed of increase in alanine aminotransferase and lactate dehydrogenase levels at sixth hour and lactate dehydrogenase, alanine aminotransferase, and lactate dehydrogenase levels at 12th hour were statistically significantly reduced. In histopathologic examination, all parameters except ballooning were statistically significantly better in the oxygen-supplemented group. This simple system for oxygenation of liver tissues during static cold storage was shown to be effective with good results in biochemical and histopathologic assessments. Because this is a simple, inexpensive, and easily available method, larger studies are warranted to evaluate its effects (especially in humans).

High cell density media for Escherichia coli are generally designed for aerobic cultivations – consequences for large-scale bioprocesses and shake flask cultures

PubMed Central

Soini, Jaakko; Ukkonen, Kaisa; Neubauer, Peter

2008-01-01

Background For the cultivation of Escherichia coli in bioreactors trace element solutions are generally designed for optimal growth under aerobic conditions. They do normally not contain selenium and nickel. Molybdenum is only contained in few of them. These elements are part of the formate hydrogen lyase (FHL) complex which is induced under anaerobic conditions. As it is generally known that oxygen limitation appears in shake flask cultures and locally in large-scale bioreactors, function of the FHL complex may influence the process behaviour. Formate has been described to accumulate in large-scale cultures and may have toxic effects on E. coli. Although the anaerobic metabolism of E. coli is well studied, reference data which estimate the impact of the FHL complex on bioprocesses of E. coli with oxygen limitation have so far not been published, but are important for a better process understanding. Results Two sets of fed-batch cultures with conditions triggering oxygen limitation and formate accumulation were performed. Permanent oxygen limitation which is typical for shake flask cultures was caused in a bioreactor by reduction of the agitation rate. Transient oxygen limitation, which has been described to eventually occur in the feed-zone of large-scale bioreactors, was mimicked in a two-compartment scale-down bioreactor consisting of a stirred tank reactor and a plug flow reactor (PFR) with continuous glucose feeding into the PFR. In both models formate accumulated up to about 20 mM in the culture medium without addition of selenium, molybdenum and nickel. By addition of these trace elements the formate accumulation decreased below the level observed in well-mixed laboratory-scale cultures. Interestingly, addition of the extra trace elements caused accumulation of large amounts of lactate and reduced biomass yield in the simulator with permanent oxygen limitation, but not in the scale-down two-compartment bioreactor. Conclusion The accumulation of formate in oxygen limited cultivations of E. coli can be fully prevented by addition of the trace elements selenium, nickel and molybdenum, necessary for the function of FHL complex. For large-scale cultivations, if glucose gradients are likely, the results from the two-compartment scale-down bioreactor indicate that the addition of the extra trace elements is beneficial. No negative effects on the biomass yield or on any other bioprocess parameters could be observed in cultures with the extra trace elements if the cells were repeatedly exposed to transient oxygen limitation. PMID:18687130

Emission FTIR analyses of thin microscopic patches of jet fuel residue deposited on heated metal surface

NASA Technical Reports Server (NTRS)

Lauer, J. L.; Vogel, P.

1984-01-01

Deposits laid down in patches on metal strips in a high pressure/high temperature fuel system simulator operated with aerated fuel at varying flow rates were analyzed by emission FTIR in terms of functional groups. Significant differences were found in the spectra and amounts of deposits derived from fuels to which small concentrations of oxygen-, nitrogen-, or sulfur-containing heterocyclics or metal naphthenates were added. The spectra of deposits generated on strips by heating fuels and air in a closed container were very different from those of the flowing fluid deposits. One such closed-container dodecane deposit on silver gave a strong surface-enhanced Raman spectrum.

CHARACTERIZATION OF EMISSIONS FROM MALFUNCTIONING VEHICLES FUELED WITH OXYGENATED GASOLINE-ETHANOL (E-10) FUEL-PART II

EPA Science Inventory

A 1993 Ford Taurus and a 1995 Chevrolet Achieva were tested using three different fuels: (1) a winter grade (E-10) fuel containing 10% (vol.) 200 proof ethanol, (2) a winter grade (WG) fuel without any oxygen containing compounds, and (3) a summer grade (SG) fuel without oxygen...

Functional High-Intensity Circuit Training Improves Body Composition, Peak Oxygen Uptake, Strength, and Alters Certain Dimensions of Quality of Life in Overweight Women.

PubMed

Sperlich, Billy; Wallmann-Sperlich, Birgit; Zinner, Christoph; Von Stauffenberg, Valerie; Losert, Helena; Holmberg, Hans-Christer

2017-01-01

The effects of circuit-like functional high-intensity training (Circuit HIIT ) alone or in combination with high-volume low-intensity exercise (Circuit combined ) on selected cardio-respiratory and metabolic parameters, body composition, functional strength and the quality of life of overweight women were compared. In this single-center, two-armed randomized, controlled study, overweight women performed 9-weeks (3 sessions·wk -1 ) of either Circuit HIIT ( n = 11), or Circuit combined ( n = 8). Peak oxygen uptake and perception of physical pain were increased to a greater extent ( p < 0.05) by Circuit HIIT , whereas Circuit combined improved perception of general health more ( p < 0.05). Both interventions lowered body mass, body-mass-index, waist-to-hip ratio, fat mass, and enhanced fat-free mass; decreased ratings of perceived exertion during submaximal treadmill running; improved the numbers of push-ups, burpees, one-legged squats, and 30-s skipping performed, as well as the height of counter-movement jumps; and improved physical and social functioning, role of physical limitations, vitality, role of emotional limitations, and mental health to a similar extent (all p < 0.05). Either forms of these multi-stimulating, circuit-like, multiple-joint training can be employed to improve body composition, selected variables of functional strength, and certain dimensions of quality of life in overweight women. However, Circuit HIIT improves peak oxygen uptake to a greater extent, but with more perception of pain, whereas Circuit combined results in better perception of general health.

Functional High-Intensity Circuit Training Improves Body Composition, Peak Oxygen Uptake, Strength, and Alters Certain Dimensions of Quality of Life in Overweight Women

PubMed Central

Sperlich, Billy; Wallmann-Sperlich, Birgit; Zinner, Christoph; Von Stauffenberg, Valerie; Losert, Helena; Holmberg, Hans-Christer

2017-01-01

The effects of circuit-like functional high-intensity training (CircuitHIIT) alone or in combination with high-volume low-intensity exercise (Circuitcombined) on selected cardio-respiratory and metabolic parameters, body composition, functional strength and the quality of life of overweight women were compared. In this single-center, two-armed randomized, controlled study, overweight women performed 9-weeks (3 sessions·wk−1) of either CircuitHIIT (n = 11), or Circuitcombined (n = 8). Peak oxygen uptake and perception of physical pain were increased to a greater extent (p < 0.05) by CircuitHIIT, whereas Circuitcombined improved perception of general health more (p < 0.05). Both interventions lowered body mass, body-mass-index, waist-to-hip ratio, fat mass, and enhanced fat-free mass; decreased ratings of perceived exertion during submaximal treadmill running; improved the numbers of push-ups, burpees, one-legged squats, and 30-s skipping performed, as well as the height of counter-movement jumps; and improved physical and social functioning, role of physical limitations, vitality, role of emotional limitations, and mental health to a similar extent (all p < 0.05). Either forms of these multi-stimulating, circuit-like, multiple-joint training can be employed to improve body composition, selected variables of functional strength, and certain dimensions of quality of life in overweight women. However, CircuitHIIT improves peak oxygen uptake to a greater extent, but with more perception of pain, whereas Circuitcombined results in better perception of general health. PMID:28420999

Element- and charge-state-resolved ion energies in the cathodic arc plasma from composite AlCr cathodes in argon, nitrogen and oxygen atmospheres

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

Franz, Robert; Polcik, Peter; Anders, André

The energy distribution functions of ions in the cathodic arc plasma using composite AlCr cathodes were measured as a function of the background gas pressure in the range 0.5 to 3.5 Pa for different cathode compositions and gas atmospheres. The most abundant aluminium ions were Al+ regardless of the background gas species, whereas Cr 2+ ions were dominating in Ar and N 2 and Cr + in O 2 atmospheres. The energy distributions of the aluminium and chromium ions typically consisted of a high-energy fraction due to acceleration in the expanding plasma plume from the cathode spot and thermalised ionsmore » that were subjected to collisions in the plasma cloud. The fraction of the latter increased with increasing background gas pressure. Atomic nitrogen and oxygen ions showed similar energy distributions as the aluminium and chromium ions, whereas the argon and molecular nitrogen and oxygen ions were formed at greater distance from the cathode spot and thus less subject to accelerating gradients. In addition to the positively charged metal and gas ions, negatively charged oxygen and oxygen-containing ions were observed in O 2 atmosphere. The obtained results are intended to provide a comprehensive overview of the ion energies and charge states in the arc plasma of AlCr composite cathodes in different gas atmospheres as such plasmas are frequently used to deposit thin films and coatings.« less

Element- and charge-state-resolved ion energies in the cathodic arc plasma from composite AlCr cathodes in argon, nitrogen and oxygen atmospheres

DOE PAGES

Franz, Robert; Polcik, Peter; Anders, André

2015-06-01

The energy distribution functions of ions in the cathodic arc plasma using composite AlCr cathodes were measured as a function of the background gas pressure in the range 0.5 to 3.5 Pa for different cathode compositions and gas atmospheres. The most abundant aluminium ions were Al+ regardless of the background gas species, whereas Cr 2+ ions were dominating in Ar and N 2 and Cr + in O 2 atmospheres. The energy distributions of the aluminium and chromium ions typically consisted of a high-energy fraction due to acceleration in the expanding plasma plume from the cathode spot and thermalised ionsmore » that were subjected to collisions in the plasma cloud. The fraction of the latter increased with increasing background gas pressure. Atomic nitrogen and oxygen ions showed similar energy distributions as the aluminium and chromium ions, whereas the argon and molecular nitrogen and oxygen ions were formed at greater distance from the cathode spot and thus less subject to accelerating gradients. In addition to the positively charged metal and gas ions, negatively charged oxygen and oxygen-containing ions were observed in O 2 atmosphere. The obtained results are intended to provide a comprehensive overview of the ion energies and charge states in the arc plasma of AlCr composite cathodes in different gas atmospheres as such plasmas are frequently used to deposit thin films and coatings.« less

In vivo determination of multiple indices of periodontal inflammation by optical spectroscopy

PubMed Central

Liu, KZ; Xiang, XM; Man, A; Sowa, MG; Cholakis, N; Ghiabi, E; Singer, DL; Scott, DA

2008-01-01

Background and Objective Visible – near infrared (optical) spectroscopy can be used to measure regional tissue hemodynamics and edema and, therefore, may represent an ideal tool with which to non-invasively study periodontal inflammation. The study objective was to evaluate the ability of optical spectroscopy to simultaneously determine multiple inflammatory indices (tissue oxygenation, total tissue hemoglobin, deoxyhemoglobin, oxygenated hemoglobin, and tissue edema) in periodontal tissues in vivo. Material and Methods Spectra were obtained, processed, and evaluated from healthy, gingivitis, and periodontitis sites (n = 133) using a portable optical – near infrared spectrometer. A modified Beer-Lambert unmixing model that incorporates a nonparametric scattering loss function was used to determine the relative contribution of each inflammatory component to the overall spectrum. Results Optical spectroscopy was harnessed to successfully generate complex inflammatory profiles in periodontal tissues. Tissue oxygenation at periodontitis sites was significantly decreased (p<0.05) compared to gingivitis and healthy controls. This is largely due to an increase in deoxyhemoglobin in the periodontitis sites compared to healthy (p<0.01) and gingivitis (p=0.05) sites. Tissue water content per se showed no significant difference between the sites but a water index associated with tissue electrolyte levels and temperature differed was significantly between periodontitis sites when compared to both healthy and gingivitis sites (p<0.03). Conclusion This study establishes that optical spectroscopy can simultaneously determine multiple inflammatory indices directly in the periodontal tissues in vivo. Visible - near infrared spectroscopy has the potential to be developed into a simple, reagent-free, user friendly, chair-side, site-specific, diagnostic and prognostic test for periodontitis. PMID:18973538

Investigation of Dynamic Oxygen Adsorption in Molten Solder Jetting Technology

NASA Technical Reports Server (NTRS)

Megaridis, Constantine M.; Bellizia, Giulio; McNallan, Michael; Wallace, David B.

2003-01-01

Surface tension forces play a critical role in fluid dynamic phenomena that are important in materials processing. The surface tension of liquid metals has been shown to be very susceptible to small amounts of adsorbed oxygen. Consequently, the kinetics of oxygen adsorption can influence the capillary breakup of liquid-metal jets targeted for use in electronics assembly applications, where low-melting-point metals (such as tin-containing solders) are utilized as an attachment material for mounting of electronic components to substrates. By interpreting values of surface tension measured at various surface ages, adsorption and diffusion rates of oxygen on the surface of the melt can be estimated. This research program investigates the adsorption kinetics of oxygen on the surface of an atomizing molten-metal jet. A novel oscillating capillary jet method has been developed for the measurement of dynamic surface tension of liquids, and in particular, metal melts which are susceptible to rapid surface degradation caused by oxygen adsorption. The experimental technique captures the evolution of jet swells and necks continuously along the jet propagation axis and is used in conjunction with an existing linear, axisymmetric, constant-property model to determine the variation of the instability growth rate, and, in turn, surface tension of the liquid as a function of surface age measured from the exit orifice. The conditions investigated so far focus on a time window of 2-4ms from the jet orifice. The surface properties of the eutectic 63%Sn-37%Pb solder alloy have been investigated in terms of their variation due to O2 adsorption from a N2 atmosphere containing controlled amounts of oxygen (from 8 ppm to 1000 ppm). The method performed well for situations where the oxygen adsorption was low in that time window. The value of surface tension for the 63Sn-37Pb solder in pure nitrogen was found to be 0.49 N/m, in good agreement with previously published work. A characteristic time of O(1ms) or less was determined for the molten-metal surface to be saturated by oxygen at 1000 ppm concentration in N2.

Blood-Feeding Induces Reversible Functional Changes in Flight Muscle Mitochondria of Aedes aegypti Mosquito

PubMed Central

Gonçalves, Renata L. S.; Machado, Ana Carolina L.; Paiva-Silva, Gabriela O.; Sorgine, Marcos H. F.; Momoli, Marisa M.; Oliveira, Jose Henrique M.; Vannier-Santos, Marcos A.; Galina, Antonio; Oliveira, Pedro L.; Oliveira, Marcus F.

2009-01-01

Background Hematophagy poses a challenge to blood-feeding organisms since products of blood digestion can exert cellular deleterious effects. Mitochondria perform multiple roles in cell biology acting as the site of aerobic energy-transducing pathways, and also an important source of reactive oxygen species (ROS), modulating redox metabolism. Therefore, regulation of mitochondrial function should be relevant for hematophagous arthropods. Here, we investigated the effects of blood-feeding on flight muscle (FM) mitochondria from the mosquito Aedes aegypti, a vector of dengue and yellow fever. Methodology/Principal Findings Blood-feeding caused a reversible reduction in mitochondrial oxygen consumption, an event that was parallel to blood digestion. These changes were most intense at 24 h after blood meal (ABM), the peak of blood digestion, when oxygen consumption was inhibited by 68%. Cytochromes c and a+a 3 levels and cytochrome c oxidase activity of the electron transport chain were all reduced at 24 h ABM. Ultrastructural and molecular analyses of FM revealed that mitochondria fuse upon blood meal, a condition related to reduced ROS generation. Consistently, BF induced a reversible decrease in mitochondrial H2O2 formation during blood digestion, reaching their lowest values at 24 h ABM where a reduction of 51% was observed. Conclusion Blood-feeding triggers functional and structural changes in hematophagous insect mitochondria, which may represent an important adaptation to blood feeding. PMID:19924237

Antioxidant Activities of Functional Beverage Concentrates Containing Herbal Medicine Extracts.

PubMed

Park, Seon-Joo; Kim, Mi-Ok; Kim, Jung Hoan; Jeong, Sehyun; Kim, Min Hee; Yang, Su-Jin; Lee, Jongsung; Lee, Hae-Jeung

2017-03-01

This study investigated the antioxidant activity of functional beverage concentrates containing herbal medicine extracts (FBCH) using various antioxidant assays, such as 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging activity, and reducing power assay. The total polyphenolic content of FBCH (81.45 mg/100 g) was higher than Ssanghwa tea (SHT, 37.56 mg/100 g). The antioxidant activities of FBCH showed 52.92% DPPH and 55.18% ABTS radical scavenging activities at 100 mg/mL, respectively. FBCH showed significantly higher antioxidant activities compared to the SHT (DPPH, 23.43%; ABTS, 22.21%; reducing power optical density; 0.23, P <0.05). In addition, intracellular reactive oxygen species generation significantly decreased in a concentration-dependent manner following FBCH treatment. These results suggest that the addition of herbal medicine extract contributes to the improved functionality of beverage concentrates.

Thorium–phosphorus triamidoamine complexes containing Th–P single- and multiple-bond interactions

PubMed Central

Wildman, Elizabeth P.; Balázs, Gábor; Wooles, Ashley J.; Scheer, Manfred; Liddle, Stephen T.

2016-01-01

Despite the burgeoning field of uranium-ligand multiple bonds, analogous complexes involving other actinides remain scarce. For thorium, under ambient conditions only a few multiple bonds to carbon, nitrogen, oxygen, sulfur, selenium and tellurium are reported, and no multiple bonds to phosphorus are known, reflecting a general paucity of synthetic methodologies and also problems associated with stabilising these linkages at the large thorium ion. Here we report structurally authenticated examples of a parent thorium(IV)–phosphanide (Th–PH2), a terminal thorium(IV)–phosphinidene (Th=PH), a parent dithorium(IV)–phosphinidiide (Th–P(H)-Th) and a discrete actinide–phosphido complex under ambient conditions (Th=P=Th). Although thorium is traditionally considered to have dominant 6d-orbital contributions to its bonding, contrasting to majority 5f-orbital character for uranium, computational analyses suggests that the bonding of thorium can be more nuanced, in terms of 5f- versus 6d-orbital composition and also significant involvement of the 7s-orbital and how this affects the balance of 5f- versus 6d-orbital bonding character. PMID:27682617

Thorium-phosphorus triamidoamine complexes containing Th-P single- and multiple-bond interactions.

PubMed

Wildman, Elizabeth P; Balázs, Gábor; Wooles, Ashley J; Scheer, Manfred; Liddle, Stephen T

2016-09-29

Despite the burgeoning field of uranium-ligand multiple bonds, analogous complexes involving other actinides remain scarce. For thorium, under ambient conditions only a few multiple bonds to carbon, nitrogen, oxygen, sulfur, selenium and tellurium are reported, and no multiple bonds to phosphorus are known, reflecting a general paucity of synthetic methodologies and also problems associated with stabilising these linkages at the large thorium ion. Here we report structurally authenticated examples of a parent thorium(IV)-phosphanide (Th-PH 2 ), a terminal thorium(IV)-phosphinidene (Th=PH), a parent dithorium(IV)-phosphinidiide (Th-P(H)-Th) and a discrete actinide-phosphido complex under ambient conditions (Th=P=Th). Although thorium is traditionally considered to have dominant 6d-orbital contributions to its bonding, contrasting to majority 5f-orbital character for uranium, computational analyses suggests that the bonding of thorium can be more nuanced, in terms of 5f- versus 6d-orbital composition and also significant involvement of the 7s-orbital and how this affects the balance of 5f- versus 6d-orbital bonding character.

Investigation of Molecular Structure and Thermal Properties of Thermo-Oxidative Aged SBS in Blends and Their Relations

PubMed Central

Xu, Xiong; Yu, Jianying; Xue, Lihui; Zhang, Canlin; Zha, Yagang; Gu, Yi

2017-01-01

Tri-block copolymer styrene–butadiene (SBS) is extensively applied in bituminous highway construction due to its high elasticity and excellent weather resistance. With the extension of time, tri-block structural SBS automatically degrades into bi-block structural SB- with some terminal oxygen-containing groups under the comprehensive effects of light, heat, oxygen, etc. In this paper, the effects of aging temperature, aging time and oxygen concentration on the molecular structure of thermo-oxidative aged SBS were mainly investigated using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), and the correlation between oxygen-containing groups and thermal properties (TG–DTG) was further discussed. The FTIR and XPS results show that rapid decomposition of SBS will occur with increments of aging temperature, aging time and oxygen concentration, and a large number of oxygen-containing groups such as –OH, C=O, –COOH, etc. will be formed during thermo-oxidative aging. In short-term aging, changes in aging temperature and oxygen concentration have a significant impact on the structural damage of SBS. However, in long-term aging, it has no further effect on the molecular structure of SBS or on increasing oxygen concentration. The TG and DTG results indicate that the concentration of substances with low molecular weight gradually increases with the improvement of the degree of aging of the SBS, while the initial decomposition rate increases at the beginning of thermal weightlessness and the decomposition rate slows down in comparison with neat SBS. From the relation between the XPS and TG results, it can be seen that the initial thermal stability of SBS rapidly reduces as the relative concentration of the oxygen-containing groups accumulates around 3%, while the maximum decomposition temperature slowly decreases when the relative concentration of the oxygen-containing groups is more than 3%, due to the difficult damage to strong bonds on the molecular structure of aged SBS. PMID:28773124

Investigation of Molecular Structure and Thermal Properties of Thermo-Oxidative Aged SBS in Blends and Their Relations.

PubMed

Xu, Xiong; Yu, Jianying; Xue, Lihui; Zhang, Canlin; Zha, Yagang; Gu, Yi

2017-07-07

Tri-block copolymer styrene-butadiene (SBS) is extensively applied in bituminous highway construction due to its high elasticity and excellent weather resistance. With the extension of time, tri-block structural SBS automatically degrades into bi-block structural SB- with some terminal oxygen-containing groups under the comprehensive effects of light, heat, oxygen, etc. In this paper, the effects of aging temperature, aging time and oxygen concentration on the molecular structure of thermo-oxidative aged SBS were mainly investigated using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), and the correlation between oxygen-containing groups and thermal properties (TG-DTG) was further discussed. The FTIR and XPS results show that rapid decomposition of SBS will occur with increments of aging temperature, aging time and oxygen concentration, and a large number of oxygen-containing groups such as -OH, C=O, -COOH, etc. will be formed during thermo-oxidative aging. In short-term aging, changes in aging temperature and oxygen concentration have a significant impact on the structural damage of SBS. However, in long-term aging, it has no further effect on the molecular structure of SBS or on increasing oxygen concentration. The TG and DTG results indicate that the concentration of substances with low molecular weight gradually increases with the improvement of the degree of aging of the SBS, while the initial decomposition rate increases at the beginning of thermal weightlessness and the decomposition rate slows down in comparison with neat SBS. From the relation between the XPS and TG results, it can be seen that the initial thermal stability of SBS rapidly reduces as the relative concentration of the oxygen-containing groups accumulates around 3%, while the maximum decomposition temperature slowly decreases when the relative concentration of the oxygen-containing groups is more than 3%, due to the difficult damage to strong bonds on the molecular structure of aged SBS.

Oxygen permeability of the pigmented material used in cosmetic daily disposable contact lenses

PubMed Central

Galas, Stephen; Copper, Lenora L

2016-01-01

Purpose To evaluate the individual contributions of pigment colorant and packing solution containing polyvinyl pyrrolidone (PVP) on the oxygen permeability (Dk) of a cosmetic printed etafilcon A daily disposable contact lens packaged with PVP. Method The oxygen transport of a contact lens is evaluated through the central optical zone of the lens. Cosmetic printed contact lenses contain pigment colorant in the periphery or mid-periphery of the lens. Therefore, to assess the impact of cosmetic print on oxygen permeability, special lenses need to be produced that contain the colorant within the central optical zone. This technique was used to obtain multiple measurements of nonedge-corrected Dk/t of both the center pigmented lens and its nonpigmented equivalent, using a polarographic measurement described in International Organization for Standardization (ISO) 18369-4:2006(E), and the Dk derived for each measurement is corrected for edge effect. In addition, the edge-corrected Dk values of lenses made from the same monomer batch were measured. The lenses were packaged and autoclaved with and without proprietary technology which embeds PVP in the contact lens during autoclaving. The resulting Dk value of the printed lens material was then used with thickness data to generate true Dk/t profiles for a given lens power. Results The edge-corrected Dk of the printed etafilcon A lens with offset pigment colorant was measured to be 19.7×10−11 (cm2/s) (mL O2/mL·mmHg) at 35°C. This was within ±20% tolerance range as specified in ISO 18369-2:2012(E) for the edge-corrected Dk of the nonpigmented etafilcon A control lens evaluated during the same session, 19.5×10−11 (cm2/s) (mL O2/mL·mmHg). The edge-corrected Dk values of the lenses packaged with PVP (mean 20.1, standard deviation [SD] 0.3) were also within the ±20% tolerance range compared to those packaged without PVP (mean 20.0, SD 0.3). Conclusion The pigment colorant and PVP embedded in the contact lens during autoclaving were not found to influence the oxygen permeability of the etafilcon A material. PMID:28003735

Explosion characteristics of flammable organic vapors in nitrous oxide atmosphere.

PubMed

Koshiba, Yusuke; Takigawa, Tomihisa; Matsuoka, Yusaku; Ohtani, Hideo

2010-11-15

Despite unexpected explosion accidents caused by nitrous oxide have occurred, few systematic studies have been reported on explosion characteristics of flammable gases in nitrous oxide atmosphere compared to those in air or oxygen. The objective of this paper is to characterize explosion properties of mixtures of n-pentane, diethyl ether, diethylamine, or n-butyraldehyde with nitrous oxide and nitrogen using three parameters: explosion limit, peak explosion pressure, and time to the peak explosion pressure. Then, similar mixtures of n-pentane, diethyl ether, diethylamine, or n-butyraldehyde with oxygen and nitrogen were prepared to compare their explosion characteristics with the mixtures containing nitrous oxide. The explosion experiments were performed in a cylindrical vessel at atmospheric pressure and room temperature. The measurements showed that explosion ranges of the mixtures containing nitrous oxide were narrow compared to those of the mixtures containing oxygen. On the other hand, the maximum explosion pressures of the mixtures containing nitrous oxide were higher than those of the mixtures containing oxygen. Moreover, our experiments revealed that these mixtures differed in equivalence ratios at which the maximum explosion pressures were observed: the pressures of the mixtures containing nitrous oxide were observed at stoichiometry; in contrast, those of the mixtures containing oxygen were found at fuel-rich area. Chemical equilibrium calculations confirmed these behaviors. Copyright © 2010 Elsevier B.V. All rights reserved.

Drug oxygenation activities mediated by liver microsomal flavin-containing monooxygenases 1 and 3 in humans, monkeys, rats, and minipigs.

PubMed

Yamazaki, Miho; Shimizu, Makiko; Uno, Yasuhiro; Yamazaki, Hiroshi

2014-07-15

Liver microsomal flavin-containing monooxygenases (FMO, EC 1.14.13.8) 1 and 3 were functionally characterized in terms of expression levels and molecular catalytic capacities in human, cynomolgus monkey, rat, and minipig livers. Liver microsomal FMO3 in humans and monkeys and FMO1 and FMO3 in rats and minipigs could be determined immunochemically with commercially available anti-human FMO3 peptide antibodies or rat FMO1 peptide antibodies. With respect to FMO-dependent N-oxygenation of benzydamine and tozasertib and S-oxygenation of methimazole and sulindac sulfide activities, rat and minipig liver microsomes had high maximum velocity values (Vmax) and high catalytic efficiency (Vmax/Km, Michaelis constant) compared with those for human or monkey liver microsomes. Apparent Km values for recombinantly expressed rat FMO3-mediated N- and S-oxygenations were approximately 10-100-fold those of rat FMO1, although these enzymes had similar Vmax values. The mean catalytic efficiencies (Vmax/Km, 1.4 and 0.4 min(-1)μM(-1), respectively) of recombinant human and monkey FMO3 were higher than those of FMO1, whereas Vmax/Km values for rat and minipig FMO3 were low compared with those of FMO1. Minipig liver microsomal FMO1 efficiently catalyzed N- and S-oxygenation reactions; in addition, the minipig liver microsomal FMO1 concentration was higher than the levels in rats, humans, and monkeys. These results suggest that liver microsomal FMO1 could contribute to the relatively high FMO-mediated drug N- and S-oxygenation activities in rat and minipig liver microsomes and that lower expression of FMO1 in human and monkey livers could be a determinant factor for species differences in liver drug N- and S-oxygenation activities between experimental animals and humans. Copyright © 2014 Elsevier Inc. All rights reserved.

In vitro evaluation of mitochondrial dysfunction and treatment with adeno-associated virus vector in fibroblasts from Doberman Pinschers with dilated cardiomyopathy and a pyruvate dehydrogenase kinase 4 mutation.

PubMed

Sosa, Ivan; Estrada, Amara H; Winter, Brandy D; Erger, Kirsten E; Conlon, Thomas J

2016-02-01

To compare mitochondrial oxygen consumption rate (OCR) of fibroblasts from Doberman Pinschers with and without dilated cardiomyopathy (DCM) and mutation of the gene for pyruvate dehydrogenase kinase isozyme 4 (PDK4) and to evaluate in vitro whether treatment with adeno-associated virus (AAV) vector (i.e., gene therapy) would alter metabolic efficiency. 10 Doberman Pinschers screened for DCM and PDK4 mutation. PROCEDURES Fibroblasts were harvested from skin biopsy specimens obtained from Doberman Pinschers, and dogs were classified as without DCM or PDK4 mutation (n = 3) or with occult DCM and heterozygous (4) or homozygous (3) for PDK4 mutation. Fibroblasts were or were not treated with tyrosine mutant AAV type 2 vector containing PDK4 at multiplicities of infection of 1,000. Mitochondrial OCR was measured to evaluate mitochondrial metabolism. The OCR was compared among dog groups and between untreated and treated fibroblasts within groups. Mean ± SD basal OCR of fibroblasts from heterozygous (74 ± 8 pmol of O2/min) and homozygous (58 ± 12 pmol of O2/min) dogs was significantly lower than that for dogs without PDK4 mutation (115 ± 9 pmol of O2/min). After AAV transduction, OCR did not increase significantly in any group (mutation-free group, 121 ± 26 pmol of O2/min; heterozygous group, 88 ± 6 pmol of O2/min; homozygous group, 59 ± 3 pmol of O2/min). Mitochondrial function was altered in skin fibroblasts of Doberman Pinschers with DCM and PDK4 mutation. Change in mitochondrial function after in vitro gene therapy at the multiplicities of infection used in this study was not significant.

Oxidation of Carbon Fibers in a Cracked Ceramic Matrix Composite Modeled as a Function of Temperature

NASA Technical Reports Server (NTRS)

Halbig, Michael C.; Cawley, James D.; Eckel, Andrew J.

2003-01-01

The oxidation model simulates the oxidation of the reinforcing carbon fibers within a ceramic matrix composite material containing as-fabricated microcracks. The physics-based oxidation model uses theoretically and experimentally determined variables as input for the model. The model simulates the ingress of oxygen through microcracks into a two-dimensional plane within the composite material. Model input includes temperature, oxygen concentration, the reaction rate constant, the diffusion coefficient, and the crack opening width as a function of the mechanical and thermal loads. The model is run in an iterative process for a two-dimensional grid system in which oxygen diffuses through the porous and cracked regions of the material and reacts with carbon in short time steps. The model allows the local oxygen concentrations and carbon volumes from the edge to the interior of the composite to be determined over time. Oxidation damage predicted by the model was compared with that observed from microstructural analysis of experimentally tested composite material to validate the model for two temperatures of interest. When the model is run for low-temperature conditions, the kinetics are reaction controlled. Carbon and oxygen reactions occur relatively slowly. Therefore, oxygen can bypass the carbon near the outer edge and diffuse into the interior so that it saturates the entire composite at relatively high concentrations. The kinetics are limited by the reaction rate between carbon and oxygen. This results in an interior that has high local concentrations of oxygen and a similar amount of consumed carbon throughout the cross section. When the model is run for high-temperature conditions, the kinetics are diffusion controlled. Carbon and oxygen reactions occur very quickly. The carbon consumes oxygen as soon as it is supplied. The kinetics are limited by the relatively slow rate at which oxygen is supplied in comparison to the relatively fast rate at which carbon and oxygen reactions occur. This results in a sharp gradient in oxygen concentration from the edge where it is supplied to the nearest source of carbon, which is where the oxygen is quickly consumed. A moving reaction front is seen in which the outlaying carbon is consumed before the next inner layer of carbon begins to react.

Identification of Fitness Determinants during Energy-Limited Growth Arrest in Pseudomonas aeruginosa

PubMed Central

Basta, David W.; Bergkessel, Megan

2017-01-01

ABSTRACT Microbial growth arrest can be triggered by diverse factors, one of which is energy limitation due to scarcity of electron donors or acceptors. Genes that govern fitness during energy-limited growth arrest and the extent to which they overlap between different types of energy limitation are poorly defined. In this study, we exploited the fact that Pseudomonas aeruginosa can remain viable over several weeks when limited for organic carbon (pyruvate) as an electron donor or oxygen as an electron acceptor. ATP values were reduced under both types of limitation, yet more severely in the absence of oxygen. Using transposon-insertion sequencing (Tn-seq), we identified fitness determinants in these two energy-limited states. Multiple genes encoding general functions like transcriptional regulation and energy generation were required for fitness during carbon or oxygen limitation, yet many specific genes, and thus specific activities, differed in their relevance between these states. For instance, the global regulator RpoS was required during both types of energy limitation, while other global regulators such as DksA and LasR were required only during carbon or oxygen limitation, respectively. Similarly, certain ribosomal and tRNA modifications were specifically required during oxygen limitation. We validated fitness defects during energy limitation using independently generated mutants of genes detected in our screen. Mutants in distinct functional categories exhibited different fitness dynamics: regulatory genes generally manifested a phenotype early, whereas genes involved in cell wall metabolism were required later. Together, these results provide a new window into how P. aeruginosa survives growth arrest. PMID:29184024

Somatosensory evoked changes in cerebral oxygen consumption measured non-invasively in premature neonates.

PubMed

Roche-Labarbe, Nadege; Fenoglio, Angela; Radhakrishnan, Harsha; Kocienski-Filip, Marcia; Carp, Stefan A; Dubb, Jay; Boas, David A; Grant, P Ellen; Franceschini, Maria Angela

2014-01-15

The hemodynamic functional response is used as a reliable marker of neuronal activity in countless studies of brain function and cognition. In newborns and infants, however, conflicting results have appeared in the literature concerning the typical response, and there is little information on brain metabolism and functional activation. Measurement of all hemodynamic components and oxygen metabolism is critical for understanding neurovascular coupling in the developing brain. To this end, we combined multiple near infrared spectroscopy techniques to measure oxy- and deoxy-hemoglobin concentrations, cerebral blood volume (CBV), and relative cerebral blood flow (CBF) in the somatosensory cortex of 6 preterm neonates during passive tactile stimulation of the hand. By combining these measures we estimated relative changes in the cerebral metabolic rate of oxygen consumption (rCMRO2). CBF starts increasing immediately after stimulus onset, and returns to baseline before blood volume. This is consistent with the model of pre-capillary arteriole active dilation driving the CBF response, with a subsequent CBV increase influenced by capillaries and veins dilating passively to accommodate the extra blood. rCMRO2 estimated using the steady-state formulation shows a biphasic pattern: an increase immediately after stimulus onset, followed by a post-stimulus undershoot due to blood flow returning faster to baseline than oxygenation. However, assuming a longer mean transit time from the arterial to the venous compartment, due to the immature vascular system of premature infants, reduces the post-stimulus undershoot and increases the flow/consumption ratio to values closer to adult values reported in the literature. We are the first to report changes in local rCBF and rCMRO2 during functional activation in preterm infants. The ability to measure these variables in addition to hemoglobin concentration changes is critical for understanding neurovascular coupling in the developing brain, and for using this coupling as a reliable functional imaging marker in neonates. Copyright © 2013 Elsevier Inc. All rights reserved.

Fabricating niobium test loops for the SP-100 space reactor

NASA Technical Reports Server (NTRS)

Bryhan, Anthony J.; Chan, Ricky C.

1993-01-01

This article describes the successful fabrication, operation, and evaluation of a series of niobium-alloy (Nb-1 Zr and PWC-11) thermal convection loops designed to contain and circulate molten lithium at 1,350 K. These loops were used to establish the fabrication variables of significance for a nuclear power supply for space. Approximately 200 weldments were evaluated for their tendency to be attacked by lithium as a function of varying atmospheric contamination. No attack occurred for any weldment free of contamination, with or without heat treatment, and no welds accidentally deviated from purity. The threshold oxygen content for weldment attack was determined to be 170-200 ppm. Attack varied directly with weldment oxygen and nitrogen contents.

Infrared and Raman spectroscopic characterization of the carbonate bearing silicate mineral aerinite - Implications for the molecular structure

NASA Astrophysics Data System (ADS)

Frost, Ray L.; Scholz, Ricardo; López, Andrés

2015-10-01

The mineral aerinite is an interesting mineral because it contains both silicate and carbonate units which is unusual. It is also a highly colored mineral being bright blue/purple. We have studied aerinite using a combination of techniques which included scanning electron microscopy, energy dispersive X-ray analysis, Raman and infrared spectroscopy. Raman bands at 1049 and 1072 cm-1 are assigned to the carbonate symmetric stretching mode. This observation supports the concept of the non-equivalence of the carbonate units in the structure of aerinite. Multiple infrared bands at 1354, 1390 and 1450 cm-1 supports this concept. Raman bands at 933 and 974 cm-1 are assigned to silicon-oxygen stretching vibrations. Multiple hydroxyl stretching and bending vibrations show that water is in different molecular environments in the aerinite structure.

Surface pressure measurement by oxygen quenching of luminescence

NASA Technical Reports Server (NTRS)

Gouterman, Martin P. (Inventor); Kavandi, Janet L. (Inventor); Gallery, Jean (Inventor); Callis, James B. (Inventor)

1993-01-01

Methods and compositions for measuring the pressure of an oxygen-containing gas on an aerodynamic surface, by oxygen-quenching of luminescence of molecular sensors is disclosed. Objects are coated with luminescent films containing a first sensor and at least one of two additional sensors, each of the sensors having luminescences that have different dependencies on temperature and oxygen pressure. Methods and compositions are also provided for improving pressure measurements (qualitative or quantitive) on surfaces coated with a film having one or more types of sensor.

Surface pressure measurement by oxygen quenching of luminescence

NASA Technical Reports Server (NTRS)

Gouterman, Martin P. (Inventor); Kavandi, Janet L. (Inventor); Gallery, Jean (Inventor); Callis, James B. (Inventor)

1994-01-01

Methods and compositions for measuring the pressure of an oxygen-containing gas on an aerodynamic surface, by oxygen-quenching of luminescence of molecular sensors is disclosed. Objects are coated with luminescent films containing a first sensor and at least one of two additional sensors, each of the sensors having luminescences that have different dependencies on temperature and oxygen pressure. Methods and compositions are also provided for improving pressure measurements (qualitative or quantitive) on surfaces coated with a film having one or more types of sensor.

Changes in the location of biodiversity-ecosystem function hot spots across the seafloor landscape with increasing sediment nutrient loading.

PubMed

Thrush, Simon F; Hewitt, Judi E; Kraan, Casper; Lohrer, A M; Pilditch, Conrad A; Douglas, Emily

2017-04-12

Declining biodiversity and loss of ecosystem function threatens the ability of habitats to contribute ecosystem services. However, the form of the relationship between biodiversity and ecosystem function (BEF) and how relationships change with environmental change is poorly understood. This limits our ability to predict the consequences of biodiversity loss on ecosystem function, particularly in real-world marine ecosystems that are species rich, and where multiple ecosystem functions are represented by multiple indicators. We investigated spatial variation in BEF relationships across a 300 000 m 2 intertidal sandflat by nesting experimental manipulations of sediment pore water nitrogen concentration into sites with contrasting macrobenthic community composition. Our results highlight the significance of many different elements of biodiversity associated with environmental characteristics, community structure, functional diversity, ecological traits or particular species (ecosystem engineers) to important functions of coastal marine sediments (benthic oxygen consumption, ammonium pore water concentrations and flux across the sediment-water interface). Using the BEF relationships developed from our experiment, we demonstrate patchiness across a landscape in functional performance and the potential for changes in the location of functional hot and cold spots with increasing nutrient loading that have important implications for mapping and predicating change in functionality and the concomitant delivery of ecosystem services. © 2017 The Author(s).

Poly(arylene ether)s That Resist Atomic Oxygen

NASA Technical Reports Server (NTRS)

Connell, John W.; Hergenrother, Paul; Smith, Joseph G., Jr.

1994-01-01

Novel poly(arylene ether)s containing phosphine oxide (PAEPO's) made via aromatic nucleophilic displacement reactions of activated aromatic dihalides (or, in some cases, activated aromatic dinitro compounds) with new bisphenol monomers containing phosphine oxide. Exhibited favorable combination of physical and mechanical properties and resistance to monatomic oxygen in oxygen plasma environment. Useful as adhesives, coatings, films, membranes, moldings, and composite matrices.

Pyrolysis temperature influences ameliorating effects of biochars on acidic soil.

PubMed

Wan, Qing; Yuan, Jin-Hua; Xu, Ren-Kou; Li, Xing-Hui

2014-02-01

The biochars were prepared from straws of canola, corn, soybean, and peanut at different temperatures of 300, 500, and 700 °C by means of oxygen-limited pyrolysis.Amelioration effects of these biochars on an acidic Ultisol were investigated with incubation experiments, and application rate of biochars was 10 g/kg. The incorporation of these biochars induced the increase in soil pH, soil exchangeable base cations, base saturation, and cation exchange capacity and the decrease in soil exchangeable acidity and exchangeable Al. The ameliorating effects of biochars on acidic soil increased with increase in their pyrolysis temperature. The contribution of oxygen-containing functional groups on the biochars to their ameliorating effects on the acidic soil decreased with the rise in pyrolysis temperature, while the contribution from carbonates in the biochars changed oppositely. The incorporation of the biochars led to the decrease in soil reactive Al extracted by 0.5mol/L CuCl2, and the content of reactive Al was decreased with the increase in pyrolysis temperature of incorporated biochars. The biochars generated at 300 °C increased soil organically complexed Al due to ample quantity of oxygen-containing functional groups such as carboxylic and phenolic groups on the biochars, while the biochars generated at 500 and 700 °C accelerated the transformation of soil exchangeable Al to hydroxyl-Al polymers due to hydrolysis of Al at higher pH. Therefore, the crop straw-derived biochars can be used as amendments for acidic soils and the biochars generated at relatively high temperature have great ameliorating effects on the soils.

TMEM16A Contributes to Endothelial Dysfunction by Facilitating Nox2 NADPH Oxidase-Derived Reactive Oxygen Species Generation in Hypertension.

PubMed

Ma, Ming-Ming; Gao, Min; Guo, Kai-Min; Wang, Mi; Li, Xiang-Yu; Zeng, Xue-Lin; Sun, Lu; Lv, Xiao-Fei; Du, Yan-Hua; Wang, Guan-Lei; Zhou, Jia-Guo; Guan, Yong-Yuan

2017-05-01

Ca 2+ -activated Cl - channels play a crucial role in various physiological processes. However, the role of TMEM16A in vascular endothelial dysfunction during hypertension is unclear. In this study, we investigated the specific involvement of TMEM16A in regulating endothelial function and blood pressure and the underlying mechanism. Reverse transcription-polymerase chain reaction, Western blotting, coimmunoprecipitation, confocal imaging, patch-clamp recordings, and TMEM16A endothelial-specific transgenic and knockout mice were used. We found that TMEM16A was expressed abundantly and functioned as a Ca 2+ -activated Cl - channel in endothelial cells. Angiotensin II induced endothelial dysfunction with an increase in TMEM16A expression. The knockout of endothelial-specific TMEM16A significantly lowered the blood pressure and ameliorated endothelial dysfunction in angiotensin II-induced hypertension, whereas the overexpression of endothelial-specific TMEM16A resulted in the opposite effects. These results were related to the increased reactive oxygen species production, Nox2-containing NADPH oxidase activation, and Nox2 and p22phox protein expression that were facilitated by TMEM16A on angiotensin II-induced hypertensive challenge. Moreover, TMEM16A directly bound with Nox2 and reduced the degradation of Nox2 through the proteasome-dependent degradation pathway. Therefore, TMEM16A is a positive regulator of endothelial reactive oxygen species generation via Nox2-containing NADPH oxidase, which induces endothelial dysfunction and hypertension. Modification of TMEM16A may be a novel therapeutic strategy for endothelial dysfunction-associated diseases. © 2017 American Heart Association, Inc.

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

Almond, P.; Livingston, R.; Traver, L.

The Savannah River National Laboratory (SRNL) 3013 destructive examination program performs surveillances on 3013 containers originating from multiple sites across the DOE complex. The bases for the packaging, storage, and surveillance activities are derived from the Department of Energy's 3013 Standard (DOE-STD-3013-2004). During destructive examination, headspace gas samples are obtained from the 3013 inner container and the annulus between the outer and inner containers. To characterize gas species, the samples are analyzed by gas chromatography (GC), direct-inlet mass spectrometry (DIMS), and Fourier-transform infrared spectroscopy (FTIR). The GC results, as well as other parameters, are utilized as input into the gasmore » evaluation software tool (GEST) program for computation of pre-puncture gas compositions and pressures. Over 30 containers from the Hanford Site and the Rocky Flats Environmental Technology Site (RFETS) have been examined in the first three years of the surveillance program. Several containers were shown to have appreciable hydrogen content (some greater than 30 mol %), yet little or no oxygen was detected in any of the containers, including those exhibiting high hydrogen concentrations. Characteristics including moisture content, surface area, and material composition, along with the headspace gas composition, are utilized in an attempt to explain the chemical behavior of the packaged materials.« less

A 99 percent purity molecular sieve oxygen generator

NASA Technical Reports Server (NTRS)

Miller, G. W.

1991-01-01

Molecular sieve oxygen generating systems (MSOGS) have become the accepted method for the production of breathable oxygen on military aircraft. These systems separate oxygen for aircraft engine bleed air by application of pressure swing adsorption (PSA) technology. Oxygen is concentrated by preferential adsorption in nitrogen in a zeolite molecular sieve. However, the inability of current zeolite molecular sieves to discriminate between oxygen and argon results in an oxygen purity limitations of 93-95 percent (both oxygen and argon concentrate). The goal was to develop a new PSA process capable of exceeding the present oxygen purity limitations. A novel molecular sieve oxygen concentrator was developed which is capable of generating oxygen concentrations of up to 99.7 percent directly from air. The process is comprised of four absorbent beds, two containing a zeolite molecular sieve and two containing a carbon molecular sieve. This new process may find use in aircraft and medical breathing systems, and industrial air separation systems. The commercial potential of the process is currently being evaluated.

Novel clinical uses for cord blood derived mesenchymal stromal cells.

PubMed

Olson, Amanda L; McNiece, Ian K

2015-06-01

Regenerative medicine offers new hope for many debilitating diseases that result in damage to tissues and organs. The concept is straightforward with replacement of damaged cells with new functional cells. However, most tissues and organs are complex structures involving multiple cell types, supportive structures, a microenvironment producing cytokines and growth factors and a vascular system to supply oxygen and other nutrients. Therefore repair, particularly in the setting of ischemic damage, may require delivery of multiple cell types providing new vessel formation, a new microenvironment and functional cells. The field of stem cell biology has identified a number of stem cell sources including embryonic stem cells and adult stem cells that offer the potential to replace virtually all functional cells of the body. The focus of this article is a discussion of the potential of mesenchymal stromal cells (MSCs) from cord blood (CB) for regenerative medicine approaches. Copyright © 2015 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

Partitioning in Avionics Architectures: Requirements, Mechanisms, and Assurance

NASA Technical Reports Server (NTRS)

Rushby, John

1999-01-01

Automated aircraft control has traditionally been divided into distinct "functions" that are implemented separately (e.g., autopilot, autothrottle, flight management); each function has its own fault-tolerant computer system, and dependencies among different functions are generally limited to the exchange of sensor and control data. A by-product of this "federated" architecture is that faults are strongly contained within the computer system of the function where they occur and cannot readily propagate to affect the operation of other functions. More modern avionics architectures contemplate supporting multiple functions on a single, shared, fault-tolerant computer system where natural fault containment boundaries are less sharply defined. Partitioning uses appropriate hardware and software mechanisms to restore strong fault containment to such integrated architectures. This report examines the requirements for partitioning, mechanisms for their realization, and issues in providing assurance for partitioning. Because partitioning shares some concerns with computer security, security models are reviewed and compared with the concerns of partitioning.

Development of the Complex General Linear Model in the Fourier Domain: Application to fMRI Multiple Input-Output Evoked Responses for Single Subjects

PubMed Central

Rio, Daniel E.; Rawlings, Robert R.; Woltz, Lawrence A.; Gilman, Jodi; Hommer, Daniel W.

2013-01-01

A linear time-invariant model based on statistical time series analysis in the Fourier domain for single subjects is further developed and applied to functional MRI (fMRI) blood-oxygen level-dependent (BOLD) multivariate data. This methodology was originally developed to analyze multiple stimulus input evoked response BOLD data. However, to analyze clinical data generated using a repeated measures experimental design, the model has been extended to handle multivariate time series data and demonstrated on control and alcoholic subjects taken from data previously analyzed in the temporal domain. Analysis of BOLD data is typically carried out in the time domain where the data has a high temporal correlation. These analyses generally employ parametric models of the hemodynamic response function (HRF) where prewhitening of the data is attempted using autoregressive (AR) models for the noise. However, this data can be analyzed in the Fourier domain. Here, assumptions made on the noise structure are less restrictive, and hypothesis tests can be constructed based on voxel-specific nonparametric estimates of the hemodynamic transfer function (HRF in the Fourier domain). This is especially important for experimental designs involving multiple states (either stimulus or drug induced) that may alter the form of the response function. PMID:23840281

Development of the complex general linear model in the Fourier domain: application to fMRI multiple input-output evoked responses for single subjects.

PubMed

Rio, Daniel E; Rawlings, Robert R; Woltz, Lawrence A; Gilman, Jodi; Hommer, Daniel W

2013-01-01

A linear time-invariant model based on statistical time series analysis in the Fourier domain for single subjects is further developed and applied to functional MRI (fMRI) blood-oxygen level-dependent (BOLD) multivariate data. This methodology was originally developed to analyze multiple stimulus input evoked response BOLD data. However, to analyze clinical data generated using a repeated measures experimental design, the model has been extended to handle multivariate time series data and demonstrated on control and alcoholic subjects taken from data previously analyzed in the temporal domain. Analysis of BOLD data is typically carried out in the time domain where the data has a high temporal correlation. These analyses generally employ parametric models of the hemodynamic response function (HRF) where prewhitening of the data is attempted using autoregressive (AR) models for the noise. However, this data can be analyzed in the Fourier domain. Here, assumptions made on the noise structure are less restrictive, and hypothesis tests can be constructed based on voxel-specific nonparametric estimates of the hemodynamic transfer function (HRF in the Fourier domain). This is especially important for experimental designs involving multiple states (either stimulus or drug induced) that may alter the form of the response function.

Advances in Biodegradation of Multiple Volatile Organic Compounds

NASA Astrophysics Data System (ADS)

Zhang, M.; Yoshikawa, M.

2017-12-01

Bioremediation of soil and groundwater containing multiple contaminants remains a challenge in environmental science and engineering because complete biodegradation of all components is necessary but very difficult to accomplish in practice. This presentation provides a brief overview on advances in biodegradation of multiple volatile organic compounds (VOCs) including chlorinated ethylenes, benzene, toluene and dichloromethane (DCM). Case studies on aerobic biodegradation of benzene, toluene and DCM, and integrated anaerobic-aerobic biodegradation of 7 contaminants, specifically, tetrachloroethylene (PCE), trichloroethylene (TCE), cis-dichloroethylene (cis-DCE), vinyl chloride (VC), DCM, benzene and toluene will be provided. Recent findings based on systematic laboratory experiments indicated that aerobic toluene degradation can be enhanced by co-existence of benzene. Propioniferax, not a known benzene, toluene and DCM degrader can be a key microorganism that involves in biodegradation when the three contaminants co-exist. Integrated anaerobic-aerobic biodegradation is capable of completely degrading the seven VOCs with initial concentrations less than 30 mg/L. Dehalococcoides sp., generally considered sensitive to oxygen, can survive aerobic conditions for at least 28 days, and can be activated during the subsequent anaerobic biodegradation. This presentation may provide a systematic information about biodegradation of multiple VOCs, and a scientific basis for the complete bioremediation of multiple contaminants in situ.

Optical analysis of trapped Gas—Gas in Scattering Media Absorption Spectroscopy

NASA Astrophysics Data System (ADS)

Svanberg, S.

2010-01-01

An overview of the new field of Gas in Scattering Media Absorption Spectroscopy (GASMAS) is presented. The technique investigates sharp gas spectral signatures, typically 10000 times sharper than those of the host material, in which the gas is trapped in pores or cavities. The presence of pores causes strong multiple scattering. GASMAS combines narrow-band diode-laser spectroscopy, developed for atmospheric gas monitoring, with diffuse media optical propagation, well-known from biomedical optics. Several applications in materials science, food packaging, pharmaceutics and medicine have been demonstrated. So far molecular oxygen and water vapour have been studied around 760 and 935 nm, respectively. Liquid water, an important constituent in many natural materials, such as tissue, has a low absorption at such wavelengths, and this is also true for haemoglobin, making propagation possible in many natural materials. Polystyrene foam, wood, fruits, food-stuffs, pharmaceutical tablets, and human sinus cavities (frontal, maxillary and mastoideal) have been studied, demonstrating new possibilities for characterization and diagnostics. Transport of gas in porous media (diffusion) can be studied by first subjecting the material to, e.g., pure nitrogen, and then observing the rate at which normal, oxygen-containing air, reinvades the material. The conductance of the passages connecting a sinus with the nasal cavity can be objectively assessed by observing the oxygen gas dynamics when flushing the nose with nitrogen. Drying of materials, when liquid water is replaced by air and water vapour, is another example of dynamic processes which can be studied. The technique has also been extended to remote-sensing applications (LIDAR-GASMAS or Multiple-Scattering LIDAR).

Use of a micro programmable logic controller for oxygen monitoring and control in multiple tanks of a recirculating aquaculture system

USDA-ARS?s Scientific Manuscript database

In intensive recirculating aquaculture systems the use of supplemental oxygen, specifically pure liquid oxygen, increases the mass of fish that can be supported and eliminates oxygen as a major limiting factor to a system’s carrying capacity. The use of pure oxygen in a recirculating aquaculture sys...

Impact of dia- and catagenesis on sulphur and oxygen sequestration of biomarkers as revealed by artificial maturation of an immature sedimentary rock

USGS Publications Warehouse

Koopmans, M.P.; De Leeuw, J. W.; Lewan, M.D.; Sinninghe, Damste J.S.

1996-01-01

Hydrous pyrolysis of an immature (R(a)??? 0.25%) sulphur-rich marl from the Gessoso-solfifera Formation (Messinian) in the Vena del Gesso Basin was carried out at 160C ??? T ???330 C for 72 h, to study the effect of progressive diagenesis and early catagenesis on the abundance and distribution of sulphur-containing and sulphur- and oxygen-linked carbon skeletons in low-molecular-weight and highmolecular-weight fractions (e.g. kerogen). To this end, compounds in the saturated hydrocarbon fraction, monoaromatic hydrocarbon fraction, polyaromatic hydrocarbon fraction, alkylsulphide fraction and ketone fraction were quantified, as well as compounds released after desulphurisation of the polar fraction and HI/LiAIH4 treatment of the desulphurised polar fraction. Sulphur-bound phytane and (20R)-5??,14??,17??(H) and (20R)-5??,14??,17??(H) C27 C29 steranes in the polar fraction become less abundant with increasing maturation temperature, whereas the amount of their corresponding hydrocarbons increases in the saturated hydrocarbon fraction. Carbon skeletons that are bound in the kerogen by multiple bonds (e.g. C38 n-alkane and isorenieratane) are first released into the polar fraction, and then as free hydrocarbons. These changes occur at relatively low levels of thermal maturity (R(a) <0.6%), as evidenced by the 'immature' values of biomarker maturity parameters such as the ????/(????+ ???? + ????) C35 hopane ratio and the 22S/(22S + 22R)-17??,21??(H) C35 hopane ratio. Sulphur- and oxygen-bound moieties, present in the polar fraction, are not stable with increasing thermal maturation. However, alkylthiophenes, ketones. 1,2-di-n-alkylbenzenes and free n-alkanes seem to be stable thermal degradation products of these sulphur- and oxygen-bound moieties. Thus, apart from free n-alkanes, which are abundantly present in more mature sedimentary rocks and crude oils, alkylthiophenes, 1,2-di-n-alkylbenzenes and ketones can also be expected to occur. The positions of the thiophene moiety and the carbonyl group coincide with the original positions of the functional groups of their precursors. Thus, important information about palaeobiochemicals is retained throughout the sequestration/degradation process.

FnrL and Three Dnr Regulators Are Used for the Metabolic Adaptation to Low Oxygen Tension in Dinoroseobacter shibae

PubMed Central

Ebert, Matthias; Laaß, Sebastian; Thürmer, Andrea; Roselius, Louisa; Eckweiler, Denitsa; Daniel, Rolf; Härtig, Elisabeth; Jahn, Dieter

2017-01-01

The heterotrophic marine bacterium Dinoroseobacter shibae utilizes aerobic respiration and anaerobic denitrification supplemented with aerobic anoxygenic photosynthesis for energy generation. The aerobic to anaerobic transition is controlled by four Fnr/Crp family regulators in a unique cascade-type regulatory network. FnrL is utilizing an oxygen-sensitive Fe-S cluster for oxygen sensing. Active FnrL is inducing most operons encoding the denitrification machinery and the corresponding heme biosynthesis. Activation of gene expression of the high oxygen affinity cbb3-type and repression of the low affinity aa3-type cytochrome c oxidase is mediated by FnrL. Five regulator genes including dnrE and dnrF are directly controlled by FnrL. Multiple genes of the universal stress protein (USP) and cold shock response are further FnrL targets. DnrD, most likely sensing NO via a heme cofactor, co-induces genes of denitrification, heme biosynthesis, and the regulator genes dnrE and dnrF. DnrE is controlling genes for a putative Na+/H+ antiporter, indicating a potential role of a Na+ gradient under anaerobic conditions. The formation of the electron donating primary dehydrogenases is coordinated by FnrL and DnrE. Many plasmid encoded genes were DnrE regulated. DnrF is controlling directly two regulator genes including the Fe-S cluster biosynthesis regulator iscR, genes of the electron transport chain and the glutathione metabolism. The genes for nitrate reductase and CO dehydrogenase are repressed by DnrD and DnrF. Both regulators in concert with FnrL are inducing the photosynthesis genes. One of the major denitrification operon control regions, the intergenic region between nirS and nosR2, contains one Fnr/Dnr binding site. Using regulator gene mutant strains, lacZ-reporter gene fusions in combination with promoter mutagenesis, the function of the single Fnr/Dnr binding site for FnrL-, DnrD-, and partly DnrF-dependent nirS and nosR2 transcriptional activation was shown. Overall, the unique regulatory network of the marine bacterium D. shibae for the transition from aerobic to anaerobic growth composed of four Crp/Fnr family regulators was elucidated. PMID:28473807

Effects of Surface Oxygen on the Performance of Carbon as an Anode in Lithium-Ion Batteries

NASA Technical Reports Server (NTRS)

Hung, Ching-Cheh; Clark, Gregory W.

2001-01-01

Carbon materials with similar bulk structure but different surface oxygen were compared for their performance as anodes in lithium-ion battery. The bulk structure was such that the graphene planes were perpendicular to the surface. Three types of surfaces were examined: surface containing C=O type oxygen. surface containing -O-C type oxygen, and surface containing high concentration of active sites. The test involved cycles of lithium insertion into and release from the carbon materials, which was in the half cells of carbon/saturated LiI-50/50 (vol %) EC and DMC/lithium. During the first cycle of lithium insertion, the presence of adsorbed oxygen, -O-C type oxygen, active carbon sites, and C=O type oxygen resulted in the formation of solid-electrolyte interface (SEI) when the carbon's voltage relative to lithium metal was >1.35, 1 to 1.35, 0.5 to 1, and 0.67 to 0.7 V, respectively. An optimum -O-C type oxygen and a minimum C=O type oxygen was found to increase the reversible and decrease the irreversible capacity of carbon. Active sites on the carbon surface result in a large irreversible capacity and a second lithium insertion-release mechanism. However, this new mechanism has a short cycle life.

Effect of pre-pyrolysis mode on simultaneous introduction of nitrogen/oxygen-containing functional groups into the structure of bagasse-based mesoporous carbon and its influence on Cu(II) adsorption.

PubMed

Wan, Zeqing; Li, Kunquan

2018-03-01

A convenient effective microwave pre-pyrolysis treatment to synthesize biomass-based mesoporous carbon with higher nitrogen/oxygen-chelating adsorption for Cu(II) is reported here, in which phosphoric acid impregnated bagasse was used as a microwave absorber and porogen. For comparison, conventional electric-heating pyrolyzed carbon was prepared and doped with nitrogen/oxygen groups. Nitrogen adsorption, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy (XPS) and batch adsorption were employed to investigate the effects of the two pre-pyrolysis modes on the sample physicochemical and Cu(II) adsorptive properties. The 22-min-microwave-pyrolyzed bagasse mesoporous activated carbon (MBAC, 85.32% mesoporosity) contained 10.52% O, which is 3.94% more than electric-heating pyrolyzed mesoporous activated carbon (89.52% mesoporosity). After electrophilic aromatic substitutions of N/O doping, the former possessed more N (5.83%) and more O (21.40%), confirming that time-saving energy-efficient microwave pyrolysis favors the formation of defective C/O atoms in or at the edges of the graphite layer of MBAC, which are highly active and tend to act as preferred reactive positions for the doping of N/O-containing groups simultaneously compared with conventional electric-heating pyrolysis. These N and O species existed mainly as COOH, OH, NH and NH 2 functional groups, and were confirmed by XPS to be active sites for metal binding via electrostatic attraction, hydrogen bonding, a chelate effect and complexation, resulting in the great enhancement of Cu(II) adsorption. Langmuir isotherm and pseudo-second-order kinetic fitting further proved that Cu(II) adsorption by N/O-doped MBAC is ascribed mainly to chemisorption. Therefore, rapid microwave pre-pyrolysis provides a promising route to prepare excellent-performance N/O-doped carbon adsorbents. Copyright © 2017 Elsevier Ltd. All rights reserved.

Time-Dependent Behavior of Microvascular Blood Flow and Oxygenation: A Predictor of Functional Outcomes.

PubMed

Kuliga, Katarzyna Z; Gush, Rodney; Clough, Geraldine F; Chipperfield, Andrew John

2018-05-01

This study investigates the time-dependent behaviour and algorithmic complexity of low-frequency periodic oscillations in blood flux (BF) and oxygenation signals from the microvasculature. Microvascular BF and oxygenation (OXY: oxyHb, deoxyHb, totalHb, and SO 2 %) was recorded from 15 healthy young adult males using combined laser Doppler fluximetry and white light spectroscopy with local skin temperature clamped to 33  °C and during local thermal hyperaemia (LTH) at 43 °C. Power spectral density of the BF and OXY signals was evaluated within the frequency range (0.0095-1.6 Hz). Signal complexity was determined using the Lempel-Ziv (LZ) algorithm. Fold increase in BF during LTH was 15.6 (10.3, 22.8) and in OxyHb 4.8 (3.5, 5.9) (median, range). All BF and OXY signals exhibited multiple oscillatory components with clear differences in signal power distribution across frequency bands at 33 and 43 °C. Significant reduction in the intrinsic variability and complexity of the microvascular signals during LTH was found, with mean LZ complexity of BF and OxyHb falling by 25% and 49%, respectively ( ). These results provide corroboration that in human skin microvascular blood flow and oxygenation are influenced by multiple time-varying oscillators that adapt to local influences and become more predictable during increased haemodynamic flow. Recent evidence strongly suggests that the inability of microvascular networks to adapt to an imposed stressor is symptomatic of disease risk which might be assessed via BF and OXY via the combination signal analysis techniques described here.

A multiple p-n junction structure obtained from as-grown Czochralski silicon crystals by heat treatment - Application to solar cells

NASA Technical Reports Server (NTRS)

Chi, J. Y.; Gatos, H. C.; Mao, B. Y.

1980-01-01

Multiple p-n junctions have been prepared in as-grown Czochralski p-type silicon through overcompensation near the oxygen periodic concentration maxima by oxygen thermal donors generated during heat treatment at 450 C. Application of the multiple p-n-junction configuration to photovoltaic energy conversion has been investigated. A new solar-cell structure based on multiple p-n-junctions was developed. Theoretical analysis showed that a significant increase in collection efficiency over the conventional solar cells can be achieved.

Toward highly efficient electrocatalyst for Li–O 2 batteries using biphasic N-doping cobalt@graphene multiple-capsule heterostructures

DOE PAGES

Tan, Guoqiang; Chong, Lina; Amine, Rachid; ...

2017-04-12

To promote lithium-oxygen batteries available for practical applications, the development of advanced cathode catalysts with low-cost, high activity and stable structural properties is demanded. Such development is rooted on certain intelligent catalyst-electrode design that fundamentally facilitates electronic and ionic transport, and improves oxygen diffusivity in a porous environment. Here we design a biphasic nitrogen-doped cobalt@graphene multiple-capsule heterostructure, combined with a flexible, stable porous electrode architecture, and apply it as promising cathodes for lithium-oxygen cells. The biphasic nitrogen-doping feature improves the electric conductivity and catalytic activity; the multiple-nanocapsule configuration makes high/uniform electro-active zones possible; furthermore, the colander-like porous electrode facilitates themore » oxygen diffusion, catalytic reaction, and stable deposition of discharge products. Finally, the electrode exhibits much improved electrocatalytic properties associated with unique morphologies of electrochemically grown lithium peroxides.« less

Toward Highly Efficient Electrocatalyst for Li–O 2 Batteries Using Biphasic N-Doping Cobalt@Graphene Multiple-Capsule Heterostructures

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

Tan, Guoqiang; Chong, Lina; Amine, Rachid

For the promotion of lithium oxygen batteries available for :practical applications, the development of advanced cathode catalysts with low-high activity, and stable structural properties is demanded. Such development is rooted on certain intelligent catalyst-electrode design that fundamentally facilitates electronic and ionic transport and improves oxygen diffusivity in a porous environment. Here we design a biphasic nitrogen-doped cobalt@grapbene Multiple-capsule heterostructure, combined with a flexible, stable porous electrode architecture, and apply it as promising cathodes for lithium oxygen cells. 'The biphasic nitrogen-doping feature improves the electric conductivity and catalytic activity; the multiple-nanocapsule configuration makes high/uniform electroactive zones possible; furthermore the colander-like porousmore » electrode facilitates the oxygen diffusion, catalytic reaction,and stable deposition of discharge products. As a result, the electrode exhibits much improved electrocatalytic properties associated with unique morphologies of electrochemically grown lithium peroxides.« less

Toward highly efficient electrocatalyst for Li–O 2 batteries using biphasic N-doping cobalt@graphene multiple-capsule heterostructures

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

Tan, Guoqiang; Chong, Lina; Amine, Rachid

To promote lithium-oxygen batteries available for practical applications, the development of advanced cathode catalysts with low-cost, high activity and stable structural properties is demanded. Such development is rooted on certain intelligent catalyst-electrode design that fundamentally facilitates electronic and ionic transport, and improves oxygen diffusivity in a porous environment. Here we design a biphasic nitrogen-doped cobalt@graphene multiple-capsule heterostructure, combined with a flexible, stable porous electrode architecture, and apply it as promising cathodes for lithium-oxygen cells. The biphasic nitrogen-doping feature improves the electric conductivity and catalytic activity; the multiple-nanocapsule configuration makes high/uniform electro-active zones possible; furthermore, the colander-like porous electrode facilitates themore » oxygen diffusion, catalytic reaction, and stable deposition of discharge products. Finally, the electrode exhibits much improved electrocatalytic properties associated with unique morphologies of electrochemically grown lithium peroxides.« less

Toward Highly Efficient Electrocatalyst for Li-O2 Batteries Using Biphasic N-Doping Cobalt@Graphene Multiple-Capsule Heterostructures.

PubMed

Tan, Guoqiang; Chong, Lina; Amine, Rachid; Lu, Jun; Liu, Cong; Yuan, Yifei; Wen, Jianguo; He, Kun; Bi, Xuanxuan; Guo, Yuanyuan; Wang, Hsien-Hau; Shahbazian-Yassar, Reza; Al Hallaj, Said; Miller, Dean J; Liu, Dijia; Amine, Khalil

2017-05-10

For the promotion of lithium-oxygen batteries available for practical applications, the development of advanced cathode catalysts with low-cost, high activity, and stable structural properties is demanded. Such development is rooted on certain intelligent catalyst-electrode design that fundamentally facilitates electronic and ionic transport and improves oxygen diffusivity in a porous environment. Here we design a biphasic nitrogen-doped cobalt@graphene multiple-capsule heterostructure, combined with a flexible, stable porous electrode architecture, and apply it as promising cathodes for lithium-oxygen cells. The biphasic nitrogen-doping feature improves the electric conductivity and catalytic activity; the multiple-nanocapsule configuration makes high/uniform electroactive zones possible; furthermore, the colander-like porous electrode facilitates the oxygen diffusion, catalytic reaction, and stable deposition of discharge products. As a result, the electrode exhibits much improved electrocatalytic properties associated with unique morphologies of electrochemically grown lithium peroxides.

Oxygen Reduction Reaction on Ag(111) in Alkaline Solution: A Combined Density Functional Theory and Kinetic Monte Carlo Study

DOE PAGES

Liu, Shizhong; White, Michael G.; Liu, Ping

2018-01-25

We reported a detailed mechanistic study of the oxygen reduction reaction (ORR) on the model Ag(111) surface in alkaline solution by using density functional theory (DFT) and Kinetic Monte Carlo (KMC) simulations, in which multiple pathways involving either 2 e - or 4 e - mechanisms were included. The theoretical modelling presented here is able to reproduce the experimentally measured polarization curves in both low and high potential regions. An electrochemical 4 e - network including both a chemisorbed water (*H 2O)-mediated 4 e - associative pathway and the conventional associative pathway was identified to dominate the ORR mechanism. Onmore » the basis of the mechanistic understanding derived from these calculations, the ways to promote the ORR on Ag(111) were provided, including facilitating *OH removal, **O 2 reduction by *H 2O, and suppressing **O 2 desorption. Finally, the origin of the different ORR behaviors of Ag(111) and Pt(111) was also discussed in detail.« less

Oxygen Reduction Reaction on Ag(111) in Alkaline Solution: A Combined Density Functional Theory and Kinetic Monte Carlo Study

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

Liu, Shizhong; White, Michael G.; Liu, Ping

We reported a detailed mechanistic study of the oxygen reduction reaction (ORR) on the model Ag(111) surface in alkaline solution by using density functional theory (DFT) and Kinetic Monte Carlo (KMC) simulations, in which multiple pathways involving either 2 e - or 4 e - mechanisms were included. The theoretical modelling presented here is able to reproduce the experimentally measured polarization curves in both low and high potential regions. An electrochemical 4 e - network including both a chemisorbed water (*H 2O)-mediated 4 e - associative pathway and the conventional associative pathway was identified to dominate the ORR mechanism. Onmore » the basis of the mechanistic understanding derived from these calculations, the ways to promote the ORR on Ag(111) were provided, including facilitating *OH removal, **O 2 reduction by *H 2O, and suppressing **O 2 desorption. Finally, the origin of the different ORR behaviors of Ag(111) and Pt(111) was also discussed in detail.« less

Tunable catalytic properties of bi-functional mixed oxides in ethanol conversion to high value compounds

DOE PAGES

Ramasamy, Karthikeyan K.; Gray, Michel; Job, Heather; ...

2016-02-03

Here, a highly versatile ethanol conversion process to selectively generate high value compounds is presented here. By changing the reaction temperature, ethanol can be selectively converted to >C 2 alcohols/oxygenates or phenolic compounds over hydrotalcite derived bi-functional MgO–Al 2O 3 catalyst via complex cascade mechanism. Reaction temperature plays a role in whether aldol condensation or the acetone formation is the path taken in changing the product composition. This article contains the catalytic activity comparison between the mono-functional and physical mixture counterpart to the hydrotalcite derived mixed oxides and the detailed discussion on the reaction mechanisms.

Insights into the Function of a Second, Nonclassical Ahp Peroxidase, AhpA, in Oxidative Stress Resistance in Bacillus subtilis

PubMed Central

Broden, Nicole J.; Flury, Sarah; King, Alyssa N.; Schroeder, Braden W.; Coe, Gabrielle Dierker

2016-01-01

ABSTRACT Organisms growing aerobically generate reactive oxygen-containing molecules, such as hydrogen peroxide (H2O2). These reactive oxygen molecules damage enzymes and DNA and may even cause cell death. In response, Bacillus subtilis produces at least nine potential peroxide-scavenging enzymes, two of which appear to be the primary enzymes responsible for detoxifying peroxides during vegetative growth: a catalase (encoded by katA) and an alkylhydroperoxide reductase (Ahp, encoded by ahpC). AhpC uses two redox-active cysteine residues to reduce peroxides to nontoxic molecules. A specialized thioredoxin-like protein, AhpF, is then required to restore oxidized AhpC back to its reduced state. Curiously, B. subtilis has two genes encoding Ahp: ahpC and ahpA. Although AhpC is well characterized, very little is known about AhpA. In fact, numerous bacterial species have multiple ahp genes; however, these additional Ahp proteins are generally uncharacterized. We seek to understand the role of AhpA in the bacterium's defense against toxic peroxide molecules in relation to the roles previously assigned to AhpC and catalase. Our results demonstrate that AhpA has catalytic activity similar to that of the primary enzyme, AhpC. Furthermore, our results suggest that a unique thioredoxin redox protein, AhpT, may reduce AhpA upon its oxidation by peroxides. However, unlike AhpC, which is expressed well during vegetative growth, our results suggest that AhpA is expressed primarily during postexponential growth. IMPORTANCE B. subtilis appears to produce nine enzymes designed to protect cells against peroxides; two belong to the Ahp class of peroxidases. These studies provide an initial characterization of one of these Ahp homologs and demonstrate that the two Ahp enzymes are not simply replicates of each other, suggesting that they instead are expressed at different times during growth of the cells. These results highlight the need to further study the Ahp homologs to better understand how they differ from one another and to identify their function, if any, in protection against oxidative stress. Through these studies, we may better understand why bacteria have multiple enzymes designed to scavenge peroxides and thus have a more accurate understanding of oxidative stress resistance. PMID:26787766

Plant for producing an oxygen-containing additive as an ecologically beneficial component for liquid motor fuels

DOEpatents

Siryk, Yury Paul; Balytski, Ivan Peter; Korolyov, Volodymyr George; Klishyn, Olexiy Nick; Lnianiy, Vitaly Nick; Lyakh, Yury Alex; Rogulin, Victor Valery

2013-04-30

A plant for producing an oxygen-containing additive for liquid motor fuels comprises an anaerobic fermentation vessel, a gasholder, a system for removal of sulphuretted hydrogen, and a hotwell. The plant further comprises an aerobic fermentation vessel, a device for liquid substance pumping, a device for liquid aeration with an oxygen-containing gas, a removal system of solid mass residue after fermentation, a gas distribution device; a device for heavy gases utilization; a device for ammonia adsorption by water; a liquid-gas mixer; a cavity mixer, a system that serves superficial active and dispersant matters and a cooler; all of these being connected to each other by pipelines. The technical result being the implementation of a process for producing an oxygen containing additive, which after being added to liquid motor fuels, provides an ecologically beneficial component for motor fuels by ensuring the stability of composition fuel properties during long-term storage.

Discovery and Characterization of a Pourbaix-Stable, 1.8 eV Direct Gap Bismuth Manganate Photoanode

DOE PAGES

Newhouse, Paul F.; Reyes-Lillo, Sebastian E.; Li, Guo; ...

2017-11-13

Solar-driven oxygen evolution is a critical technology for renewably synthesizing hydrogen- and carbon-containing fuels in solar fuel generators. New photoanode materials are needed to meet efficiency and stability requirements, motivating materials explorations for semiconductors with (i) band-gap energy in the visible spectrum and (ii) stable operation in aqueous electrolyte at the electrochemical potential needed to evolve oxygen from water. Motivated by the oxygen evolution competency of many Mn-based oxides, the existence of several Bi-containing ternary oxide photoanode materials, and the variety of known oxide materials combining these elements with Sm, we explore the Bi-Mn-Sm oxide system for new photoanodes. Throughmore » the use of a ferri/ferrocyanide redox couple in high-throughput screening, BiMn 2O 5 and its alloy with Sm are identified as photoanode materials with a near-ideal optical band gap of 1.8 eV. Using density functional theory-based calculations of the mullite Bi 3+ Mn 3+ Mn 4+O 5 phase, we identify electronic analogues to the well-known BiVO 4 photoanode and demonstrate excellent Pourbaix stability above the oxygen evolution Nernstian potential from pH 4.5 to 15. Lastly, our suite of experimental and computational characterization indicates that BiMn 2O 5 is a complex oxide with the necessary optical and chemical properties to be an efficient, stable solar fuel photoanode.« less

Discovery and Characterization of a Pourbaix-Stable, 1.8 eV Direct Gap Bismuth Manganate Photoanode

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

Newhouse, Paul F.; Reyes-Lillo, Sebastian E.; Li, Guo

Solar-driven oxygen evolution is a critical technology for renewably synthesizing hydrogen- and carbon-containing fuels in solar fuel generators. New photoanode materials are needed to meet efficiency and stability requirements, motivating materials explorations for semiconductors with (i) band-gap energy in the visible spectrum and (ii) stable operation in aqueous electrolyte at the electrochemical potential needed to evolve oxygen from water. Motivated by the oxygen evolution competency of many Mn-based oxides, the existence of several Bi-containing ternary oxide photoanode materials, and the variety of known oxide materials combining these elements with Sm, we explore the Bi-Mn-Sm oxide system for new photoanodes. Throughmore » the use of a ferri/ferrocyanide redox couple in high-throughput screening, BiMn 2O 5 and its alloy with Sm are identified as photoanode materials with a near-ideal optical band gap of 1.8 eV. Using density functional theory-based calculations of the mullite Bi 3+ Mn 3+ Mn 4+O 5 phase, we identify electronic analogues to the well-known BiVO 4 photoanode and demonstrate excellent Pourbaix stability above the oxygen evolution Nernstian potential from pH 4.5 to 15. Lastly, our suite of experimental and computational characterization indicates that BiMn 2O 5 is a complex oxide with the necessary optical and chemical properties to be an efficient, stable solar fuel photoanode.« less

Spectrum and mechanisms of inflammasome activation by chitosan.

PubMed

Bueter, Chelsea L; Lee, Chrono K; Wang, Jennifer P; Ostroff, Gary R; Specht, Charles A; Levitz, Stuart M

2014-06-15

Chitosan, the deacetylated derivative of chitin, can be found in the cell wall of some fungi and is used in translational applications. We have shown that highly purified preparations of chitosan, but not chitin, activate the NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome in primed mouse bone marrow-derived macrophages (BMMΦ), inducing a robust IL-1β response. In this article, we further define specific cell types that are activated and delineate mechanisms of activation. BMMΦ differentiated to promote a classically activated (M1) phenotype released more IL-1β in response to chitosan than intermediate or alternatively activated macrophages (M2). Chitosan, but not chitin, induced a robust IL-1β response in mouse dendritic cells, peritoneal macrophages, and human PBMCs. Three mechanisms for NLRP3 inflammasome activation may contribute: K(+) efflux, reactive oxygen species, and lysosomal destabilization. The contributions of these mechanisms were tested using a K(+) efflux inhibitor, high extracellular potassium, a mitochondrial reactive oxygen species inhibitor, lysosomal acidification inhibitors, and a cathepsin B inhibitor. These studies revealed that each of these pathways participated in optimal NLRP3 inflammasome activation by chitosan. Finally, neither chitosan nor chitin stimulated significant release from unprimed BMMΦ of any of 22 cytokines and chemokines assayed. This study has the following conclusions: 1) chitosan, but not chitin, stimulates IL-1β release from multiple murine and human cell types; 2) multiple nonredundant mechanisms appear to participate in inflammasome activation by chitosan; and 3) chitin and chitosan are relatively weak stimulators of inflammatory mediators from unprimed BMMΦ. These data have implications for understanding the nature of the immune response to microbes and biomaterials that contain chitin and chitosan. Copyright © 2014 by The American Association of Immunologists, Inc.

Sunlight-Triggered Nanoparticle Synergy: Teamwork of Reactive Oxygen Species and Nitric Oxide Released from Mesoporous Organosilica with Advanced Antibacterial Activity.

PubMed

Gehring, Julia; Trepka, Bastian; Klinkenberg, Nele; Bronner, Hannah; Schleheck, David; Polarz, Sebastian

2016-03-09

Colonization of surfaces by microorganisms is an urging problem. In combination with the increasing antibiotic resistance of pathogenic bacteria, severe infections are reported more frequently in medical settings. Therefore, there is a large demand to explore innovative surface coatings that provide intrinsic and highly effective antibacterial activity. Materials containing silver nanoparticles have been developed in the past for this purpose, but this solution has come into criticism due to various disadvantages like notable toxicity against higher organisms, the high price, and low abundance of silver. Here, we introduce a new, sunlight-mediated organosilica nanoparticle (NP) system based on silver-free antibacterial activity. The simultaneous release of nitric oxide (NO) in combination with singlet oxygen and superoxide radicals (O2(•-)) as reactive oxygen species (ROS) leads to the emergence of highly reactive peroxynitrite molecules with significantly enhanced biocidal activity. This special cooperative effect can only be realized, if the ROS-producing moieties and the functional entities releasing NO are spatially separated from each other. In one type of particle, Rose Bengal as an efficient singlet oxygen ((1)O2) producer was covalently bound to SH functionalities applying thiol-ene click chemistry. "Charging" the second type of particles with NO was realized by quantitatively transferring the thiol groups into S-nitrosothiol functionalities. We probed the oxidation power of ROS-NP alone and in combination with NO-NP using sunlight as a trigger. The high antibacterial efficiency of dual-action nanoparticles was demonstrated using disinfection assays with the pathogenic bacterium Pseudomonas aeruginosa.

Pesticides water decontamination in oxygen-limited conditions.

PubMed

Suciu, Nicoleta Alina; Ferrari, Federico; Vasileiadis, Sotirios; Merli, Annalisa; Capri, Ettore; Trevisan, Marco

2013-01-01

This study was undertaken to develop a laboratory bioreactor, with a functioning principle similar with that of biobed systems but working in oxygen-limited conditions, suitable for decontaminating wastewater mixtures with pesticides. The system is composed by two cylindrical plastic containers. The first one, where the pesticides solution is collected, is open, whereas the second one, where the biomass is disposed, is closed. The pesticides solution was pumped at the biomass surface and subsequently recollected and disposed in the first container. Four pesticides with different physical-chemical characteristics were tested. The results obtained showed a relatively good capacity of the developed prototype to decontaminate waste water containing the mixture of pesticides. The time of the experiment, the number of cycles that the solution made in the system and the environmental temperature have a significantly influence for the decontamination of acetochlor and chlorpyrifos whereas for the decontamination of terbuthylazine and metalaxyl no significant influence was observed. Even if the present prototype could represent a valid solution to manage the water pesticides residues in a farm and to increase the confidence of bystanders and residents, the practical difficulties when replacing the biomass could represent a limit of the system.

Nanostructured fluorescent particles for glucose sensing

NASA Astrophysics Data System (ADS)

Grant, Patrick S.; Fang, Ming; Lvov, Yuri; McShane, Michael J.

2002-05-01

Self-assembled thin films containing embedded enzymes and fluorescent indicators are being developed for use as highly specific glucose biosensors. The sensors are fabricated using electrostatic Layer-by-Layer (LBL) adsorption to create oxygen-sensitive (Ruthenium-based) layers, the fluorescent intensity of which responds to changes in local oxygen levels. Oxygen is consumed locally by the reaction between glucose oxidase (GOx) molecules and glucose. Latex particles serve as the templates for our sensors and fabrication is carried out through the alternate adsorption of multiple levels of {GOx/polycation} and {Ruthenium-polycation/polyanion} bilayers. Additional fluorescence layers as well as fluorescent latex are being considered as internal intensity references to allow ratiometric monitoring. Films adsorbed to the nanoparticle templates are being studied to understand the fundamental chemical and optical properties, including enzymatic activity, spectral shape and emission intensity. Enzymatic activity is retained and stability is improved after adsorption, and increased surface area afforded by the particles allows use of increased numbers of molecules. Fluorescence is also maintained, though blue shifts are observed in emission spectra, and indicator activity remains. In vitro characterization studies demonstrate the feasibility of the particles as glucose biosensors, and future work will aim to optimize the response for neural monitoring.

Structural evaluation of reduced graphene oxide in graphene oxide during ion irradiation: X-ray absorption spectroscopy and in-situ sheet resistance studies

NASA Astrophysics Data System (ADS)

Saravanan, K.; Jayalakshmi, G.; Suresh, K.; Sundaravel, B.; Panigrahi, B. K.; Phase, D. M.

2018-03-01

We report the structural evolution of reduced graphene oxide (rGO) in graphene oxide (GO) flakes during 1 MeV Si+ ion irradiation. In-situ electrical resistivity measurements facilitate monitoring the sheet resistance with the increase in the fluence. The electrical sheet resistance of the GO flake shows the exponential decay behaviour with the increasing ion fluence. Raman spectra of the GO flake reveal the increase in the ID/IG ratio, indicating restoration of the sp2 network upon irradiation. The C/O ratio estimated from resonant Rutherford backscattering spectrometry analysis directly evidenced the reduction of oxygen moieties upon irradiation. C K-edge X-ray absorption near edge structure spectra reveal the restoration of C=C sp2-hybridized carbon atoms and the removal of oxygen-containing functional groups in the GO flake. STM data reveal the higher conductance in the rGO regime in comparison with the regime, where the oxygen functional groups are present. The experimental investigation demonstrates that the ion irradiation can be employed for efficient reduction of GO with tunable electrical and structural properties.

Graphene Oxide Catalyzed C-H Bond Activation: The Importance Oxygen Functional Groups for Biaryl Construction

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

Gao, Yongjun; Tang, Pei; Zhou, Hu

A heterogeneous, inexpensive and environment-friendly carbon catalytic system was developed for the C-H bond arylation of benzene resulting in the subsequent formation of biaryl compounds. The oxygen-containing groups on these graphene oxide sheets play an essential role in the observed catalytic activity. The catalytic results of model compounds and DFT calculations show that these functional groups promote this reaction by stabilization and activation of K ions at the same time of facilitating the leaving of I. And further mechanisms studies show that it is the charge induced capabilities of oxygen groups connected to specific carbon skeleton together with the giantmore » π-reaction platform provided by the π-domain of graphene that played the vital roles in the observed excellent catalytic activity. D. Mei acknowledges the support from the US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. Computing time was granted by the grand challenge of computational catalysis of the William R. Wiley Environmental Molecular Sciences Laboratory.« less

Aerobic function in mitochondria persists beyond death by heat stress in insects.

PubMed

Heinrich, Erica C; Gray, Emilie M; Ossher, Ashley; Meigher, Stephen; Grun, Felix; Bradley, Timothy J

2017-10-01

The critical thermal maximum (CT max ) of insects can be determined using flow-through thermolimit respirometry. It has been demonstrated that respiratory patterns cease and insects do not recover once the CT max temperature has been reached. However, if high temperatures are maintained following the CT max , researchers have observed a curious phenomenon whereby the insect body releases a large burst of carbon dioxide at a rate and magnitude that often exceed that of the live insect. This carbon dioxide release has been termed the post-mortal peak (PMP). We demonstrate here that the PMP is observed only at high temperatures, is oxygen-dependent, is prevented by cyanide exposure, and is associated with concomitant consumption of oxygen. We conclude that the PMP derives from highly active, aerobic metabolism in the mitochondria. The insect tracheal system contains air-filled tubes that reach deep into the tissues and allow mitochondria access to oxygen even upon organismal death. This unique condition permits the investigation of mitochondrial function during thermal failure in a manner that cannot be achieved using vertebrate organisms or in vitro preparations. Copyright © 2017 Elsevier Ltd. All rights reserved.

Formation and emission of large furans and oxygenated hydrocarbons from flames

PubMed Central

Johansson, K. Olof; Dillstrom, Tyler; Monti, Matteo; El Gabaly, Farid; Campbell, Matthew F.; Schrader, Paul E.; Popolan-Vaida, Denisia M.; Richards-Henderson, Nicole K.; Wilson, Kevin R.; Violi, Angela; Michelsen, Hope A.

2016-01-01

Many oxygenated hydrocarbon species formed during combustion, such as furans, are highly toxic and detrimental to human health and the environment. These species may also increase the hygroscopicity of soot and strongly influence the effects of soot on regional and global climate. However, large furans and associated oxygenated species have not previously been observed in flames, and their formation mechanism and interplay with polycyclic aromatic hydrocarbons (PAHs) are poorly understood. We report on a synergistic computational and experimental effort that elucidates the formation of oxygen-embedded compounds, such as furans and other oxygenated hydrocarbons, during the combustion of hydrocarbon fuels. We used ab initio and probabilistic computational techniques to identify low-barrier reaction mechanisms for the formation of large furans and other oxygenated hydrocarbons. We used vacuum-UV photoionization aerosol mass spectrometry and X-ray photoelectron spectroscopy to confirm these predictions. We show that furans are produced in the high-temperature regions of hydrocarbon flames, where they remarkably survive and become the main functional group of oxygenates that incorporate into incipient soot. In controlled flame studies, we discovered ∼100 oxygenated species previously unaccounted for. We found that large alcohols and enols act as precursors to furans, leading to incorporation of oxygen into the carbon skeletons of PAHs. Our results depart dramatically from the crude chemistry of carbon- and oxygen-containing molecules previously considered in hydrocarbon formation and oxidation models and spearhead the emerging understanding of the oxidation chemistry that is critical, for example, to control emissions of toxic and carcinogenic combustion by-products, which also greatly affect global warming. PMID:27410045

Formation and emission of large furans and oxygenated hydrocarbons from flames.

PubMed

Johansson, K Olof; Dillstrom, Tyler; Monti, Matteo; El Gabaly, Farid; Campbell, Matthew F; Schrader, Paul E; Popolan-Vaida, Denisia M; Richards-Henderson, Nicole K; Wilson, Kevin R; Violi, Angela; Michelsen, Hope A

2016-07-26

Many oxygenated hydrocarbon species formed during combustion, such as furans, are highly toxic and detrimental to human health and the environment. These species may also increase the hygroscopicity of soot and strongly influence the effects of soot on regional and global climate. However, large furans and associated oxygenated species have not previously been observed in flames, and their formation mechanism and interplay with polycyclic aromatic hydrocarbons (PAHs) are poorly understood. We report on a synergistic computational and experimental effort that elucidates the formation of oxygen-embedded compounds, such as furans and other oxygenated hydrocarbons, during the combustion of hydrocarbon fuels. We used ab initio and probabilistic computational techniques to identify low-barrier reaction mechanisms for the formation of large furans and other oxygenated hydrocarbons. We used vacuum-UV photoionization aerosol mass spectrometry and X-ray photoelectron spectroscopy to confirm these predictions. We show that furans are produced in the high-temperature regions of hydrocarbon flames, where they remarkably survive and become the main functional group of oxygenates that incorporate into incipient soot. In controlled flame studies, we discovered ∼100 oxygenated species previously unaccounted for. We found that large alcohols and enols act as precursors to furans, leading to incorporation of oxygen into the carbon skeletons of PAHs. Our results depart dramatically from the crude chemistry of carbon- and oxygen-containing molecules previously considered in hydrocarbon formation and oxidation models and spearhead the emerging understanding of the oxidation chemistry that is critical, for example, to control emissions of toxic and carcinogenic combustion by-products, which also greatly affect global warming.

Formation and emission of large furans and oxygenated hydrocarbons from flames

DOE PAGES

Johansson, K. Olof; Dillstrom, Tyler; Monti, Matteo; ...

2016-07-07

Many oxygenated hydrocarbon species formed during combustion, such as furans, are highly toxic and detrimental to human health and the environment. These species may also increase the hygroscopicity of soot and strongly influence the effects of soot on regional and global climate. However, large furans and associated oxygenated species have not previously been observed in flames, and their formation mechanism and interplay with polycyclic aromatic hydrocarbons (PAHs) are poorly understood. We report on a synergistic computational and experimental effort that elucidates the formation of oxygen-embedded compounds, such as furans and other oxygenated hydrocarbons, during the combustion of hydrocarbon fuels. Wemore » used ab initio and probabilistic computational techniques to identify low-barrier reaction mechanisms for the formation of large furans and other oxygenated hydrocarbons. We used vacuum-UV photoionization aerosol mass spectrometry and X-ray photoelectron spectroscopy to confirm these predictions. We show that fura ns are produced in the high- Temperature regions of hydrocarbon flames, where they remarkably survive and become the main functional group of oxygenates that incorporate into incipient soot. In controlled flame studies, we discovered ~100 oxygenated species previously unaccounted for. We found that large alcohols and enols act as precursors to furans, leading to incorporation of oxygen into the carbon skeletons of PAHs. Our results depart dramatically from the crude chemistry of carbonand oxygen-containing molecules previously considered in hydrocarbon formation and oxidation models and spearhead the emerging understanding of the oxidation chemistry that is critical, for example, to control emissions of toxic and carcinogenic combustion by-products, which also greatly affect global warming.« less

Chlorite dismutases – a heme enzyme family for use in bioremediation and generation of molecular oxygen

PubMed Central

Hofbauer, Stefan; Schaffner, Irene; Furtmüller, Paul G; Obinger, Christian

2014-01-01

Chlorite is a serious environmental concern, as rising concentrations of this harmful anthropogenic compound have been detected in groundwater, drinking water, and soil. Chlorite dismutases (Clds) are therefore important molecules in bioremediation as Clds catalyze the degradation of chlorite to chloride and molecular oxygen. Clds are heme b-containing oxidoreductases present in numerous bacterial and archaeal phyla. This review presents the phylogeny of functional Clds and Cld-like proteins, and demonstrates the close relationship of this novel enzyme family to the recently discovered dye-decolorizing peroxidases. The available X-ray structures, biophysical and enzymatic properties, as well as a proposed reaction mechanism, are presented and critically discussed. Open questions about structure-function relationships are addressed, including the nature of the catalytically relevant redox and reaction intermediates and the mechanism of inactivation of Clds during turnover. Based on analysis of currently available data, chlorite dismutase from “Candidatus Nitrospira defluvii” is suggested as a model Cld for future application in biotechnology and bioremediation. Additionally, Clds can be used in various applications as local generators of molecular oxygen, a reactivity already exploited by microbes that must perform aerobic metabolic pathways in the absence of molecular oxygen. For biotechnologists in the field of chemical engineering and bioremediation, this review provides the biochemical and biophysical background of the Cld enzyme family as well as critically assesses Cld's technological potential. PMID:24519858

Recombination activity of nickel, copper, and oxygen atoms segregating at grain boundaries in mono-like silicon crystals

NASA Astrophysics Data System (ADS)

Ohno, Yutaka; Kutsukake, Kentaro; Deura, Momoko; Yonenaga, Ichiro; Shimizu, Yasuo; Ebisawa, Naoki; Inoue, Koji; Nagai, Yasuyoshi; Yoshida, Hideto; Takeda, Seiji

2016-10-01

Three-dimensional distribution of impurity atoms was determined at functional Σ5{013} and small-angle grain boundaries (GBs) in as-grown mono-like silicon crystals by atom probe tomography combined with transmission electron microscopy, and it was correlated with the recombination activity of those GBs, CGB, revealed by photoluminescence imaging. Nickel (Ni), copper (Cu), and oxygen atoms preferentially segregated at the GBs on which arrays of dislocations existed, while those atoms scarcely segregated at Σ5{013} GBs free from dislocations. Silicides containing Ni and Cu about 5 nm in size and oxides about 1 nm in size were formed along the dislocation arrays on those GBs. The number of segregating impurity atoms per unit GB area for Ni and that for Cu, NNi and NCu, were in a trade-off correlation with that for oxygen, NO, as a function of CGB, while the sum of those numbers was almost constant irrespective of the GB character, CGB, and the dislocation density on GBs. CGB would be explained as a linear combination of those numbers: CGB (in %) ˜400(0.38NO + NNi + NCu) (in atoms/nm2). The GB segregation of oxygen atoms would be better for solar cells, rather than that of metal impurities, from a viewpoint of the conversion efficiency of solar cells.

Polymer membrane based electrolytic cell and process for the direct generation of hydrogen peroxide in liquid streams

NASA Technical Reports Server (NTRS)

White, James H. (Inventor); Schwartz, Michael (Inventor); Sammells, Anthony F. (Inventor)

1997-01-01

An electrolytic cell for generating hydrogen peroxide is provided including a cathode containing a catalyst for the reduction of oxygen, and an anode containing a catalyst for the oxidation of water. A polymer membrane, semipermeable to either protons or hydroxide ions is also included and has a first face interfacing to the cathode and a second face interfacing to the anode so that when a stream of water containing dissolved oxygen or oxygen bubbles is passed over the cathode and a stream of water is passed over the anode, and an electric current is passed between the anode and the cathode, hydrogen peroxide is generated at the cathode and oxygen is generated at the anode.

Mitochondrial Redox Signaling and Tumor Progression.

PubMed

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

2016-03-25

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

Ankyrin-repeat containing proteins of microbes: a conserved structure with functional diversity

PubMed Central

Al-Khodor, Souhaila; Price, Christopher T.; Kalia, Awdhesh; Kwaik, Yousef Abu

2009-01-01

Summary The ankyrin repeat (ANK) is the most common protein-protein interaction motif in nature and predominantly found in eukaryotic proteins. The genome sequencing of various pathogenic or symbiotic bacteria and eukaryotic viruses identified numerous genes encoding ANK-containing proteins that were proposed to have been acquired from eukaryotes by horizontal gene transfer. However, the recent discovery of additional ANK-containing proteins encoded in the genomes of archaea and free-living bacteria suggests either a more ancient origin of the ANK motif or multiple convergent evolution events. Many bacterial pathogens employ various types of secretion systems to deliver ANK-containing proteins into eukaryotic cells where they mimic or manipulate various host functions. Understanding the molecular and biochemical functions of this family of proteins will enhance our understanding of important host-microbe interactions. PMID:19962898

Understanding Oxygen Vacancy Formation, Interaction, Transport, and Strain in SOFC Components via Combined Thermodynamics and First Principles Calculations

NASA Astrophysics Data System (ADS)

Das, Tridip

Understanding of the vacancy formation, interaction, increasing its concentration and diffusion, and controlling its chemical strain will advance the design of mixed ionic and electronic conductor (MIEC) materials via element doping and strain engineering. This is especially central to improve the performance of the solid oxide fuel cell (SOFC), an energy conversion device for sustainable future. The oxygen vacancy concentration grows exponentially with the temperature at dilute vacancy concentration but not at higher concentration, or even decreases due to oxygen vacancy interaction and vacancy ordered phase change. This limits the ionic conductivity. Using density functional theory (DFT), we provided fundamental understanding on how oxygen vacancy interaction originates in one of the typical MIEC, La1-xSrxFeO3-delta (LSF). The vacancy interaction is determined by the interplay of the charge state of multi-valence ion (Fe), aliovalent doping (La/Sr ratio), the crystal structure, and the oxygen vacancy concentration and/or nonstoichiometry (delta). It was found excess electrons left due to the formation of a neutral oxygen vacancy get distributed to Fe directly connected to the vacancy or to the second nearest neighboring Fe, based on crystal field splitting of Fe 3d orbital in different Fe-O polyhedral coordination. The progressively larger polaron size and anisotropic shape changes with increasing Sr-content resulted in increasing oxygen vacancy interactions, as indicated by an increase in the oxygen vacancy formation energy above a critical delta threshold. This was consistent with experimental results showing that Sr-rich LSF and highly oxygen deficient compositions are prone to oxygen-vacancy-ordering-induced phase transformations, while Sr-poor and oxygen-rich LSF compositions are not. Since oxygen vacancy induced phase transformations, cause a decrease in the mobile oxygen vacancy site fraction (X), both delta and X were predicted as a function of temperature and oxygen partial pressure, for multiple LSF compositions and phases using a combined thermodynamics and DFT approach. A detailed oxygen vacancy migration barrier calculation gave the oxygen ionic diffusivity and conductivity. Oxygen vacancy also causes chemical strain, which was treated as a scalar in the literature. However, in many materials, it should be a tensor, which is anisotropic. We illustrate this effect on CeO2, in which it explained a puzzling experiment, which shows significant amplification of measured strain on applied bias in non-stoichiometric Gd doped ceria. The presence of highly localized 4f valence orbital in Ce causes charge disproportionation on the formation of neutral oxygen vacancy, producing anisotropic chemical strain in ceria with cubic symmetry. Understanding of delta and X and anisotropic chemical strain in the lattice has led to the design of better MIEC via element doping and strain engineering of the lattice.

Intracellular singlet oxygen photosensitizers: on the road to solving the problems of sensitizer degradation, bleaching and relocalization.

PubMed

da Silva, Elsa F F; Pimenta, Frederico M; Pedersen, Brian W; Blaikie, Frances H; Bosio, Gabriela N; Breitenbach, Thomas; Westberg, Michael; Bregnhøj, Mikkel; Etzerodt, Michael; Arnaut, Luis G; Ogilby, Peter R

2016-02-01

Selected singlet oxygen photosensitizers have been examined from the perspective of obtaining a molecule that is sufficiently stable under conditions currently employed to study singlet oxygen behavior in single mammalian cells. Reasonable predictions about intracellular sensitizer stability can be made based on solution phase experiments that approximate the intracellular environment (e.g., solutions containing proteins). Nevertheless, attempts to construct a stable sensitizer based solely on the expected reactivity of a given functional group with singlet oxygen are generally not sufficient for experiments in cells; it is difficult to construct a suitable chromophore that is impervious to all of the secondary and/or competing degradative processes that are present in the intracellular environment. On the other hand, prospects are reasonably positive when one considers the use of a sensitizer encapsulated in a specific protein; the local environment of the chromophore is controlled, degradation as a consequence of bimolecular reactions can be mitigated, and genetic engineering can be used to localize the encapsulated sensitizer in a given cellular domain. Also, the option of directly exciting oxygen in sensitizer-free experiments provides a useful complementary tool. These latter systems bode well with respect to obtaining more accurate control of the "dose" of singlet oxygen used to perturb a cell; a parameter that currently limits mechanistic studies of singlet-oxygen-mediated cell signaling.

Interaction of plasmalogens and their diacyl analogs with singlet oxygen in selected model systems

PubMed Central

Broniec, Agnieszka; Klosinski, Radoslaw; Pawlak, Anna; Wrona-Krol, Marta; Thompson, David; Sarna, Tadeusz

2011-01-01

Plasmalogens (Plg) are phospholipids containing vinyl ether linkage at the sn-1 position of the glycerophospholipid backbone. In spite of being quite abundant in humans, the biological role of plasmalogens remains speculative. It has been postulated that plasmalogens are physiological antioxidants with the vinyl ether functionality serving as sacrificial trap for free radicals and singlet oxygen. However, no quantitative data on the efficiency of plasmalogens to scavenge these reactive species are available. In this study, rate constants of quenching of singlet oxygen, generated by photosensitized energy transfer, by several plasmalogens and, for comparison, by their diacyl analogs, were determined by time-resolved detection of phosphorescence at 1270 nm. Relative rates of the interaction of singlet oxygen, with plasmalogens and other lipids in solution and liposomal membranes were measured by electron paramagnetic resonance oximetry and product analysis, employing HPLC-EC detection of cholesterol hydroperoxides and iodometric assay of lipid hydroperoxides. Results show that singlet oxygen interacts with plasmalogens significantly faster than with the other lipids, with he corresponding rate constants being by one-two orders of magnitude greater. The quenching of singlet oxygen by plasmalogens is mostly reactive in nature and results from its preferential interaction with the vinyl ether bond. The data suggest that plasmalogens could protect unsaturated membrane lipids against oxidation induced by singlet oxygen, providing that the oxidation products are not excessively cytotoxic. PMID:21236336

Characterization of 2-Oxindole Forming Heme Enzyme MarE, Expanding the Functional Diversity of the Tryptophan Dioxygenase Superfamily.

PubMed

Zhang, Yuyang; Zou, Yi; Brock, Nelson L; Huang, Tingting; Lan, Yingxia; Wang, Xiaozheng; Deng, Zixin; Tang, Yi; Lin, Shuangjun

2017-08-30

3-Substituted 2-oxindoles are important structural motifs found in many biologically active natural products and pharmaceutical lead compounds. Here, we report an enzymatic formation of the 3-substituted 2-oxindoles catalyzed by MarE in the maremycin biosynthetic pathway in Streptomyces sp. B9173. MarE is a homologue of Fe II /heme-dependent tryptophan 2,3-dioxygenases (TDOs). Typical TDOs usually catalyze the insertion of two oxygen atoms from O 2 into an indole ring to generate N-formylkynurenine (NFK)-like products. In contrast, MarE catalyzes the insertion of a single oxygen atom from O 2 into an indole ring, to probably generate an epoxyindole intermediate that undergoes an unprecedented 2,3-hydride migration to form 2-oxindole structure. MarE shows substrate robustness to catalyze the conversion of a series of 3-substituted indoles into their corresponding 3-substituted 2-oxindoles. Although containing most key amino acid residues conserved in well-known TDO homologues, MarE falls into a separate new subgroup in the phylogenetic tree. The characterization of MarE and its homologue enriches the functional diversities of TDO superfamily and provides a new strategy for discovering novel natural products containing 3-substituted 2-oxindole pharmacophores by genome mining.

Ecological Functions of Off-Channel Habitats of the Willamette River, Oregon, Database and Documentation (1997-2001)

EPA Science Inventory

The database from the Ecological Functions of Off-Channel Habitats of the Willamette River, Oregon project (OCH Project) contains data collected from 1997 through 2001 from multiple research areas of the project, and project documents such as the OCH Research Plan, Quality Assura...

Modern Foreign Languages: A Refereed Journal of Linguistics and Applied Linguistics, 2002.

ERIC Educational Resources Information Center

Ying, Du, Ed; Zidong, Huang, Ed.

2002-01-01

These four issues contain the following articles, written in Chinese (with one exception): "Economy Principles and Chinese Verbless Sentences" (Sze-Wing Tang); "Multiple Wh-Question and the Functional Interpretation of Wh-Phrases" (Wu Ya-Quing); "Towards the Meaning-Text Model and its Function of Lexical Definition"…

Electronic structure of stoichiometric and reduced ZnO from periodic relativistic all electron hybrid density functional calculations using numeric atom-centered orbitals.

PubMed

Viñes, Francesc; Illas, Francesc

2017-03-30

The atomic and electronic structure of stoichiometric and reduced ZnO wurtzite has been studied using a periodic relativistic all electron hybrid density functional (PBE0) approach and numeric atom-centered orbital basis set with quality equivalent to aug-cc-pVDZ. To assess the importance of relativistic effects, calculations were carried out without and with explicit inclusion of relativistic effects through the zero order regular approximation. The calculated band gap is ∼0.2 eV smaller than experiment, close to previous PBE0 results including relativistic calculation through the pseudopotential and ∼0.25 eV smaller than equivalent nonrelativistic all electron PBE0 calculations indicating possible sources of error in nonrelativistic all electron density functional calculations for systems containing elements with relatively high atomic number. The oxygen vacancy formation energy converges rather fast with the supercell size, the predicted value agrees with previously hybrid density functional calculations and analysis of the electronic structure evidences the presence of localized electrons at the vacancy site with a concomitant well localized peak in the density of states ∼0.5 eV above the top of the valence band and a significant relaxation of the Zn atoms near to the oxygen vacancy. Finally, present work shows that accurate results can be obtained in systems involving large supercells containing up to ∼450 atoms using a numeric atomic-centered orbital basis set within a full all electron description including scalar relativistic effects at an affordable cost. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Preparation of stimulus responsive multiple emulsions by membrane emulsification using con a as biochemical sensor.

PubMed

Piacentini, Emma; Drioli, Enrico; Giorno, Lidietta

2011-04-01

In this work, a novel strategy for the controlled fabrication of biomolecular stimulus responsive water-in-oil-in-water (W/O/W) multiple emulsion using the membrane emulsification process was investigated. The emulsions interface was functionalized with a biomolecule able to function as a receptor for a target compound. The interaction between the biomolecular receptor and target stimulus activated the release of bioactive molecules contained within the structured emulsion. A glucose sensitive emulsion was investigated as a model study case. Concanavalin A (Con A) was used as the biomolecular glucose sensor. Various physicochemical strategies for stimulus responsive materials formulation are available in literature, but the preparation of biomolecule-responsive emulsions has been explored for the first time in this paper. The development of novel drug delivery systems requires advanced and highly precise techniques to obtain their particular properties and targeting requirements. The present study has proven the flexibility and suitability of membrane emulsification for the preparation of stable and functional multiple emulsions containing Con A as interfacial biomolecular receptor able to activate the release of a bioactive molecule as a consequence of interaction with the glucose target molecule. The influence of emulsion interfacial composition and membrane emulsification operating conditions on droplets stability and functional properties have been investigated. The release of the bioactive molecule as a function of glucose stimulus and its concentration has been demonstrated. Copyright © 2010 Wiley Periodicals, Inc.

Inhibition of plasma lipid oxidation induced by peroxyl radicals, peroxynitrite, hypochlorite, 15-lipoxygenase, and singlet oxygen by clinical drugs.

PubMed

Morita, Mayuko; Naito, Yuji; Yoshikawa, Toshikazu; Niki, Etsuo

2016-11-15

With increasing evidence showing the involvement of oxidative stress in the pathogenesis of various diseases, the effects of clinical drugs possessing antioxidant functions have received much attention. The unregulated oxidative modification of biological molecules leading to diseases is mediated by multiple oxidants including free radicals, peroxynitrite, hypochlorite, lipoxygenase, and singlet oxygen. The capacity of antioxidants to scavenge or quench oxidants depends on the nature of oxidants. In the present study, the antioxidant effects of several clinical drugs against plasma lipid oxidation induced by the aforementioned five kinds of oxidants were investigated from the production of lipid hydroperoxides, which have been implicated in the pathogenesis of various diseases. Troglitazone acted as a potent peroxyl radical scavenger, whereas probucol and edaravone showed only moderate reactivity and carvedilol, pentoxifylline, and ebselen did not act as radical scavenger. Probucol and edaravone suppressed plasma oxidation mediated by peroxynitrite and hypochlorite. Troglitazone and edaravone inhibited 15-lipoxygenase mediated plasma lipid oxidation, the IC 50 being 20 and 34μM respectively. None of the drugs used in this study suppressed plasma lipid oxidation by singlet oxygen. This study shows that the antioxidant effects of drugs depend on the nature of oxidants and that antioxidants against multiple oxidants are required to cope with oxidative stress in vivo. Copyright © 2016 Elsevier Ltd. All rights reserved.

Quantitative oxygen extraction fraction from 7-Tesla MRI phase: reproducibility and application in multiple sclerosis.

PubMed

Fan, Audrey P; Govindarajan, Sindhuja T; Kinkel, R Philip; Madigan, Nancy K; Nielsen, A Scott; Benner, Thomas; Tinelli, Emanuele; Rosen, Bruce R; Adalsteinsson, Elfar; Mainero, Caterina

2015-01-01

Quantitative oxygen extraction fraction (OEF) in cortical veins was studied in patients with multiple sclerosis (MS) and healthy subjects via magnetic resonance imaging (MRI) phase images at 7 Tesla (7 T). Flow-compensated, three-dimensional gradient-echo scans were acquired for absolute OEF quantification in 23 patients with MS and 14 age-matched controls. In patients, we collected T2*-weighted images for characterization of white matter, deep gray matter, and cortical lesions, and also assessed cognitive function. Variability of OEF across readers and scan sessions was evaluated in a subset of volunteers. OEF was averaged from 2 to 3 pial veins in the sensorimotor, parietal, and prefrontal cortical regions for each subject (total of ~10 vessels). We observed good reproducibility of mean OEF, with intraobserver coefficient of variation (COV)=2.1%, interobserver COV=5.2%, and scan-rescan COV=5.9%. Patients exhibited a 3.4% reduction in cortical OEF relative to controls (P=0.0025), which was not different across brain regions. Although oxygenation did not relate with measures of structural tissue damage, mean OEF correlated with a global measure of information processing speed. These findings suggest that cortical OEF from 7-T MRI phase is a reproducible metabolic biomarker that may be sensitive to different pathologic processes than structural MRI in patients with MS.

Lipoic acid metabolism and mitochondrial redox regulation.

PubMed

Solmonson, Ashley D; DeBerardinis, Ralph J

2017-11-30

Lipoic acid is an essential cofactor for mitochondrial metabolism and is synthesized de novo using intermediates from mitochondrial fatty acid synthesis type II, S-adenosylmethionine and iron-sulfur clusters. This cofactor is required for catalysis by multiple mitochondrial 2-ketoacid dehydrogenase complexes, including pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase, and branched-chain ketoacid dehydrogenase. Lipoic acid also plays a critical role in stabilizing and regulating these multi-enzyme complexes.  Many of these dehydrogenases are regulated by reactive oxygen species, mediated through the disulfide bond of the prosthetic lipoyl moiety.  Collectively, its functions explain why lipoic acid is required for cell growth, mitochondrial activity and coordination of fuel metabolism. Lipoic acid is an essential cofactor for mitochondrial metabolism and is synthesized de novo using intermediates from mitochondrial fatty acid synthesis type II, S-adenosylmethionine and iron-sulfur clusters. This cofactor is required for catalysis by multiple mitochondrial 2-ketoacid dehydrogenase complexes, including pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase, and branched-chain ketoacid dehydrogenase. Lipoic acid also plays a critical role in stabilizing and regulating these multi-enzyme complexes.  Many of these dehydrogenases are regulated by reactive oxygen species, mediated through the disulfide bond of the prosthetic lipoyl moiety.  Collectively, its functions explain why lipoic acid is required for cell growth, mitochondrial activity and coordination of fuel metabolism. Copyright © 2017, The American Society for Biochemistry and Molecular Biology.

A Case of Pulmonary Hypertension Due to Fistulas Between Multiple Systemic Arteries and the Right Pulmonary Artery in an Adult Discovered for Occulted Dyspnoea.

PubMed

Li, Ji-Feng; Zhai, Zhen-Guo; Kuang, Tu-Guang; Liu, Min; Ma, Zhan-Hong; Li, Yi-Dan; Yang, Yuan-Hua

2017-08-01

Pulmonary hypertension (PH) can be caused by a fistula between the systemic and pulmonary arteries. Here, we report a case of PH due to multiple fistulas between systemic arteries and the right pulmonary artery where the ventilation/perfusion scan showed no perfusion in the right lung. A 32-year-old male patient was hospitalised for community-acquired pneumonia. After treatment with antibiotics, the pneumonia was alleviated but dyspnoea persisted. Pulmonary hypertension was diagnosed using right heart catheterisation, which detected the mean pulmonary artery pressure as 37mmHg. The anomalies were confirmed by contrast-enhanced CT scan (CT pulmonary angiography), systemic arterial angiography and pulmonary angiography. Following embolisation of the largest fistula, the haemodynamics and oxygen dynamics did not improve, and even worsened to some extent. After supportive therapy including diuretics and oxygen, the patient's dyspnoea, WHO function class and right heart function by transthoracic echocardiography all improved during follow-up. Pulmonary hypertension can be present even when the right lung perfusion is lost. Closure of fistulas by embolisation, when those fistulas act as the proliferating vessels, may be harmful. Copyright © 2017 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

Safety Standard for Oxygen and Oxygen Systems: Guidelines for Oxygen System Design, Materials Selection, Operations, Storage, and Transportation

NASA Technical Reports Server (NTRS)

1996-01-01

NASA's standard for oxygen system design, materials selection, operation, and transportation is presented. Minimum guidelines applicable to NASA Headquarters and all NASA Field Installations are contained.

Covalency in Metal-Oxygen Multiple Bonds Evaluated Using Oxygen K-edge Spectroscopy and Electronic Structure Theory

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

Minasian, Stefan G.; Keith, Jason M.; Batista, Enrique R.

Advancing theories of how metal oxygen bonding influences metal oxo properties can expose new avenues for innovation in materials science, catalysis, and biochemistry. Historically, spectroscopic analyses of the transition metal peroxyanions, MO4x-, have formed the basis for new M O bonding theories. Herein, relative changes in M O orbital mixing in MO42- (M = Cr, Mo, W) and MO41- (M = Mn, Tc, Re) are evaluated for the first time by non-resonant inelastic X-ray scattering, X-ray absorption spectroscopy using fluorescence and transmission (via a scanning transmission X-ray microscope), and linear-response density functional theory. The results suggest that moving from Groupmore » 6 to Group 7 or down the triads increases M O e () mixing. Meanwhile, t2 mixing ( + ) remains relatively constant within the same Group. These unexpected changes in frontier orbital energy and composition are evaluated in terms of periodic trends in d orbital energy and radial extension.« less

Normal carboxyhaemoglobin level in carbon monoxide poisoning treated with hyperbaric oxygen therapy.

PubMed

Helgeson, Scott A; Wilson, Michael E; Guru, Pramod K

2017-07-24

Throughout the world both intentional and inadvertent exposure to carbon monoxide (CO) remains an important public health issue. While CO poisoning can be lethal, the morbidity is predominantly due to nervous system injury. A previously healthy 22-year-old woman was found unconscious at home by her sister. Her parents were found dead in the house with a recent history of a dysfunctional furnace. She was presumed to have CO poisoning despite an initial carboxyhaemoglobin level of 2.5%. Patient had both clinical and radiological evidence of neurological damage. However, with multiple sessions of hyperbaric oxygen (HBO) therapy she recovered to a near normal functional status. There is no consensus that exists among treating physicians about the role of hyperbaric oxygen in management of neurological injury. The case described here has significant neurological damage related to CO exposure but improved after HBO therapy. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Transverse water relaxation in whole blood and erythrocytes at 3T, 7T, 9.4T, 11.7T and 16.4T; determination of intracellular hemoglobin and extracellular albumin relaxivities.

PubMed

Grgac, Ksenija; Li, Wenbo; Huang, Alan; Qin, Qin; van Zijl, Peter C M

2017-05-01

Blood is a physiological substance with multiple water compartments, which contain water-binding proteins such as hemoglobin in erythrocytes and albumin in plasma. Knowing the water transverse (R 2 ) relaxation rates from these different blood compartments is a prerequisite for quantifying the blood oxygenation level-dependent (BOLD) effect. Here, we report the Carr-Purcell-Meiboom-Gill (CPMG) based transverse (R 2CPMG ) relaxation rates of water in bovine blood samples circulated in a perfusion system at physiological temperature in order to mimic blood perfusion in humans. R 2CPMG values of blood plasma, lysed packed erythrocytes, lysed plasma/erythrocyte mixtures, and whole blood at 3 T, 7 T, 9.4 T, 11.7 T and 16.4 T were measured as a function of hematocrit or hemoglobin concentration, oxygenation, and CPMG inter-echo spacing (τ cp ). R 2CPMG in lysed cells showed a small τ cp dependence, attributed to the water exchange rate between free and hemoglobin-bound water to be much faster than τ cp . This was contrary to the tangential dependence in whole blood, where a much slower exchange between cells and blood plasma applies. Whole blood data were fitted as a function of τ cp using a general tangential correlation time model applicable for exchange as well as diffusion contributions to R 2CPMG , and the intercept R 20blood at infinitely short τ cp was determined. The R 20blood values at different hematocrit and the R 2CPMG values of lysed erythrocyte/plasma mixtures at different hemoglobin concentration were used to determine the relaxivity of hemoglobin inside the erythrocyte (r 2Hb ) and albumin (r 2Alb ) in plasma. The r 2Hb values obtained from lysed erythrocytes and whole blood were comparable at full oxygenation. However, while r 2Hb determined from lysed cells showed a linear dependence on oxygenation, this dependence became quadratic in whole blood. This possibly suggests an additional relaxation effect inside intact cells, perhaps due to hemoglobin proximity to the erythrocyte membrane. However, we cannot exclude that this is a consequence of the simple tangential model used to remove relaxation contributions from exchange and diffusion. The extensive data set presented should be useful for future theory development for the transverse relaxation of blood. Copyright © 2016 Elsevier Inc. All rights reserved.

Solid state oxygen anion and electron mediating membrane and catalytic membrane reactors containing them

DOEpatents

Schwartz, Michael; White, James H.; Sammells, Anthony F.

2005-09-27

This invention relates to gas-impermeable, solid state materials fabricated into membranes for use in catalytic membrane reactors. This invention particularly relates to solid state oxygen anion- and electron-mediating membranes for use in catalytic membrane reactors for promoting partial or full oxidation of different chemical species, for decomposition of oxygen-containing species, and for separation of oxygen from other gases. Solid state materials for use in the membranes of this invention include mixed metal oxide compounds having the brownmillerite crystal structure.

Solid state oxygen anion and electron mediating membrane and catalytic membrane reactors containing them

DOEpatents

Schwartz, Michael; White, James H.; Sammels, Anthony F.

2000-01-01

This invention relates to gas-impermeable, solid state materials fabricated into membranes for use in catalytic membrane reactors. This invention particularly relates to solid state oxygen anion- and electron-mediating membranes for use in catalytic membrane reactors for promoting partial or full oxidation of different chemical species, for decomposition of oxygen-containing species, and for separation of oxygen from other gases. Solid state materials for use in the membranes of this invention include mixed metal oxide compounds having the brownmillerite crystal structure.

Carbon, oxygen and intrinsic defect interactions in germanium-doped silicon

NASA Astrophysics Data System (ADS)

Londos, C. A.; Sgourou, E. N.; Chroneos, A.; Emtsev, V. V.

2011-10-01

Production and annealing of oxygen-vacancy (VO) and oxygen-carbon (CiOi, CiOiI) defects in germanium-doped Czochralski-grown silicon (Cz-Si) containing carbon are investigated. All the samples were irradiated with 2 MeV fast electrons. Radiation-produced defects are studied using infrared spectroscopy by monitoring the relevant bands in optical spectra. For the VO defects, it is established that the doping with Ge affects the thermal stability of VO (830 cm-1) defects as well as their fraction converted to VO2 (888 cm-1) defects. In Ge-free samples containing carbon, it was found that carbon impurity atoms do not affect the thermal stability of VO defects, although they affect the fraction of VO defects that is converted to VO2 complexes. Considering the oxygen-carbon complexes, it is established that the annealing of the 862 cm-1 band associated with the CiOi defects is accompanied with the emergence of the 1048 cm-1 band, which has earlier been assigned to the CsO2i center. The evolution of the CiOiI bands is also traced. Ge doping does not seem to affect the thermal stability of the CiOi and CiOiI defects. Density functional theory (DFT) calculations provide insights into the stability of the defect clusters (VO, CiOi, CiOiI) at an atomic level. Both experimental and theoretical results are consistent with the viewpoint that Ge affects the stability of the VO but does not influence the stability of the oxygen-carbon clusters. DFT calculations demonstrate that C attracts both Oi and VO pairs predominately forming next nearest neighbor clusters in contrast to Ge where the interactions with Oi and VO are more energetically favorable at nearest neighbor configurations.

Hampering Effect of Cholesterol on the Permeation of Reactive Oxygen Species through Phospholipids Bilayer: Possible Explanation for Plasma Cancer Selectivity

NASA Astrophysics Data System (ADS)

van der Paal, Jonas; Verheyen, Claudia; Neyts, Erik C.; Bogaerts, Annemie

2017-01-01

In recent years, the ability of cold atmospheric pressure plasmas (CAPS) to selectively induce cell death in cancer cells has been widely established. This selectivity has been assigned to the reactive oxygen and nitrogen species (RONS) created in CAPs. To provide new insights in the search for an explanation for the observed selectivity, we calculate the transfer free energy of multiple ROS across membranes containing a varying amount of cholesterol. The cholesterol fraction is investigated as a selectivity parameter because membranes of cancer cells are known to contain lower fractions of cholesterol compared to healthy cells. We find that cholesterol has a significant effect on the permeation of reactive species across a membrane. Indeed, depending on the specific reactive species, an increasing cholesterol fraction can lead to (i) an increase of the transfer free energy barrier height and width, (ii) the formation of a local free energy minimum in the center of the membrane and (iii) the creation of extra free energy barriers due to the bulky sterol rings. In the context of plasma oncology, these observations suggest that the increased ingress of RONS in cancer cells can be explained by the decreased cholesterol fraction of their cell membrane.

Sensors, transmitters, and targets in mitochondrial oxygen shortage-a hypoxia-inducible factor relay story.

PubMed

Dehne, Nathalie; Brüne, Bernhard

2014-01-10

Cells sense and respond to a shortage of oxygen by activating the hypoxia-inducible transcription factors HIF-1 and HIF-2 and evoking adaptive responses. Mitochondria are at the center of a hypoxia sensing and responding relay system. Under normoxia, reactive oxygen species (ROS) and nitric oxide (NO) are HIF activators. As their individual flux rates determine their diffusion-controlled interaction, predictions how these radicals affect HIF appear context-dependent. Considering that the oxygen requirement for NO formation limits its role in activating HIF to conditions of ambient oxygen tension. Given the central role of mitochondrial complex IV as a NO target, especially under hypoxia, allows inhibition of mitochondrial respiration by NO to spare oxygen thus, raising the threshold for HIF activation. HIF targets seem to configure a feedback-signaling circuit aimed at gradually adjusting mitochondrial function. In hypoxic cancer cells, mitochondria redirect Krebs cycle intermediates to preserve their biosynthetic ability. Persistent HIF activation lowers the entry of electron-delivering compounds into mitochondria to reduce Krebs cycle fueling and β-oxidation, attenuates the expression of electron transport chain components, limits mitochondria biosynthesis, and provokes their removal by autophagy. Mitochondria can be placed central in a hypoxia sensing-hypoxia responding circuit. We need to determine to which extent and how mitochondria contribute to sense hypoxia, explore whether modulating their oxygen-consuming capacity redirects hypoxic responses in in vivo relevant disease conditions, and elucidate how the multiple HIF targets in mitochondria shape conditions of acute versus chronic hypoxia.

Formation, Fragmentation, and Structures of YxOy(+) (x = 1, 2, y = 1 - 13) Clusters: Collision-Induced Dissociation Experiments and Density Functional Theory Calculations.

PubMed

Glodić, Pavle; Mihesan, Claudia; Klontzas, Emmanouel; Velegrakis, Michalis

2016-02-25

Yttrium oxide cluster cations have been experimentally and theoretically studied. We produced small, oxygen-rich yttrium oxide clusters, YxOy+ (x = 1, 2, y = 1–13), by mixing the laser-produced yttrium plasma with a molecular oxygen jet. Mass spectrometry measurements showed that the most stable clusters are those consisting of one yttrium and an odd number of oxygen atoms of the form YO(+)(2k+1) (k = 0–6). Additionally, we performed collision induced dissociation experiments, which indicated that the loss of pairs of oxygen atoms down to a YO+ core is the preferred fragmentation channel for all clusters investigated. Furthermore, we conduct DFT calculations and we obtained two types of low-energy structures: one containing an yttrium cation core and the other composed of YO+ core and O2 ligands, being in agreement with the observed fragmentation pattern. Finally, from the fragmentation studies, total collision cross sections are obtained and these are compared with geometrical cross sections of the calculated structures.

Identification of the Kelch Family Protein Nd1-L as a Novel Molecular Interactor of KRIT1

PubMed Central

Cutano, Valentina; Martino, Chiara

2012-01-01

Loss-of-function mutations of the KRIT1 gene (CCM1) have been associated with the Cerebral Cavernous Malformation (CCM) disease, which is characterized by serious alterations of brain capillary architecture. The KRIT1 protein contains multiple interaction domains and motifs, suggesting that it might act as a scaffold for the assembly of functional protein complexes involved in signaling networks. In previous work, we defined structure-function relationships underlying KRIT1 intramolecular and intermolecular interactions and nucleocytoplasmic shuttling, and found that KRIT1 plays an important role in molecular mechanisms involved in the maintenance of the intracellular Reactive Oxygen Species (ROS) homeostasis to prevent oxidative cellular damage. Here we report the identification of the Kelch family protein Nd1-L as a novel molecular interactor of KRIT1. This interaction was discovered through yeast two-hybrid screening of a mouse embryo cDNA library, and confirmed by pull-down and co-immunoprecipitation assays of recombinant proteins, as well as by co-immunoprecipitation of endogenous proteins in human endothelial cells. Furthermore, using distinct KRIT1 isoforms and mutants, we defined the role of KRIT1 domains in the Nd1-L/KRIT1 interaction. Finally, functional assays showed that Nd1-L may contribute to the regulation of KRIT1 nucleocytoplasmic shuttling and cooperate with KRIT1 in modulating the expression levels of the antioxidant protein SOD2, opening a novel avenue for future mechanistic studies. The identification of Nd1-L as a novel KRIT1 interacting protein provides a novel piece of the molecular puzzle involving KRIT1 and suggests a potential functional cooperation in cellular responses to oxidative stress, thus expanding the framework of molecular complexes and mechanisms that may underlie the pathogenesis of CCM disease. PMID:22970292

A method for the selection of a functional form for a thermodynamic equation of state using weighted linear least squares stepwise regression

NASA Technical Reports Server (NTRS)

Jacobsen, R. T.; Stewart, R. B.; Crain, R. W., Jr.; Rose, G. L.; Myers, A. F.

1976-01-01

A method was developed for establishing a rational choice of the terms to be included in an equation of state with a large number of adjustable coefficients. The methods presented were developed for use in the determination of an equation of state for oxygen and nitrogen. However, a general application of the methods is possible in studies involving the determination of an optimum polynomial equation for fitting a large number of data points. The data considered in the least squares problem are experimental thermodynamic pressure-density-temperature data. Attention is given to a description of stepwise multiple regression and the use of stepwise regression in the determination of an equation of state for oxygen and nitrogen.

Carotenoids from Marine Organisms: Biological Functions and Industrial Applications

PubMed Central

Galasso, Christian; Corinaldesi, Cinzia; Sansone, Clementina

2017-01-01

As is the case for terrestrial organisms, carotenoids represent the most common group of pigments in marine environments. They are generally biosynthesized by all autotrophic marine organisms, such as bacteria and archaea, algae and fungi. Some heterotrophic organisms also contain carotenoids probably accumulated from food or partly modified through metabolic reactions. These natural pigments are divided into two chemical classes: carotenes (such as lycopene and α- and β-carotene) that are composed of hydrogen and carbon; xanthophylls (such as astaxanthin, fucoxanthin and lutein), which are constituted by hydrogen, carbon and oxygen. Carotenoids, as antioxidant compounds, assume a key role in the protection of cells. In fact, quenching of singlet oxygen, light capture and photosynthesis protection are the most relevant biological functions of carotenoids. The present review aims at describing (i) the biological functions of carotenoids and their benefits for human health, (ii) the most common carotenoids from marine organisms and (iii) carotenoids having large success in pharmaceutical, nutraceutical and cosmeceutical industries, highlighting the scientific progress in marine species cultivation for natural pigments production. PMID:29168774

Influence of atmospheric plasma on physicochemical properties of vapor-grown graphite nanofibers.

PubMed

Seo, Min-Kang; Park, Soo-Jin; Lee, Sang-Kwan

2005-05-01

Vapor-grown graphite nanofibers (GNFs) were modified by plasma treatments using low-pressure plasmas with different gases (Ar gas only and/or Ar/O2 gases), flow rates, pressures, and powers. Surface characterizations and morphologies of the GNFs after plasma treatment were investigated by X-ray photoelectron spectroscopy (XPS), contact angle, titration, and transmission electron microscopy (TEM) measurements. Also, the investigation of thermomechanical behavior and impact strengths of the GNFs/epoxy composites was performed by dynamic-mechanical thermal analysis (DMTA) and Izod impact testing, respectively. The plasma treatment of the fibers changed the surface morphologies by forming a layer with a thickness on the order of 1 nm, mainly consisting of oxygen functional groups such as hydroxyl, carbonyl, and carboxyl groups. After functionalization of the complete surfaces, further plasma treatment did not enhance the superficial oxygen content but slightly changed the portions of the functional groups. Also, the composites with plasma-treated GNFs showed an increase in T(g) and impact strength compared to the composites containing the same amount of plasma-untreated GNFs.

Evolution of Fe/S cluster biogenesis in the anaerobic parasite Blastocystis

PubMed Central

Tsaousis, Anastasios D.; Ollagnier de Choudens, Sandrine; Gentekaki, Eleni; Long, Shaojun; Gaston, Daniel; Stechmann, Alexandra; Vinella, Daniel; Py, Béatrice; Fontecave, Marc; Barras, Frédéric; Lukeš, Julius; Roger, Andrew J.

2012-01-01

Iron/sulfur cluster (ISC)-containing proteins are essential components of cells. In most eukaryotes, Fe/S clusters are synthesized by the mitochondrial ISC machinery, the cytosolic iron/sulfur assembly system, and, in photosynthetic species, a plastid sulfur-mobilization (SUF) system. Here we show that the anaerobic human protozoan parasite Blastocystis, in addition to possessing ISC and iron/sulfur assembly systems, expresses a fused version of the SufC and SufB proteins of prokaryotes that it has acquired by lateral transfer from an archaeon related to the Methanomicrobiales, an important lineage represented in the human gastrointestinal tract microbiome. Although components of the Blastocystis ISC system function within its anaerobic mitochondrion-related organelles and can functionally replace homologues in Trypanosoma brucei, its SufCB protein has similar biochemical properties to its prokaryotic homologues, functions within the parasite’s cytosol, and is up-regulated under oxygen stress. Blastocystis is unique among eukaryotic pathogens in having adapted to its parasitic lifestyle by acquiring a SUF system from nonpathogenic Archaea to synthesize Fe/S clusters under oxygen stress. PMID:22699510

Use of venoarterial extracorporeal membrane oxygenation in fulminant chagasic myocarditis as a bridge to heart transplant

PubMed Central

Durães, André Rodrigues; Figueira, Fernando Augusto Marinho dos Santos; Lafayette, André Rabelo; Martins, Juliana de Castro Solano; Juliano Cavalcante de, Sá

2015-01-01

A 17-year-old Brazilian male presented with progressive dyspnea for 15 days, worsening in the last 24 hours, and was admitted in respiratory failure and cardiogenic shock, with multiple organ dysfunctions. Echocardiography showed a left ventricle ejection fraction of 11%, severe diffuse hypokinesia, and a systolic pulmonary artery pressure of 50mmHg, resulting in the need for hemodynamic support with dobutamine (20mcg/kg/min) and noradrenaline (1.7mcg/kg/min). After 48 hours with no clinical or hemodynamic improvement, an extracorporeal membrane oxygenation was implanted. The patient presented with hemodynamic, systemic perfusion and renal and liver function improvements; however, his cardiac function did not recover after 72 hours, and he was transfer to another hospital. Air transport was conducted from Salvador to Recife in Brazil. A heart transplant was performed with rapid recovery of both liver and kidney functions, as well as good graft function. Histopathology of the explanted heart showed chronic active myocarditis and amastigotes of Trypanosoma cruzi. The estimated global prevalence of T. cruzi infections declined from 18 million in 1991, when the first regional control initiative began, to 5.7 million in 2010. Myocarditis is an inflammatory disease due to infectious or non-infectious conditions. Clinical manifestation is variable, ranging from subclinical presentation to refractory heart failure and cardiogenic shock. Several reports suggest that the use of extracorporeal membrane oxygenation in patients presenting with severe refractory myocarditis is a potential bridging therapy to heart transplant when there is no spontaneous recovery of ventricular function. In a 6-month follow-up outpatient consult, the patient presented well and was asymptomatic. PMID:26761479

An fMRI study on variation of visuospatial cognitive performance of young male due to highly concentrated oxygen administration

NASA Astrophysics Data System (ADS)

Chung, Soon Cheol; Kim, Ik Hyeon; Tack, Gye Rae; Sohn, Jin Hun

2004-04-01

This study investigated the effects of 30% oxygen administration on the visuospatial cognitive performance using fMRI. Eight college students (right-handed, average age 23.5) were selected as subjects for this study. Oxygen supply equipment which gives 21% and 30% oxygen at a constant rate of 8L/min was developed for this study. To measure the performance of visuospatial cognition, two questionnaires with similar difficulty containing 20 questions each were also developed. Experiment was designed as two runs: run for visuospatial cognition test with normal air (21% of oxygen) and run for visuospatial cognition test with highly concentrated air (30% of oxygen). Run consists of 4 blocks and each block has 8 control problems and 5 visuospatial problems. Functional brain images were taken from 3T MRI using single-shot EPI method. Activities of neural network due to performing visuospatial cognition test were identified using subtraction procedure, and activation areas while performing visuospatial cognition test were extracted using double subtraction procedure. Activities were observed at occipital lobe, parietal lobe, and frontal lobe when performing visuospatial cognition test following both 21% and 30% oxygen administration. But in case of only 30% oxygen administration there were more activities at left precuneus, left cuneus, right postcentral gyrus, bilateral middle frontal gyri, right inferior frontal gyrus, left superior frontal gyrus, bilateral uvula, bilateral pyramis, and nodule compared with 21% oxygen administration. From results of visuospatial cognition test, accuracy rate increased in case of 30% oxygen administration. Thus it could be concluded that highly concentrated oxygen administration has positive effects on the visuospatial cognitive performance.

Role of oxygen-containing functional groups in forest fire-generated and pyrolytic chars for immobilization of copper and nickel.

PubMed

Esfandbod, Maryam; Merritt, Christopher R; Rashti, Mehran Rezaei; Singh, Balwant; Boyd, Sue E; Srivastava, Prashant; Brown, Christopher L; Butler, Orpheus M; Kookana, Rai S; Chen, Chengrong

2017-01-01

Char as a carbon-rich material, can be produced under pyrolytic conditions, wildfires or prescribed burn offs for fire management. The objective of this study was to elucidate mechanistic interactions of copper (Cu 2+ ) and nickel (Ni 2+ ) with different chars produced by pyrolysis (green waste, GW; blue-Mallee, BM) and forest fires (fresh-burnt by prescribed fire, FC; aged char produced by wild fire, AC). The pyrolytic chars were more effective sorbents of Cu 2+ (∼11 times) and Ni 2+ (∼5 times) compared with the forest fire chars. Both cross-polarization (CPMAS-NMR) and Bloch decay (BDMAS-NMR) 13 C NMR spectroscopies showed that forest fire chars have higher woody components (aromatic functional groups) and lower polar groups (e.g. O-alkyl C) compared with the pyrolytic chars. The polarity index was greater in the pyrolytic chars (0.99-1.34) than in the fire-generated chars (0.98-1.15), while aromaticity was lower in the former than in the latter. Fourier transform infrared (FTIR) and Raman spectroscopies indicated the binding of carbonate and phosphate with both Cu 2+ and Ni 2+ in all chars, but with a greater extent in pyrolytic than forest fire-generated chars. These findings have demonstrated the key role of char's oxygen-containing functional groups in determining their sorption capacity for the Cu 2+ and Ni 2+ in contaminated lands. Copyright © 2016 Elsevier Ltd. All rights reserved.

Calibrated FMRI.

PubMed

Hoge, Richard D

2012-08-15

Functional magnetic resonance imaging with blood oxygenation level-dependent (BOLD) contrast has had a tremendous influence on human neuroscience in the last twenty years, providing a non-invasive means of mapping human brain function with often exquisite sensitivity and detail. However the BOLD method remains a largely qualitative approach. While the same can be said of anatomic MRI techniques, whose clinical and research impact has not been diminished in the slightest by the lack of a quantitative interpretation of their image intensity, the quantitative expression of BOLD responses as a percent of the baseline T2*- weighted signal has been viewed as necessary since the earliest days of fMRI. Calibrated MRI attempts to dissociate changes in oxygen metabolism from changes in blood flow and volume, the latter three quantities contributing jointly to determine the physiologically ambiguous percent BOLD change. This dissociation is typically performed using a "calibration" procedure in which subjects inhale a gas mixture containing small amounts of carbon dioxide or enriched oxygen to produce changes in blood flow and BOLD signal which can be measured under well-defined hemodynamic conditions. The outcome is a calibration parameter M which can then be substituted into an expression providing the fractional change in oxygen metabolism given changes in blood flow and BOLD signal during a task. The latest generation of calibrated MRI methods goes beyond fractional changes to provide absolute quantification of resting-state oxygen consumption in micromolar units, in addition to absolute measures of evoked metabolic response. This review discusses the history, challenges, and advances in calibrated MRI, from the personal perspective of the author. Copyright © 2012 Elsevier Inc. All rights reserved.

21 CFR 868.5655 - Portable liquid oxygen unit.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Portable liquid oxygen unit. 868.5655 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5655 Portable liquid oxygen unit. (a) Identification. A portable liquid oxygen unit is a portable, thermally insulated container of liquid oxygen that...

21 CFR 868.5655 - Portable liquid oxygen unit.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Portable liquid oxygen unit. 868.5655 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5655 Portable liquid oxygen unit. (a) Identification. A portable liquid oxygen unit is a portable, thermally insulated container of liquid oxygen that...

21 CFR 868.5655 - Portable liquid oxygen unit.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Portable liquid oxygen unit. 868.5655 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5655 Portable liquid oxygen unit. (a) Identification. A portable liquid oxygen unit is a portable, thermally insulated container of liquid oxygen that...

21 CFR 868.5655 - Portable liquid oxygen unit.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Portable liquid oxygen unit. 868.5655 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5655 Portable liquid oxygen unit. (a) Identification. A portable liquid oxygen unit is a portable, thermally insulated container of liquid oxygen that...

21 CFR 868.5655 - Portable liquid oxygen unit.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Portable liquid oxygen unit. 868.5655 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5655 Portable liquid oxygen unit. (a) Identification. A portable liquid oxygen unit is a portable, thermally insulated container of liquid oxygen that...

Novel Semi-Parametric Algorithm for Interference-Immune Tunable Absorption Spectroscopy Gas Sensing

PubMed Central

Michelucci, Umberto; Venturini, Francesca

2017-01-01

One of the most common limits to gas sensor performance is the presence of unwanted interference fringes arising, for example, from multiple reflections between surfaces in the optical path. Additionally, since the amplitude and the frequency of these interferences depend on the distance and alignment of the optical elements, they are affected by temperature changes and mechanical disturbances, giving rise to a drift of the signal. In this work, we present a novel semi-parametric algorithm that allows the extraction of a signal, like the spectroscopic absorption line of a gas molecule, from a background containing arbitrary disturbances, without having to make any assumption on the functional form of these disturbances. The algorithm is applied first to simulated data and then to oxygen absorption measurements in the presence of strong fringes.To the best of the authors’ knowledge, the algorithm enables an unprecedented accuracy particularly if the fringes have a free spectral range and amplitude comparable to those of the signal to be detected. The described method presents the advantage of being based purely on post processing, and to be of extremely straightforward implementation if the functional form of the Fourier transform of the signal is known. Therefore, it has the potential to enable interference-immune absorption spectroscopy. Finally, its relevance goes beyond absorption spectroscopy for gas sensing, since it can be applied to any kind of spectroscopic data. PMID:28991161

A Chaperone Function of NO CATALASE ACTIVITY1 Is Required to Maintain Catalase Activity and for Multiple Stress Responses in Arabidopsis

PubMed Central

Li, Jing; Liu, Juntao; Wang, Guoqiang; Cha, Joon-Yung; Li, Guannan; Chen, She; Li, Zhen; Guo, Jinghua; Zhang, Caiguo; Yang, Yongqing; Kim, Woe-Yeon; Yun, Dae-Jin; Schumaker, Karen S.; Chen, Zhongzhou; Guo, Yan

2015-01-01

Catalases are key regulators of reactive oxygen species homeostasis in plant cells. However, the regulation of catalase activity is not well understood. In this study, we isolated an Arabidopsis thaliana mutant, no catalase activity1-3 (nca1-3) that is hypersensitive to many abiotic stress treatments. The mutated gene was identified by map-based cloning as NCA1, which encodes a protein containing an N-terminal RING-finger domain and a C-terminal tetratricopeptide repeat-like helical domain. NCA1 interacts with and increases catalase activity maximally in a 240-kD complex in planta. In vitro, NCA1 interacts with CATALASE2 (CAT2) in a 1:1 molar ratio, and the NCA1 C terminus is essential for this interaction. CAT2 activity increased 10-fold in the presence of NCA1, and zinc ion binding of the NCA1 N terminus is required for this increase. NCA1 has chaperone protein activity that may maintain the folding of catalase in a functional state. NCA1 is a cytosol-located protein. Expression of NCA1 in the mitochondrion of the nca1-3 mutant does not rescue the abiotic stress phenotypes of the mutant, while expression in the cytosol or peroxisome does. Our results suggest that NCA1 is essential for catalase activity. PMID:25700484

[Telemetry in the clinical setting].

PubMed

Hilbel, Thomas; Helms, Thomas M; Mikus, Gerd; Katus, Hugo A; Zugck, Christian

2008-09-01

Telemetric cardiac monitoring was invented in 1949 by Norman J Holter. Its clinical use started in the early 1960s. In the hospital, biotelemetry allows early mobilization of patients with cardiovascular risk and addresses the need for arrhythmia or oxygen saturation monitoring. Nowadays telemetry either uses vendor-specific UHF band broadcasting or the digital ISM band (Industrial, Scientific, and Medical Band) standardized Wi-Fi network technology. Modern telemetry radio transmitters can measure and send multiple physiological parameters like multi-channel ECG, NIPB and oxygen saturation. The continuous measurement of oxygen saturation is mandatory for the remote monitoring of patients with cardiac pacemakers. Real 12-lead ECG systems with diagnostic quality are an advantage for monitoring patients with chest pain syndromes or in drug testing wards. Modern systems are light-weight and deliver a maximum of carrying comfort due to optimized cable design. Important for the system selection is a sophisticated detection algorithm with a maximum reduction of artifacts. Home-monitoring of implantable cardiac devices with telemetric functionalities are becoming popular because it allows remote diagnosis of proper device functionality and also optimization of the device settings. Continuous real-time monitoring at home for patients with chronic disease may be possible in the future using Digital Video Broadcasting Terrestrial (DVB-T) technology in Europe, but is currently not yet available.

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

PubMed

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

2012-09-30

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

Property Relationship in Organosilanes and Nanotubes Filled Polypropylene Hybrid Composites

PubMed Central

Monsiváis-Barrón, Alejandra J.; Bonilla-Rios, Jaime; Sánchez-Fernández, Antonio

2014-01-01

Polypropylene composites with different filler contents were prepared by creating a masterbatch containing 3 wt%. filler. A variety of silanol groups were used to synthetized three compounds in different media trough a sol-gel process with acetic acid, formic acid and ammonium hydroxide as catalysts. Besides, four different nanotubular fillers were also used to analyze their behavior and compare it with the effect caused by the silanol groups. These tubular structures comprise: unmodified halloysite, carbon nanotubes and functionalized halloysite and carbon nanotubes. Morphological characterization in SEM and STEM/TEM showed dispersion in the polypropylene matrix. According to TGA and DSC measurements thermal behavior remain similar for all the composites. Mechanical test in tension demonstrate that modulus of the composites increases for all samples with a major impact for materials containing silanol groups synthetized in formic acid. Rheological measurements show a significantly increment in viscosity for samples containing unmodified and modified carbon nanotubes. No difference was found for samples containing silanol groups and halloysite when compared to neat polypropylene. Finally, the oxygen transmission rate increased for all samples showing high barrier properties only for samples containing natural and functionalized halloysite nanotubes. PMID:28788233

Property Relationship in Organosilanes and Nanotubes Filled Polypropylene Hybrid Composites.

PubMed

Monsiváis-Barrón, Alejandra J; Bonilla-Rios, Jaime; Sánchez-Fernández, Antonio

2014-10-20

Polypropylene composites with different filler contents were prepared by creating a masterbatch containing 3 wt%. filler. A variety of silanol groups were used to synthetized three compounds in different media trough a sol-gel process with acetic acid, formic acid and ammonium hydroxide as catalysts. Besides, four different nanotubular fillers were also used to analyze their behavior and compare it with the effect caused by the silanol groups. These tubular structures comprise: unmodified halloysite, carbon nanotubes and functionalized halloysite and carbon nanotubes. Morphological characterization in SEM and STEM/TEM showed dispersion in the polypropylene matrix. According to TGA and DSC measurements thermal behavior remain similar for all the composites. Mechanical test in tension demonstrate that modulus of the composites increases for all samples with a major impact for materials containing silanol groups synthetized in formic acid. Rheological measurements show a significantly increment in viscosity for samples containing unmodified and modified carbon nanotubes. No difference was found for samples containing silanol groups and halloysite when compared to neat polypropylene. Finally, the oxygen transmission rate increased for all samples showing high barrier properties only for samples containing natural and functionalized halloysite nanotubes.

Laboratory Measurements of Oxygen Gas Release from Basaltic Minerals Exposed to UV- Radiation: Implications for the Viking Gas Exchange Experiments

NASA Astrophysics Data System (ADS)

Hurowitz, J. A.; Yen, A. S.

2007-12-01

The biology experiments onboard the Viking Landers determined that the Martian soils at Chryse and Utopia Planitia contain an unknown chemical compound of a highly oxidizing nature. The Gas Exchange Experiments (GEx) demonstrated that the humidification of a 1-cc Martian soil sample resulted in the production of as much as 790 nanomoles of oxygen gas. Yen et al. (2000) have provided experimental evidence that superoxide radicals can be generated on plagioclase feldspar (labradorite) grain surfaces by exposure to ultraviolet (UV) light in the presence of oxygen gas. Adsorbed superoxide radicals are thought to react readily with water vapor, and produce oxygen gas in quantities sufficient to explain the Viking GEx results. Direct evidence for the formation of oxygen gas, however, was not provided in the experiments of Yen et al (2000). Accordingly, the motivation of this study is to determine whether superoxide radicals adsorbed on labradorite surfaces are capable of producing oxygen gas upon exposure to water vapor. We have constructed an experimental apparatus that is capable of monitoring oxygen gas release from basaltic mineral powders that have been exposed to UV-radiation under Martian atmospheric pressure conditions. The apparatus consists of a stainless-steel vacuum chamber with a UV- transparent window where sample radiation exposures are performed. The vacuum chamber has multiple valved ports for injection of gases and water vapor. The vacuum chamber is connected via a precision leak valve to a quadrupole mass spectrometer, which measures changes in the composition of the headspace gases over our mineral samples. We will report on the results of our experiments, which are aimed at detecting and quantifying oxygen gas release from UV-exposed basaltic mineral samples using this new experimental facility. These results will further constrain whether superoxide ions adsorbed on mineral surfaces provide a viable explanation for the Viking GEx results, which have been of considerable controversy in the roughly three decades since the measurements were first made.

Apparatus and method for the electrolysis of water

DOEpatents

Greenbaum, Elias

2015-04-21

An apparatus for the electrolytic splitting of water into hydrogen and/or oxygen, the apparatus comprising: (i) at least one lithographically-patternable substrate having a surface; (ii) a plurality of microscaled catalytic electrodes embedded in said surface; (iii) at least one counter electrode in proximity to but not on said surface; (iv) means for collecting evolved hydrogen and/or oxygen gas; (v) electrical powering means for applying a voltage across said plurality of microscaled catalytic electrodes and said at least one counter electrode; and (vi) a container for holding an aqueous electrolyte and housing said plurality of microscaled catalytic electrodes and said at least one counter electrode. Electrolytic processes using the above electrolytic apparatus or functional mimics thereof are also described.

The Carbonates in ALH 84001 Record the Evolution of the Martian Atmosphere Through Multiple Formation Events

NASA Technical Reports Server (NTRS)

Shaheen, R.; Niles, P. B.; Corrgan, C.

2012-01-01

Current Martian conditions restrict the presence of liquid water due to low temperatures (approx 210K), a thin atmosphere (approx 7mb), and intense UV radiation. However, past conditions on Mars may have been different with the possibility that the ancient Martian climate was warm and wet with a dense CO2 atmosphere. The cycling of carbon on Mars through atmospheric CO2 and carbonate minerals is critical for deciphering its climate history. In particular stable isotopes contained in carbonates can provide information of their origin and formation environment as well as possibly hinting at the composition of global reservoirs such as atmospheric CO2. Martian meteorite ALH 84001 contains widely studied carbonate rosettes that have been dated to approx. 3.9 Ga and have been used to interpret climatic conditions present at that time. However, there is mount-ing evidence for multiple episodes of carbonate formation in ALH 84001 with potentially distinct isotopic compositions. This study seeks to tease out these different carbonate assemblages using stepped phosphoric acid dissolution and analysis of carbon and triple oxygen stable isotopes. In addition, we report SIMS analyses of the delta O-18 several petrographically unusual carbonate phases in the meteorite.

Apparatus for Screening Multiple Oxygen-Reduction Catalysts

NASA Technical Reports Server (NTRS)

Whitacre, Jay; Narayanan, Sekharipuram

2009-01-01

An apparatus that includes an array of multiple electrodes has been invented as a means of simultaneously testing multiple materials for their utility as oxygen-reduction catalysts in fuel cells. The apparatus ensures comparability of test results by exposing all the catalyst-material specimens to the same electrolytic test solution at the same potential. Heretofore, it has been possible to test only one specimen at a time, using a precise rotating disk electrode that provides a controlled flux of solution to the surface of the specimen.

Quantifying oxygen in paper-based cell cultures with luminescent thin film sensors.

PubMed

Boyce, Matthew W; Kenney, Rachael M; Truong, Andrew S; Lockett, Matthew R

2016-04-01

Paper-based scaffolds are an attractive material for generating 3D tissue-like cultures because paper is readily available and does not require specialized equipment to pattern, cut, or use. By controlling the exchange of fresh culture medium with the paper-based scaffolds, we can engineer diffusion-dominated environments similar to those found in spheroids or solid tumors. Oxygen tension directly regulates cellular phenotype and invasiveness through hypoxia-inducible transcription factors and also has chemotactic properties. To date, gradients of oxygen generated in the paper-based cultures have relied on cellular response-based readouts. In this work, we prepared a luminescent thin film capable of quantifying oxygen tensions in apposed cell-containing paper-based scaffolds. The oxygen sensors, which are polystyrene films containing a Pd(II) tetrakis(pentafluorophenyl)porphyrin dye, are photostable, stable in culture conditions, and not cytotoxic. They have a linear response for oxygen tensions ranging from 0 to 160 mmHg O2, and a Stern-Volmer constant (K sv) of 0.239 ± 0.003 mmHg O2 (-1). We used these oxygen-sensing films to measure the spatial and temporal changes in oxygen tension for paper-based cultures containing a breast cancer line that was engineered to constitutively express a fluorescent protein. By acquiring images of the oxygen-sensing film and the fluorescently labeled cells, we were able to approximate the oxygen consumption rates of the cells in our cultures.

Potential for drug interactions mediated by polymorphic flavin-containing monooxygenase 3 in human livers.

PubMed

Shimizu, Makiko; Shiraishi, Arisa; Sato, Ayumi; Nagashima, Satomi; Yamazaki, Hiroshi

2015-02-01

Human flavin-containing monooxygenase 3 (FMO3) in the liver catalyzes a variety of oxygenations of nitrogen- and sulfur-containing medicines and xenobiotic substances. Because of growing interest in drug interactions mediated by polymorphic FMO3, benzydamine N-oxygenation by human FMO3 was investigated as a model reaction. Among the 41 compounds tested, trimethylamine, methimazole, itopride, and tozasertib (50 μM) suppressed benzydamine N-oxygenation at a substrate concentration of 50 μM by approximately 50% after co-incubation. Suppression of N-oxygenation of benzydamine, trimethylamine, itopride, and tozasertib and S-oxygenation of methimazole and sulindac sulfide after co-incubation with the other five of these six substrates was compared using FMO3 proteins recombinantly expressed in bacterial membranes. Apparent competitive inhibition by methimazole (0-50 μM) of sulindac sulfide S-oxygenation was observed with FMO3 proteins. Sulindac sulfide S-oxygenation activity of Arg205Cys variant FMO3 protein was likely to be suppressed more by methimazole than wild-type or Val257Met variant FMO3 protein was. These results suggest that genetic polymorphism in the human FMO3 gene may lead to changes of drug interactions for N- or S-oxygenations of xenobiotics and endogenous substances and that a probe battery system of benzydamine N-oxygenation and sulindac sulfide S-oxygenation activities is recommended to clarify the drug interactions mediated by FMO3. Copyright © 2014 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.

Operating room fire prevention: creating an electrosurgical unit fire safety device.

PubMed

Culp, William C; Kimbrough, Bradly A; Luna, Sarah; Maguddayao, Aris J

2014-08-01

To reduce the incidence of surgical fires. Operating room fires represent a potentially life-threatening hazard and are triggered by the electrosurgical unit (ESU) pencil. Carbon dioxide is a fire suppressant and is a routinely used medical gas. We hypothesize that a shroud of protective carbon dioxide covering the tip of the ESU pencil displaces oxygen, thereby preventing fire ignition. Using 3-dimensional modeling techniques, a polymer sleeve was created and attached to an ESU pencil. This sleeve was connected to a carbon dioxide source and directed the gas through multiple precisely angled ports, generating a cone of fire-suppressive carbon dioxide surrounding the active pencil tip. This device was evaluated in a flammability test chamber containing 21%, 50%, and 100% oxygen with sustained ESU activation. The sleeve was tested with and without carbon dioxide (control) until a fuel was ignited or 30 seconds elapsed. Time to ignition was measured by high-speed videography. Fires were ignited with each control trial (15/15 trials). The control group median ± SD ignition time in 21% oxygen was 3.0 ± 2.4 seconds, in 50% oxygen was 0.1 ± 1.8 seconds, and in 100% oxygen was 0.03 ± 0.1 seconds. No fire was observed when the fire safety device was used in all concentrations of oxygen (0/15 trials; P < 0.0001). The exact 95% confidence interval for absolute risk reduction of fire ignition was 76% to 100%. A sleeve creating a cone of protective carbon dioxide gas enshrouding the sparks from an ESU pencil effectively prevents fire in a high-flammability model. Clinical application of this device may reduce the incidence of operating room fires.

Functional MR imaging assessment of a non-responsive brain injured patient.

PubMed

Moritz, C H; Rowley, H A; Haughton, V M; Swartz, K R; Jones, J; Badie, B

2001-10-01

Functional magnetic resonance imaging (fMRI) was requested to assist in the evaluation of a comatose 38-year-old woman who had sustained multiple cerebral contusions from a motor vehicle accident. Previous electrophysiologic studies suggested absence of thalamocortical processing in response to median nerve stimulation. Whole-brain fMRI was performed utilizing visual, somatosensory, and auditory stimulation paradigms. Results demonstrated intact task-correlated sensory and cognitive blood oxygen level dependent (BOLD) hemodynamic response to stimuli. Electrodiagnostic studies were repeated and evoked potentials indicated supratentorial recovery in the cerebrum. At 3-months post trauma the patient had recovered many cognitive & sensorimotor functions, accurately reflecting the prognostic fMRI evaluation. These results indicate that fMRI examinations may provide a useful evaluation for brain function in non-responsive brain trauma patients.

Psychometrics of Multiple Choice Questions with Non-Functioning Distracters: Implications to Medical Education.

PubMed

Deepak, Kishore K; Al-Umran, Khalid Umran; AI-Sheikh, Mona H; Dkoli, B V; Al-Rubaish, Abdullah

2015-01-01

The functionality of distracters in a multiple choice question plays a very important role. We examined the frequency and impact of functioning and non-functioning distracters on psychometric properties of 5-option items in clinical disciplines. We analyzed item statistics of 1115 multiple choice questions from 15 summative assessments of undergraduate medical students and classified the items into five groups by their number of non-functioning distracters. We analyzed the effect of varying degree of non-functionality ranging from 0 to 4, on test reliability, difficulty index, discrimination index and point biserial correlation. The non-functionality of distracters inversely affected the test reliability and quality of items in a predictable manner. The non-functioning distracters made the items easier and lowered the discrimination index significantly. Three non-functional distracters in a 5-option MCQ significantly affected all psychometric properties (p < 0.5). The corrected point biserial correlation revealed that the items with 3 functional options were psychometrically as effective as 5-option items. Our study reveals that a multiple choice question with 3 functional options provides lower most limit of item format that has adequate psychometric property. The test containing items with less number of functioning options have significantly lower reliability. The distracter function analysis and revision of nonfunctioning distracters can serve as important methods to improve the psychometrics and reliability of assessment.

OCAM - A CELSS modeling tool: Description and results. [Object-oriented Controlled Ecological Life Support System Analysis and Modeling

NASA Technical Reports Server (NTRS)

Drysdale, Alan; Thomas, Mark; Fresa, Mark; Wheeler, Ray

1992-01-01

Controlled Ecological Life Support System (CELSS) technology is critical to the Space Exploration Initiative. NASA's Kennedy Space Center has been performing CELSS research for several years, developing data related to CELSS design. We have developed OCAM (Object-oriented CELSS Analysis and Modeling), a CELSS modeling tool, and have used this tool to evaluate CELSS concepts, using this data. In using OCAM, a CELSS is broken down into components, and each component is modeled as a combination of containers, converters, and gates which store, process, and exchange carbon, hydrogen, and oxygen on a daily basis. Multiple crops and plant types can be simulated. Resource recovery options modeled include combustion, leaching, enzyme treatment, aerobic or anaerobic digestion, and mushroom and fish growth. Results include printouts and time-history graphs of total system mass, biomass, carbon dioxide, and oxygen quantities; energy consumption; and manpower requirements. The contributions of mass, energy, and manpower to system cost have been analyzed to compare configurations and determine appropriate research directions.

Theoretical insight into an empirical rule about organic corrosion inhibitors containing nitrogen, oxygen, and sulfur atoms

NASA Astrophysics Data System (ADS)

Guo, Lei; Obot, Ime Bassey; Zheng, Xingwen; Shen, Xun; Qiang, Yujie; Kaya, Savaş; Kaya, Cemal

2017-06-01

Steel is an important material in industry. Adding heterocyclic organic compounds have proved to be very efficient for steel protection. There exists an empirical rule that the general trend in the inhibition efficiencies of molecules containing heteroatoms is such that O < N < S. However, an atomic-level insight into the inhibition mechanism is still lacked. Thus, in this work, density functional theory calculations was used to investigate the adsorption of three typical heterocyclic molecules, i.e., pyrrole, furan, and thiophene, on Fe(110) surface. The approach is illustrated by carrying out geometric optimization of inhibitors on the stable and most exposed plane of α-Fe. Some salient features such as charge density difference, changes of work function, density of states were detailedly described. The present study is helpful to understand the afore-mentioned experiment rule.

Enzymatic defenses against the toxicity of oxygen and of streptonigrin in Escherichia coli.

PubMed

Hassan, H M; Fridovich, I

1977-03-01

Anaerobically grown Escherichia coli K-12 contain only one superoxide dismutase and that is the iron-containing isozyme found in the periplasmic space. Exposure to oxygen caused the induction of a manganese-containing superoxide dismutase and of another, previously undescribed, superoxide dismutase, as well as of catalase and peroxidase. These inductions differed in their responsiveness towards oxygen. Thus the very low levels of oxygen present in deep, static, aerobic cultures were enough for nearly maximal induction of the manganese-superoxide dismutase. In contrast, induction of the new superoxide dismutase, catalase, and peroxidase required the much higher levels of oxygen achieved in vigorously agitated aerobic cultures. Anaerobically grown cells showed a much greater oxygen enhancement of the lethality of streptonigrin than did aerobically grown cells, in accord with the proposal that streptonigrin can serve as an intracellular source of superoxide. Anaerobically grown cells in which enzyme inductions were prevented by puromycin were damaged by exposure to air. This damage was evidenced both as a decline in viable cell count and as structural abnormalities evident under an electron microscope.

Study on the effect of polydimethylsiloxane from the viewpoint of oxygen content in oil.

PubMed

Yawata, Miho; Iwahashi, Maiko; Hori, Ryuji; Shiramasa, Hiroshi; Totani, Nagao

2014-01-01

It has been reported that polydimethylsiloxane (PDMS) inhibits oxygen dissolution into oil by forming a monolayer on the surface of the oil, thereby reducing thermal oxidation. In the present study, the distribution of PDMS was determined by the inductively coupled plasma atomic emission spectroscopy in standing PDMS-containing canola oil. PDMS did not disperse in the oil uniformly, but there was a tendency that the PDMS concentration decreased as the depth of oil increased, and the concentration of the bottom part was the lowest. When canola oil was covered with PDMS by dropping it gently on the surface of the oil and kept at 60°C, the oxygen content and oxidation of the oil were lower than those of the control canola oil. PDMS-containing canola oil and canola oil were heated with stirring from room temperature to 180°C, and then allowed to stand while cooling. Oxygen contents of both oils increased up to 120°C then dropped abruptly. While cooling, oxygen contents sharply increased at 100°C and approached the saturation content, although the increase for PDMS-containing canola oil was a little slow. Likewise, the thermal treatment of PDMS-containing canola oil and canola oil at 180°C for 1 h under stirring was repeated 5 times with standing intervals for 2-3 days at room temperature. Oxidation of the former was less than that of the latter in spite of its high oxygen content. In conclusion, the oxygen content of oil with/without PDMS addition increased, but oxidation of PDMS-containing canola oil was inhibited both during heating and standing with intermittent heating. It was suggested that PDMS exerted its antioxidative effect regardless of whether it covered the oil or was dispersed in it.

Cutaneous Respirometry as Novel Technique to Monitor Mitochondrial Function: A Feasibility Study in Healthy Volunteers

PubMed Central

Stolker, Robert Jan; Mik, Egbert

2016-01-01

Background The protoporphyrin IX-triplet state lifetime technique (PpIX-TSLT) is proposed as a potential clinical non-invasive tool to monitor mitochondrial function. This technique has been evaluated in several animal studies. Mitochondrial respirometry allows measurement in vivo of mitochondrial oxygen tension (mitoPO2) and mitochondrial oxygen consumption (mitoVO2) in skin. This study describes the first use of a clinical prototype in skin of humans. Methods The clinical prototype was tested in 30 healthy volunteers. A self-adhesive patch containing 2 mg 5-aminolevulinic acid (ALA) was applied on the skin of the anterior chest wall (sternal) for induction of mitochondrial protoporphyrin IX and was protected from light for 5 h. MitoPO2 was measured by means of oxygen-dependent delayed fluorescence of protoporphyrin IX. MitoVO2 was determined by dynamic mitoPO2 measurements on the primed skin, while locally blocking oxygen supply by applying local pressure with the measurement probe. MitoPO2 was recorded before and during a 60-s period of compression of the microcirculation, at an interval of 1 Hz. Oxygen consumption (i.e. the local oxygen disappearance rate) was calculated from the decay of the mitoPO2 slope. Results Oxygen-dependent delayed fluorescence measurements were successfully performed in the skin of 27 volunteers. The average value (± SD) of mitoPO2 was 44 ± 17 mmHg and mean mitoVO2 values were 5.8 ± 2.3 and 6.1 ± 1.6 mmHg s-1 at a skin temperature of 34°C and 40°C, respectively. No major discomfort during measurement and no long-term dermatological abnormalities were reported in a survey performed 1 month after measurements. Conclusion These results show that the clinical prototype allows measurement of mitochondrial oxygenation and oxygen consumption in humans. The development of this clinically applicable device offers opportunities for further evaluation of the technique in humans and the start of first clinical studies. PMID:27455073

Synthesis of boron nitride powders

NASA Astrophysics Data System (ADS)

Dreissig, Dirk Horst

2002-09-01

In the materials science community there is much interest in the development of new, efficient approaches for preparing ceramic powders having properties or performance characteristics not found with powders produced by traditional metallurgical synthesis methods. In this regard, aerosol-based syntheses are finding general acceptance for the preparation of non-metal and metal oxide powders. In contrast, much less effort has been given to aerosol-type syntheses for non-oxide powders despite potentially useful benefits. This dissertation describes the application of two chemical systems in aerosol assisted vapor phase synthesis (AAVS) for the preparation of spherical morphology boron oxynitride, BNxOy, powders that are subsequently converted to spherical morphology boron nitride in a second nitridation step. Chapter 1 describes the AAVS synthesis of BNxOy powders using a reaction of an aqueous boric acid containing aerosol with ammonia at 1000°C. The effect of reactor tube material, total gas flow rate, ammonia concentration, boric acid concentration, and urea addition to the boric acid aerosol on the percent oxygen composition is described. The resulting BNxOy powders contain significant amounts of oxygen that require replacement in a second stage nitridation reaction at elevated temperature under ammonia. The influences of the reaction temperature profile, crucible geometry and transformation additive on final oxygen composition and powder crystallinity are described. Chapter 2 outlines the formation of BNxOy powders from an AAVS reaction between the boron precursor (MeO)3B and ammonia. The formation of the powders is studied as a function of total gas flow rate and ammonia concentration. In all cases the resulting powders contain lower levels of oxygen compared to powders produced from aqueous boric acid aerosols. The conversion of the BNxOy powders in the second stage nitridation reaction with ammonia is examined as a function of crucible geometry, temperature profile and ammonia flow rate. In support of this process, the molecular reaction between (MeO)3B and NH3 was reexamined. The adduct, (MeO)3B·NH3, was isolated and its molecular structure determined by single crystal X-ray diffraction techniques. The results of these studies provide guidance for more detailed studies that should result in industrial scale synthesis of spherical morphology BN which currently is not formed by standard metallurgical syntheses. This new material has potential applications in several areas including the formation of BN loaded organic polymer composites.

Oxidative protein modification as predigestive mechanism of the carnivorous plant Dionaea muscipula: an hypothesis based on in vitro experiments.

PubMed

Galek, H; Osswald, W F; Elstner, E F

1990-01-01

Aqueous leaf extracts from Dionaea muscipula contain quinones such as the naphthoquinone plumbagin that couple to different NADH-dependent diaphorases, producing superoxide and hydrogen peroxide upon autoxidation. Upon preincubation of Dionaea extracts with certain diaphorases and NADH in the presence of serumalbumin (SA), subsequent tryptic digestion of SA is facilitated. Since the secretroy glands of Droseracea contain proteases and possibly other degradative enzymes it is suggested that the presence of oxygen-activating redox cofactors in the extracts function as extracellular predigestive oxidants which render membrane-bound proteins of the prey (insects) more susceptible to proteolytic attacks.

Color film preservation system: Breadboard development

NASA Technical Reports Server (NTRS)

1984-01-01

The development of an economically feasible system to prevent and/or substantially reduce the degradation of the color dyes of the retinal reflex images recorded on color slide films is discussed. Three different types of film storage systems were designed, fabricated, and tested. An extruded plastic cylindrical container was pressurized and no observable leakage occurred, indicating that long term storage is possible. An operational breadboard was fabricated. The system offers the capability to determine purging requirements to achieve various levels of oxygen concentration and precise leakage of various container configurations. The system has digitial display of oxygen content of the container, automatic control of the oxygen content as well as of the container to atmosphere pressure differential, and flow rate readout during purging.

Nitrite therapy after cardiac arrest reduces ROS generation, improves cardiac and neurological function and enhances survival via reversible inhibition of mitochondrial complex I

PubMed Central

Dezfulian, Cameron; Shiva, Sruti; Alekseyenko, Aleksey; Pendyal, Akshay; Beiser, DG; Munasinghe, Jeeva P.; Anderson, Stasia A.; Chesley, Christopher F.; Hoek, TL Vanden; Gladwin, Mark T.

2009-01-01

Background Three-fourths of cardiac arrest survivors die prior to hospital discharge or suffer significant neurological injury. Excepting therapeutic hypothermia and revascularization, no novel therapies have been developed that improve survival or cardiac and neurological function after resuscitation. Nitrite (NO2−) increases cellular resilience to focal ischemia-reperfusion injury in multiple organs. We hypothesized that nitrite therapy may improve outcomes after the unique global ischemia-reperfusion insult of cardiopulmonary arrest. Methods and Results We developed a mouse model of cardiac arrest characterized by 12-minutes of normothermic asystole and a high cardiopulmonary resuscitation (CPR) rate. In this model, global ischemia and CPR was associated with blood and organ nitrite depletion, reversible myocardial dysfunction, impaired alveolar gas exchange, neurological injury and an approximate 50% mortality. A single low dose of intravenous nitrite (50 nmol=1.85 μmol/kg=0.13 mg/kg) compared to blinded saline placebo given at CPR initiation with epinephrine improved cardiac function, survival and neurological outcomes. From a mechanistic standpoint, nitrite treatment restored intracardiac nitrite and increased S-nitrosothiol levels, decreased pathological cardiac mitochondrial oxygen consumption due to reactive oxygen species formation and prevented oxidative enzymatic injury via reversible specific inhibition of respiratory chain complex I. Conclusion Nitrite therapy after resuscitation from 12-minutes of asystole rapidly and reversibly modulated mitochondrial reactive oxygen species generation during early reperfusion, limiting acute cardiac dysfunction and death, as well as neurological impairment in survivors. PMID:19704094

Influence of encapsulated heat shock protein HSP70 on the basic functional properties of blood phagocytes.

PubMed

Kochetkova, O Yu; Yurinskaya, M M; Evgen'ev, M B; Zatsepina, O G; Shabarchina, L I; Suslikov, A V; Tikhonenko, S A; Vinokurov, M G

2015-11-01

Microencapsulated heat shock proteins HSP 70 were studied in terms of their effects on neutrophil apoptosis, production of reactive oxygen species, and secretion of TNF-α by human neurtrophils and monocytes. Encapsulated HSP70 inhibited neutrophil apoptosis by 65% as compared to the effect of nonencapsulated HSP70; TNF-α production by the promonocytic THP-1 cells was similarly inhibited by the non-encapsulated and encapsulated HSP70. Thus, the polyelectrolyte micromolecules can be used as containers for effective delivery of HSP70 up to neutrophils and monocytes to correct the innate immunity functions.

Laser-guided direct writing for three-dimensional tissue engineering: Analysis and application of radiation forces

NASA Astrophysics Data System (ADS)

Nahmias, Yaakov Koby

Tissue Engineering aims for the creation of functional tissues or organs using a combination of biomaterials and living cells. Artificial tissues can be implanted in patients to restore tissue function that was lost due to trauma, disease, or genetic disorder. Tissue equivalents may also be used to screen the effects of drugs and toxins, reducing the use of animals in research. One of the principle limitations to the size of engineered tissue is oxygen and nutrient transport. Lacking their own vascular bed, cells embedded in the engineered tissue will consume all available oxygen within hours while out branching blood vessels will take days to vascularize the implanted tissue. Establishing capillaries within the tissue prior to implantation can potentially eliminate this limitation. One approach to establishing capillaries within the tissue is to directly write endothelial cells with micrometer accuracy as it is being built. The patterned endothelial cells will then self-assemble into vascular structures within the engineering tissue. The cell patterning technique known as laser-guided direct writing can confine multiple cells in a laser beam and deposit them as a steady stream on any non-absorbing surface with micrometer scale accuracy. By applying the generalized Lorenz-Mie theory for light scattering on laser-guided direct writing we were able to accurately predict the behavior of with various cells and particles in the focused laser. In addition, two dimensionless parameters were identified for general radiation-force based system design. Using laser-guided direct writing we were able to direct the assembly of endothelial vascular structures with micrometer accuracy in two and three dimensions. The patterned vascular structures provided the backbone for subsequent in vitro liver morphogenesis. Our studies show that hepatocytes migrate toward and adhere to endothelial vascular structures in response to endothelial-secreted hepatocyte growth factor (HGF). Our approach has the advantage of retaining the natural heterotypic cell-cell interaction and spatial arrangement of native tissue, which is important for proper tissue function.* *This dissertation is a compound document (contains both a paper copy and a CD as part of the dissertation). The CD requires the following system requirements: Microsoft Office; Windows MediaPlayer or RealPlayer.

Titanium aluminide intermetallic alloys with improved wear resistance

DOEpatents

Qu, Jun; Lin, Hua-Tay; Blau, Peter J.; Sikka, Vinod K.

2014-07-08

The invention is directed to a method for producing a titanium aluminide intermetallic alloy composition having an improved wear resistance, the method comprising heating a titanium aluminide intermetallic alloy material in an oxygen-containing environment at a temperature and for a time sufficient to produce a top oxide layer and underlying oxygen-diffused layer, followed by removal of the top oxide layer such that the oxygen-diffused layer is exposed. The invention is also directed to the resulting oxygen-diffused titanium aluminide intermetallic alloy, as well as mechanical components or devices containing the improved alloy composition.

Method for obtaining oxygen from lunar or similar soil

NASA Technical Reports Server (NTRS)

Downs, W. R. (Inventor)

1973-01-01

Recovery of oxygen from soil containing metal oxides such as alumina, silica, calcia, magnesia, and ilmenite wherein the material containing the oxides is placed in a vessel and reacted with fluorine to provide oxygen and metal fluorides. The oxygen produced from the reaction is recovered and stored, after further purifying processes, and the metal fluorides are further reacted with potassium vapor to provide potassium fluoride and free metals. The potassium fluoride is than subjected to electrolysis whereby the potassium and fluorine are separated and are recycled for further use in the system. Valuable free metals are recovered for other uses.

Solid-phase fullerene-like nanostructures as singlet oxygen photosensitizers in liquid media

NASA Astrophysics Data System (ADS)

Belousova, I. M.; Danilov, O. B.; Kiselev, V. M.; Kislyakov, I. M.; Kris'ko, T. K.; Murav'eva, T. D.; Videnichev, D. A.

2007-04-01

Singlet oxygen generation by fullerene and astralen containing surfaces and powders under visible irradiation was studied in water and organic liquids by means of 1Δ g state luminescence and chemical scavenger transmittance measurements. The chemical method, pioneered for solid photosensitizers of 10 II, allowed to measure the singlet oxygen concentration in the aqueous medium down to 10 8 cm -3. The singlet oxygen sensitizing by the solid-phase fullerene-containing systems was found to be 100 times less effective then by fullerene in solution. The results obtained confirm the applicability of these structures in biology and medicine.

Mathematical modeling of the biodegradation of residual hydrocarbon in a variably-saturated sand column.

PubMed

Geng, Xiaolong; Boufadel, Michel C; Wrenn, Brian

2013-04-01

The biodegradation of heptadecane in five sand columns was modeled using a multiplicative Monod approach. Each column contained 1.0 kg of sand and 2 g of heptadecane, and was supplied with an artificial seawater solution containing nutrients at a flow rate that resulted in unsaturated flow through the column. All nutrients were provided in excess with the exception of nitrate whose influent concentration was 0.1, 0.5, 1.0, 2.5, or 5.0 mg N/L. The experiment was run around 912 h until no measurable oxygen consumption or CO2 production was observed. The residual mass of heptadecane was measured at the end of the experiments and the biodegradation was monitored based on oxygen consumption and CO2 production. Biodegradation kinetic parameters were estimated by fitting the model to experimental data of oxygen, CO2, and residual mass of heptadecane obtained from the two columns having influent nitrate-N concentration of 0.5 and 2.5 mg/L. Noting that the oxygen and CO2 measurements leveled off at around 450 h, we fitted the model to these data for that range. The estimated parameters fell in within the range reported in the literature. In particular, the half-saturation constant for nitrate utilization, [Formula: see text], was estimated to be 0.45 mg N/L, and the yield coefficient was found to be 0.15 mg biomass/mg heptadecane. Using these values, the rest of experimental data from the five columns was predicted, and the model agreed with the observations. There were some consistent discrepancies at large times between the model simulation and observed data in the cases with higher nitrate concentration. One plausible explanation for these differences could be limitation of biodegradation by reduction of the heptadecane-water interfacial area in these columns while the model uses a constant interfacial area.

Materials International Space Station Experiment-6 (MISSE-6) Atomic Oxygen Fluence Monitor Experiment

NASA Technical Reports Server (NTRS)

Banks, Bruce A.; Miller, Sharon K.; Waters, Deborah L.

2010-01-01

An atomic oxygen fluence monitor was flown as part of the Materials International Space Station Experiment-6 (MISSE-6). The monitor was designed to measure the accumulation of atomic oxygen fluence with time as it impinged upon the ram surface of the MISSE 6B Passive Experiment Container (PEC). This was an active experiment for which data was to be stored on a battery-powered data logger for post-flight retrieval and analysis. The atomic oxygen fluence measurement was accomplished by allowing atomic oxygen to erode two opposing wedges of pyrolytic graphite that partially covered a photodiode. As the wedges of pyrolytic graphite erode, the area of the photodiode that is illuminated by the Sun increases. The short circuit current, which is proportional to the area of illumination, was to be measured and recorded as a function of time. The short circuit current from a different photodiode, which was oriented in the same direction and had an unobstructed view of the Sun, was also to be recorded as a reference current. The ratio of the two separate recorded currents should bear a linear relationship with the accumulated atomic oxygen fluence and be independent of the intensity of solar illumination. Ground hyperthermal atomic oxygen exposure facilities were used to evaluate the linearity of the ratio of short circuit current to the atomic oxygen fluence. In flight, the current measurement circuitry failed to operate properly, thus the overall atomic oxygen mission fluence could only be estimated based on the physical erosion of the pyrolytic graphite wedges. The atomic oxygen fluence was calculated based on the knowledge of the space atomic oxygen erosion yield of pyrolytic graphite measured from samples on the MISSE 2. The atomic oxygen fluence monitor, the expected result and comparison of mission atomic oxygen fluence based on the erosion of the pyrolytic graphite and Kapton H atomic oxygen fluence witness samples are presented in this paper.

Preventing hypoxia-induced cell death in beta cells and islets via hydrolytically activated, oxygen-generating biomaterials

PubMed Central

Pedraza, Eileen; Coronel, Maria M.; Fraker, Christopher A.; Ricordi, Camillo; Stabler, Cherie L.

2012-01-01

A major hindrance in engineering tissues containing highly metabolically active cells is the insufficient oxygenation of these implants, which results in dying or dysfunctional cells in portions of the graft. The development of methods to increase oxygen availability within tissue-engineered implants, particularly during the early engraftment period, would serve to allay hypoxia-induced cell death. Herein, we designed and developed a hydrolytically activated oxygen-generating biomaterial in the form of polydimethylsiloxane (PDMS)-encapsulated solid calcium peroxide, PDMS-CaO2. Encapsulation of solid peroxide within hydrophobic PDMS resulted in sustained oxygen generation, whereby a single disk generated oxygen for more than 6 wk at an average rate of 0.026 mM per day. The ability of this oxygen-generating material to support cell survival was evaluated using a β cell line and pancreatic rat islets. The presence of a single PDMS-CaO2 disk eliminated hypoxia-induced cell dysfunction and death for both cell types, resulting in metabolic function and glucose-dependent insulin secretion comparable to that in normoxic controls. A single PDMS-CaO2 disk also sustained enhanced β cell proliferation for more than 3 wk under hypoxic culture conditions. Incorporation of these materials within 3D constructs illustrated the benefits of these materials to prevent the development of detrimental oxygen gradients within large implants. Mathematical simulations permitted accurate prediction of oxygen gradients within 3D constructs and highlighted conditions under which supplementation of oxygen tension would serve to benefit cellular viability. Given the generality of this platform, the translation of these materials to other cell-based implants, as well as ischemic tissues in general, is envisioned. PMID:22371586

Kinetics of growth and sugar consumption in yeasts.

PubMed

van Dijken, J P; Weusthuis, R A; Pronk, J T

1993-01-01

An overview is presented of the steady- and transient state kinetics of growth and formation of metabolic byproducts in yeasts. Saccharomyces cerevisiae is strongly inclined to perform alcoholic fermentation. Even under fully aerobic conditions, ethanol is produced by this yeast when sugars are present in excess. This so-called 'Crabtree effect' probably results from a multiplicity of factors, including the mode of sugar transport and the regulation of enzyme activities involved in respiration and alcoholic fermentation. The Crabtree effect in S. cerevisiae is not caused by an intrinsic inability to adjust its respiratory activity to high glycolytic fluxes. Under certain cultivation conditions, for example during growth in the presence of weak organic acids, very high respiration rates can be achieved by this yeast. S. cerevisiae is an exceptional yeast since, in contrast to most other species that are able to perform alcoholic fermentation, it can grow under strictly anaerobic conditions. 'Non-Saccharomyces' yeasts require a growth-limiting supply of oxygen (i.e. oxygen-limited growth conditions) to trigger alcoholic fermentation. However, complete absence of oxygen results in cessation of growth and therefore, ultimately, of alcoholic fermentation. Since it is very difficult to reproducibly achieve the right oxygen dosage in large-scale fermentations, non-Saccharomyces yeasts are therefore not suitable for large-scale alcoholic fermentation of sugar-containing waste streams. In these yeasts, alcoholic fermentation is also dependent on the type of sugar. For example, the facultatively fermentative yeast Candida utilis does not ferment maltose, not even under oxygen-limited growth conditions, although this disaccharide supports rapid oxidative growth.

Communication: A novel method for generating molecular mixtures at extreme conditions: The case of hydrogen and oxygen

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

Pravica, Michael; Sneed, Daniel; White, Melanie

2014-09-07

We have created a segregated mixture of molecular fluorine and oxygen at high pressure in a diamond anvil cell (DAC) via useful hard x-ray photochemistry. Here, a keyhole-like sample chamber was created in a stainless steel gasket to hold two segregated powders of potassium tetrafluoroborate (KBF 4) and potassium perchlorate (KClO 4) respectively in each hole at a pressure of ~3.0 GPa. Both holes were individually irradiated with synchrotron hard x-rays to release molecular fluorine and molecular oxygen, respectively. Upon irradiation of the hole containing KBF 4 molecular fluorine appeared (as evidenced via Raman spectroscopy) near the region of irradiation.more » The second hole containing KClO 4 was then irradiated and reddish-orange O 2 was observed to form. Oxygen was observed to diffuse throughout both holes whereas molecular fluorine did not. There is some evidence that oxygen difluoride (OF 2) was formed in the hole originally containing the KBF 4.« less

Thermodynamics of Oxygen Ordering in Yttrium BARIUM(2) COPPER(3) OXYGEN(6+X)

NASA Astrophysics Data System (ADS)

Schieger, Paul Richard

An apparatus has been built to study and manipulate the oxygen in high temperature superconductors. It uses the principle of cryogenically assisted volumetric titration to precisely set changes in the oxygen content of high -T_{c} samples. The apparatus has been used to study the thermodynamics of oxygen in YBa_2Cu_3O _{6 + x} in order to help determine the correct model for oxygen thermodynamics as well as to provide standard curves for materials preparation by other methods. In particular, extensive measurements have been made on the oxygen pressure isotherms as a function of x for temperatures between 450^circ C and 650^circC. The measurement technique also allows one to extract the thermodynamic response function, (partial x/ partialmu)_{T}, ( mu is the chemical potential), which is sensitive to the oxygen configuration and which can be calculated by any candidate theory of the oxygen thermodynamics. Several existing theoretical models for the oxygen ordering thermodynamics are presented and compared to the experimental results. The models considered are classed into two basic approaches: lattice gas models and defect chemical models. It is found that the lattice gas models which assume static effective pair interactions between oxygen atoms, do not fit the experimental data very well, especially in the orthorhombic phase. The defect chemical models, which incorporate additional degrees of freedom (spin and charge) due to the creation of electronic defects, fit significantly better, but make crude assumptions for the configurational entropy of oxygen atoms. Using a commonly accepted picture for the creation of mobile electron holes and unpaired spins on the copper sites, it is possible to relate these quantities in terms of short range cluster probabilities defined in mean field approximations to the 2D lattice gas models. Based upon this connection, a thermodynamical model is developed, which takes into account interactions between oxygen atoms and the additional spin and charge degrees of freedom, assuming a narrow band, high temperature limit for the motion of the charge carriers. The model, containing the nearest-neighbour oxygen interaction (0.241eV) and the single site oxygen binding energy (-0.82eV - D/2; D is the dissociation energy of an oxygen molecule) as the only adjustable parameters, is compared to experimental results for the chemical potential, kT(partial x/partialmu)_{T}, fractional site occupancies, structural phase diagram, the number of monovalent coppers, and the total number of mobile electron holes. Qualitative agreement is found for all compared quantities, and quantitative agreement is found for the chemical potential, fractional site occupancies and kT(partial x/partialmu)_ {T} in the orthorhombic phase. Improvements to the model are outlined which should result in a quantitative fit to all results, in particular the valence and hole count vs. x. In addition to illuminating what is lacking in the commonly used two dimensional lattice gas models, the theory may form the basis for accurately predicting the electron hole count of the CuO_2 plane of YBa_2Cu_3 O_{6 + x} as a function of the sample preparation conditions.

Exceptionally strong, stiff and hard hybrid material based on an elastomer and isotropically shaped ceramic nanoparticles.

PubMed

Georgopanos, Prokopios; Schneider, Gerold A; Dreyer, Axel; Handge, Ulrich A; Filiz, Volkan; Feld, Artur; Yilmaz, Ezgi D; Krekeler, Tobias; Ritter, Martin; Weller, Horst; Abetz, Volker

2017-08-04

In this work the fabrication of hard, stiff and strong nanocomposites based on polybutadiene and iron oxide nanoparticles is presented. The nanocomposites are fabricated via a general concept for mechanically superior nanocomposites not based on the brick and mortar structure, thus on globular nanoparticles with nanosized organic shells. For the fabrication of the composites oleic acid functionalized iron oxide nanoparticles are decorated via ligand exchange with an α,ω-polybutadiene dicarboxylic acid. The functionalized particles were processed at 145 °C. Since polybutadiene contains double bonds the nanocomposites obtained a crosslinked structure which was enhanced by the presence of oxygen or sulfur. It was found that the crosslinking and filler percolation yields high elastic moduli of approximately 12-20 GPa and hardness of 15-18 GPa, although the polymer volume fraction is up to 40%. We attribute our results to a catalytically enhanced crosslinking reaction of the polymer chains induced by oxygen or sulfur and to the microstructure of the nanocomposite.

One-Step Electrochemical Preparation of Multilayer Graphene Functionalized with Nitrogen

NASA Astrophysics Data System (ADS)

Ustavytska, Olena; Kurys, Yaroslav; Koshechko, Vyacheslav; Pokhodenko, Vitaly

2017-03-01

A new environmentally friendly one-step method for producing multilayer (preferably 7-9 layers) nitrogen-doped graphene (N-MLG) with a slight amount of oxygen-containing defects was developed. The approach is based on the electrochemical exfoliation of graphite electrode in the presence of azide ions under the conditions of electrolysis with pulse changing of the electrode polarization potential. It was found that usage of azide anions lead not only to the exfoliation of graphite but also to the simultaneous functionalization of graphene sheets by nitrogen atoms (as a result of electrochemical decomposition of azide anions with ammonia evolution). Composition, morphology, structure, and electrochemical properties of N-MLG were characterized by C,H,N analysis, transmission electron microscopy, atomic force microscopy, FTIR, UV-Vis, and Raman spectroscopy, as well as cyclic voltammetry. The perspective of using N-MLG as oxygen reduction reaction electrocatalyst and for the electrochemical analysis of biomarkers (dopamine, ascorbic acid, and uric acid) in their mixtures was shown.

Click-electron microscopy for imaging metabolically tagged non-protein biomolecules

PubMed Central

Ngo, John T.; Adams, Stephen R.; Deerinck, Thomas J.; Boassa, Daniela; Rodriguez-Rivera, Frances; Palida, Sakina F.; Bertozzi, Carolyn R.; Ellisman, Mark H.; Tsien, Roger Y.

2016-01-01

Electron microscopy (EM) has long been the main technique to image cell structures with nanometer resolution, but has lagged behind light microscopy in the crucial ability to make specific molecules stand out. Here we introduce “Click-EM,” a labeling technique for correlative light microscopy and EM imaging of non-protein biomolecules. In this approach, metabolic labeling substrates containing bioorthogonal functional groups are provided to cells for incorporation into biopolymers by endogenous biosynthetic machinery. The unique chemical functionality of these analogs is exploited for selective attachment of singlet oxygen-generating fluorescent dyes via bioorthogonal “click chemistry” ligations. Illumination of dye-labeled structures generates singlet oxygen to locally catalyze the polymerization of diaminobenzidine into an osmiophilic reaction product that is readily imaged by EM. We describe the application of Click-EM in imaging metabolically tagged DNA, RNA, and lipids in cultured cells and neurons, and highlight its use in tracking peptidoglycan synthesis in the Gram-positive bacterium Listeria monocytogenes. PMID:27110681

Carbon Deposition Model for Oxygen-Hydrocarbon Combustion, Volume 2

NASA Technical Reports Server (NTRS)

Hernandez, R.; Ito, J. I.; Niiya, K. Y.

1987-01-01

Presented are details of the design, fabrication, and testing of subscale hardware used in the evaluation of carbon deposition characteristics of liquid oxygen and three hydrocarbon fuels for both main chamber and preburner/gas generator operating conditions. In main chamber conditions, the deposition of carbon on the combustion chamber wall was investigated at mixture ratios of 2.0 to 4.0 and at chamber pressures of 1000 to 1500 psia. No carbon deposition on chamber walls was detected at these main chamber mixture ratios. In preburner/gas generator operating conditions, the deposition of carbon on the turbine simulator tubes was evaluated at mixture ratios of 0.20 to 0.60 and at chamber pressures of 720 to 1650 psia. The results of the tests showed carbon deposition rate to be a strong function of mixture ratio and a weak function of chamber pressure. Further analyses evaluated the operational concequences of carbon deposition on preburner/gas generator performance. This is Volume 2 of the report, which contains data plots of all the test programs.

Biochar supported nanoscale zerovalent iron composite used as persulfate activator for removing trichloroethylene.

PubMed

Yan, Jingchun; Han, Lu; Gao, Weiguo; Xue, Song; Chen, Mengfang

2015-01-01

Biochar (BC) supported nanoscale zerovalent iron (nZVI) composite was synthesized and used as an activator for persulfate to enhance the trichloroethylene (TCE) removal in aqueous solutions. The degradation efficiency of TCE (0.15mmolL(-1)) was 99.4% in the presence of nZVI/BC (4.5mmolL(-1), nZVI to BC mass ratio was 1:5) and persulfate (4.5mmolL(-1)) within 5min, which was significantly higher than that (56.6%) in nZVI-persulfate system under the same conditions. Owing to large specific surface area and oxygen-containing functional groups of BC, nZVI/BC enhanced the SO4(-) generation and accelerated TCE degradation. On the basis of the characterization and analysis data, possible activation mechanisms of the Fe(2+)/Fe(3+) (Fe(II)/Fe(III)) redox action and the electron-transfer mediator of the BC oxygen functional groups promoting the generation of SO4(-) in nZVI/BC-persulfate system were clarified. Copyright © 2014 Elsevier Ltd. All rights reserved.

Metabolic rescue in pluripotent cells from patients with mtDNA disease.

PubMed

Ma, Hong; Folmes, Clifford D L; Wu, Jun; Morey, Robert; Mora-Castilla, Sergio; Ocampo, Alejandro; Ma, Li; Poulton, Joanna; Wang, Xinjian; Ahmed, Riffat; Kang, Eunju; Lee, Yeonmi; Hayama, Tomonari; Li, Ying; Van Dyken, Crystal; Gutierrez, Nuria Marti; Tippner-Hedges, Rebecca; Koski, Amy; Mitalipov, Nargiz; Amato, Paula; Wolf, Don P; Huang, Taosheng; Terzic, Andre; Laurent, Louise C; Izpisua Belmonte, Juan Carlos; Mitalipov, Shoukhrat

2015-08-13

Mitochondria have a major role in energy production via oxidative phosphorylation, which is dependent on the expression of critical genes encoded by mitochondrial (mt)DNA. Mutations in mtDNA can cause fatal or severely debilitating disorders with limited treatment options. Clinical manifestations vary based on mutation type and heteroplasmy (that is, the relative levels of mutant and wild-type mtDNA within each cell). Here we generated genetically corrected pluripotent stem cells (PSCs) from patients with mtDNA disease. Multiple induced pluripotent stem (iPS) cell lines were derived from patients with common heteroplasmic mutations including 3243A>G, causing mitochondrial encephalomyopathy and stroke-like episodes (MELAS), and 8993T>G and 13513G>A, implicated in Leigh syndrome. Isogenic MELAS and Leigh syndrome iPS cell lines were generated containing exclusively wild-type or mutant mtDNA through spontaneous segregation of heteroplasmic mtDNA in proliferating fibroblasts. Furthermore, somatic cell nuclear transfer (SCNT) enabled replacement of mutant mtDNA from homoplasmic 8993T>G fibroblasts to generate corrected Leigh-NT1 PSCs. Although Leigh-NT1 PSCs contained donor oocyte wild-type mtDNA (human haplotype D4a) that differed from Leigh syndrome patient haplotype (F1a) at a total of 47 nucleotide sites, Leigh-NT1 cells displayed transcriptomic profiles similar to those in embryo-derived PSCs carrying wild-type mtDNA, indicative of normal nuclear-to-mitochondrial interactions. Moreover, genetically rescued patient PSCs displayed normal metabolic function compared to impaired oxygen consumption and ATP production observed in mutant cells. We conclude that both reprogramming approaches offer complementary strategies for derivation of PSCs containing exclusively wild-type mtDNA, through spontaneous segregation of heteroplasmic mtDNA in individual iPS cell lines or mitochondrial replacement by SCNT in homoplasmic mtDNA-based disease.

Cholecystokinin 1 Receptor - A Unique G Protein-Coupled Receptor Activated by Singlet Oxygen (GPCR-ABSO).

PubMed

Jiang, Hong Ning; Li, Yuan; Jiang, Wen Yi; Cui, Zong Jie

2018-01-01

Plasma membrane-delimited generation of singlet oxygen by photodynamic action with photosensitizer sulfonated aluminum phthalocyanine (SALPC) activates cholecystokinin 1 receptor (CCK1R) in pancreatic acini. Whether CCK1R retains such photooxidative singlet oxygen activation properties in other environments is not known. Genetically encoded protein photosensitizers KillerRed or mini singlet oxygen generator (miniSOG) were expressed in pancreatic acinar tumor cell line AR4-2J, CCK1R, KillerRed or miniSOG were expressed in HEK293 or CHO-K1 cells. Cold light irradiation (87 mW⋅cm -2 ) was applied to photosensitizer-expressing cells to examine photodynamic activation of CCK1R by Fura-2 fluorescent calcium imaging. When CCK1R was transduced into HEK293 cells which lack endogenous CCK1R, photodynamic action with SALPC was found to activate CCK1R in CCK1R-HEK293 cells. When KillerRed or miniSOG were transduced into AR4-2J which expresses endogenous CCK1R, KillerRed or miniSOG photodynamic action at the plasma membrane also activated CCK1R. When fused KillerRed-CCK1R was transduced into CHO-K1 cells, light irradiation activated the fused CCK1R leading to calcium oscillations. Therefore KillerRed either expressed independently, or fused with CCK1R can both activate CCK1R photodynamically. It is concluded that photodynamic singlet oxygen activation is an intrinsic property of CCK1R, independent of photosensitizer used, or CCK1R-expressing cell types. Photodynamic singlet oxygen CCK1R activation after transduction of genetically encoded photosensitizer in situ may provide a convenient way to verify intrinsic physiological functions of CCK1R in multiple CCK1R-expressing cells and tissues, or to actuate CCK1R function in CCK1R-expressing and non-expressing cell types after transduction with fused KillerRed-CCK1R.

The Antioxidation Mechanism of Polydimethylsiloxane in Oil.

PubMed

Yawata, Miho; Satoh, Tohru; Iwahashi, Maiko; Hori, Ryuji; Takeuchi, Shigeo; Shiramasa, Hiroshi; Totani, Nagao

2015-01-01

Strong and stable antioxidation effects of polydimethylsiloxane (PDMS) are widely accepted and utilized in commercial frying oil; however, the mechanism is not fully established. On the other hand, canola oil contains about 700 ppm (mg/kg-oil) of the natural antioxidant, tocopherol. Canola oil containing 0, 1 and 10 ppm added PDMS was heated at 180°C for 1 h under stirring, then left for 2-3 days at room temperature; this treatment was repeated 5 times. Compared to pure canola oil, PDMS-containing canola oil exhibited remarkably lower peroxide, p-anisidine and acid values, a lower decrease in tocopherol content but a higher oxygen content during the heating experiments, implicating low oxygen consumption for the oxidation. While PDMS has not been known to exhibit antioxidative effects at ambient temperatures, the present results show that PDMS prevents autoxidation as well as thermal oxidation. In addition, PDMS, not tocopherols, provided the major antioxidative effect during intermittent heating, and the decrease of tocopherols was significantly inhibited by PDMS. Phase contrast microscopy confirmed that PDMS contained in canola oil was suspended as particles. Also, the oxygen content in standing PDMS-containing canola oil decreased as the depth of oil increased, corresponding to the PDMS distribution, which also decreased as the depth of oil increased. Moreover, PDMS had a higher affinity for oxygen than canola oil in a mixture of canola oil/PDMS, 1:1 v/v. Thus, it is suggested that PDMS restricted the behavior of oxygen dissolved in canola oil by attracting oxygen in and around the PDMS particles, which is wholly different from the radical scavenging antioxidation of tocopherol.

Molecular-level chemistry of model single-crystal oxide surfaces with model halogenated compounds

NASA Astrophysics Data System (ADS)

Adib, Kaveh

Synchrotron-based X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption (TPD) and low energy electron diffraction (LEED) have been used to investigate, at a molecular level, the chemistry of different terminations of single crystal iron-oxide surfaces with probe molecules (CCl4 and D2O). Comparisons of the reactivity of these surfaces towards CCl4, indicate that the presence of an uncapped surface Fe cation (strong Lewis acid site) and an adjacent oxygen site capped by that cation can effect the C-Cl bond cleavage in CCl4, resulting in dissociatively adsorbed Cl-adatoms and carbon-containing fragments. If in addition to these sites, an uncapped surface oxygen (Lewis base) site is also available, the carbon-containing moiety can then move that site, coordinate itself with that uncapped oxygen, and stabilize itself. At a later step, the carbon-containing fragment may form a strong covalent bond with the uncapped oxygen and may even abstract that surface oxygen. On the other hand, if an uncapped oxygen is not available to stabilize the carbon-containing fragment, the surface coordination will not occur and upon the subsequent thermal annealing of the surface the Cl-adatoms and the carbon-containing fragments will recombine and desorb as CCl4. Finally, the presence of surface deuteroxyls blocking the strong Lewis acid and base sites of the reactive surface, passivates this surface. Such a deuteroxylated surface will be unreactive towards CCl 4. Such a molecular level understanding of the surface chemistry of metal-oxides will have applications in the areas of selective catalysis, including environmental catalysis, and chemical sensor technology.

Synthesis and characterization of covalently bound benzocaine graphite oxide derivative

NASA Astrophysics Data System (ADS)

Kabbani, Ahmad; Kabbani, Mohamad; Safadi, Khadija

2015-09-01

Graphite oxide (GO) derived materials include chemically functionalize or reduced graphene oxide (exfoliated from GO) sheets, assembled paper-like forms , and graphene-based composites GO consists of intact graphitic regions interspersed with sp3-hybridized carbons containing hydroxyl and epoxide functional groups on the top and bottom surfaces of each sheet and sp2-hybridized carbons containing carboxyl and carbonyl groups mostly at the sheet edges. Hence, GO is hydrophilic and readily disperses in water to form stable colloidal suspensions Due to the attached oxygen functional groups, GO was used to prepare different derivatives which result in some physical and chemical properties that are dramatically different from their bulk counterparts .The present work discusses the covalent cross linking of graphite oxide to benzocaine or ethyl ester of para-aminobenzoic acid,structure I,used in many over-the-counter ointment drug.Synthesis is done via diazotization of the amino group.The product is characterized via IR,Raman, X-ray photoelectron spectroscopy as well as electron microscopy.

Geometric and compositional factors on critical current density in YBa2Cu3O7‑δ films containing nanorods

NASA Astrophysics Data System (ADS)

Horide, Tomoya; Nagao, Sho; Izutsu, Ryosuke; Ishimaru, Manabu; Kita, Ryusuke; Matsumoto, Kaname

2018-06-01

Critical current density (J c) was investigated in YBa2Cu3O7‑δ films containing nanorods prepared with various nanorod materials, with variation of nanorod content, substrate temperature, and oxidization condition. Three types of compositional situation were realized: films containing strain induced oxygen vacancies; fully oxidized films containing cation compositional deviation; and oxygen deficient films. Normalized J c‑B behavior was determined via the matching field, which is a geometric factor, regardless of the compositional details. A J c‑critical temperature (T c) relation depending on distribution and fraction of compositional deviation (cation compositional deviation and strain induced oxygen vacancies) was found: the J c values decreased with decreasing T c due to the effect of T c on nanorod pinning strength in the fully oxidized films; J c decreased with decreasing oxygen pressure in the film cooling process after film deposition in spite of T c remaining almost the same, due to reduction of the effective area for current flow in the oxygen deficient films. Thus, a J c landscape based on geometric and compositional factors was obtained. The study highlights the importance of the J c‑T c analysis in the understanding of J c in YBa2Cu3O7‑δ films containing nanorods.

Phase separation of bio-oil produced by co-pyrolysis of corn cobs and polypropylene

NASA Astrophysics Data System (ADS)

Supramono, D.; Julianto; Haqqyana; Setiadi, H.; Nasikin, M.

2017-11-01

In co-pyrolysis of biomass-plastics, bio-oil produced contains both oxygenated and non-oxygenated compounds. High oxygen composition is responsible for instability and low heating value of bio-oil and high acid content for corrosiveness. Aims of the present work are to evaluate possibilities of achieving phase separation between oxygenated and non-oxygenated compounds in bio-oil using a proposed stirred tank reactor and to achieve synergistic effects on bio-oil yield and non-oxygenated compound layer yield. Separation of bio-oil into two layers, i.e. that containing oxygenated compounds (polar phase) and non-oxygenated compounds (non-polar phase) is important to obtain pure non-polar phase ready for the next processing of hydrogenation and used directly as bio-fuel. There has been no research work on co-pyrolysis of biomass-plastic considering possibility of phase separation of bio-oil. The present work is proposing a stirred tank reactor for co-pyrolysis with nitrogen injection, which is capable of tailoring co-pyrolysis conditions leading to low viscosity and viscosity asymmetry, which induce phase separation between polar phase and non-polar phase. The proposed reactor is capable of generating synergistic effect on bio-oil and non-polar yields as the composition of PP in feed is more than 25% weight in which non-polar layers contain only alkanes, alkenes, cycloalkanes and cycloalkenes.

Prolonged cold storage of red blood cells by oxygen removal and additive usage

DOEpatents

Bitensky, M.W.; Yoshida, Tatsuro

1998-08-04

Prolonged cold storage of red blood cells by oxygen removal and additive usage. A cost-effective, 4 C storage procedure that preserves red cell quality and prolongs post-transfusion in vivo survival is described. The improved in vivo survival and the preservation of adenosine triphosphate levels, along with reduction in hemolysis and membrane vesicle production of red blood cells stored at 4 C for prolonged periods of time, is achieved by reducing the oxygen level therein at the time of storage; in particular, by flushing the cells with an inert gas, and storing them in an aqueous solution which includes adenine, dextrose, mannitol, citrate ion, and dihydrogen phosphate ion, but no sodium chloride, in an oxygen-permeable container which is located in an oxygen-free environment containing oxygen-scavenging materials. 8 figs.

Prolonged cold storage of red blood cells by oxygen removal and additive usage

DOEpatents

Bitensky, Mark W.; Yoshida, Tatsuro

1998-01-01

Prolonged cold storage of red blood cells by oxygen removal and additive usage. A cost-effective, 4.degree. C. storage procedure that preserves red cell quality and prolongs post-transfusion in vivo survival is described. The improved in vivo survival and the preservation of adenosine triphosphate levels, along with reduction in hemolysis and membrane vesicle production of red blood cells stored at 4.degree. C. for prolonged periods of time, is achieved by reducing the oxygen level therein at the time of storage; in particular, by flushing the cells with an inert gas, and storing them in an aqueous solution which includes adenine, dextrose, mannitol, citrate ion, and dihydrogen phosphate ion, but no sodium chloride, in an oxygen-permeable container which is located in an oxygen-free environment containing oxygen-scavenging materials.

Oxygen ion-conducting dense ceramic

DOEpatents

Balachandran, Uthamalingam; Kleefisch, Mark S.; Kobylinski, Thaddeus P.; Morissette, Sherry L.; Pei, Shiyou

1996-01-01

Preparation, structure, and properties of mixed metal oxide compositions containing at least strontium, cobalt, iron and oxygen are described. The crystalline mixed metal oxide compositions of this invention have, for example, structure represented by Sr.sub..alpha. (Fe.sub.1-x Co.sub.x).sub..alpha.+.beta. O.sub..delta. where x is a number in a range from 0.01 to about 1, .alpha. is a number in a range from about 1 to about 4, .beta. is a number in a range upward from 0 to about 20, and .delta. is a number which renders the compound charge neutral, and wherein the composition has a non-perovskite structure. Use of the mixed metal oxides in dense ceramic membranes which exhibit oxygen ionic conductivity and selective oxygen separation, are described as well as their use in separation of oxygen from an oxygen-containing gaseous mixture.

Oxygen ion-conducting dense ceramic

DOEpatents

Balachandran, Uthamalingam; Kleefisch, Mark S.; Kobylinski, Thaddeus P.; Morissette, Sherry L.; Pei, Shiyou

1997-01-01

Preparation, structure, and properties of mixed metal oxide compositions containing at least strontium, cobalt, iron and oxygen are described. The crystalline mixed metal oxide compositions of this invention have, for example, structure represented by Sr.sub..alpha. (Fe.sub.1-x Co.sub.x).sub..alpha.+.beta. O.sub..delta. where x is a number in a range from 0.01 to about 1, .alpha. is a number in a range from about 1 to about 4, .beta. is a number in a range upward from 0 to about 20, and .delta. is a number which renders the compound charge neutral, and wherein the composition has a non-perovskite structure. Use of the mixed metal oxides in dense ceramic membranes which exhibit oxygen ionic conductivity and selective oxygen separation, are described as well as their use in separation of oxygen from an oxygen-containing gaseous mixture.

Numerical Optimization of Density Functional Tight Binding Models: Application to Molecules Containing Carbon, Hydrogen, Nitrogen, and Oxygen

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

Krishnapriyan, A.; Yang, P.; Niklasson, A. M. N.

New parametrizations for semiempirical density functional tight binding (DFTB) theory have been developed by the numerical optimization of adjustable parameters to minimize errors in the atomization energy and interatomic forces with respect to ab initio calculated data. Initial guesses for the radial dependences of the Slater- Koster bond integrals and overlap integrals were obtained from minimum basis density functional theory calculations. The radial dependences of the pair potentials and the bond and overlap integrals were represented by simple analytic functions. The adjustable parameters in these functions were optimized by simulated annealing and steepest descent algorithms to minimize the value ofmore » an objective function that quantifies the error between the DFTB model and ab initio calculated data. The accuracy and transferability of the resulting DFTB models for the C, H, N, and O system were assessed by comparing the predicted atomization energies and equilibrium molecular geometries of small molecules that were not included in the training data from DFTB to ab initio data. The DFTB models provide accurate predictions of the properties of hydrocarbons and more complex molecules containing C, H, N, and O.« less

Numerical Optimization of Density Functional Tight Binding Models: Application to Molecules Containing Carbon, Hydrogen, Nitrogen, and Oxygen

DOE PAGES

Krishnapriyan, A.; Yang, P.; Niklasson, A. M. N.; ...

2017-10-17

New parametrizations for semiempirical density functional tight binding (DFTB) theory have been developed by the numerical optimization of adjustable parameters to minimize errors in the atomization energy and interatomic forces with respect to ab initio calculated data. Initial guesses for the radial dependences of the Slater- Koster bond integrals and overlap integrals were obtained from minimum basis density functional theory calculations. The radial dependences of the pair potentials and the bond and overlap integrals were represented by simple analytic functions. The adjustable parameters in these functions were optimized by simulated annealing and steepest descent algorithms to minimize the value ofmore » an objective function that quantifies the error between the DFTB model and ab initio calculated data. The accuracy and transferability of the resulting DFTB models for the C, H, N, and O system were assessed by comparing the predicted atomization energies and equilibrium molecular geometries of small molecules that were not included in the training data from DFTB to ab initio data. The DFTB models provide accurate predictions of the properties of hydrocarbons and more complex molecules containing C, H, N, and O.« less

The levels and kinetics of oxygen tension detectable at the surface of human dermal fibroblast cultures.

PubMed

Tokuda, Y; Crane, S; Yamaguchi, Y; Zhou, L; Falanga, V

2000-03-01

Low oxygen tension has recently been shown to stimulate cell growth and clonal expansion, as well as synthesis and transcription of certain growth factors and extracellular matrix components. These results have been obtained by exposing cell cultures to a hypoxic environment. Using an oxygen probe, we have now studied how experimental conditions affect the oxygen tension detectable at the cell surface. Dissolved oxygen tension was directly related to the height of the medium above the cell surface (r = 0.8793, P = 0.021), but was constant when no cells were present in the flask (r = -0. 9732, P = 0.001). In both human dermal fibroblasts and NIH/3T3 cultures, oxygen tension decreased linearly as cell density increased (r = -0.835, P < 0.0001; r = -0.916, P < 0.0001, respectively). When human dermal fibroblasts were exposed to 2% O(2), maximum hypoxic levels (0 mmHg) were achieved within approximately 15 min, and the recovery time was within a similar time frame. The addition of rotenone, an inhibitor of cellular respiration, blocked this decrease in oxygen tension at the cell surface, suggesting that cellular consumption of oxygen is responsible for the decline. Finally, we examined the cell-surface oxygen tension in control and acutely wounded human skin equivalents (HSE), consisting of a keratinocyte layer over a type I collagen matrix containing fibroblasts. We found that oxygen tension dropped significantly (P < 0.0001) in acutely wounded areas of HSE as compared to unwounded areas of HSE and that this drop was prevented by the addition of mitomycin C. These results indicate that cell-surface oxygen tension is indirectly related to cell density, and that the amount of detectable oxygen at the cell surface is a function of cell density, the oxygen tension in the incubator, and increased cellular activity, as occurs after injury. Copyright 2000 Wiley-Liss, Inc.

Kinetics of nitric oxide and oxygen gases on porous Y-stabilized ZrO2-based sensors.

PubMed

Killa, Sajin; Cui, Ling; Murray, Erica P; Mainardi, Daniela S

2013-08-16

Using impedance spectroscopy the electrical response of sensors with various porous Y-stabilized ZrO2 (YSZ) microstructures was measured for gas concentrations containing 0-100 ppm NO with 10.5%O2 at temperatures ranging from 600-700 °C. The impedance response increased substantially as the sensor porosity increased from 46%-50%. Activation energies calculated based on data from the impedance measurements increased in magnitude (97.4-104.9 kJ/mol for 100 ppm NO) with respect to increasing YSZ porosity. Analysis of the oxygen partial pressure dependence of the sensors suggested that dissociative adsorption was the dominant rate limiting. The PWC/DNP theory level was used to investigate the gas-phase energy barrier of the 2NO+O2 → 2NO2 reaction on a 56-atom YSZ/Au model cluster using Density Functional Theory and Linear Synchronous Transit/Quadratic Synchronous Transit calculations. The reaction path shows oxygen surface reactions that begin with NO association with adsorbed O2 on a Zr surface site, followed by O2 dissociative adsorption, atomic oxygen diffusion, and further NO2 formation. The free energy barrier was calculated to be 181.7 kJ/mol at PWC/DNP. A qualitative comparison with the extrapolated data at 62% ± 2% porosity representing the YSZ model cluster indicates that the calculated barriers are in reasonable agreement with experiments, especially when the RPBE functional is used.

30 CFR 57.5015 - Oxygen deficiency.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Oxygen deficiency. 57.5015 Section 57.5015..., Physical Agents, and Diesel Particulate Matter Air Quality-Underground Only § 57.5015 Oxygen deficiency. Air in all active workings shall contain at least 19.5 volume percent oxygen. Radiation—Underground...

30 CFR 57.5015 - Oxygen deficiency.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Oxygen deficiency. 57.5015 Section 57.5015..., Physical Agents, and Diesel Particulate Matter Air Quality-Underground Only § 57.5015 Oxygen deficiency. Air in all active workings shall contain at least 19.5 volume percent oxygen. Radiation—Underground...