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Sample records for oxygen sensor assessment

  1. An Assessment of Three Different In Situ Oxygen Sensors for Monitoring Silage Production and Storage.

    PubMed

    Shan, Guilin; Sun, Yurui; Li, Menghua; Jungbluth, Kerstin H; Maack, Christian; Buescher, Wolfgang; Schütt, Kai-Benjamin; Boeker, Peter; Lammers, Peter Schulze; Zhou, Haiyang; Cheng, Qiang; Ma, Daokun

    2015-01-01

    Oxygen (O₂) concentration inside the substrate is an important measurement for silage-research and-practical management. In the laboratory gas chromatography is commonly employed for O₂ measurement. Among sensor-based techniques, accurate and reliable in situ measurement is rare because of high levels of carbon dioxide (CO₂) generated by the introduction of O₂ in the silage. The presented study focused on assessing three types of commercial O₂ sensors, including Clark oxygen electrodes (COE), galvanic oxygen cell (GOC) sensors and the Dräger chip measurement system (DCMS). Laboratory cross calibration of O₂ versus CO₂ (each 0-15 vol.%) was made for the COE and the GOC sensors. All calibration results verified that O₂ measurements for both sensors were insensitive to CO₂. For the O₂ in situ measurement in silage, all O₂ sensors were first tested in two sealed barrels (diameter 35.7 cm; height: 60 cm) to monitor the O₂ depletion with respect to the ensiling process (Test-A). The second test (Test-B) simulated the silage unloading process by recording the O₂ penetration dynamics in three additional barrels, two covered by dry ice (0.6 kg or 1.2 kg of each) on the top surface and one without. Based on a general comparison of the experimental data, we conclude that each of these in situ sensor monitoring techniques for O₂ concentration in silage exhibit individual advantages and limitations. PMID:26784194

  2. An Assessment of Three Different In Situ Oxygen Sensors for Monitoring Silage Production and Storage

    PubMed Central

    Shan, Guilin; Sun, Yurui; Li, Menghua; Jungbluth, Kerstin H.; Maack, Christian; Buescher, Wolfgang; Schütt, Kai-Benjamin; Boeker, Peter; Schulze Lammers, Peter; Zhou, Haiyang; Cheng, Qiang; Ma, Daokun

    2016-01-01

    Oxygen (O2) concentration inside the substrate is an important measurement for silage-research and-practical management. In the laboratory gas chromatography is commonly employed for O2 measurement. Among sensor-based techniques, accurate and reliable in situ measurement is rare because of high levels of carbon dioxide (CO2) generated by the introduction of O2 in the silage. The presented study focused on assessing three types of commercial O2 sensors, including Clark oxygen electrodes (COE), galvanic oxygen cell (GOC) sensors and the Dräger chip measurement system (DCMS). Laboratory cross calibration of O2 versus CO2 (each 0–15 vol.%) was made for the COE and the GOC sensors. All calibration results verified that O2 measurements for both sensors were insensitive to CO2. For the O2 in situ measurement in silage, all O2 sensors were first tested in two sealed barrels (diameter 35.7 cm; height: 60 cm) to monitor the O2 depletion with respect to the ensiling process (Test-A). The second test (Test-B) simulated the silage unloading process by recording the O2 penetration dynamics in three additional barrels, two covered by dry ice (0.6 kg or 1.2 kg of each) on the top surface and one without. Based on a general comparison of the experimental data, we conclude that each of these in situ sensor monitoring techniques for O2 concentration in silage exhibit individual advantages and limitations. PMID:26784194

  3. Solid state oxygen sensor

    DOEpatents

    Garzon, Fernando H.; Brosha, Eric L.

    1997-01-01

    A potentiometric oxygen sensor is formed having a logarithmic response to a differential oxygen concentration while operating as a Nernstian-type sensor. Very thin films of mixed conducting oxide materials form electrode services while permitting diffusional oxygen access to the interface between the zirconia electrolyte and the electrode. Diffusion of oxygen through the mixed oxide is not rate-limiting. Metal electrodes are not used so that morphological changes in the electrode structure do not occur during extended operation at elevated temperatures.

  4. Solid state oxygen sensor

    DOEpatents

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

    1996-01-01

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

  5. Solid state oxygen sensor

    DOEpatents

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

    1996-08-06

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

  6. Solid state oxygen sensor

    DOEpatents

    Garzon, F.H.; Brosha, E.L.

    1997-12-09

    A potentiometric oxygen sensor is formed having a logarithmic response to a differential oxygen concentration while operating as a Nernstian-type sensor. Very thin films of mixed conducting oxide materials form electrode services while permitting diffusional oxygen access to the interface between the zirconia electrolyte and the electrode. Diffusion of oxygen through the mixed oxide is not rate-limiting. Metal electrodes are not used so that morphological changes in the electrode structure do not occur during extended operation at elevated temperatures. 6 figs.

  7. Oxygen partial pressure sensor

    DOEpatents

    Dees, D.W.

    1994-09-06

    A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured. 1 fig.

  8. Oxygen partial pressure sensor

    DOEpatents

    Dees, Dennis W.

    1994-01-01

    A method for detecting oxygen partial pressure and an oxygen partial pressure sensor are provided. The method for measuring oxygen partial pressure includes contacting oxygen to a solid oxide electrolyte and measuring the subsequent change in electrical conductivity of the solid oxide electrolyte. A solid oxide electrolyte is utilized that contacts both a porous electrode and a nonporous electrode. The electrical conductivity of the solid oxide electrolyte is affected when oxygen from an exhaust stream permeates through the porous electrode to establish an equilibrium of oxygen anions in the electrolyte, thereby displacing electrons throughout the electrolyte to form an electron gradient. By adapting the two electrodes to sense a voltage potential between them, the change in electrolyte conductivity due to oxygen presence can be measured.

  9. Novel nanostructured oxygen sensor

    NASA Astrophysics Data System (ADS)

    Boardman, Alan James

    New government regulations and industry requirements for medical oxygen sensors require the development of alternate materials and process optimization of primary sensor components. Current oxygen sensors are not compliant with the Restriction of Hazardous Substances (RoHS) Directive. This work focused on two areas. First, was finding suitable readily available materials for the sensor anodes. Second was optimizing the processing of the sensor cathode membrane for reduced delamination. Oxygen sensors were made using tin (Sn) and bismuth (Bi) electrodes, potassium hydroxide (KOH) and acetic acid (CH3COOH) electrolytes with platinum (Pt) and gold (Au) reference electrodes. Bi electrodes were fabricated by casting and pressing processes. Electrochemical characterization of the Sn and Bi electrodes was performed by Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS) and sensing characterization per BSEN ISO 21647:2009 at various oxygen percentages, 0%, 20.9% and 100% oxygen levels with an automated test apparatus. The Sn anode with both electrolyte solutions showed good oxygen sensing properties and performance in a sensor. This system shows promise for replacement of Pb electrodes as required by the RoHS Directive. The Bi anode with Au cathode in both KOH and CH3COOH electrolytes showed acceptable performance and oxygen sensing properties. The Bi anodes fabricated by separate manufacturing methods demonstrated effectiveness for use in medical oxygen sensors. Gold thin films were prepared by magnetron sputtering on Flouroethylene Polymer (FEP) films. The FEP substrate temperature ranged from -77°C to 50°C. X-Ray Diffraction (XRD) and 4-point resistivity characterized the effects of substrate temperature to Au thin film particle size. XRD peak broadening and resistivity measurements showed a strong correlation of particle size to FEP substrate temperature. Particle size at 50°C was 594A and the -77°C particle size was 2.4 x 103A. Substrate

  10. An Assessment of the Influence of the Industry Distribution Chain on the Oxygen Levels in Commercial Modified Atmosphere Packaged Cheddar Cheese Using Non-Destructive Oxygen Sensor Technology.

    PubMed

    O' Callaghan, Karen A M; Papkovsky, Dmitri B; Kerry, Joseph P

    2016-01-01

    The establishment and control of oxygen levels in packs of oxygen-sensitive food products such as cheese is imperative in order to maintain product quality over a determined shelf life. Oxygen sensors quantify oxygen concentrations within packaging using a reversible optical measurement process, and this non-destructive nature ensures the entire supply chain can be monitored and can assist in pinpointing negative issues pertaining to product packaging. This study was carried out in a commercial cheese packaging plant and involved the insertion of 768 sensors into 384 flow-wrapped cheese packs (two sensors per pack) that were flushed with 100% carbon dioxide prior to sealing. The cheese blocks were randomly assigned to two different storage groups to assess the effects of package quality, packaging process efficiency, and handling and distribution on package containment. Results demonstrated that oxygen levels increased in both experimental groups examined over the 30-day assessment period. The group subjected to a simulated industrial distribution route and handling procedures of commercial retailed cheese exhibited the highest level of oxygen detected on every day examined and experienced the highest rate of package failure. The study concluded that fluctuating storage conditions, product movement associated with distribution activities, and the possible presence of cheese-derived contaminants such as calcium lactate crystals were chief contributors to package failure. PMID:27331815

  11. An Assessment of the Influence of the Industry Distribution Chain on the Oxygen Levels in Commercial Modified Atmosphere Packaged Cheddar Cheese Using Non-Destructive Oxygen Sensor Technology

    PubMed Central

    O’ Callaghan, Karen A.M.; Papkovsky, Dmitri B.; Kerry, Joseph P.

    2016-01-01

    The establishment and control of oxygen levels in packs of oxygen-sensitive food products such as cheese is imperative in order to maintain product quality over a determined shelf life. Oxygen sensors quantify oxygen concentrations within packaging using a reversible optical measurement process, and this non-destructive nature ensures the entire supply chain can be monitored and can assist in pinpointing negative issues pertaining to product packaging. This study was carried out in a commercial cheese packaging plant and involved the insertion of 768 sensors into 384 flow-wrapped cheese packs (two sensors per pack) that were flushed with 100% carbon dioxide prior to sealing. The cheese blocks were randomly assigned to two different storage groups to assess the effects of package quality, packaging process efficiency, and handling and distribution on package containment. Results demonstrated that oxygen levels increased in both experimental groups examined over the 30-day assessment period. The group subjected to a simulated industrial distribution route and handling procedures of commercial retailed cheese exhibited the highest level of oxygen detected on every day examined and experienced the highest rate of package failure. The study concluded that fluctuating storage conditions, product movement associated with distribution activities, and the possible presence of cheese-derived contaminants such as calcium lactate crystals were chief contributors to package failure. PMID:27331815

  12. Integrated-Optic Oxygen Sensors

    NASA Technical Reports Server (NTRS)

    Mendoza, Edgar A.; Lieberman, Robert A.

    2004-01-01

    Compact optical oxygen sensors with self-calibration capabilities are undergoing development. A sensor of this type features a single-chip, integrated-optic design implemented by photolithographic fabrication of optical waveguides in a photosensitive porous glass. The porosity serves as both a matrix for retention of an oxygen-sensitive fluorescent indicator chemical and a medium for diffusion of oxygen to the chemical from the ambient air to be monitored. Each sensor includes at least one such waveguide exposed to the atmosphere and at least one covered with metal for isolation from the atmosphere. The covered one serves as a reference channel. In operation, the concentration of oxygen is deduced from the intensity and lifetime of the fluorescence in the exposed channel, with the help of calibration data acquired via the reference channel. Because the sensory chemical is placed directly in and throughout the cross section of the light path, approximately 99 percent of the light in the waveguide is available for interaction with the chemical, in contradistinction to only about 1 percent of the light in an optical sensor that utilizes evanescentwave coupling. Hence, a sensor of this type is significantly more sensitive.

  13. Development of self-tuning residential oil-burner. Oxygen sensor assessment and early prototype system operating experience

    SciTech Connect

    McDonald, R.J.; Butcher, T.A.; Krajewski, R.F.

    1998-09-01

    This document is the first topical report dealing with a new project leading towards the development of a self-tuning residential oil burner. It was initiated under the Statement of Work for the Oil Heat Research and Development Program, for Fiscal Year 1997 as defined in the Combustion Equipment Technology Program, under the management of Brookhaven National Laboratory (BNL). In part, this work is based on research reported by BNL in 1990, suggesting various options for developing control strategies in oil heat technology leading to the enhanced efficiency of oil-fired heating systems. BNL has been addressing these concepts in order of priority and technology readiness. The research described in this report is part of an ongoing project and additional work is planned for the future assuming adequate program funding is made available. BNL has continued to investigate all types of sensor technologies associated with combustion systems including all forms of oxygen measurement techniques. In these studies the development of zirconium oxide oxygen sensors has been considered over the last decade. The development of these sensors for the automotive industry has allowed for cost reductions based on quantity of production that might not have occurred otherwise. This report relates BNL`s experience in testing various zirconium oxide sensors, and the results of tests intended to provide evaluation of the various designs with regard to performance in oil-fired systems. These tests included accuracy when installed on oil-fired heating appliances and response time in cyclic operating mode. An evaluation based on performance criteria and cost factors was performed. Cost factors in the oil heat industry are one of the most critical issues in introducing new technology.

  14. Electrochemical Oxygen Sensor Development for Liquid Sodium

    NASA Astrophysics Data System (ADS)

    Nollet, Billy K.

    Safe operation of a sodium-cooled fast reactor (SFR) requires in-depth understanding of the corrosion implications of liquid sodium coolant on reactor materials. Dissolved oxygen concentration is of particular importance in characterizing sodium attack, so an accurate means of measuring and controlling oxygen is crucial. There is significant room for improvement in current oxygen sensing technology, so extensive research has been conducted at the University of Wisconsin-Madison to address this issue. Experimental facilities and electrochemical oxygen sensors have been developed, tested, and analyzed. This research is discussed in detail in this report. The oxygen sensors tested in this research were developed using a yttria stabilized zirconia (YSZ) electrolyte whereas many of the past research in this field was conducted with yttria doped thoria (YDT or YST) electrolytes. Thorium, an alpha emitter, is expensive and increasingly difficult to acquire, so motivation to switch to a new material exists. YSZ is commonly used as the electrolyte for solid oxide fuel cells, and ample data is available for high temperature ionic conduction of this material. While some work has been done with YSZ in oxygen sensors (the automotive field, for example, uses YSZ O2 sensors), research on YSZ sensors in sodium is limited. A thorough study of YSZ-based electrochemical oxygen sensors must include detailed corrosion testing and analysis of YSZ in liquid sodium, careful oxygen sensor development and testing, and finally, a comprehensive analysis of the acquired sensor data. The research presented in this report describes the design and development of an electrochemical oxygen sensor for use in sodium using a YSZ electrolyte through the previously-mentioned steps. The designed sensors were subjected to a series of hypotheses which advance common understanding of oxygen sensor signal. These results were used in conjunction with past research to form reliable conclusions.

  15. Nanomaterial-based robust oxygen sensor

    NASA Astrophysics Data System (ADS)

    Goswami, Kisholoy; Sampathkumaran, Uma; Alam, Maksudul; Tseng, Derek; Majumdar, Arun K.; Kazemi, Alex A.

    2007-09-01

    Since the TWA flight 800 accident in July 1996, significant emphasis has been placed on fuel tank safety. The Federal Aviation Administration (FAA) has focused research to support two primary methods of fuel tank protection - ground-based and on-board - both involving fuel tank inerting. Ground-based fuel tank inerting involves some combination of fuel scrubbing and ullage washing with Nitrogen Enriched Air (NEA) while the airplane is on the ground (applicable to all or most operating transport airplanes). On-board fuel tank inerting involves ullage washing with OBIGGS (on-board inert gas generating system), a system that generates NEA during aircraft operations. An OBIGGS generally encompasses an air separation module (ASM) to generate NEA, a compressor, storage tanks, and a distribution system. Essential to the utilization of OBIGGS is an oxygen sensor that can operate inside the aircraft's ullage and assess the effectiveness of the inerting systems. OBIGGS can function economically by precisely knowing when to start and when to stop. Toward achieving these goals, InnoSense LLC is developing an all-optical fuel tank ullage sensor (FTUS) prototype for detecting oxygen in the ullage of an aircraft fuel tank in flight conditions. Data would be presented to show response time and wide dynamic range of the sensor in simulated flight conditions and fuel tank environment.

  16. Calibration Of Partial-Pressure-Of-Oxygen Sensors

    NASA Technical Reports Server (NTRS)

    Yount, David W.; Heronimus, Kevin

    1995-01-01

    Report and analysis of, and discussion of improvements in, procedure for calibrating partial-pressure-of-oxygen sensors to satisfy Spacelab calibration requirements released. Sensors exhibit fast drift, which results in short calibration period not suitable for Spacelab. By assessing complete process of determining total drift range available, calibration procedure modified to eliminate errors and still satisfy requirements without compromising integrity of system.

  17. Assessment of tissue oxygenation.

    PubMed

    Robertson, P W; Hart, B B

    1999-06-01

    A continuous supply of oxygen to all tissues is necessary for the efficient production of ATP, and this supply is considered sufficient when aerobic metabolism is maintained. Nonhealing wounds, necrotizing infections, radiation-induced necrosis, crush injury, decompression illness, and CO poisoning all exhibit impaired tissue oxygenation. The need for efficacy of HBO therapy in such conditions is in part determined by the prevailing state of tissue oxygen supply and demand. The methods currently available or under development for assessing the adequacy of tissue oxygenation include blood gas analysis, transcutaneous oxygen measurement, gastric tonometry, pulse oximetry, near-infrared spectroscopy, functional MR imaging, MR spectroscopy, electron paramagnetic resonance, positron emission tomography, and single photon emission computed tomography. The clinical and experimental applications of these methods are discussed and emphasis is placed on their role in hyperbaric medicine. PMID:10333450

  18. Silver electrodes for reversible oxygen sensor applications

    NASA Astrophysics Data System (ADS)

    Kim, Taekyeong

    2015-09-01

    We report a single oxygen atomic sensor based on a scanning tunneling microscope break-junction (STM-BJ) technique by using silver electrodes at room temperature. The oxygen concentration was adjusted with argon gas in a glove box. An oxygen atom was inserted in the gap of the Ag electrodes after the Ag metal point contact had been ruptured during stretching of the Ag atomic junctions by moving a piezo. We successfully measured the conductance of a single oxygen atom by forming a series with the Ag contact, Ag-O-Ag bond. We found that the probability of Ag-O-Ag junction formation increased with increasing oxygen concentration. Furthermore, we observed that the peak height in the oxygen conductance histogram was changed reversibly depending on the oxygen concentration in a glove box. It confirms that our STM-BJ can be used for atomic sensor applications in the future.

  19. Surface acoustic wave oxygen sensor

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  20. Resistive Oxygen Gas Sensors for Harsh Environments

    PubMed Central

    Moos, Ralf; Izu, Noriya; Rettig, Frank; Reiß, Sebastian; Shin, Woosuck; Matsubara, Ichiro

    2011-01-01

    Resistive oxygen sensors are an inexpensive alternative to the classical potentiometric zirconia oxygen sensor, especially for use in harsh environments and at temperatures of several hundred °C or even higher. This device-oriented paper gives a historical overview on the development of these sensor materials. It focuses especially on approaches to obtain a temperature independent behavior. It is shown that although in the past 40 years there have always been several research groups working concurrently with resistive oxygen sensors, novel ideas continue to emerge today with respect to improvements of the sensor response time, the temperature dependence, the long-term stability or the manufacture of the devices themselves using novel techniques for the sensitive films. Materials that are the focus of this review are metal oxides; especially titania, titanates, and ceria-based formulations. PMID:22163805

  1. Determining Performance Acceptability of Electrochemical Oxygen Sensors

    NASA Technical Reports Server (NTRS)

    Gonzales, Daniel

    2012-01-01

    A method has been developed to screen commercial electrochemical oxygen sensors to reduce the failure rate. There are three aspects to the method: First, the sensitivity over time (several days) can be measured and the rate of change of the sensitivity can be used to predict sensor failure. Second, an improvement to this method would be to store the sensors in an oxygen-free (e.g., nitrogen) environment and intermittently measure the sensitivity over time (several days) to accomplish the same result while preserving the sensor lifetime by limiting consumption of the electrode. Third, the second time derivative of the sensor response over time can be used to determine the point in time at which the sensors are sufficiently stable for use.

  2. High Temperature Langasite SAW Oxygen Sensor

    SciTech Connect

    Zheng, Peng; Chin, Tao-Lun; Greve, David; Oppenheim, Irving; Malone, Vanessa; Cao, Limin

    2011-08-01

    High-temperature langasite SAW oxygen sensors using sputtered ZnO as a resistive gas-sensing layer were fabricated and tested. Sensitivity to oxygen gas was observed between 500°C to 700°C, with a sensitivity peak at about 625°C, consistent with the theoretical predictions of the acoustoelectric effect.

  3. EVALUATING AN INNOVATIVE OXYGEN SENSOR FOR REMOTE SUBSURFACE OXYGEN MEASUREMENTS

    SciTech Connect

    Millings, M; Brian Riha, B; Warren Hyde, W; Karen Vangelas, K; Brian02 Looney, B

    2006-10-12

    Oxygen is a primary indicator of whether anaerobic reductive dechlorination and similar redox based processes contribute to natural attenuation remedies at chlorinated solvent contaminated sites. Thus, oxygen is a viable indicator parameter for documenting that a system is being sustained in an anaerobic condition. A team of researchers investigated the adaptation of an optical sensor that was developed for oceanographic applications. The optical sensor, because of its design and operating principle, has potential for extended deployment and sensitivity at the low oxygen levels relevant to natural attenuation. The results of the research indicate this tool will be useful for in situ long-term monitoring applications, but that the traditional characterization tools continue to be appropriate for characterization activities.

  4. Bimodular high temperature planar oxygen gas sensor.

    PubMed

    Sun, Xiangcheng; Liu, Yixin; Gao, Haiyong; Gao, Pu-Xian; Lei, Yu

    2014-01-01

    A bimodular planar O2 sensor was fabricated using NiO nanoparticles (NPs) thin film coated yttria-stabilized zirconia (YSZ) substrate. The thin film was prepared by radio frequency (r.f.) magnetron sputtering of NiO on YSZ substrate, followed by high temperature sintering. The surface morphology of NiO NPs film was characterized by atomic force microscope (AFM) and scanning electron microscope (SEM). X-ray diffraction (XRD) patterns of NiO NPs thin film before and after high temperature O2 sensing demonstrated that the sensing material possesses a good chemical and structure stability. The oxygen detection experiments were performed at 500, 600, and 800°C using the as-prepared bimodular O2 sensor under both potentiometric and resistance modules. For the potentiometric module, a linear relationship between electromotive force (EMF) output of the sensor and the logarithm of O2 concentration was observed at each operating temperature, following the Nernst law. For the resistance module, the logarithm of electrical conductivity was proportional to the logarithm of oxygen concentration at each operating temperature, in good agreement with literature report. In addition, this bimodular sensor shows sensitive, reproducible and reversible response to oxygen under both sensing modules. Integration of two sensing modules into one sensor could greatly enrich the information output and would open a new venue in the development of high temperature gas sensors. PMID:25191652

  5. Bimodular high temperature planar oxygen gas sensor

    PubMed Central

    Sun, Xiangcheng; Liu, Yixin; Gao, Haiyong; Gao, Pu-Xian; Lei, Yu

    2014-01-01

    A bimodular planar O2 sensor was fabricated using NiO nanoparticles (NPs) thin film coated yttria-stabilized zirconia (YSZ) substrate. The thin film was prepared by radio frequency (r.f.) magnetron sputtering of NiO on YSZ substrate, followed by high temperature sintering. The surface morphology of NiO NPs film was characterized by atomic force microscope (AFM) and scanning electron microscope (SEM). X-ray diffraction (XRD) patterns of NiO NPs thin film before and after high temperature O2 sensing demonstrated that the sensing material possesses a good chemical and structure stability. The oxygen detection experiments were performed at 500, 600, and 800°C using the as-prepared bimodular O2 sensor under both potentiometric and resistance modules. For the potentiometric module, a linear relationship between electromotive force (EMF) output of the sensor and the logarithm of O2 concentration was observed at each operating temperature, following the Nernst law. For the resistance module, the logarithm of electrical conductivity was proportional to the logarithm of oxygen concentration at each operating temperature, in good agreement with literature report. In addition, this bimodular sensor shows sensitive, reproducible and reversible response to oxygen under both sensing modules. Integration of two sensing modules into one sensor could greatly enrich the information output and would open a new venue in the development of high temperature gas sensors. PMID:25191652

  6. Hydrogen and oxygen sensor development

    NASA Technical Reports Server (NTRS)

    Farber, E. A.; Mahig, J.; Schaeper, H. R. A.

    1972-01-01

    A reliable and low cost gas sensor was investigated for instantaneously detecting H2 in N2, H2 in air, and O2 in N2. The major portion of the research was spent in developing a sensor which would instantaneously detect H2 to + or - 50 ppm even in the presence of trace amounts of other gases. The experimental procedures used to provide the performance characteristics for the various oscillators are discussed describing the equipment with help of schematics and photographs where applicable. The resulting performance is given in graphical form. In some cases both hydrogen and helium may be present and since both of them effect gas sensors similarly, a method was found to determine the concentration of each. The methods developed are grouped into the following four broad categories: pure metal response, variation in heat conductivity, reduction methods, and exotic processes. From the above it was decided for the present to use a copper oxide reduction process as this process was demonstrated to be capable of determining the concentrations of hydrogen and helium respectively in a gas mixture with air or nitrogen.

  7. Thin film oxygen partial pressure sensor

    NASA Technical Reports Server (NTRS)

    Wortman, J. J.; Harrison, J. W.; Honbarrier, H. L.; Yen, J.

    1972-01-01

    The development is described of a laboratory model oxygen partial pressure sensor using a sputtered zinc oxide thin film. The film is operated at about 400 C through the use of a miniature silicon bar. Because of the unique resistance versus temperature relation of the silicon bar, control of the operational temperature is achieved by controlling the resistance. A circuit for accomplishing this is described. The response of sputtered zinc oxide films of various thicknesses to oxygen, nitrogen, argon, carbon dioxide, and water vapor caused a change in the film resistance. Over a large range, film conductance varied approximately as the square root of the oxygen partial pressure. The presence of water vapor in the gas stream caused a shift in the film conductance at a given oxygen partial pressure. A theoretical model is presented to explain the characteristic features of the zinc oxide response to oxygen.

  8. Nanofiber Based Optical Sensors for Oxygen Determination

    NASA Astrophysics Data System (ADS)

    Xue, Ruipeng

    Oxygen sensors based on luminescent quenching of nanofibers were developed for measurement of both gaseous and dissolved oxygen concentrations. Electrospinning was used to fabricate "core-shell" fiber configurations in which oxygen-sensitive transition metal complexes are embedded into a polymer 'core' while a synthetic biocompatible polymer provides a protective 'shell.' Various matrix polymers and luminescent probes were studied in terms of their sensitivity, linear calibration, reversibility, response time, stability and probe-matrix interactions. Due to the small size and high surface area of these nanofibers, all samples showed rapid response and a highly linear response to oxygen. The sensitivity and photostability of the sensors were controlled by the identity of both the probe molecule and the polymer matrix. Such nanofiber sensor forms are particularly suitable in biological applications due to the fact that they do not consume oxygen, are biocompatible and biomimetic and can be easily incorporated into cell culture. Applications of these fibers in cancer cell research, wound healing, breath analysis and waste water treatment were explored.

  9. 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.

  10. A water-soluble luminescence oxygen sensor.

    PubMed

    Castellano, F N; Lakowicz, J R

    1998-02-01

    We developed a water-soluble luminescent probe for dissolved oxygen. This probe is based on (Ru[dpp(SO3Na)2]3) cl2, which is a sulfonated analogue of the well-known oxygen probe (Ru[dpp]3)cl2. The compound dpp is 4,7-diphenyl-1,10-phenanthroline and dpp(SO3Na)2 is a disulfonated derivative of the same ligand. In aqueous solution in the absence of oxygen (Ru[dpp(SO3Na)2]3)cl2 displays a lifetime of 3.7 microseconds that decreases to 930 ns on equilibrium with air and 227 ns on equilibrium with 100% oxygen. The Stern-Volmer quenching constant is 11,330 M-1. This high oxygen-quenching constant means that the photoluminescence of Ru(dpp[SO3Na]2)3cl2 is 10% quenched at an oxygen concentration of 8.8 x 10(-6) M, or equilibration with 5.4 torr of oxygen. The oxygen probe dissolved in water displays minimal interactions with lipid vesicles composed of dipalmityl-L-alpha-phosphatidyl glycerol but does appear to interact with human serum albumin. The absorption maximum near 480 nm, long lifetime and large Stokes' shift allow this probe to be used with simple instrumentation based on a light-emitting diode light source, allowing low-cost oxygen sensing in aqueous solutions. To the best of our knowledge this is the first practical water-soluble oxygen sensor. PMID:9487796

  11. Oxygen sensors and energy sensors act synergistically to achieve a graded alteration in gene expression: consequences for assessing the level of neuroprotection in response to stressors.

    PubMed

    Renshaw, Gillian M C; Warburton, Joshua; Girjes, Adeeb

    2004-01-01

    Changes in gene expression are associated with switching to an autoprotected phenotype in response to environmental and physiological stress. Ubiquitous molecular chaperones from the heat shock protein (HSP) superfamily confer neuronal protection that can be blocked by antibodies. Recent research has focused on the interactions between the molecular sensors that affect the increased expression of neuroprotective HSPs above constitutive levels. An examination of the conditions under which the expression of heat shock protein 70 (Hsp70) was up regulated in a hypoxia and anoxia tolerant tropical species, the epaulette shark (Hemiscyllium ocellatum), revealed that up-regulation was dependent on exceeding a stimulus threshold for an oxidative stressor. While hypoxic-preconditioning confers neuroprotective changes, there was no increase in the level of Hsp70 indicating that its increased expression was not associated with achieving a neuroprotected state in response to hypoxia in the epaulette shark. Conversely, there was a significant increase in Hsp70 in response to anoxic-preconditioning, highlighting the presence of a stimulus threshold barrier and raising the possibility that, in this species, Hsp70 contributes to the neuroprotective response to extreme crises, such as oxidative stress. Interestingly, there was a synergistic effect of coincident stressors on Hsp70 expression, which was revealed when metabolic stress was superimposed upon oxidative stress. Brain energy charge was significantly lower when adenosine receptor blockade, provided by treatment with aminophylline, was present prior to the final anoxic episode, under these circumstances, the level of Hsp70 induced was significantly higher than in the pair-matched saline treated controls. An understanding of the molecular and metabolic basis for neuroprotective switches, which result in an up-regulation of neuroprotective Hsp70 expression in the brain, is needed so that intervention strategies can be devised

  12. New electrolyte may increase life of polarographic oxygen sensors

    NASA Technical Reports Server (NTRS)

    Albright, C. F.

    1967-01-01

    Electrolyte increases life on oxygen sensors in a polarograph used for measuring the partial pressure of oxygen in a gas mixture. It consists of a solution of lithium chloride, dimethyl acetamide and water.

  13. Enzymatic Glucose Sensor Compensation for Variations in Ambient Oxygen Concentration

    PubMed Central

    Collier, Bradley B.; McShane, Michael J.

    2014-01-01

    Due to the increasing prevalence of diabetes, research toward painless glucose sensing continues. Oxygen sensitive phosphors with glucose oxidase (GOx) can be used to determine glucose levels indirectly by monitoring oxygen consumption. This is an attractive combination because of its speed and specificity. Packaging these molecules together in “smart materials” for implantation will enable non-invasive glucose monitoring. As glucose levels increase, oxygen levels decrease; consequently, the luminescence intensity and lifetime of the phosphor increase. Although the response of the sensor is dependent on glucose concentration, the ambient oxygen concentration also plays a key role. This could lead to inaccurate glucose readings and increase the risk of hyper- or hypoglycemia. To mitigate this risk, the dependence of hydrogel glucose sensor response on oxygen levels was investigated and compensation methods explored. Sensors were calibrated at different oxygen concentrations using a single generic logistic equation, such that trends in oxygen-dependence were determined as varying parameters in the equation. Each parameter was found to be a function of oxygen concentration, such that the correct glucose calibration equation can be calculated if the oxygen level is known. Accuracy of compensation will be determined by developing an overall calibration, using both glucose and oxygen sensors in parallel, correcting for oxygen fluctuations in real time by intentionally varying oxygen, and calculating the error in actual and predicted glucose levels. While this method was developed for compensation of enzymatic glucose sensors, in principle it can also be implemented with other kinds of sensors utilizing oxidases. PMID:26257458

  14. Oxygen Sensors Monitor Bioreactors and Ensure Health and Safety

    NASA Technical Reports Server (NTRS)

    2014-01-01

    In order to cultivate healthy bacteria in bioreactors, Kennedy Space Center awarded SBIR funding to Needham Heights, Massachusetts-based Polestar Technologies Inc. to develop sensors that could monitor oxygen levels. The result is a sensor now widely used by pharmaceutical companies and medical research universities. Other sensors have also been developed, and in 2013 alone the company increased its workforce by 50 percent.

  15. Analytical sensor redundancy assessment

    NASA Technical Reports Server (NTRS)

    Mulcare, D. B.; Downing, L. E.; Smith, M. K.

    1988-01-01

    The rationale and mechanization of sensor fault tolerance based on analytical redundancy principles are described. The concept involves the substitution of software procedures, such as an observer algorithm, to supplant additional hardware components. The observer synthesizes values of sensor states in lieu of their direct measurement. Such information can then be used, for example, to determine which of two disagreeing sensors is more correct, thus enhancing sensor fault survivability. Here a stability augmentation system is used as an example application, with required modifications being made to a quadruplex digital flight control system. The impact on software structure and the resultant revalidation effort are illustrated as well. Also, the use of an observer algorithm for wind gust filtering of the angle-of-attack sensor signal is presented.

  16. An oxygen pressure sensor using surface acoustic wave devices

    NASA Technical Reports Server (NTRS)

    Leighty, Bradley D.; Upchurch, Billy T.; Oglesby, Donald M.

    1993-01-01

    Surface acoustic wave (SAW) piezoelectric devices are finding widespread applications in many arenas, particularly in the area of chemical sensing. We have developed an oxygen pressure sensor based on coating a SAW device with an oxygen binding agent which can be tailored to provide variable sensitivity. The coating is prepared by dissolving an oxygen binding agent in a toluene solution of a copolymer which is then sprayed onto the surface of the SAW device. Experimental data shows the feasibility of tailoring sensors to measure the partial pressure of oxygen from 2.6 to 67 KPa (20 to 500 torr). Potential applications of this technology are discussed.

  17. Hydrogen Sulfide as an Oxygen Sensor

    PubMed Central

    2015-01-01

    Abstract Significance Although oxygen (O2)-sensing cells and tissues have been known for decades, the identity of the O2-sensing mechanism has remained elusive. Evidence is accumulating that O2-dependent metabolism of hydrogen sulfide (H2S) is this enigmatic O2 sensor. Recent Advances The elucidation of biochemical pathways involved in H2S synthesis and metabolism have shown that reciprocal H2S/O2 interactions have been inexorably linked throughout eukaryotic evolution; there are multiple foci by which O2 controls H2S inactivation, and the effects of H2S on downstream signaling events are consistent with those activated by hypoxia. H2S-mediated O2 sensing has been demonstrated in a variety of O2-sensing tissues in vertebrate cardiovascular and respiratory systems, including smooth muscle in systemic and respiratory blood vessels and airways, carotid body, adrenal medulla, and other peripheral as well as central chemoreceptors. Critical Issues Information is now needed on the intracellular location and stoichometry of these signaling processes and how and which downstream effectors are activated by H2S and its metabolites. Future Directions Development of specific inhibitors of H2S metabolism and effector activation as well as cellular organelle-targeted compounds that release H2S in a time- or environmentally controlled way will not only enhance our understanding of this signaling process but also provide direction for future therapeutic applications. Antioxid. Redox Signal. 22, 377–397. “Nothing in Biology Makes Sense Except in the Light of Evolution” —Theodosius Dobzhansky (29) PMID:24801248

  18. A Pyrene@Micelle Sensor for Fluorescent Oxygen Sensing

    PubMed Central

    Yuan, Yan-xia; Peng, Hong-shang; Ping, Jian-tao; Wang, Xiao-hui; You, Fang-tian

    2015-01-01

    For most fluorescent oxygen sensors developed today, their fabrication process is either time-consuming or needs specialized knowledge. In this work, a robust fluorescent oxygen sensor is facilely constructed by dissolving pyrene molecules into CTAB aqueous solution. The as-prepared pyrene@micelle sensors have submicron-sized diameter, and the concentration of utilized pyrene can be reduced as low as 0.8 mM but still can exhibit dominant excimer emission. The excimer fluorescence is sensitive to dissolved oxygen in both intensity and lifetime, and the respective Stern-Volmer plot follows a nonlinear behavior justified by a two-site model. Because of the merits of large Stokes shift (~140 nm), easy fabrication, and robustness, the pyrene@micelle sensors are very attractive for practical determination of oxygen. PMID:26539471

  19. Quantum dots as a possible oxygen sensor

    NASA Astrophysics Data System (ADS)

    Ziółczyk, Paulina; Kur-Kowalska, Katarzyna; Przybyt, Małgorzata; Miller, Ewa

    Results of studies on optical properties of low toxicity quantum dots (QDs) obtained from copper doped zinc sulfate are discussed in the paper. The effect of copper admixture concentration and solution pH on the fluorescence emission intensity of QDs was investigated. Quenching of QDs fluorescence by oxygen was reported and removal of the oxygen from the environment by two methods was described. In the chemical method oxygen was eliminated by adding sodium sulfite, in the other method oxygen was removed from the solution using nitrogen gas. For elimination of oxygen by purging the solution with nitrogen the increase of fluorescence intensity with decreasing oxygen concentration obeyed Stern-Volmer equation indicating quenching. For the chemical method Stern-Volmer equation was not fulfilled. The fluorescence decays lifetimes were determined and the increase of mean lifetimes at the absence of oxygen support hypothesis that QDs fluorescence is quenched by oxygen.

  20. Nanoporous nanocrystalline monoclinic zirconia for luminescent oxygen sensors

    NASA Astrophysics Data System (ADS)

    Fidelus, Janusz D.; Zhou, Wuzong; Tenderenda, Tadeusz; Nasiłowski, Tomasz

    2015-09-01

    In this work we present a nanocrystalline monoclinic ZrO2 with large free volumen open towards the nanocrystals surface dedicated for optical oxygen sensors. Nanoporous zirconia nanopowder was fabricated in hydrothermal microwave-driven process followed by annealing at 800°C. Metal-coated optical fibers are proposed as a light carrier when the working temperature exceeds 500°C. The obtained results may also find application in luminescent fiber optic oxygen sensors.

  1. Guide for Oxygen Compatibility Assessments on Oxygen Components and Systems

    NASA Technical Reports Server (NTRS)

    Rosales, Keisa R.; Shoffstall, Michael S.; Stoltzfus, Joel M.

    2007-01-01

    A viewgraph presentation evaluating the compatibility of oxygen components and systems is shown. The topics include: 1) Application; 2) Gaining Wide Subscription; 3) Approach; 4) Establish Worst-Case Operating Conditions; 5) Assess Materials Flammability; 6) Evaluate Ignition Mechanisms; 7) Evaluate Kindling Chain; 8) Determine Reaction Affect; 9) Document Results; 10) Example of Documentation; and 11) Oxygen Compatibility Assessment Team.

  2. Quality assessment of packaged foods by optical oxygen sensing

    NASA Astrophysics Data System (ADS)

    Papkovsky, Dmitri B.; O'Mahony, Fiach C.; Kerry, Joe P.; Ogurtsov, Vladimir I.

    2005-11-01

    A phase-fluorometric oxygen sensor system has been developed, which allows non-destructive measurement of residual oxygen levels in sealed containers such as packaged foods. It operates with disposable solid-state sensors incorporated in each pack, and a portable detector which interrogates with the sensors through a (semi)transparent packaging material. The system has been optimized for packaging applications and validated in small and medium scale trials with different types of food, including MAP hams, cheese, convenience foods, smoked fish, bakery. It has demonstrated high efficiency in monitoring package integrity, oxygen profiles in packs, performance of packaging process and many other research and quality control tasks, allowing control of 100% of packs. The low-cost batch-calibrated sensors have demonstrated reliability, safety, stability including direct contact with food, high efficiency in the low oxygen range. Another system, which also employs the fluorescence-based oxygen sensing approach, provides rapid assessment of microbial contamination (total viable counts) in complex samples such as food homogenates, industrial waste, environmental samples, etc. It uses soluble oxygen-sensitive probes, standard microtitter plates and fluorescence measurements on conventional plate reader to monitor growth of aerobic bacteria in small test samples (e.g. food homogenates) via their oxygen respiration. The assay provides high sample through put, miniaturization, speed, and can serve as alternative to the established methods such as agar plate colony counts and turbidimetry.

  3. Thin film devices used as oxygen partial pressure sensors

    NASA Technical Reports Server (NTRS)

    Canady, K. S.; Wortman, J. J.

    1970-01-01

    Electrical conductivity of zinc oxide films to be used in an oxygen partial pressure sensor is measured as a function of temperature, oxygen partial pressure, and other atmospheric constituents. Time response following partial pressure changes is studied as a function of temperature and environmental changes.

  4. Optical Oxygen Sensors for Applications in Microfluidic Cell Culture

    PubMed Central

    Grist, Samantha M.; Chrostowski, Lukas; Cheung, Karen C.

    2010-01-01

    The presence and concentration of oxygen in biological systems has a large impact on the behavior and viability of many types of cells, including the differentiation of stem cells or the growth of tumor cells. As a result, the integration of oxygen sensors within cell culture environments presents a powerful tool for quantifying the effects of oxygen concentrations on cell behavior, cell viability, and drug effectiveness. Because microfluidic cell culture environments are a promising alternative to traditional cell culture platforms, there is recent interest in integrating oxygen-sensing mechanisms with microfluidics for cell culture applications. Optical, luminescence-based oxygen sensors, in particular, show great promise in their ability to be integrated with microfluidics and cell culture systems. These sensors can be highly sensitive and do not consume oxygen or generate toxic byproducts in their sensing process. This paper presents a review of previously proposed optical oxygen sensor types, materials and formats most applicable to microfluidic cell culture, and analyzes their suitability for this and other in vitro applications. PMID:22163408

  5. Pulse oximetry optical sensor using oxygen-bound haemoglobin.

    PubMed

    Cohen, Z J V; Haxha, S; Aggoun, A

    2016-05-01

    In this paper we report a unique approach to measuring oxygen saturation levels by utilising the wavelength of the haemoglobin instead of the conventional absorption difference. Two experiments are set up to measure the wavelength of the haemoglobin bound to oxygen at different oxygen saturation levels with the help of a spectrometer. We report a unique low cost and robust wavelength monitoring SpO2 sensor that measures the SpO2 by using the colour of the blood and not the absorption difference of oxyhaemoglobin and deoxyhaemoglobin. With use of a spectrometer, we show that the wavelength of the oxygen-bound haemoglobin has a relation to the oxygen saturation level. The proposed device is designed and experimentally implemented with a colour sensor to measure the SpO2 level of the blood. PMID:27137621

  6. Guide for Oxygen Compatibility Assessments on Oxygen Components and Systems

    NASA Technical Reports Server (NTRS)

    Rosales, Keisa R.; Shoffstall, Michael S.; Stoltzfus, Joel M.

    2007-01-01

    Understanding and preventing fire hazards is necessary when designing, maintaining, and operating oxygen systems. Ignition risks can be minimized by controlling heat sources and using materials that will not ignite or will not support burning in the end-use environment. Because certain materials are more susceptible to ignition in oxygen-enriched environments, a compatibility assessment should be performed before the component is introduced into an oxygen system. This document provides an overview of oxygen fire hazards and procedures that are consistent with the latest versions of American Society for Testing and Materials (ASTM) Standards G63 (1999) and G94 (2005) to address fire hazards associated with oxygen systems. This document supersedes the previous edition, NASA Technical Memorandum 104823, Guide for Oxygen Hazards Analyses on Components and Systems (1996). The step-by-step oxygen compatibility assessment method described herein (see Section 4) enables oxygen-system designers, system engineers, and facility managers to determine areas of concern with respect to oxygen compatibility and, ultimately, prevent damage to a system or injury to personnel.

  7. In vitro performance of a perfusion and oxygenation optical sensor using a unique liver phantom

    NASA Astrophysics Data System (ADS)

    Akl, Tony J.; King, Travis J.; Long, Ruiqi; Ericson, M. N.; Wilson, Mark A.; McShane, Michael J.; Coté, Gerard L.

    2012-03-01

    Between the years 1999 and 2008, on average 2,052 people died per year on the waiting list for liver transplants. Monitoring perfusion and oxygenation in transplanted organs in the 7 to 14 days period post-transplant can enhance graft and patient survival rates, and resultantly increase the availability of organs. In this work, we present in vitro results using a unique liver phantom that support the ability of our sensor to detect perfusion changes in the portal vein at low levels (50 mL/min . 4.5% of normal level). Our sensor measures diffuse reflection from three wavelengths (735, 805 and 940 nm) around the hemoglobin isobestic point (805 nm) to determine perfusion and oxygenation separately. To assess the sensitivity of our sensor to flow changes in the low range, we used two peristaltic pumps to pump a dye solution mimicking the optical properties of oxygenated blood, at various rates, through a PDMS based phantom mimicking the optical properties of liver tissue. The collected pulsatile signal increased by 120% (2.2X) for every 100 mL/min flow rise for all three wavelengths in the range 50 to 500 mL/min. In addition, we used different dye mixtures to mimic oxygenation changes at constant perfusion/flow levels. The optical properties of the dye mixtures mimic oxygen saturations ranging between 0 and 100%. The sensor was shown to be sensitive to changes in oxygen saturations above 50%.

  8. Polydimethylsiloxane Core-Polycaprolactone Shell Nanofibers as Biocompatible, Real-Time Oxygen Sensors

    PubMed Central

    Xue, Ruipeng; Behera, Prajna; Xu, Joshua; Viapiano, Mariano S.; Lannutti, John J.

    2014-01-01

    Real-time, continuous monitoring of local oxygen contents at the cellular level is desirable both for the study of cancer cell biology and in tissue engineering. In this paper, we report the successful fabrication of polydimethylsiloxane (PDMS) nanofibers containing oxygen-sensitive probes by electrospinning and the applications of these fibers as optical oxygen sensors for both gaseous and dissolved oxygen. A protective ‘shell’ layer of polycaprolactone (PCL) not only maintains the fiber morphology of PDMS during the slow curing process but also provides more biocompatible surfaces. Once this strategy was perfected, tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) (Ru(dpp)) and platinum octaethylporphyrin (PtOEP) were dissolved in the PDMS core and the resulting sensing performance established. These new core-shell sensors containing different sensitivity probes showed slight variations in oxygen response but all exhibited excellent Stern-Volmer linearity. Due in part to the porous nature of the fibers and the excellent oxygen permeability of PDMS, the new sensors show faster response (<0.5 s) −4–10 times faster than previous reports – than conventional 2D film-based oxygen sensors. Such core-shell fibers are readily integrated into standard cell culture plates or bioreactors. The photostability of these nanofiber-based sensors was also assessed. Culture of glioma cell lines (CNS1, U251) and glioma-derived primary cells (GBM34) revealed negligible differences in biological behavior suggesting that the presence of the porphyrin dyes within the core carries with it no strong cytotoxic effects. The unique combination of demonstrated biocompatibility due to the PCL ‘shell’ and the excellent oxygen transparency of the PDMS core makes this particular sensing platform promising for sensing in the context of biological environments. PMID:25006274

  9. Applications of quantum dots in optical fiber luminescent oxygen sensors

    NASA Astrophysics Data System (ADS)

    Jorge, Pedro A. S.; Mayeh, Mona; Benrashid, Ramazan; Caldas, Paulo; Santos, José L.; Farahi, Faramarz

    2006-06-01

    The potential applications of luminescent semiconductor nanocrystals to optical oxygen sensing are explored. The suitability of quantum dots to provide a reference signal in luminescence-based chemical sensors is addressed. A CdSe-ZnS nanocrystal, with an emission peak at 520 nm, is used to provide a reference signal. Measurements of oxygen concentration, which are based on the dynamic quenching of the luminescence of a ruthenium complex, are performed. Both the dye and the nanocrystal are immobilized in a solgel matrix and are excited by a blue LED. Experimental results show that the ratio between the reference and the sensor signals is highly insensitive to fluctuations of the excitation optical power. The use of CdTe, near-infrared quantum dots with an emission wavelength of 680 nm, in combination with a ruthenium complex to provide a new mechanism for oxygen sensing, is investigated. The possibility of creating oxygen sensitivity in different spectral regions is demonstrated. The results obtained clearly show that this technique can be applied to develop a wavelength division multiplexed system of oxygen sensors.

  10. Applications of quantum dots in optical fiber luminescent oxygen sensors.

    PubMed

    Jorge, Pedro A S; Mayeh, Mona; Benrashid, Ramazan; Caldas, Paulo; Santos, José L; Farahi, Faramarz

    2006-06-01

    The potential applications of luminescent semiconductor nanocrystals to optical oxygen sensing are explored. The suitability of quantum dots to provide a reference signal in luminescence-based chemical sensors is addressed. A CdSe-ZnS nanocrystal, with an emission peak at 520 nm, is used to provide a reference signal. Measurements of oxygen concentration, which are based on the dynamic quenching of the luminescence of a ruthenium complex, are performed. Both the dye and the nanocrystal are immobilized in a solgel matrix and are excited by a blue LED. Experimental results show that the ratio between the reference and the sensor signals is highly insensitive to fluctuations of the excitation optical power. The use of CdTe, near-infrared quantum dots with an emission wavelength of 680 nm, in combination with a ruthenium complex to provide a new mechanism for oxygen sensing, is investigated. The possibility of creating oxygen sensitivity in different spectral regions is demonstrated. The results obtained clearly show that this technique can be applied to develop a wavelength division multiplexed system of oxygen sensors. PMID:16724134

  11. Predicting Transitions in Oxygen Saturation Using Phone Sensors

    PubMed Central

    Cheng, Qian; Juen, Joshua; Hsu-Lumetta, Jennie

    2016-01-01

    Abstract Introduction: Widespread availability of mobile devices is revolutionizing health monitoring. Smartphones are ubiquitous, but it is unknown what vital signs can be monitored with medical quality. Oxygen saturation is a standard measure of health status. We have shown phone sensors can accurately measure walking patterns. Subjects and Methods: Twenty cardiopulmonary patients performed 6-min walk tests in pulmonary rehabilitation at a regional hospital. They wore pulse oximeters and carried smartphones running our MoveSense software, which continuously recorded saturation and motion. Continuous saturation defined categories corresponding to status levels, including transitions. Continuous motion was used to compute spatiotemporal gait parameters from sensor data. Our existing gait model was then trained with these data and used to predict transitions in oxygen saturation. For walking variation, 10-s windows are units for classifying into status categories. Results: Oxygen saturation clustered into three categories, corresponding to pulmonary function Global Initiative for Chronic Obstructive Lung Disease (GOLD) 1 and GOLD 2, with a Transition category where saturation varied around the mean rather than remaining steady with low standard deviation. This category indicates patients who are not clinically stable. The gait model predicted status during each measured window of free walking, with 100% accuracy for the 20 subjects, based on majority voting. Conclusions: Continuous recording of oxygen saturation can predict cardiopulmonary status, including patients in transition between status levels. Gait models using phone sensors can accurately predict these saturation categories from walking motion. This suggests medical devices for predicting clinical stability from passive monitoring using carried smartphones.

  12. Development and Performance of the Oxygen Sensor in the CSA-CP Aboard the International Space Station

    NASA Technical Reports Server (NTRS)

    Limero, Thomas; Beck, Steve; James, John T.

    2004-01-01

    A combustion products analyzer (CPA) was built for use on Shuttle in response to several thermodegradation incidents that had occurred during early flights. The CPA contained sensors that measured carbon monoxide, hydrogen chloride, hydrogen cyanide, and hydrogen fluoride. These marker compounds, monitored by the CPA, were selected based upon the likely products to be released in a spacecraft fire. When the Toxicology Laboratory group at Johnson Space Center (JSC) began to assess the air quality monitoring needs for the International Space Station (ISS), the CPA was the starting point for design of an instrument to monitor the atmosphere following a thermodegradation event. The final product was significantly different from the CPA and was named the compound specific analyzer-combustion products (CSA-CP). The major change from the CPA that will be the focus of this paper was the replacement of an unreliable hydrogen fluoride (HF) sensor with an oxygen sensor. A reliable HF sensor was not commercially available, but as the toxicology group reviewed the overall monitoring strategy for ISS, it appeared that a portable oxygen sensor to backup the major constituent analyzer was needed. Therefore, an oxygen sensor replaced the HF sensor in the new instrument. This paper will describe the development, deployment, and performance of the CSA-CP oxygen sensor on both Shuttle and ISS. Also, data for CSA-CP oxygen sensor accuracy at nominal and reduced pressures will be presented.

  13. Phosphorescent oxygen sensors based on nanostructured polyolefin substrates.

    PubMed

    Gillanders, Ross N; Arzhakova, Olga V; Hempel, Andreas; Dolgova, Alla; Kerry, Joe P; Yarysheva, Larisa M; Bakeev, Nikolai F; Volynskii, Alexander L; Papkovsky, Dmitri B

    2010-01-15

    New phosphorescent oxygen-sensitive materials based on nanostructured high density polyethylene and polypropylene films are described. The polymer substrates undergo treatment by a solvent crazing process to create a well-developed network of controlled, nanometer-size pores. Indicator dye molecules are then embedded by physical entrapment in such nanostructures which subsequently can be healed. Such sensors demonstrate improved working characteristics and allow simple, cost-efficient production and disposable use. They are well suited for large-scale applications such as nondestructive control of residual oxygen and "smart" packaging. PMID:20038091

  14. Oxygen sensor for monitoring gas mixtures containing hydrocarbons

    DOEpatents

    Ruka, Roswell J.; Basel, Richard A.

    1996-01-01

    A gas sensor measures O.sub.2 content of a reformable monitored gas containing hydrocarbons H.sub.2 O and/or CO.sub.2, preferably in association with an electrochemical power generation system. The gas sensor has a housing communicating with the monitored gas environment and carries the monitored gas through an integral catalytic hydrocarbon reforming chamber containing a reforming catalyst, and over a solid electrolyte electrochemical cell used for sensing purposes. The electrochemical cell includes a solid electrolyte between a sensor electrode that is exposed to the monitored gas, and a reference electrode that is isolated in the housing from the monitored gas and is exposed to a reference gas environment. A heating element is also provided in heat transfer communication with the gas sensor. A circuit that can include controls operable to adjust operations via valves or the like is connected between the sensor electrode and the reference electrode to process the electrical signal developed by the electrochemical cell. The electrical signal varies as a measure of the equilibrium oxygen partial pressure of the monitored gas. Signal noise is effectively reduced by maintaining a constant temperature in the area of the electrochemical cell and providing a monitored gas at chemical equilibria when contacting the electrochemical cell. The output gas from the electrochemical cell of the sensor is fed back into the conduits of the power generating system.

  15. Oxygen sensor for monitoring gas mixtures containing hydrocarbons

    DOEpatents

    Ruka, R.J.; Basel, R.A.

    1996-03-12

    A gas sensor measures O{sub 2} content of a reformable monitored gas containing hydrocarbons, H{sub 2}O and/or CO{sub 2}, preferably in association with an electrochemical power generation system. The gas sensor has a housing communicating with the monitored gas environment and carries the monitored gas through an integral catalytic hydrocarbon reforming chamber containing a reforming catalyst, and over a solid electrolyte electrochemical cell used for sensing purposes. The electrochemical cell includes a solid electrolyte between a sensor electrode that is exposed to the monitored gas, and a reference electrode that is isolated in the housing from the monitored gas and is exposed to a reference gas environment. A heating element is also provided in heat transfer communication with the gas sensor. A circuit that can include controls operable to adjust operations via valves or the like is connected between the sensor electrode and the reference electrode to process the electrical signal developed by the electrochemical cell. The electrical signal varies as a measure of the equilibrium oxygen partial pressure of the monitored gas. Signal noise is effectively reduced by maintaining a constant temperature in the area of the electrochemical cell and providing a monitored gas at chemical equilibria when contacting the electrochemical cell. The output gas from the electrochemical cell of the sensor is fed back into the conduits of the power generating system. 4 figs.

  16. Comparison of an oxygen concentrator and wall oxygen in the assessment of patients undergoing long term oxygen therapy assessment.

    PubMed

    Bolton, C E; Annandale, J A; Ebden, P

    2006-01-01

    Long term oxygen therapy (LTOT) is a recognised management option for hypoxaemic patients with chronic respiratory disease. Formal assessment is required which is usually conducted in the hospital and performed on piped oxygen to ensure correction of the hypoxaemia. However, an oxygen concentrator is the standard oxygen source for the patient at home who requires LTOT. The oxygen concentration delivered is lower from a concentrator than piped oxygen. Here, we present a study of ten hypoxaemic patients using both delivery sources in a cross-over design. The partial pressure of oxygen was lower in patients when receiving oxygen from a concentrator, p < 0.05. This encourages the Clinician to consider formal assessments on an oxygen concentrator in order to ensure that the hypoxaemia will be corrected when they are prescribed a concentrator for home use. PMID:16509177

  17. Contact CMOS imaging of gaseous oxygen sensor array

    PubMed Central

    Daivasagaya, Daisy S.; Yao, Lei; Yi Yung, Ka; Hajj-Hassan, Mohamad; Cheung, Maurice C.; Chodavarapu, Vamsy P.; Bright, Frank V.

    2014-01-01

    We describe a compact luminescent gaseous oxygen (O2) sensor microsystem based on the direct integration of sensor elements with a polymeric optical filter and placed on a low power complementary metal-oxide semiconductor (CMOS) imager integrated circuit (IC). The sensor operates on the measurement of excited-state emission intensity of O2-sensitive luminophore molecules tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) ([Ru(dpp)3]2+) encapsulated within sol–gel derived xerogel thin films. The polymeric optical filter is made with polydimethylsiloxane (PDMS) that is mixed with a dye (Sudan-II). The PDMS membrane surface is molded to incorporate arrays of trapezoidal microstructures that serve to focus the optical sensor signals on to the imager pixels. The molded PDMS membrane is then attached with the PDMS color filter. The xerogel sensor arrays are contact printed on top of the PDMS trapezoidal lens-like microstructures. The CMOS imager uses a 32 × 32 (1024 elements) array of active pixel sensors and each pixel includes a high-gain phototransistor to convert the detected optical signals into electrical currents. Correlated double sampling circuit, pixel address, digital control and signal integration circuits are also implemented on-chip. The CMOS imager data is read out as a serial coded signal. The CMOS imager consumes a static power of 320 µW and an average dynamic power of 625 µW when operating at 100 Hz sampling frequency and 1.8 V DC. This CMOS sensor system provides a useful platform for the development of miniaturized optical chemical gas sensors. PMID:24493909

  18. High-temperature potentiometric oxygen sensor with internal reference

    DOEpatents

    Routbort, Jules L.; Singh, Dileep; Dutta, Prabir K.; Ramasamy, Ramamoorthy; Spirig, John V.; Akbar, Sheikh

    2011-11-15

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

  19. Development of metalloporphyrin-derived interference-free oxygen sensors

    NASA Astrophysics Data System (ADS)

    Wu, Xuanzheng

    The main aim of this thesis is to develop novel highly sensitive, membrane-free, inexpensive one-way oxygen sensors that work in neutral solutions at or near 0 V vs. Ag/AgCl to avoid interference from oxidizing or reducing agents in water or blood samples. The theoretical background is to use chemically-modified electrodes with metalloporphyrins as catalysts for dioxygen reduction at or near 0 V vs. Ag/AgCl. Three approaches are employed to prepare metalloporphyrin-derived electrodes. 1. The first approach is based on a traditional chemical modification technique and commercial voltammetric electrodes. Iron(III)-tetra(3-methoxy-4-hydroxy-phenyl) porphyrin chloride (FeTMHPP) is dip-coated, dropwise-coated, and electrochemically-polymerized on four different bare electrodes: glassy carbon (GCE), graphite (GE), gold (AuE), and platinum electrodes (PtE), respectively. Their electrocatalytic properties for dioxygen reduction are characterized and compared. These chemically-modified electrodes demonstrate different electrocatalytic behavior for dioxygen reduction in PBS pH7.0. It is demonstrated for the first time that only eletrochemically polymerized poly-FeTMHPP film on bare PtE has a highly electrocatalytic property for dioxygen reduction in PBS pH7.0 with a cathode peak potential, Esb{pc}, ranging from 0 mV to +150 mV vs. Ag/AgCl which is controlled by the polymeric film thickness. The kinetic results show that this system has a four electron transfer mechanism for dioxygen reduction. The results are transferred to a thick film chip oxygen sensor. The poly-FeTMHPP/Pt chip oxygen sensor shows clearly that it has a potential to be a practical oxygen sensor. The dynamic range of the poly-FeTMHPP/Pt oxygen sensor between 50 and 350 muM covers the normal dissolved oxygen range of waste water and blood samples. The detection limit of 337 pM for dissolved oxygen in PBS pH7.0 allows a highly sensitive measurement. 2. In order to improve the stability of the sensor, we also

  20. An Optical Oxygen Sensor for Long-Term Continuous Monitoring of Dissolved Oxygen in Perfused Bioreactors

    NASA Technical Reports Server (NTRS)

    Gao, F. G.; Jeevarajan, A. S.; Anderson, M. M.

    2002-01-01

    For long-term growth of man1ITlalian cells in perfused bioreactors, it is essential to monitor the concentration of dissolved oxygen (DO) present in the culture medium to quantitate and control level of DO. Continuous measurement of the amount of DO in the cell culture medium in-line under sterile conditions in NASA's perfused bioreactor requires that the oxygen sensor provide increased sensitivity and be sterilizable and nontoxic. Additionally, long-term cell culture experiments require that the calibration be maintained several weeks or months. Although there are a number of sensors for dissolved oxygen on the market and under development elsewhere, very few meet these stringent conditions. An optical oxygen sensor (BOXY) based on dynamic fluorescent quenching and a pulsed blue LED light source was developed in our laboratory to address these requirements. Tris( 4,7 -diphenyl-l, 1 O-phenanthroline )ruthenium(II) chloride is employed as the fluorescent dye indicator. The sensing element consists of a glass capillary (OD 4.0 mm; ID 2.0 mm) coated internally with a thin layer of the fluorescent dye in silicone matrix and overlayed with a black shielding layer. Irradiation of the sensing element with blue light (blue LED with emission maximum at 475 nm) generates a red fluorescence centered at 626 nm. The fluorescence intensity is correlated to the concentration of DO present in the culture medium, following the modified non-linear Stern-Volmer equation. By using a pulsed irradiating light source, the problem of dye-bleaching, which is often encountered in long-term continuous measurements of tIns type, 'is minimized. To date we achieved sensor resolution of 0.3 mmHg at 50 mmHg p02, and 0.6 mmHg at 100 mmHg p02, with a response time of about one minute. Calibration was accomplished in sterile phosphate-buffered saline with a blood-gas analyzer (BGA) measurement as reference. Stand-alone software was also developed to control the sensor and bioreactor as well as to

  1. Using pulse oximetry to assess oxygen levels.

    PubMed

    Olive, Sandra

    Abstract Olive S (2016) Using pulse oximetry to assess oxygen levels. Detecting low oxygen levels in patients is important but not always easy; central cyanosis--when a patient's lips, tongue and mucus membranes acquire a blue tinge--can be missed, even by skilled observers, until significant hypoxaemia is present. Pulse oximetry can be undertaken to measure a patient's oxygen levels and help identify earlier when action must be taken. This article outlines the procedure and its limitations, as well as the circumstances in which it should be used. PMID:27295798

  2. Oxygen saturation in free-diving whales: optical sensor development

    NASA Astrophysics Data System (ADS)

    Gutierrez-Herrera, Enoch; Vacas-Jacques, Paulino; Anderson, Rox; Zapol, Warren; Franco, Walfre

    2013-02-01

    Mass stranding of live whales has been explained by proposing many natural or human-related causes. Recent necropsy reports suggest a link between the mass stranding of beaked whales and the use of naval mid-frequency sonar. Surprisingly, whales have experienced symptoms similar to those caused by inert gas bubbles in human divers. Our goal is to develop a compact optical sensor to monitor the consumption of the oxygen stores in the muscle of freely diving whales. To this end we have proposed the use of a near-infrared phase-modulated frequency-domain spectrophotometer, in reflectance mode, to probe tissue oxygenation. Our probe consists of three main components: radiofrequency (RF) modulated light sources, a high-bandwidth avalanche photodiode with transimpedance amplifier, and a RF gain and phase detector. In this work, we concentrate on the design and performance of the light sensor, and its corresponding amplifier unit. We compare three state-of-the-art avalanche photodiodes: one through-hole device and two surface-mount detectors. We demonstrate that the gain due to the avalanche effect differs between sensors. The avalanche gain near maximum bias of the through-hole device exceeds by a factor of 2.5 and 8.3 that of the surface-mount detectors. We present the behavior of our assembled through-hole detector plus high-bandwidth transimpedance amplifier, and compare its performance to that of a commercially available module. The assembled unit enables variable gain, its phase noise is qualitatively lower, and the form factor is significantly smaller. Having a detecting unit that is compact, flexible, and functional is a milestone in the development of our tissue oxygenation tag.

  3. Field comparison of optical and clark cell dissolved-oxygen sensors

    USGS Publications Warehouse

    Fulford, J.M.; Davies, W.J.; Garcia, L.

    2005-01-01

    Three multi-parameter water-quality monitors equipped with either Clark cell type or optical type dissolved-oxygen sensors were deployed for 30 days in a brackish (salinity <10 parts per thousand) environment to determine the sensitivity of the sensors to biofouling. The dissolved-oxygen sensors compared periodically to a hand-held dissolved oxygen sensor, but were not serviced or cleaned during the deployment. One of the Clark cell sensors and the optical sensor performed similarly during the deployment. The remaining Clark cell sensor was not aged correctly prior to deployment and did not perform as well as the other sensors. All sensors experienced substantial biofouling that gradually degraded the accuracy of the dissolved-oxygen measurement during the last half of the deployment period. Copyright ASCE 2005.

  4. High-temperature oxygen sensors for glass-forming melts.

    PubMed

    Baucke, F G

    1996-09-01

    Electrochemical sensors are reported for the on-line measurement of oxygen partial pressures of oxidic glass-forming melts on a laboratory and technical scale. Based on the principle of solid electrolyte cells without transference, they are principally simple units. The extreme chemical and temperature conditions of their applications, however, demanded extensive fundamental investigations and resulted in specific forms of reference and measuring electrodes, a thermo-dynamic procedure of verifying the correct functioning of such cells, and a method of measuring thermoelectric voltages of non-isothermal glass melts. PMID:15048355

  5. A new generation of high temperature oxygen sensors

    NASA Astrophysics Data System (ADS)

    Spirig, John V.

    Potentiometric internal reference oxygen sensors were created by embedding a metal/metal oxide mixture within an yttria-stabilized zirconia oxygen-conducting ceramic superstructure. A static internal reference oxygen pressure was produced inside the reference chamber of the sensor at the target application temperature. The metal/metal oxide-containing reference chamber was sealed within the stabilized zirconia ceramic superstructure by a high pressure (3-6 MPa) and high temperature (1200-1300°C) bonding method that initiated grain boundary sliding between the ceramic components. The bonding method created ceramic joints that were pore-free and indistinguishable from the bulk ceramic. The oxygen sensor presented in this study is capable of long-term operation and is resistant to the strains of thermal cycling. The temperature ceiling of this device was limited to 800°C by the glass used to seal the sensor package where the lead wire breached the inner-to-outer environment. Were it possible to create a gas-tight joint between an electron carrier and stabilized zirconia, additional sealing agents would not be necessary during sensor construction. In order to enable this enhancement it is necessary to make a gas-tight joint between two dissimilar materials: a ceramic electrolyte and an efficient ceramic electron carrier. Aluminum-doped lanthanum strontium manganese oxide, La0.77Sr 0.20Al0.9Mn0.1O3, was joined to stabilized tetragonal zirconia polymorph YTZP (ZrO2)0.97(Y 2O3)0.03 by a uniaxial stress (3-6 MPa) and high-temperature (1250-1350°C) bonding method that initiated grain-boundary sliding between the ceramic components. An analysis of reactivity between different Al-dopings of LaxSr1-xAlyMn1-yO3 indicated that the Al:Mn ratio must be high to diminish the reaction between LaxSr1-xAlyMn1-yO3 and stabilized zirconia. While the resulting compound, La0.77Sr 0.20Al0.9Mn0.1O3, was an inefficient electron carrier, the successful bond between an aluminum

  6. Optimizing probe design for an implantable perfusion and oxygenation sensor

    SciTech Connect

    Akl, Tony; Long, Ruiqi; McShane, Michael J.; Ericson, Milton Nance; Wilson, Mark A.; Cote, Gerard L.

    2011-01-01

    In an effort to develop an implantable optical perfusion and oxygenation sensor, based on multiwavelength reflectance pulse oximetry, we investigate the effect of source detector separation and other source-detector characteristics to optimize the sensor s signal to background ratio using Monte Carlo (MC) based simulations and in vitro phantom studies. Separations in the range 0.45 to 1.25 mm were found to be optimal in the case of a point source. The numerical aperture (NA) of the source had no effect on the collected signal while the widening of the source spatial profile caused a shift in the optimal source-detector separation. Specifically, for a 4.5 mm flat beam and a 2.4 mm 2.5 mm photodetector, the optimal performance was found to be when the source and detector are adjacent to each other. These modeling results were confirmed by data collected from in vitro experiments on a liver phantom perfused with dye solutions mimicking the absorption properties of hemoglobin for different oxygenation states.

  7. Measurement of atomic oxygen in the middle atmosphere using solid electrolyte sensors and catalytic probes

    NASA Astrophysics Data System (ADS)

    Eberhart, M.; Löhle, S.; Steinbeck, A.; Binder, T.; Fasoulas, S.

    2015-09-01

    The middle- and upper-atmospheric energy budget is largely dominated by reactions involving atomic oxygen (O). Modeling of these processes requires detailed knowledge about the distribution of this oxygen species. Understanding the mutual contributions of atomic oxygen and wave motions to the atmospheric heating is the main goal of the rocket project WADIS (WAve propagation and DISsipation in the middle atmosphere). It includes, amongst others, our instruments for the measurement of atomic oxygen that have both been developed with the aim of resolving density variations on small vertical scales along the trajectory. In this paper the instrument based on catalytic effects (PHLUX: Pyrometric Heat Flux Experiment) is introduced briefly. The experiment employing solid electrolyte sensors (FIPEX: Flux φ(Phi) Probe Experiment) is presented in detail. These sensors were laboratory calibrated using a microwave plasma as a source of atomic oxygen in combination with mass spectrometer reference measurements. The spectrometer was in turn calibrated for O with a method based on methane. In order to get insight into the horizontal variability, the rocket payload had instrument decks at both ends. Each housed several sensor heads measuring during both the up- and downleg of the trajectory. The WADIS project comprises two rocket flights during different geophysical conditions. Results from WADIS-1 are presented, which was successfully launched in June 2013 from the Andøya Space Center, Norway. FIPEX data were sampled at 100 Hz and yield atomic oxygen density profiles with a vertical resolution better than 9 m. This allows density variations to be studied on very small spatial scales. Numerical simulations of the flow field around the rocket were done at several points of the trajectory to assess the influence of aerodynamic effects on the measurement results. Density profiles peak at 3 × 1010 cm-3 at altitudes of 93.6 and 96 km for the up- and downleg, respectively.

  8. Measurement of atomic oxygen in the middle atmosphere using solid electrolyte sensors and catalytic probes

    NASA Astrophysics Data System (ADS)

    Eberhart, M.; Löhle, S.; Steinbeck, A.; Binder, T.; Fasoulas, S.

    2015-03-01

    The atmospheric energy budget is largely dominated by reactions involving atomic oxygen (O). Modeling of these processes requires detailed knowledge about the distribution of this oxygen species. Understanding the mutual contributions of atomic oxygen and wave motions to the atmospheric heating is the main goal of the rocket campaign WADIS. It includes, amongst others, two of our instruments for the measurement of atomic oxygen that have both been developed with the aim of resolving density variations on small vertical scales along the trajectory. In this paper the instrument based on catalytic effects (PHLUX) is introduced briefly. The experiment employing solid electrolyte sensors (FIPEX) is presented in detail. These sensors were laboratory calibrated using a microwave plasma as a source for atomic oxygen in combination with mass spectrometer reference measurements. The spectrometer was in turn calibrated for O with a method based on methane. In order to get insight into the horizontal variability the rocket payload had instrument decks at both ends. Each housed several sensor heads measuring during both the up- and downleg of the trajectory. The WADIS campaign comprises two rocket flights during different geophysical conditions. Results from WADIS-1 are presented which was successfully launched in June 2013 from Andøya Rocket Range, Norway. FIPEX data was sampled with 100 Hz and yield atomic oxygen density profiles with a vertical resolution better than 10 m. Numerical simulations of the flow field around the rocket were done at several points of the trajectory to assess the influence of aerodynamic effects on the measurement results. Density profiles peak at 3 × 1010 cm-3 at altitudes of 93.6 and 96 km for up- and downleg respectively.

  9. Active sensor assessment of corn nitrogen status

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Use of active sensor measurements of in-season corn (Zea mays L.) nitrogen (N) status for directing spatially-variable N applications has been advocated to improve N use efficiency. However, first it is necessary to confirm that active sensors can reliably assess corn N status. Our research goals we...

  10. Oxygen Compatibility Assessment of Components and Systems

    NASA Technical Reports Server (NTRS)

    Stoltzfus, Joel; Sparks, Kyle

    2010-01-01

    Fire hazards are inherent in oxygen systems and a storied history of fires in rocket engine propulsion components exists. To detect and mitigate these fire hazards requires careful, detailed, and thorough analyses applied during the design process. The oxygen compatibility assessment (OCA) process designed by NASA Johnson Space Center (JSC) White Sands Test Facility (WSTF) can be used to determine the presence of fire hazards in oxygen systems and the likelihood of a fire. This process may be used as both a design guide and during the approval process to ensure proper design features and material selection. The procedure for performing an OCA is a structured step-by-step process to determine the most severe operating conditions; assess the flammability of the system materials at the use conditions; evaluate the presence and efficacy of ignition mechanisms; assess the potential for a fire to breach the system; and determine the reaction effect (the potential loss of life, mission, and system functionality as the result of a fire). This process should be performed for each component in a system. The results of each component assessment, and the overall system assessment, should be recorded in a report that can be used in the short term to communicate hazards and their mitigation and to aid in system/component development and, in the long term, to solve anomalies that occur during engine testing and operation.

  11. Ultra-sensitive optical oxygen sensors for characterisation of nearly anoxic systems

    PubMed Central

    Lehner, Philipp; Staudinger, Christoph; Borisov, Sergey M.; Klimant, Ingo

    2014-01-01

    Oxygen quantification in trace amounts is essential in many fields of science and technology. Optical oxygen sensors proved invaluable tools for oxygen measurements in a broad concentration range but until now neither optical nor electrochemical oxygen sensors were able to quantify oxygen in the sub-nanomolar concentration range. Herein we present new optical oxygen sensing materials with unmatched sensitivity. They rely on the combination of ultra-long decaying (several hundred milliseconds lifetime) phosphorescent boron- and aluminium-chelates and highly oxygen-permeable and chemically stable perfluorinated polymers. The sensitivity of the new sensors is improved up to 20-fold compared to state-of-the-art analogues. The limits of detection are as low as 5 parts per billion, volume in gas phase under atmospheric pressure or 7 picomolar in solution. The sensors enable completely new applications for monitoring of oxygen in previously inaccessible concentration ranges. PMID:25042041

  12. Ultra-sensitive optical oxygen sensors for characterization of nearly anoxic systems.

    PubMed

    Lehner, Philipp; Staudinger, Christoph; Borisov, Sergey M; Klimant, Ingo

    2014-01-01

    Oxygen quantification in trace amounts is essential in many fields of science and technology. Optical oxygen sensors proved invaluable tools for oxygen measurements in a broad concentration range, but until now neither optical nor electrochemical oxygen sensors were able to quantify oxygen in the sub-nanomolar concentration range. Herein we present new optical oxygen-sensing materials with unmatched sensitivity. They rely on the combination of ultra-long decaying (several 100 ms lifetime) phosphorescent boron- and aluminium-chelates, and highly oxygen-permeable and chemically stable perfluorinated polymers. The sensitivity of the new sensors is improved up to 20-fold compared with state-of-the-art analogues. The limits of detection are as low as 5 p.p.b., volume in gas phase under atmospheric pressure or 7 pM in solution. The sensors enable completely new applications for monitoring of oxygen in previously inaccessible concentration ranges. PMID:25042041

  13. Assessments for oxygen therapy in COPD: are we under correcting arterial oxygen tensions?

    PubMed

    Dheda, K; Lim, K; Ollivere, B; Leftley, J; Lampe, F C; Salisbury, A; Dilworth, J P; Rajakulasingam, R K; Rajakulasingum, R K

    2004-12-01

    There is little data about the use of different oxygen sources during assessment for long-term oxygen therapy (LTOT) and how this impacts upon blood oxygen tensions and prescribed flow rates. Patients with chronic obstructive pulmonary disease (COPD), n=30, had assessments for LTOT using both an oxygen-concentrator and piped hospital oxygen (wall-oxygen) as supply sources. In addition, a random survey of 64 hospitals was conducted to determine what source of oxygen supply was used during assessments. Wall-oxygen was used by 89% of hospitals to perform assessments. During assessments, the median oxygen flow required to achieve an arterial oxygen tension (Pa,O2) >8 kPa was significantly greater for an oxygen-concentrator than for wall-oxygen, with a median difference (range) in flow of 1 (0-3) L. This difference was most likely in those with an forced expiratory volume <30% of predicted. At an oxygen flow of 1 L.min(-1), the mean P(a,O2) using an oxygen-concentrator was significantly lower than that of the wall-oxygen value, with a difference of 1.32+/-1.19 kPa (mean+/-SD). The common practice of using wall-oxygen to perform assessments significantly underestimates the required oxygen-concentrator flow rate. This may have implications for the long-term effect of domiciliary oxygen therapy. PMID:15572538

  14. Unattended ground sensor situation assessment workstation

    NASA Astrophysics Data System (ADS)

    Jeppesen, David M.; Trellue, Ron

    1997-07-01

    Advancements in both sensor hardware technology and in software systems and processing technology have enabled the development of practical realtime situation assessment capabilities based upon information from unattended ground sensors. A decision support workstation that employs rule- based expert system processing of reports from unattended ground sensors is described. The primary goal of this development activity is to produce a suite of software to track vehicles using data from unattended ground sensors. The situational assessment products from this system have stand-alone utility, but are also intended to provide cueing support for overhead sensors and supplementary feeds to all- source fusion centers. The conceptual framework, developmental architecture, and demonstration field tests of the system are described.

  15. Unattended ground sensor situation assessment workstation

    SciTech Connect

    Jeppesen, D.; Trellue, R.

    1997-04-01

    Effective utilization of unattended ground sensors (UGSs) in a theater reconnaissance, surveillance, target acquisition, and kill assessment environment requires that a human operator be able to interpret, and collectively assess, the significance of real time data obtained from UGS emplacements over large geographical regions of interest. The products of this UGS data interpretation and assessment activity can then be used in the decision support process for command level evaluation of appropriate courses of action. Advancements in both sensor hardware technology and in software systems and processing technology have enabled the development of practical real time situation assessment capabilities based upon information from unattended ground sensors. A decision support workstation that employs rule-based expert system processing of reports from unattended ground sensors is described. The primary goal of this development activity is to produce a suite of software to track vehicles using data from unattended ground sensors. The situational assessment products from this system have stand-alone utility, but are also intended to provide cueing support for overhead sensors and supplementary feeds to all-source fusion centers. The conceptual framework, developmental architecture, and demonstration field tests of the system are described.

  16. Physico-Mathematical Simulation of a Homogeneous Thermal Field of Multichannel Raster Matrixes for Sensors of Oxygen

    PubMed Central

    Kotovskyi, Vitalij; Dzhezherya, Yurii; Dovzhenko, Aleksandr; Višniakov, Nikolaj; Šešok, Andžela

    2015-01-01

    In the paper, an opportunity for the development of multichannel transcutaneous raster matrixes for sensors of oxygen on the basis of an electrochemical cell sensor is described. An analysis of the influence of heat sources on the distribution of the temperature pattern of a raster matrix for sensors of oxygen had been carried out, and their optimum configuration had been found. The application of such matrixes will enable one to obtain information about the distribution of the partial pressure of oxygen from the skin cover of the object of research in dynamics, to assess its functional health pattern in a more comprehensive way and to control the effect of possible remedial actions. PMID:25591170

  17. Physico-mathematical simulation of a homogeneous thermal field of multichannel raster matrixes for sensors of oxygen.

    PubMed

    Kotovskyi, Vitalij; Dzhezherya, Yurii; Dovzhenko, Aleksandr; Višniakov, Nikolaj; Šešok, Andžela

    2015-01-01

    In the paper, an opportunity for the development of multichannel transcutaneous raster matrixes for sensors of oxygen on the basis of an electrochemical cell sensor is described. An analysis of the influence of heat sources on the distribution of the temperature pattern of a raster matrix for sensors of oxygen had been carried out, and their optimum configuration had been found. The application of such matrixes will enable one to obtain information about the distribution of the partial pressure of oxygen from the skin cover of the object of research in dynamics, to assess its functional health pattern in a more comprehensive way and to control the effect of possible remedial actions. PMID:25591170

  18. Material condition assessment with eddy current sensors

    NASA Technical Reports Server (NTRS)

    Goldfine, Neil J. (Inventor); Washabaugh, Andrew P. (Inventor); Sheiretov, Yanko K. (Inventor); Schlicker, Darrell E. (Inventor); Lyons, Robert J. (Inventor); Windoloski, Mark D. (Inventor); Craven, Christopher A. (Inventor); Tsukernik, Vladimir B. (Inventor); Grundy, David C. (Inventor)

    2010-01-01

    Eddy current sensors and sensor arrays are used for process quality and material condition assessment of conducting materials. In an embodiment, changes in spatially registered high resolution images taken before and after cold work processing reflect the quality of the process, such as intensity and coverage. These images also permit the suppression or removal of local outlier variations. Anisotropy in a material property, such as magnetic permeability or electrical conductivity, can be intentionally introduced and used to assess material condition resulting from an operation, such as a cold work or heat treatment. The anisotropy is determined by sensors that provide directional property measurements. The sensor directionality arises from constructs that use a linear conducting drive segment to impose the magnetic field in a test material. Maintaining the orientation of this drive segment, and associated sense elements, relative to a material edge provides enhanced sensitivity for crack detection at edges.

  19. High Throughput Micropatterning of Optical Oxygen Sensor for Single Cell Analysis

    PubMed Central

    Zhu, Haixin; Tian, Yanqing; Bhushan, Shivani; Su, Fengyu; Meldrum, Deirdre R.

    2012-01-01

    In this paper, we present our results from process development and characterization of optical oxygen sensors that are patterned by traditional UV lithography. An oxygen sensitive luminescent probe, platinum octaethylporphyrin (PtOEP), was encapsulated in commercially purchased photoresist (AZ5214) to form uniform thin sensor films on fused silica substrates. Plasticizer ethoxylated trimethylolpropane triacrylate (SR454) was added to the dye-photoresist sensor mixtures to improve the oxygen sensitivity. The optimum sensor mixture composition that can be patterned with maximum sensitivity was identified. The microfabrication process conditions, cell adherence and oxygen sensitivity results from patterned structures were characterized in detail. Down to 3 µm features have been fabricated on fused silica substrates using the developed techniques. The result implies the developed methods can provide a feasible way to miniaturize the optical sensor system for single cell analysis with precise control of sensor volume and response PMID:23066352

  20. Dual fluorescence sensor for trace oxygen and temperature with unmatched range and sensitivity.

    PubMed

    Baleizão, Carlos; Nagl, Stefan; Schäferling, Michael; Berberan-Santos, Mário N; Wolfbeis, Otto S

    2008-08-15

    An optical dual sensor for oxygen and temperature is presented that is highly oxygen sensitive and covers a broad temperature range. Dual sensing is based on luminescence lifetime measurements. The novel sensor contains two luminescent compounds incorporated into polymer films. The temperature-sensitive dye (ruthenium tris-1,10-phenanthroline) has a highly temperature-dependent luminescence and is incorporated in poly(acrylonitrile) to avoid cross-sensitivity to oxygen. Fullerene C70 was used as the oxygen-sensitive probe owing to its strong thermally activated delayed fluorescence at elevated temperatures that is extremely oxygen sensitive. The cross-sensitivity of C70 to temperature is accounted for by means of the temperature sensor. C70 is incorporated into a highly oxygen-permeable polymer, either ethyl cellulose or organosilica. The two luminescent probes have different emission spectra and decay times, and their emissions can be discriminated using both parameters. Spatially resolved sensing is achieved by means of fluorescence lifetime imaging. The response times of the sensor to oxygen are short. The dual sensor exhibits a temperature operation range between at least 0 and 120 degrees C, and detection limits for oxygen in the ppbv range, operating for oxygen concentrations up to at least 50 ppmv. These ranges outperform all dual oxygen and temperature sensors reported so far. The dual sensor presented in this study is especially appropriate for measurements under extreme conditions such as high temperatures and ultralow oxygen levels. This dual sensor is a key step forward in a number of scientifically or commercially important applications including food packaging, for monitoring of hyperthermophilic microorganisms, in space technology, and safety and security applications in terms of detection of oxygen leaks. PMID:18651755

  1. Advances towards the qualification of an aircraft fuel tank inert environment fiber optic oxygen sensor system

    NASA Astrophysics Data System (ADS)

    Mendoza, Edgar A.; Esterkin, Yan; Kempen, Cornelia; Sun, Songjian; Susko, Kenneth; Goglia, John

    2011-06-01

    An all optical pressure and temperature compensated fiber optic oxygen sensor (FOxSenseTM) system is under qualification for use in the in-situ closed-loop-control of the inert atmosphere environment inside fuel tanks of military and commercial aircraft. The all-optical oxygen environment control sensor is a passive, intrinsically safe, fiber-optic sensor device with no electrical connections leading to the sensors installed within the fuel tanks of an aircraft. To control the fuel tank environment, an array of multiple sensors is deployed throughout the fuel tanks of an aircraft, and a remote multi-channel optoelectronic system is used to monitor the status of all the sensors in real time to provide feedback oxygen environment information to the on-board inert gas generating system (OBIGS). Qualification testing of the all optical sensor have demonstrated the ability to monitor the oxygen environment inside a simulated fuel tank environment in the oxygen range from 0% to 21% oxygen concentrations, temperatures from (-) 40°C to (+) 60°C, and altitudes from sea level to 40,000 feet. Fiber optic oxygen sensors with built-in temperature compensation as well as the conduit fiber optic cables have passed DO-160E including acoustic noise and burn test.

  2. Methods and Best Practice to Intercompare Dissolved Oxygen Sensors and Fluorometers/Turbidimeters for Oceanographic Applications

    PubMed Central

    Pensieri, Sara; Bozzano, Roberto; Schiano, M. Elisabetta; Ntoumas, Manolis; Potiris, Emmanouil; Frangoulis, Constantin; Podaras, Dimitrios; Petihakis, George

    2016-01-01

    In European seas, ocean monitoring strategies in terms of key parameters, space and time scale vary widely for a range of technical and economic reasons. Nonetheless, the growing interest in the ocean interior promotes the investigation of processes such as oxygen consumption, primary productivity and ocean acidity requiring that close attention is paid to the instruments in terms of measurement setup, configuration, calibration, maintenance procedures and quality assessment. To this aim, two separate hardware and software tools were developed in order to test and simultaneously intercompare several oxygen probes and fluorometers/turbidimeters, respectively in the same environmental conditions, with a configuration as close as possible to real in-situ deployment. The chamber designed to perform chlorophyll-a and turbidity tests allowed for the simultaneous acquisition of analogue and digital signals of several sensors at the same time, so it was sufficiently compact to be used in both laboratory and onboard vessels. Methodologies and best practice committed to the intercomparison of dissolved oxygen sensors and fluorometers/turbidimeters have been used, which aid in the promotion of interoperability to access key infrastructures, such as ocean observatories and calibration facilities. Results from laboratory tests as well as field tests in the Mediterranean Sea are presented. PMID:27196908

  3. Methods and Best Practice to Intercompare Dissolved Oxygen Sensors and Fluorometers/Turbidimeters for Oceanographic Applications.

    PubMed

    Pensieri, Sara; Bozzano, Roberto; Schiano, M Elisabetta; Ntoumas, Manolis; Potiris, Emmanouil; Frangoulis, Constantin; Podaras, Dimitrios; Petihakis, George

    2016-01-01

    In European seas, ocean monitoring strategies in terms of key parameters, space and time scale vary widely for a range of technical and economic reasons. Nonetheless, the growing interest in the ocean interior promotes the investigation of processes such as oxygen consumption, primary productivity and ocean acidity requiring that close attention is paid to the instruments in terms of measurement setup, configuration, calibration, maintenance procedures and quality assessment. To this aim, two separate hardware and software tools were developed in order to test and simultaneously intercompare several oxygen probes and fluorometers/turbidimeters, respectively in the same environmental conditions, with a configuration as close as possible to real in-situ deployment. The chamber designed to perform chlorophyll-a and turbidity tests allowed for the simultaneous acquisition of analogue and digital signals of several sensors at the same time, so it was sufficiently compact to be used in both laboratory and onboard vessels. Methodologies and best practice committed to the intercomparison of dissolved oxygen sensors and fluorometers/turbidimeters have been used, which aid in the promotion of interoperability to access key infrastructures, such as ocean observatories and calibration facilities. Results from laboratory tests as well as field tests in the Mediterranean Sea are presented. PMID:27196908

  4. Optical triple sensor for measuring pH, oxygen, and carbon dioxide in bioreactors

    NASA Astrophysics Data System (ADS)

    Weigl, Bernhard H.; Holobar, Andrej; Trettnak, Wolfgang; Klimant, Ingo; Kraus, H.; O'Leary, Paul; Wolfbeis, Otto S.

    1993-04-01

    A triple sensor unit consisting of opto-chemical sensors for measurement of pH, oxygen, and carbon dioxide is presented. The pH sensor and the CO2 sensor are based on the color change of a pH-sensitive dye immobilized on a polymeric support. The resulting changes in absorption are monitored through optical fibers at one or two analytical wavelengths. The oxygen sensor is based on the quenching of the fluorescence of a metalorganic dye. The operation principle and the performance of all three sensors are described thoroughly with respect to their application in bioreactors. All three sensors are fully LED compatible. The chemical and mechanical stability, especially against common sterilization methods, are described in some detail. A calibration and measurement software comprising fit routines for the sensors and a mathematical treatment of the results are presented as well.

  5. Sensor based soil health assessment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Quantification and assessment of soil health involves determining how well a soil is performing its biological, chemical, and physical functions relative to its inherent potential. Due to high cost, labor requirements, and soil disturbance, traditional laboratory analyses cannot provide high resolut...

  6. Subpicosecond oxygen trapping in the heme pocket of the oxygen sensor FixL observed by time-resolved resonance Raman spectroscopy.

    PubMed

    Kruglik, Sergei G; Jasaitis, Audrius; Hola, Klara; Yamashita, Taku; Liebl, Ursula; Martin, Jean-Louis; Vos, Marten H

    2007-05-01

    Dissociation of oxygen from the heme domain of the bacterial oxygen sensor protein FixL constitutes the first step in hypoxia-induced signaling. In the present study, the photodissociation of the heme-O2 bond was used to synchronize this event, and time-resolved resonance Raman (TR(3)) spectroscopy with subpicosecond time resolution was implemented to characterize the heme configuration of the primary photoproduct. TR(3) measurements on heme-oxycomplexes are highly challenging and have not yet been reported. Whereas in all other known six-coordinated heme protein complexes with diatomic ligands, including the oxymyoglobin reported here, heme iron out-of-plane motion (doming) occurs faster than 1 ps after iron-ligand bond breaking; surprisingly, no sizeable doming is observed in the oxycomplex of the Bradyrhizobium japonicum FixL sensor domain (FixLH). This assessment is deduced from the absence of the iron-histidine band around 217 cm(-1) as early as 0.5 ps. We suggest that efficient ultrafast oxygen rebinding to the heme occurs on the femtosecond time scale, thus hindering heme doming. Comparing WT oxy-FixLH, mutant proteins FixLH-R220H and FixLH-R220Q, the respective carbonmonoxy-complexes, and oxymyoglobin, we show that a hydrogen bond of the terminal oxygen atom with the residue in position 220 is responsible for the observed behavior; in WT FixL this residue is arginine, crucially implicated in signal transmission. We propose that the rigid O2 configuration imposed by this residue, in combination with the hydrophobic and constrained properties of the distal cavity, keep dissociated oxygen in place. These results uncover the origin of the "oxygen cage" properties of this oxygen sensor protein. PMID:17446273

  7. Miniature dissolved oxygen and turbulence optical sensor for river and coastal environmental applications

    NASA Astrophysics Data System (ADS)

    Carapezza, Edward M.; Lombardi, Gabrial; Butman, Jerry; Babb, Ivar

    2009-09-01

    This paper describes an innovative miniature optical sensor for predicting dissolved oxygen concentrations and measuring turbulence in river and littoral water columns. The dissolved oxygen and turbulence sensor consists of a single-frequency laser transmitter and a photodetector on which the scattered light from the turbulent water at the base of a dam or spillway is coherently mixed with a sample of the transmitted beam. This miniature sensor could be used both upstream and downsteam of dams and weirs to predict the amount of dissolved oxygen and turbulence in these waters. It could also be used on mobile platforms, such as unmanned underwater vehicles (UUV's), to monitor the edges of biological or chemical plumes or for wake follow platforms, schools of fish or marine mammals or on stationary unattended underwater sensors to monitor natural aeration and turbulence in littoral and riverine waters. Arrays of fixed unattended sensors could be used to detect the wake of transiting submerged vehicles, scuba divers, marine mammals or large schools of fish. A mobile platform equipped with a miniature sensor could to be cued to the general location and depth of an underwater target and then the platform could use this small aperture sensor to acquire and follow the wake. This dissolved oxygen and turbulence sensor system could be miniaturized and packaged into a very small volume; approximately the size of a wristwatch.

  8. Variability of Transcutaneous Oxygen and Carbon Dioxide Pressure Measurements Associated with Sensor Location.

    PubMed

    Górska, K; Korczyński, P; Maskey-Warzęchowska, M; Chazan, R; Krenke, R

    2015-01-01

    Transcutaneous measurement of oxygen and carbon dioxide pressure (PtcO2 and PtcCO2) is useful in gas exchange monitoring. However, the relationship between PtcO2, pulse oximetry (SaO2) and arterial blood gases (ABG) is unclear. The aim of the present study was to compare PtcO2 and PtcCO2 with SaO2 and ABG, to evaluate the effect of sensor location on the results and stability of PtcO2 and PtcCO2, and to assess the impact of body composition on PtcO2 and PtcCO2. PtcO2 and PtcCO2 were measured in 20 healthy volunteers at three locations: right second intercostal space, lateral surface of the abdomen, and the inner surface of the left arm. The results were recorded 10, 15, and 20 min after sensor fixation and compared with SaO2 and ABG measured 20 min after electrode placement on the chest. Body composition was evaluated by bioimpedance. The findings were that PtcO2 was stable on the chest; but on the arm and abdomen it increased and reached maximum at 20 min. Transcutaneous PCO2 stabilized at 10 min in all the three locations. No significant correlations between PtcO2 and SaO2 or PaO2 were found. Transcutaneous PCO2 correlated with PaCO2. Both PtcO2 and PtcCO2 were not influenced by body composition. We conclude that the value of PtcO2 in monitoring of blood oxygenation was not unequivocally confirmed; PtcCO2 reliably reflects PaCO2, irrespective of sensor location. Body composition does not affect PtcO2 and PtcCO2. PMID:25820668

  9. Estimating IC engine exhaust gas lambda and oxygen from the response of a universal exhaust gas oxygen sensor

    NASA Astrophysics Data System (ADS)

    Collings, N.; Harris, J. A.; Glover, K.

    2013-09-01

    Universal exhaust gas oxygen sensors (UEGOs) are in widespread use in internal combustion engines where they are used to measure lambda (the non-dimensional air-fuel ratio) and oxygen concentration (X_{O_2 }). The sensors are used on production engines and for research and development. In a previous paper, a model of the UEGO sensor was presented, based on a solution of the Stefan-Maxwell equations for an axisymmetric geometry, and it was shown that for a known gas composition, predictions of the sensor response agreed well with experiment. In the present paper, the more ‘practical’ problem is addressed: how well can such a model predict λ and X_{O_2 } based on the sensor response? For IC engine applications, a chemistry model is required in order to predict λ, and such a model is also desirable for an accurate prediction of X_{O_2 }. A fast (matrix exponential) method of solving the Stefan-Maxwell equations is also introduced, which offers the possibility of a near real-time computation of λ and X_{O_2 }, with application, for example, to bench instruments. Extensive results are presented showing how the interpretation of the UEGO response may be compromised by uncertainties. These uncertainties may relate not only to the sensor itself, such as temperature, pressure and mean pore diameter, but also the chemistry model.

  10. A plastic optical fiber sensor for the dual sensing of temperature and oxygen

    NASA Astrophysics Data System (ADS)

    Lo, Yu-Lung; Chu, Chen-Shane

    2008-04-01

    This study presents a low-cost plastic optical fiber sensor for the dual sensing of temperature and oxygen. The sensor features a commercially available epoxy glue coated on the side-polished fiber surface for temperature sensing and a fluorinated xerogel doped with platinum tetrakis pentrafluoropheny porphine (PtTFPP) coated on the fiber end for oxygen sensing. The temperature and oxygen indicators are both excited using a UV LED light source with a wavelength of 380 nm. The luminescence emission spectra of the two indicators are well resolved and exhibit no cross-talk effects. Overall, the results indicate that the dual sensor presented in this study provides an ideal solution for the non-contact, simultaneous sensing of temperature and oxygen in general biological and medical applications.

  11. Oxygen Assessments Ensure Safer Medical Devices

    NASA Technical Reports Server (NTRS)

    2013-01-01

    A team at White Sands Test Facility developed a test method to evaluate fire hazards in oxygen-enriched environments. Wendell Hull and Associates, located in Las Cruces, New Mexico, entered a Space Act Agreement with NASA and now provides services including fire and explosion investigations, oxygen testing and training, and accident reconstruction and forensic engineering.

  12. Fiber Optic Raman Sensor to Monitor Concentration Ratio of Nitrogen and Oxygen in a Cryogenic Mixture

    NASA Technical Reports Server (NTRS)

    Tiwari, Vidhu S.; Kalluru, Rajamohan R.; Yueh, Fang-Yu; Singh, Jagdish P.; SaintCyr, William

    2007-01-01

    A spontaneous Raman scattering optical fiber sensor is developed for a specific need of NASA/SSC for long-term detection and monitoring of the quality of liquid oxygen (LOX) in the delivery line during ground testing of rocket engines. The sensor performance was tested in the laboratory and with different excitation light sources. To evaluate the sensor performance with different excitation light sources for the LOX quality application, we have used the various mixtures of liquid oxygen and liquid nitrogen as samples. The study of the sensor performance shows that this sensor offers a great deal of flexibility and provides a cost effective solution for the application. However, an improved system response time is needed for the real-time, quantitative monitoring of the quality of cryogenic fluids in harsh environment.

  13. Rapid assessment of oxygen transfer impact for Corynebacterium glutamicum.

    PubMed

    Käß, Friedrich; Prasad, Arjun; Tillack, Jana; Moch, Matthias; Giese, Heiner; Büchs, Jochen; Wiechert, Wolfgang; Oldiges, Marco

    2014-12-01

    Oxygen supply is crucial in industrial application of microbial systems, such as Corynebacterium glutamicum, but oxygen transfer is often neglected in early strain characterizations, typically done under aerobic conditions. In this work, a new procedure for oxygen transfer screening is presented, assessing the impact of maximum oxygen transfer conditions (OTRmax) within microtiter plate-based cultivation for enhanced throughput. Oxygen-dependent growth and productivity were characterized for C. glutamicum ATCC13032 and C. glutamicum DM1933 (lysine producer). Biomass and lysine product yield are affected at OTRmax below 14 mmol L(-1) h(-1) in a standardized batch process, but not by further increase of OTRmax above this threshold value indicating a reasonable tradeoff between power input and oxygen transfer capacity OTRmax. The described oxygen transfer screening allows comparative determination of metabolic robustness against oxygen transfer limitation and serves identification of potential problems or opportunities later created during scale-up. PMID:24981020

  14. Development of sensors for monitoring oxygen and free radicals in plant physiology

    NASA Astrophysics Data System (ADS)

    Chaturvedi, Prachee

    Oxygen plays a critical role in the physiology of photosynthetic organisms, including bioenergetics, metabolism, development, and stress response. Oxygen levels affect photosynthesis, respiration, and alternative oxidase pathways. Likewise, the metabolic rate of spatially distinct plant cells (and therefore oxygen flux) is known to be affected by biotic stress (e.g., herbivory) and environmental stress (e.g., salt/nutrient stress). During aerobic metabolism, cells produce reactive oxygen species (ROS) as a by product. Plants also produce ROS during adaptation to stress (e.g., abscisic acid (ABA) mediated stress responses). If stress conditions are prolonged, ROS levels surpass the capacity of detoxifying mechanisms within the cell, resulting in oxidative damage. While stress response pathways such as ABA-mediated mechanisms have been well characterized (e.g., water stress, inhibited shoot growth, synthesis of storage proteins in seeds), the connection between ROS production, oxygen metabolism and stress response remains unknown. In part, this is because details of oxygen transport at the interface of cell(s) and the surrounding microenvironment remains nebulous. The overall goal of this research was to develop oxygen and Free radical sensors for studying stress signaling in plants. Recent developments in nanomaterials and data acquisition systems were integrated to develop real-time, non-invasive oxygen and Free radical sensors. The availability of these sensors for plant physiologists is an exciting opportunity to probe the functional realm of cells and tissues in ways that were not previously possible.

  15. Automated data quality assessment of marine sensors.

    PubMed

    Timms, Greg P; de Souza, Paulo A; Reznik, Leon; Smith, Daniel V

    2011-01-01

    The automated collection of data (e.g., through sensor networks) has led to a massive increase in the quantity of environmental and other data available. The sheer quantity of data and growing need for real-time ingestion of sensor data (e.g., alerts and forecasts from physical models) means that automated Quality Assurance/Quality Control (QA/QC) is necessary to ensure that the data collected is fit for purpose. Current automated QA/QC approaches provide assessments based upon hard classifications of the gathered data; often as a binary decision of good or bad data that fails to quantify our confidence in the data for use in different applications. We propose a novel framework for automated data quality assessments that uses Fuzzy Logic to provide a continuous scale of data quality. This continuous quality scale is then used to compute error bars upon the data, which quantify the data uncertainty and provide a more meaningful measure of the data's fitness for purpose in a particular application compared with hard quality classifications. The design principles of the framework are presented and enable both data statistics and expert knowledge to be incorporated into the uncertainty assessment. We have implemented and tested the framework upon a real time platform of temperature and conductivity sensors that have been deployed to monitor the Derwent Estuary in Hobart, Australia. Results indicate that the error bars generated from the Fuzzy QA/QC implementation are in good agreement with the error bars manually encoded by a domain expert. PMID:22163714

  16. Automated Data Quality Assessment of Marine Sensors

    PubMed Central

    Timms, Greg P.; de Souza, Paulo A.; Reznik, Leon; Smith, Daniel V.

    2011-01-01

    The automated collection of data (e.g., through sensor networks) has led to a massive increase in the quantity of environmental and other data available. The sheer quantity of data and growing need for real-time ingestion of sensor data (e.g., alerts and forecasts from physical models) means that automated Quality Assurance/Quality Control (QA/QC) is necessary to ensure that the data collected is fit for purpose. Current automated QA/QC approaches provide assessments based upon hard classifications of the gathered data; often as a binary decision of good or bad data that fails to quantify our confidence in the data for use in different applications. We propose a novel framework for automated data quality assessments that uses Fuzzy Logic to provide a continuous scale of data quality. This continuous quality scale is then used to compute error bars upon the data, which quantify the data uncertainty and provide a more meaningful measure of the data’s fitness for purpose in a particular application compared with hard quality classifications. The design principles of the framework are presented and enable both data statistics and expert knowledge to be incorporated into the uncertainty assessment. We have implemented and tested the framework upon a real time platform of temperature and conductivity sensors that have been deployed to monitor the Derwent Estuary in Hobart, Australia. Results indicate that the error bars generated from the Fuzzy QA/QC implementation are in good agreement with the error bars manually encoded by a domain expert. PMID:22163714

  17. Online Sensor Calibration Assessment in Nuclear Power Systems

    SciTech Connect

    Coble, Jamie B.; Ramuhalli, Pradeep; Meyer, Ryan M.; Hashemian, Hash

    2013-06-01

    Safe, efficient, and economic operation of nuclear systems (nuclear power plants, fuel fabrication and storage, used fuel processing, etc.) relies on transmission of accurate and reliable measurements. During operation, sensors degrade due to age, environmental exposure, and maintenance interventions. Sensor degradation can affect the measured and transmitted signals, including sensor failure, signal drift, sensor response time, etc. Currently, periodic sensor recalibration is performed to avoid these problems. Sensor recalibration activities include both calibration assessment and adjustment (if necessary). In nuclear power plants, periodic recalibration of safety-related sensors is required by the plant technical specifications. Recalibration typically occurs during refueling outages (about every 18 to 24 months). Non-safety-related sensors also undergo recalibration, though not as frequently. However, this approach to maintaining sensor calibration and performance is time-consuming and expensive, leading to unnecessary maintenance, increased radiation exposure to maintenance personnel, and potential damage to sensors. Online monitoring (OLM) of sensor performance is a non-invasive approach to assess instrument calibration. OLM can mitigate many of the limitations of the current periodic recalibration practice by providing more frequent assessment of calibration and identifying those sensors that are operating outside of calibration tolerance limits without removing sensors or interrupting operation. This can support extended operating intervals for unfaulted sensors and target recalibration efforts to only degraded sensors.

  18. Fiber optic oxygen sensor detection system for harsh environments of aerospace applications

    NASA Astrophysics Data System (ADS)

    Kazemi, Alex A.; Mendoza, Edgar; Goswami, Kish; Kempen, Lothar

    2013-05-01

    This paper describes the first successful fiber optic oxygen detection sensor systems developed for the Boeing Delta IV Launch Vehicle harsh environment of engine section. It illustrates a novel multi-point fiber optic microsensor (optrode) based on dynamic luminescence quenching that was developed for measuring oxygen leak detection for the space applications. The sensor optrodes employ the quenching by oxygen of the fluorescence from a ruthenium complex. These optrodes were fabricated using Ruthenium-based fluorescent indicator immobilized in a porous glass rod placed at the end of multimode fiber. The light from a blue LED is launched into the optrode via a fiber optic bundle and used as the excitation source. The optrode's fluorescent emission intensity in the range of 0% to 10% oxygen is measured as a function of time. The measuring system is based on high reliability and low cost. The system consists of four units: 1) temperature compensated oxygen optrodes combined with an optical setup, 2) multipoint sensor communication fiber optic network cable, 3) digital/analogue optoelectronic signal processing unit with built-in micro controller for control of data acquisition and processing, and 4) a laptop computer for data display and storage. In testing, the sensor exhibited excellent response time and reversibility. To qualify the sensors, performed detail investigation for thermal, humidity, temperature, vibration and accelerate testing for life expectancy of harsh environmental of engine section. Extensive networking using MatLab were carried out for lab and actual field demonstrations.

  19. Design, Fabrication and Characterization of a Miniaturized Series-Connected Potentiometric Oxygen Sensor

    SciTech Connect

    Radhakrishnan, Rajesh; Virkar, Anil V.; Singhal, Subhash C.; Dunham, Glen C.; Marina, Olga A.

    2005-03-28

    Miniaturization of potentiometric sensors facilitates connecting many sensors in series to amplify the output. Miniaturized series-connected potentiometric sensors were developed on a silicon wafer by microfabrication techniques. The sensors consist of a thin film yttria stabilized zirconia (YSZ) electrolyte and Pt electrodes. The reference oxygen partial pressure is determined by a nickel - nickel oxide (Ni-NiO) mixture. The open circuit voltage (OCV) was tested in air at 300oC and was found to be lower than expected. The output of the net sensor increased almost linearly by connecting 10 sensors in series. Impedance spectroscopy was used to investigate the electrolyte and electrolyte/electrode interfaces using a two electrode configuration.

  20. Skeletal muscle and glioma oxygenation by carbogen inhalation in rats: a longitudinal study by EPR oximetry using single-probe implantable oxygen sensors.

    PubMed

    Hou, Huagang; Khan, Nadeem; Lariviere, Jean; Hodge, Sassan; Chen, Eunice Y; Jarvis, Lesley A; Eastman, Alan; Williams, Benjamin B; Kuppusamy, Periannan; Swartz, Harold M

    2014-01-01

    The feasibility of EPR oximetry using a single-probe implantable oxygen sensor (ImOS) was tested for repeated measurement of pO₂ in skeletal muscle and ectopic 9L tumors in rats. The ImOS (50 mm length) were constructed using nickel-chromium alloy wires, with lithium phthalocyanine (LiPc, oximetry probe) crystals loaded in the sensor loop and coated with AF 2400(®) Teflon. These ImOS were implanted into the skeletal muscle in the thigh and subcutaneous 9L tumors. Dynamic changes in tissue pO₂ were assessed by EPR oximetry at baseline, during tumor growth, and repeated hyperoxygenation with carbogen breathing. The mean skeletal muscle pO₂ of normal rats was stable and significantly increased during carbogen inhalation in experiments repeated for 12 weeks. The 9L tumors were hypoxic with a tissue pO₂ of 12.8 ± 6.4 mmHg on day 1; however, the response to carbogen inhalation varied among the animals. A significant increase in the glioma pO₂ was observed during carbogen inhalation on day 9 and day 14 only. In summary, EPR oximetry with ImOS allowed direct and longitudinal oxygen measurements in deep muscle tissue and tumors. The heterogeneity of 9L tumors in response to carbogen highlights the need to repeatedly monitor pO₂ to confirm tumor oxygenation so that such changes can be taken into account in planning therapies and interpreting results. PMID:24729220

  1. A Fiber Optic Catalytic Sensor for Neutral Atom Measurements in Oxygen Plasma

    PubMed Central

    Zaplotnik, Rok; Vesel, Alenka; Mozetic, Miran

    2012-01-01

    The presented sensor for neutral oxygen atom measurement in oxygen plasma is a catalytic probe which uses fiber optics and infrared detection system to measure the gray body radiation of the catalyst. The density of neutral atoms can be determined from the temperature curve of the probe, because the catalyst is heated predominantly by the dissipation of energy caused by the heterogeneous surface recombination of neutral atoms. The advantages of this sensor are that it is simple, reliable, easy to use, noninvasive, quantitative and can be used in plasma discharge regions. By using different catalyst materials the sensor can also be applied for detection of neutral atoms in other plasmas. Sensor design, operation, example measurements and new measurement procedure for systematic characterization are presented. PMID:22666005

  2. Validation of a spectroscopic sensor for the continuous, noninvasive measurement of muscle oxygen saturation and pH.

    PubMed

    Ellerby, G E C; Smith, C P; Zou, F; Scott, P; Soller, B R

    2013-08-01

    New patient monitoring technologies can noninvasively and directly provide an assessment of the adequacy of tissue perfusion through the simultaneous determination of muscle oxygen saturation (SmO2) and muscle pH (pHm). Non-pulsatile near infrared spectroscopy is used to determine these microvascular parameters. Two separate studies were conducted using an isolated perfused swine limb preparation to widely vary venous blood oxygen saturation (SviO2) and pH (pHvi) to assess the accuracy of a noninvasive sensor with the capability to simultaneously measure both parameters. The isolated limb model is necessary to establish equilibrium between the venous output of the perfusion circuit and the venule measurement of the spectroscopic sensor. The average absolute difference between SmO2 and SviO2 determined over 50 conditions of SviO2 between 13% and 83% on 3 pig limbs was 3.8% and the coefficient of determination (R(2)) was 0.95. The average absolute difference between pHm and pHvi determined over 69 conditions of pHvi between pHvi 6.9 and pHvi 7.5 on 3 pig limbs was 0.045 pH units with an R(2) of 0.92. Measured accuracy was acceptable to support clinically relevant decision making for the assessment of impaired tissue perfusion and acidosis. Sensors were also evaluated on human subjects. There was no statistical difference in SmO2 by gender or location when multiple sensors were evaluated on the right and left calf, deltoid, and thigh of resting men and women (N = 33). SmO2 precision for subjects at rest was 5.6% over the six locations with four different sensors. PMID:23859848

  3. Evaluation of the Linear Aerospike SR-71 Experiment (LASRE) Oxygen Sensor

    NASA Technical Reports Server (NTRS)

    Ennix, Kimberly A.; Corpening, Griffin P.; Jarvis, Michele; Chiles, Harry R.

    1999-01-01

    The Linear Aerospike SR-71 Experiment (LASRE) was a propulsion flight experiment for advanced space vehicles such as the X-33 and reusable launch vehicle. A linear aerospike rocket engine was integrated into a semi-span of an X-33-like lifting body shape (model), and carried on top of an SR-71 aircraft at NASA Dryden Flight Research Center. Because no flight data existed for aerospike nozzles, the primary objective of the LASRE flight experiment was to evaluate flight effects on the engine performance over a range of altitudes and Mach numbers. Because it contained a large quantity of energy in the form of fuel, oxidizer, hypergolics, and gases at very high pressures, the LASRE propulsion system posed a major hazard for fire or explosion. Therefore, a propulsion-hazard mitigation system was created for LASRE that included a nitrogen purge system. Oxygen sensors were a critical part of the nitrogen purge system because they measured purge operation and effectiveness. Because the available oxygen sensors were not designed for flight testing, a laboratory study investigated oxygen-sensor characteristics and accuracy over a range of altitudes and oxygen concentrations. Laboratory test data made it possible to properly calibrate the sensors for flight. Such data also provided a more accurate error prediction than the manufacturer's specification. This predictive accuracy increased confidence in the sensor output during critical phases of the flight. This paper presents the findings of this laboratory test.

  4. A dual sensor for real-time monitoring of glucose and oxygen

    PubMed Central

    Zhang, Liqiang; Su, Fengyu; Buizer, Sean; Lu, Hongguang; Gao, Weimin; Tian, Yanqing; Meldrum, Deirdre

    2013-01-01

    A dual glucose and oxygen sensor in a polymer format was developed. The dual sensor composed of a blue emitter as the glucose probe, a red emitter as an oxygen probe, and a yellow emitter as a built-in reference probe which does not respond to either glucose or oxygen. All the three probes were chemically immobilized in a polyacrylamide-based matrix. Therefore, the dual sensor possesses three well separated emission colors and ratiometric approach is applicable for analysis of the glucose and oxygen concentration at biological conditions. The sensor was applied for real-time monitoring of glucose and oxygen consumption of bacterial cells, Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis), and mammalian cells of mouse macrophage J774 and human cervical cancer HeLa cell lines. On the other hand, in order to achieve satisfactory sensing performance for glucose, compositions of the matrices among poly(2-hydroxyethyl methacrylate), polyacrylamide, and poly(6-aminohexyl methacrylamide) which is a linker polymer for grafting the glucose probe, were optimized. PMID:24090834

  5. A dual sensor for real-time monitoring of glucose and oxygen.

    PubMed

    Zhang, Liqiang; Su, Fengyu; Buizer, Sean; Lu, Hongguang; Gao, Weimin; Tian, Yanqing; Meldrum, Deirdre

    2013-12-01

    A dual glucose and oxygen sensor in a polymer format was developed. The dual sensor composed of a blue emitter as the glucose probe, a red emitter as an oxygen probe, and a yellow emitter as a built-in reference probe which does not respond to either glucose or oxygen. All the three probes were chemically immobilized in a polyacrylamide-based matrix. Therefore, the dual sensor possesses three well separated emission colors and ratiometric approach is applicable for analysis of the glucose and oxygen concentration at biological conditions. The sensor was applied for real-time monitoring of glucose and oxygen consumption of bacterial cells, Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis), and mammalian cells of mouse macrophage J774 and human cervical cancer HeLa cell lines. On the other hand, in order to achieve satisfactory sensing performance for glucose, compositions of the matrices among poly(2-hydroxyethyl methacrylate), polyacrylamide, and poly(6-aminohexyl methacrylamide) which is a linker polymer for grafting the glucose probe, were optimized. PMID:24090834

  6. Reversible potentiometric oxygen sensors based on polymeric and metallic film electrodes.

    PubMed

    Yim, H S; Meyerhoff, M E

    1992-09-01

    Various materials and sensor configurations that exhibit reversible potentiometric responses to the partial pressure of oxygen at room temperature in neutral pH solution are examined. In one arrangement, platinum electrodes are coated with plasticized poly(vinyl chloride) films doped with a cobalt(II) tetraethylene pentamine complex. For such sensors, potentiometric oxygen response is attributed to a mixed potential originating from the underlying platinum electrode surface as well as a change in redox potential of the Co(II)-tetren-doped film as the complex binds oxygen reversibly. The response due to the platinum surface is prolonged by the presence of the Co(II)-tetren/PVC film. Alternately, thin films of metallic copper, electrochemically deposited on platinum and/or sputtered or vapor deposited on a single crystal silicon substrate, may be used for reversible oxygen sensing. The long-term reversibility and potentiometric stability of such copper film-based sensors is enhanced (up to 1 month) by preventing the formation of cuprous oxide on the surfaces via the application of an external nonpolarizing cathodic current through the working electrode or by specifically using sputtered copper films that have [100] preferred crystal structures as determined by X-ray diffraction. The implications of these findings in relation to fabricating analytically useful potentiometric oxygen sensors are discussed. PMID:1416035

  7. Assessing Photosynthetic Oxygen Liberation Using a BBC Microcomputer.

    ERIC Educational Resources Information Center

    Love, Annette J. W.; Spragg, Robert M.

    1986-01-01

    Describes a technique which gives an automatic and accurate assessment of photosynthetic oxygen liberation with graphical results available immediately. This program takes readings from an oxygen electrode and a photocell simultaneously. The types of results and unique features of the technique are discussed. (ML)

  8. 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.

  9. Regulatory Implications of Structural Changes in Tyr201 of the Oxygen Sensor Protein FixL.

    PubMed

    Yamawaki, Takeo; Ishikawa, Haruto; Mizuno, Misao; Nakamura, Hiro; Shiro, Yoshitsugu; Mizutani, Yasuhisa

    2016-07-26

    FixL is a heme-based oxygen-sensing histidine kinase that induces the expression of nitrogen fixation genes under hypoxic conditions. Oxygen dissociation from heme iron in the sensor domain of FixL initiates protein conformational changes that are transmitted to the histidine kinase domain, activating autophosphorylation activity. Conversely, oxygen binding inhibits FixL kinase activity. It is essential to elucidate the changes that occur in the protein structure upon this oxygen dissociation for understanding of the allosteric transduction mechanism. We measured ultraviolet resonance Raman spectra of FixL and its mutants for deoxy, oxy, and carbonmonoxy forms to examine the changes in protein structure upon oxygen dissociation. The observed spectral changes indicated that Tyr201 and its neighboring residues undergo structural changes upon oxygen dissociation. Kinase assays showed that substitution of Tyr201 significantly decreased the inhibition of kinase activity upon oxygen binding. These data mean that weakening of the hydrogen bond of Tyr201 that is induced by oxygen dissociation is essential for inhibition of kinase activity. We also observed spectral changes in Tyr residues in the kinase domain upon oxygen dissociation from FixL, which is the first observation of oxygen-dependent structural changes in the kinase domain of FixL. The observed structural changes support the allosteric transduction pathway of FixL which we proposed previously [ Yano, S., Ishikawa, H., Mizuno, M., Nakamura, H., Shiro, Y., and Mizutani, Y. ( 2013 ) J. Phys. Chem. B 117 , 15786 - 15791 ]. PMID:27367650

  10. Methane-oxygen electrochemical coupling in an ionic liquid: a robust sensor for simultaneous quantification.

    PubMed

    Wang, Zhe; Guo, Min; Baker, Gary A; Stetter, Joseph R; Lin, Lu; Mason, Andrew J; Zeng, Xiangqun

    2014-10-21

    Current sensor devices for the detection of methane or natural gas emission are either expensive and have high power requirements or fail to provide a rapid response. This report describes an electrochemical methane sensor utilizing a non-volatile and conductive pyrrolidinium-based ionic liquid (IL) electrolyte and an innovative internal standard method for methane and oxygen dual-gas detection with high sensitivity, selectivity, and stability. At a platinum electrode in bis(trifluoromethylsulfonyl)imide (NTf2)-based ILs, methane is electro-oxidized to produce CO2 and water when an oxygen reduction process is included. The in situ generated CO2 arising from methane oxidation was shown to provide an excellent internal standard for quantification of the electrochemical oxygen sensor signal. The simultaneous quantification of both methane and oxygen in real time strengthens the reliability of the measurements by cross-validation of two ambient gases occurring within a single sample matrix and allows for the elimination of several types of random and systematic errors in the detection. We have also validated this IL-based methane sensor employing both conventional solid macroelectrodes and flexible microfabricated electrodes using single- and double-potential step chronoamperometry. PMID:25093213

  11. Fiber-optic fluorescence-quenching oxygen partial pressure sensor using platinum octaethylporphyrin.

    PubMed

    Davenport, John J; Hickey, Michelle; Phillips, Justin P; Kyriacou, Panayiotis A

    2016-07-20

    The development and bench testing of a fiber-optic oxygen sensor is described. The sensor is designed for measurement of tissue oxygen levels in the mucosa of the digestive tract. The materials and construction are optimized for insertion through the mouth for measurement in the lower esophagus. An oxygen-sensitive fluorescence-quenching film was applied as a solution of platinum octaethylporphyrin (PtOEP) poly(ethyl methacrylate) (PEMA) and dichloromethane and dip coated onto the distal tip of the fiber. The sensor was tested by comparing relative fluorescence when immersed in liquid water at 37°C, at a range of partial pressures (0-101 kPa). Maximum relative fluorescence at most oxygen concentrations was seen when the PtOEP concentration was 0.1  g.L-1, four layers of coating solution were applied, and a fiber core radius of 600 μm was selected, giving a Stern-Volmer constant of 0.129  kPa-1. The performance of the sensor is suitable for many in vivo applications, particularly mucosal measurements. It has sufficient sensitivity, is sterilizable, and is sufficiently flexible and robust for insertion via the mouth without damage to the probe or risk of harm to the patient. PMID:27463913

  12. Fluorophore-based sensor for oxygen radicals in processing plasmas

    SciTech Connect

    Choudhury, Faraz A.; Shohet, J. Leon; Sabat, Grzegorz; Sussman, Michael R.; Nishi, Yoshio

    2015-11-15

    A high concentration of radicals is present in many processing plasmas, which affects the processing conditions and the properties of materials exposed to the plasma. Determining the types and concentrations of free radicals present in the plasma is critical in order to determine their effects on the materials being processed. Current methods for detecting free radicals in a plasma require multiple expensive and bulky instruments, complex setups, and often, modifications to the plasma reactor. This work presents a simple technique that detects reactive-oxygen radicals incident on a surface from a plasma. The measurements are made using a fluorophore dye that is commonly used in biological and cellular systems for assay labeling in liquids. Using fluorometric analysis, it was found that the fluorophore reacts with oxygen radicals incident from the plasma, which is indicated by degradation of its fluorescence. As plasma power was increased, the quenching of the fluorescence significantly increased. Both immobilized and nonimmobilized fluorophore dyes were used and the results indicate that both states function effectively under vacuum conditions. The reaction mechanism is very similar to that of the liquid dye.

  13. A New Crosslinkable Oxygen Sensor Covalently Bonded into Poly(2-hydroxyethyl methacrylate)-CO-Polyacrylamide Thin Film for Dissolved Oxygen Sensing

    PubMed Central

    Tian, Yanqing; Shumway, Bradley R.; Meldrum, Deirdre R.

    2010-01-01

    A new oxygen sensor, compound 2, was synthesized through a chemical modification of a popularly used oxygen sensor of platinum(II)-5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorophenyl)-porphyrin (PtTFPP). The new sensor compound 2 possesses four crosslinkable methacrylate functional moieties, enabling it to be polymerized and crosslinked with other monomers for polymer sensing film (also called membrane) preparation. Using this characteristic, compound 2 was covalently bonded to hydrophilic poly(2-hydroxyethyl methacrylate)-co-polyacrylamide (referred to as PHEMA to simplify) and hydrophobic polystyrene (PS) films. To better understand the advantages and disadvantages of chemical crosslinking approaches and the influence of polymer matrices on sensing performance, PtTFPP was physically incorporated into the same PHEMA and PS matrices to compare. Response to dissolved oxygen (DO), leaching of the sensor molecules from their matrices, photostability of the sensors, and response time to DO changes were studied. It was concluded that the chemical crosslinking of the sensor compound 2 in polymer matrices: (i) alleviated the leaching problem of sensor molecules which usually occurred in the physically doped sensing systems and (ii) significantly improved sensors’ photostability. The PHEMA matrix was demonstrated to be more suitable for oxygen sensing than PS, because for the same sensor molecule, the oxygen sensitivity in PHEMA film was higher than that in PS and response time to DO change in the PHEMA film was faster than that in PS. It was the first time oxygen sensing films were successfully prepared using biocompatible hydrophilic PHEMA as a matrix, which does not allow leaching of the sensor molecules from the polymer matrix, has a faster response to DO changes than that of PS, and does not present cytotoxicity to human lung adenocarcinoma epithelial cells (A549). It is expected that the new sensor compound 2 and its similar compounds with chemically crosslinking

  14. An irradiation system for photodynamic therapy with a fiber-optic sensor for measuring tissue oxygen

    NASA Astrophysics Data System (ADS)

    Quintanar, L.; Fabila, D.; Stolik, S.; de la Rosa, J. M.

    2013-11-01

    Photodynamic Therapy is a well known treatment based on the interaction of light of specific wavelength with a photosensitizing drug. In the presence of oxygen molecules, the illumination of the photosensitizer can activate the production of reactive oxygen species, which leads to the death of target cells within the treated tissue. In order to obtain the best therapy response, the tissue oxygen concentration should be measured to adjust the therapy parameters before and during the treatment. In this work, an irradiation system for 5-Aminolevulinic Acid Photodynamic Therapy is presented. It allows the application of visible light radiation of 630 nm using as a light source a high-brightness light emitting diode with an optical-power automatic control considering a light depth-distribution model. A module to measure the tissue oxygen saturation has been implemented into the system. It is based on two light emitting diodes of 660 nm and 940 nm as light sources, a photodiode as a detector and a new handheld fiber optic reflectance pulse oximetry sensor for estimating the blood oxygen saturation within the tissue. The pulse oximetry sensor was modeled through multilayered Monte Carlo simulations to study the behavior of the sensor with changes in skin thickness and melanin content.

  15. Amperometric oxygen sensor based on a platinum nanoparticle-modified polycrystalline boron doped diamond disk electrode.

    PubMed

    Hutton, Laura; Newton, Mark E; Unwin, Patrick R; Macpherson, Julie V

    2009-02-01

    Pt nanoparticle (NP)-modified polycrystalline boron-doped diamond (pBDD) disk electrodes have been fabricated and employed as amperometric sensors for the determination of dissolved oxygen concentration in aqueous solution. pBDD columns were cut using laser micromachining techniques and sealed in glass, in order to make disk electrodes which were then characterized electrochemically. Electrodeposition of Pt onto the diamond electrodes was optimized so as to give the maximum oxygen reduction peak current with the lowest background signal. Pt NPs, >0-10 nm diameter, were found to deposit randomly across the pBDD electrode, with no preference for grain boundaries. The more conductive grains were found to promote the formation of smaller nanoparticles at higher density. With the use of potential step chronoamperometry, in which the potential was stepped to a diffusion-limited value, a four electron oxygen reduction process was found to occur at the Pt NP-modified pBDD electrode. Furthermore the chronoamperometric response scaled linearly with dissolved oxygen concentration, varied by changing the oxygen/nitrogen ratio of gas flowed into solution. The sensor was used to detect dissolved oxygen concentrations with high precision over the pH range 4-10. PMID:19117391

  16. The Preliminary Study Of Giant Magnetoresistance Sensor For Detection Of Oxygen In Human Blood

    NASA Astrophysics Data System (ADS)

    Ramli, Ramli; Muhtadi, Almas Hilman; Sahdan, Muhammad Fauzi; Haryanto, Freddy; Khairurrijal; Djamal, Mitra

    2010-12-01

    In recent years, there has been great progress for applications of nanomaterials in medicine field. Human body consists of many atoms and they can be treated like as nanomaterials. One of them is oxygen. Oxygen is always found in the human blood. Its concentration in human blood gives information about the metabolism in the body. The purpose of this study was to look for a possibility for developing tool to detect the concentration of oxygen in blood. In this study, the giant-magneto-resistance (GMR) sensor is implemented. The GMR sensor has many attractive features, for example: reduced size, low-power consumption, low price, as compared to other magnetic sensors and its electric and magnetic properties can be varied in very wide range. In this experiment, we developed the structure of GMR materials NiCoFe/Cu/NiCoFe sandwich as a GMR sensor. The NiCoFe/Cu/NiCoFe sandwiches were grown onto Si (111) substrates by the dc-opposed target magnetron sputtering (dc-OTMS) technique. The sputtering targets were NiCoFe and Cu. To achieve the aims of this study, the blood transports in human will be simulated using a simple experimental model. This model has some parameters representing those in blood transport. Furthermore, the nanomagnetic material will be made as a contaminant particle in blood. Using this material some properties of the transport will be investigated.

  17. Assessment of fiber optic pressure sensors

    SciTech Connect

    Hashemian, H.M.; Black, C.L.; Farmer, J.P.

    1995-04-01

    This report presents the results of a six-month Phase 1 study to establish the state-of-the-art in fiber optic pressure sensing and describes the design and principle of operation of various fiber optic pressure sensors. This study involved a literature review, contact with experts in the field, an industrial survey, a site visit to a fiber optic sensor manufacturer, and laboratory testing of a fiber optic pressure sensor. The laboratory work involved both static and dynamic performance tests. In addition, current requirements for environmental and seismic qualification of sensors for nuclear power plants were reviewed to determine the extent of the qualification tests that fiber optic pressure sensors may have to meet before they can be used in nuclear power plants. This project has concluded that fiber optic pressure sensors are still in the research and development stage and only a few manufacturers exist in the US and abroad which supply suitable fiber optic pressure sensors for industrial applications. Presently, fiber optic pressure sensors are mostly used in special applications for which conventional sensors are not able to meet the requirements.

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

    PubMed

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

    2012-11-20

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

  19. Fiber Optic Chemical Sensor For The Measurement Of Partial Pressure Of Oxygen

    NASA Astrophysics Data System (ADS)

    Goswami, Kisholoy; Klainer, Stanley M.; Tokar, John M.

    1989-01-01

    The estimation of partial pressure of oxygen in gaseous samples, aqueous samples and biological fluids has very important ramifications in environmental, medicinal and analytical chemistry. We have devised a fiber optic chemical sensor for the determination of oxygen concentration based on the dynamic luminescence quenching of a fluorophore bx oxygen. Ruthenium(II)tris(bipyridine), [Ru(bpy)3]4+, has been employed in our studies as the oxygen sensitive dye. The emission of Ru(bpy)32+ is centered at 610 nm and has a lifetime of 685 ns in argon purged aqueous solution. Our fiber optic chemical sensor consists of a custom built spectrometer containing argon ion laser light source, detector and associated electronics. A fiber optic cable is employed to guide light into and out of the spectrometer. A known amount of the sensing material in solution is used in a specially designed cell which has a gas permeable membrane at one end and the other end is coupled with the long cable to the spectrometer. Further research is being continued in improving the sensor chemistry and its dynamic detection range.

  20. A New Optical Oxygen Sensor Reveals Spatial and Temporal Variations of Dissolved Oxygen at Ecohydrological Interfaces

    NASA Astrophysics Data System (ADS)

    Brandt, T.; Schmidt, C.; Fleckenstein, J. H.; Vieweg, M.; Harjung, A.

    2015-12-01

    The spatial and temporal distribution of dissolved oxygen (DO) at highly reactive aquatic interfaces, e.g. in the hyporheic zone (HZ), is a primary indicator of redox and interlinked biogeochemical zonations. However, continuous measuring of DO over time and depths is challenging due to the dynamic and potentially heterogenic nature of the HZ. We further developed a novel technology for spatially continuous in situ vertical oxygen profiling based on optical sensing (Vieweg et al, 2013). Continuous vertical measurements to a depth of 50 cm are obtained by the motor-controlled insertion of a side-firing Polymer Optical Fiber (POF) into tubular DO probes. Our technology allows minimally invasive DO measurements without DO consumption at high spatial resolution in the mm range. The reduced size of the tubular probe (diameter 5 mm) substantially minimizes disturbance of flow conditions. We tested our technology in situ in the HZ of an intermittent stream during the drying period. Repeated DO measurements were taken over a total duration of six weeks at two locations up- and downstream of a pool-cascade sequence. We were able to precisely map the spatial DO distribution which exhibited sharp gradients and rapid temporal changes as a function of changing hydrologic conditions. Our new vertical oxygen sensing technology will help to provide new insights to the coupling of transport of DO and biogeochemical reactions at aquatic interfaces. Vieweg, M., Trauth, N., Fleckenstein, J. H., Schmidt, C. (2013): Robust Optode-Based Method for Measuring in Situ Oxygen Profiles in Gravelly Streambeds. Environmental Science & Technology. doi:10.1021/es401040w

  1. Response of electrochemical oxygen sensors to inert gas-air and carbon dioxide-air mixtures: measurements and mathematical modelling.

    PubMed

    Walsh, P T; Gant, S E; Dowker, K P; Batt, R

    2011-02-15

    Electrochemical oxygen gas sensors are widely used for monitoring the state of inertisation of flammable atmospheres and to warn of asphyxiation risks. It is well established but not widely known by users of such oxygen sensors that the response of the sensor is affected by the nature of the diluent gas responsible for the decrease in ambient oxygen concentration. The present work investigates the response of electrochemical sensors, with either acid or alkaline electrolytes, to gas mixtures comprising air with enhanced levels of nitrogen, carbon dioxide, argon or helium. The measurements indicate that both types of sensors over-read the oxygen concentrations when atmospheres contain high levels of helium. Sensors with alkaline electrolytes are also shown to underestimate the severity of the hazard in atmospheres containing high levels of carbon dioxide. This deviation is greater for alkaline electrolyte sensors compared to acid electrolyte sensors. A Computational Fluid Dynamics (CFD) model is developed to predict the response of an alkaline electrolyte, electrochemical gas sensor. Differences between predicted and measured sensor responses are less than 10% in relative terms for nearly all of the gas mixtures tested, and in many cases less than 5%. Extending the model to simulate responses of sensors with acid electrolytes would be straightforward. PMID:21112151

  2. Assessment of piezoelectric sensor adhesive bonding

    NASA Astrophysics Data System (ADS)

    Wandowski, T.; Moll, J.; Malinowski, P.; Opoka, S.; Ostachowicz, W.

    2015-07-01

    Piezoelectric transducers are widely utilized in Structural Health Monitoring (SHM). They are used both in guided wave-based and electromechanical impedance-based methods. Transducer debonding or unevenly distributed glue underneath the transducer reduce the performance and reliability of the SHM system. Therefore, quality assessment methods for glue layer need to be developed. In this paper, the authors present results obtained from two methods that allow the quality assessment of adhesive bonds of piezoelectric transducers. The electromechanical impedance method is utilized to analyze transducer adhesive bonding. An improperly prepared bonding layer is a source for changes in the electromechanical impedance characteristics in comparison to a perfectly bonded transducer. In the resistance characteristics of the properly bonded transducer the resonance peaks of the structure were clearly visible. In the case when adhesive layer is not equally distributed under sensor, the amplitudes of structural resonance peaks are reduced. In the case of completely detached transducer, the structural resonance peaks disappear and only resonance peaks of the transducer itself are visible. These peaks (peaks of free transducer hanging on wires) are significantly larger than the resonance peaks of the investigated structure in the considered frequency interval. The bonding layer shape is also analyzed using time-domain terahertz spectroscopy in reflection mode. This method allows to visualize the adhesive layer distribution based on C-scan analysis. C-scans of signals or envelope-detected signals can be used to estimate the area of proper adhesion between bonding agent and transducer and hence provides a more quantitative approach towards transducer inspection.

  3. Experimental studies on brain hematoma detection and oxygenation monitoring using PRM/NIR sensors

    NASA Astrophysics Data System (ADS)

    Zheng, Liu; Lee, Hyo Sang; Wilson, David A.; Hanley, Daniel F.; Lokos, Sandor; Kim, Jin

    1997-08-01

    Real time noninvasive head injury detection is needed in critical care facilities and triage site with limited resources. One tool missing right now is a small and fast noninvasive sensor which can help urgent care workers to (1) diagnose the location and severity of the injury, (2) to perform on site pre-hospital treatment if necessary, and (3) to make a decision on what kind of further medical action is needed. On the other hand, continuous monitoring of cerebral blood oxygenation is also needed in intensive care unit and in operation rooms. Pseudo-random modulation/near infrared sensor (PRM/NIR sensor) is developed to address these issues. It relies on advanced techniques in diode laser cw modulation and time resolved spectroscopy to perform fast and noninvasive brain tissue diagnostics. Phantom experiments have been conducted to study the feasibility of the sensor. Brain's optical properties are simulated with solutions of intralipid and ink. Hematomas are simulated with bags of paint and hemoglobin immersed in the solution of varies sizes, depths, and orientations. Effects of human skull and hair are studied experimentally. In animal experiment, the sensor was used to monitor the cerebral oxygenation change due to hypercapnia, hypoxia, and hyperventilation. Good correlations were found between NIR measurement parameters and physiological changes induced to the animals.

  4. Investigation of the electrode kinetics in a solid oxide fuel cell and an oxygen sensor

    NASA Astrophysics Data System (ADS)

    Radhakrishnan, Rajesh

    This dissertation investigates the electrode kinetics in a solid oxide fuel cell and an oxygen sensor. The first chapter describes the basics of fuel cell and motivation behind the studies. The second chapter investigates the dependence of cathodic charge transfer reaction resistance (Rct), on three-phase boundary length (lTPB) at various temperatures and oxygen partial pressures ( pO2 ). Impedance spectra were obtained using three-electrode configuration on discs having cathodes with definite lTPB to investigate the La0.8Sr0.2MnO3 (LSM)-Y 0.16Zr0.84O2 (YSZ), platinum (Pt)-YSZ and La 0.8Sr0.2CoO3 (LSC)-Ce0.8Sm0.2 O2 (SDC) half cell reactions at temperatures between 650--800°C and pO2 between 10-3 to 1 atm. For LSM-YSZ and Pt-YSZ, 1/Rct varies linearly with lTPB. LSC-SDC system did not show any specific dependence between R ct and lTPB. The third chapter examines the use of an electrolyte supported cell with externally applied voltage to determine the single electrode overpotential and extending the parameters derived to that of an anode supported fuel cell having thin film electrolyte operating under a chemical potential gradient. Spatial distributions of the electrochemical potential of electrons (ϕ) and oxygen ions ( m˜O-2 ), and chemical potential of oxygen ( mO2 ) for these two cases were obtained. Under fuel cell operating conditions, ϕ, m˜O-2 and mO2 , decreases monotonically from higher value to lower value. For electrolyte supported cell under externally applied voltage mO2 does not vary monotonically; it reaches values above or below that of the boundary values, leading to development of internal electromotive forces (EMFs), which can in turn affect the activity of the interface. The fourth chapter describes design microfabrication and characterization of a series connected potentiometric oxygen sensor. A drawback of potentiometric sensors in general is that the output signal is low when the ratio of the partial pressures at the two electrodes is low

  5. Quantifying oxygen in paper-based cell cultures with luminescent thin film sensors.

    PubMed

    Boyce, Matthew W; Kenney, Rachael M; Truong, Andrew S; Lockett, Matthew R

    2016-04-01

    Paper-based scaffolds are an attractive material for generating 3D tissue-like cultures because paper is readily available and does not require specialized equipment to pattern, cut, or use. By controlling the exchange of fresh culture medium with the paper-based scaffolds, we can engineer diffusion-dominated environments similar to those found in spheroids or solid tumors. Oxygen tension directly regulates cellular phenotype and invasiveness through hypoxia-inducible transcription factors and also has chemotactic properties. To date, gradients of oxygen generated in the paper-based cultures have relied on cellular response-based readouts. In this work, we prepared a luminescent thin film capable of quantifying oxygen tensions in apposed cell-containing paper-based scaffolds. The oxygen sensors, which are polystyrene films containing a Pd(II) tetrakis(pentafluorophenyl)porphyrin dye, are photostable, stable in culture conditions, and not cytotoxic. They have a linear response for oxygen tensions ranging from 0 to 160 mmHg O2, and a Stern-Volmer constant (K sv) of 0.239 ± 0.003 mmHg O2 (-1). We used these oxygen-sensing films to measure the spatial and temporal changes in oxygen tension for paper-based cultures containing a breast cancer line that was engineered to constitutively express a fluorescent protein. By acquiring images of the oxygen-sensing film and the fluorescently labeled cells, we were able to approximate the oxygen consumption rates of the cells in our cultures. Graphical Abstract Schematic of a paper-based culture seeded with fluorescent cells, and an oxygen-sensitive film. PMID:26667655

  6. Heme-based Globin-coupled Oxygen Sensors: Linking Oxygen Binding to Functional Regulation of Diguanylate Cyclase, Histidine Kinase, and Methyl-accepting Chemotaxis*

    PubMed Central

    Martínková, Markéta; Kitanishi, Kenichi; Shimizu, Toru

    2013-01-01

    An emerging class of novel heme-based oxygen sensors containing a globin fold binds and senses environmental O2 via a heme iron complex. Structure-function relationships of oxygen sensors containing a heme-bound globin fold are different from those containing heme-bound PAS and GAF folds. It is thus worth reconsidering from an evolutionary perspective how heme-bound proteins with a globin fold similar to that of hemoglobin and myoglobin could act as O2 sensors. Here, we summarize the molecular mechanisms of heme-based oxygen sensors containing a globin fold in an effort to shed light on the O2-sensing properties and O2-stimulated catalytic enhancement observed for these proteins. PMID:23928310

  7. Mitochondrial oxidative phosphorylation: tissue oxygen sensor for regulation of coronary flow.

    PubMed

    Nuutinen, E M; Wilson, D F; Erecińska, M

    1984-01-01

    The observation that mitochondrial oxidative phosphorylation in vivo is dependent on oxygen tension throughout the physiological range (Wilson et al., 1979a , 1979b ) has made this metabolic pathway the most probable candidate for the tissue oxygen sensor in the regulation of local blood flow. We have utilized the oxygen dependent regulatory system for coronary blood flow to examine this possibility. Alterations in coronary flow were induced by: 1. Varied work load; 2. Infusion of Amytal (an inhibitor of mitochondrial respiration); 3. Infusion of DNP; 4. Hypoxia. Increased work load caused increased coronary flow with no decrease in effluent oxygen tension while Amytal infusion and hypoxia caused vasodilation with increased and decreased O2 tension respectively. This indicates that oxygen tension per se cannot be responsible for the observed vasodilation. Tissue energy metabolism was evaluated by measuring metabolite levels in hearts which were freeze-clamped in each state of perfusion. In all four methods of vasodilation, a decrease in cellular energy state ratio ([ATP]f/[ADP]f[Pi]) expressed as the calculated ratio of free adenine nucleotides, was observed for conditions which increased flow. Systematic variation of work load, Amytal or DNP concentration resulted in quantitatively the same correlation between tissue [ATP]f/[ADP]f[Pi] and coronary flow. It is concluded that mitochondrial oxidative phosphorylation is the oxygen sensor for the regulation of coronary blood flow by tissue oxygen tension. Infusion of adenosine, a known coronary vasodilator, induced vasodilation which was completely blocked by theophylline.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:6731096

  8. Flexible Sheet-Type Sensor for Noninvasive Measurement of Cellular Oxygen Metabolism on a Culture Dish.

    PubMed

    Kojima, Mari; Takehara, Hiroaki; Akagi, Takanori; Shiono, Hirofumi; Ichiki, Takanori

    2015-01-01

    A novel flexible sensor was developed for the noninvasive oxygen metabolism measurement of cultivated cells and tissues. This device is composed of a transparent double-layered polymer sheet of ethylene-vinyl alcohol (EVOH) and poly(dimethylsiloxane) (PDMS) having an array of microhole structures of 90 μm diameter and 50 μm depth on its surface. All the microhole structures were equipped with a 1-μm-thick optical chemical sensing layer of platinum porphyrin-fluoropolymer on their bottom. The three-dimensional microstructures of the sensor were fabricated by a newly developed simple and low-cost production method named self-aligned hot embossing. The device was designed to be attached slightly above the cells cultivated on a dish to form a temporarily closed microspace over the target cells during measurement. Since the change in oxygen concentration is relatively fast in the microcompartmentalized culture medium, a rapid evaluation of the oxygen consumption rate is possible by measuring the phosphorescence lifetime of the platinum porphyrin-fluoropolymer. The combined use of the device and an automated optical measurement system enabled the high-throughput sensing of cellular oxygen consumption (100 points/min). We monitored the oxygen metabolism of the human breast cancer cell line MCF7 on a Petri dish and evaluated the oxygen consumption rate to be 0.72 ± 0.12 fmol/min/cell. Furthermore, to demonstrate the utility of the developed sensing system, we demonstrated the mapping of the oxygen consumption rate of rat brain slices and succeeded in visualizing a clear difference among the layer structures of the hippocampus, i.e., the cornu ammonis (CA1 and CA3) and dentate gyrus (DG). PMID:26624889

  9. Flexible Sheet-Type Sensor for Noninvasive Measurement of Cellular Oxygen Metabolism on a Culture Dish

    PubMed Central

    Akagi, Takanori; Shiono, Hirofumi; Ichiki, Takanori

    2015-01-01

    A novel flexible sensor was developed for the noninvasive oxygen metabolism measurement of cultivated cells and tissues. This device is composed of a transparent double-layered polymer sheet of ethylene-vinyl alcohol (EVOH) and poly(dimethylsiloxane) (PDMS) having an array of microhole structures of 90 μm diameter and 50 μm depth on its surface. All the microhole structures were equipped with a 1-μm-thick optical chemical sensing layer of platinum porphyrin-fluoropolymer on their bottom. The three-dimensional microstructures of the sensor were fabricated by a newly developed simple and low-cost production method named self-aligned hot embossing. The device was designed to be attached slightly above the cells cultivated on a dish to form a temporarily closed microspace over the target cells during measurement. Since the change in oxygen concentration is relatively fast in the microcompartmentalized culture medium, a rapid evaluation of the oxygen consumption rate is possible by measuring the phosphorescence lifetime of the platinum porphyrin-fluoropolymer. The combined use of the device and an automated optical measurement system enabled the high-throughput sensing of cellular oxygen consumption (100 points/min). We monitored the oxygen metabolism of the human breast cancer cell line MCF7 on a Petri dish and evaluated the oxygen consumption rate to be 0.72 ± 0.12 fmol/min/cell. Furthermore, to demonstrate the utility of the developed sensing system, we demonstrated the mapping of the oxygen consumption rate of rat brain slices and succeeded in visualizing a clear difference among the layer structures of the hippocampus, i.e., the cornu ammonis (CA1 and CA3) and dentate gyrus (DG). PMID:26624889

  10. A Novel Solid Electrolyte Oxygen Sensor System for In-Situ Measurement and Process Control

    NASA Astrophysics Data System (ADS)

    Hammer, Frank Uwe; Messerschmid, Ernst; Rogg, Markus

    2010-10-01

    In 1993 the oxygen partial pressure was firstly measured inside a plasma wind tunnel using conventional λ-probes. Since then, a considerable amount of knowledge has been gained in using these sensors in ground test facilities and space. However, these commercially available sensors were too large in scale and weight. Consequently, a new development of solid electrolyte sensors called FIPEX more feasible for space was initiated. Due to space driven benefits, interest arose to use FIPEX technique in terrestrial applications e.g. to monitor sputter plants for float glass coating. Therefore, the VacuSen® sensor was developed. The characterization of VacuSen® at nominal sensor temperature TS = 680° C resulted in a sensor current according to IS = bṡpO20ṡ8±0ṡ05 I[μA] in the operation range between ptot = 1ṡ10-3 to 5 Pa. From pulse width modulation (PWM) temperature control, additional information allows to measure ptot according to ptot = aṡRPWM0ṡ107±0ṡ005 thus enlarging the operation range to ptot = 1ṡ10-3 to 1ṡ105Pa. A one point calibration routine with air, ideally at ptot = 5 Pa in order to determine both calibration parameters a and b simultaneously, is proposed.

  11. Imaging Modalities to Assess Oxygen Status in Glioblastoma

    PubMed Central

    Corroyer-Dulmont, Aurélien; Chakhoyan, Ararat; Collet, Solène; Durand, Lucile; MacKenzie, Eric T.; Petit, Edwige; Bernaudin, Myriam; Touzani, Omar; Valable, Samuel

    2015-01-01

    Hypoxia, the result of an inadequacy between a disorganized and functionally impaired vasculature and the metabolic demand of tumor cells, is a feature of glioblastoma. Hypoxia promotes the aggressiveness of these tumors and, equally, negatively correlates with a decrease in outcome. Tools to characterize oxygen status are essential for the therapeutic management of patients with glioblastoma (i) to refine prognosis, (ii) to adapt the treatment regimen, and (iii) to assess the therapeutic efficacy. While methods that are focal and invasive in nature are of limited use, non-invasive imaging technologies have been developed. Each of these technologies is characterized by its singular advantages and limitations in terms of oxygenation status in glioblastoma. The aim of this short review is, first, to focus on the interest to characterize hypoxia for a better therapeutic management of patients and, second, to discuss recent and pertinent approaches for the assessment of oxygenation/hypoxia and their direct implication for patient care. PMID:26347870

  12. Sensitivity enhancement of carbon nanotube based ammonium ion sensors through surface modification by using oxygen plasma treatment

    SciTech Connect

    Yeo, Sanghak; Woong Jang, Chi; Lee, Seok; Min Jhon, Young; Choi, Changrok

    2013-02-18

    We have shown that the sensitivity of carbon nanotube (CNT) based sensors can be enhanced as high as 74 times through surface modification by using the inductively coupled plasma chemical vapor deposition method with oxygen. The plasma treatment power was maintained as low as 10 W within 20 s, and the oxygen plasma was generated far away from the sensors to minimize the plasma damage. From X-ray photoelectron spectroscopy analysis, we found that the concentration of oxygen increased with the plasma treatment time, which implies that oxygen functional groups or defect sites were generated on the CNT surface.

  13. Nitrite reductase function of deoxymyoglobin: oxygen sensor and regulator of cardiac energetics and function.

    PubMed

    Rassaf, Tienush; Flögel, Ulrich; Drexhage, Christine; Hendgen-Cotta, Ulrike; Kelm, Malte; Schrader, Jürgen

    2007-06-22

    Although the primary function of myoglobin (Mb) has been considered to be cellular oxygen storage and supply, recent studies have suggested to classify Mb as a multifunctional allosteric enzyme. In the heart, Mb acts as a potent scavenger of nitric oxide (NO) and contributes to the attenuation of oxidative damage. Here we report that a dynamic cycle exists in which a decrease in tissue oxygen tension drives the conversion of Mb from being an NO scavenger in normoxia to an NO producer in hypoxia. The NO generated by reaction of deoxygenated Mb with nitrite is functionally relevant and leads to a downregulation of cardiac energy status, which was not observed in mice lacking Mb. As a consequence, myocardial oxygen consumption is reduced and cardiac contractility is dampened in wild-type mice. We propose that this pathway represents a novel homeostatic mechanism by which a mismatch between oxygen supply and demand in muscle is translated into the fractional increase of deoxygenated Mb exhibiting enhanced nitrite reductase activity. Thus, Mb may act as an oxygen sensor which through NO can adjust muscle energetics to limited oxygen supply. PMID:17495223

  14. Central arterial pressure assessment with intensity POF sensor

    NASA Astrophysics Data System (ADS)

    Leitão, Cátia; Gonçalves, Steve; Antunes, Paulo; Bastos, José M.; Pinto, João. L.; André, Paulo

    2015-09-01

    The central pressure monitoring is considered a new key factor in hypertension assessment and cardiovascular prevention. In this work, it is presented the central arterial systolic pressure assessment with an intensity based POF sensor. The device was tested in four subjects, and stable pulse waves were obtained, allowing the calculation of the central pressure for all the subjects. The results shown that the sensor performs reliably, being a simple and low-cost solution to the intended application.

  15. A new layered sensor for simultaneous measurement of EMG, MMG and oxygen consumption at the same position.

    PubMed

    Kimoto, Akira; Yamada, Yuji

    2015-01-01

    A new layered sensor for simultaneous measurement of electromyography (EMG), mechanomyography (MMG) and oxygen consumption based on near-infrared spectroscopy (NIRS) at the same position of the muscle is presented. The proposed sensor is a layered structure of a thin stainless-steel electrode, a PVDF film with transparent electrodes and optical sensors. EMG, MMG and oxygen consumption based on NIRS are measured by the stainless-steel electrodes, PVDF film and optical sensors, respectively. Using the three types of data, muscular activity can be analyzed in more detail. Additionally, the proposed sensor system reduces the constraint of the sensors arranged on the skin in measurements at multiple points because three types of information, previously obtained with three types of general sensors, are detected by a pair of proposed sensors. In an experiment, simultaneous measurement of EMG, MMG and oxygen consumption via NIRS at the forearm was demonstrated using the proposed sensor under fluorescent light. The performance of the layered sensor was evaluated. PMID:25300403

  16. A micro-thermoelectric gas sensor for detection of hydrogen and atomic oxygen.

    PubMed

    Park, Se-Chul; Yoon, Seung-Il; Lee, Chung-il; Kim, Yong-Jun; Song, Soonho

    2009-02-01

    This paper demonstrates the fabrication and performance of a micro-thermoelectric gas sensor for an effective and inexpensive gas analysis system. The proposed micro-thermoelectric gas sensor was fabricated by using a surface micromachining technique. The sensing mechanism, consisting of thermoelectric material and a novel metal catalyst, was fabricated on the highly thermally resistive layer for reduced heat transfer to the substrate allowing for a simple fabrication process. The micro-thermoelectric gas sensor detects target gas species by measuring the reaction heat of the catalytic reaction between the target gas and a novel metal catalyst using Cu-Bi thermopiles. The catalytic reaction occurs only on the hot junction of the sensing thermopile where the metal catalyst is deposited. In order to reduce the external thermal noise, a difference between the output voltage of the sensing and the reference thermopiles was measured by using a differential amplifier. The response of the fabricated sensor was linear to temperature difference. The fabricated sensor can be used to detect various concentrations of hydrogen and atomic oxygen, where the output voltage linearly increased with the gas concentration. PMID:19173043

  17. Performance Evaluation of an Oxygen Sensor as a Function of the Samaria Doped Ceria Film Thickness

    SciTech Connect

    Sanghavi, Rahul P.; Nandasiri, Manjula I.; Kuchibhatla, Satyanarayana V N T; Nachimuthu, Ponnusamy; Engelhard, Mark H.; Shutthanandan, V.; Jiang, Weilin; Thevuthasan, Suntharampillai; Kayani, Asghar N.; Prasad, Shalini

    2010-12-01

    The current demand in the automobile industry is in the control of air-fuel mixture in the combustion engine of automobiles. Oxygen partial pressure can be used as an input parameter for regulating or controlling systems in order to optimize the combustion process. Our goal is to identify and optimize the material system that would potentially function as the active sensing material for such a device that monitors oxygen partial pressure in these systems. We have used thin film samaria doped ceria (SDC) as the sensing material for the sensor operation, exploiting the fact that at high temperatures, oxygen vacancies generated due to samarium doping act as conducting medium for oxygen ions which hop through the vacancies from one side to the other contributing to an electrical signal. We have recently established that 6 atom % Sm doping in ceria films has optimum conductivity. Based on this observation, we have studied the variation in the overall conductivity of 6 atom % samaria doped ceria thin films as a function of thickness in the range of 50 nm to 300 nm at a fixed bias voltage of 2 volts. A direct proportionality in the increase in the overall conductivity is observed with the increase in sensing film thickness. For a range of oxygen pressure values from 1 mTorr to 100 Torr, a tolerable hysteresis error, good dynamic response and a response time of less than 10 seconds was observed

  18. Fiber-optic dissolved oxygen and dissolved carbon dioxide sensors using fluorophores encapsulated in sol gel matrices

    NASA Astrophysics Data System (ADS)

    Kwon, Hyeog-Chan

    Fiber optic chemical sensors (FOCS) for oxygen, dissolved oxygen (DO), and dissolved CO2 sensing using thin films of fluorophores encapsulated in sol-gel matrices were made and tested. The DO/O2 sensor used ruthenium(II) tris(4,7-diphenyl-1,10-phenanthroline) perchlorate (Ru(Ph 2Phen)Cl2) as the oxygen sensitive fluorophore and methyltrimethoxysilane (MTMS) sol-gel as the encapsulating matrix material. For the DCO2 sensor, 8-hydroxy-1,3,6-pyrenetrisulfonic acid trisodium salt (HPTS) co-doped with sodium bicarbonate was used as the DCO2 sensitive fluorophore-chemical system and diisobutoxy-alumino triethoxysilane (ASE) sol-gel was used as the encapsulating matrix material. It was found that oxygen quenches the excited state Ru(Ph2Phen)Cl 2 by diffusing through the MTMS matrix. Continuous excitation of Ru(Ph 2Phen)Cl2 during MTMS drying resulted in long, single exponential lifetimes of the metal complex and increased sensor sensitivity. When the sensor was field tested, it was found to have an excellent match compared to conventional titration method for determining dissolved oxygen concentrations and had fast response times. It was determined that this sensor measured the vapor pressure of oxygen rather than the absolute concentration of dissolved oxygen. For DCO2 sensing, it was found that the dynamic response of the senor could be tuned by varying the HPTS to NaHCO3 ratios. The sensor had fast response times compared to other fiber optic DCO 2 sensors reported which typically have response times of minutes.

  19. Net community production at Ocean Station Papa observed with nitrate and oxygen sensors on profiling floats

    NASA Astrophysics Data System (ADS)

    Plant, Joshua N.; Johnson, Kenneth S.; Sakamoto, Carole M.; Jannasch, Hans W.; Coletti, Luke J.; Riser, Stephen C.; Swift, Dana D.

    2016-06-01

    Six profiling floats equipped with nitrate and oxygen sensors were deployed at Ocean Station P in the Gulf of Alaska. The resulting six calendar years and 10 float years of nitrate and oxygen data were used to determine an average annual cycle for net community production (NCP) in the top 35 m of the water column. NCP became positive in February as soon as the mixing activity in the surface layer began to weaken, but nearly 3 months before the traditionally defined mixed layer began to shoal from its winter time maximum. NCP displayed two maxima, one toward the end of May and another in August with a summertime minimum in June corresponding to the historical peak in mesozooplankton biomass. The average annual NCP was determined to be 1.5 ± 0.6 mol C m-2 yr-1 using nitrate and 1.5 ± 0.7 mol C m-2 yr-1 using oxygen. The results from oxygen data proved to be quite sensitive to the gas exchange model used as well as the accuracy of the oxygen measurement. Gas exchange models optimized for carbon dioxide flux generally ignore transport due to gas exchange through the injection of bubbles, and these models yield NCP values that are two to three time higher than the nitrate-based estimates. If nitrate and oxygen NCP rates are assumed to be related by the Redfield model, we show that the oxygen gas exchange model can be optimized by tuning the exchange terms to reproduce the nitrate NCP annual cycle.

  20. Automated navigation assessment for earth survey sensors using island targets

    NASA Technical Reports Server (NTRS)

    Patt, Frederick S.; Woodward, Robert H.; Gregg, Watson W.

    1997-01-01

    An automated method has been developed for performing navigation assessment on satellite-based Earth sensor data. The method utilizes islands as targets which can be readily located in the sensor data and identified with reference locations. The essential elements are an algorithm for classifying the sensor data according to source, a reference catalog of island locations, and a robust pattern-matching algorithm for island identification. The algorithms were developed and tested for the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), an ocean color sensor. This method will allow navigation error statistics to be automatically generated for large numbers of points, supporting analysis over large spatial and temporal ranges.

  1. Portable Nanoparticle-Based Sensors for Food Safety Assessment

    PubMed Central

    Bülbül, Gonca; Hayat, Akhtar; Andreescu, Silvana

    2015-01-01

    The use of nanotechnology-derived products in the development of sensors and analytical measurement methodologies has increased significantly over the past decade. Nano-based sensing approaches include the use of nanoparticles (NPs) and nanostructures to enhance sensitivity and selectivity, design new detection schemes, improve sample preparation and increase portability. This review summarizes recent advancements in the design and development of NP-based sensors for assessing food safety. The most common types of NPs used to fabricate sensors for detection of food contaminants are discussed. Selected examples of NP-based detection schemes with colorimetric and electrochemical detection are provided with focus on sensors for the detection of chemical and biological contaminants including pesticides, heavy metals, bacterial pathogens and natural toxins. Current trends in the development of low-cost portable NP-based technology for rapid assessment of food safety as well as challenges for practical implementation and future research directions are discussed. PMID:26690169

  2. Portable Nanoparticle-Based Sensors for Food Safety Assessment.

    PubMed

    Bülbül, Gonca; Hayat, Akhtar; Andreescu, Silvana

    2015-01-01

    The use of nanotechnology-derived products in the development of sensors and analytical measurement methodologies has increased significantly over the past decade. Nano-based sensing approaches include the use of nanoparticles (NPs) and nanostructures to enhance sensitivity and selectivity, design new detection schemes, improve sample preparation and increase portability. This review summarizes recent advancements in the design and development of NP-based sensors for assessing food safety. The most common types of NPs used to fabricate sensors for detection of food contaminants are discussed. Selected examples of NP-based detection schemes with colorimetric and electrochemical detection are provided with focus on sensors for the detection of chemical and biological contaminants including pesticides, heavy metals, bacterial pathogens and natural toxins. Current trends in the development of low-cost portable NP-based technology for rapid assessment of food safety as well as challenges for practical implementation and future research directions are discussed. PMID:26690169

  3. A Novel Solid Electrolyte Oxygen Sensor System for In-Situ Measurement and Process Control

    SciTech Connect

    Hammer, Frank Uwe; Messerschmid, Ernst; Rogg, Markus

    2010-10-13

    In 1993 the oxygen partial pressure was firstly measured inside a plasma wind tunnel using conventional {lambda}-probes. Since then, a considerable amount of knowledge has been gained in using these sensors in ground test facilities and space. However, these commercially available sensors were too large in scale and weight. Consequently, a new development of solid electrolyte sensors called FIPEX more feasible for space was initiated. Due to space driven benefits, interest arose to use FIPEX technique in terrestrial applications e.g. to monitor sputter plants for float glass coating. Therefore, the VacuSen registered sensor was developed. The characterization of VacuSen registered at nominal sensor temperature T{sub S} = 680 deg. C resulted in a sensor current according to I{sub S} = b{center_dot}p{sub O2}{sup 0{center_dot}8{+-}0{center_dot}05} I[{mu}A] in the operation range between p{sub tot} = 1{center_dot}10{sup -3} to 5 Pa. From pulse width modulation (PWM) temperature control, additional information allows to measure ptot according to p{sub tot} = a{center_dot}RPWM{sup 0{center_dot}107{+-}0{center_dot}005} thus enlarging the operation range to p{sub tot} = 1{center_dot}10{sup -3} to 1{center_dot}10{sup 5} Pa. A one point calibration routine with air, ideally at p{sub tot} = 5 Pa in order to determine both calibration parameters a and b simultaneously, is proposed.

  4. Toward Microbioreactor Arrays: A Slow-Responding Oxygen Sensor for Monitoring of Microbial Cultures in Standard 96-Well Plates.

    PubMed

    Glauche, Florian; John, Gernot T; Arain, Sarina; Knepper, Andreas; Neubauer, Antje; Goelling, Detlef; Lang, Christine; Violet, Norman; King, Rudibert; Neubauer, Peter

    2015-08-01

    In this study, a slow-responding chemo-optical sensor for dissolved oxygen (DO) integrated into a 96-well plate was developed. The slow response time ensures that the measured oxygen value does not change much during plate transport to the microplate reader. The sensor therefore permits at-line DO measurement of microbial cultures. Moreover, it eliminates the necessity of individual optical measurement systems for each culture plate, as many plates can be measured successively. Combined with the 96-well format, this increases the experimental throughput enormously. The novel sensor plate (Slow OxoPlate) consists of fluorophores suspended in a polymer matrix that were placed into u-bottom 96-well plates. Response time was measured using sodium sulfite, and a t90 value of 9.7 min was recorded. For application, DO values were then measured in Escherichia coli and Saccharomyces cerevisiae cultures grown under fed-batch-like conditions. Depending on the DO sensor's response time, different information on the oxygenation state of the culture plate was obtained: a fast sensor variant detects disturbance through sampling, whereas the slow sensor indicates oxygen limitation during incubation. A combination of the commercially available OxoPlate and the Slow OxoPlate enables operators of screening facilities to validate their cultivation procedures with regard to oxygen availability. PMID:25720599

  5. Gas-potentiometric method with solid electrolyte oxygen sensors for the investigation of combustion.

    PubMed

    Lorenz, H; Tittmann, K; Sitzki, L; Trippler, S; Rau, H

    1996-09-01

    Gas-potentiometric analysis using oxide-ion-conducting solid electrolytes as stabilized zirconia is a worthwhile method for the investigation of combustion processes. In the case of gas and oil flames specific parameters like the flame contour, the degree of burn-out and mixing can be determined and information about flame turbulence and reaction density can be gained from the temporal resolution of the sensor signal. Measurements carried out with solid electrolyte oxygen sensors in a fluidized bed show that combustion processes of solid fuels are also analyzable. This analysis results in fuel specific burn-out curves finally leading to burn-out times and to parameters of a macrokinetics of the combustion process as well as to ideas about the burn-out mechanism. From the resulting constants of the effective reaction rate a reactivity relative to bituminous coal coke can be given for any solid fuel. PMID:15048356

  6. Fast, Ultrasensitive Detection of Reactive Oxygen Species Using a Carbon Nanotube Based-Electrocatalytic Intracellular Sensor.

    PubMed

    Rawson, Frankie J; Hicks, Jacqueline; Dodd, Nicholas; Abate, Wondwossen; Garrett, David J; Yip, Nga; Fejer, Gyorgy; Downard, Alison J; Baronian, Kim H R; Jackson, Simon K; Mendes, Paula M

    2015-10-28

    Herein, we report a highly sensitive electrocatalytic sensor-cell construct that can electrochemically communicate with the internal environment of immune cells (e.g., macrophages) via the selective monitoring of a particular reactive oxygen species (ROS), hydrogen peroxide. The sensor, which is based on vertically aligned single-walled carbon nanotubes functionalized with an osmium electrocatalyst, enabled the unprecedented detection of a local intracellular "pulse" of ROS on a short second time scale in response to bacterial endotoxin (lipopolysaccharide-LPS) stimulation. Our studies have shown that this initial pulse of ROS is dependent on NADPH oxidase (NOX) and toll like receptor 4 (TLR4). The results suggest that bacteria can induce a rapid intracellular pulse of ROS in macrophages that initiates the classical innate immune response of these cells to infection. PMID:26438964

  7. Fast, Ultrasensitive Detection of Reactive Oxygen Species Using a Carbon Nanotube Based-Electrocatalytic Intracellular Sensor

    PubMed Central

    2015-01-01

    Herein, we report a highly sensitive electrocatalytic sensor-cell construct that can electrochemically communicate with the internal environment of immune cells (e.g., macrophages) via the selective monitoring of a particular reactive oxygen species (ROS), hydrogen peroxide. The sensor, which is based on vertically aligned single-walled carbon nanotubes functionalized with an osmium electrocatalyst, enabled the unprecedented detection of a local intracellular “pulse” of ROS on a short second time scale in response to bacterial endotoxin (lipopolysaccharide-LPS) stimulation. Our studies have shown that this initial pulse of ROS is dependent on NADPH oxidase (NOX) and toll like receptor 4 (TLR4). The results suggest that bacteria can induce a rapid intracellular pulse of ROS in macrophages that initiates the classical innate immune response of these cells to infection. PMID:26438964

  8. Feature Identification and Filtering for Engine Misfire Detection (EMD) Using Zirconia Oxygen Sensor

    NASA Astrophysics Data System (ADS)

    Pauzi, Muhammad Zaim Mohamed; Abu Bakar, Elmi; Fauzi Ismail, Mohd

    2016-02-01

    Vehicles as transportation are popular and mainly use among peoples around the world for various kind of purpose either personal or not. Over hundreds of year internal combustion engines widely used because of high efficiency and low maintenance compare to new technology which are using cells of battery. Nevertheless, emission cause of incomplete combustion such engine misfire normally occurs as well. For instances, some mechanical, sensors or actuators failure and environmental condition contribute to the engine misfire. The importance of engine misfire detection (EMD) is to ensure engine emissions not harmful to the environments and avoid damage of catalytic converter. By using low cost narrowband oxygen sensor to acquire air to fuel ratio (AFR) signal behavior under misfire condition and analyst by digital signal processing method using Discrete Fourier Transform (DFT) algorithm for Digital Butterworth Filter designation is discussed in this paper.

  9. Nanostructured Oxygen Sensor - Using Micelles to Incorporate a Hydrophobic Platinum Porphyrin

    PubMed Central

    Su, Fengyu; Alam, Ruhaniyah; Mei, Qian; Tian, Yanqing; Youngbull, Cody; Johnson, Roger H.; Meldrum, Deirdre R.

    2012-01-01

    Hydrophobic platinum(II)-5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorophenyl)-porphyrin (PtTFPP) was physically incorporated into micelles formed from poly(ε-caprolactone)-block-poly(ethylene glycol) to enable the application of PtTFPP in aqueous solution. Micelles were characterized using dynamic light scattering (DLS) and atomic force microscopy (AFM) to show an average diameter of about 140 nm. PtTFPP showed higher quantum efficiency in micellar solution than in tetrahydrofuran (THF) and dichloromethane (CH2Cl2). PtTFPP in micelles also exhibited higher photostability than that of PtTFPP suspended in water. PtTFPP in micelles exhibited good oxygen sensitivity and response time. This study provided an efficient approach to enable the application of hydrophobic oxygen sensors in a biological environment. PMID:22457758

  10. Two-Photon Absorbing Nanocrystal Sensors for Ratiometric Detection of Oxygen

    PubMed Central

    McLaurin, Emily J.; Greytak, Andrew B.; Bawendi, Moungi G.; Nocera, Daniel G.

    2012-01-01

    Two nanocrystal-osmium(II) polypyridyl (NC-Os(II)PP) conjugates have been designed to detect oxygen in biological environments. Polypyridines appended with a single free amine were linked with facility to a carboxylic acid functionality of a semiconductor NC overlayer to afford a biologically stable amide bond. The Os(II)PP complexes possess broad absorptions that extend into the red spectral region; this absorption feature makes them desirable acceptors of energy from NC donors. Fluorescence resonance energy transfer (FRET) from the NC to the Os(II)PP causes an enhanced Os(II)PP emission with a concomitant quenching of the NC emission. Owing to the large two-photon absorption cross-section of the NCs, FRET from NC to the Os(II)PP can be established under two-photon excitation conditions. In this way, two-photon processes of metal polypyridyl complexes can be exploited for sensing. The emission of the NC is insensitive to oxygen, even at 1 atm, whereas excited states of both osmium complexes are quenched in the presence of oxygen. The NC emission may thus be used as an internal reference to correct for fluctuations in the photoluminescence intensity signal. These properties taken together establish NC-Os(II)PP conjugates as competent ratiometric, two-photon oxygen sensors for application in biological microenvironments. PMID:19697933

  11. Laboratory and marine study of photoluminescent sensors of oxygen dissolved in seawater

    NASA Astrophysics Data System (ADS)

    Vlasov, V. L.; Konovalov, B. V.; Mosharov, V. E.; Radchenko, V. N.; Khanaev, S. A.; Khlebnikov, D. V.

    2010-02-01

    The laboratory and marine study of photoluminescent sensors developed at the TsAGI has been conducted to create a highly sensitivity gauge of the oxygen dissolved in seawater. The advantages of the photoluminescent gauge over the electrochemical ones are the following: zero sensitivity to electromagnetic fields, the pH of the water, and the hydrogen sulphide and ions of heavy metals in the water; zero oxygen consumption; and no need for the water to be pumped through the device. A breadboard model of the photoluminescent gauge with LED excitation of the luminescence has been built. The laboratory tests of the model demonstrated the accuracy of the gauge to be as high as 0.05 ml/1 in air at a response time of 0.3 s for 63% relaxation. Comparative field tests of the breadboard model and the SBE 43 electrochemical oxygen gauge (Sea-Bird Electronics Corp.) have shown good agreement of the estimates of the oxygen content in the water and clarified the prospects of model’s performance improvement.

  12. Resistive oxygen sensor using ceria-zirconia sensor material and ceria-yttria temperature compensating material for lean-burn engine.

    PubMed

    Izu, Noriya; Nishizaki, Sayaka; Shin, Woosuck; Itoh, Toshio; Nishibori, Maiko; Matsubara, Ichiro

    2009-01-01

    Temperature compensating materials were investigated for a resistive oxygen sensor using Ce(0.9)Zr(0.1)O(2) as a sensor material for lean-burn engines. The temperature dependence of a temperature compensating material should be the same as the sensor material; therefore, the Y concentration in CeO(2)-Y(2)O(3) was optimized. The resistance of Ce(0.5)Y(0.5)O(2-δ) was independent of the air-to-fuel ratio (oxygen partial pressure), so that it was confirmed to function as a temperature compensating material. Sensor elements comprised of Ce(0.9)Zr(0.1)O(2) and Ce(0.5)Y(0.5)O(2-δ) were fabricated and the output was determined to be approximately independent of the temperature in the wide range from 773 to 1,073 K. PMID:22291542

  13. Optimizing source detector separation for an implantable perfusion and oxygenation sensor

    NASA Astrophysics Data System (ADS)

    Akl, T. J.; King, T. J.; Long, R.; Baba, J. S.; McShane, M. J.; Ericson, M. N.; Wilson, M. A.; Coté, G. L.

    2011-03-01

    Each year thousands of patients are added to the waiting list for liver transplants. The first 7-10 days after transplant have proven to be the most critical in patient recovery and it is hypothesized that monitoring organ vital signals in this period can increase patient and graft survival rates. An implantable sensor to monitor the organ perfusion and oxygenation signals following surgery is being developed by our group. The sensor operates based on measuring diffuse reflection from three light emitting diodes (735, 805 and 940 nm). In this work the optimal source detector spacing to maximize oxygenation signal level is investigated for a portal vein model. Monte Carlo simulations provided signal levels and corresponding penetration depths as a function of separation between a point optical source and detector. The modeling results indicated a rapid decay in the optical signal with increasing distance. Through further analysis, it was found that there exists an optimal range of point source to detector spacing, between roughly 1 and 2 mm, in which the blood signal from the simulated portal vein was maximized. Overall, these results are being used to guide the placement and configuration of our probe for in vivo animal studies.

  14. Modeling the Effect of Oxygen on the Amperometric Response of Immobilized Organoselenium-Based S-Nitrosothiol Sensors

    PubMed Central

    Höfler, Lajos; Meyerhoff, Mark E.

    2011-01-01

    Amperometric detection of S-nitrosothiols (RSNOs) at sub-micromolar levels in blood samples is of potential importance for monitoring endothelial function and other disease states that involve changes in physiological nitric oxide (NO) production. It is shown here that the elimination of dissolved oxygen from samples is critical when using covalently attached diselenocystamine-based amperometric RSNO sensors for practical RSNO measurements. The newest generation of RSNO sensors utilizes an amperometric NO gas sensor with a thin organoselenium modified dialysis membrane mounted at the distal sensing tip. Sample RSNOs are catalytically reduced to NO within the dialysis membrane by the immobilized organoselenium species. In the presence of oxygen the sensitivity of these sensors for measuring low levels of RSNOs (< μM) is greatly reduced. It is demonstrated that the main scavenger of the generated nitric oxide is not the dissolved oxygen, but rather superoxide anion radical generated from the reaction of the reduced organoselenium species (the reactive species in the catalytic redox cycle) and dissolved oxygen. Computer simulations of the response of the RSNO sensor using rate constants and diffusion coefficients for the reactions involved, known from the literature or estimated from fitting to the observed amperometric response curves, as well as the specific geometric dimensions of the RSNO sensor, further support that nitric oxide and superoxide anion radical quickly react resulting in near zero sensor sensitivity toward RSNO concentrations in the sub-micromolar concentration range. Elimination of oxygen from samples helps improve sensor detection limits to ca. 10 nM levels of RSNOs. PMID:21230000

  15. Optical PEBBLE nanosensors and fiber optic sensors for real-time intracellular imaging and analysis of magnesium and oxygen

    NASA Astrophysics Data System (ADS)

    Park, Edwin J.

    A highly selective magnesium fluorescent optical nanosensor, made possible by PEBBLE (Probe Encapsulated By Biologically Localized Embedding) technology is presented. Ratiometric sensors were prepared, via a microemulsion polymerization process, by co-immobilizing a highly selective magnesium dye with a reference dye inside a polymer matrix. The resultant spherical sensors are ˜40 nm in diameter. Several dyes were investigated with coumarin 343 (C343) providing the best selectivity towards Mg2+ vs. ions such as Ca 2+, Na+, and K+. The dynamic range of the sensors was 1 to 30 mM (linear from 1 to 10 mM) with a response time of less than 4 s. The fully reversible sensors exhibit minimal leaching and photobleaching. In vitro intracellular changes in Mg2+ concentration were monitored in C6 Glioma cells. Preliminary experiments demonstrated the capability of these sensors thus they were used to investigate the PhoP/Q transmembrane protein system on the internal membrane of salmonella . The sensors were used to monitor the magnesium levels inside salmonella containing vacuoles. Previously believed hypotheses on changes in magnesium concentration are challenged with the newly obtained results. The selectivity for Mg2+ along with the biocompatibility of the matrix of these sensors provides a new and reliable tool for intracellular magnesium measurements. A second sensor platform was developed for the detection of intracellular dissolved oxygen, using a fiber optic probe. The design and fabrication of an oxygen fiber optic sensor based on the fluorescence quenching properties of the oxygen sensitive platinum (II) octaethylporphine ketone (PtOEPK) is presented. Octaethyl porphyrin (OEP) or bodipy maleimide 577/618, was also entrapped, as a reference dye, in a polyvinyl chloride matrix including the plasticizing agent bis 2-ethylhexyl sebacate (DOS). The multi mode fibers were pulled down to submicron dimensions and a dip coating procedure was used to apply the sensing

  16. Tuning the dynamic range and sensitivity of optical oxygen-sensors by employing differently substituted polystyrene-derivatives

    PubMed Central

    Koren, Klaus; Hutter, Lukas; Enko, Barbara; Pein, Andreas; Borisov, Sergey M.; Klimant, Ingo

    2013-01-01

    Ten different polystyrene-derivatives were tested with respect to their potential use as matrix materials for optical oxygen sensors in combination with the platinum(II) meso-tetra(4-fluorophenyl)tetrabenzoporphyrin as indicator dye. Either halogen atoms or bulky residues were introduced as substituents on the phenyl ring. A fine-tuning of the sensor sensitivity was achieved, without compromising solubility of the indicator in the matrix by providing a chemical environment very similar to polystyrene (PS), a standard matrix in optical oxygen sensors. To put the results into perspective, the studied materials were compared to PS regarding sensitivity of the sensor, molecular weight and glass-transition temperature. The materials promise to be viable alternatives to PS with respect to the requirements posed in various sensor application fields. Some of the polymers (e.g. poly(2,6-dichlorostyrene)) promise to be of use in applications requiring measurements from 0 to 100% oxygen due to linearity across this range. Poly(4-tert-butylstyrene) and poly(2,6-fluorostyrene), on the other hand, yield sensors with increased sensitivity. Sensor stability was evaluated as a function of the matrix, a topic which has not received a lot of interest so far. PMID:23576846

  17. A Novel Thermal Sensor for the Sensitive Measurement of Chemical Oxygen Demand

    PubMed Central

    Yao, Na; Liu, Zhuan; Chen, Ying; Zhou, Yikai; Xie, Bin

    2015-01-01

    A novel rapid methodology for determining the chemical oxygen demand (COD) based on a thermal sensor with a flow injection analysis system was proposed and experimentally validated. The ability of this sensor to detect and monitor COD was based on the degree of enthalpy increase when sodium hypochlorite reacted with the organic content in water samples. The measurement results were correlated with COD and were compared against the conventional method using potassium dichromate. The assay required only 5–7 min rather than the 2 h required for evaluation by potassium dichromate. The linear range was 5–1000 mg/L COD, and the limit of detection was very low, 0.74 mg/L COD. Moreover, this method exhibited high tolerance to chloride ions; 0.015 mol/L chloride ions had no influence on the response. Finally, the sensor was used to detect the COD of different water samples; the results were verified by the standard dichromate method. PMID:26295397

  18. Critical evaluation of oxygen-uptake assessment in swimming.

    PubMed

    Sousa, Ana; Figueiredo, Pedro; Pendergast, David; Kjendlie, Per-Ludvik; Vilas-Boas, João P; Fernandes, Ricardo J

    2014-03-01

    Swimming has become an important area of sport science research since the 1970s, with the bioenergetic factors assuming a fundamental performance-influencing role. The purpose of this study was to conduct a critical evaluation of the literature concerning oxygen-uptake (VO2) assessment in swimming, by describing the equipment and methods used and emphasizing the recent works conducted in ecological conditions. Particularly in swimming, due to the inherent technical constraints imposed by swimming in a water environment, assessment of VO2max was not accomplished until the 1960s. Later, the development of automated portable measurement devices allowed VO2max to be assessed more easily, even in ecological swimming conditions, but few studies have been conducted in swimming-pool conditions with portable breath-by-breath telemetric systems. An inverse relationship exists between the velocity corresponding to VO2max and the time a swimmer can sustain it at this velocity. The energy cost of swimming varies according to its association with velocity variability. As, in the end, the supply of oxygen (whose limitation may be due to central-O2 delivery and transportation to the working muscles-or peripheral factors-O2 diffusion and utilization in the muscles) is one of the critical factors that determine swimming performance, VO2 kinetics and its maximal values are critical in understanding swimmers' behavior in competition and to develop efficient training programs. PMID:24414133

  19. Real-time frequency domain temperature and oxygen sensor with a single optical fiber.

    PubMed

    Liao, S C; Xu, Z; Izatt, J A; Alcala, J R

    1997-11-01

    The combined excited-state phosphorescence life-times of an alexandrite crystal and platinum tetraphenylporphyrin Pt(TPP) in a single-fiber sensor are used to monitor temperature and oxygen concentration in the physiological range from 15-45 degrees C and 0-50% O2 with precision of 0.24 degree C and 0.15% O2 and accuracy of 0.28 degree C and 0.2% O2. A 500-micron cubic alexandrite crystal bound to the distal end of a 750-micron-diameter optical fiber core and the Pt(TPP) coated circumferentially with a length of 1 cm from the end of the same fiber are excited with pulsed super-bright blue LED light. This apparatus uses a 125-kHz sampler for data acquisition and frequency domain methods for signal processing. The instrument amplifies both the dc and ac components of the photomultiplier output and band limits the signal to 20 kHz. The fundamental frequency of the excitation is set to 488.3 Hz and the highest harmonic used is the 35th. This bandlimited signal is sampled and averaged over a few hundred cycles in the time domain. The frequency domain representation of the data is obtained by employing fast Fourier transform algorithms. The phase delay and the modulation ratio of each sampled harmonic are then computed. At least four log-spaced harmonic phases or modulations are averaged before decoding the two lifetimes of temperature and oxygen phosphorescent sensors. A component of zero lifetime is introduced to account for the excitation backscatter leakage through optical interference filters seen by the photodetector. Linear and second-order empirical polynomials are employed to compute the temperatures and oxygen concentrations from the inverse lifetimes. In the situation of constant oxygen concentration, the lifetime of Pt(TPP) changes with temperature but can be compensated using the measured temperature lifetime. The system drift is 0.24 degree C for the temperature measurement and 0.59% for the oxygen concentration measurement over 30 h of continuous operation

  20. Yeast-based Biochemical Oxygen Demand Sensors Using Gold-modified Boron-doped Diamond Electrodes.

    PubMed

    Ivandini, Tribidasari A; Harmesa; Saepudin, Endang; Einaga, Yasuaki

    2015-01-01

    A gold nanoparticle modified boron-doped diamond electrode was developed as a transducer for biochemical oxygen demand (BOD) measurements. Rhodotorula mucilaginosa UICC Y-181 was immobilized in a sodium alginate matrix, and used as a biosensing agent. Cyclic voltammetry was applied to study the oxygen reduction reaction at the electrode, while amperometry was employed to detect oxygen, which was not consumed by the microorganisms. The optimum waiting time of 25 min was observed using 1-mm thickness of yeast film. A comparison against the system with free yeast cells shows less sensitivity of the current responses with a linear dynamic range (R(2) = 0.99) of from 0.10 mM to 0.90 mM glucose (equivalent to 10 - 90 mg/L BOD) with an estimated limit of detection of 1.90 mg/L BOD. However, a better stability of the current responses could be achieved with an RSD of 3.35%. Moreover, less influence from the presence of copper ions was observed. The results indicate that the yeast-immobilized BOD sensors is more suitable to be applied in a real condition. PMID:26179128

  1. Muscle Oxygenation During Running Assessed by Broad Band NIRS.

    PubMed

    Steimers, A; Vafiadou, M; Koukourakis, G; Geraskin, D; Neary, P; Kohl-Bareis, M

    2016-01-01

    We used spatially resolved near-infrared spectroscopy (SRS-NIRS) to assess calf and thigh muscle oxygenation during running on a motor-driven treadmill. Two protocols were used: An incremental speed protocol was performed in 5-min stages, while a pacing paradigm modulated the step frequency (2.3 Hz [SLow]; 3.3 Hz [SHigh]) during a constant velocity for 2 min each. A SRS-NIRS broadband system was used to measure total haemoglobin concentration and oxygen saturation (SO2). An accelerometer was placed on the hip joints to measure limb acceleration through the experiment. The data showed that the calf desaturated to a significantly lower level than the thigh. During the pacing protocol, SO2 was significantly different between the high and low step frequencies. Additionally, physiological data as measured by spirometry were different between the SLow vs. SHigh pacing trials. Significant differences in VO2 at the same workload (speed) indicate alterations in mechanical efficiency. These data suggest that SRS broadband NIRS can be used to discern small changes in muscle oxygenation, making this device useful for metabolic exercise studies in addition to spirometry and movement monitoring by accelerometers. PMID:26782193

  2. Pipeline corrosion assessment using embedded Fiber Bragg grating sensors

    NASA Astrophysics Data System (ADS)

    Liang, Xiao; Huang, Ying; Galedari, Sahar Abuali; Azarmi, Fardad

    2015-04-01

    Corrosion is a leading cause of failure in metallic transmission pipelines. It significantly impacts the reliability and safety of metallic pipelines. An accurate assessment of corrosion status of the pipelines would contribute to timely pipeline maintenance and repair and extend the service life of the associated pipelines. To assess pipeline corrosion, various technologies have been investigated and the pipe-to-soil voltage potential measurement was commonly applied. However, remote and real-time corrosion assessment approaches are in urgent needs but yet achieved. Fiber optic sensors, especially, fiber Bragg gating (FBG) sensors, with unique advantages of real-time sensing, compactness, immune to EMI and moisture, capability of quasi-distributed sensing, and long life cycle, will be a perfect candidate for longterm pipeline corrosion assessment. In this study, FBG sensors are embedded inside pipeline external coating for corrosion monitoring of on-shore buried metallic transmission pipelines. Detail sensing principle, sensor calibration and embedment are introduced in this paper together with experimental corrosion evaluation testing ongoing. Upon validation, the developed sensing system could serve the purpose of corrosion monitoring to the numerous metallic pipelines across nation and would possibly reduce the pipeline corrosion induced tragedies.

  3. Fugitive methane assessment with mobile and fence line sensors

    EPA Science Inventory

    There is no published abstract for this short panel talk. The panel presentation titled “Fugitive methane assessment with mobile and fence line sensors” provides a basic introduction to the topic of next generation sensor technologies for identifying and fixing emiss...

  4. Studies of Hematopoietic Cell Differentiation with a Ratiometric and Reversible Sensor of Mitochondrial Reactive Oxygen Species

    PubMed Central

    Kaur, Amandeep; Jankowska, Karolina; Pilgrim, Chelsea; Fraser, Stuart T.

    2016-01-01

    Abstract Aims: Chronic elevations in cellular redox state are known to result in the onset of various pathological conditions, but transient increases in reactive oxygen species (ROS)/reactive nitrogen species (RNS) are necessary for signal transduction and various physiological functions. There is a distinct lack of reversible fluorescent tools that can aid in studying and unraveling the roles of ROS/RNS in physiology and pathology by monitoring the variations in cellular ROS levels over time. In this work, we report the development of ratiometric fluorescent sensors that reversibly respond to changes in mitochondrial redox state. Results: Photophysical studies of the developed flavin–rhodamine redox sensors, flavin–rhodamine redox sensor 1 (FRR1) and flavin–rhodamine redox sensor 2 (FRR2), confirmed the reversible response of the probes upon reduction and re-oxidation over more than five cycles. The ratiometric output of FRR1 and FRR2 remained unaltered in the presence of other possible cellular interferants (metals and pH). Microscopy studies indicated clear mitochondrial localization of both probes, and FRR2 was shown to report the time-dependent increase of mitochondrial ROS levels after lipopolysaccharide stimulation in macrophages. Moreover, it was used to study the variations in mitochondrial redox state in mouse hematopoietic cells at different stages of embryonic development and maturation. Innovation: This study provides the first ratiometric and reversible probes for ROS, targeted to the mitochondria, which reveal variations in mitochondrial ROS levels at different stages of embryonic and adult blood cell production. Conclusions: Our results suggest that with their ratiometric and reversible outputs, FRR1 and FRR2 are valuable tools for the future study of oxidative stress and its implications in physiology and pathology. Antioxid. Redox Signal. 24, 667–679. PMID:26865422

  5. Sensor Selection and Optimization for Health Assessment of Aerospace Systems

    NASA Technical Reports Server (NTRS)

    Maul, William A.; Kopasakis, George; Santi, Louis M.; Sowers, Thomas S.; Chicatelli, Amy

    2008-01-01

    Aerospace systems are developed similarly to other large-scale systems through a series of reviews, where designs are modified as system requirements are refined. For space-based systems few are built and placed into service these research vehicles have limited historical experience to draw from and formidable reliability and safety requirements, due to the remote and severe environment of space. Aeronautical systems have similar reliability and safety requirements, and while these systems may have historical information to access, commercial and military systems require longevity under a range of operational conditions and applied loads. Historically, the design of aerospace systems, particularly the selection of sensors, is based on the requirements for control and performance rather than on health assessment needs. Furthermore, the safety and reliability requirements are met through sensor suite augmentation in an ad hoc, heuristic manner, rather than any systematic approach. A review of the current sensor selection practice within and outside of the aerospace community was conducted and a sensor selection architecture is proposed that will provide a justifiable, defendable sensor suite to address system health assessment requirements.

  6. Sensor Selection and Optimization for Health Assessment of Aerospace Systems

    NASA Technical Reports Server (NTRS)

    Maul, William A.; Kopasakis, George; Santi, Louis M.; Sowers, Thomas S.; Chicatelli, Amy

    2007-01-01

    Aerospace systems are developed similarly to other large-scale systems through a series of reviews, where designs are modified as system requirements are refined. For space-based systems few are built and placed into service. These research vehicles have limited historical experience to draw from and formidable reliability and safety requirements, due to the remote and severe environment of space. Aeronautical systems have similar reliability and safety requirements, and while these systems may have historical information to access, commercial and military systems require longevity under a range of operational conditions and applied loads. Historically, the design of aerospace systems, particularly the selection of sensors, is based on the requirements for control and performance rather than on health assessment needs. Furthermore, the safety and reliability requirements are met through sensor suite augmentation in an ad hoc, heuristic manner, rather than any systematic approach. A review of the current sensor selection practice within and outside of the aerospace community was conducted and a sensor selection architecture is proposed that will provide a justifiable, dependable sensor suite to address system health assessment requirements.

  7. Characterization of a dissolved oxygen sensor made of plastic optical fiber coated with ruthenium-incorporated solgel.

    PubMed

    Chu, Fenghong; Yang, Junjie; Cai, Haiwen; Qu, Ronghui; Fang, Zujie

    2009-01-10

    A dissolved oxygen sensor made of plastic optical fiber as the substrate and dichlorotris (1, 10-phenanthroline) ruthenium as a fluorescence indicator is studied. Oxygen quenching characteristics of both intensity and phase were measured; the obtained characteristics showed deviation from the linear relation described by the Stern-Volmer equation. A two-layer model is proposed to explain the deviation, and main parameters can be deduced with the model. PMID:19137045

  8. Digital temperature sensor performance assessment report. [in simulated shuttle environments

    NASA Technical Reports Server (NTRS)

    Canniff, J. H.

    1974-01-01

    Performance assessment data accumulated during exposure of the digital temperature sensor to simulated shuttle flight type environments are presented. The test parameters were specifically designed to check the sensor for its: (1) ability to resolve temperature relative to the design specifications; (2) ability to maintain accuracy after interchanging the temperature probes with each electronics interface assembly; (3) stability (i.e., satisfactory operation and accuracy during and after exposure to flight environments); and (4) repeatability, or its ability to produce the same output on subsequent exposures to the identical stimulus. Equipment list, test descriptions, data summary, and conclusions are included.

  9. Assessment of the pivot shift using inertial sensors.

    PubMed

    Zaffagnini, Stefano; Signorelli, Cecilia; Grassi, Alberto; Yue, Han; Raggi, Federico; Urrizola, Francisco; Bonanzinga, Tommaso; Marcacci, Maurilio

    2016-06-01

    The pivot shift test is an important clinical tool used to assess the stability of the knee following an injury to the anterior cruciate ligament (ACL). Previous studies have shown that significant variability exists in the performance and interpretation of this manoeuvre. Accordingly, a variety of techniques aimed at standardizing and quantifying the pivot shift test have been developed. In recent years, inertial sensors have been used to measure the kinematics of the pivot shift. The goal of this study is to present a review of the literature and discuss the principles of inertial sensors and their use in quantifying the pivot shift test. PMID:26970757

  10. Ultrafast ligand rebinding in the heme domain of the oxygen sensors FixL and Dos: general regulatory implications for heme-based sensors.

    PubMed

    Liebl, Ursula; Bouzhir-Sima, Latifa; Negrerie, Michel; Martin, Jean-Louis; Vos, Marten H

    2002-10-01

    Heme-based oxygen sensors are part of ligand-specific two-component regulatory systems, which have both a relatively low oxygen affinity and a low oxygen-binding rate. To get insight into the dynamical aspects underlying these features and the ligand specificity of the signal transduction from the heme sensor domain, we used femtosecond spectroscopy to study ligand dynamics in the heme domains of the oxygen sensors FixL from Bradyrhizobium japonicum (FixLH) and Dos from Escherichia coli (DosH). The heme coordination with different ligands and the corresponding ground-state heme spectra of FixLH are similar to myoglobin (Mb). After photodissociation, the excited-state properties and ligand-rebinding kinetics are qualitatively similar for FixLH and Mb for CO and NO as ligands. In contrast to Mb, the transient spectra of FixLH after photodissociation of ligands are distorted compared with the ground-state difference spectra, indicating differences in the heme environment with respect to the unliganded state. This distortion is particularly marked for O(2). Strikingly, heme-O(2) recombination occurs with efficiency unprecedented for heme proteins, in approximately 5 ps for approximately 90% of the dissociated O(2). For DosH-O(2), which shows 60% sequence similarity to FixLH, but where signal detection and transmission presumably are quite different, a similarly fast recombination was found with an even higher yield. Altogether these results indicate that in these sensors the heme pocket acts as a ligand-specific trap. The general implications for the functioning of heme-based ligand sensors are discussed in the light of recent studies on heme-based NO and CO sensors. PMID:12271121

  11. A Phase Shift Demodulation Technique: Verification and Application in Fluorescence Phase Based Oxygen Sensors

    NASA Astrophysics Data System (ADS)

    Jia, Chuanwu; Chang, Jun; Wang, Fupeng; Jiang, Hao; Zhu, Cunguang; Wang, Pengpeng

    2016-06-01

    A phase shift demodulation technique based on subtraction capable of measuring 0.03 phase degree limit between sinusoidal signals is presented in this paper. A self-gain module and a practical subtracter act the kernel parts of the phase shift demodulation system. Electric signals in different phases are used to verify the performance of the system. In addition, a new designed optical source, laser fiber differential source (LFDS), capable of generating mini phase is used to further verify the system reliability. R-square of 0.99997 in electric signals and R-square of 0.99877 in LFDS are achieved, and 0.03 degree measurement limit is realized in experiments. Furthermore, the phase shift demodulation system is applied to the fluorescence phase based oxygen sensors to realize the fundamental function. The experimental results reveal that a good repetition and better than 0.02% oxygen concentration measurement accuracy are realized. In addition, the phase shift demodulation system can be easily integrated to other applications.

  12. Development of a compact multipass oxygen sensor used for gas diffusion studies in opaque media.

    PubMed

    Larsson, Jim; Mei, Liang; Lundin, Patrik; Bood, Joakim; Svanberg, Sune

    2015-11-20

    A highly scattering porous ceramic sample is employed as a miniature random-scattering multipass gas cell for monitoring of oxygen content in opaque media, that is, wood materials in the present work. Gas in scattering media absorption spectroscopy is used by employing a 760 nm near-infrared laser diode to probe the absorption of molecular oxygen enclosed in the pores of the ceramic material working as the multipass gas cell, with a porosity of 75%. A path length enhancement of approximately 26 times and a signal-to-noise ratio of about 60 were obtained for the ceramic sample used in this work. The gas sensor was then used in a case study of the gas diffusion in wood materials, namely, oak, spruce, and mahogany samples. Differences depending on whether gas diffusion was studied longitudinal or radial to the tree annual rings are demonstrated, with very little gas diffusing in the radial direction. We can also observe that the gas diffusion for the densest material-oak-had the fastest diffusion time, and mahogany, which had the lowest density, showed the slowest diffusion time. PMID:26836536

  13. Iridium-Based High-Sensitivity Oxygen Sensors and Photosensitizers with Ultralong Triplet Lifetimes.

    PubMed

    Jiang, Xinpeng; Peng, Jiang; Wang, Jianchun; Guo, Xinyan; Zhao, Dahui; Ma, Yuguo

    2016-02-17

    The photophysics of a series of bichromophoric molecules featuring an intramolecular triplet energy transfer between a triscyclometalated iridium(III) complex and covalently linked organic group are studied. By systematically varying the energy gap (0.1-0.3 eV) between the donor (metal complex) and acceptor (pyrene unit), reversible triplet energy transfer processes with equilibrium constant K ranging from ca. 500 to 40 000 are established. Unique photophysical consequences of such large K values are observed. Because of the highly imbalanced forward and backward energy transfer rates, triplet excitons dominantly populate the acceptor moiety in the steady state, giving rise to ultralong luminescence lifetimes up to 1-4 ms. Because the triscyclometalated Ir and triplet pyrene groups both impart relatively small nonradiative energy loss, decent phosphorescence quantum yields (Φ = 0.1-0.6) are attained in spite of the exceptionally prolonged excited states. By virtue of such precious combination of long-lived triplet state and high Φ, these bichromophoric molecules can serve as highly sensitive luminescent sensors for detecting trace amount of O2 and as potent photosensitizers for producing singlet oxygen even under low-oxygen content conditions. PMID:26592255

  14. Nanosized TiO[subscript 2] for Photocatalytic Water Splitting Studied by Oxygen Sensor and Data Logger

    ERIC Educational Resources Information Center

    Zhang, Ruinan; Liu, Song; Yuan, Hongyan; Xiao, Dan; Choi, Martin M. F.

    2012-01-01

    Photocatalytic water splitting by semiconductor photocatalysts has attracted considerable attention in the past few decades. In this experiment, nanosized titanium dioxide (nano-TiO[subscript 2]) particles are used to photocatalytically split water, which is then monitored by an oxygen sensor. Sacrificial reagents such as organics (EDTA) and metal…

  15. Application of Gas Sensor Arrays in Assessment of Wastewater Purification Effects

    PubMed Central

    Guz, Łukasz; Łagód, Grzegorz; Jaromin-Gleń, Katarzyna; Suchorab, Zbigniew; Sobczuk, Henryk; Bieganowski, Andrzej

    2015-01-01

    A gas sensor array consisting of eight metal oxide semiconductor (MOS) type gas sensors was evaluated for its ability for assessment of the selected wastewater parameters. Municipal wastewater was collected in a wastewater treatment plant (WWTP) in a primary sedimentation tank and was treated in a laboratory-scale sequential batch reactor (SBR). A comparison of the gas sensor array (electronic nose) response to the standard physical-chemical parameters of treated wastewater was performed. To analyze the measurement results, artificial neural networks were used. E-nose—gas sensors array and artificial neural networks proved to be a suitable method for the monitoring of treated wastewater quality. Neural networks used for data validation showed high correlation between the electronic nose readouts and: (I) chemical oxygen demand (COD) (r = 0.988); (II) total suspended solids (TSS) (r = 0.938); (III) turbidity (r = 0.940); (IV) pH (r = 0.554); (V) nitrogen compounds: N-NO3 (r = 0.958), N-NO2 (r = 0.869) and N-NH3 (r = 0.978); (VI) and volatile organic compounds (VOC) (r = 0.987). Good correlation of the abovementioned parameters are observed under stable treatment conditions in a laboratory batch reactor. PMID:25545263

  16. The role of oxygen in hydrogen sensing by a platinum-gate silicon carbide gas sensor: An ultrahigh vacuum study

    NASA Astrophysics Data System (ADS)

    Kahng, Yung Ho; Lu, Wei; Tobin, R. G.; Loloee, Reza; Ghosh, Ruby N.

    2009-03-01

    We report several experiments under ultrahigh vacuum conditions that elucidate the role of oxygen in the functioning of silicon carbide field-effect gas sensors with nonporous platinum gates. The devices studied are shown to be sensitive both to hydrogen and to propene. All of the results are consistent with oxygen acting through its surface reactions with hydrogen. Three specific aspects are highlighted: the need, under some conditions, for oxygen to reset the device to a fully hydrogen-depleted state; competition between hydrogen oxidation and hydrogen diffusion to metal/oxide interface sites, leading to steplike behavior as a function of the oxygen:hydrogen ratio (λ-sensing); and the removal of sulfur contamination by oxygen.

  17. Modeling of a three-source perfusion and blood oxygenation sensor for transplant monitoring using multilayer Monte Carlo code

    NASA Astrophysics Data System (ADS)

    Ibey, Bennett L.; Lee, Seungjoon; Ericson, M. Nance; Wilson, Mark A.; Cote, Gerard L.

    2004-06-01

    A Multi-Layer Monte Carlo (MLMC) model was developed to predict the results of in vivo blood perfusion and oxygenation measurement of transplanted organs as measured by an indwelling optical sensor. A sensor has been developed which uses three-source excitation in the red and infrared ranges (660, 810, 940 nm). In vitro data was taken using this sensor by changing the oxygenation state of whole blood and passing it through a single-tube pump system wrapped in bovine liver tissue. The collected data showed that the red signal increased as blood oxygenation increased and infrared signal decreased. The center wavelength of 810 nanometers was shown to be quite indifferent to blood oxygenation change. A model was developed using MLMC code that sampled the wavelength range from 600-1000 nanometers every 6 nanometers. Using scattering and absorption data for blood and liver tissue within this wavelength range, a five-layer model was developed (tissue, clear tubing, blood, clear tubing, tissue). The theoretical data generated from this model was compared to the in vitro data and showed good correlation with changing blood oxygenation.

  18. Activity of Daily Living assessment through wireless sensor data.

    PubMed

    Qing Zhang; Karunanithi, Mohan; Bradford, Dana; van Kasteren, Yasmin

    2014-01-01

    Activity of Daily Living has become a clinical de facto instrument to assess daily functional status of older people living independently at home. Almost all ADLs scales are based on subjective assessment of clinical staff and self-reported responses of the elderly person. A great deal of variability in ADL assessment is likely due to the different cultural beliefs, language and education, and over-assessment of personal capability to potentially avoid negative consequences. This paper proposes automatic and objective ADLs assessment as key component of a technology platform that supports older people to live independently in their home, called Smarter Safer Homes. The objective ADL assessment is achieved through communicating data from simple non-intrusive, wireless sensors placed in a home environment. Pilot sensor data sets were collected over six months from nine independent living homes of participants aged 70+ year. The application of a clustering based, unsupervised learning method on these data sets demonstrates the potential to automatically detect five domains of activity contributing to functional independence. Furthermore, the method provides features that support elderlys self-monitoring of daily activities more regularly, that could provide the potential for timely and early intervention from family and carers. PMID:25570315

  19. Intra-breath arterial oxygen oscillations detected by a fast oxygen sensor in an animal model of acute respiratory distress syndrome

    PubMed Central

    Formenti, F.; Chen, R.; McPeak, H.; Murison, P. J.; Matejovic, M.; Hahn, C. E. W.; Farmery, A. D.

    2015-01-01

    Background There is considerable interest in oxygen partial pressure (Po2) monitoring in physiology, and in tracking Po2 changes dynamically when it varies rapidly. For example, arterial Po2 (PaO2) can vary within the respiratory cycle in cyclical atelectasis (CA), where PaO2 is thought to increase and decrease during inspiration and expiration, respectively. A sensor that detects these PaO2 oscillations could become a useful diagnostic tool of CA during acute respiratory distress syndrome (ARDS). Methods We developed a fibreoptic Po2 sensor (<200 µm diameter), suitable for human use, that has a fast response time, and can measure Po2 continuously in blood. By altering the inspired fraction of oxygen (FIO2) from 21 to 100% in four healthy animal models, we determined the linearity of the sensor's signal over a wide range of PaO2 values in vivo. We also hypothesized that the sensor could measure rapid intra-breath PaO2 oscillations in a large animal model of ARDS. Results In the healthy animal models, PaO2 responses to changes in FIO2 were in agreement with conventional intermittent blood-gas analysis (n=39) for a wide range of PaO2 values, from 10 to 73 kPa. In the animal lavage model of CA, the sensor detected PaO2 oscillations, also at clinically relevant PaO2 levels close to 9 kPa. Conclusions We conclude that these fibreoptic PaO2 sensors have the potential to become a diagnostic tool for CA in ARDS. PMID:25631471

  20. Probabilistic Assessment of High-Throughput Wireless Sensor Networks

    PubMed Central

    Kim, Robin E.; Mechitov, Kirill; Sim, Sung-Han; Spencer, Billie F.; Song, Junho

    2016-01-01

    Structural health monitoring (SHM) using wireless smart sensors (WSS) has the potential to provide rich information on the state of a structure. However, because of their distributed nature, maintaining highly robust and reliable networks can be challenging. Assessing WSS network communication quality before and after finalizing a deployment is critical to achieve a successful WSS network for SHM purposes. Early studies on WSS network reliability mostly used temporal signal indicators, composed of a smaller number of packets, to assess the network reliability. However, because the WSS networks for SHM purpose often require high data throughput, i.e., a larger number of packets are delivered within the communication, such an approach is not sufficient. Instead, in this study, a model that can assess, probabilistically, the long-term performance of the network is proposed. The proposed model is based on readily-available measured data sets that represent communication quality during high-throughput data transfer. Then, an empirical limit-state function is determined, which is further used to estimate the probability of network communication failure. Monte Carlo simulation is adopted in this paper and applied to a small and a full-bridge wireless networks. By performing the proposed analysis in complex sensor networks, an optimized sensor topology can be achieved. PMID:27258270

  1. Probabilistic Assessment of High-Throughput Wireless Sensor Networks.

    PubMed

    Kim, Robin E; Mechitov, Kirill; Sim, Sung-Han; Spencer, Billie F; Song, Junho

    2016-01-01

    Structural health monitoring (SHM) using wireless smart sensors (WSS) has the potential to provide rich information on the state of a structure. However, because of their distributed nature, maintaining highly robust and reliable networks can be challenging. Assessing WSS network communication quality before and after finalizing a deployment is critical to achieve a successful WSS network for SHM purposes. Early studies on WSS network reliability mostly used temporal signal indicators, composed of a smaller number of packets, to assess the network reliability. However, because the WSS networks for SHM purpose often require high data throughput, i.e., a larger number of packets are delivered within the communication, such an approach is not sufficient. Instead, in this study, a model that can assess, probabilistically, the long-term performance of the network is proposed. The proposed model is based on readily-available measured data sets that represent communication quality during high-throughput data transfer. Then, an empirical limit-state function is determined, which is further used to estimate the probability of network communication failure. Monte Carlo simulation is adopted in this paper and applied to a small and a full-bridge wireless networks. By performing the proposed analysis in complex sensor networks, an optimized sensor topology can be achieved. PMID:27258270

  2. Thermally assisted sensor for conformity assessment of biodiesel production

    NASA Astrophysics Data System (ADS)

    Kawano, M. S.; Kamikawachi, R. C.; Fabris, J. L.; Muller, M.

    2015-02-01

    Although biodiesel can be intentionally tampered with, impairing its quality, ineffective production processes may also result in a nonconforming final fuel. For an incomplete transesterification reaction, traces of alcohol (ethanol or methanol) or remaining raw material (vegetable oil or animal fats) may be harmful to consumers, the environment or to engines. Traditional methods for biodiesel assessment are complex, time consuming and expensive, leading to the need for the development of new and more versatile processes for quality control. This work describes a refractometric fibre optic based sensor that is thermally assisted, developed to quantify the remaining methanol or vegetable oil in biodiesel blends. The sensing relies on a long period grating to configure an in-fibre interferometer. A complete analytical routine is demonstrated for the sensor allowing the evaluation of the biodiesel blends without segregation of the components. The results show the sensor can determine the presence of oil or methanol in biodiesel with a concentration ranging from 0% to 10% v/v. The sensor presented a resolution and standard combined uncertainty of 0.013% v/v and 0.62% v/v for biodiesel-oil samples, and 0.007% v/v and 0.22% v/v for biodiesel-methanol samples, respectively.

  3. Health assessment of gasoline and fuel oxygenate vapors: Neurotoxicity evaluation

    PubMed Central

    O’Callaghan, James P.; Daughtrey, Wayne C.; Clark, Charles R.; Schreiner, Ceinwen A.; White, Russell

    2016-01-01

    Sprague–Dawley rats were exposed via inhalation to vapor condensates of either gasoline or gasoline combined with various fuel oxygenates to assess potential neurotoxicity of evaporative emissions. Test articles included vapor condensates prepared from “baseline gasoline” (BGVC), or gasoline combined with methyl tertiary butyl ether (G/MTBE), ethyl t-butyl ether (G/ETBE), t-amyl methyl ether (G/TAME), diisopropyl ether (G/DIPE), ethanol (G/EtOH), or t-butyl alcohol (G/TBA). Target concentrations were 0, 2000, 10,000 or 20,000 mg/mg3 and exposures were for 6 h/day, 5 days/week for 13 weeks. The functional observation battery (FOB) with the addition of motor activity (MA) testing, hematoxylin and eosin staining of brain tissue sections, and brain regional analysis of glial fibrillary acidic protein (GFAP) were used to assess behavioral changes, traditional neuropathology and astrogliosis, respectively. FOB and MA data for all agents, except G/TBA, were negative. G/TBA behavioral effects resolved during recovery. Neuropathology was negative for all groups. Analyses of GFAP revealed increases in multiple brain regions largely limited to males of the G/EtOH group, findings indicative of minor gliosis, most significantly in the cerebellum. Small changes (both increases and decreases) in GFAP were observed for other test agents but effects were not consistent across sex, brain region or exposure concentration. PMID:24879970

  4. Health assessment of gasoline and fuel oxygenate vapors: neurotoxicity evaluation.

    PubMed

    O'Callaghan, James P; Daughtrey, Wayne C; Clark, Charles R; Schreiner, Ceinwen A; White, Russell

    2014-11-01

    Sprague-Dawley rats were exposed via inhalation to vapor condensates of either gasoline or gasoline combined with various fuel oxygenates to assess potential neurotoxicity of evaporative emissions. Test articles included vapor condensates prepared from "baseline gasoline" (BGVC), or gasoline combined with methyl tertiary butyl ether (G/MTBE), ethyl t-butyl ether (G/ETBE), t-amyl methyl ether (G/TAME), diisopropyl ether (G/DIPE), ethanol (G/EtOH), or t-butyl alcohol (G/TBA). Target concentrations were 0, 2000, 10,000 or 20,000mg/mg(3) and exposures were for 6h/day, 5days/week for 13weeks. The functional observation battery (FOB) with the addition of motor activity (MA) testing, hematoxylin and eosin staining of brain tissue sections, and brain regional analysis of glial fibrillary acidic protein (GFAP) were used to assess behavioral changes, traditional neuropathology and astrogliosis, respectively. FOB and MA data for all agents, except G/TBA, were negative. G/TBA behavioral effects resolved during recovery. Neuropathology was negative for all groups. Analyses of GFAP revealed increases in multiplebrain regions largely limited to males of the G/EtOH group, findings indicative of minor gliosis, most significantly in the cerebellum. Small changes (both increases and decreases) in GFAP were observed for other test agents but effects were not consistent across sex, brain region or exposure concentration. PMID:24879970

  5. Hardware performance assessment recommendations and tools for baropodometric sensor systems.

    PubMed

    Giacomozzi, Claudia

    2010-01-01

    Accurate plantar pressure measurements are mandatory in both clinical and research contexts. Differences in accuracy, precision, reliability of pressure measurement devices (PMDs) prevented so far the onset of standardization processes and of reliable reference datasets. The Italian National Institute of Health (ISS) approved and conducted a scientific project aimed to design, validate and implement dedicated testing methods for both in-factory and on-the-field PMD assessment. A general-purpose experimental set-up was built, complete and suitable for the assessment of PMDs based on different sensor technology, electronic conditioning and mechanical solutions. Preliminary assessments have been conducted on 5 commercial PMDs. The study lead to the definition of: i) an appropriate set of instruments and procedures for PMD technical assessment; ii) a minimum set of significant parameters for the technical characterization of the PMD performance; iii) some recommendations to both manufacturers and end users for an appropriate use in clinics and in research context. PMID:20567067

  6. Portable Imagery Quality Assessment Test Field for Uav Sensors

    NASA Astrophysics Data System (ADS)

    Dąbrowski, R.; Jenerowicz, A.

    2015-08-01

    Nowadays the imagery data acquired from UAV sensors are the main source of all data used in various remote sensing applications, photogrammetry projects and in imagery intelligence (IMINT) as well as in other tasks as decision support. Therefore quality assessment of such imagery is an important task. The research team from Military University of Technology, Faculty of Civil Engineering and Geodesy, Geodesy Institute, Department of Remote Sensing and Photogrammetry has designed and prepared special test field- The Portable Imagery Quality Assessment Test Field (PIQuAT) that provides quality assessment in field conditions of images obtained with sensors mounted on UAVs. The PIQuAT consists of 6 individual segments, when combined allow for determine radiometric, spectral and spatial resolution of images acquired from UAVs. All segments of the PIQuAT can be used together in various configurations or independently. All elements of The Portable Imagery Quality Assessment Test Field were tested in laboratory conditions in terms of their radiometry and spectral reflectance characteristics.

  7. A fibre optic oxygen sensor that detects rapid PO2 changes under simulated conditions of cyclical atelectasis in vitro.

    PubMed

    Formenti, Federico; Chen, Rongsheng; McPeak, Hanne; Matejovic, Martin; Farmery, Andrew D; Hahn, Clive E W

    2014-01-15

    Two challenges in the management of Acute Respiratory Distress Syndrome are the difficulty in diagnosing cyclical atelectasis, and in individualising mechanical ventilation therapy in real-time. Commercial optical oxygen sensors can detect [Formula: see text] oscillations associated with cyclical atelectasis, but are not accurate at saturation levels below 90%, and contain a toxic fluorophore. We present a computer-controlled test rig, together with an in-house constructed ultra-rapid sensor to test the limitations of these sensors when exposed to rapidly changing [Formula: see text] in blood in vitro. We tested the sensors' responses to simulated respiratory rates between 10 and 60 breaths per minute. Our sensor was able to detect the whole amplitude of the imposed [Formula: see text] oscillations, even at the highest respiratory rate. We also examined our sensor's resistance to clot formation by continuous in vivo deployment in non-heparinised flowing animal blood for 24h, after which no adsorption of organic material on the sensor's surface was detectable by scanning electron microscopy. PMID:24184746

  8. Conversion of a heme-based oxygen sensor to a heme oxygenase by hydrogen sulfide: effects of mutations in the heme distal side of a heme-based oxygen sensor phosphodiesterase (Ec DOS).

    PubMed

    Du, Yongming; Liu, Gefei; Yan, Yinxia; Huang, Dongyang; Luo, Wenhong; Martinkova, Marketa; Man, Petr; Shimizu, Toru

    2013-10-01

    The heme-based oxygen-sensor phosphodiesterase from Escherichia coli (Ec DOS), is composed of an N-terminal heme-bound oxygen sensing domain and a C-terminal catalytic domain. Oxygen (O2) binding to the heme Fe(II) complex in Ec DOS substantially enhances catalysis. Addition of hydrogen sulfide (H2S) to the heme Fe(III) complex in Ec DOS also remarkably stimulates catalysis in part due to the heme Fe(III)-SH and heme Fe(II)-O2 complexes formed by H2S. In this study, we examined the roles of the heme distal amino acids, M95 (the axial ligand of the heme Fe(II) complex) and R97 (the O2 binding site in the heme Fe(II)-O2 complex) of the isolated heme-binding domain of Ec DOS (Ec DOS-PAS) in the binding of H2S under aerobic conditions. Interestingly, R97A and R97I mutant proteins formed an oxygen-incorporated modified heme, verdoheme, following addition of H2S combined with H2O2 generated by the reactions. Time-dependent mass spectroscopic data corroborated the findings. In contrast, H2S did not interact with the heme Fe(III) complex of M95H and R97E mutants. Thus, M95 and/or R97 on the heme distal side in Ec DOS-PAS significantly contribute to the interaction of H2S with the Fe(III) heme complex and also to the modification of the heme Fe(III) complex with reactive oxygen species. Importantly, mutations of the O2 binding site of the heme protein converted its function from oxygen sensor to that of a heme oxygenase. This study establishes the novel role of H2S in modifying the heme iron complex to form verdoheme with the aid of reactive oxygen species. PMID:23736976

  9. Advanced Sensors and Controls for Building Applications: Market Assessment and Potential R&D Pathways

    SciTech Connect

    Brambley, M. R.; Haves, P.; McDonald, S. C.; Torcellini, P.; Hansen, D.; Holmberg, D. R.; Roth, K. W.

    2005-04-01

    This document provides a market assessment of existing building sensors and controls and presents a range of technology pathways (R&D options) for pursuing advanced sensors and building control strategies.

  10. Evaluation of intrusion sensors and video assessment in areas of restricted passage

    SciTech Connect

    Hoover, C.E.; Ringler, C.E.

    1996-04-01

    This report discusses an evaluation of intrusion sensors and video assessment in areas of restricted passage. The discussion focuses on applications of sensors and video assessment in suspended ceilings and air ducts. It also includes current and proposed requirements for intrusion detection and assessment. Detection and nuisance alarm characteristics of selected sensors as well as assessment capabilities of low-cost board cameras were included in the evaluation.

  11. Design, Fabrication and Characterization of a Miniaturized Series-Connected Potentiometric Oxygen Sensor

    SciTech Connect

    Radhakrishnan, Rajesh; Virkar, Anil V.; Singhal, Subhash C.; Dunham, Glen C.; Marina, Olga A.

    2004-07-24

    Miniaturization of potentiometric sensors facilitates connecting many sensors in series to amplify the output. Miniaturized series-connected potentiometric sensors were developed on silicon (Si) wafer by microfabrication techniques. The sensors consist of a thin nickel-nickel oxide (Ni-NiO) mixture. The open circuit voltage (OCV) was tested in air at 300 C and was found to be lower than expected. The output of the net sensor increased almost linearly by connecting 10 sensors in series. Impedance spectroscopy was used to investigate the electrolyte and electrolyte-electrode interfaces using a two electrode configuration.

  12. Assessing hafnium on hafnia as an oxygen getter

    SciTech Connect

    O'Hara, Andrew; Demkov, Alexander A.; Bersuker, Gennadi

    2014-05-14

    Hafnium dioxide or hafnia is a wide band gap dielectric used in a range of electronic applications from field effect transistors to resistive memory. In many of these applications, it is important to maintain control over oxygen stoichiometry, which can be realized in practice by using a metal layer, specifically hafnium, to getter oxygen from the adjacent dielectric. In this paper, we employ density functional theory to study the thermodynamic stability of an interface between (100)-oriented monoclinic hafnia and hafnium metal. The nudged elastic band method is used to calculate the energy barrier for migration of oxygen from the oxide to the metal. Our investigation shows that the presence of hafnium lowers the formation energy of oxygen vacancies in hafnia, but more importantly the oxidation of hafnium through the migration of oxygen from hafnia is favored energetically.

  13. Kinetics of nitric oxide and oxygen gases on porous Y-stabilized ZrO2-based sensors.

    PubMed

    Killa, Sajin; Cui, Ling; Murray, Erica P; Mainardi, Daniela S

    2013-01-01

    Using impedance spectroscopy the electrical response of sensors with various porous Y-stabilized ZrO2 (YSZ) microstructures was measured for gas concentrations containing 0-100 ppm NO with 10.5%O2 at temperatures ranging from 600-700 °C. The impedance response increased substantially as the sensor porosity increased from 46%-50%. Activation energies calculated based on data from the impedance measurements increased in magnitude (97.4-104.9 kJ/mol for 100 ppm NO) with respect to increasing YSZ porosity. Analysis of the oxygen partial pressure dependence of the sensors suggested that dissociative adsorption was the dominant rate limiting. The PWC/DNP theory level was used to investigate the gas-phase energy barrier of the 2NO+O2 → 2NO2 reaction on a 56-atom YSZ/Au model cluster using Density Functional Theory and Linear Synchronous Transit/Quadratic Synchronous Transit calculations. The reaction path shows oxygen surface reactions that begin with NO association with adsorbed O2 on a Zr surface site, followed by O2 dissociative adsorption, atomic oxygen diffusion, and further NO2 formation. The free energy barrier was calculated to be 181.7 kJ/mol at PWC/DNP. A qualitative comparison with the extrapolated data at 62% ± 2% porosity representing the YSZ model cluster indicates that the calculated barriers are in reasonable agreement with experiments, especially when the RPBE functional is used. PMID:23959196

  14. Fiber optic Raman sensor to monitor the concentration ratio of nitrogen and oxygen in a cryogenic mixture.

    PubMed

    Tiwari, Vidhu S; Kalluru, Rajamohan R; Yueh, Fang Y; Singh, Jagdish P; Cyr, William St; Khijwania, Sunil K

    2007-06-01

    A spontaneous Raman scattering optical fiber sensor was developed for a specific need of the National Aeronautics and Space Administration (NASA) for long-term detection and monitoring of the purity of liquid oxygen (LO(2)) in the oxidizer feed line during ground testing of rocket engines. The Raman peak intensity ratios for liquid nitrogen (LN(2)) and LO(2) with varied weight ratios (LN(2)/LO(2)) were analyzed for their applicability to impurity sensing. The study of the sensor performance with different excitation light sources has helped to design a miniaturized, cost-effective system for this application. The optimal system response time of this miniaturized sensor for LN(2)/LO(2) measurement was found to be in the range of a few seconds. It will need to be further reduced to the millisecond range for real-time, quantitative monitoring of the quality of cryogenic fluids in a harsh environment. PMID:17514292

  15. Health assessment of gasoline and fuel oxygenate vapors: immunotoxicity evaluation.

    PubMed

    White, Kimber L; Peachee, Vanessa L; Armstrong, Sarah R; Twerdok, Lorraine E; Clark, Charles R; Schreiner, Ceinwen A

    2014-11-01

    Female Sprague Dawley rats were exposed via inhalation to vapor condensates of either gasoline or gasoline combined with various fuel oxygenates to assess potential immunotoxicity of evaporative emissions. Test articles included vapor condensates prepared from "baseline gasoline" (BGVC), or gasoline combined with methyl tertiary butyl ether (G/MTBE), ethyl t-butyl ether (G/ETBE), t-amyl methyl ether (G/TAME), diisopropyl ether (G/DIPE), ethanol (G/EtOH), or t-butyl alcohol (G/TBA). Target concentrations were 0, 2000, 10,000 or 20,000mg/mg(3) administered for 6h/day, 5days/week for 4weeks. The antibody-forming cell (AFC) response to the T-dependent antigen, sheep erythrocyte (sRBC), was used to determine the effects of the gasoline vapor condensates on the humoral components of the immune system. Exposure to BGVC, G/MTBE, G/TAME, and G/TBA did not result in significant changes in the IgM AFC response to sRBC, when evaluated as either specific activity (AFC/10(6) spleen cells) or as total spleen activity (AFC/spleen). Exposure to G/EtOH and G/DIPE resulted in a dose-dependent decrease in the AFC response, reaching the level of statistical significance only at the high 20,000mg/m(3) level. Exposure to G/ETBE resulted in a statistically significant decrease in the AFC response at the middle (10,000mg/m(3)) and high (20,000mg/m(3)) exposure concentrations. PMID:24793263

  16. Spin label oximetry to assess extracellular oxygen during myocardial ischemia.

    PubMed

    Baker, J E; Froncisz, W; Joseph, J; Kalyanaraman, B

    1997-01-01

    We describe real-time measurement of myocardial oxygen consumption during ischemia in the intact heart. Measurement of extracellular oxygen concentration during myocardial ischemia by spin label oximetry has been limited by ischemia-induced reduction of the neutral, water-soluble nitroxide TEMPONE. We have overcome this problem by encapsulating the nitroxides. Isolated immature (7-10 d old) rabbit hearts (n = 8) were perfused aerobically within the cavity of a loop gap resonator with bicarbonate buffer containing an oxygen-sensitive, lipid-soluble nitroxide (14N-TEMPO laurate in FC-43 perfluorocarbon micelles) and a much less oxygen-sensitive and positively charged nitroxide (15N-TEMPO choline in multilamellar vesicles) as an internal standard. The ratio of the ESR signal amplitudes of these nitroxides was used as a sensitive index of oxygen concentration. Sequestration of the nitroxides decreased their reduction rate by ascorbate in comparison with nonsequestered nitroxides. Hearts were subjected to 60 min of global no-flow ischemia at 20 degrees C. Extracellular oxygen content (mean +/- SD) during aerobic perfusion was 1195 +/- 55 mumol/liter. The electron spin resonance signal from TEMPO laurate increased with the onset and progression of ischemia, consistent with a decrease in extracellular oxygen, while the signal for TEMPO choline was relatively unchanged. Extracellular oxygen content after 40 and 60 min of ischemia was reduced to 393 +/- 27 mumol/liter (p < .05) and 61 +/- 5 mumol/liter (p < .05), respectively. We conclude that spin-label oximetry can directly and precisely measure myocardial oxygen consumption at constant temperature during ischemia in the intact heart. PMID:8958135

  17. Quantitative Cherenkov emission spectroscopy for tissue oxygenation assessment

    PubMed Central

    Axelsson, Johan; Glaser, Adam K.; Gladstone, David J.; Pogue, Brian W.

    2012-01-01

    Measurements of Cherenkov emission in tissue during radiation therapy are shown to enable estimation of hemoglobin oxygen saturation non-invasively, through spectral fitting of the spontaneous emissions from the treated tissue. Tissue oxygenation plays a critical role in the efficacy of radiation therapy to kill tumor tissue. Yet in-vivo measurement of this has remained elusive in routine use because of the complexity of oxygen measurement techniques. There is a spectrally broad emission of Cherenkov light that is induced during the time of irradiation, and as this travels through tissue from the point of the radiation deposition, the tissue absorption and scatter impart spectral changes. These changes can be quantified by diffuse spectral fitting of the signal. Thus Cherenkov emission spectroscopy is demonstrated for the first time quantitatively in vitro and qualitatively in vivo, and has potential for real-time online tracking of tissue oxygen during radiation therapy when fully characterized and developed. PMID:22418319

  18. An oxidase-based electrochemical fluidic sensor with high-sensitivity and low-interference by on-chip oxygen manipulation.

    PubMed

    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

  19. Oxygen-independent FbFP: Fluorescent sentinel and oxygen sensor component in Saccharomyces cerevisiae and Candida albicans.

    PubMed

    Eichhof, Isabel; Ernst, Joachim F

    2016-07-01

    FMN-binding fluorescent proteins (FbFPs) outperform GFP and its derivatives because of their oxygen-independence, small size and rapid maturation. FbFPs have been used successfully as reliable reporters of gene expression in the cytoplasm of pro- and eukaryotes. Here we extend previous findings on the codon-adapted CaFbFP variant, which functions in the apathogenic yeast Saccharomyces cerevisiae and the human fungal pathogen Candida albicans. In both fungal species, CaFbFP could be targeted to the nucleus and the cell wall by endogenous signals (H2B-/Aga2-fusions) demonstrating its use as a fluorescent beacon in these relevant cellular locations. Transformants of both fungal species producing a CaFbFP-YFP fusion (YFOS) showed variable energy transfer from CaFbFP to YFP (FRET) that depended in its extent on external O2 concentrations. Applications as fluorescent sentinel and oxygen biosensor expand the FbFP toolbox to study oxygen-independent cellular processes under hypoxia. PMID:27126475

  20. Photoexcited ZnO nanoparticles with controlled defects as a highly sensitive oxygen sensor

    NASA Astrophysics Data System (ADS)

    Goto, Taku; Shimizu, Yoshiki; Yasuda, Hidehiro; Ito, Tsuyohito

    2016-07-01

    Conductance of photoexcited ZnO nanoparticles with various defects has been investigated in oxygen. ZnO nanoparticles, which show strong photoluminescence peaks originating from interstitial zinc atom (Zni) and singly charged oxygen vacancy (VO+), show oxygen-pressure-dependent conductance changes caused by photoexcitation. Herein, a model is proposed to simulate the conductance changes.

  1. Highly distributed multi-point, temperature and pressure compensated, fiber optic oxygen sensors (FOxSense) for aircraft fuel tank environment and safety monitoring

    NASA Astrophysics Data System (ADS)

    Mendoza, Edgar A.; Kempen, Cornelia; Sun, Sunjian; Esterkin, Yan

    2014-09-01

    This paper describes recent progress towards the development and qualification of a highly distributed, multi-point, all optical pressure and temperature compensated, fiber optic oxygen sensor (FOxSense™) system for closed-loop monitoring and safety of the oxygen ullage environment inside fuel tanks of military and commercial aircraft. The alloptical FOxSense™ system uses a passive, multi-parameter (O2/T&P) fiber optic sensor probe with no electrical connections leading to the sensors install within the fuel tanks of an aircraft. The all optical sensor consists of an integrated multi-parameter fiber optic sensor probe that integrates a fuel insensitive fluorescence based optical oxygen optrode with built-in temperature and pressure optical optrodes for compensation of temperature and pressure variants induced in the fluorescence response of the oxygen optrode. The distributed (O2/T&P) fiber optic sensors installed in the fuel tanks of the aircraft are connected to the FOxSense optoelectronic system via a fiber optic cable conduit reaching to each fuel tank in the aircraft. A multichannel frequency-domain fiber optic sensor read-out (FOxSense™) system is used to interrogate the optical signal of all three sensors in real-time and to display the fuel tank oxygen environment suitable for aircraft status and alarm applications. Preliminary testing of the all optical fiber optic oxygen sensor have demonstrated the ability to monitor the oxygen environment inside a simulated fuel tank in the range of 0% O2 to 40% O2 concentrations, temperatures from (-) 40°C to (+) 60°C, and altitudes from 0-ft to 40,000-ft.

  2. Assessment of hand kinematics using inertial and magnetic sensors

    PubMed Central

    2014-01-01

    Background Assessment of hand kinematics is important when evaluating hand functioning. Major drawbacks of current sensing glove systems are lack of rotational observability in particular directions, labour intensive calibration methods which are sensitive to wear and lack of an absolute hand orientation estimate. Methods We propose an ambulatory system using inertial sensors that can be placed on the hand, fingers and thumb. It allows a full 3D reconstruction of all finger and thumb joints as well as the absolute orientation of the hand. The system was experimentally evaluated for the static accuracy, dynamic range and repeatability. Results The RMS position norm difference of the fingertip compared to an optical system was 5±0.5 mm (mean ± standard deviation) for flexion-extension and 12.4±3.0 mm for combined flexion-extension abduction-adduction movements of the index finger. The difference between index and thumb tips during a pinching movement was 6.5±2.1 mm. The dynamic range of the sensing system and filter was adequate to reconstruct full 80 degrees movements of the index finger performed at 116 times per minute, which was limited by the range of the gyroscope. Finally, the reliability study showed a mean range difference over five subjects of 1.1±0.4 degrees for a flat hand test and 1.8±0.6 degrees for a plastic mold clenching test, which is smaller than other reported data gloves. Conclusion Compared to existing data gloves, this research showed that inertial and magnetic sensors are of interest for ambulatory analysis of the human hand and finger kinematics in terms of static accuracy, dynamic range and repeatability. It allows for estimation of multi-degree of freedom joint movements using low-cost sensors. PMID:24746123

  3. Clinical frailty syndrome assessment using inertial sensors embedded in smartphones.

    PubMed

    Galán-Mercant, A; Cuesta-Vargas, A I

    2015-09-01

    The aim of this study was to identify the series of kinematic variables demonstrating the greatest precision in discriminating between the function of two groups of elderly persons (frail and non-frail) in the 10 m expanded timed up and go (ETUG) test using inertial sensors embedded in the iPhone 4(®). A cross-sectional study was conducted to identify the kinematic variables with the highest degree of precision in discriminating between the two groups. The predicted capability of the kinematic variables was evaluated using receiver operating characteristic curves. The sample comprised 30 participants over 65 years old, 14 frail and 16 non-frail, assessed for frailty syndrome using the Fried criteria. Acceleration variables discriminated between the participant groups in the study; specifically these were the peak negative acceleration variables for motion axes x, y and z. In terms of sensitivity, the values were greater than or equal to those for the variable traditionally used to discriminate in the ETUG test, namely time. The kinematic parameters obtained from the internal inertial sensors in the iPhone 4(®) are promising additions to the ETUG analysis. There are encouraging signs that the analyses of these parameters in the separate phases of the ETUG procedure offer the potential for improved discrimination between frail and non-frail individuals. However, further in-depth study is required to verify the findings. PMID:26245213

  4. Fabrication and laser patterning of polystyrene optical oxygen sensor films for lab-on-a-chip applications.

    PubMed

    Grist, S M; Oyunerdene, N; Flueckiger, J; Kim, J; Wong, P C; Chrostowski, L; Cheung, K C

    2014-11-21

    We present a novel and simple method for patterning oxygen-sensitive polystyrene thin films and demonstrate its potential for integration with microfluidic lab-on-a-chip devices. Optical oxygen sensing films composed of polystyrene with an embedded luminescent oxygen-sensitive dye present a convenient option for the measurement of oxygen levels in microfluidic and lab-on-a-chip devices; however, patterning and integrating the films with poly(dimethylsiloxane) (PDMS) microfluidic devices has proven difficult due to a residue after dry etch patterning that inhibits subsequent PDMS bonding. Our new method uses mask-less laser ablation by a commercial laser ablation system to define the outline of the structures and subsequent bulk film removal by aqueous lift-off. Because the bulk film is peeled or lifted off of the substrate rather than etched, the process is compatible with standard PDMS plasma bonding. We used ToF-SIMS analysis to investigate how laser ablation facilitates this fabrication process as well as why dry etching polystyrene inhibits PDMS plasma bonding. The results of this analysis showed evidence of chemical species formed during the laser ablation and dry etching processes that can produce these effects. Our new method's mask-less nature, simplicity, speed, and compatibility with PDMS bonding make it ideally suited for single-use lab-on-a-chip applications. To demonstrate the method's compatibility with PDMS microfluidics, we also present a demonstration of the sensors' integration into a microfluidic oxygen gradient generator device. PMID:25230092

  5. Experimental Assessment of the Quanergy m8 LIDAR Sensor

    NASA Astrophysics Data System (ADS)

    Mitteta, M.-A.; Nouira, H.; Roynard, X.; Goulette, F.; Deschaud, J.-E.

    2016-06-01

    In this paper, some experiments with the Quanergy M8 scanning LIDAR system are related. The distance measurement obtained with the Quanergy M8 can be influenced by different factors. Moreover, measurement errors can originate from different sources. The environment in which the measurements are performed has an influence (temperature, light, humidity, etc.). Errors can also arise from the system itself. Then, it is necessary to determine the influence of these parameters on the quality of the distance measurements. For this purpose different studies are presented and analyzed. First, we studied the temporal stability of the sensor by analyzing observations during time. Secondly, the assessment of the distance measurement quality has been conducted. The aim of this step is to detect systematic errors in measurements regarding the range. Differents series of measurements have been conducted : at different range and in diffrent conditions (indoor and outdoor). Finally, we studied the consistency between the differents beam of the LIDAR.

  6. Benthic microbial fuel cell as direct power source for an acoustic modem and seawater oxygen/temperature sensor system.

    PubMed

    Gong, Yanming; Radachowsky, Sage E; Wolf, Michael; Nielsen, Mark E; Girguis, Peter R; Reimers, Clare E

    2011-06-01

    Supported by the natural potential difference between anoxic sediment and oxic seawater, benthic microbial fuel cells (BMFCs) promise to be ideal power sources for certain low-power marine sensors and communication devices. In this study a chambered BMFC with a 0.25 m(2) footprint was used to power an acoustic modem interfaced with an oceanographic sensor that measures dissolved oxygen and temperature. The experiment was conducted in Yaquina Bay, Oregon over 50 days. Several improvements were made in the BMFC design and power management system based on lessons learned from earlier prototypes. The energy was harvested by a dynamic gain charge pump circuit that maintains a desired point on the BMFC's power curve and stores the energy in a 200 F supercapacitor. The system also used an ultralow power microcontroller and quartz clock to read the oxygen/temperature sensor hourly, store data with a time stamp, and perform daily polarizations. Data records were transmitted to the surface by the acoustic modem every 1-5 days after receiving an acoustic prompt from a surface hydrophone. After jump-starting energy production with supplemental macroalgae placed in the BMFC's anode chamber, the average power density of the BMFC adjusted to 44 mW/m(2) of seafloor area which is better than past demonstrations at this site. The highest power density was 158 mW/m(2), and the useful energy produced and stored was ≥ 1.7 times the energy required to operate the system. PMID:21545151

  7. An integrated laser Raman optical sensor for fast detection of nitrogen and oxygen in a cryogenic mixture.

    PubMed

    Tiwari, Vidhu S; Luanje, Appolinaire T; Kalluru, Rajamohan R; Yueh, Fang Y; Singh, Jagdish P

    2011-04-01

    An integrated fiber optic Raman sensor was designed for real-time, nonintrusive detection of liquid nitrogen (LN(2)) in liquid oxygen (LO(2)) at high pressures and high flow rates. This was intended to monitor the quality of LO(2) in oxidizer feed lines during the ground testing of rocket engines. Various issues related to optical diagnosis of cryogenic fluids (LN(2)/LO(2)) in supercritical environment of rocket engine test facility, such as fluorescence from impurity in optical window of feed line, signal-noise ratio, and fast data acquisition time, etc., are well addressed. The integrated sensor employed a frequency doubled 532-nm continuous wave Nd:YAG laser as an excitation light source. The other optical components included were InPhotonics Raman probes, spectrometers, and photomultiplier tubes (PMTs). The spectrometer was used to collect the Raman spectrum of LN(2) and LO(2). The PMT detection unit was integrated with home-built LABVIEW software for fast monitoring of concentration ratios LN(2) and LO(2). Prior to designing an integrated sensor system, its optical components were also tested with gaseous nitrogen (GN(2)) and oxygen (GO(2)). PMID:21528996

  8. Wearable Sensor-Based Rehabilitation Exercise Assessment for Knee Osteoarthritis

    PubMed Central

    Chen, Kun-Hui; Chen, Po-Chao; Liu, Kai-Chun; Chan, Chia-Tai

    2015-01-01

    Since the knee joint bears the full weight load of the human body and the highest pressure loads while providing flexible movement, it is the body part most vulnerable and susceptible to osteoarthritis. In exercise therapy, the early rehabilitation stages last for approximately six weeks, during which the patient works with the physical therapist several times each week. The patient is afterwards given instructions for continuing rehabilitation exercise by him/herself at home. This study develops a rehabilitation exercise assessment mechanism using three wearable sensors mounted on the chest, thigh and shank of the working leg in order to enable the patients with knee osteoarthritis to manage their own rehabilitation progress. In this work, time-domain, frequency-domain features and angle information of the motion sensor signals are used to classify the exercise type and identify whether their postures are proper or not. Three types of rehabilitation exercise commonly prescribed to knee osteoarthritis patients are: Short-Arc Exercise, Straight Leg Raise, and Quadriceps Strengthening Mini-squats. After ten subjects performed the three kinds of rehabilitation activities, three validation techniques including 10-fold cross-validation, within subject cross validation, and leave-one-subject cross validation are utilized to confirm the proposed mechanism. The overall recognition accuracy for exercise type classification is 97.29% and for exercise posture identification it is 88.26%. The experimental results demonstrate the feasibility of the proposed mechanism which can help patients perform rehabilitation movements and progress effectively. Moreover, the proposed mechanism is able to detect multiple errors at once, fulfilling the requirements for rehabilitation assessment. PMID:25686308

  9. Using soil oxygen sensors to inform understanding of soil greenhouse gas dynamics

    NASA Astrophysics Data System (ADS)

    Jarecke, K. M.; Loecke, T.; Burgin, A. J.; Franz, T. E.; Rubol, S.

    2015-12-01

    Hot spots and hot moments of greenhouse gas (GHG) fluxes can contribute significantly to overall GHG budgets. Hot spots and hot moments occur when dynamic soil hydrology triggers important shifts in soil biogeochemical and physical processes that control GHG emissions. Soil oxygen (O2), a direct control on biogenic GHG production (i.e., nitrous oxide-N2O, carbon dioxide-CO2 and methane-CH4), may serve as both an important proxy for determining sudden shifts in subsurface biogenic GHG production, as well as the physical transport of soil GHG to the atmosphere. Recent technological advancements offer opportunities to link in-situ, near-continuous measurements of soil O2 concentration to soil biogeochemical processes and soil gas transport. Using high frequency data, this study asked: Do soil O2 dynamics correspond to changes in soil GHG concentrations and GHG surface fluxes? We addressed this question using precipitation event-based and weekly sampling (19 months in duration) data sets from a restored riparian wetland in Ohio, USA. During and after precipitation events, changes in subsurface (10 and 20 cm) CO2 and N2O concentrations were inversely related to short-term (< 48 h) changes in soil O2 concentrations. Subsurface CH4 concentrations changes during precipitation events, however, did not change in response to soil O2 dynamics. Changing subsurface GHG concentrations did not necessarily translate into altered surface (soil to atmosphere) GHG fluxes; soil O2 dynamics at 10 cm did not correspond with changes in surface N2O and CH4 fluxes. However, changes in soil O2 concentration at 10 cm had a significant positive linear relationship with change in surface CO2­ flux. We used a random forest approach to identify the soil sensor data (O2, temperature, moisture) which contribute the most to predicting weekly GHG fluxes. Our study suggests that monitoring near-continuous soil O2 concentration under dynamic soil hydrology may lead to greater understanding of GHG

  10. Methodology for the assessment of oxygen as an energy carrier

    NASA Astrophysics Data System (ADS)

    Yang, Ming Wei

    Due to the energy intensity of the oxygen generating process, the electric power grid would benefit if the oxygen generating process was consumed electric power only during low demand periods. Thus, the question to be addressed in this study is whether oxygen production and/or usage can be modified to achieve energy storage and/or transmission objectives at lower cost. The specific benefit to grid would be a leveling, over time, of the demand profile and thus would require less installation capacity. In order to track the availability of electricity, a compressed air storage unit is installed between the cryogenic distillation section and the main air compressor of air separation unit. A profit maximizing scheme for sizing storage inventory and related equipments is developed. The optimum scheme is capable of market responsiveness. Profits of steel maker, oxy-combustion, and IGCC plants with storage facilities can be higher than those plants without storage facilities, especially, at high-price market. Price tracking feature of air storage integration will certainly increase profit margins of the plants. The integration may push oxy-combustion and integrated gasification combined cycle process into economic viability. Since oxygen is used in consumer sites, it may generate at remote locations and transport to the place needed. Energy losses and costs analysis of oxygen transportation is conducted for various applications. Energy consumptions of large capacity and long distance GOX and LOX pipelines are lower than small capacity pipelines. However, transportation losses and costs of GOX and LOX pipelines are still higher than electricity transmission.

  11. 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

  12. Designing a Microfluidic Device with Integrated Ratiometric Oxygen Sensors for the Long-Term Control and Monitoring of Chronic and Cyclic Hypoxia.

    PubMed

    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

  13. The Heme-Based Oxygen-Sensor Phosphodiesterase Ec DOS (DosP): Structure-Function Relationships

    PubMed Central

    Shimizu, Toru

    2013-01-01

    Escherichia coli Direct Oxygen Sensor (Ec DOS, also known as Ec DosP) is a heme-based O2-sensing phosphodiesterase from Escherichia coli that catalyzes the conversion of cyclic-di-GMP to linear di-GMP. Cyclic-di-GMP is an important second messenger in bacteria, highlighting the importance of understanding structure-function relationships of Ec DOS. Ec DOS is composed of an N-terminal heme-bound O2-sensing PAS domain and a C-terminal phosphodiesterase catalytic domain. Notably, its activity is markedly enhanced by O2 binding to the heme Fe(II) complex in the PAS sensor domain. X-ray crystal structures and spectroscopic and catalytic characterization of the wild-type and mutant proteins have provided important structural and functional clues to understanding the molecular mechanism of intramolecular catalytic regulation by O2 binding. This review summarizes the intriguing findings that have obtained for Ec DOS. PMID:25586128

  14. A Micro Oxygen Sensor Based on a Nano Sol-Gel TiO2 Thin Film

    PubMed Central

    Wang, Hairong; Chen, Lei; Wang, Jiaxin; Sun, Quantao; Zhao, Yulong

    2014-01-01

    An oxygen gas microsensor based on nanostructured sol-gel TiO2 thin films with a buried Pd layer was developed on a silicon substrate. The nanostructured titania thin films for O2 sensors were prepared by the sol-gel process and became anatase after heat treatment. A sandwich TiO2 square board with an area of 350 μm × 350 μm was defined by both wet etching and dry etching processes and the wet one was applied in the final process due to its advantages of easy control for the final structure. A pair of 150 nm Pt micro interdigitated electrodes with 50 nm Ti buffer layer was fabricated on the board by a lift-off process. The sensor chip was tested in a furnace with changing the O2 concentration from 1.0% to 20% by monitoring its electrical resistance. Results showed that after several testing cycles the sensor's output becomes stable, and its sensitivity is 0.054 with deviation 2.65 × 10−4 and hysteresis is 8.5%. Due to its simple fabrication process, the sensor has potential for application in environmental monitoring, where lower power consumption and small size are required. PMID:25192312

  15. Bladder urine oxygen tension for assessing renal medullary oxygenation in rabbits: experimental and modeling studies.

    PubMed

    Sgouralis, Ioannis; Kett, Michelle M; Ow, Connie P C; Abdelkader, Amany; Layton, Anita T; Gardiner, Bruce S; Smith, David W; Lankadeva, Yugeesh R; Evans, Roger G

    2016-09-01

    Oxygen tension (Po2) of urine in the bladder could be used to monitor risk of acute kidney injury if it varies with medullary Po2 Therefore, we examined this relationship and characterized oxygen diffusion across walls of the ureter and bladder in anesthetized rabbits. A computational model was then developed to predict medullary Po2 from bladder urine Po2 Both intravenous infusion of [Phe(2),Ile(3),Orn(8)]-vasopressin and infusion of N(G)-nitro-l-arginine reduced urinary Po2 and medullary Po2 (8-17%), yet had opposite effects on renal blood flow and urine flow. Changes in bladder urine Po2 during these stimuli correlated strongly with changes in medullary Po2 (within-rabbit r(2) = 0.87-0.90). Differences in the Po2 of saline infused into the ureter close to the kidney could be detected in the bladder, although this was diminished at lesser ureteric flow. Diffusion of oxygen across the wall of the bladder was very slow, so it was not considered in the computational model. The model predicts Po2 in the pelvic ureter (presumed to reflect medullary Po2) from known values of bladder urine Po2, urine flow, and arterial Po2 Simulations suggest that, across a physiological range of urine flow in anesthetized rabbits (0.1-0.5 ml/min for a single kidney), a change in bladder urine Po2 explains 10-50% of the change in pelvic urine/medullary Po2 Thus, it is possible to infer changes in medullary Po2 from changes in urinary Po2, so urinary Po2 may have utility as a real-time biomarker of risk of acute kidney injury. PMID:27385734

  16. Monitoring the impact of pressure on the assessment of skin perfusion and oxygenation using a novel pressure device

    NASA Astrophysics Data System (ADS)

    Ramella-Roman, Jessica C.; Ho, Thuan; Le, Du; Ghassemi, Pejhman; Nguyen, Thu; Lichy, Alison; Groah, Suzanne

    2013-03-01

    Skin perfusion and oxygenation is easily disrupted by imposed pressure. Fiber optics probes, particularly those spectroscopy or Doppler based, may relay misleading information about tissue microcirculation dynamics depending on external forces on the sensor. Such forces could be caused by something as simple as tape used to secure the fiber probe to the test subject, or as in our studies by the full weight of a patient with spinal cord injury (SCI) sitting on the probe. We are conducting a study on patients with SCI conducting pressure relief maneuvers in their wheelchairs. This study aims to provide experimental evidence of the optimal timing between pressure relief maneuvers. We have devised a wireless pressure-controlling device; a pressure sensor positioned on a compression aluminum plate reads the imposed pressure in real time and sends the information to a feedback system controlling two position actuators. The actuators move accordingly to maintain a preset value of pressure onto the sample. This apparatus was used to monitor the effect of increasing values of pressure on spectroscopic fiber probes built to monitor tissue oxygenation and Doppler probes used to assess tissue perfusion.

  17. Measurement in a marine environment using low cost sensors of temperature and dissolved oxygen

    USGS Publications Warehouse

    Godshall, F.A.; Cory, R.L.; Phinney, D.E.

    1974-01-01

    Continuous records of physical parameters of the marine environment are difficult as well as expensive to obtain. This paper describes preliminary results of an investigative program with the purpose of developing low cost time integrating measurement and averaging devices for water temperature and dissolved oxygen. Measurements were made in an estuarine area of the Chesapeake Bay over two week periods. With chemical thermometers average water temperature for the two week period was found to be equal to average water temperature measured with thermocouples plus or minus 1.0 C. The slow diffusion of oxygen through the semipermiable sides of plastic bottles permitted the use of water filled bottles to obtain averaged oxygen measurements. Oxygen measurements for two week averaging times using 500 ml polyethylene bottles were found to vary from conventionally measured and averaged dissolved oxygen by about 1.8 mg/l. ?? 1974 Estuarine Research Federation.

  18. Sm3+ doped TiO2 as optical oxygen sensor material

    NASA Astrophysics Data System (ADS)

    Eltermann, Marko; Utt, Kathriin; Lange, Sven; Jaaniso, Raivo

    2016-01-01

    The luminescence properties of Sm3+ in sol-gel-made nanostructural TiO2 were shown to depend on surrounding gas environment. Both the intensity and lifetime of the luminescence increased with increasing oxygen content varied between 0% and 100% in the O2/N2 mixture at normal pressure. The luminescence decay kinetics after pulsed excitation at 355 nm followed the stretched exponential function with the value of stretching exponent equal to 0.4-0.5. The mechanism of oxygen sensitivity was interpreted as resonant excitation energy transfer from Sm3+ to the acceptor defects, the latter being switched on and off the resonance by electron exchange with surface-adsorbed oxygen. Oxygen vacancy related defects were proposed as most likely candidates of energy acceptors. The studied material can be used for luminescence lifetime based oxygen sensing.

  19. Oxygenation in cervical cancer and normal uterine cervix assessed using blood oxygenation level-dependent (BOLD) MRI at 3T.

    PubMed

    Hallac, Rami R; Ding, Yao; Yuan, Qing; McColl, Roderick W; Lea, Jayanthi; Sims, Robert D; Weatherall, Paul T; Mason, Ralph P

    2012-12-01

    Hypoxia is reported to be a biomarker for poor prognosis in cervical cancer. However, a practical noninvasive method is needed for the routine clinical evaluation of tumor hypoxia. This study examined the potential use of blood oxygenation level-dependent (BOLD) contrast MRI as a noninvasive technique to assess tumor vascular oxygenation at 3T. Following Institutional Review Board-approved informed consent and in compliance with the Health Insurance Portability and Accountability Act, successful results were achieved in nine patients with locally advanced cervical cancer [International Federation of Gynecology and Obstetrics (FIGO) stage IIA to IVA] and three normal volunteers. In the first four patients, dynamic T₂*-weighted MRI was performed in the transaxial plane using a multi-shot echo planar imaging sequence whilst patients breathed room air followed by oxygen (15 dm³/min). Later, a multi-echo gradient echo examination was added to provide quantitative R₂* measurements. The baseline T₂*-weighted signal intensity was quite stable, but increased to various extents in tumors on initiation of oxygen breathing. The signal in normal uterus increased significantly, whereas that in the iliacus muscle did not change. R₂* responded significantly in healthy uterus, cervix and eight cervical tumors. This preliminary study demonstrates that BOLD MRI of cervical cancer at 3T is feasible. However, more patients must be evaluated and followed clinically before any prognostic value can be determined. PMID:22619091

  20. Photoacoustic assessment of oxygen saturation: effect of red blood cell aggregation

    NASA Astrophysics Data System (ADS)

    Hysi, Eno; Saha, Ratan K.; Kolios, Michael C.

    2013-03-01

    The simultaneous photoacoustic assessment of oxygen saturation and red blood cell aggregation is presented. Aggregation was induced on porcine red blood cells using Dextran-70 at multiple hematocrit levels. Samples were exposed to 750 nm and 1064 nm for each hematocrit and aggregate size in order to compute the oxygen saturation. As the size of the aggregate increased, the photoacoustic signal amplitude increased monotonically. The same trend was observed for increasing hematocrit at each aggregation level. The oxygen saturation of aggregated samples was 30% higher than non-aggregated samples at each hematocrit level. This suggests that the presence of red blood cell aggregates impairs the release of oxygen to the surrounding environment. Such a result has important implications for detecting red blood cell aggregation non-invasively and making clinical decisions based on the simulatenous assessment of oxygen saturation.

  1. Effect of depletion layer width on electrical properties of semiconductive thin film gas sensor: a numerical study based on the gradient-distributed oxygen vacancy model

    NASA Astrophysics Data System (ADS)

    Liu, Jianqiao; Lu, Yiting; Cui, Xiao; Jin, Guohua; Zhai, Zhaoxia

    2016-03-01

    The effects of depletion layer width on the semiconductor gas sensors were investigated based on the gradient-distributed oxygen vacancy model, which provided numerical descriptions for the sensor properties. The potential barrier height, sensor resistance, and response to target gases were simulated to reveal their dependences on the depletion layer width. According to the simulation, it was possible to improve the sensor response by enlarging the width of depletion layer without changing the resistance of the gas sensor under the special circumstance. The different performances between resistance and response could provide a bright expectation that the design and fabrication of gas sensing devices could be economized. The simulation results were validated by the experimental performances of SnO2 thin film gas sensors, which were prepared by the sol-gel technique. The dependences of sensor properties on depletion layer width were observed to be in agreement with the simulations.

  2. Dynamic component chemiluminescent sensor for assessing circulating polymorphonuclear leukocyte activity of peritoneal dialysis patients.

    PubMed

    Prilutsky, Daria; Rogachev, Boris; Vorobiov, Marina; Zlotnik, Moshe; Last, Mark; Lobel, Leslie; Marks, Robert S

    2008-07-01

    Recurrent bacterial peritonitis is a major complication in peritoneal dialysis (PD) patients, which is associated with polymorphonuclear leukocyte (PMN) functional changes and can be assessed by a chemiluminescent (CL) reaction. We applied a new approach of a dynamic component chemiluminescence sensor for the assessment of functional states of PMNs in a luminol-amplified whole-blood system. This method is based on the evaluation of CL kinetic patterns of stimulated PMNs, while the parallel measurements of intracellular and extracellular production of reactive oxygen species (ROS) from the same sample can be conducted. Blood was drawn from diabetic and nondiabetic patients during follow-up, and during peritonitis. Healthy medical personnel served as the control group. Chemiluminescence curves were recorded and presented as a sum of three biological components. CL kinetic parameters were calculated, and functional states of PMNs were assessed. Data mining algorithms were used to build decision tree models that can distinguish between different clinical groups. The induced classification models were used afterward for differentiating and classifying new blind cases and demonstrated good correlation with medical diagnosis (84.6% predictive accuracy). In conclusion, this novel method shows a high predictive diagnostic value and may assist in detection of PD-associated clinical states. PMID:18510343

  3. Transition metal substituted SrTiO3 perovskite oxides as promising functional materials for oxygen sensor

    NASA Astrophysics Data System (ADS)

    Misra, Sunasira

    2012-07-01

    Modern industries employ several gases as process fluids. Leakage of these gases in the operating area could lead to undesirable consequences. Even in chemical industries, which use large quantities of inert gases in confined areas, accidental leakage of these process gases would result in the reduction of oxygen partial pressure in atmospheric air. For instance, large amounts of gaseous nitrogen and argon are used in pharmaceutical industries, gas filling/bottling plants, operating area of Fast Breeder reactors, etc. Fall of concentration of oxygen in air below 17% could lead to life risk (Asphyxiation) of the working personnel that has to be checked well in advance. Further, when the leaking gas is of explosive nature, its damage potential would be very high if its concentration level in air increases beyond its lower explosive limit. Surveillance of the ambient within these industries at the critical areas and also in the environment around them for oxygen therefore becomes highly essential. Sensitive and selective gas sensors made of advanced materials are required to meet this demand of monitoring environmental pollution. The perovskite class of oxides (ABO3) is chemically stable even at high temperatures and can tolerate large levels of dopants without phase transformations. The electronic properties of this parent functional material can be tailored by adding appropriate dopants that exhibit different valence states. Aliovalent transition metal substituted SrTiO3 perovskites are good mixed ionic and electronic conductors and potential candidates for sensing oxygen at percentage level exploiting their oxygen pressure dependent electrical conductivity. This paper presents the preparation, study of electrical conductivity and oxygen-sensing characteristics of iron and cobalt substituted SrTiO3.

  4. Method of assessing blood oxygenation in microcirculation vessels based on Doppler approach

    NASA Astrophysics Data System (ADS)

    Sokolov, Vladimir G.; Korsi, Larissa V.; Egorov, Sergei Y.

    2001-06-01

    Combination of laser Doppler flowmetry and pulse oximetry methods allows for the direct assessment of oxygen supply to tissues at the microcirculatory level, namely, in that part of the vascular network where the transcapillary exchange takes place that is responsible for saturating tissues with oxygen. The microcirculation system comprises arterial and venous microvascular parts that differ in blood flow velocities. Frequency separation of the photodetector signal components related to different velocity ranges makes possible to distinguish the hemodynamic processes in these two parts of the microvascular system. Moreover, numerous studies of collective oscillatory processes in hemodynamics reveal that cardio-oscillations are more pronounced in arterioles, whereas venous hemodynamics is mostly influenced by the breath rhythm. Taking account of the above phenomena allows developing a signal-filtration system for separate characterization of blood-oxygenation states in arterial and venous blood flows. Light absorbance in the skin depends on both light wavelength and blood-oxygenation level. Processing the signals obtained with a two-channel dual-wavelength (630 and 1115 nm) laser Doppler flowmeter provides information about blood oxygenation levels at the entrance and exit of the microvascular system and allows assessing the specific levels of oxygenation levels at the entrance and exit of the microvascular system and allows assessing the specific levels of oxygen consumption in tissues. In particular, this approach allows revealing pathogenic processes resulting from hyper- and hypo-oxygenation in tissues. For instance, rapidly growing malignant tumors are characterized by intensive metabolism, rapid formation of capillaries, and active transcapillary oxygen exchange that results in higher level of oxygen diffusion into tissue, while the level of oxygen is lowered in the microvascular veins.

  5. Multiple approaches for enhancing all-organic electronics photoluminescent sensors: simultaneous oxygen and pH monitoring.

    PubMed

    Liu, Rui; Xiao, Teng; Cui, Weipan; Shinar, Joseph; Shinar, Ruth

    2013-05-17

    Key issues in using organic light emitting diodes (OLEDs) as excitation sources in structurally integrated photoluminescence (PL)-based sensors are the low forward light outcoupling, the OLEDs' broad electroluminescence (EL) bands, and the long-lived remnant EL that follows an EL pulse. The outcoupling issue limits the detection sensitivity (S) as only ~20% of the light generated within standard OLEDs can be forward outcoupled and used for sensor probe excitation. The EL broad band interferes with the analyte-sensitive PL, leading to a background that reduces S and dynamic range. In particular, these issues hinder designing compact sensors, potentially miniaturizable, that are devoid of optical filters and couplers. We address these shortcomings by introducing easy-to-employ multiple approaches for outcoupling improvement, PL enhancement, and background EL reduction leading to novel, compact all-organic device architectures demonstrated for simultaneous monitoring of oxygen and pH. The sensor comprises simply-fabricated, directionally-emitting, narrower-band, multicolor microcavity OLED excitation and small molecule- and polymer-based organic photodetectors (OPDs) with a more selective spectral response. Additionally, S and PL intensity for oxygen are enhanced by using polystyrene (PS):polyethylene glycol (PEG) blends as the sensing film matrix. By utilizing higher molecular weight PS, the ratio τ0/τ100 (PL decay time τ at 0% O2/τ at 100% O2) that is often used to express S increases ×1.9 to 20.7 relative to the lower molecular weight PS, where this ratio is 11.0. This increase reduces to ×1.7 when the PEG is added (τ0/τ100=18.2), but the latter results in an increase ×2.7 in the PL intensity. The sensor's response time is <10s in all cases. The microporous structure of these blended films, with PEG decorating PS pores, serves a dual purpose. It results in light scattering that reduces the EL that is waveguided in the substrate of the OLEDs and

  6. Skeletal Muscle Oxygenation Measured by EPR Oximetry Using a Highly Sensitive Polymer-Encapsulated Paramagnetic Sensor.

    PubMed

    Hou, H; Khan, N; Nagane, M; Gohain, S; Chen, E Y; Jarvis, L A; Schaner, P E; Williams, B B; Flood, A B; Swartz, H M; Kuppusamy, P

    2016-01-01

    We have incorporated LiNc-BuO, an oxygen-sensing paramagnetic material, in polydimethylsiloxane (PDMS), which is an oxygen-permeable, biocompatible, and stable polymer. We fabricated implantable and retrievable oxygen-sensing chips (40 % LiNc-BuO in PDMS) using a 20-G Teflon tubing to mold the chips into variable shapes and sizes for in vivo studies in rats. In vitro EPR measurements were used to test the chip's oxygen response. Oxygen induced linear and reproducible line broadening with increasing partial pressure (pO2). The oxygen response was similar to that of bare (unencapsulated) crystals and did not change significantly on sterilization by autoclaving. The chips were implanted in rat femoris muscle and EPR oximetry was performed repeatedly (weekly) for 12 weeks post-implantation. The measurements showed good reliability and reproducibility over the period of testing. These results demonstrated that the new formulation of OxyChip with 40 % LiNc-BuO will enable the applicability of EPR oximetry for long-term measurement of oxygen concentration in tissues and has the potential for clinical applications. PMID:27526163

  7. Age dependency of cerebral oxygenation assessed with near infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Colier, Willy N.; van Haaren, Nicole J.; van de Ven, Marjo J.; Folgering, Hans T.; Oeseburg, Berend

    1997-04-01

    Near-IR spectroscopy (NIRS) is an optical technique that provides information on cerebral tissue oxygenation and hemodynamics on a continuous, direct, and noninvasive basis. It is used to determine cerebral blood volume (CBV) and cerebrovascular CO2 reactivity during normoxic hyper- and hypocapnia in a group of 28 healthy volunteers aged 20 to 83 years. The main focus is on to the age dependency of the measured variables. The influence of changes in minute ventilation during normocapnia on the cerebral oxygenation was also studied. The mean CBV in age was, for 20 to 30 years, 2.14 +/- 0.51 ml/100 g of brain tissue; for 45 to 50 years, 1.92 +/- 0.40 ml/100 g; and for 70 to 83 years, 1.47 +/- 0.55 ml/100 g. The CBV showed a significant decease with advancing age. No influence was found for a change in minute ventilation on cerebral oxygenation. During hypercapnia cerebral blood flow (CBF) significantly increased in al age groups, with a factor of 1.31 +/- 0.17 kPa-1, 1.64 +/- 1.39 kPa-1, and 2.4 +/- 1.7 kPa-1, respectively, for the three age groups. The difference in change among the age groups was not statistically significant. The trend seen was an increased change in CBF with advancing age. During hypocapnia, the CBF significantly decreased in all age groups, with a factor of 0.89 +/- 0.08 kPa-1, 0.89 +/- 0.04 kPa-1, and 0.85 +/- 0.11 kPa-1, respectively. There was no significant difference among the age groups.

  8. In situ measurement of atomic oxygen flux using a silver film sensor onboard "TianTuo 1" nanosatellite

    NASA Astrophysics Data System (ADS)

    Cheng, Yun; Chen, Xiaoqian; Sheng, Tao

    2016-01-01

    Research into the measurement of atomic oxygen (AO) flux in a low Earth orbit (LEO) is highly significant for the development of spacecraft surface materials as well as for enhancing the reliability of space instruments. In the present study, we studied a silver film resistance method for AO flux measurement and we established a quantitative calculation model. Moreover, we designed a silver film sensor for space flight tests with a mass of about 100 g and a peak power consumption of less than 0.2 W. The effect of AO on the silver film was demonstrated in a ground-based simulation experiment and compared with the Kapton-mass-loss method. For the space flight test, the AO flux was estimated by monitoring the change in the resistance in the linear part of the silver/AO reaction regime. Finally, the sensor was carried onboard our nanosatellite "TianTuo 1" to obtain in situ measurements of the AO flux during a 476 km sun synchronous orbit. The result was critically compared with theoretical predictions, which validated the design of this sensor.

  9. Spatial interpolation quality assessments for soil sensor transect datasets

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Near-ground geophysical soil sensors provide extremely valuable information for precision agriculture applications. Indeed, their readings can be used as proxy for many soil parameters. Typically, leave-one-out (loo) cross-validation (CV) of spatial interpolation of sensor data returns overly optimi...

  10. Oxygenation of the calf muscle during an incremental, intermittent walking exercise assessed by NIRS

    NASA Astrophysics Data System (ADS)

    Härtel, S.; Kutzner, C.; Schneider, D.; Grieger, S.; Neumaier, M.; Kohl-Bareis, M.

    2011-07-01

    We use near infrared spectroscopy (NIRS) for the non-invasive assessment of calf oxygenation during a new walking protocol in healthy subjects of different fitness levels. The protocol increases the exercise power by an increase of the skew rather than speed, and the incremental power steps are intermitted by a 30 s rest which serves for blood sampling. The NIRS measurement parameter of tissue oxygenation are discussed, and a high correlation of the oxygen saturation (tissue oxygenation index) difference between exercise and rest period with exercise power is observed. This difference parameter can be interpreted as strongly linked to blood flow rather than oxygenation. This finding is supported by comparison with spirometry data. The effect of training is discussed. The exercise protocol is suited for testing unfit, or older subjects and the data discussed here servers as a test for a larger trial with heart clinic patients.

  11. Validation and assessment of integer programming sensor placement models.

    SciTech Connect

    Uber, James G.; Hart, William Eugene; Watson, Jean-Paul; Phillips, Cynthia Ann; Berry, Jonathan W.

    2005-02-01

    We consider the accuracy of predictions made by integer programming (IP) models of sensor placement for water security applications. We have recently shown that IP models can be used to find optimal sensor placements for a variety of different performance criteria (e.g. minimize health impacts and minimize time to detection). However, these models make a variety of simplifying assumptions that might bias the final solution. We show that our IP modeling assumptions are similar to models developed for other sensor placement methodologies, and thus IP models should give similar predictions. However, this discussion highlights that there are significant differences in how temporal effects are modeled for sensor placement. We describe how these modeling assumptions can impact sensor placements.

  12. Estimating Orientation Using Magnetic and Inertial Sensors and Different Sensor Fusion Approaches: Accuracy Assessment in Manual and Locomotion Tasks

    PubMed Central

    Bergamini, Elena; Ligorio, Gabriele; Summa, Aurora; Vannozzi, Giuseppe; Cappozzo, Aurelio; Sabatini, Angelo Maria

    2014-01-01

    Magnetic and inertial measurement units are an emerging technology to obtain 3D orientation of body segments in human movement analysis. In this respect, sensor fusion is used to limit the drift errors resulting from the gyroscope data integration by exploiting accelerometer and magnetic aiding sensors. The present study aims at investigating the effectiveness of sensor fusion methods under different experimental conditions. Manual and locomotion tasks, differing in time duration, measurement volume, presence/absence of static phases, and out-of-plane movements, were performed by six subjects, and recorded by one unit located on the forearm or the lower trunk, respectively. Two sensor fusion methods, representative of the stochastic (Extended Kalman Filter) and complementary (Non-linear observer) filtering, were selected, and their accuracy was assessed in terms of attitude (pitch and roll angles) and heading (yaw angle) errors using stereophotogrammetric data as a reference. The sensor fusion approaches provided significantly more accurate results than gyroscope data integration. Accuracy improved mostly for heading and when the movement exhibited stationary phases, evenly distributed 3D rotations, it occurred in a small volume, and its duration was greater than approximately 20 s. These results were independent from the specific sensor fusion method used. Practice guidelines for improving the outcome accuracy are provided. PMID:25302810

  13. Estimating orientation using magnetic and inertial sensors and different sensor fusion approaches: accuracy assessment in manual and locomotion tasks.

    PubMed

    Bergamini, Elena; Ligorio, Gabriele; Summa, Aurora; Vannozzi, Giuseppe; Cappozzo, Aurelio; Sabatini, Angelo Maria

    2014-01-01

    Magnetic and inertial measurement units are an emerging technology to obtain 3D orientation of body segments in human movement analysis. In this respect, sensor fusion is used to limit the drift errors resulting from the gyroscope data integration by exploiting accelerometer and magnetic aiding sensors. The present study aims at investigating the effectiveness of sensor fusion methods under different experimental conditions. Manual and locomotion tasks, differing in time duration, measurement volume, presence/absence of static phases, and out-of-plane movements, were performed by six subjects, and recorded by one unit located on the forearm or the lower trunk, respectively. Two sensor fusion methods, representative of the stochastic (Extended Kalman Filter) and complementary (Non-linear observer) filtering, were selected, and their accuracy was assessed in terms of attitude (pitch and roll angles) and heading (yaw angle) errors using stereophotogrammetric data as a reference. The sensor fusion approaches provided significantly more accurate results than gyroscope data integration. Accuracy improved mostly for heading and when the movement exhibited stationary phases, evenly distributed 3D rotations, it occurred in a small volume, and its duration was greater than approximately 20 s. These results were independent from the specific sensor fusion method used. Practice guidelines for improving the outcome accuracy are provided. PMID:25302810

  14. Parylene MEMS patency sensor for assessment of hydrocephalus shunt obstruction.

    PubMed

    Kim, Brian J; Jin, Willa; Baldwin, Alexander; Yu, Lawrence; Christian, Eisha; Krieger, Mark D; McComb, J Gordon; Meng, Ellis

    2016-10-01

    Neurosurgical ventricular shunts inserted to treat hydrocephalus experience a cumulative failure rate of 80 % over 12 years; obstruction is responsible for most failures with a majority occurring at the proximal catheter. Current diagnosis of shunt malfunction is imprecise and involves neuroimaging studies and shunt tapping, an invasive measurement of intracranial pressure and shunt patency. These patients often present emergently and a delay in care has dire consequences. A microelectromechanical systems (MEMS) patency sensor was developed to enable direct and quantitative tracking of shunt patency in order to detect proximal shunt occlusion prior to the development of clinical symptoms thereby avoiding delays in treatment. The sensor was fabricated on a flexible polymer substrate to eventually allow integration into a shunt. In this study, the sensor was packaged for use with external ventricular drainage systems for clinical validation. Insights into the transduction mechanism of the sensor were obtained. The impact of electrode size, clinically relevant temperatures and flows, and hydrogen peroxide (H2O2) plasma sterilization on sensor function were evaluated. Sensor performance in the presence of static and dynamic obstruction was demonstrated using 3 different models of obstruction. Electrode size was found to have a minimal effect on sensor performance and increased temperature and flow resulted in a slight decrease in the baseline impedance due to an increase in ionic mobility. However, sensor response did not vary within clinically relevant temperature and flow ranges. H2O2 plasma sterilization also had no effect on sensor performance. This low power and simple format sensor was developed with the intention of future integration into shunts for wireless monitoring of shunt state and more importantly, a more accurate and timely diagnosis of shunt failure. PMID:27589973

  15. Raman-based Oxygen and Nitrogen Sensor for Monitoring Empty Airplane Fuel Tanks

    NASA Technical Reports Server (NTRS)

    Chen, Peter C.

    2004-01-01

    The purpose of this project was to develop a Raman-based method for detecting oxygen and nitrogen in empty fuel tanks. The need for such a method comes from the potential danger of allowing explosive oxygen-fuel mixtures to accumulate in empty airplane fuel tanks. An explosion resulting from such a mixture is believed to have caused the Flight TWA 800 disaster in 1996. Recently, (e.g., February 17,2004 press release) the FAA announced its intentions to make fuel tank inerting mandatory. One potential solution to this problem is to use an inert gas such as nitrogen to flood the empty fue1 tanks in order to reduce the concentration of oxygen.

  16. A mitochondrial redox oxygen sensor in the pulmonary vasculature and ductus arteriosus.

    PubMed

    Dunham-Snary, Kimberly J; Hong, Zhigang G; Xiong, Ping Y; Del Paggio, Joseph C; Herr, Julia E; Johri, Amer M; Archer, Stephen L

    2016-01-01

    The mammalian homeostatic oxygen sensing system (HOSS) initiates changes in vascular tone, respiration, and neurosecretion that optimize oxygen uptake and tissue oxygen delivery within seconds of detecting altered environmental or arterial PO2. The HOSS includes carotid body type 1 cells, adrenomedullary cells, neuroepithelial bodies, and smooth muscle cells (SMCs) in pulmonary arteries (PAs), ductus arteriosus (DA), and fetoplacental arteries. Hypoxic pulmonary vasoconstriction (HPV) optimizes ventilation-perfusion matching. In utero, HPV diverts placentally oxygenated blood from the non-ventilated lung through the DA. At birth, increased alveolar and arterial oxygen tension dilates the pulmonary vasculature and constricts the DA, respectively, thereby transitioning the newborn to an air-breathing organism. Though modulated by endothelial-derived relaxing and constricting factors, O2 sensing is intrinsic to PASMCs and DASMCs. Within the SMC's dynamic mitochondrial network, changes in PO2 alter the reduction-oxidation state of redox couples (NAD(+)/NADH, NADP(+)/NADPH) and the production of reactive oxygen species, ROS (e.g., H2O2), by complexes I and III of the electron transport chain (ETC). ROS and redox couples regulate ion channels, transporters, and enzymes, changing intracellular calcium [Ca(2+)]i and calcium sensitivity and eliciting homeostatic responses to hypoxia. In PASMCs, hypoxia inhibits ROS production and reduces redox couples, thereby inhibiting O2-sensitive voltage-gated potassium (Kv) channels, depolarizing the plasma membrane, activating voltage-gated calcium channels (CaL), increasing [Ca(2+)]i, and causing vasoconstriction. In DASMCs, elevated PO2 causes mitochondrial fission, increasing ETC complex I activity and ROS production. The DASMC's downstream response to elevated PO2 (Kv channel inhibition, CaL activation, increased [Ca(2+)]i, and rho kinase activation) is similar to the PASMC's hypoxic response. Impaired O2 sensing contributes to

  17. Structural adaptation of microvessel diameters in response to metabolic stimuli: where are the oxygen sensors?

    PubMed

    Reglin, Bettina; Secomb, Timothy W; Pries, Axel R

    2009-12-01

    Maintenance of functional vascular networks requires structural adaptation of vessel diameters in response to hemodynamic and metabolic conditions. The mechanisms by which diameters respond to the metabolic state are not known, but may involve the release of vasoactive substances in response to low oxygen by tissue ("tissue signaling", e.g., CO2, adenosine), by vessel walls ("wall signaling", e.g., prostaglandins, adenosine), and/or by red blood cells (RBCs) ("RBC signaling", e.g., ATP and nitric oxide). Here, the goal was to test the potential of each of these locations of oxygen-dependent signaling to control steady-state vascular diameters and tissue oxygenation. A previously developed theoretical model of structural diameter adaptation based on experimental data on microvascular network morphology and hemodynamics was used. Resulting network characteristics were analyzed with regard to tissue oxygenation (Oxdef; percentage of tissue volume with PO2<1 Torr) and the difference between estimated blood flow velocities and corresponding experimental data [velocity error (Verr); root mean square deviation of estimated vs. measured velocity]. Wall signaling led to Oxdef<1% and to the closest hemodynamic similarity (Verr: 0.60). Tissue signaling also resulted in a low oxygen deficit, but a higher Verr (0.73) and systematic diameter deviations. RBC signaling led to widespread hypoxia (Oxdef: 4.7%), unrealistic velocity distributions (Verr: 0.81), and shrinkage of small vessels. The results suggest that wall signaling plays a central role in structural control of vessel diameters in microvascular networks of given angioarchitecture. Tissue-derived and RBC-derived signaling of oxygen levels may be more relevant for the regulation of angiogenesis and/or smooth muscle tone. PMID:19783778

  18. Structural adaptation of microvessel diameters in response to metabolic stimuli: where are the oxygen sensors?

    PubMed Central

    Reglin, Bettina; Secomb, Timothy W.

    2009-01-01

    Maintenance of functional vascular networks requires structural adaptation of vessel diameters in response to hemodynamic and metabolic conditions. The mechanisms by which diameters respond to the metabolic state are not known, but may involve the release of vasoactive substances in response to low oxygen by tissue (“tissue signaling”, e.g., CO2, adenosine), by vessel walls (“wall signaling”, e.g., prostaglandins, adenosine), and/or by red blood cells (RBCs) (“RBC signaling”, e.g., ATP and nitric oxide). Here, the goal was to test the potential of each of these locations of oxygen-dependent signaling to control steady-state vascular diameters and tissue oxygenation. A previously developed theoretical model of structural diameter adaptation based on experimental data on microvascular network morphology and hemodynamics was used. Resulting network characteristics were analyzed with regard to tissue oxygenation (Oxdef; percentage of tissue volume with Po2 < 1 Torr) and the difference between estimated blood flow velocities and corresponding experimental data [velocity error (Verr); root mean square deviation of estimated vs. measured velocity]. Wall signaling led to Oxdef < 1% and to the closest hemodynamic similarity (Verr: 0.60). Tissue signaling also resulted in a low oxygen deficit, but a higher Verr (0.73) and systematic diameter deviations. RBC signaling led to widespread hypoxia (Oxdef: 4.7%), unrealistic velocity distributions (Verr: 0.81), and shrinkage of small vessels. The results suggest that wall signaling plays a central role in structural control of vessel diameters in microvascular networks of given angioarchitecture. Tissue-derived and RBC-derived signaling of oxygen levels may be more relevant for the regulation of angiogenesis and/or smooth muscle tone. PMID:19783778

  19. Photoacoustic ultrasound spectroscopy for assessing red blood cell aggregation and oxygenation

    NASA Astrophysics Data System (ADS)

    Hysi, Eno; Saha, Ratan K.; Kolios, Michael C.

    2012-12-01

    Red blood cell (RBC) aggregation and oxygenation are important markers for a variety of blood disorders. No current technique is capable of simultaneously measuring aggregation/oxygenation levels noninvasively. We propose using photoacoustic ultrasound spectroscopy (PAUS) for assessing both phenomena. This technique relies on frequency-domain analysis of the PA signals by extracting parameters such as the ultrasound spectral slope and the midband fit. To investigate the effect of hematocrit, aggregation, and oxygenation levels on PAUS parameters, a Monte Carlo-based theoretical model and an experimental protocol using porcine RBCs were developed. The samples were illuminated at 750 and 1064 nm and changes in the PAUS parameters were compared to the oxygen-dependent optical absorption coefficients to assess the oxygenation level. Good agreement between the theoretical and experimental spectral parameters was obtained for the spectral slope of the nonaggregated spectra (˜0.3 dB/MHz). The experimental midband fit increased by ˜5 dB for the largest aggregate size. Based on the analysis of the PA signals, the oxygen saturation level of the most aggregated sample was >20% greater than the nonaggregated sample. The results provide a framework for using PA signals' spectroscopic parameters for monitoring the aggregation and oxygenation levels of RBCs.

  20. Assessment of global tissue perfusion and oxygenation in neonates and infants after open-heart surgery†

    PubMed Central

    Gergely, Mihály; Ablonczy, László; Székely, Edgár A.; Sápi, Erzsébet; Gál, János; Szatmári, András; Székely, Andrea

    2014-01-01

    OBJECTIVES Monitoring and preserving adequate perfusion and oxygen balance is a primary objective of critical care. This prospective observational study aimed to assess the relationship between global haemodynamic parameters and variables reflecting tissue oxygenation during the early period following corrective cardiac surgery in neonates and infants. The postoperative time course of oxygen delivery and consumption was evaluated. As surrogate markers of oxygen balance, the central venous oxygen saturation (ScvO2) and venoarterial PCO2 difference (PvaCO2) were thoroughly investigated. METHODS Thirteen children <1 year of age who underwent open-heart surgery were prospectively enrolled. In addition to conventional postoperative monitoring, transpulmonary thermodilution (TPTD) was used to monitor cardiac output and calculate oxygen delivery and consumption. In parallel with each TPTD measurement, arterial and central venous blood gas values were recorded. Global haemodynamic parameters and oxygenation measurements were compared with weighted linear regression statistics and Pearson's correlation coefficient. RESULTS Data from 145 TPTD measurements and 304 blood gas samples were recorded. The early postoperative period was characterized by a supply-dependent oxygen consumption, as demonstrated by the direct correlation between the change in oxygen delivery and consumption (r = 0.62, P < 0.001). Regarding haemodynamic parameters, none of the heart rate, mean arterial pressure or cardiac index correlated with the measured ScvO2. However, the ScvO2 and PvaCO2 were found to correlate significantly (r = −0.49, P < 0.001), and both strongly related to oxygen extraction. CONCLUSIONS Both the ScvO2 and PvaCO2 are reliable and comparable parameters in following tissue oxygen balance during the early postoperative course after open-heart surgery in neonates and infants. As part of multiparameter monitoring, our data highlight the importance of regular ScvO2 measurements and

  1. Quantitative assessment of reactive oxygen sonochemically generated by cavitation bubbles

    NASA Astrophysics Data System (ADS)

    Yasuda, Jun; Miyashita, Takuya; Taguchi, Kei; Yoshizawa, Shin; Umemura, Shin-ichiro

    2015-07-01

    Acoustic cavitation bubbles can induce not only a thermal bioeffect but also a chemical bioeffect. When cavitation bubbles collapse and oscillate violently, they produce reactive oxygen species (ROS) that cause irreversible changes to the tissue. A sonosensitizer can promote such ROS generation. A treatment method using a sonosensitizer is called sonodynamic treatment. Rose bengal (RB) is one of the sonosensitizers whose in vivo and in vitro studies have been reported. In sonodynamic treatment, it is important to produce ROS at a high efficiency. For the efficient generation of ROS, a triggered high-intensity focused ultrasound (HIFU) sequence has been proposed. In this study, cavitation bubbles were generated in a chamber where RB solution was sealed, and a high-speed camera captured the behavior of these cavitation bubbles. The amount of ROS was also quantified by a potassium iodide (KI) method and compared with high-speed camera pictures to investigate the effectiveness of the triggered HIFU sequence. As a result, ROS could be obtained efficiently by this sequence.

  2. The Determination of the Percent of Oxygen in Air Using a Gas Pressure Sensor

    ERIC Educational Resources Information Center

    Gordon, James; Chancey, Katherine

    2005-01-01

    The experiment of determination of the percent of oxygen in air is performed in a general chemistry laboratory in which students compare the results calculated from the pressure measurements obtained with the calculator-based systems to those obtained in a water-measurement method. This experiment allows students to explore a fundamental reaction…

  3. Fiber optic spectroscopy of blood for oxygen saturation sensor development: hematocrit effect

    NASA Astrophysics Data System (ADS)

    Anderson, Charles D.; Wlodarczyk, Marek T.

    1993-05-01

    We present experimental results from fiberoptic spectroscopy apparatus measuring whole blood's optical attenuation over a continuous wavelength range of 0.6 - 1.0 micrometers . Relative optical density (OD) spectra at a number of hematocrit values and oxygenation levels is obtained. The role of hematocrit in affecting spectral shape is discussed based upon relatively simple relationships derived from experimental data. A specific partial differential equation emerges from the analysis. This equation relates scatter-dependent experimental OD to oxygen saturation, hematocrit and purely absorbing, nonscattering constituents--and is obeyed over an extended wavelength range. A three-wavelength algorithm using experimental absorbances at LED-compatible wavelengths accurately provides both hematocrit and oxygen saturation values, for hematocrit levels between 0.2 and 0.6 in the presence of oxygenated and reduced Hb species. Optical system comparison between spectroscopic data and modeled LED behavior indicates the algorithm can be mapped to the design and implementation of discrete components for clinical use.

  4. A non-invasive fluorescence-based oxygen sensor and platform for studying cell responses to metabolic agents in real-time

    NASA Astrophysics Data System (ADS)

    Buchapudi, Koutilya Reddy

    A fluorescence-based sensor in a transverse flow/stop measurement platform has been developed to determine real-time changes in oxygen consumption rates for cell metabolic studies. The oxygen sensitive fluorophore platinum octaethylporphyrin was embedded in a cellulose acetate matrix and affixed to a fiber optic bundle, which provided for transmission of the excitation and emission wavelengths of the film. The fiber optic bundle was sealed in a sensor head that can be used in standard 24-well plates common to research labs. The utility of the sensor and sensing platform were determined by measuring the changes in oxygen consumption rates of Candida albicans during 90/30 s flow/stop cycles. Exposure of these cells to metabolic antagonists and an enhancer showed the expected decrease and increase in oxygen consumption rates in real time. The applicability of the platform to biological studies is illustrated by determination of synergistic activities between antifungal drugs and fluoride exposure in Candida albicans. The robustness of the fluorophore film is demonstrated by perfusion with different media and analyte conditions in the absence of cells. For stop cycle time intervals less than 1 minute the sensor exhibited a rapid and fairly linear change in fluorescence intensity to changing oxygen concentrations in the measurement chamber. Flow cycle fluorescence intensities were used as a baseline correction for treating the stop cycle fluorescence peaks.

  5. Machine vision guided sensor positioning system for leaf temperature assessment.

    PubMed

    Kim, Y; Ling, P P

    2001-01-01

    A sensor positioning system was developed for monitoring plants' well-being using a non-contact sensor. Image processing algorithms were developed to identify a target region on a plant leaf. A novel algorithm to recover view depth was developed by using a camera equipped with a computer-controlled zoom lens. The methodology has improved depth recovery resolution over a conventional monocular imaging technique. An algorithm was also developed to find a maximum enclosed circle on a leaf surface so the conical field-of-view of an infrared temperature sensor could be filled by the target without peripheral noise. The center of the enclosed circle and the estimated depth were used to define the sensor 3-D location for accurate plant temperature measurement. PMID:12088029

  6. Machine vision guided sensor positioning system for leaf temperature assessment

    NASA Technical Reports Server (NTRS)

    Kim, Y.; Ling, P. P.; Janes, H. W. (Principal Investigator)

    2001-01-01

    A sensor positioning system was developed for monitoring plants' well-being using a non-contact sensor. Image processing algorithms were developed to identify a target region on a plant leaf. A novel algorithm to recover view depth was developed by using a camera equipped with a computer-controlled zoom lens. The methodology has improved depth recovery resolution over a conventional monocular imaging technique. An algorithm was also developed to find a maximum enclosed circle on a leaf surface so the conical field-of-view of an infrared temperature sensor could be filled by the target without peripheral noise. The center of the enclosed circle and the estimated depth were used to define the sensor 3-D location for accurate plant temperature measurement.

  7. MoS2 oxygen sensor with gate voltage stress induced performance enhancement

    NASA Astrophysics Data System (ADS)

    Tong, Yu; Lin, Zhenhua; Thong, John T. L.; Chan, Daniel S. H.; Zhu, Chunxiang

    2015-09-01

    Two-dimensional (2D) materials have recently attracted wide attention and rapidly established themselves in various applications. In particular, 2D materials are regarded as promising building blocks for gas sensors due to their high surface-to-volume ratio, ease in miniaturization, and flexibility in enabling wearable electronics. Compared with other 2D materials, MoS2 is particularly intriguing because it has been widely researched and exhibits semiconducting behavior. Here, we have fabricated MoS2 resistor based O2 sensors with a back gate configuration on a 285 nm SiO2/Si substrate. The effects of applying back gate voltage stress on O2 sensing performance have been systematically investigated. With a positive gate voltage stress, the sensor response improves and the response is improved to 29.2% at O2 partial pressure of 9.9 × 10-5 millibars with a +40 V back-gate bias compared to 21.2% at O2 partial pressure of 1.4 × 10-4 millibars without back-gate bias; while under a negative gate voltage stress of -40 V, a fast and full recovery can be achieved at room temperature. In addition, a method in determining O2 partial pressure with a detectability as low as 6.7 × 10-7 millibars at a constant vacuum pressure is presented and its potential as a vacuum gauge is briefly discussed.

  8. A novel method for assessing the 3-D orientation accuracy of inertial/magnetic sensors.

    PubMed

    Faber, Gert S; Chang, Chien-Chi; Rizun, Peter; Dennerlein, Jack T

    2013-10-18

    A novel method for assessing the accuracy of inertial/magnetic sensors is presented. The method, referred to as the "residual matrix" method, is advantageous because it decouples the sensor's error with respect to Earth's gravity vector (attitude residual error: pitch and roll) from the sensor's error with respect to magnetic north (heading residual error), while remaining insensitive to singularity problems when the second Euler rotation is close to ±90°. As a demonstration, the accuracy of an inertial/magnetic sensor mounted to a participant's forearm was evaluated during a reaching task in a laboratory. Sensor orientation was measured internally (by the inertial/magnetic sensor) and externally using an optoelectronic measurement system with a marker cluster rigidly attached to the sensor's enclosure. Roll, pitch and heading residuals were calculated using the proposed novel method, as well as using a common orientation assessment method where the residuals are defined as the difference between the Euler angles measured by the inertial sensor and those measured by the optoelectronic system. Using the proposed residual matrix method, the roll and pitch residuals remained less than 1° and, as expected, no statistically significant difference between these two measures of attitude accuracy was found; the heading residuals were significantly larger than the attitude residuals but remained below 2°. Using the direct Euler angle comparison method, the residuals were in general larger due to singularity issues, and the expected significant difference between inertial/magnetic sensor attitude and heading accuracy was not present. PMID:24016678

  9. Pinhole cameras as sensors for atomic oxygen in orbit: Application to attitude determination of the LDEF

    NASA Technical Reports Server (NTRS)

    Peters, Palmer N.; Gregory, John C.

    1992-01-01

    Images produced by pinhole cameras using film sensitive to atomic oxygen provide information on the ratio of spacecraft orbital velocity to the most probable thermal speed of oxygen atoms, provided the spacecraft orientation is maintained stable relative to the orbital direction. Alternatively, information on the spacecraft attitude relative to the orbital velocity can be obtained, provided that corrections are properly made for thermal spreading and a corotating atmosphere. The Long Duration Exposure Facility (LDEF) orientation, uncorrected for a corotating atmosphere, was determined to be yawed 8.0 +/- 0.4 degrees from its nominal attitude, with an estimated +/- 0.35 degree oscillation in yaw. The integrated effect of inclined orbit and corotating atmosphere produces an apparent oscillation in the observed yaw direction, suggesting that the LDEF attitude measurement will indicate even better stability when corrected for a corotating atmosphere. The measured thermal spreading is consistent with major exposure occurring during high solar activity, which occurred late during the LDEF mission.

  10. Atomic Oxygen Sensors Based on Nanograin ZnO Films Prepared by Pulse Laser Deposition

    SciTech Connect

    Wang Yunfei; Chen Xuekang; Li Zhonghua; Zheng Kuohai; Wang Lanxi; Feng Zhanzu; Yang Shengsheng

    2009-01-05

    High-quality nanograin ZnO thin films were deposited on c-plane sapphire (Al{sub 2}O{sub 3}) substrates by pulse laser deposition (PLD). Scanning electron microscopy (SEM) and x-ray diffraction (XRD) were used to characterize the samples. The structural and morphological properties of ZnO films under different deposition temperature have been investigated before and after atomic oxygen (AO) treatment. XRD has shown that the intensity of the (0 0 2) peak increases and its FWHM value decreases after AO treatment. The AO sensing characteristics of nano ZnO film also has been investigated in a ground-based atomic oxygen simulation facility. The results show that the electrical conductivity of nanograin ZnO films decreases with increasing AO fluence and that the conductivity of the films can be recovered by heating.

  11. The Oxygen Sensor PHD2 Controls Dendritic Spines and Synapses via Modification of Filamin A

    PubMed Central

    Segura, Inmaculada; Lange, Christian; Knevels, Ellen; Moskalyuk, Anastasiya; Pulizzi, Rocco; Eelen, Guy; Chaze, Thibault; Tudor, Cicerone; Boulegue, Cyril; Holt, Matthew; Daelemans, Dirk; Matondo, Mariette; Ghesquière, Bart; Giugliano, Michele; Ruiz de Almodovar, Carmen; Dewerchin, Mieke; Carmeliet, Peter

    2016-01-01

    Summary Neuronal function is highly sensitive to changes in oxygen levels, but how hypoxia affects dendritic spine formation and synaptogenesis is unknown. Here we report that hypoxia, chemical inhibition of the oxygen-sensing prolyl hydroxylase domain proteins (PHDs), and silencing of Phd2 induce immature filopodium-like dendritic protrusions, promote spine regression, reduce synaptic density, and decrease the frequency of spontaneous action potentials independently of HIF signaling. We identified the actin cross-linker filamin A (FLNA) as a target of PHD2 mediating these effects. In normoxia, PHD2 hydroxylates the proline residues P2309 and P2316 in FLNA, leading to von Hippel-Lindau (VHL)-mediated ubiquitination and proteasomal degradation. In hypoxia, PHD2 inactivation rapidly upregulates FLNA protein levels because of blockage of its proteasomal degradation. FLNA upregulation induces more immature spines, whereas Flna silencing rescues the immature spine phenotype induced by PHD2 inhibition. PMID:26972007

  12. The Oxygen Sensor PHD2 Controls Dendritic Spines and Synapses via Modification of Filamin A.

    PubMed

    Segura, Inmaculada; Lange, Christian; Knevels, Ellen; Moskalyuk, Anastasiya; Pulizzi, Rocco; Eelen, Guy; Chaze, Thibault; Tudor, Cicerone; Boulegue, Cyril; Holt, Matthew; Daelemans, Dirk; Matondo, Mariette; Ghesquière, Bart; Giugliano, Michele; Ruiz de Almodovar, Carmen; Dewerchin, Mieke; Carmeliet, Peter

    2016-03-22

    Neuronal function is highly sensitive to changes in oxygen levels, but how hypoxia affects dendritic spine formation and synaptogenesis is unknown. Here we report that hypoxia, chemical inhibition of the oxygen-sensing prolyl hydroxylase domain proteins (PHDs), and silencing of Phd2 induce immature filopodium-like dendritic protrusions, promote spine regression, reduce synaptic density, and decrease the frequency of spontaneous action potentials independently of HIF signaling. We identified the actin cross-linker filamin A (FLNA) as a target of PHD2 mediating these effects. In normoxia, PHD2 hydroxylates the proline residues P2309 and P2316 in FLNA, leading to von Hippel-Lindau (VHL)-mediated ubiquitination and proteasomal degradation. In hypoxia, PHD2 inactivation rapidly upregulates FLNA protein levels because of blockage of its proteasomal degradation. FLNA upregulation induces more immature spines, whereas Flna silencing rescues the immature spine phenotype induced by PHD2 inhibition. PMID:26972007

  13. MoS{sub 2} oxygen sensor with gate voltage stress induced performance enhancement

    SciTech Connect

    Tong, Yu; Lin, Zhenhua; Thong, John T. L.; Chan, Daniel S. H.; Zhu, Chunxiang

    2015-09-21

    Two-dimensional (2D) materials have recently attracted wide attention and rapidly established themselves in various applications. In particular, 2D materials are regarded as promising building blocks for gas sensors due to their high surface-to-volume ratio, ease in miniaturization, and flexibility in enabling wearable electronics. Compared with other 2D materials, MoS{sub 2} is particularly intriguing because it has been widely researched and exhibits semiconducting behavior. Here, we have fabricated MoS{sub 2} resistor based O{sub 2} sensors with a back gate configuration on a 285 nm SiO{sub 2}/Si substrate. The effects of applying back gate voltage stress on O{sub 2} sensing performance have been systematically investigated. With a positive gate voltage stress, the sensor response improves and the response is improved to 29.2% at O{sub 2} partial pressure of 9.9 × 10{sup −5} millibars with a +40 V back-gate bias compared to 21.2% at O{sub 2} partial pressure of 1.4 × 10{sup −4} millibars without back-gate bias; while under a negative gate voltage stress of −40 V, a fast and full recovery can be achieved at room temperature. In addition, a method in determining O{sub 2} partial pressure with a detectability as low as 6.7 × 10{sup −7} millibars at a constant vacuum pressure is presented and its potential as a vacuum gauge is briefly discussed.

  14. A miniature photoelectrochemical sensor based on organic electrochemical transistor for sensitive determination of chemical oxygen demand in wastewaters.

    PubMed

    Liao, Jianjun; Lin, Shiwei; Zeng, Min; Yang, Yue

    2016-05-01

    A three-electrode configuration is often required in the conventional photoelectrochemical measurements. Nevertheless, one common drawback is the reference electrode and the counter electrode used in the measurements, which has been proved to be an impediment for the miniaturization. In this study, a simple, cost-effective and miniature photoelectrochemical sensor based on high sensitive organic electrochemical transistor (OECT) is developed and used for the determination of chemical oxygen demand (COD) in wastewaters. The devices show detection limit down to 0.01 mg/L COD, which is two orders of magnitude better than that of the conventional photoelectrochemical method. The excellent sensing performance can be contributed to the novel sensing mechanism of OECT devices. That is, the devices are sensitive to the potential changes induced by the photoelectrochemical reaction on TiO2 nanotube arrays gate electrodes. Real sample analyses are also carried out. The results demonstrate that the measured COD values using the OECT devices and the standard dichromate methods are in a good agreement. Since the proposed sensor is constructed on a miniature transistor, it is expected that the device shows a promising application on the integrated COD monitoring platform. PMID:26971805

  15. A Lab Assembled Microcontroller-Based Sensor Module for Continuous Oxygen Measurement in Portable Hypoxia Chambers

    PubMed Central

    Mathupala, Saroj P.; Kiousis, Sam; Szerlip, Nicholas J.

    2016-01-01

    Background Hypoxia-based cell culture experiments are routine and essential components of in vitro cancer research. Most laboratories use low-cost portable modular chambers to achieve hypoxic conditions for cell cultures, where the sealed chambers are purged with a gas mixture of preset O2 concentration. Studies are conducted under the assumption that hypoxia remains unaltered throughout the 48 to 72 hour duration of such experiments. Since these chambers lack any sensor or detection system to monitor gas-phase O2, the cell-based data tend to be non-uniform due to the ad hoc nature of the experimental setup. Methodology With the availability of low-cost open-source microcontroller-based electronic project kits, it is now possible for researchers to program these with easy-to-use software, link them to sensors, and place them in basic scientific apparatus to monitor and record experimental parameters. We report here the design and construction of a small-footprint kit for continuous measurement and recording of O2 concentration in modular hypoxia chambers. The low-cost assembly (US$135) consists of an Arduino-based microcontroller, data-logging freeware, and a factory pre-calibrated miniature O2 sensor. A small, intuitive software program was written by the authors to control the data input and output. The basic nature of the kit will enable any student in biology with minimal experience in hobby-electronics to assemble the system and edit the program parameters to suit individual experimental conditions. Results/Conclusions We show the kit’s utility and stability of data output via a series of hypoxia experiments. The studies also demonstrated the critical need to monitor and adjust gas-phase O2 concentration during hypoxia-based experiments to prevent experimental errors or failure due to partial loss of hypoxia. Thus, incorporating the sensor-microcontroller module to a portable hypoxia chamber provides a researcher a capability that was previously available

  16. Stochastic sensors designed for assessment of biomarkers specific to obesity.

    PubMed

    Cioates Negut, Catalina; Stefan-van Staden, Raluca-Ioana; Ungureanu, Eleonora-Mihaela; Udeanu, Denisa Ioana

    2016-09-01

    Two stochastic sensors based on the following oleamides: 1-adamantyloleamide and N,N-dimethyl-N-(2-oleylamidoethyl)amine physically immobilized on graphite paste were designed. The sensors were able to determine simultaneously from the whole blood of Wistar rats three biomarkers specific to obesity: leptin, interleukin-6 (IL-6) and plasminogen activator inhibitor 1 (PAI-1). The whole blood samples were obtained from Wistar rats treated with oleoylethanolamide (OEA), (Z)-N-[(1S)-2-hidroxy-1-(phenylmethyl) ethyl]-9octadecenamide (OLA), and with the aqueous solution of 1% Tween 80 used as solvent for oleamides formulations (control samples). The proposed sensors were very sensitive and reliable for the assay of obesity biomarkers in whole blood of rats. PMID:27288757

  17. Assessment of space sensors for ocean pollution monitoring

    NASA Technical Reports Server (NTRS)

    Alvarado, U. R.; Tomiyasu, K.; Gulatsi, R. L.

    1980-01-01

    Several passive and active microwave, as well as passive optical remote sensors, applicable to the monitoring of oil spills and waste discharges at sea, are considered. The discussed types of measurements relate to: (1) spatial distribution and properties of the pollutant, and (2) oceanic parameters needed to predict the movement of the pollutants and their impact upon land. The sensors, operating from satellite platforms at 700-900 km altitudes, are found to be useful in mapping the spread of oil in major oil spills and in addition, can be effective in producing wind and ocean parameters as inputs to oil trajectory and dispersion models. These capabilities can be used in countermeasures.

  18. Tetra(1,1,4,4-tetramethyl-6,7-tetralino)porphyrazine as a novel luminescence sensor of laser-induced singlet oxygen generation in solutions

    SciTech Connect

    Krasnovskii, A A; Schweitzer, C; Leismann, H; Tanielian, C; Luk'yanets, Evgenii A

    2000-05-31

    Absorption and fluorescence spectra and quantum yields of fluorescence and singlet oxygen generation were studied in air-saturated solutions of a newly synthesised dye, tetra(1,1,4,4-tetramethyl-6,7-tetralino)porphyrazine (TMTP), in benzene. Photophysical properties of TMTP are similar to those of previously studied tetra(4-tert-butyl) phthalocyanine (TBPc). However, the TMTP absorption and fluorescence bands are shifted to the longer wavelengths compared with those of TBPc. The laser-induced generation of singlet molecular oxygen {sup 1}O{sub 2} in TMTP solutions caused strong singlet oxygen-sensitised delayed fluorescence of the dye. The efficiency of singlet-oxygen-sensitised formation of excited TMTP molecules is two times higher than that of TBPc. It is shown that TMTP can serve as an efficient luminescence sensor of singlet oxygen. (laser applications and other topics in quantum electronics)

  19. A novel approach to the assess biotic oxygen consumption in marine sediment communities

    NASA Astrophysics Data System (ADS)

    Baranov, Victor; Queiros, Ana; Widdicombe, Stephen; Stephens, Nick; Lessin, Gennadi; Krause, Stefan; Lewandowski, Joerg

    2016-04-01

    Bioturbation , the mixing of the sediment matrix by burrowing animals impacts sediment metabolism, including respiration through redistribution of particulate organics, changes in bacterial biota diversity and acitivity, as well as via burrowing fauna's own metabolism. Bioturbation, reflecting faunal activity, is also a proxy for the general sedimentary ecosystem health, and can be impacted by many of emerging marine environmental issues such as ocean acidification, warming and the occurrence of heat waves. Sedimentary oxygen consumption is often taken as a proxy for the activity of bioturbating fauna, but determining baselines can be difficult because of the confounding effects of other fauna and microbes present in sediments, as well as irnorganic processes that consume oxygen. Limitations therefore exist in current methodologies, and numerous confounding factors are hampering progress in this area. Here, we present novel method for the assessment of sediment respiration which is expected to be affected only by the biogenic oxygen consumption (namely aerobic respiration). As long as tracer reduction "immune" to inorganic oxygen consumption, so that measurements using this method can be used, alongside traditional methods, to decouple biological respiration from inorganic oxygen consumption reactions. The tracer is easily detectable, non-toxic and can be applied in systems with constant oxygen supply. The latter allow for incubation without the need to to work with unsealed experimental units, bringing procedural advantage over traditional methods. Consequently assessed bioturbating fauna is not exposed to hypoxia and additional stress. Here, we had applied system for the first time to investigate impacts of a common North-Atlantic bioturbator, the brittle star Amphiura filiformis, - on respiration of marine sediments. Two series of experiments were conducted with animals and sediment collected from Cawsand Bay, Plymouth, UK Preliminary results show that tracer

  20. Pinhole cameras as sensors for atomic oxygen in orbit; application to attitude determination of the LDEF

    NASA Technical Reports Server (NTRS)

    Peters, Palmer N.; Gregory, John C.

    1991-01-01

    Images produced by pinhole cameras using film sensitive to atomic oxygen provide information on the ratio of spacecraft orbital velocity to the most probable thermal speed of oxygen atoms, provided the spacecraft orientation is maintained stable relative to the orbital direction. Alternatively, as it is described, information on the spacecraft attitude relative to the orbital velocity can be obtained, provided that corrections are properly made for thermal spreading and a co-rotating atmosphere. The LDEF orientation, uncorrected for a co-rotating atmosphere, was determined to be yawed 8.0 minus/plus 0.4 deg from its nominal attitude, with an estimated minus/plus 0.35 deg oscillation in yaw. The integrated effect of inclined orbit and co-rotating atmosphere produces an apparent oscillation in the observed yaw direction, suggesting that the LDEF attitude measurement will indicate even better stability when corrected for a co-rotating atmosphere. The measured thermal spreading is consistent with major exposure occurring during high solar activity, which occurred late during the LDEF mission.

  1. Low Power Resistive Oxygen Sensor Based on Sonochemical SrTi0.6Fe0.4O2.8 (STFO40).

    PubMed

    Stratulat, Alisa; Serban, Bogdan-Catalin; de Luca, Andrea; Avramescu, Viorel; Cobianu, Cornel; Brezeanu, Mihai; Buiu, Octavian; Diamandescu, Lucian; Feder, Marcel; Ali, Syed Zeeshan; Udrea, Florin

    2015-01-01

    The current paper reports on a sonochemical synthesis method for manufacturing nanostructured (typical grain size of 50 nm) SrTi0.6Fe0.4O2.8 (Sono-STFO40) powder. This powder is characterized using X ray-diffraction (XRD), Mössbauer spectroscopy and Scanning Electron Microscopy (SEM), and results are compared with commercially available SrTi0.4Fe0.6O2.8 (STFO60) powder. In order to manufacture resistive oxygen sensors, both Sono-STFO40 and STFO60 are deposited, by dip-pen nanolithography (DPN) method, on an SOI (Silicon-on-Insulator) micro-hotplate, employing a tungsten heater embedded within a dielectric membrane. Oxygen detection tests are performed in both dry (RH = 0%) and humid (RH = 60%) nitrogen atmosphere, varying oxygen concentrations between 1% and 16% (v/v), at a constant heater temperature of 650 °C. The oxygen sensor, based on the Sono-STFO40 sensing layer, shows good sensitivity, low power consumption (80 mW), and short response time (25 s). These performance are comparable to those exhibited by state-of-the-art O2 sensors based on STFO60, thus proving Sono-STFO40 to be a material suitable for oxygen detection in harsh environments. PMID:26205267

  2. Low Power Resistive Oxygen Sensor Based on Sonochemical SrTi0.6Fe0.4O2.8 (STFO40)

    PubMed Central

    Stratulat, Alisa; Serban, Bogdan-Catalin; de Luca, Andrea; Avramescu, Viorel; Cobianu, Cornel; Brezeanu, Mihai; Buiu, Octavian; Diamandescu, Lucian; Feder, Marcel; Ali, Syed Zeeshan; Udrea, Florin

    2015-01-01

    The current paper reports on a sonochemical synthesis method for manufacturing nanostructured (typical grain size of 50 nm) SrTi0.6Fe0.4O2.8 (Sono-STFO40) powder. This powder is characterized using X ray-diffraction (XRD), Mössbauer spectroscopy and Scanning Electron Microscopy (SEM), and results are compared with commercially available SrTi0.4Fe0.6O2.8 (STFO60) powder. In order to manufacture resistive oxygen sensors, both Sono-STFO40 and STFO60 are deposited, by dip-pen nanolithography (DPN) method, on an SOI (Silicon-on-Insulator) micro-hotplate, employing a tungsten heater embedded within a dielectric membrane. Oxygen detection tests are performed in both dry (RH = 0%) and humid (RH = 60%) nitrogen atmosphere, varying oxygen concentrations between 1% and 16% (v/v), at a constant heater temperature of 650 °C. The oxygen sensor, based on the Sono-STFO40 sensing layer, shows good sensitivity, low power consumption (80 mW), and short response time (25 s). These performance are comparable to those exhibited by state-of-the-art O2 sensors based on STFO60, thus proving Sono-STFO40 to be a material suitable for oxygen detection in harsh environments. PMID:26205267

  3. Earbud-Based Sensor for the Assessment of Energy Expenditure, Heart Rate, and VO2max

    PubMed Central

    LeBoeuf, Steven F.; Aumer, Michael E.; Kraus, William E.; Johnson, Johanna L.; Duscha, Brian

    2014-01-01

    Introduction/Purpose The goal of this program was to determine the feasibility of a novel noninvasive, highly miniaturized optomechanical earbud sensor for accurately estimating total energy expenditure (TEE) and maximum oxygen consumption (VO2max). The optomechanical sensor module, small enough to fit inside commercial audio earbuds, was previously developed to provide a seamless way to measure blood flow information during daily life activities. The sensor module was configured to continuously measure physiological information via photoplethysmography (PPG) and physical activity information via accelerometry. This information was digitized and sent to a microprocessor where digital signal processing (DSP) algorithms extract physiological metrics in real-time. These metrics were streamed wirelessly from the earbud to a computer. Methods In this study, 23 subjects of multiple physical habitus were divided into a training group of 14 subjects and a validation group of 9 subjects. Each subject underwent the same exercise measurement protocol consisting of treadmill-based cardiopulmonary exercise (CPX) testing to reach VO2max. Benchmark sensors included a 12-lead electrocardiography (ECG) sensor for measuring heart rate, a calibrated treadmill for measuring distance and speed, and a gas-exchange analysis instrument for measuring TEE and VO2max. The earbud sensor was the device under test (DUT). Benchmark and DUT data collected from the 14-person training dataset study were integrated into a preconceived statistical model for correlating benchmark data with earbud sensor data. Coefficients were optimized, and the optimized model was validated in the 9-person validation dataset. Results It was observed that the earbud sensor estimated TEE and VO2max with mean ± SD percent estimation errors of −0.7 ± 7.4% and −3.2 ± 7.3% respectively. Conclusion The earbud sensor can accurately estimate TEE and VO2max during CPX testing. PMID:24743110

  4. Micelle-Encapsulated Quantum Dot-Porphyrin Assemblies as in Vivo Two-Photon Oxygen Sensors

    PubMed Central

    Lemon, Christopher M.; Karnas, Elizabeth; Han, Xiaoxing; Bruns, Oliver T.; Kempa, Thomas J.; Fukumura, Dai; Bawendi, Moungi G.; Jain, Rakesh K.; Duda, Dan G.; Nocera, Daniel G.

    2016-01-01

    Micelles have been employed to encapsulate the supramolecular assembly of quantum dots with palladium(II) porphyrins for the quantification of O2 levels in aqueous media and in vivo. Förster resonance energy transfer from the quantum dot (QD) to the palladium porphyrin provides a means for signal transduction under both one- and two-photon excitation. The palladium porphyrins are sensitive to O2 concentrations in the range of 0–160 Torr. The micelle-encapsulated QD-porphyrin assemblies have been employed for in vivo multiphoton imaging and lifetime-based oxygen measurements in mice with chronic dorsal skinfold chambers or cranial windows. Our results establish the utility of the QD-micelle approach for in vivo biological sensing applications. PMID:26149349

  5. Accuracy of different sensors for the estimation of pollutant concentrations (total suspended solids, total and dissolved chemical oxygen demand) in wastewater and stormwater.

    PubMed

    Lepot, Mathieu; Aubin, Jean-Baptiste; Bertrand-Krajewski, Jean-Luc

    2013-01-01

    Many field investigations have used continuous sensors (turbidimeters and/or ultraviolet (UV)-visible spectrophotometers) to estimate with a short time step pollutant concentrations in sewer systems. Few, if any, publications compare the performance of various sensors for the same set of samples. Different surrogate sensors (turbidity sensors, UV-visible spectrophotometer, pH meter, conductivity meter and microwave sensor) were tested to link concentrations of total suspended solids (TSS), total and dissolved chemical oxygen demand (COD), and sensors' outputs. In the combined sewer at the inlet of a wastewater treatment plant, 94 samples were collected during dry weather, 44 samples were collected during wet weather, and 165 samples were collected under both dry and wet weather conditions. From these samples, triplicate standard laboratory analyses were performed and corresponding sensors outputs were recorded. Two outlier detection methods were developed, based, respectively, on the Mahalanobis and Euclidean distances. Several hundred regression models were tested, and the best ones (according to the root mean square error criterion) are presented in order of decreasing performance. No sensor appears as the best one for all three investigated pollutants. PMID:23863442

  6. An Automated Method for Navigation Assessment for Earth Survey Sensors Using Island Targets

    NASA Technical Reports Server (NTRS)

    Patt, F. S.; Woodward, R. H.; Gregg, W. W.

    1997-01-01

    An automated method has been developed for performing navigation assessment on satellite-based Earth sensor data. The method utilizes islands as targets which can be readily located in the sensor data and identified with reference locations. The essential elements are an algorithm for classifying the sensor data according to source, a reference catalogue of island locations, and a robust pattern-matching algorithm for island identification. The algorithms were developed and tested for the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), an ocean colour sensor. This method will allow navigation error statistics to be automatically generated for large numbers of points, supporting analysis over large spatial and temporal ranges.

  7. A framework for harmonizing sensor data to support embedded health assessment.

    PubMed

    Skubic, Marjorie; Jimison, Holly; Keller, James; Popescu, Mihail; Rantz, Marilyn; Kaye, Jeff; Pavel, Misha

    2014-01-01

    The use of in-home and mobile sensing is likely to be a key component of future care and has recently been studied by many research groups world-wide. Researchers have shown that embedded sensors can be used for health assessment such as early illness detection and the management of chronic health conditions. However, research collaboration and data sharing have been hampered by disparate sets of sensors and data collection methods. To date, there have been no studies to investigate common measures that can be used across multiple sites with different types of sensors, which would facilitate large scale studies and reuse of existing datasets. In this paper, we propose a framework for harmonizing heterogeneous sensor data through an intermediate layer, the Conceptual Sensor, which maps physical measures to clinical space. Examples are included for sleep quality and ambulatory physical function. PMID:25570314

  8. Assessing Routing Strategies for Cognitive Radio Sensor Networks

    PubMed Central

    Zubair, Suleiman; Fisal, Norsheila; Baguda, Yakubu S.; Saleem, Kashif

    2013-01-01

    Interest in the cognitive radio sensor network (CRSN) paradigm has gradually grown among researchers. This concept seeks to fuse the benefits of dynamic spectrum access into the sensor network, making it a potential player in the next generation (NextGen) network, which is characterized by ubiquity. Notwithstanding its massive potential, little research activity has been dedicated to the network layer. By contrast, we find recent research trends focusing on the physical layer, the link layer and the transport layers. The fact that the cross-layer approach is imperative, due to the resource-constrained nature of CRSNs, can make the design of unique solutions non-trivial in this respect. This paper seeks to explore possible design opportunities with wireless sensor networks (WSNs), cognitive radio ad-hoc networks (CRAHNs) and cross-layer considerations for implementing viable CRSN routing solutions. Additionally, a detailed performance evaluation of WSN routing strategies in a cognitive radio environment is performed to expose research gaps. With this work, we intend to lay a foundation for developing CRSN routing solutions and to establish a basis for future work in this area. PMID:24077319

  9. Assessing routing strategies for cognitive radio sensor networks.

    PubMed

    Zubair, Suleiman; Fisal, Norsheila; Baguda, Yakubu S; Saleem, Kashif

    2013-01-01

    Interest in the cognitive radio sensor network (CRSN) paradigm has gradually grown among researchers. This concept seeks to fuse the benefits of dynamic spectrum access into the sensor network, making it a potential player in the next generation (NextGen) network, which is characterized by ubiquity. Notwithstanding its massive potential, little research activity has been dedicated to the network layer. By contrast, we find recent research trends focusing on the physical layer, the link layer and the transport layers. The fact that the cross-layer approach is imperative, due to the resource-constrained nature of CRSNs, can make the design of unique solutions non-trivial in this respect. This paper seeks to explore possible design opportunities with wireless sensor networks (WSNs), cognitive radio ad-hoc networks (CRAHNs) and cross-layer considerations for implementing viable CRSN routing solutions. Additionally, a detailed performance evaluation of WSN routing strategies in a cognitive radio environment is performed to expose research gaps. With this work, we intend to lay a foundation for developing CRSN routing solutions and to establish a basis for future work in this area. PMID:24077319

  10. Fiber optic sensor for the assessment of breathing effort

    NASA Astrophysics Data System (ADS)

    Babchenko, Anatoly; Turinvenko, Sergei; Khanokh, Boris; Nitzan, Meir

    1995-01-01

    Several methods have been developed for the qualitative and quantitative measurement of breathing effort. The most useful kind of breathing pattern monitor includes devices for recording chest and abdomen dimension changes, such as impedance plethysmography and respiratory induction plethysmography. These devices can measure the tidal volume in relative terms, and even measure it in absolute terms after suitable calibration. In this study a novel method for measuring chest circumference based on an optical fiber is presented. The sensor is based on the measurement of light transmitted through a bent optical fiber, which is connected to an elastic band, wrapped around the chest, and whose radius of curvature changes due to the respiratory act. The amount of transmitted light is related to the radius of curvature of the fiber which depends on the chest circumference. The output of the respiratory sensor was checked qualitatively by changing the respiration rate and depth. The changes in breathing effort were clearly demonstrated in the sensor output recording. The respiratory effort was also correlated with the heart rate, measured by photoplethysmography. Statistically significant correlation was found between the lungs' volume and the heart rate, but the correlation coefficient was not high.

  11. A Bayesian Framework for the Automated Online Assessment of Sensor Data Quality

    PubMed Central

    Smith, Daniel; Timms, Greg; De Souza, Paulo; D'Este, Claire

    2012-01-01

    Online automated quality assessment is critical to determine a sensor's fitness for purpose in real-time applications. A Dynamic Bayesian Network (DBN) framework is proposed to produce probabilistic quality assessments and represent the uncertainty of sequentially correlated sensor readings. This is a novel framework to represent the causes, quality state and observed effects of individual sensor errors without imposing any constraints upon the physical deployment or measured phenomenon. It represents the casual relationship between quality tests and combines them in a way to generate uncertainty estimates of samples. The DBN was implemented for a particular marine deployment of temperature and conductivity sensors in Hobart, Australia. The DBN was shown to offer a substantial average improvement (34%) in replicating the error bars that were generated by experts when compared to a fuzzy logic approach. PMID:23012554

  12. Microfluidic surface-enhanced Raman scattering sensors based on nanopillar forests realized by an oxygen-plasma-stripping-of-photoresist technique.

    PubMed

    Mao, Haiyang; Wu, Wengang; She, Didi; Sun, Gongchen; Lv, Pengpeng; Xu, Jun

    2014-01-15

    A novel surface-enhanced Raman scattering (SERS) sensor is developed for real-time and highly repeatable detection of trace chemical and biological indicators. The sensor consists of a polydimethylsiloxane (PDMS) microchannel cap and a nanopillar forest-based open SERS-active substrate. The nanopillar forests are fabricated based on a new oxygen-plasma-stripping-of-photoresist technique. The enhancement factor (EF) of the SERS-active substrate reaches 6.06 × 10(6) , and the EF of the SERS sensor is about 4 times lower due to the influence of the PDMS cap. However, the sensor shows much higher measurement repeatability than the open substrate, and it reduces the sample preparation time from several hours to a few minutes, which makes the device more reliable and facile for trace chemical and biological analysis. PMID:23606301

  13. Non-hypoxic activation of the negative regulatory feedback loop of prolyl-hydroxylase oxygen sensors.

    PubMed

    Tug, Suzan; Delos Reyes, Buena; Fandrey, Joachim; Berchner-Pfannschmidt, Utta

    2009-07-10

    Hypoxia inducible factors (HIF) coordinate cellular responses towards hypoxia. HIFs are mainly regulated by a group of prolyl-hydroxylases (PHDs) that in the presence of oxygen, target the HIFalpha subunit for degradation. Herein, we studied the role of nitric oxide (NO) in regulating PHD activities under normoxic conditions. In the present study we show that different NO-donors initially inhibited endogenous PHD2 activity which led to accumulation of HIF-1alpha subsequently to enhance HIF-1 dependent increased PHD2 promoter activity. Consequently PHD2 abundance and activity were strongly induced which caused downregulation of HIF-1alpha. Interestingly, upregulation of endogenous PHD2 activity by NO was not found in cells that lack an intact pVHL dependent degradation pathway. Recovery of PHD activity required intact cells and was not observed in cell extracts or recombinant PHD2. In conclusion induction of endogenous PHD2 activity by NO is dependent on a feedback loop initiated despite normoxic conditions. PMID:19427832

  14. A multifrequency evaluation of active and passive microwave sensors for oil spill detection and assessment

    NASA Technical Reports Server (NTRS)

    Fenner, R. G.; Reid, S. C.; Solie, C. H.

    1980-01-01

    An evaluation is given of how active and passive microwave sensors can best be used in oil spill detection and assessment. Radar backscatter curves taken over oil spills are presented and their effect on synthetic aperture radar (SAR) imagery are discussed. Plots of microwave radiometric brightness variations over oil spills are presented and discussed. Recommendations as to how to select the best combination of frequency, viewing angle, and sensor type for evaluation of various aspects of oil spills are also discussed.

  15. Carbon nanofiber multiplexed array and Wireless Instantaneous Neurotransmitter Concentration Sensor for simultaneous detection of dissolved oxygen and dopamine

    PubMed Central

    Marsh, Michael P.; Koehne, Jessica E.; Andrews, Russell J.; Meyyappan, M.; Bennet, Kevin E.; Lee, Kendall H.

    2014-01-01

    Purpose While the mechanism of Deep Brain Stimulation (DBS) remains poorly understood, previous studies have shown that it evokes release of neurochemicals and induces activation of functional magnetic resonance imaging (fMRI) blood oxygen level-dependent signal in distinct areas of the brain. Therefore, the main purpose of this paper is to demonstrate the capabilities of the Wireless Instantaneous Neurotransmitter Concentration Sensor system (WINCS) in conjunction with a carbon nanofiber (CNF) multiplexed array electrode as a powerful tool for elucidating the mechanism of DBS through the simultaneous detection of multiple bioactive-molecules. Methods Patterned CNF nanoelectrode arrays were prepared on a 4-inch silicon wafer where each device consists of 3 × 3 electrode pads, 200 μm square, that contain CNFs spaced at 1μm intervals. The multiplexed carbon nanofiber CNF electrodes were integrated with WINCS to detect mixtures of dopamine (DA) and oxygen (O2) using fast scan cyclic voltammetry (FSCV) in vitro. Results First, simultaneous detection of O2 at two spatially different locations, 200 um apart, was demonstrated. Second, simultaneous detection of both O2 and DA at two spatially different locations, using two different decoupled waveforms was demonstrated. Third, controlled studies demonstrated that the waveform must be interleaved to avoid electrode crosstalk artifacts in the acquired data. Conclusions Multiplexed CNF nanoelectrode arrays for electrochemical detection of neurotransmitters show promise for the detection of multiple analytes with the application of time independent decoupled waveforms. Electrochemistry on CNF electrodes may be helpful in elucidating the mechanism of DBS, and may also provide the precision and sensitivity required for future applications in feedback modulated DBS neural control systems. PMID:24688800

  16. Characterization of a globin-coupled oxygen sensor with a gene-regulating function.

    PubMed

    Thijs, Liesbet; Vinck, Evi; Bolli, Alessandro; Trandafir, Florin; Wan, Xuehua; Hoogewijs, David; Coletta, Massimiliano; Fago, Angela; Weber, Roy E; Van Doorslaer, Sabine; Ascenzi, Paolo; Alam, Maqsudul; Moens, Luc; Dewilde, Sylvia

    2007-12-28

    Globin-coupled sensors (GCSs) are multiple-domain transducers, consisting of a regulatory globin-like heme-binding domain and a linked transducer domain(s). GCSs have been described in both Archaea and bacteria. They are generally assumed to bind O(2) (and perhaps other gaseous ligands) and to transmit a conformational change signal through the transducer domain in response to fluctuating O(2) levels. In this study, the heme-binding domain, AvGReg178, and the full protein, AvGReg of the Azotobacter vinelandii GCS, were cloned, expressed, and purified. After purification, the heme iron of AvGReg178 was found to bind O(2). This form was stable over many hours. In contrast, the predominant presence of a bis-histidine coordinate heme in ferric AvGReg was revealed. Differences in the heme pocket structure were also observed for the deoxygenated ferrous state of these proteins. The spectra showed that the deoxygenated ferrous derivatives of AvGReg178 and AvGReg are characterized by a penta-coordinate and hexa-coordinate heme iron, respectively. O(2) binding isotherms indicate that AvGReg178 and AvGReg show a high affinity for O(2) with P(50) values at 20 degrees C of 0.04 and 0.15 torr, respectively. Kinetics of CO binding indicate that AvGReg178 carbonylation conforms to a monophasic process, comparable with that of myoglobin, whereas AvGReg carbonylation conforms to a three-phasic reaction, as observed for several proteins with bis-histidine heme iron coordination. Besides sensing ligands, in vitro data suggest that AvGReg(178) may have a role in O(2)-mediated NO-detoxification, yielding metAvGReg(178) and nitrate. PMID:17925395

  17. Fiber optic oxygen sensor using fluorescence quenching for aircraft inerting fuel tank applications

    NASA Astrophysics Data System (ADS)

    Panahi, Allen

    2009-05-01

    On July 18, 2008, the FAA mandated that new aircraft are to include inerting technology to significantly reduce the potential for flammable vapor spaces in center wing fuel tanks. All passenger aircraft constructed since 1991 must also be retrofitted with this technology. This ruling is the result of 18 aircraft that have experienced fuel tank flammable vapor ignition incidents since 1960. Included in these are the TWA 800 and Avianca Flight 203 incidents that resulted in 337 total fatalities. Comprised of heavier hydrocarbon components, jet fuel is much less volatile, with Jet A having a flash point of approximately 100°F and JP-4 having a flash point of approximately 0°F. In contrast, straight-run gasoline has a flash point of approximately -40°F. The flash point is the minimum temperature where a liquid fuel can generate enough vapor to form a flammable mixture with air. If the temperature is below the flash point there isn't enough fuel evaporating to form a flammable fuel-air mixture. Since jet fuel and gasoline have similar flammable concentration limits, gasoline must produce much more vapor at a given temperature to have such a low flash point; hence gasoline is much more volatile than jet fuel. In this paper we explore Fluorescence Technology as applied to the design and development of O2 sensors that can be used for this application and discuss the various test and measurement techniques used to estimate the O2 gas concentration. We compare the various intensity based approaches and contrast them with the frequency domain techniques that measure phase to extract fluorescent lifetimes. The various inerting fuel tank requirements are explained and finally a novel compact measurement system using that uses the frequency heterodyning cross correlation technique that can be used for various applications is described in detail while the benefits are explored together with some test data collected.

  18. Estimating the oxygenated zone beneath building foundations for petroleum vapor intrusion assessment.

    PubMed

    Verginelli, Iason; Yao, Yijun; Wang, Yue; Ma, Jie; Suuberg, Eric M

    2016-07-15

    Previous studies show that aerobic biodegradation can effectively reduce hydrocarbon soil gas concentrations by orders of magnitude. Increasingly, oxygen limited biodegradation is being included in petroleum vapor intrusion (PVI) guidance for risk assessment at leaking underground storage tank sites. The application of PVI risk screening tools is aided by the knowledge of subslab oxygen conditions, which, however, are not commonly measured during site investigations. Here we introduce an algebraically explicit analytical method that can estimate oxygen conditions beneath the building slab, for PVI scenarios with impervious or pervious building foundations. Simulation results by this new model are then used to illustrate the role of site-specific conditions in determining the oxygen replenishment below the building for both scenarios. Furthermore, critical slab-width-to-source-depth ratios and critical source depths for the establishment of a subslab "oxygen shadow" (i.e. anoxic zone below the building) are provided as a function of key parameters such as vapor source concentration, effective diffusion coefficients of concrete and building depth. For impervious slab scenarios the obtained results are shown in good agreement with findings by previous studies and further support the recommendation by U.S. EPA about the inapplicability of vertical exclusion distances for scenarios involving large buildings and high source concentrations. For pervious slabs, results by this new model indicate that even relatively low effective diffusion coefficients of concrete can facilitate the oxygen transport into the subsurface below the building and create oxygenated conditions below the whole slab foundation favorable for petroleum vapor biodegradation. PMID:27016669

  19. Long-term in vivo experience of an electrochemical sensor using the potential step technique for measurement of mixed venous oxygen pressure.

    PubMed

    Holmström, N; Nilsson, P; Carlsten, J; Bowald, S

    1998-12-01

    An implantable amperometric blood oxygen sensor was developed to improve rate adaptation of heart pacemakers. Two different working electrode materials in direct contact with the blood were tested, smooth glassy carbon and gold. Reference electrodes of Ag/AgCl and porous pyrolytic carbon were evaluated. A counter electrode being the titanium housing of the pulse generator was partly coated with carbon. An implantable pacemaker system with chronocoulometric oxygen detection was developed. Heart synchronous potential steps were periodically applied to the 7.5 mm2 working electrode in the atrium. Both single and double potential step techniques were evaluated. The oxygen diffusion limited current was used to calculate the stimulation rate. Bench tests and studies on 31 animals were performed to evaluate long-term stability and biocompatibility. In five dogs, the AV node was destroyed by RF ablation to create a realistic animal model of a pacemaker patient. Sensor stability and response to exercise was followed up to a maximum implantation time of 4 years. Post-mortem examinations of the electrode surfaces and tissue response were performed. The results show that a gold electrode is more stable than glassy carbon. The Ag/AgCl reference was found not to be biocompatible, but activated carbon was stable enough for use as reference for the potentiostat. Double potential steps stabilize the sensor response in comparison to single steps. Blood protein adsorption on the gold surface decreased the oxygen transport but not the reaction efficacy. No adverse tissue reactions were observed. PMID:9883563

  20. Design and Characterization of a Sensorized Microfluidic Cell-Culture System with Electro-Thermal Micro-Pumps and Sensors for Cell Adhesion, Oxygen, and pH on a Glass Chip

    PubMed Central

    Bonk, Sebastian M.; Stubbe, Marco; Buehler, Sebastian M.; Tautorat, Carsten; Baumann, Werner; Klinkenberg, Ernst-Dieter; Gimsa, Jan

    2015-01-01

    We combined a multi-sensor glass-chip with a microfluidic channel grid for the characterization of cellular behavior. The grid was imprinted in poly-dimethyl-siloxane. Mouse-embryonal/fetal calvaria fibroblasts (MC3T3-E1) were used as a model system. Thin-film platinum (Pt) sensors for respiration (amperometric oxygen electrode), acidification (potentiometric pH electrodes) and cell adhesion (interdigitated-electrodes structures, IDES) allowed us to monitor cell-physiological parameters as well as the cell-spreading behavior. Two on-chip electro-thermal micro-pumps (ETμPs) permitted the induction of medium flow in the system, e.g., for medium mixing and drug delivery. The glass-wafer technology ensured the microscopic observability of the on-chip cell culture. Connecting Pt structures were passivated by a 1.2 μm layer of silicon nitride (Si3N4). Thin Si3N4 layers (20 nm or 60 nm) were used as the sensitive material of the pH electrodes. These electrodes showed a linear behavior in the pH range from 4 to 9, with a sensitivity of up to 39 mV per pH step. The oxygen sensors were circular Pt electrodes with a sensor area of 78.5 μm2. Their sensitivity was 100 pA per 1% oxygen increase in the range from 0% to 21% oxygen (air saturated). Two different IDES geometries with 30- and 50-μm finger spacings showed comparable sensitivities in detecting the proliferation rate of MC3T3 cells. These cells were cultured for 11 days in vitro to test the biocompatibility, microfluidics and electric sensors of our system under standard laboratory conditions. PMID:26263849

  1. ZigBee-based wireless multi-sensor system for physical activity assessment.

    PubMed

    Mo, Lingfei; Liu, Shaopeng; Gao, Robert X; John, Dinesh; Staudenmayer, John; Freedson, Patty

    2011-01-01

    Physical activity (PA) is important for assessing human exposure to the environment. This paper presents a ZigBee-based Wireless wearable multi-sensor Integrated Measurement System (WIMS) for in-situ PA measurement. Two accelerometers, a piezoelectric displacement sensor, and an ultraviolet (UV) sensor have been used for the physical activity assessment. Detailed analysis was performed for the hardware design and embedded program control, enabling efficient data sampling and transmission, compact design, and extended battery life to meet requirements for PA assessment under free-living conditions. Preliminary testing of the WIMS has demonstrated the functionality of the design, while performance comparison of the WIMS with a wired version on an electromagnetic shaker has demonstrated the signal validity. PMID:22254443

  2. Factors affecting the performance of a single-chamber microbial fuel cell-type biological oxygen demand sensor.

    PubMed

    Yang, Gai-Xiu; Sun, Yong-Ming; Kong, Xiao-Ying; Zhen, Feng; Li, Ying; Li, Lian-Hua; Lei, Ting-Zhou; Yuan, Zhen-Hong; Chen, Guan-Yi

    2013-01-01

    Microbial fuel cells (MFCs) are devices that exploit microorganisms as biocatalysts to degrade organic matter or sludge present in wastewater (WW), and thereby generate electricity. We developed a simple, low-cost single-chamber microbial fuel cell (SCMFC)-type biochemical oxygen demand (BOD) sensor using carbon felt (anode) and activated sludge, and demonstrated its feasibility in the construction of a real-time BOD measurement system. Further, the effects of anodic pH and organic concentration on SCMFC performance were examined, and the correlation between BOD concentration and its response time was analyzed. Our results demonstrated that the SCMFC exhibited a stable voltage after 132 min following the addition of synthetic WW (BOD concentration: 200 mg/L). Notably, the response signal increased with an increase in BOD concentration (range: 5-200 mg/L) and was found to be directly proportional to the substrate concentration. However, at higher BOD concentrations (>120 mg/L) the response signal remained unaltered. Furthermore, we optimized the SCMFC using synthetic WW, and tested it with real WW. Upon feeding real WW, the BOD values exhibited a standard deviation from 2.08 to 8.3% when compared to the standard BOD5 method, thus demonstrating the practical applicability of the developed system to real treatment effluents. PMID:24225089

  3. An intracellular redox sensor for reactive oxygen species at the M3-M4 linker of GABAAρ1 receptors

    PubMed Central

    Beltrán González, Andrea N; Gasulla, Javier; Calvo, Daniel J

    2014-01-01

    Background and Purpose Reactive oxygen species (ROS) are normally involved in cell oxidative stress but also play a role as cellular messengers in redox signalling; for example, modulating the activity of neurotransmitter receptors and ion channels. However, the direct actions of ROS on GABAA receptors were not previously demonstrated. In the present work, we studied the effects of ROS on GABAAρ1 receptor function. Experimental Approach GABAAρ1 receptors were expressed in oocytes and GABA-evoked responses electrophysiologically recorded in the presence or absence of ROS. Chemical protection of cysteines by selective sulfhydryl reagents and site-directed mutagenesis studies were used to identify protein residues involved in ROS actions. Key Results GABAAρ1 receptor-mediated responses were significantly enhanced in a concentration-dependent and reversible manner by H2O2. Potentiating effects were attenuated by a free radical scavenger, lipoic acid or an inhibitor of the Fenton reaction, deferoxamine. Each ρ1 subunit contains only three cysteine residues, two extracellular at the Cys-loop (C177 and C191) and one intracellular (C364) at the M3-M4 linker. Mutant GABAAρ1 receptors in which C364 was exchanged by alanine were completely insensitive to modulation, implying that this site, rather than a cysteine in the Cys-loop, is essential for ROS modulation. Conclusion and Implications Our results show that the function of GABAAρ1 receptors is enhanced by ROS and that the intracellular C364 is the sensor for ROS actions. PMID:24428763

  4. Fan Performance Testing and Oxygen Compatibility Assessment Results for Future Space Suit Life Support Systems

    NASA Technical Reports Server (NTRS)

    Jennings, Mallory A.; Paul, Heather L.; Vogel, Matthew

    2008-01-01

    An advanced portable life support system (PLSS) for the space suit will require a small, robust, and energy-efficient system to transport the ventilation gas through the space suit for lunar Extravehicular Activity (EVA) operations. A trade study identified and compared ventilation transport technologies in commercial, military, and space applications to determine which technologies could be adapted for EVA use. Based on the trade study results, five commercially available, 24volt fans were selected for performance testing at various pressures and flow rates. Measured fan parameters included fan delta-pressures, input voltages, input electrical currents, and in some cases motor windings electrical voltages and currents. In addition, a follow-on trade study was performed to identify oxygen compatibility issues and assess their impact on fan design. This paper outlines the results of the fan performance characterization testing, as well as the results from the oxygen compatibility assessment.

  5. Fan Performance Testing and Oxygen Compatibility Assessment Results for Future Space Suit Life Support Systems

    NASA Technical Reports Server (NTRS)

    Paul, Heather L.; Jennings, Mallory A.; Vogel, Matthew

    2009-01-01

    An advanced portable life support system (PLSS) for the space suit will require a small, robust, and energyefficient system to transport the ventilation gas through the space suit for lunar Extravehicular Activity (EVA) operations. A trade study identified and compared ventilation transport technologies in commercial, military, and space applications to determine which technologies could be adapted for EVA use. Based on the trade study results, five commercially available, 24-volt fans were selected for performance testing at various pressures and flow rates. Measured fan parameters included fan delta-pressures, input voltages, input electrical currents, and in some cases motor windings electrical voltages and currents. In addition, a follow-on trade study was performed to identify oxygen compatibility issues and assess their impact on fan design. This paper outlines the results of the fan performance characterization testing, as well as the results from the oxygen compatibility assessment.

  6. Micro-encapsulated sensors for in vivo assessment of the oxidative stress in aquatic organisms

    NASA Astrophysics Data System (ADS)

    Sadovoy, Anton; Teh, Cathleen; Escobar, Marco; Meglinski, Igor; Korzh, Vladimir

    2011-10-01

    Oxidative stress results from an imbalance between the production and detoxification of reactive oxygen spices (ROS). ROS are natural byproducts of normal metabolism of oxygen and have important roles in cell signaling and homeostasis. Many heart related diseases like heart failure and myocardial infarction develop as a result of oxidative stress. Current treatment cannot improve the progressive decline in heart function experienced by all patients. Therefore heart failure is the cause of around 25% of all deaths in the Asia Pacific region. Thus any step taken to address the oxidative stress problem is essential for enhancing human health and improve their quality of life. Current approach is dedicated to develop micron-size oxidation stress-sensor for in-vivo measuring level of ROS in KillerRed expressing transgenic zebrafish larvae. Central to our investigation is the light-inducible heart failure animal model we developed in zebrafish that expressed KillerRed in the heart. By utilizing the photosensitizer properties of KillerRed to produce ROS upon green light illumination, heart failure can be repeatedly induced in a non-invasive manner. Importantly, the use of this biological platform permits the development of physiologically sensitive ROS sensor and identifies efficient antioxidants that improve heart contractility. The biosensor approach is based on utilizing biocompatible polyelectrolyte microcapsules as a carry of fluorescent dyes sensitive to amount of reactive oxygen spices. Microcapsule prevents dye diffusion in tissue that makes use toxic dyes possible. Microcapsule's wall is permeable for environment with size less than 500 Da. The oxidation stress-sensors are injected directly in zebrafish pericardium with further circulation along blood system. Detecting of ROS is obtained by using laser scanning microscopy by illuminating oxidation stress-sensors and detecting changing excitation signal from the fluorescent dye.

  7. Micro-encapsulated sensors for in vivo assessment of the oxidative stress in aquatic organisms

    NASA Astrophysics Data System (ADS)

    Sadovoy, Anton; Teh, Cathleen; Escobar, Marco; Meglinski, Igor; Korzh, Vladimir

    2012-03-01

    Oxidative stress results from an imbalance between the production and detoxification of reactive oxygen spices (ROS). ROS are natural byproducts of normal metabolism of oxygen and have important roles in cell signaling and homeostasis. Many heart related diseases like heart failure and myocardial infarction develop as a result of oxidative stress. Current treatment cannot improve the progressive decline in heart function experienced by all patients. Therefore heart failure is the cause of around 25% of all deaths in the Asia Pacific region. Thus any step taken to address the oxidative stress problem is essential for enhancing human health and improve their quality of life. Current approach is dedicated to develop micron-size oxidation stress-sensor for in-vivo measuring level of ROS in KillerRed expressing transgenic zebrafish larvae. Central to our investigation is the light-inducible heart failure animal model we developed in zebrafish that expressed KillerRed in the heart. By utilizing the photosensitizer properties of KillerRed to produce ROS upon green light illumination, heart failure can be repeatedly induced in a non-invasive manner. Importantly, the use of this biological platform permits the development of physiologically sensitive ROS sensor and identifies efficient antioxidants that improve heart contractility. The biosensor approach is based on utilizing biocompatible polyelectrolyte microcapsules as a carry of fluorescent dyes sensitive to amount of reactive oxygen spices. Microcapsule prevents dye diffusion in tissue that makes use toxic dyes possible. Microcapsule's wall is permeable for environment with size less than 500 Da. The oxidation stress-sensors are injected directly in zebrafish pericardium with further circulation along blood system. Detecting of ROS is obtained by using laser scanning microscopy by illuminating oxidation stress-sensors and detecting changing excitation signal from the fluorescent dye.

  8. In vitro and in vivo studies of new photoluminescent oxygen sensors for non-invasive intravascular pO2 measurements

    NASA Astrophysics Data System (ADS)

    Nowak-Sliwinska, Patrycja; Forte, Eddy; van den Bergh, Hubert; Wagnières, Georges

    2009-06-01

    The concentration of oxygen and its rate of consumption are important factors playing a role in PDT and radiotherapy. One of the methods for measuring the tissular oxygen partial pressure (pO2) is based on the use of luminophores presenting an oxygen-dependent quenching of their phosphorescence. The time-resolved luminescence spectroscopy of palladium (PdTCPP) or ruthenium (RuDPP) porphyrin complexes is used for this purpose. Unfortunately, these porphyrin derivatives are phototoxic and leak rapidly out of the blood vessels, making them unsuitable for measuring tissular and or intravascular pO2. Therefore, this research aimed at developing and testing new biocompatible, non-phototoxic oxygen sensors based on palladium complexes incorporated into oxygen permeable, polysaccharide-based nanoparticles appropriate for noninvasive in situ and in vivo measurements of the pO2. In vitro studies, performed with an optical fiber-based time-resolved spectrophotometer, showed that the incorporation of such pO2 probes in nanovectors reduces their sensitivity to oxygen as well as their photobleaching by less than one order of magnitude. However, in vivo biocompatibility studies performed on the chick's embryo chorioallantoic membrane (CAM) model demonstrated that the luminescence of those oxygen probes tends to be heterogeneously distributed within the vasculature. In addition, these probes induce a 'clumping tendency', resulting in a more or less decreased viability of the embryos.

  9. The Relationship between Clinical, Momentary, and Sensor-based Assessment of Depression

    PubMed Central

    Saeb, Sohrab; Zhang, Mi; Kwasny, Mary M.; Karr, Christopher J.; Kording, Konrad; Mohr, David C.

    2015-01-01

    The clinical assessment of severity of depressive symptoms is commonly performed with standardized self-report questionnaires, most notably the patient health questionnaire (PHQ-9), which are usually administered in a clinic. These questionnaires evaluate symptoms that are stable over time. Ecological momentary assessment (EMA) methods, on the other hand, acquire patient ratings of symptoms in the context of their lives. Today’s smartphones allow us to also obtain objective contextual information, such as the GPS location, that may also be related to depression. Considering clinical PHQ-9 scores as ground truth, an interesting question is to what extent the EMA ratings and contextual sensor data can be used as potential predictors of depression. To answer this question, we obtained PHQ-9 scores from 18 participants with a variety of depressive symptoms in our lab, and then collected their EMA and GPS sensor data using their smartphones over a period of two weeks. We analyzed the relationship between GPS sensor features, EMA ratings, and the PHQ-9 scores. While we found a strong correlation between a number of sensor features extracted from the two-week period and the PHQ-9 scores, the other relationships remained non-significant. Our results suggest that depression is better evaluated using long-term sensor-based measurements than the momentary ratings of mental state or short-term sensor information. PMID:26640739

  10. The damage assessment methodology in cooperation with smart sensors and inspection robots

    NASA Astrophysics Data System (ADS)

    Nitta, Yoshihiro; Ishida, Masami; Onai, Toshio; Watakabe, Morimasa; Nishitani, Akira; Matsui, Chisa

    2014-03-01

    This paper proposes a damage assessment methodology for the non-structural elements, especially the ceiling, in cooperation with the smart sensors and the inspection blimp robot with the Wi-Fi camera. The developed smart sensors use the infrared LEDs in sending the measured data to the inspection blimp robot. The inspection blimp robot integrated in the proposed system has a Wi-Fi camera and an infrared remote control receiver for receiving the data from the smart sensor. In the proposed methodology, the distributed smart sensors firstly detect the damage occurrence. Next, the inspection blimp robots can gather the data from the smart sensors, which transmit the measured data by using an infrared remote control receiver and LED signals. The inspection blimp robot also can inspect the damage location and captures the photographic image of the damage condition. The inspection blimp robot will be able to estimate the damage condition without any process of engineers' on-site-inspection involved. To demonstrate the effectiveness of the inspection blimp robot, the blimp robot is utilized to estimate the aging ceiling of a real structure. For demonstrating the feasibility or possibility of the proposed damage assessment methodology in cooperation with the smart sensors and the inspection blimp robot, the conceptual laboratory experiment is conducted. The proposed methodology will provide valuable information for the repair and maintenance decision making of a damaged structure.

  11. Laboratory validation of MEMS-based sensors for post-earthquake damage assessment image

    NASA Astrophysics Data System (ADS)

    Pozzi, Matteo; Zonta, Daniele; Santana, Juan; Colin, Mikael; Saillen, Nicolas; Torfs, Tom; Amditis, Angelos; Bimpas, Matthaios; Stratakos, Yorgos; Ulieru, Dumitru; Bairaktaris, Dimitirs; Frondistou-Yannas, Stamatia; Kalidromitis, Vasilis

    2011-04-01

    The evaluation of seismic damage is today almost exclusively based on visual inspection, as building owners are generally reluctant to install permanent sensing systems, due to their high installation, management and maintenance costs. To overcome this limitation, the EU-funded MEMSCON project aims to produce small size sensing nodes for measurement of strain and acceleration, integrating Micro-Electro-Mechanical Systems (MEMS) based sensors and Radio Frequency Identification (RFID) tags in a single package that will be attached to reinforced concrete buildings. To reduce the impact of installation and management, data will be transmitted to a remote base station using a wireless interface. During the project, sensor prototypes were produced by assembling pre-existing components and by developing ex-novo miniature devices with ultra-low power consumption and sensing performance beyond that offered by sensors available on the market. The paper outlines the device operating principles, production scheme and working at both unit and network levels. It also reports on validation campaigns conducted in the laboratory to assess system performance. Accelerometer sensors were tested on a reduced scale metal frame mounted on a shaking table, back to back with reference devices, while strain sensors were embedded in both reduced and full-scale reinforced concrete specimens undergoing increasing deformation cycles up to extensive damage and collapse. The paper assesses the economical sustainability and performance of the sensors developed for the project and discusses their applicability to long-term seismic monitoring.

  12. Nitrate and Nitrite Variability at the Seafloor of an Oxygen Minimum Zone Revealed by a Novel Microfluidic In-Situ Chemical Sensor.

    PubMed

    Yücel, Mustafa; Beaton, Alexander D; Dengler, Marcus; Mowlem, Matthew C; Sohl, Frank; Sommer, Stefan

    2015-01-01

    Microfluidics, or lab-on-a-chip (LOC) is a promising technology that allows the development of miniaturized chemical sensors. In contrast to the surging interest in biomedical sciences, the utilization of LOC sensors in aquatic sciences is still in infancy but a wider use of such sensors could mitigate the undersampling problem of ocean biogeochemical processes. Here we describe the first underwater test of a novel LOC sensor to obtain in situ calibrated time-series (up to 40 h) of nitrate+nitrite (ΣNOx) and nitrite on the seafloor of the Mauritanian oxygen minimum zone, offshore Western Africa. Initial tests showed that the sensor successfully reproduced water column (160 m) nutrient profiles. Lander deployments at 50, 100 and 170 m depth indicated that the biogeochemical variability was high over the Mauritanian shelf: The 50 m site had the lowest ΣNOx concentration, with 15.2 to 23.4 μM (median=18.3 μM); while at the 100 site ΣNOx varied between 21.0 and 30.1 μM over 40 hours (median = 25.1 μM). The 170 m site had the highest median ΣNOx level (25.8 μM) with less variability (22.8 to 27.7 μM). At the 50 m site, nitrite concentration decreased fivefold from 1 to 0.2 μM in just 30 hours accompanied by decreasing oxygen and increasing nitrate concentrations. Taken together with the time series of oxygen, temperature, pressure and current velocities, we propose that the episodic intrusion of deeper waters via cross-shelf transport leads to intrusion of nitrate-rich, but oxygen-poor waters to shallower locations, with consequences for benthic nitrogen cycling. This first validation of an LOC sensor at elevated water depths revealed that when deployed for longer periods and as a part of a sensor network, LOC technology has the potential to contribute to the understanding of the benthic biogeochemical dynamics. PMID:26161958

  13. Nitrate and Nitrite Variability at the Seafloor of an Oxygen Minimum Zone Revealed by a Novel Microfluidic In-Situ Chemical Sensor

    PubMed Central

    Yücel, Mustafa; Beaton, Alexander D.; Dengler, Marcus; Mowlem, Matthew C.; Sohl, Frank; Sommer, Stefan

    2015-01-01

    Microfluidics, or lab-on-a-chip (LOC) is a promising technology that allows the development of miniaturized chemical sensors. In contrast to the surging interest in biomedical sciences, the utilization of LOC sensors in aquatic sciences is still in infancy but a wider use of such sensors could mitigate the undersampling problem of ocean biogeochemical processes. Here we describe the first underwater test of a novel LOC sensor to obtain in situ calibrated time-series (up to 40 h) of nitrate+nitrite (ΣNOx) and nitrite on the seafloor of the Mauritanian oxygen minimum zone, offshore Western Africa. Initial tests showed that the sensor successfully reproduced water column (160 m) nutrient profiles. Lander deployments at 50, 100 and 170 m depth indicated that the biogeochemical variability was high over the Mauritanian shelf: The 50 m site had the lowest ΣNOx concentration, with 15.2 to 23.4 μM (median=18.3 μM); while at the 100 site ΣNOx varied between 21.0 and 30.1 μM over 40 hours (median = 25.1μM). The 170 m site had the highest median ΣNOx level (25.8 μM) with less variability (22.8 to 27.7 μM). At the 50 m site, nitrite concentration decreased fivefold from 1 to 0.2 μM in just 30 hours accompanied by decreasing oxygen and increasing nitrate concentrations. Taken together with the time series of oxygen, temperature, pressure and current velocities, we propose that the episodic intrusion of deeper waters via cross-shelf transport leads to intrusion of nitrate-rich, but oxygen-poor waters to shallower locations, with consequences for benthic nitrogen cycling. This first validation of an LOC sensor at elevated water depths revealed that when deployed for longer periods and as a part of a sensor network, LOC technology has the potential to contribute to the understanding of the benthic biogeochemical dynamics. PMID:26161958

  14. Long-term performance of Aanderaa optodes and sea-bird SBE-43 dissolved-oxygen sensors bottom mounted at 32 m in Massachusetts Bay

    USGS Publications Warehouse

    Martini, Marinna; Butman, Bradford; Mickelson, Michael J.

    2007-01-01

    A field evaluation of two new dissolved-oxygen sensing technologies, the Aanderaa Instruments AS optode model 3830 and the Sea-Bird Electronics, Inc., model SBE43, was carried out at about 32-m water depth in western Massachusetts Bay. The optode is an optical sensor that measures fluorescence quenching by oxygen molecules, while the SBE43 is a Clark polarographic membrane sensor. Optodes were continuously deployed on bottom tripod frames by exchanging sensors every 4 months over a 19-month period. A Sea-Bird SBE43 was added during one 4-month deployment. These moored observations compared well with oxygen measurements from profiles collected during monthly shipboard surveys conducted by the Massachusetts Water Resources Authority. The mean correlation coefficient between the moored measurements and shipboard survey data was >0.9, the mean difference was 0.06 mL L−1, and the standard deviation of the difference was 0.15 mL L−1. The correlation coefficient between the optode and the SBE43 was >0.9 and the mean difference was 0.07 mL L−1. Optode measurements degraded when fouling was severe enough to block oxygen molecules from entering the sensing foil over a significant portion of the sensing window. Drift observed in two optodes beginning at about 225 and 390 days of deployment is attributed to degradation of the sensing foil. Flushing is necessary to equilibrate the Sea-Bird sensor. Power consumption by the SBE43 and required pump was 19.2 mWh per sample, and the optode consumed 0.9 mWh per sample, both within expected values based on manufacturers’ specifications.

  15. A PAS domain with an oxygen labile [4Fe-4S](2+) cluster in the oxygen sensor kinase NreB of Staphylococcus carnosus.

    PubMed

    Müllner, Martin; Hammel, Oliver; Mienert, Bernd; Schlag, Steffen; Bill, Eckhard; Unden, Gottfried

    2008-12-30

    The cytoplasmic histidine sensor kinase NreB of Staphylococcus carnosus responds to O(2) and controls together with the response regulator NreC the expression of genes of nitrate/nitrite respiration. nreBC homologous genes were found in Staphylococcus strains and Bacillus clausii, and a modified form was found in some Lactobacillus strains. NreB contains a sensory domain with similarity to heme B binding PAS domains. Anaerobically prepared NreB of S. carnosus exhibited a (diamagnetic) [4Fe-4S](2+) cluster when assessed by Mossbauer spectroscopy. Upon reaction with air, the cluster was degraded with a half-life of approximately 2.5 min. No significant amounts of Mossbauer or EPR detectable intermediates were found during the decay, but magnetic Mossbauer spectra revealed formation of diamagnetic [2Fe-2S](2+) clusters. After extended exposure to air, NreB was devoid of a FeS cluster. Photoreduction with deazaflavin produced small amounts of [4Fe-4S](+), which were degraded subsequently. The magnetically perturbed Mossbauer spectrum of the [4Fe-4S](2+) cluster corroborated the S = 0 spin state and revealed uniform electric field gradient tensors of the iron sites, suggesting full delocalization of the valence electrons and binding of each of the Fe ions by four S ligands, including the ligand to the protein. Mutation of each of the four Cys residues inactivated NreB function in vivo in accordance with their role as ligands. [4Fe-4S](2+) cluster-containing NreB had high kinase activity. Exposure to air decreased the kinase activity and content of the [4Fe-4S](2+) cluster with similar half-lives. We conclude that the sensory domain of NreB represents a new type of PAS domain containing a [4Fe-4S](2+) cluster for sensing and function. PMID:19102705

  16. A Limiting Current Oxygen Sensor Based on LSGM as a Solid Electrolyte and LSGMN ( N = Fe, Co) as a Dense Diffusion Barrier

    NASA Astrophysics Data System (ADS)

    Liu, Tao; Gao, Xiang; He, Bei-Gang; Yu, Jing-Kun

    2016-07-01

    The La0.8Sr0.2(Ga1- x Co x )0.8Mg0.2O3- δ (LSGMC x = 0.05, 0.1, 0.15, 0.2, 0.25) and La0.8Sr0.2(Ga1- x Fe x )0.8Mg0.2O3- δ (LSGMF x = 0.1, 0.2, 0.3) samples were prepared by solid-state reaction. The structure, conductivity, thermal expansion behavior, and chemical compatibility were studied by XRD, dilatometry, and four-terminal method. A limiting current oxygen sensor was prepared with La0.8Sr0.2Ga0.83Mg0.17O2.815 as a solid electrolyte and La0.8Sr0.2(Ga0.75Co0.25)0.8Mg0.2O3- δ as a dense diffusion barrier. The oxygen-sensitive characteristic was measured at different oxygen concentrations. The results show that the phase structure of samples is cubic, except La0.8Sr0.2(Ga0.75Co0.25)0.8Mg0.2O3- δ , which has a hexagonal structure. The change in activation energy for electrical conductivity and the increase in thermal expansion coefficient are confirmed to correlate with an increasing concentration of oxygen vacancies. The limiting current oxygen sensor exhibits a good limiting current platform and the limiting current depends linearly on the oxygen concentration: I L(mA) = 12.8519 + 2.2667 x_{{{O}_{{2}} }} (mol%, 0 < x_{{{{O}}_{ 2} }} < 3.31) at 750 °C, I L(mA) = 14.3222 + 3.5180 x_{{{O}_{{2}} }} (mol%, 0 < x_{{{{O}}_{ 2} }} < 4.16) at 800 °C, and I L(mA) = 15.2872 + 5.0269x_{{{O}_{{2}} }}(mol%, 0 < x_{{{{O}}_{ 2} }} < 4.12) at 850 °C. The sensor has the best sensitivity at 850 °C. As the oxygen concentration increases, the interface resistance of the sensor decreases at 850 °C.

  17. A Limiting Current Oxygen Sensor Based on LSGM as a Solid Electrolyte and LSGMN (N = Fe, Co) as a Dense Diffusion Barrier

    NASA Astrophysics Data System (ADS)

    Liu, Tao; Gao, Xiang; He, Bei-Gang; Yu, Jing-Kun

    2016-06-01

    The La0.8Sr0.2(Ga1-x Co x )0.8Mg0.2O3-δ (LSGMC x = 0.05, 0.1, 0.15, 0.2, 0.25) and La0.8Sr0.2(Ga1-x Fe x )0.8Mg0.2O3-δ (LSGMF x = 0.1, 0.2, 0.3) samples were prepared by solid-state reaction. The structure, conductivity, thermal expansion behavior, and chemical compatibility were studied by XRD, dilatometry, and four-terminal method. A limiting current oxygen sensor was prepared with La0.8Sr0.2Ga0.83Mg0.17O2.815 as a solid electrolyte and La0.8Sr0.2(Ga0.75Co0.25)0.8Mg0.2O3-δ as a dense diffusion barrier. The oxygen-sensitive characteristic was measured at different oxygen concentrations. The results show that the phase structure of samples is cubic, except La0.8Sr0.2(Ga0.75Co0.25)0.8Mg0.2O3-δ , which has a hexagonal structure. The change in activation energy for electrical conductivity and the increase in thermal expansion coefficient are confirmed to correlate with an increasing concentration of oxygen vacancies. The limiting current oxygen sensor exhibits a good limiting current platform and the limiting current depends linearly on the oxygen concentration: I L(mA) = 12.8519 + 2.2667 x_{{{O}_{{2}} }} (mol%, 0 < x_{{{{O}}_{ 2} }} < 3.31) at 750 °C, I L(mA) = 14.3222 + 3.5180 x_{{{O}_{{2}} }} (mol%, 0 < x_{{{{O}}_{ 2} }} < 4.16) at 800 °C, and I L(mA) = 15.2872 + 5.0269x_{{{O}_{{2}} }} (mol%, 0 < x_{{{{O}}_{ 2} }} < 4.12) at 850 °C. The sensor has the best sensitivity at 850 °C. As the oxygen concentration increases, the interface resistance of the sensor decreases at 850 °C.

  18. Assessing sensor reliability for multisensor data fusion within the transferable belief model.

    PubMed

    Elouedi, Zied; Mellouli, Khaled; Smets, Philippe

    2004-02-01

    This paper presents a method for assessing the reliability of a sensor in a classification problem based on the transferable belief model. First, we develop a method for the evaluation of the reliability of a sensor when considered alone. The method is based on finding the discounting factor minimizing the distance between the pignistic probabilities computed from the discounted beliefs and the actual values of data. Next, we develop a method for assessing the reliability of several sensors that are supposed to work jointly and their readings are aggregated. The discounting factors are computed on the basis of minimizing the distance between the pignistic probabilities computed from the combined discounted belief functions and the actual values of data. PMID:15369123

  19. Turbine rotor disk health monitoring assessment based on sensor technology and spin tests data.

    PubMed

    Abdul-Aziz, Ali; Woike, Mark

    2013-01-01

    The paper focuses on presenting data obtained from spin test experiments of a turbine engine like rotor disk and assessing their correlation to the development of a structural health monitoring and fault detection system. The data were obtained under various operating conditions such as the rotor disk being artificially induced with and without a notch and rotated at a rotational speed of up to 10,000 rpm under balanced and imbalanced state. The data collected included blade tip clearance, blade tip timing measurements, and shaft displacements. Two different sensor technologies were employed in the testing: microwave and capacitive sensors, respectively. The experimental tests were conducted at the NASA Glenn Research Center's Rotordynamics Laboratory using a high precision spin system. Disk flaw observations and related assessments from the collected data for both sensors are reported and discussed. PMID:23844396

  20. Turbine Rotor Disk Health Monitoring Assessment Based on Sensor Technology and Spin Tests Data

    PubMed Central

    2013-01-01

    The paper focuses on presenting data obtained from spin test experiments of a turbine engine like rotor disk and assessing their correlation to the development of a structural health monitoring and fault detection system. The data were obtained under various operating conditions such as the rotor disk being artificially induced with and without a notch and rotated at a rotational speed of up to 10,000 rpm under balanced and imbalanced state. The data collected included blade tip clearance, blade tip timing measurements, and shaft displacements. Two different sensor technologies were employed in the testing: microwave and capacitive sensors, respectively. The experimental tests were conducted at the NASA Glenn Research Center's Rotordynamics Laboratory using a high precision spin system. Disk flaw observations and related assessments from the collected data for both sensors are reported and discussed. PMID:23844396

  1. Integration of Grid and Sensor Web for Flood Monitoring and Risk Assessment from Heterogeneous Data

    NASA Astrophysics Data System (ADS)

    Kussul, Nataliia; Skakun, Sergii; Shelestov, Andrii

    2013-04-01

    Over last decades we have witnessed the upward global trend in natural disaster occurrence. Hydrological and meteorological disasters such as floods are the main contributors to this pattern. In recent years flood management has shifted from protection against floods to managing the risks of floods (the European Flood risk directive). In order to enable operational flood monitoring and assessment of flood risk, it is required to provide an infrastructure with standardized interfaces and services. Grid and Sensor Web can meet these requirements. In this paper we present a general approach to flood monitoring and risk assessment based on heterogeneous geospatial data acquired from multiple sources. To enable operational flood risk assessment integration of Grid and Sensor Web approaches is proposed [1]. Grid represents a distributed environment that integrates heterogeneous computing and storage resources administrated by multiple organizations. SensorWeb is an emerging paradigm for integrating heterogeneous satellite and in situ sensors and data systems into a common informational infrastructure that produces products on demand. The basic Sensor Web functionality includes sensor discovery, triggering events by observed or predicted conditions, remote data access and processing capabilities to generate and deliver data products. Sensor Web is governed by the set of standards, called Sensor Web Enablement (SWE), developed by the Open Geospatial Consortium (OGC). Different practical issues regarding integration of Sensor Web with Grids are discussed in the study. We show how the Sensor Web can benefit from using Grids and vice versa. For example, Sensor Web services such as SOS, SPS and SAS can benefit from the integration with the Grid platform like Globus Toolkit. The proposed approach is implemented within the Sensor Web framework for flood monitoring and risk assessment, and a case-study of exploiting this framework, namely the Namibia SensorWeb Pilot Project, is

  2. Second derivative multispectral algorithm for quantitative assessment of cutaneous tissue oxygenation

    NASA Astrophysics Data System (ADS)

    Huang, Jiwei; Zhang, Shiwu; Gnyawali, Surya; Sen, Chandan K.; Xu, Ronald X.

    2015-03-01

    We report a second derivative multispectral algorithm for quantitative assessment of cutaneous tissue oxygen saturation (StO2). The algorithm is based on a forward model of light transport in multilayered skin tissue and an inverse algorithm for StO2 reconstruction. Based on the forward simulation results, a parameter of a second derivative ratio (SDR) is derived as a function of cutaneous tissue StO2. The SDR function is optimized at a wavelength set of 544, 552, 568, 576, 592, and 600 nm so that cutaneous tissue StO2 can be derived with minimal artifacts by blood concentration, tissue scattering, and melanin concentration. The proposed multispectral StO2 imaging algorithm is verified in both benchtop and in vivo experiments. The experimental results show that the proposed multispectral imaging algorithm is able to map cutaneous tissue StO2 in high temporal resolution with reduced measurement artifacts induced by different skin conditions in comparison with other three commercial tissue oxygen measurement systems. These results indicate that the multispectral StO2 imaging technique has the potential for noninvasive and quantitative assessment of skin tissue oxygenation with a high temporal resolution.

  3. Second derivative multispectral algorithm for quantitative assessment of cutaneous tissue oxygenation

    PubMed Central

    Huang, Jiwei; Zhang, Shiwu; Gnyawali, Surya; Sen, Chandan K.; Xu, Ronald X.

    2015-01-01

    Abstract. We report a second derivative multispectral algorithm for quantitative assessment of cutaneous tissue oxygen saturation (StO2). The algorithm is based on a forward model of light transport in multilayered skin tissue and an inverse algorithm for StO2 reconstruction. Based on the forward simulation results, a parameter of a second derivative ratio (SDR) is derived as a function of cutaneous tissue StO2. The SDR function is optimized at a wavelength set of 544, 552, 568, 576, 592, and 600 nm so that cutaneous tissue StO2 can be derived with minimal artifacts by blood concentration, tissue scattering, and melanin concentration. The proposed multispectral StO2 imaging algorithm is verified in both benchtop and in vivo experiments. The experimental results show that the proposed multispectral imaging algorithm is able to map cutaneous tissue StO2 in high temporal resolution with reduced measurement artifacts induced by different skin conditions in comparison with other three commercial tissue oxygen measurement systems. These results indicate that the multispectral StO2 imaging technique has the potential for noninvasive and quantitative assessment of skin tissue oxygenation with a high temporal resolution. PMID:25734405

  4. Assessing spectral reflectance sensors for detecting N stress in corn

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Variable rate sidedress applications of fertilizers can often improve N use efficiency in corn. While variable rate fertilizer prescriptions may be produced from previous years’ yield and soils data, an assessment of the spatial variability of a crop’s N status just prior to fertilizer application ...

  5. The adequacy of oxygenation in COPD patients undergoing long-term oxygen therapy assessed by pulse oximetry at home.

    PubMed

    Sliwiński, P; Lagosz, M; Górecka, D; Zieliński, J

    1994-02-01

    It is probable that some daily activities may cause marked falls in arterial oxygen saturation (SaO2) in patients undergoing long-term oxygen therapy (LTOT), despite good oxygenation at rest. We estimated the adequacy of LTOT in 34 randomly selected chronic obstructive pulmonary disease (COPD) patients at home by monitoring SaO2 continuously over 24 h. The subjects were also asked to complete a questionnaire listing frequent daily activities. Despite almost normal mean SaO2 (94%) at the beginning of recording (O2 2 l.min-1, at rest) the subjects studied spent 6.9 h below an SaO2 of 90%, with minimum SaO2 of 61%. On average we observed 10 episodes of desaturation in each patient over 24 h, both while breathing air and oxygen. The comparison of SaO2 recordings and questionnaires revealed the highest number of desaturations during sleep, followed by naps, watching the television, eating, washing and talking. The oxygen flow rate prescribed, based on blood gas measurements at rest, did not protect 85% of the patients studied from deep falls in SaO2 during daily life. An increase oxygen flow during some activities and during sleep is suggested. PMID:8162980

  6. Comparison of active and passive optical sensors for assessment of plant nitrogen

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nitrogen (N) fertilizer has received attention for a long time as a potential source of ground water pollution. Considerable research has been conducted to investigate use of remote sensing for assessing plant N status to improve N use efficiency. Most of these studies have used passive type sensors...

  7. Advanced turbine systems sensors and controls needs assessment study. Final report

    SciTech Connect

    Anderson, R.L.; Fry, D.N.; McEvers, J.A.

    1997-02-01

    The Instrumentation and Controls Division of the Oak Ridge National Laboratory performed an assessment of the sensors and controls needs for land-based advanced gas turbines being designed as a part of the Department of Energy`s (DOE`s) Advanced Turbine Systems (ATS) Program for both utility and industrial applications. The assessment included visits to five turbine manufacturers. During these visits, in-depth discussions were held with design and manufacturing staff to obtain their views regarding the need for new sensors and controls for their advanced turbine designs. The Unsteady Combustion Facilities at the Morgantown Energy Technology Center was visited to assess the need for new sensors for gas turbine combustion research. Finally, a workshop was conducted at the South Carolina Energy Research and Development Center which provided a forum for industry, laboratory, and university engineers to discuss and prioritize sensor and control needs. The assessment identified more than 50 different measurement, control, and monitoring needs for advanced turbines that cannot currently be met from commercial sources. While all the identified needs are important, some are absolutely critical to the success of the ATS Program.

  8. A novel planar optical sensor for simultaneous monitoring of oxygen, carbon dioxide, pH and temperature.

    PubMed

    Borisov, Sergey M; Seifner, Roman; Klimant, Ingo

    2011-06-01

    The first quadruple luminescent sensor is presented which enables simultaneous detection of three chemical parameters and temperature. A multi-layer material is realized and combines two spectrally independent dually sensing systems. The first layer employs ethylcellulose containing the carbon dioxide sensing chemistry (fluorescent pH indicator 8-hydroxy-pyrene-1,3,6-trisulfonate (HPTS) and a lipophilic tetraalkylammonium base). The cross-linked polymeric beads stained with a phosphorescent iridium(III) complex are also dispersed in ethylcellulose and serve both for oxygen sensing and as a reference for HPTS. The second (pH/temperature) dually sensing system relies on the use of a pH-sensitive lipophilic seminaphthorhodafluor derivative and luminescent chromium(III)-activated yttrium aluminum borate particles (simultaneously acting as a temperature probe and as a reference for the pH indicator) which are embedded in polyurethane hydrogel layer. A silicone layer is used to spatially separate both dually sensing systems and to insure permeation selectivity for the CO(2)/O(2) layer. The CO(2)/O(2) and the pH/temperature layers are excitable with a blue and a red LED, respectively, and the emissions are isolated with help of optical filters. The measurements are performed at two modulation frequencies for each sensing system and the modified Dual Lifetime Referencing method is used to access the analytical information. The feasibility of the simultaneous four-parameter sensing is demonstrated. However, the practical applicability of the material may be compromised by its high complexity and by the performance of individual indicators. PMID:21221543

  9. Damage assessment of small-scale wind turbine blade using piezoelectric sensors

    NASA Astrophysics Data System (ADS)

    Rim, Mi-Sun; Kim, Sang-Woo; Kim, Eun-Ho; Lee, In

    2012-04-01

    Real-time structural health monitoring (SHM) systems are applied many fields. Recently, the interest about wind energy was increased by the demand of clean energy in the world and many researches were actively performed for applying SHM technology to wind turbine systems. Piezoelectric sensor is one kind of sensor which is widely used for SHM system to assess damage creation. In this paper, the small scale wind turbine blade was fabricated and health monitoring of the blade was performed using the piezoelectric sensor. The quasi-static bending test of the blade was carried out and the PVDF (Polyvinylidene fluoride) sensors, which are polymer type piezoelectric materials, were used for health monitoring. Two-cycle test was performed; the load was applied during 350 sec and removed at the first cycle, and load was applied again until the blade was broken completely at the second cycle. The voltage of PVDF sensors were measured during the quasi-static bending test in order to find out the moment when the damage occurrence started. The voltage of the sensor critically changed at the moment of damage occurred.

  10. Summary of the NASA Science Instrument, Observatories and Sensor Systems (SIOSS) Technology Assessment Roadmap

    NASA Technical Reports Server (NTRS)

    Stahl, H. Philip

    2011-01-01

    In August 2010, the NASA Office of Chief Technologist (OCT) commissioned an assessment of 15 different technology areas of importance to the future of NASA. Technology Assessment #8 (TA8) was Science Instruments, Observatories and Sensor Systems (SIOSS). SIOSS assessed the needs for optical technology ranging from detectors to lasers, x-ray mirrors to microwave antenna, in-situ spectrographs for on-surface planetary sample characterization to large space telescopes. This needs assessment looked across the entirety of NASA and not just the Science Mission Directorate. This paper summarizes the SIOSS findings and recommendations.

  11. Measurement of changes in blood oxygenation using Multispectral Optoacoustic Tomography (MSOT) allows assessment of tumor development

    NASA Astrophysics Data System (ADS)

    Tomaszewski, Michal R.; Quiros-Gonzalez, Isabel; Joseph, James; Bohndiek, Sarah E.

    2016-03-01

    The ability to evaluate tumor oxygenation in the clinic could indicate prognosis and enable treatment monitoring, since oxygen deficient cancer cells are more resistant to chemotherapy and radiotherapy. MultiSpectral Optoacoustic Tomography (MSOT) is a hybrid technique combining the high contrast of optical imaging with the spatial resolution and penetration depth similar to ultrasound. We aim to demonstrate that MSOT can be used to monitor the development of tumor vasculature. To establish the relationship between MSOT derived imaging biomarkers and biological changes during tumor development, we performed MSOT on nude mice (n=10) bearing subcutaneous xenograft U87 glioblastoma tumors using a small animal optoacoustic tomography system. The mice were maintained under inhalation anesthesia during imaging and respired oxygen content was modified between 21% and 100%. The measurements from early (week 4) and late (week 7) stages of tumor development were compared. To further explore the functionality of the blood vessels, we examined the evolution of changes in the abundance of oxy- and deoxyhemoglobin in the tumors in response to a gas challenge. We found that the kinetics of the change in oxygen saturation (SO2) were significantly different between small tumors and the healthy blood vessels in nearby normal tissue (p=0.0054). Furthermore, we showed that there was a significant difference in the kinetics of the gas challenge between small and large tumors (p=0.0015). We also found that the tumor SO2 was significantly correlated (p=0.0057) with the tumor necrotic fraction as assessed by H&E staining in histology. In the future, this approach may be of use in the clinic as a method for tumor staging and assessment of treatment response.

  12. Using Personal Sensors to Assess the Exposome and Acute Health Effects

    PubMed Central

    Nieuwenhuijsen, Mark J.; Donaire-Gonzalez, David; Foraster, Maria; Martinez, David; Cisneros, Andres

    2014-01-01

    Introduction: The exposome encompasses the totality of human environmental exposures. Recent developments in sensor technology have made it possible to better measure personal exposure to environmental pollutants and other factors. We aimed to discuss and demonstrate the recent developments in personal sensors to measure multiple exposures and possible acute health responses, and discuss the main challenges ahead. Methods: We searched for a range of sensors to measure air pollution, noise, temperature, UV, physical activity, location, blood pressure, heart rate and lung function and to obtain information on green space and emotional status/mood and put it on a person. Results and Conclusions: We discussed the recent developments and main challenges for personal sensors to measure multiple exposures. We found and put together a personal sensor set that measures a comprehensive set of personal exposures continuously over 24 h to assess part of the current exposome and acute health responses. We obtained data for a whole range of exposures and some acute health responses, but many challenges remain to apply the methodology for extended time periods and larger populations including improving the ease of wear, e.g., through miniaturization and extending battery life, and the reduction of costs. However, the technology is moving fast and opportunities will come closer for further wide spread use to assess, at least part of the exposome. PMID:25101766

  13. Oxygen indicators and intelligent inks for packaging food.

    PubMed

    Mills, Andrew

    2005-12-01

    The detection of oxygen using optical sensors is of increasing interest, especially in modified atmosphere food packaging (MAP), in which the package, usually containing food, is flushed with a gas, such as carbon dioxide or nitrogen. This tutorial review examines the ideal properties of an oxygen optical sensor for MAP and compares them with those developed to date, including the most recent advances. The basic technologies underpinning the different indicator types are described, examples given and their potential for application in MAP assessed. This tutorial review should be of interest to the MAP industry and researchers in optical sensors and oxygen sensing. PMID:16284666

  14. Dietary intake assessment using integrated sensors and software

    NASA Astrophysics Data System (ADS)

    Shang, Junqing; Pepin, Eric; Johnson, Eric; Hazel, David; Teredesai, Ankur; Kristal, Alan; Mamishev, Alexander

    2012-02-01

    The area of dietary assessment is becoming increasingly important as obesity rates soar, but valid measurement of the food intake in free-living persons is extraordinarily challenging. Traditional paper-based dietary assessment methods have limitations due to bias, user burden and cost, and therefore improved methods are needed to address important hypotheses related to diet and health. In this paper, we will describe the progress of our mobile Diet Data Recorder System (DDRS), where an electronic device is used for objective measurement on dietary intake in real time and at moderate cost. The DDRS consists of (1) a mobile device that integrates a smartphone and an integrated laser package, (2) software on the smartphone for data collection and laser control, (3) an algorithm to process acquired data for food volume estimation, which is the largest source of error in calculating dietary intake, and (4) database and interface for data storage and management. The estimated food volume, together with direct entries of food questionnaires and voice recordings, could provide dietitians and nutritional epidemiologists with more complete food description and more accurate food portion sizes. In this paper, we will describe the system design of DDRS and initial results of dietary assessment.

  15. Classification of frailty and falls history using a combination of sensor-based mobility assessments.

    PubMed

    Greene, Barry R; Doheny, Emer P; Kenny, Rose A; Caulfield, Brian

    2014-10-01

    Frailty is an important geriatric syndrome strongly linked to falls risk as well as increased mortality and morbidity. Taken alone, falls are the most common cause of injury and hospitalization and one of the principal causes of death and disability in older adults worldwide. Reliable determination of older adults' frailty state in concert with their falls risk could lead to targeted intervention and improved quality of care. We report a mobile assessment platform employing inertial and pressure sensors to quantify the balance and mobility of older adults using three physical assessments (timed up and go (TUG), five times sit to stand (FTSS) and quiet standing balance). This study examines the utility of each individual assessment, and the novel combination of assessments, to screen for frailty and falls risk in older adults.Data were acquired from inertial and pressure sensors during TUG, FTSS and balance assessments using a touchscreen mobile device, from 124 community dwelling older adults (mean age 75.9 ± 6.6 years, 91 female). Participants were given a comprehensive geriatric assessment which included questions on falls and frailty. Methods based on support vector machines (SVM) were developed using sensor-derived features from each physical assessment to classify patients at risk of falls risk and frailty.In classifying falls history, combining sensor data from the TUG, Balance and FTSS tests to a single classifier model per gender yielded mean cross-validated classification accuracy of 87.58% (95% CI: 84.47-91.03%) for the male model and 78.11% (95% CI: 75.38-81.10%) for the female model. These results compared well or exceeded those for classifier models for each test taken individually. Similarly, when classifying frailty status, combining sensor data from the TUG, balance and FTSS tests to a single classifier model per gender, yielded mean cross-validated classification accuracy of 93.94% (95% CI: 91.16-96.51%) for the male model and 84.14% (95% CI

  16. SSC Geopositional Assessment of the Advanced Wide Field Sensor

    NASA Technical Reports Server (NTRS)

    Ross, Kenton

    2007-01-01

    The objective is to provide independent verification of IRS geopositional accuracy claims and of the internal geopositional characterization provided by Lutes (2005). Six sub-scenes (quads) were assessed; Three from each AWiFS camera. Check points were manually matched to digital orthophoto quarter quadrangle (DOQQ) reference (assumed accuracy approx. 5 m, RMSE) Check points were selected to meet or exceed Federal Geographic Data Committee's guidelines. Used ESRI ArcGIS for data collection and SSC-written MATLAB scripts for data analysis.

  17. Non-aggregation based label free colorimetric sensor for the detection of Cu2+ based on catalyzing etching of gold nanorods by dissolve oxygen.

    PubMed

    Liu, Jia-Ming; Jiao, Li; Lin, Li-Ping; Cui, Ma-Lin; Wang, Xin-Xing; Zhang, Li-Hong; Zheng, Zhi-Yong; Jiang, Shu-Lian

    2013-12-15

    A label-free non-aggregation colorimetric sensor has been designed for the detection of Cu(2+), based on Cu(2+) catalyzing etching of gold nanorods (AuNRs) along longitudinal axis induced by dissolve oxygen in the presence of S2O3(2-), which caused the aspect ratio (length/width) of AuNRs to decrease and the color of the solution to distinctly change. The linear range and the detection limit (LD, calculated by 10 Sb/k, n=11) of this sensor were 0.080-4.8 µM Cu(2+) and 0.22 µM Cu(2+), respectively. This sensor has been utilized to detect Cu(2+) in tap water and human serum samples with the results agreeing well with those of inductively coupled plasma-mass spectroscopy (ICP-MS), showing its remarkable practicality. In order to prove the possibility of catalyzing AuNRs non-aggregation colorimetric sensor for the detection of Cu(2+), the morphological structures of AuNRs were characterized by high resolution transmission electron microscopy (HRTEM) and the sensing mechanism of colorimetric sensor for the detection of Cu(2+) was also discussed. PMID:24209363

  18. Effects of hydrogen sulfide on the heme coordination structure and catalytic activity of the globin-coupled oxygen sensor AfGcHK.

    PubMed

    Fojtikova, Veronika; Bartosova, Martina; Man, Petr; Stranava, Martin; Shimizu, Toru; Martinkova, Marketa

    2016-08-01

    AfGcHK is a globin-coupled histidine kinase that is one component of a two-component signal transduction system. The catalytic activity of this heme-based oxygen sensor is due to its C-terminal kinase domain and is strongly stimulated by the binding of O2 or CO to the heme Fe(II) complex in the N-terminal oxygen sensing domain. Hydrogen sulfide (H2S) is an important gaseous signaling molecule and can serve as a heme axial ligand, but its interactions with heme-based oxygen sensors have not been studied as extensively as those of O2, CO, and NO. To address this knowledge gap, we investigated the effects of H2S binding on the heme coordination structure and catalytic activity of wild-type AfGcHK and mutants in which residues at the putative O2-binding site (Tyr45) or the heme distal side (Leu68) were substituted. Adding Na2S to the initial OH-bound 6-coordinate Fe(III) low-spin complexes transformed them into SH-bound 6-coordinate Fe(III) low-spin complexes. The Leu68 mutants also formed a small proportion of verdoheme under these conditions. Conversely, when the heme-based oxygen sensor EcDOS was treated with Na2S, the initially formed Fe(III)-SH heme complex was quickly converted into Fe(II) and Fe(II)-O2 complexes. Interestingly, the autophosphorylation activity of the heme Fe(III)-SH complex was not significantly different from the maximal enzyme activity of AfGcHK (containing the heme Fe(III)-OH complex), whereas in the case of EcDOS the changes in coordination caused by Na2S treatment led to remarkable increases in catalytic activity. PMID:27395436

  19. 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.

  20. An assessment of gases in oxygen-deficient hay silos and the effects of forced ventilation.

    PubMed

    Kedan, G; Spielholz, P; Sjostrom, T; Trenary, B; Clark, R E

    2007-01-01

    Many modern tower silos used in the agricultural industry for hay and grain storage are oxygen-limiting by design. Forced-air ventilation using a forage blower is a method commonly used to decrease concentrations of toxic and asphyxiant gases and to increase the O2 content within a silo headspace prior to worker entry. This article describes the methods used to measure gas concentrations and the results obtained from a pilot study by the Washington Fatality Assessment and Control Evaluation (FACE) program of two oxygen-limiting forage tower silos in eastern Washington State. The silos were monitored for oxygen (O2), nitrogen dioxide (NO2), and carbon dioxide (CO2). Measured O2 concentrations were low in all areas of the headspaces monitored for both silos. After beginning forced-air ventilation, O2 concentrations within the silo headspace returned to ambient levels within 8 to 20 min. Nitrogen dioxide levels exceeded the Washington Industrial Safety and Health Act (WISHA) short-term exposure limit (STEL) in the silo that was filled six days earlier (silo 2), but not in the silo that was filled four days earlier (silo 1). The NO2 concentration in silo 2 decreased to below the WISHA STEL within 15 min of starting ventilation but began to rise shortly after ventilation was stopped. Carbon dioxide, which was only measured in silo 1, was detected at 2% within the headspace of this silo. The carbon dioxide concentration decreased to <1% within 3 min of starting ventilation. PMID:17370916

  1. Using broadband spatially resolved NIRS to assess muscle oxygenation during altered running protocols

    NASA Astrophysics Data System (ADS)

    Koukourakis, Georg; Vafiadou, Maria; Steimers, André; Geraskin, Dmitri; Neary, Patrick; Kohl-Bareis, Matthias

    2009-07-01

    We used spatially resolved near-infrared spectroscopy (SRS-NIRS) to assess calf and thigh muscle oxygenation during running on a motor-driven treadmill. Two protocols were used: An incremental speed protocol (velocity = 6 - 12 km/h, ▵v = 2 km/h) was performed in 3 minute stages, while a pacing paradigm modulated step frequency alternatively (2.3 Hz [SLow]; 3.3 Hz [SHigh]) during a constant velocity for 2 minutes each. A SRS-NIRS broadband system (600 - 1000 nm) was used to measure total haemoglobin concentration and oxygen saturation (SO2). An accelerometer was placed on the hip joints to measure limb acceleration through the experiment. The data showed that the calf (SO2 58 to 42%) desaturated to a significantly lower level than the thigh (61 to 54%). During the pacing protocol, SO2 was significantly different between the SLow vs. SHigh trials. Additionally, physiological data as measured by spirometry were different between the SLow vs. SHigh pacing trials (VO2 (2563+/- 586 vs. 2503 +/- 605 mL/min). Significant differences in VO2 at the same workload (speed) indicate alterations in mechanical efficiency. These data suggest that SRS broadband NIRS can be used to discern small changes in muscle oxygenation, making this device useful for metabolic exercise studies in addition to spirometry and movement monitoring by accelerometers.

  2. Health assessment of gasoline and fuel oxygenate vapors: generation and characterization of test materials.

    PubMed

    Henley, Michael; Letinski, Daniel J; Carr, John; Caro, Mario L; Daughtrey, Wayne; White, Russell

    2014-11-01

    In compliance with the Clean Air Act regulations for fuel and fuel additive registration, the petroleum industry, additive manufacturers, and oxygenate manufacturers have conducted comparative toxicology testing on evaporative emissions of gasoline alone and gasoline containing fuel oxygenates. To mimic real world exposures, a generation method was developed that produced test material similar in composition to the re-fueling vapor from an automotive fuel tank at near maximum in-use temperatures. Gasoline vapor was generated by a single-step distillation from a 1000-gallon glass-lined kettle wherein approximately 15-23% of the starting material was slowly vaporized, separated, condensed and recovered as test article. This fraction was termed vapor condensate (VC) and was prepared for each of the seven test materials, namely: baseline gasoline alone (BGVC), or gasoline plus an ether (G/MTBE, G/ETBE, G/TAME, or G/DIPE), or gasoline plus an alcohol (G/EtOH or G/TBA). The VC test articles were used for the inhalation toxicology studies described in the accompanying series of papers in this journal. These studies included evaluations of subchronic toxicity, neurotoxicity, immunotoxicity, genotoxicity, reproductive and developmental toxicity. Results of these studies will be used for comparative risk assessments of gasoline and gasoline/oxygenate blends by the US Environmental Protection Agency. PMID:24852493

  3. Development of a colorimetric sensor array for squid spoilage assessment.

    PubMed

    Zaragozá, Patricia; Fuentes, Ana; Ruiz-Rico, María; Vivancos, José-Luis; Fernández-Segovia, Isabel; Ros-Lis, José V; Barat, José M; Martínez-Máñez, Ramón

    2015-05-15

    The aim of this work was to develop and evaluate a rapid, easy-to-use optoelectronic system for the shelf-life assessment of squid in cold storage. For this purpose, an optoelectronic nose was designed, which consisted of an array containing six sensing materials prepared by combining different dyes and two inorganic supports (aluminium oxide and silica gel). Samples were packaged with the colorimetric array and kept in cold storage for 12 days. Squid spoilage was monitored simultaneously by the colorimetric array and by the physico-chemical and microbial analyses during storage. Samples exceeded the acceptability limits for microbial counts on the third day. PCA analysis carried out with CIELab showed that the colorimetric array was able to discriminate between fresh squid fit for consumption and spoiled squid. The statistical models obtained by PLS, with the optoelectronic nose, successfully predicted CO2 and O2 content in the headspace as well as microbial growth. PMID:25577086

  4. Frequency variation and sensor contribution assessment: Application to an offshore platform in the South China Sea

    NASA Astrophysics Data System (ADS)

    Liu, Fushun; Li, Huajun; Wang, Weiying; Li, Wei; Wang, Bin

    2015-02-01

    In this paper, a time-frequency and multiple-sensor assessment method is presented and then applied to an offshore platform in the South China Sea with the goal of providing a more suitable time duration of measured signals and evaluating each sensor's contribution to mode shapes of interest. By processing all measured signals simultaneously, a series of linear parameters are used to fit the measured signals. A moving window in overlapping steps along the time record of a non-stationary signal is used for time-frequency analysis while a series of amplitude matrices are obtained for all sliced segments. These segments are then used to evaluate each sensor's contribution to some mode(s) of interest. Compared with the short-time Fourier transform (STFT) or S-transform method, the frequencies used in this time-frequency analysis are shared by the sensors involved so that the variations in the results due to the characteristics of different sensors are avoided. In addition, the approach requires only a short-duration segment to obtain high-frequency resolution, which will improve the computing efficiency of modal analysis using measured seat est data. The proposed method could also be used to estimate damping ratios and each sensor's contribution to modes of interest based on the analysis of the series of amplitude matrices; this could be used to guide the installation of sensors in field tests of offshore structures. To demonstrate the proposed method with a time-frequency analysis, a numerical example of a synthesized signal with five segments, each with its owns different frequency componentsincluding a relatively weaker component, is constructed; numerical results from the analysis of this example signal indicate that the approach could yield a sharper image with a good computing efficiency. The second example simulates three signals that represent multiple measurements; this example is used to study each sensor

  5. Using Optical Oxygen Sensors and Injection Experiments to Determine in situ Microbial Rate Constants for Methane Oxidation and Heterotrophic Respiration in a Boreal Bog and Fen

    NASA Astrophysics Data System (ADS)

    Waldo, N.; Moorberg, C.; Waldrop, M. P.; Turetsky, M. R.; Neumann, R. B.

    2015-12-01

    Wetlands are the largest natural source of methane to the atmosphere, and play a key role in feedback cycles to climate change. In recognition of this, many researchers are developing process-based models of wetland methane emissions at various scales. In these models, the three key biogeochemical reactions are methane production, methane oxidation, and heterotrophic respiration, and they are modeled using Michaelis-Menten kinetics. The majority of Michaelis-Menten rate constants used in models are based on experiments involving slurries of peat incubated in vials. While these slurries provide a highly controlled setting, they are different from in situ conditions in multiple ways; notably they lack live plants and the centimeter-scale heterogeneities that exist in the field. To determine rate constants in a system more representative of in situ conditions, we extracted peat cores intact from a bog and fen located in the Bonanza Creek Experimental Forest near Fairbanks, Alaska and part of the Alaska Peatland Experiment (APEX) research program. Into those cores we injected water with varying concentrations of methane and oxygen at multiple depths. We used planar oxygen sensors installed on the peat cores to collect high resolution, two dimensional oxygen concentration data during the injections and used oxygen consumption rates under various conditions to calculate rate constants. Results were compared to a similar but smaller set of injection experiments conducted against planar oxygen sensors installed in the bog. Results will inform parametrization of microbial processes in wetland models, improving estimates of methane emissions both under current climate conditions and in the future.

  6. Dissolved Oxygen Sensor in Animal-Borne Instruments: An Innovation for Monitoring the Health of Oceans and Investigating the Functioning of Marine Ecosystems.

    PubMed

    Bailleul, Frederic; Vacquie-Garcia, Jade; Guinet, Christophe

    2015-01-01

    The current decline in dissolved oxygen concentration within the oceans is a sensitive indicator of the effect of climate change on marine environment. However the impact of its declining on marine life and ecosystems' health is still quite unclear because of the difficulty in obtaining in situ data, especially in remote areas, like the Southern Ocean (SO). Southern elephant seals (Mirounga leonina) proved to be a relevant alternative to the traditional oceanographic platforms to measure physical and biogeochemical structure of oceanic regions rarely observed. In this study, we use a new stage of development in biologging technology to draw a picture of dissolved oxygen concentration in the SO. We present the first results obtained from a dissolved oxygen sensor added to Argos CTD-SRDL tags and deployed on 5 female elephant seals at Kerguelen. From October 2010 and October 2011, 742 oxygen profiles associated with temperature and salinity measurements were recorded. Whether a part of the data must be considered cautiously, especially because of offsets and temporal drifts of the sensors, the range of values recorded was consistent with a concomitant survey conducted from a research vessel (Keops-2 project). Once again, elephant seals reinforced the relationship between marine ecology and oceanography, delivering essential information about the water masses properties and the biological status of the Southern Ocean. But more than the presentation of a new stage of development in animal-borne instrumentation, this pilot study opens a new field of investigation in marine ecology and could be enlarged in a near future to other key marine predators, especially large fish species like swordfish, tuna or sharks, for which dissolved oxygen is expected to play a crucial role in distribution and behaviour. PMID:26200780

  7. Dissolved Oxygen Sensor in Animal-Borne Instruments: An Innovation for Monitoring the Health of Oceans and Investigating the Functioning of Marine Ecosystems

    PubMed Central

    Bailleul, Frederic; Vacquie-Garcia, Jade; Guinet, Christophe

    2015-01-01

    The current decline in dissolved oxygen concentration within the oceans is a sensitive indicator of the effect of climate change on marine environment. However the impact of its declining on marine life and ecosystems’ health is still quite unclear because of the difficulty in obtaining in situ data, especially in remote areas, like the Southern Ocean (SO). Southern elephant seals (Mirounga leonina) proved to be a relevant alternative to the traditional oceanographic platforms to measure physical and biogeochemical structure of oceanic regions rarely observed. In this study, we use a new stage of development in biologging technology to draw a picture of dissolved oxygen concentration in the SO. We present the first results obtained from a dissolved oxygen sensor added to Argos CTD-SRDL tags and deployed on 5 female elephant seals at Kerguelen. From October 2010 and October 2011, 742 oxygen profiles associated with temperature and salinity measurements were recorded. Whether a part of the data must be considered cautiously, especially because of offsets and temporal drifts of the sensors, the range of values recorded was consistent with a concomitant survey conducted from a research vessel (Keops-2 project). Once again, elephant seals reinforced the relationship between marine ecology and oceanography, delivering essential information about the water masses properties and the biological status of the Southern Ocean. But more than the presentation of a new stage of development in animal-borne instrumentation, this pilot study opens a new field of investigation in marine ecology and could be enlarged in a near future to other key marine predators, especially large fish species like swordfish, tuna or sharks, for which dissolved oxygen is expected to play a crucial role in distribution and behaviour. PMID:26200780

  8. Assessing UAV platform types and optical sensor specifications

    NASA Astrophysics Data System (ADS)

    Altena, B.; Goedemé, T.

    2014-05-01

    Photogrammetric acquisition with unmanned aerial vehicles (UAV) has grown extensively over the last couple of years. Such mobile platforms and their processing software have matured, resulting in a market which offers off-the-shelf mapping solutions to surveying companies and geospatial enterprises. Different approaches in platform type and optical instruments exist, though its resulting products have similar specifications. To demonstrate differences in acquisitioning practice, a case study over an open mine was flown with two different off-the-shelf UAVs (a fixed-wing and a multi-rotor). The resulting imagery is analyzed to clarify the differences in collection quality. We look at image settings, and stress the fact of photographic experience if manual setting are applied. For mapping production it might be safest to set the camera on automatic. Furthermore, we try to estimate if blur is present due to image motion. A subtle trend seems to be present, for the fast flying platform though its extent is of similar order to the slow moving one. It shows both systems operate at their limits. Finally, the lens distortion is assessed with special attention to chromatic aberration. Here we see that through calibration such aberrations could be present, however detecting this phenomena directly on imagery is not straightforward. For such effects a normal lens is sufficient, though a better lens and collimator does give significant improvement.

  9. A Compressed Sensing-Based Wearable Sensor Network for Quantitative Assessment of Stroke Patients.

    PubMed

    Yu, Lei; Xiong, Daxi; Guo, Liquan; Wang, Jiping

    2016-01-01

    Clinical rehabilitation assessment is an important part of the therapy process because it is the premise for prescribing suitable rehabilitation interventions. However, the commonly used assessment scales have the following two drawbacks: (1) they are susceptible to subjective factors; (2) they only have several rating levels and are influenced by a ceiling effect, making it impossible to exactly detect any further improvement in the movement. Meanwhile, energy constraints are a primary design consideration in wearable sensor network systems since they are often battery-operated. Traditionally, for wearable sensor network systems that follow the Shannon/Nyquist sampling theorem, there are many data that need to be sampled and transmitted. This paper proposes a novel wearable sensor network system to monitor and quantitatively assess the upper limb motion function, based on compressed sensing technology. With the sparse representation model, less data is transmitted to the computer than with traditional systems. The experimental results show that the accelerometer signals of Bobath handshake and shoulder touch exercises can be compressed, and the length of the compressed signal is less than 1/3 of the raw signal length. More importantly, the reconstruction errors have no influence on the predictive accuracy of the Brunnstrom stage classification model. It also indicated that the proposed system can not only reduce the amount of data during the sampling and transmission processes, but also, the reconstructed accelerometer signals can be used for quantitative assessment without any loss of useful information. PMID:26861337

  10. A Compressed Sensing-Based Wearable Sensor Network for Quantitative Assessment of Stroke Patients

    PubMed Central

    Yu, Lei; Xiong, Daxi; Guo, Liquan; Wang, Jiping

    2016-01-01

    Clinical rehabilitation assessment is an important part of the therapy process because it is the premise for prescribing suitable rehabilitation interventions. However, the commonly used assessment scales have the following two drawbacks: (1) they are susceptible to subjective factors; (2) they only have several rating levels and are influenced by a ceiling effect, making it impossible to exactly detect any further improvement in the movement. Meanwhile, energy constraints are a primary design consideration in wearable sensor network systems since they are often battery-operated. Traditionally, for wearable sensor network systems that follow the Shannon/Nyquist sampling theorem, there are many data that need to be sampled and transmitted. This paper proposes a novel wearable sensor network system to monitor and quantitatively assess the upper limb motion function, based on compressed sensing technology. With the sparse representation model, less data is transmitted to the computer than with traditional systems. The experimental results show that the accelerometer signals of Bobath handshake and shoulder touch exercises can be compressed, and the length of the compressed signal is less than 1/3 of the raw signal length. More importantly, the reconstruction errors have no influence on the predictive accuracy of the Brunnstrom stage classification model. It also indicated that the proposed system can not only reduce the amount of data during the sampling and transmission processes, but also, the reconstructed accelerometer signals can be used for quantitative assessment without any loss of useful information. PMID:26861337

  11. Advanced Sensors and Controls for Building Applications: Market Assessment and Potential R&D Pathways

    SciTech Connect

    Brambley, Michael R.; Haves, Philip; McDonald, Sean C.; Torcellini, Paul; Hansen, David G.; Holmberg, David; Roth, Kurt

    2005-04-13

    Significant energy savings can be achieved in commercial building operation, along with increased comfort and control for occupants, through the implementation of advanced technologies. This document provides a market assessment of existing building sensors and controls and presents a range of technology pathways (R&D options) for pursuing advanced sensors and building control strategies. This paper is actually a synthesis of five other white papers: the first describes the market assessment including estimates of market potential and energy savings for sensors and control strategies currently on the market as well as a discussion of market barriers to these technologies. The other four cover technology pathways: (1) current applications and strategies for new applications, (2) sensors and controls, (3) networking, security, and protocols and standards, and (4) automated diagnostics, performance monitoring, commissioning, optimal control and tools. Each technology pathway chapter gives an overview of the technology or application. This is followed by a discussion of needs and the current status of the technology. Finally, a series of research topics is proposed.

  12. Human Body Parts Tracking and Kinematic Features Assessment Based on RSSI and Inertial Sensor Measurements

    PubMed Central

    Blumrosen, Gaddi; Luttwak, Ami

    2013-01-01

    Acquisition of patient kinematics in different environments plays an important role in the detection of risk situations such as fall detection in elderly patients, in rehabilitation of patients with injuries, and in the design of treatment plans for patients with neurological diseases. Received Signal Strength Indicator (RSSI) measurements in a Body Area Network (BAN), capture the signal power on a radio link. The main aim of this paper is to demonstrate the potential of utilizing RSSI measurements in assessment of human kinematic features, and to give methods to determine these features. RSSI measurements can be used for tracking different body parts' displacements on scales of a few centimeters, for classifying motion and gait patterns instead of inertial sensors, and to serve as an additional reference to other sensors, in particular inertial sensors. Criteria and analytical methods for body part tracking, kinematic motion feature extraction, and a Kalman filter model for aggregation of RSSI and inertial sensor were derived. The methods were verified by a set of experiments performed in an indoor environment. In the future, the use of RSSI measurements can help in continuous assessment of various kinematic features of patients during their daily life activities and enhance medical diagnosis accuracy with lower costs. PMID:23979481

  13. Assessing the sources and magnitude of diurnal nitrate variability in the San Joaquin River (California) with an in situ optical nitrate sensor and dual nitrate isotopes

    USGS Publications Warehouse

    Pellerin, B.A.; Downing, B.D.; Kendall, C.; Dahlgren, R.A.; Kraus, T.E.C.; Saraceno, J.; Spencer, R.G.M.; Bergamaschi, B.A.

    2009-01-01

    1. We investigated diurnal nitrate (NO3-) concentration variability in the San Joaquin River using an in situ optical NO3- sensor and discrete sampling during a 5-day summer period characterized by high algal productivity. Dual NO3- isotopes (??15NNO3 and ??18O NO3) and dissolved oxygen isotopes (??18O DO) were measured over 2 days to assess NO3- sources and biogeochemical controls over diurnal time-scales. 2. Concerted temporal patterns of dissolved oxygen (DO) concentrations and ??18ODO were consistent with photosynthesis, respiration and atmospheric O2 exchange, providing evidence of diurnal biological processes independent of river discharge. 3. Surface water NO3- concentrations varied by up to 22% over a single diurnal cycle and up to 31% over the 5-day study, but did not reveal concerted diurnal patterns at a frequency comparable to DO concentrations. The decoupling of ??15NNO3 and ??18ONO3 isotopes suggests that algal assimilation and denitrification are not major processes controlling diurnal NO3- variability in the San Joaquin River during the study. The lack of a clear explanation for NO 3- variability likely reflects a combination of riverine biological processes and time-varying physical transport of NO3- from upstream agricultural drains to the mainstem San Joaquin River. 4. The application of an in situ optical NO3- sensor along with discrete samples provides a view into the fine temporal structure of hydrochemical data and may allow for greater accuracy in pollution assessment. ?? 2008 Blackwell Publishing Ltd.

  14. Next-Generation Psychiatric Assessment: Using Smartphone Sensors to Monitor Behavior and Mental Health

    PubMed Central

    Ben-Zeev, Dror; Scherer, Emily A.; Wang, Rui; Xie, Haiyi; Campbell, Andrew T.

    2015-01-01

    Objective Optimal mental health care is dependent upon sensitive and early detection of mental health problems. The current study introduces a state-of-the-art method for remote behavioral monitoring that transports assessment out of the clinic and into the environments in which individuals negotiate their daily lives. The objective of this study was examine whether the information captured with multi-modal smartphone sensors can serve as behavioral markers for one’s mental health. We hypothesized that: a) unobtrusively collected smartphone sensor data would be associated with individuals’ daily levels of stress, and b) sensor data would be associated with changes in depression, stress, and subjective loneliness over time. Methods A total of 47 young adults (age range: 19–30 y.o.) were recruited for the study. Individuals were enrolled as a single cohort and participated in the study over a 10-week period. Participants were provided with smartphones embedded with a range of sensors and software that enabled continuous tracking of their geospatial activity (using GPS and WiFi), kinesthetic activity (using multi-axial accelerometers), sleep duration (modeled using device use data, accelerometer inferences, ambient sound features, and ambient light levels), and time spent proximal to human speech (i.e., speech duration using microphone and speech detection algorithms). Participants completed daily ratings of stress, as well as pre/post measures of depression (Patient Health Questionnaire-9), stress (Perceived Stress Scale), and loneliness (Revised UCLA Loneliness Scale). Results Mixed-effects linear modeling showed that sensor-derived geospatial activity (p<.05), sleep duration (p<.05), and variability in geospatial activity (p<.05), were associated with daily stress levels. Penalized functional regression showed associations between changes in depression and sensor-derived speech duration (p<.05), geospatial activity (p<.05), and sleep duration (p<.05). Changes

  15. Novel approach to ambulatory assessment of human segmental orientation on a wearable sensor system.

    PubMed

    Liu, Kun; Liu, Tao; Shibata, Kyoko; Inoue, Yoshio; Zheng, Rencheng

    2009-12-11

    A new method using a double-sensor difference based algorithm for analyzing human segment rotational angles in two directions for segmental orientation analysis in the three-dimensional (3D) space was presented. A wearable sensor system based only on triaxial accelerometers was developed to obtain the pitch and yaw angles of thigh segment with an accelerometer approximating translational acceleration of the hip joint and two accelerometers measuring the actual accelerations on the thigh. To evaluate the method, the system was first tested on a 2 degrees of freedom mechanical arm assembled out of rigid segments and encoders. Then, to estimate the human segmental orientation, the wearable sensor system was tested on the thighs of eight volunteer subjects, who walked in a straight forward line in the work space of an optical motion analysis system at three self-selected speeds: slow, normal and fast. In the experiment, the subject was assumed to walk in a straight forward way with very little trunk sway, skin artifacts and no significant internal/external rotation of the leg. The root mean square (RMS) errors of the thigh segment orientation measurement were between 2.4 degrees and 4.9 degrees during normal gait that had a 45 degrees flexion/extension range of motion. Measurement error was observed to increase with increasing walking speed probably because of the result of increased trunk sway, axial rotation and skin artifacts. The results show that, without integration and switching between different sensors, using only one kind of sensor, the wearable sensor system is suitable for ambulatory analysis of normal gait orientation of thigh and shank in two directions of the segment-fixed local coordinate system in 3D space. It can then be applied to assess spatio-temporal gait parameters and monitoring the gait function of patients in clinical settings. PMID:19748624

  16. Assessing Sensor Accuracy for Non-Adjunct Use of Continuous Glucose Monitoring

    PubMed Central

    Patek, Stephen D.; Ortiz, Edward Andrew; Breton, Marc D.

    2015-01-01

    Abstract Background: The level of continuous glucose monitoring (CGM) accuracy needed for insulin dosing using sensor values (i.e., the level of accuracy permitting non-adjunct CGM use) is a topic of ongoing debate. Assessment of this level in clinical experiments is virtually impossible because the magnitude of CGM errors cannot be manipulated and related prospectively to clinical outcomes. Materials and Methods: A combination of archival data (parallel CGM, insulin pump, self-monitoring of blood glucose [SMBG] records, and meals for 56 pump users with type 1 diabetes) and in silico experiments was used to “replay” real-life treatment scenarios and relate sensor error to glycemic outcomes. Nominal blood glucose (BG) traces were extracted using a mathematical model, yielding 2,082 BG segments each initiated by insulin bolus and confirmed by SMBG. These segments were replayed at seven sensor accuracy levels (mean absolute relative differences [MARDs] of 3–22%) testing six scenarios: insulin dosing using sensor values, threshold, and predictive alarms, each without or with considering CGM trend arrows. Results: In all six scenarios, the occurrence of hypoglycemia (frequency of BG levels ≤50 mg/dL and BG levels ≤39 mg/dL) increased with sensor error, displaying an abrupt slope change at MARD =10%. Similarly, hyperglycemia (frequency of BG levels ≥250 mg/dL and BG levels ≥400 mg/dL) increased and displayed an abrupt slope change at MARD=10%. When added to insulin dosing decisions, information from CGM trend arrows, threshold, and predictive alarms resulted in improvement in average glycemia by 1.86, 8.17, and 8.88 mg/dL, respectively. Conclusions: Using CGM for insulin dosing decisions is feasible below a certain level of sensor error, estimated in silico at MARD=10%. In our experiments, further accuracy improvement did not contribute substantively to better glycemic outcomes. PMID:25436913

  17. A full reference image quality assessment method for retina-like sensor

    NASA Astrophysics Data System (ADS)

    Luo, Zhihu; Cao, Fengmei

    2013-12-01

    Retina_like sensor is characterized by a space-variant resolution mimicking the distribution of photoreceptors in the human retina. It is devided into two areas-the central area and the peripheral area. Density of pixels is highest in the center and decreases monotonically toward the periphery area. Such space-varant image allows high-resolution tasks using the central region while maintaining a lower resolution part providing relevant information about the background. In high speed forward motion field, because the image system is approaching or leaving the object in a high speed, the recorded image will be blurred radially. However, this kind of radial blur can be reduced by changing the pixel layout of retina_like sensor. So image quality assessment studies carried out on the different structures of the retina_like sensor output image can provide theoretical guidance for the establishment of the optimal layout of the retina_like sensor. This paper first analyzes the distortion process of the retina_like sensor output image in high-speed forward motion and find that such a distortion of the image including under-sampled distortion and radial blur distortion. Based on the characteristics of the distorted image, the author puts forward a full reference image quality assessment method, named Qretina, for such images. The method is according to the distortion process. Do under-sampling evaluation and radial fuzzy evaluation firstly, then weigh the two parts to get the final image quality evaluation results. The experimental results show that Qretina has better performance than the SSIM.

  18. Health assessment of gasoline and fuel oxygenate vapors: Reproductive toxicity assessment

    PubMed Central

    Gray, Thomas M.; Steup, David; Roberts, Linda G.; O'Callaghan, James P.; Hoffman, Gary; Schreiner, Ceinwen A.; Clark, Charles R.

    2016-01-01

    Vapor condensates of baseline gasoline (BGVC), or gasoline-blended with methyl tertiary butyl ether (G/MTBE), ethyl t-butyl ether (G/ETBE), t-amyl methyl ether (G/TAME), diisopropyl ether (G/DIPE), ethanol (G/EtOH), or t-butyl alcohol (G/TBA) were evaluated for reproductive toxicity in rats at target concentrations of 2000, 10,000, or 20,000 mg/m3, 6 h/day, 7 days/week. BGVC and G/MTBE were assessed over two generations, the others for one generation. BGVC and G/MTBE F1 offspring were evaluated for neuropathology and changes in regional brain glial fibrillary acidic protein content. No neurotoxicity was observed. Male kidney weight was increased consistent with light hydrocarbon nephropathy. In adult rats, decreased body weight gain and increased liver weight were seen. Spleen weight decreased in adults and pups exposed to G/TBA. No pathological changes to reproductive organs occurred in any study. Decreased food consumption was seen in G/TAME lactating females. Transient decreases in G/TAME off-spring weights were observed during lactation. Except for a minor increase in time to mating in G/TBA which did not affect other reproductive parameters, there were no adverse reproductive findings. The NOAEL for reproductive and offspring parameters was 20,000 mg/m3 for all vapor condensates except for lower offspring NOAELs of 10,000 mg/m3 for G/TBA and 2000 mg/m3 for G/TAME. PMID:24813181

  19. Health assessment of gasoline and fuel oxygenate vapors: reproductive toxicity assessment.

    PubMed

    Gray, Thomas M; Steup, David; Roberts, Linda G; O'Callaghan, James P; Hoffman, Gary; Schreiner, Ceinwen A; Clark, Charles R

    2014-11-01

    Vapor condensates of baseline gasoline (BGVC), or gasoline-blended with methyl tertiary butyl ether (G/MTBE), ethyl t-butyl ether (G/ETBE), t-amyl methyl ether (G/TAME), diisopropyl ether (G/DIPE), ethanol (G/EtOH), or t-butyl alcohol (G/TBA) were evaluated for reproductive toxicity in rats at target concentrations of 2000, 10,000, or 20,000mg/m(3), 6h/day, 7days/week. BGVC and G/MTBE were assessed over two generations, the others for one generation. BGVC and G/MTBE F1 offspring were evaluated for neuropathology and changes in regional brain glial fibrillary acidic protein content. No neurotoxicity was observed. Male kidney weight was increased consistent with light hydrocarbon nephropathy. In adult rats, decreased body weight gain and increased liver weight were seen. Spleen weight decreased in adults and pups exposed to G/TBA. No pathological changes to reproductive organs occurred in any study. Decreased food consumption was seen in G/TAME lactating females. Transient decreases in G/TAME offspring weights were observed during lactation. Except for a minor increase in time to mating in G/TBA which did not affect other reproductive parameters, there were no adverse reproductive findings. The NOAEL for reproductive and offspring parameters was 20,000mg/m(3) for all vapor condensates except for lower offspring NOAELs of 10,000mg/m(3) for G/TBA and 2000mg/m(3) for G/TAME. PMID:24813181

  20. Health assessment of gasoline and fuel oxygenate vapors: subchronic inhalation toxicity.

    PubMed

    Clark, Charles R; Schreiner, Ceinwen A; Parker, Craig M; Gray, Thomas M; Hoffman, Gary M

    2014-11-01

    Sprague Dawley rats were exposed via inhalation to vapor condensates of either gasoline or gasoline combined with various fuel oxygenates to assess whether their use in gasoline influences the hazard of evaporative emissions. Test substances included vapor condensates prepared from an EPA described "baseline gasoline" (BGVC), or gasoline combined with methyl tertiary butyl ether (G/MTBE), ethyl t-butyl ether (G/ETBE), t-amyl methyl ether (G/TAME), diisopropyl ether (G/DIPE), ethanol (G/EtOH), or t-butyl alcohol (G/TBA). Target concentrations were 0, 2000, 10,000 or 20,000mg/m(3) and exposures were for 6h/day, 5days/week for 13weeks. A portion of the animals were maintained for a four week recovery period to determine the reversibility of potential adverse effects. Increased kidney weight and light hydrocarbon nephropathy (LHN) were observed in treated male rats in all studies which were reversible or nearly reversible after 4weeks recovery. LHN is unique to male rats and is not relevant to human toxicity. The no observed effect level (NOAEL) in all studies was 10,000mg/m(3), except for G/MTBE (<2000) and G/TBA (2000). The results provide evidence that use of the studied oxygenates are unlikely to increase the hazard of evaporative emissions during refueling, compared to those from gasoline alone. PMID:25020274

  1. A Trajectory-Based Coverage Assessment Approach for Universal Sensor Networks.

    PubMed

    Qin, Ningning; Zheng, Xin; Tian, Guiyun

    2015-01-01

    To solve the problem of coverage performance assessment, this study proposes an evaluation method based on the trajectory of the target, which is applicable to universal sensor networks, including both heterogeneous and homogeneous sensor networks. Different from the traditional Voronoi algorithm, the proposed Improved Coverage Force Division (ICFD) plans a coverage force division map whichscales the qualitative coverage performancebasedon both covering intensities andlocations of the nodes. Furthermore, the Trajectory-based Evaluating Schedule (TES) is responsible for solving the quantitative coverage evaluationproblem by measuringthe resulting trajectories' Balance Values (BVs). A model of weak-point ranking conjoined in consideration of coverage force and distance can guide future deployment to compensate coverage. Comparative trials using the greedy algorithm, Voronoi algorithm, and the proposed TES verify that TES achieves the approximate results for two-stage and multistage heterogeneous sensor networks with acceptable difference and lower complexity, and it is superior to the Voronoi algorithm in homogeneous sensor networks interms of breaking the four-point circle block. PMID:26270667

  2. Wireless sensor networks for planetary exploration: Experimental assessment of communication and deployment

    NASA Astrophysics Data System (ADS)

    Sanz, D.; Barrientos, A.; Garzón, M.; Rossi, C.; Mura, M.; Puccinelli, D.; Puiatti, A.; Graziano, M.; Medina, A.; Mollinedo, L.; de Negueruela, C.

    2013-09-01

    Planetary surface exploration is an appealing application of wireless sensor networks that has been investigated in recent years by the space community, including the European Space Agency. The idea is to deploy a number of self-organizing sensor nodes forming a wireless networked architecture to provide a distributed instrument for the study and exploration of a planetary body. To explore this concept, ESA has funded the research project RF Wireless for Planetary Exploration (RF-WIPE), carried out by GMV, SUPSI and UPM. The purpose of RF-WIPE was to simulate and prototype a wireless sensor network in order to assess the potential and limitations of the technology for the purposes of planetary exploration. In this paper, we illustrate the results of the work carried out within the context of RF-WIPE. Two test case scenarios have been investigated: a distributed sensor network-based instrument and networked planetary surface exploration. Each scenario is related to a particular network configuration. For such configurations, energy models and communication protocols have been developed, simulated, and validated both on laboratory tests and with outdoor field tests. Additionally, node deployment was investigated, and a deployment system based on a mobile robotics platform has been designed and tested.

  3. Are We There Yet? Feasibility of Continuous Stress Assessment via Wireless Physiological Sensors

    PubMed Central

    Rahman, Mahbubur; Bari, Rummana; Ali, Amin Ahsan; Sharmin, Moushumi; Raij, Andrew; Hovsepian, Karen; Hossain, Syed Monowar; Ertin, Emre; Kennedy, Ashley; Epstein, David H.; Preston, Kenzie L.; Jobes, Michelle; Beck, J. Gayle; Kedia, Satish; Ward, Kenneth D.; al'Absi, Mustafa; Kumar, Santosh

    2015-01-01

    Stress can lead to headaches and fatigue, precipitate addictive behaviors (e.g., smoking, alcohol and drug use), and lead to cardiovascular diseases and cancer. Continuous assessment of stress from sensors can be used for timely delivery of a variety of interventions to reduce or avoid stress. We investigate the feasibility of continuous stress measurement via two field studies using wireless physiological sensors — a four-week study with illicit drug users (n = 40), and a one-week study with daily smokers and social drinkers (n = 30). We find that 11+ hours/day of usable data can be obtained in a 4-week study. Significant learning effect is observed after the first week and data yield is seen to be increasing over time even in the fourth week. We propose a framework to analyze sensor data yield and find that losses in wireless channel is negligible; the main hurdle in further improving data yield is the attachment constraint. We show the feasibility of measuring stress minutes preceding events of interest and observe the sensor-derived stress to be rising prior to self-reported stress and smoking events. PMID:25821861

  4. Automated Health Alerts Using In-Home Sensor Data for Embedded Health Assessment

    PubMed Central

    Guevara, Rainer Dane; Rantz, Marilyn

    2015-01-01

    We present an example of unobtrusive, continuous monitoring in the home for the purpose of assessing early health changes. Sensors embedded in the environment capture behavior and activity patterns. Changes in patterns are detected as potential signs of changing health. We first present results of a preliminary study investigating 22 features extracted from in-home sensor data. A 1-D alert algorithm was then implemented to generate health alerts to clinicians in a senior housing facility. Clinicians analyze each alert and provide a rating on the clinical relevance. These ratings are then used as ground truth for training and testing classifiers. Here, we present the methodology for four classification approaches that fuse multisensor data. Results are shown using embedded sensor data and health alert ratings collected on 21 seniors over nine months. The best results show similar performance for two techniques, where one approach uses only domain knowledge and the second uses supervised learning for training. Finally, we propose a health change detection model based on these results and clinical expertise. The system of in-home sensors and algorithms for automated health alerts provides a method for detecting health problems very early so that early treatment is possible. This method of passive in-home sensing alleviates compliance issues. PMID:27170900

  5. A Trajectory-Based Coverage Assessment Approach for Universal Sensor Networks

    PubMed Central

    Qin, Ningning; Zheng, Xin; Tian, Guiyun

    2015-01-01

    To solve the problem of coverage performance assessment, this study proposes an evaluation method based on the trajectory of the target, which is applicable to universal sensor networks, including both heterogeneous and homogeneous sensor networks. Different from the traditional Voronoi algorithm, the proposed Improved Coverage Force Division (ICFD) plans a coverage force division map whichscales the qualitative coverage performancebasedon both covering intensities andlocations of the nodes. Furthermore, the Trajectory-based Evaluating Schedule (TES) is responsible for solving the quantitative coverage evaluationproblem by measuringthe resulting trajectories’ Balance Values (BVs). A model of weak-point ranking conjoined in consideration of coverage force and distance can guide future deployment to compensate coverage. Comparative trials using the greedy algorithm, Voronoi algorithm, and the proposed TES verify that TES achieves the approximate results for two-stage and multistage heterogeneous sensor networks with acceptable difference and lower complexity, and it is superior to the Voronoi algorithm in homogeneous sensor networks interms of breaking the four-point circle block. PMID:26270667

  6. Swath width study. A simulation assessment of costs and benefits of a sensor system for agricultural application

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Satellites provide an excellent platform from which to observe crops on the scale and frequency required to provide accurate crop production estimates on a worldwide basis. Multispectral imaging sensors aboard these platforms are capable of providing data from which to derive acreage and production estimates. The issue of sensor swath width was examined. The quantitative trade trade necessary to resolve the combined issue of sensor swath width, number of platforms, and their orbits was generated and are included. Problems with different swath width sensors were analyzed and an assessment of system trade-offs of swath width versus number of satellites was made for achieving Global Crop Production Forecasting.

  7. Thermodynamic assessment of the oxygen rich U-Ce-O system

    NASA Astrophysics Data System (ADS)

    McMurray, J. W.; Hirooka, S.; Murakami, T.; Suzuki, K.; White, J. T.; Voit, S. L.; Nelson, A. T.; Slone, B. W.; Besmann, T. M.; McClellan, K. J.; Kato, M.

    2015-12-01

    A thermodynamic assessment of the U-Ce-O system was performed by combining the existing Calphad assessments of the U-O and Ce-O binaries. A compound energy formalism representation for the fluorite U1-yCeyO2±x and a partially ionic two-sublattice liquid model for U-Ce-O melt were developed to describe the ternary solutions. Oxygen potentials for U1-yCeyO2±x for 0.05, 0.20, 0.30, and 0.50 Ce metal fractions were measured from thermogravimetric analysis and used, along with other thermodynamic data reported in the literature, to optimize the adjustable parameters of the models for U1-yCeyO2±x and the U-Ce-O ternary liquid. In addition, the thermochemical behavior of U1-yCeyO2±x and U1-yPuyO2±x was compared in order to assess the suitability of using Ce as a surrogate for Pu in MOX fuel.

  8. Operational Safety Assessment of Turbo Generators with Wavelet Rényi Entropy from Sensor-Dependent Vibration Signals

    PubMed Central

    Zhang, Xiaoli; Wang, Baojian; Chen, Xuefeng

    2015-01-01

    With the rapid development of sensor technology, various professional sensors are installed on modern machinery to monitor operational processes and assure operational safety, which play an important role in industry and society. In this work a new operational safety assessment approach with wavelet Rényi entropy utilizing sensor-dependent vibration signals is proposed. On the basis of a professional sensor and the corresponding system, sensor-dependent vibration signals are acquired and analyzed by a second generation wavelet package, which reflects time-varying operational characteristic of individual machinery. Derived from the sensor-dependent signals’ wavelet energy distribution over the observed signal frequency range, wavelet Rényi entropy is defined to compute the operational uncertainty of a turbo generator, which is then associated with its operational safety degree. The proposed method is applied in a 50 MW turbo generator, whereupon it is proved to be reasonable and effective for operation and maintenance. PMID:25894934

  9. Operational safety assessment of turbo generators with wavelet Rényi entropy from sensor-dependent vibration signals.

    PubMed

    Zhang, Xiaoli; Wang, Baojian; Chen, Xuefeng

    2015-01-01

    With the rapid development of sensor technology, various professional sensors are installed on modern machinery to monitor operational processes and assure operational safety, which play an important role in industry and society. In this work a new operational safety assessment approach with wavelet Rényi entropy utilizing sensor-dependent vibration signals is proposed. On the basis of a professional sensor and the corresponding system, sensor-dependent vibration signals are acquired and analyzed by a second generation wavelet package, which reflects time-varying operational characteristic of individual machinery. Derived from the sensor-dependent signals' wavelet energy distribution over the observed signal frequency range, wavelet Rényi entropy is defined to compute the operational uncertainty of a turbo generator, which is then associated with its operational safety degree. The proposed method is applied in a 50 MW turbo generator, whereupon it is proved to be reasonable and effective for operation and maintenance. PMID:25894934

  10. Near-infrared spectroscopic assessment of oxygen delivery to free flaps on monkeys following vascular occlusions and inhalation of pure oxygen

    NASA Astrophysics Data System (ADS)

    Tian, Fenghua; Ding, Haishu; Cai, Zhigang; Wang, Guangzhi; Zhao, Fuyun

    2002-04-01

    In recent studies, near-infrared spectroscopy (NIRS) has been considered as a potentially ideal noninvasive technique for the postoperative monitoring of plastic surgery. In this study, free flaps were raised on rhesus monkeys' forearms and oxygen delivery to these flaps was monitored following vascular occlusions and inhalation of pure oxygen. Optical fibers were adopted in the probe of the oximeter so that the detection could be performed in reflectance mode. The distance between emitter and detector can be adjusted easily to achieve the best efficacy. Different and repeatable patterns of changes were measured following vascular occlusions (arterial occlusion, venous occlusion and total occlusion) on flaps. It is clear that the near-infrared spectroscopy is capable of postoperatively monitoring vascular problems in flaps. NIRS showed high sensitivity to detect the dynamic changes in flaps induced by inhalation of pure oxygen in this study. The experimental results indicated that it was potential to assess tissue viability utilizing the dynamic changes induced by a noninvasive stimulation. It may be a new assessing method that is rapid, little influenced by other factors and brings less discomfort to patients.

  11. Assessing locomotor skills development in childhood using wearable inertial sensor devices: the running paradigm.

    PubMed

    Masci, Ilaria; Vannozzi, Giuseppe; Bergamini, Elena; Pesce, Caterina; Getchell, Nancy; Cappozzo, Aurelio

    2013-04-01

    Objective quantitative evaluation of motor skill development is of increasing importance to carefully drive physical exercise programs in childhood. Running is a fundamental motor skill humans adopt to accomplish locomotion, which is linked to physical activity levels, although the assessment is traditionally carried out using qualitative evaluation tests. The present study aimed at investigating the feasibility of using inertial sensors to quantify developmental differences in the running pattern of young children. Qualitative and quantitative assessment tools were adopted to identify a skill-sensitive set of biomechanical parameters for running and to further our understanding of the factors that determine progression to skilled running performance. Running performances of 54 children between the ages of 2 and 12 years were submitted to both qualitative and quantitative analysis, the former using sequences of developmental level, the latter estimating temporal and kinematic parameters from inertial sensor measurements. Discriminant analysis with running developmental level as dependent variable allowed to identify a set of temporal and kinematic parameters, within those obtained with the sensor, that best classified children into the qualitative developmental levels (accuracy higher than 67%). Multivariate analysis of variance with the quantitative parameters as dependent variables allowed to identify whether and which specific parameters or parameter subsets were differentially sensitive to specific transitions between contiguous developmental levels. The findings showed that different sets of temporal and kinematic parameters are able to tap all steps of the transitional process in running skill described through qualitative observation and can be prospectively used for applied diagnostic and sport training purposes. PMID:23067877

  12. Validity of using a 3-dimensional PET scanner during inhalation of 15O-labeled oxygen for quantitative assessment of regional metabolic rate of oxygen in man

    NASA Astrophysics Data System (ADS)

    Hori, Yuki; Hirano, Yoshiyuki; Koshino, Kazuhiro; Moriguchi, Tetsuaki; Iguchi, Satoshi; Yamamoto, Akihide; Enmi, Junichiro; Kawashima, Hidekazu; Zeniya, Tsutomu; Morita, Naomi; Nakagawara, Jyoji; Casey, Michael E.; Iida, Hidehiro

    2014-09-01

    Use of 15O labeled oxygen (15O2) and positron emission tomography (PET) allows quantitative assessment of the regional metabolic rate of oxygen (CMRO2) in vivo, which is essential to understanding the pathological status of patients with cerebral vascular and neurological disorders. The method has, however, been challenging, when a 3D PET scanner is employed, largely attributed to the presence of gaseous radioactivity in the trachea and the inhalation system, which results in a large amount of scatter and random events in the PET assessment. The present study was intended to evaluate the adequacy of using a recently available commercial 3D PET scanner in the assessment of regional cerebral radioactivity distribution during an inhalation of 15O2. Systematic experiments were carried out on a brain phantom. Experiments were also performed on a healthy volunteer following a recently developed protocol for simultaneous assessment of CMRO2 and cerebral blood flow, which involves sequential administration of 15O2 and C15O2. A particular intention was to evaluate the adequacy of the scatter-correction procedures. The phantom experiment demonstrated that errors were within 3% at the practically maximum radioactivity in the face mask, with the greatest radioactivity in the lung. The volunteer experiment demonstrated that the counting rate was at peak during the 15O gas inhalation period, within a verified range. Tomographic images represented good quality over the entire FOV, including the lower part of the cerebral structures and the carotid artery regions. The scatter-correction procedures appeared to be important, particularly in the process to compensate for the scatter originating outside the FOV. Reconstructed images dramatically changed if the correction was carried out using inappropriate procedures. This study demonstrated that accurate reconstruction could be obtained when the scatter compensation was appropriately carried out. This study also suggested the

  13. A novel tiered sensor fusion approach for terrain characterization and safe landing assessment

    NASA Technical Reports Server (NTRS)

    Serrano, Navid; Bajracharya, Max; Howard, Ayanna; Seraji, Homayoun

    2005-01-01

    This paper presents a novel tiered sensor fusion methodology for real-time terrain safety assessment. A combination of active and passive sensors, specifically, radar, lidar, and camera, operate in three tiers according to their inherent ranges of operation. Low-level terrain features (e.g. slope, roughness) and high-level terrain features (e.g. hills, craters) are integrated using principles of reasoning under uncertainty. Three methodologies are used to infer landing safety: Fuzzy Reasoning, Probabilistic Reasoning, and Evidential Reasoning. The safe landing predictions from the three fusion engines are consolidated in a subsequent decision fusion stage aimed at combining the strengths of each fusion methodology. Results from simulated spacecraft descents are presented and discussed.

  14. Efficient assessment method of on-board modulation transfer function of optical remote sensing sensors.

    PubMed

    Li, Jin; Xing, Fei; Sun, Ting; You, Zheng

    2015-03-01

    Modulation transfer function (MTF) can be used to evaluate the imaging performance of on-board optical remote sensing sensors, as well as recover and restore images to improve imaging quality. Laboratory measurement approaches for MTF have achieved high precision. However, they are not yet suitable for on-board measurement. In this paper, a new five-step approach to calculate MTF of space optical remote sensing sensors is proposed. First, a pixel motion model is used to extract the conditional sub-frame images. Second, a mathematical morphology algorithm and a correlation-homomorphic filter algorithm are used to eliminate noise and enhance sub-frame image. Third, an image partial differentiation determines the accurate position of edge points. Fourth, a model optical function is used to build a high-resolution edge spread function. Finally, MTF is calculated by derivation and Fourier transform. The experiment shows that the assessment method of MTF is superior to others. PMID:25836841

  15. AISI/DOE Advanced Process Control Program Vol. 1 of 6: Optical Sensors and Controls for Improved Basic Oxygen Furnace Operations

    SciTech Connect

    Sarah Allendorf; David Ottesen; Donald Hardesty

    2002-01-31

    The development of an optical sensor for basic oxygen furnace (BOF) off-gas composition and temperature in this Advanced Process Control project has been a laboratory spectroscopic method evolve into a pre-commercialization prototype sensor system. The sensor simultaneously detects an infrared tunable diode laser ITDL beam transmitted through the process off-gas directly above the furnace mouth, and the infrared greybody emission from the particulate-laden off-gas stream. Following developmental laboratory and field-testing, the sensor prototype was successfully tested in four long-term field trials at Bethlehem Steel's Sparrows Point plant in Baltimore, MD> The resulting optical data were analyzed and reveal correlations with four important process variables: (1) bath turndown temperature; (2) carbon monoxide post-combustion control; (2) bath carbon concentration; and (4) furnace slopping behavior. The optical sensor measurement of the off-gas temperature is modestly correlated with bath turndown temperature. A detailed regression analysis of over 200 heats suggests that a dynamic control level of +25 Degree F can be attained with a stand-alone laser-based optical sensor. The ability to track off-gas temperatures to control post-combustion lance practice is also demonstrated, and may be of great use in optimizing post-combustion efficiency in electric furnace steelmaking operations. In addition to the laser-based absorption spectroscopy data collected by this sensor, a concurrent signal generated by greybody emission from the particle-laden off-gas was collected and analyzed. A detailed regression analysis shows an excellent correlation of a single variable with final bath turndown carbon concentration. Extended field trials in 1998 and early 1999 show a response range from below 0.03% to a least 0.15% carbon concentration with a precision of +0.0007%. Finally, a strong correlation between prolonged drops in the off-gas emission signal and furnace slopping events

  16. 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

    2014-02-01

    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. PMID:24317451

  17. Strong ligand-protein interactions revealed by ultrafast infrared spectroscopy of CO in the heme pocket of the oxygen sensor FixL.

    PubMed

    Nuernberger, Patrick; Lee, Kevin F; Bonvalet, Adeline; Bouzhir-Sima, Latifa; Lambry, Jean-Christophe; Liebl, Ursula; Joffre, Manuel; Vos, Marten H

    2011-11-01

    In heme-based sensor proteins, ligand binding to heme in a sensor domain induces conformational changes that eventually lead to changes in enzymatic activity of an associated catalytic domain. The bacterial oxygen sensor FixL is the best-studied example of these proteins and displays marked differences in dynamic behavior with respect to model globin proteins. We report a mid-IR study of the configuration and ultrafast dynamics of CO in the distal heme pocket site of the sensor PAS domain FixLH, employing a recently developed method that provides a unique combination of high spectral resolution and range and high sensitivity. Anisotropy measurements indicate that CO rotates toward the heme plane upon dissociation, as is the case in globins. Remarkably, CO bound to the heme iron is tilted by ~30° with respect to the heme normal, which contrasts to the situation in myoglobin and in present FixLH-CO X-ray crystal structure models. This implies protein-environment-induced strain on the ligand, which is possibly at the origin of a very rapid docking-site population in a single conformation. Our observations likely explain the unusually low affinity of FixL for CO that is at the origin of the weak ligand discrimination between CO and O(2). Moreover, we observe orders of magnitude faster vibrational relaxation of dissociated CO in FixL than in globins, implying strong interactions of the ligand with the distal heme pocket environment. Finally, in the R220H FixLH mutant protein, where CO is H-bonded to a distal histidine, we demonstrate that the H-bond is maintained during photolysis. Comparison with extensively studied globin proteins unveils a surprisingly rich variety in both structural and dynamic properties of the interaction of a diatomic ligand with the ubiquitous b-type heme-proximal histidine system in different distal pockets. PMID:21970443

  18. Bioaerosol standoff detection and correlation assessment with concentration and viability point sensors

    NASA Astrophysics Data System (ADS)

    Buteau, Sylvie; Simard, Jean-Robert; Rowsell, Susan; Roy, Gilles

    2010-10-01

    A standoff bioaerosol sensor based on intensified range-gated spectrometric detection of Laser Induced Fluorescence was used to spectrally characterize bioaerosol simulants during in-chamber and open-air releases at Suffield, Canada, in August 2008 from a standoff position. In total, 42 in-chamber Bacillus atrophaeus (formerly Bacillus subtilis var globigii; BG) cloud and 27 open-air releases of either BG, Pantoea agglomerans (formerly Erwinia herbicola; EH), MS2 and ovalbumin (OV) were generated. The clouds were refereed by different point sensors including Aerodynamic Particle Sizer (APS) and slit or impingers samplers. The APS monitored the particle size distribution and concentration and the samplers characterized the viable portion of the cloud. The extracted spectral signatures show robustness to different degree. The correlation assessment showed good results in most cases where the LIF signal to noise ratio was significant. The sensor 4σ sensitivity was evaluated to 1 300, 600, 100 and 30 ppl for BG, OV, MS2 and EH respectively. Correlation results are presented by plotting the SINBAHD metric versus the corresponding particle concentration, in which case, the obtained slope is proportional to the material fluorescence cross-section. The different acquired signal is hence compared in terms of their fluorescence cross-section additionally to their spectral characteristics.

  19. Experimental investigation of the effect of polymer matrices on polymer fibre optic oxygen sensors and their time response characteristics using a vacuum testing chamber and a liquid flow apparatus

    PubMed Central

    Chen, Rongsheng; Formenti, Federico; McPeak, Hanne; Obeid, Andrew N.; Hahn, Clive; Farmery, Andrew

    2016-01-01

    Very fast sensors that are able to track rapid changes in oxygen partial pressure (PO2) in the gas and liquid phases are increasingly required in scientific research – particularly in the life sciences. Recent interest in monitoring very fast changes in the PO2 of arterial blood in some respiratory failure conditions is one such example. Previous attempts to design fast intravascular electrochemical oxygen sensors for use in physiology and medicine have failed to meet the criteria that are now required in modern investigations. However, miniature photonic devices are capable of meeting this need. In this article, we present an inexpensive polymer type fibre-optic, oxygen sensor that is two orders of magnitude faster than conventional electrochemical oxygen sensors. It is constructed with biologically inert polymer materials and is both sufficiently small and robust for direct insertion in to a human artery. The sensors were tested and evaluated in both a gas testing chamber and in a flowing liquid test system. The results showed a very fast T90 response time, typically circa 20 ms when tested in the gas phase, and circa 100 ms in flowing liquid. PMID:26726286

  20. Radiometric, geometric, and image quality assessment of ALOS AVNIR-2 and PRISM sensors

    USGS Publications Warehouse

    Saunier, S.; Goryl, P.; Chander, G.; Santer, R.; Bouvet, M.; Collet, B.; Mambimba, A.; Kocaman, Aksakal S.

    2010-01-01

    The Advanced Land Observing Satellite (ALOS) was launched on January 24, 2006, by a Japan Aerospace Exploration Agency (JAXA) H-IIA launcher. It carries three remote-sensing sensors: 1) the Advanced Visible and Near-Infrared Radiometer type 2 (AVNIR-2); 2) the Panchromatic Remote-Sensing Instrument for Stereo Mapping (PRISM); and 3) the Phased-Array type L-band Synthetic Aperture Radar (PALSAR). Within the framework of ALOS Data European Node, as part of the European Space Agency (ESA), the European Space Research Institute worked alongside JAXA to provide contributions to the ALOS commissioning phase plan. This paper summarizes the strategy that was adopted by ESA to define and implement a data verification plan for missions operated by external agencies; these missions are classified by the ESA as third-party missions. The ESA was supported in the design and execution of this plan by GAEL Consultant. The verification of ALOS optical data from PRISM and AVNIR-2 sensors was initiated 4 months after satellite launch, and a team of principal investigators assembled to provide technical expertise. This paper includes a description of the verification plan and summarizes the methodologies that were used for radiometric, geometric, and image quality assessment. The successful completion of the commissioning phase has led to the sensors being declared fit for operations. The consolidated measurements indicate that the radiometric calibration of the AVNIR-2 sensor is stable and agrees with the Landsat-7 Enhanced Thematic Mapper Plus and the Envisat MEdium-Resolution Imaging Spectrometer calibration. The geometrical accuracy of PRISM and AVNIR-2 products improved significantly and remains under control. The PRISM modulation transfer function is monitored for improved characterization. ?? 2006 IEEE.

  1. Fall risks assessment among community dwelling elderly using wearable wireless sensors

    NASA Astrophysics Data System (ADS)

    Lockhart, Thurmon E.; Soangra, Rahul; Frames, Chris

    2014-06-01

    Postural stability characteristics are considered to be important in maintaining functional independence free of falls and healthy life style especially for the growing elderly population. This study focuses on developing tools of clinical value in fall prevention: 1) Implementation of sensors that are minimally obtrusive and reliably record movement data. 2) Unobtrusively gather data from wearable sensors from four community centers 3) developed and implemented linear and non-linear signal analysis algorithms to extract clinically relevant information using wearable technology. In all a total of 100 community dwelling elderly individuals (66 non-fallers and 34 fallers) participated in the experiment. All participants were asked to stand-still in eyes open (EO) and eyes closed (EC) condition on forceplate with one wireless inertial sensor affixed at sternum level. Participants' history of falls had been recorded for last 2 years, with emphasis on frequency and characteristics of falls. Any participant with at least one fall in the prior year were classified as faller and the others as non-faller. The results indicated several key factors/features of postural characteristics relevant to balance control and stability during quite stance and, showed good predictive capability of fall risks among older adults. Wearable technology allowed us to gather data where it matters the most to answer fall related questions, i.e. the community setting environments. This study opens new prospects of clinical testing using postural variables with a wearable sensor that may be relevant for assessing fall risks at home and patient environment in near future.

  2. Cerebral metabolic rate of oxygen (CMRO2) assessed by combined Doppler and spectroscopic OCT

    PubMed Central

    Chong, Shau Poh; Merkle, Conrad W.; Leahy, Conor; Srinivasan, Vivek J.

    2015-01-01

    A method of measuring cortical oxygen metabolism in the mouse brain that uses independent quantitative measurements of three key parameters: cerebral blood flow (CBF), arteriovenous oxygen extraction (OE), and hemoglobin concentration ([HbT]) is presented. Measurements were performed using a single visible light spectral/Fourier domain OCT microscope, with Doppler and spectroscopic capabilities, through a thinned-skull cranial window in the mouse brain. Baseline metabolic measurements in mice are shown to be consistent with literature values. Oxygen consumption, as measured by this method, did not change substantially during minor changes either in the fraction of inspired oxygen (FiO2) or in the fraction of inspired carbon dioxide (FiCO2), in spite of larger variations in oxygen saturations. This set of experiments supports, but does not prove, the validity of the proposed method of measuring brain oxygen metabolism. PMID:26504644

  3. Muscle oxygenation during exercise under hypoxic conditions assessed by spatially resolved broadband NIR spectroscopy

    NASA Astrophysics Data System (ADS)

    Geraskin, Dmitri; Platen, Petra; Franke, Julia; Andre, Christiane; Bloch, Wilhelm; Kohl-Bareis, Matthias

    2005-08-01

    Near-infrared spectroscopy (NIRS) is used for the non-invasive measurement of muscle oxygenation during an incremental cycle test in healthy volunteers. A broad band spatially resolved system is used that allows the reliability of current algorithms to be inspected with the main emphasis on tissue oxygen saturation (SO2) and oxygenated and deoxygenated haemoglobin concentrations. Physiological conditions were modulated by changing oxygen supply from normal (21 % O2 in inspired air) to conditions corresponding to 2000 and 4000 m altitude above sea level (15.4 and 11.9 % O2). Under these hypoxic conditions the decrease in SO2 with increased exercise power is highly correlated with the oxygen content of the inspired air. There is a clear correlation with physiological parameters (heart rate, pulse oxymetry, blood gas, lactate, spirometric data). Skin oxygenation parameters are compared to those of muscle.

  4. Geometric Quality Assessment of Bundle Block Adjusted Mulit- Sensor Satellite Imageries

    NASA Astrophysics Data System (ADS)

    Ghosh, S.; Bhawani Kumar, P. S.; Radhadevi, P. V.; Srinivas, V.; Saibaba, J.; Varadan, G.

    2014-11-01

    The integration of multi-sensor earth observation data belonging to same area has become one of the most important input for resource mapping and management. Geometric error and fidelity between adjacent scenes affects large-area digital mosaic if the images/ scenes are processed independently. A block triangulation approach "Bundle Block Adjustment (BBA)" system has been developed at ADRIN for combined processing of multi-sensor, multi-resolution satellite imagery to achieve better geometric continuity. In this paper we present the evaluation results of BBA software along with performance assessment and operational use of products thus generated. The application evaluation deals with functional aspects of block-adjustment of satellite imagery consisting of data from multiple sources, i.e. AWiFs, LISS-3, LISS-4 and Cartosat-1 in various combinations as single block. It has provision for automatic generation of GCPs and tie-points using image metafile/ Rational Polynomial Coefficient's (RPC's) and ortho/ merged/ mosaicked products generation. The study is carried out with datasets covering different terrain types (ranging from high mountainous area, moderately undulating terrain, coastal plain, agriculture fields, urban area and water-body) across Indian subcontinent with varying block sizes and spatial reference systems. Geometric accuracy assessment is carried out to figure out error propagation at scene based ortho/ merged products as well as block level. The experimental results confirm that pixel tagging, geometric fidelity and feature continuity across adjacent scenes as well as for multiple sensors reduced to a great extent, due to the high redundancy. The results demonstrate that it is one of the most affective geometric corrections for generating large area digital mosaic over High mountainous terrain using high resolution good swath satellite imagery, like Cartosat-1, with minimum human intervention.

  5. Oxygen respirometry to assess stability and maturity of composted municipal solid waste

    SciTech Connect

    Iannotti, D.A.; Grebus, M.E.; Toth, B.L.; Madden, L.V.; Hoitink, A.J.

    1994-11-01

    The stability and maturity of compost prepared from municipal solid waste (MSW) at a full-scale composting plant was assessed through chemical, physical, and biological assays. Respiration bioassays used to determine stability (O{sub 2} and CO{sub 2} respirometry) were sensitive to process control problems at the composting plant and indicated increasing stability with time. Radish (Raphanus sativus L.) and ryegrass (Lolium perenne L.) growth bioassays revealed that immature compost samples inhibited growth. Growth of ryegrass in potting mix prepared with cured compost not amended with fertilizer was enhanced as compared to a pest control. Garden cress (Lepidium sativum L.) seed germination, used as an indicator of phytotoxicity, revealed inhibition of germination at all compost maturity levels. The phytotoxicity was though to be salt-related. Spearman rank-order correlations demonstrated that O{sub 2} respirometry, water-soluble organic C, and the water extract organic C to organic N ratio, significantly correlated with compost age and best indicated an acceptable level of stability. Oxygen respirometry also best predicted the potential for ryegrass growth, and an acceptable level of compost maturity. 31 refs., 4 figs., 5 tabs.

  6. Automated Technology for In-home Fall Risk Assessment and Detection Sensor System

    PubMed Central

    Rantz, Marilyn J.; Skubic, Marjorie; Abbott, Carmen; Galambos, Colleen; Pak, Youngju; Ho, Dominic K.C.; Stone, Erik E.; Rui, Liyang; Back, Jessica; Miller, Steven J.

    2013-01-01

    Falls are a major problem for older adults. A continuous, unobtrusive, environmentally mounted in-home monitoring system that automatically detects when falls have occurred or when the risk of falling is increasing could alert health care providers and family members so they could intervene to improve physical function or mange illnesses that are precipitating falls. Researchers at the University of Missouri (MU)Center for Eldercare and Rehabilitation Technology are testing such sensor systems for fall risk assessment and detection in older adults’ apartments in a senior living community. Initial results comparing ground truth fall risk assessment data and GAITRite gait parameters with gait parameters captured from Mircosoft Kinect and Pulse-Dopplar radar are reported. PMID:23675644

  7. Fractal circuit sensors enable rapid quantification of biomarkers for donor lung assessment for transplantation

    PubMed Central

    Sage, Andrew T.; Besant, Justin D.; Mahmoudian, Laili; Poudineh, Mahla; Bai, Xiaohui; Zamel, Ricardo; Hsin, Michael; Sargent, Edward H.; Cypel, Marcelo; Liu, Mingyao; Keshavjee, Shaf; Kelley, Shana O.

    2015-01-01

    Biomarker profiling is being rapidly incorporated in many areas of modern medical practice to improve the precision of clinical decision-making. This potential improvement, however, has not been transferred to the practice of organ assessment and transplantation because previously developed gene-profiling techniques require an extended period of time to perform, making them unsuitable in the time-sensitive organ assessment process. We sought to develop a novel class of chip-based sensors that would enable rapid analysis of tissue levels of preimplantation mRNA markers that correlate with the development of primary graft dysfunction (PGD) in recipients after transplant. Using fractal circuit sensors (FraCS), three-dimensional metal structures with large surface areas, we were able to rapidly (<20 min) and reproducibly quantify small differences in the expression of interleukin-6 (IL-6), IL-10, and ATP11B mRNA in donor lung biopsies. A proof-of-concept study using 52 human donor lungs was performed to develop a model that was used to predict, with excellent sensitivity (74%) and specificity (91%), the incidence of PGD for a donor lung. Thus, the FraCS-based approach delivers a key predictive value test that could be applied to enhance transplant patient outcomes. This work provides an important step toward bringing rapid diagnostic mRNA profiling to clinical application in lung transplantation. PMID:26601233

  8. Humidity sensors applicative characteristics of granularized and porous Bi2O3 thin films prepared by oxygen plasma-assisted pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Tudorache, Florin; Petrila, Iulian; Condurache-Bota, Simona; Constantinescu, Catalin; Praisler, Mirela

    2015-01-01

    Pulsed laser ablation of pure bismuth targets in a plasma discharge followed by thermal treatment as preparation method for humidity high-sensitive bismuth trioxide thin films deposited onto Si/Pt substrates were analyzed. Several thin films were deposited at different substrate temperatures during the pulsed laser deposition namely between 300 °C and 600 °C. Near to the electrical investigation, the structure and the morphology of the films as keys features for water adsorption are thoroughly investigated and correlated with their sensitivity as humidity sensors. Thus, it has been found that strong granularized Bi2O3 thin films obtained through oxygen plasma-assisted pulsed laser deposition onto Si/Pt substrate at 500 °C provide the most interesting humidity sensing characteristics.

  9. A Portable Gas Sensor System for Environmental Monitoring and Malodours Control: Data Assessment of an Experimental Campaign

    NASA Astrophysics Data System (ADS)

    Penza, Michele; Suriano, Domenico; Cassano, Gennaro; Rossi, Riccardo; Alvisi, Marco; Pfister, Valerio; Trizio, Livia; Brattoli, Magda; Amodio, Martino; De Gennaro, Gianluigi

    2011-09-01

    A portable sensor-system based on solid-state gas sensors has been designed and implemented as proof-of-concept for environmental air-monitoring applications, malodours olfactometric control and landfill gas monitoring. Commercial gas sensors and nanotechnology sensors are arranged in a configuration of array for multisensing and multiparameter devices. Wireless sensors at low-cost are integrated to implement a portable and mobile node, that can be used as early-detection system in a distributed sensor network. Real-time and continuous monitoring of hazardous air-contaminants (NO2, CO, PAH, BTEX, etc.) has been performed in field measurements by comparison of chemical analyzers from environmental protection governmental agency (ARPA-Puglia). In addition, experimental campaigns of the integrated portable sensor-system have been realized for assessment of malodours emitted from an urban waste site. The results demonstrate that the sensor-system has a potential capacity for real-time measurements of air-pollutants, malodours from waste site, and control of landfill gas.

  10. Embedding inertial-magnetic sensors in everyday objects: Assessing spatial cognition in children

    PubMed Central

    Taffoni, Fabrizio; Formica, Domenico; Iverson, Jana; Sparaci, Laura; Keller, Flavio; Guglielmelli, Eugenio

    2013-01-01

    This paper describes an interdisciplinary approach to the assessment of children development of spatial cognition, with a focus on the technology. An instrumented toy (block-box) is presented which embeds magneto-inertial sensors for orientation tracking, specifically developed to assess the ability to insert objects into holes. The functional specifications are derived from experimental protocols devised by neuroscientists to assess spatial cognition skills in children. Technological choices are emphasized with respect to ecological requirements. Ad-hoc calibration procedures are presented which are suitable to unstructured environments. Preliminary results based on experimental trials carried out at a day-care on typically developing children (12–36 months old) show how the instrumented objects can be used effectively in a semi-automatic fashion (i.e., rater-independent) to derive accurate measurements such as orientation errors and insertion time which are relevant to the object insertion task. This study indicates that a technological approach to ecological assessment of spatial cognition in children is indeed feasible and maybe useful for identification and early assessment of developmental delay. PMID:22744786

  11. Operational calibration and validation of landsat data continuity mission (LDCM) sensors using the image assessment system (IAS)

    USGS Publications Warehouse

    Micijevic, Esad; Morfitt, Ron

    2010-01-01

    Systematic characterization and calibration of the Landsat sensors and the assessment of image data quality are performed using the Image Assessment System (IAS). The IAS was first introduced as an element of the Landsat 7 (L7) Enhanced Thematic Mapper Plus (ETM+) ground segment and recently extended to Landsat 4 (L4) and 5 (L5) Thematic Mappers (TM) and Multispectral Sensors (MSS) on-board the Landsat 1-5 satellites. In preparation for the Landsat Data Continuity Mission (LDCM), the IAS was developed for the Earth Observer 1 (EO-1) Advanced Land Imager (ALI) with a capability to assess pushbroom sensors. This paper describes the LDCM version of the IAS and how it relates to unique calibration and validation attributes of its on-board imaging sensors. The LDCM IAS system will have to handle a significantly larger number of detectors and the associated database than the previous IAS versions. An additional challenge is that the LDCM IAS must handle data from two sensors, as the LDCM products will combine the Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) spectral bands.

  12. TDLAS-based sensors for in situ measurement of syngas composition in a pressurized, oxygen-blown, entrained flow coal gasifier

    NASA Astrophysics Data System (ADS)

    Sur, Ritobrata; Sun, Kai; Jeffries, Jay B.; Hanson, Ronald K.; Pummill, Randy J.; Waind, Travis; Wagner, David R.; Whitty, Kevin J.

    2014-07-01

    Tunable diode laser absorption spectroscopy based in situ sensors for CO (2.33 μm), CO2 (2.02 μm), CH4 (2.29 μm) and H2O (1.35 μm) were deployed in a pilot-scale (1 ton/day), high-pressure (up to 18 atm), entrained flow, oxygen-blown, slagging coal gasifier at the University of Utah. Measurements of species mole fraction with 3-s time resolution were taken at the pre- and post-filtration stages of the gasifier synthesis gas (called here syngas) output flow. Although particulate scattering makes pre-filter measurements more difficult, this location avoids the time delay of flow through the filtration devices. With the measured species and known N2 concentrations, the H2 content was obtained via balance. The lower heating value and the Wobbe index of the gas mixture were estimated using the measured gas composition. The sensors demonstrated here show promise for monitoring and control of the gasification process.

  13. Assessing benthic oxygen fluxes in oligotrophic deep sea sediments (HAUSGARTEN observatory)

    NASA Astrophysics Data System (ADS)

    Donis, Daphne; McGinnis, Daniel F.; Holtappels, Moritz; Felden, Janine; Wenzhoefer, Frank

    2016-05-01

    Benthic oxygen fluxes, an established proxy for total organic carbon mineralization, were investigated in oligotrophic deep sea sediments. We used three different in situ technologies to estimate the benthic oxygen fluxes at an Arctic deep sea site (2500 m depth, HAUSGARTEN observatory) with limiting conditions of low oxygen gradients and fluxes, low turbulence and low particle content in the benthic boundary layer. The resolved eddy covariance turbulent oxygen flux (-0.9±0.2 (SD) mmol O2 m-2 d-1) compared well with simultaneous dissolved oxygen flux measurements carried out with a microprofiler (-1.02±0.3 (SD) mmol O2 m-2 d-1) and total oxygen uptake obtained by benthic chamber incubations (-1.1±0.1 (SD) mmol O2 m-2 d-1). The agreement between these different techniques revealed that microbial-mediated oxygen consumption was dominant at this site. The average benthic flux equals a carbon mineralization rate of 4.3 g C m-2 yr-1, which exceeds the annual sedimentation of particulate organic matter measured by sediment traps. The present study represents a detailed comparison of different in situ technologies for benthic flux measurements at different spatial scales in oligotrophic deep sea sediments. The use of eddy covariance, so far rarely used for deep sea investigations, is presented in detail.

  14. Using vanadium in spinel as a sensor of oxygen fugacity in meteorites: Applications to Mars, Vesta, and other asteroids.

    SciTech Connect

    Righter, K.; Sutton, S.; Danielson, L.; Pando, K.; Le, L.; Newville, M.

    2009-03-23

    Some meteorites do not contain mineral assemblages required to apply traditional oxy-barometers. Here we introduce a technique using vanadium X-ray absorption features in spinels to characterize the oxygen fugacity of meteoritic dunites, pyroxenites, and chondrites. Igneous and metamorphic rocks commonly contain a mineral assemblage that allows oxygen fugacity to be calculated or constrained such as FeTi oxides, olivine-opx-spinel, or some other oxybarometer. Some rocks, however, contain a limited mineral assemblage and do not provide constraints on fO{sub 2} using mineral equilibria. Good examples of the latter are orthopyroxenites or dunites, such as diogenites, ALH 84001, chassignites, or brachinites. In fact it is no surprise that the fO{sub 2} of many of these samples is not well known, other than being 'reduced' and below the metal saturation value. In order to bridge this gap in our understanding, we have initiated a study of V in chromites in natural meteorite samples. Because the V pre-edge peak intensity and energy in chromites varies with fO{sub 2}, and this has been calibrated over a large fO{sub 2} range, we can apply this relation to rocks for which we otherwise have no fO{sub 2} constraints.

  15. Validation and calibration of a TDLAS oxygen sensor for in-line measurement on flow-packed products

    NASA Astrophysics Data System (ADS)

    Cocola, L.; Fedel, M.; Allermann, H.; Landa, S.; Tondello, G.; Bardenstein, A.; Poletto, L.

    2016-05-01

    A device based on Tunable Diode Laser Absorption Spectroscopy has been developed for non-invasive evaluation of gaseous oxygen concentration inside packed food containers. This work has been done in the context of the SAFETYPACK European project in order to enable full, automated product testing on a production line. The chosen samples at the end of the manufacturing process are modified atmosphere bags of processed mozzarella, in which the target oxygen concentration is required to be below 5%. The spectrometer allows in-line measurement of moving samples which are passing on a conveyor belt, with an optical layout optimized for bags made of a flexible scattering material, and works by sensing the gas phase in the headspace at the top of the package. A field applicable method for the calibration of this device has been identified and validated against traditional, industry standard, invasive measurement techniques. This allows some degrees of freedom for the end-user regarding packaging dimensions and shape. After deployment and setup of the instrument at the end-user manufacturing site, performance has been evaluated on a different range of samples in order to validate the choice of electro optical and geometrical parameters regarding sample handling and measurement timing at the actual measurement conditions.

  16. Investigation of source-detector separation optimization for an implantable perfusion and oxygenation sensor for liver blood vessels

    NASA Astrophysics Data System (ADS)

    Baba, J. S.; Akl, T. J.; Coté, G. L.; Wilson, M. A.; Ericson, M. N.

    2011-03-01

    An implanted system is being developed to monitor transplanted liver health during the critical 7-10 day period posttransplantation. The unit will monitor organ perfusion and oxygen consumption using optically-based probes placed on both the inflow and outflow blood vessels, and on the liver parenchymal surface. Sensing probes are based on a 3- wavelength LED source and a photodiode detector. Sample diffuse reflectance is measured at 735, 805, and 940 nm. To ascertain optimal source-to-photodetector spacing for perfusion measurement in blood vessels, an ex vivo study was conducted. In this work, a dye mixture simulating 80% blood oxygen saturation was developed and perfused through excised porcine arteries while collecting data for various preset probe source-to-photodetector spacings. The results from this study demonstrate a decrease in the optical signal with decreasing LED drive current and a reduction in perfusion index signal with increasing probe spacing. They also reveal a 2- to 4-mm optimal range for blood vessel perfusion probe source-to-photodetector spacing that allows for sufficient perfusion signal modulation depth with maximized signal to noise ratio (SNR). These findings are currently being applied to guide electronic configuration and probe placement for in vivo liver perfusion porcine model studies.

  17. Quantitative assessment of reactive oxygen species generation by cavitation incepted efficiently using nonlinear propagation effect

    NASA Astrophysics Data System (ADS)

    Yasuda, Jun; Yoshizawa, Shin; Umemura, Shin-ichiro

    2015-10-01

    Sonodynamic treatment is a treatment method that uses chemical bio-effect of cavitation bubbles. Reactive oxygen species that can kill cancerous tissue is induced by such chemical effect of cavitation bubbles and it is important to generate them efficiently for effective sonodynamic treatment. Cavitation cloud can be formed by an effect of nonlinear propagation and focus and in this study, it was experimentally investigated if cavitation cloud was useful for efficient generation of reactive oxygen species. As a result, it was demonstrated that cavitation cloud would be useful for efficient generation of reactive oxygen species.

  18. Assessing Impact of Dual Sensor Enhanced Flight Vision Systems on Departure Performance

    NASA Technical Reports Server (NTRS)

    Kramer, Lynda J.; Etherington, Timothy J.; Severance, Kurt; Bailey, Randall E.

    2016-01-01

    Synthetic Vision (SV) and Enhanced Flight Vision Systems (EFVS) may serve as game-changing technologies to meet the challenges of the Next Generation Air Transportation System and the envisioned Equivalent Visual Operations (EVO) concept - that is, the ability to achieve the safety and operational tempos of current-day Visual Flight Rules operations irrespective of the weather and visibility conditions. One significant obstacle lies in the definition of required equipage on the aircraft and on the airport to enable the EVO concept objective. A motion-base simulator experiment was conducted to evaluate the operational feasibility and pilot workload of conducting departures and approaches on runways without centerline lighting in visibility as low as 300 feet runway visual range (RVR) by use of onboard vision system technologies on a Head-Up Display (HUD) without need or reliance on natural vision. Twelve crews evaluated two methods of combining dual sensor (millimeter wave radar and forward looking infrared) EFVS imagery on pilot-flying and pilot-monitoring HUDs. In addition, the impact of adding SV to the dual sensor EFVS imagery on crew flight performance and workload was assessed. Using EFVS concepts during 300 RVR terminal operations on runways without centerline lighting appears feasible as all EFVS concepts had equivalent (or better) departure performance and landing rollout performance, without any workload penalty, than those flown with a conventional HUD to runways having centerline lighting. Adding SV imagery to EFVS concepts provided situation awareness improvements but no discernible improvements in flight path maintenance.

  19. A Microwave Ring-Resonator Sensor for Non-Invasive Assessment of Meat Aging

    PubMed Central

    Jilani, Muhammad Taha; Wen, Wong Peng; Cheong, Lee Yen; ur Rehman, Muhammad Zaka

    2016-01-01

    The assessment of moisture loss from meat during the aging period is a critical issue for the meat industry. In this article, a non-invasive microwave ring-resonator sensor is presented to evaluate the moisture content, or more precisely water holding capacity (WHC) of broiler meat over a four-week period. The developed sensor has shown significant changes in its resonance frequency and return loss due to reduction in WHC in the studied duration. The obtained results are also confirmed by physical measurements. Further, these results are evaluated using the Fricke model, which provides a good fit for electric circuit components in biological tissue. Significant changes were observed in membrane integrity, where the corresponding capacitance decreases 30% in the early aging (0D-7D) period. Similarly, the losses associated with intracellular and extracellular fluids exhibit changed up to 42% and 53%, respectively. Ultimately, empirical polynomial models are developed to predict the electrical component values for a better understanding of aging effects. The measured and calculated values are found to be in good agreement. PMID:26805828

  20. A Microwave Ring-Resonator Sensor for Non-Invasive Assessment of Meat Aging.

    PubMed

    Jilnai, Muhammad Taha; Wen, Wong Peng; Cheong, Lee Yen; ur Rehman, Muhammad Zaka

    2016-01-01

    The assessment of moisture loss from meat during the aging period is a critical issue for the meat industry. In this article, a non-invasive microwave ring-resonator sensor is presented to evaluate the moisture content, or more precisely water holding capacity (WHC) of broiler meat over a four-week period. The developed sensor has shown significant changes in its resonance frequency and return loss due to reduction in WHC in the studied duration. The obtained results are also confirmed by physical measurements. Further, these results are evaluated using the Fricke model, which provides a good fit for electric circuit components in biological tissue. Significant changes were observed in membrane integrity, where the corresponding capacitance decreases 30% in the early aging (0D-7D) period. Similarly, the losses associated with intracellular and extracellular fluids exhibit changed up to 42% and 53%, respectively. Ultimately, empirical polynomial models are developed to predict the electrical component values for a better understanding of aging effects. The measured and calculated values are found to be in good agreement. PMID:26805828

  1. Kinetic Investigations of the Role of Factor Inhibiting Hypoxia-inducible Factor (FIH) as an Oxygen Sensor*

    PubMed Central

    Tarhonskaya, Hanna; Hardy, Adam P.; Howe, Emily A.; Loik, Nikita D.; Kramer, Holger B.; McCullagh, James S. O.; Schofield, Christopher J.; Flashman, Emily

    2015-01-01

    The hypoxia-inducible factor (HIF) hydroxylases regulate hypoxia sensing in animals. In humans, they comprise three prolyl hydroxylases (PHD1–3 or EGLN1–3) and factor inhibiting HIF (FIH). FIH is an asparaginyl hydroxylase catalyzing post-translational modification of HIF-α, resulting in reduction of HIF-mediated transcription. Like the PHDs, FIH is proposed to have a hypoxia-sensing role in cells, enabling responses to changes in cellular O2 availability. PHD2, the most important human PHD isoform, is proposed to be biochemically/kinetically suited as a hypoxia sensor due to its relatively high sensitivity to changes in O2 concentration and slow reaction with O2. To ascertain whether these parameters are conserved among the HIF hydroxylases, we compared the reactions of FIH and PHD2 with O2. Consistent with previous reports, we found lower Kmapp(O2) values for FIH than for PHD2 with all HIF-derived substrates. Under pre-steady-state conditions, the O2-initiated FIH reaction is significantly faster than that of PHD2. We then investigated the kinetics with respect to O2 of the FIH reaction with ankyrin repeat domain (ARD) substrates. FIH has lower Kmapp(O2) values for the tested ARDs than HIF-α substrates, and pre-steady-state O2-initiated reactions were faster with ARDs than with HIF-α substrates. The results correlate with cellular studies showing that FIH is active at lower O2 concentrations than the PHDs and suggest that competition between HIF-α and ARDs for FIH is likely to be biologically relevant, particularly in hypoxic conditions. The overall results are consistent with the proposal that the kinetic properties of individual oxygenases reflect their biological capacity to act as hypoxia sensors. PMID:26112411

  2. A data fusion algorithm for multi-sensor microburst hazard assessment

    NASA Technical Reports Server (NTRS)

    Wanke, Craig R.; Hansman, R. John

    1994-01-01

    A recursive model-based data fusion algorithm for multi-sensor microburst hazard assessment is described. An analytical microburst model is used to approximate the actual windfield, and a set of 'best' model parameters are estimated from measured winds. The winds corresponding to the best parameter set can then be used to compute alerting factors such as microburst position, extent, and intensity. The estimation algorithm is based on an iterated extended Kalman filter which uses the microburst model parameters as state variables. Microburst state dynamic and process noise parameters are chosen based on measured microburst statistics. The estimation method is applied to data from a time-varying computational simulation of a historical microburst event to demonstrate its capabilities and limitations. Selection of filter parameters and initial conditions is discussed. Computational requirements and datalink bandwidth considerations are also addressed.

  3. Quality Assessment of 3d Reconstruction Using Fisheye and Perspective Sensors

    NASA Astrophysics Data System (ADS)

    Strecha, C.; Zoller, R.; Rutishauser, S.; Brot, B.; Schneider-Zapp, K.; Chovancova, V.; Krull, M.; Glassey, L.

    2015-03-01

    Recent mathematical advances, growing alongside the use of unmanned aerial vehicles, have not only overcome the restriction of roll and pitch angles during flight but also enabled us to apply non-metric cameras in photogrammetric method, providing more flexibility for sensor selection. Fisheye cameras, for example, advantageously provide images with wide coverage; however, these images are extremely distorted and their non-uniform resolutions make them more difficult to use for mapping or terrestrial 3D modelling. In this paper, we compare the usability of different camera-lens combinations, using the complete workflow implemented in Pix4Dmapper to achieve the final terrestrial reconstruction result of a well-known historical site in Switzerland: the Chillon Castle. We assess the accuracy of the outcome acquired by consumer cameras with perspective and fisheye lenses, comparing the results to a laser scanner point cloud.

  4. Recent trends in reinforcement corrosion assessment using piezo sensors via electro mechanical impedance technique

    NASA Astrophysics Data System (ADS)

    Visalakshi, Talakokula; Bhalla, Suresh; Gupta, Ashok; Bhattacharjee, Bishwajit

    2014-03-01

    Reinforced concrete (RC) is an economical, versatile and successful construction material as it can be moulded into a variety of shapes and finishes. In most cases, it is durable and strong, performing well throughout its service life. However, in some cases, it does not perform adequately due to various reasons, one of which is the corrosion of the embedded steel bars used as reinforcement. . Although the electro-mechanical impedance (EMI) technique is well established for damage detection and quantification of civil, mechanical and aerospace structures, only limited studies have been reported of its application for rebar corrosion detection in RC structures. This paper presents the recent trends in corrosion assessment based on the model derived from the equivalent structural parameters extracted from the impedance spectrum of concrete-rebar system using the lead zirconate titanate (PZT) sensors via EMI technique.

  5. Assessing surface properties of the Greenland ice sheet from multi-sensor optical remote sensing

    NASA Astrophysics Data System (ADS)

    Lhermitte, Stef; Van Lipzig, Nicole

    2015-04-01

    Assessment of the spatio-temporal variations in surface properties of the Greenland ice sheet provides valuable input for various applications ranging from energy and mass budget calculations to climate model validation. Within this context a variety of retrieval methods has been developed to assess surface properties from multi-spectral satellite sensors (e.g. Landsat, MODIS, …) . These methods range from multi-spectral classification to combined approaches that incorporate radiative transfer calculations. This study provides a quantitative analysis of the trade-offs between the state-of-the-art retrieval methodologies for assessing the surface properties of the Greenland ice sheet. Within this context, spatio-temporal patterns of surface properties (e.g., albedo, grain size, impurity load, ponding melt water, snow/ice classification) are derived from Landsat and MODIS reflectance data over the Greenland ice sheet from 2000 to present. The retrieved properties are subsequently compared and validated based on reference measurements. Analysis of the differences in derived surface properties from Landsat and MODIS reveals the importance of understanding the spatial and temporal scales at which variations occur. Large spatial variability within a MODIS pixel complicates the performance of retrieval methods for MODIS time series, especially in the ablation region, where the surface is very heterogeneous. Large temporal variability, on the other hand, constrains the validity of time series of Landsat retrievals and also has a large impact on the use of multi-day composite MODIS data.

  6. Assessing the oxygen stoichiometry during the sintering of (U, Pu)O2 fuel

    NASA Astrophysics Data System (ADS)

    Vaudez, Stéphane; Léchelle, Jacques; Berzati, Ségolène; Heintz, Jean-Marc

    2015-05-01

    Diffusion phenomena occurring in ceramics such as (U, Pu)O2 during sintering are affected by the oxygen content in the atmosphere. The latter sets the nature and the concentration of point defects which govern diffusion mechanisms in the bulk of the material. The oxygen partial pressure, pO2, of the sintering gas in equilibrium with mixed oxide (MOX) pellets needs to be precisely controlled; otherwise it may induce a large dispersion in the critical parameters for fuel manufacturing (Gauche, 2013; Matzke, 1987). It is crucial to understand the relation between the sintering atmosphere and the fuel throughout the thermal cycle. In this study, the oxygen potential of the sintering gas was monitored by measuring the oxygen partial pressure (pO2) at the outlet of a dilatometer by means of a zirconia probe. Coupling the thermal cycle with an outlet gas pO2 measurement makes it possible to identify different redox phenomena. Variations in the oxygen stoichiometry can be determined during the sintering of (U, Pu)O2, as well as can its final O/M. Our results make it possible to recommend a sintering atmosphere and sintering thermal cycle in order to obtain an O/M ratio that is as close as possible to the target value.

  7. Assessing the Effects of Water Rights Purchases on Dissolved Oxygen, Stream Temperatures, and Fish Habitat

    NASA Astrophysics Data System (ADS)

    Mouzon, N. R.; Null, S. E.

    2014-12-01

    Human impacts from land and water development have degraded water quality and altered the physical, chemical, and biological integrity of Nevada's Walker River. Reduced instream flows and increased nutrient concentrations affect native fish populations through warm daily stream temperatures and low nightly dissolved oxygen concentrations. Water rights purchases are being considered to maintain instream flows, improve water quality, and enhance habitat for native fish species, such as Lahontan cutthroat trout. This study uses the River Modeling System (RMSv4), an hourly, physically-based hydrodynamic and water quality model, to estimate streamflows, temperatures, and dissolved oxygen concentrations in the Walker River. We simulate thermal and dissolved oxygen changes from increased streamflow to prioritize the time periods and locations that water purchases most enhance native trout habitat. Stream temperatures and dissolved oxygen concentrations are proxies for trout habitat. Monitoring results indicate stream temperature and dissolved oxygen limitations generally exist in the 115 kilometers upstream of Walker Lake (about 37% of the study area) from approximately May through September, and this reach currently acts as a water quality barrier for fish passage.

  8. Using Vanadium in Spinel as a Sensor of Oxygen Fugacity in Meteorites: Applications to Mars, Vesta, and Other Asteroids

    NASA Technical Reports Server (NTRS)

    Righter, K.; Sutton, S.; Danielson, L.; Le, L.; Newville, M.; Pando, K.

    2009-01-01

    Igneous and metamorphic rocks commonly contain a mineral assemblage that allows oxygen fugacity to be calculated or constrained such as FeTi oxides, olivine-opx-spinel, or some other oxybarometer [1]. Some rocks, however, contain a limited mineral assemblage and do not provide constraints on fO2 using mineral equilibria. Good examples of the latter are orthopyroxenites or dunites, such as diogenites, ALH 84001, chassignites, or brachinites. In fact it is no surprise that the fO2 of many of these samples is not well known, other than being "reduced" and below the metal saturation value. In order to bridge this gap in our understanding, we have initiated a study of V in chromites in natural meteorite samples. Because the V pre-edge peak intensity and energy in chromites varies with fO2 (Fig. 1) [2], and this has been calibrated over a large fO 2 range, we can apply this relation to rocks for which we otherwise have no fO2 constraints.

  9. A preliminary assessment of oxygen isotope fractionation and growth increment periodicity in the estuarine clam Rangia cuneata

    NASA Astrophysics Data System (ADS)

    Andrus, C. Fred T.; Rich, Kelley Whatley

    2008-10-01

    Rangia cuneata is an upper estuarine clam common in the coastal regions of the Gulf of Mexico. Limited data exist regarding oxygen isotope fractionation and microstructural increment periodicity in this species. As these clams were recently identified as an invasive species in other regions, such data may be useful for environmental management purposes. Additionally, the shell of this clam is common in archeological middens, and thus may serve as a paleoenvironmental proxy. In order to assess these aspects of the species' natural history, samples were collected from the upper Mobile Bay, Alabama, USA. A stable oxygen isotope profile was generated from one of these valves, and compared to growth increments seen in thin section. Time-series water temperature data from near the collection site were used to construct idealized models of oxygen isotope variation, assuming equilibrium fractionation, constant shell growth, and stable water δ18O values. Comparison of the modeled and measured data suggest the shell was precipitated in, or near oxygen isotope equilibrium with ambient water, and that the microstructural increments in the shell were precipitated in response to tidal cycles.

  10. Assessing the performance of reactant transport layers and flow fields towards oxygen transport: A new imaging method based on chemiluminescence

    NASA Astrophysics Data System (ADS)

    Lopes, Thiago; Ho, Matthew; Kakati, Biraj K.; Kucernak, Anthony R. J.

    2015-01-01

    A new, simple and precise ex-situ optical imaging method is developed which allows indirect measurement of the partial pressure of oxygen (as ozone) within fuel cell components. Images of oxygen distribution are recorded with higher spatial (∼20 μm) and time (40 ms) resolutions. This approach is applied to assess oxygen concentration across the face of a pseudo polymer electrolyte fuel cell (PEFC), with a serpentine design flow field. We show that the amount of light produced is directly proportional to the partial pressure of ozone, in the same way as the local current density in a PEFC is proportional to the partial pressure of bimolecular oxygen. Hence the simulated system provides information relevant to a PEFC with the same geometry operating at the same stoichiometric ratio. This new approach allows direct imaging of flow under lands due to pressure gradients between the adjacent channels and non-laminar flow effects due to secondary flow around U-turns. These are major discoveries of fundamental importance in guiding materials development and in validating modelling studies. We find that contrary to many simulation papers, advection is an important mechanism in both the gas diffusion layer (more properly "reactant transport layer") and the microporous layer. Models which do not include these effects may underestimate reactant transport to the catalyst layer.

  11. Combination of spaceborne sensor(s) and 3-D aerosol models to assess global daily near-surface air quality

    NASA Astrophysics Data System (ADS)

    Kacenelenbogen, M.; Redemann, J.; Russell, P. B.

    2009-12-01

    Aerosol Particulate Matter (PM), measured by ground-based monitoring stations, is used as a standard by the EPA (Environmental Protection Agency) to evaluate daily air quality. PM monitoring is particularly important for human health protection because the exposure to suspended particles can contribute, among others, to lung and respiratory diseases and even premature death. However, most of the PM monitoring stations are located close to cities, leaving large areas without any operational data. Satellite remote sensing is well suited for a global coverage of the aerosol load and can provide an independent and supplemental data source to in situ monitoring. Nevertheless, PM at the ground cannot easily be determined from satellite AOD (Aerosol Optical Depth) without additional information on the optical/microphysical properties and vertical distribution of the aerosols. The objective of this study is to explore the efficacy and accuracy of combining a 3-D aerosol transport model and satellite remote sensing as a cost-effective approach for estimating ground-level PM on a global and daily basis. The estimation of the near-surface PM will use the vertical distribution (and, if possible, the physicochemical properties) of the aerosols inferred from a transport model and the measured total load of particles in the atmospheric column retrieved by satellite sensor(s). The first step is to select a chemical transport model (CTM) that provides “good” simulated aerosol vertical profiles. A few global (e.g., WRF-Chem-GOCART) or regional (e.g., MM5-CMAQ, PM-CAMx) CTM will be compared during selected airborne campaigns like ARCTAS-CARB (Arctic Research of the Composition of the Troposphere from Aircraft and Satellites- California Air Resources Board). The next step will be to devise an algorithm that combines the satellite and model data to infer PM mass estimates at the ground, after evaluating different spaceborne instruments and possible multi-sensor combinations.

  12. Iron-sulfur clusters as biological sensors: the chemistry of reactions with molecular oxygen and nitric oxide.

    PubMed

    Crack, Jason C; Green, Jeffrey; Thomson, Andrew J; Le Brun, Nick E

    2014-10-21

    Iron-sulfur cluster proteins exhibit a range of physicochemical properties that underpin their functional diversity in biology, which includes roles in electron transfer, catalysis, and gene regulation. Transcriptional regulators that utilize iron-sulfur clusters are a growing group that exploit the redox and coordination properties of the clusters to act as sensors of environmental conditions including O2, oxidative and nitrosative stress, and metabolic nutritional status. To understand the mechanism by which a cluster detects such analytes and then generates modulation of DNA-binding affinity, we have undertaken a combined strategy of in vivo and in vitro studies of a range of regulators. In vitro studies of iron-sulfur cluster proteins are particularly challenging because of the inherent reactivity and fragility of the cluster, often necessitating strict anaerobic conditions for all manipulations. Nevertheless, and as discussed in this Account, significant progress has been made over the past decade in studies of O2-sensing by the fumarate and nitrate reduction (FNR) regulator and, more recently, nitric oxide (NO)-sensing by WhiB-like (Wbl) and FNR proteins. Escherichia coli FNR binds a [4Fe-4S] cluster under anaerobic conditions leading to a DNA-binding dimeric form. Exposure to O2 converts the cluster to a [2Fe-2S] form, leading to protein monomerization and hence loss of DNA binding ability. Spectroscopic and kinetic studies have shown that the conversion proceeds via at least two steps and involves a [3Fe-4S](1+) intermediate. The second step involves the release of two bridging sulfide ions from the cluster that, unusually, are not released into solution but rather undergo oxidation to sulfane (S(0)) subsequently forming cysteine persulfides that then coordinate the [2Fe-2S] cluster. Studies of other [4Fe-4S] cluster proteins that undergo oxidative cluster conversion indicate that persulfide formation and coordination may be more common than previously

  13. Assessment of renal oxygenation during partial nephrectomy using DLP hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Best, Sara L.; Thapa, Abhas; Holzer, Michael S.; Jackson, Neil; Mir, Saad A.; Donnally, Chester J.; Wehner, Eleanor; Raj, Ganesh V.; Livingston, Edward; Cadeddu, Jeffrey A.; Zuzak, Karel J.

    2011-03-01

    Digital Light Processing (DLP®) hyperspectral imaging (HsI) is a non-invasive method used to construct a highly sensitive, real-time tissue oxygenation map through the measurement of the percentage of oxyhemoglobin. We have demonstrated that this technology can detect the oxyhemoglobin in the blood vessels on the surface of the kidney and we have used this to monitor renal perfusion during kidney cancer operations, where the blood supply to the kidney is interrupted for a period of time. This technology may allow us to "personalize" surgery based on the oxygenation profile.

  14. Optical Manufacturing and Testing Requirements Identified by the NASA Science Instruments, Observatories and Sensor Systems Technology Assessment

    NASA Technical Reports Server (NTRS)

    Stahl, H. Philip; Barney, Rich; Bauman, Jill; Feinberg, Lee; Mcleese, Dan; Singh, Upendra

    2011-01-01

    In August 2010, the NASA Office of Chief Technologist (OCT) commissioned an assessment of 15 different technology areas of importance to the future of NASA. Technology assessment #8 (TA8) was Science Instruments, Observatories and Sensor Systems (SIOSS). SIOSS assess the needs for optical technology ranging from detectors to lasers, x-ray mirrors to microwave antenna, in-situ spectrographs for on-surface planetary sample characterization to large space telescopes. The needs assessment looked across the entirety of NASA and not just the Science Mission Directorate. This paper reviews the optical manufacturing and testing technologies identified by SIOSS which require development in order to enable future NASA high priority missions.

  15. Bridge condition assessment from dynamic response collected using wireless sensor networks

    NASA Astrophysics Data System (ADS)

    Islam, A. K. M. Anwarul; Hamid, Hiwa F.; Li, Frank

    2014-03-01

    We propose dynamic response based condition assessment of prestressed box beam (PSBB) bridges that will be more realistic and cost-efficient. The hypothesis includes that the dynamic response is a sensitive indicator of the physical integrity and condition of a structure. We deployed two wireless sensor networks for collecting the real-time dynamic response of a 25-year old PSBB bridge under trucks with variable loads and speeds. The dynamic response of the bridge at its newest condition was collected from FE simulations of its 3-D FE models mimicking field conditions. The FE model was validated using experimental and theoretical methods. We used Fast Fourier Transform and peak-picking method to determine peak amplitudes and their corresponding fundamental frequencies at its newest and current condition. The analyses interestingly indicate a 37% reduction in its fundamental frequency over a 25-year service life. This reduction has been correlated to its current visual inspection to develop application software for quick and efficient condition assessment of PSBB bridges. The research outcome will provide an efficient and cost-effective solution for bridge inspection and maintenance.

  16. Vineyard zonal management for grape quality assessment by combining airborne remote sensed imagery and soil sensors

    NASA Astrophysics Data System (ADS)

    Bonilla, I.; Martínez De Toda, F.; Martínez-Casasnovas, J. A.

    2014-10-01

    Vineyard variability within the fields is well known by grape growers, producing different plant responses and fruit characteristics. Many technologies have been developed in last recent decades in order to assess this spatial variability, including remote sensing and soil sensors. In this paper we study the possibility of creating a stable classification system that better provides useful information for the grower, especially in terms of grape batch quality sorting. The work was carried out during 4 years in a rain-fed Tempranillo vineyard located in Rioja (Spain). NDVI was extracted from airborne imagery, and soil conductivity (EC) data was acquired by an EM38 sensor. Fifty-four vines were sampled at véraison for vegetative parameters and before harvest for yield and grape analysis. An Isocluster unsupervised classification in two classes was performed in 5 different ways, combining NDVI maps individually, collectively and combined with EC. The target vines were assigned in different zones depending on the clustering combination. Analysis of variance was performed in order to verify the ability of the combinations to provide the most accurate information. All combinations showed a similar behaviour concerning vegetative parameters. Yield parameters classify better by the EC-based clustering, whilst maturity grape parameters seemed to give more accuracy by combining all NDVIs and EC. Quality grape parameters (anthocyanins and phenolics), presented similar results for all combinations except for the NDVI map of the individual year, where the results were poorer. This results reveal that stable parameters (EC or/and NDVI all-together) clustering outcomes in better information for a vineyard zonal management strategy.

  17. Assessing Dual Sensor Enhanced Flight Vision Systems to Enable Equivalent Visual Operations

    NASA Technical Reports Server (NTRS)

    Kramer, Lynda J.; Etherington, Timothy J.; Severance, Kurt; Bailey, Randall E.; Williams, Steven P.; Harrison, Stephanie J.

    2016-01-01

    Flight deck-based vision system technologies, such as Synthetic Vision (SV) and Enhanced Flight Vision Systems (EFVS), may serve as a revolutionary crew/vehicle interface enabling technologies to meet the challenges of the Next Generation Air Transportation System Equivalent Visual Operations (EVO) concept - that is, the ability to achieve the safety of current-day Visual Flight Rules (VFR) operations and maintain the operational tempos of VFR irrespective of the weather and visibility conditions. One significant challenge lies in the definition of required equipage on the aircraft and on the airport to enable the EVO concept objective. A motion-base simulator experiment was conducted to evaluate the operational feasibility, pilot workload and pilot acceptability of conducting straight-in instrument approaches with published vertical guidance to landing, touchdown, and rollout to a safe taxi speed in visibility as low as 300 ft runway visual range by use of onboard vision system technologies on a Head-Up Display (HUD) without need or reliance on natural vision. Twelve crews evaluated two methods of combining dual sensor (millimeter wave radar and forward looking infrared) EFVS imagery on pilot-flying and pilot-monitoring HUDs as they made approaches to runways with and without touchdown zone and centerline lights. In addition, the impact of adding SV to the dual sensor EFVS imagery on crew flight performance, workload, and situation awareness during extremely low visibility approach and landing operations was assessed. Results indicate that all EFVS concepts flown resulted in excellent approach path tracking and touchdown performance without any workload penalty. Adding SV imagery to EFVS concepts provided situation awareness improvements but no discernible improvements in flight path maintenance.

  18. Vegetation productivity patterns at high northern latitudes: a multi-sensor satellite data assessment

    PubMed Central

    Guay, Kevin C; Beck, Pieter S A; Berner, Logan T; Goetz, Scott J; Baccini, Alessandro; Buermann, Wolfgang

    2014-01-01

    Satellite-derived indices of photosynthetic activity are the primary data source used to study changes in global vegetation productivity over recent decades. Creating coherent, long-term records of vegetation activity from legacy satellite data sets requires addressing many factors that introduce uncertainties into vegetation index time series. We compared long-term changes in vegetation productivity at high northern latitudes (>50°N), estimated as trends in growing season NDVI derived from the most widely used global NDVI data sets. The comparison included the AVHRR-based GIMMS-NDVI version G (GIMMSg) series, and its recent successor version 3g (GIMMS3g), as well as the shorter NDVI records generated from the more modern sensors, SeaWiFS, SPOT-VGT, and MODIS. The data sets from the latter two sensors were provided in a form that reduces the effects of surface reflectance associated with solar and view angles. Our analysis revealed large geographic areas, totaling 40% of the study area, where all data sets indicated similar changes in vegetation productivity over their common temporal record, as well as areas where data sets showed conflicting patterns. The newer, GIMMS3g data set showed statistically significant (α = 0.05) increases in vegetation productivity (greening) in over 15% of the study area, not seen in its predecessor (GIMMSg), whereas the reverse was rare (<3%). The latter has implications for earlier reports on changes in vegetation activity based on GIMMSg, particularly in Eurasia where greening is especially pronounced in the GIMMS3g data. Our findings highlight both critical uncertainties and areas of confidence in the assessment of ecosystem-response to climate change using satellite-derived indices of photosynthetic activity. Broader efforts are required to evaluate NDVI time series against field measurements of vegetation growth, primary productivity, recruitment, mortality, and other biological processes in order to better understand

  19. Vegetation productivity patterns at high northern latitudes: a multi-sensor satellite data assessment.

    PubMed

    Guay, Kevin C; Beck, Pieter S A; Berner, Logan T; Goetz, Scott J; Baccini, Alessandro; Buermann, Wolfgang

    2014-10-01

    Satellite-derived indices of photosynthetic activity are the primary data source used to study changes in global vegetation productivity over recent decades. Creating coherent, long-term records of vegetation activity from legacy satellite data sets requires addressing many factors that introduce uncertainties into vegetation index time series. We compared long-term changes in vegetation productivity at high northern latitudes (>50°N), estimated as trends in growing season NDVI derived from the most widely used global NDVI data sets. The comparison included the AVHRR-based GIMMS-NDVI version G (GIMMSg ) series, and its recent successor version 3g (GIMMS3g ), as well as the shorter NDVI records generated from the more modern sensors, SeaWiFS, SPOT-VGT, and MODIS. The data sets from the latter two sensors were provided in a form that reduces the effects of surface reflectance associated with solar and view angles. Our analysis revealed large geographic areas, totaling 40% of the study area, where all data sets indicated similar changes in vegetation productivity over their common temporal record, as well as areas where data sets showed conflicting patterns. The newer, GIMMS3g data set showed statistically significant (α = 0.05) increases in vegetation productivity (greening) in over 15% of the study area, not seen in its predecessor (GIMMSg ), whereas the reverse was rare (<3%). The latter has implications for earlier reports on changes in vegetation activity based on GIMMSg , particularly in Eurasia where greening is especially pronounced in the GIMMS3g data. Our findings highlight both critical uncertainties and areas of confidence in the assessment of ecosystem-response to climate change using satellite-derived indices of photosynthetic activity. Broader efforts are required to evaluate NDVI time series against field measurements of vegetation growth, primary productivity, recruitment, mortality, and other biological processes in order to better understand

  20. MRI assessment of changes in tumor oxygenation post hypoxia-targeted therapy

    NASA Astrophysics Data System (ADS)

    Agarwal, Shubhangi; Vidya Shankar, Rohini; Inge, Landon J.; Kodibagkar, Vikram

    2015-03-01

    In the tumor microenvironment, the combination of compromised oxygen supply and high demand results in formation of regions of acute and chronic hypoxia, which promotes metastasis, proliferation, resistance to chemo and radiotherapy and poor prognosis. Targeted, non-invasive in vivo imaging of hypoxia has the potential to determine regions with poor oxygenation in the target and differentiate between normoxic vs hypoxic tissues. MRI provides a powerful platform for generating quantitative maps of hypoxia with the use of a novel pO2 measuring technique PISTOL (Proton imaging of siloxanes to map tissue oxygenation levels) which could impact the therapeutic choices. In the present study, PISTOL was used to determine the changes in oxygenation of tumor in pre-clinical models of NSCLC (H1975) and epidermoid carcinoma (A431) in response to tirapzamine (TPZ), a hypoxia activated chemotherapeutic. The tumor volume measurements indicate that tirapazamine was more effective in slowing the tumor growth in H1975 as compared to A431 tumors, even though lower baseline pO2 was observed in A431 as compared to H1975 tumors. These results indicate that other factors such as tumor perfusion (essential for delivering TPZ) and relative expression of nitroreductases (essential for activating TPZ) may play an important role in conjunction with pO2.

  1. Wearable Sensor Use for Assessing Standing Balance and Walking Stability in People with Parkinson’s Disease: A Systematic Review

    PubMed Central

    Hubble, Ryan P.; Naughton, Geraldine A.; Silburn, Peter A.; Cole, Michael H.

    2015-01-01

    Background Postural instability and gait disability threaten the independence and well-being of people with Parkinson’s disease and increase the risk of falls and fall-related injuries. Prospective research has shown that commonly-used clinical assessments of balance and walking lack the sensitivity to accurately and consistently identify those people with Parkinson’s disease who are at a higher risk of falling. Wearable sensors provide a portable and affordable alternative for researchers and clinicians who are seeking to objectively assess movements and falls risk in the clinical setting. However, no consensus currently exists on the optimal placements for sensors and the best outcome measures to use for assessing standing balance and walking stability in Parkinson’s disease patients. Hence, this systematic review aimed to examine the available literature to establish the best sensor types, locations and outcomes to assess standing balance and walking stability in this population. Methods Papers listed in three electronic databases were searched by title and abstract to identify articles measuring standing balance or walking stability with any kind of wearable sensor among adults diagnosed with PD. To be eligible for inclusion, papers were required to be full-text articles published in English between January 1994 and December 2014 that assessed measures of standing balance or walking stability with wearable sensors in people with PD. Articles were excluded if they; i) did not use any form of wearable sensor to measure variables associated with standing balance or walking stability; ii) did not include a control group or control condition; iii) were an abstract and/or included in the proceedings of a conference; or iv) were a review article or case study. The targeted search of the three electronic databases identified 340 articles that were potentially eligible for inclusion, but following title, abstract and full-text review only 26 articles were deemed

  2. The Stroke Oxygen Study (SO2S) - a multi-center, study to assess whether routine oxygen treatment in the first 72 hours after a stroke improves long-term outcome: study protocol for a randomized controlled trial

    PubMed Central

    2014-01-01

    Background Mild hypoxia is common in stroke patients and may have significant adverse effects on the ischemic brain after stroke. The use of oxygen treatment is rapidly increasing in European stroke units but is not without side effects. It impedes early mobilization, could pose an infection risk, and may encourage the formation of toxic free radicals, leading to further damage to the ischemic brain. In the Stroke Oxygen Pilot Study (2 or 3 L/min for 72 hours) neurological recovery at one week was better in the oxygen group than in controls, and after correction for difference in baseline stroke severity and prognostic factors, there was a trend to better outcome with oxygen at six months. Oxygen was as effective in mild as in severe strokes. Oxygen saturation is lower at night than during the day, and episodes of oxygen desaturation are common during sleep. Nocturnal oxygen supplementation is likely to reduce the burden of hypoxia without interfering with daytime mobilization and rehabilitation. Before wider use of oxygen supplementation becomes established it is important to obtain better evidence on which patients benefit from such treatment. Methods Participants will be randomized to one of three groups: the first will receive continuous oxygen for 72 hours (at a rate of 2 or 3 L/min depending on baseline oxygen saturation), the second group will receive nocturnal oxygen only (at a rate of 2 or 3 L/min depending on baseline oxygen saturation) and the third group will not receive any oxygen (control). A baseline assessment is performed at randomization and a one-week follow-up completed. Outcome data at three, six and twelve months will be obtained via a questionnaire sent to the patient by the trial center. Discussion This study will provide evidence on the effectiveness of oxygen supplementation for the treatment of stroke and whether nocturnal oxygen is a potentially beneficial therapy regimen. Trial registration This trial is registered with the ISRCTN

  3. An innovative coupling between column leaching and oxygen consumption tests to assess behavior of contaminated marine dredged sediments.

    PubMed

    Couvidat, Julien; Benzaazoua, Mostafa; Chatain, Vincent; Zhang, Fan; Bouzahzah, Hassan

    2015-07-01

    Contaminated dredged sediments are often considered hazardous wastes, so they have to be adequately managed to avoid leaching of pollutants. The mobility of inorganic contaminants is a major concern. Metal sulfides (mainly framboïdal pyrite, copper, and zinc sulfides) have been investigated in this study as an important reactive metal-bearing phase sensitive to atmospheric oxygen action. An oxygen consumption test (OC-Test) has been adapted to assess the reactivity of dredged sediments when exposed to atmospheric oxygen. An experimental column set-up has been developed allowing the coupling between leaching and oxygen consumption test to investigate the reactivity of the sediment. This reactivity, which consisted of sulfide oxidation, was found to occur for saturation degree between 60 and 90 % and until the 20th testing week, through significant sulfates releases. These latter were assumed to come from sulfide oxidation in the first step of the test, then probably from gypsum dissolution. Confrontation results of OC-Test and leachate quality shows that Cu was well correlated to sulfates releases, which in turn, leads to Ca and Mg dissolution (buffer effect). Cu, and mostly Zn, was associated to organic matter, phyllosilicates, and other minerals through organo-clay complexes. This research confirmed that the OC-Test, originally developed for mine tailings, could be a useful tool in the dredged sediment field which can allow for intrinsic characterization of reactivity of a material suspected to readily reacting with oxygen and for better understanding of geochemical processes that affect pollutants behavior, conversion, and transfer in the environment. PMID:25779112

  4. Assessment of robustness against dissolved oxygen/substrate oscillations for C. glutamicum DM1933 in two-compartment bioreactor.

    PubMed

    Käß, Friedrich; Hariskos, Ioanna; Michel, Andrea; Brandt, Hans-Jürgen; Spann, Robert; Junne, Stefan; Wiechert, Wolfgang; Neubauer, Peter; Oldiges, Marco

    2014-06-01

    Corynebacterium glutamicum is an important organism for industrial biotechnology; particularly, in amino acid production (e.g. L-lysine). Production scales often reach reactor working volumes of several hundred cubic meters, which triggers inhomogeneous distribution of substrates and dissolved gasses due to increasing mixing times. Individual cells which follow the flow profile through the reactor are experiencing oscillating microenvironments. Oscillations can have an influence on the process performance, which is a subject of scale-down experiments. In this work, L-lysine-producing C. glutamicum DM1933 was assessed for its robustness against continuous dissolved oxygen and substrate supply oscillation in two-compartment scale-down bioreactors. Aerobic, substrate-limited stirred tank and non-aerated, substrate-excess plug flow compartments were applied for oscillation. Inhomogeneity of substrate and oxygen supply was observed to cause rapid side product turnover, redistribution of oxygen uptake from oxygen limited into fully aerobic zones, and intermediate medium acidification. However, process inhomogeneity did not impair productivity or growth at plug flow residence times of several minutes. In a focused analysis of proteome, metabolome, transcriptome, and other physiological parameters, no changes were identified in response to process inhomogeneity. In conclusion, fed-batch processes with C. glutamicum DM1933 possess remarkable robustness against oxygen and substrate supply oscillation, which is a unique property in the field of published scale-down studies. Microbial physiology of C. glutamicum appears to be ideally adapted to both homogeneous and inhomogeneous conditions. This ensures exceptional suitability for cultivation at increased mixing times, which is suggested to constitute an important basis for the long-lasting success in large scale bioprocess application. PMID:24218302

  5. Assessment of Lung Recruitment by Electrical Impedance Tomography and Oxygenation in ARDS Patients

    PubMed Central

    Yun, Long; He, Huai-wu; Möller, Knut; Frerichs, Inéz; Liu, Dawei; Zhao, Zhanqi

    2016-01-01

    Abstract We hypothesized that not all patients with appreciably recruited lung tissue during a recruitment maneuver (RM) show significant improvement of oxygenation. In the present study, we combined electrical impedance tomography (EIT) with oxygenation measurements to examine the discrepancies of lung ventilation and perfusion versus oxygenation after RM. A 2-minute RM (20 cm H2O positive end-expiratory pressure [PEEP] + 20 cm H2O pressure control) was prospectively conducted in 20 acute respiratory distress syndrome patients from January 2014 to December 2014. A decremental PEEP trial was performed to select the PEEP level after RM. A positive response to RM was identified as PaO2 + PaCO2 ≥400 mm Hg. Relative differences in the distribution of ventilation and perfusion in the most dependent region of interest (ROI4) were monitored with EIT and denoted as the ventilation-perfusion index. Ten patients were found to be responders and 10 patients to be nonresponders. No significant difference in baseline PaO2/FiO2 was observed between nonresponders and responders. A significantly higher PaO2/FiO2 ratio during RM and higher PEEP set after PEEP titration were recorded in responders. In both responders and nonresponders, the proportion of ventilation distributed in ROI4 compared with the global value was lower than the cardiac-related activity before RM, but this situation was reversed after RM (P < 0.01 in each group). Six out of 10 nonresponders exhibited a remarkable increase in ventilation in ROI4. A significant difference in the relative ventilation-perfusion index was found between the patients with remarkable and insufficient lung tissue reopening in the nonresponder group (P < 0.01). A discrepancy between lung tissue reopening and oxygenation improvement after RM was observed. EIT has the potential to evaluate the efficacy of RM by combining oxygenation measurements. PMID:27258527

  6. Assessment of Lung Recruitment by Electrical Impedance Tomography and Oxygenation in ARDS Patients.

    PubMed

    Yun, Long; He, Huai-Wu; Möller, Knut; Frerichs, Inéz; Liu, Dawei; Zhao, Zhanqi

    2016-05-01

    We hypothesized that not all patients with appreciably recruited lung tissue during a recruitment maneuver (RM) show significant improvement of oxygenation. In the present study, we combined electrical impedance tomography (EIT) with oxygenation measurements to examine the discrepancies of lung ventilation and perfusion versus oxygenation after RM.A 2-minute RM (20 cm H2O positive end-expiratory pressure [PEEP] + 20 cm H2O pressure control) was prospectively conducted in 20 acute respiratory distress syndrome patients from January 2014 to December 2014. A decremental PEEP trial was performed to select the PEEP level after RM. A positive response to RM was identified as PaO2 + PaCO2 ≥400 mm Hg. Relative differences in the distribution of ventilation and perfusion in the most dependent region of interest (ROI4) were monitored with EIT and denoted as the ventilation-perfusion index.Ten patients were found to be responders and 10 patients to be nonresponders. No significant difference in baseline PaO2/FiO2 was observed between nonresponders and responders. A significantly higher PaO2/FiO2 ratio during RM and higher PEEP set after PEEP titration were recorded in responders. In both responders and nonresponders, the proportion of ventilation distributed in ROI4 compared with the global value was lower than the cardiac-related activity before RM, but this situation was reversed after RM (P < 0.01 in each group). Six out of 10 nonresponders exhibited a remarkable increase in ventilation in ROI4. A significant difference in the relative ventilation-perfusion index was found between the patients with remarkable and insufficient lung tissue reopening in the nonresponder group (P < 0.01).A discrepancy between lung tissue reopening and oxygenation improvement after RM was observed. EIT has the potential to evaluate the efficacy of RM by combining oxygenation measurements. PMID:27258527

  7. Assessment of the Short-Term Radiometric Stability between Terra MODIS and Landsat 7 ETM+ Sensors

    NASA Technical Reports Server (NTRS)

    Choi, Taeyoung; Xiong, Xiaxiong; Chander, G.; Angal, Amit

    2009-01-01

    ) was included in the path of this continuous orbit, which served as a verification point between the shortterm and the long-term trending results from previous studies. This work focuses on monitoring the short-term on-orbit stability of MODIS and the ETM+ RSB. It also provides an assessment of the absolute calibration differences between the two sensors over their wide dynamic ranges.

  8. Development of a Mock Extracorporeal Membrane Oxygenation Circuit to Assess Recirculation.

    PubMed

    Jayewardene, Ishanth Devinda; Xie, Ashleigh; Iyer, Arjun; Pye, Roger; Dhital, Kumud

    2016-01-01

    A limitation of veno-venous extracorporeal membrane oxygenation (VV-ECMO) is the recirculating of newly oxygenated blood back to the VV-ECMO circuit. We compared cannulation strategies for combating recirculation utilizing a mock circulation loop (MCL) with ultrasonic flow probes and pressure transducers ensuring that the MCL was run at physiological hemodynamic parameters. Mean recirculation percentages were lower (ANOVA, F = 14.25; p = 0.0001) with the Wang-Zwische dual lumen cannula (4.00 ± 1.77, n = 7) than both the femoro-jugular (15.23 ± 7.00, n = 8) and the femoro-femoral cannulation configurations (13.49 ± 1.44, n = 8). PMID:26809084

  9. Retrieval of the photochemical reflectance index for assessing xanthophyll cycle activity: a comparison of near-surface optical sensors

    NASA Astrophysics Data System (ADS)

    Harris, A.; Gamon, J. A.; Pastorello, G. Z.; Wong, C. Y. S.

    2014-11-01

    Unattended optical sensors are increasingly being deployed on eddy covariance flux towers and are often used to complement existing vegetation and micrometeorological measurements to enable assessment of biophysical states and biogeochemical processes over a range of spatial scales. Of particular interest are sensors that can measure the photochemical reflectance index (PRI), which can provide information pertaining to leaf pigments and photosynthetic activity. This interest has facilitated the production of a new range of lower-cost multispectral sensors specifically designed to measure temporal changes in the PRI signal. However, little is known about the characteristics (spectral, radiometric and temporal) of many of these PRI sensors, making it difficult to compare data obtained from these sensors across time, geographical locations and instruments. Furthermore, direct testing of the capability of these sensors to actually detect the conversion of the xanthophyll cycle, which is the original biological basis of the PRI diurnal signal, is largely absent, often resulting in an unclear interpretation of the signal, particularly given the wide range of factors now known to influence PRI. Through a series of experiments, we assess the sensitivity of one of the leading brands of PRI sensor (Skye SKR 1800) to changes in vegetation photosynthetic activity in response to changing irradiance. We compare the results with those obtained using a more expensive industry-standard visible to near-infrared hyperspectral spectrometer (PP Systems UniSpec) and determine the radiometric compatibility of measurements made by the different instruments. Results suggest that the SKR 1800 instrument is able to track rapid (seconds to minutes) and more gradual diurnal changes in photosynthetic activity associated with xanthophyll cycle pigment conversion. Measurements obtained from both the high and lower cost instrument were significantly linearly correlated but were subject to a large

  10. a Meteorological Risk Assessment Method for Power Lines Based on GIS and Multi-Sensor Integration

    NASA Astrophysics Data System (ADS)

    Lin, Zhiyong; Xu, Zhimin

    2016-06-01

    Power lines, exposed in the natural environment, are vulnerable to various kinds of meteorological factors. Traditional research mainly deals with the influence of a single meteorological condition on the power line, which lacks of comprehensive effects evaluation and analysis of the multiple meteorological factors. In this paper, we use multiple meteorological monitoring data obtained by multi-sensors to implement the meteorological risk assessment and early warning of power lines. Firstly, we generate meteorological raster map from discrete meteorological monitoring data using spatial interpolation. Secondly, the expert scoring based analytic hierarchy process is used to compute the power line risk index of all kinds of meteorological conditions and establish the mathematical model of meteorological risk. By adopting this model in raster calculator of ArcGIS, we will have a raster map showing overall meteorological risks for power line. Finally, by overlaying the power line buffer layer to that raster map, we will get to know the exact risk index around a certain part of power line, which will provide significant guidance for power line risk management. In the experiment, based on five kinds of observation data gathered from meteorological stations in Guizhou Province of China, including wind, lightning, rain, ice, temperature, we carry on the meteorological risk analysis for the real power lines, and experimental results have proved the feasibility and validity of our proposed method.

  11. Upper Extremity 3D Reachable Workspace Assessment in ALS by Kinect sensor

    PubMed Central

    Oskarsson, Bjorn; Joyce, Nanette C.; de Bie, Evan; Nicorici, Alina; Bajcsy, Ruzena; Kurillo, Gregorij; Han, Jay J.

    2016-01-01

    Introduction Reachable workspace is a measure that provides clinically meaningful information regarding arm function. In this study, a Kinect sensor was used to determine the spectrum of 3D reachable workspace encountered in a cross-sectional cohort of individuals with ALS. Method Bilateral 3D reachable workspace was recorded from 10 subjects with ALS and 23 healthy controls. The data were normalized by each individual's arm length to obtain a reachable workspace relative surface area (RSA). Concurrent validity was assessed by correlation with ALSFRSr scores. Results The Kinect-measured reachable workspace RSA differed significantly between the ALS and control subjects (0.579±0.226 vs. 0.786±0.069; P<0.001). The RSA demonstrated correlation with ALSFRSr upper extremity items (Spearman correlation ρ=0.569; P=0.009). With worsening upper extremity function as categorized by the ALSFRSr, the reachable workspace also decreased progressively. Conclusions This study demonstrates the feasibility and potential of using a novel Kinect-based reachable workspace outcome measure in ALS. PMID:25965847

  12. Assessing post-anterior cruciate ligament reconstruction ambulation using wireless wearable integrated sensors.

    PubMed

    Arosha Senanayake, S M N; Ahmed Malik, Owais; Mohammad Iskandar, Pg; Zaheer, Dansih

    2013-11-01

    Abstract A hardware/software co-design for assessing post-Anterior Cruciate Ligament (ACL) reconstruction ambulation is presented. The knee kinematics and neuromuscular data during walking (2-6 km h(-1)) have been acquired using wireless wearable motion and electromyography (EMG) sensors, respectively. These signals were integrated by superimposition and mixed signals processing techniques in order to provide visual analyses of bio-signals and identification of the recovery progress of subjects. Monitoring overlapped signals simultaneously helps in detecting variability and correlation of knee joint dynamics and muscles activities for an individual subject as well as for a group. The recovery stages of subjects have been identified based on combined features (knee flexion/extension and EMG signals) using an adaptive neuro-fuzzy inference system (ANFIS). The proposed system has been validated for 28 test subjects (healthy and ACL-reconstructed). Results of ANFIS showed that the ambulation data can be used to distinguish subjects at different levels of recuperation after ACL reconstruction. PMID:24117351

  13. On-shoe wearable sensors for gait and turning assessment of patients with Parkinson's disease.

    PubMed

    Mariani, Benoit; Jiménez, Mayté Castro; Vingerhoets, François J G; Aminian, Kamiar

    2013-01-01

    Assessment of locomotion through simple tests such as timed up and go (TUG) or walking trials can provide valuable information for the evaluation of treatment and the early diagnosis of people with Parkinson's disease (PD). Common methods used in clinics are either based on complex motion laboratory settings or simple timing outcomes using stop watches. The goal of this paper is to present an innovative technology based on wearable sensors on-shoe and processing algorithm, which provides outcome measures characterizing PD motor symptoms during TUG and gait tests. Our results on ten PD patients and ten age-matched elderly subjects indicate an accuracy ± precision of 2.8 ± 2.4 cm/s and 1.3 ± 3.0 cm for stride velocity and stride length estimation compared to optical motion capture, with the advantage of being practical to use in home or clinics without any discomfort for the subject. In addition, the use of novel spatio-temporal parameters, including turning, swing width, path length, and their intercycle variability, was also validated and showed interesting tendencies for discriminating patients in ON and OFF states and control subjects. PMID:23268531

  14. Rapid high-throughput assessment of aerobic bacteria in complex samples by fluorescence-based oxygen respirometry.

    PubMed

    O'Mahony, Fiach C; Papkovsky, Dmitri B

    2006-02-01

    A simple method has been developed for the analysis of aerobic bacteria in complex samples such as broth and food homogenates. It employs commercial phosphorescent oxygen-sensitive probes to monitor oxygen consumption of samples containing bacteria using standard microtiter plates and fluorescence plate readers. As bacteria grow in aqueous medium, at certain points they begin to deplete dissolved oxygen, which is seen as an increase in probe fluorescence above baseline signal. The time required to reach threshold signal is used to either enumerate bacteria based on a predetermined calibration or to assess the effects of various effectors on the growth of test bacteria by comparison with an untreated control. This method allows for the sensitive (down to a single cell), rapid (0.5 to 12 h) enumeration of aerobic bacteria without the need to conduct lengthy (48 to 72 h) and tedious colony counts on agar plates. It also allows for screening a wide range of chemical and environmental samples for their toxicity. These assays have been validated with different bacteria, including Escherichia coli, Micrococcus luteus, and Pseudomonas fluorescens, with the enumeration of total viable counts in broth and industrial food samples (packaged ham, chicken, and mince meat), and comparison with established agar plating and optical-density-at-600-nm assays has been given. PMID:16461677

  15. Structural integrity and damage assessment of high performance arresting cable systems using an embedded distributed fiber optic sensor (EDIFOS) system

    NASA Astrophysics Data System (ADS)

    Mendoza, Edgar A.; Kempen, Cornelia; Sun, Sunjian; Esterkin, Yan; Prohaska, John; Bentley, Doug; Glasgow, Andy; Campbell, Richard

    2010-04-01

    Redondo Optics in collaboration with the Cortland Cable Company, TMT Laboratories, and Applied Fiber under a US Navy SBIR project is developing an embedded distributed fiber optic sensor (EDIFOSTM) system for the real-time, structural health monitoring, damage assessment, and lifetime prediction of next generation synthetic material arresting gear cables. The EDIFOSTM system represents a new, highly robust and reliable, technology that can be use for the structural damage assessment of critical cable infrastructures. The Navy is currently investigating the use of new, all-synthetic- material arresting cables. The arresting cable is one of the most stressed components in the entire arresting gear landing system. Synthetic rope materials offer higher performance in terms of the strength-to-weight characteristics, which improves the arresting gear engine's performance resulting in reduced wind-over-deck requirements, higher aircraft bring-back-weight capability, simplified operation, maintenance, supportability, and reduced life cycle costs. While employing synthetic cables offers many advantages for the Navy's future needs, the unknown failure modes of these cables remains a high technical risk. For these reasons, Redondo Optics is investigating the use of embedded fiber optic sensors within the synthetic arresting cables to provide real-time structural assessment of the cable state, and to inform the operator when a particular cable has suffered impact damage, is near failure, or is approaching the limit of its service lifetime. To date, ROI and its collaborators have developed a technique for embedding multiple sensor fibers within the strands of high performance synthetic material cables and use the embedded fiber sensors to monitor the structural integrity of the cable structures during tensile and compressive loads exceeding over 175,000-lbsf without any damage to the cable structure or the embedded fiber sensors.

  16. INTEGRATION OF HEAT CAPACITY AND ELECTRICAL CONDUCTIVITY SENSORS FOR ROOT MODULE WATER AND NUTRIENT ASSESSMENT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Management of water content and nutrient status during space flight is a critical necessity in plant production systems. Our objectives were to determine if dual-probe heat pulse sensors could improve water content determination accuracy over single-probe heat-pulse sensors, and to test a design usi...

  17. A Novel Pilot Study Using Spatial Frequency Domain Imaging to Assess Oxygenation of Perforator Flaps During Reconstructive Breast Surgery

    PubMed Central

    Nguyen, John T.; Lin, Samuel J.; Tobias, Adam M.; Gioux, Sylvain; Mazhar, Amaan; Cuccia, David J.; Ashitate, Yoshitomo; Stockdale, Alan; Oketokoun, Rafiou; Durr, Nicholas J.; Moffitt, Lorissa A.; Durkin, Anthony J.; Tromberg, Bruce J.; Frangioni, John V.; Lee, Bernard T.

    2013-01-01

    Introduction Although various methods exist for monitoring flaps during reconstructive surgery, surgeons primarily rely on assessment of clinical judgment. Early detection of vascular complications improves rate of flap salvage. Spatial frequency domain imaging (SFDI) is a promising new technology that provides oxygenation images over a large field of view. The goal of this clinical pilot study is to use SFDI in perforator flap breast reconstruction. Methods Three women undergoing unilateral breast reconstruction after mastectomy were enrolled for our study. The SFDI system was deployed in the operating room, and images acquired over the course of the operation. Time points included images of each hemiabdominal skin flap before elevation, the selected flap after perforator dissection, and after microsurgical transfer. Results Spatial frequency domain imaging was able to measure tissue oxy-hemoglobin concentration (ctO2Hb), tissue deoxyhemoglobin concentration, and tissue oxygen saturation (stO2). Images were created for each metric to monitor flap status and the results quantified throughout the various time points of the procedure. For 2 of 3 patients, the chosen flap had a higher ctO2Hb and stO2. For 1 patient, the chosen flap had lower ctO2Hb and stO2. There were no perfusion deficits observed based on SFDI and clinical follow-up. Conclusions The results of our initial human pilot study suggest that SFDI has the potential to provide intraoperative oxygenation images in real-time during surgery. With the use of this technology, surgeons can obtain tissue oxygenation and hemoglobin concentration maps to assist in intraoperative planning; this can potentially prevent complications and improve clinical outcome. PMID:23945533

  18. Simultaneous assessment of red blood cell aggregation and oxygen saturation under pulsatile flow using high-frequency photoacoustics

    PubMed Central

    Bok, Tae-Hoon; Hysi, Eno; Kolios, Michael C.

    2016-01-01

    We investigate the feasibility of photoacoustic (PA) imaging for assessing the correlation between red blood cell (RBC) aggregation and the oxygen saturation (sO2) in a simulated pulsatile blood flow system. For the 750 and 850 nm illuminations, the PA amplitude (PAA) increased and decreased as the mean blood flow velocity decreased and increased, respectively, at all beat rates (60, 120 and 180 bpm). The sO2 also cyclically varied, in phase with the PAA for all beat rates. However, the linear correlation between the sO2 and the PAA at 850 nm was stronger than that at 750 nm. These results suggest that the sO2 can be correlated with RBC aggregation induced by decreased mean shear rate in pulsatile flow, and that the correlation is dependent on the optical wavelength. The hemodynamic properties of blood flow assessed by PA imaging may be used to provide a new biomarker for simultaneous monitoring blood viscosity related to RBC aggregation, oxygen delivery related to the sO2 and their clinical correlation. PMID:27446705

  19. Simultaneous assessment of red blood cell aggregation and oxygen saturation under pulsatile flow using high-frequency photoacoustics.

    PubMed

    Bok, Tae-Hoon; Hysi, Eno; Kolios, Michael C

    2016-07-01

    We investigate the feasibility of photoacoustic (PA) imaging for assessing the correlation between red blood cell (RBC) aggregation and the oxygen saturation (sO2) in a simulated pulsatile blood flow system. For the 750 and 850 nm illuminations, the PA amplitude (PAA) increased and decreased as the mean blood flow velocity decreased and increased, respectively, at all beat rates (60, 120 and 180 bpm). The sO2 also cyclically varied, in phase with the PAA for all beat rates. However, the linear correlation between the sO2 and the PAA at 850 nm was stronger than that at 750 nm. These results suggest that the sO2 can be correlated with RBC aggregation induced by decreased mean shear rate in pulsatile flow, and that the correlation is dependent on the optical wavelength. The hemodynamic properties of blood flow assessed by PA imaging may be used to provide a new biomarker for simultaneous monitoring blood viscosity related to RBC aggregation, oxygen delivery related to the sO2 and their clinical correlation. PMID:27446705

  20. Health assessment of gasoline and fuel oxygenate vapors: micronucleus and sister chromatid exchange evaluations.

    PubMed

    Schreiner, Ceinwen A; Hoffman, Gary M; Gudi, Ramadevi; Clark, Charles R

    2014-11-01

    Micronucleus and sister chromatid exchange (SCE) tests were performed for vapor condensate of baseline gasoline (BGVC), or gasoline with oxygenates, methyl tert-butyl ether (G/MTBE), ethyl tert butyl ether (G/ETBE), t-amyl methyl ether (G/TAME), diisopropyl ether (G/DIPE), t-butyl alcohol (TBA), or ethanol (G/EtOH). Sprague Dawley rats (the same 5/sex/group for both endpoints) were exposed to 0, 2000, 10,000, or 20,000mg/m(3) of each condensate, 6h/day, 5days/week over 4weeks. Positive controls (5/sex/test) were given cyclophosphamide IP, 24h prior to sacrifice at 5mg/kg (SCE test) and 40mg/kg (micronucleus test). Blood was collected from the abdominal aorta for the SCE test and femurs removed for the micronucleus test. Blood cell cultures were treated with 5μg/ml bromodeoxyuridine (BrdU) for SCE evaluation. No significant increases in micronucleated immature erythrocytes were observed for any test material. Statistically significant increases in SCE were observed in rats given BGVC alone or in female rats given G/MTBE. G/TAME induced increased SCE in both sexes at the highest dose only. Although DNA perturbation was observed for several samples, DNA damage was not expressed as increased micronuclei in bone marrow cells. Inclusion of oxygenates in gasoline did not increase the effects of gasoline alone or produce a cytogenetic hazard. PMID:24852491

  1. Cell design concepts for aqueous lithium-oxygen batteries: A model-based assessment

    NASA Astrophysics Data System (ADS)

    Grübl, Daniel; Bessler, Wolfgang G.

    2015-11-01

    Seven cell design concepts for aqueous (alkaline) lithium-oxygen batteries are investigated using a multi-physics continuum model for predicting cell behavior and performance in terms of the specific energy and specific power. Two different silver-based cathode designs (a gas diffusion electrode and a flooded cathode) and three different separator designs (a porous separator, a stirred separator chamber, and a redox-flow separator) are compared. Cathode and separator thicknesses are varied over a wide range (50 μm-20 mm) in order to identify optimum configurations. All designs show a considerable capacity-rate effect due to spatiotemporally inhomogeneous precipitation of solid discharge product LiOH·H2O. In addition, a cell design with flooded cathode and redox-flow separator including oxygen uptake within the external tank is suggested. For this design, the model predicts specific power up to 33 W/kg and specific energy up to 570 Wh/kg (gravimetric values of discharged cell including all cell components and catholyte except housing and piping).

  2. Atomic Resolution of Calcium and Oxygen Sublattices of Calcite in Ambient Conditions by Atomic Force Microscopy Using qPlus Sensors with Sapphire Tips.

    PubMed

    Wastl, Daniel S; Judmann, Michael; Weymouth, Alfred J; Giessibl, Franz J

    2015-01-01

    Characterization and imaging at the atomic scale with atomic force microscopy in biocompatible environments is an ongoing challenge. We demonstrate atomically resolved imaging of the calcite (101̅4) surface plane using stiff quartz cantilevers ("qPlus sensors", stiffness k = 1280 N/m) equipped with sapphire tips in ambient conditions without any surface preparation. With 10 atoms in one surface unit cell, calcite has a highly complex surface structure comprising three different chemical elements (Ca, C, and O). We obtain true atomic resolution of calcite in air at relative humidity ranging from 20% to 40%, imaging atomic steps and single atomic defects. We observe a great durability of sapphire tips with their Mohs hardness of 9, only one step below diamond. Depending on the state of the sapphire tip, we resolve either the calcium or the oxygen sublattice. We determine the tip termination by comparing the experimental images with simulations and discuss the possibility of chemical tip identification in air. The main challenges for imaging arise from the presence of water layers, which form on almost all surfaces and have the potential to dissolve the crystal surface. Frequency shift versus distance spectra show the presence of at least three ordered hydration layers. The measured height of the first hydration layer corresponds well to X-ray diffraction data and molecular dynamic simulations, namely, ∼220 pm. For the following hydration layers we measure ∼380 pm for the second and third layer, ending up in a total hydration layer thickness of at least 1 nm. Understanding the influence of water layers and their structure is important for surface segregation, surface reactions including reconstructions, healing of defects, and corrosion. PMID:25816927

  3. Assessing the Performance of Sensor Fusion Methods: Application to Magnetic-Inertial-Based Human Body Tracking.

    PubMed

    Ligorio, Gabriele; Bergamini, Elena; Pasciuto, Ilaria; Vannozzi, Giuseppe; Cappozzo, Aurelio; Sabatini, Angelo Maria

    2016-01-01

    Information from complementary and redundant sensors are often combined within sensor fusion algorithms to obtain a single accurate observation of the system at hand. However, measurements from each sensor are characterized by uncertainties. When multiple data are fused, it is often unclear how all these uncertainties interact and influence the overall performance of the sensor fusion algorithm. To address this issue, a benchmarking procedure is presented, where simulated and real data are combined in different scenarios in order to quantify how each sensor's uncertainties influence the accuracy of the final result. The proposed procedure was applied to the estimation of the pelvis orientation using a waist-worn magnetic-inertial measurement unit. Ground-truth data were obtained from a stereophotogrammetric system and used to obtain simulated data. Two Kalman-based sensor fusion algorithms were submitted to the proposed benchmarking procedure. For the considered application, gyroscope uncertainties proved to be the main error source in orientation estimation accuracy for both tested algorithms. Moreover, although different performances were obtained using simulated data, these differences became negligible when real data were considered. The outcome of this evaluation may be useful both to improve the design of new sensor fusion methods and to drive the algorithm tuning process. PMID:26821027

  4. MEMS sensors for assessing flow-related control of an underwater biomimetic robotic stingray.

    PubMed

    Asadnia, Mohsen; Kottapalli, Ajay Giri Prakash; Haghighi, Reza; Cloitre, Audren; Alvarado, Pablo Valdivia Y; Miao, Jianmin; Triantafyllou, Michael

    2015-06-01

    A major difference between manmade underwater robotic vehicles (URVs) and undersea animals is the dense arrays of sensors on the body of the latter which enable them to execute extreme control of their limbs and demonstrate super-maneuverability. There is a high demand for miniaturized, low-powered, lightweight and robust sensors that can perform sensing on URVs to improve their control and maneuverability. In this paper, we present the design, fabrication and experimental testing of two types of microelectromechanical systems (MEMS) sensors that benefit the situational awareness and control of a robotic stingray. The first one is a piezoresistive liquid crystal polymer haircell flow sensor which is employed to determine the velocity of propagation of the stingray. The second one is Pb(Zr(0.52)Ti(0.48))O3 piezoelectric micro-diaphragm pressure sensor which measures various flapping parameters of the stingray's fins that are key parameters to control the robot locomotion. The polymer flow sensors determine that by increasing the flapping frequency of the fins from 0.5 to 3 Hz the average velocity of the stingray increases from 0.05 to 0.4 BL s(-1), respectively. The role of these sensors in detecting errors in control and functioning of the actuators in performing tasks like flapping at a desired amplitude and frequency, swimming at a desired velocity and direction are quantified. The proposed sensors are also used to provide inputs for a model predictive control which allows the robot to track a desired trajectory. Although a robotic stingray is used as a platform to emphasize the role of the MEMS sensors, the applications can be extended to most URVs. PMID:25984934

  5. Oxygen Isotope Anomaly in the Carbonate Fractions of Aerosols and its Potential to Assess Urban Pollution

    NASA Astrophysics Data System (ADS)

    Shaheen, R.; Abramian, A.; Dominguez, G.; Jackson, T.; Thiemens, M. H.

    2008-12-01

    Mineral dust is emitted into the atmosphere from arid regions in Asia yearly, accounting for ~36% of global aerosol emissions, 5900 Tg yr-1 [IPCC 2007]. Increasing anthropogenic emissions and persistent dust emissions not only have reduced the air quality in Asia itself, but are also affecting the pollutant deposition into the Pacific Ocean and air quality in downwind areas. The carbonate component of mineral dust (calcite (CaCO3) and dolomite (CaMg(CO3)2) is particularly reactive and can comprise as much as 30% of the total mineral dust aerosol, depending on the source region [Claquin et al., 1999]. Carbonate can affect atmospheric chemical processes and aerosol characteristics because the acid neutralizing capacity of this species facilitates the heterogeneous conversion of sulphate and nitrate. Understanding heterogeneous reactions occurring on the surface of aerosol particles will lead to a better understanding of the fate and transport of molecules in the troposphere as well as to resolve their role in air quality and pollution. The primary goal of this work is to develop an isotope methodology for carbonates that can be used as a chemical marker for the origin of polluted air plumes and chemical transformation during the long range transport of air masses. We will discuss the carbon and oxygen isotope composition of the CO2 released from the fine (< 1 μm) and coarse (> 1 μm) particles collected at two different sites [Mt. Soledad (800 ft) and Scripps Pier, La Jolla, California] and its possible utility as a tracer to identify the long-range transport of aerosol from local pollution events. The degree of urban influence of sampled air parcels at each site was quantified through back-trajectory analysis of NOAA HYSPLIT output data. Interestingly, the isotopes of oxygen did not follow standard mass dependent relationship (δ17O ~ 0.52 δ18O) rather have excess 17O (Δ17O = δ17O- 0.52δ18O) ranging from 0.9 to 3.9 per mil. A highly significant correlation (r2

  6. Seasonal Water Usage by Juniperus Ashei: Assessment With Stable Isotopes of Hydrogen and Oxygen

    NASA Astrophysics Data System (ADS)

    McCole, A. A.

    2003-12-01

    The recent expansion of Juniperus ashei (Ashe juniper) on the Edwards Plateau of Central Texas has important implications for the ecosystem structure, productivity and hydrology of the region. Ashe juniper expansion may negatively impact the ecology and hydrology of the Edwards Plateau. The Ashe juniper's morphology, rooting habit, and ability to photosynthesize throughout the year suggests greater water loss will occur in areas where Ashe juniper is prevalent compared to areas dominated by grasses. However, past studies have reached conflicting conclusions regarding Ashe juniper's effect on the water budget. A better understanding of the patterns of Ashe juniper's water use will aid in the understanding of how the Ashe juniper affects groundwater recharge, herbaceous productivity and evapotranspirational water loss. Stable isotopes of hydrogen and oxygen from precipitation, soil water, plant xylem water, and groundwater reveal the current ecosystem hydrology. A comparison of the isotopic compositions of potential water sources and juniper stem water indicates the source water utilized by the Ashe juniper. At the Honey Creek State Natural Area, Comal County, Texas the plant, soil and spring water as representative groundwater were sampled at approximately two month intervals over an annual cycle from two adjacent watersheds and analyzed for hydrogen and oxygen isotope composition. Soils were sampled at depth intervals of 5 to 10 cm and soil water content measured. Mass balance calculations using oxygen isotope data from the dry periods of the year, late summer and winter, indicate the Ashe juniper derives between 72% and 100% of it water from groundwater. In contrast, during the wet periods of the year, spring and fall, mass balance calculations indicate that between 45% and 100% of Ashe juniper's water is derived from soil water. Hydrogen isotope data from a subset of samples are consistent with these results. Bowens ratio measurements of evapotranspiration were

  7. Assessment of paleo-oxygenation conditions on the Agua Nueva Formation (Cenomanian-Turonian), Central Mexico

    NASA Astrophysics Data System (ADS)

    Nuñez, F.; Canet, C.; Barragan-Manzo, R.; Alfonso, P.

    2013-05-01

    Organic-carbon-rich, laminated sediments are characteristic and widespread in the global stratigraphic record of the mid-Cretaceous, mainly during the Oceanic Anoxic Events (OAE's). In central-eastern Mexico, deposits of the Agua Nueva Formation are constituted by dark-gray, carbonaceous and laminated limestone with pyritic layers related to the Cenomanian-Turonian OAE 2. Herein, through different proxies, variations of paleo-redox conditions are studied in detail on a stratigraphic section of the Agua Nueva Formation. A first approach to redox conditions comes from the analysis of the stratigraphic record. Laminated fabrics and the paucity of bioturbation are typical features of a poorly oxygenated sedimentary environment. The presence of well-preserved fish remains and inoceramid bivalve shells is also consistent with those conditions. On the other hand, discrete light-colored and bioturbated thin levels indicate limited increases in the dissolved oxygen content. Geochemical proxies include δ13C in carbonates, δ34S in pyrite and the concentration of various redox-sensitive trace-elements. δ13C (VPDB) ranges from 0.39‰ to 1.30‰, whereas δ34Spy (VCDT) is between -41.23‰ and -11.27‰. The stratigraphic variation patterns of both isotopic values (δ13C and δ34S) are roughly opposite, reflecting changes in the burial of organic matter (OM) and, consequently, in the rate of bacterial sulphate reduction. Thus, positive 13C-rich carbonates represent lower free oxygen condition which enhanced burial flux of OM, tend to shift δ13C of carbonates toward positive values and triggered the incorporation of 32S into the sulfide by bacteria. This situation is also suggested by an enrichment of the sediments in V, Ni, Cr, Cu, Co, Zn, Mo and U. The abundance and size distribution of pyrite framboids proved to be in good agreement with the geochemical results. They also suggest dysoxic to anoxic conditions for the stratigraphic section studied. Both parameters have been

  8. Impact of sensor's point spread function on land cover characterization: Assessment and deconvolution

    USGS Publications Warehouse

    Huang, C.; Townshend, J.R.G.; Liang, S.; Kalluri, S.N.V.; DeFries, R.S.

    2002-01-01

    Measured and modeled point spread functions (PSF) of sensor systems indicate that a significant portion of the recorded signal of each pixel of a satellite image originates from outside the area represented by that pixel. This hinders the ability to derive surface information from satellite images on a per-pixel basis. In this study, the impact of the PSF of the Moderate Resolution Imaging Spectroradiometer (MODIS) 250 m bands was assessed using four images representing different landscapes. Experimental results showed that though differences between pixels derived with and without PSF effects were small on the average, the PSF generally brightened dark objects and darkened bright objects. This impact of the PSF lowered the performance of a support vector machine (SVM) classifier by 5.4% in overall accuracy and increased the overall root mean square error (RMSE) by 2.4% in estimating subpixel percent land cover. An inversion method based on the known PSF model reduced the signals originating from surrounding areas by as much as 53%. This method differs from traditional PSF inversion deconvolution methods in that the PSF was adjusted with lower weighting factors for signals originating from neighboring pixels than those specified by the PSF model. By using this deconvolution method, the lost classification accuracy due to residual impact of PSF effects was reduced to only 1.66% in overall accuracy. The increase in the RMSE of estimated subpixel land cover proportions due to the residual impact of PSF effects was reduced to 0.64%. Spatial aggregation also effectively reduced the errors in estimated land cover proportion images. About 50% of the estimation errors were removed after applying the deconvolution method and aggregating derived proportion images to twice their dimensional pixel size. ?? 2002 Elsevier Science Inc. All rights reserved.

  9. The Promise of mHealth: Daily Activity Monitoring and Outcome Assessments by Wearable Sensors

    PubMed Central

    Dobkin, Bruce H.; Dorsch, Andrew

    2014-01-01

    Mobile health tools that enable clinicians and researchers to monitor the type, quantity, and quality of everyday activities of patients and trial participants have long been needed to improve daily care, design more clinically meaningful randomized trials of interventions, and establish cost-effective, evidence-based practices. Inexpensive, unobtrusive wireless sensors, including accelerometers, gyroscopes, and pressure-sensitive textiles, combined with Internet-based communications and machine-learning algorithms trained to recognize upper- and lower-extremity movements, have begun to fulfill this need. Continuous data from ankle triaxial accelerometers, for example, can be transmitted from the home and community via WiFi or a smartphone to a remote data analysis server. Reports can include the walking speed and duration of every bout of ambulation, spatiotemporal symmetries between the legs, and the type, duration, and energy used during exercise. For daily care, this readily accessible flow of real-world information allows clinicians to monitor the amount and quality of exercise for risk factor management and compliance in the practice of skills. Feedback may motivate better self-management as well as serve home-based rehabilitation efforts. Monitoring patients with chronic diseases and after hospitalization or the start of new medications for a decline in daily activity may help detect medical complications before rehospitalization becomes necessary. For clinical trials, repeated laboratory-quality assessments of key activities in the community, rather than by clinic testing, self-report, and ordinal scales, may reduce the cost and burden of travel, improve recruitment and retention, and capture more reliable, valid, and responsive ratio-scaled outcome measures that are not mere surrogates for changes in daily impairment, disability, and functioning. PMID:21989632

  10. A Multi-Sensor Approach for Satellite Soil Moisture Monitoring for Agricultural Climate Risk Assessment

    NASA Astrophysics Data System (ADS)

    Champagne, C.; Cherneski, P.; Hadwen, T. A.; Davidson, A.

    2014-12-01

    Satellite missions specifically dedicated to soil moisture retrieval have become a reality in the past few years, with the launch of SMOS in 2009 and SMAP in 2014. While much of the work on applications around these missions has focussed on data assimilation systems for numerical weather prediction, there is also potential to use the data to support agricultural applications such as drought and flood assessment and yield forecasting. Previous work has examined the potential for using SMOS soil moisture for detecting spatial and temporal patterns of agroclimate risk, such as drought and excess wetness. This research builds upon that work through the examination of a data set with a longer reference period to determine if the dataset can be used as a baseline for detecting anomalies from normal conditions. Surface satellite soil moisture from a multi-sensor climate reference data set (1993 to 2010) and the SMOS surface soil moisture data (2010 - 2014) set were examined in hindsight to detect relevant trends for monitoring the climate conditions in agricultural regions of Canada. Soil moisture and soil moisture anomalies were examined against precipitation and temperature records over the relevant time periods, and compared against agroclimatic drought risk indicators, including the Palmer Drought Severity Index, the Standardized Precipitation Index and the MODIS Normalized Difference Vegetation Condition anomalies. High impact events, including the 2002 drought in the Canadian Prairies, excess wetness in the southern Manitoba in 2009 and 2011 were evaluated in detail. The potential for using these data sets in near real time to support agricultural decision making will be discussed.

  11. The promise of mHealth: daily activity monitoring and outcome assessments by wearable sensors.

    PubMed

    Dobkin, Bruce H; Dorsch, Andrew

    2011-01-01

    Mobile health tools that enable clinicians and researchers to monitor the type, quantity, and quality of everyday activities of patients and trial participants have long been needed to improve daily care, design more clinically meaningful randomized trials of interventions, and establish cost-effective, evidence-based practices. Inexpensive, unobtrusive wireless sensors, including accelerometers, gyroscopes, and pressure-sensitive textiles, combined with Internet-based communications and machine-learning algorithms trained to recognize upper- and lower-extremity movements, have begun to fulfill this need. Continuous data from ankle triaxial accelerometers, for example, can be transmitted from the home and community via WiFi or a smartphone to a remote data analysis server. Reports can include the walking speed and duration of every bout of ambulation, spatiotemporal symmetries between the legs, and the type, duration, and energy used during exercise. For daily care, this readily accessible flow of real-world information allows clinicians to monitor the amount and quality of exercise for risk factor management and compliance in the practice of skills. Feedback may motivate better self-management as well as serve home-based rehabilitation efforts. Monitoring patients with chronic diseases and after hospitalization or the start of new medications for a decline in daily activity may help detect medical complications before rehospitalization becomes necessary. For clinical trials, repeated laboratory-quality assessments of key activities in the community, rather than by clinic testing, self-report, and ordinal scales, may reduce the cost and burden of travel, improve recruitment and retention, and capture more reliable, valid, and responsive ratio-scaled outcome measures that are not mere surrogates for changes in daily impairment, disability, and functioning. PMID:21989632

  12. Assessing the role of oxygen on ring current formation and evolution through numerical experiments

    NASA Astrophysics Data System (ADS)

    Ilie, R.; Liemohn, M. W.; Toth, G.; Yu Ganushkina, N.; Daldorff, L. K. S.

    2015-06-01

    We address the effect of ionospheric outflow and magnetospheric ion composition on the physical processes that control the development of the 5 August 2011 magnetic storm. Simulations with the Space Weather Modeling Framework are used to investigate the global dynamics and energization of ions throughout the magnetosphere during storm time, with a focus on the formation and evolution of the ring current. Simulations involving multifluid (with variable H+/O+ ratio in the inner magnetosphere) and single-fluid (with constant H+/O+ ratio in the inner magnetosphere) MHD for the global magnetosphere with inner boundary conditions set either by specifying a constant ion density or by physics-based calculations of the ion fluxes reveal that dynamical changes of the ion composition in the inner magnetosphere alter the total energy density of the magnetosphere, leading to variations in the magnetic field as well as particle drifts throughout the simulated domain. A low oxygen to hydrogen ratio and outflow resulting from a constant ion density boundary produced the most disturbed magnetosphere, leading to a stronger ring current but misses the timing of the storm development. Conversely, including a physics-based solution for the ionospheric outflow to the magnetosphere system leads to a reduction in the cross-polar cap potential (CPCP). The increased presence of oxygen in the inner magnetosphere affects the global magnetospheric structure and dynamics and brings the nightside reconnection point closer to the Earth. The combination of reduced CPCP together with the formation of the reconnection line closer to the Earth yields less adiabatic heating in the magnetotail and reduces the amount of energetic plasma that has access to the inner magnetosphere.

  13. Assessing the Relationship between Lung Density and Function with Oxygen-Enhanced Magnetic Resonance Imaging in a Mouse Model of Emphysema

    PubMed Central

    Zurek, Magdalena; Sladen, Louise; Johansson, Edvin; Olsson, Marita; Jackson, Sonya; Zhang, Hui; Mayer, Gaell; Hockings, Paul D.

    2016-01-01

    Purpose A magnetic resonance imaging method is presented that allows for the simultaneous assessment of oxygen delivery, oxygen uptake, and parenchymal density. The technique is applied to a mouse model of porcine pancreatic elastase (PPE) induced lung emphysema in order to investigate how structural changes affect lung function. Method Nine-week-old female C57BL6 mice were instilled with saline or PPE at days 0 and 7. At day 19, oxygen delivery, oxygen uptake, and lung density were quantified from T1 and proton-density measurements obtained via oxygen-enhanced magnetic resonance imaging (OE-MRI) using an ultrashort echo-time imaging sequence. Subsequently, the lungs were sectioned for histological observation. Blood-gas analyses and pulmonary functional tests via FlexiVent were performed in separate cohorts. Principal Findings PPE-challenged mice had reduced density when assessed via MRI, consistent with the parenchyma loss observed in the histology sections, and an increased lung compliance was detected via FlexiVent. The oxygenation levels, as assessed via the blood-gas analysis, showed no difference between PPE-challenged animals and control. This finding was mirrored in the global MRI assessments of oxygen delivery and uptake, where the changes in relaxation time indices were matched between the groups. The heterogeneity of the same parameters however, were increased in PPE-challenged animals. When the oxygenation status was investigated in regions of varying density, a reduced oxygen-uptake was found in low-density regions of PPE-challenged mice. In high-density regions the uptake was higher than that of regions of corresponding density in control animals. The oxygen delivery was proportional to the oxygen uptake in both groups. Conclusions The proposed method allowed for the regional assessment of the relationship between lung density and two aspects of lung function, the oxygen delivery and uptake. When compared to global indices of lung function, an

  14. Assessment and Certification of Neonatal Incubator Sensors through an Inferential Neural Network

    PubMed Central

    de Araújo Júnior, José Medeiros; de Menezes Júnior, José Maria Pires; de Albuquerque, Alberto Alexandre Moura; Almeida, Otacílio da Mota; de Araújo, Fábio Meneghetti Ugulino

    2013-01-01

    Measurement and diagnostic systems based on electronic sensors have been increasingly essential in the standardization of hospital equipment. The technical standard IEC (International Electrotechnical Commission) 60601-2-19 establishes requirements for neonatal incubators and specifies the calibration procedure and validation tests for such devices using sensors systems. This paper proposes a new procedure based on an inferential neural network to evaluate and calibrate a neonatal incubator. The proposal presents significant advantages over the standard calibration process, i.e., the number of sensors is drastically reduced, and it runs with the incubator under operation. Since the sensors used in the new calibration process are already installed in the commercial incubator, no additional hardware is necessary; and the calibration necessity can be diagnosed in real time without the presence of technical professionals in the neonatal intensive care unit (NICU). Experimental tests involving the aforementioned calibration system are carried out in a commercial incubator in order to validate the proposal. PMID:24248278

  15. Assessment and certification of neonatal incubator sensors through an inferential neural network.

    PubMed

    de Araújo, José Medeiros; de Menezes, José Maria Pires; Moura de Albuquerque, Alberto Alexandre; da Mota Almeida, Otacílio; Ugulino de Araújo, Fábio Meneghetti

    2013-01-01

    Measurement and diagnostic systems based on electronic sensors have been increasingly essential in the standardization of hospital equipment. The technical standard IEC (International Electrotechnical Commission) 60601-2-19 establishes requirements for neonatal incubators and specifies the calibration procedure and validation tests for such devices using sensors systems. This paper proposes a new procedure based on an inferential neural network to evaluate and calibrate a neonatal incubator. The proposal presents significant advantages over the standard calibration process, i.e., the number of sensors is drastically reduced, and it runs with the incubator under operation. Since the sensors used in the new calibration process are already installed in the commercial incubator, no additional hardware is necessary; and the calibration necessity can be diagnosed in real time without the presence of technical professionals in the neonatal intensive care unit (NICU). Experimental tests involving the aforementioned calibration system are carried out in a commercial incubator in order to validate the proposal. PMID:24248278

  16. CUMAS: a seafloor multi-sensor module for volcanic hazard monitoring - First long-term experiment and performance assessment

    NASA Astrophysics Data System (ADS)

    Iannaccone, G.; Guardato, S.; Vassallo, M.; Stabile, T. A.; Elia, L.; Beranzoli, L.

    2009-12-01

    A seafloor multi-sensor module with real-time data transmission, named CUMAS (Cabled Underwater Module for Acquisition of Seismological data), has been deployed in January 2008 in the Gulf of Pozzuoli, in the Campi Flegrei caldera (southern Italy), which is one of the most active volcanic areas in the world. The sensors installed in CUMAS were selected to monitor a set of signals related to the local seismicity as well as the ground uplift and subsidence of the seafloor that are related to the bradyseismic phenomenon. In particular, together with a broad-band three-component seismometer and a low-frequency hydrophone, a seafloor water-pressure sensor is used to assess the feasibility of measurements of the slow vertical movement of the seafloor (bradyseism). Further sensors are acquired by two embedded Linux computers, namely tilt and heading sensors for the measure of the actual module orientation on the seafloor, and status sensors that monitor the state of health of the vessel (e.g., internal temperature, power absorption, water intrusion). The underwater acquisition systems are linked to a support infrastructure, a floating buoy (elastic beacon), through an electro-mechanical cable with an Ethernet line. The buoy provides the needed power supply thanks to batteries charged by solar panels and a wind- generator. A Wi-Fi antenna on the buoy is used to transmit the seafloor data from the sea surface to the land acquisition centre in the city of Naples. A meteorological station is also mounted on the buoy, to allow the correlation of the air and seafloor data. CUMAS, although based on commercial sensors, relies on an original system for the centralized management of a wide set of geophysical and physical oceanographic sensors, that handles the continuous data acquisition and real-time data transmission. After the installation in the Gulf of Pozzuoli at about 100 m w.d., and after a test period, CUMAS uninterruptedly operated from May 2008 to June 2009, thus

  17. Chemical sensors

    SciTech Connect

    Janata, J.; Josowicz, M.; DeVaney, D.M. )

    1994-06-15

    This review of chemical sensors contains the following topics of interest: books and reviews; reviews of sensors by their type; fabrication and selectivity; data processing; thermal sensors; mass sensors (fabrication, gas sensors, and liquid sensors); electrochemical sensors (potentiometric sensors, amperometric sensors, and conductometric sensors); and optical sensors (fabrication, liquid sensors, biosensors, and gas sensors). 795 refs., 1 tab.

  18. Assessing the Performance of Sensor Fusion Methods: Application to Magnetic-Inertial-Based Human Body Tracking

    PubMed Central

    Ligorio, Gabriele; Bergamini, Elena; Pasciuto, Ilaria; Vannozzi, Giuseppe; Cappozzo, Aurelio; Sabatini, Angelo Maria

    2016-01-01

    Information from complementary and redundant sensors are often combined within sensor fusion algorithms to obtain a single accurate observation of the system at hand. However, measurements from each sensor are characterized by uncertainties. When multiple data are fused, it is often unclear how all these uncertainties interact and influence the overall performance of the sensor fusion algorithm. To address this issue, a benchmarking procedure is presented, where simulated and real data are combined in different scenarios in order to quantify how each sensor’s uncertainties influence the accuracy of the final result. The proposed procedure was applied to the estimation of the pelvis orientation using a waist-worn magnetic-inertial measurement unit. Ground-truth data were obtained from a stereophotogrammetric system and used to obtain simulated data. Two Kalman-based sensor fusion algorithms were submitted to the proposed benchmarking procedure. For the considered application, gyroscope uncertainties proved to be the main error source in orientation estimation accuracy for both tested algorithms. Moreover, although different performances were obtained using simulated data, these differences became negligible when real data were considered. The outcome of this evaluation may be useful both to improve the design of new sensor fusion methods and to drive the algorithm tuning process. PMID:26821027

  19. Acute toxicity assessment of N,N-diethyl-m-toluamide (DEET) on the oxygen flux of the dinoflagellate Gymnodinium instriatum.

    PubMed

    Martinez, Eloy; Vélez, Sylvia M; Mayo, Marietta; Sastre, Miguel P

    2016-01-01

    Despite the ubiquitous occurrence of N,N-diethyl-m-toluamide (DEET) in aquatic systems, assessments evaluating the toxicity of DEET on phytoplankton species are summed to a single study on a unicellular green alga. In particular, the toxicological effects of DEET in dinoflagellates are unknown. In this study, we employed the mixotrophic dinoflagellate Gymnodinium instriatum as a study system to evaluate acute effects of DEET on the oxygen flux of laboratory cultures. This study reports an inhibitory reaction model of DEET described by the equation y = 4.99x(0.54), where y represents the percent inhibition of oxygen flux and x represents DEET concentration in mg L(−1) (r(2) = 0.98). Based on this model, the effective concentration of DEET needed to reduce O2 flux by 50% (EC50) for this species was found to be at 72.9 mg L(−1). The reported EC50 is more than five times lower than the EC50 reported previously for the unicellular green algae Chlorella protothecoides. This study raises the question of the potential toxicological effects of DEET in dinoflagellates, in particular those populations inhabiting systems characterized by low water circulation such as enclosed bays and lagoons. PMID:26467804

  20. Removal and fate of endocrine disruptors chemicals under lab-scale postreatment stage. Removal assessment using light, oxygen and microalgae.

    PubMed

    Abargues, M R; Ferrer, J; Bouzas, A; Seco, A

    2013-12-01

    The aim of this study was to assess the effect of light, oxygen and microalgae on micropollutants removal. The studied micropollutants were 4-(1,1,3,3-tetramethylbutyl)phenol (OP), technical-nonylphenol (t-NP), 4-n-nonylphenol (4-NP), Bisphenol-A (BPA). In order to study the effect of the three variables on the micropollutants removal, a factorial design was developed. The experiments were carried out in four batch reactors which treated the effluent of an anaerobic membrane bioreactor. The gas chromatography mass spectrometry was used for the measurement of the micropollutants. The results showed that light, oxygen and microalgae affected differently to the degradation ratios of each micropollutant. The results showed that under aerated conditions removal ratios higher than 91% were achieved, whereas for non-aerated conditions the removal ratios were between 50% and 80%, except for 4-NP which achieved removal ratios close to 100%. Besides, mass balance showed that the degradation processes were more important than the sorption processes. PMID:24096281

  1. Assessment of oxygen and carbogen therapy effect in Meniere's disease according to clinical and electroencephalographic data

    NASA Technical Reports Server (NTRS)

    Boronoyev, A. B.

    1980-01-01

    The method of constructing fields on the basis of EEG data gives a quantitative characterization of bioelectrical activity. Fields of average rates of the change of potentials in healthy people have a well defined configuration, where the greatest rates are found in the occipital zones, lower in the frontal and parietal, and least in the temporal zones. In response to functional loads the form of the field remains the same because of a synchronous change in the average rates in both hemispheres of the cerebrum to the same extent. The configuration of the fields of background bioelectric activity of the cerebrum in people with Meniere's disease is not uniform. On the basis of this investigation, a clear correlation was found between the subjective sensations of patients during oxygen and carbogen therapy and the changes in the spatial characteristics of the field of potentials of the cerebrum. This correlation makes it possible to objectively identify the nature of the vascular disturbances in Meniere's disease, develop a pathogenetic treatment plan, and evaluate its effectiveness.

  2. High-sensitivity extended-gate field-effect transistors as pH sensors with oxygen-modified reduced graphene oxide films coated on different reverse-pyramid silicon structures as sensing heads

    NASA Astrophysics Data System (ADS)

    Li, Yu-Ren; Chang, Shih-hsueh; Chang, Chia-Tsung; Tsai, Wan-Lin; Chiu, Yu-Kai; Yang, Po-Yu; Cheng, Huang-Chung

    2016-04-01

    A high-performance extended-gate field-effect transistor (EGFET) as pH sensor with its microstructured sensing head composed of an oxygen-modified reduced graphene oxide film (RGOF) on a reverse-pyramid (RP) Si structure was developed to achieve a high sensitivity of 57.5 mV/pH with an excellent linearity of 0.9929 in a wide pH sensing range of 1-13. These features were ascribed to the large amount of sensing sites and large sensing area. In contrast, the planar Si substrate with the oxygen-plasma-treated RGOF (OPT-RGOF) at the optimal bias power showed a sensitivity of 52.9 mV/pH compared with 45.0 mV/pH for that without plasma treatment. It reveals that oxygen plasma can produce oxygen-containing groups as sensing sites, enhancing proton sensing characteristics. However, oxygen plasma treatment at high bias powers would cause damage to the RGOFs, resulting in poor conducting and sensing properties. On the other hand, the use of the RP structures could increase the effective sensing area and further promote the sensing performance.

  3. Probing the in vivo changes in oxygen saturation with photoacoustic imaging as a non-invasive means of assessing treatment progression

    NASA Astrophysics Data System (ADS)

    Hysi, Eno; May, Jonathan P.; Wirtzfeld, Lauren; Undzys, Elijus; Li, Shyh-Dar; Kolios, Michael C.

    2015-03-01

    In vivo photoacoustic estimations of tumor oxygenation were used to assess the therapeutic efficacy of a thermosensitive liposome treatment in a pre-clinical mouse model. The treated group (n = 12) was administered doxorubicin-loaded, heat sensitive liposomes and exposed to mild hyperthermia (43°C) in order to deliver doxorubicin locally within the tumor micro-vessels. Control groups received systemic doxorubicin (n = 7) or saline (n = 12). The changes in tumor blood vessels after treatment were probed by analyzing the frequency content of the photoacoustic radiofrequency signals. Tumor oxygenation dropped by 15-20% during the first 30 minutes post-treatment when the tumors were exposed to encapsulated (Heat-Activated cyToxic - HaT-DOX) or free doxorubicin (DOX). The early (30 minutes to 5 hours) decrease in oxygen saturation strongly correlated to the reduction in tumor size assessed by caliper measurements. Control animals did not exhibit significant changes in tumor oxygenation at the early time points. The oxygenation at 7 days increased significantly for all groups. Measurements of the spectral slope from the normalized power spectra of the photoacoustic signals could also be used to differentiate between responder and non-responder mice. The results of this study suggest that photoacoustic imaging of tumors undergoing vascular-targeted cancer therapy can be used to assess treatment response early (hours) post-treatment through a combined analysis of oxygen saturation and photoacoustic radiofrequency spectroscopy.

  4. Differences between the Vastus Lateralis and Gastrocnemius Lateralis in the Assessment Ability of Breakpoints of Muscle Oxygenation for Aerobic Capacity Indices During an Incremental Cycling Exercise

    PubMed Central

    Wang, Bangde; Xu, Guodong; Tian, Qingping; Sun, Jinyan; Sun, Bailei; Zhang, Lei; Luo, Qingming; Gong, Hui

    2012-01-01

    In recent years, breakpoints (Bp) of muscle oxygenation have been measured in local muscles using near infrared spectroscopy (NIRS) to assess (predict) systemic aerobic capacity indices [lactate threshold (LT), gas exchange threshold (GET) and maximal oxygen uptake (VO2peak)]. We investigated muscular differences in the assessment (predictive) ability of the Bp of muscle oxygenation for aerobic capacity indices during incremental cycling exercise on the aerobic capacity indices. Thirty-one active college students were recruited for an incremental cycling exercise test, during which NIRS muscle oxygenation in the vastus lateralis (VL) and gastrocnemius lateralis (GL), blood lactate concentration and cardiopulmonary variables were measured simultaneously in a multi-modality approach. A linear regression model was used to analyse the relationship between the Bp of the muscle oxygenation index (OI) and the systemic aerobic capacity indices. The Bp of the muscle OI in both the VL (BpVL) and GL (BpGL) were significantly correlated with the aerobic capacity indices. Additionally, the BpVL had a better goodness-of-fit [higher coefficient of determination (R2, p < 0.001) and lower root mean squared error (RMSE, p < 0.03)] in the linear regressions and occurred earlier than the BpGL. In conclusion, both the BpVL and the BpGL could be measured by NIRS to assess the systemic aerobic capacity indices; however, there were muscular differences in the assessment ability of the Bp of muscle oxygenation. Key points The breakpoints (Bp) of muscle oxygenation index in both vastus lateralis (VL) and gastrocnemius lateralis (GL) could be detected to indicate the breaking up of the oxygen supply-consumption balance by NIRS. The Bp of muscle oxygenation index in both VL (BpVL) and GL (BpGL) were significantly correlated with the systemic aerobic capacity indices. The BpVL owned higher assessment (predictive) ability when the Bp (BpVL and BpGL) of muscle oxygenation index was used to

  5. Assessment of fiber optic sensors and other advanced sensing technologies for nuclear power plants

    SciTech Connect

    Hashemian, H.M.

    1996-03-01

    As a result of problems such as calibration drift in nuclear plant pressure sensors and the recent oil loss syndrome in some models of Rosemount pressure transmitters, the nuclear industry has become interested in fiber optic pressure sensors. Fiber optic sensing technologies have been considered for the development of advanced instrumentation and control (I&C) systems for the next generation of reactors and in older plants which are retrofitted with new I&C systems. This paper presents the results of a six-month Phase I study to establish the state-of-the-art in fiber optic pressure sensing. This study involved a literature review, contact with experts in the field, an industrial survey, a site visit to a fiber optic sensor manufacturer, and laboratory testing of a fiber optic pressure sensor. The laboratory work involved both static and dynamic performance tests. This initial Phase I study has recently been granted a two-year extension by the U.S. Nuclear Regulatory Commission (NRC). The next phase will evaluate fiber optic pressure sensors in specific nuclear plant applications in addition to other advanced methods for monitoring critical nuclear plant equipment.

  6. Smart wearable body sensors for patient self-assessment and monitoring

    PubMed Central

    2014-01-01

    Background Innovations in mobile and electronic healthcare are revolutionizing the involvement of both doctors and patients in the modern healthcare system by extending the capabilities of physiological monitoring devices. Despite significant progress within the monitoring device industry, the widespread integration of this technology into medical practice remains limited. The purpose of this review is to summarize the developments and clinical utility of smart wearable body sensors. Methods We reviewed the literature for connected device, sensor, trackers, telemonitoring, wireless technology and real time home tracking devices and their application for clinicians. Results Smart wearable sensors are effective and reliable for preventative methods in many different facets of medicine such as, cardiopulmonary, vascular, endocrine, neurological function and rehabilitation medicine. These sensors have also been shown to be accurate and useful for perioperative monitoring and rehabilitation medicine. Conclusion Although these devices have been shown to be accurate and have clinical utility, they continue to be underutilized in the healthcare industry. Incorporating smart wearable sensors into routine care of patients could augment physician-patient relationships, increase the autonomy and involvement of patients in regards to their healthcare and will provide for novel remote monitoring techniques which will revolutionize healthcare management and spending. PMID:25232478

  7. Assessment of J1 VIIRS Polarization Sensitivity Impacts on Sensor Data Records

    NASA Astrophysics Data System (ADS)

    Wang, W.; Cao, C.; Pearlman, A.

    2014-12-01

    Prelaunch polarization characterization indicates that the polarization sensitivity in bands M1-M4 of the Visible and Infrared Imaging Radiometer Suite (VIIRS) onboard the Joint Polar Satellite System-1 (JPSS-1, J1) is higher than the performance specifications. It is important to understand its impacts on the sensor data records (SDR) for reliable environment data records retrieval. This study focuses on assessments of the impacts of J1 VIIRS polarization sensitivity on bands M1-M4 SDRs, especially M1, (0.411μm) in which degree of linear polarization (DoLP) due to Rayleigh scattering and instrument polarization sensitivity are more profound than other bands. In this study, we adopts a MODIS polarization correction method proposed by Meister et al. (2005) for J1 VIIRS. Polarization impact (in percent) is defined as (Im-It)/It*100, where Im is J1 measured top of atmosphere (TOA) reflectance and Itis the true TOA reflectance measured by an ideal instrument without polarization sensitivity. J1 VIIRS was assumed to have the same along track and along scan patterns and local equator crossing time as that of the Suomi NPP VIIRS. Clear-sky Stokes vectors for the Rayleigh component were simulated using the Second Simulation of a Satellite Signal in the Solar Spectrum Vector Code, version 1 (6SV) for representative NPP VIIRS orbits over the Pacific Ocean. J1 VIIRS prelaunch polarization sensitivity data, including polarization amplitude and phase angle for each band, HAM-side, detector, and scan angle, were obtained from the NASA VIIRS Calibration Support Team. Figure 1 shows band M1 DoLP derived from 6SV simulated Stokes vectors for a NPP VIIRS orbit over the Pacific Ocean on April 17, 2014 and the impacts of J1 polarization sensitivity on TOA reflectance for the granule over the MOBY site. The impact on band M1 TOA reflectance can be as large as ~4% at the end of scans (western side of the bottom right image), where DoLP reaches ~70% and the J1 polarization amplitude is

  8. Health assessment of gasoline and fuel oxygenate vapors: developmental toxicity in rats.

    PubMed

    Roberts, Linda G; Gray, Thomas M; Trimmer, Gary W; Parker, Robert M; Murray, F Jay; Schreiner, Ceinwen A; Clark, Charles R

    2014-11-01

    Gasoline-vapor condensate (BGVC) or condensed vapors from gasoline blended with methyl t-butyl ether (G/MTBE), ethyl t-butyl ether (G/ETBE), t-amyl methyl ether (G/TAME) diisopropyl ether (G/DIPE), ethanol (G/EtOH), or t-butyl alcohol (G/TBA) were evaluated for developmental toxicity in Sprague-Dawley rats exposed via inhalation on gestation days (GD) 5-20 for 6h/day at levels of 0 (control filtered air), 2000, 10,000, and 20,000mg/m(3). These exposure durations and levels substantially exceed typical consumer exposure during refueling (<1-7mg/m(3), 5min). Dose responsive maternal effects were reduced maternal body weight and/or weight change, and/or reduced food consumption. No significant malformations were seen in any study. Developmental effects occurred at 20,000mg/m(3) of G/TAME (reduced fetal body weight, increased incidence of stunted fetuses), G/TBA (reduced fetal body weight, increased skeletal variants) and G/DIPE (reduced fetal weight) resulting in developmental NOAEL of 10,000mg/m(3) for these materials. Developmental NOAELs for other materials were 20,000mg/m(3) as no developmental toxicity was induced in those studies. Developmental NOAELs were equal to or greater than the concurrent maternal NOAELs which ranged from 2000 to 20,000mg/m(3). There were no clear cut differences in developmental toxicity between vapors of gasoline and gasoline blended with the ether or alcohol oxygenates. PMID:24845242

  9. An assessment of oxygen transfer efficiency in a gas permeable hollow fibre membrane biological reactor.

    PubMed

    Soreanu, G; Lishman, L; Dunlop, S; Behmann, H; Seto, P

    2010-01-01

    The clean water oxygen transfer efficiency (OTE) of a full scale non-porous hollow fibre gas permeable (GP) membrane (surface area of 500 m(2)) was evaluated at inlet air pressures of 1.2, 1.4, and 1.8 atm using two established testing methods. To form a basis of comparison with traditional aeration technologies, additional testing was done with conventional aerators (fine bubble and coarse bubble diffusers) replacing the GP membrane. OTE can be established based on the re-aeration of deoxygenated water or by monitoring the catalytic oxidation of a sodium sulphite (Na(2)SO(3)) solution. In this study, OTE values determined by sulphite oxidation (SOTE(S)) were consistently higher than those established during re-aeration (SOTE(R)) suggesting that the chemical reaction was enhancing the mass transfer. The chemical reaction was sufficiently fast in the case of the GP membrane, that the gas phase limited the mass transfer. The GP membrane operating at 1.2 atm had a SOTE(S) of 70.6% and a SOTER of 52.2%. SOTE(R) for the coarse bubble and fine bubble diffusers were 3.8% and 23.6%, respectively. This is comparable to the manufacturer's values, corrected for depth of 3.4% and 18.3%, respectively. Particularly, the derived OTE values were used to evaluate differences in energy consumption for a conventional treatment plant achieving carbon removal and nitrification. This analysis highlights the potential energy efficiency of GP membranes, which could be considered for the design of the membrane modules. PMID:20220238

  10. Oxygen detection using evanescent fields

    DOEpatents

    Duan, Yixiang; Cao, Weenqing

    2007-08-28

    An apparatus and method for the detection of oxygen using optical fiber based evanescent light absorption. Methylene blue was immobilized using a sol-gel process on a portion of the exterior surface of an optical fiber for which the cladding has been removed, thereby forming an optical oxygen sensor. When light is directed through the optical fiber, transmitted light intensity varies as a result of changes in the absorption of evanescent light by the methylene blue in response to the oxygen concentration to which the sensor is exposed. The sensor was found to have a linear response to oxygen concentration on a semi-logarithmic scale within the oxygen concentration range between 0.6% and 20.9%, a response time and a recovery time of about 3 s, ant to exhibit good reversibility and repeatability. An increase in temperature from 21.degree. C. to 35.degree. C. does not affect the net absorption of the sensor.

  11. An assessment of a 360-degree profiling sensor for object classification

    NASA Astrophysics Data System (ADS)

    Brown, Jeremy B.; Chari, Srikant K.; Jacobs, Eddie L.

    2011-06-01

    Profiling sensor systems have been shown to be effective for detecting and classifying humans against animals. A profiling sensor with a 360 horizontal field of view was used to generate profiles of humans and animals for classification. The sensor system contains a long wave infrared camera focused on a smooth conical mirror to provide a 360 degree field of view. Human and animal targets were detected at 30 meters and an approximate height to width ratio was extracted for each target. Targets were tracked for multiple frames in order to segment targets from background. The average height to width ratio was used as a single feature for classification. The Mahalanobis distance was calculated for each target in the single feature space to provide classification results.

  12. A Nanoparticle-based Sensor Platform for Cell Tracking and Status/Function Assessment.

    PubMed

    Yeo, David; Wiraja, Christian; Chuah, Yon Jin; Gao, Yu; Xu, Chenjie

    2015-01-01

    Nanoparticles are increasingly popular choices for labeling and tracking cells in biomedical applications such as cell therapy. However, all current types of nanoparticles fail to provide real-time, noninvasive monitoring of cell status and functions while often generating false positive signals. Herein, a nanosensor platform to track the real-time expression of specific biomarkers that correlate with cell status and functions is reported. Nanosensors are synthesized by encapsulating various sensor molecules within biodegradable polymeric nanoparticles. Upon intracellular entry, nanosensors reside within the cell cytoplasm, serving as a depot to continuously release sensor molecules for up to 30 days. In the absence of the target biomarkers, the released sensor molecules remain 'Off'. When the biomarker(s) is expressed, a detectable signal is generated (On). As a proof-of-concept, three nanosensor formulations were synthesized to monitor cell viability, secretion of nitric oxide, and β-actin mRNA expression. PMID:26440504

  13. A Nanoparticle-based Sensor Platform for Cell Tracking and Status/Function Assessment

    PubMed Central

    Yeo, David; Wiraja, Christian; Chuah, Yon Jin; Gao, Yu; Xu, Chenjie

    2015-01-01

    Nanoparticles are increasingly popular choices for labeling and tracking cells in biomedical applications such as cell therapy. However, all current types of nanoparticles fail to provide real-time, noninvasive monitoring of cell status and functions while often generating false positive signals. Herein, a nanosensor platform to track the real-time expression of specific biomarkers that correlate with cell status and functions is reported. Nanosensors are synthesized by encapsulating various sensor molecules within biodegradable polymeric nanoparticles. Upon intracellular entry, nanosensors reside within the cell cytoplasm, serving as a depot to continuously release sensor molecules for up to 30 days. In the absence of the target biomarkers, the released sensor molecules remain ‘Off’. When the biomarker(s) is expressed, a detectable signal is generated (On). As a proof-of-concept, three nanosensor formulations were synthesized to monitor cell viability, secretion of nitric oxide, and β-actin mRNA expression. PMID:26440504

  14. The Global Seismographic Network: New Sensor Developments, Quality Assessments and Continuing Challenges

    NASA Astrophysics Data System (ADS)

    Hafner, K.; Davis, J. P.; Wilson, D.; Woodward, R.

    2015-12-01

    The Global Seismographic Network (GSN) is a 151 station, globally distributed permanent network of state-of-the-art seismological and geophysical sensors that is a result of an ongoing successful partnership between IRIS, the USGS, the University of California at San Diego, NSF and numerous host institutions worldwide. In recent years, the GSN has standardized their dataloggers to the Quanterra Q330HR data acquisition system at all but three stations. Current equipment modernization efforts are focused on the development of a new very broadband borehole sensor to replace failing KS-54000 instruments and replacing the aging Streckeisen STS-1 surface instruments at many GSN stations. Aging of GSN equipment and discoveries of quality problems with GSN data (e.g., the long period response of the STS-1 sensors) have resulted in the GSN placing major emphasis on quantifying, validating and maintaining data quality. This has resulted in the implementation of MUSTANG and DQA systems for analyzing GSN data quality and enables both network operators and data end users to quickly characterize the performance of stations and networks. We will present summary data quality metrics for the GSN as obtained via these quality assurance tools. Data from the GSN are used not only for research, but on a daily basis are part of the operational missions of the USGS NEIC, NOAA tsunami warning centers, the Comprehensive Nuclear-Test-Ban-Treaty Organization as well as other organizations. The primary challenges for the GSN include maintaining these operational capabilities while simultaneously developing and replacing the primary borehole sensors, replacing as needed the primary vault sensors, maintaining high quality data and repairing station infrastructure, all during a period of very tight federal budgets. We will provide an overview of the operational status of the GSN, with a particular emphasis on the status of the primary borehole and vault sensors.

  15. Assessment, Validation, and Refinement of the Atmospheric Correction Algorithm for the Ocean Color Sensors. Chapter 19

    NASA Technical Reports Server (NTRS)

    Wang, Menghua

    2003-01-01

    The primary focus of this proposed research is for the atmospheric correction algorithm evaluation and development and satellite sensor calibration and characterization. It is well known that the atmospheric correction, which removes more than 90% of sensor-measured signals contributed from atmosphere in the visible, is the key procedure in the ocean color remote sensing (Gordon and Wang, 1994). The accuracy and effectiveness of the atmospheric correction directly affect the remotely retrieved ocean bio-optical products. On the other hand, for ocean color remote sensing, in order to obtain the required accuracy in the derived water-leaving signals from satellite measurements, an on-orbit vicarious calibration of the whole system, i.e., sensor and algorithms, is necessary. In addition, it is important to address issues of (i) cross-calibration of two or more sensors and (ii) in-orbit vicarious calibration of the sensor-atmosphere system. The goal of these researches is to develop methods for meaningful comparison and possible merging of data products from multiple ocean color missions. In the past year, much efforts have been on (a) understanding and correcting the artifacts appeared in the SeaWiFS-derived ocean and atmospheric produces; (b) developing an efficient method in generating the SeaWiFS aerosol lookup tables, (c) evaluating the effects of calibration error in the near-infrared (NIR) band to the atmospheric correction of the ocean color remote sensors, (d) comparing the aerosol correction algorithm using the singlescattering epsilon (the current SeaWiFS algorithm) vs. the multiple-scattering epsilon method, and (e) continuing on activities for the International Ocean-Color Coordinating Group (IOCCG) atmospheric correction working group. In this report, I will briefly present and discuss these and some other research activities.

  16. DEVELOPMENT OF SELF-TUNING RESIDENTIAL OIL/BURNER - OXYGEN SENSOR ASSESSMENT AND EARLY PROTOTYPE SYSTEM OPERATING EXPERIENCE

    SciTech Connect

    MCDONALD,R.J.; BUTCHER,T.A.; KRAJEWSKI,R.F.

    1998-09-01

    This document is the first topical report dealing with a new project leading towards the development of a self-tuning residential oil burner. It was initiated under the Statement of Work for the Oil Heat Research and Development Program, for Fiscal Year 1997 as defined in the Combustion Equipment Technology Program, under the management of Brookhaven National Laboratory (BNL). In part, this work is based on research reported by BNL in 1990, suggesting various options for developing control strategies in oil heat technology leading to the enhanced efficiency of oil-fired heating systems. BNL has been addressing these concepts in order of priority and technology readiness. The research described in this report is part of an ongoing project and additional work is planned for the future assuming adequate program funding is made available.

  17. A New Sensor for the Assessment of Personal Exposure to Volatile Organic Compounds

    PubMed Central

    Chen, Cheng; Campbell, Katherine Driggs; Negi, Indira; Iglesias, Rodrigo A.; Owens, Patrick; Tao, Nongjian; Tsow, Francis; Forzani, Erica

    2012-01-01

    To improve our understanding of indoor and outdoor personal exposures to common environmental toxicants released into the environment, new technologies that can monitor and quantify the toxicants anytime anywhere are needed. This paper presents a wearable sensor to provide such capabilities. The sensor can communicate with a common smart phone and provides accurate measurement of volatile organic compound concentration at a personal level in real time, providing environmental toxicants data every three minutes. The sensor has high specificity and sensitivity to aromatic, alkyl, and chlorinated hydrocarbons with a resolution as low as 4 parts per billion (ppb), with a detection range of 4 ppb to 1000 ppm (parts per million). The sensor's performance was validated using Gas Chromatography and Selected Ion Flow Tube - Mass Spectrometry reference methods in a variety of environments and activities with overall accuracy higher than 81% (r2 > 0.9). Field tests examined personal exposure in various scenarios including: indoor and outdoor environments, traffic exposure in different cities which vary from 0 to 50 ppmC (part-per-million carbon from hydrocarbons), and pollutants near the 2010 Deepwater Horizon's oil spill. These field tests not only validated the performance but also demonstrated unprecedented high temporal and spatial toxicant information provided by the new technology. PMID:22736952

  18. Assessment of the short-term radiometric stability between Terra MODIS and Landsat 7 ETM+ sensors

    USGS Publications Warehouse

    Choi, Taeyoung; Xiong, Xiaoxiong; Chander, Gyanesh; Angal, A.

    2009-01-01

    Short-term radiometric stability was evaluated using continuous ETM+ scenes within a single orbit (contact period) and the corresponding MODIS scenes for the four matching solar reflective visible and near-infrared (VNIR) band pairs between the two sensors. The near-simultaneous earth observations were limited by the smaller swath size of ETM+ (183 km) compared to MODIS (2330 km). Two sets of continuous granules for Terra MODIS and Landsat 7 ETM+ were selected and mosaicked based on pixel geolocation information for noncloudy pixels over the African continent. The matching pixel pairs were resampled from a fine to a coarse pixel resolution, and the at-sensor spectral radiance values for a wide dynamic range of the sensors were compared and analyzed, covering various surface types. The following study focuses on radiometric stability analysis from the VNIR band-pairs of ETM+ and MODIS. The Libya-4 desert target was included in the path of this continuous orbit, which served as a verification point between the short-term and the long-term trending results from previous studies. MODTRAN at-sensor spectral radiance simulation is included for a representative desert surface type to evaluate the consistency of the results.

  19. Initial assessments of life support technology evolution and advanced sensor requirements, volume 2, appendix A

    NASA Technical Reports Server (NTRS)

    Montgomery, Edward E.

    1991-01-01

    The primary issues studied were how the transition from a physical/chemical (P/C) to hybrid to a Closed Ecological Life Support System (CELSS) could be achieved, what sensors and monitors are needed for a P/C -CELSS hybrid system, and how a CELSS could be automated and what controls would be needed to do so.

  20. SOIL QUALITY OF CLAYPAN SOILS ASSESSED USING SENSOR BASED SOIL EC AND TERRAIN ATTRIBUTES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil quality is a concept of quantifying characteristics of the soil relative to various soil function, but in practice it is used very little because of time and cost constraints. Our objectives with this research were to (1)identify whether sensor-based soil EC and terrain attribute information ca...

  1. Assessment of Rifle Marksmanship Skill Using Sensor-Based Measures. CRESST Report 755

    ERIC Educational Resources Information Center

    Nagashima, Sam O.; Chung, Gregory K. W. K.; Espinosa, Paul D.; Berka, Chris; Baker, Eva L.

    2009-01-01

    The goal of this report was to test the use of sensor-based skill measures in evaluating performance differences in rifle marksmanship. Ten shots were collected from 30 novices and 9 experts. Three measures for breath control and one for trigger control were used to predict skill classification. The data were fitted with a logistic regression…

  2. New method for assessment of gait variability based on wearable ground reaction force sensor.

    PubMed

    Liu, Tao; Inoue, Yoshio; Shibata, Kyoko

    2008-01-01

    In this paper, a new quantitative method of analyzing gait variability using a developed wearable ground reaction force (GRF) sensor system is presented. The design of the sensor system is based on the use of five small 3-axial sensors distributed on the underside of a shoe, so that in human dynamics analysis this system can continuously measure vertical pressure force and bio-directional friction forces referring to anterior-posterior friction force and mediolateral friction force. Compared to existing spatio-temporal evaluation methods using traditional force plates or instrumented treadmills, the new method was developed based on measurements of ambulatory or wearable force sensor which can continuously measure ground reaction force in various environments not limited to the laboratory environment. The area of the center of pressure (CoP) distribution on the foot-plate and the average coefficient of variation of the 3-axial GRF, which correlate strongly with the distribution of CoP, are suggested parameters for quantifying gait variability. To certify the effectiveness of these parameters, we conducted an experimental study on a group of volunteer subjects who walked under a designed experimental protocol. PMID:19163171

  3. A new sensor for the assessment of personal exposure to volatile organic compounds

    NASA Astrophysics Data System (ADS)

    Chen, Cheng; Driggs Campbell, Katherine; Negi, Indira; Iglesias, Rodrigo A.; Owens, Patrick; Tao, Nongjian; Tsow, Francis; Forzani, Erica S.

    2012-07-01

    To improve our understanding of indoor and outdoor personal exposures to common environmental toxicants released into the environment, new technologies that can monitor and quantify the toxicants anytime anywhere are needed. This paper presents a wearable sensor to provide such capabilities. The sensor can communicate with a common smart phone and provides accurate measurement of volatile organic compound concentration at a personal level in real-time, providing environmental toxicants data every three minutes. The sensor has high specificity and sensitivity to aromatic, alkyl, and chlorinated hydrocarbons with a resolution as low as 4 parts-per-billion (ppb), with a detection range of 4 ppb-1000 ppm (parts-per-million). The sensor's performance was validated using Gas Chromatography and Selected Ion Flow Tube - Mass Spectrometry reference methods in a variety of environments and activities with overall accuracy higher than 81% (r2 > 0.9). Field tests examined personal exposure in various scenarios including: indoor and outdoor environments, traffic exposure in different cities which vary from 0 to 50 ppmC (part-per-million carbon from hydrocarbons), and pollutants near the 2010 Deepwater Horizon's oil spill. These field tests not only validated the performance but also demonstrated unprecedented high temporal and spatial toxicant information provided by the new technology.

  4. A New Sensor for the Assessment of Personal Exposure to Volatile Organic Compounds.

    PubMed

    Chen, Cheng; Campbell, Katherine Driggs; Negi, Indira; Iglesias, Rodrigo A; Owens, Patrick; Tao, Nongjian; Tsow, Francis; Forzani, Erica

    2012-07-01

    To improve our understanding of indoor and outdoor personal exposures to common environmental toxicants released into the environment, new technologies that can monitor and quantify the toxicants anytime anywhere are needed. This paper presents a wearable sensor to provide such capabilities. The sensor can communicate with a common smart phone and provides accurate measurement of volatile organic compound concentration at a personal level in real time, providing environmental toxicants data every three minutes. The sensor has high specificity and sensitivity to aromatic, alkyl, and chlorinated hydrocarbons with a resolution as low as 4 parts per billion (ppb), with a detection range of 4 ppb to 1000 ppm (parts per million). The sensor's performance was validated using Gas Chromatography and Selected Ion Flow Tube - Mass Spectrometry reference methods in a variety of environments and activities with overall accuracy higher than 81% (r(2) > 0.9). Field tests examined personal exposure in various scenarios including: indoor and outdoor environments, traffic exposure in different cities which vary from 0 to 50 ppmC (part-per-million carbon from hydrocarbons), and pollutants near the 2010 Deepwater Horizon's oil spill. These field tests not only validated the performance but also demonstrated unprecedented high temporal and spatial toxicant information provided by the new technology. PMID:22736952

  5. Performance modeling and assessment of infrared-sensors applicable for TALOS project UGV as a function of target/background and environmental conditions

    NASA Astrophysics Data System (ADS)

    Barbe, Stephane; Krapez, Jean-Claude; Louvet, Yolande

    2012-06-01

    TALOS (Transportable and Autonomous Land bOrder Surveillance system - www.talos-border.eu) is an international research project co-funded from EU 7th Framework Program funds in Security priority. The main objective of TALOS project is to develop and field test the innovative concept of a mobile, autonomous system for protecting European land borders. Unmanned Ground Vehicles (UGVs) are major components of TALOS project. The UGVs will be equipped with long range radar for detection of moving vehicle and people, as well as long focal length EO/IR sensors allowing the operator to recognize and identify the detected objects of interest. Furthermore medium focal length IR sensors are used to allow the operator to drive the UGV. Those sensors must fulfill mission requirements for extremely various environmental conditions (backgrounds, topographic characteristics, climatic conditions, weather conditions) existing from Finland in the North and Bulgaria / Turkey in the South of Europe. An infrared sensor performance model was developed at ONERA in order to evaluate target detection, recognition and identification range for several simulations cases representative of the whole environmental variability domain. Results analysis allows assessing the operability domain of the infrared sensors. This paper presents the infrared sensor performance evaluation methodology and the synthesis of a large number of simulation results applied to two infrared sensors of interest: a medium / long range cooled MWIR sensor for observation and a short / medium uncooled LWIR sensor for navigation.

  6. Implementation of a multi-modal mobile sensor system for surface and subsurface assessment of roadways

    NASA Astrophysics Data System (ADS)

    Wang, Ming; Birken, Ralf; Shahini Shamsabadi, Salar

    2015-03-01

    There are more than 4 million miles of roads and 600,000 bridges in the United States alone. On-going investments are required to maintain the physical and operational quality of these assets to ensure public's safety and prosperity of the economy. Planning efficient maintenance and repair (M&R) operations must be armed with a meticulous pavement inspection method that is non-disruptive, is affordable and requires minimum manual effort. The Versatile Onboard Traffic Embedded Roaming Sensors (VOTERS) project developed a technology able to cost- effectively monitor the condition of roadway systems to plan for the right repairs, in the right place, at the right time. VOTERS technology consists of an affordable, lightweight package of multi-modal sensor systems including acoustic, optical, electromagnetic, and GPS sensors. Vehicles outfitted with this technology would be capable of collecting information on a variety of pavement-related characteristics at both surface and subsurface levels as they are driven. By correlating the sensors' outputs with the positioning data collected in tight time synchronization, a GIS-based control center attaches a spatial component to all the sensors' measurements and delivers multiple ratings of the pavement every meter. These spatially indexed ratings are then leveraged by VOTERS decision making modules to plan the optimum M&R operations and predict the future budget needs. In 2014, VOTERS inspection results were validated by comparing them to the outputs of recent professionally done condition surveys of a local engineering firm for 300 miles of Massachusetts roads. Success of the VOTERS project portrays rapid, intelligent, and comprehensive evaluation of tomorrow's transportation infrastructure to increase public's safety, vitalize the economy, and deter catastrophic failures.

  7. Massive Hemorrhage from Internal Carotid Artery Pseudoaneurysm Successfully Treated by Transcatheter Arterial Embolization with Assessment of Regional Cerebral Oxygenation

    SciTech Connect

    Kakizawa, Hideaki Toyota, Naoyuki; Hieda, Masashi; Hirai, Nobuhiko; Tachikake, Toshihiro; Horiguchi, Jun; Ito, Katsuhide

    2005-05-15

    A 54-year-old male presented with intermittent massive hemorrhage from recurrent oropharyngeal cancer. The angiogram showed the encasements at the main trunk of the left internal carotid artery (ICA) and external carotid artery (ECA). Transcatheter arterial embolization (TAE) of the ECA with gelatin sponge particles and microcoils was performed. However, hemorrhage recurred several hours after the initial TAE. The second angiogram showed a large pseudoaneurysm of the ICA developing at the encasement on the initial angiogram. As a simple neurologic test, regional cerebral oxygenation (rSO{sub 2}) was assessed with and without manual compression of the common carotid artery (CCA). With compression of the left CCA, the rSO{sub 2} did not change. We therefore performed isolation of the pseudoaneurysm. We embolized proximally and distally to the ICA pseudoaneurysm with microcoils and the pseudoaneurysm disappeared. No major complications occurred and no massive hemorrhage recurred until death from the cancer. TAE was an effective treatment for massive hemorrhage caused by tumor invasion to ICA. Assessment of rSO{sub 2} was a simple and useful neurologic test predicting the cerebral blood flow to prevent complications of TAE.

  8. Anemia and Oxygen Delivery.

    PubMed

    Bliss, Stuart

    2015-09-01

    Clinical assessment of tissue oxygenation is challenging. Anemia reflects a decreased oxygen carrying capacity of the blood and its significance in the perioperative setting relates largely to the associated risk of insufficient oxygen delivery and cellular hypoxia. Until meaningful clinical measures of tissue oxygenation are available in veterinary practice, clinicians must rely on evaluation of a patient's hemodynamic and ventilatory performance, along with biochemical and hemogasometric measurements. Blood transfusion is used commonly for treatment of perioperative anemia, and may improve tissue oxygenation by normalizing the rheologic properties of blood and enhancing perfusion, independent of increases in oxygen carrying capacity. PMID:26033442

  9. DEVELOPMENT OF AN INSPECTION PLATFORM AND A SUITE OR SENSORS FOR ASSESSING CORROSION AND MECHANICAL DAMAGE ON UNPIGGABLE TRANSMISSION MAINS

    SciTech Connect

    George C. Vradis

    2004-02-01

    This development program is a joint effort among the Northeast Gas Association (formerly New York Gas Group), Foster-Miller, Inc., GE Oil & Gas (PII), and the US Department of Energy (DOE) through the National Energy Technology Laboratory (NETL). The total cost of the project is $772,525, with the National Energy Technology Laboratory of the US Department of Energy contributing $572,525, and the Northeast Gas Association contributing $200,000. The present report summarizes the accomplishments of the project during its fifth three-month period (from October 2003 through December 2003). The efforts of the project focused during this period in completing the assessment of the tether technology, which is intended to be used as the means of communication between robot and operator, in completing the design of the MFL sensor modules, and in completing the kinematic studies and tractor design. In addition, work on the ovality sensor has been completed, while work on system integration is nearly complete. Results to date indicate that the robotic system under design will be able to meet most of the design specifications initially prescribed. The kinematic analysis shows that from a locomotor point of view an inspection of a 16 inch-24 inch pipe size range with a single platform is most likely possible. However, the limitations imposed by the sensor are more restrictive, final preliminary design results showing that in order to cover this pipe range, two different sensor systems will be needed; one for the 16 inch-20 inch pipe size range and one for the 20 inch-24 inch range. Finally, the analysis has shown that tether operation will be limited to flows of less than 30 ft/sec; these results will have to be confirmed experimentally during the next phase of work.

  10. Oxygen ion conducting materials

    DOEpatents

    Vaughey, John; Krumpelt, Michael; Wang, Xiaoping; Carter, J. David

    2005-07-12

    An oxygen ion conducting ceramic oxide that has applications in industry including fuel cells, oxygen pumps, oxygen sensors, and separation membranes. The material is based on the idea that substituting a dopant into the host perovskite lattice of (La,Sr)MnO.sub.3 that prefers a coordination number lower than 6 will induce oxygen ion vacancies to form in the lattice. Because the oxygen ion conductivity of (La,Sr)MnO.sub.3 is low over a very large temperature range, the material exhibits a high overpotential when used. The inclusion of oxygen vacancies into the lattice by doping the material has been found to maintain the desirable properties of (La,Sr)MnO.sub.3, while significantly decreasing the experimentally observed overpotential.

  11. Oxygen ion conducting materials

    DOEpatents

    Carter, J. David; Wang, Xiaoping; Vaughey, John; Krumpelt, Michael

    2004-11-23

    An oxygen ion conducting ceramic oxide that has applications in industry including fuel cells, oxygen pumps, oxygen sensors, and separation membranes. The material is based on the idea that substituting a dopant into the host perovskite lattice of (La,Sr)MnO.sub.3 that prefers a coordination number lower than 6 will induce oxygen ion vacancies to form in the lattice. Because the oxygen ion conductivity of (La,Sr)MnO.sub.3 is low over a very large temperature range, the material exhibits a high overpotential when used. The inclusion of oxygen vacancies into the lattice by doping the material has been found to maintain the desirable properties of (La,Sr)MnO.sub.3, while significantly decreasing the experimentally observed overpotential.

  12. Oxygen ion conducting materials

    DOEpatents

    Vaughey, John; Krumpelt, Michael; Wang, Xiaoping; Carter, J. David

    2003-01-01

    An oxygen ion conducting ceramic oxide that has applications in industry including fuel cells, oxygen pumps, oxygen sensors, and separation membranes. The material is based on the idea that substituting a dopant into the host perovskite lattice of (La,Sr)MnO.sub.3 that prefers a coordination number lower than 6 will induce oxygen ion vacancies to form in the lattice. Because the oxygen ion conductivity of (La,Sr)MnO.sub.3 is low over a very large temperature range, the material exhibits a high overpotential when used. The inclusion of oxygen vacancies into the lattice by doping the material has been found to maintain the desirable properties of (La,Sr)MnO.sub.3, while significantly decreasing the experimentally observed overpotential.

  13. Near infrared spectroscopy for non-invasive assessment of intracranial haemoglobin oxygenation in an in vitro model of the calf head.

    PubMed

    Pringle, J; Art, T; Lekeux, P

    1998-01-01

    An in vitro model of the calf head was used to examine the ability of near infrared spectroscopy (NIRS) to non-invasively determine oxygenation events within the calf head. The brains were removed from 16 calf skulls and replaced with oxygenated dilutions of calf blood that had the oxygen progressively decreased from PO2 > 110 mmHg to < 10 mmHg. Appropriate placement of the lighting source and sensor (optodes) was examined, as were the influences of skull thickness and overlying skin of the skull (including colour). The changes in haemaglobin oxygenation in the model calf head, as observed by NIRS, were highly correlated to PO2 changes in all 16 calf skulls examined (mean r2=0.91, range 0.71 to 0.99). There was a trend for optode positioning to achieve optimal NIRS signals over the middle of the frontal bone in a longitudinal axis and with optodes spaced 4 cm apart, but with the large variation between calf heads this was not shown to be significantly different from other sites tested. The presence of skin over the skull had a significant damping effect on the NIRS signal when compared with the bare skull (P<0.01) but it was not possible to detect a difference in this damping effect between black and white coloured skin. All but the two thickest skulls (13 and 14 mm frontal bone thickness) appeared to allow sufficiently strong NIRS signals of changes in haemoglobin oxygenation. This study showed that NIRS can be used for non-invasive study of oxygenation events within the cranial cavity of calves, and established some guidelines and limitations for its use in this species. PMID:9839886

  14. Assessment of capacity sensors for monitoring soil water content in ecological orchards

    NASA Astrophysics Data System (ADS)

    Patrícia Prazeres Marques, Karina; Horcajo, Daniel; Rodriguez-Sinobas, Leonor

    2014-05-01

    Water is an important element for soil tillage and crop development. Its proper management is essential for the development of plants, by preventing excess or shortage in water application. Soil water content is affected by the soil-water-plant system and its monitoring is a required within a sustainable agriculture framework respectful with the natural environment. Thus, the aim of this study was to evaluate the performance of capacitive sensors in monitoring soil moisture from organic orchards. An experimental text was carried out at the Hydraulics Laboratory of the Agricultural Engineering School in the Polytechnic University of Madrid (Spain). Soil samples were collected within the 0-20 cm depth layers from the university organic orchard. The samples were air dried and subsequently sieved in a 2 mm mesh sieve, removing roots and coarse fractions and keeping the fine soil. The amount of fine soil was calculated from the soil density and the soil samples were compacted to obtain the relative volume that corresponded to their density. The measurements were carried out in dry and in saturated soil and, also in samples where soil was stirring with: 150 cm³, 300 cm³ and 450 cm³ of water. A 1890 ml container was used to hold the fine soil and the soil moisture sensor ECH2O, type 10 HS (Decagon Devices, Inc.) was placed horizontally at 5 cm depth. Soil water readings were recorded on a datalogger Em5b from the same manufacturer. The results showed that the capacitive sensor has a linear response to soil moisture content. Its value was overestimated in comparison to the volumetric values and the largest errors (about 8%) were observed in the soils with high moisture contents. Overall, these results point out that the ECH2O sensor, model 10 HS, could determine with sufficient accuracy the volumetric soil water content from organic orchards although it could be further improved by "in situ" calibration.

  15. Assessing the capability of EOS sensors in measuring ocean-atmosphere moisture exchange

    NASA Technical Reports Server (NTRS)

    Liu, W. T.

    1985-01-01

    As part of the Science Synergism Studies to identify interdisciplinary Scientific studies, which could be addressed by the Environmental Observing System (EOS), the techniques being developed to measure ocean-atmosphere moisture exchanges using satellite sensors were evaluated. Studies required to use sensors proposed for EOS were examined. A method has been developed to compute the moisture flux using the wind speed, sea surface temperature, and preciptable water measured by satellite sensors. It relies on a statistical model which predicts surface-level humidity from precipitable water. The Scanning Multichannel Microwave Radiometer (SMMR) measures all 3 parameters and was found to be sensitive to the annual cycle and large interannual variations such as the 1982 to 1983 El Nino. There are systematic differences between geophysical parameters measured by Nimbus/SMMR and in situ measurements. After quadratic trends and crosstalks were removed from the parameters through multivariate regressions, the latent heat fluxes computed from SMMR agree with those computed from ship reports to within 30 W/sq m. The poor quality of ship reports may be the cause of a portion of this scatter. Similar results are found using SEASAT/SMMR data. When the scatterometer winds were used instead of the SMMR winds, the difference between the satellite fluxes and the ship fluxes was reduced.

  16. Performance assessment of frequency plane filters applied to track association and sensor registration

    NASA Astrophysics Data System (ADS)

    Stanek, Clay J.; Javidi, Bahram; Yanni, P.

    2003-09-01

    The current generation of correlation systems attempting to provide a Single Integrated Picture (SIP) have concentrated on improving quality from the situational awareness (SA) and tracking perspective with limited success, while having not addressed the combat identification (CID) issue at all. Furthermore, decision time has lengthened, not decreased, as more and more sensor data are made available to the commanders; much of which is video in origin. Many efforts are underway to build a network of sensors including the Army's Future Combat System (FCS), Air Force Multi-mission Command and Control Aircraft (MC2A), Network-Centric Collaborative Targeting (NCCT), and the follow-on to the Navy's Cooperative Engagement Capability (CEC). Each of these programs has the potential to increase precision of the targeting data with successful correlation algorithms while eliminating dual track reports, but none have combined or will combine disparate sensor data into a cohesive target with a high confidence of identification. In this paper, we address an architecture that solves the track correlation problem using frequency plane pattern recognition techniques that also can provide CID capability. Also, we discuss statistical considerations and performance issues.

  17. Assessing the diagnostic information in the response patterns of a temperature-modulated tin oxide gas sensor

    NASA Astrophysics Data System (ADS)

    Hosseini-Golgoo, S. M.; Hossein-Babaei, F.

    2011-03-01

    The transient response patterns of a tin oxide chemoresistive gas sensor, temperature-modulated by the application of staircase voltage waveforms to its microheater, to five different volatile organic compounds were compared with respect to their target gas discriminating features. These patterns were divided into a number of segments, each corresponding to a temperature transition at the surface of the tin oxide pallet. The effectiveness of the gas discriminating information content of each segment was quantitatively assessed utilizing Fisher's discriminant ratio calculations in a 3D feature space. It was established that the amount of the useful information in a response segment depended on the corresponding temperature transition; larger pallet temperature transitions rendered more diagnostic information. Similar assessments were carried out for the different combinations of these segments. The results facilitated, for the first time, a comparative analysis of the levels of the correlated (redundant) and uncorrelated information in the different response segments. It was shown that the response segments occurring at or near the nominal operating temperature of the sensor contained most of the effective information, while those at low temperatures contained mostly the redundant or indiscriminative information. The results help minimize the temperature modulation duration required for gas recognition.

  18. Evaluation of Multi-Resolution Satellite Sensors for Assessing Water Quality and Bottom Depth of Lake Garda

    PubMed Central

    Giardino, Claudia; Bresciani, Mariano; Cazzaniga, Ilaria; Schenk, Karin; Rieger, Patrizia; Braga, Federica; Matta, Erica; Brando, Vittorio E.

    2014-01-01

    In this study we evaluate the capabilities of three satellite sensors for assessing water composition and bottom depth in Lake Garda, Italy. A consistent physics-based processing chain was applied to Moderate Resolution Imaging Spectroradiometer (MODIS), Landsat-8 Operational Land Imager (OLI) and RapidEye. Images gathered on 10 June 2014 were corrected for the atmospheric effects with the 6SV code. The computed remote sensing reflectance (Rrs) from MODIS and OLI were converted into water quality parameters by adopting a spectral inversion procedure based on a bio-optical model calibrated with optical properties of the lake. The same spectral inversion procedure was applied to RapidEye and to OLI data to map bottom depth. In situ measurements of Rrs and of concentrations of water quality parameters collected in five locations were used to evaluate the models. The bottom depth maps from OLI and RapidEye showed similar gradients up to 7 m (r = 0.72). The results indicate that: (1) the spatial and radiometric resolutions of OLI enabled mapping water constituents and bottom properties; (2) MODIS was appropriate for assessing water quality in the pelagic areas at a coarser spatial resolution; and (3) RapidEye had the capability to retrieve bottom depth at high spatial resolution. Future work should evaluate the performance of the three sensors in different bio-optical conditions. PMID:25517691

  19. Evaluation of multi-resolution satellite sensors for assessing water quality and bottom depth of Lake Garda.

    PubMed

    Giardino, Claudia; Bresciani, Mariano; Cazzaniga, Ilaria; Schenk, Karin; Rieger, Patrizia; Braga, Federica; Matta, Erica; Brando, Vittorio E

    2014-01-01

    In this study we evaluate the capabilities of three satellite sensors for assessing water composition and bottom depth in Lake Garda, Italy. A consistent physics-based processing chain was applied to Moderate Resolution Imaging Spectroradiometer (MODIS), Landsat-8 Operational Land Imager (OLI) and RapidEye. Images gathered on 10 June 2014 were corrected for the atmospheric effects with the 6SV code. The computed remote sensing reflectance (Rrs) from MODIS and OLI were converted into water quality parameters by adopting a spectral inversion procedure based on a bio-optical model calibrated with optical properties of the lake. The same spectral inversion procedure was applied to RapidEye and to OLI data to map bottom depth. In situ measurements of Rrs and of concentrations of water quality parameters collected in five locations were used to evaluate the models. The bottom depth maps from OLI and RapidEye showed similar gradients up to 7 m (r = 0.72). The results indicate that: (1) the spatial and radiometric resolutions of OLI enabled mapping water constituents and bottom properties; (2) MODIS was appropriate for assessing water quality in the pelagic areas at a coarser spatial resolution; and (3) RapidEye had the capability to retrieve bottom depth at high spatial resolution. Future work should evaluate the performance of the three sensors in different bio-optical conditions. PMID:25517691

  20. An Assessment of the SEA Multi-Element Sensor for Liquid Water Content Calibration of the NASA GRC Icing Research Tunnel

    NASA Technical Reports Server (NTRS)

    Steen, Laura E.; Ide, Robert F.; Van Zante, Judith F.

    2015-01-01

    The NASA Glenn Icing Research tunnel has been using an Icing Blade technique to measure cloud liquid water content (LWC) since 1980. The IRT conducted tests with SEA Multi-Element sensors from 2009 to 2011 to assess their performance in measuring LWC. These tests revealed that the Multi-Element sensors showed some significant advantages over the Icing Blade, particularly at higher water contents, higher impingement rates, and large drop sizes. Results of these and other tests are presented here.

  1. Assessment of diffusion parameters of new passive samplers using optical chemical sensor for on-site measuring formaldehyde in indoor air: experimental and numerical studies.

    PubMed

    Vignau-Laulhere, Jane; Mocho, Pierre; Plaisance, Hervé; Raulin, Katarzyna; Desauziers, Valérie

    2016-03-01

    New passive samplers using a sensor consisting of a sol-gel matrix entrapping Fluoral-P as sampling media were developed for the determination of formaldehyde in indoor air. The reaction between Fluoral-P and formaldehyde produces a colored compound which is quantified on-site by means of a simple optical reading module. The advantages of this sensor are selectivity, low cost, ppb level limit of detection, and on-site direct measurement. In the development process, it is necessary to determine the sampling rate, a key parameter that cannot be directly assessed in the case of diffusive samplers using optical chemical sensor. In this study, a methodology combining experimental tests and numerical modeling is proposed and applied at five different radial diffusive samplers equipped with the same optical chemical sensor to assess the sampled material flows and sampling rates. These radial diffusive samplers differ in the internal volume of the sampler (18.97 and 6.14 cm(3)), the position of sensor inside the sampler (in front and offset of 1.2 cm above the membrane) and the width of the diffusion slot (1.4 and 5.9 mm). The influences of these three parameters (internal volume, position of sensor inside the sampler, and width of the diffusion slot) were assessed and discussed with regard to the formaldehyde sampling rate and water uptake by sensor (potential interference of measure). Numerical simulations based on Fick's laws are in agreement with the experimental results and provide to estimate the effective diffusion coefficient of formaldehyde through the membrane (3.50 × 10(-6) m(2) s(-1)). Conversion factors between the sensor response, sampled formaldehyde mass and sampling rate were also assessed. PMID:26847188