O sulfeto de hidrogênio (H2S) é uma molécula produzida endogenamente que desempenha um importante papel em diversos processos fisiológicos e patológicos, incluindo inflamação e nocicepção. Assim, os objetivos deste estudo foram avaliar os efeitos de um doador de H2S de liberação lenta, o composto GYY-4137, na sinovite aguda induzida por carragenina (CGN) na articulação temporomandibular (ATM) de ratos, e caracterizar os mecanismos envolvidos. Os resultados mostraram que na sinovite aguda de ATM (caracterizada por alodinia mecânica e infiltração de leucócitos 4 h após a injeção i.art. de CGN), a administração concomitante do composto GYY-4137 resultou em redução destes parâmetros envolvendo a participação de GMPc e abertura de canais KATP, sem afetar a produção aumentada das citocinas IL-1β e IL-6. Estes achados dão suporte ao uso de doadores de H2S como potenciais alternativas terapêuticas para o tratamento de distúrbios temporomandibulares. / Hydrogen sulfide (H2S) is an endogenously produced molecule that plays an important role in many physiological and pathological processes, including inflammation and nociception. The objectives of this study were to evaluate the effects of slow-release H2S donor, compound GYY-4137, in the carrageenan (CGN) induced acute synovitis of the temporomandibular joint (TMJ) in rats, and to characterize the mechanisms involved. The results showed that in the acute TMJ synovitis (characterized by mechanical allodynia and leukocyte infiltration 4 h after the i.art CGN injection), the concomitant administration of compound GYY-4137 resulted in reduction of these parameters, involving the participation of cGMP and KATP opening, without affecting the increased production of the cytokines IL-1β and IL-6. These findings support the use of H2S donors as potential therapeutic alternatives for treatment of temporomandibular disorders.

Nesse trabalho foi estudada uma técnica para a detecção de OHTC na água salina. Descobriu-se que certos complexos de rutênio em determinados valores de pH reagem com a molécula de OHTC e isto é detectável por espectrofotometria UV-Vis. Foram estudados os complexos fac-[RuCl2(S-DMSO)3(O-DMSO)] (complexo 1), {[(DMSO)2H][trans-RuCl4(DMSO)2]} (complexo 2) e cis-[RuCl2(bpy)2].2H2O (complexo 3). O complexo 1 possui um dos ligante (O-DMSO) que pode ser substituído pelo OHTC. Já o complexo 2 possui um dos ligantes (S-DMSO) na posição trans um ao outro, e o complexo 3 possui os 2 íons Cl- para tal finalidade. Determinou-se que o complexo 1 é viável, mesmo em presença de sais presentes na água do mar. Assim a reação foi realizada em função do tempo, variação do pH, temperatura e concentração de OHTC. Nos outros dois complexos os estudos foram realizados sem a variação da temperatura e concentração de OHTC. / p>In this work we studied a technique for detection of OHTC in water. It was discovered that complexes involving ruthenium, on determined pH values, react with the OHTC molecule and this is detectable by UV-VIS spectroscopy. The complexes fac-[RuCl2(S-dmso)3(O-dmso)] (complex 1), {[(DMSO)2H][trans-Ru(DMSO)2Cl4]} (complex 2), and cis-[RuCl2(bpy)2].2H2O (complex 3) were studied. The complex 1 present one position ( O - DMSO) which can be substituted by the OHTC. Additionally, the complex 2 present two ligands ( S- DMSO) trans between each other, and the complex 3 present two chloride ions for the same porpose of complex 1 respectively. It was determined that the complex 1 was able to react with OHTC even in presence of the salts present in sea water. Thereby, the reaction involving complex 1 and OHTC was monitored in function of the time, pH, temperature, and finally concentration of OHTC. On the other two complexes, the reaction was studied without variation of temperature and concentration of OHTC.

Nesse trabalho foi estudada uma técnica para a detecção de OHTC na água salina. Descobriu-se que certos complexos de rutênio em determinados valores de pH reagem com a molécula de OHTC e isto é detectável por espectrofotometria UV-Vis. Foram estudados os complexos fac-[RuCl2(S-DMSO)3(O-DMSO)] (complexo 1), {[(DMSO)2H][trans-RuCl4(DMSO)2]} (complexo 2) e cis-[RuCl2(bpy)2].2H2O (complexo 3). O complexo 1 possui um dos ligante (O-DMSO) que pode ser substituído pelo OHTC. Já o complexo 2 possui um dos ligantes (S-DMSO) na posição trans um ao outro, e o complexo 3 possui os 2 íons Cl- para tal finalidade. Determinou-se que o complexo 1 é viável, mesmo em presença de sais presentes na água do mar. Assim a reação foi realizada em função do tempo, variação do pH, temperatura e concentração de OHTC. Nos outros dois complexos os estudos foram realizados sem a variação da temperatura e concentração de OHTC. / p>In this work we studied a technique for detection of OHTC in water. It was discovered that complexes involving ruthenium, on determined pH values, react with the OHTC molecule and this is detectable by UV-VIS spectroscopy. The complexes fac-[RuCl2(S-dmso)3(O-dmso)] (complex 1), {[(DMSO)2H][trans-Ru(DMSO)2Cl4]} (complex 2), and cis-[RuCl2(bpy)2].2H2O (complex 3) were studied. The complex 1 present one position ( O - DMSO) which can be substituted by the OHTC. Additionally, the complex 2 present two ligands ( S- DMSO) trans between each other, and the complex 3 present two chloride ions for the same porpose of complex 1 respectively. It was determined that the complex 1 was able to react with OHTC even in presence of the salts present in sea water. Thereby, the reaction involving complex 1 and OHTC was monitored in function of the time, pH, temperature, and finally concentration of OHTC. On the other two complexes, the reaction was studied without variation of temperature and concentration of OHTC.

<p>Methylglyoxal (MG) is a reactive glucose metabolite and a known causative factor for hypertension and diabetes. Hydrogen sulfide (H₂S), on the other hand, is a gasotransmitter with multifaceted physiological functions, including anti-oxidant and vasodilatory properties. The present study demonstrates that MG and H₂S can interact with and modulate each other's functions. Upon <i>in vitro</i> incubations, we found that MG and H₂S can directly interact to form three possible MG-H₂S adducts. Furthermore, the endogenous production level of MG or H₂S was significantly reduced in a concentration-dependent manner in rat vascular smooth muscle cells (A-10 cells) treated with NaHS, a H₂S donor, or MG, respectively. Indeed, MG-treated A-10 cells exhibited a concentration-dependent down-regulation of the protein and activity level of cystathionine &gamma;-lyase (CSE), the main H₂S-generating enzyme in the vasculature. Moreover, H₂S can induce the inhibition of MG-generated ROS production in a concentration-dependent manner in A-10 cells. In 6-22 week-old CSE knockout male mice (CSE^-/-), mice with lower levels of vascular H₂S, we observed a significant elevation in MG levels in both plasma and renal extracts. Renal triosephosphates were also significantly increased in the 6-22 week-old CSE^-/- mice. To identify the source of the elevated renal MG levels, we found that the activity of fructose-1,6-bisphosphatase (FBPase), the rate-limiting enzyme in gluconeogenesis, was significantly down-regulated, along with lower levels of its product (fructose-6-phosphate) and higher levels of its substrate (fructose-1,6-bisphosphate) in the kidney of 6-22 week-old CSE^-/- mice. We have also observed lower levels of the gluconeogenic regulator, peroxisome proliferator-activated receptor-&gamma; coactivator (PGC)-1&alpha;, and its down-stream targets, FBPase-1 and -2, phosphoenolpyruvate carboxykinase (PEPCK), and estrogen-related receptor (ERR)&alpha; mRNA expression levels in renal extracts from 6-22 week-old CSE^-/- mice. Likewise, FBPase-1 and -2 mRNA levels were also significantly down-regulated in aorta tissues from 14-16 week-old CSE^-/- mice. Administration of 30 and 50 &#x00B5;M NaHS induced a significant increase in FBPase-1 and PGC-1&alpha; in rat A-10 cells. We have also observed a significant up-regulation of PEPCK and ERR&alpha; mRNA expression levels in 50 &#x00B5;M NaHS-treated A-10 cells, further confirming the involvement of H₂S in regulating the rate of gluconeogenesis and MG formation. Overall, this unique study demonstrates the existence of a negative correlation between MG and H₂S in the vasculature. Further elucidation of this cross-talk phenomenon between MG and H₂S could lead to more elaborate and effective therapeutic regimens to combat metabolic syndrome and its related health complications.</p>

In nature, organic matter is degraded by microorganisms. During the degradation gases formedincludes methane, carbon dioxide, hydrogen sulfide, and small amounts of other gases such asVOCs. This has been utilized with help of anaerobic digesters, where environments have beencreated, in which these organisms thrive. In these chambers the gases are collected together intosomething called biogas.Biogas is a renewable energy source where the methane gas natural affinity for combustion inoxygen-containing environments is being used. By separating the methane from the other gases, theenergy value becomes closer to that of natural gas. The upgraded biogas can thus act as a substitutefor natural gas and be used as a fuel for vehicles, a need that has increased during the last years.This is preferred since natural gas is a fossil fuel.A technique used for upgrading biogas is water scrubbers. By using the gases different tendency todissolve into the water, carbon dioxide and hydrogen sulfide can be removed. During this process asmall amount methane and VOC becomes absorbed as well. The upgraded biogas obtains a methanecontent of approximately 98 % and can then be used as a fuel for vehicles. The removed gases are atthe same time released from the water to the effluent air leaving the upgrading plant. This has beendeemed inappropriate since the hydrogen sulfide is a corrosive and highly toxic gas. The methaneand VOCs that leaves with the effluent air provides negative effects to the greenhouse effect andglobal environment.This study has examined the issue of how to treat the gases that are emitted by the effluent air.Using measurements to find the percentage amounts of the different gases in the effluent air and inthe raw biogas, annual quantities of emissions could be calculated. From these, various treatmentmethods have been analyzed where the author finally concluded that a reduction of hydrogensulfide should be achieved with help of iron in a filter. Methane has instead been proposed to betreated with a compost filter. / I naturen bryts organiska ämnen ned med hjälp av mikroorganismer. Under nedbrytningen bildasbland annat metan, koldioxid, svavelväte samt flera andra gaser så som VOC. Detta har utnyttjats dåman med hjälp av anaeroba rötkammare skapat miljöer där dessa mikroorganismer trivs. I dessakammare samlas gaserna ihop till någonting som kallas för biogas.Biogas är en förnyelsebar energikälla där man utnyttjar metangasens naturliga förutsättningar till attförbrännas i syrehaltiga miljöer. Genom att separera metangasen från de övriga gaserna, kanenergivärden nära naturgas fås. Den uppgraderade gasen kan på så vis agera som ett substitut tillnaturgas och därmed användas som drivmedel till fordon, ett behov som ökat under de senaste åren.Detta är att föredra då naturgas är ett fossilt bränsle.En teknik som används för separeringen av gaserna är vattenskrubbrar. Genom att utnyttja gasernasolika benägenhet att lösa sig i vatten så kan koldioxiden och svavelvätet tas bort. Under dennaprocess absorberas även mindre mängder metan och VOC. Den uppgraderade biogasen får genomprocessen cirka 98 % metanhalt och kan därefter användas för att driva fordon. De borttagnagaserna frigörs samtidigt från vattnet och släpps istället ut från uppgraderingsanläggningen medhjälp av en luftström. Detta har bedömts vara olämpligt då svavelvätet är korrosivt och en mycketgiftig gas. Metanen och VOCn som följer med den utgående luften har negativa egenskaper förväxthuseffekten och den globala miljön.Denna studie har undersökt hur de gaser som normalt släpps ut med det utgående luftflödet skallbehandla. Med hjälp av mätningar av de procentuella gasmängderna i den utgående luften samt iden råa biogasen har kvantiteter på årliga emissionerna kunnat uppskattas. Utifrån dessa har olikareningsmetoder analyserats där slutsatsen är att reducera svavelvätet med hjälp av Järn i ett filter.Metangasen har istället föreslagits bli renad i ett kompost filter.

<p>Methylglyoxal (MG) is a reactive glucose metabolite and a known causative factor for hypertension and diabetes. Hydrogen sulfide (H₂S), on the other hand, is a gasotransmitter with multifaceted physiological functions, including anti-oxidant and vasodilatory properties. The present study demonstrates that MG and H₂S can interact with and modulate each other's functions. Upon <i>in vitro</i> incubations, we found that MG and H₂S can directly interact to form three possible MG-H₂S adducts. Furthermore, the endogenous production level of MG or H₂S was significantly reduced in a concentration-dependent manner in rat vascular smooth muscle cells (A-10 cells) treated with NaHS, a H₂S donor, or MG, respectively. Indeed, MG-treated A-10 cells exhibited a concentration-dependent down-regulation of the protein and activity level of cystathionine &gamma;-lyase (CSE), the main H₂S-generating enzyme in the vasculature. Moreover, H₂S can induce the inhibition of MG-generated ROS production in a concentration-dependent manner in A-10 cells. In 6-22 week-old CSE knockout male mice (CSE^-/-), mice with lower levels of vascular H₂S, we observed a significant elevation in MG levels in both plasma and renal extracts. Renal triosephosphates were also significantly increased in the 6-22 week-old CSE^-/- mice. To identify the source of the elevated renal MG levels, we found that the activity of fructose-1,6-bisphosphatase (FBPase), the rate-limiting enzyme in gluconeogenesis, was significantly down-regulated, along with lower levels of its product (fructose-6-phosphate) and higher levels of its substrate (fructose-1,6-bisphosphate) in the kidney of 6-22 week-old CSE^-/- mice. We have also observed lower levels of the gluconeogenic regulator, peroxisome proliferator-activated receptor-&gamma; coactivator (PGC)-1&alpha;, and its down-stream targets, FBPase-1 and -2, phosphoenolpyruvate carboxykinase (PEPCK), and estrogen-related receptor (ERR)&alpha; mRNA expression levels in renal extracts from 6-22 week-old CSE^-/- mice. Likewise, FBPase-1 and -2 mRNA levels were also significantly down-regulated in aorta tissues from 14-16 week-old CSE^-/- mice. Administration of 30 and 50 &#x00B5;M NaHS induced a significant increase in FBPase-1 and PGC-1&alpha; in rat A-10 cells. We have also observed a significant up-regulation of PEPCK and ERR&alpha; mRNA expression levels in 50 &#x00B5;M NaHS-treated A-10 cells, further confirming the involvement of H₂S in regulating the rate of gluconeogenesis and MG formation. Overall, this unique study demonstrates the existence of a negative correlation between MG and H₂S in the vasculature. Further elucidation of this cross-talk phenomenon between MG and H₂S could lead to more elaborate and effective therapeutic regimens to combat metabolic syndrome and its related health complications.</p>

The objective of this study is to determine hydrate formation conditions of methane- hydrogen sulfide mixtures. During the study, an experimental work is carried out by using a system that contains a high-pressure hydrate formation cell and pressure-temperature data is recorded in each experiment. Different H2S concentrations and both brine and distilled water are used in the experiments and the Black Sea conditions, which are suitable for methane-hydrogen sulfide hydrate formation are examined. Considering the pressure-temperature data obtained, hydrate equilibrium conditions are determined as well as the number of moles of free gas in the hydrate formation cell. The change in the number of moles of free gas in the hydrate formation cell with respect to time is considered as a way of determining rate of hydrate formation. Effects of H2S concentration and salinity on hydrate formation conditions of methane-hydrogen sulfide mixtures are also studied. It is observed that an increase in the salinity shifts the methane-hydrogen sulfide hydrate equilibrium condition to lower equilibrium temperatures at a given pressure. On the other hand, with an increase in H2S concentration the methane hydrogen sulfide hydrate formation conditions reach higher equilibrium temperature values at a given pressure. After the study, it can be also concluded that the Black Sea has suitable conditions for hydrate formation of methane hydrogen sulfide mixtures, considering the results of the experiments.

The goal is of this project was to identify principles to guide the development of high performance dense film membranes for natural gas sweetening using hydrogen sulfide and carbon dioxide gas mixtures as models under aggressive sour gas feed conditions. To achieve this goal, three objectives were developed to guide this research. The first objective was to study the performance of cellulose acetate (CA) and an advanced crosslinkable polyimide (PDMC) dense film membrane for H₂S separation from natural gas. The second objective was to engineer those polymers to produce membrane materials with superior performance as measured by efficiency, productivity, and plasticization resistance, and the third objective was to determine the separation performance of these engineered membrane materials under more aggressive, realistic natural gas feeds, and to perform a detailed transport analysis of the factors that impact their performance. Work on the first objective showed that in neat CA, penetrant transport is controlled by both the solubility and mobility selectivity, with the former being more dominant, leading to a high overall CO₂/CH₄ (33) and H₂S/CH₄ (35) ideal selectivities. However, in uncrosslinked PDMC, H₂S/CH₄ selectivity favored sorption only, whereas CO₂/CH₄ selectivity favored both mobility and sorption selectivity, leading to a high CO₂/CH₄ (37) but low H₂S/CH₄ (12) ideal selectivities. However, the latter polymer showed more plasticization resistance for CO₂. In the second objective, both materials were engineered. A new technique referred to as “GCV-Modification” was introduced in which cellulose acetate was grafted using vinyltrimethoxysilane (VTMS), then hydrolyzed and condensed to form a polymer network. PDMC was also covalently crosslinked to enhance its performance. GCV-Modified CA showed significant performance improvements for H₂S and CO₂ removal; the permeability of CO₂ and H₂S were found to be 139 and 165 Barrer, respectively, which represented a 30X and 34X increase compared to the pristine CA polymer. The H₂S/CH₄ and CO₂/CH₄ ideal selectivities were found to be 39 and 33, respectively. Crosslinked PDMC showed a higher CO₂/CH₄ selectivity of 38 with a better plasticization resistance for CO₂ and H₂S. In the third objective, these materials were tested under aggressive ternary mixtures of H₂S/CO₂/CH₄ with both vacuum and nonvacuum downstream. Even under aggressive feed conditions, GCV-Modified CA showed better performance vs. PDMC, and it remained were fairly stable, making it a potential candidate for aggressive sour gas separations, not only because of its significantly higher productivity, which will help decrease the surface area needed for separation, thereby reducing operating costs, but also because of the lower cost of the raw material GCV-Modified CA compared to PDMC.

Thesis (MSc (Meteorology))-University of Pretoria, 2006. / Includes bibliographical references. Available on the Internet via the World Wide Web.

Hydrogen sulfide (H2S) is a toxic gas that causes respiratory failure and death at high concentrations, but at low concentrations, it functions as a signaling molecule in vasodilation and neuromodulation, and it protects cells and tissues from reperfusion injury, hypoxia, hyperglycemia and endothelial dysfunction. Several model organisms have been used to study the physiological roles and signaling pathways of H2S. The roundworm Caenorhabditis elegans is a remarkable model for studying the physiology, developmental biology and signaling of H2S; however, the metabolism of H2S in this animal is largely unknown. Cystathionine beta-synthase (CBS) is one of three H2S-producing enzymes in mammals. Notably, C. elegans possesses 6 genes that encode proteins homologous to CBS, namely cbs- 1, cbs-2, cysl-1, cysl-2, cysl-3 and cysl-4. In this thesis we studied the roles of these genes in H2S metabolism and signaling. First, we identified cbs-1 as the gene encoding CBS in C. elegans; the recombinant purified CBS-1 protein exhibited canonical CBS activity, and RNA interference-mediated silencing of cbs-1 resulted in decreased CBS activity and increased homocysteine levels in worm extracts, recapitulating the phenotypes of CBS deficiency in mammals. Notably, the nematode and human enzymes differ in their domain...