Thermal and Surface Evaluation on The Process of Forming a Cu2O/CuO Semiconductor Photocatalyst on a Thin Copper Plate

NASA Astrophysics Data System (ADS)

Zainul, R.; Oktavia, B.; Dewata, I.; Efendi, J.

2018-04-01

This research aims to investigate the process of forming a multi-scale copper oxide semiconductor (CuO/Cu2O) through a process of calcining a copper plate. The changes that occur during the formation of the oxide are thermally and surface evaluated. Evaluation using Differential Thermal Analysis (DTA) obtained by surface change of copper plate happened at temperature 380°C. Calcination of oxide formation was carried out at temperature 380°C for 1 hour. Surface evaluation process by using Scanning Electron Microscope (SEM) surface and cross-section, to determine diffusion of oxide formation on copper plate. The material composition is monitored by XRF and XRD to explain the process of structural and physical changes of the copper oxide plate formed during the heating process. The thickness of Cu plates used is 200-250 μm. SEM analysis results, the oxygen atom interruption region is in the range of 20-30 μm, and diffuses deeper during thermal oxidation process. The maximum diffusion depth of oxygen atoms reaches 129 μm.

Metal oxide nanoparticle mediated enhanced Raman scattering and its use in direct monitoring of interfacial chemical reactions.

PubMed

Li, Li; Hutter, Tanya; Finnemore, Alexander S; Huang, Fu Min; Baumberg, Jeremy J; Elliott, Stephen R; Steiner, Ullrich; Mahajan, Sumeet

2012-08-08

Metal oxide nanoparticles (MONPs) have widespread usage across many disciplines, but monitoring molecular processes at their surfaces in situ has not been possible. Here we demonstrate that MONPs give highly enhanced (×10(4)) Raman scattering signals from molecules at the interface permitting direct monitoring of their reactions, when placed on top of flat metallic surfaces. Experiments with different metal oxide materials and molecules indicate that the enhancement is generic and operates at the single nanoparticle level. Simulations confirm that the amplification is principally electromagnetic and is a result of optical modulation of the underlying plasmonic metallic surface by MONPs, which act as scattering antennae and couple light into the confined region sandwiched by the underlying surface. Because of additional functionalities of metal oxides as magnetic, photoelectrochemical and catalytic materials, enhanced Raman scattering mediated by MONPs opens up significant opportunities in fundamental science, allowing direct tracking and understanding of application-specific transformations at such interfaces. We show a first example by monitoring the MONP-assisted photocatalytic decomposition reaction of an organic dye by individual nanoparticles.

Application of confocal Raman micro-spectroscopy for label-free monitoring of oxidative stress in living bronchial cells

NASA Astrophysics Data System (ADS)

Surmacki, Jakub M.; Quirós Gonzalez, Isabel; Bohndiek, Sarah E.

2018-02-01

Oxidative stress in cancer is implicated in tumor progression, being associated with increased therapy resistance and metastasis. Conventional approaches for monitoring oxidative stress in tissue such as high-performance liquid chromatography and immunohistochemistry are bulk measurements and destroy the sample, meaning that longitudinal monitoring of cancer cell heterogeneity remains elusive. Raman spectroscopy has the potential to overcome this challenge, providing a chemically specific, label free readout from single living cells. Here, we applied a standardized protocol for label-free confocal Raman micro-spectroscopy in living cells to monitor oxidative stress in bronchial cells. We used a quartz substrate in a commercial cell chamber contained within a microscope incubator providing culture media for cell maintenance. We studied the effect of a potent reactive oxygen species inducer, tert-butyl hydroperoxide (TBHP), and antioxidant, N-acetyl-L-cysteine (NAC) on living cells from a human bronchial epithelial cells (HBEC). We found that the Raman bands corresponding to nucleic acids, proteins and lipids were significantly different (p<0.05) for control, TBHP, and NAC. Encouragingly, partial least squares discriminant analysis applied to our data showed high sensitivity and specificity for identification of control (87.3%, 71.7%), NAC (92.3%, 85.1%) and TBHP (86.9%, 92.9%). These results suggest that confocal Raman micro-spectroscopy may be able to monitor the biological impact of oxidative and reductive processes in cells, hence enabling longitudinal studies of oxidative stress in therapy resistance and metastasis at the single cell level.

A survey of analytical methods employed for monitoring of Advanced Oxidation/Reduction Processes for decomposition of selected perfluorinated environmental pollutants.

PubMed

Trojanowicz, Marek; Bobrowski, Krzysztof; Szostek, Bogdan; Bojanowska-Czajka, Anna; Szreder, Tomasz; Bartoszewicz, Iwona; Kulisa, Krzysztof

2018-01-15

The monitoring of Advanced Oxidation/Reduction Processes (AO/RPs) for the evaluation of the yield and mechanisms of decomposition of perfluorinated compounds (PFCs) is often a more difficult task than their determination in the environmental, biological or food samples with complex matrices. This is mostly due to the formation of hundreds, or even thousands, of both intermediate and final products. The considered AO/RPs, involving free radical reactions, include photolytic and photocatalytic processes, Fenton reactions, sonolysis, ozonation, application of ionizing radiation and several wet oxidation processes. The main attention is paid to the most commonly occurring PFCs in the environment, namely PFOA and PFOS. The most powerful and widely exploited method for this purpose is without a doubt LC/MS/MS, which allows the identification and trace quantitation of all species with detectability and resolution power depending on the particular instrumental configurations. The GC/MS is often employed for the monitoring of volatile fluorocarbons, confirming the formation of radicals in the processes of C‒C and C‒S bonds cleavage. For the direct monitoring of radicals participating in the reactions of PFCs decomposition, the molecular spectrophotometry is employed, especially electron paramagnetic resonance (EPR). The UV/Vis spectrophotometry as a detection method is of special importance in the evaluation of kinetics of radical reactions with the use of pulse radiolysis methods. The most commonly employed for the determination of the yield of mineralization of PFCs is ion-chromatography, but there is also potentiometry with ion-selective electrode and the measurements of general parameters such as Total Organic Carbon and Total Organic Fluoride. The presented review is based on about 100 original papers published in both analytical and environmental journals. Copyright © 2017 Elsevier B.V. All rights reserved.

Physical and Chemical Processes in Flames

DTIC Science & Technology

2010-02-15

7. "An efficient reduced mechanism for methane oxidation with NOx chemistry ," by T. F. Lu and C. K. Law, Paper No. C17, Fifth US Combustion Meeting... Mechanical and Aerospace Engineering Princeton University Princeton, NJ 08544 9. SPONSORING I MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR...TERMS Laminar flame speeds; ignition temperatures; extinction limits; mechanism reduction; skeletal mechanism ; CO/H2 oxidation; ethy lene oxidation

A FLUORESCENCE BASED ASSAY FOR DNA DAMAGE INDUCED BY STYRENE OXIDE

EPA Science Inventory

A rapid and simple assay to detect DNA damage to calf thymus DNA caused by styrene oxide (SO) is reported. This assay is based on changes observed in the melting and annealing behavior of the damaged DNA. The melting annealing process was monitored using a fluorescence indicat...

Off-line wafer level reliability control: unique measurement method to monitor the lifetime indicator of gate oxide validated within bipolar/CMOS/DMOS technology

NASA Astrophysics Data System (ADS)

Gagnard, Xavier; Bonnaud, Olivier

2000-08-01

We have recently published a paper on a new rapid method for the determination of the lifetime of the gate oxide involved in a Bipolar/CMOS/DMOS technology (BCD). Because this previous method was based on a current measurement with gate voltage as a parameter needing several stress voltages, it was applied only by lot sampling. Thus, we tried to find an indicator in order to monitor the gate oxide lifetime during the wafer level parametric test and involving only one measurement of the device on each wafer test cell. Using the Weibull law and Crook model, combined with our recent model, we have developed a new test method needing only one electrical measurement of MOS capacitor to monitor the quality of the gate oxide. Based also on a current measurement, the parameter is the lifetime indicator of the gate oxide. From the analysis of several wafers, we gave evidence of the possibility to detect a low performance wafer, which corresponds to the infantile failure on the Weibull plot. In order to insert this new method in the BCD parametric program, a parametric flowchart was established. This type of measurement is an important challenges, because the actual measurements, breakdown charge, Qbd, and breakdown electric field, Ebd, at parametric level and Ebd and interface states density, Dit during the process cannot guarantee the gate oxide lifetime all along fabrication process. This indicator measurement is the only one, which predicts the lifetime decrease.

Thermodynamics of Iron Oxidation in Metallurgical Slags

NASA Astrophysics Data System (ADS)

Matousek, Jan

2012-11-01

The state of oxidation of a pyrometallurgical process, given by the partial pressure of oxygen and the temperature, is one of the important properties monitored and controlled in the smelting and refining of iron and the nonferrous metals. This article reviews the thermodynamic background for this quantity and examines some empirical methods for its estimation and use. The emphasis is on copper smelting, but the same principles apply to iron, nickel, lead, and zinc processes.

Treatment of reverse-osmosis concentrate of printing and dyeing wastewater by electro-oxidation process with controlled oxidation-reduction potential (ORP).

PubMed

Wang, Jiade; Zhang, Tian; Mei, Yu; Pan, Bingjun

2018-06-01

Reverse osmosis concentrate (ROC) of printing and dyeing wastewater remains as a daunting environmental issue, which is characterized by high salinity, chemical oxygen demand (COD), chroma and low biodegradability. In this study electro-oxidation process (PbO 2 /Ti electrode) coupled with oxidation-reduction potential (ORP) online monitor was applied to treat such a ROC effluent. The results show that with the increase of specific electrical charge (Q sp ), the removal efficiencies of COD, TN and chroma increased significantly at the incipience and then reached a gentle stage; the optimal total current efficiency (12.04 kWh m -3 ) was obtained with the current density of 10 mA cm -2 (Q sp , 3.0 Ah L -1 ). Meanwhile, some inorganic ions can be simultaneously removed to varying degrees. FTIR analyses indicated that the macromolecular organics were decomposed into smaller molecules. A multi-parameter linear relationship between ORP and Q sp , COD and Cl - concentration was established, which can quantitatively reflect the effect of current density, chloride ion concentration, pollutants and reaction time on the performance of the electro-oxidation system. As compared to a traditional constant-current system, the constant-ORP system developed in this study (through the back-propagation neural network [BPN] model with ORP monitoring) approximately reduced the energy cost by 24-29%. The present work is expected to provide a potential alternative in optimizing the electro-oxidation process. Copyright © 2018 Elsevier Ltd. All rights reserved.

Optical in situ monitoring of plasma-enhanced atomic layer deposition process

NASA Astrophysics Data System (ADS)

Zeeshan Arshad, Muhammad; Jo, Kyung Jae; Kim, Hyun Gi; Jeen Hong, Sang

2018-06-01

An optical in situ process monitoring method for the early detection of anomalies in plasma process equipment is presented. Cyclic process steps of precursor treatment and plasma reaction for the deposition of an angstrom-scale film increase their complexity to ensure the process quality. However, a small deviation in process parameters, for instance, gas flow rate, process temperature, or RF power, may jeopardize the deposited film quality. As a test vehicle for the process monitoring, we have investigated the aluminum-oxide (Al2O3) encapsulation process in plasma-enhanced atomic layer deposition (PEALD) to form a moisture and oxygen diffusion barrier in organic-light emitting diodes (OLEDs). By optical in situ monitoring, we successfully identified the reduction in oxygen flow rates in the reaction steps, which resulted in a 2.67 times increase in the water vapor transmission ratio (WVTR) of the deposited Al2O3 films. Therefore, we are convinced that the suggested in situ monitoring method is useful for the detection of process shifts or drifts that adversely affect PEALD film quality.

A novel rapid analysis using mass spectrometry to evaluate downstream refolding of recombinant human insulin-like growth factor-1 (mecasermin).

PubMed

Furuki, Kenichiro; Toyo'oka, Toshimasa; Yamaguchi, Hideto

2017-08-15

Mecasermin is used to treat elevated blood sugar as well as growth-hormone-resistant Laron-type dwarfism. Mecasermin isolated from inclusion bodies in extracts of E. coli must be refolded to acquire sufficient activity. However, there is no rapid analytical method for monitoring refolding during the purification process. We prepared mecasermin drug product, in-process samples during the oxidation of mecasermin, forced-reduced mecasermin, and aerially oxidized mecasermin after forced reduction. Desalted mecasermin samples were analyzed using MALDI-ISD. The peak intensity ratio of product to precursor ion was determined. The charge-state distribution (CSD) of mecasermin ions was evaluated using ESI-MS coupled with SEC-mode HPLC. The drift time and collision cross-sectional area (CCS) of mecasermin ions were evaluated using ESI-IMS-MS coupled with SEC-mode HPLC. MALDI-ISD data, CSD values determined using ESI-MS, and the CCS acquired using ESI-IMS-MS revealed the relationship between the folded and unfolded proteoforms of forced-reduced mecasermin and aerially oxidized mecasermin with the free-SH:protein ratio of mecasermin drug product. The CCS area, which is determined using ESI-IMS-MS, provided proteoform information through rapid monitoring (<2 min) of in-process samples during the manufacture of mecasermin. ESI-IMS-MS coupled with SEC-mode HPLC is a rapid and robust method for analyzing the free-SH:protein ratio of mecasermin that allows proteoform changes to be evaluated and monitored during the oxidation of mecasermin. ESI-IMS-MS is applicable as a process analytical technology tool for identifying the "critical quality attributes" and implementing "quality by design" for manufacturing mecasermin. Copyright © 2017 John Wiley & Sons, Ltd.

Study of jojoba oil aging by FTIR.

PubMed

Le Dréau, Y; Dupuy, N; Gaydou, V; Joachim, J; Kister, J

2009-05-29

As the jojoba oil was used in cosmetic, pharmaceutical, dietetic food, animal feeding, lubrication, polishing and bio-diesel fields, it was important to study its aging at high temperature by oxidative process. In this work a FT-MIR methodology was developed for monitoring accelerate oxidative degradation of jojoba oils. Principal component analysis (PCA) was used to differentiate various samples according to their origin and obtaining process, and to differentiate oxidative conditions applied on oils. Two spectroscopic indices were calculated to report simply the oxidation phenomenon. Results were confirmed and deepened by multivariate curve resolution-alternative least square method (MCR-ALS). It allowed identifying chemical species produced or degraded during the thermal treatment according to a SIMPLISMA pretreatment.

Degradation of thiamethoxam by the synergetic effect between anodic oxidation and Fenton reactions.

PubMed

Meijide, J; Gómez, J; Pazos, M; Sanromán, M A

2016-12-05

In this work, a comparative study using anodic oxidation, Fenton and electro-Fenton treatments was performed in order to determine the synergic effect for the removal of thiamethoxan. The results determined that electro-Fenton process showed high efficiency in comparison with Fenton or anodic oxidation. After that, this hybrid process was optimized and the influence of iron catalyst concentration and applied current intensity on the degradation and mineralization were evaluated. Degradation profiles were monitored by high performance liquid chromatography (HPLC) being satisfactorily described by pseudo-first order kinetic model. At the optimal experimental conditions (300mA and 0.2mM Fe(+2)), the complete degradation of thiamethoxam was achieved after 10min. On the other hand, mineralization of thiamethoxam was monitored by total organic carbon (TOC) decay reaching more than 92% of TOC removal after 8h. Furthermore, a plausible mineralization pathway for the thiamethoxam degradation was proposed based on the identification of by-products such as aromatic intermediates, carboxylic acids and inorganic ions released throughout electro-Fenton process. Copyright © 2016 Elsevier B.V. All rights reserved.

In Situ Monitoring of Chemical Reactions at a Solid-Water Interface by Femtosecond Acoustics.

PubMed

Shen, Chih-Chiang; Weng, Meng-Yu; Sheu, Jinn-Kong; Yao, Yi-Ting; Sun, Chi-Kuang

2017-11-02

Chemical reactions at a solid-liquid interface are of fundamental importance. Interfacial chemical reactions occur not only at the very interface but also in the subsurface area, while existing monitoring techniques either provide limited spatial resolution or are applicable only for the outmost atomic layer. Here, with the aid of the time-domain analysis with femtosecond acoustics, we demonstrate a subatomic-level-resolution technique to longitudinally monitor chemical reactions at solid-water interfaces, capable of in situ monitoring even the subsurface area under atmospheric conditions. Our work was proven by monitoring the already-known anode oxidation process occurring during photoelectrochemical water splitting. Furthermore, whenever the oxide layer thickness equals an integer  number of the effective atomic layer thickness, the measured acoustic echo will show higher signal-to-noise ratios with reduced speckle noise, indicating the quantum-like behavior of this coherent-phonon-based technique.

In situ loading of well-dispersed silver nanoparticles on nanocrystalline magnesium oxide for real-time monitoring of catalytic reactions by surface enhanced Raman spectroscopy.

PubMed

Zhang, Kaige; Li, Gongke; Hu, Yuling

2015-10-28

The surface-enhanced Raman spectroscopy (SERS) technique is of great importance for insight into the transient reaction intermediates and mechanistic pathways involved in heterogeneously catalyzed chemical reactions under actual reaction conditions, especially in water. Herein, we demonstrate a facile method for in situ synthesis of nanocrystalline magnesium oxide-Ag(0) (nano MgO-Ag(0)) hybrid nanomaterials with dispersed Ag nanoparticles (Ag NPs) on the surface of nanocrystalline magnesium oxide (nano MgO) via Sn(2+) linkage and reduction. As a benefit from the synergy effect of nano MgO and Ag NPs, the nano MgO-Ag(0) exhibited both excellent SERS and catalytic activities for the reduction of 4-nitrothiophenol in the presence of NaBH4. The nano MgO-Ag(0) was used for real-time monitoring of the catalytic reaction process of 4-nitrothiophenol to 4-aminothiophenol in an aqueous medium by observing the SERS signals of the reactant, intermediate and final products. The intrinsic reaction kinetics and reaction mechanism of this reaction were also investigated. This SERS-based synergy technique provides a novel approach for quantitative in situ monitoring of catalytic chemical reaction processes.

Kinetics and thermodynamics of oxidation mediated reaction in L-cysteine and its methyl and ethyl esters in dimethyl sulfoxide-d6 by NMR spectroscopy

NASA Astrophysics Data System (ADS)

Dougherty, Ryan J.; Singh, Jaideep; Krishnan, V. V.

2017-03-01

L-Cysteine (L-Cys), L-Cysteine methyl ester (L-CysME) or L-Cysteine ethyl ester (L-CysEE), when dissolved in dimethyl sulfoxide, undergoes an oxidation process. This process is slow enough and leads to nuclear magnetic resonance (NMR) spectral changes that could be monitored in real time. The oxidation mediated transition is modeled as a pseudo-first order kinetics and the thermodynamic parameters are estimated using the Eyring's formulation. L-Cysteine and their esters are often used as biological models due to the remarkable thiol group that can be found in different oxidation states. This oxidation mediated transition is due to the combination of thiol oxidation to a disulfide followed by solvent-induced effects may be relevant in designing cysteine-based molecular models.

In vivo monitor oxidative burst induced by Cd2+ stress for the oilseed rape (Brassica napus L.) based on electrochemical microbiosensor.

PubMed

Xu, Qiao; Wei, Fang; Wang, Zhan; Yang, Qin; Zhao, Yuan-Di; Chen, Hong

2010-01-01

Since the mechanism of Cd(2+) stress for plants is not clear, an in vivo method to monitor Cd(2+) stress for plants is necessary. However, oxidative burst (OB) is a signal messenger in the process of Cd(2+) stress for plants. To establish an electrochemical method with poly-o-phenylenediamine and Pt microparticle modified Pt electrode (POPD-Pt-MP-Pt) as a microbiosensor for the in vivo detection of oxidative burst induced by Cd(2+) stress in oilseed rape (Brassica napus L.). The optimal fabrication of POPD-Pt-MP-Pt biosensor was achieved. Electrochemical signal was collected by amperometry. After oilseed rape was exposed to 84.9 mM CdCl(2) stress, three oxidative bursts were observed in oilseed rape by amperometry at 3.3 h, 8.4 h and 13.2 h, respectively. However, there was no obvious signal observed in the controlled assay. This contribution presents the in vivo monitoring of the OB process induced by Cd(2+) stress in oilseed rape by POPD-Pt-MP-Pt microbiosensor in real-time. The novel electrochemical microbiosensor not only facilitates the real-time study in plant self-defence response to the adverse environment such as Cd(2+) stress, but also provides an effective tool for probing the self-defence mechanism in plants.

Applicability of samarium(III) complexes for the role of luminescent molecular sensors for monitoring progress of photopolymerization processes and control of the thickness of polymer coatings

NASA Astrophysics Data System (ADS)

Topa, Monika; Ortyl, Joanna; Chachaj-Brekiesz, Anna; Kamińska-Borek, Iwona; Pilch, Maciej; Popielarz, Roman

2018-06-01

Applicability of 15 trivalent samarium complexes as novel luminescent probes for monitoring progress of photopolymerization processes or thickness of polymer coatings by the Fluorescence Probe Technique (FPT) was studied. Three groups of samarium(III) complexes were evaluated in cationic photopolymerization of triethylene glycol divinyl ether monomer (TEGDVE) and free-radical photopolymerization of trimethylolpropane triacrylate (TMPTA). The complexes were the derivatives of tris(4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedionate)samarium(III), tris(4,4,4-trifluoro-1-phenyl-1,3-butanedionate)samarium(III) and tris(4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedionate)samarium(III), which were further coordinated with auxiliary ligands, such as 1,10-phenanthroline, triphenylphosphine oxide, tributylphosphine oxide and trioctylphosphine oxide. It has been found that most of the complexes studied are sensitive enough to be used as luminescent probes for monitoring progress of cationic photopolymerization of vinyl ether monomers over entire range of monomer conversions. In the case of free-radical polymerization processes, the samarium(III) complexes are not sensitive enough to changes of microviscosity and/or micropolarity of the medium, so they cannot be used to monitor progress of the polymerization. However, high stability of luminescence intensity of some of these complexes under free-radical polymerization conditions makes them good candidates for application as thickness sensors for polymer coatings prepared by free-radical photopolymerization. A quantitative relationship between a coating thickness and the luminescence intensity of the samarium(III) probes has been derived and verified experimentally within a broad range of the thicknesses.

In-situ IR spectroscopy as a probe of oxidation/reduction of Ce in nanostructured CeO2

NASA Astrophysics Data System (ADS)

Wu, Weiqiang; Savereide, Louisa Marie; Notestein, Justin; Weitz, Eric

2018-07-01

The redox properties of CeO2 are crucial in its applications in a wide range of catalytic processes. In the present research, in-situ IR spectroscopy is shown to be a viable and convenient method for the characterization of the oxidation state of Ce by monitoring the spin-orbit transition in Ce3+ (2F5/2 → 2F7/2) at ∼2147 cm-1. By monitoring this transition in CeO2 nanorods, the apparent activation energy for the production of oxygen vacancies that accompany the formation of Ce3+ has been determined and is shown to be lower for reduction with cyclohexene than with hydrogen. The bi-exponential kinetics for the formation of oxygen vacancies in CeO2 nanorods is discussed. An application of this method to real time monitoring of the oxidation state of Ce in the oxidation of cyclohexene on vanadia supported on ceria is presented as an example of how this method can be used as an operando probe of reaction mechanisms.

Integrative Advanced Oxidation and Biofiltration for Treating Pharmaceuticals in Wastewater.

PubMed

Lester, Yaal; Aga, Diana S; Love, Nancy G; Singh, Randolph R; Morrissey, Ian; Linden, Karl G

2016-11-01

  Advanced oxidation of active pharmaceutical ingredients (APIs) in wastewater produces transformation products (TPs) that are often more biodegradable than the parent compounds. Secondary effluent from a wastewater treatment plant was treated using UV-based advanced oxidation (LPUV/H2O2 and MPUV/NO3) followed by biological aerated filtration (BAF), and different APIs and their transformation products were monitored. The advanced oxidation processes degraded the APIs by 55-87% (LPUV/H2O2) and 58-95% (MPUV/NO3), while minor loss of APIs was achieved in the downstream BAF system. Eleven TPs were detected following oxidation of carbamazepine (5) and iopromide (6); three key TPs were biodegraded in the BAF system. The other TPs remained relatively constant in the BAF. The decrease in UV absorbance (UVA254) of the effluent in the BAF system was linearly correlated to the degradation of the APIs (for the MPUV/NO3-BAF), and can be applied to monitor the biotransformation of APIs in biological-based systems.

Corrosion Testing of Monofrax K-3 Refractory in Defense Waste Processing Facility (DWPF) Alternate Reductant Feeds

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

Williams, M.; Jantzen, C.; Burket, P.

The Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS) uses a combination of reductants and oxidants while converting high level waste (HLW) to a borosilicate waste form. A reducing flowsheet is maintained to retain radionuclides in their reduced oxidation states which promotes their incorporation into borosilicate glass. For the last 20 years of processing, the DWPF has used formic acid as the main reductant and nitric acid as the main oxidant. During reaction in the Chemical Process Cell (CPC), formate and formic acid release measurably significant H 2 gas which requires monitoring of certain vessel’s vapor spaces.more » A switch to a nitric acid-glycolic acid (NG) flowsheet from the nitric-formic (NF) flowsheet is desired as the NG flowsheet releases considerably less H 2 gas upon decomposition. This would greatly simplify DWPF processing from a safety standpoint as close monitoring of the H 2 gas concentration could become less critical. In terms of the waste glass melter vapor space flammability, the switch from the NF flowsheet to the NG flowsheet showed a reduction of H 2 gas production from the vitrification process as well. Due to the positive impact of the switch to glycolic acid determined on the flammability issues, evaluation of the other impacts of glycolic acid on the facility must be examined.« less

Biomarkers of early genotoxicity and oxidative stress for occupational risk assessment of exposure to styrene in the fibreglass reinforced plastic industry.

PubMed

Cavallo, Delia; Tranfo, Giovanna; Ursini, Cinzia Lucia; Fresegna, Anna Maria; Ciervo, Aureliano; Maiello, Raffaele; Paci, Enrico; Pigini, Daniela; Gherardi, Monica; Gatto, Maria Pia; Buresti, Giuliana; Iavicoli, Sergio

2018-06-10

This study aimed to identify sensitive and not-invasive biomarkers of early genotoxic/oxidative effect for exposure to styrene in the fibreglass reinforced plastic manufacture. We studied 11 workers of a plastic manufacture using open molding process (A), 16 workers of a manufacture using closed process (B) and 12 controls. We evaluated geno/cytotoxic effects on buccal cells by Buccal Micronucleus Cytome (BMCyt) assay and genotoxic/oxidative effects on lymphocytes by Fpg-comet test. On A workers we also evaluated urinary 8oxoGua, 8oxodGuo and 8oxoGuo to investigate oxidative stress. Personal inhalation exposure to styrene was monitored by passive air sampling and GC/MS. Biological monitoring included urinary metabolites mandelic acid (MA) and phenylglyoxylic acid (PGA). The findings show higher styrene exposure, urinary MA + PGA levels and micronucleus frequency in manufacture A. Higher buccal karyolytic cell frequency vs controls were found in both exposed populations. We found in exposed workers, no induction of direct DNA damage but oxidative DNA damage. Fpg-comet assay and urinary oxidized guanine seem to be sensitive biomarkers of oxidative stress and BMCyt assay a good-not invasive biomarker of cyto-genotoxicity at target organ. The study, although limited by the small number of studied subjects, shows the usefulness of used biomarkers in risk assessment of styrene-exposed workers. Copyright © 2018 Elsevier B.V. All rights reserved.

Predicting trace organic compound attenuation by ozone oxidation: Development of indicator and surrogate models.

PubMed

Park, Minkyu; Anumol, Tarun; Daniels, Kevin D; Wu, Shimin; Ziska, Austin D; Snyder, Shane A

2017-08-01

Ozone oxidation has been demonstrated to be an effective treatment process for the attenuation of trace organic compounds (TOrCs); however, predicting TOrC attenuation by ozone processes is challenging in wastewaters. Since ozone is rapidly consumed, determining the exposure times of ozone and hydroxyl radical proves to be difficult. As direct potable reuse schemes continue to gain traction, there is an increasing need for the development of real-time monitoring strategies for TOrC abatement in ozone oxidation processes. Hence, this study is primarily aimed at developing indicator and surrogate models for the prediction of TOrC attenuation by ozone oxidation. To this end, the second-order kinetic equations with a second-phase R ct value (ratio of hydroxyl radical exposure to molecular ozone exposure) were used to calculate comparative kinetics of TOrC attenuation and the reduction of indicator and spectroscopic surrogate parameters, including UV absorbance at 254 nm (UVA 254 ) and total fluorescence (TF). The developed indicator model using meprobamate as an indicator compound and the surrogate models with UVA 254 and TF exhibited good predictive power for the attenuation of 13 kinetically distinct TOrCs in five filtered and unfiltered wastewater effluents (R 2 values > 0.8). This study is intended to help provide a guideline for the implementation of indicator/surrogate models for real-time monitoring of TOrC abatement with ozone processes and integrate them into a regulatory framework in water reuse. Copyright © 2017 Elsevier Ltd. All rights reserved.

Unconstrained Heterogeneous Colloidal Quantum Dots Embedded in GaAs/GaSb Nanovoids

DTIC Science & Technology

2014-04-17

ex-situ techniques when it comes to both CQD integration as well as regrowth, since the surface is free of contaminants and native oxides . 3.0...monitor the growth surface. The growth was started on a GaSb substrate through a thermal oxide desorption process at 540 C and then a GaSb smoothing...reduces the danger of contamination and/or oxidation of the produced CQDs, and also provides for the removal of any gas byproducts from the

Prooxidant effect of α-tocopherol on soybean oil. Global monitoring of its oxidation process under accelerated storage conditions by 1H nuclear magnetic resonance.

PubMed

Martin-Rubio, A S; Sopelana, P; Ibargoitia, M L; Guillén, María D

2018-04-15

The effect of adding α-tocopherol in proportions ranging from 0.002 to 5% in weight on the oxidative stability of soybean oil was studied. For the first time, the oxidation process under accelerated storage conditions including evolution of the molar percentages of the several types of oil acyl groups, and formation and evolution of various kinds of oxidation products comprising hydroperoxides, hydroxy-dienes and other alcohols, epoxides, aldehydes and keto-dienes, was followed by 1 H nuclear magnetic resonance. It is proved that, except in the lowest proportion, α-tocopherol not only exerts a prooxidant effect on soybean oil but also modifies its oxidation pathway, affecting the oxidation products generation rate, their nature, relative proportions and concentrations. It is noticeable that the highest α-tocopherol concentrations induce the generation of some toxic compounds at earlier stages of the thermoxidation process and sometimes in higher concentration, such as certain oxygenated α,β-unsaturated aldehydes and monoepoxides derived from linoleic groups. Copyright © 2017 Elsevier Ltd. All rights reserved.

Degradation of anti-inflammatory drug ketoprofen by electro-oxidation: comparison of electro-Fenton and anodic oxidation processes.

PubMed

Feng, Ling; Oturan, Nihal; van Hullebusch, Eric D; Esposito, Giovanni; Oturan, Mehmet A

2014-01-01

The electrochemical degradation of the nonsteroidal anti-inflammatory drug ketoprofen in tap water has been studied using electro-Fenton (EF) and anodic oxidation (AO) processes with platinium (Pt) and boron-doped diamond (BDD) anodes and carbon felt cathode. Fast degradation of the parent drug molecule and its degradation intermediates leading to complete mineralization was achieved by BDD/carbon felt, Pt/carbon felt, and AO with BDD anode. The obtained results showed that oxidative degradation rate of ketoprofen and mineralization of its aqueous solution increased by increasing applied current. Degradation kinetics fitted well to a pseudo-first-order reaction. Absolute rate constant of the oxidation of ketoprofen by electrochemically generated hydroxyl radicals was determined to be (2.8 ± 0.1) × 10(9) M(-1) s(-1) by using competition kinetic method. Several reaction intermediates such as 3-hydroxybenzoic acid, pyrogallol, catechol, benzophenone, benzoic acid, and hydroquinone were identified by high-performance liquid chromatography (HPLC) analyses. The formation, identification, and evolution of short-chain aliphatic carboxylic acids like formic, acetic, oxalic, glycolic, and glyoxylic acids were monitored with ion exclusion chromatography. Based on the identified aromatic/cyclic intermediates and carboxylic acids as end products before mineralization, a plausible mineralization pathway was proposed. The evolution of the toxicity during treatments was also monitored using Microtox method, showing a faster detoxification with higher applied current values.

Real-Time In Vivo Monitoring of Reactive Oxygen Species in Guard Cells.

PubMed

Park, Ky Young; Roubelakis-Angelakis, Kalliopi A

2018-01-01

The intra-/intercellular homeostasis of reactive oxygen species (ROS), and especially of superoxides (O 2 .- ) and hydrogen peroxide (O 2 .- ) participate in signalling cascades which dictate developmental processes and reactions to biotic/abiotic stresses. Polyamine oxidases terminally oxidize/back convert polyamines generating H 2 O 2 . Recently, an NADPH-oxidase/Polyamine oxidase feedback loop was identified to control oxidative burst under salinity. Thus, the real-time localization/monitoring of ROS in specific cells, such as the guard cells, can be of great interest. Here we present a detailed description of the real-time in vivo monitoring of ROS in the guard cells using H 2 O 2 - and O 2 .- specific fluorescing probes, which can be used for studying ROS accumulation generated from any source, including the amine oxidases-dependent pathway, during development and stress.

Ultra-weak photon emission as a non-invasive tool for monitoring of oxidative processes in the epidermal cells of human skin: comparative study on the dorsal and the palm side of the hand.

PubMed

Rastogi, Anshu; Pospísil, Pavel

2010-08-01

All living organisms emit spontaneous ultra-weak photon emission as a result of cellular metabolic processes. Exposure of living organisms to exogenous factors results in oxidative processes and enhancement in ultra-weak photon emission. Here, hydrogen peroxide (H(2)O(2)), as a strongly oxidizing molecule, was used to induce oxidative processes and enhance ultra-weak photon emission in human hand skin. The presented work intends to compare both spontaneous and peroxide-induced ultra-weak photon emission from the epidermal cells on the dorsal and the palm side of the hand. A highly sensitive photomultiplier tube and a charge-coupled device camera were used to detect ultra-weak photon emission from human hand skin. Spontaneous ultra-weak photon emission from the epidermal cells on the dorsal side of the hand was 4 counts/s. Topical application of 500 mM H(2)O(2) to the dorsal side of the hand caused enhancement in ultra-weak photon emission to 40 counts/s. Interestingly, both spontaneous and peroxide-induced ultra-weak photon emission from the epidermal cells on the palm side of the hand were observed to increase twice their values, i.e. 8 and 80 counts/s, respectively. Similarly, the two-dimensional image of ultra-weak photon emission observed after topical application of H(2)O(2) to human skin reveals that photon emission from the palm side exceeds the photon emission from the dorsal side of the hand. The results presented indicate that the ultra-weak photon emission originating from the epidermal cells on the dorsal and the palm side of the hand is related to the histological structure of the human hand skin. Ultra-weak photon emission is shown as a non-destructive technique for monitoring of oxidative processes in the epidermal cells of the human hand skin and as a diagnostic tool for skin diseases.

Monitoring the nitrification and identifying the endpoint of ammonium oxidation by using a novel system of titrimetry.

PubMed

Zhang, Xin; Zhang, Daijun; Lu, Peili; Bai, Cui; Xiao, Pengying

2011-01-01

Based on the structure of the hybrid respirometer previously developed in our group, a novel implementation for titrimetry was developed, in which two pH electrodes were installed at the inlet and outlet of the measuring cell. The software capable of digital filtering and titration time delay correction was developed in LabVIEW. The hardware and software of the titrimeter and the respirometer were integrated to construct a novel system of respirometry-titrimetry. The system was applied to monitor a batch nitrification process. The obtained profiles of oxygen uptake rate (OUR) and hydrogen ion production rate (HPR) are consistent with each other and agree with the principle of the biological nitrification reaction. According to the OUR and HPR measurements, the oxidized ammonium concentrations were estimated accurately. Furthermore, the endpoint of ammonium oxidation was identified with much higher sensitivity by the HPR measurement. The system could be potentially used for on-line monitoring of biochemical reactions occurring in any kind of bioreactors because its measuring cell is completely independent of the bioreactor.

Analysis of oxidised heavy paraffininc products by high temperature comprehensive two-dimensional gas chromatography.

PubMed

Potgieter, H; Bekker, R; Beigley, J; Rohwer, E

2017-08-04

Heavy petroleum fractions are produced during crude and synthetic crude oil refining processes and they need to be upgraded to useable products to increase their market value. Usually these fractions are upgraded to fuel products by hydrocracking, hydroisomerization and hydrogenation processes. These fractions are also upgraded to other high value commercial products like lubricant oils and waxes by distillation, hydrogenation, and oxidation and/or blending. Oxidation of hydrogenated heavy paraffinic fractions produces high value products that contain a variety of oxygenates and the characterization of these heavy oxygenates is very important for the control of oxidation processes. Traditionally titrimetric procedures are used to monitor oxygenate formation, however, these titrimetric procedures are tedious and lack selectivity toward specific oxygenate classes in complex matrices. Comprehensive two-dimensional gas chromatography (GC×GC) is a way of increasing peak capacity for the comprehensive analysis of complex samples. Other groups have used HT-GC×GC to extend the carbon number range attainable by GC×GC and have optimised HT-GC×GC parameters for the separation of aromatics, nitrogen-containing compounds as well as sulphur-containing compounds in heavy petroleum fractions. HT-GC×GC column combinations for the separation of oxygenates in oxidised heavy paraffinic fractions are optimised in this study. The advantages of the HT-GC×GC method in the monitoring of the oxidation reactions of heavy paraffinic fraction samples are illustrated. Copyright © 2017 Elsevier B.V. All rights reserved.

Real-time combustion controls and diagnostics sensors (CCADS)

DOEpatents

Thornton, Jimmy D.; Richards, George A.; Dodrill, Keith A.; Nutter, Jr., Roy S.; Straub, Douglas

2005-05-03

The present invention is directed to an apparatus for the monitoring of the combustion process within a combustion system. The apparatus comprises; a combustion system, a means for supplying fuel and an oxidizer, a device for igniting the fuel and oxidizer in order to initiate combustion, and a sensor for determining the current conducted by the combustion process. The combustion system comprises a fuel nozzle and an outer shell attached to the combustion nozzle. The outer shell defines a combustion chamber. Preferably the nozzle is a lean premix fuel nozzle (LPN). Fuel and an oxidizer are provided to the fuel nozzle at separate rates. The fuel and oxidizer are ignited. A sensor positioned within the combustion system comprising at least two electrodes in spaced-apart relationship from one another. At least a portion of the combustion process or flame is between the first and second electrodes. A voltage is applied between the first and second electrodes and the magnitude of resulting current between the first and second electrodes is determined.

Redox Control of Asthma: Molecular Mechanisms and Therapeutic Opportunities

PubMed Central

Erzurum, Serpil C.

2010-01-01

Abstract An imbalance in reducing and oxidizing (redox) systems favoring a more oxidative environment is present in asthma and linked to the pathophysiology of the defining symptoms and signs including airflow limitation, hyper-reactivity, and airway remodeling. High levels of hydrogen peroxide, nitric oxide (•NO), and 15-F2t-isoprostane in exhaled breath, and excessive oxidative protein products in lung epithelial lining fluid, peripheral blood, and urine provide abundant evidence for pathologic oxidizing processes in asthma. Parallel studies document loss of reducing potential by nonenzymatic and enzymatic antioxidants. The essential first line antioxidant enzymes superoxide dismutases (SOD) and catalase are reduced in asthma as compared to healthy individuals, with lowest levels in those patients with the most severe asthma. Loss of SOD and catalase activity is related to oxidative modifications of the enzymes, while other antioxidant gene polymorphisms are linked to susceptibility to develop asthma. Monitoring of exhaled •NO has entered clinical practice because it is useful to optimize asthma care, and a wide array of other biochemical oxidative and nitrative biomarkers are currently being evaluated for asthma monitoring and phenotyping. Novel therapeutic strategies that target correction of redox abnormalities show promise for the treatment of asthma. Antioxid. Redox Signal. 12, 93–124. PMID:19634987

Periodic oxidation for fabricating titanium oxynitride thin films via atomic layer deposition

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

Iwashita, Shinya, E-mail: shinya.iwashita@tel.com; Aoyama, Shintaro; Nasu, Masayuki

2016-01-15

This paper demonstrates thermal atomic layer deposition (ALD) combined with periodic oxidation for synthesizing titanium oxynitride (TiON) thin films. The process used a typical ALD reactor for the synthesis of titanium nitride (TiN) films wherein oxygen was supplied periodically between the ALD-TiN cycles. The great advantage of the process proposed here was that it allowed the TiN films to be oxidized efficiently. Also, a uniform depth profile of the oxygen concentration in the films could be obtained by tuning the oxidation conditions, allowing the process to produce a wide variety of TiON films. The resistivity measurement is a convenient methodmore » to confirm the reproducibility of metal film fabrication but may not be applicable for TiON films depending upon the oxidation condition because the films can easily turn into insulators when subjected to periodic oxidation. Therefore, an alternative reproducibility confirmation method was required. In this study, spectroscopic ellipsometry was applied to monitor the variation of TiON films and was able to detect changes in film structures such as conductor–insulator transitions in the TiON films.« less

Development of a CO 2 Chemical Sensor for Downhole CO 2 Monitoring in Carbon Sequestration

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

Liu, Ning

Geologic storage of carbon dioxide (CO 2) has been proposed as a viable means for reducing anthropogenic CO 2 emissions. The means for geological sequestration of CO 2 is injection of supercritical CO 2 underground, which requires the CO 2 to remain either supercritical, or in solution in the water/brine present in the underground formation. However, there are aspects of geologic sequestration that need further study, particularly in regards to safety. To date, none of the geologic sequestration locations have been tested for storage integrity under the changing stress conditions that apply to the sequestration of very large amounts ofmore » CO 2. Establishing environmental safety and addressing public concerns require widespread monitoring of the process in the deep subsurface. In addition, studies of subsurface carbon sequestration such as flow simulations, models of underground reactions and transports require a comprehensive monitoring process to accurately characterize and understand the storage process. Real-time information about underground CO 2 movement and concentration change is highly helpful for: (1) better understanding the uncertainties present in CO 2 geologic storage; (2) improvement of simulation models; and (3) evaluation of the feasibility of geologic CO 2 storage. Current methods to monitor underground CO 2 storage include seismic, geoelectric, isotope and tracer methods, and fluid sampling analysis. However, these methods commonly resulted low resolution, high cost, and the inability to monitor continuously over the long time scales of the CO 2 storage process. A preferred way of monitoring in-situ underground CO 2 migration is to continuous measure CO 2 concentration change in brine during the carbon storage process. An approach to obtain the real time information on CO 2 concentration change in formation solution is highly demanded in carbon storage to understand the CO 2 migration subsurface and to answer the public safety problem. The objective of the study is to develop a downhole CO 2 sensor that can in-situ, continuously monitor CO 2 concentration change in deep saline. The sensor is a Severinghaus-type CO 2 sensor with small size, which renders it can be embedded in monitoring well casing or integrated with pressure/temperature transducers, enabling the development of “smart” wells. The studies included: (1) prepare and characterize metal-oxide electrodes. Test the electrodes response to pH change. Investigate different ions and brine concentration effects on the electrode’s performance. Study the stability of the electrode in brine solution; (2) fabricate a downhole CO 2 sensor with the metal-oxide electrodes prepared in the laboratory. Test the performance of the CO 2 sensor in brine solutions. Study high pressure effects on the performance of the sensor; (3) design and conduct CO 2/brine coreflooding experiments with the CO2 sensor. Monitor CO 2 movement along the core and test the performance of the sensor in coreflooding tests. Develop a data acquisition system that can digitize the sensor’s output voltage. Our completed research has resulted in deep understanding of downhole CO 2 sensor development and CO 2 monitoring in CO 2 storage process. The developed downhole CO 2 sensor included a metal-oxide electrode, a gas-permeable membrane, a porous steel cup, and a bicarbonate-based internal electrolyte solution. Iridium oxide-based electrode was prepared and used for preparation the CO 2 sensor. The prepared iridium oxide-based electrode displayed a linearly response to pH change. Different factors such as different ions and ions concentration, temperature, and pressure effects on the electrode performance on pH response were investigated. The results indicated that the electrode exhibited a good performance even in high salt concentration of produced water. To improve the electrode performance under high pressure, IrO 2 nanoparticles with the particle size in the range of 1-2 nm were prepared and electrodeposited on stainless steel substrate by cyclic voltammetry. It was observed that the thin film of iridium oxide was formed on the substrate surface and such iridium oxide-based electrode displayed excellent performance under high pressure for longer term. A downhole CO 2 sensor with the iridium oxide-based electrode was prepared. The working principle of the CO 2 sensor is based on the measurement of the pH change of the internal electrolyte solution caused by the hydrolysis of CO 2 and then determination of the CO 2 concentration in water. The prepared downhole CO 2 sensor had the size of diameter of 0.7 in. and length of 1.5 in. The sensor was tested under the pressures of 500 psi, 2,000 psi, and 3,000 psi. A linear correlation was observed between the sensor potential change and dissolved CO 2 concentration in water. The response time of the CO 2 sensor was in the range of 60-100 minutes. Further tests indicated that the CO 2 sensor exhibited good reproducibility under high pressure. A CO 2/brine coreflooding system was constructed to simulate the real-world CO 2 storage process. The prepared downhole CO 2 sensor was loaded in the system to monitor CO 2 movement during CO 2/brine coreflooding test. The results indicated that the sensor could detect CO 2 movement in the tests. Further studies showed that the sensor could be recovered by brine flooding after CO 2/brine flushed the core. The results of the coreflooding tests demonstrated that the sensor had potential application for CO 2 monitoring in carbon sequestration. A data acquisition system for the downhoe CO 2 sensor was developed and coded. The system converted the sensor output signal into digital data and transported the data from downhole to wellhead surface. The data acquisition system was tested and evaluated in the laboratory with the prepared sensor for data collection.« less

40 CFR Table 1 to Subpart Hhhh of... - Minimum Requirements for Monitoring and Recordkeeping

Code of Federal Regulations, 2010 CFR

2010-07-01

...-hour block averages. 2. Other process or control device parameters specified in your OMM b plan. As... value for each product manufactured during the operating day. 6. UF-to-latex ratio in the binder c For... Required if a thermal oxidizer is used to control formaldehyde emissions. b Required if process...

Tetramethylbenzidine method for monitoring the free available chlorine and microbicidal activity of chlorite-based sanitizers under organic-matter-rich environments.

PubMed

Yamaoka, H; Nakayama-Imaohji, H; Horiuchi, I; Yamasaki, H; Nagao, T; Fujita, Y; Maeda, H; Goda, H; Kuwahara, T

2016-01-01

Chlorine is a principal disinfectant for food and environmental sanitation. Monitoring of free available chlorine (FAC) is essential for ensuring the efficacy of food disinfection processes that rely on chlorine. N,N-diethyl-p-phenylenediamine (DPD) is commonly used for FAC monitoring. However, here, we show that upon contact with bovine serum albumin (BSA) or broiler carcasses, chlorite (HClO2 )-based sanitizers acquire a pink colour, which can interfere with measurement of oxidized DPD absorbance at 513-550 nm. Alternatively, the pink colour did not interfere with 3,3',5,5'-tetramethylbenzidine (TMB)-based FAC monitoring. The FAC levels of NaClO and weakly acidified chlorous acid water (WACAW) were first adjusted by the TMB method and the killing activity of these sanitizers towards methicillin-resistant Staphylococcus aureus (MRSA) and feline calicivirus (FCV) was compared in the presence or absence of 0·5% BSA. At 200 ppm FAC, NaClO lost its bactericidal activity against MRSA after 10-min incubation with 0·5% BSA. Meanwhile, under the same conditions WACAW reduced the number of bacteria to below the detection limit. Similar results were obtained with FCV, indicating that the chlorite-based WACAW sanitizer is relatively stable under organic-matter-rich conditions. Moreover, TMB is suitable for in situ FAC monitoring of chlorite-based sanitizers in food and environmental disinfection processes. For practical applications of chlorine in food processing, monitoring of FAC is critical to validate disinfection efficacy. In this study we found that chlorite-based sanitizers acquired a pink colour upon contact with BSA or broiler carcasses. This pink colour interfered with FAC monitoring by methods that measure oxidized N,N-diethyl-p-phenylenediamine absorbance between 513-550 nm. Alternatively, FAC levels of chlorite-based sanitizers could be monitored using the absorbance of 3,3',5,5'-tetramethylbenzidine at 650 nm, which does not overlap with the acquired pink colour. These data provide valuable information for safety management of disinfection processes that use chlorite-based sanitizers. © 2015 The Society for Applied Microbiology.

Special Advanced Studies for Pollution Prevention. Delivery Order 0065: The Monitor - Spring 2001

DTIC Science & Technology

2001-06-01

coating) baths by remov- ing trace contaminant metals as well as restoring and maintaining the hexavalent chromium or ferric species. The oxidizing...power for the process acid is restored by oxidation (trivalent chromium to hexavalent chromium or ferrous to ferric) at the anode. Other sources of...selection to the application. UF membranes are suitable for particles in the molecular range of 0.1-0.01microns. Microfiltration membranes are similar

40 CFR 63.3557 - What are the requirements for continuous parameter monitoring system installation, operation, and...

Code of Federal Regulations, 2010 CFR

2010-07-01

... (ii) of this section for each gas temperature monitoring device. (i) Locate the temperature sensor in... oxidizer, install a gas temperature monitor in the firebox of the thermal oxidizer or in the duct... oxidizer, install a gas temperature monitor according to paragraph (c)(2)(i) or (ii) of this section. (i...

40 CFR 63.4967 - What are the requirements for continuous parameter monitoring system installation, operation, and...

Code of Federal Regulations, 2011 CFR

2011-07-01

... section for each gas temperature monitoring device. (i) Locate the temperature sensor in a position that... oxidizer, install a gas temperature monitor in the firebox of the thermal oxidizer or in the duct... oxidizer, install a gas temperature monitor in the gas stream immediately before the catalyst bed, and if...

40 CFR 63.4967 - What are the requirements for continuous parameter monitoring system installation, operation, and...

Code of Federal Regulations, 2010 CFR

2010-07-01

... section for each gas temperature monitoring device. (i) Locate the temperature sensor in a position that... oxidizer, install a gas temperature monitor in the firebox of the thermal oxidizer or in the duct... oxidizer, install a gas temperature monitor in the gas stream immediately before the catalyst bed, and if...

40 CFR 63.3557 - What are the requirements for continuous parameter monitoring system installation, operation, and...

Code of Federal Regulations, 2011 CFR

2011-07-01

... (ii) of this section for each gas temperature monitoring device. (i) Locate the temperature sensor in... oxidizer, install a gas temperature monitor in the firebox of the thermal oxidizer or in the duct... oxidizer, install a gas temperature monitor according to paragraph (c)(2)(i) or (ii) of this section. (i...

Pilot scale application of nanosized iron oxides as electron acceptors for bioremediation

NASA Astrophysics Data System (ADS)

Bosch, Julian; Fritzsche, Andreas; Frank-Fahle, Beatrice; Lüders, Tilmann; Höss, Sebastian; Eisenmann, Heinrich; Held, Thomas; Totsche, Kai U.; Meckenstock, Rainer U.

2014-05-01

Microbial reduction of ferric iron is a major biogeochemical process in groundwater aquifer ecosystems and often associated with the degradation of organic contaminants, as bacteria couple iron reduction to the oxidation reduced carbon like e.g. BTEX. Yet in general the low bioavailability of natural iron oxides limits microbial reduction rates. However, nanosized iron oxides have an unequally enhanced bioavailability and reactivity compared to their respective bulk, macro-sized, and more crystalline materials. At the same time, nanosized iron oxides can be produced in stable colloidal suspensions, permitting efficient injections into contaminated aquifers. We examined the reactivity of nanosized synthetic colloidal iron oxides in microbial iron reduction. Application of colloidal nanoparticles led to a strong and sustainable enhancement of microbial reaction rates in batch experiments and sediment columns. Toluene oxidation was increased five-fold as compared to bulk, non-colloidal ferrihydrite as electron acceptor. Furthermore, we developed a unique approach for custom-tailoring the subsurface mobility of these particles after being injected into a contaminant plume. In a field pilot application, we injected 18 m3 of an iron oxide nanoparticle solution into a BTEX contaminated aquifer with a maximum excess pressure as low as 0.2 bar. The applied suspension showed a superior subsurface mobility, creating a reactive zone of 4 m height (corresponding to the height of the confined aquifer) and 6 m in diameter. Subsequent monitoring of BTEX, microbial BTEX degradation metabolites, ferrous iron generation, stable isotopes fractionation, microbial populations, and methanogenesis demonstrated the strong impact of our approach. Mathematic processed X-ray diffractograms and FTIR spectra provided a semi-quantitatively estimate of the long-term fate of the iron oxide colloids in the aquifer. Potential environmental risks of the injection itself were monitored with ecotoxicological investigations. Our data suggest that the injection of ferric iron nanoparticles as electron acceptors into contaminated aquifers for the enhancement of microbial contaminant degradation might develop into a novel bioremediation strategy.

A novel squarylium dye for monitoring oxidative processes in lipid membranes.

PubMed

Trusova, Valeriya M; Gorbenko, Galyna P; Deligeorgiev, Todor; Gadjev, Nikolai; Vasilev, Aleksey

2009-11-01

A novel squaraine probe SQ-1 has been found to be appropriate for monitoring the peroxidation processes in membrane systems. Formation of free radicals was triggered by methemoglobin (metHb) or cytochrome c (cyt c) binding to the model lipid membranes composed of zwitterionic lipid phosphatidylcholine (PC) and anionic lipid cardiolipin (CL). Protein association with the lipid vesicles was followed by drastic quenching of SQ-1 fluorescence. The observed spectral changes were suppressed in the presence of free radical scavengers, butylated hydroxytoluene (BHT) and thiourea (TM) suggesting that SQ-1 decolorization can be attributed to its reactions with lipid radicals.

Real-time thermal imaging of solid oxide fuel cell cathode activity in working condition.

PubMed

Montanini, Roberto; Quattrocchi, Antonino; Piccolo, Sebastiano A; Amato, Alessandra; Trocino, Stefano; Zignani, Sabrina C; Faro, Massimiliano Lo; Squadrito, Gaetano

2016-09-01

Electrochemical methods such as voltammetry and electrochemical impedance spectroscopy are effective for quantifying solid oxide fuel cell (SOFC) operational performance, but not for identifying and monitoring the chemical processes that occur on the electrodes' surface, which are thought to be strictly related to the SOFCs' efficiency. Because of their high operating temperature, mechanical failure or cathode delamination is a common shortcoming of SOFCs that severely affects their reliability. Infrared thermography may provide a powerful tool for probing in situ SOFC electrode processes and the materials' structural integrity, but, due to the typical design of pellet-type cells, a complete optical access to the electrode surface is usually prevented. In this paper, a specially designed SOFC is introduced, which allows temperature distribution to be measured over all the cathode area while still preserving the electrochemical performance of the device. Infrared images recorded under different working conditions are then processed by means of a dedicated image processing algorithm for quantitative data analysis. Results reported in the paper highlight the effectiveness of infrared thermal imaging in detecting the onset of cell failure during normal operation and in monitoring cathode activity when the cell is fed with different types of fuels.

Furan in Thermally Processed Foods - A Review

PubMed Central

Seok, Yun-Jeong; Her, Jae-Young; Kim, Yong-Gun; Kim, Min Yeop; Jeong, Soo Young; Kim, Mina K.; Lee, Jee-yeon; Kim, Cho-il; Yoon, Hae-Jung

2015-01-01

Furan (C4H4O) is a volatile compound formed mostly during the thermal processing of foods. The toxicity of furan has been well documented previously, and it was classified as “possible human carcinogen (Group 2B)” by the International Agency for Research on Cancer. Various pathways have been reported for the formation of furan, that is, thermal degradation and/or thermal rearrangement of carbohydrates in the presence of amino acids, thermal degradation of certain amino acids, including aspartic acid, threonine, α-alanine, serine, and cysteine, oxidation of ascorbic acid at higher temperatures, and oxidation of polyunsaturated fatty acids and carotenoids. Owing to the complexity of the formation mechanism, a vast number of studies have been published on monitoring furan in commercial food products and on the potential strategies for reducing furan. Thus, we present a comprehensive review on the current status of commercial food monitoring databases and the possible furan reduction methods. Additionally, we review analytical methods for furan detection and the toxicity of furan. PMID:26483883

Real-time combustion control and diagnostics sensor-pressure oscillation monitor

DOEpatents

Chorpening, Benjamin T [Morgantown, WV; Thornton, Jimmy [Morgantown, WV; Huckaby, E David [Morgantown, WV; Richards, George A [Morgantown, WV

2009-07-14

An apparatus and method for monitoring and controlling the combustion process in a combustion system to determine the amplitude and/or frequencies of dynamic pressure oscillations during combustion. An electrode in communication with the combustion system senses hydrocarbon ions and/or electrons produced by the combustion process and calibration apparatus calibrates the relationship between the standard deviation of the current in the electrode and the amplitudes of the dynamic pressure oscillations by applying a substantially constant voltage between the electrode and ground resulting in a current in the electrode and by varying one or more of (1) the flow rate of the fuel, (2) the flow rate of the oxidant, (3) the equivalence ratio, (4) the acoustic tuning of the combustion system, and (5) the fuel distribution in the combustion chamber such that the amplitudes of the dynamic pressure oscillations in the combustion chamber are calculated as a function of the standard deviation of the electrode current. Thereafter, the supply of fuel and/or oxidant is varied to modify the dynamic pressure oscillations.

Vectorial method used to monitor an evolving system: Titanium oxide thin films under UV illumination

NASA Astrophysics Data System (ADS)

Béchu, Solène; Humbert, Bernard; Fernandez, Vincent; Fairley, Neal; Richard-Plouet, Mireille

2018-07-01

Under in situ UV illumination, some materials present evolution of their opto-electronic properties that can be monitored by spectroscopy. We present here a mathematical method which can be applied to spectroscopic measurements when an evolving set of data is recorded: the vectorial method. The investigations and quantifications are performed by Infrared spectroscopy and XPS on organic-inorganic thin films prepared by sol-gel. The inorganic part of these hybrid thin films contains Ti oxide-network based whereas the organic part is composed of N,N-dimethylformamide and its hydrolysis products. Under UV illumination, those films exhibit intermediate bandgap behavior due to the photoreduction of Ti(IV) in Ti(III). The role of the solvent in the thin film is underlined during the process of photoreduction together with an understanding of the condensation of the Ti oxide-based network, as these evolutions are critical for the opto-electronic properties of those thin films.

Reduction Dynamics of Doped Ceria, Nickel Oxide, and Cermet Composites Probed Using In Situ Raman Spectroscopy

PubMed Central

Shearing, Paul R.; Brightman, Edward; Brett, Dan J. L.; Brandon, Nigel P.; Cohen, Lesley F.

2016-01-01

The redox properties of gadolinium doped ceria (CGO) and nickel oxide (NiO) composite cermets underpin the operation of solid oxide electrochemical cells. Although these systems have been widely studied, a full comprehension of the reaction dynamics at the interface of these materials is lacking. Here, in situ Raman spectroscopic monitoring of the redox cycle is used to investigate the interplay between the dynamic and competing processes of hydrogen spillover and water dissociation on the doped ceria surface. In order to elucidate these mechanisms, the redox process in pure CGO and NiO is studied when exposed to wet and dry hydrogen and is compared to the cermet behavior. In dry hydrogen, CGO reduces relatively rapidly via a series of intermediate phases, while NiO reduces via a single‐step process. In wet reducing atmospheres, however, the oxidation state of pure CGO is initially stabilized due to the dissociation of water by reduced Ce(III) and subsequent incorporation of oxygen into the structure. In the reduction process involving the composite cermet, the close proximity of the NiO improves the efficiency and speed of the composite reduction process. Although NiO is already incorporated into working cells, these observations suggest direct routes to further improve cell performance. PMID:27595058

Reduction Dynamics of Doped Ceria, Nickel Oxide, and Cermet Composites Probed Using In Situ Raman Spectroscopy.

PubMed

Maher, Robert C; Shearing, Paul R; Brightman, Edward; Brett, Dan J L; Brandon, Nigel P; Cohen, Lesley F

2016-01-01

The redox properties of gadolinium doped ceria (CGO) and nickel oxide (NiO) composite cermets underpin the operation of solid oxide electrochemical cells. Although these systems have been widely studied, a full comprehension of the reaction dynamics at the interface of these materials is lacking. Here, in situ Raman spectroscopic monitoring of the redox cycle is used to investigate the interplay between the dynamic and competing processes of hydrogen spillover and water dissociation on the doped ceria surface. In order to elucidate these mechanisms, the redox process in pure CGO and NiO is studied when exposed to wet and dry hydrogen and is compared to the cermet behavior. In dry hydrogen, CGO reduces relatively rapidly via a series of intermediate phases, while NiO reduces via a single-step process. In wet reducing atmospheres, however, the oxidation state of pure CGO is initially stabilized due to the dissociation of water by reduced Ce(III) and subsequent incorporation of oxygen into the structure. In the reduction process involving the composite cermet, the close proximity of the NiO improves the efficiency and speed of the composite reduction process. Although NiO is already incorporated into working cells, these observations suggest direct routes to further improve cell performance.

40 CFR 63.3968 - What are the requirements for continuous parameter monitoring system installation, operation, and...

Code of Federal Regulations, 2011 CFR

2011-07-01

...: (1) For a thermal oxidizer, install a gas temperature monitor in the firebox of the thermal oxidizer...) For a catalytic oxidizer, install gas temperature monitors upstream and/or downstream of the catalyst... the requirements in paragraphs (a) and (c)(3)(i) through (v) of this section for each gas temperature...

40 CFR 63.3968 - What are the requirements for continuous parameter monitoring system installation, operation, and...

Code of Federal Regulations, 2010 CFR

2010-07-01

...: (1) For a thermal oxidizer, install a gas temperature monitor in the firebox of the thermal oxidizer...) For a catalytic oxidizer, install gas temperature monitors upstream and/or downstream of the catalyst... the requirements in paragraphs (a) and (c)(3)(i) through (v) of this section for each gas temperature...

Studies of protein oxidation as a product quality attribute on a scale-down model for cell culture process development.

PubMed

Lee, Nacole D; Kondragunta, Bhargavi; Uplekar, Shaunak; Vallejos, Jose; Moreira, Antonio; Rao, Govind

2015-01-01

Of importance to the biological properties of proteins produced in cell culture systems are the complex post-translational modifications that are affected by variations in process conditions. Protein oxidation, oxidative modification to intracellular proteins that involves cleavage of the polypeptide chain, and modifications of the amino acid side chains can be affected by such process variations. Dissolved oxygen is a parameter of increasing interest since studies have shown that despite the necessity of oxygen for respiration, there may also be some detrimental effects of oxygen to the cell. Production and accumulation of reactive oxygen species can cause damage to proteins as a result of oxidation of the cell and cellular components. Variation, or changes to cell culture products, can affect function, clearance rate, immunogenicity, and specific activity, which translates into clinical implications. The effect of increasing dissolved oxygen on protein oxidation in immunoglobulin G3-producing mouse hybridoma cells was studied using 50 mL high-throughput mini-bioreactors that employ non-invasive optical sensor technology for monitoring and closed feedback control of pH and dissolved oxygen. Relative protein carbonyl concentration of proteins produced under varying levels of dissolved oxygen was measured by enzyme-linked immunosorbent assay and used as an indicator of oxidative damage. A trend of increasing protein carbonyl content in response to increasing dissolved oxygen levels under controlled conditions was observed. Protein oxidation, oxidative modification to intracellular proteins that involves cleavage of the polypeptide chain, and modifications of the amino acid side chains can be affected by variations in dissolved oxygen levels in cell culture systems. Studies have shown that despite the necessity of oxygen for respiration, there may be detrimental effects of oxygen to the cell. Production and accumulation of reactive oxygen species can cause damage to proteins as a result of oxidation of the cell and cellular components, affecting function, clearance rate, immunogenicity, and specific activity, which translates into clinical implications. The effect of increasing dissolved oxygen on protein oxidation in immunoglobulin G3-producing mouse hybridoma cells was studied using 50 mL high-throughput mini-bioreactors that employ non-invasive optical sensor technology for monitoring and closed feedback control of pH and dissolved oxygen. Protein carbonyl concentration of proteins produced under varying levels of dissolved oxygen was measured by enzyme-linked immunosorbent assay and used as an indicator of oxidative damage. A trend of increasing protein carbonyl content in response to increasing dissolved oxygen levels under controlled conditions was observed. © PDA, Inc. 2015.

Oxidation and hot corrosion of hot-pressed Si3N4 at 1000 deg C

NASA Technical Reports Server (NTRS)

Fielder, W. L.

1985-01-01

The oxidation and hot corrosion of a commercial, hot-pressed Si3N4 were investigated at 1000 C under an atmosphere of flowing O2. For the hot corrosion studies, thin films of Na2SO4 were airbrushed on the Si3N4 surface. The hot corrosion attack was monitored by the following techniques: continuous weight measurements, SO2 evolution, film morphology, and chemical analyses. Even though the hot corrosion weight changes after 25 hr were relatively small, the formation of SiO2 from oxidation of Si3N4 was an order of magnitude greater in the presence of molten Na2SO4. The formation of a protective SiO2 phase at the Si3N4 surface is minimized by the fluxing action of the molten Na2SO4 thereby allowing the oxidation of the Si3N4 to proceed more rapidly. A simple process is proposed to account for the hot corrosion process.

Re-evaluation of Moisture Controls During ARIES Oxide Processing, Packaging and Characterization

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

Karmiol, Benjamin; Wayne, David Matthew

DOE-STD-3013 [1] requires limiting the relative humidity (RH) in the glovebox during processing of the oxide product for specific types of plutonium oxides. This requirement is mandated in order to limit corrosion of the stainless steel containers by deliquescence of chloride salts if present in the PuO2. DOE-STD-3013 also specifies the need to limit and monitor internal pressure buildup in the 3013 containers due to the potential for the generation of free H2 and O2 gas from the radiolysis of surfaceadsorbed water. DOE-STD-3013 requires that the oxide sample taken for moisture content verification be representative of the stabilized material inmore » the 3013 container. This is accomplished by either limiting the time between sampling and packaging, or by control of the glovebox relative humidity (%RH). This requirement ensures that the sample is not only representative, but also conservative from the standpoint of moisture content.« less

Study of ultrasonic cavitation during extraction of the peanut oil at varying frequencies.

PubMed

Zhang, Lei; Zhou, Cunshan; Wang, Bei; Yagoub, Abu El-Gasim A; Ma, Haile; Zhang, Xiao; Wu, Mian

2017-07-01

The ultrasonic extraction of oils is a typical physical processing technology. The extraction process was monitored from the standpoint of the oil quality and efficiency of oil extraction. In this study, the ultrasonic cavitation fields were measured by polyvinylidene fluoride (PVDF) sensor. Waveform of ultrasonic cavitation fields was gained and analyzed. The extraction yield and oxidation properties were compared. The relationship between the fields and cavitation oxidation was established. Numerical calculation of oscillation cycle was done for the cavitation bubbles. Results showed that the resonance frequency, f r , of the oil extraction was 40kHz. At f r , the voltage amplitude was the highest; the time was the shortest as reaching the amplitude of the waveform. Accordingly, the cavitation effect worked most rapidly, resulting in the strongest cavitation intensity. The extraction yield and oxidation properties were closely related to the cavitation effect. It controlled the cavitation oxidation effectively from the viewpoint of chemical and physical aspects. Copyright © 2017 Elsevier B.V. All rights reserved.

In Situ Infrared Spectroscopic Studies of Molecular Layer Deposition and Atomic Layer Etching Processes

NASA Astrophysics Data System (ADS)

DuMont, Jaime Willadean

In this thesis, in situ Fourier transform infrared (FTIR) spectroscopy was used to study: i) the growth and pyrolysis of molecular layer deposition (MLD) films. ii) the surface chemistry of atomic layer etching (ALE) processes. Atomic layer processes such as molecular layer deposition (MLD) and atomic layer etching (ALE) are techniques that can add or remove material with atomic level precision using sequential, self-limiting surface reactions. Deposition and removal processes at the atomic scale are powerful tools for many industrial and research applications such as energy storage and semiconductor nanofabrication. The first section of this thesis describes the chemistry of reactions leading to the MLD of aluminum and tin alkoxide polymer films known as "alucone" and "tincone", respectively. The subsequent pyrolysis of these films to produce metal oxide/carbon composites was also investigated. In situ FTIR spectroscopy was conducted to monitor surface species during MLD film growth and to monitor the films background infrared absorbance versus pyrolysis temperature. Ex situ techniques such as transmission electron microscopy (TEM), four-point probe and X-ray diffraction (XRD) were utilized to study the properties of the films post-pyrolysis. TEM confirmed that the pyrolyzed films maintained conformality during post-processing. Four-point probe monitored film resistivity versus pyrolysis temperature and XRD determined the film crystallinity. The second section of this thesis focuses on the surface chemistry of Al2O3 and SiO2 ALE processes, respectively. Thermal ALE processes have been recently developed which utilize sequential fluorination and ligand exchange reactions. An intimate knowledge of the surface chemistry is important in understanding the ALE process. In this section, the competition between the Al2O3 etching and AlF 3 growth that occur during sequential HF (fluorinating agent) and TMA (ligand exchange) exposures is investigated using in situ FTIR spectroscopy. Also included in this section is the first demonstration of thermal ALE for SiO2. In situ FTIR spectroscopy was conducted to monitor the loss of bulk Si-O vibrational modes corresponding to the removal of SiO2. FTIR was also used to monitor surface species during each ALE half cycle and to verify self-limiting behavior. X-ray reflectivity experiments were conducted to establish etch rates on thermal oxide silicon wafers.

The Role of Microbial Processes in the Oxidation and Removal of Ammonia from Drinking Water

EPA Science Inventory

The purpose of this study was two-fold: (1) to monitor and evaluate nitrification in a full-scale iron removal filtration plant with biologically active granular media filters located in Ohio, and (2) to determine how to most efficiently regain nitrification following filter rebe...

Synthesis of Diopside by Solution Combustion Process Using Glycine Fuel

NASA Astrophysics Data System (ADS)

Sherikar, Baburao N.; Umarji, A. M.

Nano ceramic Diopside (CaMgSi2O6) powders are synthesized by Solution Combustion Process(SCS) using Calcium nitrate, Magnesium nitrate as oxidizer and glycine as fuel, fumed silica as silica source. Ammonium nitrate (AN) is used as extra oxidizer. Effect of AN on Diopside phase formation is investigated. The adiabatic flame temperatures are calculated theoretically for varying amount of AN according to thermodynamic concept and correlated with the observed flame temperatures. A “Multi channel thermocouple setup connected to computer interfaced Keithley multi voltmeter 2700” is used to monitor the thermal events during the process. An interpretation based on maximum combustion temperature and the amount of gases produced during reaction for various AN compositions has been proposed for the nature of combustion and its correlation with the characteristics of as synthesized powder. These powders are characterized by XRD, SEM showing that the powders are composed of polycrystalline oxides with crystallite size of 58nm to 74nm.

Surfactant-assisted hollowing of Cu nanoparticles involving halide-induced corrosion-oxidation processes.

PubMed

Huang, Chih-Chia; Hwu, Jih Ru; Su, Wu-Chou; Shieh, Dar-Bin; Tzeng, Yonhua; Yeh, Chen-Sheng

2006-05-03

We have demonstrated a simple fabrication of hollow nanoparticles by halide-induced corrosion oxidation with the aid of surfactants. Cuprous oxide Cu2O nanoshells can be generated by simply mixing Cu nanoparticles with alkyltrimethylammonium halides at 55 degrees C for 16 min. The hollowing mechanism proposed is that absorption of surfactants onto the Cu surface facilitates the formation of the void interior through an oxidative etching process. Upon extending the reaction up to 4 h, fragmentation, oxidation, and self-assembly were observed and the CuO ellipsoidal structures were formed. The headgroup lengths of the surfactants influenced the degree of CuO ellipsoidal formation, whereby longer surfactants favored the generation of ellipsoids. Optical absorption measured by UV-visible spectroscopy was used to monitor both oxidation courses of Cu-->Cu2O and Cu2O-->CuO and to determine the band-gap energies as 2.4 eV for Cu2O nanoshells and 1.89 eV for CuO ellipsoids. For the contact-angle measurements, the wettability changed from hydrophilicity (18 degrees) to hydrophobicity (140 degrees) as the Cu2O nanoshells shifted to CuO ellipsoids.

Monitoring the Reaction Process During the S2 → S3 Transition in Photosynthetic Water Oxidation Using Time-Resolved Infrared Spectroscopy.

PubMed

Sakamoto, Hiroki; Shimizu, Tatsuki; Nagao, Ryo; Noguchi, Takumi

2017-02-08

Photosynthetic water oxidation performed at the Mn 4 CaO 5 cluster in photosystem II plays a crucial role in energy production as electron and proton sources necessary for CO 2 fixation. Molecular oxygen, a byproduct, is a source of the oxygenic atmosphere that sustains life on earth. However, the molecular mechanism of water oxidation is not yet well-understood. In the reaction cycle of intermediates called S states, the S 2 → S 3 transition is particularly important; it consists of multiple processes of electron transfer, proton release, and water insertion, and generates an intermediate leading to O-O bond formation. In this study, we monitored the reaction process during the S 2 → S 3 transition using time-resolved infrared spectroscopy to clarify its molecular mechanism. A change in the hydrogen-bond interaction of the oxidized Y Z • radical, an immediate electron acceptor of the Mn 4 CaO 5 cluster, was clearly observed as a ∼100 μs phase before the electron-transfer phase with a time constant of ∼350 μs. This observation provides strong experimental evidence that rearrangement of the hydrogen-bond network around Y Z • , possibly due to the movement of a water molecule located near Y Z • to the Mn site, takes place before the electron transfer. The electron transfer was coupled with proton release, as revealed by a relatively high deuterium kinetic isotope effect of 1.9. This proton release, which decreases the redox potential of the Mn 4 CaO 5 cluster to facilitate electron transfer to Y Z • , was proposed to determine, as a rate-limiting step, the relatively slow electron-transfer rate of the S 2 → S 3 transition.

Investigation into the role of NaCL deposited on oxide and metal substrates in the initiation of hot corrosion

NASA Technical Reports Server (NTRS)

Birks, N.

1981-01-01

The conversion to Na2SO4 of NaCl deposited on oxide substrates was studied as a function of temperature, in air with various SO2 and H2O partial pressures. The substrate was either a pure oxide or an oxide scale growing on a metal specimen. The progress of the reaction was observed using the SEM-EDAX technique to monitor morphological effects and, as far as possible, establish the rate of the process. The physical characteristics of the interaction between salt and substrate were also examined with particular reference to physical damage to the underlying oxide, especially when this is a scale on a metal specimen. An effort was also made to establish the conditions under which liquid phases may form and the mechanisms by which they form.

A cerium oxide nanoparticle-based device for the detection of chronic inflammation via optical and magnetic resonance imaging

NASA Astrophysics Data System (ADS)

Kaittanis, Charalambos; Santra, Santimukul; Asati, Atul; Perez, J. Manuel

2012-03-01

Monitoring of microenvironmental parameters is critical in healthcare and disease management. Harnessing the antioxidant activity of nanoceria and the imaging capabilities of iron oxide nanoparticles in a device setup, we were able to image changes in the device's aqueous milieu. The device was able to convey and process changes in the microenvironment's pH and reactive oxygen species' concentration, distinguishing physiological from abnormal levels. As a result under physiological and transient inflammatory conditions, the device's fluorescence and magnetic resonance signals, emanating from multimodal iron oxide nanoparticles, were similar. However, under chronic inflammatory conditions that are usually associated with high local concentrations of reactive oxygen species and pH decrease, the device's output was considerably different. Specifically, the device's fluorescence emission significantly decreased, while the magnetic resonance signal T2 increased. Further studies identified that the changes in the device's output are attributed to inactivation of the sensing component's nanoceria that prevents it from successfully scavenging the generated free radicals. Interestingly, the buildup of free radical excess led to polymerization of the iron oxide nanoparticle's coating, with concomitant formation of micron size aggregates. Our studies indicate that a nanoceria-based device can be utilized for the monitoring of pro-inflammatory biomarkers, having important applications in the management of numerous ailments while eliminating nanoparticle toxicity issues.Monitoring of microenvironmental parameters is critical in healthcare and disease management. Harnessing the antioxidant activity of nanoceria and the imaging capabilities of iron oxide nanoparticles in a device setup, we were able to image changes in the device's aqueous milieu. The device was able to convey and process changes in the microenvironment's pH and reactive oxygen species' concentration, distinguishing physiological from abnormal levels. As a result under physiological and transient inflammatory conditions, the device's fluorescence and magnetic resonance signals, emanating from multimodal iron oxide nanoparticles, were similar. However, under chronic inflammatory conditions that are usually associated with high local concentrations of reactive oxygen species and pH decrease, the device's output was considerably different. Specifically, the device's fluorescence emission significantly decreased, while the magnetic resonance signal T2 increased. Further studies identified that the changes in the device's output are attributed to inactivation of the sensing component's nanoceria that prevents it from successfully scavenging the generated free radicals. Interestingly, the buildup of free radical excess led to polymerization of the iron oxide nanoparticle's coating, with concomitant formation of micron size aggregates. Our studies indicate that a nanoceria-based device can be utilized for the monitoring of pro-inflammatory biomarkers, having important applications in the management of numerous ailments while eliminating nanoparticle toxicity issues. Electronic supplementary information (ESI) available: ESI figures. See DOI: 10.1039/c2nr11956k

The Application of Multiple Reaction Monitoring to Assess Apo A-I Methionine Oxidations in Diabetes and Cardiovascular Disease

PubMed Central

Yassine, Hussein N.; Jackson, Angela M.; Reaven, Peter D.; Nedelkov, Dobrin; Nelson, Randall W.; Lau, Serrine S.; Borchers, Christoph H.

2014-01-01

The oxidative modification of apolipoprotein A-I ‘s methionine148(M148) is associated with defective HDL function in vitro. Multiple Reaction Monitoring (MRM) is a mass spectrometric technique that can be used to quantitate post-translational modifications. In this study, we developed an MRM assay to monitor the abundance ratio of the peptide containing oxidized M148 to the native peptide in Apo A-I. Measurement of the oxidized-to-unoxidized-M148 ratio was reproducible (CV<5%). The extent of methionine M148 oxidation in the HDL of healthy controls, and type 2 diabetic participants with and without prior cardiovascular events (CVD) were then examined. The results suggest a significant increase in the relative ratio of the peptide containing oxidized M148 to the unmodified peptide in the HDL of participants with diabetes and CVD (p<0.001), compared to participants without CVD. Monitoring the abundance ratio of the peptides containing oxidized and unoxidized M148 by MRM provides a means of examining the relationship between M148 oxidation and vascular complications in CVD. PMID:25705587

Development of an IrO x micro pH sensor array on flexible polymer substrate

NASA Astrophysics Data System (ADS)

Huang, Wen-Ding; Wang, Jianqun; Ativanichayaphong, Thermpon; Chiao, Mu; Chiao, J. C.

2008-03-01

pH sensor is an essential component used in many chemical, food, and bio-material industries. Conventional glass electrodes have been used to construct pH sensors, however, have some disadvantages in specific applications. It is difficult to use glass electrodes for in vivo biomedical or food monitoring applications due to size limitation and no deformability. In this paper, we present design and fabrication processes of a miniature iridium oxide thin film pH sensor array on flexible polymer substrates. The amorphous iridium oxide thin film was used as the sensing material. A sol-gel dip-coating process of iridium oxide film was demonstrated in this paper. A super-Nernstian response has been measured on individual sensors of the array with a slope of -71.6+/-3 mV/pH at 25°C within the pH range between 2.83 and 11.04.

Analysis of the Material Removal Rate in Magnetic Abrasive Finishing of Thin Film Coated Pyrex Glass

NASA Astrophysics Data System (ADS)

Lee, Hee Hwan; Lee, Seoung Hwan

The material removal rate (MRR) during precision finishing/polishing is a key factor, which dictates the process performance. Moreover, the MRR or wear rate is closely related to the material/part reliability. For nanoscale patterning and/or planarization on nano-order thickness coatings, the prediction and in-process monitoring of the MRR is necessary, because the process is not characterizable due to size effects and material property/process condition variations as a result of the coating/substrate interactions. The purpose of this research was to develop a practical methodology for the prediction and in-process monitoring of MRR during nanoscale finishing of coated surfaces. Using a specially designed magnetic abrasive finishing (MAF) and acoustic emission (AE) monitoring setup, experiments were carried out on indium-zinc-oxide (IZO) coated Pyrex glasses. After a given polishing time interval, AFM indentation was conducted for each workpiece sample to measure the adhesion force variations of the coating layers (IZO), which are directly related to the MRR changes. The force variation and AE monitoring data were compared to the MRR calculated form the surface measurement (Nanoview) results. The experimental results demonstrate strong correlations between AFM indentation and MRR measurement data. In addition, the monitored AE signals show sensitivity of the material structure variations of the coating layer, as the polishing progresses.

Technology review: prototyping platforms for monitoring ambient conditions.

PubMed

Afolaranmi, Samuel Olaiya; Ramis Ferrer, Borja; Martinez Lastra, Jose Luis

2018-05-08

The monitoring of ambient conditions in indoor spaces is very essential owing to the amount of time spent indoors. Specifically, the monitoring of air quality is significant because contaminated air affects the health, comfort and productivity of occupants. This research work presents a technology review of prototyping platforms for monitoring ambient conditions in indoor spaces. It involves the research on sensors (for CO 2 , air quality and ambient conditions), IoT platforms, and novel and commercial prototyping platforms. The ultimate objective of this review is to enable the easy identification, selection and utilisation of the technologies best suited for monitoring ambient conditions in indoor spaces. Following the review, it is recommended to use metal oxide sensors, optical sensors and electrochemical sensors for IAQ monitoring (including NDIR sensors for CO 2 monitoring), Raspberry Pi for data processing, ZigBee and Wi-Fi for data communication, and ThingSpeak IoT platform for data storage, analysis and visualisation.

Heterogeneous photo-oxidation of pesticides and its implication to their environmental fate

NASA Astrophysics Data System (ADS)

Dubowski, Y.

2014-12-01

The environmental fate and impact of pesticides strongly depend on their post application degradation processes. While most existing knowledge on pesticides degradation refers to processes within bulk soil and water, applied pesticides may remain on treated surfaces (and on airborn particles) for long duration, exposed to atmospheric oxidants and solar radiation. The resulting photo-oxidation processes may have significant effect on their fate, especially in semiarid regions where pesticide applications take place during the long dry season and targeted irrigation is common. Here we present our studies on heterogeneous photo-oxidation of few commonly used pesticides (e.g., cypermethrin, methyl parathion, and chlorpyrifos), using novel laboratory setups enabling simultaneous monitoring of both phases. Experiments focused on kinetics, quantum yields, and identification of gaseous and condensed products. In addition, the reactivity of the selected pesticides was investigated as a function of their matrix (analytical vs. commercial formula), their phase (thin film vs. airborne aerosols), and the substrate they are sorbed on (leaf, soil, and glass). Complimentarily to these laboratory studies, field measurements of selected pesticides concentrations in few streams in northern Israel during the first rain events were also conducted and showed the important role of surface processes on these pesticides fate and transport in semi-arid climate.

Polyethyleneglycol/silver functionalized reduced graphene oxide aerogel for environmental application

NASA Astrophysics Data System (ADS)

Kumari, G. Vanitha; Asha, S.; Ananth, A. Nimrodh; Rajan, M. A. Jothi; Mathavan, T.

2018-04-01

Polyethylene glycol (PEG)/Silver (Ag) functionalized reduced graphene oxide aerogel (RGOA) was synthesized. PEG/Ag decorated reduced graphene oxide aerogel was characterized using XRD, Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR). The surface morphology of PEG/Ag/RGOA was analyzed using scanning electron microscope. The non-covalent interaction between reduced graphene oxide layers and the interaction between PEG and Ag on RGOA were studied by FT-IR spectra. It was observed that the interaction between Ag and PEG could enhance the properties of RGOA. Methyl Orange (MO) dye degradation was observed from UV-Vis Spectra. The process was studied by monitoring the simultaneous decrease in the height of UV-Vis absorption peak of dye solution. The results show that PEG/RGOA and PEG/Ag/RGOA are an efficient catalyst for dye degradation.

Multi-model study of mercury dispersion in the atmosphere: atmospheric processes and model evaluation

NASA Astrophysics Data System (ADS)

Travnikov, Oleg; Angot, Hélène; Artaxo, Paulo; Bencardino, Mariantonia; Bieser, Johannes; D'Amore, Francesco; Dastoor, Ashu; De Simone, Francesco; Diéguez, María del Carmen; Dommergue, Aurélien; Ebinghaus, Ralf; Feng, Xin Bin; Gencarelli, Christian N.; Hedgecock, Ian M.; Magand, Olivier; Martin, Lynwill; Matthias, Volker; Mashyanov, Nikolay; Pirrone, Nicola; Ramachandran, Ramesh; Read, Katie Alana; Ryjkov, Andrei; Selin, Noelle E.; Sena, Fabrizio; Song, Shaojie; Sprovieri, Francesca; Wip, Dennis; Wängberg, Ingvar; Yang, Xin

2017-04-01

Current understanding of mercury (Hg) behavior in the atmosphere contains significant gaps. Some key characteristics of Hg processes, including anthropogenic and geogenic emissions, atmospheric chemistry, and air-surface exchange, are still poorly known. This study provides a complex analysis of processes governing Hg fate in the atmosphere involving both measured data from ground-based sites and simulation results from chemical transport models. A variety of long-term measurements of gaseous elemental Hg (GEM) and reactive Hg (RM) concentration as well as Hg wet deposition flux have been compiled from different global and regional monitoring networks. Four contemporary global-scale transport models for Hg were used, both in their state-of-the-art configurations and for a number of numerical experiments to evaluate particular processes. Results of the model simulations were evaluated against measurements. As follows from the analysis, the interhemispheric GEM gradient is largely formed by the prevailing spatial distribution of anthropogenic emissions in the Northern Hemisphere. The contributions of natural and secondary emissions enhance the south-to-north gradient, but their effect is less significant. Atmospheric chemistry has a limited effect on the spatial distribution and temporal variation of GEM concentration in surface air. In contrast, RM air concentration and wet deposition are largely defined by oxidation chemistry. The Br oxidation mechanism can reproduce successfully the observed seasonal variation of the RM / GEM ratio in the near-surface layer, but it predicts a wet deposition maximum in spring instead of in summer as observed at monitoring sites in North America and Europe. Model runs with OH chemistry correctly simulate both the periods of maximum and minimum values and the amplitude of observed seasonal variation but shift the maximum RM / GEM ratios from spring to summer. O3 chemistry does not predict significant seasonal variation of Hg oxidation. Hence, the performance of the Hg oxidation mechanisms under study differs in the extent to which they can reproduce the various observed parameters. This variation implies possibility of more complex chemistry and multiple Hg oxidation pathways occurring concurrently in various parts of the atmosphere.

An Investigation Of The Effect Of Particle Size On Oxidation Of Pyrites In Coal.

NASA Astrophysics Data System (ADS)

Chan, Paul K.; Frost, David C.

1986-08-01

We have used X-ray photoelectron spectroscopy (XPS) to study the variation of surface pyrite density with coal particle size (53 4m - 250 4μm). We also detect and monitor pyrite oxidation to sulfate, an important process influencing the surface-dependency of coal-cleansing methods such as flotation. It is very likely that as coal is crushed as part of the processes employed to rid it of prospective pollutants one eventually reaches a pyrite size which may be called "characteristic". It is this parameter that we examine here. Good correlations are established between (i) the liberation of pyrite and particle size, (ii) surface pyrite/sulfate ratio, and (iii) oxidized and non-oxidized sulfur in a typical Canadian coal. For "non-oxidized", or "fresh" coal, the dispersion of pyrite on the coal surface is inversely proportional to coal particle radius, and the tangents of this curve intersect at a particular particle size (106±5 4μm). Although, for the oxidized coal, the appearance of the curves depend on oxidation time intervals at low temperature with humid air, there is an "optimum" particle size which exhibits maximum surface pyrite. Notably, this "optimum" size corresponds to the tangent's intersection for the non-oxidized coal, and hence the "characteristic" size of constituent pyrite. This should allow prediction of pyrite occurrence, a parameter of paramount interest in coal processing and cleaning technology. Coal surface characterization obtained by XPS after various conditioning steps and during flotation, allow both a functional analysis via the study of chemical shifts and a semi-quantitative analysis based on relative intensity measurements.

Abrupt recent trend changes in atmospheric nitrogen dioxide over the Middle East

PubMed Central

Lelieveld, Jos; Beirle, Steffen; Hörmann, Christoph; Stenchikov, Georgiy; Wagner, Thomas

2015-01-01

Nitrogen oxides, released from fossil fuel use and other combustion processes, affect air quality and climate. From the mid-1990s onward, nitrogen dioxide (NO2) has been monitored from space, and since 2004 with relatively high spatial resolution by the Ozone Monitoring Instrument. Strong upward NO2 trends have been observed over South and East Asia and the Middle East, in particular over major cities. We show, however, that a combination of air quality control and political factors, including economical crisis and armed conflict, has drastically altered the emission landscape of nitrogen oxides in the Middle East. Large changes, including trend reversals, have occurred since about 2010 that could not have been predicted and therefore are at odds with emission scenarios used in projections of air pollution and climate change in the early 21st century. PMID:26601240

Dielectric and electric properties as a tool to investigate the coagulation mechanism during sludge treatment.

PubMed

Mortadi, A; Chahid, El G; Nasrellah, H; Cherkaoui, O; El Moznine, R

2017-09-28

The analysis of the complex permittivity, electrical complex modulus and the hopping conductivity have been employed in order to investigate the impacts of calcium oxide during sludge treatment in textile such as coagulation process. In this context, impedance measurement was performed on five samples, including raw sludge and four compositions containing different amounts of calcium oxide: 2%, 3%, 4% and 5% (w/w). The dielectric spectra of each composition were described by the summation of a power law and a Cole-Cole relaxation model. The relaxation time and the magnitude of the dielectric relaxation obtained from the analysis of dielectric properties showed an increase up to 3% of these parameters with the addition of calcium oxide. Above this critical value, both parameters showed a very small change, suggesting that the aggregation became more stable. In addition, the evolution of the hopping conductivity reached a minimum value at this critical amount (3%). This evolution was well described by a double power law, which allowed us to estimate the optimal amount of the calcium oxide to achieve coagulation process. The analysis of the dielectric properties was found useful in monitoring aggregation processes that occur during the coagulation mechanism in textile sludge.

Monitoring of Soil Remediation Process in the Metal Mining Area

NASA Astrophysics Data System (ADS)

Kim, Kyoung-Woong; Ko, Myoung-Soo; Han, Hyeop-jo; Lee, Sang-Ho; Na, So-Young

2016-04-01

Stabilization using proper additives is an effective soil remediation technique to reduce As mobility in soil. Several researches have reported that Fe-containing materials such as amorphous Fe-oxides, goethite and hematite were effective in As immobilization and therefore acid mine drainage sludge (AMDS) may be potential material for As immobilization. The AMDS is the by-product from electrochemical treatment of acid mine drainage and mainly contains Fe-oxide. The Chungyang area in Korea is located in the vicinity of the huge abandoned Au-Ag Gubong mine which was closed in the 1970s. Large amounts of mine tailings have been remained without proper treatment and the mobilization of mine tailings can be manly occurred during the summer heavy rainfall season. Soil contamination from this mobilization may become an urgent issue because it can cause the contamination of groundwater and crop plants in sequence. In order to reduce the mobilization of the mine tailings, the pilot scale study of in-situ stabilization using AMDS was applied after the batch and column experiments in the lab. For the monitoring of stabilization process, we used to determine the As concentration in crop plants grown on the field site but it is not easily applicable because of time and cost. Therefore, we may need simple monitoring technique to measure the mobility or leachability which can be comparable with As concentration in crop plants. We compared several extraction methods to suggest the representative single extraction method for the monitoring of soil stabilization efficiency. Several selected extraction methods were examined and Mehlich 3 extraction method using the mixture of NH4F, EDTA, NH4NO3, CH3COOH and HNO3 was selected as the best predictor of the leachability or mobility of As in the soil remediation process.

Developing uranium dicarbide-graphite porous materials for the SPES project

NASA Astrophysics Data System (ADS)

Biasetto, L.; Zanonato, P.; Carturan, S.; Di Bernardo, P.; Colombo, P.; Andrighetto, A.; Prete, G.

2010-09-01

Uranium carbide dispersed in graphite was produced under vacuum by means of carbothermic reduction of different uranium oxides (UO 2, U 3O 8 and UO 3), using graphite as the source of carbon. The thermal process was monitored by mass spectrometry and the gas evolution confirmed the reduction of the U 3O 8 and UO 3 oxides to UO 2 before the carbothermic reaction, that started to occur at T > 1000 °C. XRD analysis confirmed the formation of α-UC 2 and of a minor amount of UC. The morphology of the produced uranium carbide was not affected by the oxides employed as the source of uranium.

End-of-fabrication CMOS process monitor

NASA Technical Reports Server (NTRS)

Buehler, M. G.; Allen, R. A.; Blaes, B. R.; Hannaman, D. J.; Lieneweg, U.; Lin, Y.-S.; Sayah, H. R.

1990-01-01

A set of test 'modules' for verifying the quality of a complementary metal oxide semiconductor (CMOS) process at the end of the wafer fabrication is documented. By electrical testing of specific structures, over thirty parameters are collected characterizing interconnects, dielectrics, contacts, transistors, and inverters. Each test module contains a specification of its purpose, the layout of the test structure, the test procedures, the data reduction algorithms, and exemplary results obtained from 3-, 2-, or 1.6-micrometer CMOS/bulk processes. The document is intended to establish standard process qualification procedures for Application Specific Integrated Circuits (ASIC's).

Monitoring changes in acid value, total polar material, and antioxidant capacity of oils used for frying chicken.

PubMed

Song, JuHee; Kim, Mi-Ja; Kim, Young-Jun; Lee, JaeHwan

2017-04-01

Oxidation products and tocol homologues were monitored in oils during chicken frying to determine the discarding point of highly used frying oils. Oils were heated without chicken for 170h while chicken frying was performed 130 cycles at 180°C. As heating time and frying cycles increased, all oxidation parameters including acid value, total polar materials (TPM), conjugated dienoic acid (CDA), and p-anisidine values (p-AV) increased significantly (p<0.05). γ-Tocopherol and γ-tocotrienol had the lowest stability in oils during heating or frying processes compared to other tocol homologues. TPM values over 24% were obtained after about 109h for heated oil and 100 cycles for oils used to fry chicken. A decrease of 2,2-diphenyl-1-picrylhydrazyl (DPPH) in isooctane and methanol was highly correlated with the formation of TPM in oils during the frying process. Both DPPH loss and TPM values could be applied to determine the discarding points of highly used frying oils. Copyright © 2016 Elsevier Ltd. All rights reserved.

Research on filling process of fuel and oxidant during detonation based on absorption spectrum technology

NASA Astrophysics Data System (ADS)

Lv, Xiao-Jing; Li, Ning; Weng, Chun-Sheng

2014-12-01

Research on detonation process is of great significance for the control optimization of pulse detonation engine. Based on absorption spectrum technology, the filling process of fresh fuel and oxidant during detonation is researched. As one of the most important products, H2O is selected as the target of detonation diagnosis. Fiber distributed detonation test system is designed to enable the detonation diagnosis under adverse conditions in detonation process. The test system is verified to be reliable. Laser signals at different working frequency (5Hz, 10Hz and 20Hz) are detected. Change of relative laser intensity in one detonation circle is analyzed. The duration of filling process is inferred from the change of laser intensity, which is about 100~110ms. The peak of absorption spectrum is used to present the concentration of H2O during the filling process of fresh fuel and oxidant. Absorption spectrum is calculated, and the change of absorption peak is analyzed. Duration of filling process calculated with absorption peak consisted with the result inferred from the change of relative laser intensity. The pulse detonation engine worked normally and obtained the maximum thrust at 10Hz under experiment conditions. The results are verified through H2O gas concentration monitoring during detonation.

Randomized controlled study of the safety and efficacy of nitrous oxide-sedated endoscopic ultrasound-guided fine needle aspiration for digestive tract diseases.

PubMed

Wang, Cai-Xia; Wang, Jian; Chen, Yuan-Yuan; Wang, Jia-Ni; Yu, Xin; Yang, Feng; Sun, Si-Yu

2016-12-14

To evaluate the efficacy and safety of nitrous oxide-sedated endoscopic ultrasound-guided fine needle aspiration. Enrolled patients were divided randomly into an experimental group (inhalation of nitrous oxide) and a control group (inhalation of pure oxygen) and heart rate, blood oxygen saturation, blood pressure, electrocardiogram (ECG) changes, and the occurrence of complications were monitored and recorded. All patients and physicians completed satisfaction questionnaires about the examination and scored the process using a visual analog scale. There was no significant difference in heart rate, blood oxygen saturation, blood pressure, ECG changes, or complication rate between the two groups of patients ( P > 0.05). However, patient and physician satisfaction were both significantly higher in the nitrous oxide compared with the control group ( P < 0.05). Nitrous oxide-sedation is a safe and effective option for patients undergoing endoscopic ultrasound-guided fine needle aspiration.

Characteristics and fate of natural organic matter during UV oxidation processes.

PubMed

Ahn, Yongtae; Lee, Doorae; Kwon, Minhwan; Choi, Il-Hwan; Nam, Seong-Nam; Kang, Joon-Wun

2017-10-01

Advanced oxidation processes (AOPs) are widely used in water treatments. During oxidation processes, natural organic matter (NOM) is modified and broken down into smaller compounds that affect the characteristics of the oxidized NOM by AOPs. In this study, NOM was characterized and monitored in the UV/hydrogen peroxide (H 2 O 2 ) and UV/persulfate (PS) processes using a liquid chromatography-organic carbon detector (LC-OCD) technique, and a combination of excitation-emission matrices (EEM) and parallel factor analysis (PARAFAC). The percentages of mineralization of NOM in the UV/H 2 O 2 and UV/PS processes were 20.5 and 83.3%, respectively, with a 10 mM oxidant dose and a contact time of 174 s (UV dose: approximately 30,000 mJ). Low-pressure, Hg UV lamp (254 nm) was applied in this experiment. The steady-state concentration of SO 4 - was 38-fold higher than that of OH at an oxidant dose of 10 mM. With para-chlorobenzoic acid (pCBA) as a radical probe compound, we experimentally determined the rate constants of Suwannee River NOM (SRNOM) with OH (k OH/NOM  = 3.3 × 10 8  M -1 s -1 ) and SO 4 - (k SO4-/NOM  = 4.55 × 10 6  M -1 s -1 ). The hydroxyl radical and sulfate radical showed different mineralization pathways of NOM, which have been verified by the use of LC-OCD and EEM/PARAFAC. Consequently, higher steady-state concentrations of SO 4 - , and different reaction preferences of OH and SO 4 - with the NOM constituent had an effect on the mineralization efficiency. Copyright © 2017 Elsevier Ltd. All rights reserved.

40 CFR 63.3168 - What are the requirements for continuous parameter monitoring system installation, operation, and...

Code of Federal Regulations, 2011 CFR

2011-07-01

... paragraphs (c)(1) through (3) of this section: (1) For a thermal oxidizer, install a gas temperature monitor... any substantial heat exchange occurs. (2) For a catalytic oxidizer, install a gas temperature monitor....3167(b)(1) through (3), you must also install a gas temperature monitor downstream of the catalyst bed...

40 CFR 63.3168 - What are the requirements for continuous parameter monitoring system installation, operation, and...

Code of Federal Regulations, 2010 CFR

2010-07-01

... paragraphs (c)(1) through (3) of this section: (1) For a thermal oxidizer, install a gas temperature monitor... any substantial heat exchange occurs. (2) For a catalytic oxidizer, install a gas temperature monitor....3167(b)(1) through (3), you must also install a gas temperature monitor downstream of the catalyst bed...

Cluster-to-cluster transformation among Au6, Au8 and Au11 nanoclusters.

PubMed

Ren, Xiuqing; Fu, Junhong; Lin, Xinzhang; Fu, Xuemei; Yan, Jinghui; Wu, Ren'an; Liu, Chao; Huang, Jiahui

2018-05-22

We present the cluster-to-cluster transformations among three gold nanoclusters, [Au6(dppp)4]2+ (Au6), [Au8(dppp)4Cl2]2+ (Au8) and [Au11(dppp)5]3+ (Au11). The conversion process follows a rule that states that the transformation of a small cluster to a large cluster is achieved through an oxidation process with an oxidizing agent (H2O2) or with heating, while the conversion of a large cluster to a small one occurs through a reduction process with a reducing agent (NaBH4). All the reactions were monitored using UV-Vis spectroscopy and ESI-MS. This work may provide an alternative approach to the synthesis of novel gold nanoclusters and a further understanding of the structural transformation relationship of gold nanoclusters.

Band bending at the heterointerface of GaAs/InAs core/shell nanowires monitored by synchrotron X-ray photoelectron spectroscopy

NASA Astrophysics Data System (ADS)

Khanbabaee, B.; Bussone, G.; Knutsson, J. V.; Geijselaers, I.; Pryor, C. E.; Rieger, T.; Demarina, N.; Grützmacher, D.; Lepsa, M. I.; Timm, R.; Pietsch, U.

2016-10-01

Unique electronic properties of semiconductor heterostructured nanowires make them useful for future nano-electronic devices. Here, we present a study of the band bending effect at the heterointerface of GaAs/InAs core/shell nanowires by means of synchrotron based X-ray photoelectron spectroscopy. Different Ga, In, and As core-levels of the nanowire constituents have been monitored prior to and after cleaning from native oxides. The cleaning process mainly affected the As-oxides and was accompanied by an energy shift of the core-level spectra towards lower binding energy, suggesting that the As-oxides turn the nanowire surfaces to n-type. After cleaning, both As and Ga core-levels revealed an energy shift of about -0.3 eV for core/shell compared to core reference nanowires. With respect to depth dependence and in agreement with calculated strain distribution and electron quantum confinement, the observed energy shift is interpreted by band bending of core-levels at the heterointerface between the GaAs nanowire core and the InAs shell.

Laboratory Measurements of Gas Phase Pyrolysis Products from Southern Wildland Fuels using Infrared Spectroscopy

NASA Astrophysics Data System (ADS)

Scharko, N.; Safdari, S.; Danby, T. O.; Howarth, J.; Beiswenger, T. N.; Weise, D.; Myers, T. L.; Fletcher, T. H.; Johnson, T. J.

2017-12-01

Combustion is an oxidation reaction that occurs when there is less fuel available than oxidizers, while pyrolysis is a thermal decomposition process that occurs under "fuel rich" conditions where all of the available oxidizers are consumed leaving some fuel(s) either unreacted or partially reacted. Gas-phase combustion products from biomass burning experiments have been studied extensively; less is known, however, about pyrolysis processes and products. Pyrolysis is the initial reaction occurring in the burning process and generates products that are subsequently oxidized during combustion, yielding highly-oxidized chemicals. This laboratory study investigates the pyrolysis processes by using an FTIR spectrometer to detect and quantify the gas-phase products from thermal decomposition of intact understory fuels from forests in the southeastern United States. In particular, a laboratory flat-flame burner operating under fuel rich conditions (no oxygen) was used to heat individual leaves to cause decomposition. The gas-phase products were introduced to an 8 meter gas cell coupled to an infrared spectrometer were used to monitor the products. Trace gas emissions along with emission ratios, which are calculated by dividing the change in the amount of the trace gas by the change in the amount of CO, for the plant species, gallberry (Ilex glabra) and swampbay (Persea palustris) were determined. Preliminary measurements observed species such as CO2, CO, C2H2, C2H4, HCHO, CH3OH, isoprene, 1,3-butadiene, phenol and NH3 being produced as part of the thermal decomposition process. It is important to note that FTIR will not detect H2.

Annual Reporting of Monitoring at Morrill, Kansas in 2015

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

LaFreniere, Lorraine M.

In September 2005, the CCC/USDA initiated periodic sampling of groundwater, in accord with a program (Argonne 2005b) approved by the KDHE (2005), to monitor carbon tetrachloride concentrations in the groundwater. Under the KDHE-approved monitoring plan (Argonne 2005b), groundwater was sampled twice yearly for VOCs analyses through 2011. During the initial two years of monitoring, analysis for selected geochemical parameters was also conducted to aid in the evaluation of possible natural contaminant degradation (reductive dechlorination) processes in the subsurface environment. Consistently low levels of dissolved oxygen (DO) and oxidation-reduction potential (ORP) at monitoring well MW1D (in the deepest portion of themore » contaminated aquifer) and the presence of chloroform (the primary degradation product of carbon tetrachloride) suggested that some degree of reductive dechlorination was occurring.« less

Improving alachlor biodegradability by ferrate oxidation.

PubMed

Zhu, Jian-Hang; Yan, Xi-Luan; Liu, Ye; Zhang, Bao

2006-07-31

Alachlor can be recalcitrant when present at high concentrations in wastewater. Ferrate oxidation was used as a pretreatment to improve its biodegradability and was evaluated by monitoring alachlor elimination and removal of COD(Cr) (chemical oxygen demand determined by potassium dichromate) during the oxidation process up to a value compatible with biological treatment. Ferrate oxidation resulted in elimination of alachlor followed by degradation of its intermediates. High pH suppressed alachlor removal and COD(Cr) removal due to the low redox potential of ferrate ions. Although alachlor can be totally eliminated within 10 min under optimized conditions (alachlor, 40 mg l(-1); ferrate:alachlor molar ratio, 2; and pH 7.0), its complete mineralization cannot be achieved by ferrate oxidation alone. Alachlor solution treated by ferrate for 10 min inhibited an up-flow biotreatment with activated sludge. The biodegradability of ferrate-pretreated solution improved when the treatment was increased to 20 min, at the point of which BOD(5)/COD(Cr) ratio of the treated solution was increased to 0.87 from 0.35 after 10 min treatment. Under optimized conditions, ferrate oxidation for 20 min resulted in total elimination of alachlor, partial removal of COD(Cr) and the ferrate-treated solution could be effectively treated by the up-flow activated sludge process.

Instrumentation for Air Pollution Monitoring

ERIC Educational Resources Information Center

Hollowell, Craig D.; McLaughlin, Ralph D.

1973-01-01

Describes the techniques which form the basis of current commercial instrumentation for monitoring five major gaseous atmospheric pollutants (sulfur dioxide, oxides of nitrogen, oxidants, carbon monoxide, and hydrocarbons). (JR)

Single Molecule Enzymology via Nanoelectronic Circuits

NASA Astrophysics Data System (ADS)

Collins, Philip

Traditional single-molecule techniques rely on fluorescence or force transduction to monitor conformational changes and biochemical activity. Recent demonstrations of single-molecule monitoring with electronic transistors are poised to add to the single-molecule research toolkit. The transistor-based technique is sensitive to the motion of single charged side chain residues and can transduce those motions with microsecond resolution, opening the doors to single-molecule enzymology with unprecedented resolution. Furthermore, the solid-state platform provides opportunities for parallelization in arrays and long-duration monitoring of one molecule's activity or processivity, all without the limitations caused by photo-oxidation or mutagenic fluorophore incorporation. This presentation will review some of these advantages and their particular application to DNA polymerase I processing single-stranded DNA templates. This research was supported financially by the NIH NCI (R01 CA133592-01), the NIH NIGMS (1R01GM106957-01) and the NSF (DMR-1104629 and ECCS-1231910).

Interactions of Graphene Oxide Nanomaterials with Natural Organic Matter and Metal Oxide Surfaces

EPA Science Inventory

Interactions of graphene oxide (GO) with silica surfaces were investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D). Both GO deposition and release were monitored on silica- and poly-l-lysine (PLL) coated surfaces as a function of GO concentration a...

Detection of Cysteine Redox States in Mitochondrial Proteins in Intact Mammalian Cells.

PubMed

Habich, Markus; Riemer, Jan

2017-01-01

Import, folding, and activity regulation of mitochondrial proteins are important for mitochondrial function. Cysteine residues play crucial roles in these processes as their thiol groups can undergo (reversible) oxidation reactions. For example, during import of many intermembrane space (IMS) proteins, cysteine oxidation drives protein folding and translocation over the outer membrane. Mature mitochondrial proteins can undergo changes in the redox state of specific cysteine residues, for example, as part of their enzymatic reaction cycle or as adaptations to changes of the local redox environment which might influence their activity. Here we describe methods to study changes in cysteine residue redox states in intact cells. These approaches allow to monitor oxidation-driven protein import as well as changes of cysteine redox states in mature proteins during oxidative stress or during the reaction cycle of thiol-dependent enzymes like oxidoreductases.

Oxidation of carbon monoxide, hydrogen peroxide and water at a boron doped diamond electrode: the competition for hydroxyl radicals.

PubMed

Kisacik, Izzet; Stefanova, Ana; Ernst, Siegfried; Baltruschat, Helmut

2013-04-07

Boron doped diamond (BDD) electrodes have an extremely high over-voltage for oxygen evolution from water, which favours its use in oxidation processes of other compounds at high potentials. We used a rotating ring disc (RRDE) assembly and differential electrochemical mass spectrometry (DEMS) in order to monitor the consumption or the production of species in the course of the electrode processes. By intercepting the intermediate of the electrochemical water oxidation with chemical reactions we demonstrate clearly, albeit indirectly, that in the water oxidation process at BDD above 2.5 V the first step is the formation of ˙OH radicals. The electro-oxidation of CO to CO2 at BDD electrodes proceeds only via a first attack by ˙OH radicals followed by a further electron transfer to the electrode. At potentials below the onset of oxygen evolution from water, H2O2 is oxidised by a direct electron transfer to the BDD electrode, while at higher potentials, two different reactions paths compete for the ˙OH radicals formed in the first electron transfer from water: one, where these ˙OH radicals react with each other followed by further electron transfers leading to O2 on the one hand and one, where ˙OH radicals react with other species like H2O2 or CO with subsequent electron transfers on the other hand.

Investigation of hair dye deposition, hair color loss, and hair damage during multiple oxidative dyeing and shampooing cycles.

PubMed

Zhang, Guojin; McMullen, Roger L; Kulcsar, Lidia

2016-01-01

Color fastness is a major concern for consumers and manufacturers of oxidative hair dye products. Hair dye loss results from multiple wash cycles in which the hair dye is dissolved by water and leaches from the hair shaft. In this study, we carried out a series of measurements to help us better understand the kinetics of the leaching process and pathways associated with its escape from the fiber. Hair dye leaching kinetics was measured by suspending hair in a dissolution apparatus and monitoring the dye concentration in solution (leached dye) with an ultraviolet-visible spectrophotometer. The physical state of dye deposited in hair fibers was evaluated by a reflectance light microscopy technique, based on image stacking, allowing enhanced depth of field imaging. The dye distribution within the fiber was monitored by infrared spectroscopic imaging of hair fiber cross sections. Damage to the ultrafine structure of the hair cuticle (surface, endocuticle, and cell membrane complex) and cortex (cell membrane complex) was determined in hair cross sections and on the hair fiber surface with atomic force microscopy. Using differential scanning calorimetry, we investigated how consecutive coloring and leaching processes affect the internal proteins of hair. Further, to probe the surface properties of hair we utilized contact angle measurements. This study was conducted on both pigmented and nonpigmented hair to gain insight into the influence of melanin on the hair dye deposition and leaching processes. Both types of hair were colored utilizing a commercial oxidative hair dye product based on pyrazole chemistry.

Characterization of N3 dye adsorption on TiO2 using quartz-crystal microbalance with dissipation monitoring

NASA Astrophysics Data System (ADS)

Wayment-Steele, Hannah K.; Johnson, Lewis E.; Dixon, Matthew C.; Johal, Malkiat S.

2013-09-01

Understanding the kinetics of dye adsorption on semiconductors is crucial for designing dye-sensitized solar cells (DSSCs) with enhanced efficiency. Harms et al. recently applied the Quartz-Crystal Microbalance with Dissipation Monitoring (QCM-D) to study in situ dye adsorption on flat TiO2 surfaces. QCM-D measures adsorption in real time and therefore allows one to determine the kinetics of the process. In this work, we characterize the adsorption of N3, a commercial RuBipy dye, using the native oxide layer of a titanium sensor to simulate the TiO2 substrate of a DSSC. We report equilibrium constants that are in agreement with previous absorbance studies of N3 adsorption, and therefore demonstrate the native oxide layer of a titanium sensor as a valid and readily available planar TiO2 morphology to study dye adsorption.

Chemical-oxidative scrubbing for the removal of hydrogen sulphide from raw biogas: potentials and economics.

PubMed

Miltner, M; Makaruk, A; Krischan, J; Harasek, M

2012-01-01

In the present work chemical-oxidative scrubbing as a novel method for the desulphurisation of raw biogas is presented with a special focus on the process potentials and economics. The selective absorption of hydrogen sulphide from gas streams containing high amounts of carbon dioxide using caustic solutions is not trivial but has been treated in literature. However, the application of this method to biogas desulphurisation has not been established so far. Based on rigorous experimental work, an industrial-scale pilot plant has been designed, erected and commissioned at a biogas plant with biogas upgrading and gas grid injection in Austria. Data collected from the 12-month monitored operation has been used to elaborate performance as well as economic parameters for the novel desulphurisation method. The proposed technology offers significant operational advantages regarding the degree of automation and the flexibility towards fluctuations in process boundary conditions. Furthermore, the economic assessment revealed the high competitiveness of the chemical-oxidative scrubbing process compared with other desulphurisation technologies with the named advantageous operational behaviour.

Application of a Chemiluminescence Detector for the Measurement of Total Oxides of Nitrogen and Ammonia in the Atmosphere

NASA Technical Reports Server (NTRS)

Hodgeson, J. A.; Bell, J. P.; Rehme, K. A.; Krost, K. J.; Stevens, R. K.

1971-01-01

By means of the thermal conversion of nitrogen dioxide to the nitric oxide, the chemiluminescent nitric oxide monitor, based on the nitric oxide plus ozone reaction, may be used for monitoring nitrogen dioxide plus nitric oxide (NO(x)). Under conditions previously described, ammonia is also converted to nitric oxide and therefore interferes. A metal surface, gold wool or stainless steel, operated at two different temperatures has been used to convert only nitrogen dioxide or nitrogen dioxide plus ammonia. Quantitative conversion of nitrogen dioxide to nitric oxide has been obtained at temperatures as low as 200 C. Conversion of ammonia is effected at temperatures of 300 C or higher. By the addition of a converter the basic nitric oxide monitor may be used for measuring NO(x) or NO(x) plus ammonia. As an alternate mode, for a fixed high temperature, a specific scrubber is described for removing NH3 without affecting NO2 concentrations.

Graphene Nanoprobes for Real-Time Monitoring of Isothermal Nucleic Acid Amplification.

PubMed

Li, Fan; Liu, Xiaoguo; Zhao, Bin; Yan, Juan; Li, Qian; Aldalbahi, Ali; Shi, Jiye; Song, Shiping; Fan, Chunhai; Wang, Lihua

2017-05-10

Isothermal amplification is an efficient way to amplify DNA with high accuracy; however, the real-time monitoring for quantification analysis mostly relied on expensive and precisely designed probes. In the present study, a graphene oxide (GO)-based nanoprobe was used to real-time monitor the isothermal amplification process. The interaction between GO and different DNA structures was systematically investigated, including single-stranded DNA (ssDNA), double-stranded DNA (dsDNA), DNA 3-helix, and long rolling circle amplification (RCA) and hybridization chain reaction (HCR) products, which existed in one-, two-, and three-dimensional structures. It was found that the high rigid structures exhibited much lower affinity with GO than soft ssDNA, and generally the rigidity was dependent on the length of targets and the hybridization position with probe DNA. On the basis of these results, we successfully monitored HCR amplification process, RCA process, and the enzyme restriction of RCA products with GO nanoprobe; other applications including the detection of the assembly/disassembly of DNA 3-helix structures were also performed. Compared to the widely used end-point detection methods, the GO-based sensing platform is simple, sensitive, cost-effective, and especially in a real-time monitoring mode. We believe such studies can provide comprehensive understandings and evocation on design of GO-based biosensors for broad application in various fields.

Proton mediated control of biochemical reactions with bioelectronic pH modulation

NASA Astrophysics Data System (ADS)

Deng, Yingxin; Miyake, Takeo; Keene, Scott; Josberger, Erik E.; Rolandi, Marco

2016-04-01

In Nature, protons (H+) can mediate metabolic process through enzymatic reactions. Examples include glucose oxidation with glucose dehydrogenase to regulate blood glucose level, alcohol dissolution into carboxylic acid through alcohol dehydrogenase, and voltage-regulated H+ channels activating bioluminescence in firefly and jellyfish. Artificial devices that control H+ currents and H+ concentration (pH) are able to actively influence biochemical processes. Here, we demonstrate a biotransducer that monitors and actively regulates pH-responsive enzymatic reactions by monitoring and controlling the flow of H+ between PdHx contacts and solution. The present transducer records bistable pH modulation from an “enzymatic flip-flop” circuit that comprises glucose dehydrogenase and alcohol dehydrogenase. The transducer also controls bioluminescence from firefly luciferase by affecting solution pH.

Separating and stabilizing phosphate from high-level radioactive waste: process development and spectroscopic monitoring.

PubMed

Lumetta, Gregg J; Braley, Jenifer C; Peterson, James M; Bryan, Samuel A; Levitskaia, Tatiana G

2012-06-05

Removing phosphate from alkaline high-level waste sludges at the Department of Energy's Hanford Site in Washington State is necessary to increase the waste loading in the borosilicate glass waste form that will be used to immobilize the highly radioactive fraction of these wastes. We are developing a process which first leaches phosphate from the high-level waste solids with aqueous sodium hydroxide, and then isolates the phosphate by precipitation with calcium oxide. Tests with actual tank waste confirmed that this process is an effective method of phosphate removal from the sludge and offers an additional option for managing the phosphorus in the Hanford tank waste solids. The presence of vibrationally active species, such as nitrate and phosphate ions, in the tank waste processing streams makes the phosphate removal process an ideal candidate for monitoring by Raman or infrared spectroscopic means. As a proof-of-principle demonstration, Raman and Fourier transform infrared (FTIR) spectra were acquired for all phases during a test of the process with actual tank waste. Quantitative determination of phosphate, nitrate, and sulfate in the liquid phases was achieved by Raman spectroscopy, demonstrating the applicability of Raman spectroscopy for the monitoring of these species in the tank waste process streams.

Laser-Induced, Local Oxidation of Copper Nanoparticle Films During Raman Measurements

NASA Astrophysics Data System (ADS)

Hight Walker, Angela R.; Cheng, Guangjun; Calizo, Irene

2011-03-01

The optical properties of gold and silver nanoparticles and their films have been thoroughly investigated as surface enhanced Raman scattering (SERS) substrates and chemical reaction promoters. Similar to gold and silver nanoparticles, copper nanoparticles exhibit distinct plasmon absorptions in the visible region. The work on copper nanoparticles and their films is limited due to their oxidization in air. However, their high reactivity actually provides an opportunity to exploit the laser-induced thermal effect and chemical reactions of these nanoparticles. Here, we present our investigation of the local oxidation of a copper nanoparticle film induced by a visible laser source during Raman spectroscopic measurements. The copper nanoparticle film is prepared by drop-casting chemically synthesized copper colloid onto silicon oxide/silicon substrate. The local oxidation induced by visible lasers in Raman spectroscopy is monitored with the distinct scattering peaks for copper oxides. Optical microscopy and scanning electron microscopy have been used to characterize the laser-induced morphological changes in the film. The results of this oxidation process with different excitation wavelengths and different laser powers will be presented.

Monitoring by Control Technique - Catalytic Oxidizer

EPA Pesticide Factsheets

Stationary source emissions monitoring is required to demonstrate that a source is meeting the requirements in Federal or state rules. This page is about catalytic oxidizer control techniques used to reduce pollutant emissions.

Monitoring by Control Technique - Thermal Oxidizer

EPA Pesticide Factsheets

Stationary source emissions monitoring is required to demonstrate that a source is meeting the requirements in Federal or state rules. This page is about thermal oxidizer control techniques used to reduce pollutant emissions.

Electric terminal performance and characterization of solid oxide fuel cells and systems

NASA Astrophysics Data System (ADS)

Lindahl, Peter Allan

Solid Oxide Fuel Cells (SOFCs) are electrochemical devices which can effect efficient, clean, and quiet conversion of chemical to electrical energy. In contrast to conventional electricity generation systems which feature multiple discrete energy conversion processes, SOFCs are direct energy conversion devices. That is, they feature a fully integrated chemical to electrical energy conversion process where the electric load demanded of the cell intrinsically drives the electrochemical reactions and associated processes internal to the cell. As a result, the cell's electric terminals provide a path for interaction between load side electric demand and the conversion side processes. The implication of this is twofold. First, the magnitude and dynamic characteristics of the electric load demanded of the cell can directly impact the long-term efficacy of the cell's chemical to electrical energy conversion. Second, the electric terminal response to dynamic loads can be exploited for monitoring the cell's conversion side processes and used in diagnostic analysis and degradation-mitigating control schemes. This dissertation presents a multi-tier investigation into this electric terminal based performance characterization of SOFCs through the development of novel test systems, analysis techniques and control schemes. First, a reference-based simulation system is introduced. This system scales up the electric terminal performance of a prototype SOFC system, e.g. a single fuel cell, to that of a full power-level stack. This allows realistic stack/load interaction studies while maintaining explicit ability for post-test analysis of the prototype system. Next, a time-domain least squares fitting method for electrochemical impedance spectroscopy (EIS) is developed for reduced-time monitoring of the electrochemical and physicochemical mechanics of the fuel cell through its electric terminals. The utility of the reference-based simulator and the EIS technique are demonstrated through their combined use in the performance testing of a hybrid-source power management (HSPM) system designed to allow in-situ EIS monitoring of a stack under dynamic loading conditions. The results from the latter study suggest that an HSPM controller allows an opportunity for in-situ electric terminal monitoring and control-based mitigation of SOFC degradation. As such, an exploration of control-based SOFC degradation mitigation is presented and ideas for further work are suggested.

Mechanisms involved in the development of diabetic retinopathy induced by oxidative stress.

PubMed

Guzman, David Calderón; Olguín, Hugo Juárez; García, Ernestina Hernández; Peraza, Armando Valenzuela; de la Cruz, Diego Zamora; Soto, Monica Punzo

2017-01-01

Diabetic retinopathy (DR) is one of the main complications in patients with diabetes and has been the leading cause of visual loss since 1990. Oxidative stress is a biological process resulting from excessive production of reactive oxygen species (ROS). This process contributes to the development of many diseases and disease complications. ROS interact with various cellular components to induce cell injury. Fortunately, there is an antioxidan t system that protects organisms against ROS. Indeed, when ROS exceed antioxidant capacity, the resulting cell injury can cause diverse physiological and pathological changes that could lead to a disease like DR. This paper reviews the possible mechanisms of common and novel biomarkers involved in the development of DR and explores how these biomarkers could be used to monitor the damage induced by oxidative stress in DR, which is a significant complication in people with diabetes. The poor control of glucemy in pacients with DB has been shown contribute to the development of complications in eyes as DR.

Development of a tritium monitor combined with an electrochemical tritium pump using a proton conducting oxide

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

Tanaka, M.; Sugiyama, T.

2015-03-15

The detection of low level tritium is one of the key issues for tritium management in tritium handling facilities. Such a detection can be performed by tritium monitors based on proton conducting oxide technique. We tested a tritium monitoring system composed of a commercial proportional counter combined with an electrochemical hydrogen pump equipped with CaZr{sub 0.9}In{sub 0.1}O{sub 3-α} as proton conducting oxide. The hydrogen pump operated at 973 K under electrolysis conditions using tritiated water vapor (HTO). The proton conducting oxide extracts tritium molecules (HT) from HTO and tritium concentration is measured by the proportional counter. The advantage of themore » proposed tritium monitoring system is that it is able to convert HTO into molecular hydrogen.« less

Tribological interaction between polytetrafluoroethylene and silicon oxide surfaces

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

Uçar, A.; Çopuroğlu, M.; Suzer, S., E-mail: suzer@fen.bilkent.edu.tr

2014-10-28

We investigated the tribological interaction between polytetrafluoroethylene (PTFE) and silicon oxide surfaces. A simple rig was designed to bring about a friction between the surfaces via sliding a piece of PTFE on a thermally oxidized silicon wafer specimen. A very mild inclination (∼0.5°) along the sliding motion was also employed in order to monitor the tribological interaction in a gradual manner as a function of increasing contact force. Additionally, some patterns were sketched on the silicon oxide surface using the PTFE tip to investigate changes produced in the hydrophobicity of the surface, where the approximate water contact angle was 45°more » before the transfer. The nature of the transferred materials was characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). XPS results revealed that PTFE was faithfully transferred onto the silicon oxide surface upon even at the slightest contact and SEM images demonstrated that stable morphological changes could be imparted onto the surface. The minimum apparent contact pressure to realize the PTFE transfer is estimated as 5 kPa, much lower than reported previously. Stability of the patterns imparted towards many chemical washing processes lead us to postulate that the interaction is most likely to be chemical. Contact angle measurements, which were carried out to characterize and monitor the hydrophobicity of the silicon oxide surface, showed that upon PTFE transfer the hydrophobicity of the SiO{sub 2} surface could be significantly enhanced, which might also depend upon the pattern sketched onto the surface. Contact angle values above 100° were obtained.« less

Comparative study of the oxidation behavior of sulfur-containing amino acids and glutathione by electrochemistry-mass spectrometry in the presence and absence of cisplatin.

PubMed

Zabel, Robert; Weber, Günther

2016-02-01

Small sulfur-containing compounds are involved in several important biochemical processes, including-but not limited to-redox regulation and drug conjugation/detoxification. While methods for stable redox pairs of such compounds (thiols/disulfides) are available, analytical data on more labile and short-lived redox intermediates are scarce, due to highly challenging analytical requirements. In this study, we employ the direct combination of reagentless electrochemical oxidation and mass spectrometric (EC-MS) identification for monitoring oxidation reactions of cysteine, N-acetylcysteine, methionine, and glutathione under simulated physiological conditions (pH 7.4, 37 °C). For the first time, all theoretically expected redox intermediates-with only one exception-are detected simultaneously and in situ, including sulfenic, sulfinic, and sulfonic acids, disulfides, thiosulfinates, thiosulfonates, and sulfoxides. By monitoring the time/potential-dependent interconversion of sulfur species, mechanistic oxidation routes are confirmed and new reactions detected, e.g., sulfenamide formation due to reaction with ammonia from the buffer. Furthermore, our results demonstrate a highly significant impact of cisplatin on the redox reactivity of sulfur species. Namely, the amount of thiol oxidation to sulfonic acid via sulfenic and sulfinic acid intermediates is diminished for glutathione in the presence of cisplatin in favor of the disulfide formation, while for N-acetylcysteine the contrary applies. N-acetylcysteine is the only ligand which displays enhanced oxidation currents upon cisplatin addition, accompanied by increased levels of thiosulfinate and thiosulfonate species. This is traced back to thiol reactivity and highlights the important role of sulfenic acid intermediates, which may function as a switch between different oxidation routes.

Oxidative Ionization Under Certain Negative-Ion Mass Spectrometric Conditions

NASA Astrophysics Data System (ADS)

Hassan, Isra; Pavlov, Julius; Errabelli, Ramu; Attygalle, Athula B.

2017-02-01

1,4-Hydroquinone and several other phenolic compounds generate (M - 2) -• radical-anions, rather than deprotonated molecules, under certain negative-ion mass spectrometric conditions. In fact, spectra generated under helium-plasma ionization (HePI) conditions from 1,4-hydroquinone and 1,4-benzoquinone (by electron capture) were practically indistinguishable. Because this process involves a net loss of H• and H+, it can be termed oxidative ionization. The superoxide radical-anion (O2 -•), known to be present in many atmospheric-pressure plasma ion sources operated in the negative mode, plays a critical role in the oxidative ionization process. The presence of a small peak at m/z 142 in the spectrum of 1,4-hydroquinone, but not in that of 1,4-benzoquinone, indicated that the initial step in the oxidative ionization process is the formation of an O2 -• adduct. On the other hand, under bona fide electrospray ionization (ESI) conditions, 1,4-hydroquinone generates predominantly an (M - 1) - ion. It is known that at sufficiently high capillary voltages, corona discharges begin to occur even in an ESI source. At lower ESI capillary voltages, deprotonation predominates; as the capillary voltage is raised, the abundance of O2 -• present in the plasma increases, and the source in turn increasingly behaves as a composite ESI/APCI source. While maintaining post-ionization ion activation to a minimum (to prevent fragmentation), and monitoring the relative intensities of the m/z 109 (due to deprotonation) and 108 (oxidative ionization) peaks recorded from 1,4-hydroquinone, a semiquantitative estimation of the APCI contribution to the overall ion-generation process can be obtained.

Ultrahigh vacuum and low-temperature cleaning of oxide surfaces using a low-concentration ozone beam

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

Pratt, A.; Department of Physics, University of York, Heslington, York YO10 5DD; Graziosi, P.

We present a novel method of delivering a low-concentration (<15%) ozone beam to an ultra-high vacuum environment for the purpose of cleaning and dosing experimental samples through oxidation processing. The system described is safe, low-cost, and practical and overcomes the limitations of ozone transport in the molecular flow environment of high or ultrahigh vacuum whilst circumventing the use of pure ozone gas which is potentially highly explosive. The effectiveness of this method in removing surface contamination is demonstrated through comparison of high-temperature annealing of a simple oxide (MgO) in ozone and oxygen environments as monitored using quadrupole mass spectroscopy andmore » Auger electron spectroscopy. Additionally, we demonstrate the potential of ozone for obtaining clean complex oxide surfaces without the need for high-temperature annealing which may significantly alter surface structure.« less

Diagnostics of RF magnetron sputtering plasma for synthesizing transparent conductive Indium-Zinc-Oxide film

NASA Astrophysics Data System (ADS)

Ohta, Takayuki; Inoue, Mari; Takota, Naoki; Ito, Masafumi; Higashijima, Yasuhiro; Kano, Hiroyuki; den, Shoji; Yamakawa, Koji; Hori, Masaru

2009-10-01

Transparent conductive Oxide film has been used as transparent conducting electrodes of optoelectronic devices such as flat panel display, solar cells, and so on. Indium-Zinc-Oxide (IZO) has been investigated as one of promising alternatives Indium Tin Oxide film, due to amorphous, no nodule and so on. In order to control a sputtering process with highly precise, RF magnetron sputtering plasma using IZO composite target was diagnosed by absorption and emission spectroscopy. We have developed a multi-micro hollow cathode lamp which can emit simultaneous multi-atomic lines for monitoring Zn and In densities simultaneously. Zn and In densities were measured to be 10^9 from 10^10 cm-3 at RF power from 40 to 100 W, pressure of 5Pa, and Ar flow rate of 300 sccm. The emission intensities of Zn, In, InO, and Ar were also observed.

Oxidative stress and adipocyte biology: focus on the role of AGEs.

PubMed

Boyer, Florence; Vidot, Jennifer Baraka; Dubourg, Alexis Guerin; Rondeau, Philippe; Essop, M Faadiel; Bourdon, Emmanuel

2015-01-01

Diabetes is a major health problem that is usually associated with obesity, together with hyperglycemia and increased advanced glycation endproducts (AGEs) formation. Elevated AGEs elicit severe downstream consequences via their binding to receptors of AGEs (RAGE). This includes oxidative stress and oxidative modifications of biological compounds together with heightened inflammation. For example, albumin (major circulating protein) undergoes increased glycoxidation with diabetes and may represent an important biomarker for monitoring diabetic pathophysiology. Despite the central role of adipose tissue in many physiologic/pathologic processes, recognition of the effects of greater AGEs formation in this tissue is quite recent within the obesity/diabetes context. This review provides a brief background of AGEs formation and adipose tissue biology and thereafter discusses the impact of AGEs-adipocyte interactions in pathology progression. Novel data are included showing how AGEs (especially glycated albumin) may be involved in hyperglycemia-induced oxidative damage in adipocytes and its potential links to diabetes progression.

Optical conductivity of partially oxidized graphene from first principles

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

Nasehnia, F., E-mail: f.nasehnia@gmail.com; Seifi, M., E-mail: Seifi@guilan.ac.ir

2015-07-07

We investigate the geometry, electronic structure, and optical properties of partially oxidized graphene using density functional theory. Our calculations show that oxygen atoms are chemisorbed on graphene plane and distort carbon atoms vertically, with almost no change in the in-plane structure. The ground state configurations for different oxygen coverages ranging from 2% to 50% (O/C ratio) are calculated and show the strong tendency of oxygen adatoms to aggregate and form discrete islands on graphene plane. It is found that the opened band gap due to oxygen functionalization depends on the oxygen density and the adsorption configuration. The gap is notmore » significant for oxygen densities lower than 8%. The optical conductivities are calculated in the infrared, visible, and ultraviolet regions and show different characteristic features depending on the degree of oxidation. These results imply that optical measurement techniques can be employed to monitor oxidation (or reduction) process as contact-free methods.« less

Influence of in line monitored fluid bed granulation process parameters on the stability of Ethinylestradiol.

PubMed

Roßteuscher-Carl, Katrin; Fricke, Sabine; Hacker, Michael C; Schulz-Siegmund, Michaela

2015-12-30

Ethinylestradiol (EE) as a highly active and low dosed compound is prone to oxidative degradation. The stability of the drug substance is therefore a critical parameter that has to be considered during drug formulation. Beside the stability of the drug substance, granule particle size and moisture are critical quality attributes (CQA) of the fluid bed granulation process which influence the tableting ability of the resulting granules. Both CQA should therefore be monitored during the production process by process analytic technology (PAT) according to ICH Q8. This work focusses on the effects of drying conditions on the stability of EE in a fluid-bed granulation process. We quantified EE degradation products 6-alpha-hydroxy-EE, 6-beta-hydroxy-EE, 9(11)-dehydro-EE and 6-oxo-EE during long time storage and accelerated conditions. PAT-tools that monitor granule particle size (Spatial filtering technology) and granule moisture (Microwave resonance technology) were applied and compared with off-line methods. We found a relevant influence of residual granule moisture and thermic stress applied during granulation on the storage stability of EE, whereas no degradation was found immediately after processing. Hence we conclude that drying parameters have a relevant influence on long term EE stability. Copyright © 2015 Elsevier B.V. All rights reserved.

Interdisciplinary study of atmospheric processes and constituents of the mid-Atlantic coastal region. Attachment 5: Data set for background investigation of atmospheric constituents for Richmond, Virginia area. [air pollution monitoring

NASA Technical Reports Server (NTRS)

Kindle, E. C.; Bandy, A.; Copeland, G.; Blais, R.; Levy, G.; Sonenshine, D.; Adams, D.; Maier, G.

1975-01-01

Background data is provided for the photochemical oxident problem in the Richmond area. Particulate data, digitized portrayal of site molecular and meteorological data, and graphical portrayal of molecular data, hourly meteorological data, and streamflow charts and radiosonde data are also given.

Tracking and quantification of nitrifying bacteria in biofilm and mixed liquor of a partial nitrification MBBR pilot plant using fluorescence in situ hybridization.

PubMed

Abzazou, Tarik; Araujo, Rosa M; Auset, María; Salvadó, Humbert

2016-01-15

A moving bead biofilm reactor (MBBR) pilot plant was implemented as a partial nitrification process for pre-treatment of ammonium-rich liquors (676 ± 195 mg L(-1)), and studied for 479 days under variations in hydraulic retention time. The main purpose of this work, was the study of dynamics abundance of total bacteria and single-cells nitrifying bacteria belonging to ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) in biofilms and mixed liquor of the plant. The microbial monitoring was successfully achieved using fluorescence in situ hybridization combined with flocs disaggregation protocol as a useful microbial monitoring tool. A partial nitrification process with a N-NH4(+) removal rate of about 38.6 ± 14.8% was successfully achieved at 211 days after start-up, with a clear dominance of AOB, which accounted for 11.3 ± 17.0% of total bacterial cells compared with only 2.1 ± 4.0% of NOB. The effluent obtained was subsequently supplied to an Anammox reactor for complete ammonium treatment. Copyright © 2015 Elsevier B.V. All rights reserved.

Microfluidic Channels on Nanopatterned Substrates: Monitoring Protein Binding to Lipid Bilayers with Surface-Enhanced Raman Spectroscopy

PubMed Central

Banerjee, Amrita; Perez-Castillejos, R.; Hahn, D.; Smirnov, Alex I.; Grebel, H.

2013-01-01

We used Surface Enhanced Raman Spectroscopy (SERS) to detect binding events between streptavidin and biotinylated lipid bilayers. The binding events took place at the surface between microfluidic channels and anodized aluminum oxide (AAO) with the latter serving as substrates. The bilayers were incorporated in the substrate pores. It was revealed that non-bound molecules were easily washed away and that large suspended cells (Salmonella enterica) are less likely to interfere with the monitoring process: when focusing to the lower surface of the channel, one may resolve mostly the bound molecules. PMID:24932024

Micro-fluidic channels on nanopatterned substrates: Monitoring protein binding to lipid bilayers with surface-enhanced Raman spectroscopy

NASA Astrophysics Data System (ADS)

Banerjee, Amrita; Perez-Castillejos, R.; Hahn, D.; Smirnov, Alex I.; Grebel, H.

2010-04-01

We used surface-enhanced Raman spectroscopy (SERS) to detect binding events between streptavidin and biotinylated lipid bilayers. The binding events took place at the surface between micro-fluidic channels and anodized aluminum oxide (AAO) with the latter serving as substrates. The bilayers were incorporated in the substrate pores. It was revealed that non-bound molecules were easily washed away and that large suspended cells ( Salmonella enterica) are less likely to interfere with the monitoring process: when focusing to the lower surface of the channel, one may resolve mostly the bound molecules.

Randomized controlled study of the safety and efficacy of nitrous oxide-sedated endoscopic ultrasound-guided fine needle aspiration for digestive tract diseases

PubMed Central

Wang, Cai-Xia; Wang, Jian; Chen, Yuan-Yuan; Wang, Jia-Ni; Yu, Xin; Yang, Feng; Sun, Si-Yu

2016-01-01

AIM To evaluate the efficacy and safety of nitrous oxide-sedated endoscopic ultrasound-guided fine needle aspiration. METHODS Enrolled patients were divided randomly into an experimental group (inhalation of nitrous oxide) and a control group (inhalation of pure oxygen) and heart rate, blood oxygen saturation, blood pressure, electrocardiogram (ECG) changes, and the occurrence of complications were monitored and recorded. All patients and physicians completed satisfaction questionnaires about the examination and scored the process using a visual analog scale. RESULTS There was no significant difference in heart rate, blood oxygen saturation, blood pressure, ECG changes, or complication rate between the two groups of patients (P > 0.05). However, patient and physician satisfaction were both significantly higher in the nitrous oxide compared with the control group (P < 0.05). CONCLUSION Nitrous oxide-sedation is a safe and effective option for patients undergoing endoscopic ultrasound-guided fine needle aspiration. PMID:28028373

Novel Carbon Dioxide Microsensor Based on Tin Oxide Nanomaterial Doped With Copper Oxide

NASA Technical Reports Server (NTRS)

Xu, Jennifer C.; Hunter, Gary W.; Lukco, Dorothy; Liu, Chung-Chiun; Ward, Benjamin J.

2008-01-01

Carbon dioxide (CO2) is one of the major indicators of fire and therefore its measurement is very important for low-false-alarm fire detection and emissions monitoring. However, only a limited number of CO2 sensing materials exist due to the high chemical stability of CO2. In this work, a novel CO2 microsensor based on nanocrystalline tin oxide (SnO2) doped with copper oxide (CuO) has been successfully demonstrated. The CuO-SnO2 based CO2 microsensors are fabricated by means of microelectromechanical systems (MEMS) technology and sol-gel nanomaterial-synthesis processes. At a doping level of CuO: SnO2 = 1:8 (molar ratio), the resistance of the sensor has a linear response to CO2 concentrations for the range of 1 to 4 percent CO2 in air at 450 C. This approach has demonstrated the use of SnO2, typically used for the detection of reducing gases, in the detection of an oxidizing gas.

In vivo optical imaging of dihydroethidium oxidation in the mouse brain employing fluorescence intensity and lifetime contrast

NASA Astrophysics Data System (ADS)

Hall, David J.; Han, Sung-Ho; Dugan, Laura

2009-02-01

Reactive oxygen species (ROS) are believed to be involved in many diseases and injuries to the brain, but the molecular processes are not well understood due to a lack of in vivo imaging techniques to evaluate ROS. The fluorescent oxidation products of dihydroethidium (DHE) can monitor ROS production in vivo. Here we demonstrate the novel optical imaging of brain in live mice to measure ROS production via generation of fluorescent DHE oxidation products (ox-DHE) by ROS. We show that in Sod2+/- mice, which have partial loss of a key antioxidant enzyme, superoxide dismutase-2, that ox-DHE fluorescence intensity was significantly higher than in hSOD1 mice, which have four-fold overexpression of superoxide dismutase-1 activity, which had almost no ox-DHE fluorescence, confirming specificity of ox-DHE to ROS production. The DHE oxidation products were also confirmed by detecting a characteristic fluorescence lifetime of the oxidation product, which was validated with ex vivo measurements.

In Situ Infrared Spectroscopy of Oligoaniline Intermediates Created under Alkaline Conditions.

PubMed

Šeděnková, Ivana; Stejskal, Jaroslav; Trchová, Miroslava

2014-12-26

The progress of the oxidation of aniline with ammonium peroxydisulfate in an alkaline aqueous medium has been monitored in situ by attenuated total reflection (ATR) Fourier transform infrared spectroscopy. The growth of the microspheres and of the film at the ATR crystal surface, as well as the changes proceeding in the surrounding aqueous medium, are reflected in the spectra. The evolution of the spectra and the changes in the molecular structure occurring during aniline oxidation in alkaline medium are discussed with the help of differential spectra. Several processes connected with the various stages of aniline oxidation were distinguished. The progress of hydrolysis of the aniline in water and further an oxidation of aminophenol to benzoquinone imines in the presence of peroxydisulfate in alkaline medium have been detected in the spectra in real time. The precipitated solid oxidation product was analyzed by mass spectrometry. It is composed of oligomers, mainly trimers to octamers, of various molecular structures incorporating in addition to aniline constitutional units also p-benzoquinone or p-benzoquinoneimine moieties.

Composites based on PET and red mud residues as catalyst for organic removal from water.

PubMed

Bento, Natálya I; Santos, Patrícia S C; de Souza, Talita E; Oliveira, Luiz C A; Castro, Cínthia S

2016-08-15

In this study, we obtained a composite based on carbon/iron oxide from red mud and PET (poly(ethylene terephthalate)) wastes by mechanical mixture (10, 15 and 20wt.% of PET powder/red mud) followed by a controlled thermal treatment at 400°C under air. XRD analyses revealed that the α-Fe2O3 is the main phase formed from red mud. TPR analyses showed that the iron oxide present in the composites undergoes reduction at lower temperature to form Fe(2+) species present in Fe3O4, indicating that the iron oxide in the composite can exhibit greater reactivity in the catalytic processes compared to the original red mud. In fact, catalytic tests showed that the composites presented higher capacity to remove methylene blue dye (MB), presenting about 90% of removal after 24h of reaction. The MB removal was also monitored by mass spectrometer with ionization via electrospray (ESI-MS), which demonstrated the occurrence of the oxidation process, showing the formation of MB oxidation products. The stability of the composites was confirmed after four reuse cycles. The results seem to indicate that PET carbon deposited over the iron oxide from red mud promotes adsorption of the contaminant allowing its contact with the iron atoms and their consequent reaction. Copyright © 2016 Elsevier B.V. All rights reserved.

Quantitative methylene blue decolourisation assays as rapid screening tools for assessing the efficiency of catalytic reactions.

PubMed

Kruid, Jan; Fogel, Ronen; Limson, Janice Leigh

2017-05-01

Identifying the most efficient oxidation process to achieve maximum removal of a target pollutant compound forms the subject of much research. There exists a need to develop rapid screening tools to support research in this area. In this work we report on the development of a quantitative assay as a means for identifying catalysts capable of decolourising methylene blue through the generation of oxidising species from hydrogen peroxide. Here, a previously described methylene blue test strip method was repurposed as a quantitative, aqueous-based spectrophotometric assay. From amongst a selection of metal salts and metallophthalocyanine complexes, monitoring of the decolourisation of the cationic dye methylene blue (via Fenton-like and non-Fenton oxidation reactions) by the assay identified the following to be suitable oxidation catalysts: CuSO 4 (a Fenton-like catalyst), iron(II)phthalocyanine (a non-Fenton oxidation catalyst), as well as manganese(II) phthalocyanine. The applicability of the method was examined for the removal of bisphenol A (BPA), as measured by HPLC, during parallel oxidation experiments. The order of catalytic activity was identified as FePc > MnPc > CuSO 4 for both BPA and MB. The quantitative MB decolourisation assay may offer a rapid method for screening a wide range of potential catalysts for oxidation processes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Things fall apart: Fragmentation reactions in the oxidative aging of organic species

NASA Astrophysics Data System (ADS)

Kroll, J. H.; Isaacman-VanWertz, G. A.; Wilson, K. R.; Daumit, K. E.; Kessler, S. H.; Lim, C. Y.; Worsnop, D. R.

2016-12-01

The atmospheric oxidation of organic compounds involves a wide array of chemical transformations, including functionalization reactions (addition of polar functional groups to the carbon skeleton), fragmentation reactions (formation of lower carbon-number products via C-C bond scission), and accretion reactions (increases in molecular weight by the combination of two chemical species). Each of these reaction classes can lead to large changes in volatility, and hence can have major implications for atmospheric organic aerosol (OA). For example, the formation of OA is predominantly driven by functionalization and accretion reactions, which generally lead to decreases in volatility. Here we describe a series of laboratory studies of the subsequent organic "aging", the multiday oxidation processes that occur after the initial OA formation and growth. In these studies, the multigenerational oxidation of organic compounds in various phases (the gas phase, the condensed OA phase, and the aqueous phase) is carried out within either an environmental chamber or a flow reactor, and monitored using various high-resolution mass spectrometric techniques. In all cases it is found that fragmentation reactions play a major role in the observed aging chemistry, dominated by the formation of small, volatile oxidation products. These results suggest that multi-day oxidative aging processes do not lead to sustained aerosol growth, but rather may serve as a chemical sink for atmospheric OA.

Effect of soybean lecithin on iron-catalyzed or chlorophyll-photosensitized oxidation of canola oil emulsion.

PubMed

Choe, Jeesu; Oh, Boyoung; Choe, Eunok

2014-11-01

The effect of soybean lecithin addition on the iron-catalyzed or chlorophyll-photosensitized oxidation of emulsions consisting of purified canola oil and water (1:1, w/w) was studied based on headspace oxygen consumption using gas chromatography and hydroperoxide production using the ferric thiocyanate method. Addition levels of iron sulfate, chlorophyll, and soybean lecithin were 5, 4, and 350 mg/kg, respectively. Phospholipids (PLs) during oxidation of the emulsions were monitored by high performance liquid chromatography. Addition of soybean lecithin to the emulsions significantly reduced and decelerated iron-catalyzed oil oxidation by lowering headspace oxygen consumption and hydroperoxide production. However, soybean lecithin had no significant antioxidant effect on chlorophyll-photosensitized oxidation of the emulsions. PLs in soybean lecithin added to the emulsions were degraded during both oxidation processes, although there was little change in PL composition. Among PLs in soybean lecithin, phosphatidylethanolamine and phosphatidylinositol were degraded the fastest in the iron-catalyzed and the chlorophyll-photosensitized oxidation, respectively. The results suggest that addition of soybean lecithin as an emulsifier can also improve the oxidative stability of oil in an emulsion. © 2014 Institute of Food Technologists®

Optical sensor for real-time weld defect detection

NASA Astrophysics Data System (ADS)

Ancona, Antonio; Maggipinto, Tommaso; Spagnolo, Vincenzo; Ferrara, Michele; Lugara, Pietro M.

2002-04-01

In this work we present an innovative optical sensor for on- line and non-intrusive welding process monitoring. It is based on the spectroscopic analysis of the optical VIS emission of the welding plasma plume generated in the laser- metal interaction zone. Plasma electron temperature has been measured for different chemical species composing the plume. Temperature signal evolution has been recorded and analyzed during several CO2-laser welding processes, under variable operating conditions. We have developed a suitable software able to real time detect a wide range of weld defects like crater formation, lack of fusion, excessive penetration, seam oxidation. The same spectroscopic approach has been applied for electric arc welding process monitoring. We assembled our optical sensor in a torch for manual Gas Tungsten Arc Welding procedures and tested the prototype in a manufacturing industry production line. Even in this case we found a clear correlation between the signal behavior and the welded joint quality.

Microbial quantification in activated sludge: the hits and misses.

PubMed

Hall, S J; Keller, J; Blackall, L L

2003-01-01

Since the implementation of the activated sludge process for treating wastewater, there has been a reliance on chemical and physical parameters to monitor the system. However, in biological nutrient removal (BNR) processes, the microorganisms responsible for some of the transformations should be used to monitor the processes with the overall goal to achieve better treatment performance. The development of in situ identification and rapid quantification techniques for key microorganisms involved in BNR are required to achieve this goal. This study explored the quantification of Nitrospira, a key organism in the oxidation of nitrite to nitrate in BNR. Two molecular genetic microbial quantification techniques were evaluated: real-time polymerase chain reaction (PCR) and fluorescence in situ hybridisation (FISH) followed by digital image analysis. A correlation between the Nitrospira quantitative data and the nitrate production rate, determined in batch tests, was attempted. The disadvantages and advantages of both methods will be discussed.

Autofluorescence of human cells in vitro as a biomarker of their metabolic activity

NASA Astrophysics Data System (ADS)

Dobrzyńska, Monika; Stepińska, Małgorzata; Lewandowski, Rafał; Gietka, Andrzej; Łapiński, Mariusz P.; Trafny, ElŻbieta A.

2016-12-01

Autofluorescence (AF) is the natural emission of light by intrinsic fluorophores. Oxidized mitochondrial flavins, lipofuscin and reduced nicotinamideadenine dinucleotide phosphate (NAD(P)H) are the main sources of the autofluorescence in cells upon excitation with visible light. The aim of the study was to investigate changes in the metabolism of four cell lines by monitoring their autofluorescence with a microplate reader. Autofluorescence intensities of cells were collected at two wavelengths for the excitation and fluorescence emission: for endogenous NAD(P)H at 366/450 nm, for the oxidized flavoproteins and lipofuscin at 460/540 nm. Human mesenchymal stem cells (hMSC), epithelial cells from mammary gland (MCF 10A), breast ductal carcinoma (T-47D) prostate carcinoma (DU-145) were observed daily for 16 days. The level of NAD(P)H autofluorescence did not differ among the cell lines investigated. The significant increase in oxidized flavoproteins fluorescence intensity was recorded for hMSC and ranged from 140 to 175% of control. During 28 days differentiation process, the NAD(P)H, FAD and lipofuscin fluorescence intensities were recorded every day, and the redox ratio was then calculated. The redox ratio gradually decreased during the last eight days of osteogenesis and adipogenesis. Therefore, in our opinion the NAD(P)H, FAD, and lipofuscin fluorescence emission at the wavelengths selected are the optimal parameters to be collected during the differentiation process in order to monitor the metabolism of hMSC undergoing structural and morphological changes.

V6O13 films by control of the oxidation state from aqueous precursor to crystalline phase.

PubMed

Peys, Nick; Ling, Yun; Dewulf, Daan; Gielis, Sven; De Dobbelaere, Christopher; Cuypers, Daniel; Adriaensens, Peter; Van Doorslaer, Sabine; De Gendt, Stefan; Hardy, An; Van Bael, Marlies K

2013-01-28

An aqueous deposition process for V(6)O(13) films is developed whereby the vanadium oxidation state is continuously controlled throughout the entire process. In the precursor stage, a controlled wet chemical reduction of the vanadium(V) source with oxalic acid is achieved and monitored by (51)Vanadium Nuclear Magnetic Resonance ((51)V-NMR) and Ultraviolet-Visible (UV-Vis) spectroscopy. The resulting vanadium(IV) species in the aqueous solution are identified as mononuclear citrato-oxovanadate(IV) complexes by Electron Paramagnetic Resonance (EPR) and Fourier Transform Infra-Red (FTIR) spectroscopy. This precursor is successfully employed for the deposition of uniform, thin films. The optimal deposition and annealing conditions for the formation of crystalline V(6)O(13), including the control of the vanadium oxidation state, are determined through an elaborate study of processing temperature and O(2) partial pressure. To ensure a sub 100 nm adjustable film thickness, a non-oxidative intermediate thermal treatment is carried out at the end of each deposition cycle, allowing maximal precursor decomposition while still avoiding V(IV) oxidation. The resulting surface hydrophilicity, indispensable for the homogeneous deposition of the next layer, is explained by an increased surface roughness and the increased availability of surface vanadyl groups. Crystalline V(6)O(13) with a preferential (002) orientation is obtained after a post deposition annealing in a 0.1% O(2) ambient for thin films with a thickness of 20 nm.

Quantification of Fatty Acid Oxidation Products Using On-line High Performance Liquid Chromatography Tandem Mass Spectrometry

PubMed Central

Levison, Bruce S.; Zhang, Renliang; Wang, Zeneng; Fu, Xiaoming; DiDonato, Joseph A.; Hazen, Stanley L.

2013-01-01

Oxidized fatty acids formed via lipid peroxidation are implicated in pathological processes such as inflammation and atherosclerosis. A number of methods may be used to detect specific oxidized fatty acids containing a single or multiple combinations of epoxide, hydroxyl, ketone and hydroperoxide moieties on varying carbon chain lengths from C8 up to C30. Some of these methods are nonspecific and their use in biological systems is fraught with difficulty. Measures of specific-oxidized fatty acid derivatives help in identifying oxidation pathways in pathological processes. We used liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC-MS/MS) as efficient, selective and sensitive methods for identifying and analyzing multiple specific fatty acid peroxidation products in human plasma and other biological matrices. We then distilled the essential components of a number of these analyses to provide an efficient protocol by which fatty acid oxidation products and their parent compounds can be determined. In this protocol, addition of synthetic internal standard to the sample, followed by base hydrolysis at elevated temperature, and liquid-liquid phase sample extraction with lighter than water solvents facilitates isolation of the oxidized fatty acid species. These species can be identified and accurately quantified using stable isotope dilution and multiple reaction monitoring. Use of a coupled multiplexed gradient HPLC system on the front end enables high-throughput chromatography and more efficient use of mass spectrometer time. PMID:23499838

Zinc stable isotope fractionation upon accelerated oxidative weathering of sulfidic mine waste.

PubMed

Matthies, R; Krahé, L; Blowes, D W

2014-07-15

Accelerated oxidative weathering in a reaction cell (ASTM D 5744 standard protocol) was performed over a 33 week period on well characterized, sulfidic mine waste from the Kidd Creek Cu-Zn volcanogenic massive sulfide deposit, Canada. The cell leachate was monitored for physicochemical parameters, ion concentrations and stable isotope ratios of zinc. Filtered zinc concentrations (<0.45 μm) in the leachate ranged between 4.5 mg L(-1) and 1.9 g L(-1)-potentially controlled by pH, mineral solubility kinetics and (de)sorption processes. The zinc stable isotope ratios varied mass-dependently within +0.1 and +0.52‰ relative to IRMM 3702, and were strongly dependent on the pH (rpH-d66Zn=0.65, p<0.005, n=31). At a pH below 5, zinc mobilization was governed by sphalerite oxidation and hydroxide dissolution-pointing to the isotope signature of sphalerite (+0.1 to +0.16‰). Desorption processes resulted in enrichment of (66)Zn in the leachate reaching a maximum offset of +0.32‰ compared to the proposed sphalerite isotope signature. Over a period characterized by pH=6.1 ± 0.6, isotope ratios were significantly more enriched in (66)Zn with an offset of ≈ 0.23‰ compared to sphalerite, suggesting that zinc release may have been derived from a second zinc source, such as carbonate minerals, which compose 8 wt.% of the tailings. This preliminary study confirms the benefit of applying zinc isotopes alongside standard monitoring parameters to track principal zinc sources and weathering processes in complex multi-phase matrices. Copyright © 2014 Elsevier B.V. All rights reserved.

Proton mediated control of biochemical reactions with bioelectronic pH modulation

DOE PAGES

Deng, Yingxin; Miyake, Takeo; Keene, Scott; ...

2016-04-07

In Nature, protons (H +) can mediate metabolic process through enzymatic reactions. Examples include glucose oxidation with glucose dehydrogenase to regulate blood glucose level, alcohol dissolution into carboxylic acid through alcohol dehydrogenase, and voltage-regulated H + channels activating bioluminescence in firefly and jellyfish. Artificial devices that control H + currents and H + concentration (pH) are able to actively influence biochemical processes. Here, we demonstrate a biotransducer that monitors and actively regulates pH-responsive enzymatic reactions by monitoring and controlling the flow of H + between PdH x contacts and solution. The present transducer records bistable pH modulation from an “enzymaticmore » flip-flop” circuit that comprises glucose dehydrogenase and alcohol dehydrogenase. Furthermore, the transducer also controls bioluminescence from firefly luciferase by affecting solution pH.« less

Proton mediated control of biochemical reactions with bioelectronic pH modulation

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

Deng, Yingxin; Miyake, Takeo; Keene, Scott

In Nature, protons (H +) can mediate metabolic process through enzymatic reactions. Examples include glucose oxidation with glucose dehydrogenase to regulate blood glucose level, alcohol dissolution into carboxylic acid through alcohol dehydrogenase, and voltage-regulated H + channels activating bioluminescence in firefly and jellyfish. Artificial devices that control H + currents and H + concentration (pH) are able to actively influence biochemical processes. Here, we demonstrate a biotransducer that monitors and actively regulates pH-responsive enzymatic reactions by monitoring and controlling the flow of H + between PdH x contacts and solution. The present transducer records bistable pH modulation from an “enzymaticmore » flip-flop” circuit that comprises glucose dehydrogenase and alcohol dehydrogenase. Furthermore, the transducer also controls bioluminescence from firefly luciferase by affecting solution pH.« less

Analyzing workplace exposures using direct reading instruments and video exposure monitoring techniques

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

Gressel, M.G.; Heitbrink, W.A.; Jensen, P.A.

1992-08-01

The techniques for conducting video exposure monitoring were described along with the equipment required to monitor and record worker breathing zone concentrations, the analysis of the real time exposure data using video recordings, and the use of real time concentration data from a direct reading instrument to determine the effective ventilation rate and the mixing factor of a given room at a specific time. Case studies which made use of video exposure monitoring techniques to provide information not available through integrated sampling were also discussed. The process being monitored and the methodology used to monitor the exposures were described formore » each of the case studies. The case studies included manual material weigh out, ceramic casting cleaning, dumping bags of powdered materials, furniture stripping, administration of nitrous-oxide during dental procedures, hand held sanding operation, methanol exposures in maintenance garages, brake servicing, bulk loading of railroad cars and trucks, and grinding operations.« less

Metal-Catalyzed Aqueous Oxidation Processes in Merged Microdroplets

NASA Astrophysics Data System (ADS)

Davis, R. D.; Wilson, K. R.

2017-12-01

Iron-catalyzed production of reactive oxygen species (ROS) from hydrogen peroxide (Fenton's reaction) is a fundamental process throughout nature, from groundwater to cloud droplets. In recent years, Fenton's chemistry has gained further interest in atmospheric science as a potentially important process in the oxidation of aqueous secondary organic aerosol (e.g., Chu et al., Sci. Rep., 2017), with some observations indicating that Fenton's reaction proceeds at a higher rate at aerosol interfaces compared to in the bulk (Enami et al., PNAS, 2014). However, a fundamental-level mechanistic understanding of this process remains elusive and the relative importance of interfacial versus bulk chemistry for aqueous organic processing via Fenton's has yet to be fully established. Here, we present a microreactor experimental approach to studying aqueous-phase Fenton's chemistry in microdroplets by rapidly mixing droplets of different composition. Utilizing two on-demand droplet generators, a stream of microdroplets containing aqueous iron chloride were merged with a separate stream of microdroplets containing aqueous hydrogen peroxide and a range of aromatic organic compounds, initiating ROS production and subsequent aqueous-phase oxidation reactions. Upon merging, mixing of the microdroplets occurred in submillisecond timescales, thus allowing the reaction progress to be monitored with high spatial and temporal resolution. For relatively large microreactor (droplet) sizes (50 µm diameter post-merging), the Fenton-initiated aqueous oxidation of aromatic organic compounds in merged microdroplets was consistent with bulk predictions with hydroxyl radicals as the ROS. The microdroplet-size dependence of this observation, along with the role of other ROS species produced from Fenton and Fenton-like processes, will be discussed in the context of relative importance to aqueous organic processing of atmospheric particles.

Synthesis of Mesoporous Metal Oxides by Structure Replication: Thermal Analysis of Metal Nitrates in Porous Carbon Matrices

PubMed Central

Weinberger, Christian; Roggenbuck, Jan; Hanss, Jan; Tiemann, Michael

2015-01-01

A variety of metal nitrates were filled into the pores of an ordered mesoporous CMK-3 carbon matrix by solution-based impregnation. Thermal conversion of the metal nitrates into the respective metal oxides, and subsequent removal of the carbon matrix by thermal combustion, provides a versatile means to prepare mesoporous metal oxides (so-called nanocasting). This study aims to monitor the thermally induced processes by thermogravimetric analysis (TGA), coupled with mass ion detection (MS). The highly dispersed metal nitrates in the pores of the carbon matrix tend to react to the respective metal oxides at lower temperature than reported in the literature for pure, i.e., carbon-free, metal nitrates. The subsequent thermal combustion of the CMK-3 carbon matrix also occurs at lower temperature, which is explained by a catalytic effect of the metal oxides present in the pores. This catalytic effect is particularly strong for oxides of redox active metals, such as transition group VII and VIII metals (Mn, Fe, Co, Ni), Cu, and Ce. PMID:28347073

Effect of cross-linking of interfacial sodium caseinate by natural processing on the oxidative stability of oil-in-water (o/w) emulsions.

PubMed

Phoon, Pui Yeu; Paul, Lake N; Burgner, John W; San Martin-Gonzalez, M Fernanda; Narsimhan, Ganesan

2014-04-02

This study investigated how enzymatic cross-linking of interfacial sodium caseinate and emulsification, via high-pressure homogenization, influenced the intrinsic oxidative stability of 4% (w/v) menhaden oil-in-water emulsions stabilized by 1% (w/v) caseinate at pH 7. Oil oxidation was monitored by the ferric thiocyanate perioxide value assay. Higher homogenization pressure resulted in improved intrinsic emulsion oxidative stability, which is attributed to increased interfacial cross-linking as indicated by higher weighted average sedimentation coefficients of interfacial protein species (from 11.2 S for 0 kpsi/0.1 MPa to 18 S for 20 kpsi/137.9 MPa). Moderate dosage of transglutaminase at 0.5-1.0 U/mL emulsion enhanced intrinsic emulsion oxidative stability further, despite a contradictory reduction in the antioxidant property of cross-linked caseinate as tested by the 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay. This implied the prominent role of cross-linked interfacial caseinate as a physical barrier for oxygen transfer, hence its efficacy in retarding oil oxidation.

4-chlorophenol removal from water using graphite and graphene oxides as photocatalysts.

PubMed

Bustos-Ramírez, Karina; Barrera-Díaz, Carlos Eduardo; De Icaza-Herrera, Miguel; Martínez-Hernández, Ana Laura; Natividad-Rangel, Reyna; Velasco-Santos, Carlos

2015-01-01

Graphite and graphene oxides have been studied amply in the last decade, due to their diverse properties and possible applications. Recently, their functionality as photocatalytic materials in water splitting was reported. Research in these materials is increasing due to their band gap values around 1.8-4 eV, and therefore, these are comparable with other photocatalysts currently used in heterogeneous photocatalytic processes. Thus, this research reports the photocatalytic effectiveness of graphite oxide (GO) and graphene oxide (GEO) in the degradation of 4-chlorophenol (4-CP) in water. Under the conditions defined for this research, 92 and 97% of 4-CP were degraded with GO and GEO respectively, also 97% of total organic carbon was removed. In addition, by-products of 4-CP that produce a yellow solution obtained only using photolysis are eliminated by photocatalyst process with GO and GEO. The degradation of 4-CP was monitored by UV-Vis spectroscopy, High Performance Liquid Chromatography (HPLC) and Chemical Oxygen Demand (COD). Thus, photocatalytic activity to remove 4-CP from water employing GO and GEO without doping is successfully showed, and therefore, a new gate in research for these materials is opened.

Monitoring Intracellular Redox Changes in Ozone-exposed airway epithelial cells

EPA Science Inventory

Background: The toxicity of many compounds involves oxidative injury to cells. Direct assessment of mechanistic events involved in xenobiotic-induced oxidative stress is not easily achievable. Development of genetically-encoded probes designed for monitoring intracellular redox s...

Walk-through survey report: Control technology for integrated circuit fabrication, Xerox Corporation, El Segundo, California

NASA Astrophysics Data System (ADS)

Mihlan, G. J.; Ungers, L. J.; Smith, R. K.; Mitchell, R. I.; Jones, J. H.

1983-05-01

A preliminary control technology assessment survey was conducted at the facility which manufactures N-channel metal oxide semiconductor (NMOS) integrated circuits. The facility has industrial hygiene review procedures for evaluating all new and existing process equipment. Employees are trained in safety, use of personal protective equipment, and emergency response. Workers potentially exposed to arsenic are monitored for urinary arsenic levels. The facility should be considered a candidate for detailed study based on the diversity of process operations encountered and the use of state-of-the-art technology and process equipment.

High resolution and comprehensive techniques to analyze aerobic methane oxidation in mesocosm experiments

NASA Astrophysics Data System (ADS)

Chan, E. W.; Kessler, J. D.; Redmond, M. C.; Shiller, A. M.; Arrington, E. C.; Valentine, D. L.; Colombo, F.

2015-12-01

Many studies of microbially mediated aerobic methane oxidation in oceanic environments have examined the many different factors that control the rates of oxidation. However, there is debate on how quickly methane is oxidized once a microbial population is established and what factor(s) are limiting in these types of environments. These factors include the availability of CH4, O2, trace metals, nutrients, and the density of cell population. Limits to these factors can also control the temporal aspects of a methane oxidation event. In order to look at this process in its entirety and with higher temporal resolution, a mesocosm incubation system was developed with a Dissolved Gas Analyzer System (DGAS) coupled with a set of analytical tools to monitor aerobic methane oxidation in real time. With the addition of newer laser spectroscopy techniques (cavity ringdown spectroscopy), stable isotope fractionation caused by microbial processes can also be examined on a real time and automated basis. Cell counting, trace metal, nutrient, and DNA community analyses have also been carried out in conjunction with these mesocosm samples to provide a clear understanding of the biology in methane oxidation dynamics. This poster will detail the techniques involved to provide insights into the chemical and isotopic kinetics controlling aerobic methane oxidation. Proof of concept applications will be presented from seep sites in the Hudson Canyon and the Sleeping Dragon seep field, Mississippi Canyon 118 (MC 118). This system was used to conduct mesocosm experiments to examine methane consumption, O2 consumption, nutrient consumption, and biomass production.

[Methodological aspects of evaluation of potential lipid capacity for peroxidation from the serum levels of TBA-active products during iron ion stimulation].

PubMed

Kulikova, A I; Tugusheva, F A; Zubina, I M; Shepilova, I N

2008-05-01

The authors propose a simple and reproducible procedure for using iron ions to stimulate serum lipid peroxidation, with TBA-active products being further determined. The procedure determines the reserve of lipids that can be oxidized during oxidative stress. A combination of direct studies and correlation analysis suggests that low-density lipoproteins and very low-density lipoproteins are the major substrates for lipid peroxidation while high-density lipoproteins show a high resistance to this process. The presented procedure may be used to monitor lipid peroxidation in various conditions and upon various exposures in common laboratory practice.

Applications of fourier transform infrared spectroscopy to surface analysis problems 2

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

Powell, G.L.; Milosevic, M.

Applications of infrared spectroscopy to surface analysis are described in terms of the combined use of a number of techniques to solve specific surface analysis problems involving both qualitative and quantitative analysis of surface species. Emphasis is placed on the characterization of both the substrate and the surface species and the application of this to the monitoring of surface processes and the inspection of manufactured items. Lithium Hydride has been studied using remote analysis by diffuse reflectance in glove boxes containing very pure argon or controlled moisture levels with robot-operated gravimetric monitoring. These experiments are supported by internal reflectance andmore » diffuse reflectance measurements in spectrometer sample compartments to characterize the reactants. Beryllium oxide has been studied using an evacuable diffuse reflectance cell to determine the effects of vacuum baking reexposure to moisture on the surface hydroxyl species. Diffuse reflectance and emission measurements have been used to monitor the curing and reaction of environmental gases with composite materials such as graphite-expoxy structures. A direct comparison of diffuse reflectance and emission spectra was done using a barrel ellipsoid diffuse reflectance/emission detector and Spectropus optical transfer system. Grazing-incidence external-reflectance with p-polarized light was used to study the oxidation in room air of polished uranium coupons. The absorption band at 570 cm{sup {minus}1} was used to monitor the extent of oxidation with a resolution of approximately one monolayer of UO{sub 2} and to distinguish the parabolic, linear, and breakaway corrosion domains. External reflectance is compared with diffuse reflectance as a method for stain analysis and for measuring the effects of H{sub 2}O in UO{sub 2} corrosion films.« less

Applications of fourier transform infrared spectroscopy to surface analysis problems 2. Revision 1

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

Powell, G.L.; Milosevic, M.

Applications of infrared spectroscopy to surface analysis are described in terms of the combined use of a number of techniques to solve specific surface analysis problems involving both qualitative and quantitative analysis of surface species. Emphasis is placed on the characterization of both the substrate and the surface species and the application of this to the monitoring of surface processes and the inspection of manufactured items. Lithium Hydride has been studied using remote analysis by diffuse reflectance in glove boxes containing very pure argon or controlled moisture levels with robot-operated gravimetric monitoring. These experiments are supported by internal reflectance andmore » diffuse reflectance measurements in spectrometer sample compartments to characterize the reactants. Beryllium oxide has been studied using an evacuable diffuse reflectance cell to determine the effects of vacuum baking reexposure to moisture on the surface hydroxyl species. Diffuse reflectance and emission measurements have been used to monitor the curing and reaction of environmental gases with composite materials such as graphite-expoxy structures. A direct comparison of diffuse reflectance and emission spectra was done using a barrel ellipsoid diffuse reflectance/emission detector and Spectropus optical transfer system. Grazing-incidence external-reflectance with p-polarized light was used to study the oxidation in room air of polished uranium coupons. The absorption band at 570 cm{sup {minus}1} was used to monitor the extent of oxidation with a resolution of approximately one monolayer of UO{sub 2} and to distinguish the parabolic, linear, and breakaway corrosion domains. External reflectance is compared with diffuse reflectance as a method for stain analysis and for measuring the effects of H{sub 2}O in UO{sub 2} corrosion films.« less

Development of on-line laser power monitoring system

NASA Astrophysics Data System (ADS)

Ding, Chien-Fang; Lee, Meng-Shiou; Li, Kuan-Ming

2016-03-01

Since the laser was invented, laser has been applied in many fields such as material processing, communication, measurement, biomedical engineering, defense industries and etc. Laser power is an important parameter in laser material processing, i.e. laser cutting, and laser drilling. However, the laser power is easily affected by the environment temperature, we tend to monitor the laser power status, ensuring there is an effective material processing. Besides, the response time of current laser power meters is too long, they cannot measure laser power accurately in a short time. To be more precisely, we can know the status of laser power and help us to achieve an effective material processing at the same time. To monitor the laser power, this study utilize a CMOS (Complementary metal-oxide-semiconductor) camera to develop an on-line laser power monitoring system. The CMOS camera captures images of incident laser beam after it is split and attenuated by beam splitter and neutral density filter. By comparing the average brightness of the beam spots and measurement results from laser power meter, laser power can be estimated. Under continuous measuring mode, the average measuring error is about 3%, and the response time is at least 3.6 second shorter than thermopile power meters; under trigger measuring mode which enables the CMOS camera to synchronize with intermittent laser output, the average measuring error is less than 3%, and the shortest response time is 20 millisecond.

Monitoring of In-Situ Remediation By Time Lapse 3D Geo-Electric Measurements

NASA Astrophysics Data System (ADS)

Kanli, A. I.; Tildy, P.; Neducza, B.; Nagy, P.; Hegymegi, C.

2017-12-01

Injection of chemical oxidant solution to degrade the subsurface contaminants can be used for hydrocarbon contamination remediation. In this study, we developed a non-destructive measurement strategy to monitor oxidative in-situ remediation processes. The difficulties of the presented study originate from the small volume of conductive solution that can be used due to environmental considerations. Due to the effect of conductive groundwater and the high clay content of the targeted layer and the small volume of conductive solution that can be used due to environmental considerations, a site specific synthetic modelling is necessary for measurement design involving the results of preliminary 2D ERT measurements, electrical conductivity measurements of different active agents and expected resistivity changes calculated by soil resistivity modelling. Because of chemical biodegradation, the results of soil resistivity modelling have suggested that the reagent have complex effects on contaminated soils. As a result the plume of resistivity changes caused by the injected agent was determined showing strong fracturing effect because of the high pressure of injection. 3D time-lapse geo-electric measurements were proven to provide a usable monitoring tool for in-situ remediation as a result of our sophisticated tests and synthetic modelling.

Freestanding, Fiber-Based, Wearable Temperature Sensor with Tunable Thermal Index for Healthcare Monitoring.

PubMed

Trung, Tran Quang; Le, Hoang Sinh; Dang, Thi My Linh; Ju, Sanghyun; Park, Sang Yoon; Lee, Nae-Eung

2018-06-01

Fiber-based sensors integrated on textiles or clothing systems are required for the next generation of wearable electronic platforms. Fiber-based physical sensors are developed, but the development of fiber-based temperature sensors is still limited. Herein, a new approach to develop wearable temperature sensors that use freestanding single reduction graphene oxide (rGO) fiber is proposed. A freestanding and wearable temperature-responsive rGO fiber with tunable thermal index is obtained using simple wet spinning and a controlled graphene oxide reduction time. The freestanding fiber-based temperature sensor shows high responsivity, fast response time (7 s), and good recovery time (20 s) to temperature. It also maintains its response under an applied mechanical deformation. The fiber device fabricated by means of a simple process is easily integrated into fabric such as socks or undershirts and can be worn by a person to monitor the temperature of the environment and skin temperature without interference during movement and various activities. These results demonstrate that the freestanding fiber-based temperature sensor has great potential for fiber-based wearable electronic platforms. It is also promising for applications in healthcare and biomedical monitoring. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation and Characterization of a Master Blend of Plutonium Oxide for the 3013 Large Scale Shelf-Life Surveillance Project

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

Gillispie, Obie William; Worl, Laura Ann; Veirs, Douglas Kirk

A mixture of chlorine-containing, impure plutonium oxides has been produced and has been given the name Master Blend. This large quantity of well-characterized chlorinecontaining material is available for use in the Integrated Surveillance and Monitoring Program for shelf-life experiments. It is intended to be representative of materials packaged to meet DOE-STD-3013.1 The Master Blend contains a mixture of items produced in Los Alamos National Laboratory’s (LANL) electro-refining pyrochemical process in the late 1990s. Twenty items were crushed and sieved, calcined to 800ºC for four hours, and blended multiple times. This process resulted in four batches of Master Blend. Calorimetry andmore » density data on material from the four batches indicate homogeneity.« less

Biological cycling of atmospheric trace gases

NASA Technical Reports Server (NTRS)

Hitchcock, D. R.; Wechsler, A. E.

1972-01-01

A detailed critical review was conducted of present knowledge of the influence of biological processes on the cycling of selected atmospheric gas constituents--methane, carbon monoxide, and gaseous compounds of nitrogen (nitrous oxide, ammonia, nitric oxide, and nitrogen dioxide) and sulfur (hydrogen sulfide and sulfur dioxide). The identification was included of biological and other sources of each gas, a survey of abundance measurements reported in the literature, and a review of the atmospheric fate of each contituent. Information is provided on which to base conclusions regarding the importance of biological processes on the atmospheric distribution and surface-atmosphere exchange of each constituent, and a basis for estimating the adequacy of present knowledge of these factors. A preliminary analysis was conducted of the feasibility of monitoring the biologically influenced temporal and spatial variations in abundance of these gases in the atmosphere from satellites.

Carbon aerogels by pyrolysis of TEMPO-oxidized cellulose

NASA Astrophysics Data System (ADS)

Zhang, Sizhao; Feng, Jian; Feng, Junzong; Jiang, Yonggang; Ding, Feng

2018-05-01

Although carbon aerogels derived from naturally occurring materials have been developed extensively, a reasonable synthetic approach using cellulose-resource remains unclear. Here, we report a strategy to prepare carbon aerogels originated from cellulose position-selectively oxidized by TEMPO-oxidized process. Contrary to non-TEMPO-oxidized cellulose-derived carbon aerogels (NCCA) with relative loose structure, TEMPO-oxidized cellulose-derived carbon aerogels (TCCA) with tight fibrillar-continuous network are monitored, suggesting the importance of TEMPO-oxidized modification towards creating the architecture of subsequently produced carbon aerogels. TCCA endows a higher BET area despite owning slightly dense bulk density comparing with that of NCCA. The structural texture of TCCA could be maintained in a way in comparison to TEMPO-oxidized cellulose-derived aerogel, due to the integration and aggregation effect by losing the electric double layer repulsion via ionization of the surface carboxyl groups. FTIR and XPS analyses signify the evidence of non-functionalized carbon-skeleton network formation in terms of TCCA. Further, the mechanism concerning the creation of carbon aerogels is also established. These findings not only provide new insights into the production of carbon aerogels but also open up a new opportunity in the field of functional carbon materials.

Monitoring automotive oil degradation: analytical tools and onboard sensing technologies.

PubMed

Mujahid, Adnan; Dickert, Franz L

2012-09-01

Engine oil experiences a number of thermal and oxidative phases that yield acidic products in the matrix consequently leading to degradation of the base oil. Generally, oil oxidation is a complex process and difficult to elucidate; however, the degradation pathways can be defined for almost every type of oil because they mainly depend on the mechanical status and operating conditions. The exact time of oil change is nonetheless difficult to predict, but it is of great interest from an economic and ecological point of view. In order to make a quick and accurate decision about oil changes, onboard assessment of oil quality is highly desirable. For this purpose, a variety of physical and chemical sensors have been proposed along with spectroscopic strategies. We present a critical review of all these approaches and of recent developments to analyze the exact lifetime of automotive engine oil. Apart from their potential for degradation monitoring, their limitations and future perspectives have also been investigated.

Impact of electrochemical treatment of soil washing solution on PAH degradation efficiency and soil respirometry.

PubMed

Mousset, Emmanuel; Huguenot, David; van Hullebusch, Eric D; Oturan, Nihal; Guibaud, Gilles; Esposito, Giovanni; Oturan, Mehmet A

2016-04-01

The remediation of a genuinely PAH-contaminated soil was performed, for the first time, through a new and complete investigation, including PAH extraction followed by advanced oxidation treatment of the washing solution and its recirculation, and an analysis of the impact of the PAH extraction on soil respirometry. The study has been performed on the remediation of genuine PAH-contaminated soil, in the following three steps: (i) PAH extraction with soil washing (SW) techniques, (ii) PAH degradation with an electro-Fenton (EF) process, and (iii) recirculation of the partially oxidized effluent for another SW cycle. The following criteria were monitored during the successive washing cycles: PAH extraction efficiency, PAH oxidation rates and yields, extracting agent recovery, soil microbial activity, and pH of soil. Two representative extracting agents were compared: hydroxypropyl-beta-cyclodextrin (HPCD) and a non-ionic surfactant, Tween(®) 80. Six PAH with different numbers of rings were monitored: acenaphthene (ACE), phenanthrene (PHE), fluoranthene (FLA), pyrene (PYR), benzo(a)pyrene (BaP), and benzo(g,h,i)perylene (BghiP). Tween(®) 80 showed much better PAH extraction efficiency (after several SW cycles) than HPCD, regardless of the number of washing cycles. Based on successive SW experiments, a new mathematical relation taking into account the soil/water partition coefficient (Kd*) was established, and could predict the amount of each PAH extracted by the surfactant with a good correlation with experimental results (R(2) > 0.975). More HPCD was recovered (89%) than Tween(®) 80 (79%), while the monitored pollutants were completely degraded (>99%) after 4 h and 8 h, respectively. Even after being washed with partially oxidized solutions, the Tween(®) 80 solutions extracted significantly more PAH than HPCD and promoted better soil microbial activity, with higher oxygen consumption rates. Moreover, neither the oxidation by-products nor the acidic media (pH approximately 3) of the partially oxidized solution inhibited the general soil microbial activity during the washing cycle. Copyright © 2016 Elsevier Ltd. All rights reserved.

The redox processes in Hg-contaminated soils from Descoberto (Minas Gerais, Brazil): implications for the mercury cycle.

PubMed

Windmöller, Cláudia C; Durão Júnior, Walter A; de Oliveira, Aline; do Valle, Cláudia M

2015-02-01

Investigations of the redox process and chemical speciation of Hg(II) lead to a better understanding of biogeochemical processes controlling the transformation of Hg(II) into toxic and bioaccumulative monomethyl mercury, mainly in areas contaminated with Hg(0). This study investigates the speciation and redox processes of Hg in soil samples from a small area contaminated with Hg(0) as a result of gold mining activities in the rural municipality of Descoberto (Minas Gerais, Brazil). Soil samples were prepared by adding Hg(0) and HgCl2 separately to dry soil, and the Hg redox process was monitored using thermodesorption coupled to atomic absorption spectrometry. A portion of the Hg(0) added was volatilized (up to 37.4±2.0%) or oxidized (from 36±7% to 88±16%). A correlation with Mn suggests that this oxidation is favored, but many other factors must be evaluated, such as the presence of microorganisms and the types of organic matter present. The interaction of Hg with the matrix is suggested to involve Hg(II)-complexes formed with inorganic and organic sulfur ligands and/or nonspecific adsorption onto oxides of Fe, Al and/or Mn. The kinetics of the oxidation reaction was approximated for two first-order reactions; the faster reaction was attributed to the oxidation of Hg(0)/Hg(I), and the slower reaction corresponded to Hg(I)/Hg(II). The second stage was 43-139 times slower than the first. The samples spiked with Hg(II) showed low volatilization and a shifting of the signal of Hg(II) to lower temperatures. These results show that the extent, rate and type of redox process can be adverse in soils. Descoberto can serve as an example for areas contaminated with Hg(0). Copyright © 2014 Elsevier Inc. All rights reserved.

Online monitoring of electrocatalytic reactions of alcohols at platinum and gold electrodes in acidic, neutral and alkaline media by capillary electrophoresis with contactless conductivity detection (EC-CE-C4 D).

PubMed

Ferreira Santos, Mauro Sérgio; Silva Lopes, Fernando; Gutz, Ivano Gebhardt Rolf

2017-11-01

An EC-CE-C 4 D flow system was applied to the investigation of electrocatalytic processes by monitoring carboxylic acids formed during the electro-oxidation at various potentials of primary alcohols (mixture of 1 mmol/L of ethanol, n-propanol, n-butanol and n-pentanol) in acidic, neutral and alkaline media. The electro-oxidation was carried out on gold and platinum disk electrodes (3 mm of diameter) in a thin-layer electrochemical flow cell. Products were sampled 50 μm apart from the electrode directly into the capillary. All the generated carboxylates were determined in near real time (less than 2 min) by CE-C 4 D in counter-flow mode, with Tris/HCl buffer solution (pH 8.6) as BGE. Long sequences of 5-min experiments were run automatically, exploring the applied potential, electrolysis time and solution composition. Electro-oxidation at 1.5 V (versus Ag/AgCl quasi-reference) during 50 s in acidic medium was found appropriate for both Pt and Au electrodes when the determination of alcohols after derivatization is intended. A noteworthy selectivity effect was observed on the Au electrode. The signal corresponding to pentanoate is similar on both electrodes while the signal of ethanoate (acetate) is four times larger on gold than on platinum. The carboxylate signals were lower in alkaline medium (below the determination limit on Pt) than in acidic and neutral media. On gold, the formation of carboxylates was anticipated (0.85 V in alkaline medium versus 1.40 V in neutral medium). The automatic online monitoring of electrochemical processes by EC-CE-C 4 D holds great potential to investigate ionic/ionizable intermediates/products of new electrocatalysts and/or alternative fuels. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optical Sensor for real-time Monitoring of CO(2) Laser Welding Process.

PubMed

Ancona, A; Spagnolo, V; Lugarà, P M; Ferrara, M

2001-11-20

An optical sensor for real-time monitoring of laser welding based on a spectroscopic study of the optical emission of plasma plumes has been developed. The welding plasma's electron temperature was contemporarily monitored for three of the chemical species that constitute the plasma plume by use of related emission lines. The evolution of electron temperature was recorded and analyzed during several welding procedures carried out under various operating conditions. A clear correlation between the mean value and the standard deviation of the plasma's electron temperature and the quality of the welded joint has been found. We used this information to find optimal welding parameters and for real-time detection of weld defects such as crater formation, lack of penetration, weld disruptions, and seam oxidation.

Long-term phenol, cresols and BTEX monitoring in urban air.

PubMed

Sturaro, Alberto; Rella, Rocco; Parvoli, Giorgio; Ferrara, Daniela

2010-05-01

This paper reports the results of a long-term monitoring of benzene, toluene, ethylbenzene, xylenes (BTEX), phenol and cresols in the air of Padua during a wide period of the year 2007 using two radial passive samplers (Radiello system) equipped with BTEX- and phenol-specific cartridges. Two sites were monitored, one in the industrial area and one close to the town centre. Relevant pollution episodes have been observed during both the winter and summer periods. Benzene, together with toluene, ethylbenzene and xylenes showed their maximum concentrations during the winter season, but the secondary pollutant phenol was higher than benzene for a large period of the year when the meteorological conditions blocked the pollutants in the lower layers of the atmosphere and solar radiation increased the benzene photo-oxidation process.

Quantitative 3D evolution of colloidal nanoparticle oxidation in solution

DOE PAGES

Sun, Yugang; Zuo, Xiaobing; Sankaranarayanan, Subramanian K. R. S.; ...

2017-04-21

Real-time tracking three-dimensional (3D) evolution of colloidal nanoparticles in solution is essential for understanding complex mechanisms involved in nanoparticle growth and transformation. We simultaneously use time-resolved small-angle and wide-angle x-ray scattering to monitor oxidation of highly uniform colloidal iron nanoparticles, enabling the reconstruction of intermediate 3D morphologies of the nanoparticles with a spatial resolution of ~5 Å. The in-situ probing combined with large-scale reactive molecular dynamics simulations reveals the transformational details from the solid metal nanoparticles to hollow metal oxide nanoshells via nanoscale Kirkendall process, for example, coalescence of voids upon their growth, reversing of mass diffusion direction depending onmore » crystallinity, and so forth. In conclusion, our results highlight the complex interplay between defect chemistry and defect dynamics in determining nanoparticle transformation and formation.« less

Nitric oxide (NO.) stabilizes whereas nitrosonium (NO+) enhances filopodial outgrowth by rat retinal ganglion cells in vitro.

PubMed

Cheung, W S; Bhan, I; Lipton, S A

2000-06-16

Recent observations suggest that nitric oxide (NO(.)) can increase or decrease growth cone motility. Here, these apparently paradoxical results are explained by distinct actions of different NO-related species. Filopodial morphology of 223 rat retinal ganglion cells was monitored under computer-enhanced video microscopy in the presence of NO synthase (NOS) substrates or inhibitors, donors of specific NO-related species, and membrane-permeant cyclic nucleotide analogs. Physiological NOS activity induced filopodial outgrowth, whereas inhibition of NOS stabilized filopodia. Similar to NOS, nitrosonium (NO(+) transfer) and peroxynitrite (ONOO(-)), which can regulate the activity of growth-associated proteins by S-nitrosylation and oxidation, respectively, induced filopodial outgrowth. In contrast, NO(.), which stimulates guanylate cyclase to increase cGMP, stabilized filopodial activity. Thus disparate NO-related species may offer a dynamic process of filopodial growth regulation.

Quantitative 3D evolution of colloidal nanoparticle oxidation in solution

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

Sun, Yugang; Zuo, Xiaobing; Sankaranarayanan, Subramanian K. R. S.

Real-time tracking three-dimensional (3D) evolution of colloidal nanoparticles in solution is essential for understanding complex mechanisms involved in nanoparticle growth and transformation. We simultaneously use time-resolved small-angle and wide-angle x-ray scattering to monitor oxidation of highly uniform colloidal iron nanoparticles, enabling the reconstruction of intermediate 3D morphologies of the nanoparticles with a spatial resolution of ~5 Å. The in-situ probing combined with large-scale reactive molecular dynamics simulations reveals the transformational details from the solid metal nanoparticles to hollow metal oxide nanoshells via nanoscale Kirkendall process, for example, coalescence of voids upon their growth, reversing of mass diffusion direction depending onmore » crystallinity, and so forth. In conclusion, our results highlight the complex interplay between defect chemistry and defect dynamics in determining nanoparticle transformation and formation.« less

Protein oxidative modifications during electrospray ionization: solution phase electrochemistry or corona discharge-induced radical attack?

PubMed

Boys, Brian L; Kuprowski, Mark C; Noël, James J; Konermann, Lars

2009-05-15

The exposure of solution-phase proteins to reactive oxygen species (ROS) causes oxidative modifications, giving rise to the formation of covalent +16 Da adducts. Electrospray ionization (ESI) mass spectrometry (MS) is the most widely used method for monitoring the extent of these modifications. Unfortunately, protein oxidation can also take place as an experimental artifact during ESI, such that it may be difficult to assess the actual level of oxidation in bulk solution. Previous work has demonstrated that ESI-induced oxidation is highly prevalent when operating at strongly elevated capillary voltage V(0) (e.g., +8 kV) and with oxygen nebulizer gas in the presence of a clearly visible corona discharge. Protein oxidation under these conditions is commonly attributed to OH radicals generated in the plasma of the discharge. On the other hand, charge balancing oxidation reactions are known to take place at the metal/liquid interface of the emitter. Previous studies have not systematically explored whether such electrochemical processes could be responsible for the formation of oxidative +16 Da adducts instead of (or in combination with) plasma-generated ROS. Using hemoglobin as a model system, this work illustrates the occurrence of extensive protein oxidation even under typical operating conditions (e.g., V(0) = 3.5 kV, N(2) nebulizer gas). Surprisingly, measurements of the current flowing in the ESI circuit demonstrate that a weak corona discharge persists for these relatively gentle settings. On the basis of comparative experiments with nebulizer gases of different dielectric strength, it is concluded that ROS generated under discharge conditions are solely responsible for ESI-induced protein oxidation. This result is corroborated through off-line electrolysis experiments designed to mimic the electrochemical processes taking place during ESI. Our findings highlight the necessity of using easily oxidizable internal standards in biophysical or biomedical ESI-MS studies where knowledge of protein oxidation in bulk solution is desired. Strategies for eliminating ESI-induced oxidation artifacts are discussed.

Recycling and Resistance of Petrogenic Particulate Organic Carbon: Implications from A Chemical Oxidation Method

NASA Astrophysics Data System (ADS)

Zhang, T.; Li, G.; Ji, J.

2013-12-01

Petrogenic particulate organic carbon (OCpetro) represents a small fraction of photosynthetic carbon which escapes pedogenic-petrogenic degradation and gets trapped in the lithosphere. Exhumation and recycling of OCpetro are of significant importance in the global carbon cycle because OCpetro oxidation represents a substantial carbon source to the atmosphere while the re-burial of OCpetro in sediment deposits has no net effect. Though studies have investigated various behaviors of OCpetro in the surface environments (e.g., riverine mobilization, marine deposition, and microbial remineralization), less attention has been paid to the reaction kinetics and structural transformations during OCpetro oxidation. Here we assess the OCpetro-oxidation process based on a chemical oxidation method adopted from soil studies. The employed chemical oxidation method is considered an effective simulation of natural oxidation in highly oxidative environments, and has been widely used in soil studies to isolate the inert soil carbon pool. We applied this chemical method to the OCpetro-enriched black shale samples from the middle-lower Yangtze (Changjiang) basin, China, and performed comprehensive instrumental analyses (element analysis, Fourier transform infrared (FTIR) spectrum, and Raman spectrum). We also conducted step-oxidizing experiments following fixed time series and monitored the reaction process in rigorously controlled lab conditions. In this work, we present our experiment results and discuss the implications for the recycling and properties of OCpetro. Particulate organic carbon concentration of black shale samples before and after oxidation helps to quantify the oxidability of OCpetro and constrain the preservation efficiency of OCpetro during fluvial erosion over large river basin scales. FTIR and Raman analyses reveal clear structural variations on atomic and molecular levels. Results from the step-oxidizing experiments provide detailed information about the reaction kinetics and allow differentiation of different components in OCpetro characterized by distinct reaction rates. All these results lead to a better understanding of OCpetro recycling in the surface environments, and furthermore, the role of OCpetro in the global carbon cycle.

Relation between film character and wafer alignment: critical alignment issues on HV device for VLSI manufacturing

NASA Astrophysics Data System (ADS)

Lo, Yi-Chuan; Lee, Chih-Hsiung; Lin, Hsun-Peng; Peng, Chiou-Shian

1998-06-01

Several continuous splits for wafer alignment target topography conditions to improve epitaxy film alignment were applied. The alignment evaluation among former layer pad oxide thickness (250 angstrom - 500 angstrom), drive oxide thickness (6000 angstrom - 10000 angstrom), nitride film thickness (600 angstrom - 1500 angstrom), initial oxide etch (fully wet etch, fully dry etch and dry plus wet etch) will be split to this experiment. Also various epitaxy deposition recipe such as: epitaxy source (SiHCl2 or SiCHCl3) and growth rate (1.3 micrometer/min approximately 2.0 micrometer/min) will be used to optimize the process window for alignment issue. All the reflectance signal and cross section photography of alignment target during NIKON stepper alignment process will be examined. Experimental results show epitaxy recipe plays an important role to wafer alignment. Low growth rate with good performance conformity epitaxy lead to alignment target avoid washout, pattern shift and distortion. All the results (signal monitor and film character) combined with NIKON's stepper standard laser scanning alignment system will be discussed in this paper.

New processes and materials for ultraviolet detection with solid state devices

NASA Technical Reports Server (NTRS)

Chopra, D.

1977-01-01

The three major effects that degrade external responsivity of silicon from the 1/lambda theoretical curve for a quantum detector are: surface reflectance, surface recombination, and junction depth. Since the p-n junction must be very shallow, problems relating to surface are further enhanced. MOS type of processing is necessary. HCl oxides and numerous acid clean-ups are utilized in order to obtain a contamination free surface with low Qss levels. Stringent process controls such as CV shifts, spreading resistance measurements, thickness monitoring etc., are used to analyze the surface contaminations, surface mobile charges, surface concentrations, junction depth, oxide thickness etc. Low surface concentrations of 10 to the 18th atoms/cu cm are achieved by low temperature boron nitride depositions. Shallow junction depths of the order of a few tenths of a micron are achieved by low temperature controlled diffusions. In order to improve breakdown characteristics of these shallow junction devices, field plate and deep diffused p(+) ring geometries are used.

Enhancing the far-ultraviolet sensitivity of silicon complementary metal oxide semiconductor imaging arrays

NASA Astrophysics Data System (ADS)

Retherford, Kurt D.; Bai, Yibin; Ryu, Kevin K.; Gregory, James A.; Welander, Paul B.; Davis, Michael W.; Greathouse, Thomas K.; Winters, Gregory S.; Suntharalingam, Vyshnavi; Beletic, James W.

2015-10-01

We report our progress toward optimizing backside-illuminated silicon P-type intrinsic N-type complementary metal oxide semiconductor devices developed by Teledyne Imaging Sensors (TIS) for far-ultraviolet (UV) planetary science applications. This project was motivated by initial measurements at Southwest Research Institute of the far-UV responsivity of backside-illuminated silicon PIN photodiode test structures, which revealed a promising QE in the 100 to 200 nm range. Our effort to advance the capabilities of thinned silicon wafers capitalizes on recent innovations in molecular beam epitaxy (MBE) doping processes. Key achievements to date include the following: (1) representative silicon test wafers were fabricated by TIS, and set up for MBE processing at MIT Lincoln Laboratory; (2) preliminary far-UV detector QE simulation runs were completed to aid MBE layer design; (3) detector fabrication was completed through the pre-MBE step; and (4) initial testing of the MBE doping process was performed on monitoring wafers, with detailed quality assessments.

In situ dynamic tracking of heterogeneous nanocatalytic processes by shell-isolated nanoparticle-enhanced Raman spectroscopy

PubMed Central

Zhang, Hua; Wang, Chen; Sun, Han-Lei; Fu, Gang; Chen, Shu; Zhang, Yue-Jiao; Chen, Bing-Hui; Anema, Jason R.; Yang, Zhi-Lin; Li, Jian-Feng; Tian, Zhong-Qun

2017-01-01

Surface molecular information acquired in situ from a catalytic process can greatly promote the rational design of highly efficient catalysts by revealing structure-activity relationships and reaction mechanisms. Raman spectroscopy can provide this rich structural information, but normal Raman is not sensitive enough to detect trace active species adsorbed on the surface of catalysts. Here we develop a general method for in situ monitoring of heterogeneous catalytic processes through shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) satellite nanocomposites (Au-core silica-shell nanocatalyst-satellite structures), which are stable and have extremely high surface Raman sensitivity. By combining operando SHINERS with density functional theory calculations, we identify the working mechanisms for CO oxidation over PtFe and Pd nanocatalysts, which are typical low- and high-temperature catalysts, respectively. Active species, such as surface oxides, superoxide/peroxide species and Pd–C/Pt–C bonds are directly observed during the reactions. We demonstrate that in situ SHINERS can provide a deep understanding of the fundamental concepts of catalysis. PMID:28537269

Design of anti- and pro-aggregation variants to assess the effects of methionine oxidation in human prion protein

PubMed Central

Wolschner, Christina; Giese, Armin; Kretzschmar, Hans A.; Huber, Robert; Moroder, Luis; Budisa, Nediljko

2009-01-01

Prion disease is characterized by the α→β structural conversion of the cellular prion protein (PrPC) into the misfolded and aggregated “scrapie” (PrPSc) isoform. It has been speculated that methionine (Met) oxidation in PrPC may have a special role in this process, but has not been detailed and assigned individually to the 9 Met residues of full-length, recombinant human PrPC [rhPrPC(23-231)]. To better understand this oxidative event in PrP aggregation, the extent of periodate-induced Met oxidation was monitored by electrospray ionization-MS and correlated with aggregation propensity. Also, the Met residues were replaced with isosteric and chemically stable, nonoxidizable analogs, i.e., with the more hydrophobic norleucine (Nle) and the highly hydrophilic methoxinine (Mox). The Nle-rhPrPC variant is an α-helix rich protein (like Met-rhPrPC) resistant to oxidation that lacks the in vitro aggregation properties of the parent protein. Conversely, the Mox-rhPrPC variant is a β-sheet rich protein that features strong proaggregation behavior. In contrast to the parent Met-rhPrPC, the Nle/Mox-containing variants are not sensitive to periodate-induced in vitro aggregation. The experimental results fully support a direct correlation of the α→β secondary structure conversion in rhPrPC with the conformational preferences of Met/Nle/Mox residues. Accordingly, sporadic prion and other neurodegenerative diseases, as well as various aging processes, might also be caused by oxidative stress leading to Met oxidation. PMID:19416900

Overview of the PCDD/Fs degradation potential and formation risk in the application of advanced oxidation processes (AOPs) to wastewater treatment.

PubMed

Vallejo, Marta; Fresnedo San Román, M; Ortiz, Inmaculada; Irabien, Angel

2015-01-01

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are a family of unintentionally produced persistent organic pollutants (POPs) that have received considerable public and scientific attention due to the toxicity of some of their congeners, more specifically those with chlorine substitution in the 2,3,7,8 positions. The environmental management and control of PCDD/Fs is addressed at a global level through the Stockholm Convention that establishes that POPs should be destroyed or irreversibly transformed in order to reduce or eliminate their release to the environment. Several technologies, including advanced oxidation processes (AOPs) such as photolysis, photocatalysis and Fenton oxidation, have been considered as effective methods for destroying PCDD/Fs in polluted waters. Nevertheless, during the remediation of wastewaters it is critical that the treatment technologies applied do not lead to the formation of by-products that are themselves POPs, especially if PCDD/Fs precursors or chlorine are present in the reaction medium. Despite the high effectiveness of AOPs in the oxidation of major contaminants, scarce references deal with the monitoring of PCDD/Fs in the course of the oxidation process, revealing that a detailed assessment of non-combustion technologies with respect to PCDD/Fs formation is still lacking. This study reports a review of the state of the art related to the potential remediation and/or formation of PCDD/Fs as a result of the application of AOPs for the treatment of polluted waters, warning on the correct selection of the operating conditions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Application of electrochemical technology for removing petroleum hydrocarbons from produced water using lead dioxide and boron-doped diamond electrodes.

PubMed

Gargouri, Boutheina; Gargouri, Olfa Dridi; Gargouri, Bochra; Trabelsi, Souhel Kallel; Abdelhedi, Ridha; Bouaziz, Mohamed

2014-12-01

Although diverse methods exist for treating polluted water, the most promising and innovating technology is the electrochemical remediation process. This paper presents the anodic oxidation of real produced water (PW), generated by the petroleum exploration of the Petrobras plant-Tunisia. Experiments were conducted at different current densities (30, 50 and 100 mA cm(-2)) using the lead dioxide supported on tantalum (Ta/PbO2) and boron-doped diamond (BDD) anodes in an electrolytic batch cell. The electrolytic process was monitored by the chemical oxygen demand (COD) and the residual total petroleum hydrocarbon [TPH] in order to know the feasibility of electrochemical treatment. The characterization and quantification of petroleum wastewater components were performed by gas chromatography mass spectrometry. The COD removal was approximately 85% and 96% using PbO2 and BDD reached after 11 and 7h, respectively. Compared with PbO2, the BDD anode showed a better performance to remove petroleum hydrocarbons compounds from produced water. It provided a higher oxidation rate and it consumed lower energy. However, the energy consumption and process time make useless anodic oxidation for the complete elimination of pollutants from PW. Cytotoxicity has shown that electrochemical oxidation using BDD could be efficiently used to reduce more than 90% of hydrocarbons compounds. All results suggest that electrochemical oxidation could be an effective approach to treat highly concentrated organic pollutants present in the industrial petrochemical wastewater and significantly reduce the cost and time of treatment. Copyright © 2014 Elsevier Ltd. All rights reserved.

Synthesis of polyrotaxanes from acetyl-β-cyclodextrin

NASA Astrophysics Data System (ADS)

Ristić, I. S.; Nikolić, L.; Nikolić, V.; Ilić, D.; Budinski-Simendić, J.

2011-12-01

Polyrotaxanes are intermediary products in the synthesis of topological gels. They are created by inclusion complex formation of hydrophobic linear macromolecules with cyclodextrins or their derivatives. Then, pairs of cyclodextrin molecules with covalently linkage were practically forming the nodes of the semi-flexible polymer network. Such gels are called topological gels and they can absorb huge quantities of water due to the net flexibility allowing the poly(ethylene oxide) chains to slide through the cyclodextrin cavities, without being pulled out altogether. For polyrotaxane formation poly(ethylene oxide) was used like linear macromolecules. There are hydroxyl groups at poly(ethylene oxide) chains, whereby the linking of the voluminous molecules should be made. To avoid the reaction of cyclodextrin OH groups with stoppers, they should be protected by, e.g., acetylation. In this work, the acetylation of the OH groups of β-cyclodextrin was performed by acetic acid anhydride with iodine as the catalyst. The acetylation reaction was assessed by the FTIR and HPLC method. By the HPLC analysis was found that the acetylation was completed in 20 minutes. Inserting of poly(ethylene oxide) with 4000 g/mol molecule mass into acetyl-β-cyclodextrin with 2:1 poly(ethylene oxide) monomer unit to acetyl-β-cyclodextrin ratio was also monitored by FTIR, and it was found that the process was completed in 12 h at the temperature of 10°C. If the process is performed at temperatures above 10°C, or for periods longer than 12 hours, the process of uncontrolled hydrolysis of acetate groups was initiated.

Evaluating the potential for quantitative monitoring of in situ chemical oxidation of aqueous-phase TCE using in-phase and quadrature electrical conductivity

NASA Astrophysics Data System (ADS)

Hort, R. D.; Revil, A.; Munakata-Marr, J.; Mao, D.

2015-07-01

Electrical resistivity measurements can potentially be used to remotely monitor fate and transport of ionic oxidants such as permanganate (MnO4-) during in situ chemical oxidation (ISCO) of contaminants like trichloroethene (TCE). Time-lapse two-dimensional bulk conductivity and induced polarization surveys conducted during a sand tank ISCO simulation demonstrated that MnO4- plume movement could be monitored in a qualitative manner using bulk conductivity tomograms, although chargeability was below sensitivity limits. We also examined changes to in-phase and quadrature electrical conductivity resulting from ion injection, MnO2 and Cl- production, and pH change during TCE and humate oxidation by MnO4- in homogeneous aqueous solutions and saturated porous media samples. Data from the homogeneous samples demonstrated that inversion of the sand tank resistivity data using a common Tikhonov regularization approach was insufficient to recover an accurate conductivity distribution within the tank. While changes to in-phase conductivity could be successfully modeled, quadrature conductivity values could not be directly related to TCE oxidation product or MnO4- concentrations at frequencies consistent with field induced polarization surveys, limiting the utility of quadrature conductivity for monitoring ISCO.

NOX/NOY MONITORING USING MODIFIED/UNMODIFIED COMMERCIAL INSTRUMENTATION

EPA Science Inventory

Three systems were used for monitoring oxides of nitrogen (NO, NO2, Noy, at the Cornelia Fort Airpark site in the 1999 Southern Oxidant Study near Nashville, TN during the months of June and July. Of the three systems, one was an unmodified ultraviolet differential optical abs...

Investigating the performance of three modified activated sludge processes treating municipal wastewater in organic pollutants removal and toxicity reduction.

PubMed

Han, Xue; Zuo, Yu-Ting; Hu, Yu; Zhang, Jie; Zhou, Meng-Xuan; Chen, Mo; Tang, Fei; Lu, Wen-Qing; Liu, Ai-Lin

2018-02-01

This study investigated the treatment performance of three types of modified activated sludge processes, i.e., anoxic/oxic (A/O), anaerobic/anoxic/oxic (A2/O) and oxidation ditch process, in treating municipal wastewater by measuring physicochemical and spectroscopic parameters, and the toxicity of the influents and effluents collected from 8 full-scale municipal wastewater treatment plants (MWTPs). The relationships between spectroscopic and physicochemical parameters of the wastewater samples and the applicability of the nematode Caenorhabditis elegans (C. elegans) bioassays for the assessment of the toxic properties of municipal wastewater were also evaluated. The results indicated that the investigated MWTPs employing any of A/O, A2/O and oxidation ditch processes could effectively control the discharge of major wastewater pollutants including biochemical oxygen demand (BOD), chemical oxygen demand, nitrogen and phosphorus. The oxidation ditch process appeared to have the advantage of removing tyrosine-like substances and presented slightly better removal efficiency of tryptophan-like fluorescent (peak T) substances than the A/O and A2/O processes. Both ultraviolet absorbance at 254nm and peak T may be used to characterize the organic load of municipal wastewater, and peak T can be adopted as a gauge of the BOD removal efficacy of municipal wastewater treatment. Using C. elegans-based oxygen consumption rate assay for monitoring municipal wastewater toxicity deserves further investigations. Copyright © 2017 Elsevier Inc. All rights reserved.

Electrochemical Detection of Multiple Bioprocess Analytes

NASA Technical Reports Server (NTRS)

Rauh, R. David

2010-01-01

An apparatus that includes highly miniaturized thin-film electrochemical sensor array has been demonstrated as a prototype of instruments for simultaneous detection of multiple substances of interest (analytes) and measurement of acidity or alkalinity in bioprocess streams. Measurements of pH and of concentrations of nutrients and wastes in cell-culture media, made by use of these instruments, are to be used as feedback for optimizing the growth of cells or the production of desired substances by the cultured cells. The apparatus is designed to utilize samples of minimal volume so as to minimize any perturbation of monitored processes. The apparatus can function in a potentiometric mode (for measuring pH), an amperometric mode (detecting analytes via oxidation/reduction reactions), or both. The sensor array is planar and includes multiple thin-film microelectrodes covered with hydrous iridium oxide. The oxide layer on each electrode serves as both a protective and electrochemical transducing layer. In its transducing role, the oxide provides electrical conductivity for amperometric measurement or pH response for potentiometric measurement. The oxide on an electrode can also serve as a matrix for one or more enzymes that render the electrode sensitive to a specific analyte. In addition to transducing electrodes, the array includes electrodes for potential control. The array can be fabricated by techniques familiar to the microelectronics industry. The sensor array is housed in a thin-film liquid-flow cell that has a total volume of about 100 mL. The flow cell is connected to a computer-controlled subsystem that periodically draws samples from the bioprocess stream to be monitored. Before entering the cell, each 100-mL sample is subjected to tangential-flow filtration to remove particles. In the present version of the apparatus, the electrodes are operated under control by a potentiostat and are used to simultaneously measure the pH and the concentration of glucose. It is anticipated that development of procedures for trapping more enzymes into hydrous iridium oxide (and possibly into other electroactive metal oxides) and of means for imparting long-term stability to the transducer layers should make it possible to monitor concentrations of products of many enzyme reactions for example, such key bioprocess analytes as amino acids, vitamins, lactose, and acetate.

Monitoring Tensile Fatigue of Superelastic NiTi Wire in Liquids by Electrochemical Potential

NASA Astrophysics Data System (ADS)

Racek, Jan; Stora, Marc; Šittner, Petr; Heller, Luděk; Kopeček, Jaromir; Petrenec, Martin

2015-06-01

Fatigue of superelastic NiTi wires was investigated by cyclic tension in simulated biofluid. The state of the surface of the fatigued NiTi wire was monitored by following the evolution of the electrochemical open circuit potential (OCP) together with macroscopic stresses and strains. The ceramic TiO2 oxide layer on the NiTi wire surface cannot withstand the large transformation strain and fractures in the first cycle. Based on the analysis of the results of in situ OCP experiments and SEM observation of cracks, it is claimed that the cycled wire surface develops mechanochemical reactions at the NiTi/liquid interface leading to cumulative generation of hydrogen, uptake of the hydrogen by the NiTi matrix, local loss of the matrix strength, crack transfer into the NiTi matrix, accelerated crack growth, and ultimately to the brittle fracture of the wire. Fatigue degradation is thus claimed to originate from the mechanochemical processes occurring at the excessively deforming surface not from the accumulation of defects due to energy dissipative bulk deformation processes. Ironically, combination of the two exciting properties of NiTi—superelasticity due to martensitic transformation and biocompatibility due to the protective TiO2 surface oxide layer—leads to excessive fatigue damage during cyclic mechanical loading in biofluids.

Removal of macro-pollutants in oily wastewater obtained from soil remediation plant using electro-oxidation process.

PubMed

Zolfaghari, Mehdi; Drogui, Patrick; Blais, Jean François

2018-03-01

Electro-oxidation process by niobium boron-doped diamond (Nb/BDD) electrode was used to treat non-biodegradable oily wastewater provided from soil leachate contaminated by hydrocarbons. Firstly, the diffusion current limit and mass transfer coefficient was experimentally measured (7.1 mA cm -2 and 14.7 μm s -1 , respectively), in order to understand minimum applied current density. Later on, the oxidation kinetic model of each pollutant was investigated in different current densities ranged between 3.8 and 61.5 mA cm -2 . It was observed that direct oxidation was the main removal mechanism of organic and inorganic carbon, while the indirect oxidation in higher current density was responsible for nitrogen oxidation. Hydrocarbon in the form of colloidal particles could be removed by electro-flotation. On the other hand, electro-decomposition on the surface of cathode and precipitation by hydroxyl ions were the utmost removal pathway of metals. According to the initial experiments, operating condition was further optimized by central composite design model in different current density, treatment time, and electrolyte addition, based on the best responses on the specific energy consumption (SEC), chemical oxygen demand (COD), and total organic carbon (TOC) removal efficiency. Unde r optimum operating condition (current density = 23.1 mA cm -2 , time = 120 min, Ti/Pt as a cathode, and Nb/BDD as the anode), electro-oxidation showed the following removal efficiencies: COD (84.6%), TOC (68.2%), oil and grease (99%), color (87.9%), total alkalinity (92%), N tot (18%), NH 4 + (31%), Ca (66.4%), Fe (71.1%), Mg (41.4%), Mn (78.1%), P tot (75%), S (67.1%), and Si (19.1%). Graphical abstract Environmental significance statement Soil treatment facilities are rapidly grown throughout the world, especially in North America due to its intense industrialization. High water content soil in humid area like Canada produces significant amount of leachate which is difficult to remove by physical and biological processes. Current treatment facility was modified by applying the electro-chemical oxidation process. The kinetic models of each macro-pollutant included carbon, nitrogen, phosphorous, and metals were developed to investigate their oxidation mechanism (graphical abstract). The efficiency of treatment was monitored in order to optimize the decisive operating parameters of electro-oxidation process. The result of this article could pave the way of future investigation on efficient treatment of variety of oily wastewater.

Advanced oxidation processes on doxycycline degradation: monitoring of antimicrobial activity and toxicity.

PubMed

Spina-Cruz, Mylena; Maniero, Milena Guedes; Guimarães, José Roberto

2018-05-08

Advanced oxidation processes (AOPs) have been highly efficient in degrading contaminants of emerging concern (CEC). This study investigated the efficiency of photolysis, peroxidation, photoperoxidation, and ozonation at different pH values to degrade doxycycline (DC) in three aqueous matrices: fountain, tap, and ultrapure water. More than 99.6% of DC degradation resulted from the UV/H 2 O 2 and ozonation processes. Also, to evaluate the toxicity of the original solution and throughout the degradation time, antimicrobial activity tests were conducted using Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacteria, and acute toxicity test using the bioluminescent marine bacterium (Vibrio fischeri). Antimicrobial activity reduced as the drug degradation increased in UV/H 2 O 2 and ozonation processes, wherein the first process only 6 min was required to reduce 100% of both bacteria activity. In ozonation, 27.7 mg L -1 of ozone was responsible for reducing 100% of the antimicrobial activity. When applied the photoperoxidation process, an increase in the toxicity occurred as the high levels of degradation were achieved; it means that toxic intermediates were formed. The ozonated solutions did not present toxicity.

In Vitro Monitoring of the Mitochondrial Beta-Oxidation Flux of Palmitic Acid and Investigation of Its Pharmacological Alteration by Therapeutics.

PubMed

Murgasova, Renata; Tor Carreras, Ester; Bourgailh, Julien

2018-05-03

The present study was designed to validate the functional assay that enables rapid screening of therapeutic candidates for their effect on mitochondrial fatty acid oxidation. The two whole-cell systems (tissue homogenates and hepatocytes) have been evaluated to monitor the total beta-oxidation flux of physiologically important 3 H-palmitic acid by measurement of tritiated water enrichment in incubations using UPLC coupled on-line to radioactivity monitoring and mass spectrometry. Our results with several known inhibitors of fatty acid oxidation showed that this simple assay could correctly predict a potential in alteration of mitochondrial function by drug candidates. Since the beta-oxidation of palmitic acid takes place almost exclusively in mitochondria of human hepatocytes, this model can be also utilized to distinguish between the mitochondrial and peroxisomal routes of this essential metabolic pathway in some cases. The present work offers a new in vitro screen of changes in mitochondrial beta-oxidation by xenobiotics as well as a model to study the mechanism of this pathway.

Modified WO3 nanorod with Pt nanoparticle as retrievable materials in catalytic and photocatalytic aerobic oxidation of alcohols

NASA Astrophysics Data System (ADS)

Hosseini, Farnaz; Safaei, Elham; Mohebbi, Sajjad

2017-07-01

This study has focused on catalytic and photocatalytic oxidation of aromatic alcohols using WO3 nanorod and a series of Pt/WO3 nanocomposite Pt nanoparticles was loaded on WO3 nanorod with several mass ratios 0.1, 0.2, and 0.3 via a photoreduction process (PRP) and characterized by TEM, FE-SEM imaging, EDAX, XRD, DRS, ICP, and XPS. WO3 nanorods were obtained monodispersed with average 40-nm diameter and square cross section without significant size change by the loading of platinum nanoparticles on it. Progress of oxidation reaction was monitored by GC and the yield of aerobic photocatalytic oxidation of alcohols reached up to 98% for Pt/WO3 and 69% for WO3 while, no oxidation was detected in the absence of light. The highest photocatalytic performance was obtained for mass ratio 0.2 with the selectivity >99%. So, this nanocomposite has potentials to be used as high-performance heterogeneous catalyst and photocatalyst under visible light irradiation with advantages of high activity, high selectivity, and reusability.

Si Oxidation and H 2 Gassing During Aqueous Slurry Preparation for Li-Ion Battery Anodes

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

Hays, Kevin A.; Key, Baris; Li, Jianlin

Si has the possibility to greatly increase the energy density of Li-ion battery anodes, though it is not without its problems. One issue often overlooked is the decomposition of Si during large scale slurry formulation and battery fabrication. Here, we investigate the mechanism of H 2 production to understand the role of different slurry components and their impact on the Si oxidation and surface chemistry. Mass spectrometry and in situ pressure monitoring identifies that carbon black plays a major role in promoting the oxidation of Si and generation of H 2. Si oxidation also occurs through atmospheric O 2 consumption.more » Both pathways, along with solvent choice, impact the surface silanol chemistry, as analyzed by 1H– 29Si cross-polarization magic angle spinning nuclear magnetic resonance (MAS NMR) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR FTIR). An understanding of the oxidation of Si, during slurry processing, provides a pathway toward improving the manufacturing of Si based anodes by maximizing its capacity and minimizing safety hazards.« less

Stability study: Transparent conducting oxides in chemically reactive plasmas

NASA Astrophysics Data System (ADS)

Manjunatha, Krishna Nama; Paul, Shashi

2017-12-01

Effect of plasma treatment on transparent conductive oxides (TCOs) including indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO) and aluminium-doped zinc oxide (AZO) are discussed. Stability of electrical and optical properties of TCOs, when exposed to plasma species generated from gases such as hydrogen and silane, are studied extensively. ITO and FTO thin films are unstable and reduce to their counterparts such as Indium and Tin when subjected to plasma. On the other hand, AZO is not only stable but also shows superior electrical and optical properties. The stability of AZO makes it suitable for electronic applications, such as solar cells and transistors that are fabricated under plasma environment. TCOs exposed to plasma with different fabrication parameters are used in the fabrication of silicon nanowire solar cells. The performance of solar cells, which is mired by the plasma, fabricated on ITO and FTO is discussed with respect to plasma exposure parameters while showing the advantages of using chemically stable AZO as an ideal TCO for solar cells. Additionally, in-situ diagnostic tool (optical emission spectroscopy) is used to monitor the deposition process and damage caused to TCOs.

Si Oxidation and H 2 Gassing During Aqueous Slurry Preparation for Li-Ion Battery Anodes

DOE PAGES

Hays, Kevin A.; Key, Baris; Li, Jianlin; ...

2018-04-24

Si has the possibility to greatly increase the energy density of Li-ion battery anodes, though it is not without its problems. One issue often overlooked is the decomposition of Si during large scale slurry formulation and battery fabrication. Here, we investigate the mechanism of H 2 production to understand the role of different slurry components and their impact on the Si oxidation and surface chemistry. Mass spectrometry and in situ pressure monitoring identifies that carbon black plays a major role in promoting the oxidation of Si and generation of H 2. Si oxidation also occurs through atmospheric O 2 consumption.more » Both pathways, along with solvent choice, impact the surface silanol chemistry, as analyzed by 1H– 29Si cross-polarization magic angle spinning nuclear magnetic resonance (MAS NMR) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR FTIR). An understanding of the oxidation of Si, during slurry processing, provides a pathway toward improving the manufacturing of Si based anodes by maximizing its capacity and minimizing safety hazards.« less

Time-course proteomics dataset to monitor protein-bound methionine oxidation in Bacillus cereus ATCC 14579.

PubMed

Madeira, Jean-Paul; Alpha-Bazin, Béatrice; Armengaud, Jean; Duport, Catherine

2018-06-01

Aerobic respiratory growth generates endogenous reactive oxygen species (ROS). ROS oxidize protein-bound methionine residues into methionine sulfoxide. Methionine sulfoxide reductases catalyze the reduction of methionine sulfoxide to methionine in proteins. Here, we use high-throughput nanoLC-MS/MS methodology to establish detailed maps of oxidized proteins from Bacillus cereus ATCC 14579 ΔpBClin15 and its mutant for which the methionine sulfoxide reductase AB gene ( msrAB ) has been inactivated (Madeira et al., 2017) [1]. Lists of oxidized peptides and proteins identified at early exponential, late exponential and stationary growth phases are supplied in this article as data files. Raw data are deposited at the ProteomeXchange Consortium via the PRIDE partner repository with the dataset identifiers, PXD006169 and PDX006205 (http://www.ebi.ac/uk). Given the importance of methionine oxidation in several key cellular processes and its impact in the field of medical and food microbiology, this paper should be useful for further insightful redox studies in B. cereus and its numerous relatives.

Real-Time Observation of Atomic Layer Deposition Inhibition: Metal Oxide Growth on Self-Assembled Alkanethiols

DOE PAGES

Avila, Jason R.; DeMarco, Erica J.; Emery, Jonathan D.; ...

2014-07-21

Through in-situ quartz crystal microbalance (QCM) monitoring we resolve the growth of a self-assembled monolayer (SAM) and subsequent metal oxide deposition with high resolution. Here, we introduce the fitting of mass deposited during each atomic layer deposition (ALD) cycle to an analytical island-growth model that enables quantification of growth inhibition, nucleation density, and the uninhibited ALD growth rate. A long-chain alkanethiol was self-assembled as a monolayer on gold-coated quartz crystals in order to investigate its effectiveness as a barrier to ALD. Compared to solution-loading, vapor-loading is observed to produce a SAM with equal or greater inhibition-ability in minutes vs. days.more » The metal oxide growth temperature and the choice of precursor also significantly affect the nucleation density, which ranges from 0.001 to 1 sites/nm 2. Finally, we observe a minimum 100 cycle inhibition of an oxide ALD process, ZnO, under moderately optimized conditions.« less

A CMOS-Compatible Poly-Si Nanowire Device with Hybrid Sensor/Memory Characteristics for System-on-Chip Applications

PubMed Central

Chen, Min-Cheng; Chen, Hao-Yu; Lin, Chia-Yi; Chien, Chao-Hsin; Hsieh, Tsung-Fan; Horng, Jim-Tong; Qiu, Jian-Tai; Huang, Chien-Chao; Ho, Chia-Hua; Yang, Fu-Liang

2012-01-01

This paper reports a versatile nano-sensor technology using “top-down” poly-silicon nanowire field-effect transistors (FETs) in the conventional Complementary Metal-Oxide Semiconductor (CMOS)-compatible semiconductor process. The nanowire manufacturing technique reduced nanowire width scaling to 50 nm without use of extra lithography equipment, and exhibited superior device uniformity. These n type polysilicon nanowire FETs have positive pH sensitivity (100 mV/pH) and sensitive deoxyribonucleic acid (DNA) detection ability (100 pM) at normal system operation voltages. Specially designed oxide-nitride-oxide buried oxide nanowire realizes an electrically Vth-adjustable sensor to compensate device variation. These nanowire FETs also enable non-volatile memory application for a large and steady Vth adjustment window (>2 V Programming/Erasing window). The CMOS-compatible manufacturing technique of polysilicon nanowire FETs offers a possible solution for commercial System-on-Chip biosensor application, which enables portable physiology monitoring and in situ recording. PMID:22666012

Corrosion process monitoring by AFM higher harmonic imaging

NASA Astrophysics Data System (ADS)

Babicz, S.; Zieliński, A.; Smulko, J.; Darowicki, K.

2017-11-01

The atomic force microscope (AFM) was invented in 1986 as an alternative to the scanning tunnelling microscope, which cannot be used in studies of non-conductive materials. Today the AFM is a powerful, versatile and fundamental tool for visualizing and studying the morphology of material surfaces. Moreover, additional information for some materials can be recovered by analysing the AFM’s higher cantilever modes when the cantilever motion is inharmonic and generates frequency components above the excitation frequency, usually close to the resonance frequency of the lowest oscillation mode. This method has been applied and developed to monitor corrosion processes. The higher-harmonic imaging is especially helpful for sharpening boundaries between objects in heterogeneous samples, which can be used to identify variations in steel structures (e.g. corrosion products, steel heterogeneity). The corrosion products have different chemical structures because they are composed of chemicals other than the original metal base (mainly iron oxides). Thus, their physicochemical properties are different from the primary basis. These structures have edges at which higher harmonics should be more intense because of stronger interference between the tip and the specimen structure there. This means that the AFM’s higher-harmonic imaging is an excellent tool for monitoring surficial effects of the corrosion process.

Original Experimental Approach for Assessing Transport Fuel Stability.

PubMed

Bacha, Kenza; Ben Amara, Arij; Alves Fortunato, Maira; Wund, Perrine; Veyrat, Benjamin; Hayrault, Pascal; Vannier, Axel; Nardin, Michel; Starck, Laurie

2016-10-21

The study of fuel oxidation stability is an important issue for the development of future fuels. Diesel and kerosene fuel systems have undergone several technological changes to fulfill environmental and economic requirements. These developments have resulted in increasingly severe operating conditions whose suitability for conventional and alternative fuels needs to be addressed. For example, fatty acid methyl esters (FAMEs) introduced as biodiesel are more prone to oxidation and may lead to deposit formation. Although several methods exist to evaluate fuel stability (induction period, peroxides, acids, and insolubles), no technique allows one to monitor the real-time oxidation mechanism and to measure the formation of oxidation intermediates that may lead to deposit formation. In this article, we developed an advanced oxidation procedure (AOP) based on two existing reactors. This procedure allows the simulation of different oxidation conditions and the monitoring of the oxidation progress by the means of macroscopic parameters, such as total acid number (TAN) and advanced analytical methods like gas chromatography coupled to mass spectrometry (GC-MS) and Fourier Transform Infrared - Attenuated Total Reflection (FTIR-ATR). We successfully applied AOP to gain an in-depth understanding of the oxidation kinetics of a model molecule (methyl oleate) and commercial diesel and biodiesel fuels. These developments represent a key strategy for fuel quality monitoring during logistics and on-board utilization.

Realizing Full Coverage of Stable Perovskite Film by Modified Anti-Solvent Process

NASA Astrophysics Data System (ADS)

Ji, Long; Zhang, Ting; Wang, Yafei; Zhang, Peng; Liu, Detao; Chen, Zhi; Li, Shibin

2017-05-01

Lead-free solution-processed solid-state photovoltaic devices based on formamidinium tin triiodide (FASnI3) and cesium tin triiodide (CsSnI3) perovskite semiconductor as the light harvester are reported. In this letter, we used solvent engineering and anti-solvent dripping method to fabricate perovskite films. SnCl2 was used as an inhibitor of Sn4+ in FASnI3 precursor solution. We obtained the best films under the function of toluene or chlorobenzene in anti-solvent dripping method and monitored the oxidation of FASnI3 films in air. We chose SnF2 as an additive of CsSnI3 precursor solution to prevent the oxidation of the Sn2+, improving the stability of CsSnI3. The experimental results we obtained can pave the way for lead-free tin-based perovskite solar cells (PSCs).

Dip-coating of nano-sized CeO2 on SiC membrane and its effect on thermal diffusivity.

PubMed

Park, Jihye; Jung, Miewon

2014-05-01

CeO2-SiC mixed composite membrane was fabricated with porous SiC ceramic and cerium oxide powder synthesized by sol-gel process. This CeO2-SiC membrane and SiC membrane which is made by the purified SiC ceramic were pressed and sintered in Ar atmosphere. And then, the SiC membrane was dip-coated by cerium oxide precursor sol solution and heat-treated in air. The surface morphology, particle size, porosity and structure analysis of the mixing and dip-coating SiC membrane were monitored by FE-SEM and X-ray diffraction analysis. Surface area, pore volume and pore diameter were determined by BET instrument. Thermal diffusivity was measured by laser flash method with increasing temperature. The relation between porosity and thermal diffusivity from different preparation process has been discussed on this study.

Laccase from Pycnoporus cinnabarinus and phenolic compounds: can the efficiency of an enzyme mediator for delignifying kenaf pulp be predicted?

PubMed

Andreu, Glòria; Vidal, Teresa

2013-03-01

In this work, kenaf pulp was delignified by using laccase in combination with various redox mediators and the efficiency of the different laccase–mediator systems assessed in terms of the changes in pulp properties after bleaching. The oxidative ability of the individual mediators used (acetosyringone, syringaldehyde, p-coumaric acid, vanillin and actovanillone) and the laccase–mediator systems was determined by monitoring the oxidation–reduction potential (ORP) during process. The results confirmed the production of phenoxy radicals of variable reactivity and stressed the significant role of lignin structure in the enzymatic process. Although changes in ORP were correlated with the oxidative ability of the mediators, pulp properties as determined after the bleaching stage were also influenced by condensation and grafting reactions. As shown here, ORP measurements provide a first estimation of the delignification efficiency of a laccase–mediator system. Copyright © 2013 Elsevier Ltd. All rights reserved.

Olive oil quality and ripening in super-high-density Arbequina orchard.

PubMed

Benito, Marta; Lasa, José Manuel; Gracia, Pilar; Oria, Rosa; Abenoza, María; Varona, Luis; Sánchez-Gimeno, Ana Cristina

2013-07-01

The aim of this work was to evaluate the evolution of the quality of extra virgin olive oil obtained from a super-high-density Arbequina orchard, under a drip irrigation system, throughout the ripening process. For this objective, physicochemical, nutritional and sensory parameters were studied. In addition, the oxidative stability, pigment content and colour evolution of olive oil were analysed during the ripening process. Free acidity increased slightly throughout the ripening process, while peroxide value and extinction coefficient decreased. Total phenol content and oxidative stability showed a similar trend, increasing at the beginning of ripening up to a maximum and thereafter decreasing. α-Tocopherol and pigment contents decreased with ripening, leading to changes in colour coordinates. Sensory parameters were correlated with total phenol content, following a similar trend throughout the maturation process. By sampling and monitoring the ripeness index weekly, it would be possible to determine an optimal harvesting time for olives according to the industrial yield and the physicochemical, nutritional and sensory properties of the olive oil. © 2012 Society of Chemical Industry.

Solid fat content measurement as a substitute for total polar compound analysis

USDA-ARS?s Scientific Manuscript database

Monitoring of oxidative degradation in frying oils is essential for determining an appropriate discard time. The most reliable method for monitoring the extent of oxidation in edible oils is the determination of total polar compounds. However, this method is time-consuming and not practical to execu...

Solid fat content measurement as an alternative to total polar compound analysis

USDA-ARS?s Scientific Manuscript database

Monitoring of oxidative degradation in frying oils is essential for determining an appropriate discard time. The most reliable method for monitoring the extent of oxidation in edible oils is the determination of total polar compounds (TPC). However, this method is time-consuming and not practical ...

Monitoring the layer-by-layer self-assembly of graphene and graphene oxide by spectroscopic ellipsometry.

PubMed

Zhou, Kai-Ge; Chang, Meng-Jie; Wang, Hang-Xing; Xie, Yu-Long; Zhang, Hao-Li

2012-01-01

Thin films of graphene oxide, graphene and copper (II) phthalocyanine dye have been successfully fabricated by electrostatic layer-by-layer (LbL) assembly approach. We present the first variable angle spectroscopic ellipsometry (VASE) investigation on these graphene-dye hybrid thin films. The thickness evaluation suggested that our LbL assembly process produces highly uniform and reproducible thin films. We demonstrate that the refractive indices of the graphene-dye thin films undergo dramatic variation in the range close to the absorption of the dyes. This investigation provides new insight to the optical properties of graphene containing thin films and shall help to establish an appropriate optical model for graphene-based hybrid materials.

Improvement of charge-pumping electrically detected magnetic resonance and its application to silicon metal-oxide-semiconductor field-effect transistor

NASA Astrophysics Data System (ADS)

Hori, Masahiro; Tsuchiya, Toshiaki; Ono, Yukinori

2017-01-01

Charge-pumping electrically detected magnetic resonance (CP EDMR), or EDMR in the CP mode, is improved and applied to a silicon metal-oxide-semiconductor field-effect transistor (MOSFET). Real-time monitoring of the CP process reveals that high-frequency transient currents are an obstacle to signal amplification for EDMR. Therefore, we introduce cutoff circuitry, leading to a detection limit for the number of spins as low as 103 for Si MOS interface defects. With this improved method, we demonstrate that CP EDMR inherits one of the most important features of the CP method: the gate control of the energy window of the detectable interface defects for spectroscopy.

Structural Characterization of Oxidized Glycerophosphatidylserine: Evidence of Polar Head Oxidation

NASA Astrophysics Data System (ADS)

Maciel, Elisabete; da Silva, Raquel Nunes; Simões, Cláudia; Domingues, Pedro; Domingues, M. Rosário M.

2011-10-01

Non-oxidized phosphatidylserine (PS) is known to play a key role in apoptosis but there is considerable research evidence suggesting that oxidized PS also plays a role in this event, leading to the increasing interest in studying PS oxidative modifications. In this work, different PS (1-palmitoyl-2-linoleoyl-sn-glycero-3-phospho-L-serine (PLPS), 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine (POPS), and 1,2-dipalmitoyl-sn-glycero-3-phospho-L-serine (DPPS) were oxidized in vitro by hydroxyl radical, generated under Fenton reaction conditions, and the reactions were monitored by ESI-MS in negative mode. Oxidation products were then fractionated by thin layer chromatography (TLC) and characterized by tandem mass spectrometry (MS/MS). This approach allowed the identification of hydroxyl, peroxy, and keto derivatives due to oxidation of unsaturated fatty acyl chains. Oxidation products due to oxidation of serine polar head were also identified. These products, with lower molecular weight than the non-modified PS, were identified as [M - 29 - H]- (terminal acetic acid), [M - 30 - H]- (terminal acetamide), [M - 13 - H]- (terminal hydroperoxyacetaldehyde), and [M - 13 - H]- (terminal hydroxyacetaldehyde plus hydroxy fatty acyl chain). Phosphatidic acid was also formed in these conditions. These findings confirm the oxidation of the serine polar head induced by the hydroxyl radical. The identification of these modifications may be a valuable tool to evaluate phosphatidylserine alteration under physiopathologic conditions and also to help understand the biological role of phosphatidylserine oxidation in the apoptotic process and other biological functions.

An electrochemical sensor based on polyaniline for monitoring hydroquinone and its damage on DNA.

PubMed

Tang, Wenwei; Zhang, Min; Li, Weihao; Zeng, Xinping

2014-09-01

A dsDNA/PANI/CTS/GCE biosensor was constructed by using the biocompatible chitosan (CTS) and the polyaniline (PANI) with excellent electric catalytic properties and large specific surface areas. The electrochemical behavior of hydroquinone on biosensor and its DNA-damaging mechanisms were investigated. Results showed that the redox peak current was remarkably increased after glassy carbon electrode (GCE) was modified by PANI/CTS. The dsDNA damage by hydroquinone was concentration dependent, and increased along with the increase of hydroquinone oxidation peak current and the reduction of dsDNA guanine oxidation peak current. The linear detection range of hydroquinone with dsDNA/PANI/CTS/GCE was 1.25×10(-6)-3.2×10(-4) M, and the detection limit was 9.65×10(-7) M. It was confirmed by the UV method that applying dsDNA/PANI/CTS/GCE to monitor hydroquinone was accurate and reliable. In addition, it could be deduced that the mode of interaction between the hydroquinone and dsDNA was intercalation. The electrochemical oxidation of hydroquinone on the dsDNA/PANI/CTS/GCE electrode was an adsorption-controlled irreversible and a two-electron two-proton transfer process. Copyright © 2014 Elsevier B.V. All rights reserved.

Proteomic detection of oxidized and reduced thiol proteins in cultured cells.

PubMed

Cuddihy, Sarah L; Baty, James W; Brown, Kristin K; Winterbourn, Christine C; Hampton, Mark B

2009-01-01

The oxidation and reduction of cysteine residues is emerging as an important post-translational control of protein function. We describe a method for fluorescent labelling of either reduced or oxidized thiols in combination with two-dimensional sodium dodecyl sulphate polyacrylamide gel electrophoresis (2DE) to detect changes in the redox proteome of cultured cells. Reduced thiols are labelled with the fluorescent compound 5-iodoacetamidofluorescein. To monitor oxidized thiols, the reduced thiols are first blocked with N-ethyl-maleimide, then the oxidized thiols reduced with dithiothreitol and labelled with 5-iodoacetamidofluorescein. The method is illustrated by treating Jurkat T-lymphoma cells with hydrogen peroxide and monitoring increased labelling of oxidized thiol proteins. A decrease in labelling can also be detected, and this is attributed to the formation of higher oxidation states of cysteine that are not reduced by dithiothreitol.

Solar Fenton and solar TiO2 catalytic treatment of ofloxacin in secondary treated effluents: evaluation of operational and kinetic parameters.

PubMed

Michael, I; Hapeshi, E; Michael, C; Fatta-Kassinos, D

2010-10-01

Two different technical approaches based on advanced oxidation processes (AOPs), solar Fenton homogeneous photocatalysis (hv/Fe(2+)/H(2)O(2)) and heterogeneous photocatalysis with titanium dioxide (TiO(2)) suspensions were studied for the chemical degradation of the fluoroquinolone ofloxacin in secondary treated effluents. A bench-scale solar simulator in combination with an appropriate photochemical batch reactor was used to evaluate and select the optimal oxidation conditions of ofloxacin spiked in secondary treated domestic effluents. The concentration profile of the examined substrate during degradation was determined by UV/Vis spectrophotometry. Mineralization was monitored by measuring the dissolved organic carbon (DOC). The concentrations of Fe(2+) and H(2)O(2) were the key factors for the solar Fenton process, while the most important parameter of the heterogeneous photocatalysis was proved to be the catalyst loading. Kinetic analyses indicated that the photodegradation of ofloxacin can be described by a pseudo-first-order reaction. The rate constant (k) for the solar Fenton process was determined at different Fe(2+) and H(2)O(2) concentrations whereas the Langmuir-Hinshelwood (LH) kinetic expression was used to assess the kinetics of the heterogeneous photocatalytic process. The conversion of ofloxacin depends on several parameters based on the various experimental conditions, which were investigated. A Daphnia magna bioassay was used to evaluate the potential toxicity of the parent compound and its photo-oxidation by-products in different stages of oxidation. In the present study solar Fenton has been demonstrated to be more effective than the solar TiO(2) process, yielding complete degradation of the examined substrate and DOC reduction of about 50% in 30 min of the photocatalytic treatment. Copyright © 2010 Elsevier Ltd. All rights reserved.

Solvent polarity effect on quality of n-octadecanethiol self-assembled monolayers on copper and oxidized copper

NASA Astrophysics Data System (ADS)

Zhang, Yaozhong; Zhou, Jun; Zhang, Xiaoli; Hu, Jun; Gao, Han

2014-11-01

This article reports the effect of solvent polarity on the formation of n-octadecanethiol self-assembled monolayers (C18SH-SAMs) on pure copper surface and oxidized copper surface. The quality of SAMs prepared in different solvents (n-hexane, toluene, trichloroethylene, chloroform, acetone, acetonitrile, ethanol) was monitored by EIS, RAIRS and XPS. The results indicated that C18SH-SAMs formed in these solvents were in good barrier properties on pure copper surface and the structures of monolayers formed in high polarity solvents were more compact and orderly than that formed in low polarity solvents. For comparison, C18SH adsorbed on the surface of oxidized copper in these solvents were studied and the results indicated that C18SH could be adsorbed on oxidized copper surface after the reduction of copper oxide layer by thiols. Compared with high polarity solvents, a limited reduction process of oxidized copper by thiols led to the incompletely formation of monolayers in low polarity solvents. This can be interpreted that the generated water on solid-liquid interface and a smaller reaction force restrict the continuous reduction reaction in low polarity solvents

Heptanuclear CoII5CoIII2 Cluster as Efficient Water Oxidation Catalyst.

PubMed

Xu, Jia-Heng; Guo, Ling-Yu; Su, Hai-Feng; Gao, Xiang; Wu, Xiao-Fan; Wang, Wen-Guang; Tung, Chen-Ho; Sun, Di

2017-02-06

Inspired by the transition-metal-oxo cubical Mn 4 CaO 5 in photosystem II, we herein report a disc-like heptanuclear mixed-valent cobalt cluster, [Co II 5 Co III 2 (mdea) 4 (N 3 ) 2 (CH 3 CN) 6 (OH) 2 (H 2 O) 2 ·4ClO 4 ] (1, H 2 mdea = N-methyldiethanolamine), for photocatalytic oxygen evolution. The topology of the Co 7 core resembles a small piece of cobaltate protected by terminal H 2 O, N 3 - , CH 3 CN, and multidentate N-methyldiethanolamine at the periphery. Under the optimal photocatalytic conditions, 1 exhibits water oxidation activity with a turnover number (TON) of 210 and a turnover frequency (TOF initial ) of 0.23 s -1 . Importantly, electrospray mass spectrometry (ESI-MS) was used to not only identify the possible main active species in the water oxidation reaction but also monitor the evolutions of oxidation states of cobalt during the photocatalytic reactions. These results shed light on the design concept of new water oxidation catalysts and mechanism-related issues such as the key active intermediate and oxidation state evolution in the oxygen evolution process. The magnetic properties of 1 were also discussed in detail.

Conductive diamond electrochemical oxidation of caffeine-intensified biologically treated urban wastewater.

PubMed

Martín de Vidales, María J; Millán, María; Sáez, Cristina; Pérez, José F; Rodrigo, Manuel A; Cañizares, Pablo

2015-10-01

In this work, the usefulness of Conductive Diamond Electrochemical Oxidation (CDEO) to degrade caffeine in real urban wastewater matrixes was assessed. The oxidation of actual wastewater intensified with caffeine (from 1 to 100 mg L(-1)) was studied, paying particular attention to the influence of the initial load of caffeine and the differences observed during the treatment of caffeine in synthetic wastewater. The results showed that CDEO is a technology that is capable of efficiently degrading this compound even at very low concentrations and that it can even be completely depleted. Profiles of the ionic species of S (SO4(2-)), N (NH4(+), NO3(-)) and Cl (ClO(-), ClO3(-) and ClO4(-)) were monitored and explained for plausible oxidation mechanisms. It was observed that the efficiency achieved is higher in the treatment of real wastewater than in the oxidation of synthetic wastewater because of the contribution of electrogenerated oxidant species such as hypochlorite. The formation of chlorate and perchlorate during electrochemical processes was observed, and a combined strategy to prevent this important drawback was successfully tested based on the application of low current densities with the simultaneous dosing of hydrogen peroxide. Copyright © 2015 Elsevier Ltd. All rights reserved.

Quantitative confirmation of diffusion-limited oxidation theories

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

Gillen, K.T.; Clough, R.L.

1990-01-01

Diffusion-limited (heterogeneous) oxidation effects are often important for studies of polymer degradation. Such effects are common in polymers subjected to ionizing radiation at relatively high dose rate. To better understand the underlying oxidation processes and to aid in the planning of accelerated aging studies, it would be desirable to be able to monitor and quantitatively understand these effects. In this paper, we briefly review a theoretical diffusion approach which derives model profiles for oxygen surrounded sheets of material by combining oxygen permeation rates with kinetically based oxygen consumption expressions. The theory leads to a simple governing expression involving the oxygenmore » consumption and permeation rates together with two model parameters {alpha} and {beta}. To test the theory, gamma-initiated oxidation of a sheet of commercially formulated EPDM rubber was performed under conditions which led to diffusion-limited oxidation. Profile shapes from the theoretical treatments are shown to accurately fit experimentally derived oxidation profiles. In addition, direct measurements on the same EPDM material of the oxygen consumption and permeation rates, together with values of {alpha} and {beta} derived from the fitting procedure, allow us to quantitatively confirm for the first time the governing theoretical relationship. 17 refs., 3 figs.« less

Probing Interfacial Processes on Graphene Surface by Mass Detection

NASA Astrophysics Data System (ADS)

Kakenov, Nurbek; Kocabas, Coskun

2013-03-01

In this work we studied the mass density of graphene, probed interfacial processes on graphene surface and examined the formation of graphene oxide by mass detection. The graphene layers were synthesized by chemical vapor deposition method on copper foils and transfer-printed on a quartz crystal microbalance (QCM). The mass density of single layer graphene was measured by investigating the mechanical resonance of the QCM. Moreover, we extended the developed technique to probe the binding dynamics of proteins on the surface of graphene, were able to obtain nonspecific binding constant of BSA protein of graphene surface in aqueous solution. The time trace of resonance signal showed that the BSA molecules rapidly saturated by filling the available binding sites on graphene surface. Furthermore, we monitored oxidation of graphene surface under oxygen plasma by tracing the changes of interfacial mass of the graphene controlled by the shifts in Raman spectra. Three regimes were observed the formation of graphene oxide which increases the interfacial mass, the release of carbon dioxide and the removal of small graphene/graphene oxide flakes. Scientific and Technological Research Council of Turkey (TUBITAK) grant no. 110T304, 109T209, Marie Curie International Reintegration Grant (IRG) grant no 256458, Turkish Academy of Science (TUBA-Gebip).

Combustion synthesis of LaFeO{sub 3} sensing nanomaterial

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

Zaza, F., E-mail: fabio.zaza@enea.it; Serra, E.; Pallozzi, V.

2015-06-23

Since industrial revolution, human activities drive towards unsustainable global economy due to the overexploitation of natural resources and the unacceptable emissions of pollution and greenhouse gases. In order to address that issue, engineering research has been focusing on gas sensors development for monitoring gas emissions and controlling the combustion process sustainability. Semiconductors metal oxides sensors are attractive technology because they require simple design and fabrication, involving high accessibility, small size and low cost. Perovskite oxides are the most promising sensing materials because sensitivity, selectivity, stability and speed-response can be modulated and optimized by changing the chemical composition. One of themore » most convenient synthesis process of perovskite is the citrate-nitrate auto-combustion method, in which nitrate is the oxidizing agent and citrate is the fuel and the chelating argent in the same time. Since the sensibility of perovskite oxides depends on the defective crystallographic structure and the nanomorphology, the experimental was designed in order to study the dependence of powder properties on the synthesis conditions, such as the solution acidity and the relative amount of metals, nitrates and citric acid. Crystalline structure was studied in depth for defining the effects of synthesis conditions on size, morphology and crystallographic structure of nanopowders of LaFeO{sub 3}.« less

Combustion synthesis of LaFeO3 sensing nanomaterial

NASA Astrophysics Data System (ADS)

Zaza, F.; Pallozzi, V.; Serra, E.; Pasquali, M.

2015-06-01

Since industrial revolution, human activities drive towards unsustainable global economy due to the overexploitation of natural resources and the unacceptable emissions of pollution and greenhouse gases. In order to address that issue, engineering research has been focusing on gas sensors development for monitoring gas emissions and controlling the combustion process sustainability. Semiconductors metal oxides sensors are attractive technology because they require simple design and fabrication, involving high accessibility, small size and low cost. Perovskite oxides are the most promising sensing materials because sensitivity, selectivity, stability and speed-response can be modulated and optimized by changing the chemical composition. One of the most convenient synthesis process of perovskite is the citrate-nitrate auto-combustion method, in which nitrate is the oxidizing agent and citrate is the fuel and the chelating argent in the same time. Since the sensibility of perovskite oxides depends on the defective crystallographic structure and the nanomorphology, the experimental was designed in order to study the dependence of powder properties on the synthesis conditions, such as the solution acidity and the relative amount of metals, nitrates and citric acid. Crystalline structure was studied in depth for defining the effects of synthesis conditions on size, morphology and crystallographic structure of nanopowders of LaFeO3.

Composition of highly concentrated silicate electrolytes and ultrasound influencing the plasma electrolytic oxidation of magnesium

NASA Astrophysics Data System (ADS)

Simchen, F.; Rymer, L.-M.; Sieber, M.; Lampke, T.

2017-03-01

Magnesium and its alloys are increasingly in use as lightweight construction materials. However, their inappropriate corrosion and wear resistance often prevent their direct practical use. The plasma electrolytic oxidation (PEO) is a promising, environmentally friendly method to improve the surface characteristics of magnesium materials by the formation of oxide coatings. These PEO layers contain components of the applied electrolyte and can be shifted in their composition by increasing the concentration of the electrolyte constituents. Therefore, in contrast to the use of conventional low concentrated electrolytes, the process results in more stable protective coatings, in which electrolyte species are the dominating constitutes. In the present work, the influence of the composition of highly concentrated alkaline silicate electrolytes with additives of phosphate and glycerol on the quality of PEO layers on the magnesium alloy AZ31 was examined. The effect of ultrasound coupled into the electrolyte bath was also considered. The process was monitored by recording the electrical process variables with a transient recorder and by observation of the discharge phenomena on the sample surface with a camera. The study was conducted on the basis of a design of experiments. The effects of the process parameter variation are considered with regard to the coatings thickness, hardness and corrosion resistance. Information about the statistical significance of the effects of the parameters on the considered properties is obtained by an analysis of variance (ANOVA).

Hemodynamic and oxidative mechanisms of tourniquet-induced muscle injury: near-infrared spectroscopy for the orthopedics setting

NASA Astrophysics Data System (ADS)

Shadgan, Babak; Reid, W. Darlene; Harris, R. Luke; Jafari, Siavash; Powers, Scott K.; O'Brien, Peter J.

2012-08-01

During orthopedic procedures, the tourniquets used to maintain bloodless surgical fields cause ischemia and then reperfusion (I/R), leading to oxidative muscle injury. Established methods exist neither for monitoring orthopedic I/R nor for predicting the extent of tourniquet-associated oxidative injury. To develop a predictive model for tourniquet-associated oxidative muscle injury, this study combined real-time near-infrared spectroscopy (NIRS) monitoring of I/R with Western blotting (WB) for oxidized proteins. We hypothesized strong correlations between NIRS-derived I/R indices and muscle protein oxidation. In 17 patients undergoing ankle fracture repair, a thigh tourniquet was inflated on the injured limb (300 mmHg). Using a continuous-wave (CW) NIRS setup, oxygenated (O2Hb), deoxygenated (HHb), and total (tHb) hemoglobin were monitored bilaterally (tourniquet versus control) in leg muscles. Leg muscle biopsies were collected unilaterally (tourniquet side) immediately after tourniquet inflation (pre) and before deflation (post). Average ischemia duration was 43.2±14.6 min. In post-compared to pre-biopsies, muscle protein oxidation (quantified using WB) increased 172.3%±145.7% (P<0.0005). Changes in O2Hb and tHb were negatively correlated with protein oxidation (respectively: P=0.040, R2=0.25 and P=0.003, R2=0.58). Reoxygenation rate was positively correlated with protein oxidation (P=0.041, R2=0.25). These data indicate that using CW NIRS, it is possible to predict orthopedic tourniquet-associated muscle oxidative injury noninvasively.

OH-initiated heterogeneous aging of highly oxidized organic aerosol

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

Kessler, Sean H.; Nah, Theodora; Daumit, Kelly E.

2011-12-05

The oxidative evolution (“aging”) of organic species in the atmosphere is thought to have a major influence on the composition and properties of organic particulate matter, but remains poorly understood, particularly for the most oxidized fraction of the aerosol. Here we measure the kinetics and products of the heterogeneous oxidation of highly oxidized organic aerosol, with an aim of better constraining such atmospheric aging processes. Submicron particles composed of model oxidized organics—1,2,3,4-butanetetracarboxylic acid (C{sub 8}H{sub 10}O{sub 8}), citric acid (C{sub 6}H{sub 8}O{sub 7}), tartaric acid (C{sub 4}H{sub 6}O{sub 6}), and Suwannee River fulvic acid—were oxidized by gas-phase OH in amore » flow reactor, and the masses and elemental composition of the particles were monitored as a function of OH exposure. In contrast to our previous studies of less-oxidized model systems (squalane, erythritol, and levoglucosan), particle mass did not decrease significantly with heterogeneous oxidation. Carbon content of the aerosol always decreased somewhat, but this mass loss was approximately balanced by an increase in oxygen content. The estimated reactive uptake coefficients of the reactions range from 0.37 to 0.51 and indicate that such transformations occur at rates corresponding to 1-2 weeks in the atmosphere, suggesting their importance in the atmospheric lifecycle of organic particulate matter.« less

Label-free monitoring of cell death induced by oxidative stress in living human cells using terahertz ATR spectroscopy

PubMed Central

Zou, Yi; Liu, Qiao; Yang, Xia; Huang, Hua-Chuan; Li, Jiang; Du, Liang-Hui; Li, Ze-Ren; Zhao, Jian-Heng; Zhu, Li-Guo

2017-01-01

We demonstrated that attenuated total reflectance terahertz time-domain spectroscopy (ATR THz-TDS) is able to monitor oxidative stress response of living human cells, which is proven in this work that it is an efficient non-invasive, label-free, real-time and in situ monitoring of cell death. Furthermore, the dielectric constant and dielectric loss of cultured living human breast epithelial cells, and along with their evolution under oxidative stress response induced by high concentration of H2O2, were quantitatively determined in the work. Our observation and results were finally confirmed using standard fluorescence-labeled flow cytometry measurements and visible fluorescence imaging. PMID:29359084

Comparative Evaluation of Diagnostic Tools for Oxidative Deterioration of Polyunsaturated Fatty Acid-Enriched Infant Formulas during Storage

PubMed Central

Siefarth, Caroline; Serfert, Yvonne; Drusch, Stephan; Buettner, Andrea

2013-01-01

The challenge in the development of infant formulas enriched with polyunsaturated fatty acids (PUFAs) is to meet the consumers’ expectations with regard to high nutritional and sensory value. In particular, PUFAs may be prone to fatty acid oxidation that can generate potential rancid, metallic and/or fishy off-flavors. Although such off-flavors pose no health risk, they can nevertheless lead to rejection of products by consumers. Thus, monitoring autoxidation at its early stages is of great importance and finding a suitable analytical tool to perform these evaluations is therefore of high interest in quality monitoring. Two formulations of infant formulas were varied systematically in their mineral composition and their presence of antioxidants to produce 18 model formulas. All models were aged under controlled conditions and their oxidative deterioration was monitored. A quantitative study was performed on seven characteristic odor-active secondary oxidation products in the formulations via two-dimensional high resolution gas chromatography-mass spectrometry/olfactometry (2D-HRGC-MS/O). The sensitivity of the multi-dimensional GC-MS/O analysis was supported by two additional analytical tools for monitoring autoxidation, namely the analysis of lipid hydroperoxides and conjugated dienes. Furthermore, an aroma profile analysis (APA) was performed to reveal the presence and intensities of typical odor qualities generated in the course of fatty acid oxidation. The photometrical analyses of lipid hydroperoxides and conjugated dienes were found to be too insensitive for early indication of the development of sensory defects. By comparison, the 2D-HRGC-MS/O was capable of monitoring peroxidation of PUFAs at low ppb-level in its early stages. Thereby, it was possible to screen oxidative variances on the basis of such volatile markers already within eight weeks after production of the products, which is an earlier indication of oxidative deterioration than achievable via conventional methods. In detail, oxidative variances between the formulations revealed that lipid oxidation was low when copper was administered in an encapsulated form and when antioxidants (vitamin E, ascorbyl palmitate) were present. PMID:28234303

Complete removal of AHPS synthetic dye from water using new electro-fenton oxidation catalyzed by natural pyrite as heterogeneous catalyst.

PubMed

Labiadh, Lazhar; Oturan, Mehmet A; Panizza, Marco; Hamadi, Nawfel Ben; Ammar, Salah

2015-10-30

The mineralization of a new azo dye - the (4-amino-3-hydroxy-2-p-tolylazo-naphthalene-1-sulfonic acid) (AHPS) - has been studied by a novel electrochemical advanced oxidation process (EAOP), consisting in electro-Fenton (EF) oxidation, catalyzed by pyrite as the heterogeneous catalyst - the so-called 'pyrite-EF'. This solid pyrite used as heterogeneous catalyst instead of a soluble iron salt, is the catalyst the system needs for production of hydroxyl radicals. Experiments were performed in an undivided cell equipped with a BDD anode and a commercial carbon felt cathode to electrogenerate in situ H2O2 and regenerate ferrous ions as catalyst. The effects on operating parameters, such as applied current, pyrite concentration and initial dye content, were investigated. AHPS decay and mineralization efficiencies were monitored by HPLC analyses and TOC measurements, respectively. Experimental results showed that AHPS was quickly oxidized by hydroxyl radicals (OH) produced simultaneously both on BDD surface by water discharge and in solution bulk from electrochemically assisted Fenton's reaction with a pseudo-first-order reaction. AHPS solutions with 175 mg L(-1) (100 mg L(-1) initial TOC) content were then almost completely mineralized in 8h. Moreover, the results demonstrated that, under the same conditions, AHPS degradation by pyrite electro-Fenton process was more powerful than the conventional electro-Fenton process. Copyright © 2015 Elsevier B.V. All rights reserved.

Carbonylation of milk powder proteins as a consequence of processing conditions.

PubMed

Fenaille, François; Parisod, Véronique; Tabet, Jean-Claude; Guy, Philippe A

2005-08-01

During industrial treatments, milk proteins could be oxidatively modified, thus leading to the formation of modified/oxidised amino acid residues. The apparition of such modified residues may contribute to the formation of new immunologically reactive structures. Some of these adducts could, in an advanced stage, lead to cross-linked protein species whose proteolytic susceptibility would be drastically decreased. Such protein species, that are resistant to digestion, could also constitute major food allergens. Therefore, these oxidative protein modifications tend to increase the natural allergenicity of milk proteins. For these reasons, monitoring milk protein oxidative modifications could be very useful regarding both product quality and allergenicity issues. In the present paper, we highlight, using different analytical approaches, the preferential carbonylation of beta-lactoglobulin (beta-Lg) during industrial treatments of milk. This result is particularly interesting since native beta-Lg represents one of the major milk allergens.

Interfacial stability of ultrathin films of magnetite Fe3O4 (111) on Al2O3(001) grown by ozone-assisted molecular-beam epitaxy

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

Hong, Hawoong; Kim, Jongjin; Fang, Xinyue

Thin films of iron oxides including magnetite (Fe3O4) and hematite (α-Fe2O3) have many important applications. Both forms of oxide can occur naturally during film growth by iron deposition under various oxidation environment; an important issue is to understand and control the process resulting in a single-phase film. We have performed in-situ real-time studies using x-ray diffraction of such film growth on sapphire (001) under pure ozone by monitoring the (00L) rod. Stable magnetite growth can be maintained at growth temperatures below 600° C up to a certain critical film thickness, beyond which the growth becomes hematite. The results demonstrate themore » importance of interfacial interaction in stabilizing the magnetite phase.« less

40 CFR 63.5994 - How do I conduct tests and procedures for tire production affected sources?

Code of Federal Regulations, 2014 CFR

2014-07-01

... oxidizer, monitor the firebox secondary chamber temperature. (ii) If you use a carbon adsorber, monitor the total regeneration stream mass or volumetric flow for each regeneration cycle, and the carbon bed... control device other than a thermal oxidizer or a regenerative carbon adsorber, install and operate a...

40 CFR Table Hh-4 to Subpart Hh of... - Landfill Methane Oxidation Fractions

Code of Federal Regulations, 2014 CFR

2014-07-01

... gas sent off-site). If a single monitoring location is used to monitor volumetric flow and CH4... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Landfill Methane Oxidation Fractions... (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Municipal Solid Waste Landfills Pt...

Mechanism and toxicity research of benzalkonium chloride oxidation in aqueous solution by H2O2/Fe(2+) process.

PubMed

Zhang, Qian; Xia, Yu-Feng; Hong, Jun-Ming

2016-09-01

As widely used disinfectants, the pollution caused by benzalkonium chloride (BAC) has attracted a lot of attention in recent years. Since it is not suitable for biodegradation, BAC was degraded firstly by Fenton advanced oxidation technologies (AOTs) in this research to enhance the biodegradability of the pollutions. The result revealed that the optimal molar ratio of H2O2/Fe(2+) for BAC degradation was 10:1, and the COD removal rate was 32 %. To clarify the pathway of degradation, the technique of GC-MS was implemented herein to identify intermediates and the toxicity of those BAC intermediates were also novelty tested through microbial fuel cells (MFC). The findings indicated that ten transformation products including benzyl dimethyl amine and dodecane were formed during the H2O2/Fe(2+) processes, which means the degradation pathway of BAC was initiated both on the hydrophobic (alkyl chain) and hydrophilic (benzyl and ammonium moiety) region of the surfactant. The toxicity of BAC before and after treated by Fenton process was monitored through MFC system. The electricity generation was improved 337 % after BAC was treated by H2O2/Fe(2+) oxidation processes which indicated that the toxicity of those intermediates were much lower than BAC. The mechanism and toxicity research in this paper could provide the in-depth understanding to the pathway of BAC degradation and proved the possibility of AOTs for the pretreatment of a biodegradation process.

High temperature cooling system and method

DOEpatents

Loewen, Eric P.

2006-12-12

A method for cooling a heat source, a method for preventing chemical interaction between a vessel and a cooling composition therein, and a cooling system. The method for cooling employs a containment vessel with an oxidizable interior wall. The interior wall is oxidized to form an oxide barrier layer thereon, the cooling composition is monitored for excess oxidizing agent, and a reducing agent is provided to eliminate excess oxidation. The method for preventing chemical interaction between a vessel and a cooling composition involves introducing a sufficient quantity of a reactant which is reactive with the vessel in order to produce a barrier layer therein that is non-reactive with the cooling composition. The cooling system includes a containment vessel with oxidizing agent and reducing agent delivery conveyances and a monitor of oxidation and reduction states so that proper maintenance of a vessel wall oxidation layer occurs.

Methane Transmission and Oxidation throughout the Soil Column from Three Central Florida Sites

NASA Astrophysics Data System (ADS)

Bond-Lamberty, B. P.; Fansler, S.; Becker, K. E.; Hinkle, C. R.; Bailey, V. L.

2015-12-01

When methane (CH4) is generated in anoxic soil sites, it may be subsequently re-oxidized to carbon dioxide (CO2). Understanding the controls on, and magnitudes of, these processes is necessary to accurately represent greenhouse gas production and emission from soils. We used a laboratory incubation to examine the influence of variable conditions on methane transmission and oxidation, and identify critical reaction zones throughout the soil column. Sandy soils were sampled from three different sites at Disney Wilderness Preserve (DWP), Florida, USA: a depression marsh characterized by significant surface organic matter accumulation, a dry pine flatwood site with water intrusion and organic horizon at depth (200+ cm); and an intermediate-drainage site. Contiguous, 30-cm long cores were sampled from N=4 random boreholes at each site, from the surface to the water table (varying from 90 to 240 cm). In the lab, each core was monitored for 50 hours to quantify baseline (pretreatment) gas fluxes before injection with 6 ml CH4 (an amount commensurate with previous field collar measurements) at the base of each core. We then monitored CH4 and CO2 evolution for 100 hours after injection, calculating per-gas and total C evolution. Methane emissions spiked ~10 hours after injection for all cores, peaking at 0.001 μmol/g soil/hr, ~30x larger than pre-injection flux rates. On a C basis, CO2 emissions were orders of magnitude larger, and rose significantly after injection, with elevated rates generally sustained throughout the incubation. Cores from the depression marsh and shallower depths had significantly higher fluxes of both gases. We estimate that 99.1% of the original CH4 injection was oxidized to CO2. These findings suggest either that the methane measured in the field at DWP originates from within a few centimeters of the surface, or that it is produced in much larger quantities deeper in the profile before most is subsequently oxidized. This highlights the need for better understanding and modeling the multiple processes that result in soil-atmosphere CO2 and CH4 fluxes.

XRD monitoring of α self-irradiation in uranium-americium mixed oxides.

PubMed

Horlait, Denis; Lebreton, Florent; Roussel, Pascal; Delahaye, Thibaud

2013-12-16

The structural evolution under (241)Am self-irradiation of U(1-x)Am(x)O(2±δ) transmutation fuels (with x ≤ 0.5) was studied by X-ray diffraction (XRD). Samples first underwent a preliminary heat treatment performed under a reducing atmosphere (Ar/H2(4%)) aiming to recover the previously accumulated structural defects. Over all measurements (carried out over up to a full year and for integrated doses up to 1.5 × 10(18) α-decay events·g(-1)), only fluorite U(1-x)Am(x)O(2±δ) solid solutions were observed. Within a few days after the end of the heat treatment, each of the five studied samples was slowly oxidized as a consequence of their move to air atmosphere, which is evidenced by XRD by an initial sharp decrease of the unit cell parameter. For the compounds with x ≤ 0.15, this oxidation occurred without any phase transitions, but for U0.6Am0.4O(2±δ) and U0.5Am0.5O(2±δ), this process is accompanied by a transition from a first fluorite solid solution to a second oxidized one, as the latter is thermodynamically stable in ambient conditions. In the meantime and after the oxidation process, (241)Am α self-irradiation caused a structural swelling up to ∼0.8 vol %, independently of the sample composition. The kinetic constants of swelling were also determined by regression of experimental data and are, as expected, dependent on x and thus on the dose rate. The normalization of these kinetic constants by sample α-activity, however, leads to very close swelling rates among the samples. Finally, evolutions of microstrain and crystallite size were also monitored, but for the considered dose rates and cumulated doses, α self-irradiation was found, within the limits of the diffractometer used, to have almost no impact on these characteristics. Microstrain was found to be influenced instead by the americium content in the materials (i.e., by the impurities associated with americium starting material and the increase of cationic charge heterogeneity with increasing americium content).

Real-time measurement of reactive gases (NO, NO2, O3, CO) at ERSA, Cape Corsica, a long term Observatory.

NASA Astrophysics Data System (ADS)

Pichon, Jean-Marc; Colomb, Aurelie; Gheusi, Francois; Sauvage, Stephane; Pont, Veronique; Tison, Emmanuel; Bordier, Florent; Grignion, Guillaume; Savelli, Jean-Luc; Dulac, Francois; Sciare, Jean; Nicolas, Jose; Bourrianne, Thierry; Bouvier, Laetitia

2013-04-01

Important efforts have been put in 2012 in order to implement the infrastructure and instrumentation for a fully equipped background monitoring station at Ersa, Cape Corsica, key location at the crossroads of dusty southerly airmasses and polluted outflows from the European continent. The ERSA observatory is a french initiative within the framework of CHARMEX (Chemistry-Aerosol Mediterranean Experiment (ChArMEx, http://charmex.lsce.ipsl.fr/) and CORSICA (Centre d'Observation Régional pour la Surveillance du Climat et de l'environnement Atmosphérique et océanographique en Méditerranée occidentale (http://www2.obs-mip.fr/corsica) . The measurements of the station include real-time measurement of reactive gases (O3, CO, NO, NO2), off-line VOC measurements (cylinders, cartridges), a broad spectrum of aerosol properties (chemical composition, ground optical properties, integrated and space-resolved optical properties , size distribution properties, mass, hygroscopicity as well as dry/wet depositions). Among all the parameters, reactive gases are recognized as precursors of ozone and aerosol. The primarily emitted nitrogen oxides (NOx=NO+NO2) have a substantial impact on radical chemistry, ozone (O3) formation and aerosol by their atmospheric oxidation to aerosol nitrate. Carbon monoxide (CO) is mostly primarily emitted from combustion processes, but it is also formed in substantial amounts from the oxidation of methane (CH4) and volatile organic compounds (VOCs). Due to its high global turn-over rates CO is a major O3 precursor, and it has a strong impact on the oxidizing capacity and thus indirectly on the concentration of the climate gas CH4. O3 is a climate gas itself, however, also strongly involved in NO/NO2 partitioning and oxidizing capacity, thus coupling back on several photochemical processes. Accordingly, impacts on climate are multiple and rather complex. The understanding requires high quality, long-term observations of these reactive species. We present here the first measurement of reactive gases (O3, CO, NO, NO2) obtained at ERSA, the new monitoring station at Cape Corsica.

First results of tall tower based nitrous oxide flux monitoring over an agricultural region in Central Europe

NASA Astrophysics Data System (ADS)

Haszpra, László; Hidy, Dóra; Taligás, Tímea; Barcza, Zoltán

2018-03-01

Nitrous oxide is one of the atmospheric greenhouse gases whose amount is significantly influenced by human activity. Its major anthropogenic sources are the agricultural soils but the emission is known only with large uncertainty yet. The paper presents a tall tower based measuring system installed in Hungary, which is designed for the long-term monitoring of nitrous oxide emission of a regionally typical composition of agricultural fields by means of eddy covariance technique. Due to the careful calibration of the gas analyzer applied the measuring system is also suitable for the recording of the atmospheric concentration of nitrous oxide on the globally compatible scale (WMO X2006A). The paper reports the results of the first two years of the monitoring program, which is the first of its kind in Central Europe. For the period of July 2015-June 2017 the concentration measurements indicate an increasing trend of 0.91 nmol mol-1 year-1 with an average concentration of 330.64 nmol mol-1. During the two years of the project, the monitoring system recorded a total of 441 ± 195 mg N2O-N m-2 nitrous oxide emission with late spring/early summer maximum. The measurements also revealed the episodic nature of the emission typically triggered by major precipitation events.

Sensing Free Sulfur Dioxide in Wine

PubMed Central

Monro, Tanya M.; Moore, Rachel L.; Nguyen, Mai-Chi; Ebendorff-Heidepriem, Heike; Skouroumounis, George K.; Elsey, Gordon M.; Taylor, Dennis K.

2012-01-01

Sulfur dioxide (SO2) is important in the winemaking process as it aids in preventing microbial growth and the oxidation of wine. These processes and others consume the SO2 over time, resulting in wines with little SO2 protection. Furthermore, SO2 and sulfiting agents are known to be allergens to many individuals and for that reason their levels need to be monitored and regulated in final wine products. Many of the current techniques for monitoring SO2 in wine require the SO2 to be separated from the wine prior to analysis. This investigation demonstrates a technique capable of measuring free sulfite concentrations in low volume liquid samples in white wine. This approach adapts a known colorimetric reaction to a suspended core optical fiber sensing platform, and exploits the interaction between guided light located within the fiber voids and a mixture of the wine sample and a colorimetric analyte. We have shown that this technique enables measurements to be made without dilution of the wine samples, thus paving the way towards real time in situ wine monitoring. PMID:23112627

Automatic crack detection and classification method for subway tunnel safety monitoring.

PubMed

Zhang, Wenyu; Zhang, Zhenjiang; Qi, Dapeng; Liu, Yun

2014-10-16

Cracks are an important indicator reflecting the safety status of infrastructures. This paper presents an automatic crack detection and classification methodology for subway tunnel safety monitoring. With the application of high-speed complementary metal-oxide-semiconductor (CMOS) industrial cameras, the tunnel surface can be captured and stored in digital images. In a next step, the local dark regions with potential crack defects are segmented from the original gray-scale images by utilizing morphological image processing techniques and thresholding operations. In the feature extraction process, we present a distance histogram based shape descriptor that effectively describes the spatial shape difference between cracks and other irrelevant objects. Along with other features, the classification results successfully remove over 90% misidentified objects. Also, compared with the original gray-scale images, over 90% of the crack length is preserved in the last output binary images. The proposed approach was tested on the safety monitoring for Beijing Subway Line 1. The experimental results revealed the rules of parameter settings and also proved that the proposed approach is effective and efficient for automatic crack detection and classification.

Electrical Resistance Technique to Monitor SiC Composite Detection

NASA Technical Reports Server (NTRS)

Smith, Craig; Morscher, Gregory; Xia, Zhenhai

2008-01-01

Ceramic matrix composites are suitable for high temperature structural applications such as turbine airfoils and hypersonic thermal protection systems. The employment of these materials in such applications is limited by the ability to process components reliable and to accurately monitor and predict damage evolution that leads to failure under stressed-oxidation conditions. Current nondestructive methods such as ultrasound, x-ray, and thermal imaging are limited in their ability to quantify small scale, transverse, in-plane, matrix cracks developed over long-time creep and fatigue conditions. Electrical resistance of SiC/SiC composites is one technique that shows special promise towards this end. Since both the matrix and the fibers are conductive, changes in matrix or fiber properties should relate to changes in electrical conductivity along the length of a specimen or part. The effect of matrix cracking on electrical resistivity for several composite systems will be presented and some initial measurements performed at elevated temperatures under stress-rupture conditions. The implications towards electrical resistance as a technique applied to composite processing, damage detection (health monitoring), and life-modeling will be discussed.

Automatic Crack Detection and Classification Method for Subway Tunnel Safety Monitoring

PubMed Central

Zhang, Wenyu; Zhang, Zhenjiang; Qi, Dapeng; Liu, Yun

2014-01-01

Cracks are an important indicator reflecting the safety status of infrastructures. This paper presents an automatic crack detection and classification methodology for subway tunnel safety monitoring. With the application of high-speed complementary metal-oxide-semiconductor (CMOS) industrial cameras, the tunnel surface can be captured and stored in digital images. In a next step, the local dark regions with potential crack defects are segmented from the original gray-scale images by utilizing morphological image processing techniques and thresholding operations. In the feature extraction process, we present a distance histogram based shape descriptor that effectively describes the spatial shape difference between cracks and other irrelevant objects. Along with other features, the classification results successfully remove over 90% misidentified objects. Also, compared with the original gray-scale images, over 90% of the crack length is preserved in the last output binary images. The proposed approach was tested on the safety monitoring for Beijing Subway Line 1. The experimental results revealed the rules of parameter settings and also proved that the proposed approach is effective and efficient for automatic crack detection and classification. PMID:25325337

Optimal Design and Operation of In-Situ Chemical Oxidation Using Stochastic Cost Optimization Toolkit

NASA Astrophysics Data System (ADS)

Kim, U.; Parker, J.; Borden, R. C.

2014-12-01

In-situ chemical oxidation (ISCO) has been applied at many dense non-aqueous phase liquid (DNAPL) contaminated sites. A stirred reactor-type model was developed that considers DNAPL dissolution using a field-scale mass transfer function, instantaneous reaction of oxidant with aqueous and adsorbed contaminant and with readily oxidizable natural oxygen demand ("fast NOD"), and second-order kinetic reactions with "slow NOD." DNAPL dissolution enhancement as a function of oxidant concentration and inhibition due to manganese dioxide precipitation during permanganate injection are included in the model. The DNAPL source area is divided into multiple treatment zones with different areas, depths, and contaminant masses based on site characterization data. The performance model is coupled with a cost module that involves a set of unit costs representing specific fixed and operating costs. Monitoring of groundwater and/or soil concentrations in each treatment zone is employed to assess ISCO performance and make real-time decisions on oxidant reinjection or ISCO termination. Key ISCO design variables include the oxidant concentration to be injected, time to begin performance monitoring, groundwater and/or soil contaminant concentrations to trigger reinjection or terminate ISCO, number of monitoring wells or geoprobe locations per treatment zone, number of samples per sampling event and location, and monitoring frequency. Design variables for each treatment zone may be optimized to minimize expected cost over a set of Monte Carlo simulations that consider uncertainty in site parameters. The model is incorporated in the Stochastic Cost Optimization Toolkit (SCOToolkit) program, which couples the ISCO model with a dissolved plume transport model and with modules for other remediation strategies. An example problem is presented that illustrates design tradeoffs required to deal with characterization and monitoring uncertainty. Monitoring soil concentration changes during ISCO was found to be important to avoid decision errors associated with slow rebound of groundwater concentrations.

Proteome-wide detection and quantitative analysis of irreversible cysteine oxidation using long column UPLC-pSRM.

PubMed

Lee, Chia-Fang; Paull, Tanya T; Person, Maria D

2013-10-04

Reactive oxygen species (ROS) play an important role in normal biological functions and pathological processes. ROS is one of the driving forces for oxidizing proteins, especially on cysteine thiols. The labile, transient, and dynamic nature of oxidative modifications poses enormous technical challenges for both accurate modification site determination and quantitation of cysteine thiols. The present study describes a mass spectrometry-based approach that allows effective discovery and quantification of irreversible cysteine modifications. The utilization of a long reverse phase column provides high-resolution chromatography to separate different forms of modified cysteine thiols from protein complexes or cell lysates. This Fourier transform mass spectrometry (FT-MS) approach enabled detection and quantitation of ataxia telangiectasia mutated (ATM) complex cysteine sulfoxidation states using Skyline MS1 filtering. When we applied the long column ultra high pressure liquid chromatography (UPLC)-MS/MS analysis, 61 and 44 peptides from cell lysates and cells were identified with cysteine modifications in response to in vitro and in vivo H2O2 oxidation, respectively. Long column ultra high pressure liquid chromatography pseudo selected reaction monitoring (UPLC-pSRM) was then developed to monitor the oxidative level of cysteine thiols in cell lysate under varying concentrations of H2O2 treatment. From UPLC-pSRM analysis, the dynamic conversion of sulfinic (S-O2H) and sulfonic acid (S-O3H) was observed within nucleoside diphosphate kinase (Nm23-H1) and heat shock 70 kDa protein 8 (Hsc70). These methods are suitable for proteome-wide studies, providing a highly sensitive, straightforward approach to identify proteins containing redox-sensitive cysteine thiols in biological systems.

Comparative study of the effect of pharmaceutical additives on the elimination of antibiotic activity during the treatment of oxacillin in water by the photo-Fenton, TiO2-photocatalysis and electrochemical processes.

PubMed

Serna-Galvis, Efraim A; Silva-Agredo, Javier; Giraldo, Ana L; Flórez-Acosta, Oscar A; Torres-Palma, Ricardo A

2016-01-15

Synthetic pharmaceutical effluents loaded with the β-lactam antibiotic oxacillin were treated using advanced oxidation processes (the photo-Fenton system and TiO2 photocatalysis) and chloride mediated electrochemical oxidation (with Ti/IrO2 anodes). Combinations of the antibiotic with excipients (mannitol or tartaric acid), an active ingredient (calcium carbonate, i.e. bicarbonate ions due to the pH) and a cleaning agent (sodium lauryl ether sulfate) were considered. Additionally, urban wastewater that had undergone biological treatment was doped with oxacillin and treated with the tested systems. The evolution of antimicrobial activity was monitored as a parameter of processes efficiency. Although the two advanced oxidation processes (AOPs) differ only in the way they produce OH, marked differences were observed between them. There were also differences between the AOPs and the electrochemical system. Interestingly, each additive had a different effect on each treatment. For water loaded with mannitol, electrochemical treatment was the most suitable option because the additive did not significantly affect the efficiency of the system. Due to the formation of a complex with Fe(3+), tartaric acid accelerated the elimination of antibiotic activity during the photo-Fenton process. For TiO2 photocatalysis, the presence of bicarbonate ions contributed to antibiotic activity elimination through the possible formation of carbonate and bicarbonate radicals. Sodium lauryl ether sulfate negatively affected all of the processes. However, due to the higher selectivity of HOCl compared with OH, electrochemical oxidation showed the least inhibited efficiency. For the urban wastewater doped with oxacillin, TiO2 photocatalysis was the most efficient process. These results will help select the most suitable technology for the treatment of water polluted with β-lactam antibiotics. Copyright © 2015 Elsevier B.V. All rights reserved.

Particle beam experiments for the analysis of reactive sputtering processes in metals and polymer surfaces

NASA Astrophysics Data System (ADS)

Corbella, Carles; Grosse-Kreul, Simon; Kreiter, Oliver; de los Arcos, Teresa; Benedikt, Jan; von Keudell, Achim

2013-10-01

A beam experiment is presented to study heterogeneous reactions relevant to plasma-surface interactions in reactive sputtering applications. Atom and ion sources are focused onto the sample to expose it to quantified beams of oxygen, nitrogen, hydrogen, noble gas ions, and metal vapor. The heterogeneous surface processes are monitored in situ by means of a quartz crystal microbalance and Fourier transform infrared spectroscopy. Two examples illustrate the capabilities of the particle beam setup: oxidation and nitriding of aluminum as a model of target poisoning during reactive magnetron sputtering, and plasma pre-treatment of polymers (PET, PP).

An electrochemical approach to monitor pH change in agar media during plant tissue culture.

PubMed

Wang, Min; Ha, Yang

2007-05-15

In this work, metal oxide microelectrodes were developed to monitor pH change in agar media during plant tissue culture. An antimony wire was produced by a new approach "capillary melt method". The surface of the obtained antimony wire was oxidized in a potassium nitrate melt to fabricate an antimony oxide film for pH sensing. Characterization results show that the oxide layer grown on the wire surface consists of Sb(2)O(3) crystal phase. The sensing response, open-circuit potential, of the electrode has a good linear relationship (R(2)=1.00) with pH value of the test solution. Adding organic compounds into the test media would not affect the linear relationship, although the slope of the lines varied with different ingredients added. The antimony oxide electrodes were employed to continuously monitor pH change of agar culture media during a 2-week plant tissue culture of Dendrobium candidum. The antimony oxide electrode fabricated this way has the advantages of low cost, easy fabrication, fast response, and almost no contamination introduced into the system. It would be suitable for in situ and continuous pH measurement in many bio applications.

Sonocatalytic degradation of malachite green oxalate by a semiconductor metal oxide nanocatalyst.

PubMed

Bhavani, R; Sivasamy, A

2016-12-01

Advanced Oxidation Process (AOP) technologies are considered to be better technique for the degradation or mineralization of many recalcitrant compounds and pollutants. In the present study heterogeneous sonocatalytic degradation of a model organic compound such as Malachite green oxalate (MGO) was carried out in the aqueous phase. Zinc oxide nanorods were prepared by precipitation method employing zinc acetates as precursors and were characterized by FT-IR, XRD, FE-SEM and EDAX analysis. Degradation of MGO in the aqueous phase was studied in detail under the sonocatalytic process. Effects of pH, dye concentration, oxidant concentration, kinetics and effect of electrolytes on dye degradation were carried out to check the efficiency of the sonocatalyst. Effect of energy input on the degradation processes was also investigated. The degradation of dye molecules were monitored by UV-visible spectrophotometer and Chemical Oxygen demand (COD). The dye molecules were readily degraded at above 90% in the pH range 5.0-7.0 under ultrasound with zinc oxide nanorods. The interference of electrolytes like NaCl, KCl, Na 2 CO 3 , NaHCO 3 and MgSO 4 on the degradation of dye molecules were also studied on the sonocatalytic degradation of MGO. From the kinetic studies it was observed that at lower initial concentration of dye molecules the degradation efficiency was above 90%. The rate of the reaction decreased on increasing the initial dye concentrations of the dye molecules. It was observed that the complete mineralization of dye molecules was achieved without the formation of toxic by-products. The reusability of the catalyst also showed the effective degradation of the dye molecules up to five cycles without loss of the catalytic activities. Copyright © 2015 Elsevier Inc. All rights reserved.

Nanocrystalline semiconductor doped rare earth oxide for the photocatalytic degradation studies on Acid Blue 113: A di-azo compound under UV slurry photoreactor.

PubMed

Suganya Josephine, G A; Mary Nisha, U; Meenakshi, G; Sivasamy, A

2015-11-01

Preventive measures for the control of environmental pollution and its remediation has received much interest in recent years due to the world-wide increase in the contamination of water bodies. Contributions of these harmful effluents are caused by the leather processing, pharmaceutical, cosmetic, textile, agricultural and other chemical industries. Nowadays, advanced oxidation processes considered to be better option for the complete destruction of organic contaminants in water and wastewater. Acid Blue 113 is a most widely used di-azo compound in leather, textile, dying and food industry as a color rending compound. In the present study, we have reported the photo catalytic degradation of Acid Blue 113 using a nanocrystalline semiconductor doped rare earth oxide as a photo catalyst under UV light irradiation. The photocatalyst was prepared by a simple precipitation technique and were characterized by XRD, FT-IR, UV-DRS and FE-SEM analysis. The experimental results proved that the prepared photo catalyst was nanocrystalline and highly active in the UV region. The UV-DRS results showed the band gap energy was 3.15eV for the prepared photo catalyst. The photodegradation efficiency was analyzed by various experimental parameters such as pH, catalyst dosage, variation of substrate concentration and effect of electrolyte addition. The photo degradation process followed a pseudo first order kinetics and was continuously monitored by UV-visible spectrophotometer. The experimental results proved the efficacy of the nanocrystalline zinc oxide doped dysprosium oxide which are highly active under UV light irradiations. It is also suggested that the prepared material would find wider applications in environmental remediation technologies to remove the carcinogenic and toxic moieties present in the industrial effluents. Copyright © 2015 Elsevier Inc. All rights reserved.

Tryptophan and Cysteine Oxidation Products Dominate in α-Lactalbumin-Derived Peptides Analyzed with LC-MSn.

PubMed

Koivumäki, Tuuli P; Gürbüz, Göker; Heinonen, I Marina

2017-09-01

α-Lactalbumin (α-La), a major milk whey protein, is comprised of several amino acids prone to metal-catalyzed oxidation (MCO) typical in processing and during storage of foods. New tools are needed for the detection of characteristic oxidation products especially from tryptophan and cysteine that often remain unrecognized when using the traditional methods of carbonyl formation monitoring. In this study, the oxidative changes in α-La were investigated through tryptic digestion and collection of 3 descriptive peptides fitted into a metal-catalyzed oxidation (Fenton reaction) model. The peptide samples were oxidized at +37 °C for 14 d and explored with liquid chromatography-quadrupole ion trap-mass spectrometer (LC-MS n ). The fractionated α-La peptides were valyl-glycyl-isoleucyl-asparaginyl-tyrosyl-tryptophyl-leucyl-alanyl-histidyl-lysine (VGINYWLAHK), leucyl-aspartyl-glutaminyl-tryptophyl-leucyl-cysteinyl-glutamyl-lysine (LDQWLCEK), and tryptophyl +16 -leucyl-alanyl-histidyl-lysyl-alanyl-leucyl-cysteine (W +16 LAHKALC). Oxidation of several amino acids, such as cysteine, histidine, lysine, and tryptophan was observed. In the peptide LDQWLCEK, cysteine was rapidly trioxidized to sulfonic acid, followed by other amino acid side chains as secondary oxidation sites. Tryptophan oxidation was more pronounced in the peptides W +16 LAHKALC and VGINYWLAHK, and also formation of the harmful N-formylkynurenine was observed. As a conclusion, several stable and promising oxidation markers are proposed for α-La, which could be implemented in the evaluation of quality and safety of dairy protein-containing products. © 2017 Institute of Food Technologists®.

Two Reactive Zones within Riverbank Aquifers Impact the Accumulation of Arsenic within Permeable Natural Reactive Barrier

NASA Astrophysics Data System (ADS)

Knappett, P.; Myers, K.; Jewell, K.; Berube, M.; Datta, S.; Hossain, A.; Hosain, A.; Lipsi, M.; Ahmed, K. M.

2017-12-01

River stage fluctuations drives river water, rich oxidants, into riverbanks aquifers. When these aquifers are rich in dissolved iron (Fe), iron oxides (FeOOH) precipitate, creating a reactive surface upon which toxic elements such as arsenic (As) may sorb. These Permeable Natural Reactive Barriers (PNRBs) have been studied on the Meghna River. The lack of understanding of what controls their formation and fate could result in dangerous consequences. Pumping of riverbank aquifers for irrigation could re-mobilize toxic concentrations of As into drinking water aquifers. It is important to understand the hydrological, geochemical and biological processes controlling the properties of PNRBs. To this end, monitoring wells and drive-point piezometers were installed orthogonal to the Meghna River in Bangladesh. The dimensions of the shallow aquifer was mapped with Electrical Resistivity Tomography (ERT). The monitoring wells and a river gage were instrumented with pressure transducers to record water level fluctuations. Groundwater flows towards the river for most of the year but reverses under the influence of local irrigation pumping in the late dry season and rapidly rising river stage in the early monsoon. Semi-diurnal tides in the dry season have an amplitude of 80 cm. Declining concentrations of conservative dissolved ions towards the river indicated a zone of dilution from river water extending up to 50 m from the river's dry season edge. Dissolved As was produced as groundwater passed through this dilution zone until the final 20 m where As was abruptly removed from solution. This location coincided with a PNRB with enriched solid-phase Fe and Mn within the upper 3 m of sediment. 16S bacterial community DNA was sequenced from the wells and drive-point piezometers to map the distribution of Fe and As reducers and oxidizers. The richest overall biodiversity was found within the PNRB zone. It contained the most oxidizing and reducing species. This evidence suggests that transient river levels drive mixing between oxidizing and reducing agents in Hyporheic Zones (HZs). When the shallow aquifers are rich in dissolved concentrations of Fe and As, this mixing results in the accumulation of solid-phase Fe and As. This is likely a general process affecting other oxide-forming metals and toxic elements they bind.

Ozonation of the food dye Brilliant Blue in aqueous medium: monitoring and characterization of products by direct infusion electrospray ionization coupled to high-resolution mass spectrometry.

PubMed

da Silva, Júlio César Cardoso; Bispo, Glayson Leonardo; Pavanelli, Sérgio Pinton; Afonso, Robson José de Cássia Franco; Augusti, Rodinei

2012-06-15

Dyes have been widely used to accentuate or to provide different colors to foods. However, the high concentrations of dyes in effluents from the food industries can cause serious and unpredictable damages to aquatic life in general. Furthermore, since conventional biological treatments have been shown to be ineffective, the use of advanced oxidation processes to promote the depletion of such dyes in water bodies has turned out to be mandatory. The degradation of the food dye Brilliant Blue by ozone in aqueous solution is reported herein. The overall process was monitored in real time by using direct infusion electrospray ionization high-resolution mass spectrometry in the negative ion mode, ESI(-)-HRMS. Preliminary results (visual inspection and UV-vis spectra) showed the high efficiency of ozonation in causing the decoloration of an aqueous solution of the dye whereas TOC (total organic carbon) measurements revealed that such an oxidation process was unable to promote its complete mineralization. ESI(-)-HRMS data showed that the substrate consumption occurred concomitantly with the appearance of four by-products, all of them produced by an initial attack of hydroxyl radicals (generated via the decomposition of ozone) on the two imino moieties of the dye molecule. Structures were proposed for all the by-products based mainly on the high-resolution mass measurements and on the characteristic reactivity of typical functional groups towards hydroxyl radicals. An unprecedented degradation route of Brilliant Blue by ozone in aqueous solution could thus be proposed. A greater ecotoxicity against Artemia salina was observed for the by-products than for the original dye. This indicates that the identification of by-products arising from oxidation treatments is of primary importance since such compounds can be more hazardous than the precursor itself. Copyright © 2012 John Wiley & Sons, Ltd.

A review on chemiresistive room temperature gas sensors based on metal oxide nanostructures, graphene and 2D transition metal dichalcogenides.

PubMed

Joshi, Nirav; Hayasaka, Takeshi; Liu, Yumeng; Liu, Huiliang; Oliveira, Osvaldo N; Lin, Liwei

2018-03-10

Room-temperature (RT) gas sensing is desirable for battery-powered or self-powered instrumentation that can monitor emissions associated with pollution and industrial processes. This review (with 171 references) discusses recent advances in three types of porous nanostructures that have shown remarkable potential for RT gas sensing. The first group comprises hierarchical oxide nanostructures (mainly oxides of Sn, Ni, Zn, W, In, La, Fe, Co). The second group comprises graphene and its derivatives (graphene, graphene oxides, reduced graphene oxides, and their composites with metal oxides and noble metals). The third group comprises 2D transition metal dichalcogenides (mainly sulfides of Mo, W, Sn, Ni, also in combination with metal oxides). They all have been found to enable RT sensing of gases such as NOx, NH 3 , H 2 , SO 2 , CO, and of vapors such as of acetone, formaldehyde or methanol. Attractive features also include high selectivity and sensitivity, long-term stability and affordable costs. Strengths and limitations of these materials are highlighted, and prospects with respect to the development of new materials to overcome existing limitations are discussed. Graphical Abstract The review summarizes the most significant progresses related to room temperature gas sensing by using hierarchical oxide nanostructures, graphene and its derivatives and 2D transition metal dichalcogenides, highlighting the peculiar gas sensing behavior with enhanced selectivity, sensitivity and long-term stability.

Novel hand-held device for exhaled nitric oxide-analysis in research and clinical applications.

PubMed

Hemmingsson, Tryggve; Linnarsson, Dag; Gambert, Rudolf

2004-12-01

Changes in expired nitric oxide (NO) occur in airway inflammation and have proved to be important in the monitoring of inflammatory disease processes such as asthma. We set out to develop a novel hand-held NO-analyzer with a performance comparable to the present more costly and complex chemiluminescence instruments. The new device is based on a specially designed electrochemical sensor, where we have developed a novel sampling and analysis technology, compensating for the relatively slow response properties of the electrochemical sensor technique. A Lowest Detection Limit in NO-analysis from reference gas tests of less than 3 ppb and a response time of 15 seconds together with an average precision in human breath measurements of 1.4 ppb were obtained. We also show an agreement with the existing 'gold standard' FENO measurement technique, within 0.5 ppb in a group of 19 subjects together with a high linearity and accuracy compared to reference gases. The new analyzer enables affordable monitoring of inflammatory airway diseases in research and routine clinical practice.

Distributed Optical Fiber Sensors with Ultrafast Laser Enhanced Rayleigh Backscattering Profiles for Real-Time Monitoring of Solid Oxide Fuel Cell Operations.

PubMed

Yan, Aidong; Huang, Sheng; Li, Shuo; Chen, Rongzhang; Ohodnicki, Paul; Buric, Michael; Lee, Shiwoo; Li, Ming-Jun; Chen, Kevin P

2017-08-24

This paper reports a technique to enhance the magnitude and high-temperature stability of Rayleigh back-scattering signals in silica fibers for distributed sensing applications. With femtosecond laser radiation, more than 40-dB enhancement of Rayleigh backscattering signal was generated in silica fibers using 300-nJ laser pulses at 250 kHz repetition rate. The laser-induced Rayleigh scattering defects were found to be stable from the room temperature to 800 °C in hydrogen gas. The Rayleigh scatter at high temperatures was correlated to the formation and modification of nanogratings in the fiber core. Using optical fibers with enhanced Rayleigh backscattering profiles as distributed temperature sensors, we demonstrated real-time monitoring of solid oxide fuel cell (SOFC) operations with 5-mm spatial resolution at 800 °C. Information gathered by these fiber sensor tools can be used to verify simulation results or operated in a process-control system to improve the operational efficiency and longevity of SOFC-based energy generation systems.

40 CFR 63.6000 - How do I conduct tests and procedures for puncture sealant application affected sources?

Code of Federal Regulations, 2011 CFR

2011-07-01

... oxidizer, monitor the firebox secondary chamber temperature. (ii) If you use a carbon adsorber, monitor the total regeneration stream mass or volumetric flow for each regeneration cycle, and the carbon bed... control device used other than a thermal oxidizer or a regenerative carbon adsorber, install and operate a...

40 CFR 63.6000 - How do I conduct tests and procedures for puncture sealant application affected sources?

Code of Federal Regulations, 2010 CFR

2010-07-01

... oxidizer, monitor the firebox secondary chamber temperature. (ii) If you use a carbon adsorber, monitor the total regeneration stream mass or volumetric flow for each regeneration cycle, and the carbon bed... control device used other than a thermal oxidizer or a regenerative carbon adsorber, install and operate a...

40 CFR 63.6000 - How do I conduct tests and procedures for puncture sealant application affected sources?

Code of Federal Regulations, 2012 CFR

2012-07-01

... thermal oxidizer, monitor the firebox secondary chamber temperature. (ii) If you use a carbon adsorber, monitor the total regeneration stream mass or volumetric flow for each regeneration cycle, and the carbon...) For each control device used other than a thermal oxidizer or a regenerative carbon adsorber, install...

40 CFR 63.6000 - How do I conduct tests and procedures for puncture sealant application affected sources?

Code of Federal Regulations, 2014 CFR

2014-07-01

... thermal oxidizer, monitor the firebox secondary chamber temperature. (ii) If you use a carbon adsorber, monitor the total regeneration stream mass or volumetric flow for each regeneration cycle, and the carbon...) For each control device used other than a thermal oxidizer or a regenerative carbon adsorber, install...

40 CFR 63.6000 - How do I conduct tests and procedures for puncture sealant application affected sources?

Code of Federal Regulations, 2013 CFR

2013-07-01

... thermal oxidizer, monitor the firebox secondary chamber temperature. (ii) If you use a carbon adsorber, monitor the total regeneration stream mass or volumetric flow for each regeneration cycle, and the carbon...) For each control device used other than a thermal oxidizer or a regenerative carbon adsorber, install...

40 CFR 63.4768 - What are the requirements for continuous parameter monitoring system installation, operation, and...

Code of Federal Regulations, 2011 CFR

2011-07-01

... requirements in paragraphs (c)(1) through (3) of this section: (1) For a thermal oxidizer, install a gas... firebox before any substantial heat exchange occurs. (2) For a catalytic oxidizer, you must install a gas temperature monitor in the gas stream immediately before the catalyst bed, and if you established operating...

40 CFR 63.4768 - What are the requirements for continuous parameter monitoring system installation, operation, and...

Code of Federal Regulations, 2010 CFR

2010-07-01

... requirements in paragraphs (c)(1) through (3) of this section: (1) For a thermal oxidizer, install a gas... firebox before any substantial heat exchange occurs. (2) For a catalytic oxidizer, you must install a gas temperature monitor in the gas stream immediately before the catalyst bed, and if you established operating...

40 CFR 63.4168 - What are the requirements for continuous parameter monitoring system installation, operation, and...

Code of Federal Regulations, 2010 CFR

2010-07-01

... paragraphs (a) and (c)(1) through (3) of this section: (1) For a thermal oxidizer, install a gas temperature... any substantial heat exchange occurs. (2) For a catalytic oxidizer, install a gas temperature monitor in the gas stream immediately before the catalyst bed, and if you establish operating limits...

40 CFR 63.4168 - What are the requirements for continuous parameter monitoring system installation, operation, and...

Code of Federal Regulations, 2011 CFR

2011-07-01

... paragraphs (a) and (c)(1) through (3) of this section: (1) For a thermal oxidizer, install a gas temperature... any substantial heat exchange occurs. (2) For a catalytic oxidizer, install a gas temperature monitor in the gas stream immediately before the catalyst bed, and if you establish operating limits...

Oxidation kinetics of the combustible fraction of construction and demolition wastes.

PubMed

Chang, N B; Lin, K S; Sun, Y P; Wang, H P

2001-01-01

Proper disposal of construction and demolition wastes (CDW) has received wide attention recently due to significantly large quantities of waste streams collected from razed or retrofitted buildings in many metropolitan regions. Burning the combustible fractions of CDW (CCDW) and possibly recovering part of the heat content for economic uses could be valuable for energy conservation. This paper explores the oxidation kinetics of CCDW associated with its ash characterization. Kinetic parameters for the oxidation of CCDW were numerically calculated using thermal gravimetric analysis (TGA) and the resultant rate equations were therefore developed for illustrating the oxidation processes of CCDW simultaneously. Based on three designated heating rates, each of the oxidation processes can be featured distinctively with five different stages according to the rate of weight change at the temperature between 300 K and 923 K. In addition, Fourier transform infrared (FTIR) spectroscopy was employed, associated with a lab-scale fixed-bed incinerator for monitoring the composition of flue gas. Carbon dioxide (CO2) was found as a major component in the flue gas. The fuel analysis also included an ash composition analysis via the use of X-ray powder diffraction (XRD), atomic absorption (AA) spectroscopy, inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDX). The ash streams were identified as nonhazardous materials based on the toxicity characteristic leaching procedure (TCLP). Overall, the scientific findings gained in this study will be helpful for supporting a sound engineering design of real-world CCDW incineration systems.

Chromium cycling in soils and water: links, gaps, and methods.

PubMed

Bartlett, R J

1991-05-01

The major links in the cycling of chromium in soils and in natural waters are between chromium(III) and chromium (VI). Between the larger links are lesser links involving processes of mobilization and oxidation of CrIII and reduction of CrVI. The gaps are mainly in our understanding of the factors that control these processes. If soluble CrIII is added to an "average" soil, a portion of it will become immediately oxidized by manganese oxides to CrVI. The rest of the CrIII may remain reduced for long periods of time, even in the presence of electron-accepting manganese oxides. However, this less available CrIII can be mobilized by low molecular weight organic complexers and then oxidized where redox conditions are optimal. Usually part of any CrVI added to a soil or sediment will be reduced instantly, especially under acid conditions. On the other hand, high concentrations of polluting CrVI may quickly exhaust the readily available reducing power of the matrix material and excess CrVI, the thermodynamically stable form in air, may persist for years in soils or lagoons without reduction. Cleanup of chromium pollution must involve the surrounding of both CrIII and CrVI with excesses of slowly available reducing substances and sealing them permanently from inputs of atmospheric oxygen. Monitoring the effectiveness of the measures is mandatory, but fortunately the chemical testing for CrVI in soil and water is simple and problem free compared with most colorimetric determinations.

Spectroscopic methods of process monitoring for safeguards of used nuclear fuel separations

NASA Astrophysics Data System (ADS)

Warburton, Jamie Lee

To support the demonstration of a more proliferation-resistant nuclear fuel processing plant, techniques and instrumentation to allow the real-time, online determination of special nuclear material concentrations in-process must be developed. An ideal materials accountability technique for proliferation resistance should provide nondestructive, realtime, on-line information of metal and ligand concentrations in separations streams without perturbing the process. UV-Visible spectroscopy can be adapted for this precise purpose in solvent extraction-based separations. The primary goal of this project is to understand fundamental URanium EXtraction (UREX) and Plutonium-URanium EXtraction (PUREX) reprocessing chemistry and corresponding UV-Visible spectroscopy for application in process monitoring for safeguards. By evaluating the impact of process conditions, such as acid concentration, metal concentration and flow rate, on the sensitivity of the UV-Visible detection system, the process-monitoring concept is developed from an advanced application of fundamental spectroscopy. Systematic benchtop-scale studies investigated the system relevant to UREX or PUREX type reprocessing systems, encompassing 0.01-1.26 M U and 0.01-8 M HNO3. A laboratory-scale TRansUranic Extraction (TRUEX) demonstration was performed and used both to analyze for potential online monitoring opportunities in the TRUEX process, and to provide the foundation for building and demonstrating a laboratory-scale UREX demonstration. The secondary goal of the project is to simulate a diversion scenario in UREX and successfully detect changes in metal concentration and solution chemistry in a counter current contactor system with a UV-Visible spectroscopic process monitor. UREX uses the same basic solvent extraction flowsheet as PUREX, but has a lower acid concentration throughout and adds acetohydroxamic acid (AHA) as a complexant/reductant to the feed solution to prevent the extraction of Pu. By examining UV-Visible spectra gathered in real time, the objective is to detect the conversion from the UREX process, which does not separate Pu, to the PUREX process, which yields a purified Pu product. The change in process chemistry can be detected in the feed solution, aqueous product or in the raffinate stream by identifying the acid concentration, metal distribution and the presence or absence of AHA. A fiber optic dip probe for UV-Visible spectroscopy was integrated into a bank of three counter-current centrifugal contactors to demonstrate the online process monitoring concept. Nd, Fe and Zr were added to the uranyl nitrate system to explore spectroscopic interferences and identify additional species as candidates for online monitoring. This milestone is a demonstration of the potential of this technique, which lies in the ability to simultaneously and directly monitor the chemical process conditions in a reprocessing plant, providing inspectors with another tool to detect nuclear material diversion attempts. Lastly, dry processing of used nuclear fuel is often used as a head-end step before solvent extraction-based separations such as UREX or TRUEX. A non-aqueous process, used fuel treatment by dry processing generally includes chopping of used fuel rods followed by repeated oxidation-reduction cycles and physical separation of the used fuel from the cladding. Thus, dry processing techniques are investigated and opportunities for online monitoring are proposed for continuation of this work in future studies.

A Continuous Flow System for the Measurement of Ambient Nitrogen Oxides [NO + NO2] Using Rhodamine B Hydrazide as a Chemosensor.

PubMed

Malingappa, Pandurangappa; Yarradoddappa, Venkataramanappa

2014-01-01

A new chemosensor has been used to monitor atmospheric nitrogen oxides [NO + NO2] at parts per billion (ppb) level. It is based on the catalytic reaction of nitrogen oxides with rhodamine B hydrazide (RBH) to produce a colored compound through the hydrolysis of the amide bond of the molecule. A simple colorimeter has been used to monitor atmospheric nitrogen dioxide at ppb level. The air samples were purged through a sampling cuvette containing RBH solution using peristaltic pump. The proposed method has been successfully applied to monitor the ambient nitrogen dioxide levels at traffic junction points within the city limits and the results obtained are compared with the standard Griess-Ilosvay method.

Linoleic Acid-Induced Ultra-Weak Photon Emission from Chlamydomonas reinhardtii as a Tool for Monitoring of Lipid Peroxidation in the Cell Membranes

PubMed Central

Prasad, Ankush; Pospíšil, Pavel

2011-01-01

Reactive oxygen species formed as a response to various abiotic and biotic stresses cause an oxidative damage of cellular component such are lipids, proteins and nucleic acids. Lipid peroxidation is considered as one of the major processes responsible for the oxidative damage of the polyunsaturated fatty acid in the cell membranes. Various methods such as a loss of polyunsaturated fatty acids, amount of the primary and the secondary products are used to monitor the level of lipid peroxidation. To investigate the use of ultra-weak photon emission as a non-invasive tool for monitoring of lipid peroxidation, the involvement of lipid peroxidation in ultra-weak photon emission was studied in the unicellular green alga Chlamydomonas reinhardtii. Lipid peroxidation initiated by addition of exogenous linoleic acid to the cells was monitored by ultra-weak photon emission measured with the employment of highly sensitive charged couple device camera and photomultiplier tube. It was found that the addition of linoleic acid to the cells significantly increased the ultra-weak photon emission that correlates with the accumulation of lipid peroxidation product as measured using thiobarbituric acid assay. Scavenging of hydroxyl radical by mannitol, inhibition of intrinsic lipoxygenase by catechol and removal of molecular oxygen considerably suppressed ultra-weak photon emission measured after the addition of linoleic acid. The photon emission dominated at the red region of the spectrum with emission maximum at 680 nm. These observations reveal that the oxidation of linoleic acid by hydroxyl radical and intrinsic lipoxygenase results in the ultra-weak photon emission. Electronically excited species such as excited triplet carbonyls are the likely candidates for the primary excited species formed during the lipid peroxidation, whereas chlorophylls are the final emitters of photons. We propose here that the ultra-weak photon emission can be used as a non-invasive tool for the detection of lipid peroxidation in the cell membranes. PMID:21799835

Near-infrared diode laser hydrogen fluoride monitor for dielectric etch

NASA Astrophysics Data System (ADS)

Xu, Ning; Pirkle, David R.; Jeffries, Jay B.; McMillin, Brian; Hanson, Ronald K.

2004-11-01

A hydrogen fluoride (HF) monitor, using a tunable diode laser, is designed and used to detect the etch endpoints for dielectric film etching in a commercial plasma reactor. The reactor plasma contains HF, a reaction product of feedstock gas CF4 and the hydrogen-containing films (photoresist, SiOCH) on the substrate. A near-infrared diode laser is used to scan the P(3) transition in the first overtone of HF near 1.31 μm to monitor changes in the level of HF concentration in the plasma. Using 200 ms averaging and a signal modulation technique, we estimate a minimum detectable HF absorbance of 6×10-5 in the etch plasma, corresponding to an HF partial pressure of 0.03 mTorr. The sensor could indicate, in situ, the SiOCH over tetraethoxysilane oxide (TEOS) trench endpoint, which was not readily discerned by optical emission. These measurements demonstrate the feasibility of a real-time diode laser-based sensor for etch endpoint monitoring and a potential for process control.

The measurement of Protein Synthesis for Assessing Proteostasis in Studies of Slowed Aging

PubMed Central

Miller, Benjamin F.; Drake, Joshua C.; Naylor, Bradley; Price, John C.; Hamilton, Karyn L.

2014-01-01

Slowing the aging process can reduce the risk for multiple chronic diseases simultaneously. It is increasingly recognized that maintaining protein homeostasis (or proteostasis) is important for slowing the aging process. Since proteostasis is a dynamic process, monitoring it is not a simple task and requires use of appropriate methods. This review will introduce methods to assess protein and DNA synthesis using deuterium oxide (D2O), and how protein and DNA synthesis outcomes provide insight into proteostatic mechanisms. Finally, we provide a discussion on how these assessments of protein and DNA synthesis are “mechanistic” investigations and provide an appropriate framework for the further development of slowed aging treatments. PMID:25283966

A new process and equipment for waste minimization: Conversion of NO(x) scrubber liquor to fertilizer

NASA Technical Reports Server (NTRS)

Parrish, Clyde F.; Barile, Ronald G.; Gamble, Paul H.; Lueck, Dale E.; Young, Rebecca C.

1995-01-01

A new emissions control system for the oxidizer scrubbers that eliminates the current oxidizer liquor waste and lowers the NO(x) emissions is described. Since fueling and deservicing spacecraft constitute the primary operations in which environmental emissions occur, this will eliminate the second largest waste stream at KSC. This effort is in accord with Executive Order No. 12856 (Federal Compliance with Right-to-Know Laws and Pollution Prevention Requirements, data 6 Aug. 1993) and Executive Order No. 12873 (Federal Acquisition, Recycling, and Waste Prevention, dated 20 Oct. 1993). A recent study found that the efficiencies of the oxidizer scrubbers during normal operations ranged from 70 percent to 99 percent. The new scrubber liquor starts with 1% hydrogen peroxide at a pH of 7 and the process control system adds hydrogen peroxide and potassium hydroxide to the scrubber liquor to maintain those initial conditions. The result is the formation of a solution of potassium nitrate, which is sold as a fertilizer. This report describes the equipment and procedures used to monitor and control the conversion of the scrubber liquor to fertilizer, while reducing the scrubber emissions.

Insights into electrode/electrolyte interfacial processes and the effect of nanostructured cobalt oxides loading on graphene-based hybrids by scanning electrochemical microscopy

NASA Astrophysics Data System (ADS)

Gupta, Sanju; Carrizosa, Sara B.

2016-12-01

Nanostructured cobalt oxide polymorphs (CoO and Co3O4) deposited via electrodeposition allowed optimal loading on supercapacitive graphene nanosheets producing a set of graphene-based hybrids namely, CoO/GO, CoO/ErGO, Co3O4/GO, Co3O4/rGO, and Co3O4/ErGO, as pseudocapacitive electrochemical electrodes. We gained fundamental insights into the complex physicochemical interfacial processes at electrode surfaces and electrode/electrolyte (or solid/liquid) interfaces by scanning electrochemical microscopy operating in the feedback probe approach and imaging modes while monitoring and mapping the redox probe (re)activity behavior. We determined the various experimental descriptors including diffusion coefficient, electron transfer rate, and electroactive site distribution on electrodes. We emphasize the interplay of (1) heterogeneous basal and edge plane active sites, (2) graphene surface functional moieties (conducting/semiconducting), and (3) crystalline spinel cobalt oxides (semiconducting/insulating) coated graphene, reinforcing the available electron density of states in the vicinity of the Fermi level contributing to higher electroactivity, faster interfacial diffusion, and shorter distances for electron transfer, facilitated through molecular and chemical bridges obtained by electrodeposition as compared with the physical deposition.

Uranium Isotope Fractionation during Oxidation of Dissolved U(iv) and Synthetic Solid UO2

NASA Astrophysics Data System (ADS)

Wang, X.; Johnson, T. M.; Lundstrom, C. C.

2013-12-01

U isotopes (238U/235U) show promise as a tool for environmental monitoring of U contamination as well as a proxy for paleo-redox conditions. However, the isotopic fractionation mechanisms of U are still poorly understood. In groundwater systems, U(VI), a mobile contaminant, can be reduced to immobile U(IV) and thus remediated. Previous work shows that 238U/235U of the remaining U(VI) changes with the extent of reduction. Therefore, U(VI) isotope composition in groundwater can potentially be used to detect and perhaps quantify the extent of reduction. However, knowing if isotopic fractionation occurs during U(IV) oxidation is equally important. First, the reduced U(IV) (either solid or as dissolved organic complexes) potentially can be reoxidized to U(VI). If isotope fractionation occurs during oxidation, it would complicate the use of U isotope composition as a monitoring technique. Further, in natural weathering processes, U(IV) minerals are oxidized to form dissolved U(VI), which is carried to rivers and eventually to the ocean and deposited in marine sediments. The weathering cycle is thus sensitive to redox conditions, meaning the sedimentary U isotope record may serve as a paleoredox indicator, provided U isotope fractionation during oxidation and reduction are well known. We conducted experiments oxidizing 2 different U(IV) species by O2 and measuring isotopic fractionation factors. In one experiment, dissolved U(IV) in 0.1 N HCl (pH 1) was oxidized by entrained air. As oxidation proceeds at pH 1, the remaining dissolved U(IV) becomes progressively enriched in 238U in a linear trend, while the product U(VI) paralleled, but was offset to 1.0‰ lighter in 238U/235U. This linear progression of both remaining reactant and product suggests equilibrium fractionation during oxidation of dissolved U(IV) by O2. A second experiment oxidized synthetic, solid UO2 (in 20 mM NaHCO3, pH 7) with entrained air. The oxidative fractionation is very weak in this case with product U(VI) ~0.1‰ heavier than the remaining UO2. We attribute the lack of strong fractionation during oxidation of solid UO2 to a 'rind effect', where the surface layer must be completely oxidized before the next layer is exposed to oxidant. Hence, nearly complete, congruent conversion of each layer of U(IV) to U(VI) results in minimal isotope fractionation. A small amount of transient fractionation probably occurs initially, but this is quickly negated as the surface becomes isotopically fractionated. Interestingly, our measured ~0.1‰ U isotope fractionation during oxidation of solid U(IV) agrees with the natural observation that 238U/235U ratios in river water (mainly U(VI)) are ~0.1‰ greater than those in fresh continental rocks (primarily U(IV) minerals). Application of these results to natural settings should be done with caution, however. Oxidation of natural uraninite in continental rocks is a much slower process. If the U(VI) product and the U(IV) reactant remain in contact for long periods of time (e.g., months), they may evolve toward isotopic equilibrium. Measurements of 238U/235U in various natural weathering environments should be undertaken to examine this idea.

Remote sensing of methane and nitrous oxide fluxes from waste incineration.

PubMed

Gålfalk, Magnus; Bastviken, David

2018-05-01

Incomplete combustion processes lead to the formation of many gaseous byproducts that can be challenging to monitor in flue gas released via chimneys. This study presents ground-based remote sensing approaches to make greenhouse gas (GHG) flux measurements of methane (CH 4 ) and nitrous oxide (N 2 O) from a waste incineration chimney at distances of 150-200 m. The study found emission of N 2 O (corresponding to 30-40 t yr -1 ), which is a consequence of adding the reduction agent urea to decrease NO X emissions due to NO X regulation; a procedure that instead increases N 2 O emissions (which is approximately 300 times more potent as a GHG than CO 2 on a 100-year time scale). CH 4 emissions of 7-11 t yr -1 was also detected from the studied chimney despite the usage of a high incineration temperature. For this particular plant, local knowledge is high and emission estimates at corresponding levels have been reported previously. However, emissions of CH 4 are often not included in GHG emission inventories for waste incineration. This study highlights the importance of monitoring combustion processes, and shows the possibility of surveying CH 4 and N 2 O emissions from waste incineration at distances of several hundred meters. Copyright © 2018 Elsevier Ltd. All rights reserved.

Evolution of microbial dynamics during the maturation phase of the composting of different types of waste.

PubMed

Villar, Iria; Alves, David; Garrido, Josefina; Mato, Salustiano

2016-08-01

During composting, facilities usually exert greater control over the bio-oxidative phase of the process, which uses a specific technology and generally has a fixed duration. After this phase, the material is deposited to mature, with less monitoring during the maturation phase. While there has been considerable study of biological parameters during the thermophilic phase, there is less research on the stabilization and maturation phase. This study evaluates the effects of the type of starting material on the evolution of microbial dynamics during the maturation phase of composting. Three waste types were used: sludge from the fish processing industry, municipal sewage sludge and pig manure, each independently mixed with shredded pine wood as bulking agent. The composting system for each waste type comprised a static reactor with capacity of 600L for the bio-oxidative phase followed by stabilization and maturation phase in triplicate 200L boxes for 112days. Phospholipid fatty acids, enzyme activities and physico-chemical parameters were measured throughout the maturation phase. The evolution of the total microbial biomass, Gram + bacteria, Gram - bacteria, fungi and enzymatic activities (β-glucosidase, cellulase, protease, acid and alkaline phosphatase) depended significantly on the waste type (p<0.001). The predominant microbial community for each waste type remained present throughout the maturation process, indicating that the waste type determines the microorganisms that are able to develop at this stage. While fungi predominated during fish sludge maturation, manure and municipal sludge were characterized by a greater proportion of bacteria. Both the structure of the microbial community and enzymatic activities provided important information for monitoring the composting process. More attention should be paid to the maturation phase in order to optimize composting. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

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

PubMed

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

2013-10-23

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

How plasma induced oxidation, oxygenation, and de-oxygenation influences viability of skin cells

NASA Astrophysics Data System (ADS)

Oh, Jun-Seok; Strudwick, Xanthe; Short, Robert D.; Ogawa, Kotaro; Hatta, Akimitsu; Furuta, Hiroshi; Gaur, Nishtha; Hong, Sung-Ha; Cowin, Allison J.; Fukuhara, Hideo; Inoue, Keiji; Ito, Masafumi; Charles, Christine; Boswell, Roderick W.; Bradley, James W.; Graves, David B.; Szili, Endre J.

2016-11-01

The effect of oxidation, oxygenation, and de-oxygenation arising from He gas jet and He plasma jet treatments on the viability of skin cells cultured in vitro has been investigated. He gas jet treatment de-oxygenated cell culture medium in a process referred to as "sparging." He plasma jet treatments oxidized, as well as oxygenated or de-oxygenated cell culture medium depending on the dissolved oxygen concentration at the time of treatment. He gas and plasma jets were shown to have beneficial or deleterious effects on skin cells depending on the concentration of dissolved oxygen and other oxidative molecules at the time of treatment. Different combinations of treatments with He gas and plasma jets can be used to modulate the concentrations of dissolved oxygen and other oxidative molecules to influence cell viability. This study highlights the importance of a priori knowledge of the concentration of dissolved oxygen at the time of plasma jet treatment, given the potential for significant impact on the biological or medical outcome. Monitoring and controlling the dynamic changes in dissolved oxygen is essential in order to develop effective strategies for the use of cold atmospheric plasma jets in biology and medicine.

Aging: a portrait from gene expression profile in blood cells.

PubMed

Calabria, Elisa; Mazza, Emilia Maria Cristina; Dyar, Kenneth Allen; Pogliaghi, Silvia; Bruseghini, Paolo; Morandi, Carlo; Salvagno, Gian Luca; Gelati, Matteo; Guidi, Gian Cesare; Bicciato, Silvio; Schiaffino, Stefano; Schena, Federico; Capelli, Carlo

2016-08-01

The availability of reliable biomarkers of aging is important not only to monitor the effect of interventions and predict the timing of pathologies associated with aging but also to understand the mechanisms and devise appropriate countermeasures. Blood cells provide an easily available tissue and gene expression profiles from whole blood samples appear to mirror disease states and some aspects of the aging process itself. We report here a microarray analysis of whole blood samples from two cohorts of healthy adult and elderly subjects, aged 43±3 and 68±4 years, respectively, to monitor gene expression changes in the initial phase of the senescence process. A number of significant changes were found in the elderly compared to the adult group, including decreased levels of transcripts coding for components of the mitochondrial respiratory chain, which correlate with a parallel decline in the maximum rate of oxygen consumption (VO2max), as monitored in the same subjects. In addition, blood cells show age-related changes in the expression of several markers of immunosenescence, inflammation and oxidative stress. These findings support the notion that the immune system has a major role in tissue homeostasis and repair, which appears to be impaired since early stages of the aging process.

Direct technique for monitoring lipid oxidation in water-in-oil emulsions based on micro-calorimetry.

PubMed

Dridi, Wafa; Toutain, Jean; Sommier, Alain; Essafi, Wafa; Leal-Calderon, Fernando; Cansell, Maud

2017-09-01

An experimental device based on the measurement of the heat flux dissipated during chemical reactions, previously validated for monitoring lipid oxidation in plant oils, was extended to follow lipid oxidation in water-in-oil emulsions. Firstly, validation of the approach was performed by correlating conjugated diene concentrations measured by spectrophotometry and the heat flux dissipated by oxidation reactions and measured directly in water-in-oil emulsions, in isothermal conditions at 60°C. Secondly, several emulsions based on plant oils differing in their n-3 fatty acid content were compared. The oxidability parameter derived from the enthalpy curves reflected the α-linolenic acid proportion in the oils. On the whole, the micro-calorimetry technique provides a sensitive method to assess lipid oxidation in water-in-oil emulsions without requiring any phase extraction. Copyright © 2017 Elsevier Ltd. All rights reserved.

Detection of defects in laser welding of AZ31B magnesium alloy in zero-gap lap joint configuration by a real-time spectroscopic analysis

NASA Astrophysics Data System (ADS)

Harooni, Masoud; Carlson, Blair; Kovacevic, Radovan

2014-05-01

The effect of surface oxide layer existing at the lap-joint faying surface of magnesium sheets is investigated on the keyhole dynamics of the weld pool and weld bead qualities. It is observed that by removing the oxide layer from the faying surface of the lap joint, a high quality weld can be achieved in the laser welding process. However, the presence of an oxide layer deteriorates the quality of the weld by forming pores at the interface of the two overlapped sheets. The purpose of this paper is to identify the correlation between the integrity of the weld and the interaction between the laser and material. A spectroscopy sensor was applied to detect the spectra emitted from a plasma plume during the laser welding of AZ31B magnesium alloy in a zero-gap lap joint configuration. The electron temperature was calculated by applying a Boltzmann plot method based on the detected spectra, and the correlation between the pore formation and the spectral signals was studied. The laser molten pool and the keyhole condition were monitored in real-time by a high speed charge-coupled device (CCD) camera. A green laser was used as an illumination source in order to detect the influence of the oxide layer on the dynamic behavior of the molten pool. Results revealed that the detected spectrum and weld defects had a meaningful correlation for real-time monitoring of the weld quality during laser welding of magnesium alloys.

Modelling and analysis of ozone concentration by artificial intelligent techniques for estimating air quality

NASA Astrophysics Data System (ADS)

Taylan, Osman

2017-02-01

High ozone concentration is an important cause of air pollution mainly due to its role in the greenhouse gas emission. Ozone is produced by photochemical processes which contain nitrogen oxides and volatile organic compounds in the lower atmospheric level. Therefore, monitoring and controlling the quality of air in the urban environment is very important due to the public health care. However, air quality prediction is a highly complex and non-linear process; usually several attributes have to be considered. Artificial intelligent (AI) techniques can be employed to monitor and evaluate the ozone concentration level. The aim of this study is to develop an Adaptive Neuro-Fuzzy inference approach (ANFIS) to determine the influence of peripheral factors on air quality and pollution which is an arising problem due to ozone level in Jeddah city. The concentration of ozone level was considered as a factor to predict the Air Quality (AQ) under the atmospheric conditions. Using Air Quality Standards of Saudi Arabia, ozone concentration level was modelled by employing certain factors such as; nitrogen oxide (NOx), atmospheric pressure, temperature, and relative humidity. Hence, an ANFIS model was developed to observe the ozone concentration level and the model performance was assessed by testing data obtained from the monitoring stations established by the General Authority of Meteorology and Environment Protection of Kingdom of Saudi Arabia. The outcomes of ANFIS model were re-assessed by fuzzy quality charts using quality specification and control limits based on US-EPA air quality standards. The results of present study show that the ANFIS model is a comprehensive approach for the estimation and assessment of ozone level and is a reliable approach to produce more genuine outcomes.

Hypergolic oxidizer and fuel scrubber emissions

NASA Technical Reports Server (NTRS)

Parrish, Clyde F.; Barile, Ronald G.; Curran, Dan; Hodge, Tim; Lueck, Dale E.; Young, Rebecca C.

1995-01-01

Hypergolic fuels and oxidizer are emitted to the environment during fueling and deservicing shuttle and other spacecraft. Such emissions are difficult to measure due to the intermittent purge flow and to the presence of suspended scrubber liquor. A new method for emissions monitoring was introduced in a previous paper. This paper is a summary of the results of a one-year study of shuttle launch pads and orbiter processing facilities (OPF's) which proved that emissions can be determined from field scrubbers without direct measurement of vent flow rate and hypergol concentration. This new approach is based on the scrubber efficiency, which was measured during normal operations, and on the accumulated weight of hypergol captured in the scrubber liquor, which is part of the routine monitoring data of scrubber liquors. To validate this concept, three qualification tests were performed, logs were prepared for each of 16 hypergol scrubbers at KSC, the efficiencies of KSC scrubbers were measured during normal operations, and an estimate of the annual emissions was made based on the efficiencies and the propellant buildup data. The results have confirmed that the emissions from the KSC scrubbers can be monitored by measuring the buildup of hypergol propellant in the liquor, and then using the appropriate efficiency to calculate the emissions. There was good agreement between the calculated emissions based on outlet concentration and flow rate, and the emissions calculated from the propellant buildup and efficiency. The efficiencies of 12 KSC scrubbers, measured under actual servicing operations and special test conditions, were assumed to be valid for all subsequent operations until a significant change in hardware occurred. An estimate of the total emissions from 16 scrubbers for three years showed that 0.3 kg/yr of fuel and 234 kg/yr of oxidizer were emitted.

Photochemical oxidant transport - Mesoscale lake breeze and synoptic-scale aspects

NASA Technical Reports Server (NTRS)

Lyons, W. A.; Cole, H. S.

1976-01-01

Data from routine ozone monitoring in southeastern Wisconsin and limited monitoring of the Milwaukee area by the Environmental Protection Agency are examined. Hourly averages as high as 30 pphm have been recorded in southeastern Wisconsin, and high readings have been reported in rural regions throughout the state. The observations indicate that photochemical oxidants and their nitrogen oxide and reactive hydrocarbon precursers advect from Chicago and northern Indiana into southeastern Wisconsin. There is evidence that synoptic-scale transport of photochemical oxidants occurs, allowing the pollution of entire anticyclones. These results cast doubt on the validity of the Air Quality Control Regions established by amendment to the Clean Air Act of 1970.

Oxidative Stress in Spinocerebellar Ataxia Type 7 Is Associated with Disease Severity.

PubMed

Torres-Ramos, Y; Montoya-Estrada, A; Cisneros, B; Tercero-Pérez, K; León-Reyes, G; Leyva-García, N; Hernández-Hernández, Oscar; Magaña, Jonathan J

2018-06-06

Spinocerebellar ataxia type 7 is a neurodegenerative inherited disease caused by a CAG expansion in the coding region of the ATXN7 gene, which results in the synthesis of polyglutamine-containing ataxin-7. Expression of mutant ataxin-7 disturbs different cell processes, including transcriptional regulation, protein conformation and clearance, autophagy, and glutamate transport; however, mechanisms underlying neurodegeneration in SCA7 are still unknown. Implication of oxidative stress in the pathogenesis of various neurodegenerative diseases, including polyglutamine disorders, has recently emerged. We perform a cross-sectional study to determine for the first time pheripheral levels of different oxidative stress markers in 29 SCA7 patients and 28 age- and sex-matched healthy subjects. Patients with SCA7 exhibit oxidative damage to lipids (high levels of lipid hydroperoxides and malondialdehyde) and proteins (elevated levels of advanced oxidation protein products and protein carbonyls). Furthermore, SCA7 patients showed enhanced activity of various anti-oxidant enzymes (glutathione reductase, glutathione peroxidase, and paraoxonase) as well as increased total anti-oxidant capacity, which suggest that activation of the antioxidant defense system might occur to counteract oxidant damage. Strikingly, we found positive correlation between some altered oxidative stress markers and disease severity, as determined by different clinical scales, with early-onset patients showing a more severe disturbance of the redox system than adult-onset patients. In summay, our results suggest that oxidative stress might contribute to SCA7 pathogenesis. Furthermore, oxidative stress biomarkers that were found relevant to SCA7 in this study could be useful to follow disease progression and monitor therapeutic intervention.

Spectral analysis of light emitted during the oxidation of lipids and proteins

NASA Astrophysics Data System (ADS)

Turrens, Julio F.; Robinson, Eric; Freeman, Scott; George, Benedict F., III

2003-05-01

Oxidative stress is associated with a variety of pathological processes of clinical relevance. Some of the intermediates generated during the chain reactions associated with oxidation of lipids and proteins are electronically excited and decay emitting photons, which may be detected with the help of sensitive photomultipliers. This technique has been used to monitor oxidative stress in a variety of scenarios including intact organs in vivo or in vitro, and simple models such as proteins and lipids exposed to oxidants. The main drawback of this technique is that the emission of light is extremely weak and it is subjected to substantial interference from spurious sources. In addition, the quantum efficiency of photomultipliers varies with wavelength making it even more difficult to collect reliable data using photomultipliers sensitive to relatively broad spectral ranges. In order to identify the peak emission wavelengths in the visible region, we exposed model systems (proteins, lipids and amino acids) to peroxynitrite and sources of hydroxyl and alcoxyl radicals, analyzing the emission of light with interference filters. The results indicate that the peak emission for most biological models occurs between 450 and 700 nm. The emission at higher wavelengths (lower energy levels) was observed mostly in the presence of less powerful oxidants such as tert-butyl hydroperoxide.

The impact of pre-oxidation with potassium permanganate on cyanobacterial organic matter removal by coagulation.

PubMed

Naceradska, Jana; Pivokonsky, Martin; Pivokonska, Lenka; Baresova, Magdalena; Henderson, Rita K; Zamyadi, Arash; Janda, Vaclav

2017-05-01

The study investigates the effect of permanganate pre-oxidation on the coagulation of peptides/proteins of Microcystis aeruginosa which comprise a major proportion of the organic matter during cyanobacterial bloom decay. Four different permanganate dosages (0.1, 0.2, 0.4 and 0.6 mg KMnO 4 mg -1 DOC) were applied prior to coagulation by ferric sulphate. Moreover, changes in sample characteristics, such as UV 254 , DOC content and molecular weight distribution, after pre-oxidation were monitored. The results showed that permanganate pre-oxidation led to a reduction in coagulant dose, increased organic matter removals by coagulation (by 5-12% depending on permanganate dose), microcystin removal (with reductions of 91-96%) and a shift of the optimum pH range from 4.3 to 6 without to 5.5-7.3 with pre-oxidation. Degradation of organic matter into inorganic carbon and adsorption of organic matter onto hydrous MnO 2 are suggested as the main processes responsible for coagulation improvement. Moreover, permanganate prevented the formation of Fe-peptide/protein complexes that inhibit coagulation at pH about 6.2 without pre-oxidation. The study showed that carefully optimized dosing of permanganate improves cyanobacterial peptide/protein removal, with the benefit of microcystin elimination. Copyright © 2017 Elsevier Ltd. All rights reserved.

Optical Detection of Ketoprofen by Its Electropolymerization on an Indium Tin Oxide-Coated Optical Fiber Probe.

PubMed

Bogdanowicz, Robert; Niedziałkowski, Paweł; Sobaszek, Michał; Burnat, Dariusz; Białobrzeska, Wioleta; Cebula, Zofia; Sezemsky, Petr; Koba, Marcin; Stranak, Vitezslav; Ossowski, Tadeusz; Śmietana, Mateusz

2018-04-27

In this work an application of optical fiber sensors for real-time optical monitoring of electrochemical deposition of ketoprofen during its anodic oxidation is discussed. The sensors were fabricated by reactive magnetron sputtering of indium tin oxide (ITO) on a 2.5 cm-long core of polymer-clad silica fibers. ITO tuned in optical properties and thickness allows for achieving a lossy-mode resonance (LMR) phenomenon and it can be simultaneously applied as an electrode in an electrochemical setup. The ITO-LMR electrode allows for optical monitoring of changes occurring at the electrode during electrochemical processing. The studies have shown that the ITO-LMR sensor’s spectral response strongly depends on electrochemical modification of its surface by ketoprofen. The effect can be applied for real-time detection of ketoprofen. The obtained sensitivities reached over 1400 nm/M (nm·mg −1 ·L) and 16,400 a.u./M (a.u.·mg −1 ·L) for resonance wavelength and transmission shifts, respectively. The proposed method is a valuable alternative for the analysis of ketoprofen within the concentration range of 0.25⁻250 μg mL −1 , and allows for its determination at therapeutic and toxic levels. The proposed novel sensing approach provides a promising strategy for both optical and electrochemical detection of electrochemical modifications of ITO or its surface by various compounds.

Increased breath ethane levels in medicated patients with schizophrenia and bipolar disorder are unrelated to erythrocyte omega-3 fatty acid abundance.

PubMed

Ross, Brian M; Maxwell, Ross; Glen, Iain

2011-03-30

Oxidative stress has been reported to be elevated in mental illness. Preliminary evidence suggests this phenomenon can be assessed non-invasively by determining breath levels of the omega-3 polyunsaturated fatty acid (PUFA) oxidation product ethane. This study compares alkane levels in chronic, medicated, patients with schizophrenia or bipolar disorder with those in healthy controls. Both ethane and butane levels were significantly increased in patients with schizophrenia or bipolar disorder, although elevated butane levels were likely due to increased ambient gas concentrations. Ethane levels were not correlated with symptom severity or with erythrocyte omega-3 PUFA levels. Our results support the hypothesis that oxidative stress is elevated in patients with schizophrenia and bipolar disorder leading to increased breath ethane abundance. This does not appear to be caused by increased abundance of omega-3 PUFA, but rather is likely due to enhanced oxidative damage of these lipids. As such, breath hydrocarbon analysis may represent a simple, non-invasive means to monitor the metabolic processes occurring in these disorders. Copyright © 2010 Elsevier Inc. All rights reserved.

Effect of Opuntia ficus-indica flowers maceration on quality and on heat stability of olive oil.

PubMed

Ammar, Imène; BenAmira, Amal; Khemakem, Ibtihel; Attia, Hamadi; Ennouri, Monia

2017-05-01

This study was focused on the evaluation of the quality and the oxidative stability of olive oil added with Opuntia ficus - indica flowers. Two different amounts of O. ficus - indica flowers were considered 5 and 15% (w/w). The olive oils were evaluated towards their quality, fatty acids profile, total phenol contents and thermal properties by differential scanning calorimetry. The oxidative stability was also monitored by employing the Rancimat and the oven test based on accelerating the oxidation process during storage. The addition of O. ficus - indica flowers induced an increase in free acidity values and a variation in fatty acids profile of olive oils but values remained under the limits required for an extra-virgin olive oil. The obtained olive oils were nutritionally enriched due to the increase in their phenols content. The oxidative stability was generally improved, mainly in olive oil enriched with 5% Opuntia ficus - indica flowers. These findings proved that this enriched olive oil could be considered as a product with a greater added value.

Effect of light, packaging condition and dark storage durations on colour and lipid oxidative stability of cooked ham.

PubMed

Haile, Demewez Moges; De Smet, Stefaan; Claeys, Erik; Vossen, Els

2013-04-01

The colour and lipid oxidative stability of sliced cooked ham stored at 4 °C were studied in relation to dark storage duration, lighting and packaging conditions. Colour stability was monitored by instrumental colour measurement (CIE L*a*b* colour space) whereas lipid stability was measured by the determination of the 2-thiobarbituric acid reactive substances (TBARS). A significantly higher discoloration observed in products wrapped in foil and kept in light than products wrapped in foil and kept in dark. Colour loss was estimated by loss of redness (a*), a*/b*, nitrosomyoglobin, chroma (C); or increase of lightness (L*), MetMb, hue angle (H°). Colour loss was more dependent upon photochemical process than dark storage duration and packaging types. Lipid oxidation was not significantly affected by light exposure. However lipid oxidation was significantly affected by dark storage duration as noticed from better lipid stability of products stored for short duration in dark. Better colour stability was observed on products packed in MAP with less residual oxygen.

Calcium manganese oxides as oxygen evolution catalysts: O2 formation pathways indicated by 18O-labelling studies.

PubMed

Shevela, Dmitriy; Koroidov, Sergey; Najafpour, M Mahdi; Messinger, Johannes; Kurz, Philipp

2011-05-02

Oxygen evolution catalysed by calcium manganese and manganese-only oxides was studied in (18)O-enriched water. Using membrane-inlet mass spectrometry, we monitored the formation of the different O(2) isotopologues (16)O(2), (16)O(18)O and (18)O(2) in such reactions simultaneously with good time resolution. From the analysis of the data, we conclude that entirely different pathways of dioxygen formation catalysis exist for reactions involving hydrogen peroxide (H(2)O(2)), hydrogen persulfate (HSO(5)(-)) or single-electron oxidants such as Ce(IV) and [Ru(III) (bipy)(3)](3+) . Like the studied oxide catalysts, the active sites of manganese catalase and the oxygen-evolving complex (OEC) of photosystem II (PSII) consist of μ-oxido manganese or μ-oxido calcium manganese sites. The studied processes show very similar (18)O-labelling behaviour to the natural enzymes and are therefore interesting model systems for in vivo oxygen formation by manganese metalloenzymes such as PSII. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Titanium dioxide nanowire sensor array integration on CMOS platform using deterministic assembly.

PubMed

Gall, Oren Z; Zhong, Xiahua; Schulman, Daniel S; Kang, Myungkoo; Razavieh, Ali; Mayer, Theresa S

2017-06-30

Nanosensor arrays have recently received significant attention due to their utility in a wide range of applications, including gas sensing, fuel cells, internet of things, and portable health monitoring systems. Less attention has been given to the production of sensor platforms in the μW range for ultra-low power applications. Here, we discuss how to scale the nanosensor energy demand by developing a process for integration of nanowire sensing arrays on a monolithic CMOS chip. This work demonstrates an off-chip nanowire fabrication method; subsequently nanowires link to a fused SiO 2 substrate using electric-field assisted directed assembly. The nanowire resistances shown in this work have the highest resistance uniformity reported to date of 18%, which enables a practical roadmap towards the coupling of nanosensors to CMOS circuits and signal processing systems. The article also presents the utility of optimizing annealing conditions of the off-chip metal-oxides prior to CMOS integration to avoid limitations of thermal budget and process incompatibility. In the context of the platform demonstrated here, directed assembly is a powerful tool that can realize highly uniform, cross-reactive arrays of different types of metal-oxide nanosensors suited for gas discrimination and signal processing systems.

Titanium dioxide nanowire sensor array integration on CMOS platform using deterministic assembly

NASA Astrophysics Data System (ADS)

Gall, Oren Z.; Zhong, Xiahua; Schulman, Daniel S.; Kang, Myungkoo; Razavieh, Ali; Mayer, Theresa S.

2017-06-01

Nanosensor arrays have recently received significant attention due to their utility in a wide range of applications, including gas sensing, fuel cells, internet of things, and portable health monitoring systems. Less attention has been given to the production of sensor platforms in the μW range for ultra-low power applications. Here, we discuss how to scale the nanosensor energy demand by developing a process for integration of nanowire sensing arrays on a monolithic CMOS chip. This work demonstrates an off-chip nanowire fabrication method; subsequently nanowires link to a fused SiO2 substrate using electric-field assisted directed assembly. The nanowire resistances shown in this work have the highest resistance uniformity reported to date of 18%, which enables a practical roadmap towards the coupling of nanosensors to CMOS circuits and signal processing systems. The article also presents the utility of optimizing annealing conditions of the off-chip metal-oxides prior to CMOS integration to avoid limitations of thermal budget and process incompatibility. In the context of the platform demonstrated here, directed assembly is a powerful tool that can realize highly uniform, cross-reactive arrays of different types of metal-oxide nanosensors suited for gas discrimination and signal processing systems.

Identifying the Constituents of and Transformations in Diatomaceous Earth and Polysiloxane Foams Through the Use of Electron Paramagnetic Resonance Spectroscopy

NASA Astrophysics Data System (ADS)

Blair, Michael; Muenchausen, Ross; Bennett, Bryan; Smith, James; Stephens, Thomas; Cooke, Wayne

2007-03-01

The chemical aging of polymeric materials is largely governed by the characteristics of the storage environment. For polysiloxane foams, the diatomaceous earth (DE) filler is a small component of the foam, but it plays a large role in the handling of water in the system. The DE filler can act as either a ``source'' or a ``sink'' for water via both chemical hydroxylation/ dehydroxylation and physical adsorption/ desorption processes, depending on the processing history and storage conditions. We have used electron paramagnetic resonance (EPR) spectroscopy to examine composite foam material as well as the DE filler alone. Intense, broad (400 Gauss) resonances were recorded at room temperature as a function of the microwave power at X-band frequency. The observed spectra have been assigned to the iron oxide compounds goethite, lepidocrocite, hematite, and magnetite based upon the measured EPR spectra of these minerals. As the presence or absence of free H2O and the temperature of processing and storage also affects the interconversion of these various iron oxides, we indicate how this process can be followed by monitoring changes in the EPR spectra.

Scale-up of electrolytic and photoelectrolytic processes for water reclaiming: a preliminary study.

PubMed

Martín de Vidales, María J; Cotillas, Salvador; Perez-Serrano, José F; Llanos, Javier; Sáez, Cristina; Cañizares, Pablo; Rodrigo, Manuel A

2016-10-01

This work focuses on the scale-up of electrochemical and photoelectrochemical oxidation processes with diamond anodes for the removal of organic pollutants and disinfection of treated urban wastewater, two of the most important parameters for the reclaiming of wastewater. The removal of organics was studied with actual biologically treated urban wastewater intensified with 100 mg dm(-3) of caffeine, added as a trace organic pollutant. The disinfection was also studied with biologically treated urban wastewater, and Escherichia coli was used to monitor the efficiency of the process. Results obtained with a single DiaCell® 101 were compared with those obtained with a single-stack DiaCell® 1001 and with a pilot plant made up of five of these stacks. Results obtained demonstrate that scale-up is not a simple but a very complex process, in which not only the electrode and the irradiation dose are important but also mass transfer conditions. Enhanced mass transport conditions have a determining and very positive effect on the removal of organics and a negative effect on the disinfection. Likewise, ultraviolet (UV) irradiation affects in a different way in the different setups used, having a great influence on the removal of complex organics and on the speciation of oxidants produced during disinfection. This works helps to understand the key differences observed in the scale-up, and it is a first approach for future works focused on the real application of conductive diamond electrochemical oxidation.

Effects of irradiation on trans fatty acids formation in ground beef

NASA Astrophysics Data System (ADS)

Brito, Mônica S.; Villavicencio, Anna Lúcia C. H.; Mancini-filho, Jorge

2002-03-01

In order to give the consumer the assurance that meat processed by irradiation is a safe product, a great deal of research has been developed in the world. The effect of irradiation on the hygienic quality of meat and meat products is considered as related to the control of meat-borne parasites of humans; elimination of pathogens from fresh meat and poultry; and elimination of pathogens from processed meat. Lipid oxidation and associated changes are the major causes of the quality deterioration of meat during storage. Irradiation of lipids induces the production of free radicals, which react with oxygen, leading to the formation of carbonyls, responsible for alterations in food nutritional and sensorial characteristics. Trans fatty acids are present in ground beef and can also be formed during its processing. Interestingly, the trans fatty acids, due to their chemical and physical characteristics, show more resistance to the oxidizing process. This property motivated us to investigate the level of the trans fatty acids, as well as the level of oxidation in irradiated ground beef. Irradiation of ground beef was performed by gamma rays from a 60Co source. The applied radiation doses were 0; 1.0; 2.0; 3.0; 4.0; 5.0; 6.0; 7.0 and 8.0 kGy. Lipid peroxidation in terms of TBA number and carbonyl content was monitored during storage. The sample characteristics and trans fatty acids composition were measured, following irradiation and after 60 and 90 days of storage at -10°C.

A Continuous Flow System for the Measurement of Ambient Nitrogen Oxides [NO + NO2] Using Rhodamine B Hydrazide as a Chemosensor

PubMed Central

Malingappa, Pandurangappa; Yarradoddappa, Venkataramanappa

2014-01-01

A new chemosensor has been used to monitor atmospheric nitrogen oxides [NO + NO2] at parts per billion (ppb) level. It is based on the catalytic reaction of nitrogen oxides with rhodamine B hydrazide (RBH) to produce a colored compound through the hydrolysis of the amide bond of the molecule. A simple colorimeter has been used to monitor atmospheric nitrogen dioxide at ppb level. The air samples were purged through a sampling cuvette containing RBH solution using peristaltic pump. The proposed method has been successfully applied to monitor the ambient nitrogen dioxide levels at traffic junction points within the city limits and the results obtained are compared with the standard Griess-Ilosvay method. PMID:25210422

Nominations for the 2017 NNSA Pollution Prevention Awards

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

Salzman, Sonja L.; Ballesteros Rodriguez, Sonia; Lopez, Lorraine Bonds

In the field of nuclear forensics, one of the biggest challenges is to dissolve postdetonation debris for analysis. Debris generated after a nuclear detonation is a glassy material that is difficult to dissolve with chemicals. Traditionally, concentrated nitric acid, hydrofluoric acid, or sulfuric acid are employed during the dissolution. These acids, due to their corrosive nature, are not suitable for in-field/on-site sample preparations. Uranium oxides are commonly present in nuclear fuel processing plants and nuclear research facilities. In uranium oxides, the level of uranium isotope enrichment is a sensitive indicator for nuclear nonproliferation and is monitored closely by the Internationalmore » Atomic Energy Agency (IAEA) to ensure there is no misuse of nuclear material or technology for nuclear weapons. During an IAEA on-site inspection at a facility, environmental surface swipe samples are collected and transported to the IAEA headquarters or network of analytical laboratories for further processing. Uranium oxide particles collected on the swipe medium are typically dissolved with inorganic acids and are then analyzed for uranium isotopic compositions. To improve the responsiveness of on-site inspections, in-field detection techniques have been recently explored. However, in-field analysis is bottlenecked by time-consuming and hazardous dissolution procedures, as corrosive inorganic acids must be used. Corrosive chemicals are difficult to use in the field due to personnel safety considerations, and the transportation of such chemicals is highly regulated. It was therefore necessary to develop fast uranium oxide dissolution methods using less hazardous chemicals in support of the rapid infield detection of anomalies in declared nuclear processes.« less

Automated analysis of oxidative metabolites

NASA Technical Reports Server (NTRS)

Furner, R. L. (Inventor)

1974-01-01

An automated system for the study of drug metabolism is described. The system monitors the oxidative metabolites of aromatic amines and of compounds which produce formaldehyde on oxidative dealkylation. It includes color developing compositions suitable for detecting hyroxylated aromatic amines and formaldehyde.

Fluorescent Probes Used for Detection of Hydrogen Peroxide under Biological Conditions.

PubMed

Żamojć, Krzysztof; Zdrowowicz, Magdalena; Jacewicz, Dagmara; Wyrzykowski, Dariusz; Chmurzyński, Lech

2016-05-03

Hydrogen peroxide is a well-established precursor of reactive oxygen and nitrogen species that are known to contribute to oxidative stress-the crucial factor responsible for the course of a wide range of phy-sicochemical processes as well as the genesis of various diseases, such as cancer and neurodegenerative disorders. Thus, the development of sensitive and selective methods for the detection and quantitative determination of hydrogen peroxide is of great importance in monitoring the in vivo production of that species and elucidating its biological functions. This review highlights the progress that has been made in the development of fluorescent and luminescent probes (excluding nanoparticles) employed to monitor hydrogen peroxide under biological conditions. Attention was focused on probes developed in the past 10 years.

Sequential Combination of Electro-Fenton and Electrochemical Chlorination Processes for the Treatment of Anaerobically-Digested Food Wastewater.

PubMed

Shin, Yong-Uk; Yoo, Ha-Young; Kim, Seonghun; Chung, Kyung-Mi; Park, Yong-Gyun; Hwang, Kwang-Hyun; Hong, Seok Won; Park, Hyunwoong; Cho, Kangwoo; Lee, Jaesang

2017-09-19

A two-stage sequential electro-Fenton (E-Fenton) oxidation followed by electrochemical chlorination (EC) was demonstrated to concomitantly treat high concentrations of organic carbon and ammonium nitrogen (NH 4 + -N) in real anaerobically digested food wastewater (ADFW). The anodic Fenton process caused the rapid mineralization of phenol as a model substrate through the production of hydroxyl radical as the main oxidant. The electrochemical oxidation of NH 4 + by a dimensionally stable anode (DSA) resulted in temporal concentration profiles of combined and free chlorine species that were analogous to those during the conventional breakpoint chlorination of NH 4 + . Together with the minimal production of nitrate, this confirmed that the conversion of NH 4 + to nitrogen gas was electrochemically achievable. The monitoring of treatment performance with varying key parameters (e.g., current density, H 2 O 2 feeding rate, pH, NaCl loading, and DSA type) led to the optimization of two component systems. The comparative evaluation of two sequentially combined systems (i.e., the E-Fenton-EC system versus the EC-E-Fenton system) using the mixture of phenol and NH 4 + under the predetermined optimal conditions suggested the superiority of the E-Fenton-EC system in terms of treatment efficiency and energy consumption. Finally, the sequential E-Fenton-EC process effectively mineralized organic carbon and decomposed NH 4 + -N in the real ADFW without external supply of NaCl.

Monitoring one-electron photo-oxidation of guanine in DNA crystals using ultrafast infrared spectroscopy

NASA Astrophysics Data System (ADS)

Hall, James P.; Poynton, Fergus E.; Keane, Páraic M.; Gurung, Sarah P.; Brazier, John A.; Cardin, David J.; Winter, Graeme; Gunnlaugsson, Thorfinnur; Sazanovich, Igor V.; Towrie, Michael; Cardin, Christine J.; Kelly, John M.; Quinn, Susan J.

2015-12-01

To understand the molecular origins of diseases caused by ultraviolet and visible light, and also to develop photodynamic therapy, it is important to resolve the mechanism of photoinduced DNA damage. Damage to DNA bound to a photosensitizer molecule frequently proceeds by one-electron photo-oxidation of guanine, but the precise dynamics of this process are sensitive to the location and the orientation of the photosensitizer, which are very difficult to define in solution. To overcome this, ultrafast time-resolved infrared (TRIR) spectroscopy was performed on photoexcited ruthenium polypyridyl-DNA crystals, the atomic structure of which was determined by X-ray crystallography. By combining the X-ray and TRIR data we are able to define both the geometry of the reaction site and the rates of individual steps in a reversible photoinduced electron-transfer process. This allows us to propose an individual guanine as the reaction site and, intriguingly, reveals that the dynamics in the crystal state are quite similar to those observed in the solvent medium.

Knudsen pump produced via silicon deep RIE, thermal oxidation, and anodic bonding processes for on-chip vacuum pumping

NASA Astrophysics Data System (ADS)

Van Toan, Nguyen; Inomata, Naoki; Trung, Nguyen Huu; Ono, Takahito

2018-05-01

This work describes the fabrication and evaluation of the Knudsen pump for on-chip vacuum pumping that works based on the principle of a thermal transpiration. Three AFM (atomic force microscope) cantilevers are integrated into small chambers with a size of 5 mm  ×  3 mm  ×  0.4 mm for the pump’s evaluation. Knudsen pump is fabricated using deep RIE (reactive ion etching), wet thermal oxidation and anodic bonding processes. The fabricated device is evaluated by monitoring the quality (Q) factor of the integrated cantilevers. The Q factor of the cantilever is increased from 300 -1150 in cases without and with a temperature difference approximately 25 °C between the top (the hot side at 40 °C) and bottom (the cold side at 15 °C) sides of the fabricated device, respectively. The evacuated chamber pressure of around 10 kPa is estimated from the Q factor of the integrated cantilevers.

Monitoring one-electron photo-oxidation of guanine in DNA crystals using ultrafast infrared spectroscopy.

PubMed

Hall, James P; Poynton, Fergus E; Keane, Páraic M; Gurung, Sarah P; Brazier, John A; Cardin, David J; Winter, Graeme; Gunnlaugsson, Thorfinnur; Sazanovich, Igor V; Towrie, Michael; Cardin, Christine J; Kelly, John M; Quinn, Susan J

2015-12-01

To understand the molecular origins of diseases caused by ultraviolet and visible light, and also to develop photodynamic therapy, it is important to resolve the mechanism of photoinduced DNA damage. Damage to DNA bound to a photosensitizer molecule frequently proceeds by one-electron photo-oxidation of guanine, but the precise dynamics of this process are sensitive to the location and the orientation of the photosensitizer, which are very difficult to define in solution. To overcome this, ultrafast time-resolved infrared (TRIR) spectroscopy was performed on photoexcited ruthenium polypyridyl-DNA crystals, the atomic structure of which was determined by X-ray crystallography. By combining the X-ray and TRIR data we are able to define both the geometry of the reaction site and the rates of individual steps in a reversible photoinduced electron-transfer process. This allows us to propose an individual guanine as the reaction site and, intriguingly, reveals that the dynamics in the crystal state are quite similar to those observed in the solvent medium.

Electrical Characterization of Semiconductor and Dielectric Materials with a Non-Damaging FastGateTM Probe

NASA Astrophysics Data System (ADS)

Robert, Hillard; William, Howland; Bryan, Snyder

2002-03-01

Determination of the electrical properties of semiconductor materials and dielectrics is highly desirable since these correlate best to final device performance. The properties of SiO2 and high k dielectrics such as Equivalent Oxide Thickness(EOT), Interface Trap Density(Dit), Oxide Effective Charge(Neff), Flatband Voltage Hysteresis(Delta Vfb), Threshold Voltage(VT) and, bulk properties such as carrier density profile and channel dose are all important parameters that require monitoring during front end processing. Conventional methods for determining these parameters involve the manufacturing of polysilicon or metal gate MOS capacitors and subsequent measurements of capacitance-voltage(CV) and/or current-voltage(IV). These conventional techniques are time consuming and can introduce changes to the materials being monitored. Also, equivalent circuit effects resulting from excessive leakage current, series resistance and stray inductance can introduce large errors in the measured results. In this paper, a new method is discussed that provides rapid determination of these critical parameters and is robust against equivalent circuit errors. This technique uses a small diameter(30 micron), elastically deformed probe to form a gate for MOSCAP CV and IV and can be used to measure either monitor wafers or test areas within scribe lines on product wafers. It allows for measurements of dielectrics thinner than 10 Angstroms. A detailed description and applications such as high k dielectrics, will be presented.

Monitoring bisphosphonate surface functionalization and acid stability of hierarchically porous titanium zirconium oxides.

PubMed

Ide, Andreas; Drisko, Glenna L; Scales, Nicholas; Luca, Vittorio; Schiesser, Carl H; Caruso, Rachel A

2011-11-01

To take advantage of the full potential of functionalized transition metal oxides, a well-understood nonsilane based grafting technique is required. The functionalization of mixed titanium zirconium oxides was studied in detail using a bisphosphonic acid, featuring two phosphonic acid groups with high surface affinity. The bisphosphonic acid employed was coupled to a UV active benzamide moiety in order to track the progress of the surface functionalization in situ. Using different material compositions, altering the pH environment, and looking at various annealing conditions, key features of the functionalization process were identified that consequently will allow for intelligent material design. Loading with bisphosphonic acid was highest on supports calcined at 650 °C compared to lower calcination temperatures: A maximum capacity of 0.13 mmol g(-1) was obtained and the adsorption process could be modeled with a pseudo-second-order rate relationship. Heating at 650 °C resulted in a phase transition of the mixed binary oxide to a ternary oxide, titanium zirconium oxide in the srilankite phase. This phase transition was crucial in order to achieve high loading of the bisphosphonic acid and enhanced chemical stability in highly acidic solutions. Due to the inert nature of phosphorus-oxygen-metal bonds, materials functionalized by bisphosphonic acids showed increased chemical stability compared to their nonfunctionalized counterparts in harshly acidic solutions. Leaching studies showed that the acid stability of the functionalized material was improved with a partially crystalline srilankite phase. The materials were characterized using nitrogen sorption, X-ray powder diffraction, and UV-vis spectroscopy; X-ray photoelectron spectroscopy was used to study surface coverage with the bisphosphonic acid molecules.

Biomarkers of Oxidative Stress in the Assessment of Enantioselective Toxicity of Chiral Pesticides.

PubMed

Ye, Xiaoqing; Liu, Ying; Li, Feixue

2017-01-01

In biological systems, the individual stereoisomers of chiral substances possess significantly different biochemical properties because the specific structure-activity relationships are required for a common site on biomolecules. In the past decade, there has been increasing concern over the enantioselective toxicity of environmental chiral pollutants, especially chiral pesticides. Different responses and activities of a pair of enantiomers of chiral pesticides were often observed. Therefore, assessment of the enantioselective toxicological properties of chiral pesticides is a prerequisite in application of single-isomer products and particularly important for environmental protection. The development of biomarkers that can predict enantioselective effects from chiral pesticides has recently been gained more and more attention. The biomarkers of oxidative stress have become a topic of significant interest for toxic assessments. In this review, we summarized current knowledge and advances in the understanding of enantiomeric oxidative processes in biological systems in response to chiral pesticides. The consistent results in two types of chiral insecticides (synthetic pyrethroids and organochlorine pesticides) showed the significant difference in cytotoxicity of enantiomers, suggesting the antioxidant enzymes are reliable biomarkers for the assessment of toxicity of chiral chemicals. Results indicate that antioxidant enzymes are sensitive and valid biomarkers to assess the oxidative damage caused by chiral herbicides. In addition, it can be inferred that the enantioselectivity of chiral herbicides on antioxidant enzymes exists in other species. Compared with insecticides and herbicides, researches about the enantioselectivity of oxidative stress caused by chiral fungicides are quite limited. Only two kinds of chiral fungicides has been used to study the enantioselectivity of oxidative stress by now. The current knowledge that enantioselective processes of oxidative damage occur in organisms or cells extends toxicological studies of environmental contamination by chiral chemicals. These studies indicate that oxidative biomarkers can be useful for monitoring enantioselective toxicity of chiral contaminates, while comparing enantiomer-induced responses in different species should be approached with caution because of differences in uptake, target sites, biotransformation and pharmacokinetics of the enantiomers.

“Transference Ratios” to Predict Total Oxidized Sulfur and Nitrogen Deposition – Part I, Monitoring Results

EPA Science Inventory

Use of model-predicted “transference ratios” is currently under consideration by the US EPA in the formulation of a Secondary National Ambient Air Quality Standard for oxidized nitrogen and oxidized sulfur. This term is an empirical parameter defined for oxidized sulfur (TS)as th...

Chronoamperometric study of mild steel pitting in sodium sulfide aqueous solution

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

Otero, T.F.; Achucarro, C.

1994-08-01

Mild steel samples were studied by chronoamperometry in sodium sulfide (Na[sub 2]S) aqueous solution. Pit nucleation and growth also were monitored by optical microscopy. The influence of variables such as temperature, polarization potential, surface roughness, the presence of electrochemically generated oxide layers, and the simultaneous presence of potassium hydroxide (KOH) was studied. The influence of each parameter on pit shape and growth was reviewed. Different reactions and competitive processes were proposed based on the experimental results.

Non-Invasive Monitoring of Breast Tumor Oxygenation: A Key to Tumor Therapy Planning and Tumor Prognosis

DTIC Science & Technology

2004-09-01

data processing. We vations could have value in the clinic. The major gratefully acknowledge Weina Cui for helpful discus- deficiency in our current NIR...of vascular volume markers such as the super paramagnetic iron oxide particles (SPIOs) [42-43] in place of the 𔄃F NMR approach used here. Since...Flow and Oxygen Dependant contrast) MRI of G3H prolactinomas , a highly vascularized and perfused tumor type, showed some response to the addition

Development of a Scalable Process Control System for Chemical Soil Washing to Remove Uranyl Oxide

DTIC Science & Technology

2015-05-01

ICET also has a fully equipped counting laboratory for the evaluation of radioactive samples . Photographs of the 1-meter and 3-meter motorized...the leachate will be monitored using a gamma detector. There are numerous naturally occurring radioactive materials in soil . ICET has developed a...48.6% from 238U and 49.2% from 234U. The 238U in NU also contains daughters that are radioactive . This increases the activity of samples over long

Direct detection of the triphenylpyrylium-derived short-lived intermediates in the photocatalyzed degradation of acetaminophen, acetamiprid, caffeine and carbamazepine.

PubMed

Martinez-Haya, R; Gomis, J; Arques, A; Amat, A M; Miranda, M A; Marin, M L

2017-09-09

Advanced oxidation processes are useful methodologies to accomplish abatement of contaminants; however, elucidation of the reaction mechanisms is hampered by the difficult detection of the short-lived primary key species involved in the photocatalytic processes. Nevertheless, herein the combined use of an organic photocatalyst such as triphenylpyrylium (TPP + ) and photophysical techniques based on emission and absorption spectroscopy allowed monitoring the photocatalyst-derived short-lived intermediates. This methodology has been applied to the photocatalyzed degradation of different pollutants, such as acetaminophen, acetamiprid, caffeine and carbamazepine. First, photocatalytic degradation of a mixture of the pollutants showed that acetaminophen was the most easily photodegraded, followed by carbamazepine and caffeine, being the abatement of acetamiprid almost negligible. This process was accompanied by mineralization, as demonstrated by trapping of carbon dioxide using barium hydroxide. Then, emission spectroscopy measurements (steady-state and time-resolved fluorescence) allowed demonstrating quenching of the singlet excited state of TPP + . Laser flash photolysis experiments with absorption detection showed that oxidation of contaminants is accompanied by TPP + reduction, with formation of a pyranyl radical (TPP), that constituted a fingerprint of the redox nature of the occurring process. The relative amounts of TPP detected was also correlated with the efficiency of the photodegradation process. Copyright © 2017 Elsevier B.V. All rights reserved.

In Situ Investigation of Electrochemically Mediated Surface-Initiated Atom Transfer Radical Polymerization by Electrochemical Surface Plasmon Resonance.

PubMed

Chen, Daqun; Hu, Weihua

2017-04-18

Electrochemically mediated atom transfer radical polymerization (eATRP) initiates/controls the controlled/living ATRP chain propagation process by electrochemically generating (regenerating) the activator (lower-oxidation-state metal complex) from deactivator (higher-oxidation-state metal complex). Despite successful demonstrations in both of the homogeneous polymerization and heterogeneous systems (namely, surface-initiated ATRP, SI-ATRP), the eATRP process itself has never been in situ investigated, and important information regarding this process remains unrevealed. In this work, we report the first investigation of the electrochemically mediated SI-ATRP (eSI-ATRP) by rationally combining the electrochemical technique with real-time surface plasmon resonance (SPR). In the experiment, the potential of a SPR gold chip modified by the self-assembled monolayer of the ATRP initiator was controlled to electrochemically reduce the deactivator to activator to initiate the SI-ATRP, and the whole process was simultaneously monitored by SPR with a high time resolution of 0.1 s. It is found that it is feasible to electrochemically trigger/control the SI-ATRP and the polymerization rate is correlated to the potential applied to the gold chip. This work reveals important kinetic information for eSI-ATRP and offers a powerful platform for in situ investigation of such complicated processes.

Direct detection of the triphenylpyrylium-derived short-lived intermediates in the photocatalyzed degradation of acetaminophen, acetamiprid, caffeine and carbamazepine.

PubMed

Martinez-Haya, R; Gomis, J; Arques, A; Amat, A M; Miranda, M A; Marin, M L

2018-08-15

Advanced oxidation processes are useful methodologies to accomplish abatement of contaminants; however, elucidation of the reaction mechanisms is hampered by the difficult detection of the short-lived primary key species involved in the photocatalytic processes. Nevertheless, herein the combined use of an organic photocatalyst such as triphenylpyrylium (TPP + ) and photophysical techniques based on emission and absorption spectroscopy allowed monitoring the photocatalyst-derived short-lived intermediates. This methodology has been applied to the photocatalyzed degradation of different pollutants, such as acetaminophen, acetamiprid, caffeine and carbamazepine. First, photocatalytic degradation of a mixture of the pollutants showed that acetaminophen was the most easily photodegraded, followed by carbamazepine and caffeine, being the abatement of acetamiprid almost negligible. This process was accompanied by mineralization, as demonstrated by trapping of carbon dioxide using barium hydroxide. Then, emission spectroscopy measurements (steady-state and time-resolved fluorescence) allowed demonstrating quenching of the singlet excited state of TPP + . Laser flash photolysis experiments with absorption detection showed that oxidation of contaminants is accompanied by TPP + reduction, with formation of a pyranyl radical (TPP), that constituted a fingerprint of the redox nature of the occurring process. The relative amounts of TPP detected was also correlated with the efficiency of the photodegradation process. Copyright © 2018. Published by Elsevier B.V.

Advanced oxidation of acridine orange by aqueous alkaline iodine.

PubMed

Azmat, Rafia; Qamar, Noshab; Naz, Raheela; Khursheed, Anum

2016-11-01

The advanced oxidation process is certainly used for the dye waste water treatment. In this continuation a new advanced oxidation via aqueous alkaline iodine was developed for the oxidation of acridine orange (AO) {3, 6 -bis (dimethylamino) acridine zinc chloride double salt}. Oxidation Kinetics of AO by alkaline solution of iodine was investigated spectrophotometrically at λ max 491 nm. The reaction was monitored at various operational parameters like several concentrations of dye and iodine, pH, salt electrolyte and temperature. The initial steps of oxidation kinetics followed fractional order reaction with respect to the dye while depend upon the incremental amount of iodine to certain extent whereas maximum oxidation of AO was achieved at high pH. Decline in the reaction rate in the presence of salt electrolyte suggested the presence of oppositely charged species in the rate determining step. Kinetic data revealed that the de-colorization mechanism involves triodate (I 3 - ) species, instead of hypoidate (OI - ) and hypiodous acid (HOI), in alkaline medium during the photo-excitation of hydrolyzed AO. Alleviated concentration of alkali result in decreasing of rate of reaction, clearly indicate that the iodine species are active oxidizing species instead of OH radical. Activation parameters at elevated temperatures were determined which revealed that highly solvated state of dye complex existed into solution. Reaction mixture was subjected to UV/Visible and GC mass spectrum analysis that proves the secondary consecutive reaction was operative in rate determining step and finally dye complex end into smaller fragments.

40 CFR 63.2987 - What must my operation, maintenance, and monitoring (OMM) plan include?

Code of Federal Regulations, 2010 CFR

2010-07-01

..., maintenance, and monitoring (OMM) plan include? (a) You must prescribe the monitoring that will be performed...) For the burn cycle that follows the inspection, document that the thermal oxidizer is operating...

In situ x-ray surface diffraction chamber for pulsed laser ablation film growth studies

NASA Astrophysics Data System (ADS)

Tischler, J. Z.; Eres, G.; Lowndes, D. H.; Larson, B. C.; Yoon, M.; Chiang, T.-C.; Zschack, Paul

2000-06-01

Pulsed laser deposition is highly successful for growing complex films such as oxides for substrate buffer layers and HiTc oxide superconductors. A surface diffraction chamber has been constructed to study fundamental aspects of non-equilibrium film growth using pulsed laser deposition. Due to the pulsed nature of the ablating laser, the deposited atoms arrive on the substrate in short sub-millisecond pulses. Thus monitoring the surface x-ray diffraction following individual laser pulses (with resolution down to ˜1 ms) provides direct information on surface kinetics and the aggregation process during film growth. The chamber design, based upon a 2+2 surface diffraction geometry with the modifications necessary for laser ablation, is discussed, and initial measurements on homo-epitaxial growth of SrTiO3 are presented.

Application of excitation and emission matrix fluorescence (EEM) and UV-vis absorption to monitor the characteristics of Alizarin Red S (ARS) during electro-Fenton degradation process.

PubMed

Lai, Bo; Zhou, Yuexi; Wang, Juling; Yang, Zhishan; Chen, Zhiqiang

2013-11-01

Oxidative degradation of Alizarin Red S (ARS) in aqueous solutions by using electro-Fenton was studied. At first, effect of operating parameters such as current density, aeration rate and initial pH on the degradation of ARS were studied by using UV-vis spectrum, respectively. Then, under the optimal operating conditions (current density: 10.0mAcm(-2), aeration rate: 1000mLmin(-1), initial pH: 2.8), the identification of degradation products of ARS was carried out by using GC-MS and HPLC, meanwhile its degradation pathway was proposed according to the intermediates. Considering the location, intensity and intensity ratio of fluorescence center peak of the ARS in aqueous solution, a convenient and quick monitoring method by using excitation-emission matrix fluorescence spectrum technology was developed to monitor the degradation degree of ARS through electro-Fenton process. Furthermore, it is suggested that the developed method would be promising for the quick analysis and evaluation of the degradation degree of the pollutants with π-conjugated system. Copyright © 2013 Elsevier Ltd. All rights reserved.

Sample environment for in situ synchrotron corrosion studies of materials in extreme environments

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

Elbakhshwan, Mohamed S.; Gill, Simerjeet K.; Motta, Arthur T.

A new in situ sample environment has been designed and developed to study the interfacial interactions of nuclear cladding alloys with high temperature steam. The sample environment is particularly optimized for synchrotron X-ray diffraction (XRD) studies for in situ structural analysis. The sample environment is highly corrosion resistant and can be readily adapted for steam environments. The in situ sample environment design complies with G2 ASTM standards for studying corrosion in zirconium and its alloys and offers remote temperature and pressure monitoring during the in situ data collection. The use of the in situ sample environment is exemplified by monitoringmore » the oxidation of metallic zirconium during exposure to steam at 350°C. Finally, the in situ sample environment provides a powerful tool for fundamental understanding of corrosion mechanisms by elucidating the substoichiometric oxide phases formed during early stages of corrosion, which can provide a better understanding the oxidation process.« less

Ultra-Low-Power Smart Electronic Nose System Based on Three-Dimensional Tin Oxide Nanotube Arrays.

PubMed

Chen, Jiaqi; Chen, Zhuo; Boussaid, Farid; Zhang, Daquan; Pan, Xiaofang; Zhao, Huijuan; Bermak, Amine; Tsui, Chi-Ying; Wang, Xinran; Fan, Zhiyong

2018-06-04

In this work, we present a high-performance smart electronic nose (E-nose) system consisting of a multiplexed tin oxide (SnO 2 ) nanotube sensor array, read-out circuit, wireless data transmission unit, mobile phone receiver, and data processing application (App). Using the designed nanotube sensor device structure in conjunction with multiple electrode materials, high-sensitivity gas detection and discrimination have been achieved at room temperature, enabling a 1000 times reduction of the sensor's power consumption as compared to a conventional device using thin film SnO 2 . The experimental results demonstrate that the developed E-nose can identify indoor target gases using a simple vector-matching gas recognition algorithm. In addition, the fabricated E-nose has achieved state-of-the-art sensitivity for H 2 and benzene detection at room temperature with metal oxide sensors. Such a smart E-nose system can address the imperative needs for distributed environmental monitoring in smart homes, smart buildings, and smart cities.

Sample environment for in situ synchrotron corrosion studies of materials in extreme environments

DOE PAGES

Elbakhshwan, Mohamed S.; Gill, Simerjeet K.; Motta, Arthur T.; ...

2016-10-25

A new in situ sample environment has been designed and developed to study the interfacial interactions of nuclear cladding alloys with high temperature steam. The sample environment is particularly optimized for synchrotron X-ray diffraction (XRD) studies for in situ structural analysis. The sample environment is highly corrosion resistant and can be readily adapted for steam environments. The in situ sample environment design complies with G2 ASTM standards for studying corrosion in zirconium and its alloys and offers remote temperature and pressure monitoring during the in situ data collection. The use of the in situ sample environment is exemplified by monitoringmore » the oxidation of metallic zirconium during exposure to steam at 350°C. Finally, the in situ sample environment provides a powerful tool for fundamental understanding of corrosion mechanisms by elucidating the substoichiometric oxide phases formed during early stages of corrosion, which can provide a better understanding the oxidation process.« less

40 CFR 60.1235 - How are the data from the continuous emission monitoring systems used?

Code of Federal Regulations, 2013 CFR

2013-07-01

... emission monitoring systems used? 60.1235 Section 60.1235 Protection of Environment ENVIRONMENTAL... Continuous Emission Monitoring § 60.1235 How are the data from the continuous emission monitoring systems... oxides, and carbon monoxide to demonstrate continuous compliance with the emission limits specified in...

40 CFR 60.1235 - How are the data from the continuous emission monitoring systems used?

Code of Federal Regulations, 2014 CFR

2014-07-01

... emission monitoring systems used? 60.1235 Section 60.1235 Protection of Environment ENVIRONMENTAL... Continuous Emission Monitoring § 60.1235 How are the data from the continuous emission monitoring systems... oxides, and carbon monoxide to demonstrate continuous compliance with the emission limits specified in...

40 CFR 60.1235 - How are the data from the continuous emission monitoring systems used?

Code of Federal Regulations, 2012 CFR

2012-07-01

... emission monitoring systems used? 60.1235 Section 60.1235 Protection of Environment ENVIRONMENTAL... Continuous Emission Monitoring § 60.1235 How are the data from the continuous emission monitoring systems... oxides, and carbon monoxide to demonstrate continuous compliance with the emission limits specified in...

Determination of Insulator-to-Semiconductor Transition in Sol-Gel Oxide Semiconductors Using Derivative Spectroscopy.

PubMed

Lee, Woobin; Choi, Seungbeom; Kim, Kyung Tae; Kang, Jingu; Park, Sung Kyu; Kim, Yong-Hoon

2015-12-23

We report a derivative spectroscopic method for determining insulator-to-semiconductor transition during sol-gel metal-oxide semiconductor formation. When an as-spun sol-gel precursor film is photochemically activated and changes to semiconducting state, the light absorption characteristics of the metal-oxide film is considerable changed particularly in the ultraviolet region. As a result, a peak is generated in the first-order derivatives of light absorption ( A' ) vs. wavelength (λ) plots, and by tracing the peak center shift and peak intensity, transition from insulating-to-semiconducting state of the film can be monitored. The peak generation and peak center shift are described based on photon-energy-dependent absorption coefficient of metal-oxide films. We discuss detailed analysis method for metal-oxide semiconductor films and its application in thin-film transistor fabrication. We believe this derivative spectroscopy based determination can be beneficial for a non-destructive and a rapid monitoring of the insulator-to-semiconductor transition in sol-gel oxide semiconductor formation.

Electronically conductive perovskite-based oxide nanoparticles and films for optical sensing applications

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

Ohodnicki, Jr., Paul R; Schultz, Andrew M

2015-04-28

The disclosure relates to a method of detecting a change in a chemical composition by contacting a electronically conducting perovskite-based metal oxide material with a monitored stream, illuminating the electronically conducting perovskite-based metal oxide with incident light, collecting exiting light, monitoring an optical signal based on a comparison of the incident light and the exiting light, and detecting a shift in the optical signal. The electronically conducting perovskite-based metal oxide has a perovskite-based crystal structure and an electronic conductivity of at least 10.sup.-1 S/cm, where parameters are specified at the gas stream temperature. The electronically conducting perovskite-based metal oxide hasmore » an empirical formula A.sub.xB.sub.yO.sub.3-.delta., where A is at least a first element at the A-site, B is at least a second element at the B-site, and where 0.8« less

Kinetic study of olive oil degradation monitored by fourier transform infrared spectrometry. Application to oil characterization.

PubMed

Román Falcó, Iván P; Grané Teruel, Nuria; Prats Moya, Soledad; Martín Carratalá, M Luisa

2012-11-28

A new approach for the determination of kinetic parameters of the cis/trans isomerization during the oxidation process of 24 virgin olive oils belonging to 8 different varieties is presented. The accelerated process of degradation at 100 °C was monitored by recording the Fourier transform infrared spectra. The parameters obtained confirm pseudo-first-order kinetics for the degradation of cis and the appearance of trans double bonds. The kinetic approach affords the induction time and the rate coefficient; these parameters are related to the fatty acid profile of the fresh olive oils. The data obtained were used to compare the oil stability of the samples with the help of multivariate statistical techniques. Fatty acid allowed a classification of the samples in five groups, one of them constituted by the cultivars with higher stability. Meanwhile, the kinetic parameters showed greater ability for the characterization of olive oils, allowing the classification in seven groups.

A Quadrupole Dalton-based multi-attribute method for product characterization, process development, and quality control of therapeutic proteins.

PubMed

Xu, Weichen; Jimenez, Rod Brian; Mowery, Rachel; Luo, Haibin; Cao, Mingyan; Agarwal, Nitin; Ramos, Irina; Wang, Xiangyang; Wang, Jihong

2017-10-01

During manufacturing and storage process, therapeutic proteins are subject to various post-translational modifications (PTMs), such as isomerization, deamidation, oxidation, disulfide bond modifications and glycosylation. Certain PTMs may affect bioactivity, stability or pharmacokinetics and pharmacodynamics profile and are therefore classified as potential critical quality attributes (pCQAs). Identifying, monitoring and controlling these PTMs are usually key elements of the Quality by Design (QbD) approach. Traditionally, multiple analytical methods are utilized for these purposes, which is time consuming and costly. In recent years, multi-attribute monitoring methods have been developed in the biopharmaceutical industry. However, these methods combine high-end mass spectrometry with complicated data analysis software, which could pose difficulty when implementing in a quality control (QC) environment. Here we report a multi-attribute method (MAM) using a Quadrupole Dalton (QDa) mass detector to selectively monitor and quantitate PTMs in a therapeutic monoclonal antibody. The result output from the QDa-based MAM is straightforward and automatic. Evaluation results indicate this method provides comparable results to the traditional assays. To ensure future application in the QC environment, this method was qualified according to the International Conference on Harmonization (ICH) guideline and applied in the characterization of drug substance and stability samples. The QDa-based MAM is shown to be an extremely useful tool for product and process characterization studies that facilitates facile understanding of process impact on multiple quality attributes, while being QC friendly and cost-effective.

Nitrous oxide emissions and dissolved oxygen profiling in a full-scale nitrifying activated sludge treatment plant.

PubMed

Aboobakar, Amina; Cartmell, Elise; Stephenson, Tom; Jones, Mark; Vale, Peter; Dotro, Gabriela

2013-02-01

This paper reports findings from online, continuous monitoring of dissolved and gaseous nitrous oxide (N₂O), combined with dissolved oxygen (DO) and ammonia loading, in a full-scale nitrifying activated sludge plant. The study was conducted over eight weeks, at a 210,000 population equivalent sewage treatment works in the UK. Results showed diurnal variability in the gaseous and dissolved N₂O emissions, with hourly averages ranging from 0 to 0.00009 kgN₂O-N/h for dissolved and 0.00077-0.0027 kgN₂O-N/h for gaseous nitrous oxide emissions respectively, per ammonia loading, depending on the time of day. Similarly, the spatial variability was high, with the highest emissions recorded immediately after the anoxic zone and in the final pass of the aeration lane, where ammonia concentrations were typically below 0.5 mg/L. Emissions were shown to be negatively correlated to dissolved oxygen, which fluctuated between 0.5 and 2.5 mgO₂/L, at the control set point of 1.5 mgO₂/L. The resulting dynamic DO conditions are known to favour N₂O production, both by autotrophic and heterotrophic processes in mixed cultures. Average mass emissions from the lane were greater in the gaseous (0.036% of the influent total nitrogen) than in the dissolved (0.01% of the influent total nitrogen) phase, and followed the same diurnal and spatial patterns. Nitrous oxide emissions corresponded to over 34,000 carbon dioxide equivalents/year, adding 13% to the carbon footprint associated with the energy requirements of the monitored lane. A clearer understanding of emissions obtained from real-time data can help towards finding the right balance between improving operational efficiency and saving energy, without increasing N₂O emissions. Copyright © 2012 Elsevier Ltd. All rights reserved.

Developing immune function assays to monitor fish health in field studies

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

Rice, C.D.; Kergosien, D.H.; Adams, S.M.

1995-12-31

The East Fork Poplar Creek system, a 24km long stream in TN that receives point source discharges of contaminants near its headwaters, was chosen to evaluate a field approach to fish immunotoxicology. Previous studies in this stream have shown that cytochrome P4501A activity, liver somatic indices, macrophage aggregates, and parasitic liver lesions are significantly elevated in sunfish with the degree of impact decreasing with distance from the contaminant source. Red-breasted sunfish were collected between May 23 and June 3 of 1994. Captured fish were anesthetized in MS-222 and processed by two different methods. One group was sacrificed at each samplingmore » station, weights and lengths recorded, and the spleen and anterior kidney tissues removed and placed in buffer on ice. The other group was kept in MS-222 for 2 hr and transported to the laboratory. The spleen and anterior kidney from each fish were then prepared as a single cell suspension and shipped overnight to Mississippi State University. Cells were then washed by centrifugation and resuspended in appropriate media to evaluate PMA-stimulated phagocyte oxidative burst and non-specific cytotoxic cell (NCC) activity against K562 tumor targets. Oxidative burst responses were dramatically suppressed in both groups at stations near the headwaters but returned to reference levels further downstream. There were no differences between treatment groups at each station. NCC activities did not follow gradient-response patterns observed with phagocyte oxidative burst data and there were inconsistent differences between treatment groups at each station. These data show that simple immune function assays, such as phagocyte oxidative burst responses, can be used as an ancillary biomarker in fish health monitoring.« less

Oxidative degradation of chlorophenol derivatives promoted by microwaves or power ultrasound: a mechanism investigation.

PubMed

Cravotto, Giancarlo; Binello, Arianna; Di Carlo, Stefano; Orio, Laura; Wu, Zhi-Lin; Ondruschka, Bernd

2010-03-01

Phenols are the most common pollutants in industrial wastewaters (particularly from oil refineries, resin manufacture, and coal processing). In the last two decades, it has become common knowledge that they can be effectively destroyed by nonconventional techniques such as power ultrasound (US) and/or microwave (MW) irradiation. Both techniques may strongly promote advanced oxidation processes (AOPs). The present study aimed to shed light on the effect and mechanism of US- and MW-promoted oxidative degradation of chlorophenols; 2,4-dichlorophenoxyacetic acid (2,4-D), a pesticide widespread in the environment, was chosen as the model compound. 2,4-D degradation by AOPs was carried out either under US (20 and 300 kHz) in aqueous solutions (with and without the addition of Fenton reagent) or solvent-free under MW with sodium percarbonate (SPC). All these reactions were monitored by gas chromatography-mass spectrometry (GC-MS) analysis and compared with the classical Fenton reaction in water under magnetic stirring. The same set of treatments was also applied to 2,4-dichlorophenol (2,4-DCP) and phenol, the first two products that occur a step down in the degradation sequence. Fenton and Fenton-like reagents were employed at the lowest active concentration. The effects of US and MW irradiation were investigated and compared with those of conventional treatments. Detailed mechanisms of Fenton-type reactions were suggested for 2,4-D, 2,4-DCP, and phenol, underlining the principal degradation products identified. MW-promoted degradation under solvent-free conditions with solid Fenton-like reagents (viz. SPC) is extremely efficient and mainly follows pyrolytic pathways. Power US strongly accelerates the degradation of 2,4-D in water through a rapid generation of highly reactive radicals; it does not lead to the formation of more toxic dimers. We show that US and MW enhance the oxidative degradation of 2,4-D and that a considerable saving of oxidants and cutting down of reaction times is thereby achieved. The results support the interpretation of previously published data and improve the understanding of the factors of direct degradation along different pathways. Oxidative pathways for 2,4-D, 2,4-DCP, and phenol were proposed by a careful monitoring of the reactions and detection of intermediates by GC-MS. The understanding of the factors that affect chlorophenols degradation along different pathways may facilitate the optimization of the treatment. Type of energy source (US or MW), power, and frequency to be applied could be designed in function of the operative scenario (amount of pollutant in soil, water, or oils).

Flow field and dissolved oxygen distributions in the outer channel of the Orbal oxidation ditch by monitor and CFD simulation.

PubMed

Guo, Xuesong; Zhou, Xin; Chen, Qiuwen; Liu, Junxin

2013-04-01

In the Orbal oxidation ditch, denitrification is primarily accomplished in the outer channel. However, the detailed characteristics of the flow field and dissolved oxygen (DO) distribution in the outer channel are not well understood. Therefore, in this study, the flow velocity and DO concentration in the outer channel of an Orbal oxidation ditch system in a wastewater treatment plant in Beijing (China) were monitored under actual operation conditions. The flow field and DO concentration distributions were analyzed by computed fluid dynamic modeling. In situ monitoring and modeling both showed that the flow velocity was heterogeneous in the outer channel. As a result, the DO was also heterogeneously distributed in the outer channel, with concentration gradients occurring along the flow direction as well as in the cross-section. This heterogeneous DO distribution created many anoxic and aerobic zones, which may have facilitated simultaneous nitrification-denitrification in the channel. These findings may provide supporting information for rational optimization of the performance of the Orbal oxidation ditch.

Reaction Mechanisms of Metals with Hydrogen Sulfide and Thiols in Model Wine. Part 1: Copper-Catalyzed Oxidation.

PubMed

Kreitman, Gal Y; Danilewicz, John C; Jeffery, David W; Elias, Ryan J

2016-05-25

Sulfidic off-odors as a result of hydrogen sulfide (H2S) and low-molecular-weight thiols are commonly encountered in wine production. These odors are usually removed by the process of Cu(II) fining, a process that remains poorly understood. The present study aims to elucidate the underlying mechanisms by which Cu(II) interacts with H2S and thiol compounds (RSH) under wine-like conditions. Copper complex formation was monitored along with H2S, thiol, oxygen, and acetaldehyde concentrations after the addition of Cu(II) (50 or 100 μM) to air-saturated model wine solutions containing H2S, cysteine, 6-sulfanylhexan-1-ol, or 3-sulfanylhexan-1-ol (300 μM each). The presence of H2S and thiols in excess to Cu(II) led to the rapid formation of ∼1.4:1 H2S/Cu and ∼2:1 thiol/Cu complexes, resulting in the oxidation of H2S and thiols and reduction of Cu(II) to Cu(I), which reacted with oxygen. H2S was observed to initially oxidize rather than form insoluble copper sulfide. The proposed reaction mechanisms provide insight into the extent to which H2S can be selectively removed in the presence of thiols in wine.

NMR data (ppm) from liver cells exposed to surfactant-wrapped (SDS) and oxidized (-OH) multi-walled carbon nanotubes (MWCNTs)

EPA Pesticide Factsheets

Carbon nanotubes (CNTs) have great potential in industrial, consumer, and mechanical applications, based partly on their unique structural, optical and electronic properties. CNTs are commonly oxidized or treated with surfactants to facilitate aqueous solution processing, and these CNT surface modifications also increase possible human and ecological exposures to nanoparticle-contaminated waters. To determine the exposure outcomes of oxidized and surfactant-wrapped multiwalled carbon nanotubes (MWCNTs) on biochemical processes, metabolomics based profiling of human liver cells (C3A) was utilized. Cells were exposed to 0, 10, or 100 ng/mL of MWCNTs for 24 and 48 hr. MWCNT particle size distribution, charge, and aggregation were monitored concurrently during exposures. Following MWCNT exposure, cellular metabolites were extracted, lyophilized, and buffered for 1H NMR analysis. Acquired spectra were subjected to both multivariate and univariate analysis to determine the consequences of nanotube exposure on the metabolite profile of C3A cells. Resulting scores plots illustrated temporal and dose-dependent metabolite responses to all MWCNTs tested. Loadings plots coupled with t-test filtered spectra identified metabolites of interest. XPS analysis revealed the presence of hydroxyl and carboxyl functionalities on both MWCNTs surfaces. Metal content analysis by ICP-AES indicated that the total mass concentration of the potentially toxic impurities in the exposure exper

Removal of artificial sweetener aspartame from aqueous media by electrochemical advanced oxidation processes.

PubMed

Lin, Heng; Oturan, Nihal; Wu, Jie; Sharma, Virender K; Zhang, Hui; Oturan, Mehmet A

2017-01-01

The degradation and mineralization of aspartame (ASP) in aqueous solution were investigated, for the first time, by electrochemical advanced oxidation processes (EAOPs) in which hydroxyl radicals were formed concomitantly in the bulk from Fenton reaction via in situ electrogenerated Fenton's reagent and at the anode surface from the water oxidation. Experiments were performed in an undivided cylindrical glass cell with a carbon-felt cathode and a Pt or boron-doped diamond (BDD) anode. The effect of Fe 2+ concentration and applied current on the degradation and mineralization kinetics of ASP was evaluated. The absolute rate constant for the reaction between ASP and OH was determined as (5.23 ± 0.02) × 10 9  M -1  s -1 by using the competition kinetic method. Almost complete mineralization of ASP was achieved with BDD anode at 200 mA constant current electrolysis. The formation and generation of the formed carboxylic acids (as ultimate end products before complete mineralization) and released inorganic ion were monitored by ion-exclusion high performance liquid chromatography (HPLC) and ion chromatography techniques, respectively. The global toxicity of the treated ASP solution during treatment was assessed by the Microtox ® method using V. fischeri bacteria luminescence inhibition. Copyright © 2016 Elsevier Ltd. All rights reserved.

Optimization of Fenton's oxidation of herbicide dicamba in water using response surface methodology

NASA Astrophysics Data System (ADS)

Sangami, Sanjeev; Manu, Basavaraju

2017-12-01

In this study Fenton's oxidation of dicamba in aqueous medium was investigated by using the response surface methodology. The influence of H2O2/COD ( A), H2O2/Fe2+ ( B), pH ( C) and reaction time ( D) as independent variables were studied on two responses (COD and dicamba removal efficiency). The dosage of H2O2 (5.35-17.4 mM) and Fe2+ (0.09-2.13 mM) were varied and optimum percentage removal of dicamba of 84.01% with H2O2 and Fe2+ dosage of 11.38 and 0.33 mM respectively. The whole oxidation process was monitored by high performance liquid chromatography (HPLC) along with liquid chromatography/mass spectrometry (LC/MS). It was found that 82% of dicamba was mineralized to oxalic acid, chloride ion, CO2 and H2O, which was confirmed with COD removal of 81.53%. The regression analysis was performed, in which standard deviation (<4%), coefficient of variation (<8), F value (Fisher's Test) (>2.74), coefficient of correlation ( R 2 = R_{adj}2) and adequate precision (>12) were in good agreement with model values. Finally, the treatment process was validated by performing the additional experiments.

Chemical composition, sources and secondary processes of aerosols in Baoji city of northwest China

NASA Astrophysics Data System (ADS)

Wang, Y. C.; Huang, R.-J.; Ni, H. Y.; Chen, Y.; Wang, Q. Y.; Li, G. H.; Tie, X. X.; Shen, Z. X.; Huang, Y.; Liu, S. X.; Dong, W. M.; Xue, P.; Fröhlich, R.; Canonaco, F.; Elser, M.; Daellenbach, K. R.; Bozzetti, C.; El Haddad, I.; Prévôt, A. S. H.; Canagaratna, M. R.; Worsnop, D. R.; Cao, J. J.

2017-06-01

Particulate air pollution is a severe environmental problem in China, affecting visibility, air quality, climate and human health. However, previous studies focus mainly on large cities such as Beijing, Shanghai, and Guangzhou. In this study, an Aerodyne Aerosol Chemical Speciation Monitor was deployed in Baoji, a middle size inland city in northwest China from 26 February to 27 March 2014. The non-refractory submicron aerosol (NR-PM1) was dominated by organics (55%), followed by sulfate (16%), nitrate (15%), ammonium (11%) and chloride (3%). A source apportionment of the organic aerosol (OA) was performed with the Sofi (Source Finder) interface of ME-2 (Multilinear Engine), and six main sources/factors were identified and classified as hydrocarbon-like OA (HOA), cooking OA (COA), biomass burning OA (BBOA), coal combustion OA (CCOA), less oxidized oxygenated OA (LO-OOA) and more oxidized oxygenated OA (MO-OOA), which contributed 20%, 14%, 13%, 9%, 23% and 21% of total OA, respectively. The contribution of secondary components shows increasing trends from clean days to polluted days, indicating the importance of secondary aerosol formation processes in driving particulate air pollution. The formation of LO-OOA and MO-OOA is mainly driven by photochemical reactions, but significantly influenced by aqueous-phase chemistry during periods of low atmospheric oxidative capacity.

46 CFR 153.530 - Special requirements for alkylene oxides.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Equipment Special Requirements § 153.530 Special requirements for alkylene oxides. When Table 1 refers to... materials, and gasket materials. (3) Materials containing oxides of magnesium, such as mineral wools. (e... this section must have continuous monitoring of oxygen concentration or have an arrangement to enable...

Effects of computer monitor-emitted radiation on oxidant/antioxidant balance in cornea and lens from rats

PubMed Central

Namuslu, Mehmet; Devrim, Erdinç; Durak, İlker

2009-01-01

Purpose This study aims to investigate the possible effects of computer monitor-emitted radiation on the oxidant/antioxidant balance in corneal and lens tissues and to observe any protective effects of vitamin C (vit C). Methods Four groups (PC monitor, PC monitor plus vitamin C, vitamin C, and control) each consisting of ten Wistar rats were studied. The study lasted for three weeks. Vitamin C was administered in oral doses of 250 mg/kg/day. The computer and computer plus vitamin C groups were exposed to computer monitors while the other groups were not. Malondialdehyde (MDA) levels and superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) activities were measured in corneal and lens tissues of the rats. Results In corneal tissue, MDA levels and CAT activity were found to increase in the computer group compared with the control group. In the computer plus vitamin C group, MDA level, SOD, and GSH-Px activities were higher and CAT activity lower than those in the computer and control groups. Regarding lens tissue, in the computer group, MDA levels and GSH-Px activity were found to increase, as compared to the control and computer plus vitamin C groups, and SOD activity was higher than that of the control group. In the computer plus vitamin C group, SOD activity was found to be higher and CAT activity to be lower than those in the control group. Conclusion The results of this study suggest that computer-monitor radiation leads to oxidative stress in the corneal and lens tissues, and that vitamin C may prevent oxidative effects in the lens. PMID:19960068

Monitoring Chemical and Biological Electron Transfer Reactions with a Fluorogenic Vitamin K Analogue Probe.

PubMed

Belzile, Mei-Ni; Godin, Robert; Durantini, Andrés M; Cosa, Gonzalo

2016-12-21

We report herein the design, synthesis, and characterization of a two-segment fluorogenic analogue of vitamin K, B-VK Q , prepared by coupling vitamin K 3 , also known as menadione (a quinone redox center), to a boron-dipyrromethene (BODIPY) fluorophore (a lipophilic reporter segment). Oxidation-reduction reactions, spectroelectrochemical studies, and enzymatic assays conducted in the presence of DT-diaphorase illustrate that the new probe shows reversible redox behavior on par with that of vitamin K, provides a high-sensitivity fluorescence signal, and is compatible with biological conditions, opening the door to monitor remotely (i.e., via imaging) redox processes in real time. In its oxidized form, B-VK Q is non-emissive, while upon reduction to the hydroquinone form, B-VK QH 2 , BODIPY fluorescence is restored, with emission quantum yield values of ca. 0.54 in toluene. Density functional theory studies validate a photoinduced electron transfer intramolecular switching mechanism, active in the non-emissive quinone form and deactivated upon reduction to the emissive dihydroquinone form. Our results highlight the potential of B-VK Q as a fluorogenic probe to study electron transfer and transport in model systems and biological structures with optimal sensitivity and desirable chemical specificity. Use of such a probe may enable a better understanding of the role that vitamin K plays in biological redox reactions ubiquitous in key cellular processes, and help elucidate the mechanism and pathological significance of these reactions in biological systems.

[Periodonta disease in smokers, and the parameters of oxidative stress].

PubMed

Golusińska-Kardach, Ewelina; Napierała, Marta; Sokalski, Jerzy; Kardachi, Hubert; Florek, Ewa

2015-01-01

Periodontal disease, periodontitis, and caries disease, are the two most common disease occurring in the mouth. They affect a large proportion of the world's population. The causes of periodontitis are varied, but the largest group are those caused by infections. The characteristic long asymptomatic period of development of periodontitis, make that patients are not aware of their condition. In-addition, it was observed that tobacco abuse affects the growth of disease and advancing disease state for periodontal diseases. Free radicals and other reactive particles are capable of destroying many cellular structures. They are produced mostly during the breathing process and the immune response or come from the environment. The evolution of living organisms ensure the proper tools to fight against reactive oxygen species after enzymatic and non-enzymatic by antioxidants. Sometimes this protection is not sufficient and the balance between antioxidants and oxidants is compromised. This condition is called oxidative stress. A number of studies looking for a link between oxidative stress, and diseases affecting human and determined that it is an important risk factor in many diseases. Evaluating the parameters of oxidative stress in the saliva allows for effective monitoring of disease progression, evaluation of the therapy and taking preventive measures in a timely manner.

Growth of ammonia-oxidizing archaea and bacteria in cattle manure compost under various temperatures and ammonia concentrations.

PubMed

Oishi, Ryu; Tada, Chika; Asano, Ryoki; Yamamoto, Nozomi; Suyama, Yoshihisa; Nakai, Yutaka

2012-05-01

A recent study showed that ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) coexist in the process of cattle manure composting. To investigate their physiological characteristics, liquid cultures seeded with fermenting cattle manure compost were incubated at various temperatures (37°C, 46°C, or 60°C) and ammonium concentrations (0.5, 1, 4, or 10 mM NH (4) (+) -N). The growth rates of the AOB and AOA were monitored using real-time polymerase chain reaction analysis targeting the bacterial and archaeal ammonia monooxygenase subunit A genes. AOB grew at 37°C and 4 or 10 mM NH (4) (+) -N, whereas AOA grew at 46°C and 10 mM NH (4) (+) -N. Incubation with allylthiourea indicated that the AOB and AOA grew by oxidizing ammonia. Denaturing gradient gel electrophoresis and subsequent sequencing analyses revealed that a bacterium related to Nitrosomonas halophila and an archaeon related to Candidatus Nitrososphaera gargensis were the predominant AOB and AOA, respectively, in the seed compost and in cultures after incubation. This is the first report to demonstrate that the predominant AOA in cattle manure compost can grow and can probably oxidize ammonia under moderately thermophilic conditions.

Oligomerization of glycine and alanine catalyzed by iron oxides: implications for prebiotic chemistry.

PubMed

Shanker, Uma; Bhushan, Brij; Bhattacharjee, G; Kamaluddin

2012-02-01

Iron oxide minerals are probable constituents of the sediments present in geothermal regions of the primitive earth. They might have adsorbed different organic monomers (amino acids, nucleotides etc.) and catalyzed polymerization processes leading to the formation of the first living cell. In the present work we tested the catalytic activity of three forms of iron oxides (Goethite, Akaganeite and Hematite) in the intermolecular condensation of each of the amino acids glycine and L-alanine. The effect of zinc oxide and titanium dioxide on the oligomerization has also been studied. Oligomerization studies were performed for 35 days at three different temperatures 50, 90 and 120°C without applying drying/wetting cycling. The products formed were characterized by HPLC and ESI-MS techniques. All three forms of iron oxides catalyzed peptide bond formation (23.2% of gly2 and 10.65% of ala2). The reaction was monitored every 7 days. Formation of peptides was observed to start after 7 days at 50°C. Maximum yield of peptides was found after 35 days at 90°C. Reaction at 120°C favors formation of diketopiperazine derivatives. It is also important to note that after 35 days of reaction, goethite produced dimer and trimer with the highest yield among the oxides tested. We suggest that the activity of goethite could probably be due to its high surface area and surface acidity.

Organs of BALB/c mice can be injured in course of tularemia.

PubMed

Pavlis, Oto; Kusakova, Eva; Novotny, Ladislav; Pohanka, Miroslav

2014-12-01

Francisella tularensis is a biological agent exploitable for bioterrorism and biological warfare purposes due to serious pathogenic progression and easy dissemination. Despite intensive research in the past, some adverse consequences remain unclear. One consequence of this pathogen is oxidative stress. The aim of this study was to undertake ex vivo assays for monitoring the disease in mice and increase our knowledge of the oxidative stress induced by tularemia. The mouse BALB/c model was chosen and the animals were infected by a dose 10(4) CFU of F. tularensis. After five days, the animals were euthanized. Blood immediately processed in plasma, spleen and liver were sampled from the cadavers. Oxidative stress markers, cytokines and histopathological were undertaken. There was a significant link between oxidative stress and tularemia. Particularly elevated levels of malondialdehyde and decreased levels of low molecular weight antioxidants were found in the liver and spleen of tularemia-infected animals. The histopathological findings correlated well with the oxidative stress markers. The liver and spleen were proven to be significantly at risk from the disease and an association between stress and neutrophils in the affected organs was found. The histopathology excluded risk to other organs such as the kidney and or heart. Oxidative stress plays a significant role in tularemia infection in mice and this was confirmed by the histology.

Biomarker analysis of liver cells exposed to surfactant-wrapped and oxidized multi-walled carbon nanotubes (MWCNTs).

PubMed

Henderson, W Matthew; Bouchard, Dermont; Chang, Xiaojun; Al-Abed, Souhail R; Teng, Quincy

2016-09-15

Carbon nanotubes (CNTs) have great potential in industrial, consumer, and mechanical applications, based partly on their unique structural, optical and electronic properties. CNTs are commonly oxidized or treated with surfactants to facilitate aqueous solution processing, and these CNT surface modifications also increase possible human and ecological exposures to nanoparticle-contaminated waters. To determine the exposure outcomes of oxidized and surfactant-wrapped multiwalled carbon nanotubes (MWCNTs) on biochemical processes, metabolomics-based profiling of human liver cells (C3A) was utilized. Cells were exposed to 0, 10, or 100ng/mL of MWCNTs for 24 and 48h; MWCNT particle size distribution, charge, and aggregation were monitored concurrently during exposures. Following MWCNT exposure, cellular metabolites were extracted, lyophilized, and buffered for (1)H NMR analysis. Acquired spectra were subjected to both multivariate and univariate analysis to determine the consequences of nanotube exposure on the metabolite profile of C3A cells. Resulting scores plots illustrated temporal and dose-dependent metabolite responses to all MWCNTs tested. Loadings plots coupled with t-test filtered spectra identified metabolites of interest. XPS analysis revealed the presence of hydroxyl and carboxyl functionalities on both MWCNTs surfaces. Metal content analysis by ICP-AES indicated that the total mass concentration of the potentially toxic impurities in the exposure experiments were extremely low (i.e. [Ni]≤2×10(-10)g/mL). Preliminary data suggested that MWCNT exposure causes perturbations in biochemical processes involved in cellular oxidation as well as fluxes in amino acid metabolism and fatty acid synthesis. Dose-response trajectories were apparent and spectral peaks related to both dose and MWCNT dispersion methodologies were determined. Correlations of the significant changes in metabolites will help to identify potential biomarkers associated with carbonaceous nanoparticle exposure. Published by Elsevier B.V.

Plasmonic transparent conducting metal oxide nanoparticles and films for optical sensing applications

DOEpatents

Ohodnicki, Jr., Paul R; Wang, Congjun; Andio, Mark A

2014-01-28

The disclosure relates to a method of detecting a change in a chemical composition by contacting a doped oxide material with a monitored stream, illuminating the doped oxide material with incident light, collecting exiting light, monitoring an optical signal based on a comparison of the incident light and the exiting light, and detecting a shift in the optical signal. The doped metal oxide has a carrier concentration of at least 10.sup.18/cm.sup.3, a bandgap of at least 2 eV, and an electronic conductivity of at least 10.sup.1 S/cm, where parameters are specified at a temperature of 25.degree. C. The optical response of the doped oxide materials results from the high carrier concentration of the doped metal oxide, and the resulting impact of changing gas atmospheres on that relatively high carrier concentration. These changes in effective carrier densities of conducting metal oxide nanoparticles are postulated to be responsible for the change in measured optical absorption associated with free carriers. Exemplary doped metal oxides include but are not limited to Al-doped ZnO, Sn-doped In.sub.2O.sub.3, Nb-doped TiO.sub.2, and F-doped SnO.sub.2.

Incubation of human sperm with micelles made from glycerophospholipid mixtures increases sperm motility and resistance to oxidative stress

PubMed Central

Costa, Carlos; Bassaizteguy, Verónica; Cardozo, Romina; Montes, José; Settineri, Robert; Nicolson, Garth L.

2018-01-01

Membrane integrity is essential in maintaining sperm viability, signaling, and motility, which are essential for fertilization. Sperm are highly susceptible to oxidative stress, as they are rich in sensitive polyunsaturated fatty acids (PUFA), and are unable to synthesize and repair many essential membrane constituents. Because of this, sperm cellular membranes are important targets of this process. Membrane Lipid Replacement (MLR) with glycerophospholipid mixtures (GPL) has been shown to ameliorate oxidative stress in cells, restore their cellular membranes, and prevent loss of function. Therefore, we tested the effects of MLR on sperm by tracking and monitoring GPL incorporation into their membrane systems and studying their effects on sperm motility and viability under different experimental conditions. Incubation of sperm with mixtures of exogenous, unoxidized GPL results in their incorporation into sperm membranes, as shown by the use of fluorescent dyes attached to GPL. The percent overall (total) sperm motility was increased from 52±2.5% to 68±1.34% after adding GPL to the incubation media, and overall sperm motility was recovered from 7±2% after H2O2 treatment to 58±2.5%)(n = 8, p<0.01) by the incorporation of GPL into sperm membranes. When sperm were exposed to H2O2, the mitochondrial inner membrane potential (MIMP), monitored using the MIMP tracker dye JC-1 in flow cytometry, diminished, whereas the addition of GPL prevented the decrease in MIMP. Confocal microscopy with Rhodamine-123 and JC-1 confirmed the mitochondrial localization of the dyes. We conclude that incubation of human sperm with glycerolphospholipids into the membranes of sperm improves sperm viability, motility, and resistance to oxidizing agents like H2O2. This suggests that human sperm might be useful to test innovative new treatments like MLR, since such treatments could improve fertility when it is adversely affected by increased oxidative stress. PMID:29856778

Evaluating fluorescence spectroscopy as a tool to characterize cyanobacteria intracellular organic matter upon simulated release and oxidation in natural water.

PubMed

Korak, Julie A; Wert, Eric C; Rosario-Ortiz, Fernando L

2015-01-01

Intracellular organic matter (IOM) from cyanobacteria may be released into natural waters following cell death in aquatic ecosystems and during oxidation processes in drinking water treatment plants. Fluorescence spectroscopy was evaluated to identify the presence of IOM from three cyanobacteria species during simulated release into natural water and following oxidation processes (i.e. ozone, free chlorine, chloramine, chlorine dioxide). Peak picking and the fluorescence index (FI) were explored to determine which IOM components (e.g., pigments) provide unique and persistent fluorescence signatures with minimal interferences from the background dissolved organic matter (DOM) found in Colorado River water (CRW). When IOM was added to ultrapure water, the fluorescence signature of the three cyanobacteria species showed similarities to each other. Each IOM exhibited a strong protein-like fluorescence and fluorescence at Ex 370 nm and Em 460 nm (FDOM), where commercial fluorescence sensors monitor. All species also had strong phycobiliprotein fluorescence (i.e. phycocyanin or phycoerythrin) in the higher excitation range (500-650 nm). All three IOM isolates had FI values greater than 2. When IOM was added to CRW, phycobiliprotein fluorescence was quenched through interactions between IOM and CRW-DOM. Mixing IOM and CRW demonstrated that protein-like and FDOM intensity responses were not a simple superposition of the starting material intensities, indicating that interactions between IOM and CRW-DOM fluorescing moieties were important. Fluorescence intensity in all regions decreased with exposure to ozone, free chlorine, and chlorine dioxide, but the FI still indicated compositional differences compared to CRW-DOM. The phycobiliproteins in IOM are not promising as a surrogate for IOM release, because their fluorescence intensity is quenched by interactions with DOM and decreased during oxidation processes. Increases in both FDOM intensity and FI are viable qualitative indicators of IOM release in natural waters and following oxidation and may provide a more robust real-time indication of the presence of IOM than conventional dissolved organic carbon or UV absorbance measurements.

Solid solutions of gadolinium doped zinc oxide nanorods by combined microwave-ultrasonic irradiation assisted crystallization

NASA Astrophysics Data System (ADS)

Kiani, Armin; Dastafkan, Kamran; Obeydavi, Ali; Rahimi, Mohammad

2017-12-01

Nanocrystalline solid solutions consisting of un-doped and gadolinium doped zinc oxide nanorods were fabricated by a modified sol-gel process utilizing combined ultrasonic-microwave irradiations. Polyvinylpyrrolidone, diethylene glycol, and triethylenetetramine respectively as capping, structure directing, and complexing agents were used under ultrasound dynamic aging and microwave heating to obtain crystalline nanorods. Crystalline phase monitoring, lattice parameters and variation, morphology and shape, elemental analysis, functional groups, reducibility, and the oxidation state of emerged species were examined by PXRD, FESEM, TEM, EDX, FTIR, micro Raman, H2-TPR, and EPR techniques. Results have verified that irradiation mechanism of gelation and crystallization reduces the reaction time, augments the crystal quality, and formation of hexagonal close pack structure of Wurtzite morphology. Besides, dissolution of gadolinium within host lattice involves lattice deformation, unit cell distortion, and angular position variation. Structure related shape and growth along with compositional purity were observed through microscopic and spectroscopic surveys. Furthermore, TPR and EPR studies elucidated more detailed behavior upon exposure to the exerted irradiations and subsequent air-annealing including the formed oxidation states and electron trapping centers, presence of gadolinium, zinc, and oxygen disarrays and defects, as well as alteration in the host unit cell via gadolinium addition.

CO2 Sensors Based on Nanocrystalline SnO2 Doped with CuO

NASA Technical Reports Server (NTRS)

Xu, Jennifer C.; Hunter, Gary W.; Liu, Chung Chiun; Ward, Benjamin J.

2008-01-01

Nanocrystalline tin oxide (SnO2) doped with copper oxide (CuO) has been found to be useful as an electrical-resistance sensory material for measuring the concentration of carbon dioxide in air. SnO2 is an n-type semiconductor that has been widely used as a sensing material for detecting such reducing gases as carbon monoxide, some of the nitrogen oxides, and hydrocarbons. Without doping, SnO2 usually does not respond to carbon dioxide and other stable gases. The discovery that the electrical resistance of CuO-doped SnO2 varies significantly with the concentration of CO2 creates opportunities for the development of relatively inexpensive CO2 sensors for detecting fires and monitoring atmospheric conditions. This discovery could also lead to research that could alter fundamental knowledge of SnO2 as a sensing material, perhaps leading to the development of SnO2-based sensing materials for measuring concentrations of oxidizing gases. Prototype CO2 sensors based on CuO-doped SnO2 have been fabricated by means of semiconductor-microfabrication and sol-gel nanomaterial-synthesis batch processes that are amendable to inexpensive implementation in mass production.

Analyzer for measurement of nitrogen oxide concentration by ozone content reduction in gas using solid state chemiluminescent sensor

NASA Astrophysics Data System (ADS)

Chelibanov, V. P.; Ishanin, G. G.; Isaev, L. N.

2014-05-01

Role of nitrogen oxide in ambient air is described and analyzed. New method of nitrogen oxide concentration measurement in gas phase is suggested based on ozone concentration measurement with titration by nitrogen oxide. Research of chemiluminescent sensor composition is carried out on experimental stand. The sensor produced on the base of solid state non-activated chemiluminescent composition is applied as ozone sensor. Composition is put on the surface of polymer matrix with developed surface. Sensor compositions includes gallic acid with addition of rodamine-6G. Model of interaction process between sensor composition and ozone has been developed, main products appeared during reaction are identified. The product determining the speed of luminescense appearance is found. This product belongs to quinone class. Then new structure of chemiluminescent composition was suggested, with absence of activation period and with high stability of operation. Experimental model of gas analyzer was constructed and operation algorithm was developed. It was demonstrated that developed NO measuring instrument would be applied for monitoring purposes of ambient air. This work was partially financially supported by Government of Russian Federation, Grant 074-U01

Characteristics of greenhouse gas emission in three full-scale wastewater treatment processes.

PubMed

Yan, Xu; Li, Lin; Liu, Junxin

2014-02-01

Three full-scale wastewater treatment processes, Orbal oxidation ditch, anoxic/anaerobic/aerobic (reversed A2O) and anaerobic/anoxic/aerobic (A2O), were selected to investigate the emission characteristics of greenhouse gases (GHG), including carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). Results showed that although the processes were different, the units presenting high GHG emission fluxes were remarkably similar, namely the highest CO2 and N2O emission fluxes occurred in the aerobic areas, and the highest CH4 emission fluxes occurred in the grit tanks. The GHG emission amount of each unit can be calculated from its area and GHG emission flux. The calculation results revealed that the maximum emission amounts of CO2, CH4 and N2O in the three wastewater treatment processes appeared in the aerobic areas in all cases. Theoretically, CH4 should be produced in anaerobic conditions, rather than aerobic conditions. However, results in this study showed that the CH4 emission fluxes in the forepart of the aerobic area were distinctly higher than in the anaerobic area. The situation for N2O was similar to that of CH4: the N2O emission flux in the aerobic area was also higher than that in the anoxic area. Through analysis of the GHG mass balance, it was found that the flow of dissolved GHG in the wastewater treatment processes and aerators may be the main reason for this phenomenon. Based on the monitoring and calculation results, GHG emission factors for the three wastewater treatment processes were determined. The A2O process had the highest CO2 emission factor of 319.3 g CO2/kg COD(removed), and the highest CH4 and N2O emission factors of 3.3 g CH4/kg COD(removed) and 3.6 g N2O/kg TN(removed) were observed in the Orbal oxidation ditch process.

Regime Shift and Microbial Dynamics in a Sequencing Batch Reactor for Nitrification and Anammox Treatment of Urine ▿†

PubMed Central

Bürgmann, Helmut; Jenni, Sarina; Vazquez, Francisco; Udert, Kai M.

2011-01-01

The microbial population and physicochemical process parameters of a sequencing batch reactor for nitrogen removal from urine were monitored over a 1.5-year period. Microbial community fingerprinting (automated ribosomal intergenic spacer analysis), 16S rRNA gene sequencing, and quantitative PCR on nitrogen cycle functional groups were used to characterize the microbial population. The reactor combined nitrification (ammonium oxidation)/anammox with organoheterotrophic denitrification. The nitrogen elimination rate initially increased by 400%, followed by an extended period of performance degradation. This phase was characterized by accumulation of nitrite and nitrous oxide, reduced anammox activity, and a different but stable microbial community. Outwashing of anammox bacteria or their inhibition by oxygen or nitrite was insufficient to explain reactor behavior. Multiple lines of evidence, e.g., regime-shift analysis of chemical and physical parameters and cluster and ordination analysis of the microbial community, indicated that the system had experienced a rapid transition to a new stable state that led to the observed inferior process rates. The events in the reactor can thus be interpreted to be an ecological regime shift. Constrained ordination indicated that the pH set point controlling cycle duration, temperature, airflow rate, and the release of nitric and nitrous oxides controlled the primarily heterotrophic microbial community. We show that by combining chemical and physical measurements, microbial community analysis and ecological theory allowed extraction of useful information about the causes and dynamics of the observed process instability. PMID:21724875

Assembly and Succession of Iron Oxide Microbial Mat Communities in Acidic Geothermal Springs

DOE PAGES

Beam, Jacob P.; Bernstein, Hans C.; Jay, Zackary J.; ...

2016-02-15

Biomineralized ferric oxide microbial mats are ubiquitous features on Earth, are common in hot springs of Yellowstone National Park (YNP, WY, USA), and form due to direct interaction between microbial and physicochemical processes. The overall goal of this study was to determine the contribution of different community members to the assembly and succession of acidic high-temperature Fe(III)-oxide mat ecosystems. Spatial and temporal changes in Fe(III)-oxide accretion and the abundance of relevant community members were monitored over 70 days using sterile glass microscope slides incubated in the outflow channels of two acidic geothermal springs (pH = 3-3.5; temperature = 68-75°C) inmore » YNP. Hydrogenobaculum spp. were the most abundant taxon identified during early successional stages (4-40 days), and have been shown to oxidize arsenite, sulfide, and hydrogen coupled to oxygen reduction. Iron-oxidizing populations of Metallosphaera yellowstonensis were detected within 4 days, and reached steady-state levels within 14-30 days, corresponding to visible Fe(III)-oxide accretion. Heterotrophic archaea colonized near 30 days, and emerged as the dominant functional guild after 70 days and in mature Fe(III)-oxide mats (1-2 cm thick). First-order rate constants of Fe(III)-oxide accretion ranged from 0.046 to 0.05 day -1 , and in situ microelectrode measurements showed that the oxidation of Fe(II) is limited by the diffusion of O2 into the Fe(III)-oxide mat. The formation of microterracettes also implicated O2 as a major variable controlling microbial growth and subsequent mat morphology. The assembly and succession of Fe(III)-oxide mat communities follows a repeatable pattern of colonization by lithoautotrophic organisms, and the subsequent growth of diverse organoheterotrophs. The unique geochemical signatures and micromorphology of extant biomineralized Fe(III)-oxide mats are also useful for understanding other Fe(II)-oxidizing systems.« less

Assembly and Succession of Iron Oxide Microbial Mat Communities in Acidic Geothermal Springs

PubMed Central

Beam, Jacob P.; Bernstein, Hans C.; Jay, Zackary J.; Kozubal, Mark A.; Jennings, Ryan deM.; Tringe, Susannah G.; Inskeep, William P.

2016-01-01

Biomineralized ferric oxide microbial mats are ubiquitous features on Earth, are common in hot springs of Yellowstone National Park (YNP, WY, USA), and form due to direct interaction between microbial and physicochemical processes. The overall goal of this study was to determine the contribution of different community members to the assembly and succession of acidic high-temperature Fe(III)-oxide mat ecosystems. Spatial and temporal changes in Fe(III)-oxide accretion and the abundance of relevant community members were monitored over 70 days using sterile glass microscope slides incubated in the outflow channels of two acidic geothermal springs (pH = 3–3.5; temperature = 68–75°C) in YNP. Hydrogenobaculum spp. were the most abundant taxon identified during early successional stages (4–40 days), and have been shown to oxidize arsenite, sulfide, and hydrogen coupled to oxygen reduction. Iron-oxidizing populations of Metallosphaera yellowstonensis were detected within 4 days, and reached steady-state levels within 14–30 days, corresponding to visible Fe(III)-oxide accretion. Heterotrophic archaea colonized near 30 days, and emerged as the dominant functional guild after 70 days and in mature Fe(III)-oxide mats (1–2 cm thick). First-order rate constants of Fe(III)-oxide accretion ranged from 0.046 to 0.05 day−1, and in situ microelectrode measurements showed that the oxidation of Fe(II) is limited by the diffusion of O2 into the Fe(III)-oxide mat. The formation of microterracettes also implicated O2 as a major variable controlling microbial growth and subsequent mat morphology. The assembly and succession of Fe(III)-oxide mat communities follows a repeatable pattern of colonization by lithoautotrophic organisms, and the subsequent growth of diverse organoheterotrophs. The unique geochemical signatures and micromorphology of extant biomineralized Fe(III)-oxide mats are also useful for understanding other Fe(II)-oxidizing systems. PMID:26913020

Assembly and Succession of Iron Oxide Microbial Mat Communities in Acidic Geothermal Springs.

PubMed

Beam, Jacob P; Bernstein, Hans C; Jay, Zackary J; Kozubal, Mark A; Jennings, Ryan deM; Tringe, Susannah G; Inskeep, William P

2016-01-01

Biomineralized ferric oxide microbial mats are ubiquitous features on Earth, are common in hot springs of Yellowstone National Park (YNP, WY, USA), and form due to direct interaction between microbial and physicochemical processes. The overall goal of this study was to determine the contribution of different community members to the assembly and succession of acidic high-temperature Fe(III)-oxide mat ecosystems. Spatial and temporal changes in Fe(III)-oxide accretion and the abundance of relevant community members were monitored over 70 days using sterile glass microscope slides incubated in the outflow channels of two acidic geothermal springs (pH = 3-3.5; temperature = 68-75°C) in YNP. Hydrogenobaculum spp. were the most abundant taxon identified during early successional stages (4-40 days), and have been shown to oxidize arsenite, sulfide, and hydrogen coupled to oxygen reduction. Iron-oxidizing populations of Metallosphaera yellowstonensis were detected within 4 days, and reached steady-state levels within 14-30 days, corresponding to visible Fe(III)-oxide accretion. Heterotrophic archaea colonized near 30 days, and emerged as the dominant functional guild after 70 days and in mature Fe(III)-oxide mats (1-2 cm thick). First-order rate constants of Fe(III)-oxide accretion ranged from 0.046 to 0.05 day(-1), and in situ microelectrode measurements showed that the oxidation of Fe(II) is limited by the diffusion of O2 into the Fe(III)-oxide mat. The formation of microterracettes also implicated O2 as a major variable controlling microbial growth and subsequent mat morphology. The assembly and succession of Fe(III)-oxide mat communities follows a repeatable pattern of colonization by lithoautotrophic organisms, and the subsequent growth of diverse organoheterotrophs. The unique geochemical signatures and micromorphology of extant biomineralized Fe(III)-oxide mats are also useful for understanding other Fe(II)-oxidizing systems.

Enhanced monitoring of hazardous waste site remediation: Electrical conductivity tomography and citizen monitoring of remediation through the EPA's community advisory group program

NASA Astrophysics Data System (ADS)

Hort, Ryan D.

In situ chemical oxidation using permanganate has become a common method for degrading trichloroethene (TCE) in contaminated aquifers. Its effectiveness, however, is dependent upon contact between the oxidant and contaminant. Monitoring permanganate movement after injection is often hampered by aquifer heterogeneity and insufficient well coverage. Time lapse electrical conductivity tomography increases the spatial extent of monitoring beyond well locations. This technique can create two- or three-dimensional images of the electrical conductivity within the aquifer to monitor aquifer chemistry changes caused by permanganate injection and oxidation reactions. In-phase and quadrature electrical conductivity were measured in homogeneous aqueous and porous media samples to determine the effects of TCE and humate oxidation by permanganate on both measures of conductivity. Further effects of clean sand, 10% kaolinite (v/v), and 10% smectite (v/v) on both types of conductivity were studied as well. Finally, in-phase electrical conductivity was measured over time after injecting permanganate solution into two-dimensional tanks containing artificial groundwater with and without TCE to observe the movement of the permanganate plume and its interaction with TCE and to examine the effectiveness of time-lapse conductivity tomography for monitoring the plume's movement. In-phase electrical conductivity after oxidation reactions involving permanganate, TCE, and humate could be accurately modeled in homogeneous batch samples. Use of forward modeling of in-phase conductivity from permanganate concentrations may be useful for improving recovery of conductivity values during survey inversion, but further work is needed combining the chemistry modeling with solute transport models. Small pH-related quadrature conductivity decreases were observed after TCE oxidation, and large quadrature conductivity increases were observed as a result of sodium ion addition; however, quadrature conductivity could not be related to concentrations of permanganate or reaction products. Additionally, EPA Superfund sites participating in the Community Advisory Group (CAG) program were examined to determine how communities may have benefitted from the program. While CAG participation was correlated with slower achievement of EPA cleanup milestones, many CAGs successfully achieved five standardized social goals. CAGs that achieved these social goals varied in composition but were similar in their focus on community outreach and ability to extend their influence beyond CAG meetings.

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

Pawlowski, L.; Lacy, W.J.; Dlugosz, J.J.

This book contains the Proceedings from an International Conference on Chemistry for the Protection of the Environment held in Lublin, Poland, September 4-7, 1989. It opens with a tribute to Andre Van Haute who was a member of the Committee on the title subject and who died in 1989. This is followed by a preface by the editors and 70 chapters, which are grouped under the following headings: General Problems; Monitoring Methods for Surface and Ground water and Analysis of Pollutants; Pathways of Chemicals in the Environment; Physicochemical Treatment: Ion Exchange; Physicochemical Treatment: Coagulation, Flocculation and Sorption; Physicochemical Treatment: Oxidation-Reductionmore » Processes; Physicochemical Treatment; Membrane Processes; and Miscellaneous Methods for Removal of Pollutants. There is a brief subject index.« less

Oxidant activity in hyperarid soils from Atacama Desert in southern Peru, under conditions of the labeled release and thermal evolved gas analysis experiments: Implications for the search of organic matter on Mars

NASA Astrophysics Data System (ADS)

Valdivia-Silva, Julio E.; Navarro-Gonzalez, Rafael; McKay, Chris

Thermal evolved gas analysis (TEGA), one of several instruments on board of the Phoenix Lander, is a combination of a high temperature furnace and a mass spectrometer that was used to analyze Mars soil samples heated at a programmed ramp rate up to 1000 ° C. The evolved gases generated during the process were analyzed with the evolved gas analyzer (a mass spectrometer) in order to determine the composition of gases released as a function of temperature. In other hand, labeled release experiment (LR), one of the Viking biology anal-ysis used on Mars, monitored the radioactive gas evolution after the addition of a 14C-labeled aqueous organic substrate into a sealed test cell that contained a Martian surface sample. This experiment was designed to test Martian surface samples for the presence of life by measuring metabolic activity and distinguishing it from physical or chemical activity. The interpretation of the Viking LR experiment was that the tested soils were chemically reactive and not biolog-ically active, and that at least two oxidative processes with different kinetics were required to explain the observed decomposition of organics, while TEGA experiment of the Phoenix mis-sion apparently didn't detect organic matter on the surface of Mars. Both of these experiments showed little possibility of the presence of organics, and therefore the presence of life. Here we examine the evolved gas properties of hyperarid soils from the Pampas de La Joya, which is considered as a new analogue to Mars, in order to investigate the effect of the soil matrix on the TEGA response, and additionally, we conducted experiments under Viking LR protocol to test the decomposition kinetics of organic compounds in aqueous solution added to these soils. Our TEGA results indicate that native or added organics present in these samples were oxidized to CO2 during thermal process, suggesting the existence in these soils of a thermolabile oxidant which is highly oxidative and other thermostable oxidant which has a minor oxidative activity and that survives the heat-treatment. Interestingly, LR experiment shows that the 13C-labeled formate and DL-alanine were oxidized to 13CO2 when added in aqueous solution to soils collected from the Pampas de La Joya region. The observation of similar 13CO2 initial releasing by soils treated with L-alanine, compared to soils treated D-alanine, indicates the presence of one or more nonbiological chemical decomposition mechanisms similar to Yungay soils and the Viking LR experiment. Thus, the soils from Pampas of La Joya, are potentially excellent analogues of the oxidative processes that occur on Mars, and can be used to study mechanisms of destruction of organics on this planet. The nature of oxidant(s) present in the soils from Pampas de La Joya is still unknown.

Particle Simulation of Oxidation Induced Band 3 Clustering in Human Erythrocytes

PubMed Central

Shimo, Hanae; Arjunan, Satya Nanda Vel; Machiyama, Hiroaki; Nishino, Taiko; Suematsu, Makoto; Fujita, Hideaki; Tomita, Masaru; Takahashi, Koichi

2015-01-01

Oxidative stress mediated clustering of membrane protein band 3 plays an essential role in the clearance of damaged and aged red blood cells (RBCs) from the circulation. While a number of previous experimental studies have observed changes in band 3 distribution after oxidative treatment, the details of how these clusters are formed and how their properties change under different conditions have remained poorly understood. To address these issues, a framework that enables the simultaneous monitoring of the temporal and spatial changes following oxidation is needed. In this study, we established a novel simulation strategy that incorporates deterministic and stochastic reactions with particle reaction-diffusion processes, to model band 3 cluster formation at single molecule resolution. By integrating a kinetic model of RBC antioxidant metabolism with a model of band 3 diffusion, we developed a model that reproduces the time-dependent changes of glutathione and clustered band 3 levels, as well as band 3 distribution during oxidative treatment, observed in prior studies. We predicted that cluster formation is largely dependent on fast reverse reaction rates, strong affinity between clustering molecules, and irreversible hemichrome binding. We further predicted that under repeated oxidative perturbations, clusters tended to progressively grow and shift towards an irreversible state. Application of our model to simulate oxidation in RBCs with cytoskeletal deficiency also suggested that oxidation leads to more enhanced clustering compared to healthy RBCs. Taken together, our model enables the prediction of band 3 spatio-temporal profiles under various situations, thus providing valuable insights to potentially aid understanding mechanisms for removing senescent and premature RBCs. PMID:26046580

Particle Simulation of Oxidation Induced Band 3 Clustering in Human Erythrocytes.

PubMed

Shimo, Hanae; Arjunan, Satya Nanda Vel; Machiyama, Hiroaki; Nishino, Taiko; Suematsu, Makoto; Fujita, Hideaki; Tomita, Masaru; Takahashi, Koichi

2015-06-01

Oxidative stress mediated clustering of membrane protein band 3 plays an essential role in the clearance of damaged and aged red blood cells (RBCs) from the circulation. While a number of previous experimental studies have observed changes in band 3 distribution after oxidative treatment, the details of how these clusters are formed and how their properties change under different conditions have remained poorly understood. To address these issues, a framework that enables the simultaneous monitoring of the temporal and spatial changes following oxidation is needed. In this study, we established a novel simulation strategy that incorporates deterministic and stochastic reactions with particle reaction-diffusion processes, to model band 3 cluster formation at single molecule resolution. By integrating a kinetic model of RBC antioxidant metabolism with a model of band 3 diffusion, we developed a model that reproduces the time-dependent changes of glutathione and clustered band 3 levels, as well as band 3 distribution during oxidative treatment, observed in prior studies. We predicted that cluster formation is largely dependent on fast reverse reaction rates, strong affinity between clustering molecules, and irreversible hemichrome binding. We further predicted that under repeated oxidative perturbations, clusters tended to progressively grow and shift towards an irreversible state. Application of our model to simulate oxidation in RBCs with cytoskeletal deficiency also suggested that oxidation leads to more enhanced clustering compared to healthy RBCs. Taken together, our model enables the prediction of band 3 spatio-temporal profiles under various situations, thus providing valuable insights to potentially aid understanding mechanisms for removing senescent and premature RBCs.

Silicon Carbide-Based Hydrogen Gas Sensors for High-Temperature Applications

PubMed Central

Kim, Seongjeen; Choi, Jehoon; Jung, Minsoo; Joo, Sungjae; Kim, Sangchoel

2013-01-01

We investigated SiC-based hydrogen gas sensors with metal-insulator-semiconductor (MIS) structure for high temperature process monitoring and leak detection applications in fields such as the automotive, chemical and petroleum industries. In this work, a thin tantalum oxide (Ta2O5) layer was exploited with the purpose of sensitivity improvement, because tantalum oxide has good stability at high temperature with high permeability for hydrogen gas. Silicon carbide (SiC) was used as a substrate for high-temperature applications. We fabricated Pd/Ta2O5/SiC-based hydrogen gas sensors, and the dependence of their I-V characteristics and capacitance response properties on hydrogen concentrations were analyzed in the temperature range from room temperature to 500 °C. According to the results, our sensor shows promising performance for hydrogen gas detection at high temperatures. PMID:24113685

Potential technology transfers of research on low-temperature carbon monoxide-oxygen recombination catalysts

NASA Technical Reports Server (NTRS)

Poziomek, Edward J.

1990-01-01

Results from research on catalytic recombination of CO-O2 for stable closed-cycle operation of CO2 lasers hold much promise for a variety of technology transfer. Expansion of CO2 laser remote sensing applications toward chemical detection and pollution monitoring would certainly be expected. However, the catalysts themselves may be especially effective in low-temperature oxidation of a number of chemicals in addition to CO. It is therefore of interest to compare the CO-O2 catalysts with chemical systems designed for chemical sensing, air purification and process catalysis. Success in understanding the catalytic mechanisms of the recombination of CO-O2 could help to shed light on how catalyst systems operate. New directions in low-temperature oxidation catalysts, coatings for chemical sensors and sorbents for air purification could well emerge.

Silicon carbide-based hydrogen gas sensors for high-temperature applications.

PubMed

Kim, Seongjeen; Choi, Jehoon; Jung, Minsoo; Joo, Sungjae; Kim, Sangchoel

2013-10-09

We investigated SiC-based hydrogen gas sensors with metal-insulator-semiconductor (MIS) structure for high temperature process monitoring and leak detection applications in fields such as the automotive, chemical and petroleum industries. In this work, a thin tantalum oxide (Ta2O5) layer was exploited with the purpose of sensitivity improvement, because tantalum oxide has good stability at high temperature with high permeability for hydrogen gas. Silicon carbide (SiC) was used as a substrate for high-temperature applications. We fabricated Pd/Ta2O5/SiC-based hydrogen gas sensors, and the dependence of their I-V characteristics and capacitance response properties on hydrogen concentrations were analyzed in the temperature range from room temperature to 500 °C. According to the results, our sensor shows promising performance for hydrogen gas detection at high temperatures.

In vitro monitoring of oxidative processes with self-aggregating gold nanoparticles using all-optical photoacoustic spectroscopy.

PubMed

Yasmin, Zannatul; Khachatryan, Edward; Lee, Yuan-Hao; Maswadi, Saher; Glickman, Randolph; Nash, Kelly L

2015-02-15

In this work, the assembly of gold nanoparticles of (AuNPs) is used to detect the presence of the biomolecule glutathione (GSH) using a novel technique called "all-optical photoacoustic spectroscopy" (AOPAS). The AOPAS technique coupled with AuNPs forms the basis of a biosensing technique capable of probing the dynamic evolution of nano-bio interfaces within a microscopic volume. Dynamic Light Scattering (DLS) and ultraviolet-visible (UV-vis) spectra were measured to describe the kinetics governing the interparticle interactions by monitoring the AuNPs assembly and evolution of the surface plasmon resonance (SPR) band. A comparison of the same dynamic evolution of AuNPs assembly was performed using the AOPAS technique to confirm the validity of this method. The fundamental study is complemented by a demonstration of the performance of this biosensing technique in the presence of cell culture medium containing fetal bovine serum (FBS), which forms a protein corona on the surface of the AuNPs. This work demonstrates that the in vitro monitoring capabilities of the AOPAS provides sensitive measurement at the microscopic level and low nanoparticle concentrations without the artifacts limiting the use of conventional biosensing methods, such as fluorescent indicators. The AOPAS technique not only provides a facile approach for in vitro biosensing, but also shed a light on the real-time detection of thiol containing oxidative stress biomarkers in live systems using AuNPs. Copyright © 2014 Elsevier B.V. All rights reserved.

Nitric Oxide (NO) Measurements in Stomatal Guard Cells.

PubMed

Agurla, Srinivas; Gayatri, Gunja; Raghavendra, Agepati S

2016-01-01

The quantitative measurement of nitric oxide (NO) in plant cells acquired great importance, in view of the multifaceted function and involvement of NO as a signal in various plant processes. Monitoring of NO in guard cells is quite simple because of the large size of guard cells and ease of observing the detached epidermis under microscope. Stomatal guard cells therefore provide an excellent model system to study the components of signal transduction. The levels and functions of NO in relation to stomatal closure can be monitored, with the help of an inverted fluorescence or confocal microscope. We can measure the NO in guard cells by using flouroprobes like 4,5-diamino fluorescein diacetate (DAF-2DA). This fluorescent dye, DAF-2DA, is cell permeable and after entry into the cell, the diacetate group is removed by the cellular esterases. The resulting DAF-2 form is membrane impermeable and reacts with NO to generate the highly fluorescent triazole (DAF-2T), with excitation and emission wavelengths of 488 and 530 nm, respectively. If time-course measurements are needed, the epidermis can be adhered to a cover-glass or glass slide and left in a small petri dishes. Fluorescence can then be monitored at required time intervals; with a precaution that excitation is done minimally, only when a fluorescent image is acquired. The present method description is for the epidermis of Arabidopsis thaliana and Pisum sativum and should work with most of the other dicotyledonous plants.

In Situ Magnetic Susceptibility Variations at Two Contaminated Sites: Brandywine, MD and Bemidji, MN

NASA Astrophysics Data System (ADS)

Donaldson, Y. Y.; Kessouri, P.; Ntarlagiannis, D.; Johnson, T. C.; Day-Lewis, F. D.; Johnson, C. D.; Bekins, B. A.; Slater, L. D.

2017-12-01

Geophysical methods are widely used monitoring tools for investigating subsurface processes. Compared to more traditional methods, they are low cost and minimally invasive. Magnetic susceptibility (MS) is a geophysical technique particularly sensitive to the presence of ferri/ ferro-magnetic particles such as iron oxides (e.g., magnetite, hematite and goethite). These oxides can be formed through microbially mediated redox reactions, inducing changes in the soil properties that can be observed by MS measurements. Monitoring MS changes over time provides indications of iron mineral transformations in the ground. These transformations are of particular interest for the characterization of contaminated sites. We acquired borehole MS measurements from two contaminated sites: Brandywine, MD and Bemidji, MN. Active remediation was applied at Brandywine, whereas natural attenuation has been geophysically monitored at Bemidji since 2011 using MS log measurements. High MS values were observed at both sites within the contaminated area only. We hypothesize that this is due to iron reducing bacteria reducing Fe-(III) to Fe-(II) and utilizing contaminants and/or amendments injected as a carbon source. At Bemidji, elevated MS readings were observed in the smear zone and correlate to the presence of magnetite. Furthermore, time-lapse MS observations at Bemidji indicate a decay in signal amplitude over time suggesting further redox transformation into less magnetic particles. For both field examples presented here, we observe variations in magnetic susceptibility within the contaminated areas that can be linked with redox reactions and mineral transformations occurring during the degradation of organic contaminants.

Naproxen degradation test to monitor Trametes versicolor activity in solid-state bioremediation processes.

PubMed

Rodríguez-Rodríguez, Carlos E; Marco-Urrea, Ernest; Caminal, Gloria

2010-07-15

The white-rot fungus Trametes versicolor has been studied as a potential agent for the removal of environmental pollutants. For long-time solid-phase bioremediation systems a test is required to monitor the metabolic status of T. versicolor and its degradation capability at different stages. A biodegradation test based on the percentage of degradation of a spiked model pharmaceutical (anti-inflammatory naproxen) in 24 h (ND24) is proposed to monitor the removal of pharmaceuticals and personal care products in sewage sludge. ND24 is intended to act as a test complementary to ergosterol quantification as specific fungal biomarker, and laccase activity as extracellular oxidative capacity of T. versicolor. For samples collected over 45 d, ND24 values did not necessarily correlate with ergosterol or laccase amounts but in most cases, they were over 30% degradation, indicating that T. versicolor may be suitable for bioremediation of sewage sludge in the studied period. 2010 Elsevier B.V. All rights reserved.

Probing ground-state hole transfer between equivalent, electrochemically inaccessible states in multiporphyrin arrays using time-resolved optical spectroscopy.

PubMed

Song, Hee-eun; Taniguchi, Masahiko; Kirmaier, Christine; Bocian, David F; Lindsey, Jonathan S; Holten, Dewey

2009-01-01

A new strategy is described and implemented for determining the rates of hole-transfer between equivalent porphyrins in multiporphyrin architectures. The approach allows access to these rates between sites that are not the most easily oxidized components of the array. The specific architectures investigated with this new strategy are triads consisting of one zinc porphyrin (Zn) and two free base porphyrins (Fb). The triads employ a diphenylethyne linker (ZnFbFbU) and a phenylene linker (ZnFbFbPhi). The zinc porphyrin is selectively oxidized to produce Zn(+)FbFb, the free base porphyrins are excited to produce the excited-state mixture Zn(+)Fb*Fb and Zn(+)FbFb*, and the subsequent dynamics are monitored by ultrafast absorption spectroscopy. The system evolves by a combination of energy- and hole-transfer processes involving (adjacent and nonadjacent) zinc and free base porphyrin constituents that are complete within 100 ps of excitation; the rate constants of many of these processes are derived from prior studies of the oxidized forms of the benchmark dyads (ZnFbU and ZnFbPhi). One of the excited-state decay channels produces the metastable state ZnFbFb(+) that decays to a second metastable state ZnFb(+)Fb by the target hole-transfer process, followed by rapid hole transfer to produce the Zn(+)FbFb thermodynamic ground state of the system. The rate constant for hole transfer between the free base porphyrins in the oxidized ZnFbFb triads is found to be (0.5 ns)(-1) and (0.6 ns)(-1) across phenylene and diphenylethyne linkers, respectively. These rate constants are comparable to those recently measured, using a related but distinct strategy, for ground-state hole transfer between zinc porphyrins in oxidized ZnZnFb triads. The two complementary strategies provide unique approaches for probing hole transfer between equivalent sites in multiporphyrin arrays, with the choice of method being guided by the particular target process and the ease of synthesis of the necessary architectures.

Synthesis and integration of one-dimensional nanostructures for chemical gas sensing applications

NASA Astrophysics Data System (ADS)

Parthangal, Prahalad Madhavan

The need for improved measurement technology for the detection and monitoring of gases has increased tremendously for maintenance of domestic and industrial health and safety, environmental surveys, national security, food-processing, medical diagnostics and various other industrial applications. Among the several varieties of gas sensors available in the market, solid-state sensors are the most popular owing to their excellent sensitivity, ruggedness, versatility and low cost. Semiconducting metal oxides such as tin oxide (SnO2), zinc oxide (ZnO), and tungsten oxide (WO3) are routinely employed as active materials in these sensors. Since their performance is directly linked to the exposed surface area of the sensing material, one-dimensional nanostructures possessing very high surface to volume ratios are attractive candidates for designing the next generation of sensors. Such nano-sensors also enable miniaturization thereby reducing power consumption. The key to achieve success in one-dimensional nanotechnologies lies in assembly. While synthesis techniques and capabilities continue to expand rapidly, progress in controlled assembly has been sluggish due to numerous technical challenges. In this doctoral thesis work, synthesis and characterization of various one-dimensional nanostructures including nanotubes of SnO2, and nanowires of WO3 and ZnO, as well as their direct integration into miniature sensor platforms called microhotplates have been demonstrated. The key highlights of this research include devising elegant strategies for growing metal oxide nanotubes using carbon nanotubes as templates, substantially reducing process temperatures to enable growth of WO3 nanowires on microhotplates, and successfully fabricating a ZnO nanowire array based sensor using a hybrid nanowire-nanoparticle assembly approach. In every process, the gas-sensing properties of one-dimensional nanostructures were observed to be far superior in comparison with thin films of the same material. Essentially, we have formulated simple processes for improving current thin film sensors as well as a means of incorporating nanostructures directly into miniature sensing devices. Apart from gas sensing applications, the approaches described in this work are suitable for designing future nanoelectronic devices such as gas-ionization, capacitive and calorimetric sensors, miniature sensor arrays for electronic nose applications, field emitters, as well as photonic devices such as nanoscale LEDs and lasers.

40 CFR 63.3547 - What are the requirements for continuous parameter monitoring system installation, operation, and...

Code of Federal Regulations, 2011 CFR

2011-07-01

... section for each gas temperature monitoring device. (i) Locate the temperature sensor in a position that..., install a gas temperature monitor in the firebox of the thermal oxidizer or in the duct immediately... a gas temperature monitor according to paragraph (c)(2)(i) or (ii) of this section. (i) If you...

40 CFR 63.3547 - What are the requirements for continuous parameter monitoring system installation, operation, and...

Code of Federal Regulations, 2010 CFR

2010-07-01

... section for each gas temperature monitoring device. (i) Locate the temperature sensor in a position that..., install a gas temperature monitor in the firebox of the thermal oxidizer or in the duct immediately... a gas temperature monitor according to paragraph (c)(2)(i) or (ii) of this section. (i) If you...

Preservation of organic matter in nontronite against iron redox cycling.

NASA Astrophysics Data System (ADS)

Zeng, Q.

2015-12-01

It is generally believed that clay minerals can protect organic matter from degradation in redox active environments, but both biotic and abiotic factors can influence the redox process and thus potentially change the clay-organic associations. However, the specific mechanisms involved in this process remain poorly understood. In this study, a model organic compound, 12-Aminolauric acid (ALA) was selected to intercalate into the structural interlayer of nontronite (an iron-rich smectite, NAu-2) to form an ALA-intercalated NAu-2 composite (ALA-NAu-2). Shawanella putrefaciens CN32 and sodium dithionite were used to reduce structural Fe(III) to Fe(II) in NAu-2 and ALA-NAu-2. The bioreduced ALA-NAu-2 was subsequently re-oxidized by air. The rates and extents of bioreduction and air re-oxidation were determined with wet chemistry methods. ALA release from ALA-NAu-2 via redox process was monitored. Mineralogical changes after iron redox cycle were investigated with X-ray diffraction, infrared spectroscopy, and scanning and transmission electron microscopy. At the beginning stage of bioreduction, S. putrefaciens CN32 reduced Fe(III) from the edges of nontronite and preferentially reduced and dissolved small and poorly crystalline particles, and released ALA, resulting a positive correlation between ALA release and iron reduction extent (<12%). The subsequent bioreduction (reduction extent ranged from 12~30%) and complete air re-oxidation showed no effect on ALA release. These results suggest that released ALA was largely from small and poorly crystalline NAu-2 particles. In contrast to bioreduction, chemical reduction did not exhibit any selectivity in reducing ALA-NAu-2 particles, and a considerable amount of reductive dissolution was responsible for a large amount of ALA release (>80%). Because bacteria are the principal agent for mediating redox process in natural environments, our results demonstrated that the structural interlayer of smectite can serve as a potential shelter to protect organic matter from oxidation.

Lowering the environmental impact of high-kappa/ metal gate stack surface preparation processes

NASA Astrophysics Data System (ADS)

Zamani, Davoud

ABSTRACT Hafnium based oxides and silicates are promising high-κ dielectrics to replace SiO2 as gate material for state-of-the-art semiconductor devices. However, integrating these new high-κ materials into the existing complementary metal-oxide semiconductor (CMOS) process remains a challenge. One particular area of concern is the use of large amounts of HF during wet etching of hafnium based oxides and silicates. The patterning of thin films of these materials is accomplished by wet etching in HF solutions. The use of HF allows dissolution of hafnium as an anionic fluoride complex. Etch selectivity with respect to SiO2 is achieved by appropriately diluting the solutions and using slightly elevated temperatures. From an ESH point of view, it would be beneficial to develop methods which would lower the use of HF. The first objective of this study is to find new chemistries and developments of new wet etch methods to reduce fluoride consumption during wet etching of hafnium based high-κ materials. Another related issue with major environmental impact is the usage of large amounts of rinsing water for removal of HF in post-etch cleaning step. Both of these require a better understanding of the HF interaction with the high-κ surface during the etching, cleaning, and rinsing processes. During the rinse, the cleaning chemical is removed from the wafers. Ensuring optimal resource usage and cycle time during the rinse requires a sound understanding and quantitative description of the transport effects that dominate the removal rate of the cleaning chemicals from the surfaces. Multiple processes, such as desorption and re-adsorption, diffusion, migration and convection, all factor into the removal rate of the cleaning chemical during the rinse. Any of these processes can be the removal rate limiting process, the bottleneck of the rinse. In fact, the process limiting the removal rate generally changes as the rinse progresses, offering the opportunity to save resources. The second objective of this study is to develop new rinse methods to reduce water and energy usage during rinsing and cleaning of hafnium based high-κ materials in single wafer-cleaning tools. It is necessary to have a metrology method which can study the effect of all process parameters that affect the rinsing by knowing surface concentration of contaminants in patterned hafnium based oxides and silicate wafers. This has been achieved by the introduction of a metrology method at The University of Arizona which monitors the transport of contaminant concentrations inside micro- and nano- structures. This is the only metrology which will be able to provide surface concentration of contaminants inside hafnium based oxides and silicate micro-structures while the rinsing process is taking place. The goal of this research is to study the effect of various process parameters on rinsing of patterned hafnium based oxides and silicate wafers, and modify a metrology method for end point detection.

Cork boiling wastewater treatment and reuse through combination of advanced oxidation technologies.

PubMed

Ponce-Robles, L; Miralles-Cuevas, S; Oller, I; Agüera, A; Trinidad-Lozano, M J; Yuste, F J; Malato, S

2017-03-01

Industrial preparation of cork consists of its immersion for approximately 1 hour in boiling water. The use of herbicides and pesticides in oak tree forests leads to absorption of these compounds by cork; thus, after boiling process, they are present in wastewater. Cork boiling wastewater shows low biodegradability and high acute toxicity involving partial inhibition of their biodegradation when conventional biological treatment is applied. In this work, a treatment line strategy based on the combination of advanced physicochemical technologies is proposed. The final objective is the reuse of wastewater in the cork boiling process; thus, reducing consumption of fresh water in the industrial process itself. Coagulation pre-treatment with 0.5 g/L of FeCl 3 attained the highest turbidity elimination (86 %) and 29 % of DOC elimination. Similar DOC removal was attained when using 1 g/L of ECOTAN BIO (selected for ozonation tests), accompanied of 64 % of turbidity removal. Ozonation treatments showed less efficiency in the complete oxidation of cork boiling wastewater, compared to solar photo-Fenton process, under the studied conditions. Nanofiltration system was successfully employed as a final purification step with the aim of obtaining a high-quality reusable permeate stream. Monitoring of unknown compounds by LC-QTOF-MS allowed the qualitative evaluation of the whole process. Acute and chronic toxicity as well as biodegradability assays were performed throughout the whole proposed treatment line.

Iohexol degradation in wastewater and urine by UV-based Advanced Oxidation Processes (AOPs): Process modeling and by-products identification.

PubMed

Giannakis, Stefanos; Jovic, Milica; Gasilova, Natalia; Pastor Gelabert, Miquel; Schindelholz, Simon; Furbringer, Jean-Marie; Girault, Hubert; Pulgarin, César

2017-06-15

In this work, an Iodinated Contrast Medium (ICM), Iohexol, was subjected to treatment by 3 Advanced Oxidation Processes (AOPs) (UV, UV/H 2 O 2 , UV/H 2 O 2 /Fe 2+ ). Water, wastewater and urine were spiked with Iohexol, in order to investigate the treatment efficiency of AOPs. A tri-level approach has been deployed to assess the UV-based AOPs efficacy. The treatment was heavily influenced by the UV transmittance and the organics content of the matrix, as dilution and acidification improved the degradation but iron/H 2 O 2 increase only moderately. Furthermore, optimization of the treatment conditions, as well as modeling of the degradation was performed, by step-wise constructed quadratic or product models, and determination of the optimal operational regions was achieved through desirability functions. Finally, global chemical parameters (COD, TOC and UV-Vis absorbance) were followed in parallel with specific analyses to elucidate the degradation process of Iohexol by UV-based AOPs. Through HPLC/MS analysis the degradation pathway and the effects the operational parameters were monitored, thus attributing the pathways the respective modifications. The addition of iron in the UV/H 2 O 2 process inflicted additional pathways beneficial for both Iohexol and organics removal from the matrix. Copyright © 2016 Elsevier Ltd. All rights reserved.

Electronic structure of indium-tungsten-oxide alloys and their energy band alignment at the heterojunction to crystalline silicon

NASA Astrophysics Data System (ADS)

Menzel, Dorothee; Mews, Mathias; Rech, Bernd; Korte, Lars

2018-01-01

The electronic structure of thermally co-evaporated indium-tungsten-oxide films is investigated. The stoichiometry is varied from pure tungsten oxide to pure indium oxide, and the band alignment at the indium-tungsten-oxide/crystalline silicon heterointerface is monitored. Using in-system photoelectron spectroscopy, optical spectroscopy, and surface photovoltage measurements, we show that the work function of indium-tungsten-oxide continuously decreases from 6.3 eV for tungsten oxide to 4.3 eV for indium oxide, with a concomitant decrease in the band bending at the hetero interface to crystalline silicon than indium oxide.

Transport via SLC5A8 (SMCT1) Is Obligatory for 2-Oxothiazolidine-4-Carboxylate to Enhance Glutathione Production in Retinal Pigment Epithelial Cells

PubMed Central

Babu, Ellappan; Ananth, Sudha; Veeranan-Karmegam, Rajalakshmi; Coothankandaswamy, Veena; Smith, Sylvia B.; Boettger, Thomas; Ganapathy, Vadivel

2011-01-01

Purpose. To evaluate the role of SLC5A8 in the transport of 2-oxothiazolidine-4-carboxylate (OTC) and to determine whether OTC augments glutathione production in RPE cells, thereby providing protection against oxidative stress. Methods. SLC5A8-mediated transport of OTC was monitored in Xenopus laevis oocytes by electrophysiological means. Saturation kinetics, Na+-activation kinetics, and inhibition by ibuprofen were analyzed by monitoring OTC-induced currents as a measure of transport activity. Oxidative stress was induced in ARPE-19 cells and primary RPE cells isolated from wild type and Slc5a8-/- mouse retinas using H2O2, and the effects of OTC on cell death and intracellular glutathione concentration were examined. Results. Heterologous expression of human SLC5A8 in X. laevis oocytes induced Na+-dependent inward currents in the presence of OTC under voltage-clamp conditions. The transport of OTC via SLC5A8 was saturable, with a Kt of 104 ± 3 μM. The Na+-activation kinetics was sigmoidal with a Hill coefficient of 1.9 ± 0.1, suggesting involvement of two Na+ in the activation process. Ibuprofen, a blocker of SLC5A8, inhibited SLC5A8-mediated OTC transport; the concentration necessary for half-maximal inhibition was 17 ± 1 μM. OTC increased glutathione levels and protected ARPE-19 and primary RPE cells isolated from wild type mouse retinas from H2O2-induced cell death. These effects were abolished in primary RPE isolated from Slc5a8-/- mouse retinas. Conclusions. OTC is a transportable substrate for SLC5A8. OTC augments glutathione production in RPE cells, thereby protecting them from oxidative damage. Transport via SLC5A8 is obligatory for this process. PMID:21508099

Comparative study of gas-analyzing systems designed for continuous monitoring of TPP emissions

NASA Astrophysics Data System (ADS)

Kondrat'eva, O. E.; Roslyakov, P. V.

2017-06-01

Determining the composition of combustion products is important in terms of both control of emissions into the atmosphere from thermal power plants and optimization of fuel combustion processes in electric power plants. For this purpose, the concentration of oxygen, carbon monoxide, nitrogen, and sulfur oxides in flue gases is monitored; in case of solid fuel combustion, fly ash concentration is monitored as well. According to the new nature conservation law in Russia, all large TPPs shall be equipped with continuous emission monitoring and measurement systems (CEMMS) into the atmosphere. In order to ensure the continuous monitoring of pollutant emissions, direct round-the-clock measurements are conducted with the use of either domestically produced or imported gas analyzers and analysis systems, the operation of which is based on various physicochemical methods and which can be generally used when introducing CEMMS. Depending on the type and purposes of measurement, various kinds of instruments having different features may be used. This article represents a comparative study of gas-analysis systems for measuring the content of polluting substances in exhaust gases based on various physical and physicochemical analysis methods. It lists basic characteristics of the methods commonly applied in the area of gas analysis. It is proven that, considering the necessity of the long-term, continuous operation of gas analyzers for monitoring and measurement of pollutant emissions into the atmosphere, as well as the requirements for reliability and independence from aggressive components and temperature of the gas flow, it is preferable to use optical gas analyzers for the aforementioned purposes. In order to reduce the costs of equipment comprising a CEMMS at a TPP and optimize the combustion processes, electrochemical and thermomagnetic gas analyzers may also be used.

Hydrogen and Oxygen Gas Monitoring System Design and Operation

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

Lee C. Cadwallader; Kevin G. DeWall; J. Stephen Herring

2007-06-01

This paper describes pertinent design practices of selecting types of monitors, monitor unit placement, setpoint selection, and maintenance considerations for gas monitors. While hydrogen gas monitors and enriched oxygen atmosphere monitors as they would be needed for hydrogen production experiments are the primary focus of this paper, monitors for carbon monoxide and carbon dioxide are also discussed. The experiences of designing, installing, and calibrating gas monitors for a laboratory where experiments in support of the DOE Nuclear Hydrogen Initiative (NHI) are described along with codes, standards, and regulations for these monitors. Information from the literature about best operating practices ismore » also presented. The NHI program has two types of activities. The first, near-term activity is laboratory and pilot-plant experimentation with different processes in the kilogram per day scale to select the most promising types of processes for future applications of hydrogen production. Prudent design calls for indoor gas monitors to sense any hydrogen leaks within these laboratory rooms. The second, longer-term activity is the prototype, or large-scale plants to produce tons of hydrogen per day. These large, outdoor production plants will require area (or “fencepost”) monitoring of hydrogen gas leaks. Some processes will have oxygen production with hydrogen production, and any oxygen releases are also safety concerns since oxygen gas is the strongest oxidizer. Monitoring of these gases is important for personnel safety of both indoor and outdoor experiments. There is some guidance available about proper placement of monitors. The fixed point, stationary monitor can only function if the intruding gas contacts the monitor. Therefore, monitor placement is vital to proper monitoring of the room or area. Factors in sensor location selection include: indoor or outdoor site, the location and nature of potential vapor/gas sources, chemical and physical data of the gases or vapors, liquids with volatility need sensors near the potential sources of release, nature and concentration of gas releases, natural and mechanical ventilation, detector installation locations not vulnerable to mechanical or water damage from normal operations, and locations that lend themselves to convenient maintenance and calibration. The guidance also states that sensors should be located in all areas where hazardous accumulations of gas may occur. Such areas might not be close to release points but might be areas with restricted air movement. Heavier than air gases are likely to accumulate in pits, trenches, drains, and other low areas. Lighter than air gases are more likely to accumulate in overhead spaces, above drop ceilings, etc. In general, sensors should be located close to any potential sources of major release of gas. The paper gives data on monitor sensitivity and expected lifetimes to support the monitor selection process. Proper selection of indoor and outdoor locations for monitors is described, accounting for the vapor densities of hydrogen and oxygen. The latest information on monitor alarm setpoint selection is presented. Typically, monitors require recalibration at least every six months, or more frequently for inhospitable locations, so ready access to the monitors is an important issue to consider in monitor siting. Gas monitors, depending on their type, can be susceptible to blockages of the detector element (i.e., dus« less

Heterogeneous Oxidation of Laboratory-generated Mixed Composition and Biomass Burning Particles

NASA Astrophysics Data System (ADS)

Lim, C. Y.; Sugrue, R. A.; Hagan, D. H.; Cappa, C. D.; Kroll, J. H.; Browne, E. C.

2016-12-01

Heterogeneous oxidation of organic aerosol (OA) can significantly transform the chemical and physical properties of particulate matter in the atmosphere, leading to changes to the chemical composition of OA and potential volatilization of organic compounds. It has become increasingly apparent that the heterogeneous oxidation kinetics of OA depend on the phase and morphology of the particles. However, most laboratory experiments to date have been performed on single-component, purely organic precursors, which may exhibit fundamentally different behavior than more complex particles in the atmosphere. Here we present laboratory studies of the heterogeneous oxidation of two more complex chemical systems: thin, organic coatings on inorganic seed particles and biomass burning OA. In the first system, squalane (C30H62), a model compound for reduced OA, is coated onto dry ammonium sulfate particles at various thicknesses (10-20 nm) and exposed to hydroxyl radical (OH) in a flow tube reactor. In the second, we use a semi-batch reactor to study the heterogeneous OH-initiated oxidation of biomass burning particles as a part of the 2016 FIREX campaign in Missoula, MT. The resulting changes in chemical composition are monitored with an Aerodyne High Resolution Time-of-flight Aerosol Mass Spectrometer (AMS) and a soot-particle AMS for the non-refractory and refractory systems, respectively. We show that the heterogeneous oxidation kinetics of these multicomponent particles are substantially different than that of the single-component particles. The oxidation of organic coatings is rapid, undergoing dramatic changes to carbon oxidation state and losing a significant amount of organic mass after relatively low OH exposures (equivalent to several days of atmospheric processing). In the case of biomass burning particles, the kinetics are complex, with different components (inferred by aerosol mass spectrometry) undergoing oxidation at different rates.

Kinetics, Mechanism, and Secondary Organic Aerosol Yield of Aqueous Phase Photo-oxidation of α-Pinene Oxidation Products.

PubMed

Aljawhary, Dana; Zhao, Ran; Lee, Alex K Y; Wang, Chen; Abbatt, Jonathan P D

2016-03-10

Formation of secondary organic aerosol (SOA) involves atmospheric oxidation of volatile organic compounds (VOCs), the majority of which are emitted from biogenic sources. Oxidation can occur not only in the gas-phase but also in atmospheric aqueous phases such as cloudwater and aerosol liquid water. This study explores for the first time the aqueous-phase OH oxidation chemistry of oxidation products of α-pinene, a major biogenic VOC species emitted to the atmosphere. The kinetics, reaction mechanisms, and formation of SOA compounds in the aqueous phase of two model compounds, cis-pinonic acid (PIN) and tricarballylic acid (TCA), were investigated in the laboratory; TCA was used as a surrogate for 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA), a known α-pinene oxidation product. Aerosol time-of-flight chemical ionization mass spectrometry (Aerosol-ToF-CIMS) was used to follow the kinetics and reaction mechanisms at the molecular level. Room-temperature second-order rate constants of PIN and TCA were determined to be 3.3 (± 0.5) × 10(9) and 3.1 (± 0.2) × 10(8) M(-1) s(-1), respectively, from which were estimated their condensed-phase atmospheric lifetimes. Aerosol-ToF-CIMS detected a large number of products leading to detailed reaction mechanisms for PIN and MBTCA. By monitoring the particle size distribution after drying, the amount of SOA material remaining in the particle phase was determined. An aqueous SOA yield of 40 to 60% was determined for PIN OH oxidation. Although recent laboratory studies have focused primarily on aqueous-phase processing of isoprene-related compounds, we demonstrate that aqueous formation of SOA materials also occurs from monoterpene oxidation products, thus representing an additional source of biogenically driven aerosol formation.

Oxidative damage in DNA bases revealed by UV resonant Raman spectroscopy.

PubMed

D'Amico, Francesco; Cammisuli, Francesca; Addobbati, Riccardo; Rizzardi, Clara; Gessini, Alessandro; Masciovecchio, Claudio; Rossi, Barbara; Pascolo, Lorella

2015-03-07

We report on the use of the UV Raman technique to monitor the oxidative damage of deoxynucleotide triphosphates (dATP, dGTP, dCTP and dTTP) and DNA (plasmid vector) solutions. Nucleotide and DNA aqueous solutions were exposed to hydrogen peroxide (H2O2) and iron containing carbon nanotubes (CNTs) to produce Fenton's reaction and induce oxidative damage. UV Raman spectroscopy is shown to be maximally efficient to reveal changes in the nitrogenous bases during the oxidative mechanisms occurring on these molecules. The analysis of Raman spectra, supported by numerical computations, revealed that the Fenton's reaction causes an oxidation of the nitrogenous bases in dATP, dGTP and dCTP solutions leading to the production of 2-hydroxyadenine, 8-hydroxyguanine and 5-hydroxycytosine. No thymine change was revealed in the dTTP solution under the same conditions. Compared to single nucleotide solutions, plasmid DNA oxidation has resulted in more radical damage that causes the breaking of the adenine and guanine aromatic rings. Our study demonstrates the advantage of using UV Raman spectroscopy for rapidly monitoring the oxidation changes in DNA aqueous solutions that can be assigned to specific nitrogenous bases.

Nanostructured porous Si optical biosensors: effect of thermal oxidation on their performance and properties.

PubMed

Shtenberg, Giorgi; Massad-Ivanir, Naama; Fruk, Ljiljana; Segal, Ester

2014-09-24

The influence of thermal oxidation conditions on the performance of porous Si optical biosensors used for label-free and real-time monitoring of enzymatic activity is studied. We compare three oxidation temperatures (400, 600, and 800 °C) and their effect on the enzyme immobilization efficiency and the intrinsic stability of the resulting oxidized porous Si (PSiO2), Fabry-Pérot thin films. Importantly, we show that the thermal oxidation profoundly affects the biosensing performance in terms of greater optical sensitivity, by monitoring the catalytic activity of horseradish peroxidase and trypsin-immobilized PSiO2. Despite the significant decrease in porous volume and specific surface area (confirmed by nitrogen gas adsorption-desorption studies) with elevating the oxidation temperature, higher content and surface coverage of the immobilized enzymes is attained. This in turn leads to greater optical stability and sensitivity of PSiO2 nanostructures. Specifically, films produced at 800 °C exhibit stable optical readout in aqueous buffers combined with superior biosensing performance. Thus, by proper control of the oxide layer formation, we can eliminate the aging effect, thus achieving efficient immobilization of different biomolecules, optical signal stability, and sensitivity.

Dextran and gelatin based photocrosslinkable tissue adhesive.

PubMed

Wang, Tao; Nie, Jun; Yang, Dongzhi

2012-11-06

A two-component tissue adhesive based on biocompatible and bio-degradable polymers (oxidized urethane dextran (Dex-U-AD) and gelatin) was prepared and photocrosslinked under the ultraviolet (UV) irradiation. The adhesive could adhere to surface of gelatin, which simulated the human tissue steadily. The structures of above Dex-U-AD were characterized by FTIR, (1)H NMR spectroscopy and XRD. The adhesion property of result products was evaluated by lap-shear test. The maximum adhesion strength could reach to 4.16±0.72 MPa which was significantly higher than that of fibrin glue. The photopolymerization process of Dex-U-AD/gelatin was monitored by real time infrared spectroscopy (RTIR). It took less than 5 min to complete the curing process. The cytotoxicity of Dex-U-AD/gelatin also was evaluated which indicated that Dex-U-AD/gelatin gels were nontoxic to L929 cell. The relationship between all the above-mentioned properties and degree of oxidization of Dex-U-AD was assessed. The obtained products have the potential to serve as tissue adhesive in the future. Copyright © 2012 Elsevier Ltd. All rights reserved.

Approaching the limits of cationic and anionic electrochemical activity with the Li-rich layered rocksalt Li3IrO4

NASA Astrophysics Data System (ADS)

Perez, Arnaud J.; Jacquet, Quentin; Batuk, Dmitry; Iadecola, Antonella; Saubanère, Matthieu; Rousse, Gwenaëlle; Larcher, Dominique; Vezin, Hervé; Doublet, Marie-Liesse; Tarascon, Jean-Marie

2017-12-01

The Li-rich rocksalt oxides Li2MO3 (M = 3d/4d/5d transition metal) are promising positive-electrode materials for Li-ion batteries, displaying capacities exceeding 300 mAh g-1 thanks to the participation of the oxygen non-bonding O(2p) orbitals in the redox process. Understanding the oxygen redox limitations and the role of the O/M ratio is therefore crucial for the rational design of materials with improved electrochemical performances. Here we push oxygen redox to its limits with the discovery of a Li3IrO4 compound (O/M = 4) that can reversibly take up and release 3.5 electrons per Ir and possesses the highest capacity ever reported for any positive insertion electrode. By quantitatively monitoring the oxidation process, we demonstrate the material's instability against O2 release on removal of all Li. Our results show that the O/M parameter delineates the boundary between the material's maximum capacity and its stability, hence providing valuable insights for further development of high-capacity materials.

Physico-chemical characterization of engineered metal oxide nanoparticles: the critical role of microscopy

NASA Astrophysics Data System (ADS)

La Fontaine, A.; Coleman, V. A.; Jämting, A. K.; Lawn, M.; Herrmann, J.; Miles, J. R.

2010-06-01

Three different methods for extracting zinc oxide (ZnO) and titanium dioxide (TiO2) nanoparticles from commercially available sunscreen were investigated to determine the most appropriate route for producing a sample suitable for measuring the primary particle size. Direct dilution of the formulation, centrifugal methods and chemical washing were trialed in combination with ultrasonic processing and surfactant addition to generate samples that are suitable for particle size analysis. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) were used to monitor the extraction and re-dispersion process. Washing with hexane, methanol and water to remove the formulation, in combination with pulsed high-powered ultrasonication and the addition of a charge-stabilizing surfactant was found to be the most efficient way of producing de-agglomerated samples. DLS measurements gave average hydrodynamic particle diameters of 87 nm for ZnO and 76 nm for TiO2, compared to equivalent spherical particle diameters of 21 +/- 12 nm for ZnO (81 particles) and 19 +/- 14 nm for TiO2 (81 particles) obtained from TEM analysis.

Field study of nitrous oxide production with in situ aeration in a closed landfill site.

PubMed

Nag, Mitali; Shimaoka, Takayuki; Nakayama, Hirofumi; Komiya, Teppei; Xiaoli, Chai

2016-03-01

Nitrous oxide (N(2)O) has gained considerable attention as a contributor to global warming and depilation of stratospheric ozone layer. Landfill is one of the high emitters of greenhouse gas such as methane and N(2)O during the biodegradation of solid waste. Landfill aeration has been attracted increasing attention worldwide for fast, controlled and sustainable conversion of landfills into a biological stabilized condition, however landfill aeration impel N(2)O emission with ammonia removal. N(2)O originates from the biodegradation, or the combustion of nitrogen-containing solid waste during the microbial process of nitrification and denitrification. During these two processes, formation of N(2)O as a by-product from nitrification, or as an intermediate product of denitrification. In this study, air was injected into a closed landfill site and investigated the major N(2)O production factors and correlations established between them. The in-situ aeration experiment was carried out by three sets of gas collection pipes along with temperature probes were installed at three different distances of one, two and three meter away from the aeration point; named points A-C, respectively. Each set of pipes consisted of three different pipes at three different depths of 0.0, 0.75 and 1.5 m from the bottom of the cover soil. Landfill gases composition was monitored weekly and gas samples were collected for analysis of nitrous oxide concentrations. It was evaluated that temperatures within the range of 30-40°C with high oxygen content led to higher generation of nitrous oxide with high aeration rate. Lower O(2) content can infuse N(2)O production during nitrification and high O(2) inhibit denitrification which would affect N(2)O production. The findings provide insights concerning the production potentials of N(2)O in an aerated landfill that may help to minimize with appropriate control of the operational parameters and biological reactions of N turnover. Investigation of nitrous oxide production potential during in situ aeration in an old landfill site revealed that increased temperatures and oxygen content inside the landfill site are potential factors for nitrous oxide production. Temperatures within the range of optimum nitrification process (30-40°C) induce nitrous oxide formation with high oxygen concentration as a by-product of nitrogen turnover. Decrease of oxygen content during nitrification leads increase of nitrous oxide production, while temperatures above 40°C with moderate and/or low oxygen content inhibit nitrous oxide generation.

Quantitative Monitoring of Microbial Species during Bioleaching of a Copper Concentrate.

PubMed

Hedrich, Sabrina; Guézennec, Anne-Gwenaëlle; Charron, Mickaël; Schippers, Axel; Joulian, Catherine

2016-01-01

Monitoring of the microbial community in bioleaching processes is essential in order to control process parameters and enhance the leaching efficiency. Suitable methods are, however, limited as they are usually not adapted to bioleaching samples and often no taxon-specific assays are available in the literature for these types of consortia. Therefore, our study focused on the development of novel quantitative real-time PCR (qPCR) assays for the quantification of Acidithiobacillus caldus, Leptospirillum ferriphilum, Sulfobacillus thermosulfidooxidans , and Sulfobacillus benefaciens and comparison of the results with data from other common molecular monitoring methods in order to evaluate their accuracy and specificity. Stirred tank bioreactors for the leaching of copper concentrate, housing a consortium of acidophilic, moderately thermophilic bacteria, relevant in several bioleaching operations, served as a model system. The microbial community analysis via qPCR allowed a precise monitoring of the evolution of total biomass as well as abundance of specific species. Data achieved by the standard fingerprinting methods, terminal restriction fragment length polymorphism (T-RFLP) and capillary electrophoresis single strand conformation polymorphism (CE-SSCP) on the same samples followed the same trend as qPCR data. The main added value of qPCR was, however, to provide quantitative data for each species whereas only relative abundance could be deduced from T-RFLP and CE-SSCP profiles. Additional value was obtained by applying two further quantitative methods which do not require nucleic acid extraction, total cell counting after SYBR Green staining and metal sulfide oxidation activity measurements via microcalorimetry. Overall, these complementary methods allow for an efficient quantitative microbial community monitoring in various bioleaching operations.

Quantitative Monitoring of Microbial Species during Bioleaching of a Copper Concentrate

PubMed Central

Hedrich, Sabrina; Guézennec, Anne-Gwenaëlle; Charron, Mickaël; Schippers, Axel; Joulian, Catherine

2016-01-01

Monitoring of the microbial community in bioleaching processes is essential in order to control process parameters and enhance the leaching efficiency. Suitable methods are, however, limited as they are usually not adapted to bioleaching samples and often no taxon-specific assays are available in the literature for these types of consortia. Therefore, our study focused on the development of novel quantitative real-time PCR (qPCR) assays for the quantification of Acidithiobacillus caldus, Leptospirillum ferriphilum, Sulfobacillus thermosulfidooxidans, and Sulfobacillus benefaciens and comparison of the results with data from other common molecular monitoring methods in order to evaluate their accuracy and specificity. Stirred tank bioreactors for the leaching of copper concentrate, housing a consortium of acidophilic, moderately thermophilic bacteria, relevant in several bioleaching operations, served as a model system. The microbial community analysis via qPCR allowed a precise monitoring of the evolution of total biomass as well as abundance of specific species. Data achieved by the standard fingerprinting methods, terminal restriction fragment length polymorphism (T-RFLP) and capillary electrophoresis single strand conformation polymorphism (CE-SSCP) on the same samples followed the same trend as qPCR data. The main added value of qPCR was, however, to provide quantitative data for each species whereas only relative abundance could be deduced from T-RFLP and CE-SSCP profiles. Additional value was obtained by applying two further quantitative methods which do not require nucleic acid extraction, total cell counting after SYBR Green staining and metal sulfide oxidation activity measurements via microcalorimetry. Overall, these complementary methods allow for an efficient quantitative microbial community monitoring in various bioleaching operations. PMID:28066365

Silver Nanoparticle Modified Electrode Covered by Graphene Oxide for the Enhanced Electrochemical Detection of Dopamine

PubMed Central

Shin, Jae-Wook; Kim, Kyeong-Jun; Yoon, Jinho; Jo, Jinhee; El-Said, Waleed Ahmed; Choi, Jeong-Woo

2017-01-01

Several neurological disorders such as Alzheimer’s disease and Parkinson’s disease have become a serious impediment to aging people nowadays. One of the efficient methods used to monitor these neurological disorders is the detection of neurotransmitters such as dopamine. Metal materials, such as gold and platinum, are widely used in this electrochemical detection method; however, low sensitivity and linearity at low dopamine concentrations limit the use of these materials. To overcome these limitations, a silver nanoparticle (SNP) modified electrode covered by graphene oxide for the detection of dopamine was newly developed in this study. For the first time, the surface of an indium tin oxide (ITO) electrode was modified using SNPs and graphene oxide sequentially through the electrochemical deposition method. The developed biosensor provided electrochemical signal enhancement at low dopamine concentrations in comparison with previous biosensors. Therefore, our newly developed SNP modified electrode covered by graphene oxide can be used to monitor neurological diseases through electrochemical signal enhancement at low dopamine concentrations. PMID:29186040

Silver Nanoparticle Modified Electrode Covered by Graphene Oxide for the Enhanced Electrochemical Detection of Dopamine.

PubMed

Shin, Jae-Wook; Kim, Kyeong-Jun; Yoon, Jinho; Jo, Jinhee; El-Said, Waleed Ahmed; Choi, Jeong-Woo

2017-11-29

Several neurological disorders such as Alzheimer's disease and Parkinson's disease have become a serious impediment to aging people nowadays. One of the efficient methods used to monitor these neurological disorders is the detection of neurotransmitters such as dopamine. Metal materials, such as gold and platinum, are widely used in this electrochemical detection method; however, low sensitivity and linearity at low dopamine concentrations limit the use of these materials. To overcome these limitations, a silver nanoparticle (SNP) modified electrode covered by graphene oxide for the detection of dopamine was newly developed in this study. For the first time, the surface of an indium tin oxide (ITO) electrode was modified using SNPs and graphene oxide sequentially through the electrochemical deposition method. The developed biosensor provided electrochemical signal enhancement at low dopamine concentrations in comparison with previous biosensors. Therefore, our newly developed SNP modified electrode covered by graphene oxide can be used to monitor neurological diseases through electrochemical signal enhancement at low dopamine concentrations.

Electrical Resistance as a NDE Technique to Monitor Processing and Damage Accumulation in SiC/SiC Composites

NASA Technical Reports Server (NTRS)

Smith, Craig; Morscher, Gregory N.; Xia, Zhenhai

2008-01-01

Ceramic matrix composites are suitable for high temperature structural applications such as turbine airfoils and hypersonic thermal protection systems. The employment of these materials in such applications is limited by the ability to process components reliable and to accurately monitor and predict damage evolution that leads to failure under stressed-oxidation conditions. Current nondestructive methods such as ultrasound, x-ray, and thermal imaging are limited in their ability to quantify small scale, transverse, in-plane, matrix cracks developed over long-time creep and fatigue conditions. Electrical resistance of SiC/SiC composites is one technique that shows special promise towards this end. Since both the matrix and the fibers are conductive, changes in matrix or fiber properties should relate to changes in electrical conductivity along the length of a specimen or part. Initial efforts to quantify the electrical resistance of different fiber and different matrix SiC/SiC composites will be presented. Also, the effect of matrix cracking on electrical resistivity for several composite systems will be presented. The implications towards electrical resistance as a technique applied to composite processing, damage detection, and life-modeling will be discussed.

Applications of optical measurement technology in pollution gas monitoring at thermal power plants

NASA Astrophysics Data System (ADS)

Wang, Jian; Yu, Dahai; Ye, Huajun; Yang, Jianhu; Ke, Liang; Han, Shuanglai; Gu, Haitao; Chen, Yingbin

2011-11-01

This paper presents the work of using advanced optical measurement techniques to implement stack gas emission monitoring and process control. A system is designed to conduct online measurement of SO2/NOX and mercury emission from stacks and slipping NH3 of de-nitrification process. The system is consisted of SO2/NOX monitoring subsystem, mercury monitoring subsystem, and NH3 monitoring subsystem. The SO2/NOX monitoring subsystem is developed based on the ultraviolet differential optical absorption spectroscopy (UV-DOAS) technique. By using this technique, a linearity error less than +/-1% F.S. is achieved, and the measurement errors resulting from optical path contamination and light fluctuation are removed. Moreover, this subsystem employs in situ extraction and hot-wet line sampling technique to significantly reduce SO2 loss due to condensation and protect gas pipeline from corrosion. The mercury monitoring subsystem is used to measure the concentration of element mercury (Hg0), oxidized mercury (Hg2+), and total gaseous mercury (HgT) in the flue gas exhaust. The measurement of Hg with a low detection limit (0.1μg/m3) and a high sensitivity is realized by using cold vapor atom fluorescence spectroscopy (CVAFS) technique. This subsystem is also equipped with an inertial separation type sampling technique to prevent gas pipeline from being clogged and to reduce speciation mercury measurement error. The NH3 monitoring subsystem is developed to measure the concentration of slipping NH3 and then to help improving the efficiency of de-nitrification. The NH3 concentration as low as 0.1ppm is able to be measured by using the off-axis integrated cavity output spectroscopy (ICOS) and the tunable diode laser absorption spectroscopy (TDLAS) techniques. The problem of trace NH3 sampling loss is solved by applying heating the gas pipelines when the measurement is running.

Eddy current sensor for in-situ monitoring of swelling of Li-ion prismatic cells

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

Plotnikov, Yuri, E-mail: plotnikov@ge.com; Karp, Jason, E-mail: plotnikov@ge.com; Knobloch, Aaron, E-mail: plotnikov@ge.com

2015-03-31

In-situ monitoring an on-board rechargeable battery in hybrid cars can be used to ensure a long operating life of the battery and safe operation of the vehicle. Intercalations of ions in the electrode material during charge and discharge of a Lithium Ion battery cause periodic stress and strain of the electrode materials that can ultimately lead to fatigue resulting in capacity loss and potential battery failure. Currently this process is not monitored directly on the cells. This work is focused on development technologies that would quantify battery swelling and provide in-situ monitoring for onboard vehicle applications. Several rounds of testsmore » have been performed to spatially characterize cell expansion of a 5 Ah cell with a nickel/manganese/cobalt-oxide cathode (Sanyo, Japan) used by Ford in their Fusion HEV battery pack. A collaborative team of researchers from GE and the University of Michigan has characterized the free expansion of these cells to be in the range of 100×125 microns (1% of total cell thickness) at the center point of the cell. GE proposed to use a thin eddy current (EC) coil to monitor these expansions on the cells while inside the package. The photolithography manufacturing process previously developed for EC arrays for detecting cracks in aircraft engine components was used to build test coils for gap monitoring. These sensors are thin enough to be placed safely between neighboring cells and capable of monitoring small variations in the gap between the cells. Preliminary investigations showed that these coils can be less than 100 micron thick and have sufficient sensitivity in a range from 0 to 2 mm. Laboratory tests revealed good correlation between EC and optical gap measurements in the desired range. Further technology development could lead to establishing a sensor network for a low cost solution for the in-situ monitoring of cell swelling during battery operation.« less

Eddy current sensor for in-situ monitoring of swelling of Li-ion prismatic cells

NASA Astrophysics Data System (ADS)

Plotnikov, Yuri; Karp, Jason; Knobloch, Aaron; Kapusta, Chris; Lin, David

2015-03-01

In-situ monitoring an on-board rechargeable battery in hybrid cars can be used to ensure a long operating life of the battery and safe operation of the vehicle. Intercalations of ions in the electrode material during charge and discharge of a Lithium Ion battery cause periodic stress and strain of the electrode materials that can ultimately lead to fatigue resulting in capacity loss and potential battery failure. Currently this process is not monitored directly on the cells. This work is focused on development technologies that would quantify battery swelling and provide in-situ monitoring for onboard vehicle applications. Several rounds of tests have been performed to spatially characterize cell expansion of a 5 Ah cell with a nickel/manganese/cobalt-oxide cathode (Sanyo, Japan) used by Ford in their Fusion HEV battery pack. A collaborative team of researchers from GE and the University of Michigan has characterized the free expansion of these cells to be in the range of 100×125 microns (1% of total cell thickness) at the center point of the cell. GE proposed to use a thin eddy current (EC) coil to monitor these expansions on the cells while inside the package. The photolithography manufacturing process previously developed for EC arrays for detecting cracks in aircraft engine components was used to build test coils for gap monitoring. These sensors are thin enough to be placed safely between neighboring cells and capable of monitoring small variations in the gap between the cells. Preliminary investigations showed that these coils can be less than 100 micron thick and have sufficient sensitivity in a range from 0 to 2 mm. Laboratory tests revealed good correlation between EC and optical gap measurements in the desired range. Further technology development could lead to establishing a sensor network for a low cost solution for the in-situ monitoring of cell swelling during battery operation.

Instrumentation for air quality measurements.

NASA Technical Reports Server (NTRS)

Loewenstein, M.

1973-01-01

Comparison of the new generation of air quality monitoring instruments with some more traditional methods. The first generation of air quality measurement instruments, based on the use of oxidant coulometric cells, nitrogen oxide colorimetry, carbon monoxide infrared analyzers, and other types of detectors, is compared with new techniques now coming into wide use in the air monitoring field and involving the use of chemiluminescent reactions, optical absorption detectors, a refinement of the carbon monoxide infrared analyzer, electrochemical cells based on solid electrolytes, and laser detectors.

Electronically conducting metal oxide nanoparticles and films for optical sensing applications

DOEpatents

Ohodnicki, Jr., Paul R.; Wang, Congjun; Andio, Mark A

2014-09-16

The disclosure relates to a method of detecting a change in a chemical composition by contacting a conducting oxide material with a monitored stream, illuminating the conducting oxide material with incident light, collecting exiting light, monitoring an optical signal based on a comparison of the incident light and the exiting light, and detecting a shift in the optical signal. The conducting metal oxide has a carrier concentration of at least 10.sup.17/cm.sup.3, a bandgap of at least 2 eV, and an electronic conductivity of at least 10.sup.-1 S/cm, where parameters are specified at the gas stream temperature. The optical response of the conducting oxide materials is proposed to result from the high carrier concentration and electronic conductivity of the conducting metal oxide, and the resulting impact of changing gas atmospheres on that relatively high carrier concentration and electronic conductivity. These changes in effective carrier densities and electronic conductivity of conducting metal oxide films and nanoparticles are postulated to be responsible for the change in measured optical absorption associated with free carriers. Exemplary conducting metal oxides include but are not limited to Al-doped ZnO, Sn-doped In.sub.2O.sub.3, Nb-doped TiO.sub.2, and F-doped SnO.sub.2.

A method and apparatus for monitoring the level of tritiated water vapor in air using a solid scintillator.

PubMed

Campi, F; Edwards, R A; Ossiri, A; Pacenti, P; Terrani, S

1998-08-01

Tritium is presently used in large quantities in laboratories for technological studies, as fuel for the process of nuclear fusion, and in the manufacture of radio-luminescent items. It is also produced in fission nuclear plants (with a yield of 10(-4) if the fuel is 235U and twice as much if the fuel is 239Pu), particularly in those which use D2O as moderator. The weak energy of beta particles (Emean=5.7 keV) produced by tritium implies that it is only harmful if internalized. In nature tritium in air is mainly present under two different chemical forms: elementary (HT, DT, T2) and oxidized (HTO, DTO, T2O). The latter is extremely more dangerous than the former as far as radioprotection is concerned; for this reason the derived air concentration limit (8 x 10(5) Bq m(-3)) for the gaseous form is 25,000 times higher than the value for the oxidized one. The purpose of the work presented here is to realize an area monitor that is able to discriminate in real time between the two chemical forms. Using the properties of zeolite as an absorber and scintillator, it was possible to construct such a detector. In 1 h the instrument can reveal HTO concentrations 40 times below the derived air concentration. A concentration equal to the derived air concentration can be revealed within the first minute of counting and the performance may be further improved. Moreover, the prototype realized is able to work automatically and continuously for 5 h. The capability of discriminating the oxidized chemical form, the sensitivity, and the possibility of obtaining real time information make this instrument a good monitor in those cases where there is a real risk of tritium air contamination.

Control of size and viscoelastic properties of nanofibrillated cellulose from palm tree by varying the TEMPO-mediated oxidation time.

PubMed

Benhamou, Karima; Dufresne, Alain; Magnin, Albert; Mortha, Gérard; Kaddami, Hamid

2014-01-01

The main objective of the present study was to control and optimize the preparation of nanofibrillated cellulose (NFC) from the date palm tree by monitoring the oxidation time (degree of oxidation) of the pristine cellulose and the number of cycles through the homogenizer. The oxidation was monitored by TEMPO (1-oxo-2,2,6,6-tétraméthylpipyridine 1-oxyle) mediated oxidation. Evidence of the successful isolation of NFC was given by FE-SEM observation revealing fibrils with a width in the range 20-30nm, depending of the oxidation time. The evolution of the transparency of the aqueous NFC suspension and carboxylic content according to the degree of oxidation and number of cycles were also analyzed by UV-vis transmittance, Fourier-transform infrared spectroscopy (FT-IR), conductimetry, and X-ray diffraction analysis. A significant NFC length reduction occurred during the TEMPO-mediated oxidation. The rheological properties of NFC suspensions were characterized as function of the oxidation time. Dynamic rheology showed that the aqueous suspension behavior changed from liquid to gel depending on the concentration. The highest concentration studied was 1wt% and the modulus reached 1MPa which was higher than for non-oxidized NFC. An explanation of the gel structure evolution with the oxidation time applied to the NFC (NFC length) was proposed. The gel structure evolves from an entanglement-governed gel structure to an immobilized water molecule-governed one. Copyright © 2013 Elsevier Ltd. All rights reserved.

40 CFR 63.4568 - What are the requirements for continuous parameter monitoring system installation, operation, and...

Code of Federal Regulations, 2010 CFR

2010-07-01

..., install a gas temperature monitor in the firebox of the thermal oxidizer or in the duct immediately... gas temperature monitors upstream and/or downstream of the catalyst bed as required in § 63.3967(b... (a) and (c)(3)(i) through (v) of this section for each gas temperature monitoring device. (i) Locate...

40 CFR 63.4568 - What are the requirements for continuous parameter monitoring system installation, operation, and...

Code of Federal Regulations, 2011 CFR

2011-07-01

..., install a gas temperature monitor in the firebox of the thermal oxidizer or in the duct immediately... gas temperature monitors upstream and/or downstream of the catalyst bed as required in § 63.3967(b... (a) and (c)(3)(i) through (v) of this section for each gas temperature monitoring device. (i) Locate...

The Oxidation of CVD Silicon Carbide in Carbon Dioxide

NASA Technical Reports Server (NTRS)

Opila, Elizabeth J.; Nguyen, QuynchGiao N.

1997-01-01

Chemically-vapor-deposited silicon carbide (CVD SiC) was oxidized in carbon dioxide (CO2) at temperatures of 1200-1400 C for times between 100 and 500 hours at several gas flow rates. Oxidation weight gains were monitored by thermogravimetric analysis (TGA) and were found to be very small and independent of temperature. Possible rate limiting kinetic laws are discussed. Oxidation of SiC by CO2 is negligible compared to the rates measured for other oxidants typically found in combustion environments: oxygen and water vapor.

Applications of chemiluminescence to bacterial analysis

NASA Technical Reports Server (NTRS)

Searle, N. D.

1975-01-01

Luminol chemiluminescence method for detecting bacteria was based on microbial activation of the oxidation of the luminol monoanion by hydrogen peroxide. Elimination of the prior lysing step, previously used in the chemiluminescence technique, was shown to improve considerably the reproducibility and accuracy of the method in addition to simplifying it. An inexpensive, portable photomultiplier detector was used to measure the maximum light intensity produced when the sample is added to the reagent. Studies of cooling tower water show that the luminol chemiluminescence technique can be used to monitor changes in viable cell population both under normal conditions and during chlorine treatment. Good correlation between chemiluminescence and plate counts was also obtained in the analysis of process water used in paper mills. This method showed good potential for monitoring the viable bacteria populations in activated sludge used in waste treatment plants to digest organic matter.

Real-time monitoring of methane oxidation in a simulated landfill cover soil and MiSeq pyrosequencing analysis of the related bacterial community structure.

PubMed

Xing, Zhilin; Zhao, Tiantao; Gao, Yanhui; He, Zhi; Zhang, Lijie; Peng, Xuya; Song, Liyan

2017-10-01

Real-time CH 4 oxidation in a landfill cover soil was studied using automated gas sampling that determined biogas (CH 4 and CO 2 ) and O 2 concentrations at various depths in a simulated landfill cover soil (SLCS) column reactor. The real-time monitoring system obtained more than 10,000 biogas (CH 4 and CO 2 ) and O 2 data points covering 32 steady states of CH 4 oxidation with 32 different CH 4 fluxes (0.2-125mol·m -2 ·d -1 ). The kinetics of CH 4 oxidation at different depths (0-20cm, 20-40cm, and 40-60cm) of SLCS were well fit by a CH 4 -O 2 dual-substrate model based on 32 values (averaged, n=5-15) of equilibrated CH 4 concentrations. The quality of the fit (R 2 ranged from 0.90 to 0.96) was higher than those reported in previous studies, which suggests that real time monitoring is beneficial for CH 4 oxidation simulations. MiSeq pyrosequencing indicated that CH 4 flux events changed the bacterial community structure (e.g., increased the abundance of Bacteroidetes and Methanotrophs) and resulted in a relative increase in the amount of type I methanotrophs (Methylobacter and Methylococcales) and a decrease in the amount of type II methanotrophs (Methylocystis). Copyright © 2017 Elsevier Ltd. All rights reserved.

Clean Air Markets - Part 75 Emissions Monitoring Policy Manual

EPA Pesticide Factsheets

Learn about monitoring mass sulfur dioxide and mass carbon dioxide emissions, nitrogen oxide emission rate, and heat input by units affected by the Acid Rain Program and the Clean Air Interstate Rule.

Atomic-scale electrochemistry on the surface of a manganite

DOE PAGES

Vasudevan, Rama K.; Tselev, Alexander; Baddorf, Arthur P.; ...

2015-04-09

The doped manganese oxides (manganites) have been widely studied for their colossal magnetoresistive effects, for potential applications in oxide spintronics, electroforming in resistive switching devices, and are materials of choice as cathodes in modern solid oxide fuel cells. However, little experimental knowledge of the dynamics of the surfaces of perovskite manganites at the atomic scale exists. Here, through in-situ scanning tunnelling microscopy (STM), we demonstrate atomic resolution on samples of La 0.625Ca 0.375MnO 3 grown on (001) SrTiO 3 by pulsed laser deposition (PLD). Furthermore, by applying triangular DC waveforms of increasing amplitude to the STM tip, and measuring themore » tunnelling current, we demonstrate the ability to both perform and monitor surface electrochemical processes at the atomic level, including, for the first time in a manganite, formation of single and multiple oxygen vacancies, disruption of the overlying manganite layers, and removal and deposition of individual atomic units or clusters. Our work paves the way for better understanding of surface oxygen reactions in these systems.« less

Global Profiling of Reactive Oxygen and Nitrogen Species in Biological Systems

PubMed Central

Zielonka, Jacek; Zielonka, Monika; Sikora, Adam; Adamus, Jan; Joseph, Joy; Hardy, Micael; Ouari, Olivier; Dranka, Brian P.; Kalyanaraman, Balaraman

2012-01-01

Herein we describe a high-throughput fluorescence and HPLC-based methodology for global profiling of reactive oxygen and nitrogen species (ROS/RNS) in biological systems. The combined use of HPLC and fluorescence detection is key to successful implementation and validation of this methodology. Included here are methods to specifically detect and quantitate the products formed from interaction between the ROS/RNS species and the fluorogenic probes, as follows: superoxide using hydroethidine, peroxynitrite using boronate-based probes, nitric oxide-derived nitrosating species with 4,5-diaminofluorescein, and hydrogen peroxide and other oxidants using 10-acetyl-3,7-dihydroxyphenoxazine (Amplex® Red) with and without horseradish peroxidase, respectively. In this study, we demonstrate real-time monitoring of ROS/RNS in activated macrophages using high-throughput fluorescence and HPLC methods. This global profiling approach, simultaneous detection of multiple ROS/RNS products of fluorescent probes, developed in this study will be useful in unraveling the complex role of ROS/RNS in redox regulation, cell signaling, and cellular oxidative processes and in high-throughput screening of anti-inflammatory antioxidants. PMID:22139901

Arbuscular mycorrhizal fungal inoculation increases phenolic synthesis in clover roots via hydrogen peroxide, salicylic acid and nitric oxide signaling pathways.

PubMed

Zhang, Rui-Qin; Zhu, Hong-Hui; Zhao, Hai-Quan; Yao, Qing

2013-01-01

Arbuscular mycorrhizal fungi can increase the host resistance to pathogens via promoted phenolic synthesis, however, the signaling pathway responsible for it still remains unclear. In this study, in order to reveal the signaling molecules involved in this process, we inoculated Trifolium repense L. with an arbuscular mycorrhizal fungus (AMF), Glomus mosseae, and monitored the contents of phenolics and signaling molecules (hydrogen peroxide (H(2)O(2)), salicylic acid (SA), and nitric oxide (NO)) in roots, measured the activities of l-phenylalanine ammonia-lyase (PAL) and nitric oxide synthase (NOS), and the expression of pal and chs genes. Results demonstrated that AMF colonization promoted the phenolic synthesis, in parallel with the increase in related enzyme activity and gene expression. Meanwhile, the accumulation of all three signaling molecules was also up-regulated by AMF. This study suggested that AMF increased the phenolic synthesis in roots probably via signaling pathways of H(2)O(2), SA and NO in a signaling cascade. Copyright © 2012 Elsevier GmbH. All rights reserved.

Self-adaption of methane-producing communities to pH disturbance at different acetate concentrations by shifting pathways and population interaction.

PubMed

Hao, Liping; Lü, Fan; Li, Lei; Wu, Qing; Shao, Liming; He, Pinjing

2013-07-01

To investigate the competition among acetate-utilizing microorganisms at different acetate levels, bioconversion processes of 50, 100, 150 and 200 mM acetate in the presence and absence of methanogenic inhibitor CH3F were monitored in thermophilic methanogenic system. The successive response of methane-producing community during the deteriorative and recovery phases caused by pH disturbance was analyzed. High acetate concentration (>50mM) inhibited the activity of acetoclastic methanogenesis (AM). The increasing pH (>7.5) enhanced this inhibition. The syntrophic acetate oxidizing (SAO) bacteria and hydrogenotrophic methanogens including Methanomicrobiales and Methanobacteirales were more tolerant to the stress from high acetate concentration and high pH. Resumption from alkali condition to normal pH stimulated the growth of acetate oxidizing syntrophs. The reaction rate of SAO-HM was lower than that of AM. These results point to the possibility to regenerate the deteriorated anaerobic digesters by addition of acclimatized inocula rich in acetate-oxidizing syntrophs. Copyright © 2013 Elsevier Ltd. All rights reserved.

Aqueous Mesocosm Techniques Enabling the Real-Time Measurement of the Chemical and Isotopic Kinetics of Dissolved Methane and Carbon Dioxide.

PubMed

Chan, Eric W; Kessler, John D; Shiller, Alan M; Joung, DongJoo; Colombo, Frank

2016-03-15

Previous studies of microbially mediated methane oxidation in oceanic environments have examined the many different factors that control the rates of oxidation. However, there is debate on what factor(s) are limiting in these types of environments. These factors include the availability of methane, O2, trace metals, nutrients, the density of cell population, and the influence that CO2 production may have on pH. To look at this process in its entirety, we developed an automated mesocosm incubation system with a Dissolved Gas Analysis System (DGAS) coupled to a myriad of analytical tools to monitor chemical changes during methane oxidation. Here, we present new high temporal resolution techniques for investigating dissolved methane and carbon dioxide concentrations and stable isotopic dynamics during aqueous mesocosm and pure culture incubations. These techniques enable us to analyze the gases dissolved in solution and are nondestructive to both the liquid media and the analyzed gases enabling the investigation of a mesocosm or pure culture experiment in a completely closed system, if so desired.

Vapor deposition of molybdenum oxide using bis(ethylbenzene) molybdenum and water

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

Drake, Tasha L.; Stair, Peter C., E-mail: pstair@u.northwestern.edu

2016-09-15

Three molybdenum precursors—bis(acetylacetonate) dioxomolybdenum, molybdenum isopropoxide, and bis(ethylbenzene) molybdenum—were tested for molybdenum oxide vapor deposition. Quartz crystal microbalance studies were performed to monitor growth. Molybdenum isopropoxide and bis(ethylbenzene) molybdenum achieved linear growth rates 0.01 and 0.08 Å/cycle, respectively, using atomic layer deposition techniques. Negligible MoO{sub x} growth was observed on alumina powder using molybdenum isopropoxide, as determined by inductively coupled plasma optical emission spectroscopy. Bis(ethylbenzene) molybdenum achieved loadings of 0.5, 1.1, and 1.9 Mo/nm{sup 2} on alumina powder after one, two, and five cycles, respectively, using atomic layer deposition techniques. The growth window for bis(ethylbenzene) molybdenum is 135–150 °C. An alternative pulsingmore » strategy was also developed for bis(ethylbenzene) molybdenum that results in higher growth rates in less time compared to atomic layer deposition techniques. The outlined process serves as a methodology for depositing molybdenum oxide for catalytic applications. All as-deposited materials undergo further calcination prior to characterization and testing.« less

A Fast Responsive Ultraviolet Sensor from mSILAR-Processed Sn-ZnO

NASA Astrophysics Data System (ADS)

Thomas, Deepu; Vijayalakshmi, K. A.; Sadasivuni, Kishor Kumar; Thomas, Ajith; Ponnamma, Deepalekshmi; Cabibihan, John-John

2017-11-01

Microwave-assisted successive ionic layer adsorption and reaction was employed to synthesize Sn-ZnO (tin-doped zinc oxide), and its sensitivity to ultraviolet radiation is compared with zinc oxide (ZnO). The sensing films were made by the dip-coated method on an indium titanium oxide glass substrate, and the sensing performance was monitored using the 300-700 nm wavelength of UV-Vis light. Excellent sensitivity and recovery were observed for the Sn-doped ZnO sensor device, especially at 380 nm wavelength of ultraviolet (UV) light (response and recovery time 2.26 s and 8.63 s, respectively, at 5 V bias voltage). The variation in photocurrent with respect to dark and light illumination atmosphere was well illustrated based on the Schottky and inter-particle network effects. Doping of Sn on ZnO nanoparticles varied the surface roughness and crystallite size as observed from scanning electron microscopic and x-ray diffraction studies. Here, we demonstrate a simple and economical fabrication technique for designing a high-performance UV light sensor. The developed device works at room temperature with high durability and stability.

Flotation and flocculation chemistry of coal and oxidized coals

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

Somasundaran, P.

1990-01-01

The objective of this research project is to understand the fundamentals involved in the flotation and flocculation of coal and oxidized coals and elucidate mechanisms by which surface interactions between coal and various reagents enhance coal beneficiation. An understanding of the nature of the heterogeneity of coal surfaces arising from the intrinsic distribution of chemical moieties is fundamental to the elucidation of mechanism of coal surface modification and its role in interfacial processes such as flotation, flocculation and agglomeration. A new approach for determining the distribution in surface properties of coal particles was developed in this study and various techniquesmore » capable of providing such information were identified. Distributions in surface energy, contact angle and wettability were obtained using novel techniques such as centrifugal immersion and film flotation. Changes in these distributions upon oxidation and surface modifications were monitored and discussed. An approach to the modelling of coal surface site distributions based on thermodynamic information obtained from gas adsorption and immersion calorimetry is proposed. Polyacrylamide and dodecane was used to alter the coal surface. Methanol adsorption was also studied. 62 figs.« less

The effect of upper gastrointestinal system endoscopy process on serum oxidative stress levels.

PubMed

Turan, Mehmet Nuri; Aslan, Mehmet; Bolukbas, Filiz Fusun; Bolukbas, Cengiz; Selek, Sahbettin; Sabuncu, Tevfik

2016-12-01

Some authors have investigated the effects of oxidative stress in some process such as undergoing laparoscopic. However, the effect of upper gastrointestinal system endoscopy process on oxidative stress is unclear. We evaluated the short-term effect of upper gastrointestinal system endoscopy process on oxidative stress. Thirty patients who underwent endoscopy process and 20 healthy controls were enrolled in the prospective study. Serum total antioxidant capacity and total oxidant status measurements were measured before and after endoscopy process. The ratio percentage of total oxidant status to total antioxidant capacity was regarded as oxidative stress index. Before endoscopy process, serum total antioxidant capacity levels were higher, while serum total oxidant status levels and oxidative stress index values were lower in patients than controls, but this difference was not statistically significant (all, p > 0.05). After endoscopy process, serum total antioxidant capacity and total oxidant status levels were significantly higher in patients than before endoscopy process (both, p < 0.05). However, oxidative stress index values were slight higher in patients but this difference was not statistically significant (p > 0.05). We observed that serum TAC and TOS levels were increased in patients who underwent endoscopy process after endoscopy process. However, short-time upper gastrointestinal system endoscopy process did not cause an important change in the oxidative stress index. Further studies enrolling a larger number of patients are required to clarify the results obtained here.

Real-time Monitoring of Intermediates Reveals the Reaction Pathway in the Thiol-Disulfide Exchange between Disulfide Bond Formation Protein A (DsbA) and B (DsbB) on a Membrane-immobilized Quartz Crystal Microbalance (QCM) System*

PubMed Central

Yazawa, Kenjiro; Furusawa, Hiroyuki; Okahata, Yoshio

2013-01-01

Disulfide bond formation protein B (DsbBS-S,S-S) is an inner membrane protein in Escherichia coli that has two disulfide bonds (S-S, S-S) that play a role in oxidization of a pair of cysteine residues (SH, SH) in disulfide bond formation protein A (DsbASH,SH). The oxidized DsbAS-S, with one disulfide bond (S-S), can oxidize proteins with SH groups for maturation of a folding preprotein. Here, we have described the transient kinetics of the oxidation reaction between DsbASH,SH and DsbBS-S,S-S. We immobilized DsbBS-S,S-S embedded in lipid bilayers on the surface of a 27-MHz quartz crystal microbalance (QCM) device to detect both formation and degradation of the reaction intermediate (DsbA-DsbB), formed via intermolecular disulfide bonds, as a mass change in real time. The obtained kinetic parameters (intermediate formation, reverse, and oxidation rate constants (kf, kr, and kcat, respectively) indicated that the two pairs of cysteine residues in DsbBS-S,S-S were more important for the stability of the DsbA-DsbB intermediate than ubiquinone, an electron acceptor for DsbBS-S,S-S. Our data suggested that the reaction pathway of almost all DsbASH,SH oxidation processes would proceed through this stable intermediate, avoiding the requirement for ubiquinone. PMID:24145032

Characterization of procyanidin B2 oxidation products in an apple juice model solution and confirmation of their presence in apple juice by high-performance liquid chromatography coupled to electrospray ion trap mass spectrometry.

PubMed

Poupard, Pascal; Sanoner, Philippe; Baron, Alain; Renard, Catherine M G C; Guyot, Sylvain

2011-11-01

Procyanidins (i.e. condensed tannins) are polyphenols commonly found in fruits. During juice and cider making, apple polyphenol oxidase catalyzes the oxidation of caffeoylquinic acid (CQA) into its corresponding o-quinone which further reacts with procyanidins and other polyphenols, leading to the formation of numerous oxidation products. However, the structure and the reaction pathways of these neoformed phenolic compounds are still largely unknown. Experiments were carried out on a model system to gain insights into the chemical processes occurring during the initial steps of fruit processing. Procyanidin B2 was oxidized by caffeoylquinic acid o-quinone (CQAoq) in an apple juice model solution. The reaction products were monitored using high performance liquid chromatography (HPLC) coupled to ultraviolet (UV)-visible and electrospray tandem mass spectrometry (ESI-MS/MS) in the negative mode. Oxidative conversion of procyanidin B2 ([M-H](-) at m/z 577) into procyanidin A2 at m/z 575 was unambiguously confirmed. In addition, several classes of products were characterized by their deprotonated molecules ([M-H](-)) and their MS/MS fragmentation patterns: hetero-dimers (m/z 929) and homo-dimers (m/z 1153 and 705) resulting from dimerization involving procyanidin and CQA molecules; intramolecular addition products at m/z 575, 573, 927, 1151 and 703. Interestingly, no extensive polymerization was observed. Analysis of a cider apple juice enabled comparison with the results obtained on a biosynthetic model solution. However, procyanidin A2 did not accumulate but seemed to be an intermediate in the formation of an end-product at m/z 573 for which two structural hypotheses are given. These structural modifications of native polyphenols as a consequence of oxidation probably have an impact on the organoleptic and nutritional properties of apple juices and other apple-derived foods. Copyright © 2011 John Wiley & Sons, Ltd.

40 CFR Table 7 to Subpart Hhhhhhh... - Calibration and Accuracy Requirements for Continuous Parameter Monitoring Systems

Code of Federal Regulations, 2014 CFR

2014-07-01

... CPMS for physical and operational integrity and all electrical connections for oxidation and galvanic... for integrity, oxidation and galvanic corrosion if CPMS is not equipped with a redundant pressure...

40 CFR Table 7 to Subpart Hhhhhhh... - Calibration and Accuracy Requirements for Continuous Parameter Monitoring Systems

Code of Federal Regulations, 2013 CFR

2013-07-01

... CPMS for physical and operational integrity and all electrical connections for oxidation and galvanic... for integrity, oxidation and galvanic corrosion if CPMS is not equipped with a redundant pressure...

Pilot-scale UV/H2O2 study for emerging organic contaminants decomposition.

PubMed

Chu, Xiaona; Xiao, Yan; Hu, Jiangyong; Quek, Elaine; Xie, Rongjin; Pang, Thomas; Xing, Yongjie

2016-03-01

Human behaviors including consumption of drugs and use of personal care products, climate change, increased international travel, and the advent of water reclamation for direct potable use have led to the introduction of significant amounts of emerging organic contaminants into the aqueous environment. In addition, the lower detection limits associated with improved scientific methods of chemical analysis have resulted in a recent increase in documented incidences of these contaminants which previously were not routinely monitored in water. Such contaminants may cause known or suspected adverse ecological and/or human health effects at very low concentrations. Conventional drinking water treatment processes may not effectively remove these organic contaminants. Advanced oxidation process (AOP) is a promising treatment process for the removal of most of these emerging organic contaminants, and has been accepted worldwide as a suitable treatment process. In this study, different groups of emerging contaminants were studied for decomposition efficiency using pilot-scale UV/H2O2 oxidation setup, including EDCs, PPCPs, taste and odor (T&O), and perfluorinated compounds. Results found that MP UV/H2O2 AOP was efficient in removing all the selected contaminants except perfluorinated compounds. Study of the kinetics of the process showed that both light absorption and quantum yield of each compound affected the decomposition performance. Analysis of water quality parameters of the treated water indicated that the outcome of both UV photolysis and UV/H2O2 processes can be affected by changes in the feed water quality.

Monitoring nitric oxide (NO) in rat locus coeruleus: differential effects of NO synthase inhibitors.

PubMed

Desvignes, C; Robert, F; Vachette, C; Chouvet, G; Cespuglio, R; Renaud, B; Lambás-Señas, L

1997-04-14

A porphyrinic microsensor combined with in vivo voltammetry was used to monitor extracellular nitric oxide (NO) in the locus coeruleus (LC) of anaesthetized rats. Administration of N omega-nitro-L-arginine p-nitro-anilide (100 mg/kg, i.p) or 7-nitro indazole (30 mg/kg, i.p.), which both inhibit preferentially neuronal NO synthase (NOS), induced a marked decrease in the NO oxidation peak height. On the other hand, N omega-nitro-L-arginine methyl ester (L-NAME) (200 mg/kg, i.p.), a less selective NOS inhibitor, failed to decrease the NO signal. Moreover, intra LC administration of NMDA, known to activate LC noradrenergic neurones, increased the NO signal. This study demonstrates the usefulness of in vivo voltammetry to monitor basal levels of NO and their changes in the LC. Differential effects of NOS inhibitors show that their central activity need to be assessed through in situ measurement of NO before using these inhibitors as neuropharmacological tools.

CMOS image sensors as an efficient platform for glucose monitoring.

PubMed

Devadhasan, Jasmine Pramila; Kim, Sanghyo; Choi, Cheol Soo

2013-10-07

Complementary metal oxide semiconductor (CMOS) image sensors have been used previously in the analysis of biological samples. In the present study, a CMOS image sensor was used to monitor the concentration of oxidized mouse plasma glucose (86-322 mg dL(-1)) based on photon count variation. Measurement of the concentration of oxidized glucose was dependent on changes in color intensity; color intensity increased with increasing glucose concentration. The high color density of glucose highly prevented photons from passing through the polydimethylsiloxane (PDMS) chip, which suggests that the photon count was altered by color intensity. Photons were detected by a photodiode in the CMOS image sensor and converted to digital numbers by an analog to digital converter (ADC). Additionally, UV-spectral analysis and time-dependent photon analysis proved the efficiency of the detection system. This simple, effective, and consistent method for glucose measurement shows that CMOS image sensors are efficient devices for monitoring glucose in point-of-care applications.

Removal of organics and degradation products from industrial wastewater by a membrane bioreactor integrated with ozone or UV/H₂O₂ treatment.

PubMed

Laera, G; Cassano, D; Lopez, A; Pinto, A; Pollice, A; Ricco, G; Mascolo, G

2012-01-17

The treatment of a pharmaceutical wastewater resulting from the production of an antibacterial drug (nalidixic acid) was investigated employing a membrane bioreactor (MBR) integrated with either ozonation or UV/H(2)O(2) process. This was achieved by placing chemical oxidation in the recirculation stream of the MBR. A conventional configuration with chemical oxidation as polishing for the MBR effluent was also tested as a reference. The synergistic effect of MBR when integrated with chemical oxidation was assessed by monitoring (i) the main wastewater characteristics, (ii) the concentration of nalidixic acid, (iii) the 48 organics identified in the raw wastewater and (iv) the 55 degradation products identified during wastewater treatment. Results showed that MBR integration with ozonation or UV/H(2)O(2) did not cause relevant drawbacks to both biological and filtration processes, with COD removal rates in the range 85-95%. Nalidixic acid passed undegraded through the MBR and was completely removed in the chemical oxidation step. Although the polishing configuration appeared to give better performances than the integrated system in removing 15 out of 48 secondary organics while similar removals were obtained for 19 other compounds. The benefit of the integrated system was however evident for the removal of the degradation products. Indeed, the integrated system allowed higher removals for 34 out of 55 degradation products while for only 4 compounds the polishing configuration gave better performance. Overall, results showed the effectiveness of the integrated treatment with both ozone and UV/H(2)O(2).

Dynamic viscosity mapping of the oxidation of squalene aerosol particles.

PubMed

Athanasiadis, Athanasios; Fitzgerald, Clare; Davidson, Nicholas M; Giorio, Chiara; Botchway, Stanley W; Ward, Andrew D; Kalberer, Markus; Pope, Francis D; Kuimova, Marina K

2016-11-09

Organic aerosols (OAs) play important roles in multiple atmospheric processes, including climate change, and can impact human health. The physico-chemical properties of OAs are important for all these processes and can evolve through reactions with various atmospheric components, including oxidants. The dynamic nature of these reactions makes it challenging to obtain a true representation of their composition and surface chemistry. Here we investigate the microscopic viscosity of the model OA composed of squalene, undergoing chemical aging. We employ Fluorescent Lifetime Imaging Microscopy (FLIM) in conjunction with viscosity sensitive probes termed molecular rotors, in order to image the changes in microviscosity in real time during oxidation with ozone and hydroxyl radicals, which are two key oxidising species in the troposphere. We also recorded the Raman spectra of the levitated particles to follow the reactivity during particle ozonolysis. The levitation of droplets was achieved via optical trapping that enabled simultaneous levitation and measurement via FLIM or Raman spectroscopy and allowed the true aerosol phase to be probed. Our data revealed a very significant increase in viscosity of the levitated squalene droplets upon ozonolysis, following their transformation from the liquid to solid phase that was not observable when the oxidation was carried out on coverslip mounted droplets. FLIM imaging with sub-micron spatial resolution also revealed spatial heterogeneity in the viscosity distribution of oxidised droplets. Overall, a combination of molecular rotors, FLIM and optical trapping is able to provide powerful insights into OA chemistry and the microscopic structure that enables the dynamic monitoring of microscopic viscosity in aerosol particles in their true phase.

[Impact of periodical flooding-drying on nitrification and ammonia oxidizers in hydro-fluctuation belt of the Three Gorges Reservoir].

PubMed

Guo, Jia; Jiang, Xianjun; Zhou, Xue; Meng, Yao; Jia, Zhongjun

2016-06-04

This study was aimed to elucidate the effect of periodic flooding-drying to ecological processes of ammonia oxidizers in the hydro-fluctuation belt of the Three Gorges Reservoir. Soil samples were collected at thee altitudes in regions of Wanzhou, Fengdu and Changshou, representing 8, 5 and 0 times floodingdrying management, respectively. Soil physiochemical properties were analyzed and microcosms were constructed to monitor nitrification activity by fertilizing soils with ammonium substrate. Real-time PCR was used to quantify the population size of ammonia-oxidizing archaea (AOA) and bacteria (AOB). DGGE fingerprints and clone libraries were conducted to study the shift of AOA and AOB compositions in nitrifying soils. Among the physiochemical characteristics of the soils, soil organic matter and total phosphates increased along with cycle increasing. After incubation for 13 days, the net nitrification rates of the samples with 8 cycles exceeded those with 5 cycles. The quantities of both AOA and AOB have increased during the incubation. Phylogenetic analysis showed that AOA were placed within the soil group 1.1b and soil group 1.1a, while bacterial ammonia oxidizers were closely related to Nitrosospira and Cluster 0. Periodical flooding-drying increased soil organic matter, enhanced soil nitrification activity and likely played important roles in shaping community structures of soil ammonia oxidizers.

Individual Human Cell Responses to Low Doses of Chemicals and Radiation Studied by Synchrotron Infrared Spectromicroscopy

NASA Astrophysics Data System (ADS)

Martin, Michael C.; Holman, Hoi-Ying N.; Blakely, Eleanor A.; Goth-Goldstein, Regine; McKinney, Wayne R.

2000-03-01

Vibrational spectroscopy, when combined with synchrotron radiation-based (SR) microscopy, is a powerful new analytical tool with high spatial resolution for detecting biochemical changes in individual living cells. In contrast to other microscopy methods that require fixing, drying, staining or labeling, SR FTIR microscopy probes intact living cells providing a composite view of all of the molecular responses and the ability to monitor the responses over time in the same cell. Observed spectral changes include all types of lesions induced in that cell as well as cellular responses to external and internal stresses. These spectral changes combined with other analytical tools may provide a fundamental understanding of the key molecular mechanisms induced in response to stresses created by low-doses of radiation and chemicals. In this study we used high spatial-resolution SR FTIR vibrational spectromicroscopy at ALS Beamline 1.4.3 as a sensitive analytical tool to detect chemical- and radiation-induced changes in individual human cells. Our preliminary spectral measurements indicate that this technique is sensitive enough to detect changes in nucleic acids and proteins of cells treated with environmentally relevant concentrations of oxidative stresses: bleomycin, hydrogen peroxide, and X-rays. We observe spectral changes that are unique to each exogenous stressor. This technique has the potential to distinguish changes from exogenous or endogenous oxidative processes. Future development of this technique will allow rapid monitoring of cellular processes such as drug metabolism, early detection of disease, bio-compatibility of implant materials, cellular repair mechanisms, self assembly of cellular apparatus, cell differentiation and fetal development.

Bacterial Energy Sensor Aer Modulates the Activity of the Chemotaxis Kinase CheA Based on the Redox State of the Flavin Cofactor.

PubMed

Samanta, Dipanjan; Widom, Joanne; Borbat, Peter P; Freed, Jack H; Crane, Brian R

2016-12-09

Flagellated bacteria modulate their swimming behavior in response to environmental cues through the CheA/CheY signaling pathway. In addition to responding to external chemicals, bacteria also monitor internal conditions that reflect the availability of oxygen, light, and reducing equivalents, in a process termed "energy taxis." In Escherichia coli, the transmembrane receptor Aer is the primary energy sensor for motility. Genetic and physiological data suggest that Aer monitors the electron transport chain through the redox state of its FAD cofactor. However, direct biochemical data correlating FAD redox chemistry with CheA kinase activity have been lacking. Here, we test this hypothesis via functional reconstitution of Aer into nanodiscs. As purified, Aer contains fully oxidized FAD, which can be chemically reduced to the anionic semiquinone (ASQ). Oxidized Aer activates CheA, whereas ASQ Aer reversibly inhibits CheA. Under these conditions, Aer cannot be further reduced to the hydroquinone, in contrast to the proposed Aer signaling model. Pulse ESR spectroscopy of the ASQ corroborates a potential mechanism for signaling in that the resulting distance between the two flavin-binding PAS (Per-Arnt-Sim) domains implies that they tightly sandwich the signal-transducing HAMP domain in the kinase-off state. Aer appears to follow oligomerization patterns observed for related chemoreceptors, as higher loading of Aer dimers into nanodiscs increases kinase activity. These results provide a new methodological platform to study Aer function along with new mechanistic details into its signal transduction process. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

The zinc stable isotope signature of waste rock drainage in Arctic Canada

NASA Astrophysics Data System (ADS)

Matthies, Romy; Blowes, David

2014-05-01

Leachate emerging from a pilot-scale waste rock pile of the Diavik diamond mine, Northwest Territories, was monitored. The well-characterized waste rock consists of granite, pegmatitic granite and biotite schist with an average total sulfur and carbonate carbon concentration of 0.053 and 0.027 wt. %, respectively. During the field seasons of 2011 and 2012, the Zn stable isotope footprint was characterized alongside standard monitoring parameters. pH ranged between 4.3 and 6.8 and carbonate alkalinity was low or undetectable. Al and Fe concentrations averaged 6.78 mg L-1 and 175 µg L-1, respectively. The pH and metal mobility were governed by sulfide oxidation and sorption and co-precipitation onto iron and aluminium hydroxides. The main processes controlling zinc mobility in the range of 0.4 and 4.7 mg L-1 was the oxidative dissolution of sphalerite (ZnS) in the biotite schist and the attenuation of zinc onto secondary iron and aluminium hydroxides and desorption upon the pH declining below the pHpzc. The isotope ratios between -0.16 and +0.19 ‰ (δ66Zn, avg = +0.05 ‰, n = 43) are consistent with values reported from other sphalerite containing deposits. Zn isotope ratios and concentrations were largely uncorrelated suggesting that the processes affecting Zn mobility had little or no impact on the Zn isotope signature. Data indicate, that the Zn isotope ratios of the waste rock leachate may be used as a fingerprint to track anthropogenic, mine-derived Zn sources under varying environmental conditions.

Evaluation of an electronic nose for odorant and process monitoring of alkaline-stabilized biosolids production.

PubMed

Romero-Flores, Adrian; McConnell, Laura L; Hapeman, Cathleen J; Ramirez, Mark; Torrents, Alba

2017-11-01

Electronic noses have been widely used in the food industry to monitor process performance and quality control, but use in wastewater and biosolids treatment has not been fully explored. Therefore, we examined the feasibility of an electronic nose to discriminate between treatment conditions of alkaline stabilized biosolids and compared its performance with quantitative analysis of key odorants. Seven lime treatments (0-30% w/w) were prepared and the resultant off-gas was monitored by GC-MS and by an electronic nose equipped with ten metal oxide sensors. A pattern recognition model was created using linear discriminant analysis (LDA) and principal component analysis (PCA) of the electronic nose data. In general, LDA performed better than PCA. LDA showed clear discrimination when single tests were evaluated, but when the full data set was included, discrimination between treatments was reduced. Frequency of accurate recognition was tested by three algorithms with Euclidan and Mahalanobis performing at 81% accuracy and discriminant function analysis at 70%. Concentrations of target compounds by GC-MS were in agreement with those reported in literature and helped to elucidate the behavior of the pattern recognition via comparison of individual sensor responses to different biosolids treatment conditions. Results indicated that the electronic nose can discriminate between lime percentages, thus providing the opportunity to create classes of under-dosed and over-dosed relative to regulatory requirements. Full scale application will require careful evaluation to maintain accuracy under variable process and environmental conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Silver-Ion Solid Phase Extraction Separation of Classical, Aromatic, Oxidized, and Heteroatomic Naphthenic Acids from Oil Sands Process-Affected Water.

PubMed

Huang, Rongfu; Chen, Yuan; Gamal El-Din, Mohamed

2016-06-21

The separation of classical, aromatic, oxidized, and heteroatomic (sulfur-containing) naphthenic acid (NA) species from unprocessed and ozone-treated oil sands process-affected water (OSPW) was performed using silver-ion (Ag-ion) solid phase extraction (SPE) without the requirement of pre-methylation for NAs. OSPW samples before SPE and SPE fractions were characterized using ultra performance liquid chromatography ion mobility time-of-flight mass spectrometry (UPLC-IM-TOFMS) to corroborate the separation of distinct NA species. The mass spectrum identification applied a mass tolerance of ±1.5 mDa due to the mass errors of NAs were measured within this range, allowing the identification of O2S-NAs from O2-NAs. Moreover, separated NA species facilitated the tandem mass spectrometry (MS/MS) characterization of NA compounds due to the removal of matrix and a simplified composition. MS/MS results showed that classical, aromatic, oxidized, and sulfur-containing NA compounds were eluted into individual SPE fractions. Overall results indicated that the separation of NA species using Ag-ion SPE is a valuable method for extracting individual NA species that are of great interest for environmental toxicology and wastewater treatment research, to conduct species-specific studies. Furthermore, the separated NA species on the milligram level could be widely used as the standard materials for environmental monitoring of NAs from various contamination sites.

Mechanistic studies of the CO-oxidation reaction on catalysts for use in long-life CO2 lasers

NASA Technical Reports Server (NTRS)

Dawood, Talat; Richmond, John R.; Riley, Brian W.

1990-01-01

The catalytic recombination of carbon monoxide and oxygen was studied under conditions expected to be present in a sealed E-beam CO2 laser system. These conditions are typically a gas inlet temperature of 60 C, a substoichiometric CO/O2 ratio of ca. 2.5/1 with an oxygen feed rate of ca. 5 micromoles/s, a carrier gas comprising He, N2 and CO2 in the ratio of 3:2:1, near atmospheric pressure and a gas velocity of 4 m/s. Heterogeneous catalysts, based on precious metal supported on tin oxide, have been coated onto ceramic monoliths and tested for catalytic activity and stability after a reduction/passivation step. Two catalyst systems have been chosen. These are Pt/Pd/SnO2 and Pt/Ru/SnO2. Under the conditions described above, a characteristic decline in catalytic activity is apparent for both systems, and exit gas temperature has been recognized as a sensitive parameter by which to monitor the activity changes. A semilogarithmic plot of exit temperature as a function of time has revealed two distinct processes connected with the decline in activity: one process is associated with reduction of the oxidized precious metal (at Site A), whilst the other is related to the formation and approach to steady-state of an active site at the metal/support interface (Site B).

Environmental monitoring of brominated flame retardants

NASA Astrophysics Data System (ADS)

Vagula, Mary C.; Kubeldis, Nathan; Nelatury, Charles F.

2011-06-01

Brominated flame retardants (BFRs) are synthetic organobromide compounds which inhibit ignition and combustion processes. Because of their immense ability to retard fire and save life and property, they have been extensively used in many products such as TVs, computers, foam, plastics etc. The five major classes of BFRs are tetrabromobisphenol-A (TBBPA), hexabromocyclododecane (HBCD), pentabromodiphenyl ether, octabromodiphenyl ether, and decabromodiphenyl ether. The last three are also commonly called PBDEs. BDE-85 and BDE-209 are the two prominent congeners of PBDEs and this study reports the adverse effects of these congeners in rodents. Exposure of rat sciatic nerves to 5 μg/mL and 20 μg/mL of BDE-85 and BDE-209 respectively lead to significant, concentration dependent reduction in nerve conduction function. Glucose absorption in the rat intestinal segments exposed to 5 μg/mL of BDE-85 and BDE-209 was significantly reduced for both the compounds tested. Lastly, mice when exposed to 0.25 mg/kg body weight for four days showed a disruption in oxidant and antioxidant equilibrium. The tissues namely liver and brain have shown increase in the levels of lipid hydroperoxides indicating oxidative stress. Moreover, all the protective enzymes namely superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase, and glutathione S transferase (GST) have shown tissue specific alterations indicating the induction of damaging oxidative stress and setting in of lipid peroxidation in exposed animals. The results indicate monitoring of PBDEs in the environment is essential because levels as low as 5 μg/mL and 0.25 mg/kg body weight were able to cause damage to the functions of rodents.

Small molecules as tracers in atmospheric secondary organic aerosol

NASA Astrophysics Data System (ADS)

Yu, Ge

Secondary organic aerosol (SOA), formed from in-air oxidation of volatile organic compounds, greatly affects human health and climate. Although substantial research has been devoted to SOA formation and evolution, the modeled and lab-generated SOA are still low in mass and degree of oxidation compared to ambient measurements. In order to compensate for these discrepancies, the aqueous processing pathway has been brought to attention. The atmospheric waters serve as aqueous reaction media for dissolved organics to undergo further oxidation, oligomerization, or other functionalization reactions, which decreases the vapor pressure while increasing the oxidation state of carbon atoms. Field evidence for aqueous processing requires the identification of tracer products such as organosulfates. We synthesized the standards for two organosulfates, glycolic acid sulfate and lactic acid sulfate, in order to measure their aerosol-state concentration from five distinct locations via filter samples. The water-extracted filter samples were analyzed by LC-MS. Lactic acid sulfate and glycolic acid sulfate were detected in urban locations in the United States, Mexico City, and Pakistan with varied concentrations, indicating their potential as tracers. We studied the aqueous processing reaction between glyoxal and nitrogen-containing species such as ammonium and amines exclusively by NMR spectrometry. The reaction products formic acid and several imidazoles along with the quantified kinetics were reported. The brown carbon generated from these reactions were quantified optically by UV-Vis spectroscopy. The organic-phase reaction between oxygen molecule and alkenes photosensitized by alpha-dicarbonyls were studied in the same manner. We observed the fast kinetics transferring alkenes to epoxides under simulated sunlight. Statistical estimations indicate a very effective conversion of aerosol-phase alkenes to epoxides, potentially forming organosulfates in a deliquescence event and increasing aerosol mass. Finally, we built a containerless apparatus to study aqueous processing reactions using an acoustic levitator paired with a mass spectrometer. The levitator is capable of trapping droplets with the size of 80-500 mum in diameter for over eight hours. The apparatus is also capable of drying and wetting the droplet in a controllable manner. We performed am example reaction between glyoxal and ammonium sulfate using this instrument, and showed that it could qualitatively monitor aqueous processing reactions.

Oxidative Stress in Kidney Diseases: The Cause or the Consequence?

PubMed

Krata, Natalia; Zagożdżon, Radosław; Foroncewicz, Bartosz; Mucha, Krzysztof

2018-06-01

Exaggerated oxidative stress (OS) is usually considered as a disturbance in regular function of an organism. The excessive levels of OS mediators may lead to major damage within the organism's cells and tissues. Therefore, the OS-associated biomarkers may be considered as new diagnostic tools of various diseases. In nephrology, researchers are looking for alternative methods replacing the renal biopsy in patients with suspicion of chronic kidney disease (CKD). Currently, CKD is a frequent health problem in world population, which can lead to progressive loss of kidney function and eventually to end-stage renal disease. The course of CKD depends on the primary disease. It is assumed that one of the factors influencing the course of CKD might be OS. In the current work, we review whether monitoring the OS-associated biomarkers in nephrology patients can support the decision-making process regarding diagnosis, prognostication and treatment initiation.

Role of the carbonate impurities on the surface state of pyrite and arsenopyrite under treatment by high power electromagnetic pulses (HPEMP): oxidation of 50-100 μm size particles

NASA Astrophysics Data System (ADS)

Filippova, I.; Chanturiya, V.; Filippov, L.; Ryazantseva, M.; Bunin, I.

2013-03-01

Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) and Transmission Electron Microscopy (TEM) have shown the variation of surface phase compositions of carbonate bearing pyrite and arsenopyrite as a result of the combined action of chemical oxidation and thermal processes after the treatment by high power electromagnetic pulses (HPEMP). The monitoring of the surface phase composition allowed to determine the correlation between the treatment conditions, the surface phase composition, and the flotation yield. Thus, HPEMP treatment may be regarded as a tool controlling the surface composition and the sorption ability of flotation collector onto minerals surface, and therefore, allowing to control the hydrophobic-hydrophilic surface balance. It was confirmed in this study that the flotation of pyrite with xanthate as a result of the influence HPEMP may vary depending on the presence of impurities such as calcite.

Intrinsic Chemiluminescence Generation during Advanced Oxidation of Persistent Halogenated Aromatic Carcinogens.

PubMed

Mao, Li; Liu, Yu-Xiang; Huang, Chun-Hua; Gao, Hui-Ying; Kalyanaraman, Balaraman; Zhu, Ben-Zhan

2015-07-07

The ubiquitous distribution coupled with their carcinogenicity has raised public concerns on the potential risks to both human health and the ecosystem posed by the halogenated aromatic compounds (XAr). Recently, advanced oxidation processes (AOPs) have been increasingly favored as an "environmentally-green" technology for the remediation of such recalcitrant and highly toxic XAr. Here, we show that AOPs-mediated degradation of the priority pollutant pentachlorophenol and all other XAr produces an intrinsic chemiluminescence that directly depends on the generation of the extremely reactive hydroxyl radicals. We propose that the hydroxyl radical-dependent formation of quinoid intermediates and electronically excited carbonyl species is responsible for this unusual chemiluminescence production. A rapid, sensitive, simple, and effective chemiluminescence method was developed to quantify trace amounts of XAr and monitor their real-time degradation kinetics. These findings may have broad biological and environmental implications for future research on this important class of halogenated persistent organic pollutants.

Simultaneous dynamic optical and electrical properties of endothelial cell attachment on indium tin oxide bioelectrodes.

PubMed

Choi, Chang K; English, Anthony E; Kihm, Kenneth D; Margraves, Charles H

2007-01-01

This study quantifies the dynamic attachment and spreading of porcine pulmonary artery endothelial cells (PPAECs) on optically thin, indium tin oxide (ITO) biosensors using simultaneous differential interference contrast microscopy (DICM) and electrical microimpedance spectroscopy. A lock-in amplifier circuit monitored the impedance of PPAECs cultivated on the transparent ITO bioelectrodes as a function of frequency between 10 Hz and 100 kHz and as a function of time, while DICM images were simultaneously acquired. A digital image processing algorithm quantified the cell-covered electrode area as a function of time. The results of this study show that the fraction of the cell-covered electrode area is in qualitative agreement with the electrical impedance during the attachment phase following the cell settling on the electrode surface. The possibility of several distinctly different states of electrode coverage and cellular attachment giving rise to similar impedance signals is discussed.

Enhanced Air Stability in REPb3 (RE = Rare Earths) by Dimensional Reduction Mediated Valence Transition.

PubMed

Subbarao, Udumula; Sarkar, Sumanta; Jana, Rajkumar; Bera, Sourav S; Peter, Sebastian C

2016-06-06

We conceptually selected the compounds REPb3 (RE = Eu, Yb), which are unstable in air, and converted them to the stable materials in ambient conditions by the chemical processes of "nanoparticle formation" and "dimensional reduction". The nanoparticles and the bulk counterparts were synthesized by the solvothermal and high-frequency induction furnace heating methods, respectively. The reduction of the particle size led to the valence transition of the rare earth atom, which was monitored through magnetic susceptibility and X-ray absorption near edge spectroscopy (XANES) measurements. The stability was checked by X-ray diffraction and thermogravimetric analysis over a period of seven months in oxygen and argon atmospheres and confirmed by XANES. The nanoparticles showed outstanding stability toward aerial oxidation over a period of seven months compared to the bulk counterpart, as the latter one is more prone to the oxidation within a few days.

Degradation of some representative polycyclic aromatic hydrocarbons by the water-soluble protein extracts from Zea mays L. cv PR32-B10.

PubMed

Barone, Roberto; de Biasi, Margherita-Gabriella; Piccialli, Vincenzo; de Napoli, Lorenzo; Oliviero, Giorgia; Borbone, Nicola; Piccialli, Gennaro

2016-10-01

The ability of the water-soluble protein extracts from Zea mais L. cv. PR32-B10 to degrade some representative polycyclic aromatic hydrocarbons (PAHs), has been evaluated. Surface sterilized seeds of corn (Zea mais L. Pioneer cv. PR32-B10) were hydroponically cultivated in a growth chamber under no-stressful conditions. The water-soluble protein extracts isolated from maize tissues showed peroxidase, polyphenol oxidase and catalase activities. Incubation of the extracts with naphthalene, fluorene, phenanthrene and pyrene, led to formation of oxidized and/or degradation products. GC-MS and TLC monitoring of the processes showed that naphthalene, phenanthrene, fluorene and pyrene underwent 100%, 78%, 92% and 65% oxidative degradation, respectively, after 120 min. The chemical structure of the degradation products were determined by (1)H NMR and ESI-MS spectrometry. Copyright © 2016 Elsevier Ltd. All rights reserved.

Analysis of the measured effects of the principal exhaust effluents from solid rocket motors

NASA Technical Reports Server (NTRS)

Dawbarn, R.; Kinslow, M.; Watson, D. J.

1980-01-01

The feasibility of conducting environmental chamber tests using a small rocket motor to study the physical processes which occur when the exhaust products from solid motors mix with the ambient atmosphere was investigated. Of particular interest was the interaction between hydrogen chloride, aluminum oxide, and water vapor. Several types of instruments for measuring HCl concentrations were evaluated. Under some conditions it was noted that acid aerosols were formed in the ground cloud. These droplets condensed on Al2O3 nuclei and were associated with the rocket exhaust cooling during the period of plume rise to stabilization. Outdoor firings of the solid rocket motors of a 6.4 percent scaled model of the space shuttle were monitored to study the interaction of the exhaust effluents with vegetation downwind of the test site. Data concerning aluminum oxide particles produced by solid rocket motors were evaluated.

Development of Advanced Low Conductivity Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Zhu, Dong-Ming; Miller, Robert A.

2004-01-01

Advanced multi-component, low conductivity oxide thermal barrier coatings have been developed using an approach that emphasizes real-time monitoring of thermal conductivity under conditions that are engine-like in terms of temperatures and heat fluxes. This is in contrast to the traditional approach where coatings are initially optimized in terms of furnace and burner rig durability with subsequent measurement in the as-processed or furnace-sintered condition. The present work establishes a laser high-heat-flux test as the basis for evaluating advanced plasma-sprayed and electron beam-physical vapor deposited (EB-PVD) thermal barrier coatings under the NASA Ultra-Efficient Engine Technology (UEET) Program. The candidate coating materials for this program are novel thermal barrier coatings that are found to have significantly reduced thermal conductivities and improved thermal stability due to an oxide-defect-cluster design. Critical issues for designing advanced low conductivity coatings with improved coating durability are also discussed.

Biosensors based on inorganic nanoparticles with biomimetic properties: Biomedical applications and in vivo cytotoxicity measurements

NASA Astrophysics Data System (ADS)

Ispas, Cristina R.

The rapid progress of nanotechnology and advanced nanomaterials production offer significant opportunities for designing powerful biosensing devices with enhanced performances. This thesis introduces ceria (CeO 2) nanoparticles and its congeners as a new class of materials with huge potential in bioanalytical and biosensing applications. Unique redox, catalytic and oxygen storage/release properties of ceria nanoparticles, originating from their dual oxidation state are used to design biomedical sensors with high sensitivity and low oxygen dependency. This thesis describes a new approach for fabrication of implantable microbiosensors designed for monitoring neurological activity in physiological conditions. Understanding the mechanisms involved in neurological signaling and functioning is of great physiological importance. In this respect, the development of effective methods that allow accurate detection and quantification of biological analytes (i.e. L-glutamate and glucose) associated with neurological processes is of paramount importance. The performance of most analytical techniques currently used to monitor L-glutamate and glucose is suboptimal and only a limited number of approaches address the problem of operation in oxygen-restricted conditions, such as ischemic brain injury. Over the past couple of years, enzyme based biosensors have been used to investigate processes related to L-glutamate release/uptake and the glucose cycle within the brain. However, most of these sensors, based on oxidoreductase enzymes, do not work in conditions of limited oxygen availability. This thesis presents the development of a novel sensing technology for the detection of L-glutamate and glucose in conditions of oxygen deprivation. This technology provides real-time assessment of the concentrations of these analytes with high sensitivity, wide linear range, and low oxygen dependence. The fabrication, characterization and optimization of enzyme microbiosensors are discussed. This work introduces a new generic approach of improving the sensitivity of oxidase-based enzymatic assays and indicates that ceria and its mixture with other metal oxide nanoparticles could be used to minimize the problems associated with variations of the oxygen. These materials have great potential in bioanalytical and biotechnological applications and offer great opportunities for development of implantable sensing devices for in vivo and in vitro monitoring of analytes of clinical relevance. Additionally, this thesis evaluates the toxicity of different metal and metal oxide nanoparticles by using zebrafish embryos as a toxicological target. Because of their similarities with other vertebrates, rapid development and low cost, zebrafish embryos are ideal animal models for probing toxicological effects of engineered nanomaterials. Among the nanomaterials tested, nickel nanoparticles were characterized by high toxicity and induced delayed development and morphological malformations, while metal oxides nanoparticles (i.e. ceria nanoparticles) had no toxic effects.

Monitoring plasma treatment of thin films by surface plasmon resonance

NASA Astrophysics Data System (ADS)

Laha, Ranjit; Manivannan, A.; Kasiviswanathan, S.

2014-03-01

We report the surface plasmon resonance (SPR) measurements during plasma treatment of thin films by an indigenously designed setup. From the measurements on Al (6.3 nm)/Ag (38 nm) bi-layer at a pressure of 0.02 mbar, the SPR position was found to be shifted by ˜20° after a plasma treatment of ˜7 h. The formation of oxide layers during plasma oxidation was confirmed by glancing angle x-ray diffraction (GXRD) measurements. Combined analysis of GXRD and SPR data confirmed that while top Al layer enables controlling plasma oxidation of Ag, the setup enables monitoring the same. The setup designed is a first of its kind for in situ SPR studies where creation of low pressure is a prerequisite.

Monitoring plasma treatment of thin films by surface plasmon resonance.

PubMed

Laha, Ranjit; Manivannan, A; Kasiviswanathan, S

2014-03-01

We report the surface plasmon resonance (SPR) measurements during plasma treatment of thin films by an indigenously designed setup. From the measurements on Al (6.3 nm)/Ag (38 nm) bi-layer at a pressure of 0.02 mbar, the SPR position was found to be shifted by ~20° after a plasma treatment of ~7 h. The formation of oxide layers during plasma oxidation was confirmed by glancing angle x-ray diffraction (GXRD) measurements. Combined analysis of GXRD and SPR data confirmed that while top Al layer enables controlling plasma oxidation of Ag, the setup enables monitoring the same. The setup designed is a first of its kind for in situ SPR studies where creation of low pressure is a prerequisite.

Low resistance AL2O3 magnetic tunnel junctions optimized through in situ conductance measurements

NASA Astrophysics Data System (ADS)

Wolfman, J.; Mauri, D.; Lin, T.; Yang, J.; Chen, T.

2005-06-01

In situ electrical conductance is used to monitor the growth and natural oxidation of aluminum on top of a CoFe electrode. Light oxidation is found to enhance the electron specular scattering of the CoFe/vacuum interface. Aluminum deposited onto CoFe intermixes to a depth of a few atomic layers, however, subsequent natural oxidation tends to reverse this interdiffusion through oxygen-driven A1 segregation. At the right A1 thickness, natural oxidation creates a clean and specular CoFe /AlOx interface very similar to the best achievable CoFe/vacuum interface. For thicker A1, natural oxidation leaves behind underoxidized AlOx and most importantly an interdiffused CoFe /Al interface. Using 2Torr×150-s natural oxidation, we have fabricated magnetic tunnel junctions (MTJs) with a peak tunnel magnetoresistance (TMR) of 18% for a resistance area product of 7Ωμm2, at the A1 metal thickness of 6 Å. With the same oxidation process TMR drops to only 8% when A1 is increased to 9 Å. Contrary to the accepted view, we do not attribute this TMR drop to A1 underoxidation, but primarily to the interdiffusion at the CoFe /Al interface. This assertion is strongly supported by a second set of MTJs differing only by the insertion of a nano-oxide layer (NOL) on top of CoFe. In this case when Al is increased from 6 to 9 Å, the TMR does not drop but increases from 16% to 27%. This is significant because NOL is found to effectively prevent Al diffusion into CoFe. NOL is also found to act as a reservoir of oxygen, which is subsequently consumed by Al.

Aqueous-phase oxidation of green leaf volatiles by hydroxyl radical as a source of SOA: Product identification from methyl jasmonate and methyl salicylate oxidation

NASA Astrophysics Data System (ADS)

Hansel, Amie K.; Ehrenhauser, Franz S.; Richards-Henderson, Nicole K.; Anastasio, Cort; Valsaraj, Kalliat T.

2015-02-01

Green leaf volatiles (GLVs) are a group of biogenic volatile organic compounds (BVOCs) released into the atmosphere by vegetation. BVOCs produce secondary organic aerosol (SOA) via gas-phase reactions, but little is known of their aqueous-phase oxidation as a source of SOA. GLVs can partition into atmospheric water phases, e.g., fog, mist, dew or rain, and be oxidized by hydroxyl radicals (˙OH). These reactions in the liquid phase also lead to products that have higher molecular weights, increased polarity, and lower vapor pressures, ultimately forming SOA after evaporation of the droplet. To examine this process, we investigated the aqueous, ˙OH-mediated oxidation of methyl jasmonate (MeJa) and methyl salicylate (MeSa), two GLVs that produce aqueous-phase SOA. High performance liquid chromatography/electrospray ionization mass spectrometry (HPLC-ESI-MS) was used to monitor product formation. The oxidation products identified exhibit higher molecular mass than their parent GLV due to either dimerization or the addition of oxygen and hydroxyl functional groups. The proposed structures of potential products are based on mechanistic considerations combined with the HPLC/ESI-MS data. Based on the structures, the vapor pressure and the Henry's law constant were estimated with multiple methods (SPARC, SIMPOL, MPBPVP, Bond and Group Estimations). The estimated vapor pressures of the products identified are significantly (up to 7 orders of magnitude) lower than those of the associated parent compounds, and therefore, the GLV oxidation products may remain as SOA after evaporation of the water droplet. The contribution of the identified oxidation products to SOA formation is estimated based on measured HPLC-ESI/MS responses relative to previous aqueous SOA mass yield measurements.

New Photosensitized Processes at Aerosol and Ocean Surfaces

NASA Astrophysics Data System (ADS)

Rossignol, S.; Aregahegn, K. Z.; Ciuraru, R.; Bernard, F.; Tinel, L.; Fine, L.; George, C.

2014-12-01

From a few years now, there is a growing body of evidence that photoinduced processes could be of great importance for the tropospheric chemistry. Here, we would like to present two additional outcomes of this new area of research, firstly the photosensitized direct VOC uptake by aerosols and, secondly, the photoinduced chemical formation of unsaturated VOC from marine microlayer proxy. It was recently shown that the chemistry of glyoxal toward ammonium ions into droplets and wet aerosols leads to the formation of light-absorbing compounds. Among them, we found that imidazole-2-carboxaldehyde (IC) acts as a photosensitizer and is able to initiate the growth of organic aerosols via the uptake of VOC, such as limonene. Given its potential importance, the mechanism of this photoinduced uptake was investigated thanks to aerosol flow tube experiments and UPLC-ESI-HRMS analysis. Results reveal hydrogen abstraction on the VOC molecule by the triplet state of IC leading to the VOC oxidation without any traditional oxidant. As well as aerosol, the sea-surface microlayer, known to be enriched in light-absorbing organics, is largely impacted by photochemical processes. Recent studies have pointed out for example the role of photosentitized processes in the loss of NO2 and ozone at water surfaces containing photoactive compounds such as chlorophyll. In order to go further, we worked from sea-surface microlayer proxy containing humic acids as photoactive material and organic acids as surfactants. Beside oxidation processes, we monitored by high resolution PTR-MS the release in the gas phase of unsaturated compounds, including C5 dienes (isoprene ?). A strong correlation between the measured surface tension and the C5 diene concentration in the gas phase was evidenced, clearly pointing toward an interfacial process. This contribution will highlight the similarities between both systems and will attempt to present a general chemical scheme for photosensitized chemistry at interfaces.

Photoacoustic Spectroscopy with Quantum Cascade Lasers for Trace Gas Detection

PubMed Central

Elia, Angela; Di Franco, Cinzia; Lugarà, Pietro Mario; Scamarcio, Gaetano

2006-01-01

Various applications, such as pollution monitoring, toxic-gas detection, non invasive medical diagnostics and industrial process control, require sensitive and selective detection of gas traces with concentrations in the parts in 109 (ppb) and sub-ppb range. The recent development of quantum-cascade lasers (QCLs) has given a new aspect to infrared laser-based trace gas sensors. In particular, single mode distributed feedback QCLs are attractive spectroscopic sources because of their excellent properties in terms of narrow linewidth, average power and room temperature operation. In combination with these laser sources, photoacoustic spectroscopy offers the advantage of high sensitivity and selectivity, compact sensor platform, fast time-response and user friendly operation. This paper reports recent developments on quantum cascade laser-based photoacoustic spectroscopy for trace gas detection. In particular, different applications of a photoacoustic trace gas sensor employing a longitudinal resonant cell with a detection limit on the order of hundred ppb of ozone and ammonia are discussed. We also report two QC laser-based photoacoustic sensors for the detection of nitric oxide, for environmental pollution monitoring and medical diagnostics, and hexamethyldisilazane, for applications in semiconductor manufacturing process.

Monitoring long-range electron transfer pathways in proteins by stimulated attosecond broadband X-ray Raman spectroscopy

DOE PAGES

Zhang, Yu; Biggs, Jason D.; Govind, Niranjan; ...

2014-10-09

In this study, long-range electron transfer (ET) plays a key role in many biological energy conversion and synthesis processes. We show that nonlinear spectroscopy with attosecond X-ray pulses provides a real time movie of the evolving oxidation states and electron densities around atoms, and can probe these processes with high spatial and temporal resolution. This is demonstrated in a simulation study of the stimulated X-ray Raman (SXRS) signals in Re-modified azurin, which had long served as a benchmark for long-range ET in proteins. Nonlinear SXRS signals are sensitive to the local electronic structure and should offer a novel window formore » long-range ET.« less

40 CFR 98.194 - Monitoring and QA/QC requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... Association (incorporated by reference—see § 98.7). (d) You must use the analysis of calcium oxide and magnesium oxide content of each lime product that is produced and that is collected during the same month as...

Flexible and wearable electronic silk fabrics for human physiological monitoring

NASA Astrophysics Data System (ADS)

Mao, Cuiping; Zhang, Huihui; Lu, Zhisong

2017-09-01

The development of textile-based devices for human physiological monitoring has attracted tremendous interest in recent years. However, flexible physiological sensing elements based on silk fabrics have not been realized. In this paper, ZnO nanorod arrays are grown in situ on reduced graphene oxide-coated silk fabrics via a facile electro-deposition method for the fabrication of silk-fabric-based mechanical sensing devices. The data show that well-aligned ZnO nanorods with hexagonal wurtzite crystalline structures are synthesized on the conductive silk fabric surface. After magnetron sputtering of gold electrodes, silk-fabric-based devices are produced and applied to detect periodic bending and twisting. Based on the electric signals, the deformation and release processes can be easily differentiated. Human arterial pulse and respiration can also be real-time monitored to calculate the pulse rate and respiration frequency, respectively. Throat vibrations during coughing and singing are detected to demonstrate the voice recognition capability. This work may not only help develop silk-fabric-based mechanical sensing elements for potential applications in clinical diagnosis, daily healthcare monitoring and voice recognition, but also provide a versatile method for fabricating textile-based flexible electronic devices.

40 CFR 63.9306 - What are my continuous parameter monitoring system (CPMS) installation, operation, and...

Code of Federal Regulations, 2010 CFR

2010-07-01

... section for each gas temperature monitoring device. (i) Locate the temperature sensor in a position that... temperature sensor system from electromagnetic interference and chemical contaminants. (iv) If a gas...) of this section. (1) For a thermal oxidizer, install a gas temperature monitor in the firebox of the...

40 CFR 63.9306 - What are my continuous parameter monitoring system (CPMS) installation, operation, and...

Code of Federal Regulations, 2011 CFR

2011-07-01

... section for each gas temperature monitoring device. (i) Locate the temperature sensor in a position that... temperature sensor system from electromagnetic interference and chemical contaminants. (iv) If a gas...) of this section. (1) For a thermal oxidizer, install a gas temperature monitor in the firebox of the...

40 CFR 62.15175 - What continuous emission monitoring systems must I install for gaseous pollutants?

Code of Federal Regulations, 2010 CFR

2010-07-01

..., maintain, and operate continuous emission monitoring systems for oxygen (or carbon dioxide), sulfur dioxide, and carbon monoxide. If you operate a Class I municipal waste combustion unit, also install, calibrate... emission monitoring system for sulfur dioxide, nitrogen oxides, and oxygen (or carbon dioxide) at the...

40 CFR 60.1720 - What continuous emission monitoring systems must I install for gaseous pollutants?

Code of Federal Regulations, 2011 CFR

2011-07-01

..., maintain, and operate continuous emission monitoring systems for oxygen (or carbon dioxide), sulfur dioxide, and carbon monoxide. If you operate a Class I municipal waste combustion unit, also install, calibrate... emission monitoring systems for sulfur dioxide, nitrogen oxides, and oxygen (or carbon dioxide) at the...

40 CFR 60.1720 - What continuous emission monitoring systems must I install for gaseous pollutants?

Code of Federal Regulations, 2010 CFR

2010-07-01

..., maintain, and operate continuous emission monitoring systems for oxygen (or carbon dioxide), sulfur dioxide, and carbon monoxide. If you operate a Class I municipal waste combustion unit, also install, calibrate... emission monitoring systems for sulfur dioxide, nitrogen oxides, and oxygen (or carbon dioxide) at the...

40 CFR 62.15175 - What continuous emission monitoring systems must I install for gaseous pollutants?

Code of Federal Regulations, 2011 CFR

2011-07-01

..., maintain, and operate continuous emission monitoring systems for oxygen (or carbon dioxide), sulfur dioxide, and carbon monoxide. If you operate a Class I municipal waste combustion unit, also install, calibrate... emission monitoring system for sulfur dioxide, nitrogen oxides, and oxygen (or carbon dioxide) at the...

40 CFR 60.1725 - How are the data from the continuous emission monitoring systems used?

Code of Federal Regulations, 2013 CFR

2013-07-01

... emission monitoring systems used? 60.1725 Section 60.1725 Protection of Environment ENVIRONMENTAL... Before August 30, 1999 Model Rule-Continuous Emission Monitoring § 60.1725 How are the data from the... systems for sulfur dioxide, nitrogen oxides, and carbon monoxide to demonstrate continuous compliance with...

40 CFR 60.1725 - How are the data from the continuous emission monitoring systems used?

Code of Federal Regulations, 2014 CFR

2014-07-01

... emission monitoring systems used? 60.1725 Section 60.1725 Protection of Environment ENVIRONMENTAL... Before August 30, 1999 Model Rule-Continuous Emission Monitoring § 60.1725 How are the data from the... systems for sulfur dioxide, nitrogen oxides, and carbon monoxide to demonstrate continuous compliance with...

40 CFR 60.1725 - How are the data from the continuous emission monitoring systems used?

Code of Federal Regulations, 2012 CFR

2012-07-01

... emission monitoring systems used? 60.1725 Section 60.1725 Protection of Environment ENVIRONMENTAL... Before August 30, 1999 Model Rule-Continuous Emission Monitoring § 60.1725 How are the data from the... systems for sulfur dioxide, nitrogen oxides, and carbon monoxide to demonstrate continuous compliance with...

40 CFR 63.364 - Monitoring requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... complying with § 63.363(b) or (d) through the use of an acid-water scrubber, the owner or operator shall... § 63.364(e) or continuously monitor and record the oxidation temperature at the outlet to the catalyst bed or at the exhaust point from the thermal combustion chamber using the temperature monitor...

40 CFR 63.364 - Monitoring requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... complying with § 63.363(b) or (d) through the use of an acid-water scrubber, the owner or operator shall... § 63.364(e) or continuously monitor and record the oxidation temperature at the outlet to the catalyst bed or at the exhaust point from the thermal combustion chamber using the temperature monitor...

40 CFR 63.364 - Monitoring requirements.

Code of Federal Regulations, 2011 CFR

2011-07-01

... with § 63.363(b) or (d) through the use of an acid-water scrubber, the owner or operator shall either... § 63.364(e) or continuously monitor and record the oxidation temperature at the outlet to the catalyst bed or at the exhaust point from the thermal combustion chamber using the temperature monitor...

40 CFR 63.364 - Monitoring requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... complying with § 63.363(b) or (d) through the use of an acid-water scrubber, the owner or operator shall... § 63.364(e) or continuously monitor and record the oxidation temperature at the outlet to the catalyst bed or at the exhaust point from the thermal combustion chamber using the temperature monitor...

Sensors, Volume 1, Fundamentals and General Aspects

NASA Astrophysics Data System (ADS)

Grandke, Thomas; Ko, Wen H.

1996-12-01

'Sensors' is the first self-contained series to deal with the whole area of sensors. It describes general aspects, technical and physical fundamentals, construction, function, applications and developments of the various types of sensors. This volume deals with the fundamentals and common principles of sensors and covers the wide areas of principles, technologies, signal processing, and applications. Contents include: Sensor Fundamentals, e.g. Sensor Parameters, Modeling, Design and Packaging; Basic Sensor Technologies, e.g. Thin and Thick Films, Integrated Magnetic Sensors, Optical Fibres and Intergrated Optics, Ceramics and Oxides; Sensor Interfaces, e.g. Signal Processing, Multisensor Signal Processing, Smart Sensors, Interface Systems; Sensor Applications, e.g. Automotive: On-board Sensors, Traffic Surveillance and Control, Home Appliances, Environmental Monitoring, etc. This volume is an indispensable reference work and text book for both specialits and newcomers, researchers and developers.

Study on emission characteristics and reduction strategy of nitrous oxide during wastewater treatment by different processes.

PubMed

Sun, Shichang; Bao, Zhiyuan; Sun, Dezhi

2015-03-01

Given the inexorable increase in global wastewater treatment, increasing amounts of nitrous oxide are expected to be emitted from wastewater treatment plants and released to the atmosphere. It has become imperative to study the emission and control of nitrous oxide in the various wastewater treatment processes currently in use. In the present investigation, the emission characteristics and the factors affecting the release of nitrous oxide were studied via full- and pilot-scale experiments in anoxic-oxic, sequencing batch reactor and oxidation ditch processes. We propose an optimal treatment process and relative strategy for nitrous oxide reduction. Our results show that both the bio-nitrifying and bio-denitrifying treatment units in wastewater treatment plants are the predominant sites for nitrous oxide production in each process, while the aerated treatment units are the critical sources for nitrous oxide emission. Compared with the emission of nitrous oxide from the anoxic-oxic (1.37% of N-influent) and sequencing batch reactor (2.69% of N-influent) processes, much less nitrous oxide (0.25% of N-influent) is emitted from the oxidation ditch process, which we determined as the optimal wastewater treatment process for nitrous oxide reduction, given the current technologies. Nitrous oxide emissions differed with various operating parameters. Controlling the dissolved oxygen concentration at a proper level during nitrification and denitrification and enhancing the utilization rate of organic carbon in the influent for denitrification are the two critical methods for nitrous oxide reduction in the various processes considered.

Simultaneous quantification of epoxy and hydroxy fatty acids as oxidation products of triacylglycerols in edible oils.

PubMed

Xia, Wei; Budge, Suzanne M

2018-02-16

Epoxy and hydroxy fatty acids are important intermediates during lipid oxidation; quantification of both structures may help evaluate the extent of competition among various lipid oxidation pathways. This article describes a method to simultaneously determine saturated- and unsaturated- epoxy and hydroxy fatty acids derived from oxidation of vegetable oils. The experimental procedures employed transesterification with sodium methoxide, separation of epoxy and hydroxy fatty acid methyl esters (FAME) using solid-phase extraction (SPE), and trimethylsilyl (TMS) derivatization of hydroxy groups. GC-MS was used to identify the epoxy and hydroxy FAME in two different SPE fractions, while GC-flame ionization detection (GC-FID) was used to determine their quantities. Epoxy-octadecanoate/octadecenoate and hydroxy-octadecanoate/octadecenoate/octadecadienoate were determined as lipid oxidation products generated from oxidation of sunflower and canola oils. An isomer of methyl 13-hydroxyoctadeca-9,11-dienoate (13-HODE) TMS ether co-eluted with methyl 15-hydroxyoctadeca-9,12-dienoate TMS ether, which was only present in canola oil; thus, GC-MS-selected ion monitoring (GC-MS-SIM) was used to determine the concentration of 13-HODE. The proposed method has been successfully applied to monitor epoxy and hydroxy fatty acids in sunflower oil and canola oil oxidized at 40 °C. Copyright © 2017 Elsevier B.V. All rights reserved.

Oxidation of Cyclohexene to "trans"-1,2-Cyclohexanediol Promoted by "p"-Toluenesulfonic Acid without Organic Solvents

ERIC Educational Resources Information Center

Rosatella, Andreia A.; Afonso, Carlos A. M.; Branco, Lus C.

2011-01-01

This experiment describes a method for cyclohexene oxidation to "trans"-1,2-cyclohexanediol using "p"-toluenesulfonic acid ("p"-TsOH) as promoter and hydrogen peroxide as oxidant in a biphasic system. This method allows conversions up to 97.9% (monitored by [superscript 1]H NMR). "trans"-1,2-Cyclohexanediol was not easily separated from the…

Regulation of Gene Expression during the Onset of Ligninolytic Oxidation by Phanerochaete chrysosporium on Spruce Wood

Treesearch

Premsagar Korripally; Christopher G. Hunt; Carl J. Houtman; Don C. Jones; Peter J. Kitin; Dan Cullen; Kenneth E. Hammel; A. A. Brakhage

2015-01-01

Since uncertainty remains about how white rot fungi oxidize and degrade lignin in wood, it would be useful to monitor changes in fungal gene expression during the onset of ligninolysis on a natural substrate. We grew Phanerochaete chrysosporium on solid spruce wood and included oxidant-sensing beads bearing the fluorometric dye BODIPY 581/591 in...

Electrobioremediation of oil spills.

PubMed

Daghio, Matteo; Aulenta, Federico; Vaiopoulou, Eleni; Franzetti, Andrea; Arends, Jan B A; Sherry, Angela; Suárez-Suárez, Ana; Head, Ian M; Bestetti, Giuseppina; Rabaey, Korneel

2017-05-01

Annually, thousands of oil spills occur across the globe. As a result, petroleum substances and petrochemical compounds are widespread contaminants causing concern due to their toxicity and recalcitrance. Many remediation strategies have been developed using both physicochemical and biological approaches. Biological strategies are most benign, aiming to enhance microbial metabolic activities by supplying limiting inorganic nutrients, electron acceptors or donors, thus stimulating oxidation or reduction of contaminants. A key issue is controlling the supply of electron donors/acceptors. Bioelectrochemical systems (BES) have emerged, in which an electrical current serves as either electron donor or acceptor for oil spill bioremediation. BES are highly controllable and can possibly also serve as biosensors for real time monitoring of the degradation process. Despite being promising, multiple aspects need to be considered to make BES suitable for field applications including system design, electrode materials, operational parameters, mode of action and radius of influence. The microbiological processes, involved in bioelectrochemical contaminant degradation, are currently not fully understood, particularly in relation to electron transfer mechanisms. Especially in sulfate rich environments, the sulfur cycle appears pivotal during hydrocarbon oxidation. This review provides a comprehensive analysis of the research on bioelectrochemical remediation of oil spills and of the key parameters involved in the process. Copyright © 2017 Elsevier Ltd. All rights reserved.

Exchange Bias Optimization by Controlled Oxidation of Cobalt Nanoparticle Films Prepared by Sputter Gas Aggregation

PubMed Central

Antón, Ricardo López; González, Juan A.; Andrés, Juan P.; Normile, Peter S.; Canales-Vázquez, Jesús; Muñiz, Pablo; Riveiro, José M.; De Toro, José A.

2017-01-01

Porous films of cobalt nanoparticles have been obtained by sputter gas aggregation and controllably oxidized by air annealing at 100 °C for progressively longer times (up to more than 1400 h). The magnetic properties of the samples were monitored during the process, with a focus on the exchange bias field. Air annealing proves to be a convenient way to control the Co/CoO ratio in the samples, allowing the optimization of the exchange bias field to a value above 6 kOe at 5 K. The occurrence of the maximum in the exchange bias field is understood in terms of the density of CoO uncompensated spins and their degree of pinning, with the former reducing and the latter increasing upon the growth of a progressively thicker CoO shell. Vertical shifts exhibited in the magnetization loops are found to correlate qualitatively with the peak in the exchange bias field, while an increase in vertical shift observed for longer oxidation times may be explained by a growing fraction of almost completely oxidized particles. The presence of a hummingbird-like form in magnetization loops can be understood in terms of a combination of hard (biased) and soft (unbiased) components; however, the precise origin of the soft phase is as yet unresolved. PMID:28336895

Exchange Bias Optimization by Controlled Oxidation of Cobalt Nanoparticle Films Prepared by Sputter Gas Aggregation.

PubMed

Antón, Ricardo López; González, Juan A; Andrés, Juan P; Normile, Peter S; Canales-Vázquez, Jesús; Muñiz, Pablo; Riveiro, José M; De Toro, José A

2017-03-11

Porous films of cobalt nanoparticles have been obtained by sputter gas aggregation and controllably oxidized by air annealing at 100 °C for progressively longer times (up to more than 1400 h). The magnetic properties of the samples were monitored during the process, with a focus on the exchange bias field. Air annealing proves to be a convenient way to control the Co/CoO ratio in the samples, allowing the optimization of the exchange bias field to a value above 6 kOe at 5 K. The occurrence of the maximum in the exchange bias field is understood in terms of the density of CoO uncompensated spins and their degree of pinning, with the former reducing and the latter increasing upon the growth of a progressively thicker CoO shell. Vertical shifts exhibited in the magnetization loops are found to correlate qualitatively with the peak in the exchange bias field, while an increase in vertical shift observed for longer oxidation times may be explained by a growing fraction of almost completely oxidized particles. The presence of a hummingbird-like form in magnetization loops can be understood in terms of a combination of hard (biased) and soft (unbiased) components; however, the precise origin of the soft phase is as yet unresolved.

Source Tracking of Nitrous Oxide using A Quantum Cascade ...

EPA Pesticide Factsheets

Nitrous oxide is an important greenhouse gas and ozone depleting substance. Nitrification and denitrification are two major biological pathways that are responsible for soil emissions of N2O. However, source tracking of in-situ or laboratory N2O production is still challenging to soil scientists. The objective of this study was to introduce the use of a new technology, quantum cascade laser (QCL) spectroscopy, which allows for significantly improved accuracy and precision to continuously measure real-time N2O for source tracking. This data provides important emission inventory information to air quality and atmospheric chemistry models. The task demonstrated that QCL spectroscopy can measure the flux of nitrous oxide at ambient and well as elevated concentrations in real time. The fractionation of the nitrous oxide produced by microbial processing of nitrate can be measured and characterized as isotopic signatures related to the nitrifying or denitrifying state of the microbial communities. This has important implications for monitoring trace gases in the atmosphere. The data produced by this system will provide clients including the air quality and climate change communities with needed information on the sources and strengths of N2O emissions for modeling and research into mitigation strategies to reduce overall GHG emissions in agricultural systems.

Sensor materials for an intravascular fiber optic nitric oxide sensor

NASA Astrophysics Data System (ADS)

Soller, Babs R.; Parikh, Bhairavi R.; Stahl, Russell F.

1996-04-01

Nitric oxide (NO) is an important regulatory molecule in physiological processes including neurotransmission and the control of blood pressure. It is produced in excess during septic shock, the profound hypotensive state which accompanies severe infections. In-vivo measurement of NO would enhance the understanding of its varied biological roles. Our goal is the development of an intravascular fiber-optic sensor for the continuous measurement of NO. This study evaluated nitric oxide sensitive compounds as potential sensing materials in the presence and absence of oxygen. Using absorption spectroscopy we studied both the Fe II and Fe III forms of three biologically active hemes known to rapidly react with NO: hemoglobin, myoglobin, and cytochrome-c. The Fe II forms of hemoglobin and myoglobin and the Fe III form of cytochrome-c were found to have the highest sensitivity to NO. Cytochrome c (Fe III) is selective for NO even at high oxygen levels, while myoglobin is selective only under normal oxygen levels. NO concentrations as low as 1 (mu) M can be detected with our fiber-optic spectrometer using cytochrome c, and as low as 300 nM using myoglobin. Either of these materials would be adequate to monitor the increase in nitric oxide production during the onset of septic shock.

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

Fang, Kuan-Chung; Chu, Chia-Ho; Hsu, Chen-Pin

In this study, a cost-effective and highly sensitive cholesterol microsensor, which is consisted of cholesterol oxidase (ChOx), horseradish peroxidase (HRP), and polyaniline (PANI), was developed based on the enzyme-induced conductivity change of PANI with fast response. Hydrogen peroxide is produced via the reaction between cholesterol and ChOx, which was immobilized in a dialysis membrane. The produced hydrogen peroxide can oxidize HRP, which can be reduced by oxidizing PANI, thus resulting in decreased conductivity of the polyaniline thin film. The reduced HRP can be oxidized again by hydrogen peroxide and the cycle of the oxidation/reduction continues until all hydrogen peroxide aremore » reacted, leading to the high sensitivity of the sensor due to the signal contributed from all hydrogen peroxide molecules. Cholesterol was detected near the physiological concentrations ranging from 100 mg/dl to 400 mg/dl with the cholesterol microsensors. The results show linear relation between cholesterol concentration and the conductivity change of the PANI. The microsensor showed no response to cholesterol when the PANI was standalone without cholesterol oxidase immobilized, indicating that the enzymatic reaction is required for cholesterol detection. The simple process of the sensor fabrication allows the sensor to be cost-effective and disposable usage. This electronic cholesterol microsensor is promising for point-of-care health monitoring in cholesterol level with low cost and fast response.« less

Redox Active Transition Metal ions Make Melanin Susceptible to Chemical Degradation Induced by Organic Peroxide.

PubMed

Zadlo, Andrzej; Pilat, Anna; Sarna, Michal; Pawlak, Anna; Sarna, Tadeusz

2017-12-01

With aging, retinal pigment epithelium melanosomes, by fusion with the age pigment lipofuscin, form complex granules called melanolipofuscin. Lipofuscin granules may contain oxidized proteins and lipid hydroperoxides, which in melanolipofuscin could chemically modify melanin polymer, while transition metal ions present in melanin can accelerate such oxidative modifications. The aim of this research was to examine the effect of selected transition metal ions on melanin susceptibility to chemical modification induced by the water-soluble tert-butyl hydroperoxide used as an oxidizing agent. Synthetic melanin obtained by DOPA autooxidation and melanosomes isolated from bovine retinal pigment epithelium were analyzed. To monitor tert-butyl hydroperoxide-induced oxidative changes of DMa and BMs, electron paramagnetic resonance spectroscopy, UV-vis absorption spectroscopy, dynamic light scattering, atomic force microscopy and electron paramagnetic resonance oximetry were employed. These measurements revealed that both copper and iron ions accelerated chemical degradation induced by tert-butyl hydroperoxide, while zinc ions had no effect. Strong prooxidant action was detected only in the case of melanosomes and melanin degraded in the presence of iron. It can be postulated that similar chemical processes, if they occur in situ in melanolipofuscin granules of the human retinal pigment epithelium, would modify antioxidant properties of melanin and its reactivity.

Oxidation of Chemically-Vapor-Deposited Silicon Carbide in Carbon Dioxide

NASA Technical Reports Server (NTRS)

Opila, Elizabeth J.; Nguyen, QuynhGiao N.

1998-01-01

Chemically-vapor-deposited silicon carbide (CVD SiC) was oxidized in carbon dioxide (CO2) at temperatures of 1200-1400 C for times between 96 and 500 h at several gas flow rates. Oxidation weight gains were monitored by thermogravimetric analysis (TGA) and were found to be very small and independent of temperature. Possible rate limiting kinetic mechanisms are discussed. Passive oxidation of SiC by CO2 is negligible compared to the rates measured for other oxidants that are also found in combustion environments, oxygen and water vapor.

Application of Iron Oxide as a pH-dependent Indicator for Improving the Nutritional Quality

PubMed Central

2016-01-01

Acid food indicators can be used as pH indicators for evaluating the quality and freshness of fermented products during the full course of distribution. Iron oxide particles are hardly suspended in water, but partially or completely agglomerated. The agglomeration degree of the iron oxide particles depends on the pH. The pH-dependent particle agglomeration or dispersion can be useful for monitoring the acidity of food. The zeta potential of iron oxide showed a decreasing trend as the pH increased from 2 to 8, while the point of zero charge (PZC) was observed around at pH 6.0-7.0. These results suggested that the size of the iron oxide particles was affected by the change in pH levels. As a result, the particle sizes of iron oxide were smaller at lower pH than at neutral pH. In addition, agglomeration of the iron oxide particles increased as the pH increased from 2 to 7. In the time-dependent aggregation test, the average particle size was 730.4 nm and 1,340.3 nm at pH 2 and 7, respectively. These properties of iron oxide particles can be used to develop an ideal acid indicator for food pH and to monitor food quality, besides a colorant or nutrient for nutrition enhancement and sensory promotion in food industry. PMID:27482521

Different effects of water molecules on CO oxidation with different reaction mechanisms.

PubMed

Liu, Shan Ping; Zhao, Ming; Sun, Guo En; Gao, Wang; Jiang, Qing

2018-03-28

The effects of water molecules (promotion/prohibition) on CO oxidation remain debated. Herein, using density functional theory calculations, we demonstrate that water molecules can facilitate the CO + O/O 2 oxidation process, but prohibit the CO + OH oxidation process, which is consistent with the experimental finding that water molecules have two distinct effects on CO oxidation. For the CO + O/O 2 oxidation mechanisms, we find that the reactants were pushed towards each other due to the steric effect of the water molecules, which decreases the reaction barriers and promotes the CO + O/O 2 oxidation process. For the CO + OH oxidation mechanisms, water molecules increase the stability of the COOH* intermeditae by H-bonds and van der Waals forces, which increase the barriers of the COOH* transformation process and the COOH*-tra dissociation process, and prohibit the CO + OH oxidation process. These results clarify the different effects of water molecules on CO oxidation and shed light on catalyst usage in the CO oxidation industry.

Molecular Dynamics Study of Polystyrene-b-poly(ethylene oxide) Asymmetric Diblock Copolymer Systems.

PubMed

Dobies, M; Makrocka-Rydzyk, M; Jenczyk, J; Jarek, M; Spontak, R J; Jurga, S

2017-09-12

Two polystyrene-b-poly(ethylene oxide) (PS-b-PEO) diblock copolymers differing in molecular mass (49 and 78 kDa) but possessing the same PEO cylindrical morphology are examined to elucidate their molecular dynamics. Of particular interest here is the molecular motion of the PEO blocks involved in the rigid amorphous fraction (RAF). An analysis of complementary thermal calorimetry and X-ray scattering data confirms the presence of microphase-separated morphology as well as semicrystalline structure in each copolymer. Molecular motion within the copolymer systems is monitored by dielectric and nuclear magnetic resonance spectroscopies. The results reported herein reveal the existence of two local Arrhenius-type processes attributed to the noncooperative local motion of PEO segments involved in fully amorphous and rigid amorphous PEO microphases. In both systems, two structural relaxations governed by glass-transition phenomena are identified and assigned to cooperative segmental motion in the fully amorphous phase (the α process) and the RAF (the α c process). We measure the temperature dependence of the dynamics associated with all of the processes mentioned above and propose that these local processes are associated with corresponding cooperative segmental motion in both copolymer systems. In marked contrast to the thermal activation of the α process as discerned in both copolymers, the α c process appears to be a sensitive probe of the copolymer nanostructure. That is, the copolymer with shorter PEO blocks exhibits more highly restricted cooperative dynamics of PEO segments in the RAF, which can be explained in terms of the greater constraint imposed by the glassy PS matrix on the PEO blocks comprising smaller cylindrical microdomains.

Silicon Micromachined Sensor for Broadband Vibration Analysis

NASA Technical Reports Server (NTRS)

Gutierrez, Adolfo; Edmans, Daniel; Cormeau, Chris; Seidler, Gernot; Deangelis, Dave; Maby, Edward

1995-01-01

The development of a family of silicon based integrated vibration sensors capable of sensing mechanical resonances over a broad range of frequencies with minimal signal processing requirements is presented. Two basic general embodiments of the concept were designed and fabricated. The first design was structured around an array of cantilever beams and fabricated using the ARPA sponsored multi-user MEMS processing system (MUMPS) process at the Microelectronics Center of North Carolina (MCNC). As part of the design process for this first sensor, a comprehensive finite elements analysis of the resonant modes and stress distribution was performed using PATRAN. The dependence of strain distribution and resonant frequency response as a function of Young's modulus in the Poly-Si structural material was studied. Analytical models were also studied. In-house experimental characterization using optical interferometry techniques were performed under controlled low pressure conditions. A second design, intended to operate in a non-resonant mode and capable of broadband frequency response, was proposed and developed around the concept of a cantilever beam integrated with a feedback control loop to produce a null mode vibration sensor. A proprietary process was used to integrat a metal-oxide semiconductor (MOS) sensing device, with actuators and a cantilever beam, as part of a compatible process. Both devices, once incorporated as part of multifunction data acquisition and telemetry systems will constitute a useful system for NASA launch vibration monitoring operations. Satellite and other space structures can benefit from the sensor for mechanical condition monitoring functions.

Development of mediator-type biosensor to wirelessly monitor whole cholesterol concentration in fish.

PubMed

Takase, Mai; Murata, Masataka; Hibi, Kyoko; Huifeng, Ren; Endo, Hideaki

2014-04-01

We developed a wireless monitoring system to monitor fish condition by tracking the change in whole cholesterol concentration. The whole cholesterol concentration of fish is a source of steroid hormones or indicator of immunity level, which makes its detection important for tracking physiological condition of fish. Wireless monitoring system comprises of mediator-type biosensor and wireless transmission device. Biosensor is implantable to fish body, and transmission device is so light, in that fish is allowed to swim freely during monitoring. Cholesterol esterase and oxidase were fixated on to the detection site of biosensor and used to detect the whole cholesterol concentration. However, cholesterol oxidase incorporates oxidation-reduction reaction of oxygen for detection, which concentration fluctuates easily due to change in environmental condition. Meanwhile, mediator-type biosensor enables monitoring of whole cholesterol concentration by using mediator to substitute that oxidation-reduction reaction of oxygen. Characteristic of fabricated mediator-type biosensor was tested. The sensor output current of mediator-type biosensor remained stable compared to output current of non-mediator-type biosensor under fluctuating oxygen concentration of 0-8 ppm, which implied that this sensor is less affected by change in dissolved oxygen concentration. That biosensor was then implanted into fish for wireless monitoring. As a result, approximately 48 h of real-time monitoring was successful.

Comparison of the effectiveness of soil heating prior or during in situ chemical oxidation (ISCO) of aged PAH-contaminated soils.

PubMed

Ranc, Bérénice; Faure, Pierre; Croze, Véronique; Lorgeoux, Catherine; Simonnot, Marie-Odile

2017-04-01

Thermal treatments prior or during chemical oxidation of aged polycyclic aromatic hydrocarbon (PAH)-contaminated soils have already shown their ability to increase oxidation effectiveness. However, they were never compared on the same soil. Furthermore, oxygenated polycyclic aromatic hydrocarbons (O-PACs), by-products of PAH oxidation which may be more toxic and mobile than the parent PAHs, were very little monitored. In this study, two aged PAH-contaminated soils were heated prior (60 or 90 °C under Ar for 1 week) or during oxidation (60 °C for 1 week) with permanganate and persulfate, and 11 O-PACs were monitored in addition to the 16 US Environmental Protection Agency (US EPA) PAHs. Oxidant doses were based on the stoichiometric oxidant demand of the extractable organic fraction of soils by using organic solvents, which is more representative of the actual contamination than only the 16 US EPA PAHs. Higher temperatures actually resulted in more pollutant degradation. Two treatments were about three times more effective than the others: soil heating to 60 °C during persulfate oxidation and soil preheating to 90 °C followed by permanganate oxidation. The results of this study showed that persulfate effectiveness was largely due to its thermal activation, whereas permanganate was more sensitive to PAH availability than persulfate. The technical feasibility of these two treatments will soon be field-tested in the unsaturated zone of one of the studied aged PAH-contaminated soils.

Nano-Enriched and Autonomous Sensing Framework for Dissolved Oxygen.

PubMed

Shehata, Nader; Azab, Mohammed; Kandas, Ishac; Meehan, Kathleen

2015-08-14

This paper investigates a nano-enhanced wireless sensing framework for dissolved oxygen (DO). The system integrates a nanosensor that employs cerium oxide (ceria) nanoparticles to monitor the concentration of DO in aqueous media via optical fluorescence quenching. We propose a comprehensive sensing framework with the nanosensor equipped with a digital interface where the sensor output is digitized and dispatched wirelessly to a trustworthy data collection and analysis framework for consolidation and information extraction. The proposed system collects and processes the sensor readings to provide clear indications about the current or the anticipated dissolved oxygen levels in the aqueous media.

Effect of interface reaction and diffusion on stress-oxidation coupling at high temperature

NASA Astrophysics Data System (ADS)

Yue, Mengkun; Dong, Xuelin; Fang, Xufei; Feng, Xue

2018-04-01

High-temperature structural materials undergo oxidation during the service, and stress would generate in the oxide film. Understanding the coupling effect between stress and oxidation contributes to the understanding of material degradation and failure during the oxidation process. Here, we propose a model to investigative the coupling effect of stress and oxidation at high temperature by considering the three-stage oxidation process, where both the interface reaction and the diffusion process are present. The governing equations including the oxidation kinetics and stress equilibrium for isothermal oxidation under stress-oxidation coupling effect have been derived. The theory is validated by comparing with the experimental results of SiO2 grown on Si substrate. Results show that the coupling of stress and oxidation influences the growth of the oxide film by affecting all three stages of the oxidation process.

40 CFR 60.1230 - What continuous emission monitoring systems must I install for gaseous pollutants?

Code of Federal Regulations, 2010 CFR

2010-07-01

... systems for oxygen (or carbon dioxide), sulfur dioxide, and carbon monoxide. If you operate a Class I... sulfur dioxide, nitrogen oxides, and oxygen (or carbon dioxide) at the outlet of the air pollution... according to the “Monitoring Requirements” in § 60.13. (c) You must monitor the oxygen (or carbon dioxide...

40 CFR 60.1230 - What continuous emission monitoring systems must I install for gaseous pollutants?

Code of Federal Regulations, 2011 CFR

2011-07-01

... systems for oxygen (or carbon dioxide), sulfur dioxide, and carbon monoxide. If you operate a Class I... sulfur dioxide, nitrogen oxides, and oxygen (or carbon dioxide) at the outlet of the air pollution... according to the “Monitoring Requirements” in § 60.13. (c) You must monitor the oxygen (or carbon dioxide...

40 CFR Part 75 Emissions Monitoring Policy Manual

EPA Pesticide Factsheets

Provides guidance on the requirements of 40 CFR Part 75 through a series of questions and answers that can be used by units to monitor mass sulfur dioxide emissions, mass carbon dioxide emissions, nitrogen oxide rate and heat input.

Characterizing the proteome and oxi-proteome of apple in response to a host (Penicillium expansum) and a non-host (Penicillium digitatum) pathogen.

PubMed

Buron-Moles, Gemma; Wisniewski, Michael; Viñas, Inmaculada; Teixidó, Neus; Usall, Josep; Droby, Samir; Torres, Rosario

2015-01-30

Apples are subjected to both abiotic and biotic stresses during the postharvest period, which lead to large economic losses worldwide. To obtain biochemical insights into apple defense response, we monitored the protein abundance changes (proteome), as well as the protein carbonyls (oxi-proteome) formed by reactive oxygen species (ROS) in 'Golden Smoothee' apple in response to wounding, Penicillium expansum (host) and Penicillium digitatum (non-host) pathogens with select transcriptional studies. To examine the biological relevance of the results, we described quantitative and oxidative protein changes into the gene ontology functional categories, as well as into de KEGG pathways. We identified 26 proteins that differentially changed in abundance in response to wounding, P. expansum or P. digitatum infection. While these changes showed some similarities between the apple responses and abiotic and biotic stresses, Mal d 1.03A case, other proteins as Mal d 1.03E and EF-Tu were specifically induced in response to P. digitatum infection. Using a protein carbonyl detection method based on fluorescent Bodipy, we detected and identified 27 oxidized proteins as sensitive ROS targets. These ROS target proteins were related to metabolism processes, suggesting that this process plays a leading role in apple fruit defense response against abiotic and biotic stresses. ACC oxidase and two glutamine synthetases showed the highest protein oxidation level in response to P. digitatum infection. Documenting changes in the proteome and, specifically in oxi-proteome of apple can provide information that can be used to better understand how impaired protein functions may affect apple defense mechanisms. Possible mechanisms by which these modified proteins are involved in fruit defense response are discussed. Mechanical damage in apple fruits is linked annually to large economic losses due to opportunistic infection by postharvest pathogens, such as P. expansum. Despite the current use of chemical fungicides and the implementation of new alternative strategies, blue mold remains a critical disease of these stored fruits worldwide. Actual trends are focused on acquiring the knowledge of the host-pathogen interactions because it may help on finding new rational and environmentally friendly control alternatives. Despite the economic importance of some postharvest diseases, proteomics has only been applied in a few cases to study fruit-pathogen interactions. On the one hand, this is the first study that monitored changes at the proteome and oxi-proteome level in 'Golden Smoothee' apple fruits in response to P. expansum (compatible) and P. digitatum (non-host) pathogens. On the other hand, the main technological innovation of the reported research is the detection and quantification of oxidized (carbonylated) proteins to assess protein oxidative damage, avoiding the immunoblotting technique. The importance of the biological process investigated lies in the different mechanisms induced in fruit in response to P. expansum and P. digitatum. Results revealed that fruit recognizes and reacts to P. expansum in a similar manner to wounding, while its response to P. digitatum exhibits few differences in the protein profile. Documenting changes in the proteome and, specifically in oxi-proteome of apple can provide information that can be used to better understand how impaired protein functions may affect apple defense mechanisms. It also provides new biomarkers for oxidative damage mainly caused by the oxidative response occurring in fruit tissue in response to a host and a non-host pathogen. Copyright © 2014 Elsevier B.V. All rights reserved.

KSC-2009-2584

NASA Image and Video Library

2009-03-22

CAPE CANAVERAL, Fla. – In the Astrotech payload processing facility in Titusville, Fla., technicians monitor the alignment of the GOES-O satellite onto a special stand for loading of its oxidizer and hydrazine propellants. The latest Geostationary Operational Environmental Satellite, GOES-O was developed by NASA for the National Oceanic and Atmospheric Administration, or NOAA. The GOES satellites continuously provide observations of 60 percent of the Earth including the continental United States, providing weather monitoring and forecast operations as well as a continuous and reliable stream of environmental information and severe weather warnings. Once in orbit, GOES-O will be designated GOES-14, and NASA will provide on-orbit checkout and then transfer operational responsibility to NOAA. The GOES-O satellite is targeted to launch from Cape Canaveral Air Force Station's Launch Complex 37 no earlier than May 12 onboard a United Launch Alliance Delta IV expendable launch vehicle. Photo credit: NASA/Troy Cryder

Theoretical analysis and simulation study of low-power CMOS electrochemical impedance spectroscopy biosensor in 55 nm deeply depleted channel technology for cell-state monitoring

NASA Astrophysics Data System (ADS)

Itakura, Keisuke; Kayano, Keisuke; Nakazato, Kazuo; Niitsu, Kiichi

2018-01-01

We present an impedance-detection complementary metal oxide semiconductor (CMOS) biosensor circuit for cell-state observation. The proposed biosensor can measure the expected impedance values encountered by a cell-state observation measurement system within a 0.1-200 MHz frequency range. The proposed device is capable of monitoring the intracellular conditions necessary for real-time cell-state observation, and can be fabricated using a 55 nm deeply depleted channel CMOS process. Operation of the biosensor circuit with 0.9 and 1.7 V supply voltages is verified via a simulated program with integrated circuit emphasis (SPICE) simulation. The power consumption is 300 µW. Further, the standby power consumption is 290 µW, indicating that this biosensor is a low-power instrument suitable for use in Internet of Things (IoT) devices.

KSC-2009-2579

NASA Image and Video Library

2009-03-22

CAPE CANAVERAL, Fla. – In the Astrotech payload processing facility in Titusville, Fla., technicians monitor the lift of the GOES-O satellite toward a special stand for loading of its oxidizer and hydrazine propellants. The latest Geostationary Operational Environmental Satellite, GOES-O was developed by NASA for the National Oceanic and Atmospheric Administration, or NOAA. The GOES satellites continuously provide observations of 60 percent of the Earth including the continental United States, providing weather monitoring and forecast operations as well as a continuous and reliable stream of environmental information and severe weather warnings. Once in orbit, GOES-O will be designated GOES-14, and NASA will provide on-orbit checkout and then transfer operational responsibility to NOAA. The GOES-O satellite is targeted to launch from Cape Canaveral Air Force Station's Launch Complex 37 no earlier than May 12 onboard a United Launch Alliance Delta IV expendable launch vehicle. Photo credit: NASA/Troy Cryder

Insights into characteristics, sources, and evolution of submicron aerosols during harvest seasons in the Yangtze River delta region, China

NASA Astrophysics Data System (ADS)

Zhang, Y. J.; Tang, L. L.; Wang, Z.; Yu, H. X.; Sun, Y. L.; Liu, D.; Qin, W.; Canonaco, F.; Prévôt, A. S. H.; Zhang, H. L.; Zhou, H. C.

2015-02-01

Atmospheric submicron particulate matter (PM1) is one of the most significant pollution components in China. Despite its current popularity in the studies of aerosol chemistry, the characteristics, sources and evolution of atmospheric PM1 species are still poorly understood in China, particularly for the two harvest seasons, namely, the summer wheat harvest and autumn rice harvest. An Aerodyne Aerosol Chemical Speciation Monitor (ACSM) was deployed for online monitoring of PM1 components during summer and autumn harvest seasons in urban Nanjing, in the Yangtze River delta (YRD) region of China. PM1 components were shown to be dominated by organic aerosol (OA, 39 and 41%) and nitrate (23 and 20%) during the harvest seasons (the summer and autumn harvest). Positive matrix factorization (PMF) analysis of the ACSM OA mass spectra resolved four OA factors: hydrocarbon-like mixed with cooking-related OA (HOA + COA), fresh biomass-burning OA (BBOA), oxidized biomass-burning-influenced OA (OOA-BB), and highly oxidized OA (OOA); in particular the oxidized BBOA contributes ~80% of the total BBOA loadings. Both fresh and oxidized BBOA exhibited apparent diurnal cycles with peak concentration at night, when the high ambient relative humidity and low temperature facilitated the partitioning of semi-volatile organic species into the particle phase. The fresh BBOA concentrations for the harvests are estimated as BBOA = 15.1 × (m/z 60-0.26% × OA), where m/z (mass-to-charge ratio) 60 is a marker for levoglucosan-like species. The (BBOA + OOA-BB)/ΔCO, (ΔCO is the CO minus background CO), decreases as a function of f44 (fraction of m/z 44 in OA signal), which might indicate that BBOA was oxidized to less volatile OOA, e.g., more aged and low volatility OOA (LV-OOA) during the aging process. Analysis of air mass back trajectories indicates that the high BB pollutant concentrations are linked to the air masses from the western (summer harvest) and southern (autumn harvest) areas.

Applying Molecular Tools for Monitoring Inhibition of Nitrification by Heavy Metals

EPA Science Inventory

The biological removal of ammonia in conventional wastewater treatment plants (WWTPs) is performed by promoting nitrification and denitrification as sequential steps. The first step in nitrification, the oxidation of ammonia to nitrite by ammonia oxidizing bacteria (AOB), is sens...

40 CFR 63.364 - Monitoring requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

...) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE CATEGORIES Ethylene Oxide Emissions.... (2) Each owner or operator of an ethylene oxide sterilization facility subject to these emissions...: (1) Sample the scrubber liquor and analyze and record once per week the ethylene glycol concentration...

Evaluation of low-cost electro-chemical sensors for environmental monitoring of ozone, nitrogen dioxide, and carbon monoxide.

PubMed

Afshar-Mohajer, Nima; Zuidema, Christopher; Sousan, Sinan; Hallett, Laura; Tatum, Marcus; Rule, Ana M; Thomas, Geb; Peters, Thomas M; Koehler, Kirsten

2018-02-01

Development of an air quality monitoring network with high spatio-temporal resolution requires installation of a large number of air pollutant monitors. However, state-of-the-art monitors are costly and may not be compatible with wireless data logging systems. In this study, low-cost electro-chemical sensors manufactured by Alphasense Ltd. for detection of CO and oxidative gases (predominantly O 3 and NO 2 ) were evaluated. The voltages from three oxidative gas sensors and three CO sensors were recorded every 2.5 sec when exposed to controlled gas concentrations in a 0.125-m 3 acrylic glass chamber. Electro-chemical sensors for detection of oxidative gases demonstrated sensitivity to both NO 2 and O 3 with similar voltages recorded when exposed to equivalent environmental concentrations of NO 2 or O 3 gases, when evaluated separately. There was a strong linear relationship between the recorded voltages and target concentrations of oxidative gases (R 2 > 0.98) over a wide range of concentrations. Although a strong linear relationship was also observed for CO concentrations below 12 ppm, a saturation effect was observed wherein the voltage only changes minimally for higher CO concentrations (12-50 ppm). The nonlinear behavior of the CO sensors implied their unsuitability for environments where high CO concentrations are expected. Using a manufacturer-supplied shroud, sensors were tested at 2 different flow rates (0.25 and 0.5 Lpm) to mimic field calibration of the sensors with zero air and a span gas concentration (2 ppm NO2 or 15 ppm CO). As with all electrochemical sensors, the tested devices were subject to drift with a bias up to 20% after 9 months of continuous operation. Alphasense CO sensors were found to be a proper choice for occupational and environmental CO monitoring with maximum concentration of 12 ppm, especially due to the field-ready calibration capability. Alphasense oxidative gas sensors are usable only if it is valuable to know the sum of the NO 2 and O 3 concentrations.

Photochemical Assessment Monitoring Stations (PAMS)

EPA Pesticide Factsheets

Photochemical Assessment Monitoring Stations (PAMS). This file provides information on the numbers and distribution (latitude/longitude) of air monitoring sites which measure ozone precursors (approximately 60 volatile hydrocarbons and carbonyl), as required by the 1990 Clean Air Act Amendments, in areas with persistently high ozone levels (mostly large metropolitan areas). In these areas, the States have established ambient air monitoring sites which collect and report detailed data for volatile organic compounds, nitrogen oxides, ozone and meteorological parameters. This file displays 199 monitoring sites reporting measurements for 2010. A wide range of related monitoring site attributes is also provided.