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Zeitschriftenartikel zum Thema "OX2"
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Silveyra, Patricia, Paolo N. Catalano, Victoria Lux-Lantos und Carlos Libertun. „Impact of proestrous milieu on expression of orexin receptors and prepro-orexin in rat hypothalamus and hypophysis: actions of Cetrorelix and Nembutal“. American Journal of Physiology-Endocrinology and Metabolism 292, Nr. 3 (März 2007): E820—E828. http://dx.doi.org/10.1152/ajpendo.00467.2006.
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Orexins and their receptors OX1 and OX2 regulate energy balance and the sleep-wake cycle. We studied the expression of prepro-orexin (PPO), OX1, and OX2 in brain and pituitary under the influence of the hormonal status in adult rats. Primarily, PPO, OX1, and OX2 expression was determined in Sprague-Dawley female cycling rats during proestrus and in males. Animals were killed at 2-h intervals. Anterior (AH) and mediobasal (MBH) hypothalamus, anterior pituitary (P), and frontoparietal cortex (CC) were homogenized in TRIzol, and mRNAs were obtained for screening of PPO, OX1, OX2 expression by semiquantitative RT-PCR. Main findings were confirmed and extended to all days of the cycle by quantitative real-time RT-PCR. Hormones and food consumption were determined. Finally, OX1, OX2, and PPO were measured by real-time RT-PCR in tissues collected at 1900 of proestrus after treatments at 1400 with ovulation-blocking agents Cetrorelix or pentobarbital. OX1 and OX2 expression increased at least threefold in AH, MBH, and P, but not in CC, between 1700 and 2300 of proestrus, without variations in estrus, diestrus, or in males. PPO in AH and MBH showed a fourfold or higher increase only during proestrus afternoon. Cetrorelix or pentobarbital prevented increases of OX1 and OX2 only in the pituitary and blunted gonadotropin surges, but left OX1, OX2, and PPO brain expression unchanged. Reproduction, energy balance, and sleep-wake cycle are integrated. Here, we demonstrate that, in the physiological neuroendocrine condition leading to ovulation, information to the orexinergic system acts in hypothalamus and pituitary by different mechanisms.
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Silveyra, Patricia, Victoria Lux-Lantos und Carlos Libertun. „Both orexin receptors are expressed in rat ovaries and fluctuate with the estrous cycle: effects of orexin receptor antagonists on gonadotropins and ovulation“. American Journal of Physiology-Endocrinology and Metabolism 293, Nr. 4 (Oktober 2007): E977—E985. http://dx.doi.org/10.1152/ajpendo.00179.2007.
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Orexins are peptides controlling feeding, sleep, and neuroendocrine functions. They are synthesized by the hypothalamus with projections throughout the brain. Orexins and their orexin 1 (OX1) and orexin 2 receptors (OX2) are present outside the central nervous system. Here the expression of preproorexin (PPO), OX1, and OX2 was studied in rat ovaries. PPO, OX1, and OX2 were determined by quantitative real-time RT-PCR in ovaries of cycling Sprague-Dawley rats on all days of the cycle. Serum hormones and food consumption were determined. Ovarian OX1 and OX2 expression was then studied after ovulation blockade with Cetrorelix or Nembutal. Finally, proestrous rats were treated at 1400 and 1900 with a selective OX1 antagonist (SB-334867-A) and/or a selective OX2 antagonist (JNJ-10397049), and hormone levels, ovulation, and ovarian histology were studied. Both receptors' expression increased in the ovary between 1700 and 2300 of proestrus exclusively, in coincidence with hormone peaks, but not with the dark-light cycle or food intake. PPO was not detected. Cetrorelix or Nembutal prevented the increases of OX1 and OX2 while blunting gonadotropin peaks. SB-334867-A and JNJ-10397049, alone or combined, decreased serum gonadotropins and reduced ova number the following morning; ovaries showed a bloody (hyperemic and/or hemorrhagic) reaction with more preovulatory follicles and less corpora lutea. Here we demonstrate for the first time an increased ovarian expression of both OX1 and OX2, only during proestrous afternoon, and its hormone dependence but not dependence on the dark-light cycle. Two new receptor antagonists reduced proestrous gonadotropins and/or ova number while producing ovarian structural changes.
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Jöhren, Olaf, Norbert Brüggemann, Andreas Dendorfer und Peter Dominiak. „Gonadal Steroids Differentially Regulate the Messenger Ribonucleic Acid Expression of Pituitary Orexin Type 1 Receptors and Adrenal Orexin Type 2 Receptors“. Endocrinology 144, Nr. 4 (01.04.2003): 1219–25. http://dx.doi.org/10.1210/en.2002-0030.
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Abstract Hypothalamic prepro-orexin as well as pituitary and adrenal orexin receptors are gender-specifically expressed. To assess the regulation by gonadal steroids, we investigated the effect of 17β-estradiol in female and of testosterone in male rats on prepro-orexin and orexin receptor mRNA expression. Rats were either sham-operated or gonadectomized and subsequently treated with placebo, 17β-estradiol, or testosterone for 21 d. Tissue mRNA levels of prepro-orexin, orexin type-1 (OX1), and orexin type-2 (OX2) receptors were measured using quantitative real-time RT-PCR. In female rats, pituitary OX1 receptor mRNA levels were increased 12-fold after ovariectomy compared with sham- operated rats. The increase of pituitary OX1 receptor mRNA was inhibited by treatment with 17β-estradiol. Adrenal mRNA levels of OX2 receptors in ovariectomized rats were increased 2-fold compared with sham-operated rats and were also reduced by treatment with 17β-estradiol. In male rats, orchidectomy increased the mRNA levels of pituitary OX1 receptors compared with sham-operated rats. In contrast, adrenal OX2 receptor mRNA was reduced after orchidectomy. Testosterone treatment reversed the effect of orchidectomy on pituitary OX1 and adrenal OX2 receptors. In the hypothalamus, no differences were found in the mRNA levels of prepro-orexin, OX1, and OX2 receptors between sham-operated, placebo-treated, and steroid-treated female or male rats. Our results indicate that gonadal steroids differentially regulate pituitary OX1 receptors and adrenal OX2 receptors in male and female rats and may contribute to specific sex- dependent neuroendocrine and endocrine actions of orexins.
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Brown, Robyn Mary, Shaun Yon-Seng Khoo und Andrew John Lawrence. „Central orexin (hypocretin) 2 receptor antagonism reduces ethanol self-administration, but not cue-conditioned ethanol-seeking, in ethanol-preferring rats“. International Journal of Neuropsychopharmacology 16, Nr. 9 (01.10.2013): 2067–79. http://dx.doi.org/10.1017/s1461145713000333.
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Abstract Orexins are hypothalamic neuropeptides which bind to two G-protein-coupled receptors, orexin-1 (OX1R) and orexin-2 (OX2R) receptor. While a role for OX1R has been established in both ethanol reinforcement and ethanol-seeking behaviour, the role of OX2R in these behaviours is relatively less-studied. The aim of this study was to determine the role of central OX2R in ethanol-taking and ethanol-seeking behaviour. Indiana ethanol-preferring rats were trained to self-administer ethanol (10% w/v) or sucrose (0.7–1% w/v) in the presence of reward-associated cues before being implanted with indwelling guide cannulae. The selective OX2R antagonist TCS-OX2-29 was administered i.c.v. to assess its effect on operant self-administration and cue-induced reinstatement following extinction. Following i.c.v. injection TCS-OX2-29 reduced self-administration of ethanol, but not sucrose. Despite reducing ethanol self-administration, TCS-OX2-29 had no impact on cue-induced reinstatement of ethanol seeking. To determine where in the brain OX2R were acting to modulate ethanol self-administration, TCS-OX2-29 was microinjected into either the shell or core of the nucleus accumbens (NAc). Intra-NAc core, but not shell, infusions of TCS-OX2-29 decreased responding for ethanol. Importantly, the doses of TCS-OX2-029 used were non-sedating. Collectively, these findings implicate OX2R in the NAc in mediating the reinforcing effects of ethanol. This effect appears to be drug-specific as antagonism of central OX2R had no impact on sucrose self-administration. Thus, OX2R in addition to OX1R may represent a potential therapeutic target for the treatment of ethanol-use disorders. However, unlike OX1R, no impact of OX2R antagonism was observed on cue-induced reinstatement, suggesting a more prominent role for OX2R in ethanol self-administration compared to cue-conditioned ethanol-seeking.
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Jöhren, Olaf, Steffi J. Neidert, Marco Kummer, Andreas Dendorfer und Peter Dominiak. „Prepro-Orexin and Orexin Receptor mRNAs Are Differentially Expressed in Peripheral Tissues of Male and Female Rats“. Endocrinology 142, Nr. 8 (01.08.2001): 3324–31. http://dx.doi.org/10.1210/endo.142.8.8299.
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Abstract Orexins are produced specifically by neurons located in the lateral hypothalamus. Recent results suggested peripheral actions of orexins. Therefore, we analyzed the mRNA expression of prepro-orexin and the orexin receptor subtypes OX1 and OX2 in peripheral rat tissues. Using real-time quantitative RT-PCR we detected significant amounts of prepro-orexin mRNA in testis, but not in ovaries. OX1 receptor mRNA was highly expressed in the brain and at lower levels in the pituitary gland. Only small amounts of OX1 receptor mRNA were found in other tissues such as kidney, adrenal, thyroid, testis, ovaries, and jejunum. Very high levels of OX2 receptor mRNA, 4-fold higher than in brain, were found in adrenal glands of male rats. Low amounts of OX2 receptor mRNA were present in lung and pituitary. In adrenal glands, OX2 receptor mRNA was localized in the zona glomerulosa and reticularis by in situ hybridization, indicating a role in adrenal steroid synthesis and/or release. OX1 receptor mRNA in the pituitary and OX2 receptor mRNA in the adrenal gland were much higher in male than in female rats. In the hypothalamus, OX1 receptor mRNA was slightly elevated in female rats. The differential mRNA expression of orexin receptor subtypes in peripheral organs indicates discrete peripheral effects of orexins and the existence of a peripheral orexin system. This is supported by the detection of orexin A in rat plasma. Moreover, the sexually dimorphic expression of OX1 and OX2 receptors in the hypothalamus, pituitary, and adrenal glands suggests gender-specific roles of orexins in the control of endocrine functions.
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Mazzocchi, G., L. K. Malendowicz, F. Aragona, P. Rebuffat, L. Gottardo und G. G. Nussdorfer. „Human Pheochromocytomas Express Orexin Receptor Type 2 Gene and Display an in Vitro Secretory Response to Orexins A and B“. Journal of Clinical Endocrinology & Metabolism 86, Nr. 10 (01.10.2001): 4818–21. http://dx.doi.org/10.1210/jcem.86.10.7929.
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Orexins A and B are hypothalamic peptides, that act through two receptor subtypes, called OX1-R and OX2-R. OX1-R selectively binds orexin A, whereas OX2-R is nonselective for both orexins. High levels of OX1-R mRNA and low levels of OX2-R mRNA have been previously detected in the human adrenal cortex and medulla. Here we demonstrated by RT-PCR the expression of the OX2-R, but not the OX1-R, gene in 10 benign secreting pheochromocytomas. Both orexins A and B stimulated catecholamine secretion from pheochromocytoma slices; the maximal effective concentration was 10−8 mol/liter. Orexins A and B (10−8 mol/liter) increased IP3, but not cAMP production, by tumor slices, and the effect was blocked by the PLC inhibitor U-73122. The catecholamine response to 10−8 mol/liter orexins A and B was abolished by either U-73122 or the PKC antagonist calphostin C and was unaffected by the adenylate cyclase inhibitor SQ-22536 and the PKA inhibitor H-89. Collectively, these findings suggest that orexins stimulate catecholamine secretion from human pheochromocytomas, acting through OX2-R coupled to the PLC-PKC signaling pathway.
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Spinazzi, R., M. Rucinski, G. Neri, L. K. Malendowicz und G. G. Nussdorfer. „Preproorexin and Orexin Receptors Are Expressed in Cortisol-Secreting Adrenocortical Adenomas, and Orexins Stimulate in Vitro Cortisol Secretion and Growth of Tumor Cells“. Journal of Clinical Endocrinology & Metabolism 90, Nr. 6 (01.06.2005): 3544–49. http://dx.doi.org/10.1210/jc.2004-2385.
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Orexins A and B are hypothalamic peptides that originate from the proteolytic cleavage of preproorexin and act through two subtypes of receptors, named OX1-R and OX2-R. OX1-R almost exclusively binds orexin-A, whereas OX2-R is nonselective for both orexins. We previously found that orexin-A, via the OX1-R, stimulates cortisol secretion from dispersed human adrenocortical cells. In this study, we demonstrate that six of eight cortisol-secreting adenomas expressed preproorexin mRNA, and seven of 10 adenomas contained measurable amounts of orexin-A but not orexin-B. Normal adrenal cortexes neither expressed preproorexin nor contained orexins. All adenomas expressed OX1-R and OX2-R mRNAs, and real-time PCR showed that the expression of both receptors was up-regulated in adenomas, compared with normal adrenal cortex. Orexin-A concentration-dependently raised basal cortisol secretion from freshly dispersed normal and adenomatous cells, minimal and maximal effective concentrations being 10−10 and 10−8m, and the peptide efficacy (percent increase elicited by 10−8m orexin-A) was significantly higher in adenomas than in the normal adrenal cortex. Orexin-B was ineffective, thereby indicating that orexin secretagogue action is mediated by the OX1-R. In contrast, both orexins (10−8m) raised the proliferative activity of cultured normal and adenomatous cells, suggesting that this effect is mediated by OX2-R or both receptor subtypes. Collectively, our findings allow us to conclude that the orexin system is overexpressed in cortisol-secreting adenomas and suggest that orexin-A may act as an autocrine-paracrine regulator of the secretory activity and growth of some of these adrenal tumors.
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Mazzocchi, G., L. K. Malendowicz, L. Gottardo, F. Aragona und G. G. Nussdorfer. „Orexin A Stimulates Cortisol Secretion from Human Adrenocortical Cells through Activation of the Adenylate Cyclase-Dependent Signaling Cascade“. Journal of Clinical Endocrinology & Metabolism 86, Nr. 2 (01.02.2001): 778–82. http://dx.doi.org/10.1210/jcem.86.2.7233.
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Orexins A and B are two hypothalamic peptides that increase food intake and body weight and probably play a role in the sleep regulation. They act through two subtypes of G protein-coupled receptors, called OX1-R and OX2-R. OX1-R selectively binds orexin-A, whereas OX2-R is nonselective for both orexins. Orexins did not affect the in vitro secretion of either catecholamine or aldosterone from human adrenals. Conversely, orexin A, but not orexin B, concentration dependently increased basal cortisol secretion from dispersed adrenocortical cells; the maximal effective concentration was 10−8 mol/L. Orexin A (10−8 mol/L) enhanced the cortisol response to maximal effective concentrations (10−9 mol/L) of angiotensin II and endothelin-1, but only to low concentrations of ACTH (10−12/10−11 mol/L). Orexin A (10−8 mol/L) increased basal cAMP release by dispersed adrenocortical cells, and the effect was blocked by the adenylate cyclase inhibitor SQ-22536. The cortisol response to 10−8 mol/L orexin A was unaffected by the ACTH receptor antagonist corticotropin-inhibiting peptide, but was abolished by either SQ-22536 or the protein kinase A inhibitor H-89. RT-PCR demonstrated high levels of OX1-R messenger ribonucleic acid and very low levels of OX2-R messenger ribonucleic acid in human adrenal zona fasciculata-reticularis and adrenal medulla. Collectively, our findings suggest that orexins selectively stimulate glucocorticoid secretion from human adrenocortical cells, acting through OX1-R coupled with the adenylate cyclase-dependent signaling pathway.
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Turku, Ainoleena, Alexandre Borrel, Teppo O. Leino, Lasse Karhu, Jyrki P. Kukkonen und Henri Xhaard. „Pharmacophore Model To Discover OX1 and OX2 Orexin Receptor Ligands“. Journal of Medicinal Chemistry 59, Nr. 18 (08.09.2016): 8263–75. http://dx.doi.org/10.1021/acs.jmedchem.6b00333.
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Malherbe, Pari, Edilio Borroni, Emmanuel Pinard, Joseph G. Wettstein und Frédéric Knoflach. „Biochemical and Electrophysiological Characterization of Almorexant, a Dual Orexin 1 Receptor (OX1)/Orexin 2 Receptor (OX2) Antagonist: Comparison with Selective OX1 and OX2 Antagonists“. Molecular Pharmacology 76, Nr. 3 (19.06.2009): 618–31. http://dx.doi.org/10.1124/mol.109.055152.
Der volle Inhalt der QuelleDissertationen zum Thema "OX2"
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Augustsson, Adam. „Reindeer Husbandry and Wind Power : Discourses surrounding the construction of IKEA's wind park on Glötesvålen and its local effects on reindeer husbandry“. Thesis, Malmö universitet, Malmö högskola, Institutionen för Urbana Studier (US), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-42460.
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The exploitation of land in Northern Sweden has caused a significant depletion of grazing grounds for semi-domesticated reindeer. This is a threat to the indigenous Sami reindeer herders of Sweden, who rely on the grazing ground in order to sustainably feed their herds. In the last decade, a significant amount of grazing land has been lost due to the construction of wind power parks (WPP) in important grazing regions. This thesis examines the discourse surrounding a WPP built in Härjedalen for IKEA. The WPP was built on Glötesvålen, a unique highland used for grazing by Mittådalen, a local herding community. Through a dissection of electronic sources and semi-structured interviews, the author conducts a discourse analysis to identify the most prevalent narratives surrounding the construction of IKEA’s WPP on Glötesvålen. An inductive approach is used to identify underlying ideologies present in the discourse through a relevant theoretical framework. The results show a pervasive enthusiasm for the WPP as a pivot towards renewable energy which mirrors the ideology of ecological modernization. The results also find a critical narrative which lifts the uneven power dynamic experienced by reindeer herders. This narrative is understood through the lens of Spivak’s (2010) “Can the Subaltern Speak?”. An additional discourse found is the symbolic issue between industrial ecological transitioning and the right to reindeer husbandry as a cultural heritage.Exploateringen av mark i norra Sverige har orsakat en betydande förlust av betesmarker för renskötare. Detta hotar den svensk-samiska rennäringen, som förlitar sig på betesmarken för att hållbart mata sina hjordar. Under det senaste decenniet har en betydande mängd betesmark gått förlorad på grund av den ökande mängden vindkraftsparker (WPP) på, eller intillrenbetesmarker. Denna avhandling undersöker diskursen kring en WPP byggd i Härjedalen för IKEA. WPP byggdes på Glötesvålen, ett låg-fjäll som tidigare haft strategiskt viktiga betesmarker för samebyn Mittådalen. Genom en dissektion av elektroniska källor och halvstrukturerade intervjuer genomför författaren en diskursanalys för att identifiera de vanligaste narrativen om IKEAs vindkraftpark på Glötesvålen. En induktiv metod används för att identifiera underliggande ideologier som finns i diskursen genom ett relevant teoretisk ramverk. Resultaten visar en genomgripande entusiasm för vindkraft som ett steg mot förnybar energi. Detta narrativ speglar ideologin för ekologisk modernisering. Resultaten hittar också ett kritisk narrativ som lyfter den ojämna maktdynamiken som renskötarna upplever. Detta förstås genom Spivaks (2010) "Kan den underordnade tala?". Ytterligare en diskurs som upptäcks är symbolfrågan mellan industriell ekologisk omställning och bevarandet av renskötseln som kulturarv.
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Thuo, Njeri. „The synthesis and characterization of poly[oxo(2-chloro-1, 4-phenylene) oxy terephthaloyl-co-(2chloro-1, 4-oxy carbonyl methylene oxo terephthayoly-co oxy(2-chloro-1, 4-phenylene methylene oxy oxy terephthaloyl]“. DigitalCommons@Robert W. Woodruff Library, Atlanta University Center, 1992. http://digitalcommons.auctr.edu/dissertations/1617.
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Two copolyesters were prepared in the melt from terephthalic acid, 1,4- phenylenediacetic acid, 2-chlo~ 1,4-phenylenediacetate and CXCX -diacetoxy-I ,4- phenylene. Neither polymer is observed to exhibit liquid crystalline properties. Polymer I has an inherent viscosity of O.39g/dl while polymer 2 has an inherent viscosity of O.64g/dl. The Thermal properties of both polymers are obtained. Thermogravimetric analysis result indicate that polymer I starn to loose weight at 2750 C, while polymer 2 which is more thermally stable only losses less than 5% of it's weight at 3500 C. Both polymers were characterized by FT-IR, lH NMR and 13c NMR, POM, DSC, TGA and viscosity.
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Boscaro, Mateus Eugenio. „Determinação de elementos químicos em plásticos biodegradáveis naturais e sintéticos“. Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/64/64134/tde-26012015-144429/.
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Preocupações com o acúmulo de lixo plástico e seu consequente impacto ambiental levaram os cientistas e a indústria química, nas últimas décadas, a uma busca por plásticos biodegradáveis e plásticos produzidos com matérias-primas de fontes renováveis. Entre eles, encontram-se o poli(ácido lático), o poli(?-caprolactona), os poli(hidroxialcanoatos), os polímeros de amido e os polímeros sintéticos que recebem aditivos que facilitam a degradação, conhecidos como oxi-biodegradáveis. Em decorrência dos processos de produção e uso de aditivos e corantes, os plásticos podem conter constituintes que não fazem parte das moléculas do polímero. Por esta razão, o objetivo do trabalho foi determinar os elementos químicos presentes em amostras de polímeros biodegradáveis, sacolas oxi-biodegradáveis e sacolas de amido distribuídas em supermercados, empregando-se análise por ativação neutrônica instrumental (INAA) e espectroscopia de fluorescência de raios X (XRF). A identificação dos polímeros das sacolas de supermercado foi realizada por espectroscopia de absorção no infravermelho com transformada de Fourier (FTIR). Os resultados das análises químicas dos polímeros não processados evidenciaram baixas concentrações dos elementos químicos. Já os plásticos das sacolas apresentaram altas concentrações de cálcio, sódio, zinco e titânio, provenientes do uso de cargas minerais, corantes e outros aditivos. Em algumas amostras, as concentrações de zinco, cobalto, cromo, molibdênio e chumbo excederam os limites estabelecidos pela norma ABNT NBR 15448-2:2008 para polímeros biodegradáveis. As análises também indicaram que os aditivos pró-oxidantes utilizados nas sacolas oxi-biodegradáveis são baseados em compostos químicos que contêm ferro. Os resultados obtidos comprovam que os plásticos biodegradáveis podem ser utilizados de forma segura em embalagens e outras aplicações, desde que se evitem os aditivos contendo elementos químicos tóxicos e outras substâncias perigosasConcerns about the accumulation of plastic waste and its consequent environmental impact have led scientists and chemical industry, in recent decades, to search for biodegradable plastics and plastics made with renewable raw materials. Among them are included poly (lactic acid), polycaprolactone, polyhydroxyalkanoates, starch polymers and synthetic polymers having additives which facilitate degradation, known as oxo-biodegradable. Due to production processes and use of additives and dyes, plastics may contain small amounts of chemical elements that are not part of the polymer molecules. For this reason, the objective of this study was to determine chemical elements in samples of biodegradable polymers, oxy-biodegradable and starch bags distributed in supermarkets by instrumental neutron activation analysis (INAA) and X-ray fluorescence spectroscopy (XRF). The polymers of plastic bags were identified by Fourier transform infrared spectroscopy (FTIR). Results of chemical analysis of unprocessed polymers have shown low concentrations of chemical elements. On the other hand, plastic bags have high concentrations of calcium, sodium, zinc and titanium, from the use of mineral fillers, dyes and other additives. In some bag samples, the concentration of zinc, cobalt, chromium, molybdenum and lead exceeded the limits established by the ABNT NBR 15448-2:2008 for biodegradable polymers. The analysis also indicated that the pro-oxidant additives used in the oxy-biodegradable bags are based on chemical compounds that contain iron. These results demonstrate that biodegradable plastics can be safely used in packaging and other applications, provided additives containing toxic chemical elements and other hazardous substances are avoided
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Benincasa, Fabio. „DETERMINAÇÃO RÁPIDA E AUTOMÁTICA DE AÇÚCARES REDUTORES EM CALDO DE CANA-DE-AÇÚCAR“. Universidade do Oeste Paulista, 2012. http://bdtd.unoeste.br:8080/tede/handle/tede/404.
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Previous issue date: 2012-05-21The monosaccharides (glucose and fructose) present in the sugarcane are reducing sugars because they have free carbonyl group, able to oxidize in the presence of oxidizing agents. The classical analytical methods (Lane-Eynon, Benedict, EDTA complexometric-, the Luff-Schoorl method, Musson-Walker, Somogyi-Nelson) based on the reduction of copper ions in alkaline solutions. Some industries use sucroalcooleiras methodology Lane-Eynon, other apparatus REDUTEC®, and others perform the calculation of RS (reducing sugar). The aim of this study was to understand the relationship between the variation of electric conductivity measurement in millivolts, mass wears and concentration of RS, with equipment similar to that proposed by Horii and Gonçalves, properly adapted, tested mathematical models with broth of sugar cane and held the automation of analyses. We used the apparatus REDUTEC ®, digital scales, peristaltic pump, digital camcorder, graphics and mathematical programs. It is concluded that there is a mathematical correlation between electrical conductivity (mv), RS. The mathematical model is statistically efficient solution of low concentration of RS (<0.3%).
Os monossacarídeos (glicose e frutose) presentes na cana-de-açúcar são açúcares redutores por possuírem grupo carbonílico livres, capazes de se oxidarem na presença de agentes oxidantes. Os métodos analíticos clássicos (Lane-Eynon, Benedict, complexométrica-EDTA, Luff-Schoorl, Musson-Walker, Somogyi-Nelson) baseiam-se na redução de íons cobre em soluções alcalinas. Algumas indústrias sucroalcooleiras utilizam a metodologia de Lane-Eynon, outras o aparelho REDUTEC® e outras realizam o calculo de AR (açúcares redutores). O objetivo do presente estudo foi compreender a relação entre a variação da condutividade elétrica medida em milivoltagem, massa gasta e concentração de AR, com aparelho semelhante ao proposto por Horii e Gonçalves, devidamente adaptado, testou-se modelos matemáticos com caldos de cana-de-açúcar e realizou-se a automação das análises. Utilizou-se o aparelho REDUTEC®, balança digital, bomba peristáltica, câmera de vídeo digital, programas matemáticos e gráficos. Conclui-se que existe uma correlação matemática entre condutividade elétrica (mv), massas gasta e AR, O modelo matemático gerado é eficiente estatisticamente, para solução de baixa concentração de AR (< 0,3%).
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Langlet, Abraham. „Nitration of Oxo-pyramidines and Oxo-imidazoles“. Doctoral thesis, KTH, Kemi, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-601.
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This thesis is mainly focused on the reactions of oxo-pyrimidines and oxo-imidazoles with nitric acid in sulfuric acid and properties of the gem-dinitro products formed in this process. Low temperature nitrations of 2-methylimidazoles produced – in addition to the known 2-methyl-5(4)-nitroimidazole – 2-(dinitromethylene)-5,5-dinitro-4-imidazolidinone and parabanic acid. This tetranitro compound was also obtained via nitration of 2-methyl-4,4-dihydro-(1H)-5- imidazolone. Thermal decomposition of 2-(dinitromethylene)-5,5-dinitro-4-imidazolidinone yielded 2-(dinitromethylene)-4,5-imidazolidinedione, which also was the product from the nitration of the new compound 2-methoxy-2-methyl-4,5-imidazolidienedione. Treatment of 2- (dinitromethylene)-5,5-dinitro-4-imidazolidinone with aqueous ammonia resulted in the previously unknown 1,1-diamino-2,2-dinitroethylene (Paper I). The nitration of some 2-substituted pyrimidine-4,6-diones in sulfuric acid, which afforded previously unknown 5,5-gem-dinitro-pyrimidine-4,6-diones in high yields, was studied. Alloxane was prepared in a one-step procedure by thermal decomposition of 5,5-dinitrobarbituric acid in hot acetic acid. The gem-dinitro products were found to be easily attacked by nucleophiles with concomitant formation of gem-dinitroacetyl derivatives, which in turn could be further hydrolysed to salts of dinitromethane and triureas (Papers II and III). Nitration of 4,6-dihydroxypyrimidine in sulfuric acid yielded nitroform as the sole product. This behaviour was tentatively explained by the formation of an intermediate, 5,5-dinitro-4,6- dihydroxypyrimidine, which underwent hydrolysis in the nitrating acid into gem-dinitroacetyl formamidine. This compound was further nitrated in the same reaction mixture into trinitroacetylformamidine, which finally underwent hydrolytic cleavage into nitroform. It was also demonstrated that gem-dinitroacetylureas could produce nitroform upon nitration. The structures of the proposed trinitroacetylureas were confirmed by the isolation of one of their derivatives (Paper IV).QC 20100907
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Langlet, Abraham. „Nitration of oxo-pyrimidines and oxo-imidazoles /“. Stockholm, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-601.
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Pohlmann, Juliana Gonçalves. „Avaliação da reatividade ao CO2 de chars obtidos em atmosferas convenional (O2/N2) e de oxi-combustão (O2/CO2) com vistas à aplicação no alto-forno“. reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2010. http://hdl.handle.net/10183/27923.
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A injeção de carvão pulverizado - PCI - é praticada nas ventaneiras dos altos-fornos com o objetivo de substituir parcialmente o coque, provendo energia e gases redutores ao processo. Em geral, as melhorias desse processo ocorrem no sentido de diminuir o fuel rate e aumentar a produtividade do alto-forno. A tecnologia de oxi-combustão consiste na queima de carvão em uma atmosfera livre de N2, o qual é substituído por um gás rico em CO2. Visando a possibilidade de aplicação desta tecnologia em PCI, chars de três carvões de diferentes ranks utilizados para injeção e chars de um coque de petróleo foram obtidos em atmosferas convencional (O2/N2) e de oxi-combustão (O2/CO2) em forno de queda livre O objetivo do presente trabalho foi avaliar a reatividade ao CO2 desses chars por termogravimetria via método isotérmico a 1000°C. Resultados de eficiência da combustão (burnout), de área superficial e a morfologia dos chars antes da gaseificação auxiliaram a análise da reatividade. A reatividade foi, em geral, mais alta quanto mais baixo o rank do carvão e tendeu a aumentar com o burnout, o qual foi associado ao aumento na área superficial BET. Em geral, as reatividades ao CO2 dos chars de atmosferas O2/N2 e O2/CO2, obtidos com o mesmo teor de oxigênio, não apresentaram diferenças significativas. Apenas no caso dos chars do carvão de mais baixo rank e obtidos em maior teor de oxigênio é que as amostras de oxi-combustão foram mais reativas.Pulverized coal injection (PCI) is used in the blast furnace tuyeres attempting to provide energy and reducing gases to the process. New technologies have been studied to improve PCI and to make ironmaking process suitable to environmental requirements. Oxy-fuel combustion technology consists of burning coal in a N2-free atmosphere, which is exchanged by a CO2-rich gas. Aiming at a possible application of oxy-fuel combustion in blast furnace, chars of three typical PCI coals of different ranks were obtained under conventional (O2/N2) and oxy-fuel (O2/CO2) atmospheres in drop tube furnace. The aim of this work was to evaluate the CO2 reactivity of these chars via thermogravimetric analysis by isothermal method at 1000ºC. Coals burnouts, BET surface areas of chars and chars morphology before gasification gave support in the reactivity results analyse. In general, the higher reactivities were observed for the lower rank coal chars. Reactivity increased when coal burnouts and chars BET surface areas also increased. The CO2 reactivities of conventional and oxy-fuel chars, obtained under the same oxygen content, have not shown significant differences.
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Franco, Alexandre. „Nitro- e oxi-HPA no material particulado atmosférico: algumas contribuições para uma abordagem integrada“. Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/46/46133/tde-05122006-144151/.
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Os derivados nitrados e oxigenados de hidrocarbonetos policíclicos aromáticos, nitro-HPA e oxi-HPA, podem ser encontrados no material particulado atmosférico e são provenientes da queima de combustíveis fósseis e biomassa, ou de reações dos HPA com gases atmosféricos. Determinados nitro-HPA e oxi-HPA apresentam mutagenicidade mais elevada do que a dos seus HPA precursores. O presente trabalho teve como objetivo avaliar os níveis de nitro-HPA e oxi-HPA nos extratos orgânicos do material particulado atmosférico das cidades de São Paulo, Araraquara, Paulínia e Piracicaba, durante períodos com e sem a queima da palha da cana-de-açúcar, verificar a possível existência de transporte de poluentes entre as regiões estudadas e determinar a mutagenicidade do material particulado. O material particulado atmosférico foi coletado em amostrador de grande volume com filtro de fibra de quartzo e extraído em Soxhlet. Os extratos foram submetidos à separação por HPLC, obtendo as frações de HPA, nitro-HPA e oxi-HPA, as quais foram analisadas por GC-MS. Tanto as frações como os extratos brutos foram submetidos a determinações gravimétricas e testes biológicos. Os nitro-compostos específicos, 1-nitropireno (1-NPir), 3-nitrofluoranteno (3-NFlt) e 6-nitrocriseno (6-NCri), para os quais há disponibilidade de padrões, foram analisados sendo que o 6-NCri não foi detectado em nenhuma amostra. Os níveis dos nitro-HPA encontrados (concentração máxima = 0,86 ngm-3) foram similares aos níveis reportados na literatura para diferentes cidades do mundo e o 3-NFlt apresentou níveis mais altos do que o 1-NPir em todas as amostras. Dentre os sítios estudados, São Paulo apresentou, em geral, níveis mais altos do que Araraquara, Piracicaba e Paulínia, apesar das concentrações altas de material particulado encontradas nesses três sítios. Em todos os sítios estudados houve um aumento nos níveis dos nitro-HPA no inverno, e não foi possível verificar se as emissões provenientes da queima da palha da cana-de-açúcar contribuem para os níveis desses poluentes. Na cidade de São Paulo, sítio mais estudado, foi observada uma variação sazonal evidenciada pelo aumento dos nitro-HPA no inverno de 2002. Níveis similares de nitro-HPA foram observados nos invernos de 2001 a 2004, exceto em 2003, onde os níveis foram mais altos devido provavelmente ao período longo de estiagem e às condições meteorológicas favoráveis à estagnação dos poluentes. Relacionando-se os níveis dos nitro-HPA com as trajetórias das massas de ar verificou-se um possível transporte de poluentes de uma região para outra em um único caso, de um total de 15. Dentre os oxi-HPA identificados (5H-fenantro(4,5-bcd)pirano-5-ona, 1-ácido fenantrenocarboxílico, 4H-ciclopenta(def)criseno-4-ona, 9,10-antracenodiona e benzantrona) a 9,10-antracenodiona e a benzantrona são comprovadamente mutagênicos. A benzantrona foi a mais freqüentemente encontrada nas amostras. Os níveis mais altos de oxi-HPA foram encontrados nas amostras de Araraquara e Piracicaba. Por final, pode-se concluir também, que as mutagenicidades das frações nitro- e oxi-HPA são as principais responsáveis pela mutagenicidade do extrato bruto, uma vez que a mutagenicidade das frações HPA praticamente não contribuiu para a mutagenicidade total.Nitrated and oxygenated derivatives of polycyclic aromatic hydrocarbons, nitro-PAH and oxi-PAH, can be found in the atmospheric particulate matter from the combustion of fossil fuel and biomass or as result of PAH reactions with atmospheric gases. Some nitro-PAH and oxi-PAH compounds present higher mutagenicity than their parent PAH. The objective of this research was to evaluate the nitro- and oxi-PAH levels in organic extracts of atmospheric particulate matter collected at the cities of Sâo Paulo, Araraquara, Piracicaba and Paulinia, over periods with and without sugar cane burning, to analyze the possible transport of pollutants at these regions and to determine the mutagenicity of the particulate matter . The atmospheric particulate matter was collected by high volume sampler over quartz fiber filter and extracted with soxhlet. Extracts were submited to HPLC to obtain PAH, nitro-PAH and oxi-PAH fractions, which were analyzed by the GC-MS. Both fractions and extracts were subjected to gravimetric determinations and biological tests. Specific compounds, 1-nitropyrene (1-NPir), 3-nitrofluoranthene (3-NFlt) and 6-nitrocrisene (6-NCri) were analyzed and only 6-NCri was not detected in any of the samples. The determined levels of nitro-PAH (maximum concentration = 0,86 ngm-3) were similar to that reported in the literature for other cities of the world. In all samples, the 3-NFlt level was higher than that of 1-NPir. Among the studied areas, São Paulo presented, in general, higher levels than Araraquara, Piracicaba and Paulinia, despite the high concentration of particulate matter found at these areas. All the studied sites presented higher levels of nitro-PAH during the winter, and it was not possible to verify if the emissions of sugar cane burning contribute to the levels of these pollutants. An increase of the nitro-PAH during the winter of 2002 was observed in São Paulo, the more deeply studied site, showing a seasonal variation. Similar levels of nitro-PAH were observed in the winter of 2001, 2002 and 2004. In 2003, the levels were even higher probably due to the long period without rain and favorable meteorological conditions to the stagnation of pollutants. Relating the nitro-PAH levels with the air masses trajectories, it was observed that the pollutants were transported from a region to another in only one out of the 15 studied cases. Among the oxi-PAH identified (5H-phenanthro(4,5-bcd)pyran-5-one, 1-phenanthene carboxylic acid, 4H-ciclopenta(def)crisene-4-one, 9,10-anthracenedione and benzanthrone), the 9,10-anthracenedione and benzanthrone are mutagenic and were found in the most of the samples. Finally, the mutagenicity of the nitro-PAH and oxi-PAH fractions accounted for the mutagenicity of the organic extract, due to the fact that the mutagenicity of the PAH fractions was very low and its contribution to the total mutagenicity was negligible.
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Pereira, Daniela Cristina de Almeida. „Poluição em ambientes internos. Caracterização de espécies no material particulado de atmosferas escolares“. Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-12042018-094059/.
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Atualmente a poluição do ar é um assunto relevante para a população e para os órgãos governamentais, em razão dos efeitos na saúde e no clima. Tão importante quanto a quantidade de material particulado na atmosfera, é também, a sua composição. O objetivo deste estudo foi determinar a concentração de MP10 e espécies orgânicas e inorgânicas em amostras coletadas em ambientes internos e externos de três escolas do Estado de São Paulo, para avaliar a qualidade do ar. As concentrações de MP10 foram determinadas por gravimetria, depois foram submetidas à extração, rotaevaporação, fracionamento em coluna, e os compostos foram determinados através da cromatografia gasosa acoplada ao espectrômetro de massas; o carbono elementar e o carbono orgânico foram determinados pelo método termo-óptico, pelo sistema desenvolvido na Universidade de Aveiro; o carbono grafítico foi determinado por refletometria e os metais por EDXRF e algumas amostras foram analisadas por cromatografia de íons, no instituto de Astronomia, Geofísica e Ciências Atmosféricas da Universidade de São Paulo. As amostras de MP10 foram coletadas nos seguintes sítios: (i) escola de Aplicação, dentro da Cidade Universitária, de área urbana que sofre influência de via de grande movimento de veículos e da vegetação local; (ii) escola Madalena de Almeida do Cais, na cidade de Nova Granada localizada a cerca de 475 quilômetros da cidade de São Paulo, com baixa população e poucos veículos; (iii) escola particular em bairro residencial da zona oeste, que sofre a influência de avenida com grande fluxo de veículos. Os resultados indicaram que a concentração do MP10 foi mais alta em ambiente interno que externo na escola dentro da USP. Na escola particular, a concentração mediana apontou que o ambiente externo apresentou concentração de MP10 superior ao ambiente interno. Para os hidrocarbonetos policíclicos aromáticos, observou-se que tanto na escola do interior quanto na escola do campus, houve maior concentração em ambiente interno, e alguns de maior peso molecular, atribuídos às emissões veiculares, foram mais altos em ambiente externo. As razões diagnósticas indicaram queima de combustíveis fósseis ao redor dos sítios amostrados. As amostras coletadas nas escolas apresentaram baixos riscos à saúde. Os compostos 2- metilantraquinona e benzo(a)antraceno-7,12-diona foram encontrados nas amostras, denotando a influência da exaustão veicular. A fração carbonácea (EC + OC) apresentou maior concentração em ambiente externo, e a razão OC/EC para o ambiente externo apontou para a queima de biomassa. A fonte de carbono grafítico corroborou a influência do tráfego. Para a maioria dos elementos, com exceção do cromo, manganês e ferro, as concentrações obtidas em ambiente interno foram as mais altas, majoritariamente oriundos da ressuspensão do solo. O cromo e o manganês estão relacionados com a emissão dos veículos que utilizaram a mistura gasolina e etanol; o ferro, com a crosta terrestre. Para os íons, a concentração média para ambientes externos apresentou a seguinte tendência: SO42- > NO3- > Ca2+ > NH4+ > Na+ > K+> Mg2+ > Cl- e para ambientes internos foi Ca2+ > SO42- > NO3- > Na+ > NH4+ > K+ > Cl- > Mg2+ > F-. A maioria das espécies apresentou a influência da ressuspensão do solo; o nitrato e o sulfato foram atribuídos à emissão veicular, e o cátion amônio foi formado por reações a partir da degradação da matéria orgânica e dos processos que ocorrem nos catalisadores veiculares.Nowadays, air pollution is a relevant issue for people and government agencies because of the health and climate effects. As important as the amount of particulate matter in the atmosphere, is also, its composition. The object of this study was to determine the concentration of PM10 and organic and inorganic species in samples collected in indoor and outdoor environment of three schools in the State of São Paulo, to evaluate air quality. The concentrations of PM10 were determined by gravimetry, then the samples were subjected to extraction, rotary evaporation, column fractionation, and the compounds were determined by gas chromatography coupled to the mass spectrometer; elemental carbon and organic carbon were determined by the thermooptical method, by the system developed at the University of Aveiro; the graphitic carbon was determined by reflectometry and the metals by EDXRF and some samples were analyzed by ion chromatography, at the Institute of Astronomy, Geophysics and Atmospheric Sciences of the University of São Paulo. PM10 samples were collected at the following sites: (i) school of Application, within the University City, an urban area that is influenced by a large vehicular route and local vegetation; (ii) Madalena de Almeida do Cais school, in the city of Nova Granada located about 475 kilometers from the city of São Paulo, with low population and few vehicles; (iii) private school in a residential neighborhood in the western zone, which suffers the influence of avenue with a large flow of vehicles. The results indicated that PM10 concentration was higher in indoor than outdoor environment in the school within USP. In the private school, the median concentration indicated that the outdoor environment presented a concentration of PM10 higher than the indoor environment. For the polycyclic aromatic hydrocarbons, it was observed that both countryside school and campus school, a higher concentration of compounds in the indoor environment was found, only some high molecular weight compounds, attributed to vehicular emissions, were higher in the external environment. Diagnostic ratios indicated the burning of fossil fuels around the sites sampled. Samples collected in schools presented low health risks. 2-methylanthraquinone and benzo(a)anthracene-7,12-dione were found in the samples, denoting the influence of vehicle exhaust. The carbonaceous fraction (EC + OC) presented higher concentration in the outdoor environment and OC/EC ratio for the outdoor environment pointed to biomass burning. The graphite carbon source corroborated the traffic influence. For most of the elements, except for chromium, manganese and iron, the concentrations obtained in indoor environment were the highest, mainly derived from soil resuspension. Chromium and manganese are related to the emission of the vehicles that used the mixture gasoline and ethanol; iron is from the terrestrial crust. For the ions, the average concentration for outdoor environments presented the following trend: SO42-> NO3-> Na+> NH4+> Na+> K+> Mg2+> Cl- and for indoor environments was Ca2+> SO42-> NO3-> Na+ > NH4+> K+ > Cl-> Mg2+> F-. Most of the species showed the influence of soil resuspension; nitrate and sulfate were attributed to human activities, i. e., vehicular emission, and, the ammonium cation was formed by reactions from the degradation of the organic matter and the processes that occur in vehicular catalysts.
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Yau, K. C. „The asymmetric synthesis of oxo-piperidines and oxo-pyrrolidines“. Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1451240/.
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Chapter 1 describes the attempts to synthesize piperidin-2-ones via an aza-Michael-Michael annulation, which were unsuccessful. A general route for the synthesis of piperidin-2,4-diones from β-keto esters via a Dieckmann cyclisation was proposed and five piperidin-2,4-diones with different substituents at positions-5 and -6 were prepared. An asymmetric route to 1-unsubstituted piperidin-2,4-diones was also developed which involved the use of Davies' chiral auxiliary to induce an asymmetric Michael addition. Chapter 2 describes a new approach to the synthesis of codeine. The piperidin-4-one ring was prepared by a Dieckmann cyclisation; a Robinson annulation was performed to construct the cyclohexenone ring and the key bicyclic intermediate was made. However, attempts to prepare the corresponding benzomorphan via a Grewe cyclisation of the α,β-unsaturated ketone were not successful. Synthesis of various 2,3-disubstituted piperidin-4-ones using the same strategy as the codeine synthesis was attempted; six different piperidin-4-ones with alkyl and aryl substituents at the 2-position were prepared. Chapter 3 describes the attempts to synthesize 1,2-dihydropyrrol-3-ones employing the same strategy used to make piperidin-4-ones in Chapter 2. Seven different diester intermediates were successfully prepared but attempts for Dieckman cyclisation failed. The focus was changed to prepare 5-substituted pyrrolidin-3-ones by the protocol used to make piperidin-2,4-diones in chapter 1 and four pyrrolidin-3-ones were made. Enantioselective syntheses using the Davies' chiral auxiliary were attempted and enantiopure 5-methylpyrrolidin-3-one was prepared.
Bücher zum Thema "OX2"
1
Guasp, Joan. Oxo. Madrid: Fundación Autor, 1997.
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2
Alferi, Pierre. Oxo. Providence, RI: Burning Deck, 2004.
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3
Kotsōnēs, Christos K. Oxō Manē. Athēna: Milētos, 2011.
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4
Wijn, H. P. J., Hrsg. Oxy-Spinels. Berlin/Heidelberg: Springer-Verlag, 1991. http://dx.doi.org/10.1007/b41057.
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Oxō Manē. Athēna: Milētos, 2011.
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Aserbaidschanische Chrestomathie: Oxū = Oxu : Texte aus Nord- und Südaserbaidschan unter Berücksichtigung der Besonderheiten des Nord- und Südaserbaidschanischen. Engelschoff: Auf dem Ruffel, 2001.
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7
Oxū at! Yāyīn gīzlat! Tabrīz: Nashr-i Akhtar, 2011.
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Frey, Guido, und Georg Dämbkes. 75 Jahre Oxo-Synthese. Herausgegeben von OXEA GmbH. Essen: Klartext, 2013.
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Santelia, Stefania. Charition liberata (P. Oxy. 413). Bari: Levante Editori, 1991.
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Santelia, Stefania. Charition liberata (P. Oxy. 413). Bari: Levante, 1991.
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1
Jacobson, Laura H., Sui Chen, Sanjida Mir und Daniel Hoyer. „Orexin OX2 Receptor Antagonists as Sleep Aids“. In Behavioral Neuroscience of Orexin/Hypocretin, 105–36. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/7854_2016_47.
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Yeager, M. P. „Continuous $$S\bar v{O_2}$$ O2 Monitoring“. In Update in Intensive Care and Emergency Medicine, 229–32. Berlin, Heidelberg: Springer Berlin Heidelberg, 1986. http://dx.doi.org/10.1007/978-3-642-82801-0_38.
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Gooch, Jan W. „Oxy-“. In Encyclopedic Dictionary of Polymers, 511. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_8332.
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Curley, Martin, und Bror Salmelin. „Framing OI2“. In Open Innovation 2.0, 47–51. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-62878-3_5.
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Gooch, Jan W. „Oxo Process“. In Encyclopedic Dictionary of Polymers, 511. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_8331.
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Li, Jie Jack. „Cope, oxy-Cope, and anionic oxy-Cope rearrangements“. In Name Reactions, 75–76. Berlin, Heidelberg: Springer Berlin Heidelberg, 2002. http://dx.doi.org/10.1007/978-3-662-04835-1_63.
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Li, Jie Jack. „Cope, oxy-Cope, and anionic oxy-Cope rearrangements“. In Name Reactions, 84–85. Berlin, Heidelberg: Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-662-05336-2_68.
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Moser-Jauslin, L. „$$O_2(\mathbb {C})$$O2(C)-Vector Bundles and Equivariant Real Circle Actions“. In Polynomial Rings and Affine Algebraic Geometry, 209–21. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-42136-6_9.
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Vender, J. S. „Continuous $$S\bar v{O_2}$$ O2 Monitoring in Respiratory Intensive Care Patients“. In Update in Intensive Care and Emergency Medicine, 202–6. Berlin, Heidelberg: Springer Berlin Heidelberg, 1986. http://dx.doi.org/10.1007/978-3-642-82801-0_33.
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Choi, C. G., I. H. Na, J. W. Lee, T. Y. Chae und W. Yang. „The Effects of De-humidification and O2 Direct Injection in Oxy-PC Combustion“. In Cleaner Combustion and Sustainable World, 1239–41. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-30445-3_163.
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Turner, Mattias A., Tyler Paschal, Waruna D. Kulatilaka und Eric L. Petersen. „An Investigation of Laminar Flame Speed of CH4-O2-CO2 Mixtures“. In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-91392.
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Abstract The push for lower carbon emissions in power generation has driven interest in methods of carbon capture and sequestration. One such promising method involves the supercritical CO2 (sCO2) power cycle, a system which is powered by oxy-fuel combustion where supercritical carbon dioxide is used as the working fluid. The high CO2 concentration in the combustion products allows for relatively simple extraction of CO2 from the system. Although this is an active field of research, the design of such a combustor requires continued study of oxy-fuel combustion in high levels of CO2 diluent. With that objective in mind, laminar flame experiments were conducted for CH4-O2-CO2 mixtures at one atmosphere and room temperature, where the relative concentrations of O2 and CO2 in the oxidizer mixture were 34.0% and 66.0% by mole, respectively. These concentrations were chosen to ensure the flame would propagate quickly enough to overcome the effects of buoyancy, which were observed to become significant below laminar flame speeds of roughly 15 cm/s. A high-speed chemiluminescence imaging diagnostic was employed in place of the traditional schlieren technique. Laminar flame speed was measured from OH* emission at 306 nm for a full range of equivalence ratios, varying from 15.2 cm/s at 0.7 to 24.8 cm/s at stoichiometric. Additionally, images of OH* chemiluminescence of turbulent CH4-O2-CO2 flames and of quiescent, 5-atm CH4-O2-CO2 flames at stoichiometric concentration are also presented. These experiments provide useful data for validation of chemical kinetics models for oxy-methane combustion in a CO2 diluent, which can be applied to the modeling of oxy-methane combustion for supercritical CO2 power cycles.
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Saravanan, V., Arun Aravind, Sreenivas Jayanti und Ramakrishna. „Burning Profile of High Ash Indian Coals in Oxy-Fuel Environment“. In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-67185.
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Oxy-fuel combustion is one of the emerging technologies to capture and store CO2 emissions generated from thermal power plants. Research programs are in full swing to find out the possibility of retrofitting existing coal fired power plants with oxy-fuel mode combustion. Most of the Indian thermal power plants are pulverized coal based and use sub-bituminous Indian coals. These coals differ from the foreign coals in respect of maceral composition, ash content and combustion kinetics. It is imperative to understand the burning characteristics of Indian coals in oxy-fuel environment to evolve the suitable design for the retrofit of Indian boilers with oxy-fuel mode for the efficient and economic carbon capture without losing thermal efficiency. The present study involves the assessment of the kinetics of pyrolysis and char oxidation of three different Indian coals with varying ash contents viz. 33 to 44% in normal air and in oxy-fuel environment with three different CO2/O2 concentrations (60:40, 70:30 and 80:20) by Thermo Gravimetric method (TGA). The results are compared in respect of weight loss pattern, peaking temperatures and weighted mean activation energy. The results have shown that the combustion kinetics of the selected high ash Indian coals in normal air combustion is more comparable with 70:30 and 80:20 than 60:40 CO2/O2 concentrations. The methodology adopted in the present study is found useful for comparing the combustion kinetics of various types of coals in normal air and oxy-fuel environment.
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Saravanan, V., Sreenivas Jayanti und Subramanyam Seetharamu. „Optimization of a Coal-Fired Furnace for Oxy Fuel Combustion“. In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-67181.
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Oxy-fuel combustion, in which a conventional hydrocarbon fuel is burned in presence of oxygen diluted with carbon dioxide (called henceforth as oxy-fuel), is an emerging technology that accommodates CO2 sequestration while offering the prospect of low emissions. Dilution by CO2 (from flue gas recirculation) prevents high peak temperatures thereby reducing material damage, high NOx formation etc. Studies [1] reveal that CO2-diluted flames are unstable as compared to N2-diluted flames and that a higher molar fraction of oxygen, 30% by volume, is necessary to ensure stable combustion. Nevertheless, as the heat transfer properties of CO2/O2–70:30 mixtures are different to that of normal air, the flow profiles and heat flux distributions might vary within the furnace. While considering the retrofit of existing normal air operated coal fired furnaces with oxy-fuel mode, it is imperative to investigate these flow variations in detail. In the present study, Computational Fluid Dynamics (CFD) based simulations have been done for a typical 210 MW Indian pulverized coal fired furnace under normal air combustion and under oxy-fuel combustion (CO2/O2-70:30 volume %) mode and the results in terms of CO2 concentration, temperature distribution, velocity of flue gas, particle trajectories and devolatilisation characteristics have been compared.
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Mazas, A. N., D. A. Lacoste und T. Schuller. „Experimental and Numerical Investigation on the Laminar Flame Speed of CH4/O2 Mixtures Diluted With CO2 and H2O“. In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22512.
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The effects of CO2 and H2O addition on premixed oxy-fuel combustion are investigated with experiments and numerical simulations on the laminar flame speed of CH4/O2/CO2/H2O(v) and CH4/O2/N2/H2O(v) mixtures, at atmospheric pressure and for a reactants inlet temperature Tu = 373 K. Experiments are conducted with steady laminar conical premixed flames over a range of operating conditions representative of oxy-fuel combustion with flue gas recirculation. The relative O2-to-CO2 and O2-to-N2 ratios, respectively defined as O2/(O2+CO2) (mol.) and O2/(O2+N2) (mol.), are varied from 0.21 to 1.0. The equivalence ratio of the mixtures ranges from 0.5 to 1.5, and the steam molar fraction in the reactive mixture is varied from 0 to 0.45. Laminar flame speeds are measured with the flame area method using a Schlieren apparatus. Experiments are completed by simulations with the PREMIX code using the detailed kinetic mechanism GRI-mech. 3.0. Numerical predictions are found in good agreement with experimental data for all cases explored. It is also shown that the laminar flame speed of CH4/O2/N2 mixtures diluted with steam H2O(v) features a quasi-linear decrease when increasing the diluent molar fraction, even at high dilution rates. Effects of N2 replacement by CO2 in wet reactive mixtures are then investigated. A similar quasi-linear decrease of the flame speed is observed for CH4/O2/CO2 H2O-diluted flames. For a similar flame speed in dry conditions, results show a larger reduction of the burning velocity for CH4/O2/N2/H2O mixtures than for CH4/O2/CO2/H2O mixtures, when the steam molar fraction is increased. Finally, it is observed that the laminar flame speed of weakly (CO2, H2O)-diluted CH4/O2 mixtures is underestimated by the GRI-mech 3.0 predictions.
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Amato, Alberto, Robert Hudak, David R. Noble, David Scarborough, Peter A. D’Carlo, Jerry M. Seitzman und Tim C. Lieuwen. „Methane Oxy-Combustion for Low CO2 Cycles: Measurements and Modeling of CO and O2 Emissions“. In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22300.
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Concerns about green house gas emissions have encouraged interest in hydrocarbon combustion techniques that can accommodate carbon dioxide capture and sequestration. Oxy-fuel combustion, where the fuel is combusted in oxygen diluted with steam or CO2, is seen as one promising approach. In this paper we focus on CO2 dilution effects and, in particular, on CO and O2 emissions from these flames. The emissions issue must be considered from a different perspective than conventional power plants as the combustor effluents will be sequestered, and, thus, their interactions with the terrestrial atmosphere are not relevant. Equilibrium CO emissions from CO2 diluted systems are much higher than conventional air systems. In addition, for carbon sequestration application, pipeline specifications impose limitations on CO and O2 levels which also must then be controlled. Equilibrium and kinetic modeling of CH4/O2/CO2 combustion systems was performed in order to analyze CO2 dilution effects upon CO and O2 emissions level. Companion experiments were also performed in an atmospheric pressure, swirl stabilized combustor. These numerical and experimental results quantify the strong dependence of emissions on stoichiometry, CO2 dilution and residence time.
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Qian, Wenkai, Haoyang Liu, Min Zhu und Suhui Li. „Kinetics Study of a Staged Combustor Concept for Oxy-Fuel Combustion Gas Turbine Cycles“. In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-90599.
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Abstract Oxy-fuel combustion has been identified as a promising technology for CO2 capture and NOx reduction. It has great potential to be applied in gas turbine cycles. Previous studies, however, reveal that simple oxy-fuel combustors suffer from issues like flame blowoff and CO emissions especially at part load, due to the high CO2 content in the combustion atmosphere. In this paper, a staged combustor concept is proposed to mitigate flame blowoff and CO emissions issues for load operations. The conceptual combustor consists of three zones axially: primary zone, CO burnout zone, and dilution zone. All fuel is fed to the primary zone, while O2 is distributed to the primary zone and CO burnout zone. CO2 is distributed to the primary zone and dilution zone. By adjusting the distribution of the O2 and CO2, the primary zone operates at a relatively higher flame temperature at part load, which helps improve the flame blowoff performance. A chemical reactor network model is developed to study the effects of key design/operating parameters on flame blowoff and CO emissions. Results show that the distribution ratios of O2, CO2 and residence time between different zones are the key factors that influence flame blowoff and CO emissions. To mitigate flame blowoff and CO emissions at part load, the distribution of O2 needs to be carefully chosen so that the primary zone operates under near-stoichiometric or slightly lean condition, while the distribution of CO2 to the primary zone also needs to be reduced. The residence time split has stronger influence on CO emissions than CO2 and O2 distribution.
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Watanabe, Hirotatsu, Santosh J. Shanbhogue und Ahmed F. Ghoniem. „Impact of Equivalence Ratio on the Macrostructure of Premixed Swirling CH4/Air and CH4/O2/CO2 Flames“. In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-43224.
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Premixed CH4/O2/CO2 flames (oxy-flames) and CH4/air flames (air-flames) were experimentally studied in a swirl-stabilized combustor. For comparing oxy and air flames, the same equivalence ratio and adiabatic flame temperature were used. CO2 dilution was adjusted to attain the same adiabatic temperature for the oxy-flame and the corresponding air-flame while keeping the equivalence ratio and Reynolds number (=20,000) the same. For high equivalence ratios, we observed flames stabilized along the inner and outer shear layers of the swirling flow and sudden expansion, respectively, in both flames. However, one notable difference between the two flames appears as the equivalence ratio reaches 0.60. At this point, the outer shear layer flame disappears in the air-flame while it persists in the oxy-flame, despite the lower burning velocity of the oxy-flame. Prior PIV measurements (Ref. 9) showed that the strains along the outer shear layer are higher than along the inner shear layer. Therefore, the extinction strain rates in both flames were calculated using a counter-flow premixed twin flame configuration. Calculations at the equivalence ratio of 0.60 show that the extinction strain rate is higher in the oxy than in the air flame, which help explain why it persists on the outer shear layer with higher strain rate. It is likely that extinction strain rates contribute to the oxy-flame stabilization when air flame extinguish in the outer shear layer. However, the trend reverses at higher equivalence ratio, and the cross point of the extinction strain rate appears at equivalence ratio of 0.64.
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Ge, Xueli, Zhongxiao Zhang, Xinglei Hu, Xiaojiang Wu und Jian Zhang. „New Correlations of Weighted Sum of Grey Gases Model Applicable to Computational Fluid Dynamics for Oxy-Fuel Combustion and Implementation“. In ASME 2017 Power Conference Joint With ICOPE-17 collocated with the ASME 2017 11th International Conference on Energy Sustainability, the ASME 2017 15th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2017 Nuclear Forum. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/power-icope2017-3171.
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Radiation heat transfer is the dominant model of heat transfer in the large scale industry boiler, especially in oxy-fuel combustion condition. Radiative properties of combustion gases and char oxidation in the oxy-fuel condition are obviously different from the air-fuel combustion, due to the N2 replaced by CO2. Through researchers proposed many helpful correlations based on the air-fuel Weighted-Sum-of-Grey-Gases-Model (WSGGM), the absorption coefficients were commonly constant or correlations were discrete by the classical molar ratio of H2O to CO2 (MR), which were mismatching the continuous value of MR in the real furnace. Meanwhile, the discrete MR is also not applied to the computational fluid dynamics (CFD). In this paper, new correlations for the WSGGM are determined as polynomial function of MR and temperature, which can be conveniently employed in Fluent by the form of user-defined-functions in C language. Parameters of model are fitted by total emittances calculated based on the timely HITEMP 2010 database. New correlations are validated by comparing the emittances with line-by-line calculations and other classical models. New correlations are employed in the CFD for the real industrial oxy-fuel combustion with the temperature range of 400–2600K, pressure path-length between 0.01 and 60 bar m. Several assumed test cases have been investigated to evaluate the accuracy of the models. Modified correlations for WSGGM give a better accuracy of the total emittances for the mixed combustion gases in the real furnace. New models including radiative and chemical reaction mechanisms have been employed to CFD modeling of combustion process for a tangentially fired 300MWe utility boiler. The industrial boiler is modeled by a partition meshing method with the hexahedral structured mesh. Due to the atmosphere shift from N2 to CO2, three aspects are essential to be modified for oxy-fuel: radiation model, char oxidation model and homogeneous volatile oxidation model. To investigate the performance of the furnace, air-fuel combustion selected as the conference, three other cases employed are defined as Oxy21 (vol21%, O2), Oxy26 (vol26, O2) and Oxy29 (vol29%, O2), respectively. Temperature profile and heat transfer are investigated for the different test cases. Meanwhile, the simulation and calculation heat transfer in the furnace are also compared. The results show the new modified simulation has an approximate 4–11% lower than the thermodynamic calculation. To achieve an identical heat flux and temperature distributions with the air-fuel case, the molar fraction 29% of O2 is essential for the selected implementation. (CSPE)
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Liu, Ruochen, Enke An und Kun Wu. „Numerical Study on Flame Mesoscopic-Characteristics of Oxy-Coal Mild Combustion“. In ASME 2016 Power Conference collocated with the ASME 2016 10th International Conference on Energy Sustainability and the ASME 2016 14th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/power2016-59006.
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For achieving efficient oxy-coal combustion in a MILD (Moderate or Intense Low Oxygen Dilution) state, the optimum operating conditions with high-velocity jets in a lab-scale cylindrical furnace (Φ200mm×2000mm) was determined. The mesoscopic characteristics of turbulent and flame behavior under different jet design and jet spacing were simulated and compared. The results show that L=30∼60mm(O2 side) and L=60mm(O2 center) conditions are recommended as oxy-coal MILD combustion as well as IFRF furnace condition, the flame front locates in distributed regime, the global regime was depict as 1 < l/lF < 4, 60 < ReT < 150 and 50 < Ka < 500 ; for flaming conditions, the flame front locates in small-scale turbulent regime or thin reaction zone, the global regime was depicted as 0.5 < l/lF < 4, 40 < ReT < 110 and 30 < Ka < 900 ; with high-velocity oxygen jet technology, the combustion process is in slow chemistry regime (Da << 1), governed by chemical-kinetic mechanism; large spacing (L=75mm) is not favored for co-flow burners due to poor radial mixing as well as the restriction of wall.
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Wiciak, Grzegorz. „ANALYSIS OF O2/N2 SEPARATION PARAMETERS ON APPLICABILITY OF MEMBRANE SYSTEM WITH GAS RECIRCULATION TO OXY-COMBUSTION PROCESSES“. In 18th International Multidisciplinary Scientific GeoConference SGEM2018. Stef92 Technology, 2018. http://dx.doi.org/10.5593/sgem2018/4.2/s19.040.
Der volle Inhalt der QuelleBerichte der Organisationen zum Thema "OX2"
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Higashide, Wendy. Bio-Oxo Technology. Office of Scientific and Technical Information (OSTI), April 2018. http://dx.doi.org/10.2172/1437008.
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Wendt, J., E. Eddings, J. Lighty, T. Ring, P. Smith, J. Thornock, W. Morris Y Jia et al. Oxy-coal Combustion Studies. Office of Scientific and Technical Information (OSTI), Januar 2012. http://dx.doi.org/10.2172/1045472.
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Gagliano, Michael, Andrew Seltzer, Hans Agarwal, Archie Robertson und Lun Wang. Oxy-Combustion Boiler Material Development. Office of Scientific and Technical Information (OSTI), Januar 2012. http://dx.doi.org/10.2172/1084024.
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Michael Gagliano, Andrew Seltzer, Hans Agarwal, Archie Robertson und Lun Wang. Oxy-Combustion Boiler Material Development. Office of Scientific and Technical Information (OSTI), Januar 2012. http://dx.doi.org/10.2172/1043821.
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Mark Schoenfield und Tom Ochs. Project Response To ASME Question for Comparison of Pure Oxy-Firing to Diluted Oxy-Firing. Office of Scientific and Technical Information (OSTI), August 2009. http://dx.doi.org/10.2172/1015453.
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Sharp, P. R. Late transition metal oxo and imido complexes. Office of Scientific and Technical Information (OSTI), Dezember 1992. http://dx.doi.org/10.2172/7017245.
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Hollis, Rebecca. Coal-Based Oxy-Fuel System Evaluation and Combustor Development; Oxy-Fuel Turbomachinery Development for Energy Intensive Industrial Applications. Office of Scientific and Technical Information (OSTI), März 2013. http://dx.doi.org/10.2172/1126866.
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Nocera, Daniel. Water Splitting by Thin Film Metal-Oxo Catalysts. Office of Scientific and Technical Information (OSTI), März 2013. http://dx.doi.org/10.2172/1360810.
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Malavasi, Massimo, und Gregory Landegger. Optimization of Pressurized Oxy-Combustion with Flameless Reactor. Office of Scientific and Technical Information (OSTI), Juni 2014. http://dx.doi.org/10.2172/1167108.
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Shah, Minish, Nich Degenstein, Monica Zanfir, Rahul Solunke, Ravi Kumar, Jennifer Bugayong und Ken Burgers. Near-Zero Emissions Oxy-Combustion Flue Gas Purification. Office of Scientific and Technical Information (OSTI), Juni 2012. http://dx.doi.org/10.2172/1054517.
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