WorldWideScience

Sample records for mercaptans

  1. SPECTROSCOPIC CHARACTERIZATION AND DETECTION OF ETHYL MERCAPTAN IN ORION

    International Nuclear Information System (INIS)

    Kolesniková, L.; Alonso, J. L.; Daly, A. M.; Tercero, B.; Cernicharo, J.; Gordon, B. P.; Shipman, S. T.

    2014-01-01

    New laboratory data of ethyl mercaptan, CH 3 CH 2 SH, in the millimeter- and submillimeter-wave domains (up to 880 GHz) provided very precise values of the spectroscopic constants that allowed the detection of gauche-CH 3 CH 2 SH toward Orion KL. This identification is supported by 77 unblended or slightly blended lines plus no missing transitions in the range 80-280 GHz. A detection of methyl mercaptan, CH 3 SH, in the spectral survey of Orion KL is reported as well. Our column density results indicate that methyl mercaptan is ≅ 5 times more abundant than ethyl mercaptan in the hot core of Orion KL

  2. Triazine chemistry: removing H2S and mercaptans

    Energy Technology Data Exchange (ETDEWEB)

    Owens, Thomas R.; Lesage, Kevin L.; Clark, Peter D.; Primak, Alex [University of Calgary (Canada)

    2011-07-01

    Chemical scavengers like triazines cause sulfur to be deposited with by-products and not in its pure form. This paper presents techniques to remove H2S and mercaptans. One process for H2S scavenging is injection of formaldehyde into the pipelines. But this causes solids to be formed as by-products. Triazine chemistry and synthesis and reaction mechanisms for H2S and its by-products that are formed are shown. Some of the mitigation strategies include maintaining optimal methanol concentration and running the chemical at lower scavenging efficiencies. There are no documented issues regarding the reaction of triazines with mercaptans. The experimental setup and process are explained and the results show that scavenging efficiency for mercaptans is inversely related to its molecular weight. Improved scavenging systems and various methods for mercaptan scavenging are given. From the study it can be concluded that triazine-based scavengers efficiently remove low levels of H2S from gas streams but not mercaptans.

  3. Vapor-Liquid Equilibrium Measurements and Modeling of the Propyl Mercaptan plus Methane plus Water System

    DEFF Research Database (Denmark)

    Awan, Javeed; Thomsen, Kaj; Coquelet, Christophe

    2010-01-01

    In this work, vapor−liquid equilibrium (VLE) measurements of propyl mercaptan (PM) in pure water were performed at three different temperatures, (303, 323, and 365) K, with a pressure variation from (1 to 8) MPa. The total system pressure was maintained by CH4. The inlet mole fraction of propyl...... mercaptan in all experiments was the same, around 4.5·10−4 in the liquid phase. The objective was to provide experimental VLE data points of the propyl mercaptan + methane + water system for modeling since there is a lack of available data. These data will allow the industrial modeling of sulfur emission...

  4. Optimization of Hydrogen Peroxide Detection for a Methyl Mercaptan Biosensor

    Directory of Open Access Journals (Sweden)

    Shi-Gang Sun

    2013-04-01

    Full Text Available Several kinds of modified carbon screen printed electrodes (CSPEs for amperometric detection of hydrogen peroxide (H2O2 are presented in order to propose a methyl mercaptan (MM biosensor. Unmodified, carbon nanotubes (CNTs, cobalt phthalocyanine (CoPC, Prussian blue (PB, and Os-wired HRP modified CSPE sensors were fabricated and tested to detect H2O2, applying a potential of +0.6 V, +0.6 V, +0.4 V, −0.2 V and −0.1 V (versus Ag/AgCl, respectively. The limits of detection of these electrodes for H2O2 were 3.1 μM, 1.3 μM, 71 nM, 1.3 μM, 13.7 nM, respectively. The results demonstrated that the Os-wired HRP modified CSPEs gives the lowest limit of detection (LOD for H2O2 at a working potential as low as −0.1 V. Os-wired HRP is the optimum choice for establishment of a MM biosensor and gives a detection limit of 0.5 μM.

  5. Influence of methyl mercaptan on the repair bond strength of composites fabricated using self-etch adhesives.

    Science.gov (United States)

    Yokokawa, Miho; Rikuta, Akitomo; Tsujimoto, Akimasa; Tsuchiya, Kenji; Shibasaki, Syo; Matsuyoshi, Saki; Miyazaki, Masashi

    2015-02-01

    The influence of methyl mercaptan on the repair bond strength of composites fabricated using self-etch adhesives was investigated. The surface free-energies were determined by measuring the contact angles of test liquids placed on composites that had been immersed in different concentrations of methyl mercaptan (0.01, 0.1, and 1.0 M). To determine the repair bond strength, self-etch adhesives were applied to the aged composite, and then newly added composites were condensed. Ten samples of each specimen were subjected to shear testing at a crosshead speed of 1.0 mm min(-1). Samples were analyzed using two-way ANOVA followed by Tukey's honestly significant difference (HSD) test. Although the dispersion force of the composites remained relatively constant, their polar force increased slightly as the concentration of methyl mercaptan increased. The hydrogen-bonding forces were significantly higher after immersion in 1.0 M methyl mercaptan, leading to higher surface-free energies. However, the repair bond strengths for the repair restorations prepared from composites immersed in 1.0 M methyl mercaptan were significantly lower than for those immersed in 0.01 and 0.10 M methyl mercaptan. Considering the results of this study, it can be concluded that the repair bond strengths of both the aged and newly added composites were affected by immersion in methyl mercaptan solutions. © 2014 Eur J Oral Sci.

  6. Healing of fatigue crack in epoxy materials with epoxy/mercaptan system via manual infiltration

    Directory of Open Access Journals (Sweden)

    2010-10-01

    Full Text Available The present work verified the capability of epoxy/mercaptan/tertiary amine system for retarding and/or arresting fatigue cracks in epoxy materials subjected to cyclic loading at room temperature. By using static and dynamic manual infiltration methods, the effects of hydrodynamic pressure crack tip shielding, polymeric wedge and adhesive bonding of the healing agent were revealed. Depending on the applied stress intensity range and the competition between polymerization kinetics of the healing agent and crack growth rate, the above mechanisms exerted different influences on crack retardation under different circumstances. On the whole, the epoxy/mercaptan/tertiary amine system proved to be very effective in obstructing fatigue crack propagation. It formed a promising base for developing self-healing epoxy materials that enable in-situ autonomic rehabilitation of fatigue crack.

  7. Effect of Citrus aurantifolia swingle essential oils on methyl mercaptan production of Porphyromonas gingivalis

    Directory of Open Access Journals (Sweden)

    Anindya Prima Yusinta

    2013-03-01

    Full Text Available Background: Halitosis is a term used to describe an unpleasant odors emanating timely from oral cavity. The unpleasant smell of breath most common caused from volatile sulphure compound (VSC. Methyl mercaptan is the major component of VSC. P. gingivalis produced large amount of methyl mercaptan. The essential oils of Citrus aurantifolia swingle contain antibacterial component. Purpose: The purpose of this study was to determine the effect of essential oil of Citrus aurantifolia swingle on the production of methyl mercaptan compounds in P. gingivalis. Methods: Bacterial suspension of P. gingivalis in TSB medium with 108 CFU/ml concentration cultured in a microplate and added by the essential oils of Citrus aurantifolia swingle with 1%, 2%, 3% and 4% concentration. Distilled water was used as negative control and 0.2% Chlorhexidine mouthwash was used as a positive control. Microplate was incubated anaerobically for 48 hours. After the periode of incubation, 0.6% methionine as the exogenous substrate and 0.06% DTNB as a reagen for determining methyl mercaptan concentration were added to each wells. The microplate was futher incubated for 12 hours. Concentration of methyl mercaptan produced by the P. gingivalis was measured spectrophotometrically using microplate reader at 415 nm. Results: One-way ANOVA showed that the essential oil of Citrus aurantifolia swingle take effect on the concentration of methyl mercaptan produced by P. gingivalis. LSD test results indicated that there was a significant difference of methyl mercaptan concentration between treatment groups of the essential oils of Citrus aurantifolia swingle and distilled water that used as negative control. Conclusion: The essential oil of Citrus aurantifolia swingle has decreased the production of methyl mercaptan produced by P. gingivalis.Latar belakang: Halitosis adalah istilah yang digunakan untuk menggambarkan bau tidak sedap yang berasal dari rongga mulut. Penyebab utama halitosis

  8. Accurate spectroscopic characterization of ethyl mercaptan and dimethyl sulfide isotopologues: a route toward their astrophysical detection

    Energy Technology Data Exchange (ETDEWEB)

    Puzzarini, C. [Dipartimento di Chimica, " Giacomo Ciamician," Università diBologna, Via F. Selmi 2, I-40126 Bologna (Italy); Senent, M. L. [Departamento de Química y Física Teóricas, Institsuto de Estructura de la Materia, IEM-C.S.I.C., Serrano 121, Madrid E-28006 (Spain); Domínguez-Gómez, R. [Doctora Vinculada IEM-CSIC, Departamento de Ingeniería Civil, Cátedra de Química, E.U.I.T. Obras Públicas, Universidad Politécnica de Madrid (Spain); Carvajal, M. [Departamento de Física Aplicada, Facultad de Ciencias Experimentales, Unidad Asociada IEM-CSIC-U.Huelva, Universidad de Huelva, E-21071 Huelva (Spain); Hochlaf, M. [Université Paris-Est, Laboratoire de Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, 5 boulevard Descartes, F-77454 Marne-la-Vallée (France); Al-Mogren, M. Mogren, E-mail: cristina.puzzarini@unibo.it, E-mail: senent@iem.cfmac.csic.es, E-mail: rosa.dominguez@upm.es, E-mail: miguel.carvajal@dfa.uhu.es, E-mail: majdi.hochlaf@u-pem.fr, E-mail: mmogren@ksu.edu.sa [Chemistry Department, Faculty of Science, King Saud University, PO Box 2455, Riyadh 11451 (Saudi Arabia)

    2014-11-20

    Using state-of-the-art computational methodologies, we predict a set of reliable rotational and torsional parameters for ethyl mercaptan and dimethyl sulfide monosubstituted isotopologues. This includes rotational, quartic, and sextic centrifugal-distortion constants, torsional levels, and torsional splittings. The accuracy of the present data was assessed from a comparison to the available experimental data. Generally, our computed parameters should help in the characterization and the identification of these organo-sulfur molecules in laboratory settings and in the interstellar medium.

  9. Detection of Atmospheric Methyl Mercaptan Using Wavelength Modulation Spectroscopy with Multicomponent Spectral Fitting

    Directory of Open Access Journals (Sweden)

    Zhenhui Du

    2017-02-01

    Full Text Available Detection of methyl mercaptan (CH3SH is essential for environmental atmosphere assessment and exhaled-breath analysis. This paper presents a sensitive CH3SH sensor based on wavelength modulation spectroscopy (WMS with a mid-infrared distributed feedback interband cascade laser (DFB-ICL. Multicomponent spectral fitting was used not only to enhance the sensitivity of the sensor but also to determine the concentration of interferents (atmospheric water and methane. The results showed that the uncertainties in the measurement of CH3SH, H2O, and CH4 were less than 1.2%, 1.7% and 2.0%, respectively, with an integration time of 10 s. The CH3SH detection limit was as low as 7.1 ppb with an integration time of 295 s. Overall, the reported sensor, boasting the merits of high sensitivity, can be used for atmospheric methyl mercaptan detection, as well as multiple components detection of methyl mercaptan, water, and methane, simultaneously.

  10. [Optical Analysis of the Interaction of Mercaptan Derivatives of Nanogold Particles with Carcinoembryonic Antigen].

    Science.gov (United States)

    Zeng, Hong-juan; Zhao, Ran-lin; Wang, De-shun; Li, Cai-xia; Liu, Yi-yao

    2016-02-01

    be prepared. In this paper, novel mercaptan derivative of nanogold particles are prepared and studied using transmission electron microscopy (TEM), ultra-violet-visible absorption spectra (UV-Vis), fluorescence emission (FE) spectrum and infrared spectrum (IR) methods. The UV-Vis and FE results show the presence of new ligands mercaptan, more electrons from the orbit of ligand which can excite to the central ion related orbits and increase fluorescence of gold. Fluorescence sensitization effect was observed when mercaptan derivatives of nanogold interacted with carcinoembryonic antigen (CEA) and no fluorescence sensitization effect was found when nanogold interacted with carcinoembryonic antigen (CEA). The study of CEA hyperchromic mechanism of mercaptan derivatives nanogold and the CEA by the method of infrared spectrum, shows that the randomized OH bonds in the Au-protein interaction, showed more on the outside of the plane of bending vibration after the interaction with the mercaptan derivative nanogold, making the energy transfer from mercaptan derivatives nanogold to protein easy; leading to its fluorescence sensitization effect.

  11. H2S and mercaptans in the air in the Molve gas field

    International Nuclear Information System (INIS)

    Vadjic, V.; Tomic, M.

    1995-01-01

    During the processing and refining of natural gas the working areas and ambient air can be polluted by emission of specific pollutants. The natural gas from gas and gas-condensate fields Molve, Stari Gradac and Kalinovac near Bjelovar in northern Croatia contains high levels of hydrogen sulphide and mercaptans. At the central gas station located in the gas field Molve the sour gas from all fields is collected and cleaned by absorption of sulphur compounds in K 2 CO 3 solution before emission to the atmosphere

  12. Self-Assembled Mercaptan on Mesoporous Silica (SAMMS) technology of mercury removal and stabilization

    International Nuclear Information System (INIS)

    Feng, Xiangdong; Liu, Jun; Fryxell, G.E.

    1997-09-01

    This paper explains the technology developed to produce Self-Assembled Mercaptan on Mesoporous Silica (SAMMS) for mercury removal from aqueous wastewater and from organic wastes. The characteristics of SAMMS materials, including physical characteristics and mercury loading, and its application for mercury removal and stabilization are discussed. Binding kinetics and binding speciations are reported. Preliminary cost estimates are provided for producing SAMMS materials and for mercury removal from wastewater. The characteristics of SAMMS in mercury separation were studied at PNNL using simulated aqueous tank wastes and actual tritiated pump oil wastes from Savannah River Site; preliminary results are outlined. 47 refs., 16 figs., 16 tabs

  13. Self-Assembled Mercaptan on Mesoporous Silica (SAMMS) technology of mercury removal and stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Xiangdong; Liu, Jun; Fryxell, G.E. [and others

    1997-09-01

    This paper explains the technology developed to produce Self-Assembled Mercaptan on Mesoporous Silica (SAMMS) for mercury removal from aqueous wastewater and from organic wastes. The characteristics of SAMMS materials, including physical characteristics and mercury loading, and its application for mercury removal and stabilization are discussed. Binding kinetics and binding speciations are reported. Preliminary cost estimates are provided for producing SAMMS materials and for mercury removal from wastewater. The characteristics of SAMMS in mercury separation were studied at PNNL using simulated aqueous tank wastes and actual tritiated pump oil wastes from Savannah River Site; preliminary results are outlined. 47 refs., 16 figs., 16 tabs.

  14. Degradation of ethyl mercaptan and its major intermediate diethyl disulfide by Pseudomonas sp. strain WL2.

    Science.gov (United States)

    Wang, Xiangqian; Wu, Chao; Liu, Nan; Li, Sujing; Li, Wei; Chen, Jianmeng; Chen, Dongzhi

    2015-04-01

    A Pseudomonas sp. strain WL2 that is able to efficiently metabolize ethyl mercaptan (EM) into diethyl disulfide (DEDS) through enzymatic oxidation was isolated from the activated sludge of a pharmaceutical wastewater plant. One hundred percent removal of 113.5 mg L(-1) EM and 110.3 mg L(-1) DEDS were obtained within 14 and 32 h, respectively. A putative EM degradation pathway that involved the catabolism via DEDS was proposed, which indicated DEDS were further mineralized into carbon dioxide (CO2), bacterial cells, and sulfate (SO4 (2-)) through the transformation of element sulfur and ethyl aldehyde. Degradation kinetics for EM and DEDS with different initial concentrations by strain WL2 were evaluated using Haldane-Andrews model with maximum specific degradation rates of 3.13 and 1.33 g g(-1) h(-1), respectively, and maximum degradation rate constants of 0.522 and 0.175 h(-1) using pseudo-first-order kinetic model were obtained. Results obtained that aerobic degradation of EM by strain WL2 was more efficient than those from previous studies. Substrate range studies of strain WL2 demonstrated its ability to degrade several mercaptans, disulfides, aldehydes, and methanol. All the results obtained highlight the potential of strain WL2 for the use in the biodegradation of volatile organic sulfur compounds (VOSCs).

  15. Lap shear strength and healing capability of self-healing adhesive containing epoxy/mercaptan microcapsules

    International Nuclear Information System (INIS)

    Ghazali, Habibah; Ye, Lin; Zhang, Ming-Qiu

    2016-01-01

    The aim of this work is to develop a self-healing polymeric adhesive formulation with epoxy/mercaptan microcapsules. Epoxy/mercaptan microcapsules were dispersed into a commercialize two-part epoxy adhesive for developing self-healing epoxy adhesive. The influence of different content of microcapsules on the shear strength and healing capability of epoxy adhesive were investigated using single-lap-joints with average thickness of adhesive layer of about 180 µm. This self-healing adhesive was used in bonding of 5000 series aluminum alloys adherents after mechanical and alkaline cleaning surface treatment. The adhesion strength was measured and presented as function of microcapsules loading. The results indicated that the virgin lap shear strength was increased by about 26% with addition of 3 wt% of self-healing microcapsules. 12% to 28% recovery of the shear strength is achieved after self-healing depending on the microcapsules content. Scanning electron microscopy was used to study fracture surface of the joints. The self-healing adhesives exhibit recovery of both cohesion and adhesion properties with room temperature healing.

  16. Advances in Global Modelling of Methyl Mercaptan CH_{3}^{32}SH Torsion-Rotation Spectrum

    Science.gov (United States)

    Ilyushin, V.; Armieieva, Iuliia; Zakharenko, Olena; Müller, Holger S. P.; Lewen, Frank; Schlemmer, Stephan; Xu, Li-Hong; Lees, Ronald M.

    2017-06-01

    A progress in the analysis of the methyl mercaptan CH_{3}SH spectrum in its ground, first and second excited torsional states is reported. The available in the literature data were reanalyzed using RAM36 code with the main improvement achieved for the root mean square deviation of the microwave data. The updated Hamiltonian model was applied to the further assignments of the methyl mercaptan spectrum using the records obtained in the THz region in the previous study^{b} . Also a new measurement campaign in subTHz frequency range is planned for the nearest future using a set of spectrometers available in Köln. In the talk the details of this new study will be discussed. This work was done under support of the Volkswagen foundation. The assistance of Science and Technology Center in Ukraine is acknowledged (STCU partner project P686). L.-H. Xu, R. M. Lees, G. T. Crabbe, J. A. Myshrall, H. S. P. Müller, C. P. Endres, O. Baum, F. Lewen, S. Schlemmer, K. M. Menten, and B. E. Billinghurst J. Chem. Phys. 137, 104313 (2012). V. Ilyushin, Z. Kisiel, L. Pszczólkowski, H. Mäder, J. T. Hougen J. Mol. Spectrosc. Vol. 259, pp. 26-38 (2010).

  17. Lap shear strength and healing capability of self-healing adhesive containing epoxy/mercaptan microcapsules

    Energy Technology Data Exchange (ETDEWEB)

    Ghazali, Habibah; Ye, Lin [Centre for Advanced Materials Technology (CAMT), School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006 (Australia); Zhang, Ming-Qiu [Key Laboratory of Polymeric Composite and Functional Materials of Ministry of Education, Zhongshan University, Guangzhou 510275 (China)

    2016-03-09

    The aim of this work is to develop a self-healing polymeric adhesive formulation with epoxy/mercaptan microcapsules. Epoxy/mercaptan microcapsules were dispersed into a commercialize two-part epoxy adhesive for developing self-healing epoxy adhesive. The influence of different content of microcapsules on the shear strength and healing capability of epoxy adhesive were investigated using single-lap-joints with average thickness of adhesive layer of about 180 µm. This self-healing adhesive was used in bonding of 5000 series aluminum alloys adherents after mechanical and alkaline cleaning surface treatment. The adhesion strength was measured and presented as function of microcapsules loading. The results indicated that the virgin lap shear strength was increased by about 26% with addition of 3 wt% of self-healing microcapsules. 12% to 28% recovery of the shear strength is achieved after self-healing depending on the microcapsules content. Scanning electron microscopy was used to study fracture surface of the joints. The self-healing adhesives exhibit recovery of both cohesion and adhesion properties with room temperature healing.

  18. Development of a real-time absorption method for detecting the mercaptan odorizing mixture of natural gas

    NARCIS (Netherlands)

    Kireev, SV; Petrov, NG; Podolyako, EM; Shnyrev, SL

    The absorption of mercaptan mixtures used for odorizing natural gas and mixtures of natural gas is experimentally studied in the spectral range 2.5-20 mu m. An absorption method for the real-time detection of the odorant concentration is proposed. The method is based on intensity measurements of the

  19. Self-healing of fatigue crack in epoxy materials with epoxy/mercaptan system

    Directory of Open Access Journals (Sweden)

    2011-01-01

    Full Text Available Successful retardation or arrest of fatigue crack is observed in self-healing epoxy composite containing dual encapsulated healant, i.e. two types of microcapsules that respectively include epoxy prepolymer and mercaptan/tertiary amine hardener. Fast curing of the released healing agent from the broken capsules leads to rapid development of its bonding strength and fracture toughness at room temperature. It is found that the effects of microcapsules induced-toughening, hydrodynamic pressure crack tip shielding, polymeric wedge and adhesive bonding of the healing agent are responsible for the extension of fatigue life. Depending on the applied stress intensity range, ΔKI, and the competition between polymerization kinetics of the healing agent and crack growth rate, the above mechanisms exert different influences on crack retardation. The results might serve as a reference for further improving the performance of the healant system under fatigue circumstances.

  20. New Look at odorization levels for propane gas. [Ethyl mercaptan; thiophane; equilibrium K values

    Energy Technology Data Exchange (ETDEWEB)

    Whisman, M.L.; Goetzinger, J.W.; Cotton, F.O.; Brinkman, D.W.; Thompson, C.J.

    1977-09-01

    Nearly 4,000 persons participated in a study to evaluate three odorant systems in four test modes and at 24 different test sites. Participants included trained panels, untrained ERDA employees, and several thousand untrained volunteer evaluators. The classical testing technique and three modified test modes were used to represent a spectrum of conditions that would define the effect of environmental familiarity and mental distractions upon olfactory responses to LP-gas. Significant efforts were directed toward determination of odorant levels that not only can be detected but also will be detected. The study showed that in addition to defects of the nasal anatomy, psychological factors also affect olfactory responses, and that unfamiliarity with a given environment as well as anxieties or mental distractions can produce reduced awareness to odorants intended to warn individuals of the presence of LP-gas. A second part of the study involved a laboratory determination of equilibrium K-values for both ethyl mercaptan and thiophane at three temperatures. Novel sample handling and gas chromatographic techniques provided reproducible results which were in close agreement with theoretical predictions. (28 tables, 29 tables)

  1. XAS study of mercury(II) ions trapped in mercaptan-functionalized mesostructured silicate with a wormhole framework structure.

    Science.gov (United States)

    Chen, Chia-Chen; McKimmy, Emily J; Pinnavaia, Thomas J; Hayes, Kim F

    2004-09-15

    Directly assembled wormhole mesostructures with high level functionalized mercaptan (MP-HMS) have been shown to be effective mercury(II) (Hg2+) trapping agents. Sorption of Hg2+ onto MP-HMS was investigated using X-ray absorption spectroscopy (XAS) to identify the structural coordination of the adsorbed Hg. Samples with different fractions of mercaptan functionalized groups (i.e., x = 0.1 and 0.5) with various Hg/S molar ratios ranging from 0.05 to 1.4 were investigated. XAS analysis indicates that adsorbed Hg first coordination shell is best fitted with an Hg-O path and an Hg-S path. The Hg-S atomic distance (R(Hg-S)) remained relatively constant while the Hg-S coordination numbers (CN) decreased as Hg/S loading increased. For the Hg-O path, both the CN and the R(Hg-O) increased with increasing Hg loading. XAS results suggest that at low Hg loadings, adsorbed Hg2+ forms mostly monodentate sulfur complexes (-S-Hg-OH) with the sulfur functional groups on the MP-HMS surfaces. At high Hg loadings, the Hg coordination environment is consistent with the formation of a double-layer structure of Hg attached to sulfur binding sites (-S-Hg-O-Hg-OH).

  2. Effects of mercaptans and disulfides on photochemical and high energy radiation induced reactions. Progress report, November 1, 1974--October 31, 1975

    International Nuclear Information System (INIS)

    Cohen, S.G.

    1975-10-01

    A chain reaction may be formulated at alkaline pH in terms of e - /sub aq/ acting as a source of - OH as a reactant and H. regenerating e - /sub aq/. This may account for radiolytic conversion of CO to formate with high G. 60 Co γ-radiolysis of alkaline aqueous acetonitrile and acetamide gave no evidence of a chain; extensive hydrolysis of methyl acetate is now attributed to non-radiolytic, normal hydrolysis. Aromatic mercaptans are found to retard photoreduction of a benzophenone by aliphatic amines, largely by hydrogen atom-transfer repair reactions. Aliphatic mercaptans accelerate photoreduction, apparently by affecting the reduction to quenching ratio in the intermediate charge-transfer complex. In photoreduction of a benzophenone by 2,3-butylene glycol at pH 3, the glycol is converted, not to 3-hydroxy-2-butanone, but to 2-butanone, and about 4 molecules of this are formed per molecule of ketone reduced. A short chain appears to be established. Mercaptan appears to accelerate the reduction of the ketone and retard the formation of 2-butanone

  3. Hybrid Polymer/UiO-66(Zr) and Polymer/NaY Fiber Sorbents for Mercaptan Removal from Natural Gas.

    Science.gov (United States)

    Chen, Grace; Koros, William J; Jones, Christopher W

    2016-04-20

    Zeolite NaY and metal organic frameworks MIL-53(Al) and UiO-66(Zr) are spun with cellulose acetate (CA) polymer to create hybrid porous composite fibers for the selective adsorption of sulfur odorant compounds from pipeline natural gas. Odorant removal is desirable to limit corrosion associated with sulfur oxide production, thereby increasing lifetime in gas turbines used for electricity generation. In line with these goals, the performance of the hybrid fibers is evaluated on the basis of sulfur sorption capacity and selectivity, as well as fiber stability and regenerability, compared to their polymer-free sorbent counterparts. The capacities of the powder sorbents are also measured using various desorption temperatures to evaluate the potential for lower temperature, energy, and cost-efficient system operation. Both NaY/CA and UiO-66(Zr)/CA hybrid fibers are prepared with high sorbent loadings, and both have high capacities and selectivities for t-butyl mercaptan (TBM) odorant sorption from a model natural gas (NG), while being stable to multiple regeneration cycles. The different advantages and disadvantages of both types of fibers relative are discussed, with both offering the potential advantages of low pressure drop, rapid heat and mass transfer, and low energy requirements over traditional sulfur removal technologies such as hydrodesulfurization (HDS) or adsorption in a pellet packed beds.

  4. Mercury separation from concentrated potassium iodide/iodine leachate using Self-Assembled Mesoporous Mercaptan Support (SAMMS) technology

    International Nuclear Information System (INIS)

    Mattigod, S.V.; Feng, X.; Fryxell, G.E.

    1997-10-01

    A study was conducted to demonstrate the effectiveness of a novel adsorber, the Self-Assembled Mesoporous Mercaptan Support (SAMMS) material to remove mercury (Hg) from potassium iodide/iodine (KI/I 2 ) waste streams. This study included investigations of the SAMMS material''s binding kinetics, loading capacity, and selectivity for Hg adsorption from surrogate and actual KI/I 2 waste solutions. The kinetics data showed that binding of Hg by the adsorber material occurs very rapidly, with 82% to 95% adsorption occurring within the first 5 min. No significant differences in the rate of adsorption were noted between pH values of 5 and 9 and at Hg concentrations of ∼100 mg/1. Within the same range of pH values, an approximate four-fold increase in initial Hg concentration resulted in a two-fold increase in the rate of adsorption. In all cases studied, equilibrium adsorption occured within 4 h. The loading capacity experiments in KI/I 2 surrogate solutions indicated Hg adsorption densities between 26 to 270 mg/g. The loading density increased with increasing solid: solution ratio and decreasing iodide concentrations. Values of distribution coefficients (1.3x10 5 to >2.6x10 8 ml/g) indicated that material adsorbs Hg with very high specificity from KI/I 2 surrogate solutions. Reduction studies showed that compared to metallic iron (Fe), sodium dithionite can very rapidly reduce iodine as the triiodide species into the iodide form. Adsorption studies conducted with actual KI/I 2 leachates confirmed the highly specific Hg adsorption properties (K d >6x10 7 to>1x10 8 ml//g) of the adsorber material. Following treatment, the Hg concentrations in actual leachates were below instrumental detection limits (i.e., < 0.00005 mg/l), indicating that the KI solutions can be recycled

  5. CH3SH adsorption properties and mechanism of deodorant filter made of iron hydroxide on porous iron frame; Tetsu takotaisei dasshu filter no methyl mercaptan jokyo seino to jokyo kiko

    Energy Technology Data Exchange (ETDEWEB)

    Noda, T. [Nippon Steel Corp., Tokyo (Japan)

    1998-05-10

    It is suggested that methyl mercaptan is decomposed to methyl sulfide and hydrogen by reaction with the a-iron hydroxide, and then the methyl sulfide combines with sulfur crystal and the hydrogen changes into water by the chemical reaction with the {alpha}-iron hydroxide. A deodorant filter was made by treating porous metallic iron with an aqueous solution of L-ascorbic acid, iron (II) sulfate and calcium hydroxide aqueous solution to deposit the iron ascorbate and the {alpha}-iron hydroxide on it. Then the deodorant filter was exposed to the hydrogen sulfide to yield the sulfur crystals on the surface of the deodorant filter. The methyl mercaptan removal capacity of the deodorant filter was studied with repetition of removal tests. Results show that the methyl mercaptan removal capacity of the deodorant filter is a little smaller than that of conventional granular activated carbon. 6 refs., 6 figs., 3 tabs.

  6. The method for on-site determination of trace concentrations of methyl mercaptan and dimethyl sulfide in air using a mobile mass spectrometer with atmospheric pressure chemical ionization, combined with a fast enrichment/separation system.

    Science.gov (United States)

    Kudryavtsev, Andrey S; Makas, Alexey L; Troshkov, Mikhail L; Grachev, Mikhail А; Pod'yachev, Sergey P

    2014-06-01

    A method for fast simultaneous on-site determination of methyl mercaptan and dimethyl sulfide in air was developed. The target compounds were actively collected on silica gel, followed by direct flash thermal desorption, fast separation on a short chromatographic column and detection by means of mass spectrometer with atmospheric pressure chemical ionization. During the sampling of ambient air, water vapor was removed with a Nafion selective membrane. A compact mass spectrometer prototype, which was designed earlier at Trofimuk Institute of Petroleum Geology and Geophysics, was used. The minimization of gas load of the atmospheric pressure ion source allowed reducing the power requirements and size of the vacuum system and increasing its ruggedness. The measurement cycle is about 3 min. Detection limits in a 0.6 L sample are 1 ppb for methyl mercaptan and 0.2 ppb for dimethyl sulfide. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Micro-oxygenation does not eliminate hydrogen sulfide and mercaptans from wine; it simply shifts redox and complex-related equilibria to reversible oxidized species and complexed forms.

    Science.gov (United States)

    Vela, Eduardo; Hernandez-Orte, Purificación; Franco-Luesma, Ernesto; Ferreira, Vicente

    2018-03-15

    This work seeks to assess the effects of micro-oxygenation (MOX) on the present and potential levels of Volatile Sulfur Compounds (VSCs) of wine. With such purpose, three red wines with a tendency to develop sulfury off-odors were subjected to three different MOX conditions (4.4-20mg/L delivered at 0.05 or 0.2mg/L/day). Samples were further subjected to Accelerated Reductive aging (AR) and analyzed for free and Brine Releasable (BR) VSCs and redox potential. Although MOX induced strong decreases in the levels of all free VSCs, hardly affected the ability of the wine to release back hydrogen sulfide and other mercaptans during AR-aging. During aging BR-levels of MOX samples became in most cases similar or higher than non-oxygenated controls. BR-levels and the fractions free/BR follow characteristic sigmoid plots when represented versus redox potential suggesting that all changes are the result of reversible equilibria between free, metal-complexed and oxidized forms of VSCs. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Sensors based on Ag-loaded hematite (α-Fe2O3 nanoparticles for methyl mercaptan detection at room temperature

    Directory of Open Access Journals (Sweden)

    Daniel Garcia

    2017-06-01

    Full Text Available Sensors based on Ag/α-Fe2O3 nanoparticles have been prepared by the coprecipitation method for sensing methyl mercaptan at room temperature. X-ray diffraction patterns of samples matched perfectly with characteristic peaks of hematite with no peaks assigned to Ag even at the highest concentration. STEM images and EDX analysis revealed the presence of Ag nanoparticles (from 2 to 5 nm which were highly dispersed onto α-Fe2O3 surface with an Ag/Fe ratio from 0.014 to 0.099. The Ag nanoparticles were deposited on the hematite surface. Sensing tests of Ag-loaded hematite nanoparticles showed much higher response signal than the unmodified sensor. Hematite loaded with 3%(Wt Ag showed the highest response with a linear dependence from 20 to 80 ppm. The sensor also depicted a good selectivity and stability during 4 days with short recovery time. The high dispersion of reduced Ag evaluated by XPS analysis played an important chemical role in the sensing mechanism that favored the contact of CH3SH with oxygen.

  9. Preparação de fibras de polipropileno modificadas com grupos mercaptan e sua utilização em compósitos com resina epoxídica

    Directory of Open Access Journals (Sweden)

    Dutra Rita C. L.

    1999-01-01

    Full Text Available Fibras de polipropileno modificadas com grupos mercaptan foram desenvolvidas através de processo de extrusão/fiação de misturas contendo PP e EVA modificado com grupos mercaptan (EVASH. A superfície destas fibras foi analisada por espectroscopia foto-eletrônica de raios-X (XPS, espectroscopia no infravermelho com transformada de Fourier, utilizando-se a técnica de refletância difusa (DRIFTS, tensão superficial e microscopia eletrônica de varredura. A partir destas técnicas, chegou-se à conclusão que o componente polar (EVASH se situa próximo à superfície da fibra. A utilização destas fibras em compósitos com resina epoxídica resultou em aumento considerável da resistência ao impacto e da temperatura de transição vítrea do material, indicando boa adesão interfacial matriz-fibra. Estas interações foram comprovadas por análise dinâmico-mecânicas.

  10. Factors Influencing Degradation of Mercaptans by Thiobacillus ...

    African Journals Online (AJOL)

    MICHAEL

    Sundman, 1975). Little work has been published on the microbial degradation of other thiols with the exception of methanethiol. The biogenesis of methylsulphides provides a principal input of volatile sulphur to the atmosphere. This contribution has significant effects on the sulphur cycle and on global geochemistry (Taylor.

  11. Factors Influencing Degradation of Mercaptans by Thiobacillus ...

    African Journals Online (AJOL)

    Degradation of methylmercaptans by Thiobacillus thioparus TK-m was influenced by pH of the reaction medium. Ratios of headspace concentrations in empty vials and those of acidified buffer solutions were less than 1.0. 95% of the H2S was in headspace with the remaining 5% in solution upon acidification. The values for ...

  12. Comportamento de cura de adesivo epoxídico contendo grupo mercaptana avaliado por espectroscopia no infravermelho (MIR/NIR e calorimetria exploratória diferencial (DSC Cure behavior of epoxy adhesive containig mercaptan group evaluated by infrared spectroscopy (MIR/NIR and differential scanning calorimetry (DSC

    Directory of Open Access Journals (Sweden)

    Hilzette P. C. Andrade

    2008-01-01

    Full Text Available No presente trabalho, a flexibilidade de um adesivo epoxídico contendo diglicidiléter de bisfenol A (DGEBA e dietilenotriamina (DETA como agente de cura foi modificada pela adição de um segundo componente contendo grupos mercaptana (CAPCURE. A adição de amianto ao adesivo contendo CAPCURE também foi avaliada. As reações entre os grupos epoxídicos e os grupos amina, assim como entre os grupos epoxídicos e os grupos mercaptana, foram estudadas nas regiões espectrais do infravermelho médio (MIR e próximo (NIR. Observou-se que o amianto não interfere nas reações de cura e que a espectroscopia FT-NIR evidencia melhor as alterações espectrométricas ocorridas durante as reações em relação à análise FT-MIR. O tempo das reações de cura foi monitorado por calorimetria exploratória diferencial (DSC, observando-se que a introdução do CAPCURE acelerou a cura da resina. A energia de ativação (Ea das reações de cura foi obtida pelos métodos de Barrett e Borchardt-Daniels. Os adesivos contendo CAPCURE mostraram Ea em torno de 30 kJ.mol-1, enquanto o adesivo DGEBA/DETA apresentou Ea de 46 kJ.mol-1, ambas calculadas pelo método de Barrett.In the present work, the flexibility of an epoxy adhesive containing diglycidylether of bisphenol-A (DGEBA and diethylenetriamine (DETA as curing agent was changed by the addition of a second component containing mercaptan groups (CAPCURE. The addition of asbestos as a filler in the adhesive containing CAPCURE was also evaluated. Epoxy-amine and epoxy-mercaptan reactions were studied in NIR and MIR spectral regions. The filler addition did not cause influence on the cure reactions and spectrometric changes of cure reactions could be better observed by FT-NIR than FT-MIR analysis. The cure reaction time was monitored by DSC experiments and it was observed that the introduction of CAPCURE accelerated the cure reaction. The activation energies (Ea of curing reactions were obtained using Barrett

  13. Plasmas pour la destruction de l'H2S et des mercaptans Plasmas for Destruction of H2s and Mercaptans

    Directory of Open Access Journals (Sweden)

    Czernichowski A.

    2006-12-01

    Full Text Available Cet article passe en revue l'utilisation des plasmas comme milieu activateurs d'une oxydation de H2S ou CH3SH dilués dans l'air, le CO2 ou la vapeur d'eau, à fins de conversion en SO, moins malodorant. Le produit peut être ensuite utilisé comme réactif dans un processus similaire à celui de Claus, en présence d'eau, ce qui permet de convertir deux fois plus de polluants initiaux en soufre élémentaire. Une attention particulière est portée aux décharges électriques glissantes (GlidArc. Ces décharges puissantes produisent un plasma non thermique qui active des réactions oxydatrices. La plupart des expériences ont été réalisées en utilisant les réacteurs GlidArc-I à un ou à quatre étages. Les sulfures dilués dans l'air dans des concentrations initiales atteignant jusqu'à 1 %( H2S ou 0,1 % (CH3SH ont été traités sous des flux jusqu'à 70 m3(n/h d'air pollué et sous une puissance de 5 kW. Les essais ont été réalisés sous 1 atm. Une dépollution jusqu'à 100 % a été obtenue moyennant un coût énergétique assez bas dépendant de la concentration initiale du polluant : environ 1000 kWh par kilogramme de soufre extrait pour 100 ppm de H2S et seulement 10 kWh/kg pour 1 % initial d'H2S dans l'air. Pratiquement les mêmes coûts ont été observés dans le cas de mélanges CH3SH-air. En utilisant une très simple douche en recirculation d'eau qui lave les gaz sortants (l'eau se sature avec le SO2 et capture ainsi l'H2S non traité nous avons divisé ces coûts d'énergie par trois, en évitant également l'émission de SO2, et en obtenant du soufre non toxique. Un nouveau principe (et réacteur GlidArc-II est ensuite présenté ; il s'agit d'une brosseà décharges électriques. Nos premiers tests sont très prometteurs car dès à présent, nous divisons déjà la dépense énergétique par deux par rapport au GlidArc-I. L'échelle industrielle peut par conséquent être envisagée. Plasmas are reviewed as activation media for an oxidation of H2S or CH3SH diluted in air, CO2 or steam in order to convert them into less malodorous SO2. The product can be then used as a reagent in a Claus-like process in presence of water to convert twice as much of initial pollutants into elemental sulfur. A particular attention is devoted to the gliding electrical discharges (GlidArc. These powerful discharges produce non-thermal plasma, which activates oxidation reactions. Most of experiments were performed using one and four-stage GlidArc-I reactors. Air-diluted sulfides at initial concentrations up to 1% (H2S or 0. 1% (CH3SH were processed at up to 70 m3(n/h flow rate and 5 kW power scale. The tests were done at 1 atm. Up to 100% clean-up was obtained at a quite low energy cost depending on initial pollutant concentration: roughly 1000 kWh per 1 kg of removed sulfur at 100 ppm of H2S, but only 10 kWh/kg for 1% initial H2S in air. Almost the same energies were needed in the case of CH3SH-air mixtures. Using a very simple washing column in which water saturates with the produced SO2 and so captures unprocessed H2S we cut these process energy by three, avoiding the SO2 emission and obtaining non-toxic sulfur. New development based on GlidArc-ll brush-like electric discharges is also presented. Preliminary tests are very promising as the energy expense is already cut down by a factor of two with respect to the GlidArc-I devices. Up to industrial scale tests can be therefore performed.

  14. Micromechanical assessment of PMMA microcapsules containing epoxy and mercaptan as self-healing agents

    NARCIS (Netherlands)

    Ahangaran, Fatemeh; Hayaty, Mehran; Navarchian, Amir H.; Picchioni, Francesco

    2017-01-01

    Mechanical properties of microcapsule shell have great influence on microcapsule suitability as a mechanical trigger in a self-healing composite. The elastic modulus and hardness of polymethyl methacrylate (PMMA) microcapsules containing epoxy prepolymer (EC 157) and pentaerythritol tetrakis

  15. Appropriate sample bags and syringes for preserving breath samples in breath odor research : a technical note

    NARCIS (Netherlands)

    Winkel, E. G.; Tangerman, A.

    It is now generally accepted that the volatile sulfur compounds (VSCs) hydrogen sulfide, methyl mercaptan and dimethyl sulfide are the main contributors to halitosis when of oropharyngeal origin. The VSCs hydrogen sulfide and methyl mercaptan are the major causes of bad breath in oral malodour

  16. Uses of Tc99m complexes

    International Nuclear Information System (INIS)

    Kubiatowicz, D.O.; Bolles, T.F.

    1978-01-01

    The invention deals with the use of a complex of the radioactive metastable isotope Tcsup(99m) together with water-soluble mercaptane for the preparation of a parenterally administered renal diagnostic agent. (VJ/orig.) [de

  17. Hydrogen-transfer and charge-transfer in photochemical and radiation induced reactions. Progress report, November 1, 1975--October 31, 1976

    International Nuclear Information System (INIS)

    Cohen, S.G.

    1976-10-01

    The relative importance of light absorption, quenching of triplet, and hydrogen transfer repair has been examined in retardation by mercaptans of photoreduction of aromatic ketones by alcohols. In the reduction of benzophenone by 2-propanol, retardation is efficient and, after correction for the first two effects, is due entirely to hydrogen-transfer repair, as indicated by deuterium labeling. In reduction of acetophenone by α-methylbenzyl alcohol, repair by hydrogen transfer is also operative. In reduction of benzophenone by benzhydrol, retardation is less efficient and is due to quenching, as the ketyl radical does not abstract hydrogen from mercaptan rapidly in competition with coupling. Deuterium isotope effects are discussed in terms of competitive reactions. Photoreduction of benzophenone by 2-butylamine and by triethylamine is retarded by aromatic mercaptans and disulfides. Of the retardation not due to light absorption and triplet quenching by the sulfur compounds, half is due to hydrogen-transfer repair, as indicated by racemization and deuterium labeling. The remainder is attributed to quenching by the sulfur compound of the charge-transfer-complex intermediate. Photoreduction by primary and secondary amines, but not by tertiary amines, is accelerated by aliphatic mercaptans. The acceleration is attributed to catalysis of hydrogen transfer by the mercaptan in the charge-transfer complex. The effect is large in hydrocarbon solvent, less in polar organic solvents and absent in water

  18. Deodorizing Substance in Black Cumin (Nigella sativa L.) Seed Oil.

    Science.gov (United States)

    Nakasugi, Toru; Murakawa, Takushi; Shibuya, Koji; Morimoto, Masanori

    2017-08-01

    A deodorizing substance in black cumin (Nigella sativa L.), a spice for curry and vegetable foods in Southwest Asia, was examined. The essential oil prepared from the seeds of this plant exhibited strong deodorizing activity against methyl mercaptan, which is a main factor in oral malodor. After purification with silica gel column chromatography, the active substance in black cumin seed oil was identified as thymoquinone. This monoterpenic quinone functions as the main deodorizing substance in this oil against methyl mercaptan. Metabolite analysis suggested that the deodorizing activity may be generated by the addition of a reactive quinone molecule to methyl mercaptan. In the present study, the menthane-type quinone and phenol derivatives exhibited deodorizing activities via this mechanism.

  19. Apparatus and method for production of methanethiol

    Science.gov (United States)

    Agarwal, Pradeep K.; Linjewile, Temi M.; Hull, Ashley S.; Chen, Zumao

    2006-02-07

    A method for the production of methyl mercaptan is provided. The method comprises providing raw feed gases consisting of methane and hydrogen sulfide, introducing the raw feed gases into a non-thermal pulsed plasma corona reactor, and reacting the raw feed gases within the non-thermal pulsed plasma corona reactor with the reaction CH4+H2S.fwdarw.CH3SH+H2. An apparatus for the production of methyl mercaptan using a non-thermal pulsed plasma corona reactor is also provided.

  20. Deodorization and dearomatization of kerosene by liquid extraction ...

    African Journals Online (AJOL)

    Sulphur compounds determination was by the Nickel Reduction Method. The specific gravity, aromatic content, smoke point, flash point, mercaptan sulphur, initial and end boiling points and the k-factor of the kerosene were determined using standard procedures. Also the distribution of sulphur compounds in distillation ...

  1. SUPPLEMENTARY INFORMATION

    Indian Academy of Sciences (India)

    Saket

    amines and o-amino/mercaptan/hydroxyanilines: Elemental sulfur as a highly efficient and traceless oxidizing agent Org. Lett. 14 5948. 2. Mayo M S, Yu X, Zhou X, Feng X, Yamamoto Y, Bao M 2014 Convenient synthesis of benzothiazoles and benzimidazoles through brønsted acid catalyzed cyclization of 2-amino.

  2. Galloylated proanthocyanidins from shea (Vitellaria paradoxa) meal have potent anthelmintic activity against Ascaris suum

    DEFF Research Database (Denmark)

    Ramsay, A; Williams, A R; Thamsborg, S M

    2016-01-01

    Proanthocyanidins (PA) from shea (Vitellaria paradoxa) meal were investigated by thiolytic degradation with benzyl mercaptan and the reaction products were analysed by high performance liquid chromatography-mass spectrometry. These PA were galloylated (≈40%), contained only B-type linkages and had...

  3. Photodissociation dynamics of ethanethiol in clusters: complementary information from velocity map imaging, mass spectrometry and calculations

    Czech Academy of Sciences Publication Activity Database

    Svrčková, Pavla; Pysanenko, Andriy; Lengyel, Jozef; Rubovič, Peter; Kočišek, Jaroslav; Poterya, Viktoriya; Slavíček, Petr; Fárník, Michal

    2015-01-01

    Roč. 17, č. 39 (2015), s. 25734-25741 ISSN 1463-9076 R&D Projects: GA ČR GA14-14082S; GA ČR GA14-08937S Institutional support: RVO:61388955 Keywords : POTENTIAL-ENERGY SURFACES * METHYL MERCAPTAN * CONICAL INTERSECTIONS Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.449, year: 2015

  4. The sulfurous compounds consisting of hydrocarbon fuels

    Directory of Open Access Journals (Sweden)

    Т.В. Медвєдєва

    2004-04-01

    Full Text Available  The sulfurous compounds have been studied and their negative influence on operation properties of the oil and products of its processing have been described. Basic methods of definition of the hydrogen sulphide, mercaptans in the hydrocarbon fuels have been shown.

  5. Author Details

    African Journals Online (AJOL)

    Adoki, A. Vol 6, No 2 (2002) - Articles Culture characteristics of Candida sp in waste conversion: implications for single-cell- protein-enriched feed supplement production. Abstract PDF · Vol 11, No 3 (2007) - Articles Factors Influencing Degradation of Mercaptans by Thiobacillus thioparus TK-m (1) Abstract PDF · Vol 11, No ...

  6. [Inhibitory effect on Microcystis aeruginosa as well as separation and identification of the allelochemicals of welsh onion].

    Science.gov (United States)

    Zhou, Yang; Li, Yuan; Li, Cheng; Liu, Lu; Zhang, Tingting

    2013-11-01

    To study the inhibition of welsh onion on Microcystis aeruginosa, and separat and identify of the allelochemicals from welsh onion. METHEDS: The inhibitory effect of different concentrations of fistular onion stalk and fistular onion leaf water extracts on M. aeruginosa were studied; besides, separation and identification of the allelochemicals of welsh onion were also studied. Both fistular onion stalk and fistular onion leaf water extracts had, to different degree, inhibitory effect on the growth of M. aeruginosat. Compared with the control group, the fluorescence intensity of fistular onion stalk and fistular onion leaf were lower than the control group in the same period, and the inhibitory effect were more obvious with the increase of the water extract concentrations, to the fifth day, M. aeruginosa almost completely dead of the highest concentration(50 ml/L) of fistular onion stalk water extract treated group, the EC50 of water extract from fistular onion stalk to M. aeruginosa was 12.7 ml/L, equivalent to fresh weight 1.27 g/L. Main allelochemicals in fistular onion stalk includes allyl mercaptan, cyclopentyl mercaptan, and so on. The inhibiting assay on M. aeruginosa showed that the EC50 of allyl mercaptan and cyclopentyl mercaptan respectively were 0.03 and 0.02 g/L. The fistular onion stalk water extracts has very good algicidal effect, allelopathic algal inhibiting substances primarily are sulfocompound, which have the potential to develop into biological algicide.

  7. Photodegradation of odorous 2-mercaptobenzoxazole through zinc oxide/hydroxyapatite nanocomposite

    DEFF Research Database (Denmark)

    Buazar, Foad; Alipouryan, S.; Kroushawi, Feisal

    2015-01-01

    In this study, ZnO/HAP nanocomposite with excellent photocatalytic activities was successfully synthesized by sol–gel method and used for degradation of 2-mercaptobenzoxazole (MBO) as model of odorous mercaptan compound in water. To optimize the performance of ZnO/HAP photocatalytic capabilities,...

  8. 40 CFR Appendix A to Part 414 - Non-Complexed Metal-Bearing Waste Streams and Cyanide-Bearing Waste Streams

    Science.gov (United States)

    2010-07-01

    ... Mercaptan/Ethanol + Hydrogen sulfide Methanol/H.P. Synthesis from natural gas via synthetic gas Oxo Alcohols... + Ammonia n-Propyl alcohol/Hydrogenation of propionaldehyde, Oxo process SAN resin/Suspension polymerization.../High pressure synthesis from natural gas via synthetic gas Methanol/Low pressure synthesis from natural...

  9. Electrochemical generation of fentons reagent to treat spent caustic wastewater

    International Nuclear Information System (INIS)

    Hansen, H. K.; Nunez, P.; Rodriguez, N.; Guzman, J.

    2009-01-01

    An important wastewater stream from oil refineries is the spent caustic. Caustic solutions are used as scrubbing agent during the desulphurization process to eliminate sulphur an mercaptans from oil and gasses. Spent caustic is classified as DOO3 (reactive sulphide) hazardous waste under the US Resource Conservation and Recovery Act (RCRA). (Author)

  10. Kinetics of aerobic oxidation of volatile sulfur compounds in wastewater and biofilm from sewers

    DEFF Research Database (Denmark)

    Rudelle, Elise Alice; Vollertsen, Jes; Hvitved-Jacobsen, Thorkild

    2013-01-01

    -spot downstream of a force main and the other was a gravity sewer transporting young aerobic wastewater. The kinetics of VSC oxidation for both wastewater and suspended biofilm samples followed a first-order rate equation. The average values of the reaction rate constants demonstrated the following order......Laboratory experiments were conducted to investigate the kinetics of aerobic chemical and biological oxidation of selected odorous volatile sulfur compounds (VSCs) by wastewater and biofilm from sewers. The VSCs included methyl mercaptan (MeSH), ethyl mercaptan (EtSH), dimethyl sulfide (DMS...... of reactivity: total inorganic sulfide >EtSH≥MeSH>>DMS. Except for total inorganic sulfide oxidation in wastewater, kinetic parameters for each VSC were of similar magnitude for the two locations. In the wastewater from the odor hot-spot, sulfide inorganic oxidation rates were approximately 12 times faster than...

  11. Biogas--municipal solid waste incinerator bottom ash interactions: sulphur compounds removal.

    Science.gov (United States)

    Ducom, Gaëlle; Radu-Tirnoveanu, Daniela; Pascual, Christophe; Benadda, Belkacem; Germain, Patrick

    2009-07-30

    This study focuses on a new way of reusing municipal solid waste incinerator bottom ash: landfill gas purification before energetic valorisation. A pilot plant was designed and operated on a landfill site located in France (Loire). One kilogram bottom ash is able to sequestrate more than 3.0 g of hydrogen sulphide, 44 mg of methyl mercaptan, and 86 mg of dimethyl sulphide. Hydrogen sulphide retention is probably due to acid-basic reactions conducting to sulphur mineralisation under the form of low solubility metal sulphides. The reaction medium is hydration water. The retention mechanism for methyl mercaptan is probably similar but dimethyl sulphide is most likely retained by physical adsorption. As methane is not retained by bottom ash, the landfill gas energetic content will not be lowered. There seems to be no appreciable difference in these results whether bottom ash is fresh or carbonated. These results are encouraging in the perspective of a field scale application of this biogas treatment process.

  12. Uptake and utilization of sulfonic acids in the cyanobacterial strains Anabaena variabilis and Plectonema 73110

    International Nuclear Information System (INIS)

    Biedlingmaier, S.; Schmidt, A.

    1987-01-01

    Growth of several cyanobacteria was examined on ethane sulfonate and taurine as only sulfur source. Comparing two strains with differential utilization of sulfonic acids (Anabaena variabilis and Synechococcus 6301) demonstrated that actual growth was coupled to the presence of an active sulfonate transport system due to species specific properties and nutritional conditions. Sulfonate uptake in Anabaena variabilis was characterized by a pH optimum of 6.5, a structural specificity for sulfonates, missing Na + dependence, and phosphate stimulation. Radiolabeled ethane sulfonate and taurine was metabolized to products of normal sulfur metabolism. Also considerable amounts of 35 S-labeled volatiles (mercaptanes and sulfide) could be detected, suggesting a degradation mechanism via reduction to mercaptanes and cleavage of the C-S bond. (orig.)

  13. High frequency transformers and high Q factor inductors formed using epoxy-based magnetic polymer materials

    Science.gov (United States)

    Sanchez, Robert O.; Gunewardena, Shelton; Masi, James V.

    2005-03-29

    An electrical component in the form of an inductor or transformer is disclosed which includes one or more coils and a magnetic polymer material located near the coils or supporting the coils to provide an electromagnetic interaction therewith. The magnetic polymer material is preferably a cured magnetic epoxy which includes a mercaptan derivative having a ferromagnetic atom chemically bonded therein. The ferromagnetic atom can be either a transition metal or rare-earth atom.

  14. Sulfide chemiluminescence detection

    Science.gov (United States)

    Spurlin, S.R.; Yeung, E.S.

    1985-11-26

    A method is described for chemiluminescently determining a sulfide which is either hydrogen sulfide or methyl mercaptan by reacting the sulfide with chlorine dioxide at low pressure and under conditions which allow a longer reaction time in emission of a single photon for every two sulfide containing species, and thereafter, chemiluminescently detecting and determining the sulfide. The invention also relates not only to the detection method, but the novel chemical reaction and a specifically designed chemiluminescence detection cell for the reaction. 4 figs.

  15. Apparatus for use in sulfide chemiluminescence detection

    Science.gov (United States)

    Spurlin, S.R.; Yeung, E.S.

    1987-01-06

    A method is described for chemiluminescently determining a sulfide which is either hydrogen sulfide or methyl mercaptan by reacting the sulfide with chlorine dioxide at low pressure and under conditions which allow a longer reaction time in emission of a single photon for every two sulfide containing species, and thereafter, chemiluminescently detecting and determining the sulfide. The invention also relates not only to the detection method, but the novel chemical reaction and a specifically designed chemiluminescence detection cell for the reaction. 4 figs.

  16. 40 CFR 60.489 - List of chemicals produced by affected facilities.

    Science.gov (United States)

    2010-07-01

    ... Aminoethylethanolamine. 123-30-8 p-Aminophenol. 628-63-7, 123-92-2 Amyl acetates. 71-41-0 c Amyl alcohols. 110-58-7 Amyl amine. 543-59-9 Amyl chloride. 110-66-7 c Amyl mercaptans. 1322-06-1 Amyl phenol. 62-53-3 Aniline. 142...-4 Bromonaphthalene. 106-99-0 Butadiene. 106-98-9 1-butene. 123-86-4 n-butyl acetate. 141-32-2 n...

  17. Solid phase extraction-preconcentration and high performance liquid chromatographic determination of 2-mercapto-(benzothiazole, benzoxazole and benzimidazole) using copper oxide nanoparticles.

    Science.gov (United States)

    Parham, Hooshang; Khoshnam, Farzaneh

    2013-09-30

    This study introduces a novel method of solid phase extraction (SPE), preconcentration and HPLC determination of 2-mercaptobenzimidazole (2MBI), 2-mercaptobenzoxazole (2MBO) and 2-mercaptobenzothiazole (2MBT) from an aqueous solution by a SPE cartridge loaded with copper oxide nanoparticles. Results demonstrated that copper oxide nanoparticles are quite efficient for extraction and preconcentration of trace amounts of these mercaptans at room temperature. The study also investigated the effects of parameters such as pH, buffer and its volume, electrolyte concentration, flow rate of the test solution, composition and volume of the desorbing solvent, accepted tolerable volume, amount of adsorbent, reusability of cartridges and evidence of some co-existing species on extraction and determination of the above mentioned mercaptans. The method showed good linearity for determination of these mercaptans in the range of 0.01-10 μg mL(-1) with regression coefficients better than 0.9969. The limits of detection (LODs) evaluations were 0.0021, 0.0027 and 0.0019 μg mL(-1) for 2MBT, 2MBO and 2MBI, respectively. The relative standard deviations (RSDs) for 0.2 μg mL(-1) and 5 μg mL(-1) of the measured mercaptans were below 3.04% and 4.23%, respectively. Ramin Power Plant (3000 MW, Ahvaz, Iran) cooling water containing some 2MBT (as corrosion inhibitor) was used as the real sample. Recovery tests with spiked levels of 2MBT, 2MBI and 2MBO were carried out and satisfied results were obtained. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Nickel-Catalyzed C-S Bond Formation via Decarbonylative Thioetherification of Esters, Amides and Intramolecular Recombination Fragment Coupling of Thioesters

    KAUST Repository

    Lee, Shao-Chi

    2018-01-15

    A nickel catalyzed cross-coupling protocol for the straightforward C-S bond formation has been developed. Various mercaptans and a wide range of ester and amide substrates bearing various substituents were tolerated in this process which afforded products in good to excellent yields. Furthermore, an intramolecular protocol for the synthesis of thioethers starting from thioesters has been developed. The utility of this protocol has been demonstrated in the synthesis of benzothiophene on the bench top.

  19. Adsorptive removal of sulfur compounds using IRMOF-3 at ambient temperature

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiao-Ling [Key Laboratory of Coal Science and Technology, Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024 (China); Fan, Hui-Ling, E-mail: fanhuiling@tyut.edu.cn [Key Laboratory of Coal Science and Technology, Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024 (China); Tian, Zhen [Shanghai Second Polytechnic University, Shanghai 201209 (China); He, En-Yun; Li, Ye; Shangguan, Ju [Key Laboratory of Coal Science and Technology, Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024 (China)

    2014-01-15

    Zinc-based metal–organic framework (IRMOF-3) was used as adsorbent for removal of dimethyl sulfide, ethyl mercaptan and hydrogen sulfide in fixed bed reactor at ambient temperature. These samples before and after exposure to sulfur compounds were characterized by Fourier transform infrared (FTIR), and X-ray diffraction (XRD), and thermo gravimetric (TG), and X-ray photoelectron spectroscopy (XPS). The results show that IRMOF-3 exhibit the best performance for hydrogen sulfide removal with the highest breakthrough sulfur capacity, followed by ethyl mercaptan and dimethyl sulfide. This is in consistent with the interaction strength between IRMOF-3 and sulfur compounds. In the case of dimethyl sulfide and ethyl mercaptan, the interaction comes from the weak interaction between the amino group in the MOFs and the sulfur atom of the adsorbate. This can also be considered as a hydrogen bond complex in which the amino group in the MOFs and the S atom of the sulfur compounds play the role of H-donor and H-acceptor, respectively. In the case of hydrogen sulfide, the interaction with sulfur atom originates from the amino group and zinc site in the MOFs. The former is more like an acid–base interaction, whereas the latter results in new products of ZnS and H{sub 2}O and serious destruction of the MOFs.

  20. Adsorptive removal of sulfur compounds using IRMOF-3 at ambient temperature

    Science.gov (United States)

    Wang, Xiao-Ling; Fan, Hui-Ling; Tian, Zhen; He, En-Yun; Li, Ye; Shangguan, Ju

    2014-01-01

    Zinc-based metal-organic framework (IRMOF-3) was used as adsorbent for removal of dimethyl sulfide, ethyl mercaptan and hydrogen sulfide in fixed bed reactor at ambient temperature. These samples before and after exposure to sulfur compounds were characterized by Fourier transform infrared (FTIR), and X-ray diffraction (XRD), and thermo gravimetric (TG), and X-ray photoelectron spectroscopy (XPS). The results show that IRMOF-3 exhibit the best performance for hydrogen sulfide removal with the highest breakthrough sulfur capacity, followed by ethyl mercaptan and dimethyl sulfide. This is in consistent with the interaction strength between IRMOF-3 and sulfur compounds. In the case of dimethyl sulfide and ethyl mercaptan, the interaction comes from the weak interaction between the amino group in the MOFs and the sulfur atom of the adsorbate. This can also be considered as a hydrogen bond complex in which the amino group in the MOFs and the S atom of the sulfur compounds play the role of H-donor and H-acceptor, respectively. In the case of hydrogen sulfide, the interaction with sulfur atom originates from the amino group and zinc site in the MOFs. The former is more like an acid-base interaction, whereas the latter results in new products of ZnS and H2O and serious destruction of the MOFs.

  1. Adsorption/oxidation of sulfur-containing gases on nitrogen-doped activated carbon

    Directory of Open Access Journals (Sweden)

    Liu Qiang

    2016-01-01

    Full Text Available Coconut shell-based activated carbon (CAC was used for the removal of methyl mercaptan (MM. CAC was modified by urea impregnation and calcined at 450°C and 950°C. The desulfurization activity was determined in a fixed bed reactor under room temperature. The results showed that the methyl mercaptan adsorption/oxidation capacity of modified carbon caicined at 950°C is more than 3 times the capacity of original samples. On the other hand, the modified carbon caicined at 950°C also has a high capacity for the simultaneous adsorption/oxidation of methyl mercaptan and hydrogen sulfide.The introduce of basic nitrogen groups siginificantly increases the desulfurization since it can facilitate the electron transfer process between sulfur and oxygen. The structure and chemical properties are characterized using Boehm titration, N2 adsorption-desorption method, thermal analysis and elemental analysis. The results showed that the major oxidation products were dimethyl disulfide and methanesulfonic acid which adsorbed in the activated carbon.

  2. Methane oxidation and attenuation of sulphur compounds in landfill top cover systems: Lab-scale tests.

    Science.gov (United States)

    Raga, Roberto; Pivato, Alberto; Lavagnolo, Maria Cristina; Megido, Laura; Cossu, Raffaello

    2018-03-01

    In this study, a top cover system is investigated as a control for emissions during the aftercare of new landfills and for old landfills where biogas energy production might not be profitable. Different materials were studied as landfill cover system in lab-scale columns: mechanical-biological pretreated municipal solid waste (MBP); mechanical-biological pretreated biowaste (PB); fine (PBS f ) and coarse (PBS c ) mechanical-biological pretreated mixtures of biowaste and sewage sludge, and natural soil (NS). The effectiveness of these materials in removing methane and sulphur compounds from a gas stream was tested, even coupled with activated carbon membranes. Concentrations of CO 2 , CH 4 , O 2 , N 2 , H 2 S and mercaptans were analysed at different depths along the columns. Methane degradation was assessed using mass balance and the results were expressed in terms of methane oxidation rate (MOR). The highest maximum and mean MOR were observed for MBP (17.2gCH 4 /m 2 /hr and 10.3gCH 4 /m 2 /hr, respectively). Similar values were obtained with PB and PBS c . The lowest values of MOR were obtained for NS (6.7gCH 4 /m 2 /hr) and PBS f (3.6gCH 4 /m 2 /hr), which may be due to their low organic content and void index, respectively. Activated membranes with high load capacity did not seem to have an influence on the methane oxidation process: MBP coupled with 220g/m 2 and 360g/m 2 membranes gave maximum MOR of 16.5gCH 4 /m 2 /hr and 17.4gCH 4 /m 2 /hr, respectively. Activated carbon membranes proved to be very effective on H 2 S adsorption. Furthermore, carbonyl sulphide, ethyl mercaptan and isopropyl mercaptan seemed to be easily absorbed by the filling materials. Copyright © 2017. Published by Elsevier B.V.

  3. Quantitative analysis of free and bonded forms of volatile sulfur compouds in wine. Basic methodologies and evidences showing the existence of reversible cation-complexed forms.

    Science.gov (United States)

    Franco-Luesma, Ernesto; Ferreira, Vicente

    2014-09-12

    This paper examines first some basic aspects critical to the analysis of Volatile Sulfur Compounds (VSCs), such as the analytical characteristics of the GC-pFPD system and the stability of the different standard solutions required for a proper calibration. Following, a direct static headspace analytical method for the determination of exclusively free forms of VSCs has been developed. Method repeatability is better than 4%, detection limits for main analytes are below 0.5μgL(-1), and the method dynamic linear range (r(2)>0.99) is expanded by controlling the split ratio in the chromatographic inlet to cover the natural range of occurrence of these compounds in wines. The method gives reliable estimates of headspace concentrations but, as expected, suffers from strong matrix effects with recoveries ranging from 0 to 100% or from 60 to 100 in the cases of H2S and the other mercaptans, respectively. This demonstrates the existence of strong interactions of these compounds with different matrix components. The complexing ability of Cu(2+) and to a lower extent Fe(2+) and Zn(2+) has been experimentally checked. A previously developed method in which the wine is strongly diluted with brine and the volatiles are preconcentrated by HS-SPME, was found to give a reliable estimation of the total amount (free+complexed) of mercaptans, demonstrating that metal-mercaptan complexes are reversible. The comparative analysis of different wines by the two procedures reveals that in normal wines H2S and methanethiol can be complexed at levels above 99%, with averages around 97% for H2S and 75% for methanethiol, while thioethers such as dimethyl sulfide (DMS) are not complexed. Overall, the proposed strategy may be generalized to understand problems caused by VSCs in different matrices. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Linear dimensional changes in plaster die models using different elastomeric materials

    Directory of Open Access Journals (Sweden)

    Jefferson Ricardo Pereira

    2010-09-01

    Full Text Available Dental impression is an important step in the preparation of prostheses since it provides the reproduction of anatomic and surface details of teeth and adjacent structures. The objective of this study was to evaluate the linear dimensional alterations in gypsum dies obtained with different elastomeric materials, using a resin coping impression technique with individual shells. A master cast made of stainless steel with fixed prosthesis characteristics with two prepared abutment teeth was used to obtain the impressions. References points (A, B, C, D, E and F were recorded on the occlusal and buccal surfaces of abutments to register the distances. The impressions were obtained using the following materials: polyether, mercaptan-polysulfide, addition silicone, and condensation silicone. The transfer impressions were made with custom trays and an irreversible hydrocolloid material and were poured with type IV gypsum. The distances between identified points in gypsum dies were measured using an optical microscope and the results were statistically analyzed by ANOVA (p < 0.05 and Tukey's test. The mean of the distances were registered as follows: addition silicone (AB = 13.6 µm, CD=15.0 µm, EF = 14.6 µm, GH=15.2 µm, mercaptan-polysulfide (AB = 36.0 µm, CD = 36.0 µm, EF = 39.6 µm, GH = 40.6 µm, polyether (AB = 35.2 µm, CD = 35.6 µm, EF = 39.4 µm, GH = 41.4 µm and condensation silicone (AB = 69.2 µm, CD = 71.0 µm, EF = 80.6 µm, GH = 81.2 µm. All of the measurements found in gypsum dies were compared to those of a master cast. The results demonstrated that the addition silicone provides the best stability of the compounds tested, followed by polyether, polysulfide and condensation silicone. No statistical differences were obtained between polyether and mercaptan-polysulfide materials.

  5. Impact of Natural Gas Exploitation Plant on the Environment

    International Nuclear Information System (INIS)

    Cackovic, M.; Marovic, G.; Pehnec, G.; Sencar, J.; Vadic, V.

    2013-01-01

    Exploitation of natural gas at the gas field Molve has been provided more than 20 years. Natural gas and gas condensate have been extracted from 34 bores in Podravina on an area wider than 200 km 2 . The gas is then transported to the central gas station CPS Molve using a closed collection and transportation system. In addition to hydrocarbons, natural gas contains many other substances such as CO 2 , H 2 S, mercaptanes, Hg, and water which have to be removed at the Molve station by different technological processes. This paper presents the results of H 2 S, mercaptanes and SO 2 monitoring at measuring sites MOLVE-9, MOLVE-10, and MOLVE-CGS in the area of influence of a central natural gas station Molve in 2011. Measurements were carried out one month in the summer and one month in the autumn. H 2 S levels exceeded the Croatian limit values (LV) at all three measuring sites, while the mercaptan levels exceeded the Croatian LV at MOLVE-10 in the autumn. The obtained results showed that the levels of SO 2 mass concentrations were below LV. During the same measuring periods, at the same measuring sites, radiation was measured using ALARA dosimeters (expressed here as mean daily dose rates). Absorbed dose measurements were calculated on yearly base. At MOLVE-9 yearly equivalent dose was 0.680 ± 0.064 mSv, at MOLVE-10 0.855 ± 0.079 mSv and at MOLVE-CGS 0.772 ± 0.067 mSv. The measurements also showed that the refining processes at the gas station did not increase radioactivity in the environment. Observed variations were within the normal fluctuations.(author)

  6. Health assessment for Artel Chemical Company, Formerly Fike Chemical, Incorporated, City of Nitro, Putnam and Kanawha Counties, West Virginia, Region 3. CERCLIS No. WVD047989207. Preliminary report

    Energy Technology Data Exchange (ETDEWEB)

    1988-09-23

    The Artel Chemical Company site, formerly known as Fike Chemical Inc., manufactured specialty chemicals. There are many compounds on-site which are known to represent imminent and significant public health threats. Several compounds/contaminants of the most immediate concern are methyl mercaptan, bromine, sodium, ethyl and sodium fluoroacetate, and cyanide compounds. ATSDR has concluded that this site is of urgent public health concern because of the risk to human health resulting from the potential exposure to hazardous substances at concentrations that may result in acute health effects or death.

  7. S8 -Mediated Cyclization of 2-Aminophenols/thiophenols with Arylmethyl Chloride: Approach to Benzoxazoles and Benzothiazoles.

    Science.gov (United States)

    Gan, Haifeng; Miao, Dazhuang; Pan, Qiang; Hu, Renhe; Li, Xiaotong; Han, Shiqing

    2016-06-21

    A metal-free approach to benzazoles from arylmethyl chlorides and 2-mercaptan/2-hydroxyanilines using elemental sulfur as a traceless oxidizing agent has been developed. The reactions proceeded in good to excellent yields, exhibiting good functional groups tolerance and gram-scale ability. A key mechanistic investigation indicated that the key intermediate trisulfide 6, which was characterized by NMR, HRMS and crystal X-ray crystallography, was separated in the reaction prior to the formation of the product. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Method of generating chemiluminescent light

    Science.gov (United States)

    Spurlin, S.R.; Yeung, E.S.

    1986-03-11

    A method of chemiluminescently determining a sulfide which is either hydrogen sulfide or methyl mercaptan by reacting the sulfide with chlorine dioxide at low pressure and under conditions which allow a longer reaction time in emission of a single photon for every two sulfide containing species, and thereafter, chemiluminescently detecting and determining the sulfide. The invention also relates not only to the detection method, but the novel chemical reaction that generates chemiluminescent light and a specifically designed chemiluminescence detection cell for the reaction. 4 figs.

  9. Toxic Hazards in Aviation.

    Science.gov (United States)

    1981-04-01

    contenir un rat ou deux Souria. L’extriaitis libre do Is lame eat reliia par un fil A IPaxe d’un petit moteur synchrons dont la barnes sont relides & un...evident in Table 2. TABLE 2 SOME SELECTED MILITARY SPECIFICATIONS FOR JP-5 1 Distillation temp °C Initial B.P. --- 10% recovery 205 End point, max... temp 290 Aromatics, vol %, max 25 Olefins, vol %, max 5 Sulfur, total wt %, max 0.4 Sulfur, mercaptan, wt % .001 Hydrogen content, wt % 13.5 Freezing

  10. Dietary composition affects odour emissions from meat chickens

    Directory of Open Access Journals (Sweden)

    Nishchal K. Sharma

    2015-03-01

    Full Text Available Abatement of odour emissions has become an important consideration to agricultural industries, including poultry production. The link between diet and odour emissions was studied in two experiments using Ross 308 male meat chickens reared in specially designed chambers in a climate controlled room. In the first experiment, two treatments were compared using three replicates of two birds per chamber. Two wheat-soy based treatment diets were formulated with or without canola seed, an ingredient rich in sulfur amino acids. Treatment 1 (T1 had 13.39 MJ/kg ME (as fed and used 60 g/kg canola seed without corn while Treatment 2 (T2 contained 12.90 MJ/kg ME (as fed and used 150 g/kg corn without canola seed. In the second experiment, birds were assigned to three dietary treatments of five replicates with five birds per replicate (chamber. The basal starter, grower and finisher diets in the control group (SBM group contained soybean meal in the range of 227–291 g/kg (as fed as the main protein source. The other treatments (CM and MBM groups contained either high levels of canola meal (174–190 g/kg or meat meal (74–110 g/kg at the expense of soybean meal. In both experiments, diets were isocaloric, isonitrogenous and contained similar digestible amino acid contents as per 2007 Aviagen Ross 308 guidelines. Emissions of odour were measured using Fourier transform infrared (FTIR spectroscopy. In both experiments, major odorous compounds detected included 2,3-butanedione (diacetyl, 2-butanone, dimethyl disulfide, methyl mercaptan, ethyl mercaptan, 2-butanol, 3-methyl-butanal, phenol and m-cresol. In the first experiment, T1 (with canola seed produced higher concentration of methyl mercaptan (P < 0.05 and lower diacetyl (P < 0.01 than T2. In the second experiment, methyl mercaptan emission was higher in SBM group (P = 0.01 and total elemental sulfur were higher in SBM and CM groups up to day 24 (P < 0.01. Results of these experiments

  11. The application of PS printing plate with Biimidazole photosensitive initiating systems

    International Nuclear Information System (INIS)

    Li Lidong; Xu Jinqi; Gao Fang; Yang Yongyuan

    1999-01-01

    The ultraviolet photosensitive initiating system is composed of 4,4'-bis(N,N'-dimethyl-amino)benzophenone(MK), 2-chlorohexaarylbiimidazole(o-C1-HABI) and a hydrogen donor co-initiator n-dodecyl mercaptan(SH). Under the irradiation by high pressure mercury lamp, the relationship between the photo-polymerization rate of MMA and the concentration of each component of the system, including MK, o-C1-HABI and SH, was studied. The excellent results have been obtained through studying the system's application on PS lithographic printing plate

  12. Organusulfur Catalysis With Reduced Molybdenum Sulfides Containing the Mo6S8 Cluster

    Energy Technology Data Exchange (ETDEWEB)

    Paskach, Thomas Jay [Iowa State Univ., Ames, IA (United States)

    2002-08-27

    Industrial synthesis of sulfur-containing organic chemicals basically focuses on the broad categories of mercaptans (thiols), alkylsulfides (thioethers), polysulfides, and thiophenes. Of the organo-sulfur compounds produced, by far the most important in terms of quantities produced is methyl mercaptan (methanethiol or MeSH), which is produced mainly for the downstream production of methionine and methanesulfonyl chloride. Higher thiols are also used in the manufacture of rubber and plastics as polymerization regulators, chain transfer agents, or initiators. Other important organosulfur chemicals are dimethyl sulfide (DMS) and dimethyl disulfide (DMDS), both of which are used extensively for presulfiding of industrial hydroprocessing catalysts, and substituted thiophenes which are used as intermediates for production of agrochemicals, dyes, and pharmaceuticals. Thiols are produced commercially at the rate of about 104 ton/yr from hydrogen sulfide (H2S) and alcohols or olefins, using homogeneous free-radical synthesis, or heterogeneous catalysts based on solid acids or supported metal oxides and/or sulfides. Despite this large production rate, and the industrial importance of the organosulfur compounds, only limited research has been devoted to the development of new catalytic materials for their synthesis. Additionally, for most organosulfur catalytic reactions, only limited information exists about reaction mechanisms, active sites, adsorbed surface species, and especially the nature of the catalysts under reaction conditions.

  13. Quantitative analysis of sulfur forms of coal and the pyrolysis behavior of sulfur compounds; Sekitanchu no io kagobutsu no keitaibetsu gan`yuryo no teiryo to sono netsubunkai kyodo

    Energy Technology Data Exchange (ETDEWEB)

    Mae, K.; Miura, K.; Shimada, M. [Kyoto University, Kyoto (Japan). Faculty of Engineering

    1996-10-28

    As part of the studies on coal utilization basics, considerations were given on quantification of sulfur forms of coal and the pyrolysis behavior of sulfur compounds. With the temperature raising oxidation method, a thermo-balance was connected directly to a mass analyzer, and the coal temperature was raised at a rate of 5{degree}C per minute and gasified. Peak division was performed on SO2 and COS production to derive sulfur forms of coal. Using the slow-speed pyrolysis method, production rates of H2S, COS, SO2 and mercaptans were measured at a temperature raising rate of 20{degree}C per minute. Sulfur content in char was also measured. With the quick pyrolysis method, a Curie point pyrolyzer was connected directly to a gas chromatograph, by which secondary reaction is suppressed, and initial pyrolytic behavior can be tracked. All kinds of coals produce a considerable amount of SO2 in the slow-speed pyrolysis, but very little in the quick pyrolysis. Instead, H2S and mercaptans are produced. Sulfur compound producing mechanisms vary depending on the temperature raising rates. By using a parallel primary reaction model, analysis was made on reactions of H2S production based on different activation energies, such as those generated from pyrite decomposition and organic sulfur decomposition. The analytic result agreed also with that from the temperature raising oxidation method. 4 refs., 6 figs., 1 tab.

  14. Morphological study of polymethyl methacrylate microcapsules filled with self-healing agents

    Science.gov (United States)

    Ahangaran, Fatemeh; Hayaty, Mehran; Navarchian, Amir H.

    2017-03-01

    Polymethyl methacrylate (PMMA) microcapsules filled with epoxy prepolymer, 3-aminomethyl-3,5,5-trimethylcyclohexylamine, and pentaerythritol tetrakis (3-mercaptopropionate) as healing agents have been prepared separately through internal phase separation method for self-healing purposes. PMMA with two different molecular weights (M bar1 = 36,000 g/mol and M bar2 = 550,000 g/mol) were used with two types of different emulsifiers (ionic and polymeric) to prepare microcapsules. The morphology of healing agent microcapsules was investigated using field emission scanning electron microscopy (FESEM). It was found that PMMA microcapsules separately filled with epoxy and amine had core-shell morphologies with smooth surfaces. The mercaptan/PMMA particles exhibited core-shell and acorn-shape morphologies. The surface morphology of mercaptan microcapsules changed from holed to plain in different emulsion systems. The spreading coefficient (S) of phases in the prepared emulsion systems were calculated from interfacial tension (σ) and contact angle (θ) measurements. The theoretical equilibrium morphology of PMMA microcapsules was predicted according to spreading coefficient values of phases in emulsion systems. It was also found that the surface morphology of PMMA microcapsules depended strongly on the nature of the core, molecular weight of PMMA, type and concentration of emulsifier.

  15. Effect of milk on the deodorization of malodorous breath after garlic ingestion.

    Science.gov (United States)

    Hansanugrum, Areerat; Barringer, Sheryl A

    2010-08-01

    The effect of milk and milk components on the deodorization of diallyl disulfide (DADS), allyl methyl disulfide (AMDS), allyl mercaptan (AM), allyl methyl sulfide (AMS), and methyl mercaptan (MM) in the headspace of garlic as well as in the mouth- and nose-space after garlic ingestion was investigated using selected ion flow tube-mass spectrometry (SIFT-MS). Fat-free and whole milk significantly reduced the head-, mouth-, and nose-space concentrations of all volatiles. Water was the major component in milk responsible for the deodorization of volatiles. Due to its higher fat content, whole milk was more effective than fat-free milk in the deodorization of the more hydrophobic volatiles diallyl disulfide and allyl methyl disulfide. Milk was more effective than water and 10% sodium caseinate in the deodorization of allyl methyl sulfide, a persistent garlic odor, in the mouth after garlic ingestion. Addition of milk to garlic before ingestion had a higher deodorizing effect on the volatiles in the mouth than drinking milk after consuming garlic. Practical Application: Ingesting beverages or foods with high water and/or fat content such as milk may help reduce the malodorous odor in breath after garlic ingestion and mask the garlic flavor during eating. To enhance the deodorizing effect, deodorant foods should be mixed with garlic before ingestion.

  16. Omeprazole, a specific inhibitor of gastric (H+-K+)-ATPase, is a H+-activated oxidizing agent of sulfhydryl groups

    International Nuclear Information System (INIS)

    Im, W.B.; Sih, J.C.; Blakeman, D.P.; McGrath, J.P.

    1985-01-01

    Omeprazole (5-methoxy-2-[[(4-methoxy-3,5- dimethylpyridinyl)methyl]sulfinyl]-1H-benzimidazole) appeared to inhibit gastric (H + -K + )-ATPase by oxidizing its essential sulfhydryl groups, since the gastric ATPase inactivated by the drug in vivo or in vitro recovered its K+-dependent ATP hydrolyzing activity upon incubation with mercaptoethanol. Biological reducing agents like cysteine or glutathione, however, were unable to reverse the inhibitory effect of omeprazole. Moreover, acidic environments enhanced the potency of omeprazole. The chemical reactivity of omeprazole with mercaptans is also consistent with the biological action of omeprazole. The N-sulfenylated compound reacted at neutral pH with another stoichiometric amount of ethyl mercaptan to produce omeprazole sulfide quantitatively. The gastric polypeptides of 100 kilodaltons representing (H + -K + )-ATPase in the rat gastric mucosa or isolated hog gastric membranes were covalently labeled with [ 14 C]omeprazole. The radioactive label bound to the ATPase, however, could not be displaced by mercaptoethanol under the identical conditions where the ATPase activity was fully restored. These observations suggest that the essential sulfhydryl groups which reacted with omeprazole did not form a stable covalent bond with the drug, but rather that they further reacted with adjacent sulfhydryl groups to form disulfides which could be reduced by mercaptoethanol

  17. Omeprazole, a specific inhibitor of gastric (H/sup +/-K/sup +/)-ATPase, is a H/sup +/-activated oxidizing agent of sulfhydryl groups

    Energy Technology Data Exchange (ETDEWEB)

    Im, W.B.; Sih, J.C.; Blakeman, D.P.; McGrath, J.P.

    1985-04-25

    Omeprazole (5-methoxy-2-(((4-methoxy-3,5- dimethylpyridinyl)methyl)sulfinyl)-1H-benzimidazole) appeared to inhibit gastric (H/sup +/-K/sup +/)-ATPase by oxidizing its essential sulfhydryl groups, since the gastric ATPase inactivated by the drug in vivo or in vitro recovered its K+-dependent ATP hydrolyzing activity upon incubation with mercaptoethanol. Biological reducing agents like cysteine or glutathione, however, were unable to reverse the inhibitory effect of omeprazole. Moreover, acidic environments enhanced the potency of omeprazole. The chemical reactivity of omeprazole with mercaptans is also consistent with the biological action of omeprazole. The N-sulfenylated compound reacted at neutral pH with another stoichiometric amount of ethyl mercaptan to produce omeprazole sulfide quantitatively. The gastric polypeptides of 100 kilodaltons representing (H/sup +/-K/sup +/)-ATPase in the rat gastric mucosa or isolated hog gastric membranes were covalently labeled with (/sup 14/C)omeprazole. The radioactive label bound to the ATPase, however, could not be displaced by mercaptoethanol under the identical conditions where the ATPase activity was fully restored. These observations suggest that the essential sulfhydryl groups which reacted with omeprazole did not form a stable covalent bond with the drug, but rather that they further reacted with adjacent sulfhydryl groups to form disulfides which could be reduced by mercaptoethanol.

  18. Inhibitory Effect ofEnterococcus faeciumWB2000 on Volatile Sulfur Compound Production byPorphyromonas gingivalis.

    Science.gov (United States)

    Suzuki, Nao; Higuchi, Takuya; Nakajima, Masato; Fujimoto, Akie; Morita, Hiromitsu; Yoneda, Masahiro; Hanioka, Takashi; Hirofuji, Takao

    2016-01-01

    Volatile sulfur compounds (VSCs) produced by oral anaerobes are the major compounds responsible for oral malodor. Enterococcus faecium WB2000 is recognized as an antiplaque probiotic bacterium. In this study, the effect of E. faecium WB2000 on VSC production by Porphyromonas gingivalis was evaluated, and the mechanism of inhibition of oral malodor was investigated. P. gingivalis ATCC 33277 was cultured in the presence of four lactic acid bacteria, including E. faecium WB2000. Subsequently, P. gingivalis ATCC 33277, W50, W83, and two clinical isolates were cultured in the presence or absence of E. faecium WB2000, and the emission of VSCs from spent culture medium was measured by gas chromatography. The number of P. gingivalis ATCC 33277 in mixed culture with E. faecium WB2000 decreased at 6 h, and the rate of decrease was higher than that in mixed cultures with the other lactic acid bacteria. The numbers of five P. gingivalis strains decreased at similar rates in mixed culture with E. faecium WB2000. The concentration of methyl mercaptan was lower in spent culture medium from P. gingivalis and E. faecium WB2000 cultures compared with that from P. gingivalis alone. Therefore, E. faecium WB2000 may reduce oral malodor by inhibiting the growth of P. gingivalis and neutralizing methyl mercaptan.

  19. Effect of Selected Mercapto Flavor Compounds on Acrylamide Elimination in a Model System

    Directory of Open Access Journals (Sweden)

    Zhiyong Xiong

    2017-05-01

    Full Text Available The effect of four mercapto flavor compounds (1,2-ethanedithiol, 1-butanethiol, 2-methyl-3-furanthiol, and 2-furanmethanethiol on acrylamide elimination were investigated in model systems. The obtained results showed that mercaptans assayed were effective in elimination arylamide in a model system. Their reactivities for decreasing acrylamide content depended on mercaptan’s molecular structure and acrylamide disappearance decreased in the following order: 1,2-ethanedithiol > 2-methyl-3-furanthiol > 1-butanethiol > 2-furanmethanethiol. Mercaptans were added to acrylamide to produce the corresponding 3-(alkylthio propionamides. This reaction was irreversible and only trace amounts of acrylamide were formed by thermal heating of 3-(alkylthio propanamide. Although a large amount disappeared, only part of the acrylamide conversed into 3-(alkylthio propionamides. All of these results constitute a fundamental proof of the complexity of the reactions involved in the removal of free acrylamide in foods. This implies mercapto flavor/aroma may directly or indirectly reduce the level of acrylamide in food processing. This study could be regarded as a pioneer contribution on acrylamide elimination in a model system by the addition of mercapto flavor compounds.

  20. Infrared Spectra and Band Strengths of CH3SH, an Interstellar Molecule

    Science.gov (United States)

    Hudson, R. L.

    2016-01-01

    Three solid phases of CH3SH (methanethiol or methyl mercaptan) have been prepared and their mid-infrared spectra recorded at 10-110 degrees Kelvin, with an emphasis on the 17-100 degrees Kelvin region. Refractive indices have been measured at two temperatures and used to estimate ice densities and infrared band strengths. Vapor pressures for the two crystalline phases of CH3SH at 110 degrees Kelvin are estimated. The behavior of amorphous CH3SH on warming is presented and discussed in terms of Ostwald's step rule. Comparisons to CH3OH under similar conditions are made, and some inconsistencies and ambiguities in the CH3SH literature are examined and corrected.

  1. Self-healing epoxy composite with heat-resistant healant.

    Science.gov (United States)

    Yuan, Yan Chao; Ye, Xiao Ji; Rong, Min Zhi; Zhang, Ming Qiu; Yang, Gui Cheng; Zhao, Jian Qing

    2011-11-01

    To provide self-healing epoxy composite with adequate heat resistance for high-performance application, we developed a novel microencapsulated epoxy/mercaptan healing agent. The key measure lies in usage of diglycidyl ether of bisphenol A (EPON 828) as the polymerizable component and 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30) as the catalyst. Because of the higher thermal stability of EPON 828 and lower volatility of DMP-30, the healing agent and the self-healing composite not only survive high-temperature curing and thermal exposure, but also offer satisfactory capability of autonomous properties restoration, as characterized by both fracture mechanics and fatigue tests. Especially when the operation temperature is not higher than 200 °C, the performance of the healing system is nearly independent of thermal history.

  2. The preparation and physical properties of polysulfide-based elastomers through one-pot thiol-ene click reaction

    Directory of Open Access Journals (Sweden)

    Y. W. Quan

    2013-07-01

    Full Text Available In this paper, polysulfide-based elastomers were successfully prepared through a simple one-pot thiol-ene click reaction of the liquid polysulfide oligomer with bisphenol-A diacrylate resin. Real-time Fourier transform infrared spectroscopy (FTIR analysis showed that the molecular weight of the liquid polysulfide oligomer had no effect on mercaptan functional group conversion. The obtained elastomers continued to keep low temperature flexibility of polysulfide except Elastomer-LP3, which was due to higher content of bisphenol-A structure. All the samples had a tensile strength of over 0.7 MPa, which was comparable to that of polysulfide polymer cured by metal oxide. Moreover, the samples exhibited higher thermal stability than metal oxide cured polysulfide. This vulcanization methodology will provide a fast, efficient, and environmentally friendly approach (without metal oxides and plasticizers for preparing polysulfide elastomers.

  3. Sensory and chemical drivers of wine minerality aroma: An application to Chablis wines.

    Science.gov (United States)

    Rodrigues, Heber; Sáenz-Navajas, María-Pilar; Franco-Luesma, Ernesto; Valentin, Dominique; Fernández-Zurbano, Purificación; Ferreira, Vicente; De La Fuente Blanco, Arancha; Ballester, Jordi

    2017-09-01

    The goal of this work was to evaluate the effect of vineyard position on the minerality of wines and to establish relationships between minerality scores, sensory descriptors and chemical composition. Sensory analyses included minerality rating and free description performed by wine professionals under two conditions: orthonasal olfaction alone and global tasting. Chemical characterization included analysis of major and minor volatile compounds, volatile sulphur compounds, mercaptans, metals, anions and cations. Results showed a significant effect of the river bank on wine minerality scores only in the orthonasal olfaction condition, samples from the left being more mineral than those from the right bank. Methanethiol, involved in shellfish aroma, was significantly higher in wines from the left (more mineral) than from the right bank. Contrary, copper levels, related to lower levels of free MeSH, and norisoprenoids, responsible for white fruit and floral aromas, were higher in wines from the right bank (less mineral). Copyright © 2017. Published by Elsevier Ltd.

  4. Galloylated proanthocyanidins from shea (Vitellaria paradoxa) meal have potent anthelmintic activity against Ascaris suum.

    Science.gov (United States)

    Ramsay, A; Williams, A R; Thamsborg, S M; Mueller-Harvey, I

    2016-02-01

    Proanthocyanidins (PA) from shea (Vitellaria paradoxa) meal were investigated by thiolytic degradation with benzyl mercaptan and the reaction products were analysed by high performance liquid chromatography-mass spectrometry. These PA were galloylated (≈40%), contained only B-type linkages and had a high proportion of prodelphinidins (>70%). The mean degree of polymerisation was 8 (i.e. average molecular size was 2384Da) and epigallocatechin gallate (EGCg) was the major flavan-3-ol subunit in PA. Shea meal also proved to be a potentially valuable source for extracting free flavan-3-ol-O-gallates, especially EGCg (575mg/kg meal), which is known for its health and anti-parasitic benefits. Proanthocyanidins were isolated and tested for bioactivity against Ascaris suum, which is an important parasite of pigs. Migration and motility tests revealed that these PA have potent activity against this parasitic nematode. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

  5. Sodium Hydroxide Enhances Extractability and Analysis of Proanthocyanidins in Ensiled Sainfoin (Onobrychis viciifolia).

    Science.gov (United States)

    Ramsay, Aina; Drake, Chris; Grosse Brinkhaus, Anja; Girard, Marion; Copani, Giuseppe; Dohme-Meier, Frigga; Bee, Giuseppe; Niderkorn, Vincent; Mueller-Harvey, Irene

    2015-11-04

    Little information exists on the effects of ensiling on condensed tannins or proanthocyanidins. The acetone-butanol-HCl assay is suitable for measuring proanthocyanidin contents in a wide range of samples, silages included, but provides limited information on proanthocyanidin composition, which is of interest for deciphering the relationships between tannins and their bioactivities in terms of animal nutrition or health. Degradation with benzyl mercaptan (thiolysis) provides information on proanthocyanidin composition, but proanthocyanidins in several sainfoin silages have proved resistant to thiolysis. We now report that a pretreatment step with sodium hydroxide prior to thiolysis was needed to enable their analysis. This alkaline treatment increased their extractability from ensiled sainfoin and facilitated especially the release of larger proanthocyanidins. Ensiling reduced assayable proanthocyanidins by 29%, but the composition of the remaining proanthocyanidins in silage resembled that of the fresh plants.

  6. Lossless synthesis of graphene nanosheets decorated with tiny cadmium sulfide quantum dots with excellent nonlinear optical properties

    Science.gov (United States)

    Feng, Miao; Sun, Ruiqing; Zhan, Hongbing; Chen, Yu

    2010-02-01

    The implantation and growth of metal nanoparticles on graphene nanosheets (GNS) leads directly to severe damage to the regular structure of the graphene sheets, which disrupts the extended π conjugation, resulting in an impaired device performance. In this paper, we describe a facile approach for achieving the lossless formation of graphene composite decorated with tiny cadmium sulfide quantum dots (QDs) with excellent nonlinear optical properties by using benzyl mercaptan (BM) as the interlinker. The mercapto substituent of BM binds to the CdS QDs during their nucleation and growth process, and then the phenyl comes into contact with the GNS via the π-π stacking interaction. Using this strategy, CdS QDs with an average diameter of 3 nm are uniformly dispersed over the surface of graphene, and the resulting QD-graphene composite exhibits excellent optical limiting properties, mainly contributed by nonlinear scattering and nonlinear absorption, upon both 532 and 1064 nm excitations, in the nanosecond laser pulse regime.

  7. Inhibitory effect of Lactobacillus reuteri on periodontopathic and cariogenic bacteria.

    Science.gov (United States)

    Kang, Mi-Sun; Oh, Jong-Suk; Lee, Hyun-Chul; Lim, Hoi-Soon; Lee, Seok-Woo; Yang, Kyu-Ho; Choi, Nam-Ki; Kim, Seon-Mi

    2011-04-01

    The interaction between Lactobacillus reuteri, a probiotic bacterium, and oral pathogenic bacteria have not been studied adequately. This study examined the effects of L. reuteri on the proliferation of periodontopathic bacteria including Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, Porphyromonas gingivalis, and Tannerella forsythia, and on the formation of Streptococcus mutans biofilms. Human-derived L. reuteri strains (KCTC 3594 and KCTC 3678) and rat-derived L. reuteri KCTC 3679 were used. All strains exhibited significant inhibitory effects on the growth of periodontopathic bacteria and the formation of S. mutans biofilms. These antibacterial activities of L. reuteri were attributed to the production of organic acids, hydrogen peroxide, and a bacteriocin-like compound. Reuterin, an antimicrobial factor, was produced only by L. reuteri KCTC 3594. In addition, L. reuteri inhibited the production of methyl mercaptan by F. nucleatum and P. gingivalis. Overall, these results suggest that L. reuteri may be useful as a probiotic agent for improving oral health.

  8. Lossless synthesis of graphene nanosheets decorated with tiny cadmium sulfide quantum dots with excellent nonlinear optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Feng Miao; Zhan Hongbing [College of Materials Science and Engineering, Fuzhou University, 2 Xueyuan Road, Fuzhou 350108 (China); Sun Ruiqing [College of Chemistry and Chemical Engineering, Fuzhou University, 2 Xueyuan Road, Fuzhou 350108 (China); Chen Yu, E-mail: hbzhan@fzu.edu.cn, E-mail: chentangyu@yahoo.com [Laboratory for Advanced Materials, Department of Chemistry, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237 (China)

    2010-02-19

    The implantation and growth of metal nanoparticles on graphene nanosheets (GNS) leads directly to severe damage to the regular structure of the graphene sheets, which disrupts the extended {pi} conjugation, resulting in an impaired device performance. In this paper, we describe a facile approach for achieving the lossless formation of graphene composite decorated with tiny cadmium sulfide quantum dots (QDs) with excellent nonlinear optical properties by using benzyl mercaptan (BM) as the interlinker. The mercapto substituent of BM binds to the CdS QDs during their nucleation and growth process, and then the phenyl comes into contact with the GNS via the {pi}-{pi} stacking interaction. Using this strategy, CdS QDs with an average diameter of 3 nm are uniformly dispersed over the surface of graphene, and the resulting QD-graphene composite exhibits excellent optical limiting properties, mainly contributed by nonlinear scattering and nonlinear absorption, upon both 532 and 1064 nm excitations, in the nanosecond laser pulse regime.

  9. Rapid labeling of amino acid neurotransmitters with a fluorescent thiol in the presence of o-phthalaldehyde.

    Science.gov (United States)

    Maddukuri, Naveen; Zhang, Qiyang; Zhang, Ning; Gong, Maojun

    2017-02-01

    LIF detection often requires labeling of analytes with fluorophores; and fast fluorescent derivatization is valuable for high-throughput analysis with flow-gated CE. Here, we report a fast fluorescein-labeling scheme for amino acid neurotransmitters, which were then rapidly separated and detected in flow-gated CE. This scheme was based on the reaction between primary amines and o-phthalaldehyde in the presence of a fluorescent thiol, 2-((5-fluoresceinyl)aminocarbonyl)ethyl mercaptan (FACE-SH). The short reaction time (neurotransmitters by coupling in vitro microdialysis with online derivatization and flow-gated CE. It is also anticipated that this fluorophore tagging scheme would be valuable for on-chip labeling of proteins retained on support in SPE. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Syntheses of some Bunte's salts, isothiourea derivatives and thioethers, potential radioprotective agents. Part 40

    International Nuclear Information System (INIS)

    Tulecki, J.; Kalinowska Torz, J.; Musial, E.; Nacewicz-Anjedani, H.; Senczuk, L.; Skwarski, D.; Sobolewski, H.

    1977-01-01

    By reacting respective halogen-derivatives with sodium or potassium thiosulphate there were obtained sodium or potassium salts of S-thiosulphates of 1-ureidocarbonyl-1-butyl, 3,4-dihydroxyphenacyl, carbophenoxymethyl, 2-hydroxyphenacyl, /N-(4-iodophenyl) carbamyl/methyl, /N-(4-iodophenyl) carbamyl/ethyl, /N-(2-iodophenyl) carbamyl/-methyl, /N-(2-iodophenyl) carbamyl/ethyl, /N-(6-carbomethoxybenzothiazolyl-2)-carbamyl/methyl, (2,4-dihydroxy-6-methylpyrimidyl-5)-methyl and (2,4-dihydroxypyrimidyl-5)-methyl. Reactions of thiourea with respective halogen-derivatives yielded hydrochlorides of 1-methyl-02-amidinothiomethylbenzimidazole, 1-ethyl-2-amidinothiomethylbenzimidazole, S-/N-(2-iodophenyl) carbamylethyl/ isothiourea, 5-amidinothiomethyl-6-methyl-2,4-dihydroxypyrimide and 5-amidinothiomethyl-2,4-dihydroxypyrimidine. Reactions of 4-chloroquinoline N-oxide with respective mercaptanes afforded thioether derivatives of quinoline N-oxide: 4-(p-chlorophenylthio)-4-(t-butylthio)-, 4-(3-naphtylthio)-, 4-(3-naphtylaminoacetylthio), 4-(benzimidazolythio)-, 4-(benzothiazolylthio) - and 4-benzoxalylthio. (author)

  11. 5-Substituted-benzylsulfanyl-thiophene-2-sulfonamides with effective carbonic anhydrase inhibitory activity: Solution and crystallographic investigations.

    Science.gov (United States)

    Ivanova, Jekaterīna; Balode, Agnese; Žalubovskis, Raivis; Leitans, Janis; Kazaks, Andris; Vullo, Daniela; Tars, Kaspars; Supuran, Claudiu T

    2017-02-01

    A series of 5-substituted-benzylsulfanyl-thiophene-2-sulfonamides was prepared by reacting 5-bromo-thiophene-2-sulfonamide with 5-substituted-benzyl mercaptans. The new compounds were investigated as carbonic anhydrase (CA, EC 4.2.1.1) inhibitors. The cytosolic human (h) isoforms hCA I was poorly inhibited by the new sulfonamides (K I s in the range of 683-4250nM), whereas hCA II, and the transmembrane, tumor associated isoforms hCA IX and XII were effectively inhibited in the subnanomolar-nanomolar range. A high resolution X-ray crystal structure of the adduct of hCA II with one of the new sulfonamides allowed us to rationalize the excellent inhibitory activity of these heterocyclic sulfonamides. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Exploration of hydrogen odorants for fuel cell vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Imamura, Daichi; Akai, Motoaki; Watanabe, Shogo [Japan Automobile Research Institute, 2530 Karima, Tsukuba, Ibaraki 305-0822 (Japan)

    2005-12-01

    The suitability of sulfur compounds (e.g., mercaptan and sulfide) and various sulfur-free smelling compounds for hydrogen odorants were evaluated. The influence of each smelling compound on fuel cell performance was evaluated through the measurement of I-V curves and voltage decline under constant current density, and their condensation properties under high-pressure condition were evaluated by measuring their vapor pressures. The results indicated that all the sulfur compounds evaluated in this study were not suitable as hydrogen odorants since their addition to the hydrogen caused serious degradation of fuel cell performance. Among the sulfur-free compounds, however, some oxygen-containing compounds (2,3-butanedione, ethyl isobutyrate and ethyl sugar lactone) and an unsaturated hydrocarbon (5-ethylidene-2-norbornene) proved to be promising candidates since their adverse effects on the fuel cell performance were minimal and their vapor pressures were adequate. (author)

  13. Exploration of hydrogen odorants for fuel cell vehicles

    Science.gov (United States)

    Imamura, Daichi; Akai, Motoaki; Watanabe, Shogo

    The suitability of sulfur compounds (e.g., mercaptan and sulfide) and various sulfur-free smelling compounds for hydrogen odorants were evaluated. The influence of each smelling compound on fuel cell performance was evaluated through the measurement of I- V curves and voltage decline under constant current density, and their condensation properties under high-pressure condition were evaluated by measuring their vapor pressures. The results indicated that all the sulfur compounds evaluated in this study were not suitable as hydrogen odorants since their addition to the hydrogen caused serious degradation of fuel cell performance. Among the sulfur-free compounds, however, some oxygen-containing compounds (2,3-butanedione, ethyl isobutyrate and ethyl sugar lactone) and an unsaturated hydrocarbon (5-ethylidene-2-norbornene) proved to be promising candidates since their adverse effects on the fuel cell performance were minimal and their vapor pressures were adequate.

  14. Association models for petroleum applications

    DEFF Research Database (Denmark)

    Kontogeorgis, Georgios

    2013-01-01

    Thermodynamics plays an important role in many applications in the petroleum industry, both upstream and downstream, ranging from flow assurance, (enhanced) oil recovery and control of chemicals to meet production and environmental regulations. There are many different applications in the oil & gas...... industry, thus thermodynamic data (phase behaviour, densities, speed of sound, etc) are needed to study a very diverse range of compounds in addition to the petroleum ones (CO2, H2S, water, alcohols, glycols, mercaptans, mercury, asphaltenes, waxes, polymers, electrolytes, biofuels, etc) within a very...... extensive range of conditions, up to very high pressures. Actually, the petroleum industry was one of the first industrial sectors which used extensively thermodynamic models and even contributed to the development of several of the most popular and still widely used approaches. While traditional...

  15. Pengaruh Cara Aplikasi Pasta Gigi Herbal terhadap Produksi Volatile Sulfur Compound

    Directory of Open Access Journals (Sweden)

    Suryono Suryono

    2015-12-01

    Full Text Available Volatile Sulfur Compound (VSC merupakan komponen gas yang dihasilkan oleh bakteri dalam rongga mulut, terdiri dari Hidrogen sulfide, Methyl Mercaptan dan Dimethyl Sulfide. Ketiga komponen gas tersebut sering digunakan sebagai indikator untuk menilai status bau mulut seseorang. Pasta gigi berbasis herbal telah dilaporkan pada penelitian sebelumnya mampu menghambat pertumbuhan kuman penyebab penyakit periodontal. Bakteri plak dalam rongga mulut dapat dikurangi melalui cara gosok gigi dan/atau penggunaan material antiseptik. Dua kelompok subjek terpilih diberikan perlakuan dengan menggunakan pasta gigi herbal dengan cara yang berbeda, kelompok pertama dengan cara menggosok gigi dengan pasta gigi herbal sesuai dengan cara yang sudah biasa mereka lakukan dan kelompok ke-2 diberikan perlakuan dengan cara mengoleskan pasta herbal di daerah molar kiri dan kanan rahang atas. Pengambilan sampel nafas dilakukan sebelum perlakuan, 5 menit dan 2 jam paska menggosok gigi atau mengoles pasta herbal. Hasil pengamatan menunjukkan bahwa penggunaan pasta gigi herbal dengan cara sikat gigi maupun pengolesan memiliki pola yang sama pada masing-masing komponen gas sulfur yaitu peningkatan pada lima menit paska aplikasi kemudian menurun pada 2 jam paska aplikasi. Pasta gigi herbal yang diaplikasikan dengan cara gosok gigi maupun dengan cara pengolesan mempengaruhi kadar VSC yaitu yaitu menurunkan kadar Hydrogen sulfide, relatif stabil kadar methyl mercaptan dan terjadi peningkatan kadar dimethyl sulfide. Pasta gigi berbasis herbal dapat digunakan dengan cara sikat gigi maupun pengolesan untuk menurunkan kadar gas VSC, khususnya Hydrogen sulfide pada subjek normal. Effect of Herbal Toothpaste Application Method on Production of Volatile Sulfur Compound. Volatile sulfur compound (VSC is a component of the gas produced by bacteria in the oral cavity, consisting of hydrogen sulfide,methyl mercaptan and dimethyl sulfide. This gas is often used as an indicator to assess the

  16. Biogas utilization

    Energy Technology Data Exchange (ETDEWEB)

    Moser, M.A. [Resource Conservation Management, Inc., Berkeley, CA (United States)

    1996-01-01

    Options for successfully using biogas depend on project scale. Almost all biogas from anaerobic digesters must first go through a gas handling system that pressurizes, meters, and filters the biogas. Additional treatment, including hydrogen sulfide-mercaptan scrubbing, gas drying, and carbon dioxide removal may be necessary for specialized uses, but these are complex and expensive processes. Thus, they can be justified only for large-scale projects that require high-quality biogas. Small-scale projects (less than 65 cfm) generally use biogas (as produced) as a boiler fuel or for fueling internal combustion engine-generators to produce electricity. If engines or boilers are selected properly, there should be no need to remove hydrogen sulfide. Small-scale combustion turbines, steam turbines, and fuel cells are not used because of their technical complexity and high capital cost. Biogas cleanup to pipeline or transportation fuel specifications is very costly, and energy economics preclude this level of treatment.

  17. Protection of aliphatic alcohols by thiols

    International Nuclear Information System (INIS)

    Nanobashivili, E.M.; Chirakadze, G.G.; Panchvidze, M.V.; Gvilava, S.E.; Khidesheli, G.I.

    1973-01-01

    Study was made of methyl, ethyl, propyl, butyl and penthyl alcohols. The aqueous solutions of the alcohols were X-irradiated. Results are presented of the action of high-energy particles on the solutions of ethyl, propyl and butyl alcohols in the presence and absence of the minor amounts of ethanthiol. Protective effect of the -SH group was established. Addition of 1.10 -6 mol/1 of ethanthiol to butyl alcohol protects it completely against radiation conversions up to a dose of 8.10 19 eV/ml. Consideration is given to the effect of thioalcohol additives on the formation of some products of alcohol radiation oxidation. Introduction of mercaptans to the system or that of the -SH group to the organic compound molecule enhances its radiation resistance [ru

  18. Odor composition analysis and odor indicator selection during sewage sludge composting

    Science.gov (United States)

    Zhu, Yan-li; Zheng, Guo-di; Gao, Ding; Chen, Tong-bin; Wu, Fang-kun; Niu, Ming-jie; Zou, Ke-hua

    2016-01-01

    ABSTRACT On the basis of total temperature increase, normal dehydration, and maturity, the odor compositions of surface and internal piles in a well-run sewage sludge compost plant were analyzed using gas chromatography–mass spectrometry with a liquid nitrogen cooling system and a portable odor detector. Approximately 80 types of substances were detected, including 2 volatile inorganic compounds, 4 sulfur organic compounds, 16 benzenes, 27 alkanes, 15 alkenes, and 19 halogenated compounds. Most pollutants were mainly produced in the mesophilic and pre-thermophilic periods. The sulfur volatile organic compounds contributed significantly to odor and should be controlled primarily. Treatment strategies should be based on the properties of sulfur organic compounds. Hydrogen sulfide, methyl mercaptan, dimethyl disulfide, dimethyl sulfide, ammonia, and carbon disulfide were selected as core indicators. Ammonia, hydrogen sulfide, carbon disulfide, dimethyl disulfide, methyl mercaptan, dimethylbenzene, phenylpropane, and isopentane were designated as concentration indicators. Benzene, m-xylene, p-xylene, dimethylbenzene, dichloromethane, toluene, chlorobenzene, trichloromethane, carbon tetrachloride, and ethylbenzene were selected as health indicators. According to the principle of odor pollution indicator selection, dimethyl disulfide was selected as an odor pollution indicator of sewage sludge composting. Monitoring dimethyl disulfide provides a highly scientific method for modeling and evaluating odor pollution from sewage sludge composting facilities. Implications: Composting is one of the most important methods for sewage sludge treatment and improving the low organic matter content of many agricultural soils. However, odors are inevitably produced during the composting process. Understanding the production and emission patterns of odors is important for odor control and treatment. Core indicators, concentration indicators, and health indicators provide an index

  19. Influence of Central Wastewater Treatment Plant on the Environment

    International Nuclear Information System (INIS)

    Cackovic, M.; Marovic, G.; Pehnec, G.; Sencar, J.; Vadic, V.

    2013-01-01

    Project CUPOVZ (Zagreb Central Wastewater Treatment Plant) is the first concession for wastewater purification in Croatia. For the City of Zagreb this project provides compliance with EU ecological standards in the field of environmental protection and protection of waters. The construction of CUPOVZ has finished in 2007, and 'Zagrebaèke otpadne vode - Upravljanje i pogon d.o.o.' is responsible for its management, proper working and regular maintenance. The influence of the wastewater treatment plant on the environment has been monitored since the beginning of the construction in 2003. Monitoring includes radioactivity measurements and measurements of specific air pollutants. This paper presents the measuring results obtained at CUPOVZ in 2011. Measurements were carried out over four months; for thirty days in each season. Ionising radiation was measured using ALARA ED dosimeters (expressed here as mean daily absorbed dose rates). In 2011 average absorbed dose rate at CUPOVZ was 77 ± 4 nGyh -1 . Equivalent dose for population was assessed on yearly base 0.680 ± 0.064 mSv. Samples of ammonia (NH 3 ), hydrogen sulphide (H 2 S) and mercaptans (RSH) were collected by 24-hour sampling. Twenty-four-hour concentrations of ammonia ranged between 2.3 μg/m 3 and 23.0 μg/m 3 , concentrations of hydrogen sulphide were between 0 μg/m 3 and 17.8 μg/m 3 , while mercaptan concentrations ranged between 0 μg/m 3 and 0.93 μg/m 3 . H 2 S levels occasionally exceeded values set by Croatian air protection legislation.(author)

  20. Potentiometric determination of trace amounts of volatile thiols in natural gas

    International Nuclear Information System (INIS)

    Farroha, S.M.; Habboush, A.E.; Kurthab, S.Y.

    1986-01-01

    A potentiometric titration method was developed for the determination of volatile thiols in natural gas. An apparatus was devised for the quantitative absorption of volatile thiols. The measurements were performed in an ethanolic ammonium buffer solution containing a known amount of silver nitrate as supporting electrolyte. The excess silver was precipitated by a known amount of potassium iodide. The excess of iodide was back titrated potentiometrically with a standard solution of silver nitrate. The direct titration of the excess silver ions with a standard solution of potassium iodide gave a poor accuracy compared with the back titration method. Iodide selective electrode was employed as an indicator electrode and a silver-silver chloride electrode as reference electrode. The accuracy and reproducibility of the method were established by preparing several synthetic samples in which ethanthiol containing from 346.61 to 12.11 μUg mercaptan sulfur was taken as standard nitrogen as carrier gas with an optimum flow rate of 31.5 L/hr. The results obtained expressed in the form of Grans plot showed an error ranging from 0.16 to 2.39% by weight and the relative standard deviation did not exceed 2.20%. The amount of mercaptan sulfur determined in Iraqi natural gas taken directly in a cylinder from Dora refinery, Baghdad, Iraq, and after six months of storage we 23.15 Ug/L and 21.25 Ug/L respectively with a relative standard deviation not exceeded 1%. The interferences of hydrogen sulfide could be eliminated by absorption in cadimium acetate containing solution. Other sulfur containing compounds e.g. disulfides, sulfoxides which may be present in natural gas do not interfere with the analysis

  1. Development and comparative investigation of Ag-sensitive layer based SAW and QCM sensors for mercury sensing applications.

    Science.gov (United States)

    Kabir, K M Mohibul; Sabri, Ylias M; Kandjani, Ahmad Esmaielzadeh; Ippolito, Samuel J; Bhargava, Suresh K

    2016-04-21

    Piezoelectric acoustic wave devices integrated with noble metal surfaces provide exciting prospects for the direct measurement of toxic gas species such as mercury (Hg) in the atmosphere. Even though gold (Au) based acoustic wave sensors have been utilized extensively for detecting Hg, the potential of using other metal surfaces such as silver (Ag) is yet to be thoroughly studied. Here, we developed Ag sensitive layer-based surface acoustic wave (SAW) and quartz crystal microbalance (QCM) sensors and focused on their comparative analysis for Hg sensing applications with parameters such as the sensor sensitivity, selectivity, adsorption/desorption isotherm and Hg diffusion into the surface thoroughly studied. The SAW sensor was fabricated with nickel (Ni) interdigitated transducer (IDT) electrodes and a Ag thin film on the delay line of the device. In the case of the QCM sensor, the electrodes were constructed of Ag thin film and simultaneously employed as a sensitive layer. Mercury sensing experiments were conducted for a range of concentrations between 24-365 ppbv without/with the presence of some common industrial interfering gas species (i.e. ammonia, acetaldehyde, ethyl mercaptan, dimethyl disulphide, methyl ethyl ketone and humidity) at various operating temperatures in the range of 35-95 °C. The SAW sensor was found to possess up to 70 times higher response magnitudes than its QCM counterpart at 35 °C while up to 30 and 23 times higher response magnitudes were observed for the SAW sensor at elevated temperatures of 75 and 95 °C, respectively. Furthermore, the SAW sensor showed good selectivity (>89%) toward Hg(0) vapor in the presence of all the interferents tested at an operating temperature of 75 °C while the QCM sensor exhibited significant cross-sensitivity when ethyl mercaptan was introduced along with Hg(0) vapor. Overall, it is indicative that Ag-based acoustic wave sensors do have great potential for Hg sensing applications, given that right

  2. Efficient red luminescence from organic-soluble Au25 clusters by ligand structure modification

    Science.gov (United States)

    Mathew, Ammu; Varghese, Elizabeth; Choudhury, Susobhan; Pal, Samir Kumar; Pradeep, T.

    2015-08-01

    An efficient method to enhance visible luminescence in a visibly non-luminescent organic-soluble 4-(tert butyl)benzyl mercaptan (SBB)-stabilized Au25 cluster has been developed. This method relies mainly on enhancing the surface charge density on the cluster by creating an additional shell of thiolate on the cluster surface, which enhances visible luminescence. The viability of this method has been demonstrated by imparting red luminescence to various ligand-protected quantum clusters (QCs), observable to the naked eye. The bright red luminescent material derived from Au25SBB18 clusters was characterized using UV-vis and luminescence spectroscopy, TEM, SEM/EDS, XPS, TG, ESI and MALDI mass spectrometry, which collectively proposed an uncommon molecular formula of Au29SBB24S, suggested to be due to different stapler motifs protecting the Au25 core. The critical role of temperature on the emergence of luminescence in QCs has been studied. The restoration of the surface ligand shell on the Au25 cluster and subsequent physicochemical modification to the cluster were probed by various mass spectral and spectroscopic techniques. Our results provide fundamental insights into the ligand characteristics determining luminescence in QCs.An efficient method to enhance visible luminescence in a visibly non-luminescent organic-soluble 4-(tert butyl)benzyl mercaptan (SBB)-stabilized Au25 cluster has been developed. This method relies mainly on enhancing the surface charge density on the cluster by creating an additional shell of thiolate on the cluster surface, which enhances visible luminescence. The viability of this method has been demonstrated by imparting red luminescence to various ligand-protected quantum clusters (QCs), observable to the naked eye. The bright red luminescent material derived from Au25SBB18 clusters was characterized using UV-vis and luminescence spectroscopy, TEM, SEM/EDS, XPS, TG, ESI and MALDI mass spectrometry, which collectively proposed an uncommon

  3. Atomic and molecular layer activation of dielectric surfaces

    Science.gov (United States)

    Senkevich, John Joseph

    Strong interaction between the material deposit and substrate is critical to stable deposits and interfaces. The work presented here focuses on the surface activation of dielectric surfaces and oxidized metal surfaces to promote the chemisorption of palladium (II) hexafluoroacetylacetonate (PdII (hfac)2). The goal is to develop reliable, robust metallization protocols, which enable strong interactions between the metal and substrate. SiO2, air exposed Ta, Trikon, and SiLK were activated with sulfur or phosphorus. Two types of activations were developed; one based on self-assembled chemistry, and the other a plasma-assisted process. Activation of the surface using self-assembly techniques was carried out using mercaptan-terminated silane and tetrasulfide silane. The resulting films were characterized by variable angle spectroscopic ellipsometry, contact angle goniometry, and X-ray photoelectron spectroscopy. Tetrasulfide silane sources films exhibit self-limiting behavior, even in the presence of water vapor; whereas mercaptan-terminated silane sourced films tend to be thicker. The surface activations using atomic layers of sulfur and phosphorus were carried out in a rf plasma chamber using hydrogen sulfide and phosphine sources, respectively. The activations were studied as functions of rf power, system pressure, and substrate material. Results show that higher rf powers and lower system pressures promote greater surface coverages by sulfur with a reduced oxidation state. The activated dielectrics show evidence of PdII(hfac)2 chemisorption, in contrast to non-activated surfaces. The binding energy shift of the Pd3d 5/2 XPS peak towards elemental Pd provides evidence for the dissociative chemisorption of PdII(hfac)2. The extent of dissociation depends on the substrate temperature and the activation method used. The conclusions of the work presented here have implications for metallization using highly polarizable transition metals. Specifically, it can be applied to

  4. Sumpor u ugljenu (Sulphur in Coal

    Directory of Open Access Journals (Sweden)

    Rađenović, A.

    2004-12-01

    Full Text Available The presence of sulphur in coal possesses important environmetal problems in its usage. The sulphur dioxide (S02 emissions produced during coal combustion account for a significant proportion of the total global output of anthropogenic SO2. The extent of sulphur separation depends on several variables such as the form of sulphur in coal, intimacy of contact between minerals and the products of devolatilization. The total sulphur in coal varies in the range of 0.2 - 11 wt %, although in most cases it is beetwen 1 and 3 wt %. Sulphur occurs in a variety of both inorganic and organic forms. Inorganic sulphur is found mainly as iron pyrite, marcasite, pyrrhotite, sphalerite, galena, chalcopirite and as sulphates (rarely exceeds w = 0,1 %. Organic sulphur is found in aromatic rings and aliphatic functionalities usually as mercaptans, aliphatic and aryl sulfides, disulfides and thiophenes. Organic and pyritic sulphur quantities depend on coal rank. Higher rank coals tend to have a high proportion of labile sulphur. All the organic sulphur is bivalent and it is spread throughout the organic coal matrix. Sulphur occurs in all the macerals and most minerals. Vitrinite contains the major part of organic sulphur and metals. Elemental sulphur is produced during coal weathering. The depolymerization methods as pyrolysis and hydrogenation are very drastic methods wich change the structure of the coal and the sulphur groups. In the case of pyrolysis, high levels of desulphurization, in chars and additional production of liquid hydrocarbon can be achieved. Thiophenes and sulphides were the major sulphur components of tars from coal pyrolysis. Hyrdogen sulphide and the lower mercaptans and sulphides were found in the volatile matters. Hydrogen sulphide and thiophenes are practically the only sulphur products of coal hydrogenation. H2S is produced in char hydrodesulphurization. A number of options are available for reducing sulphur emissions including the

  5. Analysis of Relative Concentration of Ethanol and Other Odorous Compounds (OCs) Emitted from the Working Surface at a Landfill in China

    Science.gov (United States)

    Li, Dong; Lu, Wenjing; Liu, Yanjun; Guo, Hanwen; Xu, Sai; Ming, Zhongyuan; Wang, Hongtao

    2015-01-01

    Estimating odor emissions from landfill sites is a complicated task because of the various chemical and biological species that exist in landfill gases. In this study, the relative concentration of ethanol and other odorous compounds emitted from the working surface at a landfill in China was analyzed. Gas sampling was conducted at the landfill on a number of selected days from March 2012 to March 2014, which represented different periods throughout the two years. A total of 41, 59, 66, 54, 63, 54, 41, and 42 species of odorous compounds were identified and quantified in eight sampling activities, respectively; a number of 86 species of odorous compounds were identified and quantified all together in the study. The measured odorous compounds were classified into six different categories (Oxygenated compounds, Halogenated compounds, Terpenes, Sulfur compounds, Aromatics, and Hydrocarbons). The total average concentrations of the oxygenated compounds, sulfur compounds, aromatics, halogenated compounds, hydrocarbons, and terpenes were 2.450 mg/m3, 0.246 mg/m3, 0.203 mg/m3, 0.319 mg/m3, 0.530 mg/m3, and 0.217 mg/m3, respectively. The relative concentrations of 59 odorous compounds with respect to the concentration of ethyl alcohol (1000 ppm) were determined. The dominant contaminants that cause odor pollution around the landfill are ethyl sulfide, methyl mercaptan, acetaldehyde, and hydrogen sulfide; dimethyl disulfide and dimethyl sulfide also contribute to the pollution to a certain degree. PMID:25769100

  6. Comparison of three methods for accurate quantification of hydrogen sulfide during fermentation

    International Nuclear Information System (INIS)

    Ugliano, Maurizio; Henschke, Paul A.

    2010-01-01

    Two analytical approaches for the rapid measurement of hydrogen sulfide (H 2 S) have been compared to a reference method for their potential application as a rapid procedure for the quantification of H 2 S formed during alcoholic fermentations. In one case, silver nitrate, lead acetate, and mercuric chloride selective detector tubes for the analysis of H 2 S in air were investigated. In the other case, a commercially available kit for the diagnosis of nitrogen starvation in wine fermentations, which is based on the detection of H 2 S, was investigated. Both methods exhibited excellent linearity of response, but the mercuric chloride tube was found to suffer from interferences due to the concomitant presence of mercaptans, which resulted in erroneous H 2 S quantification. A comparative study between the two methods studied and the cadmium hydroxide/methylene blue reference method commonly used to monitor H 2 S indicate that the two new methods displayed better recoveries at low H 2 S concentrations, besides being more rapid and economical. The two new methods were successfully used to quantify production of H 2 S in different grape juice fermentations. The suitability of each method for the study of specific aspects of H 2 S production during fermentation is discussed.

  7. Halitosis: An oral microbial faction

    Directory of Open Access Journals (Sweden)

    Rajiv Saini

    2010-01-01

    Full Text Available Halitosis is a widespread condition and believed to affect one-quarter of the population around the world; also, most people have this condition from time to time. Breath malodour may be an important factor in social communication, and therefore may be the origin of concern not only for a possible health condition but also for frequent psychological alterations, leading to social and personal isolation. The most conspicuous malodorous compounds are termed volatile sulphur compounds (VSCs, with hydrogen sulphide, methyl mercaptan, and dimethyl sulphide accounting for roughly 90% of the VSCs. A number of oral bacteria, especially Gram-negative anaerobic species found in the subgingival plaque, produce a diverse array of malodorous compounds as byproducts of their metabolism, including VSCs and short-chain organic acids. Assessment and management of halitosis is of paramount importance in enhancing the overall health; moreover, dentists play a significant role in combating halitosis by reducing the oral microbial stack. Thus, the aim of the present review was to describe the aetiological factors, assessment tools, and therapeutic approaches related to halitosis.

  8. Physico-chemical studies of effluents and emission of ghee/edible oil industries in Pakistan

    International Nuclear Information System (INIS)

    Ahmed, I.; Ali, S.; Jan, M.R.

    1999-01-01

    Samples of the effluents from various Ghee/Edible Oil Industries were collected on fortnightly basis from July 1993 to June 1994 and the emissions from January to April 1994. Parameters such as temperature, pH, conductivity, total dissolved solids (TDS), total suspended solids (TSS), total alkalinity total acidity, total hardness, chemical oxygen demand (COD). chlorides, sulphates, phosphates, silica, calcium magnesium, sodium, and iron were determined in the effluents, Trace metals like copper, manganese, nickel, and zinc were determined by atomic absorption spectroscopy, whereas SO/sub 2/, CO CO/sub 2/, hydrocarbons, hydrogen, nitrogen, oxygen and argon were examined in the flue gases by Gas Chromatography and other standard techniques such as Orsat Gas Analyzer and Dragger Detection Tubes. Remedial measures were suggested for the pollutants exceeding the National Environmental Quality Standards, (NEQS). Parameters like chlorine, ammonia, sulphides, arsenic, cadmium, chromium, cobalt, lead and tin were also analyzed in the effluents and were found to be nil or below the detection limit, while particulate matters, HCl, chlorine, HF, H/sub 2/S, mercaptans and NH/sub 3/ were found to be nil in the flue gases. (author)

  9. Synthesis of hydroxy thio-ether derivatives of vegetable oil.

    Science.gov (United States)

    Sharma, Brajendra K; Adhvaryu, A; Erhan, S Z

    2006-12-27

    Bio-based additives are desirable commodities due to their eco-friendly nature. These additives can demonstrate physical and chemical properties comparable to those of conventional mineral oil-based products. Sulfur incorporated triacylglycerol can function as an antiwear/antifriction additive for lubricants. The synthesis of four useful hydroxy thio-ether derivatives of vegetable oils, from commercially available epoxidized soybean oil and common organic thiols, is reported in this paper. The common thiols used herein were 1-butanethiol, 1-decanethiol, 1-octadecanethiol, and cyclohexyl mercaptan. Currently, there is no reported literature describing the synthesis of hydroxy thio-ether derivatives of vegetable oil. The reaction was monitored, and products were confirmed by NMR and FTIR spectroscopies. Experimental conditions involving various thiols, solvent, catalyst amount, time, and temperature were optimized for research quantity and laboratory scale-up. The synthetic process retains the vegetable oil structure, eliminates polyunsaturation in the molecule, and adds polar functional groups on triacylglycerol. These products can be used as agriculturally-based antiwear additives for lubricant applications.

  10. Catalytic Activity Studies of Vanadia/Silica–Titania Catalysts in SVOC Partial Oxidation to Formaldehyde: Focus on the Catalyst Composition

    Directory of Open Access Journals (Sweden)

    Niina Koivikko

    2018-02-01

    Full Text Available In this work, silica–titania supported catalysts were prepared by a sol–gel method with various compositions. Vanadia was impregnated on SiO2-TiO2 with different loadings, and materials were investigated in the partial oxidation of methanol and methyl mercaptan to formaldehyde. The materials were characterized by using N2 physisorption, X-ray diffraction (XRD, X-ray fluorescence spectroscopy (XRF, X-ray photoelectron spectroscopy (XPS, Scanning transmission electron microscope (STEM, NH3-TPD, and Raman techniques. The activity results show the high importance of an optimized SiO2-TiO2 ratio to reach a high reactant conversion and formaldehyde yield. The characteristics of mixed oxides ensure a better dispersion of the active phase on the support and in this way increase the activity of the catalysts. The addition of vanadium pentoxide on the support lowered the optimal temperature of the reaction significantly. Increasing the vanadia loading from 1.5% to 2.5% did not result in higher formaldehyde concentration. Over the 1.5%V2O5/SiO2 + 30%TiO2 catalyst, the optimal selectivity was reached at 415 °C when the maximum formaldehyde concentration was ~1000 ppm.

  11. A High-Yield Synthesis of Chalcopyrite CuInS2 Nanoparticles with Exceptional Size Control

    Directory of Open Access Journals (Sweden)

    Chivin Sun

    2009-01-01

    Full Text Available We report high-yield and efficient size-controlled syntheses of Chalcopyrite CuInS2 nanoparticles by decomposing molecular single source precursors (SSPs via microwave irradiation in the presence of 1,2-ethanedithiol at reaction temperatures as low as 100°C and times as short as 30 minutes. The nanoparticles sizes were 1.8 nm to 10.8 nm as reaction temperatures were varied from 100°C to 200°C with the bandgaps from 2.71 eV to 1.28 eV with good size control and high yields (64%–95%. The resulting nanoparticles were analyzed by XRD, UV-Vis, ICP-OES, XPS, SEM, EDS, and HRTEM. Titration studies by 1H NMR using SSP 1 with 1,2-ethanedithiol and benzyl mercaptan were conducted to elucidate the formation of Chalcopyrite CuInS2 nanoparticles.

  12. Metal-coordinating substrate analogs as inhibitors of metalloenzymes.

    Science.gov (United States)

    Holmquist, B; Vallee, B L

    1979-01-01

    A group of active-site metal coordinating inhibitors of zinc proteases (carboxypeptidase A, thermolysin, Bacillus cereus neutral protease, and angiotensin-converting enzyme) have been synthesized and their properties investigated. Their general structures are R-SH and R-NH-PO2(O phi)H, where-S- or -O- serve as metal ligands and R refers to an amino acid or peptide group designed to interact with substrate recognition sites. These inhibitors can be extremely potent; thus, N-(2-mercaptoacetyl)-D-phenylalanine, e.g., inhibits carboxypeptidase A with a Kiapp of 2.2 x 10(-7) M. The spectral response of cobalt(II)-substituted thermolysin or carboxypeptidase A to the sulfur-containing inhibitors signals the direct interaction of the mercaptan with the metal. An S leads to Co(II) charge transfer band is generated near 340 nm and is detected by absorption, circular dichroism, and magnetic circular dichroism. The cobalt(II) spectra indicate both inner sphere coordination with sulfur and 4-coordination in the enzyme-inhibitor complex. Thus, the metal undergoes a simple substitution reaction, the inhibitor most likely displacing water at the fourth coordination site. PMID:230502

  13. Determination of atmospheric gaseous and particulate sulfur compounds. [Atmospheric SO/sub 2/ sampling, calibration, and data processing

    Energy Technology Data Exchange (ETDEWEB)

    Tanner, R.L.; Forrest, J.; Newman, L.

    1977-01-01

    The corrosive influence of atmospheric sulfur compounds to man's health and his environment has been demonstratably costly. Damage to building materials, textiles, animals, plants, and artworks have been well documented and can in some cases be directly translated into financial loss. Indirect effects such as contribution to respiratory disease and increased death rates are more subtle but no less real. For both economic and ecological reasons, it has become imperative that atmospheric concentrations be minimized. Anthropogenic sources of atmospheric sulfur compounds are principally the combustion of fossil fuels, which produce sulfur dioxide along with several percent of sulfur trioxide. The predominant form of atmospheric gaseous sulfur is sulfur dioxide, accompanied by small amounts of hydrogen sulfide and organic sulfur compounds such as mercaptans and sulfides. Aerosol sulfur exists primarily as sulfates, including bisulfate and sulfuric acid. The core of any monitoring system is the analytical instrument or technique. Methods for SO/sub 2/ sampling, calibration, and data acquisition and reduction are reviewed. 305 references.

  14. Parametric and comparative study of the impact of waste pollutants in groundwater: the case of the district of Abidjan (Côte d'Ivoire) and polluted site in Switzerland

    Science.gov (United States)

    Agnès Kouamé, Amenan; Jaboyedoff, Michel; Derron, Marc-Henri

    2013-04-01

    Groundwater as natural resources is one of the main sources of water for agricultural, industrial and domestic in developed or developing countries. However this resource, which was considered of good quality, is now threatened by various sources of contamination by human activities. This is the case of the District of Abidjan which has been the victim of toxic waste in 2006 and of an alpine valley in Western Switzerland. Groundwater from these two sites is located in sandy and unconfined aquifers. In fact, the pollutant transport in porous media is influenced by a variety of physical, chemical or biological, complex and interdependent. In Switzerland, where data are available, we simulated steady-state flow and tetrachloroethene transport with a good result showing the tetrachloroethene plume. While in Abidjan, where the data are insufficient, we developed in steady and transient states, flow and contaminants transport models in order to predict the likely evolution of the contaminants in the basement. Contaminants are composed of a very high contents of hydrogen sulfide, organochlorines, sulfur, mercaptan sulfur, and hydrocarbons such as olefins, Paraffins. We made two parametric and comparative studies. The probability of contamination of groundwater is observed over time, taking into account the input parameters of the model and some assumptions.

  15. Lessons learned from the Sullivan tragedy : a regulator's point of view

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, A. [British Columbia Ministry of Energy, Mines and Petroleum Resources, Victoria, BC (Canada). Mining and Minerals Div

    2010-07-01

    In May of 2006, inspectors from the British Columbia Health and Safety Branch responded to fatalities at a waste dump at Tech Cominco's Sullivan mine near Kimberley, British Columbia. Four persons died in the water monitoring shed. The immediate cause of the accident and its investigation were reviewed. Initial sampling using an electronic gas detector and probe showed depressed oxygen levels. There were no noticeable odours of hydrogen sulphide, sulphur dioxide or methyl mercaptan. Velocimetry readings indicated an inflow of air into the sump through the inlet pipe. Initial findings showed that the depleted oxygen levels were due to an oxidation of sulphidic waste rock that occurred upstream of the inlet drainage pipe inside the dump. A reaction of acid with carbonates in the waste dump rock generated high, but not lethal, carbon dioxide levels. This presentation reviewed the recommendations of the Sullivan Inquest Jury and the resulting changes in policy, and revisions to the Health, Safety and Reclamation Code for the province. 3 refs., 6 figs.

  16. Identification and quantification of nuisance odors at a trash transfer station.

    Science.gov (United States)

    Curren, Jane; Hallis, Samantha A; Snyder, Cherie Cher L; Suffet, Irwin Mel H

    2016-12-01

    The objective of this study was to evaluate the effectiveness of a modified Odor Profile Method (OPM) at a trash transfer station (TTS). An updated Landfill Odor Wheel was used to define odor character and distinguish among odor sources. The Flavor Profile Analysis (FPA) intensity scale was used to rank the relative intensity of the various odor characters defined by the odor wheel and to understand how each odor profile changed off site. Finally, the odor wheel was used to select the appropriate chemical analysis to identify the odorants causing the odors identified by the human panelists. The OPM was demonstrated as an effective tool for characterizing and distinguishing odor sources at a TTS. Municipal solid waste (MSW) odors were characterized as rancid, sulfur, and fragrant; rancid odors were dominant in the odor profile on-site, while sulfur odors dominated off-site. Targeted chemical analysis was used to identify odorants potentially responsible for odors at the site. Methyl mercaptan (rotten vegetable) and hydrogen sulfide (rotten egg) were identified as the odorants most likely to be responsible for the sulfur odors at the site. Acetaldehyde (sweet, fruity), acetic acid (vinegar), and butyric acid (rancid) were identified as the odorants mostly likely to be causing the rancid and sour odors. Terpenes/pine odors were observed near the greenwaste pile. Results confirm that the OPM, together with properly selected chemical analyses, can be a useful tool for identifying and quantifying the sources of odors. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. An Internalin A Probe-Based Genosensor for Listeria monocytogenes Detection and Differentiation

    Directory of Open Access Journals (Sweden)

    Laura Bifulco

    2013-01-01

    Full Text Available Internalin A (InlA, a protein required for Listeria monocytogenes virulence, is encoded by the inlA gene, which is only found in pathogenic strains of this genus. One of the best ways to detect and confirm the pathogenicity of the strain is the detection of one of the virulence factors produced by the microorganism. This paper focuses on the design of an electrochemical genosensor used to detect the inlA gene in Listeria strains without labelling the target DNA. The electrochemical sensor was obtained by immobilising an inlA gene probe (single-stranded oligonucleotide on the surfaces of screen-printed gold electrodes (Au-SPEs by means of a mercaptan-activated self-assembled monolayer (SAM. The hybridisation reaction occurring on the electrode surface was electrochemically transduced by differential pulse voltammetry (DPV using methylene blue (MB as an indicator. The covalently immobilised single-stranded DNA was able to selectively hybridise to its complementary DNA sequences in solution to form double-stranded DNA on the gold surface. A significant decrease of the peak current of the voltammogram (DPV upon hybridisation of immobilised ssDNA was recorded. Whole DNA samples of L. monocytogenes strains could be discriminated from other nonpathogenic Listeria species DNA with the inlA gene DNA probe genosensor.

  18. A new ppb-gas analyzer by means of GC-ion mobility spectrometry (GC-IMS)

    International Nuclear Information System (INIS)

    Leonhardt, J.W.

    2003-01-01

    IMS-detectors are using beta-sources like tritium or nickel-63. This detection principle uses fast ion-molecular reactions between air cluster ions, produced by beta ionization and the analyte. The system works at normal pressure, the very high sensitivity and selectivity is used widely in industry, research, medicine and environmental control. In the last few years especially, small tritium sources were reduced to a level of some 50 MBq, which is 20 times less than the exemption levels for these sources. One of the handicaps of that technology is the problem of cross sensitivities. To overcome these problems a special GC-column of 1 m length has been included into the gas inlet and mixtures of compounds get separated by their retention times before entering the drift sensor. By means of that method a new analytical quality of IMS is arrived. The application of these analytical devices got a spin off in the last year. The main applications being discussed are as follows: (1) anti terror systems in buildings and facilities, (2) working place monitoring in chemical industry, (3) microelectronics: HF, HCl, Cl 2 , NMP, NH 3 , NO 2 , SO 2 , (4) environment: NH 3 , HCN, HCl, CH 2 O, organic compounds, SO 2 , NO 2 , (5) gas and petrol: gas-carottage, H 2 S, mercaptans, (6) household, furniture: solvents, clue, organic vapour from furniture, and (7) health care: diagnostics of various diseases. (author)

  19. Processing and performance of self-healing materials

    International Nuclear Information System (INIS)

    Tan, P S; Bhattacharyya, D; Zhang, M Q

    2009-01-01

    Two self-healing methods were implemented into composite materials with self-healing capabilities, using hollow glass fibres (HGF) and microencapsulated epoxy resin with mercaptan as the hardener. For the HGF approach, two perpendicular layers of HGF were put into an E-glass/epoxy composite, and were filled with coloured epoxy resin and hardener. The HGF samples had a novel ball indentation test method done on them. The samples were analysed using micro-CT scanning, confocal microscopy and penetrant dye. Micro-CT and confocal microscopy produced limited success, but their viability was established. Penetrant dye images showed resin obstructing flow of dye through damage regions, suggesting infiltration of resin into cracks. Three-point bend tests showed that overall performance could be affected by the flaws arising from embedding HGF in the material. For the microcapsule approach, samples were prepared for novel double-torsion tests used to generate large cracks. The samples were compared with pure resin samples by analysing them using photoelastic imaging and scanning electron microscope (SEM) on crack surfaces. Photoelastic imaging established the consolidation of cracks while SEM showed a wide spread of microcapsules with their distribution being affected by gravity. Further double-torsion testing showed that healing recovered approximately 24% of material strength.

  20. Advanced oxidation processes for treatment of petroleum refinery sour waters; Processos oxidativos avancados para tratamento de aguas acidas de refinaria de petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Antonio V.; Coelho, Alessandra D.; Sant' Anna Junior, Geraldo L.; Dezotti, Marcia [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE). Programa de Engenharia Quimica

    2004-07-01

    The characteristics of the waste water generated by the petroleum refineries are related to the type and amount of processed oil, to the nature and the efficiency of the refining operation. The effluents are composed basically of oily waters, originating from of the contact with the oil. Among them, the current of sour water is one of the most preoccupying due to its composition: sulfide, ammonia, mercaptans, phenol, dissolved oil, basic pH, dissolved organic carbon (DOC) and chemical oxygen demand (COD) high. The aim of this work was to evaluate the advanced oxidation processes to degrade sour water (UV radiation, H{sub 2}O{sub 2} and H{sub 2}O{sub 2}/UV, photocatalysis, Fenton and photo-Fenton). All process, except Fenton and photo-Fenton, did not supply satisfactory results, reducing 25% of initial DOC, which it is of 450 mg/L. The results using the Fenton process reached removal of 50% of the initial COD, and when photo- Fenton process obtaining removal of 90%. The processes Fenton and photo-Fenton were shown capable to degrade this kind of waste water, minimizing the environmental problems and corrosion, operating as a pre-treatment for the biological system, or acting alone to degrade the organic matter contained, seeking the water reuse. The effluent used in this work came from Duque de Caxias Refinery (Reduc)/PETROBRAS. (author)

  1. The long-term effect of a zinc acetate and chlorhexidine diacetate containing mouth rinse on intra-oral halitosis-A randomized clinical trial.

    Science.gov (United States)

    Erovic Ademovski, Seida; Mårtensson, Carina; Persson, Gösta Rutger; Renvert, Stefan

    2017-10-01

    To evaluate the long-term effects of a zinc acetate and chlorhexidine diacetate mouth rinse (Zn/CHX) on intra-oral halitosis. Forty-six adults with intra-oral halitosis were randomized into a 6-month, double-blind, placebo-controlled clinical study. The presence of intra-oral halitosis was evaluated at baseline, 3 and 6 months after treatment by assessment of organoleptic score (OLS) and by total volatile sulphur compounds (T-VSC), hydrogen sulphide (H 2 S) and methyl mercaptan (MM) concentrations in exhaled air. A Zn/CHX mouth rinse provided significantly better control of intra-oral halitosis than a placebo mouth rinse. At 3 and 6 months, individuals rinsing with the Zn/CHX rinse presented with reductions of the OLS, T-VSC (p oral halitosis (i.e. H 2 S oral halitosis, assessed both objectively and subjectively. With regular rinsing, the effect was sustained for 6 months. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  2. Chemistry of the organic-rich hot core G327.3-0.6

    Science.gov (United States)

    Gibb, E.; Nummelin, A.; Irvine, W. M.; Whittet, D. C.; Bergman, P.; Ferris, J. P. (Principal Investigator)

    2000-01-01

    We present gas-phase abundances of species found in the organic-rich hot core G327.3-0.6. The data were taken with the Swedish-ESO Submillimetre Telescope (SEST). The 1-3 mm spectrum of this source is dominated by emission features of nitrile species and saturated organics, with abundances greater than those found in many other hot cores, including Sgr B2 and OMC-1. Population diagram analysis indicates that many species (CH3CN, C2H3CN, C2H5CN, CH3OH, etc.) have hot components that originate in a compact (2") region. Gas-phase chemical models cannot reproduce the high abundances of these molecules found in hot cores, and we suggest that they originate from processing and evaporation of icy grain mantle material. In addition, we report the first detection of vibrationally excited ethyl cyanide and the first detection of methyl mercaptan (CH3SH) outside the Galactic center.

  3. Influence of heavy crude oil refining about the mains characteristics of jet fuel; Influencia do refino de petroleos pesados sobre as principais caracteristicas do combustivel de aviacao

    Energy Technology Data Exchange (ETDEWEB)

    Om, Neyda [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Escola de Quimica; Cavado, Alberto; Reyes, Yordanka [Centro de Pesquisas do Petroleo, Cidade de Havana (Cuba); Salazar, Rodolfo [Centro de Eletromagnetismo Aplicado, Cidade de Havana (Cuba); Dominguez, Zulema [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE)

    2004-07-01

    The aviation technology in the world, is to use gas turbines engines feted for fuel type Jet A1. The main exigency of quality for this products is concentrated in extreme security and secure answer during the functioning. The conductivity and thermal stability to oxidation are the principals characteristics to assure these quality exigencies. The use of additives is the methods most used for establish the quality for international specification. The incorporation of heavy crude oils in mixtures to produce fuels has caused a diminution of the quality of the derivatives produced. High viscosity, density and high sulfur content in the heavy crude oils affect some of properties of the jet fuel, influencing in its composition, increasing the mercaptanes and total sulfur content, getting a jet fuel unstable, with low conductivity and highly corrosive. So, for obtain the quality required internationally is necessary use additives. This paper study how the heavy crude oils affect the conductivity and the thermal stability of the jets fuels type Jet A1. Also analyze of the use of dissipater electrostatic and antioxidants additives, to improve these properties in the jet fuel. (author)

  4. Hot-atom synthesis of organic compounds on Jupiter

    Science.gov (United States)

    Lewis, J. S.; Fegley, B., Jr.

    1979-01-01

    Results of recent laboratory 'simulations' of photochemical processes on Jupiter are combined with available data on mixing rates and exposure times in the Jovian atmosphere to give quantitative predictions of the rate at which hot-atom reactions produce organic molecules. It is shown that abstraction reactions on methane by hot H atoms from solar UV photolysis of H2S will produce no more than 4 times 10 to the -17th power g/sq cm/sec for a steady-state mole fraction of total organics of approximately 10 to the -16th power. This is roughly 10 to the 7th power times less than the limit of detection of the most sensitive gas analysis experiments ever flown on a spacecraft. By far the most common organic molecule produced by this mechanism is CH3SH, methyl mercaptan, which is produced at a rate at least 600 times smaller than the rate of production of ethane by direct photolysis of CH4 at high altitudes.

  5. Use of Hg-Electroplated-Pt Ultramicroelectrode for Determining Elemental Sulphur in Naphtha Samples

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo de Andrade

    2012-01-01

    Full Text Available This paper describes the applicability of a Hg-electroplated-Pt ultramicroelectrode in the quantification of elemental sulphur in naphtha samples by square-wave voltammetry. A reproducible deposition methodology was studied and is reported in this paper. This methodology is innovative and relies on the quality of the mercury stock solution to obtain reproducible surfaces required for the analytical methodology. All analyses were performed using a Hg-electroplated-Pt ultramicroelectrode (Hg-Pt UME due to the low sensibility of such devices to ohmic drops in resistive solutions. The responses of the peak areas in voltammetric experiments were linear in all of the range studied. The method developed here is accurate and reproducible, with a detection limit of 0.010 mg L−1 and a good recovery range for both standard solutions of elemental sulphur (85 to 99% and real naphtha sample (79%. These results attest to the potential for the application of this electroanalytical methodology in determining elemental sulphur in naphtha samples containing mercaptans and disulphides.

  6. Comparative Study on the Characteristics of Weissella cibaria CMU and Probiotic Strains for Oral Care

    Directory of Open Access Journals (Sweden)

    Hye-Jin Jang

    2016-12-01

    Full Text Available Probiotics have been demonstrated as a new paradigm to substitute antibiotic treatment for dental caries, gingivitis, and chronic periodontitis. The present work was conducted to compare the characteristics of oral care probiotics: Weissella cibaria CMU (Chonnam Medical University and four commercial probiotic strains. Survival rates under poor oral conditions, acid production, hydrogen peroxide production, as well as inhibition of biofilm formation, coaggregation, antibacterial activity, and inhibition of volatile sulfur compounds were evaluated. The viability of W. cibaria CMU was not affected by treatment of 100 mg/L lysozyme for 90 min and 1 mM hydrogen peroxide for 6 h. Interestingly, W. cibaria produced less acid and more hydrogen peroxide than the other four probiotics. W. cibaria inhibited biofilm formation by Streptococcus mutans at lower concentrations (S. mutans/CMU = 8 and efficiently coaggregated with Fusobacterium nucleatum. W. cibaria CMU and two commercial probiotics, including Lactobacillus salivarius and Lactobacillus reuteri, showed high antibacterial activities (>97% against cariogens (S. mutans and Streptococcus sobrinus, and against periodontopathogens (F. nucleatum and Porphyromonas gingivalis. All of the lactic acid bacterial strains in this study significantly reduced levels of hydrogen sulfide and methyl mercaptan produced by F. nucleatum and P. gingivalis (p < 0.05. These results suggest that W. cibaria CMU is applicable as an oral care probiotic.

  7. Observations of some oxygen-containing and sulfur-containing organic molecules in cold dark clouds

    Science.gov (United States)

    Irvine, W. M.; Friberg, P.; Kaifu, N.; Kitamura, Y.; Kawaguchi, K.

    1989-01-01

    Observations of nine oxygen- and sulfur-containing organic molecules have been made toward the cold dark clouds TMC-1 and L134N. The presence of paraketene (H2C2O) in TMC-1 is confirmed for orthoketene, and has been observed for the first time and a total ketene column density of about 10 to the 13th/sq cm is found. Thioformaldehyde (H2CS) is easily detectable in both TMC-1 and L134N, with a column density about five times larger in the former source. The fractional abundance of ketene is comparable to the predictions of ion-molecule chemistry, while that of thioformaldehyde in TMC-1 is one to two orders of magnitude greater than that expected from such models at steady state. Interstellar sulfur chemistry thus continues to be poorly understood. Upper limits are set for the column densities of formic acid (HCOOH), vinyl alcohol (CH2CHOH), methyl formate (HCO2CH3), formamide (NH2CHO), methyl mercaptan (CH3SH), isothiocyanic acid (HNCS), and thioketene (H2C2S) in both sources.

  8. Novel reuterin-related compounds suppress odour by periodontopathic bacteria.

    Science.gov (United States)

    Fujiwara, N; Murakami, K; Nakao, M; Toguchi, M; Yumoto, H; Amoh, T; Hirota, K; Matsuo, T; Sano, S; Ozaki, K; Miyake, Y

    2017-05-01

    Halitosis is caused by volatile sulphur compounds including methyl mercaptan (CH 3 SH) in the oral cavity and is a serious problem that limits interpersonal social communication. The aim of study was to evaluate the effects of reuterin-related compounds (RRCs) on halitosis-related periodontopathic bacteria in vitro. RRC-01, RRC-02 and RRC-03 (32 and 64 μg ml -1 ) in culture media containing Fusobacterium nucleatum JCM8523 and Porphyromonas gingivalis ATCC33277 were used. The effects of RRCs on CH 3 SH production and detectable odour by F. nucleatum and P. gingivalis were examined by CH 3 SH production assay and organoleptic test, respectively. The number of bacterial cells was also measured using an ATP assay. In P. gingivalis treated with RRCs, the expression of mgl gene, which is responsible for CH 3 SH production, was examined by qRT-PCR. CH 3 SH production and the score of detectable odour from F. nucleatum and P. gingivalis culture media containing RRCs were significantly lower than that without RRCs (P < 0.05). The expression of mgl gene in P. gingivalis was significantly downregulated by RRC-01 (P < 0.01), but not by RRC-02 or RRC-03. RRCs are potent oral care products for preventing halitosis via reducing CH 3 SH production. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  9. Comparison of oxidized and reduced glutathione in the bread-making qualities of rice batter.

    Science.gov (United States)

    Yano, Hiroyuki

    2012-02-01

    The demand for gluten-free bread is growing as the recognition of celiac disease and wheat allergy has increased worldwide. In our previous study, reduced glutathione (GSH) was found to improve the gas-retaining properties of rice batter used for gluten-free bread. In this article, oxidized glutathione (GSSG) was shown to have the same effect. Moreover, sensory tests revealed that GSSG bread had a significantly reduced sulfurous odor. Analyses by a gas chromatography-flame photometric detector demonstrated the presence of hydrogen sulfide and methyl mercaptan in the headspace of GSH bread, and also their significant reduction in GSSG bread. The viscoelastic properties and microstructures of GSSG and GSH bread did not noticeably differ. These observations suggest the usefulness of GSSG in making gluten-free rice bread and extend our knowledge of the use of glutathione in food processing. Practical Application: Glutathione, a widely-distributed peptide in cells, improves the bread-making quality of gluten-free rice batter. While both the reduced (GSH) and oxidized (GSSG) glutathione are effective, GSSG-bread has significantly reduced sulfurous odor compared to GSH-bread. © 2012 Institute of Food Technologists®

  10. A genome-wide study on the perception of the odorants androstenone and galaxolide.

    Science.gov (United States)

    Knaapila, Antti; Zhu, Gu; Medland, Sarah E; Wysocki, Charles J; Montgomery, Grant W; Martin, Nicholas G; Wright, Margaret J; Reed, Danielle R

    2012-07-01

    Twin pairs and their siblings rated the intensity of the odorants amyl acetate, androstenone, eugenol, Galaxolide, mercaptans, and rose (N = 1573). Heritability was established for ratings of androstenone (h (2) = 0.30) and Galaxolide (h(2) = 0.34) but not for the other odorants. Genome-wide association analysis using 2.3 million single nucleotide polymorphisms indicated that the most significant association was between androstenone and a region without known olfactory receptor genes (rs10966900, P = 1.2 × 10(-7)). A previously reported association between the olfactory receptor OR7D4 and the androstenone was not detected until we specifically typed this gene (P = 1.1 × 10(-4)). We also tested these 2 associations in a second independent sample of subjects and replicated the results either fully (OR7D4, P = 0.00002) or partially (rs10966900, P = 0.010; N = 266). These findings suggest that 1) the perceived intensity of some but not all odorants is a heritable trait, 2) use of a current genome-wide marker panel did not detect a known olfactory genotype-phenotype association, and 3) person-to-person differences in androstenone perception are influenced by OR7D4 genotype and perhaps by variants of other genes.

  11. Removal of odor originating from kitchen wastewater treatment facilities by activated carbon impregnated iodic acid; Chubo haisui shori shisetsu kara hasseisuru akushu no yososan tenchaku kasseitan ni yoru jokyo

    Energy Technology Data Exchange (ETDEWEB)

    Yano, H.; Hashimoto, S.; Yonemura, S. [Shimizu Corp., Tokyo (Japan); Shoda, M. [Research Laboratory of Resources Utilization, Yokohama (Japan)

    1997-07-10

    Activated carbon impregnated iodic acid (deodorant D) was developed as a new deodorant. Deodorization performance of deodorant D as well as three kinds of commercial activated carbons (deodorant A, B and C) was tested for odors originating from the kitchen wastewater treatment facilities of one commercial building. The odor exhausted from this facility was medium concentration between 422 and 31,620. The main odorous compounds were hydrogen sulfide (0.076 to 15.7 ppm) and methyl mercaptan (not detected to 0.081 ppm). The hydrogen sulfide contribution to the odor concentration was about 90%. The main apparatuses from which the odors were originating were the raw water tank and the pressurized flotation tank. The total odor emission rate was between 10{sup 4.9} and 10{sup 5.7} Nm{sup 3}/min. For the performance test for deodorants, fixed bed adsorption experimental equipment was used, and the breakthrough time of odor concentration and hydrogen sulfide were used as indexes. Correlation between the contact time and the breakthrough time was observed for all of the deodorants. For a contact time of 0.5 sec, the breakthrough times for odor concentration were D>C>B>A, and the breakthrough times for hydrogen sulfide were D>C>B>A. Effectiveness of activated carbon impregnated iodic acid was recognized. 11 refs., 7 figs., 7 tabs.

  12. Deodorization of garlic breath volatiles by food and food components.

    Science.gov (United States)

    Munch, Ryan; Barringer, Sheryl A

    2014-04-01

    The ability of foods and beverages to reduce allyl methyl disulfide, diallyl disulfide, allyl mercaptan, and allyl methyl sulfide on human breath after consumption of raw garlic was examined. The treatments were consumed immediately following raw garlic consumption for breath measurements, or were blended with garlic prior to headspace measurements. Measurements were done using a selected ion flow tube-mass spectrometer. Chlorophyllin treatment demonstrated no deodorization in comparison to the control. Successful treatments may be due to enzymatic, polyphenolic, or acid deodorization. Enzymatic deodorization involved oxidation of polyphenolic compounds by enzymes, with the oxidized polyphenols causing deodorization. This was the probable mechanism in raw apple, parsley, spinach, and mint treatments. Polyphenolic deodorization involved deodorization by polyphenolic compounds without enzymatic activity. This probably occurred for microwaved apple, green tea, and lemon juice treatments. When pH is below 3.6, the enzyme alliinase is inactivated, which causes a reduction in volatile formation. This was demonstrated in pH-adjusted headspace measurements. However, the mechanism for volatile reduction on human breath (after volatile formation) is unclear, and may have occurred in soft drink and lemon juice breath treatments. Whey protein was not an effective garlic breath deodorant and had no enzymatic activity, polyphenolic compounds, or acidity. Headspace concentrations did not correlate well to breath treatments. © 2014 Institute of Food Technologists®

  13. Case Study: Microbial Ecology and Forensics of Chinese Drywall-Elemental Sulfur Disproportionation as Primary Generator of Hydrogen Sulfide.

    Science.gov (United States)

    Tomei Torres, Francisco A

    2017-06-21

    Drywall manufactured in China released foul odors attributed to volatile sulfur compounds. These included hydrogen sulfide, methyl mercaptan, and sulfur dioxide. Given that calcium sulfate is the main component of drywall, one would suspect bacterial reduction of sulfate to sulfide as the primary culprit. However, when the forensics, i.e., the microbial and chemical signatures left in the drywall, are studied, the evidence suggests that, rather than dissimilatory sulfate reduction, disproportionation of elemental sulfur to hydrogen sulfide and sulfate was actually the primary cause of the malodors. Forensic evidence suggests that the transformation of elemental sulfur went through several abiological and microbial stages: (1) partial volatilization of elemental sulfur during the manufacture of plaster of Paris, (2) partial abiotic disproportionation of elemental sulfur to sulfide and thiosulfate during the manufacture of drywall, (3) microbial disproportionation of elemental sulfur to sulfide and sulfate resulting in neutralization of all alkalinity, and acidification below pH 4, (4) acidophilic microbial disproportionation of elemental sulfur to sulfide and sulfuric acid, and (5) hydrogen sulfide volatilization, coating of copper fixtures resulting in corrosion, and oxidation to sulfur dioxide.

  14. Comparison of three methods for accurate quantification of hydrogen sulfide during fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Ugliano, Maurizio, E-mail: maurizio.ugliano@awri.com.au [Australian Wine Research Institute, PO Box 197, Glen Osmond, SA 5064 (Australia); Henschke, Paul A. [Australian Wine Research Institute, PO Box 197, Glen Osmond, SA 5064 (Australia)

    2010-02-15

    Two analytical approaches for the rapid measurement of hydrogen sulfide (H{sub 2}S) have been compared to a reference method for their potential application as a rapid procedure for the quantification of H{sub 2}S formed during alcoholic fermentations. In one case, silver nitrate, lead acetate, and mercuric chloride selective detector tubes for the analysis of H{sub 2}S in air were investigated. In the other case, a commercially available kit for the diagnosis of nitrogen starvation in wine fermentations, which is based on the detection of H{sub 2}S, was investigated. Both methods exhibited excellent linearity of response, but the mercuric chloride tube was found to suffer from interferences due to the concomitant presence of mercaptans, which resulted in erroneous H{sub 2}S quantification. A comparative study between the two methods studied and the cadmium hydroxide/methylene blue reference method commonly used to monitor H{sub 2}S indicate that the two new methods displayed better recoveries at low H{sub 2}S concentrations, besides being more rapid and economical. The two new methods were successfully used to quantify production of H{sub 2}S in different grape juice fermentations. The suitability of each method for the study of specific aspects of H{sub 2}S production during fermentation is discussed.

  15. Fracture behaviour of a self-healing microcapsule-loaded epoxy system

    Directory of Open Access Journals (Sweden)

    2011-03-01

    Full Text Available The effect of temperature on the fracture behaviour of a microcapsule-loaded epoxy matrix was investigated. Microencapsulated epoxy and mercaptan-derivative healing agents were incorporated into an epoxy matrix to produce a polymer composite capable of self-healing. Maximum fracture loads were measured using the double-torsion method. Thermal aging at 55 and 110°C for 17 hours [hrs] was applied to heal the pre-cracked samples. The addition of microcapsules appeared to increase significantly the load carrying capacity of the epoxy after healing. Once healed, the composites achieved as much as 93–171% of its virgin maximum fracture load at 18, 55 and 110°C. The fracture behavior of the microcapsule- loaded epoxy matrix was influenced by the healing temperature. The high self-healing efficiency may be attributed to the result of the subsurface micro-crack pinning or deviation, and to a stronger microencapsulated epoxy and mercaptanderivative binder than that of the bulk epoxy. The results show that the healing temperature has a significant effect on recovery of load transferring capability after fracture.

  16. CNG acid-gas-removal process. Technical progress report 4 for the period 1 August 1981-31 October 1981

    Energy Technology Data Exchange (ETDEWEB)

    Adler, R.J.; Auyang, L.; Brown, W.R.; Cook, W.J.; Keyvani, M.; Liu, Y.C.

    1981-12-01

    Four tasks were active: design and construction of a bench-scale triple-point crystallizer; equilibrium data acquisition, crystallizer separation factors for several sulfur-containing molecules and trace contaminants, and slurry pumping. A new design for the CNG crystallizer has been completed. A control scheme was devised for the new design. Equipment sizing, selection, and procurement is in progress. Equilibrium data acquisition has been completed. Five component vapor-liquid equilibrium data for gas mixtures representative of BCR Bi-Gas and Exxon catalytic gasifier crude gases were measured. The experimental data agree very well with the equilibrium data estimated by computer calculations. Separation factors were determined for the binary systems carbon dioxide/hydrogen sulfide, carbon dioxide/carbonyl sulfide, carbon dioxide/ethane, carbon dioxide/ethylene, and carbon dioxide/methyl mercaptan. For each system, sharp separation was observed in one stage of crystallization. In the slurry pumping project the height of liquid leg between the free flashing surface and the pump centerline is being varied to determine the minimum suction head needed for pumping slurry. The pump in current use is a MICROPUMP gear pump.

  17. Occupational exposure to chemical and biological agents in the nonproduction departments of pulp, paper, and paper product mills: an international study.

    Science.gov (United States)

    Teschke, K; Ahrens, W; Andersen, A; Boffetta, P; Fincham, S; Finkelstein, M; Henneberger, P; Kauppinen, T; Kogevinas, M; Korhonen, K; Liss, G; Liukkonnen, T; Osvoll, P; Savela, A; Szadkowska-Stanczyk, I; Westberg, H; Widerkiewicz, K

    1999-01-01

    As part of an international epidemiological study of workers in the pulp and paper industry, previously unpublished exposure measurements were assembled in a database. This article describes 7293 measurements in nonproduction departments from 147 mills in 11 countries. The greatest variety of agents was measured in the maintenance, construction, and cleaning department, where high exposures to asbestos, chromium [VI] compounds, copper, mercury in urine, nitrogen dioxide, ozone, styrene, sulfur dioxide, trichloroethylene, and welding fumes were observed. Measurements in the storage, yard, loading, and shipping department indicated high exposures to asbestos, carbon monoxide, fungal spores, nitrogen oxides, sulfur dioxide, and total dust. The steam and power generation department had high exposures to methyl mercaptan, silica, and total dust. Measurements in process and effluent water treatment, laboratory and research, engineering, and office, administration, and cafeteria areas had few elevated exposures. Throughout the nonproduction departments, measurements of pulp-production chemicals such as chlorine and sulfur compounds tended to be low, with many below detection limits. There were some problems with the available data; in particular, detection limits were often not specified, and the data tended to be clustered in such a way that sources of exposure variability could not be distinguished. Despite these problems, the data provide new insight into the exposures of nonproduction pulp and paper industry personnel.

  18. A randomised clinical trial to assess control of oral malodour by a novel dentifrice containing 0.1%w/w o-cymen-5-ol, 0.6%w/w zinc chloride.

    Science.gov (United States)

    Payne, David; Gordon, Jenny J; Nisbet, Stephanie; Karwal, Ritu; Bosma, Mary Lynn

    2011-08-01

    To assess the ability of a 0.1% w/w o-cymen-5-ol/ 0.6% w/w zinc chloride/ sodium fluoride dentifrice to control oral malodour compared to a sodium fluoride control dentifrice. Following baseline measurement of oral volatile sulfur compounds (VSCs), the subjects brushed twice daily for 1 week with either the test or control dentifrice. The VSC concentration in breath samples was monitored up to 12 hours post-treatment, by gas chromatography (GC). 75 subjects were included in the efficacy analysis. Relative to the sodium fluoride control dentifrice group the o-cymen-5-ol/ zinc chloride/ sodium fluoride dentifrice exhibited statistically significant reductions (Phydrogen sulfide, methyl mercaptan and total measured VSCs immediately and after 1, 2, 3 and 12 (overnight) hours post-treatment. The results of the present clinical study demonstrated that the use of the 0.1% w/w o-cymen-5-ol/ 0.6% w/w zinc chloride/ sodium fluoride dentifrice over a one week period provided a statistically significant benefit in controlling oral malodour for up to 12 hours post-treatment compared to a sodium fluoride control dentifrice. © 2011 FDI World Dental Federation.

  19. Polymeric redox-responsive delivery systems bearing ammonium salts cross-linked via disulfides

    Directory of Open Access Journals (Sweden)

    Christian Dollendorf

    2013-08-01

    Full Text Available A redox-responsive polycationic system was synthesized via copolymerization of N,N-diethylacrylamide (DEAAm and 2-(dimethylaminoethyl methacrylate (DMAEMA. N,N’-bis(4-chlorobutanoylcystamine was used as disulfide-containing cross-linker to form networks by the quaternization of tertiary amine groups. The insoluble cationic hydrogels become soluble by reduction of disulfide to mercaptanes by use of dithiothreitol (DTT, tris(2-carboxyethylphosphine (TCEP or cysteamine, respectively. The soluble polymeric system can be cross-linked again by using oxygen or hydrogen peroxide under basic conditions. The redox-responsive polymer networks can be used for molecular inclusion and controlled release. As an example, phenolphthalein, methylene blue and reactive orange 16 were included into the network. After treatment with DTT a release of the dye could be recognized. Physical properties of the cross-linked materials, e.g., glass transition temperature (Tg, swelling behavior and cloud points (Tc were investigated. Redox-responsive behavior was further analyzed by rheological measurements.

  20. Synthesis and Structural Analysis of Some New Sulfanyl Amino 1,4-Naphthoquinone Derivatives

    Directory of Open Access Journals (Sweden)

    Hatice Yıldırım

    2017-11-01

    Full Text Available In this study, some new sulfanyl substituted amino 1,4-naphthoquinone derivatives which possess two electron donating groups in the amino fragment were synthesized and their structures were analyzed by spectroscopic techniques. First, 2-chloro-3-[(2,4-dimethoxy phenylamino]naphthalene-1,4-dione (3a and 2-chloro-3-[(3,5-dimethoxy phenylamino]naphthalene-1,4-dione (3b were obtained from the reactions of dichloro 1,4-naphthoquinone (1 with 2,4-dimethoxy phenylamine and 3,5-dimethoxy phenylamine. Then the compounds 3a,b were reacted with aliphatic nucleophiles; ethyl-, propyl- and pentyl mercaptan. S-Nucleophiles attacked to the carbon atom of 1,4-naphthoquinone core and displaced with the chlorine atom to create target molecules; 2-aryl amino-3-(ethyl thionaphthalene-1,4-dione (5a,b, 2-aryl amino-3-(propyl thionaphthalene-1,4-dione (5c,d, 2-aryl amino-3-(pentyl thionaphthalene-1,4-dione (5e,f derivatives. The structures of synthesized compounds were proved by utilizing 1D and 2D NMR techniques and also mass spectra and FTIR data.

  1. Theoretical studies on iron surface coating: adsorption of furan derivatives over Fe(n) clusters (n = 1-4).

    Science.gov (United States)

    Montiel, E; Jayanthi, N; Veloz, M A; Pandiyan, T; Cruz, J

    2011-06-01

    In the transition from small molecules to solids, atomic clusters are studied widely not only because they can own unique properties due to the nanosized effect but also because they represent an intermediate stage. A systematic study on the structures and properties of clusters as a function of size could give information on the transition from clusters to bulk and determine at what size a cluster can mimic the bulk solid at least to some extent. The adsorption capability of furan derivatives 2-furfurylamine, 2-furfuryl alcohol and 2-furfuryl mercaptan with different iron-clusters was studied by DFT. The results show that since the compounds possess suitable structural and electronic parameters for the metal adhesion, it is observed that the functional group (NH2, OH and SH) of furan derivatives strongly adsorb over the metal clusters. Moreover, the calculated binding energy supports the existence of a bond between furan derivatives and metal, indicating the transfer of high charge density which in the delocalization region of furan ring to the metal (L(sigma) --> Fe). In the molecular orbital studies by detecting the overlap of HOMO (furan ring and functional group) with LUMO (iron), the binding nature of the compounds is then confirmed.

  2. Efficacy of succimer chelation of mercury at background exposures in toddlers: a randomized trial

    Science.gov (United States)

    Cao, Yang; Chen, Aimin; Jones, Robert L.; Radcliffe, Jerilynn; Dietrich, Kim N.; Caldwell, Kathleen L.; Peddada, Shyamal; Rogan, Walter J.

    2011-01-01

    Objective To examine whether succimer, a mercaptan compound known to reduce blood lead concentration in children, reduces blood mercury concentration. Study Design We used samples from a randomized clinical trial of succimer chelation for lead-exposed children. We measured mercury in pre-treatment samples from 767 children. We also measured mercury in blood samples drawn 1 week after treatment began (N=768) and in a 20% random sample of the children who received the maximum 3 courses of treatment (N=67). A bootstrap-based isotonic regression method was used to compare the trend over time in the difference between the adjusted mean mercury concentrations in the succimer group and the placebo group. Results The adjusted mean organic mercury concentration in the succimer group relative to the placebo group fell from 99% at baseline to 82% after three courses of treatment (p for trend = 0.048), but this resulted from the prevention of the age-related increase in the succimer group. Conclusion Succimer chelation for low level organic mercury exposure in children has limited efficacy. PMID:20889164

  3. Comparative Study on the Characteristics of Weissella cibaria CMU and Probiotic Strains for Oral Care.

    Science.gov (United States)

    Jang, Hye-Jin; Kang, Mi-Sun; Yi, Sung-Hun; Hong, Ji-Young; Hong, Sang-Pil

    2016-12-20

    Probiotics have been demonstrated as a new paradigm to substitute antibiotic treatment for dental caries, gingivitis, and chronic periodontitis. The present work was conducted to compare the characteristics of oral care probiotics: Weissella cibaria CMU (Chonnam Medical University) and four commercial probiotic strains. Survival rates under poor oral conditions, acid production, hydrogen peroxide production, as well as inhibition of biofilm formation, coaggregation, antibacterial activity, and inhibition of volatile sulfur compounds were evaluated. The viability of W. cibaria CMU was not affected by treatment of 100 mg/L lysozyme for 90 min and 1 mM hydrogen peroxide for 6 h. Interestingly, W. cibaria produced less acid and more hydrogen peroxide than the other four probiotics. W. cibaria inhibited biofilm formation by Streptococcus mutans at lower concentrations ( S. mutans /CMU = 8) and efficiently coaggregated with Fusobacterium nucleatum . W. cibaria CMU and two commercial probiotics, including Lactobacillus salivarius and Lactobacillus reuteri , showed high antibacterial activities (>97%) against cariogens ( S. mutans and Streptococcus sobrinus ), and against periodontopathogens ( F. nucleatum and Porphyromonas gingivalis ). All of the lactic acid bacterial strains in this study significantly reduced levels of hydrogen sulfide and methyl mercaptan produced by F. nucleatum and P. gingivalis ( p probiotic.

  4. Qualitative and quantitative analysis of volatile constituents from latrines.

    Science.gov (United States)

    Lin, Jianming; Aoll, Jackline; Niclass, Yvan; Velazco, Maria Inés; Wünsche, Laurent; Pika, Jana; Starkenmann, Christian

    2013-07-16

    More than 2.5 billion people defecate in the open. The increased commitment of private and public organizations to improving this situation is driving the research and development of new technologies for toilets and latrines. Although key technical aspects are considered by researchers when designing new technologies for developing countries, the basic aspect of offending malodors from human waste is often neglected. With the objective of contributing to technical solutions that are acceptable to global consumers, we investigated the chemical composition of latrine malodors sampled in Africa and India. Field latrines in four countries were evaluated olfactively and the odors qualitatively and quantitatively characterized with three analytical techniques. Sulfur compounds including H2S, methyl mercaptan, and dimethyl-mono-(di;tri) sulfide are important in sewage-like odors of pit latrines under anaerobic conditions. Under aerobic conditions, in Nairobi for example, paracresol and indole reached concentrations of 89 and 65 μg/g, respectively, which, along with short chain fatty acids such as butyric acid (13 mg/g) explained the strong rancid, manure and farm yard odor. This work represents the first qualitative and quantitative study of volatile compounds sampled from seven pit latrines in a variety of geographic, technical, and economic contexts in addition to three single stools from India and a pit latrine model system.

  5. Modular-block complex on preparation and processing of oil slurry, spilled and raw petroleum

    International Nuclear Information System (INIS)

    Pak, V.V.

    1999-01-01

    The use of non-serial small petroleum equipment for development of remote and low output petroleum deposit, collection and processing of spilled petroleum is urgent issue. Joint-stock company Montazhengineering developed and mastered production of small modular-block complexes for preparation and processing of petroleum. The complex can include the following modules: preparation of raw petroleum for getting commodity petroleum; petroleum processing installation for getting gas, diesel fuel and black oil; installation for refining of nafta; installation for cleaning petroleum products from mercaptans; installation for getting basic oil; installation for getting bitumen and mastic; installation for processing of spilled petroleum and oil slurry. Each of modules can work separately and in various combinations depending on input and necessary assortment of commodity petroleum. One of urgent ecological problem in Kazakhstan petroleum-processing regions is large number barns with spilled petroleum and oil slurry. Their processing will allow to solve the ecological and economical problems. Processing of spilled petroleum and oil slurry in developed installations it's possible to get commodity petroleum and petroleum products

  6. Effects of Enterococcus faecium SLB 120 on growth performance, blood parameters, relative organ weight, breast muscle meat quality, excreta microbiota shedding, and noxious gas emission in broilers.

    Science.gov (United States)

    Lan, R X; Lee, S I; Kim, I H

    2017-09-01

    This 5-week study was conducted to determine the effects of Enterococcus faecium (SLB 120) on growth performance, blood parameters, relative organ weight, breast muscle meat quality, excreta microbiota shedding, and noxious gas emission in broilers. A total of 816 one-day-old male broilers were allocated to 4 groups with 12 replications (17 broilers/pen) according to body weight (43.2 ± 0.32 g). Dietary treatment groups were: (1) CON, basal diet, (2) T1, CON + 0.05% E. faecium, (3) T2, CON + 0.10% E. faecium, (4) T3, CON + 0.20% E. faecium. From day 1 to 21, dietary E. faecium supplementation showed linear increase (P faecium supplementation showed a linear increase (P faecium supplementation showed a linear increase (P faecium supplementation showed a linear decrease (P faecium supplementation linearly decreased (P faecium improved growth performance, the digestibility of dry matter and nitrogen, the relative weight of bursa of Fabricius, and shifted excreta microbiota by increasing Lactobacillus and decreasing E.coli counts, as well as decreased excreta NH3, H2S, and total mercaptans gas emission. © 2017 Poultry Science Association Inc.

  7. Integration of advanced oxidation processes at mild conditions in wet scrubbers for odourous sulphur compounds treatment.

    Science.gov (United States)

    Vega, Esther; Martin, Maria J; Gonzalez-Olmos, Rafael

    2014-08-01

    The effectiveness of different advanced oxidation processes on the treatment of a multicomponent aqueous solution containing ethyl mercaptan, dimethyl sulphide and dimethyl disulphide (0.5 mg L(-1) of each sulphur compound) was investigated with the objective to assess which one is the most suitable treatment to be coupled in wet scrubbers used in odour treatment facilities. UV/H2O2, Fenton, photo-Fenton and ozone treatments were tested at mild conditions and the oxidation efficiency obtained was compared. The oxidation tests were carried out in magnetically stirred cylindrical quartz reactors using the same molar concentration of oxidants (hydrogen peroxide or ozone). The results show that ozone and photo-Fenton are the most efficient treatments, achieving up to 95% of sulphur compounds oxidation and a mineralisation degree around 70% in 10 min. Furthermore, the total costs of the treatments taking into account the capital and operational costs were also estimated for a comparative purpose. The economic analysis revealed that the Fenton treatment is the most economical option to be integrated in a wet scrubber to remove volatile organic sulphur compounds, as long as there are no space constraints to install the required reactor volume. In the case of reactor volume limitation or retrofitting complexities, the ozone and photo-Fenton treatments should be considered as viable alternatives. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Biofiltration of reduced sulphur compounds and community analysis of sulphur-oxidizing bacteria.

    Science.gov (United States)

    Ramírez, Martín; Fernández, Maikel; Granada, Claudia; Le Borgne, Sylvie; Gómez, José Manuel; Cantero, Domingo

    2011-03-01

    The present work aims to use a two-stage biotrickling filters for simultaneous treatment of hydrogen sulphide (H(2)S), methyl mercaptan (MM), dimethyl sulphide (DMS) and dimethyl disulphide (DMDS). The first biofilter was inoculated with Acidithiobacillus thiooxidans (BAT) and the second one with Thiobacillus thioparus (BTT). For separate feeds of reduced sulphur compounds (RSC), the elimination capacity (EC) order was DMDS>DMS>MM. The EC values were 9.8 g(MM-S)/m(3)/h (BTT; 78% removal efficiency (RE); empty bed residence time (EBRT) 58 s), 36 g(DMDS-S)/m(3)/h (BTT; 94.4% RE; EBRT 76 s) and 57.5 g(H2S-S)/m(3)/h (BAT; 92% RE; EBRT 59 s). For the simultaneous removal of RSC in BTT, an increase in the H(2)S concentration from 23 to 293 ppmv (EBRT of 59 s) inhibited the RE of DMS (97-84% RE), DMDS (86-76% RE) and MM (83-67% RE). In the two-stage biofiltration, the RE did not decrease on increasing the H(2)S concentration from 75 to 432 ppmv. Copyright © 2010 Elsevier Ltd. All rights reserved.

  9. Release of hydrogen sulfide during microwave pyrolysis of sewage sludge: Effect of operating parameters and mechanism.

    Science.gov (United States)

    Zhang, Jun; Zuo, Wei; Tian, Yu; Yin, Linlin; Gong, Zhenlong; Zhang, Jie

    2017-06-05

    The effects of sludge characteristics, pyrolysis temperature, heating rate and catalysts on the release of H 2 S and mechanism of H 2 S formation during sludge pyrolysis were investigated in a microwave heating reactor (MHR). The evolution of sulfur-containing compounds in the pyrolysis chars obtained at temperature range of 400-800°C was characterized by XPS. For a given temperature, the maximum concentration of H 2 S appeared at moisture content of 80%. Compared to the influence of heating rate on the H 2 S yields, pyrolysis temperature and catalyst played a more significant role on the release of H 2 S during microwave pyrolysis process. The H 2 S concentration increased with increasing temperature from 400°C to 800°C while decreased with increasing heating rate. Both the Nickel-based catalyst and Dolomite displayed significant desulfurization effect and Ni-based catalyst exhibited the larger desulfurization capability than that of Dolomite. The organic sulfur compounds accounted for about 60% of the total sulfur in the sludge which was the main reason for the formation of H 2 S. The mechanism analysis indicated that the cleavage reactions of mercaptan and aromatic-S compounds at temperatures below 600°C and the cracking reaction of sulfate above 700°C respectively were responsible for the H 2 S release during sludge pyrolysis. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Development of molecular imprinted nanosensor for determination of tobramycin in pharmaceuticals and foods.

    Science.gov (United States)

    Yola, Mehmet Lütfi; Uzun, Lokman; Özaltın, Nuran; Denizli, Adil

    2014-03-01

    In this study, we developed quartz crystal microbalance (QCM) nanosensor for the real-time detection of tobramycin (TOB). Firstly, the modification of gold surface of QCM chip was performed by self-assembling monolayer formation of allyl mercaptane to introduce polymerizable double bonds on the chip surface. Then, TOB imprinted poly(2-hydroxyethyl methacrylate-methacryloylamidoglutamic acid) [p(HEMA-MAGA)] film was generated on the gold surface. The nonmodified and TOB-imprinted p(HEMA-MAGA) surfaces were characterized by using atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy, ellipsometry and contact angle measurements. The proposed method was validated according to the ICH guideline. The linearity range and the detection limit (S/N=3) were obtained as 1.7×10(-11)-1.5×10(-10) M and 5.7×10(-12) M, respectively. The developed method was applied to pharmaceuticals, and food samples such as chicken egg white and milk extract for the determination of TOB. In addition, association kinetics analysis and isotherm models were applied to the data to explain the adsorption process that took place. © 2013 Elsevier B.V. All rights reserved.

  11. Treatment Efficiency by means of a Nonthermal Plasma Combined with Heterogeneous Catalysis of Odoriferous Volatile Organic Compounds Emissions from the Thermal Drying of Landfill Leachates

    Directory of Open Access Journals (Sweden)

    Daniel Almarcha

    2014-01-01

    Full Text Available The objective of the present work was to assess the odoriferous volatile organic compounds depuration efficiency of an experimental nonthermal plasma coupled to a catalytic system used for odor abatement of real emissions from a leachate thermal drying plant installed in an urban solid waste landfill. VOC screening was performed by means of HRGC-MS analysis of samples taken at the inlet and at the outlet of the nonthermal plasma system. Odor concentration by means of dynamic olfactometry, total organic carbon, mercaptans, NH3, and H2S were also determined in order to assess the performance of the system throughout several days. Three plasma frequencies (100, 150, and 200 Hz and two catalyst temperatures (150°C and 50°C were also tested. Under conditions of maximum capacity of the treatment system, the results show VOC depuration efficiencies around 69%, with average depuration efficiencies between 44 and 95% depending on the chemical family of the substance. Compounds belonging to the following families have been detected in the samples: organic acids, alcohols, ketones, aldehydes, pyrazines, and reduced sulphur compounds, among others. Average total organic carbon removal efficiency was 88%, while NH3 and H2S removal efficiencies were 88% and 87%, respectively, and odor concentration abatement was 78%.

  12. Measurement of gas/water uptake coefficients for trace gases active in the marine environment

    Energy Technology Data Exchange (ETDEWEB)

    Davidovits, P. (Boston Coll., Chestnut Hill, MA (United States). Dept. of Chemistry); Worsnop, D.W.; Zahniser, M.S.; Kolb, C.E. (Aerodyne Research, Inc., Billerica, MA (United States). Center for Chemical and Environmental Physics)

    1992-02-01

    Ocean produced reduced sulfur compounds including dimethylsulfide (DMS), hydrogen sulfide (H{sub 2}S), carbon disulfide (CS{sub 2}), methyl mercaptan (CH{sub 3}CH) and carbonyl sulfide (OCS) deliver a sulfur burden to the atmosphere which is roughly equal to sulfur oxides produced by fossil fuel combustion. These species and their oxidation products dimethyl sulfoxide (DMSO), dimethyl sulfone (DMSO{sub 2}) and methane sulfonic acid (MSA) dominate aerosol and CCN production in clean marine air. Furthermore, oxidation of reduced sulfur species will be strongly influenced by NO{sub x}/O{sub 3} chemistry in marine atmospheres. The multiphase chemical processes for these species must be understood in order to study the evolving role of combustion produced sulfur oxides over the oceans. We have measured the chemical and physical parameters affecting the uptake of reduced sulfur compounds, their oxidation products, ozone, and nitrogen oxides by the ocean's surface, and marine clouds, fogs, and aerosols. These parameters include: gas/surface mass accommodation coefficients; physical and chemically modified (effective) Henry's law constants; and surface and liquid phase reaction constants. These parameters are critical to understanding both the interaction of gaseous trace species with cloud and fog droplets and the deposition of trace gaseous species to dew covered, fresh water and marine surfaces.

  13. Measurement of gas/water uptake coefficients for trace gases active in the marine environment. [Annual report

    Energy Technology Data Exchange (ETDEWEB)

    Davidovits, P. [Boston Coll., Chestnut Hill, MA (United States). Dept. of Chemistry; Worsnop, D.W.; Zahniser, M.S.; Kolb, C.E. [Aerodyne Research, Inc., Billerica, MA (United States). Center for Chemical and Environmental Physics

    1992-02-01

    Ocean produced reduced sulfur compounds including dimethylsulfide (DMS), hydrogen sulfide (H{sub 2}S), carbon disulfide (CS{sub 2}), methyl mercaptan (CH{sub 3}CH) and carbonyl sulfide (OCS) deliver a sulfur burden to the atmosphere which is roughly equal to sulfur oxides produced by fossil fuel combustion. These species and their oxidation products dimethyl sulfoxide (DMSO), dimethyl sulfone (DMSO{sub 2}) and methane sulfonic acid (MSA) dominate aerosol and CCN production in clean marine air. Furthermore, oxidation of reduced sulfur species will be strongly influenced by NO{sub x}/O{sub 3} chemistry in marine atmospheres. The multiphase chemical processes for these species must be understood in order to study the evolving role of combustion produced sulfur oxides over the oceans. We have measured the chemical and physical parameters affecting the uptake of reduced sulfur compounds, their oxidation products, ozone, and nitrogen oxides by the ocean`s surface, and marine clouds, fogs, and aerosols. These parameters include: gas/surface mass accommodation coefficients; physical and chemically modified (effective) Henry`s law constants; and surface and liquid phase reaction constants. These parameters are critical to understanding both the interaction of gaseous trace species with cloud and fog droplets and the deposition of trace gaseous species to dew covered, fresh water and marine surfaces.

  14. ZnO piezoelectric film resonator modified with multi-walled carbon nanotubes/polyethyleneimine bilayer for the detection of trace formaldehyde

    Science.gov (United States)

    Ma, Jilong; Wang, Shaotian; Chen, Da; Wang, Wei; Zhang, Zhen; Song, Shuren; Yu, Wenhua

    2018-01-01

    We fabricated a ZnO piezoelectric film resonator modified with multi-walled carbon nanotubes/polyethyleneimine bilayer as the sensitive layer for the detection of trace gaseous formaldehyde. The resonator consists of a ZnO piezoelectric stack and an SiO2/W Bragg reflector. The multi-walled carbon nanotubes were self-assembled on the resonator surface using the n-octadecyl mercaptan monolayer and further modified with polyethyleneimine. The formaldehyde molecules are absorbed on the multi-walled carbon nanotubes/polyethyleneimine bilayer based on the reversible nucleophilic addition reaction between formaldehyde molecules and the amine functional groups on polyethyleneimine. The high working frequency ( 3.1 GHz) of the resonator provided enough mass sensitivity to probe the ultra-small mass change of the sensitive biolayer. The downshift of resonant frequency was linear with the increase of formaldehyde concentration. The experimental results show that our proposed sensor can yield rapid, sensitive, reversible and repeatable responses to formaldehyde in the concentration range of 50-400 ppb at room temperature. The piezoelectric film resonator is a promising and feasible sensor for the indoor pollution monitoring.

  15. The use of modified tyre derived fuel for compression ignition engines.

    Science.gov (United States)

    Pilusa, T J

    2017-02-01

    This study investigated physical and chemical modification of tyre-derived fuel oil (TDFO) obtained from pyrolysis of waste tyres and rubber products for application as an alternative fuel for compression ignition engines (CIE's). TDFO collected from a local waste tyre treatment facility was refined via a novel "oxidative gas-phase fractional distillation over 13× molecular sieves" to recover the light to medium fractions of the TDFO while oxidising and capturing some sulphur compounds in a gas phase. This was followed by desulphurization and chemical modification to improve cetane number, kinematic viscosity and fuel stability. The resulting fuel was tested in an ADE407T truck engine to compare its performance with petroleum diesel fuel. It was discovered that gas phase oxidative fractional distillation reduces the low boiling point sulphur compounds in TDFO such as mercaptans. Using petroleum diesel fuel as a reference, it was observed that the produced fuel has a lower cetane number, flash point and viscosity. On storage the fuel tends to form fibrous microstructures as a result of auto-oxidation of asphaltenes present in the fuel. Mixtures of alkyl nitrate, vinyl acetate, methacrylic anhydride, methyl-tert butyl ether, n-hexane and n-heptane were used to chemically modify the fuel in accordance with the minimum fuel specifications as per SANS 342. The engine performance tests results did not show any sign of engine ceasing or knocking effect. The power-torque trend was very consistent and compared well with petroleum diesel fuelled engine. The levels of total sulphur are still considerably high compared to other cleaner fuel alternatives derived from zero sulphur sources. Copyright © 2016. Published by Elsevier Ltd.

  16. Reduced sulfur compounds in gas from construction and demolition debris landfills.

    Science.gov (United States)

    Lee, Sue; Xu, Qiyong; Booth, Matthew; Townsend, Timothy G; Chadik, Paul; Bitton, Gabriel

    2006-01-01

    The biological conversion of sulfate from disposed gypsum drywall to hydrogen sulfide (H(2)S) in the anaerobic environment of a landfill results in odor problems and possible health concerns at many disposal facilities. To examine the extent and magnitude of such emissions, landfill gas samples from wells, soil vapor samples from the interface of the waste and cover soil, and ambient air samples, were collected from 10 construction and demolition (C&D) debris landfills in Florida and analyzed for H(2)S and other reduced sulfur compounds (RSC). H(2)S was detected in the well gas and soil vapor at all 10 sites. The concentrations in the ambient air above the surface of the landfill were much lower than those observed in the soil vapor, and no direct correlation was observed between the two sampling locations. Methyl mercaptan and carbonyl sulfide were the most frequently observed other RSC, though they occurred at smaller concentrations than H(2)S. This research confirmed the presence of H(2)S at C&D debris landfills. High concentrations of H(2)S may be a concern for employees working on the landfill site. These results indicate that workers should use proper personal protection at C&D debris landfills when involved in excavation, landfill gas collection, or confined spaces. The results indicate that H(2)S is sufficiently diluted in the atmosphere to not commonly pose acute health impacts for these landfill workers in normal working conditions. H(2)S concentrations were extremely variable with measurements occurring over a very large range (from less than 3 ppbv to 12,000 ppmv in the soil vapor and from less than 3 ppbv to 50 ppmv in ambient air). Possible reasons for the large intra- and inter-site variability observed include waste and soil heterogeneities, impact of weather conditions, and different site management practices.

  17. Volatile metabolites of pathogens: a systematic review.

    Directory of Open Access Journals (Sweden)

    Lieuwe D J Bos

    2013-05-01

    Full Text Available Ideally, invading bacteria are detected as early as possible in critically ill patients: the strain of morbific pathogens is identified rapidly, and antimicrobial sensitivity is known well before the start of new antimicrobial therapy. Bacteria have a distinct metabolism, part of which results in the production of bacteria-specific volatile organic compounds (VOCs, which might be used for diagnostic purposes. Volatile metabolites can be investigated directly in exhaled air, allowing for noninvasive monitoring. The aim of this review is to provide an overview of VOCs produced by the six most abundant and pathogenic bacteria in sepsis, including Staphylococcus aureus, Streptococcus pneumoniae, Enterococcus faecalis, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli. Such VOCs could be used as biological markers in the diagnostic approach of critically ill patients. A systematic review of existing literature revealed 31 articles. All six bacteria of interest produce isopentanol, formaldehyde, methyl mercaptan, and trimethylamine. Since humans do not produce these VOCs, they could serve as biological markers for presence of these pathogens. The following volatile biomarkers were found for identification of specific strains: isovaleric acid and 2-methyl-butanal for Staphylococcus aureus; 1-undecene, 2,4-dimethyl-1-heptane, 2-butanone, 4-methyl-quinazoline, hydrogen cyanide, and methyl thiocyanide for Pseudomonas aeruginosa; and methanol, pentanol, ethyl acetate, and indole for Escherichia coli. Notably, several factors that may effect VOC production were not controlled for, including used culture media, bacterial growth phase, and genomic variation within bacterial strains. In conclusion, VOCs produced by bacteria may serve as biological markers for their presence. Goal-targeted studies should be performed to identify potential sets of volatile biological markers and evaluate the diagnostic accuracy of these markers in critically

  18. Thermodynamic role of glutathione oxidation by peroxide and peroxybicarbonate in the prevention of Alzheimer's disease and cancer.

    Science.gov (United States)

    Galant, Natalie J; Wang, Hui; Lee, DongJin R; Mucsi, Zoltan; Setiadi, David H; Viskolcz, Bela; Csizmadia, Imre G

    2009-08-13

    First principle quantum molecular computations have been carried out at the B3LYP/6-31G(d,p) and G3MP2B3 levels of theory on ethyl mercaptan and diethyl disulfide to study their full conformational space. The consequences of molecular axis chirality for the potential energy hypersurface of diethyl disulfide was fully explored. Thermodynamic functions (U, H, S, and G) have been computed for every conformer of the products as well as the reactants of the redox systems studied. Relative values of the thermodynamic functions were calculated with respect to the reference structures with anti orientation. The energetics of the following Red-Ox reactions Et-SH+HO-OH+HS-Et --> 2H2O+Et-S-S-Et Et-SH+HO-OCOO(-)+HS-Et --> H2O+Et-S-S-Et+HCO3- have been chosen to mimic the biologically important Red-Ox reactions of glutathione G-SH+H2O2+HS-G --> 2H2O+G-S-S-G G-SH+HCO4-+HS-G --> H2O+G-S-S-G+HCO3-. The Red-Ox reaction of Et-SH --> Et-S-S-Et was found to be exothermic by first principle molecular computations and the intramolecular interactions, such as the unusual C-H...H-C noncovalent bondings were studied by Bader's atoms in molecules analysis of the electron density topology. The present paper focuses attention on the thermodynamic aspect of the redox reaction of glutathione. It has been noted previously that on going from a cancerous to a healthy cell, the entropy change is negative, corresponding to information accumulation. Likewise, the dissociation of peptide parallel beta-sheets, that dominate the plaques in Alzheimer's Disease, governs negative entropy change. It may be interesting to note, according to the results obtained in the present paper, a negative entropy change, corresponding to information accumulation.

  19. Spectroelectrochemical study of the [NiFe] hydrogenase from Desulfovibrio vulgaris Miyazaki F in solution and immobilized on biocompatible gold surfaces.

    Science.gov (United States)

    Millo, Diego; Pandelia, Maria-Eirini; Utesch, Tillmann; Wisitruangsakul, Nattawadee; Mroginski, Maria A; Lubitz, Wolfgang; Hildebrandt, Peter; Zebger, Ingo

    2009-11-19

    The catalytic cycle of the anaerobic [NiFe] hydrogenase from Desulfovibrio vulgaris Miyazaki F (DvMF) both in solution and immobilized on an Au electrode was studied by IR spectroscopic and electrochemical methods. IR spectroelectrochemistry in solution at different pH values allows the identification of the various redox-states of the active site and the determination of the midpoint potentials, as well as their acid-base equilibria. The spectroscopic characterization was based on the unique marker bands of the CN and CO stretching modes of the Ni-Fe center and served as reference for the surface-enhanced IR absorption (SEIRA) study of the immobilized enzyme. Using structural models of hydrogenases from DvMF and Desulfovibrio gigas , dipole moment calculations were carried out to guide the immobilization strategy. In view of the high dipole moment of about 1100 D pointing through the negatively charged area surrounding the distal [FeS] cluster, the Au electrode was coated by a self-assembled monolayer of amino-terminated mercaptanes which, due to the positively charged head groups, permit a durable electrostatic binding of the protein. SEIRA spectroscopy revealed a structurally and functionally intact active site as demonstrated by the reversible activation and inactivation under hydrogen and argon, respectively. Cyclic voltammetry on the immobilized enzyme demonstrate a reversible anaerobic inactivation upon changing the applied potential. The "switch" potential (E(switch)) associated with the reductive reactivation was determined to be -33 mV (vs normal hydrogen electrode). However, the catalytic current decreased on the time scale of hours during continuous cycling. SEIRA experiments demonstrate that the loss of catalytic activity is not due to protein desorption but is rather related to a slow degradation of the active site, possibly initiated by the attack of reactive species electrochemically generated from residual traces of oxygen in solution.

  20. Inactivation of microorganisms by UV-treatment of must and wine

    Directory of Open Access Journals (Sweden)

    Durner Dominik

    2017-01-01

    Full Text Available The objective was to investigate the applicability of UV-C technology to inactivate yeasts and bacteria in must and wine. Experiments were carried out in vintage 2016 with Riesling musts of different quality containing their natural microflora. Yeasts were tested more resistant to UV-C energy than bacteria. Saccharomyces cerevisiae showed higher tolerance against UV-C irradiation than Hanseniaspora uvarum facilitating new opportunities to control spontaneous fermentations. However, inactivation efficacy was strongly dependent on turbidity of musts and the initial degree of contamination suggesting a shadowing effect of individual germs. Compared with thermal pasteurization, UV-C treatment of must with 1 kJ/L showed similar effects in germ-reduction. While thermal pasteurization significantly decreased aroma precursors in musts, UV-C treatment did not change concentrations of glycosidically-bound C6-alcohols, monoterpenes and C13-norisoprenoids as shown by GC-MS analysis. Applying UV-C technology in wines, it was possible to irreversibly stop ongoing alcoholic fermentation indicating that UV-C treatment is capable to replace SO2 addition to produce wines with residual sugar. Besides inactivation power, UV-C is known for its ability to form powerful off-flavours such as methional or methanethiol. Sensory analysis revealed that the application of UV-C at doses < 2 kJ/L in must is uncritical. However, applying UV-C after alcoholic fermentation can result in rising concentrations of mercaptans already at doses < 1 kJ/L. In this context, compounds such as caftaric acid, riboflavin and dissolved oxygen are thought to positively contribute to the UV-induced formation of off-flavours in wine.

  1. Characterization of industrial waste from a natural gas distribution company and management strategies: a case study of the East Azerbaijan Gas Company (Iran).

    Science.gov (United States)

    Taghipour, Hassan; Aslhashemi, Ahmad; Assadi, Mohammad; Khodaei, Firoz; Mardangahi, Baharak; Mosaferi, Mohammad; Roshani, Babak

    2012-10-01

    Although a fundamental prerequisite for the successful implementation of any waste management plan is the availability of sufficient and accurate data, there are few available studies regarding the characterization and management of gas distribution company waste (GDCW). This study aimed to characterize the industrial waste generated by the East Azerbaijan Gas Distribution Company (EAGDC) and to present environmental management strategies. The EAGDC serves 57 cities and 821 villages with a total population of more than 2.5 million as well as numerous industrial units. The methodology of this study was based on a checklist of data collected from each zone of the company, site visits (observation), and quantity and quality analysis according to the formal data available from different zones. The results indicate that more than 35 different kinds of industrial solid waste are generated in different industrial installations. The most important types of generated waste include empty barrels (including mercaptans, diesel fuel, deionized waters and oil), faulty gas meters and regulators, a variety of industrial oils, sleeves, filter elements and faulty pipes, valves and fittings. The results indicated that, currently, GDCW is generally handled and disposed of with domestic waste, deposited in companies' installation yards and stores or, sometimes, recycled through non-scientific approaches that can create health risks to the public and the environment, even though most of the GDCW was determined to be recyclable or reusable materials. This study concludes that gas distribution companies must pay more attention to source reduction, recycling and reusing of waste to preserve natural resources, landfill space and the environment.

  2. The sulfur dilemma: Are there biosignatures on Europa's icy and patchy surface?

    International Nuclear Information System (INIS)

    Chela-Flores, J.

    2006-12-01

    We discuss whether sulphur traces on Jupiter's moon Europa could be of biogenic origin. The compounds detected by the Galileo mission have been conjectured to be endogenic, most likely of cryovolcanic origin, due to their non-uniform distribution in patches. The Galileo space probe first detected the sulphur compounds, as well as revealing that this moon almost certainly has a volcanically heated and potentially habitable ocean hiding beneath a surface layer of ice. In planning future exploration of Europa there are options for sorting out the source of the surficial sulphur. For instance, one possibility is searching for the sulphur source in the context of the study of the Europa Microprobe In Situ Explorer (EMPIE), which has been framed within the Jovian Minisat Explorer Technology Reference Study (ESA). It is conceivable that sulphur may have come from the nearby moon Io, where sulphur and other volcanic elements are abundant. Secondly, volcanic eruptions in Europa's seafloor may have brought sulphur to the surface. Can waste products rising from bacterial colonies beneath the icy surface be a third alternative significant factor in the sulphur patches on the Europan surface? Provided that microorganisms on Europa have the same biochemical pathways as those on Earth, over geologic time it is possible that autochthonous microbes can add substantially to the sulphur deposits on the surface of Europa. We discuss possible interpretations of the non-water-ice elements (especially the sulphur compound mercaptan) in the context of the studies for future missions. To achieve reliable biosignatures it seems essential to go back to Europa. Our work highlights the type of biogenic signatures that can be searched for when probing Europa's icy and patchy surface. (author)

  3. Kinetic modeling of the thermal evolution of crude oils in sedimentary basins; Modelisation cinetique de l'evolution thermique des petroles dans les gisements

    Energy Technology Data Exchange (ETDEWEB)

    Bounaceur, R.

    2001-01-15

    The aim of this work is to obtain a better understanding of the reactions involved in the thermal cracking of crude oil in sedimentary basins, and to study its kinetics as a function of temperature and pressure. We study the kinetics of pyrolysis of alkanes at low temperature, high pressure and high conversion and we propose three methods of reduction of the corresponding mechanisms. Several compounds having an inhibiting or accelerating effect on the rate of decomposition of alkanes were also studied. This research led to the construction of a general kinetic model of 5200 elementary steps representing the pyrolysis of a complex mixture of 52 molecules belonging to various chemical families: 30 linear alkanes (from CH{sub 4} to C{sub 30}H{sub 62}), 10 branched-chain alkanes (including pristane and phytane), 2 naphthenes (propyl-cyclo-pentane and propyl-cyclohexane), tetralin, 1-methyl-indan, 4 aromatics (benzene, toluene, butyl-benzene and decyl-benzene), 3 hetero-atomic compounds (a disulfide, a mercaptan and H{sub 2}S). This model is compared to experimental data coming from the pyrolysis of two oils: one from the North Sea and the other from Pematang. The results obtained show a good agreement between the experimental and simulated values. Then, we simulated the cracking of these two oils by using the following burial scenario: initial temperature of 160 degrees, 50 m per million years (ma) in a constant geothermal gradient of 30 degrees C/km, implying a heating rate of 1.5 degrees C/ma. Under these conditions, our model shows that these two oils start to crack only towards 210-220 degrees C and that their time of half-life corresponds to a temperature around 230-240 degrees C. The model also makes it possible to simulate the evolution of geochemical parameters such as the GOR, the API degree... (author)

  4. Studies on thio-substituted polyurethane foam (T-PUF) as a new efficient separation medium for the removal of inorganic/organic mercury from industrial effluents and solid wastes.

    Science.gov (United States)

    Anjaneyulu, Y; Marayya, R; Rao, T H

    1993-01-01

    Novel thio-substituted flexible polyurethane foam (T-PUF) was synthesised by addition polymerisation of mercaptan with the precursors of an open-cell polyurethane foam, which can be used as a highly selective sorbent for inorganic and organic mercury from complex matrices. The percentage extraction of inorganic mercury was studied at different flow-rates, over a wide pH range at different concentrations ranging from 1 ppm, to 100 ppm. The break-through capacity and total capacity of unmodified and thio-foams were determined for inorganic and organic mercurials. The absorption efficiency of thio-foam was far superior to other sorbent media, such as activated carbon, polymeric ion-exchange resins and reagent-loaded polyurethane foams. It was observed that even at the 1000 ppm level, divalent ions like Cu, Mg, Ca, Zn do not appreciably influence the per cent extraction of inorganic mercury at the 10 ppm level. These matrix levels are the most concentrated ones which are likely to occur, both in local sewage and effluent waters. Further, the efficiency of this foam was sufficiently high at 10-100 ppm levels of Hg, even from 5-10 litres of effluent volumes using 50 g of thio-foam packed into different columns in series. Thio-foams were found to possess excellent abilities to remove and recover mercury even at low levels from industrial effluents and brine mud of chlor-alkali industry after pre-acid extraction. This makes it a highly efficient sorbent for possible application in effluent treatment. Model schemes for the removal and recovery of mercury from industrial effluents and municipal sewage (100-1000 litre) by a dynamic method are proposed and the costs incurred in a full-scale application method are indicated to show that the use of thio-foam could be commercially attractive.

  5. Protective Behaviour of Citizens to Transport Accidents Involving Hazardous Materials: A Discrete Choice Experiment Applied to Populated Areas nearby Waterways.

    Science.gov (United States)

    de Bekker-Grob, Esther W; Bergstra, Arnold D; Bliemer, Michiel C J; Trijssenaar-Buhre, Inge J M; Burdorf, Alex

    2015-01-01

    To improve the information for and preparation of citizens at risk to hazardous material transport accidents, a first important step is to determine how different characteristics of hazardous material transport accidents will influence citizens' protective behaviour. However, quantitative studies investigating citizens' protective behaviour in case of hazardous material transport accidents are scarce. A discrete choice experiment was conducted among subjects (19-64 years) living in the direct vicinity of a large waterway. Scenarios were described by three transport accident characteristics: odour perception, smoke/vapour perception, and the proportion of people in the environment that were leaving at their own discretion. Subjects were asked to consider each scenario as realistic and to choose the alternative that was most appealing to them: staying, seeking shelter, or escaping. A panel error component model was used to quantify how different transport accident characteristics influenced subjects' protective behaviour. The response was 44% (881/1,994). The predicted probability that a subject would stay ranged from 1% in case of a severe looking accident till 62% in case of a mild looking accident. All three transport accident characteristics proved to influence protective behaviour. Particularly a perception of strong ammonia or mercaptan odours and visible smoke/vapour close to citizens had the strongest positive influence on escaping. In general, 'escaping' was more preferred than 'seeking shelter', although stated preference heterogeneity among subjects for these protective behaviour options was substantial. Males were less willing to seek shelter than females, whereas elderly people were more willing to escape than younger people. Various characteristics of transport accident involving hazardous materials influence subjects' protective behaviour. The preference heterogeneity shows that information needs to be targeted differently depending on gender and age

  6. Halitosis among racially diverse populations: an update.

    Science.gov (United States)

    Rayman, S; Almas, K

    2008-02-01

    The aim of this paper is to highlight the cultural perceptions of halitosis to dental professionals. Halitosis (oral malodour or bad breath) is caused mainly by tongue coating and periodontal disease. Bacterial metabolism of amino acids leads to metabolites including many compounds, such as indole, skatole and volatile sulphur compounds (VSC), hydrogen sulphide, methyl mercaptan and dimethyl sulphide. They are claimed to be the main aetiological agents for halitosis. Gastrointestinal diseases are also generally believed to cause halitosis. In general, physicians and dentists are poorly informed about the causes and treatments for halitosis. The paper reviews the prevalence and distribution of halitosis, oral malodour, its aetiology, concepts of general and oral health and diseases and their perception among racially diverse population. Eating, smoking and drinking habits and understanding of halitosis as a social norm among different people has been highlighted. The treatment options have also been presented very briefly. A brief discussion about general importance within existing healthcare services has been highlighted. Oral malodour may rank only behind dental caries and periodontal disease as the cause of patient's visits to the dentist. It is a public social health problem. The perception of halitosis is different in culturally diverse populations. So the dental professionals should be aware of the cultural perceptions of halitosis among racially and culturally diverse populations. There is a need to integrate the cultural awareness and knowledge about halitosis among the dental professional for better understanding of halitosis to treat patients with the social dilemma of halitosis to improve the quality of life and well-being of individuals with the problem. It is concluded that dental professionals (especially dental hygienists) should be prepared to practice in a culturally diverse environment in a sensitive and appropriate manner, to deliver optimal oral

  7. Changes in salivary microbiota increase volatile sulfur compounds production in healthy male subjects with academic-related chronic stress.

    Directory of Open Access Journals (Sweden)

    Bruno Dias Nani

    Full Text Available To investigate the associations among salivary bacteria, oral emanations of volatile sulfur compounds, and academic-related chronic stress in healthy male subjects.Seventy-eight healthy male undergraduate dental students were classified as stressed or not by evaluation of burnout, a syndrome attributed to academic-related chronic stress. This evaluation was carried out using the Maslach Burnout Inventory-Student Survey questionnaire. Oral emanations of hydrogen sulfide, methyl mercaptan, and dimethyl sulfide were measured using an Oral Chroma™ portable gas chromatograph. The amounts in saliva of total bacteria and seven bacteria associated with halitosis were quantified by qPCR. The in vitro production of H2S by S. moorei and/or F. nucleatum was also measured with the Oral Chroma™ instrument.The stressed students group showed increased oral emanations of hydrogen sulfide and dimethyl sulfide, together with higher salivary Solobacterium moorei levels (p < 0.05, Mann Whitney test. There were moderate positive correlations between the following pairs of variables: Fusobacterium nucleatum and S. moorei; F. nucleatum and hydrogen sulfide; Tannerella forsythia and F. nucleatum; T. forsythia and S. moorei. These correlations only occurred for the stressed group (p < 0.05, Spearman correlation. The in vitro experiment demonstrated that S. moorei increased H2S production by F. nucleatum (p < 0.05, ANOVA and Tukey's test.The increased amount of S. moorei in saliva, and its coexistence with F. nucleatum and T. forsythia, seemed to be responsible for increased oral hydrogen sulfide in the healthy male stressed subjects.

  8. A novel assessment of odor sources using instrumental analysis combined with resident monitoring records for an industrial area in Korea

    Science.gov (United States)

    Lee, Hyung-Don; Jeon, Soo-Bin; Choi, Won-Joon; Lee, Sang-Sup; Lee, Min-Ho; Oh, Kwang-Joong

    2013-08-01

    The residents living nearby the Sa-sang industrial area (SSIA) continuously were damaged by odorous pollution since 1990s. We determined the concentrations of reduced sulfur compounds (RSCs) [hydrogen sulfide (H2S), methyl mercaptan (CH3SH), dimethyl sulfide (DMS), and dimethyl disulfide (DMDS)], nitrogenous compounds (NCs) [ammonia (NH3) and trimethylamine (TMA)], and carbonyl compounds (CCs) [acetaldehyde and butyraldehyde] by instrumental analysis in the SSIA in Busan, Korea from Jun to Nov, 2011. We determined odor intensity (OI) based on the concentrations of the odorants and resident monitoring records (RMR). The mean concentration of H2S was 10-times higher than NCs, CCs and the other RSC. The contribution from RSCs to the OI was over 50% at all sites excluding the A-5 (chemical production) site. In particular, A-4 (food production) site showed more than 8-times higher the sum of odor activity value (SOAV) than the other sites. This suggested that the A-4 site was the most malodorous area in the SSIA. From the RMR analysis, the annoyance degree (OI ≥ 2) was 51.9% in the industrial area. The 'Rotten' smell arising from the RSCs showed the highest frequency (25.3%) while 'Burned' and 'Other' were more frequent than 'Rotten' in the residential area. The correlation between odor index calculated by instrumental analysis and OI from the RMR was analyzed. The Pearson correlation coefficient (r) of the SOAV was the highest at 0.720 (P food production causes significant annoyance in the SSIA. We also confirm RMR data can be used effectively to evaluate the characteristic of odorants emitted from the SSIA.

  9. Efficacy and role of inulin in mitigation of enteric sulfur-containing odor in pigs.

    Science.gov (United States)

    Deng, Yuan-Fan; Liu, Yuan-Yuan; Zhang, Yi-Tao; Wang, Yan; Liang, Juan-Boo; Tufarelli, Vincenzo; Laudadio, Vito; Liao, Xin-Di

    2017-06-01

    The efficacy and role of inulin in the mitigation of enteric sulfur-containing odor gases hydrogen sulfide (H 2 S) and methyl mercaptan (CH 3 SH) in pigs were examined in this study. Twelve Duroc × Landrace × Yorkshire male finisher pigs (60.7 ± 1.9 kg), housed individually in open-circuit respiration chambers, were randomly assigned to two dietary groups, namely basal diet (control) and basal diet supplemented with 1% (w/w) inulin. At the end of the 45 day experiment, pigs were slaughtered and volatile fatty acid (VFA) concentration, sulfate radical (SO 4 2 - ) concentration, population of sulfate-reducing bacteria (SRB) and expression of methionine gamma-lyase (MGL) gene were determined in contents from the caecum, colon (two segments) and rectum. Metabonomic analysis was used to compare differences in biochemical composition, and the Illumina MiSeq procedure to investigate differences in bacterial components, in the different parts of the large intestine between inulin-supplemented and inulin-free (control) groups. Inulin decreased (P inulin treatment, whereas valerate concentration and MGL mRNA expression decreased (P inulin-supplemented pigs, suggesting that inulin mitigates H 2 S generation from the SO 4 2 - reduction pathway by reducing the growth of SRB. The results showed that inulin mitigates CH 3 SH generation via three methionine degradation metabolic pathways and H 2 S generation from two cysteine degradation metabolic pathways, thus resulting in increased synthesis of these two sulfur-containing amino acids in the pig large intestine. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  10. Characterisation and cleaning of biogas from sewage sludge for biomethane production.

    Science.gov (United States)

    Paolini, Valerio; Petracchini, Francesco; Carnevale, Monica; Gallucci, Francesco; Perilli, Mattia; Esposito, Giulio; Segreto, Marco; Occulti, Leandro Galanti; Scaglione, Davide; Ianniello, Antonietta; Frattoni, Massimiliano

    2018-03-30

    This study investigates the conversion of sewage sludge from wastewater treatment plants (WWTP) into biomethane for automotive fuel or grid injection. A prototype plant was monitored in Northern Italy, based on vacuum swing adsorption (VSA) on synthetic zeolite 13×: this biogas upgrading method is similar to pressure swing adsorption (PSA) and commonly used for other kinds of biomass. Measurements of biogas inlet, biomethane outlet and off-gas were performed including CH 4 , CO 2 , CO, H 2 , O 2 , N 2 , HCl, HF, NH 3 , H 2 S and volatile organic compounds (VOCs). Critical levels were observed in the biogas for of H 2 S and HCl, whose concentrations were 1570 and 26.8 mg m -3 , respectively. On the other hand, the concentration of halogenated VOCs (including tetrachloroethylene and traces of perfluoroalkilated substances, PFAS) and mercaptans were relatively low. A simultaneous and reversible adsorption on 13× zeolite was achieved for H 2 S and CO 2 , and carbon filters played a minor role in desulfurisation. The presence of HCl is due to clarifying agents, and its removal is necessary in order to meet the required biomethane characteristics: an additional carbon-supported basic adsorbent was successfully used to remove this contaminant. This study also highlights the interference of CO 2 towards HCl if sampling is performed in compliance with the new EU standard for biomethane. High total volatile silicon (TVS) was confirmed in sewage sludge biogas, with a major contribution of siloxane D5: the suitability of this compound as an indicator of total siloxanes is discussed. Results demonstrate that volatile methyl siloxanes (VMS) do not represent a critical issue for the VSA upgrading methodology. Copyright © 2018 Elsevier Ltd. All rights reserved.

  11. Short-term gas dispersion in idealised urban canopy in street parallel with flow direction

    Directory of Open Access Journals (Sweden)

    Chaloupecká Hana

    2016-01-01

    Full Text Available Chemical attacks (e.g. Syria 2014-15 chlorine, 2013 sarine or Iraq 2006-7 chlorine as well as chemical plant disasters (e.g. Spain 2015 nitric oxide, ferric chloride; Texas 2014 methyl mercaptan threaten mankind. In these crisis situations, gas clouds are released. Dispersion of gas clouds is the issue of interest investigated in this paper. The paper describes wind tunnel experiments of dispersion from ground level point gas source. The source is situated in a model of an idealised urban canopy. The short duration releases of passive contaminant ethane are created by an electromagnetic valve. The gas cloud concentrations are measured in individual places at the height of the human breathing zone within a street parallel with flow direction by Fast-response Ionisation Detector. The simulations of the gas release for each measurement position are repeated many times under the same experimental set up to obtain representative datasets. These datasets are analysed to compute puff characteristics (arrival, leaving time and duration. The results indicate that the mean value of the dimensionless arrival time can be described as a growing linear function of the dimensionless coordinate in the street parallel with flow direction where the gas source is situated. The same might be stated about the dimensionless leaving time as well as the dimensionless duration, however these fits are worse. Utilising a linear function, we might also estimate some other statistical characteristics from datasets than the datasets means (medians, trimeans. The datasets of the dimensionless arrival time, the dimensionless leaving time and the dimensionless duration can be fitted by the generalized extreme value distribution (GEV in all sampling positions except one.

  12. Cancer chemoprevention by targeting the epigenome.

    Science.gov (United States)

    Huang, Joseph; Plass, Christoph; Gerhauser, Clarissa

    2011-12-01

    The term "epigenetics" refers to modifications in gene expression caused by heritable, but potentially reversible, changes in DNA methylation and chromatin structure. Given the fact that epigenetic modifications occur early in carcinogenesis and represent potentially initiating events in cancer development, they have been identified as promising new targets for prevention strategies. The present review will give a comprehensive overview of the current literature on chemopreventive agents and their influence on major epigenetic mechanisms, that is DNA methylation, histone acetylation and methylation, and microRNAs, both in vitro and in rodent and human studies, taking into consideration specific mechanisms of action, target sites, concentrations, methods used for analysis, and outcome. Chemopreventive agents with reported mechanisms targeting the epigenome include micronutrients (folate, selenium, retinoic acid, Vit. E), butyrate, polyphenols (from green tea, apples, coffee, and other dietary sources), genistein and soy isoflavones, parthenolide, curcumin, ellagitannin, indol-3-carbinol (I3C) and diindolylmethane (DIM), mahanine, nordihydroguaiaretic acid (NDGA), lycopene, sulfur-containing compounds from Allium and cruciferous vegetables (sulforaphane, phenylethyl isothiocyanate (PEITC), phenylhexyl isothiocyanate (PHI), diallyldisulfide (DADS), allyl mercaptan (AM)), antibiotics (mithramycin A, apicidin), pharmacological agents (celecoxib, DFMO, 5-aza-2'-deoxycytidine and zebularine), compounds affecting sirtuin activity (resveratrol, dihydrocoumarin, cambinol), inhibitors of histone acetyl transferases (anacardic acid, garcinol, ursodeoxycholic acid), and relatively unexplored modulators of histone lysine methylation (chaetocin, polyamine analogues, n-3 polyunsaturated fatty acids). Their effects on global DNA methylation, tumor suppressor genes silenced by promoter methylation, histone modifications, and miRNAs deregulated during carcinogenesis have potential

  13. The effects of dentifrice systems on oral malodor.

    Science.gov (United States)

    Brunette, D M; Proskin, H M; Nelson, B J

    1998-01-01

    Chronic oral malodor is a serious concern for about one-fifth of the North American population, and a field of emerging research interest. The present three studies, one involving gas chromatography and two employing odor judge assessment, examined the efficacy of baking soda and other toothpastes in reducing breath odor. The most common cause of oral malodor is elevated levels of volatile sulfur compounds (VSC's), primarily hydrogen sulfide (H2S) and methyl mercaptan (CH3SH), in the breath. Gas chromatography, an accurate means of measuring breath VSC, was employed to evaluate the breath levels of VSC in 11 men after brushing with baking soda-containing dentifrices with or without the addition of Zn++. Dentifrices with either Zn++ or a concentration of baking soda 20% or greater significantly reduced VSC levels. The addition of Zn++ to baking soda dentifrices enhanced the anti-odor effects. In the first organoleptic study, dentifrices containing 20% baking soda and 30% baking soda demonstrated significantly greater ability to reduce breath odor than a standard sodium fluoride/silica dentifrice. The subjects' baseline mouth odor evaluations, initially rated as strong, declined after brushing with the baking soda toothpastes to a barely detectable level at one hour, then rising to a faint level at two hours and moderate levels at three hours. In the second organoleptic study, a dentifrice containing 65% baking soda demonstrated significantly greater ability to reduce breath odor than a standard sodium fluoride/silica tartar control dentifrice, but did not differ significantly from a standard dentifrice containing 0.76% sodium monofluorophosphate in a dicalcium phosphate dihydrate base. The results of these studies indicate that dentifrices containing 20% or more baking soda can confer a significant odor-reducing benefit for time periods up to three hours.

  14. Formation and Atmosphere of Complex Organic Molecules of the HH 212 Protostellar Disk

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chin-Fei; Ho, Paul T. P.; Hirano, Naomi; Shang, Hsien [Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 106, Taiwan (China); Li, Zhi-Yun [Astronomy Department, University of Virginia, Charlottesville, VA 22904 (United States); Zhang, Qizhou, E-mail: cflee@asiaa.sinica.edu.tw [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2017-07-01

    HH 212 is a nearby (400 pc) Class 0 protostellar system recently found to host a “hamburger”-shaped dusty disk with a radius of ∼60 au, deeply embedded in an infalling-rotating flattened envelope. We have spatially resolved this envelope-disk system with the Atacama Large Millimeter/submillimeter Array at up to ∼16 au (0.″04) resolution. The envelope is detected in HCO{sup +} J = 4–3 down to the dusty disk. Complex organic molecules (COMs) and doubly deuterated formaldehyde (D{sub 2}CO) are detected above and below the dusty disk within ∼40 au of the central protostar. The COMs are methanol (CH{sub 3}OH), deuterated methanol (CH{sub 2}DOH), methyl mercaptan (CH{sub 3}SH), and formamide (NH{sub 2}CHO, a prebiotic precursor). We have modeled the gas kinematics in HCO{sup +} and COMs and found a centrifugal barrier (CB) at a radius of ∼44 au, within which a Keplerian rotating disk is formed. This indicates that HCO{sup +} traces the infalling-rotating envelope down to the CB and COMs trace the atmosphere of a Keplerian rotating disk within the CB. The COMs are spatially resolved for the first time, both radially and vertically, in the atmosphere of a disk in the earliest, Class 0 phase of star formation. Our spatially resolved observations of COMs favor their formation in the disk rather than a rapidly infalling (warm) inner envelope. The abundances and spatial distributions of the COMs provide strong constraints on models of their formation and transport in low-mass star formation.

  15. Effect of naphtha diluent on greenhouse gases and reduced sulfur compounds emissions from oil sands tailings.

    Science.gov (United States)

    Gee, Kathleen F; Poon, Ho Yin; Hashisho, Zaher; Ulrich, Ania C

    2017-11-15

    The long-term storage of oil sands tailings has resulted in the evolution of greenhouse gases (CH 4 and CO 2 ) as a result of residual organics biodegradation. Recent studies have identified black, sulfidic zones below the tailings-water interface, which may be producing toxic sulfur-containing gases. An anaerobic mesocosm study was conducted over an 11-week period to characterize the evolution of CH 4 , CO 2 and reduced sulfur compounds (RSCs) (including H 2 S) in tailings as it relates to naphtha-containing diluent concentrations (0.2, 0.8, and 1.5% w/v) and microbial activity. Our results showed that RSCs were produced first at 0.12μmol°RSCs/mL MFT (1.5% w/v diluent treatment). RSCs contribution (from highest to lowest) was H 2 S and 2-methylthiophene>2.5-dimethylthiophene>3-methylthiophene>thiofuran>butyl mercaptan>carbonyl sulfide, where H 2 S and 2-methylthiophene contributed 81% of the gas produced. CH 4 and CO 2 production occurred after week 5 at 40.7μmolCH 4 /mL MFT and 5.9μmolCO 2 /mL MFT (1.5% w/v diluent treatment). The amount of H 2 S and CH 4 generated is correlated to the amount of diluent present and to microbial activity as shown by corresponding increases in sulfate-reducers' Dissimilatory sulfite reductase (DsrAB) gene and methanogens' methyl-coenzyme M reductase (MCR) gene. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Utilização de NBR modificada com grupos 2-oxazolina em misturas de NBR/EVA Utilization of 2-oxazoline modified NBR in NBR/EVA blends

    Directory of Open Access Journals (Sweden)

    Mauricio S. M. Almeida

    2003-06-01

    Full Text Available Misturas envolvendo borracha nitrílica e copolímeros de etileno-acetato de vinila na proporção 70:30 % em peso, foram preparadas na presença de borracha nitrílica funcionalizada com 2-oxazolina isoladamente ou combinada com EVA funcionalizado com grupos hidroxila, carboxila ou mercaptana. A reação entre os grupos funcionais foi verificada por análise de FTIR da fração insolúvel de amostras não vulcanizadas e pelo decréscimo nos valores de tan delta nos ensaios dinâmico-mecânicos. A utilização desses copolímeros funcionalizados não influenciou significativamente as propriedades mecânicas, provavelmente devido à proporção da mistura utilizada (rica em NBR o que facilita a localização da NBR funcionalizada no interior da fase elastomérica.Nitrile rubber/ethylene-vinyl acetate copolymer (NBR/EVA blends with ratio of 70/30 wt% were prepared in the presence of functionalized NBR with 2-oxazoline groups. This functionalized copolymer was employed alone or in combination with EVA copolymer functionalized with hydroxyl, carboxyl or mercaptan groups. The reaction between the functional groups was confirmed by FTIR analysis of the unvulcanized samples insoluble fraction, and by the decrease in the tan delta values. The mechanical properties were not substantially affected by the presence of these functionalized copolymers, probably due to the proportion of blend composition (with high amount of NBR, thus forcing the location of functionalized NBR inside the elastomer phase.

  17. Calibration transfer between electronic nose systems for rapid In situ measurement of pulp and paper industry emissions

    International Nuclear Information System (INIS)

    Deshmukh, Sharvari; Kamde, Kalyani; Jana, Arun; Korde, Sanjivani; Bandyopadhyay, Rajib; Sankar, Ravi; Bhattacharyya, Nabarun; Pandey, R.A.

    2014-01-01

    Highlights: • E-nose developed for obnoxious emissions measurement at pulp and paper industrial site. • ANN model developed for prediction of (CH 3 ) 2 S, (CH 3 ) 2 S 2 , CH 3 SH and H 2 S concentration. • Calibration transfer methodology developed for transfer between two e-nose instruments. • Box–Behnken design and robust regression used for calibration transfer. • Results show effective transfer of training model from one e-nose system to other. - Abstract: Electronic nose systems when deployed in network mesh can effectively provide a low budget and onsite solution for the industrial obnoxious gaseous measurement. For accurate and identical prediction capability by all the electronic nose systems, a reliable calibration transfer model needs to be implemented in order to overcome the inherent sensor array variability. In this work, robust regression (RR) is used for calibration transfer between two electronic nose systems using a Box–Behnken (BB) design. Out of the two electronic nose systems, one was trained using industrial gas samples by four artificial neural network models, for the measurement of obnoxious odours emitted from pulp and paper industries. The emissions constitute mainly of hydrogen sulphide (H 2 S), methyl mercaptan (MM), dimethyl sulphide (DMS) and dimethyl disulphide (DMDS) in different proportions. A Box–Behnken design consisting of 27 experiment sets based on synthetic gas combinations of H 2 S, MM, DMS and DMDS, were conducted for calibration transfer between two identical electronic nose systems. Identical sensors on both the systems were mapped and the prediction models developed using ANN were then transferred to the second system using BB–RR methodology. The results showed successful transmission of prediction models developed for one system to other system, with the mean absolute error between the actual and predicted concentration of analytes in mg L −1 after calibration transfer (on second system) being 0.076, 0

  18. Dynamic olfactometry and GC–TOFMS to monitor the efficiency of an industrial biofilter

    Energy Technology Data Exchange (ETDEWEB)

    Gutiérrez, M.C.; Martín, M.A. [University of Cordoba, Department of Inorganic Chemical and Chemical Engineering, Campus Universitario de Rabanales, Carretera N-IV, km 396, Edificio Marie Curie, 14071 Córdoba (Spain); Pagans, E.; Vera, L. [Odournet SL, Parc de Recerca UAB, Edificio Eureka, Espacio P2M2, 08193, Bellaterra, Cerdanyola del Vallès, Barcelona (Spain); García-Olmo, J. [NIR/MIR Spectroscopy Unit, Central Service for Research Support (SCAI), University of Cordoba, Campus de Rabanales, 14071 Cordoba (Spain); Chica, A.F., E-mail: afchica@uco.es [University of Cordoba, Department of Inorganic Chemical and Chemical Engineering, Campus Universitario de Rabanales, Carretera N-IV, km 396, Edificio Marie Curie, 14071 Córdoba (Spain)

    2015-04-15

    Biofiltration is the most widely used technique for eliminating odours in waste treatment plants. Volatile organic compounds (VOCs) are among the odorous compounds emitted by waste management plants, and serve as variables to measure odour emissions depending on the type of aeration process used. In this work, we assess the performance of an industrial-scale biofilter where composting is the main source of VOCs and odour emissions. Dynamic olfactometry is the sensorial technique used to determine odour concentration, while gas chromatography–time of flight-mass spectrometry (GC–TOFMS) is used to perform the chemical characterization. This work examines a total of 82 compounds belonging to 15 odorous families of VOCs, particularly mercaptans, sulphur-containing compounds, alcohols and terpenes, among others. Principal component analysis (PCA) is used to assess the influence of each of these families of VOCs on the total variance of the measure with regard to both the input and output flow of the biofilter. Finally, partial least-squares (PLS) regression is used to estimate the odour concentration in each of the samples taken at the inlet and outlet of the biofilter in each of the samples based on the chemical information provided by chromatographic analysis. The study shows that there is an adequate correlation (r = 0.9751) between real and estimated odour concentrations, both of which are expressed in European odour units per cubic metre (ou{sub E}·m{sup −3}). - Highlights: • Odour and VOC removal by industrial biofilter was evaluated. • Dynamic olfactometry and GC-TOF MS were the techniques used. • The compost aeration mode was considered in this study. • The influence of 15 VOC families on sample variance was demonstrated by PCA. • Odour concentration was predicted from selected chromatographic information by PLS.

  19. Investigation of sulfur forms and transformation during the co-combustion of sewage sludge and coal using X-ray photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Li Peisheng; Hu Yi; Yu Wan; Yue Yanan; Xu Qiao; Hu Song; Hu Niansu; Yang Jun

    2009-01-01

    X-ray photoelectron spectroscopy was used to investigate the characteristics and evolution of sulfur (S) in mixtures of bituminous coal and sewage sludge (SS) and their chars during isothermal combustion. Five groups of mixtures with SS content of 0%, 10%, 20%, 30% and 100%, were examined at different burn-off ratios (β) of 0, 30%, 50%, 70% and 100%. The S in the coal mainly exist as the forms of mercaptan (S1), sulfide (S2), thiophene (S3), sulfoxide (S4), sulfone (S5) and sulfate (S6). During the coal combustion process, the content of S1 and S2 decreased, while that of S3 and S5 increased in the early stage and decreased in the late stage. The S4 content increased throughout the entire process of combustion. Small amount of S6 was detected, showing a fluctuated pattern. The trend of S1, S2, S5 and S6 in SS was alike with that in coal, whereas S4 decreased at the end of combustion. The changing process of S3 in SS was opposite to that of coal, while the composition of S in the mixtures resulted from the mixing of coal and SS. The transformation of each functional group during co-combustion were correlated with their transformation characteristics during the mono-combustion of coal and SS, and no obvious interaction was observed, which demonstrated that the coal-origin and SS-origin sulfur in mixtures kept their own characteristics in the combustion. SS may accumulate on the solid surface as α increase, resulting its significant influence on the evolution of each form of S. When α was low, most of the S-contained functional groups presented the characteristics of coal. The percentage of coal-origin functional groups declined as α increased. The transforming trends of most functional groups were similar with that of SS when α reached 30%.

  20. Electrical and mechanical properties of molecularly functionalized mesoporous silica thin films

    Science.gov (United States)

    Singh, Amit Pratap

    fracture energy. X-ray photoelectron spectroscopy (XPS) of fracture surfaces reveal that for both cases, fracture occurs inside the MPS films, but closer to the Cu overlayer. These measurements, along with nanoindentation, thin film stress and Fourier transform infrared (FTIR) spectroscopy measurements further reveal that silylation modifies the mechanical properties of the MPS films. Analysis of fracture surface chemistry using variable take-off angle X-ray photoelectron spectroscopy (ARXPS) and depth profiling shows that the fracture pathway is governed by the depth of metal penetration into the MPS layer during vapor-deposition. Similar changes in mechanical properties were observed in MPS films functionalized with cyanide- (CTS-MPS) and mercaptan-terminated (MPTS-MPS) organosilanes. Thermal stability of CTS-MPS and MPTS-MPS was studied by annealing the films at temperatures up to 500°C in vacuum, nitrogen and air. XPS and Auger electron spectroscopy analyses indicate that the molecules are attached to the external surfaces of the films as well as the pores inside the films. The cyanide-functionalized MPS films are stable up to 500°C in vacuum, N2 and air ambient. In contrast, mercaptan-functionalized MPS films are stable only up to 400°C in vacuum due to the higher reactivity of mercaptan with oxygen. Another key finding of this thesis is that the pore structure in MPS films is a crucial factor that governs their electrical and mechanical properties. MPS films with ordered pores oriented parallel to the substrate (2D-hexagonal) exhibit more than a 4-fold enhancement in Cu-induced dielectric breakdown time in comparison to pores organized in a cubic fashion (3D-cubic). Additionally, upon silylation there is more than 50% decrease in elastic modulus of 2-D hexagonal MPS films in comparison to 20% in 3D-cubic MPS films. Four-point bend measurements on Si(100)/epoxy/Ti/Cu/MPS/Si(001) stacks show that MPS films with 2D-hexagonal MPS films exhibit a lower fracture

  1. Fabrication, characterization, and applications of nanometer-scale features within organomercaptan self- assembled monolayers

    Science.gov (United States)

    Schoer, Jonathan Kevin

    1997-10-01

    Nanometer-scale features in organomercaptan self- assembled monolayers (SAMs) on Au(111) substrates were prepared by three methods: electrochemical enhancement of adventitious defects, electrochemical enhancement of template-molecule-induced pores, and scanning tunneling microscopy (STM)-induced patterning. The resulting features were characterized by electrochemistry, scanning electron microscopy (STM), and electrochemical STM (ECSTM). Finally, we applied STM-induced patterning methods to lithographic fabrication of features with critical dimensions resists and barrier layers to electron and mass transfer. Further, the nanometer-scale features act as nanometer- size electrodes. Measurements of the physical dimensions of nanometer- scale features by STM can be combined with microelectrode theory to calculate a value for the limiting current. Comparison of this value with that obtained directly from conventional electrochemistry provides qualitative agreement. From in-depth studies of the mechanistic aspects of STM- induced patterning of organomercaptan SAMs we determined that this process is controlled by a complex combination of parameters defined by both the instrument and the chemical and physical properties of materials in the vicinity of the tip. In particular, the patterning is dependent on the magnitude and polarity of the gap bias, the Coulomb dose, and the composition of the gap. From this information we propose a detailed multi-step model for STM-induced removal of n-alkanethiol SAMs from Au surfaces. The model is partially based on our observation that high tip bias ([>]~[+]2.30 V) results in removal of SAMs by Faradaic electrochemical processes in which the n-octadecyl mercaptan monolayer is: (1) disrupted by the tip, (2) electrochemically desorbed, and (3) removed by the scanning action of the tip. Further, we determined that at biases above a second threshold (~[+]4.0 V) the patterning becomes irreproducible because the patterning mechanism changes to

  2. Identificação e quantificação de voláteis de café através de cromatografia gasosa de alta resolução / espectrometria de massas empregando um amostrador automático de "headspace" Identification and quantification of coffee volatile components through high resolution gas chromatoghaph/mass spectrometer using a headspace automatic sampler

    Directory of Open Access Journals (Sweden)

    Leonardo César AMSTALDEN

    2001-01-01

    Full Text Available Usando um amostrador automático, os "headspaces" de três marcas comerciais de café torrado e moído foram analisados qualitativa e quantitativamente quanto a composição dos voláteis responsáveis pelo aroma através da técnica de cromatografia gasosa/espectrometria de massas. Uma vez que a metodologia não envolveu isolamento ou concentração dos aromas, suas proporções naturais foram mantidas, além de simplificar o preparo das amostras. O emprego do amostrador automático permitiu também boa resolução dos picos cromatográficos sem o emprego de criogenia, contribuindo para redução no tempo de análise. Noventa e um componentes puderam ser identificados, sendo que alguns compostos conhecidos como presentes em café como o dimetilsulfeto, metional e furfuril mercaptana não foram detectados. Os voláteis presentes em maior concentração puderam ser quantificados com o auxílio de dois padrões internos. A técnica se provou viável, tanto para caracterização como para quantificação de voláteis de café.Employing an automatic headspace sampler, the headspaces of three commercial brands of ground roasted coffee were qualitatively and quantitatively analyzed by gas chromatography / mass spectrometry. Since the methodology did not involve aroma isolation or concentration, their natural proportions were maintained, providing a more accurate composition of the flavors, and simplifying sample preparation. The automatic sampler allowed good resolution of the chromatographic peaks without cryofocusing the samples at the head of the column during injection, reducing analysis time. Ninety one compounds were identified and some known coffee volatiles, such as dimethyl sulphide, methional and furfuryl mercaptan were not detected. The more concentrated volatiles could be identified using two internal standards. The technique proved viable, for both characterization and for quantification of coffee volatiles.

  3. Volatile compounds of Domiati cheese made from buffaloe's milk with different fat content.

    Directory of Open Access Journals (Sweden)

    El-Mageed, Magda A. Abd

    1997-12-01

    Full Text Available Buffaloe's milk was manufactured to Domiati cheese with different fat content in the cheese milk (1%, 3.5% and 7%. Results obtained during the ripening period revealed that the low fat cheese (Karish is not able to long period storage, while half cream cheese had a good quality and flavour along the ripening period. The full cream cheese did not exceed the first month of ripening, then it deteriorated. The main components found were acrolein (propenal, heptanal, acetone, butan-2 one, ethanol, butan-2 ol, 2-methylpropan- 1-ol, 3-methyl butan-1-ol, ethyl propionate, propyl propionate, pentane and octane. Methyl mercaptan, methyl thiopropionate, and dimethyl trisulfide together with propyl butyrate, were existed in the samples which are characterized as bad cheese samples. Most of the previous compounds were developed after 1 month of ripening period.

    La leche de búfalo fue procesada para obtener queso Domiati con diferente contenido graso en la cuajada (1%, 3.5% y 7%. Los resultados obtenidos durante el período de maduración revelaron que el queso con bajo contenido en grasa (Karish no permite un largo período de almacenamiento, mientras que el queso con un contenido medio en grasa tuvo una buena calidad y flavor durante el período de maduración. El queso con alto contenido graso no duró más que el primer mes de maduración, deteriorándose posteriormente. Los principales componentes encontrados fueron acroleína (propenal, heptanal, acetona, butan-2-ona, etanol, butan-2-ol, 2- metil-propan-1-ol, 3 metil butan-1-ol, propionato de etilo, propionate de propilo, pentano y octano. Metil mercaptol, tiopropionato de metilo y trisulfuro de dimetilo Junto con butirato de propilo se encontraron en muestras que fueron caracterizadas como muestras de quesos malos. La mayoría de los compuestos anteriores se produjeron después de un mes de período de maduración.

  4. Determination of hydrogen sulfide and volatile thiols in air samples by mercury probe derivatization coupled with liquid chromatography-atomic fluorescence spectrometry.

    Science.gov (United States)

    Bramanti, Emilia; D'Ulivo, Lucia; Lomonte, Cristina; Onor, Massimo; Zamboni, Roberto; Raspi, Giorgio; D'Ulivo, Alessandro

    2006-10-02

    A new procedure is proposed for the sampling and storage of hydrogen sulphide (H2S) and volatile thiols (methanethiol or methyl mercaptan, ethanethiol and propanethiol) for their determination by liquid chromatography. The sampling procedure is based on the trapping/pre-concentration of the analytes in alkaline aqueous solution containing an organic mercurial probe p-hydroxymercurybenzoate, HO-Hg-C6H4-COO- (PHMB), where they are derivatized to stable PHMB complexes based on mercury-sulfur covalent bonds. PHMB complexes are separated on a C18 reverse phase column, allowing their determination by liquid chromatography coupled with sequential non-selective UV-vis (DAD) and mercury specific (chemical vapor generation atomic fluorescence spectrometry, CVGAFS) on-line detectors. PHMB complexes, S(PHMB)2CH3S-PHMB, C2H5S-PHMB and C3H7S-PHMB, are stable alt least for 12 h at room temperature and for 3 months if stored frozen (-20 degrees C). The best analytical figures of merits in the optimized conditions were obtained by CVGAFS detection, with detection limits (LODc) of 9.7 microg L(-1) for H2S, 13.7 microg L(-1) for CH(3)SH, 17.7 microg L(-1) for C2H5SH and 21.7 microg L(-1) for C3H7SH in the trapping solution in form of RS-PHMB complexes, the relative standard deviation (R.S.D.) ranging between 1.0 and 1.5%, and a linear dynamic range (LDR) between 10 and 9700 microg L(-1). Conventional UV absorbance detectors tuned at 254 nm can be employed as well with comparable R.S.D. and LDR, but with LODc one order of magnitude higher than AFS detector and lower specificity. The sampling procedure followed by LC-DAD-CVGAFS analysis has been validated, as example, for H2S determination by a certified gas permeation tube as a source of 3.071+/-0.154 microg min(-1) of H2S, giving a recovery of 99.8+/-7% and it has been applied to the determination of sulfur compounds in real gas samples (biogas and the air of a plant for fractional distillation of crude oil).

  5. Avaliação da incorporação de resíduo de poli(etileno-co-acetato de vinila em borracha nitrílica Evaluation of waste poly(ethylene-co-vinyl incorporation in nitrile rubber

    Directory of Open Access Journals (Sweden)

    Viviane X. Moreira

    2003-01-01

    Full Text Available A influência do resíduo de poli(etileno-co-acetato de vinila (EVAR no desempenho mecânico de composições vulcanizadas de NBR foi estudada. A concentração ótima de EVAR, a qual apresentou maior valor de tensão na ruptura, foi de 50 phr. Além disso, a influência do EVA e do EVAR funcionalizado com grupos tióis (EVALSH e do EVAR modificado com anidrido maleico (EVARCO como agentes compatibilizantes foi estudada. O copolímero EVALSH atuou como acelerador no processo de vulcanização, sendo observado um decréscimo do tempo de vulcanização. Uma melhora na resistência ao envelhecimento também foi observada. A adição de 10 phr de EVARCO resultou na redução do tempo de vulcanização e em uma melhora na maior parte das propriedades avaliadas. As propriedades termodinâmico-mecânicas foram avaliadas por análises de DMTA. Os estudos da interação entre a fase dispersa e a fase matriz foram realizados utilizando-se microscopia eletrônica de varredura (MEV.The influence of poly(ethylene-co-vinyl acetate (EVA waste (EVAR on the mechanical performance of NBR vulcanisates compounds was studied. The optimum concentration of EVAR, which has presented higher ultimate tensile stress, was found at 50 phr. In addition, the influence of EVA and EVAR functionalized with mercaptan groups (EVALSH and EVAR functionalized with maleic anidride (EVARCO as compatibilizing agents was studied. The copolymer EVALSH acted as accelerator for the curing system, since a decreasing of the curing time was observed. An improvement of ageing resistance was also observed. The addition of EVARCO resulted in a reduction of the curing time and an improvement of most of evaluated properties. The thermodynamic-mechanic properties were investigated by DMTA analysis. The studies on the interaction between dispersed phase and matrix were performed by scanning electron microscopy (SEM.

  6. A randomized double blind crossover placebo-controlled clinical trial to assess the effects of a mouthwash containing chlorine dioxide on oral malodor

    Directory of Open Access Journals (Sweden)

    Yokoyama Sayaka

    2008-12-01

    Full Text Available Abstract Background Previous research has shown the oxidizing properties and microbiological efficacies of chlorine dioxide (ClO2, however, its clinical efficacies on oral malodor have been evaluated only with organoleptic measurements (OM or sulphide monitors. No clinical studies have investigated the inhibitory effects of ClO2 on volatile sulfur compounds (VSCs using gas chromatography (GC. The aim of this study was to assess the inhibitory effects of a mouthwash containing ClO2 on morning oral malodor using OM and GC. Methods A randomized, double blind, crossover, placebo-controlled clinical trial was conducted among 15 healthy male volunteers, who were divided into 2 groups. In the first test phase, the group 1 subjects (N = 8 were instructed to rinse with the experimental mouthwash containing ClO2, and those in group 2 (N = 7 to rinse with the placebo mouthwash without ClO2. In the second test, phase after a one week washout period, each group used the opposite mouthwash. Oral malodor was evaluated before rinsing, right after rinsing and every 30 minutes up to 4 hours with OM, and concentrations of hydrogen sulfide (H2S, methyl mercaptan (CH3SH and dimethyl sulfide ((CH32S, the main VSCs of human oral malodor, were evaluated with GC. Results The baseline oral condition in the subjects in the 2 groups did not differ significantly. The mouthwash containing ClO2 improved morning bad breath according to OM and reduced concentrations of H2S, CH3SH and (CH32S according to GC up to 4 hours after rinsing. OM scores with ClO2 were significantly lower than those without ClO2 at all examination times. Significant reductions in the concentrations of the three kinds of VSCs measured by GC were also evident at all examination times. The concentrations of the three gases with ClO2 were significantly lower than those without ClO2 at most examination times. Conclusion In this explorative study, ClO2 mouthwash was effective at reducing morning malodor for 4

  7. Kashagan oil field development. Kazakhstan

    International Nuclear Information System (INIS)

    Urbaniak, D.; Gerebizza, E.; Wasse, G.; Kochladze, M.

    2007-12-01

    Based on our research and field investigations of the Kashagan oil field development and relevant infrastructure in the Atyrau and Mangistau regions of Kazakhstan (cities and vicinities of Aktau, Atash, Atyrau, Bautino, Bolashak, Karabatan and Koshanai) evidence has been collected that raises serious concerns about environmental, social and health effects of this oil field development - such as sulphur emissions and storage which may pose serious threats for the communities close to the Kashagan oil facilities and for the Caspian Sea environment. Furthermore, since becoming the single Operator of the North Caspian Sea Production Sharing Agreement (PSA), the Agip Kazakhstan North Caspian Operating Company N.V. (Agip KCO) has failed to release all information available on the environmental, health and social impacts of its operations in the Kashagan oil field. As requested by the local communities and required by Constitution of Kazakhstan Republic and Aarhus Convention on Access to Information, Public Participation in Decision-Making and Access to Justice in Environmental Matters ratified by Kazakhstan in 2001, such information must be made available. There is also a growing concern among the civil society that the European Commission through its officials is publicly expressing support to European oil companies' members of the Agip KCO despite their failure to fulfil basic environmental regulations. This continued support contradicts the European Union's fundamental values and frequent statements related to Human Rights and Sustainable Development. Thousands of people have already been relocated in the region because of sulphur emissions and other highly poisonous chemicals such as mercaptans, which are present at very high levels in Northern Caspian oil. Unprotected storage of large quantities of sulphur is also recognised as a major cause of acid rain on a global level. This Report implores Agip KCO to release all available and required information on the

  8. Cancer chemoprevention and nutriepigenetics: state of the art and future challenges.

    Science.gov (United States)

    Gerhauser, Clarissa

    2013-01-01

    (I3C), diindolylmethane (DIM), sulforaphane, phenylethyl isothiocyanate (PEITC), phenylhexyl isothiocyanate (PHI), diallyldisulfide (DADS) and its metabolite allyl mercaptan (AM), cambinol, and relatively unexplored modulators of histone lysine methylation (chaetocin, polyamine analogs). So far, data are still mainly derived from in vitro investigations, and results of animal models or human intervention studies are limited that demonstrate the functional relevance of epigenetic mechanisms for health promoting or cancer preventive efficacy of natural products. Also, most studies have focused on single candidate genes or mechanisms. With the emergence of novel technologies such as next-generation sequencing, future research has the potential to explore nutriepigenomics at a genome-wide level to understand better the importance of epigenetic mechanisms for gene regulation in cancer chemoprevention.

  9. Startup and long-term performance of biotrickling filters packed with polyurethane foam and poplar wood chips treating a mixture of ethylmercaptan, H2S, and NH3.

    Science.gov (United States)

    Hernández, J; Lafuente, J; Prado, O J; Gabriel, D

    2013-04-01

    Treatment of a mixture of NH3, H2S, and ethylmercaptan (EM) was investigated for more than 15 months in two biotrickling filters packed with poplar wood chips and polyurethane foam. Inlet loads ranging from 5 to 10 g N-NH3 m-3 hr-1, from 5 to 16 g S-H2S m-3 hr-1, and from 0 to 5 g EM m-3 hr-1 were applied. During startup, the biotrickling filter packed with polyurethane foam was re-inoculated due to reduced biomass retention as well as a stronger effect of nitrogen compounds inhibition compared with the biotrickling filter packed with poplar wood. Accurate pH control between 7 and 7.5 favored pollutants abatement. In the long run, complete NH3 removal in the gas phase was achieved in both reactors, while H2S removal efficiencies exceeded 90%. EM abatement was significantly different in both reactors. A systematically lower elimination capacity was found in the polyurethane foam bioreactor. N fractions in the liquid phase proved that high nitrification rates were reached throughout steady-state operation in both bioreactors. CO2 production showed the extent of the organic packing material degradation, which allowed estimating its service lifetime in around 2 years. In the long run, the bioreactor packed with the organic packing material had a lower stability. However, an economic analysis indicated that poplar wood chips are a competitive alternative to inorganic packing materials in biotrickling filters. We provide new insights in the use of organic packing materials in biotrickling filters for the treatment of H2S, NH3, and mercaptans and compare them with polyurethane foam, a packing commonly used in biotrickling filters. We found interesting features related with the startup of the reactors and parameterized both the performance under steady-state conditions and the influence of the gas contact time. We provide relevant conclusions in the profitability of organic packing materials under a biotrickling filter configuration, which is infrequent but proven reliable

  10. Use of Multi-Objective Air Pollution Monitoring Sites and Online Air Pollution Monitoring System for Total Health Risk Assessment in Hyderabad, India

    Directory of Open Access Journals (Sweden)

    K. V. Ramani

    2005-08-01

    -time monitoring system was designed using advanced electrochemical sensor systems (sulphur dioxide, oxides of nitrogen, carbon monoxide, hydrocarbons, ozone, mercaptans and hydrogen sulphide and a particulate matter analyzer (total suspended particulate matter TSPM, PM2.5 and PM10. The sensor and data acquisition systems are programmed to monitor pollution levels at ½ hour durations during peak hours and at 1-hour intervals at other times. Presently, extensive statistical and numerical simulations are being carried out at our center to correlate the individuals living in the monitored areas with respiratory infections with air pollution.

  11. Calibration transfer between electronic nose systems for rapid In situ measurement of pulp and paper industry emissions

    Energy Technology Data Exchange (ETDEWEB)

    Deshmukh, Sharvari [CSIR-National Environmental Engineering and Research Institute, Nagpur (India); Department of Instrumentation and Electronics Engineering, Jadavpur University, Kolkata (India); Kamde, Kalyani [CSIR-National Environmental Engineering and Research Institute, Nagpur (India); Jana, Arun [Center for Development of Advance Computing, Kolkata (India); Korde, Sanjivani [CSIR-National Environmental Engineering and Research Institute, Nagpur (India); Bandyopadhyay, Rajib [Department of Instrumentation and Electronics Engineering, Jadavpur University, Kolkata (India); Sankar, Ravi [Center for Development of Advance Computing, Kolkata (India); Bhattacharyya, Nabarun, E-mail: nabarun.bhattacharya@cdac.in [Center for Development of Advance Computing, Kolkata (India); Pandey, R.A., E-mail: ra_pandey@neeri.res.in [CSIR-National Environmental Engineering and Research Institute, Nagpur (India)

    2014-09-02

    Highlights: • E-nose developed for obnoxious emissions measurement at pulp and paper industrial site. • ANN model developed for prediction of (CH{sub 3}){sub 2}S, (CH{sub 3}){sub 2}S{sub 2}, CH{sub 3}SH and H{sub 2}S concentration. • Calibration transfer methodology developed for transfer between two e-nose instruments. • Box–Behnken design and robust regression used for calibration transfer. • Results show effective transfer of training model from one e-nose system to other. - Abstract: Electronic nose systems when deployed in network mesh can effectively provide a low budget and onsite solution for the industrial obnoxious gaseous measurement. For accurate and identical prediction capability by all the electronic nose systems, a reliable calibration transfer model needs to be implemented in order to overcome the inherent sensor array variability. In this work, robust regression (RR) is used for calibration transfer between two electronic nose systems using a Box–Behnken (BB) design. Out of the two electronic nose systems, one was trained using industrial gas samples by four artificial neural network models, for the measurement of obnoxious odours emitted from pulp and paper industries. The emissions constitute mainly of hydrogen sulphide (H{sub 2}S), methyl mercaptan (MM), dimethyl sulphide (DMS) and dimethyl disulphide (DMDS) in different proportions. A Box–Behnken design consisting of 27 experiment sets based on synthetic gas combinations of H{sub 2}S, MM, DMS and DMDS, were conducted for calibration transfer between two identical electronic nose systems. Identical sensors on both the systems were mapped and the prediction models developed using ANN were then transferred to the second system using BB–RR methodology. The results showed successful transmission of prediction models developed for one system to other system, with the mean absolute error between the actual and predicted concentration of analytes in mg L{sup −1} after calibration

  12. Transition-metal-catalyzed enantioselective heteroatom-hydrogen bond insertion reactions.

    Science.gov (United States)

    Zhu, Shou-Fei; Zhou, Qi-Lin

    2012-08-21

    Carbon-heteroatom bonds (C-X) are ubiquitous and are among the most reactive components of organic compounds. Therefore investigations of the construction of C-X bonds are fundamental and vibrant fields in organic chemistry. Transition-metal-catalyzed heteroatom-hydrogen bond (X-H) insertions via a metal carbene or carbenoid intermediate represent one of the most efficient approaches to form C-X bonds. Because of the availability of substrates, neutral and mild reaction conditions, and high reactivity of these transformations, researchers have widely applied transition-metal-catalyzed X-H insertions in organic synthesis. Researchers have developed a variety of rhodium-catalyzed asymmetric C-H insertion reactions with high to excellent enantioselectivities for a wide range of substrates. However, at the time that we launched our research, very few highly enantioselective X-H insertions had been documented primarily because of a lack of efficient chiral catalysts and indistinct insertion mechanisms. In this Account, we describe our recent studies of copper- and iron-catalyzed asymmetric X-H insertion reactions by using chiral spiro-bisoxazoline and diimine ligands. The copper complexes of chiral spiro-bisoxazoline ligands proved to be highly enantioselective catalysts for N-H insertions of α-diazoesters into anilines, O-H insertions of α-diazoesters into phenols and water, O-H insertions of α-diazophosphonates into alcohols, and S-H insertions of α-diazoesters into mercaptans. The iron complexes of chiral spiro-bisoxazoline ligands afforded the O-H insertion of α-diazoesters into alcohols and water with unprecedented enantioselectivities. The copper complexes of chiral spiro-diimine ligands exhibited excellent reactivity and enantioselectivity in the Si-H insertion of α-diazoacetates into a wide range of silanes. These transition-metal-catalyzed X-H insertions have many potential applications in organic synthesis because the insertion products, including chiral

  13. Methane-free biogas for direct feeding of solid oxide fuel cells

    Science.gov (United States)

    Leone, P.; Lanzini, A.; Santarelli, M.; Calì, M.; Sagnelli, F.; Boulanger, A.; Scaletta, A.; Zitella, P.

    This paper deals with the experimental analysis of the performance and degradation issues of a Ni-based anode-supported solid oxide fuel cell fed by a methane-free biogas from dark-anaerobic digestion of wastes by pastry and fruit shops. The biogas is produced by means of an innovative process where the biomass is fermented with a pre-treated bacteria inoculum (Clostridia) able to completely inhibit the methanization step during the fermentation process and to produce a H 2/CO 2 mixture instead of conventional CH 4/CO 2 anaerobic digested gas (bio-methane). The proposed biogas production route leads to a biogas composition which avoids the need of introducing a reformer agent into or before the SOFC anode in order to reformate it. In order to analyse the complete behaviour of a SOFC with the bio-hydrogen fuel, an experimental session with several H 2/CO 2 synthetic mixtures was performed on an anode-supported solid oxide fuel cell with a Ni-based anode. It was found that side reactions occur with such mixtures in the typical thermodynamic conditions of SOFCs (650-800 °C), which have an effect especially at high currents, due to the shift to a mixture consisting of hydrogen, carbon monoxide, carbon dioxide and water. However, cells operated with acceptable performance and carbon deposits (typical of a traditional hydrocarbon-containing biogas) were avoided after 50 h of cell operation even at 650 °C. Experiments were also performed with traditional bio-methane from anaerobic digestion with 60/40 vol% of composition. It was found that the cell performance dropped after few hours of operation due to the formation of carbon deposits. A short-term test with the real as-produced biogas was also successfully performed. The cell showed an acceptable power output (at 800 °C, 0.35 W cm -2 with biogas, versus 0.55 W cm -2 with H 2) although a huge quantity of sulphur was present in the feeding fuel (hydrogen sulphide at 103 ppm and mercaptans up to 10 ppm). Therefore, it

  14. Effects of a mouthwash with chlorine dioxide on oral malodor and salivary bacteria: a randomized placebo-controlled 7-day trial

    Directory of Open Access Journals (Sweden)

    Ohnuki Mari

    2010-02-01

    Full Text Available Abstract Background Previous research has shown the oxidizing properties and microbiological efficacies of chlorine dioxide (ClO2. Its clinical efficacies on oral malodor have been evaluated and reported only in short duration trials, moreover, no clinical studies have investigated its microbiological efficacies on periodontal and malodorous bacteria. Thus, the aim of this study was to assess the inhibitory effects of a mouthwash containing ClO2 used for 7 days on morning oral malodor and on salivary periodontal and malodorous bacteria. Methods/Design A randomized, double blind, crossover, placebo-controlled trial was conducted among 15 healthy male volunteers, who were divided into 2 groups. Subjects were instructed to rinse with the experimental mouthwash containing ClO2 or the placebo mouthwash, without ClO2, twice per day for 7 days. After a one week washout period, each group then used the opposite mouthwash for 7 days. At baseline and after 7 days, oral malodor was evaluated with Organoleptic measurement (OM, and analyzed the concentrations of hydrogen sulfide (H2S, methyl mercaptan (CH3SH and dimethyl sulfide ((CH32S, the main VSCs of human oral malodor, were assessed by gas chromatography (GC. Clinical outcome variables included plaque and gingival indices, and tongue coating index. The samples of saliva were microbiologically investigated. Quantitative and qualitative analyses were performed using the polymerase chain reaction-Invader method. Results and Discussion The baseline oral condition in healthy subjects in the 2 groups did not differ significantly. After rinsing with the mouthwash containing ClO2 for 7 days, morning bad breath decreased as measured by the OM and reduced the concentrations of H2S, CH3SH and (CH32S measured by GC, were found. Moreover ClO2 mouthwash used over a 7-day period appeared effective in reducing plaque, tongue coating accumulation and the counts of Fusobacterium nucleatum in saliva. Future research is

  15. Etude du mécanisme d'action du dialkyldithiophosphate de zinc en régime de lubrification limite Mechanism of Boundary Lubrication with Zinc Dialkyldithiophosphates

    Directory of Open Access Journals (Sweden)

    Morizur-Jersale M. F.

    2006-11-01

    Full Text Available Le mécanisme d'action de l'isobutyl-isopentyl dithiophosphate de zinc en régime de lubrification limite a été étudié grâce à la comparaison des films superficiels apparaissant par simple immersion et au cours du frottement, en présence de cet additif. Deux étapes de ce mécanisme ont ainsi pu être mises en évidence : 1 Avant sa décomposition dans l'huile, le DTPZn réagit avec la surface pour former un film de sulfure et d'oxyde métallique dont l'épaisseur ne peut atteindre généralement que quelques 1/1000 de micromètre Cette réaction se traduit, au niveau de la molécule, par la rupture d'une partie des liaisons thiophosphorées et par un échange ionique entre le métal support et Zn2+. 2 Après la dégradation, dans l'huile, des liaisons P-O-C de la molécule de DTPZn, les produits phosphorés de cette décomposition s'adsorbent ou réagissent en surface pour constituer un film de phosphates de quelques 1/10 de micromètre. Parallèlement les produits soufrés (mercaptans, disulfures, issus de la décomposition du DTPZn dans l'huile ou en surface, réagissent indépendamment avec le métal. L'activité extrême-pression de l'additif qui provient de la formation de sulfure métallique en surface est donc fonction de l'affinité du métal support vis-à-vis du soufre. Bien que l'effet de la température ne suffise pas à expliquer la décomposition du DTPZn, au cours du frottement, les intermédiaires réactionnels de la dégradation de l'additif par simple chauffage ou entre les éprouvettes de frottement sont très proches. En effet, la décomposition partielle de l'additif, par chauffage préalable, favorise la formation du film phosphoré sur les surfaces de frottement, ce qui confère au lubrifiant une efficacité plus grande. The action mechanism of isobutyl-isopentyl zinc dithiophosphate in the boundary lubrication regime was analyzed by comparing surface films appearing by simple immersion and during friction, in the

  16. From petal effect to lotus effect: a facile solution immersion process for the fabrication of super-hydrophobic surfaces with controlled adhesion

    Science.gov (United States)

    Cheng, Zhongjun; Du, Ming; Lai, Hua; Zhang, Naiqing; Sun, Kening

    2013-03-01

    adhesion is ascribed to the different wetting states for the droplet on the surface that results from the change of the morphology and microstructure scale after the thiolate reaction. Noticeably, the as-prepared surfaces are acid/alkali-resisting; the acidic and basic water droplets have similar contact angles and adhesive forces to that of the neutral water droplet. Moreover, we demonstrate a proof of water droplet transportation for application in droplet-based microreactors via our surfaces. We believe that the results reported here would be helpful for the further understanding of the effect of wetting states on the surface adhesion and the fabrication principle for a super-hydrophobic surface with controlled adhesion. Electronic supplementary information (ESI) available: Experimental details for the fabrication of ball-like structured Cu(OH)2; XRD of Cu(OH)2; SEM images of the surfaces after reaction in an ethanol solution of n-octyl mercaptan with different concentrations; dependence of the contact angles on the chain length of the thiols; contact angle on the flat copper surface and the discussion of the super-hydrophobicity of the as-prepared surfaces; SEM images of the surfaces after reaction with different thiols at a constant time. See DOI: 10.1039/c3nr34256e

  17. Modern view on hepatic encephalopathy: basic terms and concepts of pathogenesis

    Directory of Open Access Journals (Sweden)

    T. V. Shulyatnikova

    2017-12-01

    Full Text Available Background. The problem of acute and chronic forms of hepatic encephalopathy (HE is not clearly identified among modern problems of hepatology and neuroscience in Ukraine. Despite the significant contribution to the development of lethal complications in patients with liver pathology and long history of the study of this issue, there is still no unified opinion on the links of HE pathogenesis. The aim of this review is to conduct a comprehensive analysis of current data on the spreading and mechanisms of development of HE. HE is a complex of potentially reversible neurocognitive disorders in patients with chronic or acute hepatic failure (ALF. HE is more often a complication of liver cirrhosis and is the second most frequent cause of hospitalization of such patients after ascites. When decompensating liver failure in acute or chronic hepatic pathology in patients severe forms of HE develop, accompanied by a progressive increase in intracranial pressure and the development of coma, which often ends lethal due to poor corrigibility of intracranial hypertension while maintaining hepatogenic neurointoxication. HE is considered as the end result of the accumulation of a number of neurotoxic substances in the brain, among which are ammonia, mercaptans, short chain fatty acids, false neurotransmitters, gamma-aminobutyric acid, manganese. The most popular among the reasons for the development of HE is the neurotoxic theory of ammonia. Ammonia is subjected to detoxification in the liver, turning into urea, a smaller fraction with the participation of glutamine synthetase is used in the synthesis of glutamine in muscles, liver and astrocytes of brain. In case of hepatic dysfunction and/or portosystemic shunting, the concentration of ammonia in blood increases up to 10 times and the main load for its detoxification is shifted to myocytes and astroglia. In ALF glutamine overload of astrocytes occurs with a change in intracellular osmolarity and subsequent

  18. Nuisance Odors: Is there a Concern - 12340

    Energy Technology Data Exchange (ETDEWEB)

    Brounstein, Robert A. [TerranearPMC, Los Alamos New Mexico 87544 (United States)

    2012-07-01

    Nuisance odors are generally thought of as just being annoying or unpleasant and not causing any physiological harm to our internal organs or other biologic systems. Yet during an excavation of buried animal remains, field workers experienced a multitude of symptoms that are associated with exposures to toxic materials. An examination of the decomposition process revealed that there is a potential off-gassing of a number of common, yet harmful chemicals including ammonia, mercaptans, hydrogen sulfide, butyric acid and phenol. In addition, other compounds, that have limited information such as established health data and occupational exposure limits, were also potential contaminants-of-concern. While a variety of monitoring and sampling techniques were used to assess worker exposures, all results indicated non-detectable airborne concentrations. Nevertheless, workers were experiencing such symptoms as nausea and headaches. As such, protective measures were necessary for field personnel to continue work while having confidence that the project was instituting sincere steps to ensure their health and safety. Researching the possible reasons for the causes of workers exhibiting adverse health effects from nuisance odors revealed that such exposures initiate electrochemical pathways, starting from the olfactory bulb to the brain, followed by a transfer of information to such biologic systems as the hypothalamus and pituitary gland. These systems, in turn, secrete hormones that cause a number of involuntary reactions; many of which are observed as typical adverse health effects, when in fact, they are merely reactions caused by the brain's memory; most likely created from previous experiences to unpleasant odors. The concern then focuses of how the Occupational Safety and Health community shall respond to such workplace exposures. Future work in this area may need to focus on the viability of current occupational exposure limits and the possibility of revising these