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1
Ohshiro, Takashi. "MICROBIAL SULFUR METABOLISM OF HETEROCYCLIC SULFUR COMPOUNDS." Kyoto University, 1996. http://hdl.handle.net/2433/78073.
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Ghosh, Supriyo. "Production of Volatile Sulfur Compounds from Inorganic Sulfur by Lactococci." DigitalCommons@USU, 2003. https://digitalcommons.usu.edu/etd/5493.
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Production of volatile sulfur compounds in cheese is associated with desirable flavors. The direct source of these compounds has been assumed to arise from the metabolism of methionine and cysteine. However, the methionine concentration in cheese rises above the amount found in casein during aging, suggesting that alternative sulfur sources are present in milk. This led us to hypothesize that lactococci may acquire sulfur from the inorganic sulfur pool of milk, in addition to methionine and cysteine, to generate volatile sulfur compounds during cheese ripening.
A turbidimetric method to determine total sulfate content in milk samples was developed. The average sulfate content of milk was determined to be ~49 mg/L ± 2.0 mg/L. The limit of detection of the test was ~2.5 mg/L in Tris buffer and ~10 mg/L in milk. Skim milk samples had significantly higher total sulfate content as compared to whole milk samples.
Transport of sulfate by three strains of Lactococcus sp. was studied after we determined that milk had small, but measurable amounts of inorganic sulfate. A decrease in the environmental pH increased sulfate transport. The maximum transport occurred during exponential cellular growth phase. All strains tested had the ability to transport much more sulfate than is native in milk.
The last phase of study was to determine the metabolic fate of sulfate. Incorporation of radio-labeled sulfate into cellular protein was studied by two-dimensional gel-electrophoresis of crude cellular lysate followed by auto-radiography. Production of volatile sulfur compounds from inorganic sulfur was determined with analysis of the head space gas with gas chromatography and scintillation counting. The incorporation of radio-labeled sulfur from sulfate was not detected in proteins on two-dimensional gels. Detectable volatile sulfur compounds were found only in the case of gas chromatographic analysis of ML3 head space. However, radio-labeled volatile sulfur was detected in the head space of all the three strains with scintillation counting. This study defined that lactococci can fix inorganic sulfur into volatile sulfur compounds in small amounts.
3
Matuska, Vit. "Five-membered sulfur-nitrogen ring compounds." Thesis, St Andrews, 2009. http://hdl.handle.net/10023/828.
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Padden, Amena Nicole. "Microbial degradation of organic sulfur compounds." Thesis, King's College London (University of London), 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264989.
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Persson, Sten. "Volatile sulfur compounds in periodontal pockets." Umeå, Sweden : University of Umeå, Dept. of Oral Microbiology, 1993. http://catalog.hathitrust.org/api/volumes/oclc/35846617.html.
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Mundoma, Claudius. "Sulfur chemistry st[r]ucture and reactivity of substituted thioreas and aminothiols of physiological importance /." Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=1067.
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Walfort, Bernhard. "Novel dianionic sulfur ylides and related compounds." Doctoral thesis, [S.l.] : [s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=96422187X.
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Kim, Kyoung Mahn. "Novel radical reactions involving sulfur-containing compounds." Thesis, University College London (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342258.
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Wu, Kanning. "NMR Analysis of Sulfur Compounds in Petroleum." TopSCHOLAR®, 1992. https://digitalcommons.wku.edu/theses/3004.
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The speciation and quantification of organic sulfur forms in fossil fuel is an area of research. This thesis describes an NMR method which offers potential for identifying and possibly quantifying both nonvolatile and volatile sulfur forms in fossil fuels. The method is based on the methylation of sulfur compounds to form methyl sulfonium salts:
RSR + Ch3I --> (R2S+-Ch3)I~
We propose to apply this chemistry to the analysis of sulfur functions in fossil fuels. The sulfur functions are methylated using 13C-enriched methyl iodide. The products are then analyzed by 13C NMR spectroscopy to establish the chemical shifts of the added methyl carbons. The chemical shifts are then correlated against those of known sulfonium salts.
10
Rodriguez, Francisco. "Capillary Zone Electrophoresis Studies of Sulfur Containing Compounds." TopSCHOLAR®, 1998. http://digitalcommons.wku.edu/theses/317.
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Up to this point in time, complex mixtures of tertiary sulfonium ions have been separated or analyzed employing conventional methods like HPLC or NMR procedures. In this thesis the researcher presents a new approach, the use of Capillary Zone Electrophoresis (CZE) for the analysis of these types of ions as well as the closely related thiophenium ions. CZE offers an unprecedented advantage in that separations can be employed for speciation or quantitation of complex mixtures by using the appropriate standards or specific detectors. For the study, model sulfonium and thiophenium ions were used to determine the feasibility of the separation and to optimize conditions. Once conditions were established, a complex mixture of these ions isolated from a petroleum sample was analyzed. Furthermore, the chiral separation of sulfonium and thiophenium ions was explored using CZE. Again, it is for first time that CZE is used for the chiral analysis of these ions. The separation involves the use of a chiral resolving agent, in this case native or derivatized |3-cyclodextrins, added to the separation buffer. Differentiated interactions of the sulfonium ions with the cyclodextrin affords chiral recognition and thus separation. A final topic of study was the chiral analysis of O-methylated sulfoxides, (alkoxysulfonium ions) employing conditions analogous to those used for the chiral analysis of sulfonium ions.
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Reut, Stepan. "Selective adsorption of sulfur compounds from hydrocarbon mixtures." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0021/MQ58008.pdf.
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Namutebi, Mariam. "Asymmetric Sulfur Ylide Mediated Epoxidation of Carbonyl Compounds." Thesis, University of Bristol, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520213.
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Bull, Andrew E. A. "Synthesis and characterisation of sulfur containing boron compounds." Thesis, University of Bristol, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404434.
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Kanagawa, Takahiro. "DEVELOPMENT OF MICROBIAL DEODORIZING PROCESSES FOR SULFUR COMPOUNDS." Kyoto University, 1990. http://hdl.handle.net/2433/78233.
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Wasiowych, Christine Dara. "A study of nickel-sulfur catalysis." Thesis, The University of Sydney, 1994. https://hdl.handle.net/2123/26674.
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The [Ni(sacsac)PBu3C1]/A1EtnCl3_n (where n = 1, 2) catalyst system is investigated (Section I) by studying the isomerisation of 2,3-dimethyl-1-butene. Three parameters were varied - the temperature, and the concentrations of the nickel precursor and aluminum cocatalyst species. The temperature studies illustrated subtleties in the reaction, such as the induction period observed for the isomerisation experiment carried out at -10 °C. The isomerisation data was simulated using the SCoPfit computer program, and rate coefficients were calculated, and a kinetic model was proposed. The simulation study indicates that two active catalyst species are generated from the nickel precursor and cocatalyst species.
Section II of this thesis investigates the electrochemistry of the [Ni(sacsac)2] complex. The iNi(II/I) couple is electrochemically reversible (AEp = 88 mV) in the absence of water and light. It has been established that [Ni(sacsac)2] does not react with CO, Mel, and dodecanethiol. The results show that the electrogenerated [Ni(sacsac)2]' monoanion reacts with C0, C02, MeI, dodecanethiol, water and light.
The crystal and molecular structures of the compounds [Ni(ButacButac)2],(Ia), [Ni(ButsacButac)2], (Ib), and [Ni(ButsacButsac)2], (Ic), have been determined and are presented in Section HI. Compound (Ia), [Ni(ButacButac)2], crystallises as monoclinic crystals, space group P21/c, with a 10.372(2), b 10.935(2), and c 11.773(3) A, B 113.35(2) and Z = 2. The structure was refined to R 4.54 %, RW 5.05 % with 1599 reflections with I > 256(1). The N iO4 unit is rigorously planar, with Ni-Oave 1.860, ONiO 94.5(1) and 180.0(0) °, O---O (intraligand "bite") 2.685, OmO (interligand) 2.484 A. Compound (Ib)[Ni(ButsacButac)2], crystallises as monoclinic crystals, space group P21/a, with a 12.413(2), b 10.244(3), c 19.900(5) A, B 101.99(2) and Z = 4. The structure was refined to R 5.48 %, Rw 6.04 % with 3449 reflections with I > 310. The Ni02S2 unit is very close to planar, with the oxygen and sulfur donor atoms of opposite ligands mutually trans and Ni-Oave 1.860, Ni—Save 2.131, SNiO 95.5 °, ONiO 82.7 ° and SNiS 86 °, S---S 2.908, 0-0 2.462 and S---O (intraligand "bite") 2,972 A. Compound (Ic), [Ni(ButsacButsac)2], crystallises as monoclinic crystals, space group P21/c, with a 9.750(2), b 11.741(2), c 11.603(2) A, [3 9938(2) and Z = 2. The structure was refined to R 2.89 %, Rw 3.98 % with 1043 reflections with I > 310. The NiS4 unit is rigorously planar, with Ni-Save 2.150, SNiS 82.9 and 97.1 °, S---S (interligand) 2.846 and S---S (intraligand "bite") 3.222 A.
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Chiu, Winnie Wai Hang. "Metal complexes with sulfur and selenium donor ligands /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202009%20CHIU.
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Frank, Aaron J. "Small, oxygenated sulfur compounds : a neutralization-reionization mass spectrometry, ab initio/RRKM, and flowing pyrolysis study /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/11610.
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Jessop, Philip Gregory. "The syntheses and reactions of carbonyl(phosphine)(thiolator)ruthenium(II) complexes." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30928.
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The chemistry of homogeneous transition metal systems offer parallels to the reactions on the surfaces of industrial hydrodesulphurization catalysts. The reactions of several ruthenium complexes with sulphur-containing reagents are described, with an emphasis on the kinetics and mechanisms thereof. The complex Ru(CO)₂(PPh₃)₃ (2), for example, reacts quickly with thiols and disulphides, producing cct-RuH(SR)(CO)₂(PPh₃)₂ (9) and cct-Ru(SR)₂(CO)₂(PPh₃)₂ (14), respectively, although 2 fails to react with unstrained thioethers. Reactions of the related complex Ru(CO)₂(PPh₃)(dpm) (dpm=Ph₂PCH₂PPh₂) are complicated by the lability of all of the three different ligands.
The two dihydrides cct-RuH₂(CO)₂(PPh₃)₂ (3) and RuH₂(dpm)₂, as a cis/trans mixture (7), react with thiols to produce the hydrido-thiolato complexes 9 and RuH(SR)(dpm)₂ (13). respectively. The mechanisms appear to depend on the basicity of the hydride ligands; the more basic dihydride, 7, is probably protonated by the thiol, giving an unobserved molecular hydrogen intermediate, while 3 reacts by slow reductive elimination of H₂. The same rate constant, rate law, and activation parameters are found for the reaction of 3 with thiols, CO or PPh₃. The reaction of 3 with RSSR produces mostly 9, with small amounts of 14.
The complete characterization of several members of the series 9 and 14 is described, including the crystal structure of the p-thiocresolate example of each. The reactions of 9 with other thiols, P(C₆H₄pCH₃)₃, CO, RSSR, HCl, PPh₃, and H₂, are also reported. The first three of these reactions share the same rate law and rate constant, the common rate determining step probably being initial loss of PPh₃. Some equilibrium constants for the exchange reactions of 9d (R=CH₂CH₃) with other thiols were tetermined, the Keq values increasing with the acidity of the incoming thiol.
The mercapto hydrogens of 9a and 14a (R=H) exchange with the acidic deuterons of added CD₃OD. The hydridic and ortho-phenyl hydrogens exchange more slowly, presumably by intramolecular processes.
Complex 14b (R=C₆H₄pCH₃) is unstable in the presence of light, exchanges phosphines rapidly with added P(C₆H₄pCH₃)₃, exchanges thiolate groups with added thiols, and is converted by high pressures of H₂ to a mixture of 9b and 3.
Intermediates proposed for the mechanism of the thiol exchange reactions of 9 and 14 contain two or three thiolate groups sharing a proton. A related complex, [Ru(CO)₂(PPh₃)(μSEt)₂(μ₃SEt)Na(THF)]₂, which contains three thiolate groups on a ruthenium centre sharing a sodium cation, was isolated from the reaction of cct-RuCl₂(CO)₂(PPh₃)₂ with sodium ethanethiolate. In acetone, 9b and 14b can be formed cleanly from cct-RuHCl(CO)₂(PPh₃)₂ and cct-RuCl₂(CO)₂(PPh₃)₂, respectively, by reaction with p-thiocresolate.
Complex 3 or cheaper analogues could be used as catalysts for the reduction of disulphides by H₂, or as recyclable reagents for the non-oxidative extraction of thiols from thiol-containing mixtures such as oil fractions. The chemistry described above will help to guide future researchers to systems that more closely parallel the processes occurring on the surfaces of industrial hydrodesulphurization catalysts.Science, Faculty of
Chemistry, Department of
Graduate
19
Heer, Kaur Parmjit. "π-acid catalysed cyclisations to generate sulfur containing compounds." Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/4886/.
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Complex scaffolds are readily accessed via Gold and Platinum π-acid catalysis starting from simple precursors. These precious metal π-acids are used to generate sulfur ylides which undergo rearrangement to interesting sulfur containing compounds analogous to those formed via diazo-chemistry. In this thesis the utility of these π-acids to generate sulfur ylides will be discussed by: 1) The in situ generation of α-carbonyl carbenoids directly from alkynes avoiding “sacrificial functionality”; 2) Achieving different regiochemical outcomes using electronically biased alkyne systems; 3) Designing domino reactivity using simple functional groups. Recent developments involve the use of ynamides as regio-directing agents for site specific oxygen-transfer from a suitable oxidant to form the α-oxo-gold-carbenoid functionality. These carbenoids mimic the reactivity observed by decomposition of diazo-compounds with non-precious transition metals. A new gold catalysed intramolecular rearrangement of ynamide tethered-sulfoxides have led to highly complex products. Designing the starting sulfoxide substrates to allow tandem cyclisation reactions have led to formation of polycyclic sulfur heterocycles which are close to sulfur analogues of known biologically active compounds.
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Du, Junyi. "X-ray crystallographic studies of sulfur/selenium heteroatom compounds." Thesis, University of St Andrews, 2016. http://hdl.handle.net/10023/8984.
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The major aim of research reported on this thesis uses X-ray crystallography to investigate the structural features of a series of pentafluorosulfuranyl (SF₅) containing aromatic compounds, chalcogen amides, 2,4-diaryl-1,3-selenazoles and 2,4-diaryl-1,3-chalcogen azoles bearing SF₅ group and organo phosphorus-chalcogen macrocycles incorporationg double OP(S)SC[sub]n or OP(Se)SeC[sub]n scaffolds. The basic theory of crystallography is introduced in Chapter 1, followed by a general discussion on pentafluorosulfuranyl (SF₅) containing heteroatom compounds and sulfur/selenium heterocycles in Chapter 2. Ten pentafluorosulfuranyl (SF₅)-containing aromatic compounds have been studied crystallographically in Chapter 3. All S-F bond lengths in these compounds are very similar [1.571(3) to 1.618(3) Å and 178.5(3) to 180.0° for the C-S-F(ax) bond] and the angles of two adjacent F(eq) is approximate to 90°. The intramolecular C[sub](aryl)-H···F(eq) and intermolecular C[sub](aryl)-H···O/N/F/Cl interactions, and π-stacking interactions are observed in the packing frameworks. X-ray crystal structure analysis reveals that in the structures of 2,4-diaryl-1,3-selenazoles in Chapter 4, the five-membered N-C-Se-C-C rings have either planar or near-planar conformations, and exhibit a series of the intramolecular and intermolecular C-H∙∙∙O/N/Se/Br/Cl) interactions and π-stacking interactions. The crystal structures of 2,4-diaryl-1,3-chalcogen azoles with both a pentafluorosulfuranyl (SF₅) group and a five-membered N-C-Se-C-C ring have been investigated in Chapter 5. A diverse picture of molecular configuration and intramolecular/intermolecular C-H∙∙∙N/Se/S and π-stacking interactions information are disclosed in selenamide, thiamides, 1,3-selenazoles and 1,3-thiazoles. Nine organo phosphorus-chalcogen macrocycles with nine- to fifteen-membered ring incorporating double OP(S)SC[sub]n or OP(Se)SeC[sub]n scaffolds have been discussed crystallographically in Chapter 6. The similar intramolecular and intermolecular C-H∙∙∙O, C-H∙∙∙S or C-H∙∙∙Se interactions are observed to lead to the similar packing networks.
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Jain, Manish. "Separation of sulfur compounds from FCC gasoline by pervaporation." Thesis, IIT Delhi, 2016. http://localhost:8080/xmlui/handle/12345678/7081.
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Sun, Chaode. "Syntheses and reactivities of [pi]-electron rich phosphorus-nitrogen and sulfur-nitrogen ligands." HKBU Institutional Repository, 1999. http://repository.hkbu.edu.hk/etd_ra/140.
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Wu, Shu-Pao. "Iron-sulfur cluster biosynthesis. Iron-sulfur cluster transfer from holo ISU and ISA to apo ferredoxin." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1078866123.
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Thesis (Ph. D.)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains xx, 161 p.; also includes graphics Includes bibliographical references (p. 153-161). Available online via OhioLINK's ETD Center
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Laffosse, Miguel Diaz. "Stereoselective carbon-carbon bond formation via sulfur stabilized carbanions." Thesis, Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/27171.
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Hatcher, Jancie Stinecipher. "Synthesis, characterization, and monolayer formation of sulfur-substituted tetraphenylporphyrins." Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/29977.
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Myers, Samuel. "Electrochemical Detection of Aliphatic Sulfur Compounds in Liquid Coal Extracts." TopSCHOLAR®, 1994. http://digitalcommons.wku.edu/theses/945.
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The presence of sulfur compounds in coal is a serious environmental problem that affects the coal industry. This problem is due to the fact that organic sulfur is not separated or removed during any physical cleaning process. Organic sulfur is removed only during a more costly chemical desulfurization process. The kinds of organosulfur compounds in coal are generally known, but the quantity of each type of compound and the distribution of these compounds throughout the coal matrix has not been studied extensively. The objective of this research was to investigate the more reactive and chemically labile organosulfur compounds in liquid coal extracts. Organosulfur compounds such as sulfides, aliphatic thiols, and disulfides were studied using reverse phase HPLC with electrochemical detection in a acetonitrile/water mobile phase. Coal samples IBC 101 and IBC 105 were extracted with THF and hexane. The liquid coal extracts were fractionated using a simple chromatographic technique. The fractionated extracts were then analyzed using reverse phase HPLC with UV detection, reverse phase HPLC with EC detection, infrared spectroscopy, and selected chemical tests. From the data collected, one can conclude that THF and hexane solvents did extract organosulfur species that were detectable with UV and electrochemical methods. THF was found to be a better extraction solvent as compared to hexane. THF extraction resulted in an enrichment of the organosulfur compounds in the coal samples extracted. The chemical reaction for organosulfur compounds was positive in all fractionated samples collected, while IR analysis was negative or inconclusive. Reverse phase HPLC with EC detection appears to be an ancillary technique that has the potential to provide some pertinent information about organosulfur compounds in liquid coal extracts.
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Yuen, Yue Tai. "Trithiazyl trichloride in the synthesis of sulfur-nitrogen heterocyclic compounds." Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362732.
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Winn, Caroline Louise. "Synthesis of sulfur compounds and their use in asymmetric synthesis." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621078.
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Chen, Yiding. "Synthesis of sulfur-containing organic compounds : sulfones, sulfonamides and benzoisothiazoles." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:92038d85-0597-4db0-8e56-0a32c671a655.
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This thesis documents the development of novel methodologies for access to sulfur-containing compounds, including sulfones, sulfonamides and benzoisothiazoles. Chapter 1 provides an overview of the applications and the synthesis of sulfonyl-containing compounds. A comprehensive introduction to the development of sulfur dioxide surrogates and their applications in transition metal-catalysed organic chemistry is given. Chapter 2 describes the development of a one-step copper(I)-catalysed sulfonylative Suzuki-Miyaura cross coupling reaction. A wide range of aryl and alkenyl boronic acids are coupled with aryl and alkenyl iodides to give the corresponding sulfones. A two-step one-pot sulfination/derivatisation method was also developed, allowing access to compounds including β-hydroxy sulfones, sulfonamides and sulfonyl fluorides. Chapter 3 illustrates a one-step copper(II)-catalysed sulfonamide synthesis using boronic acids, amines and SO2. Various aryl and alkenyl boronic acids as well as amines and anilines are compatible, including active pharmaceutical ingredients such as amoxapine and desloratadine. Chapter 4 details an aryne-based selective formation of substituted benzoisothiazoles. Different substitution pattern of the aryne precursor and the thiadiazole are employed, with the target heterocycles being obtained in good to excellent yields. Chapter 5 summarises the research and the future work. Chapter 6 documents the experimental procedures and data.
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Koyama, Daisuke. "Ultrafast photochemical reaction dynamics of aromatic sulfur compounds in solution." Thesis, University of Bristol, 2017. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.730850.
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Leung, Hoitung Terry. "Chemistry of deca- and dodeca-closo-borate bearing three exopolyhedral sulfur substituents." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1092772114.
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Thesis (Ph. D.)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains xvii, 168 p.; also includes graphics (some col.) Includes bibliographical references (p. 164-168). Available online via OhioLINK's ETD Center
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Witek, Rachel M. "Studies in synthetic methodology routes to sulfur- and nitrogen-containing compounds /." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0011359.
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Martins, Emanuel. "X-ray spectroscopic study of the electronic structure of sulfur compounds." Thesis, Queen Mary, University of London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283717.
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Sokmen, Munevver. "Studies of the metal ion-catalysed oxidation of heterocyclic sulfur compounds." Thesis, Sheffield Hallam University, 1997. http://shura.shu.ac.uk/20384/.
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Chemical oxidation by hydrogen peroxide is used for the treatment of hazardous organic materials present at low concentrations in contaminated soil and water. A knowledge of the oxidation of thiophene and its derivatives, with particular reference to oxidative destruction and the identification of intermediate oxidation products would be useful for a deeper understanding of reaction mechanisms in waste treatment and the optimization of conditions. In this thesis, the oxidation of thiophenes, namely thiophene and 2- and 3-methylthiophene, with hydrogen peroxide and catalyst systems, e.g. Fenton's reagent, Gif systems and titanium dioxide-assisted photocatalytic oxidations, all of which may involve the formation of free radicals, e.g. the hydroxyl radical (HO-), has been studied. Fenton-related catalyst systems, mixtures of iron salts (and sometimes also with copper salts) and hydrogen peroxide, have been suggested in the literature and their reactions with thiophenes have been investigated. Additionally, other catalytic systems that have also been suggested in the literature as having potential have been studied. The oxidation of thiophene derivatives with Fenton-like reagents involving a combinations of hydrogen peroxide with other metal salts including vanadium(IV), titanium(III), copper(I) and copper(II) have been explored, since all of these systems appear to form hydroxyl radicals. Further Fenton-related oxidations of reaction intermediates have been carried out in order to help understand whether the oxidation products described are derived directly from the original compound or from further oxidation of a reaction intermediate. The progress of the oxidation reactions was followed by chromatographic analysis, using Gas Chromatography-Mass Spectrometry and High Performance Liquid Chromatography, so as to establish the nature of the oxidation products and the possible reaction pathways. Components of the mixtures were identified by comparison with commercially available products or synthetic standards. Oxidation reactions were monitored over set time intervals and the amounts of residual thiophenes were determined. In all of the oxidation reactions investigated, Fenton-related and Fenton-like, heteroaromatic ring destruction was observed, together with the formation of small amounts of hydroxylated ring products and dimeric structures. The oxidative destruction of thiophenes was successfully achieved with the above catalyst systems in the presence of excess hydrogen peroxide. Recent literature has questioned the formation of hydroxyl radicals in Fenton-related systems, and in order to contribute to the debate regarding the oxidizing species responsible for the destruction of each of the thiophenes, the oxidation reactions have been carried out in the presence of a complexing agent such as ethylenediaminetetraacetic acid (EDTA), and a radical trapping reagent 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), respectively. Evidence of radical trapping was observed. Gif chemistry may involve the formation of high oxidation state iron complexes rather than free radicals. The oxidation of thiophenes was carried out using Fenton's reagent under Gif conditions and the results were compared with those from conventional Fenton and related conditions, to determine whether free radical species are involved in the latter. Radical derived products were again observed. Titanium-catalysed photooxidation has also formed part of this study to determine the nature of intermediate products which might be similar to those from Fenton-catalysed systems. For these reasons, the photocatalytic oxidation of 2-methylthiophene was studied in aqueous solution and the reaction was conducted in the presence and absence of titanium dioxide under an oxygen atmosphere. A similar range of radical derived products was found as in the conventional Fenton and related systems.
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Zhu, Lei. "Aqueous phase reaction kinetics of organic sulfur compounds of atmospheric interest." Diss., Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-11172004-142820/unrestricted/zhu%5Flei%5F200412%5Fphd.pdf.
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Thesis (Ph. D.)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2005.Davis, Douglas, Committee Member ; Huey, Greg, Committee Member ; Nenes, Athanasios, Committee Member ; Weber, Rodney, Committee Member ; Whetten, Robert, Committee Member ; Wine, Paul H., Committee Chair. Includes bibliographical references.
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Lentz, Nicolas. "Metallylene-sulfur compounds : synthesis, characterization and applications in coordination and catalysis." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30274/document.
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Ce travail présente la synthèse de ligands mixtes germylène-sulfoxyde qui ont été utilisés en chimie de coordination avec plusieurs métaux de transitions et finalement appliqués en catalyse de transfert d'hydrogène. Une seconde partie de ce travail est axée sur la synthèse de nouveaux métallylènes stabilisés par un sulfonimidamide qui ont été appliqués en catalyse de polymérisation. Le premier chapitre présente l'état de l'art des germylènes avec leurs synthèses, modes de stabilisations et finalement leur chimie de coordination et leurs applications en catalyse. Les sulfoxydes seront aussi décrits pour leur application en tant que ligands hémilabiles. Le second chapitre décrit la synthèse de ligands germylène-α-sulfoxide avec une diversité structurale (cyclohexyle, tBu, tolyle..) et avec différents degrés d'oxydation du souffre (thioéther, sulfoxyde et sulfone). La chimie de coordination a permis la synthèse de complexes bis-germylène du groupe IV, bidentes du ruthénium ainsi que monodentes du ruthénium. Le troisième chapitre présente l'extension de la méthodologie à la formation de ligands germylène-β-sulfoxide. L'influence du groupement espaçant les deux entités sur la chimie de coordination a été étudiée et montre la formation de complexes bidentates du groupe IV. La coordination du ruthénium a mené à la surprenante synthèse d'un complexe bis-ruthénium caractérisé par diffraction des rayons X. Finalement, la nouvelle architecture a permis d'obtenir des complexes de nickel (0) dont une structure avec des ligands carbonyles permettant une comparaison TEP. Le chapitre quatre présente la synthèse de nouveaux ligands, analogues des amidinates, pour la stabilisation des métallylènes avec un atome central soufré. L'effet apporté sur les métallylènes par ces nouveaux ligands sulfonimidamides a été étudié par calcul DFT. Le dernier chapitre est centré sur l'application de plusieurs complexes de ruthénium en catalyse de transfert d'hydrogène avec plusieurs substrats carbonylés. L'utilisation de stannylènes stabilisés par des ligands sulfonimidamides a été étudiée en catalyse de polymérisation de la ε-caprolactoneThis work concerns the synthesis of mixed germylene-sulfoxide ligands that were involved in coordination chemistry with several transition metals and finally applied in hydrogen transfer catalysis. In a second part, the synthesis of new metallylenes stabilized by a sulfonimidamide group was develop, which were applied in polymerization catalysis. The first chapter is centered on the state of the art of germylenes with their synthesis, their stabilization and finally their coordination chemistry and applications in catalysis. Sulfoxides will also be described for their potential as hemilabile ligands. The second chapter describes the synthesis of germylene-α-sulfoxide ligands as structurally tunable structures (cyclohexyl, tBu, tolyl..) and with different oxidation states of the sulfur atom (thioether, sulfoxide and sulfone). The coordination chemistry led to the formation of bis-germylene group IV complexes, bidentate-ruthenium and monodentate ruthenium complexes. The third chapter shows the extension of the methodology to the formation of germylene-β-sulfoxide ligands. The influence of the spacer between the two entities on the coordination chemistry was studied and shows the formation of bidentate group IV complexes. Coordination to ruthenium led to obtain a surprising bis-ruthenium complex characterized by X-ray diffraction analysis. Finally, the novel architecture allowed to obtain two nickel (0) complexes, one of them including carbonyl ligands permitting a TEP comparison. The fourth chapter is centered on the synthesis of new ligands, analogue of amidinate substituents for metallylene stabilization with a central sulfur atom. The effect brought to the metallylene center by the sulfonimidamide was studied by DFT calculations. The last chapter concerns the application of several ruthenium complexes in hydrogen transfer reaction with various carbonyl compounds. The use of sulfonimidamide stannylenes was also investigated in polymerization catalysis of ε-caprolactone
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Björk, Malin. "Synthesis of sulfur and seleniumn heterocycles, including derivatives of imidazopyridine and benzimidazole /." Stockholm, 2005. http://diss.kib.ki.se/2005/91-7140-597-6/.
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Blyth, Debra F. "Some studies on the formation and interconversion of iron-sulfur nitrosyl complexes." Thesis, University of St Andrews, 1996. http://hdl.handle.net/10023/15193.
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Studies on the effect of substituting iron(III) for iron(II) or nitrate for nitrite in the reaction of cysteine with iron(II) salts and nitrite with and without sodium ascorbate present demonstrated the formation of the tetranuclear Na[Fe4S3(NO)7] complex when iron(III) is substituted for iron(II), albeit in smaller yield; but no iron-sulfur-nitrosyl clusters were detected when nitrite was replaced with nitrate. Similarly in the case of reaction of methionine with iron(II) salts and nitrite in the presence of sodium ascorbate, the dinuclear complex Fe2(SMe)2(NO)4 is formed in reduced yield when iron(III) is substituted for iron(II) and no iron-sulfur-nitrosyl complexes are detected when nitrite is replaced with nitrate. The effect of pH on the reactions of cysteine and methionine with iron(II) salts and nitrate, with and without sodium ascorbate present in the case of cysteine, were studied. The cysteine reactions showed that in the presence of sodium ascorbate, the yield of Na[Fe4S3(NO)7] fell slightly as pH was decreased due to formation of the less soluble ascorbic acid from acidification of sodium ascorbate. At very low pH both cysteine reactions with and without sodium ascorbate present did not yield Na[Fe4S3(NO)7] due to the formation of nitric oxide from nitrite, which would rapidly oxidise to give nitrogen dioxide, and to the instability of the Na[Fe4S3(NO)7] complex itself at very low pH. The dinuclear complex Fe2(SMe)2(NO)4 is very stable to conditions of low pH but its formation at very acidic conditions was hindered, again due to the formation of nitric oxide from nitrite. A range of iron-sulfur containing amino acid complexes of the general type [Fe3o(amino acid)6(H20)3]X7, were synthesised and their reactions with nitrite studied. In the presence of sodium ascorbate, when the amino acid is methylcysteine, both [Fe4S3(NO)7]' and Fe2(SMe)2(NO)4 were isolated after reaction with nitrite. However no identified iron-sulfur-nitrosyl complexes could be detected when the amino acid was methionine. In the absence of sodium ascorbate both the methylcysteine and methionine complexes yielded a range of unidentified complexes which infra-red spectroscopy demonstrated absorbed strongly in the nitrosyl stretching region and it was postulated that the species observed were inorganic nitrosyl complexes. FTIR analysis of Fe4S4(NO)4 in the polar coordinating solvents THF, DMF and DMSO demonstrated conversion to [Fe4S3(NO)7]−. No such conversion was observed using the solvents diethyl ether or dichloromethane. An intermediate species was observed in THF and DMSO using FTIR spectroscopy which was postulated to be a [Fe(solvent)6][Fe4S4(NO)4]2 complex. Another peak observed in the latter stages of the conversion was believed to be that of a dinuclear Fe(SR)2(NO)4 type complex. ESR analysis of Fe4S4(NO)4 in THF and DMSO however demonstrated formation of a mononuclear species of type [Fe(NO)2(X)2]n+. Thus in the dilute solutions required for ESR analysis, mononuclear species of the type [Fe2(NO)2(X)2]n+ are favoured but in the more concentrated solutions needed for FTIR analysis polynuclear species of the type [Fe4S4(NO)4] are predominant.
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Ciaffoni, Luca. "Laser spectroscopy for the detection of volatile sulfur-containing compounds in breath." Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.534154.
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Evans, Alan. "Reactions of sulfur with unsaturated compounds to form extreme pressure oil additives." Thesis, Teesside University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.411295.
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Grabarczyk, Daniel Ben. "Molecular characterisation of bacterial proteins that interact with sulfur or nitrogen compounds." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:b6b3e3fd-620f-467d-b063-01311fa7a9a2.
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Many bacteria use inorganic nitrogen and sulfur compounds for energy metabolism. These compounds are often toxic and so bacteria must adapt to survive their deleterious effects. Bacteria use specific proteins in order to metabolise, sense and detoxify these compounds. In this thesis protein interactions with inorganic nitrogen and sulfur compounds are examined at the mechanistic level. Intermediates in the Sox sulfur oxidation pathway are covalently attached to a cysteine on the swinging arm of the substrate carrier protein SoxYZ. An interaction between the Sox pathway enzyme SoxB and the carrier protein SoxYZ is demonstrated. A crystal structure of a trapped SoxB-SoxYZ complex at 3.3 Å resolution identifies two sites of interaction, one between the SoxYZ carrier arm and the SoxB active site channel and the other at a patch distal to the active site. The presence of a distal interaction site suggests a mechanism for promiscuous specificity in the protein-protein interactions of the Sox pathway. Using biophysical methods it is shown that SoxB distinguishes between the substrate and product forms of the carrier protein through differences in interaction kinetics and that the carrier arm-bound substrate group is able to out-compete the adjacent C-terminal carboxylate for binding to the SoxB active site. The thiosulfate dehydrogenase TsdA has an unusual His/Cys coordinated heme. TsdA catalyses oxidative conjugation of two thiosulfate molecules to form tetrathionate. Mass spectrometry and UV/visible spectroscopy are used to identify an S-thiosulfonate reaction intermediate which is covalently attached to the cysteine heme ligand. A catalytic mechanism for TsdA is proposed using a crystal structure of TsdA at 1.3 Å resolution alongside site-directed mutagenesis of active site residues. Nitric oxide is produced by the mammalian immune response to kill bacterial pathogens. Part of the killing mechanism occurs through the reaction of nitric oxide with protein-bound iron-sulfur clusters. However, the same type of reaction is also exploited by nitric oxide-sensing bacterial proteins. An infrared spectroscopy approach is developed to detect the products of iron-sulfur protein nitrosylation. Using this methodology it is shown that the presence of trace O2 strongly impacts which products are formed in these nitrosylation reactions. These observations are of physiological relevance because bacteria are often exposed to NO under aerobic conditions during an immune response.
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Berlanga, Jesus Alejandro. "Kinetic Modeling of the Atmospheric Photooxidation of Reduced Sulfur and Nitrogen Compounds." TopSCHOLAR®, 2018. https://digitalcommons.wku.edu/theses/2686.
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Atmospheric aerosols encapsulate a wide variety of particles with different compositions, sizes and sources of origin. They also directly and indirectly affect climate by their interactions with sunlight, clouds, atmospheric chemical species, and even other suspended particles. To understand the atmospheric aerosol processes and the effects they have in global and regional climate is of utmost importance for the future establishment of environmental regulations and emission policies that affect aerosol precursor compounds in an effective and beneficial manner. In particular, aerosols are known to be formed from emissions from human activities, such as fossil fuel burning, agriculture, or concentrated animal feeding operations (CAFOs). Secondary organic aerosols (SOA) constitute a type of atmospheric aerosols that are formed from the atmospheric oxidation of organic compounds that are released from various sources into the atmosphere. Due to the complexity of the atmosphere and variability of its conditions, the direct study of SOA formation is a challenging task, but the implementation of atmospheric chamber facilities to study aerosol formation and growth under controlled conditions has provided a way to study the formation and growth of SOA. However, chamber experiments cannot study specific reactions or individual compounds from the aerosol formation mechanisms in isolation, they can only provide insight on what is produced and what it is produced from, and under what conditions. Thus, kinetic modeling of the mechanisms of gas-phase atmospheric oxidation of the compounds of interest is used to develop reliable and accurate chemical models that will help have precise estimations and determine the mechanisms by which volatile organic compounds interact to produce aerosol particles. Dimethyl sulfide (DMS), dimethyl disulfide (DMDS) and trimethylamine (TMA) are three relevant atmospheric compounds, due to their emissions from many natural and anthropogenic sources and recent studies on emissions of these compounds from animal waste from CAFOs has triggered the interests on the study of SOA formation from these and other similar compounds. In this study, kinetic modeling of the atmospheric oxidation mechanisms of DMDS, DMS and TMA is used to simulate atmospheric chamber studies of aerosol formation to develop accurate models and help determine the mechanisms of aerosol formation.
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SABELLI, RENATO. "Organ sulfur compounds and interactions with the detoxification and redox system enzymes." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2010. http://hdl.handle.net/2108/1194.
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Molti composti organici contenenti zolfo (OSCs) ritrovati nell'aglio sono in grado di indurre apoptosi in varie linee tumorali [80]. Recentemente, è stato ritrovato nella fase acquosa dell'aglio bollito il 2-propenil tiosolfato (2-PTS), ed è stato visto essere in grado di indurre apoptosi in più linee tumorali, tramite la produzione di ROS intracellulari [16, 75]. Inoltre, recenti
lavori [38, 39, 75] hanno messo in evidenza il fatto che la tioalchenilazione degli enzimi sia una delle cause dell'effetto citotossico di questi composti. Sulla base di ciò è stato valutato l'effetto citotossico del 2-PTS su una linea di linfoblastoma umano (HuT 78), sulla quale è stata monitorata l'attività e l'espressione di alcuni enzimi, che è stato visto essere coinvolti metabolismo degli OSCs, come la Rodanesi (TST), la Glutatione-S-transferasi (GST), la Tioredossina (Trx), la Tioredossina reduttasi (Trd). Tutti questi enzimi sono importantissimi per la vitalità cellulare, ed una loro disfunzione causa gravi patologie [7] ed è visto essere associata anche all'induzione apoptotica [2,
54, 76]. Nei nostri esperimenti è emersa la capacità del 2-PTS di ossidare tutte le proteine in esame attraverso un meccanismo di tioalchenilazione, tranne che per la Trx, di residui di cisteina essenziali per la loro attività enzimatica.
E' stata, inoltre, monitorata la reazione tra il 2-PTS ed un'altra molecola importante, il glutatione (GSH). Il 2-PTS è in grado di reagire con il GSH in condizioni fisiologiche, producendo l' S-allil-mercaptoglutatione (GSSP), il quale dopo essere stato caratterizzato è stato utilizzato per studi molecolari e cellulari. Gli studi molecolari evidenziano che il GSSP è un inibitore competitivo della GSTM1-1, ed ha una Ki di circa 0.1 mM. Gli studi cellulari sulla linea HuT 78, invece, mostrano un'inibizione della proliferazione cellulare, associata ad un blocco della fase G1/S del ciclo cellulare, e un'attivazione della MAPKinasi p38. E' stata inoltre osservata la capacità del GSSP di incrementare la concentrazione intracellulare di Doxorubicina, aumentando così l'effetto citotossico del chemioterapico, nel caso si utilizzasse un co-trattamento di GSSP e Doxo, rispetto al solo trattamento con una concentrazione non tossica di Doxo. L'aumento dell'effetto della Doxorubicina è accompagnato con un aumento dell'espressione della CDKN1A, p21.
Tutti questi risultati danno molta importanza alla scoperta del ruolo del sistema Trx-Trd-TST come sistema detossificante per gli OSCs, poichè una disregolazione dell'espressione o dell'attività di uno o più componenti del
sistema, come nel caso di alcune patologie [8, 9, 88, 91], potrebbe compromettere la capacità detossificante della cellula, giustificando così la maggiore sensibilità di alcune cellule tumorali al trattamento con gli OSCs, rispetto a quelle non tumorali, o dare luogo allo sviluppo di patologie correlate allo scorretto metabolismo degli OSCs [88, 91]. L'inibizione, inoltre, della GST da parte del 2-PTS e del GSSP da ulteriori indicazioni sul meccanismo d'azione di questo tipo di composti all'interno della cellula.
Infine, la scoperta degli effetti del GSSP da indicazioni sulla possibilità di utilizzare il co-trattamento con chemioterapici (Doxo) e OSCs come possibile approccio metodologico per abbassare le dosi di chemioterapico somministrato.Many Organ Sulfur Compounds (OSCs), founded in garlic, are able to induce apoptosis in various tumoral cell lines [80]. Recently, in the aqueous phase of boiled garlic has been found the 2-propenyl thiosulfate (2-PTS), and it can induce apoptosis in several tumor cell lines, through the intracellular ROS production [16, 75]. Besides, recent works [38, 39, 75] highlight that the enzymes thioalkenylation can be one of the causes of cytotoxic effect of this type of compounds. Since to this observations, has been valuated the cytotoxic effect of 2-PTS on a human lymphoblastoma cell line (HuT 78), monitoring the activity and expression of some enzymes involved in the OSCs metabolism, such as Rhodanese (TST), Glutathione-Stransferase (GST), Thioredoxin (Trx), Thioredoxin reductase (Trd). All these enzyme are very important for the cell vitality, and their dysfunction causes severe diseases [7] and is related to the apoptotic induction [2, 54, 76]. In our experiments we have observed the ability of 2-PTS to oxidase all the proteins examined trough a thioalkenylation mechanism of cysteine residues, except Trx, essential for their enzymatic activity. Has been also observed the reaction between the 2-PTS and another important molecule, the glutathione (GSH). The 2-PTS can react with the GSH at physiological condition, producing S-allyl-mercaptoglutathione (GSSP), which is used, after its characterization, for molecular and cellular studies. Molecular studies indicates that GSSP is a competitive inhibitor of GSTM1-1, with a Ki of about 0,1 mM. Cellular studies on HuT 78 cell line, shows an inhibition of cell proliferation, with a G1/S phase blockage of the cell cycle, and an activation of p38 MAPKinase. It has been also observed the ability of GSSP to increment the intracellular concentration of Doxorubicin, incrementing its cytotoxic effect, in the case of combinate treatment of GSSP and Dox, respect to the only treatment with a non-toxic concentration of Doxo. The increase of the effect of Doxo is attended with an increment of expression of CDKN1A, p21. All these results gives prominence to the discovery of the role of the Trx-Trd-TST system as detoxifying system of the OSCs, because a dysregulation of expression or activity of one o more components of the system, as the case of some pathology [8, 9, 88, 91], could compromise the detoxification skill of the cell, explaining the major sensibility of some tumor cells to the OSCs treatment, or causing the develop of pathology correlated to the incorrect OSCs metabolism [88, 91]. Moreover, the inhibition of GST from 2-PTS and GSSP gives further indications on the intracellular mechanism of action of this type of compounds. In the end, the discover of the GSSP effect give indications on the possibility to use the co-treatment with chemoterapic (Doxo) and OSCs as possible methodological approach to reduce the used chemoterapic dose.
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Jones, Darin E. "Sulfur and oxygen-stablized allylic cations in 4+3 cycloadditions /." free to MU campus, to others for purchase, 1996. http://wwwlib.umi.com/cr/mo/fullcit?p9821328.
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Dannecker, Karin Margaret. "EFFECT OF COAL COMPOSITION ON FUEL-NITROGEN MECHANISMS DURING FUEL RICH COMBUSTION (STAGED, POLLUTANTS)." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275302.
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Seyedain, Merriam. "A salivary chromogenic assay for periodontitis." Master's thesis, Temple University Libraries, 2011. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/142764.
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Oral BiologyM.S.
Periodontitis tends to be associated with sulfur-producing bacteria. This study uses a chromogenic sulfur detecting strip to compares whole saliva sulfur (SS) scores in subjects with and without periodontal diseases and examines the relationship between SS scores and clinical measures of periodontal status.Materials & Methods: Ninety-sex subjects were enrolled, mean age (SD) 36.5 (15.42), age range 22 to 82, percent males 52%, percent Caucasians 57%, percent cigarette smokers 33%. Periodontal evaluations including plaque index (PI), gingival index (GI), probing depth measurements (PD) and attachment levels (AL) were performed on 6 sites per tooth. Subjects were divided into 3 groups: periodontally healthy (no loss of attachment and no gingival bleeding, 17 subjects), gingivitis (no loss of attachment and presence of gingival bleeding, 54 subjects) and periodontitis (loss of attachment > 5 mm in 5 or more teeth, 25 subjects). A single chromogenic strip was used to collect a whole saliva sample from the mouth. Color reaction was scored based on a color chart. The scoring examiner was blinded to clinical status. Results: Good to moderate correlations were found between SS scores and PI (r=0.47, p=0.0001), GI (r=0.45, p=0.0001), PD (r=0.42, p=0.0001), and AL (r=0.30, p=0.002). Analysis of variance showed significant differences in SS scores among the three study groups (p = 0.0001); post-hoc analysis showed higher SS scores in periodontitis subjects than non-periodontitis subjects (p = 0.05). Nominal logistic regression adjusting for smoking showed the odds ratio of periodontitis increase by a factor of 12.76 for each increase of one unit of measure of SS. Conclusion: The results suggest that assessing whole saliva sulfur levels with a chromogenic strip has potential as a screening test for periodontal diseases.
Temple University--Theses
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Martins, Diana Maria Serafim. "Desenvolvimento de eletrodos modificados para determinação de compostos sulfurados em gasolina /." Araraquara : [s.n.], 2008. http://hdl.handle.net/11449/105745.
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Orientador: Nelson Ramos StradiottoBanca: Maria Del Pilar Taboada Sotomayor
Banca: José Fernando de Andrade
Banca: Jeosadaque José de Sene
Banca: Adaléa Lopes Brandes Marques
Resumo: Os compostos sulfurados no petróleo têm causado diversos problemas como os correlacionados à corrosão de equipamentos, envenenamento de catalisadores em processo de refino, qualidade dos produtos, além de liberação de gases tóxicos diretamente ao meio ambiente. Os compostos sulfurados em especial (enxofre elementar, difenil dissulfeto e 1-butanotiol) podem agravar estes problemas, sendo os principais causadores de corrosão de equipamentos nas refinarias de petróleo. Devido a tais considerações, a proposição deste trabalho é o desenvolvimento de metodologias eletroanalíticas para determinação de compostos sulfurados em gasolina, utilizando os eletrodos de filme de mercúrio, amálgama sólido e hexacianoferrato de cobre. No primeiro trabalho desenvolvido utilizou-se o eletrodo filme de mercúrio juntamente com as técnicas eletroanalíticas de voltametria de varredura linear (VVL), onda quadrada (VOQ) e pulso diferencial (VPD) em solução de acetato de sódio 1,4 mol L-1 e ácido acético 2% em metanol, como eletrólito suporte. O método apresentou limites de detecção na ordem de 10-9 a 10-4 mol L-1 para as técnicas eletroanalíticas de VVL, VOQ e VPD, inferiores aos já relatados na literatura usando método análogo. A quantificação dos compostos de enxofre em amostras de gasolina, a partir do monitoramento do sinal de redução sobre a superfície do eletrodo filme de mercúrio, utilizando a técnica de voltametria de onda quadrada, foi possível sem tratamento prévio da amostra, cujo procedimento mostrou ser bastante eficiente não provocando qualquer interferência associada aos constituintes da matriz, exibindo valores de 3,5x10-8, 3,7x10-7 e 4,2x10-8 mol L-1 para enxofre elementar, difenil dissulfeto e 1-butanotiol, respectivamente. A quantificação nas amostras de gasolina, avaliadas em termos... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The presence of sulfur compounds in petroleum has caused several problems including those related to the corrosion of equipments, and the quality of final products, as well as the emission of toxic gases to the environment. Sulfur compounds (elemental sulfur, diphenyl disulfide and 1-butanethiol), can increase these problems, being the main causes of corrosion of equipments in the refineries of petroleum. Based on these assumptions, the principal proposal of this work is the development of electroanalytical methodology for determination of sulfur compounds in gasoline using the electrodes of mercury film, amalgam solid and copper hexacyanoferrate. In the first developed work the mercury film electrode was used together with the electroanalytical techniques of linear scan voltammetry (LSV), square wave voltammetry (SWV) and differential pulse voltammetry (DPV) in solution of 1.4 mol L-1 sodium acetate and acetic acid 2% in methanol. The method presented detection limits in the order from 10-9 to 10-4 mol L-1 for the electroanalytical techniques of LSV, SWV and DPV. These limits are inferior to the previous related in the literature using similar method. The quantification of the sulfur compounds in gasoline samples, starting from the monitoring of the reduction sign on the mercury film electrode surface using the technique of square wave voltammetry was possible without previous sample treatment, whose procedure showed to be efficient, it not provoking any interference associated to the sample, exhibiting values of 3.5x10-8, 3.7x10-7 and 4.2x10-8 mol L-1 for elemental sulfur, diphenyl disulfide and 1-butanethiol, respectively. The quantification in the samples of gasoline in recovery terms showed that the methodology electroanalytical supplied quite acceptable results with recovery levels and precision compatible to the found by other techniques. In a second... (Complete abstract click electronic access below)
Doutor
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Dantale, S. W. "Synthesis and modification of sulfur based compounds and their application as anticancer compounds and synthetic applications of solid superacids." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 1996. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2828.
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Wilson, Craig. "Theoretical studies of reactions of reduced sulfur compounds of importance in the troposphere." Thesis, University of Warwick, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263786.
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Okbinoğlu, Tülin Nesime. "Electronic structure of sulfur-nitrogen containing compounds : correlations with theory and chemical reactivity." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/50408.
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Molecules containing sulfur-nitrogen bonds, such as sulfonamides, have long been of interest due to their many uses and chemical properties, including the potential release of nitric oxide and nitroxyl. Understanding the factors that cause sulfonamide reactivity is crucial, yet their inherent electronic complex- ity have made them difficult to examine. In this thesis, sulfur K-edge x-ray absorption spectroscopy (XAS) is used in conjunction with density functional theory (DFT) to determine the role of electronic transmission effects through the sulfur-nitrogen bond. A systematic deconstruction of the elements within the sulfonamide moiety is used as an approach to understand critical factors that dictate electronic structure.
First, the effect of oxidation state changes and variations in R-group in sulfenamides, sulfinamides and sulfonamides on intramolecular bonding are explored. Next, N-hydroxylation of the sulfonamide amide, in both alkyl sulfonamides and a series of para-substituted aryl sulfonamides with varying Hammett para-sigma constants are studied using structure-function relationships, in conjunction with DFT, to understand the role of electron donation and withdrawal to the sulfonamide moiety. The outcome of these modifications on the sulfonamide framework lead to better insight towards directed drug design and its influence on nitroxyl and nitric oxide release.Science, Faculty of
Chemistry, Department of
Graduate