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1

Oxygen-Enhanced Combustion: Theory and Applications  

Microsoft Academic Search

In the broadest sense, oxygen-enhanced combustion (OEC) refers to the use of oxygen to improve combustion and\\/or process characteristics. When a stream of oxygen is available, a wide range of flame configurations is possible. This work considers two specific configurations of OEC and is divided into two parts. In Part I, fundamental experimental and numerical flame studies explore the combustion

Scott Skeen

2009-01-01

2

OXYGEN ENHANCED COMBUSTION FOR NOx CONTROL  

Microsoft Academic Search

Conventional wisdom says adding oxygen to a combustion system enhances product throughput, system efficiency, and, unless special care is taken, increases NOx emissions. This increase in NOx emissions is typically due to elevated flame temperatures associated with oxygen use leading to added thermal NOx formation. Innovative low flame temperature oxy-fuel burner designs have been developed and commercialized to minimize both

David R. Thompson; Lawrence E. Bool; Jack C. Chen

2004-01-01

3

OXYGEN ENHANCED COMBUSTION FOR NOx CONTROL  

SciTech Connect

This quarterly technical progress report will summarize work accomplished for the Program through the thirteenth quarter, April-June 2003, in the following task areas: Task 1--Oxygen Enhanced Combustion, Task 3--Economic Evaluation and Task 4--Program Management. The program is proceeding in accordance with project objectives. REI's model was modified to evaluate mixing issues in the upper furnace of a staged unit. Analysis of the results, and their potential application to this unit is ongoing. Economic evaluation continues to confirm the advantage of oxygen-enhanced combustion. A contract for a commercial demonstration has been signed with the Northeast Generation Services Company to supply oxygen and license the oxygen enhanced low NOx combustor technology for use at the 147-megawatt coal fired Mt. Tom Station in Holyoke, MA. Commercial proposals have been submitted. Economic analysis of a beta site test performance was conducted.

David R. Thompson; Lawrence E. Bool; Jack C. Chen

2003-08-01

4

OXYGEN ENHANCED COMBUSTION FOR NOx CONTROL  

SciTech Connect

This quarterly technical progress report will summarize work accomplished for the Program through the second quarter July--September 2000 in the following task areas: Task 1-Oxygen Enhanced Combustion, Task 2-Oxygen Transport Membranes and Task 4-Program Management. The program is proceeding in accordance with the objectives for the first year. OTM tube characterization is well underway, the design and assembly of the high pressure permeation test facility is complete and the facility will be in full operation during the next quarter. Combustion testing has been initiated at both the University of Arizona and Praxair. Testing at the University of Arizona has experienced some delays; steps have been take to get the test work back on schedule. Completion of the first phase of the testing is expected in next quarter. Combustion modeling has been started at both REI and Praxair, preliminary results are expected in the next quarter.

Lawrence E. Bool; Jack C. Chen; David R. Thompson

2000-10-01

5

OXYGEN ENHANCED COMBUSTION FOR NOx CONTROL  

Microsoft Academic Search

Increased environmental regulations will require utility boilers to reduce NOâ emissions to less than 0.15lb\\/MMBtu in the near term. Conventional technologies such as Selective Catalytic Reduction (SCR) and Selective Non-Catalytic Reduction (SNCR) are unable to achieve these lowered emission levels without substantially higher costs and major operating problems. Oxygen enhanced combustion is a novel technology that allows utilities to meet

Lawrence E. Bool; Jack C. Chen; David R. Thompson

2000-01-01

6

OXYGEN ENHANCED COMBUSTION FOR NOx CONTROL  

SciTech Connect

This quarterly technical progress report will summarize work accomplished for the Program through the twelfth quarter, January-March 2003, in the following task areas: Task 1--Oxygen Enhanced Combustion, Task 2--Oxygen Transport Membranes, Task 3--Economic Evaluation and Task 4--Program Management. The program is proceeding in accordance with the objectives for the third year. Pilot scale experiments conducted at the University of Utah explored both the effectiveness of oxygen addition and the best way to add oxygen with a scaled version of Riley Power's newest low NOx burner design. CFD modeling was done to compare the REI's modeling results for James River Unit 3 with the NOx and LOI results obtained during the demonstration program at that facility. Investigation of an alternative method of fabrication of PSO1d elements was conducted. OTM process development work has concluded with the completion of a long-term test of a PSO1d element Economic evaluation has confirmed the advantage of oxygen-enhanced combustion. Proposals have been submitted for two additional beta test sites. Commercial proposals have been submitted. Economic analysis of a beta site test performance was conducted.

David R. Thompson; Lawrence E. Bool; Jack C. Chen

2003-04-01

7

High-Efficiency, High-Capacity, Low-NOx Aluminum Melting Using Oxygen-Enhanced Combustion  

Microsoft Academic Search

This report describes the development and application of a novel oxygen enhanced combustion system with an integrated vacuum swing adsorption (VSA) oxygen supply providing efficient, low NOx melting in secondary aluminum furnaces. The mainstay of the combustion system is a novel air-oxy-natural gas burner that achieves high productivity and energy efficiency with low NOx emissions through advanced mixing concepts and

DAgostini

2000-01-01

8

High-Efficiency, High-Capacity, Low-NOx Aluminum Melting Using Oxygen-Enhanced Combustion. Final Report, October 1, 1997-March 31, 2000.  

National Technical Information Service (NTIS)

This report describes the development and application of a novel oxygen enhanced combustion system with an integrated vacuum swing adsorption (VSA) oxygen supply providing efficient, low NOx melting in secondary aluminum furnaces. The mainstay of the comb...

M. D. D'Aostini

2000-01-01

9

On combustion enhancement mechanisms in the case of electrical-discharge-excited oxygen molecules  

Microsoft Academic Search

Combustion intensification mechanisms in a supersonic flow of a hydrogen-oxygen mixture behind the oblique shock wave front are investigated for the case when vibrations and the a 1Deltag and b 1Sigma{g\\/+} electron states of a O2 molecule are excited by an electrical discharge. The presence of vibrationally excited and electronically excited O2 molecules in the oxygen plasma allows intensification of

A. M. Starik; B. I. Lukhovitskii; V. V. Naumov; N. S. Titova

2007-01-01

10

On combustion enhancement mechanisms in the case of electrical-discharge-excited oxygen molecules  

Microsoft Academic Search

Combustion intensification mechanisms in a supersonic flow of a hydrogen-oxygen mixture behind the oblique shock wave front\\u000a are investigated for the case when vibrations and the a\\u000a 1?g and b\\u000a 1?\\u000a g\\u000a +\\u000a electron states of a O2 molecule are excited by an electrical discharge. The presence of vibrationally excited and electronically excited O2 molecules in the oxygen plasma allows

A. M. Starik; B. I. Lukhovitski?; V. V. Naumov; N. S. Titova

2007-01-01

11

CO 2 capture using oxygen enhanced combustion strategies for natural gas power plants  

Microsoft Academic Search

This paper describes a series of experiments conducted with natural gas in air and in mixtures of oxygen and recycled flue gas, termed O2\\/CO2 recycle combustion. The objective is to enrich the flue gas with CO2 to facilitate its capture and sequestration. Detailed measurements of gas composition, flame temperature and heat flux profiles were taken inside CANMET's 0.3MWth down-fired vertical

Yewen Tan; Mark A. Douglas; Kelly V. Thambimuthu

2002-01-01

12

Pulse Combustion Control Technology for Oxygen Atmosphere  

Microsoft Academic Search

A new combustion control method for oxygen-enriched or pure-oxygen ceramic roller kilns is proposed in this paper. This kind of roller kiln uses high-concentration oxygen or pure oxygen as the combustion-supporting medium. The new method introduces the pulse combustion control technology into the ceramic roller kiln to fine tune its oxygen-and-gas proportional regulator. This technology can greatly improve the combustion

Chen Jing; Huang Bihui; Yuan Youxin; Chun Xiao; Xiang Kui

2009-01-01

13

Characteristics of non-premixed oxygen-enhanced combustion: I. The presence of appreciable oxygen at the location of maximum temperature  

SciTech Connect

The presence of appreciable molecular oxygen at the location of maximum temperature has been observed in non-premixed oxygen-enhanced combustion (OEC) processes, specifically in flames having a high stoichiometric mixture fraction (Z{sub st}) produced with diluted fuel and oxygen-enrichment. For conventional fuel-air flames, key features of the flame are consistent with the flame sheet approximation (FSA). In particular, the depletion of O{sub 2} at the location of maximum temperature predicted by the FSA correlates well with the near-zero O{sub 2} concentration measured at this location for conventional fuel-air flames. In contradistinction, computational analysis with detailed kinetics demonstrates that for OEC flames at high Z{sub st}: (1) there is an appreciable concentration of O{sub 2} at the location of maximum temperature and (2) the maximum temperature is not coincident with the location of global stoichiometry, O{sub 2} depletion, or maximum heat release. We investigate these phenomena computationally in three non-premixed ethylene flames at low, moderate, and high Z{sub st}, but with equivalent adiabatic flame temperatures. Results demonstrate that the location of O{sub 2} depletion occurs in the vicinity of global stoichiometry for flames of any Z{sub st} and that the presence of appreciable O{sub 2} at the location of maximum temperature for high Z{sub st} flames is caused by a shift in the location of maximum temperature relative to the location of O{sub 2} depletion. This shifting is attributed to: (1) finite-rate multi-step chemistry resulting in exothermic heat release that is displaced from the location of O{sub 2} depletion and (2) the relative location of the heat release region with respect to the fuel and oxidizer boundaries in mixture fraction space. A method of superposition involving a variation of the flame sheet approximation with two heat sources is shown to be sufficient in explaining this phenomenon. (author)

Skeen, S.A.; Axelbaum, R.L. [Department of Energy, Environmental, and Chemical Engineering, Washington University in St. Louis, One Brookings Drive, Box 1180, St. Louis, MO 63130 (United States); Yablonsky, G. [Department of Energy, Environmental, and Chemical Engineering, Washington University in St. Louis, One Brookings Drive, Box 1180, St. Louis, MO 63130 (United States); Parks College, Saint Louis University, St. Louis, MO 63103 (United States)

2009-11-15

14

CFD Evaluation of Oxygen Enhanced Combustion: Impacts On NOx Emissions, Carbon-In-Flyash and Waterwall Corrosion  

Microsoft Academic Search

ABSTRACT This paper discusses,the results of a Computational,Fluid Dynamics,(CFD) based evaluation of the impact of oxygenenhanced,combustion,in asubcritical wall-fired pulverized coal (PC) utility boiler. Praxair has previously demonstrated through pilot-scale and full-scale burner testing that significant reductions in NOx emissions can be obtained throughoxygen enhancement,in,low-NOx burners. CFD modeling,conducted,by Reaction Engineering International (REI) has predicted that similar reductions of NOx emissions can

M. Cremer; K. Davis; H. Wang; Z. Chen

15

Dilute Oxygen Combustion - Phase 3 Report  

SciTech Connect

Dilute Oxygen Combustion (DOC) burners have been successfully installed and operated in the reheat furnace at Auburn Steel Co., Inc., Auburn, NY, under Phase 3 of the Dilute Oxygen Combustion project. Two new preheat zones were created employing a total of eight 6.5 MMBtu/hr capacity burners. The preheat zones provide a 30 percent increase in maximum furnace production rate, from 75 tph to 100 tph. The fuel rate is essentially unchanged, with the fuel savings expected from oxy-fuel combustion being offset by higher flue gas temperatures. When allowance is made for the high nitrogen level and high gas phase temperature in the furnace, measured NOx emissions are in line with laboratory data on DOC burners developed in Phase 1 of the project. Burner performance has been good, and there have been no operating or maintenance problems. The DOC system continues to be used as part of Auburn Steel's standard reheat furnace practice. High gas phase temperature is a result of the high firing density needed to achieve high production rates, and little opportunity exists for improvement in that area. However, fuel and NOx performance can be improved by further conversion on furnace zones to DOC burners, which will lower furnace nitrogen levels. Major obstacles are cost and concern about increased formation of oxide scale on the steel. Oxide scale formation may be enhanced by exposure of the steel to higher concentrations of oxidizing gas components (primarily products of combustion) in the higher temperature zones of the furnace. Phase 4 of the DOC project will examine the rate of oxide scale formation in these higher temperature zones and develop countermeasures that will allow DOC burners to be used successfully in these furnace zones.

Riley, Michael F.

2000-05-31

16

Dilute Oxygen Combustion Phase 3 Final Report  

SciTech Connect

Dilute Oxygen Combustion (DOC) burners have been successfully installed and operated in the reheat furnace at Auburn Steel Co., Inc., Auburn, NY, under Phase 3 of the Dilute Oxygen Combustion project. Two new preheat zones were created employing a total of eight 6.5 MMBtu/hr capacity burners. The preheat zones provide a 30 percent increase in maximum furnace production rate, from 75 tph to 100 tph. The fuel rate is essentially unchanged, with the fuel savings expected from oxy-fuel combustion being offset by higher flue gas temperatures. When allowance is made for the high nitrogen level and high gas phase temperature in the furnace, measured NOx emissions are in line with laboratory data on DOC burners developed in Phase 1 of the project. Burner performance has been good and there have been no operating or maintenance problems. The DOC system continues to be used as part of Auburn Steel?s standard reheat furnace practice. High gas phase temperature is a result of the high firing density needed to achieve high production rates, and little opportunity exists for improvement in that area. However, fuel and NOx performance can be improved by further conversion of furnace zones to DOC burners, which will lower furnace nitrogen levels. Major obstacles are cost and concern about increased formation of oxide scale on the steel. Oxide scale formation may be enhanced by exposure of the steel to higher concentrations of oxidizing gas components (primarily products of combustion) in the higher temperature zones of the furnace. Phase 4 of the DOC project will examine the rate of oxide scale formation in these higher temperature zones and develop countermeasures that will allow DOC burners to be used successfully in these furnace zones.

Riley, M.F.; Ryan, H.M.

2000-05-31

17

Catalytically enhanced combustion process  

SciTech Connect

This patent describes a fuel having improved combustion efficiency. It comprises a petroleum based liquid hydrocarbon; and a combustion catalyst comprising from about 18 to about 21 weight percent naphthalene, from about 75 to about 80 weight percent toluene, and from about 2.8 to about 3.2 weight percent benzyl alcohol.

Rodriguez, C.

1992-05-26

18

Infrared Multiphoton Ignition and Enhancement of Combustion; Final Report,  

National Technical Information Service (NTIS)

The research demonstrated the feasibility of obtaining reliable ignition and enhancement of combustion by a novel concept, Infrared Multiphoton Absorption/Dissociation (IRMPA/IRMPD). A methanol-oxygen system was chosen to test this concept because methano...

M. Lavid A. T. Poulos

1986-01-01

19

SITE PROGRAM APPLICATIONS ANALYSIS ASSESSMENT OF SUPERFUND APPLICATIONS FOR THE AMERICAN COMBUSTION INC. PYRETRON OXYGEN ENHANCED BURNER  

EPA Science Inventory

Incineration is widely used to clean up Superfund sites. Modifications which improve the efficiency with which waste can be incinerated are therefore of interest to EPA. Oxygen/air burners are of interest because their installation on conventional incinerators can allow for signi...

20

ENHANCED COMBUSTION WOODSTOVE (ECW) TECHNOLOGY  

EPA Science Inventory

The paper discusses Enhanced Combustion Woodstove (ECW) technology, developed by EPA in response to the field observation that woodstoves certified by EPA as being clean burning were not achieving the level of emission control "seen" in laboratory tests. ts development was also i...

21

Dilute Oxygen Combustion Phase IV Final Report  

SciTech Connect

Novel furnace designs based on Dilute Oxygen Combustion (DOC) technology were developed under subcontract by Techint Technologies, Coraopolis, PA, to fully exploit the energy and environmental capabilities of DOC technology and to provide a competitive offering for new furnace construction opportunities. Capital cost, fuel, oxygen and utility costs, NOx emissions, oxide scaling performance, and maintenance requirements were compared for five DOC-based designs and three conventional air5-fired designs using a 10-year net present value calculation. A furnace direct completely with DOC burners offers low capital cost, low fuel rate, and minimal NOx emissions. However, these benefits do not offset the cost of oxygen and a full DOC-fired furnace is projected to cost $1.30 per ton more to operate than a conventional air-fired furnace. The incremental cost of the improved NOx performance is roughly $6/lb NOx, compared with an estimated $3/lb. NOx for equ8pping a conventional furnace with selective catalytic reduction (SCCR) technology. A furnace fired with DOC burners in the heating zone and ambient temperature (cold) air-fired burners in the soak zone offers low capital cost with less oxygen consumption. However, the improvement in fuel rate is not as great as the full DOC-fired design, and the DOC-cold soak design is also projected to cost $1.30 per ton more to operate than a conventional air-fired furnace. The NOx improvement with the DOC-cold soak design is also not as great as the full DOC fired design, and the incremental cost of the improved NOx performance is nearly $9/lb NOx. These results indicate that a DOC-based furnace design will not be generally competitive with conventional technology for new furnace construction under current market conditions. Fuel prices of $7/MMBtu or oxygen prices of $23/ton are needed to make the DOC furnace economics favorable. Niche applications may exist, particularly where access to capital is limited or floor space limitations are critical. DOC technology will continue to have a highly competitive role in retrofit applications requiring increases in furnace productivity.

Riley, M.F.

2003-04-30

22

The combustion kinetics of coal chars in oxygen-enriched environments.  

SciTech Connect

Oxygen-enhanced and oxygen-fired pulverized coal combustion is actively being investigated to achieve emission reductions and reductions in flue gas cleanup costs, as well as for coal-bed methane and enhanced oil recovery applications. To fully understand the results of pilot scale tests and to accurately predict scale-up performance through CFD modeling, accurate rate expressions are needed to describe coal char combustion under these unconventional combustion conditions. In the work reported here, the combustion rates of two pulverized coal chars have been measured in both conventional and oxygen-enriched atmospheres. A combustion-driven entrained flow reactor equipped with an optical particle-sizing pyrometry diagnostic and a rapid-quench sampling probe has been used for this investigation. Highvale subbituminous coal and a high-volatile eastern United States bituminous coal have been investigated, over oxygen concentrations ranging from 6 to 36 mol% and gas temperatures of 1320-1800 K. The results from these experiments demonstrate that pulverized coal char particles burn under increasing kinetic control in elevated oxygen environments, despite their higher burning rates in these environments. Empirical fits to the data have been successfully performed over the entire range of oxygen concentrations using a single-film oxidation model. Both a simple nth-order Arrhenius expression and an nth-order Langmuir-Hinshelwood kinetic equation provide good fits to the data. Local fits of the nth-order Arrhenius expression to the oxygen-enriched and oxygen-depleted data produce lower residuals in comparison to fits of the entire dataset. These fits demonstrate that the apparent reaction order varies from 0.1 under near-diffusion-limit oxygen-depleted conditions to 0.5 under oxygen-enriched conditions. Burnout predictions show good agreement with measurements. Predicted char particle temperatures tend to be low for combustion in oxygen-depleted environments.

Shaddix, Christopher R.; Murphy, Jeffrey J.

2004-09-01

23

New Findings on Combustion Behavior of Oxygenated Synthetic Diesel Fuels  

Microsoft Academic Search

New results were obtained on pollutants evolution during the combustion of four oxygenated fuels, whichwere compared with n-tetradecane and n-octane combustion. Three different techniques were adopted on a single cylinder direct injection diesel engine, equipped with optical accesses: two-colour pyrometry for the measurement of in-cylinder soot loading, high speed cinematography for the visualization and analysis of spray and combustion, fast

C. BEATRICE; C. BERTOLI; N. D. GIACOMO

1998-01-01

24

DEMONSTRATION BULLETIN: THE PYRETRON OXYGEN BURNER, AMERICAN COMBUSTION TECHNOLOGIES, INC.  

EPA Science Inventory

The Pyretron is a burner which is designed to allow for the injection of oxygen into the combustion air stream for the purpose of increasing the efficiency of a hazardous waste incinerator. The SITE demonstration of the Pyretron took place at the U.S. EPA's Combustion Re...

25

Apparatus for Oxygen-Filled Closed Flask Combustion.  

National Technical Information Service (NTIS)

The container for the oxygen may be an Erlenmeyer flask. Combustible materials are oxidized as one of the steps in a chemical analysis procedure. The sample is ignited by remote control using a lamp which focuses rays on a combustible light absorbing fuse...

C. L. Ogg

1964-01-01

26

Infrared multiphoton ignition and enhancement of combustion. Final report  

SciTech Connect

The research demonstrated the feasibility of obtaining reliable ignition and enhancement of combustion by a novel concept, Infrared Multiphoton Absorption/Dissociation (IRMPA/IRMPD). A methanol-oxygen system was chosen to test this concept because methanol is a potential alternative fuel susceptible to IRMPD. Multiphoton absorption, dissociation, and ignition experiments were conducted in closed pyrex reaction cells with IR-transmitting NaCl windows. Various pressures of pure methanol and methanol-oxygen mixtures were irradiated with single pulses from a TEA CO/sub 2/ laser usually tuned at 10.33 micrometers and focused to fluences in the range 1-80 J/cm2. Temporal and spatial ignition behaviors were investigated and successful ignitions were obtained by multiphoton absorption processes. The research scope was expanded to include a second alcohol, 2-propanol.

Lavid, M.; Poulos, A.T.

1986-08-01

27

Simulation of surface profile formation in oxygen laser cutting of mild steel due to combustion cycles  

Microsoft Academic Search

A physicomathematical model of cyclic iron combustion in an oxygen flow during oxygen laser cutting of metal sheets is developed. The combustion front is set into motion by focused laser radiation and a heterogeneous oxidation reaction in oxygen. The burning rate is limited by oxygen supply from the gas phase towards the metal surface, and the interface motion depends on

G. V. Ermolaev; O. B. Kovalev

2009-01-01

28

Combustion of coal chars in oxygen-enriched atmospheres  

SciTech Connect

This work pertains to the high-temperature combustion of pulverized coal chars under oxygen-enriched atmospheres. Single char particles were burned in a drop-tube furnace, electrically-heated to 1300-1500 K, in 21%, 50% and 100% O{sub 2}, in a balance of N{sub 2}. Their luminous combustion histories were observed with two-color ratio pyrometry. A solution of the Planckian ratio-pyrometry equation for temperature was implemented, extending on Wien's approximation. The temperature and time histories for 45-53 {mu}m bituminous chars experienced wide particle-to-particle disparity, and varied depending on oxygen mole fraction and furnace temperature. Average char surface temperatures increased from 1600-1800 K in air, to 2100-2300 K in 50% O-2, to 2300-2400 K in 100% O{sub 2}, at gas temperatures of 1300-1500 K, respectively. Combustion durations decreased from 25-45 ms in air, to 8-17 ms in 50% O{sub 2}, to 6-13 in 100% O{sub 2}. Thus, average particle temperatures increased by up to 45%, whereas burnout times decreased by up to 87% as combustion was progressively enriched in O{sub 2} until 100% was attained. The apparent and intrinsic reactivity of the chars burning at 1500 K gas temperature were found to increase by factors of to 8 and 35, respectively, as the oxygen mole fraction increased by a factor of five, from 21% to 100%.

Bejarano, P.A.; Levendis, Y.A. [Northeastern University, Boston, MA (United States)

2007-07-01

29

The relationship between oxygen consumption rate and temperature during coal spontaneous combustion  

Microsoft Academic Search

Spontaneous combustion is a major natural disaster in coal production. In the process of exploring coal self-ignition, a series of hypotheses have been put forward, most scholars agree that the current coal-oxygen compound theory. Oxygen consumption rate reflects the status of coal spontaneous combustion, and it is also one of the parameters necessary for numerical simulation of coal spontaneous combustion.

Jianfang Zhu; Ning He; Dengji Li

30

Modeling the effects of late cycle oxygen enrichment on diesel engine combustion and emissions.  

SciTech Connect

A multidimensional simulation of Auxiliary Gas Injection (AGI) for late cycle oxygen enrichment was exercised to assess the merits of AGI for reducing the emissions of soot from heavy duty diesel engines while not adversely affecting the NO{sub x} emissions of the engine. Here, AGI is the controlled enhancement of mixing within the diesel engine combustion chamber by high speed jets of air or another gas. The engine simulated was a Caterpillar 3401 engine. For a particular operating condition of this engine, the simulated soot emissions of the engine were reduced by 80% while not significantly affecting the engine-out NO{sub x} emissions compared to the engine operating without AGI. The effects of AGI duration, timing, and orientation are studied to confirm the window of opportunity for realizing lower engine-out soot while not increasing engine out NO{sub x} through controlled enhancement of in-cylinder mixing. These studies have shown that this window occurs during the late combustion cycle, from 20 to 60 crank angle degrees after top-dead-center. During this time, the combustion chamber temperatures are sufficiently high that soot oxidation increases in response in increased mixing, but the temperature is low enough that NO{sub x} reactions are quenched. The effect of the oxygen composition of the injected air is studied for the range of compositions between 21% and 30% oxygen by volume. This is the range of oxygen enrichment that is practical to produce from an air separation membrane. Simulations showed that this level of oxygen enrichment is insufficient to provide an additional benefit by either increasing the level of soot oxidation or prolonging the window of opportunity for increasing soot oxidation through enhanced mixing.

Mather, D. K.; Foster, D. E.; Poola, R. B.; Longman, D. E.; Chanda, A.; Vachon, T. J.

2002-02-28

31

Studies of MHD generator performance with oxygen enriched coal combustion  

NASA Astrophysics Data System (ADS)

This paper presents calculations made using the Aerodyne PACKAGE (Plasma Analysis, Chemical Kinetics, and Generator Efficiency) computer code which bear on two questions which arise in connection with choices between oxygen enrichment and air preheating to attain the high combustion temperatures needed for open-cycle, coal-fired MHD power generation. The first question is which method produces the highest enthalpy extraction per unit channel length. The second is, in test facilities intended to study tradeoffs between oxygen enrichment and preheated air, can good generator performance be obtained from the same physical channel for different combustor compositions. The answer to the first question is found to depend on what combustor conditions are taken to be comparable. As for the second question, it is found that operation with channel input from off-design combustor conditions can cause serious problems, which can be partially alleviated by changing the channel load factors.

Wormhoudt, J.; Yousefian, V.; Kolb, C. E.; Martinez-Sanchez, M.

1980-07-01

32

Enhanced Combustion Low NOx Pulverized Coal Burner  

SciTech Connect

For more than two decades, Alstom Power Inc. (Alstom) has developed a range of low cost, infurnace technologies for NOx emissions control for the domestic U.S. pulverized coal fired boiler market. This includes Alstom's internally developed TFS 2000{trademark} firing system, and various enhancements to it developed in concert with the U.S. Department of Energy. As of the date of this report, more than 270 units representing approximately 80,000 MWe of domestic coal fired capacity have been retrofit with Alstom low NOx technology. Best of class emissions range from 0.18 lb/MMBtu for bituminous coal to 0.10 lb/MMBtu for subbituminous coal, with typical levels at 0.24 lb/MMBtu and 0.13 lb/MMBtu, respectively. Despite these gains, NOx emissions limits in the U.S. continue to ratchet down for new and existing boiler equipment. On March 10, 2005, the Environmental Protection Agency (EPA) announced the Clean Air Interstate Rule (CAIR). CAIR requires 25 Eastern states to reduce NOx emissions from the power generation sector by 1.7 million tons in 2009 and 2.0 million tons by 2015. Low cost solutions to meet such regulations, and in particular those that can avoid the need for a costly selective catalytic reduction system (SCR), provide a strong incentive to continue to improve low NOx firing system technology to meet current and anticipated NOx control regulations. The overall objective of the work is to develop an enhanced combustion, low NOx pulverized coal burner, which, when integrated with Alstom's state-of-the-art, globally air staged low NOx firing systems will provide a means to achieve: Less than 0.15 lb/MMBtu NOx emissions when firing a high volatile Eastern or Western bituminous coal, Less than 0.10 lb/MMBtu NOx emissions when firing a subbituminous coal, NOx reduction costs at least 25% lower than the costs of an SCR, Validation of the NOx control technology developed through large (15 MWt) pilot scale demonstration, and Documentation required for economic evaluation and commercial application. During the project performance period, Alstom performed computational fluid dynamics (CFD) modeling and large pilot scale combustion testing in its Industrial Scale Burner Facility (ISBF) at its U.S. Power Plant Laboratories facility in Windsor, Connecticut in support of these objectives. The NOx reduction approach was to optimize near-field combustion to ensure that minimum NOx emissions are achieved with minimal impact on unburned carbon in ash, slagging and fouling, corrosion, and flame stability/turn-down. Several iterations of CFD and combustion testing on a Midwest coal led to an optimized design, which was extensively combustion tested on a range of coals. The data from these tests were then used to validate system costs and benefits versus SCR. Three coals were evaluated during the bench-scale and large pilot-scale testing tasks. The three coals ranged from a very reactive subbituminous coal to a moderately reactive Western bituminous coal to a much less reactive Midwest bituminous coal. Bench-scale testing was comprised of standard ASTM properties evaluation, plus more detailed characterization of fuel properties through drop tube furnace testing and thermogravimetric analysis. Bench-scale characterization of the three test coals showed that both NOx emissions and combustion performance are a strong function of coal properties. The more reactive coals evolved more of their fuel bound nitrogen in the substoichiometric main burner zone than less reactive coal, resulting in the potential for lower NOx emissions. From a combustion point of view, the more reactive coals also showed lower carbon in ash and CO values than the less reactive coal at any given main burner zone stoichiometry. According to bench-scale results, the subbituminous coal was found to be the most amenable to both low NOx, and acceptably low combustibles in the flue gas, in an air staged low NOx system. The Midwest bituminous coal, by contrast, was predicted to be the most challenging of the three coals, with the Western bituminous coal predicted to beh

David Towle; Richard Donais; Todd Hellewell; Robert Lewis; Robert Schrecengost

2007-06-30

33

Alarming Oxygen Depletion Caused by Hydrogen Combustion and Fuel Cells and their Resolution by Magnegas$^{TM}$  

Microsoft Academic Search

We recall that hydrogen combustion does resolve the environmental problems of fossil fuels due to excessive emission of carcinogenic substances and carbon dioxide. However, hydrogen combustion implies the permanent removal from our atmosphere of directly usable oxygen, a serious environmental problem called oxygen depletion, since the combustion turns oxygen into water whose separation to restore the original oxygen is prohibitive

R. M. Santilli

2000-01-01

34

Modeling of laser-induced combustion of iron in oxygen during gas-laser cutting  

Microsoft Academic Search

A physical and mathematical model is proposed for cyclic combustion of iron in an oxygen stream during oxygen gas-laser cutting\\u000a of sheet metal. The combustion front is driven by focused laser radiation and heterogeneous iron oxidation in oxygen. The\\u000a burning rate is limited by the rate of oxygen supply from the gas phase to the metal surface, and the motion

G. V. Ermolaev; O. B. Kovalev

2010-01-01

35

Determination of total fluorine in coal by use of oxygen flask combustion method with catalyst  

Microsoft Academic Search

A rapid and convenient analytical method has been developed for the determination of total F in coal by use of oxygen flask combustion (OFC) method with catalyst. Coal was combusted with excessive oxygen in a quartz flask and the resulting gas was absorbed in water, and the fluoride ion in the solution was determined with a fluoride-ion selective electrode (F-ISE).

Wenhua Geng; Tsunenori Nakajima; Hirokazu Takanashi; Akira Ohki

2007-01-01

36

Ignition and Kinetics Analysis of Coal Combustion in Low Oxygen Concentration  

Microsoft Academic Search

The combustion of coals in low oxygen concentration, which exists widely in industry combustion, was investigated by the use of thermogravimetry. Experimental results show that thermogravity\\/differential thermogravity\\/differential scanning calorimetry curves of four studied coals shift to a higher temperature zone in lower oxygen concentration. The ignition temperature is almost constant for each coal and increases with the increased coal rank.

Y. Liu; C. Wang; D. Che

2012-01-01

37

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

38

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

39

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

40

Biologically Enhanced Oxygen Transfer in the Activated Sludge Process.  

National Technical Information Service (NTIS)

Biologically enhanced oxygen transfer has been a hypothesis to explain observed oxygen transfer rates in activated sludge systems that were well above that predicted from aerator clean-water testing. The enhanced oxygen transfer rates were based on tests ...

J. S. Mueller H. D. Stensel R. C. Brenner

1990-01-01

41

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

42

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

43

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

44

Combustion characteristics of a swirling inverse diffusion flame upon oxygen content variation  

Microsoft Academic Search

The combustion characteristics of a swirling inverse diffusion flame (IDF) upon variation of the oxygen content in the oxidizer were experimentally studied. The oxidizer jet was a mixture mainly composed of oxygen and nitrogen gases, with a volumetric oxygen fraction of 20%, 21% and 26%, and liquefied petroleum gas (LPG) was used as the fuel. Each set of experiment was

H. S. Zhen; C. W. Leung; C. S. Cheung

2011-01-01

45

A zero emission combustion power plant for enhanced oil recovery  

Microsoft Academic Search

We have studied an internal combustion CO2 power plant to enhanced oil recovery. The plant has air separation of O2 for combustion and of N2 for injection, a combution chamber, a turbine, a compressors, a recuperator, and a cooling tower. The oil-derived gases are used to produce liquid CO2, highly compressed N2, process steam and, if necessary, power. No exhaust

Göran Wall; Eugene I. Yantovskii; Lars Lindquist; Joakim Tryggstad

1995-01-01

46

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

47

Development of an Internal-Combustion Engine Fueled with Cryogenic Hydrogen and Oxygen.  

National Technical Information Service (NTIS)

The practicability of utilizing a hydrogen-oxygen-fueled, internal-combustion engine in conjunction with low-pressure cryogenic tanks was determined through an experimental investigation conducted at the Air Force Aero Propulsion Laboratory. This experime...

R. E. Quigley

1967-01-01

48

Plasma enhancement of combustion of solid fuels  

SciTech Connect

Plasma fuel systems that increase the coal burning efficiency are discussed. The systems were tested for fuel oil-free startup of boilers and stabilizating a pulverized-coal flame in power-generating boilers equipped with different types of burner and burning all types of power-generating coal. Plasma ignition, thermochemical treatment of an air-fuel mixture prior to combustion, and its burning in a power-generating boiler were numerically simulated. Environmental friendliness of the plasma technology was demonstrated.

Askarova, A.S.; Karpenko, E.I.; Messerle, V.E.; Ustimenko, A.B. [Institute of Combustion Problems, Alma Ata (Kazakhstan)

2006-03-15

49

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

50

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

51

A hybrid process combining oxygen enriched air combustion and membrane separation for post-combustion carbon dioxide capture  

Microsoft Academic Search

For carbon dioxide capture and storage (CCS), similar to a large majority of industrial processes, the separation (i.e. capture) step dominates the costs of the technological chain. Based on a concept of minimal work of concentration, the evaluation of a tentative capture framework which combines an oxygen enrichment step before combustion and a CO2 capture step from flue gas has

Eric Favre; Roda Bounaceur; Denis Roizard

2009-01-01

52

Enhancement of pulverized coal combustion by plasma technology  

SciTech Connect

Plasma-assisted pulverized coal combustion is a promising technology for thermal power plants (TPP). This article reports one- and three- dimensional numerical simulations, as well as laboratory and industrial measurements of coal combustion using a plasma-fuel system (PFS). The chemical kinetic and fluid mechanics involved in this technology are analysed. The results show that a PFS, can be used to promote early ignition and enhanced stabilization of a pulverized coal flame. It is shown that this technology, in addition to enhancing the combustion efficiency of the flame, reduces harmful emissions from power coals of all ranks (brown, bituminous, anthracite and their mixtures). Data summarising the experience of 27 pulverized coal boilers in 16 thermal power plants in several countries (Russia, Kazakhstan, Korea, Ukraine, Slovakia, Mongolia and China), embracing steam productivities from 75 to 670 tons per hour (TPH), are presented. Finally, the practical computation of the characteristics of the PFS, as function of coal properties, is discussed.

Gorokhovski, M.A.; Jankoski, Z.; Lockwood, F.C.; Karpenko, E.I.; Messerle, V.E.; Ustimenko, A.B. [University of Rouen, Rouen (France)

2007-07-01

53

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

54

Pulse Combustion: Impinging Jet Heat Transfer Enhancement  

Microsoft Academic Search

A new method for convective heat transfer enhancement is described. The technique involves the use of a pulse combustor to generate a transient jet that impinges on a flat plate. Enhancements in convective heat transfer of a factor of up to 2.5, compared to a steady impinging jet at approximately the same Reynolds number, have been obtained. Heat transfer data

R A. EIBECK; J. O. KELLER; T. T. BRAMLETTE; D. J. SAILOR

1993-01-01

55

Sonically Enhanced Combustion of Coal Water Slurry Fuel.  

NASA Astrophysics Data System (ADS)

An investigation was performed to demonstrate that a high intensity acoustic field can enhance the convective transfer processes occurring during CWSF (coal water slurry fuel) combustion. It was carried out in a 300,000 Btu/h sonic combustor. For the runs conducted, SPLs of 156 dB and 145 dB, respectively, were measured below the fuel injection point and before the exit to the combustor. Frequency was held at 1400 Hz. Combustion efficiency was improved when the extent of burnout was well below 100% and when the droplet size distribution was relatively coarse. The maximum improvement in burnout was 7.9%, under the coarsest atomization conditions investigated. Results from modelling show that sonically enhanced heat transfer plays a negligible role in improving the rate of combustion of CWSF. However, such enhancement may well be important for other applications (e.g. spray drying) involving longer drying times and/or small steady slip velocities. The application of a sonic field improves the rate of combustion of CWSF mainly through increased mass transfer rates, the enhancement being greatest for relatively coarse atomization. It is commonly accepted that the largest particles of fuel are the most likely to avoid full burnout in a practical combustor and thus contribute to erosion, slagging, and fouling via inertial mechanisms. By acting preferentially on these particles, operational difficulties can be minimized.

Ramachandran, Prakash

1990-01-01

56

Sonically enhanced combustion of coal water slurry fuel  

SciTech Connect

An investigation was performed to demonstrate that a high intensity acoustic field can enhance the convective transfer processes occurring during CWSF (coal water slurry fuel) combustion. It was carried out in a 300,000 Btu/h sonic combustor. For the runs conducted, SPLs of 156 dB and 145 dB, respectively, were measured below the fuel injection point and before the exit to the combustor. Frequency was held at 1,400 Hz. Combustion efficiency was improved when the extent of burnout was well below 100% and when the droplet size distribution was relatively coarse. The maximum improvement in burnout was 7.9%, under the coarsest atomization conditions investigated. Results from modelling show that sonically enhanced heat transfer plays a negligible role in improving the rate of combustion of CWSF. However, such enhancement may well be important for other applications (e.g. spray drying) involving longer drying times and/or small steady slip velocities. The application of a sonic field improves the rate of combustion of CWSF mainly through increased mass transfer rates, the enhancement being greatest for relatively coarse atomization. It is commonly accepted that the largest particles of fuel are the most likely to avoid full burnout in a practical combustor and thus contribute to erosion, slagging, and fouling via inertial mechanisms. By acting preferentially on these particles, operational difficulties can be minimized.

Ramachandran, P.

1990-01-01

57

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

58

Methanol Droplet Combustion in Oxygen-Inert Environments in Microgravity.  

National Technical Information Service (NTIS)

The Flame Extinguishment (FLEX) experiment that is currently underway in the Combustion Integrated Rack facility onboard the International Space Station is aimed at understanding the effects of inert diluents on the flammability of condensed phase fuels. ...

D. L. Dietrich F. A. Williams M. C. Hicks V. Nayagam

2013-01-01

59

Simulation of surface profile formation in oxygen laser cutting of mild steel due to combustion cycles  

NASA Astrophysics Data System (ADS)

A physicomathematical model of cyclic iron combustion in an oxygen flow during oxygen laser cutting of metal sheets is developed. The combustion front is set into motion by focused laser radiation and a heterogeneous oxidation reaction in oxygen. The burning rate is limited by oxygen supply from the gas phase towards the metal surface, and the interface motion depends on the local temperature. A 3D numerical simulation predicts wavy structures on the metal surface; their linear sizes depend on the scanning speed of the laser beam, the thickness of the produced liquid oxide film and the parameters of the oxygen jet flow. Simulation results help in understanding the mechanism of striation formation during oxygen gas-laser cutting of mild steel and are in qualitative agreement with experimental findings.

Ermolaev, G. V.; Kovalev, O. B.

2009-09-01

60

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

61

Alarming Oxygen Depletion Caused by Hydrogen Combustion and Fuel Cells and their Resolution by Magnegas$^{TM}$  

Microsoft Academic Search

We recall that hydrogen combustion does resolve the environmental problems of\\u000afossil fuels due to excessive emission of carcinogenic substances and carbon\\u000adioxide. However, hydrogen combustion implies the permanent removal from our\\u000aatmosphere of directly usable oxygen, a serious environmental problem called\\u000aoxygen depletion, since the combustion turns oxygen into water whose separation\\u000ato restore the original oxygen is prohibitive

Ruggero Maria Santilli

2000-01-01

62

Reactive oxygen species enhance insulin sensitivity  

PubMed Central

SUMMARY Chronic reactive oxygen species (ROS) production by mitochondria may contribute to the development of insulin resistance, a primary feature of type 2 diabetes. In recent years it has become apparent that ROS generation in response to physiological stimuli such as insulin may also facilitate signaling by reversibly oxidizing and inhibiting protein tyrosine phosphatases (PTPs). Here we report that mice lacking one of the key enzymes involved in the elimination of physiological ROS, glutathione peroxidase 1 (Gpx1), were protected from high fat diet-induced insulin resistance. The increased insulin sensitivity in Gpx1?/? mice was attributed to insulin-induced phosphatidylinositol-3-kinase/Akt signaling and glucose uptake in muscle and could be reversed by the anti-oxidant N-acetylcysteine. Increased insulin signaling correlated with enhanced oxidation of the PTP family member PTEN, which terminates signals generated by phosphatidylinositol-3-kinase. These studies provide causal evidence for the enhancement of insulin signaling by ROS in vivo.

Loh, Kim; Deng, Haiyang; Fukushima, Atsushi; Cai, Xiaochu; Boivin, Benoit; Galic, Sandra; Bruce, Clinton; Shields, Benjamin J.; Skiba, Beata; Ooms, Lisa M.; Stepto, Nigel; Wu, Ben; Mitchell, Christina A.; Tonks, Nicholas K.; Watt, Matthew J.; Febbraio, Mark A.; Crack, Peter J.; Andrikopoulos, Sofianos; Tiganis, Tony

2010-01-01

63

Reactive oxygen species enhance insulin sensitivity.  

PubMed

Chronic reactive oxygen species (ROS) production by mitochondria may contribute to the development of insulin resistance, a primary feature of type 2 diabetes. In recent years it has become apparent that ROS generation in response to physiological stimuli such as insulin may also facilitate signaling by reversibly oxidizing and inhibiting protein tyrosine phosphatases (PTPs). Here we report that mice lacking one of the key enzymes involved in the elimination of physiological ROS, glutathione peroxidase 1 (Gpx1), were protected from high-fat-diet-induced insulin resistance. The increased insulin sensitivity in Gpx1(-/-) mice was attributed to insulin-induced phosphatidylinositol-3-kinase/Akt signaling and glucose uptake in muscle and could be reversed by the antioxidant N-acetylcysteine. Increased insulin signaling correlated with enhanced oxidation of the PTP family member PTEN, which terminates signals generated by phosphatidylinositol-3-kinase. These studies provide causal evidence for the enhancement of insulin signaling by ROS in vivo. PMID:19808019

Loh, Kim; Deng, Haiyang; Fukushima, Atsushi; Cai, Xiaochu; Boivin, Benoit; Galic, Sandra; Bruce, Clinton; Shields, Benjamin J; Skiba, Beata; Ooms, Lisa M; Stepto, Nigel; Wu, Ben; Mitchell, Christina A; Tonks, Nicholas K; Watt, Matthew J; Febbraio, Mark A; Crack, Peter J; Andrikopoulos, Sofianos; Tiganis, Tony

2009-10-01

64

Oxygen delivery enhancers: past, present, and future.  

PubMed

In endurance sport the delivery of oxygen to muscles plays a critical role. Indeed, muscle performance declines during prolonged and intense activity as a consequence of the shift from the aerobic to the anaerobic metabolism with an increase of lactate. To enhance the aerobic capacity 2 alternatives may be used: increasing either the transport or the delivery of oxygen. In this setting, blood doping is the practice of illicitly using a drug or blood product to improve athletic performance. Based on this definition, blood doping techniques may include: 1) blood transfusion (autologous or omologous); 2) erythropoiesis-stimulating substances [recombinant human erythropoietin (alpha, beta, omega), darbepoietin-alpha, continuous erythropoiesis receptor activator, hematide]; 3) blood substitutes (hemoglobin-based oxygen carriers, perfluorocarbon emulsions); 4) allosteric modulators of hemoglobin (RSR-13 and RSR-4); 5) gene doping (human erythropoietin gene transfection); 6) gene regulation (hypoxia-inducible transcription factors pathway). In the present overview we will briefly describe the above-mentioned techniques with the aim of underlining potential hematological alternatives to gene doping for increasing aerobic capacity in sport. PMID:18362513

Borrione, P; Mastrone, A; Salvo, R A; Spaccamiglio, A; Grasso, L; Angeli, A

2008-02-01

65

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

66

An experimental study on high temperature and low oxygen air combustion  

NASA Astrophysics Data System (ADS)

High temperature preheated and diluted air combustion has been confirmed as the technology, mainly applied to industrial furnaces and kilns, to realize higher thermal efficiency and lower emissions. The purpose of this study was to investigate fundamental aspects of the above-mentioned combustion experimentally and to compare with those in ordinary hydrocarbon combustion with room temperature air. The test items were exhaust gas components of CO, NOx, flame shape and radical components of CH, OH and C2, which were measured with gas analyser, camera and ICCD(Intensified Charged - Coupled Device) camera. Many phenomena as results appeared in combustion with the oxidizer, low oxygen concentration and extremely high temperature air, such as expansion of the flammable limits, increased flame propagation speed, it looked so strange as compared with those in existing combustion technology. We confirmed that such extraordinary phenomena were believable through the hot-test experiment.

Kim, W. B.; Chung, D. H.; Yang, J. B.; Noh, D. S.

2000-06-01

67

Sonically Enhanced Combustion of Coal Water Slurry Fuel  

Microsoft Academic Search

An investigation was performed to demonstrate that a high intensity acoustic field can enhance the convective transfer processes occurring during CWSF (coal water slurry fuel) combustion. It was carried out in a 300,000 Btu\\/h sonic combustor. For the runs conducted, SPLs of 156 dB and 145 dB, respectively, were measured below the fuel injection point and before the exit to

Prakash Ramachandran

1990-01-01

68

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

69

Reduced Gravity Combustion of Propanol Droplets in Oxygen-Inert Environments  

Microsoft Academic Search

Reduced gravity combustion experiments were performed with individual fiber-supported propanol droplets that were initially about 1 mm in diameter. The environment was composed of an oxygen-inert mixture. Helium, argon, xenon, nitrogen, and carbon dioxide were used as inerts, the oxygen mole fraction was 0.21, and the pressure was 0.03, 0.1, or 0.3 MPa. Use of helium caused extinction at 0.03 MPa and 0.1 MPa,

J. B. Wei; B. D. Shaw

2009-01-01

70

OXYGEN-ENRICHED COAL COMBUSTION WITH CARBON DIOXIDE RECYCLE AND RECOVERY: SIMULATION AND EXPERIMENTAL STUDY  

SciTech Connect

This report examines coal combustion using oxygen feed with carbon dioxide recycle to control the adiabatic flame temperature. Computer simulations using an existing state-of-the-art 3-dimensional computer code for turbulent reacting flows with reacting particles were employed to study the effects of increased carbon dioxide mole fraction on the char burnout, radiant heat transfer, metal partitioning, and NOx formation.

John M. Veranth; Gautham Krishnamoorthy

2001-04-01

71

Influence of Fuel Combustion Gases on the Oxygen Levels in City Atmosphere  

Microsoft Academic Search

Air, which is the material that composes the atmosphere, is a mixture of invisible gases. The atmospheric air consists of approximately 78% nitrogen and 21% oxygen. The remainder is made up of argon, carbon dioxide, several other gases, and water vapor. The combustion of fossil fuels is the greatest source of atmospheric pollution. A convenient way to develop quantitative theory

A. Demirbas

2008-01-01

72

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

73

FIELD DEMONSTRATION OF THE LINDE OXYGEN COMBUSTION SYSTEM ON THE EPA MOBILE INCINERATOR  

EPA Science Inventory

This paper summarizes the various system performance tests and the long-term operating experience of the LINDE Oxygen Combustion System installed on the U.S. Environmental Protection Agency's Mobile Incineration System (MIS) when it was in operation at the Denney Farm site in sou...

74

CO2 Recovery via Coal Combustion in Mixtures of Oxygen and Recycled Flue Gas  

Microsoft Academic Search

The combustion of coal in oxygen with recycled flue gases has been proposed as a means of recovering carbon dioxide during power generation in existing boilers. The feasibility of this process has been evaluated in a pilot scale test furnace and by the use or a boiler performance model to assess the impact on the performance of a 50MWe lignite

R. PAYNE; S. L. Chen; A. M. WOLSKY; W. F. RICHTER

1989-01-01

75

Acoustically enhanced combustion of micronized coal water slurry fuel  

SciTech Connect

A multi-faceted investigation has been carried out to demonstrate analytically and experimentally, that a high intensity acoustic field can be substantially enhance the convective transfer processes occurring during MCWSF (micronized coal water slurry fuel) combustion. The initial stage of the investigation dealt with elucidating the transient as well as time-averaged efforts of high intensity acoustic fields on the heat and mass transfer between a single spherical particle and its environment. A two-dimensional unsteady computer code was developed, which employs the unsteady conservation of mass, momentum, and energy equations for laminar flow in spherical coordinates. One objective of the present project was the modeling of MCWSF combustion in a laboratory scale combustor with and without the application of a sonic field. The influence of various operating parameters (sound frequency and level, etc.) on sonic enhancement could thus be studied. The combustion of pulverized coal (PC) was also modeled for the sake of comparison. The first of the two coal combustion experiments was performed using a flat flame methane-air burner. Micronized coal was injected in the same direction as, and burned together with the methane. The final investigation was carried out in a 300,000 Btu/h sonic combustor. For the runs conducted, SPLs of 156 dB and 145 dB, respectively, were measured below the fuel injection point and before the exit to the combustor. Frequency was held at 1400 Hz. Finally, an attempt was made to model the runs performed in the down-fired unit, using the PCGC-2 code. 61 refs., 60 figs., 8 tabs.

Koopmann, G.M.; Scaroni, A.W.; Yavuzkurt, S.; Reethof, G.; Ramachandran, P.; Ha, M.Y.

1989-05-01

76

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

77

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

78

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

79

Carbon dioxide remediation via oxygen-enriched combustion using dense ceramic membranes  

DOEpatents

A method of combusting pulverized coal by mixing the pulverized coal and an oxidant gas to provide a pulverized coal-oxidant gas mixture and contacting the pulverized coal-oxidant gas mixture with a flame sufficiently hot to combust the mixture. An oxygen-containing gas is passed in contact with a dense ceramic membrane of metal oxide material having electron conductivity and oxygen ion conductivity that is gas-impervious until the oxygen concentration on one side of the membrane is not less than about 30% by volume. An oxidant gas with an oxygen concentration of not less than about 30% by volume and a CO.sub.2 concentration of not less than about 30% by volume and pulverized coal is contacted with a flame sufficiently hot to combust the mixture to produce heat and a flue gas. One dense ceramic membrane disclosed is selected from the group consisting of materials having formulae SrCo.sub.0.8 Fe.sub.0.2 O.sub.x, SrCo.sub.0.5 FeO.sub.x and La.sub.0.2 Sr.sub.0.8 Co.sub.0.4 Fe.sub.0.6 O.sub.x.

Balachandran, Uthamalingam (Hinsdale, IL); Bose, Arun C. (Pittsburgh, PA); McIlvried, Howard G. (Pittsburgh, PA)

2001-01-01

80

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

81

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

82

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

83

COâ emission abatement in IGCC power plants by semiclosed cycles: Part A -- With oxygen-blown combustion  

Microsoft Academic Search

This paper analyzes the fundamentals of IGCC power plants where carbon dioxide produced by syngas combustion can be removed, liquefied and eventually disposed, to limit the environmental problems due to the greenhouse effect. To achieve this goal, a semiclosed-loop gas turbine cycle using an highly-enriched COâ mixture as working fluid was adopted. As the oxidizer, the syngas combustion utilizes oxygen

P. Chiesa; G. Lozza

1999-01-01

84

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

85

Functionalized graphene sheet colloids for enhanced fuel/propellant combustion.  

PubMed

We have compared the combustion of the monopropellant nitromethane with that of nitromethane containing colloidal particles of functionalized graphene sheets or metal hydroxides. The linear steady-state burning rates of the monopropellant and colloidal suspensions were determined at room temperature, under a range of pressures (3.35-14.4 MPa) using argon as a pressurizing fluid. The ignition temperatures were lowered and burning rates increased for the colloidal suspensions compared to those of the liquid monopropellant alone, with the graphene sheet suspension having significantly greater burning rates (i.e., greater than 175%). The relative change in burning rate from neat nitromethane increased with increasing concentrations of fuel additives and decreased with increasing pressure until at high pressures no enhancement was found. PMID:19925013

Sabourin, Justin L; Dabbs, Daniel M; Yetter, Richard A; Dryer, Frederick L; Aksay, Ilhan A

2009-12-22

86

Numerical investigation of mixing and combustion enhancement in supersonic combustors by strut induced streamwise vorticity  

Microsoft Academic Search

A numerical study of mixing and combustion enhancement has been performed for a Mach 2 model scramjet (supersonic combustion ramjet) combustor. Fuel (hydrogen) is injected at supersonic speed through the rear of a lobed strut located at the channel symmetry axis. The shape of the strut is chosen in a way to produce strong streamwise vorticity and thus to enhance

Peter Gerlinger; Peter Stoll; Markus Kindler; Fernando Schneider; Manfred Aigner

2008-01-01

87

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

88

Emission of Oxygenated Polycyclic Aromatic Hydrocarbons from Indoor Solid Fuel Combustion  

PubMed Central

Indoor solid fuel combustion is a dominant source of polycyclic aromatic hydrocarbons (PAHs) and oxygenated PAHs (OPAHs) and the latter are believed to be more toxic than the former. However, there is limited quantitative information on the emissions of OPAHs from solid fuel combustion. In this study, emission factors of OPAHs (EFOPAH) for nine commonly used crop residues and five coals burnt in typical residential stoves widely used in rural China were measured under simulated kitchen conditions. The total EFOPAH ranged from 2.8±0.2 to 8.1±2.2 mg/kg for tested crop residues and from 0.043 to 71 mg/kg for various coals and 9-fluorenone was the most abundant specie. The EFOPAH for indoor crop residue burning were 1~2 orders of magnitude higher than those from open burning, and they were affected by fuel properties and combustion conditions, like moisture and combustion efficiency. For both crop residues and coals, significantly positive correlations were found between EFs for the individual OPAHs and the parent PAHs. An oxygenation rate, Ro, was defined as the ratio of the EFs between the oxygenated and parent PAH species to describe the formation potential of OPAHs. For the studied OPAH/PAH pairs, mean Ro values were 0.16 ~ 0.89 for crop residues and 0.03 ~ 0.25 for coals. Ro for crop residues burned in the cooking stove were much higher than those for open burning and much lower than those in ambient air, indicating the influence of secondary formation of OPAH and loss of PAHs. In comparison with parent PAHs, OPAHs showed a higher tendency to be associated with particulate matter (PM), especially fine PM, and the dominate size ranges were 0.7 ~ 2.1 µm for crop residues and high caking coals and < 0.7 µm for the tested low caking briquettes.

Shen, Guofeng; Tao, Shu; Wang, Wei; Yang, Yifeng; Ding, Junnan; Xue, Miao; Min, Yujia; Zhu, Chen; Shen, Huizhong; Li, Wei; Wang, Bin; Wang, Rong; Wang, Wentao; Wang, Xilong; Russell, Armistead G.

2011-01-01

89

Application of Oxygen Enriched Combustion Air in Radiant Tubes: Feasibility Study. Final Report April 1984-March 1985.  

National Technical Information Service (NTIS)

The objective of the program is to determine the effect of applying oxygen enriched combustion air to radiant tubes. Specifically, the increases in heat transfer rates and thermal efficiency are to be quantified as a function of the oxygen concentration i...

S. R. Huebner R. A. Schmall C. A. Hersch

1985-01-01

90

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

91

Enhanced Combustion Woodstove (ECW) technology. Report for January 1991-July 1993  

SciTech Connect

The paper discusses Enhanced Combustion Woodstove (ECW) technology, developed by EPA in response to the field observation that woodstoves certified by EPA as being clean burning were not achieving the level of emission control 'seen' in laboratory tests. ECW technology is based on the fact that woodstove emissions are caused by the incomplete combustion and pyrolysis of wood in the primary combustion zone. To achieve low emissions, the stove must incorporate a secondary combustion zone above the wood which will hold flame at all times. Current noncatalytic woodstoves can achieve satisfactory secondary combustion only under fairly ideal conditions. Stable secondary combustion may not be achieved at typical low-fire conditions, leading to high emissions. Initial work focused on using an electrical glowplug (ECW electric) to ignite and add energy to the secondary combustion zone. Later work has focused on using a gaseous fuel (ECW gaseous or ECWG) for this purpose.

McCrillis, R.C.; Abbott, J.H.; Ponder, W.H.; Butts, N.L.; Henry, D.S.

1994-01-01

92

BALANCE BETWEEN VASOCONSTRICTION AND ENHANCED OXYGEN DELIVERY  

PubMed Central

Background Hemoglobin (Hb) solutions are potential alternatives to blood transfusion when native oxygen (O2) carrying capacity is lacking. Polymerized bovine Hb (PBH) solutions are characterized by its vasoactivity, low O2 affinity, oncotic effect, prolonged shelf life and stability. Responses to facilitated O2 transport, after exchange transfusion with PBH, were studied in the hamster window chamber model during acute extreme anemia to determine how PBH affects microvascular perfusion and tissue oxygenation. Study Design and Methods An anemic state was induced by hemodilution with a plasma expander (dextran 70 kDa). After hemodilution animals were randomly assigned to exchange transfusion groups based on the concentration of PBH used, namely: PBH at 13gHb/dl [PBH13], PBH diluted to 8 or 4 gHb/dl in albumin solution at matching colloidal osmotic pressure (COP) [PBH8 and PBH4], and no PBH only albumin solution at matching COP [PBH0]. Measurement of systemic parameters, microvascular hemodynamics, capillary perfusion and intravascular and tissue O2 levels were performed at 11% Hct. Results Restitution of O2 carrying capacity with PBH13, restored higher arterial pressure, triggered vasoconstriction, low perfusion and higher peripheral resistance. PBH4 and PBH0 had lower arterial pressure than PBH13. PBH4 and PBH8 maintained higher perfusion and functional capillary density than PBH13 and PBH0. In all groups, blood gas parameters and acid-base balance were recovered proportional to microvascular perfusion. Arterial O2 tensions were improved for PBH4 and PBH8 by preventing O2 precapillary release and increasing O2 reserve. Conclusion Further studies to establish acellular Hb optimal dosage, efficacy, safety, and effects on outcome are indicated before these solutions are implemented in routine practice.

Cabrales, Pedro; Tsai, Amy G.; Intaglietta, Marcos

2009-01-01

93

Enhancement of methane combustion in microchannels: Effects of catalyst segmentation and cavities  

Microsoft Academic Search

This paper proposes a novel design concept for the enhancement of methane combustion in a microchannel that uses the combined effects of catalyst segmentation and cavities. The effects and combustion characteristics are evaluated using numerical simulation with detailed heterogeneous and homogeneous chemistries. The effects of a multi-segment catalyst and cavities on channel walls are examined and discussed in terms of

Yueh-Heng Li; Guan-Bang Chen; Hung-Wei Hsu; Yei-Chin Chao

2010-01-01

94

High-pressure calorimeter chamber tests for liquid oxygen\\/kerosene (LOX\\/RP1) rocket combustion  

Microsoft Academic Search

An experimental program was conducted to investigate the rocket combustion and heat transfer characteristics of liquid oxygen\\/kerosene (LOX\\/RP-1) mixtures at high chamber pressures. Two water-cooled calorimeter chambers of different combustion lengths were tested using 37- and 61-element oxidizer-fuel-oxidizer triplet injectors. The tests were conducted at nominal chamber pressures of 4.1, 8.3, and 13.8 MPa abs (600, 1200, and 2000 psia).

P. A. Masters; E. S. Armstrong; H. G. Price

1988-01-01

95

Enhanced combustion by jet ignition in a turbocharged cryogenic port fuel injected hydrogen engine  

Microsoft Academic Search

The Hydrogen Assisted Jet Ignition (HAJI) is a physico-chemical combustion enhancement system developed at the University of Melbourne. Jet ignition can ignite ultra-lean air\\/fuel mixtures which are far beyond the stable ignition limit of a spark plug. Jet ignition may further enhance the combustion properties of hydrogen enabling the development of a diesel-like, almost throttle-less, control of load by quantity

Alberto A. Boretti; Harry C. Watson

2009-01-01

96

Dependence of the Oxygen Enhancement Ratio on Neutron Energy  

Microsoft Academic Search

THE data reported by Barendsen and Broerse1 for the oxygen enhancement ratios in human cell cultures subjected to neutron radiation have prompted us to report the values which we have obtained for a completely different biological system-that of induction of somatic mutation in the staminal hair cells of a diploid clone (02) derived from a variety of Tradescantia occidentalis. Briefly,

J. A. Dennis; S. J. Boot

1967-01-01

97

Flow mixing enhancement from balloon pulsations in an intravenous oxygenator.  

PubMed

Computational investigations of flow mixing and oxygen transfer characteristics in an intravenous membrane oxygenator (IMO) are performed by direct numerical simulations of the conservation of mass, momentum, and species equations. Three-dimensional computational models are developed to investigate flow-mixing and oxygen-transfer characteristics for stationary and pulsating balloons, using the spectral element method. For a stationary balloon, the effect of the fiber placement within the fiber bundle and the number of fiber rings is investigated. In a pulsating balloon, the flow mixing characteristics are determined and the oxygen transfer rate is evaluated. For a stationary balloon, numerical simulations show two well-defined flow patterns that depend on the region of the IMO device. Successive increases of the Reynolds number raise the longitudinal velocity without creating secondary flow. This characteristic is not affected by staggered or non-staggered fiber placement within the fiber bundle. For a pulsating balloon, the flow mixing is enhanced by generating a three-dimensional time-dependent flow characterized by oscillatory radial, pulsatile longitudinal, and both oscillatory and random tangential velocities. This three-dimensional flow increases the flow mixing due to an active time-dependent secondary flow, particularly around the fibers. Analytical models show the fiber bundle placement effect on the pressure gradient and flow pattern. The oxygen transport from the fiber surface to the mean flow is due to a dominant radial diffusion mechanism, for the stationary balloon. The oxygen transfer rate reaches an asymptotic behavior at relatively low Reynolds numbers. For a pulsating balloon, the time-dependent oxygen-concentration field resembles the oscillatory and wavy nature of the time-dependent flow. Sherwood number evaluations demonstrate that balloon pulsations enhance the oxygen transfer rate, even for smaller flow rates. PMID:16060347

Guzmán, Amador M; Escobar, Rodrigo A; Amon, Cristina H

2005-06-01

98

Emissions of parent, nitro, and oxygenated polycyclic aromatic hydrocarbons from residential wood combustion in rural China.  

PubMed

Residential wood combustion is one of the important sources of air pollution in developing countries. Among the pollutants emitted, parent polycyclic aromatic hydrocarbons (pPAHs) and their derivatives, including nitrated and oxygenated PAHs (nPAHs and oPAHs), are of concern because of their mutagenic and carcinogenic effects. In order to evaluate their impacts on regional air quality and human health, emission inventories, based on realistic emission factors (EFs), are needed. In this study, the EFs of 28 pPAHs (EF(PAH28)), 9 nPAHs (EF(PAHn9)), and 4 oPAHs (EF(PAHo4)) were measured for residential combustion of 27 wood fuels in rural China. The measured EF(PAH28), EF(PAHn9), and EF(PAHo4) for brushwood were 86.7 ± 67.6, 3.22 ± 1.95 × 10(-2), and 5.56 ± 4.32 mg/kg, which were significantly higher than 12.7 ± 7.0, 8.27 ± 5.51 × 10(-3), and 1.19 ± 1.87 mg/kg for fuel wood combustion (p < 0.05). Sixteen U.S. EPA priority pPAHs contributed approximately 95% of the total of the 28 pPAHs measured. EFs of pPAHs, nPAHs, and oPAHs were positively correlated with one another. Measured EFs varied obviously depending on fuel properties and combustion conditions. The EFs of pPAHs, nPAHs, and oPAHs were significantly correlated with modified combustion efficiency and fuel moisture. Nitro-naphthalene and 9-fluorenone were the most abundant nPAHs and oPAHs identified. Both nPAHs and oPAHs showed relatively high tendencies to be present in the particulate phase than pPAHs due to their lower vapor pressures. The gas-particle partitioning of freshly emitted pPAHs, nPAHs, and oPAHs was primarily controlled by organic carbon absorption. PMID:22765266

Shen, Guofeng; Tao, Shu; Wei, Siye; Zhang, Yanyan; Wang, Rong; Wang, Bin; Li, Wei; Shen, Huizhong; Huang, Ye; Chen, Yuanchen; Chen, Han; Yang, Yifeng; Wang, Wei; Wang, Xilong; Liu, Wenxin; Simonich, Staci L M

2012-07-17

99

Low oxygen tension enhances hepatitis C virus replication.  

PubMed

Low oxygen tension exerts a significant effect on the replication of several DNA and RNA viruses in cultured cells. In vitro propagation of hepatitis C virus (HCV) has thus far been studied under atmospheric oxygen levels despite the fact that the liver tissue microenvironment is hypoxic. In this study, we investigated the efficiency of HCV production in actively dividing or differentiating human hepatoma cells cultured under low or atmospheric oxygen tensions. By using both HCV replicons and infection-based assays, low oxygen was found to enhance HCV RNA replication whereas virus entry and RNA translation were not affected. Hypoxia signaling pathway-focused DNA microarray and real-time quantitative reverse transcription-PCR (qRT-PCR) analyses revealed an upregulation of genes related to hypoxic stress, glycolytic metabolism, cell growth, and proliferation when cells were kept under low (3% [vol/vol]) oxygen tension, likely reflecting cell adaptation to anaerobic conditions. Interestingly, hypoxia-mediated enhancement of HCV replication correlated directly with the increase in anaerobic glycolysis and creatine kinase B (CKB) activity that leads to elevated ATP production. Surprisingly, activation of hypoxia-inducible factor alpha (HIF-?) was not involved in the elevation of HCV replication. Instead, a number of oncogenes known to be associated with glycolysis were upregulated and evidence that these oncogenes contribute to hypoxia-mediated enhancement of HCV replication was obtained. Finally, in liver biopsy specimens of HCV-infected patients, the levels of hypoxia and anaerobic metabolism markers correlated with HCV RNA levels. These results provide new insights into the impact of oxygen tension on the intricate HCV-host cell interaction. PMID:23269812

Vassilaki, N; Kalliampakou, K I; Kotta-Loizou, I; Befani, C; Liakos, P; Simos, G; Mentis, A F; Kalliaropoulos, A; Doumba, P P; Smirlis, D; Foka, P; Bauhofer, O; Poenisch, M; Windisch, M P; Lee, M E; Koskinas, J; Bartenschlager, R; Mavromara, P

2012-12-26

100

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

101

Development of Nanofiller-Modulated Polymeric Oxygen Enrichment Membranes for Reduction of Nitrogen Oxides in Coal Combustion  

Microsoft Academic Search

North Carolina A&T State University in Greensboro, North Carolina, has undertaken this project to develop the knowledge and the material to improve the oxygen-enrichment polymer membrane, in order to provide high-grade oxygen-enriched streams for coal combustion and gasification applications. Both experimental and theoretical approaches were used in this project. The membranes evaluated thus far include single-walled carbon nano-tube, nano-fumed silica

Jianzhong Lou; Shamsuddin Ilias

2010-01-01

102

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

103

A hybrid power generation system utilizing solar thermal energy with CO 2 recovery based on oxygen combustion method  

Microsoft Academic Search

A CO2-recovering power generation system utilizing solar thermal energy was proposed. In the system, relatively low temperature saturated steam around 200 °C is produced by using solar thermal energy and is utilized as the working fluid of a gas turbine in which generated CO2 is recovered based on the method of oxygen combustion. Solar thermal utilization efficiency becomes considerably high

Pyong Sik Pak; Takeshi Hatikawa; Yutaka Suzuki

1995-01-01

104

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

105

Determination of non-metallic elements in actinide complexes by oxygen flask combustion (OFC): chlorine and fluorine.  

National Technical Information Service (NTIS)

The oxygen flask combustion followed by ion selective electrode measurement has been found to be the most suitable from the point of view of elegance and simplicity for the determination of chlorine and fluorine in actinide complexes. The method has been ...

P. B. Ruikar M. S. Nagar M. S. Subramanian

1989-01-01

106

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

107

THE USE OF CO 2 AND COMBUSTION GASES FOR ENHANCED OIL RECOVERY IN RUSSIA  

Microsoft Academic Search

The use of carbon dioxide and combustion gases in EOR technologies is of interest from the point of view of CO2 geological sequestration. During the period of 1980-1990 large-scale pilot tests were carried out in Russia to utilize carbon dioxide and combustion gases, formed at different petrochemical production plants, to enhance oil recovery in different hydrocarbon fields. The analysis of

V. A. Kuvshinov

108

Oxygen-enhanced wet thermal oxidation of GaAs  

Microsoft Academic Search

An oxygen-enhanced wet thermal oxidation process is used to grow smooth, uniform, insulating native oxides of GaAs. At 420 °C, a maximum linear growth rate of 4.8 nm\\/min is observed for oxidation in water vapor with 2000 ppm O2 added relative to the N2 carrier gas, with growth ceasing by 7000 ppm. Films as thick as 800 nm with surface

J. F. Bauters; R. E. Fenlon; C. S. Seibert; W. Yuan; J. S. B. Plunkett; J. Li; D. C. Hall

2011-01-01

109

Lignocellulosic fiber charge enhancement by catalytic oxidation during oxygen delignification.  

PubMed

A series of one-stage oxygen delignification treatments with a softwood (SW) kraft pulp were studied employing 0.0-0.5% of a bismuth ruthenium pyrochlore oxide catalyst. The results demonstrated that a 0.09-0.18% charge of catalyst in an oxygen stage provided a 52.2-116.0% increase of carboxylic acid groups in the cellulosic component of kraft pulps without a significant decrease in fiber viscosity. A 3-factor at 3-level (L(9)3(3)) orthogonal experimental design was used to identify the main factors influencing acid group formation in pulp carbohydrates. The relative significance of experimental parameters for polysaccharide acid group formation was the molar equivalent NaOH, oxygen pressure, and finally, reaction temperature under the experimental conditions studied. The optimized reaction parameters for fiber charge development were shown to be 85-100 degrees C, 2.5% NaOH, and 800-960 kPa oxygen pressure. Pulps with higher fiber carboxylic acid content introduced by catalytic oxidation during oxygen delignification yielded a 10.9-33.7% increase in fiber charge after elemental chlorine free (ECF) pulp bleaching. The enhanced fiber charge resulted in 6.7-17.1% increase in paper sheet tensile index at comparable pulp viscosity. PMID:17107682

Zhang, Dongcheng; Chai, Xin-Sheng; Pu, Yunqiao; Ragauskas, Arthur J

2006-10-26

110

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

111

Mechanism of singlet oxygen chemiluminescence enhancement by human serum albumin  

NASA Astrophysics Data System (ADS)

Fluoresceinyl Cypridina Luciferin Analog (FCLA) is a chemiluminescence (CL) probe for detecting reactive oxygen species (ROS). Its detection efficiency of singlet oxygen can be significantly enhanced in the presence of human serum albumin (HSA). In the current study, the mechanism of the FCLA-HSA CL system is studied by means of direct CL measurement and spectroscopy techniques. Our results show that FCLA can combine with HSA via a single binding site to form a complex. The CL efficiency of the system is largely governed by an inter-system energy transfer between the two components upon interaction with singlet oxygen. The CL production reaches maximum in a synergetic manner when equal amount of FCLA and HSA are present simultaneously, but the production is less efficient at other ratios. This suggests that the FCLA-HSA system maybe used as a singlet oxygen detecting technique with higher sensitivity compared with that of conventional CL techniques. It may also provide a potential new technique for quantitatively analyze the presence of HSA in a sample.

Zhou, Jing; Xing, Da; Chen, Qun

2006-03-01

112

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

113

Hydrogen-oxygen reaction mechanism and its implication to hydrogen engine combustion  

Microsoft Academic Search

Combustion of hydrogen with air is receiving increasing attention in the future energy scenario. This paper broadly discusses the hydrogen combustion techniques in various thermal systems. A more elaborate discussion has been made with respect to internal combustion engines where a big role for hydrogen is envisioned particularly in the present context of energy crisis and environmental degradation.

L. M. Das

1996-01-01

114

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

115

Combustion  

NSDL National Science Digital Library

In this chemistry activity, learners discover that the weight of the product of combustion is greater than that of the starting material. Learners will compare the weight of steel wool before and after it is heated. Learners are asked to consider why the steel wool weighs more (oxidation) as well as write the balanced chemical equation for the burning of steel. This activity uses an open flame; adult supervision is recommended. The resource includes notes for educators and extension ideas.

House, The S.

2013-05-15

116

Reference concepts for a space-based hydrogen-oxygen combustion, turboalternator, burst power system  

NASA Astrophysics Data System (ADS)

This report describes reference concepts for a hydrogen-oxygen combustion, turboalternator power system that supplies power during battle engagement to a space-based, ballistic missile defense platform. All of the concepts are open that is, they exhaust hydrogen or a mixture of hydrogen and water vapor into space. We considered the situation where hydrogen is presumed to be free to the power system because it is also needed to cool the platform's weapon and the situation where hydrogen is not free and its mass must be added to that of the power system. We also considered the situation where water vapor is an acceptable exhaust and the situation where it is not. The combination of these two sets of situations required four different power generation systems, and this report describes each, suggests parameter values, and estimates masses for each of the four. These reference concepts are expected to serve as a baseline to which other types of power systems can be compared, and they are expected to help guide technology development efforts in that they suggest parameter value ranges that will lead to optimum system designs.

Edenburn, Michael W.

1990-07-01

117

OXYGEN-ENRICHED COAL COMBUSTION WITH CARBON DIOXIDE RECYCLE AND RECOVERY: SIMULATION AND EXPERIMENTAL STUDY  

SciTech Connect

Two computational problems were worked on for this study. The first chapter examines the option of coal combustion using oxygen feed with carbon dioxide recycle to control the adiabatic flame temperature. Computer simulations using an existing state-of-the-art 3-dimensional computer code for turbulent reacting flows with reacting particles were employed to study the effects of increased carbon dioxide mole fraction on the char burnout, radiant heat transfer, metal partitioning, and NOx formation. The second chapter compares assumptions for the CO/CO{sub 2} ratio at the surface of mineral inclusions made in previous studies to predictions obtained from a pseudo-steady state kinetic model (SKIPPY) for a single porous particle. The detailed kinetic simulations from SKIPPY for varying particle sizes and bulk gas compositions were used to develop algebraic expressions for the CO/CO{sub 2} ratio that can be incorporated into metal vaporization sub-models run as a post processor to detailed furnace simulations. Vaporization rate controls the formation of metal-enriched sub-micron particles in pulverized coal fired power plants.

John M. Veranth; Gautham Krishnamoorthy

2002-02-28

118

Reference concepts for a space-based hydrogen-oxygen combustion, turboalternator, burst power system  

SciTech Connect

This report describes reference concepts for a hydrogen-oxygen combustion, turboalternator power system that supplies power during battle engagement to a space-based, ballistic missile defense platform. All of the concepts are open''; that is, they exhaust hydrogen or a mixture of hydrogen and water vapor into space. We considered the situation where hydrogen is presumed to be free to the power system because it is also needed to cool the platform's weapon and the situation where hydrogen is not free and its mass must be added to that of the power system. We also considered the situation where water vapor is an acceptable exhaust and the situation where it is not. The combination of these two sets of situations required four different power generation systems, and this report describes each, suggests parameter values, and estimates masses for each of the four. These reference concepts are expected to serve as a baseline'' to which other types of power systems can be compared, and they are expected to help guide technology development efforts in that they suggest parameter value ranges that will lead to optimum system designs. 7 refs., 18 figs., 5 tabs.

Edenburn, M.W.

1990-07-01

119

An aerosol rapid compression machine for studying energetic-nanoparticle-enhanced combustion of liquid fuels  

Microsoft Academic Search

The use of energetic nanoparticles offers a promising means of adjusting the reactivity of liquid fuels for enhanced combustion stability in next generation propulsion systems. This work outlines the development of a novel aerosol rapid compression machine (RCM) for studying the impact of energetic nanoparticles on reducing the ignition delay of liquid fuels, and a proof-of-concept demonstration is presented using

Casey Allen; Gaurav Mittal; Chih-Jen Sung; Elisa Toulson; Tonghun Lee

2011-01-01

120

The Tapioca Bomb: A Demonstration to Enhance Learning about Combustion and Chemical Safety  

ERIC Educational Resources Information Center

|In any demonstration to students, producing light and sound usually ensures interest and can enhance understanding and retention of the concepts involved. A guided inquiry (Predict, Observe, Explain: POE) approach was used to involve the students actively in their learning about the explosive combustion of fine flour particles in air in the…

Keeratichamroen, Wasana; Dechsri, Precharn; Panijpan, Bhinyo; Ruenwongsa, Pintip

2010-01-01

121

Enhanced oxygen delivery induced by perfluorocarbon emulsions in capillary tube oxygenators.  

PubMed

Previous studies showed that a new generation of perfluorocarbon (PFC) emulsions increased tissue PO2 in the cat retina to a degree that could not be explained by the small increase in arterial O2 content seen after the infusion of low doses of 1 g PFC/kg body weight. It seems that increased O2 delivery at the tissue level after PFC infusion is caused by a local effect in the microcirculation. The authors studies this effect in vitro at steady state in a closed loop circuit, consisting of one of two types of capillary tube oxygenators, deoxygenator(s), a reservoir bag filled with anticoagulated bovine blood or saline (control), and a roller pump, to see if the addition of PFC would have an effect on the PO2 difference (delta PO2) across the capillary tube membrane oxygenator at a blood flow rate of 3 l/min. Perfluorocarbon was added in three incremental doses, each giving about 0.7 vol% of PFC. The delta PO2 across the oxygenator was measured before and after each dose. The mean percent increases in delta PO2 in blood for two types of oxygenators were 19.2 +/- 8% (mean +/- SD, n = 6, P = 0.002) and 9.9 +/- 4% (n = 3, P = 0.05), respectively, whereas the mean percent change in delta PO2 in saline was -4.9 +/- 2% (n = 2, P = 0.2). Inlet PO2s to the oxygenator were only minimally increased. The authors conclude that O2 delivery was significantly enhanced after injection of PFC in blood in this capillary tube model. A near wall excess of PFC particles may account for the augmentation of O2 diffusion in this model. PMID:8555593

Vaslef, S N; Goldstick, T K

122

Measurements of combustion properties in a microwave enhanced flame  

SciTech Connect

Microwave induced flame speed enhancement is quantified in a laminar, premixed CH{sub 4}/air wall stagnation flat flame. Experiments were performed in a high Q microwave cavity with the cavity tuned so that the maximum microwave field is located in the vicinity of a flat flame front. Equivalence ratios were varied between 0.6 and 0.8. When the flame is radiated by a continuous wave microwave field of approximately 5 kV/cm, the flame front is observed to move towards the burner exit and stabilize at a standoff distance corresponding to a flame speed increase of up to 20%. No microwave discharge is observed, indicating that the enhanced flame speed arises from microwave energy deposited directly into the reaction zone through coupling to the weakly ionized gas in that region. Laser diagnostics were performed to quantify temperature increase, the laminar flame speed enhancement, and changes in the OH radical concentration through filtered Rayleigh scattering, particle image velocimetry, and planar laser induced fluorescence, respectively. These measurements indicate that microwave radiation may prove to be an effective means to non-invasively control and enhance flame stability in combustors. (author)

Stockman, Emanuel S.; Zaidi, Sohail H.; Miles, Richard B. [Engineering Quadrangle - Mechanical and Aerospace Engineering, Olden Street, Princeton University, Princeton, NJ 08544 (United States); Carter, Campbell D. [US Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, OH 45433 (United States); Ryan, Michael D. [Universal Technology Corporation, Dayton, OH 45332 (United States)

2009-07-15

123

Preliminary Study of Oxygen-Enhanced Longitudinal Relaxation in MRI: A Potential Novel Biomarker of Oxygenation Changes in Solid Tumors  

SciTech Connect

Purpose: There is considerable interest in developing non-invasive methods of mapping tumor hypoxia. Changes in tissue oxygen concentration produce proportional changes in the magnetic resonance imaging (MRI) longitudinal relaxation rate (R{sub 1}). This technique has been used previously to evaluate oxygen delivery to healthy tissues and is distinct from blood oxygenation level-dependent (BOLD) imaging. Here we report application of this method to detect alteration in tumor oxygenation status. Methods and materials: Ten patients with advanced cancer of the abdomen and pelvis underwent serial measurement of tumor R{sub 1} while breathing medical air (21% oxygen) followed by 100% oxygen (oxygen-enhanced MRI). Gadolinium-based dynamic contrast-enhanced MRI was then performed to compare the spatial distribution of perfusion with that of oxygen-induced DELTAR{sub 1}. Results: DELTAR{sub 1} showed significant increases of 0.021 to 0.058 s{sup -1} in eight patients with either locally recurrent tumor from cervical and hepatocellular carcinomas or metastases from ovarian and colorectal carcinomas. In general, there was congruency between perfusion and oxygen concentration. However, regional mismatch was observed in some tumor cores. Here, moderate gadolinium uptake (consistent with moderate perfusion) was associated with low area under the DELTAR{sub 1} curve (consistent with minimal increase in oxygen concentration). Conclusions: These results provide evidence that oxygen-enhanced longitudinal relaxation can monitor changes in tumor oxygen concentration. The technique shows promise in identifying hypoxic regions within tumors and may enable spatial mapping of change in tumor oxygen concentration.

O'Connor, James P.B. [Imaging Science and Biomedical Engineering, University of Manchester, Manchester (United Kingdom) and Cancer Research UK Department of Medical Oncology, Christie Hospital, Manchester (United Kingdom); Naish, Josephine H.; Parker, Geoff J.M. [Imaging Science and Biomedical Engineering, University of Manchester, Manchester (United Kingdom); Waterton, John C. [Imaging Science and Biomedical Engineering, University of Manchester, Manchester (United Kingdom); AstraZeneca, Cheshire (United Kingdom); Watson, Yvonne [Imaging Science and Biomedical Engineering, University of Manchester, Manchester (United Kingdom); Jayson, Gordon C. [Cancer Research UK Department of Medical Oncology, Christie Hospital, Manchester (United Kingdom); Buonaccorsi, Giovanni A.; Cheung, Sue; Buckley, David L.; McGrath, Deirdre M. [Imaging Science and Biomedical Engineering, University of Manchester, Manchester (United Kingdom); West, Catharine M.L. [Academic Department of Radiation Oncology, University of Manchester, Manchester (United Kingdom); Davidson, Susan E. [Department of Clinical Oncology, Christie Hospital, Manchester (United Kingdom); Roberts, Caleb; Mills, Samantha J. [Imaging Science and Biomedical Engineering, University of Manchester, Manchester (United Kingdom); Mitchell, Claire L.; Hope, Lynn; Ton, N. Chan [Cancer Research UK Department of Medical Oncology, Christie Hospital, Manchester (United Kingdom); Jackson, Alan [Imaging Science and Biomedical Engineering, University of Manchester, Manchester (United Kingdom)

2009-11-15

124

DEVELOPMENT OF AN ENHANCED COMBUSTION LOW NOx PULVERIZED COAL BURNER  

Microsoft Academic Search

For more than two decades, ALSTOM Power Inc. (ALSTOM) has developed a range of low cost, in-furnace technologies for NOx emissions control for the domestic U.S. pulverized coal fired boiler market. This includes the internally developed TFS 2000TM firing system, and various enhancements to it developed in concert with the U.S. Department of Energy (DOE). As of the date of

Galen Richards; David Towle; Robert Lewis; Kevin Connolly; Richard Donais; Todd Hellewell

125

Oxygen-enhanced wet thermal oxidation of GaAs  

NASA Astrophysics Data System (ADS)

An oxygen-enhanced wet thermal oxidation process is used to grow smooth, uniform, insulating native oxides of GaAs. At 420 °C, a maximum linear growth rate of 4.8 nm/min is observed for oxidation in water vapor with 2000 ppm O2 added relative to the N2 carrier gas, with growth ceasing by 7000 ppm. Films as thick as 800 nm with surface roughness as low as 0.2 nm are demonstrated. In fabricated metal-oxide-semiconductor capacitors, a 412 nm thick native oxide film exhibits a factor of ~2700 reduction in leakage current density at 1 V relative to a direct metal (Au:Ti) to GaAs contact.

Bauters, J. F.; Fenlon, R. E.; Seibert, C. S.; Yuan, W.; Plunkett, J. S. B.; Li, J.; Hall, D. C.

2011-10-01

126

Efficient photosensitized oxygenations in phase contact enhanced microreactors.  

PubMed

A transparent dual-channel microreactor with highly enhanced contact area-to-volume ratio was fabricated for efficient photosensitized oxygenations. The dual-channel microreactor shielded with polyvinylsilazane (PVSZ) consisting of an upper channel for liquid flow and a lower channel for O(2) flow, allows sufficient phase contact along the parallel channels through a gas permeable PDMS membrane for maintaining the O(2) saturated solution. Under full exposure of reactants to light, the reactions in high concentration are completed in minutes rather than hours that it takes to complete in a batch reactor. Moreover, the scale-up process using the microreactor revealed higher productivity than the batch reactor, which would be valuable for the practical applications in a broad range of gas-liquid chemical reactions. PMID:21499614

Park, Chan Pil; Maurya, Ram Awatar; Lee, Jang Han; Kim, Dong-Pyo

2011-04-15

127

Laser Diagnostics of Combustion Enhancement on a CH4/Air Bunsen Flame by Dielectric Barrier Discharge  

NASA Astrophysics Data System (ADS)

We investigate plasma-assisted combustion for premixed CH4/air Bunsen flames. Dielectric barrier discharge (DBD) is employed to produce non-equilibrium plasma for combustion enhancement. The transient planar laser induced fluorescence (PLIF) technique of CH and OH radicals is used to image reaction zones for enhancement measurement, and the emission spectra of the Bunsen flame are monitored to explore the kinetics mechanism. From the drift of radicals in PLIF images, the quantitative enhancement of plasma on the flame velocities of premixed methane/air flames is experimentally measured, and the data show that the flame velocities are increased by at least 15% in the presented equivalence ratio range. Furthermore, the well analyzed emission spectra of the Bunsen flame (300–800 nm) with/without DBD reveal that the emissions as well as the concentrations of the crucial radicals (like C2, CH, OH etc.) in combustion all are intensified greatly by the discharge. In addition, the appearance of excited spectral bands of N2 and N+2 during discharge indicates that the premixed gas is also heated and ionized partially by the DBD.

Zhang, Shao-Hua; Yu, Xi-Long; Chen, Li-Hong; Zhang, Xin-Yu

2013-08-01

128

Development of Nanofiller-Modulated Polymeric Oxygen Enrichment Membranes for Reduction of Nitrogen Oxides in Coal Combustion  

SciTech Connect

North Carolina A&T State University in Greensboro, North Carolina, has undertaken this project to develop the knowledge and the material to improve the oxygen-enrichment polymer membrane, in order to provide high-grade oxygen-enriched streams for coal combustion and gasification applications. Both experimental and theoretical approaches were used in this project. The membranes evaluated thus far include single-walled carbon nano-tube, nano-fumed silica polydimethylsiloxane (PDMS), and zeolite-modulated polyimide membranes. To document the nanofiller-modulated polymer, molecular dynamics simulations have been conducted to calculate the theoretical oxygen molecular diffusion coefficient and nitrogen molecular coefficient inside single-walled carbon nano-tube PDMS membranes, in order to predict the effect of the nano-tubes on the gas-separation permeability. The team has performed permeation and diffusion experiments using polymers with nano-silica particles, nano-tubes, and zeolites as fillers; studied the influence of nano-fillers on the self diffusion, free volume, glass transition, oxygen diffusion and solubility, and perm-selectivity of oxygen in polymer membranes; developed molecular models of single-walled carbon nano-tube and nano-fumed silica PDMS membranes, and zeolites-modulated polyimide membranes. This project partially supported three graduate students (two finished degrees and one transferred to other institution). This project has resulted in two journal publications and additional publications will be prepared in the near future.

Jianzhong Lou; Shamsuddin Ilias

2010-12-31

129

High Brightness Imaging for Real Time Measurement of Shock, Particle, and Combustion Fronts Produced by Enhanced Blast Explosives.  

National Technical Information Service (NTIS)

High brightness imaging (HBI) has been used to study the structure of the leading shock, particles immediately behind the leading shock, and the following contact surface of combustion front (i.e., the 'fireball') produced during testing of enhanced blast...

K. L. McNesby B. E. Homan R. E. Lottero

2004-01-01

130

Mapping of oxygen by imaging lipids relaxation enhancement: A potential sensitive endogenous MRI contrast to map variations in tissue oxygenation.  

PubMed

PURPOSE: Because of its paramagnetic properties, oxygen may act as an endogenous magnetic resonance imaging contrast agent by changing proton relaxation rates. Changes in tissue oxygen concentrations have been shown to produce changes in relaxation rate R(1) of water. The aim of the study was to improve the sensitivity of oxygen enhanced R(1) imaging by exploiting the higher solubility of oxygen in lipids (as compared with water) to sensitively monitor changes in tissue oxygen levels by selectively measuring the R(1) of lipids. METHODS: The method, with the acronym "MOBILE" (mapping of oxygen by imaging lipids relaxation enhancement), was applied in different mouse models of hypoxic processes on a 11.7 T magnetic resonance imaging system. MOBILE was compared with R*(2) , R(1) of water, and with pO(2) measurements (using electron paramagnetic resonance oximetry). MOBILE was also applied in the brain of healthy human volunteers exposed to an oxygen breathing challenge on a 3 T magnetic resonance imaging system. RESULTS: MOBILE was shown to be able to monitor changes in oxygenation in tumor, peripheral, liver, and brain tissues. The clinical translation was demonstrated in human volunteers. CONCLUSION: MOBILE arises as a promising noninvasive and sensitive tool for diagnosis and therapeutic guidance in disorders involving hypoxia. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc. PMID:23023932

Jordan, Bénédicte F; Magat, Julie; Colliez, Florence; Ozel, Elif; Fruytier, Anne-Catherine; Marchand, Valérie; Mignion, Lionel; Bouzin, Caroline; Cani, Patrice D; Vandeputte, Caroline; Feron, Olivier; Delzenne, Nathalie; Himmelreich, Uwe; Denolin, Vincent; Duprez, Thierry; Gallez, Bernard

2012-09-28

131

Physiological Role of Nitric Oxide as an Enhancer of Oxygen Transfer from Erythrocytes to Tissues  

Microsoft Academic Search

The present study revealed the physiological role of NO as an enhancer of oxygen release from erythrocytes to peripheral tissue by breaking or stretching the heme iron–proximal histidine bond in the ? subunit of hemoglobin (Hb), while maintaining oxygen binding capacity by restoring the bond in the lungs. Oxygen affinity was significantly decreased in blood containing NO-bound Hb ?. The

Hiroaki Kosaka; Akitoshi Seiyama

1996-01-01

132

Oxygen-diffusion limited metal combustions in Zr, Ti, and Fe foils: Time- and angle-resolved x-ray diffraction studies  

SciTech Connect

The transient phase and chemical transformations of diffusion controlled metal combustions in bulk Zr, Ti, and Fe foils have been investigated, in situ, using novel time- and angle-resolved x-ray diffraction (TARXD). The TARXD employs monochromatic synchrotron x-rays and a fast-rotating diffracted beam chopper resolving the diffraction image temporally in time-resolution of {approx}45 {mu}s along the azimuth on a 2D pixel array detector. The metal foil strips (10-25 {mu}m in thickness) are ignited using a pulsed electrical heating with a typical heating rate of {approx}10{sup 6} K/s. The x-ray results indicate that the combustion occurs in molten metals, producing a wide range of stoichiometric solid oxides. It reflects an enhanced oxygen solubility and mobility of molten metals with respect to those of solid metals. However, the initial oxides formed are mainly oxygen-deficient metal oxides of ZrO, TiO, and FeO/Fe{sub 3}O{sub 4} - the lowest suboxides stable at these high temperatures. These transition metal monoxides further react with unreacted molten metals, yielding the secondary products of Zr{sub 3}O, Ti{sub 3}O, and Ti{sub 2}O - but not in FeO/Fe{sub 3}O{sub 4}. On the other hand, the higher stoichiometric oxides of ZrO{sub 2} and TiO{sub 2} are formed in the later time only on the metal surface. These results clearly indicate that the combustion process of metal strips is diffusion limited and strongly depends on the solubility and diffusivity of oxygen into molten metals. The time-resolved diffraction data reveals no evidence for metal oxidation in solids, but a series of temperature-induced polymorphic phase transitions. The dynamic thermal expansibility of Fe measured in the present fast heating experiments is similar to those in static conditions (3.3*10{sup -5}/K vs 3.5*10{sup -5}/K for {alpha}-Fe and 6.5*10{sup -5}/K versus 7.0*10{sup -5}/K for {gamma}-Fe).

Wei, Haoyan; Yoo, Choong-Shik; Chen, Jing-Yin; Shen, Guoyin (CIW); (WSU)

2012-04-30

133

Oxygen-diffusion limited metal combustions in Zr, Ti, and Fe foils: Time- and angle-resolved x-ray diffraction studies  

NASA Astrophysics Data System (ADS)

The transient phase and chemical transformations of diffusion controlled metal combustions in bulk Zr, Ti, and Fe foils have been investigated, in situ, using novel time- and angle-resolved x-ray diffraction (TARXD). The TARXD employs monochromatic synchrotron x-rays and a fast-rotating diffracted beam chopper resolving the diffraction image temporally in time-resolution of ~45 ?s along the azimuth on a 2D pixel array detector. The metal foil strips (10-25 ?m in thickness) are ignited using a pulsed electrical heating with a typical heating rate of ~106 K/s. The x-ray results indicate that the combustion occurs in molten metals, producing a wide range of stoichiometric solid oxides. It reflects an enhanced oxygen solubility and mobility of molten metals with respect to those of solid metals. However, the initial oxides formed are mainly oxygen-deficient metal oxides of ZrO, TiO, and FeO/Fe3O4 --the lowest suboxides stable at these high temperatures. These transition metal monoxides further react with unreacted molten metals, yielding the secondary products of Zr3O, Ti3O, and Ti2O -- but not in FeO/Fe3O4. On the other hand, the higher stoichiometric oxides of ZrO2 and TiO2 are formed in the later time only on the metal surface. These results clearly indicate that the combustion process of metal strips is diffusion limited and strongly depends on the solubility and diffusivity of oxygen into molten metals. The time-resolved diffraction data reveals no evidence for metal oxidation in solids, but a series of temperature-induced polymorphic phase transitions. The dynamic thermal expansibility of Fe measured in the present fast heating experiments is similar to those in static conditions (3.3*10-5/K vs 3.5*10-5/K for ?-Fe and 6.5*10-5/K versus 7.0*10-5/K for ?-Fe).

Wei, Haoyan; Yoo, Choong-Shik; Chen, Jing-Yin; Shen, Guoyin

2012-03-01

134

Resonant enhanced multiphoton ionization studies in atomic oxygen  

SciTech Connect

In this paper we analyze two-photon-resonant three-photon ionization of atomic oxygen via the 2p/sup 3/(/sup 4/S/sup 0/)np/sup 3/P/sub 0/,1,2, and the 2p/sup 3/(/sup 4/S/sup 0/)nf /sup 3/F/sub 2/,3,4 states. The various atomic parameters required for calculating the resonant enhanced multiphoton ionization (REMPI) probabilities are obtained using quantum-defect theory. The infinite sums over nonresonant states are truncated at a finite number of terms. Our calculated two-photon excitation cross sections agree well with the results of other recent calculations and of experimental measurements. The photoionization cross section is calculated for various electron kinetic energies. The REMPI dynamics is analyzed by solving the density-matrix equations. This framework consistently takes into account the effects of saturation and ac Stark shifts. REMPI probability is seen to be quite sensitive to the initial detuning, the intensity, and the particular resonant state accessed. The photoionization cross sections also imply that due to the rapid falloff of the cross section, two-color REMPI schemes with a lower-frequency ionizing photon would increase the effective REMPI probability.

Dixit, S.N.; Levin, D.A.; McKoy, B.V.

1988-06-01

135

Gas sensor construction, particularly to determine oxygen content of combustion exhaust gases, particularly from internal combustion engines  

SciTech Connect

To facilitate manufacture of a sensor, particularly a polarographic sensor which has no sealing or heat expansion difficulties and only low heat capacity in the measuring range and electrical connections, a solid electrolyte is formed as a plate extending transversely across a bottom opening of a preferably ceramic tube, the plate having two electrodes applied to its major sides. The side facing the opening is covered with a ceramic layer having a predetermined diffusion or migration resistance to oxygen molecules. The electrical connections are formed by a conductive track extending on the inside of the ceramic tube, in contact with the sensing electrode on one side of the plate; and a counter head connected to a conductive bolt or pin and resiliently spring pressed against the electrode, and holding the plate and the diffusion barrier thereon in position in the sensor. The test gas is applied to the diffusion resistance layer through a ceramic heat storage plate, for instance, having openings therethrough, which has a film-type heater applied thereto, connected to a current source by conductive tracks positioned on the outside of the ceramic tube.

Beyer, B.; Dietz, H.; Friese, K.

1981-12-15

136

American Combustion Pyretron destruction system. Applications analysis report  

SciTech Connect

The report analyzes American Combustion's Pyretron oxygen enhanced burner system. The report discusses information on the economical advantages of this type of incineration for use in assessments at uncontrolled hazardous waste sites.

Not Available

1989-06-01

137

Determination of fluorine, chlorine and bromine in household products by means of oxygen bomb combustion and ion chromatography.  

PubMed

A method for routine determination of fluorine, chlorine and bromine in household products was developed and validated. In this work, halogen analyses were made based on oxygen bomb combustion followed by ion chromatography (IC). The chromatographic analysis was performed by an IonPac AS19 hydroxide-selective anion-exchange column, a reagent free ion chromatograph eluent generator and an anion self-regenerating suppressor in 10 min. The response was linear (r ? 0.9995) in the entire investigated domain. The limit of detection for the halogens was in the range of 2 to 9 × 10(-3) mg/L and the limit of quantification was lower than 8 mg/Kg with 20 µL of injection volume. The certified reference material of ERM-EC 681k was pretreated using an oxygen bomb combustion procedure to demonstrate the precision of the proposed method. The quantitative analysis results obtained by IC for the target elements were 797 ± 9 mg/Kg chlorine and 786 ± 25 mg/Kg bromine, which were in good agreement with the certified values of 800 ± 4 mg/Kg chlorine, 770 ± 5 mg/Kg bromine for ERM-EC 681k, respectively. This validated method was successfully applied for the analysis of fluorine, chlorine and bromine in household product samples, and the variation of halogen contained among the tested samples was remarkable. PMID:22752184

Zhang, Shuai; Zhao, Tianbo; Wang, Jia; Qu, Xiaoling; Chen, Wei; Han, Yin

2012-06-28

138

Application of MOBILE (Mapping of Oxygen By Imaging Lipids relaxation Enhancement) to Study Variations in Tumor Oxygenation.  

PubMed

The aim of the study was to sensitively monitor changes in tumor oxygen using the MOBILE (mapping of oxygen by imaging lipids relaxation enhancement) technique. This method was applied in mammary tumor mouse models on an 11.7T Bruker MRI system. MOBILE was compared with functional imaging R2*, R1 of water and with pO2 measurements (using EPR oximetry and O2-dependent fluorescence quenching measurements). MOBILE was shown to be capable to monitor changes in oxygenation in tumor tissues. PMID:23852506

Jordan, Bénédicte F; Magat, Julie; Colliez, Florence; Ozel, Elif; Fruytier, Anne-Catherine; Marchand, Valérie; Mignion, Lionel; Gallez, Bernard

2013-01-01

139

CO{sub 2} emission abatement in IGCC power plants by semiclosed cycles: Part A -- With oxygen-blown combustion  

SciTech Connect

This paper analyzes the fundamentals of IGCC power plants where carbon dioxide produced by syngas combustion can be removed, liquefied and eventually disposed, to limit the environmental problems due to the greenhouse effect. To achieve this goal, a semiclosed-loop gas turbine cycle using an highly-enriched CO{sub 2} mixture as working fluid was adopted. As the oxidizer, the syngas combustion utilizes oxygen produced by an air separation unit. Combustion gases mainly consist of CO{sub 2} and H{sub 2}O: after expansion, heat recovery and water condensation, a part of the exhausts, highly concentrated in CO{sub 2}, can be easily extracted, compressed and liquefied for storage or disposal. A detailed discussion about the configuration and the thermodynamic performance of these plants is the aim of the paper. Proper attention was paid to: (i) the modelization of the gasification section and of its integration with the power cycle, (ii) the optimization of pressure ratio due the change of the cycle working fluid, (iii) the calculation of the power consumption of the auxiliary equipment, including the compression train of the separated CO{sub 2} and the air separation unit. The resulting overall efficiency is in the 38--39% range, with status-of-the-art gas turbine technology, but resorting to a substantially higher pressure ratio. The extent of modifications to the gas turbine engine, with respect to commercial units, was therefore discussed. Relevant modifications are needed, but not involving changes in the technology. A second plant scheme will be considered in the second part of the paper, using air for syngas combustion and a physical absorption process to separate CO{sub 2} from nitrogen-rich exhausts. A comparison between the two options will be addressed there.

Chiesa, P.; Lozza, G.

1999-10-01

140

Solid Fuel - Oxygen Fired Combustion for Production of Nodular Reduced Iron to Reduce CO2 Emissions and Improve Energy Efficiencies  

SciTech Connect

The current trend in the steel industry is an increase in iron and steel produced in electric arc furnaces (EAF) and a gradual decline in conventional steelmaking from taconite pellets in blast furnaces. In order to expand the opportunities for the existing iron ore mines beyond their blast furnace customer base, a new material is needed to satisfy the market demands of the emerging steel industry while utilizing the existing infrastructure and materials handling capabilities. This demand creates opportunity to convert iron ore or other iron bearing materials to Nodular Reduced Iron (NRI) in a recently designed Linear Hearth Furnace (LHF). NRI is a metallized iron product containing 98.5 to 96.0% iron and 2.5 to 4% C. It is essentially a scrap substitute with little impurity that can be utilized in a variety of steelmaking processes, especially the electric arc furnace. The objective of this project was to focus on reducing the greenhouse gas emissions (GHG) through reducing the energy intensity using specialized combustion systems, increasing production and the use of biomass derived carbon sources in this process. This research examined the use of a solid fuel-oxygen fired combustion system and compared the results from this system with both oxygen-fuel and air-fuel combustion systems. The solid pulverized fuels tested included various coals and a bio-coal produced from woody biomass in a specially constructed pilot scale torrefaction reactor at the Coleraine Minerals Research Laboratory (CMRL). In addition to combustion, the application of bio-coal was also tested as a means to produce a reducing atmosphere during key points in the fusion process, and as a reducing agent for ore conversion to metallic iron to capture the advantage of its inherent reduced carbon footprint. The results from this study indicate that the approaches taken can reduce both greenhouse gas emissions and the associated energy intensity with the Linear Hearth Furnace process for converting iron ore to metallic iron nodules. Various types of coals including a bio-coal produced though torrefaction can result in production of NRI at reduced GHG levels. The process results coupled with earlier already reported developments indicate that this process technique should be evaluated at the next level in order to develop parameter information for full scale process design. Implementation of the process to full commercialization will require a full cost production analysis and comparison to other reduction technologies and iron production alternatives. The technical results verify that high quality NRI can be produced under various operating conditions at the pilot level.

Donald R. Fosnacht; Richard F. Kiesel; David W. Hendrickson; David J. Englund; Iwao Iwasaki; Rodney L. Bleifuss; Mathew A. Mlinar

2011-12-22

141

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

142

The influence of oxygen concentration on the combustion of a fuel/oxidizer mixture  

SciTech Connect

The aim of the present study is to investigate the influence of the O{sub 2} concentration on the combustion behaviour of a fuel/oxidizer mixture. The material tested is a ternary mixture of lactose, starch, and potassium nitrate, which has already been used in an attempt to estimate heat release rate using the FM-Global Fire Propagation Apparatus. It provides a well-controlled combustion chamber to study the evolution of the combustion products when varying the O{sub 2} concentration, between air and low oxidizer conditions. Different chemical behaviours have been exhibited. When the O{sub 2} concentration was reduced beyond 18%, large variations were observed in the CO{sub 2} and CO concentrations. This critical O{sub 2} concentration seems to be the limit before which the material only uses its own oxidizer to react. On the other hand, mass loss did not highlight this change in chemical reactions and remained similar whatever the test conditions. This presumes that the oxidation of CO into CO{sub 2} are due to reactions occurring in the gas phase especially for large O{sub 2} concentrations. This actual behaviour can be verified using a simplified flammability limit model adapted for the current work. Finally, a sensitivity analysis has been carried out to underline the influence of CO concentration in the evaluation of heat release rate using typical calorimetric methods. The results of this study provide a critical basis for the investigation of the combustion of a fuel/oxidizer mixture and for the validation of future numerical models. (author)

Biteau, H. [School of Engineering and Electronics, BRE Centre for Fire Safety Engineering, The University of Edinburgh, Edinburgh EH9 3JL (United Kingdom); Institut National de l'Environnement Industriel et des Risques, Parc Technologique Alata, Verneuil en Halatte (France); Fuentes, A. [Institut Universitaire des Systemes Thermiques Industriels (CNRS UMR 6595), Universite de Provence, 13453 Marseille Cedex 13 (France); Marlair, G. [Institut National de l'Environnement Industriel et des Risques, Parc Technologique Alata, Verneuil en Halatte (France); Torero, J.L. [School of Engineering and Electronics, BRE Centre for Fire Safety Engineering, The University of Edinburgh, Edinburgh EH9 3JL (United Kingdom)

2010-04-15

143

A model of the enhancement of combustion of coal-water slurry fuels using high intensity acoustic fields  

Microsoft Academic Search

Combustion of coal-water slurry fuels is simulated in the presence of high-intensity acoustic fields which increases heat and mass transfer from the droplets and particles, and thereby enhances the combustion. The steady-slip velocity and acoustically induced slip velocity are calculated along particle trajectories, giving the augmented Nusselt and Sherwood numbers in the presence of high-intensity acoustic fields compared with no-sound

S. Yavuzkurt; M. Y. Ha

1991-01-01

144

Application of oxygen-enriched combustion for locomotive diesel engines. Phase 1  

SciTech Connect

A thermodynamic simulation is used to study the effects of oxygen-enriched intake air on the performance and nitrogen oxide (NO) emissions of a locomotive diesel engine. The parasitic power of the air separation membrane required to supply the oxygen-enriched air is also estimated. For a given constraint on peak cylinder pressure, the gross and net power outputs of an engine operating under different levels of oxygen enrichment are compared with those obtained when a high-boost turbocharged engine is used. A 4% increase in peak cylinder pressure can result in an increase in net engine power of approximately 13% when intake air with an oxygen content of 28% by volume is used and fuel injection timing is retarded by 4 degrees. When the engine is turbocharged to a higher inlet boost, the same increase in peak cylinder pressure improves power by only 4%. If part of the significantly higher exhaust enthalpies available as a result of oxygen enrichment are recovered, the power requirements of the air separator membrane can be met, resulting in substantial net power improvements. Oxygen enrichment reduces particulate and visible smoke emissions but increases NO emissions. However, a combination of retarded fuel injection timing and post-treatment of exhaust gases may be adequate to meet the locomotive diesel engine NO{sub x} standards. Exhaust gas after-treatment and heat recovery would be required to realize the full potential of oxygen enrichment. Economic analysis shows that oxygen-enrichment technology is economically feasible and provides high returns on investment. The study also indicates the strong influence of membrane parasitic requirements and exhaust energy recovery on economic benefits. To obtain an economic advantage while using a membrane with higher parasitic power requirements, it is necessary to recover a part of the exhaust energy.

Poola, R.B.; Sekar, R.R.; Assanis, D.N.

1996-09-01

145

Lignocellulosic fiber charge enhancement by catalytic oxidation during oxygen delignification  

Microsoft Academic Search

A series of one-stage oxygen delignification treatments with a softwood (SW) kraft pulp were studied employing 0.0–0.5% of a bismuth ruthenium pyrochlore oxide catalyst. The results demonstrated that a 0.09–0.18% charge of catalyst in an oxygen stage provided a 52.2–116.0% increase of carboxylic acid groups in the cellulosic component of kraft pulps without a significant decrease in fiber viscosity. A

Dongcheng Zhang; Xin-Sheng Chai; Yunqiao Pu; Arthur J. Ragauskas

2007-01-01

146

Fibronectin coating of oxygenator membranes enhances endothelial cell attachment  

PubMed Central

Background Extracorporeal membrane oxygenation (ECMO) can replace the lungs’ gas exchange capacity in refractory lung failure. However, its limited hemocompatibility, the activation of the coagulation and complement system as well as plasma leakage and protein deposition hamper mid- to long-term use and have constrained the development of an implantable lung assist device. In a tissue engineering approach, lining the blood contact surfaces of the ECMO device with endothelial cells might overcome these limitations. As a first step towards this aim, we hypothesized that coating the oxygenator’s gas exchange membrane with proteins might positively influence the attachment and proliferation of arterial endothelial cells. Methods Sheets of polypropylene (PP), polyoxymethylpentene (TPX) and polydimethylsiloxane (PDMS), typical material used for oxygenator gas exchange membranes, were coated with collagen, fibrinogen, gelatin or fibronectin. Tissue culture treated well plates served as controls. Endothelial cell attachment and proliferation were analyzed for a period of 4 days by microscopic examination and computer assisted cell counting. Results Endothelial cell seeding efficiency is within range of tissue culture treated controls for fibronectin treated surfaces only. Uncoated membranes as well as all other coatings lead to lower cell attachment. A confluent endothelial cell layer develops on fibronectin coated PDMS and the control surface only. Conclusions Fibronectin increases endothelial cells’ seeding efficiency on different oxygenator membrane material. PDMS coated with fibronectin shows sustained cell attachment for a period of four days in static culture conditions.

2013-01-01

147

Determination of the Heats of Formation of Indium and Gallium Phosphide by the Method of Combustion in a Oxygen-Bomb Calorimeter.  

National Technical Information Service (NTIS)

The study was made in view of the lack of reliable data on the heats of formation for InP and GaP. High purity phosphides were burned under pressure of oxygen in the calorimeter. The respective heats of formation obtained in a series of combustion experim...

E. N. Ermolenko N. N. Sirota

1967-01-01

148

Transition from Branching-Chain Kinetics to Partial Equilibrium in the Combustion of Lean Hydrogen-Oxygen Mixtures in Shock Waves.  

National Technical Information Service (NTIS)

Concentration profiles of the OH radical in the shock-initiated combustion of lean hydrogen-oxygen-argon mixtures at low pressures and temperatures are found to exhibit pronounced spikes prior to attainment of partial equilibrium. It is shown that this ef...

W. C. Gardiner K. Moringa D. L. Ripley T. Takeyama

1967-01-01

149

Electrolytic Generation of Oxygen Partially Explains Electrical Enhancement of Tobramycin Efficacy against Pseudomonas aeruginosa Biofilm  

Microsoft Academic Search

The role of electrolysis products, including protons, hydroxyl ions, reactive oxygen intermediates, oxygen, hydrogen, and heat, in mediating electrical enhancement of killing of Pseudomonas aeruginosa biofilms by tobramycin (the bioelectric effect) was investigated. The log reduction in biofilm viable cell numbers compared to the numbers for the untreated positive control effected by antibiotic increased from 2.88 in the absence of

PHILIP S. STEWART; WANIDA WATTANAKAROON; LU GOODRUM; SUSANA M. FORTUN; BRUCE R. MCLEOD

1999-01-01

150

STRENGTH ENHANCEMENT OF A FIBER NETWORK BY CARBOXYMETHYL CELLULOSE DURING OXYGEN DELIGNIFICATION OF KRAFT PULP  

Microsoft Academic Search

Sorption of carboxymethyl cellulose (CMC) on the fiber surface was applied during oxygen delignification to enhance the strength properties of softwood kraft pulp. Unlike many previous efforts, the focus was not set on the improvement of selectivity of oxygen delignification, i.e. retaining stable viscosity vs. decreasing kappa number. Instead, without an improved selectivity, handsheets from CMC-treated fibers exhibited a 15%

Eero Kontturi; Mia Mitikka-Eklund; Tapani Vuorinen

151

Materials for temperature independent resistive oxygen sensors for combustion exhaust gas control  

Microsoft Academic Search

Acceptor and donor doped SrTi1?xFexO3?? materials for novel temperature independent resistive oxygen sensors for lean-burn engine exhaust gases were prepared and characterized by X-ray diffraction. Their electrical resistance, R, was investigated in the oxygen partial pressure range from 10?4 to 1 bar between 700°C and 1000°C. Doped and undoped samples with x=0.3 obey an R?pO2?1\\/5 power law. Undoped samples show

Ralf Moos; Wolfgang Menesklou; Hans-Jürgen Schreiner; Karl Heinz Härdtl

2000-01-01

152

Role of Surface Area in Oxygen Storage Capacity of Ceria–Zirconia as Soot Combustion Catalyst  

Microsoft Academic Search

Two thermal stable phases, Ce0.75Zr0.25O2 and Ce0.16Zr0.84O2, with different surface area were prepared by coprecipitation. The oxygen storage capacity (OSC) measurements were carried\\u000a out at 500 ?C under both transient (CO–O2 cycle at 0.05, 0.1 and 0.25 Hz) and stationary reaction conditions (CO pulse). In the oxygen storage\\/release process, the\\u000a rate-determine step is surface reactions when the specific surface area is lower

Qing Liang; Xiaodong Wu; Xiaodi Wu; Duan Weng

2007-01-01

153

Molecular dynamics simulation of enhanced oxygen ion diffusion in strained yttria-stabilized zirconia  

Microsoft Academic Search

The application of strain to yttria-stabilized zirconia (YSZ), which can be realized by sandwiching a thin YSZ film epitaxially between layers of a material with larger lattice constants, is proposed as a means to enhance oxygen ion mobility. The possible mechanism of such an enhancement was investigated by molecular dynamics using a CeO2-YSZ superlattice. The calculated diffusion coefficient of oxygen

Ken Suzuki; Momoji Kubo; Yasunori Oumi; Ryuji Miura; Hiromitsu Takaba; Adil Fahmi; Abhijit Chatterjee; Kazuo Teraishi; Akira Miyamoto

1998-01-01

154

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

155

METALLIZED GELLED PROPELLANTS: OXYGEN\\/RP1 \\/ALUMINUM ROCKET HEAT TRANSFER AND COMBUSTION MEASUREMENTS  

Microsoft Academic Search

A series of rocket engine heat transfer experiments using metallized gelled liquid propellants was conducted. These experiments used a small 20- to 40-lbf thrust engine composed of a modular injector, igniter, chamber and nozzle. The fuels used were traditional liquid RP-1 and gelled RP-1 with 0-, 5-, and 55-wt% loadings of aluminum particles. Gaseous oxygen was used as the oxidizer.

Bryan Palaszewski; James S. Zakany

156

Oxygen assisted laser cutting mechanism—a laminar boundary layer approach including the combustion process  

Microsoft Academic Search

The present study examines the combined effects of chemical reactions taking place between a gas jet and molten metal, the cooling effect of the jet and the evaporation of metal, during a CO2 laser cutting process. A laminar boundary layer approach was used to develop a theoretical model for the oxygen gas jet laser cutting mechanism. An experiment was carried

B. S. Yilba?; A. Z. Sahin

1995-01-01

157

Scalar dissipation rate at extinction and the effects of oxygen-enriched combustion  

Microsoft Academic Search

The strain rate at extinction was measured in the counterflow flame configuration for methane, propane, and ethane flames as a function of stoichiometric mixture fraction. To complement this, the scalar dissipation rate and flame temperature at extinction were evaluated numerically for methane, ethane, and ethylene flames. The stoichiometric mixture fraction, Zst, was varied by removing nitrogen from the air (oxygen-enriched

R. Chen; R. L. Axelbaum

2005-01-01

158

Development of a burner for the high pressure combustion of liquid fuel with oxygen  

Microsoft Academic Search

The objective of this dissertation was to develop a compact burner capable of generating heat at high rates in a confined space such as an oil well, although not confined to this use. The burner developed utilized vortex motion similar to that used in cyclone combustors and swirl burners. Number 2 fuel oil and oxygen were used as the reactants

Peperakis

1984-01-01

159

Enhancement of TFT Performance by Low Temperature Oxygen Annealing  

Microsoft Academic Search

An improvement in the electrical characteristics of TFT's is evident when the active silicon layer is given a low temperature oxygen anneal prior to the deposition of the gate dielectric. The devices were fabricated using a self-aligned polysilicon gate process on Corning 1737 glass substrates and the maximum processing temperature was 620°C. The TFT's exhibit an increase in carrier mobility,

P. T. Baine; L. J. Quinn; B. Lee; S. J. N. Mitchell; B. M. Armstrong; H. S. Gamble

1997-01-01

160

OXYGEN-ENRICHED COAL COMBUSTION WITH CARBON DIOXIDE RECYCLE AND RECOVERY: SIMULATION AND EXPERIMENTAL STUDY  

SciTech Connect

An accurate estimation of the CO/CO{sub 2} ratio at the surface of an ash inclusion in coal during combustion is necessary to predict the equilibrium partial pressure of volatile reduced metal species inside the burning particle and the rate of vaporization of metal oxides. Assumptions that have been made previously for the CO/CO{sub 2} ratio at the surface of mineral inclusions are compared to those obtained from a steady state detailed kinetics code for a single porous particle (SKIPPY). The detailed kinetic simulations from SKIPPY for varying particle sizes and bulk gas compositions were used to develop algebraic expressions for the CO/CO{sub 2} ratio that can be incorporated into metal vaporization sub-models run as a post processor to detailed furnace simulations.

John M. Veranth; Gautham Krishnamoorthy

2002-01-01

161

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

162

Ignition and combustion of ferrous metals in high pressure, high velocity, gaseous oxygen  

Microsoft Academic Search

The ignition-burn conditions of several ferrous metals, including AISI1025, AISI 4140, ductile iron and 304, 410, 17-4 PH,\\u000a and CA15 stainless steels have been determined. The oxygen conditions involved velocities of approximately 430 meters per\\u000a second (1400 feet per second) and pressures of 20 to 68 atm (300 to 1000 psig). When 1025 steel specimens were fractured in\\u000a 68 atm

Charles E. Bates; James E. Wren; Raymond Monroe; C. D. Pears

1979-01-01

163

Kinetic modeling of electronically enhanced reaction pathways in Plasma Assisted Combustion  

NASA Astrophysics Data System (ADS)

The use of plasma energy to enhance and control the chemical reactions during combustion, a technology referred to as ``plasma assisted combustion'' (PAC), can result in a variety of beneficial effects: e.g. stable lean operation, pollution reduction, and wider range of p-T operating conditions. While experimental evidence abounds, theoretical understanding of PAC is at best incomplete, and numerical tools still lack in reliable predictive capabilities. In the context of a joint experimental-numerical effort at Michigan State University, we present here a modular Python framework dedicated to the dynamic optimization of non-equilibrium PAC systems. We first describe a novel kinetic global model, which aims at exploring scaling laws in parameter space, as well as the effect of a non-Maxwellian electron energy distribution function (EEDF). With such a model, we reproduce literature results and we critically review the effect of data uncertainty and limiting assumptions. Then, we explore means of measuring a non-Maxwellian EEDF through the use of a detailed collisional-radiative model, coupled to optical emission spectroscopy. Finally, we investigate the effect of different numerical integrators, as well as customized routines specifically designed to solve stiff sparse ODE systems.

Parsey, Guy; Gü?lü, Yaman; Verboncoeur, John; Christlieb, Andrew

2012-10-01

164

Oxygen Free Radicals Enhance Ergonovine-Induced Canine Coronary Vasoconstriction  

Microsoft Academic Search

In order to examine the effects of oxygen free radicals on the ergonovine (EM)-induced coronary vasoconstriction in vivo,\\u000a we administered EM (50 ?g) into the ostium of the left coronary artery (LCA) and angiographically evaluated the change of\\u000a diameter of the left anterior descending (LAD) and the left circumflex (LCX) coronary artery in eight dogs before and after\\u000a selective administration

Taku Konno; Taku Matsubara; Shoichi Imai; Mikio Nakazawa; Yutaka Yoshida; Tomoyuki Hori; KeisukeA Suzuki; Toru Ida; Kotaro Higuchi; Yusuke Tamura; Masaru Yamazoe; Yoshifusa Aizawa

165

Longevity, oxygen toxicity and radiation-enhanced resistance to oxygen in tribolium confusum  

Microsoft Academic Search

Sublethal doses of ionizing radiation increase longevity in a variety of insects suggesting that irradiation may retard the age-dependent decline of physiological functions. There have been no systematic investigations of the response of irradiated populations to stress, however. The authors have demonstrated that resistance of adult flour beetles, Tribolium confusum, to oxygen poisoning declines progressively with age. They have examined

1985-01-01

166

Flash X-ray with image enhancement applied to combustion events  

NASA Astrophysics Data System (ADS)

Flow visualization of interior ballistic processes by use of X-rays has placed more stringent requirements on flash X-ray techniques. The problem of improving radiographic contrast of propellants in X-ray transparent chambers was studied by devising techniques for evaluating, measuring and reducing the effects of scattering from both the test object and structures in the test area. X-ray film and processing is reviewed and techniques for evaluating and calibrating these are outlined. Finally, after X-ray techniques were optimized, the application of image enhancement processing which can improve image quality is described. This technique was applied to X-ray studies of the combustion of very high burning rate (VHBR) propellants and stick propellant charges.

White, K. J.; McCoy, D. G.

1983-10-01

167

The upper airway response to pollen is enhanced by exposure to combustion particulates: a pilot human experimental challenge study.  

PubMed Central

Although human experimental studies have shown that gaseous pollutants enhance the inflammatory response to allergens, human data on whether combustion particulates enhance the inflammatory response to allergen are limited. Therefore, we conducted a human experimental study to investigate whether combustion particulates enhance the inflammatory response to aeroallergens. "Enhancement" refers to a greater-than-additive response when combustion particulates are delivered with allergen, compared with the responses when particulates and allergen are delivered alone. Eight subjects, five atopic and three nonatopic, participated in three randomized exposure-challenge sessions at least 2 weeks apart (i.e., clean air followed by allergen, particles followed by no allergen, or particles followed by allergen). Each session consisted of nasal exposure to combustion particles (target concentration of 1.0 mg/m3) or clean air for 1 hr, followed 3 hr later by challenge with whole pollen grains or placebo. Nasal lavage was performed immediately before particle or clean air exposure, immediately after exposure, and 4, 18 and 42 hr after pollen challenge. Cell counts, differentials, and measurement of cytokines were performed on each nasal lavage. In atopic but not in nonatopic subjects, when allergen was preceded by particulates, there was a significant enhancement immediately after pollen challenge in nasal lavage leukocytes and neutrophils (29.7 X 10(3) cells/mL and 25.4 X 10(3) cells/mL, respectively). This represents a 143% and 130% enhancement, respectively. The enhanced response for interleukin-4 was 3.23 pg/mL (p = 0.06), a 395% enhancement. In atopic subjects there was evidence of an enhanced response when particulates, as compared to clean air, preceded the allergen challenge.

Hauser, Russ; Rice, Timothy M; Krishna Murthy, G G; Wand, Matt P; Lewis, Daniel; Bledsoe, Toni; Paulauskis, Joseph

2003-01-01

168

Study of using oxygen-enriched combustion air for locomotive diesel engines  

SciTech Connect

A thermodynamic simulation is used to study effects of O2-enriched intake air on performance and NO emissions of a locomotive diesel engine. Parasitic power of the air separation membrane required to supply the O2-enriched air is also estimated. For a given constraint on peak cylinder pressure, gross and net power output of an engine operating under different levels of O2 enrichment are compared with those obtained when a high-boost turbocharged engine is used. A 4% increase in peak cylinder pressure can result in 13% increase in net engine power when intake air with 28 vol% O2 is used and fuel injection timing retarded by 4 degrees. When the engine is turbocharged to a higher inlet boost, the same increase in peak cylinder pressure can result in only 4% improvement in power. If part of the higher exhaust enthalpies from the O2 enrichment is recovered, the power requirements of the air separator membrane can be met. O2 enrichment with its higher combustion temperatures reduces emissions of particulates and visible smoke but increases NO emissions (by up to 3 times at 26% O2 content). Therefore, exhaust gas after-treatment and heat recovery would be required if the full potential of O2 enrichment for improving the performance of locomotive diesel engines is to be realized.

Poola, R.B.; Sekar, R. [Argonne National Lab., IL (United States); Assanis, D.N. [Michigan Univ., Ann Arbor, MI (United States); Cataldi, G.R. [Association of American Railroads, Washington, DC (United States)

1996-10-01

169

Enhancing the NO 2\\/NOx ratio in compression ignition engines by hydrogen and reformate combustion, for improved aftertreatment performance  

Microsoft Academic Search

Enhanced NO2 production (without raising total NOx) in a diesel engine combustion chamber can improve the performance of several catalytic aftertreatment systems. Thus this can facilitate a further reduction in key regulated emissions such as nitrogen oxides (NOx) and particulate matter (PM) emissions. The oxidation of NO to NO2 is an important intermediate step involved in all current aftertreatment systems

J. J. Chong; A. Tsolakis; S. S. Gill; K. Theinnoi; S. E. Golunski

2010-01-01

170

Droplet combustion in presence of airstream oscillation: Mechanisms of enhancement and hysteresis of burning rate in microgravity at elevated pressure  

Microsoft Academic Search

The enhancement and hysteresis behavior of the burning rate of single droplet combustion in the presence of airstream oscillation observed in previously performed microgravity experiments at elevated pressure up to 1.0MPa were numerically investigated. Excellent agreement with the experimental results was obtained and the mechanisms of these phenomena were examined based on precise numerical data on instantaneous droplet diameter variations

Mehdi Jangi; Hideaki Kobayashi

2010-01-01

171

A laboratory model of a hydrogen/oxygen engine for combustion and nozzle studies  

NASA Astrophysics Data System (ADS)

A small laboratory diagnostic thruster was developed in order to evaluate approaches for the use of temperature and pressure sensors for the investigation of low thrust rocket flowfields. Tests were performed at chamber pressures of about 255 kPa, 370 kPa, and 500 kPa with oxidizer/fuel mixture ratios between 4.0 and 8.0. Two gaseous hydrogen/gaseous oxygen injector designs were tested with 60 and 75 fuel film cooling. The results of hot-wire tests showed the thruster and instrumentation designs to be effective. Azimuthal temperature distributions were found to be a function of operating conditions and hardware configuration. Results indicated that small differences in injector design can result in dramatically different thruster performance and wall temperature behavior. However, the importance of these injector effects may be decreased by operating at a high fuel film cooling rate.

Morren, Sybil H.; Myers, Roger M.; Benko, Stephen E.; Arrington, Lynn A.; Reed, Brian D.

1993-06-01

172

Combustive Sound Source.  

National Technical Information Service (NTIS)

This thesis describes a unique type of low frequency underwater sound source, the Combustive Sound Source (CSS). The fundamental operating principle of CSS is the following: Electrolysis of water produces hydrogen and oxygen gas, which is a combustible mi...

P. S. Wilson

1994-01-01

173

Removing aromatic and oxygenated VOCs from polluted air stream using Pt-carbon aerogels: assessment of their performance as adsorbents and combustion catalysts.  

PubMed

Two series of Pt-catalysts were prepared by impregnation or doping of carbon aerogels and different porous textures and Pt-dispersion were obtained. The performance of the samples in the elimination of organic compounds (VOCs) by adsorption and catalytic combustion was studied and compared with the characteristics of both the VOCs and the catalysts and the interactions between them. Toluene, xylenes and acetone were selected as representative aromatic or oxygenated VOCs. The adsorption of VOCs is favoured at room temperature in the case of meso/microporous materials, but at the higher catalytic reaction temperature, the micropores volume is more important. Adsorption and catalytic combustion occur simultaneously, and are both dependent on temperature, albeit in opposite directions. The combustion of aromatic compounds takes place at a lower temperature than that required for acetone combustion, so favouring the accumulation of adsorbed VOC, something that should be avoided to minimize risks. Catalytic performance improves with the contact time and is independent of oxygen content above 5% v/v, but declines significantly below this limit. PMID:21872395

Maldonado-Hódar, Francisco José

2011-08-05

174

A laboratory model of a hydrogen/oxygen engine for combustion and nozzle studies  

NASA Astrophysics Data System (ADS)

A small laboratory diagnostic thruster was developed to augment present low thrust chemical rocket optical and heat flux diagnostics at the NASA Lewis Research Center. The objective of this work was to evaluate approaches for the use of temperature and pressure sensors for the investigation of low thrust rocket flow fields. The nominal engine thrust was 110 N. Tests were performed at chamber pressures of about 255 kPa, 370 kPa, and 500 kPa with oxidizer to fuel mixture ratios between 4.0 and 8.0. Two gaseous hydrogen/gaseous oxygen injector designs were tested with 60 percent and 75 percent fuel film cooling. The thruster and instrumentation designs were proven to be effective via hot fire testing. The thruster diagnostics provided inner wall temperature and static pressure measurements which were compared to the thruster global performance data. For several operating conditions, the performance data exhibited unexpected trends which were correlated with changes in the axial wall temperature distribution. Azimuthal temperature distributions were found to be a function of operating conditions and hardware configuration. The static pressure profiles showed that no severe pressure gradients were present in the rocket. The results indicated that small differences in injector design can result in dramatically different thruster performance and wall temperature behavior, but that these injector effects may be overshadowed by operating at a high fuel film cooling rate.

Morren, Sybil Huang; Myers, Roger M.; Benko, Stephen E.; Arrington, Lynn A.; Reed, Brian D.

1993-06-01

175

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

176

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

177

Efficiency evaluation of oxygen enrichment in energy conversion processes  

SciTech Connect

The extent to which energy conversion efficiencies can be increased by using oxygen or oxygen-enriched air for combustion was studied. Combustion of most fuels with oxygen instead of air was found to have five advantages: increases combustion temperature and efficiency, improves heat transfer at high temperatures, reduces nitrous oxide emissions, permits a high ration of exhaust gas recirculation and allows combustion of certain materials not combustible in air. The same advantages, although to a lesser degree, are apparent with oxygen-enriched air. The cost-effectiveness of the process must necessarily be improved by about 10% when using oxygen instead of air before such use could become justifiable on purely economic terms. Although such a modest increase appears to be attainable in real situations, this study ascertained that it is not possible to generally assess the economic gains. Rather, each case requires its own evaluation. For certain processes industry has already proven that the use of oxygen leads to more efficient plant operation. Several ideas for essentially new applications are described. Specifically, when oxygen is used with exhaust gas recirculation in external or internal combustion engines. It appears also that the advantages of pulse combustion can be amplified further if oxygen is used. When burning wet fuels with oxygen, direct steam generation becomes possible. Oxygen combustion could also improve processes for in situ gasification of coals, oil shales, peats, and other wet fuels. Enhanced oil recovery by fire flooding methods might also become more effective if oxygen is used. The cold energy contained in liquid oxygen can be substantially recovered in the low end of certain thermodynamic cycles. Further efforts to develop certain schemes for using oxygen for combustion appear to be justified from both the technical and economic viewpoints.

Bomelburg, H.J.

1983-12-01

178

The Effect of Varying Magnetic Field Gradient on Combustion Dynamic  

NASA Astrophysics Data System (ADS)

The focus of the recent experimental research is to provide control of the combustion dynamics and complex measurements (flame temperature, heat production rate, and composition of polluting emissions) for pelletized wood biomass using a non-uniform magnetic field that produces magnetic force interacting with magnetic moment of paramagnetic oxygen. The experimental results have shown that a gradient magnetic field provides enhanced mixing of the flame compounds by increasing combustion efficiency and enhancing the burnout of volatiles.

Suzdalenko, Vera; Zake, Maija; Barmina, Inesa; Gedrovics, Martins

2011-01-01

179

Oxygen plasma surface modification enhances immobilization of simvastatin acid.  

PubMed

Simvastatin acid (SVA) has been reported to stimulate bone formation with increased expression of BMP-2. Therefore, immobilization of SVA onto dental implants is expected to promote osteogenesis at the bone tissue/implant interface. The aim of this study was to evaluate the immobilization behavior of SVA onto titanium (Ti), O(2)-plasma treated titanium (Ti + O(2)), thin-film coatings of hexamethyldisiloxane (HMDSO), and O(2)-plasma treated HMDSO (HMDSO + O(2)) by using the quartz crystal microbalance-dissipation (QCM-D) technique. HMDSO surfaces were activated by the introduction of an OH group and/or O(2)-functional groups by O(2)-plasma treatment. In contrast, titanium surfaces showed no appreciable compositional changes by O(2)-plasma treatment. The QCM-D technique enabled evaluation even at the adsorption behavior of a substance with a low molecular weight such as simvastatin. The largest amount of SVA was adsorbed on O(2)-plasma treated HMDSO surfaces compared to untreated titanium, HMDSO-coated titanium, and O(2)-plasma treated titanium. These findings suggested that the adsorption of SVA was enhanced on more hydrophilic surfaces concomitant with the presence of an OH group and/or O(2)-functional group resulting from the O(2)-plasma treatment, and that an organic film of HMDSO followed by O(2)-plasma treatment is a promising method for the adsorption of SVA in dental implant systems. PMID:16543663

Yoshinari, Masao; Hayakawa, Tohru; Matsuzaka, Kenichi; Inoue, Takashi; Oda, Yutaka; Shimono, Masaki; Ide, Takaharu; Tanaka, Teruo

2006-02-01

180

The Role of Superoxide Radicals in the Oxygen Enhancement of Radiation Damage.  

National Technical Information Service (NTIS)

The oxygen enhancement of the lethality of x-ray irradiation of dilute suspensions of Escherichia coli is strikingly diminished by superoxide dismutase or by catalase, added to the suspending medium. This implicates both O2(-) and H2O2 as agents of the O....

I. Fridovich

1977-01-01

181

The enhancement of the mixing and combustion processes in supersonic flow applied to scramjet engine  

SciTech Connect

The Reynolds averaged parabolized Navier-Stokes equations are employed for the numerical study of turbulent mixing and combustion of a supersonic hydrogen jet in a supersonic airflow. A one-equation differential turbulence model is utilized. The simplified flame sheet model is employed for the numerical simulation of the supersonic combustion. 24 refs.

Kopchenov, V.I.; Lomkov, K.E. (Tsentral'nyi NII Aviatsionnogo Motorostroeniia, Moscow (Russian Federation))

1992-07-01

182

Enhanced radiation response of a solid tumor with the artificial oxygen carrier 'albumin-heme'.  

PubMed

Tumor-cell hypoxia is one of the main factors inducing radioresistance. Enhanced tumor oxygenation has previously been achieved in an animal model using the synthetic heme-based oxygen carrier 'albumin-heme' (recombinant human serum albumin-Fe cyclohexanoil heme; rHSA-FeP). The present study was done to determine whether rHSA-FeP enhances the radiation response in an experimental tumor model. Male Donryu rats and LY80, a variant of the syngenic liver ascites tumor, were used. A total of 1 x 10(6) cells were injected into the subfascial tissue of the right thigh. The rats were divided randomly into five groups: sham (tumor implantation and sham operation); rHSA-FeP; irradiation; rHSA + irradiation; and rHSA-FeP + irradiation. Six days after, under general anesthesia, intra-arterial administration of 10 mL/kg of either 5% rHSA solution or oxygenated rHSA-FeP solution at 2.5 mL/min was done and a dose of 20 Gy was given. There were significant differences in tumor growth between the sham and irradiation groups, and between the sham and rHSA-FeP + irradiation groups. Tumor growth delay was observed and differences were significant between the sham and irradiation groups, and between the irradiation and rHSA-FeP + irradiation groups. In the present study, rHSA-FeP itself had a slight effect on tumor growth without irradiation. Enhancing the effect of rHSA-FeP on the radiation response is responsible in part for the oxygen-carrying property of rHSA-FeP. In conclusion, rHSA-FeP is a candidate radiation-enhancing drug. Arterial infusion of rHSA-FeP may serve as a local oxygenation method that enhances the radiation effect. PMID:18429955

Horinouchi, Hirohisa; Yamamoto, Hisashi; Komatsu, Teruyuki; Huang, Yubin; Tsuchida, Eishun; Kobayashi, Koichi

2008-04-21

183

Technology evaluation report: SITE (Superfund Innovative Technology Evaluation) program demonstration test. The American Combustion Pyretron Thermal Destruction System at the US EPA's (Environmental Protection Agency's) combustion research facility  

Microsoft Academic Search

A series of demonstration tests of the American Combustion, Inc., Thermal Destruction System was performed under the SITE program. This oxygen-enhanced combustion system was retrofit to the rotary-kiln incinerator at EPA's Combustion Research Facility. The system's performance was tested firing contaminated soil from the Stringfellow Superfund Site, both alone and mixed with a coal tar waste (KO87). Comparative performance with

L. Waterland; J. W. Lee

1989-01-01

184

Oxygen-enhanced MRI in temporal lobe epilepsy: diagnosis and lateralization.  

PubMed

We explored the diagnostic value of oxygen-enhanced MRI, a novel technique for measuring regional brain metabolism, in a set of normal adult volunteers and temporal lobe epilepsy patients. Eight right-handed adult normal volunteers and ten right-handed patients with temporal lobe epilepsy were studied. Six patients had lesions concordant with their epilepsy on high-resolution (3T) structural MRI. Four patients were nonlesional. Hyperoxia (oxygen enhancement, OE) was carried out by administering 100% O(2) in epochs by mask or cannula interleaved with breathing of normal atmospheric air. The T2* (blood oxygen level dependent, BOLD) signal was recorded in continuously acquired echo-planar images. Data from nine temporal lobe subregions were subjected to spectral analysis and statistical testing. OE resulted in unambiguous concordant positive T2* signal change in all subjects. Analysis of the distribution of spectral power within the temporal lobe revealed a significant (p<0.025, one-sided) group difference between normals and epilepsy patients, with seven patients exhibiting large deviations from normalcy that lateralized their disease. Two such patients had nonlesional MRIs. Oxygen-enhanced MRI is a promising metabolic imaging modality for the diagnosis and lateralization of oxidative metabolic derangement associated with lesional and nonlesional temporal lobe epilepsy. PMID:21917423

Kalamangalam, Giridhar P; Nelson, Jeffrey T; Ellmore, Timothy M; Narayana, Ponnada A

2011-09-13

185

Simultaneous imaging of tumor oxygenation and microvascular permeability using Overhauser enhanced MRI  

PubMed Central

Architectural and functional abnormalities of blood vessels are a common feature in tumors. A consequence of increased vascular permeability and concomitant aberrant blood flow is poor delivery of oxygen and drugs, which is associated with treatment resistance. In the present study, we describe a strategy to simultaneously visualize tissue oxygen concentration and microvascular permeability by using a hyperpolarized 1H-MRI, known as Overhauser enhanced MRI (OMRI), and an oxygen-sensitive contrast agent OX63. Substantial MRI signal enhancement was induced by dynamic nuclear polarization (DNP). The DNP achieved up to a 7,000% increase in MRI signal at an OX63 concentration of 1.5 mM compared with that under thermal equilibrium state. The extent of hyperpolarization is influenced mainly by the local concentration of OX63 and inversely by the tissue oxygen level. By collecting dynamic OMRI images at different hyperpolarization levels, local oxygen concentration and microvascular permeability of OX63 can be simultaneously determined. Application of this modality to murine tumors revealed that tumor regions with high vascular permeability were spatio-temporally coincident with hypoxia. Quantitative analysis of image data from individual animals showed an inverse correlation between tumor vascular leakage and median oxygen concentration. Immunohistochemical analyses of tumor tissues obtained from the same animals after OMRI experiments demonstrated that lack of integrity in tumor blood vessels was associated with increased tumor microvascular permeability. This dual imaging technique may be useful for the longitudinal assessment of changes in tumor vascular function and oxygenation in response to chemotherapy, radiotherapy, or antiangiogenic treatment.

Matsumoto, Shingo; Yasui, Hironobu; Batra, Sonny; Kinoshita, Yuichi; Bernardo, Marcelino; Munasinghe, Jeeva P.; Utsumi, Hideo; Choudhuri, Rajani; Devasahayam, Nallathamby; Subramanian, Sankaran; Mitchell, James B.; Krishna, Murali C.

2009-01-01

186

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

187

Characteristics Evaluation of a CO2-Caputuring Power Generation System with Reheat Cycle Utilizing Regenerative Oxygen-Combustion Steam-Superheater  

NASA Astrophysics Data System (ADS)

A new CO2-capturing power generation system is proposed that can be easily realized by applying conventional technologies. In the proposed system, the temperature of middle-pressure steam in a thermal power plant is raised by utilizing oxygen-combusting regenerative steam-superheater. The generated CO2 by combusting fuel in the superheater can be easily separated and captured from the exhaust gas at condenser outlet, and is liquefied. The superheated steam is used to drive a steam turbine power generation system. By adopting a high efficient combined cycle power generation system as an example, it has been shown that the proposed system can increase power output by 10.8%, decrease the CO2 emission amount of the total integrated system by 18.6% with power generation efficiency drop of 2.36% compared with the original power plant without CO2-capture, when superheated steam temperature is 750°C

Pak, Pyong Sik

188

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

189

Long term analysis of the biomass content in the feed of a waste-to-energy plant with oxygen-enriched combustion air.  

PubMed

Thermal utilization of municipal solid waste and commercial wastes has become of increasing importance in European waste management. As waste materials are generally composed of fossil and biogenic materials, a part of the energy generated can be considered as renewable and is thus subsidized in some European countries. Analogously, CO(2) emissions of waste incinerators are only partly accounted for in greenhouse gas inventories. A novel approach for determining these fractions is the so-called balance method. In the present study, the implementation of the balance method on a waste-to-energy plant using oxygen-enriched combustion air was investigated. The findings of the 4-year application indicate on the one hand the general applicability and robustness of the method, and on the other hand the importance of reliable monitoring data. In particular, measured volume flows of the flue gas and the oxygen-enriched combustion air as well as corresponding O(2) and CO(2) contents should regularly be validated. The fraction of renewable (biogenic) energy generated throughout the investigated period amounted to between 27 and 66% for weekly averages, thereby denoting the variation in waste composition over time. The average emission factor of the plant was approximately 45 g CO(2) MJ(-1) energy input or 450 g CO(2) kg(-1) waste incinerated. The maximum error of the final result was about 16% (relative error), which was well above the error (<8%) of the balance method for plants with conventional oxygen supply. PMID:21382872

Fellner, Johann; Cencic, Oliver; Zellinger, Günter; Rechberger, Helmut

2011-03-07

190

Flame temperature measurements by radar resonance-enhanced multiphoton ionization of molecular oxygen.  

PubMed

Here we report nonintrusive local rotational temperature measurements of molecular oxygen, based on coherent microwave scattering (radar) from resonance-enhanced multiphoton ionization (REMPI) in room air and hydrogen/air flames. Analyses of the rotational line strengths of the two-photon molecular oxygen C(3)?(v=2)?X(3)?(v'=0) transition have been used to determine the hyperfine rotational state distribution of the ground X(3)?(v'=0) state. Rotationally resolved 2+1 REMPI spectra of the molecular oxygen C(3)?(v=2)?X(3)?(v'=0) transition at different temperatures were obtained experimentally by radar REMPI. Rotational temperatures have been determined from the resulting Boltzmann plots. The measurements in general had an accuracy of ~±60 K in the hydrogen/air flames at various equivalence ratios. Discussions about the decreased accuracy for the temperature measurement at elevated temperatures have been presented. PMID:23033104

Wu, Yue; Sawyer, Jordan; Zhang, Zhili; Adams, Steven F

2012-10-01

191

Functional analysis of an oxygen-regulated transcriptional enhancer lying 3' to the mouse erythropoietin gene.  

PubMed Central

Erythropoietin, the major hormone controlling red-cell production, is regulated in part through oxygen-dependent changes in the rate of transcription of its gene. Using transient transfection in HepG2 cells, we have defined a DNA sequence, located 120 base pairs 3' to the poly(A)-addition site of the mouse erythropoietin gene, that confers oxygen-regulated expression on a variety of heterologous promoters. The sequence has the typical features of a eukaryotic enhancer. Approximately 70 base pairs are necessary for full activity, but reiteration restores activity to shorter inactive sequences. This enhancer operates in HepG2 and Hep3B cells, but not in Chinese hamster ovary cells or mouse erythroleukemia cells, and responds to cobalt but not to cyanide or 2-deoxyglucose, thus reflecting the physiological control of erythropoietin production accurately. Images

Pugh, C W; Tan, C C; Jones, R W; Ratcliffe, P J

1991-01-01

192

Enhanced conductivity of reduced graphene oxide decorated with aluminium oxide nanoparticles by oxygen annealing  

NASA Astrophysics Data System (ADS)

A process involving the filtration of graphene oxide (GO) dispersion through an alumina membrane, followed by oxygen annealing to synthesize alumina nanoparticles exclusively at the edges of holes or vacancies in the reduced graphene oxide (rGO) plane, is used to prepare paper-like composites with a 21% enhanced electrical conductivity. Moreover, the rGO/alumina nanocomposites have a smaller band gap and hydrophilic properties.A process involving the filtration of graphene oxide (GO) dispersion through an alumina membrane, followed by oxygen annealing to synthesize alumina nanoparticles exclusively at the edges of holes or vacancies in the reduced graphene oxide (rGO) plane, is used to prepare paper-like composites with a 21% enhanced electrical conductivity. Moreover, the rGO/alumina nanocomposites have a smaller band gap and hydrophilic properties. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr00362k

Liu, Hao; Choy, Kwang-Leong; Roe, Martin

2013-06-01

193

Root effect hemoglobin may have evolved to enhance general tissue oxygen delivery.  

PubMed

The Root effect is a pH-dependent reduction in hemoglobin-O2 carrying capacity. Specific to ray-finned fishes, the Root effect has been ascribed specialized roles in retinal oxygenation and swimbladder inflation. We report that when rainbow trout are exposed to elevated water carbon dioxide (CO2), red muscle partial pressure of oxygen (PO2) increases by 65%--evidence that Root hemoglobins enhance general tissue O2 delivery during acidotic stress. Inhibiting carbonic anhydrase (CA) in the plasma abolished this effect. We argue that CA activity in muscle capillaries short-circuits red blood cell (RBC) pH regulation. This acidifies RBCs, unloads O2 from hemoglobin, and elevates tissue PO2, which could double O2 delivery with no change in perfusion. This previously undescribed mechanism to enhance O2 delivery during stress may represent the incipient function of Root hemoglobins in fishes. PMID:23766325

Rummer, Jodie L; McKenzie, David J; Innocenti, Alessio; Supuran, Claudiu T; Brauner, Colin J

2013-06-14

194

Diamagnetic levitation enhances growth of liquid bacterial cultures by increasing oxygen availability.  

PubMed

Diamagnetic levitation is a technique that uses a strong, spatially varying magnetic field to reproduce aspects of weightlessness, on the Earth. We used a superconducting magnet to levitate growing bacterial cultures for up to 18 h, to determine the effect of diamagnetic levitation on all phases of the bacterial growth cycle. We find that diamagnetic levitation increases the rate of population growth in a liquid culture and reduces the sedimentation rate of the cells. Further experiments and microarray gene analysis show that the increase in growth rate is owing to enhanced oxygen availability. We also demonstrate that the magnetic field that levitates the cells also induces convective stirring in the liquid. We present a simple theoretical model, showing how the paramagnetic force on dissolved oxygen can cause convection during the aerobic phases of bacterial growth. We propose that this convection enhances oxygen availability by transporting oxygen around the liquid culture. Since this process results from the strong magnetic field, it is not present in other weightless environments, e.g. in Earth orbit. Hence, these results are of significance and timely to researchers considering the use of diamagnetic levitation to explore effects of weightlessness on living organisms and on physical phenomena. PMID:20667843

Dijkstra, Camelia E; Larkin, Oliver J; Anthony, Paul; Davey, Michael R; Eaves, Laurence; Rees, Catherine E D; Hill, Richard J A

2010-07-28

195

Molecular Dynamics Study of Superlattice Superionic Conductor: Enhancement of Oxygen Ion Diffusion in YSZ  

Microsoft Academic Search

A constant-volume molecular dynamics calculation has been performed for a cubic yttria-stabilized zirconia (Y2O3)c(ZrO2)1-c, where Y layers and Zr layers are alternately accumulated to form a superlattice. A considerable enhancement of the diffusion of oxygen ions was observed at the composition c=0.33, at which the diffusion coefficient in the superlattice is about three times larger than the case of a

Hideo Okazaki; Hisashi Suzuki; Katsuyoshi Ihata

1994-01-01

196

Oxygen diffusion in minihemoglobin from Cerebratulus lacteus : a locally enhanced sampling study  

Microsoft Academic Search

Heme proteins serve as a source of oxygen in nervous tissue during anoxia. The functional routes of a dioxygen (O\\u000a 2) diffusion in a novel structure of a minihemoglobin (CerHb) molecule present in worm Cerebratulus lacteus are not known. In this paper, the results of 1ns molecular dynamics simulations of this process are presented. The locally\\u000a enhanced sampling method (LES)

Slawomir Orlowski; Wieslaw Nowak

2007-01-01

197

Oxygen enhanced crack growth in nickel-based superalloys and materials damage prognosis  

Microsoft Academic Search

This paper summarizes the results from a comprehensive multidisciplinary study to better understand the role of niobium and other strengthening elements in enhancing crack growth by oxygen in nickel-based superalloys at high temperatures, and considers its importance for materials damage prognosis and life cycle engineering in high temperature service. Three ?? strengthened powder metallurgy (P\\/M) alloys, with 0, 2.5 and

Robert P. Wei; Christopher Miller; Zhifan Huang; Gary W. Simmons; D. Gary Harlow

2009-01-01

198

Enhanced conductivity of reduced graphene oxide decorated with aluminium oxide nanoparticles by oxygen annealing.  

PubMed

A process involving the filtration of graphene oxide (GO) dispersion through an alumina membrane, followed by oxygen annealing to synthesize alumina nanoparticles exclusively at the edges of holes or vacancies in the reduced graphene oxide (rGO) plane, is used to prepare paper-like composites with a 21% enhanced electrical conductivity. Moreover, the rGO/alumina nanocomposites have a smaller band gap and hydrophilic properties. PMID:23712529

Liu, Hao; Choy, Kwang-Leong; Roe, Martin

2013-05-28

199

Ultraviolet Irradiation-Dependent Fluorescence Enhancement of Hemoglobin Catalyzed by Reactive Oxygen Species  

PubMed Central

Ultraviolet (UV) light has a potent effect on biological organisms. Hemoglobin, an oxygen-transport protein, plays an irreplaceable role in sustaining life of all vertebrates. In this study we scrutinize the effects of ultraviolet irradiation (UVI) as well as visible irradiation on the fluorescence characteristics of bovine hemoglobin (BHb) in vitro. Data show that UVI results in fluorescence enhancement of BHb in a dose-dependant manner. Furthermore, UVI-induced fluorescence enhancement is significantly increased when BHb is pretreated with hydrogen peroxide (H2O2), a type of reactive oxygen species (ROS). Meanwhile, The water-soluble antioxidant vitamin C suppresses this UVI-induced fluorescence enhancement. In contrast, green light irradiation does not lead to fluorescence enhancement of BHb no matter whether H2O2 is acting on the BHb solution or not. Taken together, these results indicate that catalysis of ROS and UVI-dependent irradiation play two key roles in the process of UVI-induced fluorescence enhancement of BHb.

Pan, Leiting; Wang, Xiaoxu; Yang, Shuying; Wu, Xian; Lee, Imshik; Zhang, Xinzheng; Rupp, Romano A.; Xu, Jingjun

2012-01-01

200

Enhanced atmospheric oxygen outflow on Earth and Mars driven by a corotating interaction region  

NASA Astrophysics Data System (ADS)

Solar wind controls nonthermal escape of planetary atmospheric volatiles, regardless of the strength of planetary magnetic fields. For both Earth with a strong dipole and Mars with weak remnant fields, the oxygen ion (O+) outflow has been separately found to be enhanced during corotating interaction region (CIR) passage. Here we compared the enhancements of O+ outflow on Earth and Mars driven by a CIR in January 2008, when Sun, Earth, and Mars were approximately aligned. The CIR propagation was recorded by STEREO, ACE, Cluster, and Mars Express (MEX). During the CIR passage, Cluster observed enhanced flux of upwelling oxygen ions above the Earth's polar region, while MEX detected an increased escape flux of oxygen ions in the Martian magnetosphere. We found that (1) under a solar wind dynamic pressure increase of 2-3 nPa, the rate of increase in Martian O+ outflow flux was 1 order higher than those on Earth; and (2) as a response to the same part of the CIR body, the rate of increase in Martian O+ outflow flux was on the same order as for Earth. The comparison results imply that the dipole effectively prevents coupling of solar wind kinetic energy to planetary ions, and the distance to the Sun is also crucially important for planetary volatile loss in our inner solar system.

Wei, Y.; Fraenz, M.; Dubinin, E.; Woch, J.; Lühr, H.; Wan, W.; Zong, Q.-G.; Zhang, T. L.; Pu, Z. Y.; Fu, S. Y.; Barabash, S.; Lundin, R.; Dandouras, I.

2012-03-01

201

EFFECTS OF HYBRID REBURNING\\/SNCR STRATEGY ON NOX\\/CO REDUCTION AND THERMAL CHARACTERISTICS IN OXYGEN-ENRICHED LPG FLAME  

Microsoft Academic Search

From the view of the environmental protection against the usage of fossil fuels, a great amount of effort has been exerted to find an effective method that is not only for pollutant reduction, but also for higher thermal efficiency. In order to enhance combustion efficiency, oxygen-enriched combustion is used by increasing the oxygen ratio in the oxidizer. However, since the

CHANG YEOP LEE; SEUNG WOOK BAEK

2007-01-01

202

Enhanced Hyaluronic Acid Production of Streptococcus zooepidemicus by Shifting Dissolved Oxygen Level Based on Broth Rheology and Oxygen Mass Transfer Characteristics  

Microsoft Academic Search

This research focused on a dissolved oxygen (DO)-shifting strategy to enhance the production of hyaluronic acid (HA) by Streptococcus zooepidemicus. In this strategy, DO was controlled at above 10 ± 1% during 0–8 h and at 5 ± 0.5% during 8–18 h. The DO-shifting strategy increased the consistency index and oxygen mass transfer coefficient and decreased the flow behavior index

Long Liu; Haiquan Yang; Guocheng Du; Jian Chen; Miao Wang

2009-01-01

203

Characterization of mercury-enriched coal combustion residues from electric utilities using enhanced sorbents for mercury control  

SciTech Connect

This report evaluates changes that may occur to coal-fired power plant air pollution control residues from the use of activated carbon and other enhanced sorbents for reducing air emissions of mercury and evaluates the potential for captured pollutants leaching during the disposal or use of these residues. Leaching of mercury, arsenic, and selenium during land disposal or beneficial use of coal combustion residues (CCRs) is the environmental impact pathway evaluated in this report. Coal combustion residues refer collectively to fly ash and other air pollution control solid residues generated during the combustion of coal collected through the associated air pollution control system. This research is part of an on-going effort by US Environmental protection Agency (EPA) to use a holistic approach to account for the fate of mercury and other metals in coal throughout the life-cycle stages of CCR management. This report focuses on facilities that use injected sorbents for mercury control. It includes four facilities with activated carbon injection (ACI) and two facilities using brominated ACI. Fly ash has been obtained from each facility with and without operation of the sorbent injection technology for mercury control. Each fly ash sampled was evaluated in the laboratory for leaching as a function of pH and liquid-to-solid ratio. Mercury, arsenic and selenium were the primary constituent of interest; results for these elements are presented here. 30 refs., 30 figs., 14 tabs., 10 apps.

Sanchez, F.; Keeney, R.; Kosson, D.; Delapp, R. [Vanderbilt University, Nashville, TN (United States). Dept. of Civil and Environmental Engineering

2006-02-15

204

Cathodic current enhancement via manganese and oxygen related reactions in marine biofilms  

NASA Astrophysics Data System (ADS)

Corrosion is a threat that has economic, and environmental impacts worldwide. Many types of corrosive attack are the subject of ongoing research. One of these areas of research is microbiologically influenced corrosion, which is the enhancement and/or initiation of corrosion events caused by microorganisms. It is well known that colonies of microorganisms can enhance cathodic currents through biofilm formation. The aim of the present work was to elucidate the role of manganese in enhancing cathodic currents in the presence of biofilms. Repeated polarizations conducted in Delaware Bay waters, on biofilm coated Cr identified potentially sustainable reduction reactions. The reduction of MnO2 and the enhancement of the oxygen reduction reaction (ORR) were proven to be factors that influence cathodic current enhancement. The removal of ambient oxygen during polarizations resulted in a shutdown of cathodic current enhancement. These field data led to an exploration of the synergistic relationship between MnO2 and the ORR. Laboratory studies of the catalysis of peroxide disproportionation by MnO2 were monitored using a hanging mercury drop electrode. Experiments were run at an ambient sweater pH of 8 and pH 9, which simulated the near-surface conditions typical of cathodes immersed in seawater. Rapid reoxidation at the more basic pH was shown to allow manganese to behave as a persistent catalyst under the typical electrochemical surface conditions of a cathode. As a result a mechanism for ORR enhancement by manganese was proposed as a unique mechanism for cathodic current enhancement in biofilms. A separate field study of Delaware biofilms on stainless steel coupled to a sacrificial Al anode was carried out to identify the ORR enhancement mechanism and sustainable redox reactions at the cathode. Chemical treatments of glutaraldehyde and formaldoxime were applied to cathodes with biofilms to distinguish between enzymatic and MnO2 related ORR enhancement. The results ruled out the enzymatic catalysis of ORR and supported the catalysis by MnO2. Sustainable redox reactions at the cathode were evaluated by monitoring the cathodic current of biofilm coated stainless steel for a year under different polarization intensities. The results showed that sustainable cathodic reactions were present in marine biofilms but their influence on the cathodic current was negligible until a potential was reached where the ORR could take place. Additionally seasonal variability was observed in the enhanced cathodic current in Delaware Bay biofilms. This was attributed to the seasonal variability of manganese in the water column.

Strom, Matthew James

205

Superoxide dismutase deficiency enhances superoxide levels in brain tissues during oxygenation and hypoxia-reoxygenation.  

PubMed

To determine whether the mitochondria or cytoplasm produces superoxide during ischemia-reperfusion of the brain, we analyzed lucigenine-enhanced chemiluminescence emission in slices of brain tissue prepared from manganese-superoxide dismutase (Mn-SOD)-deficient (Sod2-deficient) and copper and zinc-superoxide dismutase (Cu,Zn-SOD)-deficient (Sod1-deficient) mice during oxygenation and hypoxia-reoxygenation. The steady-state level of chemiluminescence under oxygenated conditions was significantly enhanced by a lack of either Sod. We hypothesize that the enhanced chemiluminescence produced by Sod2 and Sod1 deficiency reflects in situ superoxide generation in the mitochondria and cytoplasm, respectively. Based on this hypothesis, the major site of intracellular superoxide generation was assumed to be the cytoplasm. However, mitochondria occupy less cellular space than the cytoplasm. In terms of volume, the superoxide concentration is assumed to be higher in mitochondria than in the cytoplasm. Mn-SOD activity was 18% of the Cu,Zn-SOD activity observed in the wild-type mouse brain. However, when mitochondrial SOD activity was expressed as per volume, it was assumed to be equal to that observed in the cytoplasm. This imbalance between superoxide and SOD activity is expected to cause mitochondrial oxidative damage. The chemiluminescence intensity increased significantly during reoxygenation and was enhanced by Sod2 deficiency but was not significantly affected by Sod1 deficiency. The superoxide concentration in the reoxygenated brain would be higher in the mitochondria than in the cytoplasm. The present study indicated that the major site of intracellular superoxide generation in the brain during oxygenation is the cytoplasm, whereas it is the mitochondria during reoxygenation. PMID:21280062

Sasaki, Toru; Shimizu, Takahiko; Koyama, Tomoko; Sakai, Masanobu; Uchiyama, Satoshi; Kawakami, Satoru; Noda, Yoshihiro; Shirasawa, Takuji; Kojima, Shuji

2011-01-28

206

Environmental enhancement of creep crack growth in Inconel 718 by oxygen and water vapor  

SciTech Connect

Inconel 718 alloy is widely used in high temperature applications. Because of its sensitivity to environmentally enhanced crack growth at high temperatures, its use has been limited to modest temperatures (i.e., below 973 K). To improve its performance and to better predict its service life, it is important to develop a better understanding of the processes of crack growth at high temperatures in this alloy. It has been shown that the creep crack growth rates (CCGR) in air are at least two orders of magnitude faster than those in vacuum or inert environments. CCGR were also found to depend strongly on temperature. Fractographic studies showed that crack growth was intergranular in air and in vacuum with brittle appearing grain boundary separation in air and extensive cavity formation in vacuum. The increased CCGR in air has been attributed to the enhancement by oxygen; principally through enhanced cavity nucleation and growth by high-pressure carbon monoxide/dioxide formed by the reactions of oxygen that diffused into the material with the grain boundary carbides. The appropriateness of this mechanism, however, may be questioned by the absence of cavitation on the crack surfaces produced in air. As such the mechanism for crack growth needs to be re-examined. Because of the presence of moisture in air, the possible influence of hydrogen needs to be considered as well. In this study, preliminary experiments were conducted to examine the process of environmentally enhanced creep crack growth in Inconel 718 alloy in terms of possible mechanisms and rate controlling processes. Creep crack growth experiments were carried out in air, oxygen (from 2.67 to 100 kPa), moist argon (water vapor) and pure argon at temperatures from 873 to 973 K.

Valerio, P.; Gao, M.; Wei, R.P. (Lehigh Univ., Bethlehem, PA (United States). Dept. of Mechanical Engineering and Mechanics)

1994-05-15

207

Enhancement of hybrid rocket combustion performance using nano-sized energetic particles  

Microsoft Academic Search

Until now, the regression rate of classical hybrid rocket engines have typically been an order of magnitude lower than solid propellant motors; thus, hybrids require a relatively large fuel surface area for a given thrust level. In addition to low linear regression rates, relatively low combustion efficiency (87 to 92%), low mass burning rates, varying oxidizer-to-fuel ratio during operation, and

Grant Alexander Risha

2003-01-01

208

FEASIBILITY STUDY OF ENHANCED COMBUSTION VIA IMPROVED WOOD STOVE FIREBOX DESIGN  

EPA Science Inventory

The paper gives results of an examination of materials that might be used within the firebox of a wood-burning stove to produce more uniform and complete combustion. Although many materials were initially considered, refractory materials appear to possess the qualities desired re...

209

Experimental and Modeling Studies of the Characteristics of Liquid Biofuels for Enhanced Combustion  

SciTech Connect

The objectives of this project have been to develop a comprehensive set of fundamental data regarding the combustion behavior of biodiesel fuels and appropriately associated model fuels that may represent biodiesels in automotive engineering simulation. Based on the fundamental study results, an auxiliary objective was to identify differentiating characteristics of molecular fuel components that can be used to explain different fuel behavior and that may ultimately be used in the planning and design of optimal fuel-production processes. The fuels studied in this project were BQ-9000 certified biodiesel fuels that are certified for use in automotive engine applications. Prior to this project, there were no systematic experimental flame data available for such fuels. One of the key goals has been to generate such data, and to use this data in developing and verifying effective kinetic models. The models have then been reduced through automated means to enable multi-dimensional simulation of the combustion characteristics of such fuels in reciprocating engines. Such reliable kinetics models, validated against fundamental data derived from laminar flames using idealized flow models, are key to the development and design of optimal engines, engine operation and fuels. The models provide direct information about the relative contribution of different molecular constituents to the fuel performance and can be used to assess both combustion and emissions characteristics. During this project, we completed a major and thorough validation of a set of biodiesel surrogate components, allowing us to begin to evaluate the fundamental combustion characteristics for B100 fuels.

E. Meeks; A. U. Modak; C.V. Naik; K. V. Puduppakkam; C. Westbrook; F. N. Egolfopoulos; T. Tsotsis; S. H. Roby

2009-07-01

210

Method of activating limestone for enhanced capture of sulfur from post combustion gases.  

National Technical Information Service (NTIS)

Calcium based sulfur sorbent is prepared in a highly reactive form for use in removing gaseous sulfur species from coal combustion gases by heating finely divided limestone particles at a temperature of at least 2,000 K for a period of 5 to 50 millisecond...

J. S. Abichandan N. T. Holcombe A. F. Litka J. A. Woodroffe

1991-01-01

211

Gene and Enhancer Trap Transposable Elements Reveal Oxygen Deprivation regulated Genes and their Complex Patterns of Expression in Arabidopsis  

Microsoft Academic Search

Transposon tagging with modified maize Ds-GUS constructs was used to isolate genes induced by oxygen deprivation in Arabidopsis thaliana. Seedlings of 800 gene-trap (DsG) and 600 enhancer-trap (DsE) lines were grown on vertically positioned plates for 1 week, oxygen deprived for up to 24 h and stained for GUS activity. Oxygen deprivation induced intricate patterns of gene expression in seedlings

AIRICA B AXTER-BURRELL; R UTH C HANG; S PRINGER; JULIA B AILEY-SERRES

2003-01-01

212

Enhanced proliferation of human skeletal muscle precursor cells derived from elderly donors cultured in estimated physiological (5%) oxygen  

Microsoft Academic Search

Human skeletal muscle precursor cells (myoblasts) have significant therapeutic potential and are a valuable research tool\\u000a to study muscle cell biology. Oxygen is a critical factor in the successful culture of myoblasts with low (1–6%) oxygen culture\\u000a conditions enhancing the proliferation, differentiation, and\\/or viability of mouse, rat, and bovine myoblasts. The specific\\u000a effects of low oxygen depend on the myoblast

Sheree D. Martin; Fiona M. Collier; Mark A. Kirkland; Ken Walder; Nicole Stupka

2009-01-01

213

The use of thermal analysis techniques to obtain information relevant to the in-situ combustion process for enhanced oil recovery  

Microsoft Academic Search

Thein-situ combustion technique of enhanced oil recovery may be used for the recovery of heavy oil deposits. In order to predict when\\u000a this process may be used computer-based simulators are being developed. The data required by these simulators are currently\\u000a available from two sources: (i) combustion tubes; these are complex, expensive and time consuming to run; (ii) thermal analysis\\u000a techniques;

A. Millington; D. Price; R. Hughes

1993-01-01

214

The role of the diffusion of oxygen and radiation on the spontaneous combustibility of a coal pile in confined storage  

Microsoft Academic Search

This paper deals with the spontaneous combustibility and ignition behavior of coal stored in confined spaces. The geometry, which views the stockpile to be sealed from all sides except the top (which is exposed to the ambient conditions), is of interest in the transport of coals in barges or in cars by rail. Semi-analytical solutions are developed with the assumption

Ashley S. Hull; Jennifer L. Lanthier; Zumao Chen; Pradeep K. Agarwal

1997-01-01

215

Overhauser enhanced magnetic resonance imaging for tumor oximetry: Coregistration of tumor anatomy and tissue oxygen concentration  

PubMed Central

An efficient noninvasive method for in vivo imaging of tumor oxygenation by using a low-field magnetic resonance scanner and a paramagnetic contrast agent is described. The methodology is based on Overhauser enhanced magnetic resonance imaging (OMRI), a functional imaging technique. OMRI experiments were performed on tumor-bearing mice (squamous cell carcinoma) by i.v. administration of the contrast agent Oxo63 (a highly derivatized triarylmethyl radical) at nontoxic doses in the range of 2–7 mmol/kg either as a bolus or as a continuous infusion. Spatially resolved pO2 (oxygen concentration) images from OMRI experiments of tumor-bearing mice exhibited heterogeneous oxygenation profiles and revealed regions of hypoxia in tumors (<10 mmHg; 1 mmHg = 133 Pa). Oxygenation of tumors was enhanced on carbogen (95% O2/5% CO2) inhalation. The pO2 measurements from OMRI were found to be in agreement with those obtained by independent polarographic measurements using a pO2 Eppendorf electrode. This work illustrates that anatomically coregistered pO2 maps of tumors can be readily obtained by combining the good anatomical resolution of water proton-based MRI, and the superior pO2 sensitivity of EPR. OMRI affords the opportunity to perform noninvasive and repeated pO2 measurements of the same animal with useful spatial (?1 mm) and temporal (2 min) resolution, making this method a powerful imaging modality for small animal research to understand tumor physiology and potentially for human applications.

Krishna, Murali C.; English, Sean; Yamada, Kenichi; Yoo, John; Murugesan, Ramachandran; Devasahayam, Nallathamby; Cook, John A.; Golman, Klaes; Ardenkjaer-Larsen, Jan Henrik; Subramanian, Sankaran; Mitchell, James B.

2002-01-01

216

Enhanced Formation of Oxidants from Bimetallic Nickel-Iron Nanoparticles in the Presence of Oxygen  

PubMed Central

Nanoparticulate zero-valent iron (nZVI) rapidly reacts with oxygen to produce strong oxidants, capable of transforming organic contaminants in water. However, the low yield of oxidants with respect to the iron added normally limits the application of this system. Bimetallic nickel-iron nanoparticles (nNi-Fe; i.e., Ni-Fe alloy and Ni-coated Fe nanoparticles) exhibited enhanced yields of oxidants compared to nZVI. nNi-Fe (Ni-Fe alloy nanoparticles with [Ni]/[Fe] = 0.28 and Ni-coated Fe nanoparticles with [Ni]/[Fe] = 0.035) produced approximately 40% and 85% higher yields of formaldehyde from the oxidation of methanol relative to nZVI at pH 4 and 7, respectively. Ni-coated Fe nanoparticles showed a higher efficiency for oxidant production relative to Ni-Fe alloy nanoparticles based on Ni content. Addition of Ni did not enhance the oxidation of 2-propanol or benzoic acid, indicating that Ni addition did not enhance hydroxyl radical formation. The enhancement in oxidant yield was observed over a pH range of 4 – 9. The enhanced production of oxidant by nNi-Fe appears to be attributable to two factors. First, the nNi-Fe surface is less reactive toward hydrogen peroxide (H2O2) than the nZVI surface, which favors the reaction of H2O2 with dissolved Fe(II) (the Fenton reaction). Second, the nNi-Fe surface promotes oxidant production from the oxidation of ferrous ion by oxygen at neutral pH values.

Lee, Changha; Sedlak, David L.

2009-01-01

217

Enhanced Surgical Imaging: Laparoscopic Vessel Identification and Assessment of Tissue Oxygenation  

PubMed Central

Background Inherent to minimally invasive procedures are loss of tactile feedback and loss of three dimensional assessment. Tasks such as vessel identification and dissection are not trivial for the inexperienced laparoscopic surgeon. Advanced surgical imaging, such as 3-CCD (charge-coupled device) image enhancement, can be used to assist with these more challenging tasks and, in addition, offers a method to non-invasively monitor tissue oxygenation during surgery. Study Design In this study, 3-CCD image enhancement is used for the identification of vessels in 25 laparoscopic donor and partial nephrectomy cases. The algorithm is then applied to two laparoscopic nephrectomy cases involving multiple renal arteries. We also utilize the 3-CCD camera to qualitatively monitor renal parenchymal oxygenation during 10 laparoscopic donor nephrectomies (LDNs). Results The mean ROI (region of interest) intensity values obtained for the renal artery and vein (68.40 ± 8.44 and 45.96 ± 8.65, respectively) are used to calculate a threshold intensity value (59.00) that allows for objective vessel differentiation. In addition, we examined the renal parenchyma during LDNs. Mean ROI intensity values were calculated for the renal parenchyma at two distinct time points, prior to vessel stapling (non-ischemic) and just before extraction from the abdomen (ischemic). The non-ischemic mean ROI intensity values are statistically different from the ischemic mean ROI intensity values (p < 0.05), even with short ischemia times. Conclusions We have developed a technique, 3-CCD image enhancement, for the identification of vasculature and for the monitoring of parenchymal oxygenation. This technique requires no additional laparoscopic operating room equipment and has real-time video capability.

Crane, Nicole J.; McHone, Ben; Hawksworth, Jason; Pearl, Jonathan P.; Denobile, John; Tadaki, Doug; Pinto, Peter A.; Levin, Ira W.; Elster, Eric A.

2009-01-01

218

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

219

A numerical simulation of shock-enhanced mixing in supersonic combustion  

Microsoft Academic Search

The development of supersonic combustion engines requires the ability to control fuel\\/air mixing with supersonic shear layers. The qualitative effect of an oblique shock impinging on a reacting shear layer of this type is examined. The Total Variation Diminishing (TVD) scheme is used in a Beam Warming approximate factorization numerical algorithm to solve the 2-D Navier-Stokes (N-S) equations and the

Domel

1990-01-01

220

Reversed flow fluidized-bed combustion apparatus  

DOEpatents

The present invention is directed to a fluidized-bed combustion apparatus provided with a U-shaped combustion zone. A cyclone is disposed in the combustion zone for recycling solid particulate material. The combustion zone configuration and the recycling feature provide relatively long residence times and low freeboard heights to maximize combustion of combustible material, reduce nitrogen oxides, and enhance sulfur oxide reduction.

Shang, Jer-Yu (Fairfax, VA); Mei, Joseph S. (Morgantown, WV); Wilson, John S. (Morgantown, WV)

1984-01-01

221

Enhanced formation of oxidants from bimetallic nickel-iron nanoparticles in the presence of oxygen.  

PubMed

Nanoparticulate zero-valent iron (nZVI) rapidly reacts with oxygen to produce strong oxidants capable of transforming organic contaminants in water. However,the low yield of oxidants with respect to the iron added normally limits the application of this system. Bimetallic nickel-iron nanoparticles (nNi-Fe; i.e., Ni-Fe alloy and Ni-coated Fe nanoparticles) exhibited enhanced yields of oxidants compared to nZVI. nNi-Fe (Ni-Fe alloy nanoparticles with [Ni]/[Fe] = 0.28 and Ni-coated Fe nanoparticles with [Ni]/[Fe] = 0.035) produced approximately 40% and 85% higher yields of formaldehyde from the oxidation of methanol relative to nZVI at pH 4 and 7, respectively. Ni-coated Fe nanoparticles showed a higher efficiency for oxidant production relative to Ni-Fe alloy nanoparticles based on Ni content. Addition of Ni did not increase the oxidation of 2-propanol or benzoic acid, indicating that Ni addition did not enhance hydroxyl radical formation. The enhancement in oxidant yield was observed over a pH range of 4-9. The enhanced production of oxidant by nNi-Fe appears to be attributable to two factors. First, the nNi-Fe surface is less reactive toward hydrogen peroxide (H2O2) than the nZVI surface, which favors the reaction of H2O2 with dissolved Fe(II) (the Fenton reaction). Second, the nNi-Fe surface promotes oxidant production from the oxidation of ferrous ion by oxygen at neutral pH values. PMID:19068843

Lee, Changha; Sedlak, David L

2008-11-15

222

Shell-anchor-core structures for enhanced stability and catalytic oxygen reduction activity  

NASA Astrophysics Data System (ADS)

Density functional theory is used to evaluate activity and stability properties of shell-anchor-core structures. The structures consist of a Pt surface monolayer and a composite core having an anchor bilayer where C atoms in the interstitial sites lock 3d metals in their locations, thus avoiding their surface segregation and posterior dissolution. The modified subsurface geometry induces less strain on the top surface, thus exerting a favorable effect on the surface catalytic activity where the adsorption strength of the oxygenated species becomes more moderate: weaker than on pure Pt(111) but stronger than on a Pt monolayer having a 3d metal subsurface. Here we analyze the effect of changing the nature of the 3d metal in the subsurface anchor bilayer, and we also test the use of a Pd monolayer instead of Pt on the surface. It is found that a subsurface constituted by two layers with an approximate composition of M2C (M=Fe, Ni, and Co) provides a barrier for the migration of subsurface core metal atoms to the surface. Consequently, an enhanced resistance against dissolution in parallel to improved oxygen reduction activity is expected, as given by the values of adsorption energies of reaction intermediates, delayed onset of water oxidation, and/or low coverage of oxygenated species at surface oxidation potentials.

Ramirez-Caballero, Gustavo E.; Hirunsit, Pussana; Balbuena, Perla B.

2010-10-01

223

Analysis of Acid Gas Emissions in the Combustion of the Binder Enhanced D-Rdf by Ion Chromatography.  

NASA Astrophysics Data System (ADS)

Waste-to-energy has become an attractive alternative to landfills. One concern in this development is the release of pollutants in the combustion process. The binder enhanced d-RDF pellets satisfy the requirements of environmental acceptance, chemical/biological stability, and being storeable. The acid gas emissions of combusting d-RDF pellets with sulfur -rich coal were analyzed by ion chromatography and decreased when d-RDF pellets were utilized. The results imply the possibility of using d-RDF pellets to substitute for sulfur -rich coal as fuel, and also substantiate the effectiveness of a binder, calcium hydroxide, in decreasing emissions of SOx. In order to perform the analysis of the combustion sample, sampling and sample pretreatment methods prior to the IC analysis and the first derivative detection mode in IC are investigated as well. At least two trapping reagents are necessary for collecting acid gases: one for hydrogen halides, and the other for NOx and SOx. Factors affecting the absorption of acid gases are studied, and the strength of an oxidizing agent is the main factor affecting the collection of NOx and SOx. The absorption preference series of acid gases are determined and the absorption models of acid gases in trapping reagents are derived from the analytical results. To prevent the back-flushing of trapping reagents between impingers when leak-checking, a design for the sampling train is suggested, which can be adopted in sample collections. Several reducing agents are studied for pretreating the sample collected in alkali -permanganate media. Besides the recommendation of the hydrogen peroxide solution in EPA method, methanol and formic acid are worth considering as alternate reducing agents in the pretreatment of alkaline-permanganate media prior to IC analysis. The first derivative conductivity detection mode is developed and used in IC system. It is efficient for the detection and quantification of overlapping peaks as well as being applicable for nonoverlapping peaks.

Jen, Jen-Fon

1988-12-01

224

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

225

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

226

Oxygen Reduction Kinetics Enhancement on a 2 Heterostructured Oxide Surface for Solid Oxide Fuel Cells  

SciTech Connect

Heterostructured interfaces of oxides, which can exhibit transport and reactivity characteristics remarkably different from those of bulk oxides, are interesting systems to explore in search of highly active cathodes for the oxygen reduction reaction (ORR). Here, we show that the ORR of {approx}85 nm thick La{sub 0.8}Sr{sub 0.2}CoO{sub 3-{delta}} (LSC{sub 113}) films prepared by pulsed laser deposition on (001)-oriented yttria-stabilized zirconia (YSZ) substrates is dramatically enhanced ({approx} 3-4 orders of magnitude above bulk LSC{sub 113}) by surface decorations of (La{sub 0.5}Sr{sub 0.5}){sub 2}CoO{sub 4{+-}{delta}} (LSC{sub 214}) with coverage in the range from {approx}0.1 to {approx}15 nm. Their surface and atomic structures were characterized by atomic force, scanning electron, and scanning transmission electron microscopy, and the ORR kinetics were determined by electrochemical impedance spectroscopy. Although the mechanism for ORR enhancement is not yet fully understood, our results to date show that the observed ORR enhancement can be attributed to highly active interfacial LSC{sub 113}/LSC{sub 214} regions, which were shown to be atomically sharp.

Crumlin, Ethan [Massachusetts Institute of Technology (MIT); Mutoro, Eva [ORNL; Ahn, Sung Jin [Massachusetts Institute of Technology (MIT); Jose la O', Gerardo [Massachusetts Institute of Technology (MIT); Leonard, Donovan N [ORNL; Borisevich, Albina Y [ORNL; Biegalski, Michael D [ORNL; Christen, Hans M [ORNL; Shao-Horn, Yang [Massachusetts Institute of Technology (MIT)

2010-01-01

227

Internal combustion engine  

Microsoft Academic Search

An improvement to an internal combustion engine is disclosed that has a fuel system for feeding a fuel-air mixture to the combustion chambers and an electrical generation system, such as an alternator. An electrolytic cell is attached adjacent to the engine to generate hydrogen and oxygen upon the application of a voltage between the cathode and anode of the electrolytic

Valdespino

1981-01-01

228

Enhanced decomposition of dimethyl phthalate via molecular oxygen activated by Fe@Fe2O3/AC under microwave irradiation.  

PubMed

In this study, we demonstrate that the decomposition of dimethyl phthalate under microwave irradiation could be greatly enhanced over Fe@Fe(2)O(3) nanowires supported on activated carbon (Fe@Fe(2)O(3)/AC). The great enhanced decomposition of dimethyl phthalate could be attributed to a unique microwave induced molecular oxygen activation process. Upon microwave irradiation, electrons could be transferred from activated carbon to zero-valent iron, and then react with molecular oxygen to form O(2)(-) and OH radicals for the decomposition of dimethyl phthalate. The deactivation and the regeneration of Fe@Fe(2)O(3)/AC catalyst were systematically studied. We also found that microwave heating could accelerate the electron transferring from AC to Fe@Fe(2)O(3) to generate more reactive oxygen species for the decomposition of DMP than conventional oil bath heating. This novel molecular oxygen activation approach may find applications for wastewater treatment and drinking water purification. PMID:22883705

Chen, Yiling; Ai, Zhihui; Zhang, Lizhi

2012-07-24

229

Oxygen Ion Implantation Enhanced Silicon-Vacancy Photoluminescence and n-Type Conductivity of Ultrananocrystalline Diamond Films  

NASA Astrophysics Data System (ADS)

We report the enhanced silicon-vacancy (Si-V) photoluminescence (PL) intensity and n-type conductivity of ultrananocrystalline diamond (UNCD) films by oxygen ion (O+) implantation. With O+ dose increasing from 1014 to 1015 cm-2, the PL intensity and n-type conductivity significantly increase by 6 and 45 times, respectively, after 1000°C annealing. The secondary ion mass spectroscopy mapping measurements show that the content of oxygen is larger in the zone, which has larger content of silicon, indicating that oxygen tends to adhere to silicon. It is suggested that oxygen related Si-V defects are formed, which will enhance the PL intensity and n-type conductivity of UNCD films.

Hu, Xiao-Jun; Li, Nian

2013-08-01

230

Inhibition of Histone Deacetylase Activity in Reduced Oxygen Environment Enhances the Osteogenesis of Mouse Adipose-Derived Stromal Cells  

PubMed Central

Recent studies suggest that oxygen tension has a great impact on the osteogenic differentiation capacity of mesenchymal cells derived from adipose tissue: reduced oxygen impedes osteogenesis. We have found that expansion of mouse adipose-derived stromal cells (mASCs) in reduced oxygen tension (10%) results in increased cell proliferation along with induction of histone deacetylase (HDAC) activity. In this study, we utilized two HDAC inhibitors (HDACi), sodium butyrate (NaB) and valproic acid (VPA), and studied their effects on mASCs expanded in various oxygen tensions (21%, 10%, and 1% O2). Significant growth inhibition was observed with NaB or VPA treatment in each oxygen tension. Osteogenesis was enhanced by treatment with NaB or VPA, particularly in reduced oxygen tensions (10% and 1% O2). Conversely, adipogenesis was decreased with treatments of NaB or VPA at all oxygen tensions. Finally, NaB- or VPA-treated, reduced oxygen tension–exposed (1% O2) ASCs were grafted into surgically created mouse tibial defects and resulted in significantly increased bone regeneration. In conclusion, HDACi significantly promote the osteogenic differentiation of mASCs exposed to reduced oxygen tension; HDACi may hold promise for future clinical applications of ASCs for skeletal regeneration.

Xu, Yue; Hammerick, Kyle E.; James, Aaron W.; Carre, Antoine L.; Leucht, Philipp; Giaccia, Amato J.

2009-01-01

231

Catalytic Activity Enhancement for Oxygen Reduction on Epitaxial Perovskite Thin Films for Solid-Oxide Fuel Cells  

SciTech Connect

The active ingredient: La{sub 0.8}Sr{sub 0.2}CoO{sub 3-{delta}} (LSC) epitaxial thin films are prepared on (001)-oriented yttria-stabilized zirconia (YSZ) single crystals with a gadolinium-doped ceria (GDC) buffer layer. The LSC epitaxial films exhibit better oxygen reduction kinetics than bulk LSC. The enhanced activity is attributed in part to higher oxygen nonstoichiometry.

La O', Gerardo Jose [Massachusetts Institute of Technology (MIT); Ahn, Sung Jin [Massachusetts Institute of Technology (MIT); Crumlin, Ethan [Massachusetts Institute of Technology (MIT); Orikasa, Yuki [Massachusetts Institute of Technology (MIT); Biegalski, Michael D [ORNL; Christen, Hans M [ORNL; Shao-Horn, Yang [Massachusetts Institute of Technology (MIT)

2010-01-01

232

Role of Metal Coordination Structures in Enhancement of Electrocatalytic Activity of Ternary Nanoalloys for Oxygen Reduction Reaction  

SciTech Connect

The ability to harness the metal-metal and metal-oxygen coordination structures of nanoalloy catalysts is critical for catalyzing the oxygen reduction reaction because such a detailed atomic-scale structure dictates the surface binding site and strength for molecular oxygen and oxygenated intermediate species in the electrocatalytic process. This report describes the results of an investigation of the metal-metal and metal-oxygen coordination structures of ternary nanoalloys and their manipulation to enhance the electrocatalytic activity for oxygen reduction reaction. The basic hypothesis is that such atomic-scale structure can be manipulated by oxidative-reductive thermal treatment to influence the binding site and strength of molecular oxygen and oxygenated species on the nanoalloy surface. The results have revealed remarkable increases in both mass activity and specific activity for the catalysts processed by the oxidative-reductive treatment over those treated under non-reactive or low-degree oxidative atmospheres before the reductive treatment. In comparison with non-reactive-reductive treatment, an increased degree of heteroatomic alloying among the three metal components in the ternary catalysts and a decreased percentage of oxides (NiO and CoO) have been revealed by X-ray absorption fine structure spectroscopy for the catalysts treated by the oxidative-reductive treatment. An enrichment of surface Pt has also been detected by x-ray photoelectron spectroscopy for such catalysts. A combination of the increase in the heteroatomic alloying, the decrease in metal oxides, and the enrichment of surface Pt by the oxidative-reductive thermal treatment has therefore been concluded to be responsible for the enhanced electrocatalytic activity. The demonstration of this new approach to manipulating the metal-metal and metal-oxygen coordination structures forms the basis for an effective strategy in engineering ternary nanoalloy catalysts, and has provided new insights into the role of such structures in the enhancement of the electrocatalytic activity.

Wanjala, Bridgid N.; Fang, Bin; Loukrakpam, Rameshwori; Chen, Yongsheng; Engelhard, Mark H.; Luo, Jin; Yin, Jun; Yang, Lefu; Shan, Shiyao; Zhong, Chuan-Jian

2012-04-04

233

Including oxygen enhancement ratio in ion beam treatment planning: model implementation and experimental verification  

NASA Astrophysics Data System (ADS)

We present a method for adapting a biologically optimized treatment planning for particle beams to a spatially inhomogeneous tumor sensitivity due to hypoxia, and detected e.g., by PET functional imaging. The TRiP98 code, established treatment planning system for particles, has been extended for including explicitly the oxygen enhancement ratio (OER) in the biological effect calculation, providing the first set up of a dedicated ion beam treatment planning approach directed to hypoxic tumors, TRiP-OER, here reported together with experimental tests. A simple semi-empirical model for calculating the OER as a function of oxygen concentration and dose averaged linear energy transfer, generating input tables for the program is introduced. The code is then extended in order to import such tables coming from the present or alternative models, accordingly and to perform forward and inverse planning, i.e., predicting the survival response of differently oxygenated areas as well as optimizing the required dose for restoring a uniform survival effect in the whole irradiated target. The multiple field optimization results show how the program selects the best beam components for treating the hypoxic regions. The calculations performed for different ions, provide indications for the possible clinical advantages of a multi-ion treatment. Finally the predictivity of the code is tested through dedicated cell culture experiments on extended targets irradiation using specially designed hypoxic chambers, providing a qualitative agreement, despite some limits in full survival calculations arising from the RBE assessment. The comparison of the predictions resulting by using different model tables are also reported.

Scifoni, E.; Tinganelli, W.; Weyrather, W. K.; Durante, M.; Maier, A.; Krämer, M.

2013-06-01

234

Enhanced removal of carbon dioxide and alleviation of dissolved oxygen accumulation in photobioreactor with bubble tank.  

PubMed

Reduction of carbon loss from the effluent is one of the most important aspects of photobioreactors design. In this study, a novel gas sparger of bubble tank was adopted in a photobioreactor to enhance carbon dioxide (CO(2)) mass transfer rate as well as alleviate dissolved oxygen (DO) accumulation. The results showed that low DO level in the culture can be obtained due to the turbulent hydrodynamic condition provided by the bubble tank. The effects of CO(2) concentration, flow rate of influent, and light intensity on CO(2) removal efficiency were investigated. The maximum CO(2) removal efficiency was 94% at flow rate of 30 mL min(-1), light intensity of 179 ?mol m(-2) s(-1) and CO(2) concentration of 10%, implying that the novel gas sparger is a promising alternative for CO(2) removal from CO(2)-enriched air by cultivating microalgae in the photobioreactor. PMID:22531167

Chai, Xiaoli; Zhao, Xin

2012-04-05

235

Recombination-enhanced formation of the metastable boron-oxygen complex in crystalline silicon  

NASA Astrophysics Data System (ADS)

The formation process of the boron- and oxygen-related defect complex in crystalline silicon, responsible for the performance degradation of solar cells made on boron-doped Czochralski silicon (Cz-Si), is investigated on Cz-Si solar cells as a function of the applied voltage in the dark at temperatures ranging from 298 to 373 K. We show that the defect formation is not only a consequence of illumination or the application of a forward bias voltage but also occurs under equilibrium conditions at elevated temperatures in the dark. It can be partly suppressed by applying a reverse voltage. Our findings provide clear experimental evidence that a recombination-enhanced mechanism correlated with the total recombination rate is the driving force of the formation of the metastable defect.

Bothe, Karsten; Hezel, Rudolf; Schmidt, Jan

2003-08-01

236

Durability enhancement and degradation of oxygen evolution anodes in seawater electrolysis for hydrogen production  

NASA Astrophysics Data System (ADS)

For the anode composed of electrocatalyst oxide, intermediate layer and titanium substrate, the substitution of a certain amount of iridium with tin in the IrO 2 intermediate layer was remarkably effective in elongating the life of the anode in preventing oxidation of the substrate titanium during oxygen evolution. The longest life was realized by preparation of intermediate layer with uniform thickness by brush-coating of H 2IrCl 6-SnCl 4 butanol solution and subsequent calcination. The anode with the intermediate layer prepared from 0.04 M H 2IrCl 6-0.06 M SnCl 4 butanol solution showed the best performance, that is, the oxygen evolution efficiency higher than 99.8% for more than 4300 h in the electrolysis of 0.5 M NaCl solution of pH 1 at the current density of 1000 Am -2. An increase in SnCl 4 concentration decreased the viscosity of the coating solution with a consequent enhancement of uniformity of the intermediate layer but decreased the thickness of the intermediate layer acting as a barrier to prevent oxidation of titanium. Thus, the best performance was attained at an intermediate SnCl 4 concentration. The growth of an oxide layer on titanium during electrolysis occurred and was found by the potential increase.

Kato, Zenta; Bhattarai, Jagadeesh; Kumagai, Naokazu; Izumiya, Koichi; Hashimoto, Koji

2011-07-01

237

Controlled synthesis of Pd-Pt alloy hollow nanostructures with enhanced catalytic activities for oxygen reduction.  

PubMed

Pd-Pt alloy nanocrystals (NCs) with hollow structures such as nanocages with porous walls and dendritic hollow structures and Pd@Pt core-shell dendritic NCs could be selectively synthesized by a galvanic replacement method with uniform Pd octahedral and cubic NCs as sacrificial templates. Fine control over the degree of galvanic replacement of Pd with Pt allowed the production of Pd-Pt NCs with distinctly different morphologies. The synthesized hollow NCs exhibited considerably enhanced oxygen reduction activities compared to those of Pd@Pt core-shell NCs and a commercial Pt/C catalyst, and their electrocatalytic activities were highly dependent on their morphologies. The Pd-Pt nanocages prepared from octahedral Pd NC templates exhibited the largest improvement in catalytic performance. We expect that the present work will provide a promising strategy for the development of efficient oxygen reduction electrocatalysts and can also be extended to the preparation of other hybrid or hetero-nanostructures with desirable morphologies and functions. PMID:22360814

Hong, Jong Wook; Kang, Shin Wook; Choi, Bu-Seo; Kim, Dongheun; Lee, Sang Bok; Han, Sang Woo

2012-02-29

238

Advanced glycation end products enhance reactive oxygen and nitrogen species generation in neutrophils in vitro.  

PubMed

Increased oxidative stress (OS) in diabetes mellitus is one of the major factors leading to diabetic pathology. However, the mediators and mechanism that provoke OS in diabetes is not fully understood, and it is possible that accumulation of advanced glycation end products (AGEs) formed secondary to hyperglycemic conditions may incite circulating polymorphonuclear neutrophils (PMN) to generate reactive oxygen species (ROS). In this report, we aim to investigate the effect of AGE on reactive oxygen and nitrogen species generation and subsequent OS in PMN. AGE-HSA exert dose- and time-dependent enhancement of ROS and reactive nitrogen intermediates (RNI) generation by PMN. Increased ROS and RNI generation were found to be mediated through the upregulation of NADPH oxidase and inducible nitric oxide synthase (iNOS), respectively, as evident from the fact that AGE-treated neutrophils failed to generate ROS and RNI in presence of diphenyleneiodonium, a flavoprotein inhibitor for both enzymes. Further increased generation of ROS and RNI ceased when the cells were incubated with anti-RAGE antibody suggesting the involvement of AGE-RAGE interaction. Also increased malondialdehyde (MDA) and protein carbonyl formation in AGE-exposed PMN suggest induction of OS by AGE. This study provides evidence that AGEs may play a key role in the induction of oxidative stress through the augmentation of PMN-mediated ROS and RNI generation and this may be in part responsible for development of AGE-induced diabetic pathology. PMID:22048812

Bansal, Savita; Siddarth, Manushi; Chawla, Diwesh; Banerjee, Basu D; Madhu, S V; Tripathi, Ashok K

2011-11-03

239

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

240

Photoprocesses in diphenylpolyenes. Oxygen and heavy-atom enhancement of triplet yeilds  

SciTech Connect

Results, obtained by nanosecond laser flash photolysis (337.1 nm) and fluorescence measurements, are presented concerning triplet-triplet spectra and excited-state dynamics of three all-trans ..cap alpha..,..omega..-diphenyl-substituted polyenes, Ph(CH=CH)/sub n/Ph (n = 2-4), in various solvents and in the presence of oxygen and heavy-atom-containing molecules. The spectra of triplets generated by both direct excitation and energy transfer, display the characteristics of an intense Franck-Condon allowed transition with vibrational spacings in the range 1200-1600 cm/sup -1/ and show solvent-effect and chain-length dependence very similar to those observed for the strongly allowed band system in ground-state absorption. The quantum yields of occupation of lowest triplet are small (0.5-3%) in deaerated solvents such as cyclohexane, methanol, and benzene, but become significantly enhanced in heavy-atom-containing solvents (e.g., ethyl bromide and bromobenzene) and in the presence of oxygen and heavy-atom species. The intersystem crossing rate constants for T/sub 1/reverse arrowS/sub 1/ and S/sub 0/reverse arrowT/sub 1/ are in the ranges 7 x 10/sup 5/ - 9 x 10/sup 7/ and 2 x 10/sup 4/ - 7 x 10/sup 5/ s/sup -1/, respectively, and exhibit a decreasing trend as the polyene chain length is increased. Based on kinetic data concerning singlet quenching and triplet yield enhancement by O/sub 2/ and ethyl iodide in methanol and cyclohexane, the fraction of the singlet quenching events that result in triplet generation is found to range from 0.1 to 0.8. The correlation (or lack of it) between intersystem crossing rate constants and those for bimolecular quenching of singlet and triplet is discussed in the context of the energy gap law observed in similar studies for aromatic hydrocarbons.

Chattopadhyay, S.K. (Univ. of Notre Dame, IN); Das, P.K.; Hug, G.L.

1982-08-25

241

Acute reduction in oxygen tension enhances the induction of neurons from human fibroblasts.  

PubMed

We and others have reported the successful conversion of human fibroblasts into functional induced neuronal (iN) cells; however the reprogramming efficiencies were very low. Robust reprogramming methods must be developed before iN cells can be used for translational applications such as disease modeling or transplantation-based therapies. Here, we describe a novel approach in which we significantly enhance iN cell conversion efficiency of human fibroblast cells by reprogramming under hypoxic conditions (5% O?). Fibroblasts were derived under high (21%) or low (5%) oxygen conditions and reprogrammed into iN cells using a combination of the four transcription factors BRN2, ASCL1, MYT1L and NEUROD1. An increase in Map2 immunostaining was only observed when fibroblasts experienced an acute drop in O? tension upon infection. Interestingly, cells derived and reprogrammed under hypoxic conditions did not produce more iN cells. Approximately 100% of patched cells fired action potentials in low O? conditions compared to 50% under high O? growth conditions, confirming the beneficial aspect of reprogramming under low O?. Further characterization showed no significant difference in the intrinsic properties of iN cells reprogrammed in either condition. Surprisingly, the acute drop in oxygen tension did not affect cell proliferation or cell survival and was not synergistic with the blockade of GSK3? and Smad-mediated pathways. Our results showed that lowering the O? tension at the initiation of reprogramming is a simple and efficient strategy to enhance the production of iN cells which will facilitate their use for basic discovery and regenerative medicine. PMID:23562599

Davila, Jonathan; Chanda, Soham; Ang, Cheen Euong; Südhof, Thomas C; Wernig, Marius

2013-04-03

242

Oxygen gas concentration-detecting apparatus and air-fuel ratio-controlling apparatus using same in internal combustion engine  

SciTech Connect

An oxygen concentration-detecting apparatus is described comprising a ceramic substrate for generating an electromotive force between a first surface contacted with a reference gas and a second surface contacted with a gas to be detected according to the ratio of the concentration of oxygen gas O/sub 2/ between the two gases, a pair of electrode members formed at parts of the first and second surfaces, respectively, of the ceramic substrate, to take out the electromotive force as a detection signal, an oxidation catalyst layer arranged to cover the outer surface of the ceramic substrate and promote oxidation reaction of unburnt components, and a reduction catalyst layer arranged to cover an outer surface of the ceramic substrate and promote mainly reduction reaction of nitrogen oxides NO/sub x/.

Uchikawa, A.; Anbe, S.; Suwa, T.; Kawashima, M.; Yamada, T.

1988-09-27

243

Oxygen-enhanced IrMn spin valves deposited by ion-beam and magnetron sputtering  

SciTech Connect

Enhancement of giant magnetoresistance properties of single (bottom) and dual IrMn-based spin valves through exposure of part of the CoFe pinned layer to O{sub 2} is reported. Under optimal conditions, a {Delta}R/R of 10.4% [H{sub ua}=460Oe, H{sub f}=5.1Oe, and H{sub c}=4.7Oe for a free and pinned layer thickness (permalloy equivalent) of 50 Aa each] for an ion beam sputtered single spin valve, and a {Delta}R/R of as high as 20.5% for a magnetron sputtered dual spin valve having a 30 Aa thick CoFe free layer are observed, compared to a value of 6.5% and 10.6% for the corresponding spin valve without O{sub 2} exposure, respectively. Transmission electron microscopy results reveal the presence of a thin (10 Aa) crystalline oxygen-containing layer near the IrMn{endash}CoFe pinned layer interface as a result of O{sub 2} exposure. X-ray reflectivity data show smoother interfaces for the spin valves subjected to O{sub 2} exposure, consistent with the lower H{sub f} and smaller sheet resistance observed for these samples. The enhanced {Delta}R/R thus can be attributed to improved growth after O{sub 2} exposure. {copyright} 2001 American Institute of Physics.

Lee, W. Y.; Carey, M.; Toney, M. F.; Rice, P.; Gurney, B.; Chang, H.-C.; Allen, E.; Mauri, D.

2001-06-01

244

Colloidal gold nanorings for improved photodynamic therapy through field-enhanced generation of reactive oxygen species  

NASA Astrophysics Data System (ADS)

Au nanostructures that exhibit strong localized surface plasmon resonance (SPR) have excellent potential for photo-medicine, among a host of other applications. Here, we report the synthesis and use of colloidal gold nanorings (GNRs) with potential for enhanced photodynamic therapy of cancer. The GNRs were fabricated via galvanic replacement reaction of sacrificial Co nanoparticles in gold salt solution with low molecular weight (Mw = 2,500) poly(vinylpyrrolidone) (PVP) as a stabilizing agent. The size and the opening of the GNRs were controlled by the size of the starting Co particles and the concentration of the gold salt. UV-Vis absorption measurements indicated the tunability of the SPR of the GNRs from 560 nm to 780 nm. MTT assay showed that GNRs were non-toxic and biocompatible when incubated with breast cancer cells as well as the healthy counterpart cells. GNRs conjugated with 5-aminolevulinic acid (5-ALA) photosensitizer precursor led to elevated formation of reactive oxygen species and improved efficacy of photodynamic therapy of breast cancer cells under light irradiation compared to 5-ALA alone. These results can be attributed to significantly enhance localized electromagnetic field of the GNRs.

Hu, Yue; Yang, Yamin; Wang, Hongjun; Du, Henry

2013-02-01

245

Mitochondrion-Derived Reactive Oxygen Species Lead to Enhanced Amyloid Beta Formation  

PubMed Central

Abstract Aims: Intracellular amyloid beta (A?) oligomers and extracellular A? plaques are key players in the progression of sporadic Alzheimer's disease (AD). Still, the molecular signals triggering A? production are largely unclear. We asked whether mitochondrion-derived reactive oxygen species (ROS) are sufficient to increase A? generation and thereby initiate a vicious cycle further impairing mitochondrial function. Results: Complex I and III dysfunction was induced in a cell model using the respiratory inhibitors rotenone and antimycin, resulting in mitochondrial dysfunction and enhanced ROS levels. Both treatments lead to elevated levels of A?. Presence of an antioxidant rescued mitochondrial function and reduced formation of A?, demonstrating that the observed effects depended on ROS. Conversely, cells overproducing A? showed impairment of mitochondrial function such as comprised mitochondrial respiration, strongly altered morphology, and reduced intracellular mobility of mitochondria. Again, the capability of these cells to generate A? was partly reduced by an antioxidant, indicating that A? formation was also ROS dependent. Moreover, mice with a genetic defect in complex I, or AD mice treated with a complex I inhibitor, showed enhanced A? levels in vivo. Innovation: We show for the first time that mitochondrion-derived ROS are sufficient to trigger A? production in vitro and in vivo. Conclusion: Several lines of evidence show that mitochondrion-derived ROS result in enhanced amyloidogenic amyloid precursor protein processing, and that A? itself leads to mitochondrial dysfunction and increased ROS levels. We propose that starting from mitochondrial dysfunction a vicious cycle is triggered that contributes to the pathogenesis of sporadic AD. Antioxid. Redox Signal. 16, 1421–1433.

Schutt, Tanja; Kurz, Christopher; Eckert, Schamim H.; Schiller, Carola; Occhipinti, Angelo; Mai, Soren; Jendrach, Marina; Eckert, Gunter P.; Kruse, Shane E.; Palmiter, Richard D.; Brandt, Ulrich; Drose, Stephan; Wittig, Ilka; Willem, Michael; Haass, Christian; Reichert, Andreas S.; Muller, Walter E.

2012-01-01

246

Combustion of solid waste in a pulse incinerator  

NASA Astrophysics Data System (ADS)

This study investigated the effects of pulsations on the combustion of simulated solid waste at high Reynolds numbers in an incinerator fed with cold or preheated combustion air. Corrugated cardboard and charcoal were chosen as waste surrogates. Combustion times and emissions of CO2, CO and NOx were measured while the samples were burned under different experimental conditions. Pulsations significantly reduced flaming combustion times in tests with and without preheated. Most of this enhancement resulted from increased heat transfer rate due to a closer attachment of the gas flame to the solid sample. Pulsations also reduced smoldering combustion time. This was caused by faster transport of oxygen to and combustion products from the sample surface. Furthermore, the smoldering combustion rate increased with increasing Sound Pressure Levels. While this effect was the strongest in laminar flows, pulsations doubled combustion rates even in a highly turbulent flow where Re = 47,000. Higher combustion rates at elevated Reynolds numbers in steady tests were caused by larger turbulent velocity fluctuations. Combustion rates were further enhanced by the addition of acoustic velocity fluctuations, which dominated the process if they were much larger than the turbulent velocity fluctuations. Below this limit, acoustic modes with velocities normal to the main flow enhanced the combustion process more significantly than those parallel to the flow. Most of this enhancement by pulsations resulted from increased species transport due to faster removal of ash layers on the burning surface by acoustic shear. Acoustic streaming was not responsible for the observed, enhanced combustion rates. Instantaneous pollutant emissions were much higher with pulsations than without. However, pulsations did not affect total amount of carbon converted into gaseous products from the sample but favored more complete combustion, i.e., less total CO emission. This was caused by a larger fraction of the sample being burned by gas flame with pulsations. Total NOx emissions, on the other hand, were not affected by pulsations during smoldering but increased during flaming combustion. The later was caused by higher thermal NO x emission with pulsations.

Kan, Tie

247

The Influence of Gliomas and Nonglial Space-occupying Lesions on Blood-oxygen-level-dependent Contrast Enhancement  

Microsoft Academic Search

BACKGROUND AND PURPOSE: Functional MR (fMR) imaging with blood-oxygen-level- dependent (BOLD) contrast enhancement is increasingly used as a noninvasive tool for pre- surgical mapping in patients with intracranial tumors. Most physiologic studies of task-related BOLD contrast enhancement have involved healthy volunteers. Therefore, it is not known whether BOLD contrast is evoked in the same way in or adjacent to tumor

Axel Schreiber; Ulrich Hubbe; Sargon Ziyeh; Jurgen Hennig

2000-01-01

248

Smouldering Combustion Phenomena in Science and Technology  

Microsoft Academic Search

Smouldering is the slow, low-temperature, flameless form of combustion of a condensed fuel. It poses safety and environmental hazards and allows novel technological application but its fundamentals remain mostly unknown to the scientific community. The terms filtering combustion, smoking problem, deep seated fires, hidden fires, peat or peatlands fires, lagging fires, low oxygen combustion, in-situ combustion, fireflood and underground gasification,

Guillermo Rein

249

Enthalpies of Combustion and Formation of Some Alkyl Cyclopropanes.  

National Technical Information Service (NTIS)

The enthalpies of combustion of six alkyl cyclopropanes were measured by oxygen-bomb combustion calorimetry. Values are reported for the standard enthalpy of combustion of these compounds in the liquid state: methylcyclopropane, ethylcyclopropane, 1,cis-2...

W. D. Good

1971-01-01

250

The application of profluorescent nitroxides to detect reactive oxygen species derived from combustion-generated particulate matter: Cigarette smoke - A case study  

NASA Astrophysics Data System (ADS)

Reactive oxygen species (ROS) and related free radicals are considered to be key factors underpinning the various adverse health effects associated with exposure to ambient particulate matter. Therefore, measurement of ROS is a crucial factor for assessing the potential toxicity of particles. In this work, a novel profluorescent nitroxide, BPEAnit, was investigated as a probe for detecting particle-derived ROS. BPEAnit has a very low fluorescence emission due to inherent quenching by the nitroxide group, but upon radical trapping or redox activity, a strong fluorescence is observed. BPEAnit was tested for detection of ROS present in mainstream and sidestream cigarette smoke. In the case of mainstream cigarette smoke, there was a linear increase in fluorescence intensity with an increasing number of cigarette puffs, equivalent to an average of 101 nmol ROS per cigarette based on the number of moles of the probe reacted. Sidestream cigarette smoke sampled from an environmental chamber exposed BPEAnit to much lower concentrations of particles, but still resulted in a clearly detectible increase in fluorescence intensity with sampling time. It was calculated that the amount of ROS was equivalent to 50 ± 2 nmol per mg of particulate matter; however, this value decreased with ageing of the particles in the chamber. Overall, BPEAnit was shown to provide a sensitive response related to the oxidative capacity of the particulate matter. These findings present a good basis for employing the new BPEAnit probe for the investigation of particle-related ROS generated from cigarette smoke as well as from other combustion sources.

Miljevic, B.; Fairfull-Smith, K. E.; Bottle, S. E.; Ristovski, Z. D.

2010-06-01

251

Effect of nasal cannula oxygen administration on oxygen concentration at facial and adjacent landmarks.  

PubMed

An oxygen-enriched atmosphere enhances the potential for operating-room fires. We thus determined oxygen concentrations at various facial landmarks during oxygen administration via nasal cannulae. Thirteen supine volunteers were draped similarly to patients undergoing a cervical-node biopsy. Oxygen was delivered in random order through nasal cannulae at rates of 2, 4, and 6 l x min(-1). Oxygen concentration was measured at pre-determined facial landmarks and also distal to the drape at non-facial sites. At a flow of 2 l x min(-1), oxygen concentrations exceeded 23% only within a few centimetres of the nasal cannula. Concentration increased as a function of flow, but rarely exceeded 26%. At all flow rates, concentrations distal to the drape were < 24%. To reduce combustion risk, ignition sources should be kept at least 10 cm from the oxygen outlet when using nasal cannula at a flow rate > or = 4 l x min(-1). PMID:19413822

Orhan-Sungur, M; Komatsu, R; Sherman, A; Jones, L; Walsh, D; Sessler, D I

2009-05-01

252

Enhanced Oxygen Barrier and Interfacial Adhesion of Polystyrene/Clay Nanocomposites via Plasma Surface Modification  

NASA Astrophysics Data System (ADS)

Bentonite layered-silicate was the selected nanofiller to be studied and filled in polystyrene, consequently represented PS/clay nanocomposites. The plasma technique developed in our laboratory was utilized as the clay pretreatment method to provide the radical sites on the clay surface prior to styrene grafting step. Gas barrier property and impact strength, one of the most serious deficiencies of polystyrene, were examined. Oxygen permeability was found to be decreased moderately even small amount of modified clay loaded. As the result of plasma surface modification, it was found that grafting of styrene was occurred mainly on the outer clay layer since FT-IR spectra showed the characteristic peak of polystyrene with the same basel-spacing like pristine clay. The broadening of diffraction peak of PS/clay nanocomposites produced by melt intercalation was observed suggesting the structure of both intercalation and partial exfoliation; however, the impact strength was reasonably improved which can imply to the enhancement of interfacial adhesion between clay particles and polystyrene matrix. In addition, the ratio of styrene and initiator played the significant role on these properties as well.

Tasanatanachai, Patchara; Magaraphan, Rathanawan

2007-03-01

253

Dissolved carbonic anhydrase for enhancing post-combustion carbon dioxide hydration in aqueous ammonia  

SciTech Connect

Aqueous ammonia solvents that capture CO2 as ionic complexes of carbonates with ammonium have recently been advanced as alternatives to amine-based solvents due to their lower energy requirements for thermal regeneration. In ammonia based solvents, the hydration of CO2 to form bicarbonate may become a rate-limiting step as the CO2 loading increases and the resulting pH level of the solvent decreases. Variants of the enzyme carbonic anhydrase can accelerate the reversible hydration of CO2 to yield bicarbonate by more than 10(6)-fold. The possible benefit of bovine carbonic anhydrase (BCA) addition to solutions of aqueous ammonia to enhance CO2 hydration was investigated in semi-batch reactions within continuously stirred tank reactors or in a bubble column gas-liquid contactor. Adding 154 mg/liter of BCA to 2 M aqueous ammonia provided a 34.1% overall increase in the rate of CO2 hydration (as indicated by the production of [H+]) as the pH declined from 9.6 to 8.6 during sparging with a 15% CO2, 85% N-2 gas at a flow rate of 3 lpm. The benefits of adding BCA to enhance CO2 hydration were only discernable below similar to pH 9. The implications of the apparent pH limitations on the utility of BCA are discussed in the context of absorber unit operation design. Possible embodiments of carbonic anhydrase as either an immobilized catalyst or as a dissolved, recirculating catalyst in potential plant scale aqueous ammonia systems are considered as well. (C) 2010 Published by Elsevier Ltd.

Collett, James R.; Heck, Robert W.; Zwoster, Andy

2011-04-01

254

Feasibility study of enhanced combustion via improved wood stove firebox design. Final report Nov 84Jul 85  

Microsoft Academic Search

The report gives results of an examination of materials that might be used to line the firebox of a wood-burning stove to produce more uniform and complete combustion. (Emissions from incomplete combustion in wood-burning stoves are becoming an increasing environmental problem.) Although many materials were considered initially, refractory materials appear to possess the qualities desired relative to heat transfer, resistance

K. T. Fuentes; L. J. Hodas

1985-01-01

255

Enhancement of electrical property by oxygen doping to copper phthalocyanine in inverted top emitting organic light emitting diodes  

SciTech Connect

We reported the evidence of oxygen doping to copper-phthalocyanine (CuPc) by O{sub 2}-plasma treatment to inverted top-emitting organic light-emitting diodes (ITOLEDs). In situ synchrotron-radiation photoelectron spectroscopy results showed that a new Cu-O bond appeared and the energy difference between the highest-occupied molecular orbital and E{sub F} is lowered by 0.15 eV after plasma treatment. The oxygen ions chemically interacted with Cu atoms and transferred charges to the CuPc. Thus the hole injection barrier was lowered, enhancing the electroluminescent property of ITOLEDs.

Hong, Kihyon; Kim, Kisoo; Lee, Jong-Lam [Department of Materials Science and Engineering and Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), Pohang, Kyungbuk 790-784 (Korea, Republic of)

2009-11-23

256

Thermogravimetric studies of systems pertinent to the in-situ combustion process for enhanced oil recovery. Part 1. Development of a high-pressure thermobalance  

Microsoft Academic Search

A high-pressure (0–1000 psig) thermobalance experiment has been developed in order to obtain thermogravimetric (TG) and derivative thermogravimetry data (DTG) pertinent to the in-situ combustion process for enhanced oil recovery. Studies on the pressured thermo-oxidative behaviour of 20\\/80 (W\\/W) oil\\/sand and coked sand samples are reported.In the case of the oil\\/sand sample under a 100 psig non-oxidising atmosphere, distillation\\/evaporation occurred

S. Indrijarso; J. S. Oklany; A. Millington; D. Price; R. Hughes

1996-01-01

257

Enhanced oxygen transfer in tower bioreactor on addition of liquid hydrocarbons  

Microsoft Academic Search

A mixture of alkanes in the range of C12 to C16, byproducts of distillation processes in the petroleum industry, was used as an oxygen-vector. The effect on the oxygen transfer rate of addition of the alkane mixture to the medium in a tower bioreactor was investigated. A concentration of 4% (v\\/v) of the alkane mixture increased the volumetric oxygen transfer

Shiru Jia; Pe Li; Yong Soo Park; Mitsuyasu Okabe

1996-01-01

258

Physiologic Oxygen Enhances Human Embryonic Stem Cell Clonal Recovery and Reduces Chromosomal Abnormalities  

Microsoft Academic Search

Human embryonic stem cells (hESC) have great potential in regenerative medicine, provided that culture systems are established that maintain genomic integrity. Here we describe a com- parison of the effects of culture in either physiologic oxygen (2%) or room oxygen (21%) on the hESC lines, H1, H9, and RH1. Physiologic oxygen enabled an average sixfold increase in clone recovery across

Nicholas R. Forsyth; Antonio Musio; Paolo Vezzoni; A. Hamish R. W. Simpson; Brendon S. Noble; Jim McWhir

2006-01-01

259

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

260

Hydrogen and oxygen plasma enhancement in the Cu electrodeposition and consolidation processes on BDD electrode applied to nitrate reduction  

NASA Astrophysics Data System (ADS)

Copper nanoparticle electrodeposition and consolidation processes were studied on boron doped diamond (BDD) electrode submitted to hydrogen and oxygen plasma treatments. The modified BDD films were applied as electrodes for nitrate electroreduction. The results showed that both treatments have a strong influence on the copper deposition and dissolution processes. For BDD treated with hydrogen plasma the copper electrodeposit was homogeneous with high particle density. This behavior was attributed to the BDD surface hydrogenation that improved its conductivity. On the other hand, the treatment with oxygen plasma was important for the copper nanoparticle consolidation on BDD surface, confirmed by the result's reproducibility for nitrate reduction. This performance may be associated with the formation of oxygen groups that can act as anchor points for Cu-clusters, enhancing the interfacial adhesion between diamond and the metal coating. The best electrochemical nitrate reduction response was obtained in acid media, where occurred the separation of the nitrate reduction process and the water reduction reaction.

Couto, A. B.; Santos, L. C. D.; Matsushima, J. T.; Baldan, M. R.; Ferreira, N. G.

2011-09-01

261

Plasma-assisted combustion: Systematic decoupling of the kinetic enhancement mechanisms of ignition, flame propagation, and flame stabilization by long-lifetime species  

NASA Astrophysics Data System (ADS)

The advancement of propulsion devices and combustion systems has created ever increasingly more restrictive reactive environments that push the limits of combustion technology. Precise combustion control for higher efficiencies, reduced emissions, and limited residence times to react can exceed what is possible with traditional combustion chemistry, and therefore require new and creative solutions. The application of plasma to combustion systems offers a promising solution, with significant enhancement having been shown by many researchers. Nevertheless, there remain many unknowns with respect to the key species and mechanisms of enhancement. Detailed systematic experimental and numerical investigations were performed to identify the kinetic mechanisms of combustion enhancement by long-lifetime species generated by non-equilibrium plasma discharges. Two burner systems were adopted and integrated with plasma discharge devices to establish unique combustion platforms to study ignition, flame propagation, and flame stabilization phenomena. A counterflow diffusion flame burner was adopted for the investigation of the effects of plasma on flame stabilization. A newly developed non-equilibrium magnetic gliding arc plasma discharge was integrated with a counterflow diffusion flame burner and was found to significantly extend the limits of flame stabilization when activating air. Laser diagnostic methods of planar Rayleigh scattering and OH planar laser-induced fluorescence were applied and comparison to numerical simulations showed that the extension of the extinction limits was predominately through thermal effects due to rapid recombination of radicals. To elucidate the kinetic effects of plasma, the counterflow burner was augmented for ignition experiments. The application of Fourier transform infrared spectroscopy and comparison to numerical simulations showed significant kinetic ignition enhancement by plasma-produced NOx when activating air. The results established the existence of new ignition regimes for NO x addition that were strongly dependent upon the strain rates (residence times) in the system. The addition of small concentrations of fuel to the air upstream of the plasma produced fuel fragments and partially oxidized products that inhibited ignition. The dominating effects of plasma-produced NOx significantly mitigated the inhibitive effects of these species on chain-branching reaction pathways. To further decouple the plasma-flame interaction, the two long-lifetime plasma species of O3 and O2(a1Delta g) were produced, isolated, measured, and transported to a lifted flame burner to investigate their effect on flame propagation speed. The effects of O3 at atmospheric and sub-atmospheric pressure were found to be significant because of the decomposition of O3 releasing O to rapidly react with the fuel and extract chemical heat early in the pre-heat zone of the flame. The effect of O2(a1Delta g) was isolated by the addition of NO to the plasma afterglow to eliminate O3 and O catalytically. The O2(a1Delta g) was isolated, measured quantitatively using high sensitivity off-axis integrated cavity output absorption spectroscopy, and observed to enhance flame speed. The comparison of experimental and numerical simulation results showed that the current enhancement mechanism including O2(a 1Deltag) could not accurately explain the increase in flame speed observed. Furthermore, a novel filter system was developed to minimize the concentration of all plasma-produced species other than O3 and O2(a1Deltag) through gas phase and wall surface quenching. Lastly, a new simplified and well-defined plasma-combustion system was developed to provide a platform to study the plasma-flame interaction. In addition, a flow visualization technique was proposed by using plasma activation and NO seeding which could be applied to a system where particle seeding of the flow is prohibitive.

Ombrello, Timothy M.

262

Chemisorption of oxygen onto activated carbon can enhance the stability of biological perchlorate reduction in fixed bed biofilm reactors.  

PubMed

Fixed bed biofilm reactors with granular activated carbon (GAC) or glass beads as support media were used to evaluate the influence of short-term (12h) and long-term (23 days) increases of influent dissolved oxygen (DO) concentrations on biological perchlorate removal. The goal was to evaluate the extent by which chemisorption of oxygen to GAC can enhance the stability of biological perchlorate reduction. Baseline influent concentrations were 50 microg/L of perchlorate, 2 mg/L of acetate as C, and 1mg/L of DO. Perchlorate removal in the glass bead reactor seized immediately after increasing influent DO concentrations from 1 to 4 mg/L since glass beads have no sorptive capacity. In the biologically active carbon (BAC) reactor, chemisorption of oxygen to GAC removed a substantial fraction of the influent DO, and perchlorate removal was maintained during short-term increases of influent DO levels up to 8 mg/L. During long-term exposure to influent DO concentrations of 8.5mg/L, effluent perchlorate and DO concentrations increased slowly. Subsequent exposure of the BAC reactor bed to low DO concentrations partially regenerated the capacity for oxygen chemisorption. Microbial analyses indicated similar microbial communities in both reactors, which confirmed that the differences in reactor performance during dynamic loading conditions could be attributed to the sorptive properties of GAC. Using a sorptive biofilm support medium can enhance biological perchlorate removal under dynamic loading conditions. PMID:18554683

Choi, Young Chul; Li, Xu; Raskin, Lutgarde; Morgenroth, Eberhard

2008-05-16

263

Enhanced Generation of Reactive Oxygen Species in the Limb Skeletal Muscles From a Murine Infarct Model of Heart Failure  

Microsoft Academic Search

Background—The generation of reactive oxygen species (ROS) is enhanced in the failing myocardium. We hypothesized that ROS were also increased in the limb skeletal muscles in heart failure. Methods and Results—Myocardial infarction (MI) was created in mice by ligating the left coronary artery. After 4 weeks, the left ventricle was dilated and contractility was diminished by echocardiography. Left ventricular end-diastolic

Hiroyuki Tsutsui; Tomomi Ide; Shunji Hayashidani; Nobuhiro Suematsu; Tetsuya Shiomi; Jing Wen; Kei-ichiro Nakamura; Kazuhiro Ichikawa; Hideo Utsumi; Akira Takeshita

264

Incompatible pathogen infection results in enhanced reactive oxygen and cell death responses in transgenic tobacco expressing a hyperactive mutant calmodulin  

Microsoft Academic Search

.   Transgenic tobacco (Nicotiana tabacum L. cv. Wisconsin 38) lines expressing a mutant calmodulin (VU-3) that hyperactivates NAD kinase exhibit an enhanced elicitor-stimulated\\u000a oxidative-burst reaction (S.A. Harding et al., 1997, EMBO J. 16: 1137–1144). VU-3 transgenic tobacco was used in the present\\u000a study to investigate the relationship between calmodulin signalling, the production of active oxygen species and cell death\\u000a in

Scott A. Harding; Daniel M. Roberts

1998-01-01

265

Combustion Enhancement and Pollutant Control Research with Acoustically Induced Mixing. Technical Progress Report, September 1981-December 1981.  

National Technical Information Service (NTIS)

An experimental research program has been initiated to evaluate the possibility that beneficial effects can result when acoustic energy is impressed on the combustion zone of pulverized coal furnaces. These benefits include the reduction in NO/sub x/ gene...

R. J. Faeser M. I. Rudnicki

1982-01-01

266

Pretreatment of Parsley (Petroselinum crispum L.) Suspension Cultures with Methyl Jasmonate Enhances Elicitation of Activated Oxygen Species.  

PubMed

Suspension-cultured cells of parsley (Petroselinum crispum L.) were used to demonstrate an influence of jasmonic acid methyl ester (JAME) on the elicitation of activated oxygen species. Preincubation of the cell cultures for 1 d with JAME greatly enhanced the subsequent induction by an elicitor preparation from cell walls of Phytophtora megasperma f. sp. glycinea (Pmg elicitor) and by the polycation chitosan. Shorter preincubation times with JAME were less efficient, and the effect was saturated at about 5 [mu]M JAME. Treatment of the crude Pmg elicitor with trypsin abolished induction of activated oxygen species, an effect similar to that seen with elicitation of coumarin secretion. These results suggest that JAME conditioned the parsley suspension cells in a time-dependent manner to become more responsive to elicitation, reminiscent of developmental effects caused by JAME in whole plants. It is interesting that pretreatment of the parsley cultures with 2,6-dichloroisonicotinic and 5-chlorosalicylic acid only slightly enhanced the elicitation of activated oxygen species, whereas these substances greatly enhanced the elicitation of coumarin secretion. Therefore, these presumed inducers of systemic acquired resistance exhibit a specificity different from JAME. PMID:12232189

Kauss, H.; Jeblick, W.; Ziegler, J.; Krabler, W.

1994-05-01

267

Pretreatment of Parsley (Petroselinum crispum L.) Suspension Cultures with Methyl Jasmonate Enhances Elicitation of Activated Oxygen Species.  

PubMed Central

Suspension-cultured cells of parsley (Petroselinum crispum L.) were used to demonstrate an influence of jasmonic acid methyl ester (JAME) on the elicitation of activated oxygen species. Preincubation of the cell cultures for 1 d with JAME greatly enhanced the subsequent induction by an elicitor preparation from cell walls of Phytophtora megasperma f. sp. glycinea (Pmg elicitor) and by the polycation chitosan. Shorter preincubation times with JAME were less efficient, and the effect was saturated at about 5 [mu]M JAME. Treatment of the crude Pmg elicitor with trypsin abolished induction of activated oxygen species, an effect similar to that seen with elicitation of coumarin secretion. These results suggest that JAME conditioned the parsley suspension cells in a time-dependent manner to become more responsive to elicitation, reminiscent of developmental effects caused by JAME in whole plants. It is interesting that pretreatment of the parsley cultures with 2,6-dichloroisonicotinic and 5-chlorosalicylic acid only slightly enhanced the elicitation of activated oxygen species, whereas these substances greatly enhanced the elicitation of coumarin secretion. Therefore, these presumed inducers of systemic acquired resistance exhibit a specificity different from JAME.

Kauss, H.; Jeblick, W.; Ziegler, J.; Krabler, W.

1994-01-01

268

A review of inlet air-cooling technologies for enhancing the performance of combustion turbines in Saudi Arabia  

Microsoft Academic Search

Peak demand for electric power in Saudi Arabia occurs during the middle of the day in summer and is almost double the off-peak demand. The demand profile is ill-matched to the performance profile of combustion turbines as their power output decreases with increased inlet-air temperature. Approximately 42% of the Saudi Electric Company’s (SEC) annual energy sales are generated by combustion

Abdulrahman M. Al-Ibrahim; Abdulhadi Varnham

2010-01-01

269

Enhanced oxygen diffusivity in interfaces of nanocrystalline ZrO2.Y2O3.  

PubMed

First measurements of oxygen grain boundary diffusion coefficients in nanocrystalline yttria-doped ZrO(2) (n-ZrO(2).6.9 mol % Y(2)O(3)) are presented. The (18)O diffusion profiles measured by secondary ion mass spectroscopy are much deeper in the nanocrystalline specimens than in single crystals. An oxygen diffusivity, D(B), in the grain boundaries can be deduced, which is approximately 3 orders of magnitude higher than in single crystals. From the present data the temperature variation of the oxygen grain boundary diffusivity, D(B) = 2.0 x 10(-5) exp (-0.91 eVk(B)T) m(2)s, and the oxygen surface exchange coefficient, k = 1.4 x 10(-2) exp (-1.13 eVk(B)T) ms, are derived. PMID:12655074

Knoner, Gregor; Reimann, Klaus; Rower, Ralf; Sodervall, Ulf; Schaefer, Hans-Eckhardt

2003-03-24

270

Enhanced electrocatalysis of the oxygen reduction reaction based on patterning of platinum surfaces with cyanide  

NASA Astrophysics Data System (ADS)

The slow rate of the oxygen reduction reaction in the phosphoric acid fuel cell is the main factor limiting its wide application. Here, we present an approach that can be used for the rational design of cathode catalysts with potential use in phosphoric acid fuel cells, or in any environments containing strongly adsorbing tetrahedral anions. This approach is based on molecular patterning of platinum surfaces with cyanide adsorbates that can efficiently block the sites for adsorption of spectator anions while the oxygen reduction reaction proceeds unhindered. We also demonstrate that, depending on the supporting electrolyte anions and cations, on the same CN-covered Pt(111) surface, the oxygen reduction reaction activities can range from a 25-fold increase to a 50-fold decrease. This behaviour is discussed in the light of the role of covalent and non-covalent interactions in controlling the ensemble of platinum active sites required for high turn over rates of the oxygen reduction reaction.

Strmcnik, Dusan; Escudero-Escribano, María; Kodama, Kensaku; Stamenkovic, Vojislav R.; Cuesta, Angel; Markovi?, Nenad M.

2010-10-01

271

Enhanced oxygen diffusivity in interfaces of nanocrystalline ZrO2?Y2O3  

PubMed Central

First measurements of oxygen grain boundary diffusion coefficients in nanocrystalline yttria-doped ZrO2 (n-ZrO2?6.9 mol % Y2O3) are presented. The 18O diffusion profiles measured by secondary ion mass spectroscopy are much deeper in the nanocrystalline specimens than in single crystals. An oxygen diffusivity, DB, in the grain boundaries can be deduced, which is ?3 orders of magnitude higher than in single crystals. From the present data the temperature variation of the oxygen grain boundary diffusivity, DB = 2.0 × 10?5 exp (?0.91 eV/kBT) m2/s, and the oxygen surface exchange coefficient, k = 1.4 × 10?2 exp (?1.13 eV/kBT) m/s, are derived.

Knoner, Gregor; Reimann, Klaus; Rower, Ralf; Sodervall, Ulf; Schaefer, Hans-Eckhardt

2003-01-01

272

ENHANCED BIOREMEDIATION UTILIZING HYDROGEN PEROXIDE AS A SUPPLEMENTAL SOURCE OF OXYGEN: A LABORATORY AND FIELD STUDY  

EPA Science Inventory

Laboratory and field scale studies were conducted to investigate the feasibility of using hydrogen peroxide as a supplemental source of oxygen for bioremediation of an aviation gasoline fuel spill. Field samples of aviation gasoline contaminated aquifer material were artificially...

273

Enhanced electrocatalysis of the oxygen reduction reaction based on pattering of platinum surfaces with cyanide.  

SciTech Connect

The slow rate of the oxygen reduction reaction in the phosphoric acid fuel cell is the main factor limiting its wide application. Here, we present an approach that can be used for the rational design of cathode catalysts with potential use in phosphoric acid fuel cells, or in any environments containing strongly adsorbing tetrahedral anions. This approach is based on molecular patterning of platinum surfaces with cyanide adsorbates that can efficiently block the sites for adsorption of spectator anions while the oxygen reduction reaction proceeds unhindered. We also demonstrate that, depending on the supporting electrolyte anions and cations, on the same CN-covered Pt(111) surface, the oxygen reduction reaction activities can range from a 25-fold increase to a 50-fold decrease. This behaviour is discussed in the light of the role of covalent and non-covalent interactions in controlling the ensemble of platinum active sites required for high turn over rates of the oxygen reduction reaction.

Strmcnik, D.; Escudero-Escribano, M.; Kodama, K.; Stamenkovic, V. R.; Cuesta, A.; Markovic, N. M.; Materials Science Division; Inst. de Quimica Fisica; Toyota Central R& D Labs., Inc.

2010-08-15

274

Enhanced oxygen diffusivity in interfaces of nanocrystalline ZrO2·Y2O3  

Microsoft Academic Search

First measurements of oxygen grain boundary diffusion coefficients in nanocrystalline yttria-doped ZrO2 (n-ZrO2·6.9 mol % Y2O3) are presented. The 18O diffusion profiles measured by secondary ion mass spectroscopy are much deeper in the nanocrystalline specimens than in single crystals. An oxygen diffusivity, DB, in the grain boundaries can be deduced, which is 3 orders of magnitude higher than in single

Gregor Knöner; Klaus Reimann; Ralf Röwer; Ulf Södervall; Hans-Eckhardt Schaefer

2003-01-01

275

Diffusion Limitation and Hyperoxic Enhancement of Oxygen Consumption in Zooxanthellate Sea Anemones, Zoanthids, and Corals  

Microsoft Academic Search

Absfract. Depending on their size and morphology, anthozoan polyps and colonies may be diffusion-limited in their oxygen consumption, even under well-stirred, air-saturated conditions. This is indicated by an en hancement of oxygen consumption under steady-state hyperoxic conditions that simulate the levels of 02 pro duced photosynthetically by zooxanthellae in the hosts' tissues. Such hyperoxia in the tissues of zooxanthellate species

J. MALCOLM SHICK

1990-01-01

276

Enhanced photocatalytic activity of TiO 2-incorporated nanofiber membrane by oxygen plasma treatment  

Microsoft Academic Search

In this paper, we report on the high-performance photocatalysis of polymeric TiO2 membranes modified by oxygen plasma treatment for water purification. TiO2-nanopowder-incorporated poly ?-caprolactone (PCL\\/TiO2; PT) nanofibers were prepared by electrospinning at various concentrations of TiO2 (1, 3, 5, and 7wt.%) and then treated by atmospheric plasma with oxygen gas (OAP). As the TiO2 content increased, the surface roughness and

S. Y. Park; H. U. Lee; K. Ahn; J. P. Kim; J. S. Jin; J. Lee; S. Y. Jeong; C. R. Cho

2011-01-01

277

Enhancement of oxygen transfer in liquid lead and lead–bismuth eutectic by natural convection  

Microsoft Academic Search

The present study carries out numerical analysis of the coupled natural convection and oxygen transfer of low-Prandtl-number (?0.02) liquid lead and lead–bismuth eutectic (LBE) for testing and calibrating low concentration level oxygen sensors. The analysis is performed on the two-dimensional coordinates in a rectangular container, where the fluid movement is laminar for the purpose of sensor test and calibration. The

Jian Ma; Peng Guo; Jinsuo Zhang; Ning Li; Bingmei M. Fu

2005-01-01

278

Epirubicin cytotoxicity but not oxygen radical formation is enhanced by four different antiemetics  

Microsoft Academic Search

The anthracycline epirubicin (0.1?1.0 mg 1.?1) caused a dose-dependent inhibition of the clonogenic survival of Chinese hamster fibroblasts. Four antiemetics (dixyrazin,\\u000a metoclopramide, chlorpromazine and droperidol) augmented the inhibition by epirubicin. Furthermore, by using oxygen consumption\\u000a as an index, epirubicininduced free oxygen radical formation was not potentiated by the tested antiemetics. The results justify\\u000a further studies on the antineoplastic and adverse

Roger Henriksson; Kjell Grankvist

1989-01-01

279

Coal Combustion Science  

SciTech Connect

The objective of this activity is to support the Office of Fossil Energy in executing research on coal combustion science. This activity consists of basic research on coal combustion that supports both the Pittsburgh Energy Technology Center Direct Utilization Advanced Research and Technology Development Program, and the International Energy Agency Coal Combustion Science Project. Specific tasks for this activity include: (1) coal devolatilization - the objective of this risk is to characterize the physical and chemical processes that constitute the early devolatilization phase of coal combustion as a function of coal type, heating rate, particle size and temperature, and gas phase temperature and oxidizer concentration; (2) coal char combustion -the objective of this task is to characterize the physical and chemical processes involved during coal char combustion as a function of coal type, particle size and temperature, and gas phase temperature and oxygen concentration; (3) fate of mineral matter during coal combustion - the objective of this task is to establish a quantitative understanding of the mechanisms and rates of transformation, fragmentation, and deposition of mineral matter in coal combustion environments as a function of coal type, particle size and temperature, the initial forms and distribution of mineral species in the unreacted coal, and the local gas temperature and composition.

Hardesty, D.R. (ed.); Fletcher, T.H.; Hurt, R.H.; Baxter, L.L. (Sandia National Labs., Livermore, CA (United States))

1991-08-01

280

Nutrients and oxygen alter reservoir biochemical characters and enhance oil recovery during biostimulation.  

PubMed

Biostimulation of petroleum reservoir to improve oil recovery has been conducted in a large number of oilfields. However, the roles and linkages of organic nutrients, inorganic salts and oxygen content during biostimulation have not been effectively elucidated. Therefore, we investigated the relationships between carbon source, nitrogen source, phosphorus source, oxygen content, and microbial stimulation, oil emulsification, and oil degradation. The organic nutrients (molasses) accelerated microbial growth, and promoted oil emulsification under aerobic conditions. The added molasses also promoted metabolites production (CO2, CH4 and acetic acid) and microbial anaerobic hydrocarbon degradation under anaerobic conditions. (NH4)2HPO4 improved gases production by neutralizing the acidic production and molasses. NaNO3 could also improve gases production by inhibiting sulfate-reducing bacteria to adjust pH value. Oxygen supply was necessary for oil emulsification, but bountiful supply of oxygen aggravated oil degradation, leading the entire ranges of alkanes and some aromatic hydrocarbons were degraded. Core-flooding experiments showed an oil displacement efficiency of 13.81 % in test with air package injected, 8.56 % without air package injection, and 4.77 % in control test with air package injection and 3.61 % without air package injection. The results suggest that the combined effect of organic nutrients, inorganic salts and oxygen content determines microbial growth, while production of metabolites, oil emulsification and biodegradation alter the reservoir biochemical characters and influence oil recovery during stimulation. PMID:23700126

Gao, Peike; Li, Guoqiang; Dai, Xuecheng; Dai, Liubing; Wang, Hongbo; Zhao, Lingxia; Chen, Yuehua; Ma, Ting

2013-05-23

281

Using fluorochemical as oxygen carrier to enhance the growth of marine microalga Nannochloropsis oculata.  

PubMed

The commercial value of marine Nannochloropsis oculata has been recognized due to its high content of eicosapentaenoic acid (>50% w/w). To make it as a profitable bioresource, one of the most desirable goals is to develop a quality-controlled, cost-effective, and large-scale photobioreactor for N. oculata growth. Generally, closed culture system can offer many advantages over open system such as small space requirement, controllable process and low risk of contamination. However, oxygen accumulation is often a detrimental factor for enclosed microalgal culture that has seriously hampered the development of microalga-related industries. In this study, we proposed to use fluorochemical as oxygen carrier to overcome the challenge where four liquid fluorochemicals namely perfluorooctyl bromide, perfluorodecalin, methoxynonafluorobutane, and ethoxynonafluorobutane were investigated separately. Our results showed that the microalgal proliferation with different fluorinated liquids was similar and comparable to the culture without a fluorochemical. When cultured in the photobioreactor with 60% oxygen atmosphere, the N. oculata can grow up in all the fluorochemical photobioreactors, but completely inhibited in the chamber without a fluorochemical. Moreover, the perfluorooctyl bromide system exhibited the most robust efficacy of oxygen removal in the culture media (perfluorooctyl bromide > perfluorodecalin > methoxynonafluorobutane > ethoxynonafluorobutane), and yielded a >3-fold increase of biomass production after 5 days. In summary, the developed fluorochemical photobioreactors offer a feasible means for N. oculata growth in closed and large-scale setting without effect of oxygen inhibition. PMID:23178985

Lee, Yu-Hsiang; Yeh, Yu-Ling; Lin, Keng-Hsien; Hsu, Yu-Chih

2012-11-20

282

Field-scale investigation of enhanced petroleum hydrocarbon biodegradation in the vadose zone combining soil venting as an oxygen source with moisture and nutrient addition. Appendices. Doctoral thesis  

SciTech Connect

This document contains appendices regarding a reprint on a field scale investigation of enhanced petroleum hydrocarbon biodegradation in the vadose zone combining soil venting as a oxygen source with moisture and nutrient addition.

Miller, R.N.

1990-01-01

283

Photooxidation of alkaloids: considerable quantum yield enhancement by rose bengal-sensitized singlet molecular oxygen generation.  

PubMed

The photooxidation of sanguinarine, coralyne and berberine was studied in oxygenated alkaline methanol solutions. Rose bengal as photosensitizer significantly accelerates the process, indicating the importance of singlet molecular oxygen in the reaction mechanism. The quantum yield of sensitized oxidation was found to increase significantly with pH and reaches 0.4 for berberine at pH 13.8. The direct oxidation of alkaloids is less efficient, the quantum yield does not exceed 0.01 even in oxygen-saturated solutions. The photoinduced electron ejection does not play a role in the oxidation. The uncharged pseudobase forms, which are present in alkaline medium, are oxidized much more easily than the alkaloid cations. PMID:21883246

Görner, Helmut; Miskolczy, Zsombor; Megyesi, Mónika; Biczók, László

2011-10-03

284

An algorithm for sensing venous oxygenation using ultrasound-modulated light enhanced by microbubbles  

NASA Astrophysics Data System (ADS)

Near-infrared spectroscopy (NIRS) can provide an estimate of the mean oxygen saturation in tissue. This technique is limited by optical scattering, which reduces the spatial resolution of the measurement, and by absorption, which makes the measurement insensitive to oxygenation changes in larger deep blood vessels relative to that in the superficial tissue. Acousto-optic (AO) techniques which combine focused ultrasound (US) with diffuse light have been shown to improve the spatial resolution as a result of US-modulation of the light signal, however this technique still suffers from low signal-to-noise when detecting a signal from regions of high optical absorption. Combining an US contrast agent with this hybrid technique has been proposed to amplify an AO signal. Microbubbles are a clinical contrast agent used in diagnostic US for their ability to resonate in a sound field: in this work we also make use of their optical scattering properties (modelled using Mie theory). A perturbation Monte Carlo (pMC) model of light transport in a highly absorbing blood vessel containing microbubbles surrounded by tissue is used to calculate the AO signal detected on the top surface of the tissue. An algorithm based on the modified Beer-Lambert law is derived which expresses intravenous oxygen saturation in terms of an AO signal. This is used to determine the oxygen saturation in the blood vessel from a dual wavelength microbubble-contrast AO measurement. Applying this algorithm to the simulation data shows that the venous oxygen saturation is accurately recovered, and this measurement is robust to changes in the oxygenation of the superficial tissue layer.

Honeysett, Jack E.; Stride, Eleanor; Deng, Jing; Leung, Terence S.

2012-02-01

285

Multistage process for combusting fuel mixtures using oxide catalysts in the hot stage  

Microsoft Academic Search

A process is described for partially combusting combustible mixtures comprising the steps of: (a) mixing an oxygen-containing gas with a fuel to form a combustible mixture, (b) contacting the combustible mixture in a first zone with a first zone combustion catalyst comprising palladium completely covering a catalyst support at reaction conditions sufficient to combust at least a portion but not

R. A. Dalla Betta; Kazunori Tsurumi; Nobuyasu. Ezawa

1993-01-01

286

Combustion leftovers  

Microsoft Academic Search

Combustion processes almost never completely exhaust all of the available fuel. In this paper, we will consider three combustion scenarios (back-to-back premixed flames in stagnation point flow, travelling combustion waves, and microgravity spherical flame balls) and show how to calculate the amount of fuel which will be left over no matter how long we allow the combustion processes to continue.

R. O Weber; G. N Mercer; H. S Sidhu

2002-01-01

287

Enhancement of the electroreduction of oxygen on Pt alloys with Fe, Ni, and Co  

Microsoft Academic Search

Electrocatalytic activity of Pt alloys with Ni, Co, and Fe, formed by sputtering, was investigated with regard to the oxygen reduction reaction (ORR) in perchloric acid solution. Hydrodynamic voltammograms with rotated electrodes were used to measure the electrocatalytic activity. Maximum activity was observed at ca. 30, 40, and 50% content of Ni, Co, and Fe, respectively, by which 10, 15,

Takako Toda; Hiroshi Igarashi; Hiroyuki Uchida; Masahiro Watanabe

1999-01-01

288

Durability enhancement and degradation of oxygen evolution anodes in seawater electrolysis for hydrogen production  

Microsoft Academic Search

For the anode composed of electrocatalyst oxide, intermediate layer and titanium substrate, the substitution of a certain amount of iridium with tin in the IrO2 intermediate layer was remarkably effective in elongating the life of the anode in preventing oxidation of the substrate titanium during oxygen evolution. The longest life was realized by preparation of intermediate layer with uniform thickness

Zenta Kato; Jagadeesh Bhattarai; Naokazu Kumagai; Koichi Izumiya; Koji Hashimoto

2011-01-01

289

Enhanced oxygen supply improves islet viability in a new bioartificial pancreas.  

PubMed

The current epidemic of diabetes with its overwhelming burden on our healthcare system requires better therapeutic strategies. Here we present a promising novel approach for a curative strategy that may be accessible for all insulin-dependent diabetes patients. We designed a subcutaneous implantable bioartificial pancreas (BAP)-the "?-Air"-that is able to overcome critical challenges in current clinical islet transplantation protocols: adequate oxygen supply to the graft and protection of donor islets against the host immune system. The system consists of islets of Langerhans immobilized in an alginate hydrogel, a gas chamber, a gas permeable membrane, an external membrane, and a mechanical support. The minimally invasive implantable device, refueled with oxygen via subdermally implanted access ports, completely normalized diabetic indicators of glycemic control (blood glucose intravenous glucose tolerance test and HbA1c) in streptozotocin-induced diabetic rats for periods up to 6 months. The functionality of the device was dependent on oxygen supply to the device as the grafts failed when oxygen supply was ceased. In addition, we showed that the device is immuno-protective as it allowed for survival of not only isografts but also of allografts. Histological examination of the explanted devices demonstrated morphologically and functionally intact islets; the surrounding tissue was without signs of inflammation and showed visual evidence of vasculature at the site of implantation. Further increase in islets loading density will justify the translation of the system to clinical trials, opening up the potential for a novel approach in diabetes therapy. PMID:23043896

Barkai, Uriel; Weir, Gordon C; Colton, Clark K; Ludwig, Barbara; Bornstein, Stefan R; Brendel, Mathias D; Neufeld, Tova; Bremer, Chezi; Leon, Assaf; Evron, Yoav; Yavriyants, Karina; Azarov, Dimitri; Zimermann, Baruch; Maimon, Shiri; Shabtay, Noa; Balyura, Maria; Rozenshtein, Tania; Vardi, Pnina; Bloch, Konstantin; de Vos, Paul; Rotem, Avi

2012-10-03

290

Diffuser System Modeling and Design for Dissolved Oxygen Enhancement of Reservoirs and Releases  

Microsoft Academic Search

In support of the Tennessee Valley Authority's Lake Improvement Program, a line diffuser system was developed that was applied and proven effective at six TVA hydropower projects. To be effective, the placement of the diffusers and distribution of the oxygen input must be optimized for site-specific water quality and water flow conditions. Most TVA applications were relatively straightforward designs with

Mark H. Mobley; Gary E. Hauser; Dan F. McGinnis; R. Jim Ruane

291

Combustion method for simultaneous control of nitrogen oxides and products of incomplete combustion  

SciTech Connect

A method is described for combusting material with controlled generation of both nitrogen oxides and products of incomplete combustion comprising: (A) combusting material in a first combustion zone to produce gaseous exhaust containing products of incomplete combustion and products of complete combustion; (B) passing the gaseous exhaust from the first combustion zone into a second combustion zone having a width and an axial direction; (C) injecting through a lance with an orientation substantially parallel to said axial direction at least one stream of oxidant, without fuel, having a diameter less than 1/100 of the width of the second combustion zone and having an oxygen concentration of at least 30% into the second combustion zone at a high velocity of at least 300 feet per second; (D) aspirating products of incomplete combustion into the high velocity oxidant; (E) combusting products of incomplete combustion aspirated into the high velocity oxidant with high velocity oxidant within the second combustion zone to carry out a stable combustion by the mixing of the aspirated products of incomplete combustion with the high velocity oxidant; and (F) spreading out the combustion reaction by aspiration of products of complete combustion into the oxidant, said products of complete combustion also serving as a heat sink, to inhibit NO[sub x] formation.

Ho, Min-Da.

1993-05-25

292

Cathodic current enhancement via manganese and oxygen related reactions in marine biofilms  

Microsoft Academic Search

Corrosion is a threat that has economic, and environmental impacts worldwide. Many types of corrosive attack are the subject of ongoing research. One of these areas of research is microbiologically influenced corrosion, which is the enhancement and\\/or initiation of corrosion events caused by microorganisms. It is well known that colonies of microorganisms can enhance cathodic currents through biofilm formation. The

Matthew James Strom

2010-01-01

293

Enhanced Shrinkage of Lanthanum Strontium Manganite (La0.90Sr0.10MnO3+?) Resulting from Thermal and Oxygen Partial Pressure Cycling  

SciTech Connect

Exposure of La0.9Sr0.1MnO3+? to repeated oxygen partial pressure cycles (air/10 ppm O2) resulted in enhanced densification rates, similar to behavior shown previously due to thermal cycling. Shrinkage rates in the temperature range 700 to 1000oC were orders of magnitude higher than Makipirtti-Meng model estimations based on stepwise isothermal dilatometry results at high temperature. A maximum in enhanced shrinkage due to oxygen partial pressure cycling occurred at 900oC. Shrinkage was greatest when LSM-10 bars that were first equilibrated in air were exposed to gas flows of lower oxygen fugacity than in the reverse direction. The former creates transient cation and oxygen vacancies well above the equilibrium concentration, resulting in enhanced mobility. These vacancies annihilate as Schottky equilibria is re-established, whereas the latter condition does not lead to excess vacancy concentrations.

McCarthy, Ben; Pederson, Larry R.; Anderson, Harlan U.; Zhou, Xiao Dong; Singh, Prabhakar; Coffey, Greg W.; Thomsen, Ed C.

2007-10-01

294

Enhanced oxygen transfer rates in fermentation using soybean oil-in-water dispersions  

Microsoft Academic Search

Summary The effect of soybean oil on the volumetric oxygen transfer coefficient during the cultivation ofAerobacter aerogenes cells is presented. For our aeration-agitation conditions (0.278 vvm and 500 rpm), it has been demonstrated that the use 19% (v\\/v) of soybean oil enabled a 1.85-fold increase of thekl a coefficient (calculated on a per liter aqueous phase basis). For smaller volumetric

J. L. Rols; G. Goma

1991-01-01

295

A possibility of the oxygen diffusion enhancement in YSZ: a molecular dynamics study  

Microsoft Academic Search

A constant volume molecular dynamics calculation has been carried out for an yttria stabilized zirconia (YSZ) with composition (ZrO2)0.8(Y2O3)0.2, in which Y ions are artificially arranged in layers. The oxygen ion diffusion coefficient in the artificial YSZ is larger than that in YSZ with a random distribution of Y ions. A way of synthesizing YSZ with a larger value of

Hideo Okazaki; Hisashi Suzuki; Katsuyoshi Ihata

1994-01-01

296

Sunscreen enhancement of UV-induced reactive oxygen species in the skin  

Microsoft Academic Search

The number of UV-induced (20 mJ cm?2) reactive oxygen species (ROS) generated in nucleated epidermis is dependent upon the length of time the UV filter octocrylene, octylmethoxycinnamate, or benzophenone-3 remains on the skin surface. Two-photon fluorescence images acquired immediately after application of each formulation (2 mg cm?2) to the skin surface show that the number of ROS produced is dramatically reduced relative

Kerry M. Hanson; Enrico Gratton; Christopher J. Bardeen

2006-01-01

297

Computational and experimental study of oxygen-enhanced axisymmetric laminar methane flames  

Microsoft Academic Search

Three axisymmetric laminar coflow diffusion flames, one of which is a nitrogen-diluted methane\\/air flame (the ‘base case’) and the other two of which consist of nitrogen-diluted methane vs. pure oxygen, are examined both computationally and experimentally. Computationally, the local rectangular refinement method is used to solve the fully coupled nonlinear conservation equations on solution-adaptive grids. The model includes C2 chemistry

Beth Anne V. Bennett; Zhongxian Cheng; Robert W. Pitz; Mitchell D. Smooke

2008-01-01

298

Synergistic enhancement of protoplast growth by oxygenated perfluorocarbon and Pluronic F-68  

Microsoft Academic Search

Summary  Cell suspension-derived protoplasts of albino Petunia hybrida were grown for 10 d at the interface between aqueous culture medium (KM8P) and an oxygenated (10 mbar for 15 min) perfluorocarbon liquid, perfluorodecalin. Protoplasts synthesised new cell walls and divided normally at the perfluorodecalin\\/culture medium interface, with a mean viability after 10 d of > 92.0%. The mean plating efficiency of protoplasts

P. Anthony; M. R. Davey; J. B. Power; K. C. Lowe

1994-01-01

299

Strongly enhanced incorporation of oxygen into barium titanate based multilayer ceramic capacitors using water vapor  

SciTech Connect

The reoxidation of sintered BaTiO{sub 3}-based multilayer ceramic capacitors (MLCCs) is currently an empirically determined, but poorly understood, procedure. In this work, the incorporation of oxygen into BaTiO{sub 3}-based MLCCs has been studied by means of isotope exchange annealing ({sup 18}O{sub 2}/{sup 16}O{sub 2}, {sup 1}H{sub 2}{sup 18}O/{sup 1}H{sub 2}{sup 16}O or {sup 2}H{sub 2}{sup 16}O/{sup 1}H{sub 2}{sup 16}O) and subsequent determination of the isotope profiles in the solid by secondary ion mass spectrometry. Oxygen isotope profiles in the barium titanate dielectric can be described by a bulk diffusion coefficient D* and a surface exchange coefficient k*. The values obtained for k* indicate that oxygen incorporation from H{sub 2}O is much faster than from dry O{sub 2}; it thus plays the key role in the reoxidation process.

Kessel, M.; De Souza, R. A.; Martin, M. [Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen (Germany); Yoo, H.-I. [Department of Materials Science and Engineering, Seoul National University, Seoul 151-742 (Korea, Republic of)

2010-07-12

300

Flow enhances photosynthesis in marine benthic autotrophs by increasing the efflux of oxygen from the organism to the water  

PubMed Central

Worldwide, many marine coastal habitats are facing rapid deterioration due in part to human-driven changes in habitat characteristics, including changes in flow patterns, a factor known to greatly affect primary production in corals, algae, and seagrasses. The effect of flow traditionally is attributed to enhanced influx of nutrients and dissolved inorganic carbon (DIC) across the benthic boundary layer from the water to the organism however, here we report that the organism’s photosynthetic response to changes in the flow is nearly instantaneous, and that neither nutrients nor DIC limits this rapid response. Using microelectrodes, dual-pulse amplitude-modulated fluorometry, particle image velocimetry, and real time mass-spectrometry with the common scleractinian coral Favia veroni, the alga Gracilaria cornea, and the seagrass Halophila stipulacea, we show that this augmented photosynthesis is due to flow-driven enhancement of oxygen efflux from the organism to the water, which increases the affinity of the RuBisCO to CO2. No augmentation of photosynthesis was found in the absence of flow or when flow occurred, but the ambient concentration of oxygen was artificially elevated. We suggest that water motion should be considered a fundamental factor, equivalent to light and nutrients, in determining photosynthesis rates in marine benthic autotrophs.

Mass, Tali; Genin, Amatzia; Shavit, Uri; Grinstein, Mor; Tchernov, Dan

2010-01-01

301

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

302

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

303

Simplified kinetic schemes for oxy-fuel combustion  

Microsoft Academic Search

This work presents simplified kinetic schemes to be adopted in the CFD modeling of oxy-fuel combustion. Oxy-fuel combustion is an important technology to control CO 2 emissions. The reduction of nitrogen content during combustion makes easier the CO 2 capture for its successive storage. Flue gas recirculation can be adopted for the eventual temperature control. Moreover, oxygen rich combustion finds

A. Frassoldati; A. Cuoci; T. Faravelli; E. Ranzi; C. Candusso; D. Tolazzi

304

Partial combustion of electrical insulation fluids: Final report  

Microsoft Academic Search

Recurring fire incidents involving transformers have led to a desire to acquire information about the combustion products that may be generated not only in situations of complete combustion, but also in incidents when limited oxygen is present and combustion is incomplete or partial. This report details some results from investigations designed to identify the products of incomplete combustion of five

Claiborne

1987-01-01

305

Discharge-driven electric oxygen-iodine laser superlinear enhancement via increasing g0L.  

PubMed

The authors report the development of an electric oxygen-iodine laser with higher output using a larger product of gain and gain length, g0L. A factor of 4.4 increase in laser power output on the 1315 nm atomic iodine transition was achieved with a factor of 3 increase in gain length. I(2P1/2) is pumped using energy transferred from O2(a1?) produced by flowing a gas mixture of O2-He-NO through three coaxial geometry radio-frequency discharges. Continuous wave (CW) average total laser power of 481 W was extracted with g0L=0.042. PMID:22555687

Benavides, G F; Zimmerman, J W; Woodard, B S; Day, M T; King, D M; Carroll, D L; Palla, A D; Verdeyen, J T; Solomon, W C

2012-05-01

306

29 CFR 1910.104 - Oxygen.  

Code of Federal Regulations, 2013 CFR

...container to combustible liquid tank (feet) Distance from oxygen storage container to filling and vent...openings to combustible liquid tank (feet) 15 40. (ix) Flammable gas storage. (Such as compressed flammable gases,...

2013-07-01

307

Reduced oxygen concentration enhances conversion of embryonic stem cells to epiblast stem cells.  

PubMed

Recently, an additional type of pluripotent stem cell-line derived from mouse embryos has been established and termed epiblast stem cell (EpiSC), and is expected to be an important tool for studying the mechanisms of maintenance of pluripotency since they depend on basic fibroblast growth factor-MAPK and Activin A-Smad2/3 signaling to maintain pluripotency, unlike mouse embryonic stem cells (ESCs). Further, because of the similarities between mouse EpiSCs and human ESCs, EpiSCs are expected to be effective experimental models for human stem cell therapy. Recently, study for conversion from ESC state to EpiSC state or reversion from EpiSC state to ESC state has attracted interest since these techniques may lead to increasing the potential of pluripotent stem cells and our knowledge about their developmental status. In the present study, we find that a low oxygen concentration in culture environment accelerated, improved, and stabilized the EpiSC state of the converted cells from the ESC state using Oct4?PE-GFP transgenic ESCs. Induced EpiSCs (iEpiSCs) in hypoxia possess closer gene expression patterns to native EpiSCs, and bisulfite sequences for the promoter regions of Stella and Oct4 genes have elucidated that the iEpiSC gain EpiSC-specific methylation patterns in hypoxia. Our data provide evidence that oxygen concentration is an important factor for establishment of the EpiSC-specific state. PMID:21861689

Takehara, Toshiyuki; Teramura, Takeshi; Onodera, Yuta; Hamanishi, Chiaki; Fukuda, Kanji

2011-10-18

308

Heterogeneous Au-Pt nanostructures with enhanced catalytic activity toward oxygen reduction.  

PubMed

Heterogeneous Au-Pt nanostructures have been synthesized using a sacrificial template-based approach. Typically, monodispersed Au nanoparticles are prepared first, followed by Ag coating to form core-shell Au-Ag nanoparticles. Next, the galvanic replacement reaction between Ag shells and an aqueous H(2)PtCl(6) solution, whose chemical reaction can be described as 4Ag + PtCl(6)(2-)? Pt + 4AgCl + 2Cl(-), is carried out at room temperature. Pure Ag shell is transformed into a shell made of Ag/Pt alloy by galvanic replacement. The AgCl formed simultaneously roughens the surface of alloy Ag-Pt shells, which can be manipulated to create a porous Pt surface for oxygen reduction reaction. Finally, Ag and AgCl are removed from core-shell Au-Ag/Pt nanoparticles using bis(p-sulfonatophenyl)phenylphosphane dihydrate dipotassium salt to produce heterogeneous Au-Pt nanostructures. The heterogeneous Au-Pt nanostructures have displayed superior catalytic activity towards oxygen reduction in direct methanol fuel cells because of the electronic coupling effect between the inner-placed Au core and the Pt shell. PMID:22261896

Ye, Feng; Liu, Hui; Hu, Weiwei; Zhong, Junyu; Chen, Yingying; Cao, Hongbin; Yang, Jun

2012-01-20

309

Enhanced bioremediation utilizing hydrogen peroxide as a supplemental source of oxygen: A laboratory and field study. Final report, August 1987-November 1989  

SciTech Connect

Laboratory and field-scale studies were conducted to investigate the feasibility of using hydrogen peroxide as a supplemental source of oxygen for bioremediation of an aviation gasoline fuel spill. Field samples of aviation gasoline contaminated aquifer material were artificially enhanced with nutrients to promote microbiological degradation of fuel carbon in a laboratory column experiment. The rapid rate of hydrogen peroxide decomposition at 100 mg/l resulted in the production of oxygen gas. An oxygen mass balance indicated that approximately 44% and 45% of the influent oxygen was recovered in aqueous and gaseous phases, respectively. Reduced rates of oxygen consumption during this period indicated that microbial inhibition may have occurred. Ground-water data from the enhanced in-situ bioremediation pilot field study indicates that hydrogen peroxide successfully increased the concentration of available oxygen downgradient. In the study, however, it was observed that there was a measurable increase of oxygen in the soil-gas area where hydrogen peroxide was injected. This indicated that a significant fraction of hydrogen peroxide rapidly decomposed to oxygen gas and escaped into the unsaturated zone.

Huling, S.G.; Bledsoe, B.E.; White, M.V.

1990-02-01

310

Enhancing nitrogen use efficiency of cereal crops by optimizing temperature, moisture, balanced nutrients, and oxygen bioavailability  

Technology Transfer Automated Retrieval System (TEKTRAN)

Enhancement of nutrient use efficiency is imperative for increasing economic returns and reduction of environmental pollution caused by fertilization in crop production systems. In this paper, we have demonstrated at a given soil temperature and nitrogen (N) rate, N loss via ammonia (NH3) emission f...

311

Evidence for enhanced phosphorus regeneration from marine sediments overlain by oxygen depleted waters  

Microsoft Academic Search

Phosphorus regeneration and burial fluxes determined from in situ benthic flux chamber and solid phase measurements at sites on the Californian continental margin, Peruvian continental slope, North Carolina continental slope, and from the Santa Monica Basin, California are reported. Comparison of these sites indicates that O 2 -depleted bottomwaters enhance P regeneration from sediments, diminishing overall phosphorus burial efficiency. Based

Ellery Ingall; Richard Jahnke

1994-01-01

312

Environmental enhancement of creep crack growth in Inconel 718 by oxygen and water vapor  

Microsoft Academic Search

Inconel 718 alloy is widely used in high temperature applications. Because of its sensitivity to environmentally enhanced crack growth at high temperatures, its use has been limited to modest temperatures (i.e., below 973 K). To improve its performance and to better predict its service life, it is important to develop a better understanding of the processes of crack growth at

P. Valerio; M. Gao; R. P. Wei

1994-01-01

313

Combustion engineering  

SciTech Connect

This book is an introduction to combustion science. It discusses general aspects of combustion processes and deals with combustion of premixed mixtures and covers basic concepts of flame propagation, including the flame structure, burning velocity, flame stability, and the Rankine-Hugoniot equations. The book also deals with diffusive combustion, covering laminar and turbulent diffusion flames. Explosions and detonations, including ideal and nonideal explosions, and detonation wave structure are addressed. The determination of the burned gas states is discussed.

Ohtake, K.; Fujiwara, T.

1985-01-01

314

High temperature oxygen hazardous waste incinerator  

Microsoft Academic Search

The present invention is directed to a method and apparatus for incinerating hazardous wastes through the use of a high temperature incineration process. According to the method of the present invention, substantially pure oxygen is preheated by partial combustion with a fuel such as kerosene. The partial combustion of the oxygen preheats the oxygen to a temperature which is sufficient

Lanier

1982-01-01

315

Sunscreen enhancement of UV-induced reactive oxygen species in the skin.  

PubMed

The number of UV-induced (20 mJ cm(-2)) reactive oxygen species (ROS) generated in nucleated epidermis is dependent upon the length of time the UV filter octocrylene, octylmethoxycinnamate, or benzophenone-3 remains on the skin surface. Two-photon fluorescence images acquired immediately after application of each formulation (2 mg cm(-2)) to the skin surface show that the number of ROS produced is dramatically reduced relative to the skin-UV filter control. After each UV filter remains on the skin surface for t=20 min, the number of ROS generated increases, although it remains below the number generated in the control. By t=60 min, the filters generate ROS above the control. The data show that when all three of the UV filters penetrate into the nucleated layers, the level of ROS increases above that produced naturally by epidermal chromophores under UV illumination. PMID:17015167

Hanson, Kerry M; Gratton, Enrico; Bardeen, Christopher J

2006-07-06

316

Enhanced Surfactant Adsorption on Activated Carbon through Manipulation of Surface Oxygen Groups  

NASA Astrophysics Data System (ADS)

Passive energy storage is a necessary component for balancing the lifecycle budget with new forms of green energy. The work presented describes how surface oxygen groups (SOG) on granulated activated carbon have been manipulated using Nitric Acid in a controlled, stepwise fashion. The structure and surface functionality of the activated carbon samples were characterized using DRIFTS, Raman Spectroscopy and Porosimetry. Total surface area was found to increase proportionally with the removal of heteroatom material, exposing previously insulated active sites responsible for SOG attachment. Broad oxide peaks were deconvoluted and analyzed, allowing for absolute identification of evolving functionality at each oxidation stage. SOGs were maximized on the third oxidation cycle with the presence of conjugated aromatic, phenol, lactone, and carboxylic acid groups. FSN Zonyl nonionic was applied to all oxidized samples at various concentrations. Total adsorbed surfactant was quantified for each concentration / oxidation scheme using attenuated total reflection. The relative quantity and polarity of chemisorbed surfactant were qualitatively assessed for each equilibrium concentration.

Collins, John; Qu, Deyang; Foster, Michelle

2012-02-01

317

Bimetallic carbide nanocomposite enhanced Pt catalyst with high activity and stability for the oxygen reduction reaction.  

PubMed

Nanocomposites consisting of the bimetallic carbide Co(6)Mo(6)C(2) supported on graphitic carbon ((g)C) were synthesized in situ by an anion-exchange method for the first time. The Co(6)Mo(6)C(2)/(g)C nanocomposites were not only chemically stable but also electrochemically stable. The catalyst prepared by loading Pt nanoparticles onto Co(6)Mo(6)C(2)/(g)C was evaluated for the oxygen reduction reaction in acidic solution and showed superior activity and stability in comparison with commercial Pt/C. The higher mass activity of the Pt-Co(6)Mo(6)C(2)/(g)C catalyst indicated that less Pt would be required for the same performance, which in turn would reduce the cost of the fuel cell electrocatalyst. The method reported here will promote broader interest in the further development of other nanostructured materials for real-world applications. PMID:22263755

Ma, Xueming; Meng, Hui; Cai, Mei; Shen, Pei Kang

2012-01-20

318

Mild Combustion  

Microsoft Academic Search

The Mild Combustion is characterized by both an elevated temperature of reactants and low temperature increase in the combustion process. These features are the results of several technological demands coming from different application fields. This review paper aims to collect information which could be useful in understanding the fundamentals and applications of Mild Combustion. The information in this field are

Antonio Cavaliere; Mara de Joannon

2004-01-01

319

Redox cycling by motexafin gadolinium enhances cellular response to ionizing radiation by forming reactive oxygen species  

Microsoft Academic Search

Purpose: To examine the mechanism of radiation enhancement by motexafin gadolinium (Gd-Tex) in vitro.Methods and Materials: Oxidation of ascorbate and NADPH by Gd-Tex was evaluated in a neutral buffer. Growth inhibition of human uterine cancer cell line MES-SA was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) dye. Clonogenic assays were used to measure radiation response in MES-SA, A549 human lung carcinoma, E89,

Darren Magda; Cheryl Lepp; Nikolay Gerasimchuk; Intae Lee; Jonathan L Sessler; Alice Lin; John E Biaglow; Richard A Miller

2001-01-01

320

Emission assessment from full-scale co-combustion tests of binder- enhanced dRDF pellets and high sulfur coal at Argonne National Laboratory  

SciTech Connect

Argonne National Laboratory (ANL) and University of North Texas (UNT) research teams collected over 800 emissions and ash samples during the combustion of over 650 tons of binder enhanced densified refuse-drived fuel (b-dRDF) pellets with high sulfur coal in a spreader-stoker boiler at ANL. This full-scale test burn was conducted to validate predictions from laboratory and pilot scale test results that indicated substantial reductions of SO{sub 2}, NO{sub x} and CO{sub 2} in the flue gas, and the reduction of heavy metals and organics in the ash residue, when combusting the b-dRDF pellets with coal. Effects of varying fuel composition on performance of the boiler's spray-dryer/fabric filter emissions control system was also evaluated. This paper describes the b-dRDF pellet/coal cofiring tests, the emission and ash samples that were taken, the analyses that were conducted on these samples, and the final test results. 5 refs., 1 fig., 1 tab.

Ohlsson, O.O.; Livengood, C.D. (Argonne National Lab., IL (USA)); Daugherty, K.E. (University of North Texas, Denton, TX (USA))

1990-06-04

321

Microbial degradation and fate in the environment of methyl tert -butyl ether and related fuel oxygenates  

Microsoft Academic Search

Oxygenates, mainly methyl tert-butyl ether (MTBE), are commonly added to gasoline to enhance octane index and improve combustion efficiency. Other oxygenates used as gasoline additives are ethers such as ethyl tert-butyl ether (ETBE), tert-amyl methyl ether (TAME), and alcohols such as tert-butyl alcohol (TBA). As a result of its wide use, MTBE has been detected, mainly in the USA, in

F. Fayolle; J.-P. Vandecasteele; F. Monot

2001-01-01

322

Production of Oxygen  

NSDL National Science Digital Library

In this chemistry activity, learners use yeast and hydrogen peroxide to generate a gas (oxygen) and test some of its properties. This resource includes brief questions for learners to answer after the experiment. Use this activity to introduce learners to oxygen as well as combustion. Note: this activity involves an open flame.

House, The S.

2013-05-15

323

Improvement of islet function in a bioartificial pancreas by enhanced oxygen supply and growth hormone releasing hormone agonist.  

PubMed

Islet transplantation is a feasible therapeutic alternative for metabolically labile patients with type 1 diabetes. The primary therapeutic target is stable glycemic control and prevention of complications associated with diabetes by reconstitution of endogenous insulin secretion. However, critical shortage of donor organs, gradual loss in graft function over time, and chronic need for immunosuppression limit the indication for islet transplantation to a small group of patients. Here we present a promising approach to address these limitations by utilization of a macrochamber specially engineered for islet transplantation. The s.c. implantable device allows for controlled and adequate oxygen supply and provides immunological protection of donor islets against the host immune system. The minimally invasive implantable chamber normalized blood glucose in streptozotocin-induced diabetic rodents for up to 3 mo. Sufficient graft function depended on oxygen supply. Pretreatment with the growth hormone-releasing hormone (GHRH) agonist, JI-36, significantly enhanced graft function by improving glucose tolerance and increasing ?-cell insulin reserve in rats thereby allowing for a reduction of the islet mass required for metabolic control. As a result of hypervascularization of the tissue surrounding the device, no relevant delay in insulin response to glucose changes has been observed. Consequently, this system opens up a fundamental strategy for therapy of diabetes and may provide a promising avenue for future approaches to xenotransplantation. PMID:22393012

Ludwig, Barbara; Rotem, Avi; Schmid, Janine; Weir, Gordon C; Colton, Clark K; Brendel, Mathias D; Neufeld, Tova; Block, Norman L; Yavriyants, Karina; Steffen, Anja; Ludwig, Stefan; Chavakis, Triantafyllos; Reichel, Andreas; Azarov, Dimitri; Zimermann, Baruch; Maimon, Shiri; Balyura, Mariya; Rozenshtein, Tania; Shabtay, Noa; Vardi, Pnina; Bloch, Konstantin; de Vos, Paul; Schally, Andrew V; Bornstein, Stefan R; Barkai, Uriel

2012-03-05

324

Enhancement of oxygen vacancies and solar photocatalytic activity of zinc oxide by incorporation of nonmetal  

SciTech Connect

B-doped ZnO and N-doped ZnO powders have been synthesized by mechanochemical method and characterized by TG-DTA, XRD, SEM-EDX, XPS, UV-visible and photoluminescence (PL) spectra. X-ray diffraction data suggests the hexagonal wurtzite structure for modified ZnO crystallites and the incorporation of nonmetal expands the lattice constants of ZnO. The room temperature PL spectra suggest more number of oxygen vacancies exist in nonmetal-doped ZnO than that of undoped zinc oxide. XPS analysis shows the substitution of some of the O atoms of ZnO by nonmetal atoms. Solar photocatalytic activity of B-doped ZnO, N-doped ZnO and undoped ZnO was compared by means of oxidative photocatalytic degradation (PCD) of Bisphenol A (BPA). B-doped ZnO showed better solar PCD efficiency as compare to N-doped ZnO and undoped ZnO. The PCD of BPA follows first order reaction kinetics. The detail mechanism of PCD of Bisphenol A was proposed with the identification of intermediates such as hydroquinone, benzene-1,2,4-triol and 4-(2-hydroxypropan-2-yl) phenol. - Graphical Abstract: B-doped ZnO and N-doped ZnO synthesized by mechanochemical method were characterized by various techniques. Solar photocatalytic degradation of Bisphenol-A is in the order of B-ZnO>N-ZnO>ZnO. Highlights: Black-Right-Pointing-Pointer B-doped ZnO and N-doped ZnO powders have been synthesized by mechanochemical method. Black-Right-Pointing-Pointer PL spectra suggest oxygen vacancies are in order of B-doped ZnO>N-doped ZnO>ZnO. Black-Right-Pointing-Pointer Solar PCD efficiency is in order of B-doped ZnO>N-doped ZnO>ZnO for Bisphenol A.

Patil, Ashokrao B. [Department of Chemistry, University of Pune, Ganeshkhind, Pune 411007 (India); Patil, Kashinath R. [Center for Materials Characterization, National Chemical Laboratory, Pune 411008 (India); Pardeshi, Satish K., E-mail: skpar@chem.unipune.ac.in [Department of Chemistry, University of Pune, Ganeshkhind, Pune 411007 (India)

2011-12-15

325

Oxygen-diffusion limited metal combustions in Zr, Ti, and Fe foils: Time and angle-resolved x-ray diffraction studies  

Microsoft Academic Search

The transient phase and chemical transformations of diffusion controlled metal combustions in bulk Zr, Ti, and Fe foils have been investigated, in situ, using novel time- and angle-resolved x-ray diffraction (TARXD). The TARXD employs monochromatic synchrotron x-rays and a fast-rotating diffracted beam chopper resolving the diffraction image temporally in time-resolution of 45 s along the azimuth on a 2D pixel

Haoyan Wei; Choong-Shik Yoo; Jing-Yin Chen; Guoyin Shen

2012-01-01

326

Mathematical modeling of MSW combustion and SNCR in a full-scale municipal incinerator and effects of grate speed and oxygen-enriched atmospheres on operating conditions  

Microsoft Academic Search

The rising popularity of incineration of municipal solid waste (MSW) calls for detailed mathematical modeling and accurate prediction of pollutant emissions. In this paper, mathematical modeling methods for both solid and gaseous phases were employed to simulate the operation of a 450t\\/d MSW-burning incinerator to obtain detailed information on the flow and combustion characteristics in the furnace and to predict

Zengying Liang; Xiaoqian Ma

2010-01-01

327

Performance of coal-gasification-reheat combustion-turbine power cycles using dry cooling. Final report. [Texaco oxygen-blown gasifier and British Gas Corporation slagging gasifier  

Microsoft Academic Search

A study was conducted to explore the near-term performance potential of coal-gasification combined cycles that use reheat combustion turbines and dry cooling. The major finding is that these cycles can have coal-to-bus-bar efficiencies close to 40% if the components are properly matched. The study assumes that reheat gas turbines with inlet temperatures of about 2370°F could be developed. The addition

Horazak

1983-01-01

328

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 ...

329

Toward a Full Simulation of the Basic Oxygen Furnace: Deformation of the Bath Free Surface and Coupled Transfer Processes Associated with the Post-Combustion in the Gas Region  

NASA Astrophysics Data System (ADS)

The present article treats different phenomena taking place in a steelmaking converter through the development of two separate models. The first model describes the cavity produced at the free surface of the metal bath by the high-speed impinging oxygen jet. The model is based on a zonal approach, where gas compressibility effects are taken into account only in the high velocity jet region, while elsewhere the gas is treated as incompressible. The volume of fluid (VOF) method is employed to follow the deformation of the bath free surface. Calculations are presented for two- and three-phase systems and compared against experimental data obtained in a cold model experiment presented in the literature. The influence on the size and shape of the cavity of various parameters and models (including the jet inlet boundary conditions, the VOF advection scheme, and the turbulence model) is studied. Next, the model is used to simulate the interaction of a supersonic oxygen jet with the surface of a liquid steel bath in a pilot-scale converter. The second model concentrates on fluid flow, heat transfer, and the post-combustion reaction in the gas phase above the metal bath. The model uses the simple chemical reaction scheme approach to describe the transport of the chemical species and takes into account the consumption of oxygen by the bath and thermal radiative transfer. The model predictions are in reasonable agreement with measurements collected in a laboratory experiment and in a pilot-scale furnace.

Doh, Y.; Chapelle, P.; Jardy, A.; Djambazov, G.; Pericleous, K.; Ghazal, G.; Gardin, P.

2013-06-01

330

Combustion front propagation in underground coal gasification  

SciTech Connect

Reverse Combustion (RC) enhances coal seam permeability prior to Underground Coal Gasification. Understanding RC is necessary to improve its reliability and economics. A curved RC front propagation model is developed, then solved by high activation energy asymptotics. It explicitly incorporates extinction (stoichiometric and thermal) and tangential heat transport (THT) (convection and conduction). THT arises from variation in combustion front temperature caused by tangential variation in the oxidant gas flux to the channel surface. Front temperature depends only weakly on THT; front velocity is strongly affected, with heat loss slowing propagation. The front propagation speed displays a maximum with respect to gas flux. Combustion promoters speed front propagation; inhibitors slow front propagation. The propagation model is incorporated into 2-D simulations of RC channel evolution utilizing the boundary element method with cubic hermetian elements to solve the flow from gas injection wells through the coal to the convoluted, temporally evolving, channel surface, and through the channel to a gas production well. RC channel propagation is studied using 17 cm diameter subbituminous horizontally drilled coal cores. Sixteen experiments at pressures between 2000 and 3600 kPa, injected gas oxygen contents between 21% and 75%, and flows between 1 and 4 standard liters per minute are described. Similarity analysis led to scaling-down of large RC ({approx}1 m) to laboratory scale ({approx}5 cm). Propagation velocity shows a strong synergistic increase at high levels of oxygen, pressure, and gas flow. Char combustion is observed, leaving ash-filled, irregularly shaped channels. Cracks are observed to penetrate the char zone surrounding the channel cores. 69 refs., 54 figs., 4 tabs.

Dobbs, R.L. II; Krantz, W.B.

1990-10-01

331

High thermal sensitivity of blood enhances oxygen delivery in the high-flying bar-headed goose.  

PubMed

The bar-headed goose (Anser indicus) crosses the Himalaya twice a year at altitudes where oxygen (O2) levels are less than half those at sea level and temperatures are below -20°C. Although it has been known for over three decades that the major hemoglobin (Hb) component of bar-headed geese has an increased affinity for O2, enhancing O2 uptake, the effects of temperature and interactions between temperature and pH on bar-headed goose Hb-O2 affinity have not previously been determined. An increase in breathing of the hypoxic and extremely cold air experienced by a bar-headed goose at altitude (due to the enhanced hypoxic ventilatory response in this species) could result in both reduced temperature and reduced levels of CO2 at the blood-gas interface in the lungs, enhancing O2 loading. In addition, given the strenuous nature of flapping flight, particularly in thin air, blood leaving the exercising muscle should be warm and acidotic, facilitating O2 unloading. To explore the possibility that features of blood biochemistry in this species could further enhance O2 delivery, we determined the P50 (the partial pressure of O2 at which Hb is 50% saturated) of whole blood from bar-headed geese under conditions of varying temperature and [CO2]. We found that blood-O2 affinity was highly temperature sensitive in bar-headed geese compared with other birds and mammals. Based on our analysis, temperature and pH effects acting on blood-O2 affinity (cold alkalotic lungs and warm acidotic muscle) could increase O2 delivery by twofold during sustained flapping flight at high altitudes compared with what would be delivered by blood at constant temperature and pH. PMID:23470665

Meir, Jessica U; Milsom, William K

2013-03-07

332

Reactive oxygen intermediates produced by photosynthetic electron transport are enhanced in short-day grown plants.  

PubMed

Leaves of tobacco plants grown in short days (8h light) generate more reactive oxygen species in the light than leaves of plants grown in long days (16h light). A two fold higher level of superoxide production was observed even in isolated thylakoids from short day plants. By using specific inhibitors of photosystem II and of the cytochrome b(6)f complex, the site of O(2) reduction could be assigned to photosystem I. The higher rate of O(2) reduction led to the formation of a higher proton gradient in thylakoids from short day plants. In the presence of an uncoupler, the differences in O(2) reduction between thylakoids from short day and long day plants were abolished. The pigment content and the protein content of the major protein complexes of the photosynthetic electron transport chain were unaffected by the growth condition. Addition of NADPH, but not of NADH, to coupled thylakoids from long day plants raised the level of superoxide production to the same level as observed in thylakoids from short day plants. The hypothesis is put forward that the binding of an unknown protein permits the higher rate of pseudocyclic electron flow in thylakoids from short-day grown plants and that this putative protein plays an important role in changing the proportions of linear, cyclic and pseudocyclic electron transport in favour of pseudocyclic electron transport. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial. PMID:22172734

Michelet, Laure; Krieger-Liszkay, Anja

2011-12-07

333

Enhanced oxygen unloading by an interdimerically crosslinked hemoglobin in an isolated perfused rabbit heart.  

PubMed Central

Coronary perfusion has shown that an intramolecularly crosslinked hemoglobin (Hb) with a very low affinity for O2 (Hb crosslinked covalently between the beta chains with 2-nor-2-formylpyridoxal 5'-phosphate, HbXL) has several advantages over ordinary Hb. As predicted from in vitro oxygenation curves, much more O2 was unloaded to the heart at three different heart rates, at two perfusion rates, and when the perfusate was equilibrated with 25% as well as 95% O2. In all cases, the improved O2 unloading occurred at higher tissue O2 pressures than with normal Hb. The greater O2 consumption with HbXL was accompanied by better mechanical performance because, after 90 min of perfusion, the HbXL-perfused hearts maintained two-thirds of their original contractility (dp/dt), while that of the Hb-perfused hearts had declined to one-fifth. A special advantage of HbXL is its ability to unload significant amounts of O2 even at low temperature (10 degrees C), in contrast to whole blood. This should make it useful for supporting aerobic metabolism during low-temperature cardioplegia in cardiac surgery and for organ preservation.

Benesch, R; Triner, L; Benesch, R E; Kwong, S; Verosky, M

1984-01-01

334

A biofilm enhanced miniature microbial fuel cell using Shewanella oneidensis DSP10 and oxygen reduction cathodes.  

PubMed

A miniature-microbial fuel cell (mini-MFC, chamber volume: 1.2 mL) was used to monitor biofilm development from a pure culture of Shewanella oneidensis DSP10 on graphite felt (GF) under minimal nutrient conditions. ESEM evidence of biofilm formation on GF is supported by substantial power density (per device cross-section) from the mini-MFC when using an acellular minimal media anolyte (1500 mW/m2). These experiments demonstrate that power density per volume for a biofilm flow reactor MFC should be calculated using the anode chamber volume alone (250W/m3), rather than with the full anolyte volume. Two oxygen reduction cathodes (uncoated GF or a Pt/vulcanized carbon coating on GF) were also compared to a cathode using uncoated GF and a 50mM ferricyanide catholyte solution. The Pt/C-GF (2-4% Pt by mass) electrodes with liquid cultures of DSP10 produced one order of magnitude larger power density (150W/m3) than bare graphite felt (12W/m3) in this design. These advances are some of the required modifications to enable the mini-MFC to be used in real-time, long-term environmental power generating situations. PMID:16939710

Biffinger, Justin C; Pietron, Jeremy; Ray, Ricky; Little, Brenda; Ringeisen, Bradley R

2006-08-30

335

Enhancement of oxygen vacancies and solar photocatalytic activity of zinc oxide by incorporation of nonmetal  

NASA Astrophysics Data System (ADS)

B-doped ZnO and N-doped ZnO powders have been synthesized by mechanochemical method and characterized by TG-DTA, XRD, SEM-EDX, XPS, UV-visible and photoluminescence (PL) spectra. X-ray diffraction data suggests the hexagonal wurtzite structure for modified ZnO crystallites and the incorporation of nonmetal expands the lattice constants of ZnO. The room temperature PL spectra suggest more number of oxygen vacancies exist in nonmetal-doped ZnO than that of undoped zinc oxide. XPS analysis shows the substitution of some of the O atoms of ZnO by nonmetal atoms. Solar photocatalytic activity of B-doped ZnO, N-doped ZnO and undoped ZnO was compared by means of oxidative photocatalytic degradation (PCD) of Bisphenol A (BPA). B-doped ZnO showed better solar PCD efficiency as compare to N-doped ZnO and undoped ZnO. The PCD of BPA follows first order reaction kinetics. The detail mechanism of PCD of Bisphenol A was proposed with the identification of intermediates such as hydroquinone, benzene-1,2,4-triol and 4-(2-hydroxypropan-2-yl) phenol.

Patil, Ashokrao B.; Patil, Kashinath R.; Pardeshi, Satish K.

2011-12-01

336

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

337

N-doped P25 TiO2-amorphous Al2O3 composites: one-step solution combustion preparation and enhanced visible-light photocatalytic activity.  

PubMed

Nitrogen-doped Degussa P25 TiO2-amorphous Al2O3 composites were prepared via facile solution combustion. The composites were characterised using X-ray diffraction, high-resolution transmission microscopy, scanning electron microscopy, nitrogen adsorption-desorption measurements, X-ray photoelectron spectroscopy, UV-vis light-diffusion reflectance spectrometry (DRS), zeta-potential measurements, and photoluminescence spectroscopy. The DRS results showed that TiO2 and amorphous Al2O3 exhibited absorption in the UV region. However, the Al2O3/TiO2 composite exhibited visible-light absorption, which was attributed to N-doping during high-temperature combustion and to alterations in the electronic structure of Ti species induced by the addition of Al. The optimal molar ratio of TiO2 to Al2O3 was 1.5:1, and this composite exhibited a large specific surface area of 152 m2/g, surface positive charges, and enhanced photocatalytic activity. These characteristics enhanced the degradation rate of anionic methylene orange, which was 43.6 times greater than that of pure P25 TiO2. The high visible-light photocatalytic activity was attributed to synthetic effects between amorphous Al2O3 and TiO2, low recombination efficiency of photo-excited electrons and holes, N-doping, and a large specific surface area. Experiments that involved radical scavengers indicated that OH and O2- were the main reactive species. A potential photocatalytic mechanism was also proposed. PMID:23021102

Li, Fa-tang; Zhao, Ye; Hao, Ying-juan; Wang, Xiao-jing; Liu, Rui-hong; Zhao, Di-shun; Chen, Dai-mei

2012-08-14

338

Laser irradiation of mouse spermatozoa enhances in-vitro fertilization and Ca2+ uptake via reactive oxygen species  

NASA Astrophysics Data System (ADS)

630 nm He-Ne laser irradiation was found to have a profound influence on Ca2+ uptake in mouse spermatozoa and the fertilizing potential of these cells. Laser irradiation affected mainly the mitochondrial Ca2+ transport mechanisms. Furthermore, the effect of light was found to be Ca2+-dependent. We demonstrate that reactive oxygen species (ROS) are involved in the cascade of biochemical events evoked by laser irradiation. A causal association between laser irradiation, ROS generation, and sperm function was indicated by studies with ROS scavengers, superoxide dismutase (SOD) and catalase, and exogenous hydrogen peroxide. SOD treatment resulted in increased Ca2+ uptake and in enhanced fertilization rate. Catalase treatment impaired the light-induced stimulation in Ca2+ uptake and fertilization rate. Exogenous hydrogen peroxide was found to enhance Ca2+ uptake in mouse spermatozoa and the fertilizing capability of these cells in a dose-dependent manner. These results suggest that the effect of 630 nm He-Ne laser irradiation is mediated through the generation of hydrogen peroxide by the spermatozoa and that this effect plays a significant role in the augmentation of the sperm cells' capability to fertilize metaphase II-arrested eggs in-vitro.

Cohen, Natalie; Lubart, Rachel; Rubinstein, Sara; Breitbart, Haim

1996-11-01

339

Recombinant gene which enhances the ability of fish to tolerate low dissolved oxygen stress and the use thereof  

US Patent & Trademark Office Database

The invention discloses a recombinant gene which enhances the ability of fish to tolerate low dissolved oxygen (DO) stress and the use thereof. Carp .beta.-actin gene promoter is used as a promoter and Vitreoscilla hemoglobin gene is used as a target gene, so as to construct the recombinant Vitreoscilla hemoglobin gene driven by carp .beta.-actin promoter. The modeling organism zebrafish is used as the research object, and the recombinant gene is microinjected into zygotes of zebrafish. After PCR screening and 156 h low DO stress test, transgenic fish are obtained with a survival rate of 92%, which is significantly different from the survival rate of 65% of the control fish group. The vhb transgenic zebrafish obtain hypoxia tolerance. When the recombinant gene is applied to the economically farmed species, i.e., blunt snout bream (Megalobrama amblycephala) and common carp (Cyprinus carpio L.), it enhances their hypoxia tolerance as well. Such genetically improved breeding technique may be widely used for breeding new excellent farmed species with the hypoxia tolerance.

2013-10-01

340

Activating mutations in protein tyrosine phosphatase Ptpn11 (Shp2) enhance reactive oxygen species production that contributes to myeloproliferative disorder.  

PubMed

Gain of function (GOF) mutations in protein tyrosine phosphatase Ptpn11 have been identified in childhood leukemias, and these mutations are sufficient to drive the development of myeloproliferative disorder and malignant leukemias in mice. However, the molecular mechanisms by which Ptpn11 mutations induce these malignancies are not completely understood. Here we report that Ptpn11 GOF mutations cause cytokine hypersensitivity in hematopoietic cells partly by enhancing the production of reactive oxygen species (ROS). GOF mutations D61G or E76K in Ptpn11 increased ROS levels in myeloid progenitors but not in hematopoietic stem cells. Increased ROS enhanced cellular responses to cytokines by promoting cytokine signaling. Treatment with an antioxidant partially corrected cytokine hypersensitivity in Ptpn11 mutant progenitors. Further analyses demonstrated that Ptpn11 mutations increased mitochondrial aerobic metabolism by interacting with a novel substrate in the mitochondria. This study provides new insights into the pathogenic effects of GOF mutations of Ptpn11 and implies that antioxidants may have a therapeutic benefit for the leukemic patients with these mutations. PMID:23675459

Xu, Dan; Zheng, Hong; Yu, Wen-Mei; Qu, Cheng-Kui

2013-05-10

341

Activating Mutations in Protein Tyrosine Phosphatase Ptpn11 (Shp2) Enhance Reactive Oxygen Species Production That Contributes to Myeloproliferative Disorder  

PubMed Central

Gain of function (GOF) mutations in protein tyrosine phosphatase Ptpn11 have been identified in childhood leukemias, and these mutations are sufficient to drive the development of myeloproliferative disorder and malignant leukemias in mice. However, the molecular mechanisms by which Ptpn11 mutations induce these malignancies are not completely understood. Here we report that Ptpn11 GOF mutations cause cytokine hypersensitivity in hematopoietic cells partly by enhancing the production of reactive oxygen species (ROS). GOF mutations D61G or E76K in Ptpn11 increased ROS levels in myeloid progenitors but not in hematopoietic stem cells. Increased ROS enhanced cellular responses to cytokines by promoting cytokine signaling. Treatment with an antioxidant partially corrected cytokine hypersensitivity in Ptpn11 mutant progenitors. Further analyses demonstrated that Ptpn11 mutations increased mitochondrial aerobic metabolism by interacting with a novel substrate in the mitochondria. This study provides new insights into the pathogenic effects of GOF mutations of Ptpn11 and implies that antioxidants may have a therapeutic benefit for the leukemic patients with these mutations.

Yu, Wen-Mei; Qu, Cheng-Kui

2013-01-01

342

Enhanced combustion of fossil-fuel particles and droplets in oscillating flow. Annual technical report, 1 September 1978-31 August 1979  

Microsoft Academic Search

The objective of this research is to determine the effect of oscillating flow on the rates of combustion of fossil fuel particles or droplets. Under certain conditions, an oscillatory (pulsating) flow may produce significantly increased rates of burning of fuel particles or droplets and thus provide more effective fuel utilization, with reduced excess air and improved combustion efficiency. The combustion

F. A. Lyman; J. S. Sabnis

1979-01-01

343

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

344

Enhancement of ?-opioid receptor desensitization by nitric oxide in rat locus coeruleus neurons: involvement of reactive oxygen species.  

PubMed

It has previously been shown that nitric oxide (NO) synthase is involved in the development of opioid tolerance. The aim of the present work was to study the effect of NO on ?-opioid receptor (MOR) desensitization. Furthermore, we explored the possible role of reactive oxygen species (ROS) in this effect. Single-unit extracellular and whole-cell patch-clamp recordings were performed on locus coeruleus (LC) neurons from rat brain slices. Perfusion with high concentrations of Met(5)-enkephalin (ME) caused a concentration-related reduction of opioid effect, reflecting the induction of homologous MOR desensitization. The NO donors sodium nitroprusside and diethylamine NONOate markedly enhanced the ME-induced MOR desensitization, although the acute effect of ME on K(+) conductance was not affected by sodium nitroprusside. Continuous perfusion with the antioxidants melatonin, trolox, 21-[4-(2,6-di-1-pyrrolidinyl-4-pyrrimidinyl)-1-piperazinyl]-pregna-1,4,9(11)-triene-3,20-dione(Z)-2-butenedioate (U74389G), and diethyldithiocarbamate prevented the effect of sodium nitroprusside on MOR desensitization, but they did not themselves alter the desensitization. Like sodium nitroprusside, the ROS-generating molecule H(2)O(2) enhanced MOR desensitization induced by ME. However, ?(2)-adrenoceptor desensitization induced by noradrenaline was not modified by H(2)O(2), suggesting a selective action of ROS on MOR. Our results suggest that elevated levels of NO, which may be reached in pathological processes, enhance homologous desensitization of MOR in the LC, probably through a mechanism involving ROS generation. PMID:22593094

Llorente, J; Santamarta, M T; Henderson, G; Pineda, J

2012-05-16

345

Modeling of Laser-Induced Metal Combustion  

SciTech Connect

Experiments involving the interaction of a high-power laser beam with metal targets demonstrate that combustion plays an important role. This process depends on reactions within an oxide layer, together with oxygenation and removal of this layer by the wind. We present an analytical model of laser-induced combustion. The model predicts the threshold for initiation of combustion, the growth of the combustion layer with time, and the threshold for self-supported combustion. Solutions are compared with detailed numerical modeling as benchmarked by laboratory experiments.

Boley, C D; Rubenchik, A M

2008-02-20

346

Combustion processes for carbon capture  

Microsoft Academic Search

A review of the technologies for coal-based power generation closest to commercial application involving carbon capture is presented. Carbon capture and storage (CCS) developments are primarily adaptations of conventional combustion systems, with additional unit operations such as bulk oxygen supply, CO2 capture by sorbents, CO2 compression, and storage. They use pulverized coal combustion in entrained flow—the dominant current technology for

Terry F. Wall

2007-01-01

347

Esterified dendritic TAM radicals with very high stability and enhanced oxygen sensitivity.  

PubMed

In this work, we have developed a new class of dendritic TAM radicals (TG, TdG, and dTdG) through a convergent method based on the TAM core CT-03 or its deuterated analogue dCT-03 and trifurcated Newkome-type monomer. Among these radicals, dTdG exhibits the best EPR properties with sharpest EPR singlet and highest O(2) sensitivity due to deuteration of both the ester linker groups and the TAM core CT-03. Like the previous dendritic TAM radicals, these new compounds also show extremely high stability toward various reactive species owing to the dendritic encapsulation. The highly charged nature of these molecules resulting from nine carboxylate groups prevents concentration-dependent EPR line broadening at physiological pH. Furthermore, we demonstrate that these TAM radicals can be easily derivatized (e.g., PEGylation) at the nine carboxylate groups and the resulting PEGylated analogue dTdG-PEG completely inhibits the albumin binding, thereby enhancing suitability for in vivo applications. These new dendritic TAM radicals show great potential for in vivo EPR oximetric applications and provide insights on approaches to develop improved and targeted EPR oximetric probes for biomedical applications. PMID:23343531

Song, Yuguang; Liu, Yangping; Hemann, Craig; Villamena, Frederick A; Zweier, Jay L

2013-02-06

348

Computational Combustion  

SciTech Connect

Progress in the field of computational combustion over the past 50 years is reviewed. Particular attention is given to those classes of models that are common to most system modeling efforts, including fluid dynamics, chemical kinetics, liquid sprays, and turbulent flame models. The developments in combustion modeling are placed into the time-dependent context of the accompanying exponential growth in computer capabilities and Moore's Law. Superimposed on this steady growth, the occasional sudden advances in modeling capabilities are identified and their impacts are discussed. Integration of submodels into system models for spark ignition, diesel and homogeneous charge, compression ignition engines, surface and catalytic combustion, pulse combustion, and detonations are described. Finally, the current state of combustion modeling is illustrated by descriptions of a very large jet lifted 3D turbulent hydrogen flame with direct numerical simulation and 3D large eddy simulations of practical gas burner combustion devices.

Westbrook, C K; Mizobuchi, Y; Poinsot, T J; Smith, P J; Warnatz, J

2004-08-26

349

Utilization of oxygen-enriched air in diesel engines: Fundamental considerations  

SciTech Connect

Utilization of oxygen-enriched air in diesel engines holds potential for low exhaust smoke and particulate emissions. The majority of the oxygen-enriched-air combustion-related studies so far are experimental in nature, where the observed results are understood on an overall basis. This paper deals with the fundamental considerations associated with the oxygen-enriched air-fuel combustion process to enhance understanding of the concept. The increase in adiabatic flame temperature, the composition of exhaust gases at equilibrium, and also the changes in thermodynamic and transport properties due to oxygen-enrichment of standard intake air are computed. The effects of oxygen-enrichment on fuel evaporation rate, ignition delay, and premixed burnt fraction are also evaluated. Appropriate changes in the ignition delay correlation to reflect the effects of oxygen-enrichment are proposed. The notion of oxygen-enrichment of standard intake air as being akin to leaning of the fuel-air mixture is refuted on the basis of the fundamentally different requirements for the oxygen-enriched combustion process.

Lahiri, D.; Mehta, P.S. [Indian Inst. of Tech., Madras (India); Poola, R.B.; Sekar, R. [Argonne National Lab., IL (United States)

1997-09-01

350

Combustion heater  

Microsoft Academic Search

A wood burning combustion heater comprises a combustion chamber for long logs arranged to burn down from one end to the other in cigar-like fashion, an after-burner tube arrayed above and essentially parallel to the elongated logs with the air and burned gasses following an S-shaped path through the combustion chamber and out through the exhaust tube, an after-burner within

Kalenian

1980-01-01

351

Overexpression of genes encoding glycolytic enzymes in Corynebacterium glutamicum enhances glucose metabolism and alanine production under oxygen deprivation conditions.  

PubMed

We previously reported that Corynebacterium glutamicum strain ?ldhA?ppc+alaD+gapA, overexpressing glyceraldehyde-3-phosphate dehydrogenase-encoding gapA, shows significantly improved glucose consumption and alanine formation under oxygen deprivation conditions (T. Jojima, M. Fujii, E. Mori, M. Inui, and H. Yukawa, Appl. Microbiol. Biotechnol. 87:159-165, 2010). In this study, we employ stepwise overexpression and chromosomal integration of a total of four genes encoding glycolytic enzymes (herein referred to as glycolytic genes) to demonstrate further successive improvements in C. glutamicum glucose metabolism under oxygen deprivation. In addition to gapA, overexpressing pyruvate kinase-encoding pyk and phosphofructokinase-encoding pfk enabled strain GLY2/pCRD500 to realize respective 13% and 20% improved rates of glucose consumption and alanine formation compared to GLY1/pCRD500. Subsequent overexpression of glucose-6-phosphate isomerase-encoding gpi in strain GLY3/pCRD500 further improved its glucose metabolism. Notably, both alanine productivity and yield increased after each overexpression step. After 48 h of incubation, GLY3/pCRD500 produced 2,430 mM alanine at a yield of 91.8%. This was 6.4-fold higher productivity than that of the wild-type strain. Intracellular metabolite analysis showed that gapA overexpression led to a decreased concentration of metabolites upstream of glyceraldehyde-3-phosphate dehydrogenase, suggesting that the overexpression resolved a bottleneck in glycolysis. Changing ratios of the extracellular metabolites by overexpression of glycolytic genes resulted in reduction of the intracellular NADH/NAD(+) ratio, which also plays an important role on the improvement of glucose consumption. Enhanced alanine dehydrogenase activity using a high-copy-number plasmid further accelerated the overall alanine productivity. Increase in glycolytic enzyme activities is a promising approach to make drastic progress in growth-arrested bioprocesses. PMID:22504802

Yamamoto, Shogo; Gunji, Wataru; Suzuki, Hiroaki; Toda, Hiroshi; Suda, Masako; Jojima, Toru; Inui, Masayuki; Yukawa, Hideaki

2012-04-13

352

Nonlinear enhancement of oxygen evolution in thylakoid membranes: modeling the effect of light intensity and beta-cyclodextrin concentration.  

PubMed

Electron transport through photosystem II, measured as oxygen evolution (OE), was investigated in isolated thylakoid membranes treated with beta-cyclodextrin (beta-CD, a cyclic oligosaccharide constituted of seven alpha-d-glucose residues linked by alpha-1,4 glycosidic bonds) and irradiated with white light of variable intensity. First, we found that the light-response curves of oxygen evolution are well fitted with a hyperbolic function, the shape of which is not affected by the beta-CD concentration. Second, we showed that under conditions of irradiation with white light of saturating intensity ( approximately 5000 mumol of photons/m(2).s) beta-CD enhances the oxygen evolution in the thylakoid membranes according to a sigmoid function displaying a sharp inflection point, or transition. Unexpectedely, this beta-CD effect is not observed at irradiances of less than approximately 300 mumol of photons/m(2).s. We attempted a theoretical analysis of the combined effect of irradiance and beta-CD concentration on oxygen evolution (OE(th)). For this purpose, the effect of irradiance (I) was modeled with a hyperbola (i) and the beta-CD concentration (C) contribution with a Hill equation, that is, a sigmoid function (ii). The mathematical simulations generated the following general expressions: (i) OE(th) = [OE(max)(0) G(1)(C)]I/[L(1/2)(0) G(2)(C) + I] and (ii) G(i)()(C) = 1 + p[C(n)()/(K(1/2)(n)() + C(n)())], where OE(max)(0) is the OE maximum (OE(max)) in the absence of beta-CD, L(1/2)(0) is the photon flux density giving OE(max)/2 in the absence of beta-CD, G(1)(C) or G(2)(C) is obtained from G(i)()(C) where i is 1 or 2, n is the Hill coefficient, p is a parameter to account for the beta-CD-mediated maximum OE increase, and K(1/2) is the beta-CD concentration giving half-maximal OE activity. The results of the calculations yielded the expression (iii) OE(th) = 151[1 + 3.3C(4.8)/(13.1(4.8) + C(4.8))]I/{97.5[1 + 5.2C(7.8)/(14.8(7.8) + C(7.8))] + I} which agrees well with the experimental data for a broad range of I and C. Note that, for C = 0, eq iii reverts to the light-response curve of oxygen evolution in the absence of beta-CD. We conclude that eq iii is a good approximation of the combined effect of irradiance and beta-CD concentration, meaning that the model has a significant value for predicting the outcome of associated photochemical and biochemical reactions. PMID:16852855

Fragata, Mário; Dudekula, Subhan

2005-08-01

353

A novel strategy of enhanced glutathione production in high cell density cultivation of Candida utilis—Cysteine addition combined with dissolved oxygen controlling  

Microsoft Academic Search

Effects of dissolved oxygen (DO) concentration on glutathione (GSH) production and cysteine oxidation were investigated in high cell density cultivation of Candida utilis. Lower DO concentration favors cysteine absorption but retards GSH production. Higher DO promotes GSH production but accelerates cysteine oxidation in the broth. A two-step DO control strategy was developed and compared for the potential in enhancing GSH

Guo-Bin Liang; Guo-Cheng Du; Jian Chen

2008-01-01

354

Enhancement of optical absorption by modulation of the oxygen flow of TiO2 films deposited by reactive sputtering  

NASA Astrophysics Data System (ADS)

Oxygen-deficient TiO2 films with enhanced visible and near-infrared optical absorption have been deposited by reactive sputtering using a planar diode radio frequency magnetron configuration. It is observed that the increase in the absorption coefficient is more effective when the O2 gas supply is periodically interrupted rather than by a decrease of the partial O2 gas pressure in the deposition plasma. The optical absorption coefficient at 1.5 eV increases from about 1 × 102 cm-1 to more than 4 × 103 cm-1 as a result of the gas flow discontinuity. A red-shift of ~0.24 eV in the optical absorption edge is also observed. High resolution transmission electron microscopy with composition analysis shows that the films present a dense columnar morphology, with estimated mean column width of 40 nm. Moreover, the interruptions of the O2 gas flow do not produce detectable variations in the film composition along its growing direction. X-ray diffraction and micro-Raman experiments indicate the presence of the TiO2 anatase, rutile, and brookite phases. The anatase phase is dominant, with a slight increment of the rutile and brookite phases in films deposited under discontinued O2 gas flow. The increase of optical absorption in the visible and near-infrared regions has been attributed to a high density of defects in the TiO2 films, which is consistent with density functional theory calculations that place oxygen-related vacancy states in the upper third of the optical bandgap. The electronic structure calculation results, along with the adopted deposition method and experimental data, have been used to propose a mechanism to explain the formation of the observed oxygen-related defects in TiO2 thin films. The observed increase in sub-bandgap absorption and the modeling of the corresponding changes in the electronic structure are potentially useful concerning the optimization of efficiency of the photocatalytic activity and the magnetic doping of TiO2 films.

Pereira, André L. J.; Lisboa Filho, Paulo N.; Acuña, Javier; Brandt, Iuri S.; Pasa, André A.; Zanatta, Antonio R.; Vilcarromero, Johnny; Beltrán, Armando; Dias da Silva, José H.

2012-06-01

355

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

356

Aging Enhances the Production of Reactive Oxygen Species and Bactericidal Activity in Peritoneal Macrophages by Upregulating Classical Activation Pathways  

SciTech Connect

Maintenance of macrophages in their basal state and their rapid activation in response to pathogen detection are central to the innate immune system, acting to limit nonspecific oxidative damage and promote pathogen killing following infection. To identify possible age-related alterations in macrophage function, we have assayed the function of peritoneal macrophages from young (3?4 months) and aged (14?15 months) Balb/c mice. In agreement with prior suggestions, we observe age-dependent increases in the extent of recruitment of macrophages into the peritoneum, as well as ex vivo functional changes involving enhanced nitric oxide production under resting conditions that contribute to a reduction in the time needed for full activation of senescent macrophages following exposure to lipopolysaccharides (LPS). Further, we observe enhanced bactericidal activity following Salmonella uptake by macrophages isolated from aged Balb/c mice in comparison with those isolated from young animals. Pathways responsible for observed phenotypic changes were interrogated using tandem mass spectrometry, which identified age-dependent increases in levels of proteins linked to immune cell pathways under basal conditions and following LPS activation. Immune pathways upregulated in macrophages isolated from aged mice include proteins critical to the formation of the immunoproteasome. Detection of these latter proteins is dramatically enhanced following LPS exposure for macrophages isolated from aged animals; in comparison, the identification of immunoproteasome subunits is insensitive to LPS exposure for macrophages isolated from young animals. Consistent with observed global changes in the proteome, quantitative proteomic measurements indicate that there are age-dependent abundance changes involving specific proteins linked to immune cell function under basal conditions. LPS exposure selectively increases the levels of many proteins involved in immune cell function in aged Balb/c mice. Collectively, these results indicate that macrophages isolated from old mice are in a preactivated state that enhances their sensitivities to LPS exposure. The hyper-responsive activation of macrophages in aged animals may act to minimize infection by general bacterial threats that arise due to age-dependent declines in adaptive immunity. However, this hypersensitivity and the associated increase in the level of formation of reactive oxygen species are likely to contribute to observed age-dependent increases in the level of oxidative damage that underlie many diseases of the elderly.

Smallwood, Heather S.; Lopez-Ferrer, Daniel; Squier, Thomas C.

2011-10-07

357

Enhanced growth and recombinant protein production of Escherichia coli by a perfluorinated oxygen carrier in miniaturized fed-batch cultures  

Microsoft Academic Search

Background  Liquid perfluorochemicals (PFCs) are interesting oxygen carriers in medicine and biotechnology with a high solubility for\\u000a oxygen. They have been repeatedly used for improving oxygen transfer into prokaryotic and eukaryotic cell cultures, however\\u000a their application is still limited. Here we show the great benefit of air\\/oxygen saturated perfluorodecalin (PFD) for high\\u000a cell density cultivation of Escherichia coli in microwell plates

Maciej Pilarek; Julia Glazyrina; Peter Neubauer

2011-01-01

358

Development of nanoparticle applications in cell imaging, bioassay and reactive oxygen species detection based on surface-enhanced raman spectroscopy  

NASA Astrophysics Data System (ADS)

Surface-enhanced Raman scattering (SERS) has been developed over forty years with a wide variety of applications. Signals enhanced from single molecule absorbed on the surface of metallic nanoparticles can be up to 14-order-of-magnitude. This is due to the resonance between the optical field and surface plasmon of the metal substrate. Nanoshells have been chosen as substrates since they do not need to pre-aggregate due to their tunable optical property. We developed Raman imaging system by incorporating functionalized nanoshells, cells and SERS. Nanoshells have been coated with different self-assembled monolayers containing poly(ethylene glycol) (PEG) molecules. Probes have been designed by coating nanoshells with Raman active PEG molecules and delivered into macrophage cells. The imaging technique requires less preparation and provides the information of nanoshells in semi-quantitative way in vitro. We developed half-sandwich bioassay by detecting low volume of antigens on nitrocellulose membrane, detected by SERS. Antibodies were grafted to the surface of nanoshells and were conjugated to the antigens on the nitrocellulose membrane for detection. Raman active PEGs were conjugated onto the metal substrate for recognition and quantification. The benefits of this assay are that it is faster, easier to execute and requires less volume of antigen to conjugate onto the substrate. We also developed reactive oxygen species (ROS) sensors by incubating PEGs and either 4-nitrobenzenethiol (4-NBT) or 4-mercaptophenol (4-MP) on the surface of nanoshells. By analyzing the changes of SERS spectrum, the production of hydroxyl radicals produced in the Fenton reaction can be tracked in low concentrations. The sensors were designed to track ROS production within cells when they are under oxidative stress. The methods developed in this thesis are versatile, and can be broadly applied to the study of different subtracts, such as gold colloid.

Huang, Yiming

359

Combustion process  

SciTech Connect

A combustion catalyst containing both manganese and antimony in a temperature range of above about 1260/sup 0/ F. has been found to result in unexpactedly high CO/sub 2//CO ratios in the regenerator off-gas when CO is combusted.

McKay, D.L.

1984-07-03

360

Transient combustion in hybrid rockets  

NASA Astrophysics Data System (ADS)

Hybrid rockets regained interest recently as an alternative chemical propulsion system due to their advantages over the solid and liquid systems that are currently in use. Development efforts on hybrids revealed two important problem areas: (1) low frequency instabilities and (2) slow transient response. Both of these are closely related to the transient behavior which is a poorly understood aspect of hybrid operation. This thesis is mainly involved with a theoretical study of transient combustion in hybrid rockets. We follow the methodology of identifying and modeling the subsystems of the motor such as the thermal lags in the solid, boundary layer combustion and chamber gasdynamics from a dynamic point of view. We begin with the thermal lag in the solid which yield the regression rate for any given wall heat flux variation. Interesting phenomena such as overshooting during throttling and the amplification and phase lead regions in the frequency domain are discovered. Later we develop a quasi-steady transient hybrid combustion model supported with time delays for the boundary layer processes. This is integrated with the thermal lag system to obtain the thermal combustion (TC) coupled response. The TC coupled system with positive delays generated low frequency instabilities. The scaling of the instabilities are in good agreement with actual motor test data. Finally, we formulate a gasdynamic model for the hybrid chamber which successfully resolves the filling/emptying and longitudinal acoustic behavior of the motor. The TC coupled system is later integrated to the gasdynamic model to obtain the overall response (TCG coupled system) of gaseous oxidizer motors with stiff feed systems. Low frequency instabilities were also encountered for the TCG coupled system. Apart from the transient investigations, the regression rate behavior of liquefying hybrid propellants such as solid cryogenic materials are also studied. The theory is based on the possibility of enhancement of regression rate by the entrainment mass transfer from a liquid layer formed on the fuel surface. The predicted regression rates are in good agreement with the cryogenic experimental findings obtained recently at Edwards Airforce Base with a frozen pentane and gaseous oxygen system.

Karabeyoglu, Mustafa Arif

1998-09-01

361

The Neuromediator Glutamate, through Specific Substrate Interactions, Enhances Mitochondrial ATP Production and Reactive Oxygen Species Generation in Nonsynaptic Brain Mitochondria*  

PubMed Central

The finding that upon neuronal activation glutamate is transported postsynaptically from synaptic clefts and increased lactate availability for neurons suggest that brain mitochondria (BM) utilize a mixture of substrates, namely pyruvate, glutamate, and the tricarboxylic acid cycle metabolites. We studied how glutamate affected oxidative phosphorylation and reactive oxygen species (ROS) production in rat BM oxidizing pyruvate + malate or succinate. Simultaneous oxidation of glutamate + pyruvate + malate increased state 3 and uncoupled respiration by 52 and 71%, respectively. The state 4 ROS generation increased 100% over BM oxidizing pyruvate + malate and 900% over that of BM oxidizing glutamate + malate. Up to 70% of ROS generation was associated with reverse electron transport. These effects of pyruvate + glutamate + malate were observed only with BM and not with liver or heart mitochondria. The effects of glutamate + pyruvate on succinate-supported respiration and ROS generation were not organ-specific and depended only on whether mitochondria were isolated with or without bovine serum albumin. With the non-bovine serum albumin brain and heart mitochondria oxidizing succinate, the addition of pyruvate and glutamate abrogated inhibition of Complex II by oxaloacetate. We conclude that (i) during neuronal activation, simultaneous oxidation of glutamate + pyruvate temporarily enhances neuronal mitochondrial ATP production, and (ii) intrinsic inhibition of Complex II by oxaloacetate is an inherent mechanism that protects against ROS generation during reverse electron transport.

Panov, Alexander; Schonfeld, Peter; Dikalov, Sergey; Hemendinger, Richelle; Bonkovsky, Herbert L.; Brooks, Benjamin Rix

2009-01-01

362

Silica-coated gold nanostars for combined surface-enhanced Raman scattering (SERS) detection and singlet-oxygen generation: a potential nanoplatform for theranostics.  

PubMed

This paper reports the synthesis and characterization of surface-enhanced Raman scattering (SERS) label-tagged gold nanostars, coated with a silica shell containing methylene blue photosensitizing drug for singlet-oxygen generation. To our knowledge, this is the first report of nanocomposites possessing a combined capability for SERS detection and singlet-oxygen generation for photodynamic therapy. The gold nanostars were tuned for maximal absorption in the near-infrared (NIR) spectral region and tagged with a NIR dye for surface-enhanced resonance Raman scattering (SERRS). Silica coating was used to encapsulate the photosensitizer methylene blue in a shell around the nanoparticles. Upon 785 nm excitation, SERS from the Raman dye is observed, while excitation at 633 nm shows fluorescence from methylene blue. Methylene-blue-encapsulated nanoparticles show a significant increase in singlet-oxygen generation as compared to nanoparticles synthesized without methylene blue. This increased singlet-oxygen generation shows a cytotoxic effect on BT549 breast cancer cells upon laser irradiation. The combination of SERS detection (diagnostic) and singlet-oxygen generation (therapeutic) into a single platform provides a potential theranostic agent. PMID:21859159

Fales, Andrew M; Yuan, Hsiangkuo; Vo-Dinh, Tuan

2011-09-02

363

Numerical Simulation on Forced Swirl Combustion Chamber in Diesel Engine  

Microsoft Academic Search

A concept of forced swirl combustion chamber in diesel engine is proposed in this paper. It can be used to enhance the intensity of swirl flow in the cylinder and accelerate the rate of air-fuel mixture process by designing the special structure in the combustion chamber. This new type of forced swirl combustion chamber includes double swirl combustion chamber that

Shang Yong; Liu Fu-shui; Li Xiang-rong

2011-01-01

364

Numerical Simulation on Forced Swirl Combustion Chamber in Diesel Engine  

Microsoft Academic Search

A concept of forced swirl combustion chamber in diesel engine is proposed in this paper. It can be used to enhance the intensity of swirl flow in the cylinder and accelerate the rate of air-fuel mixture process by designing the special structure in the combustion chamber. This new type of forced swirl combustion chamber includes double swirl combustion chamber that

Shang Yong; Liu Fu-shui; Li Xiang-rong

2010-01-01

365

FORMATION AND CONTROL OF PRODUCTS OF INCOMPLETE COMBUSTION  

EPA Science Inventory

Oxygenated organic products of incomplete combustion, including oxygenated PAHs and phthalates, have been found in combustor emissions. Some have substantial health effects and significantly influence the risk assessment calculations. Others are found that may or may not be a...

366

Enhancement of the antitumor effect of glucose oxidase by combined administration of hydrogen peroxide decomposition inhibitors together with an oxygenated fluorocarbon.  

PubMed

Glucose oxidase (GO) catalyzes the conversion of beta-D-glucose and molecular oxygen to D-glucono-delta-lactone and H2O2. H2O2 produced by GO was effective in preventing tumor growth in mice bearing not only ascites tumor but also solid tumor. The effect of GO was enhanced by the combined administration of catalase inhibitors such as 3-aminotriazole, hydroxylamine and sodium azide or the GSH synthesis inhibitor buthionine-(S,R)-sulfoximine in vivo. The cytolytic activity of GO against T-24 cultured cells in vitro was also enhanced by addition of these inhibitors together with GO. In the peritoneal cavity of mice the antitumor effect of GO seemed to be dependent on the amount of oxygen released from oxygenated fluorocarbon-43 (FC-O2), an oxygen-supplying substance. Furthermore, the combined administration of H2O2-decomposing enzyme inhibitors and FC-O2 synergistically enhanced the antitumor effect of GO. These results suggest that GO is suitable for antitumor chemotherapy and that the use of inhibitors of H2O2-decomposing enzymes and FC-O2 potentiated the GO therapy. PMID:1910030

Higuchi, Y; Shoin, S; Matsukawa, S

1991-08-01

367

Formation consolidation using a combustible liner  

Microsoft Academic Search

In a method of consolidating an incompetent formation, a liner of combustible material is positioned in a well at a point contiguous to the formation and then ignited to heat the formation to a temperature sufficient to consolidate it. A gas containing oxygen is supplied to the liner during combustion and is preferably supplied at a pressure sufficient to establish

Vogt; T. C. Jr

1968-01-01

368

Prooxidant Action of Maltol: Role of Transition Metals in the Generation of Reactive Oxygen Species and Enhanced Formation of 8-hydroxy-2?-deoxyguanosine Formation in DNA  

Microsoft Academic Search

Maltol (3-hydroxy-2-methyl-4-pyrone) produced reactive oxygen species as a complex with transition metals. Maltol\\/iron complex\\u000a inactivated aconitase the most sensitive enzyme to oxidative stress. The inactivation of aconitase was iron-dependent, and\\u000a prevented by TEMPOL, a scavenger of reactive oxygen species, suggesting that the maltol\\/iron-mediated generation of superoxide\\u000a anion is responsible for the inactivation of aconitase. Addition of maltol effectively enhanced the

Keiko Murakami; Kumiko Ishida; Kyoko Watakabe; Ryoko Tsubouchi; Miyako Haneda; Masataka Yoshino

2006-01-01

369

Hydrogen Generation During In-Situ Combustion  

Microsoft Academic Search

BP Resources Canada Ltd. is operating an oxygen in-situ oil recovery pilot at Marguerite Lake, part of the Cold Lake heavy-oil deposit in eastern Alberta. The pilot consists of two principal areas: a three-well, wet air combustion test and an infill-drilled, four five-spot, wet oxygen combustion project on 2 hectare spacing (5 acres). All the wells were initially steam fractured

L. E. Hajdo; R. J. Hallam; L. D. L. Vorndran

1985-01-01

370

Developmental programming of eNOS uncoupling and enhanced vascular oxidative stress in adult rats after transient neonatal oxygen exposure.  

PubMed

The authors have previously shown that neonatal hyperoxic stress leads to high blood pressure, impaired endothelium-mediated vasodilatation, and increased vascular production of superoxide anion by NAD(P)H oxidase in adulthood. However, it is unknown whether changes in nitric oxide (NO) production and/or bioinactivation prevail and whether NO synthase (NOS) is also a source of superoxide. The purpose of this study was to evaluate whether adult animals exposed to neonatal hyperoxic stress have impaired vascular NO production associated with NOS uncoupling participating to vascular superoxide production and vascular dysfunction. In adult male rats exposed to 80% oxygen from day 3 to 10 of life (H, n = 6) versus room air controls (CTRL, n = 6), vascular (aorta) NO production is decreased at baseline (CTRL: 21 ± 1 vs. H: 16 ± 2 4,5-diaminofluorescein diacetate fluorescence intensity arbitrary units; P < 0.05) and after carbachol stimulation (acetylcholine analog; CTRL: 26 ± 2 vs. H: 18±2; P < 0.05). Pretreatment with L-arginine (CTRL: 32 ± 4 vs. H: 31 ± 5) and L-sepiapterine [analog of key NOS cofactor tetrahydro-L-biopterin (BH4)] (CTRL: 30 ± 3 vs. H: 29 ± 3) normalizes NO production after carbachol. L-Sepiapterine also normalizes impaired vasodilatation to carbachol. Vascular endothelial NO synthase (eNOS) immunostaining is reduced, whereas total eNOS protein expression is increased in H (CTRL: 0.76 ± 0.08 vs. H: 1.76± 0.21; P < 0.01). The significantly higher superoxide generation (CTRL: 20 ± 2 vs. H: 28 ± 3 hydroethidine fluorescence intensity arbitrary units; P < 0.05) is prevented by pretreatment with the eNOS inhibitor N-nitro-L-arginine methyl ester (CTRL: 21 ± 4 vs. H: 22 ± 4). Taken together, the current data indicate a role for eNOS uncoupling in enhanced vascular superoxide, impaired endothelium-mediated vasodilatation, and decreased NO production in adult animals with programmed elevated blood pressure after a brief neonatal oxygen exposure. PMID:23011469

Yzydorczyk, Catherine; Comte, Blandine; Huyard, Fanny; Cloutier, Anik; Germain, Nathalie; Bertagnolli, Mariane; Nuyt, Anne Monique

2013-01-01

371

Oxygen-cutting of Vanadium  

Microsoft Academic Search

THE mechanism controlling the oxygen-cutting of iron and steel has been investigated by this Association, primarily along the lines of previous work by Wells1, whereby attention was focused on the iron\\/oxygen combustion process. Recently this work has been extended to the study of the general conditions governing the progress of flame cuts through elementary materials, propagated by combustion with a

G. Coates

1958-01-01

372

Technology evaluation report: SITE (Superfund Innovative Technology Evaluation) program demonstration test. The American Combustion Pyretron Thermal Destruction System at the US EPA's (Environmental Protection Agency's) combustion research facility  

SciTech Connect

A series of demonstration tests of the American Combustion, Inc., Thermal Destruction System was performed under the SITE program. This oxygen-enhanced combustion system was retrofit to the rotary-kiln incinerator at EPA's Combustion Research Facility. The system's performance was tested firing contaminated soil from the Stringfellow Superfund Site, both alone and mixed with a coal tar waste (KO87). Comparative performance with conventional incinerator operation was also tested. Compliance with the incinerator performance standards of 99.99% principal organic hazardous constituents (POHC) destruction and removal efficiency and particulate emissions of less than 180 mg/dscm at 7% O2 was measured for all tests. The Pyretron system was capable of in-compliance performance at double the mixed waste feedrate and at a 60% increase in batch waste charge mass than possible with conventional incineration. Scrubber blowdown and kiln ash contained no detectable levels of any of the POHCs chosen.

Waterland, L.; Lee, J.W.

1989-04-01

373

Experimental investigation of NO x emissions in oxycoal combustion  

Microsoft Academic Search

This work presents the results of an experimental investigation on NOx emissions from coal combustion in a pilot scale test facility. Three oxidiser atmospheres have been compared, namely air, CO2\\/O2, and O2 enriched recirculated flue gas. NOx emissions from two different combustion modes have been studied, swirl flame and flameless combustion. The influence of the burner oxygen ratio and the

Hannes Stadler; Dominik Christ; Martin Habermehl; Peter Heil; Arno Kellermann; Andreas Ohliger; Dobrin Toporov; Reinhold Kneer

2011-01-01

374

Real-time quantitative analysis of combustion-generated polycyclic aromatic hydrocarbons by resonance-enhanced multiphoton ionization time-of-flight mass spectrometry  

SciTech Connect

We have combined resonance-enhanced multiphoton ionization (REMPI) time-of-flight mass spectrometry with on-line flame sampling to determine the centerline concentrations of naphthalene, fluorene, and anthracene in a pure methane + oxygen/argon (1:5) diffusion flame. Naphthalene concentrations between 100 parts per billion by volume (ppbV) and 6 parts per million by volume (ppmV) and fluorene concentrations below 50 ppbV are determined using one-color REMPI on jet-cooled samples extracted from the flame; anthracene concentrations in the 5-40 ppbV range are determined using two-color REMPI. The REMPI ion signals are converted to absolute concentrations in real time by performing gas-phase standard additions to the flame sample. Isomer-selective detection of larger polycyclic aromatic hydrocarbons, such as perylene and benzo[a]pyrene, is possible using the two-color REMPI approach. 38 refs., 8 figs.

Gittins, C.M.; Rohlfing, E.A. [Sandia National Lab., Livermore, CA (United States); Castaldi, M.J.; Senkan, S.M. [Univ. of California, Los Angeles, CA (United States)

1997-02-01

375

Aluminum-doped ceria-zirconia solid solutions with enhanced thermal stability and high oxygen storage capacity.  

PubMed

A facile solvothermal method to synthesize aluminum-doped ceria-zirconia (Ce0.5Zr0.5-xAlxO2-x/2, x?=?0.1 to 0.4) solid solutions was carried out using Ce(NH4)2(NO3)6, Zr(NO3)3·2H2O Al(NO3)3·9H2O, and NH4OH as the starting materials at 200°C for 24 h. The obtained solid solutions from the solvothermal reaction were calcined at 1,000°C for 20 h in air atmosphere to evaluate the thermal stability. The synthesized Ce0.5Zr0.3Al0.2O1.9 particle was characterized for the oxygen storage capacity (OSC) in automotive catalysis. For the characterization, X-ray diffraction, transmission electron microscopy, and the Brunauer-Emmet-Teller (BET) technique were employed. The OSC values of all samples were measured at 600°C using thermogravimetric-differential thermal analysis. Ce0.5Zr0.3Al0.2O1.9 solid solutions calcined at 1,000°C for 20 h with a BET surface area of 18 m2 g-1 exhibited a considerably high OSC of 427 ?mol-O g-1 and good OSC performance stability. The same synthesis route was employed for the preparation of the CeO2 and Ce0.5Zr0.5O2. The incorporation of aluminum ion in the lattice of ceria-based catalyst greatly enhanced the thermal stability and OSC. PMID:23025588

Dong, Qiang; Yin, Shu; Guo, Chongshen; Sato, Tsugio

2012-10-01

376

Oxygen free radicals enhance the nitric oxide-induced covalent NAD(+)-linkage to neuronal glyceraldehyde-3-phosphate dehydrogenase.  

PubMed

Nitric oxide (NO) induces a covalent modification of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from various tissues. This phenomenon, which has previously been interpreted as an auto-ADP-ribosylation, is in fact a covalent binding of NAD+ to the enzyme. In the present study, we show that 3-morpholino-sydnonimine (SIN-1) is much more efficient than sodium nitroprusside (SNP) in stimulating the covalent labelling of GAPDH from cultured striatal neurones in the presence of [adenylate-32P]NAD+ (877 +/- 110 and 266 +/- 33% increase in NAD(+)-labelling induced by maximally effective concentrations of SIN-1 and SNP respectively). The difference in the efficacy of both NO-generating compounds could be due to the additional release of superoxide by SIN-1, since superoxide dismutase and the nitrone 5,5'-dimethyl pyrroline-1-oxide markedly inhibited the SIN-1-induced covalent binding of NAD+ to GAPDH. Catalase and selective scavengers of hydroxyl radicals, mannitol and dimethyl sulphoxide, did not alter the SIN-1-induced covalent modification of GAPDH, ruling out the involvement of hydroxyl radicals in this phenomenon. Supporting further a role of oxygen free radicals in the NAD+ linkage to GAPDH, pyrogallol, a superoxide generator, which alone was ineffective, potentiated the SNP-evoked response. The NAD+ linkage to neuronal GAPDH measured in the presence of NO and superoxide probably involves sulphydryl groups, since the radiolabelling of the protein was reversed by exposure to HgCl2 and prevented by pretreatment with the alkylating agent N-ethylmaleimide. Moreover, the NO-induced inhibition of GAPDH activity was enhanced by pyrogallol, which was ineffective alone. In conclusion, the present study indicates that superoxide anions potentiate NO-induced covalent NAD(+)-linkage to GAPDH and enzyme inactivation. PMID:7639707

Marin, P; Maus, M; Bockaert, J; Glowinski, J; Prémont, J

1995-08-01

377

Assessment of the effect of high ash content in pulverized coal combustion  

SciTech Connect

The existing literature on CFD-based coal combustion modelling is applicable mainly for coals of low ash content and the calculations are done on an ash-free basis. In Indian coals, the ash content may be significantly higher, up to 40% or more. Studies reported in the literature show that the mineral matter in the coal may have a number of effects on the combustion characteristics. In the present study, a sensitivity analysis is performed, using the CFD code CFX of AEA Technology, on the likely effect of ash content on the char reactivity, oxygen diffusion rate for char combustion and on the radiative heat transfer parameters. The results show that the effect of enhanced char reactivity is negligible whereas reduced oxygen diffusion rates due to a thicker ash layer may result in a significant reduction in char oxidation rates with a resultant decrease in the peak temperature in the furnace. The global parameters such as the peak temperature and the flue gas temperature remain relatively insensitive to the presence of high ash content. These results are consistent with the experimental observations of Kurose et al. . Kurose, M. Ikeda, H. Makino, Combustion characteristics of high ash coal in pulverized coal combustion, J. Fuel 80 (2001) 1447-1455).

Jayanti, S.; Maheswaran, K.; Saravanan, V. [Indian Institute of Technology, Madras (India). Dept. of Chemical Engineering

2007-05-15

378

Combustion systems  

SciTech Connect

This patent describes an external combustion engine such as a Stirling engine and the like, having an external heat system housing in which is defined a heater space, a hollow liner formed of a ceramic material disposed in the heater space and defining a combustion chamber. Biasing means are coupled to a first end of the liner and coupled with the housing so as to maintain the liner in the heater space while dampening transmission of vibration in the housing to the liner.

Kralick, J.

1986-03-04

379

The Characteristics of Direct Hydroxylation of Benzene to Phenol with Molecular Oxygen Enhanced by Pulse DC Corona at Atmospheric Pressure  

Microsoft Academic Search

The direct hydroxylation of benzene using molecular oxygen by atmospheric pulse DC corona discharge was investigated. The conversion of benzene increased with the increase of oxygen content and input voltage but the selectivity of phenol decreased due to the formation of polymerized products. The reactivity was also influenced by the kind and content of background inert gas. By using argon

Dae-Won Lee; Jung-Hyun Lee; Bae-Hyeock Chun; Kwan-Young Lee

2003-01-01

380

Investigation of gasification chemical looping combustion combined cycle performance  

Microsoft Academic Search

A novel combined cycle based on coal gasification and chemical looping combustion (CLC) offers a possibility of both high net power efficiency and separation of the greenhouse gas CO. The technique involves the use of a metal oxide as an oxygen carrier, which transfers oxygen from the combustion air to the fuel, and the avoidance of direct contact between fuel

Wenguo Xiang; Sha Wang; Tengteng Di

2008-01-01

381

Color stability and biochemical characteristics of bovine muscles when enhanced with L- or D-potassium lactate in high-oxygen modified atmospheres  

Microsoft Academic Search

Two different bovine muscles –M.longissimus lumborum (LD) and M. psoas major (PM) – were injection-enhanced (n=10, respectively) with solutions containing phosphate and potassium L- or D-lactate, cut into steaks, packaged with a high-oxygen (80% O2) modified atmosphere packaging, stored 9d at 2°C and then displayed for 5d at 1°C. Instrumental color, total reducing activity (TRA), lactate dehydrogenase (LDH) activity, and

Y. H. Kim; J. T. Keeton; H. S. Yang; S. B. Smith; J. E. Sawyer; J. W. Savell

2009-01-01

382

Pt-Decorated PdCo@Pd\\/C Core-Shell Nanoparticles with Enhanced Stability and Electrocatalytic Activity for Oxygen Reduction Reaction  

Microsoft Academic Search

A simple method for the preparation of PdCo@Pd core-shell nanoparticles supported on carbon has been developed using an adsorbate-induced surface segregation effect. The stability and electrocatalytic activity for the oxygen reduction of PdCo@Pd nanoparticles was enhanced by a small amount of Pt, deposited via a spontaneous displacement reaction. The facile method described herein is suitable for large-scale lower cost production

Deli Wang; Huolin L. Xin; Yingchao Yu; Hongsen Wang; Eric Rus; David A. Muller; Hector D. Abruña

2010-01-01

383

Oxygen-assisted enhancement of H atom UV-photogeneration from hydrocarbons in van der Waals complexes RH-O2  

NASA Astrophysics Data System (ADS)

The strong enhancement of H-atom UV-photogeneration is revealed in van der Waals complexes of unsaturated hydrocarbons RH (RHethylene C2H4, propylene C3H6, butadiene C4H6, butene-2 C4H8) with oxygen RH-O2 as compared with the 'free' RH molecules. The results obtained indicate enhancement of H atom yield to be due to one-quantum photoprocess 1RH-3O2 + h? ? 3RH? + 3O2(1O2) providing triplet RH molecules with excitation level sufficient for dissociation.

Baklanov, Alexey V.; Bogomolov, Alexandr S.; Chikishev, Leonid M.; Bogdanchikov, Georgii A.; Kochubei, Sergei A.

2013-02-01

384

Collect Oxygen Over Water  

NSDL National Science Digital Library

In this activity, learners use a pneumatic trough (see related activity) to generate and collect pure oxygen. Learners will test to see if they've generated oxygen by observing the combustion of elemental sulfur, which yields a brilliant blue flame of sulfur oxidation. The manganese dioxide catalyst used in this process is easily recovered from a spent zinc-carbon battery (see related activity).

Ragan, Sean M.

2011-01-01

385

Chemical-looping combustion using syngas as fuel  

Microsoft Academic Search

Chemical-looping combustion (CLC) is a combustion technology where an oxygen carrier is used to transfer oxygen from the combustion air to the fuel, avoiding direct contact between air and fuel. Thus, CO2 and H2O are inherently separated from the rest of the flue gases and the carbon dioxide can be obtained in a pure form without the use of an

Tobias Mattisson; Francisco García-Labiano; Bernhard Kronberger; Anders Lyngfelt; Juan Adánez; Hermann Hofbauer

2007-01-01

386

Low flame temperature limits for mixing-controlled Diesel combustion  

Microsoft Academic Search

The low flame temperature limits for mixing-controlled Diesel combustion were investigated in a constant-volume combustion chamber at well-defined ambient conditions. Flame temperatures were controlled by varying ambient oxygen concentration or by using fuel-lean mixing-controlled combustion. Pressure rise measurements show that combustion efficiency remains high for flame temperatures as low as 1500–1600K for conditions where the ambient gas temperature was greater

Lyle M. Pickett

2005-01-01

387

Enhanced growth and recombinant protein production of Escherichia coli by a perfluorinated oxygen carrier in miniaturized fed-batch cultures  

PubMed Central

Background Liquid perfluorochemicals (PFCs) are interesting oxygen carriers in medicine and biotechnology with a high solubility for oxygen. They have been repeatedly used for improving oxygen transfer into prokaryotic and eukaryotic cell cultures, however their application is still limited. Here we show the great benefit of air/oxygen saturated perfluorodecalin (PFD) for high cell density cultivation of Escherichia coli in microwell plates and their positive effect on the soluble production of a correctly folded heterologously expressed alcohol dehydrogenase. Results In EnBase® cultivations the best effect was seen with PFD saturated with oxygen enriched air (appr. 10 ?M oxygen per ml) when PFD was added at the time of induction. In contrast the effect of PFD was negligible when it was added already at the time of inoculation. Optimisation of addition time and content of loaded oxygen into the PFD resulted in an increased the cell density by 40% compared to control cultures, and correspondingly also the product yield increased, demonstrated at the example of a recombinant alcohol dehydrogenase. Conclusions PFCs are a valuable additive in miniaturized cell culture formats. For production of recombinant proteins in low cell density shaken cultures the addition of oxygen-enriched PFD makes the process more robust, i.e. a high product yield is not any more limited to a very narrow cell density window during which the induction has to be done. The positive effect of PFD was even more obvious when it was added during high cell density cultures. The effect of the PFD phase depends on the amount of oxygen which is loaded into the PFD and which thus is a matter of optimisation.

2011-01-01

388

Effective Heat of Combustion for Flaming Combustion of Mediterranean Forest Fuels  

Microsoft Academic Search

An adapted bench-scale Mass Loss Calorimeter (MLC) device is proposed for evaluating effective heat of rapid flaming combustion\\u000a of fine Mediterranean forest fuels. The MLC apparatus uses a calibrated thermopile to quantify heat release rate (HRR) as\\u000a an alternative to the classical oxygen consumption measurement. A porous holder was used to simulate rapid flaming combustion.\\u000a Average effective heat of combustion

J. Madrigal; M. Guijarro; C. Hernando; C. Díez; E. Marino

2011-01-01

389

PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES: Laser-Induced Particle Jet and Its Ignition Application in Premixed Combustible Gases  

NASA Astrophysics Data System (ADS)

A hot particle jet is induced as a laser pulse from a free oscillated Nd:YAG laser focused on a coal target. The particle jet successfully initiates combustion in a premixed combustible gas consisting of hydrogen, oxygen, and air. The experiment reveals that the ionization of the particle jet is enhanced during the laser pulse. This characteristic is attributed to the electron cascade process and the ionization of the particles or molecules of the target. The initial free electrons, which are ablated from the coal target, are accelerated by the laser pulse through the inverse Bremsstrahlung process and then collide with the neutrals in the jet, causing the latter to be ionized.

Yang, Qian-Suo; Liu, Chun; Peng, Zhi-Min; Zhu, Nai-Yi

2009-06-01

390

Study of the Current Group Evaporation/Combustion Theories.  

National Technical Information Service (NTIS)

Liquid fuel combustion can be greatly enhanced by disintegrating the liquid fuel into droplets, an effect achieved by various configurations. A number of experiments carried out in the seventies showed that combustion of droplet arrays and sprays do not f...

H. H. Shen

1990-01-01

391

Comparison of Different Global Reaction Mechanisms for MILD Combustion of Natural Gas  

Microsoft Academic Search

Emissions of nitrogen oxides from fossil fuel combustion are a major environmental problem because they have been shown to contribute to the formation of acid rain and photochemical smog. MILD (Moderate and Intensive Low oxygen Dilution) combustion is a promising technology to decrease pollutant emissions and to improve combustion efficiency. A combination of air preheating and fuel dilution with combustion

Ju Pyo Kim; Uwe Schnell; Günter Scheffknecht

2008-01-01

392

Low NOx Combustion of DME by Means of Flue Gas Recirculation  

Microsoft Academic Search

This study focuses on the fundamental characteristics of DME (Dimethyl Ether) combustion aiming at development of low-NOx combustion technology with flue gas recirculation, FGR. The flue gas is recirculated into the combustion chamber to reduce the oxygen concentration and to suppress the combustion gas temperature, so that NOx emission is significantly reduced. The fuel gas recirculation at high mixing ratio,

Ryosuke Matsumoto; Mamoru Ozawa; Shinya Terada; Takenori Iio

2008-01-01

393

Influence of temperature, pH and dissolved oxygen concentration on enhanced biological phosphorus removal under strictly aerobic conditions.  

PubMed

Previous research has suggested that enhanced biological phosphorus removal (EBPR) from wastewater can be achieved under continuous aerobic conditions over the short term. However, little is known how environmental conditions might affect aerobic EBPR performance. Consequently we have investigated the impact of temperature, pH and dissolved oxygen (DO) concentrations on EBPR performance under strictly aerobic conditions. A sequencing batch reactor (SBR) was operated for 108 days on a six-hour cycle (four cycles a day). The SBR ran under alternating anaerobic-aerobic conditions as standard and then operated under strictly aerobic conditions for one cycle every three or four days. SBR operational temperature (10, 15, 20, 25 and 30°C), pH (6, 7, 8 and 9) and DO concentration (0.5, 2.0 and 3.5mg/L) were changed consecutively during the aerobic cycle. Recorded increases in mixed liquor phosphorus (P) concentrations during aerobic carbon source uptake (P release) were affected by the biomass P content rather than the imposed changes in the operational conditions. Thus, P release levels increased with biomass P content. By contrast, subsequent aerobic P assimilation (P uptake) levels were both affected by changes in operational temperature and pH, and peaked at 20-25°C and pH 7-8. Highest P uptake detected under these SBR operating conditions was 15.4 mg Pg-MLSS(-1) (at 25°C, pH 7 and DO 2.0mg/L). The ability of the community for linked aerobic P release and P uptake required the presence of acetate in the medium, a finding which differs from previous data, where these are reported to occur in the absence of any exogenous carbon source. Fluorescence in situ hybridization was performed on samples collected from the SBR, and Candidatus 'Accumulibacter phosphatis' cells were detected with PAOmix probes through the operational periods. Thus, Candidatus 'Accumulibacter phosphatis' seemed to perform P removal in the SBR as shown in previous studies on P removal under strictly aerobic conditions. PMID:21718809

Nittami, Tadashi; Oi, Hiroshi; Matsumoto, Kanji; Seviour, Robert J

2011-06-28

394

Formation of Hydrogen Peroxide and Reduction of Peroxynitrite via Dismutation of Superoxide at Reperfusion Enhances Myocardial Blood Flow and Oxygen Consumption in Postischemic Mouse Heart  

PubMed Central

Reactive oxygen/nitrogen species suppress myocardial oxygen consumption. In this study, we determined that endogenous hydrogen peroxide through dismutation of superoxide enhances postischemic myocardial blood perfusion and oxygen consumption. Electron paramagnetic resonance oximetry was applied to monitor in vivo tissue Po2 in mouse heart subjected to regional ischemia reperfusion. Heart rate, arterial blood pressure, blood flow, infarction, and activities of mitochondrial NADH dehydrogenase and cytochrome c oxidase were measured in six groups of wild-type (WT) and endothelial nitric-oxide synthase knock-out (eNOS?/?) mice treated with phosphate-buffered saline (PBS), superoxide dismutase mimetic (SODm) M40403 [a manganese(II)-bis(cyclohexylpyridine)-substituted macrocyclic superoxide dismutase mimetic, C21H35Cl2MnN5], 10006329 EUK 134 [EUK134, manganese 3-methoxy N,N1-bis(salicyclidene)ethylenediamine chloride], and SODm plus glibenclamide to study the protective effect of hydrogen peroxide via dismutation of superoxide on the activation of sarcolemmal potassium channels. In the PBS group, there was an overshoot of tissue Po2 after reperfusion. Treatment with SODm, EUK134, and SODm + glibenclamide protected mitochondrial enzyme activities, reduced infarct size, and suppressed the post-ischemic hyperoxygenation. In particular, in the SODm-treated group, there was a transient peak of tissue Po2 at 9 min after reperfusion, which was dependent on endogenous hydrogen peroxide but not nitric oxide formation as it appeared in both WT and eNOS?/? mice. Blood flow and rate pressure product were higher in the SODm group than in other groups, which contributed to the transient oxygen peak. Thus, SOD mimetics protected mouse heart from superoxide-induced reperfusion injury. With treatment of different SOD mimetics, it is concluded that endogenous hydrogen peroxide via dismutation of superoxide at reperfusion enhances postischemic myocardial blood perfusion and mitochondrial oxygen consumption, possibly through activation of sarcolemmal ATP-sensitive potassium channels.

Xu, Yi; Liu, Bin; Zweier, Jay L.; He, Guanglong

2008-01-01

395

Biofuels combustion.  

PubMed

This review describes major features of current research in renewable fuels derived from plants and from fatty acids. Recent and ongoing fundamental studies of biofuel molecular structure, oxidation reactions, and biofuel chemical properties are reviewed, in addition to combustion applications of biofuels in the major types of engines in which biofuels are used. Biofuels and their combustion are compared with combustion features of conventional petroleum-based fuels. Two main classes of biofuels are described, those consisting of small, primarily alcohol, fuels (particularly ethanol, n-butanol, and iso-pentanol) that are used primarily to replace or supplement gasoline and those derived from fatty acids and used primarily to replace or supplement conventional diesel fuels. Research efforts on so-called second- and third-generation biofuels are discussed briefly. PMID:23298249

Westbrook, Charles K

2013-01-04

396

Catalytic combustion of chlorobenzene over Mn-Ce-La-O mixed oxide catalysts.  

PubMed

A series of Mn(x)-CeLa mixed oxide catalysts with different compositions prepared by sol-gel method were tested for the catalytic combustion of chlorobenzene (CB), as a model of chlorinated aromatics. Mn(x)-CeLa catalysts with the ratios of Mn/(Mn + Ce + La) in the range from 0.69 to 0.8 were found to possess high catalytic activity in the catalytic combustion of CB. The stability and deactivation of Mn(x)-CeLa catalysts were studied by other assistant experiments. Mn(x)-CeLa catalysts can deactivate below 330 °C, due to the strong adsorption of Cl species produced during the decomposition of CB. Nevertheless, the increase in oxygen concentration can enhance the resistance to Cl poisoning through the reaction of surface oxygen species with residual chlorine. At 350 °C, high activity, good selectivity and desired stability were observed over Mn(x)-CeLa catalysts. PMID:21320750

Yu, Dai; Xingyi, Wang; Dao, Li; Qiguang, Dai

2011-01-26

397

Laser diagnostics of plasma assisted combustion  

NASA Astrophysics Data System (ADS)

In this study, a microwave re-entrant cavity discharge system and a direct current (DC) plasmatron are used to investigate flame enhancement and nitric oxide (NO) formation using laser and optical diagnostics. The uniqueness of this study lies in the direct coupling concept, a novel highly efficient strategy used here for the first time. To investigate combustion dynamics of direct microwave coupled combustion, an atmospheric high-Q re-entrant cavity applicator is used to couple microwave (2.45 GHz) electromagnetic energy directly into the reaction zone of a premixed laminar methane-oxygen flame using a compact torch. When microwave energy increases, a transition from electric field enhancement to microwave plasma discharge is observed. At 6 to 10 Watts, ionization and eventually break-down occurs. 2-D laser induced fluorescence (LIF) imaging of hydroxyl radicals (OH) and carbon monoxide (CO) is conducted in the reaction zone over this transition, as well as spectrally resolved flame emission measurements. These measurements serve to monitor excited state species and derive rotational temperatures using OH chemiluminescence for a range of equivalence ratios (both rich and lean) and total flow rates. Combustion dynamics is also investigated for plasma enhanced methane-air flames in premixed and nonpremixed configurations using a transient arc DC plasmatron. Results for OH and CO PLIF also indicate the differences in stability mechanism, and energy consumption for premixed and nonpremixed modes. It is shown that both configurations are significantly influenced by in-situ fuel reforming at higher plasma powers. Parametric studies are conducted in a plasma assisted methane/air premixed flame for quantitative NO production using a DC plasmatron with PLIF imaging. Quantitative measurements of NO are reported as a function of gas flow rate (20 to 50 SCFH), plasma power (100 to 900 mA, 150 to 750 W) and equivalence ratio (0.7 to 1.3). NO PLIF images and single point NO concentrations are presented for both plasma discharge only and for methane/air plasma enhanced combustion cases. NO formation occurs predominantly through N2(v)+O?NO+N for the pure plasma discharge without combustion. The NO concentration for the plasma enhanced combustion case (500 to 3500 ppm) was an order of magnitude smaller than the pure plasma discharge (8000 to 15000 ppm) due to the reduction of nitrogen break up from plasma reactions by the methane. Experiments show the linear decay of NO between the equivalence ratio range 0.8 to 1.2 under the same flow condition and discharge current. The diagnostic methods performed in this study include: (1) species concentration by laser induced fluorescence (NO, OH and CO); (2) rotational temperature by optical emission spectroscopy; (3) excited species emission by optical emission spectroscopy; (4) IR thermometry; and (5) multi-line NO PLIF thermometry.

Rao, Xing

398

Prooxidant action of maltol: role of transition metals in the generation of reactive oxygen species and enhanced formation of 8-hydroxy-2'-deoxyguanosine formation in DNA.  

PubMed

Maltol (3-hydroxy-2-methyl-4-pyrone) produced reactive oxygen species as a complex with transition metals. Maltol/iron complex inactivated aconitase the most sensitive enzyme to oxidative stress. The inactivation of aconitase was iron-dependent, and prevented by TEMPOL, a scavenger of reactive oxygen species, suggesting that the maltol/iron-mediated generation of superoxide anion is responsible for the inactivation of aconitase. Addition of maltol effectively enhanced the ascorbate/copper-mediated formation of 8-hydroxy-2'-deoxyguanosine in DNA. Oxidation of ascorbic acid by CuSO(4) was effectively stimulated by addition of maltol, and the enhanced oxidation rate was markedly inhibited by the addition of catalase and superoxide dismutase. These results suggest that maltol can stimulate the copper reduction coupled with the oxidation of ascorbate, resulting in the production of superoxide radical which in turn converts to hydrogen peroxide and hydroxyl radical. Cytotoxic effect of maltol can be explained by its prooxidant properties: maltol/transition metal complex generates reactive oxygen species causing the inactivation of aconitase and the production of hydroxyl radical causing the formation of DNA base adduct. PMID:16799863

Murakami, Keiko; Ishida, Kumiko; Watakabe, Kyoko; Tsubouchi, Ryoko; Haneda, Miyako; Yoshino, Masataka

2006-06-01

399

Stratified combustion type engine  

Microsoft Academic Search

The present invention relates to a stratified combustion type engine comprising an engine cylinder, a main combustion chamber located above the cylinder, an injection nozzle for injecting auxiliary fuel towards the combustion chamber, and an open pre-combustion chamber provided within the combustion chamber for locally holding and vaporizing the flow of auxiliary fuel from the injection nozzle. The pre-combustion chamber

Kamiya

1977-01-01

400

Stratified combustion type engine  

Microsoft Academic Search

A stratified combustion type engine is described that is comprised of an engine cylinder, a main combustion chamber located above the cylinder, an injection nozzle for injecting auxiliary fuel towards the combustion chamber, and an open pre-combustion chamber provided within the combustion chamber for locally holding and vaporizing the flow of auxiliary fuel from the injection nozzle. The pre-combustion chamber

Kamiya

1978-01-01

401

Nano-structured manganese oxide as a cathodic catalyst for enhanced oxygen reduction in a microbial fuel cell fed with a synthetic wastewater.  

PubMed

Microbial fuel cells (MFCs) provide new opportunities for the simultaneous wastewater treatment and electricity generation. Enhanced oxygen reduction capacity of cost-effective metal-based catalysts in an air cathode is essential for the scale-up and commercialization of MFCs in the field of wastewater treatment. We demonstrated that a nano-structured MnO(x) material, prepared by an electrochemically deposition method, could be an effective catalyst for oxygen reduction in an MFC to generate electricity with the maximum power density of 772.8 mW/m(3) and remove organics when the MFC was fed with an acetate-laden synthetic wastewater. The nano-structured MnO(x) with the controllable size and morphology could be readily obtained with the electrochemical deposition method. Both morphology and manganese oxidation state of the nano-scale catalyst were largely dependent on the electrochemical preparation process, and they governed its catalytic activity and the cathodic oxygen reduction performance of the MFC accordingly. Furthermore, cyclic voltammetry (CV) performed on each nano-structured material suggests that the MnO(x) nanorods had an electrochemical activity towards oxygen reduction reaction via a four-electron pathway in a neutral pH solution. This work provides useful information on the facile preparation of cost-effective cathodic catalysts in a controllable way for the single-chamber air-cathode MFC for wastewater treatment. PMID:20638701

Liu, Xian-Wei; Sun, Xue-Fei; Huang, Yu-Xi; Sheng, Guo-Ping; Zhou, Kang; Zeng, Raymond J; Dong, Fang; Wang, Shu-Guang; Xu, An-Wu; Tong, Zhong-Hua; Yu, Han-Qing

2010-07-17

402

Low Oxygen Enhances Primitive and Definitive Neural Stem Cell Colony Formation by Inhibiting Distinct Cell Death Pathways  

PubMed Central

Neural stem cells (NSCs) can be derived from single mouse embryonic stem cells (ESCs) in the absence of instructive factors. Clonal primitive NSC (pNSC) colonies are formed first, and then give rise to clonal, fibroblast growth factor-dependent definitive neural stem cells (dNSCs). We tested low-oxygen culture as a potential method of alleviating the extensive cell death seen in pNSCs and dNSCs. Culture in low (4%) oxygen promoted survival of pNSCs by inhibiting apoptosis-inducing factor (AIF)-dependent cell death, although pNSCs undergo both AIF- and caspase-mediated cell death in 20% oxygen. In contrast, survival of dNSCs in low oxygen was increased by inhibition of caspase-dependent cell death. In normoxia, AIF is implicated in promoting dNSC survival. Neither survival effect was dependent on the main transcriptional effector of hypoxia, hypoxia-inducible factor 1. Low-oxygen concentrations may be involved in expansion of early NSC populations by inhibiting cell death through different pathways in these sequential pNSC and dNSC populations. Stem Cells 2009;27:1879–1886

Clarke, Laura; van der Kooy, Derek

2009-01-01

403

Combustion energy of fullerene soot  

SciTech Connect

The standard energy of combustion of fullerene soot generated in arc discharge was determined to be [minus]36.0 [+-] 0.5 kJ g[sup [minus]1] by oxygen-bomb combustion calorimetry. The value was much closer to those of C[sub 60] and C[sub 70] than that of graphite. This result provides an energetic reason for the remarkable yield of fullerenes in arc discharge and supports the mechanism of fullerene formation, where fullerenes are the lowest energy products. Fullerene onion formation is interpreted in terms of energy relaxation of the fullerene soot. 20 refs., 1 tab.

Man, Naoki; Nagano, Yatsuhisa; Kiyobayashi, Tetsu; Sakiyama, Minoru (Osaka Univ., Toyonaka (Japan))

1995-02-23

404

Understanding Piloted Ignition of Solid Combustibles in Spacecraft Environments through Numerical Modeling  

NASA Astrophysics Data System (ADS)

Space exploration vehicles can present internal atmospheres different from sea level standard atmospheric conditions (100 kPa, 21%O2). In NASA's most recent human space exploration crew vehicles the cabin environments were designed to have reduced ambient pressure and increased oxygen concentration (around 55 kPa, 32%O2,). These distinct ambient conditions, in addition to the absence of gravity, may increase the fire risk of combustible materials on board. Enhancing the oxygen concentration will lead to higher flame temperatures. Reducing the ambient pressure will decrease convective heat losses from heated surfaces but also will reduce the amount of pyrolyzate required to reach a flammable mixture near the pilot. This study explores the effect of ambient variables such as reduced pressure, oxygen concentration or microgravity on the physical mechanisms that lead to the piloted ignition of solid combustibles through numerical analysis. Two-dimensional simulations of piloted ignition of thermally irradiated samples of PMMA (polymethyl- methacrylate) were performed with the Fire Dynamics Simulator (FDS5) code. Finite-rate single-step combustion kinetics is used in the gas-phase and a single step Arrhenius type reaction rate describes the solid pyrolysis. Oxidative pyrolysis is not considered and the in-depth formed pyrolyzate is assumed to flow unrestricted through the PMMA. The model correctly describes the thermo-physical mechanisms leading to the piloted ignition of solid fuels. It is shown that as the ambient pressure is reduced or the oxygen concentration enhanced, both the time to ignition and the fuel mass loss rate at ignition are reduced, increasing the fire hazard of the material when externally heated. The calculated ignition times and mass loss rates at ignition are compared to those measured experimentally in a laboratory-scale combustion wind tunnel. It is also shown that with appropriate kinetic parameters the model agrees qualitatively well with the experimental data.

Fereres, S.; Fernandez-Pello, C.; Ruff, G.; Urban, D.

2012-01-01

405

Exergy analysis of chemical-looping combustion systems  

Microsoft Academic Search

A power plant based on chemical-looping combustion offers both a possibility of high net power efficiency and separation of the greenhouse gas CO2. This is due to the way the oxidation of the fuel takes place. Instead of oxidizing the fuel with oxygen from the combustion air, the fuel is oxidized by an oxygen carrier, i.e., an oxygen-containing compound. The

Marie Anheden; Gunnar Svedberg

1998-01-01

406

Photostability enhancement of Pyrromethene 567 and Perylene Orange in oxygen-free liquid and solid dye lasers  

SciTech Connect

We investigated the effect of oxygen on the photostability of the laser dyes Pyrromethene 567, Perylene Orange, and Rhodamine 590 by determining their longevity of laser operation when pumped by the second harmonic of a Q-switched Nd:YAG laser. In solution, dissolved oxygen accelerated the photodegradation of Pyrromethene 567 and Perylene Orange but not Rhodamine 590. The photostability of Pyrromethene 567 was also found to be dependent on the solvent and on the lifetime of singlet oxygen. Deoxygenated Pyrromethene 567 doped polycom glass and modified poly(methyl methacrylate) (MPMMA) samples were tested for longevity of laser operation. A factor of 6 improvement in photostability was found for Pyrromethene 567 in MPMMA upon deoxygenation, and the total absorbed energy per mole of dye molecules to one-half output pulse energy was 36 GJ mol{sup {minus}1}. {copyright} 1997 Optical Society of America

Rahn, Mark D.; King, Terence A. [Laser Photonics Group, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Hamblett, Ian [Department of Chemistry, University of Manchester, Manchester M13 9PL (United Kingdom)

1997-08-01

407

Enhanced loading of Fura-2/AM calcium indicator dye in adult rodent brain slices via a microfluidic oxygenator.  

PubMed

A microfluidic oxygenator is used to deliver constant oxygen to rodent brain slices, enabling the loading of the cell-permeant calcium indicator Fura-2/AM into cells of adult brain slices. When compared to traditional methods, our microfluidic oxygenator improves loading efficiency, measured by the number of loaded cells per unit area, for all tested age groups. Loading in slices from 1-year-old mice was achieved, which has not been possible with current bulk loading methods. This technique significantly expands the age range for which calcium studies are possible without cellular injection. This technique will facilitate opportunities for the study of calcium signaling of aging and long term stress related diseases. Moreover, it should be applicable to other membrane-permeant physiological indicator varieties. PMID:23608309

Mauleon, Gerardo; Lo, Joe F; Peterson, Bethany L; Fall, Christopher P; Eddington, David T

2013-04-19

408

High temperature oxidation of Nb, NbC and Ni{sub 3}Nb and oxygen enhanced crack growth  

SciTech Connect

Previous studies have shown that oxygen increased the rates of crack growth in Ni base superalloys at high temperatures (> 800 K) by up to four orders of magnitude over those observed in an inert environment for alloys such as inconel 718, Rene-95 and x 750. In this study, high temperature oxidation studies of pure Nb, NbC and Ni{sub 3}Nb using XPS were undertaken (a) to provide direct confirmation of the oxidation of NbC, (b) to explore the possible role of Ni{sub 3}Nb and (c) to assess the relative reactivity of the latter two phases, along with Nb, with oxygen. Nb, NbC and Ni{sub 3}Nb were oxidized as a function of temperature and constant oxygen exposure, and the results are presented in this communication.

Miller, C.F.; Simmons, G.W.; Wei, R.P.

2000-01-01

409

Enthalpies of Combustion and Formation of Cyclopropylamine. The C-N Thermochemical Bond Energy.  

National Technical Information Service (NTIS)

The standard enthalpy of combustion of liquid cyclopropylamine was found by oxygen-bomb combustion calorimetry. The enthalpy of vaporization was derived from vapor pressure measurements, and the standard enthalpy of formation in the ideal gaseous state wa...

R. T. Moore W. D. Good

1971-01-01

410

Enhanced ferromagnetic and metal insulator transition in Sm0.55Sr0.45MnO3 thin films: Role of oxygen vacancy induced quenched disorder  

NASA Astrophysics Data System (ADS)

Effect of quenched disorder (QD) caused by oxygen vacancy (OV) and substrate induced inhomogeneous compressive strain, on the magnetic and transport properties of oriented polycrystalline Sm0.55Sr0.45MnO3 thin films is investigated. QD is related intimately to the ordering/disordering of the OVs and controls the paramagnetic-ferromagnetic/insulator-metal transition. OV ordered films show enhanced TC/TIM~165 K, which is depressed by oxygen annealing. OV disordering realized by quenching reduces TC/TIM. The first order IM transition observed in SSMO single crystals is transformed into nonhysteretic and continuous one in the OV ordered films. QD appears to be diluted by OV disorder/annihilation and results in stronger carrier localization.

Srivastava, M. K.; Siwach, P. K.; Kaur, A.; Singh, H. K.

2010-11-01

411

The standard molar enthalpies of formation of 5,10,15,20-tetraphenylporphine and 5,10,15,20-tetrakis(4-methoxyphenyl)porphine by oxygen bomb combustion calorimetry  

Microsoft Academic Search

The standard massic energies of combustion ?cuoatT=298.15K were determined from combustion calorimetry experiments for solid 5,10,15,20-tetraphenylporphine (TPP, Chemical Abstracts registry number 917-23-7) and 5,10,15,20-tetrakis (4-methoxyphenyl) porphine (TMPP, Chemical Abstracts registry number 22112-78-3), leading to the following results: [table] where ?cUmo, ?cHmo, and ?fHmodenote the standard molar energy of combustion, standard molar enthalpy of combustion, and standard molar enthalpy of formation,

R. Patiño; L. A. Torres; M. Campos

1999-01-01

412

High temperature oxidation of Nb, NbC and Ni 3Nb and oxygen enhanced crack growth  

Microsoft Academic Search

Previous studies have shown that oxygen increased the rates of crack growth in Ni base superalloys at high temperatures (> 800 K) by up to four orders of magnitude over those observed in an inert environment for alloys such as inconel 718, Rene-95 and x 750. In this study, high temperature oxidation studies of pure Nb, NbC and NiâNb using

Christopher F Miller; Gary W Simmons; Robert P Wei

2000-01-01

413

Neutrophil killing of human umbilical vein endothelial cells is oxygen radical-mediated and enhanced by TNF. alpha  

Microsoft Academic Search

Human umbilical vein endothelial cells are sensitive to killing by activated human neutrophils. Killing is inhibited in the presence of catalase and deferoxamine mesylate but not soybean trypsin inhibitor. Reagent hydrogen peroxide can substitute for activated neutrophils in producing endothelial cell injury. These data suggest that lethal injury is due to the production of oxygen radicals by activated neutrophils. In

M. K. Dame; J. Varani; J. M. Weinberg; P. A. Ward

1991-01-01

414

Enhanced blue-violet emission by inverse energy transfer to the Ge-related oxygen deficiency centers via Er3+ ions in metal-oxide semiconductor structures  

NASA Astrophysics Data System (ADS)

It is generally believed that the 1.5 ?m Er luminescence is enhanced by transferring energy from Si nanocrystals to the nearest Er3+ ions in Er-doped Si-rich SiO2 layers during optical pumping. Here, the influence of Ge nanocrystals instead of excess Si in the same environment is studied using electroluminescence technique on metal-oxide-semiconductor structures. An increase of the 400 nm electroluminescence intensity with a concomitant reduction of the Er-related emission is observed. This is explained in the light of an inverse energy transfer process from Er3+ to the Ge-related oxygen-deficiency centers.

Kanjilal, A.; Rebohle, L.; Voelskow, M.; Skorupa, W.; Helm, M.

2009-02-01

415

Effect of diluted and preheated oxidizer on the emission of methane flameless combustion  

NASA Astrophysics Data System (ADS)

In combustion process, reduction of emissions often accompanies with output efficiency reduction. It means, by using current combustion technique it is difficult to obtainlow pollution and high level of efficiency in the same time. In new combustion system, low NOxengines and burners are studied particularly. Recently flameless or Moderate and Intensive Low oxygen Dilution (MILD) combustion has received special attention in terms of low harmful emissions and low energy consumption. Behavior of combustion with highly preheated air was analyzed to study the change of combustion regime and the reason for the compatibility of high performance and low NOx production. Sustainability of combustion under low oxygen concentration was examined when; the combustion air temperature was above the self-ignition temperature of the fuel. This paper purposes to analyze the NOx emission quantity in conventional combustion and flameless combustion by Chemical Equilibrium with Applications (CEA) software.

Hosseini, Seyed Ehsan; Salehirad, Saber; Wahid, M. A.; Sies, Mohsin Mohd; Saat, Aminuddin

2012-06-01

416

Pumping oxygen into gasoline  

SciTech Connect

To reduce atmospheric concentration of certain pollutants notably carbon monoxide (CO), incompletely combusted hydrocarbons and nitrogen oxides (NOx), EPA as early as January 1988 began testing oxygenated fuels in such cities as Denver and Albuquerque, N.M. The CAA Amendments require using oxygenated gasoline in cities where CO levels exceed National Ambient Air Quality standards. The law, which became effective Nov. 2, affects about 40 urban areas during the winter, when CO levels are higher. Methyl tertiary butyl ether (MTBE), methanol, ethyl tertiary butyl ether (ETBE) or ethanol are used to increase the oxygen content of motor fuel. Do these additives improve air quality The answer is a qualified no. Although oxygenated fuels reduce emissions from older automobiles, there is no statistical improvement in automotive emissions for newer vehicles equipped with three-way catalytic converters. Oxygenates have increased overall fuel cost $14 million annually in the Denver area but have not improved air quality as expected.

Wray, T.K.

1993-10-01

417

Test Operation of Oxygen-Enriched Incinerator for Wastes From Nuclear Fuel Fabrication Facility  

Microsoft Academic Search

The oxygen-enriched combustion concept, which can minimize off-gas production, has been applied to the incineration of combustible uranium-containing wastes from a nuclear fuel fabrication facility. A simulation for oxygen combustion shows the off-gas production can be reduced by a factor of 6.7 theoretically, compared with conventional air combustion. The laboratory-scale oxygen enriched incineration (OEI) process with a thermal capacity of

J.-G. Kim; H. c C. Yang; G.-I. Park; I.-T. Kim; J.-K. Kim

2002-01-01

418

Proceedings - 3rd joint SPE/DOE symposium on enhanced oil recovery  

SciTech Connect

This conference proceedings contains 53 papers. Topics covered include: carbon dioxide flooding; high solubilization of brine and oil recovery; seismic imaging; monitoring method for carbon dioxide flooding; LPG flood evaluation; tertiary oil recovery; chemical enhancement of oil production; in-situ combustion; measuring steam quality; downhole steam generator; oxygen combustion process for heavy oil recovery; fracture-assisted steam flood; polymers for enhanced oil recovery; sealing of linear and pattern chemical floods; interfacial light scattering in microemulsion; and well injection. All papers are abstracted separately.

Not Available

1982-01-01

419

Enhancing Effect of the Endocrine Disruptor para-Nonylphenol on the Generation of Reactive Oxygen Species in Human Blood Neutrophils  

Microsoft Academic Search

Although para-nonylphenol (NP) is known as an endocrine disruptor, the immunologic effect of NP has been poorly analyzed. We found that NP from 5 to 50 µM caused a dose-dependent stimu- latory effect on the generation of reactive oxygen species (ROS) in human blood neutrophils, which was measured by using a chemiluminescence reagent, luminol. Furthermore, ROS-scavenging enzymes such as catalase

Yasuji Okai; Eisuke F. Sato; Kiyoka Higashi-Okai; Masayasu Inoue

2004-01-01

420

Emodin Enhances Arsenic Trioxide-Induced Apoptosis via Generation of Reactive Oxygen Species and Inhibition of Survival Signaling  

Microsoft Academic Search

Although arsenic trioxide (As2O3) induces apoptosis in a relatively wide spectrum of tumors, the sensitivity of different cell types to this treatment varies to a great extent. Because reactive oxygen species (ROS) are critically involved in As2O3-induced apoptosis, we attempted to explore the possibility that elevating the cellular ROS level might be an approach to facilitate As2O3-induced apoptosis. Emodin, a

Jing Yi; Jie Yang; Rong He; Fei Gao; Hairong Sang; Xueming Tang; Richard D. Ye

2004-01-01

421

Synergistic Enhancement of the Postthaw Growth of Cryopreserved Rice Cells by Oxygenated Perfluorocarbon and Pluronic F-68  

Microsoft Academic Search

The beneficial effects were assessed of supplementing culture medium with oxygenated perfluorocarbon, both alone and in combination with 0.01 (w\\/v) Pluronic F-68, on the postthaw viability, following cryopreservation, of suspension cultured cells of the Japonica rice,Oryza sativacv. Taipei 309. The mean viability, as assessed by triphenyl tetrazolium chloride reduction, of cells at 4 days after thawing was increased 20% over

P. Anthony; K. C. Lowe; J. B. Power; M. R. Davey

1997-01-01

422

Oxygen- and NssR-dependent globin expression and enhanced iron acquisition in the response of campylobacter to nitrosative stress.  

PubMed

Pathogenic bacteria experience nitrosative stress from NO generated in the host and from nitrosating species such as S-nitrosoglutathione. The food-borne pathogen Campylobacter jejuni responds by activating gene expression from a small regulon under the control of the NO-sensitive regulator, NssR. Here, we describe the full extent of the S-nitrosoglutathione response using transcriptomic and proteomic analysis of batch- and chemostat-cultured C. jejuni. In addition to the NssR regulon, which includes two hemoglobins (Cgb and Ctb), we identify more than 90 other up-regulated genes, notably those encoding heat shock proteins and proteins involved in oxidative stress tolerance and iron metabolism/transport. Up-regulation of a subset of these genes, including cgb, is also elicited by NO-releasing compounds. Mutation of the iron-responsive regulator Fur results in insensitivity of growth to NO, suggesting that derepression of iron-regulated genes and augmentation of iron acquisition is a physiological response to nitrosative damage. We describe the effect of oxygen availability on nitrosative stress tolerance; cells cultured at higher rates of oxygen diffusion have elevated levels of hemoglobins, are more resistant to inhibition by NO of both growth and respiration, and consume NO more rapidly. The oxygen response is mediated by NssR. Thus, in addition to NO detoxification catalyzed by the hemoglobins Cgb and possibly Ctb, C. jejuni mounts an extensive stress response. We suggest that inhibition of respiration by NO may increase availability of oxygen for Cgb synthesis and function. PMID:18682395

Monk, Claire E; Pearson, Bruce M; Mulholland, Francis; Smith, Holly K; Poole, Robert K

2008-08-05

423

Intermittent high glucose enhances cell proliferation and VEGF expression in retinal endothelial cells: the role of mitochondrial reactive oxygen species  

Microsoft Academic Search

Proliferation of human retinal endothelial cells (HRECs) is an important event in the development of diabetic retinopathy.\\u000a Glucose fluctuations are strong predictor of diabetic vascular complications. In this study we have investigated the effect\\u000a of intermittent high glucose on proliferation and expression of vascular endothelial growth factor (VEGF) in HRECs. The possible\\u000a involvement of mitochondrial reactive oxygen species (ROS) was

Jiazhong SunYancheng XuSuxin Sun; Yancheng Xu; Suxin Sun; Yanlei Sun; Xiang Wang

2010-01-01

424

Formation of a long-lived electron-transfer state in mesoporous silica-alumina composites enhances photocatalytic oxygenation reactivity.  

PubMed

A simple donor-acceptor linked dyad, 9-mesityl-10-methylacridinium ion (Acr(+)-Mes) was incorporated into nanosized mesoporous silica-alumina to form a composite, which in acetonitrile is highly dispersed. In this medium, upon visible light irradiation, the formation of an extremely long-lived electron-transfer state (Acr(•)-Mes(•+)) was confirmed by EPR and laser flash photolysis spectroscopic methods. The composite of Acr(+)-Mes-incorporated mesoporous silica-alumina with an added copper complex [(tmpa)Cu(II)] (ClO(4)(-))2 (tmpa = tris(2-pyridylmethyl)amine) acts as an efficient and robust photocatalyst for the selective oxygenation of p-xylene by molecular oxygen to produce p-tolualdehyde and hydrogen peroxide. Thus, incorporation of Acr(+)-Mes into nanosized mesoporous silica-alumina combined with an O(2)-reduction catalyst ([(tmpa)Cu(II)](2+)) provides a promising method in the development of efficient and robust organic photocatalysts for substrate oxygenation by dioxygen, the ultimate environmentally benign oxidant. PMID:22543164

Fukuzumi, Shunichi; Doi, Kaoru; Itoh, Akinori; Suenobu, Tomoyoshi; Ohkubo, Kei; Yamada, Yusuke; Karlin, Kenneth D

2012-04-27

425

Formation of a long-lived electron-transfer state in mesoporous silica-alumina composites enhances photocatalytic oxygenation reactivity  

PubMed Central

A simple donor-acceptor linked dyad, 9-mesityl-10-methylacridinium ion (Acr+-Mes) was incorporated into nanosized mesoporous silica-alumina to form a composite, which in acetonitrile is highly dispersed. In this medium, upon visible light irradiation, the formation of an extremely long-lived electron-transfer state (Acr•-Mes•+) was confirmed by EPR and laser flash photolysis spectroscopic methods. The composite of Acr+-Mes-incorporated mesoporous silica-alumina with an added copper complex [(tmpa)CuII] (tmpa = tris(2-pyridylmethyl)amine) acts as an efficient and robust photocatalyst for the selective oxygenation of p-xylene by molecular oxygen to produce p-tolualdehyde and hydrogen peroxide. Thus, incorporation of Acr+-Mes into nanosized mesoporous silica-alumina combined with an O2-reduction catalyst ([(tmpa)CuII]2+) provides a promising method in the development of efficient and robust organic photocatalysts for substrate oxygenation by dioxygen, the ultimate environmentally benign oxidant.

Fukuzumi, Shunichi; Doi, Kaoru; Itoh, Akinori; Suenobu, Tomoyoshi; Ohkubo, Kei; Yamada, Yusuke; Karlin, Kenneth D.

2012-01-01

426

Enhanced intersystem crossing rate in polymethine-like molecules: sulfur-containing squaraines versus oxygen-containing analogues.  

PubMed

Two different approaches to increase intersystem crossing rates in polymethine-like molecules are presented: traditional heavy-atom substitution and molecular levels engineering. Linear and nonlinear optical properties of a series of polymethine dyes with Br- and Se-atom substitution, and a series of new squaraine molecules, where one or two oxygen atoms in a squaraine bridge are replaced with sulfur atoms, are investigated. A consequence of the oxygen-to-sulfur substitution in squaraines is the inversion of their lowest-lying ??* and n?* states leading to a significant reduction of singlet-triplet energy difference and opening of an additional intersystem channel of relaxation. Experimental studies show that triplet quantum yields for polymethine dyes with heavy-atom substitutions are small (not more than 10%), while for sulfur-containing squaraines these values reach almost unity. Linear spectroscopic characterization includes absorption, fluorescence, quantum yield, anisotropy, and singlet oxygen generation measurements. Nonlinear characterization, performed by picosecond and femtosecond laser systems (pump-probe and Z-scan measurements), includes measurements of the triplet quantum yields, excited state absorption, two-photon absorption, and singlet and triplet state lifetimes. Experimental results are in agreement with density functional theory calculations allowing determination of the energy positions, spin-orbital coupling, and electronic configurations of the lowest electronic transitions. PMID:23427868

Peceli, Davorin; Hu, Honghua; Fishman, Dmitry A; Webster, Scott; Przhonska, Olga V; Kurdyukov, Vladimir V; Slominsky, Yurii L; Tolmachev, Alexey I; Kachkovski, Alexey D; Gerasov, Andrey O; Masunov, Artëm E; Hagan, David J; Van Stryland, Eric W

2013-03-08

427

HEAT TRANSFER IN A PULSE COMBUSTION WATER HEATER  

Microsoft Academic Search

Pulse combustion devices offer several potential advantages over conventional burners, including enhanced efficiency, reduced size, automatic rejection of exhaust gases and consistency of operation over long time periods. This project was conducted in order to acquire an understanding of the heat transfer characteristics and pressure oscillations occurring in pulse combustion devices.^ A gas-fired pulse combustion water heater was utilized. This

HSIN-CHENG GARY HUANG; H. C. G

1984-01-01

428

Modification of synthetic materials to reduce combustibility  

Microsoft Academic Search

The studies conducted demonstrated the effectiveness of using Phosdiol for reducing the combustibility of PE fibres and the\\u000a small effect of PAN and PA fibre fire barriers. The oxygen index of flameproof fibrous polyester material was 27.5%, which\\u000a allows assigning it to difficultly combustible polymers, and the strength of the fibre increases by 12–15%.

V. I. Besshaposhnikova; T. V. Kulikova; T. G. Nikitina; O. A. Grishina; L. G. Panova

2006-01-01

429

Oxygen-induced enhancement of surface plasmon resonance of silver nanoparticles for silver-coated soda-lime glass  

Microsoft Academic Search

The optical properties of a silver film on soda-lime glass substrate were studied after treatment in different atmospheres at different temperatures. It has been shown that pre-treatment in air (at about 500 °C for 1 h) can induce the enhancement of the surface plasmon resonance (SPR) of silver nanoparticles after subsequent treatment in H2. This enhancement effect decreases with decrease

Jinlian Hu; Weiping Cai; Yue Li; Haibo Zeng

2005-01-01

430

Liquid fuel combustion apparatus  

Microsoft Academic Search

This patent describes a vaporized liquid fuel combustion apparatus of the type including: a cylinder defining a combustion chamber, the cylinder having an inlet end for receipt of combustion air and an outlet end for exhausting gaseous combustion products; an end plate covering the inlet end of the cylinder; a blower, including a rotor and a casing, for supplying combustion

K. Sawada; Y. Kimijima; H. Umehara

1986-01-01

431

Gas turbine combustion  

Microsoft Academic Search

This text focuses on the fundamentals of gas turbine combustion, emphasizing combustor design and performance. The material presented is based on the latest research results. Aerodynamic and heat transfer processes in gas turbine combustors as well as the combustion performance parameters of ignition, combustion efficiency, and stability are described. Some of the topics covered are combustion fundamentals; diffusers; aerodynamics; combustion

1983-01-01

432

Mechanistic studies on the degradation of gasoline oxygenates by advanced oxidation technologies and the reaction of 4-methyl-1,2,4-triazoline-3,5-dione with tetracyclopropylethylene  

Microsoft Academic Search

Gasoline oxygenates (MTBE, methyl tert-butyl ether; DIPE, di-isopropyl ether; ETBE, ethyl tert-butyl ether; TAME, tert-amyl ether) are added to gasoline to boost octane and enhance combustion. The combination of large scale use, high water solubility and only minor biodegradability has now resulted in a significant gasoline oxygenate contamination occurring in surface, ground, and drinking water systems. Combination of hydroxyl radical

Duk Kyung Kim

2003-01-01

433

Research on the Ignition-Chamber GDI Engine Combustion System  

NASA Astrophysics Data System (ADS)

The ignition-chamber GDI engine combustion system and its fuel injection strategy were presented and studied by multi-dimensional fluid dynamic (CFD) code and experiment. The CFD research result shows that the ignition-chamber combustion system and its fuel injection strategy can ensure that there is flammable mixture with appropriate concentration distribution near the spark plug to enhance the ignition reliability. The performance of the GDI engine with the ignition-chamber combustion system was investigated basing on the existing experiment condition. The result shows that the ignition-chamber combustion system has the potential of decreasing emissions and enhancing the combustion speed and stability.

Fu, Lei; Ishima, Tsuneaki; Long, Wu-Qiang; Tian, Jiang-Ping