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Sample records for benzene metabolite hydroquinone

  1. Modulation of Ras signaling alters the toxicity of hydroquinone, a benzene metabolite and component of cigarette smoke

    International Nuclear Information System (INIS)

    Benzene is an established human leukemogen, with a ubiquitous environmental presence leading to significant population exposure. In a genome-wide functional screen in the yeast Saccharomyces cerevisiae, inactivation of IRA2, a yeast ortholog of the human tumor suppressor gene NF1 (Neurofibromin), enhanced sensitivity to hydroquinone, an important benzene metabolite. Increased Ras signaling is implicated as a causal factor in the increased pre-disposition to leukemia of individuals with mutations in NF1. Growth inhibition of yeast by hydroquinone was assessed in mutant strains exhibiting varying levels of Ras activity. Subsequently, effects of hydroquinone on both genotoxicity (measured by micronucleus formation) and proliferation of WT and Nf1 null murine hematopoietic precursors were assessed. Here we show that the Ras status of both yeast and mammalian cells modulates hydroquinone toxicity, indicating potential synergy between Ras signaling and benzene toxicity. Specifically, enhanced Ras signaling increases both hydroquinone-mediated growth inhibition in yeast and genotoxicity in mammalian hematopoetic precursors as measured by an in vitro erythroid micronucleus assay. Hydroquinone also increases proliferation of CFU-GM progenitor cells in mice with Nf1 null bone marrow relative to WT, the same cell type associated with benzene-associated leukemia. Together our findings show that hydroquinone toxicity is modulated by Ras signaling. Individuals with abnormal Ras signaling could be more vulnerable to developing myeloid diseases after exposure to benzene. We note that hydroquinone is used cosmetically as a skin-bleaching agent, including by individuals with cafe-au-lait spots (which may be present in individuals with neurofibromatosis who have a mutation in NF1), which could be unadvisable given our findings

  2. The molecular mechanisms of liver and islets of Langerhans toxicity by benzene and its metabolite hydroquinone in vivo and in vitro.

    Science.gov (United States)

    Bahadar, Haji; Maqbool, Faheem; Mostafalou, Sara; Baeeri, Maryam; Gholami, Mahdi; Ghafour-Boroujerdi, Elmira; Abdollahi, Mohammad

    2015-01-01

    Benzene (C6H6) is one of the most commonly used industrial chemicals causing environmental pollution. This study aimed to examine the effect of benzene and its metabolite hydroquinone on glucose regulating organs, liver and pancreas, and to reveal the involved toxic mechanisms, in rats. In the in vivo part, benzene was dissolved in corn oil and administered through intragastric route at doses of 200, 400 and 800 mg/kg/day, for 4 weeks. And, in the in vitro part, toxic mechanisms responsible for weakening the antioxidant system in islets of Langerhans by hydroquinone at different concentrations (0.25, 0.5 and 1 mM), were revealed. Benzene exposure raised the activity of phosphoenolpyruvate carboxykinase (PEPCK), glucose 6-phosphatase (G6Pase) enzymes and increased fasting blood sugar (FBS) in comparison to control animals. Also, the activity of hepatic glucokinase (GK) was decreased significantly. Along with, a significant increase was observed in hepatic tumor necrosis factor (TNF-α) and plasma insulin in benzene treated rats. Moreover, benzene caused a significant rise in hepatic lipid peroxidation, DNA damage and oxidation of proteins. In islets of Langerhans, hydroquinone was found to decrease the capability of antioxidant system to fight free radicals. Also, the level of death proteases (caspase 3 and caspase 9) was found higher in hydroquinone exposed islets. The current study demonstrated that benzene and hydroquinone causes toxic effects on liver and pancreatic islets by causing oxidative impairment. PMID:26056850

  3. Synergistic action of the benzene metabolite hydroquinone on myelopoietic stimulating activity of granulocyte/macrophage colony-stimulating factor in vitro

    Science.gov (United States)

    Irons, R. D.; Stillman, W. S.; Colagiovanni, D. B.; Henry, V. A.; Clarkson, T. W. (Principal Investigator)

    1992-01-01

    The effects of in vitro pretreatment with benzene metabolites on colony-forming response of murine bone marrow cells stimulated with recombinant granulocyte/macrophage colony-stimulating factor (rGM-CSF) were examined. Pretreatment with hydroquinone (HQ) at concentrations ranging from picomolar to micromolar for 30 min resulted in a 1.5- to 4.6-fold enhancement in colonies formed in response to rGM-CSF that was due to an increase in granulocyte/macrophage colonies. The synergism equaled or exceeded that reported for the effects of interleukin 1, interleukin 3, or interleukin 6 with GM-CSF. Optimal enhancement was obtained with 1 microM HQ and was largely independent of the concentration of rGM-CSF. Pretreatment with other authentic benzene metabolites, phenol and catechol, and the putative metabolite trans, trans-muconaldehyde did not enhance growth factor response. Coadministration of phenol and HQ did not enhance the maximal rGM-CSF response obtained with HQ alone but shifted the optimal concentration to 100 pM. Synergism between HQ and rGM-CSF was observed with nonadherent bone marrow cells and lineage-depleted bone marrow cells, suggesting an intrinsic effect on recruitment of myeloid progenitor cells not normally responsive to rGM-CSF. Alterations in differentiation in a myeloid progenitor cell population may be of relevance in the pathogenesis of acute myelogenous leukemia secondary to drug or chemical exposure.

  4. Role of Hydroquinone-Thiol Conjugates in Benzene-Mediated Toxicity

    OpenAIRE

    Lau, Serrine S.; Kuhlman, Christopher; Bratton, Shawn B.; Monks, Terrence J.

    2009-01-01

    Hydroquinone (HQ) is a metabolite of benzene, and in combination with phenol (PHE), reproduces benzene myelotoxicity. HQ readily oxidizes to 1,4-benzoquinone (1,4-BQ) followed by the reductive addition of glutathione (GSH). Subsequent cycles of oxidation and GSH addition give rise to a variety of mono-, and multi-GSH substituted conjugates. Following administration of PHE/HQ (1.1 mmol/kg/0.9 mmol/kg, ip) to male Sprague-Dawley (SD) rats, 2-(glutathion-S-yl)HQ [GS-HQ], 2,5-bis-(glutathion-S-yl...

  5. Modulation of mast cell and basophil functions by benzene metabolites.

    Science.gov (United States)

    Triggiani, Massimo; Loffredo, Stefania; Granata, Francescopaolo; Staiano, Rosaria I; Marone, Gianni

    2011-11-01

    Benzene is a carcinogenic compound used in industrial manufacturing and a common environmental pollutant mostly derived from vehicle emissions and cigarette smoke. Benzene exposure is associated with a variety of clinical conditions ranging from hematologic diseases to chronic lung disorders. Beside its direct toxicity, benzene exerts multiple effects after being converted to reactive metabolites such as hydroquinone and benzoquinone. Mast cells and basophils are primary effector cells involved in the development of respiratory allergies such as rhinitis and bronchial asthma and they play an important role in innate immunity. Benzene and its metabolites can influence mast cell and basophil responses either directly or by interfering with other cells, such as T cells, macrophages and monocytes, which are functionally connected to mast cells and basophils. Hydroquinone and benzoquinone inhibit the release of preformed mediators, leukotriene synthesis and cytokine production in human basophils stimulated by IgE- and non IgE-mediated agonists. Furthermore, these metabolites reduce IgE-mediated degranulation of mast cells and the development of allergic lung inflammation in rats. Both in vitro and in vivo studies indicate that benzene metabolites alter biochemical and functional activities of other immunocompetent cells and may impair immune responses in the lung. These inhibitory effects of benzene metabolites are primarily mediated by interference with early transduction signals such as PI3 kinase. Together, currently available studies indicate that benzene metabolites interfere by multiple mechanisms with the role of basophils and mast cells in innate immunity and in chronic inflammation in the lung. PMID:22103854

  6. Peroxidase-dependent metabolism of benzene's phenolic metabolites and its potential role in benzene toxicity and carcinogenicity.

    OpenAIRE

    Smith, M T; Yager, J W; Steinmetz, K L; Eastmond, D A

    1989-01-01

    The metabolism of two of benzene's phenolic metabolites, phenol and hydroquinone, by peroxidase enzymes has been studied in detail. Studies employing horseradish peroxidase and human myeloperoxidase have shown that in the presence of hydrogen peroxide phenol is converted to 4,4'-diphenoquinone and other covalent binding metabolites, whereas hydroquinone is converted solely to 1,4-benzoquinone. Surprisingly, phenol stimulates the latter conversion rather than inhibiting it, an effect that may ...

  7. Formation of reactive metabolites from benzene

    International Nuclear Information System (INIS)

    Rat liver mitoplasts were incubated first with [3H]dGTP, to form DNA labeled in G, and then with [14C]benzene. The DNA was isolated and upon isopycnic density gradient centrifugation in CsCl yielded a single fraction of DNA labeled with both [3H] and [14C]. These data are consistent with the covalent binding of one or more metabolites of benzene to DNA. The DNA was enzymatically hydrolyzed to deoxynucleosides and chromatographed to reveal at least seven deoxyguanosine adducts. Further studies with labeled deoxyadenine revealed one adduct on deoxyadenine. [3H]Deoxyguanosine was reacted with [14C]hydroquinone or benzoquinone. The product was characterized using uv, fluorescence, mass and NMR spectroscopy. A proposed structure is described. (orig.)

  8. The role of natural chlorinated hydroquinone metabolites in ligninolytic fungi

    NARCIS (Netherlands)

    Teunissen, P.J.M.

    1999-01-01

    Ligninolytic Basidiomycetes have been reported to produce a wide variety of chloroaromatic compounds as secondary metabolites, which are structurally similar to environmental pollutants. Among these are chlorinated hydroquinone metabolites (CHM), such as 2-chloro-1,4-dimethoxybenzene (2Cl-14DMB), 2,

  9. Exposure to benzene metabolites causes oxidative damage in Saccharomyces cerevisiae.

    Science.gov (United States)

    Raj, Abhishek; Nachiappan, Vasanthi

    2016-06-01

    Hydroquinone (HQ) and benzoquinone (BQ) are known benzene metabolites that form reactive intermediates such as reactive oxygen species (ROS). This study attempts to understand the effect of benzene metabolites (HQ and BQ) on the antioxidant status, cell morphology, ROS levels and lipid alterations in the yeast Saccharomyces cerevisiae. There was a reduction in the growth pattern of wild-type cells exposed to HQ/BQ. Exposure of yeast cells to benzene metabolites increased the activity of the anti-oxidant enzymes catalase, superoxide dismutase and glutathione peroxidase but lead to a decrease in ascorbic acid and reduced glutathione. Increased triglyceride level and decreased phospholipid levels were observed with exposure to HQ and BQ. These results suggest that the enzymatic antioxidants were increased and are involved in the protection against macromolecular damage during oxidative stress; presumptively, these enzymes are essential for scavenging the pro-oxidant effects of benzene metabolites. PMID:27016252

  10. The role of natural chlorinated hydroquinone metabolites in ligninolytic fungi

    OpenAIRE

    Teunissen, P.J.M.

    1999-01-01

    Ligninolytic Basidiomycetes have been reported to produce a wide variety of chloroaromatic compounds as secondary metabolites, which are structurally similar to environmental pollutants. Among these are chlorinated hydroquinone metabolites (CHM), such as 2-chloro-1,4-dimethoxybenzene (2Cl-14DMB), 2,6-dichloro-1,4-dimethoxybenzene (26DCl-14DMB), tetrachloro-1,4-dimethoxybenzene and tetrachloro-4-methoxyphenol, which are synthesized by 11 genera of Basidiomycetes.The biosynthesis of these chlor...

  11. Quinone and Hydroquinone Metabolites from the Ascidians of the Genus Aplidium

    OpenAIRE

    Camila Spereta Bertanha; Ana Helena Januário; Tavane Aparecida Alvarenga; Letícia Pereira Pimenta; Silva, Márcio Luis Andrade e; Wilson Roberto Cunha; Patrícia Mendonça Pauletti

    2014-01-01

    Ascidians of the genus Aplidium are recognized as an important source of chemical diversity and bioactive natural products. Among the compounds produced by this genus are non-nitrogenous metabolites, mainly prenylated quinones and hydroquinones. This review discusses the isolation, structural elucidation, and biological activities of quinones, hydroquinones, rossinones, longithorones, longithorols, floresolides, scabellones, conicaquinones, aplidinones, thiaplidiaquinones, and conithiaquinone...

  12. Quinone and Hydroquinone Metabolites from the Ascidians of the Genus Aplidium

    Directory of Open Access Journals (Sweden)

    Camila Spereta Bertanha

    2014-06-01

    Full Text Available Ascidians of the genus Aplidium are recognized as an important source of chemical diversity and bioactive natural products. Among the compounds produced by this genus are non-nitrogenous metabolites, mainly prenylated quinones and hydroquinones. This review discusses the isolation, structural elucidation, and biological activities of quinones, hydroquinones, rossinones, longithorones, longithorols, floresolides, scabellones, conicaquinones, aplidinones, thiaplidiaquinones, and conithiaquinones. A compilation of the 13C-NMR spectral data of these compounds is also presented.

  13. Quinone and hydroquinone metabolites from the ascidians of the genus Aplidium.

    Science.gov (United States)

    Bertanha, Camila Spereta; Januário, Ana Helena; Alvarenga, Tavane Aparecida; Pimenta, Letícia Pereira; Silva, Márcio Luis Andrade E; Cunha, Wilson Roberto; Pauletti, Patrícia Mendonça

    2014-06-01

    Ascidians of the genus Aplidium are recognized as an important source of chemical diversity and bioactive natural products. Among the compounds produced by this genus are non-nitrogenous metabolites, mainly prenylated quinones and hydroquinones. This review discusses the isolation, structural elucidation, and biological activities of quinones, hydroquinones, rossinones, longithorones, longithorols, floresolides, scabellones, conicaquinones, aplidinones, thiaplidiaquinones, and conithiaquinones. A compilation of the 13C-NMR spectral data of these compounds is also presented. PMID:24927227

  14. Cytochromes P450 in benzene metabolism and involvement of their metabolites and reactive oxygen species in toxicity.

    OpenAIRE

    I. Gut; Nedelcheva, V; Soucek, P; Stopka, P.; Tichavská, B

    1996-01-01

    Cytochrome P450 (CYP) 2E1 was the most efficient CYP enzyme that oxidized benzene to soluble and covalently bound metabolites in rat and human liver microsomes. The covalent binding was due mostly to the formation of benzoquinone (BQ), the oxidation product of hydroquinone (HQ), and was inversely related to the formation of soluble metabolites. In rats, inhalation of benzene (4 mg/liter of air) caused a rapid destruction of CYP2B1 previously induced by phenobarbital. The ability of benzene me...

  15. Genome-wide functional profiling reveals genes required for tolerance to benzene metabolites in yeast.

    Directory of Open Access Journals (Sweden)

    Matthew North

    Full Text Available Benzene is a ubiquitous environmental contaminant and is widely used in industry. Exposure to benzene causes a number of serious health problems, including blood disorders and leukemia. Benzene undergoes complex metabolism in humans, making mechanistic determination of benzene toxicity difficult. We used a functional genomics approach to identify the genes that modulate the cellular toxicity of three of the phenolic metabolites of benzene, hydroquinone (HQ, catechol (CAT and 1,2,4-benzenetriol (BT, in the model eukaryote Saccharomyces cerevisiae. Benzene metabolites generate oxidative and cytoskeletal stress, and tolerance requires correct regulation of iron homeostasis and the vacuolar ATPase. We have identified a conserved bZIP transcription factor, Yap3p, as important for a HQ-specific response pathway, as well as two genes that encode putative NAD(PH:quinone oxidoreductases, PST2 and YCP4. Many of the yeast genes identified have human orthologs that may modulate human benzene toxicity in a similar manner and could play a role in benzene exposure-related disease.

  16. Inhibitory effect of benzene metabolites on nuclear DNA synthesis in bone marrow cells

    International Nuclear Information System (INIS)

    Effects of endogenously produced and exogenously added benzene metabolites on the nuclear DNA synthetic activity were investigated using a culture system of mouse bone marrow cells. Effects of the metabolites were evaluated by a 30-min incorporation of [3H]thymidine into DNA following a 30-min interaction with the cells in McCoy's 5a medium with 10% fetal calf serum. Phenol and muconic acid did not inhibit nuclear DNA synthesis. However, catechol, 1,2,4-benzenetriol, hydroquinone, and p-benzoquinone were able to inhibit 52, 64, 79, and 98% of the nuclear DNA synthetic activity, respectively, at 24 μM. In a cell-free DNA synthetic system, catechol and hydroquinone did not inhibit the incorporation of [3H]thymidine triphosphate into DNA up to 24 μM but 1,2,4-benzenetriol and p-benzoquinone did. The effect of the latter two benzene metabolites was completely blocked in the presence of 1,4-dithiothreitol (1 mM) in the cell-free assay system. Furthermore, when DNA polymerase α, which requires a sulfhydryl (SH) group as an active site, was replaced by DNA polymerase 1, which does not require an SH group for its catalytic activity, p-benzoquinone and 1,2,4-benzenetriol were unable to inhibit DNA synthesis. Thus, the data imply the p-benzoquinone and 1,2,4-benzenetriol inhibited DNA polymerase α, consequently resulting in inhibition of DNA synthesis in both cellular and cell-free DNA synthetic systems. The present study identifies catechol, hydroquinone, p-benzoquinone, and 1,2,4-benzenetriol as toxic benzene metabolites in bone marrow cells and also suggests that their inhibitory action on DNA synthesis is mediated by mechanism(s) other than that involving DNA damage as a primary cause

  17. Metabolites of benzene are potent inhibitors of gap-junction intercellular communication

    Energy Technology Data Exchange (ETDEWEB)

    Rivedal, Edgar [Norwegian Radium Hospital, Institute for Cancer Research, Montebello, Oslo (Norway); Witz, Gisela [Robert Wood Johnson Medical School/UMDNJ, Environmental and Occupational Health Sciences Institute and Department of Environmental and Occupational Medicine, Piscataway, New Jersey (United States)

    2005-06-01

    Chronic exposure to benzene has been shown to lead to bone marrow depression and the development of leukemia. The mechanism underlying the carcinogenicity of benzene is unknown, although a number of genetic changes including chromosomal aberrations have been associated with benzene toxicity. Metabolism of benzene is required for the induced toxicological effects. We have investigated the effect of trans,trans-muconaldehyde (MUC), hydroquinone (HQ), and four MUC metabolites on gap-junction intercellular communication (GJIC). Inhibition of GJIC has been considered a possible predictor of tumor promoters and non-genotoxic carcinogens, and shown to result in perturbation of hematopoiesis. MUC was found to be a strong inhibitor of GJIC (EC50=12 {mu}mol L{sup -1}) in rat liver epithelial cells IAR20, with potency similar to that of chlordane (EC50=7 {mu}mol L{sup -1}). HQ inhibited GJIC with an EC50 of 25 {mu}mol L{sup -1}, and the metabolite OH/CHO with an EC50 of 58 {mu}mol L{sup -1}. The other MUC metabolites tested, CHO/COOH and OH/COOH were weak inhibitors of GJIC whereas COOH/COOH had no effect. Benzene itself had no effect on GJIC when tested in concentrations up to 20 mmol L{sup -1}. The relative potency observed for the metabolites on GJIC is similar to their hematotoxic effects. The effect of MUC on GJIC was observed to take place concordant with a dramatic loss of connexin 43 (Cx43) from the cells as visualized by Western blotting. Substances with the ability to inhibit Cx43-dependent GJIC have previously been observed to interfere with normal hematopoietic development. The ability of benzene metabolites to interfere with gap-junction functionality, and especially the dramatic loss of Cx43 induced by MUC, should therefore be considered as a possible mechanism for benzene-induced hematotoxicity and development of leukemia. (orig.)

  18. Human CYP2E1-dependent and human sulfotransferase 1A1-modulated induction of micronuclei by benzene and its hydroxylated metabolites in Chinese hamster V79-derived cells.

    Science.gov (United States)

    Jiang, Hao; Lai, Yanmei; Hu, Keqi; Wei, Qinzhi; Liu, Yungang

    2014-12-01

    Benzene is a ubiquitous environmental pollutant and a confirmed human carcinogen, which requires metabolic activation, primarily by CYP2E1, for most of its biological actions. Chromosome damages in benzene-exposed workers and rodents have been observed, and in their urine sulfo- and glucuronide-conjugates of phenol and hydroquinone were present. Yet, direct evidence for human CYP2E1-activated mutagenicity of benzene and the exact significance of phase II metabolism for inactivating benzene metabolites are still missing. In the present study, benzene and its oxidized metabolites (phenol, hydroquinone, catechol, 1,2,4-trihydroxybenzene and 1,4-benzoquinone) were investigated for induction of micronuclei in a V79-derived cell line genetically engineered for expression of both human CYP2E1 and human sulfotransferase (SULT) 1A1 (indicated by active micronuclei induction by 1-hydroxymethylpyrene). The results demonstrated concentration-dependent induction of micronuclei by benzene and phenol, though with lower potency or efficacy than the other metabolites. Inhibition of CYP2E1 by 1-aminobenzotriazole did not change the effect of benzoquinone, but completely abolished that of benzene and phenol, and attenuated that of the other compounds. Moreover, inhibition of SULT1A1 by pentachlorophenol potentiated the effects of benzene, hydroquinone, catechol and trihydroxybenzene. Ascorbic acid, a reducing and free radical-scavenging agent, significantly lowered the effects of hydroquinone, catechol, trihydroxybenzene as well as N-nitrosodimethylamine (a known CYP2E1-dependent promutagen), with that of benzoquinone unaffected. These results suggest that in addition to activating benzene and phenol, human CYP2E1 may further convert hydroquinone, catechol and trihydroxybenzene to more genotoxic metabolites, and sulfo-conjugation of the multi-hydroxylated metabolites of benzene by human SULT1A1 may represent an important detoxifying pathway. PMID:25771868

  19. Phase II metabolism of benzene.

    OpenAIRE

    Schrenk, D.; Orzechowski, A.; Schwarz, L R; Snyder, R.; Burchell, B; Ingelman-Sundberg, M; K. W. DE BOCK

    1996-01-01

    The hepatic metabolism of benzene is thought to be a prerequisite for its bony marrow toxicity. However, the complete pattern of benzene metabolites formed in the liver and their role in bone marrow toxicity are not fully understood. Therefore, benzene metabolism was studied in isolated rodent hepatocytes. Rat hepatocytes released benzene-1,2-dihydrodiol, hydroquinone (HQ), catechol (CT), phenol (PH), trans-trans-muconic acid, and a number of phase II metabolites such as PH sulfate and PH glu...

  20. Benzene metabolite levels in blood and bone marrow of B6C3F{sub 1} mice after low-level exposure

    Energy Technology Data Exchange (ETDEWEB)

    Bechtold, W.E.; Strunk, M.R.; Thornton-Manning, J.R. [and others

    1995-12-01

    Studies at the Inhalation Toxicology Research Institute (ITRI) have explored the species-specific uptake and metabolism of benzene. Results have shown that metabolism is dependent on both dose and route of administration. Of particular interest were shifts in the major metabolic pathways as a function of exposure concentration. In these studies, B6C3F{sub 1} mice were exposed to increasing levels of benzene by either gavage or inhalation. As benzene internal dose increased, the relative amounts of muconic acid and hydroquinone decreased. In contrast, the relative amount of catechol increased with increasing exposure. These results show that the relative levels of toxic metabolites are a function of exposure level. Based on these results and assuming a linear relationship between exposure concentration and levels of bone marrow metabolites, it would be difficult to detect an elevation of any phenolic metabolites above background after occupational exposures to the OSHA Permissible Exposure Limit of 1 ppm benzene.

  1. Species differences in the metabolism of benzene

    Energy Technology Data Exchange (ETDEWEB)

    Henderson, R.F. [Inhalation Toxicology Research Institute, Albuquerque, NM (United States)

    1996-12-01

    The pathways of metabolism of benzene appear to be qualitatively similar in all species studied thus far. However, there are quantitative differences in the fraction of benzene metabolized by the different pathways. These species differences become important for risk assessments based on animal data. Mice have a greater overall capacity to metabolize benzene than rats or primates, based on mass balance studies conducted in vivo using radiolabled benzene. Mice and monkeys metabolize more of the benzene to hydroquinone metabolites than do rats or chimpanzees, especially at low doses. Nonhuman primates metabolize less of the benzene to muconic acid than do rodents or humans. In all species studied, a greater proportion of benzene is converted to hydroquinone and ring-breakage metabolites at low doses than at high doses. This finding should be considered in attempting to extrapolate the toxicity of benzene observed at high doses to predicted toxicity at low doses. Because ring-breakage metabolites and hydroquinone have both been implicated in the toxicity of benzene, the higher formation of those metabolites in the mouse may partially explain why mice are more sensitive to benzene than are rats. Metabolism of benzene in humans, the species of interest, does not exactly mimic that of any animal species studied. More information on the urinary and blood metabolites of occupationally exposed people is required to determine the fractional conversion of benzene to putative toxic metabolites and the degree of variability present in human subjects. 12 refs., 4 tabs.

  2. Phenol-induced stimulation of hydroquinone bioactivation in mouse bone marrow in vivo: Possible implications in benzene myelotoxicity

    International Nuclear Information System (INIS)

    The coadministration of phenol (PH) and hydroquinone (HQ) has been shown to produce myelotoxicity in mice similar to that observed following benzene exposure. One explanation of this phenomenon may be that PH enhances the peroxidase-dependent metabolic activation of HQ in the mouse bone marrow (BM). Here we report that 14C-HQ and 14C-PH bind covalently to tissue proteins of blood, BM, liver and kidney, when administered ip to the mouse in vivo. Phenol, when coadministered with 14C-Hq, significantly stimulated the covalent binding of 14C-HQ oxidation products to blood and BM proteins but had no significant effect on covalent binding of 14C-HQ oxidation products to liver and kidney proteins. When HQ was coadministered with 14C-PH, covalent binding of 14C-PH oxidation products to BM, kidney and blood proteins, was stimulated, whereas covalent binding in the liver was significantly inhibited. These results suggest that increased delivery to extrahepatic tissues is responsible for the enhanced covalent binding of HQ or PH to tissue proteins following their coadministration in vivo. They do not, however, rule out a secondary role for the PH-induced stimulation of peroxidase-mediated HQ metabolism in benzene myelotoxicity

  3. Mechanistic considerations in benzene physiological model development

    Energy Technology Data Exchange (ETDEWEB)

    Medinsky, M.A.; Kenyon, E.M.; Seaton, M.J.; Schlosser, P.M. [Chemical Industry Institute of Toxicology, Research Triangle Park, NC (United States)

    1996-12-01

    Benzene, an important industrial solvent, is also present in unleaded gasoline and cigarette smoke. The hematotoxic effects of benzene in humans are well documented and include aplastic anemia, pancytopenia, and acute myelogenous leukemia. However, the risks of leukemia at low exposure concentrations have not been established. A combination of metabolites (hydroquinone and phenol, for example) may be necessary to duplicate the hematotoxic effect of benzene, perhaps due in part to the synergistic effect of phenol on myeloperoxidase-mediated oxidation of hydroquinone to the reactive metabolite benzoquinone. Because benzene and its hydroxylated metabolites (phenol, hydroquinone, and catechol) are substrates for the same cytochrome P450 enzymes, competitive interactions among the metabolites are possible. In vivo data on metabolite formation by mice exposed to various benzene concentrations are consistent with competitive inhibition of phenol oxidation by benzene. In vitro studies of the metabolic oxidation of benzene, phenol, and hydroquinone are consistent with the mechanism of competitive interaction among the metabolites. The dosimetry of benzene and its metabolites in the target tissue, bone marrow, depends on the balance of activation processes such as enzymatic oxidation and deactivation processes such as conjugation and excretion. Phenol, the primary benzene metabolite, can undergo both oxidation and conjugation. Thus the potential exists for competition among various enzymes for phenol. Zonal localization of phase I and phase 11 enzymes in various regions of the liver acinus also impacts this competition. Biologically based dosimetry models that incorporate the important determinants of benzene flux, including interactions with other chemicals, will enable prediction of target tissue doses of benzene and metabolites at low exposure concentrations relevant for humans. 39 refs., 4 figs., 2 tabs.

  4. Metabolism of phenol and hydroquinone to reactive products by macrophage peroxidase or purified prostaglandin H synthase

    International Nuclear Information System (INIS)

    Macrophages, an important cell-type of the bone marrow stroma, are possible targets of benzene toxicity because they contain relatively large amounts of prostaglandin H synthase (PHS), which is capable of metabolizing phenolic compounds to reactive species. PHS also catalyzes the production of prostaglandins, negative regulators of myelopoiesis. Studies indicate that the phenolic metabolites of benzene are oxidized in bone marrow to reactive products via peroxidases. With respect to macrophages, PHS peroxidase is implicated, as in vivo benzene-induced myelotoxicity is prevented by low doses of nonsteroidal anti-inflammatory agents, drugs that inhibit PHS. Incubations of either 14C-phenol or 14C-hydroquinone with a lysate of macrophages collected from mouse peritoneum (greater than 95% macrophages), resulted in an irreversible binding to protein that was dependent upon H2O2, incubation time, and concentration of radiolabel. Production of protein-bound metabolites from phenol or hydroquinone was inhibited by the peroxidase inhibitor aminotriazole. Protein binding from 14C-phenol also was inhibited by 8 microM hydroquinone, whereas binding from 14C-hydroquinone was stimulated by 5 mM phenol. The nucleophile cysteine inhibited protein binding of both phenol and hydroquinone and increased the formation of radiolabeled water-soluble metabolites. Similar to the macrophage lysate, purified PHS also catalyzed the conversion of phenol to metabolites that bound to protein and DNA; this activation was both H2O2- and arachidonic acid-dependent. These results indicate a role for macrophage peroxidase, possibly PHS peroxidase, in the conversion of phenol and hydroquinone to reactive metabolites and suggest that the macrophage should be considered when assessing the hematopoietic toxicity of benzene

  5. Critical issues in benzene toxicity and metabolism: The effect of interactions with other organic chemicals on risk assessment

    Energy Technology Data Exchange (ETDEWEB)

    Medinsky, M.A.; Schlosser, P.M.; Bond, J.A. [Chemical Industry Institute of Toxicology, Research Triangle Park, NC (United States)

    1994-11-01

    Benzene, an important industrial solvent, is also present in unleaded gasoline and cigarette smoke. The hematotoxic effects of benzene are well documented and include aplastic anemia and pancytopenia. Some individuals exposed repeatedly to cytotoxic concentrations of benzene develop acute myeloblastic anemia. It has been hypothesized that metabolism of benzene is required for its toxicity, although administration of no single benzene metabolite duplicates the toxicity of benzene. Several investigators have demonstrated that a combination of metabolites (hydroquinone and phenol, for example) is necessary to duplicate the hematotoxic effect of benzene. Enzymes implicated in the metabolic activation of benzene and its metabolites include the cytochrome P450 monooxygenases and myeloperoxidase. Since benzene and its hydroxylated metabolites (phenol, hydroquinone, and catechol) are substrates for the same cytochrome P450 enzymes, competitive interactions among the metabolites are possible. In vivo data on metabolite formation by mice exposed to various benzene concentrations are consistent with competitive inhibition of phenol oxidation by benzene. Other organic molecules that are substrates for cytochrome P450 can inhibit the metabolism of benzene. For example, toluene has been shown to inhibit the oxidation of benzene in a noncompetitive manner. Enzyme inducers, such as ethanol, can alter the target tissue dosimetry of benzene metabolites by inducing enzymes responsible for oxidation reactions involved in benzene metabolism. 24 refs., 6 figs., 2 tabs.

  6. Albumin Adducts of Electrophilic Benzene Metabolites in Benzene-Exposed and Control Workers

    OpenAIRE

    Lin, Yu-Sheng; Vermeulen, Roel; Tsai, Chin H.; Waidyanatha, Suramya; Lan, Qing; Rothman, Nathaniel; Smith, Martyn T.; Zhang, Luoping; Shen, Min; Li, Guilan; Yin, Songnian; Kim, Sungkyoon; Rappaport, Stephen M.

    2006-01-01

    Background Metabolism of benzene produces reactive electrophiles, including benzene oxide (BO), 1,4-benzoquinone (1,4-BQ), and 1,2-benzoquinone (1,2-BQ), that are capable of reacting with blood proteins to produce adducts. Objectives The main purpose of this study was to characterize relationships between levels of albumin adducts of these electrophiles in blood and the corresponding benzene exposures in benzene-exposed and control workers, after adjusting for important covariates. Because se...

  7. Reverse isotope dilution method for determining benzene and metabolites in tissues

    Energy Technology Data Exchange (ETDEWEB)

    Bechtold, W.E.; Sabourin, P.J.; Henderson, R.F.

    1988-07-01

    A method utilizing reverse isotope dilution for the analysis of benzene and its organic soluble metabolites in tissues of rats and mice is presented. Tissues from rats and mice that had been exposed to radiolabeled benzene were extracted with ethyl acetate containing known, excess quantities of unlabeled benzene and metabolites. Butylated hydroxytoluene was added as an antioxidant. The ethyl acetate extracts were analyzed with semipreparative reversed-phase HPLC. Isolated peaks were collected and analyzed for radioactivity (by liquid scintillation spectrometry) and for mass (by UV absorption). The total amount of each compound present was calculated from the mass dilution of the radiolabeled isotope. This method has the advantages of high sensitivity, because of the high specific activity of benzene, and relative stability of the analyses, because of the addition of large amounts of unlabeled carrier analogue.

  8. Human urine certified reference material CZ 6010: creatinine and toluene metabolites (hippuric acid and o-cresol) and a benzene metabolite (phenol)

    Czech Academy of Sciences Publication Activity Database

    Šperlingová, I.; Dabrowská, L.; Stránský, V.; Kučera, Jan; Tichý, M.

    2007-01-01

    Roč. 387, č. 7 (2007), s. 2419-2424. ISSN 1618-2642 Institutional research plan: CEZ:AV0Z10480505 Keywords : toluene metabolites * benzene metabolite * human urine Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 2.867, year: 2007

  9. The effect of dose, dose rate, route of administration, and species on tissue and blood levels of benzene metabolites.

    OpenAIRE

    Henderson, R F; Sabourin, P J; Bechtold, W E; Griffith, W. C.; Medinsky, M A; Birnbaum, L S; Lucier, G W

    1989-01-01

    Studies were completed in F344/N rats and B6C3F1 mice to determine the effect of dose, dose rate, route of administration, and rodent species on formation of total and individual benzene metabolites. Oral doses of 50 mg/kg or higher saturated the capacity for benzene metabolism in both rats and mice, resulting in an increased proportion of the administered dose being exhaled as benzene. The saturating air concentration for benzene metabolism during 6-hr exposures was between 130 and 900 ppm. ...

  10. Hydroquinone induces DNA hypomethylation-independent overexpression of retroelements in human leukemia and hematopoietic stem cells.

    Science.gov (United States)

    Conti, Anastasia; Rota, Federica; Ragni, Enrico; Favero, Chiara; Motta, Valeria; Lazzari, Lorenza; Bollati, Valentina; Fustinoni, Silvia; Dieci, Giorgio

    2016-06-10

    Hydroquinone (HQ) is an important benzene-derived metabolite associated with acute myelogenous leukemia risk. Although altered DNA methylation has been reported in both benzene-exposed human subjects and HQ-exposed cultured cells, the inventory of benzene metabolite effects on the epigenome is only starting to be established. In this study, we used a monocytic leukemia cell line (THP-1) and hematopoietic stem cells (HSCs) from cord blood to investigate the effects of HQ treatment on the expression of the three most important families of retrotransposons in the human genome: LINE-1, Alu and Endogenous retroviruses (HERVs), that are normally subjected to tight epigenetic silencing. We found a clear tendency towards increased retrotransposon expression in response to HQ exposure, more pronounced in the case of LINE-1 and HERV. Such a partial loss of silencing, however, was generally not associated with HQ-induced DNA hypomethylation. On the other hand, retroelement derepression was also observed in the same cells in response to the hypomethylating agent decitabine. These observations suggest the existence of different types of epigenetic switches operating at human retroelements, and point to retroelement activation in response to benzene-derived metabolites as a novel factor deserving attention in benzene carcinogenesis studies. PMID:27154225

  11. Interphase cytogenetics of workers exposed to benzene

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, L.; Wang, Yunxia; Venkatesh, P. [Univ. of California, Berkeley, CA (United States)] [and others

    1996-12-01

    Fluorescence in situ hybridization (FISH) is a powerful new technique that allows numerical chromosome aberrations (aneuploidy) to be detected in interphase cells. In previous studies, FISH has been used to demonstrate that the benzene metabolites hydroquinone and 1,2,4-benzenetriol induce aneuploidy of chromosomes 7 and 9 in cultures of human cells. In the present study, we used an interphase FISH procedure to perform cytogenetic analyses on the blood cells of 43 workers exposed to benzene (median=31 ppm, 8-hr time-weighted average) and 44 matched controls from Shanghai, China. High benzene exposure (>31 ppm, n=22) increased the hyperdiploid frequency of chromosome 9 (p<0.01), but lower exposure (<31 ppm, n=21) did not. Trisomy 9 was the major form of benzene-induced hyperdiploidy. The level of hyperdiploidy in exposed workers correlated with their urinary phenol level (r= 0.58, p < 0.0001), a measure of internal benzene close. A significant correlation was also found between hyperdiploicly and decreased absolute lymphocyte count, an indicator of benzene hematotoxicity, in the exposed group (r=-0.44, p=0.003) but not in controls (r=-0.09, P=0.58). These results show that high benzene exposure induces aneuploidy of chromosome 9 in nondiseased individuals, with trisomy being the most prevalent form. They further highlight the usefulness of interphase cytogenetics and FISH for the rapid and sensitive detection of aneuploidy in exposed human populations. 35 refs., 3 figs., 2 tabs.

  12. Preliminary study to prepare a reference material of toluene metabolite - o-cresol and benzene metabolite-phenol - in human

    Czech Academy of Sciences Publication Activity Database

    Šperlingová, I.; Dabrowská, L.; Stránský, V.; Kučera, Jan; Tichý, M.

    2006-01-01

    Roč. 11, č. 5 (2006), s. 231-235. ISSN 0949-1775 R&D Projects: GA MZd NR7831 Institutional research plan: CEZ:AV0Z10480505 Keywords : reference material * toluene metabolites * o-cresol Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 0.640, year: 2006

  13. Metabolism of benzene and phenol by a reconstituted purified phenobarbital induced rat liver mixed function oxidase system

    International Nuclear Information System (INIS)

    Cytochrome P-450 and the electron-donor, NADPH-cytochrome c reductase were isolated from phenobarbital induced rat liver microsomes. Both benzene and its primary metabolite phenol, were substrates for the reconstituted purified phenobarbital induced rat liver mixed function oxidase system. Benzene was metabolized to phenol and the polyhydroxylated metabolites; catechol, hydroquinone and 1,2,4 benzenetriol. Benzene elicited a Type I spectral change upon its interaction with the cytochrome P-450 while phenol's interaction with the cytochrome P-450 produced a reverse Type I spectra. The formation of phenol showed a pH optimum of 7.0 compared with 6.6-6.8 for the production of the polyhyrdoxylated metabolites. Cytochrome P-450 inhibitors, such as metyrapone and SKF 525A, diminished the production of phenol from benzene but not the production of the polyhydroxylated metabolites from phenol. The radical trapping agents, DMSO, KTBA and mannitol, decreased the recovery of polyhydroxylated metabolites, from 14C-labeled benzene and/or phenol. As KTBA and DMSO interacted with OH. There was a concomitant release of ethylene and methane, which was measured. Desferrioxamine, an iron-chelator and catalase also depressed the recovery of polyhydroxylated metabolites. In summary, benzene and phenol were both substrates for this reconstituted purified enzyme system, but they differed in binding to cytochrome P-450, pH optima and mode of hydroxylation

  14. Metabolism of benzene and phenol by a reconstituted purified phenobarbital induced rat liver mixed function oxidase system

    Energy Technology Data Exchange (ETDEWEB)

    Griffiths, J.C.

    1986-01-01

    Cytochrome P-450 and the electron-donor, NADPH-cytochrome c reductase were isolated from phenobarbital induced rat liver microsomes. Both benzene and its primary metabolite phenol, were substrates for the reconstituted purified phenobarbital induced rat liver mixed function oxidase system. Benzene was metabolized to phenol and the polyhydroxylated metabolites; catechol, hydroquinone and 1,2,4 benzenetriol. Benzene elicited a Type I spectral change upon its interaction with the cytochrome P-450 while phenol's interaction with the cytochrome P-450 produced a reverse Type I spectra. The formation of phenol showed a pH optimum of 7.0 compared with 6.6-6.8 for the production of the polyhyrdoxylated metabolites. Cytochrome P-450 inhibitors, such as metyrapone and SKF 525A, diminished the production of phenol from benzene but not the production of the polyhydroxylated metabolites from phenol. The radical trapping agents, DMSO, KTBA and mannitol, decreased the recovery of polyhydroxylated metabolites, from /sup 14/C-labeled benzene and/or phenol. As KTBA and DMSO interacted with OH. There was a concomitant release of ethylene and methane, which was measured. Desferrioxamine, an iron-chelator and catalase also depressed the recovery of polyhydroxylated metabolites. In summary, benzene and phenol were both substrates for this reconstituted purified enzyme system, but they differed in binding to cytochrome P-450, pH optima and mode of hydroxylation.

  15. Intracellular mechanisms of hydroquinone toxicity on endotoxin-activated neutrophils.

    Science.gov (United States)

    Hebeda, Cristina Bichels; Pinedo, Fernanda Júdice; Bolonheis, Simone Marques; Ferreira, Zulma F; Muscará, Marcelo Nicolas; Teixeira, Simone Aparecida; Farsky, Sandra Helena Poliselli

    2012-11-01

    Circulating neutrophils promptly react to different substances in the blood and orchestrate the beginning of the innate inflammatory response. We have shown that in vivo exposure to hydroquinone (HQ), the most oxidative compound of cigarette smoke and a toxic benzene metabolite, affects circulating neutrophils, making them unresponsive to a subsequent bacterial infection. In order to understand the action of toxic molecular mechanisms on neutrophil functions, in vitro HQ actions on pro-inflammatory mediator secretions evoked by Escherichia coli lipopolysaccharide (LPS) were investigated. Neutrophils from male Wistar rats were cultured with vehicle or HQ (5 or 10 μM; 2 h) and subsequently incubated with LPS (5 μg/ml; 18 h). Hydroquinone treatment impaired LPS-induced nitric oxide (NO), tumour necrosis factor α (TNF-α), interleukin (IL)-1β and IL-6 secretions by neutrophils. The toxic effect was not dependent on cell death, reduced expression of the LPS receptor or toll-like receptor-4 (TLR-4) or cell priming, as HQ did not induce reactive oxygen species generation or β(2)integrin membrane expression. The action of toxic mechanisms on cytokine secretion was dependent on reduced gene synthesis, which may be due to decreased nuclear factor κB (NF-κB) nuclear translocation. Conversely, this intracellular pathway was not involved in impaired NO production because HQ treatments only affected inducible nitric oxide synthase protein expression and activity, suggesting posttranscriptional and/or posttranslational mechanisms of action. Altogether, our data show that HQ alters the action of different LPS-activated pathways on neutrophils, which may contribute to the impaired triggering of the host innate immune reaction detected during in vivo HQ exposure. PMID:22717997

  16. Benzene metabolism by human liver microsomes in relation to cytochrome P450 2E1 activity.

    Science.gov (United States)

    Seaton, M J; Schlosser, P M; Bond, J A; Medinsky, M A

    1994-09-01

    Low levels of benzene from sources including cigarette smoke and automobile emissions are ubiquitous in the environment. Since the toxicity of benzene probably results from oxidative metabolites, an understanding of the profile of biotransformation of low levels of benzene is critical in making a valid risk assessment. To that end, we have investigated metabolism of a low concentration of [14C]benzene (3.4 microM) by microsomes from human, mouse and rat liver. The extent of phase I benzene metabolism by microsomal preparations from 10 human liver samples and single microsomal preparations from both mice and rats was then related to measured activities of cytochrome P450 (CYP) 2E1. Measured CYP 2E1 activities, as determined by hydroxylation of p-nitrophenol, varied 13-fold (0.253-3.266 nmol/min/mg) for human samples. The fraction of benzene metabolized in 16 min ranged from 10% to 59%. Also at 16 min, significant amounts of oxidative metabolites were formed. Phenol was the main metabolite formed by all but two human microsomal preparations. In those samples, both of which had high CYP 2E1 activity, hydroquinone was the major metabolite formed. Both hydroquinone and catechol formation showed a direct correlation with CYP 2E1 activity over the range of activities present. A simulation model was developed based on a mechanism of competitive inhibition between benzene and its oxidized metabolites, and was fit to time-course data for three human liver preparations. Model calculations for initial rates of benzene metabolism ranging from 0.344 to 4.442 nmol/mg/min are directly proportional to measured CYP 2E1 activities. The model predicted the dependence of benzene metabolism on the measured CYP 2E1 activity in human liver samples, as well as in mouse and rat liver samples. These results suggest that differences in measured hepatic CYP 2E1 activity may be a major factor contributing to both interindividual and interspecies variations in hepatic metabolism of benzene

  17. p-Benzoquinone, a reactive metabolite of benzene, prevents the processing of pre-interleukins-1{alpha} and -1{beta} to active cytokines by inhibition of the processing enzymes, calpain, and interleukin-1{beta} converting enzyme

    Energy Technology Data Exchange (ETDEWEB)

    Kalf, G.F.; Renz, J.F.; Niculescu, R. [Thomas Jefferson Univ., Philadelphia, PA (United States)

    1996-12-01

    Chronic exposure of humans to benzene affects hematopoietic stem and progenitor cells and leads to aplastic anemia. The stromal macrophage, a target of benzene toxicity, secretes interieukin-1 (IL-1), which induces the stromal fibroblast to synthesize hematopoietic colony-stimulating factors. In a mouse model, benzene causes an acute marrow hypocellularity that can be prevented by the concomitant administration of IL-1{alpha}. The ability of benzene to interfere with the production and secretion of IL-1{alpha} was tested. Stromal macrophages from benzene-treated mice were capable of the transcription of the IL-1{alpha} gene and the translation of the message but showed an inability to process the 34-kDa pre-IL-1{alpha} precursor to the 17-kDa biologically active cytokine. Treatment of normal murine stromal macrophages in culture with hydroquinone (HQ) also showed an inhibition in processing of pre-IL-1{alpha}. Hydroquinone is oxidized by a peroxidase-mediated reaction in the stromal macrophage to p-benzoquinone, which interacts with the sulfhydryl (SH) groups of proteins and was shown to completely inhibit the activity of calpain, the SH-dependent protease that cleaves pre-IL-1{alpha}. In a similar manner, HQ, via peroxidase oxidation to p-benzoquinone, was capable of preventing the IL-1{beta} autocrine stimulation of growth of human B1 myeloid tumor cells by preventing the processing of pre-IL-1{beta} to mature cytokine. Benzoquinone was also shown to completely inhibit the ability of the SH-dependent IL-1{beta} converting enzyme. Thus benzene-induced bone marrow hypocellularity may result from apoptosis of hematopoietic progenitor cells brought about by lack of essential cylokines and deficient IL-1{alpha} production subsequent to the inhibition of calpain by p-benzoquinone and the prevention of pre-IL-1 processing. 34 refs., 8 figs.

  18. Human benzene metabolism following occupational and environmental exposures.

    Science.gov (United States)

    Rappaport, Stephen M; Kim, Sungkyoon; Lan, Qing; Li, Guilan; Vermeulen, Roel; Waidyanatha, Suramya; Zhang, Luoping; Yin, Songnian; Smith, Martyn T; Rothman, Nathaniel

    2010-03-19

    We previously reported evidence that humans metabolize benzene via two enzymes, including a hitherto unrecognized high-affinity enzyme that was responsible for an estimated 73% of total urinary metabolites [sum of phenol (PH), hydroquinone (HQ), catechol (CA), E,E-muconic acid (MA), and S-phenylmercapturic acid (SPMA)] in nonsmoking females exposed to benzene at sub-saturating (ppb) air concentrations. Here, we used the same Michaelis-Menten-like kinetic models to individually analyze urinary levels of PH, HQ, CA and MA from 263 nonsmoking Chinese women (179 benzene-exposed workers and 84 control workers) with estimated benzene air concentrations ranging from less than 0.001-299 ppm. One model depicted benzene metabolism as a single enzymatic process (1-enzyme model) and the other as two enzymatic processes which competed for access to benzene (2-enzyme model). We evaluated model fits based upon the difference in values of Akaike's Information Criterion (DeltaAIC), and we gauged the weights of evidence favoring the two models based upon the associated Akaike weights and Evidence Ratios. For each metabolite, the 2-enzyme model provided a better fit than the 1-enzyme model with DeltaAIC values decreasing in the order 9.511 for MA, 7.379 for PH, 1.417 for CA, and 0.193 for HQ. The corresponding weights of evidence favoring the 2-enzyme model (Evidence Ratios) were: 116.2:1 for MA, 40.0:1 for PH, 2.0:1 for CA and 1.1:1 for HQ. These results indicate that our earlier findings from models of total metabolites were driven largely by MA, representing the ring-opening pathway, and by PH, representing the ring-hydroxylation pathway. The predicted percentage of benzene metabolized by the putative high-affinity enzyme at an air concentration of 0.001 ppm was 88% based upon urinary MA and was 80% based upon urinary PH. As benzene concentrations increased, the respective percentages of benzene metabolized to MA and PH by the high-affinity enzyme decreased successively to 66 and

  19. Human Benzene Metabolism Following Occupational and Environmental Exposures

    Science.gov (United States)

    Rappaport, Stephen M.; Kim, Sungkyoon; Lan, Qing; Li, Guilan; Vermeulen, Roel; Waidyanatha, Suramya; Zhang, Luoping; Yin, Songnian; Smith, Martyn T.; Rothman, Nathaniel

    2011-01-01

    We previously reported evidence that humans metabolize benzene via two enzymes, including a hitherto unrecognized high-affinity enzyme that was responsible for an estimated 73 percent of total urinary metabolites [sum of phenol (PH), hydroquinone (HQ), catechol (CA), E,E-muconic acid (MA), and S-phenylmercapturic acid (SPMA)] in nonsmoking females exposed to benzene at sub-saturating (ppb) air concentrations. Here, we used the same Michaelis-Menten-like kinetic models to individually analyze urinary levels of PH, HQ, CA and MA from 263 nonsmoking Chinese women (179 benzene-exposed workers and 84 control workers) with estimated benzene air concentrations ranging from less than 0.001 ppm to 299 ppm. One model depicted benzene metabolism as a single enzymatic process (1-enzyme model) and the other as two enzymatic processes which competed for access to benzene (2-enzyme model). We evaluated model fits based upon the difference in values of Akaike’s Information Criterion (ΔAIC), and we gauged the weights of evidence favoring the two models based upon the associated Akaike weights and Evidence Ratios. For each metabolite, the 2-enzyme model provided a better fit than the 1-enzyme model with ΔAIC values decreasing in the order 9.511 for MA, 7.379 for PH, 1.417 for CA, and 0.193 for HQ. The corresponding weights of evidence favoring the 2-enzyme model (Evidence Ratios) were: 116.2:1 for MA, 40.0:1 for PH, 2.0:1 for CA and 1.1:1 for HQ. These results indicate that our earlier findings from models of total metabolites were driven largely by MA, representing the ring-opening pathway, and by PH, representing the ring-hydroxylation pathway. The predicted percentage of benzene metabolized by the putative high-affinity enzyme at an air concentration of 0.001 ppm was 88% based upon urinary MA and was 80% based upon urinary PH. As benzene concentrations increased, the respective percentages of benzene metabolized to MA and PH by the high-affinity enzyme decreased successively

  20. Simultaneous determination of benzene, toluene, ethylbenzene, and xylene metabolites in human urine using electromembrane extraction combined with liquid chromatography and tandem mass spectrometry.

    Science.gov (United States)

    Suh, Joon Hyuk; Lee, Hye Yeon; Kim, Unyong; Eom, Han Young; Kim, Junghyun; Cho, Hyun-Deok; Han, Sang Beom

    2015-12-01

    For the first time, electromembrane extraction combined with liquid chromatography and tandem mass spectrometry was applied for the determination of urinary benzene, toluene, ethylbenzene, and xylene metabolites. S-Phenylmercapturic acid, hippuric acid, phenylglyoxylic acid, and methylhippuric acid isomers were extracted from human urine through a supported liquid membrane consisting of 1-octanol into an alkaline acceptor solution filling the inside of a hollow fiber by application of an electric field. Various extraction factors were investigated and optimized using response surface methodology, the statistical method. The optimum conditions were established to be 300 V applied voltage, 15 min extraction time, 1500 rpm stirring speed, and 5 mM ammonium acetate (pH 10.2) acceptor solution. The method was validated with respect to selectivity, linearity, accuracy, precision, limit of detection, limit of quantification, recovery, and reproducibility. The results showed good linearity (r(2) > 0.995), precision, and accuracy. The extract recoveries were 52.8-79.0%. Finally, we applied this method to real samples and successfully measured benzene, toluene, ethylbenzene, and xylene metabolites. PMID:26500147

  1. Metabolism of trans, trans-muconaldehyde, a cytotoxic metabolite of benzene, in mouse liver by alcohol dehydrogenase Adh1 and aldehyde reductase AKR1A4

    International Nuclear Information System (INIS)

    The reductive metabolism of trans, trans-muconaldehyde, a cytotoxic metabolite of benzene, was studied in mouse liver. Using an HPLC-based stopped assay, the primary reduced metabolite was identified as 6-hydroxy-trans, trans-2,4-hexadienal (OH/CHO) and the secondary metabolite as 1,6-dihydroxy-trans, trans-2,4-hexadiene (OH/OH). The main enzymes responsible for the highest levels of reductase activity towards trans, trans-muconaldehyde were purified from mouse liver soluble fraction first by Q-sepharose chromatography followed by either blue or red dye affinity chromatography. In mouse liver, trans, trans-muconaldehyde is predominantly reduced by an NADH-dependent enzyme, which was identified as alcohol dehydrogenase (Adh1). Kinetic constants obtained for trans, trans-muconaldehyde with the native Adh1 enzyme showed a V max of 2141 ± 500 nmol/min/mg and a K m of 11 ± 4 μM. This enzyme was inhibited by pyrazole with a K I of 3.1 ± 0.57 μM. Other fractions were found to contain muconaldehyde reductase activity independent of Adh1, and one enzyme was identified as the NADPH-dependent aldehyde reductase AKR1A4. This showed a V max of 115 nmol/min/mg and a K m of 15 ± 2 μM and was not inhibited by pyrazole

  2. RATE AND CAPACITY OF HEPATIC MICROSOMAL RING HYDROXYLATION OF PHENOL TO HYDROQUINONE AND CATECHOL IN RAINBOW TROUT

    Science.gov (United States)

    Rainbow trout (Oncorhynchus mykiss) liver microsomes were used to study the rate of ring-hydroxylation of phenol PH) by directly measuring the production of hydroquinone (HQ), the primary metabolite, and catechol (CAT), a secondary metabolite. An HPLC method with integrated ultra...

  3. RATE AND CAPACITY OF HEPATIC MICROSOMAL RING HYDROXYLATION OF PHENOL TO HYDROQUINONE AND CATECHOL IN RAINBOW TROUT (ONCORHYNCHUS MYKISS)

    Science.gov (United States)

    Rainbow trout liver microsomes were used to study the rate of ring-hydroxylation of phenol (PH) by directly measuring the production of hydroquinone (HQ), the primary metabolite, and catechol (CAT), a secondary metabolite. An HPLC method with integrated ultroviolet (UV) and elect...

  4. 32P analysis of DNA adducts in tissues of benzene-treated rats

    International Nuclear Information System (INIS)

    Solid tumors have been reported in the Zymbal gland, oral and nasal cavities, liver, and mammary gland of Sprague-Dawley rats following chronic, high-dose administration of benzene. The carcinogenic activity of benzene is thought to be caused by activation to toxic metabolites that can interact with DNA, forming covalent adducts. A nuclease P1-enhanced 32P-postlabeling assay, having a sensitivity limit of 1 adduct in 10(9-10) DNA nucleotides, was found suitable for measuring aromatic DNA adducts derived in vitro from catechol, benzenetriol (BT), phenol, hydroquinone (HQ), and benzoquinone (BQ), potential metabolites of benzene. When DNA specimens isolated from tissues of female Sprague-Dawley rats at 24 hr after an oral gavage dose of 200 to 500 mg/kg, 5 days/week, in olive oil (3 mL/kg) for 1 day, 1 week, 5 weeks, and 10 weeks were analyzed by the 32P-postlabeling procedure, no aromatic adducts were detected unequivocally with DNA samples of liver, kidney, bone marrow, and mammary gland. With Zymbal gland DNA, three weak spots at levels totaling four lesions per 10(9) DNA nucleotides were seen only after 10 weeks of treatment, and these adducts did not correspond chromatographically to major adducts in vitro from the above specified compounds. Consequently, this finding requires confirmatory experiments. This distinct adduct pattern may relate to tumor induction in this organ following benzene administration. Our results also indicate that DNA adducts derived from catechol, BT, phenol, HQ, and BQ are either not formed in vivo with benzene or formed at levels below the detection limit of 1 adduct per 10(9-10) DNA nucleotides

  5. Quantitative analysis of arbutin and hydroquinone in strawberry tree (Arbutus unedo L., Ericaceae) leaves by gas chromatography-mass spectrometry.

    Science.gov (United States)

    Jurica, Karlo; Karačonji, Irena Brčić; Šegan, Sandra; Opsenica, Dušanka Milojković; Kremer, Dario

    2015-09-01

    The phenolic glycoside arbutin and its metabolite with uroantiseptic activity hydroquinone occur naturally in the leaves of various medicinal plants and spices. In this study, an extraction procedure coupled with gas chromatography-mass spectrometry (GC-MS) was developed to determine arbutin and hydroquinone content in strawberry tree (Arbutus unedo L., Ericaceae) leaves. The method showed good linearity (R2>0.9987) in the tested concentration range (0.5-200 μg mL(-1)), as well as good precision (RSDarbutin and hydroquinone, respectively). The results obtained by the validated GC-MS method corresponded well to those obtained by high performance liquid chromatography (HPLC) method. The proposed method was then applied for determining arbutin and hydroquinone content in methanolic leaf extracts. The amount of arbutin in the leaves collected on the island of Koločep (6.82 mg g(-1) dry weight) was found to be higher (tpaired=43.57, tc=2.92) in comparison to the amount of arbutin in the leaves collected on the island of Mali Lošinj (2.75 mg g(-1) dry weight). Hydroquinone was not detected in any of the samples. The analytical features of the proposed GC-MS method demonstrated that arbutin and hydroquinone could be determined alternatively by gas chromatography. Due to its wide concentration range, the method could also be suitable for arbutin and hydroquinone analysis in leaves of other plant families (Rosaceae, Lamiaceae, etc.). PMID:26444340

  6. Human exposure to naturally occurring hydroquinone.

    Science.gov (United States)

    Deisinger, P J; Hill, T S; English, J C

    1996-01-01

    Hydroquinone (HQ) is a nonvolatile chemical used in the photographic, rubber, chemical, and cosmetic industries. HQ is also known to occur in nature as the beta-D-glucopyranoside conjugate (arbutin), and free HQ is a known component of cigarette smoke. Low concentrations of HQ have been detected in the urine and plasma of humans with no occupational or other known exposure to HQ. The studies reported here investigate dietary and other potential sources of HQ and their contribution to HQ concentrations in the plasma and urine of human volunteers. Analysis of possible food sources of HQ by GC indicated significant amounts of arbutin in wheat products (1-10 ppm), pears (4-15 ppm), and coffee and tea (0.1 ppm). Free HQ was found in coffee (0.2 ppm), red wine (0.5 ppm), wheat cereals (0.2-0.4 ppm), and broccoli (0.1 ppm). After consuming a meal including arbutin- and HQ-containing foods, volunteers showed significant increases in plasma and urinary levels of HQ and its conjugated metabolites (total HQ). Mean plasma concentrations of total HQ peaked at 5 times background levels at 2 h after the completion of the meal, and mean urinary excretion rates of total HQ peaked at 12 times background at 2-3 h after the meal. Immediately after smoking four cigarettes in approximately 30 min, mean plasma concentrations of total HQ were maximally 1.5 times background levels; mean urinary excretion rates of total HQ peaked at 2.5 times background at 1-3 h after smoking. These data indicate that considerable human exposure to HQ can result from plant-derived dietary sources and, to a lesser extent, from cigarette smoke. PMID:8568910

  7. Biotransformation of phenol to hydroquinone and catechol by rat liver microsomes.

    Science.gov (United States)

    Sawahata, T; Neal, R A

    1983-03-01

    Hepatic microsomal biotransformation of phenol to hydroquinone and catechol has been investigated with special reference to the covalent binding to microsomal protein of reactive metabolites formed during microsomal metabolism of phenol. Incubation of [14C]phenol with microsomes from phenobarbital-treated rat liver in the presence of an NADPH-generating system resulted in the formation of hydroquinone and catechol in the ratio of 20:1. No significant formation of 1,2,4-benzenetriol was observed. The biotransformation of phenol to both hydroquinone and catechol required NADPH and molecular oxygen. NADH was much less effective than NADPH as an electron donor and exhibited no significant synergistic effect when used together with NADPH. The biotransformation was inhibited by typical cytochrome P-450 inhibitors such as carbon monoxide, SKF 525-A, and metyrapone. These results indicated the involvement of cytochrome P-450 in the microsomal hydroxylation of phenol at both the ortho- and para-positions. Covalent binding of radioactivity to microsomal protein was observed when [14C]phenol was incubated with rat liver microsomes in the presence of an NADPH-generating system. The covalent binding was also found to require NADPH and molecular oxygen. Inclusion of cytochrome P-450 inhibitors in the incubation mixture resulted in a decrease in the covalent binding. These results indicated that at least one step in the metabolic activation of phenol to the metabolites responsible for covalent binding to microsomal protein was mediated by cytochrome P-450. Inclusion of N-acetylcysteine in the incubation mixture resulted in the complete inhibition of the covalent binding of radioactivity derived from [14C]phenol to microsomal protein, and there was a concomitant formation of N-acetylcysteine adducts of hydroquinone and catechol. These results indicated that hydroquinone and catechol were both precursors to reactive metabolites responsible for the covalent binding. PMID:6835203

  8. Effect of repeated benzene inhalation exposures on benzene metabolism, binding to hemoglobin, and induction of micronuclei

    International Nuclear Information System (INIS)

    Metabolism of benzene is thought to be necessary to produce the toxic effects, including carcinogenicity, associated with benzene exposure. To extrapolate from the results of rodent studies to potential health risks in man, one must know how benzene metabolism is affected by species, dose, dose rate, and repeated versus single exposures. The purpose of our studies was to determine the effect of repeated inhalation exposures on the metabolism of [14C]benzene by rodents. Benzene metabolism was assessed by characterizing and quantitating urinary metabolites, and by quantitating 14C bound to hemoglobin and micronuclei induction. F344/N rats and B6C3F1 mice were exposed, nose-only, to 600 ppm benzene or to air (control) for 6 hr/day, 5 days/week for 3 weeks. On the last day, both benzene-pretreated and control animals were exposed to 600 ppm, 14C-labeled benzene for 6 hr. Individual benzene metabolites in urine collected for 24 hr after the exposure were analyzed. There was a significant decrease in the respiratory rate of mice (but not rats) pretreated with benzene which resulted in lower levels of urinary [14C]benzene metabolites. The analyses indicated that the only effects of benzene pretreatment on the metabolite profile in rat or mouse urine were a slight shift from glucuronidation to sulfation in mice and a shift from sulfation to glucuronidation in rats. Benzene pretreatment also had no effect, in either species, on formation of [14C]benzene-derived hemoglobin adducts. Mice and rats had similar levels of hemoglobin adduct binding, despite the higher metabolism of benzene by mice. This indicates that hemoglobin adduct formation occurs with higher efficiency in rats. After 1 week of exposure to 600 ppm benzene, the frequency of micronucleated, polychromatic erythrocytes (PCEs) in mice was significantly increased

  9. New high-performance liquid chromatography-dad method for analytical determination of arbutin and hydroquinone in rat plasma

    Directory of Open Access Journals (Sweden)

    F R Gallo

    2015-01-01

    Full Text Available Natural substances present in herbal preparations should be carefully used because they can give toxic or therapeutic effects despite of their amount or the way of administration. The safety of products of vegetable origin must be assessed before commercialisation by monitoring the active ingredients and their metabolites. This study was therefore designed to identify and quantify arbutin and its metabolite hydroquinone, naturally present in Arctostaphylos uva-ursi (L. Spreng plant in rat plasma, after an acute and subacute administration of aqueous arbutin solution in Wistar rats. For this purpose a reversed-phase high-performance liquid chromatography coupled with photodiode array detection was developed to assess the pharmacokinetic of arbutin and hydroquinone in plasma of female rats treated with aqueous arbutin solutions. The detection (arbutin: 0.0617 µg/ml and hydroquinone 0.0120 µg/ml and quantification (arbutin: 0.2060 µg/ml and hydroquinone: 0.0400 µg/ml limits were determined. At the arbutin concentration level of 10.7 µg/ml repeatability was 13.33% and its recovery 93.4±6.93%, while at the hydroquinone concentration level of 10.6 µg/ml repeatability was 11.66% and its recovery 92.9±7.75%. Furthermore the method was fully validated and the obtained data indicate that the new method provides good performances.

  10. New High-performance Liquid Chromatography-DAD Method for Analytical Determination of Arbutin and Hydroquinone in Rat Plasma.

    Science.gov (United States)

    Gallo, F R; Pagliuca, G; Multari, G; Panzini, G; D'amore, E; Altieri, I

    2015-01-01

    Natural substances present in herbal preparations should be carefully used because they can give toxic or therapeutic effects despite of their amount or the way of administration. The safety of products of vegetable origin must be assessed before commercialisation by monitoring the active ingredients and their metabolites. This study was therefore designed to identify and quantify arbutin and its metabolite hydroquinone, naturally present in Arctostaphylos uva-ursi (L.) Spreng plant in rat plasma, after an acute and subacute administration of aqueous arbutin solution in Wistar rats. For this purpose a reversed-phase high-performance liquid chromatography coupled with photodiode array detection was developed to assess the pharmacokinetic of arbutin and hydroquinone in plasma of female rats treated with aqueous arbutin solutions. The detection (arbutin: 0.0617 µg/ml and hydroquinone 0.0120 µg/ml) and quantification (arbutin: 0.2060 µg/ml and hydroquinone: 0.0400 µg/ml) limits were determined. At the arbutin concentration level of 10.7 µg/ml repeatability was 13.33% and its recovery 93.4±6.93%, while at the hydroquinone concentration level of 10.6 µg/ml repeatability was 11.66% and its recovery 92.9±7.75%. Furthermore the method was fully validated and the obtained data indicate that the new method provides good performances. PMID:26798166

  11. Radioactive scanning agents with hydroquinone stabilizer

    International Nuclear Information System (INIS)

    Stable compositions useful as technetium 99m-based scintigraphic agents comprise hydroquinone in combination with a pertechnetate reducing agent or dissolved in pertechnetate-99m (sup(99m)TcOsub(4)sup(-)) solution. The compositions are especially useful in combination with a phosphate or phosphonate material which carries the radionuclide to bone, thus providing a skeletal imaging agent

  12. Differences in xenobiotic detoxifying activities between bone marrow stromal cells from mice and rats: Implications for benzene-induced hematotoxicity

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Hong; Li, Yunbo; Trush, M.A. [Johns Hopkins Univ. School of Hygiene and Public Health, Baltimore, MD (United States)

    1995-10-01

    benzene is a human carcinogen; exposure can result in aplastic anemia and leukemia. Data from animal models are frequently used in benzene risk assessment. In rodent studies, mice are more sensitive to benzene-induced hematotoxicity than rats. Bone marrow stromal cells from mice were significantly more susceptible to the cytotoxicity induced by the benzene metabolites hydroquinone (HQ) and benzoquinone (BQ) than cells from rats. Since cellular gluthathione (GSH) and quinone reductase (QR) are known to play critical roles in modulating HQ-induced cytotoxicity, the GSH content and the QR and glutathione S-transferase (GST) activity in stromal cells from both species was measured. In rat cells, the GSH content and the QR specific activity were 2 and 28 times as much as those from mice, respectively. GSH and QR in both mouse and rat stromal cells were inducible by 1,2-dithiole-3-thione (D3T). D3T pretreatment of both mouse and rat stromal cells resulted in a marked protection against HQ-induced toxicity. Pretreatment of both mouse and rat stromal cells with GSH ethyl ester also provided a dramatic protection against HQ-induced toxicity. Conversely, dicoumarol, an inhibitor of QR, enhanced the HQ-induced toxicity in stromal cells from both mice and rats, indicating an important role for QR in modulating HQ-induced stromal toxicity. Buthionine sulfoximine (BSO), which depleted GSH significantly in both species, potentiated the HQ-induced toxicity in mouse but not in rat stromal cells. Surprisingly, incubation of stromal cells with BSO resulted in a significant induction of QR, especially in rats. Overall, this study demonstrates that the differences in stromal cellular GSH content and QR activity between mice and rats contribute to their respective susceptibility to HQ-induced cytotoxicity in vitro, and may be involved in the greater in vivo sensitivity of mice to benzene-induced hematotoxicity. 51 refs., 9 figs., 1 tab.

  13. The First Total Synthesis of Triprenylquinone and Hydroquinones

    Institute of Scientific and Technical Information of China (English)

    Chun Hong LI; Xue Song CHEN; Guang Lian ZHOU; Zhi Xiang XIE; Ying LI

    2005-01-01

    First total synthesis of triprenylquinone and hydroquinones, three naturally occurring compound 1, 2 and (±) 3, have been achieved from readily available 2-bromo-5-methyl-1,4-dimethoxybenzene 4 and geranyl bromide. The triprenylquinone and hydroquinones precursor were readily prepared with use of a Julia reaction.

  14. Dihydroxy-Benzenes as Corrosion Inhibitors for Aluminium Sheet in Alkali Solution

    International Nuclear Information System (INIS)

    Additions of dihydroxy-benzenes (such as catechol, hydeoquinione and resorcinol)as corrosion inhibitors decrease the corrosion of aluminium sheet (which is given in the market) in 0.1M-1.0M sodium hydroxide solutions. The decrease is dependent upon the concentration of the sodium hydroxide and that of the inhibitor. Inhibitive efficiency is resorcinol < catechol< hydroquinone< resorcinol+hydroquinone at a concentration of 0.005% (w/w) dihydroxy-benzenes, and catechol< hydroquinone< resorcinol< resorcinol+hydroquinone at 0.5%, whereas the efficiency of all three inhibitors reaches approximately 100% at a concentration of 2% inhibitors in 0.1M NaOH. No correlation appears to exist between the inhibitor efficiency and the dissociation constant (Pk values) of the inhibitor. It can be said that 0.5M concentration of sodium hydroxide is the fittest for reducing the aluminium sheet by hydroquinone and formation of catechol-aluminium complex ions in the sodium hydroxide solutions

  15. Benzene oxygenation and oxidation by the peroxygenase of Agrocybe aegerita.

    Science.gov (United States)

    Karich, Alexander; Kluge, Martin; Ullrich, René; Hofrichter, Martin

    2013-01-01

    Aromatic peroxygenase (APO) is an extracellular enzyme produced by the agaric basidiomycete Agrocybe aegerita that catalyzes diverse peroxide-dependent oxyfunctionalization reactions. Here we describe the oxygenation of the unactivated aromatic ring of benzene with hydrogen peroxide as co-substrate. The optimum pH of the reaction was around 7 and it proceeded via an initial epoxide intermediate that re-aromatized in aqueous solution to form phenol. Identity of the epoxide intermediate as benzene oxide was proved by a freshly prepared authentic standard using GC-MS and LC-MS analyses. Second and third [per]oxygenation was also observed and resulted in the formation of further hydroxylation and following [per]oxidation products: hydroquinone and p-benzoquinone, catechol and o-benzoquinone as well as 1,2,4-trihydroxybenzene and hydroxy-p-benzoquinone, respectively. Using H218O2 as co-substrate and ascorbic acid as radical scavenger, inhibiting the formation of peroxidation products (e.g., p-benzoquinone), the origin of the oxygen atom incorporated into benzene or phenol was proved to be the peroxide. Apparent enzyme kinetic constants (kcat, Km) for the peroxygenation of benzene were estimated to be around 8 s-1 and 3.6 mM. These results raise the possibility that peroxygenases may be useful for enzymatic syntheses of hydroxylated benzene derivatives under mild conditions. PMID:23327645

  16. Benzene from Traffic

    DEFF Research Database (Denmark)

    Palmgren, F.; Berkowicz, R.; Skov, H.;

    The measurements of benzene showed very clear decreasing trends in the air concentrations and the emissions since 1994. At the same time the measurements of CO and NOx also showed a decreasing trend, but not so strong as for benzene. The general decreasing trend is explained by the increasing...... number of petrol vehicles with three way catalysts, 60-70% in 1999. The very steep decreasing trend for benzene at the beginning of the period from 1994 was explained by the combination of more catalyst vehicles and reduced benzene content in Danish petrol. The total amount of aromatics in petrol......, including toluene, increased only weakly. The analyses of air concentrations were confirmed by analyses of petrol sold in Denmark. The concentration of benzene at Jagtvej in Copenhagen is still in 1998 above the expected new EU limit value, 5 µg/m3 as annual average. However, the reduced content of benzene...

  17. Densities and Kinematic Viscosities for the Systems Benzene + Methyl Formate, Benzene + Ethyl Formate, Benzene + Propyl Formate, and Benzene + Butyl Formate

    DEFF Research Database (Denmark)

    Emmerling, Uwe; Rasmussen, Peter

    1998-01-01

    Densities and kinematic viscosities have been measured for the system benzene + methyl formate at 20°C and for the systems benzene + ethyl formate, benzene + propyl formate, and benzene + butyl formate from 20°C to 50°C. The results for the system benzene + methyl formate have been correlated using...... a Redlich-Kister type of expression with temperature-independent parameters and the data for the systems benzene + ethyl formate, benzene + propyl formate, and benzene + butyl formate with temperature-dependent parameters. The viscosities have furthermore been compared to values predicted by means...

  18. Benzene exposure is associated with epigenetic changes (Review).

    Science.gov (United States)

    Fenga, Concettina; Gangemi, Silvia; Costa, Chiara

    2016-04-01

    Benzene is a volatile aromatic hydrocarbon solvent and is known as one of the predominant air pollutants in the environment. Chronic exposure to benzene is known to cause aplastic anemia and increased risk of acute myelogenous leukemia in humans. Although the mechanisms by which benzene causes toxicity remain to be fully elucidated, it is widely accepted that its metabolism is crucial to its toxicity, with involvement of one or more reactive metabolites. Novel approaches aimed at evaluating different mechanisms by which benzene can impact on human health by altering gene regulation have been developed. Among these novel approaches, epigenetics appears to be promising. The present review article summarizes the most important findings, reported from the literature, on epigenetic modifications correlated to benzene exposure. A computerized search in PubMed was performed in November 2014, using search terms, including 'benzene', 'epigenetic', 'histone modifications', 'DNA methylation' and 'microRNA'. Epidemiological and experimental studies have demonstrated the potential epigenetic effects of benzene exposure. Several of the epigenomic changes observed in response to environmental exposures may be mechanistically associated with susceptibility to diseases. However, further elucidation of the mechanisms by which benzene alters gene expression may improve prediction of the toxic potential of novel compounds introduced into the environment, and allow for more targeted and appropriate disease prevention strategies. PMID:26936331

  19. Case report: hydroquinone and/or glutaraldehyde induced acute myeloid leukaemia?

    Directory of Open Access Journals (Sweden)

    Alexopoulos Evangelos C

    2006-07-01

    Full Text Available Abstract Background Exposures to high doses of irradiation, to chemotherapy, benzene, petroleum products, paints, embalming fluids, ethylene oxide, herbicides, pesticides, and smoking have been associated with an increased risk of acute myelogenous leukemia (AML. Although there in no epidemiological evidence of relation between X-ray developer, fixer and replenisher liquids and AML, these included glutaraldehyde which has weakly associated with lymphocytic leukemia in rats and hydroquinone has been increasingly implicated in producing leukemia, causing DNA and chromosomal damage, inhibits topo-isomerase II, alter hematopoiesis and inhibit apoptosis of neoplastic cells. Case presentation Two white females (A and B hired in 1985 as medical radiation technologists in a primary care center, in Greece. In July 2001, woman A, 38-years-old, was diagnosed as having acute monocytic leukaemia (FAB M5. The patient did not respond to therapy and died threeweeks later. In August 2001, woman B, 35-year-old, was diagnosed with acute promyelocytic leukaemia (FAB M3. Since discharge, she is in continuous complete remission. Both women were non smokers without any medical history. Shortly after these incidents official inspectors and experts inspected workplace, examined equipment, archives of repairs, notes, interviewed and monitored employees. They concluded that shielding was inadequate for balcony's door but personal monitoring did not show any exceeding of TLV of 20 mSv yearly and cytogenetics analysis did not reveal findings considered to be characteristics of ionizing exposure. Equipment for developing photos had a long list of repairs, mainly leakages of liquids and increases of temperature. On several occasions the floor has been flooded especially during 1987–1993 and 1997–2001. Inspection confirmed a complete lack of ventilation and many spoiled medical x-ray films. Employees reported that an "osmic" level was continuously evident and frequently

  20. Possible Role of DNA Polymerase beta in Protecting Human Bronchial Epithelial Cells Against Cytotoxicity of Hydroquinone

    Institute of Scientific and Technical Information of China (English)

    DA-LIN HU; JIAN-PING YANG; DAO-KUI FANG; YAN SHA; XIAO-ZHI TU; ZHI-XIONG ZHUANG; HUAN-WEN TANG; HAI-RONG LIANG; DONG-SHENG TANG; YI-MING LIU; WEI-DONG JI; JIAN-HUI YUAN; YUN HE; ZHENG-YU ZHU

    2007-01-01

    Objective To explore the toxicological mechanism of hydroquinone in human bronchial epithelial cells and to investigate whether DNA polymerase beta is involved in protecting cells from damage caused by hydroquinone. Methods DNA polymerase beta knock-down cell line was established via RNA interference as an experimental group. Normal human bronchial epithelial cells and cells transfected with the empty vector of pEGFP-Cl were used as controls. Cells were treated with different concentrations of hydroquinone (ranged from 10 μmol/L to 120 μmol/L) for 4 hours. MTT assay and Comet assay [single-cell gel electrophoresis (SCGE)] were performed respectively to detect the toxicity of hydroquinone. Results MTT assay showed that DNA polymerase beta knock-down cells treated with different concentrations of hydroquinone had a lower absorbance value at 490 nm than the control cells in a dose-dependant manner. Comet assay revealed that different concentrations of hydroquinone caused more severe DNA damage in DNA polymerase beta knock-down cell line than in control cells and there was no significant difference in the two control groups. Conclusions Hydroquinone has significant toxicity to human bronchial epithelial cells and causes DNA damage. DNA polymerase beta knock-down cell line appears more sensitive to hydroquinone than the control cells. The results suggest that DNA polymerase beta is involved in protecting cells from damage caused by hydroquinone.

  1. Benzene release. Status report

    International Nuclear Information System (INIS)

    Scoping benzene release measurements were conducted on 4 wt percent KTPB 'DEMO' formulation slurry using a round, flat bottomed 100-mL flask containing 75 mL slurry. The slurry was agitated with a magnetic stirrer bar to keep the surface refreshed without creating a vortex. Benzene release measurements were made by purging the vapor space at a constant rate and analyzing for benzene by gas chromatography with automatic data acquisition. Some of the data have been rounded or simplified in view of the scoping nature of this study

  2. FORMATION OF HEMOGLOBIN AND ALBUMIN ADDUCTS OF BENZENE OXIDE IN MOUSE, RAT, AND HUMAN BLOOD

    Science.gov (United States)

    Little is known about the formation and disposition of benzene oxide (BO), the initial metabolite arising from oxidation of benzene by cytochrome P450. In this study, reactions of BO with hemoglobin (Hb) and albumin (Alb) were investigated in blood from B6C3F1 mice, F344 rats, ...

  3. Benzene exposure: an overview of monitoring methods and their findings.

    Science.gov (United States)

    Weisel, Clifford P

    2010-03-19

    Benzene has been measured throughout the environment and is commonly emitted in several industrial and transportation settings leading to widespread environmental and occupational exposures. Inhalation is the most common exposure route but benzene rapidly penetrates the skin and can contaminant water and food resulting in dermal and ingestion exposures. While less toxic solvents have been substituted for benzene, it still is a component of petroleum products, including gasoline, and is a trace impurity in industrial products resulting in continued sub to low ppm occupational exposures, though higher exposures exist in small, uncontrolled workshops in developing countries. Emissions from gasoline/petrochemical industry are its main sources to the ambient air, but a person's total inhalation exposure can be elevated from emissions from cigarettes, consumer products and gasoline powered engines/tools stored in garages attached to homes. Air samples are collected in canisters or on adsorbent with subsequent quantification by gas chromatography. Ambient air concentrations vary from sub-ppb range, low ppb, and tens of ppb in rural/suburban, urban, and source impacted areas, respectively. Short-term environmental exposures of ppm occur during vehicle fueling. Indoor air concentrations of tens of ppb occur in microenvironments containing indoor sources. Occupational and environmental exposures have declined where regulations limit benzene in gasoline (<1%) and cigarette smoking has been banned from public and work places. Similar controls should be implemented worldwide to reduce benzene exposure. Biomarkers of benzene used to estimate exposure and risk include: benzene in breath, blood and urine; its urinary metabolites: phenol, t,t-muconic acid (t,tMA) and S-phenylmercapturic acid (sPMA); and blood protein adducts. The biomarker studies suggest benzene environmental exposures are in the sub to low ppb range though non-benzene sources for urinary metabolites, differences

  4. Facts about Benzene

    Science.gov (United States)

    ... Lab Info Chemical Emergencies A–Z Abrin Adamsite Ammonia Arsenic Arsine Barium Benzene Brevetoxin Bromine BZ Carbon ... used to make some types of lubricants, rubbers, dyes, detergents, drugs, and pesticides. How you could be ...

  5. Benzene Monitor System report

    Energy Technology Data Exchange (ETDEWEB)

    Livingston, R.R.

    1992-10-12

    Two systems for monitoring benzene in aqueous streams have been designed and assembled by the Savannah River Technology Center, Analytical Development Section (ADS). These systems were used at TNX to support sampling studies of the full-scale {open_quotes}SRAT/SME/PR{close_quotes} and to provide real-time measurements of benzene in Precipitate Hydrolysis Aqueous (PHA) simulant. This report describes the two ADS Benzene Monitor System (BMS) configurations, provides data on system operation, and reviews the results of scoping tests conducted at TNX. These scoping tests will allow comparison with other benzene measurement options being considered for use in the Defense Waste Processing Facility (DWPF) laboratory. A report detailing the preferred BMS configuration statistical performance during recent tests has been issued under separate title: Statistical Analyses of the At-line Benzene Monitor Study, SCS-ASG-92-066. The current BMS design, called the At-line Benzene Monitor (ALBM), allows remote measurement of benzene in PHA solutions. The authors have demonstrated the ability to calibrate and operate this system using peanut vials from a standard Hydragard{trademark} sampler. The equipment and materials used to construct the ALBM are similar to those already used in other applications by the DWPF lab. The precision of this system ({+-}0.5% Relative Standard Deviation (RSD) at 1 sigma) is better than the purge & trap-gas chromatograpy reference method currently in use. Both BMSs provide a direct measurement of the benzene that can be purged from a solution with no sample pretreatment. Each analysis requires about five minutes per sample, and the system operation requires no special skills or training. The analyzer`s computer software can be tailored to provide desired outputs. Use of this system produces no waste stream other than the samples themselves (i.e. no organic extractants).

  6. Degradation of Benzene by Using a Silent-Packed Bed Hybrid Discharge Plasma Reactor

    Institute of Scientific and Technical Information of China (English)

    姜楠; 鲁娜; 李杰; 吴彦

    2012-01-01

    In this work, a novel gas phase silent-packed bed hybrid discharge plasma reactor has been proposed, and its ability to control a simulative gas stream containing 240 ppm benzene is experimentally investigated. In order to optimize the geometry of the reactor, the benzene conversion rate and energy yield (EY) were compared for various inner electrode diameters and quartz tube shapes and sizes. In addition, benzene removal efficiency in different discharge regions was qualitatively analyzed and the gas parameter (space velocity) was systematically studied. It has been found that silent-packed bed hybrid discharge plasma reactor can effectively decompose benzene. Benzene removal proved to achieve an optimum value of 60% with a characteristic energy density of 255 J/L in this paper with a 6 mm bolt high-voltage electrode and a 13 mm quartz tube. The optimal space velocity was 188.1 h^-1, which resulted in moderate energy yield and removal efficiency. Reaction by-products such as hydroquinone, heptanoic acid, 4-nitrocatechol, phenol and 4-phenoxy-phenol were identified by mean of GC-MS. In addition, based on these organic by-products, a benzene destruction pathway was proposed.

  7. Degradation of Benzene by Using a Silent-Packed Bed Hybrid Discharge Plasma Reactor

    Science.gov (United States)

    Jiang, Nan; Lu, Na; Li, Jie; Wu, Yan

    2012-02-01

    In this work, a novel gas phase silent-packed bed hybrid discharge plasma reactor has been proposed, and its ability to control a simulative gas stream containing 240 ppm benzene is experimentally investigated. In order to optimize the geometry of the reactor, the benzene conversion rate and energy yield (EY) were compared for various inner electrode diameters and quartz tube shapes and sizes. In addition, benzene removal efficiency in different discharge regions was qualitatively analyzed and the gas parameter (space velocity) was systematically studied. It has been found that silent-packed bed hybrid discharge plasma reactor can effectively decompose benzene. Benzene removal proved to achieve an optimum value of 60% with a characteristic energy density of 255 J/L in this paper with a 6 mm bolt high-voltage electrode and a 13 mm quartz tube. The optimal space velocity was 188.1 h-1, which resulted in moderate energy yield and removal efficiency. Reaction by-products such as hydroquinone, heptanoic acid, 4-nitrocatechol, phenol and 4-phenoxy-phenol were identified by mean of GC-MS. In addition, based on these organic by-products, a benzene destruction pathway was proposed.

  8. Benzene-derived N2-(4-hydroxyphenyl)-deoxyguanosine adduct: UvrABC incision and its conformation in DNA

    Energy Technology Data Exchange (ETDEWEB)

    Hang, Bo; Rodriguez, Ben; Yang, Yanu; Guliaev, Anton B.; Chenna, Ahmed

    2010-06-14

    Benzene, a ubiquitous human carcinogen, forms DNA adducts through its metabolites such as p-benzoquinone (p-BQ) and hydroquinone (HQ). N(2)-(4-Hydroxyphenyl)-2'-deoxyguanosine (N(2)-4-HOPh-dG) is the principal adduct identified in vivo by (32)P-postlabeling in cells or animals treated with p-BQ or HQ. To study its effect on repair specificity and replication fidelity, we recently synthesized defined oligonucleotides containing a site-specific adduct using phosphoramidite chemistry. We here report the repair of this adduct by Escherichia coli UvrABC complex, which performs the initial damage recognition and incision steps in the nucleotide excision repair (NER) pathway. We first showed that the p-BQ-treated plasmid was efficiently cleaved by the complex, indicating the formation of DNA lesions that are substrates for NER. Using a 40-mer substrate, we found that UvrABC incises the DNA strand containing N(2)-4-HOPh-dG in a dose- and time-dependent manner. The specificity of such repair was also compared with that of DNA glycosylases and damage-specific endonucleases of E. coli, both of which were found to have no detectable activity toward N(2)-4-HOPh-dG. To understand why this adduct is specifically recognized and processed by UvrABC, molecular modeling studies were performed. Analysis of molecular dynamics trajectories showed that stable G:C-like hydrogen bonding patterns of all three Watson-Crick hydrogen bonds are present within the N(2)-4-HOPh-G:C base pair, with the hydroxyphenyl ring at an almost planar position. In addition, N(2)-4-HOPh-dG has a tendency to form more stable stacking interactions than a normal G in B-type DNA. These conformational properties may be critical in differential recognition of this adduct by specific repair enzymes.

  9. Using Poly-L-Histidine Modified Glassy Carbon Electrode to Trace Hydroquinone in the Sewage Water

    Directory of Open Access Journals (Sweden)

    Bin Wang

    2014-01-01

    Full Text Available A sensitive voltammetric method for trace measurements of hydroquinone in the sewage water is described. The poly-L-histidine is prepared to modify the glassy carbon electrode in order to improve the electrochemical catalysis of interesting substances such as hydroquinone. The influence of the base solution, pH value, and scanning speed on the tracing of hydroquinone is discussed, and the experimental procedures and conditions are optimized. The laboratory results show that it is possible to construct a linear calibration curve between the peak current of hydroquinone on modified electrode and its concentration at the level of 0.00001 mol/L. The potential limitation of the method is suggested by a linear peaking shift model as well. The method was successfully applied to the determination of hydroquinone in the actual sample of industrial waste water.

  10. Economical benzene emission reduction

    International Nuclear Information System (INIS)

    Benzene has been classified as a toxic compound under the Canadian Environmental Protection Act. This has prompted the Alberta Energy and Utilities Board (AEUB) to introduce specific reporting and monitoring guidelines for the oil and gas industry regarding excessive benzene emissions. Glycol dehydration units have been determined to be the major single source of benzene emissions causing air and soil pollution. DualTank Corp. has designed a condensation and storage tank unit to enhance emission reduction, odour elimination and liquid recovery from dehydration units. Their newly designed combined tank unit consists of a large, uninsulated surface area for cooling, and an excessive internal volume for increased retention time. The first prototype was installed in December 1998 at an Enerplus Resources Site. The system provides excellent benzene emission reduction and the elimination of odours and visual plumes. Effective January 1, 1999, the petroleum and natural gas industry must either clean up excessive emissions voluntarily or face government imposed regulations, facility shutdowns and/or fines. 1 fig

  11. The impact of hydroquinone on acetylcholine esterase and certain human carbonic anhydrase isoenzymes (hCA I, II, IX, and XII).

    Science.gov (United States)

    Scozzafava, Andrea; Kalın, Pınar; Supuran, Claudiu T; Gülçin, İlhami; Alwasel, Saleh H

    2015-12-01

    Carbonic anhydrases (CAs) are widespread and the most studied members of a great family of metalloenzymes in higher vertebrates including humans. CAs were investigated for their inhibition of all of the catalytically active mammalian isozymes of the Zn(2+)-containing CA, (CA, EC 4.2.1.1). On the other hand, acetylcholinesterase (AChE. EC 3.1.1.7), a serine protease, is responsible for ACh hydrolysis and plays a fundamental role in impulse transmission by terminating the action of the neurotransmitter ACh at the cholinergic synapses and neuromuscular junction. In the present study, the inhibition effect of the hydroquinone (benzene-1,4-diol) on AChE activity was evaluated and effectively inhibited AChE with Ki of 1.22 nM. Also, hydroquinone strongly inhibited some human cytosolic CA isoenzymes (hCA I and II) and tumour-associated transmembrane isoforms (hCA IX, and XII), with Kis in the range between micromolar (415.81 μM) and nanomolar (706.79 nM). The best inhibition was observed in cytosolic CA II. PMID:25586344

  12. Purification and characterization of a tetrachloro-p-hydroquinone reductive dehalogenase from a Flavobacterium sp.

    OpenAIRE

    Xun, L; Topp, E.; Orser, C S

    1992-01-01

    Tetrachloro-p-hydroquinone (TeCH) is the first intermediate in pentachlorophenol (PCP) degradation by Flavobacterium sp. strain ATCC 39723. We previously purified a PCP hydroxylase that oxidized PCP to TeCH. Subsequently, we identified the reductive dehalogenation of TeCH to 2,3,6-trichloro-p-hydroquinone and then to 2,6-dichloro-p-hydroquinone in a cell extract with the reduced form of glutathione as the reducing agent under anaerobic conditions. Here we report the purification of a TeCH red...

  13. Carbo-quinoids: stability and reversible redox-proaromatic character towards carbo-benzenes.

    Science.gov (United States)

    Cocq, Kévin; Maraval, Valérie; Saffon-Merceron, Nathalie; Saquet, Alix; Poidevin, Corentin; Lepetit, Christine; Chauvin, Remi

    2015-02-23

    The carbo-mer of the para-quinodimethane core is stable within in a bis(9-fluorenylidene) derivative. Oxidation of this carbo-quinoid with MnO2 in the presence of SnCl2 and ethanol affords the corresponding p-bis(9-ethoxy-fluoren-9-yl)-carbo-benzene. The latter can be in turn converted back into the carbo-quinoid by reduction with SnCl2 , thus evidencing a chemical reversibility of the interconversion between a pro-aromatic carbo-quinoid and an aromatic carbo-benzene, and is reminiscent of the behavior of the benzoquinone/hydroquinone redox couple (in the red-ox opposite sense). PMID:25612252

  14. Comparative efficacy of 2% Hydroquinone and Melfade in Treatment of Melasma

    OpenAIRE

    R Yaghmaee; F Rad; F Farhadifar; M Najafi Pirasteh; Khatibi, R.

    2011-01-01

    Introduction & Objective: Melasma is an acquired hypermelanosis disease and can cause superficial problems in women if left untreated. The objective of this study was to compare the efficacy of 2% hydroquinone and Melfade in the treatment of Melasma. Materials & Methods: This is a randomized clinical trial study conducted at Kurdistan University of Medical Sciences in 2008. Sixty two women with Melasma disease were recruited and randomly assigned to two groups. Two percent hydroquinone wa...

  15. Benzene vapor recovery and processing

    International Nuclear Information System (INIS)

    The National Emissions Standards for Hazardous Air Pollutants, or NESHAPs, have provided a powerful motivation for interest in, and attention to, benzene vapor emissions in recent times. Benzene and its related aromatics are volatile organic compounds (VOCs), which marks them for surveillance as potential contributors to air pollution. In addition, benzene is a suspected carcinogen, which applies a special urgency to its control. The regulations governing the control of benzene emissions were issued as Title 40, Code of Federal Regulations, Part 61, subpart Y (Storage Vessels); subpart BB (Transfer Operations); and subpart FF (Waste Operations). These regulations specify very particular emission reduction guidelines for various generating sources. The problem in the hydrocarbon processing industry is to identify significant sources of benzene vapors in plants, and then to collect and process these vapors in an environmentally acceptable manner. This paper discusses various methods for collecting benzene fumes in these facilities

  16. Benzene exposures in urban areas

    International Nuclear Information System (INIS)

    Benzene exposures in urban areas were reviewed. Available data confirm that both in USA and Europe, benzene concentrations measured by fixed outdoor monitoring stations underestimate personal exposures of urban residents. Indoor sources, passive smoke and the high exposures during commuting time may explain this difference. Measures in European towns confirm that very frequently mean daily personal exposures to benzene exceed 10 μg/m3, current European air quality guideline for this carcinogenic compound

  17. Biomarkers of environmental benzene exposure.

    OpenAIRE

    Weisel, C; Yu, R; Roy, A; Georgopoulos, P.

    1996-01-01

    Environmental exposures to benzene result in increases in body burden that are reflected in various biomarkers of exposure, including benzene in exhaled breath, benzene in blood and urinary trans-trans-muconic acid and S-phenylmercapturic acid. A review of the literature indicates that these biomarkers can be used to distinguish populations with different levels of exposure (such as smokers from nonsmokers and occupationally exposed from environmentally exposed populations) and to determine d...

  18. Evaluation of in vivo mutagenicity of hydroquinone in Muta™ mice.

    Science.gov (United States)

    Matsumoto, Mariko; Masumori, Shoji; Hirata-Koizumi, Mutsuko; Ono, Atsushi; Honma, Masamitsu; Yokoyama, Kazuhito; Hirose, Akihiko

    2014-12-01

    Hydroquinone (HQ) is used in skin bleaching agents, hair dyes, and finger nail treatments. Many skin-lightening cosmetics that contain HQ are currently marketed in Japan. Concerns have been expressed regarding health risks to the general population because the carcinogenicity of HQ was previously suggested in animal studies. HQ induced hepatocellular adenomas and forestomach hyperplasias in mice and renal tubular cell adenomas in male rats. In the present study, the lacZ transgenic mutation assay was conducted according to OECD test guideline 488 to determine whether mutagenic mechanisms were involved in HQ-induced carcinogenesis. Male Muta™ mice were repeatedly administered HQ orally at dosages of 0, 25, 50, 100, or 200mg/kg bw/day for 28 days. Body weight gain was decreased in all treatment groups. No significant differences were observed in mutant frequencies in the liver, stomach, lung, or kidney between HQ-treated mice and the concurrent negative controls, whereas the significant induction of mutations was noted in the positive control, N-ethyl-N-nitrosourea. These results suggest that a mutagenic mechanism is not responsible for HQ-induced carcinogenesis. PMID:25435360

  19. Low-dose metabolism of benzene in humans: science and obfuscation.

    Science.gov (United States)

    Rappaport, Stephen M; Kim, Sungkyoon; Thomas, Reuben; Johnson, Brent A; Bois, Frederic Y; Kupper, Lawrence L

    2013-01-01

    Benzene is a ubiquitous air pollutant that causes human leukemia and hematotoxic effects. Although the mechanism by which benzene causes toxicity is unclear, metabolism is required. A series of articles by Kim et al. used air and biomonitoring data from workers in Tianjin, China, to investigate the dose-specific metabolism (DSM) of benzene over a wide range of air concentrations (0.03-88.9 p.p.m.). Kim et al. concluded that DSM of benzene is greatest at air concentrations American Petroleum Institute to fund a study by Price et al. to reanalyze the original data. Although their formal 'reanalysis' reproduced Kim's finding of enhanced DSM at sub-p.p.m. benzene concentrations, Price et al. argued that Kim's methods were inappropriate for assigning benzene exposures to low exposed subjects (based on measurements of urinary benzene) and for adjusting background levels of metabolites (based on median values from the 60 lowest exposed subjects). Price et al. then performed uncertainty analyses under alternative approaches, which led them to conclude that '… the Tianjin data appear to be too uncertain to support any conclusions …' regarding the DSM of benzene. They also argued that the apparent low-dose metabolism of benzene could be explained by 'lung clearance.' In addressing these criticisms, we show that the methods and arguments presented by Price et al. are scientifically unsound and that their results are unreliable. PMID:23222815

  20. Removal of benzene from wastewater via Fenton pre-treatment followed by enzyme catalyzed polymerization.

    Science.gov (United States)

    Saha, Beeta; Taylor, K E; Bewtra, J K; Biswas, N

    2011-01-01

    This study investigated the feasibility of a two-step process for the removal of benzene from buffered synthetic wastewater. Benzene is outside the scope of enzymatic removal. In order to remove it from wastewater using enzyme, its pretreatment by modified Fenton reaction was employed to generate the corresponding phenolic compounds. In the first phase, the optimum pH, H2O2 and Fe2+ concentrations and reaction time for the Fenton reaction were determined to maximize the conversion of benzene to phenolic compounds without causing significant mineralization. The pretreatment process was followed by oxidative polymerization of the phenolic compounds catalyzed by a laccase from Trametes villosa. Factors of interest for the three-hour enzymatic treatment were pH and laccase concentration. Under optimum Fenton reaction conditions, 80% conversion of the initial benzene concentration was achieved, giving a mixture containing oxidative dimerization product (biphenyl) and hydroxylation products (phenol, catechol, resorcinol, benzoquinone and hydroquinone). Enzymatic removal of biphenyl and benzoquinone was not possible but 2.5 U/mL laccase was successful in removal of the rest of the phenolic PMID:21866766

  1. Rate and capacity of hepatic microsomal ring-hydroxylation of phenol to hydroquinone and catechol in rainbow trout (Oncorhynchus mykiss).

    Science.gov (United States)

    Kolanczyk, Richard C; Schmieder, Patricia K

    2002-07-01

    Rainbow trout (Oncorhynchus mykiss) liver microsomes were used to study the rate of ring-hydroxylation of phenol at 11 and 25 degrees C by directly measuring the production of two potentially toxic metabolites, hydroquinone (HQ) and catechol (CAT). An HPLC method with integrated ultraviolet and electrochemical detection was used for metabolite identification and quantification at low (pmol) formation rates found in fish. The Michaelis-Menten saturation kinetics for the production of HQ and CAT over a range of phenol concentrations were determined at trout physiological pH. The apparent Km's for the production of HQ and CAT at 11 degrees C were 14+/-1 and 10+/-1 mM, respectively, with Vmax's of 552+/-71 and 161+/-15 pmol/min per mg protein. The kinetic parameters for HQ and CAT at 25 degrees C were 22+/-1 and 32+/-3 mM (Km) and 1752+/-175 and 940+/-73 pmol/min per mg protein (Vmax), respectively. The calculated increase in metabolic rate per 10 degrees C temperature rise (Q(10)) was 2.28 for HQ and 3.53 for CAT production. These experiments assess the potential for metabolic bioactivation in fish through direct quantification of putative reactive metabolites at the low, but toxicologically significant, chemical concentrations found in aquatic organisms. This work initiates a series of studies to compare activation pathway, rate, and capacity across fish species, providing a basis for development of biologically-based dose response models in diverse species. PMID:12062932

  2. Determination of Hydroquinone in a Square Wave Voltammetry based on Screen Printed Carbon Electrode

    Directory of Open Access Journals (Sweden)

    Alfita Safitri

    2015-01-01

    Full Text Available Hydroquinone is a phenolic compound are often used extensively in the cosmetics industry as whitening agent. This compound is very toxic and their use should be monitored. Due to the impact of hydroquinone, the use of hydroquinone restricted by BPOM (Food and Drug Regulatory Department in Indonesia maximum by 0.02%. The aim of this study was to establish a new simple sensitive voltammetry method for determination of hydroquinone using screen printed carbon electrode (spce. In this study, linear concentration range, limit of detection, sensitivity and accuracy were investigated. Before the determination of parameters analysis, the method require the optimization of method parameters such as frequency and pulse height. This study were showed that the measurement of hydroquinone with square wave voltammetry method has linear concentration range 1 - 100µM, limit of detection 23.4µM, sensitivity 0.075µM/µA and accuracy 0.9969. The proposed method was succesfully applied in whitening cream cosmetic samples with good enough results.

  3. Comparative metabolism of [14C]benzene to excretable products and bioactivation to DNA-binding derivatives in maternal and neonatal mice

    International Nuclear Information System (INIS)

    Lactating adult female mice treated with a single dose of 880 mg/kg i.p. [14C]benzene, and their 2-day-old sucklings similarly treated or nursed by their treated dams were compared in terms of their ability to metabolize benzene to urinary products or reactive intermediates as assessed by covalently-bound benzene derivatives in whole blood or liver DNA. Six metabolite fractions were identified in the urine of sucklings by high performance liquid chromatographic (HPLC) analysis at 5 h following intraperitoneal (direct) treatment with benzene. Three of the metabolite fractions co-chromatographed with authentic phenol, phenyl glucuronide, and muconic acid, and contributed 11, 6.9 and 0.6%, respectively, to the total urinary benzene metabolites. Two of the fractions were unidentified. The sixth and most polar fraction consisted of multiple metabolites, 21% of which were conjugates, and accounted for 72% of the total urinary metabolites. A similar metabolite profile was observed in 24-h urine samples from treated dams with the exception that one of the unidentified fractions in the sucklings was absent and levels of the metabolites were quantitatively higher than those observed in sucklings 5 h following their treatment with benzene. Furthermore, 78% of the most polar fraction from the dams consisted of conjugates compared with 21% of that from the sucklings. The metabolite pattern in urine of sucklings nursed by treated dams was qualitatively similar to, but quantitatively different from the pattern in treated dams. Five hours following intraperitoneal treatment with benzene, covalent binding of the compound to DNA (expressed as pmol benzene equivalents/mg DNA) in sucklings was slightly higher in whole blood (1.15±0.07) than in liver (0.77±0.07), whereas in the dam, it was slightly lower in whole blood (0.88±0.48) than in liver (1.63±0.61). Twenty four hours following benzene exposure in sucklings of benzene-treated dams, DNA binding by the compound in whole blood

  4. Vigna radiata as a New Source for Biotransformation of Hydroquinone to Arbutin

    Directory of Open Access Journals (Sweden)

    Zahra Tofighi, Mohsen Amini, Mahzad Shirzadi, Hamideh Mirhabibi, Negar Ghazi Saeedi, Narguess Yassa

    2016-06-01

    Full Text Available Background: The suspension culture of Vigna radiata was selected for biotransformation of hydroquinone to its β-D-glucoside form (arbutin as an important therapeutic and cosmetic compound. Methods: The biotransformation efficiency of a Vigna radiata cell culture in addition to different concentrations of hydroquinone (6-20 mg/100 ml was investigated after 24 hours in comparison to an Echinacea purpurea cell culture and attempts were made to increase the efficacy of the process by adding elicitors. Results: Arbutin was accumulated in cells and found in the media only in insignificant amounts. The arbutin content of the biomass extracts of V. radiata and E. purpurea was different, ranging from 0.78 to 1.89% and 2.00 to 3.55% of dry weight, respectively. V. radiata demonstrated a bioconversion efficiency of 55.82% after adding 8 mg/100 ml precursor, which was comparable with result of 69.53% for E. purpurea cells after adding 10 mg/100 ml hydroquinone (P>0.05. In both cultures, adding hydroquinone in two portions with a 24-hour interval increased the biotransformation efficiency. Different concentrations of methyl jasmonate (25, 50, and 100 µM and chitosan (50 and 100 µg/ml as elicitors increased the bio-efficiency percentage of the V. radiata culture in comparison with the flask containing only hydroquinone. Conclusion: This is the first report of the biotransformation possibility of V. radiata cultures. It was observed the bioconversion capacity increased by adding hydroquinone in two portions, which was comparable to adding an elicitor.

  5. Oxidation of benzene by the OH radical. A product and pulse radiolysis study in oxygenated aqueous solution

    International Nuclear Information System (INIS)

    Hydroxyl radicals have been reacted with benzene. The major product is phenol. At low dose rate (γ-radiolysis) it is formed in 53% yield with respect to the OH radical yield. This value increases to 93% in alkaline solution (pH 12.3). With deuteriated benzene it is reduced to 39%. In addition, more than fifteen different ring-opened and fragment products are formed. A good material balance (based on primary OH radical yield and oxygen consumption) was obtained. At high dose rate (pulse radiolysis) the major products are phenol, hydroquinone and cyclohexa-2,5-diene-1,4-diol. An important intermediate is the HO2./O2.-radical. Its rate of formation has been followed by us radiolysis using tetranitromethane as a scavenger as well as conductimetrically (build-up of H+/O2.-). The results have been interpreted. (Author)

  6. Electrochemical determination of hydroquinone using hydrophobic ionic liquid-type carbon paste electrodes

    Directory of Open Access Journals (Sweden)

    Liu Hongtao

    2010-10-01

    Full Text Available Abstract Three types of carbon paste electrodes (CPEs with different liquid binders were fabricated, and their electrochemical behavior was characterized via a potassium hexacyanoferrate(II probe. 1-Octyl-3-methylimidazolium hexafluorophosphate ionic liquid (IL as a hydrophobic conductive pasting binder showed better electrochemical performance compared with the commonly employed binder. The IL-contained CPEs demonstrated excellent electroactivity for oxidation of hydroquinone. A diffusion control mechanism was confirmed and the diffusion coefficient (D of 5.05 × 10-4 cm2 s-1 was obtained. The hydrophobic IL-CPE is promising for the determination of hydroquinone in terms of high sensitivity, easy operation, and good durability.

  7. Sorption of neptunium onto goethite in the presence of humic acids with different hydroquinone group content

    Energy Technology Data Exchange (ETDEWEB)

    Kalmykov, S.N.; Perminova, I.V.; Petrova (Khasanova), A.B.; Shcherbina, N.S. [Chemistry Dept., Lomonosov Moscow State Univ., Moscow (Russian Federation); Schaefer, T. [Forschungszentrum Karlsruhe, Inst. fuer Nukleare Entsorgung (INE), Karlsruhe (Germany); Claret, F. [CEA Saclay, CEA/DPC/SECR/LSRM, Gif-sur-Yvette (France); Teterin, Y.A. [Scientific Centre ' ' Kurchatov Inst.' ' , Moscow (Russian Federation)

    2008-07-01

    Neptunyl sorption in the ternary system of goethite-humic acid (HA)-Np was studied in a series of batch experiments with natural leonardite HA and a hydroquinone enriched derivative. The reduction of Np(V) at low pH has been observed by XPS upon interaction with hydroquinone-enriched leonardite HA-goethite suspension. Under these low pH conditions the formation of humate coatings at the goethite mineral surface has been identified using scanning transmission X-ray microscopy (STXM) at the carbon K-edge. (orig.)

  8. 2,3,5-Trimethyl-1,4-hydroquinone

    Directory of Open Access Journals (Sweden)

    Jun Dai

    2010-02-01

    Full Text Available The molecule of the title compound, C9H12O2, is approximately planar (mean atomic deviation = 0.0346 Å and disposed about a crystallographic centre of symmetry. The H atom of the benzene ring is disordered over four orientations, with occupancies of 0.100 (3 and 0.401 (3 at the C atoms in the 2- and 3-positions and the same at their symmetric location. The H atoms of methyl group at the 2-position are disordered over two positions of equal occupancy. In the crystal structure, adjacent molecules are linked through O—H...O hydrogen bonds, forming a two-dimensional network.

  9. Ocronose exógena induzida por hidroquinona: relato de quatro casos Exogenous ochronosis hydroquinone induced: a report of four cases

    Directory of Open Access Journals (Sweden)

    Jonas Ribas

    2010-10-01

    Full Text Available A ocronose exógena é uma dermatose, aparentemente pouco frequente, caracterizada por hiperpigmentação negro-azulada fuliginosa, localizada na região onde foi aplicado o agente causador. Pode ser causada por uso de medicamentos sistêmicos, os antimaláricos e de uso tópico, como fenol, resorcinol, benzeno, ácido pícrico e a hidroquinona - que é um composto fenólico, com propriedade despigmentante, muito utilizado em formulações dermatológicas para o tratamento de melasma e outras hiperpigmentações. A fisiopatogenia deste processo ainda não está esclarecida e as abordagens terapêuticas são insatisfatórias. Relatam-se quatro casos de pacientes do sexo feminino que, após uso de preparados contendo hidroquinona, desenvolveram hiperpigmentação acentuada na face, caracterizadas no exame dermatológico e histopatológico como ocronose. Enfatiza-se a possibilidade de casos de ocronose exógena estarem sendo diagnosticados erroneamente, como falha de tratamento de melasma, e também para os riscos do uso indiscriminado de formulações, contendo hidroquinona, muitas vezes, sem acompanhamento médico.Exogenous ochronosis is an infrequent dermatosis characterized as a dark blue hyperpigmentation localized where the causing agent was applied. It may be caused by the use of systemic medication such as antimalarials and by the use of topic substances such as phenol, resorcinol, benzene, or hydroquinone, which is a fenolic compound with depigmentation action, largely used in the treatment of melasma and other hyperpigmentation. The physiopathology of this process is not well clear up to this moment, and the therapeutic measures are not satisfactory either. Here we present four cases of female patients that developed hyperpigmentation on their faces after the use of hydroquinone containing compounds, characterized clinically and histological as ochronosi. We emphasize the possibility of exogenous ochronosis cases being misdiagnosed as a

  10. HPLC-UV Method for the Identification and Screening of Hydroquinone, Ethers of Hydroquinone and Corticosteroids Possibly Used as Skin-Whitening Agents in Illicit Cosmetic Products.

    Science.gov (United States)

    Gimeno, Pascal; Maggio, Annie-Françoise; Bancilhon, Marjorie; Lassu, Nelly; Gornes, Hervé; Brenier, Charlotte; Lempereur, Laurent

    2016-03-01

    Corticosteroids, hydroquinone and its ethers are regulated in cosmetics by the Regulation 1223/2009. As corticosteroids are forbidden to be used in cosmetics and cannot be present as contaminants or impurities, an identification of one of these illicit compounds deliberately introduced in these types of cosmetics is enough for market survey control. In order to quickly identify skin-whitening agents present in illegal cosmetics, this article proposes an HPLC-UV method for the identification and screening of hydroquinone, 3 ethers of hydroquinone and 39 corticosteroids that may be found in skin-whitening products. Two elution gradients were developed to separate all compounds. The main solvent gradient (A) allows the separation of 39 compounds among the 43 compounds considered in 50 min. Limits of detection on skin-whitening cosmetics are given. For compounds not separated, a complementary gradient elution (B) using the same solvents is proposed. Between 2004 and 2009, a market survey on "skin-whitening cosmetic" was performed on 150 samples and highlights that more than half of the products tested do not comply with the Cosmetic Regulation 1223/2009 (amending the Council Directive 76/768/EEC). PMID:26462503

  11. Hydroquinone-induced exogenous ochronosis: a report of four cases and usefulness of dermoscopy.

    Science.gov (United States)

    Charlín, Raúl; Barcaui, Carlos B; Kac, Bernard Kawa; Soares, Deborah Brazuna; Rabello-Fonseca, Rosa; Azulay-Abulafia, Luna

    2008-01-01

    Hydroquinone is the first choice of topical bleaching agents used in treatment of melasma. In Brazil, hydroquinone is widely prescribed by physicians and often used by patients without a prescription. The principal adverse effects of its chronic use are confetti-like depigmentation and exogenous ochronosis. The latter manifests clinically with gray-brown or blue-black hyperpigmentation, as well as pinpoint hyperchromic papules that look like caviar, and therefore called caviar-like. On histopathology, curved ochre-colored structures, 'banana-shaped' fibers, appear in the papillary dermis. No description of dermoscopy in ochronosis is found in the literature. We report four cases of hydroquinone-induced exogenous ochronosis. Dermoscopy was performed in two patients on the areas with ochronosis, and in addition to the melasma findings, amorphous densely pigmented structures obliterating some follicular openings were observed. Exogenous ochronosis is an avoidable dermatosis that is difficult to treat. Dermatologists should be able to differentiate it from melasma and immediately discontinue hydroquinone. Dermoscopy might become a valuable resource in approaching exogenous ochronosis. PMID:18173595

  12. Reduction of actinides in higher oxidation states by hydroquinone-enriched humic derivatives

    International Nuclear Information System (INIS)

    Natural humic materials are known to cause a reduction of penta- and hexavalent plutonium; however, contradicting results have been previously reported for neptunium. The goal of this study was to determine if incorporation of additional reducing centers into humic structure would yield material with enhanced reducing performance with respect to higher valent actinides, nominally, Pu(V) and Np(V). Hydroquinone-moieties were used as the redox centers. They were incorporated into humic structures using formaldehyde condensation at different monomer-to-humic ratios to obtain materials of different reducing properties. Reduction of model actinides by the hydroquinone-enriched humic materials was studied under both oxic and anoxic conditions at acidic and neutral pH values. Redox speciation of plutonium and neptunium was monitored using solvent extraction techniques and liquid scintillation counting. It was shown that both nonmodified leonardite humic acid and all the obtained derivatives were able to reduce Pu(V) quantitatively both at neutral and acidic pH and under oxic and anoxic conditions. The reduction rate increased with an increase in the degree of modification of the humic material and reached its maximum for HQ500 derivative. For neptunium, reduction was observed only under anoxic conditions at acidic pH. The hydroquinone-modified derivatives had much higher reducing performance when compared to nonmodified leonardite humic acid. The results obtained show good prospects for a use of hydroquinone-modified humic materials as reactive agents for remediation of actinide contaminated aquifers

  13. Reduction of actinides in higher oxidation states by hydroquinone-enriched humic derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Shcherbina, N.S. [Vernadsky Institute of Geochemistry and Analytical Chemistry, Laboratory of Radiochemistry, Moscow 119991 (Russian Federation)], E-mail: sher@radio.chem.msu.ru; Kalmykov, St.N.; Perminova, I.V.; Kovalenko, A.N. [Department of Chemistry, Lomonosov Moscow State University, Moscow 119992 (Russian Federation)

    2007-10-11

    Natural humic materials are known to cause a reduction of penta- and hexavalent plutonium; however, contradicting results have been previously reported for neptunium. The goal of this study was to determine if incorporation of additional reducing centers into humic structure would yield material with enhanced reducing performance with respect to higher valent actinides, nominally, Pu(V) and Np(V). Hydroquinone-moieties were used as the redox centers. They were incorporated into humic structures using formaldehyde condensation at different monomer-to-humic ratios to obtain materials of different reducing properties. Reduction of model actinides by the hydroquinone-enriched humic materials was studied under both oxic and anoxic conditions at acidic and neutral pH values. Redox speciation of plutonium and neptunium was monitored using solvent extraction techniques and liquid scintillation counting. It was shown that both nonmodified leonardite humic acid and all the obtained derivatives were able to reduce Pu(V) quantitatively both at neutral and acidic pH and under oxic and anoxic conditions. The reduction rate increased with an increase in the degree of modification of the humic material and reached its maximum for HQ500 derivative. For neptunium, reduction was observed only under anoxic conditions at acidic pH. The hydroquinone-modified derivatives had much higher reducing performance when compared to nonmodified leonardite humic acid. The results obtained show good prospects for a use of hydroquinone-modified humic materials as reactive agents for remediation of actinide contaminated aquifers.

  14. Quantitative Determination of Arbutin and Hydroquinone in Different Plant Materials by HPLC

    Directory of Open Access Journals (Sweden)

    Izabela RYCHLINSKA

    2012-11-01

    Full Text Available A simple, fast method of high-performance liquid chromatography for the determination and quantification of arbutin and hydroquinone in many different raw materials was developed and validated. The optimum conditions for the separation and detection of these two constituents were achieved on a LiChro-CARD 125-4 Superspher®100 RP-18 column with the water-methanol (gradient elution mobile phase and recorded at 289 nm. The purities of peaks were verified by PDA analysis of impurities. The results of validation have shown that the HPLC method is stable and accurate for the simultaneous determination of arbutin and hydroquinone in extracts from various plants. The developed method gave a good sensitivity (LOD 1µg/ml for arbutin and 0.49 µg/ml for hydroquinone with linearity R2 >0.9993 (for both. The relative standard deviation of the method was less than 2.53% for intra-day assays and 3.23% for inter-day assay, the accuracy of the recovery test ranged from 98.96% to 106.4%. This method was used in comparative qualitative analysis of arbutin and hydroquinone in 16 different raw materials from families Lamiaceae, Ericacaeae, Saxifragaceae, Rosaceae. The content of arbutin in B. ciliata, B. cordifolia and Ledum palustre was examined for the first time.

  15. Adsorptive Stripping Voltammetric Determination of Hydroquinone using an Electrochemically Pretreated Glassy Carbon Electrode

    Directory of Open Access Journals (Sweden)

    Abdul Niaz1,

    2008-12-01

    Full Text Available A simple and efficient adsorptive stripping voltammetric (AdSV method was developed for the determination of hydroquinone at an electrochemically pretreated glassy carbon (GC electrode in waste water. Various parameters such as solvent system, accumulation potential, accumulation time and scan rate were optimized. The electrochemically pretreated GC electrode showed good response towards hydroquinone determination by using AdSV. Under the optimized conditions the peak current showed good linear relationship with the hydroquinone concentration in the range of 0.5-4.0mg L-1 and 5-30mg L-1. The 60/40 methanol/water composition was found to be the best solvent system and 0.05mol L-1 H2SO4 was found as useful supporting electrolyte concentration. The accumulation time was 60 s and the detection limit was 50µg L-1. The developed method was successfully applied for the determination of hydroquinone in polymeric industrial discharge samples waste photographic developer solution and cream sample without any significant effect of surface fouling.

  16. Anticancer activity of botanical alkyl hydroquinones attributed to topoisomerase II poisoning

    International Nuclear Information System (INIS)

    Cytotoxic alkyl hydroquinone compounds have been isolated from many plants. We previously isolated 3 structurally similar cytotoxic alkyl hydroquinone compounds from the sap of the lacquer tree Rhus succedanea L. belonging to the sumac family, which have a long history of medicinal use in Asia. Each has an unsaturated alkyl chain attached to the 2-position of a hydroquinone ring. One of these isolates, 10'(Z),13'(E),15'(E)-heptadecatrienylhydroquinone [HQ17(3)], being the most cytotoxic, was chosen for studying the anticancer mechanism of these compounds. We found that HQ17(3) was a topoisomerase (Topo) II poison. It irreversibly inhibited Topo IIα activity through the accumulation of Topo II-DNA cleavable complexes. A cell-based assay showed that HQ17(3) inhibited the growth of leukemia HL-60 cells with an EC50 of 0.9 μM, inhibited the topoisomerase-II-deficient cells HL-60/MX2 with an EC50 of 9.6 μM, and exerted no effect on peripheral blood mononuclear cells at concentrations up to 50 μM. These results suggest that Topo II is the cellular drug target. In HL-60 cells, HQ17(3) promptly inhibited DNA synthesis, induced chromosomal breakage, and led to cell death with an EC50 about one-tenth that of hydroquinone. Pretreatment of the cells with N-acetylcysteine could not attenuate the cytotoxicity and DNA damage induced by HQ17(3). However, N-acetylcysteine did significantly reduce the cytotoxicity of hydroquinone. In F344 rats, intraperitoneal injection of HQ17(3) for 28 days induced no clinical signs of toxicity. These results indicated that HQ17(3) is a potential anticancer agent, and its structural features could be a model for anticancer drug design

  17. Separate and combined effect of low doses of ionizing radiation and hydroquinone on humoral immune response in regional lymph nodes

    International Nuclear Information System (INIS)

    The whole-body exposure of mice to 0.1 Gy γ-radiation resulted in stimulation of T-cell dependent humoral immune response in lymph nodes. At the same enhansement of succeptability of immunocompetent cells to damaging effect of hydroquinone was observed. Under irradiation with doses of 0.5 or 1 Gy which cause dose-dependent immunosupression, hydroquinone induced stimulation of antigene production

  18. Species differences in the metabolism of benzene.

    OpenAIRE

    Henderson, R F

    1996-01-01

    The pathways of metabolism of benzene appear to be qualitatively similar in all species studied thus far. However, there are quantitative differences in the fraction of benzene metabolized by the different pathways. These species differences become important for risk assessments based on animal data. Mice have a greater overall capacity to metabolize benzene than rats or primates, based on mass balance studies conducted in vivo using radiolabled benzene. Mice and monkeys metabolize more of th...

  19. Kinetic and thermodynamic properties of the aerial oxidation of hydroquinone in developer solutions

    Institute of Scientific and Technical Information of China (English)

    NASEHZADEH, Asadollah; RESA, Sayyed Hossain; KHOSRAVAN, Azita

    2000-01-01

    The aerial oxidation kinetics of hydroquinone in a freshly prepared developer solution at different temperatures and pHs has been studied. The activation parameters, Ea, △G#,△S# , △H# and enthalpy of formation of activated complex,△Hof(X# ), are determined. The large negative value of free energy of activation △G# proves that hydroquinone extremely tends to be oxidized by air at optimum temperature (20℃)and optimum pH (10.5) and converts to the activated complex semiquinone. It was also found that if the pH of the developer solution is increased from 9.3 to 10.5 the reaction rate will increase by a factor of 2.

  20. 27 CFR 21.97 - Benzene.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Benzene. 21.97 Section 21... TREASURY LIQUORS FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants § 21.97 Benzene. (a..., Standard No. D 836-77; for incorporation by reference, see § 21.6(b).) When 100 ml of benzene are...

  1. Electrochemical determination of hydroquinone using hydrophobic ionic liquid-type carbon paste electrodes

    OpenAIRE

    Liu Hongtao; Tang Yougen; She Yiyi; He Ping

    2010-01-01

    Abstract Three types of carbon paste electrodes (CPEs) with different liquid binders were fabricated, and their electrochemical behavior was characterized via a potassium hexacyanoferrate(II) probe. 1-Octyl-3-methylimidazolium hexafluorophosphate ionic liquid (IL) as a hydrophobic conductive pasting binder showed better electrochemical performance compared with the commonly employed binder. The IL-contained CPEs demonstrated excellent electroactivity for oxidation of hydroquinone. A diffusion...

  2. Nitration of phenolic compounds and oxidation of hydroquinones using tetrabutylammonium chromate and dichromate under aprotic conditions

    Indian Academy of Sciences (India)

    Ali Reza Pourali; Arezou Goli

    2011-01-01

    In this work, we have reported a mild, efficient and selective method for the mononitration of phenolic compounds using sodium nitrite in the presence of tetrabutylammonium dichromate (TBAD) and oxidation of hydroquinones to quinones with TBAD in CH2Cl2. Using this method, high yields of nitrophenols and quinones were obtained under neutral aprotic conditions. Tetrabutylammonium chromate (TBAC) can also be used as oxidant at same conditions.

  3. Stability of the Hsp90 inhibitor 17AAG hydroquinone and prevention of metal-catalyzed oxidation

    OpenAIRE

    Guo, Wenchang; Siegel, David; Ross, David

    2008-01-01

    17-(allylamino)-17-demethoxygeldanamycin (17AAG) is a benzoquinone ansamycin Hsp90 inhibitor which has promising anticancer activity in vitro, in animal models and in clinical trials. 17AAG has poor water-solubility which is a potential problem for clinical formulation. The hydroquinone derivative of 17AAG, 17AAGH2, is considerably more water soluble and since we previously demonstrated that 17AAGH2 was a more potent Hsp90 inhibitor than its parent quinone, it is a good candidate for clinical...

  4. Volatile Metabolites

    Directory of Open Access Journals (Sweden)

    Daryl D. Rowan

    2011-11-01

    Full Text Available Volatile organic compounds (volatiles comprise a chemically diverse class of low molecular weight organic compounds having an appreciable vapor pressure under ambient conditions. Volatiles produced by plants attract pollinators and seed dispersers, and provide defense against pests and pathogens. For insects, volatiles may act as pheromones directing social behavior or as cues for finding hosts or prey. For humans, volatiles are important as flavorants and as possible disease biomarkers. The marine environment is also a major source of halogenated and sulfur-containing volatiles which participate in the global cycling of these elements. While volatile analysis commonly measures a rather restricted set of analytes, the diverse and extreme physical properties of volatiles provide unique analytical challenges. Volatiles constitute only a small proportion of the total number of metabolites produced by living organisms, however, because of their roles as signaling molecules (semiochemicals both within and between organisms, accurately measuring and determining the roles of these compounds is crucial to an integrated understanding of living systems. This review summarizes recent developments in volatile research from a metabolomics perspective with a focus on the role of recent technical innovation in developing new areas of volatile research and expanding the range of ecological interactions which may be mediated by volatile organic metabolites.

  5. Mercury, hydroquinone and clobetasol propionate in skin lightening products in West Africa and Canada.

    Science.gov (United States)

    Gbetoh, Mètogbé Honoré; Amyot, Marc

    2016-10-01

    Skin lightening products are types of cosmetics (creams, gels, lotions and soaps) applied voluntarily on skin. Several of these products contain a variety of active ingredients that are highly toxic. Among those toxic agents, the present study focuses on mercury, hydroquinone, and clobetasol propionate. Out of the 93 lightening soaps and 98 creams purchased in large city markets in sub-Saharan West Africa and in small ethnic shops in Canada, 68-84% of all creams and 7.5-65% of all soaps exceeded regulatory guidelines for at least one active ingredient when considering different regulations. Mercury was found in high concentrations mainly in soaps, while hydroquinone and clobetasol propionate concentrations exceeded US FDA standards in some creams for all countries included in our study. Concentrations of the three compounds declared on labels of soaps and creams usually did not correspond to concentrations actually measured, particularly for mercury and hydroquinone. Overall, our results indicate that most studied skin-lightening products are potentially toxic and that product labels are frequently inaccurate with respect to the presence of toxic agents. PMID:27372064

  6. Comparative efficacy of 2% Hydroquinone and Melfade in Treatment of Melasma

    Directory of Open Access Journals (Sweden)

    R Yaghmaee

    2011-04-01

    Full Text Available Introduction & Objective: Melasma is an acquired hypermelanosis disease and can cause superficial problems in women if left untreated. The objective of this study was to compare the efficacy of 2% hydroquinone and Melfade in the treatment of Melasma. Materials & Methods: This is a randomized clinical trial study conducted at Kurdistan University of Medical Sciences in 2008. Sixty two women with Melasma disease were recruited and randomly assigned to two groups. Two percent hydroquinone was prescribed for the first group (n=31 and Melfade for the second group. After 12 weeks of daily drug consumption by the patients, they were examined by a dermatologist for assessment of recovery. The collected data was analyzed by the SPSS software. Results: Response to treatment with hydroquinone and Melfade- was the same and no significant differences were found between the two groups. (P>0.05 onclusion: Results of this study demonstrated that topical Melfade is as effective as 2% hydrquinone in treatment of Melasma, Therefore it can be considered as an alternative drug in the treatment of Melasma.

  7. Polyaniline/polysulfone composite film electrode for simultaneous determination of hydroquinone and catechol

    International Nuclear Information System (INIS)

    Highlights: ► We prepared a composite film which has bi-layers with asymmetric microstructure and relatively rich porosity which provides larger surface area for electrochemical reaction. ► The outer polysulfone layer is propitious for the organic molecules to enrich on the composite film, which brings great enhancement in electron transfer kinetics. ► The composite film electrode can be used to detect qualitatively or quantitatively hydroquinone and catechol in the single solute or mixed systems. - Abstract: Polyaniline (PAN)/polysulfone (PSF) composite film electrodes were successfully prepared by electropolymerization using cyclic votammetry technique. The composite film electrodes show a great enhancement in electron transfer kinetics, and the separation between oxidation and reduction peaks (ΔEp) decreases from 200 to 35 mV for hydroquinone (H2Q) and from 275 to 42 mV for catechol (CC) at bare Pt and composite film electrodes respectively. In their mixed systems, the redox peak of H2Q and two pairs of redox peaks of CC on this composite film electrode could be obviously distinguished which indicates the composite film electrodes have excellent electrocatalytic activity and reversibility towards the oxidation of two diphenols (hydroquinone and catechol). The linear relationships between the peak current and concentration are observed for single solute and mixed systems within the certain concentration range, implying that the composite film electrodes have potential application in the qualitative or quantitative analysis of diphenol.

  8. EPR study of gamma irradiated 2,5-di-tert-butyl-hydroquinone single crystals

    International Nuclear Information System (INIS)

    γ-irradiated single crystals of 2,5-di-tert-butyl-hydroquinone (DTBHQ) were investigated using the electron paramagnetic resonance (EPR) technique. The spectra of the crystals at different orientations in the magnetic field between temperatures of 120 and 450 K, were found to be temperature dependent. Taking into consideration the chemical structure and the experimental spectra of the irradiated single crystals of DTBHQ, we assumed that one or more paramagnetic species were produced, each having an unpaired electron delocalized in the phenyl ring. Pursuant to this assumption, four possible radicals were modeled using the B3LYP/6-31+G(d) level of density-functional theory. EPR parameters were calculated for these modeled radicals using the B3LYP method and TZVP basis set. The calculated hyperfine-coupling constants were used as starting points for simulations. The experimental and simulated spectra for each of the three crystallographic axes were well matched for the modeled radical R4; we thus identified the hydroquinone anion radical as a paramagnetic species produced in DTBHQ. The experimental g-factor of the hydroquinone anion radical were found to be anisotropic with the average value giso=2.0096. The hyperfine coupling constants of the Ηα proton was found anisotropic with the average value (aH7α)iso=6.3G and Ηβ proton was found isotropic with the average value (aH8β)=3.5G.

  9. Molecular Orientation of Hydroquinone Adsorbed at a Platinum(111) Thin-Layer Electrode.

    Science.gov (United States)

    Ren; Hubbard

    1999-01-15

    Reported are new findings regarding the molecular orientation of hydroquinone (HQ) adsorbed on Pt surfaces. The packing density of hydroquinone adsorbed from 1 M HClO4 supporting electrolyte has been measured by use of a Pt(111) thin-layer electrode. The packing-density-vs-concentration profiles for hydroquinone, measured by a differential thin-layer electrode method at an ordered Pt(111) surface and at an electrochemically disordered Pt(111) surface, are identical within an experimental error of about 8%. The profiles from this study are similar to the ones obtained previously at an ordered Pt(111) surface by Auger spectroscopy, but they are significantly different from those reported previously for polycrystalline Pt thin-layer electrodes. A procedure based upon displacement of HQ by thiocyanate has been developed as an alternative method for determining the packing density of adsorbed HQ. Both methods afford information regarding the molecular state of HQ adsorbed at the Pt(111) surface. Copyright 1999 Academic Press. PMID:9885274

  10. Brain met-enkephalin immunostaining after subacute and subchronic exposure to benzene

    Energy Technology Data Exchange (ETDEWEB)

    Gandarias, J.M. de; Echevarria, E.; Martinez-Millan, L.; Casis, L. [Univ. of the Basque Country, Bilbao (Spain); Martinez-Garcia, F. [Univ. of Valencia (Spain)

    1994-01-01

    Benzene is used in a wide variety of domestic and occupational activities, and due to its lipophilic nature, it accumulates in lipid-rich tissues like the brain. In this sense, neurotoxic action has long been associated with organic solvent exposure and it has been shown that benzene, injected in a single dose or during a prolongued administration, modifies the content of dopamine, noradrenaline, serotonin and its main metabolite 5-hydroxy indolacetic acid, in several brain regions of the rat, then revealing a stimulating action on brain monoamine synthesis and turnover. However, information concerning neurotoxic action of benzene exposure in vivo on peptidergic neuromodulatory systems is still lacking. Nevertheless, it has been recently described that subacute benzene exposure in rats generates regional changes in brain aminopeptidase activity. These proteolytic enzymes have been widely associated with metabolic control of neuropeptides and it has been suggested that they could play a role in benzene neurotoxic mechanism by hypothetically changing regional neuropeptide levels. This being the case, we focused on analyzing met-enkephalin immunostaining in different brain regions of the rat after subacute and subchronic administration of benzene. 12 refs., 3 figs.

  11. 46 CFR 151.05-2 - Compliance with requirements for tank barges carrying benzene and benzene containing cargoes, or...

    Science.gov (United States)

    2010-10-01

    ... benzene and benzene containing cargoes, or butyl acrylate cargoes. 151.05-2 Section 151.05-2 Shipping... Compliance with requirements for tank barges carrying benzene and benzene containing cargoes, or butyl acrylate cargoes. A tank barge certificated to carry benzene and benzene containing cargoes or...

  12. Secondary Metabolites from Three Florida Sponges with Antidepressant Activity

    Science.gov (United States)

    Kochanowska, Anna J.; Rao, Karumanchi V.; Childress, Suzanne; El-Alfy, Abir; Matsumoto, Rae R.; Kelly, Michelle; Stewart, Gina S.; Sufka, Kenneth J.; Hamann, Mark T.

    2016-01-01

    Brominated indole alkaloids are a common class of metabolites reported from sponges of the order Verongida. Herein we report the isolation, structure determination, and activity of metabolites from three Florida sponges, namely, Verongula rigida (order Verongida, family Aplysinidae), Smenospongia aurea, and S. cerebriformis (order Dictyoceratida, family Thorectidae). All three species were investigated chemically, revealing similarities in secondary metabolites. Brominated compounds, as well as sesquiterpene quinones and hydroquinones, were identified from both V. rigida and S. aurea despite their apparent taxonomic differences at the ordinal level. Similar metabolites found in these distinct sponge species of two different genera provide evidence for a microbial origin of the metabolites. Isolated compounds were evaluated in the Porsolt forced swim test (FST) and the chick anxiety–depression continuum model. Among the isolated compounds, 5,6-dibromo-N,N-dimethyltryptamine (1) exhibited significant antidepressant-like action in the rodent FST model, while 5-bromo-N,N-dimethyltryptamine (2) caused significant reduction of locomotor activity indicative of a potential sedative action. The current study provides ample evidence that marine natural products with the diversity of brominated marine alkaloids will provide potential leads for antidepressant and anxiolytic drugs. PMID:18217716

  13. Double photoionization of halogenated benzene

    International Nuclear Information System (INIS)

    We have experimentally investigated the double-photoionization process in C6BrF5 using monochromatized synchrotron radiation. We compare our results with previously published data for partially deuterated benzene (C6H3D3) over a wide range of photon energies from threshold to 270 eV. A broad resonance in the ratio of doubly to singly charged parent ions at about 65 eV appears shifted in energy compared to benzene data. This shift is due to the difference in the bond lengths in two molecules. A simple model can explain the shape of this resonance. At higher photon energies, we observe another broad resonance that can be explained as a second harmonic of the first resonance

  14. Double photoionization of halogenated benzene

    Energy Technology Data Exchange (ETDEWEB)

    AlKhaldi, Mashaal Q. [Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstr. 36, D-10623 Berlin (Germany); Wehlitz, Ralf, E-mail: rwehlitz@gmail.com [Synchrotron Radiation Center, University of Wisconsin–Madison, Stoughton, Wisconsin 53589 (United States)

    2016-01-28

    We have experimentally investigated the double-photoionization process in C{sub 6}BrF{sub 5} using monochromatized synchrotron radiation. We compare our results with previously published data for partially deuterated benzene (C{sub 6}H{sub 3}D{sub 3}) over a wide range of photon energies from threshold to 270 eV. A broad resonance in the ratio of doubly to singly charged parent ions at about 65 eV appears shifted in energy compared to benzene data. This shift is due to the difference in the bond lengths in two molecules. A simple model can explain the shape of this resonance. At higher photon energies, we observe another broad resonance that can be explained as a second harmonic of the first resonance.

  15. Slow Neutron Scattering by Benzene

    International Nuclear Information System (INIS)

    We have calculated the scattering of slow neutrons by the benzene molecule. The calculations are carried out within the framework of the time dependent formalism of Zemach and Glauber. Detailed account is taken of the effects of the molecular vibrations on the neutron scattering. Among the results explicitly calculated are the slow neutron total scattering cross-section as a function of energy and the energy angular distribution of singly scattered sections. (author)

  16. Risk estimation of benzene-induced leukemia by radiation equivalent dose

    International Nuclear Information System (INIS)

    Based on the Hiroshima and Nagasaki epidemiological study, risk assessment system for radiation has been well developed and is practically applied to the international protection standards. Hence, defining the radiation equivalent dose for chemical agents could place in the order of their risk. As well as the radiation, benzene causes leukemia to humans. Therefore, we evaluated the radiation-equivalent dose for benzene based on chromosome aberration rates induced by its metabolites and low-dose rate radiation because chromosome aberration is thought to be closely related to the leukemogenesis. Using radiation risk coefficient, the leukemia risk caused by 1 mg/m3 benzene inhalation was estimated 5.5 - 7.3 x 10-8, which is underestimated compared to other studies based on human epidemiological researches. (author)

  17. Co-drug strategy for promoting skin targeting and minimizing the transdermal diffusion of hydroquinone and tranexamic acid.

    Science.gov (United States)

    Hsieh, Pei-Wen; Chen, Wei-Yu; Aljuffali, Ibrahim A; Chen, Chun-Che; Fang, Jia-You

    2013-01-01

    Hydroquinone and tranexamic acids (TXA) are skin-lightening agents with a hydrophilic nature and low skin absorption. A high dose is needed for clinical use, resulting in a high incidence of skin irritation. Co-drugs formed by conjugating hydroquinone and TXA were synthesized and their in vitro and in vivo skin absorption characteristics were evaluated. The two synthesized co-drugs were 4-hydroxyphenyl 4-(aminomethyl)cyclohexanecarboxylate (HAC) and 1,4- phenylene bis(aminomethyl)cyclohexanecarboxylate (BAC). The co-drugs were chemically stable in aqueous solution, but rapidly degraded to the respective parent drug in esterases and skin homogenates. Compared to hydroquinone application, 7.2- and 2.4-fold increments in the hydroquinone skin deposition were obtained with the in vitro application of HAC and BAC. HAC and BAC led to 3- and 2-fold enhancements of equivalent TXA deposition compared to TXA administration. The in vivo experiment showed a further enhancement of co-drugs compared to the in vitro setup. The transdermal penetration of co-drugs, especially BAC, was much lower than that of hydroquinone and TXA. This indicated high-level skin targeting by the co-drugs. HAC and BAC revealed strong affinities for the viable epidermis/dermis. Hair follicles are important reservoirs for co-drug delivery. Daily administration of co-drugs to the skin did not generate irritation for up to 7 days. Both co-drugs are superior candidates for treating skin hyperpigmentation. PMID:23931279

  18. Electrochemical behaviour of benzene on platinum electrodes

    OpenAIRE

    Montilla Jiménez, Francisco; Huerta Arráez, Francisco; Morallón Núñez, Emilia; Vázquez Picó, José Luis

    1999-01-01

    The adsorption and oxidation of benzene in acidic media on platinum electrodes (polycrystalline and single-crystal electrodes) have been studied by cyclic voltammetry and in-situ Fourier transform infrared spectroscopy. The oxidation characteristics of benzene depend on the surface structure of the platinum electrode used. In all platinum electrodes studied, the main reduction product of benzene is cyclohexane, and the oxidation products detected by infrared spectroscopy have been CO2 and ben...

  19. Construction of a Homonaphthazarin Skeleton and Synthesis of Hydroquinone-annelated Cycloheptatriene Derivatives

    OpenAIRE

    ŞENGÜL, M. Emin; BALCI, Abdullah MENZEK and Metin

    2006-01-01

    1,4-Dihydroxy-7,8-dihydro-5H-benzo[a]cycloheptene-5,9(6H)- dione (7) was synthesised from hydroquinone and glutaric acid chloride via an acylation reaction. The reaction of dione (7) with bromine followed by treatment with NEt3 gave homonaphthazarin 8 as well as the brominated derivatives 9 and 10. Reduction of 1,4-dimethoxy-7,8-dihydro-5H-benzo[a]cycloheptene-5,9(6H)-dione (16) with LiAlH4 gave 2 isomeric alcohols, 17 and 18. Reaction of these alcohols with SOCl2 followed by HCl el...

  20. Electrocatalytic determination of epinephrine and uric acid using a novel hydroquinone modified carbon paste electrode

    Institute of Scientific and Technical Information of China (English)

    Mohammad Mazloum-Ardakani; Zahra Taleat; Hadi Beitollahi; Hossein Naeimi

    2011-01-01

    A sensitive and selective electrochemical method for the determination of epinephrine (EP) was developed using a modified carbon paste electrode (MCPE) with 2,2'- [3,6-dioxa-l,8-octanediylbis(nitriloethylidyne)]-bis-hydroquinone (DOH). Cyclic vol-tammetry was used to investigate the redox properties of this modified electrode at various solution pH values and at various scan rates. In differential pulse voltammetry, the modified electrode could separate the oxidation peak potentials of EP and uric acid (UA) present in the solution but at the unmodified CPE the peak potentials were indistinguishable. This method was also examined for determination of EP in EP injection.

  1. Natural Biological Attenuation of Benzene in Groundwater

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Benzene has been found in subsurface unsaturated soil and groundwater beneath a petro-chemical plant. Although the groundwater contained several mg/L of benzene in the area immediately beneath the source, benzene was not detected in monitoring wells approximately 800m down stream. All kinds of physical processes such as adsorption and advection/dispersion are considered to account for the observed attenuation. The results indicated that the attenuation was primarily due to natural biological processes occurring within the aquifer. The evidence for the natural bioremediation of benzene from the groundwater included: (1) analysis of groundwater chemistry, (2) laboratory studies demonstrating benzene biodegradation in aquifer samples, and (3) computer simulations examining benzene transport. Laboratory experiments indicated that for conditions similar to those in the plume, the aerobic degradation of benzene by the naturally occurring microorganisms in the polluted groundwater samples was quite rapid with a half-life time of from 5 to 15 days. In situ analyses indicated the level of dissolved oxygen in the groundwater was over 2mg/L. Thus, oxygen should not limit the biodegradation. In fact, the benzene was also shown to degrade under anaerobic conditions. The results from the modeling simulations indicate that biodegradation is the dominant process influencing attenuation of the benzene.

  2. Neptunium redox behavior and sorption onto goethite and hematite in the presence of humic acids with different hydroquinone content

    Energy Technology Data Exchange (ETDEWEB)

    Khasanova, A.B. [Lomonosov Moscow State University, Chemistry Department, Moscow 119992 (Russian Federation)], E-mail: aigul@radio.chem.msu.ru; Kalmykov, St.N.; Perminova, I.V. [Lomonosov Moscow State University, Chemistry Department, Moscow 119992 (Russian Federation); Clark, S.B. [Washington State University, Chemistry Department, Pullman, WA 99164-4630 (United States)

    2007-10-11

    The effect of humic acids (HA) on neptunium redox behavior and sorption onto hematite, {alpha}-Fe{sub 2}O{sub 3}, and goethite, {alpha}-FeOOH, colloids was established in batch sorption experiments that were carried out in broad pH interval. The sorption isotherms were provided for two samples of HA: commercial sample of leonardite humic acid and its hydroquinone-enriched derivative obtained using formaldehyde copolycondensation. The distribution of Np fitted the distribution of hydroquinone-enriched HA at low pH values in case of both solids while the influence of parent HA on Np sorption was negligible. This is due to Np(V) reduction upon interaction with hydroquinone-enriched derivative having higher reducing capacity compared to the parent HA. The order of components addition was found to be significant for Np retention.

  3. 46 CFR 30.25-3 - Benzene.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Benzene. 30.25-3 Section 30.25-3 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS GENERAL PROVISIONS Commodities Regulated § 30.25-3 Benzene. The provisions contained in 46 CFR part 197, subpart C, apply to liquid cargoes containing 0.5% or more...

  4. 46 CFR 151.50-60 - Benzene.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Benzene. 151.50-60 Section 151.50-60 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES BARGES CARRYING BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-60 Benzene. The person in charge of...

  5. 29 CFR 1926.1128 - Benzene.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Benzene. 1926.1128 Section 1926.1128 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Toxic and Hazardous Substances § 1926.1128 Benzene....

  6. 29 CFR 1915.1028 - Benzene.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Benzene. 1915.1028 Section 1915.1028 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED... Benzene. Note: The requirements applicable to shipyard employment under this section are identical...

  7. Bio sensing Benzene in the refinery

    International Nuclear Information System (INIS)

    A biosensor based on Pseudomonas putida cells was utilized for Benzene analysis in air of an oil refinery. Biosensoristic approach was compared to gaschromatografic essay. We also developed bio sensing Benzene genetically modified Escherichia coli and tested them with refinery samples. Microbial biosensor were useful to determine air pollution.

  8. Molecular dynamics simulation of benzene

    Science.gov (United States)

    Trumpakaj, Zygmunt; Linde, Bogumił B. J.

    2016-03-01

    Intermolecular potentials and a few models of intermolecular interaction in liquid benzene are tested by Molecular Dynamics (MD) simulations. The repulsive part of the Lennard-Jones 12-6 (LJ 12-6) potential is too hard, which yields incorrect results. The exp-6 potential with a too hard repulsive term is also often used. Therefore, we took an expa-6 potential with a small Gaussian correction plus electrostatic interactions. This allows to modify the curvature of the potential. The MD simulations are carried out in the temperature range 280-352 K under normal pressure and at experimental density. The Rayleigh scattering of depolarized light is used for comparison. The results of MD simulations are comparable with the experimental values.

  9. Exposição a hidroquinona e ao fenol sobre a resposta inflamatória pulmonar induzida por bactéria Hydroquinone and phenol exposure on pulmonary inflammatory response induced by bacteria

    Directory of Open Access Journals (Sweden)

    Alexandre Ferreira

    2007-09-01

    Full Text Available A gravidade dos efeitos causados pela exposição ambiental e ocupacional ao benzeno determinou o controle de sua utilização. No entanto, mesmo nestas condições, toxicidade ao sistema imune e nervoso tem sido descrita. A toxicidade do benzeno é determinada pelos seus produtos de biotransformação, em que fenol (FE e hidroquinona (HQ têm papel relevante na imunotoxicidade. Neste contexto, o presente trabalho mostra que a exposição de ratos Wistar, machos, a doses de 5 ou 10 mg/kg de HQ (via i.p., uma vez ao dia, 13 doses consecutivas, com intervalos de 2 dias a cada 5 doses provocou reduções acentuadas no influxo de leucócitos polimorfonucleares (PMN e mononucleares (MN para o pulmão 24 horas após inalação de Lipopolissacarídeo (LPS de Salmonella abortus. Diferentemente, a migração de leucócitos em animais expostos ao FE não foi alterada. A exposição a ambos os agentes químicos simultaneamente (dose de 5 mg/kg cada manteve a redução na migração de MN detectada em animais expostos à HQ e potencializou o efeito inibitório da HQ sobre a migração de leucócitos PMN. Os prejuízos nas migrações de leucócitos não foram decorrentes de modificações no número destas células na circulação. É importante ressaltar que os efeitos foram induzidos por doses dos agentes químicos que não causaram prejuízo à função hepática ou renal, determinados pela atividade das transaminases hepáticas e a concentração de creatinina no soro. Em conjunto, os dados obtidos mostram a exposição a baixas doses de HQ não provoca alterações nos parâmetros empregados como indicadores de toxicidade. No entanto, os efeitos tóxicos são manifestados resposta do organismo ao trauma.The high toxicity induced by occupational and environmental benzene exposure lead to its use restriction. However, at these conditions, neuronal and immune toxicity has been described. It is well known that benzene metabolites, such as hydroxyl

  10. A chemiluminescence method to detect hydroquinone with water-soluble sulphonato-(salen)manganese(III) complex as catalyst.

    Science.gov (United States)

    Zhang, Guangbin; Tang, Yuhai; Sun, Yang; Yu, Hua; Du, Wei; Fu, Qiang

    2016-02-01

    A water-soluble sulphonato-(salen)manganese(III) complex with excellent catalytic properties was synthesized and demonstrated to greatly enhance the chemiluminescence signal of the hydrogen peroxide - luminol reaction. Coupled with flow-injection technique, a simple and sensitive chemiluminescence method was first developed to detect hydroquinone based on the chemiluminescence system of the hydrogen peroxide-luminol-sulphonato-(salen)manganese(III) complex. Under optimal conditions, the assay exhibited a wide linear range from 0.1 to 10 ng mL(-1) with a detection limit of 0.05 ng mL(-1) for hydroquinone. The method was applied successfully to detect hydroquinone in tap-water and mineral-water, with a sampling frequency of 120 times per hour. The relative standard deviation for determination of hydroquinone was less than 5.6%, and the recoveries ranged from 96.8 to 103.0%. The ultraviolet spectra, chemiluminescence spectra, and the reaction kinetics for the peroxide-luminol-sulphonato-(salen)manganese(III) complex system were employed to study the possible chemiluminescence mechanism. The proposed chemiluminescence analysis technique is rapid and sensitive, with low cost, and could be easily extended and applied to other compounds. PMID:26014972

  11. CATALYTIC WET PEROXIDE OXIDATION OF HYDROQUINONE WITH Co(II)/ACTIVE CARBON CATALYST LOADED IN STATIC BED

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Catalysts based on Co(II) supported on active carbon were prepared and loaded in static bed. The hydroquinone would be degraded completely after treated by Catalytic wet peroxide oxidation method with Co(II)/active carbon catalyst. After activate treatment, the active carbon was immerged in cobaltous nitrate solution, then put into a drying oven, Co(II) could be loaded on the micro-surface of carbon. Taking the static bed as the equipment, the absorption of active carbon and catalysis of Co(II) was used to reduce activation energy of hydroquinone. Thus hydroquinone could be drastically degraded and the effluent can be drained under the standard. Referring to Fenton reaction mechanism, experiment had been done to study the heterogeneous catalyzed oxidation mechanism of Co(II). The degradation rate of hydroquinone effluent could be achieved to 92% when treated in four columns at H2O2 concentration 10%, reaction temperature 40℃ , pH 5 and reaction time 2.5h.

  12. CATALYTIC WET PEROXIDE OXIDATION OF HYDROQUINONE WITH Co(Ⅱ)/ACTIVE CARBON CATALYST LOADED IN STATIC BED

    Institute of Scientific and Technical Information of China (English)

    LI Chunxiang; YAN Yongsheng; XU Wanzhen

    2008-01-01

    Catalysts based on Co(Ⅱ) supported on active carbon were prepared and loaded in static bed.The hydroquinone wouid be degraded completely after treated by Catalytic wet peroxide oxidation method with Co(Ⅱ)/active carbon catalyst.After activate treatment, the active carbon was immerged in cobaltoas nitrate solution, then put into a drying oven, Co(Ⅱ) could be loaded on the micro-surface of carbon.Taking the static bed as the equipment, the absorption of active carbon and catalysis of Co(Ⅱ) was used to reduce activation energy of hydroquinone.Thus hydroquinone could be drastically degraded and the effluent can be drained under the standard.Referring to Fenton reaction mechanism, experiment had been done to study the heterogeneous catalyzed oxidation mechanism of Co(Ⅱ).The degradation rate of hydroquinone effluent could be achieved to 92% when treated in four columns at H2O2 concentration 10%, reaction temperature 40℃, pH 5 and reaction time 2.5h.

  13. Evaluation of various strategies to formation of pH responsive hydroquinone-terminated films on carbon electrodes

    DEFF Research Database (Denmark)

    Holm, A.H.; Vase, K.H.; Winther-Jensen, Bjørn; Pedersen, S.U.; Daasbjerg, Kim

    2007-01-01

    The hydroquinone/quinone (H(2)Q/Q) redox system was tethered to glassy carbon surfaces using first an electrochemical pre-oxidation treatment to afford carboxylic acid functionalities followed by immobilizing the H(2)Q Precursor, n-(2,5-dimethoxyphenyl)alkan-1-amine (general structure: H2N-(CH2)(...

  14. Co(salophen)-Catalyzed Aerobic Oxidation of p-Hydroquinone: Mechanism and Implications for Aerobic Oxidation Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Anson, Colin W.; Ghosh, Soumya; Hammes-Schiffer, Sharon; Stahl, Shannon S.

    2016-03-30

    Macrocyclic metal complexes and p-benzoquinones are commonly used as co-catalytic redox mediators in aerobic oxidation reactions. In an effort to gain insight into the mechanism and energetic efficiency of these reactions, we investigated Co(salophen)-catalyzed aerobic oxidation of p-hydroquinone. Kinetic and spectroscopic data suggest that the catalyst resting-state consists of an equilibrium between a CoII(salophen) complex, a CoIII-superoxide adduct, and a hydrogen-bonded adduct between the hydroquinone and the CoIII–O2 species. The kinetic data, together with density functional theory data, suggest that the turnover-limiting step features proton-coupled electron transfer from a semi-hydroquinone species and a CoIII-hydroperoxide intermediate. Additional experimental and computational data suggest that a coordinated H2O2 intermediate oxidizes a second equivalent of hydroquinone. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center, funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. The NSF provided partial support for the EPR instrumentation (NSF CHE-0741901).

  15. Excited state of protonated benzene and toluene

    International Nuclear Information System (INIS)

    We present photo-fragmentation electronic spectra of the simplest protonated aromatic molecules, protonated benzene and toluene, recorded under medium resolution conditions and compared with the photo-fragmentation spectrum of protonated pyridine. Despite the resolution and cold temperature achieved in the experiment, the electronic spectra of protonated benzene and toluene are structure-less, thus intrinsically broadened. This is in agreement with the large geometrical changes and the fast dynamic toward internal conversion predicted by ab initio calculations for protonated benzene [Rode et al., J. Phys. Chem. A 113, 5865–5873 (2009)

  16. An electrochemically aminated glassy carbon electrode for simultaneous determination of hydroquinone and catechol.

    Science.gov (United States)

    Wang, Xiuyun; Xi, Min; Guo, Mengmeng; Sheng, Fangmeng; Xiao, Guang; Wu, Shuo; Uchiyama, Shunichi; Matsuura, Hiroaki

    2016-02-01

    In this contribution, a very simple and reliable strategy based on the easy modification of a glassy carbon electrode (GCE) by pre-electrolyzing GCE in ammonium carbamate aqueous solution was employed for the simultaneous determination of hydroquinone (HQ) and catechol (CC). Compared with bare GCE, the incorporation of nitrogen into the GCE surface structure improved the electrocatalytic properties of GCE towards the electro-oxidation of HQ and CC. The nitrogen-introduced GCE (N-GCE) was evaluated for the simultaneous detection of HQ and CC and the linear ranges for HQ and CC were both from 5 to 260 μM. Their detection limits were both evaluated to be 0.2 μM (S/N = 3). The present method was applied for the determination of HQ and CC in real river water samples with recoveries of 95.0-102.1%. In addition, a possible detection mechanism of HQ and CC was discussed. PMID:26613194

  17. Structural Collapse of the Hydroquinone-Formic Acid Clathrate: A Pressure-Medium-Dependent Phase Transition.

    Science.gov (United States)

    Eikeland, Espen; Thomsen, Maja K; Madsen, Solveig R; Overgaard, Jacob; Spackman, Mark A; Iversen, Bo B

    2016-03-14

    The energy landscape governing a new pressure-induced phase transition in the hydroquinone-formic acid clathrate is reported in which the host structure collapses, opening up the cavity channels within which the guest molecules migrate and order. The reversible isosymmetric phase transition causes significant changes in the morphology and the birefringence of the crystal. The subtle intermolecular interaction energies in the clathrate are quantified at varying pressures using novel model energies and energy frameworks. These calculations show that the high-pressure phase forms a more stable host network at the expense of less-stable host-guest interactions. The phase transition can be kinetically hindered using a nonhydrostatic pressure-transmitting medium, enabling the comparison of intermolecular energies in two polymorphic structures in the same pressure range. Overall this study illustrates a need for accurate intermolecular energies when analyzing self-assembly structures and supramolecular aggregates. PMID:26879515

  18. Four component catalysis for the hydroalkylation of benzene to cyclohexyl benzene

    Energy Technology Data Exchange (ETDEWEB)

    Fahy, J.; Trimm, D.L. [School of Chemical Engineering and Industrial Chemistry, University of New South Wales, NSW 2052 Sydney (Australia); Cookson, D.J. [BHP Melbourne Research Laboratories, Vic. Melbourne (Australia)

    2001-04-13

    Patent claims that benzene can be hydroalkylated to form cyclohexyl benzene - a potential diesel fuel - over a four component catalyst have been verified, and the role of the individual components has been explored. The hydrogenation of benzene over nickel on zeolite 13X produced reasonably high (ca. 30%) yields of cyclohexane, but the product distribution favoured cyclohexyl benzene in the presence of rare earth ions. The addition of small (ca. 1%) of platinum produced good yields and selectivities to cyclohexyl benzene at ca. 450K, a performance which was matched only at ca. 670K in the absence of platinum. Temperature programmed studies showed that Pt promoted the low temperature reduction of the catalyst to produce better performance. The acidic 13X molecular sieve promoted alkylation, but acidity was not the only factor involved. Rare earth additions were suggested to induce electron transfer to the nickel, weakening adsorption of benzene and promoting hydroalkylation rather than hydrogenation.

  19. 46 CFR 197.565 - Notifying personnel of benzene hazards.

    Science.gov (United States)

    2010-10-01

    ... appendices A and B of this subpart or a MSDS on benzene meeting the requirements of 29 CFR 1910.1200(g) is... 46 Shipping 7 2010-10-01 2010-10-01 false Notifying personnel of benzene hazards. 197.565 Section... AND HEALTH STANDARDS GENERAL PROVISIONS Benzene § 197.565 Notifying personnel of benzene hazards....

  20. Recommended sublimation pressure and enthalpy of benzene

    International Nuclear Information System (INIS)

    Highlights: • Sublimation pressures of benzene were measured. • Benzene thermodynamic properties in the state of ideal gas were calculated. • Recommended sublimation pressure and enthalpy of benzene were developed. -- Abstract: Recommended vapor pressures of solid benzene (CAS Registry Number: 71-43-2) which are consistent with thermodynamically related crystalline and ideal-gas heat capacities as well as with properties of the liquid phase at the triple point temperature (vapor pressure, enthalpy of vaporization) were established. The recommended data were developed by a multi-property simultaneous correlation of vapor pressures and related thermal data. Vapor pressures measured in this work using the static method in the temperature range from 233 K to 260 K, covering pressure range from 99 Pa to 1230 Pa, were included in the simultaneous correlation. The enthalpy of sublimation was established with uncertainty significantly lower than the previously recommended values

  1. Consistent assignment of the vibrations of symmetric and asymmetric para-disubstituted benzene molecules

    Science.gov (United States)

    Andrejeva, Anna; Gardner, Adrian M.; Tuttle, William D.; Wright, Timothy G.

    2016-03-01

    We give a description of the phenyl-ring-localized vibrational modes of the ground states of the para-disubstituted benzene molecules including both symmetric and asymmetric cases. In line with others, we quickly conclude that the use of Wilson mode labels is misleading and ambiguous; we conclude the same regarding the related ones of Varsányi. Instead we label the modes consistently based upon the Mulliken (Herzberg) method for the modes of para-difluorobenzene (pDFB). Since we wish the labelling scheme to cover both symmetrically- and asymmetrically-substituted molecules, we apply the Mulliken labelling under C2v symmetry. By studying the variation of the vibrational wavenumbers with mass of the substituent, we are able to identify the corresponding modes across a wide range of molecules and hence provide consistent assignments. Particularly interesting are pairs of vibrations that evolve from in- and out-of-phase motions in pDFB to more localized modes in asymmetric molecules. We consider the para isomers of the following: the symmetric dihalobenzenes, xylene, hydroquinone, the asymmetric dihalobenzenes, halotoluenes, halophenols and cresol.

  2. The first clinical experience on efficacy of topical flutamide on melasma compared with topical hydroquinone: a randomized clinical trial

    Directory of Open Access Journals (Sweden)

    Adalatkhah H

    2015-08-01

    Full Text Available Hassan Adalatkhah,1 Homayoun Sadeghi-Bazargani2,3 1Department of Dermatology, Ardabil University of Medical Sciences, Ardabil, Iran; 2Road Traffic Injury Research Center, Department of Statistics and Epidemiology, Tabriz University of Medical Sciences, Tabriz, Iran; 3Department of Public Health Sciences, Karolinska Institute, Stockholm, Sweden Background: Treatment of melasma is unsatisfactory most of the times. Hormonal role is shown to exist in pathogenesis of the melasma, and sex-hormone related drugs may have an effect on melasma.Aim: To investigate efficacy of 1% flutamide cream versus 4% hydroquinone cream on melasma.Methods: In a parallel randomized clinical trial, 74 women with melasma were allocated to receive a sunscreen along with 4% hydroquinone cream or 1% flutamide cream. Melasma Area and Severity Index (MASI, mexameter melanin assay, and patient satisfaction were investigated.Results: Mean age of the participants was 33.8 years. Mean length of time suffering from Melasma was 96.3 months. The subjects reported in average 1.1 hours per day of exposure to sunlight. Mean standardized total patient satisfaction score was 28.8 (standard deviation [SD] 17.2 in flutamide group patients versus 18 (SD 15.5 in control group (P<0.01. Regardless of treatment group, the skin darkness assessed upon MASI scales was reduced over the treatment course (P<0.001. Using mixed effects, longitudinal modeling showed better treatment efficacy based on MASI scale for flutamide group compared to the hydroquinone group (P<0.05. However, longitudinal analysis of mexameter scores did not reveal any significant difference in melanin measurements between flutamide and hydroquinone.Conclusion: Topical flutamide appeared as effective as topical hydroquinone in treating melasma using mexameter assessment but with a better MASI improvement trend and higher patient satisfaction in flutamide treatment versus topical hydroquinone. As the present study is possibly the

  3. Radiolysis of Aqueous Benzene Solutions

    International Nuclear Information System (INIS)

    Aerated and deaerated aqueous solutions of benzene have been irradiated with 60Co γ-rays. The products of radiolysis in deaerated, unbuffered or acid, solutions were phenol, biphenyl, hydrogen and in acid solutions also hydrogen peroxide with the following yields: G(phenol) = 0. 37 (0. 37), G(biphenyl) = 1.3 (1.7), G(H2) = 0.44 (0. 43) and G(H2O2) = 0 (0.60), the figures in brackets giving the results for acid solutions. The results are shown to agree with the conclusion that k(e-aq + H2O2) >> k(H + H2O2). Furthermore, the results indicate that a competition takes place between the reactions: 2 C6H6OH · -> dimer -> biphenyl. C6H7 · + C6H6OH · -> dimer -> biphenyl. The yields in aerated, unbuffered or acid, solutions were: G(phenol) = 2.1 (2.3), G(biphenyl) = 0 (0), and G(H2O2) = 2.2 (3.1), the figures in brackets being valid for acid solutions. The ratio k(H + C6H6)/k(H + O2) was 1.4x10-2. The results indicate that peroxides, or more probably hydroperoxides, take part in the reactions. After the addition of Fe2+ or Fe3+ to aerated acid solutions G(phenol) was increased to 6.6 and 3.4 respectively. Oxygen was consumed more rapidly in the presence of Fe. Reaction mechanisms are discussed

  4. A Comparative Study of the Efficacy of 4% Hydroquinone vs 0.75% Kojic Acid Cream in the Treatment of Facial Melasma

    OpenAIRE

    Monteiro, Rochelle C; Kishore, B Nanda; Bhat, Ramesh M.; D Sukumar; Martis, Jacintha; Ganesh, H Kamath

    2013-01-01

    Background: Melasma is a common acquired cause of facial hyperpigmentation seen predominantly among females with significant psychological and social impact. It is often recalcitrant to treatment. Several topical hypopigmenting agents have been used to combat melasma. Hydroquinone and Kojic Acid are well established monotherapeutic agents for treating melasma. Objectives: This study focuses mainly on the efficacy of once daily application of 4% Hydroquinone and 0.75% Kojic Acid cream (contain...

  5. A comparative study of the efficacy of 4% hydroquinone vs 0.75% Kojic acid cream in the treatment of facial melasma

    OpenAIRE

    Monteiro, Rochelle C; B Nanda Kishore; Bhat, Ramesh M.; D Sukumar; Jacintha Martis; H Kamath Ganesh

    2013-01-01

    Background: Melasma is a common acquired cause of facial hyperpigmentation seen predominantly among females with significant psychological and social impact. It is often recalcitrant to treatment. Several topical hypopigmenting agents have been used to combat melasma. Hydroquinone and Kojic Acid are well established monotherapeutic agents for treating melasma. Objectives: This study focuses mainly on the efficacy of once daily application of 4% Hydroquinone and 0.75% Kojic Acid cream (contain...

  6. Comparison between the efficacy of 10% zinc sulfate solution with 4% hydroquinone cream on improvement of melasma

    OpenAIRE

    Iraji, Fariba; Tagmirriahi, Nabet; Gavidnia, Keyvan

    2012-01-01

    Background: Melasma, a common disorder of hyperpigmentation, is often difficult to treat. Although 10% zinc sulfate solution has been reported to be useful for patients with melasma, controlled trials are lacking. Materials and Methods: 72 women with moderate to severe melasma were divided randomly into 2 groups. Group A were treated with 10% zinc sulfate solution and group B with 4% hydroquinone cream twice-daily. The results were evaluated by photoevaluation by patients based on subjective ...

  7. Comparison between the efficacy of 10% zinc sulfate solution with 4% hydroquinone cream on improvement of melasma

    OpenAIRE

    Fariba Iraji; Nabet Tagmirriahi; Keyvan Gavidnia

    2012-01-01

    Background: Melasma, a common disorder of hyperpigmentation, is often difficult to treat. Although 10% zinc sulfate solution has been reported to be useful for patients with melasma, controlled trials are lacking. Materials and Methods: 72 women with moderate to severe melasma were divided randomly into 2 groups. Group A were treated with 10% zinc sulfate solution and group B with 4% hydroquinone cream twice-daily. The results were evaluated by photoevaluation by patients based on subject...

  8. A Double-Blind, Randomized Clinical Trial of Niacinamide 4% versus Hydroquinone 4% in the Treatment of Melasma

    OpenAIRE

    Josefina Navarrete-Solís; Juan Pablo Castanedo-Cázares; Bertha Torres-µlvarez; Cuauhtemoc Oros-Ovalle; Cornelia Fuentes-Ahumada; Francisco Javier González; Juan David Martínez-Ramírez; Benjamin Moncada

    2011-01-01

    Background. Multiple modalities have been used in the treatment of melasma with variable success. Niacinamide has anti-inflammatory properties and is able to decrease the transfer of melanosomes. Objective. To evaluate the therapeutic effect of topical niacinamide versus hydroquinone (HQ) in melasma patients. Patients and Methods. Twenty-seven melasma patients were randomized to receive for eight weeks 4% niacinamide cream on one side of the face, and 4% HQ cream on the other. Sunscreen was a...

  9. Self-assembly of graphitic carbon nitride nanosheets–carbon nanotube composite for electrochemical simultaneous determination of catechol and hydroquinone

    International Nuclear Information System (INIS)

    Graphical abstract: Schematic diagram of hydrothermal synthesis graphitic carbon nitride nanosheets-carbon nanotube composite and theirs application for electrochemical sensing catechol and hydroquinone. - Highlights: • Self-assembly of graphitic carbon nitride nanosheets-carbon nanotube composite. • CNNS-CNT show more stronger conductivity than CNNS and CNT. • CNNS-CNT has been performed for detection of catechol and hydroquinone. • The probe was applied to detect practical samples with satisfactory results. - Abstract: In this paper, three-dimensional (3D) graphitic carbon nitride nanosheets-carbon nanotube (CNNS-CNT) composite was synthesized via hydrothermal reaction of 2D CNNS and 1D CNT-COOH by π-π stacking and electrostatic interactions. This CNNS-CNT composite was characterized by transmission electron microscope, scanning electron microscope, x-ray diffraction and fourier-transform infrared. In addition, the CNNS-CNT composite displayed excellent conductivity comparing with CNNS and CNT-COOH monomer. This composite was applied for electrochemical simultaneous determination of catechol (CC) and hydroquinone (HQ) with good sensitivity, wide linear range and low detection limit. In addition, this CNNS-CNT composite modified electrode was also applied to detect practical samples with satisfactory results

  10. High-performance Liquid Chromatographic Determination of Urinary Trans, Trans-Muconic Acid Excreted by Workers Occupationally Exposed to Benzene

    Institute of Scientific and Technical Information of China (English)

    XIA-MIN HU; SHI-ZHEN SONG; FANG-LI YE; LI-WEN LIU

    2006-01-01

    To investigate the relationship between trans, trans-muconic acid (ttMA) as benzene metabolite of occupational workers and benzene concentration in air. Methods A rapid and sensitive high-performance liquid chromatography was developed to determine the level of urinary ttMA. ttMA was extrated from urinary samples in liquid-liquid phase a ODS (2) (5u) column (Φ4.6 mm× 150 mm) and detected at wavelength 264 nm in a UV detector using vanillic acid as an internal standard. The mobile phase was acetaticacid/tetrahydrofuran/methanol/water (v/v, 1:2:10:87). The method was validated with 56 urine samples collected from occupationally benzene-exposed individuals. Results A correlation coefficient (r = 0.9963 ) was found for ttMA ranging 0.10-10.00 μg/mL. The limit of detection was 0.10 μg/mL. The recovery and reproducibility were generally over 90%. There was a positive correlation between ttMA and benzene level in air. The equation was Y=0.859+0.108C (before work, r=-0.6200) or Y=1.980+0.179C (after work, r=0.7930). Conclusion This method can be used to determine and control the level of urinary ttMA in those who are occupationally exposed to benzene.

  11. Hydroquinone-ZnO nano-laminate deposited by molecular-atomic layer deposition

    International Nuclear Information System (INIS)

    In this study, we have deposited organic-inorganic hybrid semiconducting hydroquinone (HQ)/zinc oxide (ZnO) superlattices using molecular-atomic layer deposition, which enables accurate control of film thickness, excellent uniformity, and sharp interfaces at a low deposition temperature (150 °C). Self-limiting growth of organic layers is observed for the HQ precursor on ZnO surface. Nano-laminates were prepared by varying the number of HQ to ZnO cycles in order to investigate the physical and electrical effects of different HQ to ZnO ratios. It is indicated that the addition of HQ layer results in enhanced mobility and reduced carrier concentration. The highest Hall mobility of approximately 2.3 cm2/V·s and the lowest n-type carrier concentration of approximately 1.0 × 1018/cm3 were achieved with the organic-inorganic superlattice deposited with a ratio of 10 ZnO cycles to 1 HQ cycle. This study offers an approach to tune the electrical transport characteristics of ALD ZnO matrix thin films using an organic dopant. Moreover, with organic embedment, this nano-laminate material may be useful for flexible electronics

  12. Direct and Simultaneous Determination of Phenol, Hydroquinone and Nitrophenol at Boron-Doped Diamond Film Electrode

    Institute of Scientific and Technical Information of China (English)

    ZHAO, Guo-Hua; TANG, Yi-Ting; LIU, Mei-Chuan; LEI, Yan-Zhu; XIAO, Xiao-E

    2007-01-01

    The electrochemical characteristics of multi-component phenolic pollutants, such as phenol (Ph), hydroquinone (HQ) and 4-nitrophenol (4-NP), were investigated on boron-doped diamond (BDD) film electrode by differential pulse voltammetry (DPV) technique. A simple and feasible platform was accordingly established for the direct and simultaneous determination of these three phenolic pollutants. Results showed that, Ph, HQ and 4-NP gave obvious oxidation peaks on BDD electrode at the potential of 1.24, 0.76 and 1.52 V, respectively. Each of them displayed good linear relationship between their oxidation peak currents and their corresponding concentrations in a rather wide range coexisting with one or two of the other phenolic pollutants. The detection limits of Ph, HQ and 4-NP were estimated to be as low as 1.82×10-6, 1.67×10-6 and 1.44×10-6mol·L-1, respectively. Therefore, a promising direct and simultaneous electrochemical determination method of multi-component phenolic pollutants in wastewater samples was constructed successfully on BDD electrode with advantages being rapid, simple, convenient, sensitive, in situ and inexpensive.

  13. Electrode Prepared with Combination of Different Conductive Polymers for Hydroquinone Determination in River Water.

    Science.gov (United States)

    Ülker, Emine; Kavanoz, Muammer

    2016-01-01

    Modified electrode based on combination of different conductive polymers (Polyaniline - Poly(3-methylthiophene) - Poly(3,3' diaminobenzidine) (PANI - P3MT - PDAB)) was previously synthesized in dichloromethane containing HClO4 and tetrabutylammoniumperchlorate (TBAP) supporting electrolyte. In this study, determination of hydroquinone (HQ) with amperometric I-t method over this modified and its homopolymers coated electrode was successfully carried out in river water as real sample and in solution consisting of NaHSO4/Na2SO4 (pH 2.0). For this method, potentials between 0.45 V and 0.65 V were applied and the best analytical response was obtained at 0.55 V using this modified electrode when compared its homopolymer. The limit of detection (LOD), limit of quantification (LOQ) , the linear dynamic range and regression coefficient (R2) were found as 1.31x10-4 mM, 4.37x10-4 mM, 4.37x10-4- 95.0 mM and 0.998, respectively. These results were compared to homopolymers coated and uncoated Pt electrodes. For checking on the accuracy of the developed method and the matrices interference, determination of HQ was performed in artificially contaminated river water samples with HQ concentration 5.0 mM and 10.0 mM using this modified electrode and recovery values were calculated as % 100.6 and % 100.1, respectively. PMID:26970788

  14. Simultaneous Determination of Hydroquinone, Catechol and Resorcinol at Graphene Doped Carbon Ionic Liquid Electrode

    Directory of Open Access Journals (Sweden)

    Li Ma

    2012-01-01

    Full Text Available A new composite electrode has been prepared with doping graphene into the paste consisting graphite and ionic liquid, n-octyl-pyridinum hexafluorophosphate (OPFP. This electrode shows an excellent electrochemical activity for the redox of hydroquinone (HQ, catechol (CC, and resorcinol (RS. In comparison with bare paste electrode, the redox peaks of three isomers of dihydroxybenzene can be obviously, simultaneously observed at graphene doping paste electrode. Under the optimized condition, the simultaneous determination of HQ, CC, and RS in their ternary mixture can be carried out with a differential pulse voltammetric technique. The peak currents are linear to the concentration of HQ, CC, and RS in the range form 1×10−5 to 4×10−4, 1×10−5 to 3×10−4, and 1×10−6 to 1.7×10−4 mol L−1, respectively. The limits of detection are 1.8×10−6 mol L−1 for HQ, 7.4×10−7 mol L−1 for CC, and 3.6×10−7 M for RS, respectively.

  15. Control of size and aspect ratio in hydroquinone-based synthesis of gold nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Morasso, Carlo, E-mail: cmorasso@dongnocchi.it; Picciolini, Silvia; Schiumarini, Domitilla [Fondazione Don Carlo Gnocchi ONLUS, Laboratory of Nanomedicine and Clinical Biophotonics (LABION) (Italy); Mehn, Dora; Ojea-Jiménez, Isaac [European Commission Joint Research Centre, Institute for Health and Consumer Protection (IHCP) (Italy); Zanchetta, Giuliano [Universitá degli Studi di Milano, Dipartimento di Biotecnologie Mediche e Medicina Traslazionale (Italy); Vanna, Renzo; Bedoni, Marzia [Fondazione Don Carlo Gnocchi ONLUS, Laboratory of Nanomedicine and Clinical Biophotonics (LABION) (Italy); Prosperi, Davide [Università degli Studi di Milano Bicocca, NanoBioLab, Dipartimento di Biotecnologie e Bioscienze (Italy); Gramatica, Furio [Fondazione Don Carlo Gnocchi ONLUS, Laboratory of Nanomedicine and Clinical Biophotonics (LABION) (Italy)

    2015-08-15

    In this article, we describe how it is possible to tune the size and the aspect ratio of gold nanorods obtained using a highly efficient protocol based on the use of hydroquinone as a reducing agent by varying the amounts of CTAB and silver ions present in the “seed-growth” solution. Our approach not only allows us to prepare nanorods with a four times increased Au{sup 3+} reduction yield, when compared with the commonly used protocol based on ascorbic acid, but also allows a remarkable reduction of 50–60 % of the amount of CTAB needed. In fact, according to our findings, the concentration of CTAB present in the seed-growth solution do not linearly influence the final aspect ratio of the obtained nanorods, and an optimal concentration range between 30 and 50 mM has been identified as the one that is able to generate particles with more elongated shapes. On the optimized protocol, the effect of the concentration of Ag{sup +} ions in the seed-growth solution and the stability of the obtained particles has also been investigated.

  16. Methionine – Au Nanoparticle Modified Glassy Carbon Electrode: a Novel Platform for Electrochemical Detection of Hydroquinone

    Directory of Open Access Journals (Sweden)

    Jiahong HE

    2014-12-01

    Full Text Available A high sensitive electrochemical sensor based on methionine/gold nanoparticles (MET/AuNPs modified glassy carbon electrode (GCE was fabricated for the quantitative detection of hydroquinone (HQ. The as-modified electrode was characterized by scanning electron microscopy (SEM and X-ray diffraction (XRD techniques. The electrochemical performance of the sensor to HQ was investigated by using cyclic and differential pulse voltammetry, which revealed its excellent electrocatalytic activity and reversibility towards HQ. The separation of anodic and cathodic peak (∆Ep was decreased from 471 mV to 75 mV. The anodic peak current achieved under the optimum conditions was linear with the HQ concentration ranging from 8 μM to 400 μM with the detection limit 0.12 μM (3σ. The as-fabricated sensor also showed a good selectivity towards HQ without demonstrating interference from other coexisting species. Furthermore, the sensor showed a good performance for HQ detection in environmental water, which suggests its potential practical application. DOI: http://dx.doi.org/10.5755/j01.ms.20.4.6477

  17. Control of size and aspect ratio in hydroquinone-based synthesis of gold nanorods

    International Nuclear Information System (INIS)

    In this article, we describe how it is possible to tune the size and the aspect ratio of gold nanorods obtained using a highly efficient protocol based on the use of hydroquinone as a reducing agent by varying the amounts of CTAB and silver ions present in the “seed-growth” solution. Our approach not only allows us to prepare nanorods with a four times increased Au3+ reduction yield, when compared with the commonly used protocol based on ascorbic acid, but also allows a remarkable reduction of 50–60 % of the amount of CTAB needed. In fact, according to our findings, the concentration of CTAB present in the seed-growth solution do not linearly influence the final aspect ratio of the obtained nanorods, and an optimal concentration range between 30 and 50 mM has been identified as the one that is able to generate particles with more elongated shapes. On the optimized protocol, the effect of the concentration of Ag+ ions in the seed-growth solution and the stability of the obtained particles has also been investigated

  18. Dehydrogenation of benzene on Pt(111) surface

    Science.gov (United States)

    Gao, W.; Zheng, W. T.; Jiang, Q.

    2008-10-01

    The dehydrogenation of benzene on Pt(111) surface is studied by ab initio density functional theory. The minimum energy pathways for benzene dehydrogenation are found with the nudge elastic band method including several factors of the associated barriers, reactive energies, intermediates, and transient states. The results show that there are two possible parallel minimum energy pathways on the Pt(111) surface. Moreover, the tilting angle of the H atom in benzene can be taken as an index for the actual barrier of dehydrogenation. In addition, the properties of dehydrogenation radicals on the Pt(111) surface are explored through their adsorption energy, adsorption geometry, and electronic structure on the surface. The vibrational frequencies of the dehydrogenation radicals derived from the calculations are in agreement with literature data.

  19. Ionic Liquid Catalyst Used in Deep Desulfuration of the Coking Benzene for Producing Sulfurless Benzene

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xia-Ping; WANG Yan-Liang; MENG Fan-Wei; FAN Xing-Ming; QIN Song-Bo

    2008-01-01

    For the widening need of benzene used in organic synthesis, ionic liquid catalyst was prepared to study the process of deep desulfuration in the coking benzene. The result shows that the effect of de-thiophene by the ionic liquid catalyst (N-methyl imidazolium hydrogen sulfate [Hmim][HSO4]) is related to its acid function value.Hammett indicator was used to determine the acid function value H0 of the ionic liquid. It can be concluded that while the acid function value is in the range from -4 to -12, the ionic liquid catalyst can make the concentration certain acid quantity and strength, the ionic liquid catalyst helps to form alkyl thiophene through Friedel-Crafts reaction, which differs from the character of benzene and it is absolutely necessary for the separation and refinement of benzene. But overabundant quantity and higher acid value of [Hmim][HSO4] are more suitable for the side copolymerization of benzene, thiophene and alkene, thereby affecting repeated use of the ionic liquid catalyst([Hmim][HSO4]). In our research, thiophene derivant produced by desulfurization in the coking benzene was used as the polymer to provide the passing channel of the charges. The ionic liquid composition in poor performance after repeated use was made to prepare conductive material (resisting to static electricity) as an "electron-receiving" and "electron-giving" doping agent. The result shows that thiophene derivant after desulfuration in the coking benzene can be used to prepare doping conductive materials.

  20. The pyrolysis of toluene and ethyl benzene

    Science.gov (United States)

    Sokolovskaya, V. G.; Samgin, V. F.; Kalinenko, R. A.; Nametkin, N. S.

    1987-01-01

    The pyrolysis of toluene at 850 to 950 C gave mainly H2, CH4, and benzene; PhEt at 650 to 750 C gave mainly H2, CH4, styrene, benzene, and toluene. The rate constants for PhEt pyrolysis were 1000 times higher than those for toluene pyrolysis; the chain initiation rate constants differed by the same factor. The activation energy differences were 46 kJ/mole for the total reaction and 54 kJ/mole for chain initiation. The chain length was evaluated for the PhEt case (10 + or - 2).

  1. Metabolites of 1,2,3,4-tetrachlorobenzene in monkey urine

    International Nuclear Information System (INIS)

    [14C(U)]-Labeled 1,2,3,4-tetrachlorobenzene was administered orally to squirrel monkeys. Urine was collected from these animals, pooled and analyzed for metabolites by thin-layer chromatography, high-performance liquid chromatography, and gas chromatography-mass spectroscopy. N-Acetyl-s(2,3,4,5-tetrachlorophenyl) cysteine was shown to be the major metabolite and accounted for 85% of the radioactivity found in urine. A minor metabolite was identified at 2,3,4,5-tetrachlorophenol. This study demonstrates for the first time that an N-acetyl cysteine conjugate has been isolated and identified as metabolite of a chlorinated benzene. This pattern of chlorobenzene metabolism is significantly different from the one obtained with the rat and rabbit, where tetrachlorophenols constitute the major metabolites

  2. Recommended sublimation pressure and enthalpy of benzene

    Czech Academy of Sciences Publication Activity Database

    Růžička, K.; Fulem, Michal; Červinka, C.

    2014-01-01

    Roč. 68, Jan (2014), s. 40-47. ISSN 0021-9614 Institutional support: RVO:68378271 Keywords : benzene * vapor pressure * heat capacity * ideal-gas thermodynamic properties * sublimation enthalpy * recommended vapor pressure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.679, year: 2014

  3. 46 CFR 153.1060 - Benzene.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Benzene. 153.1060 Section 153.1060 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Special Cargo Procedures § 153.1060...

  4. Formation of Benzene in the Interstellar Medium

    Science.gov (United States)

    Jones, Brant M.; Zhang, Fangtong; Kaiser, Ralf I.; Jamal, Adeel; Mebel, Alexander M.; Cordiner, Martin A.; Charnley, Steven B.; Crim, F. Fleming (Editor)

    2010-01-01

    Polycyclic aromatic hydrocarbons and related species have been suggested to play a key role in the astrochemical evolution of the interstellar medium, but the formation mechanism of even their simplest building block-the aromatic benzene molecule-has remained elusive for decades. Here we demonstrate in crossed molecular beam experiments combined with electronic structure and statistical calculations that benzene (C6H6) can be synthesized via the barrierless, exoergic reaction of the ethynyl radical and 1,3- butadiene, C2H + H2CCHCHCH2 --> C6H6, + H, under single collision conditions. This reaction portrays the simplest representative of a reaction class in which aromatic molecules with a benzene core can be formed from acyclic precursors via barrierless reactions of ethynyl radicals with substituted 1,3-butadlene molecules. Unique gas-grain astrochemical models imply that this low-temperature route controls the synthesis of the very first aromatic ring from acyclic precursors in cold molecular clouds, such as in the Taurus Molecular Cloud. Rapid, subsequent barrierless reactions of benzene with ethynyl radicals can lead to naphthalene-like structures thus effectively propagating the ethynyl-radical mediated formation of aromatic molecules in the interstellar medium.

  5. Contrastive Analysis of the Raman Spectra of Polychlorinated Benzene: Hexachlorobenzene and Benzene

    Directory of Open Access Journals (Sweden)

    Zhengjun Zhang

    2011-12-01

    Full Text Available Detection of persistent pollutants such as polychlorinated benzene in environment in trace amounts is challenging, but important. It is more difficult to distinguish homologues and isomers of organic pollutantd when present in trace amounts because of their similar physical and chemical properties. In this work we simulate the Raman spectra of hexachlorobenzene and benzene, and figure out the vibration mode of each main peak. The effect on the Raman spectrum of changing substituents from H to Cl is analyzed to reveal the relations between the Raman spectra of homologues and isomers of polychlorinated benzene, which should be helpful for distinguishing one kind of polychlorinated benzene from its homologues and isomers by surface enhanced Raman scattering.

  6. 40 CFR 721.1350 - Benzene, (1-methylethyl)(2-phenylethyl)-.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Benzene, (1-methylethyl)(2-phenylethyl... Substances § 721.1350 Benzene, (1-methylethyl)(2-phenylethyl)-. (a) Chemical substances and significant new uses subject to reporting. (1) The chemical substance identified as benzene,...

  7. 40 CFR 721.1210 - Benzene, (2-chloroethoxy)-.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Benzene, (2-chloroethoxy)-. 721.1210... Substances § 721.1210 Benzene, (2-chloroethoxy)-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, (2-chloroethoxy)- (PMN P-87-1471) is subject...

  8. 40 CFR 721.1187 - Bis(imidoethylene) benzene.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Bis(imidoethylene) benzene. 721.1187... Substances § 721.1187 Bis(imidoethylene) benzene. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance bis(imidoethylene)benzene (PMN P-93-1447) is subject to...

  9. Seed mediated synthesis of highly mono-dispersed gold nanoparticles in the presence of hydroquinone

    Science.gov (United States)

    Kumar, Dhiraj; Mutreja, Isha; Sykes, Peter

    2016-09-01

    Gold nanoparticles (AuNPs) are being studied for several biomedical applications, including drug delivery, biomedical imaging, contrast agents and tumor targeting. The synthesis of nanoparticles with a narrow size distribution is critical for these applications. We report the synthesis of highly mono-dispersed AuNPs by a seed mediated approach, in the presence of tri-sodium citrate and hydroquinone (HQ). AuNPs with an average size of 18 nm were used for the synthesis of highly mono-dispersed nanocrystals of an average size 40 nm, 60 nm, 80 nm and ∼100 nm; but the protocol is not limited to these sizes. The colloidal gold was subjected to UV–vis absorbance spectroscopy, showing a red shift in lambda max wavelength, peaks at 518.47 nm, 526.37 nm, 535.73 nm, 546.03 nm and 556.50 nm for AuNPs seed (18 nm), 40 nm, 60 nm, 80 nm and ∼100 nm respectively. The analysis was consistent with dynamic light scattering and electron microscopy. Hydrodynamic diameters measured were 17.6 nm, 40.8 nm, 59.8 nm, 74.1 nm, and 91.4 nm (size by dynamic light scattering—volume %); with an average poly dispersity index value of 0.088, suggesting mono-dispersity in the size distribution, which was also confirmed by transmission electron microscopy analysis. The advantage of a seed mediated approach is a multi-step growth of nanoparticle size that enables us to control the number of nanoparticles in the suspension, for size ranging from 24.5 nm to 95.8 nm. In addition, the HQ-based synthesis of colloidal nanocrystals allowed control of the particle size and size distribution by tailoring either the number of seeds, amount of gold precursor or reducing agent (HQ) in the final reaction mixture.

  10. Comparative investigation on electrochemical behavior of hydroquinone at carbon ionic liquid electrode, ionic liquid modified carbon paste electrode and carbon paste electrode

    International Nuclear Information System (INIS)

    Ionic liquid, 1-heptyl-3-methylimidazolium hexafluorophosphate (HMIMPF6), has been used to fabricate two new electrodes, carbon ionic liquid electrode (CILE) and ionic liquid modified carbon paste electrode (IL/CPE), using graphite powder mixed with HMIMPF6 or the mixture of HMIMPF6/paraffin liquid as the binder, respectively. The electrochemical behaviors of hydroquinone at the CILE, the IL/CPE and the CPE were investigated in phosphate buffer solution. At all these electrodes, hydroquinone showed a pair of redox peaks. The order of the current response and the standard rate constant of hydroquinone at these electrodes were as follows: CILE > IL/CPE > CPE, while the peak-to-peak potential separation was in an opposite sequence: CILE < IL/CPE < CPE. The results show the superiority of CILE to IL/CPE and CPE, and IL/CPE to CPE in terms of promoting electron transfer, improving reversibility and enhancing sensitivity. The CILE was chosen as working electrode to determine hydroquinone by differential pulse voltammetry, which can be used for sensitive, simple and rapid determination of hydroquinone in medicated skin cosmetic cream

  11. NIOSH (National Institute for Occupational Safety and Health) testimony to DOL (Department of Labor) on OSHA (Occupational Safety and Health Administration) proposed rule for occupational exposure to benzene, by R. Lemen, March 20, 1986

    International Nuclear Information System (INIS)

    The testimony reviewed the history of benzene exposure and the development of recommended exposure limits. Data were reviewed on pharmacokinetics, cytotoxicity, long- and short-term exposures, and skin absorption of benzene. Benzene or its metabolites have been shown to remain in the body for a long period of time following inhalation exposure. Studies in mice revealed exposure-related increases in the frequency of sister chromatid exchanges and micronuclei at all exposure concentrations. Some epidemiological standards relating to the benzene standard were cited. NIOSH recommended that the Permissible Exposure Limit for benzene be reduced to 0.1 ppm as an 8-hour time-weighted average, and that there be a limit on short-term exposures of 1.0ppm for any 15-minute period. These recommendations were made to protect against inhalation of benzene and did not relate to skin absorption. Reports indicated that significant benzene absorption can result among workers exposed to solvents containing about 0.5 percent benzene. It was recommended that steps be taken to eliminate this route of exposure. The use of pressure-demand supplied air respirators with an auxiliary self-contained breathing apparatus or a pressure-demand apparatus was recommended

  12. Enhanced metabolite generation

    Science.gov (United States)

    Chidambaram, Devicharan

    2012-03-27

    The present invention relates to the enhanced production of metabolites by a process whereby a carbon source is oxidized with a fermentative microbe in a compartment having a portal. An electron acceptor is added to the compartment to assist the microbe in the removal of excess electrons. The electron acceptor accepts electrons from the microbe after oxidation of the carbon source. Other transfers of electrons can take place to enhance the production of the metabolite, such as acids, biofuels or brewed beverages.

  13. Pulsed (13)C2-Acetate Protein-SIP Unveils Epsilonproteobacteria as Dominant Acetate Utilizers in a Sulfate-Reducing Microbial Community Mineralizing Benzene.

    Science.gov (United States)

    Starke, Robert; Keller, Andreas; Jehmlich, Nico; Vogt, Carsten; Richnow, Hans H; Kleinsteuber, Sabine; von Bergen, Martin; Seifert, Jana

    2016-05-01

    In a benzene-degrading and sulfate-reducing syntrophic consortium, a clostridium affiliated to the genus Pelotomaculum was previously described to ferment benzene while various sulfate-reducing Deltaproteobacteria and a member of the Epsilonproteobacteria were supposed to utilize acetate and hydrogen as key metabolites derived from benzene fermentation. However, the acetate utilization network within this community was not yet unveiled. In this study, we performed a pulsed (13)C2-acetate protein stable isotope probing (protein-SIP) approach continuously spiking low amounts of acetate (10 μM per day) in addition to the ongoing mineralization of unlabeled benzene. Metaproteomics revealed high abundances of Clostridiales followed by Syntrophobacterales, Desulfobacterales, Desulfuromonadales, Desulfovibrionales, Archaeoglobales, and Campylobacterales. Pulsed acetate protein-SIP results indicated that members of the Campylobacterales, the Syntrophobacterales, the Archaeoglobales, the Clostridiales, and the Desulfobacterales were linked to acetate utilization in descending abundance. The Campylobacterales revealed the fastest and highest (13)C incorporation. Previous experiments suggested that the activity of the Campylobacterales was not essential for anaerobic benzene degradation in the investigated community. However, these organisms were consistently detected in various hydrocarbon-degrading and sulfate-reducing consortia enriched from the same aquifer. Here, we demonstrate that this member of the Campylobacterales is the dominant acetate utilizer in the benzene-degrading microbial consortium. PMID:26846217

  14. Novel oxidative in vitro metabolites of the mycotoxins alternariol and alternariol methyl ether.

    Science.gov (United States)

    Pfeiffer, Erika; Schebb, Nils H; Podlech, Joachim; Metzler, Manfred

    2007-03-01

    The Alternaria toxins alternariol (AOH; 3,7,9-trihydroxy-1-methyl-6H-benzo[c]chromen-6-one) and alternariol methyl ether (AME, 3,7-dihydroxy-9-methoxy-1-methyl-6H-benzo[c]chromen-6-one) are common contaminants of food and feed, but their oxidative metabolism in mammals is as yet unknown. We have therefore incubated AME and AOH with microsomes from rat, human, and porcine liver and analyzed the microsomal metabolites with HPLC and GC-MS/MS. Seven oxidative metabolites of AME and five of AOH were detected. Their chemical structures were derived from their mass spectra using deuterated trimethylsilyl (TMS) derivatives, and from the information obtained from enzymatic methylation. Several of the metabolites were identified by comparison with synthetic reference compounds. AME as well as AOH were monohydroxylated at each of the four possible aromatic carbon atoms and also at the methyl group. In addition, AME was demethylated to AOH and dihydroxylated to a small extent. As the four metabolites arising through aromatic hydroxylation of AME and AOH are either catechols or hydroquinones, the oxidative metabolism of these mycotoxins may be of toxicological significance. PMID:17340575

  15. Simultaneous Detection and Estimation of Catechol, Hydroquinone, and Resorcinol in Binary and Ternary Mixtures Using Electrochemical Techniques

    Directory of Open Access Journals (Sweden)

    Md. Uzzal Hossain

    2015-01-01

    Full Text Available Cyclic voltammetry (CV and differential pulse voltammetry (DPV were performed with a glassy carbon electrode (GCE modified with polyglutamic acid (PGA on the three dihydroxybenzene isomers, catechol (CT, hydroquinone (HQ, and resorcinol (RS. At bare GCE, these isomers exhibited voltammograms with highly overlapped redox peaks that impeded their simultaneous detection in binary and ternary mixtures. On the contrary, at PGA modified GCE binary and ternary mixtures of the dihydroxybenzene isomers showed well-resolved redox peaks in both CV and DPV experiments. This resolving ability of PGA modified GCE proves its potential to be exploited as an electrochemical sensor for the simultaneous detection of these isomers.

  16. Exogenous ochronosis after prolonged use of topical hydroquinone (2% in a 50-year-old Indian female

    Directory of Open Access Journals (Sweden)

    Vijay Gandhi

    2012-01-01

    Full Text Available Ochronosis is a rare disease characterized by speckled and diffuse pigmentation symmetrically over the face, neck, and photo-exposed areas. It is characterized histologically by banana-shaped ochre-colored deposits in the dermis. It can present in exogenous or endogenous form. We report a case of exogenous ochronosis in a 50-year-old Indian woman after prolonged use of topical hydroquinone which is a rare complication with a commonly used drug which is available over the counter.

  17. A comparative study of the efficacy of 4% hydroquinone vs 0.75% Kojic acid cream in the treatment of facial melasma

    Directory of Open Access Journals (Sweden)

    Rochelle C Monteiro

    2013-01-01

    Full Text Available Background: Melasma is a common acquired cause of facial hyperpigmentation seen predominantly among females with significant psychological and social impact. It is often recalcitrant to treatment. Several topical hypopigmenting agents have been used to combat melasma. Hydroquinone and Kojic Acid are well established monotherapeutic agents for treating melasma. Objectives: This study focuses mainly on the efficacy of once daily application of 4% Hydroquinone and 0.75% Kojic Acid cream (containing 0.75% Kojic acid and 2.5% vitamin C so as to determine an effective modality of treatment for facial melasma. Materials and Methods: A total number of 60 patients with facial melasma attending the Out-patient department of Dermatology, Venerology and Leprosy, Fr. Muller Medical College Hospital, Mangalore from Oct 2008-April 2010 were studied. Patients were allocated alternately to group A and group B. Group A patients received 4% Hydroquinone cream and group B patient received a Kojic Acid cream (which contained 0.75% Kojic acid and 2.5% vitamin C and were advised to apply topically once daily at night. Patients were followed up on 4 th , 8 th and 12 th week. At each visit side effects were noted and clinical response to treatment was calculated using the MASI score. Statistical Methods: Chi square test, student ′t′ test. Results: At the 4 th week post treatment evaluation, facial hyperpigmentation responded early to 4% Hydroquinone cream than to 0.75% Kojic Acid cream. At the end of 12 week treatment period, 4% Hydroquinone cream had an overall superiority to 0.75% Kojic Acid cream as a topical hypopigmenting agent. Conclusion: The results of the study show that 4% Hydroquinone cream is a better topical hypopigmenting agent with rapid rate of clinical improvement when compared to 0.75% Kojic Acid cream.

  18. Nonlinear diffusion in Acetone-Benzene Solution

    CERN Document Server

    Obukhovsky, Vjacheslav V

    2010-01-01

    The nonlinear diffusion in multicomponent liquids under chemical reactions influence has been studied. The theory is applied to the analysis of mass transfer in a solution of acetone-benzene. It has been shown, that the creation of molecular complexes should be taken into account for the explanation of the experimental data on concentration dependence of diffusion coefficients. The matrix of mutual diffusivities has been found and effective parameters of the system have been computed.

  19. Accumulation of chlorinated benzenes in earthworms

    Energy Technology Data Exchange (ETDEWEB)

    Beyer, W.N. [Patuxent Wildlife Research Center, Laurel, MD (United States)

    1996-12-31

    Chlorinated benzenes are widespread in the environment. Hexachlorobenzene, pentachlorobenzene and all isomers of dichlorobenzenes, trichlorobenzenes, and tetrachlorobenzenes, have been detected in fish, water, and sediments from the Great Lakes. They probably entered the water as leachates from chemical waste dumps and as effluents from manufacturing. Hexachlorobenzene and pentachlorobenzene are commonly present in Herring gull (Larus argentatus) eggs from the Great Lakes, and some of the isomers of trichlorobenzene and tetrachlorobenzene are occasionally detected at low concentrations. Hexachlorobenzene, which was formerly used as a fungicide, has been the most thoroughly studied chlorinated benzene, and has been detected in many species. Its use as a fungicide in the United States was canceled in 1984. Since about 1975 hexachlorobenzene has been formed mainly in the production of chlorinated solvents. It is highly persistent in the environment and some species are poisoned by hexachlorobenzene at very low chronic dietary exposures. As little as 1 ppm in the diet of mink (Mustela vison) reduced the birth weights of young, and 5 ppm in the diet of Japanese quail (Coturnix coturnix japonica) caused slight liver damage. This paper describes a long-term (26 wk) experiment relating the concentrations of chlorinated benzenes in earthworms to length of exposure and three 8 wk experiments relating concentration to the concentration in soil the soil organic matter content, and the degree of chlorination. 20 refs., 3 figs., 1 tab.

  20. PROCESS SIMULATION OF BENZENE SEPARATION COLUMN OF LINEAR ALKYL BENZENE (LABPLANT

    Directory of Open Access Journals (Sweden)

    Zaid A. AbdelRahman

    2013-05-01

    Full Text Available       CHEMCAD process simulator was used for the analysis of existing benzene separation column in LAB plant(Arab Detergent Company/Beiji-Iraq.         Simulated column performance curves were constructed. The variables considered in this study are the thermodynamic model option, top and bottom temperatures, feed temperature, feed composition & reflux ratio. Also simulated columns profiles for the temperature, vapor & liquid flow rates compositions, were constructed. Four different thermodynamic models options (SRK, TSRK, PR, and ESSO were used, affecting the results within 1-25% variation for the most cases.            For Benzene Column (32 real stages, feed stage 14, the simulated results show that bottom temperature above 200 oC the weight fractions of top components, except benzene, increases sharply, where as benzene top weight fraction decreasing sharply. Also, feed temperature above 180 oC  shows same trends. The column profiles remain fairly constant from tray 3 (immediately below condenser to tray 10 (immediately above feed and from tray 15 (immediately below feed to tray 25 (immediately above reboiler. Simulation of the benzene separation column in LAB production plant using CHEMCAD simulator, confirms the real plant operation data. The study gives evidence about a successful simulation with CHEMCAD.

  1. At-line benzene monitor for measuring benzene in precipitate hydrolysis aqueous

    Energy Technology Data Exchange (ETDEWEB)

    Jenkins, W.J.

    1992-10-14

    A highly accurate and repeatable at-line benzene monitor (ALBM) has been developed to measure the benzene concentration in precipitate hydrolysis aqueous (PHA) in the DWPF. This analyzer was conceived and jointly developed within SRTC by the Analytical Development and the Defense Waste Process Technology Sections with extensive support from the Applied Statistics Group and the TNX Operations Section. It is recommended that an ALBM specifically adapted to DWPF analytical requirements be used to measure benzene in PHA; calibrations be performed using a 10% methanol solution matrix (for standard stability); and based on experience gained in development at TNX, the services of ADS and ASG be employed to both adapt the ALBM to DWPF requirements and develop statistical control procedures.

  2. At-line benzene monitor for measuring benzene in precipitate hydrolysis aqueous

    International Nuclear Information System (INIS)

    A highly accurate and repeatable at-line benzene monitor (ALBM) has been developed to measure the benzene concentration in precipitate hydrolysis aqueous (PHA) in the DWPF. This analyzer was conceived and jointly developed within SRTC by the Analytical Development and the Defense Waste Process Technology Sections with extensive support from the Applied Statistics Group and the TNX Operations Section. It is recommended that an ALBM specifically adapted to DWPF analytical requirements be used to measure benzene in PHA; calibrations be performed using a 10% methanol solution matrix (for standard stability); and based on experience gained in development at TNX, the services of ADS and ASG be employed to both adapt the ALBM to DWPF requirements and develop statistical control procedures

  3. Benzene exposure: An overview of monitoring methods and their findings

    OpenAIRE

    Weisel, Clifford P.

    2010-01-01

    Benzene has been measured throughout the environment and is commonly emitted in several industrial and transportation settings leading to widespread environmental and occupational exposures. Inhalation is the most common exposure route but benzene rapidly penetrates the skin and can contaminant water and food resulting in dermal and ingestion exposures. While less toxic solvents have been substituted for benzene, it still is a component of petroleum products, including gasoline, and is a trac...

  4. 40 CFR 80.1238 - How is a refinery's or importer's average benzene concentration determined?

    Science.gov (United States)

    2010-07-01

    ... average benzene concentration determined? 80.1238 Section 80.1238 Protection of Environment ENVIRONMENTAL... Benzene Gasoline Benzene Requirements § 80.1238 How is a refinery's or importer's average benzene concentration determined? (a) The average benzene concentration of gasoline produced at a refinery or...

  5. Physiological and phylogenetic characterization of a stable benzene-degrading, chlorate-reducing microbial community

    NARCIS (Netherlands)

    Weelink, S.A.B.; Tan, N.C.G.; Broeke, H. ten; Doesburg, W. van; Langenhoff, A.A.M.; Gerritse, J.; Stams, A.J.M.

    2007-01-01

    A stable anoxic enrichment culture was obtained that degraded benzene with chlorate as an electron acceptor. The benzene degradation rate was 1.65 mM benzene per day, which is similar to reported aerobic benzene degradation rates but 20-1650 times higher than reported for anaerobic benzene degradati

  6. Green and controllable strategy to fabricate well-dispersed graphene–gold nanocomposite film as sensing materials for the detection of hydroquinone and resorcinol with electrodeposition

    International Nuclear Information System (INIS)

    Highlights: ► We reported firstly green and controllable strategy to fabricate graphene–gold composite. ► The strategy provides control over reaction parameters and excellent repeatability. ► The composite offers faster electron transfer than pure graphene and gold nanoparticles. ► The composite was used to fabricate sensor for detection of hydroquinone and resorcinol. ► The sensor displays the best sensitivity for hydroquinone and resorcinol up to now. - Abstract: The paper described a green and controllable strategy to fabricate well-dispersed graphene–gold nanocomposite film. To prepare graphene–gold nanocomposite film, graphene and gold nanoparticles were alternately electrodeposited on the surface of glassy carbon electrode. Since electrochemical technique offers control over reaction parameters and excellent repeatability, the amounts of graphene and gold nanoparticles for the each layer can be pre-determined by controlling concentrations of graphene oxide and chlorauric acid. The as-prepared graphene–gold nanocomposite film was characterized by infrared spectrum, scanning electron microscope, Raman spectrum and X-ray diffraction, and its electrocatalytic activity was estimated by Laviron's model. The apparent heterogeneous electron transfer rate constant of 37.67 ± 0.19 cm s−1 was obtained, indicating fast electron transfer of Fe(CN)64− to the electrode. Further, the film was investiaged as sensing materials for synchronously detection of hydroquinone and resorcinol. When the cencentrations are in the ranges of 1.6 × 10−8 to 1.2 × 10−4 mol l−1 for hydroquinone and 1.0 × 10−8 to 2 × 10−6 mol l−1 for resorcinol, differential pulse voltammetric peak current of the sensor linearly increases. The sensitivities of differential pulse voltammetric response are 30.5 μA μM−1 cm−2 for hydroquinone and 117.83 μA μM−1 cm−2 for resorcinol. The detection limits were found to be 5.2 × 10−9 mol l−1 for hydroquinone and

  7. Metabolomics for Secondary Metabolite Research

    Directory of Open Access Journals (Sweden)

    Eriko Takano

    2013-11-01

    Full Text Available Metabolomics, the global characterization of metabolite profiles, is becoming an increasingly powerful tool for research on secondary metabolite discovery and production. In this review we discuss examples of recent technological advances and biological applications of metabolomics in the search for chemical novelty and the engineered production of bioactive secondary metabolites.

  8. Hydroquinone based sulfonated poly (arylene ether sulfone copolymer as proton exchange membrane for fuel cell applications

    Directory of Open Access Journals (Sweden)

    V. Kiran

    2015-12-01

    Full Text Available Synthesis of sulfonated poly (arylene ether sulfone copolymer by direct copolymerization of 4,4'-bis(4-hydroxyphenyl valeric acid, benzene 1,4-diol and synthesized sulfonated 4,4'-difluorodiphenylsulfone and its characterization by using FTIR (Fourier Transform Infrared and NMR (Nuclear Magnetic Resonance spectroscopic techniques have been performed. The copolymer was subsequently cross-linked with 4, 4!(hexafluoroisopropylidenediphenol epoxy resin by thermal curing reaction to synthesize crosslinked membranes. The evaluation of properties showed reduction in water and methanol uptake, ion exchange capacity, proton conductivity with simultaneous enhancement in oxidative stability of the crosslinked membranes as compared to pristine membrane. The performance of the membranes has also been evaluated in terms of thermal stability, morphology, mechanical strength and methanol permeability by using Thermo gravimetric analyzer, Differential scanning calorimetery, Atomic force microscopy, XPERT-PRO diffractometer, universal testing machine and diffusion cell, respectively. The results demonstrated that the crosslinked membranes exhibited high thermal stability with phase separation, restrained crystallinity, acceptable mechanical properties and methanol permeability. Therefore, these can serve as promising proton exchange membranes for fuel cell applications.

  9. Hydroquinone Resin Induced Carbon Nanotubes on Ni Foam As Binder-Free Cathode for Li-O2 Batteries.

    Science.gov (United States)

    Zhu, Qian-Cheng; Du, Fei-Hu; Xu, Shu-Mao; Wang, Zong-Kai; Wang, Kai-Xue; Chen, Jie-Sheng

    2016-02-17

    In this work, hydroquinone resin was used to grow carbon nanotubes directly on Ni foam. The composites were obtained via a simple carbonization method, which avoids using the explosive gaseous carbon precursors that are usually applied in the chemical vapor deposition method. When evaluated as cathode for Li-O2 batteries, the binder-free structure showed enhanced ORR/OER activities, thus giving a high rate capability (12690 mAh g(-1) at 200 mA g(-1) and 3999 mAh g(-1) at 2000 mA g(-1)) and outstanding long-term cycling stability (capacity limited 2000 mAh g(-1), 110 cycles at 200 mA g(-1)). The excellent battery performance provides new insights into designing a low-cost and high-efficiency cathode for Li-O2 batteries. PMID:26720145

  10. Screening for occupational vitiligo in workers exposed to hydroquinone monomethyl ether and to paratertiary-amyl-phenol

    Energy Technology Data Exchange (ETDEWEB)

    O' Sullivan, J.J.; Stevenson, C.J.

    1981-11-01

    Two men reported previously with vitiligo after occupational exposure to hydroquinone monomethyl ether (HMME) have been reviewed after eight years. Repigmentation of significant degree was found in one man and of limited degree in the other. One hundred and sixty-nine men in the same works have been screened with Wood's light for evidence of vitiligo. No cases were found in the 148 men exposed to HMME (colleagues who screened 100 men exposed to HMME in two other factories also found no case) or in the 129 who had been exposed to paratertiary-amyl-phenol. Loss of light reflection on Wood's light examination was observed in 13 men due to scars or to other skin disorders.

  11. Benzene as a Chemical Hazard in Processed Foods

    Directory of Open Access Journals (Sweden)

    Vânia Paula Salviano dos Santos

    2015-01-01

    Full Text Available This paper presents a literature review on benzene in foods, including toxicological aspects, occurrence, formation mechanisms, and mitigation measures and analyzes data reporting benzene levels in foods. Benzene is recognized by the IARC (International Agency for Research on Cancer as carcinogenic to humans, and its presence in foods has been attributed to various potential sources: packaging, storage environment, contaminated drinking water, cooking processes, irradiation processes, and degradation of food preservatives such as benzoates. Since there are no specific limits for benzene levels in beverages and food in general studies have adopted references for drinking water in a range from 1–10 ppb. The presence of benzene has been reported in various food/beverage substances with soft drinks often reported in the literature. Although the analyses reported low levels of benzene in most of the samples studied, some exceeded permissible limits. The available data on dietary exposure to benzene is minimal from the viewpoint of public health. Often benzene levels were low as to be considered negligible and not a consumer health risk, but there is still a need of more studies for a better understanding of their effects on human health through the ingestion of contaminated food.

  12. The excited state antiaromatic benzene ring: a molecular Mr Hyde?

    Science.gov (United States)

    Papadakis, Raffaello; Ottosson, Henrik

    2015-09-21

    The antiaromatic character of benzene in its first ππ* excited triplet state (T1) was deduced more than four decades ago by Baird using perturbation molecular orbital (PMO) theory [J. Am. Chem. Soc. 1972, 94, 4941], and since then it has been confirmed through a range of high-level quantum chemical calculations. With focus on benzene we now first review theoretical and computational studies that examine and confirm Baird's rule on reversal in the electron count for aromaticity and antiaromaticity of annulenes in their lowest triplet states as compared to Hückel's rule for the ground state (S0). We also note that the rule according to quantum chemical calculations can be extended to the lowest singlet excited state (S1) of benzene. Importantly, Baird, as well as Aihara [Bull. Chem. Soc. Jpn. 1978, 51, 1788], early put forth that the destabilization and excited state antiaromaticity of the benzene ring should be reflected in its photochemical reactivity, yet, today these conclusions are often overlooked. Thus, in the second part of the article we review photochemical reactions of a series of benzene derivatives that to various extents should stem from the excited state antiaromatic character of the benzene ring. We argue that benzene can be viewed as a molecular "Dr Jekyll and Mr Hyde" with its largely unknown excited state antiaromaticity representing its "Mr Hyde" character. The recognition of the "Jekyll and Hyde" split personality feature of the benzene ring can likely be useful in a range of different areas. PMID:25960203

  13. An efficient synthesis of substituted benzene-1,2-dicarboxaldehydes

    Institute of Scientific and Technical Information of China (English)

    ZHU Peter C; WANG Dei-Haw; LU Kaitao; MANI Neelakandha

    2007-01-01

    Substituted-benzene-1,2-dicarbaldehydes were synthesized by the reaction of substituted-1,2-bis (dibromomethyl) benzenes with fuming sulfuric acid, followed by hydrolysis, The yields were significantly improved by introducing solid sodium bicarbonate into the reaction mixture before hydrolysis and workup.

  14. An efficient synthesis of substituted benzene-1,2-dicarboxaldehydes

    Institute of Scientific and Technical Information of China (English)

    ZHU; Peter; C; WANG; Der-Haw; MANI; Neelakandha

    2007-01-01

    Substituted-benzene-1,2-dicarbaldehydes were synthesized by the reaction of substituted-1,2-bis(dibromomethyl) benzenes with fuming sulfuric acid,followed by hydrolysis. The yields were signifi-cantly improved by introducing solid sodium bicarbonate into the reaction mixture before hydrolysis and workup.

  15. 1,4-Bis[(2-pyridylethyliminomethyl]benzene

    Directory of Open Access Journals (Sweden)

    Haleden Chiririwa

    2011-04-01

    Full Text Available In the title compound, C22H22N4, the centroid of the benzene ring is located on an inversion centre. The dihedral angle between the benzene and pyridine rings is 10.94 (5°. The crystal structure displays weak intermolecular C—H...N hydrogen bonding and C—H...π interactions.

  16. [Update on benzene: from industrial toxicant to environmental carcinogen].

    Science.gov (United States)

    Manno, Maurizio

    2013-01-01

    Benzene, an industrial chemical myelotoxic at high doses in workers, is now an almost ubiquitous pollutant. It is also a no-threshold genotoxic carcinogen causing acute leukemia and other lymphoaematological tumours. Although its mechanism of action has not been fully clarified, benzene toxicity and carcinogenicity depend on metabolic activation. Polymorphism of activating and detoxifying enzymes (CYP, GST, NQO1) may be critical, therefore, in modulating individual susceptibility to benzene. Further uncertainty factors in assessing low level benzene exposure are the limited sensitivity and specificity of most exposure biomarkers, the frequent coexposure to other volatile organic chemicals (VOC), and the presence of non occupational sources of exposure, such as cigarette smoke and veicular traffic. The aim of this presentation is to introduce the main current critical issues in the risk assessment and the biological monitoring of occupational exposure to benzene at low doses. PMID:24303704

  17. Air pollution monitoring in Como urban areas. Benzene

    International Nuclear Information System (INIS)

    This work presents the results of a physical - statistical analysis of concentrations of benzene, measured in the Como Center station from 1996 to 1999. The analysis, conducted by means of the development, by steps, of a multifactorial linear regression model, permitted to find an annual trend of benzene, independently from the influence of meteorologicals variables. It has been seen a decrease of concentrations of benzene, from 1997 to 1999, that may be correlate to a decrease of tenor of benzene in the petrol. At the same time, the results of the model permit to understand the role and the relative weight of different climatic factors on the concentrations of benzene. It has been investigated the presence of daily, weekly and seasonal trend, too

  18. Catalytic conversion of alcohols to hydrocarbons with low benzene content

    Energy Technology Data Exchange (ETDEWEB)

    Narula, Chaitanya K.; Davison, Brian H.; Keller, Martin

    2016-09-06

    A method for converting an alcohol to a hydrocarbon fraction having a lowered benzene content, the method comprising: converting said alcohol to a hydrocarbon fraction by contacting said alcohol, under conditions suitable for converting said alcohol to said hydrocarbon fraction, with a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon fraction, and contacting said hydrocarbon fraction with a benzene alkylation catalyst, under conditions suitable for alkylating benzene, to form alkylated benzene product in said hydrocarbon fraction. Also described is a catalyst composition useful in the method, comprising a mixture of (i) a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon, and (ii) a benzene alkylation catalyst, in which (i) and (ii) may be in a mixed or separated state. A reactor for housing the catalyst and conducting the reaction is also described.

  19. Catalytic conversion of alcohols to hydrocarbons with low benzene content

    Energy Technology Data Exchange (ETDEWEB)

    Narula, Chaitanya K.; Davison, Brian H.; Keller, Martin

    2016-03-08

    A method for converting an alcohol to a hydrocarbon fraction having a lowered benzene content, the method comprising: converting said alcohol to a hydrocarbon fraction by contacting said alcohol, under conditions suitable for converting said alcohol to said hydrocarbon fraction, with a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon fraction, and contacting said hydrocarbon fraction with a benzene alkylation catalyst, under conditions suitable for alkylating benzene, to form alkylated benzene product in said hydrocarbon fraction. Also described is a catalyst composition useful in the method, comprising a mixture of (i) a metal-loaded zeolite catalyst catalytically active for converting said alcohol to said hydrocarbon, and (ii) a benzene alkylation catalyst, in which (i) and (ii) may be in a mixed or separated state. A reactor for housing the catalyst and conducting the reaction is also described.

  20. Competitive Nitration of Benzene-Fluorobenzene and Benzene-Toluene Mixtures: Orientation and Reactivity Studies Using HPLC

    Science.gov (United States)

    Blankespoor, Ronald L.; Hogendoorn, Stephanie; Pearson, Andrea

    2007-01-01

    The reactivity and orientation effects of a substituent are analyzed by using HPLC to determine the competitive nitration of the benzene-toluene and benzene-fluorobenzene mixtures. The results have shown that HPLC is an excellent instrumental method to use in analyzing these mixtures.

  1. A Quantum Monte Carlo Study of mono(benzene)TM and bis(benzene)TM Systems

    CERN Document Server

    Bennett, M Chandler; Mitas, Lubos

    2016-01-01

    We present a study of mono(benzene)TM and bis(benzene)TM systems, where TM={Mo,W}. We calculate the binding energies by quantum Monte Carlo (QMC) approaches and compare the results with other methods and available experiments. The orbitals for the determinantal part of each trial wave function were generated from several types of DFT in order to optimize for fixed-node errors. We estimate and compare the size of the fixed-node errors for both the Mo and W systems with regard to the electron density and degree of localization in these systems. For the W systems we provide benchmarking results of the binding energies, given that experimental data is not available.

  2. Kinetic modeling and determination role of sono/photo nanocatalyst-generated radical species on degradation of hydroquinone in aqueous solution.

    Science.gov (United States)

    Rahimi, Sajad; Ayati, Bita; Rezaee, Abbas

    2016-06-01

    Experimental findings of sonophotocatalytic process were used in degradation of hydroquinone to assess kinetic modeling and determine the effect of various active radical species. First, the effects of three photocatalytic, sonocatalytic, and sonophotocatalytic processes were studied for hydroquinone removal to determine kinetic constants and calculate the activation energy of reactions, and then the selected process was evaluated to determine active radical species. The reactor was composed of two parts, one included ultrasonic probe (sonocatalytic part) with powers 22, 80, and 176 W and the second part was the location of UV lamp (photocatalytic part) with tubular flow and power 15 W. After three systems were examined and the efficient system was selected, the role of different active species such as hydroxyl radical (OH(·)), superoxide radical (O2 (·-)), hole (h(+)), electrons (e (-)), and single oxygen molecule ((1)O2) and contribution of each of them were determined in hydroquinone degradation. According to tests, the results of this study showed that sonophotocatalytic integrated method as selected system among three systems studied followed the first-order equation for hydroquinone degradation and active hydroxyl species with 45 % and electron and hole with 15 and 10 %, respectively, had the highest and lowest contributions to conversion of hydroquinone. The findings showed that dissolved oxygen increases the capability of active radical formation so that 28.2 % of hydroquinone removal was increased under aeration compared to without aeration. Also, removal efficiency decreased 62 % with N2 injection due to the withdrawal of oxygen from the sample. By adding 25 Mm of sodium azide (NaN3) to stock solution, 46.5 % reduction was developed because single oxygen ((1)O2) played the role of an active species. The advantages of integrated sonocatalytic and photocatalytic method are the generation of active radical species with more variety and ultimately

  3. Crude Oil Metabolites in Groundwater at Two Spill Sites

    Science.gov (United States)

    Bekins, Barbara A.; Cozzarelli, Isabelle M.; Erickson, Melinda L.; Steenson, Ross; Thorn, Kevin A.

    2016-01-01

    Two groundwater plumes in north central Minnesota with residual crude oil sources have 20 to 50 mg/L of nonvolatile dissolved organic carbon (NVDOC). These values are over 10 times higher than benzene and two to three times higher than Diesel Range Organics in the same wells. On the basis of previous work, most of the NVDOC consists of partial transformation products from the crude oil. Monitoring data from 1988 to 2015 at one of the sites located near Bemidji, MN show that the plume of metabolites is expanding toward a lakeshore located 335 m from the source zone. Other mass balance studies of the site have demonstrated that the plume expansion is driven by the combined effect of continued presence of the residual crude oil source and depletion of the electron accepting capacity of solid phase iron oxide and hydroxides on the aquifer sediments. These plumes of metabolites are not covered by regulatory monitoring and reporting requirements in Minnesota and other states. Yet, a review of toxicology studies indicates that polar metabolites of crude oil may pose a risk to aquatic and mammalian species. Together the results suggest that at sites where residual sources are present, monitoring of NVDOC may be warranted to evaluate the fates of plumes of hydrocarbon transformation products.

  4. Production of Metabolites

    DEFF Research Database (Denmark)

    2011-01-01

    A recombinant micro-organism such as Saccharomyces cerevisiae which produces and excretes into culture medium a stilbenoid metabolite product when grown under stilbenoid production conditions, which expresses in above native levels a ABC transporter which transports said stilbenoid out of said...... micro-organism cells to the culture medium. The genome of the Saccharomyces cerevisiae produces an auxotrophic phenotype which is compensated by a plasmid which also expresses one or more of said enzymes constituting said metabolic pathway producing said stilbenoid, an expression product of the plasmid...

  5. [Antiviral properties of basidiomycetes metabolites].

    Science.gov (United States)

    Avtonomova, A V; Krasnopolskaya, L M

    2014-01-01

    The data on the antiviral action of the Ganoderma lucidum, Lentinus edodes, Grifola frondosa, Agaricus brasiliensis and other basidiomycetes metabolites are summurized. The metabolites of these species of basidiomycetes exhibit a direct antiviral effect on herpes simplex virus types I and II, human immunodeficiency virus (HIV), hepatitis B virus, vesicular stomatitis virus, influenza virus, Epstein-Barr virus, and others. Moreover, metabolites of basidiomycetes increased antiviral immunity. PMID:25975107

  6. Using a Hydroquinone/Tretinoin-based Skin Care System Before and After Electrodesiccation and Curettage of Superficial Truncal Basal Cell Carcinoma: A Multicenter, Randomized, Investigator-blind, Controlled Study of Short-term Healing

    OpenAIRE

    David, Pariser; James, Spencer; Brian, Berman; Suzanne, Bruce; Lisa, Parr; Kenneth, Gross

    2009-01-01

    Objective: To evaluate the efficacy and tolerability of using a 4% hydroquinone/0.05% tretinoin skin care system compared with standard treatment of cleanser plus healing ointment to enhance aesthetic outcomes resulting from electrodesiccation and curettage treatment for superficial truncal basal cell carcinomas. Design: Multicenter, investigator-masked, randomized, parallel-group study. Patients received either the hydroquinone/tretinoin system or the standard treatment twice daily for three...

  7. Benzene conversion by manganese dioxide assisted silent discharge plasma

    Institute of Scientific and Technical Information of China (English)

    LU Bin; JI Min; YU Xin; FENG Tao; YAO Shuiliang

    2007-01-01

    Non-thermal plasma technologies have shown their promising potential specially for the low concentration of volatile organic compound control in indoor air in recent years.But it is also high energy consuming.So,to improve the energy efficiency,adding catalysts which enhance the plasma chemical reactions to plasma reactors may be a good selection.Therefore,in this study the manganese dioxide assisted silent discharge plasma was developed for benzene conversion at a relatively high energy efficiency.The results show that MnO2 could promote complete oxidation of benzene with O2 and O3 produced in the plasma discharge zone.The energy efficiency of benzene conversion with MnO2 was two folds as much as that without catalysts.It was also found that the site of MnO2 in the reactor and the energy density had effects on benzene conversion.While the energy density was lower than 48 J/L,benzene conversion decreased with the increase in the distance between MnO2 bed and the plasma discharge zone.Whereas when the energy density was higher than 104 J/L,benzene conversion had an optimal value that was governed by the distance between MnO2 bed and the plasma discharge zone.The mechanism of benzene oxidation in plasma discharges and over MnO2 is discussed in detail.

  8. Benefits of using a hydroquinone/tretinoin skin care system in patients undergoing intense pulsed light therapy for photorejuvenation: a placebo-controlled study.

    Science.gov (United States)

    Woodhall, Katrina E; Goldman, Mitchel P; Gold, Michael H; Biron, Julie

    2009-09-01

    A hydroquinone/tretinoin (HQ/tret) skin care system designed for use with non-surgical facial rejuvenation procedures has recently become available. In this observer-masked study, 36 patients with moderate-to-severe wrinkling of the skin around the eyes and lips were randomly assigned to use either the 4% hydroquinone/0.05% tretinoin skin care system or placebo products, each day for 90 days. In addition, all patients received intense pulsed light (IPL) treatment on days 30 and 60. At day 90, > or = 75% overall improvement was reported in 72% and 19% of patients in the HQ/tret + IPL group and the placebo + IPL group, respectively. HQ/tret + IPL was also associated with significantly lower mean hyperpigmentation scores at days 30, 60 and 90 (P IPL. Adjunctive use of the HQ/tret system enhances the improvements in facial skin achieved with IPL treatment. PMID:19746679

  9. Hydroquinone-O,O'-diacetic acid ('Q-linker') as a replacement for succinyl and oxalyl linker arms in solid phase oligonucleotide synthesis.

    OpenAIRE

    Pon, R T; Yu, S.

    1997-01-01

    When hydroquinone-O,Ooffiacetic acid is used as a linker arm in solid phase oligonucleotide synthesis, the time for NH4OH cleavage of oligodeoxy- or oligoribonucleotides is reduced to only 2 min. This allows increased productivity on automated DNA synthesizers without requiring any other modifications to existing reagents or synthesis and deprotection methods. The Q-linker may also be rapidly cleaved by milder reagents such as 5% NH4OH, potassium carbonate, anhydrous ammonia, t-butylamine or ...

  10. Open-Label Treatment of Moderate or Marked Melasma with a 4% Hydroquinone Skin Care System Plus 0.05% Tretinoin Cream

    OpenAIRE

    Gold, Michael; Rendon, Marta; Dibernardo, Barry; Bruce, Suzanne; Lucas-Anthony, Chere; Watson, Joanne

    2013-01-01

    Objective: To evaluate treating epidermal melasma using a 4% hydroquinone skin care system plus tretinoin 0.05% cream. Design: Multicenter open-label study with all patients receiving above-mentioned treatment for up to 24 weeks. Setting: Private dermatology and plastic surgery clinics and clinical research facilities. Participants: Thirty-seven adult females with moderate or marked epidermal melasma, melasma pigmentation of mild-to-marked intensity and Fitzpatrick skin type III to VI. Measur...

  11. Effect of Hydroquinone Plus Neodymium-Doped Yttrium Aluminium Garnet Laser With and Without CO2 Fractional Laser on Resistant Dermal Melasma

    Directory of Open Access Journals (Sweden)

    Zamanian

    2015-06-01

    Full Text Available Background The use of different types of lasers in the treatment of refractory melasma is still controversial. The present study was designed according to previous studies and used a combination of treatments. Objectives The purpose of this study was to compare Q-switched (QS neodymium-doped yttrium aluminium garnet (Nd: YAG laser and hydroquinone with or without CO2 fractional laser in refractory melasma. Patients and Methods Seventeen patients with refractory melasma, in a split-face randomized trial, received topical hydroquinone and Nd: YAG laser treatment on one half of their face and topical hydroquinone, Nd: YAG laser and CO2 fractional laser on the other half of their face. The patients were then assessed by Melasma area and severity index (MASI over 12 weeks in three treatment sessions with an interval of three to four weeks. Results Seventeen patients with melasma (14 females and three males with mean (± SD age of 38.47 (± 6.29 years (range 29 - 53 were included in this study. The only side effect for the Nd: YAG treatment was erythema observed in two cases (11.8%. The mean MASI scores decreased significantly after six weeks for both therapies. Also, a significant reduction was observed in the mean MASI scores from week six till the end of the study. Controlling for the effect of “MASI score at baseline”, the mean MASI score was significantly lower on the side treated with Nd:YAG + CO2 fractional laser in comparison with the Nd: YAG laser. Conclusions Our study showed that the triple therapy of ND: YAG and ND: YAG + CO2 fractional and hydroquinone cream had high efficiency and low morbidity compared to twofold treatment with ND: YAG and ND: YAG + CO2 fractional.

  12. Effect of Hydroquinone Plus Neodymium-Doped Yttrium Aluminium Garnet Laser With and Without CO2 Fractional Laser on Resistant Dermal Melasma

    OpenAIRE

    Zamanian; Behrangi; Ghafarpour; Mehran; Espahbodi; Hoseinzade Fakhim; Azizian

    2015-01-01

    Background The use of different types of lasers in the treatment of refractory melasma is still controversial. The present study was designed according to previous studies and used a combination of treatments. Objectives The purpose of this study was to compare Q-switched (QS) neodymium-doped yttrium aluminium garnet (Nd: YAG) laser and hydroquinone with or without CO2 fractional laser in refractory melasma. ...

  13. Hydroxylation of yohimbine in superacidic media: one-step access to human metabolites 10 and 11-hydroxyyohimbine.

    Science.gov (United States)

    Duflos, A; Redoules, F; Fahy, J; Jacquesy, J C; Jouannetaud, M P

    2001-02-01

    Two major human metabolites of yohimbine (1), 10- and 11-hydroxyyohimbine (2 and 3), were prepared by direct hydroxylation of 1 under superacidic conditions. In this medium, the four positions of the benzene part of yohimbine were hydroxylated and the corresponding monohydroxylated compounds (2-5) were isolated. The structures of 2-5 were elucidated by spectroscopic methods including 1D and 2D NMR techniques. PMID:11429998

  14. 40 CFR 80.1285 - How does a refiner apply for a benzene baseline?

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 16 2010-07-01 2010-07-01 false How does a refiner apply for a benzene... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1285 How does a refiner apply for a benzene baseline? (a) A benzene...

  15. 40 CFR 80.1220 - What are the implementation dates for the gasoline benzene program?

    Science.gov (United States)

    2010-07-01

    ... the gasoline benzene program? 80.1220 Section 80.1220 Protection of Environment ENVIRONMENTAL... Benzene General Information § 80.1220 What are the implementation dates for the gasoline benzene program? (a) Benzene standard. (1) For the annual averaging period beginning January 1, 2011, and for...

  16. Toluhydroquinone, the secondary metabolite of marine algae symbiotic microorganism, inhibits angiogenesis in HUVECs.

    Science.gov (United States)

    Kim, Nan-Hee; Jung, Hyun-Il; Choi, Woo-Suk; Son, Byeng-Wha; Seo, Yong-Bae; Choi, Jae Sue; Kim, Gun-Do

    2015-03-01

    Angiogenesis, the growth of new blood vessels from the existing ones, occurs during embryo development and wound healing. However, most malignant tumors require angiogenesis for their growth and metastasis as well. Therefore, inhibition of angiogenesis has been focused as a new strategy of cancer therapies. To treat cancer, there are marine microorganism-derived secondary metabolites developed as chemotherapeutic agents. In this study, we used toluhydroquinone (2-methyl-1,4-hydroquinone), one of the secondary metabolites isolated from marine algae symbiotic fungus, Aspergillus sp. We examined the effects of toluhydroquinone on angiogenesis using HUVECs. We identified that toluhydroquinone inhibited the activity of β-catenin and down-regulated Ras/Raf/MEK/ERK signaling which are crucial components during angiogenesis. In addition, the expression and activity of MMPs are reduced by the treatment of toluhydroquinone. In conclusion, we confirmed that toluhydroquinone has inhibitory effects on angiogenic behaviors of human endothelial cells, HUVECs. Our findings suggest that toluhydroquinone can be proposed as a potent anti-angiogenesis drug candidate to treat cancers. PMID:25776491

  17. Sun, shade, and secondary metabolites

    Science.gov (United States)

    My research program focuses on understanding plant primary and secondary metabolites. Grape secondary metabolites, such as phenolics, have long been valuable for the organoleptic properties they impart to fruit and wine, and, more recently, for their possible health benefits. These compounds develop...

  18. Secondary metabolites from Eremostachys laciniata

    DEFF Research Database (Denmark)

    Calis, Ihsan; Güvenc, Aysegül; Armagan, Metin;

    2008-01-01

    metabolites were elucidated from spectroscopic (UV, IR, 1D- and 2D-NMR) and ESI-MS evidence, as well as from their specific optical rotation. The presence of these metabolites of three different classes strongly supports the close relationship of the genera Eremostachys and Phlomis....

  19. Variability of benzene exposure among filling station attendants

    International Nuclear Information System (INIS)

    A monitoring survey of filling station attendants aimed at identifying sources of variability of exposure to benzene and other aromatics was carried out. Concurrent samples of the worker's breathing zone air, atmospheric air in the service station proximity, and gasoline were collected, along with information about daily workloads and other exposure-related factors. Benzene personal exposure was characterised by a small between-worker variability and a predominant within-worker variance component. Such elevated day-to-day variability yields to imprecise estimates of mean personal exposure. Almost 70% of the overall personal exposure variance was explained by a model including daily benzene from dispensed fuel, presence of a shelter over the refueling area, amount of fuel supplied to the station if a delivery occurred, and background atmospheric benzene concentration

  20. Electronic structure of benzene adsorbed on Ni and Cu surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Weinelt, M.; Nilsson, A.; Wassdahl, N. [Uppsala Univ. (Sweden)] [and others

    1997-04-01

    Benzene has for a long time served as a prototype adsorption system of large molecules. It adsorbs with the molecular plane parallel to the surface. The bonding of benzene to a transition metal is typically viewed to involve the {pi} system. Benzene adsorbs weakly on Cu and strongly on Ni. It is interesting to study how the adsorption strength is reflected in the electronic structure of the adsorbate-substrate complex. The authors have used X-ray Emission (XE) and X-ray Absorption (XA) spectroscopies to selectively study the electronic states localized on the adsorbed benzene molecule. Using XES the occupied states can be studies and with XAS the unoccupied states. The authors have used beamline 8.0 and the Swedish endstation equipped with a grazing incidence x-ray spectrometer and a partial yield absorption detector. The resolution in the XES and XAS were 0.5 eV and 0.05 eV, respectively.

  1. Intrinsic and enhanced biodegradation of benzene in strongly reduced aquifers

    NARCIS (Netherlands)

    Heiningen, W.N.M. van; Rijnaarts, H.H.M; Langenhoff, A.A.M.

    1999-01-01

    Laboratory microcosm studies were performed to examine intrinsic and enhanced benzene bioremediation using five different sediment and groundwater samples from three deeply anaerobic aquifers sited in northern Netherlands. The influence of addition of nitrate, sulfate, limited amounts of oxygen, and

  2. Magnetically rotational reactor for absorbing benzene emissions by ionic liquids

    Institute of Scientific and Technical Information of China (English)

    Yangyang; Jiang; Chen; Guo; Huizhou; Liu

    2007-01-01

    A magnetically rotational reactor (MRR) has been developed and used in absorbing benzene emissions. The MRR has a permanent magnet core and uses magnetic ionic liquid [bmim]FeCl4 as absorbent. Benzene emissions were carried by N2 into the MRR and were absorbed by the magnetic ionic liquid. The rotation of the permanent magnet core provided impetus for the agitation of the magnetic ionic liquid, enhancing mass transfer and making benzene better dispersed in the absorbent. 0.68 g benzene emissions could be absorbed by a gram of [bmim]FeCl4, 0.27 and 0.40 g/ghigher than that by [bmim]PF6 and [bmim]BF4, respectively. The absorption rate increased with increasing rotation rate of the permanent magnet.

  3. Comparison between the efficacy of 10% zinc sulfate solution with 4% hydroquinone cream on improvement of melasma

    Directory of Open Access Journals (Sweden)

    Fariba Iraji

    2012-01-01

    Full Text Available Background: Melasma, a common disorder of hyperpigmentation, is often difficult to treat. Although 10% zinc sulfate solution has been reported to be useful for patients with melasma, controlled trials are lacking. Materials and Methods: 72 women with moderate to severe melasma were divided randomly into 2 groups. Group A were treated with 10% zinc sulfate solution and group B with 4% hydroquinone cream twice-daily. The results were evaluated by photoevaluation by patients based on subjective satisfaction and a blinded dermatologist using MASI score. Assessments were obtained at baseline and at 2 and 6 months after starting treatment. Results: According to MASI score changes during treatment, there was a reduction in both groups at 2 months, however, the reduction in group B was more significant (the reduction in mean ± SD MASI was 0.7 ± 0.7 in group A vs. 2.7 ± 1.6 in group B. In addition, the patients in group B continued to decrease MASI score for the remainder of the study period at 6 months follow-up (0.3 ± 0.5 in comparison with patients in group A who did not show more reduction in MASI score. Conclusions: The study indicates that topical zinc sulfate is not as effective in treating disease as was observed in the previous open study. A comparative study with sunscreen and placebo is necessary to determine if topical zinc sulfate is truly superior to sunscreen and placebo in this respect.

  4. A Double-Blind, Randomized Clinical Trial of Niacinamide 4% versus Hydroquinone 4% in the Treatment of Melasma

    Directory of Open Access Journals (Sweden)

    Josefina Navarrete-Solís

    2011-01-01

    Full Text Available Background. Multiple modalities have been used in the treatment of melasma with variable success. Niacinamide has anti-inflammatory properties and is able to decrease the transfer of melanosomes. Objective. To evaluate the therapeutic effect of topical niacinamide versus hydroquinone (HQ in melasma patients. Patients and Methods. Twenty-seven melasma patients were randomized to receive for eight weeks 4% niacinamide cream on one side of the face, and 4% HQ cream on the other. Sunscreen was applied along the observation period. They were assessed by noninvasive techniques for the evaluation of skin color, as well as subjective scales and histological sections initially and after the treatment with niacinamide. Results. All patients showed pigment improvement with both treatments. Colorimetric measures did not show statistical differences between both sides. However, good to excellent improvement was observed with niacinamide in 44% of patients, compared to 55% with HQ. Niacinamide reduced importantly the mast cell infiltrate and showed improvement of solar elastosis in melasma skin. Side effects were present in 18% with niacinamide versus 29% with HQ. Conclusion. Niacinamide induces a decrease in pigmentation, inflammatory infiltrate, and solar elastosis. Niacinamide is a safe and effective therapeutic agent for this condition.

  5. A Double-Blind, Randomized Clinical Trial of Niacinamide 4% versus Hydroquinone 4% in the Treatment of Melasma.

    Science.gov (United States)

    Navarrete-Solís, Josefina; Castanedo-Cázares, Juan Pablo; Torres-Álvarez, Bertha; Oros-Ovalle, Cuauhtemoc; Fuentes-Ahumada, Cornelia; González, Francisco Javier; Martínez-Ramírez, Juan David; Moncada, Benjamin

    2011-01-01

    Background. Multiple modalities have been used in the treatment of melasma with variable success. Niacinamide has anti-inflammatory properties and is able to decrease the transfer of melanosomes. Objective. To evaluate the therapeutic effect of topical niacinamide versus hydroquinone (HQ) in melasma patients. Patients and Methods. Twenty-seven melasma patients were randomized to receive for eight weeks 4% niacinamide cream on one side of the face, and 4% HQ cream on the other. Sunscreen was applied along the observation period. They were assessed by noninvasive techniques for the evaluation of skin color, as well as subjective scales and histological sections initially and after the treatment with niacinamide. Results. All patients showed pigment improvement with both treatments. Colorimetric measures did not show statistical differences between both sides. However, good to excellent improvement was observed with niacinamide in 44% of patients, compared to 55% with HQ. Niacinamide reduced importantly the mast cell infiltrate and showed improvement of solar elastosis in melasma skin. Side effects were present in 18% with niacinamide versus 29% with HQ. Conclusion. Niacinamide induces a decrease in pigmentation, inflammatory infiltrate, and solar elastosis. Niacinamide is a safe and effective therapeutic agent for this condition. PMID:21822427

  6. Easy processing laser reduced graphene: A green and fast sensing platform for hydroquinone and catechol simultaneous determination

    International Nuclear Information System (INIS)

    Highlights: • A sensing platform for electroanalysis is constructed based on easy processing laser reduced graphene. • Our platform is highly beneficial for the construction of sensitive electrochemical sensor and biosensor. • The easy processing method probably makes it particularly attractive to produce graphene composites by premixing GO with other materials. - Abstract: A green, fast and facile approach for the preparation of graphene is proposed for constructing an electrochemical sensing platform. The fabricated platform is applied for the simultaneous determination of hydroquinone (HQ) and catechol (CC) based on laser reduced graphene (LRG) which is prepared by a consumer-grade laser pen (< $10). Scanning electron microscopy (SEM), atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS), Raman spectrum and X-ray diffraction (XRD) confirm that the synthesis of LRG could be achieved through a simple and efficient way without any chemical reducing agents and without time consuming process. The performance of LRG modified electrode shows the excellent electrocatalytic activity of LRG toward the redox reaction of HQ and CC. Under the optimized condition, the calibration curves for HQ and CC were obtained in the range of 1 to 300 μM, 2 to 300 μM, with detection limits (S/N = 3) of 0.5 μM and 0.8 μM, respectively. Therefore, our study may provide a promising sensing platform for a variety of electroanalysis applications

  7. Simultaneous determination of hydroquinone, catechol and resorcinol by voltammetry using graphene screen-printed electrodes and partial least squares calibration.

    Science.gov (United States)

    Aragó, Miriam; Ariño, Cristina; Dago, Àngela; Díaz-Cruz, José Manuel; Esteban, Miquel

    2016-11-01

    Catechol (CC), resorcinol (RC) and hydroquinone (HQ) are dihydroxybenzene isomers that usually coexist in different samples and can be determined using voltammetric techniques taking profit of their fast response, high sensitivity and selectivity, cheap instrumentation, simple and timesaving operation modes. However, a strong overlapping of CC and HQ signals is observed hindering their accurate analysis. In the present work, the combination of differential pulse voltammetry with graphene screen-printed electrodes (allowing detection limits of 2.7, 1.7 and 2.4µmolL(-1) for HQ, CC and RC respectively) and the data analysis by partial least squares calibration (giving root mean square errors of prediction, RMSEP values, of 2.6, 4.1 and 2.3 for HQ, CC and RC respectively) has been proposed as a powerful tool for the quantification of mixtures of these dihydroxybenzene isomers. The commercial availability of the screen-printed devices and the low cost and simplicity of the analysis suggest that the proposed method can be a valuable alternative to chromatographic and electrophoretic methods for the considered species. The method has been applied to the analysis of these isomers in spiked tap water. PMID:27591597

  8. Positronium quenching in liquid and solid octanol and benzene

    DEFF Research Database (Denmark)

    Shantarovich, V.P.; Mogensen, O.E.; Goldanskii, V.I.

    1970-01-01

    The lifetimes of orthopositronium in several solutions in liquid and solid octanol and benzene have been measured. The Ps-quenching constant was found to be two to thirty times higher in the solid than in the liquid phase.......The lifetimes of orthopositronium in several solutions in liquid and solid octanol and benzene have been measured. The Ps-quenching constant was found to be two to thirty times higher in the solid than in the liquid phase....

  9. Pyridine-H5PMo10V2O40 hybrid catalysts for liquid-phase hydroxylation of benzene to phenol with molecular oxygen

    Institute of Scientific and Technical Information of China (English)

    GE HanQing; LENG Yan; ZHANG FuMin; PIAO JiaRui; ZHOU ChangJiang; WANG Jun

    2009-01-01

    Pyridine(Py)-modified Keggin-type vanadium-substituted heteropoly acids (PynPMo10V2O40,n=1 to 5) were prepared by a precipitation method as organic/inorganic hybrid catalysts for direct hydroxylation of benzene to phenol in a pressured batch reactor and their structures were detected by FT-IR.Among various catalysts,Py3PMo10V2O40 exhibits the highest catalytic activity (yield of phenol,11.5%),without observing the formation of catechol,hydroquinone and benzoquinone in the reaction with 80 vol% aqueous acetic acid,molecular oxygen and ascorbic acid used as the solvent,oxidant and reducing reagent,respectively.Influences of reaction temperature,reaction time,oxygen pressure,amount of ascorbic acid and catalyst on yield of phenol were investigated to obtain the optimal reaction conditions for phenol formation.Pyridine can greatly promote the catalytic activity of the Py-free catalyst (H5PMo10V2O40),mostly because the organic π electrons in the hybrid catalyst may extend their conjugation to the inorganic framework of heteropoly acid and dramatically modify the redox properties,at the same time,pyridine adsorbed on heteropoly acids can promote the effect of "pseudo-liquid phase",thus accounting for the enhancement of phenol yield.

  10. Biological monitoring of workers exposed to benzene in the coke oven industry.

    OpenAIRE

    Drummond, L; Luck, R; Afacan, A. S.; Wilson, H K

    1988-01-01

    Workers in the coke oven industry are potentially exposed to low concentrations of benzene. There is a need to establish a well validated biological monitoring procedure for low level benzene exposure. The use of breath and blood benzene and urinary phenol has been explored in conjunction with personal monitoring data. At exposures of about 1 ppm benzene, urinary phenol is of no value as an indicator of uptake/exposure. Benzene in blood was measured by head space gas chromatography but the co...

  11. 2H NMR study of dynamics of benzene-d6 interacting with humic and fulvic acids.

    Science.gov (United States)

    Eastman, Margaret A; Brothers, Lucinda A; Nanny, Mark A

    2011-05-01

    Samples of three humic acids and one fulvic acid with 1% loading of benzene-d(6) in sealed glass tubes have been studied with solid-state deuterium quadrupole-echo nuclear magnetic resonance spectroscopy. Calculated spectra combining three motional models, two isotropic models and a third more restricted small-angle wobble (SAW) motional model, are fit to the experimental spectra. One isotropic motion (ISO(v)) is assigned to vaporous benzene-d(6) due to the small line width, short T(1), and the loss of this component by about -25 °C when the temperature is lowered. The remaining two motional components, ISO(s) and SAW, are sorbed by the humic or fulvic acid. Benzene-d(6) slowly interacts with the humic substances, progressively filling SAW sites as ISO(s) motion diminishes. Both the sorption and increase in percentage of SAW motion are for the most part complete within 200 days but continue to a lesser extent over a period of a few years. For the SAW motion there are at least two and most likely a series of T(1) values, indicating more than one adsorption environment. Enthalpies of sorption, obtained from application of the van't Hoff equation to the percentages of the different motional models derived from a series of variable temperature spectra, are comparable in magnitude to the enthalpy of vaporization of benzene. In Leonardite humic acid, ΔH and ΔS for the ISO(s) to SAW transition change from positive to negative values with age, implying a transition in the driving force from an entropic effect associated with expansion and deformation in the molecular structure of the humic substance to accommodate benzene-d(6) to an enthalpic effect of strong benzene-d(6)-humic substance interactions. In contrast, at advanced ages, Suwannee River humic and fulvic acids have small positive or near zero ΔH and positive ΔS for the ISO(s) to SAW transition. PMID:21456559

  12. Exposition by inhalation to the benzene, toluene, ethyl-benzene and xylenes (BTEX) in the air. Sources, measures and concentrations

    International Nuclear Information System (INIS)

    This document presents the main techniques today available to characterize the benzene, toluene, ethyl-benzene and xylene (BTEX) concentrations in the air for different contexts: urban and rural areas or around industrial installations but also indoor and occupational area. It provides information to guide laboratories and research departments. A synthesis gives also the main emissions sources of these compounds as reference concentrations measured in different environments. (A.L.B.)

  13. Benzene activates caspase-4 and -12 at the transcription level, without an association with apoptosis, in mouse bone marrow cells lacking the p53 gene

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Jung-Yeon; Han, Jeong-Hee; Yoon, Byung-Il [Kangwon National University, School of Veterinary Medicine, Chuncheon, Gangwon (Korea); Hirabayashi, Yoko; Kodama, Yukio; Kanno, Jun [National Institute of Health Sciences, Division of Cellular and Molecular Toxicology, Center for Biological Safety and Research, Tokyo (Japan); Choi, Yang-Kyu [Konkuk University, College of Veterinary Medicine, Seoul (Korea); Inoue, Tohru [National Institute of Health Sciences, Biological Safety and Research Center, Tokyo (Japan)

    2009-08-15

    Benzene is a well-known environmental pollutant that can induce hematotoxicity, aplastic anemia, acute myelogenous leukemia, and lymphoma. However, although benzene metabolites are known to induce oxidative stress and disrupt the cell cycle, the mechanism underlying lympho/leukemogenicity is not fully understood. Caspase-4 (alias caspase-11) and -12 are inflammatory caspases implicated in inflammation and endoplasmic reticulum stress-induced apoptosis. The objectives of this study were to investigate the altered expression of caspase-4 and -12 in mouse bone marrow after benzene exposure and to determine whether their alterations are associated with benzene-induced bone marrow toxicity, especially cellular apoptosis. In addition, we evaluated whether the p53 gene is involved in regulating the mechanism, using both wild-type (WT) mice and mice lacking the p53 gene. For this study, 8-week-old C57BL/6 mice [WT and p53 knockout (KO)] were administered a benzene solution (150 mg/kg diluted in corn oil) via oral gavage once daily, 5 days/week, for 1 or 2 weeks. Blood and bone marrow cells were collected and cell counts were measured using a Coulter counter. Total mRNA and protein extracts were prepared from the harvested bone marrow cells. Then qRT-PCR and Western blotting were performed to detect changes in the caspases at the mRNA and protein level, respectively. A DNA fragmentation assay and Annexin-V staining were carried out on the bone marrow cells to detect apoptosis. Results indicated that when compared to the control, leukocyte number and bone marrow cellularity decreased significantly in WT mice. The expression of caspase-4 and -12 mRNA increased significantly after 12 days of benzene treatment in the bone marrow cells of benzene-exposed p53KO mice. However, apoptosis detection assays indicated no evidence of apoptosis in p53KO or WT mice. In addition, no changes of other apoptosis-related caspases, such as caspase-3 and -9, were found in WT or p53KO mice at the

  14. Structure-activity relationships for the fluorescence of ochratoxin A: Insight for detection of ochratoxin A metabolites

    International Nuclear Information System (INIS)

    Ochratoxin A (OTA) is a mycotoxin produced by Aspergillus and Penicillium that is widely found as a contaminant of food products. The toxin is a renal carcinogen in male rats, the cause of mycotoxicoses in pigs and has been associated with chronic human kidney diseases. Bioactivation has been implicated in OTA-mediated toxicity, although inconsistent results have been reported, due, in part, to the difficulty in detecting OTA metabolites in vivo. Liquid chromatography (LC) coupled with fluorescence detection (FLD) is the most widely used analytical detection method for OTA. Under acidic conditions the toxin generates blue fluorescence (465 nm) that is due to an excited state intramolecular proton transfer (ESIPT) process that generates an emissive keto tautomer. Disruption of this ESIPT process quenches fluorescence intensity and causes a blue shift in emission maxima. The aim of the present study was to determine the impact of the C5-chlorine atom, the lactone moiety and the amide bond on OTA fluorescence and derive optical parameters for OTA metabolites that have been detected in vitro. Our results highlight the limitations of LC/FLD for OTA metabolites that do not undergo ESIPT. For emissive derivatives, our absorption and emission data improves the sensitivity of LC/FLD (3-4-fold increase in the limit of detection (LOD)) for OTA analogues bearing a C5-OH group, such as the hydroquinone (OTHQ) metabolite and the glutathione conjugate of OTA (OTA-GSH). This increased sensitivity may facilitate the detection of OTA metabolites bearing a C5-OH group in biological fluids and enhance our understanding of OTA-mediated toxicity

  15. Structure-activity relationships for the fluorescence of ochratoxin A: Insight for detection of ochratoxin A metabolites

    Energy Technology Data Exchange (ETDEWEB)

    Frenette, Christine; Paugh, Robert J. [Departments of Chemistry and Toxicology, University of Guelph, Guelph, Ontario, N1G 2W1 (Canada); Tozlovanu, Mariana; Juzio, Maud [ENSAT, UMR CNRS 5503, 1 Avenue Agrobiopole 31326 Auzeville-Tolosane (France); Pfohl-Leszkowicz, Annie [ENSAT, UMR CNRS 5503, 1 Avenue Agrobiopole 31326 Auzeville-Tolosane (France)], E-mail: leszkowicz@ensat.fr; Manderville, Richard A. [Departments of Chemistry and Toxicology, University of Guelph, Guelph, Ontario, N1G 2W1 (Canada)], E-mail: rmanderv@uoguelph.ca

    2008-06-09

    Ochratoxin A (OTA) is a mycotoxin produced by Aspergillus and Penicillium that is widely found as a contaminant of food products. The toxin is a renal carcinogen in male rats, the cause of mycotoxicoses in pigs and has been associated with chronic human kidney diseases. Bioactivation has been implicated in OTA-mediated toxicity, although inconsistent results have been reported, due, in part, to the difficulty in detecting OTA metabolites in vivo. Liquid chromatography (LC) coupled with fluorescence detection (FLD) is the most widely used analytical detection method for OTA. Under acidic conditions the toxin generates blue fluorescence (465 nm) that is due to an excited state intramolecular proton transfer (ESIPT) process that generates an emissive keto tautomer. Disruption of this ESIPT process quenches fluorescence intensity and causes a blue shift in emission maxima. The aim of the present study was to determine the impact of the C5-chlorine atom, the lactone moiety and the amide bond on OTA fluorescence and derive optical parameters for OTA metabolites that have been detected in vitro. Our results highlight the limitations of LC/FLD for OTA metabolites that do not undergo ESIPT. For emissive derivatives, our absorption and emission data improves the sensitivity of LC/FLD (3-4-fold increase in the limit of detection (LOD)) for OTA analogues bearing a C5-OH group, such as the hydroquinone (OTHQ) metabolite and the glutathione conjugate of OTA (OTA-GSH). This increased sensitivity may facilitate the detection of OTA metabolites bearing a C5-OH group in biological fluids and enhance our understanding of OTA-mediated toxicity.

  16. Evaluation of various strategies to formation of pH responsive hydroquinone-terminated films on carbon electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Holm, Allan Hjarbaek; Vase, Karina Hojrup [Department of Chemistry, University of Aarhus, Langelandsgade 140, DK-8000 Aarhus (Denmark); Winther-Jensen, Bjorn [Danish Polymer Centre, Department of Chemical Engineering, Technical University of Denmark, 2800 Kgs. Lyngby (Denmark); Pedersen, Steen Uttrup [Department of Chemistry, University of Aarhus, Langelandsgade 140, DK-8000 Aarhus (Denmark)], E-mail: sup@chem.au.dk; Daasbjerg, Kim [Department of Chemistry, University of Aarhus, Langelandsgade 140, DK-8000 Aarhus (Denmark)], E-mail: kdaa@chem.au.dk

    2007-12-31

    The hydroquinone/quinone (H{sub 2}Q/Q) redox system was tethered to glassy carbon surfaces using first an electrochemical pre-oxidation treatment to afford carboxylic acid functionalities followed by immobilizing the H{sub 2}Q precursor, n-(2,5-dimethoxyphenyl)alkan-1-amine (general structure: H{sub 2}N-(CH{sub 2}){sub n}-C{sub 6}H{sub 3}(OCH{sub 3}){sub 2}, n = 1, 2, 4, 8, and 12), by carbodiimide chemistry and a final demethylation reaction. The resultant surfaces exhibited the expected chemical reversibility in aqueous solution with a pH-sensitive position of the formal potential ({approx}55 mV/pH unit), and an increase in the peak potential separation going from 0.02 V for n = 1 to 0.21 V for n = 12. The films were very robust and could withstand prolonged sonication and relatively large potential excursions. While the films followed the expected kinetic distance dependence for up to 4 methylene units the electrode kinetics was faster than expected for longer alkyl spacers. We suggest that film disorder, electrode-mediating effects, and a roughened electrode material could account for these apparent inconsistencies. To further understand such effects, two complementary electrode modification strategies leading to better film ordering on carbon were adapted; immobilizing a thin layer of benzoic acid by oxidative deposition of 4-aminobenzoic acid or employing a plasma deposition process to tether an acid analogue. Analysis of the various electrodes was accomplished by electrochemical methods, atomic force microscopy, and X-ray photoelectron spectroscopy.

  17. In vivo hydroquinone exposure alters circulating neutrophil activities and impairs LPS-induced lung inflammation in mice.

    Science.gov (United States)

    Ribeiro, André Luiz Teroso; Shimada, Ana Lúcia Borges; Hebeda, Cristina Bichels; de Oliveira, Tiago Franco; de Melo Loureiro, Ana Paula; Filho, Walter Dos Reis Pereira; Santos, Alcinéa Meigikos Dos Anjos; de Lima, Wothan Tavares; Farsky, Sandra Helena Poliselli

    2011-10-01

    Hydroquinone (HQ) is an environmental contaminant which causes immune toxicity. In this study, the effects of exposure to low doses of HQ on neutrophil mobilization into the LPS-inflamed lung were investigated. Male Swiss mice were exposed to aerosolized vehicle (control) or 12.5, 25 or 50ppm HQ (1h/day for 5 days). One hour later, oxidative burst, cell cycle, DNA fragmentation and adhesion molecules expressions in circulating neutrophils were determined by flow cytometry, and plasma malondialdehyde (MDA) levels were measured by HPLC. Also, 1h later the last exposures, inflammation was induced by LPS inhalation (0.1mg/ml/10min) and 3h later, the numbers of leukocytes in peripheral blood and in the bronchoalveolar lavage fluid (BALF) were determined using a Neubauer chamber and stained smears; adhesion molecules expressed on lung microvessel endothelial cells were quantified by immunohistochemistry; myeloperoxidase (MPO) activity was measured in the lung tissue by colorimetric assay; and cytokines in the BALF were determined by ELISA. In vivo HQ exposure augmented plasma MDA levels and oxidative activity of neutrophils, but did not cause alterations in cell cycle and DNA fragmentation. Under these conditions, the number of circulating leukocytes was not altered, but HQ exposure reduced LPS-induced neutrophil migration into the alveolar space, as these cells remained in the lung tissue. The impaired neutrophil migration into BALF may not be dependent on reduced cytokines secretions in the BALF and lung endothelial adhesion molecules expressions. However, HQ exposure increased the expression of β(2) and β(3) integrins and platelet-endothelial cell adhesion molecule-1 (PECAM-1) in neutrophils, which were not further enhanced by fMLP in vitro stimulation, indicating that HQ exposure activates circulating neutrophils, impairing further stimulatory responses. Therefore, it has been shown, for the first time, that neutrophils are target of lower levels of in vivo HQ

  18. Halogen-substituted (C-β-D-glucopyranosyl)-hydroquinone regioisomers: synthesis, enzymatic evaluation and their binding to glycogen phosphorylase.

    Science.gov (United States)

    Alexacou, Kyra-Melinda; Zhang, Yun Zhi; Praly, Jean-Pierre; Zographos, Spyros E; Chrysina, Evangelia D; Oikonomakos, Nikos G; Leonidas, Demetres D

    2011-09-01

    Electrophilic halogenation of C-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl) 1,4-dimethoxybenzene (1) afforded regioselectively products halogenated at the para position to the D-glucosyl moiety (8, 9) that were deacetylated to 3 (chloride) and 16 (bromide). For preparing meta regioisomers, 1 was efficiently oxidized with CAN to afford C-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl) 1,4-benzoquinone 2 which, in either MeOH or H(2)O-THF containing few equivalents of AcCl, added hydrochloric acid to produce predominantly meta (with respect to the sugar moiety) chlorinated hydroquinone derivatives 5 and 18, this latter being deacetylated to 4. The deacetylated meta (4, 5) or para (3, 16) halohydroquinones were evaluated as inhibitors of glycogen phosphorylase (GP, a molecular target for inhibition of hepatic glycogenolysis under high glucose concentrations) by kinetics and X-ray crystallography. These compounds are competitive inhibitors of GPb with respect to α-D-glucose-1-phosphate. The measured IC(50) values (μM) [169.9±10.0 (3), 95 (4), 39.8±0.3 (5) 136.4±4.9 (16)] showed that the meta halogenated inhibitors (4, 5) are more potent than their para analogs (3, 16). The crystal structures of GPb in complex with these compounds at high resolution (1.97-2.05 Å) revealed that the inhibitors are accommodated at the catalytic site and stabilize the T conformation of the enzyme. The differences in their inhibitory potency can be interpreted in terms of variations in the interactions with protein residues of the different substituents on the aromatic part of the inhibitors. PMID:21821421

  19. Lymphocyte chromosome breakage in low benzene exposure among Indonesian workers

    Directory of Open Access Journals (Sweden)

    Dewi S. Soemarko

    2015-01-01

    Full Text Available Background: Benzene has been used in industry since long time and its level in environment should be controled. Although environmental benzene level has been controlled to less than 1 ppm, negative effect of benzene exposure is still observed, such as chromosome breakage. This study aimed to know the prevalence of lymphocyte chromosome breakage and the influencing factors among workers in low level benzene exposure.Methods: This was a cross sectional study in oil & gas industry T, conducted between September 2007 and April 2010. The study subjects consisted of 115 workers from production section and head office. Data on type of work, duration of benzene exposure, and antioxidant consumption were collected by interview as well as observation of working process. Lymphocyte chromosome breakage was examined by banding method. Analysis of relationship between chromosome breakage and risk factors was performed by chi-square and odd ratio, whereas the role of determinant risk factors was analyzed by multivariate forward stepwise.Results: Overall lymphocyte chromosome breakage was experieced by 72 out of 115 subjects (62.61%. The prevalence among workers at production section was 68.9%, while among administration workers was 40% (p > 0.05. Low antioxidant intake increases the risk of chromosome breakage (p = 0.035; ORadjusted = 2.90; 95%CI 1.08-7.78. Other influencing factors are: type of work (p = 0,10; ORcrude = 3.32; 95% CI 1.33-8.3 and chronic benzene exposure at workplace (p = 0.014; ORcrude = 2.61; 95% CI 1.2-5.67, while the work practice-behavior decreases the lymphocyte chromosome breakage (p = 0.007; ORadjusted = 0.30; 95% CI 0.15-0.76.Conclusion: The prevalence of lymphocyte chromosome breakage in the environment with low benzene exposure is quite high especially in production workers. Chronic benzene exposure in the workplace, type of work, and low antioxidant consumption is related to lymphocyte chromosome breakage. Thus, benzene in the

  20. Canada-wide standard for benzene phase 2

    International Nuclear Information System (INIS)

    On the basis of available data, benzene is classified as carcinogenic to humans, and it led to the establishment, pursuant to the 1998 Canada-wide Accord on Environmental Harmonization of the Canadian Council of Ministers of the Environment (CCME) and its Canada-wide Environmental Standards Sub-Agreement, of the Canada-Wide Standard (CWS) for benzene. It is generally considered that any level of exposure carries some probability of harmful effects. A balancing act between achieving the best health and environmental protection possible and feasibility and costs associated with the reduction of emissions contributing to elevated levels of benzene in the air was performed for the development of this CWS. In June 2000, the Ministers of the Environment agreed to a phased approach to benzene reduction. To this effect, the Canada-Wide Standard for Benzene Phase 1 was ratified. By the end of 2000, a 30 per cent reduction in total benzene emissions form 1995 emission inventory levels was expected, according to Phase 1. The measures initiated during Phase 1 will continue beyond the time frame, and Phase 2 calls for a follow-through on those measures. Best management practices and jurisdictional regulations that will minimize emissions are recognized as part of Phase 2. Joint action in conjunction with other air issue programs should lead to additional reductions. Specifically, Phase 2 calls for an additional reduction of 6 kilotonnes in benzene emissions for existing facilities by the end of 2010. The minimization of benzene emissions through the application of best available pollution prevention and control techniques is contained for new and expanding facilities. The implementation of the CWS comprises the follow-up of existing initiatives resulting from the application of Phase 1 and the promotion and application of best management practices for new and expanding facilities, the determination and tracking of ancillary emission reductions of benzene realized as a result of

  1. Secondary metabolites from marine microorganisms

    Directory of Open Access Journals (Sweden)

    KELECOM ALPHONSE

    2002-01-01

    Full Text Available After 40 years of intensive research, chemistry of marine natural products has become a mature field. Since 1995, there are signals of decreased interest in the search of new metabolites from traditional sources such as macroalgae and octocorals, and the number of annual reports on marine sponges stabilized. On the contrary, metabolites from microorganisms is a rapidly growing field, due, at least in part, to the suspicion that a number of metabolites obtained from algae and invertebrates may be produced by associated microorganisms. Studies are concerned with bacteria and fungi, isolated from seawater, sediments, algae, fish and mainly from marine invertebrates such as sponges, mollusks, tunicates, coelenterates and crustaceans. Although it is still to early to define tendencies, it may be stated that the metabolites from microorganisms are in most cases quite different from those produced by the invertebrate hosts. Nitrogenated metabolites predominate over acetate derivatives, and terpenes are uncommon. Among the latter, sesquiterpenes, diterpenes and carotenes have been isolated; among nitrogenated metabolites, amides, cyclic peptides and indole alkaloids predominate.

  2. Products of the Benzene + O(3P) Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Taatjes, Craig A.; Osborn, David L.; Selby, Talitha M.; Meloni, Giovanni; Trevitt, Adam J.; Epifanovsky, Evgeny; Krylov, Anna I.; Sirjean, Baptiste; Dames, Enoch; Wang, Hai

    2009-12-21

    The gas-phase reaction of benzene with O(3P) is of considerable interest for modeling of aromatic oxidation, and also because there exist fundamental questions concerning the prominence of intersystem crossing in the reaction. While its overall rate constant has been studied extensively, there are still significant uncertainties in the product distribution. The reaction proceeds mainly through the addition of the O atom to benzene, forming an initial triplet diradical adduct, which can either dissociate to form the phenoxy radical and H atom, or undergo intersystem crossing onto a singlet surface, followed by a multiplicity of internal isomerizations, leading to several possible reaction products. In this work, we examined the product branching ratios of the reaction between benzene and O(3P) over the temperature range of 300 to 1000 K and pressure range of 1 to 10 Torr. The reactions were initiated by pulsed-laser photolysis of NO2 in the presence of benzene and helium buffer in a slow-flow reactor, and reaction products were identified by using the multiplexed chemical kinetics photoionization mass spectrometer operating at the Advanced Light Source (ALS) of Lawrence Berkeley National Laboratory. Phenol and phenoxy radical were detected and quantified. Cyclopentadiene and cyclopentadienyl radical were directly identified for the first time. Finally, ab initio calculations and master equation/RRKM modeling were used to reproduce the experimental branching ratios, yielding pressure-dependent rate expressions for the reaction channels, including phenoxy + H, phenol, cyclopentadiene + CO, which are proposed for kinetic modeling of benzene oxidation.

  3. Aggregation of deuterodichlormethane molecules with benzene molecules. Quantum-chemical calculations and spectroscopic studies

    International Nuclear Information System (INIS)

    C-D vibration band of deuterodichlormethane CD2Cl2 at its low concentration in benzene is slitted into components with frequency 2198 and 2193 cm-1 that is related to formation of weak benzene+deuterodichlormethane complexes. Quantum-chemical calculations confirm a formation of deuterodichlormethane+benzene dimer with participation of benzene's π -electron. Steric factors lead to a difference in orientation of one of deuterium atoms from the central orientation with respect to benzene ring. According to calculations the energy of deuterodichlormethane+benzene dimer is 1.2 kcal/mole. (author)

  4. Decomposition of benzene in a corona discharge at atmospheric pressure

    Energy Technology Data Exchange (ETDEWEB)

    Satoh, Kohki [Department of Electrical and Electronic Engineering, Muroran Institute of Technology, 27-1 Mizumoto, Muroran 050-8585 (Japan); Centre of Environmental Science and Disaster Mitigation for Advanced Research, Muroran Institute of Technology, 27-1 Mizumoto, Muroran 050-8585 (Japan); Matsuzawa, Toshiharu; Itoh, Hidenori [Department of Electrical and Electronic Engineering, Muroran Institute of Technology, 27-1 Mizumoto, Muroran 050-8585 (Japan)

    2008-05-01

    We investigated the decomposition characteristics of benzene in a positive DC corona discharge between multineedle and plane electrodes with a background gas of nitrogen-oxygen mixture at atmospheric pressure. We obtained C{sub 2}H{sub 2}, HCN, HCOOH, CO and CO{sub 2} as benzene fragments and by-products, and C{sub 2}H{sub 2} and HCN as minor intermediate products. Benzene was primarily converted into CO{sub 2} via CO at low oxygen concentrations (0.2%) and via CO and HCOOH at the atmospheric oxygen concentration (20%). Further, 57% and 24% of carbon atoms were deposited on the plane electrode and the discharge chamber at oxygen concentrations of 0.2% and 20%, respectively.

  5. Elevated Atmospheric Levels of Benzene and Benzene-Related Compounds from Unconventional Shale Extraction and Processing: Human Health Concern for Residential Communities

    Science.gov (United States)

    Rich, Alisa L.; Orimoloye, Helen T.

    2016-01-01

    BACKGROUND The advancement of natural gas (NG) extraction across the United States (U.S.) raises concern for potential exposure to hazardous air pollutants (HAPs). Benzene, a HAP and a primary chemical of concern due to its classification as a known human carcinogen, is present in petroleum-rich geologic formations and is formed during the combustion of bypass NG. It is a component in solvents, paraffin breakers, and fuels used in NG extraction and processing (E&P). OBJECTIVES The objectives of this study are to confirm the presence of benzene and benzene-related compounds (benzene[s]) in residential areas, where unconventional shale E&P is occurring, and to determine if benzene[s] exists in elevated atmospheric concentrations when compared to national background levels. METHODS Ambient air sampling was conducted in six counties in the Dallas/Fort Worth Metroplex with passive samples collected in evacuated 6-L Summa canisters. Samples were analyzed by gas chromatography/mass spectrometry, with sampling performed at variable distances from the facility fence line. RESULTS Elevated concentrations of benzene[s] in the atmosphere were identified when compared to U.S. Environmental Protection Agency’s Urban Air Toxics Monitoring Program. The 24-hour benzene concentrations ranged from 0.6 parts per billion by volume (ppbv) to 592 ppbv, with 1-hour concentrations from 2.94 ppbv to 2,900.20 ppbv. CONCLUSION Benzene is a known human carcinogen capable of multisystem health effects. Exposure to benzene is correlated with bone marrow and blood-forming organ damage and immune system depression. Sensitive populations (children, pregnant women, elderly, immunocompromised) and occupational workers are at increased risk for adverse health effects from elevated atmospheric levels of benzene[s] in residential areas with unconventional shale E&P. PMID:27199565

  6. Benzene/nitrous oxide flammability in the precipitate hydrolysis process

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, R A [Du Pont de Nemours (E.I.) and Co., Aiken, SC (USA). Savannah River Lab.

    1989-09-18

    The HAN (hydroxylamine nitrate) process for destruction of nitrite in precipitate hydrolysis produces nitrous oxide (N2O) gas as one of the products. N2O can form flammable mixtures with benzene which is also present due to radiolysis and hydrolysis of tetraphenylborate. Extensive flame modeling and explosion testing was undertaken to define the minimum oxidant for combustion of N2O/benzene using both nitrogen and carbon dioxide as diluents. The attached memorandum interprets and documents the results of the studies.

  7. Oxidation of benzene by radiolytically produced OH radicals

    International Nuclear Information System (INIS)

    The radiolysis of N2O saturated-aqueous solutions of benzene-14C has been examined using radio-liquid chromatographic methods to follow the quantitative aspects of the reactions of hydroxycyclohexadienyl radicals. In the absence of a radical oxidant, at least five important products are produced. The total yield of 5.8 observed for the incorporation of benzene into products accounts for essentially all of the radicals initially produced from the water. Dimeric products predominate with a total yield of 4.1. Phenol is produced with a yield of only 0.8 indicating a disproportionation/ combination ratio for hydroxycyclohexadienyl radicals of 2O saturated aqueous solutions. (author)

  8. Electronic Conductivity of Polypyrrole−Dodecyl Benzene Sulfonate Complexes

    DEFF Research Database (Denmark)

    West, Keld; Bay, Lasse; Nielsen, Martin Meedom;

    2004-01-01

    The electronic conductivity of the electroactive polymer polypyrrole-dodecyl benzene sulfonate (PPy-DBS) has been characterized as function of the redox level. The polymer was synthesized with different isomers of the dopant anions: the common mixed DBS tenside and three well-defined synthetic...... dodecyl isomers (with the benzene group at positions 1, 2 and 6). The conductivity was measured both by van der Pauw measurements on PPy-DBS in the oxidized, dry state as function of temperature, and by electrochemical impedance spectroscopy as function of potential in 0.1 M NaCl aqueous electrolyte...

  9. Analysis of naltrexone urinary metabolites.

    Science.gov (United States)

    Ventura, R; de la Torre, R; Segura, J

    1988-01-01

    A reversed-phase HPLC method using ion-pair formation has been developed for the simultaneous determination of naltrexone and three urinary metabolites. The extraction of the free and conjugated metabolites was studied by liquid-solid procedures using styrene-divinylbenzene copolymers (Amberlite XAD-2) and bonded octadecyl silica supports (ODS-silica). Optimum recovery was obtained with ODS-silica extraction using 25% acetonitrile in a 5 mM diammonium phosphate buffer pH 2.1 as elution solvent. The chromatographic behaviour of naltrexone metabolites and naloxone (internal standard) was examined by varying the mobile phase composition. Increments of both the diammonium phosphate buffer concentration and the percentage of organic solvent in the eluent decreases the retention of compounds in a non-linear manner. Increments of the dodecyl sulphate (counter-ion) concentration, increases the retention time. The method was applied to determine the urinary levels of major naltrexone metabolites in a volunteer receiving a 50 mg oral dose. This is the first method reported which permits the simultaneous quantitative determination of naltrexone and its metabolites, 6beta-naltrexol, naltrexone glucuronide and 6beta-naltrexol glucuronide, in urine. PMID:16867358

  10. The past suppression of industry knowledge of the toxicity of benzene to humans and potential bias in future benzene research.

    Science.gov (United States)

    Infante, Peter F

    2006-01-01

    Petrochemical industry representatives often withhold information and misinterpret positive evidence of toxicity of benzene, even from their own research, also discouraging or delaying disclosure of findings of adverse effects to the public. They now appear to be attempting to influence study results in industry's favor by offering predetermined conclusions about study results as part of an effort to draw financial support for the studies. The American Petroleum Institute is currently raising funds for benzene research being conducted in China for which it has already announced the intended conclusions. PMID:16967835

  11. Hydroxylation and Carboxylation—Two Crucial Steps of Anaerobic Benzene Degradation by Dechloromonas Strain RCB

    OpenAIRE

    Chakraborty, Romy; Coates, John D.

    2005-01-01

    Benzene is a highly toxic industrial compound that is essential to the production of various chemicals, drugs, and fuel oils. Due to its toxicity and carcinogenicity, much recent attention has been focused on benzene biodegradation, especially in the absence of molecular oxygen. However, the mechanism by which anaerobic benzene biodegradation occurs is still unclear. This is because until the recent isolation of Dechloromonas strains JJ and RCB no organism that anaerobically degraded benzene ...

  12. Are there Efimov trimers in hexafluorobenzene rather than in benzene vapor itself?

    International Nuclear Information System (INIS)

    Is there a spectroscopic method to detect an Efimov state? Following our proposal of an Efimov state arising from three pseudo bosons (generalized Cooper pairs) in benzene, our spectroscopic studies have found no evidence of Efimov trimers (ET) in h6- or d6-benzene. However, hexafluoro-benzene has shown peaks that we attributed to ET and the pseudo bosons. The experimental evidence suggests that benzene pseudo bosons and subsequently ET are quite sensitive to the surroundings

  13. Electrochemical study of benzene on Pt of various surface structures in alkaline and acidic solutions

    OpenAIRE

    Montilla Jiménez, Francisco; Morallón Núñez, Emilia; Vázquez Picó, José Luis

    2002-01-01

    The electrochemical behaviour of benzene on platinum electrodes (polycrystalline and single-crystal electrodes) has been studied in acidic and alkaline solutions. In acid solutions the reduction of benzene to cyclohexane takes place in all the platinum surface structure employed, however it does not occur in alkaline media (0.1 M NaOH). In this case, the hydrogen adsorption/desorption processes displace the adsorbed benzene from the electrode surface. The oxidation of benzene is also af...

  14. Study on serum metabonomics of rats exposed to low-dose ionizing radiation, carbon monoxide, benzene and noise

    Directory of Open Access Journals (Sweden)

    Qing-rong WANG

    2015-07-01

    Full Text Available Objective To investigate the combined effects of low-dose ionizing radiation, carbon monoxide, benzene and noise on serum metabolites and the mechanism of injury induced by these complex environmental factors in rats. Methods  Sixteen adult SD rats were randomly divided into control group and exposed group (8 each. The exposed group received the combined effect every day for 7 days. At the end of experiment, sera were collected from the abdominal aorta of rats. The metabolic fingerprint of serum was obtained by 1H nuclear magnetic resonance (1H NMR spectroscopy and determined with pattern recognition techniques of principal component analysis (PCA and orthogonal signal correction-partial least squares (OSC-PLS. The similarities and differences in metabolic profiles between two groups were visualized by SIMCA-P software. Results The rat serum 1H NMR spectra revealed different metabolic spectra between the control group and exposed group. The OSC-PLS plots of the serum samples presented respectively marked clustering between the two groups. Compared with the control group, the contents of lipid, high density lipoprotein, glycine/glucose, N-acetyl glycoprotein 1, N-acetyl glycoprotein 2, phosphatidyl choline and unsaturated fatty acid increased, while those of lactic acid, threonine/lipid, alanine, creatine, glycerylphosphorylcholine/ trimethylamine oxide, low density lipoprotein/high density lipoprotein, low density lipoprotein, very low density lipoprotein/ low density lipoprotein, very low density lipoprotein and saturated fatty acid decreased. Conclusions Combination of low-dose ionizing radiation, carbon monoxide, benzene and noise could induce changes of serum metabolites in rats, involving in immune function, renal function and energy metabolism. The NMR-based-metabonomics method has potential of application in research on combined biological effects of the complex environmental factors. DOI: 10.11855/j.issn.0577-7402.2015.07.09

  15. Carcinogenic Effects of Benzene: An Update (1997 External Review Draft)

    Science.gov (United States)

    In 1992, the U.S. Environmental Protection Agency's (EPA's) Office of Mobile Sources (OMS) requested the National Center for Environmental Assessment (NCEA) to provide an updated characterization of the cancer risk of benzene to humans. The previous characterization of the carcin...

  16. Instrument for benzene and toluene emission measurements of glycol regenerators

    International Nuclear Information System (INIS)

    We introduce an in-field and in-explosive atmosphere useable instrument, which can measure the benzene and toluene concentration in two gas and two glycol samples produced by natural gas dehydration units. It is a two-phase, on-line gas chromatograph with a photoacoustic spectroscopy based detector. The time resolution is 10 min per cycle and the minimum detectable concentrations are 2 mg m−3 for benzene, 3 mg m−3 for toluene in natural gas, and 5 g m−3 for benzene and 6 g m−3 for toluene in glycol. Test measurements were carried out at a dehydration plant belonging to MOL Hungarian Oil and Gas Company. Benzene and toluene emissions of gas dehydration unit are calculated from the measured values based on mass balance of a glycol regenerator. The relationship between the outdoor temperature and the measured concentration was observed which is caused by temperature-dependent operation of the whole dehydration unit. Emission decreases with increase of outdoor temperature. (paper)

  17. Upstream petroleum industry glycol dehydrator benzene emissions status report

    International Nuclear Information System (INIS)

    The population of dehydrators referred to are located in the Western Sedimentary Basin in northeast British Columbia, Alberta and Saskatchewan, and includes units installed at wellsites, compressor stations, gas plants, central crude oil treating facilities, and reservoir or salt cavern gas storage facilities. Benzene emissions from the still column vent on glycol dehydrators occur as a result of glycol's strong affinity for aromatic hydrocarbons, including benzene. A study was carried out to: 1) develop a list of oil and gas companies operating in Canada, 2) develop an equipment and benzene emissions inventory of glycol dehydrators, 3) develop a database in Microsoft Access format to gather and maintain inventory and emission data, 4) evaluate and validate at least 10% of the reported data, 5) develop a list of companies that manufacture dehydrators and incinerators to determine how many new dehydrators were sold for use in Canada in 1998, and 6) prepare a report summarizing findings and recommendations. The companies included in the survey were the oil and gas companies identified by the Nickels' Oil and Gas Index and others provided by CAPP, CGA, and SEPAC. The project was carried out to gather glycol dehydrator equipment and still column vent benzene emissions information. 8 refs

  18. Degradation of benzene and other aromatic hydrocarbons by anaerobic bacteria

    NARCIS (Netherlands)

    Weelink, S.A.B.

    2008-01-01

    Accidental spills, industrial discharges and gasoline leakage from underground storage tanks have resulted in serious pollution of the environment with monoaromatic hydrocarbons, such as benzene, toluene, ethylbenzene and xylene (so-called BTEX). High concentrations of BTEX have been detected in soi

  19. The ototoxic effects of ethyl benzene in rats

    NARCIS (Netherlands)

    Cappaert, N.L.M.; Klis, S.F.L.; Muijser, H.; Groot, J.C.M.J. de; Kulig, B.M.; Smoorenburg, G.F.

    1999-01-01

    Exposure to organic solvents has been shown to be ototoxic in animals and there is evidence that these solvents can induce hearing loss in humans. In this study, the effects of inhalation of the possibly ototoxic solvent ethyl benzene on the cochlear function and morphology were evaluated using thre

  20. Extraction of cadmium thiocyanate complex by tributyl phosphate in benzene

    Energy Technology Data Exchange (ETDEWEB)

    Singh, D.; Tandon, S.N. (Roorkee Univ. (India). Dept. of Chemistry)

    1981-09-01

    The extraction of cadmium thiocyanate complex has been studied in benzene solution of tri-n-butyl phosphate. The species extracted is shown to be Cd(SCN)X.4TBP, where X is a common anion. The extraction data have also been used for achieving some metal ion separation.

  1. Selective Oxidation of Benzene to Phenol. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Sherif, F.; Kung, H.; Marshall, C.

    2000-09-30

    Direct catalytic oxidation of commodity aromatics to phenolic compounds was studied by a team from Akzo Nobel Chemicals, Argonne National Lab., and Northwestern University. Results did not exceed previously published performance. The object of the project was to selectively oxidize benzene to phenol using a conventional oxidant.

  2. 40 CFR 80.1295 - How are gasoline benzene credits used?

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 16 2010-07-01 2010-07-01 false How are gasoline benzene credits used... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1295 How are gasoline benzene credits used? (a) Credit use. (1) Gasoline...

  3. 40 CFR 80.1225 - Who must register with EPA under the gasoline benzene program?

    Science.gov (United States)

    2010-07-01

    ... gasoline benzene program? 80.1225 Section 80.1225 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene General Information § 80.1225 Who must register with EPA under the gasoline benzene program? (a) Refiners...

  4. 40 CFR 80.1358 - What acts are prohibited under the gasoline benzene program?

    Science.gov (United States)

    2010-07-01

    ... gasoline benzene program? 80.1358 Section 80.1358 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Violations and Penalties § 80.1358 What acts are prohibited under the gasoline benzene program? No person shall—...

  5. 40 CFR 80.1361 - What penalties apply under the gasoline benzene program?

    Science.gov (United States)

    2010-07-01

    ... gasoline benzene program? 80.1361 Section 80.1361 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Violations and Penalties § 80.1361 What penalties apply under the gasoline benzene program? (a) Any person liable for...

  6. 40 CFR 80.1290 - How are standard benzene credits generated?

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 16 2010-07-01 2010-07-01 false How are standard benzene credits... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1290 How are standard benzene credits generated? (a) The standard credit...

  7. 40 CFR 721.1325 - Benzene, 1-(1-methyl-bu-toxy)-4-nitro-.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Benzene, 1-(1-methyl-bu-toxy)-4-nitro... Substances § 721.1325 Benzene, 1-(1-methyl-bu-toxy)-4-nitro-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 1-(1-methylbutoxy)-4-nitro- (PMN...

  8. 40 CFR 721.9595 - Alkyl benzene sulfonic acids and alkyl sulfates, amine salts (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkyl benzene sulfonic acids and alkyl... Significant New Uses for Specific Chemical Substances § 721.9595 Alkyl benzene sulfonic acids and alkyl...) The chemical substances identified generically as alkyl benzene sulfonic acids and alkyl...

  9. 40 CFR 80.1354 - What are the reporting requirements for the gasoline benzene program?

    Science.gov (United States)

    2010-07-01

    ... for the gasoline benzene program? 80.1354 Section 80.1354 Protection of Environment ENVIRONMENTAL... Benzene Recordkeeping and Reporting Requirements § 80.1354 What are the reporting requirements for the gasoline benzene program? (a) Beginning with earliest applicable date specified in § 80.1347(a)(2),...

  10. 40 CFR 721.1193 - Benzene, 2-bromo-1,4-dimethoxy-.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Benzene, 2-bromo-1,4-dimethoxy-. 721... Substances § 721.1193 Benzene, 2-bromo-1,4-dimethoxy-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 2-bromo-1,4-dimethoxy- (PMN...

  11. 40 CFR 80.1275 - How are early benzene credits generated?

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 16 2010-07-01 2010-07-01 false How are early benzene credits... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Averaging, Banking and Trading (abt) Program § 80.1275 How are early benzene credits generated? (a) For each averaging period...

  12. 40 CFR 721.10096 - Benzene, 1,4-bis (methoxymethyl)-.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Benzene, 1,4-bis (methoxymethyl)-. 721... Substances § 721.10096 Benzene, 1,4-bis (methoxymethyl)-. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as benzene, 1,4-bis (methoxymethyl)- (PMN...

  13. 40 CFR 721.1580 - Disubstituted benzene ether, polymer with substituted phenol (generic).

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Disubstituted benzene ether, polymer... Significant New Uses for Specific Chemical Substances § 721.1580 Disubstituted benzene ether, polymer with... chemical substance generically identified as disubstituted benzene ether, polymer with substituted...

  14. Toxicogenomic analysis of gene expression changes in rat liver after a 28-day oral benzene exposure

    NARCIS (Netherlands)

    Heijne, W.H.M.; Jonker, D.; Stierum, R.H.; Ommen, B. van; Groten, J.P.

    2005-01-01

    Benzene is an industrial chemical, component of automobile exhaust and cigarette smoke. After hepatic bioactivation benzene induces bone marrow, blood and hepatic toxicity. Using a toxicogenomics approach this study analysed the effects of benzene at three dose levels on gene expression in the liver

  15. 40 CFR 80.1235 - What gasoline is subject to the benzene requirements of this subpart?

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 16 2010-07-01 2010-07-01 false What gasoline is subject to the... PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Benzene Gasoline Benzene Requirements § 80.1235 What gasoline is subject to the benzene requirements...

  16. The Dose–Response Decrease in Heart Rate Variability: Any Association with the Metabolites of Polycyclic Aromatic Hydrocarbons in Coke Oven Workers?

    OpenAIRE

    Xiaohai Li; Yingying Feng; Huaxin Deng; Wangzhen Zhang; Dan Kuang; Qifei Deng; Xiayun Dai; Dafeng Lin; Suli Huang; Lili Xin; Yunfeng He; Kun Huang; Meian He; Huan Guo; Xiaomin Zhang

    2012-01-01

    BACKGROUND: Air pollution has been associated with an increased risk of cardiopulmonary mortality and decreased heart rate variability (HRV). However, it is unclear whether coke oven emissions (COEs) and polycyclic aromatic hydrocarbons (PAHs) are associated with HRV. OBJECTIVES: Our goal in the present study was to investigate the association of exposure to COEs and the urinary metabolite profiles of PAHs with HRV of coke oven workers. METHODS: We measured benzene soluble matter, carbon mono...

  17. A comprehensive study of benzene concentrations and emissions in Houston

    Science.gov (United States)

    Müller, Markus; Eichler, Philipp; Berk Knighton, W.; Estes, Mark; Crawford, James H.; Mikoviny, Tomas; Wisthaler, Armin

    2014-05-01

    The Houston Metropolitan Area (Greater Houston) has a population of over 6 million people, it ranks among the three fastest growing metropolises in the developed world and population growth scenarios predict it to reach megacity status in the coming two to four decades. Greater Houston is home to the largest petrochemical-manufacturing complex in the world with important consequences for the environment in the region. Direct and fugitive emissions of hydrocarbons adversely affect Houston's air quality which has been subject to intense studies over the past two decades. In 2013, NASA conducted the DISCOVER-AQ field campaign in support of developing a satellite-based capability to assess Houston's air quality in the future. Amongst other measurements, airborne, mobile ground-based and stationary ground-based measurements of benzene were carried out. Benzene is a carcinogenic air toxic with strict exposure regulations in the U.S. and in Europe. We have used the obtained comprehensive dataset to map benzene concentrations in the Houston metropolitan area, locate and identify point sources, compare industrial and traffic emissions and put them in relation to previous measurements and emission inventories. The obtained data will allow a better assessment of health risks associated with benzene exposure in a large metropolitan area that includes both traffic and industrial benzene sources. This work was funded by BMVIT / FFG-ALR in the frame of the Austrian Space Application Programme (ASAP 8, project 833451). PE was funded through the PIMMS ITN (EU-FP7, agreement number 287382). Additional resources were provided through NASA's Earth Venture program (EV-1) and the NASA Postdoctoral Program (NPP). We want to thank Scott Herndon and Aerodyne Research for their support.

  18. Evaluation of benzene exposure in petrol pump attendants and in mechanics by urinary trans, trans-muconic acid (t, t-MA determination

    Directory of Open Access Journals (Sweden)

    Teresa Cirillo

    2004-12-01

    Full Text Available

    Occupational exposure to benzene in petrol pump attendants and in mechanics was studied by examining the benzene content in both the air breathed and in the urinary metabolite trans,trans-muconic acid (t,t-MA. Thirty petrol pump attendants and thirty mechanics (as exposed workers and thirty adult male office workers (as non exposed workers were involved in the study. Measures were taken at the begin and at the end of the working shifts.

     The benzene concentrations in the breathing air samples varied from 2 to 88 μg m-3, lower than the EU acceptable limit for occupational environment. The average urinary t,t-MA in the petrol pump attendants at the begin and at the end of the working shifts ranged between 133 ± 69 and 255 ± 174 μg g-1 creatinine and in the mechanics between 204 ± 139 and 300 ± 211 μg g-1 creatinine, respectively.

    In all the participants the mean levels of urinary t,t-MA at the end of the working shifts were significantly higher than those at the beginning. In the exposed workers mean levels of urinary t,t-MA were significantly higher than in those of the non-exposed workers. The influence of the smoking was demonstrated by the urinary t,t-MA levels in smoking non-exposed subjects.

  19. Natural products: Hunting microbial metabolites

    Science.gov (United States)

    Schmidt, Eric W.

    2015-05-01

    Symbiotic bacteria synthesize many specialized small molecules; however, establishing the role these chemicals play in human health and disease has been difficult. Now, the chemical structure and mechanism of the Escherichia coli product colibactin provides insight into the link between this secondary metabolite and colorectal cancer.

  20. Primary expectations of secondary metabolites

    Science.gov (United States)

    Plant secondary metabolites (e.g., phenolics) are important for human health, in addition to the organoleptic properties they impart to fresh and processed foods. Consumer expectations such as appearance, taste, or texture influence their purchasing decisions. Thorough identification of phenolic com...

  1. The secondary metabolite bioinformatics portal

    DEFF Research Database (Denmark)

    Weber, Tilmann; Kim, Hyun Uk

    2016-01-01

    . In this context, this review gives a summary of tools and databases that currently are available to mine, identify and characterize natural product biosynthesis pathways and their producers based on ‘omics data. A web portal called Secondary Metabolite Bioinformatics Portal (SMBP at http...

  2. Supplementary measurements for air monitoring under NOVANA - Benzene and PAH; Supplerende maalinger til luftovervaagning under NOVANA - benzen og PAH

    Energy Technology Data Exchange (ETDEWEB)

    Ellermann, T.; Klenoe Noejgaard, J.; Bossi, R.

    2011-10-15

    The report presents results from a project carried out for the Danish Environmental Protection Agency. The aim of the project was to carry out several measuring campaigns in order to be able to better assess the monitoring needs for PAH and benzene in relation to EU's air quality directives. The results show that the mean concentrations of benzene are almost at the same level in Denmark's four largest cities, and that the concentrations are both below the threshold value (5mug/m3) as well as below the lower assessment threshold (2mug/m3). The report presents a method for objectively estimation the benzene concentration based on measurements of CO. The method can be applied to fulfil the monitoring need for benzene in those zones where no measurements of benzene are made. Measurements of PAH, especially benzo(a)pyrene, have been made during 12 months in the period 2010-2011 in an area with many wood burning furnaces are used (the town Jyllinge). The concentrations of benzo(a)pyrene in Jyllinge is almost three times higher than in the street H.C. Andersens Boulevard in Copenhagen. The concentrations of benzo(a)pyrene in Jylllinge are 0,6 ng/m3, which corresponds to the upper assessment threshold (0,6 ng/m3) and is 40% below the measuring value (1 ng/m3). On this basis, there is a need for re-evaluating the monitoring of PAH in the sub-programme for air under NOVANA. Measurements of PM{sub 10} showed that the levels in the towns Jyllinge, Lille Valby/Risoe and at the H.C. Oersted Institute in Copenhagen are all at about 20-22 mug/m3. (LN)

  3. Synthesis and nucleophilic aromatic substitution of 3-fluoro-5-nitro-1-(pentafluorosulfanyl)benzene.

    Science.gov (United States)

    Ajenjo, Javier; Greenhall, Martin; Zarantonello, Camillo; Beier, Petr

    2016-01-01

    3-Fluoro-5-nitro-1-(pentafluorosulfanyl)benzene was prepared by three different ways: as a byproduct of direct fluorination of 1,2-bis(3-nitrophenyl)disulfane, by direct fluorination of 4-nitro-1-(pentafluorosulfanyl)benzene, and by fluorodenitration of 3,5-dinitro-1-(pentafluorosulfanyl)benzene. The title compound was subjected to a nucleophilic aromatic substitution of the fluorine atom with oxygen, sulfur and nitrogen nucleophiles affording novel (pentafluorosulfanyl)benzenes with 3,5-disubstitution pattern. Vicarious nucleophilic substitution of the title compound with carbon, oxygen, and nitrogen nucleophiles provided 3-fluoro-5-nitro-1-(pentafluorosulfanyl)benzenes substituted in position four. PMID:26977178

  4. The Grand Canonical Monte Carlo Simulations of Benzene and Propylene in ITQ-1 Zeolite

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Grand Canonical Monte Carlo (GCMC) simulations have been performed to study the localization and adsorption behavior of benzene and propylene, in purely siliceous MWW zeolite (ITQ-1). By analyzing the locations of benzene and propylene in ITQ-1, it can be deduced that the alkylation of benzene and propylene will mainly happen in 12-MR supercages at the external surface or close to the external surface. The adsorption isotherms of benzene and propylene at 315K and 0~3.5kPa are predicted, and the results for benzene generally coincide with the trend from the experiments of a series of aromatic compounds.

  5. Product formation from thiophene by a mixed bacterial culture. Influence of benzene as growth substrate

    DEFF Research Database (Denmark)

    Rivas, Isabelle Marie; Mosbæk, Hans; Arvin, Erik

    2003-01-01

    The influence of benzene as a growth substrate on the cometabolic conversion of thiophene was investigated in batch systems with microorganisms originating from an creosote contaminated site. Benzene was shown to stimulate the conversion of thiophene with a first-order rate, during the initial...... phase of transformation. The microorganisms were able to transform thiophene in the absence of benzene at a zero-order rate. Thiophene was converted to five oxidation products, regardless of the presence of benzene. Benzene had no influence on the distribution of these oxidation products. The main...

  6. In-situ Investigation of BBr_3/benzene Solution by Fourier Transformation Infrared Spectroscopy

    Institute of Scientific and Technical Information of China (English)

    YU Li-li; GAI Li-gang; CUI De-Hang; WANG Qi-long

    2009-01-01

    By means of the in-situ Fourier transformation infrared spectroscopy(FTIR), the properties of BBr_3/ benzene solution, which is usually used as the reactant and solution to synthesize BN by benzene-thermal method, have been investigated. The results show that there are some side reactions between BBr_3 and benzene: (1) BBr_3 as an electron-deficient molecule reacts with benzene at room temperature; (2) below 100℃, substitution of Br atom for H atom of benzene(ring-H) dominates in BBr_3/benzene solution; (3) cracking of benzene ring occurs at a temperature above 100℃; (4) decomposition of benzene molecules and formation of long-chain aliphatic compounds feature the spectra of BBr_3/benzene solution collected at above 160℃. They are unfavor for BN to form when BBr_3 is excessive in the synthesis of BN by benzene-thermal route. On the basis of the experimental results, a coordination reaction mechanism via a η~2-C_6H_6 binding mode in BBr_3/benzene solution is suggested.

  7. Identification of Epoxide-Derived Metabolite(s) of Benzbromarone.

    Science.gov (United States)

    Wang, Kai; Wang, Hui; Peng, Ying; Zheng, Jiang

    2016-04-01

    Benzbromarone (BBR) is a benzofuran derivative that has been quite useful for the treatment of gout; however, it was withdrawn from European markets in 2003 because of reported serious incidents of drug-induced liver injury. BBR-induced hepatotoxicity has been suggested to be associated with the formation of a quinone intermediate. The present study reported epoxide-derived intermediate(s) of BBR. An N-acetylcysteine (NAC) conjugate derived from epoxide metabolite(s) was detected in both microsomal incubations of BBR and urine samples of mice treated with BBR. The NAC conjugate was identified as 6-NAC BBR. Ketoconazole suppressed the bioactivation of BBR to the epoxide intermediate(s), and the CYP3A subfamily was the primary enzyme responsible for the formation of the epoxide(s). The present study provided new information on metabolic activation of BBR. PMID:26792818

  8. Experimental study of removing benzene from indoor air by needle-matrix to plate streamer discharge

    International Nuclear Information System (INIS)

    The degradation of benzene by needle-matrix to plate streamer discharge was investigated at normal temperature and pressure in indoor air. The effects of benzene initial concentration, air speed, discharge power and relative humidity (RH) on benzene removal rate were systematically studied. Meanwhile, the benzene removal efficiencies by adding MnO2/SiO2-active carbon catalyst to the system were also studied. The results showed that the benzene removal rate increased with the rise of the air speed and discharge power, decreased with the rise of the benzene initial concentration, and firstly increased and then decreased with the rise of the of RH. Under the same experimental conditions, adding MnO2 catalyst to the system did not significantly improve the removal efficiency of benzene.

  9. Assessment of benzene induced oxidative impairment in rat isolated pancreatic islets and effect on insulin secretion.

    Science.gov (United States)

    Bahadar, Haji; Maqbool, Faheem; Mostafalou, Sara; Baeeri, Maryam; Rahimifard, Mahban; Navaei-Nigjeh, Mona; Abdollahi, Mohammad

    2015-05-01

    Benzene (C6H6) is an organic compound used in petrochemicals and numerous other industries. It is abundantly released to our environment as a chemical pollutant causing widespread human exposure. This study mainly focused on benzene induced toxicity on rat pancreatic islets with respect to oxidative damage, insulin secretion and glucokinase (GK) activity. Benzene was dissolved in corn oil and administered orally at doses 200, 400 and 800mg/kg/day, for 4 weeks. In rats, benzene significantly raised the concentration of plasma insulin. Also the effect of benzene on the release of glucose-induced insulin was pronounced in isolated islets. Benzene caused oxidative DNA damage and lipid peroxidation, and also reduced the cell viability and total thiols groups, in the islets of exposed rats. In conclusion, the current study revealed that pancreatic glucose metabolism is susceptible to benzene toxicity and the resultant oxidative stress could lead to functional abnormalities in the pancreas. PMID:25935538

  10. Identification of genes specifically required for the anaerobic metabolism of benzene in Geobacter metallireducens

    DEFF Research Database (Denmark)

    Zhang, Tian; Tremblay, Pier-Luc; Chaurasia, Akhilesh Kumar;

    2014-01-01

    Although the biochemical pathways for the anaerobic degradation of many of the hydrocarbon constituents in petroleum reservoirs have been elucidated, the mechanisms for anaerobic activation of benzene, a very stable molecule, are not known. Previous studies have demonstrated that Geobacter...... metallireducens can anaerobically oxidize benzene to carbon dioxide with Fe(III) as the sole electron acceptor and that phenol is an intermediate in benzene oxidation. In an attempt to identify enzymes that might be involved in the conversion of benzene to phenol, whole-genome gene transcript abundance was...... compared in cells metabolizing benzene and cells metabolizing phenol. Eleven genes had significantly higher transcript abundance in benzene-metabolizing cells. Five of these genes had annotations suggesting that they did not encode proteins that could be involved in benzene metabolism and were not further...

  11. Benzene Uptake and Glutathione S-transferase T1 Status as Determinants of S-Phenylmercapturic Acid in Cigarette Smokers in the Multiethnic Cohort

    Science.gov (United States)

    Haiman, Christopher A.; Patel, Yesha M.; Stram, Daniel O.; Carmella, Steven G.; Chen, Menglan; Wilkens, Lynne R.; Le Marchand, Loic; Hecht, Stephen S.

    2016-01-01

    Research from the Multiethnic Cohort (MEC) demonstrated that, for the same quantity of cigarette smoking, African Americans and Native Hawaiians have a higher lung cancer risk than Whites, while Latinos and Japanese Americans are less susceptible. We collected urine samples from 2,239 cigarette smokers from five different ethnic groups in the MEC and analyzed each sample for S-phenylmercapturic acid (SPMA), a specific biomarker of benzene uptake. African Americans had significantly higher (geometric mean [SE] 3.69 [0.2], p<0.005) SPMA/ml urine than Whites (2.67 [0.13]) while Japanese Americans had significantly lower levels than Whites (1.65 [0.07], p<0.005). SPMA levels in Native Hawaiians and Latinos were not significantly different from those of Whites. We also conducted a genome-wide association study in search of genetic risk factors related to benzene exposure. The glutathione S-transferase T1 (GSTT1) deletion explained between 14.2–31.6% (p = 5.4x10-157) and the GSTM1 deletion explained between 0.2%-2.4% of the variance (p = 1.1x10-9) of SPMA levels in these populations. Ethnic differences in levels of SPMA remained strong even after controlling for the effects of these two deletions. These results demonstrate the powerful effect of GSTT1 status on SPMA levels in urine and show that uptake of benzene in African American, White, and Japanese American cigarette smokers is consistent with their lung cancer risk in the MEC. While benzene is not generally considered a cause of lung cancer, its metabolite SPMA could be a biomarker for other volatile lung carcinogens in cigarette smoke. PMID:26959369

  12. Benzene Uptake and Glutathione S-transferase T1 Status as Determinants of S-Phenylmercapturic Acid in Cigarette Smokers in the Multiethnic Cohort.

    Directory of Open Access Journals (Sweden)

    Christopher A Haiman

    Full Text Available Research from the Multiethnic Cohort (MEC demonstrated that, for the same quantity of cigarette smoking, African Americans and Native Hawaiians have a higher lung cancer risk than Whites, while Latinos and Japanese Americans are less susceptible. We collected urine samples from 2,239 cigarette smokers from five different ethnic groups in the MEC and analyzed each sample for S-phenylmercapturic acid (SPMA, a specific biomarker of benzene uptake. African Americans had significantly higher (geometric mean [SE] 3.69 [0.2], p<0.005 SPMA/ml urine than Whites (2.67 [0.13] while Japanese Americans had significantly lower levels than Whites (1.65 [0.07], p<0.005. SPMA levels in Native Hawaiians and Latinos were not significantly different from those of Whites. We also conducted a genome-wide association study in search of genetic risk factors related to benzene exposure. The glutathione S-transferase T1 (GSTT1 deletion explained between 14.2-31.6% (p = 5.4x10-157 and the GSTM1 deletion explained between 0.2%-2.4% of the variance (p = 1.1x10-9 of SPMA levels in these populations. Ethnic differences in levels of SPMA remained strong even after controlling for the effects of these two deletions. These results demonstrate the powerful effect of GSTT1 status on SPMA levels in urine and show that uptake of benzene in African American, White, and Japanese American cigarette smokers is consistent with their lung cancer risk in the MEC. While benzene is not generally considered a cause of lung cancer, its metabolite SPMA could be a biomarker for other volatile lung carcinogens in cigarette smoke.

  13. 40 CFR 80.1240 - How is a refinery's or importer's compliance with the gasoline benzene requirements of this...

    Science.gov (United States)

    2010-07-01

    ... compliance with the gasoline benzene requirements of this subpart determined? 80.1240 Section 80.1240... FUELS AND FUEL ADDITIVES Gasoline Benzene Gasoline Benzene Requirements § 80.1240 How is a refinery's or importer's compliance with the gasoline benzene requirements of this subpart determined? (a) A...

  14. 40 CFR 80.1334 - What are the requirements for early compliance with the gasoline benzene program?

    Science.gov (United States)

    2010-07-01

    ... compliance with the gasoline benzene program? 80.1334 Section 80.1334 Protection of Environment ENVIRONMENTAL... Benzene Hardship Provisions § 80.1334 What are the requirements for early compliance with the gasoline benzene program? (a)(1) A refinery may comply with the benzene requirements at § 80.1230 for its RFG...

  15. The risk of hydroquinone and sunscreen over-absorption via photodamaged skin is not greater in senescent skin as compared to young skin: nude mouse as an animal model.

    Science.gov (United States)

    Hung, Chi-Feng; Chen, Wei-Yu; Aljuffali, Ibrahim A; Shih, Hui-Chi; Fang, Jia-You

    2014-08-25

    Intrinsic aging and photoaging modify skin structure and components, which subsequently change percutaneous absorption of topically applied permeants. The purpose of this study was to systematically evaluate drug/sunscreen permeation via young and senescent skin irradiated by ultraviolet (UV) light. Both young and senescent nude mice were subjected to UVA (10 J/cm(2)) and/or UVB radiation (175 mJ/cm(2)). Physiological parameters, immunohistology, and immunoblotting were employed to examine the aged skin. Hydroquinone and sunscreen permeation was determined by in vitro Franz cell. In vivo skin absorption was documented using a hydrophilic dye, rhodamine 123 (log P=-0.4), as a permeant. UVA exposure induced cyclooxygenase (COX)-2 and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) upregulation. Epidermal tight junction (TJ) were degraded by UVA. UVB increased transepidermal water loss (TEWL) from 13 to 24 g/m(2)/h. Hyperplasia and inflammation, but not loss of TJ, were also observed in UVB-treated skin. UVA+UVB- and UVA-irradiated skin demonstrated similar changes in histology and biomarkers. UVA+UVB or UVA exposure increased hydroquinone flux five-fold. A negligible alteration of hydroquinone permeation was shown with UVB exposure. Hydroquinone exhibited a lower penetration through senescent skin than young skin. Both UVA and UVB produced enhancement of oxybenzone flux and skin uptake. However, the amount of increase was less than that of hydroquinone delivery. Photoaging did not augment skin absorption of sunscreens with higher lipophilicity, including avobenzone and ZnO. Exposure to UVA generally increased follicular entrance of these permeants, which showed two- to three-fold greater follicular uptake compared to the untreated group. Photoaging had less impact on drug/sunscreen absorption with more lipophilic permeants. Percutaneous absorption did not increase in skin subjected to both intrinsic and extrinsic aging. PMID:24858384

  16. Thermodynamics of mixtures involving some (benzene derivatives+benzonitrile)

    International Nuclear Information System (INIS)

    Interactions of binary mixtures involving some benzene derivatives (ethylbenzene, o-, m-, p-xylene, isopropylbenzene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, and methoxybenzene) with benzonitrile were investigated in continuation of our previous studies on binary systems (benzene or toluene+benzonitrile). Heat capacities by volume unit, determined with a Picker flow calorimeter at T=298.15K, and densities, measured by using Picker vibrating densimeters at the temperatures (298.15 and 308.15)K, are reported. Measurements were made over the entire range of mole fraction. From the primary measurements, the corresponding excess quantities VE and Cp,mE are obtained. The magnitude of these experimental quantities together with HE literature data is discussed in terms of the nature and type of intermolecular interactions in binary mixtures

  17. Molecular Dynamics Investigation of Benzene in Supercritical Water

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Microscopic structure and diffusion properties of benzene in ambient water (298 K, 0.1 MPa) and super critical water (673-773 K, 25-35 MPa) are investigated by molecular dynamics simulation with site-site models. It is found that at the ambient condition, the water molecules surrounding a benzene molecule form a hydrogen bond network. The hydrogen bond interaction between supercritical water molecules decreases dramatically under supercritical conditions. The diffusion coefficients of both the solute molecule and solvent molecule at supercritical conditions increase by 30-180 times than those at the ambient condition. With the temperature approaching the critical temperature, the change of diffusion coefficient with pressure becomes pronounced.

  18. Benzene leaks in sight; Benzeenlekken in het vizier

    Energy Technology Data Exchange (ETDEWEB)

    Okkerse, W.J.; Van Doorn, R.; Bison, H. [DCMR Milieudienst Rijnmond, Rotterdam (Netherlands)

    2013-02-15

    About five years ago, elevated concentrations of benzene were detected at air measuring stations of the DCMR Environmental Protection Agency in the Botlek area, the Netherlands. Extensive research of potential sources in industry followed. A wide range of advanced techniques were deployed. A smart combination of techniques has ultimately resulted in the identification and clean-up of the benzene sources. A bright future is anticipated for these techniques [Dutch] Ongeveer vijf jaar geleden werden rond het Botlekgebied verhoogde benzeenconcentraties geconstateerd op luchtmeetstations van de DCMR Milieudienst Rijnmond. Een uitgebreid onderzoek naar de potentiele bronnen in de industrie was het gevolg. Daarbij is een scala aan geavanceerde technieken ingezet. Toepassing van een slimme combinatie van technieken heeft er uiteindelijk toe geleid dat benzeenbronnen werden opgespoord en gesaneerd. Een grote toekomst wordt voorzien voor deze technieken.

  19. Catalytic transformation of methyl benzenes over zeolite catalysts

    KAUST Repository

    Al-Khattaf, S.

    2011-02-01

    Catalytic transformation of three methyl benzenes (toluene, m-xylene, and 1,2,4-trimethyl benzene) has been investigated over ZSM-5, TNU-9, mordenite and SSZ-33 catalysts in a novel riser simulator at different operating conditions. Catalytic experiments were carried out in the temperature range of 300-400 °C to understand the transformation of these alkyl benzenes over large pore (mordenite and SSZ-33) in contrast to medium-pore (ZSM-5 and TNU-9) zeolite-based catalysts. The effect of reaction conditions on the isomerization to disproportionation product ratio, distribution of trimethylbenzene (TMB) isomers, and p-xylene/o-xylene ratios are reported. The sequence of reactivity of the three alkyl benzenes depends upon the pore structure of zeolites. The zeolite structure controls primarily the diffusion of reactants and products while the acidity of these zeolites is of a secondary importance. In the case of medium pore zeolites, the order of conversion was m-xylene > 1,2,4-TMB > toluene. Over large pore zeolites the order of reactivity was 1,2,4-TMB > m-xylene > toluene for SSZ-33 catalyst, and m-xylene ∼ 1,2,4-TMB > toluene over mordenite. Significant effect of pore size between ZSM-5 and TNU-9 was observed; although TNU-9 is also 3D 10-ring channel system, its slightly larger pores compared with ZSM-5 provide sufficient reaction space to behave like large-pore zeolites in transformation of aromatic hydrocarbons. We have also carried out kinetic studies for these reactions and activation energies for all three reactants over all zeolite catalysts under study have been calculated. © 2011 Elsevier B.V.

  20. Atomic Structure of Benzene Which Accounts for Resonance Energy

    OpenAIRE

    Heyrovska, Raji

    2008-01-01

    Benzene is a hexagonal molecule of six carbon atoms, each of which is bound to six hydrogen atoms. The equality of all six CC bond lengths, despite the alternating double and single bonds, and the surplus (resonance) energy, led to the suggestion of two resonanting structures. Here, the new atomic structure shows that the bond length equality is due to three carbon atoms with double bond radii bound to three other carbon atoms with resonance bond radii (as in graphene). Consequently, there ar...

  1. Degradation of benzene and other aromatic hydrocarbons by anaerobic bacteria

    OpenAIRE

    Weelink, S.A.B.

    2008-01-01

    Accidental spills, industrial discharges and gasoline leakage from underground storage tanks have resulted in serious pollution of the environment with monoaromatic hydrocarbons, such as benzene, toluene, ethylbenzene and xylene (so-called BTEX). High concentrations of BTEX have been detected in soils, sediments and groundwater. The mobility and toxicity of the BTEX compounds are of major concern. In situ bioremediation of BTEX by using naturally occurring microorganisms or introduced microor...

  2. ADSORPTION OF WATER AND BENZENE VAPOUR IN MESOPOROUS MATERIALS

    OpenAIRE

    Paulina Taba

    2008-01-01

    Mesoporous materials have attracted the attention of many researchers due to the potential applications promised by the materials. This article discusses adsorption of water and benzene vapour in mesoporous materials (mesoporous silica: MCM-41, MCM-48 and their modification). MCM-41 and MCM-48 were synthesized hydrothermally at 100 oC using cethyltrimethylammonium chloride or dodecyltrimethylammonium bromide for MCM-41 (C16) or MCM-41 (C12) respectively and a mixture of cethyltrimethylammoniu...

  3. Pure Benzene Will Be Serous Short of Supply

    Institute of Scientific and Technical Information of China (English)

    John Zheng

    2007-01-01

    @@ Benzene is one of the important ba-sic raw materials for petrochemicals.It can be used to synthesize a seriesof important chemical products suchas synthetic rubbers, synthetic resins,synthetic fibers, pharmaceuticals,pesticides, explosives and dyestuffs.It can also be used as a solvent forcoatings and rubbers and as a blend-ing agent to increase gasoline's oc-tane number in the refining sector.

  4. LED Irradiation of a Photocatalyst for Benzene, Toluene, Ethyl Benzene,and Xylene Decomposition%LED Irradiation of a Photocatalyst for Benzene,Toluene,Ethyl Benzene,and Xylene Decomposition

    Institute of Scientific and Technical Information of China (English)

    JO Wan-Kuen; KANG Hyun-Jung

    2012-01-01

    Studies on the use of gas phase applications of light emitting diodes (LEDs) in photocatalysis are scarce although their photocatalytic decomposition kinetics of environmental pollutants are likely different from those in aqueous solutions.The present study evaluated the use of chips of visible light LEDs to irradiate nitrogen doped titania (N-TiO2) prepared by hydrolysis to decompose gaseous benzene,toluene,ethyl benzene,m-xylene,p-xylene,and o-xylene.Photocatalysts calcined at different temperatures were characterized by various analytical instruments.The degradation efficiency of benzene was close to zero for all conditions.For the other compounds,a conventional 8 W daylight lamp/N-TiO2 unit gave a higher photocatalytic degradation efficiency as compared with that of visible-LED/N-TiO2 units.However,the ratios of degradation efficiency to electric power consumption were higher for the photocatalytic units that used two types of visible-LED lamps (blue and white LEDs).The highest degradation efficiency was observed with the use of a calcination temperature of 350 ℃.The average degradation efficiencies for toluene,ethyl benzene,m-xylene,p-xylene,and o-xylene were 35%,68%,94%,and 93%,respectively.The use of blue-and white-LEDs,high light intensity,and low initial concentrations gave high photocatalytic activities for the photocatalytic units using visible-LEDs.The morphological and optical properties of the photocatalysts were correlated to explain the dependence of photocatalytic activity on calcination temperature.The results suggest that visible-LEDs are energy efficient light source for photocatalytic gas phase applications,but the activity depends on the operational conditions.

  5. 2-Phenylimidazolium hemi(benzene-1,3-dicarboxylate monohydrate

    Directory of Open Access Journals (Sweden)

    Wen-Yu Zhang

    2011-08-01

    Full Text Available The asymmetric unit of the title compound, C9H9N2+·0.5C8H4O4−·H2O, contains one 2-phenylimidazolium cation, half a benzene-1,3-dicarboxylate anion and one water molecule. In the crystal, components are connected by N—H...O and O—H...O hydrogen-bonding interactions into a three-dimensional network.

  6. Secondary Metabolites from Rubiaceae Species

    OpenAIRE

    Daiane Martins; Cecilia Veronica Nunez

    2015-01-01

    This study describes some characteristics of the Rubiaceae family pertaining to the occurrence and distribution of secondary metabolites in the main genera of this family. It reports the review of phytochemical studies addressing all species of Rubiaceae, published between 1990 and 2014. Iridoids, anthraquinones, triterpenes, indole alkaloids as well as other varying alkaloid subclasses, have shown to be the most common. These compounds have been mostly isolated from the genera Uncaria, Psych...

  7. Autism and Phthalate Metabolite Glucuronidation

    OpenAIRE

    Stein, T. Peter; Schluter, Margaret D.; Steer, Robert A.; Ming, Xue

    2013-01-01

    Exposure to environmental chemicals may precipitate autism spectrum disorders (ASD) in genetically susceptible children. Differences in the efficiency of the glucuronidation process may substantially modulate substrate concentrations and effects. To determine whether the efficiency of this pathway is compromised in children with ASD, we measured the efficiency of glucuronidation for a series of metabolites derived from the commonly used plasticizer, diethylhexyl phthalate. Spot urines were co...

  8. Epigenome targeting by probiotic metabolites

    OpenAIRE

    Licciardi Paul V; Wong Sook-San; Tang Mimi LK; Karagiannis Tom C

    2010-01-01

    Abstract Background The intestinal microbiota plays an important role in immune development and homeostasis. A disturbed microbiota during early infancy is associated with an increased risk of developing inflammatory and allergic diseases later in life. The mechanisms underlying these effects are poorly understood but are likely to involve alterations in microbial production of fermentation-derived metabolites, which have potent immune modulating properties and are required for maintenance of...

  9. Kojic acid vis-a-vis its combinations with hydroquinone and betamethasone valerate in melasma: A randomized, single blind, comparative study of efficacy and safety

    Directory of Open Access Journals (Sweden)

    Kirti S Deo

    2013-01-01

    Strict photoprotection and use of a SPF 15 sunscreen was advised during the day. Patients were evaluated every 2 weeks and a fall in MASI score was calculated at the end of the study period of 12 weeks by the same investigator. Results: The response was compared according to percentage decrease in MASI score. Efficacy was evaluated among the groups at the end of 3 months using bivariate analysis and calculated by using the paired ′t′ test. The clinical efficacy of group B was the highest followed closely by group D and group A, that of group C being the lowest. Conclusion: Kojic acid in synergy with hydroquinone is a superior depigmenting agent as compared with other combinations.

  10. Dissociative electron attachment to laser-excited benzene

    International Nuclear Information System (INIS)

    We have conducted comprehensive measurements on enhanced electron attachment to ArF and KrF laser-excited benzene in the presence of Ar and N2 buffer gases. At both these laser lines, two-photon absorption leads to excitation of benzene to energies above its ionization potential. Such excitations have been shown to lead to a population of long-lived, core-excited high-Rydberg states in addition to the ionization of the molecule. Present measurements on the dependence of negative ion yield on laser fluence, benzene pressure, and applied electric field verify that the observed negative ion formation is due to the attachment of the photoelectrons to the concomitantly produced high-Rydberg states. Using a rate equation analysis, the electron attachment rate constant for the core-excited Rydberg states was estimated to be of the order of 10-4-10-3 cm3 s-1. Laser photoionization cross sections were also estimated, and the cross section at the KrF laser line is in agreement (author)

  11. Adsorption Of Water And Benzene Vapour In Mesoporous Materials

    Directory of Open Access Journals (Sweden)

    Paulina Taba

    2008-11-01

    Full Text Available Mesoporous materials have attracted the attention of many researchers due to the potential applications promised by the materials. This article discusses adsorption of water and benzene vapour in mesoporous materials (mesoporous silica: MCM-41, MCM-48 and their modification. MCM-41 and MCM-48 were synthesized hydrothermally at 100 oC using cethyltrimethylammonium chloride or dodecyltrimethylammonium bromide for MCM-41 (C16 or MCM-41 (C12 respectively and a mixture of cethyltrimethylammonium bromide and Triton X-100 for MCM-48 as templates. Their modifications were conducted by silylation of MCM-41 (C16 and MCM-48 with trimethylchloro silane (MCM16-TMCS and MCM48-TMCS and t-butyldimethylchloro silane (MCM16-TBDMCS and MCM48-TBDMCS. Results showed that MCM-41 and MCM-48 materials had hydrophobic features which were shown in the small amount of water adsorption at low P/P0. The hydrophobicity of samples used in this study decrease in the sequence: MCM-41 (C16 > MCM-48 > MCM-41 (C12. The hydrophobicity increased when MCM-41 and MCM-48 were silylated with TMCS or TBDMCS. All unsilylated MCM materials show higher affinity to benzene at low P/P0 than the silylated samples. The results of water and benzene adsorption showed that silylated samples are promising candidates as selective adsorbents for organic compounds.

  12. Methane from benzene in argon dielectric barrier discharge

    International Nuclear Information System (INIS)

    Highlights: ► Efficient on-line conversion of benzene to methane at room temperature. ► Absence of other H-atom donor suggests new type of chemistry. ► For parent loss > 90%, methane yield was ∼40% of limit due to H-atom availability. ► Surface moisture contributed ·OH radical for trace phenolic products’ formation. ► This method may emerge as an exploitable tactic for pollutants’ usable alterations. -- Abstract: A first-time account of direct, on-line, instantaneous and efficient chemical conversion of gas phase benzene to methane in argon Dielectric Barrier Discharge (DBD) is presented. In the absence of another overt hydrogen-donating source, potency of analogous parents toward methane generation is found to follow the order: benzene > toluene > p-xylene. Simultaneous production of trace amounts of phenolic surface deposits suggest (a) prompt decomposition of the parent molecules, including a large fraction yielding atomic transients (H-atom), (b) continuous and appropriate recombination of such parts, and (c) trace moisture in parent contributing ·OH radicals and additional H-atoms, which suitably react with the unreacted fraction of the parent, and also other intermediates. Results highlight Ar DBD to be a simple and exploitable technology for transforming undesirable hazardous aromatics to usable/useful low molecular weight open-chain products following the principles of green chemistry and engineering

  13. Adsorption of trichloroethylene and benzene vapors onto hypercrosslinked polymeric resin

    International Nuclear Information System (INIS)

    In this research, the adsorption equilibria of trichloroethylene (TCE) and benzene vapors onto hypercrosslinked polymeric resin (NDA201) were investigated by the column adsorption method in the temperature range from 303 to 333 K and pressures up to 8 kPa for TCE, 12 kPa for benzene. The Toth and Dubinin-Astakov (D-A) equations were tested to correlate experimental isotherms, and the experimental data were found to fit well by them. The good fits and characteristic curves of D-A equation provided evidence that a pore-filling phenomenon was involved during the adsorption of TCE and benzene onto NDA-201. Moreover, thermodynamic properties such as the Henry's constant and the isosteric enthalpy of adsorption were calculated. The isosteric enthalpy curves varied with the surface loading for each adsorbate, indicating that the hypercrosslinked polymeric resin has an energetically heterogeneous surface. In addition, a simple mathematic model developed by Yoon and Nelson was applied to investigate the breakthrough behavior on a hypercrosslinked polymeric resin column at 303 K and the calculated breakthrough curves were in high agreement with corresponding experimental data.

  14. Benzene exposure assessed by metabolite excretion in Estonian oil shale mineworkers: influence of glutathione s-transferase polymorphisms

    DEFF Research Database (Denmark)

    Sørensen, Mette; Poole, Jason; Autrup, Herman;

    2004-01-01

    oil shale mine were compared with the excretion in workers engaged in various production assignments above ground. In addition, possible modifying effects of genetic polymorphisms in glutathione S-transferases T1 (GSTT1), M1 (GSTM1), and P1 (GSTP1) on the excretion of S-PMA and t,t-MA were......,t-MA and S-PMA excretion were significantly higher in smokers compared with nonsmokers. Subjects carrying the GSTT1 wild-type excreted higher concentrations of S-PMA than subjects carrying the null genotype, suggesting that it is a key enzyme in the glutathione conjugation that leads to S-PMA. The results...

  15. Potential of Wood-Rotting Fungi to Attack Polystyrene Sulfonate and Its Depolymerisation by Gloeophyllum trabeum via Hydroquinone-Driven Fenton Chemistry.

    Directory of Open Access Journals (Sweden)

    Martin C Krueger

    Full Text Available Synthetic polymers often pose environmental hazards due to low biodegradation rates and resulting accumulation. In this study, a selection of wood-rotting fungi representing different lignocellulose decay types was screened for oxidative biodegradation of the polymer polystyrene sulfonate (PSS. Brown-rot basidiomycetes showed PSS depolymerisation of up to 50 % reduction in number-average molecular mass (Mn within 20 days. In-depth investigations with the most efficient depolymeriser, a Gloeophyllum trabeum strain, pointed at extracellular hydroquinone-driven Fenton chemistry responsible for depolymerisation. Detection of hydroxyl radicals present in the culture supernatants showed good compliance with depolymerisation over the time course of PSS degradation. 2,5-Dimethoxy-1,4-hydroquinone (2,5-DMHQ, which was detected in supernatants of active cultures via liquid chromatography and mass spectrometry, was demonstrated to drive the Fenton processes in G. trabeum cultures. Up to 80% reduction in Mn of PSS where observed when fungal cultures were additionally supplemented with 2,5-dimethoxy benzoquinone, the oxidized from of 2,5-DMHQ. Furthermore, 2,5-DMHQ could initiate the Fenton's reagent-mediated PSS depolymerisation in cell-free systems. In contrast, white-rot fungi were unable to cause substantial depolymerising effects despite the expression of lignin-modifying exo-enzymes. Detailed investigations with laccase from Trametes versicolor revealed that only in presence of certain redox mediators limited PSS depolymerisation occurred. Our results indicate that brown-rot fungi might be suitable organisms for the biodegradation of recalcitrant synthetic polymeric pollutants.

  16. Discrimination and simultaneous determination of hydroquinone and catechol by tunable polymerization of imidazolium-based ionic liquid on multi-walled carbon nanotube surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Xun; Gao, Weiwei; Zhou, Shenghai; Shi, Hongyan; Huang, Hao; Song, Wenbo, E-mail: wbsong@jlu.edu.cn

    2013-12-17

    Graphical abstract: -- Highlights: •Tunable free radical polymerization of ionic liquid on MWCNT surfaces. •Discrimination of hydroquinone and catechol at functional electrochemical interface. •Excellent performances in simultaneous determination based on cation-π interaction. -- Abstract: Tunable polymerization of ionic liquid on the surfaces of multi-walled carbon nanotubes (MWCNTs) was achieved by a mild thermal-initiation-free radical reaction of 3-ethy-1-vinylimidazolium tetrafluoroborate in the presence of MWCNTs. Successful modification of polymeric ionic liquid (PIL) on MWCNTs surfaces (PIL-MWCNTs) was demonstrated by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and X-ray photoelectron spectroscopy. The resulting PIL-MWCNTs possessed unique features of high dispersity in aqueous solution and tunable thickness of PIL layer, due to positive imidazole groups along PIL chains and controllable ionic liquid polymerization by tuning the ratio of precursor. Based on cation-π interaction between the positive imidazole groups on PIL-MWCNTs surface and hydroquinone (HQ) or catechol (CC), excellent discrimination ability toward HQ and CC and improved simultaneous detection performance were achieved. The linear range for HQ and CC were 1.0 × 10{sup −6} to 5.0 × 10{sup −4} M and 1.0 × 10{sup −6} to 4.0 × 10{sup −4} M, respectively. The detection limit for HQ was 4.0 × 10{sup −7} M and for CC 1.7 × 10{sup −7} M (S/N = 3), correspondingly.

  17. STABILITY OF HEMOGLOBIN AND ALBUMIN ADDUCTS OF BENZENE OXIDE AND 1,4-BENZOQUINONE AFTER ADMINISTRATION OF BENZENE TO F344 RATS

    Science.gov (United States)

    The stability of cysteinyl adducts of benzene oxide (BO) and mono-S-substituted cysteinyl adducts of 1,4-benzoquinone (1,4-BQ) was investigated in both hemoglobin (Hb) and albumin (Alb) following administration of a single oral dose of 400 mg [U-14C/13C6]benzene/kg body weight ...

  18. INVESTIGATION OF BENZENE OXIDE IN BONE MARROW AND OTHER TISSUES OF F344 RATS FOLLOWING METABOLISM OF BENZENE IN VITRO AND IN VIVO

    Science.gov (United States)

    This study examines the initial activation of benzene, exploring key aspects of its metabolism by measurement of benzene oxide (BO) and BO-protein adducts in vitro and in vivo. To assess the potential influence of various factors on the production of BO, microsomes were prepare...

  19. Differences in the pathways for metabolism of benzene in rats and mice simulated by a physiological model.

    OpenAIRE

    Medinsky, M A; Sabourin, P J; Henderson, R F; Lucier, G; Birnbaum, L S

    1989-01-01

    Studies conducted by the National Toxicology Program on the chronic toxicity of benzene indicated that B6C3F1 mice were more sensitive to the carcinogenic effects of benzene than were F344 rats. A physiological model was developed to describe the uptake and metabolism of benzene in rats and mice. Our objective was to determine if differences in toxic effects could be explained by differences in pathways for benzene metabolism or by differences in total uptake of benzene. Compartments incorpor...

  20. Decreased levels of CXC-chemokines in serum of benzene-exposed workers identified by array-based proteomics

    OpenAIRE

    Vermeulen, Roel; Lan, Qing; Zhang, Luoping; Gunn, Laura; McCarthy, Diane; Woodbury, Ronald L; McGuire, Marielena; Podust, Vladimir N.; Li, Guilan; Chatterjee, Nilanjan; Mu, Ruidong; Yin, Songnian; Rothman, Nathaniel; Smith, Martyn T.

    2005-01-01

    Benzene is an important industrial chemical and environmental contaminant that causes leukemia. To obtain mechanistic insight into benzene's mechanism of action, we examined the impact of benzene on the human serum proteome in a study of exposed healthy shoe-factory workers and unexposed controls. Two sequential studies were performed, each using sera from 10 workers exposed to benzene (overall mean benzene air level >30 ppm) and 10 controls. Serum samples were subjected to anion-exchange fra...

  1. Sorption of phenanthrene and benzene on differently structural kerogen: Important role of micropore-filling

    International Nuclear Information System (INIS)

    Shale was thermally treated to obtain a series of kerogen with varied maturation. Their chemical, structural and porous properties were related to the sorption and/or desorption behaviors of phenanthrene and benzene. As the treatment temperature increases, aliphatic and carbonyl carbon of the kerogen samples decrease, while their aromaticity and maturation increase. Meanwhile, the isothermal nonlinearity of phenanthrene and benzene increases whereas the sorption capacity and micropore adsorption volumes (Vo,d) initially increase and then decrease. The Vo,d of benzene is significantly correlated with, but higher than that of phenanthrene, suggesting similar micropore filling mechanism and molecular sieve effect. The benzene desorption exhibits hysteresis, which is related to the pore deformation of the kerogen and the entrapment of solute in the kerogen matrix. The Vo,d of phenanthrene and benzene on the kerogen samples accounts for 23–46% and 36–65% of the maximum sorption volumes, respectively, displaying the importance of the micropore filling. -- Highlights: • The microporosity estimated by benzene vapor differs greatly from that by N2. • The micropore volume changes with kerogen maturation. • The phenanthrene or benzene sorption is related to the microporosity of kerogen. • Higher adsorption volume for benzene than for phenanthrene suggests molecular sieve effect. • The pore-filling plays an important role in the sorption of phenanthrene and benzene. -- The sorption behaviors of benzene and phenanthrene are related to the microporosity of the differently matured kerogen, indicating the importance of pore-filling

  2. Current understandings and perspectives on non-cancer health effects of benzene: A global concern

    Energy Technology Data Exchange (ETDEWEB)

    Bahadar, Haji [International Campus, Tehran University of Medical Sciences (Iran, Islamic Republic of); Pharmaceutical Sciences Research Center and Faculty of Pharmacy, Tehran University of Medical Sciences (Iran, Islamic Republic of); Mostafalou, Sara [Pharmaceutical Sciences Research Center and Faculty of Pharmacy, Tehran University of Medical Sciences (Iran, Islamic Republic of); Abdollahi, Mohammad, E-mail: Mohammad.Abdollahi@UToronto.Ca [Pharmaceutical Sciences Research Center and Faculty of Pharmacy, Tehran University of Medical Sciences (Iran, Islamic Republic of)

    2014-04-15

    Objective: Benzene, as a volatile organic compound, is known as one of the main air pollutants in the environment. The aim of this review is to summarize all available evidences on non-cancerous health effects of benzene providing an overview of possible association of exposure to benzene with human chronic diseases, specially, in those regions of the world where benzene concentration is being poorly monitored. Methodology: A bibliographic search of scientific databases including PubMed, Google Scholar, and Scirus was conducted with key words of “benzene toxic health effects”, “environmental volatile organic compounds”, “diabetes mellitus and environmental pollutants”, “breast cancer and environmental pollution”, “prevalence of lung cancer”, and “diabetes prevalence”. More than 300 peer reviewed papers were examined. Experimental and epidemiologic studies reporting health effects of benzene and volatile organic compounds were included in the study. Results: Epidemiologic and experimental studies suggest that benzene exposure can lead to numerous non-cancerous health effects associated with functional aberration of vital systems in the body like reproductive, immune, nervous, endocrine, cardiovascular, and respiratory. Conclusion: Chronic diseases have become a health burden of global dimension with special emphasis in regions with poor monitoring over contents of benzene in petrochemicals. Benzene is a well known carcinogen of blood and its components, but the concern of benzene exposure is more than carcinogenicity of blood components and should be evaluated in both epidemiologic and experimental studies. Aspect of interactions and mechanism of toxicity in relation to human general health problems especially endocrine disturbances with particular reference to diabetes, breast and lung cancers should be followed up. - Highlights: • Benzene is a volatile organic compound and established blood carcinogen. • Exposure to benzene needs to be

  3. Current understandings and perspectives on non-cancer health effects of benzene: A global concern

    International Nuclear Information System (INIS)

    Objective: Benzene, as a volatile organic compound, is known as one of the main air pollutants in the environment. The aim of this review is to summarize all available evidences on non-cancerous health effects of benzene providing an overview of possible association of exposure to benzene with human chronic diseases, specially, in those regions of the world where benzene concentration is being poorly monitored. Methodology: A bibliographic search of scientific databases including PubMed, Google Scholar, and Scirus was conducted with key words of “benzene toxic health effects”, “environmental volatile organic compounds”, “diabetes mellitus and environmental pollutants”, “breast cancer and environmental pollution”, “prevalence of lung cancer”, and “diabetes prevalence”. More than 300 peer reviewed papers were examined. Experimental and epidemiologic studies reporting health effects of benzene and volatile organic compounds were included in the study. Results: Epidemiologic and experimental studies suggest that benzene exposure can lead to numerous non-cancerous health effects associated with functional aberration of vital systems in the body like reproductive, immune, nervous, endocrine, cardiovascular, and respiratory. Conclusion: Chronic diseases have become a health burden of global dimension with special emphasis in regions with poor monitoring over contents of benzene in petrochemicals. Benzene is a well known carcinogen of blood and its components, but the concern of benzene exposure is more than carcinogenicity of blood components and should be evaluated in both epidemiologic and experimental studies. Aspect of interactions and mechanism of toxicity in relation to human general health problems especially endocrine disturbances with particular reference to diabetes, breast and lung cancers should be followed up. - Highlights: • Benzene is a volatile organic compound and established blood carcinogen. • Exposure to benzene needs to be

  4. Environmental and occupational exposure to benzene by analysis of breath and blood.

    Science.gov (United States)

    Perbellini, L; Faccini, G B; Pasini, F; Cazzoli, F; Pistoia, S; Rosellini, R; Valsecchi, M; Brugnone, F

    1988-05-01

    Benzene exposure of chemical workers was studied, during the entire workshift, by continuous monitoring of workplace benzene concentration, and 16 hours after the end of the workshift by the measurement of alveolar and blood benzene concentrations and excretion of urinary phenol. Exposure of hospital staff was studied by measuring benzene concentrations in the alveolar and blood samples collected during the hospital workshift. Instantaneous environmental air samples were also collected, at the moment of the biological sampling, for all the subjects tested. A group of 34 chemical workers showed an eight hour exposure to benzene, as a geometric mean, of 1.12 micrograms/l which corresponded, 16 hours after the end of the workshift, to a geometric mean benzene concentration of 70 ng/l in the alveolar air and 597 ng/l in the blood. Another group of 27 chemical workers (group A) turned out to be exposed to an indeterminable eight hour exposure to benzene that corresponded, the morning after, to a geometric mean benzene concentration of 28 ng/l in the alveolar air and 256 ng/l in the blood. The group of hospital staff (group B) had a benzene concentration of 14 ng/l in the alveolar air and 269 ng/l in the blood. Instantaneous environmental samples showed that in the infirmaries the geometric mean benzene concentration was 58 ng/l during the examination of the 34 chemical workers, 36 ng/l during the examination of the 27 chemical workers (group A), and 5 ng/l during the examination of the 19 subjects of the hospital staff (group B). Statistical analysis showed that the alveolar and blood benzene concentrations in the 34 workers exposed to 1.12 microgram/l of benzene differed significantly from those in groups A and B. It was found, moreover, that the alveolar and blood benzene concentrations were higher in the smokers in groups A and B but not in the smokers in the group of 34 chemical workers. The slope of the linear correlation between the alveolar and the instantaneous

  5. Epigenome targeting by probiotic metabolites

    Directory of Open Access Journals (Sweden)

    Licciardi Paul V

    2010-12-01

    Full Text Available Abstract Background The intestinal microbiota plays an important role in immune development and homeostasis. A disturbed microbiota during early infancy is associated with an increased risk of developing inflammatory and allergic diseases later in life. The mechanisms underlying these effects are poorly understood but are likely to involve alterations in microbial production of fermentation-derived metabolites, which have potent immune modulating properties and are required for maintenance of healthy mucosal immune responses. Probiotics are beneficial bacteria that have the capacity to alter the composition of bacterial species in the intestine that can in turn influence the production of fermentation-derived metabolites. Principal among these metabolites are the short-chain fatty acids butyrate and acetate that have potent anti-inflammatory activities important in regulating immune function at the intestinal mucosal surface. Therefore strategies aimed at restoring the microbiota profile may be effective in the prevention or treatment of allergic and inflammatory diseases. Presentation of the hypothesis Probiotic bacteria have diverse effects including altering microbiota composition, regulating epithelial cell barrier function and modulating of immune responses. The precise molecular mechanisms mediating these probiotic effects are not well understood. Short-chain fatty acids such as butyrate are a class of histone deacetylase inhibitors important in the epigenetic control of host cell responses. It is hypothesized that the biological function of probiotics may be a result of epigenetic modifications that may explain the wide range of effects observed. Studies delineating the effects of probiotics on short-chain fatty acid production and the epigenetic actions of short-chain fatty acids will assist in understanding the association between microbiota and allergic or autoimmune disorders. Testing the hypothesis We propose that treatment with

  6. Occupational Exposure to Benzene from Painting with Epoxy and Other High Performance Coatings

    Energy Technology Data Exchange (ETDEWEB)

    JAHN, STEVEN

    2005-04-20

    Following the discovery of trace benzene in paint products, an assessment was needed to determine potential for benzene exposures to exceed the established ACGIH Threshold Limit Value (TLV) during painting operations. Sample data was collected by area industrial hygienists for benzene during routine maintenance and construction activities at Savannah River Site. A set of available data from the IH database, Sentry, was analyzed to provide guidance to the industrial hygiene staff and draw conclusions on the exposure potential during typical painting operations.

  7. Anaerobic degradation of benzene by enriched consortia with humic acids as terminal electron acceptors

    International Nuclear Information System (INIS)

    Highlights: → Enriched consortia were able to couple the anaerobic degradation of benzene to the reduction of humic acids. → Electron-equivalents derived from anaerobic benzene oxidation were highly recovered as reduced humic acids. → Several species from classes β-, δ- and γ-Proteobacteria were enriched during the anaerobic degradation of benzene. - Abstract: The anaerobic degradation of benzene coupled to the reduction of humic acids (HA) was demonstrated in two enriched consortia. Both inocula were able to oxidize benzene under strict anaerobic conditions when the humic model compound, anthraquinone-2,6-disulfonate (AQDS), was supplied as terminal electron acceptor. An enrichment culture originated from a contaminated soil was also able to oxidize benzene linked to the reduction of highly purified soil humic acids (HPSHA). In HPSHA-amended cultures, 9.3 μM of benzene were degraded, which corresponds to 279 ± 27 micro-electron equivalents (μEq) L-1, linked to the reduction of 619 ± 81 μEq L-1 of HPSHA. Neither anaerobic benzene oxidation nor reduction of HPSHA occurred in sterilized controls. Anaerobic benzene oxidation did not occur in soil incubations lacking HPSHA. Furthermore, negligible reduction of HPSHA occurred in the absence of benzene. The enrichment culture derived from this soil was dominated by two γ-Proteobacteria phylotypes. A benzene-degrading AQDS-reducing enrichment originated from a sediment sample showed the prevalence of different species from classes β-, δ- and γ-Proteobacteria. The present study provides clear quantitative demonstration of anaerobic degradation of benzene coupled to the reduction of HA.

  8. Anaerobic degradation of benzene by enriched consortia with humic acids as terminal electron acceptors

    Energy Technology Data Exchange (ETDEWEB)

    Cervantes, Francisco J., E-mail: fjcervantes@ipicyt.edu.mx [Division de Ciencias Ambientales, Instituto Potosino de Investigacion Cientifica y Tecnologica (IPICyT), Camino a la Presa San Jose 2055, Col. Lomas 4a. Seccion, San Luis Potosi, SLP, 78216 Mexico (Mexico); Mancilla, Ana Rosa; Toro, E. Emilia Rios-del [Division de Ciencias Ambientales, Instituto Potosino de Investigacion Cientifica y Tecnologica (IPICyT), Camino a la Presa San Jose 2055, Col. Lomas 4a. Seccion, San Luis Potosi, SLP, 78216 Mexico (Mexico); Alpuche-Solis, Angel G.; Montoya-Lorenzana, Lilia [Division de Biologia Molecular, Instituto Potosino de Investigacion Cientifica y Tecnologica (IPICyT), Camino a la Presa San Jose 2055, Col. Lomas 4a. Seccion, San Luis Potosi, SLP, 78216 Mexico (Mexico)

    2011-11-15

    Highlights: {yields} Enriched consortia were able to couple the anaerobic degradation of benzene to the reduction of humic acids. {yields} Electron-equivalents derived from anaerobic benzene oxidation were highly recovered as reduced humic acids. {yields} Several species from classes {beta}-, {delta}- and {gamma}-Proteobacteria were enriched during the anaerobic degradation of benzene. - Abstract: The anaerobic degradation of benzene coupled to the reduction of humic acids (HA) was demonstrated in two enriched consortia. Both inocula were able to oxidize benzene under strict anaerobic conditions when the humic model compound, anthraquinone-2,6-disulfonate (AQDS), was supplied as terminal electron acceptor. An enrichment culture originated from a contaminated soil was also able to oxidize benzene linked to the reduction of highly purified soil humic acids (HPSHA). In HPSHA-amended cultures, 9.3 {mu}M of benzene were degraded, which corresponds to 279 {+-} 27 micro-electron equivalents ({mu}Eq) L{sup -1}, linked to the reduction of 619 {+-} 81 {mu}Eq L{sup -1} of HPSHA. Neither anaerobic benzene oxidation nor reduction of HPSHA occurred in sterilized controls. Anaerobic benzene oxidation did not occur in soil incubations lacking HPSHA. Furthermore, negligible reduction of HPSHA occurred in the absence of benzene. The enrichment culture derived from this soil was dominated by two {gamma}-Proteobacteria phylotypes. A benzene-degrading AQDS-reducing enrichment originated from a sediment sample showed the prevalence of different species from classes {beta}-, {delta}- and {gamma}-Proteobacteria. The present study provides clear quantitative demonstration of anaerobic degradation of benzene coupled to the reduction of HA.

  9. Solar Powered Vapor Absorption System Using Propane And Alkylated Benzene Ab300 Oil

    OpenAIRE

    Al-Dadah, R.K.; Jackson, G.; Rezk, Ahmed

    2011-01-01

    Abstract This paper describes experimental work on a solar assisted vapour absorption air conditioning system using Propane (refrigerant) and Alkylated Benzene (AB300?refrigeration lubrication oil, absorbent). Preliminary experiments to assess the miscibility of propane in various lubricating oils namely Shell Clavus oils 32 and 64 and Alkylated Benzene oils AB150 and AB300 indicated that Propane is most miscible in Alkylated Benzene AB300. The vapour absorption system is a single ...

  10. Geographical distribution of benzene in air in northwestern Italy and personal exposure.

    OpenAIRE

    Gilli, G.; Scursatone, E; Bono, R.

    1996-01-01

    Benzene is a solvent strictly related to some industrial activities and to automotive emissions. After the reduction in lead content of fuel gasoline, and the consequent decrease in octane number, an increase in benzene and other aromatic hydrocarbons in gasoline occurred. Therefore, an increase in the concentration of these chemicals in the air as primary pollutants and as precursors of photochemical smog could occur in the future. The objectives of this study were to describe the benzene ai...

  11. ANALYSES OF CHROMOSOME ABERRATIONS IN LYMPHOCYTES AND BONE MARROW CELLS INDUCED BY RADIATION OR BENZENE

    Institute of Scientific and Technical Information of China (English)

    张鸿源; 王兰金; 等

    1995-01-01

    The chromosomoe and chromatid type aberration can be induced by benzene and the dicentric and ring ones were not observed in vitro experiment but observed in vivo one.In vitro experiment a good linear reression can be given between benzene concentrations and total aberration cells while power regression for radiation dose.The chromosome aberrations induced by benzene combined with radiation in rabbit blood lymphocytes are higher than in bone marryow cells.

  12. Benzene hemoglobin adducts in mice and rats: Characterization of formation and physiological modeling

    International Nuclear Information System (INIS)

    Benzene is a myelotoxin and a human leukemogen. Humans are exposed to this compound, both occupationally and environmentally. This study was conducted to determine whether formation of benzene-derived adducts with blood hemoglobin (Hb) can be used as a biomarker of exposure to benzene. B6C3F1 mice and F344/N rats were given 0.1 to 10,000 mumol [14C]benzene/kg body wt, orally. Twenty-four hours later, animals were euthanized, and globin was isolated from blood samples. The globin was analyzed by liquid scintillation spectrometry for the presence of [14C]benzene-derived adducts. Hb adduct formation was linear with respect to dose for amounts of up to 500 mumol [14C]benzene/kg body wt, for both rodent species. Within this linear dose-response range, mice formed adducts from [14C]benzene approximately 3.5 times less efficiently [0.022 +/- 0.010 (pmol adducts/mg globin)/(mumol/kg body wt dose)] than did rats [0.076 +/- 0.014 (pmol adducts)/(mumol/kg body wt dose)]. Benzene-derived Hb adducts also accumulated linearly when mice and rats were given up to three daily doses of 500 mumol [14C]benzene/kg body wt. These data were used to develop a physiological model for benzene-derived Hb adduct formation. Both first-order and saturable pathways for adduct formation were incorporated. The results showed that the model simulated the levels of Hb adducts in both mice and rats after oral exposures to benzene and predicted the levels of Hb adducts present after inhalation exposure. These studies suggest that Hb adducts might be useful biomarkers for human exposures to benzene

  13. Antifungal Activity of Microbial Secondary Metabolites

    OpenAIRE

    Jeffrey J Coleman; Ghosh, Suman; Okoli, Ikechukwu; Mylonakis, Eleftherios

    2011-01-01

    Secondary metabolites are well known for their ability to impede other microorganisms. Reanalysis of a screen of natural products using the Caenorhabditis elegans-Candida albicans infection model identified twelve microbial secondary metabolites capable of conferring an increase in survival to infected nematodes. In this screen, the two compound treatments conferring the highest survival rates were members of the epipolythiodioxopiperazine (ETP) family of fungal secondary metabolites, acetylg...

  14. Secondary metabolites in fungus-plant interactions

    OpenAIRE

    Pusztahelyi, Tünde; Holb, Imre J.; Pócsi, István (1961-) (biológus)

    2015-01-01

    Fungi and plants are rich sources of thousands of secondary metabolites. The genetically coded possibilities for secondary metabolite production, the stimuli of the production, and the special phytotoxins basically determine the microscopic fungi-host plant interactions and the pathogenic lifestyle of fungi. The review introduces plant secondary metabolites usually with antifungal effect as well as the importance of signaling molecules in induced systemic resistance and systemic acquired resi...

  15. Probabilistic Approach for Evaluating Metabolite Sample Integrity

    OpenAIRE

    Slaff, Barry M.; Jensen, Shane T.; Weljie, Aalim M.

    2015-01-01

    The success of metabolomics studies depends upon the "fitness" of each biological sample used for analysis: it is critical that metabolite levels reported for a biological sample represent an accurate snapshot of the studied organism's metabolite profile at time of sample collection. Numerous factors may compromise metabolite sample fitness, including chemical and biological factors which intervene during sample collection, handling, storage, and preparation for analysis. We propose a probabi...

  16. Spectroscopic study of water-NaCl-benzene mixtures at high temperatures and pressures

    OpenAIRE

    Ohya, Tomoyuki; Kitagawa, Masaaki; Jin, Yusuke; Ikawa, Shun-ichi

    2005-01-01

    Near-infrared and ultraviolet spectra of water-NaCl-benzene mixtures have been measured in the 473–573 K and 100–400 bar range and 373–498 K and 50–300 bar range, respectively. Concentrations of water in the benzene-rich phase and benzene in the water-rich phase were estimated from integrated intensities of the absorption bands. It is found that addition of NaCl in the aqueous phase suppresses transfer of water into the benzene-rich phase, and the relative decrease in water solubility in ...

  17. Human hemoglobin structural and functional alterations and heme degradation upon interaction with benzene: A spectroscopic study

    Science.gov (United States)

    Hosseinzadeh, Reza; Moosavi-Movahedi, Ali Akbar

    2016-03-01

    Here, the effect of benzene on hemoglobin structure, stability and heme prosthetic group integrity was studied by different methods. These included UV-vis absorption spectrophotometry, normal and synchronous fluorescence techniques, and differential scanning calorimetry (DSC). Our results indicated that benzene has high hemolytic potential even at low concentrations. The UV-vis spectroscopic results demonstrated that benzene altered both the globin chain and the heme prosthetic group of hemoglobin increasing met- and deoxy-Hb, while decreasing oxy-Hb. However, with increasing benzene the concentration of all species decreased due to heme destruction. The spectrophotometric results show that benzene has a high potential for penetrating the hydrophobic pocket of hemoglobin. These results were consistent with the molecular docking simulation results of benzene-hHb. Aggregation and thermal denaturation studies show that the increased benzene concentration induced hemoglobin aggregation with a decrease in stability, which is consistent with the DSC results. Conventional fluorescence spectroscopy revealed that the heme degradation species were produced in the presence of benzene. The results of constant wavelength synchronous fluorescence spectroscopy (CWSFS) indicated that at least five heme-degraded species were produced. Together, our results indicated that benzene has adverse effects on hemoglobin structure and function, and heme degradation.

  18. Determination of benzene in different food matrices by distillation and isotope dilution HS-GC/MS

    International Nuclear Information System (INIS)

    Benzene is classified by the IARC as carcinogenic to humans. Several sources may contribute for the occurrence of benzene in foods, such as, environmental contamination and the reaction of benzoate salts with ascorbic acid (naturally present or added as food additives). Matrix effect on benzene recovery (e.g. in fatty foods) and artefactual benzene formation from benzoate during analysis in the presence of ascorbate are some of the challenges presented when determining benzene in a wide range of foodstuffs. Design of experiment (DOE) was used to determine the most important variables in benzene recovery from headspace GC/MS. Based on the results of the DOE, a versatile method for the extraction of benzene from all kind of food commodities was developed. The method which consisted of distillation and isotope dilution HS-GC/MS was in-house validated. Artefactual benzene was prevented by addition of a borate buffer solution (pH 11) under distillation conditions. The method presented in this study allows the use of a matrix-independent calibration with detection limits below the legal limit established by the European Council for benzene in drinking water (1 μg L-1).

  19. Revisiting the glass transition and dynamics of supercooled benzene by calorimetric studies

    Science.gov (United States)

    Tu, Wenkang; Chen, Zeming; Li, Xiangqian; Gao, Yanqin; Liu, Riping; Wang, Li-Min

    2015-10-01

    The glass transition and dynamics of benzene are studied in binary mixtures of benzene with five glass forming liquids, which can be divided into three groups: (a) o-terphenyl and m-xylene, (b) N-butyl methacrylate, and (c) N,N-dimethylpropionamide and N,N-diethylformamide to represent the weak, moderate, and strong interactions with benzene. The enthalpies of mixing, ΔHmix, for the benzene mixtures are measured to show positive or negative signs, with which the validity of the extrapolations of the glass transition temperature Tg to the benzene-rich regions is examined. The extrapolations for the Tg data in the mixtures are found to converge around the point of 142 K, producing Tg of pure benzene. The fragility m of benzene is also evaluated by extrapolating the results of the mixtures, and a fragility m ˜ 80 is yielded. The obtained Tg and m values for benzene allow for the construction of the activation plot in the deeply supercooled region. The poor glass formability of benzene is found to result from the high melting point, which in turn leads to low viscosity in the supercooled liquid.

  20. Pressure Dependence of Molar Volume near the Melting Point in Benzene

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The pressure dependence of the molar volume was at constant temperatures close to the melting point in benzene. The molar volume of benzene was calculated using experimental data for the thermal expansivity for constant temperatures of 25℃, 28.5℃, 40℃, and 51℃ at various pressures for both the solid and liquid phases. The predictions are in good agreement with the observed volumes in both the solid and liquid phases of benzene. The predicted values of the molar volume for a constant temperature of 28.5℃ in the liquid phase of benzene agree well with experimental data in the literature.

  1. Modeling of Pervaporation Separation Benzene from Dilute Aqueous Solutions Through Polydimethylsiloxane Membranes

    Institute of Scientific and Technical Information of China (English)

    彭福兵; 姜忠义

    2005-01-01

    A modified solution-diffusion model was established based on Flory-Huggins thermodynamic theory and Fujita's free volume theory. This model was used for description of the mass transfer of removal benzene from dilute aqueous solutions through polydimethylsiloxane (PDMS) membranes. The effect of component concentration on the interaction parameter between components, that of the polymer membrane on the selectivity to benzene, and that of feed concentration and temperature on the permeation flux and separation factor of benzene/water through PDMS membranes were investigated. Calculated pervaporation fluxes of benzene and water were compared with the experimental results and were in good agreement with the experimental data.

  2. Exposure to benzene in urban workers: environmental and biological monitoring of traffic police in Rome

    OpenAIRE

    Crebelli, R; Tomei, F.; Zijno, A; Ghittori, S; M Imbriani; Gamberale, D; Martini, A.; Carere, A

    2001-01-01

    OBJECTIVES—To evaluate the contribution of traffic fumes to exposure to benzene in urban workers, an investigation on personal exposure to benzene in traffic police from the city of Rome was carried out.
METHODS—The study was performed from December 1998 to June 1999. Diffusive Radiello personal samplers were used to measure external exposures to benzene and alkyl benzenes during the workshift in 139 policemen who controlled medium to high traffic areas and in 63 office police. Moreover, as b...

  3. Diffusive Motions in Benzene and Toluene Studied with Slow Neutrons

    International Nuclear Information System (INIS)

    The viscosity of benzene is described by the Arrhenius equation ή = const. exp (E/kBT), where E is the activation energy for viscous flow. The viscosity of toluene, however, follows this law only in the higher temperature region of its liquid range, i.e. above the Arrhenius temperature TA. In the whole normal liquid range the benzene molecule is supposed to be able to rotate many times about at least two symmetry axes between translational jumps. Davies and Matheson suggest that the onset of non-Arrhenius viscosity behaviour in toluene occurs at that temperature at which rotation about two axes becomes restricted, while rotation about the third remains free. Inelastic scattering experiments of slow neutrons have been performed on the two substances using a time-of-flight spectrometer for cold neutrons with an energy resolution of 12 %. The quasi-elastic scattering has been studied for small momentum transfer as a function of temperature. Diffusion coefficients have been determined assuming a Lorentzian cross-section. The temperature dependence of the diffusion coefficient for benzene follows an exponential law, but the coefficient is a few times larger than the macroscopic coefficient, showing that a large amount of rotational diffusion exists. For toluene there is a change in the temperature dependence of the coefficient at about TA. This is taken as an indication of a change in the number of degrees of rotational freedom of the toluene molecule around TA. The methyl group in toluene has a low barrier to rotation (≲500 cal/mole). Therefore the hindered rotation levels of the methyl group as well as molecular rotation will contribute significantly to the inelastic scattering spectrum which overlaps the quasi-elastic peak. Th e inelastic component is subtracted by extrapolation but the possible contribution of the CH3 rotation to the quasi-elastic peak itself is neglected. (author)

  4. Velocity-dependent emission factors of benzene, toluene and C{sub 2}-benzenes of a passenger car equipped with and without a regulated 3-way catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Heeb, N.V.; Forss, A.-M.; Bach, C.; Mattrel, P. [Swiss Federal Laboratories for Materials Testing and Research, Duebendorf (Switzerland)

    2000-07-01

    Time-resolved chemical ionization mass spectrometry (Cl-MS) has been used to investigate the velocity-dependent emission factors for benzene, toluene, the C{sub 2}-benzenes (xylenes and ethyl benzene) and nitrogen monoxide of a gasoline-driven passenger car (1.4 l, model year 1995) driven with or without catalytic exhaust gas treatment. A set of seven different driving cycles - including the European Driving Cycle (EDC), the US Urban (FTP 75) and the Highway driving cycles - with a total driving time of 12,000 s have been studied. From the obtained emission data, two sets of 15,300 and 17,200 data points which represent transient driving in the velocity range of 0-150 km h{sup -1} and in an acceleration window of - 2-3 m s{sup -2} were explored to gain velocity-dependent emission factors. The passenger car, equipped with a regulated rhodium-platinum based three-way catalyst, showed optimal conversion efficiency (> 95%) for benzene in the velocity range of 60-120 km h{sup -1}. The conversion of benzene was reduced (< 80%) when driving below 50 km h{sup -1} and the BTXE emissions significantly increased when driven at higher speed and engine load (> 130 km h{sup -1}). Whereas the conversion efficiency for the class of C{sub 2}-benzenes was reduced to 10%, no net conversion could be found for toluene and benzene when driven above 130 km h{sup -1}. In contrast, the benzene and toluene emissions exceeded those of the untreated exhaust gas in the velocity range of 130-150 km h{sup -1} by 50-92% and by 10-34%, respectively. Thus, benzene and toluene were formed across the examined three-way catalyst if the engine is operated for an extended time in a fuel-rich mode (lambda < 1). (author)

  5. Metabolites from Alternaria Fungi and Their Bioactivities

    Directory of Open Access Journals (Sweden)

    Ligang Zhou

    2013-05-01

    Full Text Available Alternaria is a cosmopolitan fungal genus widely distributing in soil and organic matter. It includes saprophytic, endophytic and pathogenic species. At least 268 metabolites from Alternaria fungi have been reported in the past few decades. They mainly include nitrogen-containing metabolites, steroids, terpenoids, pyranones, quinones, and phenolics. This review aims to briefly summarize the structurally different metabolites produced by Alternaria fungi, as well as their occurrences, biological activities and functions. Some considerations related to synthesis, biosynthesis, production and applications of the metabolites from Alternaria fungi are also discussed.

  6. Atomic Structure of Benzene Which Accounts for Resonance Energy

    CERN Document Server

    Heyrovska, Raji

    2008-01-01

    Benzene is a hexagonal molecule of six carbon atoms, each of which is bound to six hydrogen atoms. The equality of all six CC bond lengths, despite the alternating double and single bonds, and the surplus (resonance) energy, led to the suggestion of two resonanting structures. Here, the new atomic structure shows that the bond length equality is due to three carbon atoms with double bond radii bound to three other carbon atoms with resonance bond radii (as in graphene). Consequently, there are two kinds of CH bonds of slightly different lengths. The bond energies account for the resonance energy.

  7. 4-Benzene­sulfonamido­benzoic acid

    OpenAIRE

    Sharif, Hafiz Muhammad Adeel; Dong, Gui-Ying; Arshad, Muhammad Nadeem; Khan, Islam Ullah

    2009-01-01

    In the mol­ecule of the title sulfonamide compound, C13H11NO4S, the dihedral angle between the planes of the benzene ring and the carboxyl substituent group is 6.7 (4)°. The two aromatic rings are inclined at 45.36 (15)° to one another. In the crystal, adjacent mol­ecules are linked via classical inter­molecular N—H⋯O and O—H⋯O, and non-classical C—H⋯O hydrogen bonds, which stabilize the crystal structure.

  8. 4-Benzene­sulfonamido­benzoic acid

    Science.gov (United States)

    Sharif, Hafiz Muhammad Adeel; Dong, Gui-Ying; Arshad, Muhammad Nadeem; Khan, Islam Ullah

    2009-01-01

    In the mol­ecule of the title sulfonamide compound, C13H11NO4S, the dihedral angle between the planes of the benzene ring and the carboxyl substituent group is 6.7 (4)°. The two aromatic rings are inclined at 45.36 (15)° to one another. In the crystal, adjacent mol­ecules are linked via classical inter­molecular N—H⋯O and O—H⋯O, and non-classical C—H⋯O hydrogen bonds, which stabilize the crystal structure. PMID:21578816

  9. Alkylation of benzene with normal olefins from coker distillate

    Energy Technology Data Exchange (ETDEWEB)

    Aboul-Gheit, A.K.; Moustafa, O.F.; Habbib, R.M.

    1985-10-01

    The normal olefins separated from a coker distillate were used to alkylate benzene on catalysts containing silicotungstic acid supported on silica, silica-alumina and activated natural clays. The alkylation activity was found to increase as the surface area and silica/alumina ratio of the catalysts increase, irrespective of the support texture. The activation energy of the reaction was very low (proportional3 k cal mol/sup -1/), assuming catalytic intraparticle diffusion limitation. Equilibrium shift towards dealkylation was observed beyond 300/sup 0/C. (orig.).

  10. Bis[diethyl(hydroxyammonium] benzene-1,4-dicarboxylate

    Directory of Open Access Journals (Sweden)

    De-Ming Xie

    2010-08-01

    Full Text Available In the centrosymmetric title compound, 2C4H12NO+·C8H4O42−, two N,N-diethyl(hydroxyammonium cations are linked to a benzene-1,4-dicarboxylate dianion by a combination of O—H...O and N—H...O hydrogen bonds, which can be described in graph-set terminology as R22(7. The crystal structure is further stabilized by C—H...O hydrogen bonds, leading to the fomation of a ribbon-like network.

  11. Exposition by inhalation to the benzene, toluene, ethyl-benzene and xylenes (BTEX) in the air. Sources, measures and concentrations; Exposition par inhalation au benzene, toluene, ethylbenzene et xylenes (BTEX) dans l'air. Source, mesures et concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Del Gratta, F.; Durif, M.; Fagault, Y.; Zdanevitch, I

    2004-12-15

    This document presents the main techniques today available to characterize the benzene, toluene, ethyl-benzene and xylene (BTEX) concentrations in the air for different contexts: urban and rural areas or around industrial installations but also indoor and occupational area. It provides information to guide laboratories and research departments. A synthesis gives also the main emissions sources of these compounds as reference concentrations measured in different environments. (A.L.B.)

  12. Endocrine-mediated effects of two benzene related compounds, 1-chloro-4-(chloromethyl)benzene and 1,3-diethyl benzene, based on subacute oral toxicity studies using rats.

    Science.gov (United States)

    Yamasaki, Kanji; Ishii, Satoko; Kikuno, Tsukasa; Minobe, Yasushi

    2012-08-01

    The purpose of this study was to investigate the endocrine-mediated effects of the benzene-related compounds with reference to Organization for Economic Co-operation and Development (OECD) Test Guideline No. 407. Rats were orally gavaged with 0, 10, 50, and 250 mg/kg/day of 1-chloro-4-(chloromethyl)benzene, and 0, 25, 150, and 1000 mg/kg/day of 1,3-diethyl benzene for at least 28 days, beginning at 8 weeks of age. Thyroid dysfunction was observed in rats given the 1,3-diethyl benzene. Serum T4 values increased in all groups of male rats and in the 1000 mg/kg group of female rats, and TSH values also increased in the 1000 mg/kg groups of both sexes after 28 days' administration. Decreased T3 values were observed in the 1000 mg/kg group of female rats after 28 days' administration, and hormone values increased in the 1000 mg/kg groups of both sexes after the 14-day recovery period. In addition, thyroid weight increased in the 1000 mg/kg groups and thyroid follicular cell hyperplasia was detected in one male rat from the 1000 mg/kg group after 28 days' administration. Endocrine-mediated effects, including thyroid dysfunction were not observed in any groups of rats treated with 1-chloro-4-(chloromethyl)benzene. Our results indicated that endocrine-mediated effects such as thyroid dysfunction were associated with some benzene-related compounds. PMID:22643015

  13. Aggregation of Benzene Molecules with Molecules of Methanol and Formic Acid

    International Nuclear Information System (INIS)

    Calculations and experimental studies of Raman scattering spectra show that there is a dimeric aggregation of benzene molecules with the molecule of methyl alcohol with the use of π-electrons of the benzene ring. In this process, the H-active hydrogen atom of O-H group is oriented to the edge of the benzene ring (a distance along the normal to the plane of the benzene ring is 2.850 A). The unusual position of the H-active hydrogen atom is conditioned by the interaction of two hydrogen atoms of the alcohols methyl group with π-electrons of the benzene ring. In Raman scattering spectra, the aggregation of molecules in the liquid state of the substance leads to a broadening of the band of full-symmetric vibrations with the maximum at 992 cm-1, as well as to a shift of this band toward lower frequencies by ∼ 1 cm-1. The band at 992 cm-1 is narrowed more than twice at the strong dilution of the benzene-methyl alcohol mixture by a large amount of heptane. The aggregation of benzene molecules takes place also with the molecules of formic acid with the use of π-electrons of the benzene ring. As in the case of the benzene-methyl alcohol mixture, the H-active hydrogen atom of O-H group of the acid is shifted toward the edge of the benzene ring. The energy of the benzene-formic acid dimerization is 9.2 kJ/mole.

  14. Impact of a new gasoline benzene regulation on ambient air pollutants in Anchorage, Alaska

    Science.gov (United States)

    Yano, Yuriko; Morris, Stephen S.; Salerno, Christopher; Schlapia, Anne M.; Stichick, Mathew

    2016-05-01

    The purpose of this study was to quantify the impact of a new U.S. Environmental Protection Agency (EPA) standard that limits the amount of benzene allowed in gasoline on ambient benzene concentrations. This new standard, together with two companion regulations that limit cold-temperature automotive emissions and the permeability of portable fuel containers, was expected to lower the levels of ambient benzene and other volatile organic compounds (VOCs) nationwide. In this study the impact of the gasoline benzene standard was evaluated in Anchorage, Alaska in a two-phase ambient air monitoring study conducted before and after the new gasoline standard was implemented. Gasoline sold by Anchorage retailers was also evaluated in each phase to determine the content of benzene and other gasoline components. The average benzene content in Anchorage gasoline was reduced by 70%, from 5.05% (w/w) to 1.53% (w/w) following the implementation of the standard. The annual mean ambient benzene concentration fell by 51%, from 0.99 ppbv in Phase 1 to 0.49 ppbv in Phase 2. Analysis suggests the change in gasoline benzene content alone reduced benzene emissions by 46%. The changes in toluene, ethylbenzene, and xylene content in gasoline between Phase 1 and 2 were relatively small and the differences in the mean ambient concentrations of these compounds between phases were modest. Our results suggest that cold winter communities in high latitude and mountainous regions may benefit more from the gasoline benzene standard because of high benzene emissions resulting from vehicle cold start and a tendency to develop atmospheric stagnation conditions in the winter.

  15. A highly sensitive electrochemical sensor for simultaneous determination of hydroquinone and bisphenol A based on the ultrafine Pd nanoparticle@TiO{sub 2} functionalized SiC

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Long [School of Chemical Science and Technology, Yunnan University, Kunming 650091 (China); Zhao, Hui [Laboratory for Conservation and Utilization of Bio-resource, Yunnan University, Kunming 650091 (China); Fan, Shuangmei; Li, Bingchan [School of Chemical Science and Technology, Yunnan University, Kunming 650091 (China); Li, Can-Peng, E-mail: lcppp1974@sina.com [School of Chemical Science and Technology, Yunnan University, Kunming 650091 (China)

    2014-12-10

    Graphical abstract: The illustration of Pd@TiO{sub 2}–SiC nanohybrids simultaneous sensing hydroquinone and bisphenol A by an electrochemical strategy. - Highlights: • TiO{sub 2}–SiC was successfully prepared by a facile generic in situ growth strategy. • Ultrafine Pd NPs with a uniform size of ∼2.3 nm monodispersed on TiO{sub 2}–SiC surface. • Electrochemical simultaneous determination of HQ and BPA was established. • Ultrafine metal NPs@metal oxide–SiC may be extended to other applications. - Abstract: A titanium dioxide–silicon carbide nanohybrid (TiO{sub 2}–SiC) with enhanced electrochemical performance was successfully prepared through a facile generic in situ growth strategy. Monodispersed ultrafine palladium nanoparticles (Pd NPs) with a uniform size of ∼2.3 nm were successfully obtained on the TiO{sub 2}–SiC surface via a chemical reduction method. The Pd-loaded TiO{sub 2}–SiC nanohybrid (Pd@TiO{sub 2}–SiC) was characterized by transmission electron microscopy and X-ray diffractometry. A method for the simultaneous electrochemical determination of hydroquinone (HQ) and bisphenol A (BPA) using a Pd@TiO{sub 2}–SiC nanocomposite-modified glassy carbon electrode was established. Utilizing the favorable properties of Pd NPs, the Pd@TiO{sub 2}–SiC nanohybrid-modified glassy carbon electrode exhibited electrochemical performance superior to those of TiO{sub 2}–SiC and SiC. Differential pulse voltammetry was successfully used to simultaneously quantify HQ and BPA within the concentration range of 0.01–200 μM under optimal conditions. The detection limits (S/N = 3) of the Pd@TiO{sub 2}–SiC nanohybrid electrode for HQ and BPA were 5.5 and 4.3 nM, respectively. The selectivity of the electrochemical sensor was improved by introducing 10% ethanol to the buffer medium. The practical application of the modified electrode was demonstrated by the simultaneous detection of HQ and BPA in tap water and wastewater samples. The simple

  16. A highly sensitive electrochemical sensor for simultaneous determination of hydroquinone and bisphenol A based on the ultrafine Pd nanoparticle@TiO2 functionalized SiC

    International Nuclear Information System (INIS)

    Graphical abstract: The illustration of Pd@TiO2–SiC nanohybrids simultaneous sensing hydroquinone and bisphenol A by an electrochemical strategy. - Highlights: • TiO2–SiC was successfully prepared by a facile generic in situ growth strategy. • Ultrafine Pd NPs with a uniform size of ∼2.3 nm monodispersed on TiO2–SiC surface. • Electrochemical simultaneous determination of HQ and BPA was established. • Ultrafine metal NPs@metal oxide–SiC may be extended to other applications. - Abstract: A titanium dioxide–silicon carbide nanohybrid (TiO2–SiC) with enhanced electrochemical performance was successfully prepared through a facile generic in situ growth strategy. Monodispersed ultrafine palladium nanoparticles (Pd NPs) with a uniform size of ∼2.3 nm were successfully obtained on the TiO2–SiC surface via a chemical reduction method. The Pd-loaded TiO2–SiC nanohybrid (Pd@TiO2–SiC) was characterized by transmission electron microscopy and X-ray diffractometry. A method for the simultaneous electrochemical determination of hydroquinone (HQ) and bisphenol A (BPA) using a Pd@TiO2–SiC nanocomposite-modified glassy carbon electrode was established. Utilizing the favorable properties of Pd NPs, the Pd@TiO2–SiC nanohybrid-modified glassy carbon electrode exhibited electrochemical performance superior to those of TiO2–SiC and SiC. Differential pulse voltammetry was successfully used to simultaneously quantify HQ and BPA within the concentration range of 0.01–200 μM under optimal conditions. The detection limits (S/N = 3) of the Pd@TiO2–SiC nanohybrid electrode for HQ and BPA were 5.5 and 4.3 nM, respectively. The selectivity of the electrochemical sensor was improved by introducing 10% ethanol to the buffer medium. The practical application of the modified electrode was demonstrated by the simultaneous detection of HQ and BPA in tap water and wastewater samples. The simple and straightforward strategy presented in this paper are important

  17. Chemical accuracy from quantum Monte Carlo for the benzene dimer.

    Science.gov (United States)

    Azadi, Sam; Cohen, R E

    2015-09-14

    We report an accurate study of interactions between benzene molecules using variational quantum Monte Carlo (VMC) and diffusion quantum Monte Carlo (DMC) methods. We compare these results with density functional theory using different van der Waals functionals. In our quantum Monte Carlo (QMC) calculations, we use accurate correlated trial wave functions including three-body Jastrow factors and backflow transformations. We consider two benzene molecules in the parallel displaced geometry, and find that by highly optimizing the wave function and introducing more dynamical correlation into the wave function, we compute the weak chemical binding energy between aromatic rings accurately. We find optimal VMC and DMC binding energies of -2.3(4) and -2.7(3) kcal/mol, respectively. The best estimate of the coupled-cluster theory through perturbative triplets/complete basis set limit is -2.65(2) kcal/mol [Miliordos et al., J. Phys. Chem. A 118, 7568 (2014)]. Our results indicate that QMC methods give chemical accuracy for weakly bound van der Waals molecular interactions, comparable to results from the best quantum chemistry methods. PMID:26374029

  18. Chemical accuracy from quantum Monte Carlo for the benzene dimer

    International Nuclear Information System (INIS)

    We report an accurate study of interactions between benzene molecules using variational quantum Monte Carlo (VMC) and diffusion quantum Monte Carlo (DMC) methods. We compare these results with density functional theory using different van der Waals functionals. In our quantum Monte Carlo (QMC) calculations, we use accurate correlated trial wave functions including three-body Jastrow factors and backflow transformations. We consider two benzene molecules in the parallel displaced geometry, and find that by highly optimizing the wave function and introducing more dynamical correlation into the wave function, we compute the weak chemical binding energy between aromatic rings accurately. We find optimal VMC and DMC binding energies of −2.3(4) and −2.7(3) kcal/mol, respectively. The best estimate of the coupled-cluster theory through perturbative triplets/complete basis set limit is −2.65(2) kcal/mol [Miliordos et al., J. Phys. Chem. A 118, 7568 (2014)]. Our results indicate that QMC methods give chemical accuracy for weakly bound van der Waals molecular interactions, comparable to results from the best quantum chemistry methods

  19. Chemical accuracy from quantum Monte Carlo for the Benzene Dimer

    CERN Document Server

    Azadi, Sam

    2015-01-01

    We report an accurate study of interactions between Benzene molecules using variational quantum Monte Carlo (VMC) and diffusion quantum Monte Carlo (DMC) methods. We compare these results with density functional theory (DFT) using different van der Waals (vdW) functionals. In our QMC calculations, we use accurate correlated trial wave functions including three-body Jastrow factors, and backflow transformations. We consider two benzene molecules in the parallel displaced (PD) geometry, and find that by highly optimizing the wave function and introducing more dynamical correlation into the wave function, we compute the weak chemical binding energy between aromatic rings accurately. We find optimal VMC and DMC binding energies of -2.3(4) and -2.7(3) kcal/mol, respectively. The best estimate of the CCSD(T)/CBS limit is -2.65(2) kcal/mol [E. Miliordos et al, J. Phys. Chem. A 118, 7568 (2014)]. Our results indicate that QMC methods give chemical accuracy for weakly bound van der Waals molecular interactions, compar...

  20. Local Field Factors and Dielectric Properties of Liquid Benzene.

    Science.gov (United States)

    Davari, Nazanin; Daub, Christopher D; Åstrand, Per-Olof; Unge, Mikael

    2015-09-01

    Local electric field factors are calculated for liquid benzene by combining molecular dynamic simulations with a subsequent force-field model based on a combined charge-transfer and point-dipole interaction model for the local field factor. The local field factor is obtained as a linear response of the local field to an external electric field, and the response is calculated at frequencies through the first absorption maximum. It is found that the largest static local field factor is around 2.4, while it is around 6.4 at the absorption frequency. The linear susceptibility, the dielectric constant, and the first absorption maximum of liquid benzene are also studied. The electronic contribution to the dielectric constant is around 2.3 at zero frequency, in good agreement with the experimental value around 2.2, while it increases to 6.3 at the absorption frequency. The π → π* excitation energy is around 6.0 eV, as compared to the gas-phase value of around 6.3 eV, while the experimental values are 6.5 and 6.9 eV for the liquid and gas phase, respectively, demonstrating that the gas-to-liquid shift is well-described. PMID:26241379

  1. Diffusion and adsorption of benzene in Regina clay

    International Nuclear Information System (INIS)

    Surface or near-surface spills of hydrocarbons such as gasoline and diesel often occur in clay soils which are fractured and unsaturated. For cost-effective remediation, the extent of contamination and the distribution of the various phases should be determined before the development of remediation methods. The four volatile compounds that are commonly associated with gasoline leaking from underground fuel storage tanks are benzene, toluene, ethlybenzene and xylene. Existing diffusion test methods have been used successfully for inorganic species, but the successful application of these methods to volatile organic compounds is limited. The main difficulty with experiments using volatile organics is that there is a need for careful sample handling and sensitive analytical methods to accurately measure the aqueous concentration. Work was carried out to develop an apparatus that could be used to measure the diffusion and adsorption of volatile organics in clay. The best visual fit to the experimental data for the single reservoir test was an effective diffusion coefficient of 0.01 mL/g, and an adsorption coefficient of 0.1 mL/g. Based on diffusion cell tests, there are relatively low levels of retardation for benzene as it moves in clay soils with low organic carbon content. The implications for remediation are summarized. 28 refs., 16 figs., 5 tabs

  2. Irradiated Benzene Ice Provides Clues to Meteoritic Organic Chemistry

    Science.gov (United States)

    Callahan, Michael Patrick; Gerakines, Perry Alexander; Martin, Mildred G.; Hudson, Reggie L.; Peeters, Zan

    2013-01-01

    Aromatic hydrocarbons account for a significant portion of the organic matter in carbonaceous chondrite meteorites, as a component of both the low molecular weight, solvent-extractable compounds and the insoluble organic macromolecular material. Previous work has suggested that the aromatic compounds in carbonaceous chondrites may have originated in the radiation-processed icy mantles of interstellar dust grains. Here we report new studies of the organic residue made from benzene irradiated at 19 K by 0.8 MeV protons. Polyphenyls with up to four rings were unambiguously identified in the residue by gas chromatography-mass spectrometry. Atmospheric pressure photoionization Fourier transform mass spectrometry was used to determine molecular composition, and accurate mass measurements suggested the presence of polyphenyls, partially hydrogenated polyphenyls, and other complex aromatic compounds. The profile of low molecular weight compounds in the residue compared well with extracts from the Murchison and Orgueil meteorites. These results are consistent with the possibility that solid phase radiation chemistry of benzene produced some of the complex aromatics found in meteorites.

  3. Thermodynamic investigation of the binary system of ethanol + benzene

    International Nuclear Information System (INIS)

    The molar heat capacity of the binary system ethanol + benzene was measured by an adiabatic calorimeter in the temperature range from 80 to 320 K. The glass transition and phase transitions of the mixture were determined based on the curve of the heat capacity with respect to temperature. The glass transition occurred at 97.536 K, the enthalpy and entropy of the glass transition were calculated to be 1.796 kJ mol-1, 18.414 J mol-1 K-1, respectively. The phase transitions took place in temperature ranges 115.875-128.400, 146.778-159.015 and 256.645-274.981 K corresponding to the solid-solid phase transition of ethanol, solid-liquid phase transition of ethanol and solid-liquid phase transition of benzene, respectively. The corresponding enthalpies and entropies of the phase transition were calculated to be -1.266 kJ mol-1, -10.745 J K-1 mol-1; 2.166 kJ mol-1, 13.818 J K-1 mol-1; 5.390 kJ mol-1, 19.856 J K-1 mol-1, respectively. The thermodynamic functions and the excess thermodynamic functions of the mixture relative to standard temperature 298.15 K were derived based on the relationships of the thermodynamic functions and the function of the measured heat capacity with respect to temperature

  4. Sonochemical treatment of benzene/toluene contaminated wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Thoma, G.; Gleason, M. [Univ. of Arkansas, Fayetteville, AR (United States). Dept. of Chemical Engineering; Popov, V. [Scientific Production Association Typhoon, Obninsk (Russian Federation). Inst. of Experimental Meterology

    1998-12-31

    Studies of the destruction of benzene and toluene in water were undertaken using ultrasonic irradiation in a parallel place Near Field Acoustic Processor (NAP). This magnetostrictive system is capable of degrading both benzene and toluene in a continuous stirred tank reactor configuration. The reaction kinetics were characterized by first order rate constants for the disappearance of the parent compound; these ranged from 2.7 {times} 1{sup {minus}3} to 3.7 {times} 10{sup {minus}2} mm{sup {minus}1} over an applied power density range of 0.6 to 3.6 watt mL{sup {minus}1} and target concentration of approximately 25 to 900 {micro}M. The rate constant is shown to be inversely proportional to the target compound concentration, indicating higher order reaction kinetics. The conversion efficiency for the system was characterized through the G efficiency commonly used in radiation chemistry. The G efficiency ranged between 4 {times} 10{sup {minus}5} to 2.2 {times} 10{sup {minus}4} molecules destroyed per 100 eV of electrical energy drawn from the wall outlet. These values are comparable to those of other advanced oxidation processes. Suggestions are made regarding methods to improve this technology.

  5. Alkylation of Benzene with Propylene Catalyzed by Ionic Liquids

    Institute of Scientific and Technical Information of China (English)

    Sun Xuewen; Zhao Suoqi

    2006-01-01

    The alkylation of benzene with propylene catalyzed by ionic liquids to obtain cumene was investigated. Propylene conversion and cumene selectivity under mild reaction conditions were improved greatly after the ionic liquid was modified with HCl. Under the conditions of 20 oC, 0.1MPa, 5 min of reaction time, and a molar ratio of benzene to propylene of 10:1, propylene conversion increased from 83.6% to 100%, and cumene selectivity increased from 90.86% to 98.47%. In addition, it was found that the reaction could be carried out in two different stages so as to obtain a better result. At the first stage, the key reaction was alkylation and a higher propylene conversion was obtained at a lower temperature;At the second stage, the key reaction was transalkylation and a higher temperature was used to improve cumene selectivity. The reaction temperature, pressure and the amount of catalyst used in this work were lower than those used in traditional alkylation processes.

  6. Separation of Benzene and Cyclohexane by Batch Extractive Distillation

    Institute of Scientific and Technical Information of China (English)

    XU Jiao; ZHANG Weijiang; GUI Xia

    2007-01-01

    Azeotropic liquid mixture cannot be separated by conventional distillation. But extractive distillation or combination of the two can be valid for them. An experiment to separate benzene and cyclohexane by batch extractive distillation was carried out with N, N-dimethylformide (DMF), dimethyl sulfoxide (DMSO) and their mixture as extractive solvent. The effect of the operation parameterssuch as solvent flow rate and reflux ratio on the separation was studied under the same operating conditions. The results show that the separation effect was improved with the increase of solvent flow rate and the reflux ratio; all the three extractive solvents can separate benzene and cyclohexane, with DMF being the most efficient one, the mixture the second, and DMSO the least. In the experiment the best operation conditions are with DMF as extractive solvent, the solvent flow rate being 12.33 mL/min, and the reflux ratio being 6. As a result, we can get cyclohexane from the top of tower with the average product content being 86.98%, and its recovering ratio being 83.10%.

  7. Effect of substrate interaction on oxidation of methane and benzene in enriched microbial consortia from landfill cover soil.

    Science.gov (United States)

    Lee, Eun-Hee; Park, Hyunjung; Cho, Kyung-Suk

    2011-01-01

    The interaction of methane and benzene during oxidation in enriched methane-oxidizing consortium (MOC) and in benzene-oxidizing consortium (BOC) from landfill cover soil was characterized. Oxidation of both methane and benzene occurred in the MOC due to the coexistence of bacteria responsible for benzene oxidation, as well as methanotrophs, whereas in the BOC, only benzene was oxidized, not methane. Methane oxidation rates in the MOC were decreased with increasing benzene/methane ratio (mol/mol), indicating its methane oxidation was inhibited by the benzene coexistence. Benzene oxidation rates in the MOC, however, were increased with increasing benzene/methane ratio. The benzene oxidation in the BOC was not affected by the coexistence of methane or by the ratio of methane/benzene ratio (mol/mol). No effect of methane or benzene was found on the dynamics of functional genes, such as particulate methane monooxygenase and toluene monooxygenase, in association with oxidation of methane and benzene in the MOC and BOC. PMID:21847790

  8. Secondary metabolites from marine Penicillium brevicompactum

    OpenAIRE

    2006-01-01

    In a screening of Basidiomycete cultures isolated from marine invertebrates collected along the Chilean coastline for the production of antibiotics we identified a Penicillium brevicompactum strain as a producer of metabolites inhibiting the growth of bacteria and fungi. Bioactivity guided purification resulted in the isolation of four known metabolites. Their structures were elucidated by spectroscopic methods.

  9. Variability of benzene exposure among filling station attendants; Variabilita` dell`esposizione a benzene tra gli addetti all`erogazione di carburanti

    Energy Technology Data Exchange (ETDEWEB)

    Carere, A.; Iacovella, N.; Turrio Baldassarri, L. [Istituto Superiore di Sanita`, Rome (Italy). Lab. di Tossicologia Comparata ed Ecotossicologia; Fuselli, S.; Iavarone, I.; Lagorio, S.; Proietto, A.R. [Istituto Superiore di Sanita`, Rome (Italy). Lab. di Igiene Ambientale

    1996-12-01

    A monitoring survey of filling station attendants aimed at identifying sources of variability of exposure to benzene and other aromatics was carried out. Concurrent samples of the worker`s breathing zone air, atmospheric air in the service station proximity, and gasoline were collected, along with information about daily workloads and other exposure-related factors. Benzene personal exposure was characterised by a small between-worker variability and a predominant within-worker variance component. Such elevated day-to-day variability yields to imprecise estimates of mean personal exposure. Almost 70% of the overall personal exposure variance was explained by a model including daily benzene from dispensed fuel, presence of a shelter over the refueling area, amount of fuel supplied to the station if a delivery occurred, and background atmospheric benzene concentration.

  10. Benzene bioremediation using cow dung microflora in two phase partitioning bioreactor

    International Nuclear Information System (INIS)

    Bioremediation of benzene has been carried out using cow dung microflora in a bioreactor. The bioremediation of benzene under the influence of cow dung microflora was found to be 100% and 67.5%, at initial concentrations of 100 mg/l and 250 mg/l within 72 h and 168 h respectively; where as at higher concentration (500 mg/l), benzene was found to be inhibitory. Hence the two phase partitioning bioreactor (TPPB) has been designed and developed to carryout biodegradation at higher concentration. In TPPB 5000 mg/l benzene was biodegraded up to 50.17% over a period of 168 h. Further the Pseudomonas putida MHF 7109 was isolated from cow dung microflora as potential benzene degrader and its ability to degrade benzene at various concentrations was evaluated. The data indicates 100%, 81% and 65% degradation at the concentrations of 50 mg/l, 100 mg/l, 250 mg/l within the time period of 24 h, 96 h and 168 h respectively. The GC-MS data also shows the presence of catechol and 2-hydroxymuconic semialdehyde, which confirms the established pathway of benzene biodegradation. The present research proves the potential of cow dung microflora as a source of biomass for benzene biodegradation in TPPB.

  11. 40 CFR 721.1230 - Benzene, ethenyl-, ar-bromo derivatives.

    Science.gov (United States)

    2010-07-01

    ... removed from a container that has held the substance, unless the container is empty as defined in 40 CFR... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Benzene, ethenyl-, ar-bromo... Specific Chemical Substances § 721.1230 Benzene, ethenyl-, ar-bromo derivatives. (a) Chemical substance...

  12. 78 FR 25476 - Agency Information Collection Activities; Submission for OMB Review; Comment Request; Benzene...

    Science.gov (United States)

    2013-05-01

    ... information, see the related notice published in the Federal Register on February 28, 2013 (78 FR 13707...; Benzene Standard ACTION: Notice. SUMMARY: On April 30, 2013, the Department of Labor (DOL) will submit the..., ``Benzene Standard,'' to the Office of Management and Budget (OMB) for review and approval for continued...

  13. 40 CFR 721.1240 - Benzene, (2-bromoethyl)-, ar-bromo derivatives.

    Science.gov (United States)

    2010-07-01

    ... that has held the substance, unless the container is empty as defined in 40 CFR 261.7(b)(3); any... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Benzene, (2-bromoethyl)-, ar-bromo... Specific Chemical Substances § 721.1240 Benzene, (2-bromoethyl)-, ar-bromo derivatives. (a)...

  14. Benzene emission from the actual car fleet in relation to petrol composition in Denmark

    International Nuclear Information System (INIS)

    The present study covers an investigation of the trends in air pollution levels of benzene in Danish cities and their relationship with the benzene content in petrol. Petrol samples from the two refineries in Denmark as well as sold petrol from some representative Danish petrol stations were analysed. The benzene content in Danish petrol was reduced from 3.5% for 95 octane prior to 1995 to approx. 2% in 1995 and further to 1% in 1998. Air quality measurements of aromatic VOC are available from two Danish cities; Copenhagen since 1994 and Odense since 1997. Measurements of benzene, CO and NOx from these two locations were analysed using the Operational Street Pollution Model (OSPM) and trends in the actual emissions of these pollutants were determined. It is shown that the decrease in both the concentration levels and in the emissions was significantly larger for benzene than for CO and NOx. The decreasing trends of NOx and CO could be explained by the increasing fraction of petrol-fuelled vehicles with three way catalysts (TWC). The much steeper decreasing trend for benzene can most likely be attributed to a combination of the effect of the increasing share of the TWC vehicles and a simultaneous reduction of benzene content in Danish petrol. The reduction of benzene concentrations and emissions is observed despite that the total amount of aromatics in petrol has increased slightly in the same period. (Author)

  15. Genotoxic and histotoxic effects of air pollutants at a benzene station on albino rats

    Directory of Open Access Journals (Sweden)

    Mohamed Abousalem

    2014-02-01

    Conclusions: The findings of the present study indicated that benzene exposure may lead to toxic effects including, genotoxicities and histotoxicities. In order to minimize the predicted toxic effect of occupational exposure to benzene the strict protective measures should be put in consideration. [Int J Basic Clin Pharmacol 2014; 3(1.000: 144-150

  16. Benzene emission from the actual car fleet in relation to petrol composition in Denmark

    Science.gov (United States)

    Palmgren, Finn; Hansen, Asger B.; Berkowicz, Ruwim; Skov, Henrik

    The present study covers an investigation of the trends in air pollution levels of benzene in Danish cities and their relationship with the benzene content in petrol. Petrol samples from the two refineries in Denmark as well as sold petrol from some representative Danish petrol stations were analysed. The benzene content in Danish petrol was reduced from 3.5% for 95 octane prior to 1995 to approx. 2% in 1995 and further to 1 % in 1998. Air quality measurements of aromatic VOC are available from two Danish cities; Copenhagen since 1994 and Odense since 1997. Measurements of benzene, CO and NO x from these two locations were analysed using the Operational Street Pollution Model (OSPM) and trends in the actual emissions of these pollutants were determined. It is shown that the decrease in both the concentration levels and in the emissions was significantly larger for benzene than for CO and NO x. The decreasing trends of NO x and CO could be explained by the increasing fraction of petrol-fuelled vehicles with three way catalysts (TWC). The much steeper decreasing trend for benzene can most likely be attributed to a combination of the effect of the increasing share of the TWC vehicles and a simultaneous reduction of benzene content in Danish petrol. The reduction of benzene concentrations and emissions is observed despite that the total amount of aromatics in petrol has increased slightly in the same period.

  17. Homolytic iodination and nitration of some benzene derivatives in the gas phase

    International Nuclear Information System (INIS)

    Two gas phase reactions, involving the iodination and nitration of benzene derivatives, are described. The experimental techniques of the apparatus and the methods used are outlined. The kinetic H/D isotope effect in the gas phase nitration of benzene with NO2 is determined. (C.F.)

  18. Current understanding of the mechanism of benzene-induced leukemia in humans: implications for risk assessment

    Science.gov (United States)

    McHale, Cliona M.; Zhang, Luoping; Smith, Martyn T.

    2012-01-01

    Benzene causes acute myeloid leukemia and probably other hematological malignancies. As benzene also causes hematotoxicity even in workers exposed to levels below the US permissible occupational exposure limit of 1 part per million, further assessment of the health risks associated with its exposure, particularly at low levels, is needed. Here, we describe the probable mechanism by which benzene induces leukemia involving the targeting of critical genes and pathways through the induction of genetic, chromosomal or epigenetic abnormalities and genomic instability, in a hematopoietic stem cell (HSC); stromal cell dysregulation; apoptosis of HSCs and stromal cells and altered proliferation and differentiation of HSCs. These effects modulated by benzene-induced oxidative stress, aryl hydrocarbon receptor dysregulation and reduced immunosurveillance, lead to the generation of leukemic stem cells and subsequent clonal evolution to leukemia. A mode of action (MOA) approach to the risk assessment of benzene was recently proposed. This approach is limited, however, by the challenges of defining a simple stochastic MOA of benzene-induced leukemogenesis and of identifying relevant and quantifiable parameters associated with potential key events. An alternative risk assessment approach is the application of toxicogenomics and systems biology in human populations, animals and in vitro models of the HSC stem cell niche, exposed to a range of levels of benzene. These approaches will inform our understanding of the mechanisms of benzene toxicity and identify additional biomarkers of exposure, early effect and susceptibility useful for risk assessment. PMID:22166497

  19. 46 CFR Appendix B to Subpart C to... - Substance Technical Guidelines, Benzene

    Science.gov (United States)

    2010-10-01

    ...) Benzene is classified as a flammable liquid for the purpose of conforming to the requirements of 49 CFR... locations for the purposes of conforming to the requirements of 46 CFR parts 30 through 40, 151, and 153.... (Benzin, petroleum benzin, and benzine do not contain benzene). (2) Formula: C6 H6 (CAS Registry...

  20. Benzene bioremediation using cow dung microflora in two phase partitioning bioreactor

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Dipty [Environmental Biotechnology Laboratory, Department of Life Sciences, University of Mumbai, Vidyanagari Campus, Santacruz (E), Mumbai-400 098 (India); Fulekar, M.H., E-mail: mhfulekar@yahoo.com [Environmental Biotechnology Laboratory, Department of Life Sciences, University of Mumbai, Vidyanagari Campus, Santacruz (E), Mumbai-400 098 (India)

    2010-03-15

    Bioremediation of benzene has been carried out using cow dung microflora in a bioreactor. The bioremediation of benzene under the influence of cow dung microflora was found to be 100% and 67.5%, at initial concentrations of 100 mg/l and 250 mg/l within 72 h and 168 h respectively; where as at higher concentration (500 mg/l), benzene was found to be inhibitory. Hence the two phase partitioning bioreactor (TPPB) has been designed and developed to carryout biodegradation at higher concentration. In TPPB 5000 mg/l benzene was biodegraded up to 50.17% over a period of 168 h. Further the Pseudomonas putida MHF 7109 was isolated from cow dung microflora as potential benzene degrader and its ability to degrade benzene at various concentrations was evaluated. The data indicates 100%, 81% and 65% degradation at the concentrations of 50 mg/l, 100 mg/l, 250 mg/l within the time period of 24 h, 96 h and 168 h respectively. The GC-MS data also shows the presence of catechol and 2-hydroxymuconic semialdehyde, which confirms the established pathway of benzene biodegradation. The present research proves the potential of cow dung microflora as a source of biomass for benzene biodegradation in TPPB.

  1. 11. USING BIOMARKERS TO IMPROVE BENZENE RISK ASSESSMENT AND FIND THE CAUSES OF LEUKAEMIA

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@Benzene is an established cause of leukemia at high doses, but the risk it poses at exposures of ≤1ppm in air is diffcult to quantify. Molecular biomarkers may improve the accuracy of this risk assessment. We have therefore attempted to develop and validate biomarkers of exposure, early effect and susceptibility to benzene. We have shown

  2. Hydrogenation of Benzene over Mo2C/Al2O3 Catalyst

    Institute of Scientific and Technical Information of China (English)

    Zhang Jing; Wu Weicheng

    2008-01-01

    The process of benzene hydrogenation over Mo2C catalyst has been studied.Mo2C was the active phase in benzene hydrogenation.The major problem with the metal carbides was their poor stability due to deactivation by carbon deposition.

  3. Differential susceptibility of rats and guinea pigs to the ototoxic effects of ethyl benzene

    NARCIS (Netherlands)

    Cappaert, NLM; Klis, SFL; Muijser, H; Kulig, BM; Ravensberg, LC; Smoorenburg, GF

    2002-01-01

    The present study was designed to compare the ototoxic effects of volatile ethyl benzene in guinea pigs and rats. Rats showed deteriorated auditory thresholds in the mid-frequency range, based on electrocochleography, after 550-ppm ethyl benzene (8 h/day, 5 days). Outer hair cell (OHC) loss was foun

  4. Accurate computations of the structures and binding energies of the imidazole⋯benzene and pyrrole⋯benzene complexes

    International Nuclear Information System (INIS)

    Highlights: • We have computed accurate binding energies of two NH⋯π hydrogen bonds. • We compare to results from dispersion-corrected density-functional theory. • A double-hybrid functional with explicit correlation has been proposed. • First results of explicitly-correlated ring-coupled-cluster theory are presented. • A double-hybrid functional with random-phase approximation is investigated. - Abstract: Using explicitly-correlated coupled-cluster theory with single and double excitations, the intermolecular distances and interaction energies of the T-shaped imidazole⋯benzene and pyrrole⋯benzene complexes have been computed in a large augmented correlation-consistent quadruple-zeta basis set, adding also corrections for connected triple excitations and remaining basis-set-superposition errors. The results of these computations are used to assess other methods such as Møller–Plesset perturbation theory (MP2), spin-component-scaled MP2 theory, dispersion-weighted MP2 theory, interference-corrected explicitly-correlated MP2 theory, dispersion-corrected double-hybrid density-functional theory (DFT), DFT-based symmetry-adapted perturbation theory, the random-phase approximation, explicitly-correlated ring-coupled-cluster-doubles theory, and double-hybrid DFT with a correlation energy computed in the random-phase approximation

  5. Accurate computations of the structures and binding energies of the imidazole⋯benzene and pyrrole⋯benzene complexes

    Energy Technology Data Exchange (ETDEWEB)

    Ahnen, Sandra; Hehn, Anna-Sophia [Institute of Physical Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 2, D-76131 Karlsruhe (Germany); Vogiatzis, Konstantinos D. [Institute of Physical Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 2, D-76131 Karlsruhe (Germany); Center for Functional Nanostructures, Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Straße 1a, D-76131 Karlsruhe (Germany); Trachsel, Maria A.; Leutwyler, Samuel [Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern (Switzerland); Klopper, Wim, E-mail: klopper@kit.edu [Institute of Physical Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 2, D-76131 Karlsruhe (Germany); Center for Functional Nanostructures, Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Straße 1a, D-76131 Karlsruhe (Germany)

    2014-09-30

    Highlights: • We have computed accurate binding energies of two NH⋯π hydrogen bonds. • We compare to results from dispersion-corrected density-functional theory. • A double-hybrid functional with explicit correlation has been proposed. • First results of explicitly-correlated ring-coupled-cluster theory are presented. • A double-hybrid functional with random-phase approximation is investigated. - Abstract: Using explicitly-correlated coupled-cluster theory with single and double excitations, the intermolecular distances and interaction energies of the T-shaped imidazole⋯benzene and pyrrole⋯benzene complexes have been computed in a large augmented correlation-consistent quadruple-zeta basis set, adding also corrections for connected triple excitations and remaining basis-set-superposition errors. The results of these computations are used to assess other methods such as Møller–Plesset perturbation theory (MP2), spin-component-scaled MP2 theory, dispersion-weighted MP2 theory, interference-corrected explicitly-correlated MP2 theory, dispersion-corrected double-hybrid density-functional theory (DFT), DFT-based symmetry-adapted perturbation theory, the random-phase approximation, explicitly-correlated ring-coupled-cluster-doubles theory, and double-hybrid DFT with a correlation energy computed in the random-phase approximation.

  6. A New Paradigm for Known Metabolite Identification in Metabonomics/Metabolomics: Metabolite Identification Efficiency

    Directory of Open Access Journals (Sweden)

    Jeremy R. Everett

    2015-01-01

    Full Text Available A new paradigm is proposed for assessing confidence in the identification of known metabolites in metabonomics studies using NMR spectroscopy approaches. This new paradigm is based upon the analysis of the amount of metabolite identification information retrieved from NMR spectra relative to the molecular size of the metabolite. Several new indices are proposed including: metabolite identification efficiency (MIE and metabolite identification carbon efficiency (MICE, both of which can be easily calculated. These indices, together with some guidelines, can be used to provide a better indication of known metabolite identification confidence in metabonomics studies than existing methods. Since known metabolite identification in untargeted metabonomics studies is one of the key bottlenecks facing the science currently, it is hoped that these concepts based on molecular spectroscopic informatics, will find utility in the field.

  7. Marine environmental protection: An application of the nanometer photo catalyst method on decomposition of benzene.

    Science.gov (United States)

    Lin, Mu-Chien; Kao, Jui-Chung

    2016-04-15

    Bioremediation is currently extensively employed in the elimination of coastal oil pollution, but it is not very effective as the process takes several months to degrade oil. Among the components of oil, benzene degradation is difficult due to its stable characteristics. This paper describes an experimental study on the decomposition of benzene by titanium dioxide (TiO2) nanometer photocatalysis. The photocatalyst is illuminated with 360-nm ultraviolet light for generation of peroxide ions. This results in complete decomposition of benzene, thus yielding CO2 and H2O. In this study, a nonwoven fabric is coated with the photocatalyst and benzene. Using the Double-Shot Py-GC system on the residual component, complete decomposition of the benzene was verified by 4h of exposure to ultraviolet light. The method proposed in this study can be directly applied to elimination of marine oil pollution. Further studies will be conducted on coastal oil pollution in situ. PMID:26922359

  8. Benzaldehyde in cherry flavour as a precursor of benzene formation in beverages.

    Science.gov (United States)

    Loch, Christine; Reusch, Helmut; Ruge, Ingrid; Godelmann, Rolf; Pflaum, Tabea; Kuballa, Thomas; Schumacher, Sandra; Lachenmeier, Dirk W

    2016-09-01

    During sampling and analysis of alcohol-free beverages for food control purposes, a comparably high contamination of benzene (up to 4.6μg/L) has been detected in cherry-flavoured products, even when they were not preserved using benzoic acid (which is a known precursor of benzene formation). There has been some speculation in the literature that formation may occur from benzaldehyde, which is contained in natural and artificial cherry flavours. In this study, model experiments were able to confirm that benzaldehyde does indeed degrade to benzene under heating conditions, and especially in the presence of ascorbic acid. Analysis of a large collective of authentic beverages from the market (n=170) further confirmed that benzene content is significantly correlated to the presence of benzaldehyde (r=0.61, pcherry flavoured beverages, industrial best practices should include monitoring for benzene. Formulations containing either benzoic acid or benzaldehyde in combination with ascorbic acid should be avoided. PMID:27041300

  9. Hydrogen Storage in Benzene Moiety Decorated Single-Walled Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    ZHANG Bing-Yun; LIANG Qi-Min; SONG Chen; XIA Yue-Yuan; ZHAO Ming-wen; LIU Xiang-Dong; ZHANG Hong-Yu

    2006-01-01

    The hydrogen storage capacity of(5,5)single-walled carbon nanotubes(SWNTs)decorated chemically with benzene moieties is studied by using molecular dynamics simulations(MDSs)and density functional theory(DFT) calculations.It is found that benzene molecules colliding on (5,5) SWNTs at incident energy of 50 eV form very stable configurations of benzene moiety adsorption on the wall of SWNTs.The MDSs indicate that when the benzene moiety decorated(5,5)SWNTs and a pristine(5,5)SWNT are put in a box in which hydrogen molecules are filled to a pressure of~26 atm,the hydrogen storage capacity of the benzene moiety decorated(5,5)SWNT is about 4.7wt.% and that of the pristine (5,5) SwNT is nearly 3.9 wt.%.

  10. The Simultaneous Electrochemical Detection of Catechol and Hydroquinone with [Cu(Sal-β-Ala(3,5-DMPz2]/SWCNTs/GCE

    Directory of Open Access Journals (Sweden)

    Lina Abdullah Alshahrani

    2014-11-01

    Full Text Available A glassy carbon electrode was modified with a copper(II complex [Cu(Sal-β-Ala (3,5-DMPz2] (Sal = salicylaldehyde, β-Ala = β-alanine, 3,5-DMPz = 3,5-dimethylpyrazole and single-walled carbon nanotubes (SWCNTs. The modified electrode was used to detect catechol (CT and hydroquinone (HQ and exhibited good electrocatalytic activities toward the oxidation of CT and HQ. The peak currents were linear with the CT and HQ concentrations over the range of 5–215 μmol·L−1 and 5–370 μmol·L−1 with corresponding detection limits of 3.5 μmol·L−1 and 1.46 μmol·L−1 (S/N = 3 respectively. Moreover, the modified electrode exhibited good sensitivity, stability and reproducibility for the determination of CT and HQ, indicating the promising applications of the modified electrode in real sample analysis.

  11. Characterization of 12-molybdophosphoric acid supported on mesoporous silica MCM-41 and its catalytic performance in the synthesis of hydroquinone diacetate

    International Nuclear Information System (INIS)

    12-molybdophosphoric acid (PMA) was supported on mesoporous molecular sieves MCM-41 by impregnation of 12-molybdophosphoric acid followed by calcination. The nanochannels of MCM-41 provide a large surface area for the solid state dispersion of 12-molybdophosphoric acid. The samples have been characterized by N2 adsorption–desorption at −196 °C, transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and FT-IR measurements. The acidity and catalytic activity have been, respectively, examined by nonaqueous titration of n-butylamine in acetonitrile and synthesis of hydroquinone diacetate. The results showed that ordered hexagonal pore structure was observed in the synthesized MCM-41. Also the results indicate that PMA are highly dispersed on mesoporous silica MCM-41 spherical nanoparticles while PMA retains its Keggin structure. On the other hand, with increasing the introduced PMA amount, the specific surface area decreases, and the mesoporous ordering of the samples become poor. Both the surface acidity and the catalytic activity sharply increase with the modification of MCM-41 by PMA but decrease by increasing the calcination temperature. The sample with 55 wt% PMA/MCM-41 calcined at 350 °C shows the highest acidity and catalytic activity.

  12. Characterization of 12-molybdophosphoric acid supported on mesoporous silica MCM-41 and its catalytic performance in the synthesis of hydroquinone diacetate

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Awad I., E-mail: awahmed@mans.edu.eg [Chemistry Department, Faculty of Science, Mansoura University, Mansoura (Egypt); Samra, S.E.; El-Hakam, S.A. [Chemistry Department, Faculty of Science, Mansoura University, Mansoura (Egypt); Khder, A.S. [Faculty of Applied Science, Umm Al Qura University, Makkah (Saudi Arabia); El-Shenawy, H.Z.; El-Yazeed, W.S. Abo [Chemistry Department, Faculty of Science, Mansoura University, Mansoura (Egypt)

    2013-10-01

    12-molybdophosphoric acid (PMA) was supported on mesoporous molecular sieves MCM-41 by impregnation of 12-molybdophosphoric acid followed by calcination. The nanochannels of MCM-41 provide a large surface area for the solid state dispersion of 12-molybdophosphoric acid. The samples have been characterized by N{sub 2} adsorption–desorption at −196 °C, transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and FT-IR measurements. The acidity and catalytic activity have been, respectively, examined by nonaqueous titration of n-butylamine in acetonitrile and synthesis of hydroquinone diacetate. The results showed that ordered hexagonal pore structure was observed in the synthesized MCM-41. Also the results indicate that PMA are highly dispersed on mesoporous silica MCM-41 spherical nanoparticles while PMA retains its Keggin structure. On the other hand, with increasing the introduced PMA amount, the specific surface area decreases, and the mesoporous ordering of the samples become poor. Both the surface acidity and the catalytic activity sharply increase with the modification of MCM-41 by PMA but decrease by increasing the calcination temperature. The sample with 55 wt% PMA/MCM-41 calcined at 350 °C shows the highest acidity and catalytic activity.

  13. Characterization of 12-molybdophosphoric acid supported on mesoporous silica MCM-41 and its catalytic performance in the synthesis of hydroquinone diacetate

    Science.gov (United States)

    Ahmed, Awad I.; Samra, S. E.; El-Hakam, S. A.; Khder, A. S.; El-Shenawy, H. Z.; El-Yazeed, W. S. Abo

    2013-10-01

    12-molybdophosphoric acid (PMA) was supported on mesoporous molecular sieves MCM-41 by impregnation of 12-molybdophosphoric acid followed by calcination. The nanochannels of MCM-41 provide a large surface area for the solid state dispersion of 12-molybdophosphoric acid. The samples have been characterized by N2 adsorption-desorption at -196 °C, transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and FT-IR measurements. The acidity and catalytic activity have been, respectively, examined by nonaqueous titration of n-butylamine in acetonitrile and synthesis of hydroquinone diacetate. The results showed that ordered hexagonal pore structure was observed in the synthesized MCM-41. Also the results indicate that PMA are highly dispersed on mesoporous silica MCM-41 spherical nanoparticles while PMA retains its Keggin structure. On the other hand, with increasing the introduced PMA amount, the specific surface area decreases, and the mesoporous ordering of the samples become poor. Both the surface acidity and the catalytic activity sharply increase with the modification of MCM-41 by PMA but decrease by increasing the calcination temperature. The sample with 55 wt% PMA/MCM-41 calcined at 350 °C shows the highest acidity and catalytic activity.

  14. Simultaneous determination of hydroquinone and catechol using a glassy carbon electrode modified with gold nanoparticles, ZnS/NiS-ZnS quantum dots and L-cysteine

    International Nuclear Information System (INIS)

    We describe an electrochemical sensor for simultaneous determination of hydroquinone (HQ) and catechol (CC). A glassy carbon electrode (GCE) was modified with gold nanoparticles, L-cysteine, and ZnS/NiS-ZnS quantum dots using a layer-by-layer technique. The materials were characterized by X-ray diffractometry, field emission scanning electron microscopy, and electrochemical impedance and Fourier transform infrared spectroscopy. Cyclic voltammetry and differential pulse voltammetry revealed this modified GCE to represent a highly sensitive sensor for the simultaneous determination of HQ and CC. The anodic peak current for HQ at a working voltage of 80 mV (vs. Ag/AgCl) is related to its concentration in the 0.1 to 300 μM range (even in the presence of 0.1 mM of CC). The anodic peak current for CC at a working voltage of 184 mV is related to its concentration in the 0.5 to 400 μM range (even in the presence of 0.1 mM of HQ). The detection limits (at an S/N ratio of 3) are 24 and 71 nM for HQ and CC, respectively. The modified GCE was successfully applied to the determination of HQ and CC in aqueous solutions and gave satisfactory results. (author)

  15. Microchip-electrochemistry route for rapid screening of hydroquinone and arbutin from miscellaneous samples: Investigation of the robustness of a simple cross-injector system

    Energy Technology Data Exchange (ETDEWEB)

    Crevillen, Agustin G. [Dpto. Quimica Analitica e Ingenieria Quimica, Universidad de Alcala, 28871 Alcala de Henares, Madrid (Spain); Barrigas, Ines [Dpto. Quimica Analitica e Ingenieria Quimica, Universidad de Alcala, 28871 Alcala de Henares, Madrid (Spain); Blasco, Antonio Javier [Dpto. Quimica Analitica e Ingenieria Quimica, Universidad de Alcala, 28871 Alcala de Henares, Madrid (Spain); Gonzalez, Maria Cristina [Dpto. Quimica Analitica e Ingenieria Quimica, Universidad de Alcala, 28871 Alcala de Henares, Madrid (Spain); Escarpa, Alberto [Dpto. Quimica Analitica e Ingenieria Quimica, Universidad de Alcala, 28871 Alcala de Henares, Madrid (Spain)]. E-mail: alberto.escarpa@uah.es

    2006-03-15

    This work examines in deep the analytical performance of an example of 'first-generation' microdevices: capillary electrophoresis microchip (CE) with end-channel electrochemical detection (ED). A hydroquinone and arbutin separation strategically chosen as route involving pharmaceutical-clinical testing, public safety and food control scenes was carried out. The reproducibility of the unpinched electrokinetic protocol was carefully studied and the technical possibility of working indiscriminately and/or sequentially with both simple cross-injectors was also demonstrated using a real sample (R.S.D.'s less than 7%). The robustness of the injection protocol allowed checking the state of the microchip/detector coupling and following the extraction efficiency of the analyte from real sample. Separation variables such as pH, ionic strength and, separation voltage were also carefully assayed and optimized. Analyte screening was performed using borate buffer (pH 9, 60 mM) in less than 180 s in the samples studied improving dramatically the analysis times used for the same analytes on a conventional scale (15 min), with good precision (R.S.D.'s ranging 5-10%), accuracy (recoveries ranging 90-110%) and acceptable resolution (Rs {>=} 1.0). In addition, the excellent analytical performance of the overall analytical method indicated the quality of the whole analytical microsystem and allowed to introduce the definition of robustness for methodologies developed into the 'lab-on-a-chip' scene.

  16. Microchip-electrochemistry route for rapid screening of hydroquinone and arbutin from miscellaneous samples: Investigation of the robustness of a simple cross-injector system

    International Nuclear Information System (INIS)

    This work examines in deep the analytical performance of an example of 'first-generation' microdevices: capillary electrophoresis microchip (CE) with end-channel electrochemical detection (ED). A hydroquinone and arbutin separation strategically chosen as route involving pharmaceutical-clinical testing, public safety and food control scenes was carried out. The reproducibility of the unpinched electrokinetic protocol was carefully studied and the technical possibility of working indiscriminately and/or sequentially with both simple cross-injectors was also demonstrated using a real sample (R.S.D.'s less than 7%). The robustness of the injection protocol allowed checking the state of the microchip/detector coupling and following the extraction efficiency of the analyte from real sample. Separation variables such as pH, ionic strength and, separation voltage were also carefully assayed and optimized. Analyte screening was performed using borate buffer (pH 9, 60 mM) in less than 180 s in the samples studied improving dramatically the analysis times used for the same analytes on a conventional scale (15 min), with good precision (R.S.D.'s ranging 5-10%), accuracy (recoveries ranging 90-110%) and acceptable resolution (Rs ≥ 1.0). In addition, the excellent analytical performance of the overall analytical method indicated the quality of the whole analytical microsystem and allowed to introduce the definition of robustness for methodologies developed into the 'lab-on-a-chip' scene

  17. (Liquid + liquid) equilibria for benzene + cyclohexane + N,N-dimethylformamide + sodium thiocyanate

    International Nuclear Information System (INIS)

    Graphical abstract: On the left, the figure was phase diagram about the LLE date. On the right, the figure was about the effects of mass fraction of benzene in the raffinate phase to the selectivity(S) coefficient under different salt concentration. ■, the NaSCN and DMF in ratio of 5/95; • , the NaSCN and DMF in ratio of 10/90; ▴, the NaSCN and DMF in ratio of 15/85; ★, the NaSCN and DMF in ratio of 20/80; ▾, the NaSCN and DMF in ratio of 23/77. ♦, only DMF was used extractant (the selectivity coefficient was calculated by literature 17). w22, refer to the mass fraction of benzene in the raffinate phase (cyclohexane-rich phase). Highlights: • (Liquid + liquid) equilibrium for quaternary system was measured. • The components include benzene, cyclohexane, N,N-dimethylformamide, sodium thiocyanate. • The (liquid + liquid) equilibrium data can be well correlated by the NRTL model. • Separation of benzene and cyclohexane by NaSCN + DMF was discussed. -- Abstract: (Liquid + liquid) equilibrium (LLE) data for benzene + cyclohexane + N,N-dimethylformamide (DMF) + sodium thiocyanate (NaSCN) were measured experimentally at atmospheric pressure and 303.15 K. The selectivity coefficients from these LLE data were calculated and compared to those previously reported in the literature for the systems (benzene + cyclohexane + DMF) and (benzene + cyclohexane + DMF + KSCN). The NRTL equation was used to correlate the experimental data. The agreement between the predicted and experimental results was good. It was found that the selectivity coefficients of DMF + NaSCN for benzene ranged from 2.45 to 11.99. Considering the relatively high extraction capacity and selectivity for benzene, DMF + NaSCN may be used as a potential extracting solvent for the separation of benzene from cyclohexane

  18. Small scale spatial gradients of outdoor and indoor benzene in proximity of an integrated steel plant.

    Science.gov (United States)

    Licen, Sabina; Tolloi, Arianna; Briguglio, Sara; Piazzalunga, Andrea; Adami, Gianpiero; Barbieri, Pierluigi

    2016-05-15

    Benzene is known as a human carcinogen, whose annual mean concentration exceeded the EU limit value (5 μg/m(3)) only in very few locations in Europe during 2012. Nevertheless 10% to 12% of the EU-28 urban population was still exposed to benzene concentrations above the WHO reference level of 1.7 μg/m(3). WHO recommended a wise choice of monitoring stations positioning in proximity of "hot spots" to define and assess the representativeness of each site paying attention to micro-scale conditions. In this context benzene and other VOCs of health concern (toluene, ethylbenzene, xylenes) concentrations have been investigated, with weekly passive sampling for one year, both in outdoor and indoor air in inhabited buildings in close proximity (180 m far up to 1100 m) of an integrated steel plant in NE of Italy. Even though the outdoor mean annual benzene concentration was below the EU limit in every site, in the site closest to the works the benzene concentration was above 5 μg/m(3) in 14 weeks. These events were related to a benzene over toluene ratio above one, which is diagnostic for the presence of an industrial source, and to meteorological factors. These information pointed at the identification of the coke ovens of the plant as the dominant outdoor source of benzene. Benzene gradients with the increasing distance from coke ovens have been found for both outdoor and indoor air. Linear models linking outdoor to indoor benzene concentrations have been then identified, allowing to estimate indoor exposure from ambient air benzene data. In the considered period, a narrow area of about 250 m appeared impacted at a higher degree than the other sites both considering outdoor and indoor air. Passive BTEX sampling permits to collect information on both ambient air and daily life settings, allowing to assemble a valuable data support for further environmental cost-benefit analyses. PMID:26930323

  19. Progress of epidemiological and molecular epidemiological studies on benzene in China.

    Science.gov (United States)

    Li, Guilan; Yin, Songnian

    2006-09-01

    Benzene is an organic solvent that has been used in industry for about 100 years throughout the world. Since 1973, a series of toxicological and molecular epidemiological studies on benzene were conducted by researchers at the Chinese Academy of Preventive Medicine (CAPM) (1973-1986) and subsequently by a collaboration between the CAPM and the National Cancer Institute (NCI) in the United States that began in 1986, which was joined by investigators from the University of California at Berkeley, the University of North Carolina at Chapel Hill, and New York University. The findings demonstrated that the risk of leukemia and lymphoma among benzene-exposed workers was significantly increased, with elevated risks for leukemia present not only at higher exposure but also among workers exposed to under 10 ppm. Therefore, the benzene permissible level was decreased to 1.8 ppm (6 mg/m(3)) and benzene-induced leukemia is treated as an occupational cancer in China. The benzene permissible level is 1.0 in the United States and in several other developed countries and it has been suggested to be decreased to 0.5 ppm (ACGIH). A number of potential biomarkers are related to benzene exposure and poisoning. Some of these are benzene oxide-protein adducts, chromosome aberration of lymphocytes, and GPA mutations in erythrocytes, a decrease in B cell and CD4(-)T cell counts in peripheral blood, and altered expression of CXCL16, ZNF331, JUN, and PF4 in lymphocytes. Variation in multiple benzene metabolizing genes may be associated with risk of benzene hematotoxicity, including CYP2E1, MPO, NQO1, and GSTT1. PMID:17119257

  20. Effect Of Polar Component(1-Propanol On The RelativeVolatility Of The Binary System N-Hexane - Benzene

    Directory of Open Access Journals (Sweden)

    Khalid Farhod Chasib Al-Jiboury

    2008-01-01

    Full Text Available Vapor-liquid equilibrium data are presented for the binary systems n-hexane - 1-propanol, benzene - 1-propanol and n-hexane – benzene at 760 mm of mercury pressure. In addition ternary data are presented at selected compositions with respect to the 1-propanol in the 1-propanol, benzene, n-hexane system at 760 mmHg. The results indicate the relative volatility of n-hexane relative to benzene increases appreciably with addition of 1-propanol

  1. In situ FTIR Investigation of Magnetic Field Effect on Heterogeneous Photocatalytic Degradation of Benzene over Pt/TiO2

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    In situ FTIR spectroscopy was utlized to investigate the magnetic field effect on the heterogeneous photocatalytic degradation of benzene over platinized titania (Pt/TiO2). The results revealed that the employment of magnetic field may not change the mechanism of photocatalytic degradation of benzene, however, it greatly facilitate the conversion of benzene to phenol and quinone, as well as the transformation from phenol to quinone, resulting in opening the benzene ring easily and promoting the production of CO2.

  2. Removal of the hazardous, volatile, and organic compound benzene from aqueous solution using phosphoric acid activated carbon from rice husk

    OpenAIRE

    Yakout, Sobhy M

    2014-01-01

    Background Benzene is one of the most hazardous organic pollutants in groundwater. The removal of benzene from water is very important from a health point of view and for environmental protection. In this study, benzene adsorption kinetics was investigated using phosphoric acid activated carbon, prepared from rice husk. Results An initial rapid uptake of benzene was observed and became almost constant after 40 minutes of contact. Kinetic data was analyzed using pseudo first order, pseudo seco...

  3. Application of mass spectrometry for metabolite identification.

    Science.gov (United States)

    Ma, Shuguang; Chowdhury, Swapan K; Alton, Kevin B

    2006-06-01

    Metabolism studies play a pivotal role in drug discovery and development. Characterization of metabolic "hot-spots" as well as reactive and pharmacologically active metabolites is critical to designing new drug candidates with improved metabolic stability, toxicological profile and efficacy. Metabolite identification in the preclinical species used for safety evaluation is required in order to determine whether human metabolites have been adequately tested during non-clinical safety assessment. From an instrumental standpoint, high performance liquid chromatography (HPLC) coupled with mass spectrometry (MS) dominates all analytical tools used for metabolite identification. The general strategies employed for metabolite identification in both drug discovery and drug development settings together with sample preparation techniques are reviewed herein. These include a discussion of the various ionization methods, mass analyzers, and tandem mass spectrometry (MS/MS) techniques that are used for structural characterization in a modern drug metabolism laboratory. Mass spectrometry-based techniques, such as stable isotope labeling, on-line H/D exchange, accurate mass measurement to enhance metabolite identification and recent improvements in data acquisition and processing for accelerating metabolite identification are also described. Rounding out this review, we offer additional thoughts about the potential of alternative and less frequently used techniques such as LC-NMR/MS, CRIMS and ICPMS. PMID:16787159

  4. 40 CFR 721.10072 - Benzene, 1,1′-methylenebis[4-isocyanato-, polymer with benzenedicarboxylic acid, butyl dialkyl...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Benzene, 1,1â²-methylenebis , .alpha... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10072 Benzene, 1,1′-methylenebis... to reporting. (1) The chemical substance identified generically as benzene,...

  5. 40 CFR 721.2535 - Benzene, 1,1′-methylanebis[4-isocyanato-, homopolymer, Bu alc.-blocked.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Benzene, 1,1â²-methylanebis[4... Significant New Uses for Specific Chemical Substances § 721.2535 Benzene, 1,1′-methylanebis[4-isocyanato... chemical substance identified as benzene, 1,1′-methylanebis[4-isocyanato-, homopolymer, Bu...

  6. 40 CFR 80.1352 - What are the pre-compliance reporting requirements for the gasoline benzene program?

    Science.gov (United States)

    2010-07-01

    ... requirements for the gasoline benzene program? 80.1352 Section 80.1352 Protection of Environment ENVIRONMENTAL... Benzene Recordkeeping and Reporting Requirements § 80.1352 What are the pre-compliance reporting requirements for the gasoline benzene program? (a) Except as provided in paragraph (c) of this section,...

  7. Pre-commissioning of 120 kt/a Unit for Hydrotreating Crude Coke Oven Benzene Implemented at Baoyuan Chemical Company

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ The Baoyuan Chemical Company, Ltd. in Taiyuan has per-formed the precommissioning of a 120 kt/a unit for hydrotreating crude coke oven benzene. This unit is the phase II construction of the 300 kt/a crude benzene hydrotreating project, which adopts the process technology for hydrotreating crude coke oven benzene developed indepen-dently by our own efforts.

  8. 40 CFR 721.984 - Amino-hydroxy sulfonaphthylazo-disubstituted phenyl azo benzene carboxylate salt (generic).

    Science.gov (United States)

    2010-07-01

    ...-disubstituted phenyl azo benzene carboxylate salt (generic). 721.984 Section 721.984 Protection of Environment...-disubstituted phenyl azo benzene carboxylate salt (generic). (a) Chemical substance and significant new uses...-disubstituted phenyl azo benzene carboxylate salt (PMN P-00-0351) is subject to reporting under this section...

  9. Nonthermal plasma assisted photocatalytic oxidation of dilute benzene

    Indian Academy of Sciences (India)

    J Karuppiah; E Linga Reddy; L Sivachandiran; R Karvembu; Ch Subrahmanyam

    2012-07-01

    Oxidative decomposition of low concentrations (50-1000 ppm) of diluted benzene in air was carried out in a nonthermal plasma (NTP) dielectric barrier discharge (DBD) reactor with the inner electrode made up of stainless steel fibres (SMF) modified with transition metal oxides in such a way to integrate the catalyst in discharge zone. Typical results indicate the better performance of MnO and TiO2/MnO modified systems, which may be attributed to the in situ decomposition of ozone on the surface of MnO that may lead to the formation of atomic oxygen; whereas ultraviolet light induced photocatalytic oxidation may be taking place with TiO2 modified systems. Water vapour improved the selectivity to total oxidation.

  10. Adsorption of benzene, cyclohexane and hexane on ordered mesoporous carbon.

    Science.gov (United States)

    Wang, Gang; Dou, Baojuan; Zhang, Zhongshen; Wang, Junhui; Liu, Haier; Hao, Zhengping

    2015-04-01

    Ordered mesoporous carbon (OMC) with high specific surface area and large pore volume was synthesized and tested for use as an adsorbent for volatile organic compound (VOC) disposal. Benzene, cyclohexane and hexane were selected as typical adsorbates due to their different molecular sizes and extensive utilization in industrial processes. In spite of their structural differences, high adsorption amounts were achieved for all three adsorbates, as the pore size of OMC is large enough for the access of these VOCs. In addition, the unusual bimodal-like pore size distribution gives the adsorbates a higher diffusion rate compared with conventional adsorbents such as activated carbon and carbon molecular sieve. Kinetic analysis suggests that the adsorption barriers mainly originated from the difficulty of VOC vapor molecules entering the pore channels of adsorbents. Therefore, its superior adsorption ability toward VOCs, together with a high diffusion rate, makes the ordered mesoporous carbon a promising potential adsorbent for VOC disposal. PMID:25872710

  11. Nonlinear response of the benzene molecule to strong magnetic fields

    Science.gov (United States)

    Pagola, G. I.; Caputo, M. C.; Ferraro, M. B.; Lazzeretti, P.

    2005-02-01

    The fourth-rank hypermagnetizability tensor of the benzene molecule has been evaluated at the coupled Hartree-Fock level of accuracy within the conventional common-origin approach, adopting gaugeless basis sets of increasing size and flexibility. The degree of convergence of theoretical tensor components has been estimated allowing for two different coordinate systems. It is shown that a strong magnetic field perpendicular to the plane of the molecule causes a distortion of the electron charge density, which tends to concentrate in the region of the C-C bonds. This charge contraction has a dynamical origin, and can be interpreted as a feedback effect in terms of the classical Lorentz force acting on the electron current density.

  12. Modeling Biodegradation Kinetics on Benzene and Toluene and Their Mixture

    Directory of Open Access Journals (Sweden)

    Aparecido N. Módenes

    2007-10-01

    Full Text Available The objective of this work was to model the biodegradation kinetics of toxic compounds toluene and benzene as pure substrates and in a mixture. As a control, Monod and Andrews models were used. To predict substrates interactions, more sophisticated models of inhibition and competition, and SKIP (sum kinetics interactions parameters model were applied. The models evaluation was performed based on the experimental data from Pseudomonas putida F1 activities published in the literature. In parameter identification procedure, the global method of particle swarm optimization (PSO was applied. The simulation results show that the better description of the biodegradation process of pure toxic substrate can be achieved by Andrews' model. The biodegradation process of a mixture of toxic substrates is modeled the best when modified competitive inhibition and SKIP models are used. The developed software can be used as a toolbox of a kinetics model catalogue of industrial wastewater treatment for process design and optimization.

  13. Benzene ring chains with lithium adsorption: Vibrations and their implications

    CERN Document Server

    Stegmann, Thomas; Seligman, Thomas H

    2016-01-01

    Lithium adsorption on aromatic molecules and polyacenes have been found to produce strong distortions associated to spontaneous symmetry breaking and lesser ones in more general cases. For polyphenyls we find similar, but more varied behaviour; an important feature is the fact that adsorption largely suppresses the torsion present in naked polyphenyl. The spectra of the vibrational modes distinguish the different structures of skeletons and adsorbates. In the more regular adsorption schemes the lowest states are bending and torsion modes of the skeleton, which are essential followed by the adsorbate. Based on this we propose the possible use of such a chain of adsorbates on a chain of benzene rings as a quantum register with the lowest vibrations transmitting qubits for control gates. To strengthen this view and to show the effect of heavier alkalines we also present the very symmetric adsorption of ten rubidium atoms on pentaphenyl.

  14. Solvent isotope effect on viscosity of polystyrene-benzene solutions

    International Nuclear Information System (INIS)

    The concentration and temperature dependencies of viscosity and density of solutions of nearly monodisperse samples (Mw/Mn w) ranging from 4x103 to 4x105 between 293-313 K. Isotope H/D substitution in benzene causes visible changes in viscosity and density of solutions, however, its influence on intrinsic viscosities and Huggins constants, derived from the concentration dependences of viscosity, is negligible. No isotope effects on the exponents in the power low relationship have been detected. The viscosities of the solutions have been also correlated with the densities. The apparent close-packed volumes are practically constant for all solutions and seem to be determined by the properties of the solvent. The deuterium substitution visibly affects the close-packed volumes - they decrease by approximately 13%, both in pure solvent and in solutions. (author)

  15. Radiolysis of Aqueous Benzene Solutions at higher temperatures

    International Nuclear Information System (INIS)

    Aqueous solutions of benzene have been irradiated with Co γ-rays with doses of up to 2.3 Mrad in the temperature region 100 - 200 C. At 100 C a linear relationship between the phenol concentration and the absorbed dose was obtained, but at 150 C and at higher temperatures the rate of the phenol formation increased significantly after an initial constant period. With higher doses the rate decreased again, falling almost to zero at 200 C after a dose of 2.2 Mrad. The G value of phenol in the initial linear period increased from 2.8 at 100 C to 8.0 at 200 C. The reaction mechanism is discussed and reactions constituting a chain reaction are suggested. The result of the addition of iron ions and of a few inorganic oxides to the system is presented and briefly discussed

  16. Separation of Scintillation and Cherenkov Lights in Linear Alkyl Benzene

    CERN Document Server

    Li, Mohan; Yeh, Minfang; Wang, Zhe; Chen, Shaomin

    2015-01-01

    To separate scintillation and Cherenkov lights in water-based liquid scintillator detectors is a desired feature for future neutrino and proton decay researches. Linear alkyl benzene (LAB) is one important ingredient of a water-based liquid scintillator being developed. In this paper we observed a good separation of scintillation and Cherenkov lights in an LAB sample. The rising and decay times of the scintillation light of the LAB were measured to be $(7.7\\pm3.0)\\ \\rm{ns}$ and $(36.6\\pm2.4)\\ \\rm{ns}$, respectively, while the full width [-3$\\sigma$, 3$\\sigma$] of the Cherenkov light was 12 ns dominated by the time resolution of our photomultiplier tubes. The light yield of the scintillation was measured to be $(1.01\\pm0.12)\\times10^3\\ \\rm{photons}/\\rm{MeV}$.

  17. A wood preservative metabolite in river water.

    Science.gov (United States)

    Khoroshko, Larisa O; Petrova, Varvara N; Viktorovskii, Igor V; Lahtiperä, Mirja; Sinkkonen, Seija; Paasivirta, Jaakko

    2005-01-01

    A previously unknown pollutant in river water was identified to be 2-mercaptobenzothiazole (2-MBT) by interpretation and simulation of its GC/LRMS spectrum. Further GC/HRMS measurement of the isotope composition of the molecular ion verified this structure. 2-MBT is a well-known agent for corrosion inhibition and a stable metabolite of several other benzothiazoles. The present 2-MBT trace was most probably a metabolite of the wood preservative TCMTB which leaked from an upstream sawmill. The metabolite had been detected earlier in urine of the sawmill workers, but now was identified in the recipient water environment for the first time. PMID:15768735

  18. Secondary Metabolites from Rubiaceae Species

    Directory of Open Access Journals (Sweden)

    Daiane Martins

    2015-07-01

    Full Text Available This study describes some characteristics of the Rubiaceae family pertaining to the occurrence and distribution of secondary metabolites in the main genera of this family. It reports the review of phytochemical studies addressing all species of Rubiaceae, published between 1990 and 2014. Iridoids, anthraquinones, triterpenes, indole alkaloids as well as other varying alkaloid subclasses, have shown to be the most common. These compounds have been mostly isolated from the genera Uncaria, Psychotria, Hedyotis, Ophiorrhiza and Morinda. The occurrence and distribution of iridoids, alkaloids and anthraquinones point out their chemotaxonomic correlation among tribes and subfamilies. From an evolutionary point of view, Rubioideae is the most ancient subfamily, followed by Ixoroideae and finally Cinchonoideae. The chemical biosynthetic pathway, which is not so specific in Rubioideae, can explain this and large amounts of both iridoids and indole alkaloids are produced. In Ixoroideae, the most active biosysthetic pathway is the one that produces iridoids; while in Cinchonoideae, it produces indole alkaloids together with other alkaloids. The chemical biosynthetic pathway now supports this botanical conclusion.

  19. Secondary metabolites from Rubiaceae species.

    Science.gov (United States)

    Martins, Daiane; Nunez, Cecilia Veronica

    2015-01-01

    This study describes some characteristics of the Rubiaceae family pertaining to the occurrence and distribution of secondary metabolites in the main genera of this family. It reports the review of phytochemical studies addressing all species of Rubiaceae, published between 1990 and 2014. Iridoids, anthraquinones, triterpenes, indole alkaloids as well as other varying alkaloid subclasses, have shown to be the most common. These compounds have been mostly isolated from the genera Uncaria, Psychotria, Hedyotis, Ophiorrhiza and Morinda. The occurrence and distribution of iridoids, alkaloids and anthraquinones point out their chemotaxonomic correlation among tribes and subfamilies. From an evolutionary point of view, Rubioideae is the most ancient subfamily, followed by Ixoroideae and finally Cinchonoideae. The chemical biosynthetic pathway, which is not so specific in Rubioideae, can explain this and large amounts of both iridoids and indole alkaloids are produced. In Ixoroideae, the most active biosysthetic pathway is the one that produces iridoids; while in Cinchonoideae, it produces indole alkaloids together with other alkaloids. The chemical biosynthetic pathway now supports this botanical conclusion. PMID:26205062

  20. The use of microporous divinyl benzene copolymer for yeast cell immobilization and ethanol production in packed-bed reactor.

    Science.gov (United States)

    Karagöz, Pinar; Erhan, Elif; Keskinler, Bülent; Ozkan, Melek

    2009-01-01

    Microporous divinyl benzene copolymer (MDBP) was used for the first time as immobilization material for Saccharomyces cerevisiae ATCC 26602 cells in a bed reactor and ethanol production from glucose was studied as a model system. A very homogenous thick layer of yeast cells were seen from the scanning electron micrographs on the outer walls of biopolymer. The dried weight of the cells was found to be approximately 2 g per gram of cell supporting material. Hydrophobic nature of polymer is an important factor increasing cell adhesion on polymer pieces. The dynamic flow conditions through the biomaterial due to its microporous architecture prevented exopolysaccharide matrix formation around cells and continuous washing out of toxic metabolites and dead and degraded cells from the reactor provided less diffusional limitations and dynamic living environment to the cells. In order to see the ethanol production performance of immobilized yeast cells, a large initial concentration range of glucose between 6.7 and 300 g/l was studied at 1 ml/min in continuous packed-bed reactor. The inhibition effect of glucose with increasing initial concentration was observed at above 150 g/l, a relatively high substrate concentration. The continuous fluid flow around the microenvironment of the attached cells and mass transferring ability of cell immobilized on MDBP can help in decreasing the inhibition effect of ethanol accumulation and high substrate concentration in the vicinity of the cells. PMID:18712507

  1. Hydrogeologic characterization and assessment of bioremediation of chlorinated benzenes and benzene in wetland areas, Standard Chlorine of Delaware, Inc. Superfund Site, New Castle County, Delaware, 2009-12

    Science.gov (United States)

    Lorah, Michelle M.; Walker, Charles W.; Baker, Anna C.; Teunis, Jessica A.; Majcher, Emily H.; Brayton, Michael J.; Raffensperger, Jeff P.; Cozzarelli, Isabelle M.

    2014-01-01

    Wetlands at the Standard Chlorine of Delaware, Inc. Superfund Site (SCD) in New Castle County, Delaware, are affected by contamination with chlorobenzenes and benzene from past waste storage and disposal, spills, leaks, and contaminated groundwater discharge. In cooperation with the U.S. Environmental Protection Agency, the U.S. Geological Survey began an investigation in June 2009 to characterize the hydrogeology and geochemistry in the wetlands and assess the feasibility of monitored natural attenuation and enhanced bioremediation as remedial strategies. Groundwater flow in the wetland study area is predominantly vertically upward in the wetland sediments and the underlying aquifer, and groundwater discharge accounts for a minimum of 47 percent of the total discharge for the subwatershed of tidal Red Lion Creek. Thus, groundwater transport of contaminants to surface water could be significant. The major contaminants detected in groundwater in the wetland study area included benzene, monochlorobenzene, and tri- and di-chlorobenzenes. Shallow wetland groundwater in the northwest part of the wetland study area was characterized by high concentrations of total chlorinated benzenes and benzene (maximum about 75,000 micrograms per liter [μg/L]), low pH, and high chloride. In the northeast part of the wetland study area, wetland groundwater had low to moderate concentrations of total chlorinated benzenes and benzene (generally not greater than 10,000 μg/L), moderate pH, and high sulfate concentrations. Concentrations in the groundwater in excess of 1 percent of the solubility of the individual chlorinated benzenes indicate that a contaminant source is present in the wetland sediments as dense nonaqueous phase liquids (DNAPLs). Consistently higher contaminant concentrations in the shallow wetland groundwater than deeper in the wetland sediments or the aquifer also indicate a continued source in the wetland sediments, which could include dissolution of DNAPLs and

  2. Electrochemical degradation of benzene in natural water using silver nanoparticle-decorated carbon nanotubes

    International Nuclear Information System (INIS)

    In this study, a novel methodology for the electrochemical degradation of benzene in natural water using silver nanoparticle-decorated carbon nanotubes has been investigated. The morphology, the structure, and the electrochemical performance of the multi-walled carbon nanotubes-silver (MWCNT-Ag) nanocomposite film were characterised by transmission electron microscopy (TEM), X-ray diffraction (XRD), and cyclic voltammetry (CV), respectively. Electrocatalytic oxidation of benzene in an aqueous solution was studied to evaluate potential applications of the MWCNT-Ag modified glassy carbon (GC) electrode in environmental science. The benzene removal efficiency in natural water containing 10 mg L−1 benzene yielded 77.9% at an applied potential of +2.0 V for 2 h using the MWCNT-Ag-GC electrode. In comparison, the removal efficiency reached only 8.0% with the bare GC electrode, showing the suitability of the MWCNT-Ag nanocomposite modified GC electrode for electro-oxidation of benzene in natural water. - Graphical abstract: Display Omitted - Highlights: • A novel methodology for the electrochemical degradation of benzene was developed. • Sensor based on silver nanoparticle-decorated carbon nanotubes was used. • The proposed method is suitable and efficient for the removal of benzene

  3. Biodegradation of high concentrations of benzene vapors in a two phase partition stirred tank bioreactor

    Directory of Open Access Journals (Sweden)

    Karimi Ali

    2013-01-01

    Full Text Available Abstract The present study examined the biodegradation rate of benzene vapors in a two phase stirred tank bioreactor by a bacterial consortium obtained from wastewater of an oil industry refinery house. Initially, the ability of the microbial consortium for degrading benzene was evaluated before running the bioreactor. The gaseous samples from inlet and outlet of bioreactor were directly injected into a gas chromatograph to determine benzene concentrations. Carbone oxide concentration at the inlet and outlet of bioreactor were also measured with a CO2 meter to determine the mineralization rate of benzene. Influence of the second non-aqueous phase (silicon oil has been emphasized, so at the first stage the removal efficiency (RE and elimination capacity (EC of benzene vapors were evaluated without any organic phase and in the second stage, 10% of silicon oil was added to bioreactor media as an organic phase. Addition of silicon oil increased the biodegradation performance up to an inlet loading of 5580 mg/m3, a condition at which, the elimination capacity and removal efficiency were 181 g/m3/h and 95% respectively. The elimination rate of benzene increased by 38% in the presence of 10% of silicone oil. The finding of this study demonstrated that two phase partition bioreactors (TPPBs are potentially effective tools for the treatment of gas streams contaminated with high concentrations of poorly water soluble organic contaminant, such as benzene.

  4. Study of Humidity Effect on Benzene Decomposition by the Dielectric Barrier Discharge Nonthermal Plasma Reactor

    Science.gov (United States)

    Ma, Tianpeng; Zhao, Qiong; Liu, Jianqi; Zhong, Fangchuan

    2016-06-01

    The humidity effects on the benzene decomposition process were investigated by the dielectric barrier discharge (DBD) plasma reactor. The results showed that the water vapor played an important role in the benzene oxidation process. It was found that there was an optimum humidity value for the benzene removal efficiency, and at around 60% relative humidity (RH), the optimum benzene removal efficiency was achieved. At a SIE of 378 J/L, the removal efficiency was 66% at 0% RH, while the removal efficiency reached 75.3% at 60% RH and dropped to 69% at 80% RH. Furthermore, the addition of water inhibited the formation of ozone and NO2 remarkably. Both of the concentrations of ozone and NO2 decreased with increasing of the RH at the same specific input energy. At a SIE of 256 J/L, the concentrations of ozone and NO2 were 5.4 mg/L and 1791 ppm under dry conditions, whereas they were only 3.4 mg/L and 1119 ppm at 63.5% RH, respectively. Finally, the outlet gas after benzene degradation was qualitatively analyzed by FT-IR and GC-MS to determine possible intermediate byproducts. The results suggested that the byproducts in decomposition of benzene primarily consisted of phenol and substitutions of phenol. Based on these byproducts a benzene degradation mechanism was proposed. supported by National Natural Science Foundation of China (Nos. 11205007 and 11205029)

  5. Modulation of phase-II enzyme activities in benzene treated ovariectomized rats.

    Science.gov (United States)

    Verma, Yeshvandra; Rana, S V S

    2011-05-01

    The aim of the study was to determine the influence of ovariectomy on phase II enzymes viz. glutathione-S-transferase (GST), glutathione peroxidase (GPX) and catalase (CAT) in liver and kidney of female rats treated with benzene. The results showed the significant decrease of the GST and GPX activity in benzene treated rats after ovariectomy. However progesterone supplementation stimulated the activity of GST and GPX in liver and kidney of benzene treated non ovariectomized and ovariectomized rats. Progesterone supplementation to benzene treated ovariectomized rats helps to gain in CAT activity. Our results on DNA damage using single cell gel electrophoresis also confirmed our findings on antioxidant enzymes. The results showed that lack of protective progesterone against benzene toxicity is reflected in alterations in antioxidant enzyme activities. However progesterone therapy to benzene treated ovariectomized rats results in activating the antioxidant defence system. Since female workers are engaged in industrial sector, these results are important from occupational health point of view. Benzene exposure affects their reproductive health. Nevertheless, it could be modulated by suitable hormonal therapy. PMID:21787707

  6. Benzene derivatives adsorbed to the Ag(111) surface: Binding sites and electronic structure

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Daniel P.; Tymińska, Nina; Zurek, Eva, E-mail: ezurek@buffalo.edu [Department of Chemistry, State University of New York at Buffalo, Buffalo, New York 14260-3000 (United States); Simpson, Scott [Department of Chemistry, State University of New York at Buffalo, Buffalo, New York 14260-3000 (United States); School of Science, Penn State Erie, The Behrend College, 4205 College Drive, Erie, Pennsylvania 16563 (United States)

    2015-03-14

    Dispersion corrected Density Functional Theory calculations were employed to study the adsorption of benzenes derivatized with functional groups encompassing a large region of the activated/deactivated spectrum to the Ag(111) surface. Benzenes substituted with weak activating or deactivating groups, such as methyl and fluoro, do not have a strong preference for adsorbing to a particular site on the substrate, with the corrugations in the potential energy surface being similar to those of benzene. Strong activating (N(CH{sub 3}){sub 2}) and deactivating (NO{sub 2}) groups, on the other hand, possess a distinct site preference. The nitrogen in the former prefers to lie above a silver atom (top site), but in the latter a hollow hexagonal-closed-packed (H{sub hcp}) site of the Ag(111) surface is favored instead. Benzenes derivatized with classic activating groups donate electron density from their highest occupied molecular orbital to the surface, and those functionalized with deactivating groups withdraw electron density from the surface into orbitals that are unoccupied in the gas phase. For benzenes functionalized with two substituents, the groups that are strongly activating or deactivating control the site preference and the other groups assume sites that are, to a large degree, dictated by their positions on the benzene ring. The relative stabilities of the ortho, meta, and para positional isomers of disubstituted benzenes can, in some cases, be modified by adsorption to the surface.

  7. Electrochemical degradation of benzene in natural water using silver nanoparticle-decorated carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Cesarino, Ivana, E-mail: ivana@iqsc.usp.br [Instituto de Química de São Carlos, Universidade de São Paulo, C.P. 780, 13560-970, São Carlos, SP (Brazil); Cesarino, Vivian; Moraes, Fernando C.; Ferreira, Tanare C.R.; Lanza, Marcos R.V. [Instituto de Química de São Carlos, Universidade de São Paulo, C.P. 780, 13560-970, São Carlos, SP (Brazil); Mascaro, Lucia H. [Departamento de Química, Universidade Federal de São Carlos, C.P. 676, 13560-970, São Carlos, SP (Brazil); Machado, Sergio A.S. [Instituto de Química de São Carlos, Universidade de São Paulo, C.P. 780, 13560-970, São Carlos, SP (Brazil)

    2013-08-15

    In this study, a novel methodology for the electrochemical degradation of benzene in natural water using silver nanoparticle-decorated carbon nanotubes has been investigated. The morphology, the structure, and the electrochemical performance of the multi-walled carbon nanotubes-silver (MWCNT-Ag) nanocomposite film were characterised by transmission electron microscopy (TEM), X-ray diffraction (XRD), and cyclic voltammetry (CV), respectively. Electrocatalytic oxidation of benzene in an aqueous solution was studied to evaluate potential applications of the MWCNT-Ag modified glassy carbon (GC) electrode in environmental science. The benzene removal efficiency in natural water containing 10 mg L{sup −1} benzene yielded 77.9% at an applied potential of +2.0 V for 2 h using the MWCNT-Ag-GC electrode. In comparison, the removal efficiency reached only 8.0% with the bare GC electrode, showing the suitability of the MWCNT-Ag nanocomposite modified GC electrode for electro-oxidation of benzene in natural water. - Graphical abstract: Display Omitted - Highlights: • A novel methodology for the electrochemical degradation of benzene was developed. • Sensor based on silver nanoparticle-decorated carbon nanotubes was used. • The proposed method is suitable and efficient for the removal of benzene.

  8. Benzene derivatives adsorbed to the Ag(111) surface: Binding sites and electronic structure

    International Nuclear Information System (INIS)

    Dispersion corrected Density Functional Theory calculations were employed to study the adsorption of benzenes derivatized with functional groups encompassing a large region of the activated/deactivated spectrum to the Ag(111) surface. Benzenes substituted with weak activating or deactivating groups, such as methyl and fluoro, do not have a strong preference for adsorbing to a particular site on the substrate, with the corrugations in the potential energy surface being similar to those of benzene. Strong activating (N(CH3)2) and deactivating (NO2) groups, on the other hand, possess a distinct site preference. The nitrogen in the former prefers to lie above a silver atom (top site), but in the latter a hollow hexagonal-closed-packed (Hhcp) site of the Ag(111) surface is favored instead. Benzenes derivatized with classic activating groups donate electron density from their highest occupied molecular orbital to the surface, and those functionalized with deactivating groups withdraw electron density from the surface into orbitals that are unoccupied in the gas phase. For benzenes functionalized with two substituents, the groups that are strongly activating or deactivating control the site preference and the other groups assume sites that are, to a large degree, dictated by their positions on the benzene ring. The relative stabilities of the ortho, meta, and para positional isomers of disubstituted benzenes can, in some cases, be modified by adsorption to the surface

  9. The role of C-H$\\ldots$ interaction in the stabilization of benzene and adamantane clusters

    Indian Academy of Sciences (India)

    R Mahesh Kumar; M Elango; R Parthasarathi; Dolly Vijay; V Subramanian

    2012-01-01

    In this investigation, a systematic attempt has been made to understand the interaction between adamantane and benzene using both ab initio and density functional theory methods. C-H$\\ldots$ type of interaction between C-H groups of adamantane and cloud of benzene is found as the important attraction for complex formation. The study also reveals that the methylene (-CH2) and methine (-CH) groups of adamantane interact with benzene resulting in different geometrical structures. And it is found that the former complex is stronger than the later. The diamondoid structure of adamantane enables it to interact with a maximum of four benzene molecules, each one along the four faces. The stability of the complex increases with increase in the number of benzene molecules. The energy decomposition analysis of adamantane-benzene complexes using DMA approach shows that the origin of the stability primarily arises from the dispersive interaction. The theory of atoms in molecules (AIM) supports the existence of weak interaction between the two systems. The electrostatic topography features provide clues for the mode of interaction of adamantane with benzene.

  10. Biodegradation of High Concentrations of Benzene Vapors in a Two Phase Partition Stirred Tank Bioreactor

    Directory of Open Access Journals (Sweden)

    Ali Karimi

    2013-01-01

    Full Text Available The present study examined the biodegradation rate of benzene vapors in a two phase stirred tank bioreactor by a bacterial consortium obtained from wastewater of an oil industry refinery house. Initially, the ability of the microbial consortium for degrading benzene was evaluated before running the bioreactor. The gaseous samples from inlet and outlet of bioreactor were directly injected into a gas chromatograph to determine benzene concentrations. Carbone oxide concentration at the inlet and outlet of bioreactor were also measured with a CO2 meter to determine the mineralization rate of benzene. Influence of the second non-aqueous phase (silicon oil has been emphasized, so at the first stage the removal efficiency (RE and elimination capacity (EC of benzene vapors were evaluated without any organic phase and in the second stage, 10% of silicon oil was added to bioreactor media as an organic phase. Addition of silicon oil increased the biodegradation performance up to an inlet loading of 5580?mg/m3, a condition at which, the elimination capacity and removal efficiency were 181?g/m3/h and 95% respectively. The elimination rate of benzene increased by 38% in the presence of 10% of silicone oil. The finding of this study demonstrated that two phase partition bioreactors (TPPBs are potentially effective tools for the treatment of gas streams contaminated with high concentrations of poorly water soluble organic contaminant, such as benzene.

  11. Retrospective benzene exposure assessment for a multi-center case-cohort study of benzene-exposed workers in China.

    Science.gov (United States)

    Portengen, Lützen; Linet, Martha S; Li, Gui-Lan; Lan, Qing; Dores, Graça M; Ji, Bu-Tian; Hayes, Richard B; Yin, Song-Nian; Rothman, Nathaniel; Vermeulen, Roel

    2016-05-01

    Quality of exposure assessment has been shown to be related to the ability to detect risk of lymphohematopoietic disorders in epidemiological investigations of benzene, especially at low levels of exposure. We set out to build a statistical model for reconstructing exposure levels for 2898 subjects from 501 factories that were part of a nested case-cohort study within the NCI-CAPM cohort of more than 110,000 workers. We used a hierarchical model to allow for clustering of measurements by factory, workshop, job, and date. To calibrate the model we used historical routine monitoring data. Measurements below the limit of detection were accommodated by constructing a censored data likelihood. Potential non-linear and industry-specific time-trends and predictor effects were incorporated using regression splines and random effects. A partial validation of predicted exposures in 2004/2005 was performed through comparison with full-shift measurements from an exposure survey in facilities that were still open. Median cumulative exposure to benzene at age 50 for subjects that ever held an exposed job (n=1175) was 509 mg/m(3) years. Direct comparison of model estimates with measured full-shift personal exposure in the 2004/2005 survey showed moderate correlation and a potential downward bias at low (<1 mg/m(3)) exposure estimates. The modeling framework enabled us to deal with the data complexities generally found in studies using historical exposure data in a comprehensive way and we therefore expect to be able to investigate effects at relatively low exposure levels. PMID:26264985

  12. Metabolite profiles of common Stemphylium species

    DEFF Research Database (Denmark)

    Andersen, Birgitte; Solfrizzo, Michelle; Visconti, Angelo

    1995-01-01

    identified by their chromatographic and spectroscopic data (Rf values, reflectance spectrum, retention index and ultraviolet spectrum). These metabolites have been used for the chemotaxonomical characterization of Stemphylium botryosum, S. herbarum, S. alfalfae, S. majusculum, S. sarciniforme, S. vesicarium...

  13. Secondary metabolites of slime molds (myxomycetes)

    Czech Academy of Sciences Publication Activity Database

    Dembitsky, V. M.; Řezanka, Tomáš; Spížek, Jaroslav; Hanuš, L. O.

    2005-01-01

    Roč. 66, - (2005), s. 747-769. ISSN 0031-9422 Institutional research plan: CEZ:AV0Z50200510 Keywords : slime molds * myxomycetes * metabolites Subject RIV: EE - Microbiology, Virology Impact factor: 2.780, year: 2005

  14. Benzene dispersion and natural attenuation in an alluvial aquifer with strong interactions with surface water

    Science.gov (United States)

    Batlle-Aguilar, Jordi; Brouyère, Serge; Dassargues, Alain; Morasch, Barbara; Hunkeler, Daniel; Höhener, Patrick; Diels, Ludo; Vanbroekhoven, Karolien; Seuntjens, Piet; Halen, Henri

    2009-05-01

    SummaryField and laboratory investigations have been conducted at a former coke plant, in order to assess pollutant attenuation in a contaminated alluvial aquifer, discharging to an adjacent river. Various organic (BTEX, PAHs, mineral oils) and inorganic (As, Zn, Cd) compounds were found in the aquifer in concentrations exceeding regulatory values. Due to redox conditions of the aquifer, heavy metals were almost immobile, thus not posing a major risk of dispersion off-site the brownfield. Field and laboratory investigations demonstrated that benzene, among organic pollutants, presented the major worry for off-site dispersion, mainly due to its mobility and high concentration, i.e. up to 750 mg L -1 in the source zone. However, benzene could never be detected near the river which is about 160 m downgradient the main source. Redox conditions together with benzene concentrations determined in the aquifer have suggested that degradation mainly occurred within 100 m distance from the contaminant source under anoxic conditions, and most probably with sulphate as main oxidant. A numerical groundwater flow and transport model, calibrated under transient conditions, was used to simulate benzene attenuation in the alluvial aquifer towards the Meuse River. The mean benzene degradation rate used in the model was quantified in situ along the groundwater flow path using compound-specific carbon isotope analysis (CSIA). The results of the solute transport simulations confirmed that benzene concentrations decreased almost five orders of magnitude 70 m downgradient the source. Simulated concentrations have been found to be below the detection limit in the zone adjacent to the river and consistent with the absence of benzene in downgradient piezometers located close to the river reported in groundwater sampling campaigns. In a transient model scenario including groundwater-surface water dynamics, benzene concentrations were observed to be inversely correlated to the river water

  15. Effect of benzene on the cerebellar structure and behavioral characteristics in rats

    Institute of Scientific and Technical Information of China (English)

    Ali; Rafati; Mahboobeh; Erfanizadeh; Ali; Noorafshan; Saied; Karbalay-Doust

    2015-01-01

    Objective: To investigate the effects of benzene on rat’s cerebellum structure and behavioral characteristics, including anxiety and motor impairment.Methods: Twenty rats were randomly allocated into two groups orally receiving distilled water and benzene(200 mg/kg/day). A total of 10 rats were used at the beginning of benzene exposure. Two rats died during benzene treatment and 8 rats remained for evaluation of the behavioral test and finally 6 rats underwent histological assessment. At the end of the 4th week, motor function and anxiety were evaluated in rotarod test and elevated plus maze, respectively. Besides, the cerebellum was dissected for structural assessment using stereological methods.Results: Performance of the benzene-treated rats in fixed and accelerating speed rotarod was impaired and their riding time(endurance) was lower compared to the control group(P = 0.02). The benzene-treated rats also spent less time in the open arms and had fewer entrances to the open arms in comparison to the control group, indicating anxiety(P = 0.01). The total volume of the cerebellar hemisphere, its cortex, intracerebellar nuclei, total number of the Purkinje, Bergmann, Golgi, granule, neurons and glial cells of the molecular layer, and neurons and glial cells of the intracerebellar nuclei were reduced by 34%-76% in the benzene-treated rats in comparison to the distilled water group(P = 0.003). The most cell loss was seen in Bergmann glia. Conclusions: The structure of cerebellum altered after benzene treatment. In addition, motor impairment and anxiety could be seen in benzene-treated rats.

  16. Effect of benzene on the cerebellar structure and behavioral characteristics in rats

    Institute of Scientific and Technical Information of China (English)

    Ali Rafati; Mahboobeh Erfanizadeh; Ali Noorafshan; Saied Karbalay-Doust

    2015-01-01

    Objective:To investigate the effects of benzene on rat’s cerebellum structure and behavioral characteristics, including anxiety and motor impairment. Methods:Twenty rats were randomly allocated into two groups orally receiving distilled water and benzene (200 mg/kg/day). A total of 10 rats were used at the beginning of benzene exposure. Two rats died during benzene treatment and 8 rats remained for evaluation of the behavioral test and finally 6 rats underwent histological assessment. At the end of the 4th week, motor function and anxiety were evaluated in rotarod test and elevated plus maze, respectively. Besides, the cerebellum was dissected for structural assessment using stereological methods. Results:Performance of the benzene-treated rats in fixed and accelerating speed rotarod was impaired and their riding time (endurance) was lower compared to the control group (P=0.02). The benzene-treated rats also spent less time in the open arms and had fewer entrances to the open arms in comparison to the control group, indicating anxiety (P=0.01). The total volume of the cerebellar hemisphere, its cortex, intracerebellar nuclei, total number of the Purkinje, Bergmann, Golgi, granule, neurons and glial cells of the molecular layer, and neurons and glial cells of the intracerebellar nuclei were reduced by 34%-76%in the benzene-treated rats in comparison to the distilled water group (P=0.003). The most cell loss was seen in Bergmann glia. Conclusions:The structure of cerebellum altered after benzene treatment. In addition, motor impairment and anxiety could be seen in benzene-treated rats.

  17. Metabolism and metabolites of polychlorinated biphenyls (PCBs)

    OpenAIRE

    Grimm, FA; Hu, D.; Kania-Korwel, I.; Lehmler, HJ; Ludewig, G; Hornbuckle, KC; Duffel, MW; Bergman, A; Robertson, LW

    2015-01-01

    The metabolism of polychlorinated biphenyls (PCBs) is complex and has an impact on toxicity and thereby assessment of PCB risks. A large number of reactive and stable metabolites are formed in the processes of biotransformation in biota in general and in humans in particular. The aim of this document is to provide an overview of PCB metabolism and to identify metabolites of concern and their occurrence. Emphasis is given to mammalian metabolism of PCBs and their hydroxyl, methylsulfonyl, and ...

  18. Biologically active secondary metabolites from marine cyanobacteria

    OpenAIRE

    Nunnery, Joshawna K.; Mevers, Emily; Gerwick, William H

    2010-01-01

    Marine cyanobacteria are a rich source of complex bioactive secondary metabolites which derive from mixed biosynthetic pathways. Recently, several marine cyanobacterial natural products have garnered much attention due to their intriguing structures and exciting anti-proliferative or cancer cell toxic activities. Several other recently discovered secondary metabolites exhibit insightful neurotoxic activities whereas others are showing pronounced anti-inflammatory activity. A number of anti-in...

  19. Low-molecular-weight metabolite systems chemistry

    OpenAIRE

    Hadacek, Franz; Bachmann, Gert

    2015-01-01

    Low-molecular-weight metabolites (LMWMs) comprise primary or central and a plethora of intermediary or secondary metabolites, all of which are characterized by a molecular weight below 900 Dalton. The latter are especially prominent in sessile higher organisms, such as plants, corals, sponges and fungi, but are produced by all types of microbial organisms too. Common to all of these carbon molecules are oxygen, nitrogen and, to a lesser extent, sulfur, as heteroatoms. The latter can contribut...

  20. Analytical strategies for identifying drug metabolites.

    Science.gov (United States)

    Prakash, Chandra; Shaffer, Christopher L; Nedderman, Angus

    2007-01-01

    With the dramatic increase in the number of new chemical entities (NCEs) arising from combinatorial chemistry and modern high-throughput bioassays, novel bioanalytical techniques are required for the rapid determination of the metabolic stability and metabolites of these NCEs. Knowledge of the metabolic site(s) of the NCEs in early drug discovery is essential for selecting compounds with favorable pharmacokinetic credentials and aiding medicinal chemists in modifying metabolic "soft spots". In development, elucidation of biotransformation pathways of a drug candidate by identifying its circulatory and excretory metabolites is vitally important to understand its physiological effects. Mass spectrometry (MS) and nuclear magnetic resonance (NMR) have played an invaluable role in the structural characterization and quantification of drug metabolites. Indeed, liquid chromatography (LC) coupled with atmospheric pressure ionization (API) MS has now become the most powerful tool for the rapid detection, structure elucidation, and quantification of drug-derived material within various biological fluids. Often, however, MS alone is insufficient to identify the exact position of oxidation, to differentiate isomers, or to provide the precise structure of unusual and/or unstable metabolites. In addition, an excess of endogenous material in biological samples often suppress the ionization of drug-related material complicating metabolite identification by MS. In these cases, multiple analytical and wet chemistry techniques, such as LC-NMR, enzymatic hydrolysis, chemical derivatization, and hydrogen/deuterium-exchange (H/D-exchange) combined with MS are used to characterize the novel and isomeric metabolites of drug candidates. This review describes sample preparation and introduction strategies to minimize ion suppression by biological matrices for metabolite identification studies, the application of various LC-tandem MS (LC-MS/MS) techniques for the rapid quantification and

  1. Synthesis of the major metabolites of Tolvaptan

    Institute of Scientific and Technical Information of China (English)

    Wei Li Wan; Jian Bo Wu; Fan Lei; Xiao Long Li; Li Hai; Yong Wu

    2012-01-01

    Tolvaptan is a nonpeptide arginine vasopressin (AVP) V2-receptor antagonist and used in the treatment of heart failure,cirrhosis,syndrome of inappropriate antidiuretic hormone secretion or other high-volume capacity of hyponatremia.The metabolites of tolvaptan are mainly produced by CYP3A4,including two major compounds named DM-4103 and DM-4107.Herein,the chemical synthesis of those two metabolites is described in this article for further study.

  2. Bond Energy Sums in Benzene, Cyclohexatriene and Cyclohexane Prove Resonance Unnecessary

    CERN Document Server

    Heyrovska, Raji

    2008-01-01

    The recent new structure of benzene shows that it consists of three C atoms of radii as in graphite alternating with three C atoms with double bond radii. This is different from the hypothetical cyclohexatriene (Kekule structure) involving alternate double and single bonds. It was shown that the difference in the bond energy sum of the atomic structure of benzene from that of the Kekule structure is the energy (erroneously) assumed to be due to resonance. Here it is shown that the present structure of benzene also explains the energy of hydrogenation into cyclohexane and its difference from that of cyclohexatriene.

  3. Survey of Recycled Nano Magnetic Particle in Benzene Removal from Aqueous Solution

    OpenAIRE

    Amin M.M.; Bina B.; Samani Majd A.M.; Pourzamani H.

    2013-01-01

    The removal of benzene, a hazardous monoaromatic compound, from aqueous solution by recycled nano magnetic particle (NM) Fe3O4 in batch condition was evaluated. Regeneration studies verified that the benzene adsorbed by the NM could be easily desorbed by temperature. So that the benzene removal effi-ciency was 98.7% for raw NM, 97.8% for first recycled NM and 97.4 percent for second recycled NM. It is expected that the Fe3O4 nanoparticles with fine grain size (20-30 nm) will be used as one of...

  4. Spin Polarization Inversion at Benzene-Absorbed Fe4N Surface

    KAUST Repository

    Zhang, Qian

    2015-05-27

    We report a first-principle study on electronic structure and simulation of the spin-polarized scanning tunneling microscopy graphic of a benzene/Fe4N interface. Fe4N is a compound ferromagnet suitable for many spintronic applications. We found that, depending on the particular termination schemes and interface configurations, the spin polarization on the benzene surface shows a rich variety of properties ranging from cosine-type oscillation to polarization inversion. Spin-polarization inversion above benzene is resulting from the hybridizations between C pz and the out-of-plane d orbitals of Fe atom.

  5. Study on the application of reduced graphene oxide and multiwall carbon nanotubes hybrid materials for simultaneous determination of catechol, hydroquinone, p-cresol and nitrite

    International Nuclear Information System (INIS)

    Graphical abstract: In this paper, the reduced graphene oxide and multiwall carbon nanotubes hybrid materials (RGO–MWNTs) were prepared and a novel strategy for the simultaneous determination of multiple environmental contaminations has been proposed on the basis of RGO–MWNTs hybrid materials modified electrode. The hybrid materials were characterized by the scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and N2 sorption–desorption isotherms. Due to the excellent catalytic activity, enhanced electrical conductivity, high surface area and porous structure of the RGO–MWNTs, the RGO–MWNTs/GCE achieved the simultaneous measurement of hydroquinone (HQ), catechol (CC), p-cresol (PC) and nitrite (NO2−) with well-separate four peaks. Scheme 1a illuminated the preparation process of the RGO–MWNTs hybrid materials. Scheme 1b explains the electron mediating properties of RGO–MWNTs/GCE towards the oxidation of HQ, CC, PC and NO2−. Scheme 1c presented the SEM image of RGO–MWNTs hybrid materials. Scheme 1d and e showed the 2D and 3D AFM images of RGO–MWNTs films, respectively. Highlights: ► The novel RGO–MWNTs hybrid materials were synthesized. ► The simultaneous detection of four environmental contaminations was achieved. ► SEM, AFM, XPS was employed to characterize the RGO–MWNTs hybrid materials. - Abstract: In this paper, the reduced graphene oxide and multiwall carbon nanotubes hybrid materials (RGO–MWNTs) were prepared and a strategy for detecting environmental contaminations was proposed on the basis of RGO–MWNTs modified electrode. The hybrid materials were characterized by the scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and N2 sorption–desorption isotherms. Due to the excellent catalytic activity, enhanced electrical conductivity and high surface area of the RGO–MWNTs, the simultaneous measurement of hydroquinone

  6. Study on the application of reduced graphene oxide and multiwall carbon nanotubes hybrid materials for simultaneous determination of catechol, hydroquinone, p-cresol and nitrite

    Energy Technology Data Exchange (ETDEWEB)

    Hu Fangxin [Education Ministry Key Laboratory on Luminescence and Real-Time Analysis, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Chen Shihong, E-mail: cshong@swu.edu.cn [Education Ministry Key Laboratory on Luminescence and Real-Time Analysis, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Wang Chengyan [Education Ministry Key Laboratory on Luminescence and Real-Time Analysis, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Yuan Ruo, E-mail: yuanruo@swu.edu.cn [Education Ministry Key Laboratory on Luminescence and Real-Time Analysis, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Yuan Dehua; Wang Cun [Education Ministry Key Laboratory on Luminescence and Real-Time Analysis, School of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China)

    2012-04-29

    Graphical abstract: In this paper, the reduced graphene oxide and multiwall carbon nanotubes hybrid materials (RGO-MWNTs) were prepared and a novel strategy for the simultaneous determination of multiple environmental contaminations has been proposed on the basis of RGO-MWNTs hybrid materials modified electrode. The hybrid materials were characterized by the scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and N{sub 2} sorption-desorption isotherms. Due to the excellent catalytic activity, enhanced electrical conductivity, high surface area and porous structure of the RGO-MWNTs, the RGO-MWNTs/GCE achieved the simultaneous measurement of hydroquinone (HQ), catechol (CC), p-cresol (PC) and nitrite (NO{sub 2}{sup -}) with well-separate four peaks. Scheme 1a illuminated the preparation process of the RGO-MWNTs hybrid materials. Scheme 1b explains the electron mediating properties of RGO-MWNTs/GCE towards the oxidation of HQ, CC, PC and NO{sub 2}{sup -}. Scheme 1c presented the SEM image of RGO-MWNTs hybrid materials. Scheme 1d and e showed the 2D and 3D AFM images of RGO-MWNTs films, respectively. Highlights: Black-Right-Pointing-Pointer The novel RGO-MWNTs hybrid materials were synthesized. Black-Right-Pointing-Pointer The simultaneous detection of four environmental contaminations was achieved. Black-Right-Pointing-Pointer SEM, AFM, XPS was employed to characterize the RGO-MWNTs hybrid materials. - Abstract: In this paper, the reduced graphene oxide and multiwall carbon nanotubes hybrid materials (RGO-MWNTs) were prepared and a strategy for detecting environmental contaminations was proposed on the basis of RGO-MWNTs modified electrode. The hybrid materials were characterized by the scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and N{sub 2} sorption-desorption isotherms. Due to the excellent catalytic activity, enhanced electrical conductivity and high

  7. A comparison of benzene, toluene and C{sub 2}-benzenes mixing ratios in automotive exhaust and in the suburban atmosphere during the introduction of catalytic converter technology to the Swiss Car Fleet

    Energy Technology Data Exchange (ETDEWEB)

    Heeb, N.V.; Forss, A.-M.; Bach, C.; Reimann, S.; Herzog, A.; Jackle, H.W. [Swiss Federal Laboratories for Materials Testing and Research, Duebendorf (Switzerland)

    2000-07-01

    Time-resolved chemical ionization mass spectrometry (CIMS) has been used to investigate the variations of the mixing ratios of benzene, toluene and the C{sub 2}-benzenes (xylenes and ethyl benzene) in automotive exhaust during transient engine operation. A significant increase of the benzene/toluene ratios from 0.35 to 1.31 (median) was found upon introduction of a catalytic converter system. A preliminary emission model was developed from these test stand measurements to simulate benzene/toluene ratios of passenger car fleets with variable proportions of three-way catalyst vehicles. Although only the emissions of gasoline-driven passenger cars have been considered so far, the predicted increase of the benzene/toluene ratios during the introduction period of the three-way catalyst from 1980 to 2000 is in good agreement with the observed increase of the atmospheric benzene/toluene ratio measured at a suburban monitoring site (Dubendorf, Switzerland) which is strongly influenced by road traffic emissions. At this site, the atmospheric concentrations of benzene and alkyl benzenes have been detected at hourly intervals since 1993. A steady decrease of the yearly mean from 3.54 to 2.00 ppb for toluene and from 2.87 to 1.33 ppb for the sum of C{sub 2}-benzenes was found from 1994 to 1998, respectively, when the proportion of three-way catalyst passenger cars increased from 60 to 82%. Nevertheless, the mean benzene concentration was only affected to a small degree (from 1.10 to 0.97 ppb) within the same period of time. Thus, the observed increase of the atmospheric benzene/toluene-mixing ratios from 0.32 to 0.58 (mean) is in good agreement with the predicted values from the presented emission model. Reduced catalyst conversion efficiency for benzene with respect to alkylated benzenes can explain most of the observed increase of the benzene/toluene and benzene/C{sub 2}-benzenes mixing rations. In addition, benzene emissions e.g. from the class of light duty vehicles, which

  8. A lack of consensus in the literature findings on the removal of airborne benzene by houseplants: Effect of bacterial enrichment

    Science.gov (United States)

    Sriprapat, Wararat; Strand, Stuart E.

    2016-04-01

    Removal rates of benzene and formaldehyde gas by houseplants reported by several laboratories varied by several orders of magnitude. We hypothesized that these variations were caused by differential responses of soil microbial populations to the high levels of pollutant used in the studies, and tested responses to benzene by plants and soils separately. Five houseplant species and tobacco were exposed to benzene under hydroponic conditions and the uptake rates compared. Among the test plants, Syngonium podophyllum and Chlorophytum comosum and Epipremnum aureum had the highest benzene removal rates. The effects of benzene addition on populations of soil bacteria were determined using reverse transcription quantitative PCR (RT-qPCR) assays targeting microbial genes involved in benzene degradation. The total bacterial population increased as shown by increases in the levels of eubacteria 16S rRNA, which was significantly higher in the high benzene incubations than in the low benzene incubations. Transcripts (mRNA) of genes encoding phenol monooxygenases, catechol-2,3-dioxygenase and the housekeeping gene rpoB increased in all soils incubated with high benzene concentrations. Therefore the enrichment of soils with benzene gas levels typical of experiments with houseplants in the literature artificially increased the levels of total soil bacterial populations, and especially the levels and activities of benzene-degrading bacteria.

  9. Photoelectrocatalytic analysis and electrocatalytic determination of hydroquinone by using a Cu2O-reduced graphene oxide nanocomposite modified rotating ring-disk electrode.

    Science.gov (United States)

    Xie, Hong; Duan, Kaiyue; Xue, Muyin; Du, Yongling; Wang, Chunming

    2016-08-01

    Reduced graphene oxide (rGO)-based Cu2O nanocomposites were prepared by a facile one-pot reaction process. The surface morphology, structure and chemical composition of Cu2O-rGO nanocomposites were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The Cu2O-rGO modified Pt rotating ring-disk electrode (RRDE) was successfully fabricated for the photoelectrocatalytic analysis of hydroquinone (HQ). The photoelectrochemical behaviors of HQ were investigated by the hydrodynamic differential pulse voltammetry technique, using the Cu2O-rGO modified Pt RRDE as the working electrode. The effects of pH values, rotation rates, illumination time and applied bias potential have been discussed. The possible electroactive intermediate product, namely hydroxyhydroquinone, was obtained through the photoelectrocatalytic degradation of HQ on the Cu2O-rGO modified Pt disk electrode, which was compulsively transported and could only be detected at the bare Pt ring electrode at around +0.02 V with an oxidation signal. We found that the peak current at +0.02 V had a good linear relationship with the HQ concentration in the range from 5.0 × 10(-6) to 1.0 × 10(-3) M, with a low limit of detection and excellent reproducibility. The present work has demonstrated that Cu2O-rGO nanocomposites have enhanced photoelectrocatalytic ability for the degradation of organic pollutants and this modified RRDE technique can be potentially applied for the in situ determination of organic pollutants. PMID:27297492

  10. Collision lifetimes of polyatomic molecules at low temperatures: Benzene–benzene vs benzene–rare gas atom collisions

    International Nuclear Information System (INIS)

    We use classical trajectory calculations to study the effects of the interaction strength and the geometry of rigid polyatomic molecules on the formation of long-lived collision complexes at low collision energies. We first compare the results of the calculations for collisions of benzene molecules with rare gas atoms He, Ne, Ar, Kr, and Xe. The comparison illustrates that the mean lifetimes of the collision complexes increase monotonically with the strength of the atom–molecule interaction. We then compare the results of the atom–benzene calculations with those for benzene–benzene collisions. The comparison illustrates that the mean lifetimes of the benzene–benzene collision complexes are significantly reduced due to non-ergodic effects prohibiting the molecules from sampling the entire configuration space. We find that the thermally averaged lifetimes of the benzene–benzene collisions are much shorter than those for Xe with benzene and similar to those for Ne with benzene

  11. CH/pi interaction between benzene and hydrocarbons having six carbon atoms in their binary liquid mixtures.

    Science.gov (United States)

    Kasahara, Yasutoshi; Suzuki, Yuji; Kabasawa, Aino; Minami, Hideyuki; Matsuzawa, Hideyo; Iwahashi, Makio

    2010-01-01

    Molecular interactions between benzene and hydrocarbons having six carbon atoms, such as hexane, cyclohexane and 1-hexene in their binary liquid mixtures were studied through the measurements of density, viscosity, self-diffusion coefficient, (13)C NMR spin-lattice relaxation time and (1)H NMR chemical shift. CH/pi attraction between hexane and benzene in their binary mixture was observed in a relatively benzene rich region, whereas a special attractive interaction was not observed between cyclohexane and benzene. On the other hand, 1-hexene and benzene in their binary mixtures were characteristic in their self-diffusion coefficient behaviors: 1-hexene more strongly attract benzene not only by the CH/pi attraction but also probably by the p/p interaction between the double bond in 1-hexene and the p-electron in benzene ring. PMID:20032596

  12. Benzene and MTBE Sorption in Fine Grain Sediments

    Science.gov (United States)

    Leal-Bautista, R. M.; Lenczewski, M. E.

    2003-12-01

    The practice of adding methyl tert-butyl ether (MTBE) to gasoline started in the late 1970s and increased dramatically in the 1990s. MTBE first was added as a substitute for tetra-ethyl lead then later as a fuel oxygenate. Although the use of MTBE has resulted in significant reduction in air pollution, it has become a significant groundwater contaminant due to its high solubility in water, high environmental mobility, and low potential for biodegradation. A recent report (1999-2001) by the Metropolitan Water District of Southern California in collaboration with United State Geological Survey and the Oregon Health and Science University found that MTBE was the second most frequent detected volatile organic compound in groundwater. In Illinois, MTBE has been found in 26 of the 1,800 public water supplies. MTBE has also been blended in Mexico into two types of gasoline sold in the country by the state oil company (PEMEX) but is not monitored in groundwater at this time. Early research on MTBE considered it unable to adsorb to soils and sediments, however, by increasing the organic matter and decreasing the size of the grains (silts or clays) this may increase sorption. The objective of this study is to determine if fine grained materials have the potential for sorption of MTBE due to its high specific surface area (10-700 m 2/g) and potentially high organic matter (0.5-3.8%). The experiment consisted of sorption isotherms to glacial tills from DeKalb, Illinois and lacustrine clays from Chalco, Mexico. Experiments were performed with various concentrations of MTBE and benzene (10, 50, 100, 500 and 1000 ug/L) at 10° C and 25° C. Results showed a range of values for the distribution coefficient (Kd, linear model). At 10° C the Kd value for MTBE was 0.187 mL/g for lacustrine clay while the glacial loess had a value of 0.009 mL/g. The highest Kd values with MTBE were 0.2859 mL/g for organic rich lacustrine clays and 0.014 mL/g for glacial loess at 25° C. The highest

  13. Production of Arbutin through Biotransformation of Exogenous Hydroquinone by Datura stramonium Cell Suspension Cultures%白花曼陀罗细胞悬浮培养生物转化外源氢醌合成熊果苷的研究

    Institute of Scientific and Technical Information of China (English)

    彭春秀; 龚加顺

    2006-01-01

    研究了白花曼陀罗细胞悬浮培养对外源氢醌的糖基化.转化细胞来自白花曼陀罗嫩茎在LS固体培养基上诱导产生的愈伤组织.白花曼陀罗悬浮培养细胞不能分泌熊果苷,但能糖基化外源氢醌合成熊果苷.当氢醌添加量达240 μmol/100mL培养物时,约有93.4%的氢醌转化形成了熊果苷,并应用多种色谱技术进行分离纯化,进行了HPLC分析和结构鉴定.%To investigate the biotransformation of hydroquinone by cell suspension cultures of Datura stramonium. Cultured cells derived from stems of Datura stramonium were maintained in Linsmaiher and Skoog (LS) solid medium. Datura stramonium cells in suspension cultures did not accumulate arbutin (4-hydroxyphenyl-β-D-glucopyranoside) but were able to specifically o-glucosylate exogenous hydroquinone at position 1. In particular, Datura cultures glucosylated ca 93.4% of hydroquinone (240 μmol/100 mL cultures) within 8 days after hydroquinone administered. The arbutin obtained was extracted from the cultures and further purified by silicon Gel column chromatography. The exogenous hydroquinone and arbutin were analyzed by HPLC.

  14. Kinetics of Liquid-Phase Hydrogenation of Benzene in a Metal Hydride Slurry System Formed by M1Ni5 and Benzene

    Institute of Scientific and Technical Information of China (English)

    代世耀; 徐国华; 安越; 陈长聘; 陈立新; 王启东

    2003-01-01

    The kinetics of liquid-phase hydrogenation of benzene in misch metal nickel-five (M1Ni5) and benzene slurry system was studied by investigating the influences of the reaction temperature, pressure, alloy concentration and stirring speed on the mass transfer-reaction processes inside the slurry. The results show that the whole process is controlled by the reaction at the surface of the catalyst. The mass transfer resistance at gas-liquid interface and that from the bulk liquid phase to the surface of the catalyst particles are negligible. The apparent reaction rate is zero order for benzene concentration and first order for hydrogen concentration in the liquid phase. The kinetic model obtained fits the experimental data very well. The apparent activation energy of the hydrogen absorption reaction of M1Ni5-C6H6 slurry system is 42.16 kJ·mo1-1.

  15. Decomposition of benzene in air streams by UV/TiO2 process

    International Nuclear Information System (INIS)

    Photocatalytic decomposition of gaseous benzene at room temperature was studied with a fixed-bed annular reactor using titania as the photocatalyst. The effects of humidity, UV light intensity and benzene concentration on the conversion and mineralization of benzene were presented. Experimental results can be adequately described by using the Langmuir-Hinshelwood (L-H) kinetic model. The concentration distribution of benzene in the annular reactors of various dimensions can be described by combining the reactor design equation with L-H kinetics. Deactivation of catalyst was observed and attributed to the adsorption of reaction intermediates on TiO2 surface. The deactivated TiO2 catalyst could be photochemically regenerated by ozone-purging in the presence of humidity

  16. Very low-energy electron scattering from benzene: experiment and theory

    International Nuclear Information System (INIS)

    Low-energy collision studies have shown that the scattering cross section for electrons by benzene rises sharply at electron impact energies below ∼200 meV. This was attributed in earlier work to electron attachment and formation of benzene anions with lifetimes τ≥1 μs. A detailed study of electron attachment to benzene is reported here that makes use of Rydberg atom techniques. The data provide no evidence for the formation of long-lived benzene anions, although a small collisional ionization signal is observed which is consistent with the formation of short-lived excited anions (τ≤3 ps). An alternative explanation for the rapid rise in cross section at low energy is presented, based on ab initio scattering calculations. These calculations indicate that virtual state scattering takes place at low energies. Possible implications of this are briefly discussed. (author)

  17. DFT study of benzene and CO co-adsorption on PtCo(1 1 1)

    International Nuclear Information System (INIS)

    Co-adsorption of benzene and CO on PtCo(1 1 1) surface at low coverage is studied using density functional theory calculations. We investigated the PtCo FCT alloy surface with a uniform distribution. The most favorable site for CO is top on a Pt atom whereas for benzene is an HCP hollow site (formed by 2 Pt atoms and 1 Co atom). The co-adsorption energy is −1.62 eV. The calculations indicate a CO molecule with a ∼4° tilt angle with the normal to the surface. The most important bond is Pt-CCO, as revealed by overlap population analysis. A very small CO–benzene interaction is also detected. The vibrational frequencies of adsorbed benzene and CO were also computed.

  18. Benzene adsorption on PtCo(1 1 1): A DFT study

    International Nuclear Information System (INIS)

    Adsorption benzene on PtCo(1 1 1) surface at low coverage is investigated using density functional theory calculations. We have investigated the PtCo FCT alloy surface with a uniform distribution and two-benzene orientation on the surface. It was found that the most favorable site is a Co-Co bridge with an adsorption energy of −0.37 eV. A large buckling for the first Co and Pt atoms on the surface layers and a 17–30° H-tilt angles are found. The bonding analysis indicates that C-C and C-H bonding increase while Pt-Pt, Co-Co and Pt-Co decrease 13.2, 73 and 33%, respectively, after adsorption benzene. The vibrational frequencies of adsorbed benzene were also calculated.

  19. Desorption of silver atoms from benzene-covered Ag(1 1 1) by energetic Ar+ bombardment

    International Nuclear Information System (INIS)

    Experiments have been conducted to gain insight into the processes of desorption of neutral species from surfaces covered with organic molecules due to bombardment with keV particles. The system is comprised of benzene molecules adsorbed onto Ag(1 1 1) and bombarded with 8 keV Ar+ ions. Molecular dynamics (MD) simulations of the same system have been performed. Results show that the presence of the benzene alters the yield, the kinetic energy distributions, and the angular distributions of the silver atoms. These changes of the desorption characteristics are the result of collisions between the Ag atoms and the benzene molecules adsorbed to the surface. As more benzene is adsorbed to the surface, the changes to the Ag atom desorption characteristics become more pronounced. The simulations reproduce the modifications to the Ag atom energy and angle distributions

  20. Biomonitoring of benzene and toluene in human blood by headspace-solid-phase microextraction

    Energy Technology Data Exchange (ETDEWEB)

    Schimming, E.; Levsen, K. [Fraunhofer-Institut fuer Toxikologie und Aerosolforschung (ITA), Hannover (Germany); Koehme, C.; Schuermann, W. [Medizinische Hochschule Hannover (Germany). Abt. fuer Pneumologie

    1999-01-01

    A simple and rapid method for the determination of benzene and toluene in whole blood by headspace-solid-phase microextraction (HS-SPME) is described. Using SPME fibres coated with 65 {mu}m carboxene/polydimethylsiloxane, limits of quantification (LOQ) of 5 ng/L for benzene and 25 ng/L for toluene are achieved. As a result of its large linear range (i.e. 5-5000 ng/L for benzene) the method is suitable for biomonitoring of both occupationally and environmentally exposed people. The reproducibility of the determination of benzene is {<=} 8%. An interlaboratory comparison demonstrated that the method proposed here compares favorably with existing methods (dynamic headspace, purge and trap). (orig.) With 2 figs., 2 tabs., 10 refs.

  1. Prevention of benzene-induced myelotoxicity by nonsteroidal anti-inflammatory drugs

    Energy Technology Data Exchange (ETDEWEB)

    Kalf, G.F.; Schlosser, M.J.; Renz, J.F.; Pirozzi, S.J. (Jefferson Medical College of Thomas Jefferson Univ., Philadelphia, PA (USA))

    1989-07-01

    Benzene affects hematopoietic progenitor cells leading to bone marrow depression and genotoxic effects such as micronucleus formation. Progenitor cell proliferation and differentiation are inhibited by prostaglandins produced by macrophages. Administration of benzene to DBA/2 or C57BL/6 mice caused a dose-dependent bone marrow depression and a significant increase in marrow prostaglandin E level and both were prevented by the coadministration of indomethacin and other inhibitors of the cyclooxygenase component of prostaglandin H synthase. Levels of benzene that decreased bone marrow cellularity also caused genotoxic effects measured as increased micronucleated polychromatic erythrocytes in peripheral blood, which was also prevented by the coadministration of indomethacin. These results suggest a possible role for prostaglandin synthase in benzene myelotoxicity; a mechanism by which this might occur is presented.

  2. Inhibition of Ps Formation in Benzene and Cyclohexane by CH3CI and CH3Br

    DEFF Research Database (Denmark)

    Wikander, G.; Mogensen, O. E.; Pedersen, Niels Jørgen

    1983-01-01

    Positron-annihilation lifetime spectra have been measured for mixtures of CH3Cl and CH3Br in cyclohexane and of CH3Cl in benzene. The ortho-positronium (Ps) yield decreased monotonically from 38% and 43% in cyclohexane and benzene respectively to 11% in pure CH3Cl and 6% in pure CH3Br. The strength...... electron from the CH3X− anions to form Ps. while it forms a bound state with the halides. X−. CH3Cl was a roughly three times weaker Ps inhibitor in benzene than in cyclohexane, which shows that CH3Cl− does not dechlorinate in times comparable to or shorter than 400–500 ps in benzene. An improved model for...

  3. Hydrogen isotope exchange between boranes and deuterated aromatic hydrocarbons: evidence for reversible hydroboration of benzene

    International Nuclear Information System (INIS)

    Pentaborane, B5H9, and diborane, B2H6, undergo hydrogen isotope exchange with deuterated aromatic hydrocarbons. Lewis acid catalyzed hydrogen isotope exchange occurs between benzene-d6 and the apical hydrogen atom of B5H9 to form 1-DB5H8 at ambient temperature. In uncatalyzed exchanges, B5H9 reacts with deuterated aromatic hydrocarbons to produce 1,2,3,4,5-D5B5H4 at +450C and B5D9 at +1200C. This thermally induced hydrogen isotope exchange apparently occurs via a reversible hydroboration of the aromatic ring. Diborane undergoes a similar isotope exchange with benzene-d6 under mild thermal conditions. 18 references, 6 figures, 3 tables

  4. Experimental research on benzene detection using ion mobility spectrometer with a laser ionization source

    Institute of Scientific and Technical Information of China (English)

    LIU Xian-yun; KONG Xiang-he; JI Ren-dong; ZHANG Shu-dong

    2006-01-01

    An ion mobility spectrometer equipped with a laser ionization source is used for the sensitive detection of benzene.Mobility spectra of the benzene are presented.We also discussed the mobility spectra at various concentrations and drift voltages.Detection limits are determined to be in the upper ppbv range.In the end,the advantages and possibilities of this technique are briefly discussed.

  5. Genotoxic and histotoxic effects of air pollutants at a benzene station on albino rats

    OpenAIRE

    Mohamed Abousalem; Amer Elgerwi; Abdel Baset El-Mashad

    2014-01-01

    Background: This study was designed to explore the hazardous effects of occupational exposure to air pollutants arising from benzene stations. Methods: A total of 48 albino rats were divided into three groups each of sixteen animals. Groups-I and II were kept at a benzene station for 60 and 120 days, respectively; while group-III was kept as a control under normal laboratory conditions. At the end of the experiment, animals were sacrificed and bone marrow samples were taken to investigate ...

  6. Biodegradation of mixtures of substituted benzenes by Pseudomonas sp. strain JS150.

    OpenAIRE

    Haigler, B E; Pettigrew, C A; Spain, J C

    1992-01-01

    Pseudomonas sp. strain JS150 was isolated as a nonencapsulated variant of Pseudomonas sp. strain JS1 that contains the genes for the degradative pathways of a wide range of substituted aromatic compounds. Pseudomonas sp. strain JS150 grew on phenol, ethylbenzene, toluene, benzene, naphthalene, benzoate, p-hydroxybenzoate, salicylate, chlorobenzene, and several 1,4-dihalogenated benzenes. We designed experiments to determine the conditions required for induction of the individual pathways and ...

  7. A system for the analysis of tritium content in natural waters, through benzene

    International Nuclear Information System (INIS)

    A system is described for the analysis of tritium (3H) in natural waters. The system consists of an electrolytic enrichment equipment and a vacuum line for benzene synthesis. The benzene is mixed with a scintillating solution and so used in tritium activity measurements by liquid scintillation spectrometry. The characteristcs of the system, as well as its performance, are pointed out through analysis of ground and rain waters. The precision and reproducibility of the measurements are discussed. (Author)

  8. Human risk assessment of benzene after a gasoline station fuel leak

    Directory of Open Access Journals (Sweden)

    Miriam dos Anjos Santos

    2013-06-01

    Full Text Available OBJECTIVE: To assess the health risk of exposure to benzene for a community affected by a fuel leak. METHODS: Data regarding the fuel leak accident with, which occurred in the Brasilia, Federal District, were obtained from the Fuel Distributor reports provided to the environmental authority. Information about the affected population (22 individuals was obtained from focal groups of eight individuals. Length of exposure and water benzene concentration were estimated through a groundwater flow model associated with a benzene propagation model. The risk assessment was conducted according to the Agency for Toxic Substances and Disease Registry methodology. RESULTS: A high risk perception related to the health consequences of the accident was evident in the affected community (22 individuals, probably due to the lack of assistance and a poor risk communication from government authorities and the polluting agent. The community had been exposed to unsafe levels of benzene (> 5 µg/L since December 2001, five months before they reported the leak. The mean benzene level in drinking water (72.2 µg/L was higher than that obtained by the Fuel Distributer using the Risk Based Corrective Action methodology (17.2 µg/L.The estimated benzene intake from the consumption of water and food reached a maximum of 0.0091 µg/kg bw/day (5 x 10-7 cancer risk per 106 individuals. The level of benzene in water vapor while showering reached 7.5 µg/m3 for children (1 per 104 cancer risk. Total cancer risk ranged from 110 to 200 per 106 individuals. CONCLUSIONS: The population affected by the fuel leak was exposed to benzene levels that might have represented a health risk. Local government authorities need to develop better strategies to respond rapidly to these types of accidents to protect the health of the affected population and the environment.

  9. RPBE-vdW Description of Benzene Adsorption on Au(111)

    DEFF Research Database (Denmark)

    Pedersen, Jess Wellendorff; Kelkkanen, Kari André; Mortensen, Jens Jørgen;

    2010-01-01

    der Waals interactions. The adsorption of benzene on Au(111) is an often mentioned such system where standard density functionals predict a very weak adsorption or even a repulsion, whereas a significant adsorption is observed experimentally. We show that a considerable improvement in the description...... of the adsorption of benzene on Au(111) is obtained when using the so-called RPBE-vdW functional....

  10. Molecular simulation study on Hofmeister cations and the aqueous solubility of benzene.

    Science.gov (United States)

    Ganguly, Pritam; Hajari, Timir; van der Vegt, Nico F A

    2014-05-22

    We study the ion-specific salting-out process of benzene in aqueous alkali chloride solutions using Kirkwood-Buff (KB) theory of solutions and molecular dynamics simulations with different empirical force field models for the ions and benzene. Despite inaccuracies in the force fields, the simulations indicate that the decrease of the Setchenow salting-out coefficient for the series NaCl > KCl > RbCl > CsCl is determined by direct benzene-cation correlations, with the larger cations showing weak interactions with benzene. Although ion-specific aqueous solubilities of benzene may be affected by indirect ion-ion, ion-water, and water-water correlations, too, these correlations are found to be unimportant, with little to no effect on the Setchenow salting-out coefficients of the various salts. We further considered LiCl, which is experimentally known to be a weaker salting-out agent than NaCl and KCl and, therefore, ranks at an unusual position within the Hofmeister cation series. The simulations indicate that hydrated Li(+) ions can take part of the benzene hydration shell while the other cations are repelled by it. This causes weaker Li(+) exclusion around the solute and a resulting, weaker salting-out propensity of LiCl compared to that of the other salts. Removing benzene-water and benzene-salt electrostatic interactions in the simulations does not affect this mechanism, which may therefore also explain the smaller effect of LiCl, as compared to that of NaCl or KCl, on aqueous solvation and hydrophobic interaction of nonpolar molecules. PMID:24792435

  11. (η6-Benzenedichlorido(dicyclohexylphenylphosphaneruthenium(II benzene sesquisolvate

    Directory of Open Access Journals (Sweden)

    Alfred Muller

    2012-12-01

    Full Text Available The asymmetric unit of the title compound, [RuCl2(C6H6(C18H27P]·1.5C6H6, contains one molecule of the RuII complex and one and a half solvent molecules as one of these is located about a centre of inversion. The RuII atom has a classical three-legged piano-stool environment being coordinated by an η6-benzene ligand [Ru—centroid = 1.6964 (6 Å], two chloride ligands with an average Ru—Cl bond length of 2.4138 (3 Å and a dicyclohexylphenylphosphane ligand [Ru—P = 2.3786 (3 Å]. The effective cone angle for the phosphane was calculated to be 158°. In the crystal, weak C—H...Cl hydrogen bonds link the RuII complexes into centrosymmetric dimers. The crystal packing exhibits intra- and intermolecular C—H...π interactions resulting in a zigzag pattern in the [101] direction.

  12. BENZENE FORMATION ON INTERSTELLAR ICY MANTLES CONTAINING PROPARGYL ALCOHOL

    International Nuclear Information System (INIS)

    Propargyl alcohol (CHCCH2OH) is a known stable isomer of the propenal (CH2CHCHO) molecule that was reported to be present in the interstellar medium (ISM). At astrochemical conditions in the laboratory, icy layers of propargyl alcohol grown at 85 K were irradiated by 2 keV electrons and probed by a Fourier Transform InfraRed spectrometer in the mid-infrared (IR) region, 4000-500 cm–1. Propargyl alcohol ice under astrochemical conditions was studied for the first time; therefore, IR spectra of reported amorphous (85 K) and crystalline (180 K) propargyl alcohol ices can be used to detect its presence in the ISM. Moreover, our experiments clearly show benzene (C6H6) formation to be the major product from propargyl alcohol irradiation, confirming the role of propargyl radicals (C3H3) formed from propargyl alcohol dissociation that was long expected based on theoretical modeling to effectively synthesize C6H6 in the interstellar icy mantles

  13. Vibrationally averaged dipole moments of methane and benzene isotopologues

    Science.gov (United States)

    Arapiraca, A. F. C.; Mohallem, J. R.

    2016-04-01

    DFT-B3LYP post-Born-Oppenheimer (finite-nuclear-mass-correction (FNMC)) calculations of vibrationally averaged isotopic dipole moments of methane and benzene, which compare well with experimental values, are reported. For methane, in addition to the principal vibrational contribution to the molecular asymmetry, FNMC accounts for the surprisingly large Born-Oppenheimer error of about 34% to the dipole moments. This unexpected result is explained in terms of concurrent electronic and vibrational contributions. The calculated dipole moment of C6H3D3 is about twice as large as the measured dipole moment of C6H5D. Computational progress is advanced concerning applications to larger systems and the choice of appropriate basis sets. The simpler procedure of performing vibrational averaging on the Born-Oppenheimer level and then adding the FNMC contribution evaluated at the equilibrium distance is shown to be appropriate. Also, the basis set choice is made by heuristic analysis of the physical behavior of the systems, instead of by comparison with experiments.

  14. Positronium formation and annihilation in BHDC/water/benzene microemulsions

    International Nuclear Information System (INIS)

    Positron lifetime measurements have been made on BHDC/water/benzene microemulsions, at different water to surfactant molar ratios (w0) and different surfactant concentrations (CBHDC). Recently, a model has been proposed to explain the positronium formation and annihilation in AOT/water/isooctane microemulsions, which states that the majority of positronium formation occurs in the aqueous cores of the reverse micelles, and the o-Ps there formed diffuses out of the aqueous cores into the organic solvent bulk. The BHDC based microemulsion system has been chosen in order to study the influence of the cationic head group and of the chloride counterion present in the aqueous pseudophase on the Ps formation probability and on the o-Ps diffusion out of the aqueous cores. The results of this study are satisfactorily explained by the referred model. The radii of the aqueous cores for different w0 values and calculated from the o-Ps lifetime measurements, are in good agreement with the values reported in the literature. The measured o-Ps intensities in both the aqueous pseudophase and the organic phase were found to be in agreement with those calculated by taking into account the partial inhibition due to the chloride counterions present in the aqueous cores. (orig.)

  15. BENZENE FORMATION ON INTERSTELLAR ICY MANTLES CONTAINING PROPARGYL ALCOHOL

    Energy Technology Data Exchange (ETDEWEB)

    Sivaraman, B.; Mukherjee, R.; Subramanian, K. P.; Banerjee, S. B., E-mail: bhala@prl.res.in [Space and Atmospheric Sciences Division, Physical Research Laboratory, Ahmedabad (India)

    2015-01-10

    Propargyl alcohol (CHCCH{sub 2}OH) is a known stable isomer of the propenal (CH{sub 2}CHCHO) molecule that was reported to be present in the interstellar medium (ISM). At astrochemical conditions in the laboratory, icy layers of propargyl alcohol grown at 85 K were irradiated by 2 keV electrons and probed by a Fourier Transform InfraRed spectrometer in the mid-infrared (IR) region, 4000-500 cm{sup –1}. Propargyl alcohol ice under astrochemical conditions was studied for the first time; therefore, IR spectra of reported amorphous (85 K) and crystalline (180 K) propargyl alcohol ices can be used to detect its presence in the ISM. Moreover, our experiments clearly show benzene (C{sub 6}H{sub 6}) formation to be the major product from propargyl alcohol irradiation, confirming the role of propargyl radicals (C{sub 3}H{sub 3}) formed from propargyl alcohol dissociation that was long expected based on theoretical modeling to effectively synthesize C{sub 6}H{sub 6} in the interstellar icy mantles.

  16. Multiple solutions of CCD equations for PPP model of benzene

    CERN Document Server

    Podeszwa, R; Jankowski, K; Rubiniec, K; Podeszwa, Rafa{\\l}; Stolarczyk, Leszek Z.; Jankowski, Karol; Rubiniec, Krzysztof

    2002-01-01

    To gain some insight into the structure and physical significance of the multiple solutions to the coupled-cluster doubles (CCD) equations corresponding to the Pariser-Parr-Pople (PPP) model of cyclic polyenes, complete solutions to the CCD equations for the A^{-}_{1g} states of benzene are obtained by means of the homotopy method. By varying the value of the resonance integral beta from -5.0 eV to -0.5 eV, we cover the so-called weakly, moderately, and strongly correlated regimes of the model. For each value of beta 230 CCD solutions are obtained. It turned out, however, that only for a few solutions a correspondence with some physical states can be established. It has also been demonstrated that, unlike for the standard methods of solving CCD equations, some of the multiple solutions to the CCD equations can be attained by means of the iterative process based on Pulay's direct inversion in the iterative subspace (DIIS) approach.

  17. Anaerobic degradation of alkylated benzenes in denitrifying laboratory aquifer columns

    International Nuclear Information System (INIS)

    Toluene and m-xylene were rapidly mineralized in an anaerobic laboratory aquifer column operated under continuous-flow conditions with nitrate as an electron acceptor. The oxidation of toluene and m-xylene was coupled with the reduction of nitrate, and mineralization was confirmed by trapping 14CO2 evolved from 14C-ring-labeled substrates. Substrate degradation also took place when nitrous oxide replaced nitrate as an electron acceptor, but decomposition was inhibited in the presence of molecular oxygen or after the substitution of nitrate by nitrite. The m-xylene-adapted microorganisms in the aquifer column degraded toluene, benzaldehyde, benzoate, m-toluylaldehyde, m-toluate, m-cresol, p-cresol, and p-hydroxybenzoate but were unable to metabolize benzene, naphthalene, methylcyclohexane, and 1,3-dimethylcyclohexane. Isotope-dilution experiments suggested benzoate as an intermediate formed during anaerobic toluene metabolism. The finding that the highly water-soluble nitrous oxide served as electron acceptor for the anaerobic mineralization of some aromatic hydrocarbons may offer attractive options for the in situ restoration of polluted aquifers

  18. Calcium- and CaMKII-dependent chloride secretion induced by the microsomal Ca(2+)-ATPase inhibitor 2,5-di-(tert-butyl)-1,4-hydroquinone in cystic fibrosis pancreatic epithelial cells.

    OpenAIRE

    Chao, A C; Kouyama, K; Heist, E K; Dong, Y. J.; Gardner, P

    1995-01-01

    Microsomal Ca(2+)-ATPase inhibitors such as thapsigargin (THG), cyclopiazonic acid (CPA) and 2,5-di-(tert-butyl)-1,4-hydroquinone (DBHQ) have been shown to inhibit Ca2+ reuptake by the intracellular stores and increase cytosolic free Ca2+ ([Ca2+]i). DBHQ is a commercially available non-toxic synthetic compound chemically unrelated to THG and CPA. In this study, we tested the feasibility of utilizing DBHQ to improve Cl- secretion via the Ca(2+)-dependent pathway, in the cystic fibrosis (CF)-de...

  19. Geogenic sources of benzene in aquifers used for public supply, California

    Science.gov (United States)

    Belitz, Kenneth; Landon, Matthew K.

    2012-01-01

    Statistical evaluation of two large statewide data sets from the California State Water Board's Groundwater Ambient Monitoring and Assessment Program (1973 wells) and the California Department of Public Health (12417 wells) reveals that benzene occurs infrequently (1.7%) and at generally low concentrations (median detected concentration of 0.024 μg/L) in groundwater used for public supply in California. When detected, benzene is more often related to geogenic (45% of detections) than anthropogenic sources (27% of detections). Similar relations are evident for the sum of 17 hydrocarbons analyzed. Benzene occurs most frequently and at the highest concentrations in old, brackish, and reducing groundwater; the detection frequency was 13.0% in groundwater with tritium 1600 μS/cm, and anoxic conditions. This groundwater is typically deep (>180 m). Benzene occurs somewhat less frequently in recent, shallow, and reducing groundwater; the detection frequency was 2.6% in groundwater with tritium ≥1 pCi/L, depth benzene include: higher concentrations and detection frequencies with increasing well depth, groundwater age, and proximity to oil and gas fields; and higher salinity and lower chloride/iodide ratios in old groundwater with detections of benzene, consistent with interactions with oil-field brines.

  20. Protective effects of zinc and selenium against benzene toxicity in rats.

    Science.gov (United States)

    Ibrahim, Khadiga S; Saleh, Zeinab A; Farrag, Abdel-Razik H; Shaban, Eman E

    2011-07-01

    The presented study investigates the protective role of zinc (Zn) and selenium (Se) in attenuating benzene-induced toxicity in rats. Male Sprague-Dawley rats were injected with benzene (0.5 mL/kg body weight ip) and received a diet supplement containing Zn and Se. Several hematological and biochemical parameters (representing antioxidant status) were estimated. Histopathological examinations were performed. Results showed that food intake and body weight gain of benzene-injected rats were significantly lower than that of the control rats. Benzene-injected rats showed increased plasma malondialdehyde (MDA) and decreased activity of: glutathione peroxidase (GSH-Px), catalase, superoxide dismutase (SOD) enzymes, as well as reduced glutathione (GSH) when compared to the control group. Histopathological investigations revealed structural changes in benzene-injected rats' liver. Supplementation with Zn and Se resulted in a significant decrease in MDA, elevation in GSH, GSH-Px, SOD and catalase levels. This study shows that Zn and Se supplementation can improve the activity of antioxidant enzymes in rats and decrease the histological anomalies induced by benzene toxicity as well. PMID:21511895

  1. Urinary estrogen metabolites and breast cancer

    DEFF Research Database (Denmark)

    Dallal, Cher M; Stone, Roslyn A; Cauley, Jane A;

    2013-01-01

    Background: Circulating estrogens are associated with increased breast cancer risk, yet the role of estrogen metabolites in breast carcinogenesis remains unclear. This combined analysis of 5 published studies evaluates urinary 2-hydroxyestrone (2-OHE1), 16a-hydroxyestrone (16a-OHE1), and their...... ratio (2:16a-OHE1) in relation to breast cancer risk. ¿Methods: Primary data on 726 premenopausal women (183 invasive breast cancer cases and 543 controls) and 1,108 postmenopausal women (385 invasive breast cancer cases and 723 controls) were analyzed. Urinary estrogen metabolites were measured using...... enzyme linked immunosorbent assays. Study-specific and combined multivariable adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated based on tertiles of estrogen metabolites. Multinomial logistic regression models were fit according to hormone receptor status.¿Results: Higher...

  2. Transporter and its engineering for secondary metabolites.

    Science.gov (United States)

    Lv, Huajun; Li, Jianhua; Wu, Yingying; Garyali, Sanjog; Wang, Yong

    2016-07-01

    Secondary metabolites possess a lot of biological activities, and to achieve their functions, transmembrane transportation is crucial. Elucidation of their transport mechanisms in the cell is critical for discovering ways to improve the production. Here, we have summarized the recent progresses for representative secondary metabolite transporters and also the strategies for uncovering the transporter systems in plants and microbes. We have also discussed the transporter engineering strategies being utilized for improving the heterologous natural product production, which exhibits promising future under the guide of synthetic biology. PMID:27209041

  3. [Autism and Autism-associated Metabolites].

    Science.gov (United States)

    Watanabe, Kunitomo

    2016-06-01

    Gene-microbiota interactions are now proposed to be a special case of gene-environmental interaction. Preclinical and clinical data summarized in this article reveal that a specific serum metabolite, associated with alterations in gut microbiome composition, might have an emerging role in the onset and pathogenesis of autism. Altered level of this specified metabolite may induce perturbations in the epigenome and modulate the expression of key disease susceptible genes in neurons and their associated cells during critical periods of neurodevelopment. The gut microbiota itself is now regarded as a reservoir for environmental epigenetic factors. PMID:27279160

  4. Animal bioavailability of defined xenobiotic lignin metabolites

    International Nuclear Information System (INIS)

    Lignin has been recognized as a major component of bound pesticide residues in plants and is thought to be undigestible in animals. Two defined ring-U-14C-labeled chloroaniline/lignin metabolites have now been fed to rats, where a release of ∼66% of the bound xenobiotic occurred in the form of simple chloroaniline derivatives. The observed high degree of bioavailability indicates that bound pesticidal residues may possess ecotoxicological significance. In parallel studies, the white-rot fungus Phanerochaete chrysosporium was more efficient, and a soil system was much less efficient, in the degradation of the [ring-U-14C]chloroaniline/lignin metabolites

  5. Metabolites from mangrove endophytic fungus Dothiorella sp.

    Institute of Scientific and Technical Information of China (English)

    XUQingyan; WANGJianfeng; HUANGYaojian; ZHENGZhonghui; SONGSiyang; ZHANGYongmin; SUWenjin

    2004-01-01

    Mangroves are special woody plant communities in the intertidal zone of tropical and subtropical coasts. They prove to be a natural microorganisms and new metabolites storage. In the study of mangrove endophytic fungi metabolites, four new compounds, Compounds 1, 2, 3 and 4, as well as a known octaketide, cytosporone B (5), are isolated from an endophytic fungus, Dothiorella sp., HTF3. They all show cytotoxic activities. The elucidation of these structures is mainly based on 1D/2D NMR and ESI-MS spectral analyses.

  6. Test of electron beam technology on Savannah River Laboratory low-activity aqueous waste for destruction of benzene, benzene derivatives, and bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Dougal, R.A. [Univ. of South Carolina, Columbia, SC (United States). Dept. of Electrical and Computer Engineering

    1993-08-01

    High energy radiation was studied as a means for destroying hazardous organic chemical wastes. Tests were conducted at bench scale with a {sup 60}Co source, and at full scale (387 l/min) with a 1.5 MV electron beam source. Bench scale tests for both benzene and phenol included 32 permutations of water quality factors. For some water qualities, as much as 99.99% of benzene or 90% of phenol were removed by 775 krads of {sup 60}Co irradiation. Full scale testing for destruction of benzene in a simulated waste-water mix showed loss of 97% of benzene following an 800 krad dose and 88% following a 500 krad dose. At these loss rates, approximately 5 Mrad of electron beam irradiation is required to reduce concentrations from 100 g/l to drinking water quality (5 {mu}g/l). Since many waste streams are also inhabited by bacterial populations which may affect filtering operations, the effect of irradiation on those populations was also studied. {sup 60}Co and electron beam irradiation were both lethal to the bacteria studied at irradiation levels far lower than were necessary to remove organic contaminants.

  7. Test of electron beam technology on Savannah River Laboratory low-activity aqueous waste for destruction of benzene, benzene derivatives, and bacteria

    International Nuclear Information System (INIS)

    High energy radiation was studied as a means for destroying hazardous organic chemical wastes. Tests were conducted at bench scale with a 60Co source, and at full scale (387 l/min) with a 1.5 MV electron beam source. Bench scale tests for both benzene and phenol included 32 permutations of water quality factors. For some water qualities, as much as 99.99% of benzene or 90% of phenol were removed by 775 krads of 60Co irradiation. Full scale testing for destruction of benzene in a simulated waste-water mix showed loss of 97% of benzene following an 800 krad dose and 88% following a 500 krad dose. At these loss rates, approximately 5 Mrad of electron beam irradiation is required to reduce concentrations from 100 g/l to drinking water quality (5 μg/l). Since many waste streams are also inhabited by bacterial populations which may affect filtering operations, the effect of irradiation on those populations was also studied. 60Co and electron beam irradiation were both lethal to the bacteria studied at irradiation levels far lower than were necessary to remove organic contaminants

  8. Survey results of benzene in soft drinks and other beverages by headspace gas chromatography/mass spectrometry.

    Science.gov (United States)

    Nyman, Patricia J; Diachenko, Gregory W; Perfetti, Gracia A; McNeal, Timothy P; Hiatt, Michael H; Morehouse, Kim M

    2008-01-23

    Benzene, a carcinogen that can cause cancer in humans, may form at nanogram per gram levels in some beverages containing both benzoate salts and ascorbic or erythorbic acids. Through a series of reactions, a hydroxyl radical forms that can decarboxylate benzoate to form benzene. Elevated temperatures and light stimulate these reactions, while sugar and ethylenediaminetetraacetic acid (EDTA) can inhibit them. A headspace gas chromatography/mass spectrometry method for the determination of benzene in beverages was developed and validated. The method was used to conduct a survey of 199 soft drinks and other beverages. The vast majority of beverages sampled contained either no detectable benzene or levels below the U.S. Environmental Protection Agency's drinking water limit of 5 ng/g. Beverages found to contain 5 ng/g benzene or more were reformulated by the manufacturers. The amount of benzene found in the reformulated beverages ranged from none detected to 1.1 ng/g. PMID:18072742

  9. Biodegradation of methane, benzene, and toluene by a consortium MBT14 enriched from a landfill cover soil.

    Science.gov (United States)

    Lee, Eun-Hee; Park, Hyunjung; Cho, Kyung-Suk

    2013-01-01

    In this study, landfill cover soil was used as an inoculum source to enrich a methane, benzene, and toluene-degrading consortium MBT14. Under a single substrate, the maximum degradation rates of methane, benzene and toluene were 1.96, 0.15, and 0.77 mmole g-DCW(-1) h(-1), respectively. Although the coexistence of benzene and toluene inhibited the methane degradation rates, the consortium was able to simultaneously degrade methane, benzene and toluene. Methane had an insignificant effect on benzene or toluene degradation. Based on 16S rDNA sequencing analysis, Cupriavidus spp. are dominant in the consortium MBT14. The combined results of this study indicate that the consortium MBT 14 is a promising bioresource for removing CH(4), benzene, and toluene from a variety of environments. PMID:23245302

  10. Simultaneous determination of hydroquinone, resorcinol, phenol, m-cresol and p-cresol in untreated air samples using spectrofluorimetry and a custom multiple linear regression-successive projection algorithm.

    Science.gov (United States)

    Pistonesi, Marcelo F; Di Nezio, María S; Centurión, María E; Lista, Adriana G; Fragoso, Wallace D; Pontes, Márcio J C; Araújo, Mário C U; Band, Beatriz S Fernández

    2010-12-15

    In this study, a novel, simple, and efficient spectrofluorimetric method to determine directly and simultaneously five phenolic compounds (hydroquinone, resorcinol, phenol, m-cresol and p-cresol) in air samples is presented. For this purpose, variable selection by the successive projections algorithm (SPA) is used in order to obtain simple multiple linear regression (MLR) models based on a small subset of wavelengths. For comparison, partial least square (PLS) regression is also employed in full-spectrum. The concentrations of the calibration matrix ranged from 0.02 to 0.2 mg L(-1) for hydroquinone, from 0.05 to 0.6 mg L(-1) for resorcinol, and from 0.05 to 0.4 mg L(-1) for phenol, m-cresol and p-cresol; incidentally, such ranges are in accordance with the Argentinean environmental legislation. To verify the accuracy of the proposed method a recovery study on real air samples of smoking environment was carried out with satisfactory results (94-104%). The advantage of the proposed method is that it requires only spectrofluorimetric measurements of samples and chemometric modeling for simultaneous determination of five phenols. With it, air is simply sampled and no pre-treatment sample is needed (i.e., separation steps and derivatization reagents are avoided) that means a great saving of time. PMID:21111140

  11. Canada-wide standard for benzene phase 1 : Progress report 2001

    International Nuclear Information System (INIS)

    In June 2000, the Canadian Council of Ministers of the Environment (CCME) ratified the Canada-Wide Standard (CWS) for Benzene Phase 1. Benzene is classified as a carcinogen to humans and any level of exposure is generally considered to carry some probability of harmful effects. The Ministers committed to reducing national benzene emissions by 30 per cent between 1995 and 2000. This report presents the progress thus far and describes how the Alberta Government has focused on effecting emission reductions in the natural gas sector, dehydrators, petroleum refineries and in chemical manufacturing plants. Their initiatives led to a 66 per cent decrease in benzene emissions by 1999. In addition, overall emissions in the province were reduced by 50 per cent from industry and mobile sources. The measures initiated during Phase 1 will continue beyond the time frame, and Phase 2, not yet ratified, will call for a follow-through on those measures. Phase 2 recognizes best management practices and jurisdictional regulations that will minimize emissions. Specifically, Phase 2 calls for an additional reduction of 6 kilotonnes in benzene emissions for existing facilities by the end of 2010. The minimization of benzene emissions through the application of best available pollution prevention and control techniques is contained for new and expanding facilities. The implementation of the CWS comprises the follow-up of existing initiatives resulting from the application of Phase 1 and the promotion and application of best management practices for new and expanding facilities, the determination and tracking of ancillary emission reductions of benzene realized as a result of other CWS initiatives, and the monitoring and reporting of progress. 13 refs., 4 tabs., 3 figs

  12. Benzene and lead exposure assessment among occupational bus drivers in Bangkok traffic

    Institute of Scientific and Technical Information of China (English)

    SHING TET LEONG; PREECHA LAORTANAKUL

    2004-01-01

    Four environmental and biological monitoring sites were strategically established to evaluate benzene and lead exposure assessment at various traffic zones of Bangkok Metropolitan Region(BMR). Biological measurement of 48 non air-conditioned, male bus drivers was carried to study the relationship between individual exposure levels and exposure biomarkers. The study group was further subdivided into four age groups( 16-25, 26-35, 36-45 and 46-55 years old) to monitor the age-related exposure effects. A total of 12unexposed persons were deliberately chosen as the control group. Measurement of unmetobolized benzene in blood and analysis of urinary tt-Muconic acid urine and urinary creatinine are recommended as biomarkers of benzene exposure. Measurement of lead in blood and urine is also recommended for the biological monitoring of lead exposure.During the monitoring period, benzene and lead levels at Yaowarat Road was C6H6: 42.46 + 3.88 μg/m3 , Pb: 0.29 + 0.03 μg/m3 and decreased to C6 H6: 33.5 ± 1.35 μg/m3 , Pb: O. 13 + 0.01 μg/m3 at Phahonyothin Road. Significant difference was established between the nonsmoking exposed group and nonsmoking control group for blood benzene concentrations ( P < 0.001, two-tailed, Mann-Whiteney U test). Strong correlations were also found between trans-trans-Muconic acid concentrations in post shift samples and atmospheric benzene concentrations. Similarly, good correlation between all of biomarkers and lead level in air is established from automobile emissions.The analysis revealed that among the occupational population in the urban sites, the driver groups were found to have the highest risk of benzene and lead exposures derived from automobile emission.

  13. Benzene and lead exposure assessment among occupational bus drivers in Bangkok traffic.

    Science.gov (United States)

    Muttamara, S; Leong, Shing Tet; Arayasiri, M

    2004-01-01

    Four environmental and biological monitoring sites were strategically established to evaluate benzene and lead exposure assessment at various traffic zones of Bangkok Metropolitan Region(BMR). Biological measurement of 48 non air-conditioned, male bus drivers was carried to study the relationship between individual exposure levels and exposure biomarkers. The study group was further subdivided into four age groups(16-25, 26-35, 36-45 and 46-55 years old) to monitor the age-related exposure effects. A total of 12 unexposed persons were deliberately chosen as the control group. Measurement of unmetobolized benzene in blood and analysis of urinary tt-Muconic acid urine and urinary creatinine are recommended as biomarkers of benzene exposure. Measurement of lead in blood and urine is also recommended for the biological monitoring of lead exposure. During the monitoring period, benzene and lead levels at Yaowarat Road was C6H6: 42.46 +/- 3.88 microg/m3 , Pb: 0.29 +/- 0.03 microg/m3 and decreased to C6H6: 33.5 +/- 1.35 microg/m3, Pb: 0.13 +/- 0.01 microg/m3 at Phahonyothin Road. Significant difference was established between the nonsmoking exposed group and nonsmoking control group for blood benzene concentrations (P < 0.001, two-tailed, Mann-Whiteney U test). Strong correlations were also found between trans-trans-Muconic acid concentrations in post shift samples and atmospheric benzene concentrations. Similarly, good correlation between all of biomarkers and lead level in air is established from automobile emissions. The analysis revealed that among the occupational population in the urban sites, the driver groups were found to have the highest risk of benzene and lead exposures derived from automobile emission. PMID:14971454

  14. Separation of several alcohol-benzene mixtures by pervaporation through styrene graft polyethylene membranes

    International Nuclear Information System (INIS)

    The permeation of pure liquids, such as methanol, ethanol, 1-propanol, 2-propanol and benzene, and the permeability and selectivity of 50 vol% binary mixtures of these alcohols and benzene were investigated by pervaporation technique. The used membranes (21%, 40%, and 72% graftings) were obtained by graft polymerization of styrene to polyethylene film (thickness 10 μm) by γ-radiation. The permeation rates of each of these alcohols and benzene were measured by pervaporation through the graft membranes. Those of these alcohols were very small as well as those through the original membrane. On the other hand, the permeabilities for benzene through the graft membranes were larger than that through the original membrane. The temperature dependence of the permeation rate for benzene was expressed by Arrhenius-type relationships, and the apparent activation energies were calculated to be 10.7 (21%), 10.2 (40%) and 10.0 (72%) kcal/mol. In the permeation of 50 vol% several alcohol-benzene mixtures, the permeabilities through the graft membranes were also larger than that through the original membrane, and increased with the grafting. The temperature dependence of the permeation for these mixtures was showed by Arrhenius relationships, and the apparent activation energies were calculated to be in the range of 8.4∼11.0 kcal/mol. The separation factors of the graft membranes calculated from composition of the permeates were always smaller than that of the original membrane, but became larger with increase of molecular volume of alcohol in alcohol-benzene mixtures. (author)

  15. Characterization of changes in gene expression and biochemical pathways at low levels of benzene exposure.

    Directory of Open Access Journals (Sweden)

    Reuben Thomas

    Full Text Available Benzene, a ubiquitous environmental pollutant, causes acute myeloid leukemia (AML. Recently, through transcriptome profiling of peripheral blood mononuclear cells (PBMC, we reported dose-dependent effects of benzene exposure on gene expression and biochemical pathways in 83 workers exposed across four airborne concentration ranges (from 10 ppm compared with 42 subjects with non-workplace ambient exposure levels. Here, we further characterize these dose-dependent effects with continuous benzene exposure in all 125 study subjects. We estimated air benzene exposure levels in the 42 environmentally-exposed subjects from their unmetabolized urinary benzene levels. We used a novel non-parametric, data-adaptive model selection method to estimate the change with dose in the expression of each gene. We describe non-parametric approaches to model pathway responses and used these to estimate the dose responses of the AML pathway and 4 other pathways of interest. The response patterns of majority of genes as captured by mean estimates of the first and second principal components of the dose-response for the five pathways and the profiles of 6 AML pathway response-representative genes (identified by clustering exhibited similar apparent supra-linear responses. Responses at or below 0.1 ppm benzene were observed for altered expression of AML pathway genes and CYP2E1. Together, these data show that benzene alters disease-relevant pathways and genes in a dose-dependent manner, with effects apparent at doses as low as 100 ppb in air. Studies with extensive exposure assessment of subjects exposed in the low-dose range between 10 ppb and 1 ppm are needed to confirm these findings.

  16. Bioremediation of benzene-, MTBE- and ammonia-contaminated groundwater with pilot-scale constructed wetlands

    International Nuclear Information System (INIS)

    In this pilot-scale constructed wetland (CW) study for treating groundwater contaminated with benzene, MTBE, and ammonia-N, the performance of two types of CWs (a wetland with gravel matrix and a plant root mat) was investigated. Hypothesized stimulative effects of filter material additives (charcoal, iron(III)) on pollutant removal were also tested. Increased contaminant loss was found during summer; the best treatment performance was achieved by the plant root mat. Concentration decrease in the planted gravel filter/plant root mat, respectively, amounted to 81/99% for benzene, 17/82% for MTBE, and 54/41% for ammonia-N at calculated inflow loads of 525/603 mg/m2/d, 97/112 mg/m2/d, and 1167/1342 mg/m2/d for benzene, MTBE, and ammonia-N. Filter additives did not improve contaminant depletion, although sorption processes were observed and elevated iron(II) formation indicated iron reduction. Bacterial and stable isotope analysis provided evidence for microbial benzene degradation in the CW, emphasizing the promising potential of this treatment technique. - Highlights: → BTEX compounds contaminated groundwater can be efficiently treated by CWs. → The removal efficiency depended on CW type, season and contaminant. → The plant root mat revealed better treatment results than the gravel filter CW. → Best results achieved by the plant root mat (99% benzene concentration decrease). → Stable isotope analysis and MPN indicated high benzene remediation potential. - Gravel bed constructed wetlands and a plant root mat system efficiently eliminated fuel hydrocarbons (benzene, MTBE) and ammonia-N from groundwater at a pilot-scale.

  17. 氢醌对 K562细胞着色性干皮病基因 D转录及表达的影响%Effects of Hydroquinone on Transcription and Expression of XPD Gene in K562 Cells

    Institute of Scientific and Technical Information of China (English)

    万秀方; 郑丹; 张越时; 龚骏杰; 肖芸; 张亚莉; 杨国珍

    2015-01-01

    目的:探讨苯代谢物氢醌( HQ)对人白血病细胞株K562细胞中着色性干皮病基因D( XPD)mRNA转录及蛋白表达的影响。方法:分别用终浓度为0、15、30、60μmol/L HQ溶液处理K562细胞48 h后,单细胞凝胶电泳实验检测细胞DNA损伤效应,Taqman探针实时荧光定量PCR法检测XPD基因mRNA转录水平,蛋白印迹法分析XPD基因蛋白表达水平,观察荧光显微镜下细胞的尾矩,计算mRNA及蛋白的相对表达量。结果:不同浓度HQ处理后,各组细胞尾矩与0μmol/L HQ组比较,差异有统计学意义( P<0.05);不同浓度HQ处理后, K562细胞中XPD基因mRNA和蛋白相对表达量与0μmol/L HQ组比较,差异无统计学意义( P>0.05)。结论:HQ处理K562细胞48 h后,细胞中DNA有明显的损伤效应,但XPD基因mRNA及蛋白无变化。%Objective:To explore effects of different concentration of hydroquinone( HQ)on mRNA transcription and protein expression of xeroderma pigmentosum group D( XPD )in Human leukemia cell line K562 cells. Methods:K562 cells were treated and contaminated with 0,15,30,60 μmol/L hydroquinone for 48h,respectively. The DNA damage effect of the cells exposed to hydroquinone was detected by single cell gel electrophoresis. The mRNA transcription of XPD was detected by Taq-man probe real-time fluorescence quantitative PCR. The protein expression of XPD was detected by Western blot. Results:In DNA damage effect experiment,there existed significant differences in the tail moment between contamination groups and control group(0 μmol/L hydroquinone)(P0. 05). Conclusion:After K562 cells are treated with hydroquinone for 48 h, the DNA damage effect of K562 cells is obvious. But the change of mRNA transcription and protein ex-pression of XPD can not be found.

  18. Effects of Hydroquinone on Methylation of XPD Gene in K562 Cells%氢醌对K562细胞着色性干皮病基因D甲基化的影响

    Institute of Scientific and Technical Information of China (English)

    万秀方; 肖芸; 郑丹; 张越时; 龚俊杰; 张亚莉; 杨国珍

    2015-01-01

    目的:了解不同剂量苯代谢物氢醌( HQ)对人白血病细胞株K562细胞着色性干皮病基因D( XPD)甲基化水平的影响。方法:分别以终浓度为0、15、30和60μmol/L HQ溶液重复处理K562细胞48 h,采用MTT比色法检测K562细胞增殖能力,采用亚硫酸氢盐处理后测序法检测XPD甲基化水平;观察各组细胞存活率及甲基化率。结果:HQ 0、15、30、60μmol/L 处理后,K562细胞存活率分别为(100.00±0.00)%、(85.46±0.60)%、(63.46±7.02)%和(51.20±6.49)%,15μmol/L 组与0μmol/L 组比较,差异无统计学意义( P >0.05),30μmol/L和60μmol/L组与0μmol/L组比较,差异有统计学意义(P<0.05);XPD基因甲基化水平分别依次为1.03%(3/290)、0.34%(1/290)、0.34%(1/290)和0.70%(2/290),15、30、60μmol/L组与0μmol/L组比较,差异无统计学意义(χ2=1.531,P>0.05)。结论:HQ对K562细胞生长有明显的抑制作用,但对细胞中XPD基因甲基化水平无影响。%Objective:To investigate the effect of different dose of hydroquinone on methylation of xeroderma pigmentosum group D(XPD)in K562 cells. Methods:K562 cells were treated with 0,15, 30 and 60 μmol/L of hydroquinone solution for 48 h repeatedly. The inhibition of hydroquinone on K562 cell proliferation was studied by MTT assay. It was first handled by bisulfite then adopting se-quencing PCR( BSP)to test methylate level of XPD. Observing the cell survival rate and gene methyl-ation rate. Results:After being treated with 0,15,30 and 60 μmol/L of hydroquinone solution, K562 cells survival rates were( 100 . 00 ± 0 . 00 )%,( 85 . 46 ± 0 . 60 )%,( 63 . 46 ± 7 . 02 )% and (51. 20 ± 6. 49)% respectively. Comparing 15 μmol/L group and 0 μmol/L group,the differences were not statistically significant(P>0. 05);comparing 30 μmol/L and 60 μmol/L group,the differ-ences were statistically significant( P0. 05). Conclusion:Hydroquinone

  19. Effect of benzene on product evolution in a H2S/O2 flame under Claus condition

    International Nuclear Information System (INIS)

    Highlights: • Effect of trace amounts of benzene (0.3%, 0.5% and 1%) to H2S combustion process. • Benzene favored formation of H2 and reduced conversion of H2S. • Benzene reduced SO2 formation to impact sulfur production. • Benzene addition promoted CO and COS formation and degraded sulfur quality. - Abstract: Experimental results are presented on the role of benzene addition to H2S combustion at an equivalence ratio of three with respect to H2S (Claus condition) and complete combustion of benzene. The results are reported with 0.3%, 0.5% and 1% benzene addition to H2S/O2 flame. Combustion of H2S and benzene mixtures is of practical value for sulfur recovery during combustion of acid gases. The results showed that H2S combustion caused H2S to decompose to a minimum mole fraction with high conversion of H2S while the SO2 mole fraction reached a maximum value. Addition of benzene decreased the conversion of H2S with reduced mole fraction of SO2 in the reactor to subsequently reduce the formation of elemental sulfur. Benzene also caused significant production of H2, CO and COS formation along with faster decomposition of the formed SO2. Presence of benzene, even in trace amounts, in acid gas hinders sulfur conversion in a Claus reactor and increases emission of unwanted sulfur bearing compounds. Increased hydrogen production with benzene offers potential value for hydrogen recovery under certain conditions

  20. Evaluation of Trans, Trans-Muconic Acid in Urine of Exposed Workers to Benzene in a Cokery Plant

    OpenAIRE

    M. Rahiminejad; S.Gh. Mirsattari; A. Bahrami; B. Akbari

    2006-01-01

    Introduction & Objective: Benzene is a light yellow liquid with aromatic odor and has effects to human body. The main and dangerous health effect of chronic exposure to benzene in workplace is hematopoetic system disease or blood cancer that it's primarily clinical figures are anemia, leucopenia, thrombocytopenia. The objective of this study was evaluation of benzene exposure by analysis of urinary trans, trans-muconic acid (t,t-ma) in post shift of workers.Materials & Methods: A case-contro...