Testing metals and alloys for use in oxygen systems

NASA Technical Reports Server (NTRS)

Stoltzfus, Joel M.

1986-01-01

When oxygen is present in high concentrations or large quantities, as in oxygen-based life-support systems, the likelihood of combustion and the probable intensity of a conflagration increase, together with the severity of the damage caused. Even stainless steel will burn vigorously when ignited in a 1000-psi oxygen environment. The hazards involved in the use of oxygen increase with system operation at the elevated temperatures typical of propulsion systems. Fires in oxygen systems are generally catastrophic, causing a threat to life in manned vehicles. When mechanical components of a mechanism generate friction heat in the presence of oxygen, many commonly used metal alloys ignite and burn. Attention is presently given to frictional heating, particle impact, and flame propagation tests conducted in oxygen environments.

Oxygen Generation from Carbon Dioxide for Advanced Life Support

NASA Technical Reports Server (NTRS)

Bishop, Sean; Duncan, Keith; Hagelin-Weaver, Helena; Neal, Luke; Sanchez, Jose; Paul, Heather L.; Wachsman, Eric

2007-01-01

The partial electrochemical reduction of carbon dioxide (CO2) using ceramic oxygen generators (COGs) is well known and widely studied. However, complete reduction of metabolically produced CO2 (into carbon and oxygen) has the potential of reducing oxygen storage weight for life support if the oxygen can be recovered. Recently, the University of Florida devel- oped novel ceramic oxygen generators employing a bilayer elec- trolyte of gadolinia-doped ceria and erbia-stabilized bismuth ox- ide (ESB) for NASA's future exploration of Mars. The results showed that oxygen could be reliably produced from CO2 at temperatures as low as 400 C. The strategy discussed here for advanced life support systems employs a catalytic layer com- bined with a COG cell so that CO2 is reduced all the way to solid carbon and oxygen without carbon buildup on the COG cell and subsequent deactivation.

Space Technology Game Changing Development- Next Generation Life Support: Spacecraft Oxygen Recovery (SCOR)

NASA Technical Reports Server (NTRS)

Abney, Morgan; Barta, Daniel

2015-01-01

The Next Generation Life Support Spacecraft Oxygen Recovery (SCOR) project element is dedicated to developing technology that enables oxygen recovery from metabolically produced carbon dioxide in space habitats. The state-of-the-art system on the International Space Station uses Sabatier technology to recover (is) approximately 50% oxygen from carbon dioxide. The remaining oxygen required for crew respiration is supplied from Earth. For long duration manned missions beyond low-Earth orbit, resupply of oxygen becomes economically and logistically prohibitive. To mitigate these challenges, the SCOR project element is targeting development of technology to increase the recovery of oxygen to 75% or more, thereby reducing the total oxygen resupply required for future missions.

Status of the International Space Station Regenerative ECLSS Water Recovery and Oxygen Generation Systems

NASA Technical Reports Server (NTRS)

Bagdigian, Robert M.; Cloud, Dale

2005-01-01

NASA is developing three racks containing regenerative water recovery and oxygen generation systems (WRS and OGS) for deployment on the International Space Station (ISS). The major assemblies included in these racks are the Water Processor Assembly (WPA), Urine Processor Assembly (UPA), Oxygen Generation Assembly (OGA), and the Power Supply Module (PSM) supporting the OGA. The WPA and OGA are provided by Hamilton Sundstrand Space Systems International (HSSSI), Inc., while the UPA and PSM are developed in- house by the Marshall Space Flight Center (MSFC). The assemblies have completed the manufacturing phase and are in various stages of testing and integration into the flight racks. This paper summarizes the status as of April 2005 and describes some of the technical challenges encountered and lessons learned over the past year.

Singlet oxygen generation in gas discharge for oxygen-iodine laser pumping

NASA Astrophysics Data System (ADS)

Lopaev, D. V.; Braginsky, O. V.; Klopovsky, K. S.; Kovalev, A. S.; Mankelevich, Yu. A.; Popov, N. A.; Rakhimov, A. T.; Rakhimova, T. V.; Vasilieva, A. N.

2004-09-01

The possibility of development of effective discharged singlet oxygen (SO) generator (DSOG) for oxygen-iodine laser (OIL) is studied in detail. Researches of kinetics of oxygen atoms and oxygen molecules in the lowest metastable singlet states have been carried out in the different discharges and its afterglow (DC discharges, E-beam controlled discharge and RF discharges) in both CW and pulsed mode in a wide range of conditions (pressures, gas mixtures, energy deposits etc.). The models developed for all the discharges have allowed us to analyze SO generation and loss mechanisms and to find out the key-parameters controlling the highest SO yield. It is shown that in addition to spatial plasma uniformity at low E/N and high specific energy deposit per oxygen molecule, DSOG must be oxygen atom free to avoid fast three-body quenching of SO by atomic oxygen with increasing pressure and thereby to provide pressure scaling (in tens Torrs) for applying to real OIL systems.

One-man electrochemical air revitalization system evaluation

NASA Technical Reports Server (NTRS)

Schbert, F. H.; Marshall, R. D.; Hallick, T. M.; Woods, R. R.

1976-01-01

A program to evaluate the performance of a one man capacity, self contained electrochemical air revitalization system was successfully completed. The technology readiness of this concept was demonstrated by characterizing the performance of this one man system over wide ranges in cabin atmospheric conditions. The electrochemical air revitalization system consists of a water vapor electrolysis module to generate oxygen from water vapor in the cabin air, and an electrochemical depolarized carbon dioxide concentrator module to remove carbon dioxide from the cabin air. A control/monitor instrumentation package that uses the electrochemical depolarized concentrator module power generated to partially offset the water vapor electrolysis module power requirements and various structural fluid routing components are also part of the system. The system was designed to meet the one man metabolic oxygen generation and carbon dioxide removal requirements, thereby controlling cabin partial pressure of oxygen at 22 kN/sq m and cabin pressure of carbon dioxide at 400 N/sq m over a wide range in cabin air relative humidity conditions.

Oxygen Handling and Cooling Options in High Temperature Electrolysis Plants

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

Manohar S. Sohal; J. Stephen Herring

2008-07-01

Idaho National Laboratory is working on a project to generate hydrogen by high temperature electrolysis (HTE). In such an HTE system, safety precautions need to be taken to handle high temperature oxygen at ~830°C. This report is aimed at addressing oxygen handling in a HTE plant.. Though oxygen itself is not flammable, most engineering material, including many gases and liquids, will burn in the presence of oxygen under some favorable physicochemical conditions. At present, an absolute set of rules does not exist that can cover all aspects of oxygen system design, material selection, and operating practices to avoid subtle hazardsmore » related to oxygen. Because most materials, including metals, will burn in an oxygen-enriched environment, hazards are always present when using oxygen. Most materials will ignite in an oxygen-enriched environment at a temperature lower than that in air, and once ignited, combustion rates are greater in the oxygen-enriched environment. Even many metals, if ignited, burn violently in an oxygen-enriched environment. However, these hazards do not preclude the operations and systems involving oxygen. Oxygen can be safely handled and used if all the materials in a system are not flammable in the end-use environment or if ignition sources are identified and controlled. In fact, the incidence of oxygen system fires is reported to be low with a probability of about one in a million. This report is a practical guideline and tutorial for the safe operation and handling of gaseous oxygen in high temperature electrolysis system. The intent is to provide safe, practical guidance that permits the accomplishment of experimental operations at INL, while being restrictive enough to prevent personnel endangerment and to provide reasonable facility protection. Adequate guidelines are provided to govern various aspects of oxygen handling associated with high temperature electrolysis system to generate hydrogen. The intent here is to present acceptable oxygen standards and practices for minimum safety requirements. A summary of operational hazards, along with oxygen safety and emergency procedures, are provided.« less

A Brief Study on Toxic Combustion Products of the Polymers Used in High-Pressure Oxygen Systems

NASA Technical Reports Server (NTRS)

Hshieh, Fu-Yu; Beeson, Harold D.

2005-01-01

One likely cause of polymer ignition in a high-pressure oxygen system is the adiabatic-compression heating of polymers caused by pneumatic impact. Oxidative pyrolysis or combustion of polymers in a high-pressure oxygen system could generate toxic gases. This paper investigates the feasibility of using the NASA pneumatic-impact system to conduct adiabatic-compression combustion tests and determines the toxic combustion products produced from the burning of five selected polymers. Five polymers commonly used in high-pressure oxygen systems, Zytel(Registered TradeMark) 42 (Nylon 6/6), Buna N (nitrile rubber), Witon(Registered TradeMark) A (copolymer of vinylidene fluoride and hexafluoropropylene), Neoflon(Registered TradeMark) (polychlorotrifluoroethylene), and Teflon(Registered TradeMark) (polytetrafluoroethylene), were tested in the NASA pneumatic-impact test system at 17.2-MPa oxygen pressure. The polymers were ignited and burned; combustion products were collected in a stainless-steel sample bottle and analyzed using various methods. The results show that the NASA pneumatic-impact system is an appropriate test system to conduct adiabatic-compression combustion tests and to collect combustion products for further chemical analysis. The composition of the combustion product gas generated from burning the five selected polymers are presented and discussed.

Regeneration of oxygen from carbon dioxide and water.

NASA Technical Reports Server (NTRS)

Weissbart, J.; Smart, W. H.; Wydeven, T.

1972-01-01

In a closed ecological system it is necessary to reclaim most of the oxygen required for breathing from respired carbon dioxide and the remainder from waste water. One of the advanced physicochemical systems being developed for generating oxygen in manned spacecraft is the solid electrolyte-electrolysis system. The solid electrolyte system consists of two basic units, an electrolyzer and a carbon monoxide disproportionator. The electrolyzer can reclaim oxygen from both carbon dioxide and water. Electrolyzer preparation and assembly are discussed together with questions of reactor design and electrolyzer performance data.

[Russian oxygen generation system "Elektron-VM": hydrogen content in electrolytically produced oxygen for breathing by International Space Station crews].

PubMed

Proshkin, V Yu; Kurmazenko, E A

2014-01-01

The article presents the particulars of hydrogen content in electrolysis oxygen produced aboard the ISS Russian segment by oxygen generator "Elektron-VM" (SGK) for crew breathing. Hydrogen content was estimated as in the course of SGK operation in the ISS RS, so during the ground life tests. According to the investigation of hydrogen sources, the primary path of H2 appearance in oxygen is its diffusion through the porous diaphragm separating the electrolytic-cell cathode and anode chambers. Effectiveness of hydrogen oxidation in the SGK reheating unit was evaluated.

New singlet oxygen generator for chemical oxygen-iodine lasers

NASA Astrophysics Data System (ADS)

Yoshida, S.; Saito, H.; Fujioka, T.; Yamakoshi, H.; Uchiyama, T.

1986-11-01

Experiments have been carried out to investigate a new method for generating O2(1Delta) with long-time operation of an efficient chemical oxygen-iodine laser system in mind. An impinging-jet nozzle was utilized to atomize a H2O2-KOH solution so that the alkaline H2O2/Cl2 reaction might occur in droplet-gas phase with high excitation efficiency. Experimental results indicate that the present generator can yield as high as 80 percent of O2(1Delta) with reasonable O2 flow rate.

Onboard Inert Gas Generation System/Onboard Oxygen Gas Generation System (OBIGGS/OBOGS) Study. Part 2; Gas Separation Technology--State of the Art

NASA Technical Reports Server (NTRS)

Reynolds, Thomas L.; Eklund, Thor I.; Haack, Gregory A.

2001-01-01

This purpose of this contract study task was to investigate the State of the Art in Gas Separation Technologies utilized for separating air into both nitrogen and oxygen gases for potential applications on commercial aircraft. The intended applications included: nitrogen gas for fuel tank inerting, cargo compartment fire protection, and emergency oxygen for passenger and crew use in the event of loss of cabin pressure. The approach was to investigate three principle methods of gas separation: Hollow Fiber Membrane (HFM), Ceramic Membrane (CM), and liquefaction: Total Atmospheric Liquefaction of Oxygen and Nitrogen (TALON). Additional data on the performance of molecular sieve pressure swing adsorption (PSA) systems was also collected and discussed. Performance comparisons of these technologies are contained in the body of the report.

Formation and Detoxification of Reactive Oxygen Species

ERIC Educational Resources Information Center

Kuciel, Radoslawa; Mazurkiewicz, Aleksandra

2004-01-01

A model of reactive oxygen species metabolism is proposed as a laboratory exercise for students. The superoxide ion in this model is generated during the reaction of oxidation of xanthine, catalyzed by xanthine oxidase. The effect of catalase, superoxide dismutase, and allopurinol on superoxide ion generation and removal in this system is also…

International Space Station (ISS)

NASA Image and Video Library

2000-09-01

The Environmental Control and Life Support System (ECLSS) Group of the Flight Projects Directorate at the Marshall Space Flight Center (MSFC) in Huntsville, Alabama, is responsible for designing and building the life support systems that will provide the crew of the International Space Station (ISS) a comfortable environment in which to live and work. This is a close-up view of ECLSS Oxygen Generation System (OGS) rack. The ECLSS Group at the MSFC oversees the development of the OGS, which produces oxygen for breathing air for the crew and laboratory animals, as well as for replacing oxygen lost due to experiment use, airlock depressurization, module leakage, and carbon dioxide venting. The OGS consists primarily of the Oxygen Generator Assembly (OGA), provided by the prime contractor, the Hamilton Sundstrand Space Systems, International (HSSSI) in Windsor Locks, Cornecticut and a Power Supply Module (PSM), supplied by the MSFC. The OGA is comprised of a cell stack that electrolyzes (breaks apart the hydrogen and oxygen molecules) some of the clean water provided by the Water Recovery System and the separators that remove the gases from water after electrolysis. The PSM provides the high power to the OGA needed to electrolyze the water.

Flight Hydrogen Sensor for use in the ISS Oxygen Generation Assembly

NASA Technical Reports Server (NTRS)

MSadoques, George, Jr.; Makel, Darby B.

2005-01-01

This paper provides a description of the hydrogen sensor Orbital Replacement Unit (ORU) used on the Oxygen Generation Assembly (OGA), to be operated on the International Space Station (ISS). The hydrogen sensor ORU is being provided by Makel Engineering, Inc. (MEI) to monitor the oxygen outlet for the presence of hydrogen. The hydrogen sensor ORU is a triple redundant design where each sensor converts raw measurements to actual hydrogen partial pressure that is reported to the OGA system controller. The signal outputs are utilized for system shutdown in the event that the hydrogen concentration in the oxygen outlet line exceeds the specified shutdown limit. Improvements have been made to the Micro-Electro-Mechanical Systems (MEMS) based sensing element, screening, and calibration process to meet OGA operating requirements. Two flight hydrogen sensor ORUs have successfully completed the acceptance test phase. This paper also describes the sensor s performance during acceptance testing, additional tests planned to extend the operational performance calibration cycle, and integration with the OGA system.

A dual-plate ITO-ITO generator-collector microtrench sensor: surface activation, spatial separation and suppression of irreversible oxygen and ascorbate interference.

PubMed

Hasnat, Mohammad A; Gross, Andrew J; Dale, Sara E C; Barnes, Edward O; Compton, Richard G; Marken, Frank

2014-02-07

Generator-collector electrode systems are based on two independent working electrodes with overlapping diffusion fields where chemically reversible redox processes (oxidation and reduction) are coupled to give amplified current signals. A generator-collector trench electrode system prepared from two tin-doped indium oxide (ITO) electrodes placed vis-à-vis with a 22 μm inter-electrode gap is employed here as a sensor in aqueous media. The reversible 2-electron anthraquinone-2-sulfonate redox system is demonstrated to give well-defined collector responses even in the presence of oxygen due to the irreversible nature of the oxygen reduction. For the oxidation of dopamine on ITO, novel "Piranha-activation" effects are observed and chemically reversible generator-collector feedback conditions are achieved at pH 7, by selecting a more negative collector potential, again eliminating possible oxygen interference. Finally, dopamine oxidation in the presence of ascorbate is demonstrated with the irreversible oxidation of ascorbate at the "mouth" of the trench electrode and chemically reversible oxidation of dopamine in the trench "interior". This spatial separation of chemically reversible and irreversible processes within and outside the trench is discussed as a potential in situ microscale sensing and separation tool.

Solid polymer electrolyte water electrolysis system development. [to generate oxygen for manned space station applications

NASA Technical Reports Server (NTRS)

1975-01-01

Solid polymer electrolyte technology used in a water electrolysis system (WES) to generate oxygen and hydrogen for manned space station applications was investigated. A four-man rated, low pressure breadboard water electrolysis system with the necessary instrumentation and controls was fabricated and tested. A six man rated, high pressure, high temperature, advanced preprototype WES was developed. This configuration included the design and development of an advanced water electrolysis module, capable of operation at 400 psig and 200 F, and a dynamic phase separator/pump in place of a passive phase separator design. Evaluation of this system demonstrated the goal of safe, unattended automated operation at high pressure and high temperature with an accumulated gas generation time of over 1000 hours.

An ultrasonically powered implantable micro-oxygen generator (IMOG).

PubMed

Maleki, Teimour; Cao, Ning; Song, Seung Hyun; Kao, Chinghai; Ko, Song-Chu Arthur; Ziaie, Babak

2011-11-01

In this paper, we present an ultrasonically powered implantable micro-oxygen generator (IMOG) that is capable of in situ tumor oxygenation through water electrolysis. Such active mode of oxygen generation is not affected by increased interstitial pressure or abnormal blood vessels that typically limit the systemic delivery of oxygen to hypoxic regions of solid tumors. Wireless ultrasonic powering (2.15 MHz) was employed to increase the penetration depth and eliminate the directional sensitivity associated with magnetic methods. In addition, ultrasonic powering allowed for further reduction in the total size of the implant by eliminating the need for a large area inductor. IMOG has an overall dimension of 1.2 mm × 1.3 mm × 8 mm, small enough to be implanted using a hypodermic needle or a trocar. In vitro and ex vivo experiments showed that IMOG is capable of generating more than 150 μA which, in turn, can create 0.525 μL/min of oxygen through electrolytic disassociation. In vivo experiments in a well-known hypoxic pancreatic tumor models (1 cm (3) in size) also verified adequate in situ tumor oxygenation in less than 10 min.

Padalka performs maintenance on the BZh-5 Fluid Unit for the Elektron Oxygen Generator during Expedition 9

NASA Image and Video Library

2004-09-08

ISS009-E-21791 (8 September 2004) --- Cosmonaut Gennady I. Padalka, Expedition 9 commander representing Russia's Federal Space Agency, performs maintenance on a spare version of a part connected to the Russian Elektron oxygen generation system in the Zvezda Service Module of the International Space Station (ISS).

Development of advanced generator of singlet oxygen for a COIL

NASA Astrophysics Data System (ADS)

Kodymová, Jarmila; Špalek, Otomar; Jirásek, Vít; Čenský, Miroslav; Hrubý, Jan

2006-05-01

The generator of singlet oxygen (SOG) remains still a challenge for a chemical oxygen-iodine laser (COIL). Hitherto, only chemical generators based on the gas-liquid reaction system (chlorine-basic hydrogen peroxide) can supply singlet oxygen, O II(1Δ), in enough high yields and at pressures to maintain operation of the high power supersonic COIL facilities. Employing conventional generators of jet-type or rotating disc-type makes often problems resulting mainly from liquid droplets entrained by an O II (1Δ) stream into the laser cavity, and a limited scalability of these generators. Advanced generator concepts investigated currently are based on two different approaches: (i)O II(1Δ) generation by the electrical discharge in various configurations, eliminating thus a liquid chemistry, and (ii) O II(1Δ) generation by the conventional chemistry in novel configurations offering the SOG efficiency increase and eliminating drawbacks of existing devices. One of the advanced concepts of chemical generator - a spray SOG with centrifugal separation of gasliquid phases - has been proposed and investigated in our laboratory. In this paper we present a description of the generator principle, some essential results of theoretical estimations, and interim experimental results obtained with the spray SOG.

International Space Station (ISS) Gas Logistics Planning in the Post Shuttle Era

NASA Technical Reports Server (NTRS)

Leonard, Daniel J.; Cook, Anthony J.; Lehman, Daniel A.

2011-01-01

Over its life the International Space Station (ISS) has received gas (nitrogen, oxygen, and air) from various sources. Nitrogen and oxygen are used in the cabin to maintain total pressure and oxygen partial pressures within the cabin. Plumbed nitrogen is also required to support on-board experiments and medical equipment. Additionally, plumbed oxygen is required to support medical equipment as well as emergency masks and most importantly EVA support. Gas are supplied to ISS with various methods and vehicles. Vehicles like the Progress and ATV deliver nitrogen (both as a pure gas and as air) and oxygen via direct releases into the cabin. An additional source of nitrogen and oxygen is via tanks on the ISS Airlock. The Airlock nitrogen and oxygen tanks can deliver to various users via pressurized systems that run throughout the ISS except for the Russian segment. Metabolic oxygen is mainly supplied via cabin release from the Elektron and Oxygen Generator Assembly (OGA), which are water electrolyzers. As a backup system, oxygen candles (Solid Fuel Oxygen Generators-SFOGs) supply oxygen to the cabin as well. In the past, a major source of nitrogen and oxygen has come from the Shuttle via both direct delivery to the cabin as well as to recharge the ISS Airlock tanks. To replace the Shuttle capability to recharge the ISS Airlock tanks, a new system was developed called Nitrogen/Oxygen Recharge System (NORS). NIORS consists of high pressure (7000 psi) tanks which recharge the ISS Airlock tanks via a blowdown fill for both nitrogen and oxygen. NORS tanks can be brought up on most logistics vehicles such as the HTV, COTS, and ATV. A proper balance must be maintained to insure sufficient gas resources are available on-orbit so that all users have the required gases via the proper delivery method (cabin and/or plumbed).

Oxygen discharge and post-discharge kinetics experiments and modeling for the electric oxygen-iodine laser system.

PubMed

Palla, A D; Zimmerman, J W; Woodard, B S; Carroll, D L; Verdeyen, J T; Lim, T C; Solomon, W C

2007-07-26

Laser oscillation at 1315 nm on the I(2P1/2)-->I(2P3/2) transition of atomic iodine has been obtained by a near resonant energy transfer from O2(a1Delta) produced using a low-pressure oxygen/helium/nitric oxide discharge. In the electric discharge oxygen-iodine laser (ElectricOIL) the discharge production of atomic oxygen, ozone, and other excited species adds levels of complexity to the singlet oxygen generator (SOG) kinetics which are not encountered in a classic purely chemical O2(a1Delta) generation system. The advanced model BLAZE-IV has been introduced to study the energy-transfer laser system dynamics and kinetics. Levels of singlet oxygen, oxygen atoms, and ozone are measured experimentally and compared with calculations. The new BLAZE-IV model is in reasonable agreement with O3, O atom, and gas temperature measurements but is under-predicting the increase in O2(a1Delta) concentration resulting from the presence of NO in the discharge and under-predicting the O2(b1Sigma) concentrations. A key conclusion is that the removal of oxygen atoms by NOX species leads to a significant increase in O2(a1Delta) concentrations downstream of the discharge in part via a recycling process; however, there are still some important processes related to the NOX discharge kinetics that are missing from the present modeling. Further, the removal of oxygen atoms dramatically inhibits the production of ozone in the downstream kinetics.

Investigation into the High Voltage Shutdown of the Oxygen Generator System in the International Space Station

NASA Technical Reports Server (NTRS)

Carpenter, Joyce E.; Gentry, Gregory J.; Diderich, Greg S.; Roy, Robert J.; Golden, John L.; VanKeuren, Steve; Steele, John W.; Rector, Tony J.; Varsik, Jerome D.; Montefusco, Daniel J.;

Hydrogen-oxygen steam generator applications for increasing the efficiency, maneuverability and reliability of power production

NASA Astrophysics Data System (ADS)

Schastlivtsev, A. I.; Borzenko, V. I.

2017-11-01

The comparative feasibility study of the energy storage technologies showed good applicability of hydrogen-oxygen steam generators (HOSG) based energy storage systems with large-scale hydrogen production. The developed scheme solutions for the use of HOSGs for thermal power (TPP) and nuclear power plants (NPP), and the feasibility analysis that have been carried out have shown that their use makes it possible to increase the maneuverability of steam turbines and provide backup power supply in the event of failure of the main steam generating equipment. The main design solutions for the integration of hydrogen-oxygen steam generators into the main power equipment of TPPs and NPPs, as well as their optimal operation modes, are considered.

Disk MHD generator study

NASA Technical Reports Server (NTRS)

Retallick, F. D.

1980-01-01

Directly-fired, separately-fired, and oxygen-augmented MHD power plants incorporating a disk geometry for the MHD generator were studied. The base parameters defined for four near-optimum-performance MHD steam power systems of various types are presented. The finally selected systems consisted of (1) two directly fired cases, one at 1920 K (2996F) preheat and the other at 1650 K (2500 F) preheat, (2) a separately-fired case where the air is preheated to the same level as the higher temperature directly-fired cases, and (3) an oxygen augmented case with the same generator inlet temperature of 2839 (4650F) as the high temperature directly-fired and separately-fired cases. Supersonic Mach numbers at the generator inlet, gas inlet swirl, and constant Hall field operation were specified based on disk generator optimization. System pressures were based on optimization of MHD net power. Supercritical reheat stream plants were used in all cases. Open and closed cycle component costs are summarized and compared.

Oxygen Generation System Laptop Bus Controller Flight Software

NASA Technical Reports Server (NTRS)

Rowe, Chad; Panter, Donna

2009-01-01

The Oxygen Generation System Laptop Bus Controller Flight Software was developed to allow the International Space Station (ISS) program to activate specific components of the Oxygen Generation System (OGS) to perform a checkout of key hardware operation in a microgravity environment, as well as to perform preventative maintenance operations of system valves during a long period of what would otherwise be hardware dormancy. The software provides direct connectivity to the OGS Firmware Controller with pre-programmed tasks operated by on-orbit astronauts to exercise OGS valves and motors. The software is used to manipulate the pump, separator, and valves to alleviate the concerns of hardware problems due to long-term inactivity and to allow for operational verification of microgravity-sensitive components early enough so that, if problems are found, they can be addressed before the hardware is required for operation on-orbit. The decision was made to use existing on-orbit IBM ThinkPad A31p laptops and MIL-STD-1553B interface cards as the hardware configuration. The software at the time of this reporting was developed and tested for use under the Windows 2000 Professional operating system to ensure compatibility with the existing on-orbit computer systems.

Hybrid membrane--PSA system for separating oxygen from air

DOEpatents

Staiger, Chad L [Albuquerque, NM; Vaughn, Mark R [Albuquerque, NM; Miller, A Keith [Albuquerque, NM; Cornelius, Christopher J [Blackburg, VA

2011-01-25

A portable, non-cryogenic, oxygen generation system capable of delivering oxygen gas at purities greater than 98% and flow rates of 15 L/min or more is described. The system consists of two major components. The first component is a high efficiency membrane capable of separating argon and a portion of the nitrogen content from air, yielding an oxygen-enriched permeate flow. This is then fed to the second component, a pressure swing adsorption (PSA) unit utilizing a commercially available, but specifically formulated zeolite compound to remove the remainder of the nitrogen from the flow. The system is a unique gas separation system that can operate at ambient temperatures, for producing high purity oxygen for various applications (medical, refining, chemical production, enhanced combustion, fuel cells, etc . . . ) and represents a significant advance compared to current technologies.

Environmental factors and unhealthy lifestyle influence oxidative stress in humans--an overview.

PubMed

Aseervatham, G Smilin Bell; Sivasudha, T; Jeyadevi, R; Arul Ananth, D

2013-07-01

Oxygen is the most essential molecule for life; since it is a strong oxidizing agent, it can aggravate the damage within the cell by a series of oxidative events including the generation of free radicals. Antioxidative agents are the only defense mechanism to neutralize these free radicals. Free radicals are not only generated internally in our body system but also trough external sources like environmental pollution, toxic metals, cigarette smoke, pesticides, etc., which add damage to our body system. Inhaling these toxic chemicals in the environment has become unavoidable in modern civilization. Antioxidants of plant origin with free radical scavenging properties could have great importance as therapeutic agents in several diseases caused by environmental pollution. This review summarizes the generation of reactive oxygen species and damage to cells by exposure to external factors, unhealthy lifestyle, and role of herbal plants in scavenging these reactive oxygen species.

The development and evaluation of a non-pressurised, chemical oxygen reaction generation vessel and breathing system providing emergency oxygen for an extended duration.

PubMed

Dingley, J; Williams, D; Douglas, P; Douglas, M; Douglas, J O

2016-12-01

The objective was to develop a sodium percarbonate/water/catalyst chemical oxygen generator that did not require compressed gas. Existing devices utilising this reaction have a very short duration of action. Preliminary experiments with a glass reaction vessel, water bath and electronic flowmeter indicated that many factors affected oxygen production rate including reagent formulation, temperature, water volume and agitation frequency. Having undertaken full-scale experiments using a stainless steel vessel, an optimum combination of reagents was found to be 1 litre water, 0.75 g manganese dioxide catalyst, 60 g sodium percarbonate granules and 800 g of custom pressed 7.21 (0.28) g sodium percarbonate tablets. This combination of granules and slower dissolution tablets produced a rapid initial oxygen flow to 'purge' an attached low-flow breathing system allowing immediate use, followed by a constant flow meeting metabolic requirements for a minimum of 1 h duration. © 2016 The Association of Anaesthetists of Great Britain and Ireland.

Solar Energy Systems for Lunar Oxygen Generation

NASA Technical Reports Server (NTRS)

Colozza, Anthony J.; Heller, Richard S.; Wong, Wayne A.; Hepp, Aloysius F.

2010-01-01

An evaluation of several solar concentrator-based systems for producing oxygen from lunar regolith was performed. The systems utilize a solar concentrator mirror to provide thermal energy for the oxygen production process. Thermal energy to power a Stirling heat engine and photovoltaics are compared for the production of electricity. The electricity produced is utilized to operate the equipment needed in the oxygen production process. The initial oxygen production method utilized in the analysis is hydrogen reduction of ilmenite. Utilizing this method of oxygen production a baseline system design was produced. This baseline system had an oxygen production rate of 0.6 kg/hr with a concentrator mirror size of 5 m. Variations were performed on the baseline design to show how changes in the system size and process (rate) affected the oxygen production rate. An evaluation of the power requirements for a carbothermal lunar regolith reduction reactor has also been conducted. The reactor had a total power requirement between 8,320 to 9,961 W when producing 1000 kg/year of oxygen. The solar concentrator used to provide the thermal power (over 82 percent of the total energy requirement) would have a diameter of less than 4 m.

Analysis of On-Board Oxygen and Nitrogen Generation Systems for Surface Vessels.

DTIC Science & Technology

1983-06-01

and Pressure Vessel Code SAE AIR 822 Oxygen for General Aviation Aircraft SAE AIR 825 Oxygen for Aircrafts SAE AIR 1059 Transportation and Maintenance...OF THE TITLE MIL-T-27730 Threaded Components MIL-P-27401 A 40 Micron Filter For Nitrogen MIL-V-33650 Internal Straight Threads ASME Code VIII Boiler

Spectrophotometric determination of H2O2-generating oxidases using oxyhemoglobin as oxygen donor and indicator.

PubMed

Bârzu, O; Dânşoreanu, M

1980-01-01

1. Spectrophotometric determination of oxygen uptake using oxyhemoglobin as oxygen donor and indicator was used for assay of H2O2-generating oxidases like monoamine oxidase and glucose oxidase. 2. In order to decompose H2O2 formed during the oxygen uptake, catalase and methanol (or ethanol) was added to the respiratory system. At pH values higher than 7.5 the oxydation of deoxygenated hemoglobin to methemoglobin was less than 3%. 2. Oxidases with low Km for oxygen can be assayed using the spectrophotometric method if suitable correction factors are introduced into the calculation of oxygen uptake. The correction factor represents the ratio of the rate of formation (or disappearance) of one of the reactants and the rate of oxyhemoglobin deoxygenation, measured under identical experimental conditions.

The electrochemical generation of useful chemical species from lunar materials

NASA Technical Reports Server (NTRS)

Tsai, Kan J.; Kuchynka, Daniel J.; Sammells, Anthony F.

1990-01-01

Electrochemical cells have been fabricated for the simultaneous generation of oxygen and lithium from a Li2O-containing molten salt (Li2O-LiCl-LiF). The cell utilizes an oxygen vacancy conducting solid electrolyte, yttria-stabilized zirconia (YSZ), to effect separation between oxygen evolving and lithium reduction half-cell reactions. The cell, which operates at 700-850 C, possesses rapid electrode kinetics at the lithium-alloy electrode with exchange current density values being greater than 60 mA/sq cm. When used in the electrolytic mode, lithium produced at the negative electrode would be continuously removed from the cell for later use (under lunar conditions) as an easily storable reducing agent for the chemical refining of lunar ores. Because of the high reversibility of this electrochemical system, it has also formed the basis for the lithium-oxygen secondary battery system which possesses the highest theoretical energy density yet investigated.

The electrochemical generation of useful chemical species from lunar materials

NASA Astrophysics Data System (ADS)

Tsai, Kan J.; Kuchynka, Daniel J.; Sammells, Anthony F.

Electrochemical cells have been fabricated for the simultaneous generation of oxygen and lithium from a Li2O-containing molten salt (Li2O-LiCl-LiF). The cell utilizes an oxygen vacancy conducting solid electrolyte, yttria-stabilized zirconia (YSZ), to effect separation between oxygen evolving and lithium reduction half-cell reactions. The cell, which operates at 700-850 C, possesses rapid electrode kinetics at the lithium-alloy electrode with exchange current density values being greater than 60 mA/sq cm. When used in the electrolytic mode, lithium produced at the negative electrode would be continuously removed from the cell for later use (under lunar conditions) as an easily storable reducing agent for the chemical refining of lunar ores. Because of the high reversibility of this electrochemical system, it has also formed the basis for the lithium-oxygen secondary battery system which possesses the highest theoretical energy density yet investigated.

A quantum protective mechanism in photosynthesis

NASA Astrophysics Data System (ADS)

Marais, Adriana; Sinayskiy, Ilya; Petruccione, Francesco; van Grondelle, Rienk

2015-03-01

Since the emergence of oxygenic photosynthesis, living systems have developed protective mechanisms against reactive oxygen species. During charge separation in photosynthetic reaction centres, triplet states can react with molecular oxygen generating destructive singlet oxygen. The triplet product yield in bacteria is observed to be reduced by weak magnetic fields. Reaction centres from plants' photosystem II share many features with bacterial reaction centres, including a high-spin iron whose function has remained obscure. To explain observations that the magnetic field effect is reduced by the iron, we propose that its fast-relaxing spin plays a protective role in photosynthesis by generating an effective magnetic field. We consider a simple model of the system, derive an analytical expression for the effective magnetic field and analyse the resulting triplet yield reduction. The protective mechanism is robust for realistic parameter ranges, constituting a clear example of a quantum effect playing a macroscopic role vital for life.

A quantum protective mechanism in photosynthesis.

PubMed

Marais, Adriana; Sinayskiy, Ilya; Petruccione, Francesco; van Grondelle, Rienk

2015-03-03

Since the emergence of oxygenic photosynthesis, living systems have developed protective mechanisms against reactive oxygen species. During charge separation in photosynthetic reaction centres, triplet states can react with molecular oxygen generating destructive singlet oxygen. The triplet product yield in bacteria is observed to be reduced by weak magnetic fields. Reaction centres from plants' photosystem II share many features with bacterial reaction centres, including a high-spin iron whose function has remained obscure. To explain observations that the magnetic field effect is reduced by the iron, we propose that its fast-relaxing spin plays a protective role in photosynthesis by generating an effective magnetic field. We consider a simple model of the system, derive an analytical expression for the effective magnetic field and analyse the resulting triplet yield reduction. The protective mechanism is robust for realistic parameter ranges, constituting a clear example of a quantum effect playing a macroscopic role vital for life.

Testing and Oxygen Assessment Results for a Next Generation Extravehicular Activity Portable Life Support System Fan

NASA Technical Reports Server (NTRS)

Paul, Heather L.; Jennings, Mallory A.; Rivera, Fatonia L.; Martin, Devin

2011-01-01

NASA is designing a next generation Extravehicular Activity (EVA) Portable Life Support System (PLSS) for use in future surface exploration endeavors. To meet the new requirements for ventilation flow at nominal and buddy modes, a fan has been developed and tested. This paper summarizes the results of the performance and life cycle testing efforts conducted at the NASA Johnson Space Center. Additionally, oxygen compatibility assessment results from an evaluation conducted at White Sands Test Facility (WSTF) are provided, and lessons learned and future recommendations are outlined.

14 CFR 25.1450 - Chemical oxygen generators.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Chemical oxygen generators. 25.1450 Section... oxygen generators. (a) For the purpose of this section, a chemical oxygen generator is defined as a device which produces oxygen by chemical reaction. (b) Each chemical oxygen generator must be designed...

14 CFR 25.1450 - Chemical oxygen generators.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Chemical oxygen generators. 25.1450 Section... oxygen generators. (a) For the purpose of this section, a chemical oxygen generator is defined as a device which produces oxygen by chemical reaction. (b) Each chemical oxygen generator must be designed...

14 CFR 25.1450 - Chemical oxygen generators.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Chemical oxygen generators. 25.1450 Section... oxygen generators. (a) For the purpose of this section, a chemical oxygen generator is defined as a device which produces oxygen by chemical reaction. (b) Each chemical oxygen generator must be designed...

Regenerative Aerobraking

NASA Technical Reports Server (NTRS)

Moses, Robert W.

2004-01-01

NASA's exploration goals for Mars and Beyond will require new power systems and in situ resource utilization technologies. Regenerative aerobraking may offer a revolutionary approach for in situ power generation and oxygen harvesting during these exploration missions. In theory, power and oxygen can be collected during aerobraking and stored for later use in orbit or on the planet. This technology would capture energy and oxygen from the plasma field that occurs naturally during hypersonic entry using well understood principles of magnetohydrodynamics and oxygen filtration. This innovative approach generates resources upon arrival at the operational site, and thus greatly differs from the traditional approach of taking everything you need with you from Earth. Fundamental analysis, computational fluid dynamics, and some testing of experimental hardware have established the basic feasibility of generating power during a Mars entry. Oxygen filtration at conditions consistent with spacecraft entry parameters at Mars has been studied to a lesser extent. Other uses of the MHD power are presented. This paper illustrates how some features of regenerative aerobraking may be applied to support human and robotic missions at Mars.

Conceptual design of a lunar oxygen pilot plant Lunar Base Systems Study (LBSS) task 4.2

NASA Technical Reports Server (NTRS)

1988-01-01

The primary objective was to develop conceptual designs of two pilot plants to produce oxygen from lunar materials. A lunar pilot plant will be used to generate engineering data necessary to support an optimum design of a larger scale production plant. Lunar oxygen would be of primary value as spacecraft propellant oxidizer. In addition, lunar oxygen would be useful for servicing nonregenerative fuel cell power systems, providing requirements for life support, and to make up oxygen losses from leakage and airlock cycling. Thirteen different lunar oxygen production methods are described. Hydrogen reduction of ilmenite and extraction of solar-wind hydrogen from bulk lunar soil were selected for conceptual design studies. Trades and sensitivity analyses were performed with these models.

Oxygen-producing inert anodes for SOM process

DOEpatents

Pal, Uday B

2014-02-25

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

Flexible Microsensor Array for the Monitoring and Control of Plant Growth System

NASA Technical Reports Server (NTRS)

Kim, Chang-Soo; Porterfield, D. Marshall; Nagle, H. Troy; Brown, Christopher S.

2004-01-01

Testing for plant experiments in space has begun to explore active nutrient delivery concepts in which water and nutrients are replenished on a continuous basis for long-term growth. The goal of this study is to develop a novel microsensor array to provide information on the dissolved oxygen environment in the plant root zone for the optimum control of hydroponics and solid substrate plant cultivation systems in the space environment. Miniaturized polarographic dissolved oxygen sensors have been designed and fabricated on a flexible Kapton (trademark) (polyimide) substrate. Two capabilities of the new microsensor array were explored. First, measurements of dissolved oxygen in the plant root zone in hydroponics and solid substrate culture systems were made. The microsensor array was fabricated on a flexible substrate, and then cut out into a mesh type to make a suspended array that could be placed either in a hydroponics system or in a solid substrate cultivation system to measure the oxygen environments. Second, the in situ self-diagnostic and self-calibration capability (two-point for oxygen) was adopted by dynamically controlling the microenvironment in close proximity to the microsensors. With a built-in generating electrode that surrounds the microsensor, two kinds of microenvironments (oxygen-saturated and oxygen-depleted phases) could be established by water electrolysis depending on the polarity of the generating electrode. The unique features of the new microsensor array (small size, multiple sensors, flexibility and self-diagnosis) can have exceptional benefits for the study and optimization of plant cultivation systems in both terrestrial and microgravity environments. The in situ self-diagnostic and self-calibration features of the microsensor array will also enable continuous verification of the operability during entire plant growth cycles. This concept of automated control of a novel chemical monitoring system will minimize crew time required for maintenance, as well as reduce volume, mass, and power consumption by eliminating bulky diagnosis systems including calibrant (fluid and gas) reservoir and flow system hardware.

Methods for Incorporating Oxygen-Generating Biomaterials into Cell Culture and Microcapsule Systems.

PubMed

McQuilling, John Patrick; Opara, Emmanuel C

2017-01-01

A major obstacle to long-term performance of tissue construct implants in regenerative medicine is the inherent hypoxia to which cells in the engineered construct are exposed prior to vascularization of the implant. Various approaches are currently being designed to address this problem. An emerging area of interest on this issue is the use of peroxide-based materials to generate oxygen during the critical period of extended hypoxia that occurs from the time cells are in culture waiting to be used in tissue engineering devices through the immediate post-implant period. In this chapter we provide protocols that we have developed for using these chemical oxygen generators in cell culture and tissue constructs as illustrated by pancreatic islet cell microencapsulation.

Improvement of the efficiency of a space oxygen-hydrogen electrochemical generator

NASA Astrophysics Data System (ADS)

Glukhikh, I. N.; Shcherbakov, A. N.; Chelyaev, V. F.

2014-12-01

This paper describes the method used for cooling of an on-board oxygen-hydrogen electrochemical generator (ECG). Apart from electric power, such a unit produces water of reaction and heat; the latter is an additional load on the thermal control system of a space vehicle. This load is undesirable in long-duration space flights, when specific energy characteristics of on-board systems are the determining factors. It is suggested to partially compensate the energy consumption by the thermal control system of a space vehicle required for cooling of the electrochemical generator through evaporation of water of reaction from the generator into a vacuum (or through ice sublimation if the pressure in the ambient space is lower than that in the triple point of water.) Such method of cooling of an electrochemical generator improves specific energy parameters of an on-board electric power supply system, and, due to the presence of the negative feedback, it makes the operation of this system more stable. Estimates suggest that it is possible to compensate approximately one half of heat released from the generator through evaporation of its water of reaction at the electrical efficiency of the electrochemical generator equal to 60%. In this case, even minor increase in the efficiency of the generator would result in a considerable increase in the efficiency of the evaporative system intended for its cooling.

14 CFR 23.1450 - Chemical oxygen generators.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Chemical oxygen generators. 23.1450 Section... Equipment § 23.1450 Chemical oxygen generators. (a) For the purpose of this section, a chemical oxygen generator is defined as a device which produces oxygen by chemical reaction. (b) Each chemical oxygen...

14 CFR 23.1450 - Chemical oxygen generators.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Chemical oxygen generators. 23.1450 Section... Equipment § 23.1450 Chemical oxygen generators. (a) For the purpose of this section, a chemical oxygen generator is defined as a device which produces oxygen by chemical reaction. (b) Each chemical oxygen...

14 CFR 23.1450 - Chemical oxygen generators.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Chemical oxygen generators. 23.1450 Section... Equipment § 23.1450 Chemical oxygen generators. (a) For the purpose of this section, a chemical oxygen generator is defined as a device which produces oxygen by chemical reaction. (b) Each chemical oxygen...

14 CFR 23.1450 - Chemical oxygen generators.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Chemical oxygen generators. 23.1450 Section... Equipment § 23.1450 Chemical oxygen generators. (a) For the purpose of this section, a chemical oxygen generator is defined as a device which produces oxygen by chemical reaction. (b) Each chemical oxygen...

14 CFR 23.1450 - Chemical oxygen generators.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Chemical oxygen generators. 23.1450 Section... Equipment § 23.1450 Chemical oxygen generators. (a) For the purpose of this section, a chemical oxygen generator is defined as a device which produces oxygen by chemical reaction. (b) Each chemical oxygen...

The Roles of Primary Cilia in Cardiovascular System

DTIC Science & Technology

2016-10-01

mitochondrial generation of hydrogen peroxide. General properties and effect of hyperbaric oxygen . Biochem J 134:707–716. Boveris A, Oshino N, Chance B. 1972...The mitochondrial generation of hydrogen peroxide. General properties and effect of hyperbaric oxygen . Biochem J 134:707–716. Boveris A, Oshino N...Aim 1.2 (months 13-30): We will examine signaling mechanisms of cilia & their effects on blood pressure. Aim 2 (months 7-36). We will study

49 CFR 173.168 - Chemical oxygen generators.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 49 Transportation 2 2011-10-01 2011-10-01 false Chemical oxygen generators. 173.168 Section 173... Class 7 § 173.168 Chemical oxygen generators. An oxygen generator, chemical (defined in § 171.8 of this subchapter) may be transported only under the following conditions: (a) Approval. A chemical oxygen generator...

49 CFR 173.168 - Chemical oxygen generators.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 2 2010-10-01 2010-10-01 false Chemical oxygen generators. 173.168 Section 173... Class 7 § 173.168 Chemical oxygen generators. An oxygen generator, chemical (defined in § 171.8 of this subchapter) may be transported only under the following conditions: (a) Approval. A chemical oxygen generator...

49 CFR 173.168 - Chemical oxygen generators.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 49 Transportation 2 2013-10-01 2013-10-01 false Chemical oxygen generators. 173.168 Section 173... Class 7 § 173.168 Chemical oxygen generators. An oxygen generator, chemical (defined in § 171.8 of this subchapter) may be transported only under the following conditions: (a) Approval. A chemical oxygen generator...

49 CFR 173.168 - Chemical oxygen generators.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 49 Transportation 2 2012-10-01 2012-10-01 false Chemical oxygen generators. 173.168 Section 173... Class 7 § 173.168 Chemical oxygen generators. An oxygen generator, chemical (defined in § 171.8 of this subchapter) may be transported only under the following conditions: (a) Approval. A chemical oxygen generator...

49 CFR 173.168 - Chemical oxygen generators.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 49 Transportation 2 2014-10-01 2014-10-01 false Chemical oxygen generators. 173.168 Section 173... Class 7 § 173.168 Chemical oxygen generators. An oxygen generator, chemical (defined in § 171.8 of this subchapter) may be transported only under the following conditions: (a) Approval. A chemical oxygen generator...

Investigation of a sterilization system using active oxygen species generated by ultraviolet irradiation.

PubMed

Yoshino, Kiyoshi; Matsumoto, Hiroyuki; Iwasaki, Tatsuyuki; Kinoshita, Shinobu; Noda, Kazutoshi; Oya, Kei; Iwamori, Satoru

2015-01-01

We have been investigating an advanced sterilization system that employs active oxygen species (AOS). We designed the sterilization equipment, including an evacuation system, which generates AOS from pure oxygen gas using ultraviolet irradiation, in order to study the conditions necessary for sterilization in the system's chamber. Using Geobachillus stearothermophilus spores (10(6) CFU) in a sterile bag as a biological indicator (BI) in the chamber of the AOS sterilization apparatus, we examined the viability of the BI as a function of exposure time, assessing the role of the decompression level in the sterilization performance. We found that the survival curves showed exponential reduction, and that the decompression level did not exert a significant influence on the survival curve. Subsequently, we investigated the sterilization effect as influenced by the spatial and environmental temperature variation throughout the chamber, and found that the sterilization effect varied with position, due to the varying environmental temperature in the respective areas. We confirmed that temperature is one of the most important factors influencing sterilization in the chamber, and estimated the temperature effect on the distribution of atomic oxygen concentration, using the quartz crystal microbalance (QCM) method with fluorocarbon thin film prepared by radio frequency sputtering.

Effects of reactive oxygen species and interplay of antioxidants during physical exercise in skeletal muscles.

PubMed

Thirupathi, Anand; Pinho, Ricardo A

2018-05-01

A large number of researches have led to a substantial growth of knowledge about exercise and oxidative stress. Initial investigations reported that physical exercise generates free radical-mediated damages to cells; however, in recent years, studies have shown that regular exercise can upregulate endogenous antioxidants and reduce oxidative damage. Yet, strenuous exercise perturbs the antioxidant system by increasing the reactive oxygen species (ROS) content. These alterations in the cellular environment seem to occur in an exercise type-dependent manner. The source of ROS generation during exercise is debatable, but now it is well established that both contracting and relaxing skeletal muscles generate reactive oxygen species and reactive nitrogen species. In particular, exercises of higher intensity and longer duration can cause oxidative damage to lipids, proteins, and nucleotides in myocytes. In this review, we summarize the ROS effects and interplay of antioxidants in skeletal muscle during physical exercise. Additionally, we discuss how ROS-mediated signaling influences physical exercise in antioxidant system.

SPE (trademark) Oxygen Generator Assembly (OGA). (Refurbishment of the technology demonstrator LFSPE oxygen generation subsystem)

NASA Technical Reports Server (NTRS)

Roy, Robert J.

1995-01-01

The SPE Oxygen Generator Assembly (OGA) has been modified to correct operational deficiencies present in the original system, and to effect changes to the system hardware and software such that its operating conditions are consistent with the latest configuration requirements for the International Space Station Alpha (ISSA). The effectiveness of these changes has recently been verified through a comprehensive test program which saw the SPE OGA operate for over 740 hours at various test conditions, including over 690 hours, or approximately 460 cycles, simulating the orbit of the space station. This report documents the changes made to the SPE OGA, presents and discusses the test results from the acceptance test program, and provides recommendations for additional development activities pertinent to evolution of the SPE OGA to a flight configuration. Copies of the test data from the acceptance test program are provided with this report on 3.5 inch diskettes in self-extracting archive files.

77 FR 38000 - Airworthiness Directives; Various Transport Category Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-26

... generators in the lavatories until the generator oxygen supply is expended, or removing the oxygen generator(s); and, for each chemical oxygen generator, after the generator is expended (or removed), removing... AD was prompted by reports that the current design of the oxygen generators presents a hazard that...

Relaxation Process of Photoexcited meso-Naphthylporphyrins while Interacting with DNA and Singlet Oxygen Generation.

PubMed

Hirakawa, Kazutaka; Taguchi, Makoto; Okazaki, Shigetoshi

2015-10-15

Electron donor-connecting cationic porphyrins meso-(1-naphthyl)-tris(N-methyl-p-pyridinio)porphyrin (1-NapTMPyP) and meso-(2-naphthyl)-tris(N-methyl-p-pyridinio)porphyrin (2-NapTMPyP) were designed and synthesized. DFT calculations speculate that the photoexcited states of 1- and 2-NapTMPyPs can be deactivated via intramolecular electron transfer from the naphthyl moiety to the porphyrin moiety. However, the quenching effect through the intramolecular electron transfer is insufficient, possibly due to the orthogonal position of the electron donor and the porphyrin ring and the relatively small driving force: Gibbs energies are 0.11 and 0.07 eV for 1- and 2-NapTMPyPs, respectively. It was speculated that more than 0.3 eV of the driving force is required to realize effective electron transfer in similar electron-donor connecting porphyrin systems. These porphyrins aggregated around the DNA strand, accelerating the deactivation of their excited singlet state and decreasing their photosensitized singlet oxygen-generating activities. In the presence of a sufficiently large concentration of DNA, these porphyrins can bind to a DNA strand stably, leading to an increased fluorescence quantum yield and lifetime. Singlet oxygen generation was also suppressed by the aggregation of porphyrins around DNA. Although the quantum yield of singlet oxygen generation was recovered in the presence of sufficient DNA, the singlet oxygen generated by DNA-binding porphyrins was significantly smaller than that without DNA. These results suggest that DNA-binding drugs limit the generation of photosensitized singlet oxygen by quenching the DNA strand.

Effect of CoQ homologues on reactive oxygen generation by mitochondria.

PubMed

Imada, Isuke; Sato, Eisuke F; Kira, Yukimi; Inoue, Masayasu

2008-01-01

Effect of CoQ compounds (Qs) on reactive oxygen (ROS) generation by mitochondrial complex I was studied using rat liver mitochondria and chemiluminescence probe L012. Kinetic analysis revealed that short chain Qs, such as Q2 and idebenone enhanced ROS generation by mitochondrial NADH oxidase system by a succinate-inhibitable mechanism. Lipid peroxidation in mitochondrial membranes induced by NADH and iron was inhibited by short chain Qs. The inhibitory activity was enhanced by co-oxidation of succinate as determined by chemiluminescence method and by electron spin resonance spectroscopy. These results suggested that the reduced form of short chain Qs inhibited mitochondrial ROS generation and lipid peroxidation.

Singlet-Oxygen Generation in Alkaline Periodate Solution.

PubMed

Bokare, Alok D; Choi, Wonyong

2015-12-15

A nonphotochemical generation of singlet oxygen ((1)O2) using potassium periodate (KIO4) in alkaline condition (pH > 8) was investigated for selective oxidation of aqueous organic pollutants. The generation of (1)O2 was initiated by the spontaneous reaction between IO4(-) and hydroxyl ions, along with a stoichiometric conversion of IO4(-) to iodate (IO3(-)). The reactivity of in-situ-generated (1)O2 was monitored by using furfuryl alcohol (FFA) as a model substrate. The formation of (1)O2 in the KIO4/KOH system was experimentally confirmed using electron spin resonance (ESR) measurements in corroboration with quenching studies using azide as a selective (1)O2 scavenger. The reaction in the KIO4/KOH solution in both oxic and anoxic conditions initiated the generation of superoxide ion as a precursor of the singlet oxygen (confirmed by using superoxide scavengers), and the presence of molecular oxygen was not required as a precursor of (1)O2. Although hydrogen peroxide had no direct influence on the FFA oxidation process, the presence of natural organic matter, such as humic and fulvic acids, enhanced the oxidation efficiency. Using the oxidation of simple organic diols as model compounds, the enhanced (1)O2 formation is attributed to periodate-mediated oxidation of vicinal hydroxyl groups present in humic and fulvic constituent moieties. The efficient and simple generation of (1)O2 using the KIO4/KOH system without any light irradiation can be employed for the selective oxidation of aqueous organic compounds under neutral and near-alkaline conditions.

Lanthanum(III)-catalyzed disproportionation of hydrogen peroxide: a heterogeneous generator of singlet molecular oxygen-1O2 (1Deltag)-in near-neutral aqueous and organic media for peroxidation of electron-rich substrates.

PubMed

Nardello, Véronique; Barbillat, Jacques; Marko, Jean; Witte, Peter T; Alsters, Paul L; Aubry, Jean-Marie

2003-01-20

The decomposition of hydrogen peroxide into singlet molecular oxygen-(1)O(2) ((1)Delta(g))-in the presence of lanthanum(iii) salts was studied by monitoring its characteristic IR luminescence at 1270 nm. The process was found to be heterogeneously catalyzed by La(III), provided that the heterogeneous catalyst is generated in situ. The yield of (1)O(2) generation was assessed as 45+/-5 % both in water and in methanol. The pH-dependence on the rate of (1)O(2) generation corresponds to a bell-shaped curve from pH 4.5 to 13 with a maximum around pH 8. The study of the influence of H(2)O(2) showed that the formation of (1)O(2) begins as soon as one equivalent of H(2)O(2) is introduced. It then increases drastically up to two equivalents and more smoothly above. Unlike all other metal salt catalyst systems known to date for H(2)O(2) disproportionation, this chemical source of (1)O(2) is able to generate (1)O(2) not only in basic media, but also under neutral and slightly acidic conditions. In addition, this La-based catalyst system has a very low tendency to induce unwanted oxygenating side reactions, such as epoxidation of alkenes. These two characteristics of the heterogeneous lanthanum catalyst system allow non-photochemical (i.e., "dark") singlet oxygenation of substrate classes that cannot be peroxidized successfully with conventional molybdate catalysts, such as allylic alcohols and alkenyl amines.

The electrochemical generation of useful chemical species from lunar materials

NASA Technical Reports Server (NTRS)

Tsai, Kan J.; Kuchynka, Daniel J.; Sammells, Anthony F.

1989-01-01

Electrochemical cells have been fabricated for the simultaneous generation of oxygen and lithium from a Li2O containing molten salt (Li2O-LiCl-LiF). The cell utilizes an oxygen vacancy conducting solid electrolyte, yttria-stabilized zirconia (YSZ), to effect separation between oxygen evolving and lithium reduction half-cell reactions. The cell, which operates at 700 to 850 C, possesses rapid electrode kinetics at the lithium-alloy electrode with exchange current density (i sub o) values being greater than 60mA sq cm. When used in the electrolytic mode, lithium produced at the negative electrode would be continuously removed from the cell for later use (under lunar conditions) as an easily storable reducing agent (compared to H2) for the chemical refining of lunar ores. Because of the high reversibility of this electrochemical system, it has also formed tha basis for the lithium oxygen secondary battery system which possesses the highest theoretical energy density yet investigated.

The electrochemical generation of useful chemical species from lunar materials

NASA Astrophysics Data System (ADS)

Tsai, Kan J.; Kuchynka, Daniel J.; Sammells, Anthony F.

1989-12-01

Electrochemical cells have been fabricated for the simultaneous generation of oxygen and lithium from a Li2O containing molten salt (Li2O-LiCl-LiF). The cell utilizes an oxygen vacancy conducting solid electrolyte, yttria-stabilized zirconia (YSZ), to effect separation between oxygen evolving and lithium reduction half-cell reactions. The cell, which operates at 700 to 850 C, possesses rapid electrode kinetics at the lithium-alloy electrode with exchange current density (i sub o) values being greater than 60mA sq cm. When used in the electrolytic mode, lithium produced at the negative electrode would be continuously removed from the cell for later use (under lunar conditions) as an easily storable reducing agent (compared to H2) for the chemical refining of lunar ores. Because of the high reversibility of this electrochemical system, it has also formed tha basis for the lithium oxygen secondary battery system which possesses the highest theoretical energy density yet investigated.

A Cabin Air Separator for EVA Oxygen

NASA Technical Reports Server (NTRS)

Graf, John C.

2011-01-01

Presently, the Extra-Vehicular Activities (EVAs) conducted from the Quest Joint Airlock on the International Space Station use high pressure, high purity oxygen that is delivered to the Space Station by the Space Shuttle. When the Space Shuttle retires, a new method of delivering high pressure, high purity oxygen to the High Pressure Gas Tanks (HPGTs) is needed. One method is to use a cabin air separator to sweep oxygen from the cabin air, generate a low pressure/high purity oxygen stream, and compress the oxygen with a multistage mechanical compressor. A main advantage to this type of system is that the existing low pressure oxygen supply infrastructure can be used as the source of cabin oxygen. ISS has two water electrolysis systems that deliver low pressure oxygen to the cabin, as well as chlorate candles and compressed gas tanks on cargo vehicles. Each of these systems can feed low pressure oxygen into the cabin, and any low pressure oxygen source can be used as an on-board source of oxygen. Three different oxygen separator systems were evaluated, and a two stage Pressure Swing Adsorption system was selected for reasons of technical maturity. Two different compressor designs were subjected to long term testing, and the compressor with better life performance and more favorable oxygen safety characteristics was selected. These technologies have been used as the basis of a design for a flight system located in Equipment Lock, and taken to Preliminary Design Review level of maturity. This paper describes the Cabin Air Separator for EVA Oxygen (CASEO) concept, describes the separator and compressor technology trades, highlights key technology risks, and describes the flight hardware concept as presented at Preliminary Design Review (PDR)

Plasma Assisted ISRU at Mars

NASA Technical Reports Server (NTRS)

Moses, Robert W.; Kuhl, Christopher A.; Templeton, Justin D.

2005-01-01

NASA's exploration goals for Mars and Beyond will require new power systems and in situ resource utilization (ISRU) technologies. Regenerative aerobraking may offer a revolutionary approach for in situ power generation and oxygen harvesting during these exploration missions. In theory, power and oxygen can be collected during aerobraking and stored for later use in orbit or on the planet. This technology would capture energy and oxygen from the plasma field that occurs naturally during hypersonic entry using well understood principles of magnetohydrodynamics and oxygen filtration. This innovative approach generates resources upon arrival at the operational site, and thus greatly differs from the traditional approach of taking everything you need with you from Earth. Fundamental analysis, computational fluid dynamics, and some testing of experimental hardware have established the basic feasibility of generating power during a Mars entry. Oxygen filtration at conditions consistent with spacecraft entry parameters at Mars has been studied to a lesser extent. Other uses of the MHD power are presented. This paper illustrates how some features of regenerative aerobraking may be applied to support human and robotic missions at Mars.

Investigation of the Makeup, Source, and Removal Strategies for Total Organic Carbon in the Oxygen Generation System Recirculation Loop

NASA Technical Reports Server (NTRS)

Bowman, Elizabeth M.; Carpenter, Joyce; Roy, Robert J.; Van Keuren, Steve; Wilson, Mark E.

2015-01-01

Since 2007, the Oxygen Generation System (OGS) on board the International Space Station (ISS) has been producing oxygen for crew respiration via water electrolysis. As water is consumed in the OGS recirculating water loop, make-up water is furnished by the ISS potable water bus. A rise in Total Organic Carbon (TOC) was observed beginning in February, 2011, which continues through the present date. Increasing TOC is of concern because the organic constituents responsible for the TOC were unknown and had not been identified; hence their impacts on the operation of the electrolytic cell stack components and on microorganism growth rates and types are unknown. Identification of the compounds responsible for the TOC increase, their sources, and estimates of their loadings in the OGA as well as possible mitigation strategies are presented.

Advancing the Oxygen Generation Assembly Design to Increase Reliability and Reduce Costs for a Future Long Duration Mission

NASA Technical Reports Server (NTRS)

Takada, Kevin C.; Ghariani, Ahmed E.; Van Keuren,

2015-01-01

The state-of-the-art Oxygen Generation Assembly (OGA) has been reliably producing breathing oxygen for the crew aboard the International Space Station (ISS) for over eight years. Lessons learned from operating the ISS OGA have led to proposing incremental improvements to advance the baseline design for use in a future long duration mission. These improvements are intended to reduce system weight, crew maintenance time and resupply mass from Earth while increasing reliability. The proposed improvements include replacing the cell stack membrane material, deleting the nitrogen purge equipment, replacing the hydrogen sensors, deleting the wastewater interface, replacing the hydrogen dome and redesigning the cell stack power supply. The development work to date will be discussed and forward work will be outlined. Additionally, a redesigned system architecture will be proposed.

77 FR 11418 - Airworthiness Directives; Various Transport Category Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-27

... oxygen generators in the lavatories until the generator oxygen supply is expended, or removing the oxygen generator(s); and, for each chemical oxygen generator, after the generator is expended (or removed... Floor, Room W12-140, 1200 New Jersey Avenue SE., Washington, DC 20590. Hand Delivery: Deliver to Mail...

21 CFR 868.5440 - Portable oxygen generator.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Portable oxygen generator. 868.5440 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5440 Portable oxygen generator. (a) Identification. A portable oxygen generator is a device that is intended to release oxygen for respiratory...

21 CFR 868.5440 - Portable oxygen generator.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Portable oxygen generator. 868.5440 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5440 Portable oxygen generator. (a) Identification. A portable oxygen generator is a device that is intended to release oxygen for respiratory...

21 CFR 868.5440 - Portable oxygen generator.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Portable oxygen generator. 868.5440 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5440 Portable oxygen generator. (a) Identification. A portable oxygen generator is a device that is intended to release oxygen for respiratory...

21 CFR 868.5440 - Portable oxygen generator.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Portable oxygen generator. 868.5440 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5440 Portable oxygen generator. (a) Identification. A portable oxygen generator is a device that is intended to release oxygen for respiratory...

21 CFR 868.5440 - Portable oxygen generator.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Portable oxygen generator. 868.5440 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5440 Portable oxygen generator. (a) Identification. A portable oxygen generator is a device that is intended to release oxygen for respiratory...

A New Approach for On-Demand Generation of Various Oxygen Tensions for In Vitro Hypoxia Models

PubMed Central

Li, Chunyan; Chaung, Wayne; Mozayan, Cameron; Chabra, Ranjeev; Wang, Ping; Narayan, Raj K.

2016-01-01

The development of in vitro disease models closely mimicking the functions of human disease has captured increasing attention in recent years. Oxygen tensions and gradients play essential roles in modulating biological systems in both physiologic and pathologic events. Thus, controlling oxygen tension is critical for mimicking physiologically relevant in vivo environments for cell, tissue and organ research. We present a new approach for on-demand generation of various oxygen tensions for in vitro hypoxia models. Proof-of-concept prototypes have been developed for conventional cell culture microplate by immobilizing a novel oxygen-consuming biomaterial on the 3D-printed insert. For the first time, rapid (~3.8 minutes to reach 0.5% O2 from 20.9% O2) and precisely controlled oxygen tensions/gradients (2.68 mmHg per 50 μm distance) were generated by exposing the biocompatible biomaterial to the different depth of cell culture media. In addition, changing the position of 3D-printed inserts with immobilized biomaterials relative to the cultured cells resulted in controllable and rapid changes in oxygen tensions (<130 seconds). Compared to the current technologies, our approach allows enhanced spatiotemporal resolution and accuracy of the oxygen tensions. Additionally, it does not interfere with the testing environment while maintaining ease of use. The elegance of oxygen tension manipulation introduced by our new approach will drastically improve control and lower the technological barrier of entry for hypoxia studies. Since the biomaterials can be immobilized in any devices, including microfluidic devices and 3D-printed tissues or organs, it will serve as the basis for a new generation of experimental models previously impossible or very difficult to implement. PMID:27219067

A New Approach for On-Demand Generation of Various Oxygen Tensions for In Vitro Hypoxia Models.

PubMed

Li, Chunyan; Chaung, Wayne; Mozayan, Cameron; Chabra, Ranjeev; Wang, Ping; Narayan, Raj K

2016-01-01

The development of in vitro disease models closely mimicking the functions of human disease has captured increasing attention in recent years. Oxygen tensions and gradients play essential roles in modulating biological systems in both physiologic and pathologic events. Thus, controlling oxygen tension is critical for mimicking physiologically relevant in vivo environments for cell, tissue and organ research. We present a new approach for on-demand generation of various oxygen tensions for in vitro hypoxia models. Proof-of-concept prototypes have been developed for conventional cell culture microplate by immobilizing a novel oxygen-consuming biomaterial on the 3D-printed insert. For the first time, rapid (~3.8 minutes to reach 0.5% O2 from 20.9% O2) and precisely controlled oxygen tensions/gradients (2.68 mmHg per 50 μm distance) were generated by exposing the biocompatible biomaterial to the different depth of cell culture media. In addition, changing the position of 3D-printed inserts with immobilized biomaterials relative to the cultured cells resulted in controllable and rapid changes in oxygen tensions (<130 seconds). Compared to the current technologies, our approach allows enhanced spatiotemporal resolution and accuracy of the oxygen tensions. Additionally, it does not interfere with the testing environment while maintaining ease of use. The elegance of oxygen tension manipulation introduced by our new approach will drastically improve control and lower the technological barrier of entry for hypoxia studies. Since the biomaterials can be immobilized in any devices, including microfluidic devices and 3D-printed tissues or organs, it will serve as the basis for a new generation of experimental models previously impossible or very difficult to implement.

Evidence that Singlet Oxygen-induced Human T Helper Cell Apoptosis Is the Basic Mechanism of Ultraviolet-A Radiation Phototherapy

PubMed Central

Morita, Akimichi; Werfel, Thomas; Stege, Helger; Ahrens, Constanze; Karmann, Karin; Grewe, Markus; Grether-Beck, Susanne; Ruzicka, Thomas; Kapp, Alexander; Klotz, Lars-Oliver; Sies, Helmut; Krutmann, Jean

1997-01-01

Ultraviolet A (UVA) irradiation is effectively used to treat patients with atopic dermatitis and other T cell mediated, inflammatory skin diseases. In the present study, successful phototherapy of atopic dermatitis was found to result from UVA radiation-induced apoptosis in skin-infiltrating T helper cells, leading to T cell depletion from eczematous skin. In vitro, UVA radiation-induced human T helper cell apoptosis was mediated through the FAS/FAS-ligand system, which was activated in irradiated T cells as a consequence of singlet oxygen generation. These studies demonstrate that singlet oxygen is a potent trigger for the induction of human T cell apoptosis. They also identify singlet oxygen generation as a fundamental mechanism of action operative in phototherapy. PMID:9362536

The effects of moisture on molecular sieve oxygen concentrators.

PubMed

Ikels, K G; Theis, C F

1985-01-01

Molecular sieve oxygen generating systems are receiving extensive laboratory and flight evaluation. Assessment of the molecular system has generally been conducted in the laboratory using clean dry air. In aircraft, however, the molecular sieve generator is supplied with engine bleed air which may not always be totally free of contaminants and water. Recent studies using bed washout technics have shown that the molecular sieve units, with 50% of the beds deactivated with water, still function normally with respect to product gas flow and O2 concentration. By utilizing the technics described in this paper, the moisture content or state of hydration of the molecular sieve can readily be determined.

Simulated altitude exposure assessment by hyperspectral imaging

NASA Astrophysics Data System (ADS)

Calin, Mihaela Antonina; Macovei, Adrian; Miclos, Sorin; Parasca, Sorin Viorel; Savastru, Roxana; Hristea, Razvan

2017-05-01

Testing the human body's reaction to hypoxia (including the one generated by high altitude) is important in aeronautic medicine. This paper presents a method of monitoring blood oxygenation during experimental hypoxia using hyperspectral imaging (HSI) and a spectral unmixing model based on a modified Beer-Lambert law. A total of 20 healthy volunteers (males) aged 25 to 60 years were included in this study. A line-scan HSI system was used to acquire images of the faces of the subjects. The method generated oxyhemoglobin and deoxyhemoglobin distribution maps from the foreheads of the subjects at 5 and 10 min of hypoxia and after recovery in a high oxygen breathing mixture. The method also generated oxygen saturation maps that were validated using pulse oximetry. An interesting pattern of desaturation on the forehead was discovered during the study, showing one of the advantages of using HSI for skin oxygenation monitoring in hypoxic conditions. This could bring new insight into the physiological response to high altitude and may become a step forward in air crew testing.

Simulated altitude exposure assessment by hyperspectral imaging.

PubMed

Calin, Mihaela Antonina; Macovei, Adrian; Miclos, Sorin; Parasca, Sorin Viorel; Savastru, Roxana; Hristea, Razvan

2017-05-01

Testing the human body’s reaction to hypoxia (including the one generated by high altitude) is important in aeronautic medicine. This paper presents a method of monitoring blood oxygenation during experimental hypoxia using hyperspectral imaging (HSI) and a spectral unmixing model based on a modified Beer–Lambert law. A total of 20 healthy volunteers (males) aged 25 to 60 years were included in this study. A line-scan HSI system was used to acquire images of the faces of the subjects. The method generated oxyhemoglobin and deoxyhemoglobin distribution maps from the foreheads of the subjects at 5 and 10 min of hypoxia and after recovery in a high oxygen breathing mixture. The method also generated oxygen saturation maps that were validated using pulse oximetry. An interesting pattern of desaturation on the forehead was discovered during the study, showing one of the advantages of using HSI for skin oxygenation monitoring in hypoxic conditions. This could bring new insight into the physiological response to high altitude and may become a step forward in air crew testing.

The F-16 Onboard Oxygen Generating System: Performance Evaluation and Man Rating

DTIC Science & Technology

1983-08-01

OXYGEN GENERATING , YSTEM: PERFORMANCE EVALUATION AND MAN RATING Thomas C. Horch , Captain, USAF Richard L. Miller, Ph.D. John B. Bomar, Jr...C. Horch , Capt, USAF; R. L. Miller, 8. CONTRACT OR GRANT NUMBER(i) Ph.D.; J. B. Bomar, Jr., Lt Col, IJSAF, BSC; J. B. Tedor, Maj, USAF, BSC; R. D...limitation (as of 1983); however, the information may no longer need protection since it is 14 years. At the time of its publication, Capt Thomas Horch

Hydrogen Purification and Recycling for an Integrated Oxygen Recovery System Architecture

NASA Technical Reports Server (NTRS)

Abney, Morgan B.; Greenwood, Zachary; Wall, Terry; Miller, Lee; Wheeler, Ray

2016-01-01

The United States Atmosphere Revitalization life support system on the International Space Station (ISS) performs several services for the crew including oxygen generation, trace contaminant control, carbon dioxide (CO2) removal, and oxygen recovery. Oxygen recovery is performed using a Sabatier reactor developed by Hamilton Sundstrand, wherein CO2 is reduced with hydrogen in a catalytic reactor to produce methane and water. The water product is purified in the Water Purification Assembly and recycled to the Oxygen Generation Assembly (OGA) to provide O2 to the crew. This architecture results in a theoretical maximum oxygen recovery from CO2 of approximately 54% due to the loss of reactant hydrogen in Sabatier-produced methane that is currently vented outside of ISS. Plasma Methane Pyrolysis technology (PPA), developed by Umpqua Research Company, provides the capability to further close the Atmosphere Revitalization oxygen loop by recovering hydrogen from Sabatier-produced methane. A key aspect of this technology approach is to purify the hydrogen from the PPA product stream which includes acetylene, unreacted methane and byproduct water and carbon monoxide. In 2015, four sub-scale hydrogen separation systems were delivered to NASA for evaluation. These included two electrolysis single-cell hydrogen purification cell stacks developed by Sustainable Innovations, LLC, a sorbent-based hydrogen purification unit using microwave power for sorbent regeneration developed by Umpqua Research Company, and a LaNi4.6Sn0.4 metal hydride produced by Hydrogen Consultants, Inc. Here we report the results of these evaluations, discuss potential architecture options, and propose future work.

Hydrogen Purification and Recycling for an Integrated Oxygen Recovery System Architecture

NASA Technical Reports Server (NTRS)

Abney, Morgan B.; Greenwood, Zachary; Wall, Terry; Nur, Mononita; Wheeler, Richard R., Jr.; Preston, Joshua; Molter, Trent

2016-01-01

The United States Atmosphere Revitalization life support system on the International Space Station (ISS) performs several services for the crew including oxygen generation, trace contaminant control, carbon dioxide (CO2) removal, and oxygen recovery. Oxygen recovery is performed using a Sabatier reactor developed by Hamilton Sundstrand, wherein CO2 is reduced with hydrogen in a catalytic reactor to produce methane and water. The water product is purified in the Water Purification Assembly and recycled to the Oxygen Generation Assembly (OGA) to provide O2 to the crew. This architecture results in a theoretical maximum oxygen recovery from CO2 of approx.54% due to the loss of reactant hydrogen in Sabatier-produced methane that is currently vented outside of ISS. Plasma Pyrolysis Assembly (PPA) technology, developed by Umpqua Research Company, provides the capability to further close the Atmosphere Revitalization oxygen loop by recovering hydrogen from Sabatier-produced methane. A key aspect of this technology approach is the need to purify the hydrogen from the PPA product stream which includes acetylene, unreacted methane and byproduct water and carbon monoxide. In 2015, four sub-scale hydrogen separation systems were delivered to NASA for evaluation. These included two electrolysis single-cell hydrogen purification cell stacks developed by Sustainable Innovations, LLC, a sorbent-based hydrogen purification unit using microwave power for sorbent regeneration developed by Umpqua Research Company, and a LaNi4.6Sn0.4 metal hydride produced by Hydrogen Consultants, Inc. Here we report the results of these evaluations to-date, discuss potential architecture options, and propose future work.

Oxygen Reduction Reaction on Graphene in an Electro-Fenton System: In Situ Generation of H2 O2 for the Oxidation of Organic Compounds.

PubMed

Chen, Chen-Yu; Tang, Cheng; Wang, Hao-Fan; Chen, Cheng-Meng; Zhang, Xiaoyuan; Huang, Xia; Zhang, Qiang

2016-05-23

Fenton oxidation using an aqueous mixture of Fe(2+) and H2 O2 is a promising environmental remediation strategy. However, the difficulty of storage and shipment of concentrated H2 O2 and the generation of iron sludge limit its broad application. Therefore, highly efficient and cost-effective electrocatalysts are in great need. Herein, a graphene catalyst is proposed for the electro-Fenton process, in which H2 O2 is generated in situ by the two-electron reduction of the dissolved O2 on the cathode and then decomposes to generate (.) OH in acidic solution with Fe(2+) . The π bond of the oxygen is broken whereas the σ bond is generally preserved on the metal-free reduced graphene oxide owing to the high free energy change. Consequently, the oxygen is reduced to H2 O2 through a two-electron pathway. The thermally reduced graphene with a high specific surface area (308.8 m(2)  g(-1) ) and a large oxygen content (10.3 at %) exhibits excellent reactivity for the two-electron oxygen reduction reaction to H2 O2 . A highly efficient peroxide yield (64.2 %) and a remarkable decolorization of methylene blue (12 mg L(-1) ) of over 97 % in 160 min are obtained. The degradation of methylene blue with hydroxyl radicals generated in situ is described by a pseudo first-order kinetics model. This provides a proof-of-concept of an environmentally friendly electro-Fenton process using graphene for the oxygen reduction reaction in an acidic solution to generate H2 O2 . © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hydrogen Generator

NASA Technical Reports Server (NTRS)

1978-01-01

Another spinoff from spacecraft fuel cell technology is the portable hydrogen generator shown. Developed by General Electric Company, it is an aid to safer operation of systems that use hydrogen-for example, gas chromatographs, used in laboratory analysis of gases. or flame ionization detectors used as $ollution monitors. The generator eliminates the need for high-pressure hydrogen storage bottles, which can be a safety hazard, in laboratories, hospitals and industrial plants. The unit supplies high-purity hydrogen by means of an electrochemical process which separates the hydrogen and oxygen in distilled water. The oxygen is vented away and the hydrogen gas is stored within the unit for use as needed. GE's Aircraft Equipment Division is producing about 1,000 of the generators annually.

Photosystems and global effects of oxygenic photosynthesis.

PubMed

Nelson, Nathan

2011-08-01

Because life on earth is governed by the second law of thermodynamics, it is subject to increasing entropy. Oxygenic photosynthesis, the earth's major producer of both oxygen and organic matter, is a principal player in the development and maintenance of life, and thus results in increased order. The primary steps of oxygenic photosynthesis are driven by four multi-subunit membrane protein complexes: photosystem I, photosystem II, cytochrome b(6)f complex, and F-ATPase. Photosystem II generates the most positive redox potential found in nature and thus capable of extracting electrons from water. Photosystem I generates the most negative redox potential found in nature; thus, it largely determines the global amount of enthalpy in living systems. The recent structural determination of PSII and PSI complexes from cyanobacteria and plants sheds light on the evolutionary forces that shaped oxygenic photosynthesis. This newly available structural information complements knowledge gained from genomic and proteomic data, allowing for a more precise description of the scenario in which the evolution of life systems took place. This article is part of a Special Issue entitled: Regulation of Electron Transport in Chloroplasts. Copyright © 2010 Elsevier B.V. All rights reserved.

OXYGEN TRANSPORT IN THE MICROCIRCULATION AND ITS REGULATION

PubMed Central

Pittman, Roland N.

2012-01-01

Cells require energy to carry out their functions and they typically use oxidative phosphorylation to generate the needed ATP. Thus, cells have a continuous need for oxygen which they receive by diffusion from the blood through the interstitial fluid. The circulatory system pumps oxygen-rich blood through a network of increasingly minute vessels, the microcirculation. The structure of the microcirculation is such that all cells have at least one nearby capillary for diffusive exchange of oxygen and red blood cells release the oxygen bound to hemoglobin as they traverse capillaries. This review focuses first on the historical development of techniques to measure oxygen at various sites in the microcirculation, including the blood, interstitium and cells. Next, approaches are described as to how these techniques have been employed to make discoveries about different aspects of oxygen transport. Finally, ways in which oxygen might participate in the regulation of blood flow toward matching oxygen supply to oxygen demand is discussed. Overall, the transport of oxygen to the cells of the body is one of the most critical functions of the cardiovascular system and it is in the microcirculation where the final local determinants of oxygen supply, oxygen demand and their regulation are decided. PMID:23025284

Alkaline static feed electrolyzer based oxygen generation system

NASA Technical Reports Server (NTRS)

Noble, L. D.; Kovach, A. J.; Fortunato, F. A.; Schubert, F. H.; Grigger, D. J.

1988-01-01

In preparation for the future deployment of the Space Station, an R and D program was established to demonstrate integrated operation of an alkaline Water Electrolysis System and a fuel cell as an energy storage device. The program's scope was revised when the Space Station Control Board changed the energy storage baseline for the Space Station. The new scope was aimed at the development of an alkaline Static Feed Electrolyzer for use in an Environmental Control/Life Support System as an oxygen generation system. As a result, the program was divided into two phases. The phase 1 effort was directed at the development of the Static Feed Electrolyzer for application in a Regenerative Fuel Cell System. During this phase, the program emphasized incorporation of the Regenerative Fuel Cell System design requirements into the Static Feed Electrolyzer electrochemical module design and the mechanical components design. The mechanical components included a Pressure Control Assembly, a Water Supply Assembly and a Thermal Control Assembly. These designs were completed through manufacturing drawing during Phase 1. The Phase 2 effort was directed at advancing the Alkaline Static Feed Electrolyzer database for an oxygen generation system. This development was aimed at extending the Static Feed Electrolyzer database in areas which may be encountered from initial fabrication through transportation, storage, launch and eventual Space Station startup. During this Phase, the Program emphasized three major areas: materials evaluation, electrochemical module scaling and performance repeatability and Static Feed Electrolyzer operational definition and characterization.

High-flow oxygen therapy: pressure analysis in a pediatric airway model.

PubMed

Urbano, Javier; del Castillo, Jimena; López-Herce, Jesús; Gallardo, José A; Solana, María J; Carrillo, Ángel

2012-05-01

The mechanism of high-flow oxygen therapy and the pressures reached in the airway have not been defined. We hypothesized that the flow would generate a low continuous positive pressure, and that elevated flow rates in this model could produce moderate pressures. The objective of this study was to analyze the pressure generated by a high-flow oxygen therapy system in an experimental model of the pediatric airway. An experimental in vitro study was performed. A high-flow oxygen therapy system was connected to 3 types of interface (nasal cannulae, nasal mask, and oronasal mask) and applied to 2 types of pediatric manikin (infant and neonatal). The pressures generated in the circuit, in the airway, and in the pharynx were measured at different flow rates (5, 10, 15, and 20 L/min). The experiment was conducted with and without a leak (mouth sealed and unsealed). Linear regression analyses were performed for each set of measurements. The pressures generated with the different interfaces were very similar. The maximum pressure recorded was 4 cm H(2)O with a flow of 20 L/min via nasal cannulae or nasal mask. When the mouth of the manikin was held open, the pressures reached in the airway and pharynxes were undetectable. Linear regression analyses showed a similar linear relationship between flow and pressures measured in the pharynx (pressure = -0.375 + 0.138 × flow) and in the airway (pressure = -0.375 + 0.158 × flow) with the closed mouth condition. According to our hypothesis, high-flow oxygen therapy systems produced a low-level CPAP in an experimental pediatric model, even with the use of very high flow rates. Linear regression analyses showed similar linear relationships between flow and pressures measured in the pharynx and in the airway. This finding suggests that, at least in part, the effects may be due to other mechanisms.

Plasma Assisted Combustion: Flame Regimes and Kinetic Studies

DTIC Science & Technology

2015-01-05

Kinetic model Fuel: Dimethyl ether Oxidizer= (1-x)O2 + xO3, x=0 - 0.1, p=1 atm Ozone chemistry & Dimethyl ether model ...diffusional cool flames • A heated counterflow burner integrated with vaporization system1 • n-heptane/nitrogen vs. oxygen/ ozone • Ozone generator...micro-DBD) produces 2- 5 % of ozone in oxygen stream, depending on oxygen flow rate • Speciation profiles by using a micro-probe sampling with a

Electrochemical oxygen concentrator as an oxygen compressor

NASA Technical Reports Server (NTRS)

1975-01-01

A solid polymer electrolyte (SPE) oxygen compressor is described which generates pressures of 3000 psi. The SPE is a cation exchange membrane with chemical compatibility, and has the capability of withstanding 5000 psi. Other features of the compressor described include: gasketless sealing, porus plate cell supports, and conductive cooling. Results are presented of a computer program which defines the power of the system as a function of density, temperature, pressure, membrane thickness, and water content.

14 CFR 25.1450 - Chemical oxygen generators.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Chemical oxygen generators. 25.1450 Section... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment Miscellaneous Equipment § 25.1450 Chemical oxygen generators. (a) For the purpose of this section, a chemical oxygen generator is defined as a...

14 CFR 25.1450 - Chemical oxygen generators.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Chemical oxygen generators. 25.1450 Section... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment Miscellaneous Equipment § 25.1450 Chemical oxygen generators. (a) For the purpose of this section, a chemical oxygen generator is defined as a...

Fuel and Food Are Not Made of Energy-- A Constructive View of Respiration and Combustion

ERIC Educational Resources Information Center

Ross, Keith

2013-01-01

We often say that food and fuels "contain" energy, whereas energy is stored in the fuel-oxygen system generated during photosynthesis. This article suggests revised approaches to teaching that make a clear distinction between matter (food, fuel, oxygen) and energy. (Contains 1 table, 5 boxes, and 6 figures.)

Magnetic nanoparticles: reactive oxygen species generation and potential therapeutic applications

NASA Astrophysics Data System (ADS)

Mai, Trang; Hilt, J. Zach

2017-07-01

Magnetic nanoparticles have been demonstrated to produce reactive oxygen species (ROS), which play a major role in various cellular pathways, via Fenton and Haber-Weiss reaction. ROS act as a double-edged sword inside the body. At normal conditions, the generation of ROS is in balance with their elimination by scavenger systems, and they can promote cell proliferation as well as differentiation. However, at an increased level, they can cause damages to protein, lead to cellular apoptosis, and contribute to many diseases including cancer. Many recent studies proposed a variety of strategies to either suppress toxicity of ROS generation or exploit the elevated ROS levels for cancer therapy.

Bosch Reactor Development for High Percentage Oxygen Recovery from Carbon Dioxide

NASA Technical Reports Server (NTRS)

Howard, David; Abney, Morgan

2015-01-01

This next Generation Life Support Project entails the development and demonstration of Bosch reaction technologies to improve oxygen recovery from metabolically generated oxygen and/or space environments. A primary focus was placed on alternate carbon formation reactor concepts to improve useful catalyst life for space vehicle applications, and make use of in situ catalyst resources for non-terrestrial surface missions. Current state-of-the-art oxygen recovery systems onboard the International Space Station are able to effectively recover approximately 45 percent of the oxygen consumed by humans and exhausted in the form of carbon dioxide (CO2). Excess CO2 is vented overboard and the oxygen contained in the molecules is lost. For long-duration missions beyond the reaches of Earth for resupply, it will be necessary to recover greater amounts of constituents such as oxygen that are necessary for sustaining life. Bosch technologies theoretically recover 100 percent of the oxygen from CO2, producing pure carbon as the sole waste product. Challenges with this technology revolve around the carbon product fouling catalyst materials, drastically limiting catalyst life. This project successfully demonstrated techniques to extend catalyst surface area exposure times to improve catalyst life for vehicle applications, and demonstrated the use of Martian and lunar regolith as viable catalyst Bosch Reactor Development for High Percentage Oxygen Recovery From Carbon Dioxide materials for surface missions. The Bosch process generates carbon nanotube formation within the regolith, which has been shown to improve mechanical properties of building materials. Production of bricks from post reaction regolith for building and radiation shielding applications were also explored.

Using the International Space Station (ISS) Oxygen Generation Assembly (OGA) Is Not Feasible for Mars Transit

NASA Technical Reports Server (NTRS)

Jones, Harry W.

2016-01-01

A review of two papers on improving the International Space Station (ISS) Oxygen Generation Assembly (OGA) shows that it would not save substantial mass on a Mars transit. The ISS OGA requires redesign for satisfactory operation, even for the ISS. The planned improvements of the OGA for ISS would not be sufficient to make it suitable for Mars, because Mars transit life support has significantly different requirements than ISS. The OGA for Mars should have lower mass, better reliability and maintainability, greater safety, radiation hardening, and capability for quiescent operation. NASA's methodical, disciplined systems engineering process should be used to develop the appropriate system.

A strategy for the prevention of protein oxidation by drug product in polymer-based syringes.

PubMed

Nakamura, Koji; Abe, Yoshihiko; Kiminami, Hideaki; Yamashita, Arisa; Iwasaki, Kazuhiro; Suzuki, Shigeru; Yoshino, Keisuke; Dierick, William; Constable, Kevin

2015-01-01

Recently, new and advanced ideas have been presented on the value of polymer-based syringes for improved safety, better strength, reduced aggregation, and the prevention of drug degradation. In this report, our findings on drug degradation from protein oxidation will be presented and discussed. Commonly, dissolved oxygen is one of the factors for causing protein degradation. Due to the nature of higher gas permeability in polymer-based syringes, it was thought to be difficult to control the oxygen level during storage. However, this report demonstrates the appropriateness of combining the use of an oxygen absorber within the secondary packaging as a deoxygenated packaging system. In addition, this report suggests that another factor to enhance protein oxidization is related to radicals on the syringe barrel from sterilization by irradiation. We demonstrate that steam sterilization can minimize protein oxidization, as the protein filled in steam sterilized syringe is much more stable. In conclusion, the main oxidation pathway of a protein has been identified as dissolved oxygen and radical generation within a polymer container. Possible solutions are herewith presented for controlling oxidation by means of applying a deoxygenated packaging system as well as utilizing steam sterilization as a method of sterilization for prefillable polymer syringes. There have been many presentations and discussions about the risks associated with glass prefilled syringes. Advanced ideas are being presented on the value of polymer-based syringes for improved safety, better strength, reduced protein aggregation, and the prevention of drug degradation. Drug degradation based on protein oxidation is discussed in this report. Identification of the main factors causing this degradation and possible solutions available by using polymer-based syringes will be presented. The causes of protein oxidation have been identified as dissolved oxygen and radicals generated by the applied method of sterilization. The oxidation reaction created by dissolved oxygen within the drug product can be effectively inhibited by controlling the removal of the oxygen through the use of a deoxygenated packaging system. This packaging system can control the level or complete removal of oxygen from the primary container and the secondary packaging system. Protein oxidation induced by the formation of radicals from sterilization by irradiation is another critical aspect where it was thought that various sterilization methods were acceptable without loosing drug product quality. However, this report is first to demonstrate that gamma sterilized polymer-based syringes accelerated protein oxidation by radical generation; this effect can be prevented by means of steam sterilization. © PDA, Inc. 2015.

Manipulation of Microenvironment with a Built-in Electrochemical Actuator in Proximity of a Dissolved Oxygen Microsensor

NASA Technical Reports Server (NTRS)

Kim, Chang-Soo; Lee, Cae-Hyang; Fiering, Jason O.; Ufer, Stefan; Scarantino, Charles W.; Nagle, H. Troy; Fiering, Jason O.; Ufer, Stefan; Nagle, H. Troy; Scarantino, Charles W.

2004-01-01

Abstract - Biochemical sensors for continuous monitoring require dependable periodic self- diagnosis with acceptable simplicity to check its functionality during operation. An in situ self- diagnostic technique for a dissolved oxygen microsensor is proposed in an effort to devise an intelligent microsensor system with an integrated electrochemical actuation electrode. With a built- in platinum microelectrode that surrounds the microsensor, two kinds of microenvironments, called the oxygen-saturated or oxygen-depleted phases, can be created by water electrolysis depending on the polarity. The functionality of the microsensor can be checked during these microenvironment phases. The polarographic oxygen microsensor is fabricated on a flexible polyimide substrate (Kapton) and the feasibility of the proposed concept is demonstrated in a physiological solution. The sensor responds properly during the oxygen-generating and oxygen- depleting phases. The use of these microenvironments for in situ self-calibration is discussed to achieve functional integration as well as structural integration of the microsensor system.

Introduction of water into the heme distal side by Leu65 mutations of an oxygen sensor, YddV, generates verdoheme and carbon monoxide, exerting the heme oxygenase reaction.

PubMed

Stranava, Martin; Martínková, Markéta; Stiborová, Marie; Man, Petr; Kitanishi, Kenichi; Muchová, Lucie; Vítek, Libor; Martínek, Václav; Shimizu, Toru

2014-11-01

The globin-coupled oxygen sensor, YddV, is a heme-based oxygen sensor diguanylate cyclase. Oxygen binding to the heme Fe(II) complex in the N-terminal sensor domain of this enzyme substantially enhances its diguanylate cyclase activity which is conducted in the C-terminal functional domain. Leu65 is located on the heme distal side and is important for keeping the stability of the heme Fe(II)-O2 complex by preventing the entry of the water molecule to the heme complex. In the present study, it was found that (i) Escherichia coli-overexpressed and purified L65N mutant of the isolated heme-bound domain of YddV (YddV-heme) contained the verdoheme iron complex and other modified heme complexes as determined by optical absorption spectroscopy and mass spectrometry; (ii) CO was generated in the reconstituted system composed of heme-bound L65N and NADPH:cytochrome P450 reductase as confirmed by gas chromatography; (iii) CO generation of heme-bound L65N in the reconstituted system was inhibited by superoxide dismutase and catalase. In a concordance with the result, the reactive oxygen species increased the CO generation; (iv) the E. coli cells overexpressing the L65N protein of YddV-heme also formed significant amounts of CO compared to the cells overexpressing the wild type protein; (v) generation of verdoheme and CO was also observed for other mutants at Leu65 as well, but to a lesser extent. Since Leu65 mutations are assumed to introduce the water molecule into the heme distal side of YddV-heme, it is suggested that the water molecule would significantly contribute to facilitating heme oxygenase reactions for the Leu65 mutants. Copyright © 2014 Elsevier Inc. All rights reserved.

Transport generated by mayfly nymphs to breathe

NASA Astrophysics Data System (ADS)

Chabreyrie, Rodolphe; Abdelaziz, Khaled; Balaras, Elias; Kiger, Kenneth

2014-11-01

In order to maintain their metabolism, many species of mayfly nymphs utilize an oscillating array of wing-shaped gills to augment extraction of dissolved oxygen from the surrounding water. As a nymph develops, the kinematics of these gills have been observed to abruptly change from a rowing-like to a flapping-like motion. To better understand the role of this abrupt kinematic change, we study the transport of dissolved oxygen, viewed as a passive scalar surrounding the gills, for an in-silico mayfly nymph. In particular, through a Lagrangian and stochastic dynamical systems approach, we simulate the advection and diffusion of this passive scalar, and reveal the key structures of the transport generated by the gills for both flapping and rowing kinematics. In this talk, we show how the switch from rowing to flapping enables the generation of a better transport skeleton (i.e. breading of Lagrangian Coherent Structures) and how such a transport skeleton influences the oxygen uptake.

On a clean power generation system with the co-gasification of biomass and coal in a quadruple fluidized bed gasifier.

PubMed

Yan, Linbo; He, Boshu

2017-07-01

A clean power generation system was built based on the steam co-gasification of biomass and coal in a quadruple fluidized bed gasifier. The chemical looping with oxygen uncoupling technology was used to supply oxygen for the calciner. The solid oxide fuel cell and the steam turbine were combined to generate power. The calcium looping and mineral carbonation were used for CO 2 capture and sequestration. The aim of this work was to study the characteristics of this system. The effects of key operation parameters on the system total energy efficiency (ŋ ten ), total exergy efficiency (ŋ tex ) and carbon sequestration rate (R cs ) were detected. The energy and exergy balance calculations were implemented and the corresponding Sankey and Grassmann diagrams were drawn. It was found that the maximum energy and exergy losses occurred in the steam turbine. The system ŋ ten and ŋ tex could be ∼50% and ∼47%, and R cs could be over unit. Copyright © 2017 Elsevier Ltd. All rights reserved.

Advanced chemical oxygen iodine lasers for novel beam generation

NASA Astrophysics Data System (ADS)

Wu, Kenan; Zhao, Tianliang; Huai, Ying; Jin, Yuqi

2018-03-01

Chemical oxygen iodine laser, or COIL, is an impressive type of chemical laser that emits high power beam with good atmospheric transmissivity. Chemical oxygen iodine lasers with continuous-wave plane wave output are well-developed and are widely adopted in directed energy systems in the past several decades. Approaches of generating novel output beam based on chemical oxygen iodine lasers are explored in the current study. Since sophisticated physical processes including supersonic flowing of gaseous active media, chemical reacting of various species, optical power amplification, as well as thermal deformation and vibration of mirrors take place in the operation of COIL, a multi-disciplinary model is developed for tracing the interacting mechanisms and evaluating the performance of the proposed laser architectures. Pulsed output mode with repetition rate as high as hundreds of kHz, pulsed output mode with low repetition rate and high pulse energy, as well as novel beam with vector or vortex feature can be obtained. The results suggest potential approaches for expanding the applicability of chemical oxygen iodine lasers.

Growth control of oxygen stoichiometry in homoepitaxial SrTiO3 films by pulsed laser epitaxy in high vacuum

PubMed Central

Lee, Ho Nyung; Ambrose Seo, Sung S.; Choi, Woo Seok; Rouleau, Christopher M.

2016-01-01

In many transition metal oxides, oxygen stoichiometry is one of the most critical parameters that plays a key role in determining the structural, physical, optical, and electrochemical properties of the material. However, controlling the growth to obtain high quality single crystal films having the right oxygen stoichiometry, especially in a high vacuum environment, has been viewed as a challenge. In this work, we show that, through proper control of the plume kinetic energy, stoichiometric crystalline films can be synthesized without generating oxygen defects even in high vacuum. We use a model homoepitaxial system of SrTiO3 (STO) thin films on single crystal STO substrates. Physical property measurements indicate that oxygen vacancy generation in high vacuum is strongly influenced by the energetics of the laser plume, and it can be controlled by proper laser beam delivery. Therefore, our finding not only provides essential insight into oxygen stoichiometry control in high vacuum for understanding the fundamental properties of STO-based thin films and heterostructures, but expands the utility of pulsed laser epitaxy of other materials as well. PMID:26823119

Total aerobic destruction of azo contaminants with nanoscale zero-valent copper at neutral pH: promotion effect of in-situ generated carbon center radicals.

PubMed

Dong, Guohui; Ai, Zhihui; Zhang, Lizhi

2014-12-01

In this study, nanoscale zero-valent copper (nZVC) was synthesized with a facile solvothermal method and used for the aerobic removal of azo contaminants at neutral pH for the first time. We found that both Cu(I) and OH generated during the nZVC induced molecular oxygen activation process accounted for the rapid total destruction of azo contaminants in the nZVC/Air system, where nZVC could activate molecular oxygen to produce H2O2, and also release Cu(I) to break the -NN- bond of azo contaminants via the sandmeyer reaction for the generation of carbon center radicals. The in-situ generated carbon center radicals would then react with OH produced by the Cu(I) catalyzed decomposition of H2O2, resulting in the generation of low molecular weight organic acids and their subsequent mineralization. The indispensible role of Cu(I) catalyzed sandmeyer reaction and the promotion effect of in-situ generated carbon center radicals on the rapid total destruction of azo contaminants in the nZVC/Air system were confirmed by gas chromatography-mass spectrometry analysis. This study can deepen our understanding on the degradation of organic pollutant with molecular oxygen activated by zero valent metal, and also provide a new method to remove azo contaminants at neutral pH. Copyright © 2014 Elsevier Ltd. All rights reserved.

Propulsion System Advances that Enable a Reusable Liquid Fly Back Booster (LFBB)

NASA Technical Reports Server (NTRS)

Keith, Edward L.; Rothschild, William J.

1998-01-01

This paper provides an overview of the booster propulsion system for the Liquid Fly Back Booster (LFBB). This includes, system requirements, design approach, concept of operations, reliability, safety and cost assumptions. The paper summarizes the findings of the Boeing propulsion team that has been studying the LFBB feasibility as a booster replacement for the Space Shuttle. This paper will discuss recent advances including a new generation of kerosene and oxygen rich pre-burner staged combustion cycle main rocket engines. The engine reliability and safety is expected to be much higher than current standards by adding extra operating margins into the design and normally operating the engines at 75% of engine rated power. This allows for engine out capability. The new generation of main engines operates at significantly higher chamber pressure than the prior generation of gas generator cycle engines. The oxygen rich pre-burner engine cycle, unlike the fuel rich gas generator cycle, results in internally self-cleaning firings which facilitates reusability. Maintenance is further enhanced with integrated health monitoring to improve safety and turn-around efficiency. The maintainability of the LFBB LOX / kerosene engines is being improved by designing the vehicle/engine interfaces for easy access to key engine components.

Propulsion system advances that enable a reusable Liquid Fly Back Booster (LFBB)

NASA Technical Reports Server (NTRS)

Keith, E. L.; Rothschild, W. J.

1998-01-01

This paper provides an overview of the booster propulsion system for the Liquid Fly Back Booster (LFBB). This includes, system requirements, design approach, concept of operations, reliability, safety and cost assumptions. The paper summarizes the findings of the Boeing propulsion team that has been studying the LFBB feasibility as a booster replacement for the Space Shuttle. This paper will discuss recent advances including a new generation of kerosene and oxygen rich pre-burner staged combustion cycle main rocket engines. The engine reliability and safety is expected to be much higher than current standards by adding extra operating margins into the design and normally operating the engines at 75% of engine rated power. This allows for engine out capability. The new generation of main engines operates at significantly higher chamber pressure than the prior generation of gas generator cycle engines. The oxygen rich pre-burner engine cycle, unlike the fuel rich gas generator cycle, results in internally self-cleaning firings which facilitates reusability. Maintenance is further enhanced with integrated health monitoring to improve safety and turn-around efficiency. The maintainability of the LFBB LOX/kerosene engines is being improved by designing the vehicle/engine interfaces for easy access to key engine components.

Fires in P-3 Aircraft Oxygen Systems

NASA Technical Reports Server (NTRS)

Stoltzfus, Joel

2006-01-01

Fires in three P3 aircraft oxygen systems have occurred: one in the Royal Australian Air Force (RAAF) in 1984 and two in the U.S. Navy in 1998 and 2003. All three fires started in the aluminum manifold and check valve (MCV) assembly and produced similar damages to the aircraft in which they occurred. This paper discusses a failure analysis conducted by the NASA Johnson Space Center White Sands Test Facility (WSTF) Oxygen Hazards and Testing Team on the 2003 U.S. Navy VP62 fire. It was surmised that the fire started due to heat generated by an oxygen leak past a silicone check valve seal or possibly because of particle impact near the seat of one of the MCV assembly check valves. An additional analysis of fires in several check valve poppet seals from other aircraft is discussed. These burned poppet seals came from P3 oxygen systems that had been serviced at the Naval Air Station (NAS) in Jacksonville following standard fill procedures. It was concluded that these seal fires occurred due to the heat from compression heating, particle impact, or the heat generated by an oxygen leak past the silicone check valve seal. The fact that catastrophic fires did not occur in the case of each check valve seal fire was attributed to the protective nature of the aluminum oxide layer on the check valve poppets. To prevent future fires of this nature, the U.S. and Canadian fleets of P3 aircraft have been retrofitted with MCV assemblies with an upgraded design and more burn-resistant materials.

A polydimethylsiloxane-polycarbonate hybrid microfluidic device capable of generating perpendicular chemical and oxygen gradients for cell culture studies.

PubMed

Chang, Chia-Wen; Cheng, Yung-Ju; Tu, Melissa; Chen, Ying-Hua; Peng, Chien-Chung; Liao, Wei-Hao; Tung, Yi-Chung

2014-10-07

This paper reports a polydimethylsiloxane-polycarbonate (PDMS-PC) hybrid microfluidic device capable of performing cell culture under combinations of chemical and oxygen gradients. The microfluidic device is constructed of two PDMS layers with microfluidic channel patterns separated by a thin PDMS membrane. The top layer contains an embedded PC film and a serpentine channel for a spatially confined oxygen scavenging chemical reaction to generate an oxygen gradient in the bottom layer for cell culture. Using the chemical reaction method, the device can be operated with a small amount of chemicals, without bulky gas cylinders and sophisticated flow control schemes. Furthermore, it can be directly used in conventional incubators with syringe pumps to simplify the system setup. The bottom layer contains arrangements of serpentine channels for chemical gradient generation and a cell culture chamber in the downstream. The generated chemical and oxygen gradients are experimentally characterized using a fluorescein solution and an oxygen-sensitive fluorescent dye, respectively. For demonstration, a 48 hour cell-based drug test and a cell migration assay using human lung adenocarcinoma epithelial cells (A549) are conducted under various combinations of the chemical and oxygen gradients in the experiments. The drug testing results show an increase in A549 cell apoptosis due to the hypoxia-activated cytotoxicity of tirapazamine (TPZ) and also suggest great cell compatibility and gradient controllability of the device. In addition, the A549 cell migration assay results demonstrate an aerotactic behavior of the A549 cells and suggest that the oxygen gradient plays an essential role in guiding cell migration. The migration results, under combinations of chemokine and oxygen gradients, cannot be simply superposed with single gradient results. The device is promising to advance the control of in vitro microenvironments, to better study cellular responses under various physiological conditions for biomedical applications.

Concurrent CO2 Control and O2 Generation for Advanced Life Support

NASA Technical Reports Server (NTRS)

Paul, Heather L.; Duncan, Keith L.; Hagelin-Weaver, Helena E.; Bishop, Sean R.; Wachsman, Eric D.

2007-01-01

The electrochemical reduction of carbon dioxide (CO2) using ceramic oxygen generators (COGs) is well known and widely studied, however, conventional devices using yttria-stabilized zirconia (YSZ) electrolytes operate at temperatures greater than 700 C. Operating at such high temperatures increases system mass compared to lower temperature systems because of increased energy overhead to get the COG up to operating temperature and the need for heavier insulation and/or heat exchangers to reduce the COG oxygen (O2) output temperature for comfortable inhalation. Recently, the University of Florida developed novel ceramic oxygen generators employing a bilayer electrolyte of gadolinia-doped ceria and erbia-stabilized bismuth for NASA's future exploration of Mars. To reduce landed mass and operation expenditures during the mission, in-situ resource utilization was proposed using these COGs to obtain both lifesupporting oxygen and oxidant/propellant fuel, by converting CO2 from the Mars atmosphere. The results showed that oxygen could be reliably produced from CO2 at temperatures as low as 400 C. These results indicate that this technology could be adapted to CO2 removal from a spacesuit and other applications in which CO2 removal was an issue. The strategy proposed for CO2 removal for advanced life support systems employs a catalytic layer combined with a COG so that it is reduced all the way to solid carbon and oxygen. Hence, a three-phased approach was used for the development of a viable low weight COG for CO2 removal. First, to reduce the COG operating temperature a high oxide ion conductivity electrolyte was developed. Second, to promote full CO2 reduction while avoiding the problem of carbon deposition on the COG cathode, novel cathodes and a removable catalytic carbon deposition layer were designed. Third, to improve efficiency, a pre-stage for CO2 absorption was used to concentrate CO2 from the exhalate before sending it to the COG. These subsystems were then integrated into a single CO2 removal system. This paper describes our progress to date on these tasks.

A sterilization system using ultraviolet photochemical reactions based on nitrous oxide and oxygen gases.

PubMed

Ohnishi, Yasutaka; Matsumoto, Hiroyuki; Iwamori, Satoru

2016-03-01

Active oxygen species (AOS) generated under ultraviolet (UV) lamps can be applied for various industrial processes owing to extremely strong oxidative abilities. We have already reported on an application of the AOS for a sterilization process of microorganisms. Here, a sterilization method using active oxygen generated under ultraviolet (UV) lamps introducing nitrous oxide (N2O) and oxygen gases into a vacuum chamber was investigated. Nitrogen dioxide (NO2) gas was readily produced from N2O by UV photochemical reactions under the low-pressure mercury lamp and then used to sterilize medical devices. We compared the ability of the N2O gas to sterilize Geobacillus stearothermophilus spores with those of conventional methods. Successful sterilization of spores on various biological indicators was achieved within 60 min, not only in sterilization bags but also in a lumen device. Copyright © 2016 Elsevier B.V. All rights reserved.

Cyanide oxidation by singlet oxygen generated via reaction between H2O2 from cathodic reduction and OCl(-) from anodic oxidation.

PubMed

Tian, Shichao; Li, Yibing; Zeng, Huabin; Guan, Wei; Wang, Yan; Zhao, Xu

2016-11-15

Cyanide is widely present in electroplating wastewater or metallurgical effluents. In the present study, the electrochemical destruction of cyanide with various anode and cathode compositions under alkaline conditions was investigated. The results indicated that the electrochemical system using RuO2/Ti as anode and activated carbon fiber (ACF) as cathode in the presence of sodium chloride was efficient for the cyanide removal. In this system, in situ generation of HClO by anodic oxidation of Cl(-) at RuO2/Ti anode occurred with the H2O2 generation by O2 reduction at ACF cathode. As confirmed by the electron spin resonance technique, the reaction between HClO and H2O2 led to the generation of singlet oxygen, which was responsible for the cyanide removal. Further experiment indicated that the cyanide removal efficiency increased with the increase of the current density or the sodium chloride concentration. Cyanate was identified as main product in the system. Besides, the system exhibited good stability for the cyanide removal, which was beneficial to its practical application. Copyright © 2016. Published by Elsevier Inc.

Evaluation of solid oxide fuel cell systems for electricity generation

NASA Technical Reports Server (NTRS)

Somers, E. V.; Vidt, E. J.; Grimble, R. E.

1982-01-01

Air blown (low BTU) gasification with atmospheric pressure Solid Electrolyte Fuel Cells (SOFC) and Rankine bottoming cycle, oxygen blown (medium BTU) gasification with atmospheric pressure SOFC and Rankine bottoming cycle, air blown gasification with pressurized SOFC and combined Brayton/Rankine bottoming cycle, oxygen blown gasification with pressurized SOFC and combined Brayton/Rankine bottoming cycle were evaluated.

Dependence of Initial Oxygen Concentration on Ozone Yield Using Inductive Energy Storage System Pulsed Power Generator

NASA Astrophysics Data System (ADS)

Go, Tomio; Tanaka, Yasushi; Yamazaki, Nobuyuki; Mukaigawa, Seiji; Takaki, Koichi; Fujiwara, Tamiya

Dependence of initial oxygen concentration on ozone yield using streamer discharge reactor driven by an inductive energy storage system pulsed power generator is described in this paper. Fast recovery type diodes were employed as semiconductor opening switch to interrupt a circuit current within 100 ns. This rapid current change produced high-voltage short pulse between a secondary energy storage inductor. The repetitive high-voltage short pulse was applied to a 1 mm diameter center wire electrode placed in a cylindrical pulse corona reactor. The streamer discharge successfully occurred between the center wire electrode and an outer cylinder ground electrode of 2 cm inner diameter. The ozone was produced with the streamer discharge and increased with increasing pulse repetition rate. The ozone yield changed in proportion to initial oxygen concentration contained in the injected gas mixture at 800 ns forward pumping time of the current. However, the decrease of the ozone yield by decreasing oxygen concentration in the gas mixture at 180 ns forward pumping time of the current was lower than the decrease at 800 ns forward pumping time of the current. This dependence of the initial oxygen concentration on ozone yield at 180 ns forward pumping time is similar to that of dielectric barrier discharge reactor.

Exhaust heated hydrogen and oxygen producing catalytic converter for combustion engine

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

Schreiber, E.T.

1977-07-26

A steam generator is provided in operative association with a source of water and the exhaust system of a combustion engine including an air induction system provided with primary fuel inlet structure and supplemental fuel inlet structure. The steam generator derives its heat for converting water into steam from the exhaust system of the combustion engine and the steam generator includes a steam outlet communicated with and opening into one end of an elongated tubular housing disposed in good heat transfer relation with the exhaust system of the combustion engine and having a gas outlet at its other end communicatedmore » with the supplemental fuel inlet of the induction system. The tubular housing has iron filings disposed therein and is in such heat transfer relation with the exhaust system of the combustion engine so as to elevate the temperature of steam passing therethrough and to heat the iron filings to the extent that passage of the heated steam over the heated filings will result in hydrogen and oxygen gas being produced in the tubular housing for subsequent passage to the supplemental fuel inlet of the combustion engine induction system.« less

Oxygen Production from Lunar Regolith using Ionic Liquids

NASA Technical Reports Server (NTRS)

Paley, Mark Steven; Karr, Laurel J.; Curreri, Peter

2009-01-01

The objective of this work and future follow-on work is to develop a safe, efficient, and recyclable method for oxygen and/or metals extraction from lunar regolith, in support of establishing a manned lunar outpost. The approach is to solubilize the oxides that comprise lunar regolith in media consisting of ionic liquids (ILs) and/or their mixtures at temperatures at or below 300 C. Once in solution, electrolysis can either be performed in-situ to generate oxygen at the anode and hydrogen and/or metals (silicon, iron, aluminum, titanium, etc.) at the cathode. Alternatively, the water that is generated during the solubilization process can be distilled out and condensed into a separate IL and then electrolysized to produce hydrogen and oxygen. In the case of lunar regolith, this method could theoretically produce 44g oxygen per 100g of regolith. The oxygen can be used for human life support and/or as an oxidizer for rocket fuels, and the metals can be used as raw materials for construction and/or device fabrication. Moreover, the hydrogen produced can be used to re-generate the acidic medium, which can then be used to process additional regolith, thereby making the materials recyclable and limiting upmass requirements. An important advantage of IL acid systems is that they are much "greener" and safer than conventional materials used for regolith processing such as sulfuric or hydrochloric acids. They have very low vapor pressures, which means that they contain virtually no toxic and/or flammable volatile content, they are relatively non-corrosive, and they can exhibit good stability in harsh environments (extreme temperatures, hard vacuum, etc.). Furthermore, regolith processing can be achieved at lower temperatures than other processes such as molten oxide electrolysis or hydrogen reduction, thereby reducing initial power requirements. Six ILs have been synthesized and tested for their capability to dissolve lunar simulant, and for electrochemical and thermal stability. The results showed that ILs can be very efficient electrolytes; in particular IL/phosphoric-acid mixtures appear extremely promising for solubilizing lunar simulant. Results from preliminary experiments for distillation of water produced from the oxygen within the metal oxides of the simulant and the hydrogen from the acid indicates that over 75% of the oxygen from the simulant can be harvested as water at a temperature of 150 C. A method for collection of oxygen from electrolysis of the water derived from solubilizing simulant was developed by using a liquid nitrogen trap to liquefy and collect the oxygen. Although precise quantification of the liquid oxygen trapped is difficult to obtain, the amount of hydrogen and oxygen collected from electrolysis of water in this system was greater than 98%. This set-up also included a portable mass spectrometer for the identification of gases released from electrolysis cells. Regeneration of ILs through re-protonation was also demonstrated. Four sequential re-generations of an IL following solubilization of simulant showed no significant differences in amounts of simulant dissolved. Follow-on work for this project should include more studies of IL/phosphoric acid systems. Also, much more work is necessary for defining methods for electrolysis and purification of metals from regolith solubilized in ILs, and for developing a system to use the produced hydrogen to regenerate the spent IL. Finally, design and development of flight breadboard and prototype hardware is required.

Automated Static Culture System Cell Module Mixing Protocol and Computational Fluid Dynamics Analysis

NASA Technical Reports Server (NTRS)

Kleis, Stanley J.; Truong, Tuan; Goodwin, Thomas J,

2004-01-01

This report is a documentation of a fluid dynamic analysis of the proposed Automated Static Culture System (ASCS) cell module mixing protocol. The report consists of a review of some basic fluid dynamics principles appropriate for the mixing of a patch of high oxygen content media into the surrounding media which is initially depleted of oxygen, followed by a computational fluid dynamics (CFD) study of this process for the proposed protocol over a range of the governing parameters. The time histories of oxygen concentration distributions and mechanical shear levels generated are used to characterize the mixing process for different parameter values.

High-Energy-Density Metal-Oxygen Batteries: Lithium-Oxygen Batteries vs Sodium-Oxygen Batteries.

PubMed

Song, Kyeongse; Agyeman, Daniel Adjei; Park, Mihui; Yang, Junghoon; Kang, Yong-Mook

2017-12-01

The development of next-generation energy-storage devices with high power, high energy density, and safety is critical for the success of large-scale energy-storage systems (ESSs), such as electric vehicles. Rechargeable sodium-oxygen (Na-O 2 ) batteries offer a new and promising opportunity for low-cost, high-energy-density, and relatively efficient electrochemical systems. Although the specific energy density of the Na-O 2 battery is lower than that of the lithium-oxygen (Li-O 2 ) battery, the abundance and low cost of sodium resources offer major advantages for its practical application in the near future. However, little has so far been reported regarding the cell chemistry, to explain the rate-limiting parameters and the corresponding low round-trip efficiency and cycle degradation. Consequently, an elucidation of the reaction mechanism is needed for both lithium-oxygen and sodium-oxygen cells. An in-depth understanding of the differences and similarities between Li-O 2 and Na-O 2 battery systems, in terms of thermodynamics and a structural viewpoint, will be meaningful to promote the development of advanced metal-oxygen batteries. State-of-the-art battery design principles for high-energy-density lithium-oxygen and sodium-oxygen batteries are thus reviewed in depth here. Major drawbacks, reaction mechanisms, and recent strategies to improve performance are also summarized. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solid-phase fullerene-like nanostructures as singlet oxygen photosensitizers in liquid media

NASA Astrophysics Data System (ADS)

Belousova, I. M.; Danilov, O. B.; Kiselev, V. M.; Kislyakov, I. M.; Kris'ko, T. K.; Murav'eva, T. D.; Videnichev, D. A.

2007-04-01

Singlet oxygen generation by fullerene and astralen containing surfaces and powders under visible irradiation was studied in water and organic liquids by means of 1Δ g state luminescence and chemical scavenger transmittance measurements. The chemical method, pioneered for solid photosensitizers of 10 II, allowed to measure the singlet oxygen concentration in the aqueous medium down to 10 8 cm -3. The singlet oxygen sensitizing by the solid-phase fullerene-containing systems was found to be 100 times less effective then by fullerene in solution. The results obtained confirm the applicability of these structures in biology and medicine.

Low-thrust chemical rocket engine study

NASA Technical Reports Server (NTRS)

Mellish, J. A.

1981-01-01

Engine data and information are presented to perform system studies on cargo orbit-transfer vehicles which would deliver large space structures to geosynchronous equatorial orbit. Low-thrust engine performance, weight, and envelope parametric data were established, preliminary design information was generated, and technologies for liquid rocket engines were identified. Two major engine design drivers were considered in the study: cooling and engine cycle options. Both film-cooled and regeneratively cooled engines were evaluated. The propellant combinations studied were hydrogen/oxygen, methane/oxygen, and kerosene/oxygen.

Closed Loop Control of Oxygen Delivery and Oxygen Generation

DTIC Science & Technology

2017-08-01

AFRL-SA-WP-SR-2017-0024 Closed Loop Control of Oxygen Delivery and Oxygen Generation Dr. Jay Johannigman1, Richard Branson1...for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO...TITLE AND SUBTITLE Closed Loop Control of Oxygen Delivery and Oxygen Generation 5a. CONTRACT NUMBER FA8650-10-2-6140 5b. GRANT NUMBER

An Oxidase-Based Electrochemical Fluidic Sensor with High-Sensitivity and Low-Interference by On-Chip Oxygen Manipulation

PubMed Central

Radhakrishnan, Nitin; Park, Jongwon; Kim, Chang-Soo

2012-01-01

Utilizing a simple fluidic structure, we demonstrate the improved performance of oxidase-based enzymatic biosensors. Electrolysis of water is utilized to generate bubbles to manipulate the oxygen microenvironment close to the biosensor in a fluidic channel. For the proper enzyme reactions to occur, a simple mechanical procedure of manipulating bubbles was developed to maximize the oxygen level while minimizing the pH change after electrolysis. The sensors show improved sensitivities based on the oxygen dependency of enzyme reaction. In addition, this oxygen-rich operation minimizes the ratio of electrochemical interference signal by ascorbic acid during sensor operation (i.e., amperometric detection of hydrogen peroxide). Although creatinine sensors have been used as the model system in this study, this method is applicable to many other biosensors that can use oxidase enzymes (e.g., glucose, alcohol, phenol, etc.) to implement a viable component for in-line fluidic sensor systems. PMID:23012527

Nickel-iron battery system safety

NASA Technical Reports Server (NTRS)

Saltat, R. C.

1984-01-01

The generated flow rates of gaseous hydrogen and gaseous oxygen from an electrical vehicle nickel-iron battery system were determined and used to evaluate the flame quenching capabilities of several candidate devices to prevent flame propagation within batteries having central watering/venting systems. The battery generated hydrogen and oxygen gases were measured for a complete charge and discharge cycle. The data correlates well with accepted theory during strong overcharge conditions indicating that the measurements are valid for other portions of the cycle. Tests confirm that the gas mixture in the cells is always flammable regardless of the battery status. The literature indicated that a conventional flame arrestor would not be effective over the broad spectrum of gassing conditions presented by a nickel-iron battery. Four different types of protective devices were evaluated. A foam-metal arrestor design was successful in quenching gaseous hydrogen and gaseous oxygen flames, however; the application of this flame arrestor to individual cell or module protection in a battery is problematic. A possible rearrangement of the watering/venting system to accept the partial protection of simple one-way valves is presented which, in combination with the successful foam-metal arrestor as main vent protection, could result in a significant improvement in battery protection.

Photolytically driven generation of dissolved oxygen and increased oxyhemoglobin in whole blood.

PubMed

Monzyk, Bruce F; Burckle, Eric C; Carleton, Linda M; Busch, James; Dasse, Kurt A; Martin, Peter M; Gilbert, Richard J

2006-01-01

The severely debilitating nature of chronic lung disease has long provided the impetus for the development of technologies to supplement the respiratory capacity of the human lung. Although conventional artificial lung technologies function by delivering pressurized oxygen to the blood through a system of hollow fibers or tubes, our approach uses photolytic energy to generate dissolved oxygen (DO) from the water already present in blood, thus eliminating the need for gas delivery. We have previously demonstrated that it is feasible to generate dissolved oxygen from water based on UVA illumination of a highly absorbent TiO2 thin film. In the current study, we extend this work by using photolytic energy to generate DO from whole blood, thus resulting in an increase of oxyhemoglobin as a function of back side TiO2 surface film illumination. Initial experiments, performed with Locke's Ringer solution, demonstrated effective film thickness and material selection for the conductive layer. The application of a small bias voltage was used to conduct photogenerated electrons from the aqueous phase to minimize electron recombination with the DO.Mixed arterial-venous bovine blood was flowed in a recirculating loop over TiO2 nanocrystalline films illuminated on the side opposite the blood (or "back side") to eliminate the possibility of any direct exposure of blood to light. After light exposure of the TiO2 film, the fraction of oxyhemoglobin in the blood rapidly increased to near saturation and remained stable throughout the trial period. Last, we evaluated potential biofouling of the DO generating surface by scanning electron microscopy, after photolytically energized DO generation in whole blood, and observed no white or red blood cell surface deposition, nor the accumulation of any other material at this magnification. We conclude that it is feasible to photolytically oxygenate the hemoglobin contained in whole blood with oxygen derived from the blood's own water content without involving a gaseous phase.

Development of ITM oxygen technology for integration in IGCC and other advanced power generation

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

Armstrong, Phillip A.

2015-03-31

Ion Transport Membrane (ITM) technology is based on the oxygen-ion-conducting properties of certain mixed-metal oxide ceramic materials that can separate oxygen from an oxygen-containing gas, such as air, under a suitable driving force. The “ITM Oxygen” air separation system that results from the use of such ceramic membranes produces a hot, pure oxygen stream and a hot, pressurized, oxygen-depleted stream from which significant amounts of energy can be extracted. Accordingly, the technology integrates well with other high-temperature processes, including power generation. Air Products and Chemicals, Inc., the Recipient, in conjunction with a dozen subcontractors, developed ITM Oxygen technology under thismore » five-phase Cooperative Agreement from the laboratory bench scale to implementation in a pilot plant capable of producing power and 100 tons per day (TPD) of purified oxygen. A commercial-scale membrane module manufacturing facility (the “CerFab”), sized to support a conceptual 2000 TPD ITM Oxygen Development Facility (ODF), was also established and operated under this Agreement. In the course of this work, the team developed prototype ceramic production processes and a robust planar ceramic membrane architecture based on a novel ceramic compound capable of high oxygen fluxes. The concept and feasibility of the technology was thoroughly established through laboratory pilot-scale operations testing commercial-scale membrane modules run under industrial operating conditions with compelling lifetime and reliability performance that supported further scale-up. Auxiliary systems, including contaminant mitigation, process controls, heat exchange, turbo-machinery, combustion, and membrane pressure vessels were extensively investigated and developed. The Recipient and subcontractors developed efficient process cycles that co-produce oxygen and power based on compact, low-cost ITMs. Process economics assessments show significant benefits relative to state-of-the-art cryogenic air separation technology in energy-intensive applications such as IGCC with and without carbon capture.« less

On Orbit ISS Oxygen Generation System Operation Status

NASA Technical Reports Server (NTRS)

Diderich, Greg S.; Polis, Pete; VanKeuren, Steven P.; Erickson, Robert; Mason, Richard

2011-01-01

The International Space Station (ISS) United States Orbital Segment (USOS) Oxygen Generation System (OGS) has accumulated almost a year of operation at varied oxygen production rates within the US Laboratory Module (LAB) since it was first activated in July 2007. It was operated intermittently through 2009 and 2010, due to filter clogging and acid accumulation in the recirculation loop. Since the installation of a deionizing bed in the recirculation loop in May of 2011 the OGA has been operated continuously. Filters in the recirculation loop have clogged and have been replaced. Hydrogen sensors have drifted apart, and a power failure may have condensed water on a hydrogen sensor. A pump delta pressure sensor failed, and a replacement new spare pump failed to start. Finally, the voltage across the cell stack increased out of tolerance due to cation contamination, and the cell stack was replaced. This paper will discuss the operating experience and characteristics of the OGS, as well as operational issues and their resolution.

A p-Type Zinc-Based Metal-Organic Framework.

PubMed

Shang, Congcong; Gautier, Romain; Jiang, Tengfei; Faulques, Eric; Latouche, Camille; Paris, Michael; Cario, Laurent; Bujoli-Doeuff, Martine; Jobic, Stéphane

2017-06-05

An original concept for the property tuning of semiconductors is demonstrated by the synthesis of a p-type zinc oxide (ZnO)-like metal-organic framework (MOF), (ZnC 2 O 3 H 2 ) n , which can be regarded as a possible alternative for ZnO, a natural n-type semiconductor. When small oxygen-rich organic linkers are introduced to the Zn-O system, oxygen vacancies and a deep valence-band maximum, the two obstacles for generating p-type behavior in ZnO, are restrained and raised, respectively. Further studies of this material on the doping and photoluminescence behaviors confirm its resemblance to metal oxides (MOs). This result answers the challenges of generating p-type behavior in an n-type-like system. This concept reveals that a new category of hybrid materials, with an embedded continuous metal-oxygen network, lies between the MOs and MOFs. It provides concrete support for the development of p-type hybrid semiconductors in the near future and, more importantly, the enrichment of tuning possibilities in inorganic semiconductors.

Study of the reaction of atomic oxygen with aerosols

NASA Technical Reports Server (NTRS)

Akers, F. I.; Wightman, J. P.

1975-01-01

The rate of disappearance of atomic oxygen was measured at several pressures in a fast flow pyrex reactor system with its walls treated with (NH4)2SO4 (s), H2SO4 (l), and NH4CL (s). Atomic oxygen, P-3 was generated by dissociation of pure, low pressure oxygen in a microwave discharge. Concentrations of atomic oxygen were measured at several stations in the reactor system using chemiluminescent titration with NO2. Recombination efficiencies calculated from experimentally determined wall recombination rate constants are in good agreement with reported values for clean Pyrex and an H2SO4 coated wall. The recombination efficiency for (NH4)2SO4, results in a slightly lower value than for H2S04. A rapid exothermic reaction between atomic oxygen and the NH4Cl wall coating prevented recombination efficiency determination for this coating. The results show that the technique is highly useful for wall recombination measurements and as a means of extrapolating to the case of free stream aerosol-gas interactions.

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

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-08

... Airworthiness Directives; Various Transport Category Airplanes Equipped With Chemical Oxygen Generators... the chemical oxygen generators in the lavatory. This AD was prompted by reports that the current design of these oxygen generators presents a hazard that could jeopardize flight safety. We are issuing...

Methods of producing epoxides from alkenes using a two-component catalyst system

DOEpatents

Kung, Mayfair C.; Kung, Harold H.; Jiang, Jian

2013-07-09

Methods for the epoxidation of alkenes are provided. The methods include the steps of exposing the alkene to a two-component catalyst system in an aqueous solution in the presence of carbon monoxide and molecular oxygen under conditions in which the alkene is epoxidized. The two-component catalyst system comprises a first catalyst that generates peroxides or peroxy intermediates during oxidation of CO with molecular oxygen and a second catalyst that catalyzes the epoxidation of the alkene using the peroxides or peroxy intermediates. A catalyst system composed of particles of suspended gold and titanium silicalite is one example of a suitable two-component catalyst system.

A Survey of Alternative Oxygen Production Technologies

NASA Technical Reports Server (NTRS)

Lueck, Dale E.; Parrish, Clyde F.; Buttner, William J.; Surma, Jan M.; Delgado, H. (Technical Monitor)

2001-01-01

Utilization of the Martian atmosphere for the production of fuel and oxygen has been extensively studied. The baseline fuel production process is a Sabatier reactor, which produces methane and water from carbon dioxide and hydrogen. The oxygen produced from the electrolysis of the water is only half of that needed for methane-based rocket propellant, and additional oxygen is needed for breathing air, fuel cells and other energy sources. Zirconia electrolysis cells for the direct reduction of CO2 arc being developed as an alternative means of producing oxygen, but present many challenges for a large-scale oxygen production system. The very high operating temperatures and fragile nature of the cells coupled with fairly high operating voltages leave room for improvement. This paper will survey alternative oxygen production technologies, present data on operating characteristics, materials of construction, and some preliminary laboratory results on attempts to implement each. Our goal is to significantly improve upon the characteristics of proposed zirconia cells for oxygen production. To achieve that goal we are looking at electrolytic systems that operate at significantly lower temperatures, preferably below 31C to allow the incorporation of liquid CO2 in the electrolyte. Our preliminary results indicate that such a system will have much higher current densities and have simpler cathode construction than a porous gas feed electrode system. Such a system could be achieved based on nonaqueous electrolytes or ionic liquids. We are focusing our research on the anode reaction that will produce oxygen from a product generated at the cathode using CO2 as the feed. Operation at low temperatures also will open up the full range of polymer and metal materials, allowing a more robust system design to withstand the rigors of flight, landing, and long term unattended operation on the surface of Mars.

Technology Innovations from NASA's Next Generation Launch Technology Program

NASA Technical Reports Server (NTRS)

Cook, Stephen A.; Morris, Charles E. K., Jr.; Tyson, Richard W.

2004-01-01

NASA's Next Generation Launch Technology Program has been on the cutting edge of technology, improving the safety, affordability, and reliability of future space-launch-transportation systems. The array of projects focused on propulsion, airframe, and other vehicle systems. Achievements range from building miniature fuel/oxygen sensors to hot-firings of major rocket-engine systems as well as extreme thermo-mechanical testing of large-scale structures. Results to date have significantly advanced technology readiness for future space-launch systems using either airbreathing or rocket propulsion.

Singlet oxygen generation on porous superhydrophobic surfaces: effect of gas flow and sensitizer wetting on trapping efficiency.

PubMed

Zhao, Yuanyuan; Liu, Yang; Xu, Qianfeng; Barahman, Mark; Bartusik, Dorota; Greer, Alexander; Lyons, Alan M

2014-11-13

We describe physical-organic studies of singlet oxygen generation and transport into an aqueous solution supported on superhydrophobic surfaces on which silicon-phthalocyanine (Pc) particles are immobilized. Singlet oxygen ((1)O2) was trapped by a water-soluble anthracene compound and monitored in situ using a UV-vis spectrometer. When oxygen flows through the porous superhydrophobic surface, singlet oxygen generated in the plastron (i.e., the gas layer beneath the liquid) is transported into the solution within gas bubbles, thereby increasing the liquid-gas surface area over which singlet oxygen can be trapped. Higher photooxidation rates were achieved in flowing oxygen, as compared to when the gas in the plastron was static. Superhydrophobic surfaces were also synthesized so that the Pc particles were located in contact with, or isolated from, the aqueous solution to evaluate the relative effectiveness of singlet oxygen generated in solution and the gas phase, respectively; singlet oxygen generated on particles wetted by the solution was trapped more efficiently than singlet oxygen generated in the plastron, even in the presence of flowing oxygen gas. A mechanism is proposed that explains how Pc particle wetting, plastron gas composition and flow rate as well as gas saturation of the aqueous solution affect singlet oxygen trapping efficiency. These stable superhydrophobic surfaces, which can physically isolate the photosensitizer particles from the solution may be of practical importance for delivering singlet oxygen for water purification and medical devices.

Autoamplificatory singlet oxygen generation sensitizes tumor cells for intercellular apoptosis-inducing signaling.

PubMed

Bauer, Georg

2018-06-01

Tumor cells express NADPH oxidase-1 (NOX1) in their membrane and control NOX1-based intercellular reactive oxygen and nitrogen species (ROS/RNS)-dependent apoptosis-inducing signaling through membrane-associated catalase and superoxide dismutase. of tumor cells with high concentrations of H 2 O 2 , peroxnitrite, HOCl, or increasing the concentration of cell-derived NO causes initial generation of singlet oxygen and local inactivation of membrane-associated catalase. As a result, free peroxynitrite and H 2 O 2 interact and generate secondary singlet oxygen. Inactivation of further catalase molecules by secondary singlet oxygen leads to auto-amplification of singlet oxygen generation and catalase inactivation. This allows reactivation of intercellular ROS/RNS-signaling and selective apoptosis induction in tumor cells. The initial singlet oxygen generation seems to be the critical point in this complex biochemical multistep mechanism. Initial singlet oxygen generation requires the interaction between distinct tumor cell-derived ROS and RNS and may also depend on either the induction of NO synthase expression or NOX1 activation through the FAS receptor. FAS receptor activation can be achieved by singlet oxygen. Autoamplificatory generation of singlet oxygen through the interaction between peroxynitrite and hydrogen peroxide inherits a rich potential for the establishment of synergistic effects that may be instrumental for novel approaches of tumor therapy with high selectivity towards malignant cells. Copyright © 2017 Elsevier B.V. All rights reserved.

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

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-09

... the supplemental oxygen supply can also complicate activating the oxygen flow, since that is generally... oxygen quantity requirements of Sec. 25.1443, Minimum mass flow of supplemental oxygen. E. Related...-0812; Notice No. 13-01] RIN 2120-AK14 Requirements for Chemical Oxygen Generators Installed on...

Online Oxide Contamination Measurement and Purification Demonstration

NASA Technical Reports Server (NTRS)

Bradley, D. E.; Godfroy, T. J.; Webster, K. L.; Garber, A. E.; Polzin, K. A.; Childers, D. J.

2011-01-01

Liquid metal sodium-potassium (NaK) has advantageous thermodynamic properties indicating its use as a fission reactor coolant for a surface (lunar, martian) power system. A major area of concern for fission reactor cooling systems is system corrosion due to oxygen contaminants at the high operating temperatures experienced. A small-scale, approximately 4-L capacity, simulated fission reactor cooling system employing NaK as a coolant was fabricated and tested with the goal of demonstrating a noninvasive oxygen detection and purification system. In order to generate prototypical conditions in the simulated cooling system, several system components were designed, fabricated, and tested. These major components were a fully-sealed, magnetically-coupled mechanical NaK pump, a graphite element heated reservoir, a plugging indicator system, and a cold trap. All system components were successfully demonstrated at a maximum system flow rate of approximately 150 cc/s at temperatures up to 550 C. Coolant purification was accomplished using a cold trap before and after plugging operations which showed a relative reduction in oxygen content.

A conceptual design of catalytic gasification fuel cell hybrid power plant with oxygen transfer membrane

NASA Astrophysics Data System (ADS)

Shi, Wangying; Han, Minfang

2017-09-01

A hybrid power generation system integrating catalytic gasification, solid oxide fuel cell (SOFC), oxygen transfer membrane (OTM) and gas turbine (GT) is established and system energy analysis is performed. In this work, the catalytic gasifier uses steam, recycled anode off-gas and pure oxygen from OTM system to gasify coal, and heated by hot cathode off-gas at the same time. A zero-dimension SOFC model is applied and verified by fitting experimental data. Thermodynamic analysis is performed to investigate the integrated system performance, and system sensitivities on anode off-gas back flow ratio, SOFC fuel utilization, temperature and pressure are discussed. Main conclusions are as follows: (1) System overall electricity efficiency reaches 60.7%(HHV) while the gasifier operates at 700 °C and SOFC at 850 °C with system pressure at 3.04 bar; (2) oxygen enriched combustion simplify the carbon-dioxide capture process, which derives CO2 of 99.2% purity, but results in a penalty of 6.7% on system electricity efficiency; (3) with SOFC fuel utilization or temperature increasing, the power output of SOFC increases while GT power output decreases, and increasing system pressure can improve both the performance of SOFC and GT.

Hawaii Energy and Environmental Technologies Initiative

DTIC Science & Technology

2005-06-01

include a hydrate synthesis system, benthic pressure chambers to simulate deep seafloor sediment, and specialized instrumentation for high pressure...the high probability that a sulfide/oxygen microbial fuel cell can generate electricity in deep ocean sediments, and that prolonged power generation may...hydrogen generation (using an electrolyser) and storage, and on-line high -resolution gas analysis. In addition to installation and commissioning of

Peroxide-based oxygen generating topical wound dressing for enhancing healing of dermal wounds.

PubMed

Chandra, Prafulla K; Ross, Christina L; Smith, Leona C; Jeong, Seon S; Kim, Jaehyun; Yoo, James J; Harrison, Benjamin S

2015-01-01

Oxygen generating biomaterials represent a new trend in regenerative medicine that aims to generate and supply oxygen at the site of requirement, to support tissue healing and regeneration. To enhance the healing of dermal wounds, we have developed a highly portable, in situ oxygen generating wound dressings that uses sodium percarbonate (SPO) and calcium peroxide (CPO) as chemical oxygen sources. The dressing continuously generated oxygen for more than 3 days, after which it was replaced. In the in vivo testing on porcine full-thickness porcine wound model, the SPO/CPO dressing showed enhanced wound healing during the 8 week study period. Quantitative measurements of wound healing related parameters, such as wound closure, reepithelialization, epidermal thickness and collagen content of dermis showed that supplying oxygen topically using the SPO/CPO dressing significantly accelerated the wound healing. An increase in neovascularization, as determined using Von Willebrand factor (vWF) and CD31 staining, was also observed in the presence of SPO/CPO dressing. This novel design for a wound dressing that contains oxygen generating biomaterials (SPO/CPO) for supplying topical oxygen, may find utility in treating various types of acute to chronic wounds. © 2015 by the Wound Healing Society.

Singlet Oxygen Generation by Cyclometalated Complexes and Applications†

PubMed Central

Ashen-Garry, David; Selke, Matthias

2014-01-01

While cyclometalated complexes have been extensively studied for optoelectronic applications, these compounds also represent a relatively new class of photosensitizers for the production of singlet oxygen. Thus far, singlet oxygen generation from cyclometalated Ir and Pt complexes has been studied in detail. In this review, photophysical data for singlet oxygen generation from these complexes is presented, and the mechanism of 1O2 generation is discussed, including evidence for singlet oxygen generation via an electron transfer mechanism for some of cyclometalated Ir complexes. The period from the first report of singlet oxygen generation by a cyclometalated Ir complex in 2002 through August 2013 is covered in this review. This new class of singlet oxygen photosensitizers may prove to be rather versatile due to the ease of substitution of ancillary ligands without loss of activity. Several cyclometalated complexes have been tethered to zeolites, polystyrene, or quantum dots. Applications for photooxygenation of organic molecules, including “traditional” singlet oxygen reactions (ene reaction, [4+2] and [2+2] cycloadditions) as well as oxidative coupling of amines are presented. Potential biomedical applications are also reviewed. PMID:24344628

Singlet oxygen generation by cyclometalated complexes and applications.

PubMed

Ashen-Garry, David; Selke, Matthias

2014-01-01

While cyclometalated complexes have been extensively studied for optoelectronic applications, these compounds also represent a relatively new class of photosensitizers for the production of singlet oxygen. Thus far, singlet oxygen generation from cyclometalated Ir and Pt complexes has been studied in detail. In this review, photophysical data for singlet oxygen generation from these complexes are presented, and the mechanism of (1) O2 generation is discussed, including evidence for singlet oxygen generation via an electron-transfer mechanism for some of cyclometalated Ir complexes. The period from the first report of singlet oxygen generation by a cyclometalated Ir complex in 2002 through August 2013 is covered in this review. This new class of singlet oxygen photosensitizers may prove to be rather versatile due to the ease of substitution of ancillary ligands without loss of activity. Several cyclometalated complexes have been tethered to zeolites, polystyrene, or quantum dots. Applications for photooxygenation of organic molecules, including "traditional" singlet oxygen reactions (ene reaction, [4 + 2] and [2 + 2] cycloadditions) as well as oxidative coupling of amines are presented. Potential biomedical applications are also reviewed. © 2013 The American Society of Photobiology.

Electrochemical Hydrogen Peroxide Generator

NASA Technical Reports Server (NTRS)

Tennakoon, Charles L. K.; Singh, Waheguru; Anderson, Kelvin C.

2010-01-01

Two-electron reduction of oxygen to produce hydrogen peroxide is a much researched topic. Most of the work has been done in the production of hydrogen peroxide in basic media, in order to address the needs of the pulp and paper industry. However, peroxides under alkaline conditions show poor stabilities and are not useful in disinfection applications. There is a need to design electrocatalysts that are stable and provide good current and energy efficiencies to produce hydrogen peroxide under acidic conditions. The innovation focuses on the in situ generation of hydrogen peroxide using an electrochemical cell having a gas diffusion electrode as the cathode (electrode connected to the negative pole of the power supply) and a platinized titanium anode. The cathode and anode compartments are separated by a readily available cation-exchange membrane (Nafion 117). The anode compartment is fed with deionized water. Generation of oxygen is the anode reaction. Protons from the anode compartment are transferred across the cation-exchange membrane to the cathode compartment by electrostatic attraction towards the negatively charged electrode. The cathode compartment is fed with oxygen. Here, hydrogen peroxide is generated by the reduction of oxygen. Water may also be generated in the cathode. A small amount of water is also transported across the membrane along with hydrated protons transported across the membrane. Generally, each proton is hydrated with 3-5 molecules. The process is unique because hydrogen peroxide is formed as a high-purity aqueous solution. Since there are no hazardous chemicals or liquids used in the process, the disinfection product can be applied directly to water, before entering a water filtration unit to disinfect the incoming water and to prevent the build up of heterotrophic bacteria, for example, in carbon based filters. The competitive advantages of this process are: 1. No consumable chemicals are needed in the process. The only raw materials needed are water and oxygen or air. 2. The product is pure and can therefore be used in disinfection applications directly or after proper dilution with water. 3. Oxygen generated in the anode compartment is used in the electrochemical reduction process; in addition, external oxygen is used to establish a high flow rate in the cathode compartment to remove the desired product efficiently. Exiting oxygen can be recycled after separation of liquid hydrogen peroxide product, if so desired. 4. The process can be designed for peroxide generation under microgravity conditions. 5. High concentrations of the order of 6-7 wt% can be generated by this method. This method at the time of this reporting is superior to what other researchers have reported. 6. The cell design allows for stacking of cells to increase the hydrogen peroxide production. 7. The catalyst mix containing a diquaternary ammonium compound enabled not only higher concentration of hydrogen peroxide but also higher current efficiency, improved energy efficiency, and catalyst stability. 8. The activity of the catalyst is maintained even after repeated periods of system shutdown. 9. The catalyst system can be extended for fuel-cell cathodes with suitable modifications.

Micro Chemical Oxygen-Iodine Laser (COIL)

DTIC Science & Technology

2007-10-01

required to form a good o-ring seal. Steam generator design A pumping system based on steam ejectors was designed during the course of the previous HEL-JTO...options for the steam generator design . The first is to catalyze the decomposition of hydrogen peroxide through the use of a standard solid

Recovery Act: Novel Oxygen Carriers for Coal-fueled Chemical Looping

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

Pan, Wei-Ping; Cao, Yan

2012-11-30

Chemical Looping Combustion (CLC) could totally negate the necessity of pure oxygen by using oxygen carriers for purification of CO{sub 2} stream during combustion. It splits the single fuel combustion reaction into two linked reactions using oxygen carriers. The two linked reactions are the oxidation of oxygen carriers in the air reactor using air, and the reduction of oxygen carriers in the fuel reactor using fuels (i.e. coal). Generally metal/metal oxides are used as oxygen carriers and operated in a cyclic mode. Chemical looping combustion significantly improves the energy conversion efficiency, in terms of the electricity generation, because it improvesmore » the reversibility of the fuel combustion process through two linked parallel processes, compared to the conventional combustion process, which is operated far away from its thermo-equilibrium. Under the current carbon-constraint environment, it has been a promising carbon capture technology in terms of fuel combustion for power generation. Its disadvantage is that it is less mature in terms of technological commercialization. In this DOE-funded project, accomplishment is made by developing a series of advanced copper-based oxygen carriers, with properties of the higher oxygen-transfer capability, a favorable thermodynamics to generate high purity of CO{sub 2}, the higher reactivity, the attrition-resistance, the thermal stability in red-ox cycles and the achievement of the auto-thermal heat balance. This will be achieved into three phases in three consecutive years. The selected oxygen carriers with final-determined formula were tested in a scaled-up 10kW coal-fueled chemical looping combustion facility. This scaled-up evaluation tests (2-day, 8-hour per day) indicated that, there was no tendency of agglomeration of copper-based oxygen carriers. Only trace-amount of coke or carbon deposits on the copper-based oxygen carriers in the fuel reactor. There was also no evidence to show the sulphidization of oxygen carriers in the system by using the high-sulfur-laden asphalt fuels. In all, the scaled-up test in 10 kW CLC facility demonstrated that the preparation method of copper-based oxygen carrier not only help to maintain its good reactivity, also largely minimize its agglomeration tendency.« less

Growth control of oxygen stoichiometry in homoepitaxial SrTiO 3 films by pulsed laser epitaxy in high vacuum

DOE PAGES

Lee, Ho Nyung; Ambrose Seo, Sung S.; Choi, Woo Seok; ...

2016-01-29

In many transition metal oxides, oxygen stoichiometry is one of the most critical parameters that plays a key role in determining the structural, physical, optical, and electrochemical properties of the material. However, controlling the growth to obtain high quality single crystal films having the right oxygen stoichiometry, especially in a high vacuum environment, has been viewed as a challenge. In this work, we show that, through proper control of the plume kinetic energy, stoichiometric crystalline films can be synthesized without generating oxygen defects even in high vacuum. We use a model homoepitaxial system of SrTiO 3 (STO) thin films onmore » single crystal STO substrates. Physical property measurements indicate that oxygen vacancy generation in high vacuum is strongly influenced by the energetics of the laser plume, and it can be controlled by proper laser beam delivery. Thus, our finding not only provides essential insight into oxygen stoichiometry control in high vacuum for understanding the fundamental properties of STO-based thin films and heterostructures, but it expands the utility of pulsed laser epitaxy of other materials as well.₃« less

The analysis of parameters of the cryogenic oxygen unit cooperating with power plant to realize oxy-fuel combustion

NASA Astrophysics Data System (ADS)

Hnydiuk-Stefan, Anna; Składzień, Jan

2015-03-01

The paper examines from the thermodynamic point of view operation of coal fired power unit cooperating with the cryogenic oxygen unit, with a particular emphasis on the characteristic performance parameters of the oxygen unit. The relatively high purity technical oxygen produced in the oxygen unit is then used as the oxidant in the fluidized bed boiler of the modern coal fired power unit with electric power output of approximately 460 MW. The analyzed oxygen unit has a classical two-column structure with an expansion turbine (turboexpander), which allows the use of relatively low pressure initially compressed air. Multivariant calculations were performed, the main result being the loss of power and efficiency of the unit due to the need to ensure adequate driving power to the compressor system of the oxygen generating plant.

Free radical generation in the brain precedes hyperbaric oxygen-induced convulsions.

PubMed

Torbati, D; Church, D F; Keller, J M; Pryor, W A

1992-01-01

We tested the hypothesis that hyperbaric oxygenation (HBO) generates free radicals in the brain before the onset of neurological manifestations of central nervous system (CNS) oxygen poisoning. Chronically cannulated, conscious rats were individually placed in a transparent pressure chamber and exposed to (1) 5 atmospheres absolute (ATA) oxygen for 15 min (n = 4); (2) 5 ATA oxygen for 30 min (n = 5), during which no visible convulsions occurred; (3) 5 ATA oxygen for 30 min with recurrent convulsions (n = 6); (4) 5 ATA oxygen until the appearance of the first visible convulsions (n = 5); (5) 4 ATA oxygen for 60 min during which no convulsions occurred (n = 5); and (6) 5 ATA air for 30 min (n = 5, controls). Immediately before compression, 1 mL of 0.1 M of alpha-phenyl-N-tert-butyl nitrone (PBN) was administered intravenously (iv) for spin trapping. At the termination of each experiment, rats were euthanized by pentobarbital iv and decompressed within 1 min. Brains were rapidly removed for preparation of lipid extracts (Folch). The presence of PBN spin adducts in the lipid extracts was examined by electron spin resonance (ESR) spectroscopy. ESR spectra from unconvulsed rats exposed to 5 ATA oxygen for 30 min revealed both oxygen-centered and carbon-centered PBN spin adducts in three of the five brains. One of the five rats in this group showed an ascorbyl signal in the ESR spectrum.(ABSTRACT TRUNCATED AT 250 WORDS)

A spectral study of a radio-frequency plasma-generated flux of atomic oxygen

NASA Technical Reports Server (NTRS)

Batten, Carmen E.; Brown, Kenneth G.; Lewis, Beverley W.

1994-01-01

The active environment of a radio-frequency (RF) plasma generator, with and without low-pressure oxygen, has been characterized through the identification of emission lines in the spectral region from 250 to 900 nm. The environment is shown to be dependent on the partial pressure of oxygen and the power applied to the RF generator. Atomic oxygen has been found in significant amounts as well as atomic hydrogen and the molecular oxygen species O2((sup 1)Sigma). The only charged species observed was the singly charged molecular ion O2(+). With a polymer specimen in the plasma chamber, carbon monoxide was also observed. The significance of these observations with respect to previous studies using this type of generator to stimulate material degradation in space is discussed. The possibility of using these generators as atomic oxygen sources in the development of oxygen atom fluorescence sensors is explored.

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

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

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

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

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

DOEpatents

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

2014-01-07

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

Isoprenoid Alcohols are Susceptible to Oxidation with Singlet Oxygen and Hydroxyl Radicals.

PubMed

Komaszylo Née Siedlecka, Joanna; Kania, Magdalena; Masnyk, Marek; Cmoch, Piotr; Lozinska, Iwona; Czarnocki, Zbigniew; Skorupinska-Tudek, Karolina; Danikiewicz, Witold; Swiezewska, Ewa

2016-02-01

Isoprenoids, as common constituents of all living cells, are exposed to oxidative agents--reactive oxygen species, for example, singlet oxygen or hydroxyl radicals. Despite this fact, products of oxidation of polyisoprenoids have never been characterized. In this study, chemical oxidation of isoprenoid alcohols (Prenol-2 and -10) was performed using singlet oxygen (generated in the presence of hydrogen peroxide/molybdate or upon photochemical reaction in the presence of porphyrin), oxygen (formed upon hydrogen peroxide dismutation) or hydroxyl radical (generated by the hydrogen peroxide/sonication, UV/titanium dioxide or UV/hydrogen peroxide) systems. The structure of the obtained products, hydroxy-, peroxy- and heterocyclic derivatives, was studied with the aid of mass spectrometry (MS) and nuclear magnetic resonance (NMR) methods. Furthermore, mass spectrometry with electrospray ionization appeared to be a useful analytical tool to detect the products of oxidation of isoprenoids (ESI-MS analysis), as well as to establish their structure on the basis of the fragmentation spectra of selected ions (ESI-MS/MS analysis). Taken together, susceptibility of polyisoprenoid alcohols to various oxidizing agents was shown for the first time.

Cellular defense against singlet oxygen-induced oxidative damage by cytosolic NADP+-dependent isocitrate dehydrogenase.

PubMed

Kim, Sun Yee; Park, Jeen-Woo

2003-03-01

Singlet oxygen (1O2) is a highly reactive form of molecular oxygen that may harm living systems by oxidizing critical cellular macromolecules. Recently, we have shown that NADP+-dependent isocitrate dehydrogenase is involved in the supply of NADPH needed for GSH production against cellular oxidative damage. In this study, we investigated the role of cytosolic form of NADP+-dependent isocitrate dehydrogenase (IDPc) against singlet oxygen-induced cytotoxicity by comparing the relative degree of cellular responses in three different NIH3T3 cells with stable transfection with the cDNA for mouse IDPc in sense and antisense orientations, where IDPc activities were 2.3-fold higher and 39% lower, respectively, than that in the parental cells carrying the vector alone. Upon exposure to singlet oxygen generated from photoactivated dye, the cells with low levels of IDPc became more sensitive to cell killing. Lipid peroxidation, protein oxidation, oxidative DNA damage and intracellular peroxide generation were higher in the cell-line expressing the lower level of IDPc. However, the cells with the highly over-expressed IDPc exhibited enhanced resistance against singlet oxygen, compared to the control cells. The data indicate that IDPc plays an important role in cellular defense against singlet oxygen-induced oxidative injury.

Cavity transport effects in generator-collector electrochemical analysis of nitrobenzene.

PubMed

Lewis, Grace E M; Dale, Sara E C; Kasprzyk-Hordern, Barbara; Lubben, Anneke T; Barnes, Edward O; Compton, Richard G; Marken, Frank

2014-09-21

Two types of generator-collector electrode systems, (i) a gold-gold interdigitated microband array and (ii) a gold-gold dual-plate microtrench, are compared for nitrobenzene electroanalysis in aerated aqueous 0.1 M NaOH. The complexity of the nitrobenzene reduction in conjunction with the presence of ambient levels of oxygen in the analysis solution provide a challenging problem in which feedback-amplified generator-collector steady state currents provide the analytical signal. In contrast to the more openly accessible geometry of the interdigitated array electrode, where the voltammetric response for nitrobenzene is less well-defined and signals drift, the voltammetric response for the cavity-like microtrench electrode is stable and readily detectable at 1 μM level. Both types of electrode show oxygen-enhanced low concentration collector current responses due to additional feedback via reaction intermediates. The observations are rationalised in terms of a "cavity transport coefficient" which is beneficial in the dual-plate microtrench, where oxygen interference effects are suppressed and the analytical signal is amplified and stabilised.

Three Years of on Orbit ISS Oxygen Generation System Operation 2007-2010

NASA Technical Reports Server (NTRS)

Diderich, Greg S.; Polis, Pete; VanKeuren, Steven P.; Erickson, Bob

2010-01-01

The International Space Station (ISS) United States Orbital Segment (USOS) Oxygen Generation System (OGS) has accumulated 240 days of continuous operation at varied oxygen production rates within the US Laboratory Module (LAB) since it was first activated in July 2007. OGS relocated from the ISS LAB to Node 3 during 20A Flight (February 2010). The OGS rack delivery was accelerated for on-orbit checkout in the LAB, and it was launched to ISS in July of 2006. During the on-orbit checkout interval within the LAB from July 2007 to October 2008, OGS operational times were limited by the quantity of feedwater in a Payload Water Reservoir (PWR) bag. Longer runtimes are now achievable due to the continuous feedwater availability after ULF2 delivery and activation of the USOS Water Recovery System (WRS) racks. OGS is considered a critical function to maintaining six crew capability. There have been a number of failures which interrupted or threatened to interrupt oxygen production. Filters in the recirculation loop have clogged and have been replaced, Hydrogen sensors have fallen out of specifications, a pump delta pressure sensor failed, a pump failed to start, and the voltage on the cell stack increased out of tolerance. This paper will discuss the operating experience and characteristics of the OGS, as well as operational issues and their resolution.

Oxygen Generator System Mars In-Situ Propellant Production Precursor Flight

NASA Technical Reports Server (NTRS)

Sridhar, K. R.; Gottmann, M.; Baird, R. S.

1999-01-01

The 2001 Lander to Mars will carry the first ever ISRU payload to Mars. This payload, the Mars In-situ Propellant production Precursor (MIP), will demonstrate a variety of technologies that will be required for future ISRU Mars indigenous material processing plant designs. One of those technologies is that of extracting oxygen from the predominantly carbon dioxide atmosphere of Mars, a prerequisite for future sample return and human missions to Mars. The Oxygen Generator Subsystem (OGS) portion of the MIP will demonstrate this and is the focus of this paper. The primary objective of the OGS is to demonstrate the production of oxygen from Mars atmospheric gases. Secondary objectives are to measure the performance and reliability of oxygen generation hardware in actual mission environments over an extended time. Major constraints on the OGS design came from several sources. The Lander provides power to the system from solar power that is harnessed by photovoltaic arrays. This limited OGS to daytime only operations (six to eight hours) and a maximum power of 15W. The reliance on solar power necessitated thermal cycling of the OGS between Mars ambient and OGS operating temperatures. The Lander also limited the total mass of the MIP payload to 7.5 kg with a correspondingly small volume, and the OGS was one of six experiments in the MIP. Mass and volume were to be minimized. Another constraint was cost. Mission funding, as always, was tight. Cost was to be minimized. In short the OGS design had to be low power (<15 Watts), low mass (1 kg), low volume, low cost, and be capable of cyclical operations for an extended stay on Mars. After extensive research, a zirconia based solid oxide electrolyzer design was selected.

Oxygen Generator System Mars In-Situ Propellant Production Precursor Flight

NASA Technical Reports Server (NTRS)

Sridhar, K. R.; Gottmann, M.; Baird, R. S.

1999-01-01

The 2001 Lander to Mars will carry the first ever In situ Resource Utilization (ISRU) payload to Mars. This payload, the Mars In-situ Propellant production Precursor (MIP), will demonstrate a variety of technologies that will be required for future ISRU Mars indigenous material processing plant designs. One of those technologies is that of extracting oxygen from the predominantly carbon dioxide atmosphere of Mars, a prerequisite for future sample return and human missions to Mars. The Oxygen Generator Subsystem (OGS) portion of the MIP will demonstrate this and is the focus of this paper. The primary objective of the OGS is to demonstrate the production of oxygen from Mars atmospheric gases. Secondary objectives are to measure the performance and reliability of oxygen generation hardware in actual mission environments over an extended time. Major constraints on the OGS design came from several sources. The Lander provides power to the system from solar power that is harnessed by photovoltaic arrays. This limited OGS to daytime only operations (six to eight hours) and a maximum power of 15W. The reliance on solar power necessitated thermal cycling of the OGS between Mars ambient and OGS operating temperatures. The Lander also limited the total mass of the MIP payload to 7.5 kg with a correspondingly small volume, and the OGS was one of six experiments in the MIP Mass and volume were to be minimized. Another constraint was cost. Mission funding, as always, was tight. Cost was to be minimized. In short the OGS design had to be low power (<15 Watts), low mass (1 kg), low volume, low cost, and be capable of cyclical operations for an extended stay on Mars. After extensive research, a zirconia based solid oxide electrolyzer design was selected.

Thermospheric Mass Density Specification: Synthesis of Observations and Models

DTIC Science & Technology

2013-10-21

Simulation Experiments (OSSEs) of the column-integrated ratio of atomic oxygen and molecular nitrogen. Note that OSSEs assimilate, for a given...realistic observing system, synthetically generated observational data often sampled from model simulation results, in place of actually observed values...and molecular oxygen mass mixing ratio). Note that in the TIEGCM the molecular nitrogen mass mixing ratio is specified so that the sum of mixing

Design and test status for life support applications of SPE oxygen generation systems. [Solid Polymer Electrolyte

NASA Technical Reports Server (NTRS)

Titterington, W. A.; Erickson, A. C.

1975-01-01

An advanced six-man rated oxygen generation system has been fabricated and tested as part of a NASA/JSC technology development program for a long lived, manned spacecraft life support system. Details of the design and tests results are presented. The system is based on the Solid Polymer Electrolyte (SPE) water electrolysis technology and its nominal operating conditions are 2760 kN/sq m (400 psia) and 355 K (180 F) with an electrolysis module current density capability up to 350 mA/sq cm (326 ASF). The system is centered on a 13-cell SPE water electrolysis module having a single cell active area of 214 sq cm (33 sq in) and it incorporates instrumentation and controls for single pushbutton automatic startup/shutdown, component fault detection and isolation, and self-contained sensors and controls for automatic safe emergency shutdown. The system has been tested in both the orbital cyclic and continuous mode of operation. Various parametric tests have been completed to define the system capability for potential application in spacecraft environmental systems.

International Space Station United States Orbital Segment Oxygen Generation System On-Orbit Operational Experience

NASA Technical Reports Server (NTRS)

Erickson, Robert J.; Howe, John, Jr.; Kulp, Galen W.; VanKeuren, Steven P.

2008-01-01

The International Space Station (ISS) United States Orbital Segment (USOS) Oxygen Generation System (OGS) was originally intended to be installed in ISS Node 3. The OGS rack delivery was accelerated, and it was launched to ISS in July of 2006 and installed in the US Laboratory Module. Various modification kits were installed to provide its interfaces, and the OGS was first activated in July of 2007 for 15 hours, In October of 2007 it was again activated for 76 hours with varied production rates and day/night cycling. Operational time in each instance was limited by the quantity of feedwater in a Payload Water Reservoir (PWR) bag. Feedwater will be provided by PWR bag until the USOS Water Recovery System (WRS) is delivered to SS in fall of 2008. This paper will discuss operating experience and characteristics of the OGS, as well as operational issues and their resolution.

Advanced Techniques in Pulmonary Function Test Analysis Interpretation and Diagnosis

PubMed Central

Gildea, T.J.; Bell, C. William

1980-01-01

The Pulmonary Functions Analysis and Diagnostic System is an advanced clinical processing system developed for use at the Pulmonary Division, Department of Medicine at the University of Nebraska Medical Center. The system generates comparative results and diagnostic impressions for a variety of routine and specialized pulmonary functions test data. Routine evaluation deals with static lung volumes, breathing mechanics, diffusing capacity, and blood gases while specialized tests include lung compliance studies, small airways dysfunction studies and dead space to tidal volume ratios. Output includes tabular results of normal vs. observed values, clinical impressions and commentary and, where indicated, a diagnostic impression. A number of pulmonary physiological and state variables are entered or sampled (A to D) with periodic status reports generated for the test supervisor. Among the various physiological variables sampled are respiratory frequency, minute ventilation, oxygen consumption, carbon dioxide production, and arterial oxygen saturation.

Investigation of singlet oxygen generation in Vit C-Cu2+ -LDL system by chemiluminescence method

NASA Astrophysics Data System (ADS)

Wang, Juan; Xing, Da; Tan, Shici; Tang, Yonghong; He, Yonghong

2002-04-01

In this study, by chemiluminescence method using a Cypridina luciferin analog, 2-methyl-6-(p-methoxyphenyl)-3,7- dihydroimidazo[1,2-a]pyrazin-3-one (MCLA), as a selective and sensitive chemiluminescence probe, singlet oxygen (1O2) formation was observed in the vit C- LDL-Cu2+ reaction system. Another experimental evidence for the generation of 1O2 was the quenching effect of sodium azide (NaN3) on vit C-induced chemiluminescence in the reaction mixture of LDL- Cu2+-MCLA. Analysis based on the experimental results indicated the plausible reaction mechanism is that vit C converts Cu2+ to its reduced state and vit C becomes vit C radical itself, thereby stimulating the formation of peroxyl radicals, and bimolecular reaction of peroxyl radicals results in 1O2 production in the above systems.

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

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

Zagidullin, M V; Nikolaev, V D

2001-06-30

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

Focused RBCC Experiments: Two-Rocket Configuration Experiments and Hydrocarbon/Oxygen Rocket Ejector Experiments

NASA Technical Reports Server (NTRS)

Santoro, Robert J.; Pal, Sibtosh

2003-01-01

This addendum report documents the results of two additional efforts for the Rocket Based Combined Cycle (RBCC) rocket-ejector mode research work carried out at the Penn State Propulsion Engineering Research Center in support of NASA s technology development efforts for enabling 3 d generation Reusable Launch Vehicles (RLV). The tasks reported here build on an earlier NASA MSFC funded research program on rocket ejector investigations. The first task investigated the improvements of a gaseous hydrogen/oxygen twin thruster RBCC rocket ejector system over a single rocket system. The second task investigated the performance of a hydrocarbon (liquid JP-7)/gaseous oxygen single thruster rocket-ejector system. To gain a systematic understanding of the rocket-ejector s internal fluid mechanic/combustion phenomena, experiments were conducted with both direct-connect and sea-level static diffusion and afterburning (DAB) configurations for a range of rocket operating conditions. For all experimental conditions, overall system performance was obtained through global measurements of wall static pressure profiles, heat flux profiles and engine thrust. Detailed mixing and combustion information was obtained through Raman spectroscopy measurements of major species (gaseous oxygen, hydrogen, nitrogen and water vapor) for the gaseous hydrogen/oxygen rocket ejector experiments.

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

PubMed

Asada, Kozi

1999-06-01

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

Photosensitized generation of singlet oxygen in porous silicon studied by simultaneous measurements of luminescence of nanocrystals and oxygen molecules

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

Gongalsky, M. B.; Kharin, A. Yu.; Zagorodskikh, S. A.

2011-07-01

Photosensitization of singlet oxygen generation in porous silicon (PSi) was investigated by simultaneous measurements of the photoluminescence (PL) of silicon nanocrystals (nc-Si) and the infrared emission of the {sup 1}{Delta}-state of oxygen molecules at 1270 nm (0.98 eV) at room temperature. Photodegradation of the nc-Si PL properties was found to correlate with the efficiency of singlet oxygen generation. The quantum efficiency of singlet oxygen generation in PSi was estimated to be about 1%, while the lifetime of singlet oxygen was about fifteen ms. The kinetics of nc-Si PL intensity under cw excitation undergoes a power law dependence with the exponentmore » dependent on the photon energy of luminescence. The experimental results are explained with a model of photodegradation controlled by the diffusion of singlet oxygen molecules in a disordered structure of porous silicon.« less

Microfluidic dissolved oxygen gradient generator biochip as a useful tool in bacterial biofilm studies.

PubMed

Skolimowski, Maciej; Nielsen, Martin Weiss; Emnéus, Jenny; Molin, Søren; Taboryski, Rafael; Sternberg, Claus; Dufva, Martin; Geschke, Oliver

2010-08-21

A microfluidic chip for generation of gradients of dissolved oxygen was designed, fabricated and tested. The novel way of active oxygen depletion through a gas permeable membrane was applied. Numerical simulations for generation of O(2) gradients were correlated with measured oxygen concentrations. The developed microsystem was used to study growth patterns of the bacterium Pseudomonas aeruginosa in medium with different oxygen concentrations. The results showed that attachment of Pseudomonas aeruginosa to the substrate changed with oxygen concentration. This demonstrates that the device can be used for studies requiring controlled oxygen levels and for future studies of microaerobic and anaerobic conditions.

Electrochemical generation of useful chemical species from lunar materials

NASA Technical Reports Server (NTRS)

Sammells, Anthony F.; Semkow, Krystyna W.

1987-01-01

A high temperature electrolytic cell which simultaneously generates oxygen at the anode and liquid alkali metals at the cathode is electrochemically characterized. The electrolytic technology being investigated utilizes the oxygen vacancy conducting solid electrolyte, yttria stabilized zirconia, which effectively separates the oxygen evolving (at La0.89Sr0.10MnO3) and alkali metal (Li, Na) reducing (from a molten salt at either Pt or FeSi2) half cell reactions. In the finally engineered cell liquid alkali metal would be continuously removed from the cathode compartment and used as an effective reductant for the direct thermochemical refining of lunar ores to their metallic state with simultaneous oxidation of the alkali metal to its oxide. The alkali metal oxide would then be reintroduced into the electrolytic cell to complete the overall system cycle.

Electrochemical generation of useful chemical species from lunar materials

NASA Astrophysics Data System (ADS)

Sammells, Anthony F.; Semkow, Krystyna W.

1987-09-01

A high temperature electrolytic cell which simultaneously generates oxygen at the anode and liquid alkali metals at the cathode is electrochemically characterized. The electrolytic technology being investigated utilizes the oxygen vacancy conducting solid electrolyte, yttria stabilized zirconia, which effectively separates the oxygen evolving (at La0.89Sr0.10MnO3) and alkali metal (Li, Na) reducing (from a molten salt at either Pt or FeSi2) half cell reactions. In the finally engineered cell liquid alkali metal would be continuously removed from the cathode compartment and used as an effective reductant for the direct thermochemical refining of lunar ores to their metallic state with simultaneous oxidation of the alkali metal to its oxide. The alkali metal oxide would then be reintroduced into the electrolytic cell to complete the overall system cycle.

Method of and system for producing electrical power

DOEpatents

Carabetta, Ralph A.; Staats, Gary E.; Cutting, John C.

1993-01-01

A method and system for converting the chemical energy of methane to electrical energy. Methane is thermally decomposed to hydrogen and carbon in a decomposing unit at a temperature not less than 1200.degree. K. and at a pressure above atmospheric pressure. Carbon and substantially pure oxygen and a cesium or potassium seed material is transmitted to a combustor which is maintained at a pressure of at least 50 atmospheres to combust the carbon and oxygen and provide an ionized plasma having a temperature not less than 2900.degree. K. The ionized plasma is accelerated to a velocity not less than 1000 m/sec and transported through an MHD generator having a magnetic field in the range of from 4 to 6 Tesla to generate dc power. The ionized plasma is decelerated and passed from the MHD generator in heat exchange relationship with the methane to heat the methane for decomposition, and thereafter any cesium or potassium seed material is recovered and transported to the combustor, and the dc power from the MHD generator is converted to ac power.

Method of and system for producing electrical power

DOEpatents

Carabetta, Ralph A.; Staats, Gary E.; Cutting, John C.

1993-01-01

A method and system for converting the chemical energy of methane to electrical energy. Methane is thermally decomposed to hydrogen and carbon in a decomposing unit at a temperature not less than about 1200.degree. K. and at a pressure at least slightly above atmospheric pressure. Carbon and substantially pure oxygen and a cesium or potassium seed material is transmitted to a combustor which is maintained at a pressure of at least about 50 atmospheres to combust the carbon and oxygen and provide an ionized plasma having a temperature not less than about 2800.degree. K. The ionized plasma is accelerated to a velocity not less than about 1000 m/sec and transported through an MHD generator having a magnetic field in the range of from about 4 to about 6 Tesla to generate dc power. The ionized plasma is de-accelerated and passed from the MHD generator in heat exchange relationship with the methane to heat same for decomposition and or reaction, and thereafter any cesium or potassium seed material is recovered and transported to the combustor, and the dc power from the MHD generator is converted to ac power.

Singlet oxygen generation during the oxidation of L-tyrosine and L-dopa with mushroom tyrosinase

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

Miyaji, Akimitsu; Kohno, Masahiro; Inoue, Yoshihiro

2016-03-18

The generation of singlet oxygen during the oxidation of tyrosine and L-dopa using mushroom tyrosinase in a phosphate buffer (pH 7.4), the model of melanin synthesis in melanocytes, was examined. The reaction was performed in the presence of 2,2,6,6-tetramethyl-4-piperidone (4-oxo-TEMP), an acceptor of singlet oxygen and the electron spin resonance (ESR) of the spin adduct, 4-oxo-2,2,6,6-tetramethyl-1-piperidinyloxy (4-oxo-TEMPO), was measured. An increase in the ESR signal attributable to 4-oxo-TEMPO was observed during the oxidation of tyrosine and L-dopa with tyrosinase, indicating the generation of singlet oxygen. The results suggest that {sup 1}O{sub 2} generation via tyrosinase-catalyzed melanin synthesis occurs in melanocyte.more » - Highlights: • Generation of singlet oxygen was observed during tyrosinase-catalyzed tyrosine oxidation. • The singlet oxygen generated when tyrosine was converted into dopachrome. • The amount of singlet oxygen is not sufficient for cell toxicity. • It decreased when the hydroxyl radicals and/or superoxide anions were trapped.« less

Hydrogen gas alleviates oxygen toxicity by reducing hydroxyl radical levels in PC12 cells.

PubMed

Yu, Junchao; Yu, Qiuhong; Liu, Yaling; Zhang, Ruiyun; Xue, Lianbi

2017-01-01

Hyperbaric oxygen (HBO) therapy through breathing oxygen at the pressure of above 1 atmosphere absolute (ATA) is useful for varieties of clinical conditions, especially hypoxic-ischemic diseases. Because of generation of reactive oxygen species (ROS), breathing oxygen gas at high pressures can cause oxygen toxicity in the central nervous system, leading to multiple neurological dysfunction, which limits the use of HBO therapy. Studies have shown that Hydrogen gas (H2) can diminish oxidative stress and effectively reduce active ROS associated with diseases. However, the effect of H2 on ROS generated from HBO therapy remains unclear. In this study, we investigated the effect of H2 on ROS during HBO therapy using PC12 cells. PC12 cells cultured in medium were exposed to oxygen gas or mixed oxygen gas and H2 at 1 ATA or 5 ATA. Cells viability and oxidation products and ROS were determined. The data showed that H2 promoted the cell viability and inhibited the damage in the cell and mitochondria membrane, reduced the levels of lipid peroxidation and DNA oxidation, and selectively decreased the levels of •OH but not disturbing the levels of O2•-, H2O2, or NO• in PC12 cells during HBO therapy. These results indicated that H2 effectively reduced •OH, protected cells against oxygen toxicity resulting from HBO therapy, and had no effect on other ROS. Our data supported that H2 could be potentially used as an antioxidant during HBO therapy.

Developing a Customized Perfusion Bioreactor Prototype with Controlled Positional Variability in Oxygen Partial Pressure for Bone and Cartilage Tissue Engineering.

PubMed

Lee, Poh Soo; Eckert, Hagen; Hess, Ricarda; Gelinsky, Michael; Rancourt, Derrick; Krawetz, Roman; Cuniberti, Gianaurelio; Scharnweber, Dieter

2017-05-01

Skeletal development is a multistep process that involves the complex interplay of multiple cell types at different stages of development. Besides biochemical and physical cues, oxygen tension also plays a pivotal role in influencing cell fate during skeletal development. At physiological conditions, bone cells generally reside in a relatively oxygenated environment whereas chondrocytes reside in a hypoxic environment. However, it is technically challenging to achieve such defined, yet diverse oxygen distribution on traditional in vitro cultivation platforms. Instead, engineered osteochondral constructs are commonly cultivated in a homogeneous, stable environment. In this study, we describe a customized perfusion bioreactor having stable positional variability in oxygen tension at defined regions. Further, engineered collagen constructs were coaxed into adopting the shape and dimensions of defined cultivation platforms that were precasted in 1.5% agarose bedding. After cultivating murine embryonic stem cells that were embedded in collagen constructs for 50 days, mineralized constructs of specific dimensions and a stable structural integrity were achieved. The end-products, specifically constructs cultivated without chondroitin sulfate A (CSA), showed a significant increase in mechanical stiffness compared with their initial gel-like constructs. More importantly, the localization of osteochondral cell types was specific and corresponded to the oxygen tension gradient generated in the bioreactor. In addition, CSA in complementary with low oxygen tension was also found to be a potent inducer of chondrogenesis in this system. In summary, we have demonstrated a customized perfusion bioreactor prototype that is capable of generating a more dynamic, yet specific cultivation environment that could support propagation of multiple osteochondral lineages within a single engineered construct in vitro. Our system opens up new possibilities for in vitro research on human skeletal development.

Development of a gravity-independent wastewater bioprocessor for advanced life support in space

NASA Technical Reports Server (NTRS)

Nashashibi-Rabah, Majda; Christodoulatos, Christos; Korfiatis, George P.; Janes, H. W. (Principal Investigator)

2005-01-01

Operation of aerobic biological reactors in space is controlled by a number of challenging constraints, mainly stemming from mass transfer limitations and phase separation. Immobilized-cell packed-bed bioreactors, specially designed to function in the absence of gravity, offer a viable solution for the treatment of gray water generated in space stations and spacecrafts. A novel gravity-independent wastewater biological processor, capable of carbon oxidation and nitrification of high-strength aqueous waste streams, is presented. The system, consisting of a fully saturated pressurized packed bed and a membrane oxygenation module attached to an external recirculation loop, operated continuously for over one year. The system attained high carbon oxidation efficiencies often exceeding 90% and ammonia oxidation reaching approximately 60%. The oxygen supply module relies on hydrophobic, nonporous, oxygen selective membranes, in a shell and tube configuration, for transferring oxygen to the packed bed, while keeping the gaseous and liquid phases separated. This reactor configuration and operating mode render the system gravity-independent and suitable for space applications.

Antioxidant effects of herbal therapies used by patients with inflammatory bowel disease: an in vitro study.

PubMed

Langmead, L; Dawson, C; Hawkins, C; Banna, N; Loo, S; Rampton, D S

2002-02-01

Herbal remedies used by patients for treatment of inflammatory bowel disease include slippery elm, fenugreek, devil's claw, Mexican yam, tormentil and wei tong ning, a traditional Chinese medicine. Reactive oxygen metabolites produced by inflamed colonic mucosa may be pathogenic. Aminosalicylates (5-ASA) are antioxidant and other such agents could be therapeutic. To assess the antioxidant effects of herbal remedies in cell-free oxidant-generating systems and inflamed human colorectal biopsies. Luminol-enhanced chemiluminescence in a xanthine/xanthine oxidase cell-free system was used to detect superoxide scavenging by herbs and 5-ASA, and fluorimetry to define peroxyl radical scavenging using a phycoerythrin degradation assay. Chemiluminescence was used to detect herbal effects on generation of oxygen radicals by mucosal biopsies from patients with active ulcerative colitis. Like 5-ASA, all herbs, except fenugreek, scavenged superoxide dose-dependently. All materials tested scavenged peroxyl dose-dependently. Oxygen radical release from biopsies was reduced after incubation in all herbs except Mexican yam, and by 5-ASA. All six herbal remedies have antioxidant effects. Fenugreek is not a superoxide scavenger, while Mexican yam did not inhibit radical generation by inflamed biopsies. Slippery elm, fenugreek, devil's claw, tormentil and wei tong ning merit formal evaluation as novel therapies in inflammatory bowel disease.

Oxygen Supplementation to Stabilize Preterm Infants in the Fetal to Neonatal Transition: No Satisfactory Answer.

PubMed

Torres-Cuevas, Isabel; Cernada, Maria; Nuñez, Antonio; Escobar, Javier; Kuligowski, Julia; Chafer-Pericas, Consuelo; Vento, Maximo

2016-01-01

Fetal life elapses in a relatively low oxygen environment. Immediately after birth with the initiation of breathing, the lung expands and oxygen availability to tissue rises by twofold, generating a physiologic oxidative stress. However, both lung anatomy and function and the antioxidant defense system do not mature until late in gestation, and therefore, very preterm infants often need respiratory support and oxygen supplementation in the delivery room to achieve postnatal stabilization. Notably, interventions in the first minutes of life can have long-lasting consequences. Recent trials have aimed to assess what initial inspiratory fraction of oxygen and what oxygen targets during this transitional period are best for extremely preterm infants based on the available nomogram. However, oxygen saturation nomogram informs only of term and late preterm infants but not on extremely preterm infants. Therefore, the solution to this conundrum may still have to wait before a satisfactory answer is available.

Increased Oxygen Recovery from Sabatier Systems Using Plasma Pyrolysis Technology and Metal Hydride Separation

NASA Technical Reports Server (NTRS)

Greenwood, Zachary W.; Abney, Morgan B.; Perry, Jay L.; Miller, Lee A.; Dahl, Roger W.; Hadley, Neal M.; Wambolt, Spencer R.; Wheeler, Richard R.

2015-01-01

State-of-the-art life support carbon dioxide (CO2) reduction technology is based on the Sabatier reaction where less than 50% of the oxygen required for the crew is recovered from metabolic CO2. The reaction produces water as the primary product and methane as a byproduct. Oxygen recovery is constrained by the limited availability of reactant hydrogen. This is further exacerbated when Sabatier methane (CH4) is vented as a waste product resulting in a continuous loss of reactant hydrogen. Post-processing methane with the Plasma Pyrolysis Assembly (PPA) to recover hydrogen has the potential to dramatically increase oxygen recovery and thus drastically reduce the logistical challenges associated with oxygen resupply. The PPA decomposes methane into predominantly hydrogen and acetylene. Due to the highly unstable nature of acetylene, a separation system is necessary to purify hydrogen before it is recycled back to the Sabatier reactor. Testing and evaluation of a full-scale Third Generation PPA is reported and investigations into metal hydride hydrogen separation technology is discussed.

Toxin detection using a tyrosinase-coupled oxygen electrode.

PubMed

Smit, M H; Rechnitz, G A

1993-02-15

An enzyme-based "electrochemical canary" is described for the detection of cyanide. The sensing system imitates cyanide's site of toxicity in the mitochondria. The terminal sequence of electron transfer in aerobic respiration is mimicked by mediator coupling of tyrosinase catalysis to an electro-chemical system. An enzyme-coupled oxygen electrode is created which is sensitive to selective poisoning. Biocatalytic reduction of oxygen is promoted by electrochemically supplying tyrosinase with electrons. Thus, ferrocyanide is generated at a cathode and mediates the enzymatic reduction of oxygen to water. An enzyme-dependent reductive current can be monitored which is inhibited by cyanide in a concentration-dependent manner. Oxygen depletion in the reaction layer can be minimized by addressing enzyme activity using a potential pulsing routine. Enzyme activity is electrochemically initiated and terminated and the sensor becomes capable of continuous monitoring. Cyanide poisoning of the biological component is reversible, and it can be reused after rinsing. The resulting sensor detects cyanide based on its biological activity rather than its physical or chemical properties.

The electrochemical generation of useful chemical species from lunar materials

NASA Technical Reports Server (NTRS)

Tsai, Kan J.; Kuchynka, Daniel J.; Sammells, Anthony F.

1989-01-01

The current status of work on an electrochemical technology for the simultaneous generation of oxygen and lithium from a Li2O containing molten salt (Li2O-LiCl-LiF) is discussed. The electrochemical cell utilizes an oxygen vacancy conducting solid electrolyte, yttria-stabilized zirconia, to effect separation between the oxygen evolving and lithium reduction half-cell reactions. The cell, which operates at 700 to 800 C, possesses rapid electrode kinetics at the lithium-alloy electrode with exchange current density values being greater than 60 mA/sq cm, showing high reversibility for this reaction. When used in the electrolytic mode, lithium produced at the negative electrode would be continuously removed from the cell for later use (under lunar conditions) as an easily storable reducting agent (compared to H2) for the chemical refining of lunar ores via the general reaction: 2Li + MO yields Li2O + M where MO represents a lunar ore. Emphasis to this time has been on the simulated lunar ore ilmenite (FeTiO3), which we have found becomes chemically reduced by Li at 432 C. Furthermore, both Fe2O3 and TiO2 have been reduced by Li to give the corresponding metal. This electrochemical approach provides a convenient route for producing metals under lunar conditions and oxygen for the continuous maintenance of human habitats on the Moon's surface. Because of the high reversibility of this electrochemical system, it has also formed the basis for the lithium-oxygen secondary battery. This secondary lithium-oxygen battery system posses the highest theoretical energy density yet investigated.

The electrochemical generation of useful chemical species from lunar materials

NASA Astrophysics Data System (ADS)

Tsai, Kan J.; Kuchynka, Daniel J.; Sammells, Anthony F.

1989-03-01

The current status of work on an electrochemical technology for the simultaneous generation of oxygen and lithium from a Li2O containing molten salt (Li2O-LiCl-LiF) is discussed. The electrochemical cell utilizes an oxygen vacancy conducting solid electrolyte, yttria-stabilized zirconia, to effect separation between the oxygen evolving and lithium reduction half-cell reactions. The cell, which operates at 700 to 800 C, possesses rapid electrode kinetics at the lithium-alloy electrode with exchange current density values being greater than 60 mA/sq cm, showing high reversibility for this reaction. When used in the electrolytic mode, lithium produced at the negative electrode would be continuously removed from the cell for later use (under lunar conditions) as an easily storable reducting agent (compared to H2) for the chemical refining of lunar ores via the general reaction: 2Li + MO yields Li2O + M where MO represents a lunar ore. Emphasis to this time has been on the simulated lunar ore ilmenite (FeTiO3), which we have found becomes chemically reduced by Li at 432 C. Furthermore, both Fe2O3 and TiO2 have been reduced by Li to give the corresponding metal. This electrochemical approach provides a convenient route for producing metals under lunar conditions and oxygen for the continuous maintenance of human habitats on the Moon's surface. Because of the high reversibility of this electrochemical system, it has also formed the basis for the lithium-oxygen secondary battery. This secondary lithium-oxygen battery system posses the highest theoretical energy density yet investigated.

Reactive oxygen species, essential molecules, during plant-pathogen interactions.

PubMed

Camejo, Daymi; Guzmán-Cedeño, Ángel; Moreno, Alexander

2016-06-01

Reactive oxygen species (ROS) are continually generated as a consequence of the normal metabolism in aerobic organisms. Accumulation and release of ROS into cell take place in response to a wide variety of adverse environmental conditions including salt, temperature, cold stresses and pathogen attack, among others. In plants, peroxidases class III, NADPH oxidase (NOX) locates in cell wall and plasma membrane, respectively, may be mainly enzymatic systems involving ROS generation. It is well documented that ROS play a dual role into cells, acting as important signal transduction molecules and as toxic molecules with strong oxidant power, however some aspects related to its function during plant-pathogen interactions remain unclear. This review focuses on the principal enzymatic systems involving ROS generation addressing the role of ROS as signal molecules during plant-pathogen interactions. We described how the chloroplasts, mitochondria and peroxisomes perceive the external stimuli as pathogen invasion, and trigger resistance response using ROS as signal molecule. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Space station propulsion test bed

NASA Technical Reports Server (NTRS)

Briley, G. L.; Evans, S. A.

1989-01-01

A test bed was fabricated to demonstrate hydrogen/oxygen propulsion technology readiness for the intital operating configuration (IOC) space station application. The test bed propulsion module and computer control system were delivered in December 1985, but activation was delayed until mid-1986 while the propulsion system baseline for the station was reexamined. A new baseline was selected with hydrogen/oxygen thruster modules supplied with gas produced by electrolysis of waste water from the space shuttle and space station. As a result, an electrolysis module was designed, fabricated, and added to the test bed to provide an end-to-end simulation of the baseline system. Subsequent testing of the test bed propulsion and electrolysis modules provided an end-to-end demonstration of the complete space station propulsion system, including thruster hot firings using the oxygen and hydrogen generated from electrolysis of water. Complete autonomous control and operation of all test bed components by the microprocessor control system designed and delivered during the program was demonstrated. The technical readiness of the system is now firmly established.

Singlet oxygen treatment of tumor cells triggers extracellular singlet oxygen generation, catalase inactivation and reactivation of intercellular apoptosis-inducing signaling☆

PubMed Central

Riethmüller, Michaela; Burger, Nils; Bauer, Georg

2015-01-01

Intracellular singlet oxygen generation in photofrin-loaded cells caused cell death without discrimination between nonmalignant and malignant cells. In contrast, extracellular singlet oxygen generation caused apoptosis induction selectively in tumor cells through singlet oxygen-mediated inactivation of tumor cell protective catalase and subsequent reactivation of intercellular ROS-mediated apoptosis signaling through the HOCl and the NO/peroxynitrite signaling pathway. Singlet oxygen generation by extracellular photofrin alone was, however, not sufficient for optimal direct inactivation of catalase, but needed to trigger the generation of cell-derived extracellular singlet oxygen through the interaction between H2O2 and peroxynitrite. Thereby, formation of peroxynitrous acid, generation of hydroxyl radicals and formation of perhydroxyl radicals (HO2.) through hydroxyl radical/H2O2 interaction seemed to be required as intermediate steps. This amplificatory mechanism led to the formation of singlet oxygen at a sufficiently high concentration for optimal inactivation of membrane-associated catalase. At low initial concentrations of singlet oxygen, an additional amplification step needed to be activated. It depended on singlet oxygen-dependent activation of the FAS receptor and caspase-8, followed by caspase-8-mediated enhancement of NOX activity. The biochemical mechanisms described here might be considered as promising principle for the development of novel approaches in tumor therapy that specifically direct membrane-associated catalase of tumor cells and thus utilize tumor cell-specific apoptosis-inducing ROS signaling. PMID:26225731

Singlet oxygen treatment of tumor cells triggers extracellular singlet oxygen generation, catalase inactivation and reactivation of intercellular apoptosis-inducing signaling.

PubMed

Riethmüller, Michaela; Burger, Nils; Bauer, Georg

2015-12-01

Intracellular singlet oxygen generation in photofrin-loaded cells caused cell death without discrimination between nonmalignant and malignant cells. In contrast, extracellular singlet oxygen generation caused apoptosis induction selectively in tumor cells through singlet oxygen-mediated inactivation of tumor cell protective catalase and subsequent reactivation of intercellular ROS-mediated apoptosis signaling through the HOCl and the NO/peroxynitrite signaling pathway. Singlet oxygen generation by extracellular photofrin alone was, however, not sufficient for optimal direct inactivation of catalase, but needed to trigger the generation of cell-derived extracellular singlet oxygen through the interaction between H2O2 and peroxynitrite. Thereby, formation of peroxynitrous acid, generation of hydroxyl radicals and formation of perhydroxyl radicals (HO2(.)) through hydroxyl radical/H2O2 interaction seemed to be required as intermediate steps. This amplificatory mechanism led to the formation of singlet oxygen at a sufficiently high concentration for optimal inactivation of membrane-associated catalase. At low initial concentrations of singlet oxygen, an additional amplification step needed to be activated. It depended on singlet oxygen-dependent activation of the FAS receptor and caspase-8, followed by caspase-8-mediated enhancement of NOX activity. The biochemical mechanisms described here might be considered as promising principle for the development of novel approaches in tumor therapy that specifically direct membrane-associated catalase of tumor cells and thus utilize tumor cell-specific apoptosis-inducing ROS signaling. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Integrated photoelectrochemical cell and system having a liquid electrolyte

DOEpatents

Deng, Xunming; Xu, Liwei

2010-07-06

An integrated photoelectrochemical (PEC) cell generates hydrogen and oxygen from water while being illuminated with radiation. The PEC cell employs a liquid electrolyte, a multi-junction photovoltaic electrode, and a thin ion-exchange membrane. A PEC system and a method of making such PEC cell and PEC system are also disclosed.

Oxygen sensation and social feeding mediated by a C. elegans guanylate cyclase homologue.

PubMed

Gray, Jesse M; Karow, David S; Lu, Hang; Chang, Andy J; Chang, Jennifer S; Ellis, Ronald E; Marletta, Michael A; Bargmann, Cornelia I

2004-07-15

Specialized oxygen-sensing cells in the nervous system generate rapid behavioural responses to oxygen. We show here that the nematode Caenorhabditis elegans exhibits a strong behavioural preference for 5-12% oxygen, avoiding higher and lower oxygen levels. 3',5'-cyclic guanosine monophosphate (cGMP) is a common second messenger in sensory transduction and is implicated in oxygen sensation. Avoidance of high oxygen levels by C. elegans requires the sensory cGMP-gated channel tax-2/tax-4 and a specific soluble guanylate cyclase homologue, gcy-35. The GCY-35 haem domain binds molecular oxygen, unlike the haem domains of classical nitric-oxide-regulated guanylate cyclases. GCY-35 and TAX-4 mediate oxygen sensation in four sensory neurons that control a naturally polymorphic social feeding behaviour in C. elegans. Social feeding and related behaviours occur only when oxygen exceeds C. elegans' preferred level, and require gcy-35 activity. Our results suggest that GCY-35 is regulated by molecular oxygen, and that social feeding can be a behavioural strategy for responding to hyperoxic environments.

Tissue oxygen monitoring by photoacoustic lifetime imaging (PALI) and its application to image-guided photodynamic therapy (PDT)

NASA Astrophysics Data System (ADS)

Shao, Qi; Morgounova, Ekaterina; Ashkenazi, Shai

2015-03-01

The oxygen partial pressure (pO2), which results from the balance between oxygen delivery and its consumption, is a key component of the physiological state of a tissue. Images of oxygen distribution can provide essential information for identifying hypoxic tissue and optimizing cancer treatment. Previously, we have reported a noninvasive in vivo imaging modality based on photoacoustic lifetime. The technique maps the excited triplet state of oxygen-sensitive dye, thus reflects the spatial and temporal distribution of tissue oxygen. We have applied PALI on tumor on small animals to identify hypoxia area. We also showed that PALI is able monitor changes of tissue oxygen, in an acute ischemia and breathing modulation model. Here we present our work on developing a treatment/imaging modality (PDT-PALI) that integrates PDT and a combined ultrasound/photoacoustic imaging system. The system provides real-time feedback of three essential parameters namely: tissue oxygen, light penetration in tumor location, and distribution of photosensitizer. Tissue oxygen imaging is performed by applying PALI, which relies on photoacoustic probing of oxygen-dependent, excitation lifetime of Methylene Blue (MB) photosensitizer. Lifetime information can also be used to generate image showing the distribution of photosensitizer. The level and penetration depth of PDT illumination can be deduced from photoacoustic imaging at the same wavelength. All images will be combined with ultrasound B-mode images for anatomical reference.

A kinetic study of the interaction between atomic oxygen and aerosols

NASA Technical Reports Server (NTRS)

Akers, F. I.; Wightman, J. P.

1976-01-01

This study was concerned with the effects of NH4Cl and (NH4)2SO4 aerosols on the kinetics of disappearance of atomic oxygen. Atomic oxygen was generated by a 2.45-GHz microwave discharge and the kinetics of disappearance measured in a fast flow system using NO2 titration. Values of the recombination coefficient for heterogeneous wall recombination were determined for clean, H2SO4-coated, and (NH4)2SO4-coated Pyrex to be 0.000050, 0.000020, and 0.000019, respectively. A rapid exothermic chemical reaction was found to occur between atomic oxygen and an NH4Cl wall coating; the products were NH3, NO, H2O, and HCl. The NH4Cl aerosol was generated by gas phase reaction of NH3 with HCl. The aerosol particles were approximately spherical and nearly monodisperse with a mean diameter of 1.6 plus or minus 0.2 micron. The rate constant for the disappearance of atomic oxygen in the presence of NH4Cl aerosol was measured. No significant decrease was observed in the rate of disappearance of atomic oxygen in the presence of an (NH4)2SO4 aerosol at a concentration of 285 mg per cu m.

Efficient Active Oxygen Free Radical Generated in Tumor Cell by Loading-(HCONH2)·H2O2 Delivery Nanosystem with Soft-X-ray Radiotherapy

PubMed Central

Xu, Lei; Shao, Yiran; Chang, Chengkang; Zhu, Yingchun

2018-01-01

Tumor hypoxia is known to result in radiotherapy resistance and traditional radiotherapy using super-hard X-ray irradiation can cause considerable damage to normal tissue. Therefore, formamide peroxide (FPO) with high reactive oxygen content was employed to enhance the oxygen concentration in tumor cells and increase the radio-sensitivity of low-energy soft-X-ray. To improve stability of FPO, FPO is encapsulated into polyacrylic acid (PAA)-coated hollow mesoporous silica nanoparticles (FPO@HMSNs-PAA). On account of the pH-responsiveness of PAA, FPO@HMSNs-PAA will release more FPO in simulated acidic tumor microenvironment (pH 6.50) and subcellular endosomes (pH 5.0) than in simulated normal tissue media (pH 7.40). When exposed to soft-X-ray irradiation, the released FPO decomposes into oxygen and the generated oxygen further formed many reactive oxygen species (ROS), leading to significant tumor cell death. The ROS-mediated cytotoxicity of FPO@HMSNs-PAA was confirmed by ROS-induced green fluorescence in tumor cells. The presented FPO delivery system with soft-X-ray irradiation paves a way for developing the next opportunities of radiotherapy toward efficient tumor prognosis. PMID:29649155

Module for Oxygenating Water without Generating Bubbles

NASA Technical Reports Server (NTRS)

Gonzalez-Martin, Anuncia; Sidik, Reyimjan; Kim, Jinseong

2004-01-01

A module that dissolves oxygen in water at concentrations approaching saturation, without generating bubbles of oxygen gas, has been developed as a prototype of improved oxygenators for water-disinfection and water-purification systems that utilize photocatalyzed redox reactions. Depending on the specific nature of a water-treatment system, it is desirable to prevent the formation of bubbles for one or more reasons: (1) Bubbles can remove some organic contaminants from the liquid phase to the gas phase, thereby introducing a gas-treatment problem that complicates the overall water-treatment problem; and/or (2) in some systems (e.g., those that must function in microgravity or in any orientation in normal Earth gravity), bubbles can interfere with the flow of the liquid phase. The present oxygenation module (see Figure 1) is a modified version of a commercial module that contains >100 hollow polypropylene fibers with a nominal pore size of 0.05 m and a total surface area of 0.5 m2. The module was originally designed for oxygenation in a bioreactor, with no water flowing around or inside the tubes. The modification, made to enable the use of the module to oxygenate flowing water, consisted mainly in the encapsulation of the fibers in a tube of Tygon polyvinyl chloride (PVC) with an inside diameter of 1 in. (approx.=25 mm). In operation, water is pumped along the insides of the hollow fibers and oxygen gas is supplied to the space outside the hollow tubes inside the PVC tube. In tests, the pressure drops of water and oxygen in the module were found to be close to zero at water-flow rates ranging up to 320 mL/min and oxygen-flow rates up to 27 mL/min. Under all test conditions, no bubbles were observed at the water outlet. In some tests, flow rates were chosen to obtain dissolved-oxygen concentrations between 25 and 31 parts per million (ppm) . approaching the saturation level of approx.=35 ppm at a temperature of 20 C and pressure of 1 atm (approx.=0.1 MPa). As one would expect, it was observed that the time needed to bring a flow of water from an initial low dissolved-oxygen concentration (e.g., 5 ppm) to a steady high dissolved-oxygen concentration at or near the saturation level depends on the rates of flow of both oxygen and water, among other things. Figure 2 shows the results of an experiment in which a greater flow of oxygen was used during the first few tens of minutes to bring the concentration up to approx.=25 ppm, then a lesser flow was used to maintain the concentration.

Thermodynamic model of Mars Oxygen ISRU Experiment (MOXIE)

NASA Astrophysics Data System (ADS)

Meyen, Forrest E.; Hecht, Michael H.; Hoffman, Jeffrey A.; MOXIE Team

2016-12-01

As humankind expands its footprint in the solar system, it is increasingly important to make use of the resources already in our solar system to make these missions economically feasible and sustainable. In-Situ Resource Utilization (ISRU), the science of using resources at a destination to support exploration missions, unlocks potential destinations by significantly reducing the amount of resources that need to be launched from Earth. Carbon dioxide is an example of an in-situ resource that comprises 96% of the Martian atmosphere and can be used as a source of oxygen for propellant and life support systems. The Mars Oxygen ISRU Experiment (MOXIE) is a payload being developed for NASA's upcoming Mars 2020 rover. MOXIE will produce oxygen from the Martian atmosphere using solid oxide electrolysis (SOXE). MOXIE is on the order of magnitude of a 1% scale model of an oxygen processing plant that might enable a human expedition to Mars in the 2030s through the production of the oxygen needed for the propellant of a Mars ascent vehicle. MOXIE is essentially an energy conversion system that draws energy from the Mars 2020 rover's radioisotope thermoelectric generator and ultimately converts it to stored energy in oxygen and carbon monoxide molecules. A thermodynamic model of this novel system is used to understand this process in order to derive operating parameters for the experiment. This paper specifically describes the model of the SOXE component. Assumptions and idealizations are addressed, including 1D and 2D simplifications. Operating points are discussed as well as impacts of flow rates and production.

77 FR 49386 - Airworthiness Directives; Airbus Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-16

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

Reclaimed wastewater quality enhancement by oxygen injection during transportation.

PubMed

Rodríguez-Gómez, L E; Alvarez, M; Rodríguez-Sevilla, J; Marrero, M C; Hernández, A

2011-01-01

In-sewer treatments have been studied in sewer systems, but few have been carried out on reclaimed wastewater systems. A study of oxygen injection has been performed in a completely filled gravity pipe, 0.6 m in diameter and 62 km long, in cast iron with concrete inside coating, which is part of the reclaimed wastewater reuse scheme of Tenerife (Spain). A high pressure oxygen injection system was installed at 16.0 km from pipe inlet and a constant dosage of 30 mg/L O(2) has been injected during six months, under three different operational modes (low COD, 63 mg/L; high COD, 91 mg/L; and partially nitrified water). Oxygen has been consumed in nitrification and organic matter reduction. Generally, nitrification is clearly favored instead of the organic matter oxidation. Nitrification occurs, in general, with nitrite accumulation due to the presence of free ammonia above 1 mg/L. Denitrification is in all cases incomplete due to a limitation of easily biodegradable organic matter content, inhibiting the appearance of anaerobic conditions and sulfide generation. A notable reduction of organic matter parameters is achieved (TSS below 10 mg/L), which is significantly higher than that observed under the ordinary transport conditions without oxygen. This leads to a final cost reduction, and the oxygen injection system helps water reuse managers to maintain a final good water quality in the case of a treatment plant malfunction.

Capillary-tube-based oxygen/argon micro-plasma system for the inactivation of bacteria suspended in aqueous solution.

PubMed

Weng, Chih-Chiang; Liao, Juinn-Der; Chen, Hsin-Hung; Lin, Tung-Yi; Huang, Chih-Ling

2011-09-01

An aqueous solution containing Escherichia coli can be completely inactivated within a short treatment time using a capillary-tube-based oxygen/argon micro-plasma source. A capillary-tube-based oxygen/argon micro-plasma system with a hollow inner electrode was ignited by a 13.56 MHz radio frequency power supply with a matching network and characterised by optical emission spectroscopy. An aqueous solution containing E. coli was then treated at various the working distances, plasma exposure durations, and oxygen ratios in argon micro-plasma. The treated bacteria were then assessed and qualitatively investigated. The morphologies of treated bacteria were examined using a scanning electron microscope (SEM). In the proposed oxygen/argon micro-plasma system, the intensities of the main emission lines of the excited species, nitric oxide (NO), hydrated oxide (OH), argon (Ar), and atomic oxygen (O), fluctuated with the addition of oxygen to argon micro-plasma. Under a steady state of micro-plasma generation, the complete inactivation of E. coli in aqueous solution was achieved within 90 s of argon micro-plasma exposure time with a working distance of 3 mm. SEM micrographs reveal obvious morphological damage to the treated E. coli. The addition of oxygen to argon micro-plasma increased the variety of O-containing excited species. At a given supply power, the relative intensities of the excited species, NO and OH, correlated with the ultraviolet (UV) intensity, decreased. For the proposed capillary-tube-based micro-plasma system with a hollow inner electrode, the oxygen/argon micro-plasma source is efficient in inactivating E. coli in aqueous solution. The treatment time required for the inactivation process decreases with decreasing working distance or the increasing synthesised effect of reactive species and UV intensity.

Laser controlled singlet oxygen generation in mitochondria to promote mitochondrial DNA replication in vitro.

PubMed

Zhou, Xin; Wang, Yupei; Si, Jing; Zhou, Rong; Gan, Lu; Di, Cuixia; Xie, Yi; Zhang, Hong

2015-11-18

Reports have shown that a certain level of reactive oxygen species (ROS) can promote mitochondrial DNA (mtDNA) replication. However, it is unclear whether it is the mitochondrial ROS that stimulate mtDNA replication and this requires further investigation. Here we employed a photodynamic system to achieve controlled mitochondrial singlet oxygen ((1)O2) generation. HeLa cells incubated with 5-aminolevulinic acid (ALA) were exposed to laser irradiation to induce (1)O2 generation within mitochondria. Increased mtDNA copy number was detected after low doses of 630 nm laser light in ALA-treated cells. The stimulated mtDNA replication was directly linked to mitochondrial (1)O2 generation, as verified using specific ROS scavengers. The stimulated mtDNA replication was regulated by mitochondrial transcription factor A (TFAM) and mtDNA polymerase γ. MtDNA control region modifications were induced by (1)O2 generation in mitochondria. A marked increase in 8-Oxoguanine (8-oxoG) level was detected in ALA-treated cells after irradiation. HeLa cell growth stimulation and G1-S cell cycle transition were also observed after laser irradiation in ALA-treated cells. These cellular responses could be due to a second wave of ROS generation detected in mitochondria. In summary, we describe a controllable method of inducing mtDNA replication in vitro.

STS-84 oxygen generator for Mir on display at SPACEHAB

NASA Technical Reports Server (NTRS)

1997-01-01

An oxygen generator destined to replace a malfunctioning unit on the Russian Mir Space Station is the object of much curiosity during preflight preparations in the SPACEHAB Payload Processing Facility. A SPACEHAB Double Module on the Space Shuttle Atlantis will carry the oxygen generator to Mir during STS-84, the sixth Shuttle-Mir docking. The nearly 300-pound generator, manufactured by RSC Energia in Russia, will replace one of two Mir units that have been malfunctioning recently. The generator functions by electrolysis, which separates water into its oxygen and hydrogen components. The hydrogen is vented and the oxygen is used for breathing by the Mir crew. The generator is 4.2 feet in length and 1.4 feet in diameter. STS-84, which is planned to include a Mir crew exchange of astronaut C. Michael Foale for Jerry M. Linenger, is targeted for a May 15 liftoff.

STS-84 oxygen generator for Mir installation

NASA Technical Reports Server (NTRS)

1997-01-01

In the SPACEHAB Payload Processing Facility, McDonnell Douglas- SPACEHAB technicians prepare a Russian-made oxygen generator for flight in a SPACEHAB Double Module. The oxygen generator, manufactured in Russia by RSC Energia, will be carried aboard the Space Shuttle Atlantis on Mission STS-84 for the Shuttles scheduled docking with the Russian Space Station Mir next month. The nearly 300-pound generator will replace one of two Mir units that have been malfunctioning recently. The generator functions by electrolysis, which separates water into its oxygen and hydrogen components. The hydrogen is vented and the oxygen is used for breathing by the Mir crew. The generator is 4.2 feet in length and 1.4 feet in diameter. STS-84, which is planned to include a Mir crew exchange of astronaut C. Michael Foale for Jerry M. Linenger, is targeted for a May 15 liftoff. It will be the sixth Shuttle-Mir docking.

STS-84 oxygen generator for Mir installation

NASA Technical Reports Server (NTRS)

1997-01-01

McDonnell Douglas-SPACEHAB technicians oversee the move of a Russian-made oxygen generator to a SPACEHAB Double Module, at rear, in the SPACEHAB Payload Processing Facility. In foreground, from left, are Marc Tuttle, Dan Porter and Mike Vawter. The oxygen generator, manufactured in Russia by RSC Energia, will be carried aboard the Space Shuttle Atlantis on Mission STS-84 for the Shuttles scheduled docking with the Russian Space Station Mir next month. The nearly 300-pound generator will replace one of two Mir units that have been malfunctioning recently. The generator functions by electrolysis, which separates water into its oxygen and hydrogen components. The hydrogen is vented and the oxygen is used for breathing by the Mir crew. The generator is 4.2 feet in length and 1.4 feet in diameter. STS-84, which is planned to include a Mir crew exchange of astronaut C. Michael Foale for Jerry M. Linenger, is targeted for a May 15 liftoff.

Oxygen Partial Pressure Is a Rate-Limiting Parameter for Cell Proliferation in 3D Spheroids Grown in Physioxic Culture Condition.

PubMed

Gomes, Aurélie; Guillaume, Ludivine; Grimes, David Robert; Fehrenbach, Jérôme; Lobjois, Valérie; Ducommun, Bernard

2016-01-01

The in situ oxygen partial pressure in normal and tumor tissues is in the range of a few percent. Therefore, when studying cell growth in 3D culture systems, it is essential to consider how the physiological oxygen concentration, rather than the one in the ambient air, influences the proliferation parameters. Here, we investigated the effect of reducing oxygen partial pressure from 21% to 5% on cell proliferation rate and regionalization in a 3D tumor spheroid model. We found that 5% oxygen concentration strongly inhibited spheroid growth, changed the proliferation gradient and reduced the 50% In Depth Proliferation index (IDP50), compared with culture at 21% oxygen. We then modeled the oxygen partial pressure profiles using the experimental data generated by culturing spheroids in physioxic and normoxic conditions. Although hypoxia occurred at similar depth in spheroids grown in the two conditions, oxygen partial pressure was a major rate-limiting factor with a critical effect on cell proliferation rate and regionalization only in spheroids grown in physioxic condition and not in spheroids grown at atmospheric normoxia. Our findings strengthen the need to consider conducting experiment in physioxic conditions (i.e., tissue normoxia) for proper understanding of cancer cell biology and the evaluation of anticancer drugs in 3D culture systems.

Oxygen-boosted immunogenic photodynamic therapy with gold nanocages@manganese dioxide to inhibit tumor growth and metastases.

PubMed

Liang, Ruijing; Liu, Lanlan; He, Huamei; Chen, Zhikuan; Han, Zhiqun; Luo, Zhenyu; Wu, Zhihao; Zheng, Mingbin; Ma, Yifan; Cai, Lintao

2018-09-01

Metastatic triple-negative breast cancer (mTNBC) is an aggressive disease among women worldwide, characterized by high mortality and poor prognosis despite systemic therapy with radiation and chemotherapies. Photodynamic therapy (PDT) is an important strategy to eliminate the primary tumor, however its therapeutic efficacy against metastases and recurrence is still limited. Here, we employed a template method to develop the core-shell gold nanocage@manganese dioxide (AuNC@MnO 2 , AM) nanoparticles as tumor microenvironment responsive oxygen producers and near-infrared (NIR)-triggered reactive oxygen species (ROS) generators for oxygen-boosted immunogenic PDT against mTNBC. In this platform, MnO 2 shell degrades in acidic tumor microenvironment pH/H 2 O 2 conditions and generates massive oxygen to boost PDT effect of AM nanoparticles under laser irradiation. Fluorescence (FL)/photoacoustic (PA)/magnetic resonance (MR) multimodal imaging confirms the effective accumulation of AM nanoparticles with sufficient oxygenation in tumor site to ameliorate local hypoxia. Moreover, the oxygen-boosted PDT effect of AM not only destroys primary tumor effectively but also elicits immunogenic cell death (ICD) with damage-associated molecular patterns (DAMPs) release, which subsequently induces DC maturation and effector cells activation, thereby robustly evoking systematic antitumor immune responses against mTNBC. Hence, this oxygen-boosted immunogenic PDT nanosystem offers a promising approach to ablate primary tumor and simultaneously prevent tumor metastases via immunogenic abscopal effects. Copyright © 2018 Elsevier Ltd. All rights reserved.

Method of Separating Oxygen From Spacecraft Cabin Air to Enable Extravehicular Activities

NASA Technical Reports Server (NTRS)

Graf, John C.

2013-01-01

Extravehicular activities (EVAs) require high-pressure, high-purity oxygen. Shuttle EVAs use oxygen that is stored and transported as a cryogenic fluid. EVAs on the International Space Station (ISS) presently use the Shuttle cryo O2, which is transported to the ISS using a transfer hose. The fluid is compressed to elevated pressures and stored as a high-pressure gas. With the retirement of the shuttle, NASA has been searching for ways to deliver oxygen to fill the highpressure oxygen tanks on the ISS. A method was developed using low-pressure oxygen generated onboard the ISS and released into ISS cabin air, filtering the oxygen from ISS cabin air using a pressure swing absorber to generate a low-pressure (high-purity) oxygen stream, compressing the oxygen with a mechanical compressor, and transferring the high-pressure, high-purity oxygen to ISS storage tanks. The pressure swing absorber (PSA) can be either a two-stage device, or a single-stage device, depending on the type of sorbent used. The key is to produce a stream with oxygen purity greater than 99.5 percent. The separator can be a PSA device, or a VPSA device (that uses both vacuum and pressure for the gas separation). The compressor is a multi-stage mechanical compressor. If the gas flow rates are on the order of 5 to 10 lb (.2.3 to 4.6 kg) per day, the compressor can be relatively small [3 16 16 in. (.8 41 41 cm)]. Any spacecraft system, or other remote location that has a supply of lowpressure oxygen, a method of separating oxygen from cabin air, and a method of compressing the enriched oxygen stream, has the possibility of having a regenerable supply of highpressure, high-purity oxygen that is compact, simple, and safe. If cabin air is modified so there is very little argon, the separator can be smaller, simpler, and use less power.

Effect of Hydrologic and Geochemical Conditions on Oxygen-Enhanced Bioremediation in a Gasoline-Contaminated Aquifer

USGS Publications Warehouse

Landmeyer, J.E.; Bradley, P.M.

2003-01-01

The effect of pre-existing factors, e.g., hydrologic, geochemical, and microbiological properties, on the results of oxygen addition to a reformulated gasoline-contaminated groundwater system was studied. Oxygen addition with an oxygen-release compound (a proprietary form of magnesium peroxide produced different results with respect to dissolved oxygen (DO) generation and contaminant decrease in the two locations. Oxygen-release compound injected at the former UST source area did not significantly change measured concentrations of DO, benzene, toluene, or MTBE. Conversely, oxygen-release compound injected 200 m downgradient of the former UST source area rapidly increased DO levels, and benzene, toluene, and MTBE concentrations decreased substantially. The different results could be related to differences in hydrologic and geochemical conditions that characterized the two locations prior to oxygen addition. The lack of recharge to ground water in the paved UST source area led to a much larger geochemical sink for DO compared to ground water in the unpaved area.

Expression and characterization of recombinant bifunctional enzymes with glutathione peroxidase and superoxide dismutase activities.

PubMed

Guan, Tuchen; Song, Jian; Wang, Yanan; Guo, Liying; Yuan, Lin; Zhao, Yingding; Gao, Yuan; Lin, Liangru; Wang, Yali; Wei, Jingyan

2017-09-01

To balance the production and decomposition of reactive oxygen species, living organisms have generated antioxidant enzymes and non-enzymatic antioxidant defense systems. Glutathione peroxidase (GPx) and superoxide dismutase (SOD) are two important antioxidant enzymes. Apart from their catalytic functions, they protect each other, resulting in more efficient removal of reactive oxygen species, protection of cells against injury, and maintenance of the normal metabolism of reactive oxygen species. SOD catalyzes the dismutation of the superoxide anion (O 2 •- ) to oxygen (O 2 ) and hydrogen peroxide (H 2 O 2 ). H 2 O 2 is then detoxified to water by GPx. In this study, human GPx1 Ser and the Alvinella pompejana SOD (ApSOD) gene were used to design and generate several recombinant proteins with both GPx and SOD activities by combining traditional fusion protein technology, a cysteine auxotrophic expression system, and a single protein production (SPP) system. Among the fusion proteins, Se-hGPx1 Ser -L-ApSOD exhibited the highest SOD and GPx activities. Additional research was conducted to better understand the properties of Se-hGPx1 Ser -L-ApSOD. The synergism of Se-hGPx1 Ser -L-ApSOD was evaluated by using an in vitro model. This research may facilitate future studies on the cooperation and catalytic mechanisms of GPx and SOD. We believe that the bifunctional enzyme has potential applications as a potent antioxidant. Copyright © 2017 Elsevier Inc. All rights reserved.

Oxygen Nanobubble Tracking by Light Scattering in Single Cells and Tissues.

PubMed

Bhandari, Pushpak; Wang, Xiaolei; Irudayaraj, Joseph

2017-03-28

Oxygen nanobubbles (ONBs) have significant potential in targeted imaging and treatment in cancer diagnosis and therapy. Precise localization and tracking of single ONBs is demonstrated based on hyperspectral dark-field microscope (HSDFM) to image and track single oxygen nanobubbles in single cells. ONBs were proposed as promising contrast-generating imaging agents due to their strong light scattering generated from nonuniformity of refractive index at the interface. With this powerful platform, we have revealed the trajectories and quantities of ONBs in cells, and demonstrated the relation between the size and diffusion coefficient. We have also evaluated the presence of ONBs in the nucleus with respect to an increase in incubation time and have quantified the uptake in single cells in ex vivo tumor tissues. Our results demonstrate that HSDFM can be a versatile platform to detect and measure cellulosic nanoparticles at the single-cell level and to assess the dynamics and trajectories of this delivery system.

Silicon Micropore-Based Parallel Plate Membrane Oxygenator.

PubMed

Dharia, Ajay; Abada, Emily; Feinberg, Benjamin; Yeager, Torin; Moses, Willieford; Park, Jaehyun; Blaha, Charles; Wright, Nathan; Padilla, Benjamin; Roy, Shuvo

2018-02-01

Extracorporeal membrane oxygenation (ECMO) is a life support system that circulates the blood through an oxygenating system to temporarily (days to months) support heart or lung function during cardiopulmonary failure until organ recovery or replacement. Currently, the need for high levels of systemic anticoagulation and the risk for bleeding are main drawbacks of ECMO that can be addressed with a redesigned ECMO system. Our lab has developed an approach using microelectromechanical systems (MEMS) fabrication techniques to create novel gas exchange membranes consisting of a rigid silicon micropore membrane (SμM) support structure bonded to a thin film of gas-permeable polydimethylsiloxane (PDMS). This study details the fabrication process to create silicon membranes with highly uniform micropores that have a high level of pattern fidelity. The oxygen transport across these membranes was tested in a simple water-based bench-top set-up as well in a porcine in vivo model. It was determined that the mass transfer coefficient for the system using SµM-PDMS membranes was 3.03 ± 0.42 mL O 2 min -1 m -2 cm Hg -1 with pure water and 1.71 ± 1.03 mL O 2 min -1 m -2 cm Hg -1 with blood. An analytic model to predict gas transport was developed using data from the bench-top experiments and validated with in vivo testing. This was a proof of concept study showing adequate oxygen transport across a parallel plate SµM-PDMS membrane when used as a membrane oxygenator. This work establishes the tools and the equipoise to develop future generations of silicon micropore membrane oxygenators. © 2017 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Non-photochemical production of singlet oxygen via activation of persulfate by carbon nanotubes.

PubMed

Cheng, Xin; Guo, Hongguang; Zhang, Yongli; Wu, Xiao; Liu, Yang

2017-04-15

The reaction between persulfate (PS) and carbon nanotubes (CNTs) for the degradation of 2,4-dichlorophenol (2,4-DCP) was investigated. It was demonstrated that CNTs could efficiently activate PS for the degradation of 2,4-DCP. Results suggested that the neither hydroxyl radical (OH) nor sulfate radical (SO 4 - ) was produced therein. For the first time, the generation of singlet oxygen ( 1 O 2 ) was proved by several methods including electron paramagnetic resonance spectrometry (EPR) and liquid chromatography mass spectrometry measurements. Moreover, the generation of the superoxide radical as a precursor of the singlet oxygen was also confirmed by using certain scavengers and EPR measurement, in which the presence of molecular oxygen was not required as a precursor of 1 O 2 . The efficient generation of 1 O 2 using the PS/CNTs system without any light irradiation can be employed for the selective oxidation of aqueous organic compounds under neutral conditions with the mineralization and toxicity evaluated. A kinetic model was developed to theoretically evaluate the adsorption and oxidation of 2,4-DCP on the CNTs. Accordingly, a catalytic mechanism was proposed involving the formation of a dioxirane intermediate between PS and CNTs, and the subsequent decomposition of this intermediate into 1 O 2 . Copyright © 2017 Elsevier Ltd. All rights reserved.

Prospects of in vivo singlet oxygen luminescence monitoring: Kinetics at different locations on living mice.

PubMed

Pfitzner, Michael; Schlothauer, Jan C; Bastien, Estelle; Hackbarth, Steffen; Bezdetnaya, Lina; Lassalle, Henri-Pierre; Röder, Beate

2016-06-01

Singlet oxygen observation is considered a valuable tool to assess and optimize PDT treatment. In complex systems, such as tumors in vivo, only the direct, time-resolved singlet oxygen luminescence detection can give reliable information about generation and interaction of singlet oxygen. Up to now, evaluation of kinetics was not possible due to insufficient signal-to-noise ratio. Here we present high signal-to-noise ratio singlet oxygen luminescence kinetics obtained in mouse tumor model under PDT relevant conditions. A highly optimized system based on a custom made laser diode excitation source and a high aperture multi-furcated fiber, utilizing a photomultiplier tube with a multi photon counting device was used. Luminescence kinetics with unsurpassed signal-to-noise ratio were gained from tumor bearing nude mice in vivo upon topic application, subcutaneous injection as well as intravenous injection of different photosensitizers (chlorin e6 and dendrimer formulations of chlorin e6). Singlet oxygen kinetics in appropriate model systems are discussed to facilitate the interpretation of complex kinetics obtained from in vivo tumor tissue. This is the first study addressing the complexity of singlet oxygen luminescence kinetics in tumor tissue. At present, further investigations are needed to fully explain the processes involved. Nevertheless, the high signal-to-noise ratio proves the applicability of direct time-resolved singlet oxygen luminescence detection as a prospective tool for monitoring photodynamic therapy. Copyright © 2016 Elsevier B.V. All rights reserved.

Performance Characteristics of Jet-type Generator of Singlet Oxygen for Supersonic Chemical Oxygen-Iodine Laser*1

NASA Astrophysics Data System (ADS)

Kodymová, Jarmila; Špalek, Otomar

1998-01-01

A jet-type singlet oxygen generator based on a gas-liquid chemical reaction yielding singlet oxygen, O2(1Δ g), for pumping the supersonic chemical oxygen-iodine laser was investigated. In addition to O2(1Δ g) and residual chlorine concentrations, a content of water formed during O2(1Δ g) generation was estimated (because of its detrimental effect on lasing) in gas flowing from the generator to the laser active region. The experimental conditions were determined under which an effect of liquid droplets escaping from the generator was negligible, and accordingly, a content of water vapour was suppressed to a value corresponding to the saturated water vapour pressure. It was also proved that a reduction in the relative water content, and a consequent increase in the laser output power, could be achieved by increasing peroxide and hydroxide concentration in the generator liquid, and by decreasing a liquid temperature and a total pressure in the generator.

Regenerative Environmental Control and Life Support System Diagram

NASA Technical Reports Server (NTRS)

2000-01-01

This diagram shows the flow of recyclable resources in the International Space Station (ISS). The Environmental Control and Life Support System (ECLSS) Group of the Flight Projects Directorate at the Marshall Space Flight Center is responsible for the regenerative ECLSS hardware, as well as providing technical support for the rest of the system. The regenerative ECLSS, whose main components are the Water Recovery System (WRS), and the Oxygen Generation System (OGS), reclaims and recycles water and oxygen. The ECLSS maintains a pressurized habitation environment, provides water recovery and storage, maintains and provides fire detection / suppression, and provides breathable air and a comfortable atmosphere in which to live and work within the ISS. The ECLSS hardware will be located in the Node 3 module of the ISS.

Escherichia coli avoids high dissolved oxygen stress by activation of SoxRS and manganese-superoxide dismutase.

PubMed

Baez, Antonino; Shiloach, Joseph

2013-03-12

High concentrations of reactive oxygen species (ROS) were reported to cause oxidative stress to E. coli cells associated with reduced or inhibited growth. The high ROS concentrations described in these reports were generated by exposing the bacteria to H2O2 and superoxide-generating chemicals which are non-physiological growth conditions. However, the effect of molecular oxygen on oxidative stress response has not been evaluated. Since the use of oxygen-enriched air is a common strategy to support high density growth of E. coli, it was important to investigate the effect of high dissolved oxygen concentrations on the physiology and growth of E. coli and the way it responds to oxidative stress. To determine the effect of elevated oxygen concentrations on the growth characteristics, specific gene expression and enzyme activity in E. coli, the parental and SOD-deficient strain were evaluated when the dissolved oxygen (dO2) level was increased from 30% to 300%. No significant differences in the growth parameters were observed in the parental strain except for a temporary decrease of the respiration and acetate accumulation profile. By performing transcriptional analysis, it was determined that the parental strain responded to the oxidative stress by activating the SoxRS regulon. However, following the dO2 switch, the SOD-deficient strain activated both the SoxRS and OxyR regulons but it was unable to resume its initial growth rate. The transcriptional analysis and enzyme activity results indicated that when E. coli is exposed to dO2 shift, the superoxide stress regulator SoxRS is activated and causes the stimulation of the superoxide dismutase system. This enables the E. coli to protect itself from the poisoning effects of oxygen. The OxyR protecting system was not activated, indicating that H2O2 did not increase to stressing levels.

Escherichia coli avoids high dissolved oxygen stress by activation of SoxRS and manganese-superoxide dismutase

PubMed Central

2013-01-01

Background High concentrations of reactive oxygen species (ROS) were reported to cause oxidative stress to E. coli cells associated with reduced or inhibited growth. The high ROS concentrations described in these reports were generated by exposing the bacteria to H2O2 and superoxide-generating chemicals which are non-physiological growth conditions. However, the effect of molecular oxygen on oxidative stress response has not been evaluated. Since the use of oxygen-enriched air is a common strategy to support high density growth of E. coli, it was important to investigate the effect of high dissolved oxygen concentrations on the physiology and growth of E. coli and the way it responds to oxidative stress. Results To determine the effect of elevated oxygen concentrations on the growth characteristics, specific gene expression and enzyme activity in E. coli, the parental and SOD-deficient strain were evaluated when the dissolved oxygen (dO2) level was increased from 30% to 300%. No significant differences in the growth parameters were observed in the parental strain except for a temporary decrease of the respiration and acetate accumulation profile. By performing transcriptional analysis, it was determined that the parental strain responded to the oxidative stress by activating the SoxRS regulon. However, following the dO2 switch, the SOD-deficient strain activated both the SoxRS and OxyR regulons but it was unable to resume its initial growth rate. Conclusion The transcriptional analysis and enzyme activity results indicated that when E. coli is exposed to dO2 shift, the superoxide stress regulator SoxRS is activated and causes the stimulation of the superoxide dismutase system. This enables the E. coli to protect itself from the poisoning effects of oxygen. The OxyR protecting system was not activated, indicating that H2O2 did not increase to stressing levels. PMID:23497217

Electricity generation directly using human feces wastewater for life support system

NASA Astrophysics Data System (ADS)

Fangzhou, Du; Zhenglong, Li; Shaoqiang, Yang; Beizhen, Xie; Hong, Liu

2011-05-01

Wastewater reuse and power regeneration are key issues in the research of bioregeneration life support system (BLSS). Microbial fuel cell (MFC) can generate electricity during the process of wastewater treatment, which might be promising to solve the two problems simultaneously. We used human feces wastewater containing abundant organic compounds as the substrate of MFC to generate electricity, and the factors concerning electricity generation capacity were investigated. The removal efficiency of total chemical oxygen demand (TCOD), Soluble chemical oxygen demand (SCOD) and NH4+ reached 71%, 88% and 44%, respectively with two-chamber MFC when it was fed with the actual human feces wastewater and operated for 190 h. And the maximum power density reached 70.8 mW/m 2, which implicated that MFC technology was feasible and appropriate for treating human feces wastewater. In order to improve the power generation of MFC further, human feces wastewater were fermented before poured into MFC, and the result showed that fermentation pretreatment could improve the MFC output obviously. The maximum power density of MFC fed with pretreated human feces wastewater was 22 mW/m 2, which was 47% higher than that of the control without pretreatment (15 mW/m 2). Furthermore, the structure of MFC was studied and it was found that both enlarging the area of electrodes and shortening the distance between electrodes could increase the electricity generation capacity. Finally, an automatic system, controlled by time switches and electromagnetic valves, was established to process one person's feces wastewater (1 L/d) while generating electricity. The main parts of this system comprised a pretreatment device and 3 one-chamber air-cathode MFCs. The total power could reach 787.1 mW and power density could reach the maximum of about 240 mW/m 2.

78 FR 64162 - Airworthiness Directives; Airbus Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-28

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

Mimicking Natural Photosynthesis: Solar to Renewable H2 Fuel Synthesis by Z-Scheme Water Splitting Systems

PubMed Central

2018-01-01

Visible light-driven water splitting using cheap and robust photocatalysts is one of the most exciting ways to produce clean and renewable energy for future generations. Cutting edge research within the field focuses on so-called “Z-scheme” systems, which are inspired by the photosystem II–photosystem I (PSII/PSI) coupling from natural photosynthesis. A Z-scheme system comprises two photocatalysts and generates two sets of charge carriers, splitting water into its constituent parts, hydrogen and oxygen, at separate locations. This is not only more efficient than using a single photocatalyst, but practically it could also be safer. Researchers within the field are constantly aiming to bring systems toward industrial level efficiencies by maximizing light absorption of the materials, engineering more stable redox couples, and also searching for new hydrogen and oxygen evolution cocatalysts. This review provides an in-depth survey of relevant Z-schemes from past to present, with particular focus on mechanistic breakthroughs, and highlights current state of the art systems which are at the forefront of the field. PMID:29676566

Mimicking Natural Photosynthesis: Solar to Renewable H2 Fuel Synthesis by Z-Scheme Water Splitting Systems.

PubMed

Wang, Yiou; Suzuki, Hajime; Xie, Jijia; Tomita, Osamu; Martin, David James; Higashi, Masanobu; Kong, Dan; Abe, Ryu; Tang, Junwang

2018-05-23

Visible light-driven water splitting using cheap and robust photocatalysts is one of the most exciting ways to produce clean and renewable energy for future generations. Cutting edge research within the field focuses on so-called "Z-scheme" systems, which are inspired by the photosystem II-photosystem I (PSII/PSI) coupling from natural photosynthesis. A Z-scheme system comprises two photocatalysts and generates two sets of charge carriers, splitting water into its constituent parts, hydrogen and oxygen, at separate locations. This is not only more efficient than using a single photocatalyst, but practically it could also be safer. Researchers within the field are constantly aiming to bring systems toward industrial level efficiencies by maximizing light absorption of the materials, engineering more stable redox couples, and also searching for new hydrogen and oxygen evolution cocatalysts. This review provides an in-depth survey of relevant Z-schemes from past to present, with particular focus on mechanistic breakthroughs, and highlights current state of the art systems which are at the forefront of the field.

Hydrogen gas alleviates oxygen toxicity by reducing hydroxyl radical levels in PC12 cells

PubMed Central

Yu, Junchao; Yu, Qiuhong; Liu, Yaling; Zhang, Ruiyun; Xue, Lianbi

2017-01-01

Hyperbaric oxygen (HBO) therapy through breathing oxygen at the pressure of above 1 atmosphere absolute (ATA) is useful for varieties of clinical conditions, especially hypoxic-ischemic diseases. Because of generation of reactive oxygen species (ROS), breathing oxygen gas at high pressures can cause oxygen toxicity in the central nervous system, leading to multiple neurological dysfunction, which limits the use of HBO therapy. Studies have shown that Hydrogen gas (H2) can diminish oxidative stress and effectively reduce active ROS associated with diseases. However, the effect of H2 on ROS generated from HBO therapy remains unclear. In this study, we investigated the effect of H2 on ROS during HBO therapy using PC12 cells. PC12 cells cultured in medium were exposed to oxygen gas or mixed oxygen gas and H2 at 1 ATA or 5 ATA. Cells viability and oxidation products and ROS were determined. The data showed that H2 promoted the cell viability and inhibited the damage in the cell and mitochondria membrane, reduced the levels of lipid peroxidation and DNA oxidation, and selectively decreased the levels of •OH but not disturbing the levels of O2•-, H2O2, or NO• in PC12 cells during HBO therapy. These results indicated that H2 effectively reduced •OH, protected cells against oxygen toxicity resulting from HBO therapy, and had no effect on other ROS. Our data supported that H2 could be potentially used as an antioxidant during HBO therapy. PMID:28362819

29 CFR 1910.253 - Oxygen-fuel gas welding and cutting.

Code of Federal Regulations, 2010 CFR

2010-07-01

... prohibited in outside generator houses or inside generator rooms. (D) Water shall not be supplied through a... chamber shall always be flushed out with water, renewing the water supply in accordance with the.... Workmen in charge of the oxygen or fuel-gas supply equipment, including generators, and oxygen or fuel-gas...

Generation of hydroxyl radicals and singlet oxygen during oxidation of rhododendrol and rhododendrol-catechol.

PubMed

Miyaji, Akimitsu; Gabe, Yu; Kohno, Masahiro; Baba, Toshihide

2017-03-01

The generation of hydroxyl radicals and singlet oxygen during the oxidation of 4-(4-hydroxyphenyl)-2-butanol (rhododendrol) and 4-(3,4-dihydroxyphenyl)-2-butanol (rhododendrol-catechol) with mushroom tyrosinase in a phosphate buffer (pH 7.4) was examined as the model for the reactive oxygen species generation via the two rhododendrol compounds in melanocytes. The reaction was performed in the presence of 5,5-dimethyl-1-pyrroline- N -oxide (DMPO) spin trap reagents for hydroxyl radical or 2,2,6,6-tetramethyl-4-piperidone (4-oxo-TEMP), an acceptor of singlet oxygen, and their electron spin resonances were measured. An increase in the electron spin resonances signal attributable to the adduct of DMPO reacting with the hydroxyl radical and that of 4-oxo-TEMP reacting with singlet oxygen was observed during the tyrosinase-catalyzed oxidation of rhododendrol and rhododendrol-catechol, indicating the generation of hydroxyl radical and singlet oxygen. Moreover, hydroxyl radical generation was also observed in the autoxidation of rhododendrol-catechol. We show that generation of intermediates during tyrosinase-catalyzed oxidation of rhododendrol enhances oxidative stress in melanocytes.

Cytochrome c-promoted cardiolipin oxidation generates singlet molecular oxygen.

PubMed

Miyamoto, Sayuri; Nantes, Iseli L; Faria, Priscila A; Cunha, Daniela; Ronsein, Graziella E; Medeiros, Marisa H G; Di Mascio, Paolo

2012-10-01

The interaction of cytochrome c (cyt c) with cardiolipin (CL) induces protein conformational changes that favor peroxidase activity. This process has been correlated with CL oxidation and the induction of cell death. Here we report evidence demonstrating the generation of singlet molecular oxygen [O(2)((1)Δ(g))] by a cyt c-CL complex in a model membrane containing CL. The formation of singlet oxygen was directly evidenced by luminescence measurements at 1270 nm and by chemical trapping experiments. Singlet oxygen generation required cyt c-CL binding and occurred at pH values higher than 6, consistent with lipid-protein interactions involving fully deprotonated CL species and positively charged residues in the protein. Moreover, singlet oxygen formation was specifically observed for tetralinoleoyl CL species and was not observed with monounsaturated and saturated CL species. Our results show that there are at least two mechanisms leading to singlet oxygen formation: one with fast kinetics involving the generation of singlet oxygen directly from CL hydroperoxide decomposition and the other involving CL oxidation. The contribution of the first mechanism was clearly evidenced by the detection of labeled singlet oxygen [(18)O(2)((1)Δ(g))] from liposomes supplemented with 18-oxygen-labeled CL hydroperoxides. However quantitative analysis showed that singlet oxygen yield from CL hydroperoxides was minor (<5%) and that most of the singlet oxygen is formed from the second mechanism. Based on these data and previous findings we propose a mechanism of singlet oxygen generation through reactions involving peroxyl radicals (Russell mechanism) and excited triplet carbonyl intermediates (energy transfer mechanism).

Near-Infrared Plasmon-Assisted Water Oxidation.

PubMed

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

2012-05-17

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

Development of a non-cryogenic nitrogen/oxygen supply system. [for spacecraft environments

NASA Technical Reports Server (NTRS)

1977-01-01

Modular components were refined or replaced to improve the performance of the electrolysis module in a system which generates both oxygen and hydrogen from hydrazine hydrate. Significant mechanical and electrical performance improvements were achieved in the cathode. Improvements were also made in the phase separation area but at considerable cost in time and money and to the detriment of other investigative areas. Only the pump/bubble separator failed in a manner necessitating redesign. Its failure was, however, due to its being operated above the temperature range for which it was designed. The basic electrolysis cell design was not changed.

Results of Steam-Water-Oxygen Treatment of the Inside of Heating Surfaces in Heat-Recovery Steam Generators of the PGU-800 Power Unit at the Perm' District Thermal Power Station

NASA Astrophysics Data System (ADS)

Ovechkina, O. V.; Zhuravlev, L. S.; Drozdov, A. A.; Solomeina, S. V.

2018-05-01

Prestarting, postinstallation steam-water-oxygen treatment (SWOT) of the natural circulation/steam reheat heat-recovery steam generators (HRSG) manufactured by OAO Krasny Kotelshchik was performed at the PGU-800 power unit of the Perm District Thermal Power Station (GRES). Prior to SWOT, steam-oxygen cleaning, passivation, and preservation of gas condensate heaters (GCH) of HRSGs were performed for 10 h using 1.3MPa/260°C/70 t/h external steam. After that, test specimens were cut out that demonstrated high strength of the passivating film. SWOT of the inside of the heating surfaces was carried out during no-load operation of the gas turbine unit with an exhaust temperature of 280-300°C at the HRSG inlet. The steam turbine was shutdown, and the generated steam was discharged into the atmosphere. Oxygen was metered into the discharge pipeline of the electricity-driven feed pumps and downcomers of the evaporators. The behavior of the concentration by weight of iron compounds and the results of investigation of cutout specimens by the drop or potentiometric method indicate that the steam-water-oxygen process makes it possible to remove corrosion products and reduce the time required to put a boiler into operation. Unlike other processes, SWOT does not require metal-intensive cleaning systems, temporary metering stations, and structures for collection of the waste solution.

High-Pressure Oxygen Generation for Outpost EVA Study

NASA Technical Reports Server (NTRS)

Jeng, Frank F.; Conger, Bruce; Ewert, Michael K.; Anderson, Molly S.

2009-01-01

The amount of oxygen consumption for crew extravehicular activity (EVA) in future lunar exploration missions will be significant. Eight technologies to provide high pressure EVA O2 were investigated. They are: high pressure O2 storage, liquid oxygen (LOX) storage followed by vaporization, scavenging LOX from Lander followed by vaporization, LOX delivery followed by sorption compression, water electrolysis followed by compression, stand-alone high pressure water electrolyzer, Environmental Control and Life Support System (ECLSS) and Power Elements sharing a high pressure water electrolyzer, and ECLSS and In-Situ Resource Utilization (ISRU) Elements sharing a high pressure electrolyzer. A trade analysis was conducted comparing launch mass and equivalent system mass (ESM) of the eight technologies in open and closed ECLSS architectures. Technologies considered appropriate for the two architectures were selected and suggested for development.

Oxygen Consumption and Usage During Physical Exercise: The Balance Between Oxidative Stress and ROS-Dependent Adaptive Signaling

PubMed Central

Zhao, Zhongfu; Koltai, Erika; Ohno, Hideki; Atalay, Mustafa

2013-01-01

Abstract The complexity of human DNA has been affected by aerobic metabolism, including endurance exercise and oxygen toxicity. Aerobic endurance exercise could play an important role in the evolution of Homo sapiens, and oxygen was not important just for survival, but it was crucial to redox-mediated adaptation. The metabolic challenge during physical exercise results in an elevated generation of reactive oxygen species (ROS) that are important modulators of muscle contraction, antioxidant protection, and oxidative damage repair, which at moderate levels generate physiological responses. Several factors of mitochondrial biogenesis, such as peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α), mitogen-activated protein kinase, and SIRT1, are modulated by exercise-associated changes in the redox milieu. PGC-1α activation could result in decreased oxidative challenge, either by upregulation of antioxidant enzymes and/or by an increased number of mitochondria that allows lower levels of respiratory activity for the same degree of ATP generation. Endogenous thiol antioxidants glutathione and thioredoxin are modulated with high oxygen consumption and ROS generation during physical exercise, controlling cellular function through redox-sensitive signaling and protein–protein interactions. Endurance exercise-related angiogenesis, up to a significant degree, is regulated by ROS-mediated activation of hypoxia-inducible factor 1α. Moreover, the exercise-associated ROS production could be important to DNA methylation and post-translation modifications of histone residues, which create heritable adaptive conditions based on epigenetic features of chromosomes. Accumulating data indicate that exercise with moderate intensity has systemic and complex health-promoting effects, which undoubtedly involve regulation of redox homeostasis and signaling. Antioxid. Redox Signal. 18, 1208–1246. PMID:22978553

Oxygen concentrators for the delivery of supplemental oxygen in remote high-altitude areas.

PubMed

Litch, J A; Bishop, R A

2000-01-01

Oxygen concentrators are a relatively new technology for the delivery of supplemental oxygen. Readily available for domicile use in modern countries, these machines have proved reliable. The application of oxygen concentrators for the supply of medical oxygen in remote high-altitude settings has important cost-saving and supply implications. In our experience at a remote hospital at 3,900 m in the Nepal Himalayas, oxygen concentrators constitute an effective and affordable means to supply medical oxygen. Using an air compressor and 2 zeolite chambers, the machine traps nitrogen from room air compressed to 4 atm, thus concentrating oxygen in the expressed gas. At delivery flow rates of 2 to 5 liters per minute, oxygen concentrations greater than 80% can be maintained. An electric power requirement of less than 400 W can be provided from a variety of sources, including a small gasoline generator, a solar or wind power system with battery store, or a domestic or commercial power source. At our facility, a cost savings of 75% for supplemental oxygen was found in favor of the oxygen concentrator over cylinders (0.17 US cents per liter vs 0.79 US cents per liter).

Cover and startup gas supply system for solid oxide fuel cell generator

DOEpatents

Singh, P.; George, R.A.

1999-07-27

A cover and startup gas supply system for a solid oxide fuel cell power generator is disclosed. Hydrocarbon fuel, such as natural gas or diesel fuel, and oxygen-containing gas are supplied to a burner. Combustion gas exiting the burner is cooled prior to delivery to the solid oxide fuel cell. The system mixes the combusted hydrocarbon fuel constituents with hydrogen which is preferably stored in solid form to obtain a non-explosive gas mixture. The system may be used to provide both non-explosive cover gas and hydrogen-rich startup gas to the fuel cell. 4 figs.

Cover and startup gas supply system for solid oxide fuel cell generator

DOEpatents

Singh, Prabhakar; George, Raymond A.

1999-01-01

A cover and startup gas supply system for a solid oxide fuel cell power generator is disclosed. Hydrocarbon fuel, such as natural gas or diesel fuel, and oxygen-containing gas are supplied to a burner. Combustion gas exiting the burner is cooled prior to delivery to the solid oxide fuel cell. The system mixes the combusted hydrocarbon fuel constituents with hydrogen which is preferably stored in solid form to obtain a non-explosive gas mixture. The system may be used to provide both non-explosive cover gas and hydrogen-rich startup gas to the fuel cell.

Quenching of I(2P 1/2) by O 3 and O( 3P)

NASA Astrophysics Data System (ADS)

Azyazov, V. N.; Antonov, I. O.; Ruffner, S.; Heaven, M. C.

2006-02-01

Oxygen-iodine lasers that utilize electrical or microwave discharges to produce singlet oxygen are currently being developed. The discharge generators differ from conventional chemical singlet oxygen generators in that they produce significant amounts of atomic oxygen. Post-discharge chemistry includes channels that lead to the formation of ozone. Consequently, removal of I(2P 1/2) by O atoms and O 3 may impact the efficiency of discharge driven iodine lasers. In the present study we have measured the rate constants for quenching of I(2P 1/2) by O( 3P) atoms and O 3 using pulsed laser photolysis techniques. The rate constant for quenching by O 3, 1.8x10 -12 cm 3 s -1, was found to be a factor of five smaller than the literature value. The rate constant for quenching by O( 3P) was 1.2x10 -11 cm 3 s -1. This was six times larger than a previously reported upper bound, but consistent with estimates obtained by modeling the kinetics of discharge-driven laser systems.

Effect of Different Silage Storing Conditions on the Oxygen Concentration in the Silo and Fermentation Quality of Rice.

PubMed

Uegaki, Ryuichi; Kawano, Kazuo; Ohsawa, Ryo; Kimura, Toshiyuki; Yamamura, Kohji

2017-06-21

We investigated the effects of different silage storing conditions on the oxygen concentration in the silo and fermentation quality of rice (Oryza sativa L.). Forage rice was ensiled in bottles (with or without space at the bottlemouth, with solid or pinhole cap, and with oxygen scavenger, ethanol transpiration agent, oxygen scavenger and ethanol transpiration agent, or no adjuvant) and stored for 57 days. The oxygen concentration decreased with the addition of the oxygen scavenger and increased with that of the ethanol transpiration agent. The oxygen scavenger facilitated silage fermentation and fungus generation, whereas the ethanol transpiration agent suppressed silage fermentation and fungus generation. However, the combined use of the oxygen scavenger and ethanol transpiration agent facilitated silage fermentation and also suppressed fungus generation. Overall, this study revealed the negative effects of oxygen on the internal silo and the positive effects of the combined use of the oxygen scavenger and ethanol transpiration agent on silage fermentation quality.

Scaling laws for oxygen transport across the space-filling system of respiratory membranes in the human lung

NASA Astrophysics Data System (ADS)

Hou, Chen

Space-filling fractal surfaces play a fundamental role in how organisms function at various levels and in how structure determines function at different levels. In this thesis, we develop a quantitative theory of oxygen transport to and across the surface of the highly branched, space-filling system of alveoli, the fundamental gas exchange unit (acinar airways), in the human lung. Oxygen transport in the acinar airways is by diffusion, and we treat the two steps---diffusion through the branched airways, and transfer across the alveolar membranes---as a stationary diffusion-reaction problem, taking into account that there may be steep concentration gradients between the entrance and remote alveoli (screening). We develop a renormalization treatment of this screening effect and derive an analytic formula for the oxygen current across the cumulative alveolar membrane surface, modeled as a fractal, space-filling surface. The formula predicts the current from a minimum of morphological data of the acinus and appropriate values of the transport parameters, through a number of power laws (scaling laws). We find that the lung at rest operates near the borderline between partial screening and no screening; that it switches to no screening under exercise; and that the computed currents agree with measured values within experimental uncertainties. From an analysis of the computed current as a function of membrane permeability, we find that the space-filling structure of the gas exchanger is simultaneously optimal with respect to five criteria. The exchanger (i) generates a maximum oxygen current at minimum permeability; (ii) 'wastes' a minimum of surface area; (iii) maintains a minimum residence time of oxygen in the acinar airways; (iv) has a maximum fault tolerance to loss of permeability; and (v) generates a maximum current increase when switching from rest to exercise.

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

PubMed

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

2015-07-01

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

Study on Fuel Cell Network System Considering Reduction in Fuel Cell Capacity Using Load Leveling and Heat Release Loss

NASA Astrophysics Data System (ADS)

Obara, Shin'ya; Kudo, Kazuhiko

Reduction in fuel cell capacity linked to a fuel cell network system is considered. When the power demand of the whole network is small, some of the electric power generated by the fuel cell is supplied to a water electrolysis device, and hydrogen and oxygen gases are generated. Both gases are compressed with each compressor and they are stored in cylinders. When the electric demand of the whole network is large, both gases are supplied to the network, and fuel cells are operated by these hydrogen and oxygen gases. Furthermore, an optimization plan is made to minimize the quantity of heat release of the hot water piping that connects each building. Such an energy network is analyzed assuming connection of individual houses, a hospital, a hotel, a convenience store, an office building, and a factory. Consequently, compared with the conventional system, a reduction of 46% of fuel cell capacity is expected.

Characteristics of Honeycomb-Type Oxygen Generator with Electrolyte Based on Doped Bismuth Oxide

NASA Astrophysics Data System (ADS)

Chen, Yu-Wen; Liu, Yi-Xin; Wang, Sea-Fue; Devasenathipathy, Rajkumar

2018-03-01

An oxygen generator using Y-doped Bi2O3 as electrolyte to transport oxygen ions has been developed, having honeycomb-type structure with dimensions of 40 mm × 35 mm × 30 mm and consisting of 13 × 12 channels. External wire circuitry for the channels arrayed using parallel, series, and hybrid connection was evaluated to achieve the best oxygen separation efficiency. It was observed that the oxygen generator with hybrid connection facilitated evolution of oxygen at maximum of 117 sccm and high purity > 99.9% at 550°C under current flow of 14 A. Addition of 5 wt.% silane and 3 wt.% glass-ceramic powder to the Ag slurry used at both electrodes not only increased the coverage of the metal electrode on the ceramic substrate during dip coating but also prevented cracking at the electrode layer of the module under stress from the electric field and temperature during high-temperature operation, thus reducing the decay rate of the oxygen generator in durability testing.

Solar cells for lunar applications by vacuum evaporation of lunar regolith materials

NASA Technical Reports Server (NTRS)

Ignatiev, Alex

1991-01-01

The National Space Exploration Initiative, specifically the Lunar component, has major requirements for technology development of critical systems, one of which is electrical power. The availability of significant electrical power on the surface of the Moon is a principal driver defining the complexity of the lunar base. Proposals to generate power on the Moon include both nuclear and solar (photovoltaic) systems. A more efficient approach is to attempt utilization of the existing lunar resources to generate the power systems. Synergism may occur from the fact that there have already been lunar materials processing techniques proposed for the extraction of oxygen that would have, as by-products, materials that could be specifically used to generate solar cells. The lunar environment is a vacuum with pressures generally in the 1 x 10(exp -10) torr range. Such conditions provide an ideal environment for direct vacuum deposition of thin film solar cells using the waste silicon, iron, and TiO2 available from the lunar regolith processing meant to extract oxygen. It is proposed, therefore, to grow by vacuum deposition, thin film silicon solar cells from the improved regolith processing by-products.

Sustained contraction and endothelial dysfunction induced by reactive oxygen species in porcine coronary artery.

PubMed

Ishihara, Yasuhiro; Sekine, Masaya; Hatano, Ai; Shimamoto, Norio

2008-09-01

A combination of purine and xanthine oxidase (XOD) dose-dependently elicited sustained contraction of porcine coronary arterial rings and resulted in increased concentrations of superoxide anions and hydrogen peroxide. These contractile responses appeared, with a delay, after the application of purine and XOD, used as a reactive oxygen species (ROS)-generating system. Coronary arteries precontracted with prostaglandin F(2alpha) failed to relax in response to substance P after exposing the arterial preparation to this ROS-generating system. The contractile response of the coronary artery to the ROS-generating system was almost completely inhibited by catalase (130 U/ml), and was partially inhibited by superoxide dismutase (60 U/ml), or mannitol (30 mM). A voltage-dependent L-type Ca(2+) channel antagonist, nicardipine, had no effect on contraction. Dysfunction of endothelial cells was completely prevented by catalase, but not by superoxide dismutase or mannitol. These results suggest that superoxide anions, hydrogen peroxide and hydroxyl radicals might be involved in eliciting sustained, delayed-onset coronary artery contraction, which is not related to L-type Ca(2+) channels. They also suggest that hydrogen peroxide might play a major role in endothelial dysfunction of the porcine coronary artery.

Inflammation, Oxidative Stress, and Obesity

PubMed Central

Fernández-Sánchez, Alba; Madrigal-Santillán, Eduardo; Bautista, Mirandeli; Esquivel-Soto, Jaime; Morales-González, Ángel; Esquivel-Chirino, Cesar; Durante-Montiel, Irene; Sánchez-Rivera, Graciela; Valadez-Vega, Carmen; Morales-González, José A.

2011-01-01

Obesity is a chronic disease of multifactorial origin and can be defined as an increase in the accumulation of body fat. Adipose tissue is not only a triglyceride storage organ, but studies have shown the role of white adipose tissue as a producer of certain bioactive substances called adipokines. Among adipokines, we find some inflammatory functions, such as Interleukin-6 (IL-6); other adipokines entail the functions of regulating food intake, therefore exerting a direct effect on weight control. This is the case of leptin, which acts on the limbic system by stimulating dopamine uptake, creating a feeling of fullness. However, these adipokines induce the production of reactive oxygen species (ROS), generating a process known as oxidative stress (OS). Because adipose tissue is the organ that secretes adipokines and these in turn generate ROS, adipose tissue is considered an independent factor for the generation of systemic OS. There are several mechanisms by which obesity produces OS. The first of these is the mitochondrial and peroxisomal oxidation of fatty acids, which can produce ROS in oxidation reactions, while another mechanism is over-consumption of oxygen, which generates free radicals in the mitochondrial respiratory chain that is found coupled with oxidative phosphorylation in mitochondria. Lipid-rich diets are also capable of generating ROS because they can alter oxygen metabolism. Upon the increase of adipose tissue, the activity of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), was found to be significantly diminished. Finally, high ROS production and the decrease in antioxidant capacity leads to various abnormalities, among which we find endothelial dysfunction, which is characterized by a reduction in the bioavailability of vasodilators, particularly nitric oxide (NO), and an increase in endothelium-derived contractile factors, favoring atherosclerotic disease. PMID:21686173

Singlet delta oxygen generation for Chemical Oxygen-Iodine Lasers

NASA Astrophysics Data System (ADS)

Georges, E.; Mouthon, A.; Barraud, R.

1991-10-01

The development of Chemical Oxygen-Iodine Lasers is based on the generation of singlet delta oxygen. To improve the overall efficiency of these lasers, it is necessary to increase the generator production and yield of singlet delta oxygen at low and high pressure, respectively, for subsonic and supersonic lasers. Furthermore, the water vapor content must be as low as possible. A generator model, based on gas-liquid reaction and liquid-vapor equilibrium theories associated with thermophysical evaluations is presented. From model predictions, operating conditions have been drawn to attain the following experimental results in a bubble-column: by increasing the superficial gas velocity, the production of singlet delta oxygen is largely improved at low pressure; by mixing chlorine with an inert gas before injection in the reactor, this yield is maintained constant up to higher pressure. A theoretical analysis of these experimental results and their consequences for both subsonic and supersonic lasers are presented.

Nyberg with OGS R&R

NASA Image and Video Library

2013-07-19

ISS036-E-021797 (18 July 2013) --- NASA astronaut Karen Nyberg, Expedition 36 flight engineer, performs a remove and replace of the Oxygen Generation System (OGS) Hydrogen (H2) Sensor in the Tranquility node of the International Space Station.

Recent concepts in missions to Mars - Extraterrestrial processes

NASA Technical Reports Server (NTRS)

Ramohalli, K. N.; Ash, R. L.; Lawton, E. A.; French, J. R.; Frisbee, R. H.

1986-01-01

This paper presents some recent concepts in Mars Sample Return (MSR) missions that utilize extraterrestrial resources. The concepts examined include the power and energy needs of this mission. It is shown that solar energy is not especially attractive. Radioisotopic power generator and a Rankine cycle use are seen to be viable options. Quantitative estimates, taking into consideration state-of-the-art and projected technologies indicate that the power/energy per se is not critical to the mission - but reliability is. Hence, various modern options for the components of the power generation and utilization are discussed. The dramatic savings in Shuttle (or other) vehicle launches are quantitatively plotted. The basic system that is discussed here is the production of hydrocarbon (methane) fuel and oxygen from Martian atmosphere. For the simplest mission, it is seen that earth-carried methane burned with oxygen produced on site provides the best system.

Orbital Engineering in Nickelate Heterostructures Driven by Anisotropic Oxygen Hybridization rather than Orbital Energy Levels

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

Fabbris, G.; Meyers, D.; Okamoto, J.

We used resonant inelastic x-ray scattering to investigate the electronic origin of orbital polarization in nickelate heterostructures taking LaTiO 3-LaNiO 3-3×(LaAlO 3), a system with exceptionally large polarization, as a model system. Furthermore, we find that heterostructuring generates only minor changes in the Ni 3d orbital energy levels, contradicting the often-invoked picture in which changes in orbital energy levels generate orbital polarization. Instead, O K-edge x-ray absorption spectroscopy demonstrates that orbital polarization is caused by an anisotropic reconstruction of the oxygen ligand hole states. This also provides an explanation for the limited success of theoretical predictions based on tuning orbitalmore » energy levels and implies that future theories should focus on anisotropic hybridization as the most effective means to drive large changes in electronic structure and realize novel emergent phenomena.« less

Orbital Engineering in Nickelate Heterostructures Driven by Anisotropic Oxygen Hybridization rather than Orbital Energy Levels

NASA Astrophysics Data System (ADS)

Fabbris, G.; Meyers, D.; Okamoto, J.; Pelliciari, J.; Disa, A. S.; Huang, Y.; Chen, Z.-Y.; Wu, W. B.; Chen, C. T.; Ismail-Beigi, S.; Ahn, C. H.; Walker, F. J.; Huang, D. J.; Schmitt, T.; Dean, M. P. M.

2016-09-01

Resonant inelastic x-ray scattering is used to investigate the electronic origin of orbital polarization in nickelate heterostructures taking LaTiO3-LaNiO3-3 ×(LaA l O3) , a system with exceptionally large polarization, as a model system. We find that heterostructuring generates only minor changes in the Ni 3 d orbital energy levels, contradicting the often-invoked picture in which changes in orbital energy levels generate orbital polarization. Instead, O K -edge x-ray absorption spectroscopy demonstrates that orbital polarization is caused by an anisotropic reconstruction of the oxygen ligand hole states. This provides an explanation for the limited success of theoretical predictions based on tuning orbital energy levels and implies that future theories should focus on anisotropic hybridization as the most effective means to drive large changes in electronic structure and realize novel emergent phenomena.

Kinetic theory of oxygen isotopic exchange between minerals and water

USGS Publications Warehouse

Criss, R.E.; Gregory, R.T.; Taylor, H.P.

1987-01-01

Kinetic and mass conservation equations are used to describe oxygen isotopic exchange between minerals and water in "closed" and open hydrothermal systems. In cases where n coexisting mineral phases having different reaction rates are present, the exchange process is described by a system of n + 1 simultaneous differential equations consisting of n pseudo first-order rate equations and a conservation of mass equation. The simultaneous solutions to these equations generate curved exchange trajectories on ??-?? plots. Families of such trajectories generated under conditions allowing for different fluid mole fractions, different fluid isotopic compositions, or different fluid flow rates are connected by positive-sloped isochronous lines. These isochrons reproduce the effects observed in hydrothermally exchanged mineral pairs including 1) steep positive slopes, 2) common reversals in the measured fractionation factors (??), and 3) measured fractionations that are highly variable over short distances where no thermal gradient can be geologically demonstrated. ?? 1987.

Orbital Engineering in Nickelate Heterostructures Driven by Anisotropic Oxygen Hybridization rather than Orbital Energy Levels

DOE PAGES

Fabbris, G.; Meyers, D.; Okamoto, J.; ...

2016-09-30

We used resonant inelastic x-ray scattering to investigate the electronic origin of orbital polarization in nickelate heterostructures taking LaTiO 3-LaNiO 3-3×(LaAlO 3), a system with exceptionally large polarization, as a model system. Furthermore, we find that heterostructuring generates only minor changes in the Ni 3d orbital energy levels, contradicting the often-invoked picture in which changes in orbital energy levels generate orbital polarization. Instead, O K-edge x-ray absorption spectroscopy demonstrates that orbital polarization is caused by an anisotropic reconstruction of the oxygen ligand hole states. This also provides an explanation for the limited success of theoretical predictions based on tuning orbitalmore » energy levels and implies that future theories should focus on anisotropic hybridization as the most effective means to drive large changes in electronic structure and realize novel emergent phenomena.« less

[Biochemical basis of the single theory of aging. Part II. The cell aerobic status, the hypoxia resistance and proliferation].

PubMed

Kirova, Iu I; Borodulin, V B

2009-01-01

Cells of an organism have different parameters of morphology, metabolism, isoenzyme composition, proliferation and respiration. These differences are derivatives of the cell aerobic status. The primary oxygen acceptors are the "macroscopic" cells (neurons, cardiocytes). In these obligatory aerobic cells oxygen is converted into metabolic water directly by the cytochrome oxidase activity. The secondary oxygen acceptors are the "microscopic" cells (other single-nucleus cells). In these facultative aerobic cells oxygen is converted into hydrogen peroxide. The intracellular labile peroxide pool of oxygen is formed by the oxidase, cytochrome P450, superoxide dismutase, and the mitochondrial cyan-resistance oxidase. The mitochondrial isoenzymes of catalase, glutation peroxidase, and thioredoxin reductase convert hydrogen peroxide into molecular oxygen and form high local oxygen concentration as the major factor for the cytochrome oxidase activity. The hypoxia resistance is increased by the growth of the functional activity of the peroxide-generative and peroxide-mobilizative enzyme systems.

Chemiluminescence accompanied by the reaction of acridinium ester and manganese (II).

PubMed

Ren, Lingling; Cui, Hua

2014-11-01

An acridinium ester (AE) alkaline solution can react with Mn(II) to generate a strong chemiluminescence (CL) centered at 435 nm. The effects of reaction conditions such as pH and Mn(II) concentration on CL intensity were examined. In order to explore the CL mechanism, the effect of oxygen on the CL reaction was examined and an X-ray photoelectron spectroscopy study of the reaction precipitate was carried out. The results indicated that oxygen participated in the CL reaction and Mn(IV) was the primary product in the system. A possible mechanism was proposed that involved two pathways: (1) dissolved oxygen was reduced to reactive oxygen radicals by Mn(II), these reactive intermediates then reacted with AE to produce excited state acridone; (2) Mn(II) could reduce AE to partly reduced AE, which then reacted with oxygen to form excited state acridone. The reactions of other metal ions with AE were also tested, and only Mn(II) was shown to trigger strong CL emission of AE, which indicated that the system had good selectivity for Mn(II). Copyright © 2014 John Wiley & Sons, Ltd.

STS-84 oxygen generator for Mir installation

NASA Technical Reports Server (NTRS)

1997-01-01

McDonnell Douglas-SPACEHAB technicians strap in place a Russian- made oxygen generator on the floor of a SPACEHAB Double Module, being prepared for flight in the SPACEHAB Payload Processing Facility. From left, are Mark Halavin and Marc Tuttle. The oxygen generator, manufactured in Russia by RSC Energia, will be carried aboard the Space Shuttle Atlantis on Mission STS-84 for the Shuttles scheduled docking with the Russian Space Station Mir next month. The nearly 300-pound generator will replace one of two Mir units that have been malfunctioning recently. The generator functions by electrolysis, which separates water into its oxygen and hydrogen components. The hydrogen is vented and the oxygen is used for breathing by the Mir crew. The generator is 4.2 feet in length and 1.4 feet in diameter. STS-84, which is planned to include a Mir crew exchange of astronaut C. Michael Foale for Jerry M. Linenger, is targeted for a May 15 liftoff. It will be the sixth Shuttle-Mir docking.

STS-84 oxygen generator for Mir installation

NASA Technical Reports Server (NTRS)

1997-01-01

McDonnell Douglas-SPACEHAB technicians oversee the move of a Russian-made oxygen generator to a SPACEHAB Double Module, at rear, in the SPACEHAB Payload Processing Facility. With faces visible in center foreground, from left, are Mark Halavin and Marc Tuttle; Mike Vawter is at far right. The oxygen generator, manufactured in Russia by RSC Energia, will be carried aboard the Space Shuttle Atlantis on Mission STS-84 for the Shuttles scheduled docking with the Russian Space Station Mir next month. The nearly 300-pound generator will replace one of two Mir units that have been malfunctioning recently. The generator functions by electrolysis, which separates water into its oxygen and hydrogen components. The hydrogen is vented and the oxygen is used for breathing by the Mir crew. The generator is 4.2 feet in length and 1.4 feet in diameter. STS-84, which is planned to include a Mir crew exchange of astronaut C. Michael Foale for Jerry M. Linenger, is targeted for a May 15 liftoff. It will be the sixth Shuttle-Mir docking.

Singlet Oxygen Generation by UVA Light Exposure of Endogenous Photosensitizers

PubMed Central

Baier, Jürgen; Maisch, Tim; Maier, Max; Engel, Eva; Landthaler, Michael; Bäumler, Wolfgang

2006-01-01

UVA light (320–400 nm) has been shown to produce deleterious biological effects in tissue due to the generation of singlet oxygen by substances like flavins or urocanic acid. Riboflavin, flavin mononucleotide (FMN), flavin adenine dinucleotide (FAD), β-nicotinamide adenine dinucleotide (NAD), and β-nicotinamide adenine dinucleotide phosphate (NADP), urocanic acid, or cholesterol in solution were excited at 355 nm. Singlet oxygen was directly detected by time-resolved measurement of its luminescence at 1270 nm. NAD, NADP, and cholesterol showed no luminescence signal possibly due to the very low absorption coefficient at 355 nm. Singlet oxygen luminescence of urocanic acid was clearly detected but the signal was too weak to quantify a quantum yield. The quantum yield of singlet oxygen was precisely determined for riboflavin (ΦΔ = 0.54 ± 0.07), FMN (ΦΔ = 0.51 ± 0.07), and FAD (ΦΔ = 0.07 ± 0.02). In aerated solution, riboflavin and FMN generate more singlet oxygen than exogenous photosensitizers such as Photofrin, which are applied in photodynamic therapy to kill cancer cells. With decreasing oxygen concentration, the quantum yield of singlet oxygen generation decreased, which must be considered when assessing the role of singlet oxygen at low oxygen concentrations (inside tissue). PMID:16751234

Unusual Reactivity of the Martian Soil: Oxygen Release Upon Humidification

NASA Technical Reports Server (NTRS)

Yen, A. S.

2002-01-01

Recent lab results show that oxygen evolves from superoxide-coated mineral grains upon exposure to water vapor. This observation is additional support of the hypothesis that UV-generated O2 is responsible for the reactivity of the martian soil. Discussion of current NASA research opportunities, status of various programs within the Solar System Exploration Division, and employment opportunities within NASA Headquarters to support these programs. Additional information is contained in the original extended abstract.

International Space Station (ISS)

NASA Image and Video Library

2000-01-01

This diagram shows the flow of recyclable resources in the International Space Station (ISS). The Environmental Control and Life Support System (ECLSS) Group of the Flight Projects Directorate at the Marshall Space Flight Center is responsible for the regenerative ECLSS hardware, as well as providing technical support for the rest of the system. The regenerative ECLSS, whose main components are the Water Recovery System (WRS), and the Oxygen Generation System (OGS), reclaims and recycles water and oxygen. The ECLSS maintains a pressurized habitation environment, provides water recovery and storage, maintains and provides fire detection / suppression, and provides breathable air and a comfortable atmosphere in which to live and work within the ISS. The ECLSS hardware will be located in the Node 3 module of the ISS.

International Space Station (ISS)

NASA Image and Video Library

2000-01-01

This diagram shows the flow of water recovery and management in the International Space Station (ISS). The Environmental Control and Life Support System (ECLSS) Group of the Flight Projects Directorate at the Marshall Space Flight Center is responsible for the regenerative ECLSS hardware, as well as providing technical support for the rest of the system. The regenerative ECLSS, whose main components are the Water Recovery System (WRS), and the Oxygen Generation System (OGS), reclaims and recycles water oxygen. The ECLSS maintains a pressurized habitation environment, provides water recovery and storage, maintains and provides fire detection/ suppression, and provides breathable air and a comfortable atmosphere in which to live and work within the ISS. The ECLSS hardware will be located in the Node 3 module of the ISS.

Electrochemical Technology for Oxygen Removal and Measurement in the CELSS Test Facility, Engineering Development Unit

NASA Technical Reports Server (NTRS)

Drews, Michael E.; Covington, Al (Technical Monitor)

1994-01-01

The Life Support Flight Program is evaluating regenerative technologies, including those that utilize higher plants, as a means to reduce resupply over long duration space missions. Constructed to assist in the evaluation process is the CELSS Test Facility Engineering Development Unit (CTF-EDU) an environmentally closed (less than 1% mass and thermal leakage) technology test bed. This ground based fully functional prototype is currently configured to support crop growth, utilizing the power, volume and mass resources allocated for two space station racks. Sub-system technologies were selected considering their impact on available resources, their ability to minimize integration issues, and their degree of modularity. Gas specific mass handling is a key sub-system technology for both biological and physical/chemical life support technologies. The CTF-EDU requires such a system to accommodate non-linear oxygen production from crops, by enabling the control system to change and sustain partial pressure set points in the growth volume. Electrochemical cells are one of the technologies that were examined for oxygen handling in the CTF-EDU. They have been additionally considered to meet other regenerative life support functions, such as oxygen generation, the production of potable water from composite waste streams, and for having the potential to integrate life support functions with those of propulsion and energy storage. An oxygen removal system based on an electrochemical cell was chosen for the EDU due to it's low power, volume and mass requirements (10W, 0.000027 cu m, 4.5 kg) and because of the minimal number of integration considerations. Unlike it's competitors, the system doesn't require post treatments of its byproducts, or heat and power intensive regenerations, that also mandate system redundancy or cycling. The EDUs oxygen removal system only requires two resources, which are already essential to controlled plant growth: electricity and water. Additionally, the amount of oxygen that is removed from the EDU is directly proportional to the cell input current via Faraday's constant, potentially allowing for a mol/electron measurement of photosynthetic rate. The currently operative oxygen removal system has maintained reduced oxygen set points within the EDU, and preparation is underway to verify of the accuracy of electrochemical measurement of oxygen production and hence, photosynthesis. This paper examines the working principles of the electrochemical cell, outlines the overall design of the oxygen removal system and its integration with other EDU subsystems, and summarizes test results obtained over crop growth cycles in the CTF-EDU.

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: An optical boiler generating singlet oxygen O2 (a1Δg)

NASA Astrophysics Data System (ADS)

Lipatov, N. I.; Biryukov, A. S.; Gulyamova, E. S.

2008-12-01

An ecologically perfect generator of singlet oxygen O2 (a1Δg) is proposed which fundamentally differs from existing singlet-oxygen generators. Excited O2 (a1Δg) molecules are generated due to interaction of the O2 (X3Σ-g) molecules with a quasi-monochromatic field, which is supplied from an external source to a closed volume — an optical boiler containing oxygen. It is shown that, by pumping continuously the optical boiler by the light field of power ~3×105 W, it is possible to accumulate up to 40% of singlet oxygen (O2(b1Σ+g)) + (O2 (a1Δg)) in the boiler volume during ~10-2 s.

Electricity generation through a photo sediment microbial fuel cell using algae at the cathode.

PubMed

Neethu, B; Ghangrekar, M M

2017-12-01

Sediment microbial fuel cells (SMFCs) are bio-electrochemical devices generating electricity from redox gradients occurring across the sediment-water interface. Sediment microbial carbon-capture cell (SMCC), a modified SMFC, uses algae grown in the overlying water of sediment and is considered as a promising system for power generation along with algal cultivation. In this study, the performance of SMCC and SMFC was evaluated in terms of power generation, dissolved oxygen variations, sediment organic matter removal and algal growth. SMCC gave a maximum power density of 22.19 mW/m 2 , which was 3.65 times higher than the SMFC operated under similar conditions. Sediment organic matter removal efficiencies of 77.6 ± 2.1% and 61.0 ± 1.3% were obtained in SMCC and SMFC, respectively. With presence of algae at the cathode, a maximum chemical oxygen demand and total nitrogen removal efficiencies of 63.3 ± 2.3% (8th day) and 81.6 ± 1.2% (10th day), respectively, were observed. The system appears to be favorable from a resources utilization perspective as it does not depend on external aeration or membranes and utilizes algae and organic matter present in sediment for power generation. Thus, SMCC has proven its applicability for installation in an existing oxidation pond for sediment remediation, algae growth, carbon conversion and power generation, simultaneously.

Characterizing Myeloid Cell Activation in NF1 Vasculopathy

DTIC Science & Technology

2017-07-01

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

Reactive oxygen species generation and signaling in plants

PubMed Central

Tripathy, Baishnab Charan; Oelmüller, Ralf

2012-01-01

The introduction of molecular oxygen into the atmosphere was accompanied by the generation of reactive oxygen species (ROS) as side products of many biochemical reactions. ROS are permanently generated in plastids, peroxisomes, mitochiondria, the cytosol and the apoplast. Imbalance between ROS generation and safe detoxification generates oxidative stress and the accumulating ROS are harmful for the plants. On the other hand, specific ROS function as signaling molecules and activate signal transduction processes in response to various stresses. Here, we summarize the generation of ROS in the different cellular compartments and the signaling processes which are induced by ROS. PMID:23072988

Control of oxygen tension recapitulates zone-specific functions in human liver microphysiology systems.

PubMed

Lee-Montiel, Felipe T; George, Subin M; Gough, Albert H; Sharma, Anup D; Wu, Juanfang; DeBiasio, Richard; Vernetti, Lawrence A; Taylor, D Lansing

2017-10-01

This article describes our next generation human Liver Acinus MicroPhysiology System (LAMPS). The key demonstration of this study was that Zone 1 and Zone 3 microenvironments can be established by controlling the oxygen tension in individual devices over the range of ca. 3 to 13%. The oxygen tension was computationally modeled using input on the microfluidic device dimensions, numbers of cells, oxygen consumption rates of hepatocytes, the diffusion coefficients of oxygen in different materials and the flow rate of media in the MicroPhysiology System (MPS). In addition, the oxygen tension was measured using a ratiometric imaging method with the oxygen sensitive dye, Tris(2,2'-bipyridyl) dichlororuthenium(II) hexahydrate (RTDP) and the oxygen insensitive dye, Alexa 488. The Zone 1 biased functions of oxidative phosphorylation, albumin and urea secretion and Zone 3 biased functions of glycolysis, α1AT secretion, Cyp2E1 expression and acetaminophen toxicity were demonstrated in the respective Zone 1 and Zone 3 MicroPhysiology System. Further improvements in the Liver Acinus MicroPhysiology System included improved performance of selected nonparenchymal cells, the inclusion of a porcine liver extracellular matrix to model the Space of Disse, as well as an improved media to support both hepatocytes and non-parenchymal cells. In its current form, the Liver Acinus MicroPhysiology System is most amenable to low to medium throughput, acute through chronic studies, including liver disease models, prioritizing compounds for preclinical studies, optimizing chemistry in structure activity relationship (SAR) projects, as well as in rising dose studies for initial dose ranging. Impact statement Oxygen zonation is a critical aspect of liver functions. A human microphysiology system is needed to investigate the impact of zonation on a wide range of liver functions that can be experimentally manipulated. Because oxygen zonation has such diverse physiological effects in the liver, we developed and present a method for computationally modeling and measuring oxygen that can easily be implemented in all MPS models. We have applied this method in a liver MPS in which we are then able to control oxygenation in separate devices and demonstrate that zonation-dependent hepatocyte functions in the MPS recapitulate what is known about in vivo liver physiology. We believe that this advance allows a deep experimental investigation on the role of zonation in liver metabolism and disease. In addition, modeling and measuring oxygen tension will be required as investigators migrate from PDMS to plastic and glass devices.

Control of oxygen tension recapitulates zone-specific functions in human liver microphysiology systems

PubMed Central

Lee-Montiel, Felipe T; George, Subin M; Sharma, Anup D; Wu, Juanfang; DeBiasio, Richard; Vernetti, Lawrence A; Taylor, D Lansing

2017-01-01

This article describes our next generation human Liver Acinus MicroPhysiology System (LAMPS). The key demonstration of this study was that Zone 1 and Zone 3 microenvironments can be established by controlling the oxygen tension in individual devices over the range of ca. 3 to 13%. The oxygen tension was computationally modeled using input on the microfluidic device dimensions, numbers of cells, oxygen consumption rates of hepatocytes, the diffusion coefficients of oxygen in different materials and the flow rate of media in the MicroPhysiology System (MPS). In addition, the oxygen tension was measured using a ratiometric imaging method with the oxygen sensitive dye, Tris(2,2′-bipyridyl) dichlororuthenium(II) hexahydrate (RTDP) and the oxygen insensitive dye, Alexa 488. The Zone 1 biased functions of oxidative phosphorylation, albumin and urea secretion and Zone 3 biased functions of glycolysis, α1AT secretion, Cyp2E1 expression and acetaminophen toxicity were demonstrated in the respective Zone 1 and Zone 3 MicroPhysiology System. Further improvements in the Liver Acinus MicroPhysiology System included improved performance of selected nonparenchymal cells, the inclusion of a porcine liver extracellular matrix to model the Space of Disse, as well as an improved media to support both hepatocytes and non-parenchymal cells. In its current form, the Liver Acinus MicroPhysiology System is most amenable to low to medium throughput, acute through chronic studies, including liver disease models, prioritizing compounds for preclinical studies, optimizing chemistry in structure activity relationship (SAR) projects, as well as in rising dose studies for initial dose ranging. Impact statement Oxygen zonation is a critical aspect of liver functions. A human microphysiology system is needed to investigate the impact of zonation on a wide range of liver functions that can be experimentally manipulated. Because oxygen zonation has such diverse physiological effects in the liver, we developed and present a method for computationally modeling and measuring oxygen that can easily be implemented in all MPS models. We have applied this method in a liver MPS in which we are then able to control oxygenation in separate devices and demonstrate that zonation-dependent hepatocyte functions in the MPS recapitulate what is known about in vivo liver physiology. We believe that this advance allows a deep experimental investigation on the role of zonation in liver metabolism and disease. In addition, modeling and measuring oxygen tension will be required as investigators migrate from PDMS to plastic and glass devices. PMID:28409533

Performance calculations for 200-1000 MWe MHD/steam power plants

NASA Technical Reports Server (NTRS)

Staiger, P. J.

1981-01-01

The effects of MHD generator length, level of oxygen enrichment, and oxygen production power on the performance of MHD/steam power plants ranging from 200 to 1000 MW in electrical output are investigated. The plants considered use oxygen enriched combustion air preheated to 1100 F. Both plants in which the MHD generator is cooled with low temperature and pressure boiler feedwater and plants in which the generator is cooled with high temperature and pressure boiler feedwater are considered. For plants using low temperature boiler feedwater for generator cooling the maximum thermodynamic efficiency is obtained with shorter generators and a lower level of oxygen enrichment compared to plants using high temperature boiler feedwater for generator cooling. The generator length at which the maximum plant efficiency occurs increases with power plant size for plants with a generator cooled by low temperature feedwater. Also shown is the relationship of the magnet stored energy requirement of the generator length and the power plant performance. Possible cost/performance tradeoffs between magnet cost and plant performance are indicated.

Continuous process for singlet oxygenation of hydrophobic substrates in microemulsion using a pervaporation membrane.

PubMed

Caron, Laurent; Nardello, Véronique; Mugge, José; Hoving, Erik; Alsters, Paul L; Aubry, Jean-Marie

2005-02-15

Chemically generated singlet oxygen (1O2, 1Deltag) is able to oxidize a great deal of hydrophobic substrates from molybdate-catalyzed hydrogen peroxide decomposition, provided a suitable reaction medium such as a microemulsion system is used. However, high substrate concentrations or poorly reactive organics require large amounts of H2O2 that generate high amounts of water and thus destabilize the system. We report results obtained on combining dark singlet oxygenation of hydrophobic substrates in microemulsions with a pervaporation membrane process. To avoid composition alterations after addition of H2O2 during the peroxidation, the reaction mixture circulates through a ceramic membrane module that enables a partial and selective dewatering of the microemulsion. Optimization phase diagrams of sodium molybdate/water/alcohol/anionic surfactant/organic solvent have been elaborated to maximize the catalyst concentration and therefore the reaction rate. The membrane selectivity towards the mixture constituents has been investigated showing that a high retention is observed for the catalyst, for organic solvents and hydrophobic substrates, but not for n-propanol (cosurfactant) and water. The efficiency of such a process is illustrated with the peroxidation of a poorly reactive substrate, viz., beta-pinene.

Modelling and simulation of fuel cell dynamics for electrical energy usage of Hercules airplanes.

PubMed

Radmanesh, Hamid; Heidari Yazdi, Seyed Saeid; Gharehpetian, G B; Fathi, S H

2014-01-01

Dynamics of proton exchange membrane fuel cells (PEMFC) with hydrogen storage system for generating part of Hercules airplanes electrical energy is presented. Feasibility of using fuel cell (FC) for this airplane is evaluated by means of simulations. Temperature change and dual layer capacity effect are considered in all simulations. Using a three-level 3-phase inverter, FC's output voltage is connected to the essential bus of the airplane. Moreover, it is possible to connect FC's output voltage to airplane DC bus alternatively. PID controller is presented to control flow of hydrogen and oxygen to FC and improve transient and steady state responses of the output voltage to load disturbances. FC's output voltage is regulated via an ultracapacitor. Simulations are carried out via MATLAB/SIMULINK and results show that the load tracking and output voltage regulation are acceptable. The proposed system utilizes an electrolyser to generate hydrogen and a tank for storage. Therefore, there is no need for batteries. Moreover, the generated oxygen could be used in other applications in airplane.

Modelling and Simulation of Fuel Cell Dynamics for Electrical Energy Usage of Hercules Airplanes

PubMed Central

Radmanesh, Hamid; Heidari Yazdi, Seyed Saeid; Gharehpetian, G. B.; Fathi, S. H.

2014-01-01

Dynamics of proton exchange membrane fuel cells (PEMFC) with hydrogen storage system for generating part of Hercules airplanes electrical energy is presented. Feasibility of using fuel cell (FC) for this airplane is evaluated by means of simulations. Temperature change and dual layer capacity effect are considered in all simulations. Using a three-level 3-phase inverter, FC's output voltage is connected to the essential bus of the airplane. Moreover, it is possible to connect FC's output voltage to airplane DC bus alternatively. PID controller is presented to control flow of hydrogen and oxygen to FC and improve transient and steady state responses of the output voltage to load disturbances. FC's output voltage is regulated via an ultracapacitor. Simulations are carried out via MATLAB/SIMULINK and results show that the load tracking and output voltage regulation are acceptable. The proposed system utilizes an electrolyser to generate hydrogen and a tank for storage. Therefore, there is no need for batteries. Moreover, the generated oxygen could be used in other applications in airplane. PMID:24782664

Oxygen-hydrogen torch is a small-scale steam generator

NASA Technical Reports Server (NTRS)

Maskell, C. E.

1966-01-01

Standard oxygen-hydrogen torch generates steam for corrosion-rate analysis of various metals. The steam is generated through local combustion inside a test chamber under constant temperature and pressure control.

Oxygen Partial Pressure Is a Rate-Limiting Parameter for Cell Proliferation in 3D Spheroids Grown in Physioxic Culture Condition

PubMed Central

Gomes, Aurélie; Guillaume, Ludivine; Grimes, David Robert; Fehrenbach, Jérôme; Lobjois, Valérie; Ducommun, Bernard

2016-01-01

The in situ oxygen partial pressure in normal and tumor tissues is in the range of a few percent. Therefore, when studying cell growth in 3D culture systems, it is essential to consider how the physiological oxygen concentration, rather than the one in the ambient air, influences the proliferation parameters. Here, we investigated the effect of reducing oxygen partial pressure from 21% to 5% on cell proliferation rate and regionalization in a 3D tumor spheroid model. We found that 5% oxygen concentration strongly inhibited spheroid growth, changed the proliferation gradient and reduced the 50% In Depth Proliferation index (IDP50), compared with culture at 21% oxygen. We then modeled the oxygen partial pressure profiles using the experimental data generated by culturing spheroids in physioxic and normoxic conditions. Although hypoxia occurred at similar depth in spheroids grown in the two conditions, oxygen partial pressure was a major rate-limiting factor with a critical effect on cell proliferation rate and regionalization only in spheroids grown in physioxic condition and not in spheroids grown at atmospheric normoxia. Our findings strengthen the need to consider conducting experiment in physioxic conditions (i.e., tissue normoxia) for proper understanding of cancer cell biology and the evaluation of anticancer drugs in 3D culture systems. PMID:27575790

Krikalev with failed Elektron Liquid Unit #6 (BZh-6)

NASA Image and Video Library

2005-06-09

ISS011-E-08465 (9 June 2005) --- Cosmonaut Sergei K. Krikalev, Expedition 11 commander representing Russia's Federal Space Agency, works on the Elektron oxygen-generation system in the Zvezda Service Module on the International Space Station (ISS).

Temperature-sensitive PSII: a novel approach for sustained photosynthetic hydrogen production.

PubMed

Bayro-Kaiser, Vinzenz; Nelson, Nathan

2016-12-01

The need for energy and the associated burden are ever growing. It is crucial to develop new technologies for generating clean and efficient energy for society to avoid upcoming energetic and environmental crises. Sunlight is the most abundant source of energy on the planet. Consequently, it has captured our interest. Certain microalgae possess the ability to capture solar energy and transfer it to the energy carrier, H 2 . H 2 is a valuable fuel, because its combustion produces only one by-product: water. However, the establishment of an efficient biophotolytic H 2 production system is hindered by three main obstacles: (1) the hydrogen-evolving enzyme, [FeFe]-hydrogenase, is highly sensitive to oxygen; (2) energy conversion efficiencies are not economically viable; and (3) hydrogen-producing organisms are sensitive to stressful conditions in large-scale production systems. This study aimed to circumvent the oxygen sensitivity of this process with a cyclic hydrogen production system. This approach required a mutant that responded to high temperatures by reducing oxygen evolution. To that end, we randomly mutagenized the green microalgae, Chlamydomonas reinhardtii, to generate mutants that exhibited temperature-sensitive photoautotrophic growth. The selected mutants were further characterized by their ability to evolve oxygen and hydrogen at 25 and 37 °C. We identified four candidate mutants for this project. We characterized these mutants with PSII fluorescence, P700 absorbance, and immunoblotting analyses. Finally, we demonstrated that these mutants could function in a prototype hydrogen-producing bioreactor. These mutant microalgae represent a novel approach for sustained hydrogen production.

Effect of oxygen on the per‐cell extracellular electron transfer rate of Shewanella oneidensis MR‐1 explored in bioelectrochemical systems

PubMed Central

Lu, Mengqian; Chan, Shirley; Babanova, Sofia

2016-01-01

ABSTRACT Extracellular electron transfer (EET) is a mechanism that enables microbes to respire solid‐phase electron acceptors. These EET reactions most often occur in the absence of oxygen, since oxygen can act as a competitive electron acceptor for many facultative microbes. However, for Shewanella oneidensis MR‐1, oxygen may increase biomass development, which could result in an overall increase in EET activity. Here, we studied the effect of oxygen on S. oneidensis MR‐1 EET rates using bioelectrochemical systems (BESs). We utilized optically accessible BESs to monitor real‐time biomass growth, and studied the per‐cell EET rate as a function of oxygen and riboflavin concentrations in BESs of different design and operational conditions. Our results show that oxygen exposure promotes biomass development on the electrode, but significantly impairs per‐cell EET rates even though current production does not always decrease with oxygen exposure. Additionally, our results indicated that oxygen can affect the role of riboflavin in EET. Under anaerobic conditions, both current density and per‐cell EET rate increase with the riboflavin concentration. However, as the dissolved oxygen (DO) value increased to 0.42 mg/L, riboflavin showed very limited enhancement on per‐cell EET rate and current generation. Since it is known that oxygen can promote flavins secretion in S. oneidensis, the role of riboflavin may change under anaerobic and aerobic conditions. Biotechnol. Bioeng. 2017;114: 96–105. © 2016 The Authors. Biotechnology and Bioengineering Published by Wiley Periodicals, Inc. PMID:27399911

Lightside Atmospheric Revitalization System

NASA Technical Reports Server (NTRS)

Colling, A. K.; Cushman, R. J.; Hultman, M. M.; Nason, J. R.

1980-01-01

The system was studied as a replacement to the present baseline LiOH system for extended duration shuttle missions. The system consists of three subsystems: a solid amine water desorbed regenerable carbon dioxide removal system, a water vapor electrolysis oxygen generating system, and a Sabatier reactor carbon dioxide reduction system. The system is designed for use on a solar powered shuttle vehicle. The majority of the system's power requirements are utilized on the Sun side of each orbit, when solar power is available.

Oxygen Generation from Carbon Dioxide for Advanced Life Support

NASA Technical Reports Server (NTRS)

Bishop, s. R.; Duncan, K. L.; Hagelin-Weaver, H. E.; Neal, L.; Paul, H. L.; Wachsman, E. D.

2007-01-01

The partial electrochemical reduction of CO2 using ceramic oxygen generators (COGs) is well known and has been studied. Conventional COGs use yttria-stabilized zirconia (YSZ) electrolytes and operate at temperatures greater than 700 C (1, 2). Operating at a lower temperature has the advantage of reducing the mass of the ancillary components such as insulation. Moreover, complete reduction of metabolically produced CO2 (into carbon and oxygen) has the potential of reducing oxygen storage weight if the oxygen can be recovered. Recently, the University of Florida developed ceramic oxygen generators employing a bilayer electrolyte of gadolinia-doped ceria and erbia-stabilized bismuth oxide (ESB) for NASA s future exploration of Mars (3). The results showed that oxygen could be reliably produced from CO2 at temperatures as low as 400 C. These results indicate that this technology could be adapted to CO2 removal from a spacesuit and other applications in which CO2 removal is an issue. This strategy for CO2 removal in advanced life support systems employs a catalytic layer combined with a COG so that the CO2 is reduced completely to solid carbon and oxygen. First, to reduce the COG operating temperature, a thin, bilayer electrolyte was employed. Second, to promote full CO2 reduction while avoiding the problem of carbon deposition on the COG cathode, a catalytic carbon deposition layer was designed and the cathode utilized materials shown to be coke resistant. Third, a composite anode was used consisting of bismuth ruthenate (BRO) and ESB that has been shown to have high performance (4). The inset of figure 1 shows the conceptual design of the tubular COG and the rest of the figure shows schematically the test apparatus. Figure 2 shows the microstructure of a COG tube prior to testing. During testing, current is applied across the cell and initially CuO is reduced to copper metal by electrochemical pumping. Then the oxygen source becomes the CO/CO2. This presentation details the results of testing the COG.

Mixed ionic and electronic conducting membranes for hydrogen generation and separation

NASA Astrophysics Data System (ADS)

Cui, Hengdong

Dense mixed ionic and electronic conducting (MIEC) membranes are receiving increasing attention due to their potential for application as gas separation membranes to separate oxygen from air. The objective of this work is to study a novel, chemically-assisted separation process that utilizes oxygen-ion and electron-conducting MIECs for generating and separating hydrogen from steam. This research aims at exploring new routes and materials for high-purity hydrogen production for use in fuel cells and hydrogen-based internal combustion (IC) engines. In this approach, hydrocarbon fuel such as methane is fed to one side of the membrane, while steam is fed to the other side. The MIEC membrane separation process involves steam dissociation and oxidation of the fuel. The oxygen ions formed as a result of steam dissociation are transported across the membrane in a coupled transport process with electrons being transported in the opposite direction. Upon reaching the fuel side of the membrane, the oxygen ions oxidize the hydrocarbon. This process results in hydrogen production on the steam side of the membrane. The oxygen partial pressure gradient across the membrane is the driving force for this process. In this work, a novel, dual-phase composite MIEC membrane system comprising of rare-earth doped ceria with high oxygen ion conductivity and donor-doped strontium titanate with high electronic conductivity were investigated. The chemical diffusion coefficient and surface exchange coefficient have been measured using the electrical conductivity relaxation (ECR) technique. These two parameters control the rate of oxygen permeation across the membrane. The permeation data have been fit with a kinetic model that incorporates oxygen surface exchange on two sides of the membrane and bulk transport of oxygen through the membrane. This material has higher bulk diffusion coefficient and surface exchange reaction rate compared to other known MIEC conductors under the process conditions of interest. Over 10 mumol·cm-2·s-1 (micromoles per square cm per second) of area specific hydrogen flux has been achieved employing a membrane of this material with thickness of 0.2 mm. This flux is several orders of magnitude higher than the hydrogen generation rates reported using other MIEC materials under similar operating conditions.

Topical oxygen therapy & micro/nanobubbles: a new modality for tissue oxygen delivery.

PubMed

Sayadi, Lohrasb R; Banyard, Derek A; Ziegler, Mary E; Obagi, Zaidal; Prussak, Jordyne; Klopfer, Michael J; Evans, Gregory Rd; Widgerow, Alan D

2018-06-01

Up to 15 billion dollars of US health care expenditure each year is consumed by treatment of poorly healing wounds whose etiologies are often associated with aberrancies in tissue oxygenation. To address this issue, several modes of tissue oxygen delivery systems exist, including Hyperbaric Oxygen Therapy (HBOT) and Topical Oxygen Therapy (TOT), but their efficacies have yet to be fully substantiated. Micro/nanobubbles (MNBs), which range anywhere from 100 μm to <1 μm in diameter and are relatively stable for hours, offer a new mode of oxygen delivery to wounds. The aim of this article is to systematically review literature examining the use of TOT for wound healing and use of MNBs for tissue oxygenation using the MEDLINE database. The search yielded 87 articles (12 MNB articles and 75 TOT articles), of which 52 met the inclusion criteria for this literature review (12 MNB articles and 40 TOT articles). Additionally, we present an analysis on the efficacy of our MNB generating technology and propose its use as a wound healing agent. © 2018 Medicalhelplines.com Inc and John Wiley & Sons Ltd.

Enhanced Lithium Oxygen Battery Using a Glyme Electrolyte and Carbon Nanotubes.

PubMed

Carbone, Lorenzo; Moro, Paolo Tomislav; Gobet, Mallory; Munoz, Stephen; Devany, Matthew; Greenbaum, Steven G; Hassoun, Jusef

2018-05-16

The lithium oxygen battery has a theoretical energy density potentially meeting the challenging requirements of electric vehicles. However, safety concerns and short lifespan hinder its application in practical systems. In this work, we show a cell configuration, including a multiwalled carbon nanotube electrode and a low flammability glyme electrolyte, capable of hundreds of cycles without signs of decay. Nuclear magnetic resonance and electrochemical tests confirm the suitability of the electrolyte in a practical battery, whereas morphological and structural aspects revealed by electron microscopy and X-ray diffraction demonstrate the reversible formation and dissolution of lithium peroxide during the electrochemical process. The enhanced cycle life of the cell and the high safety of the electrolyte suggest the lithium oxygen battery herein reported as a viable system for the next generation of high-energy applications.

Photosensitized singlet oxygen generation and detection: Recent advances and future perspectives in cancer photodynamic therapy.

PubMed

Li, Buhong; Lin, Lisheng; Lin, Huiyun; Wilson, Brian C

2016-12-01

Photodynamic therapy (PDT) uses photosensitizers and visible light in combination with molecular oxygen to produce reactive oxygen species (ROS) that kill malignant cells by apoptosis and/or necrosis, shut down the tumor microvasculature and stimulate the host immune system. The excited singlet state of oxygen ( 1 O 2 ) is recognized to be the main cytotoxic ROS generated during PDT for the majority of photosensitizers used clinically and for many investigational new agents, so that maximizing its production within tumor cells and tissues can improve the therapeutic response, and several emerging and novel approaches for this are summarized. Quantitative techniques for 1 O 2 production measurement during photosensitization are also of immense importance of value for both preclinical research and future clinical practice. In this review, emerging strategies for enhanced photosensitized 1 O 2 generation are introduced, while recent advances in direct detection and imaging of 1 O 2 luminescence are summarized. In addition, the correlation between cumulative 1 O 2 luminescence and PDT efficiency will be highlighted. Meanwhile, the validation of 1 O 2 luminescence dosimetry for PDT application is also considered. This review concludes with a discussion on future demands of 1 O 2 luminescence detection for PDT dosimetry, with particular emphasis on clinical translation. Eye-catching color image for graphical abstract. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Minuteman III Motor-Generator Bearing Grease Replacement

DTIC Science & Technology

2013-07-01

Biodegradation is a natural process caused by the action of microorganisms in the presence of oxygen, nitrogen, phosphorous, and trace minerals. Organic... biodegradable are considered less toxic and more environmentally friendly. Currently, this technology has been mandated in order to reduce the ...AFB2 grease and Capella WF-68 oil currently used in the MINUTEMAN III Motor-generator (M-G) Bearing Systems. Due to the unavailability

ACES: An Enabling Technology for Next Generation Space Transportation

NASA Astrophysics Data System (ADS)

Crocker, Andrew M.; Wuerl, Adam M.; Andrews, Jason E.; Andrews, Dana G.

2004-02-01

Andrews Space has developed the ``Alchemist'' Air Collection and Enrichment System (ACES), a dual-mode propulsion system that enables safe, economical launch systems that take off and land horizontally. Alchemist generates liquid oxygen through separation of atmospheric air using the refrigeration capacity of liquid hydrogen. The key benefit of Alchemist is that it minimizes vehicle takeoff weight. All internal and NASA-funded activities have shown that ACES, previously proposed for hypersonic combined cycle RLVs, is a higher payoff, lower-risk technology if LOX generation is performed while the vehicle cruises subsonically. Andrews Space has developed the Alchemist concept from a small system study to viable Next Generation launch system technology, conducting not only feasibility studies but also related hardware tests, and it has planned a detailed risk reduction program which employs an experienced, proven contractor team. Andrews also has participated in preliminary studies of an evolvable Next Generation vehicle architecture-enabled by Alchemist ACES-which could meet civil, military, and commercial space requirements within two decades.

Effects of peptides on generation of reactive oxygen species in subcellular fractions of Drosophila melanogaster.

PubMed

Khavinson, V K; Myl'nikov, S V; Oparina, T I; Arutyunyan, A V

2001-07-01

We studied the effects of Epithalon (Ala-Glu-Asp-Gly) and Vilon (Lys-Glu) on free radical processes in highly inbred HA(+)line of Drosophila melanogaster. Vilon inhibited generation of reactive oxygen species in mitochondria, but stimulated this process in the cytosol. We found sex- and age-related differences in the generation of reactive oxygen species and cytosol antioxidant activity.

Electricity generation in a membrane-less microbial fuel cell with down-flow feeding onto the cathode.

PubMed

Zhu, Feng; Wang, Wancheng; Zhang, Xiaoyan; Tao, Guanhong

2011-08-01

A novel membrane-less microbial fuel cell (MFC) with down-flow feeding was constructed to generate electricity. Wastewater was fed directly onto the cathode which was horizontally installed in the upper part of the MFC. Oxygen could be utilized readily from the air. The concentration of dissolved oxygen in the influent wastewater had little effect on the power generation. A saturation-type relationship was observed between the initial COD and the power generation. The influent flow rate could affect greatly the power density. Fed by the synthetic glucose wastewater with a COD value of 3500 mg/L at a flow rate of 4.0 mL/min, the developed MFC could produce a maximum power density of 37.4 mW/m(2). Its applicability was further evaluated by the treatment of brewery wastewater. The system could be scaled up readily due to its simple configuration, easy operation and relatively high power density. Copyright © 2011 Elsevier Ltd. All rights reserved.

Responses of Solid Tumor Cells in DMEM to Reactive Oxygen Species Generated by Non-Thermal Plasma and Chemically Induced ROS Systems

PubMed Central

Kaushik, Neha; Uddin, Nizam; Sim, Geon Bo; Hong, Young June; Baik, Ku Youn; Kim, Chung Hyeok; Lee, Su Jae; Kaushik, Nagendra Kumar; Choi, Eun Ha

2015-01-01

In this study, we assessed the role of different reactive oxygen species (ROS) generated by soft jet plasma and chemical-induced ROS systems with regard to cell death in T98G, A549, HEK293 and MRC5 cell lines. For a comparison with plasma, we generated superoxide anion (O2−), hydroxyl radical (HO·), and hydrogen peroxide (H2O2) with chemicals inside an in vitro cell culture. Our data revealed that plasma decreased the viability and intracellular ATP values of cells and increased the apoptotic population via a caspase activation mechanism. Plasma altered the mitochondrial membrane potential and eventually up-regulated the mRNA expression levels of BAX, BAK1 and H2AX gene but simultaneously down-regulated the levels of Bcl-2 in solid tumor cells. Moreover, a western blot analysis confirmed that plasma also altered phosphorylated ERK1/2/MAPK protein levels. At the same time, using ROS scavengers with plasma, we observed that scavengers of HO· (mannitol) and H2O2 (catalase and sodium pyruvate) attenuated the activity of plasma on cells to a large extent. In contrast, radicals generated by specific chemical systems enhanced cell death drastically in cancer as well as normal cell lines in a dose-dependent fashion but not specific with regard to the cell type as compared to plasma. PMID:25715710

Responses of Solid Tumor Cells in DMEM to Reactive Oxygen Species Generated by Non-Thermal Plasma and Chemically Induced ROS Systems

NASA Astrophysics Data System (ADS)

Kaushik, Neha; Uddin, Nizam; Sim, Geon Bo; Hong, Young June; Baik, Ku Youn; Kim, Chung Hyeok; Lee, Su Jae; Kaushik, Nagendra Kumar; Choi, Eun Ha

2015-02-01

In this study, we assessed the role of different reactive oxygen species (ROS) generated by soft jet plasma and chemical-induced ROS systems with regard to cell death in T98G, A549, HEK293 and MRC5 cell lines. For a comparison with plasma, we generated superoxide anion (O2-), hydroxyl radical (HO.), and hydrogen peroxide (H2O2) with chemicals inside an in vitro cell culture. Our data revealed that plasma decreased the viability and intracellular ATP values of cells and increased the apoptotic population via a caspase activation mechanism. Plasma altered the mitochondrial membrane potential and eventually up-regulated the mRNA expression levels of BAX, BAK1 and H2AX gene but simultaneously down-regulated the levels of Bcl-2 in solid tumor cells. Moreover, a western blot analysis confirmed that plasma also altered phosphorylated ERK1/2/MAPK protein levels. At the same time, using ROS scavengers with plasma, we observed that scavengers of HO. (mannitol) and H2O2 (catalase and sodium pyruvate) attenuated the activity of plasma on cells to a large extent. In contrast, radicals generated by specific chemical systems enhanced cell death drastically in cancer as well as normal cell lines in a dose-dependent fashion but not specific with regard to the cell type as compared to plasma.

Hydrogen-Enhanced Lunar Oxygen Extraction and Storage Using Only Solar Power

NASA Technical Reports Server (NTRS)

Burton, rodney; King, Darren

2013-01-01

The innovation consists of a thermodynamic system for extracting in situ oxygen vapor from lunar regolith using a solar photovoltaic power source in a reactor, a method for thermally insulating the reactor, a method for protecting the reactor internal components from oxidation by the extracted oxygen, a method for removing unwanted chemical species produced in the reactor from the oxygen vapor, a method for passively storing the oxygen, and a method for releasing high-purity oxygen from storage for lunar use. Lunar oxygen exists in various types of minerals, mostly silicates. The energy required to extract the oxygen from the minerals is 30 to 60 MJ/kg O. Using simple heating, the extraction rate depends on temperature. The minimum temperature is approximately 2,500 K, which is at the upper end of available oven temperatures. The oxygen is released from storage in a purified state, as needed, especially if for human consumption. This method extracts oxygen from regolith by treating the problem as a closed batch cycle system. The innovation works equally well in Earth or Lunar gravity fields, at low partial pressure of oxygen, and makes use of in situ regolith for system insulation. The innovation extracts oxygen from lunar regolith using a method similar to vacuum pyrolysis, but with hydrogen cover gas added stoichiometrically to react with the oxygen as it is produced by radiatively heating regolith to 2,500 K. The hydrogen flows over and through the heating element (HE), protecting it from released oxygen. The H2 O2 heat of reaction is regeneratively recovered to assist the heating process. Lunar regolith is loaded into a large-diameter, low-height pancake reactor powered by photovoltaic cells. The reactor lid contains a 2,500 K HE that radiates downward onto the regolith to heat it and extract oxygen, and is shielded above by a multi-layer tungsten radiation shield. Hydrogen cover gas percolates through the perforated tungsten shielding and HE, preventing oxidation of the shielding and HE, and reacting with the oxygen to form water vapor. The water vapor is filtered through solid regolith to remove unwanted extraction byproducts, and then condensed to a liquid state and stored at 300 to 325 K. Conversion to usable oxygen is achieved by pumping liquid water into a high-pressure electrolyzer, storing the gaseous oxygen at high pressure for use, and diverting the hydrogen back to the reactor or to storage. The results from this design effort show that this oxygen-generating concept can be developed in an efficient system with low specific mass. Advantages include use of regolith as an oxygen source, filter, and thermal insulator. The system can be tested in Earth gravity and can be expected to operate similarly in lunar gravity. The system is scalable, either by increasing the power level and output of a standard module, or by employing multiple modules.

New insight into singlet oxygen generation at surface modified nanocrystalline TiO2--the effect of near-infrared irradiation.

PubMed

Buchalska, Marta; Labuz, Przemysław; Bujak, Łukasz; Szewczyk, Grzegorz; Sarna, Tadeusz; Maćkowski, Sebastian; Macyk, Wojciech

2013-07-14

The generation of singlet oxygen in aqueous colloids of nanocrystalline TiO2 (anatase) modified by organic chelating ligands forming surface Ti(IV) complexes was studied. Detailed studies revealed a plausible and to date unappreciated influence of near-infrared irradiation on singlet oxygen generation at the surface of TiO2. To detect (1)O2, direct and indirect methods have been applied: a photon counting technique enabling time-resolved measurements of (1)O2 phosphorescence, and fluorescence measurements of a product of singlet oxygen interaction with Singlet Oxygen Sensor Green (SOSG). Both methods proved the generation of (1)O2. Nanocrystalline TiO2 modified with salicylic acid appeared to be the most efficient photosensitizer among the tested materials. The measured quantum yield reached the value of 0.012 upon irradiation at 355 nm, while unmodified TiO2 colloids appeared to be substantially less efficient generators of singlet oxygen with the corresponding quantum yield of ca. 0.003. A photocatalytic degradation of 4-chlorophenol, proceeding through oxidation by OH˙, was also monitored. The influence of irradiation conditions (UV, vis, NIR or any combination of these spectral ranges) on the generation of both singlet oxygen and hydroxyl radicals has been tested and discussed. Simultaneous irradiation with visible and NIR light did not accelerate OH˙ formation; however, for TiO2 modified with catechol it influenced (1)O2 generation. Singlet oxygen is presumably formed according to Nosaka's mechanism comprising O2˙(-) oxidation with a strong oxidant (hole, an oxidized ligand); however, the energy transfer from NIR-excited titanium(iii) centers (trapped electrons) plays also a plausible role.

Fabrication and Performance of Zirconia Electrolysis Cells for Carbon Dioxide Reduction for Mars In Situ Resource Utilization Applications

NASA Technical Reports Server (NTRS)

Minh, N. Q.; Chung, B. W.; Doshi, R.; Lear, G. R.; Montgomery, K.; Ong, E. T.

1999-01-01

The use of the Martian atmosphere (95% CO2) to produce oxygen (for propellant and life support) can significantly lower the required launch mass and dramatically reduce the total cost for Mars missions. Zirconia electrolysis cells are one of the technologies being considered for oxygen generation from carbon dioxide in Mars In Situ Resource Utilization (ISRU) production plants. The attractive features of the zirconia cell for this application include simple operation and lightweight, low volume system.

Catalysts for electrochemical generation of oxygen

NASA Technical Reports Server (NTRS)

Hagans, P.; Yeager, E.

1979-01-01

Several aspects of the electrolytic evolution of oxygen for use in life support systems are analyzed including kinetic studies of various metal and nonmetal electrode materials, the formation of underpotential films on electrodes, and electrode surface morphology and the use of single crystal metals. In order to investigate the role of surface morphology to electrochemical reactions, a low energy electron diffraction and an Auger electron spectrometer are combined with an electrochemical thin-layer cell allowing initial characterization of the surface, reaction run, and then a comparative surface analysis.

Human Factors Process Task Analysis: Liquid Oxygen Pump Acceptance Test Procedure at the Advanced Technology Development Center

NASA Technical Reports Server (NTRS)

Diorio, Kimberly A.; Voska, Ned (Technical Monitor)

2002-01-01

This viewgraph presentation provides information on Human Factors Process Failure Modes and Effects Analysis (HF PFMEA). HF PFMEA includes the following 10 steps: Describe mission; Define System; Identify human-machine; List human actions; Identify potential errors; Identify factors that effect error; Determine likelihood of error; Determine potential effects of errors; Evaluate risk; Generate solutions (manage error). The presentation also describes how this analysis was applied to a liquid oxygen pump acceptance test.

Reactive Oxygen Species and Inhibitors of Inflammatory Enzymes, NADPH Oxidase, and iNOS in Experimental Models of Parkinson's Disease

PubMed Central

Koppula, Sushruta; Kumar, Hemant; Kim, In Su; Choi, Dong-Kug

2012-01-01

Reactive oxygen species (ROSs) are emerging as important players in the etiology of neurodegenerative disorders including Parkinson's disease (PD). Out of several ROS-generating systems, the inflammatory enzymes nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and inducible nitric oxide synthase (iNOS) were believed to play major roles. Mounting evidence suggests that activation of NADPH oxidase and the expression of iNOS are directly linked to the generation of highly reactive ROS which affects various cellular components and preferentially damage midbrain dopaminergic neurons in PD. Therefore, appropriate management or inhibition of ROS generated by these enzymes may represent a therapeutic target to reduce neuronal degeneration seen in PD. Here, we have summarized recently developed agents and patents claimed as inhibitors of NADPH oxidase and iNOS enzymes in experimental models of PD. PMID:22577256

In situ measurements of dissolved oxygen, pH and redox potential of biocathode microenvironments using microelectrodes.

PubMed

Wang, Zejie; Deng, Huan; Chen, Lihui; Xiao, Yong; Zhao, Feng

2013-03-01

Biofilms are the core component of bioelectrochemical systems (BESs). To understand the polarization effects on biocathode performance of BES, dissolved oxygen concentrations, pHs and oxidation-reduction potentials of biofilm microenvironments were determined in situ. The results showed that lower polarization potentials resulted in the generation of larger currents and higher pH values, as well as the consumption of more oxygen. Oxidation-reduction potentials of biofilms were mainly affected by polarization potentials of the electrode rather than the concentration of dissolved oxygen or pH value, and its changes in the potentials corresponded to the electric field distribution of the electrode surface. The results demonstrated that a sufficient supply of dissolved oxygen and pH control of the biocathode are necessary to obtain optimal performance of BESs; a lower polarization potential endowed microorganisms with a higher electrochemical activity. Copyright © 2012 Elsevier Ltd. All rights reserved.

Cytotoxic and Antitumor Activity of Sulforaphane: The Role of Reactive Oxygen Species

PubMed Central

Sestili, Piero

2015-01-01

According to recent estimates, cancer continues to remain the second leading cause of death and is becoming the leading one in old age. Failure and high systemic toxicity of conventional cancer therapies have accelerated the identification and development of innovative preventive as well as therapeutic strategies to contrast cancer-associated morbidity and mortality. In recent years, increasing body of in vitro and in vivo studies has underscored the cancer preventive and therapeutic efficacy of the isothiocyanate sulforaphane. In this review article, we highlight that sulforaphane cytotoxicity derives from complex, concurring, and multiple mechanisms, among which the generation of reactive oxygen species has been identified as playing a central role in promoting apoptosis and autophagy of target cells. We also discuss the site and the mechanism of reactive oxygen species' formation by sulforaphane, the toxicological relevance of sulforaphane-formed reactive oxygen species, and the death pathways triggered by sulforaphane-derived reactive oxygen species. PMID:26185755

Enhanced spin–orbit torques by oxygen incorporation in tungsten films

PubMed Central

Demasius, Kai-Uwe; Phung, Timothy; Zhang, Weifeng; Hughes, Brian P.; Yang, See-Hun; Kellock, Andrew; Han, Wei; Pushp, Aakash; Parkin, Stuart S. P.

2016-01-01

The origin of spin–orbit torques, which are generated by the conversion of charge-to-spin currents in non-magnetic materials, is of considerable debate. One of the most interesting materials is tungsten, for which large spin–orbit torques have been found in thin films that are stabilized in the A15 (β-phase) structure. Here we report large spin Hall angles of up to approximately –0.5 by incorporating oxygen into tungsten. While the incorporation of oxygen into the tungsten films leads to significant changes in their microstructure and electrical resistivity, the large spin Hall angles measured are found to be remarkably insensitive to the oxygen-doping level (12–44%). The invariance of the spin Hall angle for higher oxygen concentrations with the bulk properties of the films suggests that the spin–orbit torques in this system may originate dominantly from the interface rather than from the interior of the films. PMID:26912203

Micro-Encapsulated Porphyrins and Phthalocyanines - New Formulations in Photodynamic Therapy

NASA Astrophysics Data System (ADS)

Ion, R. M.

2017-06-01

Photodynamic therapy (PDT), as an innovative method for cancer tretament is based on a concerted action of some drugs, called sensitizers, which generate reactive oxygen species via a photochemical mechanism, leading to cellular necrosis or apoptosis. The present work aims at loading some sensitizers, as porphyrins (P) and phthalocyanines (Pc) into alginate particles. Particles were prepared by dropping alginate into an aqueous solution containing P or Pc and CaCl2, which allows the formation of particles through ionic crosslinking. It was obtained P or Pc loaded alginate beads with an average diameter of about 100 μm. For these systems, this paper analyses the spectroscopic properties, encapsulation into microcapsules, controlled releasing action and their photosensitizer capacity (singlet oxygen generation).

The structural and electrical evolution of graphene by oxygen plasma-induced disorder.

PubMed

Kim, Dong Chul; Jeon, Dae-Young; Chung, Hyun-Jong; Woo, YunSung; Shin, Jai Kwang; Seo, Sunae

2009-09-16

Evolution of a single graphene layer with disorder generated by remote oxygen plasma irradiation is investigated using atomic force microscopy, Raman spectroscopy and electrical measurement. Gradual changes of surface morphology from planar graphene to isolated granular structure associated with a decrease of transconductance are accounted for by two-dimensional percolative conduction by disorder and the oxygen plasma-induced doping effect. The corresponding evolution of Raman spectra of graphene shows several peculiarities such as a sudden appearance of a saturated D peak followed by a linear decrease in its intensity, a relatively inert characteristic of a D' peak and a monotonic increase of a G peak position as the exposure time to oxygen plasma increases. These are discussed in terms of a disorder-induced change of Raman spectra in the graphite system.

Singlet-Oxygen Generation From Individual Semiconducting and Metallic Nanostructures During Near-Infrared Laser Trapping

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

Smith, Bennett E.; Roder, Paden B.; Hanson, Jennifer L.

2015-03-13

Photodynamic therapy has been used for several decades in the treatment of solid tumors through the generation of reactive singlet-oxygen species (1O2). Recently, nanoscale metallic and semiconducting materials have been reported to act as photosensitizing agents with additional diagnostic and therapeutic functionality. To date there have been no reports of observing the generation of singlet-oxygen at the level of single nanostructures, particularly at near infrared (NIR) wavelengths. Here we demonstrate that NIR laser-tweezers can be used to observe the formation of singlet-oxygen produced from individual silicon and gold nanowires via use of a commercially available reporting dye. The laser trapmore » also induces 2-photon photoexcitation of the dye following a chemical reaction with singlet oxygen. Corresponding 2-photon emission spectra confirms the generation of singlet oxygen from individual silicon nanowires at room temperature (30°C), suggesting a range of applications in understanding the impact of 1O2 on individual cancer cells.« less

Singlet Delta oxygen generation for chemical oxygen-iodine lasers

NASA Astrophysics Data System (ADS)

Georges, E.; Mouthon, A.; Barraud, R.

To improve the overall efficiency of chemical oxygen-iodine lasers, it is necessary to increase the generator production and yield of singlet delta oxygen at low and high pressure, respectively, for subsonic and supersonic lasers. The water vapor content must also be as low as possible. A generator model based on gas-liquid reaction and liquid-vapor equilibrium theories is presented. From model predictions, operating conditions have been drawn to attain the following experimental results in a bubble-column: by increasing the superficial gas velocity, the production of singlet delta oxygen is largely improved at low pressure; by mixing chlorine with an inert gas before injection in the reactor, this yield is maintained constant up to higher pressure.

Reactive oxygen species: players in the cardiovascular effects of testosterone

PubMed Central

Carneiro, Fernando S.; Carvalho, Maria Helena C.; Reckelhoff, Jane F.

2015-01-01

Androgens are essential for the development and maintenance of male reproductive tissues and sexual function and for overall health and well being. Testosterone, the predominant and most important androgen, not only affects the male reproductive system, but also influences the activity of many other organs. In the cardiovascular system, the actions of testosterone are still controversial, its effects ranging from protective to deleterious. While early studies showed that testosterone replacement therapy exerted beneficial effects on cardiovascular disease, some recent safety studies point to a positive association between endogenous and supraphysiological levels of androgens/testosterone and cardiovascular disease risk. Among the possible mechanisms involved in the actions of testosterone on the cardiovascular system, indirect actions (changes in the lipid profile, insulin sensitivity, and hemostatic mechanisms, modulation of the sympathetic nervous system and renin-angiotensin-aldosterone system), as well as direct actions (modulatory effects on proinflammatory enzymes, on the generation of reactive oxygen species, nitric oxide bioavailability, and on vasoconstrictor signaling pathways) have been reported. This mini-review focuses on evidence indicating that testosterone has prooxidative actions that may contribute to its deleterious actions in the cardiovascular system. The controversial effects of testosterone on ROS generation and oxidant status, both prooxidant and antioxidant, in the cardiovascular system and in cells and tissues of other systems are reviewed. PMID:26538238

FiO2 delivered by a turbine portable ventilator with an oxygen concentrator in an Austere environment.

PubMed

Bordes, Julien; Erwan d'Aranda; Savoie, Pierre-Henry; Montcriol, Ambroise; Goutorbe, Philippe; Kaiser, Eric

2014-09-01

Management of critically ill patients in austere environments is a logistic challenge. Availability of oxygen cylinders for the mechanically ventilated patient may be difficult in such a context. A solution is to use a ventilator able to function with an oxygen concentrator. We tested the SeQual Integra™ (SeQual, San Diego, CA) 10-OM oxygen concentrator paired with the Pulmonetic System(®) LTV 1000 ventilator (Pulmonetic Systems, Minneapolis, MN) and evaluated the delivered fraction of inspired oxygen (FiO2) across a range of minute volumes and combinations of ventilator settings. Two LTV 1000 ventilators were tested. The ventilators were attached to a test lung and FiO2 was measured by a gas analyzer. Continuous-flow oxygen was generated by the OC from 0.5 L/min to 10 L/min and injected into the oxygen inlet port of the LTV 1000. Several combinations of ventilator settings were evaluated to determine the factors affecting the delivered FiO2. The LTV 1000 ventilator is a turbine ventilator that is able to deliver high FiO2 when functioning with an oxygen concentrator. However, modifications of the ventilator settings such as increase in minute ventilation affect delivered FiO2 even if oxygen flow is constant on the oxygen concentrator. The ability of an oxygen concentrator to deliver high FiO2 when used with a turbine ventilator makes this method of oxygen delivery a viable alternative to cylinders in austere environments when used with a turbine ventilator. However, FiO2 has to be monitored continuously because delivered FiO2 decreases when minute ventilation is increased. Copyright © 2014 Elsevier Inc. All rights reserved.

Low NO[sub x], cogeneration process and system

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

Bell, R.D.

1993-07-06

A process is described for low NO[sub x] cogeneration to produce electricity and useful heat, which comprises: providing fuel and oxygen to an internal combustion engine connected to drive an electric generator, to thereby generate electricity; recovering from said engine an exhaust stream including elevated NO[sub x] levels and combined oxygen; adding to said exhaust stream sufficient fuel to create a fuel-rich mixture, the quantity of fuel being sufficient to react with the available oxygen and reduce the NO[sub x], in said exhaust stream; providing said fuel-enriched exhaust stream to a thermal reactor and reacting therein said fuel, NO[sub x]more » and available oxygen, to provide a heated oxygen-depleted stream; cooling said oxygen-depleted stream by passing same through a first heat exchanger; adding conversion oxygen to said cooled stream from said heat exchanger, and passing the cooled oxygen-augmented stream over a first catalyst bed operated at a temperature of about 750 to 1,250 F under overall reducing conditions, the quantity of conversion oxygen added being in stoichiometric excess of the amount of NO[sub x], but less than the amount of combustibles; whereby the NO[sub x] is first oxidized to NO[sub 2], and then the NO[sub 2] is reduced by the excess combustibles; cooling said stream from said first catalyst bed to a temperature of about 450 to 650 F by passing said stream through a second heat exchanger; adding air to the resulting cooled stream to produce a further cooled stream at a temperature of about 400 to 600 F, and having a stoichiometric excess of oxygen; and passing said stream having said stoichiometric excess of oxygen over an oxidizing catalyst bed at said temperature of 400 to 600 F to oxidize remaining excess combustibles, to thereby provide an effluent stream having environmentally safe characteristics.« less

Microsecond-pulsed dielectric barrier discharge plasma stimulation of tissue macrophages for treatment of peripheral vascular disease

PubMed Central

Miller, V.; Lin, A.; Kako, F.; Gabunia, K.; Kelemen, S.; Brettschneider, J.; Fridman, G.; Fridman, A.; Autieri, M.

2015-01-01

Angiogenesis is the formation of new blood vessels from pre-existing vessels and normally occurs during the process of inflammatory reactions, wound healing, tissue repair, and restoration of blood flow after injury or insult. Stimulation of angiogenesis is a promising and an important step in the treatment of peripheral artery disease. Reactive oxygen species have been shown to be involved in stimulation of this process. For this reason, we have developed and validated a non-equilibrium atmospheric temperature and pressure short-pulsed dielectric barrier discharge plasma system, which can non-destructively generate reactive oxygen species and other active species at the surface of the tissue being treated. We show that this plasma treatment stimulates the production of vascular endothelial growth factor, matrix metalloproteinase-9, and CXCL 1 that in turn induces angiogenesis in mouse aortic rings in vitro. This effect may be mediated by the direct effect of plasma generated reactive oxygen species on tissue. PMID:26543345

Microsecond-pulsed dielectric barrier discharge plasma stimulation of tissue macrophages for treatment of peripheral vascular disease

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

Miller, V., E-mail: vmiller@coe.drexel.edu; Lin, A.; Brettschneider, J.

Angiogenesis is the formation of new blood vessels from pre-existing vessels and normally occurs during the process of inflammatory reactions, wound healing, tissue repair, and restoration of blood flow after injury or insult. Stimulation of angiogenesis is a promising and an important step in the treatment of peripheral artery disease. Reactive oxygen species have been shown to be involved in stimulation of this process. For this reason, we have developed and validated a non-equilibrium atmospheric temperature and pressure short-pulsed dielectric barrier discharge plasma system, which can non-destructively generate reactive oxygen species and other active species at the surface of themore » tissue being treated. We show that this plasma treatment stimulates the production of vascular endothelial growth factor, matrix metalloproteinase-9, and CXCL 1 that in turn induces angiogenesis in mouse aortic rings in vitro. This effect may be mediated by the direct effect of plasma generated reactive oxygen species on tissue.« less

Gas-solid interfacial modification of oxygen activity in layered oxide cathodes for lithium-ion batteries.

PubMed

Qiu, Bao; Zhang, Minghao; Wu, Lijun; Wang, Jun; Xia, Yonggao; Qian, Danna; Liu, Haodong; Hy, Sunny; Chen, Yan; An, Ke; Zhu, Yimei; Liu, Zhaoping; Meng, Ying Shirley

2016-07-01

Lattice oxygen can play an intriguing role in electrochemical processes, not only maintaining structural stability, but also influencing electron and ion transport properties in high-capacity oxide cathode materials for Li-ion batteries. Here, we report the design of a gas-solid interface reaction to achieve delicate control of oxygen activity through uniformly creating oxygen vacancies without affecting structural integrity of Li-rich layered oxides. Theoretical calculations and experimental characterizations demonstrate that oxygen vacancies provide a favourable ionic diffusion environment in the bulk and significantly suppress gas release from the surface. The target material is achievable in delivering a discharge capacity as high as 301 mAh g(-1) with initial Coulombic efficiency of 93.2%. After 100 cycles, a reversible capacity of 300 mAh g(-1) still remains without any obvious decay in voltage. This study sheds light on the comprehensive design and control of oxygen activity in transition-metal-oxide systems for next-generation Li-ion batteries.

Gas–solid interfacial modification of oxygen activity in layered oxide cathodes for lithium-ion batteries

PubMed Central

Qiu, Bao; Zhang, Minghao; Wu, Lijun; Wang, Jun; Xia, Yonggao; Qian, Danna; Liu, Haodong; Hy, Sunny; Chen, Yan; An, Ke; Zhu, Yimei; Liu, Zhaoping; Meng, Ying Shirley

2016-01-01

Lattice oxygen can play an intriguing role in electrochemical processes, not only maintaining structural stability, but also influencing electron and ion transport properties in high-capacity oxide cathode materials for Li-ion batteries. Here, we report the design of a gas–solid interface reaction to achieve delicate control of oxygen activity through uniformly creating oxygen vacancies without affecting structural integrity of Li-rich layered oxides. Theoretical calculations and experimental characterizations demonstrate that oxygen vacancies provide a favourable ionic diffusion environment in the bulk and significantly suppress gas release from the surface. The target material is achievable in delivering a discharge capacity as high as 301 mAh g−1 with initial Coulombic efficiency of 93.2%. After 100 cycles, a reversible capacity of 300 mAh g−1 still remains without any obvious decay in voltage. This study sheds light on the comprehensive design and control of oxygen activity in transition-metal-oxide systems for next-generation Li-ion batteries. PMID:27363944

Influence of oxygen on the biosynthesis of polyunsaturated fatty acids in microalgae.

PubMed

Sun, Xiao-Man; Geng, Ling-Jun; Ren, Lu-Jing; Ji, Xiao-Jun; Hao, Ning; Chen, Ke-Quan; Huang, He

2018-02-01

As one of the most important environmental factors, oxygen is particularly important for synthesis of n-3 polyunsaturated fatty acids (n-3 PUFA) in microalgae. In general, a higher oxygen supply is beneficial for cell growth but obstructs PUFA synthesis. The generation of reactive oxygen species (ROS) under aerobic conditions, which leads to the peroxidation of lipids and especially PUFA, is an inevitable aspect of life, but is often ignored in fermentation processes. Irritability, microalgal cells are able to activate a number of anti-oxidative defenses, and the lipid profile of many species is reported to be altered under oxidative stress. In this review, the effects of oxygen on the PUFA synthesis, sources of oxidative damage, and anti-oxidative defense systems of microalgae were summarized and discussed. Moreover, this review summarizes the published reports on microalgal biotechnology involving direct/indirect oxygen regulation and new bioreactor designs that enable the improved production of PUFA. Copyright © 2017 Elsevier Ltd. All rights reserved.

Gas-solid interfacial modification of oxygen activity in layered oxide cathodes for lithium-ion batteries

DOE PAGES

Qiu, Bao; Zhang, Minghao; Wu, Lijun; ...

2016-07-01

Lattice oxygen can play an intriguing role in electrochemical processes, not only maintaining structural stability, but also influencing electron and ion transport properties in high-capacity oxide cathode materials for Li-ion batteries. Here, we report the design of a gas–solid interface reaction to achieve delicate control of oxygen activity through uniformly creating oxygen vacancies without affecting structural integrity of Li-rich layered oxides. Theoretical calculations and experimental characterizations demonstrate that oxygen vacancies provide a favourable ionic diffusion environment in the bulk and significantly suppress gas release from the surface. The target material is achievable in delivering a discharge capacity as high asmore » 301 mAh g –1 with initial Coulombic efficiency of 93.2%. After 100 cycles, a reversible capacity of 300 mAh g –1 still remains without any obvious decay in voltage. Lastly, this study sheds light on the comprehensive design and control of oxygen activity in transition-metal-oxide systems for next-generation Li-ion batteries.« less

Active-oxygen scavenging activity of plant extracts.

PubMed

Masaki, H; Sakaki, S; Atsumi, T; Sakurai, H

1995-01-01

To find antioxidative compounds present in plants, 65 types of plant extract were tested using the neotetrazolium method for evidence of superoxide anion-scavenging effects and 7 plant extracts were selected for further investigation. The activity of active-oxygen scavengers such as superoxide anion radicals, hydroxyl radicals, singlet oxygens and lipid peroxides in the 7 plant extracts (Aeseclus hippocastanum L., Hamamelis virginiana L. Polygonum cuspidatum Sieb., Quercus robur L., Rosemarinous officinalis L., Salvia officinalis L. and Sanguisorba officinalis L.) was examined in detail by both ESR spin-trapping and malondialdehyde generation. Furthermore, the active-oxygen scavenging activity of these plant extracts was evaluated using a murine dermal fibroblast culture system. Both Aeseclus hippocastanum L. and Hamamelis virginia L. were found to have strong active-oxygen scavenging activity of and protective activity against cell damage induced by active oxygen. Both Aeseclus hippocastanum L. and Hamamelis virginiana L. are proposed as potent plant extracts with potential application as anti-aging or anti-wrinkle material for the skin.

Potential and timescales for oxygen depletion in coastal upwelling systems: A box-model analysis

NASA Astrophysics Data System (ADS)

Harrison, C. S.; Hales, B.; Siedlecki, S.; Samelson, R. M.

2016-05-01

A simple box model is used to examine oxygen depletion in an idealized ocean-margin upwelling system. Near-bottom oxygen depletion is controlled by a competition between flushing with oxygenated offshore source waters and respiration of particulate organic matter produced near the surface and retained near the bottom. Upwelling-supplied nutrients are consumed in the surface box, and some surface particles sink to the bottom where they respire, consuming oxygen. Steady states characterize the potential for hypoxic near-bottom oxygen depletion; this potential is greatest for faster sinking rates, and largely independent of production timescales except in that faster production allows faster sinking. Timescales for oxygen depletion depend on upwelling and productivity differently, however, as oxygen depletion can only be reached in meaningfully short times when productivity is rapid. Hypoxia thus requires fast production, to capture upwelled nutrients, and fast sinking, to deliver the respiration potential to model bottom waters. Combining timescales allows generalizations about tendencies toward hypoxia. If timescales of sinking are comparable to or smaller than the sum of those for respiration and flushing, the steady state will generally be hypoxic, and results indicate optimal timescales and conditions exist to generate hypoxia. For example, the timescale for approach to hypoxia lengthens with stronger upwelling, since surface particle and nutrient are shunted off-shelf, in turn reducing subsurface respiration and oxygen depletion. This suggests that if upwelling winds intensify with climate change the increased forcing could offer mitigation of coastal hypoxia, even as the oxygen levels in upwelled source waters decline.

Development of a solid polymer electrolyte electrolysis cell module and ancillary components for a breadboard water electrolysis system

NASA Technical Reports Server (NTRS)

Porter, F. J., Jr.

1972-01-01

Solid polymer electrolyte technology in a water electrolysis system along with ancillary components to generate oxygen and hydrogen for a manned space station application are considered. Standard commercial components are utilized wherever possible. Presented are the results of investigations, surveys, tests, conclusions and recommendations for future development efforts.

Space station solar concentrator materials research

NASA Technical Reports Server (NTRS)

Gulino, Daniel A.

1988-01-01

The Space Station will represent the first time that a solar dynamic power system will be used to generate electrical power in space. In a system such as this, sunlight is collected and focused by a solar concentrator onto the receiver of a heat engine which converts the energy into electricity. The concentrator must be capable of collecting and focusing as much of the incident sunlight as possible, and it must also withstand the atomic oxygen bombardment which occurs in low Earth orbit (LEO). This has led to the development of a system of thin film coatings applied to the concentrator facet surface in a chamber designed especially for this purpose. The system of thin film coatings employed gives both the necessary degree of reflectance and the required protection from the LEO atomic oxygen environment.

Diagram of the Water Recovery and Management for the International Space Station

NASA Technical Reports Server (NTRS)

2000-01-01

This diagram shows the flow of water recovery and management in the International Space Station (ISS). The Environmental Control and Life Support System (ECLSS) Group of the Flight Projects Directorate at the Marshall Space Flight Center is responsible for the regenerative ECLSS hardware, as well as providing technical support for the rest of the system. The regenerative ECLSS, whose main components are the Water Recovery System (WRS), and the Oxygen Generation System (OGS), reclaims and recycles water oxygen. The ECLSS maintains a pressurized habitation environment, provides water recovery and storage, maintains and provides fire detection/ suppression, and provides breathable air and a comfortable atmosphere in which to live and work within the ISS. The ECLSS hardware will be located in the Node 3 module of the ISS.

High throughput photo-oxidations in a packed bed reactor system.

PubMed

Kong, Caleb J; Fisher, Daniel; Desai, Bimbisar K; Yang, Yuan; Ahmad, Saeed; Belecki, Katherine; Gupton, B Frank

2017-12-01

The efficiency gains produced by continuous-flow systems in conducting photochemical transformations have been extensively demonstrated. Recently, these systems have been used in developing safe and efficient methods for photo-oxidations using singlet oxygen generated by photosensitizers. Much of the previous work has focused on the use of homogeneous photocatalysts. The development of a unique, packed-bed photoreactor system using immobilized rose bengal expands these capabilities as this robust photocatalyst allows access to and elaboration from these highly useful building blocks without the need for further purification. With this platform we were able to demonstrate a wide scope of singlet oxygen ene, [4+2] cycloadditions and heteroatom oxidations. Furthermore, we applied this method as a strategic element in the synthesis of the high-volume antimalarial artemisinin. Copyright © 2017. Published by Elsevier Ltd.

Water electrolysis system refurbishment and testing

NASA Technical Reports Server (NTRS)

Greenough, B. M.

1972-01-01

The electrolytic oxygen generator for the back-up water electrolysis system in a 90-day manned test was refurbished, improved and subjected to a 182-day bench test. The performance of the system during the test demonstrated the soundness of the basic electrolysis concept, the high development status of the automatic controls which allowed completely hands-off operation, and the capability for orbital operation. Some design improvements are indicated.

Reduction of acid rock drainage using steel slag in cover systems over sulfide rock waste piles.

PubMed

de Almeida, Rodrigo Pereira; Leite, Adilson do Lago; Borghetti Soares, Anderson

2015-04-01

The extraction of gold, coal, nickel, uranium, copper and other earth-moving activities almost always leads to environmental damage. In metal and coal extraction, exposure of sulfide minerals to the atmosphere leads to generation of acid rock drainage (ARD) and in underground mining to acid mine drainage (AMD) due to contamination of infiltrating groundwater. This study proposes to develop a reactive cover system that inhibits infiltration of oxygen and also releases alkalinity to increase the pH of generated ARD and attenuate metal contaminants at the same time. The reactive cover system is constructed using steel slag, a waste product generated from steel industries. This study shows that this type of cover system has the potential to reduce some of the adverse effects of sulfide mine waste disposal on land. Geochemical and geotechnical characterization tests were carried out. Different proportions of sulfide mine waste and steel slag were studied in leachate extraction tests. The best proportion was 33% of steel slag in dry weight. Other tests were conducted as follows: soil consolidation, saturated permeability and soil water characteristic curve. The cover system was numerically modeled through unsaturated flux analysis using Vadose/w. The solution proposed is an oxygen transport barrier that allows rain water percolation to treat the ARD in the waste rock pile. The results showed that the waste pile slope is an important factor and the cover system must have 5 m thickness to achieve an acceptable effectiveness. © The Author(s) 2015.

Oxygen supersaturated fluid using fine micro/nanobubbles

PubMed Central

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

2014-01-01

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

Oxygen supersaturated fluid using fine micro/nanobubbles.

PubMed

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

2014-01-01

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

LOX/hydrocarbon auxiliary propulsion system study

NASA Technical Reports Server (NTRS)

Orton, G. F.; Mark, T. D.; Weber, D. D.

1982-01-01

Liquid oxygen/hydrocarbon propulsion systems applicable to a second generation orbiter OMS/RCS were compared, and major system/component options were evaluated. A large number of propellant combinations and system concepts were evaluated. The ground rules were defined in terms of candidate propellants, system/component design options, and design requirements. System and engine component math models were incorporated into existing computer codes for system evaluations. The detailed system evaluations and comparisons were performed to identify the recommended propellant combination and system approach.

Preventing hypoxia-induced cell death in beta cells and islets via hydrolytically activated, oxygen-generating biomaterials

PubMed Central

Pedraza, Eileen; Coronel, Maria M.; Fraker, Christopher A.; Ricordi, Camillo; Stabler, Cherie L.

2012-01-01

A major hindrance in engineering tissues containing highly metabolically active cells is the insufficient oxygenation of these implants, which results in dying or dysfunctional cells in portions of the graft. The development of methods to increase oxygen availability within tissue-engineered implants, particularly during the early engraftment period, would serve to allay hypoxia-induced cell death. Herein, we designed and developed a hydrolytically activated oxygen-generating biomaterial in the form of polydimethylsiloxane (PDMS)-encapsulated solid calcium peroxide, PDMS-CaO2. Encapsulation of solid peroxide within hydrophobic PDMS resulted in sustained oxygen generation, whereby a single disk generated oxygen for more than 6 wk at an average rate of 0.026 mM per day. The ability of this oxygen-generating material to support cell survival was evaluated using a β cell line and pancreatic rat islets. The presence of a single PDMS-CaO2 disk eliminated hypoxia-induced cell dysfunction and death for both cell types, resulting in metabolic function and glucose-dependent insulin secretion comparable to that in normoxic controls. A single PDMS-CaO2 disk also sustained enhanced β cell proliferation for more than 3 wk under hypoxic culture conditions. Incorporation of these materials within 3D constructs illustrated the benefits of these materials to prevent the development of detrimental oxygen gradients within large implants. Mathematical simulations permitted accurate prediction of oxygen gradients within 3D constructs and highlighted conditions under which supplementation of oxygen tension would serve to benefit cellular viability. Given the generality of this platform, the translation of these materials to other cell-based implants, as well as ischemic tissues in general, is envisioned. PMID:22371586

Constructing Solid-Gas-Interfacial Fenton Reaction over Alkalinized-C3N4 Photocatalyst To Achieve Apparent Quantum Yield of 49% at 420 nm.

PubMed

Li, Yunxiang; Ouyang, Shuxin; Xu, Hua; Wang, Xin; Bi, Yingpu; Zhang, Yuanfang; Ye, Jinhua

2016-10-03

Efficient generation of active oxygen-related radicals plays an essential role in boosting advanced oxidation process. To promote photocatalytic oxidation for gaseous pollutant over g-C 3 N 4 , a solid-gas interfacial Fenton reaction is coupled into alkalinized g-C 3 N 4 -based photocatalyst to effectively convert photocatalytic generation of H 2 O 2 into oxygen-related radicals. This system includes light energy as power, alkalinized g-C 3 N 4 -based photocatalyst as an in situ and robust H 2 O 2 generator, and surface-decorated Fe 3+ as a trigger of H 2 O 2 conversion, which attains highly efficient and universal activity for photodegradation of volatile organic compounds (VOCs). Taking the photooxidation of isopropanol as model reaction, this system achieves a photoactivity of 2-3 orders of magnitude higher than that of pristine g-C 3 N 4 , which corresponds to a high apparent quantum yield of 49% at around 420 nm. In-situ electron spin resonance (ESR) spectroscopy and sacrificial-reagent incorporated photocatalytic characterizations indicate that the notable photoactivity promotion could be ascribed to the collaboration between photocarriers (electrons and holes) and Fenton process to produce abundant and reactive oxygen-related radicals. The strategy of coupling solid-gas interfacial Fenton process into semiconductor-based photocatalysis provides a facile and promising solution to the remediation of air pollution via solar energy.

Hydrogen peroxide generated by xanthine/xanthine oxidase system represses the proliferation of colorectal cancer cell line Caco-2.

PubMed

Sakuma, Satoru; Abe, Muneyuki; Kohda, Tetsuya; Fujimoto, Yohko

2015-01-01

The twin character of reactive oxygen species is substantiated by a growing body of evidence that reactive oxygen species within cells act as inducers and accelerators of the oncogenic phenotype of cancer cells, while reactive oxygen species can also induce cancer cell death and can therefore function as anti-tumorigenic species. The aim of this study was to assess a possible influence of xanthine/xanthine oxidase on the proliferation of colorectal cancer cell line Caco-2. xanthine/xanthine oxidase (2.5 µM/0.25 mU/ml-25 µM/2.5 mU/ml) dose-dependently inhibited the proliferation of Caco-2 cells. Experiments utilizing reactive oxygen species scavengers (superoxide dismutase, catalase and mannitol) and exogenous hydrogen peroxide revealed a major role of hydrogen peroxide in the xanthine/xanthine oxidase effect. Investigations utilizing annexin V-fluorescein/PI assay using flow cytometry, and the lactate dehydrogenase extracellular release assay indicated that hydrogen peroxide induced necrosis, but not apoptosis, in Caco-2 cells. These results suggest that hydrogen peroxide generated by xanthine/xanthine oxidase has the potential to suppress colorectal cancer cell proliferation.

Hexavalent chromium induces reactive oxygen species and impairs the antioxidant power of human erythrocytes and lymphocytes: Decreased metal reducing and free radical quenching ability of the cells.

PubMed

Husain, Nazim; Mahmood, Riaz

2017-08-01

The toxicity of hexavalent chromium [Cr(VI)] in biological systems is thought to be closely associated with the generation of free radicals and reactive oxygen species. These species are produced when Cr(VI) is reduced to its trivalent form in the cell. This process results in oxidative stress due to an imbalance between the detoxifying ability of the cell and the production of free radicals. We have studied the effect of potassium dichromate (K 2 Cr 2 O 7 ), a [Cr(VI)] compound, on the antioxidant power of human erythrocytes and lymphocytes under in vitro conditions. Incubation of erythrocytes and lymphocytes with different concentrations of K 2 Cr 2 O 7 resulted in a marked dose-dependent decrease in reduced glutathione and an increase in oxidized glutathione and reactive oxygen species levels. The antioxidant power of the cells was decreased, as determined by metal reducing and free radical quenching assays. These results show that [Cr(VI)] upregulates the generation of reactive oxygen species and, as a consequence, the cellular antioxidant defences are compromised. The resulting oxidative stress may contribute to Cr(VI)-induced cellular damage.

Mitochondrial stress controls the radiosensitivity of the oxygen effect: Implications for radiotherapy.

PubMed

Richardson, Richard B; Harper, Mary-Ellen

2016-04-19

It has been more than 60 years since the discovery of the oxygen effect that empirically demonstrates the direct association between cell radiosensitivity and oxygen tension, important parameters in radiotherapy. Yet the mechanisms underlying this principal tenet of radiobiology are poorly understood. Better understanding of the oxygen effect may explain difficulty in eliminating hypoxic tumor cells, a major cause of regrowth after therapy. Our analysis utilizes the Howard-Flanders and Alper formula, which describes the relationship of radiosensitivity with oxygen tension. Here, we assign and qualitatively assess the relative contributions of two important mechanisms. The first mechanism involves the emission of reactive oxygen species from the mitochondrial electron transport chain, which increases with oxygen tension. The second mechanism is related to an energy and repair deficit, which increases with hypoxia. Following a radiation exposure, the uncoupling of the oxidative phosphorylation system (proton leak) in mitochondria lowers the emission of reactive oxygen species which has implications for fractionated radiotherapy, particularly of hypoxic tumors. Our analysis shows that, in oxygenated tumor and normal cells, mitochondria, rather than the nucleus, are the primary loci of radiotherapy effects, especially for low linear energy transfer radiation. Therefore, the oxygen effect can be explained by radiation-induced effects in mitochondria that generate reactive oxygen species, which in turn indirectly target nuclear DNA.

Singlet oxygen generator for a supersonic chemical oxygen iodine laser: parametric study and recovery of chemicals

NASA Astrophysics Data System (ADS)

Spalek, Otomar; Kodymova, Jarmila

1997-04-01

A jet singlet oxygen generator for a supersonic chemical oxygen-iodine laser was studied including singlet delta oxygen, O2(1(Delta) g), and residual chlorine concentration measurements. The investigation was intended mainly for a water vapor measurement in gas effluent of generator in dependence on properties of liquid jets: a chemical composition and temperature of the input liquid (alkaline solution of hydrogen peroxide), a liquid jets diameter and their geometrical arrangement. Effects of these parameters on output power of a small-scale supersonic laser were studied as well. Possible approaches to a chemical fuels management in a chemical oxygen-iodine laser for industrial applications are considered. An 'open loop' cycle with a possible use of sodium hydroxide, and a 'closed loop' cycle with a regeneration of both potassium hydroxide and hydrogen peroxide are discussed.

Kinetic Monte Carlo Simulations of Oxygen Diffusion in Environmental Barrier Coating Materials

NASA Technical Reports Server (NTRS)

Good, Brian S.

2017-01-01

Ceramic Matrix Composite (CMC) materials are of interest for use in next-generation turbine engine components, offering a number of significant advantages, including reduced weight and high operating temperatures. However, in the hot environment in which such components operate, the presence of water vapor can lead to corrosion and recession, limiting the useful life of the components. Such degradation can be reduced through the use of Environmental Barrier Coatings (EBCs) that limit the amount of oxygen and water vapor reaching the component. Candidate EBC materials include Yttrium and Ytterbium silicates. In this work we present results of kinetic Monte Carlo (kMC) simulations of oxygen diffusion, via the vacancy mechanism, in Yttrium and Ytterbium disilicates, along with a brief discussion of interstitial diffusion. An EBC system typically includes a bond coat located between the EBC and the component surface. Bond coat materials are generally chosen for properties other than low oxygen diffusivity, but low oxygen diffusivity is nevertheless a desirable characteristic, as the bond coat could provide some additional component protection, particularly in the case where cracks in the coating system provide a direct path from the environment to the bond coat interface. We have therefore performed similar kMC simulations of oxygen diffusion in this material.

An ISRU Propellant Production System to Fully Fuel a Mars Ascent Vehicle

NASA Technical Reports Server (NTRS)

Kleinhenz, Julie E.; Paz, Aaron

2017-01-01

In-Situ Resource Utilization (ISRU) will enable the long term presence of humans beyond low earth orbit. Since 2009, oxygen production from the Mars atmosphere has been baselined as an enabling technology for Mars human exploration by NASA. However, using water from the Martian regolith in addition to the atmospheric CO2 would enable the production of both liquid Methane and liquid Oxygen, thus fully fueling a Mars return vehicle. A case study was performed to show how ISRU can support NASA's Evolvable Mars Campaign (EMC) using methane and oxygen production from Mars resources. A model was built and used to generate mass and power estimates of an end-to-end ISRU system including excavation and extraction water from Mars regolith, processing the Mars atmosphere, and liquefying the propellants. Even using the lowest yield regolith, a full ISRU system would weigh 1.7 mT while eliminating the need to transport 30 mT of ascent propellants from earth.

Environmental Durability Issues for Solar Power Systems in Low Earth Orbit

NASA Technical Reports Server (NTRS)

Degroh, Kim K.; Banks, Bruce A.; Smith, Daniela C.

1994-01-01

Space solar power systems for use in the low Earth orbit (LEO) environment experience a variety of harsh environmental conditions. Materials used for solar power generation in LEO need to be durable to environmental threats such as atomic oxygen, ultraviolet (UV) radiation, thermal cycling, and micrometeoroid and debris impact. Another threat to LEO solar power performance is due to contamination from other spacecraft components. This paper gives an overview of these LEO environmental issues as they relate to space solar power system materials. Issues addressed include atomic oxygen erosion of organic materials, atomic oxygen undercutting of protective coatings, UV darkening of ceramics, UV embrittlement of Teflon, effects of thermal cycling on organic composites, and contamination due to silicone and organic materials. Specific examples of samples from the Long Duration Exposure Facility (LDEF) and materials returned from the first servicing mission of the Hubble Space Telescope (HST) are presented. Issues concerning ground laboratory facilities which simulate the LEO environment are discussed along with ground-to-space correlation issues.

Reactive oxygen species generation in aqueous solutions containing GdVO4:Eu3+ nanoparticles and their complexes with methylene blue

NASA Astrophysics Data System (ADS)

Hubenko, Kateryna; Yefimova, Svetlana; Tkacheva, Tatyana; Maksimchuk, Pavel; Borovoy, Igor; Klochkov, Vladimir; Kavok, Nataliya; Opolonin, Oleksander; Malyukin, Yuri

2018-04-01

It this letter, we report the study of free radicals and reactive oxygen species (ROS) generation in water solutions containing gadolinium orthovanadate GdVO4:Eu3+ nanoparticles (VNPs) and their complexes with methylene blue (MB) photosensitizer. The catalytic activity was studied under UV-Vis and X-ray irradiation by three methods (conjugated dienes test, OH· radical, and singlet oxygen detection). It has been shown that the VNPs-MB complexes reveal high efficiency of ROS generation under UV-Vis irradiation associated with both high efficiency of OH· radicals generation by VNPs and singlet oxygen generation by MB due to nonradiative excitation energy transfer from VNPs to MB molecules. Contrary to that under X-ray irradiation, the strong OH . radicals scavenging by VNPs has been observed.

Reactive oxygen species generation in aqueous solutions containing GdVO4:Eu3+ nanoparticles and their complexes with methylene blue.

PubMed

Hubenko, Kateryna; Yefimova, Svetlana; Tkacheva, Tatyana; Maksimchuk, Pavel; Borovoy, Igor; Klochkov, Vladimir; Kavok, Nataliya; Opolonin, Oleksander; Malyukin, Yuri

2018-04-13

It this letter, we report the study of free radicals and reactive oxygen species (ROS) generation in water solutions containing gadolinium orthovanadate GdVO 4 :Eu 3+ nanoparticles (VNPs) and their complexes with methylene blue (MB) photosensitizer. The catalytic activity was studied under UV-Vis and X-ray irradiation by three methods (conjugated dienes test, OH· radical, and singlet oxygen detection). It has been shown that the VNPs-MB complexes reveal high efficiency of ROS generation under UV-Vis irradiation associated with both high efficiency of OH· radicals generation by VNPs and singlet oxygen generation by MB due to nonradiative excitation energy transfer from VNPs to MB molecules. Contrary to that under X-ray irradiation, the strong OH . radicals scavenging by VNPs has been observed.

KSC-97pc655

NASA Image and Video Library

1997-04-16

An oxygen generator destined to replace a malfunctioning unit on the Russian Mir Space Station is the object of much curiosity during preflight preparations in the SPACEHAB Payload Processing Facility. A SPACEHAB Double Module on the Space Shuttle Atlantis will carry the oxygen generator to Mir during STS-84, the sixth Shuttle-Mir docking. The nearly 300-pound generator, manufactured by RSC Energia in Russia, will replace one of two Mir units that have been malfunctioning recently. The generator functions by electrolysis, which separates water into its oxygen and hydrogen components. The hydrogen is vented and the oxygen is used for breathing by the Mir crew. The generator is 4.2 feet in length and 1.4 feet in diameter. STS-84, which is planned to include a Mir crew exchange of astronaut C. Michael Foale for Jerry M. Linenger, is targeted for a May 15 liftoff

OGS Maintenance

NASA Image and Video Library

2010-07-21

ISS024-E-009246 (21 July 2010) --- NASA astronaut Tracy Caldwell Dyson, Expedition 24 flight engineer, is pictured during troubleshooting operations of the Oxygen Generator System (OGS) hardware and replacement of an H2 (hydrogen) Dome Orbit Replaceable Unit (ORU) in the Destiny laboratory of the International Space Station.

ISRU System Model Tool: From Excavation to Oxygen Production

NASA Technical Reports Server (NTRS)

Santiago-Maldonado, Edgardo; Linne, Diane L.

2007-01-01

In the late 80's, conceptual designs for an in situ oxygen production plant were documented in a study by Eagle Engineering [1]. In the "Summary of Findings" of this study, it is clearly pointed out that: "reported process mass and power estimates lack a consistent basis to allow comparison." The study goes on to say: "A study to produce a set of process mass, power, and volume requirements on a consistent basis is recommended." Today, approximately twenty years later, as humans plan to return to the moon and venture beyond, the need for flexible up-to-date models of the oxygen extraction production process has become even more clear. Multiple processes for the production of oxygen from lunar regolith are being investigated by NASA, academia, and industry. Three processes that have shown technical merit are molten regolith electrolysis, hydrogen reduction, and carbothermal reduction. These processes have been selected by NASA as the basis for the development of the ISRU System Model Tool (ISMT). In working to develop up-to-date system models for these processes NASA hopes to accomplish the following: (1) help in the evaluation process to select the most cost-effective and efficient process for further prototype development, (2) identify key parameters, (3) optimize the excavation and oxygen production processes, and (4) provide estimates on energy and power requirements, mass and volume of the system, oxygen production rate, mass of regolith required, mass of consumables, and other important parameters. Also, as confidence and high fidelity is achieved with each component's model, new techniques and processes can be introduced and analyzed at a fraction of the cost of traditional hardware development and test approaches. A first generation ISRU System Model Tool has been used to provide inputs to the Lunar Architecture Team studies.

Physics and chemistry of the influence of excited molecules on combustion enhancement

PubMed Central

Starik, A. M.; Loukhovitski, B. I.; Sharipov, A. S.; Titova, N. S

2015-01-01

The paper addresses detailed analysis of kinetic processes in the H2−O2, CO−O2 and CH4−O2-reactive systems upon the presence of singlet oxygen molecules O2(a1Δg) and and the influence of the activation of oxygen molecules in electric discharge on the acceleration of ignition in the H2−O2 and CH4−O2 mixtures. The possibility of the intensification of CO oxidation due to excitation of O2 and N2 molecule vibrations and generation of singlet oxygen molecules is also considered. It is shown that the effect of accelerating the ignition strongly depends on the reduced electric field and, as a consequence, on the composition of discharge plasma as well as on the features of chain mechanism development in oxy-fuel systems. It is revealed that the most effective approach for the intensification of CO oxidation both in the moist air and in the products of hydrocarbon combustion in air is the generation of O2(a1Δg) molecules by electric discharge. Computations showed that the presence of 1% O2(a1Δg) in the total oxygen allowed one to convert CO to CO2 even at the temperature T=850–900 K in the time of 10−2 s. The excitation of O2 and N2 molecule vibrations is less effective for such a conversion. PMID:26170425

Feasibility Analysis of Liquefying Oxygen Generated from Water Electrolysis Units on Lunar Surface

NASA Technical Reports Server (NTRS)

Jeng, Frank F.

2009-01-01

Concepts for liquefying oxygen (O2) generated from water electrolysis subsystems on the Lunar surface were explored. Concepts for O2 liquefaction units capable of generating 1.38 lb/hr (0.63 kg/hr) liquid oxygen (LOX) were developed. Heat and mass balance calculations for the liquefaction concepts were conducted. Stream properties, duties of radiators, heat exchangers and compressors for the selected concepts were calculated and compared.

Polymer membrane based electrolytic cell and process for the direct generation of hydrogen peroxide in liquid streams

NASA Technical Reports Server (NTRS)

White, James H. (Inventor); Schwartz, Michael (Inventor); Sammells, Anthony F. (Inventor)

1997-01-01

An electrolytic cell for generating hydrogen peroxide is provided including a cathode containing a catalyst for the reduction of oxygen, and an anode containing a catalyst for the oxidation of water. A polymer membrane, semipermeable to either protons or hydroxide ions is also included and has a first face interfacing to the cathode and a second face interfacing to the anode so that when a stream of water containing dissolved oxygen or oxygen bubbles is passed over the cathode and a stream of water is passed over the anode, and an electric current is passed between the anode and the cathode, hydrogen peroxide is generated at the cathode and oxygen is generated at the anode.

Tracking performance with two breathing oxygen concentrations after high altitude rapid decompression

NASA Technical Reports Server (NTRS)

Nesthus, Thomas E.; Schiflett, Samuel G.; Oakley, Carolyn J.

1992-01-01

Current military aircraft Liquid Oxygen (LOX) systems supply 99.5 pct. gaseous Aviator's Breathing Oxygen (ABO) to aircrew. Newer Molecular Sieve Oxygen Generation Systems (MSOGS) supply breathing gas concentration of 93 to 95 pct. O2. The margin is compared of hypoxia protection afforded by ABO and MSOGS breathing gas after a 5 psi differential rapid decompression (RD) in a hypobaric research chamber. The barometric pressures equivalent to the altitudes of 46000, 52000, 56000, and 60000 ft were achieved from respective base altitudes in 1 to 1.5 s decompressions. During each exposure, subjects remained at the simulated peak altitude breathing either 100 or 94 pct. O2 with positive pressure for 60 s, followed by a rapid descent to 40000 ft. Subjects used the Tactical Life Support System (TLSS) for high altitude protection. Subcritical tracking task performance on the Performance Evaluation Device (PED) provided psychomotor test measures. Overall tracking task performance results showed no differences between the MSOGS breathing O2 concentration of 94 pct. and ABO. Significance RMS error differences were found between the ground level and base altitude trials compared to peak altitude trials. The high positive breathing pressures occurring at the peak altitudes explained the differences.

Pegylated and nanoparticle-conjugated sulfonium salt photo triggers necrotic cell death.

PubMed

Fadhel, Alaa A; Yue, Xiling; Ghazvini Zadeh, Ebrahim H; Bondar, Mykhailo V; Belfield, Kevin D

Photodynamic therapy (PDT) processes involving the production of singlet oxygen face the issue of oxygen concentration dependency. Despite high oxygen delivery, a variety of properties related to metabolism and vascular morphology in cancer cells result in hypoxic environments, resulting in limited effectiveness of such therapies. An alternative oxygen-independent agent whose cell cytotoxicity can be remotely controlled by light may allow access to treatment of hypoxic tumors. Toward that end, we developed and tested both polyethylene glycol (PEG)-functionalized and hydrophilic silica nanoparticle (SiNP)-enriched photoacid generator (PAG) as a nontraditional PDT agent to effectively induce necrotic cell death in HCT-116 cells. Already known for applications in lithography and cationic polymerization, our developed oxygen-independent PDT, whether free or highly monodispersed on SiNPs, generates acid when a one-photon (1P) or two-photon (2P) excitation source is used, thus potentially permitting deep tissue treatment. Our study shows that when conjugated to SiNPs with protruding amine functionalities (SiNP-PAG9), such atypical PDT agents can be effectively delivered into HCT-116 cells and compartmentalize exclusively in lysosomes and endosomes. Loss of cell adhesion and cell swelling are detected when an excitation source is applied, suggesting that SiNP-PAG9, when excited via near-infrared 2P absorption (a subject of future investigation), can be used as a delivery system to selectively induce cell death in oxygen-deprived optically thick tissue.

A multisyringe flow injection Winkler-based spectrophotometric analyzer for in-line monitoring of dissolved oxygen in seawater.

PubMed

Horstkotte, Burkhard; Alonso, Juan Carlos; Miró, Manuel; Cerdà, Víctor

2010-01-15

An integrated analyzer based on the multisyringe flow injection analysis approach is proposed for the automated determination of dissolved oxygen in seawater. The entire Winkler method including precipitation of manganese(II) hydroxide, fixation of dissolved oxygen, dissolution of the oxidized manganese hydroxide precipitate, and generation of iodine and tri-iodide ion are in-line effected within the flow network. Spectrophotometric quantification of iodine and tri-iodide at the isosbestic wavelength of 466nm renders enhanced method reliability. The calibration function is linear up to 19mgL(-1) dissolved oxygen and an injection frequency of 17 per hour is achieved. The multisyringe system features a highly satisfying signal stability with repeatabilities of 2.2% RSD that make it suitable for continuous determination of dissolved oxygen in seawater. Compared to the manual starch-end-point titrimetric Winkler method and early reported automated systems, concentrations and consumption of reagents and sample are reduced up to hundredfold. The versatility of the multisyringe assembly was exploited in the implementation of an ancillary automatic batch-wise Winkler titrator using a single syringe of the module for accurate titration of the released iodine/tri-iodide with thiosulfate.

Combining plasma gasification and solid oxide cell technologies in advanced power plants for waste to energy and electric energy storage applications.

PubMed

Perna, Alessandra; Minutillo, Mariagiovanna; Lubrano Lavadera, Antonio; Jannelli, Elio

2018-03-01

The waste to energy (WtE) facilities and the renewable energy storage systems have a strategic role in the promotion of the "eco-innovation", an emerging priority in the European Union. This paper aims to propose advanced plant configurations in which waste to energy plants and electric energy storage systems from intermittent renewable sources are combined for obtaining more efficient and clean energy solutions in accordance with the "eco-innovation" approach. The advanced plant configurations consist of an electric energy storage (EES) section based on a solid oxide electrolyzer (SOEC), a waste gasification section based on the plasma technology and a power generation section based on a solid oxide fuel cell (SOFC). The plant configurations differ for the utilization of electrolytic hydrogen and oxygen in the plasma gasification section and in the power generation section. In the first plant configuration IAPGFC (Integrated Air Plasma Gasification Fuel Cell), the renewable oxygen enriches the air stream, that is used as plasma gas in the gasification section, and the renewable hydrogen is used to enrich the anodic stream of the SOFC in the power generation section. In the second plant configuration IHPGFC (Integrated Hydrogen Plasma Gasification Fuel Cell) the renewable hydrogen is used as plasma gas in the plasma gasification section, and the renewable oxygen is used to enrich the cathodic stream of the SOFC in the power generation section. The analysis has been carried out by using numerical models for predicting and comparing the systems performances in terms of electric efficiency and capability in realizing the waste to energy and the electric energy storage of renewable sources. Results have highlighted that the electric efficiency is very high for all configurations (35-45%) and, thanks to the combination with the waste to energy technology, the storage efficiencies are very attractive (in the range 72-92%). Copyright © 2017 Elsevier Ltd. All rights reserved.

Flow-injection assay of catalase activity.

PubMed

Ukeda, Hiroyuki; Adachi, Yukiko; Sawamura, Masayoshi

2004-03-01

A novel flow-injection assay (FIA) system with a double line for catalase activity was constructed in which an oxidase is immobilized and the substrate is continuously pumped to reduce the dissolved oxygen and to generate a given level of hydrogen peroxide. The catalase in a sample decomposed the hydrogen peroxide, and thus the increase in dissolved oxygen dependent on the activity was amperometrically monitored using a Clark-type oxygen electrode. Among the examined several oxidases, uricase was most suitable for the continuous formation of hydrogen peroxide from a consideration of the stability and the conversion efficiency. Under the optimum conditions, a linear calibration curve was obtained in the range from 21 to 210 units/mg and the reproducibility (CV) was better than 2% by 35 successive determinations of 210 units/ml catalase preparation. The sampling frequency was about 15 samples/h. The present FIA system was applicable to monitor the inactivation of catalase by glycation.

Regulation of signal transduction by reactive oxygen species in the cardiovascular system

PubMed Central

Brown, David I.; Griendling, Kathy K.

2015-01-01

Oxidative stress has long been implicated in cardiovascular disease, but more recently, the role of reactive oxygen species in normal physiological signaling has been elucidated. Signaling pathways modulated by reactive oxygen species (ROS) are complex and compartmentalized, and we are only beginning to identify the molecular modifications of specific targets. Here we review the current literature regarding ROS signaling in the cardiovascular system, focusing on the role of ROS in normal physiology and how dysregulation of signaling circuits contributes to cardiovascular diseases including atherosclerosis, ischemia-reperfusion injury, cardiomyopathy and heart failure. In particular, we consider how ROS modulate signaling pathways related to phenotypic modulation, migration and adhesion, contractility, proliferation and hypertrophy, angiogenesis, endoplasmic reticulum stress, apoptosis and senescence. Understanding the specific targets of ROS may guide the development of the next generation of ROS-modifying therapies to reduce morbidity and mortality associated with oxidative stress. PMID:25634975

Linear aerospike engine study. [for reusable launch vehicles

NASA Technical Reports Server (NTRS)

Diem, H. G.; Kirby, F. M.

1977-01-01

Parametric data on split-combustor linear engine propulsion systems are presented for use in mixed-mode single-stage-to-orbit (SSTO) vehicle studies. Preliminary design data for two selected engine systems are included. The split combustor was investigated for mixed-mode operations with oxygen/hydrogen propellants used in the inner combustor in Mode 2, and in conjunction with either oxygen/RP-1, oxygen/RJ-5, O2/CH4, or O2/H2 propellants in the outer combustor for Mode 1. Both gas generator and staged combustion power cycles were analyzed for providing power to the turbopumps of the inner and outer combustors. Numerous cooling circuits and cooling fluids (propellants) were analyzed and hydrogen was selected as the preferred coolant for both combustors and the linear aerospike nozzle. The maximum operating chamber pressure was determined to be limited by the availability of hydrogen coolant pressure drop in the coolant circuit.

Catalysts for electrochemical generation of oxygen

NASA Technical Reports Server (NTRS)

Hagans, P.; Yeager, E.

1978-01-01

Single crystal surfaces of platinum and gold and transition metal oxides of the spinel type were studied to find more effective catalysts for the electrolytic evolution of oxygen and to understand the mechanism and kinetics for the electrocatalysis in relation to the surface electronic and lattice properties of the catalyst. The single crystal studies involve the use of low energy electron diffraction (LEED) and Auger electron spectroscopy as complementary tools to the electrochemical measurements. Modifications to the transfer system and to the thin-layer electrochemical cell used to facilitate the transfer between the ultrahigh vacuum environment of the electron surface physics equipment and the electrochemical environment with a minimal possibility of changes in the surface structure, are described. The electrosorption underpotential deposition of Pb onto the Au(111), (100) and (110) single crystal surfaces with the thin-layer cell-LEED-Auger system is discussed as well as the synthesis of spinels for oxygen evolution studies.

International Space Station (ISS)

NASA Image and Video Library

2001-03-01

The Environmental Control and Life Support System (ECLSS) Group of the Flight Projects Directorate at the Marshall Space Flight Center in Huntsville, Alabama, is responsible for designing and building the life support systems that will provide the crew of the International Space Station (ISS) a comfortable environment in which to live and work. This photograph shows the mockup of the the ECLSS to be installed in the Node 3 module of the ISS. From left to right, shower rack, waste management rack, Water Recovery System (WRS) Rack #2, WRS Rack #1, and Oxygen Generation System (OGS) rack are shown. The WRS provides clean water through the reclamation of wastewaters and is comprised of a Urine Processor Assembly (UPA) and a Water Processor Assembly (WPA). The UPA accepts and processes pretreated crewmember urine to allow it to be processed along with other wastewaters in the WPA. The WPA removes free gas, organic, and nonorganic constituents before the water goes through a series of multifiltration beds for further purification. The OGS produces oxygen for breathing air for the crew and laboratory animals, as well as for replacing oxygen loss. The OGS is comprised of a cell stack, which electrolyzes (breaks apart the hydrogen and oxygen molecules) some of the clean water provided by the WRS, and the separators that remove the gases from the water after electrolysis.

Microfabricated Collector-Generator Electrode Sensor for Measuring Absolute pH and Oxygen Concentrations.

PubMed

Dengler, Adam K; Wightman, R Mark; McCarty, Gregory S

2015-10-20

Fast-scan cyclic voltammetry (FSCV) has attracted attention for studying in vivo neurotransmission due to its subsecond temporal resolution, selectivity, and sensitivity. Traditional FSCV measurements use background subtraction to isolate changes in the local electrochemical environment, providing detailed information on fluctuations in the concentration of electroactive species. This background subtraction removes information about constant or slowly changing concentrations. However, determination of background concentrations is still important for understanding functioning brain tissue. For example, neural activity is known to consume oxygen and produce carbon dioxide which affects local levels of oxygen and pH. Here, we present a microfabricated microelectrode array which uses FSCV to detect the absolute levels of oxygen and pH in vitro. The sensor is a collector-generator electrode array with carbon microelectrodes spaced 5 μm apart. In this work, a periodic potential step is applied at the generator producing transient local changes in the electrochemical environment. The collector electrode continuously performs FSCV enabling these induced changes in concentration to be recorded with the sensitivity and selectivity of FSCV. A negative potential step applied at the generator produces a transient local pH shift at the collector. The generator-induced pH signal is detected using FSCV at the collector and correlated to absolute solution pH by postcalibration of the anodic peak position. In addition, in oxygenated solutions a negative potential step at the generator produces hydrogen peroxide by reducing oxygen. Hydrogen peroxide is detected with FSCV at the collector electrode, and the magnitude of the oxidative peak is proportional to absolute oxygen concentrations. Oxygen interference on the pH signal is minimal and can be accounted for with a postcalibration.

Oxygen-Partial-Pressure Sensor for Aircraft Oxygen Mask

NASA Technical Reports Server (NTRS)

Kelly, Mark; Pettit, Donald

2003-01-01

A device that generates an alarm when the partial pressure of oxygen decreases to less than a preset level has been developed to help prevent hypoxia in a pilot or other crewmember of a military or other high-performance aircraft. Loss of oxygen partial pressure can be caused by poor fit of the mask or failure of a hose or other component of an oxygen distribution system. The deleterious physical and mental effects of hypoxia cause the loss of a military aircraft and crew every few years. The device is installed in the crewmember s oxygen mask and is powered via communication wiring already present in all such oxygen masks. The device (see figure) includes an electrochemical sensor, the output potential of which is proportional to the partial pressure of oxygen. The output of the sensor is amplified and fed to the input of a comparator circuit. A reference potential that corresponds to the amplified sensor output at the alarm oxygen-partial-pressure level is fed to the second input of the comparator. When the sensed partial pressure of oxygen falls below the minimum acceptable level, the output of the comparator goes from the low state (a few millivolts) to the high state (near the supply potential, which is typically 6.8 V for microphone power). The switching of the comparator output to the high state triggers a tactile alarm in the form of a vibration in the mask, generated by a small 1.3-Vdc pager motor spinning an eccentric mass at a rate between 8,000 and 10,000 rpm. The sensation of the mask vibrating against the crewmember s nose is very effective at alerting the crewmember, who may already be groggy from hypoxia and is immersed in an environment that is saturated with visual cues and sounds. Indeed, the sensation is one of rudeness, but such rudeness could be what is needed to stimulate the crewmember to take corrective action in a life-threatening situation.

Test results of six-month test of two water electrolysis systems

NASA Technical Reports Server (NTRS)

Mills, E. S.; Wells, G. W.

1972-01-01

The two water electrolysis systems used in the NASA space station simulation 90-day manned test of a regenerative life support system were refurbished as required and subjected to 26-weeks of testing. The two electrolysis units are both promising systems for oxygen and hydrogen generation and both needed extensive long-term testing to evaluate the performance of the respective cell design and provide guidance for further development. Testing was conducted to evaluate performance in terms of current, pressure, variable oxygen demands, and orbital simulation. An automatic monitoring system was used to record, monitor and printout performance data at one minute, ten minute or one-hour intervals. Performance data is presented for each day of system operation for each module used during the day. Failures are analyzed, remedial action taken to eliminate problems is discussed and recommendations for redesign for future space applications are stated.

Estimating Oxygen Needs for Childhood Pneumonia in Developing Country Health Systems: A New Model for Expecting the Unexpected

PubMed Central

Bradley, Beverly D.; Howie, Stephen R. C.; Chan, Timothy C. Y.; Cheng, Yu-Ling

2014-01-01

Background Planning for the reliable and cost-effective supply of a health service commodity such as medical oxygen requires an understanding of the dynamic need or ‘demand’ for the commodity over time. In developing country health systems, however, collecting longitudinal clinical data for forecasting purposes is very difficult. Furthermore, approaches to estimating demand for supplies based on annual averages can underestimate demand some of the time by missing temporal variability. Methods A discrete event simulation model was developed to estimate variable demand for a health service commodity using the important example of medical oxygen for childhood pneumonia. The model is based on five key factors affecting oxygen demand: annual pneumonia admission rate, hypoxaemia prevalence, degree of seasonality, treatment duration, and oxygen flow rate. These parameters were varied over a wide range of values to generate simulation results for different settings. Total oxygen volume, peak patient load, and hours spent above average-based demand estimates were computed for both low and high seasons. Findings Oxygen demand estimates based on annual average values of demand factors can often severely underestimate actual demand. For scenarios with high hypoxaemia prevalence and degree of seasonality, demand can exceed average levels up to 68% of the time. Even for typical scenarios, demand may exceed three times the average level for several hours per day. Peak patient load is sensitive to hypoxaemia prevalence, whereas time spent at such peak loads is strongly influenced by degree of seasonality. Conclusion A theoretical study is presented whereby a simulation approach to estimating oxygen demand is used to better capture temporal variability compared to standard average-based approaches. This approach provides better grounds for health service planning, including decision-making around technologies for oxygen delivery. Beyond oxygen, this approach is widely applicable to other areas of resource and technology planning in developing country health systems. PMID:24587089

LuAG:Pr3+-porphyrin based nanohybrid system for singlet oxygen production: Toward the next generation of PDTX drugs.

PubMed

Popovich, Kseniya; Tomanová, Kateřina; Čuba, Václav; Procházková, Lenka; Pelikánová, Iveta Terezie; Jakubec, Ivo; Mihóková, Eva; Nikl, Martin

2018-02-01

A highly prospective drug for the X-ray induced photodynamic therapy (PDTX), LuAG:Pr 3+ @SiO 2 -PpIX nanocomposite, was successfully prepared by a three step process: photo-induced precipitation of the Lu 3 Al 5 O 12 :Pr 3+ (LuAG:Pr 3+ ) core, sol-gel technique for amorphous silica coating, and a biofunctionalization by attaching the protoporphyrin IX (PpIX) molecules. The synthesis procedure provides three-layer nanocomposite with uniform shells covering an intensely luminescent core. Room temperature radioluminescence (RT RL) spectra as well as photoluminescence (RT PL) steady-state and time resolved spectra of the material confirm the non-radiative energy transfer from the core Pr 3+ ions to the PpIX outer layer. First, excitation of Pr 3+ ions results in the red luminescence of PpIX. Second, the decay measurements exhibit clear evidence of mentioned non-radiative energy transfer (ET). The singlet oxygen generation in the system was demonstrated by the 3'-(p-aminophenyl) fluorescein (APF) chemical probe sensitive to the singlet oxygen presence. The RT PL spectra of an X-ray irradiated material with the APF probe manifest the formation of singlet oxygen due to which enhanced luminescence around 530 nm is observed. Quenching studies, using NaN 3 as an 1 O 2 inhibitor, also confirm the presence of 1 O 2 in the system and rule out the parasitic reaction with OH radicals. To summarize, presented features of LuAG:Pr 3+ @SiO 2 -PpIX nanocomposite indicate its considerable potential for PDTX application. Copyright © 2018 Elsevier B.V. All rights reserved.

Are acetylcholine-induced acetyl groups driving fuel cells in the systems of transducin, t and G proteins?

PubMed

Nyberg-Swenson, B E

2002-05-01

Life is completely dependent on a support of energy which is generated by the direct absorption of light or by the reduction of oxygen. Metabolized food yields ac(et)yl groups which are utilized in the reduction of oxygen with the assistance of many other compounds. Acetylcholine appears to be an important substance for the transportation of acetyl groups. Acetylcholine activates systems regulated by transducin, t and G proteins, probably Se enzymes, reacting by similar mechanisms in triggered reactions ending in nerve or muscle signals. These activations are performed by GTP (or ATP), probably resulting from the reactions of acetylcholine-induced acetyl groups. The inactivation-activation states of these systems are regulated by changes of GTP to cGMP to GMP which form a loop.Diminished support of energy to systems, because of impaired charge transfer to oxygen, may be responsible for many diseases. For example, there is a low level of acetylcholine in the brains of patients with Alzheimer's disease. Copyright 2002 Elsevier Science Ltd. All Rights reserved.

Photo-oxidation of ergosterol: indirect detection of antioxidants photosensitizers or quenchers of singlet oxygen.

PubMed

Lagunes, Irene; Trigos, Ángel

2015-04-01

Consumption of antioxidant supplements is associated to prevention of several diseases. However, recent studies suggest that antioxidants, besides scavenge free radicals could lead development of tumors. Due to conflicting reports on the antioxidant benefits, the capacity to photosensitize the generation of singlet oxygen of seven natural antioxidants was evaluated through photo-oxidation of ergosterol which proved to be an efficient method of indirect detection of singlet oxygen. Our results showed that curcumin, resveratrol and quercetin have pro-oxidant activity due they act as photosensitizers in generation of singlet oxygen. In addition, we observed that genistein, naringenin, β-carotene and gallic acid besides their antioxidant activity against ROS radicals, are capable of quenching ROS non-radicals as singlet oxygen. Finally, our results allow us to propose a new approach in classification of natural antioxidants scavengers of free radicals, based on their activity as quenchers of singlet oxygen or as photosensitizers in singlet oxygen generation. Copyright © 2015. Published by Elsevier B.V.

A Bifunctional Photosensitizer for Enhanced Fractional Photodynamic Therapy: Singlet Oxygen Generation in the Presence and Absence of Light.

PubMed

Turan, Ilke Simsek; Yildiz, Deniz; Turksoy, Abdurrahman; Gunaydin, Gurcan; Akkaya, Engin U

2016-02-18

The photosensitized generation of singlet oxygen within tumor tissues during photodynamic therapy (PDT) is self-limiting, as the already low oxygen concentrations within tumors is further diminished during the process. In certain applications, to minimize photoinduced hypoxia the light is introduced intermittently (fractional PDT) to allow time for the replenishment of cellular oxygen. This condition extends the time required for effective therapy. Herein, we demonstrated that a photosensitizer with an additional 2-pyridone module for trapping singlet oxygen would be useful in fractional PDT. Thus, in the light cycle, the endoperoxide of 2-pyridone is generated along with singlet oxygen. In the dark cycle, the endoperoxide undergoes thermal cycloreversion to produce singlet oxygen, regenerating the 2-pyridone module. As a result, the photodynamic process can continue in the dark as well as in the light cycles. Cell-culture studies validated this working principle in vitro. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

46 CFR 154.906 - Inert gas generators.

Code of Federal Regulations, 2012 CFR

2012-10-01

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

46 CFR 154.906 - Inert gas generators.

Code of Federal Regulations, 2014 CFR

2014-10-01

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

46 CFR 154.906 - Inert gas generators.

Code of Federal Regulations, 2013 CFR

2013-10-01

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

46 CFR 154.906 - Inert gas generators.

Code of Federal Regulations, 2011 CFR

2011-10-01

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

46 CFR 154.906 - Inert gas generators.

Code of Federal Regulations, 2010 CFR

2010-10-01

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

[Generation of Superoxide Radicals by Complex III in Heart Mitochondria and Antioxidant Effect of Dinitrosyl Iron Complexes at Different Partial Pressure of Oxygen].

PubMed

Dudylina, A L; Ivanova, M V; Shumaev, K B; Ruuge, E K

2016-01-01

The EPR spin-trapping technique and EPR-oximetry were used to study generation of superoxide radicals in heart mitochondria isolated from Wistar rats under conditions of variable oxygen concentration. Lithium phthalocyanine and TEMPONE-15N-D16 were chosen to determine oxygen content in a gas-permeable capillary tube containing mitochondria. TIRON was used as a spin trap. We investigated the influence of different oxygen concentrations in incubation mixture and demonstrated that heart mitochondria can generate superoxide in complex III at different partial pressure of oxygen as well as under the conditions of deep hypoxia (< 5% O2). Dinitrosyl iron complexes with glutathione (the pharmaceutical drug "Oxacom") exerted an antioxidant effect, regardless of the value of the partial pressure of oxygen, but the magnitude and kinetic characteristics of the effect depended on the concentration of the drug.

Biochar supported nanoscale zerovalent iron composite used as persulfate activator for removing trichloroethylene.

PubMed

Yan, Jingchun; Han, Lu; Gao, Weiguo; Xue, Song; Chen, Mengfang

2015-01-01

Biochar (BC) supported nanoscale zerovalent iron (nZVI) composite was synthesized and used as an activator for persulfate to enhance the trichloroethylene (TCE) removal in aqueous solutions. The degradation efficiency of TCE (0.15mmolL(-1)) was 99.4% in the presence of nZVI/BC (4.5mmolL(-1), nZVI to BC mass ratio was 1:5) and persulfate (4.5mmolL(-1)) within 5min, which was significantly higher than that (56.6%) in nZVI-persulfate system under the same conditions. Owing to large specific surface area and oxygen-containing functional groups of BC, nZVI/BC enhanced the SO4(-) generation and accelerated TCE degradation. On the basis of the characterization and analysis data, possible activation mechanisms of the Fe(2+)/Fe(3+) (Fe(II)/Fe(III)) redox action and the electron-transfer mediator of the BC oxygen functional groups promoting the generation of SO4(-) in nZVI/BC-persulfate system were clarified. Copyright © 2014 Elsevier Ltd. All rights reserved.

The structure optimization of gas-phase surface discharge and its application for dye degradation

NASA Astrophysics Data System (ADS)

Ying, CAO; Jie, LI; Nan, JIANG; Yan, WU; Kefeng, SHANG; Na, LU

2018-05-01

A gas-phase surface discharge (GSD) was employed to optimize the discharge reactor structure and investigate the dye degradation. A dye mixture of methylene blue, acid orange and methyl orange was used as a model pollutant. The results indicated that the reactor structure of the GSD system with the ratio of tube inner surface area and volume of 2.48, screw pitch between a high-voltage electrode of 9.7 mm, high-voltage electrode wire diameter of 0.8 mm, dielectric tube thickness of 2.0 mm and tube inner diameter of 16.13 mm presented a better ozone (O3) generation efficiency. Furthermore, a larger screw pitch and smaller wire diameter enhanced the O3 generation. After the dye mixture degradation by the optimized GSD system, 73.21% and 50.74% of the chemical oxygen demand (COD) and total organic carbon removal rate were achieved within 20 min, respectively, and the biochemical oxygen demand (BOD) and biodegradability (BOD/COD) improved.

Solid electrolyte oxygen regeneration system

NASA Technical Reports Server (NTRS)

Shumar, J. W.; See, G. G.; Schubert, F. H.; Powell, J. D.

1976-01-01

A program to design, develop, fabricate and assemble a one-man, self-contained, solid electrolyte oxygen regeneration system (SX-1) incorporating solid electrolyte electrolyzer drums was completed. The SX-1 is a preprototype engineering model designed to produce 0.952 kg (2.1 lb)/day of breathable oxygen (O2) from the electrolysis of metabolic carbon dioxide (CO2) and water vapor. The CO2 supply rate was established based on the metabolic CO2 generation rate for one man of 0.998 kg (2.2 lb)/day. The water supply rate (0.254 kg (0.56 lb)/day) was designed to be sufficient to make up the difference between the 0.952 kg (2.1 lb)/day O2 generation specification and the O2 available through CO2 electrolysis, 0.726 kg (1.6 lb)/day. The SX-1 was successfully designed, fabricated and assembled. Design verification tests (DVT) or the CO Disproportionators, H2 separators, control instrumentation, monitor instrumentation, water feed mechanism were successfully completed. The erratic occurrence of electrolyzer drum leakage prevented the completion of the CO2 electrolyzer module and water electrolyzer module DVT's and also prevented the performance of SX-1 integrated testing. Further development work is required to improve the solid electrolyte cell high temperature seals.

KSC-97pc672

NASA Image and Video Library

1997-04-19

McDonnell Douglas-SPACEHAB technicians oversee the move of a Russian-made oxygen generator to a SPACEHAB Double Module, at rear, in the SPACEHAB Payload Processing Facility. In foreground, from left, are Marc Tuttle, Dan Porter and Mike Vawter. The oxygen generator, manufactured in Russia by RSC Energia, will be carried aboard the Space Shuttle Atlantis on Mission STS-84 for the Shuttle’s scheduled docking with the Russian Space Station Mir next month. The nearly 300-pound generator will replace one of two Mir units that have been malfunctioning recently. The generator functions by electrolysis, which separates water into its oxygen and hydrogen components. The hydrogen is vented and the oxygen is used for breathing by the Mir crew. The generator is 4.2 feet in length and 1.4 feet in diameter. STS-84, which is planned to include a Mir crew exchange of astronaut C. Michael Foale for Jerry M. Linenger, is targeted for a May 15 liftoff

A proposed national wind power R and D program. [offshore wind power system for electric energy supplies

NASA Technical Reports Server (NTRS)

Heronemus, W.

1973-01-01

An offshore wind power system is described that consists of wind driven electrical dc generators mounted on floating towers in offshore waters. The output from the generators supplies underwater electrolyzer stations in which water is converted into hydrogen and oxygen. The hydrogen is piped to shore for conversion to electricity in fuel cell stations. It is estimated that this system can produce 159 x 10 to the ninth power kilowatt-hours per year. It is concluded that solar energy - and that includes wind energy - is the only way out of the US energy dilemma in the not too distant future.

Formation of carbon monoxide during mouse hepatic microsomal oxidative metabolism of cannabidiol; identification and determination.

PubMed

Usami, N; Tateoka, Y; Watanabe, K; Yamamoto, I; Yoshimura, H

1995-04-01

Carbon monoxide (CO) was generated in the process of hepatic microsomal oxidative metabolism of cannabidiol (CBD). After the generated CO was reduced to methane (CH4) with a methanizer, CH4 formed was determined by gas chromatography (GC) with a flame ionization detector. After oxidation with hopcalite, CO was also identified as CO2 by gas chromatography/mass spectrometry (GC/MS). The reaction was NADPH-dependent and required molecular oxygen. It was inhibited by addition of some inhibitors of cytochrome P450-dependent monooxygenase. When CBD (191 microM) was incubated with hepatic microsomes of mice in the presence of an NADPH-generating system and oxygen, concentration of CO determined by GC was 4.7 +/- 0.5 ppm/nmol P450 in the incubation atmosphere. Pretreatment with phenobarbital (100 mg/kg, i.p. for 3d) but not 3-methylcholanthrene (80 mg/kg, i.p.) increased the CO formation 78%, while pretreatment with cobaltous chloride (40 mg/kg, i.p. for 3 d) decreased the formation 56%. When CBD was incubated under oxygen-18 gas, molecular oxygen was not incorporated into the CO molecule. 8,9-Dihydro- and 1,2,8,9-tetrahydro-CBDs also produced CO to some extent, whereas CBD monomethyl- and dimethylethers reduced the ability to produce CO. In addition, cannabidivarin and olivetol produced CO, although none of delta 9-tetrahydrocannabinol, cannabinol and d-limonene did. Thus, the resorcinol moiety of CBD is important for CO formation.

Environmental Control and Life Support System Mockup

NASA Technical Reports Server (NTRS)

2001-01-01

The Environmental Control and Life Support System (ECLSS) Group of the Flight Projects Directorate at the Marshall Space Flight Center in Huntsville, Alabama, is responsible for designing and building the life support systems that will provide the crew of the International Space Station (ISS) a comfortable environment in which to live and work. This photograph shows the mockup of the the ECLSS to be installed in the Node 3 module of the ISS. From left to right, shower rack, waste management rack, Water Recovery System (WRS) Rack #2, WRS Rack #1, and Oxygen Generation System (OGS) rack are shown. The WRS provides clean water through the reclamation of wastewaters and is comprised of a Urine Processor Assembly (UPA) and a Water Processor Assembly (WPA). The UPA accepts and processes pretreated crewmember urine to allow it to be processed along with other wastewaters in the WPA. The WPA removes free gas, organic, and nonorganic constituents before the water goes through a series of multifiltration beds for further purification. The OGS produces oxygen for breathing air for the crew and laboratory animals, as well as for replacing oxygen loss. The OGS is comprised of a cell stack, which electrolyzes (breaks apart the hydrogen and oxygen molecules) some of the clean water provided by the WRS, and the separators that remove the gases from the water after electrolysis.

Process for light-driven hydrocarbon oxidation at ambient temperatures

DOEpatents

Shelnutt, John A.

1990-01-01

A photochemical reaction for the oxidation of hydrocarbons uses molecular oxygen as the oxidant. A reductive photoredox cycle that uses a tin(IV)- or antimony(V)-porphyrin photosensitizer generates the reducing equivalents required to activate oxygen. This artificial photosynthesis system drives a catalytic cycle, which mimics the cytochrome P.sub.450 reaction, to oxidize hydrocarbons. An iron(III)- or manganese(III)-porphyrin is used as the hydrocarbon-oxidation catalyst. Methylviologen can be used as a redox relay molecule to provide for electron-transfer from the reduced photosensitizer to the Fe or Mn porphyrin. The system is long-lived and may be used in photo-initiated spectroscopic studies of the reaction to determine reaction rates and intermediates.

CSTI Earth-to-orbit propulsion research and technology program overview

NASA Technical Reports Server (NTRS)

Gentz, Steven J.

1993-01-01

NASA supports a vigorous Earth-to-orbit (ETO) research and technology program as part of its Civil Space Technology Initiative. The purpose of this program is to provide an up-to-date technology base to support future space transportation needs for a new generation of lower cost, operationally efficient, long-lived and highly reliable ETO propulsion systems by enhancing the knowledge, understanding and design methodology applicable to advanced oxygen/hydrogen and oxygen/hydrocarbon ETO propulsion systems. Program areas of interest include analytical models, advanced component technology, instrumentation, and validation/verification testing. Organizationally, the program is divided between technology acquisition and technology verification as follows: (1) technology acquisition; and (2) technology verification.

Critical role for mesoscale eddy diffusion in supplying oxygen to hypoxic ocean waters

NASA Astrophysics Data System (ADS)

Gnanadesikan, Anand; Bianchi, Daniele; Pradal, Marie-Aude

2013-10-01

of the oceanic lateral eddy diffusion coefficient Aredi vary by more than an order of magnitude, ranging from less than a few hundred m2/s to thousands of m2/s. This uncertainty has first-order implications for the intensity of oceanic hypoxia, which is poorly simulated by the current generation of Earth System Models. Using satellite-based estimate of oxygen consumption in hypoxic waters to estimate the required diffusion coefficient for these waters gives a value of order 1000 m2/s. Varying Aredi across a suite of Earth System Models yields a broadly consistent result given a thermocline diapycnal diffusion coefficient of 1 × 10-5 m2/s.

Simultaneous nitrification, denitrification, and phosphorus removal in single-tank low-dissolved-oxygen systems under cyclic aeration.

PubMed

Ju, Lu-Kwang; Huang, Lin; Trivedi, Hiren

2007-08-01

Simultaneous nitrification and denitrification (SND or SNdN) may occur at low dissolved oxygen concentrations. In this study, bench-scale (approximately 6 L) bioreactors treating a continuous feed of synthetic wastewater were used to evaluate the effects of solids retention time and low dissolved oxygen concentration, under cyclic aeration, on the removal of organics, nitrogen, and phosphorus. The cyclic aeration was carried out with repeated cycles of 1 hour at a higher dissolved oxygen concentration (HDO) and 30 minutes at a lower (or zero) dissolved oxygen concentration (LDO). Compared with aeration at constant dissolved oxygen concentrations, the cyclic aeration, when operated with proper combinations of HDO and LDO, produced better-settling sludge and more complete nitrogen and phosphorus removal. For nitrogen removal, the advantage resulted from the more readily available nitrate and nitrite (generated by nitrification during the HDO period) for denitrification (during the LDO period). For phosphorus removal, the advantage of cyclic aeration came from the development of a higher population of polyphosphate-accumulating organisms, as indicated by the higher phosphorus contents in the sludge solids of the cyclically aerated systems. Nitrite shunt was also observed to occur in the LDO systems. Higher ratios of nitrite to nitrate were found in the systems of lower HDO (and, to less dependency, higher LDO), suggesting that the nitrite shunt took place mainly because of the disrupted nitrification at lower HDO. The study results indicated that the HDO used should be kept reasonably high (approximately 0.8 mg/L) or the HDO period prolonged, to promote adequate nitrification, and the LDO kept low (< or =0.2 mg/L), to achieve more complete denitrification and higher phosphorus removal. The above findings in the laboratory systems find strong support from the results obtained in full-scale plant implementation. Two plant case studies using the cyclic low-dissolved-oxygen aeration for creating and maintaining SND are also presented.

STS-84 oxygen generator for Mir on display at SPACEHAB

NASA Technical Reports Server (NTRS)

1997-01-01

Representatives of RSC Energia in Russia and other onlookers in the SPACEHAB Payload Processing Facility examine an oxygen generator which the Space Shuttle Atlantis will carry to the Russian Mir Space Station on Mission STS-84. Sergei Romanov, second from right in the white shirt, is the spokesperson for generator manufacturer RSC Energia. The nearly 300-pound generator will be strapped down on the inside surface of a SPACEHAB Double Module for the trip to Mir. It will replace one of two Mir units that have been malfunctioning recently. The generator functions by electrolysis, which separates water into its oxygen and hydrogen components. The hydrogen is vented and the oxygen is used for breathing by the Mir crew. The generator is 4.2 feet in length and 1.4 feet in diameter. STS-84, which is planned to include a Mir crew exchange of astronaut C. Michael Foale for Jerry M. Linenger, is targeted for a May 15 liftoff. It will be the sixth Shuttle-Mir docking.

Generator configuration for solid oxide fuel cells

DOEpatents

Reichner, Philip

1989-01-01

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

Developing Standards to Qualify a Fine Water Mist Fire Extinguisher for Human Spaceflight

NASA Technical Reports Server (NTRS)

Graf, John

2011-01-01

NASA is developing a Fine Water Mist Portable Fire Extinguisher for use on the International Space Station. The International Space Station presently uses two different types of fire extinguishers: a water foam extinguisher in the Russian Segment, and a carbon dioxide extinguisher in the US Segment and Columbus and Kibo pressurized elements. Changes in emergency breathing equipment make Fine Water Mist operationally preferable. Supplied oxygen breathing systems allow for safe discharge of a carbon dioxide fire extinguisher, without concerns of the crew inhaling unsafe levels of carbon dioxide. But the Portable Breathing Apparatus offers no more than 15 minutes of capability, and continued use of hose based supplied oxygen systems increases the oxygen content in a fire situation. NASA has developed a filtering respirator cartridge for use in a fire environment. It is qualified to provide up to 90 minutes of capability, and because it is a filtering respirator it does not add oxygen to the environment. The fire response respirator cartridge does not filter carbon dioxide, so a crew member discharging a CO2 fire extinguisher while wearing this filtering respirator would be at risk of inhaling unsafe levels of CO2. Fine Water Mist extinguishes a fire without creating a large volume of air with reduced oxygen and elevated CO2. Compared to the carbon dioxide based Portable Fire Extinguisher, the flight qualification of Fine Water Mist systems requires special care. Qualification of the CO2 based Portable Fire Extinguisher began with the assumption that any fire on ISS would be extinguished if the air in the fire environment reached a critical concentration of CO2. Qualification of a CO2 based system requires the developers to make assertions and assumptions about vehicle geometry and the ability of the extinguisher to deliver CO2 in different geometric configurations, but the developers did not need to make assertions or assumptions about the size of the fire, the temperature, or the heat generation rate. Fine Water Mist systems extinguish a fire predominantly by removing heat -- so qualification standards must evaluate geometry, but also temperature, heat transfer, and heat generation rate. This paper outlines and describes the methods used to develop standards used to qualify Fine Water Mist systems for a human spaceflight environment.

System Regulates the Water Contents of Fuel-Cell Streams

NASA Technical Reports Server (NTRS)

Vasquez, Arturo; Lazaroff, Scott

2005-01-01

An assembly of devices provides for both humidification of the reactant gas streams of a fuel cell and removal of the product water (the water generated by operation of the fuel cell). The assembly includes externally-sensing forward-pressure regulators that supply reactant gases (fuel and oxygen) at variable pressures to ejector reactant pumps. The ejector supply pressures depend on the consumption flows. The ejectors develop differential pressures approximately proportional to the consumption flow rates at constant system pressure and with constant flow restriction between the mixer-outlet and suction ports of the ejectors. For removal of product water from the circulating oxygen stream, the assembly includes a water/gas separator that contains hydrophobic and hydrophilic membranes. The water separator imposes an approximately constant flow restriction, regardless of the quality of the two-phase flow that enters it from the fuel cell. The gas leaving the water separator is nearly 100 percent humid. This gas is returned to the inlet of the fuel cell along with a quantity of dry incoming oxygen, via the oxygen ejector, thereby providing some humidification.

Potential of Organic Matrix Composites for Liquid Oxygen Tank

NASA Technical Reports Server (NTRS)

Davis, Samuel E.; Herald, Stephen D.; Stolzfus, Joel M.; Engel, Carl D.; Bohlen, James W.; Palm, Tod; Robinson, Michael J.

2005-01-01

Composite materials are being considered for the tankage of cryogenic propellants in access to space because of potentially lower structural weights. A major hurdle for composites is an inherent concern about the safety of using flammable structural materials in contact with liquid and gaseous oxygen. A hazards analysis approach addresses a series of specific concerns that must be addressed based upon test data. Under the 2nd Generation Reusable Launch Vehicle contracts, testing was begun for a variety of organic matrix composite materials both to aid in the selection of materials and to provide needed test data to support hazards analyses. The work has continued at NASA MSFC and the NASA WSTF to provide information on the potential for using composite materials in oxygen systems. Appropriate methods for oxygen compatibility testing of structural materials and data for a range of composite materials from impact, friction, flammability and electrostatic discharge testing are presented. Remaining concerns and conclusions about composite tank structures, and recommendations for additional testing are discussed. Requirements for system specific hazards analysis are identified.

CD73 and AMPD3 deficiency enhance metabolic performance via erythrocyte ATP that decreases hemoglobin oxygen affinity.

PubMed

O'Brien, William G; Berka, Vladimir; Tsai, Ah-Lim; Zhao, Zhaoyang; Lee, Cheng Chi

2015-08-07

Erythrocytes are the key target in 5'-AMP induced hypometabolism. To understand how regulation of endogenous erythrocyte AMP levels modulates systemic metabolism, we generated mice deficient in both CD73 and AMPD3, the key catabolic enzymes for extracellular and intra-erythrocyte AMP, respectively. Under physiological conditions, these mice displayed enhanced capacity for physical activity accompanied by significantly higher food and oxygen consumption, compared to wild type mice. Erythrocytes from Ampd3(-/-) mice exhibited higher half-saturation pressure of oxygen (p50) and about 3-fold higher levels of ATP and ADP, while they maintained normal 2,3-bisphosphoglycerate (2,3-BPG), methemoglobin levels and intracellular pH. The affinity of mammalian hemoglobin for oxygen is thought to be regulated primarily by 2,3-BPG levels and pH (the Bohr effect). However, our results show that increased endogenous levels of ATP and ADP, but not AMP, directly increase the p50 value of hemoglobin. Additionally, the rise in erythrocyte p50 directly correlates with an enhanced capability of systemic metabolism.

Fractional capacity electrolyzer development for CO2 and H2O electrolysis

NASA Technical Reports Server (NTRS)

Wynveen, R. A.

1980-01-01

The electrolyzer module was designed to produce 0.24 kg/d (0.53 lb/d) of breathable oxygen from the electrolysis of metabolic carbon dioxide and water vapor. The fractional capacity electrolyzer module is constructed from three electrochemical tube cells and contains only three critical seals. The module design illustrated an 84 percent reduction in the total number of seals for a one person capacity oxygen generating system based on the solid electrolyte carbon dioxide and water vapor electrolysis concept. The electrolyzer module was successfully endurance tested for 71 days.

Photodynamic activity of pyropheophorbide methyl ester and pyropheophorbide a in dimethylformamide solution.

PubMed

Al-Omari, Saleh; Ali, Ahmad

2009-03-01

Comparative spectroscopic study including the photosensitizers of pyropheophorbide methyl ester (PPME) and pyropheophorbide a (PPa) was performed to study their photodynamic activity. The investigated photosensitizers in a homogeneous system of dimethylformamide (DMF) are not photostable upon irradiation. The photobleaching efficiency of PPa is higher than that of PPME. Combining these results with the data obtained by measuring the singlet oxygen quantum yield and the hydroxyl group generation, it was revealed that the photobleaching efficiency could be correlated with the singlet oxygen quantum yield and the hydroxyl group production of the photosensitizer.

MHD performance calculations with oxygen enrichment

NASA Technical Reports Server (NTRS)

Pian, C. C. P.; Staiger, P. J.; Seikel, G. R.

1979-01-01

The impact of oxygen enrichment of the combustion air on the generator and overall plant performance was studied for the ECAS-scale MHD/steam plants. A channel optimization technique is described and the results of generator performance calculations using this technique are presented. Performance maps were generated to assess the impact of various generator parameters. Directly and separately preheated plant performance with varying O2 enrichment was calculated. The optimal level of enrichment was a function of plant type and preheat temperature. The sensitivity of overall plant performance to critical channel assumptions and oxygen plant performance characteristics was also examined.

Evaluation of Oxygen Concentrators and Chemical Oxygen Generators at Altitude and Temperature Extremes

DTIC Science & Technology

2015-04-22

ceased. Oxygen concentration was continuously measured with a fast laser diode oxygen analyzer (O2CAP, Oxigraf, Inc., Mountain View, CA) throughout the...duration of operation. The output generated from the COGs was analyzed by a gas mass spectrometer (QGA model HAS 301, Hiden Analytical, Livonia, MI...throughout the range of bolus volumes with each device at respiratory rates of 20 and 30 breaths /min with each bolus setting. Data were recorded every

Dependence of Ozone Generation on Gas Temperature Distribution in AC Atmospheric Pressure Dielectric Barrier Discharge in Oxygen

NASA Astrophysics Data System (ADS)

Takahashi, Go; Akashi, Haruaki

AC atmospheric pressure multi-filament dielectric barrier discharge in oxygen has been simulated using two dimensional fluid model. In the discharge, three kinds of streamers have been obtained. They are primary streamers, small scale streamers and secondary streamers. The primary streamers are main streamers in the discharge and the small scale streamers are formed after the ceasing of the primary streamers. And the secondary streamers are formed on the trace of the primary streamers. In these streamers, the primary and the small scale streamers are very effective to generate O(3P) oxygen atoms which are precursor of ozone. And the ozone is generated mainly in the vicinity of the dielectrics. In high gas temperature region, ozone generation decreases in general. However, increase of the O(3P) oxygen atom density in high gas temperature region compensates decrease of ozone generation rate coefficient. As a result, amount of ozone generation has not changed. But if the effect of gas temperature was neglected, amount of ozone generation increases 10%.

Comparison of hydrogen production and electrical power generation for energy capture in closed-loop ammonium bicarbonate reverse electrodialysis systems.

PubMed

Hatzell, Marta C; Ivanov, Ivan; Cusick, Roland D; Zhu, Xiuping; Logan, Bruce E

2014-01-28

Currently, there is an enormous amount of energy available from salinity gradients, which could be used for clean hydrogen production. Through the use of a favorable oxygen reduction reaction (ORR) cathode, the projected electrical energy generated by a single pass ammonium bicarbonate reverse electrodialysis (RED) system approached 78 W h m(-3). However, if RED is operated with the less favorable (higher overpotential) hydrogen evolution electrode and hydrogen gas is harvested, the energy recovered increases by as much ~1.5× to 118 W h m(-3). Indirect hydrogen production through coupling an RED stack with an external electrolysis system was only projected to achieve 35 W h m(-3) or ~1/3 of that produced through direct hydrogen generation.

75 FR 71536 - Airworthiness Directives; SOCATA Model TBM 700 Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2010-11-24

... difficulties for the pilot to release oxygen. After investigation it was found that, due to the design of the oxygen generator release pin, one of the mask's lanyard linked to the pin could be jammed when it is... procedure due to decompression, to a risk of generator fault with subsequent lack of oxygen on crew and/or...

75 FR 52480 - Airworthiness Directives; SOCATA Model TBM 700 Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-26

... difficulties for the pilot to release oxygen. After investigation it was found that, due to the design of the oxygen generator release pin, one of the mask's lanyard linked to the pin could be jammed when it is... procedure due to decompression, to a risk of generator fault with subsequent lack of oxygen on crew and/or...

Multi-generation chemical aging of α-pinene ozonolysis products by reactions with OH

NASA Astrophysics Data System (ADS)

Wang, Ningxin; Kostenidou, Evangelia; Donahue, Neil M.; Pandis, Spyros N.

2018-03-01

Secondary organic aerosol (SOA) formation from volatile organic compounds (VOCs) in the atmosphere can be thought of as a succession of oxidation steps. The production of later-generation SOA via continued oxidation of the first-generation products is defined as chemical aging. This study investigates aging in the α-pinene ozonolysis system with hydroxyl radicals (OH) through smog chamber experiments. The first-generation α-pinene ozonolysis products were allowed to react further with OH formed via HONO photolysis. After an equivalent of 2-4 days of typical atmospheric oxidation conditions, homogeneous OH oxidation of the α-pinene ozonolysis products resulted in a 20-40 % net increase in the SOA for the experimental conditions used in this work. A more oxygenated product distribution was observed after aging based on the increase in aerosol atomic oxygen-to-carbon ratio (O : C) by up to 0.04. Experiments performed at intermediate relative humidity (RH) of 50 % showed no significant difference in additional SOA formation during aging compared to those performed at a low RH of less than 20 %.

Design of Plant Gas Exchange Experiments in a Variable Pressure Growth Chamber

NASA Technical Reports Server (NTRS)

Corey, Kenneth A.

1996-01-01

Sustainable human presence in extreme environments such as lunar and martian bases will require bioregenerative components to human life support systems where plants are used for generation of oxygen, food, and water. Reduced atmospheric pressures will be used to minimize mass and engineering requirements. Few studies have assessed the metabolic and developmental responses of plants to reduced pressure and varied oxygen atmospheres. The first tests of hypobaric pressures on plant gas exchange and biomass production at the Johnson Space Center will be initiated in January 1996 in the Variable Pressure Growth Chamber (VPGC), a large, closed plant growth chamber rated for 10.2 psi. Experiments were designed and protocols detailed for two complete growouts each of lettuce and wheat to generate a general database for human life support requirements and to answer questions about plant growth processes in reduced pressure and varied oxygen environments. The central objective of crop growth studies in the VPGC is to determine the influence of reduced pressure and reduced oxygen on the rates of photosynthesis, dark respiration, evapotranspiration and biomass production of lettuce and wheat. Due to the constraint of one experimental unit, internal controls, called pressure transients, will be used to evaluate rates of CO2 uptake, O2 evolution, and H2O generation. Pressure transients will give interpretive power to the results of repeated growouts at both reduced and ambient pressures. Other experiments involve the generation of response functions to partial pressures of O2 and CO2 and to light intensity. Protocol for determining and calculating rates of gas exchange have been detailed. In order to build these databases and implement the necessary treatment combinations in short time periods, specific requirements for gas injections and removals have been defined. A set of system capability checks will include determination of leakage rates conducted prior to the actual crop growouts. Schedules of experimental events for lettuce and wheat are outlined and include replications in time of diurnal routines, pressure transients, variable pO2, pO2/pCO2 ratio, and light intensity responses.

Exposure of vitamins to UVB and UVA radiation generates singlet oxygen.

PubMed

Knak, Alena; Regensburger, Johannes; Maisch, Tim; Bäumler, Wolfgang

2014-05-01

Deleterious effects of UV radiation in tissue are usually attributed to different mechanisms. Absorption of UVB radiation in cell constituents like DNA causes photochemical reactions. Absorption of UVA radiation in endogenous photosensitizers like vitamins generates singlet oxygen via photosensitized reactions. We investigated two further mechanisms that might be involved in UV mediated cell tissue damage. Firstly, UVB radiation and vitamins also generate singlet oxygen. Secondly, UVB radiation may change the chemical structure of vitamins that may change the role of such endogenous photosensitizers in UVA mediated mechanisms. Vitamins were irradiated in solution using monochromatic UVB (308 nm) or UVA (330, 355, or 370 nm) radiation. Singlet oxygen was directly detected and quantified by its luminescence at 1270 nm. All investigated molecules generated singlet oxygen with a quantum yield ranging from 0.007 (vitamin D3) to 0.64 (nicotinamide) independent of the excitation wavelength. Moreover, pre-irradiation of vitamins with UVB changed their absorption in the UVB and UVA spectral range. Subsequently, molecules such as vitamin E and vitamin K1, which normally exhibit no singlet oxygen generation in the UVA, now produce singlet oxygen when exposed to UVA at 355 nm. This interplay of different UV sources is inevitable when applying serial or parallel irradiation with UVA and UVB in experiments in vitro. These results should be of particular importance for parallel irradiation with UVA and UVB in vivo, e.g. when exposing the skin to solar radiation.

Cerebral Microcirculation and Oxygen Tension in the Human Secondary Cortex

PubMed Central

Linninger, A. A.; Gould, I. G.; Marinnan, T.; Hsu, C.-Y.; Chojecki, M.; Alaraj, A.

2013-01-01

The three-dimensional spatial arrangement of the cortical microcirculatory system is critical for understanding oxygen exchange between blood vessels and brain cells. A three-dimensional computer model of a 3 × 3 × 3 mm3 subsection of the human secondary cortex was constructed to quantify oxygen advection in the microcirculation, tissue oxygen perfusion, and consumption in the human cortex. This computer model accounts for all arterial, capillary and venous blood vessels of the cerebral microvascular bed as well as brain tissue occupying the extravascular space. Microvessels were assembled with optimization algorithms emulating angiogenic growth; a realistic capillary bed was built with space filling procedures. The extravascular tissue was modeled as a porous medium supplied with oxygen by advection–diffusion to match normal metabolic oxygen demand. The resulting synthetic computer generated network matches prior measured morphometrics and fractal patterns of the cortical microvasculature. This morphologically accurate, physiologically consistent, multi-scale computer network of the cerebral microcirculation predicts the oxygen exchange of cortical blood vessels with the surrounding gray matter. Oxygen tension subject to blood pressure and flow conditions were computed and validated for the blood as well as brain tissue. Oxygen gradients along arterioles, capillaries and veins agreed with in vivo trends observed recently in imaging studies within experimental tolerances and uncertainty. PMID:23842693

Femtosecond, two-photon laser-induced-fluorescence imaging of atomic oxygen in an atmospheric-pressure plasma jet

NASA Astrophysics Data System (ADS)

Schmidt, Jacob B.; Sands, Brian L.; Kulatilaka, Waruna D.; Roy, Sukesh; Scofield, James; Gord, James R.

2015-06-01

Femtosecond, two-photon-absorption laser-induced-fluorescence (fs-TALIF) spectroscopy is employed to measure space- and time-resolved atomic-oxygen distributions in a nanosecond, repetitively pulsed, externally grounded, atmospheric-pressure plasma jet flowing helium with a variable oxygen admixture. The high-peak-intensity, low-average-energy femtosecond pulses result in increased TALIF signal with reduced photolytic inferences. This allows 2D imaging of absolute atomic-oxygen number densities ranging from 5.8   ×   1015 to 2.0   ×   1012cm-3 using a cooled CCD with an external intensifier. Xenon is used for signal and imaging-system calibrations to quantify the atomic-oxygen fluorescence signal. Initial results highlight a transition in discharge morphology from annular to filamentary, corresponding with a change in plasma chemistry from ozone to atomic oxygen production, as the concentration of oxygen in the feed gas is changed at a fixed voltage-pulse-repetition rate. In this configuration, significant concentrations of reactive oxygen species may be remotely generated by sustaining an active discharge beyond the confines of the dielectric capillary, which may benefit applications that require large concentrations of reactive oxygen species such as material processing or biomedical devices.

Nitrogen spark denoxer

DOEpatents

Ng, Henry K.; Novick, Vincent J.; Sekar, Ramanujam R.

1997-01-01

A NO.sub.X control system for an internal combustion engine includes an oxygen enrichment device that produces oxygen and nitrogen enriched air. The nitrogen enriched air contains molecular nitrogen that is provided to a spark plug that is mounted in an exhaust outlet of an internal combustion engine. As the nitrogen enriched air is expelled at the spark gap of the spark plug, the nitrogen enriched air is exposed to a pulsating spark that is generated across the spark gap of the spark plug. The spark gap is elongated so that a sufficient amount of atomic nitrogen is produced and is injected into the exhaust of the internal combustion engine. The injection of the atomic nitrogen into the exhaust of the internal combustion engine causes the oxides of nitrogen to be reduced into nitrogen and oxygen such that the emissions from the engine will have acceptable levels of NO.sub.X. The oxygen enrichment device that produces both the oxygen and nitrogen enriched air can include a selectively permeable membrane.

Atomic Oxygen Treatment as a Method of Recovering Smoke Damaged Paintings

NASA Technical Reports Server (NTRS)

Rutledge, Sharon K.; Banks, Bruce A.; Forkapa, Mark; Stueber, Thomas; Sechkar, Edward; Malinowski, Kevin

1998-01-01

Smoke damage, as a result of a fire, can be difficult to remove from some types of painting media without causing swelling, leaching or pigment movement or removal. A non-contact technique has been developed which can remove soot from the surface of a painting by use of a gently flowing gas containing atomic oxygen. The atomic oxygen chemically reacts with the soot on the surface creating gasses such as carbon monoxide and carbon dioxide which can be removed through the use of an exhaust system. The reaction is limited to the surface so that the process can be timed to stop when the paint layer is reached. Atomic oxygen is a primary component of the low Earth orbital environment, but can be generated on Earth through various methods. This paper will discuss the results of atomic oxygen treatment of soot exposed acrylic gesso, ink on paper, and a varnished oil painting. Reflectance measurements were used to characterize the surfaces before and after treatment.

Oxygen and Oxygen Toxicity: The Birth of Concepts

PubMed Central

Zhu, Hong; Traore, Kassim; Santo, Arben; Trush, Michael A.; Li, Y. Robert

2018-01-01

Molecular dioxygen (O2) is an essential element of aerobic life, yet incomplete reduction or excitation of O2 during aerobic metabolisms generates diverse oxygen-containing reactive species, commonly known as reactive oxygen species (ROS). On the one hand, ROS pose a serious threat to aerobic organisms via inducing oxidative damage to cellular constituents. On the other hand, these reactive species, when their generation is under homeostatic control, also play important physiological roles (e.g., constituting an important component of immunity and participating in redox signaling). This article defines oxygen and the key facts about oxygen, and discusses the relationship between oxygen and the emergence of early animals on Earth. The article then describes the discovery of oxygen by three historical figures and examines the birth of the concepts of oxygen toxicity and the underlying free radical mechanisms. The article ends with a brief introduction to the emerging field of ROS-mediated redox signaling and physiological responses. PMID:29707642

Comparing the efficiency of supersonic oxygen-iodine laser with different mixing designs

NASA Astrophysics Data System (ADS)

Vyskubenko, Boris A.; Adamenkov, A. A.; Bakshin, V. V.; Efremov, V. I.; Ilyin, S. P.; Kolobyanin, Yu. V.; Krukovsky, I. M.; Kudryashov, E. A.; Moiseyev, V. B.

2003-11-01

The paper presents experimental studies of supersonic oxygen-iodine laser (OIL) using twisted-flow singlet oxygen generator (SOG) over a wide range of the singlet oxygen pressures and the buffer gas flow rates. The experiments used different designs of the nozzle unit and mixing system for singlet oxygen and iodine gas with the carrier gas (such as nitrogen or helium). For a wide range of the key parameters, the study looked at the efficiency of supersonic OIL with variation of the singlet oxygen pressure. The measurements were made for different positions of the iodine injection plane with respect to the critical cross-section (both in the subsonic part of the nozzle and in the supersonic flow). The gas pressure at the nozzle unit entry was varied from 50 to 250 Torr. The total pressure loss have been found for different mixing designs. Experimental curves are given for energy performance and chemical efficiency of the supersonic OIL as a function of the key parameters. Comparison is made between the calculated and experimental data. For the optimum conditions of OIL operation, chemical efficiency of 25-30% has been achieved.

International Space Station United States Oxygen Generator Development Testing

NASA Technical Reports Server (NTRS)

Erickson, Robert J.; Mason, Richard K.

2000-01-01

A life test of a liquid anode feed oxygen generator assembly (OGA) using SPE(R) (United Technologies Corporation, Hamilton Sundstrand Division) membrane technology was terminated in June of 1999. In the total 15,658 hours of operation at MSFC since delivery in 1995, the OGA has produced 2,103 kilograms (kg) (4,632 pounds mass (lbm)) of oxygen, and 263 kg (579 lbm) of hydrogen. Evaluation of cell stack characteristics and oxygen and hydrogen hydrophilic/hydrophobic membrane separators will be discussed.

Oxygen-iodine ejector laser with a centrifugal bubbling singlet-oxygen generator

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

Zagidullin, M V; Nikolaev, V D; Svistun, M I

2005-10-31

It is shown that if a supersonic oxygen-iodine ejector laser is fed by singlet oxygen from a centrifugal bubbling generator operating at a centrifugal acceleration of {approx}400g, the laser output power achieves a value 1264 W at a chemical efficiency of 24.6% for an alkaline hydrogen peroxide flow rate of 208 cm{sup 3}s{sup -1} and a specific chlorine load of 1.34 mmol s{sup -1} per square centimetre of the bubble layer. (lasers)

ssDNA damage dependence from singlet oxygen concentration at photodynamic interaction

NASA Astrophysics Data System (ADS)

Klimenko, V. V.; Kaydanov, N. E.; Emelyanov, A. K.; Bogdanov, A. A.

2017-11-01

Single stranded DNA damage at photodynamic treatment with Radachlorin photosensitizer was investigated. Chemical trap method was used to evaluate generation of singlet oxygen in water solution. Interaction of singlet oxygen with ssDNA resulted into decrease of the replication activity of ssDNA. DNA stopped replicating during PCR at irradiation doses greater than 15 J/cm2 and concentration of photosensitizer [PS] = 3.8 μM. The dependence of replication activity of ssDNA on generated singlet oxygen concentration was identified.

Environmental Control and Life Support System

NASA Technical Reports Server (NTRS)

Ray, Charles; Adams, Alan

1990-01-01

Viewgraphs on the Environmental Control and Life Support System (ECLSS) for the space station are presented. The ECLSS is divided into six subsystems: temperature and humidity control (THC), atmosphere control and supply (ACS), atmosphere revitalization (AR), fire detection and suppression (FDS), water recovery management (WRM), and waste management (WM). Topics covered include: ECLSS subsystem functions; ECLSS distributed system; ECLSS functional distribution; CO2 removal; CO2 reduction; oxygen generation; urine processor; and potable water recovery.

Advanced oxygen-hydrocarbon rocket engine study

NASA Technical Reports Server (NTRS)

Obrien, C. J.; Salkeld, R.

1980-01-01

The advantages and disadvantages, system performance and operating limits, engine parametric data, and technology requirements for candidate high pressure LO2/Hydrocarbon engine systems are summarized. These summaries of parametric analysis and design provide a consistent engine system data base. Power balance data were generated for the eleven engine cycles. Engine cycle rating parameters were established and the desired condition and the effect of the parameter on the engine and/or vehicle are described.

Perovskite electrodes and method of making the same

DOEpatents

Seabaugh, Matthew M [Columbus, OH; Swartz, Scott L [Columbus, OH

2009-09-22

The invention relates to perovskite oxide electrode materials in which one or more of the elements Mg, Ni, Cu, and Zn are present as minority components that enhance electrochemical performance, as well as electrode products with these compositions and methods of making the electrode materials. Such electrodes are useful in electrochemical system applications such as solid oxide fuel cells, ceramic oxygen generation systems, gas sensors, ceramic membrane reactors, and ceramic electrochemical gas separation systems.

Perovskite electrodes and method of making the same

DOEpatents

Seabaugh, Matthew M.; Swartz, Scott L.

2005-09-20

The invention relates to perovskite oxide electrode materials in which one or more of the elements Mg, Ni, Cu, and Zn are present as minority components that enhance electrochemical performance, as well as electrode products with these compositions and methods of making the electrode materials. Such electrodes are useful in electrochemical system applications such as solid oxide fuel cells, ceramic oxygen generation systems, gas sensors, ceramic membrane reactors, and ceramic electrochemical gas separation systems.

Singlet oxygen generation during the oxidation of L-tyrosine and L-dopa with mushroom tyrosinase.

PubMed

Miyaji, Akimitsu; Kohno, Masahiro; Inoue, Yoshihiro; Baba, Toshihide

2016-03-18

The generation of singlet oxygen during the oxidation of tyrosine and L-dopa using mushroom tyrosinase in a phosphate buffer (pH 7.4), the model of melanin synthesis in melanocytes, was examined. The reaction was performed in the presence of 2,2,6,6-tetramethyl-4-piperidone (4-oxo-TEMP), an acceptor of singlet oxygen and the electron spin resonance (ESR) of the spin adduct, 4-oxo-2,2,6,6-tetramethyl-1-piperidinyloxy (4-oxo-TEMPO), was measured. An increase in the ESR signal attributable to 4-oxo-TEMPO was observed during the oxidation of tyrosine and L-dopa with tyrosinase, indicating the generation of singlet oxygen. The results suggest that (1)O2 generation via tyrosinase-catalyzed melanin synthesis occurs in melanocyte. Copyright © 2016 Elsevier Inc. All rights reserved.

Parabanic acid is the singlet oxygen specific oxidation product of uric acid.

PubMed

Iida, Sayaka; Ohkubo, Yuki; Yamamoto, Yorihiro; Fujisawa, Akio

2017-11-01

Uric acid quenches singlet oxygen physically or reacts with it, but the oxidation product has not been previously characterized. The present study determined that the product is parabanic acid, which was confirmed by LC/TOFMS analysis. Parabanic acid was stable at acidic pH (<5.0), but hydrolyzed to oxaluric acid at neutral or alkaline pH. The total yields of parabanic acid and oxaluric acid based on consumed uric acid were ~100% in clean singlet oxygen production systems such as UVA irradiation of Rose Bengal and thermal decomposition of 3-(1,4-dihydro-1,4-epidioxy-4-methyl-1-naphthyl)propionic acid. However, the ratio of the amount of uric acid consumed to the total amount of singlet oxygen generated was less than 1/180, indicating that most of the singlet oxygen was physically quenched. The total yields of parabanic acid and oxaluric acid were high in the uric acid oxidation systems with hydrogen peroxide plus hypochlorite or peroxynitrite. They became less than a few percent in peroxyl radical-, hypochlorite- or peroxynitrite-induced oxidation of uric acid. These results suggest that parabanic acid could be an in vivo probe of singlet oxygen formation because of the wide distribution of uric acid in human tissues and extracellular spaces. In fact, sunlight exposure significantly increased human skin levels of parabanic acid.

Variable oxygen/nitrogen enriched intake air system for internal combustion engine applications

DOEpatents

Poola, Ramesh B.; Sekar, Ramanujam R.; Cole, Roger L.

1997-01-01

An air supply control system for selectively supplying ambient air, oxygen enriched air and nitrogen enriched air to an intake of an internal combustion engine includes an air mixing chamber that is in fluid communication with the air intake. At least a portion of the ambient air flowing to the mixing chamber is selectively diverted through a secondary path that includes a selectively permeable air separating membrane device due a differential pressure established across the air separating membrane. The permeable membrane device separates a portion of the nitrogen in the ambient air so that oxygen enriched air (permeate) and nitrogen enriched air (retentate) are produced. The oxygen enriched air and the nitrogen enriched air can be selectively supplied to the mixing chamber or expelled to atmosphere. Alternatively, a portion of the nitrogen enriched air can be supplied through another control valve to a monatomic-nitrogen plasma generator device so that atomic nitrogen produced from the nitrogen enriched air can be then injected into the exhaust of the engine. The oxygen enriched air or the nitrogen enriched air becomes mixed with the ambient air in the mixing chamber and then the mixed air is supplied to the intake of the engine. As a result, the air being supplied to the intake of the engine can be regulated with respect to the concentration of oxygen and/or nitrogen.

Power Balance and Impurity Studies in TCS

NASA Astrophysics Data System (ADS)

Grossnickle, J. A.; Pietrzyk, Z. A.; Vlases, G. C.

2003-10-01

A "zero-dimension" power balance model was developed based on measurements of absorbed power, radiated power, absolute D_α, temperature, and density for the TCS device. Radiation was determined to be the dominant source of power loss for medium to high density plasmas. The total radiated power was strongly correlated with the Oxygen line radiation. This suggests Oxygen is the dominant radiating species, which was confirmed by doping studies. These also extrapolate to a Carbon content below 1.5%. Determining the source of the impurities is an important question that must be answered for the TCS upgrade. Preliminary indications are that the primary sources of Oxygen are the stainless steel end cones. A Ti gettering system is being installed to reduce this Oxygen source. A field line code has been developed for use in tracking where open field lines terminate on the walls. Output from this code is also used to generate grids for an impurity tracking code.

Oxygen diffusion model of the mixed (U,Pu)O2 ± x: Assessment and application

NASA Astrophysics Data System (ADS)

Moore, Emily; Guéneau, Christine; Crocombette, Jean-Paul

2017-03-01

The uranium-plutonium (U,Pu)O2 ± x mixed oxide (MOX) is used as a nuclear fuel in some light water reactors and considered for future reactor generations. To gain insight into fuel restructuring, which occurs during the fuel lifetime as well as possible accident scenarios understanding of the thermodynamic and kinetic behavior is crucial. A comprehensive evaluation of thermo-kinetic properties is incorporated in a computational CALPHAD type model. The present DICTRA based model describes oxygen diffusion across the whole range of plutonium, uranium and oxygen compositions and temperatures by incorporating vacancy and interstitial migration pathways for oxygen. The self and chemical diffusion coefficients are assessed for the binary UO2 ± x and PuO2 - x systems and the description is extended to the ternary mixed oxide (U,Pu)O2 ± x by extrapolation. A simulation to validate the applicability of this model is considered.

Mitigating Hypoxic Stress on Pancreatic Islets via In situ Oxygen Generating Biomaterial

PubMed Central

Coronel, Maria M.; Geusz, Ryan; Stabler, Cherie L.

2017-01-01

A major obstacle in the survival and efficacy of tissue engineered transplants is inadequate oxygenation, whereby unsupportive oxygen tensions result in significant cellular dysfunction and death within the implant. In a previous report, we developed an innovative oxygen generating biomaterial, termed OxySite, to provide supportive in situ oxygenation to cells and prevent hypoxia-induced damage. Herein, we explored the capacity of this biomaterial to mitigate hypoxic stress in both rat and nonhuman primate pancreatic islets by decreasing cell death, supporting metabolic activity, sustaining aerobic metabolism, preserving glucose responsiveness, and decreasing the generation of inflammatory cytokines. Further, the impact of supplemental oxygenation on in vivo cell function was explored by the transplantation of islets previously co-cultured with OxySite into a diabetic rat model. Transplant outcomes revealed significant improvement in graft efficacy for OxySite-treated islets, when transplanted within an extrahepatic site. These results demonstrate the potency of the OxySite material to mitigate activation of detrimental hypoxia-induced pathways in islets during culture and highlights the importance of in situ oxygenation on resulting islet transplant outcomes. PMID:28342320

Technology advancement of the static feed water electrolysis process

NASA Technical Reports Server (NTRS)

Jensen, F. C.; Schubert, F. H.

1977-01-01

Some results are presented of a research and development program to continue the development of a method to generate oxygen for crew metabolic consumption during extended manned space flights. The concept being pursued is that of static feed water electrolysis. Specific major results of the work included: (1) completion of a 30-day electrode test using a Life Systems, Inc.-developed high performance catalyst. During startup the cell voltages were as low as 1.38 V at current densities of 108 mA/sq cm (100 ASF) and temperatures of 355 K (180 F). At the end of 30 days of testing the cell voltages were still only 1.42 V at 108 mA/sq cm, (2) determination that the Static Feed Water Electrolysis Module does not release an aerosol of the cell electrolyte into the product gas streams after a break-in period of 24 hours following a new electrolyte charge, and (3) completion of a detailed design analysis of an electrochemical Oxygen Generation Subsystem at a three-man level (4.19 kg/day (9.24 lb/day) of oxygen).

Complexing Methylene Blue with Phosphorus Dendrimers to Increase Photodynamic Activity.

PubMed

Dabrzalska, Monika; Janaszewska, Anna; Zablocka, Maria; Mignani, Serge; Majoral, Jean Pierre; Klajnert-Maculewicz, Barbara

2017-02-23

The efficiency of photodynamic therapy is limited mainly due to low selectivity, unfavorable biodistribution of photosensitizers, and long-lasting skin sensitivity to light. However, drug delivery systems based on nanoparticles may overcome the limitations mentioned above. Among others, dendrimers are particularly attractive as carriers, because of their globular architecture and high loading capacity. The goal of the study was to check whether an anionic phosphorus dendrimer is suitable as a carrier of a photosensitizer-methylene blue (MB). As a biological model, basal cell carcinoma cell lines were used. We checked the influence of the MB complexation on its singlet oxygen production ability using a commercial fluorescence probe. Next, cellular uptake, phototoxicity, reactive oxygen species (ROS) generation, and cell death were investigated. The MB-anionic dendrimer complex (MB-1an) was found to generate less singlet oxygen; however, the complex showed higher cellular uptake and phototoxicity against basal cell carcinoma cell lines, which was accompanied with enhanced ROS production. Owing to the obtained results, we conclude that the photodynamic activity of MB complexed with an anionic dendrimer is higher than free MB against basal cell carcinoma cell lines.

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

EPA Science Inventory

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

Coleman works at the AR OGS Rack in the Node 3

NASA Image and Video Library

2011-02-08

ISS026-E-025143 (8 Feb. 2011) --- NASA astronaut Catherine (Cady) Coleman, Expedition 26 flight engineer, works at the Atmosphere Revitalization / Oxygen Generation System (AR OGS) rack in the Harmony node of the International Space Station. Coleman collected recirculation loop samples for subsequent analysis for pH value.

Coleman works at the AR OGS Rack in the Node 3

NASA Image and Video Library

2011-02-08

ISS026-E-025142 (8 Feb. 2011) --- NASA astronaut Catherine (Cady) Coleman, Expedition 26 flight engineer, works at the Atmosphere Revitalization / Oxygen Generation System (AR OGS) rack in the Harmony node of the International Space Station. Coleman collected recirculation loop samples for subsequent analysis for pH value.

Evaluation of phototoxicity of dendritic porphyrin-based phosphorescent oxygen probes: an in vitro study†

PubMed Central

Lebedev, Artem Y.; Marchi, Enrico; Yuan, Min; Esipova, Tatiana V.; Bergamini, Giacomo; Wilson, David F.

2013-01-01

Biological oxygen measurements by phosphorescence quenching make use of exogenous phosphorescent probes, which are introduced directly into the medium of interest (e.g. blood or interstitial fluid) where they serve as molecular sensors for oxygen. The byproduct of the quenching reaction is singlet oxygen, a highly reactive species capable of damaging biological tissue. Consequently, potential probe phototoxicity is a concern for biological applications. Herein, we compared the ability of polyethyleneglycol (PEG)-coated Pd tetrabenzoporphyrin (PdTBP)-based dendritic nanoprobes of three successive generations to sensitize singlet oxygen. It was found that the size of the dendrimer has practically no effect on the singlet oxygen sensitization efficiency in spite of the strong attenuation of the triplet quenching rate with an increase in the dendrimer generation. This unexpected result is due to the fact that the lifetime of the PdTBP triplet state in the absence of oxygen increases with dendritic generation, thus compensating for the concomitant decrease in the rate of quenching. Nevertheless, in spite of their ability to sensitize singlet oxygen, the phosphorescent probes were found to be non-phototoxic when compared with the commonly used photodynamic drug Photofrin in a standard cell-survival assay. The lack of phototoxicity is presumably due to the inability of PEGylated probes to associate with cell surfaces and/or penetrate cellular membranes. In contrast, conventional photosensitizers bind to cell components and act by generating singlet oxygen inside or in the immediate vicinity of cellular organelles. Therefore, PEGylated dendritic probes are safe to use for tissue oxygen measurements as long as the light doses are less than or equal to those commonly employed in photodynamic therapy. PMID:21409208

Ethanol flame synthesis of carbon nanotubes in deficient oxygen environments

NASA Astrophysics Data System (ADS)

Hu, Wei-Chieh; Lin, Ta-Hui

2016-04-01

In this study, carbon nanotubes (CNTs) were synthesized using ethanol diffusion flames in a stagnation-flow system composed of an upper oxidizer duct and a lower liquid pool. In the experiments, a gaseous mixture of oxygen and nitrogen flowed from the upper oxidizer duct, and then impinged onto the vertically aligned ethanol pool to generate a planar and steady diffusion flame in a deficient oxygen environment. A nascent nickel mesh was used as the catalytic metal substrate to collect deposited materials. The effect of low oxygen concentration on the formation of CNTs was explored. The oxygen concentration significantly influenced the flame environment and thus the synthesized carbon products. Lowering the oxygen concentration increased the yield, diameter, and uniformity of CNTs. The optimal operating conditions for CNT synthesis were an oxygen concentration in the range of 15%-19%, a flame temperature in the range of 460 °C-870 °C, and a sampling position of 0.5-1 mm below the upper edge of the blue flame front. It is noteworthy that the concentration gradient of C2 species and CO governed the CNT growth directly. CNTs were successfully fabricated in regions with uniform C2 species and CO distributions.

Modeling and experimental methods to predict oxygen distribution in bone defects following cell transplantation.

PubMed

Heylman, Christopher M; Santoso, Sharon; Krebs, Melissa D; Saidel, Gerald M; Alsberg, Eben; Muschler, George F

2014-04-01

We have developed a mathematical model that allows simulation of oxygen distribution in a bone defect as a tool to explore the likely effects of local changes in cell concentration, defect size or geometry, local oxygen delivery with oxygen-generating biomaterials (OGBs), and changes in the rate of oxygen consumption by cells within a defect. Experimental data for the oxygen release rate from an OGB and the oxygen consumption rate of a transplanted cell population are incorporated into the model. With these data, model simulations allow prediction of spatiotemporal oxygen concentration within a given defect and the sensitivity of oxygen tension to changes in critical variables. This information may help to minimize the number of experiments in animal models that determine the optimal combinations of cells, scaffolds, and OGBs in the design of current and future bone regeneration strategies. Bone marrow-derived nucleated cell data suggest that oxygen consumption is dependent on oxygen concentration. OGB oxygen release is shown to be a time-dependent function that must be measured for accurate simulation. Simulations quantify the dependency of oxygen gradients in an avascular defect on cell concentration, cell oxygen consumption rate, OGB oxygen generation rate, and OGB geometry.

Oxygen Plasma Effect on QCM Sensor Coated Polystyrene Film

NASA Astrophysics Data System (ADS)

Khusnah, N. F.; Sakti, S. P.; Santjojo, D. J. D. H.

2018-05-01

Hydrophobicity property of polystyrene (PS) thin film is one of the essential factors to be considered in the development of quartz crystal microbalance (QCM) biosensor using polystyrene as matrix layer. Many methods were developed to improve the immobilization rate of the biomolecule on the sensor surface without affecting the QCM essential works. Surface modification of the sensor surface aims to modify the physical and or chemical property of the surface. A straightforward method, the fast, environmentally-friendly, and low-cost solution to modify the sensor surface coated with polystyrene film is using oxygen plasma. In this experiment, the polystyrene film was spin-coated on both surface of QCM electrodes and then heated at 100 °C. The specimen is then placed for 5 min long in a chamber filled with oxygen plasma generated by 2 MHz RF-DC high-density plasma system. The relationship between DC-bias used and the changes in morphology properties of the coated film was characterized by Topography Measurement System (TMS) and Contact Angle Measurement. The electrical characteristic of QCM was also characterized using Impedance Analyzer. It was revealed that the contact angle of oxygen plasma treated film is changed and depicted the hydrophobic character. Also, there is an increasing resonance frequency of the sensor after oxygen plasma treatment indicates an etching mechanism occurs during plasma treatment.

LOX Tank Helium Removal for Propellant Scavenging

NASA Technical Reports Server (NTRS)

Chato, David J.

2009-01-01

System studies have shown a significant advantage to reusing the hydrogen and oxygen left in these tanks after landing on the Moon in fuel cells to generate power and water for surface systems. However in the current lander concepts, the helium used to pressurize the oxygen tank can substantially degrade fuel cell power and water output by covering the reacting surface with inert gas. This presentation documents an experimental investigation of methods to remove the helium pressurant while minimizing the amount of the oxygen lost. This investigation demonstrated that significant quantities of Helium (greater than 90% mole fraction) remain in the tank after draining. Although a single vent cycle reduced the helium quantity, large amounts of helium remained. Cyclic venting appeared to be more effective. Three vent cycles were sufficient to reduce the helium to small (less than 0.2%) quantities. Two vent cycles may be sufficient since once the tank has been brought up to pressure after the second vent cycle the helium concentration has been reduced to the less than 0.2% level. The re-pressurization process seemed to contribute to diluting helium. This is as expected since in order to raise the pressure liquid oxygen must be evaporated. Estimated liquid oxygen loss is on the order of 82 pounds (assuming the third vent cycle is not required).

The role of singlet oxygen and oxygen concentration in photodynamic inactivation of bacteria

PubMed Central

Maisch, Tim; Baier, Jürgen; Franz, Barbara; Maier, Max; Landthaler, Michael; Szeimies, Rolf-Markus; Bäumler, Wolfgang

2007-01-01

New antibacterial strategies are required in view of the increasing resistance of bacteria to antibiotics. One promising technique involves the photodynamic inactivation of bacteria. Upon exposure to light, a photosensitizer in bacteria can generate singlet oxygen, which oxidizes proteins or lipids, leading to bacteria death. To elucidate the oxidative processes that occur during killing of bacteria, Staphylococcus aureus was incubated with a standard photosensitizer, and the generation and decay of singlet oxygen was detected directly by its luminescence at 1,270 nm. At low bacterial concentrations, the time-resolved luminescence of singlet oxygen showed a decay time of 6 ± 2 μs, which is an intermediate time for singlet oxygen decay in phospholipids of membranes (14 ± 2 μs) and in the surrounding water (3.5 ± 0.5 μs). Obviously, at low bacterial concentrations, singlet oxygen had sufficient access to water outside of S. aureus by diffusion. Thus, singlet oxygen seems to be generated in the outer cell wall areas or in adjacent cytoplasmic membranes of S. aureus. In addition, the detection of singlet oxygen luminescence can be used as a sensor of intracellular oxygen concentration. When singlet oxygen luminescence was measured at higher bacterial concentrations, the decay time increased significantly, up to ≈40 μs, because of oxygen depletion at these concentrations. This observation is an important indicator that oxygen supply is a crucial factor in the efficacy of photodynamic inactivation of bacteria, and will be of particular significance should this approach be used against multiresistant bacteria. PMID:17431036

Generation of nanobubbles by ceramic membrane filters: The dependence of bubble size and zeta potential on surface coating, pore size and injected gas pressure.

PubMed

Ahmed, Ahmed Khaled Abdella; Sun, Cuizhen; Hua, Likun; Zhang, Zhibin; Zhang, Yanhao; Zhang, Wen; Marhaba, Taha

2018-07-01

Generation of gaseous nanobubbles (NBs) by simple, efficient, and scalable methods is critical for industrialization and applications of nanobubbles. Traditional generation methods mainly rely on hydrodynamic, acoustic, particle, and optical cavitation. These generation processes render issues such as high energy consumption, non-flexibility, and complexity. This research investigated the use of tubular ceramic nanofiltration membranes to generate NBs in water with air, nitrogen and oxygen gases. This system injects pressurized gases through a tubular ceramic membrane with nanopores to create NBs. The effects of membrane pores size, surface energy, and the injected gas pressures on the bubble size and zeta potential were examined. The results show that the gas injection pressure had considerable effects on the bubble size, zeta potential, pH, and dissolved oxygen of the produced NBs. For example, increasing the injection air pressure from 69 kPa to 414 kPa, the air bubble size was reduced from 600 to 340 nm respectively. Membrane pores size and surface energy also had significant effects on sizes and zeta potentials of NBs. The results presented here aim to fill out the gaps of fundamental knowledge about NBs and development of efficient generation methods. Copyright © 2018 Elsevier Ltd. All rights reserved.

KSC-97pc675

NASA Image and Video Library

1997-04-19

KENNEDY SPACE CENTER, FLA. -- McDonnell Douglas-SPACEHAB technicians strap in place a Russian-made oxygen generator on the floor of a SPACEHAB Double Module, being prepared for flight in the SPACEHAB Payload Processing Facility. From left, are Mark Halavin and Marc Tuttle. The oxygen generator, manufactured in Russia by RSC Energia, will be carried aboard the Space Shuttle Atlantis on Mission STS-84 for the Shuttle’s scheduled docking with the Russian Space Station Mir next month. The nearly 300-pound generator will replace one of two Mir units that have been malfunctioning recently. The generator functions by electrolysis, which separates water into its oxygen and hydrogen components. The hydrogen is vented and the oxygen is used for breathing by the Mir crew. The generator is 4.2 feet in length and 1.4 feet in diameter. STS-84, which is planned to include a Mir crew exchange of astronaut C. Michael Foale for Jerry M. Linenger, is targeted for a May 15 liftoff. It will be the sixth Shuttle-Mir docking

Singlet oxygen generation as a major cause for parasitic reactions during cycling of aprotic lithium-oxygen batteries

NASA Astrophysics Data System (ADS)

Mahne, Nika; Schafzahl, Bettina; Leypold, Christian; Leypold, Mario; Grumm, Sandra; Leitgeb, Anita; Strohmeier, Gernot A.; Wilkening, Martin; Fontaine, Olivier; Kramer, Denis; Slugovc, Christian; Borisov, Sergey M.; Freunberger, Stefan A.

2017-03-01

Non-aqueous metal-oxygen batteries depend critically on the reversible formation/decomposition of metal oxides on cycling. Irreversible parasitic reactions cause poor rechargeability, efficiency, and cycle life, and have predominantly been ascribed to the reactivity of reduced oxygen species with cell components. These species, however, cannot fully explain the side reactions. Here we show that singlet oxygen forms at the cathode of a lithium-oxygen cell during discharge and from the onset of charge, and accounts for the majority of parasitic reaction products. The amount increases during discharge, early stages of charge, and charging at higher voltages, and is enhanced by the presence of trace water. Superoxide and peroxide appear to be involved in singlet oxygen generation. Singlet oxygen traps and quenchers can reduce parasitic reactions effectively. Awareness of the highly reactive singlet oxygen in non-aqueous metal-oxygen batteries gives a rationale for future research towards achieving highly reversible cell operation.

Designing a Microfluidic Device with Integrated Ratiometric Oxygen Sensors for the Long-Term Control and Monitoring of Chronic and Cyclic Hypoxia

PubMed Central

Grist, Samantha M.; Schmok, Jonathan C.; Liu, Meng-Chi (Andy); Chrostowski, Lukas; Cheung, Karen C.

2015-01-01

Control of oxygen over cell cultures in vitro is a topic of considerable interest, as chronic and cyclic hypoxia can alter cell behaviour. Both static and transient hypoxic levels have been found to affect tumour cell behaviour; it is potentially valuable to include these effects in early, in vitro stages of drug screening. A barrier to their inclusion is that rates of transient hypoxia can be a few cycles/hour, which is difficult to reproduce in traditional in vitro cell culture environments due to long diffusion distances from control gases to the cells. We use a gas-permeable three-layer microfluidic device to achieve spatial and temporal oxygen control with biologically-relevant switching times. We measure the oxygen profiles with integrated, ratiometric optical oxygen sensors, demonstrate sensor and system stability over multi-day experiments, and characterize a pre-bleaching process to improve sensor stability. We show, with both finite-element modelling and experimental data, excellent control over the oxygen levels by the device, independent of fluid flow rate and oxygenation for the operating flow regime. We measure equilibration times of approximately 10 min, generate complex, time-varying oxygen profiles, and study the effects of oxygenated media flow rates on the measured oxygen levels. This device could form a useful tool for future long-term studies of cell behaviour under hypoxia. PMID:26287202

Preliminary design of an auxiliary power unit for the space shuttle: Component and system configuration screening analysis

NASA Technical Reports Server (NTRS)

Binsley, R. L.; Maddox, J. P.; Marcy, R. D.; Siegler, R. S.; Spies, R.

1971-01-01

The auxiliary power unit (APU) for the space shuttle is required to provide hydraulic and electrical power on board the booster and orbiter vehicles. Five systems and their associated components, which utilize hot gas turbines to supply horsepower at gearbox output pads, were studied. Hydrogen-oxygen and storable propellants were considered for the hot gas supply. All APU's were required to be self-contained with respect to dissipating internally generated heat. These five systems were evaluated relative to a consistent criteria. The system supplied with high pressure gaseous hydrogen and oxygen was recommended as the best approach. It included a two-stage pressure-compounded partial-admission turbine, a propellant conditioning system with recuperation, a control system, and a gearbox. The gearbox output used was 240 hp. At the close of the study a 400 hp level was considered more appropriate for meeting the prime shuttle vehicle needs, and an in-depth analysis of the system at the 400 hp output level was recommended.

Low oxygen tension enhances endothelial fate of human pluripotent stem cells.

PubMed

Kusuma, Sravanti; Peijnenburg, Elizabeth; Patel, Parth; Gerecht, Sharon

2014-04-01

A critical regulator of the developing or regenerating vasculature is low oxygen tension. Precise elucidation of the role of low oxygen environments on endothelial commitment from human pluripotent stem cells necessitates controlled in vitro differentiation environments. We used a feeder-free, 2-dimensional differentiation system in which we could monitor accurately dissolved oxygen levels during human pluripotent stem cell differentiation toward early vascular cells (EVCs). We found that oxygen uptake rate of differentiating human pluripotent stem cells is lower in 5% O2 compared with atmospheric conditions. EVCs differentiated in 5% O2 had an increased vascular endothelial cadherin expression with clusters of vascular endothelial cadherin+ cells surrounded by platelet-derived growth factor β+ cells. When we assessed the temporal effects of low oxygen differentiation environments, we determined that low oxygen environments during the early stages of EVC differentiation enhance endothelial lineage commitment. EVCs differentiated in 5% O2 exhibited an increased expression of vascular endothelial cadherin and CD31 along with their localization to the membrane, enhanced lectin binding and acetylated low-density lipoprotein uptake, rapid cord-like structure formation, and increased expression of arterial endothelial cell markers. Inhibition of reactive oxygen species generation during the early stages of differentiation abrogated the endothelial inductive effects of the low oxygen environments. Low oxygen tension during early stages of EVC derivation induces endothelial commitment and maturation through the accumulation of reactive oxygen species, highlighting the importance of regulating oxygen tensions during human pluripotent stem cell-vascular differentiation.

Investigation of Radio Frequency Discharges and Langmuir Probe Diagnostic Methods in a Fast Flowing Electronegative Background Gas

DTIC Science & Technology

2007-12-01

Pinhero and others, 1998). The Air Force is currently developing the Electric Chemical Oxygen Iodine Laser (ElectriCOIL) system to replace the liquid...chemistry generator currently used in the Air Borne Laser (ABL) system (Zimmerman and others, 2003). The ElectriCOIL system produces in a radio...convected downstream is critical to improving the performance of the ABL system . The use of a second non-self sustained discharge operating at a lower

Method of producing gaseous products using a downflow reactor

DOEpatents

Cortright, Randy D; Rozmiarek, Robert T; Hornemann, Charles C

2014-09-16

Reactor systems and methods are provided for the catalytic conversion of liquid feedstocks to synthesis gases and other noncondensable gaseous products. The reactor systems include a heat exchange reactor configured to allow the liquid feedstock and gas product to flow concurrently in a downflow direction. The reactor systems and methods are particularly useful for producing hydrogen and light hydrocarbons from biomass-derived oxygenated hydrocarbons using aqueous phase reforming. The generated gases may find used as a fuel source for energy generation via PEM fuel cells, solid-oxide fuel cells, internal combustion engines, or gas turbine gensets, or used in other chemical processes to produce additional products. The gaseous products may also be collected for later use or distribution.

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

PubMed

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

2013-02-21

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

Development of a hybrid photo-bioreactor and nanoparticle adsorbent system for the removal of CO2, and selected organic and metal co-pollutants.

PubMed

Rocha, Andrea A; Wilde, Christian; Hu, Zhenzhong; Nepotchatykh, Oleg; Nazarenko, Yevgen; Ariya, Parisa A

2017-07-01

Fossil fuel combustion and many industrial processes generate gaseous emissions that contain a number of toxic organic pollutants and carbon dioxide (CO 2 ) which contribute to climate change and atmospheric pollution. There is a need for green and sustainable solutions to remove air pollutants, as opposed to conventional techniques which can be expensive, consume additional energy and generate further waste. We developed a novel integrated bioreactor combined with recyclable iron oxide nano/micro-particle adsorption interfaces, to remove CO 2, and undesired organic air pollutants using natural particles, while generating oxygen. This semi-continuous bench-scale photo-bioreactor was shown to successfully clean up simulated emission streams of up to 45% CO 2 with a conversion rate of approximately 4% CO 2 per hour, generating a steady supply of oxygen (6mmol/hr), while nanoparticles effectively remove several undesired organic by-products. We also showed algal waste of the bioreactor can be used for mercury remediation. We estimated the potential CO 2 emissions that could be captured from our new method for three industrial cases in which, coal, oil and natural gas were used. With a 30% carbon capture system, the reduction of CO 2 was estimated to decrease by about 420,000, 320,000 and 240,000 metric tonnes, respectively for a typical 500MW power plant. The cost analysis we conducted showed potential to scale-up, and the entire system is recyclable and sustainable. We further discuss the implications of usage of this complete system, or as individual units, that could provide a hybrid option to existing industrial setups. Copyright © 2016. Published by Elsevier B.V.

Effects of potassium iodide, colchicine and dapsone on the generation of polymorphonuclear leukocyte-derived oxygen intermediates.

PubMed

Miyachi, Y; Niwa, Y

1982-08-01

The effects of potassium iodide, colchicine and dapsone on the in vitro generation of polymorphonuclear leukocyte (PMN)-derived oxygen intermediates were investigated. These three drugs have beneficial effects on those conditions in which PMNs play an important pathogenetic role. Three oxygen intermediates, superoxide anion (O2-), hydrogen peroxide (H2O2), hydroxyl radical (OH.) and chemiluminescence were included in assay studies. Dose response studies were performed with therapeutic doses of the drugs (10 microM--mM). We found that both potassium iodide and dapsone significantly suppressed the generation of oxygen intermediates, except for O2-. Colchicine decreased OH. production. Our results show tha these agents to some extent exert their anti-inflammatory effects by interfering with the PMN-dependent production of oxygen intermediates, thus conferring protection from auto-oxidative tissue injury. This may account for their clinical efficacy in many PMN-mediated dermatological diseases.

Theoretical analysis of ozone generation by pulsed dielectric barrier discharge in oxygen

NASA Astrophysics Data System (ADS)

Wei, L. S.; Zhou, J. H.; Wang, Z. H.; Cen, K. F.

2007-08-01

The use of very short high-voltage pulses combined with a dielectric layer results in high-energy electrons that dissociate oxygen molecules into atoms, which are a prerequisite for the subsequent production of ozone by collisions with oxygen molecules and third particles. The production of ozone depends on both the electrical and the physical parameters. For ozone generation by pulsed dielectric barrier discharge in oxygen, a mathematical model, which describes the relation between ozone concentration and these parameters that are of importance in its design, is developed according to dimensional analysis theory. A formula considering the ozone destruction factor is derived for predicting the characteristics of the ozone generation, within the range of the corona inception voltage to the gap breakdown voltage. The trend showing the dependence of the concentration of ozone in oxygen on these parameters generally agrees with the experimental results, thus confirming the validity of the mathematical model.

An ISRU Propellant Production System to Fully Fuel a Mars Ascent Vehicle

NASA Technical Reports Server (NTRS)

Kleinhenz, Julie; Paz, Aaron

2017-01-01

ISRU of Mars resources was base lined in 2009 Design Reference Architecture (DRA) 5.0, but only for Oxygen production using atmospheric CO2The Methane (LCH4) needed for ascent propulsion of the Mars Ascent Vehicle (MAV) would need to be brought from Earth. HOWEVER: Extracting water from the Martian Regolith enables the production of both Oxygen and Methane from Mars resources Water resources could also be used for other applications including: Life support, radiation shielding, plant growth, etc. Water extraction was not base lined in DRA5.0 due to perceived difficulties and complexity in processing regolith. The NASA Evolvable Mars Campaign (EMC) requested studies to look at the quantitative benefits and trades of using Mars water ISRU Phase 1: Examined architecture scenarios for regolith water retrieval. Completed October 2015Phase 2: Deep dive of one architecture concept to look at end-to-end system size, mass, power of a LCH4LO2 ISRU production system.Evolvable Mars CampaignPre-deployed Mars ascent vehicle (MAV)4 crew membersPropellants: Oxygen MethaneGenerate a system model to roll up mass power of a full ISRU system and enable parametric trade studies. Leverage models from previous studies and technology development programs Anchor with mass power performance from existing hardware. Whenever possible used reference-able (published) numbers for traceability.Modular approach to allow subsystem trades and parametric studies. Propellant mass needs taken from most recently published MAV study:Polsgrove, T. et al. (2015), AIAA2015-4416MAV engines operate at mixture ratios (oxygen: methane) between 3:1 and 3.5:1, whereas the Sabatier reactor produces at a 4:1 ratio. Therefore:Methane production is the driving requirement-Excess Oxygen will be produced.

Potential and benefits of closed loop ECLS systems on the ISS.

PubMed

Raatschen, W; Preiss, H

2001-01-01

To close open loops for long manned missions in space is a big challenge for aeronautic engineers throughout the world. The paper's focus is on the oxygen reclamation from carbon dioxide within a space habitat. A brief description of the function principle of a fixed alkaline electrolyzer, a solid amine carbon dioxide concentrator and a Sabatier reactor is given. By combining these devices to an air revitalization system the technical and economical benefits are explained. Astrium's Air Revitalization System (ARES) as a potential future part of the International Space Station's Environmental Control and Life Support System would close the oxygen loop. The amount of oxygen, needed for an ISS crew of seven astronauts could be provided by ARES. The upload of almost 1500 kg of water annually for oxygen generation through the onboard electrolyzer would be reduced by more than 1000 kg, resulting in savings of more than 30M$ per year. Additionally, the payload capacity of supply flights would be increased by this amount of mass. Further possibilities are addressed to combine ECLS mass flows with those of the power, propulsion and attitude control systems. Such closed loop approaches will contribute to ease long time missions (e. g. Mars, Moon) from a cost and logistic point of view. The hardware realization of Astrium's space-sized operating ARES is shown and test results of continuous and intermittent closed chamber tests are presented. c2001 Astrium GmbH. Published by Elsevier Science Ltd.

DPPH and oxygen free radicals as pro-oxidant of biomolecules.

PubMed

Letelier, María Eugenia; Molina-Berríos, Alfredo; Cortés-Troncoso, Juan; Jara-Sandoval, José; Holst, Marianne; Palma, Karina; Montoya, Margarita; Miranda, Dante; González-Lira, Víctor

2008-03-01

Numerous investigations exist about the alterations that oxygen free radicals can provoke on biomolecules; these modifications can be prevented and/or reversed by different antioxidants agents. On the other hand, 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), a stable nitrogen synthetic radical, is used to evaluate the antioxidant capacity of medicinal herbal products; however, the structural changes that this radical provoke on the herbal active principles are not clear yet. In this work, we compared the redox reactivity of oxygen free radicals and DPPH radical on phospholipids and protein thiol groups present in rat liver microsomes. Cu2+/ascorbate was used as generator system of oxygen free radical and as antioxidant, an extract of Buddleja globosa's leaves. Cu2+/ascorbate provoked microsomal lipid peroxidation, microsomal thiols oxidation and oxygen consumption; all of these phenomena were inhibited by B. globosa extract. On the other hand, DPPH was bleached in different extension by the herbal extract and phosphatidyl choline; beside, DPPH decreased microsomal thiols content, but this phenomenon were not prevented by the herbal extract. Furthermore, DPPH did not induce oxygen consumption and neither modified the oxygen consumption induced by Cu2+/ascorbate. Distinct redox mechanisms may explain the differences between the reactivity of DPPH and oxygen free radicals on biomolecules, which is discussed.

Preoperative Cerebral Oxygen Extraction Fraction Imaging Generated from 7T MR Quantitative Susceptibility Mapping Predicts Development of Cerebral Hyperperfusion following Carotid Endarterectomy.

PubMed

Nomura, J-I; Uwano, I; Sasaki, M; Kudo, K; Yamashita, F; Ito, K; Fujiwara, S; Kobayashi, M; Ogasawara, K

2017-12-01

Preoperative hemodynamic impairment in the affected cerebral hemisphere is associated with the development of cerebral hyperperfusion following carotid endarterectomy. Cerebral oxygen extraction fraction images generated from 7T MR quantitative susceptibility mapping correlate with oxygen extraction fraction images on positron-emission tomography. The present study aimed to determine whether preoperative oxygen extraction fraction imaging generated from 7T MR quantitative susceptibility mapping could identify patients at risk for cerebral hyperperfusion following carotid endarterectomy. Seventy-seven patients with unilateral internal carotid artery stenosis (≥70%) underwent preoperative 3D T2*-weighted imaging using a multiple dipole-inversion algorithm with a 7T MR imager. Quantitative susceptibility mapping images were then obtained, and oxygen extraction fraction maps were generated. Quantitative brain perfusion single-photon emission CT was also performed before and immediately after carotid endarterectomy. ROIs were automatically placed in the bilateral middle cerebral artery territories in all images using a 3D stereotactic ROI template, and affected-to-contralateral ratios in the ROIs were calculated on quantitative susceptibility mapping-oxygen extraction fraction images. Ten patients (13%) showed post-carotid endarterectomy hyperperfusion (cerebral blood flow increases of ≥100% compared with preoperative values in the ROIs on brain perfusion SPECT). Multivariate analysis showed that a high quantitative susceptibility mapping-oxygen extraction fraction ratio was significantly associated with the development of post-carotid endarterectomy hyperperfusion (95% confidence interval, 33.5-249.7; P = .002). Sensitivity, specificity, and positive- and negative-predictive values of the quantitative susceptibility mapping-oxygen extraction fraction ratio for the prediction of the development of post-carotid endarterectomy hyperperfusion were 90%, 84%, 45%, and 98%, respectively. Preoperative oxygen extraction fraction imaging generated from 7T MR quantitative susceptibility mapping identifies patients at risk for cerebral hyperperfusion following carotid endarterectomy. © 2017 by American Journal of Neuroradiology.

Use of a Supraglottic Airway to Relieve Ventilation-Impeding Gastric Insufflation During Emergency Airway Management in an Infant.

PubMed

Dodd, Kenneth W; Strobel, Ashley M; Driver, Brian E; Reardon, Robert F

2016-10-01

Positive-pressure bag-valve-mask ventilation during emergency airway management often results in significant gastric insufflation, which may impede adequate ventilation and oxygenation. Current-generation supraglottic airways have beneficial features, such as channels for gastric decompression while ventilation is ongoing. A 5-week-old female infant required resuscitation for hypoxemic respiratory failure caused by rhinovirus with pneumonia. Bag-valve-mask ventilation led to gastric insufflation that compromised ventilation, thereby interfering with intubation because of precipitous oxygen desaturation during laryngoscopy. A current-generation supraglottic airway (LMA Supreme; Teleflex Inc, Morrisville, NC) was used to facilitate gastric decompression while ventilation and oxygenation was ongoing. After gastric decompression, ventilation was markedly improved and the pulse oxygen saturation improved to 100%. Intubation was successful on the next attempt, without oxygen desaturation. Current-generation supraglottic airways have 3 distinct advantages compared with first-generation supraglottic airways, which make them better devices for emergency airway management: gastric decompression ports, conduits for intubation, and higher oropharyngeal leak pressures. Copyright © 2016 American College of Emergency Physicians. Published by Elsevier Inc. All rights reserved.

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Generation of singlet oxygen in fullerene-containing media: 2. Fullerene-containing solutions

NASA Astrophysics Data System (ADS)

Bagrov, I. V.; Belousova, I. M.; Grenishin, A. S.; Danilov, O. B.; Ermakov, A. V.; Kiselev, V. M.; Kislyakov, I. M.; Murav'eva, T. D.; Sosnov, E. N.

2008-03-01

The generation of singlet oxygen in fullerene solutions is studied by luminescence methods upon excitation by pulsed, repetitively pulsed, and continuous radiation sources. The concentration of singlet oxygen in solutions is measured in stationary and pulsed irradiation regimes. The rate constants of quenching of O2(1Δg) by fullerenes C70 and C60 in the CCl4 solution are measured to be (7.2±0.1)×107 L mol-1 s-1 and less than 6×104 L mol-1 s-1, respectively. The temperature and photolytic variations in the generation properties of the fullerene solution exposed to intense continuous radiation are studied by the methods of optical and EPR spectroscopy. Pulsed irradiation resulted in the production of singlet oxygen in suspensions of fullerene-like structures, in particular, astralenes. A liquid pulsed singlet-oxygen generator based on the fullerene solution in CCl4 is developed and studied, in which the yield of O2 (1Δg) to the gas phase at concentrations up to 5×1016 cm-3 is obtained.

THERMOCHEMICAL CONVERSION OF FERMENTATION-DERIVED OXYGENATES TO FUELS

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

Ramasamy, Karthikeyan K.; Wang, Yong

2013-06-01

At present ethanol generated from renewable resources through fermentation process is the dominant biofuel. But ethanol suffers from undesirable fuel properties such as low energy density and high water solubility. The production capacity of fermentation derived oxygenates are projected to rise in near future beyond the current needs. The conversion of oxygenates to hydrocarbon compounds that are similar to gasoline, diesel and jet fuel is considered as one of the viable option. In this chapter the thermo catalytic conversion of oxygenates generated through fermentation to fuel range hydrocarbons will be discussed.

Chemical agents for the control of plaque and plaque microflora: an overview.

PubMed

Gaffar, A; Afflitto, J; Nabi, N

1997-10-01

This presentation provides an overview of the technologies available for the chemical control of plaque. It is generally accepted that the formation of dental plaque at the interfaces of tooth/gingiva is one of the major causes of gingival inflammation and dental caries. Several therapeutic approaches have been used to control dental plaque and supragingival infections. These include fluoride preparations such as stannous fluoride, oxygenating agents, anti-attachment agents, and cationic and non-cationic antibacterial agents. Among the fluoride preparations, stable stannous fluoride pastes and gels have been shown to reduce supragingival plaque, gingivitis, hypersensitivity and caries. The effect of the oxygenating agents on the supragingival plaque has been equivocal, but recent data indicate that a stable agent which provides sustained active oxygen release is effective in controlling plaque. A polymer, PVPA, which reduced attachment of bacteria to teeth was shown to significantly reduce plaque formation in humans. A new generation of antibacterials includes non-ionics such as triclosan, which in combination with a special polymer delivery system, has been shown to reduce plaque, gingivitis, supragingival calculus and dental caries in long-term studies conducted around the world. Unlike the first generation of agents, the triclosan/copolymer/sodium fluoride system is effective in long-term clinicals and does not cause staining of teeth, increase in calculus, or disturbance in the oral microbial ecology.

Atmospheric pressure cold plasma as an antifungal therapy

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

Sun Peng; Wu Haiyan; Sun Yi

2011-01-10

A microhollow cathode based, direct-current, atmospheric pressure, He/O{sub 2} (2%) cold plasma microjet was used to inactive antifungal resistants Candida albicans, Candida krusei, and Candida glabrata in air and in water. Effective inactivation (>90%) was achieved in 10 min in air and 1 min in water. Antifungal susceptibility tests showed drastic reduction of the minimum inhibitory concentration after plasma treatment. The inactivation was attributed to the reactive oxygen species generated in plasma or in water. Hydroxyl and singlet molecular oxygen radicals were detected in plasma-water system by electron spin resonance spectroscopy. This approach proposed a promising clinical dermatology therapy.

Molecular dynamics studies of pathways of water movement in cyanobacterial photosystem II

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

Gabdulkhakov, A. G., E-mail: azat@vega.protres.ru; Kljashtorny, V. G.; Dontsova, M. V.

2015-01-15

Photosystem II (PSII) catalyzes the light-induced generation of oxygen from water. The oxygen-evolving complex is buried deep in the protein on the lumenal side of PSII, and water molecules need to pass through protein subunits to reach the active site—the manganese cluster. Previous studies on the elucidation of water channels in PSII were based on an analysis of the cavities in the static PSII structure determined by X-ray diffraction. In the present study, we perform molecular dynamics simulations of the water movement in the transport system of PSII.

[Vitamin K3-induced activation of molecular oxygen in glioma cells].

PubMed

Krylova, N G; Kulagova, T A; Semenkova, G N; Cherenkevich, S N

2009-01-01

It has been shown by the method of fluorescent analysis that the rate of hydrogen peroxide generation in human U251 glioma cells under the effect of lipophilic (menadione) or hydrophilic (vikasol) analogues of vitamin K3 was different. Analyzing experimental data we can conclude that menadione underwent one- and two-electron reduction by intracellular reductases in glioma cells. Reduced forms of menadione interact with molecular oxygen leading to reactive oxygen species (ROS) generation. The theoretical model of ROS generation including two competitive processes of one- and two-electron reduction of menadione has been proposed. Rate constants of ROS generation mediated by one-electron reduction process have been estimated.

Bursch poses next to the Elektron oxygen generator in the SM during Expedition Four

NASA Image and Video Library

2002-04-26

ISS004-E-11791 (26 April 2002) --- Astronaut Daniel W. Bursch, Expedition Four flight engineer, works on the Elektron Oxygen Generator in the Zvezda Service Module on the International Space Station (ISS).

Walz poses next to the Elektron oxygen generator in the SM during Expedition Four

NASA Image and Video Library

2002-04-26

ISS004-E-11792 (26 April 2002) --- Astronaut Carl E. Walz, Expedition Four flight engineer, works on the Elektron Oxygen Generator in the Zvezda Service Module on the International Space Station (ISS).

Flame Resistant Fibrous Materials Development

NASA Technical Reports Server (NTRS)

Coskren, R. J.

1982-01-01

Since 1973, Albany International Research Co. has been engaged by NASA-JSC under Contract No. NAS9-13673 to conduct studies aimed at developing fibers and flexible structures made therefrom which would provide improved flame resistance over existing commercially available materials in oxygen enriched atmospheres. A portion of the crew bay area life support system and crew equipment for the space shuttle was initially designed to function at a 30% oxygen, 70% nitrogen atmosphere at 9 psia pressure. This oxygen concentration imposed certain fire safety and smoke generation requirements which could not be completely met by commonly accepted textiles. Potentially useful new polymers were investigated both for fire safety and mechanical properties. During the course of the work, three candidate fibers were studied and evaluated and the results of each of these efforts are summarized.

Food production and gas exchange system using blue-green alga (spirulina) for CELSS

NASA Technical Reports Server (NTRS)

Oguchi, Mitsuo; Otsubo, Koji; Nitta, Keiji; Hatayama, Shigeki

1987-01-01

In order to reduce the cultivation area required for the growth of higher plants in space adoption of algae, which have a higher photosynthetic ability, seems very suitable for obtaining oxygen and food as a useful source of high quality protein. The preliminary cultivation experiment for determining optimum cultivation conditions and for obtaining the critical design parameters of the cultivator itself was conducted. Spirulina was cultivated in the 6 liter medium containing a sodium hydrogen carbonate solution and a cultivation temperature controlled using a thermostat. Generated oxygen gas was separated using a polypropyrene porous hollow fiber membrane module. Through this experiment, oxygen gas (at a concentration of more than 46 percent) at a rate of 100 to approx. 150 ml per minute could be obtained.

Generation and Role of Reactive Oxygen and Nitrogen Species Induced by Plasma, Lasers, Chemical Agents, and Other Systems in Dentistry

PubMed Central

Jha, Nayansi; Ryu, Jae Jun

2017-01-01

The generation of reactive oxygen and nitrogen species (RONS) has been found to occur during inflammatory procedures, during cell ischemia, and in various crucial developmental processes such as cell differentiation and along cell signaling pathways. The most common sources of intracellular RONS are the mitochondrial electron transport system, NADH oxidase, and cytochrome P450. In this review, we analyzed the extracellular and intracellular sources of reactive species, their cell signaling pathways, the mechanisms of action, and their positive and negative effects in the dental field. In dentistry, ROS can be found—in lasers, photosensitizers, bleaching agents, cold plasma, and even resin cements, all of which contribute to the generation and prevalence of ROS. Nonthermal plasma has been used as a source of ROS for biomedical applications and has the potential for use with dental stem cells as well. There are different types of dental stem cells, but their therapeutic use remains largely untapped, with the focus currently on only periodontal ligament stem cells. More research is necessary in this area, including studies about ROS mechanisms with dental cells, along with the utilization of reactive species in redox medicine. Such studies will help to provide successful treatment modalities for various diseases. PMID:29204250

Photodynamic therapy: computer modeling of diffusion and reaction phenomena

NASA Astrophysics Data System (ADS)

Hampton, James A.; Mahama, Patricia A.; Fournier, Ronald L.; Henning, Jeffery P.

1996-04-01

We have developed a transient, one-dimensional mathematical model for the reaction and diffusion phenomena that occurs during photodynamic therapy (PDT). This model is referred to as the PDTmodem program. The model is solved by the Crank-Nicholson finite difference technique and can be used to predict the fates of important molecular species within the intercapillary tissue undergoing PDT. The following factors govern molecular oxygen consumption and singlet oxygen generation within a tumor: (1) photosensitizer concentration; (2) fluence rate; and (3) intercapillary spacing. In an effort to maximize direct tumor cell killing, the model allows educated decisions to be made to insure the uniform generation and exposure of singlet oxygen to tumor cells across the intercapillary space. Based on predictions made by the model, we have determined that the singlet oxygen concentration profile within the intercapillary space is controlled by the product of the drug concentration, and light fluence rate. The model predicts that at high levels of this product, within seconds singlet oxygen generation is limited to a small core of cells immediately surrounding the capillary. The remainder of the tumor tissue in the intercapillary space is anoxic and protected from the generation and toxic effects of singlet oxygen. However, at lower values of this product, the PDT-induced anoxic regions are not observed. An important finding is that an optimal value of this product can be defined that maintains the singlet oxygen concentration throughout the intercapillary space at a near constant level. Direct tumor cell killing is therefore postulated to depend on the singlet oxygen exposure, defined as the product of the uniform singlet oxygen concentration and the time of exposure, and not on the total light dose.

Butanol / Gasoline Mercury CRADA Report

DTIC Science & Technology

2015-03-01

oxygenated fuel, which increases in-cylinder temperatures and thus generates higher NOx emissions. 3.2 Modifications to the SPC-TB 3.2.1 Data Collection...emissions.  Emissions of oxides of Nitrogen (NOx) are higher with oxygenated fuel. NOx generation is a function of the time spent at high temperature ...pressure in the combustion chamber. The engines run leaner and hotter with oxygenated fuel, which increases in-cylinder temperatures and thus

Oxygen monitor for semi-closed rebreathers: design and use for estimating metabolic oxygen consumption

NASA Astrophysics Data System (ADS)

Clarke, John R.; Southerland, David

1999-07-01

Semi-closed circuit underwater breathing apparatus (UBA) provide a constant flow of mixed gas containing oxygen and nitrogen or helium to a diver. However, as a diver's work rate and metabolic oxygen consumption varies, the oxygen percentages within the UBA can change dramatically. Hence, even a resting diver can become hypoxic and become at risk for oxygen induced seizures. Conversely, a hard working diver can become hypoxic and lose consciousness. Unfortunately, current semi-closed UBA do not contain oxygen monitors. We describe a simple oxygen monitoring system designed and prototyped at the Navy Experimental Diving Unit. The main monitor components include a PIC microcontroller, analog-to-digital converter, bicolor LED, and oxygen sensor. The LED, affixed to the diver's mask is steady green if the oxygen partial pressure is within pre- defined acceptable limits. A more advanced monitor with a depth senor and additional computational circuitry could be used to estimate metabolic oxygen consumption. The computational algorithm uses the oxygen partial pressure and the diver's depth to compute O2 using the steady state solution of the differential equation describing oxygen concentrations within the UBA. Consequently, dive transients induce errors in the O2 estimation. To evalute these errors, we used a computer simulation of semi-closed circuit UBA dives to generate transient rich data as input to the estimation algorithm. A step change in simulated O2 elicits a monoexponential change in the estimated O2 with a time constant of 5 to 10 minutes. Methods for predicting error and providing a probable error indication to the diver are presented.

Full Scale Alternative Catalyst Testing for Bosch Reactor Optimization

NASA Technical Reports Server (NTRS)

Barton, Katherine; Abney, Morgan B.

2011-01-01

Current air revitalization technology onboard the International Space Station (ISS) cannot provide complete closure of the oxygen and hydrogen loops. This makes re-supply necessary, which is possible for missions in low Earth orbit (LEO) like the ISS, but unviable for long term space missions outside LEO. In comparison, Bosch technology reduces carbon dioxide with hydrogen, traditionally over a steel wool catalyst, to create water and solid carbon. The Bosch product water can then be fed to the oxygen generation assembly to produce oxygen for crew members and hydrogen necessary to reduce more carbon dioxide. Bosch technology can achieve complete oxygen loop closure, but has many undesirable factors that result in a high energy, mass, and volume system. Finding a different catalyst with an equal reaction rate at lower temperatures with less catalyst mass and longer lifespan would make a Bosch flight system more feasible. Developmental testing of alternative catalysts for the Bosch has been performed using the Horizontal Bosch Test Stand. Nickel foam, nickel shavings, and cobalt shavings were tested at 500 C and compared to the original catalyst, steel wool. This paper presents data and analysis on the performance of each catalyst tested at comparable temperatures and recycle flow rates.

A comparison of the phototoxic potency of six types of TiO2 nanoparticles

EPA Science Inventory

Nanoparticles,such as nano-TiO2, are often photo active and can become photo toxic by the generation of reactive oxygen species (ROS) and free-radical oxidative damage to surrounding tissues. Because the retina is the only part of the central nervous system directly exposed to li...

Transformation of soil microbial community structure in response to anaerobic soil disinfestation for soil-borne disease control in strawberry

USDA-ARS?s Scientific Manuscript database

Anaerobic soil disinfestation (ASD) has been used to control soil-borne pathogens and nematodes in various plant production systems including strawberries. Disease control is commonly attributed to the depletion of oxygen and the generation of toxic compounds, including organic acids and volatiles....

Mitigating hypoxic stress on pancreatic islets via in situ oxygen generating biomaterial.

PubMed

Coronel, Maria M; Geusz, Ryan; Stabler, Cherie L

2017-06-01

A major obstacle in the survival and efficacy of tissue engineered transplants is inadequate oxygenation, whereby unsupportive oxygen tensions result in significant cellular dysfunction and death within the implant. In a previous report, we developed an innovative oxygen generating biomaterial, termed OxySite, to provide supportive in situ oxygenation to cells and prevent hypoxia-induced damage. Herein, we explored the capacity of this biomaterial to mitigate hypoxic stress in both rat and nonhuman primate pancreatic islets by decreasing cell death, supporting metabolic activity, sustaining aerobic metabolism, preserving glucose responsiveness, and decreasing the generation of inflammatory cytokines. Further, the impact of supplemental oxygenation on in vivo cell function was explored by the transplantation of islets previously co-cultured with OxySite into a diabetic rat model. Transplant outcomes revealed significant improvement in graft efficacy for OxySite-treated islets, when transplanted within an extrahepatic site. These results demonstrate the potency of the OxySite material to mitigate activation of detrimental hypoxia-induced pathways in islets during culture and highlights the importance of in situ oxygenation on resulting islet transplant outcomes. Copyright © 2017 Elsevier Ltd. All rights reserved.

A smart upconversion-based light-triggered polymer for synergetic chemo-photodynamic therapy and dual-modal MR/UCL imaging.

PubMed

Du, Bin; Han, Shuping; Zhao, Feifei; Lim, Kok Hwa; Xi, Hongwei; Su, Xiangjie; Yao, Hanchun; Zhou, Jie

2016-10-01

We have developed a novel nanocomposite to achieve effective therapy and live surveillance of tumor tissue. In this study, fullerene (C 60 ) with iron oxide (Fe 3 O 4 ) nanoparticles and upconversion nanophosphors (UCNPs) was loaded into N-succinyl-N'-4-(2-nitrobenzyloxy)-succinyl-chitosan micelles (SNSC) with good biocompatibility. In addition, hydrophobic anticancer drug docetaxel (DTX) was also loaded into the nanocomposites. The experiments conducted in vitro and in vivo demonstrated that C 60 /Fe 3 O 4 -UCNPs@DTX@SNSC can act synergistically to kill tumor cells by releasing chemotherapy drugs at specific target site as well as generating reactive oxygen using 980nm. In addition, it can also be used for non-invasive deep magnetic resonance and upconversion fluorescence dual-mode imaging. The results indicated that this system provided an efficient method to surmount the drawback of UV or visible light-responsive polymeric systems for controlled drug release and generated reactive oxygen in deep tissues and ultimately realized the integration of dual-modal imaging and treatment. Copyright © 2016 Elsevier Inc. All rights reserved.

Graphene oxide functionalized with methylene blue and its performance in singlet oxygen generation

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

Wojtoniszak, M., E-mail: mwojtoniszak@zut.edu.pl; Rogińska, D.; Machaliński, B.

2013-07-15

Graphical abstract: - Highlights: • Adsorption of methylene blue (MB) on graphene oxide (GO). • Characterization of graphene oxide–methylene blue nanocomposite (MB–GO). • Examination of MB–GO efficiency in singlet oxygen generation (SOG). • MB–GO performs higher SOG efficiency than pristine MB. - Abstract: Due to unique electronic, mechanical, optical and structural properties, graphene has shown promising applications in many fields, including biomedicine. One of them is noninvasive anticancer therapy – photodynamic therapy (PDT), where singlet oxygen (SO), generated under the irradiation of light with appropriate wavelengths, kills cancer cells. In this study, authors report graphene oxide (GO) noncovalent functionalization withmore » methylene blue (MB). MB molecules underwent adsorption on the surface of GO. Detailed characterization of the obtained material was carried out with UV–vis spectroscopy, Raman spectroscopy, FT-IR spectroscopy, and confocal laser scanning microscopy. Furthermore, its performance in singlet oxygen generation (SOG) under irradiation of laser with excitation wavelengths of 785 nm was investigated. Interestingly, GO functionalized with MB (MB–GO) showed enhanced efficiency in singlet oxygen generation compared to pristine MB. The efficiency in SOG was detected by photobleaching of 9,10-anthracenediyl-bis(methylene)dimalonic acid (ABMDMA). These results indicate the material is promising in PDT anticancer therapy and further in vitro and in vivo studies are required.« less

Investigating pyrolysis/incineration as a method of resource recovery from solid waste

NASA Technical Reports Server (NTRS)

Robertson, Bobby J.; Lemay, Christopher S.

1993-01-01

Pyrolysis/incineration (P/I) is a physicochemical method for the generation of recoverable resources from solid waste materials such as inedible plant biomass (IPB), paper, plastics, cardboard, etc. P/I permits the collection of numerous gases with a minimal amount of solid residue. Pyrolysis, also known as starved air incineration, is usually conducted at relatively high temperatures (greater than 500 deg C) in the absence of oxygen. Incineration is conducted at lower temperatures in the presence of oxygen. The primary purpose of this study was to design, construct, and test a model P/I. The system design includes safety requirements for temperature and pressure. The objectives of this study were: (1) to design and construct a P/I system for incorporation with the Hybrid Regenerative Water Recovery System; (2) to initiate testing of the P/I system; (3) to collect and analyze P/I system data; (4) to consider test variables; and (5) to determine the feasibility of P/I as an effective method of resource recovery. A P/I system for the recovery of reuseable resources from solid waste materials was designed, constructed, and tested. Since a large amount of inedible plant biomass (IPB) will be generated in a space-based habitat on the lunar surface and Mars, IPB was the primary waste material tested in the system. Analysis of the effluent gases was performed to determine which gases could be used in a life support system.

Mechanism of singlet oxygen deactivation in an electric discharge oxygen – iodine laser

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

Azyazov, V N; Mikheyev, P A; Torbin, A P

2014-12-31

We have determined the influence of the reaction of molecular singlet oxygen with a vibrationally excited ozone molecule O{sub 2}(a {sup 1}Δ) + O{sub 3}(ν) → 2O{sub 2} + O on the removal rate of O{sub 2}(a {sup 1}Δ) in an electric-discharge-driven oxygen – iodine laser. This reaction has been shown to be a major channel of O{sub 2}(a {sup 1}Δ) loss at the output of an electric-discharge singlet oxygen generator. In addition, it can also contribute significantly to the loss of O{sub 2}(a {sup 1}Δ) in the discharge region of the generator. (lasers)

The influence of excitation radiation parameters on photosensitized generation of singlet oxygen in water

NASA Astrophysics Data System (ADS)

Il'ina, A. D.; Glazov, A. L.; Semenova, I. V.; Vasyutinskii, O. S.

2016-06-01

Photosensitized generation of singlet oxygen with the aid of Radahlorin® photosensitizer has been investigated. The dependences of the intensity of singlet oxygen phosphorescence and photosensitizer fluorescence on the excitation radiation wavelength in the range of 350-440 nm and on the irradiation dose have been obtained. The dependence of the ratio of the sensitizer fluorescence intensity at about 670 nm to the singlet oxygen phosphorescence intensity at a wavelength of 1270 nm on the excitation radiation wavelength is found to be nonmonotonic and have a minimum near the center of the absorption band on its red wing. The results obtained can be used to monitor the singlet oxygen concentration in solutions.

Microdistribution of oxygen in silicon and its effects on electronic properties

NASA Technical Reports Server (NTRS)

Gatos, H. C.; Mao, B. Y.; Nauka, K.; Lagowski, J.

1982-01-01

The effects of interstitial oxygen on the electrical characteristics of Czochralski-grown silicon crystals were investigated for the first time on a microscale. It was found that the generation of thermal donors is not a direct function of the oxygen concentration. It was further found that the minority carrier life-time decreases with increasing oxygen concentration, on a microscale in as-grown crystals. It was thus shown, again for the first time, that oxygen in as grown crystals is not electronically inert as generally believed. Preannealing at 1200 C commonly employed in device fabrication, was found to suppress the donor generation at 450 C and to decrease the deep level concentrations.

Regulation of a polyamine transporter by the conserved 3′ UTR-derived sRNA SorX confers resistance to singlet oxygen and organic hydroperoxides in Rhodobacter sphaeroides

PubMed Central

Peng, Tao; Berghoff, Bork A.; Oh, Jeong-Il; Weber, Lennart; Schirmer, Jasmin; Schwarz, Johannes; Glaeser, Jens; Klug, Gabriele

2016-01-01

ABSTRACT Singlet oxygen is generated by bacteriochlorophylls when light and oxygen are simultaneously present in Rhodobacter sphaeroides. Singlet oxygen triggers a specific response that is partly regulated by the alternative sigma factor RpoHI/HII. The sRNA RSs2461 has previously been identified as an RpoHI/HII-dependent sRNA and is derived from the 3′ UTR of the mRNA for an OmpR-type transcriptional regulator. Similar to the RpoHI/HII-dependent CcsR and SorY sRNAs, RSs2461 affects the resistance of R. sphaeroides against singlet oxygen and was therefore renamed here SorX. Furthermore, SorX has a strong impact on resistance against organic hydroperoxides that usually occur as secondary damages downstream of singlet oxygen. The 75-nt SorX 3′ fragment, which is generated by RNase E cleavage and highly conserved among related species, represents the functional entity. A target search identified potA mRNA, which encodes a subunit of a polyamine transporter, as a direct SorX target and stress resistance via SorX could be linked to potA. The PotABCD transporter is an uptake system for spermidine in E. coli. While spermidine is generally described as beneficial during oxidative stress, we observed significantly increased sensitivity of R. sphaeroides to organic hydroperoxides in the presence of spermidine. We therefore propose that the diminished import of spermidine, due to down-regulation of potA by SorX, counteracts oxidative stress. Together with results from other studies this underlines the importance of regulated transport to bacterial stress defense. PMID:27420112

Regulation of a polyamine transporter by the conserved 3' UTR-derived sRNA SorX confers resistance to singlet oxygen and organic hydroperoxides in Rhodobacter sphaeroides.

PubMed

Peng, Tao; Berghoff, Bork A; Oh, Jeong-Il; Weber, Lennart; Schirmer, Jasmin; Schwarz, Johannes; Glaeser, Jens; Klug, Gabriele

2016-10-02

Singlet oxygen is generated by bacteriochlorophylls when light and oxygen are simultaneously present in Rhodobacter sphaeroides. Singlet oxygen triggers a specific response that is partly regulated by the alternative sigma factor RpoHI/HII. The sRNA RSs2461 has previously been identified as an RpoHI/HII-dependent sRNA and is derived from the 3' UTR of the mRNA for an OmpR-type transcriptional regulator. Similar to the RpoHI/HII-dependent CcsR and SorY sRNAs, RSs2461 affects the resistance of R. sphaeroides against singlet oxygen and was therefore renamed here SorX. Furthermore, SorX has a strong impact on resistance against organic hydroperoxides that usually occur as secondary damages downstream of singlet oxygen. The 75-nt SorX 3' fragment, which is generated by RNase E cleavage and highly conserved among related species, represents the functional entity. A target search identified potA mRNA, which encodes a subunit of a polyamine transporter, as a direct SorX target and stress resistance via SorX could be linked to potA. The PotABCD transporter is an uptake system for spermidine in E. coli. While spermidine is generally described as beneficial during oxidative stress, we observed significantly increased sensitivity of R. sphaeroides to organic hydroperoxides in the presence of spermidine. We therefore propose that the diminished import of spermidine, due to down-regulation of potA by SorX, counteracts oxidative stress. Together with results from other studies this underlines the importance of regulated transport to bacterial stress defense.

Correlation of fetal oxygen saturation to fetal heart rate patterns. Evaluation of fetal pulse oximetry with two different oxisensors.

PubMed

Luttkus, A K; Friedmann, W; Homm-Luttkus, C; Dudenhausen, J W

1998-03-01

The purpose of this study was the correlation of fetal oxygen saturation values to various fetal heart rate patterns, as well as to oxygen saturation values obtained by fetal blood analysis. These objectives need to be evaluated from the perspective that two generations of fetal oxisensors have been used. Two different oxisensor systems (FS10: 660+890 nm and FS14: 735+890 nm) and a blinded pulse oximeter (type N400, Nellcor Puritan Bennett) were utilized to monitor 112 fetuses. All data, including oxygen saturation, fetal heart rate patterns, signal and contact quality were stored on a personal computer and evaluated after delivery. The following median fetal oxygen saturation values were obtained: during reassuring fetal heart rate sequences 54% with the oxisensor FS10 and 48% with the newer FS14 oxisensor, during intervals of variable decelerations 43% with the FS10 oxisensor and 40% with the FS14 oxisensor. These differences between values obtained during normal and abnormal fetal heart rate patterns are significant. Due to non-reassuring fetal heart rate patterns 81 fetal blood analyses were performed. The values of pulse oximetry were 9% higher (6% for the FS14) than those of spectrophotometry. Correlation of both methods was r=0.66 (0.74 for the FS14). In combination with fetal heart rate monitoring, fetal pulse oximetry promises a better differentiation between low and high risk heart rate patterns. Oxygen saturation values from intermittent fetal blood sampling reassure the clinician concerning the accuracy of this new method of intrapartum fetal surveillance and underline the increased quality of the new generation of oxisensor using light of a wavelength of 735 and 890 nm.

Potential Danger of Pre-Pump Clamping on Negative Pressure-Associated Gaseous Microemboli Generation During Extracorporeal Life Support--An In Vitro Study.

PubMed

Wang, Shigang; Chin, Brian J; Gentile, Frank; Kunselman, Allen R; Palanzo, David; Ündar, Akif

2016-01-01

The objectives of this study were to investigate the relationship between revolution speed of a conventional centrifugal pump and negative pressure at the inlet of the pump by clamping the tubing upstream of the pump, and to verify whether negative pressure leads to gaseous microemboli (GME) production in a simulated adult extracorporeal life support (ECLS) system. The experimental circuit, including a Maquet Rotaflow centrifugal pump and a Medos Hilite 7000 LT polymethyl-pentene membrane oxygenator, was primed with packed red blood cells (hematocrit 35%). Negative pressure was created in the circuit by clamping the tubing upstream of the pump for 10 s, and then releasing the clamp. An emboli detection and classification quantifier was used to record GME volume and count at pre-oxygenator and post-oxygenator sites, and pressure and flow rate data were collected using a custom-based data acquisition system. All trials were conducted at 36°C at revolution speeds of 2000-4000 rpm (500 rpm increment). The flow rates were 1092.5-4708.4 mL/min at the revolution speeds of 2000-4000 rpm. Higher revolution speed generated higher negative pressure at the pre-pump site when clamping the tubing upstream of the pump (-108.3 ± 0.1 to -462.0 ± 0.5 mm Hg at 2000-4000 rpm). Moreover, higher negative pressure was associated with a larger number and volume of GME at pre-oxygenator site after de-clamp (GME count 10,573 ± 271 at pre-oxygenator site at 4000 rpm). The results showed that there was a potential danger of delivering GME to the patient when clamping pre-pump tubing during ECLS using a centrifugal pump. Our results warrant further clinical studies to investigate this phenomenon. Copyright © 2015 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Development of a static feed water electrolysis system

NASA Technical Reports Server (NTRS)

Schubert, F. H.; Lantz, J. B.; Hallick, T. M.

1982-01-01

A one person level oxygen generation subsystem was developed and production of the one person oxygen metabolic requirements, 0.82 kg, per day was demonstrated without the need for condenser/separators or electrolyte pumps. During 650 hours of shakedown, design verification, and endurance testing, cell voltages averaged 1.62 V at 206 mA/sq cm and at average operating temperature as low as 326 K, virtually corresponding to the state of the art performance previously established for single cells. This high efficiency and low waste heat generation prevented maintenance of the 339 K design temperature without supplemental heating. Improved water electrolysis cell frames were designed, new injection molds were fabricated, and a series of frames was molded. A modified three fluid pressure controller was developed and a static feed water electrolysis that requires no electrolyte in the static feed compartment was developed and successfully evaluated.

Photoinduced DNA damage and cytotoxicity by a triphenylamine-modified platinum-diimine complex.

PubMed

Zhang, Zhigang; Dai, Ruihui; Ma, Jiajia; Wang, Shuying; Wei, Xuehong; Wang, Hongfei

2015-02-01

Many planar photosensitizers tend to self-aggregate via van der Waals interactions between π-conjugated systems. The self-aggregation of the photosensitizer may reduce the efficiency of the photosensitizer to generate singlet oxygen, thereby diminishing its photodynamic activity. Efforts have been made to improve the photodynamic activity of bis-(o-diiminobenzosemiquinonato)platinum(II) which has planar geometry by the introduction of the sterically hindered triphenylamine moiety into the ligand. Herein we report the photoinduced DNA damage and cytotoxicity by a triphenylamine-modified platinum-diimine complex in red light studied by fluorescence spectra, agarose gel assay and cell viability assay. The results suggest that the triphenylamine-modified platinum-diimine complex has better capability to generate singlet oxygen than bis-(o-diiminobenzosemiquinonato)platinum(II), and it can induce DNA damage in red light, causing high photocytotoxicity in HepG-2 cells in vitro. Copyright © 2014 Elsevier Inc. All rights reserved.

Technology advancement of the static feed water electrolysis process

NASA Technical Reports Server (NTRS)

Schubert, F. H.; Wynveen, R. A.

1977-01-01

A program to advance the technology of oxygen- and hydrogen-generating subsystems based on water electrolysis was studied. Major emphasis was placed on static feed water electrolysis, a concept characterized by low power consumption and high intrinsic reliability. The static feed based oxygen generation subsystem consists basically of three subassemblies: (1) a combined water electrolysis and product gas dehumidifier module; (2) a product gas pressure controller and; (3) a cyclically filled water feed tank. Development activities were completed at the subsystem as well as at the component level. An extensive test program including single cell, subsystem and integrated system testing was completed with the required test support accessories designed, fabricated, and assembled. Mini-product assurance activities were included throughout all phases of program activities. An extensive number of supporting technology studies were conducted to advance the technology base of the static feed water electrolysis process and to resolve problems.

KSC-97pc673

NASA Image and Video Library

1997-04-19

KENNEDY SPACE CENTER, FLA. -- McDonnell Douglas-SPACEHAB technicians oversee the move of a Russian-made oxygen generator to a SPACEHAB Double Module, at rear, in the SPACEHAB Payload Processing Facility. With faces visible in center foreground, from left, are Mark Halavin and Marc Tuttle; Mike Vawter is at far right. The oxygen generator, manufactured in Russia by RSC Energia, will be carried aboard the Space Shuttle Atlantis on Mission STS-84 for the Shuttle’s scheduled docking with the Russian Space Station Mir next month. The nearly 300-pound generator will replace one of two Mir units that have been malfunctioning recently. The generator functions by electrolysis, which separates water into its oxygen and hydrogen components. The hydrogen is vented and the oxygen is used for breathing by the Mir crew. The generator is 4.2 feet in length and 1.4 feet in diameter. STS-84, which is planned to include a Mir crew exchange of astronaut C. Michael Foale for Jerry M. Linenger, is targeted for a May 15 liftoff. It will be the sixth Shuttle-Mir docking

Endogenous Generation of Singlet Oxygen and Ozone in Human and Animal Tissues: Mechanisms, Biological Significance, and Influence of Dietary Components.

PubMed

Onyango, Arnold N

2016-01-01

Recent studies have shown that exposing antibodies or amino acids to singlet oxygen results in the formation of ozone (or an ozone-like oxidant) and hydrogen peroxide and that human neutrophils produce both singlet oxygen and ozone during bacterial killing. There is also mounting evidence that endogenous singlet oxygen production may be a common occurrence in cells through various mechanisms. Thus, the ozone-producing combination of singlet oxygen and amino acids might be a common cellular occurrence. This paper reviews the potential pathways of formation of singlet oxygen and ozone in vivo and also proposes some new pathways for singlet oxygen formation. Physiological consequences of the endogenous formation of these oxidants in human tissues are discussed, as well as examples of how dietary factors may promote or inhibit their generation and activity.

Endogenous Generation of Singlet Oxygen and Ozone in Human and Animal Tissues: Mechanisms, Biological Significance, and Influence of Dietary Components

PubMed Central

2016-01-01

Recent studies have shown that exposing antibodies or amino acids to singlet oxygen results in the formation of ozone (or an ozone-like oxidant) and hydrogen peroxide and that human neutrophils produce both singlet oxygen and ozone during bacterial killing. There is also mounting evidence that endogenous singlet oxygen production may be a common occurrence in cells through various mechanisms. Thus, the ozone-producing combination of singlet oxygen and amino acids might be a common cellular occurrence. This paper reviews the potential pathways of formation of singlet oxygen and ozone in vivo and also proposes some new pathways for singlet oxygen formation. Physiological consequences of the endogenous formation of these oxidants in human tissues are discussed, as well as examples of how dietary factors may promote or inhibit their generation and activity. PMID:27042259

Kinetics of oxygen species in an electrically driven singlet oxygen generator

NASA Astrophysics Data System (ADS)

Azyazov, V. N.; Torbin, A. P.; Pershin, A. A.; Mikheyev, P. A.; Heaven, M. C.

2015-12-01

The kinetics of oxygen species in the gaseous medium of a discharge singlet oxygen generator has been revisited. Vibrationally excited ozone O3(υ) formed in O + O2 recombination is thought to be a significant agent in the deactivation of singlet oxygen O2(a1Δ), oxygen atom removal and ozone formation. It is shown that the process O3(υ ⩾ 2) + O2(a1Δ) → 2O2 + O is the main O2(a1Δ) deactivation channel in the post-discharge zone. If no measures are taken to decrease the oxygen atom concentration, the contribution of this process to the overall O2(a1Δ) removal is significant, even in the discharge zone. A simplified model for the kinetics of vibrationally excited ozone is proposed. Calculations based on this model yield results that are in good agreement with the experimental data.

The response of aircraft oxygen generators exposed to elevated temperatures

DOT National Transportation Integrated Search

2003-04-01

The purpose of this testing was to determine the temperatures that would cause self-activation of sodium chlorate oxygen generators. The data will be used to establish the degree of thermal protection that would be required to prevent the activation ...

Onufrienko makes repairs to the Elektron oxygen generator in the SM during Expedition Four

NASA Image and Video Library

2002-04-26

ISS004-E-11793 (26 April 2002) --- Cosmonaut Yury I. Onufrienko, Expedition Four mission commander, performs maintenance on the Elektron Oxygen Generator in the Zvezda Service Module on the International Space Station (ISS). Onufrienko represents Rosaviakosmos.

Oxygen-Free Biochemistry: The Putative CHN Foundation for Exotic Life in a Hydrocarbon World?

PubMed

Lv, Kong-Peng; Norman, Lucy; Li, Yi-Liang

2017-11-01

Since Earth's biochemistry is carbon-based and water-borne, the main strategies for searching for life elsewhere are "follow the carbon" and "follow the water." Recently, however, there is a growing focus on the prospect that putative exotic life on other planets could rely on unearthly biochemistries. Here, we hypothesize a novel oxygen-free organic chemistry for supporting potential exotic biosystems, which is named CHN biochemistry. This oxygen-free CHN biochemistry starts from simple oxygen-free species (including hydrocarbons, hydrogen cyanide, and nitriles) and produces a range of functional macromolecules that may function in similar ways to terran macromolecules, such as sugars (cyanosugars), acids (cyanoacids), amino acids (amino cyanoacids), and nucleobases (cyanonucleobases). These CHN macromolecules could further interact with each other to generate higher "cyanoester" and "cyanoprotein" systems. In addition, theoretical calculations indicate that the energy changes of some reactions are consistent with their counterparts in Earth's biochemistry. The CHN biochemistry-based life would be applicable in habitats with a low bioavailability of oxygen, such as the alkane lakes of Titan and non-aquatic liquids on extrasolar bodies. Key Words: Oxygen-free biochemistry-Titan-Hydrocarbons-Hydrogen cyanide-Nitriles. Astrobiology 17, 1173-1181.

O2(a1Δ) Quenching In The O/O2/O3 System

NASA Astrophysics Data System (ADS)

Azyazov, V. N.; Mikheyev, P. A.; Postell, D.; Heaven, M. C.

2010-10-01

The development of discharge singlet oxygen generators (DSOG's) that can operate at high pressures is required for the power scaling of the discharge oxygen iodine laser. In order to achieve efficient high-pressure DSOG operation it is important to understand the mechanisms by which singlet oxygen (O2(a1Δ)) is quenched in these devices. It has been proposed that three-body deactivation processes of the type O2(a1Δ)+O+M→2O2+M provide significant energy loss channels. To further explore these reactions the physical and reactive quenching of O2(a1Δ) in O(3P)/O2/O3/CO2/He/Ar mixtures has been investigated. Oxygen atoms and singlet oxygen molecules were produced by the 248 nm laser photolysis of ozone. The kinetics of O2(a1Δ) quenching were followed by observing the 1268 nm fluorescence of the O2a1Δ-X3∑ transition. Fast quenching of O2(a1Δ) in the presence of oxygen atoms and molecules was observed. The mechanism of the process has been examined using kinetic models, which indicate that quenching by vibrationally excited ozone is the dominant reaction.

Automated Reflectance Measurement System Designed and Fabricated to Determine the Limits of Atomic Oxygen Treatment of Art Through Contrast Optimization

NASA Technical Reports Server (NTRS)

Sechkar, Edward A.; Stueber, Thomas J.; Rutledge, Sharon K.

2000-01-01

Atomic oxygen generated in ground-based research facilities has been used to not only test erosion of candidate spacecraft materials but as a noncontact technique for removing organic deposits from the surfaces of artwork. NASA has patented the use of atomic oxygen to remove carbon-based soot contamination from fire-damaged artwork. The process of cleaning soot-damaged paintings with atomic oxygen requires exposures for variable lengths of time, dependent on the condition of a painting. Care must be exercised while cleaning to prevent the removal of pigment. The cleaning process must be stopped as soon as visual inspection or surface reflectance measurements indicate that cleaning is complete. Both techniques rely on optical comparisons of known bright locations against known dark locations on the artwork being cleaned. Difficulties arise with these techniques when either a known bright or dark location cannot be determined readily. Furthermore, dark locations will lighten with excessive exposure to atomic oxygen. Therefore, an automated test instrument to quantitatively characterize cleaning progression was designed and developed at the NASA Glenn Research Center at Lewis Field to determine when atomic oxygen cleaning is complete.

Degradation mechanisms of 4-chlorophenol in a novel gas-liquid hybrid discharge reactor by pulsed high voltage system with oxygen or nitrogen bubbling.

PubMed

Zhang, Yi; Zhou, Minghua; Hao, Xiaolong; Lei, Lecheng

2007-03-01

The effect of gas bubbling on the removal efficiency of 4-chlorophenol (4-CP) in aqueous solution has been investigated using a novel pulsed high voltage gas-liquid hybrid discharge reactor, which generates gas-phase discharge above the water surface simultaneously with the spark discharge directly in the liquid. The time for 100% of 4-CP degradation in the case of oxygen bubbling (7 min) was much shorter than that in the case of nitrogen bubbling (25 min) as plenty of hydrogen peroxide and ozone formed in oxygen atmosphere enhanced the removal efficiency of 4-CP. Except for the main similar intermediates (4-chlorocatechol, hydroquinone and 1,4-benzoquinone) produced in the both cases of oxygen and nitrogen bubbling, special intermediates (5-chloro-3-nitropyrocatechol, 4-chloro-2-nitrophenol, nitrate and nitrite ions) were produced in nitrogen atmosphere. The reaction pathway of 4-CP in the case of oxygen bubbling was oxygen/ozone attack on the radical hydroxylated derivatives of 4-CP. However, in the case of nitrogen bubbling, hydroxylation was the main reaction pathway with effect of N atom on degradation of 4-CP.

Gaseous Microemboli and the Influence of Microporous Membrane Oxygenators

PubMed Central

Weitkemper, Heinz-H.; Oppermann, Bernd; Spilker, Andreas; Knobl, Hermann-J.; Körfer, Reiner

2005-01-01

Abstract: Gaseous microemboli (GME) are still an unsolved problem of extracorporeal circuits. They are associated with organ injury during cardiopulmonary bypass. Microbubbles of different sizes and number are generated in the blood as the result of different components of the extracorporeal circuit as well as surgical maneuvers. The aim of our study was to observe the behavior of microporous membrane oxygenators to GME in the daily use and in an in vitro model. For the detection of microbubbles, we used a two-channel ultrasonic bubble counter based on 2-MHz Doppler-System with special ultrasound probes. The amount and size of GME were monitored before and after membrane. In 28 scheduled cases with 3 different oxygenators and variability of surgical procedures, we observed the bubble activity in the extracorporeal circuit. In addition, we used an in-vitro model to study the ability of six different oxygenators by removing air in various tests. The oxygenators tested were manufactured with different membrane technologies. The results of our investigations showed varying membrane design lead to a partial removal of GME as well as a change in size and numbers of microbubbles. PMID:16350377

Oxygen-Free Biochemistry: The Putative CHN Foundation for Exotic Life in a Hydrocarbon World?

NASA Astrophysics Data System (ADS)

Lv, Kong-Peng; Norman, Lucy; Li, Yi-Liang

2017-11-01

Since Earth's biochemistry is carbon-based and water-borne, the main strategies for searching for life elsewhere are "follow the carbon" and "follow the water." Recently, however, there is a growing focus on the prospect that putative exotic life on other planets could rely on unearthly biochemistries. Here, we hypothesize a novel oxygen-free organic chemistry for supporting potential exotic biosystems, which is named CHN biochemistry. This oxygen-free CHN biochemistry starts from simple oxygen-free species (including hydrocarbons, hydrogen cyanide, and nitriles) and produces a range of functional macromolecules that may function in similar ways to terran macromolecules, such as sugars (cyanosugars), acids (cyanoacids), amino acids (amino cyanoacids), and nucleobases (cyanonucleobases). These CHN macromolecules could further interact with each other to generate higher "cyanoester" and "cyanoprotein" systems. In addition, theoretical calculations indicate that the energy changes of some reactions are consistent with their counterparts in Earth's biochemistry. The CHN biochemistry-based life would be applicable in habitats with a low bioavailability of oxygen, such as the alkane lakes of Titan and non-aquatic liquids on extrasolar bodies.

Mechanism of Oxidative Stress in Neurodegeneration

PubMed Central

Gandhi, Sonia; Abramov, Andrey Y.

2012-01-01

Biological tissues require oxygen to meet their energetic demands. However, the consumption of oxygen also results in the generation of free radicals that may have damaging effects on cells. The brain is particularly vulnerable to the effects of reactive oxygen species due to its high demand for oxygen, and its abundance of highly peroxidisable substrates. Oxidative stress is caused by an imbalance in the redox state of the cell, either by overproduction of reactive oxygen species, or by dysfunction of the antioxidant systems. Oxidative stress has been detected in a range of neurodegenerative disease, and emerging evidence from in vitro and in vivo disease models suggests that oxidative stress may play a role in disease pathogenesis. However, the promise of antioxidants as novel therapies for neurodegenerative diseases has not been borne out in clinical studies. In this review, we critically assess the hypothesis that oxidative stress is a crucial player in common neurodegenerative disease and discuss the source of free radicals in such diseases. Furthermore, we examine the issues surrounding the failure to translate this hypothesis into an effective clinical treatment. PMID:22685618

Development of a novel proton exchange membrane-free integrated MFC system with electric membrane bioreactor and air contact oxidation bed for efficient and energy-saving wastewater treatment.

PubMed

Gao, Changfei; Liu, Lifen; Yang, Fenglin

2017-08-01

A novel combined system integrating MFC and electric membrane bioreactor (EMBR) was developed, in which a quartz sand chamber (QSC) was used, replacing expensive proton exchange membrane (PEM). An air contact oxidation bed (ACOB) and embedded trickling filter (TF) with filled volcano rock, was designed to increase dissolved oxygen (DO) in cathodic EMBR to save aeration cost. Membrane fouling in EMBR was successful inhibited/reduced by the generated bioelectricity of the system. The combined system demonstrated superior effluent quality in removing chemical oxygen demand (>97%) and ammonia nitrogen (>93%) during the stable operation, and the phosphorus removal was about 50%. Dominant bacteria (Nitrosomonas sp.; Comamonas sp.; Candidatus Kuenenia) played important roles in the removal of organic matter and ammonia nitrogen. The system has good application prospects in the efficient use of water and the development of sustainable wastewater recycling technology. Copyright © 2017. Published by Elsevier Ltd.

Activation of Oxygen and Hydrogen Peroxide by Copper(II) Coupled with Hydroxylamine for Oxidation of Organic Contaminants.

PubMed

Lee, Hongshin; Lee, Hye-Jin; Seo, Jiwon; Kim, Hyung-Eun; Shin, Yun Kyung; Kim, Jae-Hong; Lee, Changha

2016-08-02

This study reports that the combination of Cu(II) with hydroxylamine (HA) (referred to herein as Cu(II)/HA system) in situ generates H2O2 by reducing dissolved oxygen, subsequently producing reactive oxidants through the reaction of Cu(I) with H2O2. The external supply of H2O2 to the Cu(II)/HA system (i.e., the Cu(II)/H2O2/HA system) was found to further enhance the production of reactive oxidants. Both the Cu(II)/HA and Cu(II)/H2O2/HA systems effectively oxidized benzoate (BA) at pH between 4 and 8, yielding a hydroxylated product, p-hydroxybenzoate (pHBA). The addition of a radical scavenger, tert-butyl alcohol, inhibited the BA oxidation in both systems. However, electron paramagnetic resonance (EPR) spectroscopy analysis indicated that (•)OH was not produced under either acidic or neutral pH conditions, suggesting that the alternative oxidant, cupryl ion (Cu(III)), is likely a dominant oxidant.

Photophysical properties of fullerene-dendron-pyropheophorbide supramolecules

NASA Astrophysics Data System (ADS)

Ermilov, E. A.; Al-Omari, S.; Helmreich, M.; Jux, N.; Hirsch, A.; Röder, B.

2004-05-01

Two novel monofullerene-bis(pyropheophorbide a) complexes were synthesized and their photophysical properties were studied by using both steady-state and time-resolved techniques. It was revealed that in the pyropheophorbide a (pyroPheo)-C 60 molecular system (FP1) strong quenching of the first excited singlet state of the pyroPheo and, as result, dramatically decreasing of photosensitized singlet oxygen generation occurs by efficient photoinduced electron transfer to the fullerene molecule with a rate constant of 2.5 × 10 9 s -1. In contrast, the fullerene hexaadduct-bis(pyroPheo) system (FHP1), which possesses five diethyl malonate addends in the remaining octahedral positions, shows a high singlet oxygen quantum yield which is due to the reduced fullerene chromophore which is not a good electron acceptor anymore.

Impact of Photosensitizers Activation on Intracellular Trafficking and Viscosity

PubMed Central

Aubertin, Kelly; Bonneau, Stéphanie; Silva, Amanda K. A.; Bacri, Jean-Claude; Gallet, François; Wilhelm, Claire

2013-01-01

The intracellular microenvironment is essential for the efficiency of photo-induced therapies, as short-lived reactive oxygen species generated must diffuse through their intracellular surrounding medium to reach their cellular target. Here, by combining measurements of local cytoplasmic dissipation and active trafficking, we found that photosensitizers activation induced small changes in surrounding viscosity but a massive decrease in diffusion. These effects are the signature of a return to thermodynamic equilibrium of the system after photo-activation and correlated with depolymerization of the microtubule network, as shown in a reconstituted system. These mechanical measurements were performed with two intracellular photosensitizing chlorins having similar quantum yield of singlet oxygen production but different intracellular localizations (cytoplasmic for mTHPC, endosomal for TPCS2a). These two agents demonstrated different intracellular impact. PMID:24386423

Functional importance of blood flow dynamics and partial oxygen pressure in the anterior pituitary.

PubMed

Schaeffer, Marie; Hodson, David J; Lafont, Chrystel; Mollard, Patrice

2010-12-01

The pulsatile release of hormone is obligatory for the control of a range of important body homeostatic functions. To generate these pulses, endocrine organs have developed finely regulated mechanisms to modulate blood flow both to meet the metabolic demand associated with intense endocrine cell activity and to ensure the temporally precise uptake of secreted hormone into the bloodstream. With a particular focus on the pituitary gland as a model system, we review here the importance of the interplay between blood flow regulation and oxygen tensions in the functioning of endocrine systems, and the known regulatory signals involved in the modification of flow patterns under both normal physiological and pathological conditions. © 2010 The Authors. European Journal of Neuroscience © 2010 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

Nitrogen transformation of reclaimed wastewater in a pipeline by oxygen injection.

PubMed

Rodríguez-Gómez, L E; Alvarez, M; Rodríguez-Sevilla, J; Marrero, M C; Hernández, A

2009-06-01

A study of oxygen injection was performed in a completely filled gravity pipe, which is part of the South Tenerife reclaimed wastewater reuse scheme (Spain), in order to inhibit the appearance of anaerobic conditions by a nitrification-denitrification process. The pipe was 0.6 m in diameter and 62 km long and made of cast iron with a concrete inner coating, A high-pressure oxygen injection system was installed at 16 km from the pipe inlet, where severe anaerobic conditions appear. Experiments on oxygen injection were carried out with three different concentrations (7, 15 and 30 mg l(-1) O2). In all experiments, oxygen dissolved properly after injection, and no gas escapes were detected during water transportation. Most oxygen was consumed in the nitrification process, due to the low COD/NH4-N ratio, leading to a maximum production of oxidized nitrogen compounds of 7.5 mg l(-1) NO(x)-N with the 30 mg l(-1) O2 dose. Nitrification occured with nitrite accumulation, attributed to the presence of free ammonia within the range 1.2-1.4 mg l(-). Once the oxygen had been consumed, an apparent half-order denitrification took place, with limitation of biodegradable organic matter. The anoxic conditions led to a complete inhibition of sulphide generation.