Дисертації з теми "Radical hydroxyl"
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Smith, Mathew D. "Reaction of hydroxyl radical with aromatic systems." Virtual Press, 2008. http://liblink.bsu.edu/uhtbin/catkey/1399191.
Повний текст джерелаDepartment of Chemistry
Mitroka, Susan M. "Modulation of Hydroxyl Radical Reactivity and Radical Degradation of High Density Polyethylene." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/77137.
Повний текст джерелаPh. D.
Lenton, K. J. "Hydroxyl radical scavengers and antioxidants in radiation protection." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ32339.pdf.
Повний текст джерелаMcKay, Garrett J. "Reactivity of the hydroxyl radical with organic matter." Thesis, California State University, Long Beach, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1527332.
Повний текст джерелаThe goal of this study was to investigate some of the fundamental chemistry of the reactions between the hydroxyl radical and apply this knowledge to the treatment of chemical contaminants in real world waters. To accomplish this goal, the techniques of electron pulse radiolysis were used to quantify second-order rate constants for the reaction between the HO· radical and well characterized OM samples. Studies of HO· radical reactivity with model polyethylene glycol polymers were performed to help understand OM-HO· reactivity. Experiments using steady state radiolysis were performed in order to assess the effect of long-term, seasonal variability in OM composition on the degradation of probe compounds used as model chemical contaminants. In addition, the photochemical production of HO· from OM sensitization was also investigated.
Black, Helen Dinah. "Kinetics of hydroxyl radical reactions with heterocyclic compounds." Thesis, University of Leeds, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305373.
Повний текст джерелаAsuru, Awuri P. "Applications of X-ray Hydroxyl Radical Protein Footprinting." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1575877091577049.
Повний текст джерелаDahlstrom, Stephen W. "Hydroxyl radical activity in bleached root-filled teeth /." Title page, contents and summary only, 1992. http://web4.library.adelaide.edu.au/theses/09DM/09dmd131.pdf.
Повний текст джерелаAkin, Myles. "Site specific thermodynamic study of OH radical addition to DNA bases." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33919.
Повний текст джерелаBarreto, Joao Pedro Cabaco Moniz. "Dioxygen free radical reactions." Thesis, Oxford Brookes University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389105.
Повний текст джерелаHoutz, Erika. "Hydroxyl radical production in Old Woman Creek National Estuarine Reserve." Connect to resource, 2007. http://hdl.handle.net/1811/28931.
Повний текст джерелаTitle from first page of PDF file. Document formatted into pages: contains iii, 24 p.; also includes graphics. Includes bibliographical references (p. 32-24). Available online via Ohio State University's Knowledge Bank.
Cullen, Thomas Donovan. "Hydroxyl radical reaction and lanthanide ion complexation kinetics of DTPA." Thesis, California State University, Long Beach, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1524188.
Повний текст джерелаLouie, Peter Kwok Keung. "Kinetics of some gas phase reactions of the hydroxyl radical." Thesis, University of Leeds, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.236874.
Повний текст джерелаCryer, Danny Russell. "Measurements of hydroxyl radical reactivity and formaldehyde in the atmosphere." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/16834/.
Повний текст джерелаAltizer, Chase Duncan. "Hydroxyl Radical Production via Acoustic Cavitation in Ultrasonic Humidifier Systems." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/95935.
Повний текст джерелаMS
Silvester, Stephen. "The copper-catalyzed oxidation of biologically relevant thiols." Thesis, University of York, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265370.
Повний текст джерелаPark, Ji Ho. "Experimantal and theoretical studies of isoprene oxidation initiated by hydroxyl radical." Texas A&M University, 2004. http://hdl.handle.net/1969.1/1343.
Повний текст джерелаSouthworth, Barbara A. (Barbara Anne) 1973. "Hydroxyl radical production via the photo-Fenton reaction in natural waters." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/17548.
Повний текст джерелаIncludes bibliographical references.
This dissertation investigates the importance of photo-Fenton chemistry in natural waters. The Fenton reaction, H202 + Fe(ll) [right arrow] Fe(ll) + OH- + OH', can occur in sunlit waters because both H202 and Fe(ll) are photo-chemically produced. Photo-Fenton chemistry was investigated by irradiating model systems and natural water samples with simulated sunlight and measuring both H202 accumulation and OH' production in the presence and the absence of Fe reactions. Using these data, a model was developed to calculate the potential impact of the photo-Fenton reaction in sunlit natural waters. Throughout this work, a method based on the chemiluminescent reaction of an acridinium ester compound with the conjugate base of H202 was used to analyze H202. This method is sensitive, and has a greater dynamic range, greater selectivity, and fewer sources of interference than more commonly used methods. However, its behavior is not consistent with a simple reaction mechanism. The kinetics of the chemiluminescent reaction were investigated and a mechanism proposed that can explain its behavior, confirming the ability of this method to accurately measure H202, and suggesting ways to avoid potential problems with its application. The photo-Fenton reaction was studied in model systems consisting of a standard humic substance and amorphous iron oxide exposed to simulated sunlight. A probe method was adapted to allow low concentrations of OH' to be measured without otherwise influencing the chemical reactions occurring in experiments. The difference between measured H202 accumulation in the presence and absence of Fe in these systems was interpreted as the photo-loss of H202 by reaction with Fe(ll).
(cont.) Both this photo-loss, as well as measured losses of H202 by reaction with Fe(ll) in the dark, produced the expected quantities of OH'. The photo-loss of H202, as well as the production of OH' due to Fe, were eliminated by the addition of the iron ligand, desferrioxamine mesylate (DFOM). If Fe is also the major sink of H202 in natural waters, sufficient H202 is produced to be an important sink of organic compounds in relatively shallow fresh waters. The amount of H202 that will react to form OH' in natural waters is dependent on the ability of Fe(ll) to outcompete other sinks of H202. Light attenuation and mixing processes will dilute both H202 and Fe(ll) in natural waters, slowing the reaction rate with each other and decreasing the yield of OH' from H202. To investigate these effects, a model was developed using experimental data for the accumulation of H202 in model systems exposed to different intensities of light and rate constants measured in the dark. Assuming that the same processes occur in natural waters, the effects of light attenuation and mixing were calculated as a function of depth and organic matter concentration. Sufficient Fe(ll) will be produced at pH 6 to result in half-lives of organic compounds due to photo-Fenton chemistry on the order of weeks to months at depths less than 10 meters. The methods used to study photo-Fenton chemistry in model systems were applied to two natural water samples from freshwater systems in which photo-Fenton chemistry is likely to occur ...
by Barbara A. Southworth.
Ph.D.
Shannon, Robin Joseph. "Experimental and computational studies of hydroxyl radical kinetics at very low temperatures." Thesis, University of Leeds, 2012. http://etheses.whiterose.ac.uk/3661/.
Повний текст джерелаIngle, Shakti Singh. "RNA structure investigation: a deuterium kinetic isotope effect/hydroxyl radical cleavage experiment." Thesis, Boston University, 2013. https://hdl.handle.net/2144/12787.
Повний текст джерелаThe hydroxyl radical is widely used as a high-resolution footprinting agent for DNA and RNA. The hydroxyl radical abstracts a hydrogen atom from the sugar- phosphate backbone of a nucleic acid molecule, creating a sugar-based radical that eventually results in a strand break. It was shown previously that replacement of deoxyribose hydrogen atoms with deuterium results in a kinetic isotope effect (KIE) on hydroxyl radical cleavage of DNA. The KIE correlates well with the solvent accessible surface area of a deoxyribose hydrogen atom in DNA. We chose the structurally well-defmed sarcin-ricin loop (SRL) RNA molecule as a model system to extend the deuterium KIE/hydroxyl radical cleavage experiment to RNA. We observed a substantial KIE upon deuteration of the 5'-carbon of the ribose. Values ranged from 1.20 to 1.96, and depended on the position of the residue within the SRL. We found a smaller KIE upon 4'-deuteration. Values ranged from 1.05 to 1.23. Values of 5' and 4' KIEs correlate with the extent of cleavage and with the solvent accessible surface areas of ribose hydrogen atoms ofthe SRL. Gel electrophoresis of cleavage products reveals that the strand break is terminated at the 5' end by multiple chemical species. Upon 3'-radiolabeling a specifically 5'-deuterated SRL RNA molecule, we observed a KIE on the production of a cleavage product having a gel mobility different from that of a phosphate-terminated RNA strand. Reduction with sodium borohydride gave rise to an RNA fragment terminated by a 5'-hydroxyl group. These experiments are consistent with 5' hydrogen abstraction by the hydroxyl radical producing a 5'-aldehyde-terminated RNA strand that retains the nucleotide from which the hydrogen atom was abstracted. This is the first report of such a species. This chemistry has important implications for the interpretation of structural analysis experiments on RNA that rely on primer extension to synthesize eDNA copies of hydroxyl radical cleavage products. The different 5'-terminated products resulting from hydroxyl radical cleavage at a given nucleotide would yield cDNAs of two different lengths, thereby distributing the cleavage intensity over two nucleotides instead ofone and lowering the resolution ofthe experiment.
Shi, Xiaofeng. "Time-Resolved Spectroscopic Studies of the Photochemistry of riboflavin, aromatic N-Oxides and the absolute reactivity of hydroxyl radical." The Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=osu1126795561.
Повний текст джерелаGreenbaum, Jason Adam. "Experimental and computational studies of DNA structure using the hydroxyl radical as a chemical probe." Thesis, Boston University, 2006. https://hdl.handle.net/2144/30677.
Повний текст джерелаPLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
We have constructed a database of hydroxyl radical (•OH) cleavage patterns of DNA in order to investigate the relationship between the sequence of a DNA molecule and its three-dimensional structure. The hydroxyl radical cuts DNA at every nucleotide, with the amount of cutting proportional to the solvent accessible surface area (SASA) of the deoxyribose hydrogen atoms. Cleavage fragments are quantified by a fluorescence sequencer, followed by normalization and deposition into the database. Our database currently contains 151 DNA sequences with lengths ranging from 35 to 41 nucleotides. These data have enabled us to develop some general rules regarding the sequence-dependence of DNA structure as well as to predict the cleavage pattern of any given DNA sequence with remarkable precision. Using this prediction algorithm, it is possible to construct structural maps of entire genomes. As there are many examples of DNA binding proteins with highly degenerate binding sites, the use of structural information to locate these sites may be helpful. There also exists other signals, including the signal for nucleosome positioning, which have no apparent consensus, making it likely that the structure of DNA is of critical importance. We have developed algorithms to identify regions of conserved structure using •OH cleavage intensity as a proxy. Within a set of DNase I hypersensitive sites (DHS) obtained from the ENCODE Consortium, we were able to identify a stretch of 12 nucleotides for which the structural conservation is much greater than the sequence conservation. These sites have been dubbed Conserved •OH Radical Cleavage Signatures, or CORCS. Upon further analysis, these CORCS were found to be 17-fold enriched for DHS as compared to shuffled elements. Through the continued analysis of hydroxyl radical cleavage data and development of algorithms to employ the data in biologically meaningful ways, we hope to further our understanding of the relationship between DNA sequence and structure, and how the local structural heterogeneity of genomic DNA contributes to biological function.
2031-01-02
Semadeni, Marco. "Hydroxyl radical reactions with volatile organic compounds under simulated tropospheric conditions : tropospheric lifetimes /." [S.l.] : [s.n.], 1994. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=10809.
Повний текст джерелаJeune, Gareth Huw. "An investigation into hydroxyl radical processes for the destruction of chemical warfare agents." Thesis, University of Reading, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360079.
Повний текст джерелаVimal, Deepali. "Laboratory investigations of the hydroxyl radical-initiated oxidation of atmospheric volatile organic compounds." [Bloomington, Ind.] : Indiana University, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3324041.
Повний текст джерелаTitle from PDF t.p. (viewed on May 13, 2009). Source: Dissertation Abstracts International, Volume: 69-08, Section: B, page: 4637. Adviser: Philip S. Stevens.
Short, Hayden B. "Chemically Accurate Calculations of Rate Constants of Spin Trap-Hydroxyl Radical Addition Reactions." Digital Commons @ East Tennessee State University, 2015. https://dc.etsu.edu/honors/252.
Повний текст джерелаRagnar, Martin. "On the importance of radical formation in ozone bleaching." Doctoral thesis, Stockholm, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3042.
Повний текст джерелаDunford, Rosemary. "The effect of photoexcited ultrafine titanium dioxide on DNA." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389000.
Повний текст джерелаFortier, Chanel. "Preparation, Characterization, And Application of Liposomes in the Study of Lipid Oxidation Targeting Hydroxyl Radicals." ScholarWorks@UNO, 2008. http://scholarworks.uno.edu/td/889.
Повний текст джерелаMinakata, Daisuke. "Development of aqueous phase hydroxyl radical reaction rate constants predictors for advanced oxidation processes." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37127.
Повний текст джерелаNitisha, Hiranandani. "Impact of Reperfusion Injury on Heart." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1239720273.
Повний текст джерелаAlkhuraiji, Turki. "Ionisation par faisceau d'électrons de solutions aqueuses de benzènesulfonate et naphthalènesulfonate et sous-produits." Thesis, Poitiers, 2013. http://www.theses.fr/2013POIT2259/document.
Повний текст джерелаThis research belongs to the study of the ionization of aqueous solutions by electron beam (E.B.) as an advanced oxidation process for water treatment. The hydroxyl radical (•OH) and hydrated electron(eaq¯) are the two major active species produced from the ionization of aqueous solutions by high energy electron beam. It has been shown that the generation of additional radicals such as the sulphate radical (SO4•¯) and hydroxyl radical from the reaction of persulfate ion (S2O8¯) or hydrogen peroxide (H2O2) with the hydrated electron, improved the efficiency of this process towards the degradation and mineralization of organic pollutants in aquaeous solution. In the présent work, the degradation and mineralization of naphthalenesulfonate, benzenesulfonate and gallic acid were studied by electron beam irradiation alone and coupled with oxidants (S2O8¯, H2O2).In the absence of oxidant, an absorbed dose of 1,5 kGy leads to total elimnation of these pollutants. The presence of added oxidants usually reduces the radiation dose required. In addition, increasing oxidant concentration or applied dose had a beneficial effect towards the organic carbon removal. It was found that coupling E.B./S2O8¯ has more suitable than E.B./ H2O2 even in the presence of inorganic constituents. The results also highlighted the importance of dissolved oxygen in the system when mineralization is aimed. For each of the molecules studied, oxidation by-products resulting from hydroxylation and aromatic ring opening were identified
Li, YongChao. "DETOXIFICATION OF SELECTED CHLORO-ORGANICS BY OXIDATION TECHNIQUE USING CHELATE MODIFIED FENTON REACTION." UKnowledge, 2007. http://uknowledge.uky.edu/gradschool_diss/551.
Повний текст джерелаChakraborty, Sourav. "Molecular Probes for Biologically Important Molecules: A Study of Thiourea, Hydroxyl radical, Peroxynitrite and Hypochlorous acid." ScholarWorks@UNO, 2010. http://scholarworks.uno.edu/td/1132.
Повний текст джерелаWagner, Alec Thomas. "Fundamental Studies of Two Important Atmospheric Oxidants, Ozone and Hydroxyl Radical, Reacting with Model Organic Surfaces." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/45093.
Повний текст джерелаMaster of Science
Pan, Xiong. "Theoretical Studies of Atmospheric Water Complexes." PDXScholar, 1992. https://pdxscholar.library.pdx.edu/open_access_etds/1163.
Повний текст джерелаDeMatteo, Matthew P. "Computational investigations of hydroxyl radical addition to aromatics and alkenes in the presence of solvent, conformational preferences of dendrimers, and theoretical studies of arabinofuranosides and septanosides." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1180128001.
Повний текст джерелаPillar-Little, Elizabeth A. "MECHANISMS OF HETEROGENEOUS OXIDATIONS AT MODEL AEROSOL INTERFACES BY OZONE AND HYDROXYL RADICALS." UKnowledge, 2017. http://uknowledge.uky.edu/chemistry_etds/80.
Повний текст джерелаBrosse, Fabien. "Influence de la couche limite convective sur la réactivité chimique en Afrique de l'Ouest." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30324/document.
Повний текст джерелаThis thesis focuses on the influence of the convective and cloudy boundary layer on the chemical reactivity in West Africa. To answer this question, high resolution simulations (50m) are performed on the atmospheric model Meso-NH coupled to a detailed chemical scheme representing the gaseous and aqueous phases. This spatial scale allow to explicitly represent the spatial and temporal characteristics of turbulent structures. Thermals in the boundary layer are identified by a conditional sampling based on a radioactive-decay passive scalar. The turbulent transport influence on the redistribution of chemical species depends on the chemical lifetimes of these species. Spatial segregation is created within the convective boundary layer that increases or decreases the mean reaction rates between compounds. AMMA campaign field study, and more recently DACCIWA, are used to define dynamical and chemical forcing of two simulated environments. The first one is representative of a biogenic environment dominated by natural emissions of VOC. The second reproduces a moderately polluted typical urban area of the Guinean Gulf (Cotonou in Benin). For the sake of simplicity, simulations analysis are limited to the chemical reaction between isoprene and OH in the biogenic case, and the reaction between C>2 aldehydes and OH in the anthropogenic case. The convective boundary layer influence is studied at thermal and domain scale. This makes the connection with coarse resolution models for which a hypothesis of perfect and immediate mixing is made, neglecting the spatial variability of chemical species within a grid cell. The first results are based on the gaseous phase only. Cloudy development in the convective boundary layer only affects the vertical transport of chemical species. The simulations show that thermals are preferential reaction zones where the chemical reactivity is the highest. The top of the boundary layer is the region characterized by the highest calculated segregation intensities but of the opposite sign in both environments. In the biogenic environment, the inhomogeneous mixing of isoprene and OH in this zone leads to a maximum decrease of 30% of the mean reaction rate. In the anthropogenic case, the effective rate constant for OH reacting with aldehydes is 16% higher at maximum than the averaged value. The OH reactivity is higher by 15 to 40% inside thermals compared to the surroundings depending on the chemical environment and time of the day. Because thermals occupy a small fraction of the simulated domain, the impact of turbulent motions on the domain-averaged OH total reactivity reaches a maximum 9% decrease for the biogenic case and a maximum of 5% increase for the anthropogenic case. LES simulations including the aqueous reactivity reveal a significant decrease in OH mixing ratios associated to the presence of clouds. Consequently, isoprene and C>2 aldehydes mixing ratios increase at these altitudes
Wu, Hong. "Sulfate radical based ceramic catalytic membranes for water treatments." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2020. https://ro.ecu.edu.au/theses/2382.
Повний текст джерелаGallo, Inara Fernanda Lage. "Preparação e caracterização de fotocatalisadores heterogêneos de titânio e nióbio e avaliação do potencial de fotodegradação." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/59/59138/tde-05072016-152453/.
Повний текст джерелаNowadays, the development of new technologies for the treatment of water is urgent. In this context, the advanced oxidative processes (AOP) has been successful in the treatment of contaminants foundin industrial effluents and domestic sewage. In this work, we have studied an AOP, the heterogenousphotocatalysis, by means the synthesis of niobium and titanium mixedphotocatalysts, employing calcination temperature of 470 oC.The PNB000, PNB018, PNB030, PNB070, PNB099 and PNB100photocatalysts were synthetized, where the numbers show the percentage in mol of Nb2O5content in each of them. These photocatalytswere submitted to a second heat treatment to 800oC during 6 hours, and PNB000_01, PNB018_01, PNB030_01, PNB070_01 and PNB100_01 were obtained. The characterization of the photocatalysts was made by: analysis of the energy dispersive spectroscopy (EDS); the surface area determined by adsorption and desorption isotherms of nitrogen, BET; images of scanning electron microscopy (SEM); X-ray diffraction; thermal analysis (thermogravimetry and differential thermal analysis), determination of the band gap by diffuse reflectance.Their potential to be used as heterogeneous photocatalystsfor degradation of organic compounds was evaluated by means the determination of the photonic efficiency for hydroxyl radical production (OH)under radiation of UV-A lamp (15 W). The EDS analysis confirmed the composition in mol of TiO2 and Nb2O5 present in the synthesizedphotocatalysts. Surface area obtained by isotherms (BET) of PNB018 (161.7 m ²/g), PNB030 (130.8 m ²/g), PNB070 (150.5 m ²/g) were higher than TiO2 P25 (52.68 m ²/g). SEM images showed that these photocatalysts consist of nanoparticles. Another feature of the oxides with intermediate amount of moles of Nb2O5 (18, 30 and 70%) was the amorphous structure determined by X-ray diffraction. On the other hand, the oxides treated to 800 oC showed crystalline structures and X-ray patternscompletely different from TiO2 and Nb2O5, proving that the synthetized oxides are new materials.The band gap energy measurements showed significant differences when we compare TiO2 P25 (Egap 3.22 eV) and the PNB000 (Egap 2.90 eV). This allow us to conclude that thephotocatalysts synthesized by Pechini method require lower energy in order to have electronic transitions. The PNB070 photocatalyst, which has 70% in mols of niobium pentoxide, showed OHof 0.104 of the same order of magnitude of TiO2 P25 (OH0.134) and slightly smaller than the OH of Nb2O5.nH2O (OH 0.164). For this reason, we can assume that PNB070 has the same potential of the TiO2 P25 for organic compound photodegradation. The photocatalyststhat were submittedthrough a second heat treatment at 800 oC showed quantum efficiency of hydroxyl radical production values well below their original. For instance, PNB070_01 showed OHof 0.003. These results suggest that increased crystallinity can reduce the photocatalytic activity, or the amorphous structures of the photocatalysts of this work improve the electron transfer rates and the photocatalysis.
Holmes, Bryan J. "Oligomerization of Levoglucosan in Proxies of Biomass Burning Aerosols." ScholarWorks @ UVM, 2008. http://scholarworks.uvm.edu/graddis/111.
Повний текст джерелаBones, David Lawrence. "Liquid Aerosol Photochemistry." Thesis, University of Canterbury. Chemistry, 2008. http://hdl.handle.net/10092/1500.
Повний текст джерелаOladiran, Oladun Solomon, and Scott J. KIrkby. "Computational Studies of the Spin Trapping Behavior of Melatonin and its Derivatives." Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/asrf/2019/schedule/186.
Повний текст джерелаLallement, Audrey. "Impact des processus photochimiques et biologiques sur la composition chimique du nuage." Thesis, Université Clermont Auvergne (2017-2020), 2017. http://www.theses.fr/2017CLFAC066/document.
Повний текст джерелаIn the context of global warming, more precise knowledge of atmospheric processes is needed to evaluate their impact on the Earth radiative budget. Clouds can limit the increase of temperature but this retroaction is not well understood due to a lack of knowledge of cloud media (like organic fraction composition). From the beginning of atmospheric studies, only chemical, especially radical, reactions was taken into account. However microorganisms metabolically active were found in cloud water arising questions about their role as biocatalyst. They are able to use carboxylic acids as nutriments, to degrade radical precursor (like H2O2) and to survive oxidative stress. The aim of this work is to quantify the impact of photochemical and biological processes on cloud chemistry composition. First, the concentrations of •OH, the most reactive radical, were evaluated and the influence of microorganisms on the concentrations were studied. A new method was developed in artificial medial before direct quantification of steady state •OH concentration in atmospheric waters (rain and cloud waters). Concentrations ranged from 10-17 to 10-15 M and did not change in presence of microorganisms. These measures were lower than concentrations estimated by chemical atmospheric models. A possible explanation was an underestimation of the main sink of this radical (organic matter). To better characterize this fraction, simple aromatic compounds were identified in cloud waters, phenol was found in the 8 samples analyzed. To go further, we studied phenol degradation in detail. Enzyme transcripts involved in phenol degradation were present in cloud water samples showing in situ activity of native bacteria. 93% of tested cultural strains, isolated from cloud waters, were able to degrade phenol. To quantify the relative contribution of radical versus microbial processes allowing phenol degradation, we performed photo-biodegradation experiment with a model strain (Rhodococcus erythropolis PDD-23b-28). Our results showed that these two processes participated equally to phenol degradation, suggesting that microorganisms and radicals can be involved in atmospheric natural remediation
Kuhlmann, Rolf von. "Tropospheric photochemistry of ozone, its precursors and the hydroxyl radical a 3d-modeling study considering non-methane hydrocarbons /." [S.l.] : [s.n.], 2001. http://ArchiMeD.uni-mainz.de/pub/2001/0141/diss.pdf.
Повний текст джерелаXiao, Ai-Ying. "The central catechol-O-methyltransferase inhibitor tolcapone increases striatal hydroxyl radical production in L-Dopa, carbidopa treated rats." [S.l.] : [s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=965145298.
Повний текст джерелаBaasandorj, Munkhbayar. "Experimental and theoretical studies of the kinetics of the hydroxyl radical-initiated oxidation of oxygenated volatile organic compounds." [Bloomington, Ind.] : Indiana University, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3297937.
Повний текст джерелаTitle from dissertation home page (viewed Sept. 30, 2008). Source: Dissertation Abstracts International, Volume: 69-03, Section: B, page: 1537. Adviser: Philip S. Stevens.
Liljegren, Jennifer A. "Experimental and theoretical studies of the kinetics of the hydroxyl radical (OH)-initiated oxidation of volatile organic compounds." Thesis, Indiana University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3602969.
Повний текст джерелаThis research investigates the kinetics of the hydroxyl radical (OH)-initiated oxidation of several volatile organic compounds (VOCs) including ethanol, 3-methylfuran, and methyl ethyl ketone (2-butanone). Oxidation by OH is the dominant loss process for many biogenic and anthropogenic VOCs, making ambient concentrations of OH and the rate constants of OH + VOC reactions useful for determining the lifetime of various VOCs in the atmosphere. The rate constants of OH + VOC reactions are important for improving the accuracy of input parameters used in urban and regional air quality models which can be used to inform the development of air quality control strategies. The absolute rate constants for the reaction of OH with ethanol, 3- methylfuran, and methyl ethyl ketone (2-butanone) and, in some cases, their deuterated isotopomers have been measured as a function of pressure and temperature using discharge-flow techniques coupled with laser-induced fluorescence detection of OH. Theoretical studies of the potential energy surface for the various pathways in the OH + ethanol and OH + methyl ethyl ketone (2-butanone) reactions indicate a mechanism involving hydrogen-abstraction through a hydrogen-bonded pre-reactive complex. The experimental measurements of the rate constants and the kinetic isotope effect have been used in conjunction with the results of the theoretical studies to improve our understanding of the kinetics of these reactions.
Machairas, Alexandros 1980. "The UV/H2O2 advanced oxidation process in UV disinfection units : removal of selected phosphate esters by hydroxyl radical." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/29410.
Повний текст джерелаIncludes bibliographical references (leaves 96-97).
In this work, the issue of how to remove phosphate esters from drinking water is examined. From the various treatment processes available, the oxidation of phosphate esters through hydroxyl radical generated by the UV/H202 process applied at a UV disinfection unit was selected for evaluation. The second-order rate constants of the reactions of two phosphate esters, Tri(2-butoxyethyl) phosphate (TBEP) and Tri-2-chloroethyl phosphate (TCEP) , with hydroxyl radical were estimated from our experimental data to be 2.1000 M-1s-1 and 2 109 M-is-1 respectively A comprehensive kinetic model of the oxidation process was derived. Finally computer simulations were used to exhibit the potential of this treatment process and to examine the effects of pH, total carbonate species concentration, initial hydrogen peroxide dose, and light intensity on its efficiency. The results are not very encouraging when a UV unit designed for disinfection is used. For typical values of pH and total carbonate species (pH=8 and CT=5' 10-4 M) the 1 s order rate coefficients for removal of the phosphate esters are 6.3 10-4 (s-1) for TBEP and 6.3 10-5 (s-1) for TCEP. If higher light intensity is applied in the reactor (50 times higher), and initial hydrogen peroxide dose of 10-3 M and CT remains 5 10-4 M, the 1st order reaction rate coefficients become 2.9 10-2 (s-1) and 2.9-10-3 (s-1) for TBEP and TCEP respectively.
by Alexandros Machairas.
M.Eng.
Joshi, Prasad. "Isolation and reactivity of hydroxyl radical with astrochemically and atmospherically relevant species studied by Fourier transform infrared spectroscopy." Paris 6, 2012. http://www.theses.fr/2012PA066092.
Повний текст джерелаOH radicals play a fundamental role in the chemistry of interstellar media. The isolation and the characterization of the highly reactive species is challenging and represents an important prerequisite for reactivity studies that might be crucial in different fields such as astrochemistry and atmospheric chemistry. Different experimental approaches were tested to produce OH radicals. First of all, gaseous pure water was subjected to a microwave discharge. The species thus formed were condensed onto a cryogenic mirror maintained at 3 K and further characterized with a Fourier-transform IR spectrometer (FTIR). Under these conditions, radical recombination lead to the formation of a water-ice and the presence of OH radicals cannot be clearly established. Gaseous water was diluted into different rare gases (RG = He, Ne, Ar) prior to their introduction into the microwave discharge source. This approach allows to isolate and characterize OH radicals both in solid phase (RG = He) and in neon matrix (RG = Ne). Further reactivity experiments were carried out between these radicals and small species such as H2O, CO, NO, N2, O2, and CH4 in solid phase as well as in neon matrix