Note: This page contains sample records for the topic chemical oxygen demand from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

CORRELATION BETWEEN BIOCHEMICAL OXYGEN DEMAND (BOD) AND CHEMICAL OXYGEN DEMAND (COD) FOR DIFFERENT INDUSTRIAL WASTE WATERS  

Microsoft Academic Search

Biochemical oxygen demand (BOD) and chemical oxygen demand (COD) are two important parameters used in estimating the degree of organic pollution in waste waters. The determination of BOD is tedious and time consuming and depends on biochemical factors while COD is precise, time saving and completely chemical in nature. COD is not dependent on biochemical factors. Relationship between 3-day BOD

AMARASINGHE H. ANUSHA; JAYATUNGA Y. N. AMARAMALI

2

Biochemical Oxygen Demand of Shell Chemicals with Cover Letter.  

National Technical Information Service (NTIS)

Measurement of the biochemical oxygen demand (BOD) of discharged waste water is required by the authorities in several countries to characteristics the concentration of polluting (usually organic) material in the water. It is therefore of importance to Sh...

1982-01-01

3

Estimation of Biological Oxygen Demand and Chemical Oxygen Demand for Combined Sewer Systems Using Synchronous Fluorescence Spectra  

PubMed Central

Real-time monitoring of water quality for sewer system is required for efficient sewer network design because it provides information on the precise loading of pollutant to wastewater treatment facilities and the impact of loading on receiving water. In this study, synchronous fluorescence spectra and its first derivatives were investigated using a number of wastewater samples collected in sewer systems in urban and non-urban areas, and the optimum fluorescence feature was explored for the estimation of biochemical oxygen demand (BOD) and chemical oxygen demand (COD) concentrations of sewer samples. The temporal variations in BOD and COD showed a regular pattern for urban areas whereas they were relatively irregular for non-urban areas. Irrespective of the sewer pipes and the types of the areas, two distinct peaks were identified from the synchronous fluorescence spectra, which correspond to protein-like fluorescence (PLF) and humic-like fluorescence (HLF), respectively. HLF in sewer samples appears to be associated with fluorescent whitening agents. Five fluorescence characteristics were selected from the synchronous spectra and the first-derivatives. Among the selected fluorescence indices, a peak in the PLF region (i.e., Index I) showed the highest correlation coefficient with both BOD and COD. A multiple regression approach based on suspended solid (SS) and Index I used to compensate for the contribution of SS to BOD and COD revealed an improvement in the estimation capability, showing good correlation coefficients of 0.92 and 0.94 for BOD and COD, respectively.

Hur, Jin; Lee, Bo-Mi; Lee, Tae-Hwan; Park, Dae-Hee

2010-01-01

4

Photocatalytic sensor for the determination of chemical oxygen demand using flow injection analysis  

Microsoft Academic Search

A photocatalytic sensor for the determination of chemical oxygen demand (COD) with flow injection analysis (FIA) based on the photocatalysis of organic compounds in the presence of titanium dioxide (TiO2) beads in a photochemical column is described. The sensor was developed in conjunction with TiO2 beads in the photochemical column and with an oxygen electrode as the sensing part. The

Yoon-Chang Kim; Satoshi Sasaki; Kazuyoshi Yano; Kazunori Ikebukuro; Kazuhito Hashimoto; Isao Karube

2001-01-01

5

Chemiluminescence system for automatic determination of chemical oxygen demand using flow injection analysis  

Microsoft Academic Search

A novel chemiluminescence (CL) system for automatic determination of chemical oxygen demand (COD) combined with flow injection analysis is proposed in this paper. In this system, potassium permanganate is reduced to Mn2+ which is first adsorbed on a strongly acid cation-exchange resin mini-column to be concentrated during chemical oxidation of the organic compounds at room temperature, while the excessive MnO4?

Baoxin Li; Zhujun Zhang; Juan Wang; Chunli Xu

2003-01-01

6

A nano-copper electrochemical sensor for sensitive detection of chemical oxygen demand  

Microsoft Academic Search

Copper nanoparticle (nano-Cu) was electrodeposited on the surface of Cu disk electrode under ?1V for 60s, and then used to construct an electrochemical sensor for chemical oxygen demand (COD). The electrochemical oxidation behavior of glycine, a standard compound for evaluating the COD, was investigated. The potential shifts negatively, and the current increases greatly at the surface of nano-Cu, indicating remarkable

Jinquan Yang; Jianwei Chen; Yikai Zhou; Kangbing Wu

2011-01-01

7

Correlating Biochemical and Chemical Oxygen Demand of Effluents - A Case Study of Selected Industries in Kumasi, Ghana  

Microsoft Academic Search

The study aims at establishing an empirical correla tion between biochemical oxygen demand (BOD 5) and chemical oxygen demand (COD) of effluents from selected industries in the Kumasi Metropolis to facilitate speed y effluent quality assessment or optimal process control. Hour ly effluent samples were collected for an 8-h perio d three times per week for analysis of the principal

F. K. Attiogbe; Mary Glover-Amengor; K. T. Nyadziehe

8

Replacing dichromate with hydrogen peroxide in the chemical oxygen demand (COD) test.  

PubMed

The widely used standard method for chemical oxygen demand (COD) involves hazardous chromium species, and its two-hour heating protocol entails a substantial amount of energy expenditure. In the present work we report a proof of concept for a major modification of this method in the range 10-800 mgCOD/L, whereby H2O2 is proposed as a replacement oxidizer. This modification not only reduces the use of unsafe chromium species but also allows for the use of milder conditions that decrease the total energy outlay. The results are comparable with those obtained either with the standard method or with a commercial Hach® kit. PMID:22797236

Carbajal-Palacios, Patricia; Balderas-Hernández, Patricia; Ibanez, Jorge G; Roa-Morales, Gabriela

2012-01-01

9

Determination of Oxygen Demand  

NASA Astrophysics Data System (ADS)

Oxygen demand is a commonly used parameter to evaluate the potential effect of organic pollutants on either a wastewater treatment process or a receiving water body. Because microorganisms utilize these organic materials, the concentration of dissolved oxygen is greatly depleted from the water. The oxygen depletion in the environment can have a detrimental effect on fish and plant life.

Hang, Yong D.

10

Evaluation of a static granular bed reactor using a chemical oxygen demand balance and mathematical modeling.  

PubMed

In order to evaluate the static granular bed reactor (SGBR), a chemical oxygen demand (COD) balance was used along with a mathematical model. The SGBR was operated with an organic loading rate (OLR) ranging from 0.8 to 5.5 kg/m(3) day at 24°C. The average COD removal efficiency was 87.4%, and the removal efficiencies of COD, carbohydrates, and proteins increased with an OLR, while the lipids removal efficiency was not a function of an OLR. From the results of the COD balance, the yield of biomass increased with an OLR. The SGBR was modeled using the general transport equation considering advection, diffusion, and degradation by microorganisms, and the first-order reaction rate constant was 0.0166/day. The simulation results were in excellent agreement with experimental data. In addition, the SGBR model provided mechanistic insight into why the COD removal efficiency in the SGBR is proportional to an OLR. PMID:21470852

Lim, Seung Joo; Fox, Peter

2011-03-15

11

Rapid Determination of the Chemical Oxygen Demand in Water with the Use of High-Temperature Solid-Electrolyte Cells  

Microsoft Academic Search

A new procedure is proposed for the determination of the oxidazibility of organic and inorganic matter in water (an analogue of the chemical oxygen demand (COD)). The procedure is based on high-temperature oxidation in a controlled binary oxygen–inert gas mixture and the determination of the amount of oxygen consumed for oxidation in a solid-electrolyte cell. A new design for the

B. K. Zuev; A. A. Korotkov; V. G. Filonenko; A. N. Mashkovtsev; V. P. Zvolinskii

2004-01-01

12

Dissolved Oxygen Demand of Reduced Chemical Species in the Water Column of Sebasticook Lake, Maine.  

National Technical Information Service (NTIS)

Fifty water column profiles were sampled at Sebasticook Lake, Penobscot County, Maine to determine the impact of reduced chemical species on the dissolved oxygen content of this culturally eutrophic lake. Reduced chemical species measured were CH4, Fe(+2)...

F. P. Liotta

1979-01-01

13

Grey and neural network prediction of suspended solids and chemical oxygen demand in hospital wastewater treatment plant effluent  

Microsoft Academic Search

Grey model (GM) and artificial neural network (ANN) was employed to predict suspended solids (SS) and chemical oxygen demand (COD) in the effluent from sequence batch reactors of a hospital wastewater treatment plant (HWWTP). The results indicated that the minimum mean absolute percentage errors (MAPEs) of 23.14% and 51.73% for SS and COD could be achieved using genetic algorithm ANN

T. Y. Pai; Y. P. Tsai; H. M. Lo; C. H. Tsai; C. Y. Lin

2007-01-01

14

Determination of chemical oxygen demand (COD) using ultrasound digestion and oxidation-reduction potential-based titration  

Microsoft Academic Search

A new method for determining wastewater chemical oxygen demand (COD) using ultrasonic digestion and titration based on oxidation reduction potential (ORP) was developed. COD values of potassium hydrogen phthalate solution obtained by ultrasonic digestion were well matched with those obtained using Standard Methods. When applied to determine COD of real wastewater collected from a local treatment plant, results from the

Hyunook Kim; Honglae Lim; Mark F. Colosimo

2007-01-01

15

A portable photoelectrochemical probe for rapid determination of chemical oxygen demand in wastewaters.  

PubMed

A photoelectrochemical probe for rapid determination of chemical oxygen demand (COD) is developed using a nanostructured mixed-phase TiO2 photoanode, namely PeCOD probe. A UV-LED light source and a USB mircroelectrochemical station are powered and controlled by a laptop computer, which makes the probe portable for onsite COD analyses. The photoelectrochemical measurement of COD was optimized in terms of light intensity, applied bias, and pH. Under the optimized conditions, the net steady state currents originated from the oxidation of organic compounds were found to be directly proportional to COD concentrations. A practical detection limit of 0.2 ppm COD and a linear range of 0-120 ppm COD were achieved. The analytical method using the portable PeCOD probe has the advantages of being rapid, low cost, robust, user-friendly, and environmental friendly. It has been successfully applied to determine the COD values of the synthetic samples consisting of potassium hydrogen phthalate, D-glucose, glutamic acid, glutaric acid, succinic acid, and malonic acid, and real samples from various industries, such as bakery, oil and grease manufacturer, poultry, hotel, fine food factory, and fresh food producer, commercial bread manufacturer. Excellent agreement between the proposed method and the conventional COD method (dichromate) was achieved. PMID:19921898

Zhang, Shanqing; Li, Lihong; Zhao, Huijun

2009-10-15

16

Recalcitrant organic compounds (chemical oxygen demand sources) in biologically treated pulp and paper mill effluents: Their fate and environmental impact in receiving waters  

Microsoft Academic Search

Most North American pulp and paper mills now biologically treat (biotreat) their liquid effluent. However, treated water still contains effluent-derived recalcitrant organic material (EROM), measured as chemical oxygen demand (COD), for which emission limits exist in Europe and are being considered in the US. Production of microbially resistant, dissolved natural organic material (NOM) typically found in Canadian stream and lake

F. Archibald; L. Roy-Arcand; M. Methot; L. Valeanu

1998-01-01

17

Quantum dots assisted photocatalysis for the chemiluminometric determination of chemical oxygen demand using a single interface flow system.  

PubMed

A novel flow method for the determination of chemical oxygen demand (COD) is proposed in this work. It relies on the combination of a fully automated single interface flow system, an on-line UV photocatalytic unit and quantum dot (QD) nanotechnology. The developed approach takes advantage of CdTe nanocrystals capacity to generate strong oxidizing species upon irradiation with UV light, which fostered a fast catalytic degradation of the organic compounds. Luminol was used as a chemiluminescence (CL) probe for indirect COD assessment, since it is easily oxidized by the QD generated species yielding a strong CL emission that is quenched in the presence of the organic matter. The proposed methodology allowed the determination of COD concentrations between 1 and 35 mg L(-1), with good precision (R.S.D.<1.1%, n=3) and a sampling frequency of about 33 h(-1). The procedure was applied to the determination of COD in wastewater certified reference materials and the obtained results showed an excellent agreement with the certified values. PMID:21704774

Silvestre, Cristina I C; Frigerio, Christian; Santos, João L M; Lima, José L F C

2011-05-20

18

Water column oxygen demand and sediment oxygen flux: patterns of oxygen depletion in tidal creeks  

Microsoft Academic Search

Low dissolved oxygen (DO) levels often occur during summer in tidal creeks along the southeastern coast of the USA. We analyzed\\u000a rates of oxygen loss as water-column biochemical oxygen demand (BOD5) and sediment oxygen flux (SOF) at selected tidal creek sites monthly over a 1-year period. Ancillary physical, chemical\\u000a and biological data were collected to identify factors related to oxygen

Tara A. MacPherson; Lawrence B. Cahoon; Michael A. Mallin

2007-01-01

19

Determination of chemical oxygen demand of nitrogenous organic compounds in wastewater using synergetic photoelectrocatalytic oxidation effect at TiO2 nanostructured electrode.  

PubMed

Chemical oxygen demand (COD) is one of the most important parameters in water quality assessment and monitoring. The natural degradation of nitrogenous organic compounds (NOCs) in water requires significant amounts of oxygen. In the determination of standard COD however, NOCs are persistent compounds that cannot be completely oxidized even in the most oxidative chemical environments, i.e. the reaction media that contain high concentrations of dichromate in strong acid at high temperature. Consequently, the measured COD values of wastewater samples containing NOCs are commonly lower than theoretical COD values and do not reflect the actual oxygen demand of the water body. This problem is partially alleviated when the photoelectrochemical method for COD determination (PeCOD) based on nanostructured TiO(2) photoanode is utilized. To completely overcome this problem, a synergetic photoelectrochemical oxidation effect in thin layer cells is used to achieve complete oxidation of NOCs. This is done by the simple addition of a hydroxyl organic compound (i.e. glucose) into the test sample before the PeCOD measurement. Preliminary experimental results demonstrate that the synergetic PeCOD method provides an effective and reliable means to measure COD values of NOC-containing pollutants without the need for toxic or expensive reagents. PMID:23140953

Li, Lihong; Zhang, Shanqing; Li, Guiying; Zhao, Huijun

2012-10-12

20

Dissolved Oxygen and Biochemical Oxygen Demand  

NSDL National Science Digital Library

This Environmental Protection Agency (EPA) website provides general information about dissolved oxygen, including what it is, sampling and equipment considerations, and sampling and analysis protocols. The site also features a chart of dissolved oxygen solubility as a function of temperature.

2010-03-02

21

Dissolved Oxygen and Biochemical Oxygen Demand  

NSDL National Science Digital Library

This EPA website provides general information about dissolved oxygen, including what it is, sampling and equipment considerations, and sampling and analysis protocols. The site also features a chart of dissolved oxygen solubility as a function of temperature.

Agency, U. S.

22

Chemical oxygen generation.  

PubMed

While pressurized oxygen in tank form, as well as oxygen concentrators, are ubiquitous in civilian healthcare in developed countries for medical use, there are a number of settings where use of these oxygen delivery platforms is problematic. These settings include but are not limited to combat casualty care and healthcare provided in extreme rural environments in undeveloped countries. Furthermore, there are a number of settings where delivery of oxygen other than the pulmonary route to oxygenate tissues would be of value, including severe lung injury, airway obstruction, and others. This paper provides a brief overview of the previous and current attempts to utilize chemical oxygen production strategies to enhance systemic oxygenation. While promising, the routine use of chemically produced oxygen continues to pose significant engineering and physiologic challenges. PMID:23271828

Ward, Kevin R; Huvard, Gary S; McHugh, Mark; Mallepally, Rajender R; Imbruce, Richard

2013-01-01

23

Disposable sensor for biochemical oxygen demand  

Microsoft Academic Search

Disposable-type microbial sensors were prepared for the determination of biochemical oxygen demand (BOD). The yeast, Trichosporon cutaneum, was directly immobilized on the surface of miniature oxygen electrodes using an ultraviolet crosslinking resin (ENT-3400).\\u000a The oxygen electrodes (15?mm× 2?mm×0.4?mm) were made on silicon substrates using micromachining techniques. They were Clark-type\\u000a two-electrode systems with?1021?mV applied to the working electrode. Typical response times

Z. Yang; H. Suzuki; S. Sasaki; I. Karube

1996-01-01

24

ENHANCED COD (CHEMICAL OXYGEN DEMAND) REMOVAL FROM PHARMACEUTICAL WASTEWATER USING POWDERED ACTIVATED CARBON ADDITION TO AN ACTIVATED SLUDGE SYSTEM  

EPA Science Inventory

Wastewater generated by the pharmaceutical manufacturing point source Sub-categories A (Fermentation Products) and C (Chemical Synthesis Products) are characterized by high COD concentrations (10,000 mg/l and higher). Plants in these subcategories typically employ secondary treat...

25

Treatment of a slaughterhouse wastewater: effect of internal recycle rate on chemical oxygen demand, total Kjeldahl nitrogen and total phosphorus removal.  

PubMed

This study investigated the ability of an anaerobic/anoxic/oxic (A2/O) system to treat a slaughterhouse wastewater. The system employed two identical continuous-flow reactors (101 total liquid volume each) running in parallel with the main operational variable, being the internal recycle (IR) rate. The chemical oxygen demand (COD), total Kjeldahl nitrogen (TKN) and total phosphorus (TP) performance was evaluated as the IR flowrate was increased from a Q of 151d(-1) to 4Q at a system hydraulic retention time of 16 h and a solids retention time of 10 d. The COD:TKN and COD:TP ratios were 8.2:1 and 54:1, which supported both nitrogen and phosphorus removal. For all IR multiples of Q, the COD removal was in excess of 90%. The TKN removal showed a modest improvement (a 4-5% increase, depending on the dissolved oxygen (DO)) as the IR doubled from Q to 2Q, but no further increase was observed at the 4Q IR rate. The TP removal reached its optimum (around 85%-89% (again depending on the DO)) at the 2Q rate. PMID:22439562

Fongsatitkul, P; Wareham, D G; Elefsiniotis, P; Charoensuk, P

2011-12-01

26

Combined coagulation-flocculation and sequencing batch reactor with phosphorus adjustment for the treatment of high-strength landfill leachate: experimental kinetics and chemical oxygen demand fractionation.  

PubMed

The treatability of high-strength landfill leachate is challenging and relatively limited. This study examines the feasibility of treating high-strength landfill leachate (chemical oxygen demand [COD]: 7,760-11,770 mg/L, biochemical oxygen demand [BOD5]: 2,760-3,569 mg/L, total nitrogen [TN] = 980-1,160 mg/L) using a sequencing batch reactor (SBR) preceded by a coagulation-flocculation process with phosphorus nutritional balance under various mixing and aeration patterns. Simulations were also conducted to define kinetic parameters and COD fractionation. Removal efficiencies reached 89% for BOD5, 60% for COD, and 72% for TN, similar to and better than reported studies, albeit with a relatively lower hydraulic retention time (HRT) and solid retention time (SRT). The coupled experimental and simulation results contribute in filling a gap toward managing high-strength landfill leachate and providing guidelines for corresponding SBR applications. Implications: The treatability of high-strength landfill leachate, which is challenging and relatively limited, was demonstrated using a combined coagulation-flocculation with SBR technology and nutrient balance adjustment. The most suitable coagulant, kinetic design parameters, and COD fractionation were defined using coupled experimental and simulation results contributing in filling a gap toward managing high-strength leachate by providing guidelines for corresponding SBR applications and anticipating potential constraints related to the non-biodegradable COD fraction. In this context, while the combined coagulation-flocculation and SBR process improved removal efficiencies, posttreatment may be required for high-strength leachate, depending on discharge standards and ultimate usage of the treated leachate. PMID:23786150

El-Fadel, M; Matar, F; Hashisho, J

2013-05-01

27

Ozonation of sludge-press liquors: Determination of carbonyl compounds by the PFBOA method and the effect on the chemical oxygen demand  

SciTech Connect

The European Community Urban Waste Water Treatment Directive, May 1991, requires water service companies to provide sufficient wastewater treatment to meet a new limit set for the Chemical Oxygen Demand (COD) in final effluent and new legislation has placed limits on the levels of COD that can be discharged from wastewater treatment works using secondary treatment processes. The current permitted upper level for COD in the final effluent is 125 mg per litre. Ozone is a strong oxidant and disinfectant and in contrast to chlorine, does not produce chlorinated by-products from its reaction with natural organic matter in water. In spite of the successful use of ozone for the treatment of potable waters since the early part of the century very few studies have been undertaken into possible chemical by-products which might arise from ozonation. Since the amount of ozone applied is always lower than that required to oxidize all the organic matter to carbon dioxide and water, a number of semi-oxidation products such as aromatic, phenolic and aliphatic carboxylic acids, aldehydes and ketones can be expected to be formed. The ozonation of sludge-press liquors and the resultant effect on COD was investigated. The concentration of carbonyl compounds was analyzed using O-(pentafluorobenzyl) hydroxylamine (PFBOA) as a derivatising agent in Gas Chromatographic (GC) determination.

Boyle, L.L.; McCullough, N.H. [Univ. Chemical Lab., Kent (United Kingdom); Poppelen, P. van [Southern Water Services Limited, Kent (United Kingdom)

1996-12-31

28

Recalcitrant organic compounds (chemical oxygen demand sources) in biologically treated pulp and paper mill effluents: Their fate and environmental impact in receiving waters  

SciTech Connect

Most North American pulp and paper mills now biologically treat (biotreat) their liquid effluent. However, treated water still contains effluent-derived recalcitrant organic material (EROM), measured as chemical oxygen demand (COD), for which emission limits exist in Europe and are being considered in the US. Production of microbially resistant, dissolved natural organic material (NOM) typically found in Canadian stream and lake waters occurs slowly under gentle conditions, while mill EROM is generated from lignocellulosics by faster and harsher processes. Similarity of the environmental effects of NOM and pulp and paper mill EROM are examined. Changes occurring over 4 months in biologically treated effluent from two modern Canadian mills and lake NOM when sealed in gas- and light-permeable bags and placed in a pristine Quebec lake are reported. Addition of microbial co-metabolites significantly improved the dark mineralization of organochlorines surviving mill biological treatment. Mill EROM was light sensitive, nonacutely toxic in the Microtox assay, and similar to NOM in the surrounding lake in most bulk properties. There was no evidence to suggest that placing specific limits on mill EROM (COD) emissions would be environmentally beneficial.

Archibald, F.; Roy-Arcand, L.; Methot, M.; Valeanu, L.

1998-11-01

29

A pilot scale trickling filter with pebble gravel as media and its performance to remove chemical oxygen demand from synthetic brewery wastewater.  

PubMed

Evaluating the performance of a biotrickling filter for the treatment of wastewaters produced by a company manufacturing beer was the aim of this study. A pilot scale trickling filter filled with gravel was used as the experimental biofilter. Pilot scale plant experiments were made to evaluate the performance of the trickling filter aerobic and anaerobic biofilm systems for removal of chemical oxygen demand (COD) and nutrients from synthetic brewery wastewater. Performance evaluation data of the trickling filter were generated under different experimental conditions. The trickling filter had an average efficiency of (86.81±6.95)% as the hydraulic loading rate increased from 4.0 to 6.4 m(3)/(m(2)?d). Various COD concentrations were used to adjust organic loading rates from 1.5 to 4.5 kg COD/(m(3)?d). An average COD removal efficiency of (85.10±6.40)% was achieved in all wastewater concentrations at a hydraulic loading of 6.4 m(3)/(m(2)?d). The results lead to a design organic load of 1.5 kg COD/(m(3)?d) to reach an effluent COD in the range of 50-120 mg/L. As can be concluded from the results of this study, organic substances in brewery wastewater can be handled in a cost-effective and environmentally friendly manner using the gravel-filled trickling filter. PMID:24101209

Habte Lemji, Haimanot; Eckstädt, Hartmut

2013-10-01

30

Enhanced removal of chemical oxygen demand, nitrogen and phosphorus using the ameliorative anoxic/anaerobic/oxic process and micro-electrolysis.  

PubMed

Synthetic wastewater was treated using a novel system integrating the reversed anoxic/anaerobic/oxic (RAAO) process, a micro-electrolysis (ME) bed and complex biological media. The system showed superior chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) removal rates. Performance of the system was optimised by considering the influences of three major controlling factors, namely, hydraulic retention time (HRT), organic loading rate (OLR) and mixed liquor recirculation (MLR). TP removal efficiencies were 69, 87, 87 and 83% under the HRTs of 4, 8, 12 and 16 h. In contrast, HRT had negligible effects on the COD and TN removal efficiencies. COD, TN and TP removal efficiencies from synthetic wastewater were 95, 63 and 87%, respectively, at an OLR of 1.9 g/(L·d). The concentrations of COD, TN and TP in the effluent were less than 50, 15 and 1 mg/L, respectively, at the controlled MLR range of 75-100%. In this system, organics, TN and TP were primarily removed from anoxic tank regardless of the operational conditions. PMID:22766877

Bao, K Q; Gao, J Q; Wang, Z B; Zhang, R Q; Zhang, Z Y; Sugiura, N

2012-01-01

31

A pilot scale trickling filter with pebble gravel as media and its performance to remove chemical oxygen demand from synthetic brewery wastewater*  

PubMed Central

Evaluating the performance of a biotrickling filter for the treatment of wastewaters produced by a company manufacturing beer was the aim of this study. A pilot scale trickling filter filled with gravel was used as the experimental biofilter. Pilot scale plant experiments were made to evaluate the performance of the trickling filter aerobic and anaerobic biofilm systems for removal of chemical oxygen demand (COD) and nutrients from synthetic brewery wastewater. Performance evaluation data of the trickling filter were generated under different experimental conditions. The trickling filter had an average efficiency of (86.81±6.95)% as the hydraulic loading rate increased from 4.0 to 6.4 m3/(m2?d). Various COD concentrations were used to adjust organic loading rates from 1.5 to 4.5 kg COD/(m3?d). An average COD removal efficiency of (85.10±6.40)% was achieved in all wastewater concentrations at a hydraulic loading of 6.4 m3/(m2?d). The results lead to a design organic load of 1.5 kg COD/(m3?d) to reach an effluent COD in the range of 50–120 mg/L. As can be concluded from the results of this study, organic substances in brewery wastewater can be handled in a cost-effective and environmentally friendly manner using the gravel-filled trickling filter.

Habte Lemji, Haimanot; Eckstadt, Hartmut

2013-01-01

32

Huge supply/demand increases seen in oxygenate forecasts  

SciTech Connect

Industry originally projected that oxygenate supply would not be able to meet the demand created by U.S. oxygenated and reformulated gasoline mandates. This paper reports that those projections have been reserved in two recent industry reports - one from Chemical Market Associates Inc. (CMAI) and one from Pace Consultants Inc. Pace's report, by Paulo Nery and Nathan Sims, predicts gasoline and oxygenates demand, and examines the role ethanol may play in changing those values. CMAI's report estimates captive supply and demand of butylenes and oxygenates. Oxygenates are entering the domestic gasoline market this winter as a result of the 1990 U.S. Clean Air Act Amendments. Methyl tertiary butyl ether (MTBE) is the most important oxygenate, although ethanol, ethyl tertiary butyl ether (ETBE), and tertiary amyl methyl ether (TAME) are gathering market strength. Ethanol's strength is derived from President Bush's ruling granting a waiver to reformulated gasoline containing ethanol. This waiver allows ethanol blends to have a vapor pressure 1 psi higher than other types of gasoline.

Rhoades, A.K.

1992-11-30

33

Dissolved Organic In Natural and Polluted Waters: Methodology and Results of Running Control of Chemical Oxygen Demand (cod) For The Inland and Marine Aquatic System  

NASA Astrophysics Data System (ADS)

Current control of dissolved organic matter in natural and waste waters is the definition traditionally of chemical oxygen demand (COD) -- one of the basic parameters of quality of water. According to the International Standard (ISO 6060), it requires not less than one hour, while in many cases the operative information about amount of dissolved organic matter in aquatic environments have importance for prevention of an emergency. The standard method is applicable to waters with meaning of COD above 30 mg O2/l and, as the chloride ion prevents, it could be difficult for assessment of organic matter in sea water. Besides it is based on dichromate oxidation of the sum of organic substances in strong acid conditions at the presence of silver and mercury, that resulted in formation toxic pollutants. Till now attempts of automation of the COD definition in aquatic system were limited, basically, to duplication of the technology submitted the above standard (automatic COD analyzers "SERES Co."-- France, or "Tsvet Co." - Russia). The system of ozone-chemiluminescence automatic control of organic matter in water (CS COD) is offered and designed. Its based on the ozone oxidation of these substances in flowing water system and measurement arising from luminescent effects. CS COD works in real time. An instrument uses for reaction the atmospheric air, doesn't require fill of reagents and doesn't make new toxic pollutants. The system was tested in laboratory, and biochemical control of organic matter in water samples gathered from the river Neva and other polluted inland water areas and basins in St. Petersburg region was fulfilled (distilled water was used as "zero" media). The results of systematization of these measurements are presented. The new special ozone generator and flowing reactor for real-time running control of different waters in natural conditions were developed, and several series of large - scale field experiments onboard research ship were provided. Comprehensive study of the natural waters (including biohydro-chemical parameters control) for large part of the inland waterway St. Petersburg ­ White Sea (river Neva - Ladoga Lake ­ river Svir - Onega Lake ­ Petrozavodsk) was provided in frame the experimental voyage onboard the m/v «St. Peterburg» (J uly 1998 and June 1999). The results of organic matter charting for the different water masses for vast water basin in the northwestern of Russia were analyzed and classified. The arrangement of dissolved organic for the largest in Europe lakes Ladoga and Onega is analyzed in comparison with hydrological and meteorological processes and phenomena, including thermal regime modification. Spatial and temporal (seasonal and annual) transformation of organic matter for these water basins are studied. Aquatic environment conditions of the coastal zones, different bays and gulfs more pressed by livestock and agricultural farms, and industry are assessed also. According to the shipborne data more polluted water areas are the Svir Bay (Ladoga Lake) and Petrozavodskaya Guba (Onega Lake). These results are well correlated with in situ data and literature data. Thus, first time in practice is carried out the running control of a COD and spatial profile of the organic matter for different natural waters. Accuracy of measurements in comparison with traditional approaches and new technologies (including ideas and results practical application of sonoluminiscence of dissolved organic) are discussed also. The modification of CS COD was used for the cont rol of dissolved organic in different marine aquatic system. Sea water samples and preserved ice cores, gathered in the Barents, White and Kara Seas, were investigated. Probes of saltish and brackish-water (as ice cores) from the estuary of great Siberian rivers (Ob Bay and Yenisey Gulf) were analyzed in laboratory (biochemical analysis of these probes was fulfilled also). It was demonstrat ed that CS COD system can be used till range a salinity 25-33% ?, that opens to use this method for operative asse

Melentyev, K. V.; Worontsov, A. M.

34

Prediction of effluent biochemical oxygen demand in a dairy plant SBR wastewater system  

Microsoft Academic Search

The effluent from a Sequencing Batch Reactor (SBR) that was used to treat waste water from a fluid milk processing plant was utilized in this study. After analyzing the waste water for biochemical oxygen demand (BOD), chemical oxygen demand (COD), total solids (TS), total suspended solids (TSS) and pH, a prediction equation for BOD was calculated. This prediction equation can

R. H. Gough; P. J. Samkutty; P. McGrew; J. Arauz; R. W. Adkinson

2000-01-01

35

Sedimentary microbial oxygen demand for laminar flow over a sediment bed of finite length  

Microsoft Academic Search

Dead organic material accumulated on the bed of a lake, reservoir or wetland often provides the substrate for substantial microbial activity as well as chemical processes that withdraw dissolved oxygen (DO) from the water column. A model to estimate the actual DO profile and the “sedimentary oxygen demand (SOD)” must specify the rate of microbial or chemical activity in the

Makoto Higashino; Heinz G. Stefan

2005-01-01

36

Comparison of Methods to Determine Oxygen Demand for Bioremediation of a Fuel Contaminated Aquifer.  

National Technical Information Service (NTIS)

Four analytical methods were compared for estimating concentrations of fuel contaminants in subsurface core samples. The methods were total organic carbon, chemical oxygen demand, oil and grease, and a solvent extraction of fuel hydrocarbons combined with...

R. M. Powell R. W. Callaway J. T. Michalowski S. A. Vandegrift M. V. White

1988-01-01

37

COMPARISON OF METHODS TO DETERMINE OXYGEN DEMAND FOR BIOREMEDIATION OF A FUEL CONTAMINATED AQUIFER  

EPA Science Inventory

Four analytical methods were compared for estimating concentrations of fuel contaminants in subsurface core samples. The methods were total organic carbon, chemical oxygen demand, oil and grease, and a solvent extraction of fuel hydrocarbons combined with a gas chromatographic te...

38

COMPARISON OF METHODS TO DETERMINE OXYGEN DEMAND FOR BIOREMEDIATION OF A FUEL CONTAMINATED AQUIFER  

EPA Science Inventory

Four analytical methods were compared for estimating concentrations of fuel contaminants in subsurface core samples. he methods were total organic carbon, chemical oxygen demand, oil and grease, and a solvent extraction of fuel hydrocarbons combined with a gas chromatographic tec...

39

Potential Oxygen Demand of Sediments from Lake Erie  

Microsoft Academic Search

Dreissenid mussels (Dreissena polymorpha and D. bugensis) biodeposit large quantities of filtered materials (i.e., feces and pseudofeces) directly on bottom substrates. These biodeposits have the potential to increase oxygen demand in sediments and overlying waters and thus contribute to hypolimnetic anoxia in Lake Erie. We hypothesized that higher potential oxygen demand of sediments would occur in areas near shore than

Don W. Schloesser; Richard G. Stickel; Thomas B. Bridgeman

2005-01-01

40

Scalable chemical oxygen - iodine laser  

SciTech Connect

The problem of scaling chemical oxygen - iodine lasers (COILs) is discussed. The results of experimental study of a twisted-aerosol singlet oxygen generator meeting the COIL scalability requirements are presented. The energy characteristics of a supersonic COIL with singlet oxygen and iodine mixing in parallel flows are also experimentally studied. The output power of {approx}7.5 kW, corresponding to a specific power of 230 W cm{sup -2}, is achieved. The maximum chemical efficiency of the COIL is {approx}30%.

Adamenkov, A A; Bakshin, V V; Vyskubenko, B A; Efremov, V I; Il'in, S P; Ilyushin, Yurii N; Kolobyanin, Yu V; Kudryashov, E A; Troshkin, M V [Russian Federal Nuclear Center 'All-Russian Research Institute of Experimental Physics', Sarov, Nizhnii Novgorod region (Russian Federation)

2011-12-31

41

DIAGENETIC OXYGEN EQUIVALENTS MODEL OF SEDIMENT OXYGEN DEMAND  

EPA Science Inventory

The consumption of oxygen in the overlying water by sediments is an important component in the oxygen balance of most natural waters. Conventional practice is to specify the magnitude of this sink using direct uptake measurements. Unfortunately, if the management alternative bein...

42

Potential oxygen demand of sediments from Lake Erie  

USGS Publications Warehouse

Dreissenid mussels (Dreissena polymorpha and D. bugensis) biodeposit large quantities of filtered materials (i.e., feces and pseudofeces) directly on bottom substrates. These biodeposits have the potential to increase oxygen demand in sediments and overlying waters and thus contribute to hypolimnetic anoxia in Lake Erie. We hypothesized that higher potential oxygen demand of sediments would occur in areas near shore than in offshore hypolimnetic waters as a result of biodeposits carried by currents from littoral water where mussels, available foods, and biodeposits may be most abundant. To address this hypothesis, we measured potential oxygen demand (mg O2/L/120 h incubation) at six sites near shore and six sites offshore monthly June to September 2002 and August 2003. In addition, we compared, in post priori hypothesis, seven sites with and five sites without dreissenid mussels. Contrary to our hypotheses, potential oxygen demand was not significantly higher in bottles containing nearshore sediments than offshore sediments. Similarly, potential oxygen demand was not significantly higher at sites with dreissenid mussels than at sites without mussels. Data are consistent with pre-dreissenid studies which show oxygen demand and percent ash-free dry weights of sediments were higher offshore than near shore and ash-free dry weight of sediments decreased June to September. Therefore, the present study provides no evidence that dreissenid mussels have contributed directly-via biodeposition-to increased anoxia observed in Lake Erie in the mid to late 1990s.

Schloesser, D. W.; Stickel, R. G.; Bridgeman, T. B.

2005-01-01

43

Biological oxygen demand (BOD) monitoring by a multiprocessing system  

Microsoft Academic Search

The describes the development of a prototype device in which parallel computer control techniques are used for the rapid on-line measurement of the biological oxygen demand (BOD). Wastewater samples diluted with fresh water are fed into a whirl bed reactor in which microorganisms are grown. A computer-based feedback controller keeps the oxygen consumed in the reactor to a constant value

George Hassapis

1991-01-01

44

A solid composite electrode for the determination of the electrochemical oxygen demand of aqueous samples  

Microsoft Academic Search

A composite electrode containing graphite, paraffin, AgO and CuO is described for the determination of the electrochemical\\u000a oxygen demand (EOD) of waste waters. The oxidation of dissolved organic compounds at the electrode is based on a heterogeneous\\u000a chemical reaction of AgO\\/CuO with the organic constituents of the waste water. This chemical reaction can be followed by a\\u000a solid state electrochemical

R. Rössler-Fromme; F. Scholz

1996-01-01

45

Effects of dilution on dissolved oxygen depletion and microbial populations in the biochemical oxygen demand determination  

Microsoft Academic Search

The biochemical oxygen demand (BOD) value is still a key parameter that can determine the level of organics, particularly\\u000a the content of biodegradable organics in water. In this work, the effects of sample dilution, which should be done inevitably\\u000a to get appropriate dissolved oxygen (DO) depletion, on the measurement of 5-day BOD (BOD5), was investigated with and without seeding using

Kyo Seong Seo; Ho Nam Chang; Joong Kon Park; Kwang-Ho Choo

2007-01-01

46

Watershed modeling of dissolved oxygen and biochemical oxygen demand using a hydrological simulation Fortran program  

Microsoft Academic Search

Several inland water bodies in the St. Louis Bay watershed have been identified as being potentially impaired due to low level of dissolved oxygen (DO). In order to calculate the total maximum daily loads (TMDL), a standard watershed model supported by U.S. Environmental Protection Agency, Hydrological Simulation Program Fortran (HSPF), was used to simulate water temperature, DO, and bio-chemical oxygen

Zhijun Liu; Janna M. Kieffer; William L. Kingery; David H. Huddleston; Faisal Hossain

2007-01-01

47

The effect of mayfly ( Hexagenia spp.) burrowing activity on sediment oxygen demand in western Lake Erie  

Microsoft Academic Search

Previous studies support the hypothesis that large numbers of infaunal burrow-irrigating organisms in the western basin of Lake Erie may increase significantly the sediment oxygen demand, thus enhancing the rate of hypolimnetic oxygen depletion. We conducted laboratory experiments to quantify burrow oxygen dynamics and increased oxygen demand resulting from burrow irrigation using two different year classes of Hexagenia spp. nymphs

William J. Edwards; Frederick M. Soster; Gerald Matisoff; Donald W. Schloesser

2009-01-01

48

Micro Chemical Oxygen-Iodine Laser (COIL).  

National Technical Information Service (NTIS)

It has been previously proposed to improve the performance and compactness of chemical oxygen-iodine lasers (COIL) through the replacement of some of their macroscale components with arrays of higher-performing microscale (MEMS) components. In this progra...

C. Livermore-Clifford

2007-01-01

49

Temperature, Dissolved Oxygen, Total Alkalinity, and Biochemical Oxygen Demand in the Columbia River Estuary, 1966-67.  

National Technical Information Service (NTIS)

Temperature, dissolved oxygen, total alkalinity, and biochemical oxygen demand collected at 19 locations in the Columbia River estuary are presented as a reference for researchers in fisheries or in water quality. (Author)

C. W. Sims C. J. Cederholm

1970-01-01

50

Chemicals On Demand with Phototriggerable Microcapsules  

PubMed Central

We report the development of phototriggerable microcapsules, and demonstrate the concept of protection- and remote release of chemical species. Light-rupturable, liquid-filled microcapsules were prepared by co-encapsulation of carbon nanotubes using a simple and robust interfacial polymerization technique. The incorporation of carbon nanotubes endows the microcapsules with the ability to respond to an external optical event. The triggered release of the liquid contents for the microcapsules may be achieved either in air or within a liquid medium via irradiation with a near-IR laser. Rupture of the impermeable shell-wall under irradiation is presumed to be due to an increase in internal pressure due to optothermal heating of the CNTs. The storage and triggered release of reactive small molecules and catalysts was demonstrated in the context of remotely initiated “click” reaction and ring-opening metathesis polymerization.

Pastine, Stefan J.; Okawa, David; Zettl, Alex; Frechet, Jean M. J.

2009-01-01

51

Petroleum industry effluents and other oxygen-demanding wastes in Niger Delta, Nigeria.  

PubMed

In this article, we review the fundamental phenomenon of oxygenation within the overriding context of petroleum-industry effluents and the other oxygen demanding wastes in Niger Delta, Nigeria. Drill cuttings, drilling mud (fluids used to stimulate the production processes), and accidental discharges of crude petroleum constitute serious land and water pollution in the oil-bearing province. Effluents from other industrial establishments such as distilleries, pulp and paper mills, fertilizer plants, and breweries, as well as thermal effluents, plant nutrients (such as nitrates and phosphates), and eroded sediments have also contributed to the pollution of their surrounding environment. Since these wastes are oxygen-demanding in nature, their impact on the recipient environment can be reversed by the direct application of simple chemistry. The wastes can be reduced, particularly in natural bodies of water, by direct oxidation-reduction processes or simple chemical combinations, acid-base reactions, and solubility equilibria; these are pH- and temperature-dependent. A shift in pH and alkalinity affects the solubility equilibria of Na+, Cl-, SO(2-), NO3(-), HCO3(-), and PO4(3-), and other ions and compounds. PMID:17193303

Osuji, Leo C; Uwakwe, Augustine A

2006-07-01

52

Desk Top Methodology for Modeling Biochemical Oxygen Demand in Streams.  

National Technical Information Service (NTIS)

The modeling of dissolved oxygen as widely practiced involves considerable uncertainties due partly to the assumptions not fully represented by the model and also, usually great deficiencies in data. The diurnal fluctuation of oxygen complicates the water...

W. Whipple J. V. Hunter

1980-01-01

53

Addressing the design of chemical supply chains under demand uncertainty  

Microsoft Academic Search

This work addresses the design of chemical supply chains (SCs) with multi-product, multi-echelon distribution networks under demand uncertainty. Given a design horizon consisting of several time periods in which product demands materialize, the objective is to select the design that maximizes the expected profit. To tackle this problem, it is derived a multi-stage stochastic formulation wherein the design decisions are

Gonzalo Guillén; Fernando D. Mele; Antonio Espuña; Luis Puigjaner

2006-01-01

54

The use of iron oxide as oxygen carrier in a chemical-looping reactor  

Microsoft Academic Search

Chemical-looping combustion (CLC) is a method for the combustion of fuel gas with inherent separation of carbon dioxide. This technique involves the use of two interconnected reactors, an air reactor and a fuel reactor. The oxygen demanded in the fuel combustion is supplied by a solid oxygen carrier, which circulates between both reactors. Fuel gas and air are never mixed

A. Abad; T. Mattisson; A. Lyngfelt; M. Johansson

2007-01-01

55

A comparison between the multiple linear regression model and neural networks for biochemical oxygen demand estimations  

Microsoft Academic Search

The most common test for determining the strength of organic content in wastewaters is the biochemical oxygen demand (BOD). The variables of water quality are temperature, pH value (pH), dissolved oxygen (DO), substance solid (SS), total Kjeldahl nitrogen (TKN), ammonia nitrogen (NH3N), nitrate (NO3), total phosphorous(T-P), and total coliform bacteria (T-coliform). These water quality indices affect biochemical oxygen demand. The

S. Areerachakul; S. Sanguansintukul

2009-01-01

56

Myocardial oxygen supply:demand ratio as reference for coronary vasodilatory drug effects in humans  

Microsoft Academic Search

OBJECTIVE: Introduction and measurement of human myocardial oxygen supply:demand ratio as a reference for quantification of coronary microvascular vasodilating drug effects in clinical studies. Myocardial oxygen consumption is the major determinant of coronary blood flow; therefore, the true vasodilating properties of coronary vasodilating drugs that may have an effect on oxygen consumption cannot be correctly assessed from blood flow changes

I. Vergroesen; J. E. Kal; J. A. E. Spaan; H. B. Van Wezel

1997-01-01

57

Supersonic cw chemical oxygen-iodine laser  

Microsoft Academic Search

Summary form only given. Supersonic continuous wave (cw) chemical oxygen-iodine lasers (COIL) have been studied for many years. By using the rotating disk O\\/sub 2\\/ generator and using supersonic gas flow instead of subsonic gas flow in the laser cavity, the laser output power has been improved. We got 5-kW laser output power with Cl flow rate at 0.3 moles\\/second.

Li Bin; Cheng Fang; Sang Feng Ting; Zhou Da Zheng; Zhuang Qi; Yang Bo Ling

1996-01-01

58

Oxygen Concentration and Demand in Lake Erie Sediments  

Microsoft Academic Search

Regular ship-board monitoring of oxygen in the hypolimnion of Lake Erie has been established to monitor the status of the lake and determine if the water quality is meeting the terms of the Great Lakes Water Quality Agreement (GLWQA). However, lake-wide monitoring is expensive and there is a difference of opinion on whether dissolved oxygen depletion rate is a good

Gerald Matisoff; Thomas M. Neeson

2005-01-01

59

Phillips Laboratory COIL technology overview. [Chemical oxygen-iodine laser  

Microsoft Academic Search

The basic technology and performance of the chemically dumped oxygen-iodine laser is reviewed. The performance is discussed in terms of the operation of the chemical oxygen generator, the kinetics of energy transfer from oxygen to iodine, and the extraction of power by the optical resonator. Techniques for generation of excited oxygen and iodine are reviewed. In addition advanced concepts for

K. A. Truesdell; S. E. Lamberson; G. D. Hager

1992-01-01

60

14 CFR 23.1450 - Chemical oxygen generators.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Chemical oxygen generators. 23.1450 Section 23...Miscellaneous Equipment § 23.1450 Chemical oxygen generators. (a) For the purpose of this section, a chemical oxygen generator is defined as a device...

2013-01-01

61

14 CFR 25.1450 - Chemical oxygen generators.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Chemical oxygen generators. 25.1450 Section 25...Miscellaneous Equipment § 25.1450 Chemical oxygen generators. (a) For the purpose of this section, a chemical oxygen generator is defined as a device...

2013-01-01

62

Myocardial oxygen supply:demand ratio as reference for coronary vasodilatory drug effects in humans.  

PubMed Central

OBJECTIVE: Introduction and measurement of human myocardial oxygen supply:demand ratio as a reference for quantification of coronary microvascular vasodilating drug effects in clinical studies. Myocardial oxygen consumption is the major determinant of coronary blood flow; therefore, the true vasodilating properties of coronary vasodilating drugs that may have an effect on oxygen consumption cannot be correctly assessed from blood flow changes alone. DESIGN: Prospective, controlled trial. SETTING: Academic hospital. PATIENTS: 12 patients with multivessel coronary artery disease (CAD) undergoing coronary artery bypass grafting. INTERVENTIONS: Cardiac pacing at 30 beats/min above sinus rhythm in awake and anaesthetised patients (fentanyl/pancuronium bromide). MAIN OUTCOME MEASURES: Myocardial oxygen supply, defined as coronary sinus blood flow multiplied by arterial oxygen content; myocardial oxygen demand, defined as coronary sinus blood flow multiplied by arteriovenous oxygen content difference. The change in oxygen demand induced by pacing was related to the change in myocardial oxygen supply in awake and anaesthetised patients. This myocardial oxygen supply:demand ratio determined in the reference study was compared with that induced by intravenous and intracoronary drugs (nifedipine, felodipine, urapidil, and sodium nitroprusside) in two pharmacological studies: patients with CAD undergoing cardiac surgery (45 treated with sodium nitroprusside, 27 with nifedipine, and 27 with urapidil to manage arterial blood pressure); and patients with unstable angina (and a similar degree of CAD) undergoing cardiac catheterisation for diagnostic purposes (10 treated with intracoronary nifedipine and 10 with intracoronary felodipine). RESULTS: When awake, the ratio of pacing induced oxygen supply:demand changes in the 12 reference study patients was 1.50 (95% confidence intervals (CI), 1.41-1.58), similar to the 1.45 (1.35-1.56) measured in the same patients after induction of anaesthesia. Anaesthesia per se did not increase coronary oxygen supply above the expected increase related to demand changes. The only significant change in the oxygen supply:demand ratio was induced by intracoronary bolus administration of nifedipine and felodipine (10.6 (SE 1.9) and 13.9 (1.9) ml/min, respectively, above the demand related supply). CONCLUSIONS: Quantification of coronary vasoactive properties in relation to the physiological reference ratio between myocardial oxygen supply and demand may be a powerful tool to differentiate between true and apparent coronary vasoactive drugs. Images

Vergroesen, I.; Kal, J. E.; Spaan, J. A.; Van Wezel, H. B.

1997-01-01

63

MODELING SEDIMENT-NUTRIENT FLUX AND SEDIMENT OXYGEN DEMAND  

EPA Science Inventory

Depositional flux of particulate organic matter in bottom sediments affects nutrients cycling at the sediment-water interface and consumes oxygen from the overlying water in streams, lakes, and estuaries. This project deals with analytical modeling of nitrogen and carbon producti...

64

Chemical kinetics of discharge-driven oxygen-iodine lasers  

Microsoft Academic Search

Oxygen-iodine lasers that utilize electrical discharges to produce O2(a1Delta) are currently being developed. The discharge generators differ from those used in chemical oxygen-iodine lasers in that they produce significant amounts of atomic oxygen and traces of ozone. As a consequence of these differences, the chemical kinetics of the discharge laser are markedly different from those of a conventional chemical oxygen-iodine

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

2007-01-01

65

Rapid estimation of biochemical oxygen demand using a microbial multi-staged bioreactor  

Microsoft Academic Search

A multi-staged bioreactor system consisting of Trichosporon cutaneum immobilized in Ca-alginate bead and nylon columns was prepared for the estimation of biochemical oxygen demand (BOD) of waste waters. When a sample solution containing the equivalent amount of glucose and glutamic acid (GGA) was injected into the reactor system, the dissolved oxygen (DO) in the sample was decreased with the concentration

Moo-Jeong Sohn; Jang-Wook Lee; Chinkap Chung; Gwon-Shik Ihn; Daeil Hong

1995-01-01

66

Determination of Biochemical Oxygen Demand of Area Waters: A Bioassay Procedure for Environmental Monitoring  

ERIC Educational Resources Information Center

|A graphical method for determining the 5-day biochemical oxygen demand (BOD5) for a body of water is described. In this bioassay, students collect a sample of water from a designated site, transport it to the laboratory, and evaluate the amount of oxygen consumed by naturally occurring bacteria during a 5-day incubation period. An accuracy check,…

Riehl, Matthew

2012-01-01

67

The effect of mayfly (Hexagenia spp.) burrowing activity on sediment oxygen demand in western Lake Erie  

USGS Publications Warehouse

Previous studies support the hypothesis that large numbers of infaunal burrow-irrigating organisms in the western basin of Lake Erie may increase significantly the sediment oxygen demand, thus enhancing the rate of hypolimnetic oxygen depletion. We conducted laboratory experiments to quantify burrow oxygen dynamics and increased oxygen demand resulting from burrow irrigation using two different year classes of Hexagenia spp. nymphs from western Lake Erie during summer, 2006. Using oxygen microelectrodes and hot film anemometry, we simultaneously determined oxygen concentrations and burrow water flow velocities. Burrow oxygen depletion rates ranged from 21.7 mg/nymph/mo for 15 mm nymphs at 23 °C to 240.7 mg/nymph/mo for 23 mm nymphs at 13 °C. Sealed microcosm experiments demonstrated that mayflies increase the rate of oxygen depletion by 2-5 times that of controls, depending on size of nymph and water temperature, with colder waters having greater impact. At natural population densities, nymph pumping activity increased total sediment oxygen demand 0.3-2.5 times compared to sediments with no mayflies and accounted for 22-71% of the total sediment oxygen demand. Extrapolating laboratory results to the natural system suggest that Hexagenia spp. populations may exert a significant control on oxygen depletion during intermittent stratification. This finding may help explain some of the fluctuations in Hexagenia spp. population densities in western Lake Erie and suggests that mayflies, by causing their own population collapse irrespective of other environmental conditions, may need longer term averages when used as a bio-indicator of the success of pollution-abatement programs in western Lake Erie and possibly throughout the Great Lakes.

Edwards, William J.; Soster, Frederick M.; Matisoff, Gerald; Schloesser, Donald W.

2009-01-01

68

In situ global method for measurement of oxygen demand and mass transfer  

SciTech Connect

Two aerobic microorganisms, Saccharomycopsis lipolytica and Brevibacterium lactofermentum, have been used in a study of mass transfer and oxygen uptake from a global perspective using a closed gas system. Oxygen concentrations in the gas and liquid were followed using oxygen electrodes, and the results allowed for easy calculation of in situ oxygen transport. The cell yields on oxygen for S. lipolytica and B. lactofermentum were 1.01 and 1.53 g/g respectively. The mass transfer coefficient was estimated as 10 h{sup {minus}1} at 500 rpm for both fermentations. The advantages with this method are noticeable since the use of model systems may be avoided, and the in situ measurements of oxygen demand assure reliable data for scale-up.

Klasson, K.T. [Oak Ridge National Lab., TN (United States). Chemical Technology Div.; Lundbaeck, K.M.O.; Clausen, E.C.; Gaddy, J.L. [Univ. of Arkansas, Fayetteville, AR (United States). Dept. of Chemical Engineering

1997-05-01

69

Oxygen demand and sulfate reduction in petroleum hydrocarbon contaminated salt marsh soils  

Microsoft Academic Search

Laboratory studies were conducted using salt marsh cores to determine the oxygen demand exerted by spilled crude oil and fertilizers added to stimulate biodegradation. Measurements of oxygen uptake and CO2 efflux in flooded and non-flooded cores were conducted in addition to measurements of the magnitude and depth distribution of sulfate reduction rates using 35SO2?4. Additions of crude oil and fertilizers

Won Sik Shin; John H. Pardue; W. Andrew Jackson

2000-01-01

70

A Novel Microbial Sensor Immobilized Arxula adeninivorans for Biochemical Oxygen Demand Measure in High Salt Condition  

Microsoft Academic Search

A microbial sensor, based on an immobilized mixed the yeast Arxula adeninivorans with a Clark-type oxygen electrode, has been developed for the measurement of Biochemical Oxygen Demand(BOD) in high salt wastewater. Arxula is immobilized in the Polyvinyl Alcohol (PVA). Arxula is salt tolerant, it can give a stable signal up to 100g\\/L NaCl in sample. The influence of pH, temperature

Hu Lei; Li Yi

2010-01-01

71

14 CFR 25.1450 - Chemical oxygen generators.  

Code of Federal Regulations, 2010 CFR

...each portable chemical oxygen generator that is capable...replacement of a generator element must be placarded to showâ (1) The rate of oxygen flow, in liters per...2) The duration of oxygen flow, in minutes, for the replaceable generator element; and (3) A...

2009-01-01

72

14 CFR 23.1450 - Chemical oxygen generators.  

Code of Federal Regulations, 2010 CFR

...each portable chemical oxygen generator that is capable...replacement of a generator element must be placarded to showâ (1) The rate of oxygen flow, in liters per...2) The duration of oxygen flow, in minutes, for the replaceable generator element; and (3) A...

2009-01-01

73

14 CFR 25.1450 - Chemical oxygen generators.  

Code of Federal Regulations, 2010 CFR

...each portable chemical oxygen generator that is capable...replacement of a generator element must be placarded to showâ (1) The rate of oxygen flow, in liters per...2) The duration of oxygen flow, in minutes, for the replaceable generator element; and (3) A...

2010-01-01

74

14 CFR 23.1450 - Chemical oxygen generators.  

Code of Federal Regulations, 2010 CFR

...each portable chemical oxygen generator that is capable...replacement of a generator element must be placarded to showâ (1) The rate of oxygen flow, in liters per...2) The duration of oxygen flow, in minutes, for the replaceable generator element; and (3) A...

2010-01-01

75

A reagent-free tubular biofilm reactor for on-line determination of biochemical oxygen demand.  

PubMed

We reported a reagent-free tubular biofilm reactor (BFR) based analytical system for rapid online biochemical oxygen demand (BOD) determination. The BFR was cultivated using microbial seeds from activated sludge. It only needs tap water to operate and does not require any chemical reagent. The analytical performance of this reagent-free BFR system was found to be equal to or better than the BFR system operated using phosphate buffer saline (PBS) and high purity deionized water. The system can readily achieve a limit of detection of 0.25 mg O2 L(-1), possessing superior reproducibility, and long-term operational and storage stability. More importantly, we confirmed for the first time that the BFR system is capable of tolerating common toxicants found in wastewaters, such as 3,5-dichlorophenol and Zn(II), Cr(VI), Cd(II), Cu(II), Pb(II), Mn(II) and Ni(II), enabling the method to be applied to a wide range of wastewaters. The sloughing and clogging are the important attributes affecting the operational stability, hence, the reliability of most online wastewater monitoring systems, which can be effectively avoided, benefiting from the tubular geometry of the reactor and high flow rate conditions. These advantages, coupled with simplicity in device, convenience in operation and minimal maintenance, make such a reagent-free BFR analytical system promising for practical BOD online determination. PMID:23500366

Liu, Changyu; Zhao, Huijun; Gao, Shan; Jia, Jianbo; Zhao, Limin; Yong, Daming; Dong, Shaojun

2013-02-09

76

Simulating unsteady transport of nitrogen, biochemical oxygen demand, and dissolved oxygen in the Chattahoochee River downstream from Atlanta, Georgia  

USGS Publications Warehouse

As part of an intensive water-quality assessment of the Chattahoochee River, repetitive water-quality measurements were made at 12 sites along a 69-kilometer reach of the river downstream of Atlanta, Georgia. Concentrations of seven constituents (temperature, dissolved oxygen, ultimate carbonaceous biochemical oxygen demand (BOD), organic nitrogen, ammonia, nitrite, and nitrate) were obtained during two periods of 36 hours, one starting on August 30, 1976, and the other starting on May 31, 1977. The study reach contains one large and several small sewage outfalls and receives the cooling water from two large powerplants. An unsteady water-quality model of the Lagrangian type was calibrated using the 1977 data and verified using the 1976 data. The model provided a good means of interpreting these data even though both the flow and the pollution loading rates were highly unsteady. A kinetic model of the cascade type accurately described the physical and biochemical processes occurring in the river. All rate coefficients, except reaeration coefficients and those describing the resuspension of BOD, were fitted to the 1977 data and verified using the 1976 data. The study showed that, at steady low flow, about 38 percent of the BOD settled without exerting an oxygen demand. At high flow, this settled BOD was resuspended and exerted an immediate oxygen demand. About 70 percent of the ammonia extracted from the water column was converted to nitrite, but the fate of the remaining 30 percent is unknown. Photosynthetic production was not an important factor in the oxygen balance during either run.

Jobson, Harvey E.

1985-01-01

77

Experimental Study of Supersonic Chemical Oxygen-Iodine Laser (COIL).  

National Technical Information Service (NTIS)

A 5kW supersonic chemical oxygen-iodine laser (COIL) was constructed. A rotating mesh-type singlet-delta oxygen generator (SOG) was used that appears to be simpler, lighter in weight, and more efficient than the rotating disk SOG. An output power of 1kw f...

S. Fengting C. Fang Y. Bailing S. Yizhu J. Yuqi

1996-01-01

78

The control of ventilatory and cardiac responses to changes in ambient oxygen tension and oxygen demand in octopus  

PubMed

Octopus vulgaris can regulate its oxygen uptake down to a PO2 of around 6.7 kPa. As the tension falls from 18.6 to 6.7 kPa (140 to 50 mmHg), Pv (the pressure pulse driving the ventilatory flow, measured inside the mantle cavity) can more than double while fv (the ventilation frequency) increases by a few per cent at most. Both changes are reversed when the ambient oxygen tension is returned to normal. Cutting the visceral nerves linking the hearts and gills to the brain prevents these adaptive changes in Pv and fv, as does section of the branchial nerves linking the cardiac ganglia to the gills. Responses to changes in ambient oxygen tension are very fast, beginning within two or three ventilation cycles. It is concluded that changes to Pv and fv depend upon receptors in the gills and on the integrity of a nervous pathway to the brain. Changes in oxygen tension also affect the hearts, where aortic pulse amplitude (Pa) and, to a lesser extent, heartbeat frequency (fh) fall and rise with the ambient PO2. In this case, section of the visceral or branchial nerves has no effect. Responses are again very rapid. It is concluded that the observed fall and return to normoxic values of Pa and fh are local responses to a fall and rise in the oxygen tension of blood coming from the gills into the systemic heart. Changes to ventilation and heartbeat can also occur in normoxic water when oxygen demand rises after feeding. These responses are not prevented by section of the visceral or branchial nerves. Possible control of ventilation and heartbeat through the neurosecretory system in the anterior vena cava is discussed. PMID:9319626

Wells; Wells

1995-01-01

79

Continuous determination of biochemical oxygen demand using microbial fuel cell type biosensor  

Microsoft Academic Search

A mediator-less microbial fuel cell (MFC) was used as a biochemical oxygen demand (BOD) sensor in an amperometric mode for real-time wastewater monitoring. At a hydraulic retention time of 1.05h, BOD values of up to 100mg\\/l were measured based on a linear relationship, while higher BOD values were measured using a lower feeding rate. About 60min was required to reach

In Seop Chang; Jae Kyung Jang; Geun Cheol Gil; Mia Kim; Hyung Joo Kima; Byung Won Chob; Byung Hong Kima

2004-01-01

80

Transformations of nitrogen in a polluted estuary: nonlinearities in the demand for oxygen at low flow.  

PubMed

Oxidation of sewage ammonium in the Potomac River is described in terms of a simple kinetic model, with growth of nitrifying bacteria limited by the supply of ammonium ion. The oxidation rate varies inversely with freshwater inflow, and the associated demand for oxygen varies as the inverse square of the freshwater inflow rate. Similar behavior is observed for the Delaware River. The model accounts for the observed concentrations of ammonium and nitrous oxide. PMID:17834581

Wofsy, S C; McElroy, M B; Elkins, J W

1981-08-14

81

Oxygen demand during mineralization of aquatic macrophytes from an oxbow lake.  

PubMed

This study presents a kinetic model of oxygen consumption during aerobic decomposition of detritus from seven species of aquatic macrophytes: Cabomba furcata, Cyperus giganteus, Egeria najas, Eichhornia azurea, Salvinia auriculata, Oxycaryum cubense and Utricularia breviscapa. The aquatic macrophytes were collected from Oleo Lagoon situated in the Mogi-Guaçu river floodplain (SP, Brazil). Mineralization experiments were performed using the closed bottles method. Incubations made with lake water and macrophytes detritus (500 mL and 200 mg.L(-1) (DM), respectively) were maintained during 45 to 80 days at 20 degrees C under aerobic conditions and darkness. Carbon content of leachates from aquatic macrophytes detritus and dissolved oxygen concentrations were analyzed. From the results we concluded that: i) the decomposition constants differ among macrophytes; these differences being dependent primarily on molecular and elemental composition of detritus and ii) in the short term, most of the oxygen demand seems to depend upon the demineralization of the dissolved carbon fraction. PMID:18470379

Bianchini Jr, I; Cunha-Santino, M B; Peret, A M

2008-02-01

82

Measuring the Yield of Singlet Oxygen in a Chemical Oxygen Iodine Laser (Postprint).  

National Technical Information Service (NTIS)

A critical parameter for understanding the performance of Chemical Oxygen Iodine Lasers is the yield of singlet oxygen produced by the generator. Off-Axis Integrated Cavity Output Spectroscopy (Off-Axis ICOS) has been utilized to measure the absolute dens...

J. E. McCord K. B. Hewett M. Gupta T. Owano

2006-01-01

83

Simulation of Temperature, Nutrients, Biochemical Oxygen Demand, and Dissolved Oxygen in the Catawba River, South Carolina, 1996-97  

USGS Publications Warehouse

Time-series plots of dissolved-oxygen concentrations were determined for various simulated hydrologic and point-source loading conditions along a free-flowing section of the Catawba River from Lake Wylie Dam to the headwaters of Fishing Creek Reservoir in South Carolina. The U.S. Geological Survey one-dimensional dynamic-flow model, BRANCH, was used to simulate hydrodynamic data for the Branched Lagrangian Transport Model. Waterquality data were used to calibrate the Branched Lagrangian Transport Model and included concentrations of nutrients, chlorophyll a, and biochemical oxygen demand in water samples collected during two synoptic sampling surveys at 10 sites along the main stem of the Catawba River and at 3 tributaries; and continuous water temperature and dissolved-oxygen concentrations measured at 5 locations along the main stem of the Catawba River. A sensitivity analysis of the simulated dissolved-oxygen concentrations to model coefficients and data inputs indicated that the simulated dissolved-oxygen concentrations were most sensitive to watertemperature boundary data due to the effect of temperature on reaction kinetics and the solubility of dissolved oxygen. Of the model coefficients, the simulated dissolved-oxygen concentration was most sensitive to the biological oxidation rate of nitrite to nitrate. To demonstrate the utility of the Branched Lagrangian Transport Model for the Catawba River, the model was used to simulate several water-quality scenarios to evaluate the effect on the 24-hour mean dissolved-oxygen concentrations at selected sites for August 24, 1996, as simulated during the model calibration period of August 23 27, 1996. The first scenario included three loading conditions of the major effluent discharges along the main stem of the Catawba River (1) current load (as sampled in August 1996); (2) no load (all point-source loads were removed from the main stem of the Catawba River; loads from the main tributaries were not removed); and (3) fully loaded (in accordance with South Carolina Department of Health and Environmental Control National Discharge Elimination System permits). Results indicate that the 24-hour mean and minimum dissolved-oxygen concentrations for August 24, 1996, changed from the no-load condition within a range of - 0.33 to 0.02 milligram per liter and - 0.48 to 0.00 milligram per liter, respectively. Fully permitted loading conditions changed the 24-hour mean and minimum dissolved-oxygen concentrations from - 0.88 to 0.04 milligram per liter and - 1.04 to 0.00 milligram per liter, respectively. A second scenario included the addition of a point-source discharge of 25 million gallons per day to the August 1996 calibration conditions. The discharge was added at S.C. Highway 5 or at a location near Culp Island (about 4 miles downstream from S.C. Highway 5) and had no significant effect on the daily mean and minimum dissolved-oxygen concentration. A third scenario evaluated the phosphorus loading into Fishing Creek Reservoir; four loading conditions of phosphorus into Catawba River were simulated. The four conditions included fully permitted and actual loading conditions, removal of all point sources from the Catawba River, and removal of all point and nonpoint sources from Sugar Creek. Removing the point-source inputs on the Catawba River and the point and nonpoint sources in Sugar Creek reduced the organic phosphorus and orthophosphate loadings to Fishing Creek Reservoir by 78 and 85 percent, respectively.

Feaster, Toby D.; Conrads, Paul A.; Guimaraes, Wladmir B.; Sanders, Curtis L., Jr.; Bales, Jerad D.

2003-01-01

84

Light-responsive polymer nanoreactors: a source of reactive oxygen species on demand.  

PubMed

Various domains present the challenges of responding to stimuli in a specific manner, with the desired sensitivity or functionality, and only when required. Stimuli-responsive systems that are appropriately designed can effectively meet these challenges. Here, we introduce nanoreactors that encapsulate photosensitizer-protein conjugates in polymer vesicles as a source of "on demand" reactive oxygen species. Vesicles made of poly(2-methyloxazoline)-poly(dimethylsiloxane)-poly(2-methyloxazoline) successfully encapsulated the photosensitizer Rose Bengal-bovine serum albumin conjugate (RB-BSA) during a self-assembly process, as demonstrated by UV-Vis spectroscopy. A combination of light scattering and transmission electron microscopy indicated that the nanoreactors are stable over time. They serve a dual role: protecting the photosensitizer in the inner cavity and producing in situ reactive oxygen species (ROS) upon irradiation with appropriate electromagnetic radiation. Illumination with appropriate wavelength light allows us to switch on/off and to control the production of ROS. Because of the oxygen-permeable nature of the polymer membrane of vesicles, ROS escape into the environment around vesicles, as established by electron paramagnetic resonance. The light-sensitive nanoreactor is taken up by HeLa cells in a Trojan horse fashion: it is nontoxic and, when irradiated with the appropriate laser light, produces ROS that induce cell death in a precise area corresponding to the irradiation zone. These nanoreactors can be used in theranostic approaches because they can be detected via the fluorescent photosensitizer signal and simultaneously produce ROS efficiently "on demand". PMID:23154601

Baumann, Patric; Balasubramanian, Vimalkumar; Onaca-Fischer, Ozana; Sienkiewicz, Andrzej; Palivan, Cornelia G

2012-11-15

85

Development and characterization of a novel immobilized microbial membrane for rapid determination of biochemical oxygen demand load in industrial waste-waters  

Microsoft Academic Search

The rapid determination of waste-water quality of waste-water treatment plants in terms of pollutional strength, i.e. biochemical oxygen demand (BOD) is difficult or even impossible using the chemical determination method. The present study reports the determination of BOD within minutes using microbial BOD sensors, as compared to the 5-day determination using the conventional method. Multiple criteria establish the basis for

Shikha Rastogi; Anil Kumar; N. K Mehra; S. D Makhijani; A Manoharan; V Gangal; Rita Kumar

2003-01-01

86

Regulation of growth hormone during exercise by oxygen demand and availability  

Microsoft Academic Search

Summary  Five normal men performed seven sets of seven squats at a load equal to 80% of their seven repetition maximum. Plasma growth\\u000a hormone (GH) and lactate levels increased during and after the completion of the exercise. A significant (r=0.93, P<0.001) linear correlation was found between GH changes and the corresponding oxygen Demand\\/Availability (D\\/A) ratio expressed\\u000a by \\u000a $$\\\\left[ {\\\\int\\\\limits_0^x {\\\\dot V_{O_2

W. P. VanHelder; K. Casey; M. W. Radomski

1987-01-01

87

Development of a biochemical oxygen demand sensor using gold-modified boron doped diamond electrodes.  

PubMed

Gold-modified boron doped diamond (BDD) electrodes were examined for the amperometric detection of oxygen as well as a detector for measuring biochemical oxygen demand (BOD) using Rhodotorula mucilaginosa UICC Y-181. An optimum potential of -0.5 V (vs Ag/AgCl) was applied, and the optimum waiting time was observed to be 20 min. A linear calibration curve for oxygen reduction was achieved with a sensitivity of 1.4 ?A mg(-1) L oxygen. Furthermore, a linear calibration curve in the glucose concentration range of 0.1-0.5 mM (equivalent to 10-50 mg L(-1) BOD) was obtained with an estimated detection limit of 4 mg L(-1) BOD. Excellent reproducibility of the BOD sensor was shown with an RSD of 0.9%. Moreover, the BOD sensor showed good tolerance against the presence of copper ions up to a maximum concentration of 0.80 ?M (equivalent to 50 ppb). The sensor was applied to BOD measurements of the water from a lake at the University of Indonesia in Jakarta, Indonesia, with results comparable to those made using a standard method for BOD measurement. PMID:23088708

Ivandini, Tribidasari A; Saepudin, Endang; Wardah, Habibah; Harmesa; Dewangga, Netra; Einaga, Yasuaki

2012-11-06

88

Method Research Study 3, Demand Analyses. An Evaluation of Analytical Methods for Water and Wastewater.  

National Technical Information Service (NTIS)

In the study the demand parameters, chemical oxygen demand, total organic carbon, and biochemical oxygen demand, were tested to measure the accuracy and precision of the selected methods used in participating laboratories. The evaluation of results also p...

J. A. Winter

1971-01-01

89

Light-responsive polymer nanoreactors: a source of reactive oxygen species on demand  

NASA Astrophysics Data System (ADS)

Various domains present the challenges of responding to stimuli in a specific manner, with the desired sensitivity or functionality, and only when required. Stimuli-responsive systems that are appropriately designed can effectively meet these challenges. Here, we introduce nanoreactors that encapsulate photosensitizer-protein conjugates in polymer vesicles as a source of ``on demand'' reactive oxygen species. Vesicles made of poly(2-methyloxazoline)-poly(dimethylsiloxane)-poly(2-methyloxazoline) successfully encapsulated the photosensitizer Rose Bengal-bovine serum albumin conjugate (RB-BSA) during a self-assembly process, as demonstrated by UV-Vis spectroscopy. A combination of light scattering and transmission electron microscopy indicated that the nanoreactors are stable over time. They serve a dual role: protecting the photosensitizer in the inner cavity and producing in situ reactive oxygen species (ROS) upon irradiation with appropriate electromagnetic radiation. Illumination with appropriate wavelength light allows us to switch on/off and to control the production of ROS. Because of the oxygen-permeable nature of the polymer membrane of vesicles, ROS escape into the environment around vesicles, as established by electron paramagnetic resonance. The light-sensitive nanoreactor is taken up by HeLa cells in a Trojan horse fashion: it is nontoxic and, when irradiated with the appropriate laser light, produces ROS that induce cell death in a precise area corresponding to the irradiation zone. These nanoreactors can be used in theranostic approaches because they can be detected via the fluorescent photosensitizer signal and simultaneously produce ROS efficiently ``on demand''.Various domains present the challenges of responding to stimuli in a specific manner, with the desired sensitivity or functionality, and only when required. Stimuli-responsive systems that are appropriately designed can effectively meet these challenges. Here, we introduce nanoreactors that encapsulate photosensitizer-protein conjugates in polymer vesicles as a source of ``on demand'' reactive oxygen species. Vesicles made of poly(2-methyloxazoline)-poly(dimethylsiloxane)-poly(2-methyloxazoline) successfully encapsulated the photosensitizer Rose Bengal-bovine serum albumin conjugate (RB-BSA) during a self-assembly process, as demonstrated by UV-Vis spectroscopy. A combination of light scattering and transmission electron microscopy indicated that the nanoreactors are stable over time. They serve a dual role: protecting the photosensitizer in the inner cavity and producing in situ reactive oxygen species (ROS) upon irradiation with appropriate electromagnetic radiation. Illumination with appropriate wavelength light allows us to switch on/off and to control the production of ROS. Because of the oxygen-permeable nature of the polymer membrane of vesicles, ROS escape into the environment around vesicles, as established by electron paramagnetic resonance. The light-sensitive nanoreactor is taken up by HeLa cells in a Trojan horse fashion: it is nontoxic and, when irradiated with the appropriate laser light, produces ROS that induce cell death in a precise area corresponding to the irradiation zone. These nanoreactors can be used in theranostic approaches because they can be detected via the fluorescent photosensitizer signal and simultaneously produce ROS efficiently ``on demand''. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr32380j

Baumann, Patric; Balasubramanian, Vimalkumar; Onaca-Fischer, Ozana; Sienkiewicz, Andrzej; Palivan, Cornelia G.

2012-12-01

90

Experimental study of a CW chemical oxygen-iodine laser  

SciTech Connect

Through experimentation, a continuous wave oxygen-iodine chemical laser was achieved. When the amount of chlorine flow was 50mmol/s, the output power reached 1kW. In conjunction with this, measurements were made of beam divergence angles, investigating the relationships between beam divergence angles and power as well as cavity reflector curvature radii.

Sang, F.; Gu, C.

1995-11-21

91

Cutting performance of a chemical oxygen-iodine laser  

Microsoft Academic Search

Chemical Oxygen-Iodine Laser (COIL) is a member of the class of high power lasers for industrial applications, including the materials processing tasks of high speed cutting and drilling. COIL technology has received considerable interest over the last several years due to its short, fiber- deliverable wavelength (1.315 microns), scalability to very high powers (tens of kilowatts, cw), and demonstrated nearly

William P. Latham; James A. Rothenflue; Charles A. Helms; Aravinda Kar; David L. Carroll

1998-01-01

92

Research on advanced chemical and discharge oxygen-iodine lasers  

NASA Astrophysics Data System (ADS)

Generation of singlet oxygen and atomic iodine for operation of the chemical or discharge oxygen-iodine laser (COIL/DOIL) is described, employing novel methods and device configurations proposed in our laboratory. A centrifugal spray generator of singlet oxygen was developed, based on the conventional reaction between chlorine and basic hydrogen peroxide. Recent results of theoretical and experimental investigation of the generator parameters are presented. A new conception of the discharge generator of singlet oxygen was initiated, based on a combined DC arc jet and RF discharge techniques. Principle of the generator currently developed and constructed is described. A new device configuration was designed for the alternative method of atomic iodine generation using a radiofrequency discharge decomposition of iodine compounds like CH3I or CF3I. Some recent experimental results of this research are also presented.

Kodymová, Jarmila; Jirásek, Vít; Schmiedberger, Josef; Spalek, Otomar; Censký, Miroslav

2009-02-01

93

Chemical arms treaty makes unprecedented demands of industry  

Microsoft Academic Search

It took nearly a quarter of a century of grueling negotiations to craft the text of the comprehensive and verifiable chemical weapons treaty. But that may have been the easy part. Now representatives from about 90 of the more than 140 nations that have signed the treaty are at The Hague participating in a two-year exercise called the Preparatory Commission,

Ember

1993-01-01

94

Comparison of Instream and Laboratory Methods of Measuring Sediment Oxygen Demand  

USGS Publications Warehouse

Sediment oxygen demand (SOD) was determined at three sites in a gravel-bottomed central Missouri stream by: (1) two variations of an instream method, and (2) a laboratory method. SOD generally was greatest by the instream methods, which are considered more accurate, and least by the laboratory method. Disturbing stream sediment did not significantly decrease SOD by the instream method. Temperature ranges of up to 12 degree Celsius had no significant effect on the SOD. In the gravel-bottomed stream, the placement of chambers was critical to obtain reliable measurements. SOD rates were dependent on the method; therefore, care should be taken in comparing SOD data obtained by different methods. There is a need for a carefully researched standardized method for SOD determinations.

Hall, Dennis, C.; Berkas, Wayne, R.

1988-01-01

95

The effect of chamber mixing velocity on bias in measurement of sediment oxygen demand rates in the Tualatin River basin, Oregon  

USGS Publications Warehouse

Three sediment oxygen demand (SOD) measurement chambers were deployed in the Tualatin River near Tigard, Oregon, at river mile 10 in August 2000. SOD rates were calculated for three different circulation velocities during each chamber deployment. The SOD rate at each velocity was calculated from a graph of dissolved oxygen concentration versus elapsed time. An acoustic doppler current profiler (ADCP) was used to measure stream discharge and near-bottom water velocities in the Tualatin at river mile 10 and at two upstream locations. Measured river and chamber velocities were similar, indicating that results from the chambers were representative of instream effects. At low to moderate chamber circulation velocities (less than about 7.5 centimeters per second), the measured SOD rate appeared to be only slightly affected by the circulation velocity, indicating that the measured rates reflect the rate of oxygen utilization by chemical and biological reactions in the sediment rather than the rate of physical transport of oxygen to the sediment-water interface. Above about 7.5 centimeters per second, however, the measured oxygen depletion rate was affected by the circulation velocity, as sufficient energy was generated within the chamber to resuspend bottom sediment, as evidenced by increased turbidity. The resuspended sediment particles contributed to the measured oxygen loss rate by increasing the surface area of decomposing material in contact with the water column, resulting in a measured SOD rate that was anomalously high. Two different alignments of the chamber circulation diffusers were tested. With both diffuser alignments, SOD rates were similar at circulation velocities low enough to avoid sediment resuspension. The same resuspension effect probably exists in the Tualatin River during storm-runoff events following prolonged periods of low flow, when increased stream velocity may result in the resuspension of bottom sediments. The resuspension causes increased turbidity and increased oxygen demand, resulting in lower instream dissolved oxygen concentrations

Doyle, Micelis C.; Rounds, Stewart

2003-01-01

96

Development of a chemical oxygen - iodine laser with production of atomic iodine in a chemical reaction  

SciTech Connect

The alternative method of atomic iodine generation for a chemical oxygen - iodine laser (COIL) in chemical reactions with gaseous reactants is investigated experimentally. The influence of the configuration of iodine atom injection into the laser cavity on the efficiency of the atomic iodine generation and small-signal gain is studied. (lasers)

Censky, M; Spalek, O; Jirasek, V; Kodymova, J [Institute of Physics, Czech Academy of Sciences, Prague (Czech Republic); Jakubec, I [Institute of Inorganic Chemistry, Czech Academy of Sciences, Rez (Czech Republic)

2009-11-30

97

Development of photocatalytic biosensor for the evaluation of biochemical oxygen demand.  

PubMed

The photocatalytic biosensor of flow system using semiconductor TiO2 was developed to evaluate biochemical oxygen demand (BOD) levels in river water. Photocatalysis of sample was carried out in a photoreactor with TiO2 and a 6W black-light blue fluorescent tube as light source. Sample from a photoreactor outlet was measured by an oxygen electrode with a biofilm. The sensor response of photocatalytic biosensor was between 5 and 10 min depending on concentration of biochemical in the samples. At BOD of 1 mgl-1, the sensor response increased 1.33-fold in comparison with that without photocatalysis. The degradation of tannic acid and humic acid with photocatalysis were 51.8 and 38.4%, respectively. Gum arabic and linear alkylbenzene sulfonate (LAS) were degraded a little, but gave the responses of more than double to the sensor. Free radicals yielded by photocatalysis in a photoreactor did not affect the sensor response because their lifetime is extremely short. Fairly good correlation (r=0.983) between the sensor method and the conventional method was obtained for test samples. This biosensor using photocatalytic pretreatment improved the sensitivity. PMID:15967352

Chee, Gab-Joo; Nomura, Yoko; Ikebukuro, Kazunori; Karube, Isao

2005-07-15

98

Time-resolved oxygen production by PSII: chasing chemical intermediates  

Microsoft Academic Search

Photosystem II (PSII) produces dioxygen from water in a four-stepped process, which is driven by four quanta of light and catalysed by a Mn-cluster and tyrosine Z. Oxygen is liberated during one step, coined S3?S0. Chemical intermediates on the way from reversibly bound water to dioxygen have not yet been tracked, however, a break in the Arrhenius plot of the

Jürgen Clausen; Richard J. Debus; Wolfgang Junge

2004-01-01

99

78 FR 1765 - Requirements for Chemical Oxygen Generators Installed on Transport Category Airplanes  

Federal Register 2010, 2011, 2012, 2013

...or on the distribution of power and responsibilities among...d) Each chemical oxygen generator or its installation must be...any attempt to access the generator would be immediately obvious...25.1450 Chemical oxygen generators. * * * * *...

2013-01-09

100

Spatial and Temporal Variability of Benthic Oxygen Demand and Nutrient Regeneration in an Anthropogenically Impacted New England Estuary  

Microsoft Academic Search

Strong benthic–pelagic coupling is an important characteristic of shallow coastal marine ecosystems. Building upon a rich\\u000a history of benthic metabolism data, we measured oxygen uptake and nutrient fluxes across the sediment–water interface along\\u000a a gradient of water column primary production in Narragansett Bay, RI (USA). Despite the strong gradients seen in water column\\u000a production, sediment oxygen demand (SOD) and benthic

Robinson W. Fulweiler; Scott W. Nixon; Betty A. Buckley

2010-01-01

101

Removal of solids and oxygen demand from aquaculture wastewater with a constructed wetland system in the start-up phase.  

PubMed

A pilot-scale, constructed wetland system consisting of a free water surface (FWS) and a subsurface flow (SF) wetland operated in series was set up for treating aquaculture farm wastewater. This study examined the system start-up phenomena and evaluated its performance in removing suspended solids, algae, and chemical oxygen demand (COD) under various hydraulic loading rates (1.8 to 13.5 cm/d). The SF wetland achieved stable effluent qualities without an adaptation period, while the FWS wetland required approximately 5 months to reach consistent removal levels for suspended solids and algae. Macrophyte density was a critical factor affecting the reduction of suspended solids and chlorophyll for the FWS wetland, but not for the SF wetland. Suspended solids removals in both of the wetlands and the combined system (47 to 86%) decreased significantly as the hydraulic loading rate increased, strongly following the first-order mass-decrease equation. Phytoplankton solids (biomass and detritus) were a primary source of suspended solids in the aquaculture wastewater. Both chlorophyll reduction (76 to 95%) and COD removal (25 to 55%) in the constructed wetland system were apparently not affected by hydraulic loading. While algae died out because of limited sunlight in both wetlands, algae detritus probably still contributed fine particles that were difficult to remove from the water by either filtering or settling out. Removed suspended solids did not result in the increase of COD and nutrients, indicating that further solids stabilization occurred in the wetland system. PMID:12043970

Lin, Ying-Feng; Jing, Shuh-Ren; Lee, Der-Yuan; Wang, Tze-Wen

102

PROPOSED MODIFICATIONS OF K2-TEMPERATURE RELATION AND LEAST SQUARES ESTIMATES OF BOD (BIOCHEMICAL OXYGEN DEMAND) PARAMETERS  

EPA Science Inventory

A technique is presented for finding the least squares estimates for the ultimate biochemical oxygen demand (BOD) and rate coefficient for the BOD reaction without resorting to complicated computer algorithms or subjective graphical methods. This may be used in stream water quali...

103

Novel mixing nozzles for supersonic chemical oxygen iodine laser  

NASA Astrophysics Data System (ADS)

Mixing enhancement technique of supersonic chemical oxygen-iodine laser (COIL) is studied. The difficulty of supersonic mixing due to the compressibility of the fluid has been overcome by the introduction of streamwise vortex into the flow. The developed nozzle is a staggered array of wedges, looks like "X" letter from the side of the flow duct. Computational fluid dynamics (CFD) is employed for the design optimization of the proposed mixing nozzle. A remarkable mixing condition is found when iodine injector is located at the exit plane of the mixing nozzle. Experiments are conducted and good agreement with calculation is obtained in terms of iodine molecule distribution. A 266W of output power with chemical efficiency of 14.6% is obtained and good mixing capability of the proposed nozzle design is confirmed.

Hirata, Takayuki; Endo, Masamori; Shinoda, Kazuhiko; Osaka, Tatsuo; Nanri, Kenzo; Takeda, Shuzaburo; Fujioka, Tomoo

2003-12-01

104

76 FR 12556 - Airworthiness Directives; Various Transport Category Airplanes Equipped With Chemical Oxygen...  

Federal Register 2010, 2011, 2012, 2013

...equipped with any chemical oxygen generator installed in any lavatory...be notified that the oxygen generators in the lavatories had been...or on the distribution of power and responsibilities among...equipped with any chemical oxygen generator installed in any...

2011-03-08

105

Quantitative determination of oxygen yield in a chemical oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

With the advent of the Airborne Laser program, the emphasis of chemical oxygen-iodine laser (COIL) research has shifted toward improving the overall efficiency. A key component of COIL is the singlet-oxygen generator (SOG). To asses the efficiency of the SOG an accurate method of determining the yield of O2((alpha) 1(Delta) g),[O2((alpha) 1(Delta) g)]/[O2(total)] where [O2(total)]equals[O2((alpha) 1(Delta) g)]+[O2(X3(Sigma) g-)], has been developed. Absorption measurements of ground-state oxygen utilizing the magnetic-dipole transition, O2(X3(Sigma) g-) at 763 nm, have been obtained using a diode laser in conjunction with a multiple-pass Herriot-cell on a 10 kW class supersonic SOIL (RADICL). When RADICL is configured with a 0.35' throat, 15' diskpack, and a medium volume transition duct, with a diluent ratio (He:O2) of 3:1, the yield of O2((alpha) 1(Delta) g) in the diagnostic duct is 0.41 +/- 0.02.

Kendrick, K. R.; Helms, Charles A.; Quillen, B.; Copland, R. J.

1998-05-01

106

Simulation of dissolved oxygen and biochemical oxygen demand, Plantation Canal, Broward County, Florida with an evaluation of the QUAL-I model for use in south Florida  

USGS Publications Warehouse

A mathematical model; QUAL-I, developed by the Texas Water Development Board, was evaluated as a management tool in predicting the spatial and temporal distribution of dissolved oxygen and biochemical oxygen demand in Plantation Canal. Predictions based on the QUAL-I model, which was verified only against midday summer-flow conditions, showed that improvement of quality of inflows from sewage treatment plants and use of at least 130 cubic feet per second of dilution water would improve water quality in the canal significantly. The model was not fully amenable to use on Plantation Canal because: (1) it did not consider photosynthetic production, nitrification, and benthic oxygen demand as sources and sinks of oxygen; (2) the model assumptions of complete mixing, transport, and steady state were not met; and (3) the data base was inadequate because it consisted of only one set of data for each case. However, it was felt that meaningful results could be obtained for some sets of conditions. (Woodard-USGS)

Russo, Thomas N.; McQuivey, Raul S.

1975-01-01

107

Effects of time pressure and precision demands during computer mouse work on muscle oxygenation and position sense  

Microsoft Academic Search

The present study investigated the effects of time pressure and precision demands during computer mouse work on muscle oxygenation and position sense in the upper extremity. Twenty-four healthy subjects (12 males and 12 females) performed a 45-min standardized mouse-operated computer task on two occasions. The task consisted of painting rectangles that were presented on the screen. On one occasion, time

M. Heiden; E. Lyskov; M. Djupsjöbacka; F. Hellström; A. G. Crenshaw

2005-01-01

108

Sources and transport of sediment, nutrients, and oxygen-demanding substances in the Minnesota River basin, 1989-92  

USGS Publications Warehouse

The Minnesota River, 10 major tributaries, and 21 springs were sampled to determine the sources and transport of sediment, nutrients, and oxygen- demanding substances. The study was part of a four-year assessment of non-point source pollution in the Minnesota River Basin. Runoff from tributary watersheds was identified as the primary source of suspended sediment and nutrients in the Minnesota River mainstem. Suspended-sediment, phosphorus, and nitrate concentrations were elevated in all major tributaries during runoff, but tributaries in the south-central and eastern part of the basin produce the highest annual loading to the mainstem because of higher annual precipitation and runoff in that part of the basin. Particle-size analyses showed that most of the suspended sediment in transport consisted of silt- and clay-size material. Phosphorus enrichment was indicated throughout the mainstem by total phosphorus concentrations that ranged from 0.04 to 0.48 mg/L with a median value of 0.22 mg/L, and an interquartile range of 0.15 to 0.29 mg/L. Nitrate concentrations periodically exceeded drinking water standards in tributaries draining the south-central and eastern part of the basin. Oxygen demand was most elevated during periods of summer low flow. Correlations between levels of biochemical oxygen demand and levels of algal productivity suggest that algal biomass comprises much of the oxygen-demanding material in the mainstem. Transport of sediment, nutrients, and organic carbon within the mainstem was found to be conservative, with nearly all tributary inputs being transported downstream. Uptake and utilization of nitrate and orthophosphorus was indicated during low flow, but at normal and high flow, inputs of these constituents greatly exceeded biological utilization.

Payne, G. A.

1994-01-01

109

A model of oxygen uptake kinetics in response to exercise: Including a means of calculating oxygen demand\\/deficit\\/debt  

Microsoft Academic Search

We present a new model of the underlying dynamics of the oxygen uptake \\u000a $$\\\\dot VO_2 (\\\\upsilon , t)$$\\u000a kinetics for various exercise intensities. This model is in the form of a set of nonlinear coupled vector fields for the\\u000a \\u000a $$\\\\ddot VO_2 (\\\\upsilon , t)$$\\u000a and \\u000a $$\\\\dot \\\\upsilon $$\\u000a , the derivative of the exercise intensity with respect to time. We

J. R. Stirling; M. S. Zakynthinaki; B. Saltin

2005-01-01

110

Chemical-looping with oxygen uncoupling using CuO\\/ZrO 2 with petroleum coke  

Microsoft Academic Search

Oxygen carrier particles of CuO\\/ZrO2 were reacted with petroleum coke using chemical-looping with oxygen uncoupling (CLOU). The fuel was burnt in gas-phase oxygen released from the oxygen carrier particles during the fuel oxidation. The particles were then regenerated in 5–21% oxygen. In this process, the carbon dioxide from the combustion is inherently separated from the rest of the flue gases

Tobias Mattisson; Henrik Leion; Anders Lyngfelt

2009-01-01

111

Aircraft and runway deicers at General Mitchell International Airport, Milwaukee, Wisconsin, USA. 1. Biochemical oxygen demand and dissolved oxygen in receiving streams.  

PubMed

Aircraft and runway deicers are used during cold weather at many of the world's airports to facilitate safe air travel. Propylene glycol-, ethylene glycol-, and urea-based deicers are known to have very high biochemical oxygen demand. At General Mitchell International Airport (GMIA) in Milwaukee, Wisconsin, USA, deicer application, water chemistry, and dissolved oxygen (DO) data were collected for two deicing seasons in order to evaluate and define premanagement water quality parameters prior to the implementation of a glycol management program. Calculations using stream-monitoring data during a controlled release of deicer provided an estimate of 0.8/d for the first-order decay rate constant, substantially higher than published laboratory test results. For eight precipitation events with deicing activities, between 2.4 and 99% of propylene and ethylene glycol applied to aircraft was delivered directly to receiving streams. The percentage of glycol runoff during an event increased with increasing storm-flow volume. Elevated concentrations of glycol and biochemical oxygen demand were measured downstream from the airport. However, the frequency of low DO concentrations in the receiving streams is comparable with that at an upstream reference site. This is possibly due to slowed bacteria metabolism at low water temperatures, short travel times, and dilution from downstream tributaries. PMID:11434287

Corsi, S R; Booth, N L; Hall, D W

2001-07-01

112

Aircraft and runway deicers at General Mitchell International Airport, Milwaukee, Wisconsin, USA. 1. Biochemical oxygen demand and dissolved oxygen in receiving streams  

USGS Publications Warehouse

Aircraft and runway deicers are used during cold weather at many of the world's airports to facilitate safe air travel. Propylene glycol-, ethylene glycol-, and urea-based deicers are known to have very high biochemical oxygen demand. At General Mitchell International Airport (GMIA) in Milwaukee, Wisconsin, USA, deicer application, water chemistry, and dissolved oxygen (DO) data were collected for two deicing seasons in order to evaluate and define premanagement water quality parameters prior to the implementation of a glycol management program. Calculations using stream-monitoring data during a controlled release of deicer provided an estimate of 0.8/d for the first-order decay rate constant, substantially higher than published laboratory test results. For eight precipitation events with deicing activities, between 2.4 and 99% of propylene and ethylene glycol applied to aircraft was delivered directly to receiving streams. The percentage of glycol runoff during an event increased with increasing storm-flow volume. Elevated concentrations of glycol and biochemical oxygen demand were measured downstream from the airport. However, the frequency of low DO concentrations in the receiving streams is comparable with that at an upstream reference site. This is possibly due to slowed bacteria metabolism at low water temperatures, short travel times, and dilution from downstream tributaries.

Corsi, S. R.; Booth, N. L.; Hall, D. W.

2001-01-01

113

Effects of Enhanced External Counterpulsation on Arterial Stiffness and Myocardial Oxygen Demand in Patients with Chronic Angina Pectoris  

PubMed Central

Enhanced external counterpulsation (EECP) is a non-invasive modality for treatment of symptomatic coronary disease (CAD) in patients not amenable to revascularization procedures. However, the mechanism(s) underlying the benefits of EECP remain unknown. We hypothesized that reductions in arterial stiffness and aortic wave reflection are a therapeutic target for EECP. CAD patients with chronic angina pectoris were randomized (2:1 ratio) to either 35 1-hr sessions of EECP (n=28) or Sham-EECP (n=14). Central and peripheral arterial pulse wave velocity (PWV) and aortic wave reflection (augmentation index; AIx) were measured using applanation tonometry before, and after 17 and 35 1-hr treatment sessions. Wasted left ventricular pressure energy and aortic systolic tension time index, markers of left-ventricular myocardial oxygen demand were derived from the synthesized aortic pressure wave. Exercise duration, anginal threshold, and peak oxygen consumption were measured using a graded treadmill test. Central arterial stiffness and AIx were reduced following 17- and 35-sessions in the treatment group. Measures of peripheral arterial stiffness were reduced following 35 sessions in the treatment group. Changes in aortic pressure wave reflection resulted in decreased measures of myocardial oxygen demand and wasted left ventricular energy. No changes in either central or peripheral arterial stiffness were observed in the Sham group. Furthermore, measures of exercise capacity were improved in the EECP group, but unchanged in the Sham group. In conclusion, EECP therapy reduces central and peripheral arterial stiffness, which may explain improvements in myocardial oxygen demand in patients with chronic angina pectoris following treatment.

Casey, Darren P.; Beck, Darren T.; Nichols, Wilmer W.; Conti, C. Richard; Choi, Calvin Y.; Khuddus, Matheen A.; Braith, Randy W.

2011-01-01

114

Effects of enhanced external counterpulsation on arterial stiffness and myocardial oxygen demand in patients with chronic angina pectoris.  

PubMed

Enhanced external counterpulsation (EECP) is a noninvasive technique for treatment of symptomatic coronary artery disease in patients not amenable to revascularization procedures. However, the mechanisms underlying the benefits of EECP remain unknown. We hypothesized that decreases in arterial stiffness and aortic wave reflection are a therapeutic target for EECP. Patients with coronary artery disease and chronic angina pectoris were randomized (2:1 ratio) to 35 1-hour sessions of EECP (n = 28) or sham EECP (n = 14). Central and peripheral arterial pulse-wave velocity and aortic wave reflection (augmentation index) were measured using applanation tonometry before, and after 17 and 35 1-hour treatment sessions. Wasted left ventricular pressure energy and aortic systolic tension-time index, markers of left-ventricular myocardial oxygen demand, were derived from the synthesized aortic pressure wave. Exercise duration, anginal threshold, and peak oxygen consumption were measured using a graded treadmill test. Central arterial stiffness and augmentation index were decreased after 17 and 35 sessions in the treatment group. Measurements of peripheral arterial stiffness were decreased after 35 sessions in the treatment group. Changes in aortic pressure wave reflection resulted in decreased measurements of myocardial oxygen demand and wasted left ventricular energy. No changes in central or peripheral arterial stiffness were observed in the sham group. Furthermore, measurements of exercise capacity were improved in the EECP group but unchanged in the sham group. In conclusion, EECP therapy decreases central and peripheral arterial stiffness, which may explain improvements in myocardial oxygen demand in patients with chronic angina pectoris after treatment. PMID:21420062

Casey, Darren P; Beck, Darren T; Nichols, Wilmer W; Conti, C Richard; Choi, Calvin Y; Khuddus, Matheen A; Braith, Randy W

2011-03-17

115

Impact of the renewable oxygenate standard for reformulated gasoline on ethanol demand, energy use, and greenhouse gas emissions  

SciTech Connect

To assure a place for renewable oxygenates in the national reformulated gasoline (RFG) program, the US Environmental Protection Agency has promulgated the renewable oxygenate standard (ROS) for RFG. It is assumed that ethanol derived from corn will be the only broadly available renewable oxygenate during Phase I of the RFG program. This report analyzes the impact that the ROS could have on the supply of ethanol, its transported volume, and its displacement from existing markets. It also considers the energy and crude oil consumption and greenhouse gas (GHG) emissions that could result from the production and use of various RFGs that could meet the ROS requirements. The report concludes that on the basis of current and projected near-term ethanol capacity, if ethanol is the only available renewable oxygenate used to meet the requirements of the ROS, diversion of ethanol from existing use as a fuel is likely to be necessary. Year-round use of ethanol and ETBE would eliminate the need for diversion by reducing winter demand for ethanol. On an RFG-program-wide basis, using ethanol and ETBE to satisfy the ROS can be expected to slightly reduce fossil energy use, increase crude oil use, and have essentially no effect on GHG emissions or total energy use relative to using RFG oxygenated only with MTBE.

Stork, K.C.; Singh, M.K.

1995-04-01

116

Feasibility of high pressure operation and determination of the optimum gain zone in chemical oxygen-iodine lasers  

SciTech Connect

Use is made of a simple model to theoretically prove that there exist optimum values for small signal gains in chemical Oxygen-Iodine lasers dependent on overall system oxygen pressures. At the same time, the feasibility of chemical oxygen-iodine laser operations under high pressure is discussed. Finally, methods for determining optimum gain zones for chemical oxygen-iodine lasers are given.

Li, F.

1995-11-29

117

A new method for the determination of biological oxygen demand in domestic wastewater by headspace gas chromatography.  

PubMed

A headspace gas chromatographic method (HS-GC) has been developed for the determination of biological oxygen demand (BOD) in the water samples from domestic wastewater treatment plants. The method is based on measuring the remaining oxygen in the headspace of the sample (that has been seeded with microorganisms) in a closed container after a period of incubation. The relative standard deviation of the method in replicate testing was <4.9%. Further, the results differed by less than 6% when compared with the widely used reference method (the ISO standard) for determining BOD5. The limit of quantification in BODn testing was about 1.8 mg/L. The new method is simple and suitable for use in the batch sample testing for BODn measurement. PMID:23953613

Gu, Juan-Juan; Hu, Hui-Chao; Chai, Xin-Sheng; Tian, Ying-Xin; Barnes, Donald G; Huang, Shaobin

2013-08-01

118

Discriminating between west-side sources of nutrients and organiccarbon contributing to algal growth and oxygen demand in the San JoaquinRiver  

SciTech Connect

The purpose of this study was to investigate the Salt and Mud Slough tributaries as sources of oxygen demanding materials entering the San Joaquin River (SJR). Mud Slough and Salt Slough are the main drainage arteries of the Grasslands Watershed, a 370,000-acre area west of the SJR, covering portions of Merced and Fresno Counties. Although these tributaries of the SJR are typically classified as agricultural, they are also heavily influenced by Federal, State and private wetlands. The majority of the surface water used for both irrigation and wetland management in the Grassland Watershed is imported from the Sacramento-San Joaquin Delta through the Delta-Mendota Canal. In this study, they measured algal biomass (as chlorophyll a), organic carbon, ammonia, biochemical oxygen demand (BOD), and other measures of water quality in drainage from both agricultural and wetland sources at key points in the Salt Slough and Mud Slough tributaries. This report includes the data collected between June 16th and October 4th, 2001. The objective of the study was to compare agricultural and wetland drainage in the Grasslands Watershed and to determine the relative importance of each return flow source to the concentration and mass loading of oxygen demanding materials entering the SJR. Additionally, they compared the quality of water exiting our study area to water entering our study area. This study has demonstrated that Salt and Mud Sloughs both contribute significant amounts of oxygen demand to the SJR. Together, these tributaries could account for 35% of the oxygen demand observed below their confluence with the SJR. This study has characterized the sources of oxygen demanding materials entering Mud Slough and evaluated the oxygen demand conditions in Salt Slough. Salt Slough was found to be the dominant source of oxygen demand load in the study area, because of the higher flows in this tributary. The origins of oxygen demand in Salt Slough still remain largely uninvestigated and the seasonal oxygen demand loading pattern remains unexplained. An expanded investigation of the Salt Slough watershed is warranted, because of the importance of this watershed to the oxygen demand load entering the SJR.

Wstringfellow@lbl.gov

2002-07-24

119

Metabolic demand, oxygen supply, and critical temperatures in the Antarctic bivalve Laternula elliptica.  

PubMed

Oxygen consumption (Mo(2)), heartbeat rate and form, and circulating hemolymph oxygen content were measured in relation to temperature in the large Antarctic infaunal bivalve Laternula elliptica. After elevations in temperature from 0 degrees to 3 degrees, 6 degrees, and then 9 degrees C, Mo(2) and heartbeat rate rose to new levels, whereas maximum circulating hemolymph oxygen content fell. At 0 degrees C, Mo(2) was 19.6 micromol O(2) h(-1) for a standard animal of 2-g tissue ash-free dry mass, which equates to a 8.95-g tissue dry-mass or 58.4-g tissue wet-mass animal. Elevation of metabolism following temperature change had acute Q(10) values between 4.1 and 5, whereas acclimated figures declined from 3.4 (between 0 degrees and 3 degrees C) to 2.2 (3 degrees -6 degrees C) and 1.9 (6 degrees -9 degrees C). Heartbeat rate showed no acclimation following temperature elevations, with Q(10) values of 3.9, 3.2, and 4.3, respectively. Circulating hemolymph oxygen content declined from 0 degrees to 3 degrees and 6 degrees C but stayed at a constant Po(2) (73-78 mmHg) and constant proportion ( approximately 50%) of the oxygen content of the ambient water. At 9 degrees C, Mo(2) and heartbeat rate both peaked at values 3.3 times those measured at 0 degrees C, which may indicate aerobic scope in this species. After these peaks, both measures declined rapidly over the ensuing 5 d to the lowest measured in the study, and the bivalves began to die. Hemolymph oxygen content fell dramatically at 9 degrees C to values between 2% and 12% of ambient water O(2) content and had a maximum Po(2) of around 20 mmHg. These data indicate an experimental upper lethal temperature of 9 degrees C and a critical temperature, where a long-term switch to anaerobic metabolism probably occurs, of around 6 degrees C for L. elliptica. Concurrent measures of mitochondrial function in the same species had indicated strong thermal sensitivity in proton leakage costs, and our data support the hypothesis that as temperature rises, mitochondrial maintenance costs rapidly outstrip oxygen supply mechanisms in cold stenothermal marine species. PMID:12024288

Peck, Lloyd S; Pörtner, Hans O; Hardewig, Iris

120

Red SOX (Singlet Oxygen) Laser: A Chemically-Pumped, 0.76 Micrometer Singlet Oxygen Laser.  

National Technical Information Service (NTIS)

The feasibility of a red singlet oxygen laser based on production of (b) state singlet oxygen by the electronic energy pooling reaction of (a) state singlet oxygen was investigated. A microwave discharge-flow system for studying the quenching kinetics of ...

G. E. Busch M. B. Knickelbein

1986-01-01

121

Respiratory plasticity in response to changes in oxygen supply and demand.  

PubMed

Aerobic organisms maintain O(2) homeostasis by responding to changes in O(2) supply and demand in both short and long time domains. In this review, we introduce several specific examples of respiratory plasticity induced by chronic changes in O(2) supply (environmental hypoxia or hyperoxia) and demand (exercise-induced and temperature-induced changes in aerobic metabolism). These studies reveal that plasticity occurs throughout the respiratory system, including modifications to the gas exchanger, respiratory pigments, respiratory muscles, and the neural control systems responsible for ventilating the gas exchanger. While some of these responses appear appropriate (e.g., increases in lung surface area, blood O(2) capacity, and pulmonary ventilation in hypoxia), other responses are potentially harmful (e.g., increased muscle fatigability). Thus, it may be difficult to predict whole-animal performance based on the plasticity of a single system. Moreover, plastic responses may differ quantitatively and qualitatively at different developmental stages. Much of the current research in this field is focused on identifying the cellular and molecular mechanisms underlying respiratory plasticity. These studies suggest that a few key molecules, such as hypoxia inducible factor (HIF) and erythropoietin, may be involved in the expression of diverse forms of plasticity within and across species. Studying the various ways in which animals respond to respiratory challenges will enable a better understanding of the integrative response to chronic changes in O(2) supply and demand. PMID:21672862

Bavis, Ryan W; Powell, Frank L; Bradford, Aidan; Hsia, Connie C W; Peltonen, Juha E; Soliz, Jorge; Zeis, Bettina; Fergusson, Elizabeth K; Fu, Zhenxing; Gassmann, Max; Kim, Cindy B; Maurer, Jana; McGuire, Michelle; Miller, Brooke M; O'Halloran, Ken D; Paul, Rüdiger J; Reid, Stephen G; Rusko, Heikki K; Tikkanen, Heikki O; Wilkinson, Katherine A

2007-07-23

122

On a new method for chemical production of iodine atoms in a chemical oxygen-iodine laser  

SciTech Connect

A new method is proposed for generating iodine atoms in a chemical oxygen-iodine laser. The method is based on a branched chain reaction of dissociation of the alkyl iodide CH{sub 3}I in a medium of singlet oxygen and chlorine. (active media)

Andreeva, Tamara L; Kuznetsova, S V; Maslov, A I; Sorokin, Vadim N [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2004-11-30

123

The use of ilmenite as an oxygen carrier in chemical-looping combustion  

Microsoft Academic Search

The feasibility of using ilmenite as oxygen carrier in chemical-looping combustion has been investigated. It was found that ilmenite is an attractive and inexpensive oxygen carrier for chemical-looping combustion. A laboratory fluidized-bed reactor system, simulating chemical-looping combustion by exposing the sample to alternating reducing and oxidizing conditions, was used to investigate the reactivity. During the reducing phase, 15g of ilmenite

Henrik Leion; Anders Lyngfelt; Marcus Johansson; Erik Jerndal; Tobias Mattisson

2008-01-01

124

Galactic Chemical Evolution of Oxygen in Interstellar Dust and Gas  

NASA Astrophysics Data System (ADS)

Models of the isotopic evolution of oxygen in interstellar dust and gas show that the average ISM dust can be enriched or depleted by several per cent in oxygen-16 relative to the gas. The results depend on timescales and stellar yield inputs.

Meyer, B. S.

2013-09-01

125

Oxygen diffusion in basalt and andesite melts: experimental results and discussion of chemical versus tracer diffusion  

NASA Astrophysics Data System (ADS)

Chemical diffusion coefficients for oxygen in melts of Columbia River basalt (Ice Harbor Dam flow) and Mt. Hood andesite have been determined at 1 atm. The diffusion model is that of sorption or desorption of oxygen into a sphere of uniform initial concentration from a constant and semi-infinite atmosphere. The experimental design utilizes a thermogravimetric balance to monitor the rate of weight change arising from the response of the sample redox state to an imposed fO2. Oxygen diffusion coefficients are approximately an order-ofmagnitude greater for basaltic melt than for andesitic melt. At 1260° C, the oxygen diffusion coefficients are: D=1.65×10-6cm2/s and D=1.43×10-7cm2/s for the basalt and andesite melts, respectively. The high oxygen diffusivity in basaltic melt correlates with a high ratio of nonbridging oxygen/tetrahedrally coordinated cations, low melt viscosity, and high contents of network-modifying cations. The dependence of the oxygen diffusion coefficient on temperature is: D=36.4exp(-51,600±3200/ RT)cm2/s for the basalt and D=52.5exp(-60,060±4900/ RT)cm2/s for the andesite ( R in cal/deg-mol; T in Kelvin). Diffusion coefficients are independent of the direction of oxygen diffusion (equilibrium can be approached from extremely oxidizing or reducing conditions) and thus, melt redox state. Characteristic diffusion distances for oxygen at 1260° C vary from 10-2 to 102 m over the time interval of 1 to 106 years. A compensation diagram shows two distinct trends for oxygen chemical diffusion and oxygen tracer diffusion. These different linear relationships are interpreted as supporting distinct oxygen transport mechanisms. Because oxygen chemical diffusivities are generally greater than tracer diffusivities and their Arrhenius activation energies are less, transport mechanisms involving either molecular oxygen or vacancy diffusion are favored.

Wendlandt, Richard F.

1991-10-01

126

Development and performance of Cu-based oxygen carriers for chemical-looping combustion  

Microsoft Academic Search

Chemical-looping combustion (CLC) has the inherent property of separating the product CO2 from flue gases. Instead of air, it uses an oxygen carrier, usually in the form of a metal oxide, to provide oxygen for combustion. This paper focuses on the development and performance of a suitable Cu-based oxygen carrier for burning solid fuels using CLC. Carriers were made from

S. Y. Chuang; J. S. Dennis; A. N. Hayhurst; S. A. Scott

2008-01-01

127

Oxidation kinetics of chemically vapor-deposited silicon carbide in wet oxygen  

Microsoft Academic Search

The oxidation kinetics of chemically vapor-deposited SiC in dry oxygen and wet oxygen at temperatures between 1,200 and 1,400 C were monitored using thermogravimetric analysis. It was found that in a clean environment, 10% water vapor enhanced the oxidation kinetics of SiC only very slightly compared to rates found in dry oxygen. Oxidation kinetics were examined in terms of the

Elizabeth J. Opila

1994-01-01

128

LASERS, ACTIVE MEDIA: Calculation of the mixing chamber of an ejector chemical oxygen --- iodine laser  

Microsoft Academic Search

Gas parameters are calculated at the outlet of the mixing chamber of an ejector chemical oxygen---iodine laser with a nozzle unit consisting of nozzles of three types, which provides a total pressure of the active medium that substantially exceeds a pressure in the generator of singlet oxygen. This technique of forming the laser active medium substantially facilitates the ejection of

M. V. Zagidullin; V. D. Nikolaev

2001-01-01

129

Calculation of the mixing chamber of an ejector chemical oxygen - iodine laser  

Microsoft Academic Search

Gas parameters are calculated at the outlet of the mixing chamber of an ejector chemical oxygen-iodine laser with a nozzle unit consisting of nozzles of three types, which provides a total pressure of the active medium that substantially exceeds a pressure in the generator of singlet oxygen. This technique of forming the laser active medium substantially facilitates the ejection of

M V Zagidullin; V D Nikolaev

2001-01-01

130

Influence of oxygen-inhibited layer on dentin bond strength of chemical-cured resin composite.  

PubMed

This study evaluated the influence of an oxygen-inhibited layer on the surface free energies of three single-step self-etch adhesives and on the bond strength of chemical-cured resin. Adhesives were applied to bovine dentin and light irradiated, and the oxygen-inhibited layer was either retained or removed. Surface free energies were determined by measuring the contact angles of test liquids placed on the cured adhesives. Dentin bond strengths of chemical-cured resin with and without the oxygen-inhibited layer were measured. Ultrastructural observation of the restorative-dentin interface was made by scanning electron microscopy. For all surfaces, values of the estimated surface tension component, Lifshitz-Van der Waals force (?S (LW) ), were relatively constant. Values for the Lewis acid (?S (+) ) component increased slightly when the oxygen-inhibited layer was removed, whereas those of the Lewis base (?S (-) ) component decreased significantly. The bond strength of the chemical-cured resin composite was significantly higher in specimens without an oxygen-inhibited layer (7.6-8.0 MPa) than in those with an oxygen-inhibited layer (4.8-5.2 MPa). Small gaps between adhesive and resin composite were found for the group with an oxygen-inhibited layer. These results indicate that the absence of an oxygen-inhibited layer in single-step self-etch adhesives promotes higher dentin bond strength of the chemical-cured resin. PMID:24028599

Yamaji, Ayumi; Koga, Kensaku; Tsujimoto, Akimasa; Shimizu, Yusuke; Tsubota, Keishi; Takamizawa, Toshiki; Miyazaki, Masashi

2013-08-17

131

Chemical-looping with oxygen uncoupling for combustion of solid fuels  

Microsoft Academic Search

Chemical-looping with oxygen uncoupling (CLOU) is a novel method to burn solid fuels in gas-phase oxygen without the need for an energy intensive air separation unit. The carbon dioxide from the combustion is inherently separated from the rest of the flue gases. CLOU is based on chemical-looping combustion (CLC) and involves three steps in two reactors, one air reactor where

Tobias Mattisson; Anders Lyngfelt; Henrik Leion

2009-01-01

132

Generation of oxygen gradients in microfluidic devices for cell culture using spatially confined chemical reactions.  

PubMed

This paper reports a microfluidic device capable of generating oxygen gradients for cell culture using spatially confined chemical reactions with minimal chemical consumption. The microfluidic cell culture device is constructed by single-layer polydimethylsiloxane (PDMS) microfluidic channels, in which the cells can be easily observed by microscopes. The device can control the oxygen gradients without the utilization of bulky pressurized gas cylinders, direct addition of oxygen scavenging agents, or tedious gas interconnections and sophisticated flow control. In addition, due to the efficient transportation of oxygen within the device using the spatially confined chemical reactions, the microfluidic cell culture device can be directly used in conventional cell incubators without altering their gaseous compositions. The oxygen gradients generated in the device are numerically simulated and experimentally characterized using an oxygen-sensitive fluorescence dye. In this paper, carcinomic human alveolar basal epithelial (A549) cells have been cultured in the microfluidic device with a growth medium and an anti-cancer drug (Tirapazamine, TPZ) under various oxygen gradients. The cell experiment results successfully demonstrate the hyperoxia-induced cell death and hypoxia-induced cytotoxicity of TPZ. In addition, the results confirm the great cell compatibility and stable oxygen gradient generation of the developed device. Consequently, the microfluidic cell culture device developed in this paper is promising to be exploited in biological labs with minimal instrumentation to study cellular responses under various oxygen gradients. PMID:21915399

Chen, Yung-Ann; King, Andrew D; Shih, Hsiu-Chen; Peng, Chien-Chung; Wu, Chueh-Yu; Liao, Wei-Hao; Tung, Yi-Chung

2011-09-13

133

Chemical reactions and thermal stability of oxygen impurities on graphene  

NASA Astrophysics Data System (ADS)

Oxygen as an impurity is known to degrade conductivity in graphene, but annealing at moderate temperature reverses the effect. Here we report first-principles calculations of oxygen binding and reactions on graphene that elucidate the underlying physics. We find that two O atoms can form an O dimer that can desorb from graphene with an overall activation barrier of 1.3 eV. Oxygen can also be removed in a more complicated reaction in which C atoms in graphene are consumed. We find that structural defects such as Stone-Wales defect and grain boundaries show enhanced binding to O atoms due to the local strain, facilitating the O reaction. If H atoms coexist, an O atom can bind to an H atom forming an OH group, which can also be removed by thermal annealing due to the weak binding, resulting in defect-free graphene.

Wang, Bin; Pantelides, Sokrates

2012-02-01

134

Efficient generation in a chemical oxygen — iodine laser with a low buffer-gas flow rate  

Microsoft Academic Search

The efficient generation in a chemical oxygen — iodine laser (COIL) with a low buffer-gas flow rate for Mach numbers M ? 1 is demonstrated. The maximum output power of the COIL was 415 W for a molecular chlorine flow rate of 20 mmol s-1, which corresponds to a chemical efficiency ?ch =23%. It is shown that the substitution of

V N Azyazov; V S Safonov; N I Ufimtsev

2002-01-01

135

Efficient generation in a chemical oxygen - iodine laser with a low buffer-gas flow rate  

Microsoft Academic Search

The efficient generation in a chemical oxygen - iodine laser (COIL) with a low buffer-gas flow rate for Mach numbers M {<=} 1 is demonstrated. The maximum output power of the COIL was 415 W for a molecular chlorine flow rate of 20 mmol s⁻¹, which corresponds to a chemical efficiency η{sub ch} =23%. It is shown that the substitution

V N Azyazov; V S Safonov; N I Ufimtsev

2002-01-01

136

GENETIC ALGORITHMS AND OPTIMIZING CHEMICAL OXYGEN-IODINE LASERS  

Microsoft Academic Search

This paper presents results from the first known application of the genetic algorithm (GA) technique for optimizing the performance of a laser system (chemical, solid-state, or gaseous). The effects of elitism, single point and uniform crossover, creep mutation, different random number seeds, population size, niching and the number of children per pair of parents on the performance of the GA

David L. Carroll

1996-01-01

137

Atomic oxygen-MoS/sub 2/ chemical interactions  

SciTech Connect

The present study shows that, at 1.5 eV O-atom translation energy, SO/sub 2/ is generated and outgases from an anhydrous MoS/sub 2/surface with an initial reactivity nearly 50% that of kapton. The reaction of atomic oxygen with MoS/sub 2/ has little or no translational energy barier; i.e., thermally generated atomic oxygen reacts as readily as that having 1.5 eV of translational energy. It is also shown that water, present in the flowing afterglow apparatus used to study thermal O-atom reactivity, formed sulfates on the MoS/sub 2/ surface and that the sulfate is not likely in the form of sulfuric acid. These results imply that water dumps or outgasing in low earth orbit have the potential of forming sulfuric acid covered surfaces on MoS/sub 2/ lubricants. For MoS/sub 2/ films sputter-deposited at 50-70/degree/C, friction measurements show a high initial friction coefficient for O-atom exposed MoS/sub 2/ surfaces (up to 0.25) which drops to the normal low values after several cycles of operation in air and ultrahigh vacuum. For MoS/sub 2/ films deposited at 200/degree/C, the friction coefficient was not affected by the O-atom exposure. 11 refs., 3 figs.

Cross, J.B.; Martin, J.A.; Pope, L.E.; Koontz, S.L.

1989-01-01

138

Semi-specific Microbacterium phyllosphaerae-based microbial sensor for biochemical oxygen demand measurements in dairy wastewater.  

PubMed

Although the long incubation time of biochemical oxygen demand (BOD7) measurements has been addressed by the use of microbial biosensors, the resulting sensor-BOD values gained from the measurements with specific industrial wastewaters still underestimates the BOD value of such samples. This research aims to provide fast and more accurate BOD measurements in the dairy wastewater samples. Unlike municipal wastewater, wastewater from the dairy industry contains many substrates that are not easily accessible to a majority of microorganisms. Therefore, a bacterial culture, Microbacterium phyllosphaerae, isolated from dairy wastewater was used to construct a semi-specific microbial biosensor. A universal microbial biosensor based on Pseudomonas fluorescens, which has a wide substrate spectrum but is nonspecific to dairy wastewater, was used as a comparison. BOD biosensors were calibrated with OECD synthetic wastewater, and experiments with different synthetic and actual wastewater samples were carried out. Results show that the semi-specific M. phyllosphaerae-based microbial biosensor is more sensitive towards wastewaters that contain milk derivates and butter whey than the P. fluorescens-based biosensor. Although the M. phyllosphaerae biosensor underestimates the BOD7 value of actual dairy wastewaters by 25-32%, this bacterial culture is more suitable for BOD monitoring in dairy wastewater than P. fluorescens, which underestimated the same samples by 46-61%. PMID:22961489

Kibena, Elo; Raud, Merlin; Jõgi, Eerik; Kikas, Timo

2012-09-08

139

An optical biosensing film for biochemical oxygen demand determination in seawater with an automatic flow sampling system  

NASA Astrophysics Data System (ADS)

An on-line roboticized apparatus, including an optical biosensing film with an automatic flow sampling system, has been developed for biochemical oxygen demand (BOD) determination of seawater. The sensing film employed in the apparatus consisted of an organically modified silicate (ORMOSIL) film embedded with tri(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) perchlorate. Three species of microorganism cultivated from seawater were immobilized in an ORMOSIL-polyvinyl alcohol matrix. Possible factors affecting BOD determination were studied, including sampling frequency, temperature, pH and sodium chloride concentration. Based on measurements of the linear fluctuant coefficients and the reproducibility of its response to seawater, the BOD apparatus showed the advantages of high veracity and short response time. Generally, the linear fluctuant coefficient (R2) in the BOD range 0.2-40 mg l-1 was 0.9945 when using a glucose/glutamate (GGA) BOD standard solution. A reproducible response for the BOD sensing film of within ±2.8% could be obtained in the 2 mg l-1 GGA solution. The BOD apparatus was applied to the BOD determination of seawater, and the values estimated by this biosensing apparatus correlated well with those determined by the conventional 5 day BOD (BOD5) test.

Xin, Lingling; Wang, Xudong; Guo, Guangmei; Wang, Xiaoru; Chen, Xi

2007-09-01

140

A Study of New Catalytic Agents to Determine Chemical Oxygen Demand.  

National Technical Information Service (NTIS)

This study was made to find a catalyst to replace silver sulfate in the COD method in order to reduce the cost of the determination. The results show that comparable results to the standard method for concentration of 50-500 mg/l could be obtained using a...

R. F. Wilson

1977-01-01

141

Titania-supported iron oxide as oxygen carrier for chemical-looping combustion of methane  

Microsoft Academic Search

Chemical-looping combustion is a two-stage process proposed as an alternative for the combustion of carbonaceous materials, such as natural gas or coal gas, for almost complete CO2 capture. In the reduction stage, the structural oxygen contained in the lattice of a reducible inorganic oxide, is used for combustion of the carbonaceous material. In the regeneration stage the oxygen carrier, found

Beatríz M. Corbella; José María Palacios

2007-01-01

142

A mechanistic investigation of a calcium-based oxygen carrier for chemical looping combustion  

Microsoft Academic Search

Chemical looping combustion (CLC) has been suggested as an energy-efficient method for the capture of carbon dioxide from combustion. It is indirect combustion by the use of an oxygen carrier, which can be used for CO2 capture in power-generating processes. The possibility of CLC using a calcium-based oxygen carrier is investigated in this paper. In the air reactor air is

Laihong Shen; Min Zheng; Jun Xiao; Rui Xiao

2008-01-01

143

Comparison of iron-, nickel-, copper- and manganese-based oxygen carriers for chemical-looping combustion  

Microsoft Academic Search

For combustion with CO2 capture, chemical-looping combustion (CLC) with inherent separation of CO2 is a promising technology. Two interconnected fluidized beds are used as reactors. In the fuel reactor, a gaseous fuel is oxidized by an oxygen carrier, e.g. metal oxide particles, producing carbon dioxide and water. The reduced oxygen carrier is then transported to the air reactor, where it

Paul Cho; Tobias Mattisson; Anders Lyngfelt

2004-01-01

144

ON THE OXYGEN AND NITROGEN CHEMICAL ABUNDANCES AND THE EVOLUTION OF THE 'GREEN PEA' GALAXIES  

Microsoft Academic Search

We have investigated the oxygen and nitrogen chemical abundances in extremely compact star-forming galaxies (SFGs) with redshifts between 0.11 and 0.35, popularly referred to as 'green peas'. Direct and strong-line methods sensitive to the N\\/O ratio applied to their Sloan Digital Sky Survey (SDSS) spectra reveal that these systems are genuine metal-poor galaxies, with mean oxygen abundances 20% solar. At

Ricardo O. Amorin; Enrique Perez-Montero; J. M. Vilchez

2010-01-01

145

Chemical analysis of surface oxygenated moieties of fluorescent carbon nanoparticles  

NASA Astrophysics Data System (ADS)

Water-soluble carbon nanoparticles were prepared by refluxing natural gas soot in concentrated nitric acid. The surface of the resulting nanoparticles was found to be decorated with a variety of oxygenated species, as suggested by spectroscopic measurements. Back potentiometric titration of the nanoparticles was employed to quantify the coverage of carboxylic, lactonic, and phenolic moieties on the particle surface by taking advantage of their vast difference of acidity (pKa). The results were largely consistent with those reported in previous studies with other carbonaceous (nano)materials. Additionally, the presence of ortho- and para-quinone moieties on the nanoparticle surface was confirmed by selective labelling with o-phenylenediamine, as manifested in X-ray photoelectron spectroscopy, photoluminescence, and electrochemical measurements. The results further supported the arguments that the surface functional moieties that were analogous to 9,10-phenanthrenequinone were responsible for the unique photoluminescence of the nanoparticles and the emission might be regulated by surface charge state, as facilitated by the conjugated graphitic core matrix.

Huang, Jie; Deming, Christopher P.; Song, Yang; Kang, Xiongwu; Zhou, Zhi-You; Chen, Shaowei

2012-01-01

146

Computational fluid dynamics methodologies for simulation of chemical oxygen-iodine laser flowfields  

Microsoft Academic Search

Simulation of chemical lasers such as the chemical oxygen-iodine laser (COIL) is of timely interest due to the recent acceleration of the airborne laser military research program and ongoing commercial development programs. As a part of these efforts, a 3-D COIL simulation model was developed based on the Computational Fluid Dynamics (CFD) code GASP which solves the conservative, finite-volume formulation

Timothy John Madden

1997-01-01

147

Carbon deposition characteristics and regenerative ability of oxygen carrier particles for chemical-looping combustion  

Microsoft Academic Search

For gaseous fuel combustion with inherent CO2 capture and low NOx emission, chemical-looping combustion (CLC) may yield great advantages for the savings of energy to CO2 separation and suppressing the effect on the environment. In a chemical-looping combustor, fuel is oxidized by metal oxide\\u000a medium (oxygen carrier particle) in a reduction reactor. Reduced particles are transported to the oxidation reactor

Ho-Jung Ryu; Nam-Yun Lim; Dal-Hee Bae; Gyoung-Tae Jin

2003-01-01

148

Use of coal as fuel for chemical-looping combustion with Ni-based oxygen carrier  

Microsoft Academic Search

Chemical-looping combustion is an indirect combustion technology with inherent separation of the greenhouse gas CO. The feasibility of using NiO as an oxygen carrier during chemical-looping combustion of coal has been investigated experimentally at 800-960°C in the present work. The experiments were carried out in a fluidized bed, where the steam acted as the gasification-fluidization medium. Coal gasification and the

Zhengping Gao; Laihong Shen; Jun Xiao; Cuijuan Qing; Qilei Song

2008-01-01

149

Reactive oxygen species-induced DNA damage and its modification: A chemical investigation  

Microsoft Academic Search

The main purpose of this study was to determine whether well-known reactive oxygen species (ROS)-generating agents can induce DNA damage in a simple chemical system with or without Fenton reaction components (iron and reducing agents), and to explore whether antioxidants which normally exist in the cellular environment can modify such damage, i.e. to determine chemical reactions of relevance to biological

Tian-Wei Yu; Diana Anderson

1997-01-01

150

Modeling of high-pressure O2(1^) generators for chemical oxygen-iodine lasers  

Microsoft Academic Search

A theoretical model is developed for chemical generators producing O2(1(Delta) ) at high pressure. Such generators are especially important for supersonic chemical oxygen-iodine lasers. The model treats different types of generators, e.g., bubble column, film, aerosol, and jet generators. The main factor affecting the O2(1(Delta) ) yield under high pressure is liquid-phase quenching enhanced by depletion of HO2- ions near

B. D. Barmashenko; Salman Rosenwaks

1993-01-01

151

A sensitive ferricyanide-mediated biochemical oxygen demand assay for analysis of wastewater treatment plant influents and treated effluents.  

PubMed

Representative and fast monitoring of wastewater influent and effluent biochemical oxygen demand (BOD) is an elusive goal for the wastewater industry and regulatory bodies alike. The present study describes a suitable assay, which incorporates activated sludge as the biocatalyst and ferricyanide as the terminal electron acceptor for respiration. A number of different sludges and sludge treatments were investigated, primarily to improve the sensitivity of the assay. A limit of detection (LOD) (2.1 mg BOD? L?¹) very similar to that of the standard 5-day BOD? method was achieved in 4 h using raw influent sludge that had been cultured overnight as the biocatalyst. Reducing the microbial concentration was the most effective means to improve sensitivity and reduce the contribution of the sludge's endogenous respiration to total ferricyanide-mediated (FM) respiration. A strong and highly significant relationship was found (n = 33; R = 0.96; p < 0.001; slope = 0.94) between BOD? and FM-BOD equivalent values for a diverse range of samples including wastewater treatment plant (WWTP) influent and treated effluent, as well as several grey water samples. The activated sludge FM-BOD assay presented here is an exceptional surrogate method to the standard BOD? assay, providing representative, same-day BOD analysis of WWTP samples with a comparable detection limit, a 4-fold greater analytical range and much faster analysis time. The industry appeal of such an assay is tremendous given that ~90% of all BOD? analysis is dedicated to measurement of WWTP samples, for which this assay is specifically designed. PMID:23200506

Jordan, Mark A; Welsh, David T; John, Richard; Catterall, Kylie; Teasdale, Peter R

2012-11-14

152

Solvent Effects on Oxygen-17 Chemical Shifts in Methyl Formate: Linear Solvation Shift Relationships  

NASA Astrophysics Data System (ADS)

A multiple linear regression analysis has been carried out using the Kamlet-Abboud-Taft solvatochromic parameters in order to quantify the solvent effects on the 17O chemical shifts of methyl formate (MF). The influence of the solvents upon the carbonyl oxygen chemical shifts is smaller for MF than for N-methylformamide (NMF). The influence (in parts per million) of the solvent polarity-polarizability reduces from -21.9?* in amides to -9.6?* in MF. The influence of the solvent hydrogen-bond-donor acidities reduces from -42.0? in formamides to -16.9? in MF. The solvent effects upon the dicoordinated oxygen chemical shifts of MF are smaller in magnitude and opposite in direction, i.e., 4.8?* and 2.6?, than those for the carbonyl oxygen. 17O hydration shifts have been calculated for the NMF + (H2O)6 and MF + (H2O)5 complexes by the ab initio GIAO method at the 6-311 + G** level. The hydration shifts calculated for the carbonyl oxygens of NMF and MF and for the dicoordinated oxygen of MF, -102.4, -64.7, and 17.6 ppm, respectively, show the same trend as the corresponding empirical hydration shifts, -101.7, -42.0, and 14.2 ppm.

de Kowalewski, Dora G.; Kowalewski, Valdemar J.; Contreras, Ruben H.; Díez, Ernesto; Casanueva, Jorge; San Fabián, Jesús; Esteban, Angel L.; Galache, Maria P.

2001-01-01

153

Test bed for a high throughput supersonic chemical oxygen - iodine laser  

SciTech Connect

The paper reports the development of a test bed for a chemical oxygen - iodine laser based on a high throughput jet flow singlet oxygen generator (JSOG). The system provides vertical singlet oxygen extraction followed by horizontal orientation of subsequent subsystems. This design enables the study of flow complexities and engineering aspects of a distributed weight system as an input for mobile and other platform-mounted systems developed for large scale power levels. The system under consideration is modular and consists of twin SOGs, plenum and supersonic nozzle modules, with the active medium produced in the laser cavity. The maximal chlorine flow rate for the laser is {approx}1.5 mole s{sup -1} achieving a typical chemical efficiency of about 18%. (lasers)

Singhal, Gaurav; Mainuddin; Rajesh, R; Varshney, A K; Dohare, R K; Kumar, Sanjeev; Singh, V K; Kumar, Ashwani; Verma, Avinash C; Arora, B S; Chaturvedi, M K; Tyagi, R K; Dawar, A L

2011-05-31

154

COIL--Chemical Oxygen Iodine Laser: advances in development and applications  

Microsoft Academic Search

Advantageous features of Chemical Oxygen-Iodine Laser (COIL) for laser technologies have increased considerably activities of international COIL communities during past ten years. They have been focused on the advanced concepts of hardware designs of the COIL subsystems, and testing and scaling-up of existing laser facilities. Prospective special applications of COIL technology, both civil and military, have received a significant attention

Jarmila Kodymova

2005-01-01

155

Cutting performance of a chemical oxygen-iodine laser on aerospace and industrial materials  

Microsoft Academic Search

A chemical oxygen-iodine laser (COIL) was used for cutting aluminum, titanium, inconel and copper plates. The laser was operated with a stable resonator having an intracavity aperture to produce a circular COIL beam with very few transverse modes. The multimode focal spot diameter was calculated to be 0.24 mm. The new aluminum cut was of particularly high kerf edge quality.

William P. Latham; Kip R. Kendrick; James A. Rothenflue; Aravinda Kar; David L. Carroll

2000-01-01

156

Development of Cu-based oxygen carriers for chemical-looping combustion  

Microsoft Academic Search

In a chemical-looping combustion (CLC) process, gas (natural gas, syngas, etc.) is burnt in two reactors. In the first one, a metallic oxide that is used as oxygen source is reduced by the feeding gas to a lower oxidation state, being CO2 and steam the reaction products. In the second reactor, the reduced solid is regenerated with air to the

Luis F de Diego; Francisco Garc??a-Labiano; Juan Adánez; Pilar Gayán; Alberto Abad; Beatriz M Corbella; Jose Mar??a Palacios

2004-01-01

157

Chemical oxygen-iodine laser for high-speed cutting of thick stainless steel  

Microsoft Academic Search

A high power chemical oxygen-iodine laser (COIL) at the Air Force's Phillips Laboratory was evaluated to determine its cutting capability in thick section stainless steel. The results of this experiment were used to validate a new model that describes the effects of using rectangular- shaped beams for thick section materials processing. That model, while derived in a way similar to

Joseph E. Scott; James A. Rothenflue; William P. Latham; Aravinda Kar

1996-01-01

158

Comparison of nickel- and iron-based oxygen carriers in chemical looping combustion for CO 2 capture in power generation  

Microsoft Academic Search

In chemical looping combustion (CLC), a solid oxygen carrier circulates between two fluidised bed reactors and transports oxygen from the combustion air to the fuel; thus, the fuel is not mixed with air and an inherent CO2 separation occurs. In this paper, CLC is integrated in a natural gas fired combined cycle (NGCC). In this system, nickel- and iron-based oxygen

Jens Wolf; Marie Anheden; Jinyue Yan

2005-01-01

159

Chemical oxygen-iodine laser with atomic iodine generated in a separate reactor  

NASA Astrophysics Data System (ADS)

The chemical oxygen-iodine laser (COIL) with a chemical method of atomic iodine generation was studied. Two methods of atomic iodine generation were proposed and developed. They are based on fast reactions of gaseous hydrogen iodide with chemically produced chlorine or fluorine atoms. Atomic iodine formation via Cl atoms we studied earlier by mixing of reaction gases directly in the primary O2(1?g) flow in COIL. A revealed oxidation of HI by singlet oxygen and the O2(1?g) quenching by some reaction product, however, reduced the attainable laser gain. This problem could be avoided by atomic iodine generation in separate reactors with following injection of atomic iodine into the primary O2(1?g) flow. Gain measurements using this arrangement are presented in this paper. New experimental results on atomic iodine production via F atoms are also summarized. Using of reactive gases commercially available in pressure cylinders is the main advantage of this method.

Špalek, Otomar; Jirásek, Vít; ?enský, Miroslav; Kodymova, Jarmila; Pickova, Irena; Jakubec, Ivo

2006-05-01

160

Absorption-based highly sensitive and reproducible biochemical oxygen demand measurement method for seawater using salt-tolerant yeast Saccharomyces cerevisiae ARIF KD-003  

Microsoft Academic Search

Salt-tolerant yeast Saccharomyces cerevisiae ARIF KD-003 was applied to highly sensitive and reproducible absorbance-based biochemical oxygen demand (BODAB-ScII) measurement for seawater. In the previous work, we have studied the BODAB-ScI method using normal Baker's yeast S. cerevisiae, and the excellent feature of the Baker's yeast as uniformly sustainable in solution could successfully be utilized. However, the BODAB-ScI responses were disappeared

Hideaki Nakamura; Yotaro Mogi; Hisashi Hattori; Yutaka Kita; Daisuke Hattori; Aki Yoshimura; Isao Karube

2008-01-01

161

Limb Blood Flow and Vascular Conductance Are Reduced With Age in Healthy Humans Relation to Elevations in Sympathetic Nerve Activity and Declines in Oxygen Demand  

Microsoft Academic Search

Background—We tested the hypothesis that basal (resting) limb blood flow and vascular conductance are reduced with age in adult humans and that these changes are related to elevations in sympathetic vasoconstrictor nerve activity and reductions in limb oxygen demand. Methods and Results—Sixteen young (28 61 years; mean6SEM) and 15 older (6361 years) healthy normotensive adult men were studied. Diastolic blood

Frank A. Dinenno; Pamela P. Jones; Douglas R. Seals; Hirofumi Tanaka

162

Parametric study of an efficient supersonic chemical oxygen-iodine laser\\/jet generator system operating without buffer gas  

Microsoft Academic Search

A detailed experimental study of an efficient supersonic chemical oxygen-iodine laser is presented. The laser is energized by a jet-type singlet oxygen generator, operated without primary buffer gas and applies simple nozzle geometry and transonic mixing of iodine and oxygen. Output power of 190 W with chemical efficiency of 18% was obtained in a 5-cm gain length for Cl2 flow

D. Furman; B. D. Barmashenko; S. Rosenwaks

1998-01-01

163

Use of coal as fuel for chemical-looping combustion with Ni-based oxygen carrier  

SciTech Connect

Chemical-looping combustion is an indirect combustion technology with inherent separation of the greenhouse gas CO{sub 2}. The feasibility of using NiO as an oxygen carrier during chemical-looping combustion of coal has been investigated experimentally at 800-960{degree}C in the present work. The experiments were carried out in a fluidized bed, where the steam acted as the gasification-fluidization medium. Coal gasification and the reaction of oxygen carrier with the water gas take place simultaneously in the reactor. The oxygen carrier particles exhibit high reactivity above 900{degree}C, and the dry basis concentration of CO{sub 2} in the exit gas of the reactor is nearly 95%. The flue gas composition as a function of the reactor temperature and cyclic reduction number is discussed. At 800-960{degree}C, the dry basis concentration of CO{sub 2} in the flue gas presents a monotonously increasing trend, whereas the dry basis concentration of CO, H{sub 2}, and CH{sub 4} decreases monotonously. The concentrations of CO{sub 2}, CO, H{sub 2}, and CH{sub 4} in the flue gas as a function of cyclic reduction number present a para-curve characteristic at 900{degree}C. With the increase of cyclic reduction number, the dry basis concentration of CO{sub 2} decreases remarkably, while the dry basis concentrations of CO, H{sub 2}, and CH{sub 4} increase rapidly. Moreover, the peak value of H{sub 2} concentration is less than that of CO. The performance of the NiO-based oxygen carriers was also evaluated using an X-ray diffractometer and a scanning electron microscope to characterize the solid residues of oxygen carrier. The results indicate that NiO is one of the suitable oxygen carriers for chemical-looping combustion of coal.

Gao, Z.P.; Shen, L.H.; Xiao, J.; Qing, C.J.; Song, Q.L. [Southeast University, Nanjing (China). Thermoenergy Engineering Research Institute

2008-12-15

164

Calculation of the mixing chamber of an ejector chemical oxygen - iodine laser  

SciTech Connect

Gas parameters are calculated at the outlet of the mixing chamber of an ejector chemical oxygen-iodine laser with a nozzle unit consisting of nozzles of three types, which provides a total pressure of the active medium that substantially exceeds a pressure in the generator of singlet oxygen. This technique of forming the laser active medium substantially facilitates the ejection of the exhaust gas to the atmosphere by using a diffuser and single-stage vacuum systems based on water circulating pumps. (lasers, active media)

Zagidullin, M V; Nikolaev, V D [Samara Branch of the P.N. Lebedev Physics Institute, Russian Academy of Sciences, Samara (Russian Federation)

2001-06-30

165

Effect of pressure on the behavior of copper-, iron-, and nickel-based oxygen carriers for chemical-looping combustion  

SciTech Connect

This work analyzes the main characteristics related to the chemical looping combustion (CLC) process necessary to use the syngas obtained in an integrated gasification combined cycle (IGCC) power plant. The kinetics of reduction with H{sub 2} and CO and oxidation with O{sub 2} of three high-reactivity oxygen carriers used in the CLC system have been determined in a thermogravimetric analyzer at atmospheric pressure. The iron- and nickel-based oxygen carriers were prepared by freeze-granulation, and the copper-based oxygen carrier was prepared by impregnation. The changing grain size model (CGSM) was used for the kinetic determination, assuming spherical grains for the freeze-granulated particles containing iron and nickel and a platelike geometry for the reacting surface of the copper-based impregnated particles. The dependence of the reaction rates on temperature was low, with the activation energy values varying from 14 to 33 kJ mol{sup -1} for the reduction and 7 to 15 kJ mol{sup -1} for the oxidation. The reaction order depended on the reacting gas and oxygen carrier, with values ranging from 0.25 to 1. However, an increase in the operating pressure for the IGCC + CLC system increases the thermal efficiency of the process, and the CO{sub 2} is recovered as a high pressure gas, decreasing the energy demand for further compression. The effect of pressure on the behavior of the oxygen carriers has been analyzed in a pressurized thermogravimetric analyzer at 1073 K and pressures up to 30 atm. It has been found that an increase in total pressure has a negative effect on the reaction rates of all the oxygen carriers. Moreover, the use of the CGSM with the kinetic parameters obtained at atmospheric pressure predicted higher reaction rates than those experimentally obtained at higher pressures, and therefore, the kinetic parameters necessary to design pressurized CLC plants must be determined at the operating pressure. 34 refs., 8 figs., 2 tabs.

Francisco Garcia-Labiano; Juan Adanez; Luis F. de Diego; Pilar Gayan; Alberto Abad [Instituto de Carboquimica (CSIC), Zaragoza (Spain). Department of Energy and Environment

2006-02-01

166

Use of basic deuterium peroxide in the chemical oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

The chemical oxygen-iodine laser (COIL) uses a reaction of gaseous chorine and aqueous solution of basic oxygen peroxide (BHP) to produce oxygen singlet delta molecules, O2(1(Delta) ). Quenching of O2(1(Delta) ) during its extraction from the BHP solution and quenching of excited atomic iodine I* by water vapor from the O2(1(Delta) ) production process are well-known parasitic effects in COIL. This paper shows that both of these effects can be significantly reduced by replacing the hydrogen 1H1 isotope atoms in BHP by the 1H2 isotope atoms. In addition to restoring laser power lost to parasitic quenching, use of basic deuterium peroxide (BDP) rather than BHP is expected to allow generation of O2(1(Delta) ) at elevated temperature. This approach promises to save refrigerant, reduce the risk of BDP freezing, and delay precipitation of salt form BDP solution. Methods for producing BDP are outlined.

Vetrovec, John; Yang, Tien T.; Copeland, Drew A.

2000-05-01

167

Real-Time Molecular Monitoring of Chemical Environment in ObligateAnaerobes during Oxygen Adaptive Response  

SciTech Connect

Determining the transient chemical properties of the intracellular environment canelucidate the paths through which a biological system adapts to changes in its environment, for example, the mechanisms which enable some obligate anaerobic bacteria to survive a sudden exposure to oxygen. Here we used high-resolution Fourier Transform Infrared (FTIR) spectromicroscopy to continuously follow cellular chemistry within living obligate anaerobes by monitoring hydrogen bonding in their cellular water. We observed a sequence of wellorchestrated molecular events that correspond to changes in cellular processes in those cells that survive, but only accumulation of radicals in those that do not. We thereby can interpret the adaptive response in terms of transient intracellular chemistry and link it to oxygen stress and survival. This ability to monitor chemical changes at the molecular level can yield important insights into a wide range of adaptive responses.

Holman, Hoi-Ying N.; Wozei, Eleanor; Lin, Zhang; Comolli, Luis R.; Ball, David. A.; Borglin, Sharon; Fields, Matthew W.; Hazen, Terry C.; Downing, Kenneth H.

2009-02-25

168

A mechanistic investigation of a calcium-based oxygen carrier for chemical looping combustion  

SciTech Connect

Chemical looping combustion (CLC) has been suggested as an energy-efficient method for the capture of carbon dioxide from combustion. It is indirect combustion by the use of an oxygen carrier, which can be used for CO{sub 2} capture in power-generating processes. The possibility of CLC using a calcium-based oxygen carrier is investigated in this paper. In the air reactor air is supplied to oxidize CaS to CaSO{sub 4}, where oxygen is transferred from air to the oxygen carrier; the reduction of CaSO{sub 4} to CaS takes place in the fuel reactor. The exit gas from the fuel reactor is CO{sub 2} and H{sub 2}O. After condensation of water, almost pure CO{sub 2} could be obtained. The thermodynamic and kinetic problem of the reduction reactions of CaSO{sub 4} with CO and H{sub 2} and the oxidization reactions of CaS with O{sub 2} is discussed in the paper to investigate the technique possibility. To prevent SO{sub 2} release from the process of chemical looping combustion using a calcium-based oxygen carrier, thermochemical CaSO{sub 4} reduction and CaS oxidation are discussed. Thermal simulation experiments are carried out using a thermogravimetric analyzer (TGA). The properties of the products are characterized by Fourier transform infrared (FT-IR) spectroscopy and X-ray diffractometry (XRD), and the optimal reaction parameters are evaluated. The effects of reaction temperature, reductive gas mixture, and oxygen partial pressure on the composition of flue gas are discussed. The suitable temperature of the air reactor is between 1050 and 1150 C and the optimal temperature of the fuel reactor between 900 and 950 C. (author)

Shen, Laihong; Zheng, Min; Xiao, Jun; Xiao, Rui [Key Laboratory of Clean Coal Power Generation and Combustion Technology of Ministry of Education, Southeast University, Nanjing 210096 (China)

2008-08-15

169

Natural minerals as oxygen carriers for chemical looping combustion in a dual circulating fluidized bed system  

Microsoft Academic Search

A first experimental campaign has been conducted at a 120 kW fuel power dual circulating fluidized bed installation for chemical looping combustion of gaseous fuels. In these test runs natural ilmenite (FeTiO3) has been used as oxygen carrier material. The plant consists of two interconnected circulating fluidized bed reactors (stainless steel construction, inner diameter: 0.15 m, height: air reactor 4.1

Tobias Pröll; Karl Mayer; Johannes Bolhàr-Nordenkampf; Philipp Kolbitsch; Tobias Mattisson; Anders Lyngfelt; Hermann Hofbauer

2009-01-01

170

The use of NiO as an oxygen carrier in chemical-looping combustion  

Microsoft Academic Search

The feasibility of using NiO as an oxygen carrier during chemical-looping combustion has been investigated. A thermodynamic analysis with CH4 as fuel showed that the yield of CH4 to CO2 and H2O was between 97.7 and 99.8% in the temperature range 700–1200°C, with the yield decreasing as the temperature increases. Carbon deposition is not expected as long as sufficient metal

Tobias Mattisson; Marcus Johansson; Anders Lyngfelt

2006-01-01

171

Oxygen carrier development for chemical looping combustion of coal derived synthesis gas  

Microsoft Academic Search

In the present work, NETL researchers have studied chemical looping combustion (CLC) with an oxygen carrier NiO\\/bentonite (60 wt.% NiO) for the IGCC systems utilizing simulated synthesis gas. Multi cycle CLC was conducted with NiO\\/Bentonite in TGA at atmospheric pressure and in a high pressure reactor in a temperature range between 700-900°C. Global reaction rates of reduction and oxidation as

R. V. Siriwardane; K. Chaudhari; A. N. Zinn; T. Simonyi; Clark Robinson; J. A. Poston

2006-01-01

172

Chemical-looping combustion of coal-derived synthesis gas over copper oxide oxygen carriers  

Microsoft Academic Search

CuO\\/bentonite and CuO-BHA nanocomposites were studied as oxygen carriers in chemical-looping;\\u000acombustion (CLC) of simulated synthesis gas. Global reaction rates of reduction and oxidation, as the function;\\u000aof reaction conversion, were calculated from 10-cycle oxidation\\/reduction tests utilizing thermogravimetric;\\u000aanalysis at atmospheric pressure between 700 and 900 °C. It was found that the reduction reactions are always;\\u000afaster than oxidation reactions;

Hanjing Tian; Karuna Chaudhari; Thomas Simonyi; James Poston; Tengfei Liu; Tom Sanders; Go?tz Veser; Ranjani Siriwardane

2008-01-01

173

Performance and Apparent Redox Kinetic of a Cu-Based Oxygen Carrier for Chemical Looping Oxygen Production  

NASA Astrophysics Data System (ADS)

The reactivity of Cu-based oxygen carrier prepared by mechanical mixing for producing oxygen was investigated in a thermogravimetric analyzer. The results show that the oxygen carrier has excellent stability during reduction-oxidation cycles. This oxygen carrier showed a maximum oxygen transport capacity of 0.059 g/g during cycle experiments and the time for one cycle is less than 16 min. Phases and surface morphology of oxygen carriers were measured by X-ray diffraction and scanning electron microscope before and after experiments. The phases of reduced oxygen carrier are only Cu2O and TiO2 and of fresh or oxidized samples are only CuO and TiO2. These reveal that the oxygen carrier is stable using the preparation process and under the operation conditions. SEM images show that the fresh and reacted oxygen carrier particles did not appear to disintegrate after 23 cycles.

Wang, Kun; Yu, Qingbo; Xie, Huaqing; Qin, Qin

2013-04-01

174

Development of micellar reactive oxygen species assay for photosafety evaluation of poorly water-soluble chemicals.  

PubMed

A reactive oxygen species (ROS) assay was previously developed for photosafety assessment; however, the phototoxic potential of some chemicals cannot be evaluated because of their limited aqueous solubility. The present study was undertaken to develop a new micellar ROS (mROS) assay system for poorly water-soluble chemicals using a micellar solution of 0.5% (v/v) Tween 20 for solubility enhancement. In repeated mROS assay, intra- and inter-day precisions (coefficient of variation) were found to be below 11%, and the Z'-factors for singlet oxygen and superoxide suggested a large separation band between positive and negative standards. The ROS and mROS assays were applied to 65 phototoxins and 18 non-phototoxic compounds for comparative purposes. Of all 83 chemicals, 25 were unevaluable in the ROS assay due to poor solubility, but only 2 were in the mROS assay. Upon mROS assay on these model chemicals, the individual specificity was 76.5%, and the positive and negative predictivities were found to be 93.9% and 86.7%, respectively. The mROS assay provided 2 false negative predictions, although negative predictivity for the ROS assay was found to be 100%. Considering the pros and cons of these assays, strategic combined use of the ROS and mROS assays might be efficacious for reliable photosafety assessment with high applicability and predictivity. PMID:23727251

Seto, Yoshiki; Kato, Masashi; Yamada, Shizuo; Onoue, Satomi

2013-05-30

175

Innovative technology to meet the demands of the white biotechnology revolution of chemical production  

Microsoft Academic Search

The rapid introduction of bio-production methods in areas where production methods based on fossil fuel raw materials have been dominant for half a century is documented in policy papers by large political organizations as well as in the media.The present review seeks to describe the means by which a technological revolution termed “white biotechnology” for production of commodity chemicals has

John Villadsen

2007-01-01

176

Reverse Engineering of Oxygen Transport in the Lung: Adaptation to Changing Demands and Resources through Space-Filling Networks  

Microsoft Academic Search

The space-filling fractal network in the human lung creates a remarkable distribution system for gas exchange. Landmark studies have illuminated how the fractal network guarantees minimum energy dissipation, slows air down with minimum hardware, maximizes the gas- exchange surface area, and creates respiratory flexibility between rest and exercise. In this paper, we investigate how the fractal architecture affects oxygen transport

Chen Hou; Stefan Gheorghiu; Virginia H. Huxley; Peter Pfeifer

2010-01-01

177

How does the character of oxygen demand control the structure of hypoxia on the Texas–Louisiana continental shelf?  

Microsoft Academic Search

A realistic hydrodynamic model of the Texas–Louisiana shelf is configured with various simple oxygen respiration models to isolate the effects of stratification and circulation on the formation and maintenance of hypoxia. Biological activity is parameterized through various forms of respiration rather than using a complex biogeochemical model. The model domain covers the region that has historically been observed to be

Robert D. Hetland; Steven F. DiMarco

2008-01-01

178

Influence of the organic matter composition on benthic oxygen demand in the Rhône River prodelta (NW Mediterranean Sea)  

NASA Astrophysics Data System (ADS)

Measurements of diffusive (DOU) and total (TOU) sediment oxygen uptakes, oxygen penetration depth, porosity, OC, TN, carbohydrate, lipid, amino acid, chlorophyll a and pheophytin a concentrations were assessed in surface sediments at 9 stations located in the Rhône River prodelta and the adjacent continental shelf during April 2007 (a period characterized by low flow and discharge regimes). Our results show that sedimentary organics in the Rhône River prodelta were mainly fueled by a single source of OM, namely continental inputs. Those inputs were relatively labile and decreased following an inshore-offshore gradient. The descriptors of sedimentary organics mostly resulted from dilution and degradation processes affecting OM during its transfer from the mouth of the Rhône River. TOU/DOU ratios were close to one, with a slight increase at offshore stations. This is coherent with the limitation of bioirrigation in response to organic enrichment. DOU correlated best with bulk quantitative descriptors of sedimentary organics, which probably resulted from the overall correlation between all biochemical descriptors linked with the predominance of a single source of organic matter in the whole studied area. Nevertheless, an influence of Chl a and Pheo a contents on oxygen consumptions, possibly due to freshwater or/and marine primary production, is not to be excluded. These small fractions (<0.08‰ to total OM) could then be responsible for the oxygen consumption, even if not visible in classical measurements as ?13C or C/N.

Pastor, Lucie; Deflandre, Bruno; Viollier, Eric; Cathalot, Cécile; Metzger, Edouard; Rabouille, Christophe; Escoubeyrou, Karine; Lloret, Emily; Pruski, Audrey M.; Vétion, Gilles; Desmalades, Martin; Buscail, Roselyne; Grémare, Antoine

2011-06-01

179

Oxygen contaminants affecting on the electronic structures of the carbon nano tubes grown by rapid thermal chemical vapor deposition  

Microsoft Academic Search

Oxygen-related electronic structures of CNTs (carbon nanotubes) grown by rapid thermal chemical vapor deposition (RT-CVD) have been investigated by using partial electron yield near edge X-ray absorption spectroscopy (PEY-NEXAFS) and X-ray photoelectron spectroscopy (XPS). On the CNT surface with increased oxygen resulting from e-beam irradiation under the O2 gas environment, C k-edge NEXAFS spectra showed an increase of the oxygen-related

Kyuwook Ihm; Tai-Hee Kang; Dae Ho Lee; Ki-Jeong Kim; Bongsoo Kim; Ji Hoon Yang; Chong Yun Park

2006-01-01

180

Chemical-looping combustion in a 300 W continuously operating reactor system using a manganese-based oxygen carrier  

Microsoft Academic Search

Chemical-looping combustion (CLC) is a method for the combustion of fuel gas with inherent separation of carbon dioxide. This technique involves the use of two interconnected reactors. A solid oxygen carrier reacts with the oxygen in air in the air reactor and is then transferred to the fuel reactor, where the fuel gas is oxidized to carbon dioxide and water

A. Abad; T. Mattisson; A. Lyngfelt; M. Rydén

2006-01-01

181

Temperature variations in the oxygen carrier particles during their reduction and oxidation in a chemical-looping combustion system  

Microsoft Academic Search

A particle reaction model including mass and heat transfer has been developed to know the temperature variations produced inside the oxygen carrier particles during the cyclic reduction and oxidation reactions taking place in a chemical-looping combustion (CLC) system. The reactions of the different oxygen carriers based on Cu, Co, Fe, Mn, and Ni during the reduction with fuel gas (CH4,

Francisco García-Labiano; Luis F. de Diego; Juan Adánez; Alberto Abad; Pilar Gayán

2005-01-01

182

A pared-down gas-phase kinetics for the chemical oxygen-iodine laser medium  

NASA Astrophysics Data System (ADS)

Kinetic data obtained in the last decade has resulted in revisions of some mechanisms of excitation and deactivation of excited states in the chemical oxygen-iodine laser (COIL) medium. This review considers new kinetic data and presents analyses of the mechanisms of pumping and quenching of electronically and vibrationally excited states in the oxygen-iodine laser media. An effective three-level model of I2 molecule excitation and relaxation has been developed. The calculated effective rate constants for deactivation of I2(X,11 ? ? ? 24) by O2, N2, He and CO2 are presented. A simplified kinetic package for the COIL active medium is recommended. This model consists of a 30-reaction set with 14 species. The results of calculations utilizing simplified model are in good agreement with the experimental data.

Pichugin, S. Yu.; Heaven, M. C.

2013-11-01

183

Syngas chemical looping gasification process: oxygen carrier particle selection and performance  

SciTech Connect

The syngas chemical looping (SCL) process coproduces hydrogen and electricity. The process involves reducing metal oxides with syngas followed by regeneration of reduced metal oxides with steam and air in a cyclic manner. Iron oxide is determined to be a desired oxygen carrier for hydrogen production considering overall properties including oxygen carrying capacity, thermodynamic properties, reaction kinetics, physical strength, melting points, and environmental effects. An iron oxide based particle can maintain good reactivity for more than 100 reduction-oxidation (redox) cycles in a thermogravimetric analyzer (TGA). The particle exhibits a good crushing strength (>20 MPa) and low attrition rate. Fixed bed experiments are carried out which reaffirm its reactivity. More than 99.75% of syngas is converted during the reduction stage. During the regeneration stage, hydrogen with an average purity of 99.8% is produced. 23 refs., 6 figs., 10 tabs.

Fanxing Li; Hyung Ray Kim; Deepak Sridhar; Fei Wang; Liang Zeng; Joseph Chen; L.-S. Fan [Ohio State University, Columbus, OH (United States). William G. Lowrie Department of Chemical and Biomolecular Engineering

2009-08-15

184

Atomic Oxygen Recombination and Chemical Energy Accommodation on Alumina at High Temperature  

SciTech Connect

To develop heat shields for space vehicles, materials must be characterized in simulation conditions close to those in space environments. The most important conditions for simulating the Earth re-entry phase of space vehicles are achieved through the MESOX set-up associating a 6 kW solar radiation concentrator and a 2450 MHz microwave plasma generator. This paper presents some experimental results for the recombination coefficient {gamma} and the chemical energy accommodation coefficient {beta} in the surface-catalyzed oxygen atom recombination based on experiments performed on the MESOX set-up. This set-up allows both the experimental measurements of the recombination coefficient {gamma} using Optical Emission Spectroscopy and the chemical energy accommodation coefficient {beta} using calorimetry according to a defined protocol. Experimental results are presented for three types of alumina in the temperature range 900-2400 K, for 200 Pa total air pressure. These three alumina differ essentially from their content of sintering additives.

Balat-Pichelin, Marianne J.H.; Bedra, L.; Badie, J.-M. [Laboratoire Procedes, Materiaux et Energie Solaire, PROMES-CNRS (ex IMP-CNRS), BP5, 66125 Odeillo, Font-Romeu (France); Boubert, P. [Institut Universitaire des Systemes Thermiques Industriels, IUSTI-CNRS, 5 rue E. Fermi, 13453 Marseille (France)

2005-05-16

185

Food energy supply and demand: a discrepancy between particulate organic flux and sediment community oxygen consumption in the deep ocean  

Microsoft Academic Search

Abstract Sediment,community,oxygen,consumption,(SCOC) and,particulate,organic,carbon,(POC) flux to the benthic,boundary,layer were,concurrently,measured,at five deep-sea stations on a transect across the eastern and central North Pacific at various,times of year. A free vehicle grab respirometer and,Alvin-manipulated,grab respirometer,were,used to measure,SCOC. Paired particle interceptor traps (PITS) were,used,to collect sedimenting,small,POC at 100 and,600 m,above,the bottom. SCOC decreased,across the transect from,the eutrophic,coastal areas off southern,California to the oligotrophic,central Pacific

1987-01-01

186

CARBON COATED (CARBONOUS) CATALYST IN EBULLATED BED REACTOR FOR PRODUCTION OF OXYGENATED CHEMICALS FROM SYNGAS\\/CO2  

Microsoft Academic Search

There are a number of exothermic chemical reactions which might benefit from the temperature control and freedom from catalyst fouling provided by the ebullated bed reactor technology. A particularly promising area is production of oxygenated chemicals, such as alcohols and ethers, from synthesis gas, which can be economically produced from coal or biomass. The ebullated bed operation requires that the

Peizheng Zhou

2000-01-01

187

CARBON COATED (CARBONOUS) CATALYST IN EBULLATED BED REACTOR FOR PRODUCTION OF OXYGENATED CHEMICALS FROM SYNGAS\\/CO2  

Microsoft Academic Search

There are a number of exothermic chemical reactions which might benefit from the temperature control and freedom from catalyst fouling provided by the ebullated bed reactor technology. A particularly promising area is production of oxygenated chemicals, such as alcohols and ethers, from synthesis gas, which can be economically produced from coal or biomass. The ebullated bed operation requires that the

Peizheng Zhou

2001-01-01

188

LASERS: Efficient generation in a chemical oxygen --- iodine laser with a low buffer-gas flow rate  

Microsoft Academic Search

The efficient generation in a chemical oxygen --- iodine laser (COIL) with a low buffer-gas flow rate for Mach numbers M <= 1 is demonstrated. The maximum output power of the COIL was 415 W for a molecular chlorine flow rate of 20 mmol s-1, which corresponds to a chemical efficiency etach =23%. It is shown that the substitution of

V. N. Azyazov; V. S. Safonov; N. I. Ufimtsev

2002-01-01

189

ON THE OXYGEN AND NITROGEN CHEMICAL ABUNDANCES AND THE EVOLUTION OF THE 'GREEN PEA' GALAXIES  

SciTech Connect

We have investigated the oxygen and nitrogen chemical abundances in extremely compact star-forming galaxies (SFGs) with redshifts between {approx}0.11 and 0.35, popularly referred to as 'green peas'. Direct and strong-line methods sensitive to the N/O ratio applied to their Sloan Digital Sky Survey (SDSS) spectra reveal that these systems are genuine metal-poor galaxies, with mean oxygen abundances {approx}20% solar. At a given metallicity these galaxies display systematically large N/O ratios compared to normal galaxies, which can explain the strong difference between our metallicities measurements and previous ones. While their N/O ratios follow the relation with stellar mass of local SFGs in the SDSS, we find that the mass-metallicity relation of the 'green peas' is offset {approx_gt}0.3 dex to lower metallicities. We argue that recent interaction-induced inflow of gas, possibly coupled with a selective metal-rich gas loss, driven by supernova winds, may explain our findings and the known galaxy properties, namely high specific star formation rates, extreme compactness, and disturbed optical morphologies. The 'green pea' galaxy properties seem to be uncommon in the nearby universe, suggesting a short and extreme stage of their evolution. Therefore, these galaxies may allow us to study in great detail many processes, such as starburst activity and chemical enrichment, under physical conditions approaching those in galaxies at higher redshifts.

Amorin, Ricardo O.; Perez-Montero, Enrique; Vilchez, J. M., E-mail: amorin@iaa.e, E-mail: epm@iaa.e, E-mail: jvm@iaa.e [Instituto de Astrofisica de Andalucia (CSIC), Glorieta de la Astronomia S/N, E-18008 Granada (Spain)

2010-06-01

190

Development and performance of Cu-based oxygen carriers for chemical-looping combustion  

SciTech Connect

Chemical-looping combustion (CLC) has the inherent property of separating the product CO{sub 2} from flue gases. Instead of air, it uses an oxygen carrier, usually in the form of a metal oxide, to provide oxygen for combustion. This paper focuses on the development and performance of a suitable Cu-based oxygen carrier for burning solid fuels using CLC. Carriers were made from CuO and Al{sub 2}O{sub 3} (as a support) in three different ways: mechanical mixing, wet impregnation, and co-precipitation. The reactivity of these solids was assessed by measuring their ability to oxidize CO, when in a hot bed of sand fluidized by a mixture of CO and N{sub 2}. After that, the Cu in the carrier was oxidized back to CuO by fluidizing the hot bed with air. These oxygen carriers were tested over many such cycles of reduction and oxidation. This work confirms that supporting CuO on Al{sub 2}O{sub 3} enhances the ability of the resulting particles to withstand mechanical and thermal stresses in a fluidized bed. Also, only co-precipitation produces particles that have a high loading of copper and do not agglomerate at 800-900 C. The performance of co-precipitated particles of CuO/Al{sub 2}O{sub 3} at oxidizing CO to CO{sub 2} was significantly affected by the pH of the solution in which precipitation occurred: a high pH (9.7) gave particles that reacted completely and rapidly. After 18 cycles, such a co-precipitated carrier with 82.5 wt% CuO yielded all its oxygen when oxidizing CO. X-ray analysis showed that when heated, CuO reacted with Al{sub 2}O{sub 3} to form CuAl{sub 2}O{sub 4}, which was fully reducible, so CuO experienced no loss in extent of reaction after forming this mixed oxide. An increase in operating temperature from 800 to 900 C led to the CuO providing slightly less oxygen; this was because a little of the CuO decomposed to Cu{sub 2}O between its reduction and oxidation, when the bed was fluidized by pure N{sub 2}. (author)

Chuang, S.Y.; Dennis, J.S.; Hayhurst, A.N.; Scott, S.A. [Department of Chemical Engineering, University of Cambridge, Pembroke Street, Cambridge, CB2 3RA, England (United Kingdom)

2008-07-15

191

Chemical mechanisms of the toxicological properties of nanomaterials: generation of intracellular reactive oxygen species.  

PubMed

As more and more nanomaterials with novel physicochemical properties or new functions are created and used in different research fields and industrial sectors, the scientific and public concerns about their toxic effects on human health and the environment are also growing quickly. In the past decade, the study of the toxicological properties of nanomaterials/nanoparticles has formed a new research field: nanotoxicology. However, most of the data published relate to toxicological phenomena and there is less understanding of the underlying mechanism for nanomaterial-induced toxicity. Nanomaterial-induced reactive oxygen species (ROS) play a key role in cellular and tissue toxicity. Herein, we classify the pathways for intracellular ROS production by nanomaterials into 1)?the direct generation of ROS through nanomaterial-catalyzed free-radical reactions in cells, and 2)?the indirect generation of ROS through disturbing the inherent biochemical equilibria in cells. We also discuss the chemical mechanisms associated with above pathways of intracellular ROS generation, from the viewpoint of the high reactivity of atoms on the nanosurface. We hope to aid in the understanding of the chemical origin of nanotoxicity to provide new insights for chemical and material scientists for the rational design and creation of safer and greener nanomaterials. PMID:23881693

Yan, Liang; Gu, Zhanjun; Zhao, Yuliang

2013-07-23

192

Investigation of coal fueled chemical looping combustion using Fe 3 O 4 as oxygen carrier: Influence of variables  

Microsoft Academic Search

Chemical-looping combustion (CLC) is a novel combustion technique with inherent CO2 separation. Magnetite (Fe3O4) was selected as the oxygen carrier. Shenhua coal (Inner Mongolia, China), straw coke and natural coke were used as fuels\\u000a for this study. Influences of operation temperatures, coal to Fe3O4 mass ratios, and different kinds of fuels on the reduction characteristics of the oxygen carrier were

Xiaoyan Sun; Wenguo Xiang; Sha Wang; Wendong Tian; Xiang Xu; Yanji Xu; Yunhan Xiao

2010-01-01

193

Reduction kinetics of Cu, Ni, and Fe-based oxygen carriers using syngas (CO + Hâ) for chemical-looping combustion  

Microsoft Academic Search

The reactivity of three Cu-, Fe-, and Ni-based oxygen carriers to be used in a chemical-looping combustion (CLC) system using syngas as fuel has been analyzed. The oxygen carriers exhibited high reactivity during reduction with fuel gases present in syngas (Hâ and CO), with average values in the range 8-30% min⁻¹. No effect of the gas products (HâO, COâ) on

Alberto Abad; Francisco Garcia-Labiano; Luis F. de Diego; Pilar Gayán; Juan Adánez

2007-01-01

194

Hydrogen production by chemical-looping reforming in a circulating fluidized bed reactor using Ni-based oxygen carriers  

Microsoft Academic Search

This work presents the experimental results obtained during auto-thermal chemical-looping reforming (CLR) in a 900 Wth circulating fluidized bed reactor under continuous operation using methane as fuel. Two oxygen carriers based on NiO and supported on ?-Al2O3 and ?-Al2O3 were used during more than 50h of operation with each oxygen carrier. During operation the effect of different operating variables, like

Luis F. de Diego; María Ortiz; Francisco García-Labiano; Juan Adánez; Alberto Abad; Pilar Gayán

2009-01-01

195

Chemical kinetics of radio-frequency driven atmospheric-pressure helium-oxygen plasmas in humid air  

NASA Astrophysics Data System (ADS)

We describe the chemical kinetics of radio-frequency (rf) driven atmospheric-pressure helium-based plasmas in ambient air as determined through a zero-dimensional time-dependent global model. The effects of humid-air admixtures on the plasma-induced chemical reactions and the evolution of species concentrations in the helium-oxygen mixture (He-O2, helium with 5000 ppm admixture of oxygen) are studied for wide air impurity levels of 1-5000 ppm with the relative humidity of 0-100%. Comparisons made with experiments using an rf driven micro-scale atmospheric pressure plasma jet and one-dimensional simulations suggest that the plausible air impurity level in the experiments is not more than hundreds ppm. Effects of the air impurity containing water-humidity on electro-negativity and chemical activity are clarified with particular emphasis on reactive oxygen species.

Murakami, Tomoyuki; Niemi, Kari; Gans, Timo; O'Connell, Deborah; Graham, William

2011-11-01

196

Modelling chemical reactions in dc plasma inside oxygen bubbles in water  

NASA Astrophysics Data System (ADS)

Plasmas generated inside oxygen bubbles in water have been developed for water purification. Zero-dimensional numerical simulations were used to investigate the chemical reactions in plasmas driven by dc voltage. The numerical and experimental results of the concentrations of hydrogen peroxide and ozone in the solution were compared with a discharge current between 1 and 7 mA. Upon increasing the water vapour concentration inside bubbles, we saw from the numerical results that the concentration of hydrogen peroxide increased with discharge current, whereas the concentration of ozone decreased. This finding agreed with the experimental results. With an increase in the discharge current, the heat flux from the plasma to the solution increased, and a large amount of water was probably vaporized into the bubbles.

Takeuchi, N.; Ishii, Y.; Yasuoka, K.

2012-02-01

197

Pulse-periodic chemical oxygen-iodine laser with active medium formation by volumetric electric discharge  

NASA Astrophysics Data System (ADS)

The paper describes a study of pulse-periodic operation of a chemical oxygen-iodine laser. The generator in use was of the jet type with high chlorine utilization degree (>=97%). Atomic iodine was released by dissociating methyl-iodide (CH3I) in volumetric electric discharge. Steady lasing was achieved at a repetition rate up to 30 Hz. The emission energy attained per individual pulse in a train was 1.1 J at a pulse energy repeatability of (3÷5) % and a specific energy extraction from the active medium of 1.7 J/L. The lasing pulse duration depended on the concentration of methyl-iodide and the energy deposited into discharge. The minimal half-height duration of pulses was achieved as 10 ?m at a concentration of atomic iodine in the laser cavity ~1*1015 cm-3.

Velikanov, S. D.; Gorelov, V. G.; Gostev, I. V.; Ireshev, Ye. V.; Kalinovsky, V. V.; Komissarov, I. A.; Konovalov, V. V.; Konovalov, I. V.; Mikhalkin, V. N.; Nikolaev, V. D.; Sevryugin, I. V.; Smirnov, A. V.; Sobolev, R. E.; Shornikov, L. N.

2007-05-01

198

Cutting performance of a chemical oxygen-iodine laser on aerospace and industrial materials  

NASA Astrophysics Data System (ADS)

A chemical oxygen-iodine laser (COIL) was used for cutting aluminum, titanium, inconel and copper plates. The laser was operated with a stable resonator having an intracavity aperture to produce a circular COIL beam with very few transverse modes. The multimode focal spot diameter was calculated to be 0.24 mm. The new aluminum cut was of particularly high kerf edge quality. These COIL cutting data are compared with an existing theoretical laser cutting model. Using thermophysical data for aluminum, titanium,l inconel and copper, this theory agrees very well with the data. To test the versatility of the model, the effects of different assumptions are examined; different assumptions produced very little effect on model predictions at high cutting speeds and a small difference at very slow cutting speeds. Overall, the theoretical model provides good agreement with experiments for a wide variety of metals.

Latham, William P.; Kendrick, Kip R.; Rothenflue, James A.; Kar, Aravinda; Carroll, David L.

2000-01-01

199

Can Galactic Chemical Evolution Explain the Oxygen Isotopic Variations in the Solar System?  

NASA Astrophysics Data System (ADS)

A number of objects in primitive meteorites have oxygen isotopic compositions that place them on a distinct, mass-independent fractionation line with a slope of one on a three-isotope plot. The most popular model for describing how this fractionation arose assumes that CO self-shielding produced 16O-rich CO and 16O-poor H2O, where the H2O subsequently combined with interstellar dust to form relatively 16O-poor solids within the solar nebula. Another model for creating the different reservoirs of 16O-rich gas and 16O-poor solids suggests that these reservoirs were produced by Galactic chemical evolution (GCE) if the solar system dust component was somewhat younger than the gas component and both components were lying on the line of slope one in the O three-isotope plot. We argue that GCE is not the cause of mass-independent fractionation of the oxygen isotopes in the solar system. The GCE scenario is in contradiction with observations of the 18O/17O ratios in nearby molecular clouds and young stellar objects. It is very unlikely for GCE to produce a line of slope one when considering the effect of incomplete mixing of stellar ejecta in the interstellar medium. Furthermore, the assumption that the solar system dust was younger than the gas requires unusual timescales or the existence of an important stardust component that is not theoretically expected to occur nor has been identified to date.

Lugaro, Maria; Liffman, Kurt; Ireland, Trevor R.; Maddison, Sarah T.

2012-11-01

200

A Chemical Kinetic Modeling Study of the Effects of Oxygenated Hydrocarbons on Soot Emissions from Diesel Engines  

SciTech Connect

A detailed chemical kinetic modeling approach is used to examine the phenomenon of suppression of sooting in diesel engines by addition of oxygenated hydrocarbon species to the fuel. This suppression, which has been observed experimentally for a few years, is explained kinetically as a reduction in concentrations of soot precursors present in the hot products of a fuel-rich diesel ignition zone when oxygenates are included. Oxygenates decrease the overall equivalence ratio of the igniting mixture, producing higher ignition temperatures and more radical species to consume more soot precursor species, leading to lower soot production. The kinetic model is also used to show how different oxygenates, ester structures in particular, can have different soot-suppression efficiencies due to differences in molecular structure of the oxygenated species.

Westbrook, C K; Pitz, W J; Curran, H J

2005-11-14

201

Solid waste management of a chemical-looping combustion plant using Cu-based oxygen carriers.  

PubMed

Waste management generated from a Chemical-Looping Combustion (CLC) plant using copper-based materials is analyzed by two ways: the recovery and recycling of the used material and the disposal of the waste. A copper recovery process coupled to the CLC plant is proposed to avoid the loss of active material generated by elutriation from the system. Solid residues obtained from a 10 kWth CLC prototype operated during 100 h with a CuO-Al2O3 oxygen carrier prepared by impregnation were used as raw material in the recovery process. Recovering efficiencies of approximately 80% were obtained in the process, where the final products were an eluate of Cu(NO3)2 and a solid. The eluate was used for preparation of new oxygen carriers by impregnation, which exhibited high reactivity for reduction and oxidation reactions as well as adequate physical and chemical properties to be used in a CLC plant. The proposed recovery process largely decreases the amount of natural resources (Cu and Al203) employed in a CLC power plant as well as the waste generated in the process. To determine the stability of the different solid streams during deposition in a landfill, these were characterized with respect to their leaching behavior according to the European Union normative. The solid residue finally obtained in the CLC plant coupled to the recovery process (composed by Al2O3 and CuAl2O4) can be classified as a stable nonreactive hazardous waste acceptable at landfills for nonhazardous wastes. PMID:17874801

García-Labiano, Francisco; Gayán, Pilar; Adánez, Juan; De Diego, Luis F; Forero, Carmen R

2007-08-15

202

Photocatalytic characteristics of hydro-oxygenated amorphous titanium oxide films prepared using remote plasma enhanced chemical vapor deposition  

NASA Astrophysics Data System (ADS)

The photocatalytic activity and photoconductive characteristics of hydro-oxygenated amorphous titanium oxide (a-TiOx:OH) films prepared using remote plasma enhanced chemical vapor deposition (RPE-CVD) were studied. The a-TiOx:OH films have OH groups, which when exposed to UV irradiation, show high photoconductivity. The photoconductivity is drastically affected by oxygen gas. The results suggest that the recombination states present in the film are non-activated by the OH endings in the dangling bond like the hydrogen endings in hydrogenated amorphous silicon. Oxygen-sensitive photoconductivity is useful for environmental sensor applications.

Hatanaka, Y.; Naito, H.; Itou, C. S.; Kando, M.

2005-05-01

203

Two-dimensional source flow gain model for the chemical oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

A source flow gain model for optical extraction from the chemical oxygen-iodine laser medium is presented. In this model the gas dynamics of the reactive flow through the optical cavity, transverse to the optical axis, is described by the two-dimensional boundary-layer approximation to the full Navier-Stokes equations. The appropriate mass continuity, species, momentum, and energy conservation equations in cylindrical polar coordinates are presented and discussed. The gas kinetics are described by a reduced set of fourteen reactions among nine chemical species and includes pumping of the upper laser level by O2(1(Delta) ), deactivation by water and energy pooling with O2(1(Delta) ), and the Heidner molecular I2 dissociation mechanism. Stimulated emission on the 3 YLD 4 hyperfine transition of atomic iodine is described by a generalized version of the Zagidullian gain model which includes finite hyperfine relaxation of the 2P1/2 and 2P3/2 iodine sublevels, velocity cross-relaxation of the iodine atoms, and allows for incomplete I2 dissociation. The model is illustrated by application to a laboratory-sized device and the effects of the boundary layer upon the gas flow, I2 dissociation, O2(1(Delta) ) fraction, small signal gain, optical extraction, and the medium homogeneity are examined.

Copeland, Drew A.; Yang, Tien T.

1997-05-01

204

Experiments on chemical looping combustion of coal with a NiO based oxygen carrier  

SciTech Connect

A chemical looping combustion process for coal using interconnected fluidized beds with inherent separation of CO{sub 2} is proposed in this paper. The configuration comprises a high velocity fluidized bed as an air reactor, a cyclone, and a spout-fluid bed as a fuel reactor. The high velocity fluidized bed is directly connected to the spout-fluid bed through the cyclone. Gas composition of both fuel reactor and air reactor, carbon content of fly ash in the fuel reactor, carbon conversion efficiency and CO{sub 2} capture efficiency were investigated experimentally. The results showed that coal gasification was the main factor which controlled the contents of CO and CH{sub 4} concentrations in the flue gas of the fuel reactor, carbon conversion efficiency in the process of chemical looping combustion of coal with NiO-based oxygen carrier in the interconnected fluidized beds. Carbon conversion efficiency reached only 92.8% even when the fuel reactor temperature was high up to 970 C. There was an inherent carbon loss in the process of chemical looping combustion of coal in the interconnected fluidized beds. The inherent carbon loss was due to an easy elutriation of fine char particles from the freeboard of the spout-fluid bed, which was inevitable in this kind of fluidized bed reactor. Further improvement of carbon conversion efficiency could be achieved by means of a circulation of fine particles elutriation into the spout-fluid bed or the high velocity fluidized bed. CO{sub 2} capture efficiency reached to its equilibrium of 80% at the fuel reactor temperature of 960 C. The inherent loss of CO{sub 2} capture efficiency was due to bypassing of gases from the fuel reactor to the air reactor, and the product of residual char burnt with air in the air reactor. Further experiments should be performed for a relatively long-time period to investigate the effects of ash and sulfur in coal on the reactivity of nickel-based oxygen carrier in the continuous CLC reactor. (author)

Shen, Laihong; Wu, Jiahua; Xiao, Jun [Thermoenergy Engineering Research Institute, Southeast University, 2 Sipailou, Nanjing 210096 (China)

2009-03-15

205

Oxygen fugacity regime in the upper mantle as a reflection of the chemical differentiation of planetary materials  

Microsoft Academic Search

Oxygen fugacity (fO2) in the Earth’s mantle has a bearing on the problems of the chemical differentiation of the Earth’s materials and formation\\u000a of the chemical and phase state of its shells. This paper addresses some problems concerning changes in the redox state of\\u000a the upper mantle over geologic time and through its depth and the possible influence of fO2

A. A. Kadik

2006-01-01

206

CAN GALACTIC CHEMICAL EVOLUTION EXPLAIN THE OXYGEN ISOTOPIC VARIATIONS IN THE SOLAR SYSTEM?  

SciTech Connect

A number of objects in primitive meteorites have oxygen isotopic compositions that place them on a distinct, mass-independent fractionation line with a slope of one on a three-isotope plot. The most popular model for describing how this fractionation arose assumes that CO self-shielding produced {sup 16}O-rich CO and {sup 16}O-poor H{sub 2}O, where the H{sub 2}O subsequently combined with interstellar dust to form relatively {sup 16}O-poor solids within the solar nebula. Another model for creating the different reservoirs of {sup 16}O-rich gas and {sup 16}O-poor solids suggests that these reservoirs were produced by Galactic chemical evolution (GCE) if the solar system dust component was somewhat younger than the gas component and both components were lying on the line of slope one in the O three-isotope plot. We argue that GCE is not the cause of mass-independent fractionation of the oxygen isotopes in the solar system. The GCE scenario is in contradiction with observations of the {sup 18}O/{sup 17}O ratios in nearby molecular clouds and young stellar objects. It is very unlikely for GCE to produce a line of slope one when considering the effect of incomplete mixing of stellar ejecta in the interstellar medium. Furthermore, the assumption that the solar system dust was younger than the gas requires unusual timescales or the existence of an important stardust component that is not theoretically expected to occur nor has been identified to date.

Lugaro, Maria [Monash Centre for Astrophysics (MoCA), Building 28, Monash University, Clayton, VIC 3800 (Australia); Liffman, Kurt [CSIRO/MSE, P.O. Box 56, Highett, VIC 3190 (Australia); Ireland, Trevor R. [Planetary Science Institute and Research School of Earth Sciences, Australian National University, Canberra, ACT 0200 (Australia); Maddison, Sarah T., E-mail: maria.lugaro@monash.edu [Centre for Astrophysics and Supercomputing, Swinburne University, H39, P.O. Box 218, Hawthorn, VIC 3122 (Australia)

2012-11-01

207

Effect of pressure on the behavior of copper-, iron-, and nickel-based oxygen carriers for chemical-looping combustion  

Microsoft Academic Search

This work analyzes the main characteristics related to the chemical looping combustion (CLC) process necessary to use the syngas obtained in an integrated gasification combined cycle (IGCC) power plant. The kinetics of reduction with Hâ and CO and oxidation with Oâ of three high-reactivity oxygen carriers used in the CLC system have been determined in a thermogravimetric analyzer at atmospheric

Francisco Garcia-Labiano; Juan Adanez; Luis F. de Diego; Pilar Gayan; Alberto Abad

2006-01-01

208

Pressurized chemical-looping combustion of coal with an iron ore-based oxygen carrier  

SciTech Connect

Chemical-looping combustion (CLC) is a new combustion technology with inherent separation of CO{sub 2}. Most of the previous investigations on CLC of solid fuels were conducted under atmospheric pressure. A pressurized CLC combined cycle (PCLC-CC) system is proposed as a promising coal combustion technology with potential higher system efficiency, higher fuel conversion, and lower cost for CO{sub 2} sequestration. In this study pressurized CLC of coal with Companhia Valedo Rio Doce (CVRD) iron ore was investigated in a laboratory fixed bed reactor. CVRD iron ore particles were exposed alternately to reduction by 0.4 g of Chinese Xuzhou bituminous coal gasified with 87.2% steam/N{sub 2} mixture and oxidation with 5% O{sub 2} in N{sub 2} at 970 C. The operating pressure was varied between 0.1 MPa and 0.6 MPa. First, control experiments of steam coal gasification over quartz sand were performed. H{sub 2} and CO{sub 2} are the major components of the gasification products, and the operating pressure influences the gas composition. Higher concentrations of CO{sub 2} and lower fractions of CO, CH{sub 4}, and H{sub 2} during the reduction process with CVRD iron ore was achieved under higher pressures. The effects of pressure on the coal gasification rate in the presence of the oxygen carrier were different for pyrolysis and char gasification. The pressurized condition suppresses the initial coal pyrolysis process while it also enhances coal char gasification and reduction with iron ore in steam, and thus improves the overall reaction rate of CLC. The oxidation rates and variation of oxygen carrier conversion are higher at elevated pressures reflecting higher reduction level in the previous reduction period. Scanning electron microscope and energy-dispersive X-ray spectroscopy (SEM-EDX) analyses show that particles become porous after experiments but maintain structure and size after several cycles. Agglomeration was not observed in this study. An EDX analysis demonstrates that there is very little coal ash deposited on the oxygen carrier particles but no appreciable crystalline phases change as verified by X-ray diffraction (XRD) analysis. Overall, the limited pressurized CLC experiments carried out in the present work suggest that PCLC of coal is promising and further investigations are necessary. (author)

Xiao, Rui; Song, Min; Zhang, Shuai; Shen, Laihong [School of Energy and Environment, Southeast University, Sipailou No. 2, Nanjing 210096 (China); Song, Qilei [School of Energy and Environment, Southeast University, Sipailou No. 2, Nanjing 210096 (China); Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA (United Kingdom); Lu, Zuoji [School of Energy and Environment, Southeast University, Sipailou No. 2, Nanjing 210096 (China); GCL Engineering Limited, Zhujiang No. 1, Nanjing 210008 (China)

2010-06-15

209

Oxygen-induced physical property variation of deposited ZnO films by metal-organic chemical vapor deposition  

NASA Astrophysics Data System (ADS)

High-quality ZnO thin films were deposited on 6Hsbnd SiC substrates using metal-organic chemical vapor deposition system. The physical properties of as-prepared ZnO layers under various oxygen flow rate were thoroughly studied. An increase in the O/Zn ratio yielded a decrease in growth rate. The experimental results also indicated that the size of ZnO nanoparticles, lattice constant and compressive stress inside the films displayed a regular variety as a function of O2-flow rate. In addition, with increase of oxygen discharge, the position of deep-level emission in photoluminescence spectra demonstrated a significant shift, with transformation from oxygen vacancy to zinc vacancy. The qualitative calculation from X-ray photoelectron spectroscopy data showed that higher O2-flow rate was able to promote Osbnd Zn bond formation and reduce the number of oxygen vacancies.

Shi, Zhifeng; Zhang, Shikai; Wu, Bin; Cai, Xupu; Zhang, Jinxiang; Yin, Wei; Wang, Hui; Wang, Jin; Xia, Xiaochuan; Dong, Xin; Zhang, Baolin; Du, Guotong

2012-09-01

210

Construction of oxygen and chemical concentration gradients in a single microfluidic device for studying tumor cell-drug interactions in a dynamic hypoxia microenvironment.  

PubMed

Recent microfluidic advancements in oxygen gradients have greatly promoted controllable oxygen-sensitive cellular investigations at microscale resolution. However, multi-gradient integration in a single microfluidic device for tissue-mimicking cell investigation is not yet well established. In this study, we describe a method that can generate oxygen and chemical concentration gradients in a single microfluidic device via the formation of an oxygen gradient in a chamber and a chemical concentration gradient between adjacent chambers. The oxygen gradient dynamics were systematically investigated, and were quantitatively controlled using simple exchange between the aerial oxygen and the oxygen-free conditions in the gas-permeable polydimethylsiloxane channel. Meanwhile, the chemical gradient dynamics was generated using a special channel-branched device. For potential medical applications of the established oxygen and chemical concentration gradients, a tumor cell therapy assessment was performed using two antitumor drugs (tirapazamine and bleomycin) and two tumor cell lines (human lung adenocarcinoma A549 cells and human cervical carcinoma HeLa cells). The results of the proof-of-concept experiment indicate the dose-dependent antitumor effect of the drugs and hypoxia-induced cytotoxicity of tirapazamine. We demonstrate that the integration of oxygen and chemical concentration gradients in a single device can be applied to investigating oxygen- and chemical-sensitive cell events, which can also be valuable in the development of multi-gradient generating procedures and specific drug screening. PMID:23254684

Wang, Lei; Liu, Wenming; Wang, Yaolei; Wang, Jian-chun; Tu, Qin; Liu, Rui; Wang, Jinyi

2013-02-21

211

The I2 dissociation mechanisms in the chemical oxygen-iodine laser revisited  

NASA Astrophysics Data System (ADS)

The recently suggested mechanism of I2 dissociation in the chemical oxygen-iodine laser (COIL) [K. Waichman, B. D. Barmashenko, and S. Rosenwaks, J. Appl. Phys. 106, 063108 (2009); and J. Chem. Phys. 133, 084301 (2010)] was largely based on the suggestion of V. N. Azyazov, S. Yu. Pichugin, and M. C. Heaven [J. Chem. Phys. 130, 104306 (2009)] that the vibrational population of O2(a) produced in the chemical generator is high enough to play an essential role in the dissociation. The results of model calculations based on this mechanism agreed very well with measurements of the small signal gain g, I2 dissociation fraction F, and temperature T in the COIL. This mechanism is here revisited, following the recent experiments of M. V. Zagidullin [Quantum Electron. 40, 794 (2010)] where the observed low population of O2(b, v = 1) led to the conclusion that the vibrational population of O2(a) at the outlet of the generator is close to thermal equilibrium value. This value corresponds to a very small probability, ~0.05, of O2(a) energy pooling to the states O2(X,a,b, v > 0). We show that the dissociation mechanism can reproduce the experimentally observed values of g, F, and T in the COIL only if most of the energy released in the processes of O2(a) energy pooling and O2(b) quenching by H2O ends up as vibrational energy of the products, O2(X,a,b), where the vibrational states v = 2 and 3 are significantly populated. We discuss possible reasons for the differences in the suggested vibrational population and explain how these differences can be reconciled.

Waichman, K.; Barmashenko, B. D.; Rosenwaks, S.

2012-06-01

212

A spectrophotometric biochemical oxygen demand determination method using 2,6-dichlorophenolindophenol as the redox color indicator and the eukaryote Saccharomyces cerevisiae.  

PubMed

A method to determine the spectrophotometric biochemical oxygen demand (BOD(sp)) was studied with high sensitivity and reproducibility by employing 2,6-dichlorophenolindophenol (DCIP) as a redox color indicator, the yeast Saccharomyces cerevisiae, and a temperature-controlling system providing a three-consecutive-stir unit. The absorbance of DCIP decreased due to the metabolism of organic substances in aqueous samples by S. cerevisiae. Under optimum conditions, a calibration curve for glucose glutamic acid concentration between 1.1 and 22mg O(2) L(-1) (r=0.988, six points, n=3) was obtained when the incubation mixture was incubated for 10min at 30 degrees C. The reproducibility of the optical responses in the calibration curve was 1.77% (average of relative standard deviations; RSD(av)). Subsequently, the characterization of this method was studied. The optical responses to pure organic substances and the influence of chloride ions, artificial seawater, and heavy metal ions on the sensor response were investigated before use with real samples. Measurements of real samples using river water were performed and compared with those obtained using the BOD(5) method. Finally, stable responses were obtained for 36 days when the yeast cell suspension was stored at 4 degrees C (response reduction, 89%; RSD(av) value for 9 testing days, 8.4%). PMID:17716613

Nakamura, Hideaki; Kobayashi, Shun; Hirata, Yu; Suzuki, Kyota; Mogi, Yotaro; Karube, Isao

2007-06-27

213

Effect of oxygen on filament activity in diamond chemical vapor deposition  

SciTech Connect

Previous studies that have focused on the interactions of CH{sub 4}/H{sub 2} and C{sub 2}H{sub 2}/H{sub 2} mixtures with the hot W filaments used for diamond chemical vapor deposition have been extended in order to determine the effect of oxygen on filament activity. The behavior of W filaments has now been studied up to 2300 {degree}C in mixtures of 3% CH{sub 4}/H{sub 2}, with 0.5, 1.0, and 1.5% O{sub 2}, at a pressure of 25 Torr. The effects of the addition of O{sub 2} on filament resistance, emissivity, and power consumption, as well as on the partial pressures of the gases (CH{sub 4}, C{sub 2}H{sub 2}, O{sub 2}, CO, and H{sub 2}O ) in the reaction chamber, have been determined. The significant improvements in filament activity that are observed are shown to be due to removal of carbon from the filament surface by formation of CO. These results can be understood on the basis of our quasi-equilibrium thermodynamic model for the C--H--O system.

Sommer, M.; Smith, F.W. (Department of Physics, The City College of the City University of New York, New York, New York 10031 (US))

1991-05-01

214

Chemical oxygen-iodine laser (COIL) for the dismantlement of nuclear facilities  

NASA Astrophysics Data System (ADS)

The dismantlement of obsolete nuclear facilities is a major challenge for both the US Department of Energy and nuclear power utilities. Recent demonstrations have shown that lasers can be highly effective for size reduction cutting, especially for the efficient storage and recycling of materials. However, the full benefits of lasers can only be realized with high average power beams that can be conveniently delivered, via fiber optics, to remote and/or confined areas. Industrial lasers that can meet these requirements are not available now or for the foreseeable future. However, a military weapon laser, a Chemical Oxygen Iodine Laser (COIL), which has been demonstrated at over a hundred kilo Watts, could be adapted to meet these needs and enable entirely new industrial applications. An 'industrialized' COIL would enable rapid sectioning of thick and complex structures, such as glove boxes, reactor vessels, and steam generators, accelerating dismantlement schedules and reducing worker hazards. The full advantages of lasers in dismantlement could finally be realized with a portable COIL which is integrated with sophisticated robotics. It could be built and deployed in less than two years, breaking the paradigm of labor-intensive dismantlement operations and cutting processing times and costs dramatically.

Hallada, Marc R.; Seiffert, Stephan L.; Walter, Robert F.; Vetrovec, John

2000-05-01

215

Chemical Oxygen-Iodine Laser Diluted by CO2/N2 Buffer Gases with a Cryosorption Vacuum Pump  

NASA Astrophysics Data System (ADS)

Experiments were carried out on a verti-chemical oxygen-iodine laser (COIL), which was designed for N2 and energized by a square-pipe jet singlet oxygen generator (JSOG). A cryosorption vacuum pump was used as the pressure recovery system for CO2 and N2 buffer gases. The output power with CO2 was 27.3% lower than that with N2, but the zeolite bed showed an adsorption capacity threefold higher for CO2 than for N2 in the continuous operation with a Cl2 flow rate of 155 mmol/s and a total flow rate of 430± 3 mmol/s.

Xu, Mingxiu; Sang, Fengting; Jin, Yuqi; Fang, Benjie; Chen, Fang; Geng, Zicai; Li, Yongzhao

2008-11-01

216

Influence of Matrices on Oxygen Sensing of Three Sensing Films with Chemically Conjugated Platinum Porphyrin Probes and Preliminary Application for Monitoring of Oxygen Consumption of Escherichia coli (E. coli)  

PubMed Central

Oxygen sensing films were synthesized by a chemical conjugation of functional platinum porphyrin probes in silica gel, polystyrene (PS), and poly(2-hydroxyethyl methacrylate) (PHEMA) matrices. Responses of the sensing films to gaseous oxygen and dissolved oxygen were studied and the influence of the matrices on the sensing behaviors was investigated. Silica gel films had the highest fluorescence intensity ratio from deoxygenated to oxygenated environments and the fastest response time to oxygen. PHEMA films had no response to gaseous oxygen, but had greater sensitivity and a faster response time for dissolved oxygen than those of PS films. The influence of matrices on oxygen response, sensitivity and response time was discussed. The influence is most likely attributed to the oxygen diffusion abilities of the matrices. Since the probes were chemically immobilized in the matrices, no leaching of the probes was observed from the sensing films when applied in aqueous environment. One sensing film made from the PHEMA matrix was used to preliminarily monitor the oxygen consumption of Escherichia coli (E. coli) bacteria. E. coli cell density and antibiotics ampicillin concentration dependent oxygen consumption was observed, indicating the potential application of the oxygen sensing film for biological application.

Tian, Yanqing; Shumway, Bradley R.; Gao, Weimin; Youngbull, Cody; Holl, Mark R.; Johnson, Roger H.; Meldrum, Deirdre R.

2010-01-01

217

CARBON COATED (CARBONOUS) CATALYST IN EBULLATED BED REACTOR FOR PRODUCTION OF OXYGENATED CHEMICALS FROM SYNGAS/CO2  

SciTech Connect

There are a number of exothermic chemical reactions which might benefit from the temperature control and freedom from catalyst fouling provided by the ebullated bed reactor technology. A particularly promising area is production of oxygenated chemicals, such as alcohols and ethers, from synthesis gas, which can be economically produced from coal or biomass. The ebullated bed operation requires that the small-diameter ({approx}1/32 inch) catalyst particles have enough mechanical strength to avoid loss by attrition. However, all of the State Of The Art (SOTA) catalysts and advanced catalysts for the purpose are low in mechanical strength. The patented carbon-coated catalyst technology developed in our laboratory converts catalyst particles with low mechanical strength to strong catalysts suitable for ebullated bed application. This R&D program is concerned with the modification on the mechanical strength of the SOTA and advanced catalysts so that the ebullated bed technology can be utilized to produce valuable oxygenated chemicals from syngas/CO{sub 2} efficiently and economically. The objective of this R&D program is to study the technical and economic feasibility of selective production of high-value oxygenated chemicals from synthesis gas and CO{sub 2} mixed feed in an ebullated bed reactor using carbon-coated catalyst particles.

Peizheng Zhou

2001-10-26

218

CARBON COATED (CARBONOUS) CATALYST IN EBULLATED BED REACTOR FOR PRODUCTION OF OXYGENATED CHEMICALS FROM SYNGAS/CO2  

SciTech Connect

There are a number of exothermic chemical reactions which might benefit from the temperature control and freedom from catalyst fouling provided by the ebullated bed reactor technology. A particularly promising area is production of oxygenated chemicals, such as alcohols and ethers, from synthesis gas, which can be economically produced from coal or biomass. The ebullated bed operation requires that the small-diameter ({approx} 1/32 inch) catalyst particles have enough mechanical strength to avoid loss by attrition. However, all of the State Of The Art (SOTA) catalysts and advanced catalysts for the purpose are low in mechanical strength. The patented carbon-coated catalyst technology developed in our laboratory converts catalyst particles with low mechanical strength to strong catalysts suitable for ebullated bed application. This R&D program is concerned with the modification on the mechanical strength of the SOTA and advanced catalysts so that the ebullated bed technology can be utilized to produce valuable oxygenated chemicals from syngas/CO{sub 2} efficiently and economically. The objective of this R&D program is to study the technical and economic feasibility of selective production of high-value oxygenated chemicals from synthesis gas and CO{sub 2} mixed feed in an ebullated bed reactor using carbon-coated catalyst particles.

Peizheng Zhou

2000-11-17

219

Thermal, Mechanical and Chemical Analysis for VELOX -Verification Experiments for Lunar Oxygen Production  

NASA Astrophysics Data System (ADS)

One major aspect for the development of a long-term human presence on the moon will be sustainability and autonomy of any kind of a permanent base. Important resources, such as breathable air and water for the survival of the crew on the lunar surface will have to be extracted in-situ from the lunar regolith, the major resource on the Moon, which covers the first meter of the lunar surface and contains about 45 At the DLR Bremen we are interested in a compact and flexible lab experimenting facility, which shall demonstrate the feasibility of this process by extracting oxygen out of lunar Regolith, respectively soil simulants and certain minerals in the laboratory case. For this purpose, we have investigated important boundary conditions such as temperatures during the process, chemical reaction characteristics and material properties for the buildup of the facility and established basic requirements which shall be analyzed within this paper. These requirements have been used for the concept development and outline of the facility, which is currently under construction and will be subject to initial tests in the near future. This paper will focus mainly on the theoretical aspects of the facility development. Great effort has been put into the thermal and mechanical outline and pre-analysis of components and the system in a whole. Basic aspects that have been investigated are: 1. Selection of suitable materials for the furnace chamber configuration to provide a high-temperature capable operating mode. 2. Theoretical heat transfer analysis of the designed furnace chamber assembly with subsequent validation with the aid of measured values of the constructed demonstration plant. 3. Description of chemical conversion processes for Hydrogen reduction of Lunar Regolith with corresponding analysis of thermal and reaction times under different boundary conditions. 4. Investigation of the high-temperature mechanical behavior of the constructed furnace chamber with regard to thermal stability and especially to the hermetically sealed reactor due to internal Hydrogen atmosphere. In the end, we will give a first glimpse into the development of the test setup and first test results on the way to a superior test set-up and infrastructure with pre-and post-processing units such as feeding and extraction units and analysis of reaction products.

Lange, Caroline; Ksenik, Eugen; Braukhane, Andy; Richter, Lutz

220

Nitrogen-to-oxygen as a tracer of the chemical evolution of the Local and young Universe  

NASA Astrophysics Data System (ADS)

Oxygen optical emission-lines are used exhaustively as tracers of the metal content in gaseous nebulae ionized during different episodes of massive star formation. The high luminosity of these lines make them to be detected from the Local Universe up to starbursts at high redshift. Occasionally, in those cases where these lines cannot be measured due to the spectral coverage or to the redshift, nitrogen emission-lines are used instead. However, both nitrogen and oxygen have different nucleosynthetic origins, so the study of chemical abundances from nitrogen emission-lines introduces variables depending on the star formation history of each galaxy that must be taken into account. This contribution summarizes those risks involved in using metallicity tracers based on optical nitrogen emission lines and also describes the advantages of using instead the nitrogen-to-oxygen ratio as a tracer itself, based mainly on its independence on star formation rate, avoiding selection effects at high redshift.

Pérez-Montero, E.

2013-05-01

221

Absorption-based highly sensitive and reproducible biochemical oxygen demand measurement method for seawater using salt-tolerant yeast Saccharomyces cerevisiae ARIF KD-003.  

PubMed

Salt-tolerant yeast Saccharomyces cerevisiae ARIF KD-003 was applied to highly sensitive and reproducible absorbance-based biochemical oxygen demand (BOD(AB-ScII)) measurement for seawater. In the previous work, we have studied the BOD(AB-ScI) method using normal Baker's yeast S. cerevisiae, and the excellent feature of the Baker's yeast as uniformly sustainable in solution could successfully be utilized. However, the BOD(AB-ScI) responses were disappeared by the existence of chloride ion as well as seawater. In the present method, uniformity in solution was also observed with S. cerevisiae ARIF KD-003, and salt-tolerance of the yeast was observed even in saturate concentration of sodium chloride. Next, characterizations of the influences of pH and incubation temperature were investigated. After optimum conditions were obtained, two calibration curves were made between 0.33 and 22 mg O2 L(-1) BOD using standard solution of glucose glutamic acid (GGA) or mixture of GGA and artificial seawater. Then, excellent reproducibility as the averages of relative standard deviation (R.S.D.(av)) in two calibration curves (nine points each) was successfully obtained at 1.10% at pure water or 1.03% at artificial seawater standard, respectively. In addition, the 3 sigma lower detection limit was calculated to be 0.07 mg O2 L(-1) BOD, and 0.11 mg O2 L(-1) BOD was experimentally detected by increase of the sample volume at 1.5-folds. The storage stability of the S. cerevisiae ARIF KD-003 was obtained at least 4 weeks. PMID:18558133

Nakamura, Hideaki; Mogi, Yotaro; Hattori, Hisashi; Kita, Yutaka; Hattori, Daisuke; Yoshimura, Aki; Karube, Isao

2008-05-13

222

Defining Nutrient and Biochemical Oxygen Demand Baselines for Tropical Rivers and Streams in São Paulo State (Brazil): A Comparison Between Reference and Impacted Sites  

NASA Astrophysics Data System (ADS)

Determining reference concentrations in rivers and streams is an important tool for environmental management. Reference conditions for eutrophication-related water variables are unavailable for Brazilian freshwaters. We aimed to establish reference baselines for São Paulo State tropical rivers and streams for total phosphorus (TP) and nitrogen (TN), nitrogen-ammonia (NH4 +) and Biochemical Oxygen Demand (BOD) through the best professional judgment and the trisection methods. Data from 319 sites monitored by the São Paulo State Environmental Company (2005 to 2009) and from the 22 Water Resources Management Units in São Paulo State were assessed ( N = 27,131). We verified that data from different management units dominated by similar land cover could be analyzed together (Analysis of Variance, P = 0.504). Cumulative frequency diagrams showed that industrialized management units were characterized by the worst water quality (e.g. average TP of 0.51 mg/L), followed by agricultural watersheds. TN and NH4 + were associated with urban percentages and population density (Spearman Rank Correlation Test, P < 0.05). Best professional judgment and trisection (median of lower third of all sites) methods for determining reference concentrations showed agreement: 0.03 & 0.04 mg/L (TP), 0.31 & 0.34 mg/L (TN), 0.06 & 0.10 mg-N/L (NH4 +) and 2 & 2 mg/L (BOD), respectively. Our reference concentrations were similar to TP and TN reference values proposed for temperate water bodies. These baselines can help with water management in São Paulo State, as well as providing some of the first such information for tropical ecosystems.

Cunha, Davi G. F.; Dodds, Walter K.; Carmo Calijuri, Maria Do

2011-11-01

223

Ejector Chemical Oxygen-Iodine Laser with Supersonic Nozzle Bank Based on a Trip-Jet Mixing System  

Microsoft Academic Search

Nozzle banks for an ejector chemical oxygen-iodine laser consisting of two-dimensional slit nozzles with a trip-jet mixing system were tested in the cold- and hot-flow operation regimes. Horizontal Pitot scan experiments demonstrated that the mixing ability of the trips is excellent. The Mach number of the mixed flow was approximately 3. Gain measurements were conducted, and the results of these

Kazuyoku Tei; Kazuhiko Horioka; Mitsuo Nakajima; Daichi Sugimoto; Goro Watanabe; Shigeki Muto; Tomoo Fujioka

2008-01-01

224

Numerical simulation of laminar co-flow methane-oxygen diffusion flames: effect of chemical kinetic mechanisms  

Microsoft Academic Search

Laminar co-flow methane–oxygen flames issuing into the unconfined atmosphere have been studied. A numerical model, which employs different chemical kinetics sub-models, including a skeletal mechanism with 43 reaction steps and 18 species and four global reaction mechanisms (two 2-steps and two 4-steps mechanisms), and an optically thin radiation sub-model, has been employed in the simulations. Numerical model has been validated

Karnam Bhadraiah; Vasudevan Raghavan

2011-01-01

225

Effect of temperature on reduction reactivity of oxygen carrier particles in a fixed bed chemical-looping combustor  

Microsoft Academic Search

In a chemical-looping combustor (CLC), gaseous fuel is oxidized by metal oxide particle, e.g. oxygen carrier, in a reduction\\u000a reactor (combustor), and the greenhouse gas CO2 is separated from the exhaust gases during the combustion. In this study, NiO\\/bentonite particle was examined on the basis\\u000a of reduction reactivity, carbon deposition during reduction, and NOx formation during oxidation. Reactivity data for

Ho-Jung Ryu; Dal-Hee Bae; Gyoung-Tae Jin

2003-01-01

226

Theoretical and experimental studies of thick-section cutting with a chemical oxygen-iodine laser (COIL)  

Microsoft Academic Search

A simple mathematical model of thick-section stainless steel cutting with a high power chemical oxygen-iodine laser (COIL) is presented and compared with experimental results obtained with a 10-kilowatt COIL at the US Air Force`s Phillips Laboratory. This model uses a lumped-parameter technique to relate the cutting kerf depth with various process parameters and can be used to predict scaled laser

A. Kar; J. E. Scott; W. P. Latham

1996-01-01

227

An Inexpensive Electrode and Cell for Measurement of Oxygen Uptake in Chemical and Biochemical Systems.  

ERIC Educational Resources Information Center

The continuous measurement of oxygen consumption in an enzymatic reaction is a frequent experimental fact and extremely important in the enzymatic activity of oxygenase. An electrochemical system, based on a polarographic method, has been developed to monitor the oxygen uptake. The system developed and electrode used are described. (JN)

Brunet, Juan E.; And Others

1983-01-01

228

Chemical constraints on the water and total oxygen abundances in the deep atmosphere of Jupiter  

NASA Astrophysics Data System (ADS)

Recent observations of the global H2O mixing ratio in the Jovian troposphere have been interpreted as indicating a possible global depletion of water and of total oxygen in Jupiter's interior. The authors discuss the resulting implications for the abundances of important nonequilibrium trace gases that are mixed upward from Jupiter's interior. The calculations show that the observations of CO and the upper limit on SiH4 are incompatible with significant global water and total oxygen depletions in Jupiter's interior. Hence the observed low water vapor abundances must result from unexpected local condensation effects in the cloud-forming region rather than from planetary depletions in water and total oxygen.

Fegley, B.; Prinn, R. G.

1988-01-01

229

Computational fluid dynamics modeling of chemical looping combustion process with calcium sulphate oxygen carrier - article no. A19  

SciTech Connect

To concentrate CO{sub 2} in combustion processes by efficient and energy-saving ways is a first and very important step for its sequestration. Chemical looping combustion (CLC) could easily achieve this goal. A chemical-looping combustion system consists of a fuel reactor and an air reactor. Two reactors in the form of interconnected fluidized beds are used in the process: (1) a fuel reactor where the oxygen carrier is reduced by reaction with the fuel, and (2) an air reactor where the reduced oxygen carrier from the fuel reactor is oxidized with air. The outlet gas from the fuel reactor consists of CO{sub 2} and H{sub 2}O, while the outlet gas stream from the air reactor contains only N{sub 2} and some unused O{sub 2}. The water in combustion products can be easily removed by condensation and pure carbon dioxide is obtained without any loss of energy for separation. Until now, there is little literature about mathematical modeling of chemical-looping combustion using the computational fluid dynamics (CFD) approach. In this work, the reaction kinetic model of the fuel reactor (CaSO{sub 4}+ H{sub 2}) is developed by means of the commercial code FLUENT and the effects of partial pressure of H{sub 2} (concentration of H{sub 2}) on chemical looping combustion performance are also studied. The results show that the concentration of H{sub 2} could enhance the CLC performance.

Baosheng Jin; Rui Xiao; Zhongyi Deng; Qilei Song [Southeast University (China). Key Laboratory of Clean Coal Power Generation and Combustion Technology of Ministry of Education

2009-07-01

230

Control of chemical reaction involving dissolved oxygen using magnetic field gradient  

NASA Astrophysics Data System (ADS)

This study investigated the control of dissolved oxygen concentration using magnetic forces from gradient magnetic fields near a Nd Fe B permanent magnet. Maximum values of magnetic flux density and the product of the magnetic flux density and its gradient were 0.63 T and 44 T2/m, respectively. The magnet was placed under a Petri dish filled with 15 ml of 10% ammonia water. The Petri dish had a copper sheet in the center. Absorbance of tetraamminecopper(II) complex produced by the reaction in oxygen was measured using a spectrophotometer to observe oxygen concentration. Results showed that the magnetic field quantitatively enhanced tetraamminecopper(II) complex production. Moreover, remarkable enhancement of the copper complex production occurred in the magnetic field at less than 2 mm depth. The calculated magnetic force increase near the magnet surface supports this result. These results show that greater enhancement of the reaction rate occurs when the stronger magnetic force acts on oxygen molecules.

Aoyagi, Satoka; Yano, Akira; Yanagida, Yasutaka; Tanihira, Eiji; Tagawa, Akio; Iimoto, Mitsuo

2006-12-01

231

DEVICE FOR CONTROL OF OXYGEN PARTIAL PRESSURE  

DOEpatents

A device is described that can sense changes in oxygen partial pressure and cause a corresponding mechanical displacement sufficient to actuate meters, valves and similar devices. A piston and cylinder arrangement contains a charge of crystalline metal chelate pellets which have the peculiar property of responding to variations in the oxygen content of the ambient atmosphere by undergoing a change in dimension. A lever system amplifies the relative displacement of the piston in the cylinder, and actuates the controlled valving device. This partial pressure oxygen sensing device is useful in controlled chemical reactions or in respiratory devices such as the oxygen demand meters for high altitude aircraft.

Bradner, H.; Gordon, H.S.

1957-12-24

232

Homegrown Demand  

NSDL National Science Digital Library

The professor sells an announced number of M&M packets (or other inexpensive good) through an auction to derive a classroom demand schedule. The resulting demand schedule is displayed as a "curve" and facilitates discussion of consumer demand.

Swarthout, Todd

233

Structural Features Associated with Degradable and Persistent Chemicals.  

National Technical Information Service (NTIS)

A multivariate statistical method and a heuristic method were employed to examine the structural features associated with the persistence of degradation of 287 chemicals tested with the standard biochemical oxygen demand(BOD) procedure. The data base cons...

G. J. Niemi G. D. Veith R. R. Regal D. D. Vaishnav

1987-01-01

234

Oxygen Mass Transfer Coefficient (k sub L a') Consideration for Scale- Up Fermentation Systems at the Biotechnology Laboratory U.S. Army Edgewood Chemical Biological Center.  

National Technical Information Service (NTIS)

Volumetric oxygen mass transfer coefficients (kLa') were determined at different agitation speeds, airflow rates, and overhead pressures for a Micros 30, IF 150 and IF 1500 fermentation systems at U.S. Army Edgewood Chemical Biological Center's Biotechnol...

F. J. Kragl G. D. Ouellette M. H. Kim R. G. Thompson

2011-01-01

235

160 h of chemical-looping combustion in a 10 kW reactor system with a NiO-based oxygen carrier  

Microsoft Academic Search

Chemical-looping combustion, CLC, is a technology with inherent separation of the greenhouse gas CO2. The technique uses an oxygen carrier made up of particulate metal oxide to transfer oxygen from combustion air to fuel. In this work, an oxygen carrier consisting of 60% NiO and 40% NiAl2O4 was used in a 10kW CLC reactor system for 160h of operation with

Carl Linderholm; Alberto Abad; Tobias Mattisson; Anders Lyngfelt

2008-01-01

236

Silicon-on-glass pore network micromodels with oxygen-sensing fluorophore films for chemical imaging and defined spatial structure  

SciTech Connect

Pore network microfluidic models were fabricated by a silicon-on-glass technique that provides the precision advantage of dry etched silicon while creating a structure that is transparent across all microfluidic channels and pores, and can be imaged from either side. A silicon layer is bonded to an underlying borosilicate glass substrate and thinned to the desired height of the microfluidic channels and pores. The silicon is then patterned and through-etched by deep reactive ion etching (DRIE), with the underlying glass serving as an etch stop. After bonding on a transparent glass cover plate, one obtains a micromodel in oxygen impermeable materials with water wet surfaces where the microfluidic channels are transparent and structural elements such as the pillars creating the pore network are opaque. The micromodel can be imaged from either side. The advantageous features of this approach in a chemical imaging application are demonstrated by incorporating a Pt porphyrin fluorophore in a PDMS film serving as the oxygen sensing layer and a bonding surface, or in a polystyrene film coated with a PDMS layer for bonding. The sensing of a dissolved oxygen gradient was demonstrated using fluorescence lifetime imaging, and it is shown that different matrix polymers lead to optimal use in different ranges dissolved oxygen concentration. Imaging with the opaque pillars in between the observation direction and the continuous fluorophore film yields images that retain spatial information in the sensor image.

Grate, Jay W.; Kelly, Ryan T.; Suter, Jonathan D.; Anheier, Norman C.

2012-11-21

237

Chemical Budgets for Channel Catfish Ponds  

Microsoft Academic Search

Budgets for water, nitrogen, phosphorus, chemical oxygen demand (organic matter), and dissolved oxygen (DO) were estimated over a growing season (March-October) for three Alabama ponds used for culture of channel catfish Ictalurus punctatus. In addition to rainfall and runoff, 190 cm of water were applied from a pipe line to offset seepage and evaporation. Production of each kilogram of live

Claude E. Boyd

1985-01-01

238

Chemical tuning of electrochemical properties of Pt-skin surfaces for highly active oxygen reduction reactions.  

PubMed

Pt-skin surfaces were successfully fabricated by the chemical deposition of additional Pt on corrugated Pt-Ni nanoparticles with Pt-skeleton surfaces. Compared to the Pt-skin formed by heat annealing, the chemically-tuned Pt-skin had a higher Pt coordination number and surface crystallinity, which resulted in superior ORR activity and durability. PMID:23970167

Jung, Namgee; Chung, Young-Hoon; Chung, Dong Young; Choi, Kwang-Hyun; Park, Hee-Young; Ryu, Jaeyune; Lee, Sang-Young; Kim, Mansu; Sung, Yung-Eun; Yoo, Sung Jong

2013-09-25

239

Analysis of lasing in chemical oxygen-iodine lasers with unstable resonators using a geometric-optics model.  

PubMed

A simple geometric-optics model is developed that describes the power extraction in chemical oxygen-iodine lasers (COILs) with unstable resonators. The positive and negative branch unstable resonators with cylindrical mirrors that were recently used in COILs are studied theoretically. The optical extraction efficiency, spatial distributions of the intracavity radiation intensity in the flow direction, and the intensity in the far field are calculated for both kinds of resonator as a function of both the resonator and the COIL parameters. The optimal resonator magnifications that correspond to the maximum intensity in the far field are found. PMID:19412214

Barmashenko, Boris D

2009-05-01

240

Chemical Constraints on the Water and Total Oxygen Abundances in the Deep Atmosphere of Saturn  

NASA Astrophysics Data System (ADS)

Thermochemical equilibrium and kinetic calculations for the trace gases CO, PH3, and SiH4 give three independent constraints on the water and total oxygen abundances of Saturn's deep atmosphere. A lower limit to the water abundance of H2O/H2>=(1.7+0.7-0.4)×10-3 is given by CO chemistry, whereas an upper limit of H2O/H2<=(5.5+0.8-2.5)×10-3 is given by PH3 chemistry. A combination of the CO and PH3 constraints indicates a water enrichment on Saturn of 1.9-6.1 times the solar system abundance (H2O/H2=8.96×10-4). The total oxygen abundance must be at least 1.7 times the solar system abundance (O/H2=1.16×10-3) in order for SiH4 to remain below the detection limit of SiH4/H2<2×10-10. A combination of the CO, PH3, and SiH4 constraints suggests that the total oxygen abundance on Saturn is 3.2-6.4 times the solar system abundance. Our results indicate that oxygen on Saturn is less enriched than other heavy elements (such as C and P) relative to the solar system composition.

Visscher, Channon; Fegley, Bruce, Jr.

2005-04-01

241

The Effect of Chemically Inert Gases on Oxygen Consumption in Living Tissues.  

National Technical Information Service (NTIS)

The effect of N2, He, and A at normal pressures (approx. 560 mm. Hg) on the oxygen consumption of yeast cells, rat liver slices, and rat liver homogenates was studied. By utilizing both polarographic and Warburg technics, comparisons were made between 20%...

D. A. Maio J. R. Neville

1966-01-01

242

Chemical potentials of oxygen for fayalite-quartz-lron and fayalite-quartz-magnetite equilibria  

Microsoft Academic Search

The oxygen potentials corresponding to fayalite-quartz-iron (FQI) and fayalite-quartz-magnetite (FQM) equilibria have been\\u000a determined using solid-state galvanic cells: Pt,Fe + Fe2SiO4 + SiO2\\/(Y2O3)ZrO2\\/Fe + \\\\r\\

K. T. Jacob; G. M. Kale; G. N. K. Iyengar

1989-01-01

243

A ratiometric luminescent oxygen sensor based on a chemically functionalized quantum dot.  

PubMed

Nanoconjugates composed of CdSe-ZnS core-shell nanocrystals and pyrenyl ligands are shown to exhibit a double photoluminescence. Owing to the different response of the two emission signals towards oxygen, the nanocrystals function as high dynamic range ratiometric luminescent O(2) nanosensors. PMID:20730204

Amelia, Matteo; Lavie-Cambot, Aurélie; McClenaghan, Nathan D; Credi, Alberto

2010-08-23

244

Chemical Constraints on the Water and Total Oxygen Abundances in the Deep Atmosphere of Saturn  

NASA Astrophysics Data System (ADS)

Thermochemical equilibrium and kinetic calculations for the trace gases CO, PH3, and SiH4 give three independent constraints on the water and total oxygen abundances of Saturn's deep atmosphere. A lower limit to the water abundance of H2O/H2 > 1.7 x 10-3 is given by CO chemistry while an upper limit of H2O/H2 < 5.5 x 10-3 is given by PH3 chemistry. A combination of the CO and PH3 constraints indicates a water enrichment on Saturn of 1.9 to 6.1 times the solar system abundance (H2O/H2 = 8.96 x 10-4). The total oxygen abundance must be at least 1.7 times the solar system abundance (O/H2 = 1.16 x 10-3) in order for SiH4 to remain below a detection limit of SiH4/H2 < 2 x 10-10. A combination of the CO, PH3, and SiH4 constraints suggests that the total oxygen abundance on Saturn is 3.2 to 6.4 times the solar system abundance. Our results indicate that oxygen on Saturn is less enriched than other heavy elements (such as C and P) relative to a solar system composition. This work was supported by NASA NAG5-11958.

Visscher, C.; Fegley, B., Jr.

2004-12-01

245

CARBON COATED (CARBONOUS) CATALYST IN EBULLATED BED REACTOR FOR PRODUCTION OF OXYGENATED CHEMICALS FROM SYNGAS/CO2  

SciTech Connect

This report summarizes the work completed under DOE's Support of Advanced Fuel Research program, Contract No. DE-FG26-99FT40681. The contract period was October 2000 through September 2002. This R&D program investigated the modification of the mechanical strength of catalyst extrudates using Hydrocarbon Technologies, Inc. (HTI) carbon-coated catalyst technology so that the ebullated bed technology can be utilized to produce valuable oxygenated chemicals from syngas/CO{sub 2} efficiently and economically. Exothermic chemical reactions benefit from the temperature control and freedom from catalyst fouling provided by the ebullated bed reactor technology. The carbon-coated extrudates prepared using these procedures had sufficient attrition resistance and surface area for use in ebullated bed operation. The low cost of carbon coating makes the carbon-coated catalysts highly competitive in the market of catalyst extrudates.

Peizheng Zhou

2002-12-30

246

The Effects of Oxygen Plasma on the Chemical Composition and Morphology of the Ru Capping Layer of the Extreme Ultraviolet (EUV) Mask Blanks  

SciTech Connect

Contamination removal from extreme ultraviolet (EUV) mask surfaces is one of the most important aspects to improve reliability for the next generation of EUV lithography. We report chemical and morphological changes of the ruthenium (Ru) mask surface after oxygen plasma treatment using surface sensitive analytical methods: X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and transmission electron microscopy (TEM). Chemical analysis of the EUV masks shows an increase in the subsurface oxygen concentration, Ru oxidation and surface roughness. XPS spectra at various photoelectron takeoff angles suggest that the EUV mask surface was covered with chemisorbed oxygen after oxygen plasma treatment. It is proposed that the Kirkendall effect is the most plausible mechanism that explains the Ru surface oxidation. The etching rate of the Ru capping layer by oxygen plasma was estimated to be 1.5 {+-} 0.2 {angstrom}/min, based on TEM cross sectional analysis.

Belau, Leonid; Park, Jeong Y.; Liang, Ted; Somorjai, Gabor A.

2008-06-07

247

A Preliminary Evaluation of the Effect of Dissolved Oxygen on Nitrification and Other Biological Process Parameters  

Microsoft Academic Search

This work examines the relationship between dissolved oxygen level and the nitrification process in municipal wastewaters. Carbon removal, chemical oxygen demand removal and sludge viability were also investigated. Parallel bench scale continuous activated sludge reactors operating at dissolved oxygen levels of approximately 2 mg\\/l and 8 mg\\/l were used.\\u000aThe high dissolved oxygen level sludge produced significantly more nitrate nitrogen

Stuart N. Lawrence

1978-01-01

248

Chemical Mechanical Polishing for Oxygen Free Copper with Manganese Oxide Abrasives  

Microsoft Academic Search

The purpose of this study is to make clear the polishing characteristics of the manganese oxide slurry for wire material of Cu. To examine the polishing characteristics of the manganese oxide slurry, a series of polishing experiments for oxygen free copper have been carried out by using MnO2, Mn2O3 and Al2O3 as abrasive grains and polishing properties have been discussed.

Ryunosuke Sato; Yoshio Ichida; Yoshitaka Morimoto; Kenji Shimizu

2008-01-01

249

In vitro effects of oxygen on physico-chemical properties of horse erythrocyte membrane  

Microsoft Academic Search

Whether direct exposure to different concentrations (0%, 13%, 100%) of oxygen may affect horse erythrocyte membrane fluidity (EMF) and fatty acid (FA) composition was studied during 1 (T60) and 2h (T120) exposure. EMF was investigated at the head group level and hydrophobic core thanks to phosphorus nucleus 31 (31P) nuclear magnetic resonance (31P NMR) and electronic paramagnetic resonance (EPR) using

Karine Portier; Michel Guichardant; Jean-Claude Debouzy; David Crouzier; Ingrid Geraud; Nathalie Kirschvink; Pierre Lekeux; Nicole Fellmann; Jean Coudert

2007-01-01

250

The effects of oxygen on controlling the number of carbon layers in the chemical vapor deposition of graphene on a nickel substrate.  

PubMed

While oxygen is typically considered undesirable during the chemical vapor deposition (CVD) of graphene on metal substrates, we demonstrate that suitable amounts of oxygen in the CVD system can in fact improve the uniformity and thickness control of the graphene film. The role of oxygen on the CVD of graphene on a nickel substrate using a propylene precursor was investigated with various surface analytical techniques. It was found that the number of carbon layers in the deposited graphene sample decreases as the concentration of oxygen increases. In particular, single-layer graphene can be easily obtained with an oxygen/propylene ratio of 1/9. In the presence of oxygen, a thin layer of nickel oxide will form on the substrate. The oxide layer decreases the concentration of carbon atoms dissolved in the nickel substrate and results in graphene samples with a decreasing number of carbon layers. PMID:23575390

Dou, Wei-Dong; Yang, Qingdan; Lee, Chun-Sing

2013-04-11

251

The effects of oxygen on controlling the number of carbon layers in the chemical vapor deposition of graphene on a nickel substrate  

NASA Astrophysics Data System (ADS)

While oxygen is typically considered undesirable during the chemical vapor deposition (CVD) of graphene on metal substrates, we demonstrate that suitable amounts of oxygen in the CVD system can in fact improve the uniformity and thickness control of the graphene film. The role of oxygen on the CVD of graphene on a nickel substrate using a propylene precursor was investigated with various surface analytical techniques. It was found that the number of carbon layers in the deposited graphene sample decreases as the concentration of oxygen increases. In particular, single-layer graphene can be easily obtained with an oxygen/propylene ratio of 1/9. In the presence of oxygen, a thin layer of nickel oxide will form on the substrate. The oxide layer decreases the concentration of carbon atoms dissolved in the nickel substrate and results in graphene samples with a decreasing number of carbon layers.

Dou, Wei-Dong; Yang, Qingdan; Lee, Chun-Sing

2013-05-01

252

The chemical character and behaviour of phosphorus in poorly oxygenated sediments from open sea to organic-rich inner bay in the Baltic Sea  

Microsoft Academic Search

The chemical composition and vertical distribution of phosphorus (P) in poorly oxygenated sediments in a continuum extending\\u000a from the open Baltic Sea towards an organic-rich inner bay were characterized by sequential extraction to examine the potential\\u000a for release of sediment P. The chemical composition of P was related to chemical and physical characteristics of the sediments\\u000a and the chemistry of

K. Lukkari; M. Leivuori; A. Kotilainen

2009-01-01

253

Using continuous and pulse experiments to compare two promising nickel-based oxygen carriers for use in chemical-looping technologies  

Microsoft Academic Search

Chemical-looping technologies have obtained widespread recognition as power or hydrogen production units with inherent carbon capture in a future scenario where CO2 capture and storage (CCS) is reality. In this paper three different techniques are described; chemical-looping combustion and two categories of chemical-looping reforming. The three techniques are all based on oxygen carriers that are circulating between an air- and

Marcus Johansson; Tobias Mattisson; Anders Lyngfelt; Alberto Abad

2008-01-01

254

Chemisorption of hydrogen and oxygen atoms on a cobalt surface: A quantum chemical cluster model study  

SciTech Connect

The chemisorption of atomic hydrogen and oxygen on a cobalt surface has been studied on a five-atom cluster model using one-electron effective core potential (le{sup -} ECP) and all-electron calculations at the ab initio SCF and MCPF levels. Also, density functional calculations have been carried out. The different approaches are evaluated. The le{sup -} ECP has been compared to similar ECPS for nickel and copper. Our results indicate that this approach is valid also for cobalt. Different contributions to the cluster-adsorbate bonding energy are discussed. 31 refs., 1 fig., 1 tab.

Swang, O.; Faegri, K. Jr. [Univ. of Oslo (Norway); Gropen, O. [Univ. of Tromso (Norway)] [and others

1996-01-05

255

Review of the simple model for metal cutting with the chemical oxygen-iodine laser  

Microsoft Academic Search

The COIL has drawn considerable attention owing to its short, fiber-deliverable wavelength, scalability to very high powers, and nearly diffraction-limited optical quality. These unique abilities make it an ideal candidate for rapid cutting of thick metals and other laser materials processing applications. Cutting experiments have been conducted at the Air Force Research Laboratory Chemical Laser Facility for a number of

William P. Latham; Aravinda Kar

2000-01-01

256

Chemicals and energy co-generation from direct hydrocarbons\\/oxygen proton exchange membrane fuel cell  

Microsoft Academic Search

A proton exchange membrane fuel cell for chemicals and energy co-generation was set up with hydrocarbons ethane, propane and butane as fuels, and the electrochemical performance of the cell was studied by using linear potential sweep, alternating current impedance and gas chromatography. The cell performance can be improved to a great extent by increasing the platinum load in the catalyst,

W. S. Li; D. S. Lu; J. L. Luo; K. T. Chuang

2005-01-01

257

Protein adsorption resistance and oxygen permeability of chemically crosslinked phospholipid polymer hydrogel for ophthalmologic biomaterials.  

PubMed

The biomimetic structure of a polymer hydrogel bearing phosphorylcholine groups was obtained from 2-methacryloyloxyethylphosphorylcholline (MPC) and a novel crosslinker, 2-(methacryloyloxy)ethyl-N-(2-methacryloyloxy)ethyl]phosphorylcholine (MMPC), to prepare biocompatible ocular materials. MMPC is a dimethacrylate with phosphorylcholine-analogous linkage. Previous reports clarified that the affinity of MMPC to MPC enables the water contents and mechanical properties of the poly(MPC) hydrogels to be varied without disturbing the bulk phases. In this study, we examined the protein adsorption resistance, water wettability, oxygen permeability, and electrolyte permeability of the mechanically enhanced poly(MPC) hydrogel crosslinked with MMPC. The amount of protein adsorbed on this hydrogel was 0.9 microg/cm(2), which accounted for 30% of Omafilcon A and 3% of Etafilcon A. Water contact angle experiments revealed the high wettability of the poly(MPC) hydrogels. The oxygen permeability and NaCl diffusion constant of the poly(MPC) hydrogels were 64 barrer and 48 x 10(-6) cm(2)/s, respectively. This high permeability resulted from the high water content, similar to the case of the human cornea. These results suggested that poly(MPC) hydrogels have good potential for use in ophthalmologic biomaterials. PMID:18777582

Goda, Tatsuro; Matsuno, Ryosuke; Konno, Tomohiro; Takai, Madoka; Ishihara, Kazuhiko

2009-04-01

258

The functional significance of ventilation frequency, and its relationship to oxygen demand in the resting brown long-eared bat, Plecotus auritus.  

PubMed

Mean oxygen consumption and simultaneous ventilation frequency of nine non-reproductive brown long-eared bats (body mass 8.53-13.33 g) were measured on 159 occasions. Ambient (chamber) temperature at which the measurements were made ranged from 10.8 to 41.1 degrees C. Apneic ventilation occurred in 22 of the 59 measurements made when mean oxygen consumption was less than 0.5 ml.min-1. No records of apneic ventilation were obtained when it was over 0.5 ml.min-1. The relationship between ventilation frequency and mean oxygen consumption depended on whether ventilation was apneic or non-apneic. When ventilation was non-apneic the relationship was positive and log-linear. When ventilation was apneic the relationship was log-log. Within the thermoneutral zone ventilation frequency was not significantly different from that predicted from allometric equations for a terrestrial mammal of equivalent body mass, but was significantly greater than that predicted for a bird. A reduction in the amount of oxygen consumed per breath occurred at ambient temperatures above the upper critical temperature (39 degrees C). PMID:1592909

Webb, P I; Hays, G C; Speakman, J R; Racey, P A

1992-01-01

259

Chemical deposition of platinum nanoparticles on iridium oxide for oxygen electrode of unitized regenerative fuel cell  

Microsoft Academic Search

Platinum nanoparticles were deposited on the surface of IrO2 by chemical reduction. The morphology and structure of nanostructural Pt\\/IrO2 composites were characterized by XRD, EDX and FE-SEM. The reduction of PtCl62- ions in sodium borohydride aqueous solution containing sodium dodecylbenzenesulfonate (SDBS) additive leads to a fine dispersion and high loading of platinum nanoparticles on IrO2 without serious aggregation. A slight

Wenli Yao; Jun Yang; Jiulin Wang; Yanna Nuli

2007-01-01

260

Experiments on chemical looping combustion of coal with a NiO based oxygen carrier  

Microsoft Academic Search

A chemical looping combustion process for coal using interconnected fluidized beds with inherent separation of CO2 is proposed in this paper. The configuration comprises a high velocity fluidized bed as an air reactor, a cyclone, and a spout-fluid bed as a fuel reactor. The high velocity fluidized bed is directly connected to the spout-fluid bed through the cyclone. Gas composition

Laihong Shen; Jiahua Wu; Jun Xiao

2009-01-01

261

Study of oxygen-containing groups in a series of graphite oxides: Physical and chemical characterization  

Microsoft Academic Search

Some graphite oxides with different degrees of oxidation have been prepared by using a modified Staudenmaier method. The oxidation process has been studied by using different techniques: elementary analysis, gas adsorption, X-ray diffraction, FT-IR, XPS and 13C-NMR. The influence of the oxidation degree on the appearance and evolution of new chemical groups in the samples has been analyzed. The oxidation

C. Hontoria-Lucas; A. J. López-Peinado; J. de D. López-González; M. L. Rojas-Cervantes; R. M. Martín-Aranda

1995-01-01

262

Electrochemical and Structural Study of a Chemically Dealloyed PtCu Oxygen Reduction Catalyst  

PubMed Central

A carbon-supported, dealloyed platinum-copper (Pt-Cu) oxygen reduction catalyst was prepared using a multi-step synthetic procedure. Material produced at each step was characterized using high angle annular dark field scanning transmission electron microscopy (HAADF-STEM), electron energy loss spectroscopy (EELS) mapping, x-ray absorption spectroscopy (XAS), x-ray diffraction (XRD), and cyclic voltammetry (CV), and its oxygen reduction reaction (ORR) activity was measured by a thin-film rotating disk electrode (TF-RDE) technique. The initial synthetic step, a co-reduction of metal salts, produced a range of poorly crystalline Pt, Cu, and Pt-Cu alloy nanoparticles that nevertheless exhibited good ORR activity. Annealing this material alloyed the metals and increased particle size and crystallinity. TEM shows the annealed catalyst to include particles of various sizes, large (>25 nm), medium (12–25 nm), and small (<12 nm). Most of the small and medium-sized particles exhibited a partial or complete coreshell (Cu-rich core and Pt shell) structure with the smaller particles typically having more complete shells. The appearance of Pt shells after annealing indicates that they are formed by a thermal diffusion mechanism. Although the specific activity of the catalyst material was more than doubled by annealing, the concomitant decrease in Pt surface area resulted in a drop in its mass activity. Subsequent dealloying of the catalyst by acid treatment to partially remove the copper increased the Pt surface area by changing the morphology of the large and some medium particles to a “Swiss cheese” type structure having many voids. The smaller particles retained their core-shell structure. The specific activity of the catalyst material was little reduced by dealloying, but its mass activity was more than doubled due to the increase in surface area. The possible origins of these results are discussed in this report.

Dutta, Indrajit; Carpenter, Michael K; Balogh, Michael P; Ziegelbauer, Joseph M; Moylan, Thomas E; Atwan, Mohammed H; Irish, Nicholas P

2013-01-01

263

Electrochemical and Structural Study of a Chemically Dealloyed PtCu Oxygen Reduction Catalyst  

SciTech Connect

A carbon-supported, dealloyed platinum-copper (Pt-Cu) oxygen reduction catalyst was prepared using a multistep synthetic procedure. Material produced at each step was characterized using high-angle annular dark-field scanning transmission electron microscopy, electron energy loss spectroscopy mapping, X-ray absorption spectroscopy, X-ray diffraction, and cyclic voltammetry, and its oxygen reduction reaction (ORR) activity was measured by a thin-film rotating disk electrode technique. The initial synthetic step, a coreduction of metal salts, produced a range of poorly crystalline Pt, Cu, and Pt-Cu alloy nanoparticles that nevertheless exhibited good ORR activity. Annealing this material alloyed the metals and increased particle size and crystallinity. Transmission electron microscopy shows the annealed catalyst to include particles of various sizes, large (>25 nm), medium (12-25 nm), and small (<12 nm). Most of the small and medium-sized particles exhibited a partial or complete core-shell (Cu-rich core and Pt shell) structure with the smaller particles typically having more complete shells. The appearance of Pt shells after annealing indicates that they are formed by a thermal diffusion mechanism. Although the specific activity of the catalyst material was more than doubled by annealing, the concomitant decrease in Pt surface area resulted in a drop in its mass activity. Subsequent dealloying of the catalyst by acid treatment to partially remove the copper increased the Pt surface area by changing the morphology of the large and some medium particles to a 'Swiss cheese' type structure having many voids. The smaller particles retained their core-shell structure. The specific activity of the catalyst material was little reduced by dealloying, but its mass activity was more than doubled due to the increase in surface area. The possible origins of these results are discussed in this report.

Dutta, Indrajit; Carpenter, Michael K.; Balogh, Michael P.; Ziegelbauer, Joseph M.; Moylan, Thomas E.; Atwan, Mohammed H.; Irish, Nicholas P. (Trison Business Solutions); (General Motors Corp.)

2010-10-22

264

Mapping of the range of operational conditions for Cu, Fe, and Ni-based oxygen carriers in chemical-looping combustion  

Microsoft Academic Search

Chemical-looping combustion (CLC) is a two-step combustion process that produces a pure CO2 stream, ready for compression and sequestration. A CLC system is composed by two reactors, an air and a fuel reactor, and an oxygen carrier (OC) circulating between the reactors, which transfers the oxygen necessary for the fuel combustion from the air to the fuel. This system can

Alberto Abad; Juan Adánez; Francisco García-Labiano; Luis F. de Diego; Pilar Gayán; Javier Celaya

2007-01-01

265

A simplified analytic model for gain saturation and power extraction in the flowing chemical oxygen-iodine laser  

SciTech Connect

This paper describes the development of a simplified saturation model (SSM) for predicting power extraction from a chemical oxygen-iodine laser (COIL). Using the Fabry-Perot gain saturation assumption, analytic expressions for COIL extraction efficiency are presented for both constant-density and variable-density cavity conditions. The model treats mirror scattering, nonsaturable distributed losses, and diffractive losses from the mode-limiting aperture and is shown to be in excellent agreement with experimental COIL power extraction data. A comparison of the model with the Rigrod power extraction model is presented showing that the Rigrod model accurately predicts COIL extraction efficiency only in the limit that the COIL device no longer behaves as a transfer laser.

Hager, G.D.; Helms, C.A.; Truesdell, K.A. [Phillips Lab., Kirtland AFB, NM (United States); Plummer, D.; Erkkila, J.; Crowell, P. [Logicon RDA, Albuquerque, NM (United States)

1996-09-01

266

Decontamination of chemical-warfare agent simulants by polymer surfaces doped with the singlet oxygen generator zinc octaphenoxyphthalocyanine.  

PubMed

Using reactive singlet oxygen ((1)O2), the oxidation of chemical-warfare agent (CWA) simulants has been demonstrated. The zinc octaphenoxyphthalocyanine (ZnOPPc) complex was demonstrated to be an efficient photosensitizer for converting molecular oxygen (O2) to (1)O2 using broad-spectrum light (450-800 nm) from a 250 W halogen lamp. This photosensitization produces (1)O2 in solution as well as within polymer matrices. The oxidation of 1-naphthol to naphthoquinone was used to monitor the rate of (1)O2 generation in the commercially available polymer film Hydrothane that incorporates ZnOPPc. Using electrospinning, nanofibers of ZnOPPc in Hydrothane and polycarbonate were formed and analyzed for their ability to oxidize demeton-S, a CWA simulant, on the surface of the polymers and were found to have similar reactivity as their corresponding films. The Hydrothane films were then used to oxidize CWA simulants malathion, 2-chloroethyl phenyl sulfide (CEPS), and 2-chloroethyl ethyl sulfide (CEES). Through this oxidation process, the CWA simulants are converted into less toxic compounds, thus decontaminating the surface using only O2 from the air and light. PMID:24060426

Gephart, Raymond T; Coneski, Peter N; Wynne, James H

2013-10-04

267

Chemical, mechanical and microstructural characterization of low-oxygen containing silicon carbide fibers with ceramic coatings  

Microsoft Academic Search

Room temperature tensile strengths of as-received Hi-Nicalon fibers and those having BN\\/SiC, p-BN\\/SiC, and p-B(Si)N\\/SiC surface coatings, deposited by chemical vapor deposition, were measured using an average fiber diameter of 13.5µm. The Weibull statistical parameters were determined for each fiber. The average tensile strength of uncoated Hi-Nicalon was 3.19 ± 0.73 GPa with a Weibull modulus of 5.41. Strength of

N. P. Bansal; Y. L. Chen

1998-01-01

268

Electron spin resonance and luminescence spectroscopic observation and kinetic study of chemical and physical singlet oxygen quenching by resveratrol in methanol.  

PubMed

Electron spin resonance (ESR) spectroscopy and near-infrared (NIR) fluorescence spectroscopy were performed to observe singlet oxygen quenching by resveratrol. Resveratrol greatly decreased the 2,2,6,6-Tetramethyl-4-piperidone-N-oxyl radical signal as determined by ESR spectroscopy. Resveratrol also efficiently decreased luminescence emission at 1268 nm as studied with a NIR spectrofluorometer, showing positive evidence of singlet oxygen quenching by resveratrol. The total singlet oxygen quenching rate constant (kr+kq) of resveratrol in methanol was determined to be 2.55×10(7) M(-1) s(-1). The singlet oxygen chemical quenching rate constant (kr) of resveratrol was calculated by measuring its reaction rate with singlet oxygen relative to that of ?-terpinene in the same solution under light illumination. The kr value of resveratrol was 1.15×10(6) M(-1) s(-1). The percent partition of chemical quenching over total singlet oxygen quenching (kr×100)/(kr+kq) for resveratrol was 5.11%. The results showed that resveratrol quenches singlet oxygen almost exclusively through the mechanism of physical quenching. Resveratrol showed a protective activity similar to that of BHA on the methylene blue sensitized photooxidation of ?-terpinene. This unambiguously explains the mechanism of how resveratrol protects tissues and cells in biological systems or important nutrients in food systems against their photosensitized oxidations. PMID:21038912

Jung, Mun Yhung; Choi, Dong Seong

2010-11-01

269

Chemical role of oxygen plasma in wafer bonding using borosilicate glasses  

NASA Astrophysics Data System (ADS)

Plasma-treated oxide layers are commonly used in wafer bonding applications. Borosilicate glass (BSG) layers deposited by low-pressure chemical vapor deposition treated with an O2 plasma in reactive ion etching mode for 5 min at 0.6 W/cm2 and rinsed with DI H2O readily bond to GaAs and Si. The chemical role of this prebonding treatment was investigated using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. The peak intensities for both the Si-O and B-O absorbance bands decreased in intensity as a result of the plasma treatment is consistent with the uniform sputtering of 9.8 nm+/-0.8 nm of BSG. Polarization dependent ATR-FTIR revealed that the H2O/OH absorbance bands decreased in peak intensity with the OH groups being preferentially oriented perpendicular to the sample surface after the plasma treatment. The subsequent DI H2O rinse restores the water to the surface while removing B2O3 from the BSG layer. This prebonding treatment, therefore, results in a hydrophilic bond, but alters the composition of the BSG film at the bonded interface.

Hansen, D. M.; Albaugh, C. E.; Moran, P. D.; Kuech, T. F.

2001-11-01

270

STUDIES OF MECHANISMS OF CHEMICAL RADIATION PROTECTION IN VIVO. II. EFFECT OF HIGH PRESSURE OXYGEN ON RADIOPROTECTION IN VIVO AND ITS RELATIONSHIP TO 'OXYGEN POISONING'  

Microsoft Academic Search

Pure oxygen respired at 45 psi gage-pressure by rats during or ; immediately after whole-body x irradiation did not significantly alter LDââ ; (30 days) and LDââ (30 days) survival doses. Oxygen respired at 60 psi ; gage-pressure completely abolished the protective effect in vivo of histaraine ; and adrenalin and substantially reduced that of 5-hydroxytryptamine (5HT). The ; radioprotective

H. A. S. van den Brenk; Dana Jamieson

1962-01-01

271

Chemical compatibility of a TiAl-Nb melt with oxygen-free crucible ceramics made of aluminum nitride  

NASA Astrophysics Data System (ADS)

The problem of uncontrolled oxygen contamination of intermetallic TiAl ingots is considered for the application of crucibles and molds based on traditional oxide ceramics. A synthesized Ti-45.9Al-8Nb (at %) alloy is solidified in alternative oxygen-free crucibles made of high-purity aluminum nitride (99.99% AlN) upon holding at 1670°C for 5, 12, and 25 min and subsequent quenching in a high-purity argon atmosphere. The initial material and the solidified ingots are studied by scanning electron microscopy, optical microscopy, X-ray diffraction, electron-probe microanalysis, and gas-content chemical analysis. The key features of the interaction of the TiAl-Nb melt with AlN ceramics are revealed. Partial thermal dissociation of the crucible material according to the reaction AlN ? Al + N and the reaction of atomic nitrogen with the melt lead to the formation of a solid 6.4-?m-thick TiN coating on the ingot surface and provide perfect wettability of the crucible by the melt and easy removal of solidified casting items from the mold. The TiN coating serves as a diffusion barrier that hinders the diffusion of nitrogen and residual oxygen from the pores in the crucible toward the melt. As a result, no oxide particles are detected in the ingots. However, few single microprecipitates of two nitride phases ((Ti,Al) x N y , NbN) are detected in the near-bottom region, 300 ?m thick, in the alloy after holding at 1670°C for 25 min. The total oxygen contamination in a two-phase ?2 + ? ingot does not exceed 1100 wt ppm, which is 1.5-2 times lower than that obtained in the experiments performed with modern advanced oxide crucibles made of yttrium ceramics Y2O3. AlN is shown to be a promising crucible material that can be considered as an alternative to oxide ceramics in the metallurgy of TiAl intermetallics.

Kartavykh, A. V.; Cherdyntsev, V. V.

2008-12-01

272

Effect of temperature on reduction of CaSO{sub 4} oxygen carrier in chemical-looping combustion of simulated coal gas in a fluidized bed reactor  

SciTech Connect

Chemical-looping combustion (CLC) is a promising combustion technology for gaseous and solid fuel with efficient use of energy and inherent separation of CO{sub 2}. The concept of a coal-fueled CLC system using, calcium sulfate (CaSO{sub 4}) as oxygen carrier is proposed in this study. Reduction tests of CaSO{sub 4} oxygen carrier with simulated coal gas were performed in a laboratory-scale fluidized bed reactor in the temperature range of 890-950{degree}C. A high concentration of CO{sub 2} was obtained at the initial reduction period. CaSO{sub 4} oxygen carrier exhibited high reactivity initially and decreased gradually at the late period of reduction. The sulfur release during the reduction of CaSO{sub 4} as oxygen carrier was also observed and analyzed. H{sub 2} and CO{sub 2} conversions were greatly influenced by reduction temperature. The oxygen carrier conversion and mass-based reaction rates during the reduction at typical temperatures were compared. Higher temperatures would enhance reaction rates and result in high conversion of oxygen carrier. An XRD patterns study indicated that CaS was the dominant product of reduction and the variation of relative intensity with temperature is in agreement with the solid conversion. ESEM analysis indicated that the surface structure of oxygen carrier particles changed significantly from impervious to porous after reduction. EDS analysis also demonstrated the transfer of oxygen from the oxygen carrier to the fuel gas and a certain amount of sulfur loss and CaO formation on the surface at higher temperatures. The reduction kinetics of CaSO{sub 4} oxygen carrier was explored with the shrinking unreacted-core model. The apparent kinetic parameters were obtained, and the kinetic equation well predicted the experimental data. Finally, some basic considerations on the use of CaSO{sub 4} oxygen carrier in a CLC system for solid fuels were discussed.

Song, Q.L.; Xiao, R.; Deng, Z.Y.; Shen, L.H.; Xiao, J.; Zhang, M.Y. [Southeast University, Nanjing (China)

2008-12-15

273

Ventilatory accommodation of oxygen demand and respiratory water loss in kangaroos from mesic and arid environments, the eastern grey kangaroo (Macropus giganteus) and the red kangaroo (Macropus rufus).  

PubMed

We studied ventilation in kangaroos from mesic and arid environments, the eastern grey kangaroo (Macropus giganteus) and the red kangaroo (Macropus rufus), respectively, within the range of ambient temperatures (T(a)) from -5 degrees to 45 degrees C. At thermoneutral temperatures (Ta=25 degrees C), there were no differences between the species in respiratory frequency, tidal volume, total ventilation, or oxygen extraction. The ventilatory patterns of the kangaroos were markedly different from those predicted from the allometric equation derived for placentals. The kangaroos had low respiratory frequencies and higher tidal volumes, even when adjustment was made for their lower basal metabolism. At Ta>25 degrees C, ventilation was increased in the kangaroos to facilitate respiratory water loss, with percent oxygen extraction being markedly lowered. Ventilation was via the nares; the mouth was closed. Differences in ventilation between the two species occurred at higher temperatures, and at 45 degrees C were associated with differences in respiratory evaporative heat loss, with that of M. giganteus being higher. Panting in kangaroos occurred as a graded increase in respiratory frequency, during which tidal volume was lowered. When panting, the desert red kangaroo had larger tidal volumes and lower respiratory frequencies at equivalent T(a) than the eastern grey kangaroo, which generally inhabits mesic forests. The inference made from this pattern is that the red kangaroo has the potential to increase respiratory evaporative heat loss to a greater level. PMID:10893178

Dawson, T J; Munn, A J; Blaney, C E; Krockenberger, A; Maloney, S K

274

Chemical Hypoxia-Induced Cell Death in Human Glioma Cells: Role of Reactive Oxygen Species, ATP Depletion, Mitochondrial Damage and Ca 2+  

Microsoft Academic Search

This study was undertaken to evaluate whether chemical hypoxia-induced cell injury is a result of reactive oxygen species (ROS) generation, ATP depletion, mitochondrial permeability transition, and an increase in intracellular Ca2+, in A172 cells, a human glioma cell line. Chemical hypoxia was induced by incubating cells with antimycin A, an inhibitor of mitochondrial electron transport, in a glucose-free medium. Exposure

Jae Ick Jeong; Young Woo Lee; Yong Keun Kim

2003-01-01

275

Theory of chemical bonds in metalloenzymes - Manganese oxides clusters in the oxygen evolution center -  

NASA Astrophysics Data System (ADS)

In early 1980 we have initiated broken-symmetry (BS) MO theoretical calculations of transition-metal oxo species M = O (M = Ti,V,Cr,Mn,Fe,Ni,Cu) to elucidate the nature of d?-p? and d?-p? bonds. It has been concluded that high-valent M = O species such as [Mn(IV) = O]2+ and [Fe(IV) = O]2+ exhibit electrophilic property in a sharp contrast with nucleophilic character of low-valent M = O bonds: [M(II)O2-]0, and closed-shell d?-p? bonds of high-valent M = O species often suffer the triplet-instability, giving rise to open-shell (BS) configurations with significant metal-diradical (MDR) character: •M-O•: note that these bonds are therefore regarded as typical examples of strongly correlated electron systems. Because of the MDR character, 1,4-metal diradical mechanism was indeed preferable to four-centered mechanism in the case of addition reaction of naked Mn(IV) = O to ethylene. Recently the manganese-oxo species have been receiving renewed interest in relation to catalytic cycle of oxygen evolution from water molecules in the photosynthesis II (PSII) system. Accumulated experimental results indicate that this process is catalyzed with four manganese oxide clusters coordinated with calcium ion (CaMn4O4). Past decade we have performed BS MO theoretical investigations of manganese oxide clusters related to CaMn4O4. These calculations have elucidated that high-valent Mn(X) = O (X = IV,V) bonds exhibit intermediate MDR character (y=40-60%) in the case of total low-spin (LS) configuration but the MDR character decreases with coordination of Ca2+ and water molecules. While the MDR character of the Mn-oxo bonds becomes very high at the high-spin (HS) configuration. Our computational results enabled us to propose two possible mechanisms on the theoretical ground: (A) electrophilic (EP) mechanism and (B) radical coupling (RC) mechanism. The theoretical results indicate that the EP mechanism is preferable for the low-spin (LS) state in polar media like in the protein environments (native OEC), whereas the RC mechanism is feasible at the state without such environmental stabilization: local singlet and local triplet diradical mechanisms are proposed for the OO coupling process. Possibilities of EP and RC mechanisms are examined in comparison with a lot of experimental results accumulated and theoretical results with several groups.

Yamaguchi, K.; Shoji, M.; Saito, T.; Isobe, H.; Yamada, S.; Nishihara, S.; Kawakami, T.; Kitagawa, Y.; Yamanaka, S.; Okumura, M.

2012-12-01

276

Operation of a 10 kWth chemical-looping combustor during 200 h with a CuO–Al 2O 3 oxygen carrier  

Microsoft Academic Search

Chemical-looping combustion (CLC) is an attractive technology to decrease greenhouse gas emissions affecting global warming, because it is a combustion process with inherent CO2 separation and therefore without needing extra equipment for CO2 separation and low penalty in energy demand. The CLC concept is based on the split of a conventional combustion of gas fuel into separate reduction and oxidation

Luis F. de Diego; Francisco Garc?´a-Labiano; Pilar Gayán; Javier Celaya; José M. Palacios; Juan Adánez

2007-01-01

277

Review of the simple model for metal cutting with the chemical oxygen-iodine laser  

NASA Astrophysics Data System (ADS)

The COIL has drawn considerable attention owing to its short, fiber-deliverable wavelength, scalability to very high powers, and nearly diffraction-limited optical quality. These unique abilities make it an ideal candidate for rapid cutting of thick metals and other laser materials processing applications. Cutting experiments have been conducted at the Air Force Research Laboratory Chemical Laser Facility for a number of metals including stainless steel, nickel, copper, titanium and aluminum. A simple model for the cutting performance has been very successful in predicting the cutting sped and depth for most of these materials. Different assumptions of this model produce very little effect on the model predictions at high cutting speeds an a small difference at very slow cutting speeds. Additional physical effects such as the effects of vaporization, which can be significant at slow cutting speeds when cutting very thick sections, is incorporated into the model. This paper demonstrates how various assumptions within the derivation of the model can lead to different forms of the scaling law.

Latham, William P.; Kar, Aravinda

2000-01-01

278

Supplemental Oxygen (Oxygen Therapy)  

MedlinePLUS

... There are three ways oxygen therapy is supplied: Compressed oxygen gas and liquid oxygen are two ways to have oxygen delivered to the home. Oxygen gas is stored in tanks or cylinders of steel or aluminum. These tanks ...

279

Regulation of manganese peroxidase gene transcription by hydrogen peroxide, chemical stress, and molecular oxygen  

SciTech Connect

The expression of manganese peroxidase (MnP) in nitrogen-limited cultures of the lignin-degrading fungus Phanerochaete chrysosporium is regulated at the level of gene transcription by H{sub 2}O{sub 2} and various chemicals, including ethanol, sodium arsenite, and 2,4-dichlorophenol, as well as by Mn(II) and heat shock. Northern (RNA) blot analysis demonstrates that the addition of 1.0 mM H{sub 2}O{sub 2} to 5-day-old cultures grown in the absence of Mn results in the appearance of mnp mRNA within 15 min. Higher levels of mnp mRNA are obtained with simultaneous induction by Mn and H{sub 2}O{sub 2} than with H{sub 2}O{sub 2} alone. Although neither MnP activity nor associated protein is detectable in H{sub 2}O{sub 2}-induced cultures grown in the absence of Mn, simultaneous induction with Mn and H{sub 2}O{sub 2} results in a 1.6-fold increase in MnP activity compared with the MnP activity resulting resulting from Mn induction alone. In the presence of Mn, purging of low-nitrogen cultures with 100% O{sub 2}, in contrast to incubation under air, results in an increase in the accumulation of mnp mRNA and a 13-fold increase in MnP activity on day 5. However, in contrast to the effects of H{sub 2}O{sub 2} and heat shock, O{sub 2} purging of Mn-deficient cultures results in negligible accumulation of mnp mRNA. 48 refs., 6 figs.

Li, D.; Alic, M.; Brown, J.A.; Gold, M.H. [Oregon Graduate Institute of Science and Technology, Portland, OR (United States)

1995-01-01

280

Municipal waste treatment by supracell flotation, chemical oxidation and STAR (sludge thickening and alum recovery) system. Technical research report 1985-86  

SciTech Connect

This report documents effectiveness of a Krofta Supracell Type 4 Clarifier installed at the Bangor, Maine, Pollution Abatement Facility for the treatment of primary effluent. It includes detailed theory, principles, and test results on the permanganate oxidation-reduction system and the sludge thickening and alum recovery system. Reductions of total suspended solids, chemical oxygen demand, and 5-day biological oxygen demand are presented.

Krofta, M.; Wang, L.K.

1986-10-22

281

Enhancement of chemically induced reactive oxygen species production and DNA damage in human SH-SY5Y neuroblastoma cells by 872 MHz radiofrequency radiation  

Microsoft Academic Search

The objective of the study was to investigate effects of 872MHz radiofrequency (RF) radiation on intracellular reactive oxygen species (ROS) production and DNA damage at a relatively high SAR value (5W\\/kg). The experiments also involved combined exposure to RF radiation and menadione, a chemical inducing intracellular ROS production and DNA damage. The production of ROS was measured using the fluorescent

Jukka Luukkonen; Pasi Hakulinen; Jorma Mäki-Paakkanen; Jukka Juutilainen; Jonne Naarala

2009-01-01

282

Synthesis of Yttrium BARIUM(2) COPPER(3) Oxygen (7-X) Superconducting Thin Films by Metalorganic Chemical Vapor Deposition  

NASA Astrophysics Data System (ADS)

Yttrium barium cuprate (YBCO) superconducting thin films have been synthesized by metalorganic chemical vapor deposition (MOCVD) on various substrates. The depositions were conducted in a vertical, high-speed rotating (0-2000 rpm) disk reactor which was designed and assembled by this purpose. The 2,2,6,6-tetramethyl-3,5-heptanedione metal chelates of Y, Ba, and Cu were used as precursors, which were transported by nitrogen carrier gas. Oxygen gas was introduced uniformly through the top of the reactor. The films were grown by three different processes. First, YBCO layers were deposited at 500^circ C on (100) YSZ and (100) SrTiO_3 . Post-deposition annealing treatments were performed in order to convert the materials to the superconducting phase. The observed morphologies and the superconducting transition temperatures depended on the annealing process. Films annealed at 980^circC for 18 min exhibited a smooth morphology and metallic characteristics, and had a very sharp transition width (<=q 2K), with onset and zero resistance values of 90 and 88K, respectively. Second, in situ growth of YBCO thin films was performed at a temperature of 800 ^circC. After deposition, the films were cooled down at a rate of 5^circ C/min under 1 atm of oxygen. X-ray diffraction data showed the films to be highly oriented with the c -axis perpendicular to the plane of the substrate. Four -point resistance measurement yielded T_ {c}(R=O) at 91.8K (Delta T_{c} = 2.2K) and 85K (DeltaT_ {c} = 7K) on (100) YSZ and (100) MgO substrates, respectively. Finally, dense YBCO thin films with mirror-like surfaces and well-developed c-axis textures were prepared in situ at a substrate temperature as low as 570^circC by plasma -enhanced MOCVD (PE-MOCVD). Nitrous oxide was remotely activated by a microwave discharge, and transported to the surface of the growing film as atomic oxygen. The films deposited on (100) SrTiO_3 and (100) YSZ attained zero resistance at 72K without further processing. The results of this study indicate that low -temperature in situ fabrication of high-quality high-T _{c} superconducting oxide films by PE-MOCVD is a very attractive thin-film deposition process for the technology of superconducting devices.

Noh, Daniel Dong-Wook

283

Effect of oxygen and lipid supplementation on the volatile composition of chemically defined medium and Chardonnay wine fermented with Saccharomyces cerevisiae.  

PubMed

Oxygen or lipids are required to complete stressful alcoholic fermentation. Lack of these nutrients can inhibit sugar uptake and growth, which leads to incomplete or 'stuck' fermentation. Oxygen or lipids supplementation not only restores yeast fermentative activity and also affects formation of yeast volatile metabolites. To clarify the effect of oxygen and lipid supplementation on the formation of flavour active metabolites during wine fermentation, we evaluated the addition of these two nutrients to chemically defined grape juice and filter clarified Chardonnay must. Lipid addition increased the concentration of esters, higher alcohols and volatile acids, whereas oxygen increased the concentration of higher alcohols and altered the proportion of acetate to ethyl esters and the proportion of branch-chain acids to medium-chain fatty acids. Combined addition of lipids and oxygen showed an additive effect on concentration of higher alcohols whereas oxygen suppressed the enhancing effect of lipids on formation of esters and volatile acids. Our results demonstrate the potential of lipid and oxygen supplementation for the manipulation of wine aroma in white wine fermentation. PMID:22980883

Varela, C; Torrea, D; Schmidt, S A; Ancin-Azpilicueta, C; Henschke, P A

2012-07-15

284

LASERS: Self-initiating volume discharge in iodides used for producing atomic iodine in pulsed chemical oxygen — iodine lasers  

NASA Astrophysics Data System (ADS)

A volume self-sustained discharge (VSD) in iodides (C3H7I, C4H9I) and in their mixtures with SF6, N2, and O2 in the presence of small-scale inhomogeneities on the cathode surface is shown to develop in the form of a self-initiating volume discharge (SIVD), i.e., a volume discharge without any preionisation including discharge gaps with a strong edge enhancement of the electric field. Additions of SF6 or N2 to the iodides improves the stability and homogeneity of the SIVD, while adding up to 300 % (relative to the partial iodide pressure) of O2 to these mixtures has only an insignificant effect on the discharge stability. The possibility of SIVD initiation was modelled experimentally in a 1.5-L discharge volume. For the C4H9I:O2:SF6=0.083:0.25:0.67 mixture at a pressure of 72 Torr, the specific energy input into the discharge plasma ranged up to 130 J L-1 in this geometry. A conclusion was drawn that the SIVD is promising for the production of atomic iodine in the pulsed and repetitively pulsed operating regimes of a chemical oxygen — iodine laser.

Belevtsev, A. A.; Kazantsev, S. Yu; Saifulin, A. V.; Firsov, K. N.

2003-06-01

285

Chemical and structural status of copper associated with oxygenic and anoxygenic phototrophs and heterotrophs: possible evolutionary consequences.  

PubMed

Copper adsorption on the surface and intracellular uptake inside the cells of four representative taxons of soil and aquatic micro-organisms: aerobic rhizospheric heterotrophs (Pseudomonas aureofaciens), anoxygenic (Rhodovulum steppense) and oxygenic (cyanobacteria Gloeocapsa sp. and freshwater diatoms Navicula minima) phototrophs were studied in a wide range of pH, copper concentration, and time of exposure. Chemical status of adsorbed and assimilated Cu was investigated using in situ X-ray absorption spectroscopy. In case of adsorbed copper, XANES spectra demonstrated significant fractions of Cu(I) likely in the form of tri-coordinate complexes with O/N and/or S ligands. Upon short-term reversible adsorption at all four studied micro-organisms' cell surface, Cu(II) is coordinated by 4.0 ± 0.5 planar oxygens at an average distance of 1.97 ± 0.02 Å, which is tentatively assigned to the carboxylate groups. The atomic environment of copper incorporated into diatoms and cyanobacteria during long-term growth is similar to that of the adsorbed metal with slightly shorter distances to the first O/N neighbor (1.95 Å). In contrast to the common view of Cu status in phototrophic micro-organisms, XAFS failed to detect sulfur in the nearest atomic environment of Cu assimilated by freshwater plankton (cyanobacteria) and periphyton (diatoms). The appearance of S in Cu 1st coordination shell at 2.27-2.32 Å was revealed only after long-term interaction of Cu with anoxygenic phototrophs (and Cu uptake by soil heterotrophs), suggesting Cu scavenging in the form of sulfhydryl, histidine/carboxyl or a mixture of carboxylate and sulfhydryl complexes. These new structural constraints suggest that adsorbed Cu(II) is partially reduced to Cu(I) already at the cell surface, where as intracellular Cu uptake and storage occur in the form of both Cu(I)-S linked proteins and Cu(II) carboxylates. Obtained results allow to better understand how, in the course of biological evolution, micro-organisms elaborated various mechanisms of Cu uptake and storage, from passive adsorption and uptake to active, protein-controlled surface reduction, and intracellular storage. PMID:22039921

Pokrovsky, O S; Pokrovski, G S; Shirokova, L S; Gonzalez, A G; Emnova, E E; Feurtet-Mazel, A

2011-10-31

286

Demanding Satisfaction  

ERIC Educational Resources Information Center

It was the kind of crisis most universities dread. In November 2006, a group of minority student leaders at Indiana University-Purdue University Indianapolis (IUPUI) threatened to sue the university if administrators did not heed demands that included providing more funding for multicultural student groups. This article discusses how this threat…

Oguntoyinbo, Lekan

2010-01-01

287

Demanding Satisfaction  

ERIC Educational Resources Information Center

|It was the kind of crisis most universities dread. In November 2006, a group of minority student leaders at Indiana University-Purdue University Indianapolis (IUPUI) threatened to sue the university if administrators did not heed demands that included providing more funding for multicultural student groups. This article discusses how this threat…

Oguntoyinbo, Lekan

2010-01-01

288

Demand Dispatch  

Microsoft Academic Search

In this article we touch on some background requirements for demand dispatch and how the Internet can be used for communication and control. In addition, we review some of the basics of the operation of the electric power grid. We show how loads that meet the communication and control requirements can be aggregated and dispatched-turned on or off-to help manage

Alec Brooks; Ed Lu; Dan Reicher; Charles Spirakis; Bill Weihl

2010-01-01

289

Effect of support on reactivity and selectivity of Ni-based oxygen carriers for chemical-looping combustion  

Microsoft Academic Search

Different Ni-based oxygen carriers were prepared by dry impregnation using ?-Al2O3 as support. The reactivity, selectivity during methane combustion, attrition rate and agglomeration behavior of the oxygen carriers were measured and analyzed in a thermogravimetric analyzer and in a batch fluidized bed during multi-cycle reduction–oxidation tests.Ni-based oxygen carriers prepared on ?-Al2O3 showed low reactivity and low methane combustion selectivity to

Pilar Gayán; Luis F. de Diego; Francisco García-Labiano; Juan Adánez; Alberto Abad; Cristina Dueso

2008-01-01

290

Syngas combustion characteristics of four oxygen carrier particles for chemical-looping combustion in a batch fluidized bed reactor  

Microsoft Academic Search

Syngas combustion characteristics of oxygen carrier particles have been investigated. Experiments were performed on four oxygen\\u000a carrier particles in a fluidized bed reactor. All four oxygen carrier particles showed high gas conversion, high CO2 selectivity, and low CO concentration in the reducer and very low NOx (NO, NO2, N2O) emissions in the oxidizer. Moreover, all particles showed good regeneration ability

Ho-Jung Ryu; Dowon Shun; Dal-Hee Bae; Moon-Hee Park

2009-01-01

291

Low-oxygen and chemical kinetic constraints on the geochemical niche of neutrophilic iron(II) oxidizing microorganisms  

NASA Astrophysics Data System (ADS)

Neutrophilic iron oxidizing bacteria (FeOB) must actively compete with rapid abiotic processes governing Fe(II) oxidation and as a result have adapted to primarily inhabit low-O 2 environments where they can more successfully compete with abiotic Fe(II) oxidation. The spatial distribution of these microorganisms can be observed through the chemical gradients they affect, as measured using in situ voltammetric analysis for dissolved Fe(II), Fe(III), O 2, and FeS (aq). Field and laboratory determination of the chemical environments inhabited by the FeOB were coupled with detailed kinetic competition studies for abiotic and biotic oxidation processes using a pure culture of FeOB to quantify the geochemical niche these organisms inhabit. In gradient culture tubes, the maximum oxygen levels, which were associated with growth bands of Sideroxydans lithotrophicus (ES-1, a novel FeOB), were 15-50 ?M. Kinetic measurements made on S. lithotrophicus compared biotic/abiotic (killed control) Fe oxidation rates. The biotic rate can be a significant and measurable fraction of the total Fe oxidation rate below O 2 concentrations of approximately 50 ?M, but biotic Fe(II) oxidation (via the biotic/abiotic rate comparison) becomes difficult to detect at higher O 2 levels. These results are further supported by observations of conditions supporting FeOB communities in field settings. Variablity in cell densities and cellular activity as well as variations in hydrous ferrous oxide mineral quantities significantly affect the laboratory kinetic rates. The microbial habitat (or geochemical niche) where FeOB are active is thus largely controlled by the competition between abiotic and biotic kinetics, which are dependent on Fe(II) concentration, P O2, temperature and pH in addition to the surface area of hydrous ferric oxide minerals and the cell density/activity of FeOB. Additional field and lab culture observations suggest a potentially important role for the iron-sulfide aqueous molecular cluster, FeS (aq), in the overall cycling of iron associated with the environments these microorganisms inhabit.

Druschel, Gregory K.; Emerson, David; Sutka, R.; Suchecki, P.; Luther, George W., III

2008-07-01

292

Kinetic-fluid dynamics modeling of I{sub 2} dissociation in supersonic chemical oxygen-iodine lasers  

SciTech Connect

The mechanism of I{sub 2} dissociation in supersonic chemical oxygen-iodine lasers (COILs) is studied applying kinetic-fluid dynamics modeling, where pathways involving the excited species I{sub 2}(X {sup 1}SIGMA{sub g}{sup +},10<=v<25), I{sub 2}(X {sup 1}SIGMA{sub g}{sup +},25<=v<=47), I{sub 2}(A{sup '} {sup 3}PI{sub 2u}), I{sub 2}(A {sup 3}PI{sub 1u}), O{sub 2}(X {sup 3}SIGMA{sub g}{sup -},v), O{sub 2}(a {sup 1}DELTA{sub g},v), O{sub 2}(b {sup 1}SIGMA{sub g}{sup +},v), and I({sup 2}P{sub 1/2}) as intermediate reactants are included. The gist of the model is adding the first reactant and reducing the contribution of the second as compared to previous models. These changes, recently suggested by Azyazov, et al. [J. Chem. Phys. 130, 104306 (2009)], significantly improve the agreement with the measurements of the gain in a low pressure supersonic COIL for all I{sub 2} flow rates that have been tested in the experiments. In particular, the lack of agreement for high I{sub 2} flow rates, which was encountered in previous models, has been eliminated in the present model. It is suggested that future modeling of the COIL operation should take into account the proposed contribution of the above mentioned reactants.

Waichman, K. [Department of Physics, NRCN, P.O. Box 9001, Beer Sheva 89140 (Israel); Barmashenko, B. D.; Rosenwaks, S. [Department of Physics, Ben-Gurion University of the Negev, Beer Sheva 84105 (Israel)

2009-09-15

293

Oxygenated volatile organic chemicals in the oceans: Inferences and implications based on atmospheric observations and air-sea exchange models  

NASA Astrophysics Data System (ADS)

Airborne measurements of oxygenated volatile organic chemicals (OVOC), OH free radicals, and tracers of pollution were performed over the Pacific during Winter/Spring of 2001. We interpret atmospheric observations of acetaldehyde, propanal, methanol, and acetone with the help of a global 3-D model and an air-sea exchange model to assess their oceanic budgets. We infer that surface waters of the Pacific are greatly supersaturated with acetaldehyde and propanal. Bulk surface seawater concentration of 7 nM (10-9 mol L-1) and 2 nM and net fluxes of 1.1 × 10-12 g cm-2 s-1 and 0.4 × 10-12 g cm-2 s-1 are calculated for acetaldehyde and propanal, respectively. Large surface seawater concentrations are also estimated for methanol (100 nM) and acetone (10 nM) corresponding to an under-saturation of 6% and 14%, and a deposition velocity of 0.08 cm s-1 and 0.10 cm s-1, respectively. These data imply a large oceanic source for acetaldehyde and propanal, and a modest sink for methanol and acetone. Assuming a 50-100 meter mixed layer, an extremely large oceanic reservoir of OVOC, exceeding the atmospheric reservoir by an order of magnitude, can be inferred to be present. Available seawater data are both preliminary and extremely limited but indicate rather low bulk OVOC concentrations and provide no support for the existence of a large oceanic reservoir. We speculate on the causes and implications of these findings.

Singh, H. B.; Tabazadeh, A.; Evans, M. J.; Field, B. D.; Jacob, D. J.; Sachse, G.; Crawford, J. H.; Shetter, R.; Brune, W. H.

2003-08-01

294

Oxygen Abundances in Nearby FGK Stars and the Galactic Chemical Evolution of the Local Disk and Halo  

NASA Astrophysics Data System (ADS)

Atmospheric parameters and oxygen abundances of 825 nearby FGK stars are derived using high-quality spectra and a non-local thermodynamic equilibrium analysis of the 777 nm O I triplet lines. We assign a kinematic probability for the stars to be thin-disk (P 1), thick-disk (P 2), and halo (P 3) members. We confirm previous findings of enhanced [O/Fe] in thick-disk (P 2 > 0.5) relative to thin-disk (P 1 > 0.5) stars with [Fe/H] <~ -0.2, as well as a "knee" that connects the mean [O/Fe]-[Fe/H] trend of thick-disk stars with that of thin-disk members at [Fe/H] >~ -0.2. Nevertheless, we find that the kinematic membership criterion fails at separating perfectly the stars in the [O/Fe]-[Fe/H] plane, even when a very restrictive kinematic separation is employed. Stars with "intermediate" kinematics (P 1 < 0.7, P 2 < 0.7) do not all populate the region of the [O/Fe]-[Fe/H] plane intermediate between the mean thin-disk and thick-disk trends, but their distribution is not necessarily bimodal. Halo stars (P 3 > 0.5) show a large star-to-star scatter in [O/Fe]-[Fe/H], but most of it is due to stars with Galactocentric rotational velocity V < -200 km s-1 halo stars with V > -200 km s-1 follow an [O/Fe]-[Fe/H] relation with almost no star-to-star scatter. Early mergers with satellite galaxies explain most of our observations, but the significant fraction of disk stars with "ambiguous" kinematics and abundances suggests that scattering by molecular clouds and radial migration have both played an important role in determining the kinematic and chemical properties of solar neighborhood stars.

Ramírez, I.; Allende Prieto, C.; Lambert, D. L.

2013-02-01

295

A quality-control method for physical and chemical monitoring data. Application to dissolved oxygen levels in the river Loire (France)  

Microsoft Academic Search

A quality-control method is proposed for examining continuous physical and chemical measurements, including temperature, dissolved oxygen, pH and electrical conductivity. Firstly, measurement consistency is evaluated by various modelling approaches: internal series structure, inter-variable relations or relations with external variables, spatial coherence and deterministic models. Secondly, outliers or systematic errors are detected using classical statistical tests. The method was evaluated for

F. Moatar; J. Miquel; A. Poirel

2001-01-01

296

Chemical kinetics modelling of a decaying SF6 arc plasma in the presence of a solid organic insulator, copper, oxygen and water  

Microsoft Academic Search

The composition variations occurring in decaying SF6 arc plasmas in the presence of atoms released from the vaporization of organic insulators (e.g. Teflon, polyethylene, polypropylene, megelit, nylon), copper, oxygen and water were studied between 12 000 K and 300 K by means of a chemical kinetics model. From the results obtained at 300 K and a pressure of 101.3 kPa:

I. Coll; A. M. Casanovas; L. Vial; A. Gleizes; J. Casanovas

2000-01-01

297

Co – Ni \\/ Al 2 O 3 oxygen carrier for fluidized bed chemical-looping combustion: Desorption kinetics and metal–support interaction  

Microsoft Academic Search

This study was aimed at developing a suitable oxygen carrier for fluidized bed chemical-looping combustion (CLC) processes. To this end a Co promoted Co–Ni\\/Al2O3 carrier material was synthesized and evaluated. The reactivity of the solid carrier material was assessed by investigating the energetics and kinetics of metal–support interaction using temperature programmed H2 desorption technique. The estimated activation of energy of

M. M. Hossain; K. E. Sedor; H. I. de Lasa

2007-01-01

298

Effect of hydrogen sulfide on chemical looping combustion of coal-derived synthesis gas over bentonite-supported metal-oxide oxygen carriers  

Microsoft Academic Search

The effect of hydrogen sulfide (HS) on the chemical looping combustion of coal-derived synthesis gas with bentonite-supported metal oxides - such as iron oxide, nickel oxide, manganese oxide, and copper oxide - was investigated by thermogravimetric analysis, mass spectrometry, and X-ray photoelectron spectroscopy (XPS). During the reaction with synthesis gas containing HS, metal-oxide oxygen carriers were first reduced by carbon

Hanjing Tian; Thomas Simonyi; James Poston; Ranjani Siriwardane

2009-01-01

299

Technical Note: Performance of Chemical Ionization Reaction Time-of-Flight Mass Spectrometry (CIR-TOF-MS) for the measurement of atmospherically significant oxygenated volatile organic compounds  

Microsoft Academic Search

The performance of a new chemical ionization re- action time-of-flight mass spectrometer (CIR-TOF-MS) util- ising the environment chamber SAPHIR (Simulation of At- mospheric Photochemistry In a large Reaction Chamber- Forschungzentrum Julich, Germany) is described. The work took place as part of the ACCENT (Atmospheric Composi- tion and Change the European NeTwork for excellence) sup- ported oxygenated volatile organic compound (OVOC)

K. P. Wyche; R. S. Blake; A. M. Ellis; P. S. Monks; T. Brauers; R. Koppmann; E. C. Apel

2007-01-01

300

Technical Note: Performance of Chemical Ionization Reaction Time-of-Flight Mass Spectrometry (CIR-TOF-MS) for the measurement of atmospherically significant oxygenated volatile organic compounds  

Microsoft Academic Search

The performance of a new chemical ionization reaction time-of-flight mass spectrometer (CIR-TOF-MS) utilising the environment chamber SAPHIR (Simulation of Atmospheric Photochemistry In a large Reaction Chamber- Forschungzentrum Jülich, Germany) is described. The work took place as part of the ACCENT (Atmospheric Composition and Change the European NeTwork for excellence) supported oxygenated volatile organic compound (OVOC) measurement intercomparison during January 2005.

K. P. Wyche; R. S. Blake; A. M. Ellis; P. S. Monks; T. Brauers; R. Koppmann; E. C. Apel

2007-01-01

301

Performance of Chemical Ionization Reaction Time-of-Flight Mass Spectrometry (CIR-TOF-MS) for the measurement of atmospherically significant oxygenated volatile organic compounds  

Microsoft Academic Search

The performance of a new chemical ionization reaction time-of-flight mass spectrometer (CIR-TOF-MS) utilising the environment chamber SAPHIR (Simulation of Atmospheric Photochemistry In a large Reaction Chamber - Forschungzentrum Jülich, Germany) is described. The work took place as part of the ACCENT (Atmospheric Composition and Change the European NeTwork for excellence) supported oxygenated volatile organic compound (OVOC) measurement intercomparison during January

K. P. Wyche; R. S. Blake; A. M. Ellis; P. S. Monks; T. Brauers; R. Koppmann; E. Apel

2006-01-01

302

Isomer-specific determination of hexachlorodibenzo-p-dioxins by oxygen negative chemical ionization mass spectrometry, gas chromatography, and high-pressure liquid chromatography  

Microsoft Academic Search

All ten hexachlorodibenzo-p-dioxin (HCDD) isomers, prepared by micropyrolysis of chlorophenates, were studied by using mass spectrometry, gas chromatography, and high-pressure liquid chromatography. Of several ionization modes studied, oxygen negative chemical ionization was the most suitable for isomer identification. This technique enabling isomer specific identification to be carried out was applied to hexachlorodioxin impurities in pentachlorophenol samples and detected small amounts

Walter F. Miles; Narine P. Gurprasad; Greg P. Malis

1985-01-01

303

A record of hypolimnetic oxygen conditions in a temperate multi-depression lake from chemical evidence and chronomid remains  

Microsoft Academic Search

A multiproxy paleolimnological study of Douglas Lake, Michigan, was undertaken to elucidate the history of productivity and oxygen depletion in three basins of this multi-depression lake. Indicators investigated in three dated cores included chlorophyll a, Fe and Mn stratigraphy, and fossil chironomid assemblages. The coring sites were chosen to correspond to modern studies of oxygen depletion rates, and to determine

Donna R. Francis

2001-01-01

304

Effect of nickel loading on hydrogen production and chemical oxygen demand (COD) destruction from glucose oxidation and gasification in supercritical water  

Microsoft Academic Search

Gasification and partial oxidation of 0.25 molar glucose solution was conducted over different metallic nickel (Ni) loadings (7.5, 11, and 18wt%) on different catalyst supports (?-Al2O3 and ?-Al2O3) in supercritical water. Experiments were carried out at three different temperatures (T) of 400, 450, and 500°C at constant pressure of 28MPa and a 30min reaction time (t). For comparison, some experiments

Emhemmed A. Youssef; Muhammad B. I. Chowdhury; George Nakhla; Paul Charpentier

2010-01-01

305

Biodegradation of aromatic hydrocarbons by Haloarchaea and their use for the reduction of the chemical oxygen demand of hypersaline petroleum produced water  

Microsoft Academic Search

Ten halophilic Archaea (Haloarchaea) strains able to degrade aromatic compounds were isolated from five hypersaline locations; salt marshes in the Uyuni salt flats in Bolivia, crystallizer ponds in Chile and Cabo Rojo (Puerto Rico), and sabkhas (salt flats) in the Persian Gulf (Saudi Arabia) and the Dead Sea (Israel and Jordan). Phylogenetic identification of the isolates was determined by 16S

Maricy R. L. Bonfá; Matthew J. Grossman; Encarnacion Mellado; Lucia R. Durrant

2011-01-01

306

Nitrogen and Oxygen Isotopic Detection of Nitrate in Seawater by Chemical Conversion of Nitrate to Nitrous Oxide  

NASA Astrophysics Data System (ADS)

A fast, easy, and reliable method for nitrogen and oxygen isotopic detection of nitrate would be beneficial to many in the biogeochemical society. Here we present a novel method capable of natural isotopic detection in the nM range. In addition to a fast analysis time (batch preparation in less than one hour for nitrogen isotopes), this method is capable of very low blanks (less than 1 nanomole) with sample precision of 0.2 permil for nitrogen and 0.5 permil for oxygen. The first step of the method is reduction of nitrate to nitrite by use of either spongy cadmium or UV light. UV light reduction has the advantage of a short reaction time (13 minutes), but is not capable of oxygen isotope analysis due to exchange with water. Reduction using spongy cadmium retains the oxygen isotopic signature, but requires up to 3 hours to react. Both reactions are non-fractionating with respect to nitrogen. The next step is the reduction of nitrite to nitrous oxide using either hydroxylamine or azide. The hydroxylamine has the advantage of being nontoxic, but the reaction time is 2 hours and oxygen is exchanged with water. The azide-nitrite reaction is complete in only 3 minutes and retains both nitrogen and oxygen isotopes of nitrate. The produced nitrous oxide is then purged and trapped in liquid nitrogen, then released into a capillary GC column connected to an isotope ratio mass spectrometer.

McIlvin, M.; Altabet, M.

2003-12-01

307

Reduction kinetics of Cu-, Ni-, and Fe-based oxygen carriers using syngas (CO + H{sub 2}) for chemical-looping combustion  

SciTech Connect

The reactivity of three Cu-, Fe-, and Ni-based oxygen carriers to be used in a chemical-looping combustion (CLC) system using syngas as fuel has been analyzed. The oxygen carriers exhibited high reactivity during reduction with fuel gases present in syngas (H{sub 2} and CO), with average values in the range 8-30% min{sup -1}. No effect of the gas products (H{sub 2}O, CO{sub 2}) on the reduction reaction rate was detected. The kinetic parameters of reaction with H{sub 2} and CO have been determined by thermogravimetric analysis. The grain model with spherical or platelike geometry in the grain was used for the kinetic determination, in which the chemical reaction controlled the global reaction rate. The activation energies determined for these reactions were low, with values ranging from 14 to 33 kJ mol{sup -1}. The reaction order depended on the reacting gas, and values from 0.5 to 1 were found. Moreover, the reactivity of the oxygen carriers when both H{sub 2} and CO are simultaneously present in the reacting gases has been analyzed, both at atmospheric and pressurized conditions. For the Cu- and Fe-based oxygen carriers, the reaction rate of the oxygen carrier with syngas corresponded to the addition of the reaction rates for the individual fuel gases, H{sub 2} and CO. For the Ni-based oxygen carrier, the reaction rate was that corresponding to the fuel gas that reacted faster with the oxygen carrier at the reacting conditions (fuel concentration, temperature, and pressure). The consequences of the behavior of the reaction of syngas and the water-gas shift (WGS) equilibrium on the design of the fuel reactor of a CLC system have been analyzed. A preliminary estimation of the solids inventory for the use of syngas in the fuel reactor of a CLC system gave values in the range of 19-34 kg MW{sup -1} when the WGS equilibrium was considered to be instantaneous. 8 figs., 4 tabs.

Alberto Abad; Francisco Garcia-Labiano; Luis F. de Diego; Pilar Gayn; Juan Adnez [Instituto de Carboquimica (CSIC), Zaragoza (Spain). Department of Energy and Environment

2007-08-15

308

Reactivity deterioration of NiO/Al{sub 2}O{sub 3} oxygen carrier for chemical looping combustion of coal in a 10 kW{sub th} reactor  

SciTech Connect

A relatively long-term experiment for chemical looping combustion of coal with NiO/Al{sub 2}O{sub 3} oxygen carrier was carried out in a 10 kW{sub th} continuous reactor of interconnected fluidized beds, and 100 h of operation was reached with the same batch of the oxygen carrier. The reactivity deterioration of the oxygen carriers was present during the experimental period. The reactivity deterioration of reacted oxygen carriers at different experimental stages was evaluated using X-ray diffraction (XRD), scanning electron microscope (SEM), and X-ray fluorescence spectrometer. SEM analysis showed no significant change in the morphology of the nickel-based oxygen carrier at the fuel reactor temperature {<=}940 C, but loss of surface area and porosity of reacted oxygen carriers was observed when the fuel reactor temperature exceeded 960 C. The results show that the sintering effect have mainly contributed to the reactivity deterioration of reacted oxygen carriers in the CLC process for coal, while the effects of coal ash and sulfur can be ignored. The oxidization of reduced oxygen carrier with air was an intensive exothermic process, and the high temperature of oxygen carrier particles led to sintering on the surface of oxygen carrier particles in the air reactor. Attention must be paid to control the external circulation of oxygen carrier particles in the interconnected fluidized beds in order to efficiently transport heat from the air reactor to the fuel reactor, and reduce the temperature of oxygen carrier particles in the air reactor. Improvement of reactivity deterioration of reacted oxygen carriers was achieved by the supplement of steam into the fuel reactor. Nevertheless, NiO/Al{sub 2}O{sub 3} is still one of the optimal oxygen carriers for chemical looping combustion of coal if the sintering of oxygen carrier is minimized at the suitable reactor temperature. (author)

Shen, Laihong; Wu, Jiahua; Gao, Zhengping; Xiao, Jun [Thermoenergy Engineering Research Institute, Southeast University, 2 Sipailou, Nanjing 210096 (China)

2009-07-15

309

Investigation of chemical looping combustion by solid fuels. 2. redox reaction kinetics and product characterization with coal, biomass, and solid waste as solid fuels and CuO as an oxygen carrier  

Microsoft Academic Search

This paper is the second in a series of two on the investigation of the chemical looping combustion (CLC) of solid fuels. The first paper put forward the concept of the CLC of solid fuels using a circulating fluidized bed as a reactor and Cu-CuO as the oxygen carrier, which was based on an analysis of oxygen transfer capability, reaction

Yan Cao; Bianca Casenas; Wei-Ping Pan

2006-01-01

310

Spatial and seasonal evolution of dissolved oxygen and nutrients in the Southern Levantine Basin (Eastern Mediterranean Sea): chemical characterization of the water masses and inferences on the N : P ratios  

Microsoft Academic Search

The spatial and seasonal variability of nutrients and dissolved oxygen concentrations as well as the chemical characterization of the different water masses of the Southern Levantine Basin were determined in detail. In summer, the upper 150m of the water body was stratified and the cross basin distribution of dissolved oxygen and nutrients was fairly constant. Surficial waters were saturated with

Nurit Kress; Barak Herut

2001-01-01

311

Preliminary investigation of the supply of chemical species to an aqueous solution using a hydrogen-oxygen flame.  

PubMed

A new method of supplying radical species to aqueous solutions using a hydrogen-oxygen flame is investigated. When a hydrogen-oxygen flame is directed on the surface of an aqueous solution, hydroxyl radicals (*OH) produced in the flame are extracted into the aqueous phase. The presence of *OH in the aqueous solution was confirmed by electron paramagnetic resonance with spin trapping using 5,5-dimethyl-1-pyrroline-N-oxide. The extraction of *OH into the aqueous solution was monitored using a quantitative analysis of hydrogen peroxide (H2O2). The effects of the hydrogen and oxygen gas flow rates, hydrogen/oxygen ratio, and atmosphere on H2O2 formation were studied. When the hydrogen-oxygen flame blew on a phosphate buffer solution (pH 6.7) under an Ar atmosphere, the concentration of H2O2 increased with the blowing time of the flame and the flow rate of hydrogen gas. Under air, nitrate and nitrite ions were formed in the aqueous phase in addition to H2O2, and the H2O2 concentration was lower than that under argon. The application of this new method to an aqueous solution of Cu(II)-ethylenediaminetetraacetic acid (EDTA) caused a remarkable decrease in the concentration of Cu(II)-EDTA and total organic carbon. PMID:16124325

Uchida, Miho; Sogabe, Takahiro; Ikoma, Tadaaki; Okuwakit, Akitsugu

2005-08-01

312

CONTROL OF LASER RADIATION PARAMETERS: Enhancement of the efficiency and control of emission parameters of an unstable-resonator chemical oxygen—iodine laser  

NASA Astrophysics Data System (ADS)

The outlook is considered for the development of a high-power supersonic flowing chemical oxygen—iodine laser operating as an amplifier and controlled by radiation from a master oscillator by using an unstable resonator with a hole-coupled mirror. The influence of the seed radiation intensity, the coupling-hole diameter, the active-medium length, and the magnification factor on the parameters of laser radiation is analysed. It is shown that the use of such resonators is most advisable in medium-power oxygen—iodine lasers for which classical unstable resonators are inefficient because of their low magnification factors. The use of unstable resonators with a hole-coupled mirror and injection provides the control of radiation parameters and a considerable increase in the output power and brightness of laser radiation.

Boreisho, A. S.; Lobachev, V. V.; Savin, A. V.; Strakhov, S. Yu; Trilis, A. V.

2007-07-01

313

Chemical diffusion and oxygen exchange of La0.6Sr0.4Co0.6Fe0.4O3-d  

Microsoft Academic Search

The transport parameters of La0.6Sr0.4Co0.6Fe0.4O3?? were determined by electrical conductivity relaxation and high temperature coulometric titration experiments. The experimental response curves were analyzed in the frequency domain. The results obtained by both methods were in good agreement. The chemical diffusion coefficients measured at temperatures of 923–1255 K and oxygen partial pressures of 0.03–1 bar O2, vary between 10?6–5×10?5 cm2 s?1.

Elshof ten J. E; M. H. R. Lankhorst; H. J. M. Bouwmeester

1997-01-01

314

Chemical diffusion and oxygen exchange of La 0.6Sr 0.4Co 0.6Fe 0.4O 3? ?  

Microsoft Academic Search

The transport parameters of La0.6Sr0.4Co0.6Fe0.4O3?? were determined by electrical conductivity relaxation and high temperature coulometric titration experiments. The experimental response curves were analyzed in the frequency domain. The results obtained by both methods were in good agreement. The chemical diffusion coefficients measured at temperatures of 923–1255 K and oxygen partial pressures of 0.03–1 bar O2, vary between 10?6–5×10?5 cm2s?1. The

J. E. ten Elshof; M. H. R. Lankhorst; H. J. M. Bouwmeester

1997-01-01

315

PHYSICAL PROCESSES IN LASERS AND CONTROL OF LASER RADIATION PARAMETERS: Control of the duration of optical pulses from an oxygen-iodine chemical laser  

NASA Astrophysics Data System (ADS)

It is shown that long radiation pulses needed in applications of lasers in technology may be emitted efficiently by an oxygen-iodine chemical laser. Slow photolysis can increase the output pulse duration to approximately 1 ms while retaining a high efficiency. Calculations yield the dependence of the lasing characteristics on all the parameters of interest. It is demonstrated that at high active medium pressures (up to 100 Torr) and low iodine concentrations, the pulse duration may be regulated with a high specific output energy and a high photolysis efficiency.

Zagidullin, M. V.; Zaikin, A. P.; Igoshin, Valerii I.

1989-04-01

316

Deactivation rate of I{sub 2} molecules (X, v {>=} 30) in the medium of a chemical oxygen-iodine laser  

SciTech Connect

The effective deactivation rate constants are calculated for I{sub 2}(X) molecules at vibrational levels with v {>=} 30 colliding with N{sub 2} and O{sub 2} molecules in the medium of a chemical oxygen-iodine laser. The calculated constants (4x10{sup -12} cm{sup 3} s{sup -1} and 3x10{sup -12} cm{sup 3} s{sup -1}) are less by half plus than the corresponding constants found earlier in the paper of Lawrence et al., where the dissociation of I{sub 2} was neglected in calculations. (lasers, active media)

Pichugin, S Yu [Samara Branch of the P. N. Lebedev Physics Institute, Russian Academy of Sciences, Samara (Russian Federation)

2008-08-31

317

Chemical kinetics and reactive species in atmospheric pressure helium-oxygen plasmas with humid-air impurities  

NASA Astrophysics Data System (ADS)

In most applications helium-based plasma jets operate in an open-air environment. The presence of humid air in the plasma jet will influence the plasma chemistry and can lead to the production of a broader range of reactive species. We explore the influence of humid air on the reactive species in radio frequency (rf)-driven atmospheric-pressure helium-oxygen mixture plasmas (He-O2, helium with 5000 ppm admixture of oxygen) for wide air impurity levels of 0-500 ppm with relative humidities of from 0% to 100% using a zero-dimensional, time-dependent global model. Comparisons are made with experimental measurements in an rf-driven micro-scale atmospheric pressure plasma jet and with one-dimensional semi-kinetic simulations of the same plasma jet. These suggest that the plausible air impurity level is not more than hundreds of ppm in such systems. The evolution of species concentration is described for reactive oxygen species, metastable species, radical species and positively and negatively charged ions (and their clusters). Effects of the air impurity containing water humidity on electronegativity and overall plasma reactivity are clarified with particular emphasis on reactive oxygen species.

Murakami, Tomoyuki; Niemi, Kari; Gans, Timo; O'Connell, Deborah; Graham, William G.

2013-02-01

318

An upflow microaerobic sludge blanket reactor operating at high organic loading and low dissolved oxygen levels  

Microsoft Academic Search

The activated sludge process (ASP) has high operational costs due to the need for aeration at dissolved O2 (DO) levels of ?2 mg l?1 and high capital costs to construct large reactors due to a low organic loading [typically 1 kg chemical oxygen demand (COD) m?3 day?1]. A novel method for improving the energy use and treatment efficiency of the ASP via limited oxygenation (0.4 mg

Shaokui Zheng; Huijun Li; Cancan Cui

2011-01-01

319

Treatment of chemical mechanical polishing wastewater by electrocoagulation: system performances and sludge settling characteristics  

Microsoft Academic Search

Treatment of copper chemical mechanical polishing (CMP) wastewater from a semiconductor plant by electrocoagulation is investigated. The CMP wastewater was characterized by high suspended solids (SS) content, high turbidity (NTU), chemical oxygen demand (COD) concentration up to 500 mgl?1 and copper concentration up to 100 mgl?1. In the present study, electrocoagulation was employed to treat the CMP wastewater with an

Chen L. Lai; Sheng H. Lin

2004-01-01

320

The Interconversion of Electrical and Chemical Energy: The Electrolysis of Water and the Hydrogen-Oxygen Fuel Cell.  

ERIC Educational Resources Information Center

Discusses some of the drawbacks of using a demonstration of the electrolysis of water to illustrate the interconversion between electrical and chemical energy. Illustrates a simple apparatus allowing demonstration of this concept while overcoming these drawbacks. (CW)

Roffia, Sergio; And Others

1988-01-01

321

The Interconversion of Electrical and Chemical Energy: The Electrolysis of Water and the Hydrogen-Oxygen Fuel Cell.  

ERIC Educational Resources Information Center

|Discusses some of the drawbacks of using a demonstration of the electrolysis of water to illustrate the interconversion between electrical and chemical energy. Illustrates a simple apparatus allowing demonstration of this concept while overcoming these drawbacks. (CW)|

Roffia, Sergio; And Others

1988-01-01

322

A Mössbauer and X-ray diffraction study of annites synthesized at different oxygen fugacities and crystal chemical implications  

Microsoft Academic Search

A refined set of Mössbauer parameters (isomer shifts, quadrupole splittings, Fe2+\\/Fe3+ ratios) and lattice parameters were obtained from annites synthesized hydrothermally at pressures between 3 and 5 kbars, temperatures ranging from 250 to 780° C and oxygen fugacities controlled by solid state buffers (NNO, QMF, IM, IQF). Mössbauer spectra showed Fe2+ and Fe3+ on both the M1 and the M2

G. J. Redhammer; A. Beran; E. Dachs; G. Amthauer

1993-01-01

323

Continuum and Quantum-Chemical Modeling of Oxygen Reduction on the Cathode in a Solid Oxide Fuel Cell  

Microsoft Academic Search

Solid oxide fuel cells (SOFCs) have several advantages over other types of fuels cells such as high-energy efficiency and\\u000a excellent fuel flexibility. To be economically competitive, however, new materials with extraordinary transport and catalytic\\u000a properties must be developed to dramatically improve the performance while reducing the cost. This article reviews recent\\u000a advancements in understanding oxygen reduction on various cathode materials

YongMan Choi; David S. Mebane; Jeng-Han Wang; Meilin Liu

2007-01-01

324

CARBON COATED (CARBONOUS) CATALYST IN EBULLATED BED REACTOR FOR PRODUCTION OF OXYGENATED CHEMICALS FROM SYNGAS\\/CO2  

Microsoft Academic Search

This report summarizes the work completed under DOE's Support of Advanced Fuel Research program, Contract No. DE-FG26-99FT40681. The contract period was October 2000 through September 2002. This R&D program investigated the modification of the mechanical strength of catalyst extrudates using Hydrocarbon Technologies, Inc. (HTI) carbon-coated catalyst technology so that the ebullated bed technology can be utilized to produce valuable oxygenated

Peizheng Zhou

2002-01-01

325

IDENTIFICATION OF MINOR OXYGEN HETEROCYCLIC COMPOUNDS OF CITRUS ESSENTIAL OILS BY LIQUID CHROMATOGRAPHY-ATMOSPHERIC PRESSURE CHEMICAL IONISATION MASS SPECTROMETRY  

Microsoft Academic Search

The oxygen heterocyclic compounds (coumarins, psoralens, and polymethoxylated flavones (PMFs)) present in citrus essential oils (lemon, mandarin, sweet orange, bitter orange, bergamot, grapefruit, and lime) were analysed by an HPLC-MS system equipped with an APcI source. The mass spectra obtained at different voltages of the “sample cone” have been used to build a library.Citrus essential oils have been analysed with

P. Dugo; L. Mondello; E. Sebastiani; R. Ottanà; G. Errante; G. Dugo

1999-01-01

326

Influence of chemical and physical properties of activated carbon powders on oxygen reduction and microbial fuel cell performance.  

PubMed

Commercially available activated carbon (AC) powders made from different precursor materials (coal, peat, coconut shell, hardwood, and phenolic resin) were electrochemically evaluated as oxygen reduction catalysts and tested as cathode catalysts in microbial fuel cells (MFCs). AC powders were characterized in terms of surface chemistry and porosity, and their kinetic activities were compared to carbon black and platinum catalysts in rotating disk electrode (RDE) tests. Cathodes using the coal-derived AC had the highest power densities in MFCs (1620 ± 10 mW m(-2)). Peat-based AC performed similarly in MFC tests (1610 ± 100 mW m(-2)) and had the best catalyst performance, with an onset potential of E(onset) = 0.17 V, and n = 3.6 electrons used for oxygen reduction. Hardwood based AC had the highest number of acidic surface functional groups and the poorest performance in MFC and catalysis tests (630 ± 10 mW m(-2), E(onset) = -0.01 V, n = 2.1). There was an inverse relationship between onset potential and quantity of strong acid (pKa < 8) functional groups, and a larger fraction of microporosity was negatively correlated with power production in MFCs. Surface area alone was a poor predictor of catalyst performance, and a high quantity of acidic surface functional groups was determined to be detrimental to oxygen reduction and cathode performance. PMID:23692057

Watson, Valerie J; Nieto Delgado, Cesar; Logan, Bruce E

2013-06-03

327

On interface properties of ultra-thin and very-thin oxide/a-Si:H structures prepared by oxygen based plasmas and chemical oxidation  

NASA Astrophysics Data System (ADS)

Amorphous hydrogenated silicon (a-Si:H) belongs still to most promising types of semiconductors for its utilization in fabrication of TFTs and thin film solar cell technology due to corresponding cheap a-Si:H-based device production in comparison with, e.g. crystalline silicon (c-Si) technologies. The contribution deals with both two important modes of preparation of very-thin and ultra-thin silicon dioxide films in the surface region of a-Si:H semiconductor (oxygen plasma sources and liquid chemical methods) and electrical, optical and structural properties of produced oxide/semiconductor structures, respectively. Dominant aim is focused on investigation of oxide/semiconductor interface properties and their comparison and evaluation from view of utilization of used technological modes in the nanotechnological industry. Following three basic types of oxygen plasma sources were used for the first time in our laboratories for treatments of surfaces of a-Si:H substrates: (i) inductively coupled plasma in connection with its applying at plasma anodic oxidation; (ii) rf plasma as the source of positive oxygen ions for plasma immersion ion implantation process; (iii) dielectric barrier discharge ignited at high pressures. The liquid chemical manner of formation SiO2/a-Si:H structures uses 68 wt% nitric acid aqueous solutions (i.e., azeotropic mixture with water). Their application in crystalline Si technologies has been presented with excellent results in the formation of ultra-thin SiO2/c-Si structures [H. Kobayashi, M. Asuha, H.I. Takahashi, J. Appl. Phys. 94 (2003) 7328]. Passivation of surface and interface states by liquid cyanide treatment is additional original technique applied after (or before) formation of almost all formed thin film/a-Si:H structures. Passivation process should be used if high-quality electronical parameters of devices can be reached.

Pin?ík, Emil; Kobayashi, Hikaru; Hajossy, Rudolf; Glesková, Helena; Takahashi, Masao; Jergel, Matej; Brunner, Róbert; Ortega, Luc; Ku?era, Michal; Krá?, Martin; Rusnák, Jaroslav

2007-06-01

328

Oxygen Sag and Stream Purification.  

ERIC Educational Resources Information Center

Presents a literature review of water quality related to oxygen sag and stream purification, covering publications of 1976-77. This review includes: (1) self-purification models; (2) oxygen demand; and (3) reaeration and oxygen transfer. A list of 60 references is also presented. (HM)

Neal, Larry; Herwig, Roy

1978-01-01

329

The story of oxygen.  

PubMed

The history of oxygen from discovery to clinical application for patients with chronic lung disease represents a long and storied journey. Within a relatively short period, early investigators not only discovered oxygen but also recognized its importance to life and its role in respiration. The application of oxygen to chronic lung disease, however, took several centuries. In the modern era, physiologists pursued the chemical nature of oxygen and its physiologic interaction with cellular metabolism and gas transport. It took brazen clinicians, however, to pursue oxygen as a therapeutic resource for patients with chronic lung disease because of the concern in the 20th century of the risks of oxygen toxicity. Application of ambulatory oxygen devices allowed landmark investigations of the long-term effects of continuous oxygen that established its safety and efficacy. Although now well established for hypoxic patients, many questions remain regarding the benefits of oxygen for varying severity and types of chronic lung disease. PMID:23271817

Heffner, John E

2013-01-01

330

Syngas combustion in a chemical-looping combustion system using an impregnated Ni-based oxygen carrier  

Microsoft Academic Search

Chemical-looping combustion (CLC) has emerged as a promising option for CO2 capture because this gas is inherently separated from the other flue gas components and thus no energy is expended for the separation. This technology would have some advantages if it could be adapted for its use with coal as fuel. In this sense, a process integrated by coal gasification

Cristina Dueso; Francisco García-Labiano; Juan Adánez; Luis F. de Diego; Pilar Gayán; Alberto Abad

2009-01-01

331

Project Title: Modeling Corrosion in Oxygen Controlled LBE Systems with Coupling of Chemical Kinetics and Hydrodynamics - Phase Three  

Microsoft Academic Search

The proposed work will combine chemical kinetics and hydrodynamics in target and test-loop lead-bismuth eutectic (LBE) systems to model system corrosion effects. This approach will result in a predicative tool that can be validated with corrosion test data, used to systematically design tests and interpret the results, and provide guidance for optimization in LBE system designs. The task includes two

Ning Li

332

Removal and fate of endocrine disruptors chemicals under lab-scale postreatment stage. Removal assessment using light, oxygen and microalgae.  

PubMed

The aim of this study was to assess the effect of light, oxygen and microalgae on micropollutants removal. The studied micropollutants were 4-(1,1,3,3-tetramethylbutyl)phenol (OP), technical-nonylphenol (t-NP), 4-n-nonylphenol (4-NP), Bisphenol-A (BPA). In order to study the effect of the three variables on the micropollutants removal, a factorial design was developed. The experiments were carried out in four batch reactors which treated the effluent of an anaerobic membrane bioreactor. The gas chromatography mass spectrometry was used for the measurement of the micropollutants. The results showed that light, oxygen and microalgae affected differently to the degradation ratios of each micropollutant. The results showed that under aerated conditions removal ratios higher than 91% were achieved, whereas for non-aerated conditions the removal ratios were between 50% and 80%, except for 4-NP which achieved removal ratios close to 100%. Besides, mass balance showed that the degradation processes were more important than the sorption processes. PMID:24096281

Abargues, M R; Ferrer, J; Bouzas, A; Seco, A

2013-09-19

333

Chemical Reactivity of Reduced TiO2(110): The dominant role of surface defects in oxygen chemisorption  

SciTech Connect

O2 chemisorption on reduced, rutile TiO2(110) with various concentrations of oxygen vacancies (Ov) and bridging hydroxyls (OHb) is investigated with scanning tunneling microscopy, temperature programmed desorption and electron-stimulated desorption. On the annealed surface, 2 oxygen molecules can be chemisorbed per Ov. The same amount of O2 chemisorbs on surfaces where each Ov is converted to two OHb’s by exposure to water (i.e. 1 O2 per OHb). Surfaces with few or no Ov’s or OHb’s can be created by exposing the hydroxylated surface to O2 at room temperature, and the amount of O2 that chemisorbs on these surfaces at low temperatures is only ~20% of the amount on the annealed (reduced) surface. In contrast, the amount of chemisorbed O2 increases by more than a factor of two when the OHb concentration is enhanced – without changing the concentration of sub-surface Ti interstitials. The results indicate that the reactivity of TiO2(110) is primarily controlled by the amount of electron-donating surface species such as Ov’s and/or OHb’s, and not Ti3+ interstitials.

Petrik, Nikolay G.; Zhang, Zhenrong; Du, Yingge; Dohnalek, Zdenek; Lyubinetsky, Igor; Kimmel, Gregory A.

2009-07-16

334

Oxygen transfer in membrane bioreactors treating synthetic greywater  

Microsoft Academic Search

Mass transfer coefficients (kLa) were studied in two pilot scale membrane bioreactors (MBR) with different setup configurations treating 200L\\/h of synthetic greywater with mixed liquor suspended solids' (MLSS) concentrations ranging from 4.7 to 19.5g\\/L. Besides the MLSS concentration, mixed liquor volatile suspended solids (MLVSS), total solids (TS), volatile solids (VS), chemical oxygen demand (COD) and anionic surfactants of the sludge

Jochen Henkel; Mladen Lemac; Martin Wagner; Peter Cornel

2009-01-01

335

STRUCTURAL FEATURES ASSOCIATED WITH DEGRADABLE AND PERSISTENT CHEMICALS  

EPA Science Inventory

A multivariate statistical method and a heuristic method were employed to examine the structural features associated with the persistence of degradation of 287 chemicals tested with the standard biochemical oxygen demand(BOD) procedure. The data base consisted of 196 'degradable'...

336

Parameters of an electric-discharge generator of iodine atoms for a chemical oxygen-iodine laser  

SciTech Connect

Laser-induced fluorescence is used for measuring the concentration of iodine molecules at the output of an electric-discharge generator of atomic iodine. Methyl iodide CH{sub 3}I is used as the donor of atomic iodine. The fraction of iodine extracted from CH{sub 3}I in the generator is {approx}50%. The optimal operation regimes are found in which 80%-90% of iodine contained in the output flow of the generator was in the atomic state. This fraction decreased during the iodine transport due to recombination and was 20%-30% at the place where iodine was injected into the oxygen flow. The fraction of the discharge power spent for dissociation was {approx}3%. (elements of laser setups)

Azyazov, V N; Vorob'ev, M V; Voronov, A I; Kupryaev, Nikolai V; Mikheev, P A; Ufimtsev, N I [Samara Branch of the P.N. Lebedev Physics Institute, Russian Academy of Sciences, Samara (Russian Federation)

2009-01-31

337

Low-oxygen and chemical kinetic constraints on the geochemical niche of neutrophilic iron(II) oxidizing microorganisms  

Microsoft Academic Search

Neutrophilic iron oxidizing bacteria (FeOB) must actively compete with rapid abiotic processes governing Fe(II) oxidation and as a result have adapted to primarily inhabit low-O2 environments where they can more successfully compete with abiotic Fe(II) oxidation. The spatial distribution of these microorganisms can be observed through the chemical gradients they affect, as measured using in situ voltammetric analysis for dissolved

Gregory K. Druschel; David Emerson; R. Sutka; P. Suchecki; George W. Luther

2008-01-01

338

Demand for ozone-depleting substances and hydrofluorocarbons estimated by a Tier 2 emission inventory model compared to top-down chemical consumption data for the US  

Microsoft Academic Search

In preparing inventories of ozone-depleting substance (ODS) substitutes, primarily hydrofluorocarbons, the US employs models consistent with Tier 2 methodologies from the 2006 IPCC Guidelines for National Greenhouse Gas Inventories. The model calculates chemical consumption and emissions for 60 sub-applications, which are aggregated to five application levels. So-called “bottom-up” models require data and assumptions regarding the sub-application industries, including number of

David S. Godwin

2012-01-01

339

A detailed chemical analysis of changes to bitumen produced by the in situ combustion process at the oxygen Wolf Lake Project, Alberta. Part 11; Whole oil samples  

SciTech Connect

The detailed chemical changes in bitumen brought about over a one year period by a in situ combustion process in an oil sands reservoir have been investigated. Relative to a core sample, the fireflood-produced oils exhibited a significant reduction in density and viscosity which began early in the production cycle. This behavior was correlated with a marked increase in material boiling in the naphtha and middle distillate ranges and a concomitant decrease in the residue cut. The sulfur and nitrogen contents in the produced oils decreased relative to the core sample. A reduction in the acid number of the produced oil samples was coupled with an increase in the oxygen content as the fireflood proceeded. In this paper the relationship between these changes and the dynamics of the in situ combustion process are discussed.

Alex, R.F.; Fuhr, B.; Reichert, C. (Alberta Research Council, Oil Sands and Hydrocarbon Recovery, Edmonton, Alberta T6H 5X2 (CA))

1992-01-01

340

Chemical diffusion of oxygen in dense, textured (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x}.  

SciTech Connect

Dense polycrystalline (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub y} specimens were fabricated by sinter forging. The specimens exhibited excellent phase purity and strong texture of c-axes, which were preferentially aligned parallel to the forging direction. The chemical diffusion coefficient of oxygen, {tilde D}, measured in pure O{sub 2} could be represented as {tilde D}{sub ab} {approx} 1.78 x 10{sup -3} exp(-0.96 eV/kT), where the subscript ab refers to diffusion within the a-b-plane. The measurements suggested that {tilde D}{sub ab} >> {tilde D}{sub c}, where the subscript c refers to diffusion in the c-direction.

Park, J.-H.; Goretta, K. C.; Murayama, N.; Energy Technology; National Industrial Research Inst. of Nagoya

1999-01-01

341

FUNDAMENTAL AREAS OF PHENOMENOLOGY (INCLUDING APPLICATIONS): Pulse Operation of Chemical Oxygen-Iodine Laser by Pulsed Gas Discharge with the Assistance of Spark Pre-ionization  

NASA Astrophysics Data System (ADS)

The continuous wavelength chemical oxygen-iodine laser can be turned into pulse operation mode in order to obtain high energy and high pulse power. We propose an approach to produce iodine atoms instantaneously by pulsed gas discharge with the assistance of spark pre-ionization to achieve the pulsed goal. The influence of spark pre-ionization on discharge homogeneity is discussed. Voltage-current characteristics are shown and discussed in existence of the pre-ionization capacitor and peaking capacitor. The spark pre-ionization and peaking capacitor are very helpful in obtaining a stable and homogeneous discharge. The lasing is achieved at the total pressure of 2.2-2.9kPa and single pulse energy is up to 180 mJ, the corresponding specific output energy is 1.0 J/L.

Li, Guo-Fu; Yu, Hai-Jun; Duo, Li-Ping; Jin, Yu-Qi; Wang, Jian; Sang, Feng-Ting; Fang, Ben-Jie; Wang, De-Zhen

2009-11-01

342

Degradation modes of austenitic and ferritic–martensitic stainless steels in He–CO–CO2 and liquid sodium environments of equivalent oxygen and carbon chemical potentials  

NASA Astrophysics Data System (ADS)

The objective of this work is to explore possible thermodynamic correlations between the degradation modes of austenitic and ferritic–martensitic alloys observed in high temperature He–CO–CO2 environments with oxygen and carbon chemical potentials equivalent to that in a liquid sodium environment containing 2–5 molppm oxygen and 0.02–0.2 molppm carbon at temperatures 500–700 °C. Two He–CO–CO2 environments (Pco/Pco2 = 1320, Pco = 1980 molppm, and Pco/Pco2 = 9, Pco = 13.5 molppm) were selected to test alloys NF616 and 316L at 700 and 850 °C. Upon exposure to He environments at 850 °C, 316L samples exhibited thick surface Cr2O3 scales and substantial internal oxidation; however at 700 °C no significant internal oxidation was observed. NF616 samples exhibited relatively thinner surface Cr2O3 scales compared to 316L samples at both temperatures. NF616 samples exposed to liquid sodium at 700 °C and He–Pco/Pco2 = 9 at 850 °C showed decarburization. No surface oxide formation was observed on the sample exposed to the Na environment. Results obtained from He exposure experiments provide insight into what may occur during long exposure times in a sodium environment.

Gulsoy, G.; Was, G. S.; Pawel, S. J.; Busby, J. T.

2013-10-01

343

Towards a better understanding of the origins, chemical composition and aging of oxygenated organic aerosols: case study of a Mediterranean industrialized environment, Marseille  

NASA Astrophysics Data System (ADS)

As part of the FORMES summer 2008 experiment, an Aerodyne compact time-of-flight aerosol mass spectrometer (cToF-AMS) was deployed at an urban background site in Marseille to investigate the sources and aging of organic aerosols (OA). France's second largest city and the largest port in the Mediterranean, Marseille, provides a locale that is influenced by significant urban industrialized emissions and an active photochemistry with very high ozone concentrations. Particle mass spectra were analyzed by positive matrix factorization (PMF2) and the results were in very good agreement with previous apportionments obtained using a chemical mass balance (CMB) approach coupled to organic markers and metals (El Haddad et al., 2011a). AMS/PMF2 was able to identify for the first time, to the best of our knowledge, the organic aerosol emitted by industrial processes. Even with significant industries in the region, industrial OA was estimated to contribute only ~ 5% of the total OA mass. Both source apportionment techniques suggest that oxygenated OA (OOA) constitutes the major fraction, contributing ~ 80% of OA mass. A novel approach combining AMS/PMF2 data with 14C measurements was applied to identify and quantify the fossil and non-fossil precursors of this fraction and to explicitly assess the related uncertainties. Results show with high statistical confidence that, despite extensive urban and industrial emissions, OOA is overwhelmingly non-fossil, formed via the oxidation of biogenic precursors, including monoterpenes. AMS/PMF2 results strongly suggest that the variability observed in the OOA chemical composition is mainly driven in our case by the aerosol photochemical age. This paper presents the impact of photochemistry on the increase of OOA oxygenation levels, formation of humic-like substances (HULIS) and the evolution of ?-pinene SOA (secondary OA) components.

El Haddad, I.; D'Anna, B.; Temime-Roussel, B.; Nicolas, M.; Boreave, A.; Favez, O.; Voisin, D.; Sciare, J.; George, C.; Jaffrezo, J.-L.; Wortham, H.; Marchand, N.

2013-08-01

344

An Electron Diffraction and Crystal Chemical Investigation of Oxygen/Fluorine Ordering in Niobium Oxyfluoride, NbO2F  

NASA Astrophysics Data System (ADS)

A careful electron diffraction study of the ReO3-type oxyfluoride NbO2F has revealed the presence of characteristic transverse polarized planes of diffuse intensity running through the G+/-* regions of reciprocal space as well as continuous rods of diffuse intensity running through the G+/-<1/21/2?>* regions of reciprocal space. The continuous planes of diffuse intensity in reciprocal space (perpendicular to each of the major crystal directions a, b and c) imply the existence of one-dimensional, oxygen/fluorine-ordered columns of atoms along <001> in real space but with no lateral correlation in the ordering from such <001> column to the next. The continuous lines of diffuse intensity along the <1/21/2?>* directions of reciprocal space are ascribed to Rigid Unit Mode (RUM) rotations of the constituent MX6 octahedral framework. A combination of bond-valence arguments and simple structure factor calculations are used to support this argument.

Brink, Frank J.; Withers, Ray L.; Norén, Lasse

2002-06-01

345

Technical Note: Performance of Chemical Ionization Reaction Time-of-Flight Mass Spectrometry (CIR-TOF-MS) for the measurement of atmospherically significant oxygenated volatile organic compounds  

NASA Astrophysics Data System (ADS)

The performance of a new chemical ionization reaction time-of-flight mass spectrometer (CIR-TOF-MS) utilising the environment chamber SAPHIR (Simulation of Atmospheric Photochemistry In a large Reaction Chamber- Forschungzentrum Jülich, Germany) is described. The work took place as part of the ACCENT (Atmospheric Composition and Change the European NeTwork for excellence) supported oxygenated volatile organic compound (OVOC) measurement intercomparison during January 2005. The experiment entailed the measurement of 14 different atmospherically significant OVOCs at various mixing ratios in the approximate range 10.0-0.6 ppbV. The CIR-TOF-MS operated throughout the exercise with the hydronium ion (H3O+) as the primary chemical ionization (CI) reagent in order to facilitate proton transfer to the analyte OVOCs. The results presented show that the CIR time-of-flight mass spectrometer is capable of detecting a wide range of atmospheric OVOCs at mixing ratios of around 10 ppbV in "real-time" (i.e. detection on the one-minute time scale), with sub-ppbV measurement also achieved following an increase in averaging time to tens of minutes. It is shown that in general OVOC measurement is made with high accuracy and precision, with integration time, mixing ratio and compound dependent values as good as 4-13% and 3-15% respectively. It is demonstrated that CIR-TOF-MS has rapid multi-channel response at the required sensitivity, accuracy and precision for atmospheric OVOC measurement.

Wyche, K. P.; Blake, R. S.; Ellis, A. M.; Monks, P. S.; Brauers, T.; Koppmann, R.; Apel, E. C.

2007-02-01

346

Performance of Chemical Ionization Reaction Time-of-Flight Mass Spectrometry (CIR-TOF-MS) for the measurement of atmospherically significant oxygenated volatile organic compounds  

NASA Astrophysics Data System (ADS)

The performance of a new chemical ionization reaction time-of-flight mass spectrometer (CIR-TOF-MS) utilising the environment chamber SAPHIR (Simulation of Atmospheric Photochemistry In a large Reaction Chamber - Forschungzentrum Jülich, Germany) is described. The work took place as part of the ACCENT (Atmospheric Composition and Change the European NeTwork for excellence) supported oxygenated volatile organic compound (OVOC) measurement intercomparison during January 2005. The experiment entailed the measurement of 14 different atmospherically significant OVOCs at various mixing ratios in the approximate range 10.0-0.6 ppbV. The CIR-TOF-MS operated throughout the exercise with the hydronium ion (H3O+) as the primary chemical ionization (CI) reagent in order to facilitate proton transfer to the analyte OVOCs. The results show the CIR time-of-flight mass spectrometer is capable of detecting a wide range of atmospheric OVOCs down to sub-ppbV mixing ratios with high accuracy and precision. It is demonstrated that the technique has rapid multi-channel response at the required sensitivity, accuracy and precision for atmospheric OVOC measurements.

Wyche, K. P.; Blake, R. S.; Ellis, A. M.; Monks, P. S.; Brauers, T.; Koppmann, R.; Apel, E.

2006-10-01

347

On the mechanism of the chemical and enzymic oxygenations of alpha-oxyprotohemin IX to Fe.biliverdin IX alpha.  

PubMed

alpha-Oxyprotohemin IX, an early intermediate in heme catabolism, was synthesized and its autoxidation to biliverdin IX alpha was studied. In anaerobic aqueous pyridine, alpha-oxyprotohemin (hexacoordinated) underwent autoreduction to yield an Fe(II) alpha-oxyprotoporphyrin pi-neutral radical bis(pyridine) complex, which reacted with an equimolar amount of dioxygen to give pyridine.verdohemochrome IX alpha and CO in 75-80% yield via an intermediate with an absorption maximum at 893 nm. Verdohemochrome IX alpha did not react with further dioxygen. Reconstituted apomyoglobin.alpha-oxyprotohemin IX complex (pentacoordinated) reacted with an equimolar amount of dioxygen to form an Fe(II) oxyporphyrin pi-neutral radical intermediate, which rearranged to a green compound (lambda max 660 and 704 nm) with elision of CO. The green product, which is probably an apomyoglobin.verdoheme pi-radical complex, reacted with another equimolar amount of dioxygen to give Fe(III).biliverdin IX alpha. Demetallation of this gave biliverdin IX alpha in overall yield of 70-75%. These results indicate that the sequence of oxyheme autoxidation in the presence of apomyoglobin is alpha-oxyprotoheme IX O2----CO----verdohemochrome IX alpha pi-radical O2----Fe(III).biliverdin IX alpha. A similar mechanism may prevail in vivo. The hexa- and pentacoordinated Fe(II) pi-radical form of the oxyporphyrin is crucial in triggering the autoxidation of the complex to verdohemochrome IX alpha. Further oxygenation of verdohemochrome IX alpha to Fe(III).biliverdin IX alpha occurred only in the pentacoordinated apomyoglobin.verdoheme Fe(II) complex. PMID:3456152

Sano, S; Sano, T; Morishima, I; Shiro, Y; Maeda, Y

1986-02-01

348

Electrocoagulation of chemical mechanical polishing (CMP) wastewater from semiconductor fabrication  

Microsoft Academic Search

Treatment of chemical mechanical polishing (CMP) wastewater is investigated. The CMP wastewater, as obtained from a large semiconductor manufacturer, was characterized by high suspended solids (SS) content, high Nephelometric turbidity unit (NTU), chemical oxygen demand (COD) concentration up to 500mg\\/l, copper concentration over 100mg\\/l and a milky color. This study was to explore the feasibility of treating the CMP wastewater

Chen L Lai; Sheng H Lin

2003-01-01

349

Fish processing wastewater treatment by combined biological and chemical processes aiming at water reuse  

Microsoft Academic Search

The objective of this work was to evaluate the potentiality of the reuse of fish processing wastewater by association between biological and chemical treatment. Heterotrophic microalgae systems were used in the biological treatment and coagulation–flocculation–sedimentation in the chemical step. Ammonia, chemical oxygen demand, total solids, suspended solids, turbidity, phosphorous, alkalinity, hardness, silica, sulfate, aluminium, calcium, magnesium, manganese, ferric and pH

Adriana Gonçalves da Silva Manetti; Marcio Oliveira Hornes; Marina Leite Mitterer; Maria Isabel Queiroz

2011-01-01

350

Chemical compositions of stars in the light of non-LTE spectral line formation: the evolution of carbon and oxygen in the Galaxy  

NASA Astrophysics Data System (ADS)

Non-LTE effects affect the formation of many spectral features in the spectra of late-type stars. This thesis investigates the effect on carbon and oxygen abundances. The non-LTE calculations have been performed with the code MULTI, using MARCS atmospheric models with 4500chemical evolution. The results are applied to high-quality observation for a sample of 43 turnoff halo stars with -3.24<[Fe/H]<-1.10. At low-metallicity, in particular due to decreasing Si background opacity, the non-LTE corrections affecting the 777 nm oxygen triplet are found to be more significant than those affecting the C I lines. The presence of a [C/O] upturn at low [Fe/H], here for the first time based on a solid non-LTE analysis, is confirmed, pointing to significant C yields from early generations of stars. This could be tracing the products of so-far elusive earlier Population III stars, or may signal rotationally-aided nucleosynthesis in more normal Population II stars.

Fabbian, D.

2008-01-01

351

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

Microsoft Academic Search

Oxygen isotope exchange between minerals and water in systems far from chemical equilibrium is controlled largely by surface reactions such as dissolution-precipitation. In many cases, this behavior can be modeled adequately by a simple pseudo-first order rate model that accounts for changes in surface area of the solid. Previous modeling of high temperature isotope exchange data for carbonates, sulfates, and

David R. Cole

2000-01-01

352

Living Without Oxygen: Oxygen Tolerance in Bacteria  

NSDL National Science Digital Library

This activity focuses on chemical processes, such as nitrogen fixation and denitrification, which are carried out by bacteria. Often the efficacy of these processes is determined by the amount of oxygen present in the environment in which the bacteria live. Much of the time, these processes are carried out by facultatively anaerobic bacteria in the suboxic region of lakes, oceans, sediments, and leaf litter. Students will discover whether facultatively anaerobic photoautotrophs share the same tolerance for oxygen, how differences in oxygen tolerance can be tested, and of what significance the tolerance for oxygen is in the nitrogen cycle. They will practice aseptic technique, monitor the growth of bacterial cultures, display their results graphically, and propose environmental problems associated with the oxygen tolerance of nitrogen fixers and denitifiers.

Harris, Sharon

353

Hypoxia-Inducible Factor Prolyl Hydroxylases are Oxygen Sensors in the Brain.  

National Technical Information Service (NTIS)

In mammalian cells, molecular oxygen is a requirement for normal growth, metabolism, and survival. Tissues in which oxygen demand surpasses oxygen supply become hypoxic and cannot maintain normal function. Thus, the ability to sense oxygen levels is neces...

C. Dalgard

2005-01-01

354

Hydrogen-oxygen flame acceleration and transition to detonation in channels with no-slip walls for a detailed chemical reaction model.  

PubMed

The features of flame acceleration in channels with wall friction and the deflagration to detonation transition (DDT) are investigated theoretically and using high resolution numerical simulations of two-dimensional reactive Navier-Stokes equations, including the effects of viscosity, thermal conduction, molecular diffusion, and a detailed chemical reaction mechanism for hydrogen-oxygen gaseous mixture. It is shown that in a wide channel, from the beginning, the flame velocity increases exponentially for a short time and then flame acceleration decreases, ending up with the abrupt increase of the combustion wave velocity and the actual transition to detonation. In a thin channel with a width smaller than the critical value, the exponential increase of the flame velocity is not bounded and ends up with the transition to detonation. The transition to detonation occurs due to the pressure pulse, which is formed at the tip of the accelerating flame. The amplitude of the pressure pulse grows exponentially due to a positive feedback coupling between the pressure pulse and the heat released in the reaction. Finally, large amplitude pressure pulse steepens into a strong shock coupled with the reaction zone forming the overdriven detonation. The evolution from a temperature gradient to a detonation via the Zeldovich gradient mechanism and its applicability to the deflagration-to-detonation transition is investigated for combustible materials whose chemistry is governed by chain-branching kinetics. The results of the high resolution simulations are fully consistent with experimental observations of the flame acceleration and DDT. PMID:21728653

Ivanov, M F; Kiverin, A D; Liberman, M A

2011-05-13

355

Chemical kinetics modelling of a decaying SF6 arc plasma in the presence of a solid organic insulator, copper, oxygen and water  

NASA Astrophysics Data System (ADS)

The composition variations occurring in decaying SF6 arc plasmas in the presence of atoms released from the vaporization of organic insulators (e.g. Teflon, polyethylene, polypropylene, megelit, nylon), copper, oxygen and water were studied between 12 000 K and 300 K by means of a chemical kinetics model. From the results obtained at 300 K and a pressure of 101.3 kPa: (i) the role of the impurities on the formation of the SF6 decomposition products: SF4 , SOF2 , SO2 F2 and S2 F10 , was determined; (ii) it was confirmed that the vaporization of an organic insulator leads to the appearance of CF4 and an increase in the generation of the major byproduct (SF4 +SOF2 ) which is correlated to the production of CF4 ; (iii) it was seen that, for a given amount of vaporized insulator, insulators that contain fluorine atoms brought about less SF6 decomposition than those that did not.

Coll, I.; Casanovas, A. M.; Vial, L.; Gleizes, A.; Casanovas, J.

2000-02-01

356

Rhizosphere anode model explains high oxygen levels during operation of a Glyceria maxima PMFC.  

PubMed

In this paper, the effect of root oxygen loss on energy recovery of the plant microbial fuel cell (PMFC) is described. In this manner, advanced understanding of competing processes within the rhizosphere-anode interface was provided. A microscopic model was developed on the basis of exudation, oxygen loss, biological oxidation, and biological current generation. The model was successfully validated by comparison to oxygen concentration profiles, volatile fatty acid profiles, and chemical oxygen demand profiles measured in the anode compartment. The model predicted oxic zones around roots in the anode of the plant microbial fuel cell. Results show no direct link between current generation and photosynthesis. This was consistent with the model which predicted that current was generated via hydrolysis of root-derived organic compounds. This result means that to optimize energy recovery of a PMFC, the plant selection should focus on high root biomass production combined with low oxygen loss. PMID:22265596

Timmers, Ruud A; Strik, David P B T B; Arampatzoglou, Cristina; Buisman, Cees J N; Hamelers, Hubertus V M

2011-11-11

357

Chemical and physical characteristics of water in estuaries of Texas, October 1976-September 1978  

USGS Publications Warehouse

This report presents basic data on the chemical and physical characteristics of water in the estuaries of Texas for the period October 1976-September 1978. The properties or constituents that are measured in the field are dissolved oxygen (DO), specific conductance, temperature, pH, and transparency by Secchi disk. Analyses conducted in the laboratory include the principal inorganic ions, biochemical oxygen demand (BOD), total organic carbon (TOC), ammonium, nitrite, nitrate, and total phosphate. (USGS)

Fisher, J. C.

1982-01-01

358

Inexpensive Travel Demand Techniques.  

National Technical Information Service (NTIS)

The report examines the applicability of simplified travel demand models suitable for small urban areas. The scope of the research is limited to simplified travel demand forecasting techniques that make use of routinely collected traffic ground counts. A ...

C. J. Khisty M. Y. Rahi

1987-01-01

359

Analytic study of the chain dark decomposition reaction of iodides - atomic iodine donors - in the active medium of a pulsed chemical oxygen-iodine laser: 2. Limiting parameters of the branching chain dark decomposition reaction of iodides  

SciTech Connect

The final stages in the development of a branching chain decomposition reaction of iodide in the active medium of a pulsed chemical oxygen-iodine laser (COIL) are analysed. Approximate expressions are derived to calculate the limiting parameters of the chain reaction: the final degree of iodide decomposition, the maximum concentration of excited iodine atoms, the time of its achievement, and concentrations of singlet oxygen and iodide at that moment. The limiting parameters, calculated by using these expressions for a typical composition of the active medium of a pulsed COIL, well coincide with the results of numerical calculations. (active media)

Andreeva, Tamara L; Kuznetsova, S V; Maslov, Aleksandr I; Sorokin, Vadim N [P N Lebedev Physical Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2009-08-31

360

Characterization study and five-cycle tests in a fixed-bed reactor of titania-supported nickel oxide as oxygen carriers for the chemical-looping combustion of methane.  

PubMed

Recent investigations have shown that in the combustion of carbonaceous compounds CO2 and NOx emissions to the atmosphere can be substantially reduced by using a two stage chemical-looping process. In this process, the reduction stage is undertaken in a first reactor in which the framework oxygen of a reducible inorganic oxide is used, instead of the usual atmospheric oxygen, for the combustion of a carbonaceous compound, for instance, methane. The outlet gas from this reactor is mostly composed of CO2 and steam as reaction products and further separation of these two components can be carried out easily by simple condensation of steam. Then, the oxygen carrier found in a reduced state is transported to a second reactor in which carrier regeneration with air takes place at relatively low temperatures, consequently preventing the formation of thermal NOx. Afterward, the regenerated carrier is carried to the first reactor to reinitiate a new cycle and so on for a number of repetitive cycles, while the carrier is able to withstand the severe chemical and thermal stresses involved in every cycle. In this paper, the performance of titania-supported nickel oxides has been investigated in a fixed-bed reactor as oxygen carriers for chemical-looping combustion of methane. Samples with different nickel oxide contents were prepared by successive incipient wet impregnations, and their performance as oxygen carriers was investigated at 900 degrees C and atmospheric pressure in five-cycle fixed-bed reactor tests using pure methane and pure air for the respective reduction and regeneration stages. The evolution of the outlet gas composition in each stage was followed by gas chromatography, and the involved chemical, structural, and textural changes of the carrier in the reactor bed were studied by using different characterization techniques. From the study, it is deduced that the reactivity of these nickel-based oxygen carriers is in the two involved stages and almost independent of the nickel loading. However, in the reduction stage, carbon deposition, from the thermal decomposition of methane, and CO emissions, mainly derived from the partial reduction of titania as support acting as an additional oxygen source, may impose some constraints to the efficiency of the overall chemical-looping combustion process in CO2 capture. PMID:16124317

Corbella, Beatriz M; de Diego, Luis F; García-Labiano, Francisco; Adánez, Juan; Palaciost, José M

2005-08-01

361

Mineralogy, petrography and bulk chemical, iodine-xenon, and oxygen-isotopic compositions of dark inclusions in the reduced CV3 chondrite Efremovka  

NASA Astrophysics Data System (ADS)

We studied the petrography, mineralogy and bulk chemical, I-Xe, and oxygen isotopic compositions of three dark inclusions (E39, E53, and E80) in the reduced CV3 chondrite Efremovka. They consist of chondrules, Ca-Al-rich inclusions (CAIs) and fine-grained matrix. Primary minerals in chondrules and CAIs are pseudomorphed to various degrees by a mixture largely composed of abundant (>95%), fine-grained (<0.2 microns) fayalitic olivine (Fa35-42) and minor amounts of chlorite, poorly-crystalline Si-Al-rich material, and chromite; chondrule and CAI shapes and textures are well-preserved. Secondary Ca-rich minerals (Ti-andradite, kirschsteinite, Fe-diopside) are common in chondrule pseudomorphs and matrices in E39 and E80. The degree of replacement increases from E53 to E39 to E80. Fayalitic olivines are heavily-strained and contain abundant voids, similar to those in incompletely dehydrated phyllosilicates in metamorphosed CM and CI chondrites. Opaque nodules in chondrules consist of Ni- and Co-rich taenite, Co-rich kamacite, and wairauite; sulfides are rare; magnetite is absent. Bulk oxygen isotopic compositions of E39 and E53 plot in the field of aqueously altered CM chondrites, close to the terrestrial fractionation line; the more heavily altered E39 is isotopically heavier than the less altered E53. The apparent I-Xe age of E53 is 5.4 Ma earlier than Bjurbule and 5.7 +/- 2.0 Ma earlier than E39. The I-Xe data are consistent with the most heavily altered dark inclusion E39 having experienced either longer or later alteration than E53. Bulk lithophile elements in E39 and E53 most closely match those of CO chondrites, except that Ca is depleted and K and As are enriched. Both inclusions are depleted in Se by factors of 3-5 compared to mean CO, CV, CR or CK chondrites. Zinc in E39 is lower than the mean of any carbonaceous chondrite groups, but in E53 Zn is similar to the means in CO, CV, and CK chondrites. The Efremovka dark inclusions experienced various degrees of aqueous alteration, followed by low degree thermal metamorphism in an asteroidal environment. These processes resulted in preferential oxidation of iron from opaque nodules and formation of Ni- and Co-rich metal, metasomatic alteration of primary minerals in chondrules and CAIs, and formation of fayalitic olivine and secondary Ca-Fe-rich minerals. Based on the observed similarities of the alteration mineralization in the Efremovka and Allende dark inclusions, we infer that the latter may have experienced similar alteration processes.

Krot, A. N.; Brearley, A. J.; Ulyanov, A. A.; Biryukov, V. V.; Swindle, T. D.; Keil, K.; Mittlefehldt, D. W.; Scott, E. R. D.; Clayton, R. N.; Mayeda, T. K.

1999-01-01

362

Ridesharing: Transportation demand management  

Microsoft Academic Search

The 13 papers in the report deal with the following areas: Comparison of transportation demand management market research study results and transportation management association development in three suburban activity centers; Ten cities' strategies for transportation demand management; Key considerations for developing local government transportation system management programs; First Hill Action Plan: A unique public\\/private approach to transportation demand management; Comparison

R. Valdez; J. Wang; C. P. Flynn; L. J. Glazer; S. Pultz

1989-01-01

363

Demand for Sport  

Microsoft Academic Search

This article reviews international literature on the demand for professional sport. The first part presents a conceptual framework for understanding the sources and determinants of the demand for professional sporting contests. The second part reviews empirical evidence on key determinants of attendance at sporting events, and on other sources of demand, such as broadcasting, sponsorship, and merchandising. The review concludes

Jeffery Borland

2003-01-01

364

Electricity demand curtailment planning  

SciTech Connect

The state of electricity demand curtailment planning for long term electricity supply disruptions is reviewed. Legal, institutional and technological problems associated with demand curtailment plans are examined, and the existence of well defined social objectives on the part of planners is questioned. A linear programming approach to electricity demand curtailment planning is presented.

Allentuck, J; Carroll, O; Schnader, M

1980-01-01

365

Oxygen, hypoxia, and stress.  

PubMed

Since cyanobacteria began to photosynthesize and introduce the colorless and odorless gas oxygen into the earth's atmosphere some 2.5 billion years ago, human evolution has been intrinsically linked to this critical molecule. Initially, the electrophilic chemical properties of oxygen rendered it a formidable toxic challenge to organisms; however, eukaryotic cells, following the incorporation of bacterial-derived mitochondria, evolved to make beneficial use of the chemical properties of molecular oxygen as the final electron acceptor in the highly efficient production of cellular energy supplies in the form of adenosine triphosphate. Because of both its necessity for eukaryotic life and its reactive chemical nature, however, a delicate balance exists between the supply of oxygen to a cell/tissue/organism and the beneficial or harmful outcome. In this minireview, we shall discuss the role of oxygen in metabolism with a particular emphasis on outcomes when oxygen supply is significantly altered. Furthermore, we will describe endogenous mechanisms that have evolved to protect cells and tissues during such adverse conditions and may prove useful as novel therapeutic targets in a range of disease states where oxygen-related stress occurs. PMID:17483207

Taylor, Cormac T; Pouyssegur, Jacques

2007-05-04

366

Reverse Pressure Effect on Suit Demand Regulator.  

National Technical Information Service (NTIS)

A Gemini B Suit Oxygen Demand and Relief Regulator Valve, P/N 52-83700-1171, was exposed to a simulated cabin pressure of 0.1 psia for 33 days. The gas supply to the regulator was closed during the 33 day exposure, permitting the simulated suit circuit pr...

1968-01-01

367

On demand, non-halon, fire extinguishing systems  

NASA Astrophysics Data System (ADS)

A system and process for on-demand generation of inert, non-flammable gases and water vapor to decrease the available atmospheric oxygen in the ullage of a hydrocarbon fuel storage tank to a level that will not support combustion of the hydrocarbon fuel, is disclosed. One, or more, of a variety of non-Halon, fire suppressor charges are selectively contained in one or more gas generating cartridges. The gas generating cartridge(s), when activated, cause release of these charges to prOmote rapid chemical reactions and supply inert, non-flammable gases and water vapor to the tank ullage. Activation is accomplished in aircraft by either pilot action or by pressure and temperature sensors contained within the hydrocarbon fuel tank.

Smith, Benjamin D.

1995-06-01

368

On demand, non-halon, fire extinguishing systems  

NASA Astrophysics Data System (ADS)

A system and process for on-demand generation of inert, nonflammable gases and water vapor to decrease the available atmospheric oxygen in the ullage of a hydrocarbon fuel storage tank to a level that will not support combustion of the hydrocarbon fuel, is disclosed. One, or more, of a variety of non-Halon, fire suppressor charges are selectively contained in one or more gas generating cartridges. The gas generating cartridge(s), when activated, cause release of these charges to promote rapid chemical reactions and supply inert, nonflammable gases and water vapor to the tank ullage. Activation is accomplished in aircraft by, either pilot action or, by pressure and temperature sensors contained within the hydrocarbon fuel tank.

Smith, Bengamin D.

1993-06-01

369

Determination of biodegradability of phenolic compounds, characteristic to wastewater of the oil-shale chemical industry, on activated sludge by oxygen uptake measurement.  

PubMed

The aim of this study was to investigate the biodegradation of phenol, o-cresol and p-cresol individually and as bi-substrate mixtures at low initial substrate concentrations. Activated sludge was taken from the Kohtla-Järve wastewater treatment plant, Estonia, which is also treating phenolic wastewater from the oil-shale chemical industry and is considered to be acclimated to the phenolic compounds. Respirometric data have been used for evaluation of the kinetic parameters describing the bio-oxidation of substrates. Activated sludge was able to degrade phenol and p-cresol faster than o-cresol, showing better affinity to p-cresol. However, at higher concentrations, phenol and p-cresol exhibited also an inhibitory effect to the microorganisms. The highest values for maximum rate of oxygen uptake (V(O2,max)) were obtained for the bi-substrate system of phenol--p-cresol among the mixtures containing both substrates at equal concentrations from 0.005 mM to 0.050 mM. Concerning the systems containing one substrate at 0.1 mM and the other substrate varied in the abovementioned range, the highest V(O2,max) values were found for phenol--o-cresol(0.1 mM). The interaction parameters indicated that phenol had a stronger inhibition effect on the biodegradation of p-cresol than p-cresol had on the biodegradation of phenol. However, the obtained interaction parameters for systems of phenol--o-cresol indicated that o-cresol had a stronger inhibition effect on the biodegradation of phenol, which in turn had a mild inhibition or even enhancing effect on the biodegradation of o-cresol. In the case of a 1:1 mixture, phenol and o-cresol had a similar mild inhibition effect on each other's biodegradation. PMID:22519119

Lepik, Riina; Tenno, Toomas

370

Characterization of singlet oxygen production and its involvement in photodamage of Photosystem II in the cyanobacterium Synechocystis PCC 6803 by histidine-mediated chemical trapping.  

PubMed

Singlet oxygen production in intact cells of the cynobacterium Synechocystis 6803 was studied using chemical trapping by histidine, which leads to O2 uptake during illumination. The rate of O2 uptake, measured by a standard Clark-type electrode, is enhanced in the presence of D2O, which increases the lifetime of (1)O2, and suppressed by the (1)O2 quencher NaN3. Due to the limited mobility of (1)O2 these data demonstrate that exogenous histidine reaches close vicinity of (1)O2 production sites inside the cells. Flash induced chlorophyll fluorescence measurements showed that histidine does not inhibit Photosystem II activity up to 5mM concentration. By applying the histidine-mediated O2 uptake method we showed that (1)O2 production linearly increases with light intensity even above the saturation of photosynthesis. We also studied (1)O2 production in site directed mutants in which the Gln residue at the 130th position of the D1 reaction center subunit was changed to either Glu or Leu, which affect the efficiency of nonradiative charge recombination from the primary radical pair (Rappaport et al. 2002, Biochemistry 41: 8518-8527; Cser and Vass 2007, BBA 1767:233-243). We found that the D1-Gln130Glu mutant showed decreased (1)O2 production concomitant with decreased rate of photodamage relative to the WT, whereas both (1)O2 production and photodamage were enhanced in the D1-Gln130Leu mutant. The data are discussed in the framework of the model of photoinhibition in which (3)P680 mediated (1)O2 production plays a key role in PSII photodamage, and nonradiative charge recombination of the primary charge separated state provides a photoprotective pathway. PMID:23466334

Rehman, Ateeq Ur; Cser, Krisztián; Sass, László; Vass, Imre

2013-03-04

371

Oxygen-Nitrogen Relationships in Autotrophic Nitrification  

PubMed Central

Oxygen utilization by the autotrophic nitrifiers Nitrosomonas and Nitrobacter was studied. Experimental evidence is presented which reflects the effect of carbon dioxide fixation on overall oxygen utilization in autotrophic nitrification. Measurement of dissolved oxygen and inorganic nitrogen changes indicates that oxygen-nitrogen ratios in inorganic nitrogen oxidation are equal to 3.22 parts (expressed in milligrams per liter) of oxygen per part of ammonia nitrogen oxidized to nitrite nitrogen and 1.11 parts of oxygen per part of nitrite nitrogen oxidized to nitrate nitrogen. These values rather than the stoichiometric ratios should be used in nitrogenous oxygen demand calculations.

Wezernak, C. T.; Gannon, J. J.

1967-01-01

372

Ethanol Demand in United States Gasoline Production  

SciTech Connect

The Oak Ridge National Laboratory (OWL) Refinery Yield Model (RYM) has been used to estimate the demand for ethanol in U.S. gasoline production in year 2010. Study cases examine ethanol demand with variations in world oil price, cost of competing oxygenate, ethanol value, and gasoline specifications. For combined-regions outside California summer ethanol demand is dominated by conventional gasoline (CG) because the premised share of reformulated gasoline (RFG) production is relatively low and because CG offers greater flexibility for blending high vapor pressure components like ethanol. Vapor pressure advantages disappear for winter CG, but total ethanol used in winter RFG remains low because of the low RFG production share. In California, relatively less ethanol is used in CG because the RFG production share is very high. During the winter in California, there is a significant increase in use of ethanol in RFG, as ethanol displaces lower-vapor-pressure ethers. Estimated U.S. ethanol demand is a function of the refiner value of ethanol. For example, ethanol demand for reference conditions in year 2010 is 2 billion gallons per year (BGY) at a refiner value of $1.00 per gallon (1996 dollars), and 9 BGY at a refiner value of $0.60 per gallon. Ethanol demand could be increased with higher oil prices, or by changes in gasoline specifications for oxygen content, sulfur content, emissions of volatile organic compounds (VOCS), and octane numbers.

Hadder, G.R.

1998-11-24

373

Simultaneous analysis of oxygenated and nitrated polycyclic aromatic hydrocarbons on standard reference material 1649a (urban dust) and on natural ambient air samples by gas chromatography–mass spectrometry with negative ion chemical ionisation  

Microsoft Academic Search

This study deals with the development of a routine analytical method using gas chromatography–mass spectrometry with negative ion chemical ionisation (GC\\/NICI-MS) for the determination of 17 nitrated polycyclic aromatic hydrocarbons (NPAHs) and 9 oxygenated polycyclic aromatic hydrocarbons (OPAHs) present at low concentrations in the atmosphere. This method includes a liquid chromatography purification procedure on solid-phase extraction (SPE) cartridge. Application of

A. Albinet; E. Leoz-Garziandia; H. Budzinski; E. ViIlenave

2006-01-01

374

Simultaneous determination by ultra-performance liquid chromatography–atmospheric pressure chemical ionization time-of-flight mass spectrometry of nitrated and oxygenated PAHs found in air and soot particles  

Microsoft Academic Search

An ultra-performance liquid chromatographic-atmospheric pressure chemical ionization time-of-flight mass spectrometric (UPLC-APCIToFMS)\\u000a method for rapid analysis of twelve nitrated polycyclic aromatic hydrocarbons (NPAHs) and nine oxygenated polycyclic aromatic\\u000a hydrocarbons (OPAHs) in particle samples has been developed. The extraction step using pressurized liquid extraction was optimized\\u000a by experimental design methods and the concentrated extracts were analyzed without further clean-up. Matrix effects resulting

Giovanni Mirivel; Véronique Riffault; Jean-Claude Galloo

2010-01-01

375

Sensory and chemical changes of young white wines stored under oxygen. An assessment of the role played by aldehydes and some other important odorants  

Microsoft Academic Search

The aroma of young white wines altered by oxygen was described by a sensory panel which defined the terms: cooked vegetables, liquor, woody, cider and pungent. Twenty-seven young white wines stored under oxygen for 1 week were analyzed by the sensory panel and were further analyzed by gas chromatography (GC)-Ion trap mass spectrometry (MS) to determine their contents in hexanal,

A Escudero; E Asensio; J Cacho; V Ferreira

2002-01-01

376

Evaluated Chemical Kinetic Data for the Reactions of Atomic Oxygen O(3P) with Saturated Organic Compounds in the Gas Phase  

Microsoft Academic Search

Rate constants and mechanisms for the gas phase reactions of atomic oxygen O(3P) with organic compounds having only saturated C–C bonds are compiled and critically evaluated. Data are given for the alkanes, cycloalkanes, haloalkanes, oxygen and nitrogen containing organic compounds, and free radicals. In addition, data are given for some miscellaneous compounds containing boron, silicon, germane, and mercury. From a

John T. Herron

1988-01-01

377

The industrial hydrogen and oxygen market in the Pacific Northwest  

SciTech Connect

The Federal Columbia River Power System is projected to have surplus hydroelectricity available during peak seasons for the next twenty years. Blocks of power averaging 2500 MW(e) in peak months at rates below 20 mills/kWh may be available. Under these conditions, electrolytic hydrogen becomes attractive if suitable markets exist. Objective of the analysis was to determine the market potential of large (>1 MW(e), advanced technology electrolyzers for industrial applications in the BPA service area. Industrial hydrogen and oxygen applications were identified based, in part, on current needs for hydrogen and the industry's regional energy demand. Hydrogen demand in these industries was assessed for both fuel and chemical needs. A questionnaire was sent to over 200 Pacific Northwest industrial sites. The report also discusses the regional environmental and regulatory issues and their potential impact on hydrogen and competing fuels. Cost factors which can affect the potential market for electrolytic hydrogen and oxygen were analyzed as well. One of the most important factors identified, in addition to electricity costs, was the by-product credit for the co-produced oxygen. A sufficient demand exists to warrant a concerted effort to introduce electrolyzers to potential users.

Blazek, C.F.; Donakowski, T.D.; Novil, M.

1986-01-01

378

Electrocatalysis of anodic oxygen-transfer reactions: The electrochemical incineration of benzoquinone  

Microsoft Academic Search

The electrochemical performance of several anode materials is compared for the electrochemical incineration of p-benzoquinone in acetate buffer media (pH 5). The chemical oxygen demand (COD) estimated for benzoquinone by titration with standard permanganate solution can be decreased to virtually zero by electrolysis at electrodes comprised of Fe(III)-doped β-PbOâ films on Ti substrates. Carbon dioxide is a product of the

Jianren Feng; L. L. Houk; D. C. Johnson; S. N. Lowery; J. J. Carey

1995-01-01

379

Analysis of the atmospheric distribution, sources, and sinks of oxygenated volatile organic chemicals based on measurements over the Pacific during TRACE-P  

NASA Astrophysics Data System (ADS)

Airborne measurements of a large number of oxygenated volatile organic chemicals (OVOC) were carried out in the Pacific troposphere (0.1-12 km) in winter/spring of 2001 (24 February to 10 April). Specifically, these measurements included acetone (CH3COCH3), methylethyl ketone (CH3COC2H5, MEK), methanol (CH3OH), ethanol (C2H5OH), acetaldehyde (CH3CHO), propionaldehyde (C2H5CHO), peroxyacylnitrates (PANs) (CnH2n+1COO2NO2), and organic nitrates (CnH2n+1ONO2). Complementary measurements of formaldehyde (HCHO), methyl hydroperoxide (CH3OOH), and selected tracers were also available. OVOC were abundant in the clean troposphere and were greatly enhanced in the outflow regions from Asia. Background mixing ratios were typically highest in the lower troposphere and declined toward the upper troposphere and the lowermost stratosphere. Their total abundance (?OVOC) was nearly twice that of nonmethane hydrocarbons (?C2-C8 NMHC). Throughout the troposphere, the OH reactivity of OVOC is comparable to that of methane and far exceeds that of NMHC. A comparison of these data with western Pacific observations collected some 7 years earlier (February-March 1994) did not reveal significant differences. Mixing ratios of OVOC were strongly correlated with each other as well as with tracers of fossil and biomass/biofuel combustion. Analysis of the relative enhancement of selected OVOC with respect to CH3Cl and CO in 12 plumes originating from fires and sampled in the free troposphere (3-11 km) is used to assess their primary and secondary emissions from biomass combustion. The composition of these plumes also indicates a large shift of reactive nitrogen into the PAN reservoir thereby limiting ozone formation. A three-dimensional global model that uses state of the art chemistry and source information is used to compare measured and simulated mixing ratios of selected OVOC. While there is reasonable agreement in many cases, measured aldehyde concentrations are significantly larger than predicted. At their observed levels, acetaldehyde mixing ratios are shown to be an important source of HCHO (and HOx) and PAN in the troposphere. On the basis of presently known chemistry, measured mixing ratios of aldehydes and PANs are mutually incompatible. We provide rough estimates of the global sources of several OVOC and conclude that collectively these are extremely large (150-500 Tg C yr-1) but remain poorly quantified.

Singh, H. B.; Salas, L. J.; Chatfield, R. B.; Czech, E.; Fried, A.; Walega, J.; Evans, M. J.; Field, B. D.; Jacob, D. J.; Blake, D.; Heikes, B.; Talbot, R.; Sachse, G.; Crawford, J. H.; Avery, M. A.; Sandholm, S.; Fuelberg, H.

2004-08-01

380

Structure of the oxygen-evolving complex of photosystem II: information on the S(2) state through quantum chemical calculation of its magnetic properties.  

PubMed

Twelve structural models for the S(2) state of the oxygen-evolving complex (OEC) of photosystem II are evaluated in terms of their magnetic properties. The set includes ten models based on the 'fused twist' core topology derived by polarized EXAFS spectra and two related models proposed in recent mechanistic investigations. Optimized geometries and spin population analyses suggest that Mn(iii), which is most often identified with the manganese ion at site D, is always associated with a penta-coordinate environment, unless a chloride is directly ligated to the metal. Exchange coupling constants were determined by broken-symmetry density functional theory calculations and the complete spectrum of magnetic sublevels was obtained by direct diagonalization of the Heisenberg Hamiltonian. Seven models display a doublet ground state and are considered spectroscopic models for the ground state corresponding to the multiline signal (MLS) of the S(2) state of the OEC, whereas the remaining five models display a sextet ground state and could be related to the g = 4.1 signal of the S(2) state. It is found that the sign of the exchange coupling constant between the Mn centres at positions A and B of the cluster is directly related to the ground state multiplicity, implying that interconversion between the doublet and sextet can be induced by only small structural perturbations. The recently proposed quantum chemical method for the calculation of (55)Mn hyperfine coupling constants is subsequently applied to the S(2) MLS state models and the quantities that enter into the individual steps of the procedure (site-spin expectation values, intrinsic site isotropic hyperfine parameters and projected (55)Mn isotropic hyperfine constants) are analyzed and discussed in detail with respect to the structural and electronic features of each model. The current approach performs promisingly. It reacts sensitively to structural distortions and hence may be able to distinguish between different structural proposals. Thus it emerges as a useful contributor to the ongoing efforts that aim at establishing correlations between the body of spectroscopic data available for the various S(i) states of the OEC and their actual geometric features. PMID:19639153

Pantazis, Dimitrios A; Orio, Maylis; Petrenko, Taras; Zein, Samir; Lubitz, Wolfgang; Messinger, Johannes; Neese, Frank

2009-06-23

381

Demand Control Chart  

Microsoft Academic Search

The existing inventory managements bear a relation to forecasting or assumptions. So these methods become more complicated and more expensive systems as time goes. This paper developed a practical inventory system which is called DCC (demand control chart). DCC does not 'forecast' but 'control' the trend of demand without assumptions. According to the trend of sales, DCC adjusts an order

SiHyun Paik; SukChul Rim

2006-01-01

382

Supply and Demand  

NSDL National Science Digital Library

This lesson from Illuminations allows students to learn about linear equations in a real-world setting. The material applies linear equations to the concept of supply and demand. Students will be able to translate between table, graph and equation representations for supply and demand data. The lesson is intended for grades 9-12 and should require two class periods to complete.

2010-12-03

383

A Demanding Public.  

ERIC Educational Resources Information Center

This curriculum unit, intended for use with gifted students and others, uses the daily activities of a zoo gift shop to teach principles of economics including the law of demand, the nature of a market, and influences on product demand. (DB)

Coleman, Diane J.; Monger, Joyce R.

1992-01-01

384

Continuous Recording of Physico-Chemical Measurement of Quantities of Bacterial Cultures. I. Building of Apparatus for the Recording of Relative Turbidity, Redoxpotential and Dissolved Oxygen.  

National Technical Information Service (NTIS)

In this report an apparatus is described which in growing bacteria cultures makes possible continuous recording of the dissolved oxygen, redoxpotential and turbidity. The results of measurements obtained with the apparatus in 5 different varieties of bact...

G. Horn H. E. Jacob W. Bockel

1965-01-01

385

Controlling electric power demand  

SciTech Connect

Traditionally, demand control has not been viewed as an energy conservation measure, its intent being to reduce the demand peak to lower the electric bill demand charge by deferring the use of a block of power to another demand interval. Any energy savings were essentially incidental and unintentional, resulting from curtailment of loads that could not be assumed at another time. This article considers a microprocessor-based multiplexed system linked to a minicomputer to control electric power demand in a winery. In addition to delivering an annual return on investment of 55 percent in electric bill savings, the system provides a bonus in the form of alarm and monitoring capability for critical processes.

Eikenberry, J.

1984-11-15

386

The electric oxygen-iodine laser: Chemical kinetics of O2(a 1 ?) production and I(2P1\\/2) excitation in microwave discharge systems  

Microsoft Academic Search

Generation of singlet oxygen metastables, O2(a 1 ?), in an electric discharge plasma offers the potential for development of compact electric oxygen-iodine laser (EOIL) systems using a recyclable, all-gas-phase medium. The primary technical challenge for this concept is to develop a high-power, scalable electric discharge configuration that can produce high yields and flow rates of O2(a) to support I( 2

W. T. Rawlins; S. Lee; W. J. Kessler; D. B. Oakes; L. G. Piper; S. J. Davis

387

The electric oxygen-iodine laser: chemical kinetics of O2(a1Delta) production and I(2 P1\\/2) excitation in microwave discharge systems  

Microsoft Academic Search

Generation of singlet oxygen metastables, O2(a1Delta), in an electric discharge plasma offers the potential for development of compact electric oxygen-iodine laser (EOIL) systems using a recyclable, all-gas-phase medium. The primary technical challenge for this concept is to develop a high-power, scalable electric discharge configuration that can produce high yields and flow rates of O2(a) to support I(2P1\\/2->2P3\\/2) lasing at high

W. T. Rawlins; S. Lee; W. J. Kessler; D. B. Oakes; L. G. Piper; S. J. Davis

2006-01-01

388

Reduction and oxidation kinetics of Mn 3O 4\\/Mg–ZrO 2 oxygen carrier particles for chemical-looping combustion  

Microsoft Academic Search

The kinetics of reduction with methane and oxidation with oxygen of Mn3O4 supported on Mg–ZrO2 prepared by freeze granulation has been investigated. The reactivity experiments were performed in a thermogravimetric analyzer (TGA) using different reacting gas concentrations and temperatures in the range of 1073–1223K. The oxygen carrier particles showed high reactivity during both reduction and oxidation at all investigated temperatures.

Qamar Zafar; Alberto Abad; Tobias Mattisson; Börje Gevert; Michael Strand

2007-01-01

389

Evaluated Chemical Kinetic Data for the Reactions of Atomic Oxygen O(3P) with Saturated Organic Compounds in the Gas Phase  

Microsoft Academic Search

Rate constants and mechanisms for the gas phase reactions of atomic oxygen O(³P) with organic compounds having only saturated C--C bonds are compiled and critically evaluated. Data are given for the alkanes, cycloalkanes, haloalkanes, oxygen and nitrogen containing organic compounds, and free radicals. In addition, data are given for some miscellaneous compounds containing boron, silicon, germane, and mercury. From a

John T. Herron

1988-01-01

390

Destroying chemical wastes in commercial-scale incinerators. Final report  

Microsoft Academic Search

Tests were conducted at Zimpro, Inc., Rothschild, Wisconsin, to determine the effectiveness of wet air oxidation for destruction of two selected aqueous industrial wastes: coke plant waste and Amiben (herbicide) manufacturing waste. A pilot scale facility was tested for the coke plant waste with less than 6g\\/1 total solids and 5.5 g\\/1 Biological Oxygen Demand (BOD5), chemical compounds such as

J. W. Adams; N. J. Cunningham; J. C. Harris; P. L. Levins; J. L. Stauffer

1976-01-01

391

Algal density dependent bioconcentration factors of hydrophobic chemicals  

Microsoft Academic Search

The bioconcentration factors (BCFs) of anthracene, hexachlorobenzene, 4,4?-dichlorobiphenyl, and 2,2?5,5?-tetrachlorobiphenyl decreased with increasing density of the algae Chlorella vulgaris and Chlorella pyrenoidosa. Concomitant with algal density, the organic carbon concentration as measured by chemical oxygen demand (COD) in the aqueous phase after centrifugation of the algal suspensions, increased. It is argued that the decreased BCFs in the presence of algae

Dick T. H. M. Sijm; Joost Middelkoop; Keno Vrisekoop

1995-01-01

392

Chemical Analyses of Commercial Shell Egg Wash Water  

Microsoft Academic Search

SUMMARY Wash water was collected from the first (W1) and second (W2) egg washers in series in 3 different commercial facilities (plants X, Y, and Z) and evaluated for temperature, pH, chlorine, soluble iron (ferrous), total dissolved solids (TDS), total suspended solids (TSS), total Kjeldahl nitrogen (TKN), and chemical oxygen demand (COD). Temperature of W1 and W2 ranged from 39.7

J. K. Northcutt; M. T. Musgrove; D. R. Jones

2005-01-01

393

Oxygen Therapy  

MedlinePLUS

... not smoke near oxygen, or keep oxygen near open flames, or other sources of heat or flames Doctor’s Office Telephone: Your healthcare provider has prescribed oxygen therapy for your lung condition The ATS Patient Information Series is a public service ...

394

40 CFR 799.5087 - Chemical testing requirements for second group of high production volume chemicals (HPV2).  

Code of Federal Regulations, 2013 CFR

...Biodegradability of Organic CompoundsâMethod by Analysis of Biochemical Oxygen Demand (Closed Bottle Test). First Edition, October...Biodegradability of Organic CompoundsâDetermination of Biochemical Oxygen Demand in a Two-Phase Closed Bottle Test....

2013-07-01

395

40 CFR 799.5089 - Chemical testing requirements for third group of high production volume chemicals (HPV3).  

Code of Federal Regulations, 2013 CFR

...Biodegradability of Organic CompoundsâMethod by Analysis of Biochemical Oxygen Demand (Closed Bottle Test). First Edition, October...Biodegradability of Organic CompoundsâDetermination of Biochemical Oxygen Demand in a Two-Phase Closed Bottle Test....

2013-07-01

396

Oxygen Uptake Rates of Benthal Deposits on the Upper Passiac River.  

National Technical Information Service (NTIS)

An in situ benthal respirometer was utilized to determine benthal oxygen demands on the Passaic river near Little Falls, New Jersey. Different deposits on the stream were examined for exhibited demands. These demands were then examined from the viewpoint ...

O. M. Donovan J. V. Hunter

1969-01-01

397

Oxygen depletion in the New York apex: causes and consequences  

Microsoft Academic Search

Dissolved oxygen concentrations in water of the New York Bight apex are near saturation except in summer when a stable thermocline exists and concentrations in the lower layer can drop to 10% of saturation. Mass balances of oxygen and carbon cycles in the apex were examined. Photosynthetically produced carbon accounts for most of the oxygen demand, particularly in summer. Oxygen

D. A. Segar; G. A. Berberian

1976-01-01

398

Evaluation of oxygen utilization as an indicator of municipal solid-waste compost stability  

SciTech Connect

This research evaluated oxygen utilization parameters as indicators of MSW compost stability. Parameters evaluated were the oxygen utilization rate (OUR), specific oxygen uptake rate (SOUR), five-day biochemical oxygen demand, and chemical oxygen demand. In addition, other suggested indicators of stability were investigated including percent volatile solids, volatile solids reduction, nitrogen content, carbon: nitrogen ratio, and reheating potential (RP). OUR is a measure of the rate of oxygen utilization by the microorganisms in the decomposition of organic matter in compost. OUR was observed to be sensitive to the degree of stabilization and decreased with increasing compost age and stability. OUR values near zero indicate that the compost microorganisms are in a state of endogenous respiration, which is characteristic of a stable compost. Therefore, OUR is an excellent indicator of stability. A number of disadvantages are associated with OUR for practical application. Therefore, other parameters were evaluated as indicators of stability based on their statistical correlation to OUR. RP exhibited the strongest correlation to OUR. In combination, RP and SOUR were the two parameters which exhibited the strongest correlation to OUR. OUR, RP, and SOUR are all measures of microbial activity which reflect the degree of organic decomposition, and therefore, stability. Based on the results of this research; OUR, RP, and SOUR are useful parameters in assessing compost stability.

Zimmerman, R.A.

1991-01-01

399

Dissolved oxygen stratification in two micro-tidal partially-mixed estuaries  

Microsoft Academic Search

The controlling physical factors for vertical oxygen stratification in micro-tidal, partially-mixed estuaries are discussed in this paper. A theoretical deduction shows that vertical stratification of dissolved oxygen (DO) concentration can be explained by the extended Hansen and Rattray's Central Region theory, which suggests that in addition to biological factors such as photosynthesis, biochemical oxygen demand (BOD), sediment oxygen demand (SOD),

Jing Lin; Lian Xie; Len J. Pietrafesa; Jian Shen; Michael A. Mallin; Michael J. Durako

2006-01-01

400

Industrial Demand for Energy.  

National Technical Information Service (NTIS)

The characteristics of industrial demand for energy are examined. The report focuses on four topics: Interfuel substitution in two-digit industries; substitution among energy, capital and labor; technical change in energy use; and dynamic structure of ene...

R. Halvorsen

1977-01-01

401

Residential Sector Demand Module  

EIA Publications

Model Documentation - Documents the objectives, analytical approach, and development of the National Energy Modeling System (NEMS) Residential Sector Demand Module. The report catalogues and describes the model assumptions, computational methodology, parameter estimation techniques, and FORTRAN source code.

Owen Comstock

2012-12-19

402

Industrial Demand Module  

EIA Publications

Documents the objectives, analytical approach, and development of the National Energy Modeling System (NEMS) Industrial Demand Module. The report catalogues and describes model assumptions, computational methodology, parameter estimation techniques, and model source code.

Kelly Perl

2013-09-30

403

Cinema Demand In Germany  

Microsoft Academic Search

This paper examines the German cinema market using time series data covering the period 1950–2002. Applying estimation techniques such as OLS, 2SLS and SUR, we identify interrelations between the number of seats, the average real prices and the demand for movies per capita. Furthermore, we test for the long-run relationship between demand, prices and real income and estimate the elasticity

Ralf Dewenter; Michael Westermann

2005-01-01

404

Tissue oxygenation and routine nursing procedures in critically ill patients.  

PubMed

Maintaining adequate oxygenation to promote vital organ functions represents a common challenge for the critical care nurse. Critically ill patients with impaired cardiac function may be particularly vulnerable to tissue oxygen deprivation because they have limited ability to increase oxygen delivery when oxygen demands increase. Consequently, routine nursing procedures that increase oxygen requirements may have adverse effects on tissue oxygenation. Interventions that enhance patient tolerance to nursing procedures by supporting the balance between oxygen supply and demand promote physiologic adaptation and may prevent complications associated with hypoxia such as cardiac dysrhythmias, hypotension, and cardiac arrest. This discussion will focus on the principles of tissue oxygenation, the effects of nursing interventions on oxygen demand, and interventions that may enhance patient tolerance to routine nursing interventions. PMID:9200016

Jesurum, J

1997-07-01

405

A chemical diffusion-controlled electrode reaction at the compact La{sub 1{minus}x}Sr{sub x}MnO{sub 3}/stabilized zirconia interface in oxygen atmospheres  

SciTech Connect

solid oxide fuel cells (SOFCs) are now considered to be one of the most promising systems of highly efficient conversion of fossil energy resources. Most types of SOFCs under development are composed of single cells with stabilized or partially stabilized zirconia (SZ) as the electrolyte, porous nickel-SZ cermet exposed to fuel gas as the anode, and porous perovskite-type La{sub 1{minus}x}Sr(CA){sub x}MnO{sub 3{minus}d} exposed in air or oxygen as the cathode. In order to elucidate how the oxide-ion electron mixed conduction in an oxide cathode affects the kinetics of the cathode reaction in solid oxide fuel cells, a compact La{sub 0.63}Sr{sub 0.27}MnO{sub 3} layer was prepared as a working electrode on the electrolyte of 3 mole percent Y{sub 2}O{sub 3} doped ZrO{sub 2} by a laser flash evaporation method, and electrochemical measurements were made as a function of oxygen partial pressures, P(O{sub 2}), at 700 to 900 C. Contrary to the case of a porous electrode system, the electrode interface conductivity was found to increase with decreasing P(O{sub 2}). With large anodic polarization, the oxide layer was found to be peeled off by oxygen evolution at the electrode/stabilized zirconia interface. The kinetics controlled by chemical diffusion of oxygen in the oxide layer were observed under cathodic polarization with P(O{sub 2}) < 10{sup 4} Pa at 900 C. The oxide ion conductivity in La{sub 0.63}Sr{sub 0.27}MnO{sub 3} was found to be proportional to a{sub O}{sup {minus}1/2}, where a{sub O} is the oxygen activity in the oxide.

Mizusaki, Junichiro [Tohoku Univ., Sendai (Japan). Research Inst. for Scientific Measurements; Saito, Takatoshi, Saito; Tagawa, Hiroaki [Yokohama National Univ. (Japan). Inst. of Environmental Science and Technology

1996-10-01

406

Novel oxygen-carrier materials for chemical-looping combustion and chemical-looping reforming; La x Sr 1? x Fe y Co 1? y O 3? ? perovskites and mixed-metal oxides of NiO, Fe 2O 3 and Mn 3O 4  

Microsoft Academic Search

Solid oxygen-carrier materials for chemical-looping applications have been examined by reduction with CH4 and oxidation with air in a fixed-bed quartz reactor at 900°C. Four perovskite materials, three metal-oxide materials and four metal-oxide mixtures have been studied. It was found that LaxSr1?xFeO3?? perovskites provided very high selectivity towards CO\\/H2 and should be well suited for chemical-looping reforming. Substituting La for

Magnus Rydén; Anders Lyngfelt; Tobias Mattisson; De Chen; Anders Holmen; Erlend Bjørgum

2008-01-01

407

Multicycle study on chemical-looping combustion of simulated coal gas with a CaSO{sub 4} oxygen carrier in a fluidized bed reactor  

SciTech Connect

The cyclic test of a CaSO{sub 4}-based oxygen carrier (natural anhydrite) in alternating reducing simulated coal gas and oxidizing conditions was performed at 950{degree}C in a fluidized bed reactor at atmospheric pressure. A high concentration of CO{sub 2} was obtained in the reduction. The H{sub 2} and CO conversions and CO{sub 2} yield increased initially and final decreased significantly. The release of SO{sub 2} and H{sub 2}S during the cyclic test was found to be responsible for the decrease of reactivity of a CaSO{sub 4} oxygen carrier. The oxygen carrier conversion after the reduction reaction decreased gradually in the cyclic test. Through the comparison of mass-based reaction rates as a function of mass conversion at typical cycles, it was also evident that the reactivity of a CaSO{sub 4} oxygen carrier increased for the initial cycles but finally decreased after around 15 cycles. X-ray diffraction analysis revealed that the presence and intensity of the reduction sulfur species was in accordance with the results of gas conversion. The content of CaO was higher than expected, suggesting the formation of SO{sub 2} and H{sub 2}S during the cycles. Surface morphology analysis demonstrates that the natural anhydrite particle surface varied from impervious to porous after the cyclic test. It was also observed that the small grains on the surface of the oxygen carrier sintered in the cyclic tests. Energy-dispersive spectrum analysis also demonstrated the decrease of oxygen intensity after reduction, and CaO became the main component after the 20th oxidation. Pore structure analysis suggested that the particles agglomerated or sintered in the cyclic tests. The possible method for sulfur mitigation is proposed. Finally, some basic consideration on the design criteria of a CLC system for solid fuels using a CaSO{sub 4} oxygen carrier is discussed by the references and provides direction for future work. 49 refs., 10 figs., 5 tabs.

Qilei Song; Rui Xiao; Zhongyi Deng; Wenguang Zheng; Laihong Shen; Jun Xiao [Southeast University, Nanjing (China). Thermoenergy Engineering Research Institute

2008-11-15

408

Oxygen transfer in membrane bioreactors treating synthetic greywater.  

PubMed

Mass transfer coefficients (k(L)a) were studied in two pilot scale membrane bioreactors (MBR) with different setup configurations treating 200L/h of synthetic greywater with mixed liquor suspended solids' (MLSS) concentrations ranging from 4.7 to 19.5g/L. Besides the MLSS concentration, mixed liquor volatile suspended solids (MLVSS), total solids (TS), volatile solids (VS), chemical oxygen demand (COD) and anionic surfactants of the sludge were measured. Although the pilot plants differed essentially in their configurations and aeration systems, similar alpha-factors at the same MLSS concentration could be determined. A comparison of the results to the published values of other authors showed that not the MLSS concentration but rather the MLVSS concentration seems to be the decisive parameter which influences the oxygen transfer in activated sludge systems operating at a high sludge retention time (SRT). PMID:19217638

Henkel, Jochen; Lemac, Mladen; Wagner, Martin; Cornel, Peter

2009-01-29

409

Screening of physical–chemical methods for removal of organic material, nitrogen and toxicity from low strength landfill leachates  

Microsoft Academic Search

Physical–chemical methods have been suggested for the treatment of low strength municipal landfill leachates. Therefore, applicability of nanofiltration and air stripping were screened in laboratory-scale for the removal of organic matter, ammonia, and toxicity from low strength leachates (NH4-N 74–220 mg\\/l, chemical oxygen demand (COD) 190–920 mg O2\\/l, EC50=2–17% for Raphidocelis subcapitata). Ozonation was studied as well, but with the

S. K Marttinen; R. H Kettunen; K. M Sormunen; R. M Soimasuo; J. A Rintala

2002-01-01

410

Effect of plasma-chemical and thermal treatment in oxygen on the activity of Na3ZrM(PO4)3 phosphates (M = Zn, Co, Cu) in the transformation of butanol-2  

NASA Astrophysics Data System (ADS)

The catalytic properties of plasma-chemically and thermally treated triple zirconium orthophosphates Na3ZrM(PO4)3 (M = Zn, Co, Cu) in the transformation of butanol-2 are studied. X-ray photoelectron spectroscopy data indicate that the surface composition of the samples differs from the stoichiometry, especially in the case of M = Cu. The partial reduction of copper ions occurs during plasma-chemical treatment (PCT), while the amount of Cu on the surface of Na3ZrCu(PO4)3 diminishes. Treatment in an oxygen glow discharge results in a 3-8 times greater yield of the alcohol dehydrogenation product, methyl ethyl ketone. The energy of the alcohol's bonds with the surface is reduced and the dehydration active sites become fully inactivated. In contrast, thermal treatment (TT) results in an increase in the activity of Na3ZrM(PO4)3 in the dehydration of butanol-2.

Pylinina, A. I.; Povarova, E. I.; Mikhalenko, I. I.; Yagodovskaya, T. V.

2013-06-01

411

Analytic study of the chain dark decomposition reaction of iodides - atomic iodine donors - in the active medium of a pulsed chemical oxygen-iodine laser: 1. Criteria for the development of the branching chain dark decomposition reaction of iodides  

SciTech Connect

The scheme of chemical processes proceeding in the active medium of a pulsed chemical oxygen-iodine laser (COIL) is analysed. Based on the analysis performed, the complete system of differential equations corresponding to this scheme is replaced by a simplified system of equations describing in dimensionless variables the chain dark decomposition of iodides - atomic iodine donors, in the COIL active medium. The procedure solving this system is described, the basic parameters determining the development of the chain reaction are found and its specific time intervals are determined. The initial stage of the reaction is analysed and criteria for the development of the branching chain decomposition reaction of iodide in the COIL active medium are determined. (active media)

Andreeva, Tamara L; Kuznetsova, S V; Maslov, Aleksandr I; Sorokin, Vadim N [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2009-02-28

412

Appreciating Oxygen  

ERIC Educational Resources Information Center

|Photosynthetic flora and microfauna utilize light from the sun to convert carbon dioxide and water into carbohydrates and oxygen. While these carbohydrates and their derivative hydrocarbons are generally considered to be fuels, it is the thermodynamically energetic oxygen molecule that traps, stores, and provides almost all of the energy that…

Weiss, Hilton M.

2008-01-01

413

Travel Demand Modeling  

SciTech Connect

This chapter describes the principal types of both passenger and freight demand models in use today, providing a brief history of model development supported by references to a number of popular texts on the subject, and directing the reader to papers covering some of the more recent technical developments in the area. Over the past half century a variety of methods have been used to estimate and forecast travel demands, drawing concepts from economic/utility maximization theory, transportation system optimization and spatial interaction theory, using and often combining solution techniques as varied as Box-Jenkins methods, non-linear multivariate regression, non-linear mathematical programming, and agent-based microsimulation.

Southworth, Frank [ORNL; Garrow, Dr. Laurie [Georgia Institute of Technology

2011-01-01

414

Energy demand forecasting  

NASA Astrophysics Data System (ADS)

Energy demand forecasting and its connection with national energy policies and decisions is examined in light of recent, sharply revised estimates of future energy requirements. Techniques of economic projects are examined. Modeling of energy demands is discussed. Renewable energy sources are discussed. The shift away from reliance of domestic users on oil and natural gas toward electricity as a primary energy resource is examined in the context of the need to conserve energy and expand generating capacity in order to avoid a significant electricity shortfall.

415

Electronic structure of an oxygen vacancy in Al{sub 2}O{sub 3} from the results of Ab Initio quantum-chemical calculations and photoluminescence experiments  

SciTech Connect

The electronic structure of an oxygen vacancy in {alpha}-Al{sub 2}O{sub 3} and {gamma}-Al{sub 2}O{sub 3} is calculated. The calculation predicts an absorption peak at an energy of 6.4 and 6.3 eV in {alpha}-Al{sub 2}O{sub 3} and {gamma}-Al{sub 2}O{sub 3}, respectively. The luminescence and luminescence excitation spectra of amorphous Al{sub 2}O{sub 3} are measured using synchrotron radiation. The presence of a luminescence band at 2.9 eV and a peak at 6.2 eV in the luminescence excitation spectrum indicates the presence of oxygen vacancies in amorphous Al{sub 2}O{sub 3}.

Pustovarov, V. A. [Ural State Technical University (Russian Federation); Aliev, V. Sh.; Perevalov, T. V., E-mail: timson@isp.nsc.ru; Gritsenko, V. A., E-mail: grits@isp.nsc.ru [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Branch (Russian Federation); Eliseev, A. P. [Russian Academy of Sciences, Institute of Geology and Mineralogy, Siberian Branch (Russian Federation)

2010-01-15

416

Theoretical investigation of hydrogen bonding effects on oxygen, nitrogen, and hydrogen chemical shielding and electric field gradient tensors of chitosan\\/HI salt  

Microsoft Academic Search

A density functional theory study has been carried out to calculate the 17O, 15N, 13C, and 1H chemical shielding as well as 17O, 14N, and 2H electric field gradient tensors of chitosan\\/HI type I salt. These calculations were performed using the B3LYP functional and 6-311++G (d,p) and 6-31++G (d,p) basis sets. Calculated EFG and chemical shielding tensors were used to

Sajjad Khodaei; Nasser L. Hadipour; Mohammad Reza Kasaai

2007-01-01

417

Lone pair ??? ? interactions between water oxygens and aromatic residues: Quantum chemical studies based on high-resolution protein structures and model compounds  

PubMed Central

The ? electron cloud of aromatic centers is known to be involved in several noncovalent interactions such as C—H···?, O—H···?, and ?···? interactions in biomolecules. Lone-pair (lp) ··· ? interactions have gained attention recently and their role in biomolecular structures is being recognized. In this article, we have carried out systematic analysis of high-resolution protein structures and identified more than 400 examples in which water oxygen atoms are in close contact (distance < 3.5 Å) with the aromatic centers of aromatic residues. Three different methods were used to build hydrogen atoms and we used a consensus approach to find out potential candidates for lp···? interactions between water oxygen and aromatic residues. Quantum mechanical calculations at MP2/6-311++G(d,p) level on model systems based on protein structures indicate that majority of the identified examples have energetically favorable interactions. The influence of water hydrogen atoms was investigated by sampling water orientations as a function of two parameters: distance from the aromatic center and the angle between the aromatic plane and the plane formed by the three water atoms. Intermolecular potential surfaces were constructed using six model compounds representing the four aromatic amino acids and 510 different water orientations for each model compound. Ab initio molecular orbital calculations at MP2/6-311++G(d,p) level show that the interaction energy is favorable even when hydrogen atoms are farthest from the aromatic plane while water oxygen is pointing toward the aromatic center. The strength of such interaction depends upon the distance of water hydrogen atoms from the aromatic substituents. Our calculations clearly show that the lp···? interactions due to the close approach of water oxygen and aromatic center are influenced by the positions of water hydrogen atoms and the aromatic substituents.

Jain, Alok; Ramanathan, Venkatnarayan; Sankararamakrishnan, Ramasubbu

2009-01-01

418

High temperature properties of La 0.6Sr 0.4Co 0.8Fe 0.2O 3? ? oxygen nonstoichiometry and chemical diffusion constant  

Microsoft Academic Search

Oxygen nonstoichiometry and oxide ion diffusion constant of La0.6Sr0.4Co0.8Fe0.2O3?? were gravimetrically studied with a CAHN1000 thermal balance, at temperatures 973–1073 K, with PO2 between 1 and 105 Pa. The weight relaxation was mainly determined by bulk diffusion, but also influenced by surface exchange reaction. Diffusion coefficients were obtained by fitting the experimental data to the solution of the diffusion equation.

Masatoshi Katsuki; Shaorong Wang; Masayuki Dokiya; Takuya Hashimoto

2003-01-01

419

Chemical Pathways of Peptide Degradation. VIII. Oxidation of Methionine in Small Model Peptides by Prooxidant\\/Transition Metal Ion Systems: Influence of Selective Scavengers for Reactive Oxygen Intermediates  

Microsoft Academic Search

In the presence of oxygen, Fe(III), and an appropriate electron donor (e.g. ascorbic acid, dithiothreitol), the oxidation of methionine residues to methionine sulfoxides in small model peptides can be induced. It is shown in this study that these oxidations can be retarded by catalase in a pH-dependent manner, by some hydroxyl radical scavengers, and by azide. In contrast, superoxide dismutase

Shihong Li; Christian Schöneich; Ronald T. Borchardt

1995-01-01

420

Structure determination for saturated (1×1) oxygen on W(110) from full solid angle photoelectron diffraction with chemical-state resolution  

Microsoft Academic Search

The local atomic geometry of oxygen adsorbed in a stable one monolayer (1×1) structure on W(110) has been determined for the first time from full solid angle site-resolved photoelectron diffraction (PD). This structure also exhibits an additional (1×12) periodicity, but PD allows determination of the local structure within this periodicity. The data were obtained with a new beamline and experimental

R. X. Ynzunza; F. J. Palomares; E. D. Tober; Z. Wang; J. Morais; R. Denecke; H. Daimon; Y. Chen; Z. Hussain; M. A. Van Hove; C. S. Fadley

1999-01-01

421

ACTIVE MEDIA Nonequilibrium population of the first vibrational level of O2(1?) molecules in O2 — O2(1?) — H2O gas flow at the output of chemical singlet-oxygen generator  

NASA Astrophysics Data System (ADS)

The concentrations of electron-excited particles have been determined by measuring the absolute spectral irradiance in the range of 600 — 800 nm of O2 — O2(1?) — H2O gas mixture at the output of a chemical singlet-oxygen generator (SOG). A nonequilibrium population of the first vibrational level of O2(1?) molecules has been clearly observed and found to depend on the water vapour content. In correspondence with the results of these measurements and according to the analysis of kinetics processes in the O2 — O2(1?) — H2O mixture, the maximum number of vibrational quanta generated in the O2(1?) + O2(1?) ? O2(1?) + O2(3?) reaction is 0.05 ± 0.03. It is concluded that the vibrational population of O2(1?) at the output of the SOG used in a chemical oxygen—iodine laser is close to thermal equilibrium value.

Zagidullin, M. V.

2010-11-01

422

Distribution of Childrearing Demands.  

ERIC Educational Resources Information Center

The tools of economic analysis were applied to demographic data in order to develop a social indicator measuring the extent of inequality in the distribution of childrearing responsibility in households from 1940 to 1980. With data drawn from the Current Population Survey of the Bureau of the Census, a "demand intensity" measure was developed.…

Zimmerman, Judith D.; And Others

423

Demanding Divestment from Sudan  

ERIC Educational Resources Information Center

Bowing to student demands to "stop supporting genocide," the University of California regents voted earlier this year to divest millions of dollars from companies working in the war-torn African nation of Sudan, the first major public university in the nation to take such action. Since student protests on the subject began at Harvard University in…

Asquith, Christina

2006-01-01

424

Identifying Unmet Demand  

Microsoft Academic Search

Brand preferences and marketplace demand are a reflection of the importance of underlying needs of consumers and the efficacy of product attributes for delivering value. Dog owners, for example, may look to dog foods to provide specific benefits for their pets (e.g., shiny coats) that may not be available from current offerings. An analysis of consumer wants for these consumers

Sandeep R. Chandukala; Yancy D. Edwards; Greg M. Allenby

2011-01-01

425

Commercial Sector Demand Module  

EIA Publications

Documents the objectives, analytical approach and development of the National Energy Modeling System (NEMS) Commercial Sector Demand Module. The report catalogues and describes the model assumptions, computational methodology, parameter estimation techniques, model source code, and forecast results generated through the synthesis and scenario development based on these components.

Kevin Jarzomski

2013-10-10

426

Commercial Sector Demand Module  

EIA Publications

Documents the objectives, analytical approach and development of the National Energy Modeling System (NEMS) Commercial Sector Demand Module. The report catalogues and describes the model assumptions, computational methodology, parameter estimation techniques, model source code, and forecast results generated through the synthesis and scenario development based on these components.

Kevin Jarzomski

2012-11-15

427

Demand-side management  

Microsoft Academic Search

Power utilities worldwide are under mounting pressure to ensure that power system development is environmentally friendly. Demand-side management (DSM) programme is viewed as the least-cost energy resource when both environmental costs and welfare needs are taken into account. It is a utility financed programme for total energy savings approach to reducing peak and base loads. It introduces a new element

Maimunah Ibrahim; M. Z. Jaafar; M. R. A. Ghani

1993-01-01

428

Demand, Growth, and Evolution  

ERIC Educational Resources Information Center

|The paradigm shift to engaged and collaborative learning delivered via distance education technologies has been led by practitioners in adult and continuing education. Online and blended courses are experiencing increased demand and continued growth at all levels of higher education, professional development, and K-12 education. Adult and…

Hoskins, Barbara

2011-01-01

429

Demand functions and reflexivity  

NASA Astrophysics Data System (ADS)

In the theory of ordered spaces and in microeconomic theory two important notions, the notion of the base for a cone which is defined by a continuous linear functional and the notion of the budget set are equivalent. In economic theory the maximization of the preference relation of a consumer on any budget set defines the demand correspondence which at any price vector indicates the preferred vectors of goods and this is one of the fundamental notions of this theory. Contrary to the finite-dimensional economies, in the infinite-dimensional ones, the existence of the demand correspondence is not ensured. In this article we show that in reflexive spaces (and in some other classes of Banach spaces), there are only two classes of closed cones, i.e. cones whose any budget set is bounded and cones whose any budget set is unbounded. Based on this dichotomy result, we prove that in the first category of these cones the demand correspondence exists and that it is upper hemicontinuous. We prove also a characterization of reflexive spaces based on the existence of the demand correspondences.

Polyrakis, Ioannis A.

2008-02-01

430

Home Oxygen Therapy  

MedlinePLUS

... common ways of providing home oxygen therapy: A liquid oxygen system; A standard oxygen concentrator, and A ... home oxygen is examined in more detail below. Liquid Oxygen – Oxygen is stored as a very cold ...

431

Effects of oxygen on biodegradation of benzoate and 3-chlorobenzoate in a denitrifying chemostat.  

PubMed

A mixed microbial culture degraded a mixture of benzoate (863 mg/L), 3-chlorobenzoate (3-CB) (69.7 mg/L), and pyruvate (244 mg/L) under denitrifying conditions in a chemostat. Biodegradation under denitrifying conditions was stable, complete (effluent concentrations below detection limits), and proceeded without the production of toxic intermediates like chlorocatechols. The addition of oxygen at mass input rates of 6.2%, 15.5%, and 43.9% of the mass input rate of chemical oxygen demand (COD) (337 mg COD/h) did not induce the synthesis of aerobic biodegradation pathways and thus did not disrupt biodegradation. Rather, the oxygen was used as a terminal electron acceptor, displacing a stoichiometric amount of nitrate, leading to microaerobic conditions (dissolved oxygen concentration <0.050 mg/L) in which oxygen utilization and denitrification occurred simultaneously. The reduction of nitrate occurred fully to N(2) gas with no accumulation of nitrite, nitrous oxide, or nitric oxide, although the ability of the culture to transfer electrons to the nitrogen oxides decreased as the oxygen input was increased. The anoxic benzoate uptake capability was unaffected by the increase in oxygen addition, but the anoxic 3-CB uptake capability increased, as did the level of benzoyl-CoA reductase in the cells. PMID:15556227

Deniz, Timur; Cinar, Ozer; Grady, C P Leslie

2004-12-01

432

Oxygen release kinetics from solid phase oxygen in Arctic Alaska.  

PubMed

Child's Pad is a gravel construction surface that was contaminated with petroleum during oil-field service operations in Deadhorse, Alaska. As part of a remedial action plan, a buffer strip of uncontaminated sandy gravel was placed along sections of the pad boundary. A magnesium peroxide formulation manufactured by Regenesis, and sold as Oxygen Release Compound (ORC), was placed in the buffer strips. The ORC was intended to supply oxygen to aerobic microorganisms capable of degrading petroleum. Studies were conducted in the laboratory to determine initial oxygen release kinetics from ORC in contact with barrier soil. Studies quantified the biotic and abiotic catalytic mechanisms for converting hydrogen peroxide (a possible MgO2 intermediate) and ORC to oxygen and water, the effects of temperature on oxygen release from ORC, and the effect of field exposure on ORC viability. Barrier soil exhibited sufficient catalytic activity to convert hydrogen peroxide to oxygen faster than the expected biological demand. The oxygen evolution rate (OER) from ORC was lower at 7 degrees C than 21 degrees C by more than two times. The ORC recovered from Child's Pad after less than 1 year retained nearly all of the original available oxygen, although physical bridging was evident. PMID:10337396

Schmidtke, T; White, D; Woolard, C

1999-01-29

433

Investigation of chemical looping combustion by solid fuels. 2. redox reaction kinetics and product characterization with coal, biomass, and solid waste as solid fuels and CuO as an oxygen carrier  

SciTech Connect

This paper is the second in a series of two on the investigation of the chemical looping combustion (CLC) of solid fuels. The first paper put forward the concept of the CLC of solid fuels using a circulating fluidized bed as a reactor and Cu-CuO as the oxygen carrier, which was based on an analysis of oxygen transfer capability, reaction enthalpy, and chemical equilibrium. In this second paper, we report the results of the evaluation of the reduction of CuO reduced by solid fuels such as coal and some other 'opportunity' solid fuels. Tests on the reduction of CuO by the selected solid fuels were conducted using simultaneous differential scanning calorimetry and thermogravimetric analysis, which simulates a microreactor. An attached mass spectrometer (MS) was used for the characterization of evolved gaseous products. The X-ray diffractometer (XRD) and scanning electron microscope (SEM) were used for the characterization of the solid residues. Results strongly supported the feasibility of CuO reduction by selected solid fuels. CuO can be fully converted into Cu in a reduction process, either in a direct path by solid fuels, which was verified by MS analysis under a N{sub 2} atmosphere, or in an indirect path by pyrolysis and gasification products of solid fuels in the reducer. No Cu{sub 2}O exists in reducing atmospheres, which was characterized by an XRD analysis and mass balance calculations. No carbon deposit was found on the surface of the reduced Cu, which was characterized by SEM analysis. CuO reduction by solid fuels can start at temperatures as low as approximately 500 C. Tests indicated that the solid fuels with higher reactivity (higher volatile matter) would be desirable for the development of the chemical looping combustion process of solid fuels, such as sub-bituminous Powder River Basin coal and solid waste and biomass. 4 refs., 12 figs., 3 tabs.

Yan Cao; Bianca Casenas; Wei-Ping Pan [Western Kentucky University, Bowling Green, KY (United States). Institute for Combustion Science and Environmental Technology

2006-10-15

434

Oxygen transport by hemoglobin.  

PubMed

Hemoglobin (Hb) constitutes a vital link between ambient O2 availability and aerobic metabolism by transporting oxygen (O2) from the respiratory surfaces of the lungs or gills to the O2-consuming tissues. The amount of O2 available to tissues depends on the blood-perfusion rate, as well as the arterio-venous difference in blood O2 contents, which is determined by the respective loading and unloading O2 tensions and Hb-O2-affinity. Short-term adjustments in tissue oxygen delivery in response to decreased O2 supply or increased O2 demand (under exercise, hypoxia at high altitude, cardiovascular disease, and ischemia) are mediated by metabolically induced changes in the red cell levels of allosteric effectors such as protons (H(+)), carbon dioxide (CO2), organic phosphates, and chloride (Cl(-)) that modulate Hb-O2 affinity. The long-term, genetically coded adaptations in oxygen transport encountered in animals that permanently are subjected to low environmental O2 tensions commonly result from changes in the molecular structure of Hb, notably amino acid exchanges that alter Hb's intrinsic O2 affinity or its sensitivity to allosteric effectors. Structure-function studies of animal Hbs and human Hb mutants illustrate the different strategies for adjusting Hb-O2 affinity and optimizing tissue oxygen supply. PMID:23798307

Mairbäurl, Heimo; Weber, Roy E

2012-04-01

435

Quadriceps oxygenation during isometric exercise in sailing.  

PubMed

The aim of the present study was to investigate why blood lactate after prolonged quadriceps contraction during hiking is only marginally increased. Eight sailors performed five 3-min hiking bouts interspersed with 5-s recovery periods. Whole body oxygen uptake, heart rate and lactate were recorded, along with continuous-wave near-infrared spectroscopy measures of quadriceps oxygenation. The time for 50% re-oxygenation was also assessed as an indication of the degree of localized oxygen delivery stress. Hiking elicited a significant (p = 0.001) increase in mean (+/- SD) heart rate (124 +/- 10 beats . min (-1)) which was accompanied by a disproportionately low oxygen uptake (12 +/- 2 ml.kg(-1).min(-1)). Lactate was significantly (p = 0.001) increased throughout hiking manoeuvres, though post-exercise it remained low (3.2 +/- 0.9 mmol.l(-1)). During the hiking bouts mean quadriceps oxygenation was significantly (p = 0.001) reduced compared to baseline (by 33 +/- 5%), indicating an imbalance between muscle oxygen accessibility and oxygen demand. During rest intervals quadriceps oxygenation was partially restored. After the end of the final bout the time for 50 % re-oxygenation was only 8 +/- 2 s, whereas recovery of quadriceps oxygenation and oxygen uptake was completed within 3 min. We conclude that the observed low lactate could be attributed to the small oxygen and energy deficits during hiking as the muscles' oxygen accessibility is presumably partially restored during the brief rest intervals. PMID:17614020

Vogiatzis, I; Tzineris, D; Athanasopoulos, D; Georgiadou, O; Geladas, N

2007-07-05

436

The Demand for the Arts  

Microsoft Academic Search

This paper discusses the demand for the arts from a theoretical and an empirical perspectives. We suggest that the demand for the arts is price elastic and that art is a luxury good. Education, and learning experiences are also important factors affecting that demand. Ce texte traite de la demande pour les arts d'un point de vue théorique et empirique.

Louis Lévy-Garboua; Claude Montmarquette

2002-01-01

437

Erythropoiesis-stimulating agents and other methods to enhance oxygen transport  

Microsoft Academic Search

Oxygen is essential for life, and the body has developed an exquisite method to collect oxygen in the lungs and transport it to the tissues. Hb contained within red blood cells (RBCs), is the key oxygen-carrying component in blood, and levels of RBCs are tightly controlled according to demand for oxygen. The availability of oxygen plays a critical role in

S Elliott

2008-01-01

438

Atrophy in metal demand  

SciTech Connect

What appears to be a major structural change with serious implications for all of the major metal industries has in many quarters gone largely unnoticed. This change, which apparently took place about 1974, shortly after the first major oil crisis, involves a sharp break or discontinuity in the growth of world demand for metals. Its magnitude is high-lighted by the graphs which show the rise in world consumption, outside the socialist countries, for the major metals since 1950. Indeed, growth in consumption has not only slowed, it has for many metals ground to a halt over the last decade. The graphs also illustrate what consumption would have been in the post 1974 period had earlier growth trends been sustained. The large gaps between the actual and the trend figures indicate that much of the distress suffered by the major metal industries in recent years can be attributed to the slowdown in the growth of demand. 13 references, 1 figure, 1 table.

Tilton, J.E.

1986-01-01

439

Household Consumer Credit Demand  

Microsoft Academic Search

Since the mid 1980s consumer credit has grown rapidly in most European countries. However, the amounts borrowed by households\\u000a as a proportion of income differ widely from country to country. These differences can be ascribed to a variety of factors,\\u000a some of which have been extensively analysed in the literature,1 that influence the demand for and supply of credit and,

Daniela Vandone

440

CUMULATIVE OXYGEN ABUNDANCES OF SPIRAL GALAXIES  

SciTech Connect

Studying the global evolution of spiral galaxies requires determining their overall chemical compositions. However, since spirals tend to possess gradients in their chemical compositions, determining their overall chemical abundances poses a challenge. In this study, the framework for a newly proposed method for determining the overall oxygen abundance of a disk is established. By separately integrating the absolute amounts of hydrogen and oxygen out to large radii, the cumulative oxygen abundance is shown to approach an asymptotic value. In this manner, a reliable account of the overall chemical state of a disk is revealed.

Dack, Stuart; McCall, Marshall L., E-mail: studack@alumni.yorku.ca, E-mail: mccall@yorku.ca [Department of Physics and Astronomy, York University, 4700 Keele Street, Toronto, ON M3J 1P3 (Canada)

2012-05-10

441

Cumulative Oxygen Abundances of Spiral Galaxies  

NASA Astrophysics Data System (ADS)

Studying the global evolution of spiral galaxies requires determining their overall chemical compositions. However, since spirals tend to possess gradients in their chemical compositions, determining their overall chemical abundances poses a challenge. In this study, the framework for a newly proposed method for determining the overall oxygen abundance of a disk is established. By separately integrating the absolute amounts of hydrogen and oxygen out to large radii, the cumulative oxygen abundance is shown to approach an asymptotic value. In this manner, a reliable account of the overall chemical state of a disk is revealed.

Dack, Stuart; McCall, Marshall L.

2012-05-01

442

Reduction of COD and removal of Zn 2+ from rayon industry wastewater by combined electro-Fenton treatment and chemical precipitation  

Microsoft Academic Search

In this study a stepwise combination of electro-Fenton process and chemical precipitation was used to treat rayon industry wastewater and reduce its chemical oxygen demand (COD) and Zn2+. Results obtained with industrial wastewater having a COD of 2400mg\\/L and 32mg\\/L Zn2+ revealed that approximately 88% COD was reduced in 50min using the electro-Fenton method with an optimized H2O2 dose of

Prabir Ghosh; Amar Nath Samanta; Subhabrata Ray

2011-01-01

443

Evaluation of lead and COD removal from lead octoate drier effluent by chemical precipitation, coagulation–flocculation, and potassium persulfate oxidation processes  

Microsoft Academic Search

A range of treatment processes for the removal of mineral and organic pollutants from industrial wastewater have been investigated. This study was aimed to remove lead, turbidity, and chemical oxygen demand (COD) from lead octoate drier wastewater via potassium persulfate oxidation in the presence of UV and heat, chemical precipitation by sulfuric acid, and coagulation–flocculation processes. Al2(SO4)3, poly-aluminum chloride (PAC),

Anahita Rabii; Gholamreza Nabi Bidhendi; Naser Mehrdadi

2012-01-01

444

ELEMENTS OF LASER SETUPS: Parameters of an electric-discharge generator of iodine atoms for a chemical oxygen—iodine laser  

NASA Astrophysics Data System (ADS)

Laser-induced fluorescence is used for measuring the concentration of iodine molecules at the output of an electric-discharge generator of atomic iodine. Methyl iodide CH3I is used as the donor of atomic iodine. The fraction of iodine extracted from CH3I in the generator is ~50%. The optimal operation regimes are found in which 80%—90% of iodine contained in the output flow of the generator was in the atomic state. This fraction decreased during the iodine transport due to recombination and was 20%—30% at the place where iodine was injected into the oxygen flow. The fraction of the discharge power spent for dissociation was ~3%.

Azyazov, V. N.; Vorob'ev, M. V.; Voronov, A. I.; Kupryaev, Nikolai V.; Mikheev, P. A.; Ufimtsev, N. I.

2009-01-01

445

Modeling the liquid-phase oxidation of hydrocarbons over a range of temperatures and dissolved oxygen concentrations with pseudo-detailed chemical kinetics  

Microsoft Academic Search

The ability of pseudo-detailed chemical kinetic modeling to simulate the oxidation behavior of Exxsol D-80, a paraffin blend whose oxidative characteristics are representative of severely hydrotreated jet fuels, is assessed. The effects of temperature and initial dissolved O2 concentration on oxidation are considered. A 17-step pseudo-detailed mechanism is shown to provide reasonable simulations of Exxsol D-80 oxidation over a range

Nicholas J. Kuprowicz; Jamie S. Ervin; Steven Zabarnick

2004-01-01

446

On the nitrogen and oxygen incorporation in plasma-enhanced chemical vapor deposition (PECVD) SiO x N y films  

Microsoft Academic Search

Silicon oxynitride films were deposited by plasma-enhanced chemical vapor deposition at low temperatures using nitrous oxide (N2O) and silane (SiH4) as gas precursors. The influence of the N2O\\/SiH4 flow ratio (varied from 0.25 up to 5) and the thickness of the films on the optical and structural properties of the material was analyzed. The films were characterized by ellipsometry, Fourier-transform

M. I Alayo; I Pereyra; W. L Scopel; M. C. A Fantini

2002-01-01

447

The use of a housecleaning product in an indoor environment leading to oxygenated polar compounds and SOA formation: Gas and particulate phase chemical characterization  

NASA Astrophysics Data System (ADS)

This work investigates Secondary Organic Aerosol (SOA) formed by limonene ozonolysis using a housecleaning product in indoor environment. This study combines simulation chamber ozonolysis experiments and field studies in an experimental house allowing different scenarios of housecleaning product use in real conditions. Chemical speciation has been performed using a new method based on simultaneous sampling of both gas and particulate phases on sorbent tubes and filters. This method allowed the identification and quantification of about 35 products in the gas and particulate phases. Among them, products known to be specific from limonene ozonolysis such as limononaldehyde, ketolimonene and ketolimonic acid have been detected. Some other compounds such as 2-methylbutanoic acid had never been detected in previous limonene ozonolysis studies. Some compounds like levulinic acid had already been detected but their formation remained unexplained. Potential reaction pathways are proposed in this study for these compounds. For each experiment, chemical data are coupled together with physical characterization of formed particles: mass and size and number distribution evolution which allowed the observation of new particles formation (about 87,000 particle cm-3). The chemical speciation associated to aerosol size distribution results confirmed that limonene emitted by the housecleaning product was responsible for SOA formation. To our knowledge, this work provides the most comprehensive analytical study of detected compounds in a single experiment for limonene ozonolysis in both gaseous and particulate phases in real indoor environment.

Rossignol, S.; Rio, C.; Ustache, A.; Fable, S.; Nicolle, J.; Même, A.; D'Anna, B.; Nicolas, M.; Leoz, E.; Chiappini, L.

2013-08-01

448

Physiological demands of downhill mountain biking.  

PubMed

Mountain biking is a popular recreational pursuit and the physiological demands of cross-country style riding have been well documented. However, little is known regarding the growing discipline of gravity-assisted downhill cycling. We characterised the physiological demands of downhill mountain biking under typical riding conditions. Riding oxygen consumption (VO(2)) and heart rate (HR) were measured on 11 male and eight female experienced downhill cyclists and compared with data during a standardised incremental to maximum (VO(2max)) exercise test. The mean VO(2) while riding was 23.1 ± 6.9 ml · kg(-1) · min(-1) or 52 ± 14% of VO(2max) with corresponding heart rates of 146 ± 11 bpm (80 ± 6% HRmax). Over 65% of the ride was in a zone at or above an intensity level associated with improvements in health-related fitness. However, the participants' heart rates and ratings of perceived exertion were artificially inflated in comparison with the actual metabolic demands of the downhill ride. Substantial muscular fatigue was evident in grip strength, which decreased 5.4 ± 9.4 kg (5.5 ± 11.2%, P = 0.03) post-ride. Participation in downhill mountain biking is associated with significant physiological demands, which are in a range associated with beneficial effects on health-related fitness. PMID:23025296

Burr, Jamie F; Drury, C Taylor; Ivey, Adam C; Warburton, Darren E R

2012-10-02

449

Isotopic exchange in mineral-fluid systems. 4. The crystal chemical controls on oxygen isotope exchange rates in carbonate-H{sub 2}O and layer silicate-H{sub 2}O systems  

SciTech Connect

Oxygen isotope exchange between minerals and water in systems far from chemical equilibrium is controlled largely by surface reactions such as dissolution-precipitation. In many cases, this behavior can be modeled adequately by a simple pseudo-first order rate model that accounts for changes in surface area of the solid. Previous modeling of high temperature isotope exchange data for carbonates, sulfates, and silicates indicated that within a given mineral group there appears to be a systematic relationship between rate and mineral chemistry. The author tested this idea by conducting oxygen isotope exchange experiments in the systems, carbonate-H{sub 2}O and layer silicate-H{sub 2}O at 300 and 350 C, respectively. Witherite (BaCO{sub 3}), strontianite (SrCO{sub 3}) and calcite (CaCO{sub 3}) were reacted with pure H{sub 2}O for different lengths of time (271--1,390 H) at 300 C and 100 bars. The layer silicates, chlorite, biotite and muscovite were reacted with H{sub 2}O for durations ranging from 132 to 3,282 h at 350 C and 250 bars. A detailed survey of grain sizes and grain habits using scanning electron microscopy (SEM) indicated that grain regrowth occurred in all experiments to varying extents. The isotopic rates (ln r) for the carbonate-H{sub 2}O system are {minus}20.75 {+-} 0.44, {minus}18.95 {+-} 0.62 and {minus}18.51 {+-} 0.48 mol O/m{sup 2} s for calcite, strontianite and witherite, respectively. The oxygen isotope exchange rates for layer silicate-H{sub 2}O systems are {minus}23.99 {+-} 0.89, {minus}23.14 {+-} 0.74 and {minus}22.40 {+-} 0.66 mol O/m{sup 2} s for muscovite, biotite and chlorite, respectively.

Cole, D.R.

2000-03-01

450