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Sample records for musk xylene chemical

  1. Dermal absorption and disposition of musk ambrette, musk ketone and musk xylene in human subjects.

    Science.gov (United States)

    Hawkins, David R; Elsom, Lionel F; Kirkpatrick, David; Ford, Richard A; Api, Anne Marie

    2002-05-28

    Musk ambrette, musk ketone and musk xylene have a long history of use as fragrance ingredients, although musk ambrette is no longer used in fragrances. As part of the review of the safety of these uses, it is important to consider the systemic exposure that results from these uses. Since the primary route of exposure to fragrances is on the skin, dermal doses of carbon-14 labelled musk ambrette, musk ketone and musk xylene were applied to the backs (100 cm2) of healthy human volunteers (two to three subjects) at a nominal dose level of 10-20 microg/cm2 and excess material removed at 6 h. Means of 2.0% musk ambrette, 0.5% musk ketone and 0.3% musk xylene were absorbed based on the amounts excreted in urine and faeces during 5 days. Most of the material was excreted in the urine with less than 10% of the amount excreted being found in faeces. No radioactivity was detected in any plasma sample, consistent with low absorption, and no radioactivity was detected (<0.02% dose) in skin strips taken at 120 h. Analysis of urine samples indicated that all three compounds were excreted mainly as single glucuronide conjugates. The aglycones were chromatographically different, but of similar polarity, to the major rat metabolites excreted in bile also as glucuronides.

  2. DETERMINATION OF A BOUND MUSK XYLENE ...

    Science.gov (United States)

    Musk xylene (MX) is widely used as a fragrance ingredient in commercial toiletries. Identification and quantification of a bound 4-amino-MX (AMX) metabolite was carried out by gas chromatography-mass spectrometry (GC/MS), with selected ion monitoring (SIM). Detection of AMX occurred after the cysteine adducts in carp hemoglobin, derived from the nitroso metabolite, were released by alkaline hydrolysis. The released AMX metabolite was extracted into n-hexane. The extract was preconcentrated by evaporation, and analyzed by GC-SIM-MS. The concentration of AMX metabolite was found to range from 6.0 to 30.6 ng/g in the carp Hb, collected from the Las Vegas Wash and Lake Mead, Nevada areas. The presence of an AMX metabolite in the carp Hb was confirmed when similar mass spectral features and the same retention time of the AMX metabolite were obtained for both standard AMX and carp Hb extract solutions. In the non-hydrolyzed and reagent blank extracts, the AMX metabolite was not detected. The research focused on in the subtasks is the development and application of state-of the-art technologies to meet the needs of the public, Office of Water, and ORD in the area of Water Quality. Located In the subtasks are the various research projects being performed in support of this Task and more in-depth coverage of each project. Briefly, each project's objective is stated below.Subtask 1: To integrate state-of-the-art technologies (polar organic chemical integrative samplers,

  3. Xylenes

    International Nuclear Information System (INIS)

    1993-01-01

    In Canada, xylenes are produced from the catalytic reforming of petroleum and as byproducts from the cracking of oil. An estimated 2,600 kilotonnes/y is consumed in Canada as a component of gasoline; 145 kilotonnes/y of purified xylenes are also consumed for other uses such as solvents. Xylenes are released into the air principally from their use as solvents and from transportation sources, and into soil and water through spills and leakage of petroleum and other chemical products. These releases have resulted in the presence of measurable concentrations of xylenes in air, water, and soil in Canada, although xylenes do not persist in any of these media. Although most xylenes are released into the air, concentrations to which wildlife are exposed are at least 1,000 times less than the effects threshold estimated for inhalation of xylenes by mammals. Xylene levels in ambient air are at least a million times less than the effects threshold recorded for plants. Concentrations of xylenes in surface water are at least 100 times less than the effects threshold estimated for the most sensitive aquatic species. Xylenes are not expected to be associated with global warming or ozone depletion. Based on data on concentrations of xylenes in ambient air, drinking water, and at self-serve gasoline stations, the total average daily intake of xylenes was estimated for various age groups in the general population. This intake is 15-45 times less than the tolerable daily intake derived on the basis of laboratory studies. It is concluded that xylenes are not entering the environment in quantities or under conditions that may be harmful to the environment, or that may constitute a danger to the environment on which human life depends, or to human life or health. 123 refs., 2 tabs

  4. DETERMINATION OF A BOUND MUSK XYLENE METABOLITE IN CARP HEMOGLOBIN AS A BIOMARKER OF EXPOSURE BY GAS CHROMATOGRAPHY MASS SPECTROMETRY USING SELECTED ION MONITORING

    Science.gov (United States)

    Musk xylene (MX) is widely used as a fragrance ingredient in commercial toiletries. Identification and quantification of a bound 4-amino-MX (AMX) metabolite was carried out by gas chromatography-mass spectrometry (GC/MS), with selected ion monitoring (SIM). Detection of AMX occur...

  5. NITRO MUSK BOUND TO CARP HEMOGLOBIN ...

    Science.gov (United States)

    Nitroaromatic compounds including synthetic nitro musks are important raw materials and intermediates in the synthesis of explosives, dyes, and pesticides, pharmaceutical and personal care-products (PPCPs). The nitro musks such as musk xylene (MX) and musk ketone (MK) are extensively used as fragrance ingredients in PPCPs and other commercial toiletries. Identification and quantification of a bound 4-amino-MX (4-AMX) metabolite as well as a 2- amino-MK (2-AMK) metabolite were carried out by gas chromatography-mass spectrometry' (GC/MS), with selected ion monitoring (SIM) in both the electron ionization (ElMS) and electron capture (EC) negative ion chemical ionization (NICIMS) modes. Detection of 4-AMX and 2-AMK occurred after the cysteine adducts in carp hemoglobin, derived from the nitroso metabolites, were released by alkaline hydrolysis. The released metabolites were extracted into n-hexane. The extract was preconcentrated by evaporation, and analyzed by GC-SIM-MS. A comparison between the El and EC approaches was made. EC NICIMS detected both metabolites whereas only 4-AMX was detected by ElMS. The EC NICIMS approach exhibited fewer matrix responses and provided a lower detection limit. Quantitation in both approaches was based on internal standard and a calibration plot. The research focused on in the subtasks is the development and application of state-of the-art technologies to meet the needs of the public, Office of Water, and ORD in the area of Water Q

  6. Evaluation of Simple Treat 3.0 for two hydrophobic and slowly biodegradable chemicals: Polycyclic musks HHCB and AHTN

    NARCIS (Netherlands)

    Artola-Garicano, E.; Hermens, J.L.M.; Vaes, W.H.J.

    2003-01-01

    In the current study, predictions by Simple Treat 3.0, a fate model for organic chemicals in sewage treatment plants (STPs), are compared with actual measurements in three STPs. Two polycyclic musks, Tonalide® (AHTN) and Galaxolide® (HHCB), were used for model evaluation. Results show that Simple

  7. NITRO MUSK BOUND TO CARP HEMOGLOBIN: DETERMINATION BY GC WITH TWO MS DETECTION MODES: EIMS VERSUS ELECTRON CAPTURE NEGEATIVE ION MS

    Science.gov (United States)

    Nitroaromatic compounds including synthetic nitro musks are important raw materials and intermediates in the synthesis of explosives, dyes, and pesticides, pharmaceutical and personal care-products (PPCPs). The nitro musks such as musk xylene (MX) and musk ketone (MK) are extensi...

  8. Synthetic Musk Fragrances in a Conventional Drinking Water Treatment Plant with Lime Softening

    OpenAIRE

    Wombacher, William D.; Hornbuckle, Keri C.

    2009-01-01

    Synthetic musk fragrances are common personal care product additives and wastewater contaminants that are routinely detected in the environment. This study examines the presence eight synthetic musk fragrances (AHTN, HHCB, ATII, ADBI, AHMI, musk xylene, and musk ketone) in source water and the removal of these compounds as they flow through a Midwestern conventional drinking water plant with lime softening. The compounds were measured in water, waste sludge, and air throughout the plant. HHCB...

  9. NITRO MUSK ADDUCTS OF RAINBOW TROUT ...

    Science.gov (United States)

    Rainbow trout and other fish species can serve as 'sentinel' species for the assessment of ecological status and the presence of certain environmental contaminants. As such they act as bioindicators of exposure. Here we present seminal data regarding dose-response and toxicokinetics of trout hemoglobin adduct formation from exposure to nitro musks that are frequently used as fragrance ingredients in formulations of personal care products. Hemoglobin adducts serve as biomarkers of exposure of the sentinel species as we have shown in previous studies of hemoglobin adducts formed in trout and environmental carp exposed to musk xylene (MX) and musk ketone (MK). Gas chromatography-electron capture negative ion chemical ionization-mass spectrometry (GC-NICI-MS) employing selected ion monitoring is used to measure 4-amino-MX (4-AMX), 2-amino-MX (2-AMX), and 2-amino-MK (2-AMK) released by alkaline hydrolysis from the sulfinamide adducts of hemoglobin. Dose-response and toxicokinetics were investigated using this sensitive method for analysis of these metabolites. In the dose-response investigation, the concentrations of 4-AMX and 2-2AMX are observed to pass through a maximum at 0.10 mg/g. In the case of 2-AMK, the adduct concentration is almost the same at dosages in the range of 0.030 to 0.10 mg/g. For toxicokinetics, the concentration of the metabolites in the Hb reaches a maximum in the 3-day sample after administration of MX or MK. Further elimination of the metabo

  10. Identification of Bound Nitro Musk-Protein Adduct in Fish Liver By Gas Chromatography-Mass Sectrometry: Biotransformation, Dose-Response and Toxicokinetics of Nitro Musk Metabolites Protein Adducts in Trout Liver as Biomarker of Exposure

    Science.gov (United States)

    Ubiquitous occurrences of synthetic nitro musks are evident in the literature. The In vivo analysis of musk xylene (MX) and musk ketone (MK) - protein adducts in trout liver have been performed by gas chromatography-mass spectrometry using selected ion monitoring (GC-SIM-MS). Bio...

  11. Xylene isomerization

    KAUST Repository

    Bilaus, Rakan Sulaiman

    2016-06-23

    A process for producing xylenes, in particular para-xylene that is less energy intensive than conventional processes is provided. In an embodiment the process comprises contacting a feed mixture in an isomenzation zone with a catalyst at isomenzation conditions and producing an isomerized product comprising a higher proportion of p-xylene than in the feed mixture, wherein the catalyst comprises an acidic sulfonated catalytic membrane. Xylene isomenzation can also be coupled with a p-xylene extraction process, where the raffinate (p-xylene deprived stream) from the extraction process is fed to an isomenzation reactor to produce p-xylene. In an embodiment, the process can comprise: a) providing a feed stream comprising a mixture of xylene isomers including p-xylene; b) extracting p-xylene from the feed stream using a separator to separate the feed stream into a p-xylene rich stream and a p-xylene deprived stream; and c) delivering the p-xylene deprived stream to an isomenzation unit, the isomenzation unit including an acidic sulfonated catalytic membrane, and using the isomenzation unit to produce an isomerized product comprising a higher proportion of p-xylene than in the p-xylene deprived stream delivered to the isomenzation unit. In any one or more aspects, the isomenzation unit can be operated at a temperature in the range of less than 350°, for example about 20°C to about 200°C.

  12. Synthetic musk fragrances in Lake Michigan.

    Science.gov (United States)

    Peck, Aaron M; Hornbuckle, Keri C

    2004-01-15

    Synthetic musk fragrances are added to a wide variety of personal care and household products and are present in treated wastewater effluent. Here we report for the first time ambient air and water measurements of six polycyclic musks (AHTN, HHCB, ATII, ADBI, AHMI, and DPMI) and two nitro musks (musk xylene and musk ketone) in North America. The compounds were measured in the air and water of Lake Michigan and in the air of urban Milwaukee, WI. All of the compounds except DPMI were detected. HHCB and AHTN were found in the highest concentrations in all samples. Airborne concentrations of HHCB and AHTN average 4.6 and 2.9 ng/m3, respectively, in Milwaukee and 1.1 and 0.49 ng/m3 over the lake. The average water concentration of HHCB and AHTN in Lake Michigan was 4.7 and 1.0 ng/L, respectively. A lake-wide annual mass budget shows that wastewater treatment plant discharge is the major source (3470 kg/yr) of the synthetic musks while atmospheric deposition contributes less than 1%. Volatilization and outflow through the Straits of Mackinac are major loss mechanisms (2085 and 516 kg/yr for volatilization and outflow, respectively). Concentrations of HHCB are about one-half the predicted steady-state water concentrations in Lake Michigan.

  13. Xylene isomerization

    KAUST Repository

    Bilaus, Rakan Sulaiman; Pinnau, Ingo

    2016-01-01

    at isomenzation conditions and producing an isomerized product comprising a higher proportion of p-xylene than in the feed mixture, wherein the catalyst comprises an acidic sulfonated catalytic membrane. Xylene isomenzation can also be coupled with a p

  14. FORMATION OF NITRO MUSK ADDUCTS OF RAINBOW TROUT HEMOGLOBIN FOR POTENTIAL USE AS BIOMARKERS OF EXPOSURE

    Science.gov (United States)

    The high use of nitro musk xylene (MX) and musk ketone (MK) as fragrances, and their persistence and bioaccumulation potential make them ubiquitous environmental contaminants. The 4-amino-MX (AMX) and 2-amino-MK (AMK) metabolites have been detected in trout fish hemoglobin (Hb) s...

  15. Chemical Mass Shifts in a Digital Linear Ion Trap as Analytical Identity of o-, m-, and p-Xylene.

    Science.gov (United States)

    Sun, Lulu; Xue, Bing; Huang, Zhengxu; Cheng, Ping; Ma, Li; Ding, Li; Zhou, Zhen

    2018-07-01

    Chemical mass shifts between isomeric ions of o-, m-, and p-xylene were measured using a digital linear ion trap, and the directions and values of the shifts were found to be correlated to the collision cross sections of the isomers. Both forward and reverse scans were used and the chemical shifts for each pair of isomers in scans of opposite directions were in opposite signs. Using different voltage settings (namely the voltage dividing ratio-VDR) of the ion trap allows adding high order field components in the quadrupole field and results in larger chemical mass shifts. The differential chemical mass shift which combined the shifts from forward and reverse scans doubled the amount of chemical shift, e.g., 0.077 Th between o- and p-xylene, enough for identification of the type of isomer without using an additional ion mobility spectrometer. The feature of equal and opposite chemical mass shifts also allowed to null out the chemical mass shift by calculating the mean m/z value between the two opposite scans and remove or reduce the mass error caused by chemical mass shift. Graphical Abstract ᅟ.

  16. Chemical Mass Shifts in a Digital Linear Ion Trap as Analytical Identity of o-, m-, and p-Xylene

    Science.gov (United States)

    Sun, Lulu; Xue, Bing; Huang, Zhengxu; Cheng, Ping; Ma, Li; Ding, Li; Zhou, Zhen

    2018-04-01

    Chemical mass shifts between isomeric ions of o-, m-, and p-xylene were measured using a digital linear ion trap, and the directions and values of the shifts were found to be correlated to the collision cross sections of the isomers. Both forward and reverse scans were used and the chemical shifts for each pair of isomers in scans of opposite directions were in opposite signs. Using different voltage settings (namely the voltage dividing ratio-VDR) of the ion trap allows adding high order field components in the quadrupole field and results in larger chemical mass shifts. The differential chemical mass shift which combined the shifts from forward and reverse scans doubled the amount of chemical shift, e.g., 0.077 Th between o- and p-xylene, enough for identification of the type of isomer without using an additional ion mobility spectrometer. The feature of equal and opposite chemical mass shifts also allowed to null out the chemical mass shift by calculating the mean m/z value between the two opposite scans and remove or reduce the mass error caused by chemical mass shift. [Figure not available: see fulltext.

  17. Health Risk Assessment of Xylene through Microenvironment Monitoring Data: A Case Study of the Petro-Chemical Industries, Thailand

    Directory of Open Access Journals (Sweden)

    Pensri Watchalayann

    2009-01-01

    Full Text Available In the absence of environmental health epidemiology, risk managers, policy makers and health-care authorities usually rely on estimates of human exposure level of proximity to hazardous waste site or regional ambient air quality data. Based on ambient concentrations without considering time-activity patterns, the estimation of personal exposure may be overor underestimated. Twelve villages surrounding the petro-chemical industries located in the eastern region of Thailand were randomly selected to be a representative study area. In each village, air samples were collected at thirty-one microenvironments including indoor and outdoor of a household and workplace. The time-activity patterns of the commuters were also recorded. The ambient xylene concentrations were determined by thermal desorption gas chromatograhy/mass spectrometry. The indoor samples were determined by gas chromatography flame ionization detector. Commuters living in the vicinity of the industrial areas spent most of the time indoor (93.2%, especially at home (66.8%. Individuals spent a significant fraction of the day indoors. The concentrations of xylene ranged from less than 1 μg/m3 to 291.3 μg/m3. The highest level was found at the auto repair shop (291.3 μg/m3. Given micro-environmental concentrations and activity times, the average concentrations of xylene to which commuters may be exposed daily ranged from 90.62 to 134.75 μg/m3. The long term exposure level via inhalation was found to be very low. Collectively, no hazard was indicated by the hazard quotient and the results were found to be similar in all villages.

  18. Temperature effect on physical and chemical properties of secondary organic aerosol from m-xylene photooxidation

    Directory of Open Access Journals (Sweden)

    D. R. Cocker III

    2010-04-01

    Full Text Available The chemical and physical differences of secondary organic aerosol (SOA formed at select isothermal temperatures (278 K, 300 K, and 313 K are explored with respect to density, particle volatility, particle hygroscopicity, and elemental chemical composition. A transition point in SOA density, volatility, hygroscopicity and elemental composition is observed near 290–292 K as SOA within an environmental chamber is heated from 278 K to 313 K, indicating the presence of a thermally labile compound. No such transition points are observed for SOA produced at 313 K or 300 K and subsequently cooled to 278 K. The SOA formed at the lowest temperatures (278 K is more than double the SOA formed at 313 K. SOA formed at 278 K is less hydrophilic and oxygenated while more volatile and dense than SOA formed at 300 K or 313 K. The properties of SOA formed at 300 K and 313 K when reduced to 278 K did not match the properties of SOA initially formed at 278 K. This study demonstrates that it is insufficient to utilize the enthalpy of vaporization when predicting SOA temperature dependence.

  19. Synthetic musk fragrances in urban and rural air of Iowa and the Great Lakes

    Science.gov (United States)

    Peck, Aaron M.; Hornbuckle, Keri C.

    Synthetic musk fragrances are semivolatile organic compounds used to scent a variety of household and personal care products. In this study, six polycyclic musk fragrances (HHCB, AHTN, ATII, AHMI, ADBI, and DPMI) and two nitro musk fragrances (musk xylene and musk ketone) were evaluated in 181 air samples collected at urban, suburban, and rural sites in Iowa and the Great Lakes. This is the largest reported study of the compounds in ambient air and reveals the ubiquitous nature of these environmental contaminants. HHCB and AHTN were detected most frequently and at the highest concentrations at all sites. Synthetic musk fragrance concentrations were highest in urban locations, including Milwaukee, WI (previously reported) and an urban location in Cedar Rapids, IA. Urban concentrations of HHCB and AHTN are on the order of 1-5 ng m -3 and background terrestrial concentrations are about an order of magnitude less. In rural Iowa, the concentrations and frequency of detection of the synthetic musk fragrances are comparable to (and often greater than) gas-phase pesticide concentrations. The concentrations measured at the suburban location in Iowa City, IA and over the Lakes Erie, Ontario, and Michigan were generally intermediate of those measured at the rural and urban locations. Concentrations of HHCB and AHTN were correlated with temperature at the sampling sites in Iowa.

  20. Elon Musk, een visionaire ondernemer

    NARCIS (Netherlands)

    ir.ing. Ruud Thelosen

    2016-01-01

    Deze biografie van de nog vrij jonge ondernemer en maatschappijvernieuwer Elon Musk is een bijzonder boek over een bijzondere man. Musk beschikt over uitzonderlijke gaven en heeft deze ook sterk ontwikkeld. Daarnaast realiseert hij zijn diepste dromen, die misschien wel leiden tot een Marskolonie.

  1. LEVELS OF SYNTHETIC MUSKS COMPOUNDS IN AQUATIC ...

    Science.gov (United States)

    Synthetic musk compounds are consumer chemicals manufactured as fragrance materials Due to their high worldwide usage and release, they frequently occur in the aquatic and marine environments. The U.S. EPA (ORD, Las Vegas) developed surface-water monitoring methodology and conducted a one-year monthly monitoring of synthetic musks in water and biota from Lake Mead (Nevada) as well as from combined sewage effluent streams feeding Lake Mead. Presented are the overview of the chemistry, the monitoring methodology, and the significance of synthetic musk compounds in the aquatic environment. The research focused on in the subtasks is the development and application of state-of the-art technologies to meet the needs of the public, Office of Water, and ORD in the area of Water Quality. Located In the subtasks are the various research projects being performed in support of this Task and more in-depth coverage of each project. Briefly, each project's objective is stated below.Subtask 1: To integrate state-of-the-art technologies (polar organic chemical integrative samplers, advanced solid-phase extraction methodologies with liquid chromatography/electrospray/mass spectrometry) and apply them to studying the sources and fate of a select list of PPCPs. Application and improvement of analytical methodologies that can detect non-volatile, polar, water-soluble pharmaceuticals in source waters at levels that could be environmentally significant (at concentrations less than p

  2. Inputs and distributions of synthetic musk fragrances in an estuarine and coastal environment; a case study

    Energy Technology Data Exchange (ETDEWEB)

    Sumner, Nicola R. [School of Earth, Ocean and Environmental Science, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth PL1 3DH (United Kingdom); Guitart, Carlos, E-mail: guitart.carlos@gmail.co [Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth PL1 3DH (United Kingdom); Fuentes, Gustavo [Instituto Universitario de Tecnologia del Mar (IUTEMAR), Fundacion La Salle de Ciencias Naturales, Margarita Island (Venezuela, Bolivarian Republic of); Readman, James W. [Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth PL1 3DH (United Kingdom)

    2010-01-15

    Synthetic musks are ubiquitous contaminants in the environment. Compartmental distributions (dissolved, suspended particle associated and sedimentary) of the compounds throughout an axial estuarine transect and in coastal waters are reported. High concentrations of Galaxolide (HHCB) and Tonalide (AHTN) (987-2098 ng/L and 55-159 ng/L, respectively) were encountered in final effluent samples from sewage treatment plants (STPs) discharging into the Tamar and Plym Estuaries (UK), with lower concentrations of Celestolide (ADBI) (4-13 ng/L), Phantolide (AHMI) (6-9 ng/L), musk xylene (MX) (4-7 ng/L) and musk ketone (MK) (18-30 ng/L). Rapid dilution from the outfalls is demonstrated with resulting concentrations of HHCB spanning from 5 to 30 ng/L and those for AHTN from 3 to 15 ng/L. The other musks were generally not detected in the estuarine and coastal waters. The suspended particulate matter (SPM) and sedimentary profiles and compositions (HHCB:AHTN ratios) generally reflect the distribution in the water column with highest concentrations adjacent to sewage outfalls. - Synthetic musks were determined in coastal environmental compartments along an estuarine transect indicating their ubiquitous occurrence in transitional waters.

  3. Inputs and distributions of synthetic musk fragrances in an estuarine and coastal environment; a case study

    International Nuclear Information System (INIS)

    Sumner, Nicola R.; Guitart, Carlos; Fuentes, Gustavo; Readman, James W.

    2010-01-01

    Synthetic musks are ubiquitous contaminants in the environment. Compartmental distributions (dissolved, suspended particle associated and sedimentary) of the compounds throughout an axial estuarine transect and in coastal waters are reported. High concentrations of Galaxolide (HHCB) and Tonalide (AHTN) (987-2098 ng/L and 55-159 ng/L, respectively) were encountered in final effluent samples from sewage treatment plants (STPs) discharging into the Tamar and Plym Estuaries (UK), with lower concentrations of Celestolide (ADBI) (4-13 ng/L), Phantolide (AHMI) (6-9 ng/L), musk xylene (MX) (4-7 ng/L) and musk ketone (MK) (18-30 ng/L). Rapid dilution from the outfalls is demonstrated with resulting concentrations of HHCB spanning from 5 to 30 ng/L and those for AHTN from 3 to 15 ng/L. The other musks were generally not detected in the estuarine and coastal waters. The suspended particulate matter (SPM) and sedimentary profiles and compositions (HHCB:AHTN ratios) generally reflect the distribution in the water column with highest concentrations adjacent to sewage outfalls. - Synthetic musks were determined in coastal environmental compartments along an estuarine transect indicating their ubiquitous occurrence in transitional waters.

  4. Direct atmospheric pressure chemical ionization-tandem mass spectrometry for the continuous real-time trace analysis of benzene, toluene, ethylbenzene, and xylenes in ambient air.

    Science.gov (United States)

    Badjagbo, Koffi; Picard, Pierre; Moore, Serge; Sauvé, Sébastien

    2009-05-01

    Real-time monitoring of benzene, toluene, ethylbenzene, and xylenes (BTEX) in ambient air is essential for the early warning detection associated with the release of these hazardous chemicals and in estimating the potential exposure risks to humans and the environment. We have developed a tandem mass spectrometry (MS/MS) method for continuous real-time determination of ambient trace levels of BTEX. The technique is based on the sampling of air via an atmospheric pressure inlet directly into the atmospheric pressure chemical ionization (APCI) source. The method is linear over four orders of magnitude, with correlation coefficients greater than 0.996. Low limits of detection in the range 1-2 microg/m(3) are achieved for BTEX. The reliability of the method was confirmed through the evaluation of quality parameters such as repeatability and reproducibility (relative standard deviation below 8% and 10%, respectively) and accuracy (over 95%). The applicability of this method to real-world samples was evaluated through measurements of BTEX levels in real ambient air samples and results were compared with a reference GC-FID method. This direct APCI-MS/MS method is suitable for real-time analysis of BTEX in ambient air during regulation surveys as well as for the monitoring of industrial processes or emergency situations.

  5. Synthetic Musk Fragrances in a Conventional Drinking Water Treatment Plant with Lime Softening.

    Science.gov (United States)

    Wombacher, William D; Hornbuckle, Keri C

    2009-11-01

    Synthetic musk fragrances are common personal care product additives and wastewater contaminants that are routinely detected in the environment. This study examines the presence eight synthetic musk fragrances (AHTN, HHCB, ATII, ADBI, AHMI, musk xylene, and musk ketone) in source water and the removal of these compounds as they flow through a Midwestern conventional drinking water plant with lime softening. The compounds were measured in water, waste sludge, and air throughout the plant. HHCB and AHTN were detected in 100% of the samples and at the highest concentrations. A mass balance on HHCB and AHTN was performed under warm and cold weather conditions. The total removal efficiency for HHCB and AHTN, which averaged between 67% to 89%, is dominated by adsorption to water softener sludge and its consequent removal by sludge wasting and media filtration. Volatilization, chlorine disinfection, and the disposal of backwash water play a minor role in the removal of both compounds. As a result of inefficient overall removal, HHCB and AHTN are a constant presence at low levels in finished drinking water.

  6. Assessing human variability in kinetics for exposures to multiple environmental chemicals: a physiologically based pharmacokinetic modeling case study with dichloromethane, benzene, toluene, ethylbenzene, and m-xylene.

    Science.gov (United States)

    Valcke, Mathieu; Haddad, Sami

    2015-01-01

    The objective of this study was to compare the magnitude of interindividual variability in internal dose for inhalation exposure to single versus multiple chemicals. Physiologically based pharmacokinetic models for adults (AD), neonates (NEO), toddlers (TODD), and pregnant women (PW) were used to simulate inhalation exposure to "low" (RfC-like) or "high" (AEGL-like) air concentrations of benzene (Bz) or dichloromethane (DCM), along with various levels of toluene alone or toluene with ethylbenzene and xylene. Monte Carlo simulations were performed and distributions of relevant internal dose metrics of either Bz or DCM were computed. Area under the blood concentration of parent compound versus time curve (AUC)-based variability in AD, TODD, and PW rose for Bz when concomitant "low" exposure to mixtures of increasing complexities occurred (coefficient of variation (CV) = 16-24%, vs. 12-15% for Bz alone), but remained unchanged considering DCM. Conversely, AUC-based CV in NEO fell (15 to 5% for Bz; 12 to 6% for DCM). Comparable trends were observed considering production of metabolites (AMET), except for NEO's CYP2E1-mediated metabolites of Bz, where an increased CV was observed (20 to 71%). For "high" exposure scenarios, Cmax-based variability of Bz and DCM remained unchanged in AD and PW, but decreased in NEO (CV= 11-16% to 2-6%) and TODD (CV= 12-13% to 7-9%). Conversely, AMET-based variability for both substrates rose in every subpopulation. This study analyzed for the first time the impact of multiple exposures on interindividual variability in toxicokinetics. Evidence indicates that this impact depends upon chemical concentrations and biochemical properties, as well as the subpopulation and internal dose metrics considered.

  7. All rights reserved Competitive Adsorption of Xylene and Toluene on ...

    African Journals Online (AJOL)

    ADOWIE PERE

    2018-03-23

    Mar 23, 2018 ... However, when the assay was performed under agitation, it yielded higher ... petrochemical industries for removal of hydrocarbons (m- xylene and toluene) from their waste ... a result of chemical alteration of the volcanic ash.

  8. Scented traces--Dermal exposure of synthetic musk fragrances in personal care products and environmental input assessment.

    Science.gov (United States)

    Homem, Vera; Silva, Eduardo; Alves, Arminda; Santos, Lúcia

    2015-11-01

    Synthetic musks are organic compounds used as fragrance and fixative additives in several personal care products. Until now, little is known about their occurrence and distribution in these household commodities. However, this information is essential to perform a human dermal exposure assessment. Therefore, this study gives an overview on the levels of 12 synthetic musks in 140 personal care products from 7 different categories (body and hair wash, toilet soaps, shaving products, dentifrice products, deodorants/antiperspirants, moisturizers and perfumes). They were analysed by QuEChERS extraction followed by gas chromatography-mass spectrometry. Detection limits were found between 0.01ngg(-1) (galaxolide) and 5.00ngg(-1) (musk xylene). Higher average concentrations of total synthetic musks were detected in perfumes (5245.05μgg(-1)) and shampoos (487.67μgg(-1)) for adults. Galaxolide, exaltolide and cashmeran were the most detected compounds. Combining these results with the daily usage amounts, an average daily dermal exposure of 75.69μgkgbw(-1)day(-1) for adults and 15.54μgkgbw(-1)day(-1) for babies/children was achieved. The main contributors for adult and babies/children dermal exposure were perfumes and lotions, respectively. About 40% of the adult daily dermal exposure is related to exaltolide, 30% galaxolide, and 15% tonalide, while for babies/children 96% occurs due to exaltolide. An estimate of the amount of musks discharged "down-the-drain" into the wastewater treatment systems through the use of toiletries was also performed. An average emission per capita of 6.7mgday(-1) was determined and galaxolide and exaltolide were the predominant musks in the effluents. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Removal of two polycyclic musks in sewage treatment plants: Freely dissolved and total concentrations

    NARCIS (Netherlands)

    Artola-Garicano, E.; Borkent, I.; Hermens, J.L.M.; Vaes, W.H.J.

    2003-01-01

    In the current study, the removal of slowly degradable hydrophobic chemicals in sewage treatment plants (STPs) has been evaluated with emphasis on the combination of free and total concentration data. Free and total concentrations of two polycyclic musks were determined in each compartment of four

  10. Biomonitoring of chemicals in biota of two wetland protected areas exposed to different levels of environmental impact: results of the "PREVIENI" project.

    Science.gov (United States)

    Guerranti, Cristiana; Perra, Guido; Alessi, Eva; Baroni, Davide; Caserta, Dante; Caserta, Donatella; De Sanctis, Augusto; Fanello, Emiliano Leonida; La Rocca, Cinzia; Mariottini, Michela; Renzi, Monia; Tait, Sabrina; Zaghi, Carlo; Mantovani, Alberto; Focardi, Silvano Ettore

    2017-08-18

    The PREVIENI project (funded by the Ministry of Environment) investigated the exposure to endocrine disrupters in samples of human population and environmental biota in Italy. The environmental biomonitoring considered two Italian WWF Oasis, with the aim to compare the presence and effects of endocrine disruptors in organisms from two protected natural areas, respectively, upstream and downstream a chemical emission site. Chemical analysis of pollutants' tissue levels was made on tissues from earthworm, barbell, trout, and coot, selected as bioindicator organisms. The contaminants considered were as follows: the perfluorinated compounds perfuoroctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), polychlorinated biphenyls (PCBs 58 congeners), polybrominated diphenyl ethers (PBDEs, 13 congeners), polycyclic aromatic hydrocarbons (PAHs, 16 compounds), toxic trace elements, the phthalate di-2-ethylexyl phthalate (DEHP) and its primary metabolite, bisphenol A, synthetic musk compounds (musk xylene, musk ketone, tonalide, and galaxolide), and p-nonylphenol. The analyses showed low concentrations of most pollutants in all species from both areas, compared to available literature; noticeable exceptions were the increases of DEHP's primary metabolite, PBDE, PAHs, Hg, and Pb in barbells, and of PCB and Cd in earthworms from the downstream area. The results showed the presence of endocrine disruptors, including those considered as "non-persistent," in bioindicators from protected areas, albeit at low levels. The results provide a contribution to the evaluation of reference values in biota from Mediterranean Europe and support the relevance of monitoring exposure to pollutants, in particular for freshwater environment, also in protected areas.

  11. Membrane Materials and Technology for Xylene Isomers Separation and Isomerization via Pervaporation

    KAUST Repository

    Bilaus, Rakan

    2014-11-01

    P-xylene is one of the highly influential commodities in the petrochemical industry. It is used to make 90% of the world’s third largest plastic production, polyethylene terephthalate (PET). With a continuously increasing demand, the current technology’s high energy intensity has become a growing concern. Membrane separation technology is a potential low-energy alternative. Polymeric membranes were investigated in a pervaporation experiment to separate xylene isomers. Polymers of intrinsic microporosity (PIMs) as well as polyimides (PIM-PI), including thermally cross-linked PIM-1, PIM-6FDA-OH and thermally-rearranged PIM-6FDA-OH were investigated as potential candidates. Although they exhibited extremely high permeability to xylenes, selectivity towards p-xylene was poor. This was attributed to the polymers low chemical resistance which was apparent in their strong tendency to swell in xylenes. Consequently, a perfluoro-polymer, Teflon AF 2400, with a high chemical resistance was tested, which resulted in a slightly improved selectivity. A super acid sulfonated perfluoro-polymer (Nafion-H) was used as reactive membrane for xylenes isomerization. The membrane exhibited high catalytic activity, resulting in 19.5% p-xylene yield at 75ᵒC compared to 20% p-xylene yield at 450ᵒC in commercial fixed bed reactors. Nafion-H membrane outperforms the commercial technology with significant energy savings.

  12. Problem Definition Studies on Potential Environmental Pollutants. 4. Physical, Chemical, Toxicological, and Biological Properties of Benzene; Toluene; Xylenes; and para-Chlorophenyl Methyl Sulfide, Sulfoxide, and Sulfone

    Science.gov (United States)

    1976-06-01

    microorganisms. The presence of nitro, amino or sulfonic acid groups or halogens on the ring will almost always render benzene and related compounds...benzoquinone --- muconic acid Their later experiments with tea and grape leaf homogenates support this * conclusion. 12 2 Tkhelidze 1 2 3 showed that grape ...of such chemicals as phenol, aniline, cumene, adipic acid , diphenyl, and ethyl- * benzene, each of which is a starting material for other products

  13. Health Hazards of Xylene: A Literature Review

    OpenAIRE

    T. Rajan, Sharada; Malathi, N.

    2014-01-01

    Xylene, an aromatic hydrocarbon is widely used in industry and medical laboratory as a solvent. It is a flammable liquid that requires utmost care during its usage. On exposure the vapours are rapidly absorbed through the lungs and the slowly through the skin. Prolonged exposure to xylene leads to significant amount of solvent accumulation in the adipose and muscle tissue. This article reviews the various acute and chronic health effects of xylene through various routes of exposure.

  14. Enhanced xylene removal by photocatalytic oxidation using fiber-illuminated honeycomb reactor at ppb level

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yi-Ting [Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Yu, Yi-Hui [Department of Civil Engineering, National Taiwan University, Taipei 106, Taiwan (China); Nguyen, Van-Huy [Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 10617, Taiwan (China); Lu, Kung-Te [Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Wu, Jeffrey Chi-Sheng, E-mail: cswu@ntu.edu.tw [Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Chang, Luh-Maan [Department of Civil Engineering, National Taiwan University, Taipei 106, Taiwan (China); Kuo, Chi-Wen [Taiwan Semiconductor Manufacturing Company, Hsinchu 30078, Taiwan (China)

    2013-11-15

    Graphical abstract: We have designed a fiber-illuminated honeycomb reactor (FIHR) in which the removal efficiency of m-xylene is significantly enhanced to 96.5% as compared to 22.0% for UV irradiation only. The results indicate that photocatalysts not only play the role to substantially oxidize m-xylene, but also alter the chemical properties of xylene under UV illumination. -- Highlights: • The combination of optical fiber and honeycomb significantly enhanced the performance of VOCs photodegradation. • The removal efficiency of m-xylene is enhanced to 96.5% as compared to 22.0% for UV irradiation alone. • Fiber-illuminated honeycomb reactor is the first step toward an industrial-scale technology on the removal of xylene. -- Abstract: The removal of volatile organic compounds (VOCs) at ppb level is one of the most critical challenges in clean rooms for the semiconductor industry. Photocatalytic oxidation is an innovative and promising technology for ppb-level VOCs degradation. We have designed a fiber-illuminated honeycomb reactor (FIHR) in which the removal efficiency of m-xylene is significantly enhanced to 96.5% as compared to 22.0% for UV irradiation only. The results indicate that photocatalysts not only play the role to substantially oxidize m-xylene, but also alter the chemical properties of xylene under UV illumination. Using the FIHR with Mn-TiO{sub 2} photocatalyst not only increased the m-xylene removal efficiency, but also increased the CO{sub 2} selectivity. Interestingly, Mn-TiO{sub 2} in FIHR also showed a very good reusability, 93% removal efficiency was still achieved in 72-h in reaction. Thus, the FIHR gave very high removal efficiency for xylene at ppb level under room temperature. The FIHR has great potential application in the clean room for the air purification system in the future.

  15. Enhanced xylene removal by photocatalytic oxidation using fiber-illuminated honeycomb reactor at ppb level

    International Nuclear Information System (INIS)

    Wu, Yi-Ting; Yu, Yi-Hui; Nguyen, Van-Huy; Lu, Kung-Te; Wu, Jeffrey Chi-Sheng; Chang, Luh-Maan; Kuo, Chi-Wen

    2013-01-01

    Graphical abstract: We have designed a fiber-illuminated honeycomb reactor (FIHR) in which the removal efficiency of m-xylene is significantly enhanced to 96.5% as compared to 22.0% for UV irradiation only. The results indicate that photocatalysts not only play the role to substantially oxidize m-xylene, but also alter the chemical properties of xylene under UV illumination. -- Highlights: • The combination of optical fiber and honeycomb significantly enhanced the performance of VOCs photodegradation. • The removal efficiency of m-xylene is enhanced to 96.5% as compared to 22.0% for UV irradiation alone. • Fiber-illuminated honeycomb reactor is the first step toward an industrial-scale technology on the removal of xylene. -- Abstract: The removal of volatile organic compounds (VOCs) at ppb level is one of the most critical challenges in clean rooms for the semiconductor industry. Photocatalytic oxidation is an innovative and promising technology for ppb-level VOCs degradation. We have designed a fiber-illuminated honeycomb reactor (FIHR) in which the removal efficiency of m-xylene is significantly enhanced to 96.5% as compared to 22.0% for UV irradiation only. The results indicate that photocatalysts not only play the role to substantially oxidize m-xylene, but also alter the chemical properties of xylene under UV illumination. Using the FIHR with Mn-TiO 2 photocatalyst not only increased the m-xylene removal efficiency, but also increased the CO 2 selectivity. Interestingly, Mn-TiO 2 in FIHR also showed a very good reusability, 93% removal efficiency was still achieved in 72-h in reaction. Thus, the FIHR gave very high removal efficiency for xylene at ppb level under room temperature. The FIHR has great potential application in the clean room for the air purification system in the future

  16. Metal-Organic Frameworks for Resonant-Gravimetric Detection of Trace-Level Xylene Molecules.

    Science.gov (United States)

    Xu, Tao; Xu, Pengcheng; Zheng, Dan; Yu, Haitao; Li, Xinxin

    2016-12-20

    As one of typical VOCs, xylene is seriously harmful to human health. Nowadays, however, there is really lack of portable sensing method to directly detect environmental xylene that has chemical inertness. Especially when the concentration of xylene is lower than the human olfactory threshold of 470 ppb, people are indeed hard to be aware of and avoid this harmful vapor. Herein the metal-organic framework (MOF) of HKUST-1 is first explored for sensing to the nonpolar molecule of p-xylene. And the sensing mechanism is identified that is via host-guest interaction of MOF with xylene molecule. By loading MOFs on mass-gravimetric resonant-cantilevers, sensing experiments for four MOFs of MOF-5, HKUST-1, ZIF-8, and MOF-177 approve that HKUST-1 has the highest sensitivity to p-xylene. The resonant-gravimetric sensing experiments with our HKUST-1 based sensors have demonstrated that trace-level p-xylene of 400 ppb can be detected that is lower than the human olfactory threshold of 470 ppb. We analyze that the specificity of HKUST-1 to xylene comes from Cu 2+ -induced moderate Lewis acidity and the "like dissolves like" interaction of the benzene ring. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) is used to elucidate the adsorbing/sensing mechanism of HKUST-1 to p-xylene, where p-xylene adsorbing induced blue-shift phenomenon is observed that confirms the sensing mechanism. Our study also indicates that the sensor shows good selectivity to various kinds of common interfering gases. And the long-term repeatability and stability of the sensing material are also approved for the usage/storage period of two months. This research approves that the MOF materials exhibit potential usages for high performance chemical sensors applications.

  17. Infantile Onset Myasthenia Gravis with MuSK Antibodies

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2006-08-01

    Full Text Available A late infantile case of myasthenia gravis (MG with anti-muscle-specific receptor tyrosine kinase (MuSK high antibody (Ab titer is reported from Kyushu University, Fukuoka; and Nagasaki University, Japan.

  18. Elon Musk – riskanter Milliardenpoker um Tesla & Co.

    OpenAIRE

    Lipp, Reto

    2017-01-01

    Interview von Reto Lipp mit Peter Leibfried (SRF ECO): Von seinen Fans wird er wie ein Rockstar gefeiert. Ob Tesla, Solar City oder SpaceX, Elon Musk will die Welt revolutionieren. Doch seine Visionen verschlingen Unsummen. Bisher ist es ihm stets gelungen, neue Gelder zu mobilisieren und bei Bedarf Millionenbeträge zwischen seinen Unternehmen hin und her zu schieben. Doch das Firmenimperium lebt von riesigen Erwartungen der Investoren. Kann Elon Musk sie nicht einlösen, droht der Kollaps.

  19. SOA formation from photooxidation of naphthalene and methylnaphthalenes with m-xylene and surrogate mixtures

    Science.gov (United States)

    Chen, Chia-Li; Li, Lijie; Tang, Ping; Cocker, David R.

    2018-05-01

    SOA formation is not well predicted in current models in urban area. The interaction among multiple anthropogenic volatile organic compounds is essential for the SOA formation in the complex urban atmosphere. Secondary organic aerosol (SOA) from the photooxidation of naphthalene, 1-methylnaphthalene, and 2-methylnaphthalene as well as individual polycyclic aromatic hydrocarbons (PAHs) mixed with m-xylene or an atmospheric surrogate mixture was explored in the UCR CE-CERT environmental chamber under urban relevant low NOx and extremely low NOx (H2O2) conditions. Addition of m-xylene suppressed SOA formation from the individual PAH precursor. A similar suppression effect on SOA formation was observed during the surrogate mixture photooxidation suggesting the importance of gas-phase chemical reactivity to SOA formation. The SOA growth rate for different PAH-m-xylene mixtures was strongly correlated with initial [HO2]/[RO2] ratio but negatively correlated with initial m-xylene/NO ratio. Decreasing SOA formation was observed for increasing m-xylene/PAHs ratios and increasing initial m-xylene/NO ratio. The SOA chemical composition characteristics such as f44 versus f43, H/C ratio, O/C ratio, and the oxidation state of the carbon OSbarc were consistent with a continuously aging with the SOA exhibiting characteristics of both individual precursors. SOA formation from PAHs was also suppressed within an atmospheric surrogate mixture compared to the SOA formed from individual PAHs, indicating that atmospheric reactivity directly influences SOA formation from PAHs.

  20. Concentrations and assessment of exposure to siloxanes and synthetic musks in personal care products from China

    International Nuclear Information System (INIS)

    Lu Yan; Yuan Tao; Wang Wenhua; Kannan, Kurunthachalam

    2011-01-01

    We investigated the concentrations and profiles of 15 siloxanes (four cyclic siloxanes, D 4 -D 7 ; 11 linear siloxanes, L 4 -L 14 ), four synthetic musks (two polycyclic musks, HHCB and AHTN; two nitro musks, MX and MK), and HHCB-lactone, in 158 personal care products marketed in China. Siloxanes were detected in 88% of the samples analyzed, at concentrations as high as 52.6 mg g -1 ; Linear siloxanes were the predominant compounds. Among synthetic musks, more than 80% of the samples contained at least one of these compounds, and their total concentrations were as high as 1.02 mg g -1 . HHCB was the predominant musk in all of the samples analyzed, on average, accounting for 52% of the total musk concentrations. Based on the median concentrations of siloxanes and musks and the average daily usage amounts of consumer products, dermal exposure rates in adults were calculated to be 3.69 and 3.38 mg d -1 for siloxanes and musks, respectively. - Highlights: → Siloxanes and synthetic musks are determined in personal care products. → Highest siloxane concentration was 52.6 mg g -1 . → Highest musk concentration was 1.02 mg g -1 . → Daily dermal exposure rates of siloxanes and musks were in mg levels. → Dermal exposure is a major pathway of human exposure to siloxanes and musks. - Dermal application of several personal care products is a major source of human exposure to cyclic and linear siloxanes.

  1. Mixture effects of benzene, toluene, ethylbenzene, and xylenes (BTEX) on lung carcinoma cells via a hanging drop air exposure system.

    Science.gov (United States)

    Liu, Faye F; Escher, Beate I; Were, Stephen; Duffy, Lesley; Ng, Jack C

    2014-06-16

    A recently developed hanging drop air exposure system for toxicity studies of volatile chemicals was applied to evaluate the cell viability of lung carcinoma A549 cells after 1 and 24 h of exposure to benzene, toluene, ethylbenzene, and xylenes (BTEX) as individual compounds and as mixtures of four or six components. The cellular chemical concentrations causing 50% reduction of cell viability (EC50) were calculated using a mass balance model and came to 17, 12, 11, 9, 4, and 4 mmol/kg cell dry weight for benzene, toluene, ethylbenzene, m-xylene, o-xylene, and p-xylene, respectively, after 1 h of exposure. The EC50 decreased by a factor of 4 after 24 h of exposure. All mixture effects were best described by the mixture toxicity model of concentration addition, which is valid for chemicals with the same mode of action. Good agreement with the model predictions was found for benzene, toluene, ethylbenzene, and m-xylene at four different representative fixed concentration ratios after 1 h of exposure, but lower agreement with mixture prediction was obtained after 24 h of exposure. A recreated car exhaust mixture, which involved the contribution of the more toxic p-xylene and o-xylene, yielded an acceptable, but lower quality, prediction as well.

  2. High-temperature rate constant measurements for OH+xylenes

    KAUST Repository

    Elwardani, Ahmed Elsaid; Badra, Jihad; Farooq, Aamir

    2015-01-01

    The overall rate constants for the reactions of hydroxyl (OH) radicals with o-xylene (k 1), m-xylene (k 2), and p-xylene (k 3) were measured behind reflected shock waves over 890-1406K at pressures of 1.3-1.8atm using OH laser absorption near 306

  3. Effects of dietary exposure of polycyclic musk HHCB on the metamorphosis of Xenopus laevis.

    Science.gov (United States)

    Pablos, María Victoria; Jiménez, María Ángeles; San Segundo, Laura; Martini, Federica; Beltrán, Eulalia; Fernández, Carlos

    2016-06-01

    The compound 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-[γ]-2-benzopyrane (HHCB; galaxolide, Chemical Abstracts Service number 1222-05-5) is a synthetic musk used extensively as a fragrance in many consumer products and classified as an emerging pollutant. The ecotoxicological information available for HHCB addresses exposure via water, but this compound is frequently adsorbed into particulate matter. The goal of the present study was to assess the effects of dietary exposure to several environmentally relevant HHCB concentrations adsorbed in food during Xenopus laevis metamorphosis. The authors sought to determine if such exposure to this synthetic musk resulted in histological changes in the thyroid gland in conjunction with changes in development (staging, timing to metamorphosis), body weight, and length. Developmental acceleration on day 14, together with hypertrophy of the thyroid follicular epithelium in tadpoles, suggested a possible agonistic effect of HHCB, which would have been compensated after metamorphosis by regulatory mechanisms to maintain homeostasis. Further research into the potential thyroid-related mechanisms of action of HHCB should be conducted. Environ Toxicol Chem 2016;35:1428-1435. © 2015 SETAC. © 2015 SETAC.

  4. Enhanced xylene removal by photocatalytic oxidation using fiber-illuminated honeycomb reactor at ppb level.

    Science.gov (United States)

    Wu, Yi-Ting; Yu, Yi-Hui; Nguyen, Van-Huy; Lu, Kung-Te; Wu, Jeffrey Chi-Sheng; Chang, Luh-Maan; Kuo, Chi-Wen

    2013-11-15

    The removal of volatile organic compounds (VOCs) at ppb level is one of the most critical challenges in clean rooms for the semiconductor industry. Photocatalytic oxidation is an innovative and promising technology for ppb-level VOCs degradation. We have designed a fiber-illuminated honeycomb reactor (FIHR) in which the removal efficiency of m-xylene is significantly enhanced to 96.5% as compared to 22.0% for UV irradiation only. The results indicate that photocatalysts not only play the role to substantially oxidize m-xylene, but also alter the chemical properties of xylene under UV illumination. Using the FIHR with Mn-TiO2 photocatalyst not only increased the m-xylene removal efficiency, but also increased the CO2 selectivity. Interestingly, Mn-TiO2 in FIHR also showed a very good reusability, 93% removal efficiency was still achieved in 72-h in reaction. Thus, the FIHR gave very high removal efficiency for xylene at ppb level under room temperature. The FIHR has great potential application in the clean room for the air purification system in the future. Copyright © 2013 Elsevier B.V. All rights reserved.

  5. Steroid profile and IRMS analysis of musk administration for doping control.

    Science.gov (United States)

    Wang, Jingzhu; He, Yi; Liu, Xin; Yang, Zhiyong; Yang, Wenning

    2017-11-01

    Musk, the dried secretion of the musk pod (sac) of adult male musk deer, has been used as traditional Chinese Medicine (TCM) in China and south-east Asian countries for thousands of years. Due to the anabolic steroid component in this TCM, musk preparations have been included in the list of medical products containing prohibited substances employed for doping by the State Food and Drug Administration of China. The application of musk pod formulation was claimed to be responsible for some adverse analytical findings (AAFs) in the 2011 FIFA Women's World Cup. Our preliminary study has suggested that musk ingestion did not lead to AAFs of doping control with the single dosage of 100 mg. However, the influences of musk administration in large and multi dosage are still unclear. The aim of this study is to further investigate the influences of musk administration for doping control. Wild and domestic deer musk samples were collected. The concentrations and δ 13 C-values of steroids in musk were analyzed. In an excretion study, 200 and 100 mg of wild and domestic deer musk samples were administrated by 29 subjects, respectively. Fluctuations in steroid profile could be observed, and the ratio of 5α-androstane-3α,17β-diol to 5β-androstane-3α,17β-diol was more sensitive than other parameters. In the IRMS test, the ∆Δδ 13 C-value between endogenous reference compound and etiocholanolone was a sensitive parameter, and AAFs were obtained. It is the first time to confirm with excretion study that musk administration could lead to positive result of doping control. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  6. Concentrations and assessment of exposure to siloxanes and synthetic musks in personal care products from China

    Energy Technology Data Exchange (ETDEWEB)

    Lu Yan [School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Wadsworth Center, New York State Department of Health and Department of Environmental Health Sciences, School of Public Health, State University of New York at Albany, Empire State Plaza, PO Box 509, Albany, NY 12201-0509 (United States); Yuan Tao; Wang Wenhua [School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Kannan, Kurunthachalam, E-mail: kkannan@wadsworth.org [Wadsworth Center, New York State Department of Health and Department of Environmental Health Sciences, School of Public Health, State University of New York at Albany, Empire State Plaza, PO Box 509, Albany, NY 12201-0509 (United States); International Joint Research Center for Persistent Toxic Substances, State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090 (China)

    2011-12-15

    We investigated the concentrations and profiles of 15 siloxanes (four cyclic siloxanes, D{sub 4}-D{sub 7}; 11 linear siloxanes, L{sub 4}-L{sub 14}), four synthetic musks (two polycyclic musks, HHCB and AHTN; two nitro musks, MX and MK), and HHCB-lactone, in 158 personal care products marketed in China. Siloxanes were detected in 88% of the samples analyzed, at concentrations as high as 52.6 mg g{sup -1}; Linear siloxanes were the predominant compounds. Among synthetic musks, more than 80% of the samples contained at least one of these compounds, and their total concentrations were as high as 1.02 mg g{sup -1}. HHCB was the predominant musk in all of the samples analyzed, on average, accounting for 52% of the total musk concentrations. Based on the median concentrations of siloxanes and musks and the average daily usage amounts of consumer products, dermal exposure rates in adults were calculated to be 3.69 and 3.38 mg d{sup -1} for siloxanes and musks, respectively. - Highlights: > Siloxanes and synthetic musks are determined in personal care products. > Highest siloxane concentration was 52.6 mg g{sup -1}. > Highest musk concentration was 1.02 mg g{sup -1}. > Daily dermal exposure rates of siloxanes and musks were in mg levels. > Dermal exposure is a major pathway of human exposure to siloxanes and musks. - Dermal application of several personal care products is a major source of human exposure to cyclic and linear siloxanes.

  7. Comparative Analysis of the Gut Microbiota Composition between Captive and Wild Forest Musk Deer

    Directory of Open Access Journals (Sweden)

    Yimeng Li

    2017-09-01

    Full Text Available The large and complex gut microbiota in animals has profound effects on feed utilization and metabolism. Currently, gastrointestinal diseases due to dysregulated gut microbiota are considered important factors that limit growth of the captive forest musk deer population. Compared with captive forest musk deer, wild forest musk deer have a wider feeding range with no dietary limitations, and their gut microbiota are in a relatively natural state. However, no reports have compared the gut microbiota between wild and captive forest musk deer. To gain insight into the composition of gut microbiota in forest musk deer under different food-source conditions, we employed high-throughput 16S rRNA sequencing technology to investigate differences in the gut microbiota occurring between captive and wild forest musk deer. Both captive and wild forest musk deer showed similar microbiota at the phylum level, which consisted mainly of Firmicutes and Bacteroidetes, although significant differences were found in their relative abundances between both groups. α-Diversity results showed that no significant differences occurred in the microbiota between both groups, while β-diversity results showed that significant differences did occur in their microbiota compositions. In summary, our results provide important information for improving feed preparation for captive forest musk deer and implementing projects where captive forest musk deer are released into the wild.

  8. A novel non-toxic xylene substitute (SBO) for histology.

    Science.gov (United States)

    Kunhua, Wang; Chuming, Fan; Tao, Lai; Yanmei, Yang; Xin, Yang; Xiaoming, Zhang; Xuezhong, Guo; Xun, Lai

    2012-01-01

    Xylene has been generally used as a clearing and deparaffinizing agent in histology. Because of the potential toxic and flammable nature of xylene, its substitutes have been introduced into some laboratories. In this study, we introduced a novel, non-toxic xylene substitute (SBO), which was generated through a mixture of 86% of white oil No.2 and 14% of N-heptane. SBO had a high boiling point (188°C) and flash point (144°C) coupled with a scentless and decreased volatility. To compare the effectiveness of SBO and xylene in histology, a wide range of tissue samples from rats and human beings were processed in parallel in SBO and xylene, subjected to various staining procedures. Similar to the xylene-processed paraffin blocks, the SBO-processed counterparts were easy to section without any evidence of cell shrinkage. Assessment of the SBO-treated sections stained with hematoxylin-eosin revealed a good maintenance of cell morphology and structure, and a clear definition of the cytoplasm and the nucleus. Moreover, comparable good results were achieved between the SBO- and xylene-processed tissues in other histochemical and immunohistochemical stainings. Six-month clinical applications at one department of pathology supported the potentials of SBO as a xylene substitute. In conclusion, we suggest that SBO is a safe and efficient substitute of xylene and may probably replace xylene without losing valuable diagnostic information.

  9. Reaction Mechanism for m- Xylene Oxidation in the Claus Process by Sulfur Dioxide

    KAUST Repository

    Sinha, Sourab

    2015-09-24

    In the Claus process, the presence of aromatic contaminants such benzene, toluene, and xylenes (BTX), in the H2S feed stream has a detrimental effect on catalytic reactors, where BTX form soot particles and clog and deactivate the catalysts. Among BTX, xylenes are proven to be most damaging contaminant for catalysts. BTX oxidation in the Claus furnace, before they enter catalyst beds, provides a solution to this problem. A reaction kinetics study on m-xylene oxidation by SO2, an oxidant present in Claus furnace, is presented. The density functional theory is used to study the formation of m-xylene radicals (3-methylbenzyl, 2,6-dimethylphenyl, 2,4-dimethylphenyl, and 3,5-dimethylphenyl) through H-abstraction and their oxidation by SO2. The mechanism begins with SO2 addition on the radicals through an O-atom rather than the S-atom with the release of 180.0-183.1 kJ/mol of reaction energies. This exothermic reaction involves energy barriers in the range 3.9-5.2 kJ/mol for several m-xylene radicals. Thereafter, O-S bond scission takes place to release SO, and the O-atom remaining on aromatics leads to CO formation. Among four m-xylene radicals, the resonantly stabilized 3-methylbenzyl exhibited the lowest SO2 addition and SO elimination rates. The reaction rate constants are provided to facilitate Claus process simulations to find conditions suitable for BTX oxidation. © 2015 American Chemical Society.

  10. Reaction Mechanism for m- Xylene Oxidation in the Claus Process by Sulfur Dioxide

    KAUST Repository

    Sinha, Sourab; Raj, Abhijeet; Al Shoaibi, Ahmed S.; Chung, Suk-Ho

    2015-01-01

    In the Claus process, the presence of aromatic contaminants such benzene, toluene, and xylenes (BTX), in the H2S feed stream has a detrimental effect on catalytic reactors, where BTX form soot particles and clog and deactivate the catalysts. Among BTX, xylenes are proven to be most damaging contaminant for catalysts. BTX oxidation in the Claus furnace, before they enter catalyst beds, provides a solution to this problem. A reaction kinetics study on m-xylene oxidation by SO2, an oxidant present in Claus furnace, is presented. The density functional theory is used to study the formation of m-xylene radicals (3-methylbenzyl, 2,6-dimethylphenyl, 2,4-dimethylphenyl, and 3,5-dimethylphenyl) through H-abstraction and their oxidation by SO2. The mechanism begins with SO2 addition on the radicals through an O-atom rather than the S-atom with the release of 180.0-183.1 kJ/mol of reaction energies. This exothermic reaction involves energy barriers in the range 3.9-5.2 kJ/mol for several m-xylene radicals. Thereafter, O-S bond scission takes place to release SO, and the O-atom remaining on aromatics leads to CO formation. Among four m-xylene radicals, the resonantly stabilized 3-methylbenzyl exhibited the lowest SO2 addition and SO elimination rates. The reaction rate constants are provided to facilitate Claus process simulations to find conditions suitable for BTX oxidation. © 2015 American Chemical Society.

  11. The Role of Musk in Relieving the Neurodegenerative Changes Induced After Exposure to Chronic Stress.

    Science.gov (United States)

    Abd El Wahab, Manal Galal; Ali, Soad Shaker; Ayuob, Nasra Naeim

    2018-06-01

    This study aimed to evaluate the effect induced by musk on Alzheimer's disease-such as neurodegenerative changes in mice exposed to chronic unpredictable mild stress (CUMS). Forty male Swiss albino mice were divided into 4 groups (n = 10); control, CUMS, CUMS + fluoxetine, CUMS + musk. At the end of the experiment, behavior of the mice was assessed. Serum corticosterone level, hippocampal protein level of the glucocorticoid receptors, and brain-derived neurotropic factor were also assessed. Hippocampus was histopathologically examined. Musk improved depressive status induced after exposure to CUMS as evidenced by the forced swimming and open field tests and improved the short-term memory as evidenced by the elevated plus maze test. Musk reduced both corticosterone levels and the hippocampal neurodegenerative changes observed after exposure to CUMS. These improvements were comparable to those induced by fluoxetine. Musk alleviated the memory impairment and neurodegenerative changes induced after exposure to the chronic stress.

  12. Solid-Liquid Equilibria for the Binary Mixtures 1,4-Xylene + Ethylbenzene and 1,4-Xylene + Toluene

    DEFF Research Database (Denmark)

    Huyghe, Raphaël; Rasmussen, Peter; Thomsen, Kaj

    2004-01-01

    Solid-liquid equilibrium (SLE) data for the binary mixtures 1,4-xylene + ethylbenzene, and 1,4-xylene + toluene have been measured using differential scanning calorimetry (DSC) in the temperature range from 133.15 K to 293.15 K.......Solid-liquid equilibrium (SLE) data for the binary mixtures 1,4-xylene + ethylbenzene, and 1,4-xylene + toluene have been measured using differential scanning calorimetry (DSC) in the temperature range from 133.15 K to 293.15 K....

  13. Volatilisation of o-Xylene from Sandy Soil

    DEFF Research Database (Denmark)

    Lindhardt, Bo; Christensen, Thomas Højlund; Brun, Adam

    1994-01-01

    The diffusive release of o-xylene from two soils with different contents of organic carbon (1.1 % and 0.11 % TOC) and with two different water contents (app. 5 % w/w and 15 % w/w was studied in the laboratory. The soils were spiked with o-xylene in the laboratory. The fluxes were measured over...

  14. Advertising displays of male Musk Ducks indicate population subdivision across the Nullarbor Plain of Australia

    Science.gov (United States)

    McCracken, K.G.; Fullagar, P.J.; Slater, E.C.; Paton, D.C.; Afton, A.D.

    2002-01-01

    Acoustic advertising displays (n=75) of male Musk Ducks Biziura lobata were analysed at ten widely spaced geographic localities in South Australia, Victoria, and Western Australia. Vocalisations differed in a fixed, non-overlapping pattern between allopatric Musk Duck populations in southeastern and southwestern Australia. These findings suggest that Musk Duck populations are subdivided by the Nullarbor Plain, the arid treeless desert at the head of the Great Australian Bight. Three vocalisations performed by male Musk Ducks not previously reported in the literature were documented also. Vocalisations of captive Musk Ducks collected from different geographic regions (southeast and southwest) differed between regions from which captives originally were collected and were unlike those performed by wild birds. Based on calls of immature Musk Ducks, acoustic variation within regional populations and the apparent inability of captive Musk Ducks reared in isolation to develop the wild type adult call, regional dialects seemingly are acquired in a social context by repeated observance of adult males and some combination of social imprinting, learning, or practice.

  15. Bridging the gap between traffic generated health stressors in urban areas: Predicting xylene levels in EU cities

    International Nuclear Information System (INIS)

    Vlachokostas, Ch.; Michailidou, A.V.; Spyridi, D.; Moussiopoulos, N.

    2013-01-01

    Many citizens live, work, commute, or visit traffic intensive spaces and are exposed to high levels of chemical health stressors. However, urban conurbations worldwide present monitoring “shortage” – due to economical and/or practical constraints – for toxic stressors such as xylene isomers, which can pose human health risks. This “shortage” may be covered by the establishment of associations between rarely monitored substances such as xylenes and more frequently monitored (i.e. benzene) or usually monitored (i.e. CO). Regression analysis is used and strong statistical relationships are detected. The adopted models are applied to EU cities and comparison between measurements and predictions depicts their representativeness. The analysis provides transferability insights in an effort to bridge the gap between traffic-related stressors. Strong associations between substances of the air pollution mixture may be influential to interpret the complexity of the causal chain, especially if a synergetic exposure assessment in traffic intensive spaces is considered. -- Highlights: •EU cities present monitoring shortage for health stressors such as xylenes. •The multi-stressor multi-city stepwise regression modelling approach is presented. •Strong linear relationships between xylenes and toluene, benzene, CO are detected. •Modelling results are in good agreement with the respective available measurements. •Toluene seems the optimal marker to predict xylene trends in traffic environments. -- The multi-stressor, multi-city stepwise regression modelling approach develops reliable statistical associations which capture m,p-xylene and o-xylene trends in EU traffic intensive environments

  16. Characterization of CD4 and CD8 T Cell Responses in MuSK Myasthenia Gravis

    Science.gov (United States)

    Yi, JS; Guidon, A; Sparks, S; Osborne, R; Juel, VC; Massey, JM; Sanders, DB; Weinhold, KJ; Guptill, JT

    2014-01-01

    Muscle specific tyrosine kinase myasthenia gravis (MuSK MG) is a form of autoimmune MG that predominantly affects women and has unique clinical features, including prominent bulbar weakness, muscle atrophy, and excellent response to therapeutic plasma exchange. Patients with MuSK MG have predominantly IgG4 autoantibodies directed against MuSK on the postsynaptic muscle membrane. Lymphocyte functionality has not been reported in this condition. The goal of this study was to characterize T-cell responses in patients with MuSK MG. Intracellular production of IFN-gamma, TNF-alpha, IL-2, IL-17, and IL-21 by CD4+ and CD8+ T-cells was measured by polychromatic flow cytometry in peripheral blood samples from 11 Musk MG patients and 10 healthy controls. Only one MuSK MG patient was not receiving immunosuppressive therapy. Regulatory T-cells (Treg) were also included in our analysis to determine if changes in T cell function were due to altered Treg frequencies. CD8+ T-cells from MuSK MG patients had higher frequencies of polyfunctional responses than controls, and CD4+ T-cells had higher IL-2, TNF-alpha, and IL-17. MuSK MG patients had a higher percentage of CD4+ T-cells producing combinations of IFN-gamma/IL-2/TNF-gamma, TNF-alpha/IL-2, and IFN-gamma/TNF-alpha. Interestingly, Treg numbers and CD39 expression were not different from control values. MuSK MG patients had increased frequencies of Th1 and Th17 cytokines and were primed for polyfunctional proinflammatory responses that cannot be explained by a defect in Treg function or number. PMID:24378287

  17. NTP Toxicology and Carcinogenesis Studies of Xylenes (Mixed) (60% m-Xylene, 14% p-Xylene, 9% o-Xylene, and 17% Ethylbenzene) (CAS No. 1330-20-7) in F344/N Rats and B6C3F1 Mice (Gavage Studies).

    Science.gov (United States)

    1986-12-01

    The technical grade of xylenes (mixed) (hereafter termed xylenes) contains the three isomeric forms and ethylbenzene (percentage composition shown above). The annual production for 1985 was approximately 7.4 x 108 gallons. Xylenes is used as a solvent and a cleaning agent and as a degreaser and is a constituent of aviation and automobile fuels. Xylenes is also used in the production of benzoic acid, phthalate anhydride, and isophthalic and terephthalic acids as well as their dimethyl esters. Toxicology and carcinogenesis studies of xylenes were conducted in laboratory animals because a large number of workers are exposed and because the long- term effects of exposure to xylenes were not known. Exposure for the present studies was by gavage in corn oil. In single-administration studies, groups of five F344/N rats and B6C3F1 mice of each sex received 500, 1,000, 2,000, 4,000, or 6,000 mg/kg. Administration of xylenes caused deaths at 6,000 mg/kg in rats and mice of each sex and at 4,000 mg/kg in male rats. In rats, clinical signs observed within 24 hours of dosing at 4,000 mg/kg included prostration, muscular incoordination, and loss of hind limb movement; these effects continued through the second week of observation. Tremors, prone position, and slowed breathing were recorded for mice on day 3, but all mice appeared normal by the end of the 2- week observation period. In 14- day studies, groups of five rats of each sex were administered 0, 125, 250, 500, 1,000, or 2,000 mg/kg, and groups of five mice of each sex received 0, 250, 500, 1,000, 2,000, or 4,000 mg/kg. Chemical- related mortality occurred only at 2,000 mg/kg in rats and at 4,000 mg/kg in mice. Rats and mice exhibited shallow breathing and prostration within 48 hours following dosing at 2,000 mg/kg. These signs persisted until day 12 for rats, but no clinical signs were noted during the second week for mice. In 13- week studies, groups of 10 rats of each sex received 0, 62.5, 125, 250, 500, or 1,000 mg

  18. A Novel Non-Toxic Xylene Substitute (SBO) for Histology

    OpenAIRE

    Kunhua, Wang; Chuming, Fan; Tao, Lai; Yanmei, Yang; Xin, Yang; Xiaoming, Zhang; Xuezhong, Guo; Xun, Lai

    2011-01-01

    Xylene has been generally used as a clearing and deparaffinizing agent in histology. Because of the potential toxic and flammable nature of xylene, its substitutes have been introduced into some laboratories. In this study, we introduced a novel, non-toxic xylene substitute (SBO), which was generated through a mixture of 86% of white oil No.2 and 14% of N-heptane. SBO had a high boiling point (188°C) and flash point (144°C) coupled with a scentless and decreased volatility. To compare the eff...

  19. Effects of four synthetic musks on the life cycle of the harpacticoid copepod Nitocra spinipes

    DEFF Research Database (Denmark)

    Breitholtz, M.; Wollenberger, Leah; Dinan, L.

    2003-01-01

    A full life-cycle (:! 26 days exposure) toxicity test with the harpacticoid copepod Nitocra spinipes was used to study the effects of one nitro musk (musk ketone) as well as three polycyclic musks (Tonalide(TM), Celestolide(TM) and Galaxolide(TM)). A subchronic individual life-table endpoint......, the larval development rate, was recorded after 7-8 days exposure of juveniles and was significantly decreased in copepods exposed to sublethal concentrations of musk ketone, Celestolide(TM) and Galaxolide(TM). However, none of the Tonalide(TM) concentrations had any effect on larval development. The lowest...... significantly affected r(m) (***P copepods were dead at the end of the exposures. This shows that a sensitive individual life-table endpoint is protective over the population-level endpoint r(m). Though we think...

  20. Inhibition of larval development of the marine copepod Acartia tonsa by four synthetic musk substances

    DEFF Research Database (Denmark)

    Wollenberger, Leah; Breitholtz, M.; Kusk, Kresten Ole

    2003-01-01

    A nitro musk (musk ketone). and three polycyclic musks (Tonalide(TM), Galaxolide(TM) and Celestolide(TM)) were tested for acute and subchronic effects on a marine crustacean, the calanoid copepod Acartia tonsa. Sublethal effects on A. tonsa larvae were investigated with a rapid and cost effective...... bioassay, which is based on the easily detectable morphological change from the last nauplius to the first copepodite stage during copepod larval development. The inhibition of larval development after 5 days exposure was a very sensitive endpoint, with 5-d-EC(50)-values as low as 0.026 mg/l (Tonalide...... of synthetic musks, for which there is little published ecotoxicological information available regarding Crustacea. It is suggested that subchronic and chronic copepod toxicity tests should be used more frequently for risk assessment of environmental pollutants. (C) 2002 Elsevier Science B.V. All rights...

  1. Synthetic Musk fragrances in Trout from Danish fish farms and human milk

    DEFF Research Database (Denmark)

    Duedahl-Olesen, Lene; Cederberg, Tommy Licht; Pedersen, K. H.

    2005-01-01

    Synthetic musk compounds used in detergents and cosmetics include nitro and polycyclic musk compounds. These compounds are discharged after use via domestic wastewater and sewage treatment plants to the aquatic environment. Quantitative detection of nitro musk and polycyclic musk compounds by GC....../HRMS in Danish farmed trout and human milk from primiparous mothers are reported. The polycyclic musk, HHCB, dominated the synthetic musk compounds found in trout samples from 1999 with a median concentration of 5.0 mu g/kg fresh weight (n.d.-52.6 mu g/kg fresh weight) and in trout samples collected in 2003....../kg fresh weight in 1999 and to a median less than the detection limit (0.23 mu g/kg fresh weight) in 2003. HHCB also dominated in Danish human milk samples collected in 1999 with a median concentration of 147 mu g/kg fat (38.0-422 mu g/kg fat). Human dietary intake assessment and body burden calculations...

  2. Dealkylation of alkylbenzenes: a significant pathway in the toluene, o-, m-, p-xylene + OH reaction.

    Science.gov (United States)

    Noda, Jun; Volkamer, Rainer; Molina, Mario J

    2009-09-03

    The OH-radical initiated oxidation of a series of monocyclic aromatic hydrocarbons (benzene, toluene, o-, m-, and p-xylene) in the presence of oxygen and NO(x) was investigated in a flowtube coupled with a chemical ionization mass spectrometer (CIMS). OH-radical addition to the aromatic ring--the major reaction pathway--has previously been shown to have a particular sensitivity to experimental conditions. This is the first flowtube study that demonstrates the atmospheric relevance of product yields from the OH-addition channel on the millisecond time scale (35-75 ms); the phenol yield from benzene and cresol yields from toluene are found to be 51.0 +/- 4.3% and 17.7 +/- 2.1%, in excellent agreement with previous studies under close to atmospheric conditions. We further report unambiguous experimental evidence that dealkylation is a novel and significant pathway for toluene and o-, m-, and p-xylene oxidation. At 150 Torr of O2 partial pressure, toluene is found to dealkylate with a yield of 5.4 +/- 1.2% phenol; similarly, m-, o-, and p-xylene dealkylate with yields of 11.2 +/- 3.8%, 4.5 +/- 3.2%, and 4.3 +/- 3.1% cresol, respectively. A dealkylation mechanism via OH-addition in the ipso position is feasible (DeltaH = -9 kcal/mol for phenol formation from toluene) but does not lend itself easily to explain the significant isomer effect observed among xylenes; instead an alternative mechanism is presented that can explain this isomer effect and forms phenol and likely epoxide type products with identical m/z (indistinguishable in our CIMS analysis) via a carbene-type intermediate. Dealkylation adds to the atmospheric production of phenol- and likely epoxide-type products, with aldehydes as expected co-products, and helps improve the carbon balance in the initial stages of aromatic oxidation.

  3. Landfills as sources of polyfluorinated compounds, polybrominated diphenyl ethers and musk fragrances to ambient air

    Science.gov (United States)

    Weinberg, Ingo; Dreyer, Annekatrin; Ebinghaus, Ralf

    2011-02-01

    In order to investigate landfills as sources of polyfluorinated compounds (PFCs), polybrominated diphenyl ethers (PBDEs) and synthetic musk fragrances to the atmosphere, air samples were simultaneously taken at two landfills (one active and one closed) and two reference sites using high volume air samplers. Contaminants were accumulated on glass fiber filters (particle phase) and PUF/XAD-2/PUF cartridges (gas phase), extracted by methyl-tert butyl ether/acetone (neutral PFCs), methanol (ionic PFCs) or hexane/acetone (PBDEs, musk fragrances), and detected by GC-MS (neutral PFCs, PBDEs, musk fragrances) or HPLC-MS/MS (ionic PFCs). Total concentrations ranged from 84 to 706 pg m -3 (volatile PFCs, gas phase), from fragrances, gas + particle phase) and from 1 to 11 pg m -3 (PBDEs, gas + particle phase). Observed sum concentrations of PFCs and synthetic musk fragrances and partly PBDE concentrations were elevated at landfill sites compared to corresponding reference sites. Concentrations determined at the active landfill were higher than those of the inactive landfill. Overall, landfills can be regarded as a source of synthetic musk fragrances, several PFCs and potentially of PBDEs to ambient air.

  4. Substrate interactions of benzene, toluene, and para-xylene during microbial degradation by pure cultures and mixed culture aquifer slurries

    International Nuclear Information System (INIS)

    Alvarez, P.J.J.; Vogel, T.M.

    1991-01-01

    Release of petroleum hydrocarbons in the environment is a widespread occurrence. One particular concern is the contamination of drinking water sources by the toxic, water-soluble, and mobile petroleum components benzene, toluene, and xylene (BTX). Benzene, toluene, and p-xylene (BTX) were degraded by indigenous mixed cultures in sandy aquifer material and by two pure cultures isolated from the same site. Although BTX compounds have a similar chemical structure, the fate of individual BTX compounds differed when the compounds were fed to each pure culture and mixed culture aquifer slurries. The identification of substrate interactions aided the understanding of this behavior. Beneficial substrate interactions included enhanced degradation of benzene-dependent degradation of toluene and p-xylene by Arthrobacter sp. strain HCB. Detrimental substrate interactions included retardation in benzene and toluene degradation by the presence of p-xylene in both aquifer slurries and Pseudomonas incubations. The catabolic diversity of microbes in the environment precludes generalizations about the capacity of individual BTX compounds to enhance or inhibit the degradation of other BTX compounds

  5. Modelling of tracer-kinetic results using xylene isomerization as an example

    International Nuclear Information System (INIS)

    Bauer, F.J.; Dermietzel, J.; Roesseler, M.; Koch, H.

    1976-01-01

    The analysis of results from differential or/and integral reactor experiments often admits the interpretation of a chemical reaction in several ways. In addition, the use of mathematical methods for the model selection and planning of experiments is rendered more difficult by great confidence intervals of the ascertained model parameters. The application of radioactively labelled molecules results in improving the knowledge of reaction mechanisms as well as the assessment of parameters obtained. This is shown on the basis of modelling the isomerization of xylene. (author)

  6. Replacing xylene with n-heptane for paraffin embedding.

    Science.gov (United States)

    Stockert, J C; López-Arias, B; Del Castillo, P; Romero, A; Blázquez-Castro, A

    2012-10-01

    In standard histological technique, aromatic solvents such as xylene and toluene are used as clearing agents between ethanol dehydration and paraffin embedding. In addition, these solvents are used for de-waxing paraffin sections. Unfortunately, these solvents are harmful and therefore adequate substitutes would be useful. We suggest the use of n-heptane as a convenient substitute for xylene. Paraffin sections of rat tissues processed with n-heptane and stained with hematoxylin-eosin or Masson's trichrome showed proper embedment, well preserved morphology and excellent staining.

  7. "Occupational Exposure To Xylene In Workers, Employing At Pathology Wards Of Hospitals Belonging To The Qazvin University Of Medical Sciences "

    Directory of Open Access Journals (Sweden)

    Shah Taheri SJ

    2005-05-01

    Full Text Available Background: Nowadays, aromatic hydrocarbons such as benzene, toluene, and xylene are extensively used in the different environments and industries, causing adverse effects on individuals who are being exposed occupationally and environmentally to these hazardous compounds. In this study, occupational exposure to xylene in workers, employing at pathology wards of hospitals belonging to the Qazvin University of Medical Sciences have been investigated. Materials and Methods: Methyl Hiporic Acid (MHA as a main metabolite of xylene in urine was used to evaluate the workers exposure to this chemical. The urine samples were taken from all 30 workers from 4 hospitals, i.e. Kosar, Shahid Rajaei, Booali and Qods. Through this study, 30 administrative employees were also selected as control group. The direct DBA colorimetric method was used to measure MHA in the workers urine. Results: The results obtained from this study showed that, there were significant differences between MHA and working days, type of jobs, and length of exposure time. This study also showed that, there were no significant differences between urinary MHA concentration and sex, age, and smoking habit. Conclusion: Through this study, it was also clearly obtained that, xylene exposure can not affect on the total and direct serum bilirobin in the workers blood. Finally, it is worth mentioning that, although this study showed no acute exposure to xylene in hospitals pathology wards, the effect of chronic exposure to such compound cannot be ignored, therefore protecting workers against like these organic solvents are strongly recommended as their TLVs are considerably being reduced during these years

  8. A Green Alternative to Aluminum Chloride Alkylation of Xylene

    Science.gov (United States)

    Sereda, Grigoriy A.; Rajpara, Vikul B.

    2007-01-01

    An acutely less toxic 2-bromobutane is used to develop a simple graphite-promoted procedure of alkylation of p-xylene. It is further demonstrated that aluminum chloride is not required, the need for aqueous workup is eliminated, waste solutions are not produced and the multiple use of the catalyst is allowed.

  9. Environmental risk assessment of the polycyclic musks AHTN and HHCB according to the EU-TGD

    NARCIS (Netherlands)

    Plassche EJ van de; Balk F; CSR

    1997-01-01

    An environmental risk assessment has been carried out for the polycyclic musks AHTN and HHCB according to the EU Technical Guidance Document for Environmental Risk Assessment for New and Existing Substances. AHTN and HHCB are used in fragrances for cosmetics and detergents. Both substances are high

  10. Assessment of genotoxicity of methyl-tert-butyl ether, benzene, toluene, ethylbenzene, and xylene to human lymphocytes using comet assay

    International Nuclear Information System (INIS)

    Chen, Colin S.; Hseu, You C.; Liang, Shih H.; Kuo, J.-Y.; Chen, Ssu. C.

    2008-01-01

    Methyl-tert-butyl ether (MTBE) is a gasoline oxygenate and antiknock additive substituting for lead alkyls currently in use worldwide. Benzene, toluene, ethylbenzene, and xylene (BTEX) are volatile monoaromatic hydrocarbons which are commonly found together in crude petroleum and petroleum products such as gasoline. The aim of this study is to evaluate the genotoxic effects of these tested chemicals in human lymphocytes. Using the alkaline comet assay, we showed that all of the tested chemicals induce DNA damage in isolated human lymphocytes. This effect could follow from the induction of DNA strands breaks. The neutral version of the test revealed that MTBE, benzene, and xylenes induce DNA double-strand breaks at 200 μM. Apart from MTBE, the spin traps, 5,5-dimethyl-pyrroline-N-oxide (DMPO) and N-tert-butyl-α-phenylnitrone (PBN) can decrease the level of DNA damage in BTEX at 200 μM. This indicated that DNA damage could result from the participation of free radicals in DNA-damaging effect, which was further supported by the fact that post-treatment of formamidopyrimidine-DNA glycosylase (Fpg), enzyme recognizing oxidized DNA purines, gave rise to a significant increase in the extent of DNA damage in cells treated with benzene, and xylene at 200 μM. The results obtained suggested that MTBE and BTEX could induce a variety type of DNA damage such as single-strand breaks (SSBs), double-strand breaks (DSBs), and oxidative base modification

  11. Separation and effect of residual moisture in liquid phase adsorption of xylene on y zeolites

    Directory of Open Access Journals (Sweden)

    P. Lahot

    2014-06-01

    Full Text Available The separation of p-xylene and m-xylene from C8 aromatic hydrocarbon feed using Y zeolites is investigated. Effect of residual moisture on p-xylene adsorption on BaY was measured in order to optimize the activation temperature of the adsorbent. The results show that with an increase in temperature the moisture on the adsorbent decreases. An optimum loading of moisture is required for adsorption of xylene on the adsorbents. The Everett equation is used to determine the adsorption capacity and selectivity. It has been found that the adsorbents best suited for the separation of p-xylene, m-xylene, o-xylene and ethyl benzene from the mixture of C8 aromatics are NaY, NaY, BaY and KY, respectively. The XRD results show that the crystallinity of the adsorbent decreases upon exchanging the zeolites to K+ and Ba2+ ions.

  12. Phenomena Based Process Intensification of Toluene Methylation for Sustainable Para-xylene Production

    DEFF Research Database (Denmark)

    Anantasarn, Nateetorn; Babi, Deenesh Kavi; Suriyapraphadilok, Uthaiporn

    2016-01-01

    The objective of this work is to generate more sustainable intensified process designs for the production of important chemicals in the petrochemical sector. A 3-stage approach is applied. In stage 1, the base case design is generated or selected from literature. In stage 2, the base case design...... is analysed in terms of economics, sustainability and LCA factors in order to identify process hot-spots that are translated into design targets. In stage 3, intensified flowsheet alternatives are generated that match the targets and thereby eliminate and/or minimize the process hot-spots using a phenomena...... operations to generate more sustainable designs. An overview of the key concepts and framework are presented together with the results from a case study highlighting the application of the framework to the sustainable design of a production process for para-xylene, which is an important chemical utilized...

  13. Adsorption of xylene para- and meta- isomers in NaX and BaX zeolites. Study of properties-structure relations; Adsorption des isomeres para- et meta- du xylene dans les zeolithes NaX et BaX. Etude des relations proprietes-structure

    Energy Technology Data Exchange (ETDEWEB)

    Descours, A.

    1997-02-14

    The separation of para-xylene from C8 aromatics is performed industrially bu adsorption process on zeolitic molecular sieves. The sorption properties of these zeolites are strongly linked to their structure, and their comprehension require an accurate knowledge of the interactions between sorbate molecules and zeolitic structure. The aim of this work is to characterise from a structural point of view the adsorption of para- and meta-xylenes in BaX and NaX zeolites. The former is selective for para-xylene, and the latter has not selective properties for para- and meta-isomers of xylene. For each zeolite, the adsorption of pure para-xylene and meta-xylene or a mixture of the two isomers, is investigated as a function of coverage. Powder neutron diffraction is used to determine the crystalline structure of these zeolites and the different crystallographic adsorption sites of the molecules. The influence of coverage on sorbate-sorbent and sorbate-sorbate interactions is investigated. Infrared spectroscopy allows to determine the chemical environment of the sorbate molecules at low coverage or when the coverage increases, and is particularly effective for the study of the binary mixture of xylenes. This study is performed by sorbing a mixture of xylene isomers, or by sorbing these isomers successively. Infrared studies and crystallographic analysis are compared in order to get a consistent description of adsorption mechanism of xylene isomers for both zeolites as a function of coverage. The role of coverage, of cation type, an the presence of the two xylene isomers is the super-cages is essential. For both zeolites, the increase of coverage actually leads to steric hindrances between sorbed molecules and molecular rearrangements. These reorganizations are connected to the cationic distribution of NaX and BaX zeolites. The sorbed molecules are connected to the cationic distribution of NaX and BaX zeolites. The sorbed molecules are particularly confined in BaX zeolite

  14. High-temperature rate constant measurements for OH+xylenes

    KAUST Repository

    Elwardani, Ahmed Elsaid

    2015-06-01

    The overall rate constants for the reactions of hydroxyl (OH) radicals with o-xylene (k 1), m-xylene (k 2), and p-xylene (k 3) were measured behind reflected shock waves over 890-1406K at pressures of 1.3-1.8atm using OH laser absorption near 306.7nm. Measurements were performed under pseudo-first-order conditions. The measured rate constants, inferred using a mechanism-fitting approach, can be expressed in Arrhenius form as:k1=2.93×1013exp(-1350.3/T)cm3mol-1s-1(890-1406K)k2=3.49×1013exp(-1449.3/T)cm3mol-1s-1(906-1391K)k3=3.5×1013exp(-1407.5/T)cm3mol-1s-1(908-1383K)This paper presents, to our knowledge, first high-temperature measurements of the rate constants of the reactions of xylene isomers with OH radicals. Low-temperature rate-constant measurements by Nicovich et al. (1981) were combined with the measurements in this study to obtain the following Arrhenius expressions, which are applicable over a wider temperature range:k1=2.64×1013exp(-1181.5/T)cm3mol-1s-1(508-1406K)k2=3.05×109exp(-400/T)cm3mol-1s-1(508-1391K)k3=3.0×109exp(-440/T)cm3mol-1s-1(526-1383K) © 2015 The Combustion Institute.

  15. Pressurized liquid extraction-gas chromatography-mass spectrometry analysis of fragrance allergens, musks, phthalates and preservatives in baby wipes.

    Science.gov (United States)

    Celeiro, Maria; Lamas, J Pablo; Garcia-Jares, Carmen; Llompart, Maria

    2015-03-06

    Baby wipes and wet toilet paper are specific hygiene care daily products used on newborn and children skin. These products may contain complexes mixtures of harmful chemicals. A method based on pressurized liquid extraction (PLE) followed by gas chromatography-mass spectrometry (GC-MS) has been developed for the simultaneous determination of sixty-five chemical compounds (fragrance allergens, preservatives, musks, and phthalates) in wipes and wet toilet paper for children. These compounds are legislated in Europe according Regulation EC No 1223/2009, being twelve of them banned for their use in cosmetics, and one of them, 3-iodo-2-propynyl butylcarbamate (IPBC), is banned in products intended for children under 3 years. Also, propyl-, and butylparaben will be prohibited in leave-on cosmetic products designed for application on the nappy area of children under 3 years from April 2015. PLE is a fast, simple, easily automated technique, which permits to integrate a clean-up step during the extraction process reducing analysis time and stages. The proposed PLE-based procedure was optimized on real non-spiked baby wipe samples by means of experimental design to study the influence on extraction of parameters such as extraction solvent, temperature, extraction time, and sorbent type. Under the selected conditions, the method was validated showing satisfactory linearity, and intra-day, and inter-day precision. Recoveries were between 80-115% for most of the compounds with relative standard deviations (RSD) lower than 15%. Finally, twenty real samples were analyzed. Thirty-six of the target analytes were detected, highlighting the presence of phenoxyethanol in all analyzed samples at high concentration levels (up to 0.8%, 800μgg(-1)). Methyl paraben (MeP), and ethyl paraben (EtP) were found in 40-50% of the samples, and the recently banned isobutyl paraben (iBuP) and isopropyl paraben (iPrP), were detected in one and seven samples, respectively, at concentrations between

  16. A chromosomally based tod-luxCDABE whole-cell reporter for benzene, toluene, ethybenzene, and xylene (BTEX) sensing

    International Nuclear Information System (INIS)

    Applegate, B.M.; Kehrmeyer, S.R.; Sayler, G.S.

    1998-01-01

    A tod-luxCDABE fusion was constructed and introduced into the chromosome of Pseudomonas putida F1, yielding the strain TVA8. This strain was used to examine the induction of the tod operon when exposed to benzene, toluene, ethylbenzene, and xylene (BTEX) compounds and aqueous solutions of JP-4 jet fuel constituents. Since this system contained the complete lux cassette (luxCDABE), bacterial bioluminescence in response to putative chemical inducers of the tod operon was measured on-line in whole cells without added aldehyde substrate. There was an increasing response to toluene concentrations from 30 microg/liter to 50 mg/liter, which began to saturate at higher concentrations. The detection limit was 30 microg/liter. There was a significant light response to benzene, m- and p-xylenes, phenol, and water-soluble JP-4 jet fuel components, but there was no bioluminescence response upon exposure to o-xylene. The transposon insertion was stable and had no negative effect on cell growth

  17. Distortion dependent intersystem crossing: A femtosecond time-resolved photoelectron spectroscopy study of benzene, toluene, and p-xylene

    Directory of Open Access Journals (Sweden)

    Anne B. Stephansen

    2017-07-01

    Full Text Available The competition between ultrafast intersystem crossing and internal conversion in benzene, toluene, and p-xylene is investigated with time-resolved photoelectron spectroscopy and quantum chemical calculations. By exciting to S2 out-of-plane symmetry breaking, distortions are activated at early times whereupon spin-forbidden intersystem crossing becomes (partly allowed. Natural bond orbital analysis suggests that the pinnacle carbon atoms distorting from the aromatic plane change hybridization between the planar Franck-Condon geometry and the deformed (boat-shaped S2 equilibrium geometry. The effect is observed to increase in the presence of methyl-groups on the pinnacle carbon-atoms, where largest extents of σ and π orbital-mixing are observed. This is fully consistent with the time-resolved spectroscopy data: Toluene and p-xylene show evidence for ultrafast triplet formation competing with internal conversion, while benzene appears to only decay via internal conversion within the singlet manifold. For toluene and p-xylene, internal conversion to S1 and intersystem crossing to T3 occur within the time-resolution of our instrument. The receiver triplet state (T3 is found to undergo internal conversion in the triplet manifold within ≈100–150 fs (toluene or ≈180–200 fs (p-xylene as demonstrated by matching rise and decay components of upper and lower triplet states. Overall, the effect of methylation is found to both increase the intersystem crossing probability and direct the molecular axis of the excited state dynamics.

  18. Biodiesel production from wet municipal sludge: evaluation of in situ transesterification using xylene as a cosolvent.

    Science.gov (United States)

    Choi, O K; Song, J S; Cha, D K; Lee, J W

    2014-08-01

    This study proposes a method to produce biodiesel from wet wastewater sludge. Xylene was used as an alternative cosolvent to hexane for transesterification in order to enhance the biodiesel yield from wet wastewater sludge. The water present in the sludge could be separated during transesterification by employing xylene, which has a higher boiling point than water. Xylene enhanced the biodiesel yield up to 8.12%, which was 2.5 times higher than hexane. It was comparable to the maximum biodiesel yield of 9.68% obtained from dried sludge. Xylene could reduce either the reaction time or methanol consumption, when compared to hexane for a similar yield. The fatty acid methyl esters (FAMEs) content of the biodiesel increased approximately two fold by changing the cosolvent from hexane to xylene. The transesterification method using xylene as a cosolvent can be applied effectively and economically for biodiesel recovery from wet wastewater sludge without drying process. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Food restriction, refeeding, and gastric fill fail to affect emesis in musk shrews

    OpenAIRE

    Horn, Charles C.; Still, Liz; Fitzgerald, Christiana; Friedman, Mark I.

    2009-01-01

    Nausea and emesis are common side effects of gastrointestinal disease. Reports indicate that ghrelin and endocannabinoids, agents that stimulate appetite, also reduce emesis evoked by chemotherapy treatment, which suggests that stimulation of feeding inhibits the emetic system. In the following study we conducted a more direct test of this hypothesis by determining the impact of manipulating the motivation to eat on emesis, using food restriction and refeeding. Emesis was induced in musk shre...

  20. Bioconcentration and acute toxicity of polycyclic musks in two benthic organisms (Chironomus riparius and Lumbriculus variegatus)

    NARCIS (Netherlands)

    Artola-Garicano, E.; Sinnige, T.L.; Holsteijn, I. van; Vaes, W.H.J.; Hermens, J.L.M.

    2003-01-01

    In the current study, the bioconcentration behavior and acute toxicity of two polycyclic musks, Tonalide® 7-acetyl-1,1,3,4,4,6,-hexamethyl-1,2,3,4,-tetrahydronaphthalene (AHTN) and Galaxolide® 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexa-methyl-cyclopenta[γ]-2- benzopyran (HHCB), were studied in two

  1. Long lasting perfume--a review of synthetic musks in WWTPs.

    Science.gov (United States)

    Homem, Vera; Silva, José Avelino; Ratola, Nuno; Santos, Lúcia; Alves, Arminda

    2015-02-01

    Synthetic musks have been used for a long time in personal care and household products. In recent years, this continuous input has increased considerably, to the point that they were recognized as emerging pollutants by the scientific community, due to their persistence in the environment, and hazardous potential to ecosystems even at low concentrations. The number of studies in literature describing their worldwide presence in several environmental matrices is growing, and many of them indicate that the techniques employed for their safe removal tend to be ineffective. This is the case of conventional activated sludge treatment plants (WWTPs), where considerable loads of synthetic musks enter mainly through domestic sewage. This review paper compiles and discusses the occurrence of these compounds in the sewage, effluents and sludge, main concentration levels and phase distributions, as well as the efficiency of the different methodologies of removal applied in these treatment facilities. To the present day, it has been demonstrated that WWTPs lack the ability to remove musks completely. This shows a clear need to develop new effective and cost-efficient remediation approaches and foresees potential for further improvements in this field. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Emendation and new species of Hapalorhynchus Stunkard, 1922 (Digenea: Schistosomatoidea) from musk turtles (Kinosternidae: Sternotherus) in Alabama and Florida rivers.

    Science.gov (United States)

    Roberts, Jackson R; Halanych, Kenneth M; Arias, Cova R; Folt, Brian; Goessling, Jeffrey M; Bullard, Stephen A

    2017-12-01

    Hapalorhynchus Stunkard, 1922 is emended based on morphological study of existing museum specimens (type and voucher specimens) and newly-collected specimens infecting musk turtles (Testudines: Kinosternidae: Sternotherus spp.) from rivers in Alabama and Florida (USA). Hapalorhynchus conecuhensis n. sp. is described from an innominate musk turtle, Sternotherus cf. minor, (type host) from Blue Spring (31°5'27.64″N, 86°30'53.21″W; Pensacola Bay Basin, Alabama) and the loggerhead musk turtle, Sternotherus minor (Agassiz, 1857) from the Wacissa River (30°20'24.73″N, 83°59'27.56″W; Apalachee Bay Basin, Florida). It differs from congeners by lacking a body constriction at level of the ventral sucker, paired anterior caeca, and a transverse ovary as well as by having a small ventral sucker, proportionally short posterior caeca, nearly equally-sized anterior and posterior testes, a small cirrus sac, and a uterus extending dorsal to the ovary and the anterior testis. Specimens of Hapalorhynchus reelfooti Byrd, 1939 infected loggerhead musk turtles, stripe-necked musk turtles (Sternotherus peltifer Smith and Glass, 1947), Eastern musk turtles (Sternotherus odoratus [Latreille in Sonnini and Latreille, 1801]), and S. cf. minor. Those of Hapalorhynchus cf. stunkardi infected S. minor and S. odoratus. Sternothorus minor, S. peltifer, and S. cf. minor plus S. minor and S. odoratus are new host records for H. reelfooti and H. cf. stunkardi, respectively. This is the first report of an infected musk turtle from the Coosa and Tallapoosa Rivers (Mobile-Tensaw River Basin), Pensacola Bay Basin, or Apalachee Bay Basin. Sequence analysis of the large subunit rDNA (28S) showed a strongly-supported clade for Hapalorhynchus. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Removal performance of toluene, p-xylene and ethylene using a plasma-pretreated biotrickling system

    Energy Technology Data Exchange (ETDEWEB)

    Kim, H.J.; Han, B.; Kim, S.J.; Kim, Y.J. [Korea Inst. of Machinery and Materials (Korea, Republic of)

    2010-07-01

    The use of biological systems for removing volatile organic compounds (VOCs) from gaseous emissions was discussed. The systems rely on microorganism activity and do not produce any secondary pollution. Recently, the integration of biofiltration and UV photooxidation has been performed to remove VOCs in air. The systems using both UV photooxidation and biofiltration removed recalcitrant and VOCs more effectively than a stand-alone process using only biofiltration, because the UV pre-treatment not only removes the gases, but also changes them to easily biodegradable and water soluble byproducts such as acids and aldehydes. The biotrickling filter in this study was exposed to toluene gas only for over one month to cultivate specific microorganisms. The non-thermal plasma was a dielectric barrier discharge (DBD) plasma. The performance for removing toluene, p-xylene, and ethylene by the biotrickling filter, the plasma reactor and the plasma-pretreated bio-trickling system was investigated at a variety of flow rates and inlet concentrations of the test gases. The experimental results showed that the removal efficiencies of the integrated system of non-thermal plasma and biotrickling filter for p-xylene and ethylene were enhanced by 28.0 and 29.7 percent respectively, and increased by only 5.3 percent for toluene, as compared to those of the stand-alone biotrickling filtration. It was concluded that the plasma-pretreated biofiltration system could enhance the performance of the biotrickling filter for removing VOC gases, particularly for reducing low biodegradable pollutants with high loading which are chemically different from the cultivated gases. 12 refs., 7 figs.

  4. Effects of prenatal exposure to xylene on postnatal development and behavior in rats

    DEFF Research Database (Denmark)

    Hass, Ulla; Lund, S. P.; Simonsen, L.

    1995-01-01

    The effects of prenatal exposure to the organic solvent xylene (dimethylbenzene, GAS-no 1330-20-7) on postnatal development and behavior in rats were studied. Pregnant rats (Mol:WIST) were exposed to 500 ppm technical xylene 6 h per day on gestation days 7-20. The dose level was selected so as no...

  5. Highly enriched Betaproteobacteria growing anaerobically with p-xylene and nitrate

    DEFF Research Database (Denmark)

    Rotaru, Amelia-Elena; Probian, Christina; Wilkes, Heinz

    2010-01-01

    The identity of the microorganisms capable of anaerobic p-xylene degradation under denitrifying conditions is hitherto unknown. Here, we report highly enriched cultures of freshwater denitrifying bacteria that grow anaerobically with p-xylene as the sole organic carbon source and electron donor. ...

  6. Using wintergreen oil for mounting mosquito larvae: a safer alternative to xylene.

    Science.gov (United States)

    Koay, J B; Natasya, N N; Nashithatul, Mag; Ihsanuddin, R; Salleh, F M; Azil, A H

    2016-01-01

    Permanent mounting of fourth instar mosquito larvae is essential for identifying Aedes spp. This procedure requires extensive exposure to xylene, a clearing agent in the mounting process. We investigated wintergreen oil as a substitute for xylene. Five hundred larvae were mounted on slides to evaluate shrinkage or expansion of specimens after clearing using xylene or wintergreen oil. We examined the ventral brush and siphonal hair tufts for species identification and for preservation of morphological characteristics after clearing specimens in xylene or wintergreen oil. Shrinkage of the length of whole larvae and width of the head, thorax and abdomen after mounting was significantly greater after clearing with xylene than with wintergreen oil. The length of the comb scale nearest the ventral brush was similar for both clearing agents. The clarity of the specimens after mounting was improved by clearing with wintergreen oil, but the integrity of the ventral brush and siphonal hair tufts were similar for both clearing agents.

  7. Formation yields of glyoxal and methylglyoxal from the gas-phase OH radical-initiated reactions of toluene, xylenes, and trimethylbenzenes as a function of NO2 concentration.

    Science.gov (United States)

    Nishino, Noriko; Arey, Janet; Atkinson, Roger

    2010-09-23

    Aromatic hydrocarbons comprise 20% of non-methane volatile organic compounds in urban areas and are transformed mainly by atmospheric chemical reactions with OH radicals during daytime. In this work we have measured the formation yields of glyoxal and methylglyoxal from the OH radical-initiated reactions of toluene, xylenes, and trimethylbenzenes over the NO2 concentration range (0.2-10.3) × 1013 molecules cm(-3). For toluene, o-, m-, and p-xylene, and 1,3,5-trimethylbenzene, the yields showed a dependence on NO2, decreasing with increasing NO2 concentration and with no evidence for formation of glyoxal or methylglyoxal from the reactions of the OH-aromatic adducts with NO2. In contrast, for 1,2,3- and 1,2,4-trimethylbenzene the glyoxal and methylglyoxal formation yields were independent of the NO2 concentration within the experimental uncertainties. Extrapolations of our results to NO2 concentrations representative of the ambient atmosphere results in the following glyoxal and methylglyoxal yields, respectively: for toluene, 26.0 ± 2.2% and 21.5 ± 2.9%; for o-xylene, 12.7 ± 1.9% and 33.1 ± 6.1%; for m-xylene, 11.4 ± 0.7% and 51.5 ± 8.5%; for p-xylene, 38.9 ± 4.7% and 18.7 ± 2.2%; for 1,2,3-trimethylbenzene, 4.7 ± 2.4% and 15.1 ± 3.3%; for 1,2,4-trimethylbenzene, 8.7 ± 1.6% and 27.2 ± 8.1%; and for 1,3,5-trimethylbenzene, 58.1 ± 5.3% (methylglyoxal).

  8. Development of an ultrasensitive PCR assay for polycyclic musk determination in fish.

    Science.gov (United States)

    Zhang, Xiaohan; Zhuang, Huisheng

    2018-05-01

    Polycyclic musks (PCMs) in the aquatic environment and organisms have become an emerging environmental issue because of their potential risk. The most used method for polycyclic musk determination is gas chromatography-mass spectrometry (GC-MS) with different sample extractions, which are somewhat expensive to operate, complex and laborious. In this study, a novel and ultrasensitive real-time polymerase chain reaction (PCR) assay with multiple signal amplification of carboxylic-DNA by gold nanoparticle-polyamidoamine conjugation (Au-PAMAM) was developed for determining polycyclic musks in fish. Hapten and immunogen were specially prepared. Polyclonal antibodies were produced based on the optimal immunisation, and the antibodies were characterised. Due to PAMAM's unique nanostructure of numerous functional amino groups, polyclonal antibody and carboxylic-DNA were immobilised by Au-PAMAM conjugation to develop the antibody-Au-PAMAM-DNA probes, which were used as a signal DNA amplifier in the PCR system. Compared with real-time immuno-PCR, this biological probe-amplified immuno-PCR (BPAI-PCR) assay had higher sensitivity due to the probes' higher ratio of signal DNA. Finally, the BPAI-PCR assay was applied to analyse AHTN (7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene,Tonalide) concentrations in fish samples in the range from 1 pg/L to 10 ng/L, giving an of LOD 0.61 pg/L. In general, due to the specificity of the antibody and novel nanoprobe design, this BPAI-PCR assay provided a potential way for trace analysis of AHTN in the aquatic organisms. The high concentrations of AHTN found in cultivated fish should encourage further toxicological studies.

  9. Musk ox (Ovibos moschatus) of the mammoth steppe

    DEFF Research Database (Denmark)

    Raghavan, Maanasa; Themudo, Goncalo Espregueira Cruz; Smith, Colin

    2014-01-01

    Stable carbon and nitrogen isotope ratios have been used as markers for palaeoclimatic and palaeoecological reconstructions across various geographical and temporal ranges. Such studies are essential for understanding how a particular species responded to changing environmental conditions...... in precipitation and that these variations were closely associated with events such as the cold and arid Last Glacial Maximum (LGM), Bolling-Allerod interstadial, Younger Dryas stadial and the warmer and humid Holocene. Regional differences in the isotopic composition of the musk ox populations are also noticeable...

  10. Real-time monitoring of benzene, toluene, and p-xylene in a photoreaction chamber with a tunable mid-infrared laser and ultraviolet differential optical absorption spectroscopy.

    Science.gov (United States)

    Parsons, Matthew T; Sydoryk, Ihor; Lim, Alan; McIntyre, Thomas J; Tulip, John; Jäger, Wolfgang; McDonald, Karen

    2011-02-01

    We describe the implementation of a mid-infrared laser-based trace gas sensor with a photoreaction chamber, used for reproducing chemical transformations of benzene, toluene, and p-xylene (BTX) gases that may occur in the atmosphere. The system performance was assessed in the presence of photoreaction products including aerosol particles. A mid-infrared external cavity quantum cascade laser (EC-QCL)-tunable from 9.41-9.88 μm (1012-1063 cm(-1))-was used to monitor gas phase concentrations of BTX simultaneously and in real time during chemical processing of these compounds with hydroxyl radicals in a photoreaction chamber. Results are compared to concurrent measurements using ultraviolet differential optical absorption spectroscopy (UV DOAS). The EC-QCL based system provides quantitation limits of approximately 200, 200, and 600 parts in 10(9) (ppb) for benzene, toluene, and p-xylene, respectively, which represents a significant improvement over our previous work with this laser system. Correspondingly, we observe the best agreement between the EC-QCL measurements and the UV DOAS measurements with benzene, followed by toluene, then p-xylene. Although BTX gas-detection limits are not as low for the EC-QCL system as for UV DOAS, an unidentified by-product of the photoreactions was observed with the EC-QCL, but not with the UV DOAS system.

  11. Reconstruction of Exposure to m-Xylene from Human Biomonitoring Data Using PBPK Modelling, Bayesian Inference, and Markov Chain Monte Carlo Simulation

    Science.gov (United States)

    McNally, Kevin; Cotton, Richard; Cocker, John; Jones, Kate; Bartels, Mike; Rick, David; Price, Paul; Loizou, George

    2012-01-01

    There are numerous biomonitoring programs, both recent and ongoing, to evaluate environmental exposure of humans to chemicals. Due to the lack of exposure and kinetic data, the correlation of biomarker levels with exposure concentrations leads to difficulty in utilizing biomonitoring data for biological guidance values. Exposure reconstruction or reverse dosimetry is the retrospective interpretation of external exposure consistent with biomonitoring data. We investigated the integration of physiologically based pharmacokinetic modelling, global sensitivity analysis, Bayesian inference, and Markov chain Monte Carlo simulation to obtain a population estimate of inhalation exposure to m-xylene. We used exhaled breath and venous blood m-xylene and urinary 3-methylhippuric acid measurements from a controlled human volunteer study in order to evaluate the ability of our computational framework to predict known inhalation exposures. We also investigated the importance of model structure and dimensionality with respect to its ability to reconstruct exposure. PMID:22719759

  12. Reconstruction of Exposure to m-Xylene from Human Biomonitoring Data Using PBPK Modelling, Bayesian Inference, and Markov Chain Monte Carlo Simulation

    Directory of Open Access Journals (Sweden)

    Kevin McNally

    2012-01-01

    Full Text Available There are numerous biomonitoring programs, both recent and ongoing, to evaluate environmental exposure of humans to chemicals. Due to the lack of exposure and kinetic data, the correlation of biomarker levels with exposure concentrations leads to difficulty in utilizing biomonitoring data for biological guidance values. Exposure reconstruction or reverse dosimetry is the retrospective interpretation of external exposure consistent with biomonitoring data. We investigated the integration of physiologically based pharmacokinetic modelling, global sensitivity analysis, Bayesian inference, and Markov chain Monte Carlo simulation to obtain a population estimate of inhalation exposure to m-xylene. We used exhaled breath and venous blood m-xylene and urinary 3-methylhippuric acid measurements from a controlled human volunteer study in order to evaluate the ability of our computational framework to predict known inhalation exposures. We also investigated the importance of model structure and dimensionality with respect to its ability to reconstruct exposure.

  13. Traditional Chinese medicine and sports drug testing: identification of natural steroid administration in doping control urine samples resulting from musk (pod) extracts.

    Science.gov (United States)

    Thevis, Mario; Schänzer, Wilhelm; Geyer, Hans; Thieme, Detlef; Grosse, Joachim; Rautenberg, Claudia; Flenker, Ulrich; Beuck, Simon; Thomas, Andreas; Holland, Ruben; Dvorak, Jiri

    2013-01-01

    The administration of musk extract, that is, ingredients obtained by extraction of the liquid secreted from the preputial gland or resulting grains of the male musk deer (eg, Moschus moschiferus), has been recommended in Traditional Chinese Medicine (TCM) applications and was listed in the Japanese pharmacopoeia for various indications requiring cardiovascular stimulation, anti-inflammatory medication or androgenic hormone therapy. Numerous steroidal components including cholesterol, 5α-androstane-3,17-dione, 5β-androstane-3,17-dione, androsterone, etiocholanolone, epiandrosterone, 3β-hydroxy-androst-5-en-17-one, androst-4-ene-3,17-dione and the corresponding urea adduct 3α-ureido-androst-4-en-17-one were characterised as natural ingredients of musk over several decades, implicating an issue concerning doping controls if used for the treatment of elite athletes. In the present study, the impact of musk extract administration on sports drug testing results of five females competing in an international sporting event is reported. In the course of routine doping controls, adverse analytical findings concerning the athletes' steroid profile, corroborated by isotope-ratio mass spectrometry (IRMS) data, were obtained. The athletes' medical advisors admitted the prescription of TCM-based musk pod preparations and provided musk pod samples for comparison purposes to clarify the antidoping rule violation. Steroid profiles, IRMS results, literature data and a musk sample obtained from a living musk deer of a local zoo conclusively demonstrated the use of musk pod extracts in all cases which, however, represented a doping offence as prohibited anabolic-androgenic steroids were administered.

  14. Individual- and population-level effects of the synthetic musk, HHCB, on the deposit-feeding polychaete, Capitella sp. I

    DEFF Research Database (Denmark)

    Ramskov, Tina; Selck, Henriette; Salvito, Daniel

    2009-01-01

    A life table response experiment lasting 120 d was used to investigate the effects of the synthetic polycyclic musk HHCB (1,3,4,6,7,8-hexahydro-4,6,6,7,8-hexamethylcyclopenta-gamma-2-benzopyrane; 0, 1.5, 26, 123, and 168 mg/kg dry wt sediment) on the life history of the infaunal polychaete...

  15. East-west genetic differentiation in Musk Ducks (Biziura lobata) of Australia suggests late Pleistocene divergence at the Nullarbor Plain

    Science.gov (United States)

    Guay, P.-J.; Chesser, R.T.; Mulder, R.A.; Afton, A.D.; Paton, D.C.; McCracken, K.G.

    2010-01-01

    Musk Ducks (Biziura lobata) are endemic to Australia and occur as two geographically isolated populations separated by the Nullarbor Plain, a vast arid region in southern Australia. We studied genetic variation in Musk Duck populations at coarse (eastern versus western Australia) and fine scales (four sites within eastern Australia). We found significant genetic structure between eastern and western Australia in the mtDNA control region (??ST = 0. 747), one nuclear intron (??ST = 0.193) and eight microsatellite loci (FST = 0.035). In contrast, there was little genetic structure between Kangaroo Island and adjacent mainland regions within eastern Australia. One small population of Musk Ducks in Victoria (Lake Wendouree) differed from both Kangaroo Island and the remainder of mainland eastern Australia, possibly due to genetic drift exacerbated by inbreeding and small population size. The observed low pairwise distance between the eastern and western mtDNA lineages (0.36%) suggests that they diverged near the end of the Pleistocene, a period characterised by frequent shifts between wet and arid conditions in central Australia. Our genetic results corroborate the display call divergence and Mathews' (Austral Avian Record 2:83-107, 1914) subspecies classification, and confirm that eastern and western populations of Musk Duck are currently isolated from each other. ?? 2010 Springer Science+Business Media B.V.

  16. THE CONSERVATION AND POTENTIAL HABITAT OF THE HIMALAYAN MUSK DEER, MOSCHUS CHRYSOGASTER, IN THE PROTECTED AREAS OF NEPAL

    Directory of Open Access Journals (Sweden)

    Achyut ARYAL

    2011-06-01

    Full Text Available The Himalayan musk deer (Moschus chrysogaster is a cervid distributed from the eastern to the western Himalayas of Nepal. The species is listed as endangered in appendix I of IUCN Red data, and protected in Nepal under the National Parks and Wildlife Conservation Act of 1973. Musk deer occupy the middle to the higher mountain regions, which cover 12 protected areas of Nepal (6 national parks, 5 conservation areas, 1 hunting reserve. However, of the 30177.19 km2 potential habitat, only 19.26% (5815.08 km2 is inside the protected areas and the remaining 80.73% falls outside the protected areas. Consequently, poaching, habitat destruction, livestock grazing and forest fire in the musk deer habitat are important challenges for the conservation of musk deer in the country. A thorough status survey in and outside the protected areas should be carried out and a species-focused conservation action plan should be prepared and implemented properly. A program for increasing awareness and enhancing livelihood of the local populations be launched in the poor and poaching risk zones of Nepal.

  17. Waste water treatment plants as sources of polyfluorinated compounds, polybrominated diphenyl ethers and musk fragrances to ambient air

    International Nuclear Information System (INIS)

    Weinberg, Ingo; Dreyer, Annekatrin; Ebinghaus, Ralf

    2011-01-01

    To investigate waste water treatment plants (WWTPs) as sources of polyfluorinated compounds (PFCs), polybrominated diphenyl ethers (PBDEs) and synthetic musk fragrances to the atmosphere, air samples were simultaneously taken at two WWTPs and two reference sites using high volume samplers. Contaminants were accumulated on glass fiber filters and PUF/XAD-2/PUF cartridges, extracted compound-dependent by MTBE/acetone, methanol, or hexane/acetone and detected by GC-MS or HPLC-MS/MS. Total (gas + particle phase) concentrations ranged from 97 to 1004 pg m -3 (neutral PFCs), -3 (ionic PFCs), 5781 to 482,163 pg m -3 (musk fragrances) and -3 (PBDEs) and were usually higher at WWTPs than at corresponding reference sites, revealing that WWTPs can be regarded as sources of musk fragrances, PFCs and probably PBDEs to the atmosphere. Different concentrations at the two WWTPs indicated an influence of WWTP size or waste water origin on emitted contaminant amounts. - Waste water treatment plants can be regarded as sources of musk fragrances, polyfluorinated compounds (PFCs) and polybrominated diphenyl ethers (PBDEs) to the atmosphere

  18. Elon Musk, founder of SpaceX and PayPal, to speak on campus Feb. 21

    OpenAIRE

    Crumbley, Liz

    2006-01-01

    Elon Musk, founder and chief executive officer of Space Exploration Technologies Co. (SpaceX), will speak on his company's Falcon rocket series and the future of university space research on Tuesday, Feb. 21 at 7:30 p.m. in Virginia Tech's Burruss Hall Auditorium. The event is free and open to the public.

  19. CLOSED-LOOP STRIPPING ANALYSIS (CLSA) OF SYNTHETIC MUSK COMPOUNDS FROM FISH TISSUES WITH MEASUREMENT BY OC/MS/SIM

    Science.gov (United States)

    Synthetic musk compounds are used as inexpensive fragrance materials for the production of perfumes and as additives to soap, detergent, and shampoo. They have been found in surface water, fish tissues, and human breast milk. The ubiquity of this class of compounds in the env...

  20. Acoustic and thermodynamic properties of binary mixtures of 1-nonanol with o-xylene, m-xylene, p-xylene, ethylbenzene and mesitylene at T = (298.15 and 308.15) K

    International Nuclear Information System (INIS)

    Rani, Ruman; Bhatia, Subhash C.

    2013-01-01

    Highlights: ► The values of densities and speeds of sound were measured for the binary mixtures at 298.15 and 308.15 K. ► Maximum deviations in excess functions were observed for binary mixtures of 1-nonanol with p-xylene. ► Calculated excess and deviation functions were fitted to the Redlich–Kister polynomial. ► The results analysed in terms of molecular interactions and structural effects. -- Abstract: Densities, ρ, and speeds of sound, u, of binary liquid mixtures of 1-nonanol with o-xylene, m-xylene, p-xylene, ethylbenzene and mesitylene have been measured over the entire range of composition at T = (298.15 and 308.15) K and at atmospheric pressure. Using these results, the values of the excess molar volume, V E , isentropic compressibility, κ S , molar isentropic compressibility, K S,m , excess molar isentropic compressibility, K S,m E , deviations of the speed of sound, u D , and excess partial molar volume, V ¯ m,i E,0 , and excess partial molar isentropic compressibility, K ¯ m,i E,0 at infinite dilution, have been calculated. The calculated excess and deviation functions have been fitted to the Redlich–Kister polynomial equations and the results analysed in terms of molecular interactions

  1. Excess molar volumes and refractive indices of (methoxybenzene+benzene, or toluene, or o-xylene, or m-xylene, or p-xylene, or mesitylene) binary mixtures between T=(288.15 to 303.15)K

    International Nuclear Information System (INIS)

    Al-Kandary, Jasem A.; Al-Jimaz, Adel S.; Abdul-Latif, Abdul-Haq M.

    2006-01-01

    Densities ρ and refractive indices n D for (anisole+benzene, or toluene, or o-xylene, or m-xylene or p-xylene or mesitylene) binary mixtures over the entire range of mole fraction, at temperatures (288.15, 293.15, 298.15, and 303.15)K and atmospheric pressure, have been measured. The excess molar volume V E and molar refraction deviation ΔR m , have been calculated and fitted to the Redlich-Kister polynomial relation to estimate the binary coefficients and standard errors. The excess molar volumes are positive for (anisole+mesitylene) binary mixtures and negative for (anisole+benzene, or toluene, or xylene isomers) binary mixtures at various temperatures. Partial molar volumes V-bar i and partial excess molar volumes V-bar i E have been also derived from the experimental data. The calculated values have been used to explain the dependency of intermolecular interaction between the mixing components on the alkyl substitution on benzene ring

  2. Influence of pre-treatment process on matrix effect for the determination of musk fragrances in fish and mussel.

    Science.gov (United States)

    Vallecillos, Laura; Pocurull, Eva; Borrull, Francesc

    2015-03-01

    Musk compounds are widely used as fragrances in personal care products. On account of their widespread use and their low biodegradation, they can be found in environmental samples. In our study two extraction methodologies were compared and different clean-up strategies were also studied in order to develop a reliable analytical method, with minimum matrix effect and good detection limits, to determine synthetic musk fragrances- six polycyclic musks, three nitro musks and the degradation product of one polycyclic musk- in fish and mussel samples. The first extraction technique involves a QuEChERS extraction, a consolidate extraction methodology in the field of food analysis of growing interest over recent years, followed by a dispersive solid-phase extraction (dSPE) as clean-up strategy. The second extraction technique consists of a conventional pressurised liquid extraction (PLE) with dichloromethane and an in-cell clean-up to decrease the matrix effect and remove the undesired components(⁎)present in PLE extracts. Large volume injection (LVI) followed by gas chromatography-ion trap-tandem mass spectrometry (GC-IT-MS/MS) was chosen as the separation and detection technique. Validation parameters, such as method detection limits and method quantification limits were found at ng g(-1) levels for both fish and mussel matrices. Good levels of intra-day and inter-day repeatabilities were obtained analysing fish and mussel samples spiked at 50 ng g(-1) (d.w.) (n=5, RSDsmarket in Tarragona and fish samples from the Ebro River. The results showed the presence of galaxolide (2.97-18.04 ng g(-1) (d.w.)) and tonalide (1.17-8.42 ng g(-1) (d.w.)) in all the samples analysed, while the remaining polycyclic musks such as cashmeran, celestolide and phantolide, were only detected in some of the fish samples analysed. None of the samples analysed contained detectable traces of the nitro musks studied. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Membrane Materials and Technology for Xylene Isomers Separation and Isomerization via Pervaporation

    KAUST Repository

    Bilaus, Rakan

    2014-01-01

    technology’s high energy intensity has become a growing concern. Membrane separation technology is a potential low-energy alternative. Polymeric membranes were investigated in a pervaporation experiment to separate xylene isomers. Polymers of intrinsic

  4. Long-lasting neurobehavioral effects of prenatal exposure to xylene in rats

    DEFF Research Database (Denmark)

    Hass, Ulla; Lund, S. P.; Simonsen, L.

    1997-01-01

    The persistence of neurobehavioral effects in female rats (Mol:WIST) exposed to 500 ppm technical xylene (dimethylbenzene, GAS-no 1330-20-7) for 6 hours per day on days 7-20 of prenatal development was studied. The dose level was selected so as not to induce maternal toxicity or decreased viabili...... are planned to investigate whether neurobehavioral effects resulting from prenatal xylene exposure can interact with neurophysiological aging processes. (C) 1997 Inter Press, Inc....

  5. Subacute ethanol consumption reverses p-xylene-induced decreases in axonal transport

    Energy Technology Data Exchange (ETDEWEB)

    Padilla, S.; Lyerly, D.L.; Pope, C.N.

    1992-01-01

    Organic solvants, as a class, have been implicated as neurotoxic agents in humans and laboratory animals. The study was designed to assess the interaction between subacute ingestion of moderate levels of ethanol and the p-xylene-induced decreases in protein and glycoprotein synthesis and axonal transport in the rat optic system. The results indicated that animals maintained on 10% ethanol as a drinking liquid show less p-xylene-induced neurotoxicity than animals receiving no ethanol supplement.

  6. Ototoxicity in rats exposed to ethylbenzene and to two technical xylene vapours for 13 weeks

    Energy Technology Data Exchange (ETDEWEB)

    Gagnaire, Francois; Langlais, Cristina; Grossmann, Stephane; Wild, Pascal [Institut National de Recherche et de Securite, Departement Polluants et Sante, Vandoeuvre Cedex (France)

    2007-02-15

    Male Sprague-Dawley rats were exposed to ethylbenzene (200, 400, 600 and 800 ppm) and to two mixed xylenes (250, 500, 1,000 and 2,000 ppm total compounds) by inhalation, 6 h/day, 6 days/week for 13 weeks and sacrificed for morphological investigation 8 weeks after the end of exposure. Brainstem auditory-evoked responses were used to determine auditory thresholds at different frequencies. Ethylbenzene produced moderate to severe ototoxicity in rats exposed to the four concentrations studied. Increased thresholds were observed at 2, 4, 8 and 16 kHz in rats exposed to 400, 600 and 800 ppm ethylbenzene. Moderate to severe losses of outer hair cells of the organ of Corti occurred in animals exposed to the four concentrations studied. Exposure to both mixed xylenes produced ototoxicity characterized by increased auditory thresholds and losses of outer hair cells. Ototoxicity potentiation caused by ethylbenzene was observed. Depending on the mixed xylene studied and the area of the concentration-response curves taken into account, the concentrations of ethylbenzene in mixed xylenes necessary to cause a given ototoxicity were 1.7-2.8 times less than those of pure ethylbenzene. Given the high ototoxicity of ethylbenzene, the safety margin of less or equal to two (LOAEL/TWA) might be too small to protect workers from the potential risk of ototoxicity. Moreover, the enhanced ototoxicity of ethylbenzene and para-xylene observed in mixed xylenes should encourage the production of mixed xylenes with the lowest possible concentrations of ethylbenzene and para-xylene. (orig.)

  7. Ototoxicity in rats exposed to ethylbenzene and to two technical xylene vapours for 13 weeks.

    Science.gov (United States)

    Gagnaire, François; Langlais, Cristina; Grossmann, Stéphane; Wild, Pascal

    2007-02-01

    Male Sprague-Dawley rats were exposed to ethylbenzene (200, 400, 600 and 800 ppm) and to two mixed xylenes (250, 500, 1,000 and 2,000 ppm total compounds) by inhalation, 6 h/day, 6 days/week for 13 weeks and sacrificed for morphological investigation 8 weeks after the end of exposure. Brainstem auditory-evoked responses were used to determine auditory thresholds at different frequencies. Ethylbenzene produced moderate to severe ototoxicity in rats exposed to the four concentrations studied. Increased thresholds were observed at 2, 4, 8 and 16 kHz in rats exposed to 400, 600 and 800 ppm ethylbenzene. Moderate to severe losses of outer hair cells of the organ of Corti occurred in animals exposed to the four concentrations studied. Exposure to both mixed xylenes produced ototoxicity characterized by increased auditory thresholds and losses of outer hair cells. Ototoxicity potentiation caused by ethylbenzene was observed. Depending on the mixed xylene studied and the area of the concentration-response curves taken into account, the concentrations of ethylbenzene in mixed xylenes necessary to cause a given ototoxicity were 1.7-2.8 times less than those of pure ethylbenzene. Given the high ototoxicity of ethylbenzene, the safety margin of less or equal to two (LOAEL/TWA) might be too small to protect workers from the potential risk of ototoxicity. Moreover, the enhanced ototoxicity of ethylbenzene and para-xylene observed in mixed xylenes should encourage the production of mixed xylenes with the lowest possible concentrations of ethylbenzene and para-xylene.

  8. Fate of synthetic musks in a domestic wastewater treatment plant and in an agricultural field amended with biosolids

    International Nuclear Information System (INIS)

    Yang, J.-J.; Metcalfe, Chris D.

    2006-01-01

    Synthetic musks are widely used as fragrance ingredients in personal care products, and they enter domestic wastewater treatment plants (WWTPs) through discharges into municipal sewage systems. Samples of aqueous sewage and biosolids collected from the Peterborough Wastewater Treatment Plant (WWTP), Ontario, Canada were analyzed for 11 synthetic musk compounds using GC/MS. The results showed that 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethyl-cyclopenta[g]-2-benzopyrane (HHCB, 173.1 ± 43.4 ng/L) and 7-acetyl-1,1,3,4,4,6-hexamethyl-tetrahydronaphthalene (AHTN, 41.6 ± 15.8 ng/L) were the dominant fragrances in sewage, but other polycyclic musks and nitro musks were present at lower concentrations. The concentrations of HHCB and AHTN in the aqueous phase of the sewage were highly correlated with both BOD 5 and TOC. The overall removal efficiency of synthetic musks from the aqueous sewage in the WWTP ranged from 43.3% to 56.9%, but removal occurred mainly by partitioning into the biosolids. Based on a mass balance model, the daily input and output of HHCB and AHTN in the Peterborough WWTP were 47 g and 46 g, respectively. In an agricultural field amended with biosolids from the Peterborough WWTP, HHCB and AHTN were detected in soil immediately after application at mean concentrations of 1.0 and 1.3 μg/kg, respectively, but concentrations declined relatively rapidly over the next 6 weeks, post-application

  9. Measurement method for benzene, toluene, and xylene in the atmosphere by the gas chromatographic method

    Energy Technology Data Exchange (ETDEWEB)

    Shiroyama, H

    1975-08-01

    The chromatographic method for measuring benzene, toluene, and xylene (three isomers) in the atmosphere was evaluated using the Varian model 2740-10 gas chromatograph. As a solvent, n-hexane was most suitable, and the detection limit was improved by increasing the purity of n-hexane. The calibration curves were prepared, the recovery rate was calculated (76.0-99.4 percent), and the correlation coefficient was obtained from regression curves (r equals 0.97-0.99). Samples collected at a naphtha cracking plant, an aluminum smelting mill, a pharmaceutical plant, a carbon electrode manufacturing plant, a plywood manufacturing plant, a plastic bathtub manufacturing plant, and along a major highway were analyzed. All three substances were detected in all samples with the concentration of toluene high compared to the other two. Among xylene isomers, the concentration of p-xylene was always the lowest while m- and o-xylene varied from place to place. In the atmosphere along the highway, the benzene, toluene, and xylene determined were 0.01-0.09 ppM. No benzene, toluene, and xylene were detected in atmospheric samples used as controls.

  10. Sustainable Production of o-Xylene from Biomass-Derived Pinacol and Acrolein.

    Science.gov (United States)

    Hu, Yancheng; Li, Ning; Li, Guangyi; Wang, Aiqin; Cong, Yu; Wang, Xiaodong; Zhang, Tao

    2017-07-21

    o-Xylene (OX) is a large-volume commodity chemical that is conventionally produced from fossil fuels. In this study, an efficient and sustainable two-step route is used to produce OX from biomass-derived pinacol and acrolein. In the first step, the phosphotungstic acid (HPW)-catalyzed pinacol dehydration in 1-ethyl-3-methylimidazolium chloride ([emim]Cl) selectively affords 2,3-dimethylbutadiene. The high selectivity of this reaction can be ascribed to the H-bonding interaction between Cl - and the hydroxy group of pinacol. The stabilization of the carbocation intermediate by the surrounding anion Cl - may be another reason for the high selectivity. Notably, the good reusability of the HPW/[emim]Cl system can reduce the waste output and production cost. In the second step, OX is selectively produced by a Diels-Alder reaction of 2,3-dimethylbutadiene and acrolein, followed by a Pd/C-catalyzed decarbonylation/aromatization cascade in a one-pot fashion. The sustainable two-step process efficiently produces renewable OX in 79 % overall yield. Analogously, biomass-derived crotonaldehyde and pinacol can also serve as the feedstocks for the production of 1,2,4-trimethylbenzene. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Technetium-99m extraction and transport across tri-n-octylamine-xylene based supported liquid membranes

    International Nuclear Information System (INIS)

    Ashraf Chaudry, M.; Ahmad, B.

    1996-01-01

    The nuclear properties of 99m Tc radionuclide are ideal for organ imaging. Study of the technetium transport across supported liquid membranes has been performed to get data for its separation from other elements. Tri-n-octylamine diluted in xylene was used to constitute the liquid membranes, supported in polypropylene microporous films. Stripping on the product solution side was performed with dilute NaOH solutions. The effect of sulphuric acid, nitric acid and hydrochloric acid in the feed on transport of 99m Tc as TcO 4 - ions has been studied. The permeability of the given ions determined from kinetic activity data has been found to be in the order of PH 2 SO 4 >PHCl>PHNO 3 . The flux values have been calculated based on this permeability data. The increase in carrier concentration has shown an increase in flux and permeability values to a given optimum concentration. The increase in temperature has been found to reduce the transport of Tc ions. The optimum conditions for transport of 99m Tc for the given acid concentration have been determined. Mechanism of Tc ion transport has also been provided based on chemical reactions involved at the membrane interfaces and uptake of Tc ions by the membrane. MoO 4 2- ions do not permeate through membrane under optimum conditions of transport for TcO 4 2 - ions from H 2 SO 4 solution. (author). 12 refs., 20 figs., 1 tab

  12. The investigation of exposure to benzene, toluene, ethylbenzene and xylene (BTEX with Solid Phase Microextr action Method in gas station in Yazd province

    Directory of Open Access Journals (Sweden)

    Mohammad Hossein Mosaddegh Mehrjerdi

    2014-01-01

    Full Text Available Abstract Background: Benzene, toluene, ethylbenzene and xylene (BTEX are volatile organic compounds which their physical and chemical characteristics are similar. Evaporation of BTEX from gasoline in petrol station into the air causes gasoline station attendants expose to them. A new extraction method of volatile organic compounds is solid phase microextraction (SPME. The aim of this study is to optimize extraction conditions of BTEX from air samples and then determination of gasoline station air contamination with BTEX in Yazd. Material and Methods: In this study air samples were collected using Tedlar bags and then extracted and analyzed with SPME fiber and gas chromatography equipped with a flame ionization detector. Results: Our results indicate that PDMS/CAR has the best peak area in comparison with two other fibers The Optimized extraction and desorption times are estimated 3 and 1 minutes, respectively Mean concentration of benzene, toluene, ethyl benzene and xylene in gas station’s air were 1932±807, 667±405, 148±89, 340±216 µg/m3 respectively. Conclusion: Benzene mean concentration is above threshold limit value (0.5PPM. Whereas, toluene, ethylbenzene and xylene mean concentration are lower than threshold limit values.

  13. Duchenne Musküler Distrofili Bir Olguda Anestezi Yönetimi

    OpenAIRE

    KARAHAN, N.; AKSUN, M.; KOROĞLU, L.; GİRGİN, S.; ARAN, G.; AKHAN, G.; GÜRBÜZ, A.

    2014-01-01

    Duchenne Musküler Distrofi (DMD); X’e bağlı resesif olarak geçiş gösteren ilerleyici kas zayıflığı ve kas kontraktürleri ile karakterize kalıtımsal bir hastalıktır. En sık çocukluk yaşlarında ve 3.500 erkek doğumda 1 görülmektedir. Bu hastalarda anestezi yönetimi özellik göstermektedir. Çünkü inhalasyon anestezikleri ve süksinilkolin gibi ajanlar, hipermetabolik bir klinik tablo ile seyreden malign hipertermi gibi ölümcül komplikasyonlara yol açabilir. Biz ventriküler septal defekt (VSD) nede...

  14. Sex differences in the toxicokinetics of inhaled solvent vaporsin humans 1. m-Xylene

    International Nuclear Information System (INIS)

    Ernstgaard, Lena; Sjoegren, Bengt; Warholm, Margareta; Johanson, Gunnar

    2003-01-01

    The aim of this study was to evaluate possible sex differences in the inhalation toxicokinetics of m-xylene vapor. Seventeen healthy volunteers (nine women and eight men) were exposed to m-xylene (200 mg/m 3 ) and to clean air (control exposure) on different occasions during 2 h of light physical exercise (50 W). The chosen level corresponds to the occupational exposure limit (8-h time weighted average) in Sweden. m-Xylene was monitored up to 24 h after exposure in exhaled air, blood, saliva, and urine by headspace gas chromatography. m-Methylhippuric acid (a metabolite of m-xylene) was analyzed in urine by high-performance liquid chromatography. Body fat and lean body mass (LBM) were estimated from sex-specific equations using bioelectrical impedance, body weight, height, and age. Genotypes and/or phenotypes of cytochromes P450 2E1 and 1A1, glutathione transferases M1 and P1, and epoxide hydrolase were determined. The toxicokinetic profile in blood was analyzed using a two-compartment population model. The area under the concentration-time curve (AUC) of m-xylene in exhaled air postexposure was larger in women than in men. In addition, the excretion via exhaled air was significantly higher in women when correcting for body weight or LBM. In contrast, the men had a significantly higher volume of distribution, excretion of m-methylhippuric acid in urine, and AUC of m-xylene in urine. The toxicokinetic analyses revealed no differences between subjects of different metabolic genotypes or phenotypes. In conclusion, the study indicates small sex differences in the inhalation toxicokinetics of m-xylene, which can be explained by body build

  15. High Selectively Catalytic Conversion of Lignin-Based Phenols into para-/m-Xylene over Pt/HZSM-5

    Directory of Open Access Journals (Sweden)

    Guozhu Liu

    2016-01-01

    Full Text Available High selectively catalytic conversion of lignin-based phenols (m-cresol, p-cresol, and guaiacol into para-/m-xylene was performed over Pt/HZSM-5 through hydrodeoxygenation and in situ methylation with methanol. It is found that the p-/m-xylene selectivity is uniformly higher than 21%, and even increase up to 33.5% for m-cresol (with phenols/methanol molar ratio of 1/8. The improved p-/m-xylene selectivity in presence of methanol is attributed to the combined reaction pathways: methylation of m-cresol into xylenols followed by HDO into p-/m-xylene, and HDO of m-cresol into toluene followed by methylation into p-/m-xylene. Comparison of the product distribution over a series of catalysts indicates that both metals and supporters have distinct effect on the p-/m-xylene selectivity.

  16. Theoretical study on the alkylation of o-xylene with styrene in AlCl3-ionic liquid catalytic system.

    Science.gov (United States)

    Cao, Bobo; Du, Jiuyao; Cao, Ziping; Sun, Haitao; Sun, Xuejun; Fu, Hui

    2017-06-01

    To explore sustainable catalysts with innovative mechanisms, the alkylation mechanism of o-xylene with styrene was studied using DFT method in AlCl 3 -ionic liquid catalytic system. The reaction pathway was consisted of CC coupling and a hydrogen shift, in which two transition states were found and further discussed. The reactive energy catalyzed by superelectrophilic AlCl 2 + (12.6kcal/mol) was distinctly lower than AlCl 3 (43.0kcal/mol), which was determined as the rate-determining step. Mulliken charge along IRC gave a comprehensive understanding of charge distribution and electron transfer in dynamic progress. Bond orders and AIM theory were used to study the nature of chemical bonds and the driving forces in different reaction stages. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. High dimension feature extraction based visualized SOM fault diagnosis method and its application in p-xylene oxidation process☆

    Institute of Scientific and Technical Information of China (English)

    Ying Tian; Wenli Du; Feng Qian

    2015-01-01

    Purified terephthalic acid (PTA) is an important chemical raw material. P-xylene (PX) is transformed to terephthalic acid (TA) through oxidation process and TA is refined to produce PTA. The PX oxidation reaction is a complex process involving three-phase reaction of gas, liquid and solid. To monitor the process and to im-prove the product quality, as wel as to visualize the fault type clearly, a fault diagnosis method based on self-organizing map (SOM) and high dimensional feature extraction method, local tangent space alignment (LTSA), is proposed. In this method, LTSA can reduce the dimension and keep the topology information simultaneously, and SOM distinguishes various states on the output map. Monitoring results of PX oxidation reaction process in-dicate that the LTSA–SOM can wel detect and visualize the fault type.

  18. Volumetric, Viscometric and Excess Properties of Binary Mixtures of 1-Iodobutane with Benzene, Toluene, o-Xylene, m-Xylene, p-Xylene, and Mesitylene at Temperatures from 303.15 to 313.15 K

    Directory of Open Access Journals (Sweden)

    Sangita Sharma

    2013-01-01

    Full Text Available Densities and viscosities have been determined for binary mixtures of 1-iodobutane with benzene, toluene, o-xylene, m-xylene, p-xylene, and mesitylene at 303.15, 308.15, and 313.15 K for the entire composition range at atmospheric pressure. The excess molar volumes, , deviations in viscosity, Δη, and excess Gibbs’ free energy of activation flow, Δ have been calculated from the experimental values. The experimental data were fitted to Redlich-Kister polynomial equation. The variations of these parameters with composition of the mixtures and temperature have been discussed in terms of molecular interactions occurring in these mixtures. Further, the viscosities of these binary mixtures were calculated theoretically from their corresponding pure component data by using empirical relations like Bingham, Arrhenius and Eyring, Kendall and Munroe, Hind, Katti and Chaudhari, Grunberg and Nissan, and Tamura and Kurata. Comparison of various interaction parameters has been expressed to explain the intermolecular interactions between iodobutane and selected hydrocarbons.

  19. 78 FR 35922 - Endocrine Disruptor Screening Program; Final Second List of Chemicals and Substances for Tier 1...

    Science.gov (United States)

    2013-06-14

    ... health or the environment due to disruption of the endocrine system. The determination that a chemical... chemicals (e.g., triclosan, alkylphenols and alkylphenol polyethoxylates, bisphenol A, musk fragrances, and..., methanol, and perchlorate) can occur naturally in the environment, this is not the only known pathway of...

  20. Estimation of body surface area in the musk shrew ( Suncus murinus): a small animal for testing chemotherapy-induced emesis.

    Science.gov (United States)

    Eiseman, Julie L; Sciullo, Michael; Wang, Hong; Beumer, Jan H; Horn, Charles C

    2017-10-01

    Several cancer chemotherapies cause nausea and vomiting, which can be dose-limiting. Musk shrews are used as preclinical models for chemotherapy-induced emesis and for antiemetic effectiveness. Unlike rats and mice, shrews possess a vomiting reflex and demonstrate an emetic profile similar to humans, including acute and delayed phases. As with most animals, dosing of shrews is based on body weight, while translation of such doses to clinically equivalent exposure requires doses based on body surface area. In the current study body surface area in musk shrews was directly assessed to determine the Meeh constant (K m ) conversion factor (female = 9.97, male = 9.10), allowing estimation of body surface area based on body weight. These parameters can be used to determine dosing strategies for shrew studies that model human drug exposures, particularly for investigating the emetic liability of cancer chemotherapeutic agents.

  1. Occurrence, profile and spatial distribution of UV-filters and musk fragrances in mussels from Portuguese coastline.

    Science.gov (United States)

    Castro, M; Fernandes, J O; Pena, A; Cunha, S C

    2018-07-01

    The increasing production and consumption of Personal Care Products (PCPs), containing UV-filters and musk fragrances, has led to its widespread presence in the aquatic environment which can cause harmful effects to the aquatic organisms due to its intrinsic toxicity. This study aims to evaluate the degree of contamination of wild mussels along the entire Portuguese coastline, continually exposed in their habitat to different contaminants. For this purpose, approximately 1000 mussel specimens were sampled during one year in seven different locations, along the Portuguese coastline. Simultaneous quantification of five UV-filters and seven musks in mussels was achieved by a Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) extraction procedure combined with dispersive liquid-liquid microextraction (DLLME) followed by gas chromatography with mass spectrometry (GC-MS) analysis. Ten out of the twelve target analytes were found in the analysed samples, highlighting the presence of AHTN (tonalide), EHS (2-ethylhexylsalicylate) and EHMC (2-ethylhexyl 4-methoxycinnamate) in all positive samples (93%). Overall, the results obtained indicate a widespread contamination of wild mussels along Portuguese coastline, all over the year. UV-filters were more frequently detected (90%) than musk fragrances (70%) and also quantified at higher levels, with average total concentrations reaching 1155.8 ng/g (dw) against 397.7 ng/g (dw) respectively. A high correlation was observed between the most densely populated and industrialized locations and the higher levels of musks and UV-filters found. In other hand, lower levels of PCPs were found in protected areas. As expected, an increase in UV-filters levels was observed after the summer, likely due to the intense period of recreational activities. Copyright © 2018 Elsevier Ltd. All rights reserved.

  2. UV-filters and musk fragrances in seafood commercialized in Europe Union: Occurrence, risk and exposure assessment.

    Science.gov (United States)

    Cunha, S C; Trabalón, L; Jacobs, S; Castro, M; Fernandez-Tejedor, M; Granby, K; Verbeke, W; Kwadijk, C; Ferrari, F; Robbens, J; Sioen, I; Pocurull, E; Marques, A; Fernandes, J O; Domingo, J L

    2018-02-01

    In the framework of the FP7 ECsafeSeafood project, 62 seafood samples commercialized in Europe Union from several representative species - mackerel, tuna, salmon, seabream, cod, monkfish, crab, shrimp, octopus, perch and plaice - were analysed for residues of 21 personal care products (PCPs), including 11 UV-filters (UV-Fs) and 10 musk fragrances (musks). PCPs analysis were performed by Quick, Easy, Cheap, Effective Rugged, Safe (QuEChERS), combined with liquid-liquid extraction (LLE) or dispersive solid-phase extraction (dSPE), followed by gas chromatography-tandem mass spectrometry (GC-MS/MS). The results showed the presence in a wide range of samples of nine out of eleven UV-Fs compounds analysed, namely 2-ethylhexyl salicylate (EHS), 2-ethylhexyl,4-methoxycinnamate (EHMC), 4-methylbenzylidenecamphor (4-MBC), benzophenone-1 (BP1), benzophenone-3 (BP3), isoamyl-4-methoxycinnamate (IMC), 2,2'-dihydroxy-4,4'-dimethoxybenzophenone (DHMB), homosalate (HS), and octocrylene (OC), whereas galaxolide (HHCB), galaxolide lactone (HHCB-lactone), and tonalide (AHTN) were the most found musks. The potential risks to human health associated with the exposure to eight of the more prevalent PCPs - EHS, EHMC, 4-MBC, BP1, BP3, IMC, HHCB, and AHTN - through seafood consumption were assessed for consumers from five European countries (Belgium, Ireland, Italy, Portugal and Spain). Results showed that the human exposure to UV-Fs and musks estimated from the concentration values found in seafood and the daily consumption of concerned seafood species, were far below toxicological reference values. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Acute toxicity of toluene, hexane, xylene, and benzene to the rotifers Brachionus calyciflorus and Brachionus plicatilis

    Energy Technology Data Exchange (ETDEWEB)

    Ferrando, M.D.; Andreu-Moliner, E. (Univ. of Valencia (Spain))

    1992-08-01

    A large number of studies on the biological effects of oil pollution in the aquatic environment deal with the effects of whole crude or refined oils or their water-soluble fractions. However, low boiling, aromatic hydrocarbons, which are probably the most toxic constituents of oil, have until now not been examined in sufficient detail. Toluene, benzene and xylene, constitute a major component of various oils. They may be readily lost by weathering but are toxic in waters that are relatively stagnant and are chronically polluted. Korn et al. have stated that toluene is more toxic than many other hydrocarbons such as benzene, though the latter are more water-soluble. Report of the effects of exposure to organic solvents like hexane or toluene are still limited although organic solvents are a well-known group of neurointoxicants. Various benzene derivates continue to be used as chemical intermediates, solvents, pesticides, so on, in spite of incomplete knowledge of their chronic toxicity. The majority of toxicity studies about the effects of pollution on aquatic organisms under controlled conditions have used either fish or the cladoceran Daphnia magna and there are few studies reported using rotifers. The effects of herbicides on population variables of laboratory rotifer cultures have been investigated. Rotifers are one of the main sources of zooplankton production and they have an important ecological significance in the aquatic environment. The present work was designed to investigate the effect of short-term exposure to some petroleum derivates which might be expected to occur immediately under an oil-slick, on freshwater and brackish environment rotifers. 18 refs., 1 tab.

  4. In-Vial Micro-Matrix-Solid Phase Dispersion for the Analysis of Fragrance Allergens, Preservatives, Plasticizers, and Musks in Cosmetics

    Directory of Open Access Journals (Sweden)

    Maria Celeiro

    2014-07-01

    Full Text Available Fragrance allergens, preservatives, plasticizers, and synthetic musks are usually present in cosmetic and personal care products formulations and many of them are subjected to use restrictions or labeling requirements. Matrix solid-phase dispersion (MSPD is a very suitable analytical technique for the extraction of these compounds providing a simple, low cost sample preparation, and the possibility of performing both extraction and clean-up in one step, reducing possible contamination and analyte losses. This extraction technique has been successfully applied to many cosmetics ingredients allowing obtaining quantitative recoveries. A new very simple micro-MSPD procedure performing the disruption step in a vial is proposed for the gas chromatography-mass spectrometry (GC-MS analysis of 66 chemicals usually present in cosmetics and personal care products. The method was validated showing general recoveries between 80% and 110%, relative standard deviation (RSD values lower than 15%, and limits of detection (LODs below 30 ng·g−1. The validated method was applied to a broad range of cosmetics and personal care products, including several products intended for baby care.

  5. Sustainable hydrogen production from bio-oil model compounds (meta-xylene) and mixtures (1-butanol, meta-xylene and furfural).

    Science.gov (United States)

    Bizkarra, K; Barrio, V L; Arias, P L; Cambra, J F

    2016-09-01

    In the present work m-xylene and an equimolecular mixture of m-xylene, 1-butanol and furfural, all of them bio-oil model compounds, were studied in steam reforming (SR) conditions. Three different nickel catalysts, which showed to be active in 1-butanol SR (Ni/Al2O3, Ni/CeO2-Al2O3 and Ni/La2O3-Al2O3), were tested and compared with thermodynamic equilibrium values. Tests were carried out at temperatures from 800 to 600°C at atmospheric pressure with a steam to carbon ratio (S/C) of 5.0. Despite the different bio-oils fed, the amount of moles going through the catalytic bed was kept constant in order to obtain comparable results. After their use, catalysts were characterized by different techniques and those values were correlated with the activity results. All catalysts were deactivated during the SR of the mixture, mainly by coking. The highest hydrogen yields were obtained with Ni/Al2O3 and Ni/CeO2-Al2O3 catalysts in the SR of m-xylene and SR of the mixture, respectively. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Fixed-bed adsorption separation of xylene isomers over sio2/silicallite-1 core-shell adsorbents

    KAUST Repository

    Khan, Easir A.; Rajendran, Arvind; Lai, Zhiping

    2013-01-01

    SiO2/Silicalite-1 core-shell material has been demonstrated as potential shape selective adsorbent in gas phase separation of p-xylene from a mixture of p/o-xylene isomers. The core-shell composite comprised of large silica core and thin

  7. Effects of casting and post casting annealing on xylene isomer transport properties of Torlon® 4000T films

    KAUST Repository

    Chafin, Raymond; Lee, Jong Suk; Koros, William J.

    2010-01-01

    Procedures for Torlon® 4000T membrane formation were developed to provide attractive and repeatable xylene separation properties. Torlon® 4000T membrane films cast by our method were investigated in terms of thermally induced imidization, molecular weight enhancement, and solvent removal. After development of the Torlon® 4000T casting procedure, pervaporation of a xylene mixture (i.e. 30% para-xylene, 30% meta-xylene, 30% ortho-xylene, and 10% ethylbenzene) was performed in both Torlon® 4000T and post casting annealed Torlon® 4000T films. The xylene pervaporation in annealed Torlon® 4000T film at 200°C gave a permeability of 0.25 Barrer and a selectivity of 3.1 (para/ortho) and 2.1 (para/meta) respectively. A so-called " permeability collapse" reflecting an accelerated reduction in the free volume is consistent with significant temperature-induced changes in the films observed after thermal annealing at 300°C. This conditioning effect is induced by a combination of heat treatment and the presence of the interacting aromatic penetrants. Optical methods were used to verify that the density of annealed samples exposed to xylene for 5 days eventually increased, suggesting that the membrane is originally swollen upon initial xylene exposure, and then relaxes to a more densified, and more discriminating state. © 2010 Elsevier Ltd.

  8. Effects of casting and post casting annealing on xylene isomer transport properties of Torlon® 4000T films

    KAUST Repository

    Chafin, Raymond

    2010-07-01

    Procedures for Torlon® 4000T membrane formation were developed to provide attractive and repeatable xylene separation properties. Torlon® 4000T membrane films cast by our method were investigated in terms of thermally induced imidization, molecular weight enhancement, and solvent removal. After development of the Torlon® 4000T casting procedure, pervaporation of a xylene mixture (i.e. 30% para-xylene, 30% meta-xylene, 30% ortho-xylene, and 10% ethylbenzene) was performed in both Torlon® 4000T and post casting annealed Torlon® 4000T films. The xylene pervaporation in annealed Torlon® 4000T film at 200°C gave a permeability of 0.25 Barrer and a selectivity of 3.1 (para/ortho) and 2.1 (para/meta) respectively. A so-called " permeability collapse" reflecting an accelerated reduction in the free volume is consistent with significant temperature-induced changes in the films observed after thermal annealing at 300°C. This conditioning effect is induced by a combination of heat treatment and the presence of the interacting aromatic penetrants. Optical methods were used to verify that the density of annealed samples exposed to xylene for 5 days eventually increased, suggesting that the membrane is originally swollen upon initial xylene exposure, and then relaxes to a more densified, and more discriminating state. © 2010 Elsevier Ltd.

  9. Fixed-bed adsorption separation of xylene isomers over sio2/silicallite-1 core-shell adsorbents

    KAUST Repository

    Khan, Easir A.

    2013-12-29

    SiO2/Silicalite-1 core-shell material has been demonstrated as potential shape selective adsorbent in gas phase separation of p-xylene from a mixture of p/o-xylene isomers. The core-shell composite comprised of large silica core and thin polycrystalline silicalite-1 shell which was synthesized via a self-assembly of silicalite-1 nanocrystals on core silica surface followed by a secondary seeded growth method. The core materials, SiO2 used in this study has mesoporosity with an average pore diameter of 60Å and hence offers no shape selectivity for xylene isomers. However, the shell, silicalite-1 contains rigid pore structures and preferentially adsorbs p-xylene from their isomers mixtures. A series of adsorption fixed bed breakthrough adsorption/desorption experiment was performed to obtain the equilibrium isotherms and adsorption isotherm parameters of xylene isomers. The equilibrium isotherms of xylene isomers follow the Langmuir\\'s model. A chromatographic adsorption model has been used to describe the fixed-bed breakthrough profiles of xylene isomers. The model has successfully predicted the responses of the binary mixtures of p/o-xylene isomers. The SiO2/silicalite-1 core-shell adsorbents have shown para-selectivity as high as 15. © Bangladesh Uni. of Engg. & Tech.

  10. Assessing ecorelevance of emerging chemicals in sediments

    DEFF Research Database (Denmark)

    Forbes, Valery E.; Selck, Henriette; Salvito, D.

    2007-01-01

    Environmental monitoring of the Great Lakes and elsewhere has detected the presence of a wide variety of chemicals which has raised concern that these chemicals pose risks to resident species. Sediments are of particular interest due to their tendency to accumulate hydrophobic and persistent...... chemicals and because less is known about toxic effects of chemicals to sediment-feeding organisms than to pelagic species. Data collected on the polycyclic musks provides available evidence relevant to assessing exposure and effects in Great Lakes' sediments. Studies at Roskilde University demonstrate how...

  11. POLLUTION PREVENTION OPPORTUNITY ASSESSMENT HISTOLOGY LABORATORY XYLENE USE - FORT CARSON, COLORADO

    Science.gov (United States)

    Under the WREAFS program, RREL has performed a waste minimization opportunity assessment (WMOA) at the Evans Community Hospital Histopathology Laboratory on the Ft. Carson Army Base, Colorado, in the area of waste xylene and ethyl alcohol contaminated with human tissue. The waste...

  12. Neonatal DHT but not E2 speeds induction of sexual receptivity in the musk shrew.

    Science.gov (United States)

    Ewton, Tiffany A; Siboni, Ruth B; Jackson, Andrea; Freeman, Louise M

    2010-06-01

    Neural aromatization of testosterone (T) to estrogen during development is thought to be important for sexual differentiation of many altricial mammals. We evaluated the effects of neonatal injections of the non-aromatizable androgen dihydrotestosterone propionate (DHTP) and estradiol (E2) on the copulatory behavior of the female musk shrew, an altricial insectivore. Following adult ovariectomy and replacement T, animals were paired with a stimulus female for two 60-minute copulatory behavior tests. The latency to induce sexual receptivity (in the form of tail-wagging by the female), mount latency and total number of mounts were recorded in experimental females and in a group of untreated control males. While neither hormone treatment significantly affected mounting behavior, DHTP-treated animals induced receptivity faster and with latencies not significantly different from intact males, suggesting that early non-aromatizable androgens can have masculinizing actions by either increasing sexual motivation or making the treated animal more attractive to the stimulus female. Reliance on androgenic rather than estrogenic metabolites for the differentiation of courtship behaviors conforms to the pattern seen more typically in primates than rodents. Copyright 2009 Elsevier Inc. All rights reserved.

  13. Quantum Calculation for Musk Molecules Infrared Spectra towards the Understanding of Odor

    Directory of Open Access Journals (Sweden)

    Elaine Rose Maia

    2014-01-01

    Full Text Available It is not clear so far how humans can recognize odor. One of the theories regarding structure-odor relationship is vibrational theory, which claims that odors can be recognized by their modes of vibration. In this sense, this paper brings a novel comparison made between musky and nonmusky molecules, as to check the existence of correlation between their modes on the infrared spectra and odor. For this purpose, sixteen musky odorants were chosen, as well as seven other molecules that are structurally similar to them, but with no musk odor. All of them were submitted to solid theoretical methodology (using molecular mechanics/molecular dynamics and Neglect of Diatomic Differential Overlap Austin Model 1 methods to optimize geometries as to achieve density functional theory spectra information, with both Gradient Corrected Functional Perdew-Wang generalized-gradient approximation (GGA/PW91 and hybrid Becke, three-parameter, Lee-Yang-Parr (B3LYP functional. For a proper analysis over spectral data, a mathematical method was designed, generating weighted averages for theoretical frequencies and computing deviations from these averages. It was then devised that musky odorants satisfied demands of the vibrational theory, while nonmusk compounds belonging either to nitro group or to acyclic group failed to fulfill the same criteria.

  14. Air-sea exchange fluxes of synthetic polycyclic musks in the North Sea and the Arctic.

    Science.gov (United States)

    Xie, Zhiyong; Ebinghaus, Ralf; Temme, Christian; Heemken, Olaf; Ruck, Wolfgang

    2007-08-15

    Synthetic polycyclic musk fragrances Galaxolide (HHCB) and Tonalide (AHTN) were measured simultaneously in air and seawater in the Arctic and the North Sea and in the rural air of northern Germany. Median concentrations of gas-phase HHCB and AHTN were 4 and 18 pg m(-3) in the Arctic, 28 and 18 pg m(-3) in the North Sea, and 71 and 21 pg m(-3) in northern Germany, respectively. Various ratios of HHCB/AHTN implied that HHCB is quickly removed by atmospheric degradation, while AHTN is relatively persistent in the atmosphere. Dissolved concentrations ranged from 12 to 2030 pg L(-1) for HHCB and from below the method detection limit (3 pg L(-1)) to 965 pg L(-1) for AHTN with median values of 59 and 23 pg L(-1), respectively. The medians of volatilization fluxes for HHCB and AHTN were 27.2 and 14.2 ng m(-2) day(-1) and the depositional fluxes were 5.9 and 3.3 ng m(-2) day(-1), respectively, indicating water-to-air volatilization is a significant process to eliminate HHCB and AHTN from the North Sea. In the Arctic, deposition fluxes dominated the air-sea gas exchange of HHCB and AHTN, suggesting atmospheric input controls the levels of HHCB and AHTN in the polar region.

  15. Action of Bacopa monnieri to antagonize cisplatin-induced emesis in Suncus murinus (house musk shrew

    Directory of Open Access Journals (Sweden)

    Ihsan Ullah

    2017-04-01

    Full Text Available Bacopa monnieri (BM, family Scrophulariaceae is used in several traditional systems of medicine for the management of epilepsy, depression, neuropathic pain, sleep disorders and memory deficits. The present study investigated the potential of BM methanol (BM-MetFr and BM n-butanol fractions (BM-ButFr to reduce chemotherapy-induced emesis in Suncus murinus (house musk shrew. Cisplatin (30 mg/kg, i.p. reliably induced retching and/or vomiting over a 2 day period. BM-MetFr (10–40 mg/kg, s.c. and BM-ButFr (5–20 mg/kg, s.c. antagonized the retching and/or vomiting response by ∼59.4% (p  0.05. In conclusion, the n-butanol fractions of BM have anti-emetic activity comparable with palonosetron and MPG. BM may be useful alone or in combination with other anti-emetic drugs for the treatment of chemotherapy-induced emesis in man.

  16. Conditioned flavor preference and the US postexposure effect in the house musk shrew (Suncus murinus

    Directory of Open Access Journals (Sweden)

    Kosuke eSawa

    2012-07-01

    Full Text Available The house musk shrew (Suncus murinus is the only species of insectivore that can be used as a laboratory animal and is an interesting subject in terms of evolutional and comparative aspects. The present study on the learning faculties of shrews examines the possibility of acquiring a conditioned flavor preference and the effects of US postexposure. Subjects were allowed to a drink sucrose solution with flavor A and tap water with flavor B during training. Two extinction tests were administered after every four conditioning trials, and a significant preference for flavor A was observed. After each test, the animals were divided into two groups. Subjects in Group US were presented with a sucrose solution without flavor, while those in Group Water were given tap water. After these trials, all subjects received choice tests where they were presented with water containing the two flavors. The preference ratio was lower in Group US than in Group Water, suggesting a postexposure effect. The findings were discussed in terms of habituation to the US.

  17. Effects of p-xylene inhalation on axonal transport in the rat retinal ganglion cells

    Energy Technology Data Exchange (ETDEWEB)

    Padilla, S.S.; Lyerly, D.P. (Environmental Protection Agency, Research Triangle Park, NC (USA))

    1989-12-01

    Although the solvent xylene is suspected of producing nervous system dysfunction in animals and humans, little is known regarding the neurochemical consequences of xylene inhalation. The intent of this study was to determine the effect of intermittent, acute, and subchronic p-xylene exposure on the axonal transport of proteins and glycoproteins within the rat retinofugal tract. A number of different exposure regimens were tested ranging from 50 ppm for a single 6-hr exposure to 1600 ppm 6 hr/day, 5 days/week, for a total of 8 exposure days. Immediately following removal from the inhalation chambers rats were injected intraocularly with (35S)methionine and (3H)fucose (to label retinal proteins and glycoproteins, respectively) and the axonal transport of labeled macromolecules to axons (optic nerve and optic tract) and nerve endings (lateral geniculate body and superior colliculus) was examined 20 hr after precursor injection. Only relatively severe exposure regimens (i.e., 800 or 1600 ppm 6 hr/day, 5 days/week, for 1.5 weeks) produced significant reductions in axonal transport; there was a moderate reduction in the axonal transport of 35S-labeled proteins in the 800-ppm-treated group which was more widespread in the 1600 ppm-treated group. Transport of 3H-labeled glycoproteins was less affected. Assessment of retinal metabolism immediately after isotope injection indicated that the rate of precursor uptake was not reduced in either treatment group. Furthermore, rapid transport was still substantially reduced in animals exposed to 1600 ppm p-xylene and allowed a 13-day withdrawal period. These data indicate that p-xylene inhalation decreases rapid axonal transport supplied to the projections of the rat retinal ganglion cells immediately after cessation of inhalation exposure and that this decreased transport is still apparent 13 days after the last exposure.

  18. Effects of p-xylene inhalation on axonal transport in the rat retinal ganglion cells

    International Nuclear Information System (INIS)

    Padilla, S.S.; Lyerly, D.P.

    1989-01-01

    Although the solvent xylene is suspected of producing nervous system dysfunction in animals and humans, little is known regarding the neurochemical consequences of xylene inhalation. The intent of this study was to determine the effect of intermittent, acute, and subchronic p-xylene exposure on the axonal transport of proteins and glycoproteins within the rat retinofugal tract. A number of different exposure regimens were tested ranging from 50 ppm for a single 6-hr exposure to 1600 ppm 6 hr/day, 5 days/week, for a total of 8 exposure days. Immediately following removal from the inhalation chambers rats were injected intraocularly with [35S]methionine and [3H]fucose (to label retinal proteins and glycoproteins, respectively) and the axonal transport of labeled macromolecules to axons (optic nerve and optic tract) and nerve endings (lateral geniculate body and superior colliculus) was examined 20 hr after precursor injection. Only relatively severe exposure regimens (i.e., 800 or 1600 ppm 6 hr/day, 5 days/week, for 1.5 weeks) produced significant reductions in axonal transport; there was a moderate reduction in the axonal transport of 35S-labeled proteins in the 800-ppm-treated group which was more widespread in the 1600 ppm-treated group. Transport of 3H-labeled glycoproteins was less affected. Assessment of retinal metabolism immediately after isotope injection indicated that the rate of precursor uptake was not reduced in either treatment group. Furthermore, rapid transport was still substantially reduced in animals exposed to 1600 ppm p-xylene and allowed a 13-day withdrawal period. These data indicate that p-xylene inhalation decreases rapid axonal transport supplied to the projections of the rat retinal ganglion cells immediately after cessation of inhalation exposure and that this decreased transport is still apparent 13 days after the last exposure

  19. Determination of musks and other fragrance compounds at ng/L levels using CLSA (closed loop stripping analysis) and GC/MS detection.

    Science.gov (United States)

    Mitjans, D; Ventura, F

    2004-01-01

    Closed loop stripping analysis (CLSA), a suitable tool for the determination of volatile and semivolatile compounds at low trace levels (ng/l), has been used to determine and quantify seven selected musks and two fragrances (Acetyl cedrene and Amberonne). The obtained extracts are analyzed by high resolution gas chromatography coupled to mass spectrometry (GC/MS) operating in the SIM mode. Quality parameters such as limit of detection; matrix effects; precision expressed as repeatability and reproducibility relative standard deviations of the method and an estimation of the uncertainty have been evaluated. The method has been applied to the analysis of wastewater effluents, surface water and tap water from different places in Europe. All samples contained differents musks at ng/l levels with the polycyclic musks Galaxolide and Tonalide and both fragrances, Amberonne and Acetyl cedrene, being the most abundant. These results suggest the importance of studying and controlling the presence of these ubiquitous environmental compounds in water systems.

  20. Ancient DNA analyses exclude humans as the driving force behind late Pleistocene musk ox (Ovibos moschatus) population dynamics

    DEFF Research Database (Denmark)

    Campos, Paula; Willerslev, Eske; Sher, Andrei

    2010-01-01

    The causes of the late Pleistocene megafaunal extinctions are poorly understood. Different lines of evidence point to climate change, the arrival of humans, or a combination of these events as the trigger. Although many species went extinct, others, such as caribou and bison, survived......, as it was the geographic origin of all samples studied and held a large diverse population until local extinction at approximately 45,000 radiocarbon years before present ((14)C YBP). Subsequently, musk ox genetic diversity reincreased at ca. 30,000 (14)C YBP, recontracted at ca. 18,000 (14)C YBP, and finally recovered...

  1. Behavioral patterns associated with chemotherapy-induced emesis: A potential signature for nausea in musk shrews

    Directory of Open Access Journals (Sweden)

    Charles Christopher Horn

    2011-07-01

    Full Text Available Nausea and vomiting are common symptoms in patients with many diseases, including cancer and its treatments. Although the neurological basis of vomiting is reasonably well known, an understanding of the physiology of nausea is lacking. The primary barrier to mechanistic research on the nausea system is the lack of an animal model. Indeed investigating the effects of anti-nausea drugs in preclinical models is difficult because the primary readout is often emesis. It is known that animals show a behavioral profile of sickness, associated with reduced feeding and movement, and possibly these general measures are signs of nausea. Studies attempting to relate the occurrence of additional behaviors to emesis have produced mixed results. Here we applied a statistical method, t-pattern (temporal pattern analysis, to determine patterns of behavior associated with emesis. Musk shrews were injected with the chemotherapy agent cisplatin (a gold standard in emesis research to induce acute (< 24 h and delayed (> 24 h emesis. Emesis and other behaviors were coded and tracked from video files. T-pattern analysis revealed hundreds of non-random patterns of behavior associated with emesis, including sniffing, changes in body contraction, and locomotion. There was little evidence that locomotion was inhibited by the occurrence of emesis. Eating and drinking, and other larger body movements including rearing, grooming, and body rotation, were significantly less common in emesis-related behavioral patterns in real versus randomized data. These results lend preliminary evidence for the expression of emesis-related behavioral patterns, including reduced ingestive behavior, grooming and exploratory behaviors. In summary, this statistical approach to behavioral analysis in a pre-clinical emesis research model could be used to assess the more global effects and limitations of drugs used to control nausea and its potential correlates, including reduced feeding and

  2. Gas-liquid equilibrium in mixtures of methane + m-xylene, and methane + m-cresol

    Energy Technology Data Exchange (ETDEWEB)

    Simnick, J J; Sebastian, H M; Lin, H M; Chao, K C

    1979-01-01

    Compositions of saturated equilibrium liquid and vapor phases as determined in a flow apparatus for methane + m-xylene mixtures at 370/sup 0/, 450/sup 0/, 520/sup 0/, and 600/sup 0/F (190/sup 0/, 230/sup 0/, 270/sup 0/, and 310/sup 0/C) and up to 200 atm, and for methane + m-cresol at 370/sup 0/, 520/sup 0/, 660/sup 0/, and 730/sup 0/F (190/sup 0/, 270/sup 0/, 350/sup 0/, and 390/sup 0/C) and up to 250 atm. Compared with published data on its solubility in benzene, methane appears to be more soluble in m-xylene at similar conditions but substantially less soluble in m-cresol. This difference indicates that the functional groups CH/sub 3/ and OH play different roles in determining the solubility of methane.

  3. The vapor pressure and enthalpy of vaporization of M-xylene

    Energy Technology Data Exchange (ETDEWEB)

    Rothenberg, S J; Seiler, F A; Bechtold, W E; Eidson, A F

    1988-12-01

    We measured the vapor pressure of m-xylene over the temperature range 273 to 293 deg K with a single-sided capacitance manometer. The enthalpy of vaporization was 42.2 {+-} 0.1 (SE) kj/ g{center_dot}mol. Combining our own data with previously published data, we recommend using the values 42.0, 40.6, and 39.1 ({+-} 0.1) (SE) kjg{center_dot}mol for the enthalpy of vaporization of m-xylene at 300, 340, and 380 deg. K, respectively, and a value for the change in heat capacity on vaporization ({delta}Cpdeg.) of 35 {+-} 3 (SE) J/g{center_dot}mol{center_dot}K over the temperature range studied. (author)

  4. The vapor pressure and enthalpy of vaporization of M-xylene

    International Nuclear Information System (INIS)

    Rothenberg, S.J.; Seiler, F.A.; Bechtold, W.E.; Eidson, A.F.

    1988-01-01

    We measured the vapor pressure of m-xylene over the temperature range 273 to 293 deg K with a single-sided capacitance manometer. The enthalpy of vaporization was 42.2 ± 0.1 (SE) kj/ g·mol. Combining our own data with previously published data, we recommend using the values 42.0, 40.6, and 39.1 (± 0.1) (SE) kjg·mol for the enthalpy of vaporization of m-xylene at 300, 340, and 380 deg. K, respectively, and a value for the change in heat capacity on vaporization (ΔCpdeg.) of 35 ± 3 (SE) J/g·mol·K over the temperature range studied. (author)

  5. A study of the electrochemical hydrogenation of o-xylene in a PEM hydrogenation reactor

    International Nuclear Information System (INIS)

    Fonocho, R.; Gardner, C.L.; Ternan, M.

    2012-01-01

    In this study, we investigate the electrochemical hydrogenation of o-xylene in a proton exchange membrane hydrogenation reactor (PEMHR). The reactor was operated isothermally over the temperature range 20–68 °C and at a pressure of 1 atm in a semi-batch mode. Hydrogen was fed into the anode compartment and o-xylene into the cathode. The hydrogenation efficiency was investigated at different current densities and temperatures. Results obtained show that the hydrogenation efficiency increases with temperature but decreases with current density. At low current densities the hydrogenation efficiency approaches 100%. A zero dimensional model was used to fit the data and extract a rate constant for the hydrogenation reaction. The activation energy for this reaction was found to be 28 kJ/mole.

  6. Substoichiometric extraction of rubidium with Dibenzo-24-crown-8 into Xylene

    International Nuclear Information System (INIS)

    Bag, M.; Chattopadhyay, P.; Basu, S.

    2014-01-01

    Owing to immense applications of rubidium in varied fields, extraction and quantification of rubidium have gained great importance in recent years. Here, studies on substoichiometric extraction of rubidium by dibenzo-24-crown-8 into xylene using 86 Rb radiotracer are reported. The method has been optimized by pH of the medium, effects of diverse ions, etc, to explore its applicability in real samples

  7. Development of benzene, toluene, ethylbenzene and xylenes certified gaseous reference materials

    Science.gov (United States)

    Brum, M. C.; Sobrinho, D. C. G.; Fagundes, F. A.; Oudwater, R. J.; Augusto, C. R.

    2016-07-01

    The work describes the production of certified gaseous reference materials of benzene, toluene, ethylbenzene and xylenes (BTEX) in nitrogen from the gravimetric production up to the long term stability tests followed by the certifying step. The uncertainty in the amount fractions of the compounds in these mixtures was approximately 4% (relative) for the range studied from 2 to 16 µmol/mol. Also the adsorption of the BTEX on the cylinder surface and the tubing were investigated as potential uncertainty source.

  8. Heat integration of fractionating systems in para-xylene plants based on column optimization

    International Nuclear Information System (INIS)

    Chen, Ting; Zhang, Bingjian; Chen, Qinglin

    2014-01-01

    In this paper, the optimization of xylene fractionation and disproportionation units in a para-xylene plant is performed through a new method for systematic design based on GCC (grand composite curve) and CGCC (column grand composite curve). The distillation columns are retrofitted by CGCC firstly. Heat Integration between the columns and the background xylene separation process are then explored by GCC. We found that potential retrofits for columns suggested by CGCC provide better possibilities for further Heat Integration. The effectiveness of the retrofits is finally evaluated by means of thermodynamics and economic analysis. The results show that energy consumption of the retrofitted fractionating columns decreases by 7.13 MW. With the improved thermodynamic efficiencies, all columns operate with less energy requirements. Coupled with Heat Integration, the energy input of the para-xylene plant is reduced by 30.90 MW, and the energy outputs are increased by 17 MW and 58 MW for generation of the 3.5 MPa and 2.5 MPa steams. The energy requirement after the Heat Integration is reduced by 12% compared to the original unit. The retrofits required a fixed capital cost of 6268.91 × 10 3  $ and saved about 24790.74 × 10 3  $/year worth of steam. The payback time is approximately 0.26 year for the retrofits. - Highlights: • A new method for systematic design is proposed to improve energy saving of the PX plant in retrofit scenarios. • An optimization approach is developed to identify maximum heat recovery in distillation columns. • An efficient Heat Integration procedure of the PX plant is addressed based on the optimal retrofitted distillation columns. • The energy consumption is reduced by 12% after improvement to an industrial case

  9. Ground rubber: Sorption media for ground water containing benzene and O-xylene

    International Nuclear Information System (INIS)

    Kershaw, D.S.; Pamukcu, S.

    1997-01-01

    The purpose of the current study is to examine the ability of ground rubber to sorb benzene and O-xylene from water contained with aromatic hydrocarbons. The study consisted of running both batch and packed bed column tests to determine the sorption capacity, the required sorption equilibration time, and the flow through utilization efficiency of ground rubber under various contact times when exposed to water contaminated with various amounts of benzene or O-xylene. Initial batch test results indicate that ground rubber can attain equilibrium sorption capacities up to 1.3 or 8.2 mg of benzene or O-xylene, respectively, per gram of tire rubber at solution equilibrium concentrations of 10 mg/L. Packed bed column tests indicate that ground tire rubber has on the average a 40% utilization rate when a hydraulic residence time of 15 min is used. Possible future uses of round rubber as a sorption media could include, but are not limited to, the use of ground rubber as an aggregate in slurry cutoff walls that are in contact with petroleum products. Ground rubber could also be used as a sorption media in pump-and-treat methodologies or as a sorption media in in-situ reactive permeable barriers

  10. Determination of Benzene, Toluene, and Xylene by means of an ion mobility spectrometer device using photoionization

    Science.gov (United States)

    Leonhardt, J. W.; Bensch, H.; Berger, D.; Nolting, M.; Baumbach, J. I.

    1995-01-01

    The continuous monitoring of changes on the quality of ambient air is a field of advantage of ion mobility spectrometry. Benzene, Toluene, and Xylene are substances of special interest because of their toxicity. We present an optimized drift tube for ion mobility spectrometers, which uses photo-ionization tubes to produce the ions to be analyzed. The actual version of this drift tube has a length of 45 mm, an electric field strength established within the drift tube of about 180 V/cm and a shutter-opening-time of 400 mus. With the hydrogen tube used for ionisation a mean flux of 10(exp 12) photons/sq cm s was established for the experiments described. We discuss the results of investigations on Benzene, Toluene, and Xylene in normal used gasoline SUPER. The detection limits obtained with the ion mobility spectrometer developed in co-operation are in the range of 10 ppbv in this case. Normally, charge transfer from Benzene ions to Toluene takes place. Nevertheless the simultaneous determination in mixtures is possible by a data evaluation procedure developed for this case. The interferences found between Xylene and others are rather weak. The ion mobility spectra of different concentrations of gasoline SUPER are attached as an example for the resolution and the detection limit of the instrument developed. Resolution and sensitivity of the system are well demonstrated. A hand-held portable device produced just now is to be tested for special environmental analytical problems in some industrial and scientific laboratories in Germany.

  11. Removal ratio of gaseous toluene and xylene transported from air to root zone via the stem by indoor plants.

    Science.gov (United States)

    Kim, K J; Kim, H J; Khalekuzzaman, M; Yoo, E H; Jung, H H; Jang, H S

    2016-04-01

    This work was designed to investigate the removal efficiency as well as the ratios of toluene and xylene transported from air to root zone via the stem and by direct diffusion from the air into the medium. Indoor plants (Schefflera actinophylla and Ficus benghalensis) were placed in a sealed test chamber. Shoot or root zone were sealed with a Teflon bag, and gaseous toluene and xylene were exposed. Removal efficiency of toluene and total xylene (m, p, o) was 13.3 and 7.0 μg·m(-3)·m(-2) leaf area over a 24-h period in S. actinophylla, and was 13.0 and 7.3 μg·m(-3)·m(-2) leaf area in F. benghalensis. Gaseous toluene and xylene in a chamber were absorbed through leaf and transported via the stem, and finally reached to root zone, and also transported by direct diffusion from the air into the medium. Toluene and xylene transported via the stem was decreased with time after exposure. Xylene transported via the stem was higher than that by direct diffusion from the air into the medium over a 24-h period. The ratios of toluene transported via the stem versus direct diffusion from the air into the medium were 46.3 and 53.7% in S. actinophylla, and 46.9 and 53.1% in F. benghalensis, for an average of 47 and 53% for both species. The ratios of m,p-xylene transported over 3 to 9 h via the stem versus direct diffusion from the air into the medium was 58.5 and 41.5% in S. actinophylla, and 60.7 and 39.3% in F. benghalensis, for an average of 60 and 40% for both species, whereas the ratios of o-xylene transported via the stem versus direct diffusion from the air into the medium were 61 and 39%. Both S. actinophylla and F. benghalensis removed toluene and xylene from the air. The ratios of toluene and xylene transported from air to root zone via the stem were 47 and 60 %, respectively. This result suggests that root zone is a significant contributor to gaseous toluene and xylene removal, and transported via the stem plays an important role in this process.

  12. Effects of Ethnic Settlements and Land Management Status on Species Distribution Patterns: A Case Study of Endangered Musk Deer (Moschus spp.) in Northwest Yunnan, China.

    Science.gov (United States)

    Li, Xueyou; Bleisch, William V; Jiang, Xuelong

    2016-01-01

    Understanding the status and spatial distribution of endangered species in biologically and ethnologically diverse areas is important to address correlates of cultural and biological diversity. We developed models for endangered musk deer (Moschus spp.) abundance indices in and around protected areas inhabited by different ethnic groups in northwest Yunnan China to address different anthropogenic and management-related questions. We found that prediction of relative abundance of musk deer was best accomplished using ethnicity of settlements, conservation status and poaching pressure in an area. Musk deer were around 5 times more abundant in Tibetan regions relative to Lisu regions. We found no significant negative correlates of gathering and transhumance activities on musk deer abundance. Hunting pressure showed no significant differences between protected and non-protected areas, but showed significant differences among ethnic groups. Hunting pressures in areas adjacent to Lisu settlements was 7.1 times more than in areas adjacent to Tibetan settlements. Our findings indicate protected areas in southwest China are not fully effective in deterring human disturbance caused by traditional practices. We suggest that conservation and management strategies should engage traditional culture and practices with a positive conservation impact. Better understanding of indigenous culture may open up new opportunities for species conservation in much wider tracts of unprotected and human-dominated lands. Traditional practices that are not destructive to biodiversity should be allowed as a way of providing a link between the local communities and protected areas thereby creating incentives for conservation.

  13. Multi-objective optimization of p-xylene oxidation process using an improved self-adaptive differential evolution algorithm

    Institute of Scientific and Technical Information of China (English)

    Lili Tao; Bin Xu; Zhihua Hu; Weimin Zhong

    2017-01-01

    The rise in the use of global polyester fiber contributed to strong demand of the Terephthalic acid (TPA). The liquid-phase catalytic oxidation of p-xylene (PX) to TPA is regarded as a critical and efficient chemical process in industry [1]. PX oxidation reaction involves many complex side reactions, among which acetic acid combustion and PX combustion are the most important. As the target product of this oxidation process, the quality and yield of TPA are of great concern. However, the improvement of the qualified product yield can bring about the high energy consumption, which means that the economic objectives of this process cannot be achieved simulta-neously because the two objectives are in conflict with each other. In this paper, an improved self-adaptive multi-objective differential evolution algorithm was proposed to handle the multi-objective optimization prob-lems. The immune concept is introduced to the self-adaptive multi-objective differential evolution algorithm (SADE) to strengthen the local search ability and optimization accuracy. The proposed algorithm is successfully tested on several benchmark test problems, and the performance measures such as convergence and divergence metrics are calculated. Subsequently, the multi-objective optimization of an industrial PX oxidation process is carried out using the proposed immune self-adaptive multi-objective differential evolution algorithm (ISADE). Optimization results indicate that application of ISADE can greatly improve the yield of TPA with low combustion loss without degenerating TA quality.

  14. Rapid intrinsic biodegradation of benzene, toluene, and xylenes at the boundary of a gasoline-contaminated plume under natural attenuation

    Energy Technology Data Exchange (ETDEWEB)

    Takahata, Yoh; Hoaki, Toshihiro [Taisei Corp., Yokohama (Japan). Civil Engineering Research Inst.; Kasai, Yuki; Watanabe, Kazuya [Marine Biotechnology Institute, Kamaishi (Japan)

    2006-12-15

    A groundwater plume contaminated with gasoline constituents [mainly benzene, toluene, and xylenes (BTX)] had been treated by pumping and aeration for approximately 10 years, and the treatment strategy was recently changed to monitored natural attenuation (MNA). To gain information on the feasibility of using MNA to control the spread of BTX, chemical and microbiological parameters in groundwater samples obtained inside and outside the contaminated plume were measured over the course of 73 weeks. The depletion of electron acceptors (i.e., dissolved oxygen, nitrate, and sulfate) and increase of soluble iron were observed in the contaminated zone. Laboratory incubation tests revealed that groundwater obtained immediately outside the contaminated zone (the boundary zone) exhibited much higher potential for BTX degradation than those in the contaminated zone and in uncontaminated background zones. The boundary zone was a former contaminated area where BTX were no longer detected. Denaturing gradient gel electrophoresis (DGGE) analysis of polymerase chain reaction (PCR)-amplified bacterial 16S rRNA gene fragments revealed that DGGE profiles for groundwater samples obtained from the contaminated zone were clustered together and distinct from those from uncontaminated zones. In addition, unique bacterial rRNA types were observed in the boundary zone. These results indicate that the boundary zone in the contaminant plumes served as a natural barrier for preventing the BTX contamination from spreading out. (orig.)

  15. Experimental study and kinetic modeling of the thermal degradation of aromatic volatile organic compounds (benzene, toluene and xylene-para) in methane flames; Etude experimentale et modelisation cinetique de la degradation thermique des composes organiques volatils aromatiques benzenes, toluene et para-xylene dans des flammes de methane

    Energy Technology Data Exchange (ETDEWEB)

    Dupont, L.

    2001-02-01

    This study treats of the thermal degradation of a family of aromatic volatile organic compounds (VOCs) in laminar premixed methane flames at low pressure. The experimental influence of benzene, toluene and xylene-para on the structure of a reference methane flame has been studied. The molar fraction profiles of the stable and reactive, aliphatic, aromatic and cyclic species have been established by the coupling of the molecular beam sampling/mass spectroscopy technique with the gas chromatography/mass spectroscopy technique. Temperature profiles have been measured using a covered thermocouple. A detailed kinetic mechanism of oxidation of these compounds in flame conditions has been developed. Different available sub-mechanisms have been used as references: the GDF-Kin 1.0 model for the oxidation of methane and the models of Tan and Franck (1996) and of Lindstedt and Maurice (1996) in the case of benzene and toluene. In the case of para-xylene, a model has been developed because no mechanisms was available in the literature. These different mechanisms have been refined, completed or adjusted by comparing the experimental results with those obtained by kinetic modeling. The complete kinetic mechanism, comprising 156 chemical species involved in 1072 reactions allows to reproduce all the experimental observations in a satisfactory manner. The kinetic analysis of reactions velocity has permitted to determine oxidation kinetic schemes for benzene, toluene, xylene-para and for the cyclopentadienyl radical, main species at the origin of the rupture of the aromatic cycle. Reactions of recombination with the methyl radicals formed during methane oxidation, of the different aromatic or aliphatic radicals created during the oxidation of aromatics, play an important role and lead to the formation of several aromatic pollutants (ethyl-benzene for instance) or aliphatic pollutants (butadiene or penta-diene for instance) in flames. (J.S.)

  16. Deuterated-xylene (xylene-d{sub 10}; EJ301D): A new, improved deuterated liquid scintillator for neutron energy measurements without time-of-flight

    Energy Technology Data Exchange (ETDEWEB)

    Becchetti, F.D.; Raymond, R.S.; Torres-Isea, R.O. [Department of Physics, University of Michigan, Ann Arbor, MI 48109 (United States); Di Fulvio, A.; Clarke, S.D.; Pozzi, S.A. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Febbraro, M. [Oak Ridge National Laboratory, Oak Ridge, TN 37830 (United States)

    2016-06-01

    In conjunction with Eljen Technology, Inc. (Sweetwater,TX) we have designed, constructed, and evaluated a 3 in. ×3 in. deuterated-xylene organic liquid scintillator (C{sub 8}D{sub 10}; EJ301D) as a fast neutron detector. Similar to deuterated benzene (C{sub 6}D{sub 6}; NE230, BC537, and EJ315) this scintillator can provide good pulse-shape discrimination between neutrons and gamma rays, has good timing characteristics, and can provide a light spectrum with peaks corresponding to discrete neutron energy groups up to ca. 20 MeV. Unlike benzene-based detectors, deuterated xylene is less volatile, less toxic, is not known to be carcinogenic, has a higher flashpoint, and hence is much safer for many applications. In addition EJ301D can provide slightly more light output and better PSD than deuterated-benzene scintillators. We show that, as with deuterated-benzene scintillators, the light-response spectra can be unfolded to provide useable neutron energy spectra without need for time-of-flight (ToF). An array of these detectors arranged at many angles close to a reaction target can be much more effective (×10 to ×100 or more) than an array of long-path ToF detectors which must utilize a narrowly-bunched and pulse-selected beam. As we demonstrate using a small Van de Graaff accelerator, measurements can thus be performed when a bunched and pulse-selected beam (as needed for time-of-flight) is not available.

  17. Quantitative Structure-Relative Volatility Relationship Model for Extractive Distillation of Ethylbenzene/p-Xylene Mixtures: Application to Binary and Ternary Mixtures as Extractive Agents

    International Nuclear Information System (INIS)

    Kang, Young-Mook; Oh, Kyunghwan; You, Hwan; No, Kyoung Tai; Jeon, Yukwon; Shul, Yong-Gun; Hwang, Sung Bo; Shin, Hyun Kil; Kim, Min Sung; Kim, Namseok; Son, Hyoungjun; Chu, Young Hwan; Cho, Kwang-Hwi

    2016-01-01

    Ethylbenzene (EB) and p-xylene (PX) are important chemicals for the production of industrial materials; accordingly, their efficient separation is desired, even though the difference in their boiling points is very small. This paper describes the efforts toward the identification of high-performance extractive agents for EB and PX separation by distillation. Most high-performance extractive agents contain halogen atoms, which present health hazards and are corrosive to distillation plates. To avoid this disadvantage of extractive agents, we developed a quantitative structure-relative volatility relationship (QSRVR) model for designing safe extractive agents. We have previously developed and reported QSRVR models for single extractive agents. In this study, we introduce extended QSRVR models for binary and ternary extractive agents. The QSRVR models accurately predict the relative volatilities of binary and ternary extractive agents. The service to predict the relative volatility for binary and ternary extractive agents is freely available from the Internet at http://qsrvr.o pengsi.org/.

  18. Quantitative Structure-Relative Volatility Relationship Model for Extractive Distillation of Ethylbenzene/p-Xylene Mixtures: Application to Binary and Ternary Mixtures as Extractive Agents

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Young-Mook; Oh, Kyunghwan; You, Hwan; No, Kyoung Tai [Bioinformatics and Molecular Design Research Center, Seoul (Korea, Republic of); Jeon, Yukwon; Shul, Yong-Gun; Hwang, Sung Bo; Shin, Hyun Kil; Kim, Min Sung; Kim, Namseok; Son, Hyoungjun [Yonsei University, Seoul (Korea, Republic of); Chu, Young Hwan [Sangji University, Wonju (Korea, Republic of); Cho, Kwang-Hwi [Soongsil University, Seoul (Korea, Republic of)

    2016-04-15

    Ethylbenzene (EB) and p-xylene (PX) are important chemicals for the production of industrial materials; accordingly, their efficient separation is desired, even though the difference in their boiling points is very small. This paper describes the efforts toward the identification of high-performance extractive agents for EB and PX separation by distillation. Most high-performance extractive agents contain halogen atoms, which present health hazards and are corrosive to distillation plates. To avoid this disadvantage of extractive agents, we developed a quantitative structure-relative volatility relationship (QSRVR) model for designing safe extractive agents. We have previously developed and reported QSRVR models for single extractive agents. In this study, we introduce extended QSRVR models for binary and ternary extractive agents. The QSRVR models accurately predict the relative volatilities of binary and ternary extractive agents. The service to predict the relative volatility for binary and ternary extractive agents is freely available from the Internet at http://qsrvr.o pengsi.org/.

  19. CHEMICALS

    CERN Multimedia

    Medical Service

    2002-01-01

    It is reminded that all persons who use chemicals must inform CERN's Chemistry Service (TIS-GS-GC) and the CERN Medical Service (TIS-ME). Information concerning their toxicity or other hazards as well as the necessary individual and collective protection measures will be provided by these two services. Users must be in possession of a material safety data sheet (MSDS) for each chemical used. These can be obtained by one of several means : the manufacturer of the chemical (legally obliged to supply an MSDS for each chemical delivered) ; CERN's Chemistry Service of the General Safety Group of TIS ; for chemicals and gases available in the CERN Stores the MSDS has been made available via EDH either in pdf format or else via a link to the supplier's web site. Training courses in chemical safety are available for registration via HR-TD. CERN Medical Service : TIS-ME :73186 or service.medical@cern.ch Chemistry Service : TIS-GS-GC : 78546

  20. Determination of radon in indoor air in Quebec by liquid scintillation counting in ortho-xylene

    Energy Technology Data Exchange (ETDEWEB)

    Chah, B; Zikovsky, L; Champagne, P [Ecole Polytechnique, Montreal, PQ (Canada)

    1992-01-01

    A new method for the determination of radon in air has been developed. it is based on low temperature absorption of radon in ortho-xylene followed by liquid scintillation counting. The method is reasonably fast and sensitive enough to analyse air without precipitation. The detection limit at the 95% confidence level for a 20 l air sample and 1 h counting time is 2 mBql{sup -1}. Radon concentrations measured in indoor air in Quebec varied from 7 to 162 mBql{sup -1}. (Author).

  1. Incidence of dental lesions in musk shrews (Suncus murinus) and their association with sex, age, body weight and diet.

    Science.gov (United States)

    Dudley, Emily S; Grunden, Beverly K; Crocker, Conan; Boivin, Gregory P

    2013-10-22

    Both wild and laboratory strains of the musk shrew (Suncus murinus) have a high incidence of periodontitis. The authors completed necropsy examinations in 51 shrews to identify dental lesions including tooth loss, mobility and fractures. Dental lesions were identified in significantly more females than males, and older animals were more likely to have lesions present. Shrews with one or more dental lesions weighed significantly less than those without lesions present. Dietary supplementation with mealworms did not significantly affect the incidence of dental lesions or the body weight of male or female shrews. The authors recommend routine body weight measurement as a simple, noninvasive method of detecting shrews with an increased likelihood of having dental lesions.

  2. Thermophysical properties for (diethyl carbonate + p-xylene + octane) ternary system

    Energy Technology Data Exchange (ETDEWEB)

    Mosteiro, L. [Departamento de Fisica Aplicada, Facultad de Ciencias Experimentales, Universidad de Vigo, Lagoas Marcosende s/n, 36310 Vigo (Spain); Casas, L.M., E-mail: lmcasas@uvigo.es [Departamento de Fisica Aplicada, Facultad de Ciencias Experimentales, Universidad de Vigo, Lagoas Marcosende s/n, 36310 Vigo (Spain); Curras, M.R. [Departamento de Fisica Aplicada, Facultad de Ciencias Experimentales, Universidad de Vigo, Lagoas Marcosende s/n, 36310 Vigo (Spain); Mariano, A.B. [Laboratorio de Fisicoquimica, Departamento de Quimica, Facultad de Ingenieria, Universidad Nacional de Comahue, 8300 Neuquen (Argentina); Legido, J.L. [Departamento de Fisica Aplicada, Facultad de Ciencias Experimentales, Universidad de Vigo, Lagoas Marcosende s/n, 36310 Vigo (Spain)

    2011-12-15

    Highlights: > Thermophysical properties of (diethyl carbonate + p-xylene + octane) were measured. > Excess molar volumes and isentropic compressibilities were determined and correlated. > Ternary surface tension deviations were correlated using Cibulka equation. > Intermolecular interactions based on the derived properties trend were discussed. - Abstract: The density and speed of sound of the ternary mixture (diethyl carbonate + p-xylene + octane) have been measured at atmospheric pressure and in the temperature range T = (288.15 to 308.15) K. Besides, surface tension has been also determined for the same mixture at T = 298.15 K. The experimental measurements have allowed the calculation of the corresponding derived properties: excess molar volumes, excess isentropic compressibilities, and surface tension deviations. Excess properties have been correlated using Nagata and Tamura equation and correlation for the surface tension deviation has been done with the Cibulka equation. Good accuracy has been obtained. Based on the variations of the derived properties values with composition, a qualitative discussion about the intermolecular interactions was drawn.

  3. Biocomplementation of SVE to achieve clean-up goals in soils contaminated with toluene and xylene.

    Science.gov (United States)

    Soares, António Alves; Pinho, Maria Teresa; Albergaria, José Tomás; Domingues, Valentina; da Conceição Alvim-Ferraz, Maria; Delerue-Matos, Cristina

    2013-10-01

    Soil vapor extraction (SVE) and bioremediation (BR) are two of the most common soil remediation technologies. Their application is widespread; however, both present limitations, namely related to the efficiencies of SVE on organic soils and to the remediation times of some BR processes. This work aimed to study the combination of these two technologies in order to verify the achievement of the legal clean-up goals in soil remediation projects involving seven different simulated soils separately contaminated with toluene and xylene. The remediations consisted of the application of SVE followed by biostimulation. The results show that the combination of these two technologies is effective and manages to achieve the clean-up goals imposed by the Spanish Legislation. Under the experimental conditions used in this work, SVE is sufficient for the remediation of soils, contaminated separately with toluene and xylene, with organic matter contents (OMC) below 4 %. In soils with higher OMC, the use of BR, as a complementary technology, and when the concentration of contaminant in the gas phase of the soil reaches values near 1 mg/L, allows the achievement of the clean-up goals. The OMC was a key parameter because it hindered SVE due to adsorption phenomena but enhanced the BR process because it acted as a microorganism and nutrient source.

  4. Wetlands for the remediation of BTEX [benzene, toluene, ethylbenzene, xylenes] contamination: Amalgamation of policy and technology

    International Nuclear Information System (INIS)

    Main, C.J.

    1993-01-01

    The fate and transport of benzene, toluene, ethylbenzene, and xylenes (BTEX) as they pass from a groundwater to a surface water environment was studied in three separate field experiments. The first examined the fate of BTEX from a spilled gasoline plume as it travelled vertically in the groundwater flow regime from a mineral soil unit through an organic soil unit to a surface wetland. The second considered surface water processes in the swamp that result in losses of BTEX concentrations. The final experiment evaluated the effects of seasonal and temporal changes on the processes occurring in the swamp that affect the fate and transport of BTEX under natural flow conditions. Significant reductions in BTEX were observed as the plume travelled vertically to reach the surface water. Reductions in contaminant levels were primarily due to sorption and biodegradation. On reaching the surface, overall reduction of compound concentration over 6 m of horizontal flow ranged from 92% for benzene to 85% for m-xylene. BTEX losses were mainly due to dilution, volatilization, and sorption. Limitations existing in the approach taken by present legislation and guidelines for wetland protection are discussed. Reactive legislation and guidelines should allow natural remediation of contamination in wetlands to be considered, especially when contaminant remediation requires alteration of the hydrologic flow regime or removal of contaminated material that may result in elimination of the wetland. 70 refs., 20 figs., 14 tabs

  5. Densities and volumetric properties of binary mixtures of xylene with N,N-dimethylformamide at different temperatures

    International Nuclear Information System (INIS)

    Chen Bin; Liu Wei

    2007-01-01

    Densities of binary mixtures of o-xylene, or m-xylene, or p-xylene with N,N-dimethylformamide have been measured over the full range of compositions at atmospheric pressure and various temperatures by means of a vibrating-tube densimeter. The excess molar volume V m E , calculated from the density data, provides the temperature dependence of V m E in the temperature range (293.15 to 353.15)K. The V m E results were correlated using the fourth-order Redlich-Kister polynomial equation, with the maximum likelihood principle being applied for the determination of the adjustable parameters. Partial molar volumes and excess partial molar volumes of two components were also calculated. It was found that the V m E in the systems studied increase with rising temperature

  6. Densities and volumetric properties of a (xylene + dimethyl sulfoxide) at temperature from (293.15 to 353.15) K

    International Nuclear Information System (INIS)

    Wang Haijun; Liu Wei; Huang Jihou

    2004-01-01

    The densities of (o-xylene, or m-xylene, or p-xylene + dimethyl sulfoxide) were measured at temperatures (293.15, 303.15, 313.15, 323.15, 333.15, 343.15, 353.15) K and atmospheric pressure by means of a vibrating-tube densimeter. The excess molar volume V m E calculated from the density data provide the temperature dependence of V m E in the temperature range of (293.15 to 353.15) K. The V m E results were correlated using the fourth-order Redlich-Kister equation, with the maximum likelihood principle being applied for the determination of the adjustable parameters. Also we have calculated partial molar volume and excess partial molar volumes of two components. It was found that the V m E in the systems studied increase with rising temperature

  7. Evaluation of biosafe alternatives as xylene substitutes in hematoxylin and eosin staining procedure: A comparative pilot study

    Science.gov (United States)

    Sravya, Taneeru; Rao, Guttikonda Venkateswara; Kumari, Masabattula Geetha; Sagar, Yerraguntla Vidya; Sivaranjani, Yeluri; Sudheerkanth, Kondamarri

    2018-01-01

    Background: Xylene is synthetic hydrocarbon produced from coal tar known for its wide usage as universal solvent which has many hazardous effects. The aim of this study is to compare the efficacy of xylene-free hematoxylin and eosin (H and E) sections with conventional H and E sections. Materials and Methods: The study included ninety paraffin-embedded tissue blocks. Of these, sixty blocks were processed with sesame oil (xylene alternative) and thirty blocks with xylene. The study sample was divided into three groups. Sixty sections which are taken from sesame oil-processed blocks were stained with xylene-free H and E staining method. In xylene-free staining method, 95% diluted lemon water (Group A) and 1.7% dish washing solution (DWS, Group B) were used as deparaffinizing agents whereas the remaining 30 sections were processed with xylene and stained with conventional H and E staining method (Group C). Slides were scored for the following parameters: (i) nuclear staining (adequate = score 1, inadequate = score 0), (ii) cytoplasmic staining (adequate = score 1, inadequate = score 0), (iii) uniformity (present = score 1, absent = score 0), (iv) clarity (present = score 1, absent = score 0) and (v) intensity (present = score 1, absent = score 0). Score ≤2 was considered inadequate for diagnosis while scores 3–5 were considered adequate for diagnosis. Results: Adequate nuclear staining was noted in 90% of sections of Group A and 100% each in Group B and Group C (P 0.05); adequate uniformity of staining in 53.3% of sections of Group A, 70% in Group B and 83.3% in Group C (P 0.05) and adequate intensity of staining in 76.7% sections of Group A, 93.3% in Group B and 100% in Group C (P < 0.05). Group C sections stained adequate for diagnosis (93.3%) followed by Group B (88.7%) and Group A (78%; P < 0.05). Conclusion: Tissues processed with sesame oil and stained using 1.7% DWS were found to be effective alternative to xylene.

  8. Determination of Muscone in Rats Plasma following Oral Administration of Artificial Musk: Using of Combined Headspace Gas Chromatography-Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Qibiao Wu

    2014-01-01

    Full Text Available To develop an analytical method for determination of plasma concentrations of muscone in rats following oral administration of artificial musk, with the aim of investigating the pharmacokinetic profile of artificial musk. Plasma samples were pretreated with acetonitrile to precipitate proteins. Headspace injection coupled with gas chromatography-mass spectrometry was used for quantitative analysis of muscone concentrations. A strong linear relationship was obtained for plasma muscone concentrations ranging from 75.6 to 7560 ng·mL−1  R2=0.9998, with the minimum detectable concentration being 25 ng·mL−1. The within-day and interday precision for determination of three different concentrations of muscone were favorable (RSD < 25%. The average absolute recovery ranged from 83.7 to 88.6%, with an average relative recovery of 100.5 to 109.8%. The method described was characterized by stability and reliability, and in the present study showed significant specificity and high sensitivity. This method would be applicable to the analysis of plasma concentrations of muscone in preclinical contexts, where artificial musk is used.

  9. Selective Production of Renewable para-Xylene by Tungsten Carbide Catalyzed Atom-Economic Cascade Reactions.

    Science.gov (United States)

    Dai, Tao; Li, Changzhi; Li, Lin; Zhao, Zongbao Kent; Zhang, Bo; Cong, Yu; Wang, Aiqin

    2018-02-12

    Tungsten carbide was employed as the catalyst in an atom-economic and renewable synthesis of para-xylene with excellent selectivity and yield from 4-methyl-3-cyclohexene-1-carbonylaldehyde (4-MCHCA). This intermediate is the product of the Diels-Alder reaction between the two readily available bio-based building blocks acrolein and isoprene. Our results suggest that 4-MCHCA undergoes a novel dehydroaromatization-hydrodeoxygenation cascade process by intramolecular hydrogen transfer that does not involve an external hydrogen source, and that the hydrodeoxygenation occurs through the direct dissociation of the C=O bond on the W 2 C surface. Notably, this process is readily applicable to the synthesis of various (multi)methylated arenes from bio-based building blocks, thus potentially providing a petroleum-independent solution to valuable aromatic compounds. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. High activity of iron containing metal-organic-framework in acylation of p-xylene with benzoyl chloride

    Czech Academy of Sciences Publication Activity Database

    Kurfiřtová, Lenka; Seo, Y.; K.; Hwang, Y. K.; Chang, J.; S.; Čejka, Jiří

    2012-01-01

    Roč. 179, č. 1 (2012), s. 85-90 ISSN 0920-5861 R&D Projects: GA ČR GA104/07/0383 Institutional research plan: CEZ:AV0Z40400503 Keywords : acylation * p-xylene * zeolites Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.980, year: 2012

  11. Agrin-LRP4-MuSK signaling as a therapeutic target for myasthenia gravis and other neuromuscular disorders.

    Science.gov (United States)

    Ohno, Kinji; Ohkawara, Bisei; Ito, Mikako

    2017-10-01

    Signal transduction at the neuromuscular junction (NMJ) is compromised in a diverse array of diseases including myasthenia gravis, Lambert-Eaton myasthenic syndrome, Isaacs' syndrome, congenital myasthenic syndromes, Fukuyama-type congenital muscular dystrophy, amyotrophic lateral sclerosis, and sarcopenia. Except for sarcopenia, all are orphan diseases. In addition, the NMJ signal transduction is impaired by tetanus, botulinum, curare, α-bungarotoxin, conotoxins, organophosphate, sarin, VX, and soman to name a few. Areas covered: This review covers the agrin-LRP4-MuSK signaling pathway, which drives clustering of acetylcholine receptors (AChRs) and ensures efficient signal transduction at the NMJ. We also address diseases caused by autoantibodies against the NMJ molecules and by germline mutations in genes encoding the NMJ molecules. Expert opinion: Representative small compounds to treat the defective NMJ signal transduction are cholinesterase inhibitors, which exert their effects by increasing the amount of acetylcholine at the synaptic space. Another possible therapeutic strategy to enhance the NMJ signal transduction is to increase the number of AChRs, but no currently available drug has this functionality.

  12. Recessive variants of MuSK are associated with late onset CMS and predominant limb girdle weakness.

    Science.gov (United States)

    Owen, David; Töpf, Ana; Preethish-Kumar, Veeramani; Lorenzoni, Paulo José; Vroling, Bas; Scola, Rosana Herminia; Dias-Tosta, Elza; Geraldo, Argemiro; Polavarapu, Kiran; Nashi, Saraswati; Cox, Daniel; Evangelista, Teresinha; Dawson, John; Thompson, Rachel; Senderek, Jan; Laurie, Steven; Beltran, Sergi; Gut, Marta; Gut, Ivo; Nalini, Atchayaram; Lochmüller, Hanns

    2018-04-28

    Congenital myasthenic syndrome (CMS) is a heterogeneous disorder that causes fatigable muscle weakness. CMS has been associated with variants in the MuSK gene and, to date, 16 patients have been reported. MuSK-CMS patients present a different phenotypic pattern of limb girdle weakness. Here, we describe four additional patients and discuss the phenotypic and clinical relationship with those previously reported. Two novel damaging missense variants are described: c.1742T > A; p.I581N found in homozygosis, and c.1634T > C; p.L545P found in compound heterozygosis with p.R166*. The reported patients had predominant limb girdle weakness with symptom onset at 12, 17, 18, and 30 years of age, and the majority exhibited a good clinical response to Salbutamol therapy, but not to esterase inhibitors. Meta-analysis including previously reported variants revealed an increased likelihood of a severe, respiratory phenotype with null alleles. Missense variants exclusively affecting the kinase domain, but not the catalytic site, are associated with late onset. These data refine the phenotype associated with MuSK-related CMS. © 2018 Wiley Periodicals, Inc.

  13. The influence of the association patterns of phosphorus–substrates and xylene–substrates on the degradation of xylenes in an alluvial aquifer

    Directory of Open Access Journals (Sweden)

    SANJA MRKIC

    2005-12-01

    Full Text Available The association patterns of xylene and of total phosphorus with sediment constituents in an alluvial aquifer consisting of clays and sands which had been contaminated by a spill of technical grade xylene were investigated with the aim of assessing the dependence of in situ xylene degradation on the P-availability. The investigated alluvial sediments of the Maki{ Plain (Sava river alluvion, Quaternary age, Serbia and Montenegro are relatively poor in P. The most reliable associations were proposed by analyzing the quality of the correlations of xylene- and of P-contents with 32 sediment characteristics. The association patterns depend on the mineralogical and granulometrical composition of sediments, the structural characteristics of the organicmatter (N/C-ratio and the redox-conditions. Differing association patterns in the clays and the sand had been developed, and these characteristics influence the intrinsic xylene degradation. The main proof for the occurrence of xylene degradation is the percentul share of bacteria which oxidize xylene as a single carbon-source.

  14. Biofiltration and inhibitory interactions of gaseous benzene, toluene, xylene, and methyl tert-butyl ether.

    Science.gov (United States)

    Shim, Eun-Hwa; Kim, Jaisoo; Cho, Kyung-Suk; Ryu, Hee Wook

    2006-05-01

    This study evaluated the individual and combined removal capacities of benzene, toluene, and xylene (B, T, and X) in the presence and absence of methyl tert-butyl ether (MTBE) in a polyurethane biofilter inoculated with a BTX-degrading microbial consortium, and further examined their interactive effects in various mixtures. In addition, Polymerase chain reaction-denaturing gradient gel electrophoresis and phylogenetic analysis of 16S rRNA gene sequences were used to compare the microbial community structures found in biofilters exposed to the various gases and gas mixtures. The maximum individual elimination capacities (MECs) of B, T, and X were 200, 238, and 400 g m(-3) h(-1), respectively. There was no significant elimination of MTBE alone. Addition of MTBE decreased the MECs of B,T, and X to 75, 100, and 300 g m(-3) h(-1), respectively, indicating that benzene was most strongly inhibited by MTBE. When the three gases were mixed (B + T + X), the removal capacities of individual B, T, and X were 50, 90, and 200 g m(-3) h(-1), respectively. These capacities decreased to 40, 50, and 100 g m(-3) h(-1) when MTBE was added to the mix. The MEC of the three-gas mixture (B + T + X) was 340 g m(-3) h(-1), and that of the four-gas mixture was 200 g m(-3) h(-1). Although MTBE alone was not degraded by the biofilter, it could be co-metabolically degraded in the presence of toluene, benzene, or xylene with the MECs of 34, 23, and 14 g m(-3) h(-1), respectively. The microbial community structure analysis revealed that two large groups could be distinguished based on the presence or absence of MTBE, and many of the dominant bacteria in the consortia were closely related to bacteria isolated from aromatic hydrocarbon-contaminated sites and/ or oil wastewaters. These findings provide important new insights into biofiltration and may be used to improve the rational design of biofilters for remediation of petroleum gas-contaminated airstreams according to composition types of mixed

  15. 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.)

  16. Analysis of benzene, toluene, ethylbenzene and xylenes in soils by headspace and gas chromatography/flame ionization detector

    Directory of Open Access Journals (Sweden)

    Jurandir Pereira Pinto

    2006-02-01

    Full Text Available The constituents of gasoline: benzene, toluene, ethylbenzene and xylenes (BTEX are frequently found in soils due to leaks in fuel storage tanks and they present chronic toxicity. In this work it was developed and validated a methodology of BTEX analysis in soil by gas chromatography/ flame ionization detector and static headspace. The recovery of BTEX in soil samples was evaluated using soils with different textures (sandy and loamy. The analysis method showed good resolution, in a low time of analysis (less than 30 minutes. Limits of quantification of 0.05 mg Kg¯¹ soil for benzene, toluene, ethylbenzene and xylenes are below the guiding values that range from 0.15 to 95 mg Kg¯¹ soil, established to determine soil quality. It was verified that the methodology enables the use of this method for BTEX analysis of soil samples for passive environmental identification of gas stations.

  17. Selective liquid-liquid extraction of antimony(III from hydrochloric acid media by N-n-octylaniline in xylene

    Directory of Open Access Journals (Sweden)

    M. A. ANUSE

    2004-04-01

    Full Text Available N-n-Octylaniline in xylene was used for the extraction separation of antimony(III from hydrochloric acid media. Antimony(III was extracted quantitatively with 10 mL 4 % N-n-octylaniline in xylene. It was stripped from the organic phase with 0.5 M ammonia and estimated photometrically by the iodide method. The effect of metal ion, acid, reagent concentration and various foreign ions was investigated. The method affords binary and ternary separation of antimony(III from tellurium(IV, selenium(IV, lead(II, bismuth(III, tin(IV, germanium(IV, copper(II, gold(III, iron(III and zinc(II. The method is applicable for the analysis of synthetic mixtures, alloys and semiconductor thin films. It is fast, accurate and precise.

  18. Removal of traces of toluene and p-xylene in indoor air using biofiltration and a hybrid system (biofiltration + adsorption).

    Science.gov (United States)

    Luengas, Angela Tatiana; Hort, Cécile; Platel, Vincent; Elias, Ana; Barona, Astrid; Moynault, Laurent

    2017-04-01

    Biofiltration technology and the hybrid system combining biofiltration and adsorption (onto activated carbon) were compared as possible methods to toluene and p-xylene at parts per million concentration levels (2-45 and 1-33 ppb, respectively). An organic material was used as packing material for the biofiltration process. Even at low empty bed residence times (EBRTs) and concentrations, toluene removal efficiency reached 100% and p-xylene showed an increasing trend on their removal efficiency over the time using biofiltration. The assessment of by-products and particle generation by the biofilter and the hybrid system were taken into account. Acetone and acetic acid were identified as by-products of the biofilter. Particle emissions in the range of 0.03 to 10 μm were recorded for both systems.

  19. Evaluation of potential toxicity from co-exposure to three CNS depressants (toluene, ethylbenzene, and xylene) under resting and working conditions using PBPK modeling.

    Science.gov (United States)

    Dennison, James E; Bigelow, Philip L; Mumtaz, Moiz M; Andersen, Melvin E; Dobrev, Ivan D; Yang, Raymond S H

    2005-03-01

    Under OSHA and American Conference of Governmental Industrial Hygienists (ACGIH) guidelines, the mixture formula (unity calculation) provides a method for evaluating exposures to mixtures of chemicals that cause similar toxicities. According to the formula, if exposures are reduced in proportion to the number of chemicals and their respective exposure limits, the overall exposure is acceptable. This approach assumes that responses are additive, which is not the case when pharmacokinetic interactions occur. To determine the validity of the additivity assumption, we performed unity calculations for a variety of exposures to toluene, ethylbenzene, and/or xylene using the concentration of each chemical in blood in the calculation instead of the inhaled concentration. The blood concentrations were predicted using a validated physiologically based pharmacokinetic (PBPK) model to allow exploration of a variety of exposure scenarios. In addition, the Occupational Safety and Health Administration and ACGIH occupational exposure limits were largely based on studies of humans or animals that were resting during exposure. The PBPK model was also used to determine the increased concentration of chemicals in the blood when employees were exercising or performing manual work. At rest, a modest overexposure occurs due to pharmacokinetic interactions when exposure is equal to levels where a unity calculation is 1.0 based on threshold limit values (TLVs). Under work load, however, internal exposure was 87%higher than provided by the TLVs. When exposures were controlled by a unity calculation based on permissible exposure limits (PELs), internal exposure was 2.9 and 4.6 times the exposures at the TLVs at rest and workload, respectively. If exposure was equal to PELs outright, internal exposure was 12.5 and 16 times the exposure at the TLVs at rest and workload, respectively. These analyses indicate the importance of (1) selecting appropriate exposure limits, (2) performing unity

  20. Advanced oxidation of benzene, toluene, ethylbenzene and xylene isomers (BTEX) by Trametes versicolor.

    Science.gov (United States)

    Aranda, Elisabet; Marco-Urrea, Ernest; Caminal, Gloria; Arias, María E; García-Romera, Inmaculada; Guillén, Francisco

    2010-09-15

    Advanced oxidation of benzene, toluene, ethylbenzene, and o-, m-, and p-xylene (BTEX) by the extracellular hydroxyl radicals (*OH) generated by the white-rot fungus Trametes versicolor is for the first time demonstrated. The production of *OH was induced by incubating the fungus with 2,6-dimethoxy-1,4-benzoquinone (DBQ) and Fe3+-EDTA. Under these conditions, *OH were generated through DBQ redox cycling catalyzed by quinone reductase and laccase. The capability of T. versicolor growing in malt extract medium to produce *OH by this mechanism was shown during primary and secondary metabolism, and was quantitatively modulated by the replacement of EDTA by oxalate and Mn2+ addition to DBQ incubations. Oxidation of BTEX was observed only under *OH induction conditions. *OH involvement was inferred from the high correlation observed between the rates at which they were produced under different DBQ redox cycling conditions and those of benzene removal, and the production of phenol as a typical hydroxylation product of *OH attack on benzene. All the BTEX compounds (500 microM) were oxidized at a similar rate, reaching an average of 71% degradation in 6 h samples. After this time oxidation stopped due to O2 depletion in the closed vials used in the incubations. Copyright 2010 Elsevier B.V. All rights reserved.

  1. Experimental vapor-liquid equilibria data for binary mixtures of xylene isomers

    Directory of Open Access Journals (Sweden)

    W.L. Rodrigues

    2005-09-01

    Full Text Available Separation of aromatic C8 compounds by distillation is a difficult task due to the low relative volatilities of the compounds and to the high degree of purity required of the final commercial products. For rigorous simulation and optimization of this separation, the use of a model capable of describing vapor-liquid equilibria accurately is necessary. Nevertheless, experimental data are not available for all binaries at atmospheric pressure. Vapor-liquid equilibria data for binary mixtures were isobarically obtained with a modified Fischer cell at 100.65 kPa. The vapor and liquid phase compositions were analyzed with a gas chromatograph. The methodology was initially tested for cyclo-hexane+n-heptane data; results obtained are similar to other data in the literature. Data for xylene binary mixtures were then obtained, and after testing, were considered to be thermodynamically consistent. Experimental data were regressed with Aspen Plus® 10.1 and binary interaction parameters were reported for the most frequently used activity coefficient models and for the classic mixing rules of two cubic equations of state.

  2. Post-Synthesis Modification of SSZ-35 Zeolite to Enhance the Selectivity in p-Xylene Alkylation with Isopropyl Alcohol

    Czech Academy of Sciences Publication Activity Database

    Musilová, Zuzana; Zones, S. I.; Čejka, Jiří

    2010-01-01

    Roč. 53, 3-4 (2010), s. 273-282 ISSN 1022-5528 R&D Projects: GA AV ČR 1QS400400560; GA ČR GD203/08/H032 Institutional research plan: CEZ:AV0Z40400503 Keywords : SSZ-35 * surface modification * p-xylene * 2,5-dimethylcumene Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.359, year: 2010

  3. Integration of processes induced air flotation and photo-Fenton for treatment of residual waters contaminated with xylene

    International Nuclear Information System (INIS)

    Silva, Syllos S. da; Chiavone-Filho, Osvaldo; Barros Neto, Eduardo L. de; Nascimento, Claudio A.O.

    2012-01-01

    Highlights: ► We have studied the treatment of wastewater contaminated with hydrocarbons represented by the xylene, using these processes in an integrated mode: induced air flotation and photo-Fenton. ► We have selected xylene as representative contaminant due to properties of toxicity, solubility in water and vapor pressure. ► The manuscript presents a series of accurate experimental data that can be useful for material and energy optimization purposes in the xylene removal aiming the treatment of oil field produced water. - Abstract: Produced water in oil fields is one of the main sources of wastewater generated in the industry. It contains several organic compounds, such as benzene, toluene, ethyl benzene and xylene (BTEX), whose disposal is regulated by law. The aim of this study is to investigate a treatment of produced water integrating two processes, i.e., induced air flotation (IAF) and photo-Fenton. The experiments were conducted in a column flotation and annular lamp reactor for flotation and photodegradation steps, respectively. The first order kinetic constant of IAF for the wastewater studied was determined to be 0.1765 min −1 for the surfactant EO 7. Degradation efficiencies of organic loading were assessed using factorial planning. Statistical data analysis shows that H 2 O 2 concentration is a determining factor in process efficiency. Degradations above 90% were reached in all cases after 90 min of reaction, attaining 100% mineralization in the optimized concentrations of Fenton reagents. Process integration was adequate with 100% organic load removal in 20 min. The results of the integration of the IAF with the photo-Fenton allowed to meet the effluent limits established by Brazilian legislation for disposal.

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

    International Nuclear Information System (INIS)

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

    2004-12-01

    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.)

  5. The Effect of Zeolite Structure on the Activity and Selectivity in p-Xylene Alkylation with Isopropyl Alcohol

    Czech Academy of Sciences Publication Activity Database

    Musilová, Zuzana; Kubů, Martin; Burton, A. W.; Zones, S. I.; Voláková, Martina; Čejka, Jiří

    2009-01-01

    Roč. 131, 3-4 (2009), s. 393-400 ISSN 1011-372X R&D Projects: GA AV ČR 1QS400400560; GA ČR GD203/08/H032 Institutional research plan: CEZ:AV0Z40400503 Keywords : SSZ-35 * SSZ-33 * p-xylene * alkylation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.021, year: 2009

  6. Integration of processes induced air flotation and photo-Fenton for treatment of residual waters contaminated with xylene

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Syllos S. da [Departamento Engenharia Quimica, NUPEG, Universidade Federal do Rio Grande do Norte, Campus Universitario, Lagoa Nova, Natal 59066-800, RN (Brazil); Chiavone-Filho, Osvaldo, E-mail: osvaldo@eq.ufrn.br [Departamento Engenharia Quimica, NUPEG, Universidade Federal do Rio Grande do Norte, Campus Universitario, Lagoa Nova, Natal 59066-800, RN (Brazil); Barros Neto, Eduardo L. de [Departamento Engenharia Quimica, NUPEG, Universidade Federal do Rio Grande do Norte, Campus Universitario, Lagoa Nova, Natal 59066-800, RN (Brazil); Nascimento, Claudio A.O. [Departamento de Engenharia Quimica, Escola Politecnica, Universidade de Sao Paulo, Cidade Universitaria, Sao Paulo 05508-900, SP (Brazil)

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer We have studied the treatment of wastewater contaminated with hydrocarbons represented by the xylene, using these processes in an integrated mode: induced air flotation and photo-Fenton. Black-Right-Pointing-Pointer We have selected xylene as representative contaminant due to properties of toxicity, solubility in water and vapor pressure. Black-Right-Pointing-Pointer The manuscript presents a series of accurate experimental data that can be useful for material and energy optimization purposes in the xylene removal aiming the treatment of oil field produced water. - Abstract: Produced water in oil fields is one of the main sources of wastewater generated in the industry. It contains several organic compounds, such as benzene, toluene, ethyl benzene and xylene (BTEX), whose disposal is regulated by law. The aim of this study is to investigate a treatment of produced water integrating two processes, i.e., induced air flotation (IAF) and photo-Fenton. The experiments were conducted in a column flotation and annular lamp reactor for flotation and photodegradation steps, respectively. The first order kinetic constant of IAF for the wastewater studied was determined to be 0.1765 min{sup -1} for the surfactant EO 7. Degradation efficiencies of organic loading were assessed using factorial planning. Statistical data analysis shows that H{sub 2}O{sub 2} concentration is a determining factor in process efficiency. Degradations above 90% were reached in all cases after 90 min of reaction, attaining 100% mineralization in the optimized concentrations of Fenton reagents. Process integration was adequate with 100% organic load removal in 20 min. The results of the integration of the IAF with the photo-Fenton allowed to meet the effluent limits established by Brazilian legislation for disposal.

  7. Benzene, toluene and p-xylene interactions and the role of microbial communities in remediation using bioventing

    Energy Technology Data Exchange (ETDEWEB)

    Sui, H. [Tianjin Univ., Tianjin (China). School of Chemical Engineering and Technology; Tianjin Univ., Tianjin (China). National Engineering Research Center for Distillation Technology; Li, X.G.; Jiang, B. [Tianjin Univ., Tianjin (China). National Engineering Research Center for Distillation Technology

    2005-04-01

    Bioventing is a promising in-situ soil remediation technology used to clean soils and groundwater contaminated by aromatic hydrocarbon components benzene, toluene and xylene (BTX). These contaminants are present at numerous hazardous waste sites. Bioventing provides enough oxygen to stimulate aerobic biodegradation by indigenous microorganisms. It is not constrained by contaminant volatility and can therefore be applied to contaminants that are readily biodegradable even if they are not highly volatile. This study examined the volatilization and biodegradation of BTX during bioventing from unsaturated soil. It focused on the occurrence of any substrate interaction and the effects of indigenous microbial inocula. The soil was inoculated with indigenous microorganisms obtained from the Dagang Oil Field in Tianjin, China. Then, different amounts of BTX were added to the soil in a stainless steel column through which carbon dioxide free air and pure nitrogen flowed. The volatilization-to-biodegradation ratios of BTX were 6:1, 2:1 and 2:1 respectively. After 3 weeks, the final concentration in the soil gas was 0.128 mg/L benzene, 0.377 mg/L toluene and 0.143 mg/L xylene. The substrate interactions that occurred were as follows: benzene and xylene degradation was accelerated while toluene was being degraded; and, the presence of xylene increased the lag period for benzene degradation. It was concluded that bioventing is an effective remediation technology for aromatic hydrocarbons and can significantly reduce the remediation time if target residual BTX concentration of 0.1 mg/L is to be reached. BTX removal becomes more significant with time, particularly when soils are inoculated with indigenous microbial communities from contaminated soil. 22 refs., 5 tabs., 7 figs.

  8. The unusual state of the cumulus oophorus and of sperm behaviour within it, in the musk shrew, Suncus murinus.

    Science.gov (United States)

    Bedford, J M; Mori, T; Oda, S

    1997-05-01

    In the musk shrew, Suncus murinus, the behaviour of the cumulus-egg complex and its interaction with spermatozoa were unusual in several respects. The cumulus oophorus was ovulated about 15.5 h after mating or treatment with hCG as a hyaluronidase-insensitive matrix-free ball of cells which remained for relatively long periods of about 14 h around fertilized, and for about 24 h around unfertilized eggs. As a probable function of the small number of up to about 10 or 20 spermatozoa that generally reached the oviduct ampulla from isthmic crypts, there was often a delay of up to 10 h after ovulation before most eggs were penetrated. Soon after ovulation, however, the corona radiata retreated progressively from the zona pellucida, creating a closed perizonal space within the cumulus oophorus. Usually, most spermatozoa that did reach the ampulla were found within a cumulus and generally within that perizonal space. However, whereas the acrosome was intact among the few free ampullary spermatozoa, and in those adhering to the zona of cumulus-free eggs after delayed mating, all spermatozoa seen moving within the cumulus or adhering to the zona of unfertilized eggs had shed the giant acrosome. In accord with current observations in other shrews, the cumulus in Suncus may therefore function not only to sequester spermatozoa, but also as an essential mediator of fertilization-probably by inducing the acrosome reaction. In the absence of the acrosomal carapace that expresses the zona receptors in most mammals, fertilizing Suncus spermatozoa could use an unusual array of barbs on the exposed perforatorium to attach to the zona pellucida.

  9. Evaluating the efficiency of two phase partitioning stirred tank bio-reactor for treating xylene vapors from the airstreamthrough a bed of Pseudomonas Putida

    Directory of Open Access Journals (Sweden)

    F. Golbabaei

    2015-04-01

    Conclusion: Overall, the results of the present research revealed that the application of two phase stirred tank bioreactors (TPPBs containing pure strains of Pseudomonas putida was successful for treatment of air streams with xylene.

  10. Liquid dish washing soap: An excellent substitute for xylene and alcohol in hematoxylin and eosin staining procedure

    Directory of Open Access Journals (Sweden)

    Surekha Ramulu

    2012-01-01

    Full Text Available Aims: Liquid dish washing solution (DWS was used as a substitute for xylene to dewax tissue sections during hematoxylin and eosin (H and E staining. The aim was to test and compare the hypothesis that xylene-ethanol free (XEF sections deparaffinized with diluted DWS are better than or at par with the conventional H and E sections. Materials and Methods: Fifty paraffin-embedded tissue blocks was included. One section was stained with conventional HandE (group A and the other with XEF HandE (group B staining method. Slides were scored for parameters: nuclear, cytoplasmic, clarity, uniformity, and crispness of staining. Z test was used for statistical analysis. For accuracy of diagnosis, sensitivity, specificity, positive predictive value, and negative predictive value were tested. Results: Adequate nuclear staining was noted in 94% in group A and 96% in group B, -adequate cytoplasmic staining in 92% in group A and 86% in group B, clarity in 94% of group A and 96% of group B sections, uniform staining in 92% of group A and 80% of group B sections, crisp stain in 96% of group A and 88% of group B sections, and 94% of group A sections stained adequately for diagnosis as compared with 90% in group B sections. Conclusion: Liquid DWS can be used as an alternative and effective substitute to xylene and ethanol in routine HandE staining procedure.

  11. Evaluating the impact of water supply strategies on p-xylene biodegradation performance in an organic media-based biofilter.

    Science.gov (United States)

    Gallastegui, G; Muñoz, R; Barona, A; Ibarra-Berastegi, G; Rojo, N; Elías, A

    2011-01-30

    The influence of water irrigation on both the long-term and short-term performance of p-xylene biodegradation under several organic loading scenarios was investigated using an organic packing material composed of pelletised sawdust and pig manure. Process operation in a modular biofilter, using no external water supply other than the moisture from the saturated inlet air stream, showed poor p-xylene abatement efficiencies (≈33 ± 7%), while sustained irrigation every 25 days rendered a high removal efficiency (RE) for a critical loading rate of 120 g m(-3)h(-1). Periodic profiles of removal efficiency, temperature and moisture content were recorded throughout the biofilter column subsequent to each biofilter irrigation. Hence, higher p-xylene biodegradation rates were always initially recorded in the upper module, which resulted in a subsequent increase in temperature and a decrease in moisture content. This decrease in the moisture content in the upper module resulted in a higher removal rate in the middle module, while the moisture level in the lower module steadily increased as a result of water condensation. Based on these results, mass balance calculations performed using measured bed temperatures and relatively humidity values were successfully used to account for water balances in the biofilter over time. Finally, the absence of bed compaction after 550 days of continuous operation confirmed the suitability of this organic material for biofiltration processes. Copyright © 2010 Elsevier B.V. All rights reserved.

  12. Catalytic para-xylene maximization. Part X: Toluene disproportionation on HF promoted H-ZSM-5 catalysts

    Directory of Open Access Journals (Sweden)

    Ahmed K. Aboul-Gheit

    2012-12-01

    Full Text Available H-ZSM-5 zeolite catalysts were doped with 2%, 3% and 4%HF to be used for investigating their activities and selectivities for xylenes production and for para-xylene maximization at temperatures of 300–500 °C via toluene disproportionation. This doping caused pore size modification of the H-ZSM-5 catalyst. The reaction was carried out in a fixed bed flow type reactor. The ratio of produced para-xylene relative to its thermodynamic composition reached as high as 3.29 at 300 °C on the 4%HF doped H-ZSM-5 catalyst although this catalyst possessed the lowest amount of the largest pores (3.0–5.7 nm and the smallest pores (0.4–1.7 nm. The overall activities of the catalysts were decreased with an increase in HF doping because of diffusion restriction. The kinetics of the reaction were simply treated and found to give Ea and ΔS∗ values compatible with the characterization data of the catalysts.

  13. Decomposition Characteristics of Benzene, Toluene and Xylene in an Atmospheric Pressure DC Corona Discharge II. Characteristics of Deposited By-products and Decomposition Process

    OpenAIRE

    SAKAI, Seiji; TAKAHASHI, Kazuhiro; SATOH, Kohki; ITOH, Hidenori

    2016-01-01

    Gaseous by-products and deposited material obtained from the decomposition of benzene, toluene and xylene in an atmospheric pressure DC corona discharge were minutely investigated by gas chromatograph mass spectrometry and infrared absorption spectroscopy, and the decomposition processes of benzene, toluene and xylene were estimated. It was found that carbon dioxide (CO2), carbon monoxide (CO), formic acid (HCOOH) and formic anhydride ((CHO)2) were the major gaseous by-products from benzene, ...

  14. Early Liver and Kidney Dysfunction Associated with Occupational Exposure to Sub-Threshold Limit Value Levels of Benzene, Toluene, and Xylenes in Unleaded Petrol.

    Science.gov (United States)

    Neghab, Masoud; Hosseinzadeh, Kiamars; Hassanzadeh, Jafar

    2015-12-01

    Unleaded petrol contains significant amounts of monocyclic aromatic hydrocarbons such as benzene, toluene, and xylenes (BTX). Toxic responses following occupational exposure to unleaded petrol have been evaluated only in limited studies. The main purpose of this study was to ascertain whether (or not) exposure to unleaded petrol, under normal working conditions, is associated with any hepatotoxic or nephrotoxic response. This was a cross-sectional study in which 200 employees of Shiraz petrol stations with current exposure to unleaded petrol, as well as 200 unexposed employees, were investigated. Atmospheric concentrations of BTX were measured using standard methods. Additionally, urine and fasting blood samples were taken from individuals for urinalysis and routine biochemical tests of kidney and liver function. The geometric means of airborne concentrations of BTX were found to be 0.8 mg m(-3), 1.4 mg m(-3), and 2.8 mg m(-3), respectively. Additionally, means of direct bilirubin, alanine aminotransferase, aspartate aminotransferase, blood urea and plasma creatinine were significantly higher in exposed individuals than in unexposed employees. Conversely, serum albumin, total protein, and serum concentrations of calcium and sodium were significantly lower in petrol station workers than in their unexposed counterparts. The average exposure of petrol station workers to BTX did not exceed the current threshold limit values (TLVs) for these chemicals. However, evidence of subtle, subclinical and prepathologic early liver and kidney dysfunction was evident in exposed individuals.

  15. Cobalt oxide nanoparticles as a novel high-efficiency fiber coating for solid phase microextraction of benzene, toluene, ethylbenzene and xylene from aqueous solutions

    International Nuclear Information System (INIS)

    Gholivand, Mohammad Bagher; Shamsipur, Mojtaba; Shamizadeh, Mohammad; Moradian, Rostam; Astinchap, Bandar

    2014-01-01

    Highlights: • Co 3 O 4 nanoparticles were introduced as a novel SPME fiber coating. • The fiber was evaluated for the extraction of BTEX in combination with GC–MS. • The fiber showed extraction efficiencies better than a PDMS fiber toward BTEX. • The fiber was successfully applied to the determination of BTEX in real samples. - Abstract: In this work cobalt oxide nanoparticles were introduced for preparation of a novel solid phase microextraction (SPME) fiber coating. Chemical bath deposition (CBD) technique was used in order for synthesis and immobilization of the Co 3 O 4 nanomaterials on a Pt wire for fabrication of SPME fiber. The prepared cobalt oxide coating was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The fiber was evaluated for the extraction of benzene, toluene, ethylbenzene and xylene (BTEX) in combination with GC–MS. A simplex optimization method was used to optimize the factors affecting the extraction efficiency. Under optimized conditions, the proposed fiber showed extraction efficiencies comparable to those of a commercial polydimethylsiloxane (PDMS) fiber toward the BTEX compounds. The repeatability of the fiber and its reproducibility, expressed as relative standard deviation (RSD), were lower than about 11%. No significant change was observed in the extraction efficiency of the new SPME fiber after over 50 extractions. The fiber was successfully applied to the determination of BTEX compounds in real samples. The proposed nanostructure cobalt oxide fiber is a promising alternative to the commercial fibers as it is robust, inexpensive and easily prepared

  16. Investigating the effect of gas flow rate, inlet ozone concentration and relative humidity on the efficacy of catalytic ozonation process in the removal of xylene from waste airstream

    Directory of Open Access Journals (Sweden)

    H.R. MokaramI

    2010-10-01

    Full Text Available Background and aimsThe catalytic ozonation is an efficient process for the degradation of volatile organic compounds from contaminated air stream. This study was aimed at investigating the efficacy of catalytic ozonation process in removal of xylene from the polluted air stream andthe influence of retention time (gas flow rate, inlet ozone dose and relative humidity on this performanceMethodsthe catalytic ozonation of xylene was conducted using a bench scale set-up consisted of a syringe pump,an air pump, an ozone generator, and a glass reactor packed with activated carbon. Several experimental run was defined to investigate the influence of the selectedoperational variables.ResultsThe results indicated that the efficiency of catalytic ozonation was greater than that of single adsorption in removal of xylene under similar inlet concentration and relative humidity. We found a significant catalytic effect for activated carbon when used in combination with ozonation process, leading to improvement of xylene removal percentage. In addition, the elimination capacity of the system improved with the increase of inlet ozone dose as well as gas flow rate. The relative humidity showed a positive effect of the xylene removal at the range of 5 to 50%, while the higher humidity (more than 50% resulted in reduction of the performance.ConclusionThe findings of the present work revealed that the catalytic ozonation process can be an efficient technique for treating the air streams containing industrial concentrations of xylene. Furthermore, there is a practical potential to retrofit the present adsorption systems intothe catalytic ozonation simply by coupling them with the ozonation system. the catalytic ozonation of xylene was conducted using a bench scale set-up consisted of a syringe pump,an air pump, an ozone generator, and a glass reactor packed with activated carbon. Several experimental run was defined to investigate the influence of the selected

  17. Evaluation of the occupational risk for exposition to Benzene, Toluene and Xylene in a paintings industry in Bogota

    International Nuclear Information System (INIS)

    Rubiano D, Maria del Pilar; Marciales C, Clara; Duarte A, Martha

    2002-01-01

    It was determined Benzene, Toluene and Xylene (BTX) levels in air from paint manufacture assigned to Instituto Colombiano de Seguro Social with the purpose to evaluate the occupational hazard caused by the use of these solvents. These results were compared with the threshold limit value (TLV). It was selected as sampling strategy, the methodology of partial period with consecutive samples and charcoal tubes as adsorbent of solvents. The extraction was realized with carbon disulfide and it was used gas chromatography with FID as analysis method. It was found that the method is highly selective because in presence of the others ten solvents, utilized in paint manufacture, were obtained a good separation for BTX. The precision, expressed a variance coefficient, was lower than 10%, the accuracy varied between 85 and 99 % for the three solvents. The airborne concentration found was between no detectable and 55,1 mg/m 3 for benzene, 18,3 and 253 mg/m 3 for toluene and 11,8 and 122,2 mg/m 3 for xylene. The corrected TLV values for benzene, toluene and xylenes according to the brief and scale model for the ten hours shift were 1,1, 132 and 304 mg/m 3 respectively. It was found occupational risk for benzene in some workplaces; this one is worried because benzene is not used as raw material for the paint manufacture. It was determinate that exist occupational risk in almost every workplace of the industry when it is considered the mixture of the three solvents

  18. An analysis of factors that influence personal exposure to toluene and xylene in residents of Athens, Greece

    Directory of Open Access Journals (Sweden)

    Linos Athena

    2006-02-01

    Full Text Available Abstract Background Personal exposure to pollutants is influenced by various outdoor and indoor sources. The aim of this study was to evaluate the exposure of Athens citizens to toluene and xylene, excluding exposure from active smoking. Methods Passive air samplers were used to monitor volunteers, their homes and various urban sites for one year, resulting in 2400 measurements of toluene and xylene levels. Since both indoor and outdoor pollution contribute significantly to human exposure, volunteers were chosen from occupational groups who spend a lot of time in the streets (traffic policemen, bus drivers and postmen, and from groups who spend more time indoors (teachers and students. Data on individual and house characteristics were obtained using a questionnaire completed at the beginning of the study; a time-location-activity diary was also completed daily by the volunteers in each of the six monitoring campaigns. Results Average personal toluene exposure varied over the six monitoring campaigns from 53 to 80 μg/m3. Urban and indoor concentrations ranged from 47 – 84 μg/m3 and 30 – 51 μg/m3, respectively. Average personal xylene exposure varied between 56 and 85 μg/m3 while urban and indoor concentrations ranged from 53 – 88 μg/m3 and 27 – 48 μg/m3, respectively. Urban pollution, indoor residential concentrations and personal exposures exhibited the same pattern of variation during the measurement periods. This variation among monitoring campaigns might largely be explained by differences in climate parameters, namely wind speed, humidity and amount of sunlight. Conclusion In Athens, Greece, the time spent outdoors in the city center during work or leisure makes a major contribution to exposure to toluene and xylene among non-smoking citizens. Indoor pollution and means of transportation contribute significantly to individual exposure levels. Other indoor residential characteristics such as recent painting and mode of heating

  19. Highly efficient high-performance liquid chromatographic separation of xylene isomers and phthalate acid esters on a homemade DUT-67(Zr) packed column.

    Science.gov (United States)

    Chen, Sha; Li, Xiao-Xin; Feng, Fan; Li, Sumei; Han, Jia-Hui; Jia, Zi-Yi; Shu, Lun; Somsundaran, P; Li, Jian-Rong

    2018-04-16

    In this study, the baseline separations of xylene isomers and phthalate acid esters on a homemade DUT-67(Zr) packed column were achieved, respectively. The high selectivity for xylene isomers and phthalate acid esters was obtained with the increase of temperature and decrease of the retention time. The hydrophobicity of xylene isomers and phthalate acid esters caused the different separation time on the DUT-67(Zr) packed column. The relative standard deviation values of retention time, peak area, peak height and half peak width for five repeat separation of the xylene isomers were 0.26-0.35, 2.11-2.26, 1.51-2.03, and 0.29-0.77%, and the values of the phthalate acid esters on DUT-67(Zr) column were 0.1-0.4, 4.4-5.2, 3.9-6.3, and 0.6-2.1%, respectively. The thermodynamic properties indicated that the separation of xylene isomers was controlled by ΔH and ΔS, but the separation of phthalate acid esters was mainly controlled by ΔS. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  20. Significant changes in the amounts of neurotransmitter and related substances in rat brain induced by subacute exposure to low levels of toluene and xylene

    Energy Technology Data Exchange (ETDEWEB)

    Honma, T.; Sudo, A.; Miyagawa, M.; Sato, M.; Hasegawa, H.

    1983-01-01

    Rats were exposed to toluene and xylene at 200-800 ppm for 30 days. After exposure, changes in the dopamine, norepinephrine, serotonin, acetylcholine (ACh), cyclic AMP, cyclic GMP, GABA, glutamic acid, glutamine, aspartic acid, taurine, glycine and alanine content of different areas of the brain were investigated. ACh in the striatum and whole brain were reduced dose-dependently by toluene and xylene. The reduction at 800 ppm of the solvents was in the range of 10 to 20% of the ACh content of the control rats. Toluene and xylene caused different changes in monoamine content other than ACh, but the changes were not dose-dependent. Among the seven free amino acids that are the main amino acid components of the brain, the glutamine content was increased by toluene and xylene at 800 ppm. Decrease in ACh and increase in glutamine in the brain appear to be phenomena common to many kinds of organic solvents including toluene and xylene after acute and subacute exposure.

  1. In vitro cell culture, platelet adhesion tests and in vivo implant tests of plasma-polymerized para-xylene films

    International Nuclear Information System (INIS)

    Chou, Chia-Man; Yeh, Chou-Ming; Chung, Chi-Jen; He, Ju-Liang

    2013-01-01

    Plasma-polymerized para-xylene (PPX) was developed in a previous study by adjusting the process parameters: pulse frequency of the power supply (ω p ) and para-xylene monomer flow rate (f p ). All the obtained PPX films exhibit an amorphous structure and present hydrophobicity (water contact angle ranging from 98.5° to 121.1°), higher film growth rate and good fibroblast cell proliferation. In this study, in vitro tests (fibroblast cell compatibility and platelet adhesion) and an in vivo animal study were performed by using PPX deposited industrial-grade silicone sheets (IGS) and compared with medical-grade silicone ones (MS), which were commonly manufactured into catheters or drainage tubes in clinical use. The results reveal that PPX deposited at high ω p or high f p , in comparison with MS, exhibit better cell proliferation and clearly shows less cell adhesion regardless of ω p and f p . PPX also exhibit a comparatively lower level of platelet adhesion than MS. In the animal study, PPX-coated IGS result in similar local tissue responses at 3, 7 and 28 days (short-term) and 84 days (long-term) after subcutaneous implantation the abdominal wall of rodents compared with respective responses to MS. These results suggest that PPX-coated industrial-grade silicone is one alternative to high cost medical-grade silicone.

  2. In vitro cell culture, platelet adhesion tests and in vivo implant tests of plasma-polymerized para-xylene films

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Chia-Man [Department of Surgery, Taichung Veterans General Hospital, Taiwan, ROC (China); National Yang-Ming University, Taipei, Taiwan, ROC (China); Yeh, Chou-Ming, E-mail: cmchou4301@gmail.com [Taichung Hospital, Department of Health, Executive Yuan, Taiwan, ROC (China); Chung, Chi-Jen [Department of Dental Technology and Materials Science, Central Taiwan University of Science and Technology, Taiwan, ROC (China); He, Ju-Liang [Department of Materials Science and Engineering, Feng Chia University, Taiwan, ROC (China)

    2013-09-01

    Plasma-polymerized para-xylene (PPX) was developed in a previous study by adjusting the process parameters: pulse frequency of the power supply (ω{sub p}) and para-xylene monomer flow rate (f{sub p}). All the obtained PPX films exhibit an amorphous structure and present hydrophobicity (water contact angle ranging from 98.5° to 121.1°), higher film growth rate and good fibroblast cell proliferation. In this study, in vitro tests (fibroblast cell compatibility and platelet adhesion) and an in vivo animal study were performed by using PPX deposited industrial-grade silicone sheets (IGS) and compared with medical-grade silicone ones (MS), which were commonly manufactured into catheters or drainage tubes in clinical use. The results reveal that PPX deposited at high ω{sub p} or high f{sub p}, in comparison with MS, exhibit better cell proliferation and clearly shows less cell adhesion regardless of ω{sub p} and f{sub p}. PPX also exhibit a comparatively lower level of platelet adhesion than MS. In the animal study, PPX-coated IGS result in similar local tissue responses at 3, 7 and 28 days (short-term) and 84 days (long-term) after subcutaneous implantation the abdominal wall of rodents compared with respective responses to MS. These results suggest that PPX-coated industrial-grade silicone is one alternative to high cost medical-grade silicone.

  3. Utilization of alternative fuels and materials in cement kiln towards emissions of benzene, toluene, ethyl-benzene and xylenes (BTEX

    Directory of Open Access Journals (Sweden)

    Muliane Ulfi

    2018-01-01

    Full Text Available Co-processing in cement industry has benefits for energy conservation and waste recycling. Nevertheless, emissions of benzene, toluene, ethyl-benzene, and xylenes (BTEX tend to increase compared to a non co-processing kiln. A study was conducted in kiln feeding solid AFR (similar to municipal solid waste, MSW having production capacity 4600-ton clinker/day (max. 5000 ton/day and kiln feeding biomass having production capacity 7800-ton clinker/day (max. 8000 ton/day. The concentration of VOCs emissions tends to be higher at the raw mill on rather than the raw mill off. At the raw mill on, concentration of total volatile organic carbon (VOCs emission from cement kiln stack feeding Solid AFR 1, biomass, Solid AFR 2, and mixture of Solid AFR and biomass is 16.18 mg/Nm3, 16.15 mg/Nm3, 9.02 mg/Nm3, and 14.11 mg/Nm3 respectively. The utilization of biomass resulted in the lower fraction of benzene and the higher fraction of xylenes in the total VOCs emission. Operating conditions such as thermal substitution rate, preheater temperature, and kiln speed are also likely to affect BTEX emissions.

  4. Accumulation and turnover of metabolites of toluene and xylene in nasal mucosa and olfactory bulb in the mouse

    International Nuclear Information System (INIS)

    Ghantous, H.; Dencker, L.; Danielsson, B.R.G; Gabrielsson, J.; Bergman, K.

    1990-01-01

    Autoradiography of male mice following inhalation of the radioactively labelled solvents, toluene, xylene, and styrene, revealed an accumulation of non-volatile metabolites in the nasal mucosa and olfactory bulb of the brain. Since no accumulation occurred after benzene inhalation, it was assumed that the activity represented aromatic acids, which are known metabolites of these solvents. This was supported by the finding that also radioactive benzoic acid (main metabolite of toluene) and salicylic acid accumulated in the olfactory bulb. High-performance liquid chromatography revealed that after toluene inhalation (for 1 hr), nasal mucosa and olfactory bulb contained mainly benzoic acid, with a strong accumulation in relation to blood plasma, and considerably less of its blycine conjugate, hippuric acid. After xylene inhalation, on the other hand, methyl hippuric acid dominated over the non-conjugated metabolite, toluic acid. The results indicate a specific, possibly axonal flow-mediated transport of aromatic acids from the nasal mucosa to the olfactory lobe of the brain. The toxicological significance of these results remains to be studied. (author)

  5. Bone pain caused by swelling of mouse ear capsule static xylene and effects on rat models of cervical spondylosis

    Science.gov (United States)

    Zhang, Xuhui; Xia, Lei; Hao, Shaojun; Chen, Weiliang; Guo, Junyi; Ma, Zhenzhen; Wang, Huamin; Kong, Xuejun; Wang, Hongyu; Zhang, Zhengchen

    2018-04-01

    To observe the effect of intravenous bone pain Capsule on the ear of mice induced by xylene, swelling of rat models of cervical spondylosis. Weighing 18 ˜ 21g 50 mice, male, were randomly divided into for five groups, which were fed with service for bone pain static capsule suspension, Jingfukang granule suspension 0.5%CMC liquid and the same volume of. Respectively to the mice ear drop of xylene 0.05 ml, 4h after cervical dislocation, the mice were sacrificed and the cut two ear, rapid analytical balance weighing, and calculate the ear swelling degree and the other to take the weight of 200 - 60 250g male SD rats, were randomly divided into for 6 groups, 10 rats in each group, of which 5 groups made cervical spondylosis model. Results: with the blank group than bone pain static capsule group and Jingfukang granule group can significantly reduce mouse auricular dimethylbenzene swelling, significantly reduce ear swelling degree (P cervical spondylosis. With the model group ratio, large, medium and small dose of bone pain static capsule group, Jingfukang granule group (P pain static capsule group, Jingfukang granule group can significantly reduce the rat X-ray scores (P pain static capsule can significantly reduce mouse auricular dimethylbenzene swelling. The bone pain capsule has a good effect on the rat model of cervical spondylosis.

  6. An isotope dilution gas chromatography/mass spectrometry method for trace analysis of xylene and its metabolites in tissues following threshold limit value exposures

    Energy Technology Data Exchange (ETDEWEB)

    Pyon, K.H.; Kracko, D.A.; Strunk, M.R. [and others

    1995-12-01

    The existence of a nose-brain barrier that functions to protect the central nervous system (CNS) from inhaled toxicants has been postulated. Just as a blood-brain barrier protects the CNS from systemic toxicants, the nose-brain barrier may have similar characteristic functions. One component of interest is nasal xenobiotic metabolism and its effect on the transport of pollutants into the CNS at environmentally plausible levels of exposure. Previous results have shown that inhaled xylene are dimethyl phenol (DMP) and methyl benzyl alcohol (MBA), and the nonvolatile metabolites are toluic acid (TA) and methyl hippuric acid (MHA). The nonvolatile metabolites of xylene, along with a small quantity of volatiles, representing either parent xylene or volatile metabolites, are transported via the olfactory epithelium to the glomeruli within the olfactory bulbs of the brain. Further work will be done to establish the linearity for each analyte at the actual highest detection limit of the GC/MS.

  7. An isotope dilution gas chromatography/mass spectrometry method for trace analysis of xylene and its metabolites in tissues following threshold limit value exposures

    International Nuclear Information System (INIS)

    Pyon, K.H.; Kracko, D.A.; Strunk, M.R.

    1995-01-01

    The existence of a nose-brain barrier that functions to protect the central nervous system (CNS) from inhaled toxicants has been postulated. Just as a blood-brain barrier protects the CNS from systemic toxicants, the nose-brain barrier may have similar characteristic functions. One component of interest is nasal xenobiotic metabolism and its effect on the transport of pollutants into the CNS at environmentally plausible levels of exposure. Previous results have shown that inhaled xylene are dimethyl phenol (DMP) and methyl benzyl alcohol (MBA), and the nonvolatile metabolites are toluic acid (TA) and methyl hippuric acid (MHA). The nonvolatile metabolites of xylene, along with a small quantity of volatiles, representing either parent xylene or volatile metabolites, are transported via the olfactory epithelium to the glomeruli within the olfactory bulbs of the brain. Further work will be done to establish the linearity for each analyte at the actual highest detection limit of the GC/MS

  8. Ionic liquid-based single-drop microextraction/gas chromatographic/mass spectrometric determination of benzene, toluene, ethylbenzene and xylene isomers in waters.

    Science.gov (United States)

    Aguilera-Herrador, Eva; Lucena, Rafael; Cárdenas, Soledad; Valcárcel, Miguel

    2008-08-01

    The direct coupling between ionic liquid-based single-drop microextraction and gas chromatography/mass spectrometry is proposed for the rapid and simple determination of benzene, toluene, ethylbenzene and xylenes isomers (BTEX) in water samples. The extraction procedure exploits not only the high affinity of the selected ionic liquid (1-methyl-3-octyl-imidazolium hexaflourophosphate) to these aromatic compounds but also its special properties like viscosity, low vapour pressure and immiscibility with water. All the variables involved in the extraction process have been studied in depth. The developed method allows the determination of these single-ring compounds in water under the reference concentration level fixed by the international legislation. In this case, limits of detection were in the range 20 ng L(-1) (obtained for benzene) and 91 ng L(-1) (for o-xylene). The repeatability of the proposed method, expressed as RSD (n=5), varied between 3.0% (o-xylene) and 5.2% (toluene).

  9. Environmental exposure of pharmaceuticals and musk fragrances in the Somes River before and after upgrading the municipal wastewater treatment plant Cluj-Napoca, Romania.

    Science.gov (United States)

    Moldovan, Zaharie; Chira, Romeo; Alder, Alfredo C

    2009-08-01

    ), cyclophosphamide (cytostatic), ibuprofen (analgesic), and galaxolide (musk fragrance), were determined in samples of the Somes River. The analytes were enriched by solid-phase extraction and subsequently determined by GC/MS. Caffeine, pentoxifylline, and galaxolide were determined underivatized, whereas the acidic pharmaceuticals carbamazepine, cyclophosphamide, and ibuprofen were determined after derivatization with N-methyl-N-(trimethylsilyl)-trifluoroacetamide. The concentrations in the Somes River varied from below 10 ng/L up to 10 microg/L. A substantial decrease of the exposure in the Somes River could be observed due to the upgrade of the municipal WWTP in Cluj-Napoca. The loads in the river stretch between Cluj-Napoca and Dej (Somes Mic) varied strongly: caffeine (400-2,000 g/day), carbamazepine (78-213 g/day), galaxolide (140-684 g/day), ibuprofen (84-108 g/day). After the upgrade of the WWTP Cluj-Napoca, the concentrations in the Somes of caffeine, pentoxifylline, cyclophosphamide, galaxolide, and tonalide were significantly reduced (over 75%). One might be cautious comparing both studies because the relative efficiency of the WWTP's removal of PPCP was not evaluated. However, the significantly lower concentrations of most compounds after the upgrade of the WWTP Cluj-Napoca allow one to infer that the technical measures at the source substantially reduced inputs of contaminants to the receiving river. Dej loads of the poorly biodegradable substance carbamazepine increased by a factor of 2-3 as a result of wastewater discharges into the river. The disproportionate increase in caffeine loads by a factor of 4 below Cluj-Napoca indicates inputs of untreated wastewater from the Somes Mare due to the discharge of untreated wastewater derived from Bistrita, Nasaud, and Beclean (115,000 inhabitants). The relative contribution of treated and untreated wastewater in surface water might be assessed by measuring chemical markers. Recalcitrant pharmaceuticals like carbamazepine are

  10. Cobalt oxide nanoparticles as a novel high-efficiency fiber coating for solid phase microextraction of benzene, toluene, ethylbenzene and xylene from aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Gholivand, Mohammad Bagher, E-mail: MB.Gholivand@yahoo.com [Department of Analytical Chemistry, Faculty of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Shamsipur, Mojtaba; Shamizadeh, Mohammad [Department of Analytical Chemistry, Faculty of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Moradian, Rostam; Astinchap, Bandar [Physics Department, Faculty of Science, Razi University, Kermanshah (Iran, Islamic Republic of); Nano Technology Research Laboratory, Razi University, Kermanshah (Iran, Islamic Republic of)

    2014-04-01

    Highlights: • Co{sub 3}O{sub 4} nanoparticles were introduced as a novel SPME fiber coating. • The fiber was evaluated for the extraction of BTEX in combination with GC–MS. • The fiber showed extraction efficiencies better than a PDMS fiber toward BTEX. • The fiber was successfully applied to the determination of BTEX in real samples. - Abstract: In this work cobalt oxide nanoparticles were introduced for preparation of a novel solid phase microextraction (SPME) fiber coating. Chemical bath deposition (CBD) technique was used in order for synthesis and immobilization of the Co{sub 3}O{sub 4} nanomaterials on a Pt wire for fabrication of SPME fiber. The prepared cobalt oxide coating was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The fiber was evaluated for the extraction of benzene, toluene, ethylbenzene and xylene (BTEX) in combination with GC–MS. A simplex optimization method was used to optimize the factors affecting the extraction efficiency. Under optimized conditions, the proposed fiber showed extraction efficiencies comparable to those of a commercial polydimethylsiloxane (PDMS) fiber toward the BTEX compounds. The repeatability of the fiber and its reproducibility, expressed as relative standard deviation (RSD), were lower than about 11%. No significant change was observed in the extraction efficiency of the new SPME fiber after over 50 extractions. The fiber was successfully applied to the determination of BTEX compounds in real samples. The proposed nanostructure cobalt oxide fiber is a promising alternative to the commercial fibers as it is robust, inexpensive and easily prepared.

  11. Demonstration of In situ Anaerobic Transformation of Toluene and Xylene Using Single-Well Push-Pull Tests and Deuterated BTEX Surrogates

    Science.gov (United States)

    Field, J. A.; Reusser, D. E.; Beller, H. R.; Istok, J. D.

    2001-12-01

    Obtaining unambiguous evidence of in-situ transformation of benzene, toluene, ethylbenzene and xylene (BTEX) in the subsurface is a difficult task. Recently, benzylsuccinic acid and its methyl analogues were shown to be unequivocal degradation products of anaerobic toluene and xylene biodegradation. Conducting tracer tests at BTEX-contaminated field sites is problematic because background contaminant concentrations potentially interfere with the interpretation of field test data. To avoid the time and cost associated with removing background contaminants, alternative approaches are needed. Deuterated analogs of toluene and xylene are well-suited for use in field tracer tests because they are inexpensive and can be distinguished analytically from background toluene and xylene. In this study, single-well push-pull tests, in which deuterated toluene and xylene were injected, were performed to assess the in-situ anaerobic biotransformation of toluene and xylene in BTEX-contaminated wells. A total of 4 single-well push-pull tests were conducted at BTEX-contaminated field sites near Portland, OR and Kansas City, KS. Test solutions consisting of 100 mg/L bromide, 250 mg/L nitrate, 0.4 to 2.5 mg/L toluene-d8, and 0.4 to 1.0 mg/L o-xylene-d10.were injected at a rate of 0.5 - 2 L/min. During the extraction phase, samples were taken daily to biweekly for up to 30 days. Samples for volatile organic analytes were collected in 40-mL volatile organic analysis (VOA) vials without headspace. Samples for BSA and methyl-BSA were collected in 1 L glass bottles and preserved with 5% (w/w) formalin. Samples were shipped on ice and stored at 4 C until analysis. Unambiguous evidence of toluene and xylene biotransformation was obtained with the in-situ formation of BSA and methyl-BSA. The concentrations of BSA ranged from below the detection limit (0.2 ug/L) to 1.5 ug/L. The concentrations of methyl-BSA ranged from below detection to the quantitation limit (0.7 ug/L). The highest BSA

  12. Determination of biodegradation process of benzene, toluene, ethylbenzene and xylenes in seabed sediment by purge and trap gas chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Han, Dongqiang [Key Lab. for Atomic and Molecular Nanosciences of Education Ministry, Tsinghua Univ., Beijing (China). Dept. of Physics; China Pharmaceutical Univ., Nanjing (China). Physics Teaching and Research Section, Dept. of Basic Sciences; Ma, Wanyun; Chen, Dieyan [Key Lab. for Atomic and Molecular Nanosciences of Education Ministry, Tsinghua Univ., Beijing (China). Dept. of Physics

    2007-12-15

    Benzene, toluene, ethylbenzene, and xylenes (BTEX) are commonly found in crude oil and are used in geochemical investigations as direct indicators of the presence of oil and gas. BTEX are easily volatile and can be degraded by microorganisms, which affect their precise measurement seriously. A method for determining the biodegradation process of BTEX in seabed sediment using dynamic headspace (purge and trap) gas chromatography with a photoionization detector (PID) was developed, which had a detection limit of 7.3-13.2 ng L{sup -1} and a recovery rate of 91.6-95.0%. The decrease in the concentration of BTEX components was monitored in seabed sediment samples, which was caused by microorganism biodegradation. The results of BTEX biodegradation process were of great significance in the collection, transportation, preservation, and measurement of seabed sediment samples in the geochemical investigations of oil and gas. (orig.)

  13. Biodegradation of Benzene, Toluene, Ethylbenzene, and o-, m-, and p-Xylenes by the Newly Isolated Bacterium Comamonas sp. JB.

    Science.gov (United States)

    Jiang, Bei; Zhou, Zunchun; Dong, Ying; Tao, Wei; Wang, Bai; Jiang, Jingwei; Guan, Xiaoyan

    2015-07-01

    A bacterium designated strain JB, able to degrade six benzene, toluene, ethylbenzene, and o-, m-, and p-xylene (BTEX) compounds, was isolated from petroleum-contaminated soil. Taxonomic analyses showed that the isolate belonged to Comamonas, and until now, the genus Comamonas has not included any known BTEX degraders. The BTEX biodegradation rate was slightly low on the mineral salt medium (MSM), but adding a small amount of yeast extract greatly enhanced the biodegradation. The relationship between specific degradation rate and individual BTEX was described well by Michaelis-Menten kinetics. The treatment of petrochemical wastewater containing BTEX mixture and phenol was shown to be highly efficient by BTEX-grown JB. In addition, toxicity assessment indicated the treatment of the petrochemical wastewater by BTEX-grown JB led to less toxicity than untreated wastewater.

  14. On-line CO, CO2 emissions evaluation and (benzene, toluene, xylene) determination from experimental burn of tropical biomass.

    Science.gov (United States)

    Tawfiq, Mohammed F; Aroua, Mohamed Kheireddine; Sulaiman, Nik Meriam Nik

    2015-07-01

    Atmospheric pollution and global warming issues are increasingly becoming major environmental concerns. Fire is one of the significant sources of pollutant gases released into the atmosphere; and tropical biomass fires, which are of particular interest in this study, contribute greatly to the global budget of CO and CO2. This pioneer research simulates the natural biomass burning strategy in Malaysia using an experimental burning facility. The investigation was conducted on the emissions (CO2, CO, and Benzene, Toluene, Ethylbenzene, Xylenes (BTEX)) from ten tropical biomass species. The selected species represent the major tropical forests that are frequently subjected to dry forest fire incidents. An experimental burning facility equipped with an on-line gas analyzer was employed to determine the burning emissions. The major emission factors were found to vary among the species, and the specific results were as follows. The moisture content of a particular biomass greatly influenced its emission pattern. The smoke analysis results revealed the existence of BTEX, which were sampled from a combustion chamber by enrichment traps aided with a universal gas sampler. The BTEX were determined by organic solvent extraction followed by GC/MS quantification, the results of which suggested that the biomass burning emission factor contributed significant amounts of benzene, toluene, and m,p-xylene. The modified combustion efficiency (MCE) changed in response to changes in the sample moisture content. Therefore, this study concluded that the emission of some pollutants mainly depends on the burning phase and sample moisture content of the biomass. Copyright © 2015. Published by Elsevier B.V.

  15. Kinetics and thermodynamics of β-carotene and chlorophyll adsorption onto acid-activated bentonite from Xinjiang in xylene solution

    International Nuclear Information System (INIS)

    Wu Zhansheng; Li Chun

    2009-01-01

    The kinetics and thermodynamics of β-carotene and chlorophyll adsorption from xylene solution onto acid-activated bentonite (AAB) within the temperature range 65-95 deg. C were investigated. Adsorption of β-carotene was described well with the Langmuir isotherm, whereas chlorophyll adsorption was determined well with the Freundlich isotherm, and the experimental data on chlorophyll adsorption were also fitted by the Langmuir isotherm to a certain extent, as reflected by correlation coefficients (R 2 ) over 0.9865. In addition, the adsorption of β-carotene and chlorophyll onto AAB are favorable. The pseudo-second-order model was found to explain the kinetics of adsorption of both pigments more effectively. Increase of temperature enhanced the adsorption rate and equilibrium adsorption capacity of β-carotene and chlorophyll on AAB. The activation energy for the sorption of β-carotene and chlorophyll on AAB was 19.808 kJ/mol and 16.475 kJ/mol, respectively. The thermodynamic parameters ΔH θ , ΔS θ and ΔG θ , computed from K F of the adsorption isotherm constant, were 21.766 kJ/mol, 92.244 J/K mol and -9.554 kJ/mol respectively for the adsorption of β-carotene on AAB at 65 deg. C, and for adsorption of chlorophyll on AAB at 65 deg. C were 31.051 kJ/mol, 93.549 J/K mol and -0.729 kJ/mol, respectively. The adsorption of β-carotene and chlorophyll in xylene solution on AAB was a spontaneous and endothermic process with increasing in the randomness at the solid-solution interface.

  16. Biomonitoring-based exposure assessment of benzene, toluene, ethylbenzene and xylene among workers at petroleum distribution facilities.

    Science.gov (United States)

    Heibati, Behzad; Godri Pollitt, Krystal J; Charati, Jamshid Yazdani; Ducatman, Alan; Shokrzadeh, Mohammad; Karimi, Ali; Mohammadyan, Mahmoud

    2018-03-01

    Elevated emissions of volatile organic compounds, including benzene, toluene, ethylbenzene, and o, p, and m-xylenes (BTEX), are an occupational health concern at oil transfer stations. This exploratory study investigated personal exposure to BTEX through environmental air and urine samples collected from 50 male workers at a major oil distribution company in Iran. Airborne BTEX exposures were evaluated over 8h periods during work-shift by using personal passive samplers. Urinary BTEX levels were determined using solid-phase microextraction with gas chromatography mass spectrometry for separation and detection. Mean exposure to ambient concentrations of benzene differed by workers' job type: tanker loading workers (5390μg/m 3 ), tank-gauging workers (830μg/m 3 ), drivers (81.9μg/m 3 ), firefighters (71.2μg/m 3 ) and office workers (19.8μg/m 3 ). Exposure across job type was similarly stratified across all personal exposures to BTEX measured in air samples with maximum concentrations found for tanker loading workers. Average exposures concentrations of BTEX measured in urine were 11.83 ppb benzene, 1.87 ppb toluene, 0.43 ppb ethylebenzene, and 3.76 ppb xylene. Personal air exposure to benzene was found to be positively associated with benzene concentrations measured in urine; however, a relationship was not observed to the other BTEX compounds. Urinary exposure profiles are a potentially useful, noninvasive, and rapid method for assessing exposure to benzene in a developing and relatively remote production region. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Substrate Interactions during the Biodegradation of Benzene, Toluene, Ethylbenze, and Xylene (BTEX) Hydrocarbons by the Fungus Cladophialophora sp. Strain T1

    NARCIS (Netherlands)

    Prenafeta-Boldú, F.X.; Vervoort, J.; Grotenhuis, J.T.C.; Groenestijn, van J.W.

    2002-01-01

    The soil fungus Cladophialophora sp. strain T1 (= ATCC MYA-2335) was capable of growth on a model water-soluble fraction of gasoline that contained all six BTEX components (benzene, toluene, ethylbenzene, and the xylene isomers). Benzene was not metabolized, but the alkylated benzenes (toluene,

  18. Concentrations of benzene, toluene, ethylbenzene and o-xylene in soil and atmospheric precipitations in the cities of Almaty and Astana

    Directory of Open Access Journals (Sweden)

    Dina Orazbayeva

    2016-06-01

    Full Text Available BTEX (benzene, toluene, ethylbenzene, xylene is one of the most dangerous groups of organic toxicants in terms of emissions and risks to public health. BTEX are present in almost all technogenic and natural objects. The greatest risk to public health is caused by BTEX contamination of cities characterized by high population densities and emissions to the environment. The aim of this work was to determine the concentrations of benzene, toluene, ethylbenzene and o-xylene in samples of soils and atmospheric precipitations selected in the cities of Almaty and Astana. Screening and quantification of analytes was performed by gas chromatography - mass spectrometry. Solid-phase microextraction was used for sample preparation. In the soil samples collected in the cities of Almaty and Astana, the concentrations of analytes ranged from 29.9 to 455 ng/g for benzene, from 9.9 to 375 ng/g for toluene, from 1.8 to 386 ng/g for ethylbenzene, and from 2.4 to 217 ng/g for o-xylene. Concentrations of BTEX in samples of atmospheric precipitations varied in the range of 8.2-21.2 ng/g for benzene; 0.8-5.1 ng/g for toluene; 0.1-1.1 ng/g for ethylbenzene; and 0.2-0.5 ng/g for o-xylene. BTEX concentrations in analyzed soil samples were in average ten times higher than those measured in European cities.

  19. Structural and energetical studies of the adsorption of para and meta-isomers of xylene on pre-hydrated zeolite BaX. Characterization by neutron diffraction and temperature programmed desorption; Etude structurale et energetique de l'adsorption des isomeres para- et meta- du xylene dans la zeolithe BaX prehydratee. Caracterisation par diffraction des neutrons et thermodesorption programmee

    Energy Technology Data Exchange (ETDEWEB)

    Pichon, Ch.

    1999-10-19

    The separation of p-xylene from C{sub 8} aromatics is performed industrially by selective adsorption on zeolitic materials. FAU-type zeolites are currently used for this separation and especially the partially hydrated BaX. The aim of this work is to characterize from a structural (by low temperature neutron powder diffraction) and an energetical (by temperature programmed desorption) point of view, the adsorption of para- and meta- isomers of xylene, for different fillings, as pure substances as well as mixtures, on pre-hydrated zeolite BaX. The influence of the water pre-adsorption on xylene adsorption selectivity is carefully discussed. The crystalline structure of the zeolite BaX (framework and compensation of charge cations) and of the adsorbed phase (water, p- and m-xylene molecules) are completely characterized by neutron diffraction. The location and the distribution of water and xylene molecules on their adsorption sites is especially followed as a function of the filling of the zeolite and of the composition of the adsorbed phase. Microscopic measurements were correlated to the energetical analysis (at a macroscopic level) in order to obtain a consistent description of adsorption phenomenon and to propose a possible origin for adsorption selectivity.

  20. Graphene-Derivatized Silica Composite as Solid-Phase Extraction Sorbent Combined with GC–MS/MS for the Determination of Polycyclic Musks in Aqueous Samples

    Directory of Open Access Journals (Sweden)

    Cheng Li

    2018-02-01

    Full Text Available Polycyclic musks (PCMs have recently received growing attention as emerging contaminants because of their bioaccumulation and potential ecotoxicological effects. Herein, an effective method for the determination of five PCMs in aqueous samples is presented. Reduced graphene oxide-derivatized silica (rGO@silica particles were prepared from graphene oxide and aminosilica microparticles and characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. PCMs were preconcentrated using rGO@silica as the solid-phase extraction sorbent and quantified by gas chromatography–tandem mass spectrometry. Several experimental parameters, such as eluent, elution volume, sorbent amount, pH, and sample volume were optimized. The correlation coefficient (R ranged from 0.9958 to 0.9992, while the limits of detection and quantitation for the five PCMs were 0.3–0.8 ng/L and 1.1–2.1 ng/L, respectively. Satisfactory recoveries were obtained for tap water (86.6–105.9% and river water samples (82.9–107.1%, with relative standard deviations <10% under optimal conditions. The developed method was applied to analyze PCMs in tap and river water samples from Beijing, China. Galaxolide (HHCB and tonalide (AHTN were the main PCM components detected in one river water sample at concentrations of 18.7 for HHCB, and 11.7 ng/L for AHTN.

  1. Dietary competition between the alien Asian Musk Shrew (Suncus murinus) and a re-introduced population of Telfair's Skink (Leiolopisma telfairii).

    Science.gov (United States)

    Brown, D S; Burger, R; Cole, N; Vencatasamy, D; Clare, E L; Montazam, A; Symondson, W O C

    2014-08-01

    Re-introduction of rare species to parts of their historical range is becoming increasingly important as a conservation strategy. Telfair's Skinks (Leiolopisma telfairii), once widespread on Mauritius, were until recently found only on Round Island. There it is vulnerable to stochastic events, including the introduction of alien predators that may either prey upon it or compete for food resources. Consequently, skinks have been introduced to Ile aux Aigrettes, another small Mauritian island that has been cleared of rats. However, the island has been invaded by Asian Musk Shrews (Suncus murinus), a commensal species spread by man well beyond its natural Asian range. Our aim was to use next-generation sequencing to analyse the diets of the shrews and skinks to look for niche competition. DNA was extracted from skink faeces and from the stomach contents of shrews. Application of shrew- and skink-specific primers revealed no mutual predation. The DNA was then amplified using general invertebrate primers with tags to identify individual predators, and then sequenced by 454 pyrosequencing. 119 prey MOTUs (molecular taxonomic units) were isolated, although none could be identified to species. Seeding of cladograms with known sequences allowed higher taxonomic assignments in some cases. Although most MOTUs were not shared by shrews and skinks, Pianka's niche overlap test showed significant prey overlap, suggesting potentially strong competition where food resources are limited. These results suggest that removal of the shrews from the island should remain a priority. © 2013 John Wiley & Sons Ltd.

  2. Metabolism of the polycyclic musk galaxolide and its interference with endogenous and xenobiotic metabolizing enzymes in the European sea bass (Dicentrarchus labrax)

    International Nuclear Information System (INIS)

    Fernandes, Denise; Dimastrogiovanni, Giorgio; Blázquez, Mercedes; Porte, Cinta

    2013-01-01

    This study investigates the metabolism and mode of action of galaxolide (HHCB) in the European sea bass -Dicentrarchus labrax- following a single intraperitoneal injection of 50 mg HHCB/kg body weight. In addition, a group of fish was injected with 50 mg/kg of ketoconazole (KCZ), a fungicide that is known to interfere with different Cyp isoenzymes. HHCB was actively metabolised by sea bass and acted as a weak inhibitor of the synthesis of oxyandrogens in gonads of male fish. Both, HHCB and a hydroxylated metabolite were detected in bile. The fungicide ketoconazole was a strong inhibitor of Cyp11β and Cyp3a-catalyzed activities. The work contributes to the better understanding of the impact of synthetic musks on fish and proposes the determination of HHCB and/or its hydroxylated metabolite in bile as a tool to assess environmental exposure in wild fish. -- Highlights: ► The metabolism and mode of action of galaxolide has been investigated in sea bass. ► A hydroxylated metabolite was for the first time identified in fish bile. ► EROD and BCOD activities were not altered by galaxolide exposure. ► Galaxolide decreased moderately the synthesis of oxyandrogens in testes. -- HHCB is actively metabolised by sea bass and acts as a weak inhibitor of the synthesis of oxyandrogens in gonads of male fish

  3. Production of Bacillus amyloliquefaciens OG and its metabolites in renewable media: valorisation for biodiesel production and p-xylene decontamination.

    Science.gov (United States)

    Etchegaray, Augusto; Coutte, François; Chataigné, Gabrielle; Béchet, Max; Dos Santos, Ramon H Z; Leclère, Valérie; Jacques, Philippe

    2017-01-01

    Biosurfactants are important in many areas; however, costs impede large-scale production. This work aimed to develop a global sustainable strategy for the production of biosurfactants by a novel strain of Bacillus amyloliquefaciens. Initially, Bacillus sp. strain 0G was renamed B. amyloliquefaciens subsp. plantarum (syn. Bacillus velezensis) after analysis of the gyrA and gyrB DNA sequences. Growth in modified Landy's medium produced 3 main recoverable metabolites: surfactin, fengycin, and acetoin, which promote plant growth. Cultivation was studied in the presence of renewable carbon (as glycerol) and nitrogen (as arginine) sources. While diverse kinetics of acetoin production were observed in different media, similar yields (6-8 g·L -1 ) were obtained after 72 h of growth. Glycerol increased surfactin-specific production, while arginine increased the yields of surfactin and fengycin and increased biomass significantly. The specific production of fengycin increased ∼10 times, possibly due to a connecting pathway involving arginine and ornithine. Adding value to crude extracts and biomass, both were shown to be useful, respectively, for the removal of p-xylene from contaminated water and for biodiesel production, yielding ∼70 mg·g -1 cells and glycerol, which could be recycled in novel media. This is the first study considering circular bioeconomy to lower the production costs of biosurfactants by valorisation of both microbial cells and their primary and secondary metabolites.

  4. Synthesis of Co3O4/TiO2 composite by pyrolyzing ZIF-67 for detection of xylene

    Science.gov (United States)

    Bai, Shouli; Tian, Ke; Tian, Ye; Guo, Jun; Feng, Yongjun; Luo, Ruixian; Li, Dianqing; Chen, Aifan; Liu, Chung Chiun

    2018-03-01

    Co3O4/TiO2 composites with p-n heterojunction have been successfully prepared by pyrolyzing sacrificial template of Ti ion loaded Co-based Zeolitic imidazolate framework (ZIF-67). The structure and morphology of composite have been characterized by means of the analysis of XRD, FESEM, HRTEM and XPS spectra. The composite with a Co/Ti molar ratio of 4:1 exhibits the maximum sensing response of 6.17-50 ppm xylene, which is 5 times higher than pristine Co3O4. Moreover, Co3O4/TiO2 composite also shows good selectivity, long-term stability and rapid response and recovery. Such excellent sensing performances are attributed to material porous structure, high specific surface and the formation of abundant p-n heterojunction that permits the gas adsorption, diffusion and surface reaction and then improve the gas sensing performance. This work develops a promising synthesized approach of metal oxide composites for broader MOFs application in gas sensor field.

  5. Development of a versatile, easy and rapid atmospheric monitor for benzene, toluene, ethylbenzene and xylenes determination in air.

    Science.gov (United States)

    Esteve-Turrillas, Francesc A; Ly-Verdú, Saray; Pastor, Agustín; de la Guardia, Miguel

    2009-11-27

    A new procedure for the passive sampling in air of benzene, toluene, ethylbenzene and xylene isomers (BTEX) is proposed. A low-density polyethylene layflat tube filled with a mixture of solid phases provided a high versatility tool for the sampling of volatile compounds from air. Several solid phases were assayed in order to increase the BTEX absorption in the sampler and a mixture of florisil and activated carbon provided the best results. Direct head-space-gas chromatography-mass spectrometry (HS-GC-MS) measurement of the whole deployed sampler was employed for a fast determination of BTEX. Absorption isotherms were used to develop simple mathematical models for the estimation of BTEX time-weighted average concentrations in air. The proposed samplers were used to determine BTEX in indoor air environments and results were compared with those found using two reference methodologies: triolein-containing semipermeable membrane devices (SPMDs) and diffusive Radiello samplers. In short, the developed sampling system and analytical strategy provides a versatile, easy and rapid atmospheric monitor (VERAM).

  6. Sensing behavior of flower-shaped MoS2 nanoflakes: case study with methanol and xylene.

    Science.gov (United States)

    Barzegar, Maryam; Berahman, Masoud; Iraji Zad, Azam

    2018-01-01

    Recent research interest in two-dimensional (2D) materials has led to an emerging new group of materials known as transition metal dichalcogenides (TMDs), which have significant electrical, optical, and transport properties. MoS 2 is one of the well-known 2D materials in this group, which is a semiconductor with controllable band gap based on its structure. The hydrothermal process is known as one of the scalable methods to synthesize MoS 2 nanostructures. In this study, the gas sensing properties of flower-shaped MoS 2 nanoflakes, which were prepared from molybdenum trioxide (MoO 3 ) by a facile hydrothermal method, have been studied. Material characterization was performed using X-ray diffraction, Brunauer-Emmett-Teller surface area measurements, elemental analysis using energy dispersive X-ray spectroscopy, and field-emission scanning electron microscopy. The gas sensing characteristics were evaluated under exposure to various concentrations of xylene and methanol vapors. The results reveal higher sensitivity and shorter response times for methanol at temperatures below 200 °C toward 200 to 400 ppm gas concentrations. The sensing mechanisms for both gases are discussed based on simulation results using density functional theory and charge transfer.

  7. Dielectric properties of liquid systems: study of interactions in the systems carbon tetrachloride with benzene, toluene, and p-xylene

    Directory of Open Access Journals (Sweden)

    Adrián H. Buep

    2014-12-01

    Full Text Available Intermolecular associations in liquid systems of non-polar and slightly polar compounds were studied through excess molar volumes (VEM and excess dielectric properties (εE and n2ED for mixtures of carbon tetrachloride (CCl4 with benzene (C6H6, toluene (C6H5CH3, and p-xylene (p-(CH32C6H4. These excess properties were calculated from measurements of density (ρ, static permittivity (ε, and refractive index (nD over the whole range of concentrations at 298.15 K. The values of the excess dielectric properties for these mixtures were fitted in two different ways, one through least squares using the Redlich–Kister equation and the other using a model developed to explain deviations from ideality. The first fit was found to be descriptive while the second gave the equilibrium constant values for the interaction products actually formed in the mixtures and the respective electronic polarizabilities and dipole moments, indicating the existence of interaction products.

  8. Efficient visible light photocatalysis of benzene, toluene, ethylbenzene and xylene (BTEX) in aqueous solutions using supported zinc oxide nanorods

    Science.gov (United States)

    Bora, Tanujjal; Al-Abri, Mohammed; Dutta, Joydeep

    2017-01-01

    Benzene, toluene, ethylbenzene and xylenes (BTEX) are some of the common environmental pollutants originating mainly from oil and gas industries, which are toxic to human as well as other living organisms in the ecosystem. Here we investigate photocatalytic degradation of BTEX under visible light irradiation using supported zinc oxide (ZnO) nanorods grown on glass substrates using a microwave assisted hydrothermal method. ZnO nanorods were characterized by electron microscopy, X-ray diffraction (XRD), specific surface area, UV/visible absorption and photoluminescence spectroscopy. Visible light photocatalytic degradation products of BTEX are studied for individual components using gas chromatograph/mass spectrometer (GC/MS). ZnO nanorods with significant amount of electronic defect states, due to the fast crystallization of the nanorods under microwave irradiation, exhibited efficient degradation of BTEX under visible light, degrading more than 80% of the individual BTEX components in 180 minutes. Effect of initial concentration of BTEX as individual components is also probed and the photocatalytic activity of the ZnO nanorods in different conditions is explored. Formation of intermediate byproducts such as phenol, benzyl alcohol, benzaldehyde and benzoic acid were confirmed by our HPLC analysis which could be due to the photocatalytic degradation of BTEX. Carbon dioxide was evaluated and showed an increasing pattern over time indicating the mineralization process confirming the conversion of toxic organic compounds into benign products. PMID:29261711

  9. Integration of processes induced air flotation and photo-Fenton for treatment of residual waters contaminated with xylene.

    Science.gov (United States)

    da Silva, Syllos S; Chiavone-Filho, Osvaldo; de Barros Neto, Eduardo L; Nascimento, Claudio A O

    2012-01-15

    Produced water in oil fields is one of the main sources of wastewater generated in the industry. It contains several organic compounds, such as benzene, toluene, ethyl benzene and xylene (BTEX), whose disposal is regulated by law. The aim of this study is to investigate a treatment of produced water integrating two processes, i.e., induced air flotation (IAF) and photo-Fenton. The experiments were conducted in a column flotation and annular lamp reactor for flotation and photodegradation steps, respectively. The first order kinetic constant of IAF for the wastewater studied was determined to be 0.1765 min(-1) for the surfactant EO 7. Degradation efficiencies of organic loading were assessed using factorial planning. Statistical data analysis shows that H(2)O(2) concentration is a determining factor in process efficiency. Degradations above 90% were reached in all cases after 90 min of reaction, attaining 100% mineralization in the optimized concentrations of Fenton reagents. Process integration was adequate with 100% organic load removal in 20 min. The results of the integration of the IAF with the photo-Fenton allowed to meet the effluent limits established by Brazilian legislation for disposal. Copyright © 2011 Elsevier B.V. All rights reserved.

  10. Co-occurrence of musk fragrances and UV-filters in seafood and macroalgae collected in European hotspots

    NARCIS (Netherlands)

    Cunha, S.C.; Fernandes, J.O.; Vallecillos, L.; Kotterman, M.J.J.

    2015-01-01

    In the last decades, awareness regarding personal care products (PCP), i.e. synthetic organic chemicals frequently used in cosmetic and hygienic products, has become a forward-looking issue, due to their persistency in the environment and their potential multi-organ toxicity in both human and

  11. A comparative study to evaluate liquid dish washing soap as an alternative to xylene and alcohol in deparaffinization and hematoxylin and eosin staining.

    Science.gov (United States)

    Pandey, Pinki; Dixit, Alok; Tanwar, Aparna; Sharma, Anuradha; Mittal, Sanjeev

    2014-07-01

    Our study presents a new deparaffinizing and hematoxylin and eosin (H and E) staining method that involves the use of easily available, nontoxic and eco-friendly liquid diluted dish washing soap (DWS) by completely eliminating expensive and hazardous xylene and alcohol from deparaffinizing and rehydration prior to staining, staining and from dehydration prior to mounting. The aim was to evaluate and compare the quality of liquid DWS treated xylene and alcohol free (XAF) sections with that of the conventional H and E sections. A total of 100 paraffin embedded tissue blocks from different tissues were included. From each tissue block, one section was stained with conventional H and E (normal sections) and the other with XAF H and E (soapy sections) staining method. Slides were scored using five parameters: Nuclear, cytoplasmic, clarity, uniformity, and crispness of staining. Z-test was used for statistical analysis. Soapy sections scored better for cytoplasmic (90%) and crisp staining (95%) with a statistically significant difference. Whereas for uniformity of staining, normal sections (88%) scored over soapy sections (72%) (Z = 2.82, P 0.05). Liquid DWS is a safe and efficient alternative to xylene and alcohol in deparaffinization and routine H and E staining procedure. We are documenting this project that can be used as a model for other histology laboratories.

  12. Improved assignments of the vibrational fundamental modes of ortho -, meta -, and para -xylene using gas- and liquid-phase infrared and Raman spectra combined with ab initio calculations: Quantitative gas-phase infrared spectra for detection

    Energy Technology Data Exchange (ETDEWEB)

    Lindenmaier, Rodica; Scharko, Nicole K.; Tonkyn, Russell G.; Nguyen, Kiet T.; Williams, Stephen D.; Johnson, Timothy J.

    2017-07-25

    Xylenes contain a blend of the ortho-, meta-, and para- isomers, and all are abundant contaminants in the ground, surface waters, and air. To better characterize xylene and to better enable its detection, we report high quality quantitative vapor-phase infrared spectra of all three isomers over the 540-6500 cm-1 range. All fundamental vibrational modes are assigned based on these vapor-phase infrared spectra, liquid-phase infrared and Raman spectra, along with density functional theory (DFT), ab initio MP2 and high energy-accuracy compound theoretical model (W1BD) calculations. Both MP2 and DFT predict a single conformer with C2v symmetry for ortho-xylene, and two conformers each for meta- and para-xylene, depending on the preferred orientations of the methyl groups. For meta-xylene the two conformers have Cs and C2 symmetry, and for para-xylene these conformers have C2v or C2h symmetry. Since the relative population of the two conformers is approximately 50% for both isomers and predicted frequencies and intensities are very similar for each conformer, we made an arbitrary choice to discuss the Cs conformer for meta-xylene and the C2v conformer for para-xylene. We report integrated band intensities for all isomers. Using the quantitative infrared data, we determine the global warming potential values of each isomer and discuss potential bands for atmospheric monitoring.

  13. Evaluation of seawater contamination with benzene, toluene and xylene in the Ubatuba north coast, SP region, and study of their removal by ionizing radiation

    International Nuclear Information System (INIS)

    Almeida, Kelly Cristina Santana de

    2006-01-01

    A major concern with leaking petroleum is the environmental contamination by the toxic and low water-soluble components such as benzene, toluene, and xylenes (BTX). These hydrocarbons have relatively high pollution potential because of their significant toxicity. The objective of this study was to evaluate the contamination of seawater by the main pollutants of the output and transport of petroleum, such as benzene, toluene, and xylene, and their removal by the exposure to the ionizing radiation. The studied region was Ubatuba region, SP, between 23 deg 26'S and 23 deg 46'S of latitude and 45 deg 02'W and 45 deg 11'W of longitude, area of carry and output of petroleum, and samples were collected from November, 2003 to July, 2005. For BTX in seawater analysis, the Purge and Trap concentrator with FIDGC detector showed significantly higher sensibility than Head Space concentrator with MSGC detector. The minimal detected limits (MDL) obtained at FIDGC were of 0.50 μg/L for benzene, 0.70 μg/L for toluene, and 1.54 μg/L for xylene, and the obtained experimental variability was 15%. While the concentrator type Headspace system with MS detector showed higher MLD, about of 9.30 mg/L for benzene, 8.50 mg/L for toluene, and 9.80 mg/L for xylene, and 10% of experimental variability. In the studied area the benzene concentration varied from 1.0 μg/L to 2.0 μg/L, the concentration of toluene varied from 60 Co, presented a removal from 10% to 40% of benzene at 20 kGy absorbed doses and concentration of 35.1 mg/L and 70.2 mg/L, respectively; from 20% to 60% of toluene removal with 15 kGy absorbed dose and from 20% to 80% of xylene with 15 kGy absorbed dose in similar concentrations. (author)

  14. Amine-functionalized MIL-53(Al)-coated stainless steel fiber for efficient solid-phase microextraction of synthetic musks and organochlorine pesticides in water samples.

    Science.gov (United States)

    Xie, Lijun; Liu, Shuqin; Han, Zhubing; Jiang, Ruifen; Zhu, Fang; Xu, Weiqin; Su, Chengyong; Ouyang, Gangfeng

    2017-09-01

    The fiber coating is the key part of the solid-phase microextraction (SPME) technique, and it determines the sensitivity, selectivity, and repeatability of the analytical method. In this work, amine (NH 2 )-functionalized material of Institute Lavoisier (MIL)-53(Al) nanoparticles were successfully synthesized, characterized, and applied as the SPME fiber coating for efficient sample pretreatment owing to their unique structures and excellent adsorption properties. Under optimized conditions, the NH 2 -MIL-53(Al)-coated fiber showed good precision, low limits of detection (LODs) [0.025-0.83 ng L -1 for synthetic musks (SMs) and 0.051-0.97 ng L -1 for organochlorine pesticides (OCPs)], and good linearity. Experimental results showed that the NH 2 -MIL-53(Al) SPME coating was solvent resistant and thermostable. In addition, the extraction efficiencies of the NH 2 -MIL-53(Al) coating for SMs and OCPs were higher than those of commercially available SPME fiber coatings such as polydimethylsiloxane, polydimethylsiloxane-divinylbenzene, and polyacrylate. The reasons may be that the analytes are adsorbed on NH 2 -MIL-53(Al) primarily through π-π interactions, electron donor-electron acceptor interactions, and hydrogen bonds between the analytes and organic linkers of the material. Direct immersion (DI) SPME-gas chromatography-mass spectrometry methods based on NH 2 -MIL-53(Al) were successfully applied for the analysis of tap and river water samples. The recoveries were 80.3-115% for SMs and 77.4-117% for OCPs. These results indicate that the NH 2 -MIL-53(Al) coating may be a promising alternative to SPME coatings for the enrichment of SMs and OCPs.

  15. The effect of water presence on the photocatalytic oxidation of benzene, toluene, ethylbenzene and m-xylene in the gas-phase

    Science.gov (United States)

    Korologos, Christos A.; Philippopoulos, Constantine J.; Poulopoulos, Stavros G.

    2011-12-01

    In the present work, the gas-solid heterogeneous photocatalytic oxidation of benzene, toluene, ethylbenzene and m-xylene (BTEX) over UV-irradiated titanium dioxide was studied in an annular reactor operated in the CSTR (continuous stirred-tank reactor) mode. GC-FID and GC-MS were used for analysing reactor inlet and outlet streams. Initial BTEX concentrations were in the low parts per million (ppmv) range, whereas the water concentration was in the range of 0-35,230 ppmv and the residence time varied from 50 to 210 s. The effect of water addition on the photocatalytic process showed strong dependence on the type of the BTEX and the water vapour concentration. The increase in residence time resulted in a considerable increase in the conversion achieved for all compounds and experimental conditions. There was a clear interaction between residence time and water presence regarding the effect on conversions achieved. It was established that conversions over 95% could be achieved by adjusting appropriately the experimental conditions and especially the water concentration in the reactor. In all cases, no by-products were detected above the detection limit and carbon dioxide was the only compound detected. Finally, various Langmuir-Hinshelwood kinetic models have been tested in the analysis of the experimental data obtained. The kinetic data obtained confirmed that water had an active participation in the photocatalytic reactions of benzene, toluene, ethylbenzene and m-xylene since the model involving reaction of BTEX and water adsorbed on different active sites yielded the most successful fitting to the experimental results for the first three compounds, whereas the kinetic model based on the assumption that reaction between VOC and water dissociatively adsorbed on the photocatalyst takes place was the most appropriate in the case of m-xylene.

  16. 对、邻二甲苯和醋酸二元液体混合物在不同温度和压力下的密度和超额摩尔体积%Density and Excess Molar Volume of Binary Mixtures of p-Xylene+Acetic Acid and o-Xylene+Acetic Acid at Different Temperatures and Pressures

    Institute of Scientific and Technical Information of China (English)

    杨天宇; 夏淑倩; 邸志国; 马沛生

    2008-01-01

    A new apparatus was designed with a thick-walled glass capillary, electric heater tube with red copper and heat preservation. The thick-walled glass capillary was used for its advantages of resistance to acid corrosion and pressure, and ease of observation. The experimental densities over the entire range of mole fraction for the bi- nary mixture of p-xylene+acetic acid and o-xylene+acetic acid were measured using the new apparatus at tempera- tures ranging from 313.15K to 473.15K and pressure ranging from 0.20 to 2.0 MPa. The density values were used in the determination of excess molar volumes, VE. The Redlich-Kister equation was used to fit the excess molar volume values, and the coefficients and estimate of the standard error values were presented. The experimental re- suits prove that the density measurement apparatus is successful.

  17. Assessing microbial degradation of o-xylene at field-scale from the reduction in mass flow rate combined with compound-specific isotope analyses

    Science.gov (United States)

    Peter, A.; Steinbach, A.; Liedl, R.; Ptak, T.; Michaelis, W.; Teutsch, G.

    2004-07-01

    In recent years, natural attenuation (NA) has evolved into a possible remediation alternative, especially in the case of BTEX spills. In order to be approved by the regulators, biodegradation needs to be demonstrated which requires efficient site investigation and monitoring tools. Three methods—the Integral Groundwater Investigation method, the compound-specific isotope analysis (CSIA) and a newly developed combination of both—were used in this work to quantify at field scale the biodegradation of o-xylene at a former gasworks site which is heavily contaminated with BTEX and PAHs. First, the Integral Groundwater Investigation method [Schwarz, R., Ptak, T., Holder, T., Teutsch, G., 1998. Groundwater risk assessment at contaminated sites: a new investigation approach. In: Herbert, M. and Kovar, K. (Editors), GQ'98 Groundwater Quality: Remediation and Protection. IAHS Publication 250, pp. 68-71; COH 4 (2000) 170] was applied, which allows the determination of mass flow rates of o-xylene by integral pumping tests. Concentration time series obtained during pumping at two wells were used to calculate inversely contaminant mass flow rates at the two control planes that are defined by the diameter of the maximum isochrone. A reactive transport model was used within a Monte Carlo approach to identify biodegradation as the dominant process for reduction in the contaminant mass flow rate between the two consecutive control planes. Secondly, compound-specific carbon isotope analyses of o-xylene were performed on the basis of point-scale samples from the same two wells. The Rayleigh equation was used to quantify the degree of biodegradation that occurred between the wells. Thirdly, a combination of the Integral Groundwater Investigation method and the compound-specific isotope analysis was developed and applied. It comprises isotope measurements during the integral pumping tests and the evaluation of δ13C time series by an inversion algorithm to obtain spatially

  18. A study of the homogeneous stages in the catalytic oxidation of naphthalene, o-xylene, and benzene over a vibratory-fluidized catalyst bed

    Energy Technology Data Exchange (ETDEWEB)

    Korneichuk, G P; Stasevich, V P; Shaprinskaya, T M; Girushtin, G G; Gritsenko, V I; Zelenchukova, T G

    1978-01-01

    To identify the conditions for minimizing homogeneous states, the reaction kinetics were studied in a vibrating gradientless quartz reactor both in the presence and absence of the catalyst. A tenfold decrease of the reactional space in the absence of catalyst inhibited the oxidation (e.g., from a 68% conversion to 10% at 500/sup 0/C for o-xylene, and from 100% to 2% at 580/sup 0/C for benzene), whereas increasing the surface-volume ratio of the reactor increased the oxidation rate for benzene, which indicated that noncatalytic oxidation follows a radical-chain mechanism and involves both homogeneous (mainly) and heterogeneous stages. Catalytic oxidation carried out in a small volume (to avoid the homogeneous states) followed a heterogeneous mechanism up to 580/sup 0/C for naphthalene and o-xylene, and up to 550/sup 0/C for benzene. At higher temperatures, however, volume oxidation of benzene to carbon oxides was detected, which was favored by intense reactor vibration (i.e., increasing free space between catalyst grains), constituted 27% at 564/sup 0/C and 40% at 584/sup 0/C, and probably followed a heterogeneous-homogeneous mechanism. The partial oxidation products (i.e., phthalic and (for benzene) maleic anhydride) formed entirely by a heterogeneous mechanism. Tables and graphs.

  19. On the Diels-Alder approach to solely biomass-derived polyethylene terephthalate (PET): conversion of 2,5-dimethylfuran and acrolein into p-xylene.

    Science.gov (United States)

    Shiramizu, Mika; Toste, F Dean

    2011-10-24

    Polyethylene terephthalate (PET) is a polymeric material with high global demand. Conventionally, PET is produced from fossil-fuel-based materials. Herein, we explored the feasibility of a sustainable method for PET production by using solely bio-renewable resources. Specifically, 2,5-dimethylfuran (derived from lignocellulosic biomass through 5-(hydroxymethyl)furfural) and acrolein (produced from glycerol, a side product of biodiesel production) were converted into the key intermediate p-xylene (a precursor of terephthalic acid). This synthesis consists of a sequential Diels-Alder reaction, oxidation, dehydration, and decarboxylation. In particular, the pivotal first step, the Diels-Alder reaction, was studied in detail to provide useful kinetic and thermodynamic data. Although it was found that this reaction requires low temperature to proceed efficiently, which presents a limitation on economic feasibility on an industrial scale, the concept was realized and bio-derived p-xylene was obtained in 34% overall yield over four steps. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. The effect of gallium supported on mesoporous silica and its catalytic activity for oxidation of benzene, toluene and o-xylene

    Energy Technology Data Exchange (ETDEWEB)

    Schwanke, A.J.; Pergher, S.; Probst, L.F.D. [Universidade Federal do Rio Grande do Norte (UFRN), RN (Brazil); Balzer, R. [Universidade Federal do Parana (UFPR), PR (Brazil)

    2016-07-01

    Full text: Benzene, toluene and xylene (BTX) are a particular class of volatile organic compounds, which are highly toxic pollutants. In this study, samples of gallium-containing mesoporous silica (MS-Ga7% and MS-Ga11%) were synthesized and their catalytic activity in the oxidation of BTX was investigated. The physicochemical characterization by XRD, XPS, XRF, nitrogen adsorption and desorption isotherms at 77K, FTIR, SEM and TEM shows that the inclusion of gallium in the mesoporous silica structure leads to an increase in the number of oxygen vacancies in the structure of the MS-Ga system, which can result in an increase in the total and surface oxygen mobility. The results show the highest conversion for benzene (65%), with >40% for toluene and >28% for o-xylene. The high catalytic activity observed was attributed to a combination of several factors including a higher number of active sites (gallium and gallium oxide) being exposed, with a greater mobility of the active oxygen species on the surface of the catalyst promoting the catalytic activity. (author)

  1. Surface tension, density, and speed of sound for the ternary mixture {l_brace}diethyl carbonate + p-xylene + decane{r_brace}

    Energy Technology Data Exchange (ETDEWEB)

    Mosteiro, Laura; Casas, Lidia M. [Departamento de Fisica Aplicada, Facultad de Ciencias Experimentales, Universidad de Vigo, Lagoas Marcosende s/n, 36310 Vigo (Spain); Legido, Jose L. [Departamento de Fisica Aplicada, Facultad de Ciencias Experimentales, Universidad de Vigo, Lagoas Marcosende s/n, 36310 Vigo (Spain)], E-mail: xllegido@uvigo.es

    2009-05-15

    This paper reports the results of a new experimental study of thermophysical properties for the ternary mixture of {l_brace}diethyl carbonate + p-xylene + decane{r_brace}. Surface tension has been measured at 298.15 K and, density and speed of sound have been measured in the temperature range T = (288.15 to 308.15) K. Excess molar volumes, excess isentropic compressibilities, and surface tension deviations, have been calculated from experimental data. Surface tension deviations have been correlated with Cibulka equation and Nagata and Tamura equation was used for the other excess properties. Good accuracy has been obtained. These excess magnitudes are discussed qualitatively in terms of the nature and type of intermolecular interactions of the components involved.

  2. Modified dispersive liquid-liquid microextraction for pre-concentration of benzene, toluene, ethylbenzene and xylenes prior to their determination by GC

    International Nuclear Information System (INIS)

    Faraji, Hakim; Feizbakhsh, Alireza; Helalizadeh, Masoumeh

    2013-01-01

    We have developed a modified method for the extraction and preconcentration of benzene, toluene, ethylbenzene and xylenes (BTEX) in aqueous samples. It based on dispersive liquid-liquid microextraction along with solidification of floating organic microdrops. The dispersion of microvolumes of an extracting solvent into the aqueous occurs without dispersive solvent. Various parameters have been optimized. BTEX were quantified via GC with FID detection. Under optimized conditions, the preconcentration factors range from 301 to 514, extraction efficiencies from 60 to 103 %, repeatabilities from 2.2 to 4.1 %, and intermediate precisions from 3.5 to 7.0 %. The relative recovery for each analyte in water samples at three spiking levels is >85.6 %, with a relative standard deviation of <7.4 %. (author)

  3. Nitrogen regulation of the xyl genes of Pseudomonas putida mt-2 propagates into a significant effect of nitrate on m-xylene mineralization in soil

    DEFF Research Database (Denmark)

    Svenningsen, Nanna Bygvraa; Nicolaisen, Mette Haubjerg; Hansen, Hans Chr. Bruun

    2016-01-01

    nitrogen sensing status in both experimental systems. Hence, for nitrogen sources, regulatory patterns that emerge in soil reflect those observed in liquid cultures. The current study shows how distinct regulatory traits can lead to discrete environmental consequences; and it underpins that attempts......The nitrogen species available in the growth medium are key factors determining expression of xyl genes for biodegradation of aromatic compounds by Pseudomonas putida. Nitrogen compounds are frequently amended to promote degradation at polluted sites, but it remains unknown how regulation observed...... that NO3(-) compared with NH4(+) had a stimulating effect on xyl gene expression in pure culture as well as in soil, and that this stimulation was translated into increased m-xylene mineralization in soil. Furthermore, expression analysis of the nitrogen-regulated genes amtB and gdhA allowed us to monitor...

  4. Correct liquid scintillation counting of steroids and glycosides in RIA samples: a comparison of xylene-based, dioxane-based and colloidal counting systems. Chapter 14

    International Nuclear Information System (INIS)

    Spolders, H.

    1977-01-01

    In RIA, the following parameters are important for accurate liquid scintillation counting. (1) Absence of chemiluminescence. (2) Stability of count rate. (3) Dissolving properties for the sample. For samples with varying colours, a quench correction must be applied. For any type of accurate quench correction, a homogeneous sample is necessary. This can be obtained if proteins and the buffer can be dissolved completely in the scintillator solution. In this paper, these criteria are compared in xylene-based, dioxane-based and colloidal scintillation solutions for either bound or free antigens of different polarity. The labelling radioisotope used was 3 H. Using colloidal scintillators with plasma and buffer samples, phasing or sedimentation of salt or proteins sometimes occurs. The influence of sedimentation or phasing on count rate stability and correct quench correction is illustrated by varying the ratio between the scintillator solution and a RIA sample containing a semi-polar steroid aldosterone. (author)

  5. Synthesis of polyimides from α,αʹ-bis(3-aminophenoxy)-p-xylene: Spectroscopic, single crystal XRD and thermal studies

    Science.gov (United States)

    Ashraf, Ahmad Raza; Akhter, Zareen; Simon, Leonardo C.; McKee, Vickie; Castel, Charles Dal

    2018-05-01

    The meta-catenated ether-based diamine monomer α,αʹ-bis(3-aminophenoxy)-p-xylene (3APX) was synthesized from dinitro precursor α,αʹ-bis(3-nitrophenoxy)-p-xylene (3NPX). FTIR, 1H and 13C NMR spectroscopic studies accompanied by elemental analysis were performed for structural elucidations of 3NPX and 3APX. The spatial orientations of 3APX were explored by single crystal X-ray diffraction analysis. Its crystal system was found to be monoclinic, adopting the space group P21/c. The synthesized diamine monomer (3APX) was used for preparation of new series of polyimides by reacting with three different dianhydrides (BTDA, ODPA, 6FDA). The relevant copolyimides were developed via incorporation of 4,4ʹ-methylenedianiline (MDA) in the backbone of afore-synthesized polyimides. The structures of polyimides and copolyimides were verified by FTIR and 1H NMR spectroscopic techniques. Their properties were evaluated by dynamic and isothermal TGA (nitrogen and air atmospheres) and WAXRD studies. Polyimides displayed significantly high thermal stability as their degradation started around 400 °C and it was improved further by execution of copolymerization strategy with MDA. The 5% weight loss temperature (T5) of polyimides under nitrogen atmosphere was in the range of 425-460 °C while for copolyimides it increased to 454-498 °C. Thermal decomposition in air was slower than nitrogen between 400 and 550 °C however it was accelerated above 550 °C. Isothermal TGA disclosed that copolyimides have the ability to endure elevated temperatures for extended period. WAXRD analysis showed the amorphous nature of polyimides and copolyimides.

  6. The Crc global regulator inhibits the Pseudomonas putida pWW0 toluene/xylene assimilation pathway by repressing the translation of regulatory and structural genes.

    Science.gov (United States)

    Moreno, Renata; Fonseca, Pilar; Rojo, Fernando

    2010-08-06

    In Pseudomonas putida, the expression of the pWW0 plasmid genes for the toluene/xylene assimilation pathway (the TOL pathway) is subject to complex regulation in response to environmental and physiological signals. This includes strong inhibition via catabolite repression, elicited by the carbon sources that the cells prefer to hydrocarbons. The Crc protein, a global regulator that controls carbon flow in pseudomonads, has an important role in this inhibition. Crc is a translational repressor that regulates the TOL genes, but how it does this has remained unknown. This study reports that Crc binds to sites located at the translation initiation regions of the mRNAs coding for XylR and XylS, two specific transcription activators of the TOL genes. Unexpectedly, eight additional Crc binding sites were found overlapping the translation initiation sites of genes coding for several enzymes of the pathway, all encoded within two polycistronic mRNAs. Evidence is provided supporting the idea that these sites are functional. This implies that Crc can differentially modulate the expression of particular genes within polycistronic mRNAs. It is proposed that Crc controls TOL genes in two ways. First, Crc inhibits the translation of the XylR and XylS regulators, thereby reducing the transcription of all TOL pathway genes. Second, Crc inhibits the translation of specific structural genes of the pathway, acting mainly on proteins involved in the first steps of toluene assimilation. This ensures a rapid inhibitory response that reduces the expression of the toluene/xylene degradation proteins when preferred carbon sources become available.

  7. Efficacy of 1.5% Dish Washing Solution and 95% Lemon Water in Substituting Perilous Xylene as a Deparaffinizing Agent for Routine H and E Staining Procedure: A Short Study

    Directory of Open Access Journals (Sweden)

    Anuradha Ananthaneni

    2014-01-01

    Full Text Available Aim. To assess the efficacy of dish washing solution and diluted lemon water in deparaffinizing sections during conventional hematoxylin and eosin staining technique. Objective. The objective is to utilize eco-friendly economical substitute for xylene. Materials and Methods. Using twenty paraffin embedded tissue blocks, three sections each were prepared. One section was stained with conventional H and E method (Group A and the other two sections with xylene-free (XF H and E (Groups B and C. Staining characteristics were compared with xylene and scoring was given. Total score of 3–5 was regarded as adequate for diagnosis and less than that inadequate for diagnosis. Statistical Analysis. Chi-square test, Kruskal Wallis ANOVA test, and Mann-Whitney U test were used. Results. Adequacy of nuclear staining, crispness, and staining for diagnosis were greater in both Groups A and C (100% than Group B (95%. Adequacy of cytoplasmic staining was similar in all the three groups (100%. Group B showed comparatively superior uniform staining and less retention of wax. Conclusion. Dish washing solution or diluted lemon water can be replaced for xylene as deparaffinizing agent in hematoxylin and eosin procedure.

  8. Intermolecular Interactions in Binary Liquid Mixtures of Styrene with m-, o-, or p-xylene%苯乙烯与邻、间、对-二甲苯二元混合液的分子间相互作用

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The densities (ρ), ultrasonic speeds (v), and refractive indices (n) of binary mixtures of styrene (STY)with m-, o-, or p-xylene, including those of their pure liquids, were measured over the entire composition range at the temperatures 298.15, 303.15, 308.15, and 313.15 K. The excess volumes (VE), deviations in isentropic compressibilities(△ks), acoustic impedances (△Z), and refractive indices (△n) were calculated from the experimental data. Partial molar volumes (V0φ,2) and partial molar isentropic compressibilities (K0φ,2) of xylenes in styrene have also been calculated. The derived functions, namely, VE, △ks, △Z, △n, V0φ,2, and K0φ,2 were used to have a better understanding of the intermolecular interactions occurring between the component molecules of the present liquid mixtures. The variations of these parameters suggest that the interactions between styrene and o-, m-, or p-xylene molecules follow the sequences: p-xylene>o-xylene>m-xylene. Apart from using density data for the calculation of VE, excess molar volumes were also estimated using refractive index data. Furthermore, several refractive index mixing rules have been used to estimate the refractive indices of the studied liquid mixtures theoretically. Overall, the computed and measured data were interpreted in terms of interactions between the mixing components.

  9. Evaluation of the adsorption capacity of nano-graphene and nano-graphene oxide for xylene removal from air and their comparison with the standard adsorbent of activated carbon to introduce the optimized one

    Directory of Open Access Journals (Sweden)

    Akram Tabrizi

    2016-06-01

    Full Text Available Introduction: Volatile organic compounds from industrial activities are one of the most important pollutants released into the air and have adverse effects on human and environment. Therefore, they should be removed before releasing into atmosphere. The aim of the study was to evaluate xylene removal from air by nano-grapheme and nano-graphene oxide in comparison with activated carbon adsorbent. Material and Method:  After preparing adsorbents of activated carbon, nano-graphene, and nano-graphene oxide, experiments adsorption capacity in static mode (Batch were carried out in a glass vial. Some variables including contact time, the amount of adsorbent, the concentration of xylene, and the temperature were studied. Langmuir absorption isotherms were used in order to study the adsorption capacity of xylene on adsorbents. Moreover, sample analysis was done by gas chromatography with Flame Ionization Detector (GC-FID. Results: The adsorption capacities of activated carbon, nano-graphene oxide and nano-graphene for removal of xylene were obtained 349.8, 14.5, and 490 mg/g, respectively. The results of Scanning Electron Microscope (SEM for nano-graphene and nano-graphene oxide showed particle size of less than 100 nm. While, the results of Transmission Electron Microscope (TEM showed particle size of 45nm for nano-graphene and 65 nm for nano-graphene oxide. Also, X-Ray Diffraction (XRD showed cube structure of nano-adsorbents. Conclusion: In constant humidity, increase in exposure time and temperature caused an increase in the adsorption capacity. The results revealed greater adsorption capacity of xylene removal for nano-graphene compared to the activated carbon, and nano-graphene oxide.

  10. Additive mixture effects of estrogenic chemicals in human cell-based assays can be influenced by inclusion of chemicals with differing effect profiles.

    Directory of Open Access Journals (Sweden)

    Richard Mark Evans

    Full Text Available A growing body of experimental evidence indicates that the in vitro effects of mixtures of estrogenic chemicals can be well predicted from the estrogenicity of their components by the concentration addition (CA concept. However, some studies have observed small deviations from CA. Factors affecting the presence or observation of deviations could include: the type of chemical tested; number of mixture components; mixture design; and assay choice. We designed mixture experiments that address these factors, using mixtures with high numbers of components, chemicals from diverse chemical groups, assays with different in vitro endpoints and different mixture designs and ratios. Firstly, the effects of mixtures composed of up to 17 estrogenic chemicals were examined using estrogenicity assays with reporter-gene (ERLUX and cell proliferation (ESCREEN endpoints. Two mixture designs were used: 1 a 'balanced' design with components present in proportion to a common effect concentration (e.g. an EC(10 and 2 a 'non-balanced' design with components in proportion to potential human tissue concentrations. Secondly, the individual and simultaneous ability of 16 potential modulator chemicals (each with minimal estrogenicity to influence the assay outcome produced by a reference mixture of estrogenic chemicals was examined. Test chemicals included plasticizers, phthalates, metals, PCBs, phytoestrogens, PAHs, heterocyclic amines, antioxidants, UV filters, musks, PBDEs and parabens. In all the scenarios tested, the CA concept provided a good prediction of mixture effects. Modulation studies revealed that chemicals possessing minimal estrogenicity themselves could reduce (negatively modulate the effect of a mixture of estrogenic chemicals. Whether the type of modulation we observed occurs in practice most likely depends on the chemical concentrations involved, and better information is required on likely human tissue concentrations of estrogens and of potential

  11. Additive mixture effects of estrogenic chemicals in human cell-based assays can be influenced by inclusion of chemicals with differing effect profiles.

    Science.gov (United States)

    Evans, Richard Mark; Scholze, Martin; Kortenkamp, Andreas

    2012-01-01

    A growing body of experimental evidence indicates that the in vitro effects of mixtures of estrogenic chemicals can be well predicted from the estrogenicity of their components by the concentration addition (CA) concept. However, some studies have observed small deviations from CA. Factors affecting the presence or observation of deviations could include: the type of chemical tested; number of mixture components; mixture design; and assay choice. We designed mixture experiments that address these factors, using mixtures with high numbers of components, chemicals from diverse chemical groups, assays with different in vitro endpoints and different mixture designs and ratios. Firstly, the effects of mixtures composed of up to 17 estrogenic chemicals were examined using estrogenicity assays with reporter-gene (ERLUX) and cell proliferation (ESCREEN) endpoints. Two mixture designs were used: 1) a 'balanced' design with components present in proportion to a common effect concentration (e.g. an EC(10)) and 2) a 'non-balanced' design with components in proportion to potential human tissue concentrations. Secondly, the individual and simultaneous ability of 16 potential modulator chemicals (each with minimal estrogenicity) to influence the assay outcome produced by a reference mixture of estrogenic chemicals was examined. Test chemicals included plasticizers, phthalates, metals, PCBs, phytoestrogens, PAHs, heterocyclic amines, antioxidants, UV filters, musks, PBDEs and parabens. In all the scenarios tested, the CA concept provided a good prediction of mixture effects. Modulation studies revealed that chemicals possessing minimal estrogenicity themselves could reduce (negatively modulate) the effect of a mixture of estrogenic chemicals. Whether the type of modulation we observed occurs in practice most likely depends on the chemical concentrations involved, and better information is required on likely human tissue concentrations of estrogens and of potential modulators

  12. [Exposure to hazardous chemical substances in furniture industry].

    Science.gov (United States)

    Pośniak, Małgorzata; Kowalska, Joanna; Makhniashvili, Ivan

    2005-01-01

    The aim of the study was to assess the exposure to organic solvents in plants of the furniture industry. Studies were conducted in five furniture plants. Hazardous chemicals present in the air at workposts were determined by capillary gas chromatography with mass spectrometry and flame ionization detection. The analysis of air samples collected at the workposts allowed to identify the following chemicals occurring during varnishing and cleaning of furniture surface elements: acetone, butan-2-one, ethyl, isobutyl and methoxypropyl acetate, 4-methylpentan-2-on, toluene, ethylbenzene and xylenes. Indices characteristic of combined exposure ranged from 0.13 to 1.67 and exceeded the limit value at 21% of workposts. The results of the study indicate that chemicals present at representative workposts during the furniture production are harmful to health of workers, especially those involved in varnishing and cleaning of furniture elements.

  13. Variations of some parameters of enzyme induction in chemical workers

    Energy Technology Data Exchange (ETDEWEB)

    Dolara, P. (Univ. of Florence, Italy); Lodovici, M.; Buffoni, F.; Buiatti, E.; Baccetti, S.; Ciofini, O.; Bavazzano, P.; Barchielli, S.; Vannucci, V.

    1982-01-01

    Several parameters related to mono-oxygenase activity were followed in a population of chemical workers and controls. Workers exposed to toluene and xylene had a significant increase of urinary glucaric acid, that was correlated with hippuric acid excretion. On the other hand, workers exposed to pigments showed a marked increase of antipyrine half-life. A dose-related decrease of liver N-demethylase was induced in rats by the administration of a mixture of three of the pigments in use in the plant. Serum gamma-glutamyltranspeptidase was decreased in the workers exposed to pigments, but this variation was not statistically significant. The exposure to different chemicals in the workplace seemed to induce a complicated variation of mono-oxygenase levels, some enzyme being inhibited and others induced in the same group of workers. The sensitivity of these workers to toxic effects of chemicals, carcinogenic compounds and drugs seems to differ markedly from the control population.

  14. Chemical Peels

    Science.gov (United States)

    ... care Kids’ zone Video library Find a dermatologist Chemical peels Overview Chemical peels: Overview Also called chemexfoliation , derma peeling Do ... Overview Chemical peels: FAQs Chemical peels: Preparation FAQs Chemical peels: FAQs To help you decide whether this ...

  15. Radiochemical studies in chemical separation and spectrographic determination of rare earths in thorium oxide matrix (Preprint No. RA.06)

    International Nuclear Information System (INIS)

    Adya, V.C.; Dhawale, B.A.; Rajeshwari, B.; Bangia, T.R.; Sastry, M.D.

    1989-01-01

    A chemical separation procedure was standardised for the separation of traces of rare earths from ThO 2 matrix using HDEHP (Di 2-ethyl hexyl phosphoric acid). The studies were carried out using both nitric acid and hydrochloric acid medium in different concentrations. The extraction studies were also carried out using radioactive isotopes of rare earths viz. 141 Ce, 152-154 Eu, 153 Gd, 170 Tm etc. The extraction was effective in both media. In 0.1 M HDEHP/xylene and 3 M HNO 3 , Ce was partially extracted into organic phase. So HCl/xylene medium was chosen for extraction purposes. The recovery was confirmed by both gamma counting and emission spectropgraphic method. It was found to be quantitative within experimental error. The separation procedure development here was used for determination of rare earths in thorium oxide matrix by emission spectrographic method. (author)

  16. Chemical contamination assessment in mangrove-lined Caribbean coastal systems using the oyster Crassostrea rhizophorae as biomonitor species.

    Science.gov (United States)

    Aguirre-Rubí, Javier R; Luna-Acosta, Andrea; Etxebarría, Nestor; Soto, Manu; Espinoza, Félix; Ahrens, Michael J; Marigómez, Ionan

    2018-05-01

    This paper aims to contribute to the use of mangrove cupped oyster, Crassostrea rhizophorae, as a biomonitor species for chemical contamination assessment in mangrove-lined Caribbean coastal systems. Sampling was carried out in eight localities (three in Nicaragua and five in Colombia) with different types and levels of contamination. Oysters were collected during the rainy and dry seasons of 2012-2013 and the tissue concentrations of metals, polycyclic aromatic hydrocarbons (PAHs), and persistent organic pollutants (POPs) were determined. Low tissue concentrations of metals (except Hg) and PAHs; moderate-to-high tissue concentrations of Hg, hexachlorocyclohexanes (HCHs), and dichlorodiphenyl-trichloroethanes (DDTs); detectable levels of chlorpyrifos, polychlorinated biphenyls (PCBs) (mainly CB28, CB118, CB138 and CB 153) and brominated diphenyl ethers 85 (BDE85); and negligible levels of musks were recorded in Nicaraguan oysters. A distinct profile of POPs was identified in Colombia, where the tissue concentrations of PCBs and synthetic musk fragrances were low to moderate, and Ag, As, Cd, Pb, and PAHs ranged from moderate to extremely high. Overall, the values recorded for HCHs, DDTs and PCBs in Nicaraguan mangrove cupped oysters greatly exceeded the reference values in tissues of C. rhizophorae from the Wider Caribbean Region, whereas only the levels of PCBs were occasionally surpassed in Colombia. Different contaminant profiles were distinguished between oysters from Nicaragua and Colombia in radar plots constructed using the main groups of contaminants (metals, PAHs, musks, PCBs, and organochlorine pesticides (OCPs)). Likewise, integrated pollution indices revealed differences in the levels of contaminants. Moreover, the profiles and levels in oyster tissues also varied with season. Thus, principal component analysis clearly discriminated Nicaraguan and Colombian localities and, especially in Colombia, seasonal trends in chemical contamination and differences

  17. Characterization of the pharmacokinetics of gasoline using PBPK modeling with a complex mixtures chemical lumping approach.

    Science.gov (United States)

    Dennison, James E; Andersen, Melvin E; Yang, Raymond S H

    2003-09-01

    Gasoline consists of a few toxicologically significant components and a large number of other hydrocarbons in a complex mixture. By using an integrated, physiologically based pharmacokinetic (PBPK) modeling and lumping approach, we have developed a method for characterizing the pharmacokinetics (PKs) of gasoline in rats. The PBPK model tracks selected target components (benzene, toluene, ethylbenzene, o-xylene [BTEX], and n-hexane) and a lumped chemical group representing all nontarget components, with competitive metabolic inhibition between all target compounds and the lumped chemical. PK data was acquired by performing gas uptake PK studies with male F344 rats in a closed chamber. Chamber air samples were analyzed every 10-20 min by gas chromatography/flame ionization detection and all nontarget chemicals were co-integrated. A four-compartment PBPK model with metabolic interactions was constructed using the BTEX, n-hexane, and lumped chemical data. Target chemical kinetic parameters were refined by studies with either the single chemical alone or with all five chemicals together. o-Xylene, at high concentrations, decreased alveolar ventilation, consistent with respiratory irritation. A six-chemical interaction model with the lumped chemical group was used to estimate lumped chemical partitioning and metabolic parameters for a winter blend of gasoline with methyl t-butyl ether and a summer blend without any oxygenate. Computer simulation results from this model matched well with experimental data from single chemical, five-chemical mixture, and the two blends of gasoline. The PBPK model analysis indicated that metabolism of individual components was inhibited up to 27% during the 6-h gas uptake experiments of gasoline exposures.

  18. Development of California Public Health Goals (PHGs) for chemicals in drinking water.

    Science.gov (United States)

    Howd, R A; Brown, J P; Morry, D W; Wang, Y Y; Bankowska, J; Budroe, J D; Campbell, M; DiBartolomeis, M J; Faust, J; Jowa, L; Lewis, D; Parker, T; Polakoff, J; Rice, D W; Salmon, A G; Tomar, R S; Fan, A M

    2000-01-01

    As part of a program for evaluation of environmental contaminants in drinking water, risk assessments are being conducted to develop Public Health Goals (PHGs) for chemicals in drinking water, based solely on public health considerations. California's Safe Drinking Water Act of 1996 mandated the development of PHGs for over 80 chemicals by 31 December 1999. The law allowed these levels to be set higher or lower than federal maximum contaminant levels (MCLs), including a level of zero if data are insufficient to determine a specific level. The estimated safe levels and toxicological rationale for the first 26 of these chemicals are described here. The chemicals include alachlor, antimony, benzo[a]pyrene, chlordane, copper, cyanide, dalapon, 1,2-dichlorobenzene, 1,4-dichlorobenzene, 2,4-D, diethylhexylphthalate, dinoseb, endothall, ethylbenzene, fluoride, glyphosate, lead, nitrate, nitrite, oxamyl, pentachlorophenol, picloram, trichlorofluoromethane, trichlorotrifluoroethane, uranium and xylene(s). These risk assessments are to be considered by the State of California in revising and developing state MCLs for chemicals in drinking water (which must not exceed federal MCLs). The estimates are also notable for incorporation or consideration of newer guidelines and principles for risk assessment extrapolations.

  19. Testicular atrophy and loss of nerve growth factor-immunoreactive germ cell line in rats exposed to n-hexane and a protective effect of simultaneous exposure to toluene or xylene

    Energy Technology Data Exchange (ETDEWEB)

    Nylen, P; Johnson, A C; Hoeglund, G; Ebendal, T; Eriksdotter-Nilsson, M; Henschen, A; Olson, L; Hansson, T; Kronevi, T; Kvist, U

    1989-07-01

    Testicular and germ cell line morphology in rats were studied 2 weeks, 10 months and 14 months after cessation of a 61-day inhalation exposure to 1000 ppm n-hexane. Androgen biosynthetic capacity of testis, testosterone blood concentration, vas deferens morphology and noradrenaline (NA) concentration, epididymal sperm morphology, and fertility were also studied. Severe testicular atrophy involving the seminiferous tubules with loss of the nerve growth factor (NGF) immunoreactive germ cell line was found. Total loss of the germ cell line was found in a fraction of animals up to 14 months post-exposure, indicating permanent testicular damage. No impairment of androgen synthesis or androgen dependent accessory organs was observed. Simultaneous administration of 1000 ppm n-hexane and 1000 ppm toluene, or 1000 ppm n-hexane and 1000 ppm xylene, did not cause germ cell line alterations or testicular atrophy. Toluene and xylene were thus found to protect from n-hexane induced testicular atrophy. (orig.).

  20. Optimization of the p-xylene oxidation process by a multi-objective differential evolution algorithm with adaptive parameters co-derived with the population-based incremental learning algorithm

    Science.gov (United States)

    Guo, Zhan; Yan, Xuefeng

    2018-04-01

    Different operating conditions of p-xylene oxidation have different influences on the product, purified terephthalic acid. It is necessary to obtain the optimal combination of reaction conditions to ensure the quality of the products, cut down on consumption and increase revenues. A multi-objective differential evolution (MODE) algorithm co-evolved with the population-based incremental learning (PBIL) algorithm, called PBMODE, is proposed. The PBMODE algorithm was designed as a co-evolutionary system. Each individual has its own parameter individual, which is co-evolved by PBIL. PBIL uses statistical analysis to build a model based on the corresponding symbiotic individuals of the superior original individuals during the main evolutionary process. The results of simulations and statistical analysis indicate that the overall performance of the PBMODE algorithm is better than that of the compared algorithms and it can be used to optimize the operating conditions of the p-xylene oxidation process effectively and efficiently.

  1. Optimization of non-thermal plasma efficiency in the simultaneous elimination of benzene, toluene, ethyl-benzene, and xylene from polluted airstreams using response surface methodology.

    Science.gov (United States)

    Najafpoor, Ali Asghar; Jonidi Jafari, Ahmad; Hosseinzadeh, Ahmad; Khani Jazani, Reza; Bargozin, Hasan

    2018-01-01

    Treatment with a non-thermal plasma (NTP) is a new and effective technology applied recently for conversion of gases for air pollution control. This research was initiated to optimize the efficient application of the NTP process in benzene, toluene, ethyl-benzene, and xylene (BTEX) removal. The effects of four variables including temperature, initial BTEX concentration, voltage, and flow rate on the BTEX elimination efficiency were investigated using response surface methodology (RSM). The constructed model was evaluated by analysis of variance (ANOVA). The model goodness-of-fit and statistical significance was assessed using determination coefficients (R 2 and R 2 adj ) and the F-test. The results revealed that the R 2 proportion was greater than 0.96 for BTEX removal efficiency. The statistical analysis demonstrated that the BTEX removal efficiency was significantly correlated with the temperature, BTEX concentration, voltage, and flow rate. Voltage was the most influential variable affecting the dependent variable as it exerted a significant effect (p < 0.0001) on the response variable. According to the achieved results, NTP can be applied as a progressive, cost-effective, and practical process for treatment of airstreams polluted with BTEX in conditions of low residence time and high concentrations of pollutants.

  2. Effects of plasma polymerized para-xylene intermediate layers on characteristics of flexible organic light emitting diodes fabricated on polyethylene terephthalate substrates

    International Nuclear Information System (INIS)

    Sohn, Sunyoung; Kim, Kyuhyung; Kho, Samil; Jung, Donggeun; Boo, Jin-hyo

    2008-01-01

    Characteristics of flexible organic light emitting diodes (FOLEDs) with the plasma polymerized para-xylene (PPpX) intermediate layer were investigated. For the purpose of reducing moisture permeation through plastic substrates, a PPpX intermediate layer was inserted between FOLEDs and the plastic substrates. As the concentration of C-H bonding in the PPpX film deposited at 25 deg. C was increased, PPpX films showed increased transmittance. Surface morphologies of polyethylene terephthalate (PET) covered with the PPpX intermediate layer were improved compared to PET without PPpX on it. Due to the highly cross-linked network structure in the plasma polymer film, water vapor permeability of PET substrates with the PPpX intermediate layer of 75 nm was decreased compared to PET substrates without PPpX on it. FOLEDs with the PPpX intermediate layer showed improved optical and electrical characteristics as well as lifetimes than FOLEDs without the PPpX intermediate layer

  3. Biodegradation of BTEX (Benzene, Toluene, Ethylbenzene and Xylenes) composites present in the petrochemical effluents industries; Biodegradacao dos compostos BTX (Benzeno, Tolueno e Xilenos) presentes em efluentes petroquimicos

    Energy Technology Data Exchange (ETDEWEB)

    Minatti, Gheise; Mello, Josiane M.M. de; Souza, Selene M.A. Guelli Ulson de; Ulson de, Antonio Augusto [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil)

    2008-07-01

    The compounds BTX inside of the petrochemical effluent have presented a high potential of pollution, representing a serious risk to the environment and to the human. The great improvements in the field of biological treatment of liquid effluent were reached through the process using biofilm capable of degrading toxic compounds. The objective of this paper is to determine the degradation kinetics of BTX using biofilm. The experimental data were compared with two kinetic models, kinetic of first order and model of Michaelis-Menten. The kinetic parameters of BTX compounds were experimentally obtained in a bioreactor in batch with biomass immobilized in activated-carbon, being fed daily with solution of nutrients and BTX. For the kinetic models studied in this paper, the best performance was achieved with the model of Michaelis-Menten showing a good correlation coefficient for the three compounds. The biomass amount in these bioreactors was 49.18, 28.35 and 5.15 mg of SSV per gram of support for the toluene, benzene and o-xylene, respectively. The experimental tests showed that the biomass inside of bioreactor is capable to degrade all compounds in a time of approximately 300 minutes. (author)

  4. Treatment of waste gas from the breather vent of a vertical fixed roof p-xylene storage tank by a trickle-bed air biofilter.

    Science.gov (United States)

    Chang, Shenteng; Lu, Chungsying; Hsu, Shihchieh; Lai, How-Tsan; Shang, Wen-Lin; Chuang, Yeong-Song; Cho, Chi-Huang; Chen, Sheng-Han

    2011-01-01

    This study applied a pilot-scale trickle-bed air biofilter (TBAB) system for treating waste gas emitted from the breather vent of a vertical fixed roof storage tank containing p-xylene (p-X) liquid. The volatile organic compound (VOC) concentration of the waste gas was related to ambient temperature as well as solar radiation, peaking at above 6300 ppmv of p-X and 25000 ppmv of total hydrocarbons during the hours of 8 AM to 3 PM. When the activated carbon adsorber was employed as a VOC buffer, the peak waste gas VOC concentration was significantly reduced resulting in a stably and efficiently performing TBAB system. The pressure drop appeared to be low, reflecting that the TBAB system could be employed in the prolonged operation with a low running penalty. These advantages suggest that the TBAB system is a cost-effective treatment technology for VOC emission from a fixed roof storage tank. Copyright © 2010 Elsevier Ltd. All rights reserved.

  5. Molecular Symmetry Analysis of Low-Energy Torsional and Vibrational States in the S_{0} and S_{1} States of p-XYLENE to Interpret the Rempi Spectrum

    Science.gov (United States)

    Groner, Peter; Gardner, Adrian M.; Tuttle, William Duncan; Wright, Timothy G.

    2017-06-01

    The electronic transition S_{1} ← S_{0} of p-xylene (pXyl) has been observed by REMPI spectroscopy. Its analysis required a detailed investigation of the molecular symmetry of pXyl whose methyl groups are almost free internal rotors. The molecular symmetry group of pXyl has 72 operators. This group, called [33]D_{2h}, is isomorphic to G_{36}(EM), the double group for ethane and dimethyl acetylene even though it is NOT a double group for pXyl. Loosely speaking, the group symbol, [33]D_{2h}, indicates that is for a molecule with two threefold rotors on a molecular frame with D_{2h} point group symmetry. The transformation properties of the (i) free internal rotor basis functions for the torsional coordinates, (ii) the asymmetric rotor (Wang) basis functions for the Eulerian angles, (iii) nuclear spin functions, (iv) potential function, and (v) transitions dipole moment functions were determined. The forms of the torsional potential in the S_{0} and S_{1} states and the dependence of the first order torsional splittings on the potential coefficients have been obtained. AM Gardner, WD Tuttle, P. Groner, TG Wright, J. Chem. Phys., submitted Dec 2016 P Groner, JR Durig, J. Chem. Phys., 66 (1977) 1856 PR Bunker, P Jensen, Molecular Symmetry and Spectroscopy (1998, NRC Research Press, Ottawa, 2nd ed.)

  6. Organic chemicals in the environment

    International Nuclear Information System (INIS)

    Anderson, T.A.; Beauchamp, J.J.; Walton, B.T.

    1991-01-01

    Disappearance of 15 volatile and semivolatile organic compounds was determined in a mixture added to two different soil types using experimental procedures to distinguish abiotic losses from biological degradation over a 7-d period. Losses due to volatilization were quantified and mass balances were calculated for each compound. The compounds (methyl ethyl ketone; tetrahydrofuran; chlorobenzene; benzene; chloroform; carbon tetrachloride; p-xylene; 1,2-dichlorobenzene; cis-1,4-dich-loro-2-butene; 1,2,3-trichloropropane; 2-chloronaphthalene; ethylene dibromide; hexachlorobenzene; nitrobenzene; and toluene) were applied to the soil in a mixture such that the concentration of each chemical was 100 mg/kg soil (dry wt.). Apparent half-lives for the 15 organic compounds ranged from 14 C-toluene, were unsuccessful. Nonreversible sorption and preanalysis storage conditions were considered as contributors to this inability to achieve a mass balance. On the basis of these results, the authors strongly advise positive accounting for all test compounds and degradation products at the conclusion of studies involving volatile and semivolatile compounds

  7. Chemical Emergencies

    Science.gov (United States)

    When a hazardous chemical has been released, it may harm people's health. Chemical releases can be unintentional, as in the case of an ... the case of a terrorist attack with a chemical weapon. Some hazardous chemicals have been developed by ...

  8. Quantification of benzene, toluene, ethylbenzene and o-xylene in internal combustion engine exhaust with time-weighted average solid phase microextraction and gas chromatography mass spectrometry.

    Science.gov (United States)

    Baimatova, Nassiba; Koziel, Jacek A; Kenessov, Bulat

    2015-05-11

    A new and simple method for benzene, toluene, ethylbenzene and o-xylene (BTEX) quantification in vehicle exhaust was developed based on diffusion-controlled extraction onto a retracted solid-phase microextraction (SPME) fiber coating. The rationale was to develop a method based on existing and proven SPME technology that is feasible for field adaptation in developing countries. Passive sampling with SPME fiber retracted into the needle extracted nearly two orders of magnitude less mass (n) compared with exposed fiber (outside of needle) and sampling was in a time weighted-averaging (TWA) mode. Both the sampling time (t) and fiber retraction depth (Z) were adjusted to quantify a wider range of Cgas. Extraction and quantification is conducted in a non-equilibrium mode. Effects of Cgas, t, Z and T were tested. In addition, contribution of n extracted by metallic surfaces of needle assembly without SPME coating was studied. Effects of sample storage time on n loss was studied. Retracted TWA-SPME extractions followed the theoretical model. Extracted n of BTEX was proportional to Cgas, t, Dg, T and inversely proportional to Z. Method detection limits were 1.8, 2.7, 2.1 and 5.2 mg m(-3) (0.51, 0.83, 0.66 and 1.62 ppm) for BTEX, respectively. The contribution of extraction onto metallic surfaces was reproducible and influenced by Cgas and t and less so by T and by the Z. The new method was applied to measure BTEX in the exhaust gas of a Ford Crown Victoria 1995 and compared with a whole gas and direct injection method. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Identification of the sexually dimorphic gastrin-releasing peptide system in the lumbosacral spinal cord that controls male reproductive function in the mouse and Asian house musk shrew (Suncus murinus).

    Science.gov (United States)

    Tamura, Kei; Kobayashi, Yasuhisa; Hirooka, Asuka; Takanami, Keiko; Oti, Takumi; Jogahara, Takamichi; Oda, Sen-Ichi; Sakamoto, Tatsuya; Sakamoto, Hirotaka

    2017-05-01

    Several regions of the brain and spinal cord control male reproductive function. We previously demonstrated that the gastrin-releasing peptide (GRP) system, located in the lumbosacral spinal cord of rats, controls spinal centers to promote penile reflexes during male copulatory behavior. However, little information exists on the male-specific spinal GRP system in animals other than rats. The objective of this study was to examine the functional generality of the spinal GRP system in mammals using the Asian house musk shrew (Suncus murinus; suncus named as the laboratory strain), a specialized placental mammal model. Mice are also used for a representative model of small laboratory animals. We first isolated complementary DNA encoding GRP in suncus. Phylogenetic analysis revealed that suncus preproGRP was clustered to an independent branch. Reverse transcription-PCR showed that GRP and its receptor mRNAs were both expressed in the lumbar spinal cord of suncus and mice. Immunohistochemistry for GRP demonstrated that the sexually dimorphic GRP system and male-specific expression/distribution patterns of GRP in the lumbosacral spinal cord in suncus are similar to those of mice. In suncus, we further found that most GRP-expressing neurons in males also express androgen receptors, suggesting that this male-dominant system in suncus is also androgen-dependent. Taken together, these results indicate that the sexually dimorphic spinal GRP system exists not only in mice but also in suncus, suggesting that this system is a conserved property in mammals. J. Comp. Neurol. 525:1586-1598, 2017. © 2016 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  10. Semivolatile organic compounds in residential air along the Arizona - Mexico border

    Science.gov (United States)

    Gale, R.W.; Cranor, W.L.; Alvarez, D.A.; Huckins, J.N.; Petty, J.D.; Robertson, G.L.

    2009-01-01

    Concerns about indoor air quality and the potential effects on people living in these environments are increasing as more reports about the toxicities and the potential indoor air exposure levels of household-use chemicals and chemicals fromhousingandfurnishingmanufactureinairarebeingassessed. Gas chromatography/mass spectrometry was used to confirm numerous airborne contaminants obtained from the analysis of semipermeable membrane devices deployed inside of 52 homes situated along the border between Arizona and Mexico. We also describe nontarget analytes in the organochlorine pesticide fractions of 12 of these homes; this fraction is also the most likelytocontainthebroadestscopeofbioconcentratablechemicals accumulated from the indoor air. Approximately 400 individual components were identified, ranging from pesticides to a wide array of hydrocarbons, fragrances such as the musk xylenes, flavors relating to spices, aldehydes, alcohols, esters and phthalate esters, and other miscellaneous types of chemicals. The results presented in this study demonstrate unequivocally that the mixture of airborne chemicals present indoors is far more complex than previously demonstrated. ?? 2009 American Chemical Society.

  11. Humidity independent mass spectrometry for gas phase chemical analysis via ambient proton transfer reaction.

    Science.gov (United States)

    Zhu, Hongying; Huang, Guangming

    2015-03-31

    In this work, a humidity independent mass spectrometric method was developed for rapid analysis of gas phase chemicals. This method is based upon ambient proton transfer reaction between gas phase chemicals and charged water droplets, in a reaction chamber with nearly saturate humidity under atmospheric pressure. The humidity independent nature enables direct and rapid analysis of raw gas phase samples, avoiding time- and sample-consuming sample pretreatments in conventional mass spectrometry methods to control sample humidity. Acetone, benzene, toluene, ethylbenzene and meta-xylene were used to evaluate the analytical performance of present method. The limits of detection for benzene, toluene, ethylbenzene and meta-xylene are in the range of ∼0.1 to ∼0.3 ppbV; that of benzene is well below the present European Union permissible exposure limit for benzene vapor (5 μg m(-3), ∼1.44 ppbV), with linear ranges of approximately two orders of magnitude. The majority of the homemade device contains a stainless steel tube as reaction chamber and an ultrasonic humidifier as the source of charged water droplets, which makes this cheap device easy to assemble and facile to operate. In addition, potential application of this method was illustrated by the real time identification of raw gas phase chemicals released from plants at different physiological stages. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Spatial variability in levels of benzene, formaldehyde, and total benzene, toluene, ethylbenzene and xylenes in New York City: a land-use regression study

    Directory of Open Access Journals (Sweden)

    Kheirbek Iyad

    2012-07-01

    Full Text Available Abstract Background Hazardous air pollutant exposures are common in urban areas contributing to increased risk of cancer and other adverse health outcomes. While recent analyses indicate that New York City residents experience significantly higher cancer risks attributable to hazardous air pollutant exposures than the United States as a whole, limited data exist to assess intra-urban variability in air toxics exposures. Methods To assess intra-urban spatial variability in exposures to common hazardous air pollutants, street-level air sampling for volatile organic compounds and aldehydes was conducted at 70 sites throughout New York City during the spring of 2011. Land-use regression models were developed using a subset of 59 sites and validated against the remaining 11 sites to describe the relationship between concentrations of benzene, total BTEX (benzene, toluene, ethylbenzene, xylenes and formaldehyde to indicators of local sources, adjusting for temporal variation. Results Total BTEX levels exhibited the most spatial variability, followed by benzene and formaldehyde (coefficient of variation of temporally adjusted measurements of 0.57, 0.35, 0.22, respectively. Total roadway length within 100 m, traffic signal density within 400 m of monitoring sites, and an indicator of temporal variation explained 65% of the total variability in benzene while 70% of the total variability in BTEX was accounted for by traffic signal density within 450 m, density of permitted solvent-use industries within 500 m, and an indicator of temporal variation. Measures of temporal variation, traffic signal density within 400 m, road length within 100 m, and interior building area within 100 m (indicator of heating fuel combustion predicted 83% of the total variability of formaldehyde. The models built with the modeling subset were found to predict concentrations well, predicting 62% to 68% of monitored values at validation sites. Conclusions Traffic and

  13. Spatial variability in levels of benzene, formaldehyde, and total benzene, toluene, ethylbenzene and xylenes in New York City: a land-use regression study.

    Science.gov (United States)

    Kheirbek, Iyad; Johnson, Sarah; Ross, Zev; Pezeshki, Grant; Ito, Kazuhiko; Eisl, Holger; Matte, Thomas

    2012-07-31

    Hazardous air pollutant exposures are common in urban areas contributing to increased risk of cancer and other adverse health outcomes. While recent analyses indicate that New York City residents experience significantly higher cancer risks attributable to hazardous air pollutant exposures than the United States as a whole, limited data exist to assess intra-urban variability in air toxics exposures. To assess intra-urban spatial variability in exposures to common hazardous air pollutants, street-level air sampling for volatile organic compounds and aldehydes was conducted at 70 sites throughout New York City during the spring of 2011. Land-use regression models were developed using a subset of 59 sites and validated against the remaining 11 sites to describe the relationship between concentrations of benzene, total BTEX (benzene, toluene, ethylbenzene, xylenes) and formaldehyde to indicators of local sources, adjusting for temporal variation. Total BTEX levels exhibited the most spatial variability, followed by benzene and formaldehyde (coefficient of variation of temporally adjusted measurements of 0.57, 0.35, 0.22, respectively). Total roadway length within 100 m, traffic signal density within 400 m of monitoring sites, and an indicator of temporal variation explained 65% of the total variability in benzene while 70% of the total variability in BTEX was accounted for by traffic signal density within 450 m, density of permitted solvent-use industries within 500 m, and an indicator of temporal variation. Measures of temporal variation, traffic signal density within 400 m, road length within 100 m, and interior building area within 100 m (indicator of heating fuel combustion) predicted 83% of the total variability of formaldehyde. The models built with the modeling subset were found to predict concentrations well, predicting 62% to 68% of monitored values at validation sites. Traffic and point source emissions cause substantial variation in street-level exposures

  14. Densities, Viscosities and Related Properties for Binary Mixtures of Sulfolane + p-Xylene, Sulfolane + Ethylbenzene in the Temperature Range from 303.15 K to 353.15 K

    Institute of Scientific and Technical Information of China (English)

    杨长生; 马沛生; 周清

    2004-01-01

    Densities and viscosities of the binary systems of sulfolane + ethylbenzene, sulfolane + p-xylene have been experimentally determined in temperature interval 303.15—353.15 K and at atmospheric pressure for the whole composition range. The excess molar volumes and viscosity deviations were computed. The computed quantities have been fitted to Redlich-Kister equation. Excess molar volumes and viscosity deviation show a systematic change with increasing temperature. Two mixtures exhibit negative excess volumes with a minimum which occurs approximately at χ = 0.5. The effect of the size, shape and interaction of components on excess molar volumes and viscosity deviations is discussed.

  15. Commodity chemical growth to slow in 1993

    International Nuclear Information System (INIS)

    Plishner, E.S.

    1992-01-01

    In their latest chemical outlook, DRI/McGraw-Hill economists characterize 1992 as a peak year for U.S. commodity chemical demand growth, at 4.2%, tapering off to a compound 2.2% between 1993 and 1995. Just as operating rates begin to reach higher levels in 1995, however, DRI forecasts slowing GNP growth. DRI's Ramunas J. Svarcas expects a decline in exports. Those plastics promising the rosiest consumption outlook include melamine-formaldehyde resin, up 9.9% in 1992, from 155 million lbs in 1991, and projected to grow 8.6%/year through 1995; styrene acrylonitrile resin, up 23% this year, from 58 million lbs last year, and growing 8.2%/year through 1995; and unsaturated polyester, up 11.7% this year, from 1.07 billion lbs in 1991, and increasing at 6.5%/year. Methanol is a bright spot, with consumption growing 4.7%, from 11.2 billion lbs in 1991 and 12%/year thereafter. Ortho-xylene managed an impressive 21% rebound from a depressed 1991 level of 783 million lbs, and is expected to continue its recovery at 7.7%/year

  16. 基因芯片研究蟾酥急性毒性及配伍减毒机制%Acute Toxicity of Venenum Bufonis and Compatibility of Heart Musk Protecting Pills by Microarray Expression Analysis

    Institute of Scientific and Technical Information of China (English)

    杨爱文; 范雪梅; 李雪; 梁琼麟; 王义明; 罗国安

    2011-01-01

    利用基因芯片技术研究了蟾酥对大鼠心脏的急性毒性及其组方成麝香保心丸后的配伍减毒机制.通过表达谱芯片检测了药物作用后的基因表达差异,对差异表达基因进行了牛物信息学研究并结合实时荧光定量PCR分析.结果表明,低剂量蟾酥可以通过干扰离子稳态和肌动蛋白构建来影响心脏的收缩,同时还会导致心脏细胞的抗凋亡和脂类代谢等应激反应;高剂量蟾酥除进一步干扰离子稳态和肌动蛋白构建外,还会引发铁离子蓄积,最终可能导致细胞凋亡;且蟾酥对心脏的影响具有剂量依赖性.当蟾酥组方成麝香保心丸后,上述影响均不明显,主要影响血压调节和心肌修复等作用,体现了中药配伍的减毒作用.%The differentially expressed genes involved in acute toxicity and compatibility of Heart Musk Pro tecting Pills(HMP) via cDNA microarray were investigated in this paper. Then the GO and KEGG pathway enrichment analysis were performed as well as the functional analysis and RT-PCR validation of two important genes. The results indicated that the ion homeostasis and actin organization were affected in the low dosage group for Venenum Bufonis. Meanwhile, regulation of anti-apoptosis and fatty acid metabolism could be in duced within 2 h; the myocardial contraction was finally disturbed. The ion homeostasis and actin organization could also be disturbed more quickly in the high dosage group. In addition, the iron accumulation could lead to oxidation reduction and cardiomyocyte apoptosis. For HMP, there were some clinical functions, such as blood pressure regulation and myocardial structure organization. However, the related acute toxicity of Vene num Bufonis was not shown. This paper could provide a novel research strategy in the compatibility study of traditional Chinese medicine( TCM ).

  17. Chemical Peels

    Science.gov (United States)

    ... for Every Season How to Choose the Best Skin Care Products In This Section Dermatologic Surgery What is dermatologic ... for Every Season How to Choose the Best Skin Care Products Chemical Peels Uses for Chemical Peels Learn more ...

  18. Chemical Oscillations

    Indian Academy of Sciences (India)

    IMTECH),. Chandigarh. Praveen Kumar is pursuing his PhD in chemical dynamics at. Panjab University,. Chandigarh. Keywords. Chemical oscillations, autoca-. talYSis, Lotka-Volterra model, bistability, hysteresis, Briggs-. Rauscher reaction.

  19. Physical and toxic properties of hazardous chemicals regularly stored and transported in the vicinity of nuclear installations

    International Nuclear Information System (INIS)

    1976-03-01

    This report gives a compilation of data based on information assembled by the US Nuclear Regulatory Commission and completed by the Safety and Reliability Directorate of the UK AEA, the Dutch Reactor Safety Commission, the French Atomic Energy Commission, and the CSNI Secretariat. Data sheets for a large number of hazardous chemicals are presented (from acetaldehyde to xylene), giving details of their physical and toxic properties such as: molecular weight, boiling point, vapor density, heat of vaporization, toxic concentration in air, flammability limits, toxic effects, vapor pressure data, etc.

  20. Chemical ecotoxicology

    International Nuclear Information System (INIS)

    Paasivirta, J.

    1991-01-01

    This book discusses risk assessment, chemical cycles, structure-activity relations, organohalogens, oil residues, mercury, sampling and analysis of trace chemicals, and emissions from the forestry industry. Topics include: Cycles of chemicals in the environment. Rick assessment and management, strucuture and toxicity, sampling and analysis of trace chemicals in environment, interpretation of the environmental analysis results, mercury in the environment, organohalogen compounds in the environment, emissions from forestry industry, oil residues in the environment: oil spills in the marine environment

  1. Chemical sensor

    Science.gov (United States)

    Rauh, R. David (Inventor)

    1990-01-01

    A sensor for detecting a chemical substance includes an insertion element having a structure which enables insertion of the chemical substance with a resulting change in the bulk electrical characteristics of the insertion element under conditions sufficient to permit effective insertion; the change in the bulk electrical characteristics of the insertion element is detected as an indication of the presence of the chemical substance.

  2. Crystal structure of (1S,2R,6R,7R,8S,12S-4,10,17-triphenyl-15-thia-4,10-diazapentacyclo[5.5.5.01,16.02,6.08,12]heptadeca-13,16-diene-3,5,9,11-tetrone p-xylene hemisolvate

    Directory of Open Access Journals (Sweden)

    Wayland E. Noland

    2014-12-01

    Full Text Available The title tetrone compound, C32H22N2O4S· 0.5C8H10, is the major product (50% yield of an attempted Diels–Alder reaction of 2-(α-styrylthiophene with N-phenylmaleimide (2 equivalents in toluene. Recrystallization of the resulting powder from p-xylene gave the title hemisolvate; the p-xylene molecule is located about an inversion center. In the crystal, the primary tetrone contacts are between a carbonyl O atom and the four flagpole H atoms of the bicyclo[2.2.2]octene core, forming chains along [001].

  3. Early Liver and Kidney Dysfunction Associated with Occupational Exposure to Sub-Threshold Limit Value Levels of Benzene, Toluene, and Xylenes in Unleaded Petrol

    Directory of Open Access Journals (Sweden)

    Masoud Neghab

    2015-12-01

    Conclusion: The average exposure of petrol station workers to BTX did not exceed the current threshold limit values (TLVs for these chemicals. However, evidence of subtle, subclinical and prepathologic early liver and kidney dysfunction was evident in exposed individuals.

  4. [Chemical weapons and chemical terrorism].

    Science.gov (United States)

    Nakamura, Katsumi

    2005-10-01

    Chemical Weapons are kind of Weapons of Mass Destruction (WMD). They were used large quantities in WWI. Historically, large quantities usage like WWI was not recorded, but small usage has appeared now and then. Chemical weapons are so called "Nuclear weapon for poor countrys" because it's very easy to produce/possession being possible. They are categorized (1) Nerve Agents, (2) Blister Agents, (3) Cyanide (blood) Agents, (4) Pulmonary Agents, (5) Incapacitating Agents (6) Tear Agents from the viewpoint of human body interaction. In 1997 the Chemical Weapons Convention has taken effect. It prohibits chemical weapons development/production, and Organization for the Prohibition of Chemical Weapons (OPCW) verification regime contributes to the chemical weapons disposal. But possibility of possession/use of weapons of mass destruction by terrorist group represented in one by Matsumoto and Tokyo Subway Sarin Attack, So new chemical terrorism countermeasures are necessary.

  5. Hazardous Chemicals

    Centers for Disease Control (CDC) Podcasts

    Chemicals are a part of our daily lives, providing many products and modern conveniences. With more than three decades of experience, The Centers for Disease Control and Prevention (CDC) has been in the forefront of efforts to protect and assess people's exposure to environmental and hazardous chemicals. This report provides information about hazardous chemicals and useful tips on how to protect you and your family from harmful exposure.

  6. Alarms, Chemical

    Science.gov (United States)

    cited in applicable qualitative materiel requirements, small development requirements, technical characteristics, and other requirements and documentation that pertain to automatic chemical agent alarms.

  7. Chemical oceanography

    National Research Council Canada - National Science Library

    Millero, F.J

    1996-01-01

    Chemical Oceanography presents a comprehensive examination of the chemistry of oceans through discussions of such topics as descriptive physical oceanography, the composition of seawater and the major...

  8. Determinação de benzeno, tolueno, etilbenzeno e xilenos em gasolina comercializada nos postos do estado do Piauí Determination of benzene, toluene, ethylbenzene and xylenes in commercial gasoline from Piaui state

    Directory of Open Access Journals (Sweden)

    Flamys Lena do N. Silva

    2009-01-01

    Full Text Available Automotive gasoline consists of a complex mixture of flammable and volatile hydrocarbons derived from crude oil with carbon numbers within the range of 4-12 and boiling points range of 30-225 ºC. Its composition varies with the kind of crude oil and the type of refinery process that they undergone. Aromatics hydrocarbons, in particular benzene, toluene, ethylbenzene and isomeric xylenes (BTEX are the toxic group constituents presents. GC-FID was employed to quantify these hydrocarbons in 50 commercial gasoline samples from Piauí state. Statistical analysis techniques, such as PCA and HCA were used to analyze the data. Moreover, several validation parameters were evaluated.

  9. Chemical Emergencies - Multiple Languages

    Science.gov (United States)

    ... Chemical Emergencies - bosanski (Bosnian) PDF Chemical Emergencies - English MP3 Chemical Emergencies - bosanski (Bosnian) MP3 Chemical Emergencies - English MP4 Chemical Emergencies - bosanski (Bosnian) ...

  10. Musk as a Pheromone? Didactic Exercise.

    Science.gov (United States)

    Bersted, Chris T.

    A classroom/laboratory exercise has been used to introduce college students to factorial research designs, differentiate between interpretations for experimental and quasi-experimental variables, and exemplify application of laboratory research methods to test practical questions (advertising claims). The exercise involves having randomly divided…

  11. Effect of chemical modification on behavior of various organic vanadium forms during analysis by electrothermal atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Kowalewska, Zofia

    2007-01-01

    The behavior of various organic V forms dissolved in xylene during analysis by electrothermal atomic absorption spectrometry (ETAAS) was compared. The investigated analyte forms included compounds with vanadium at the oxidation state III, IV or V, as well as N, O or S atoms in molecules. Another group consisted of petroleum products containing naturally-occurring V species. Although the characteristic mass determined under different analytical conditions was in the very wide range from 11 up to 55 pg, some rules of V behavior were found. In the case of porphyrins and petroleum products, the application of Pd as a chemical modifier (xylene solution of Pd(II) acetylacetonate) seemed to be crucial. It was shown that Pd must be introduced to a furnace together with a sample. Pd injected and thermally pretreated before the sample injection was less effective for porphyrins and the petroleum products, but it increased signals of V compounds containing O as donor atom. The iodine pretreatment followed by the methyltrioctylammonium chloride (MTOACl) pretreatment was advantageous for these V forms. The air ashing in a graphite tube appeared to be important to improve decomposition of the petroleum products. No significant influence of the V oxidation state on the analytical signal was observed. The behavior of V contained in two Conostan oil standards, the single-element and the S21 multielement standard, was different in many situations. Probably, the joint action of other elements is responsible for this effect. In general, chemical modification was applied in the work for two reasons: to reduce the V volatility (in some cases losses at about 300 deg. C were observed) and to enhance the atomization efficiency. For routine analysis air ashing, modification by Pd introduced into the furnace together with the sample solution and petroleum products with known V content as standard is recommended. Using this procedure the characteristic mass varied from 16 to 19 pg for

  12. Hazardous Chemicals

    Centers for Disease Control (CDC) Podcasts

    2007-04-10

    Chemicals are a part of our daily lives, providing many products and modern conveniences. With more than three decades of experience, The Centers for Disease Control and Prevention (CDC) has been in the forefront of efforts to protect and assess people's exposure to environmental and hazardous chemicals. This report provides information about hazardous chemicals and useful tips on how to protect you and your family from harmful exposure.  Created: 4/10/2007 by CDC National Center for Environmental Health.   Date Released: 4/13/2007.

  13. Chemical Peel

    Science.gov (United States)

    ... your expectations. Talk with your doctor about your motivations and expectations, as well as the potential risks. ... the sun permanently to prevent changes in skin color. Keep in mind that chemical peel results might ...

  14. Chemical carcinogens

    National Research Council Canada - National Science Library

    Searle, Charles E

    1976-01-01

    Cancer causing agents are now known to exist throughout the environment-in polluted air and tobacco smoke, in various plants and foods, and in many chemicals that are used in industry and laboratories...

  15. Chemical sensors

    International Nuclear Information System (INIS)

    Hubbard, C.W.; Gordon, R.L.

    1987-05-01

    The revolution in analytical chemistry promised by recent developments in the field of chemical sensors has potential for significant positive impact on both research and production activities conducted by and for the Department of Energy. Analyses which were, in the past, performed only with a roomful of expensive equipment can now be performed with miniature solid-state electronic devices or small optical probes. Progress in the development of chemical sensors has been rapid, and the field is currently growing at a great rate. In accordance, Pacific Northwest Laboratory initiated a survey of recent literature so that contributors to active programs in research on analytical methods could be made aware of principles and applications of this new technology. This report presents the results of that survey. The sensors discussed here are divided into three types: micro solid-state devices, optical sensors, and piezoelectric crystal devices. The report is divided into three corresponding sections. The first section, ''Micro Solid-State Devices,'' discusses the design, operation, and application of electronic sensors that are produced in much the same way as standard solid-state electronic devices. The second section, ''Optrodes,'' covers the design and operation of chemical sensors that use fiber optics to detect chemically induced changes in optical properties. The final section, ''Piezoelectric Crystal Detectors,'' discusses two types of chemical sensors that depend on the changes in the properties of an oscillating piezoelectric crystal to detect the presence of certain materials. Advantages and disadvantages of each type of sensor are summarized in each section

  16. Determination of As and Se in crude oil diluted in xylene by inductively coupled plasma mass spectrometry using a dynamic reaction cell for interference correction on {sup 80}Se

    Energy Technology Data Exchange (ETDEWEB)

    Albuquerque, Fernanda Inda de [Departamento de Quimica, Pontificia Universidade Catolica do Rio de Janeiro (PUC-Rio), Rua Marques de Sao Vicente 225, 22451-900 Rio de Janeiro, RJ (Brazil); Duyck, Christiane B., E-mail: cbduyck@vm.uff.br [Departamento de Quimica, Pontificia Universidade Catolica do Rio de Janeiro (PUC-Rio), Rua Marques de Sao Vicente 225, 22451-900 Rio de Janeiro, RJ (Brazil); Departamento de Quimica, Universidade Federal Fluminense (UFF), Outeiro Sao Joao Batista s/n, Centro, 24020-150, Niteroi, RJ (Brazil); Fonseca, Teresa Cristina O. [Centro de Pesquisas Leopoldo A. Miguez de Mello da Petrobras (CENPES) (Brazil); Saint' Pierre, Tatiana D. [Departamento de Quimica, Pontificia Universidade Catolica do Rio de Janeiro (PUC-Rio), Rua Marques de Sao Vicente 225, 22451-900 Rio de Janeiro, RJ (Brazil)

    2012-05-15

    Arsenic and selenium can be found in crude oils and represent an important source of pollution when released to the environment during any stage of extraction or refinery. These elements present low sensitivity in the direct determination by inductively coupled plasma mass spectrometry (ICP-MS), due to their high ionization potential, and are also prone to spectral interferences. Hydride generation (HG) can be alternatively employed for the separation of these analytes from the sample matrix and introduction into the instrument. However, the required sample preparation usually increases the analysis time. In this work, a method was developed for the determination of As and Se in crude oil by ICP-MS, after sample dilution in xylene. The use of a dynamic reaction cell (DRC) allowed for the overcoming of Ar{sub 2}{sup +} interference on {sup 80}Se, but was not necessary for As, since interference on m/z 75 was not observed. The optimized operational conditions for {sup 75}As and {sup 80}Se were: 1350 W of RF power, 0.4 L min{sup -1} of Ar nebulizer and 0.7 L min{sup -1} of Ar auxiliary flow rates. The DRC conditions for {sup 80}Se were 0.5 L min{sup -1} of methane and rejection parameter q (Rpq) of 0.2. The analyses were carried out by analyte addition and the limits of detection (LOD) were 0.04 {mu}g kg{sup -1} for As and 0.1 {mu}g kg{sup -1} for Se. The accuracy was verified by the analysis of residual fuel oil certified material, with agreement at a 95% confidence level. Nine Brazilian crude oil samples were analyzed and the results compared to those obtained by hydride generation ICP-MS. In this case, samples were decomposed with nitric acid in a digester block, the analytes pre-reduced with HCl 6 mol L{sup -1} and the determination carried out by external calibration. Although better instrumental LODs were obtained by HG (0.002 {mu}g kg{sup -1} of As and 0.04 {mu}g kg{sup -1} of Se), the direct determination of As and Se in crude oil diluted in xylene by DRC

  17. Evaluation of seawater contamination with benzene, toluene and xylene in the Ubatuba north coast, SP region, and study of their removal by ionizing radiation; Avaliacao da contaminacao da agua do mar por benzeno, tolueno e xileno na regiao de Ubatuba, litoral norte (SP) e estudo da degradacao destes compostos por radiacao ionizante

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, Kelly Cristina Santana de

    2006-07-01

    A major concern with leaking petroleum is the environmental contamination by the toxic and low water-soluble components such as benzene, toluene, and xylenes (BTX). These hydrocarbons have relatively high pollution potential because of their significant toxicity. The objective of this study was to evaluate the contamination of seawater by the main pollutants of the output and transport of petroleum, such as benzene, toluene, and xylene, and their removal by the exposure to the ionizing radiation. The studied region was Ubatuba region, SP, between 23 deg 26'S and 23 deg 46'S of latitude and 45 deg 02'W and 45 deg 11'W of longitude, area of carry and output of petroleum, and samples were collected from November, 2003 to July, 2005. For BTX in seawater analysis, the Purge and Trap concentrator with FIDGC detector showed significantly higher sensibility than Head Space concentrator with MSGC detector. The minimal detected limits (MDL) obtained at FIDGC were of 0.50 {mu}g/L for benzene, 0.70 {mu}g/L for toluene, and 1.54 {mu}g/L for xylene, and the obtained experimental variability was 15%. While the concentrator type Headspace system with MS detector showed higher MLD, about of 9.30 mg/L for benzene, 8.50 mg/L for toluene, and 9.80 mg/L for xylene, and 10% of experimental variability. In the studied area the benzene concentration varied from 1.0 {mu}g/L to 2.0 {mu}g/L, the concentration of toluene varied from < 0.70 {mu}g/L to 3.24 {mu}g/L and the maximum value of xylene observed was of 2.92 {mu}g/L. The seawater samples contaminated with BTX standard and exposed to ionizing radiation using a source of {sup 60}Co, presented a removal from 10% to 40% of benzene at 20 kGy absorbed doses and concentration of 35.1 mg/L and 70.2 mg/L, respectively; from 20% to 60% of toluene removal with 15 kGy absorbed dose and from 20% to 80% of xylene with 15 kGy absorbed dose in similar concentrations. (author)

  18. Evaluation of seawater contamination with benzene, toluene and xylene in the Ubatuba north coast, SP region, and study of their removal by ionizing radiation; Avaliacao da contaminacao da agua do mar por benzeno, tolueno e xileno na regiao de Ubatuba, litoral norte (SP) e estudo da degradacao destes compostos por radiacao ionizante

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, Kelly Cristina Santana de

    2006-07-01

    A major concern with leaking petroleum is the environmental contamination by the toxic and low water-soluble components such as benzene, toluene, and xylenes (BTX). These hydrocarbons have relatively high pollution potential because of their significant toxicity. The objective of this study was to evaluate the contamination of seawater by the main pollutants of the output and transport of petroleum, such as benzene, toluene, and xylene, and their removal by the exposure to the ionizing radiation. The studied region was Ubatuba region, SP, between 23 deg 26'S and 23 deg 46'S of latitude and 45 deg 02'W and 45 deg 11'W of longitude, area of carry and output of petroleum, and samples were collected from November, 2003 to July, 2005. For BTX in seawater analysis, the Purge and Trap concentrator with FIDGC detector showed significantly higher sensibility than Head Space concentrator with MSGC detector. The minimal detected limits (MDL) obtained at FIDGC were of 0.50 {mu}g/L for benzene, 0.70 {mu}g/L for toluene, and 1.54 {mu}g/L for xylene, and the obtained experimental variability was 15%. While the concentrator type Headspace system with MS detector showed higher MLD, about of 9.30 mg/L for benzene, 8.50 mg/L for toluene, and 9.80 mg/L for xylene, and 10% of experimental variability. In the studied area the benzene concentration varied from 1.0 {mu}g/L to 2.0 {mu}g/L, the concentration of toluene varied from < 0.70 {mu}g/L to 3.24 {mu}g/L and the maximum value of xylene observed was of 2.92 {mu}g/L. The seawater samples contaminated with BTX standard and exposed to ionizing radiation using a source of {sup 60}Co, presented a removal from 10% to 40% of benzene at 20 kGy absorbed doses and concentration of 35.1 mg/L and 70.2 mg/L, respectively; from 20% to 60% of toluene removal with 15 kGy absorbed dose and from 20% to 80% of xylene with 15 kGy absorbed dose in similar concentrations. (author)

  19. Effects of physical and chemical heterogeneity on water-quality samples obtained from wells

    Science.gov (United States)

    Reilly, Thomas E.; Gibs, Jacob

    1993-01-01

    Factors that affect the mass of chemical constituents entering a well include the distributions of flow rate and chemical concentrations along and near the screened or open section of the well. Assuming a layered porous medium (with each layer being characterized by a uniform hydraulic conductivity and chemical concentration), a knowledge of the flow from each layer along the screened zone and of the chemical concentrations in each layer enables the total mass entering the well to be determined. Analyses of hypothetical systems and a site at Galloway, NJ, provide insight into the temporal variation of water-quality data observed when withdrawing water from screened wells in heterogeneous ground-water systems.The analyses of hypothetical systems quantitatively indicate the cause-and-effect relations that cause temporal variability in water samples obtained from wells. Chemical constituents that have relatively uniform concentrations with depth may not show variations in concentrations in the water discharged from a well after the well is purged (evacuation of standing water in the well casing). However, chemical constituents that do not have uniform concentrations near the screened interval of the well may show variations in concentrations in the well discharge water after purging because of the physics of ground-water flow in the vicinity of the screen.Water-quality samples were obtained through time over a 30 minute period from a site at Galloway, NJ. The water samples were analyzed for aromatic hydrocarbons, and the data for benzene, toluene, and meta+para xylene were evaluated for temporal variations. Samples were taken from seven discrete zones, and the flow-weighted concentrations of benzene, toluene, and meta+para xylene all indicate an increase in concentration over time during pumping. These observed trends in time were reproduced numerically based on the estimated concentration distribution in the aquifer and the flow rates from each zone.The results of

  20. Chemical pneumonitis

    Science.gov (United States)

    ... cleaning materials such as chlorine bleach, during industrial accidents, or near swimming pools) Grain and fertilizer dust ... and the A.D.A.M. Editorial team. Chemical Emergencies ... about A.D.A.M.'s editorial policy , editorial process and privacy policy . A.D.A.M. is ...

  1. Chemical dispersants

    NARCIS (Netherlands)

    Rahsepar, Shokouhalsadat; Smit, Martijn P.J.; Murk, Albertinka J.; Rijnaarts, Huub H.M.; Langenhoff, Alette A.M.

    2016-01-01

    Chemical dispersants were used in response to the Deepwater Horizon oil spill in the Gulf of Mexico, both at the sea surface and the wellhead. Their effect on oil biodegradation is unclear, as studies showed both inhibition and enhancement. This study addresses the effect of Corexit on oil

  2. Excess Molar Volume, Viscosity and Heat Capacity for the Binary Mixture of p-Xylene and Acetic Acid at Different Temperatures%对二甲苯和醋酸二元液体混合物在不同温度下的超额摩尔体积、粘度和热容

    Institute of Scientific and Technical Information of China (English)

    杨长生; 马沛生; 唐多强; 尹秋响; 赵长伟

    2002-01-01

    Experimental densities, viscosities and heat capacities at different temperatures were presented overthe entire range of mole fraction for the binary mixture of p-xylene and acetic acid. Density values were used in thedetermination of excess molar volumes, VE. At the same time, the excess viscosity and excess molar heat capacitieswere calculated. The values of VE, ηE and cpE were fitted to the Redlich-Kister equation. Good agreements wereobserved. The excess molar volumes are positive with a large maximum value located in the central concentrationrange. The excess viscosity has an opposite trend to the excess molar volume VE. ηE values are negative over theentire range of the mixture. The cure of dependence of cEp on concentration has a special shape. The molecularinteraction between p-xylene and acetic acid is discussed.

  3. An Active Alkali-Exchanged Faujasite Catalyst for p-Xylene Production via the One-Pot Diels-Alder Cycloaddition/Dehydration Reaction of 2,5-Dimethylfuran with Ethylene.

    Science.gov (United States)

    Rohling, Roderigh Y; Uslamin, Evgeny; Zijlstra, Bart; Tranca, Ionut C; Filot, Ivo A W; Hensen, Emiel J M; Pidko, Evgeny A

    2018-02-02

    The one-pot Diels-Alder cycloaddition (DAC)/dehydration (D) tandem reaction between 2,5-dimethylfuran and ethylene is a potent pathway toward biomass-derived p -xylene. In this work, we present a cheap and active low-silica potassium-exchanged faujasite (KY, Si/Al = 2.6) catalyst. Catalyst optimization was guided by a computational study of the DAC/D reaction mechanism over different alkali-exchanged faujasites using periodic density functional theory calculations complemented by microkinetic modeling. Two types of faujasite models were compared, i.e., a high-silica alkali-exchanged faujasite model representing isolated active cation sites and a low-silica alkali-exchanged faujasite in which the reaction involves several cations in the proximity. The mechanistic study points to a significant synergetic cooperative effect of the ensemble of cations in the faujasite supercage on the DAC/D reaction. Alignment of the reactants by their interactions with the cationic sites and stabilization of reaction intermediates contribute to the high catalytic performance. Experiments confirmed the prediction that KY is the most active catalyst among low-silica alkali-exchanged faujasites. This work is an example of how the catalytic reactivity of zeolites depends on multiple interactions between the zeolite and reagents.

  4. Catalytic oxidation of volatile organic compounds (n-hexane, benzene, toluene, o-xylene promoted by cobalt catalysts supported on γ-Al2O3-CeO2

    Directory of Open Access Journals (Sweden)

    R. Balzer

    2014-09-01

    Full Text Available Cobalt catalysts supported on γ-alumina, ceria and γ-alumina-ceria, with 10 or 20%wt of cobalt load, prepared by the wet impregnation method and characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, field emission transmission electron microscopy (FETEM, N2 adsorption-desorption isotherms (BET/BJH methods, energy-dispersive X-ray spectroscopy (EDX, X-ray photoemission spectroscopy (XPS, O2-chemisorption and temperature programmed reduction (TPR were used to promote the oxidation of volatile organic compounds (n-hexane, benzene, toluene and o-xylene. For a range of low temperatures (50-350 °C, the activity of the catalysts with a higher cobalt load (20% wt was greater than that of the catalysts with a lower cobalt load (10% wt. The Co/γ-Al2O3-CeO2 catalytic systems presented the best performances. The results obtained in the characterization suggest that the higher catalytic activity of the Co20/γ-Al2O3-CeO2 catalyst may be attributed to the higher metal content and amount of oxygen vacancies, as well as the effects of the interaction between the cobalt and the alumina and cerium oxides.

  5. Distinguishing Petroleum (Crude Oil and Fuel) From Smoke Exposure within Populations Based on the Relative Blood Levels of Benzene, Toluene, Ethylbenzene, and Xylenes (BTEX), Styrene and 2,5-Dimethylfuran by Pattern Recognition Using Artificial Neural Networks.

    Science.gov (United States)

    Chambers, D M; Reese, C M; Thornburg, L G; Sanchez, E; Rafson, J P; Blount, B C; Ruhl, J R E; De Jesús, V R

    2018-01-02

    Studies of exposure to petroleum (crude oil/fuel) often involve monitoring benzene, toluene, ethylbenzene, xylenes (BTEX), and styrene (BTEXS) because of their toxicity and gas-phase prevalence, where exposure is typically by inhalation. However, BTEXS levels in the general U.S. population are primarily from exposure to tobacco smoke, where smokers have blood levels on average up to eight times higher than nonsmokers. This work describes a method using partition theory and artificial neural network (ANN) pattern recognition to classify exposure source based on relative BTEXS and 2,5-dimethylfuran blood levels. A method using surrogate signatures to train the ANN was validated by comparing blood levels among cigarette smokers from the National Health and Nutrition Examination Survey (NHANES) with BTEXS and 2,5-dimethylfuran signatures derived from the smoke of machine-smoked cigarettes. Classification agreement for an ANN model trained with relative VOC levels was up to 99.8% for nonsmokers and 100.0% for smokers. As such, because there is limited blood level data on individuals exposed to crude oil/fuel, only surrogate signatures derived from crude oil and fuel were used for training the ANN. For the 2007-2008 NHANES data, the ANN model assigned 7 out of 1998 specimens (0.35%) and for the 2013-2014 NHANES data 12 out of 2906 specimens (0.41%) to the crude oil/fuel signature category.

  6. Chemical radioprotection

    International Nuclear Information System (INIS)

    Siegel, G.

    1979-01-01

    A reivew of the problems and progress in the field of chemical radioprotection is given. After defining the field of research, the practical significance of radioprotective substances and the requirements for a utilizable radioprotective preparation are presented. Trends of development of this field of research, the state of the art, and resulting conclusions for the future development of radioprotective substances of practical value are discussed. (author)

  7. Chemical exposures in recently renovated low-income housing: Influence of building materials and occupant activities.

    Science.gov (United States)

    Dodson, Robin E; Udesky, Julia O; Colton, Meryl D; McCauley, Martha; Camann, David E; Yau, Alice Y; Adamkiewicz, Gary; Rudel, Ruthann A

    2017-12-01

    Health disparities in low-income communities may be linked to residential exposures to chemicals infiltrating from the outdoors and characteristics of and sources in the home. Indoor sources comprise those introduced by the occupant as well as releases from building materials. To examine the impact of renovation on indoor pollutants levels and to classify chemicals by predominant indoor sources, we collected indoor air and surface wipes from newly renovated "green" low-income housing units in Boston before and after occupancy. We targeted nearly 100 semivolatile organic compounds (SVOCs) and volatile organic compounds (VOCs), including phthalates, flame retardants, fragrance chemicals, pesticides, antimicrobials, petroleum chemicals, chlorinated solvents, and formaldehyde, as well as particulate matter. All homes had indoor air concentrations that exceeded available risk-based screening levels for at least one chemical. We categorized chemicals as primarily influenced by the occupant or as having building-related sources. While building-related chemicals observed in this study may be specific to the particular housing development, occupant-related findings might be generalizable to similar communities. Among 58 detected chemicals, we distinguished 25 as primarily occupant-related, including fragrance chemicals 6-acetyl-1,1,2,4,4,7-hexamethyltetralin (AHTN) and 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[g]-2-benzopyran (HHCB). The pre- to post-occupancy patterns of the remaining chemicals suggested important contributions from building materials for some, including dibutyl phthalate and xylene, whereas others, such as diethyl phthalate and formaldehyde, appeared to have both building and occupant sources. Chemical classification by source informs multi-level exposure reduction strategies in low-income housing. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  8. Household Chemical Emergencies

    Science.gov (United States)

    ... Content Home Be Informed Household Chemical Emergencies Household Chemical Emergencies Although the risk of a chemical accident ... reduce the risk of injury. Before a Household Chemical Emergency It is critical to store household chemicals ...

  9. Chemical composition of surgical smoke formed in the abdominal cavity during laparoscopic cholecystectomy – Assessment of the risk to the patient

    Directory of Open Access Journals (Sweden)

    Miłosz Dobrogowski

    2014-04-01

    Full Text Available Objectives: The aim of this study was to assess the exposure of patients to organic substances produced and identified in surgical smoke formed in the abdominal cavity during laparoscopic cholecystectomy. Material and Methods: Identification of these substances in surgical smoke was performed by the use of gas chromatography-mass spectrometry (GC-MS with selective ion monitoring (SIM. The selected biomarkers of exposure to surgical smoke included benzene, toluene, ethylbenzene and xylene. Their concentrations in the urine samples collected from each patient before and after the surgery were determined by SPME-GC/MS. Results: Qualitative analysis of the smoke produced during laparoscopic procedures revealed the presence of a wide variety of potentially toxic chemicals such as benzene, toluene, xylene, dioxins and other substances. The average concentrations of benzene and toluene in the urine of the patients who underwent laparoscopic cholecystectomy, in contrast to the other determined compounds, were significantly higher after the surgery than before it, which indicates that they were absorbed. Conclusions: The source of the compounds produced in the abdominal cavity during the surgery is tissue pyrolysis in the presence of carbon dioxide atmosphere. All patients undergoing laparoscopic procedures are at risk of absorbing and excreting smoke by-products. Exposure of the patient to emerging chemical compounds is usually a one-time and short-term incident, yet concentrations of benzene and toluene found in the urine were significantly higher after the surgery than before it.

  10. Chemical cosmology

    CERN Document Server

    Boeyens, Jan CA

    2010-01-01

    The composition of the most remote objects brought into view by the Hubble telescope can no longer be reconciled with the nucleogenesis of standard cosmology and the alternative explanation, in terms of the LAMBDA-Cold-Dark-Matter model, has no recognizable chemical basis. A more rational scheme, based on the chemistry and periodicity of atomic matter, opens up an exciting new interpretation of the cosmos in terms of projective geometry and general relativity. The response of atomic structure to environmental pressure predicts non-Doppler cosmical redshifts and equilibrium nucleogenesis by alp

  11. Method development and optimization for the determination of benzene, toluene, ethylbenzene and xylenes in water at trace levels by static headspace extraction coupled to gas chromatography-barrier ionization discharge detection.

    Science.gov (United States)

    Pascale, Raffaella; Bianco, Giuliana; Calace, Stefania; Masi, Salvatore; Mancini, Ignazio M; Mazzone, Giuseppina; Caniani, Donatella

    2018-05-04

    Benzene, toluene, ethylbenzene, and xylenes, more commonly named BTEX, represent one of the most ubiquitous and hazardous groups of atmospheric pollutants. The goal of our research was the trace quantification of BTEX in water by using a new simple, low-cost, and accurate method, based on headspace (HS) extraction and gas chromatography (GC) coupled to barrier ionization discharge detector (BID). This water application dealt with simple matrices without protein, fat, or humic material that adsorb target analytes, thus the external standard calibration was suitable to quantify each compound. The validation steps included the study of linearity, detection and quantification limits, and accuracy. LODs and LOQs varied from 0.159 to 1.845 μg/L and from 0.202 to 2.452 μg/L, respectively. The recovery was between 0.74 ± 0.13 and 1.15 ± 0.09; relative standard deviations (% RDSs) were less than 12.81% (n = 5) and 14.84% (n = 10). Also, GC performance was evaluated in term of efficiency, peak tailing and resolution. Preliminary results from practical applications to analyses of real samples are presented. The results indicate that static HS coupled to GC-BID is a successful method for BTEX analysis in water samples at the μg/L levels, provided that hydrocarbons interference occur at similar concentration levels. GC-BID may become a routine reference method alongside the official analytical techniques for quality control purposes of contaminated waters. Moreover, the new method is amenable to automation by using commercial HS units. Copyright © 2018. Published by Elsevier B.V.

  12. Lab-In-Syringe automation of stirring-assisted room-temperature headspace extraction coupled online to gas chromatography with flame ionization detection for determination of benzene, toluene, ethylbenzene, and xylenes in surface waters.

    Science.gov (United States)

    Horstkotte, Burkhard; Lopez de Los Mozos Atochero, Natalia; Solich, Petr

    2018-06-22

    Online coupling of Lab-In-Syringe automated headspace extraction to gas chromatography has been studied. The developed methodology was successfully applied to surface water analysis using benzene, toluene, ethylbenzene, and xylenes as model analytes. The extraction system consisted of an automatic syringe pump with a 5 mL syringe into which all solutions and air for headspace formation were aspirated. The syringe piston featured a longitudinal channel, which allowed connecting the syringe void directly to a gas chromatograph with flame ionization detector via a transfer capillary. Gas injection was achieved via opening a computer-controlled pinch valve and compressing the headspace, upon which separation was initialized. Extractions were performed at room temperature; yet sensitivity comparable to previous work was obtained by high headspace to sample ratio V HS /V Sample of 1.6:1 and injection of about 77% of the headspace. Assistance by in-syringe magnetic stirring yielded an about threefold increase in extraction efficiency. Interferences were compensated by using chlorobenzene as an internal standard. Syringe cleaning and extraction lasting over 10 min was carried out in parallel to the chromatographic run enabling a time of analysis of <19 min. Excellent peak area repeatabilities with RSD of <4% when omitting and <2% RSD when using internal standard corrections on 100 μg L -1 level were achieved. An average recovery of 97.7% and limit of detection of 1-2 μg L -1 were obtained in analyses of surface water. Copyright © 2018 Elsevier B.V. All rights reserved.

  13. CAMEO Chemicals Software

    Science.gov (United States)

    CAMEO Chemicals is an extensive chemical database, available for download, with critical response information for thousands of chemicals, and a tool that tells you what reactions might occur if chemicals were mixed together.

  14. CHEMICAL EVOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Calvin, Melvin

    1965-06-01

    How did life come to be on the surface of the earth? Darwin himself recognized that his basic idea of evolution by variation and natural selection must be a continuous process extending backward in time through that period in which the first living things arose and into the period of 'Chemical Evolution' which preceded it. We are approaching the examination of these events by two routes. One is to seek for evidence in the ancient rocks of the earth which were laid down prior to that time in which organisms capable of leaving their skeletons in the rocks to be fossilized were in existence. This period is sometime prior to approximately 600 million years ago. The earth is believed to have taken its present form approximately 4700 million years ago. We have found in rocks whose age is about 1000 million years certain organic molecules which are closely related to the green pigment of plants, chlorophyll. This seems to establish that green plants were already fluorishing prior to that time. We have now found in rocks of still greater age, namely, 2500 million years, the same kinds of molecules mentioned above which can be attributed to the presence of living organisms. If these molecules are as old as the rocks, we have thus shortened the time available for the generation of the complex biosynthetic sequences which give rise to these specific hydrocarbons (polyisoprenoids) to less than 2000 million years.

  15. Thin film nano-photocatalyts with low band gap energy for gas phase degradation of p-xylene: TiO2 doped Cr, UiO66-NH2 and LaBO3 (B  =  Fe, Mn, and Co)

    Science.gov (United States)

    Loc Luu, Cam; Thuy Van Nguyen, Thi; Nguyen, Tri; Nguyen, Phung Anh; Hoang, Tien Cuong; Ha, Cam Anh

    2018-03-01

    By dip-coating technique the thin films of nano-photocatalysts TiO2, Cr-doped TiO2, LaBO3 perovskites (B  =  Fe, Mn, and Co) prepared by sol-gel method, and UiO66-NH2 prepared by a solvothermal were obtained and employed for gas phase degradation of p-xylene. Physicochemical characteristics of the catalysts were examined by the methods of BET, SEM, TEM, XRD, FT-IR, TGA, Raman and UV-vis spectroscopies. The thickness of film was determined by a Veeco-American Dektek 6M instrument. The activity of catalysts was evaluated in deep photooxidation of p-xylene in a microflow reactor at room temperature with the radiation sources of a UV (λ  =  365 nm) and LED lamps (λ  =  400-510 nm). The obtained results showed that TiO2 and TiO2 doped Cr thin films was featured by an anatase phase with nanoparticles of 10-100 nm. Doping TiO2 with 0.1%mol Cr2O3 led to reduce band gap energy from 3.01 down to 1.99 eV and extend the spectrum of photon absorption to the visible region (λ  =  622 nm). LaBO3 perovkite thin films were also featured by a crystal phase with average particle nanosize of 8-40 nm, a BET surface area of 17.6-32.7 m2 g-1 and band gap energy of 1.87-2.20 eV. UiO66-NH2 was obtained in the ball shape of 100-200 nm, a BET surface area of 576 m2 g-1 and a band gap energy of 2.83 eV. The low band gap energy nano-photocatalysts based on Cr-doped TiO2 and LaBO3 perovskites exhibited highly stable and active for photo-degradation of p-xylene in the gas phase under radiation of UV-vis light. Perovskite LaFeO3 and Cr-TiO2 thin films were the best photocatalysts with a decomposition yield being reached up to 1.70 g p-xylene/g cat.

  16. Caractérisation structurale de l'adsorption des isomères para- et meta- du xylène dans la zéolithe de type faujasite BaX Structural Characterization of Para- and Meta- Xylene in Bax Zeolite

    Directory of Open Access Journals (Sweden)

    Mellot C.

    2006-11-01

    . Pour les molécules de méta-xylène, quel que soit le taux de remplissage, les sites occupés sont à proximité des cations (sites SII; lorsque la troisième molécule est introduite, un réarrangement moléculaire est observé. The separation of para-xylene from C8 aromatic by adsorption on a molecular sieve is a field of research in which much work has been done at Institut Français du Pétrole (IFP in recent years. With a view to obtaining a better understanding of the phenomena involved in this separation, the ensuing research aims to characterize the adsorption of para-xylene and meta-xylene isomers in the state of pure bodies in a BaX zeolite, which is a sieve recognized for its high-performance selective properties during competitive adsorptions. The originality of our approach consists in characterizing, on a molecular scale, the adsorption of two isomers in the zeolitic network so as to work out a molecular filling model of the BaX zeolite. Two principal techniques, infrared spectroscopy and neutron diffraction, were chosen for analyzing each of the two isomers, the adsorbate-adsorbent system. The infrared properties of the adsorbate provide exact information concerning the local environment of the xylene molecule in the zeolite as well as on the existence of adsorbate-adsorbent and adsorbate-adsorbate interactions. Infrared spectroscopy was used to examine both the influence of adsorption on the vibrationel properties - integrated frequencies and adsorbances of fundamental modes - of the xylene molecules and the way these same properties evolve as a function of the zeolite coverage. At the same time, neutron diffraction was used to determine, atome by atome, the chrystallographic position of the xylene molecules in the zeolitic network as a function of the coverage. Two coverages were examined, corresponding to 1 mol/sc (molecule per supercage and 3 mol/sc. One of the major consequences was the gaining of an exact knowledge of the interatomic distances and

  17. Chemical Function Predictions for Tox21 Chemicals

    Data.gov (United States)

    U.S. Environmental Protection Agency — Random forest chemical function predictions for Tox21 chemicals in personal care products uses and "other" uses. This dataset is associated with the following...

  18. Mixture effects at very low doses with combinations of anti-androgenic pesticides, antioxidants, industrial pollutant and chemicals used in personal care products

    Energy Technology Data Exchange (ETDEWEB)

    Orton, Frances; Ermler, Sibylle; Kugathas, Subramaniam [Institute for the Environment, Brunel University, Kingston Lane, Uxbridge UB8 3PH (United Kingdom); Rosivatz, Erika [Institute of Chemical Biology, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom); Scholze, Martin [Institute for the Environment, Brunel University, Kingston Lane, Uxbridge UB8 3PH (United Kingdom); Kortenkamp, Andreas, E-mail: andreas.kortenkamp@brunel.ac.uk [Institute for the Environment, Brunel University, Kingston Lane, Uxbridge UB8 3PH (United Kingdom)

    2014-08-01

    Many xenobiotics have been identified as in vitro androgen receptor (AR) antagonists, but information about their ability to produce combined effects at low concentrations is missing. Such data can reveal whether joint effects at the receptor are induced at low levels and may support the prioritisation of in vivo evaluations and provide orientations for the grouping of anti-androgens in cumulative risk assessment. Combinations of 30 AR antagonists from a wide range of sources and exposure routes (pesticides, antioxidants, parabens, UV-filters, synthetic musks, bisphenol-A, benzo(a)pyrene, perfluorooctane sulfonate and pentabromodiphenyl ether) were tested using a reporter gene assay (MDA-kb2). Chemicals were combined at three mixture ratios, equivalent to single components' effect concentrations that inhibit the action of dihydrotesterone by 1%, 10% or 20%. Concentration addition (CA) and independent action were used to calculate additivity expectations. We observed complete suppression of dihydrotestosterone effects when chemicals were combined at individual concentrations eliciting 1%, 10% or 20% AR antagonistic effect. Due to the large number of mixture components, the combined AR antagonistic effects occurred at very low concentrations of individual mixture components. CA slightly underestimated the combined effects at all mixture ratios. In conclusion, large numbers of AR antagonists from a wide variety of sources and exposure routes have the ability of acting together at the receptor to produce joint effects at very low concentrations. Significant mixture effects are observed when chemicals are combined at concentrations that individually do not induce observable AR antagonistic effects. Cumulative risk assessment for AR antagonists should apply grouping criteria based on effects where data are available, rather than on criteria of chemical similarity. - Highlights: • Mixtures of AR antagonists at low individual concentrations cause complete inhibition

  19. Endocrine Disrupting Chemicals (EDCs)

    Science.gov (United States)

    ... Center Pacientes y Cuidadores Hormones and Health The Endocrine System Hormones Endocrine Disrupting Chemicals (EDCs) Steroid and Hormone ... Hormones and Health › Endocrine Disrupting Chemicals (EDCs) The Endocrine System Hormones Endocrine Disrupting Chemicals (EDCs) EDCs Myth vs. ...

  20. Microfluidic chemical reaction circuits

    Science.gov (United States)

    Lee, Chung-cheng [Irvine, CA; Sui, Guodong [Los Angeles, CA; Elizarov, Arkadij [Valley Village, CA; Kolb, Hartmuth C [Playa del Rey, CA; Huang, Jiang [San Jose, CA; Heath, James R [South Pasadena, CA; Phelps, Michael E [Los Angeles, CA; Quake, Stephen R [Stanford, CA; Tseng, Hsian-rong [Los Angeles, CA; Wyatt, Paul [Tipperary, IE; Daridon, Antoine [Mont-Sur-Rolle, CH

    2012-06-26

    New microfluidic devices, useful for carrying out chemical reactions, are provided. The devices are adapted for on-chip solvent exchange, chemical processes requiring multiple chemical reactions, and rapid concentration of reagents.

  1. Chemical Emergencies Overview

    Science.gov (United States)

    ... Address What's this? Submit What's this? Submit Button Chemical Emergencies Overview Recommend on Facebook Tweet Share Compartir ... themselves during and after such an event. What chemical emergencies are A chemical emergency occurs when a ...

  2. LCA of Chemicals and Chemical Products

    DEFF Research Database (Denmark)

    Fantke, Peter; Ernstoff, Alexi

    2018-01-01

    This chapter focuses on the application of Life Cycle Assessment (LCA) to evaluate the environmental performance of chemicals as well as of products and processes where chemicals play a key role. The life cycle stages of chemical products, such as pharmaceuticals drugs or plant protection products......, are discussed and differentiated into extraction of abiotic and biotic raw materials, chemical synthesis and processing, material processing, product manufacturing, professional or consumer product use, and finally end-of-life . LCA is discussed in relation to other chemicals management frameworks and concepts...... including risk assessment , green and sustainable chemistry , and chemical alternatives assessment. A large number of LCA studies focus on contrasting different feedstocks or chemical synthesis processes, thereby often conducting a cradle to (factory) gate assessment. While typically a large share...

  3. Chemical Security Analysis Center

    Data.gov (United States)

    Federal Laboratory Consortium — In 2006, by Presidential Directive, DHS established the Chemical Security Analysis Center (CSAC) to identify and assess chemical threats and vulnerabilities in the...

  4. Evaluation of biomonitoring data from the CDC National Exposure Report in a risk assessment context: perspectives across chemicals.

    Science.gov (United States)

    Aylward, Lesa L; Kirman, Christopher R; Schoeny, Rita; Portier, Christopher J; Hays, Sean M

    2013-03-01

    Biomonitoring data reported in the National Report on Human Exposure to Environmental Chemicals [NER; Centers for Disease Control and Prevention (2012)] provide information on the presence and concentrations of > 400 chemicals in human blood and urine. Biomonitoring Equivalents (BEs) and other risk assessment-based values now allow interpretation of these biomonitoring data in a public health risk context. We compared the measured biomarker concentrations in the NER with BEs and similar risk assessment values to provide an across-chemical risk assessment perspective on the measured levels for approximately 130 analytes in the NER. We identified available risk assessment-based biomarker screening values, including BEs and Human Biomonitoring-I (HBM-I) values from the German Human Biomonitoring Commission. Geometric mean and 95th percentile population biomarker concentrations from the NER were compared to the available screening values to generate chemical-specific hazard quotients (HQs) or cancer risk estimates. Most analytes in the NER show HQ values of chemicals, benzene, xylene, several metals, di-2(ethylhexyl)phthalate, and some legacy organochlorine pesticides) approach or exceed HQ values of 1 or cancer risks of > 1 × 10-4 at the geometric mean or 95th percentile, suggesting exposure levels may exceed published human health benchmarks. This analysis provides for the first time a means for examining population biomonitoring data for multiple environmental chemicals in the context of the risk assessments for those chemicals. The results of these comparisons can be used to focus more detailed chemical-specific examination of the data and inform priorities for chemical risk management and research.

  5. Design of chemical plant

    International Nuclear Information System (INIS)

    Lee, Dong Il; Kim, Seung Jae; Yang, Jae Ho; Ryu, Hwa Won

    1993-01-01

    This book describes design of chemical plant, which includes chemical engineer and plan for chemical plant, development of chemical process, cost engineering pattern, design and process development, general plant construction plan, project engineering, foundation for economy on assets and depreciation, estimation for cost on capital investment and manufacturing cost, design with computers optimal design and method like fluid mechanics design chemical device and estimation for cost, such as dispatch of material and device writing on design report and appendixes.

  6. Nature and prevalence of non-additive toxic effects in industrially relevant mixtures of organic chemicals.

    Science.gov (United States)

    Parvez, Shahid; Venkataraman, Chandra; Mukherji, Suparna

    2009-06-01

    The concentration addition (CA) and the independent action (IA) models are widely used for predicting mixture toxicity based on its composition and individual component dose-response profiles. However, the prediction based on these models may be inaccurate due to interaction among mixture components. In this work, the nature and prevalence of non-additive effects were explored for binary, ternary and quaternary mixtures composed of hydrophobic organic compounds (HOCs). The toxicity of each individual component and mixture was determined using the Vibrio fischeri bioluminescence inhibition assay. For each combination of chemicals specified by the 2(n) factorial design, the percent deviation of the predicted toxic effect from the measured value was used to characterize mixtures as synergistic (positive deviation) and antagonistic (negative deviation). An arbitrary classification scheme was proposed based on the magnitude of deviation (d) as: additive (50%, class-IV) antagonistic/synergistic. Naphthalene, n-butanol, o-xylene, catechol and p-cresol led to synergism in mixtures while 1, 2, 4-trimethylbenzene and 1, 3-dimethylnaphthalene contributed to antagonism. Most of the mixtures depicted additive or antagonistic effect. Synergism was prominent in some of the mixtures, such as, pulp and paper, textile dyes, and a mixture composed of polynuclear aromatic hydrocarbons. The organic chemical industry mixture depicted the highest abundance of antagonism and least synergism. Mixture toxicity was found to depend on partition coefficient, molecular connectivity index and relative concentration of the components.

  7. Kinetics of Natural Attenuation: Review of the Critical Chemical Conditions and Measurements at Bore Scale

    Directory of Open Access Journals (Sweden)

    O. Atteia

    2002-01-01

    Full Text Available This paper describes the chemical conditions that should favour the biodegradation of organic pollutants. Thermodynamic considerations help to define the reaction that can occur under defined chemical conditions. The BTEX (benzene, toluene, ethylbenzene, and xylene degradation is focused on benzene, as it is the most toxic oil component and also because it has the slowest degradation rate under most field conditions. Several studies on benzene degradation allow the understanding of the basic degradation mechanisms and their importance in field conditions. The use of models is needed to interpret field data when transport, retardation, and degradation occur. A detailed comparison of two existing models shows that the limits imposed by oxygen transport must be simulated precisely to reach correct plumes shapes and dimensions, and that first-order kinetic approaches may be misleading. This analysis led us to develop a technique to measure directly biodegradation in the field. The technique to recirculate water at the borehole scale and the CO2 analysis are depicted. First results of biodegradation show that this technique is able to easily detect the degradation of 1 mg/l of hydrocarbons and that, in oxic media, a fast degradation rate of mixed fuel is observed.

  8. Survey of renewable chemicals produced from lignocellulosic biomass during ionic liquid pretreatment

    Directory of Open Access Journals (Sweden)

    Varanasi Patanjali

    2013-01-01

    Full Text Available Abstract Background Lignin is often overlooked in the valorization of lignocellulosic biomass, but lignin-based materials and chemicals represent potential value-added products for biorefineries that could significantly improve the economics of a biorefinery. Fluctuating crude oil prices and changing fuel specifications are some of the driving factors to develop new technologies that could be used to convert polymeric lignin into low molecular weight lignin and or monomeric aromatic feedstocks to assist in the displacement of the current products associated with the conversion of a whole barrel of oil. We present an approach to produce these chemicals based on the selective breakdown of lignin during ionic liquid pretreatment. Results The lignin breakdown products generated are found to be dependent on the starting biomass, and significant levels were generated on dissolution at 160°C for 6 hrs. Guaiacol was produced on dissolution of biomass and technical lignins. Vanillin was produced on dissolution of kraft lignin and eucalytpus. Syringol and allyl guaiacol were the major products observed on dissolution of switchgrass and pine, respectively, whereas syringol and allyl syringol were obtained by dissolution of eucalyptus. Furthermore, it was observed that different lignin-derived products could be generated by tuning the process conditions. Conclusions We have developed an ionic liquid based process that depolymerizes lignin and converts the low molecular weight lignin fractions into a variety of renewable chemicals from biomass. The generated chemicals (phenols, guaiacols, syringols, eugenol, catechols, their oxidized products (vanillin, vanillic acid, syringaldehyde and their easily derivatized hydrocarbons (benzene, toluene, xylene, styrene, biphenyls and cyclohexane already have relatively high market value as commodity and specialty chemicals, green building materials, nylons, and resins.

  9. Chemical Data Reporting Fact Sheet: Chemicals Snapshot

    Science.gov (United States)

    This fact sheet provides a brief overview of the chemical manufacturing, processing, and use information collected for the 2012 Chemical Data Reporting (CDR) rule. Users do not have access to the complete CDR data set and should draw conclusions with care.

  10. chemical safety and chemical security overview

    African Journals Online (AJOL)

    IICBA01

    Wafaa M. Abdou. Chemical Industries Division, National Research Centre, ... substances to attain an acceptably low risk of exposure. Security is: ... Sharing locations of chemicals can publicize targets for theft .... D. Personal Protective Equipments (PPE): ... E. Lighting & Noise Levels ... PPE. ➢ Autoclave or sterilize wastes.

  11. Advances in chemical physics

    CERN Document Server

    Rice, Stuart A

    2012-01-01

    The Advances in Chemical Physics series-the cutting edge of research in chemical physics The Advances in Chemical Physics series provides the chemical physics field with a forum for critical, authoritative evaluations of advances in every area of the discipline. Filled with cutting-edge research reported in a cohesive manner not found elsewhere in the literature, each volume of the Advances in Chemical Physics series serves as the perfect supplement to any advanced graduate class devoted to the study of chemical physics. This volume explores: Quantum Dynamical Resonances in Ch

  12. Personal Chemical Exposure informatics

    Science.gov (United States)

    Chemical Exposure science is the study of human contact with chemicals (from manufacturing facilities, everyday products, waste) occurring in their environments and advances knowledge of the mechanisms and dynamics of events that cause or prevent adverse health outcomes. (adapted...

  13. Capacitive chemical sensor

    Science.gov (United States)

    Manginell, Ronald P; Moorman, Matthew W; Wheeler, David R

    2014-05-27

    A microfabricated capacitive chemical sensor can be used as an autonomous chemical sensor or as an analyte-sensitive chemical preconcentrator in a larger microanalytical system. The capacitive chemical sensor detects changes in sensing film dielectric properties, such as the dielectric constant, conductivity, or dimensionality. These changes result from the interaction of a target analyte with the sensing film. This capability provides a low-power, self-heating chemical sensor suitable for remote and unattended sensing applications. The capacitive chemical sensor also enables a smart, analyte-sensitive chemical preconcentrator. After sorption of the sample by the sensing film, the film can be rapidly heated to release the sample for further analysis. Therefore, the capacitive chemical sensor can optimize the sample collection time prior to release to enable the rapid and accurate analysis of analytes by a microanalytical system.

  14. Chemical Weapons Convention

    National Research Council Canada - National Science Library

    1997-01-01

    On April 29, 1997, the Convention on the Prohibition of the Development, Production, Stockpiling, and Use of Chemical Weapons and on Their Destruction, known as the Chemical Weapons Convention (CWC...

  15. Tobacco and chemicals (image)

    Science.gov (United States)

    Some of the chemicals associated with tobacco smoke include ammonia, carbon dioxide, carbon monoxide, propane, methane, acetone, hydrogen cyanide and various carcinogens. Other chemicals that are associated with chewing ...

  16. Chemical Transformation Simulator

    Science.gov (United States)

    The Chemical Transformation Simulator (CTS) is a web-based, high-throughput screening tool that automates the calculation and collection of physicochemical properties for an organic chemical of interest and its predicted products resulting from transformations in environmental sy...

  17. Chemicals Industry Vision

    Energy Technology Data Exchange (ETDEWEB)

    none,

    1996-12-01

    Chemical industry leaders articulated a long-term vision for the industry, its markets, and its technology in the groundbreaking 1996 document Technology Vision 2020 - The U.S. Chemical Industry. (PDF 310 KB).

  18. Chemical Industry Bandwidth Study

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2006-12-01

    The Chemical Bandwidth Study provides a snapshot of potentially recoverable energy losses during chemical manufacturing. The advantage of this study is the use of "exergy" analysis as a tool for pinpointing inefficiencies.

  19. Chemical Search Web Utility

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Chemical Search Web Utility is an intuitive web application that allows the public to easily find the chemical that they are interested in using, and which...

  20. Chemical cleaning review

    International Nuclear Information System (INIS)

    Dow, B.L.; Thomas, R.C.

    1995-01-01

    Three main chemical processes for cleaning steam generators have evolved from the early work of the industry. Of the more than 50 chemical cleanings carried out to date most have been considered a success by the utilities performing them. (author)

  1. Computing Equilibrium Chemical Compositions

    Science.gov (United States)

    Mcbride, Bonnie J.; Gordon, Sanford

    1995-01-01

    Chemical Equilibrium With Transport Properties, 1993 (CET93) computer program provides data on chemical-equilibrium compositions. Aids calculation of thermodynamic properties of chemical systems. Information essential in design and analysis of such equipment as compressors, turbines, nozzles, engines, shock tubes, heat exchangers, and chemical-processing equipment. CET93/PC is version of CET93 specifically designed to run within 640K memory limit of MS-DOS operating system. CET93/PC written in FORTRAN.

  2. Semivolatile organic compounds in residential air along the Arizona-Mexico border.

    Science.gov (United States)

    Gale, Robert W; Cranor, Walter L; Alvarez, David A; Huckins, James N; Petty, Jimmie D; Robertson, Gary L

    2009-05-01

    Concerns about indoor air quality and the potential effects on people living in these environments are increasing as more reports about the toxicities and the potential indoor air exposure levels of household-use chemicals and chemicals from housing and fumishing manufacture in air are being assessed. Gas chromatography/mass spectromery was used to confirm numerous airborne contaminants obtained from the analysis of semipermeable membrane devices deployed inside of 52 homes situated along the border between Arizona and Mexico. We also describe nontarget analytes in the organochlorine pesticide fractions of 12 of these homes; this fraction is also the most likely to contain the broadest scope of bioconcentratable chemicals accumulated from the indoor air. Approximately 400 individual components were identified, ranging from pesticides to a wide array of hydrocarbons, fragrances such as the musk xylenes, flavors relating to spices, aldehydes, alcohols, esters and phthalate esters, and other miscellaneous types of chemicals. The results presented in this study demonstrate unequivocally that the mixture of airborne chemicals present indoors is far more complex than previously demonstrated.

  3. 'Pharmaceutical and chemical personal care products determination in natural and residual waters; Determinaciond e farmacos y productos quimicos de cuidado personal (PPcps) en aguas naturales y residuales

    Energy Technology Data Exchange (ETDEWEB)

    Jordi, R.; Gomez, M.; Vazquez, M. J.

    2004-07-01

    A quantitative, selected and sensitive method on liquid-liquid extraction (LLE)coupled to analysis by gas chromatography/mass spectrometry (GC/MS) is described for analysis of a selected group of chemicals compounds used as pharmaceuticals and personal care products (PPcPs). They are considered as persistent-emergent pollutants in natural and residual waters. The studied PPCPs- ibuprofen, diclofenac, benzafibrate, diazepan, carbamazepine, galaxolide, tonalide, celestolide, traseolide and cashmeran-are representative for three categories of PPCPs: acids and neutrals pahrmaceuticals and polycyclic synthetic musk, all of them with wide use. The effectiveness of the proposed method was higher than 90% in three different matrix, quantification limits, were at order of ng/L range. The estimated uncertainty was about 23% for all compounds. to asses the performance of the method, natural and wastewaters were analyzed. the obtained results showed that galaxolide, tonalide, ibuprofen, benzafibrate are the most frequently PPCP identified in these waters. Currently, concentrations found in the wastewater are ten times higher than those found in natural waters. No PPCP or very low concentrations were found in the tap water samples analyzed. (Author) 13 refs.

  4. Advances in chemical Physics

    CERN Document Server

    Rice, Stuart A

    2011-01-01

    The Advances in Chemical Physics series-the cutting edge of research in chemical physics The Advances in Chemical Physics series provides the chemical physics and physical chemistry fields with a forum for critical, authoritative evaluations of advances in every area of the discipline. Filled with cutting-edge research reported in a cohesive manner not found elsewhere in the literature, each volume of the Advances in Chemical Physics series offers contributions from internationally renowned chemists and serves as the perfect supplement to any advanced graduate class devoted to the study of che

  5. Advances in chemical physics

    CERN Document Server

    Rice, Stuart A

    2014-01-01

    Advances in Chemical Physics is the only series of volumes available that explores the cutting edge of research in chemical physics. This is the only series of volumes available that presents the cutting edge of research in chemical physics.Includes contributions from experts in this field of research.Contains a representative cross-section of research that questions established thinking on chemical solutions.Structured with an editorial framework that makes the book an excellent supplement to an advanced graduate class in physical chemistry or chemical physics.

  6. Advances in chemical physics

    CERN Document Server

    Rice, Stuart A

    2011-01-01

    The Advances in Chemical Physics series-the cutting edge of research in chemical physics The Advances in Chemical Physics series provides the chemical physics and physical chemistry fields with a forum for critical, authoritative evaluations of advances in every area of the discipline. Filled with cutting-edge research reported in a cohesive manner not found elsewhere in the literature, each volume of the Advances in Chemical Physics series offers contributions from internationally renowned chemists and serves as the perfect supplement to any advanced graduate class devoted to the study of che

  7. The chemical juggernaut.

    Science.gov (United States)

    Cadbury, D

    1997-01-01

    Man-made chemicals pervade and support every aspect of modern living. The chemical industry has become such a powerful force in the global economy, sales of synthetic chemicals and products derived from them constitute well in excess of a third of the world's gross national product. But, these man-made chemicals are also 'elixirs of death,' the symbol of human destruction. Laboratory tests have shown that a number of chemicals in common use possess a remarkable property: they can weakly mimic or modify the action of human hormones. It has been proven that some chemicals found in plastics, pesticides, and industrial products are weakly estrogenic, modifying the action of the female hormone. In addition, other chemicals affect the male hormones, androgens, or anti-androgens; others are thought to target different hormone systems, such as thyroid and adrenal glands. Many research studies are being conducted to establish the impact of chemicals on human health. Of special concern are the rising incidence of testicular cancer, decline in human sperm counts, and the sharp rise of breast cancer. In conclusion, although there is a worldwide debate on the effects of chemical exposure on humans, the significance of findings for human health, concerning testicular and breast cancer, are still unknown. An international treaty is called for to control the use of the persistent hormonally active chemicals.

  8. Chemical bond fundamental aspects of chemical bonding

    CERN Document Server

    Frenking, Gernot

    2014-01-01

    This is the perfect complement to ""Chemical Bonding - Across the Periodic Table"" by the same editors, who are two of the top scientists working on this topic, each with extensive experience and important connections within the community. The resulting book is a unique overview of the different approaches used for describing a chemical bond, including molecular-orbital based, valence-bond based, ELF, AIM and density-functional based methods. It takes into account the many developments that have taken place in the field over the past few decades due to the rapid advances in quantum chemica

  9. Chemical and biological weapons

    International Nuclear Information System (INIS)

    Harris, E.D.

    1991-01-01

    This paper discusses the prospects of the multilateral negotiations aimed at achieving a complete and total ban on chemical weapons the Chemical Weapons convention (CWC). The control of the proliferation of chemical weapons is no longer just on East-West issue; it is also an issue of concern in Third World Countries, and in some of the wealthier middle eastern nations, such as Kuwait

  10. Biofiltration of airborne VOCs with green wall systems-Microbial and chemical dynamics.

    Science.gov (United States)

    Mikkonen, A; Li, T; Vesala, M; Saarenheimo, J; Ahonen, V; Kärenlampi, S; Blande, J D; Tiirola, M; Tervahauta, A

    2018-05-06

    Botanical air filtration is a promising technology for reducing indoor air contaminants, but the underlying mechanisms need better understanding. Here, we made a set of chamber fumigation experiments of up to 16 weeks of duration, to study the filtration efficiencies for seven volatile organic compounds (VOCs; decane, toluene, 2-ethylhexanol, α-pinene, octane, benzene, and xylene) and to monitor microbial dynamics in simulated green wall systems. Biofiltration functioned on sub-ppm VOC levels without concentration-dependence. Airflow through the growth medium was needed for efficient removal of chemically diverse VOCs, and the use of optimized commercial growth medium further improved the efficiency compared with soil and Leca granules. Experimental green wall simulations using these components were immediately effective, indicating that initial VOC removal was largely abiotic. Golden pothos plants had a small additional positive impact on VOC filtration and bacterial diversity in the green wall system. Proteobacteria dominated the microbiota of rhizosphere and irrigation water. Airborne VOCs shaped the microbial communities, enriching potential VOC-utilizing bacteria (especially Nevskiaceae and Patulibacteraceae) in the irrigation water, where much of the VOC degradation capacity of the biofiltration systems resided. These results clearly show the benefits of active air circulation and optimized growth media in modern green wall systems. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  11. Aromatic chemicals by iron-catalyzed hydrotreatment of lignin pyrolysis vapor.

    Science.gov (United States)

    Olcese, Roberto Nicolas; Lardier, George; Bettahar, Mohammed; Ghanbaja, Jaafar; Fontana, Sébastien; Carré, Vincent; Aubriet, Frédéric; Petitjean, Dominique; Dufour, Anthony

    2013-08-01

    Lignin is a potential renewable material for the production of bio-sourced aromatic chemicals. We present the first hydrotreatment of lignin pyrolysis vapors, before any condensation, using inexpensive and sustainable iron-silica (Fe/SiO2 ) and iron-activated carbon (Fe/AC) catalysts. Lignin pyrolysis was conducted in a tubular reactor and vapors were injected in a fixed bed of catalysts (673 K, 1 bar) with stacks to investigate the profile of coke deposit. More than 170 GC-analyzable compounds were identified by GCxGC (heart cutting)/flame ionization detector mass spectrometry. Lignin oligomers were analyzed by very high resolution mass spectrometry, called the "petroleomic" method. They are trapped by the catalytic fixed bed and, in particular, by the AC. The catalysts showed a good selectivity for the hydrodeoxygenation of real lignin vapors to benzene, toluene, xylenes, phenol, cresols, and alkyl phenols. The spent catalysts were characterized by temperature-programmed oxidation, transmission electron microscopy (TEM), and N2 sorption. Micropores in the Fe/AC catalyst are completely plugged by coke deposits, whereas the mesoporous structure of Fe/SiO2 is unaffected. TEM images reveal two different types of coke deposit: 1) catalytic coke deposited in the vicinity of iron particles and 2) thermal coke (carbonaceous particles ≈1 μm in diameter) formed from the gas-phase growth of lignin oligomers. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Apparatus for chemical synthesis

    Science.gov (United States)

    Kong, Peter C [Idaho Falls, ID; Herring, J Stephen [Idaho Falls, ID; Grandy, Jon D [Idaho Falls, ID

    2011-05-10

    A method and apparatus for forming a chemical hydride is described and which includes a pseudo-plasma-electrolysis reactor which is operable to receive a solution capable of forming a chemical hydride and which further includes a cathode and a movable anode, and wherein the anode is moved into and out of fluidic, ohmic electrical contact with the solution capable of forming a chemical hydride and which further, when energized produces an oxygen plasma which facilitates the formation of a chemical hydride in the solution.

  13. Introduction to chemical kinetics

    CERN Document Server

    Soustelle, Michel

    2013-01-01

    This book is a progressive presentation of kinetics of the chemical reactions. It provides complete coverage of the domain of chemical kinetics, which is necessary for the various future users in the fields of Chemistry, Physical Chemistry, Materials Science, Chemical Engineering, Macromolecular Chemistry and Combustion. It will help them to understand the most sophisticated knowledge of their future job area. Over 15 chapters, this book present the fundamentals of chemical kinetics, its relations with reaction mechanisms and kinetic properties. Two chapters are then devoted to experimental re

  14. Chemical dependence - resources

    Science.gov (United States)

    Substance use - resources, Drug abuse - resources; Resources - chemical dependence ... are a good resource for information on drug dependence: National Council on Alcoholism and Drug Dependence -- ncadd. ...

  15. Laboratory of Chemical Physics

    Data.gov (United States)

    Federal Laboratory Consortium — Current research in the Laboratory of Chemical Physics is primarily concerned with experimental, theoretical, and computational problems in the structure, dynamics,...

  16. Analogies Between Digital Radio and Chemical Orthogonality as a Method for Enhanced Analysis of Molecular Recognition Events

    Directory of Open Access Journals (Sweden)

    Sang-Hun Lee

    2008-02-01

    Full Text Available Acoustic wave biosensors are a real-time, label-free biosensor technology, which have been exploited for the detection of proteins and cells. One of the conventional biosensor approaches involves the immobilization of a monolayer of antibodies onto the surface of the acoustic wave device for the detection of a specific analyte. The method described within includes at least two immobilizations of two different antibodies onto the surfaces of two separate acoustic wave devices for the detection of several analogous analytes. The chemical specificity of the molecular recognition event is achieved by virtue of the extremely high (nM to pM binding affinity between the antibody and its antigen. In a standard ELISA (Enzyme-Linked ImmunoSorbent Assay test, there are multiple steps and the end result is a measure of what is bound so tightly that it does not wash away easily. The fact that this “gold standard” is very much not real time, masks the dance that is the molecular recognition event. X-Ray Crystallographer, Ian Wilson, demonstrated more than a decade ago that antibodies undergo conformational change during a binding event[1, 2]. Further, it is known in the arena of immunochemistry that some antibodies exhibit significant cross-reactivity and this is widely termed antibody promiscuity. A third piece of the puzzle that we will exploit in our system of acoustic wave biosensors is the notion of chemical orthogonality. These three biochemical constructs, the dance, antibody promiscuity and chemical orthogonality will be combined in this paper with the notions of Int. J. Mol. Sci. 2008, 9 155 in-phase (I and quadrature (Q signals from digital radio to manifest an approach to molecular recognition that allows a level of discrimination and analysis unobtainable without the aggregate. As an example we present experimental data on the detection of TNT, RDX, C4, ammonium nitrate and musk oil from a system of antibody-coated acoustic

  17. Densities, Viscosities and Related Properties for Binary Mixtures of Sulfolane + p-Xylene, Sulfolane + Ethylbenzene in the Temperature Range from 303.15 K to 353.15 K%二元混合物环丁酚和对二甲苯、乙苯在温度范围为303.15-353.15K下的密度、黏度及其相关性质

    Institute of Scientific and Technical Information of China (English)

    杨长生; 马沛生; 周清

    2004-01-01

    Densities and viscosities of the binary systems of sulfolane + ethylbenzene, sulfolane + p-xylene have been experimentally determined in temperature interval 303.15-353.15 K and at atmospheric pressure for the whole composition range. The excess molar volumes and viscosity deviations were computed. The computed quantities have been fitted to Redlich-Kister equation. Excess molar volumes and viscosity deviation show a systematic change with increasing temperature. Two mixtures exhibit negative excess volumes with a minimum which occurs approximately at x = 0.5. The effect of the size, shape and interaction of components on excess molar volumes and viscosity deviations is discussed.

  18. Biobased chemicals from polyhydroxybutyrate

    NARCIS (Netherlands)

    Spekreijse, Jurjen

    2016-01-01

    Currently, most chemicals and materials are obtained from fossil resources. After use, these chemicals and materials are converted to CO2. As discussed in chapter 1, this causes a build-up of CO2 in the atmosphere, the main driving force of global warming. In order to reach a

  19. Studies in Chemical Dynamics

    International Nuclear Information System (INIS)

    Rabitz, Herschel; Ho, Tak-San

    2003-01-01

    This final report draws together the research carried from February, 1986 through January, 2003 concerning a series of topics in chemical dynamics. The specific areas of study include molecular collisions, chemical kinetics, data inversion to extract potential energy surfaces, and model reduction of complex kinetic systems

  20. Chemical Risk Assessment

    Science.gov (United States)

    This course is aimed at providing an overview of the fundamental guiding principles and general methods used in chemical risk assessment. Chemical risk assessment is a complex and ever-evolving process. These principles and methods have been organized by the National Research Cou...

  1. Chemical burn or reaction

    Science.gov (United States)

    Chemicals that touch skin can lead to a reaction on the skin, throughout the body, or both. ... leave the person alone and watch carefully for reactions affecting the entire body. Note: If a chemical gets into the eyes, the eyes should be ...

  2. Difficult Decisions: Chemical Warfare.

    Science.gov (United States)

    Slesnick, Irwin L.; Miller, John A.

    1988-01-01

    Gives the background history and chemistry of modern day chemical warfare from World War I to the present. Provides discussion questions to stimulate deeper thinking on the issue. Contains a discussion activity called "Can New Chemical Weapons Lead to Humane Warfare?" (CW)

  3. Multiple chemical sensitivity

    DEFF Research Database (Denmark)

    Tran, Marie Thi Dao; Arendt-Nielsen, Lars; Kupers, Ron

    2013-01-01

    BACKGROUND: Multiple Chemical Sensitivity (MCS) is a chronic condition characterized by recurrent, non-specific symptoms in response to chemically unrelated exposures in non-toxic concentrations. Although the pathophysiology of MCS remains unknown, central sensitization may be an important factor...

  4. Chemical Reactivity Test (CRT)

    Energy Technology Data Exchange (ETDEWEB)

    Zaka, F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-12-13

    The Chemical Reactivity Test (CRT) is used to determine the thermal stability of High Explosives (HEs) and chemical compatibility between (HEs) and alien materials. The CRT is one of the small-scale safety tests performed on HE at the High Explosives Applications Facility (HEAF).

  5. Chemical Equation Balancing.

    Science.gov (United States)

    Blakley, G. R.

    1982-01-01

    Reviews mathematical techniques for solving systems of homogeneous linear equations and demonstrates that the algebraic method of balancing chemical equations is a matter of solving a system of homogeneous linear equations. FORTRAN programs using this matrix method to chemical equation balancing are available from the author. (JN)

  6. Evaluation of semi-generic PBTK modeling for emergency risk assessment after acute inhalation exposure to volatile hazardous chemicals.

    Science.gov (United States)

    Olie, J Daniël N; Bessems, Jos G; Clewell, Harvey J; Meulenbelt, Jan; Hunault, Claudine C

    2015-08-01

    Physiologically Based Toxicokinetic Models (PBTK) may facilitate emergency risk assessment after chemical incidents with inhalation exposure, but they are rarely used due to their relative complexity and skill requirements. We aimed to tackle this problem by evaluating a semi-generic PBTK model built in MS Excel for nine chemicals that are widely-used and often released in a chemical incident. The semi-generic PBTK model was used to predict blood concentration-time curves using inhalation exposure scenarios from human volunteer studies, case reports and hypothetical exposures at Emergency Response Planning Guideline, Level 3 (ERPG-3) levels.(2) Predictions using this model were compared with measured blood concentrations from volunteer studies or case reports, as well as blood concentrations predicted by chemical-specific models. The performances of the semi-generic model were evaluated on biological rationale, accuracy, and ease of use and range of application. Our results indicate that the semi-generic model can be easily used to predict blood levels for eight out of nine parent chemicals (dichloromethane, benzene, xylene, styrene, toluene, isopropanol trichloroethylene and tetrachloroethylene). However, for methanol, 2-propanol and dichloromethane the semi-generic model could not cope with the endogenous production of methanol and of acetone (being a metabolite of 2-propanol) nor could it simulate the formation of HbCO, which is one of the toxic end-points of dichloromethane. The model is easy and intuitive to use by people who are not so familiar with toxicokinetic models. A semi-generic PBTK modeling approach can be used as a 'quick-and-dirty' method to get a crude estimate of the exposure dose. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Chemical evolution of galaxies

    CERN Document Server

    Matteucci, Francesca

    2012-01-01

    The term “chemical evolution of galaxies” refers to the evolution of abundances of chemical species in galaxies, which is due to nuclear processes occurring in stars and to gas flows into and out of galaxies. This book deals with the chemical evolution of galaxies of all morphological types (ellipticals, spirals and irregulars) and stresses the importance of the star formation histories in determining the properties of stellar populations in different galaxies. The topic is approached in a didactical and logical manner via galaxy evolution models which are compared with observational results obtained in the last two decades: The reader is given an introduction to the concept of chemical abundances and learns about the main stellar populations in our Galaxy as well as about the classification of galaxy types and their main observables. In the core of the book, the construction and solution of chemical evolution models are discussed in detail, followed by descriptions and interpretations of observations of ...

  8. Chemical Product Design

    DEFF Research Database (Denmark)

    Gani, Rafiqul

    2004-01-01

    This paper highlights for a class of chemical products, the design process, their design with respect to the important issues, the need for appropriate tools and finally, lists some of the challenges and opportunities for the process systems engineering (PSE)/computer-aided process engineering...... (CAPE) community. The chemical products considered belong to the following types: chemical/biochemical/agrochemical products, coatings and solvents, food (nutraceuticals), HIM (household, industrial and institutional), personal care, pharmaceuticals and drugs. The challenges and opportunities...... are highlighted in terms of the needs for multi-level modeling with emphasis on property models that are suitable for computer-aided applications, flexible solution strategies that are able to solve a large range of chemical product design problems and finally, a systems chemical product design framework...

  9. Chemical-induced Vitiligo

    Science.gov (United States)

    Harris, John E.

    2016-01-01

    Synopsis Chemical-induced depigmentation of the skin has been recognized for over 75 years, first as an occupational hazard but then extending to those using household commercial products as common as hair dyes. Since their discovery, these chemicals have been used therapeutically in patients with severe vitiligo to depigment their remaining skin and improve their appearance. The importance of recognizing this phenomenon was highlighted during an outbreak of vitiligo in Japan during the summer of 2013, when over 16,000 users of a new skin lightening cosmetic cream developed skin depigmentation at the site of contact with the cream and many in remote areas as well. Depigmenting chemicals appear to be analogs of the amino acid tyrosine that disrupt melanogenesis and result in autoimmunity and melanocyte destruction. Because chemical-induced depigmentation is clinically and histologically indistinguishable from non-chemically induced vitiligo, and because these chemicals appear to induce melanocyte autoimmunity, this phenomenon should be known as “chemical-induced vitiligo”, rather than less accurate terms that have been previously used. PMID:28317525

  10. Chemical process hazards analysis

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-02-01

    The Office of Worker Health and Safety (EH-5) under the Assistant Secretary for the Environment, Safety and Health of the US Department (DOE) has published two handbooks for use by DOE contractors managing facilities and processes covered by the Occupational Safety and Health Administration (OSHA) Rule for Process Safety Management of Highly Hazardous Chemicals (29 CFR 1910.119), herein referred to as the PSM Rule. The PSM Rule contains an integrated set of chemical process safety management elements designed to prevent chemical releases that can lead to catastrophic fires, explosions, or toxic exposures. The purpose of the two handbooks, ``Process Safety Management for Highly Hazardous Chemicals`` and ``Chemical Process Hazards Analysis,`` is to facilitate implementation of the provisions of the PSM Rule within the DOE. The purpose of this handbook ``Chemical Process Hazards Analysis,`` is to facilitate, within the DOE, the performance of chemical process hazards analyses (PrHAs) as required under the PSM Rule. It provides basic information for the performance of PrHAs, and should not be considered a complete resource on PrHA methods. Likewise, to determine if a facility is covered by the PSM rule, the reader should refer to the handbook, ``Process Safety Management for Highly Hazardous Chemicals`` (DOE- HDBK-1101-96). Promulgation of the PSM Rule has heightened the awareness of chemical safety management issues within the DOE. This handbook is intended for use by DOE facilities and processes covered by the PSM rule to facilitate contractor implementation of the PrHA element of the PSM Rule. However, contractors whose facilities and processes not covered by the PSM Rule may also use this handbook as a basis for conducting process hazards analyses as part of their good management practices. This handbook explains the minimum requirements for PrHAs outlined in the PSM Rule. Nowhere have requirements been added beyond what is specifically required by the rule.

  11. Biobased chemicals from polyhydroxybutyrate

    OpenAIRE

    Spekreijse, Jurjen

    2016-01-01

    Currently, most chemicals and materials are obtained from fossil resources. After use, these chemicals and materials are converted to CO2. As discussed in chapter 1, this causes a build-up of CO2 in the atmosphere, the main driving force of global warming. In order to reach a sustainable system, biomass could be used as a resource for chemicals and materials instead. A biorefinery approach, where all parts of biomass are used to its full potential is essential. Taking this into consideration,...

  12. Chemical ecology of fungi.

    Science.gov (United States)

    Spiteller, Peter

    2015-07-01

    Fungi are widespread in nature and have conquered nearly every ecological niche. Fungi occur not only in terrestrial but also in freshwater and marine environments. Moreover, fungi are known as a rich source of secondary metabolites. Despite these facts, the ecological role of many of these metabolites is still unknown and the chemical ecology of fungi has not been investigated systematically so far. This review intends to present examples of the various chemical interactions of fungi with other fungi, plants, bacteria and animals and to give an overview of the current knowledge of fungal chemical ecology.

  13. Chemical equilibration of antihyperons

    International Nuclear Information System (INIS)

    Greiner, C.

    2002-01-01

    Rapid chemical equilibration of antihyperons by means of the interplay between strong annihilation on baryons and the corresponding backreactions of multi-mesonic (fusion-type) processes in the later, hadronic stage of an ultrarelativistic heavy ion collision will be discussed. Explicit rate calculations for a dynamical setup are presented. At maximum SPS energies yields of each antihyperon specie are obtained which are consistent with chemical saturated populations of T∼150-160 MeV. The proposed picture supports dynamically the popular chemical freeze-out parameters extracted within thermal models. (orig.)

  14. Chemical warfare agents

    Directory of Open Access Journals (Sweden)

    Vijayaraghavan R

    2010-01-01

    Full Text Available Among the Weapons of Mass Destruction, chemical warfare (CW is probably one of the most brutal created by mankind in comparison with biological and nuclear warfare. Chemical weapons are inexpensive and are relatively easy to produce, even by small terrorist groups, to create mass casualties with small quantities. The characteristics of various CW agents, general information relevant to current physical as well as medical protection methods, detection equipment available and decontamination techniques are discussed in this review article. A brief note on Chemical Weapons Convention is also provided.

  15. Chemical warfare agents

    Science.gov (United States)

    Ganesan, K.; Raza, S. K.; Vijayaraghavan, R.

    2010-01-01

    Among the Weapons of Mass Destruction, chemical warfare (CW) is probably one of the most brutal created by mankind in comparison with biological and nuclear warfare. Chemical weapons are inexpensive and are relatively easy to produce, even by small terrorist groups, to create mass casualties with small quantities. The characteristics of various CW agents, general information relevant to current physical as well as medical protection methods, detection equipment available and decontamination techniques are discussed in this review article. A brief note on Chemical Weapons Convention is also provided. PMID:21829312

  16. Advanced Chemical Propulsion

    Science.gov (United States)

    Bai, S. Don

    2000-01-01

    Design, propellant selection, and launch assistance for advanced chemical propulsion system is discussed. Topics discussed include: rocket design, advance fuel and high energy density materials, launch assist, and criteria for fuel selection.

  17. Elements of chemical thermodynamics

    CERN Document Server

    Nash, Leonard K

    2005-01-01

    This survey of purely thermal data in calculating the position of equilibrium in a chemical reaction highlights the physical content of thermodynamics, as distinct from purely mathematical aspects. 1970 edition.

  18. TSCA Chemical Substance Inventory

    Science.gov (United States)

    Section 8 (b) of the Toxic Substances Control Act (TSCA) requires EPA to compile, keep current, and publish a list of each chemical substance that is manufactured or processed in the United States for TSCA uses.

  19. Chemical Engineering at NASA

    Science.gov (United States)

    Collins, Jacob

    2008-01-01

    This viewgraph presentation is a review of the career paths for chemicals engineer at NASA (specifically NASA Johnson Space Center.) The author uses his personal experience and history as an example of the possible career options.

  20. Aerosol chemical physics

    International Nuclear Information System (INIS)

    Marlow, W.H.

    1982-01-01

    A classification of the research fields in the chemical physics of aerosol microparticles is given. The emphasis lies on the microphysics of isolated particles and clusters and on physical transformations and thermodynamics. (LDN)

  1. Biotechnology for renewable chemicals

    DEFF Research Database (Denmark)

    Borodina, Irina; Kildegaard, Kanchana Rueksomtawin; Jensen, Niels Bjerg

    2014-01-01

    The majority of the industrial organic chemicals are derived from fossil sources. With the oil and gas resources becoming limiting, biotechnology offers a sustainable alternative for production ofchemicals from renewable feedstocks. Yeast is an attractive cell factory forsustainable production...

  2. Chemically stabilized soils.

    Science.gov (United States)

    2009-12-01

    The objective of this study was to conduct laboratory evaluations to quantify the effects of compaction and moisture conditions on the strength of chemically treated soils typical utilized in pavement construction in Mississippi.

  3. Graphene Chemical Sensor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Develop graphene based miniaturized chemical sensors that will be able to detect gaseous and volatile molecules with high sensitivity, good reproducibility and wide...

  4. Graphene Chemical Sensor

    Data.gov (United States)

    National Aeronautics and Space Administration — Develop graphene based miniaturized chemical sensors that will be able to detect gaseous and volatile molecules with high sensitivity, good reproducibility and wide...

  5. Chemical Speciation - General Information

    Science.gov (United States)

    This page includes general information about the Chemical Speciation Network that is not covered on the main page. Commonly visited documents, including calendars, site lists, and historical files for the program are listed here

  6. Chemical Data Access Tool

    Data.gov (United States)

    U.S. Environmental Protection Agency — This tool is intended to aid individuals interested in learning more about chemicals that are manufactured or imported into the United States. Health and safety...

  7. Chemical evolution and life

    Directory of Open Access Journals (Sweden)

    Malaterre Christophe

    2015-01-01

    Full Text Available In research on the origins of life, the concept of “chemical evolution” aims at explaining the transition from non-living matter to living matter. There is however strong disagreement when it comes to defining this concept more precisely, and in particular with reference to a chemical form of Darwinian evolution: for some, chemical evolution is nothing but Darwinian evolution applied to chemical systems before life appeared; yet, for others, it is the type of evolution that happened before natural selection took place, the latter being the birthmark of living systems. In this contribution, I review the arguments defended by each side and show how both views presuppose a dichotomous definition of “life”.

  8. Chemical warfare agents.

    Science.gov (United States)

    Kuca, Kamil; Pohanka, Miroslav

    2010-01-01

    Chemical warfare agents are compounds of different chemical structures. Simple molecules such as chlorine as well as complex structures such as ricin belong to this group. Nerve agents, vesicants, incapacitating agents, blood agents, lung-damaging agents, riot-control agents and several toxins are among chemical warfare agents. Although the use of these compounds is strictly prohibited, the possible misuse by terrorist groups is a reality nowadays. Owing to this fact, knowledge of the basic properties of these substances is of a high importance. This chapter briefly introduces the separate groups of chemical warfare agents together with their members and the potential therapy that should be applied in case someone is intoxicated by these agents.

  9. Chemical radwaste solidification processes

    International Nuclear Information System (INIS)

    Malloy, C.W.

    1979-01-01

    Some of these processes and their problems are briefly reviewed: early cement systems; urea-formaldehyde; Dow solidification process; low-viscosity chemical agents (POLYPAC); and water-extensible polyester. 9 refs

  10. Chemical allergy in humans

    DEFF Research Database (Denmark)

    Kimber, Ian; Basketter, David A; Thyssen, Jacob P

    2014-01-01

    Abstract There is considerable interest in the immunobiological processes through which the development of allergic sensitization to chemicals is initiated and orchestrated. One of the most intriguing issues is the basis for the elicitation by chemical sensitizers of different forms of allergic...... reaction; that is, allergic contact dermatitis or sensitization of the respiratory tract associated with occupational asthma. Studies in rodents have revealed that differential forms of allergic sensitization to chemicals are, in large part at least, a function of the selective development of discrete...... functional sub-populations of CD4(+) and CD8(+) T-lymphocytes. Evidence for a similar association of chemical allergy in humans with discrete T-lymphocyte populations is, however, limited. It is of some interest, therefore, that two recent articles from different teams of investigators have shed new light...

  11. Chemical defences against herbivores

    DEFF Research Database (Denmark)

    Pavia, Henrik; Baumgartner, Finn; Cervin, Gunnar

    2012-01-01

    This chapter focuses on the recent and emerging research involving chemical defences against herbivory in aquatic primary producers. It provides an overview of plant chemical defence theories and highlights recent research on aquatic primary producers addressing a number of aspects...... of these theories, concluding with new chemical approaches to tackle the questions and suggestions for future research directions. It explains that aquatic primary producers are a taxonomically and functionally diverse group of organisms that includes macroalgae, microalgae, and vascular plants. It also states...... that despite the fact that aquatic primary producers constitute a large and diverse group of organisms that vary in their evolutionary histories, selection for chemical defences to resist or reduce grazing are commonplace across the phylogenetic boundaries....

  12. Chemical agent recoveries

    Data.gov (United States)

    U.S. Environmental Protection Agency — Dataset shows the calculation of reported decontamination efficacies from the raw data (i.e., measured amount of chemical recovered from test coupons and positive...

  13. Chemical composition of Chinese palm fruit and chemical properties ...

    African Journals Online (AJOL)

    ... chemical properties and could be used as edible oils and for industrial applications. ... on it, which can provide useful information for Chinese oil palm industry. Key words: Chemical composition, palm fruit, palm oil, palm kernel oil, chemical ...

  14. Computational Systems Chemical Biology

    OpenAIRE

    Oprea, Tudor I.; May, Elebeoba E.; Leitão, Andrei; Tropsha, Alexander

    2011-01-01

    There is a critical need for improving the level of chemistry awareness in systems biology. The data and information related to modulation of genes and proteins by small molecules continue to accumulate at the same time as simulation tools in systems biology and whole body physiologically-based pharmacokinetics (PBPK) continue to evolve. We called this emerging area at the interface between chemical biology and systems biology systems chemical biology, SCB (Oprea et al., 2007).

  15. Whole system chemical geothermometry

    International Nuclear Information System (INIS)

    Pang Zhonghe

    1999-01-01

    Chemical and isotopic geothermometers are equations or models based on temperature dependent chemical reactions or isotope equilibrium fractionation reactions from which equilibrium temperatures of these reactions can be calculated. The major drawback of all the conventional geothermometry methods lies in their incapability on making a judgement on the equilibrium status of the studied systems. This review will focus on two of recent approaches in this field. Zhangzhou Geothermal Field in SE China will be used as an example to demonstrate the applications

  16. Risk from environmental chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Somers, E [Environmental Health Directorate, Health Protection Branch, Health and Welfare Canada, Ontario

    1982-01-01

    The elements of risk assessment, namely risk identification, risk estimation, risk evaluation and risk management, are described with respect to the control of environmental chemicals. The methodology of risk estimation is outlined and examples given of its application to regulatory decision-making for a number of chemicals in Canada. Finally, the extent and limitations of the process of risk evaluation are considered together with the need to recognize the importance of the public's perception of the level of risk.

  17. Chemical evolution of galaxies

    International Nuclear Information System (INIS)

    Matteucci, F.; Consiglio Nazionale delle Ricerche, Frascati

    1989-01-01

    In principle, a good model of galactic chemical evolution should fulfil the majority of well established observational constraints. The goal of this paper is to review the observational data together with the existing chemical evolution models for the Milky Way (the disk), Blue Compact and Elliptical galaxies and to show how well the models can account for the observations. Some open problems and future prospects are also discussed. (author)

  18. Chemical effects of radiation

    International Nuclear Information System (INIS)

    Philips, G.O.

    1986-01-01

    Ionizing radiations initiate chemical changes in materials because of the high energy of their quanta. In water, highly reactive free radicals are produced which can initiate secondary changes of solutes, and in chemical of biological molecules in contact with the water. Free radicals can also be directly produced in irradiated medical products. Their fate can be identified and the molecular basis of radiation inactivation clarified. Methods have now been developed to protect and minimise such radiation damage. (author)

  19. Nuclear chemical engineering

    International Nuclear Information System (INIS)

    Lee, Geon Jae; Shin, Young Jun

    1989-08-01

    The contents of this book are introduction of chemical engineering and related chemistry on an atomic reactor, foundation of the chemistry nuclear chemical engineering, theory on nuclear engineering, the cycle of uranium and nuclear fuel, a product of nuclear division, nuclear reprocessing, management of spent fuel separation of radioisotope, materials of an atomic reactor, technology and chemistry related water in atomic reactors and utilization of radioisotope and radiation. This book has the exercises and reference books for the each chapter.

  20. Ultrasound in chemical processes

    International Nuclear Information System (INIS)

    Baig, S.; Farooq, R.; Malik, A.H.

    2009-01-01

    The use of ultrasound to promote chemical reactions or sono chemistry is a field of chemistry which involves the process of acoustic cavitations i.e. the collapse of microscopic bubbles in liquid. There are two essential components for the application of sono chemistry, a liquid medium and a source of high-energy vibrations. The liquid medium is necessary because sono chemistry is driven by acoustic cavitations that can only occur in liquids. The source of the vibrational energy is the transducer. The chemical effects of ultrasound include the enhancement of reaction rates at ambient temperatures and striking advancements in stoichiometric and catalytic reactions In some cases, ultrasonic irradiation can increase reactivities by nearly million fold. The ultrasound has large number of applications not only in emending old chemical processes but also in developing new synthetic strategies. Ultrasound enhances all chemical and physical processes e.g., crystallization, vitamin synthesis, preparation of catalysts, dissolution of chemicals, organometallic reactions, electrochemical processes, etc. High-power ultrasonics is a new powerful technology that is not only safe and environmentally friendly in its application but is also efficient and economical. It can be applied to existing processes to eliminate the need for chemicals and/or heat application in a variety of industrial processes. (author)

  1. Environmental/chemical thesaurus

    International Nuclear Information System (INIS)

    Shriner, C.R.; Dailey, N.S.; Jordan, A.C.; Miller, K.C.; Owens, E.T.; Rickert, L.W.

    1978-06-01

    The Environmental/Chemical Thesaurus approaches scientific language control problems from a multidisciplinary view. The Environmental/Biomedical Terminology Index (EBTI) was used as a base for the present thesaurus. The Environmental/Chemical Thesaurus, funded by the Environmental Protection Agency, used as its source of new terms those major terms found in 13 Environmental Protection Agency data bases. The scope of this thesaurus includes not only environmental and biomedical sciences, but also the physical sciences with emphasis placed on chemistry. Specific chemical compounds are not included; only classes of chemicals are given. To adhere to this level of classification, drugs and pesticides are identified by class rather than by specific chemical name. An attempt was also made to expand the areas of sociology and economics. Terminology dealing with law, demography, and geography was expanded. Proper names of languages and races were excluded. Geographic terms were expanded to include proper names for oceans, continents, major lakes, rivers, and islands. Political divisions were added to allow for proper names of countries and states. With such a broad scope, terminology for specific sciences does not provide for indexing to the lowest levels in plant, animal, or chemical classifications

  2. Environmental/chemical thesaurus

    Energy Technology Data Exchange (ETDEWEB)

    Shriner, C.R.; Dailey, N.S.; Jordan, A.C.; Miller, K.C.; Owens, E.T.; Rickert, L.W.

    1978-06-01

    The Environmental/Chemical Thesaurus approaches scientific language control problems from a multidisciplinary view. The Environmental/Biomedical Terminology Index (EBTI) was used as a base for the present thesaurus. The Environmental/Chemical Thesaurus, funded by the Environmental Protection Agency, used as its source of new terms those major terms found in 13 Environmental Protection Agency data bases. The scope of this thesaurus includes not only environmental and biomedical sciences, but also the physical sciences with emphasis placed on chemistry. Specific chemical compounds are not included; only classes of chemicals are given. To adhere to this level of classification, drugs and pesticides are identified by class rather than by specific chemical name. An attempt was also made to expand the areas of sociology and economics. Terminology dealing with law, demography, and geography was expanded. Proper names of languages and races were excluded. Geographic terms were expanded to include proper names for oceans, continents, major lakes, rivers, and islands. Political divisions were added to allow for proper names of countries and states. With such a broad scope, terminology for specific sciences does not provide for indexing to the lowest levels in plant, animal, or chemical classifications.

  3. Nuclear and Chemical Weapons and Materiel: Chemical Surety

    National Research Council Canada - National Science Library

    2001-01-01

    .... It has been revised to update responsibilities, Personnel Reliability Program (PRP) procedures, transportation policies, chemical event notification, chemical accident or incident response and assistance (CAIRA...

  4. Variations in amounts and potential sources of volatile organic chemicals in new cars

    International Nuclear Information System (INIS)

    Chien, Y.-C.

    2007-01-01

    This study examines inter-brand, intra-brand and intra-model variations in volatile organic chemical (VOC) levels inside new cars. The effect of temperature on interior VOC levels was examined using model automobiles with and without the air-conditioning running. Potential sources of VOC were assessed by comparing VOC levels with two interior trims (leather and fabric) and by analyzing VOC emissions from various interior components. Five brands of new car, both domestic and imported, were tested. Twelve targeted VOCs were collected on solid sorbents and analyzed using thermal desorption and GC/FID. VOCs from interior parts and adhesives were identified using solid phase micro-extraction (SPME) coupled with GC/MS. The VOC concentrations varied markedly among brands and within models, and individual VOC levels ranged from below the detection limit (a few μg per cubic meter) to thousands of μg per cubic meter. The intra-model variability (mean, 47%) in the VOC levels was approximately 50% that within each brand (mean, 95%). Although interior trim levels affected VOC levels, the effects differed among brands. Reduction of the cabin temperature reduced most VOC levels, but the impact was not statistically significant. Screening tests for VOCs from interior parts revealed that butylated hydroxytoluene (BHT), a common anti-oxidant, was the most common chemical. Long-chain aliphatic hydrocarbons, particularly C14-C17, were identified in most grease (lubricant) samples, and toluene and xylenes were ubiquitously present in adhesive samples. Process-related compounds, such as plasticizer, were also identified in interior parts. In-cabin VOC levels varied significantly among makes/models and interior trims. Concerned consumers should purchase older new cars from manufacturers since VOC levels inside car cabins normally declines over time. Improved processes or materials with lower VOC emission potential should be used to minimize in-cabin VOC sources for new cars

  5. An improvement of LLNA:DA to assess the skin sensitization potential of chemicals.

    Science.gov (United States)

    Zhang, Hongwei; Shi, Ying; Wang, Chao; Zhao, Kangfeng; Zhang, Shaoping; Wei, Lan; Dong, Li; Gu, Wen; Xu, Yongjun; Ruan, Hongjie; Zhi, Hong; Yang, Xiaoyan

    2017-01-01

    We developed a modified local lymph node assay based on ATP (LLNA:DA), termed the Two-Stage LLNA:DA, to further reduce the animal numbers in the identification of sensitizers. In the Two-Stage LLNA:DA procedure, 13 chemicals ranging from non-sensitizers to extreme sensitizers were selected. The first stage used reduced LLNA:DA (rLLNA:DA) to screen out sensitive chemicals. The second stage used LLNA:DA based on OECD 442 (A) to classify those potential sensitizers screened out in the first stage. In the first stage, the SIs of the methyl methacrylate, salicylic acid, methyl salicylate, ethyl salicylate, isopropanol and propanediol were below 1.8 and need not to be tested in the second step. Others continued to be tested by LLNA:DA. In the second stage, sodium lauryl sulphate and xylene were classified as weak sensitizers. a-hexyl cinnamic aldehyde and eugenol were moderate sensitizers. Benzalkonium chloride and glyoxal were strong sensitizers, and phthalic anhydride was an extreme sensitizer. The 9/9, 11/12, 10/11, and 8/13 (positive or negative only) categories of the Two-Stage LLNA:DA were consistent with those from the other methods (LLNA, LLNA:DA, GPMT/BT and HMT/HPTA), suggesting that Two-Stage LLNA:DA have a high coincidence rate with reported data. In conclusion, The Two-Stage LLNA:DA is in line with the "3R" rules, and can be a modification of LLNA:DA but needs more study.

  6. Islamic State and Chemical Weapons

    Directory of Open Access Journals (Sweden)

    Lukáš Rafay

    2016-09-01

    Full Text Available The article deals with topic of Islamic State and chemical weapons. The issue is analysed in three dimensions: origin of used chemical weapons and possibility of independent production; known chemical attacks and tactical regularities in their execution; and traits of future chemical terrorist attacks. By providing a thorough examination of the problem, the article aims at predicting the future development of the group’s chemical program as well as describing any prospective chemical terrorist attacks in Europe

  7. Chemical kinetics of gas reactions

    CERN Document Server

    Kondrat'Ev, V N

    2013-01-01

    Chemical Kinetics of Gas Reactions explores the advances in gas kinetics and thermal, photochemical, electrical discharge, and radiation chemical reactions. This book is composed of 10 chapters, and begins with the presentation of general kinetic rules for simple and complex chemical reactions. The next chapters deal with the experimental methods for evaluating chemical reaction mechanisms and some theories of elementary chemical processes. These topics are followed by discussions on certain class of chemical reactions, including unimolecular, bimolecular, and termolecular reactions. The rema

  8. Current Chemical Risk Management Activities

    Science.gov (United States)

    EPA's existing chemicals programs address pollution prevention, risk assessment, hazard and exposure assessment and/or characterization, and risk management for chemicals substances in commercial use.

  9. Accessing and using chemical databases

    DEFF Research Database (Denmark)

    Nikolov, Nikolai Georgiev; Pavlov, Todor; Niemelä, Jay Russell

    2013-01-01

    Computer-based representation of chemicals makes it possible to organize data in chemical databases-collections of chemical structures and associated properties. Databases are widely used wherever efficient processing of chemical information is needed, including search, storage, retrieval......, and dissemination. Structure and functionality of chemical databases are considered. The typical kinds of information found in a chemical database are considered-identification, structural, and associated data. Functionality of chemical databases is presented, with examples of search and access types. More details...... are included about the OASIS database and platform and the Danish (Q)SAR Database online. Various types of chemical database resources are discussed, together with a list of examples....

  10. Chemical Equilibrium And Transport (CET)

    Science.gov (United States)

    Mcbride, B. J.

    1991-01-01

    Powerful, machine-independent program calculates theoretical thermodynamic properties of chemical systems. Aids in design of compressors, turbines, engines, heat exchangers, and chemical processing equipment.

  11. Chemical evolutionary games.

    Science.gov (United States)

    Aristotelous, Andreas C; Durrett, Richard

    2014-05-01

    Inspired by the use of hybrid cellular automata in modeling cancer, we introduce a generalization of evolutionary games in which cells produce and absorb chemicals, and the chemical concentrations dictate the death rates of cells and their fitnesses. Our long term aim is to understand how the details of the interactions in a system with n species and m chemicals translate into the qualitative behavior of the system. Here, we study two simple 2×2 games with two chemicals and revisit the two and three species versions of the one chemical colicin system studied earlier by Durrett and Levin (1997). We find that in the 2×2 examples, the behavior of our new spatial model can be predicted from that of the mean field differential equation using ideas of Durrett and Levin (1994). However, in the three species colicin model, the system with diffusion does not have the coexistence which occurs in the lattices model in which sites interact with only their nearest neighbors. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Applied chemical engineering thermodynamics

    CERN Document Server

    Tassios, Dimitrios P

    1993-01-01

    Applied Chemical Engineering Thermodynamics provides the undergraduate and graduate student of chemical engineering with the basic knowledge, the methodology and the references he needs to apply it in industrial practice. Thus, in addition to the classical topics of the laws of thermodynamics,pure component and mixture thermodynamic properties as well as phase and chemical equilibria the reader will find: - history of thermodynamics - energy conservation - internmolecular forces and molecular thermodynamics - cubic equations of state - statistical mechanics. A great number of calculated problems with solutions and an appendix with numerous tables of numbers of practical importance are extremely helpful for applied calculations. The computer programs on the included disk help the student to become familiar with the typical methods used in industry for volumetric and vapor-liquid equilibria calculations.

  13. Advanced Chemical Propulsion Study

    Science.gov (United States)

    Woodcock, Gordon; Byers, Dave; Alexander, Leslie A.; Krebsbach, Al

    2004-01-01

    A study was performed of advanced chemical propulsion technology application to space science (Code S) missions. The purpose was to begin the process of selecting chemical propulsion technology advancement activities that would provide greatest benefits to Code S missions. Several missions were selected from Code S planning data, and a range of advanced chemical propulsion options was analyzed to assess capabilities and benefits re these missions. Selected beneficial applications were found for higher-performing bipropellants, gelled propellants, and cryogenic propellants. Technology advancement recommendations included cryocoolers and small turbopump engines for cryogenic propellants; space storable propellants such as LOX-hydrazine; and advanced monopropellants. It was noted that fluorine-bearing oxidizers offer performance gains over more benign oxidizers. Potential benefits were observed for gelled propellants that could be allowed to freeze, then thawed for use.

  14. Nanotechnology for chemical engineers

    CERN Document Server

    Salaheldeen Elnashaie, Said; Hashemipour Rafsanjani, Hassan

    2015-01-01

    The book describes the basic principles of transforming nano-technology into nano-engineering with a particular focus on chemical engineering fundamentals. This book provides vital information about differences between descriptive technology and quantitative engineering for students as well as working professionals in various fields of nanotechnology. Besides chemical engineering principles, the fundamentals of nanotechnology are also covered along with detailed explanation of several specific nanoscale processes from chemical engineering point of view. This information is presented in form of practical examples and case studies that help the engineers and researchers to integrate the processes which can meet the commercial production. It is worth mentioning here that, the main challenge in nanostructure and nanodevices production is nowadays related to the economic point of view. The uniqueness of this book is a balance between important insights into the synthetic methods of nano-structures and nanomaterial...

  15. Rapid chemical separations

    CERN Document Server

    Trautmann, N

    1976-01-01

    A survey is given on the progress of fast chemical separation procedures during the last few years. Fast, discontinuous separation techniques are illustrated by a procedure for niobium. The use of such techniques for the chemical characterization of the heaviest known elements is described. Other rapid separation methods from aqueous solutions are summarized. The application of the high speed liquid chromatography to the separation of chemically similar elements is outlined. The use of the gas jet recoil transport method for nuclear reaction products and its combination with a continuous solvent extraction technique and with a thermochromatographic separation is presented. Different separation methods in the gas phase are briefly discussed and the attachment of a thermochromatographic technique to an on-line mass separator is shown. (45 refs).

  16. Chemical Inhibition of Autophagy

    DEFF Research Database (Denmark)

    Baek, Eric; Lin Kim, Che; Gyeom Kim, Mi

    2016-01-01

    Chinese hamster ovary (CHO) cells activate and undergo apoptosis and autophagy for various environmental stresses. Unlike apoptosis, studies on increasing the production of therapeutic proteins in CHO cells by targeting the autophagy pathway are limited. In order to identify the effects of chemical...... autophagy inhibitors on the specific productivity (qp), nine chemical inhibitors that had been reported to target three different phases of autophagy (metformin, dorsomorphin, resveratrol, and SP600125 against initiation and nucleation; 3-MA, wortmannin, and LY294002 against elongation, and chloroquine...... and bafilomycin A1 against autophagosome fusion) were used to treat three recombinant CHO (rCHO) cell lines: the Fc-fusion protein-producing DG44 (DG44-Fc) and DUKX-B11 (DUKX-Fc) and antibody-producing DG44 (DG44-Ab) cell lines. Among the nine chemical inhibitors tested, 3-MA, dorsomorphin, and SP600125...

  17. Chemical profiling of chemical warfare agents for forensic purposes

    NARCIS (Netherlands)

    Noort, D.; Reuver, L.P.J. de; Fidder, A.; Tromp, M.; Verschraagen, M.

    2010-01-01

    A program has been initiated towards the chemical profiling of chemical warfare agents, in order to support forensic investigations towards synthesis routes, production sites and suspect chemical suppliers. Within the first stage of the project various chemical warfare agents (VX, sulfur mustard,

  18. Principles of chemical kinetics

    CERN Document Server

    House, James E

    2007-01-01

    James House's revised Principles of Chemical Kinetics provides a clear and logical description of chemical kinetics in a manner unlike any other book of its kind. Clearly written with detailed derivations, the text allows students to move rapidly from theoretical concepts of rates of reaction to concrete applications. Unlike other texts, House presents a balanced treatment of kinetic reactions in gas, solution, and solid states. The entire text has been revised and includes many new sections and an additional chapter on applications of kinetics. The topics covered include quantitative rela

  19. Multiple Chemical Sensitivity

    DEFF Research Database (Denmark)

    Dantoft, Thomas Meinertz

    Multiple chemical sensitivity (MCS) is a chronic disorder characterized by reports of symptoms from various organ systems attributed by the individuals to exposure to common odors and airborne chemicals in doses far below those known to induce toxic effects. There exists a general lack of knowledge......, significantly reduced levels of IL-13 in the MCS group and no group differences in the allergen specific IgE measures. The differences were independent of factors such as sex, age, Body Mass Index, asthma, smoking, depression, anxiety and allergen-specific IgE. In conclusion, the study identified a distinct...

  20. Endocrine disrupting chemicals

    DEFF Research Database (Denmark)

    Mandrup, Karen

    chemical ethinyl estradiol, only. In studies on exposure to anti-androgens, other endpoints, such as nipple retention showed effects in male rats at dose levels where no effects were observed in male or female mammary glands orfemale external genitals. However, in studies on estrogenic chemicals, marked...... effects on prepubertal female rat mammary glands were observed at lower levels than those affecting other endpoints studied. CONCLUSION: The present findings in rats suggest that EDCs may affect mammary gland development in women and men, although risk assessment including comparison with exposure...

  1. The renewable chemicals industry

    DEFF Research Database (Denmark)

    Christensen, Claus H.; Rass-Hansen, J.; Marsden, Charlotte Clare

    2008-01-01

    per kilogram of desired product to illustrate in which processes the use of renewable resources lead to the most substantial reduction of CO2 emissions. The steps towards a renewable chemicals industry will most likely involve intimate integration of biocatalytic and conventional catalytic processes......The possibilities for establishing a renewable chemicals industry featuring renewable resources as the dominant feedstock rather than fossil resources are discussed in this Concept. Such use of biomass can potentially be interesting from both an economical and ecological perspective. Simple...

  2. An indoor chemical cocktail

    Science.gov (United States)

    Gligorovski, Sasho; Abbatt, Jonathan P. D.

    2018-02-01

    In the past 50 years, many of the contaminants and chemical transformations that occur in outdoor waters, soils, and air have been elucidated. However, the chemistry of the indoor environment in which we live most of the time—up to 90% in some societies—is not nearly as well studied. Recent work has highlighted the wealth of chemical transformations that occur indoors. This chemistry is associated with 3 of the top 10 risk factors for negative health outcomes globally: household air pollution from solid fuels, tobacco smoking, and ambient particulate matter pollution (1). Assessments of human exposure to indoor pollutants must take these reactive processes into consideration.

  3. Some Examples of Residence-Time Distribution Studies in Large-Scale Chemical Processes by Using Radiotracer Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Bullock, R. M.; Johnson, P.; Whiston, J. [Imperial Chemical Industries Ltd., Billingham, Co., Durham (United Kingdom)

    1967-06-15

    The application of radiotracers to determine flow patterns in chemical processes is discussed with particular reference to the derivation of design data from model reactors for translation to large-scale units, the study of operating efficiency and design attainment in established plant and the rapid identification of various types of process malfunction. The requirements governing the selection of tracers for various types of media are considered and an example is given of the testing of the behaviour of a typical tracer before use in a particular large-scale process operating at 250 atm and 200 Degree-Sign C. Information which may be derived from flow patterns is discussed including the determination of mixing parameters, gas hold-up in gas/liquid reactions and the detection of channelling and stagnant regions. Practical results and their interpretation are given in relation to an define hydroformylation reaction system, a process for the conversion of propylene to isopropanol, a moving bed catalyst system for the isomerization of xylenes and a three-stage gas-liquid reaction system. The use of mean residence-time data for the detection of leakage between reaction vessels and a heat interchanger system is given as an example of the identification of process malfunction. (author)

  4. Development of a detailed chemical mechanism (MCMv3.1 for the atmospheric oxidation of aromatic hydrocarbons

    Directory of Open Access Journals (Sweden)

    C. Bloss

    2005-01-01

    Full Text Available The Master Chemical Mechanism has been updated from MCMv3 to MCMv3.1 in order to take into account recent improvements in the understanding of aromatic photo-oxidation. Newly available kinetic and product data from the literature have been incorporated into the mechanism. In particular, the degradation mechanisms for hydroxyarenes have been revised following the observation of high yields of ring-retained products, and product studies of aromatic oxidation under relatively low NOx conditions have provided new information on the branching ratios to first generation products. Experiments have been carried out at the European Photoreactor (EUPHORE to investigate key subsets of the toluene system. These results have been used to test our understanding of toluene oxidation, and, where possible, refine the degradation mechanisms. The evaluation of MCMv3 and MCMv3.1 using data on benzene, toluene, p-xylene and 1,3,5-trimethylbenzene photosmog systems is described in a companion paper, and significant model shortcomings are identified. Ideas for additional modifications to the mechanisms, and for future experiments to further our knowledge of the details of aromatic photo-oxidation are discussed.

  5. Environmental Chemicals in Breast Milk

    Science.gov (United States)

    Most of the information available on environmental chemicals in breast milk is focused on persistent, lipophilic chemicals; the database on levels of these chemicals has expanded substantially since the 1950s. Currently, various types of chemicals are measured in breast milk and ...

  6. Chemical and Petrochemical Sector

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2009-07-01

    This publication is a background document on the global chemical and petrochemical sector for the IEA publication Energy Technology Transitions in Industry (IEA, 2009). It provides further, more detailed information on the methodology and data issues for energy efficiency indicators for the sector. The indicators discussed offer insight regarding the energy efficiency improvement potential in the short- to medium-term (by proven technologies).

  7. Pesticides: chemicals for survival

    International Nuclear Information System (INIS)

    Lindquist, D.A.

    1981-01-01

    Pesticides are chemicals used to control pests such as insects, weeds, plant diseases, nematodes, and rodents. The increased use of pesticides since 1945 has greatly aided the increase in crop production, protected livestock from diseases such as trypanosomiasis, protected man from diseases such as malaria and filarisis, decreased losses of stored grain, and has generally improved man's welfare. Despite the enormous benefits derived from pesticides these chemicals are not problem-free. Many pesticides are toxic to living organisms and interfere with specific biochemical systems. To measure the very small quantities of a pesticide radiolabelled chemicals are frequently essential, particularly to measure changes in the chemical structure of the pesticide, movement of the pesticide in soil, plants, or animals, amounts of pesticide going through various steps in food processing, etc. The use of radiolabelled pesticides is shortly shown for metabolism of the pesticide in crop species, metabolism in ruminant, in chickens and eggs, in soil, and possibly leaching and sorption in soil, hydrolysis, bio-concentration, microbial and photodegradation, and toxicity studies

  8. Dimensions of chemical science

    Indian Academy of Sciences (India)

    C N R RAO. Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India. e-mail: ... century with Lavoisier when he propounded ideas on chemical ... we come to recognize that new trends in chemistry started after the ...

  9. Nuclear and chemical data

    Energy Technology Data Exchange (ETDEWEB)

    De Regge, P.

    1978-12-15

    The neutron fission yield and other nuclear and chemical data of interest to the nuclear applications of mass spectrometry (mainly in the field of burnup determination) are examined. The performance of those determinations and the achievable accuracy should match the needs of the users of the data produced. 3 figures, 2 tables. (RWR)

  10. Chemical hygiene plan

    International Nuclear Information System (INIS)

    1994-09-01

    This plan was written to administer and monitor safety measures and chemical hygiene principles in the TAC Uranium Mill Tailing Remedial Action Project sample preparation facility in Albuquerque, New Mexico. It applies to toxic and/or hazardous materials to radioactive materials

  11. Chemical Aspects of Dentistry.

    Science.gov (United States)

    Helfman, Murry

    1982-01-01

    Dental caries (tooth decay) and periodontal (gum) disease are treated/prevented by procedures utilizing chemical expertise. Procedures and suggestions on how they might be incorporated into the high school chemistry curriculum are described. Specific topics discussed include dental caries, fluoride, diet, tooth decay prevention, silver amalgan,…

  12. Chemical forms of radioiodine

    International Nuclear Information System (INIS)

    Tachikawa, Enzo

    1979-01-01

    Release of radioiodine built-up during reactor operations presents a potential problem from the standpoint of environmental safety. Among the chemical forms of radioiodine, depending upon the circumstances, organic iodides cast a most serious problem because of its difficulties in the trapping and because of its stability compared to other chemical forms. Furthermore, pellet-cladding interaction (PCl) fuel failures in LWR fuel rods are believed to be stress corrosion cracks caused by embrittling fission product species, radioiodine. To deal with these problems, knowledge is required on the chemical behaviors of radioiodine in and out of fuels, as well as the release behaviors from fuels. Here a brief review is given of these respects, in aiming at clearing-up the questions still remaining unknown. The data seem to indicate that radioiodine exists as a combined form in fuels. upon heating slightly irradiated fuels, the iodine atoms are released in a chemical form associated with uranium atoms. Experiments, however, as needed with specimen of higher burnup, where the interactions of radioiodine with metallic fission products could be favored. The dominant release mechanism of radioiodine under normal operating temperatures will be diffusion to grain boundaries leading to open surfaces. Radiation-induced internal traps, however, after the rate of diffusion significantly. The carbon sources of organic iodides formed under various conditions and its formation mechanisms have also been considered. (author)

  13. Power plant chemical technology

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-01

    17 contributions covering topies of fossil fuel combustion, flue gas cleaning, power plant materials, corrosion, water/steam cycle chemistry, monitoring and control were presented at the annual meeting devoted to Power Plant Chemical Technology 1996 at Kolding (Denmark) 4-6 September 1996. (EG)

  14. Tourniquet associated chemical burn

    Directory of Open Access Journals (Sweden)

    Jae-Hyuk Yang

    2012-01-01

    Full Text Available Chemical burn under pneumatic tourniquet is an iatrogenic preventable injury and is rarely reported in the literature. The two important mechanisms are maceration (friction and wetness underneath the tourniquent. In this report, our experience with two illustrative patients who presented with iatrogenic tourniquet associated burn is described.

  15. Chemical analysis report 2014

    International Nuclear Information System (INIS)

    Elbouzidi, Saliha; Elyahyaoui, Adil; Ghassan, Acil; Marah, Hamid

    2014-01-01

    This report highlights the results of chemical analyzes related to Major elements, traces and heavy metals carried out at the CNESTEN DASTE in Rabat (Morocco), on behalf of Senegal. These analyzes cover 120 samples. The report presents the analytical techniques used (parameters and methods), a legend and the results tables.

  16. Chemical analysis report 2015

    International Nuclear Information System (INIS)

    2015-01-01

    This report highlights the results of chemical analyzes of fluorides, bromides, lithium and boron carried out at the CNESTEN DASTE in Rabat (Morocco), on behalf of Senegal. These analyzes cover 120 samples. The report presents the analytical techniques used (parameters and methods), a legend and the results tables.

  17. Microfluidics for chemical processing

    NARCIS (Netherlands)

    Gardeniers, Johannes G.E.

    2006-01-01

    Microfluidic systems, and more specifically, microfluidic chips, have a number of features that make them particularly useful for the study of chemical reactions on-line. The present paper will discuss two examples, the study of fluidic behaviour at high pressures and the excitation and detection of

  18. Modeling chemical kinetics graphically

    NARCIS (Netherlands)

    Heck, A.

    2012-01-01

    In literature on chemistry education it has often been suggested that students, at high school level and beyond, can benefit in their studies of chemical kinetics from computer supported activities. Use of system dynamics modeling software is one of the suggested quantitative approaches that could

  19. Electro-chemical grinding

    Science.gov (United States)

    Feagans, P. L.

    1972-01-01

    Electro-chemical grinding technique has rotation speed control, constant feed rates, and contour control. Hypersonic engine parts of nickel alloys can be almost 100% machined, keeping tool pressure at virtual zero. Technique eliminates galling and permits constant surface finish and burr-free interrupted cutting.

  20. Chemicals in material cycles

    DEFF Research Database (Denmark)

    Pivnenko, Kostyantyn; Eriksson, Eva; Astrup, Thomas Fruergaard

    2015-01-01

    Material recycling has been found beneficial in terms of resource and energy performance and is greatly promoted throughout the world. A variety of chemicals is used in materials as additives and data on their presence is sparse. The present work dealt with paper as recyclable material and diisob...

  1. Chemical relationship between Pinaceae

    NARCIS (Netherlands)

    Niemann, G.J.; Genderen, H.H. van

    1980-01-01

    Fingerprints of phenolic compounds of leaf extracts of eleven pine species have been made by paper chromatography and HPLC. The results suggest a chemical relationship which agrees fairly well with those based on immunological and morphological characters but not always with the classification

  2. Chemical Utilisation of CO

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 20; Issue 2. Chemical Utilisation of CO2: A Challenge for the Sustainable World. Dinesh Jagadeesan Bhaskar Joshi Prashant Parameswaran. General Article Volume 20 Issue 2 February 2015 pp 165-176 ...

  3. Chemical warfare in termites

    Czech Academy of Sciences Publication Activity Database

    Šobotník, Jan; Jirošová, Anna; Hanus, Robert

    2010-01-01

    Roč. 56, č. 9 (2010), s. 1012-1021 ISSN 0022-1910 R&D Projects: GA AV ČR IAA600550614 Institutional research plan: CEZ:AV0Z40550506 Keywords : Isoptera * chemical defense * exocrine gland * frontal gland Subject RIV: CC - Organic Chemistry Impact factor: 2.310, year: 2010

  4. Chemical Absorption Materials

    DEFF Research Database (Denmark)

    Thomsen, Kaj

    2011-01-01

    Chemical absorption materials that potentially can be used for post combustion carbon dioxide capture are discussed. They fall into five groups, alkanolamines, alkali carbonates, ammonia, amino acid salts, and ionic liquids. The chemistry of the materials is discussed and advantages and drawbacks...

  5. Chemical Safety – Introduction

    CERN Multimedia

    DG Unit

    2009-01-01

    A course of "Chemical Safety – Introduction" will be held in English on 29 May 2009, 9:30-12:00. There are some places left. If you are interested in participating, please register on the Training Catalogue. You will then receive an invitation by email.

  6. Multiple Chemical Sensitivity

    DEFF Research Database (Denmark)

    Junge, Anne Gram

    Et voksende antal mennesker i Danmark oplever at være overfølsomme over for dufte og kemikalier. Imidlertid er den tilskrevne diagnose Multiple Chemical Sensitivity (MCS) ikke medicinsk anerkendt i Danmark pga. mangel på organiske og patofysiologisk basis for symptomerne. Dette speciale bygger på...

  7. Plants' essential chemical elements

    Science.gov (United States)

    Kevin T. Smith

    2007-01-01

    Every garden center and hardware store sells fertilizer guaranteed to "feed" plants. In a strict sense, we can't feed plants. Food contains an energy source. Green plants capture solar energy and make their own food through photosynthesis! Photosynthesis and other metabolic processes require chemical elements in appropriate doses for plants to survive...

  8. Chemical modification of wood

    Science.gov (United States)

    Roger M. Rowell

    2007-01-01

    After millions of years of evolution, wood was designed to perform in a wet environment, and nature is programmed to recycle it, in a timely way, back to the basic building blocks of carbon dioxide and water through biological, thermal, aqueous, photochemical, chemical, and mechanical degradation. The properties of wood are, for the most part, a result of the chemistry...

  9. Metrology for Chemical Engineers

    DEFF Research Database (Denmark)

    Heydorn, Kaj; Hansen, Elo Harald

    2001-01-01

    The first full-semester course on Quality Assurance in Chemical Measurement was held at the Technical University of Denmark from September to December 1999. The course required sufficient knowledge of basic statistics to understand and apply the methods recommended in ISO 5725-1/6 Accuracy of Mea...

  10. Common Sense and Chemicals

    Science.gov (United States)

    Roy, Ken

    2010-01-01

    This month's column features two true stories about the use of chemicals in the middle school science classroom. The lesson of these stories is simple. Certainly, it is prudent to have age-appropriate experiences in science, given the developmental constraints of students in middle school. On the other hand, when the curriculum necessitates…

  11. Global chemical pollution

    International Nuclear Information System (INIS)

    Travis, C.C.; Hester, S.T.

    1991-01-01

    Over the past decade, public and governmental awareness of environmental problems has grown steadily, with an accompanying increase in the regulation of point sources of pollution. As a result, great strides have been made in cleaning polluted rivers and decreasing air pollution near factories. However, traditional regulatory approaches to environmental pollution have focused primarily on protecting the maximally exposed individual located in the immediate vicinity of the pollution source. Little attention has been given to the global implications of human production and use of synthetic chemicals. A consensus is emerging that even trace levels of environmental contamination can have potentially devastating environmental consequences. The authors maintain that ambient levels of pollution have risen to the point where human health is being affected on a global scale. Atmospheric transport is recognized as the primary mode of global distribution and entry into the food chain for organic chemicals. The following are examples of global chemical pollutants that result in human exposure of significant proportions: PCBs, dioxins, benzene, mercury and lead. Current regulatory approaches for environmental pollution do not incorporate ways of dealing with global pollution. Instead the major focus has been on protecting the maximally exposed individual. If we do not want to change our standard of living, the only way to reduce global chemical pollution is to make production and consumption processes more efficient and to lower the levels of production of these toxic chemicals. Thus the only reasonable solution to global pollution is not increased regulation of isolated point sources, but rather an increased emphasis on waste reduction and materials recycling. Until we focus on these issues, we will continue to experience background cancer risk in the 10 -3 range

  12. Biomass pyrolysis for chemicals

    Energy Technology Data Exchange (ETDEWEB)

    De Wild, P.

    2011-07-15

    The problems associated with the use of fossil fuels demand a transition to renewable sources (sun, wind, water, geothermal, biomass) for materials and energy where biomass provides the only renewable source for chemicals. In a biorefinery, biomass is converted via different technologies into heat, power and various products. Here, pyrolysis (thermal degradation without added oxygen) of lignocellulosic biomass can play an important role, because it leads to an array of useful chemicals. Examples are furfural and acetic acid from hemicellulose, levoglucosan from cellulose and phenols and biochar from lignin. Since the three major biomass polymers hemicellulose, cellulose and lignin possess dissimilar thermal stabilities and reactivities, type and amount of degradation products are tunable by proper selection of the pyrolysis conditions. To determine if step-wise pyrolysis would be suitable for the production of chemicals, staged degasification of lignocellulosic biomass was studied. Due to limited yields, a hot pressurized water pre-treatment (aquathermolysis) followed by pyrolysis was subsequently developed as an improved version of a staged approach to produce furfural and levoglucosan from the carbohydrate fraction of the biomass. Lignin is the only renewable source for aromatic chemicals. Lignocellulosic biorefineries for bio-ethanol produce lignin as major by-product. The pyrolysis of side-streams into valuable chemicals is of prime importance for a profitable biorefinery. To determine the added-value of lignin side-streams other than their use as fuel for power, application research including techno-economic analysis is required. In this thesis, the pyrolytic valorisation of lignin into phenols and biochar was investigated and proven possible.

  13. Accurate quantum chemical calculations

    Science.gov (United States)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Taylor, Peter R.

    1989-01-01

    An important goal of quantum chemical calculations is to provide an understanding of chemical bonding and molecular electronic structure. A second goal, the prediction of energy differences to chemical accuracy, has been much harder to attain. First, the computational resources required to achieve such accuracy are very large, and second, it is not straightforward to demonstrate that an apparently accurate result, in terms of agreement with experiment, does not result from a cancellation of errors. Recent advances in electronic structure methodology, coupled with the power of vector supercomputers, have made it possible to solve a number of electronic structure problems exactly using the full configuration interaction (FCI) method within a subspace of the complete Hilbert space. These exact results can be used to benchmark approximate techniques that are applicable to a wider range of chemical and physical problems. The methodology of many-electron quantum chemistry is reviewed. Methods are considered in detail for performing FCI calculations. The application of FCI methods to several three-electron problems in molecular physics are discussed. A number of benchmark applications of FCI wave functions are described. Atomic basis sets and the development of improved methods for handling very large basis sets are discussed: these are then applied to a number of chemical and spectroscopic problems; to transition metals; and to problems involving potential energy surfaces. Although the experiences described give considerable grounds for optimism about the general ability to perform accurate calculations, there are several problems that have proved less tractable, at least with current computer resources, and these and possible solutions are discussed.

  14. Global Controllability of Chemical Reactions

    OpenAIRE

    Drexler, Dániel András; Tóth, János

    2015-01-01

    Controllability of chemical reactions is an important problem in chemical engineering science. In control theory, analysis of the controllability of linear systems is well-founded, however the dynamics of chemical reactions is usually nonlinear. Global controllability properties of chemical reactions are analyzed here based on the Lie-algebra of the vector fields associated to elementary reactions. A chemical reaction is controllable almost everywhere if all the reaction rate coefficients can...

  15. Surfactant loss control in chemical flooding: Spectroscopic and calorimetric study of adsorption and precipitation on reservoir minerals. Annual report, September 30, 1992--September 30, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Somasundaran, P.

    1994-07-01

    The aim of this research project is to investigate mechanisms underlying adsorption and surface precipitation of flooding surfactants on reservoir minerals. Effects of surfactant structure, surfactant combinations, various inorganic and polymeric species, and solids mineralogy will be determined. A multi-pronged approach consisting of micro & nano spectroscopy, microcalorimetry, electrokinetics, surface tension and wettability; is used in this study. The results obtained should help in controlling surfactant loss in chemical flooding and in developing optimum structures and conditions for efficient chemical flooding processes. During the first year of this three year contract, adsorption of single surfactants and select surfactant mixtures was studied at the solid-liquid and gas-liquid interfaces. Surfactants studied include alkyl xylene sulfonates, polyethoxylated alkyl phenols, octaethylene glycol mono n-decyl ether, and tetradecyl trimethyl ammonium chloride. Adsorption of surfactant mixtures of varying composition was also investigated. The microstructure of the adsorbed layer was characterized using fluorescence spectroscopy. Changes interfacial properties such as wettability, electrokinetics and stability of reservoir minerals were correlated with the amount of reagent adsorbed. Strong effects of the structure of the surfactant and position of functional groups were revealed.

  16. Surfactant loss control in chemical flooding spectroscopic and calorimetric study of adsorption and precipitation on reservoir minerals. Annual report, September 30, 1992--September 30 1995

    Energy Technology Data Exchange (ETDEWEB)

    Casteel, J. [Bartlesville Project Office, OK (United States)

    1996-07-01

    The aim of this research project was to investigate mechanisms governing adsorption and surface precipitation of flooding surfactants on reservoir minerals. Effects of surfactant structure, surfactant combinations, various inorganic and polymeric species, and solids mineralogy have been determined. A multi-pronged approach consisting of micro & nano spectroscopy, electrokinetics, surface tension and wettability is used in this study. The results obtained should help in controlling surfactant loss in chemical flooding and in developing optimum structures and conditions for efficient chemical flooding processes. During the three years contract period, adsorption of single surfactants and select surfactant mixtures was studied at the solid-liquid and gas-liquid interfaces. Alkyl xylene sulfonates, polyethoxylated alkyl phenols, octaethylene glycol mono n-decyl ether, and tetradecyl trimethyl ammonium chloride were the surfactants studied. Adsorption of surfactant mixtures of varying composition was also investigated. The microstructure of the adsorbed layer was characterized using fluorescence spectroscopy. Changes in interfacial properties such as wettability, electrokinetics and stability of reservoir minerals were correlated with the amounts of reagent adsorbed. Strong effects of the structure of the surfactant and position of functional groups were revealed. Changes of microstructure upon dilution (desorption) were also studied. Presence of the nonionic surfactants in mixed aggregate leads to shielding of the charge of ionic surfactants which in turn promotes aggregation but reduced electrostatic attraction between the charged surfactant and the mineral surface. Strong consequences of surfactant interactions in solution on adsorption as well as correlations between monomer concentration in mixtures and adsorption were revealed.

  17. Combining in situ chemical oxidation, stabilization, and anaerobic bioremediation in a single application to reduce contaminant mass and leachability in soil.

    Science.gov (United States)

    Cassidy, Daniel P; Srivastava, Vipul J; Dombrowski, Frank J; Lingle, James W

    2015-10-30

    Laboratory batch reactors were maintained for 32 weeks to test the potential for an in situ remedy that combines chemical oxidation, stabilization, and anaerobic bioremediation in a single application to treat soil from a manufactured gas plant, contaminated with polycyclic aromatic hydrocarbons (PAH) and benzene, toluene, ethylbenzene, and xylenes (BTEX). Portland cement and slaked lime were used to activate the persulfate and to stabilize/encapsulate the contaminants that were not chemically oxidized. Native sulfate-reducing bacteria degraded residual contaminants using the sulfate left after persulfate activation. The ability of the combined remedy to reduce contaminant mass and leachability was compared with NaOH-activated persulfate, stabilization, and sulfate-reducing bioremediation as stand-alone technologies. The stabilization amendments increased pH and temperature sufficiently to activate the persulfate within 1 week. Activation with both stabilization amendments and NaOH removed between 55% and 70% of PAH and BTEX. However, combined persulfate and stabilization significantly reduced the leachability of residual BTEX and PAH compared with NaOH activation. Sulfide, 2-naphthoic acid, and the abundance of subunit A of the dissimilatory sulfite reductase gene (dsrA) were used to monitor native sulfate-reducing bacteria, which were negatively impacted by activated persulfate, but recovered completely within weeks. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. [Chemical risk in farming].

    Science.gov (United States)

    Moretto, Angelo

    2013-01-01

    The most important chemical risks in agriculture are plant protection products. Exposure evaluation in agriculture is not an easy task and cannot be carried out with the tools and methodologies of industrial exposures. However, toxicological studies on plant protection products, that are compulsory, provide a lot of useful information for actual risk assessment. Exposure evaluation can be carried out on the basis of exposure models and on semiquantitative measures based on the observation of the activity as it is carried our by the farmer. It is therefore possible to develop risk profiles that can guide exposure evaluation and health surveillance. Concentrated animal feeding operations are associated with several chemical risks including disinfectants, antibiotics, and gases such as ammonia and hydrogen sulfide, in addition to organic dusts and endotoxins.

  19. Chemical Engineering in Space

    Science.gov (United States)

    Lobmeyer, Dennis A.; Meneghelli, Barry; Steinrock, Todd (Technical Monitor)

    2001-01-01

    The aerospace industry has long been perceived as the domain of both physicists and mechanical engineers. This perception has endured even though the primary method of providing the thrust necessary to launch a rocket into space is chemical in nature. The chemical engineering and chemistry personnel behind the systems that provide access to space have labored in the shadows of the physicists and mechanical engineers. As exploration into the cosmos moves farther away from Earth, there is a very distinct need for new chemical processes to help provide the means for advanced space exploration. The state of the art in launch systems uses chemical propulsion systems, primarily liquid hydrogen and liquid oxygen, to provide the energy necessary to achieve orbit. As we move away from Earth, there are additional options for propulsion. Unfortunately, few of these options can compare to the speed or ease of use provided by the chemical propulsion agents. It is with great care and significant cost that gaseous compounds such as hydrogen and oxygen are liquefied and become dense enough to use for rocket fuel. These low-temperature liquids fall within a specialty area known as cryogenics. Cryogenics, the science and art of producing cold operating conditions for use on Earth, in orbit, or on some other nonterrestrial body, has become increasingly important to our ability to travel within our solar system. The production of cryogenic fuels and the long-term storage of these fluids are necessary for travel. As our explorations move farther away from Earth, we need to address how to produce the necessary fuels to make a round-trip. The cost and the size of these expeditions are extreme at best. If we take everything necessary for our survival for the round-trip, we invalidate any chance of travel in the near future. As with the early explorers on Earth, we need to harvest much of our energy and our life support from the celestial bodies. The in situ production of these energy

  20. Biocatalysis for Biobased Chemicals

    Science.gov (United States)

    de Regil, Rubén; Sandoval, Georgina

    2013-01-01

    The design and development of greener processes that are safe and friendly is an irreversible trend that is driven by sustainable and economic issues. The use of Biocatalysis as part of a manufacturing process fits well in this trend as enzymes are themselves biodegradable, require mild conditions to work and are highly specific and well suited to carry out complex reactions in a simple way. The growth of computational capabilities in the last decades has allowed Biocatalysis to develop sophisticated tools to understand better enzymatic phenomena and to have the power to control not only process conditions but also the enzyme’s own nature. Nowadays, Biocatalysis is behind some important products in the pharmaceutical, cosmetic, food and bulk chemicals industry. In this review we want to present some of the most representative examples of industrial chemicals produced in vitro through enzymatic catalysis. PMID:24970192

  1. Chemical and UV Mutagenesis.

    Science.gov (United States)

    Bose, Jeffrey L

    2016-01-01

    The ability to create mutations is an important step towards understanding bacterial physiology and virulence. While targeted approaches are invaluable, the ability to produce genome-wide random mutations can lead to crucial discoveries. Transposon mutagenesis is a useful approach, but many interesting mutations can be missed by these insertions that interrupt coding and noncoding sequences due to the integration of an entire transposon. Chemical mutagenesis and UV-based random mutagenesis are alternate approaches to isolate mutations of interest with the potential of only single nucleotide changes. Once a standard method, difficulty in identifying mutation sites had decreased the popularity of this technique. However, thanks to the recent emergence of economical whole-genome sequencing, this approach to making mutations can once again become a viable option. Therefore, this chapter provides an overview protocol for random mutagenesis using UV light or DNA-damaging chemicals.

  2. Cyanobacterial chemical production.

    Science.gov (United States)

    Case, Anna E; Atsumi, Shota

    2016-08-10

    The increase in global temperatures caused by rising CO2 levels necessitates the development of alternative sources of fuel and chemicals. One appealing alternative that has been receiving increased attention in recent years is the photosynthetic conversion of atmospheric CO2 to biofuels and chemical products using genetically engineered cyanobacteria. This can help to not only provide an alternate "greener" source for some of the most popular petroleum based products but it can also help to reduce atmospheric CO2. Utilizing cyanobacteria rather than plants allows for reduced land requirements and reduces competition with food crops. This review discusses advancements in the field since 2012 with a particular emphasis on production of hydrocarbons. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Chemical and petrochemical industry

    Science.gov (United States)

    Staszak, Katarzyna

    2018-03-01

    The potential sources of various metals in chemical and petrochemical processes are discussed. Special emphasis is put on the catalysts used in the industry. Their main applications, compositions, especially metal contents are presented both for fresh and spent ones. The focus is on the main types of metals used in catalysts: the platinum-group metals, the rare-earth elements, and the variety of transition metals. The analysis suggested that chemical and petrochemical sectors can be considered as the secondary source of metals. Because the utilization of spent refinery catalysts for metal recovery is potentially viable, different methods were applied. The conventional approaches used in metal reclamation as hydrometallurgy and pyrometallurgy, as well as new methods include bioleaching, were described. Some industrial solutions for metal recovery from spent solution were also presented.

  4. The Use of Chemical-Chemical Interaction and Chemical Structure to Identify New Candidate Chemicals Related to Lung Cancer.

    Directory of Open Access Journals (Sweden)

    Lei Chen

    Full Text Available Lung cancer causes over one million deaths every year worldwide. However, prevention and treatment methods for this serious disease are limited. The identification of new chemicals related to lung cancer may aid in disease prevention and the design of more effective treatments. This study employed a weighted network, constructed using chemical-chemical interaction information, to identify new chemicals related to two types of lung cancer: non-small lung cancer and small-cell lung cancer. Then, a randomization test as well as chemical-chemical interaction and chemical structure information were utilized to make further selections. A final analysis of these new chemicals in the context of the current literature indicates that several chemicals are strongly linked to lung cancer.

  5. Chemical environment in cements

    International Nuclear Information System (INIS)

    Glasser, F.B.; Angus, M.J.; McCulloch, C.E.; Macphee, D.; Rahman, A.A.

    1984-01-01

    The alkalinity of Portland cements is responsible for precipitation and low solubility of many radwastes species. The sources of alkalinity are evaluated and two chemical models, based on experimental and theoretical data presented enabling the effect of blending agents (PFA, silica fume, etc.) to be evaluated and the alkalinity of the system at longer ages predicted. The data take the form of a solubility model which is applicable to non-heat generating wastes. 7 refs., 10 figs

  6. Chemical sensor system

    Science.gov (United States)

    Darrach, Murray R. (Inventor); Chutjian, Ara (Inventor)

    2008-01-01

    A chemical sensing apparatus and method for the detection of sub parts-per-trillion concentrations of molecules in a sample by optimizing electron utilization in the formation of negative ions is provided. A variety of media may be sampled including air, seawater, dry sediment, or undersea sediment. An electrostatic mirror is used to reduce the kinetic energy of an electron beam to zero or near-zero kinetic energy.

  7. Chemical product dictionary

    International Nuclear Information System (INIS)

    Mun, Seong Myeong

    1989-10-01

    This book deals with synthetic rubber in the first part: Poly norbornene rubber, Polysulfide rubber, FKM, Fluoridated rubber, BR, CR, Syndiotactic 1,2 - Polybutadiene, Silicone rubber, IR, IIR, ACM, Liquid rubber, SBR, EVA, Co, NBR, TPE, SBC, TPVC, TPO, TPU, TPAE, TPEE, Urethane rubber, CSM, and propylene oxide rubber. The second part describes organic rubber chemical carbon black, processing aid, zinc salts of fatty acids, Exton L-2, Exton k-1, and vulcanizing agent.

  8. Chemical constituents of Asparagus

    Science.gov (United States)

    Negi, J. S.; Singh, P.; Joshi, G. P.; Rawat, M. S.; Bisht, V. K.

    2010-01-01

    Asparagus species (family Liliaceae) are medicinal plants of temperate Himalayas. They possess a variety of biological properties, such as being antioxidants, immunostimulants, anti-inflammatory, antihepatotoxic, antibacterial, antioxytocic, and reproductive agents. The article briefly reviews the isolated chemical constituents and the biological activities of the plant species. The structural formula of isolated compounds and their distribution in the species studied are also given. PMID:22228964

  9. Chemical transport reactions

    CERN Document Server

    Schäfer, Harald

    2013-01-01

    Chemical Transport Reactions focuses on the processes and reactions involved in the transport of solid or liquid substances to form vapor phase reaction products. The publication first offers information on experimental and theoretical principles and the transport of solid substances and its special applications. Discussions focus on calculation of the transport effect of heterogeneous equilibria for a gas motion between equilibrium spaces; transport effect and the thermodynamic quantities of the transport reaction; separation and purification of substances by means of material transport; and

  10. Chemical thermodynamics. An introduction

    Energy Technology Data Exchange (ETDEWEB)

    Keszei, Ernoe [Budapest Univ. (Hungary). Dept. of Physical Chemistry

    2012-07-01

    Eminently suitable as a required textbook comprising complete material for or an undergraduate chemistry major course in chemical thermodynamics. Clearly explains details of formal derivations that students can easily follow and so master applied mathematical operations. Offers problems and solutions at the end of each chapter for self-test and self- or group study. This course-derived undergraduate textbook provides a concise explanation of the key concepts and calculations of chemical thermodynamics. Instead of the usual 'classical' introduction, this text adopts a straightforward postulatory approach that introduces thermodynamic potentials such as entropy and energy more directly and transparently. Structured around several features to assist students' understanding, Chemical Thermodynamics: - Develops applications and methods for the ready treatment of equilibria on a sound quantitative basis. - Requires minimal background in calculus to understand the text and presents formal derivations to the student in a detailed but understandable way. - Offers end-of-chapter problems (and answers) for self-testing and review and reinforcement, of use for self- or group study. This book is suitable as essential reading for courses in a bachelor and master chemistry program and is also valuable as a reference or textbook for students of physics, biochemistry and materials science.

  11. Metabolomics in chemical ecology.

    Science.gov (United States)

    Kuhlisch, Constanze; Pohnert, Georg

    2015-07-01

    Chemical ecology elucidates the nature and role of natural products as mediators of organismal interactions. The emerging techniques that can be summarized under the concept of metabolomics provide new opportunities to study such environmentally relevant signaling molecules. Especially comparative tools in metabolomics enable the identification of compounds that are regulated during interaction situations and that might play a role as e.g. pheromones, allelochemicals or in induced and activated defenses. This approach helps overcoming limitations of traditional bioassay-guided structure elucidation approaches. But the power of metabolomics is not limited to the comparison of metabolic profiles of interacting partners. Especially the link to other -omics techniques helps to unravel not only the compounds in question but the entire biosynthetic and genetic re-wiring, required for an ecological response. This review comprehensively highlights successful applications of metabolomics in chemical ecology and discusses existing limitations of these novel techniques. It focuses on recent developments in comparative metabolomics and discusses the use of metabolomics in the systems biology of organismal interactions. It also outlines the potential of large metabolomics initiatives for model organisms in the field of chemical ecology.

  12. Evaporation of multicomponent chemical spills: When is liquid phase resistance significant?

    International Nuclear Information System (INIS)

    Berger, D.; Mackay, D.

    1993-01-01

    When chemicals are spilled on land or water, it is important to be able to estimate evaporation rates accurately. Conventional models used to predict evaporation rates of multicomponent spills assume that the entire resistance to evaporation lies in the vapor phase. Under certain conditions, an additional liquid phase resistance may be introduced, resulting in retarded evaporation rates. Existing models may thus fail to predict spill behavior accurately. A study is described whose objective is to elucidate the significance of the liquid phase resistance. Evaporation experiments were conducted in which a thin layer of synthetic oil (mineral oil enriched with compounds such as pentane, hexane, toluene, octane, and p-xylene) was exposed to prolonged evaporation in a metal tray at controlled wind speeds. Bulk samples of the spill layer were taken at specific time intervals and their composition was determined by gas chromatographic analysis. The results are compared to those from a theoretical model and to gas stripping experiments. The model is based on the evaporative flux equation incorporating Raoult's law; inputs are the air-oil partition coefficient for each component and the composition of the synthetic oil on a volume and mole fraction basis. The study has enabled the formation of vertical concentration profiles to be examined and liquid phase mass transfer coefficients to be estimated. The results imply that liquid-phase resistance effects are likely to be important for the most volatile components. Contaminated areas may thus continue to be hazardous, even though model predictions indicate otherwise. 7 refs., 3 figs., 2 tabs

  13. chemical studies on the extraction of certain metal ions from aqueous solution by liquid emulsion membrane

    International Nuclear Information System (INIS)

    Kassem, A.T.

    2011-01-01

    In this thesis four systems are addressed related to the use of liquid emulsion membranes (ELM) based on Co(III)dicarbiolide and. The system was dedicated for permeation of cadmium , cobalt Nickel and lead for use of this system for preconcentration and separation of cadmium, cobalt, nickel and lead. The work carried out in this thesis is presented in three parts, namely; introduction, experimental and results and discussion.The first chapter is the introduction which includes aim of work, basic concepts of liquid membranes; liquid emulsion membranes; different models of emulsion permeation, literature survey of extraction chemistry of cadmium, cobalt, nickel and lead. Chapter two includes the experimental part. In this part detailed outlines on the chemicals and different elements used were given. Different instruments as well as analytical techniques were outlines. The preparation of liquid emulsion membrane and the permeation techniques were presented in details. The third chapter deals with the results and discussion. This chapter is divided into four main parts, the four parts is concerned with cadmium/Co(III) dicarbolide/NTA, EDTA, DPTA and DCTA systems. In this part the permeation of Cd(II) aqueous solution by the membrane used was experimented based on liquid-liquid extraction studies of cadmium from different sodium chloride molarities (from 0.01 to 0.1 M) by 0.01 M Cobalt(III) dicarbolides. It was found that the extraction of with cadmium is higher following in the first system, the permeation of the toxic elements, Cd(II) from HCl/sodium chloride medium was carried out using liquid emulsion membrane containing Co(III)dicarbiolide in xylene as carrier, Spain 80/ Spain 85(1:3) as surfactant and NTA, EDTA, DPTA and DCTA as a stripping solutions.

  14. Achieving synergy between chemical oxidation and stabilization in a contaminated soil.

    Science.gov (United States)

    Srivastava, Vipul J; Hudson, Jeffrey Michael; Cassidy, Daniel P

    2016-07-01

    Eight in situ solidification/stabilization (ISS) amendments were tested to promote in situ chemical oxidation (ISCO) with activated persulfate (PS) in a contaminated soil. A 3% (by weight) dose of all ISS amendments selected for this study completely activated a 1.5% dose of PS within 3 h by raising temperatures above 30 °C (heat activation) and/or increasing pH above 10.5 (alkaline activation). Heat is released by the reaction of CaO with water, and pH increases because this reaction produces Ca(OH)2. Heat activation is preferred because it generates 2 mol of oxidizing radicals per mole of PS, whereas alkaline activation releases only 1. The relative contribution of heat vs. alkaline activation increased with CaO content of the ISS amendment, which was reflected by enhanced contaminant oxidation with increasing CaO content, and was confirmed by comparing to controls promoting purely heat or alkaline (NaOH) activation. The test soil was contaminated with benzene, toluene, ethylbenzene, and xylenes (BTEX) and polycyclic aromatic hydrocarbons (PAH), particularly naphthalene (NAP). ISS-activated PS oxidized between 47% and 84% of the BTEX & NAP, and between 13% and 33% of the higher molecular weight PAH. ISS-activated PS reduced the leachability of BTEX & NAP by 76%-91% and of the 17 PAH by 83%-96%. Combined ISCO/ISS reduced contaminant leachability far than ISCO or ISS treatments alone, demonstrating the synergy that is possible with combined remedies. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Adsorption properties of the SAPO-5 molecular sieve

    KAUST Repository

    Hu, Enping; Lai, Zhiping; Wang, Kean

    2010-01-01

    The adsorption properties of an aluminophosphate molecular sieve, SAPO-5, were measured for a number of gases and vapors, including N2, water, isopropanol, and xylenes. The data showed that SAPO-5 is quite hydrophobic and has a strong selectivity of o-xylene over its isomers m- and p-xylene. © 2010 American Chemical Society.

  16. Adsorption properties of the SAPO-5 molecular sieve

    KAUST Repository

    Hu, Enping

    2010-09-09

    The adsorption properties of an aluminophosphate molecular sieve, SAPO-5, were measured for a number of gases and vapors, including N2, water, isopropanol, and xylenes. The data showed that SAPO-5 is quite hydrophobic and has a strong selectivity of o-xylene over its isomers m- and p-xylene. © 2010 American Chemical Society.

  17. [Chemical hazards when working with solvent glues].

    Science.gov (United States)

    Domański, Wojciech; Makles, Zbigniew

    2012-01-01

    Solvent glues are used in a wide variety of industries, e.g., textile, footwear and rubber. The problem of workers' exposure to solvent vapors is rarely tackled within the area of occupational safety and health in small and medium-sized enterprises. In order to assess exposure to solvents, organic solvents emitted by glues were identified in the samples of workplace air. The concentration of acetone, benzene, cyclohexane, ethylbenzene, n-hexane, methylcyclohexane, butyl acetate and toluene were determined. The obtained results evidenced the presence of cyclohexane, ethylbenzene, ethylcyclohexane, heptane, n-hexane, o-xylene, methylcyclohexane, methylcyclopentane, butyl acetate and toluene in workplace air. The concentration of those compounds in workplace air was low, usually below 0.15 of MAC. At some workstations the presence of benzene was also observed. Occupational risk was assessed at workstations where gluing took place. It showed that the risk at those workstations was medium or low.

  18. Chemical systems, chemical contiguity and the emergence of life

    DEFF Research Database (Denmark)

    Kee, Terrence P.; Monnard, Pierre Alain

    2017-01-01

    to complex chemical systems over specific isolated functional apparatuses. We will summarize the recent advances in system chemistry and show that chemical systems in the geochemical context imply a form of chemical contiguity in the syntheses of the various molecules that precede modern biomolecules....

  19. Determinants of Exposure to Fragranced Product Chemical Mixtures in a Sample of Twins

    Directory of Open Access Journals (Sweden)

    Matthew O. Gribble

    2015-01-01

    Full Text Available Fragranced product chemical mixtures may be relevant for environmental health, but little is known about exposure. We analyzed results from an olfactory challenge with the synthetic musk fragrance 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethyl-cyclopento-γ-2-benzopyran (HHCB, and a questionnaire about attitudes toward chemical safety and use of fragranced products, in a sample of 140 white and 17 black twin pairs attending a festival in Ohio. Data for each product were analyzed using robust ordered logistic regressions with random intercepts for “twin pair” and “sharing address with twin”, and fixed effects for sex, age, education, and “ever being bothered by fragrances”. Due to the small number of black participants, models were restricted to white participants except when examining racial differences. Overall patterns of association were summarized across product-types through random-effects meta-analysis. Principal components analysis was used to summarize clustering of product use. The dominant axis of variability in fragranced product use was “more vs. less”, followed by a distinction between household cleaning products and personal care products. Overall, males used fragranced products less frequently than females (adjusted proportionate odds ratio 0.55, 95% confidence interval 0.33, 0.93. This disparity was driven by personal care products (0.42, 95% CI: 0.19, 0.96, rather than household cleaning products (0.79, 95% CI: 0.49, 1.25 and was particularly evident for body lotion (0.12, 95% CI: 0.05, 0.27. Overall usage differed by age (0.64, 95% CI: 0.43, 0.95 but only hand soap and shampoo products differed significantly. “Ever being bothered by fragrance” had no overall association (0.92, 95% CI: 0.65, 1.30 but was associated with laundry detergent use (0.46, 95% CI: 0.23, 0.93. Similarly, black vs. white differences on average were not significant (1.34, 95% CI: 0.55, 3.28 but there were apparent differences in use of

  20. Determinants of Exposure to Fragranced Product Chemical Mixtures in a Sample of Twins

    Science.gov (United States)

    Gribble, Matthew O.; Bandeen-Roche, Karen; Fox, Mary A.

    2015-01-01

    Fragranced product chemical mixtures may be relevant for environmental health, but little is known about exposure. We analyzed results from an olfactory challenge with the synthetic musk fragrance 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethyl-cyclopento-γ-2-benzopyran (HHCB), and a questionnaire about attitudes toward chemical safety and use of fragranced products, in a sample of 140 white and 17 black twin pairs attending a festival in Ohio. Data for each product were analyzed using robust ordered logistic regressions with random intercepts for “twin pair” and “sharing address with twin”, and fixed effects for sex, age, education, and “ever being bothered by fragrances”. Due to the small number of black participants, models were restricted to white participants except when examining racial differences. Overall patterns of association were summarized across product-types through random-effects meta-analysis. Principal components analysis was used to summarize clustering of product use. The dominant axis of variability in fragranced product use was “more vs. less”, followed by a distinction between household cleaning products and personal care products. Overall, males used fragranced products less frequently than females (adjusted proportionate odds ratio 0.55, 95% confidence interval 0.33, 0.93). This disparity was driven by personal care products (0.42, 95% CI: 0.19, 0.96), rather than household cleaning products (0.79, 95% CI: 0.49, 1.25) and was particularly evident for body lotion (0.12, 95% CI: 0.05, 0.27). Overall usage differed by age (0.64, 95% CI: 0.43, 0.95) but only hand soap and shampoo products differed significantly. “Ever being bothered by fragrance” had no overall association (0.92, 95% CI: 0.65, 1.30) but was associated with laundry detergent use (0.46, 95% CI: 0.23, 0.93). Similarly, black vs. white differences on average were not significant (1.34, 95% CI: 0.55, 3.28) but there were apparent differences in use of shampoo (0

  1. CHEMICAL STORAGE: MYTHS VERSUS REALITY

    International Nuclear Information System (INIS)

    Simmons, F.

    2007-01-01

    A large number of resources explaining proper chemical storage are available. These resources include books, databases/tables, and articles that explain various aspects of chemical storage including compatible chemical storage, signage, and regulatory requirements. Another source is the chemical manufacturer or distributor who provides storage information in the form of icons or color coding schemes on container labels. Despite the availability of these resources, chemical accidents stemming from improper storage, according to recent reports (1) (2), make up almost 25% of all chemical accidents. This relatively high percentage of chemical storage accidents suggests that these publications and color coding schemes although helpful, still provide incomplete information that may not completely mitigate storage risks. This manuscript will explore some ways published storage information may be incomplete, examine the associated risks, and suggest methods to help further eliminate chemical storage risks

  2. Control in the Chemical Industry

    Science.gov (United States)

    Jones, R. G.

    1974-01-01

    Discusses various control techniques used in chemical processes, including measuring devices, controller functions, control valves, and feedforward and feedback actions. Applications of control to a real chemical plant are exemplified. (CC)

  3. Tier II Chemical Storage Facilities

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — Facilities that store hazardous chemicals above certain quantities must submit an annual emergency and hazardous chemical inventory on a Tier II form. This is a...

  4. DECOLORIZATION AND CHEMICAL REGENERATION OF ...

    African Journals Online (AJOL)

    Preferred Customer

    Institute of Chemical Industry of Forest Products, CAF, Nanjing 210042, China ... of chemical method was an attractive economic factor. ... pharmaceutical industries. Today ... enzyme-treated starch. ... liquid, which increases production costs.

  5. Nigerian Journal of Chemical Research

    African Journals Online (AJOL)

    The Nigerian Journal of Chemical Research is now abstracted by Chemical Abstract Service (CAS). The journal's target is to communicate annually results of researchers in the broad areas of Chemistry, namely Analyitcal; Inorganic; Organic; Physical and other subdivisions of Chemistry.

  6. Chemical Agents: Facts about Evacuation

    Science.gov (United States)

    ... What CDC is Doing Blog: Public Health Matters Chemical Agents: Facts About Evacuation Format: Select One PDF [ ... on Facebook Tweet Share Compartir Some kinds of chemical accidents or attacks, such as a train derailment ...

  7. Computer simulation of chemical nucleation

    International Nuclear Information System (INIS)

    Turner, J.S.

    1979-01-01

    The problem of nucleation at chemical instabilities is investigated by means of microscopic computer simulation. The first-order transition of interest involves a new kind of nucleation arising from chemical transformations rather than physical forces. Here it is the chemical state of matter, and not matter itself, which is spatially localized to form the nucleus for transition between different chemical states. First, the concepts of chemical instability, nonequilibrium phase transition, and dissipative structure are reviewed briefly. Then recently developed methods of reactive molecular dynamics are used to study chemical nucleation in a simple model chemical reactions. Finally, the connection of these studies to nucleation and condensation processes involving physical and chemical interactions is explored. (orig.)

  8. Wiley guide to chemical incompatibilities

    National Research Council Canada - National Science Library

    Pohanish, Richard P; Greene, Stanley A

    2009-01-01

    .... A portable and easy-to-use reference on reactive substances commonly found in commerce, the Wiley Guide to Chemical Incompatibilities, Third Edition compiles hard-to-find data on over 11,000 chemical...

  9. Devices for collecting chemical compounds

    Science.gov (United States)

    Scott, Jill R; Groenewold, Gary S

    2013-12-24

    A device for sampling chemical compounds from fixed surfaces and related methods are disclosed. The device may include a vacuum source, a chamber and a sorbent material. The device may utilize vacuum extraction to volatilize the chemical compounds from a fixed surface so that they may be sorbed by the sorbent material. The sorbent material may then be analyzed using conventional thermal desorption/gas chromatography/mass spectrometry (TD/GC/MS) instrumentation to determine presence of the chemical compounds. The methods may include detecting release and presence of one or more chemical compounds and determining the efficacy of decontamination. The device may be useful in collection and analysis of a variety of chemical compounds, such as residual chemical warfare agents, chemical attribution signatures and toxic industrial chemicals.

  10. Chemical Weathering on Venus

    Science.gov (United States)

    Zolotov, Mikhail

    2018-01-01

    Chemical and phase compositions of Venus's surface could reflect history of gas- and fluid-rock interactions, recent and past climate changes, and a loss of water from the Earth's sister planet. The concept of chemical weathering on Venus through gas-solid type reactions has been established in 1960s after the discovery of hot and dense CO2-rich atmosphere inferred from Earth-based and Mariner 2 radio emission data. Initial works suggested carbonation, hydration, and oxidation of exposed igneous rocks and a control (buffering) of atmospheric gases by solid-gas type chemical equilibria in the near-surface lithosphere. Calcite, quartz, wollastonite, amphiboles, and Fe oxides were considered likely secondary minerals. Since the late 1970s, measurements of trace gases in the sub-cloud atmosphere by Pioneer Venus and Venera entry probes and Earth-based infrared spectroscopy doubted the likelihood of hydration and carbonation. The H2O gas content appeared to be low to allow a stable existence of hydrated and a majority of OH-bearing minerals. The concentration of SO2 was too high to allow the stability of calcite and Ca-rich silicates with respect to sulfatization to CaSO4. In 1980s, the supposed ongoing consumption of atmospheric SO2 to sulfates gained support by the detection of an elevated bulk S content at Venera and Vega landing sites. The induced composition of the near-surface atmosphere implied oxidation of ferrous minerals to magnetite and hematite, consistent with the infrared reflectance of surface materials. The likelihood of sulfatization and oxidation has been illustrated in modeling experiments at simulated Venus conditions. Venus's surface morphology suggests that hot surface rocks and fines of mainly mafic composition contacted atmospheric gases during several hundreds of millions years since a global volcanic resurfacing. Some exposed materials could have reacted at higher and lower temperatures in a presence of diverse gases at different altitudinal

  11. Chemical properties of mendelevium

    International Nuclear Information System (INIS)

    Hulet, E.K.

    1980-01-01

    The isotope 256 Md is nearly always employed for chemical studies of this element. This nuclide can be made by bombardment of fractions of a microgram of 254 Es with intense alpha-particle beams which will produce about 10 6 atoms of 256 Md with a half-life of 77 minutes. Even with the most intense ion beams and the largest available quantities of target isotope, about 10 6 atoms at a time is all the Md that can be produced for chemical studies. This lack of sufficient sample size coupled with the very short lifetimes of the few atoms produced has severly restricted the gathering and broadening of our knowledge concerning the properties of Md and the heavier elements. To illustrate, the literature contains a mere eleven references to the chemical studies of Md, and none of these deal with bulk properties associated with element found in solid phases. Some of these findings are: Md was found to be more volatile than other actinide metals which lead to the belief that it is divalent in the metallic state; separation of Md from the other actinides can be accomplished either by reduction of Md to the divalent state or by chromatographic separations with Md remaining in the tripositive state; extraction of Md with bis(2-ethylhexyl)phosphoric acid is much poorer than the extraction of the neighboring tripositive actinides; attempts to oxidize Md wih sodium bismuthate failed to show any evidence of Md 4+ ; standard reduction potential of Md 3+ was found to be close to -0.1 volt; Md 3+ can be reduced to Md(Hg) by sodium amalgams and by electrolysis; the electrochemical behavior of Md is very similar to that of Fm and can be summarized in the equation, Md 2+ + 2e - = Md(Hg), and E 0 = 1.5 V

  12. Chemical thermodynamics of uranium

    International Nuclear Information System (INIS)

    Grenthe, I.; Fuger, J.; Lemire, R.J.; Muller, A.B.; Nguyen-Trung Cregu, C.; Wanner, H.

    1992-01-01

    A comprehensive overview on the chemical thermodynamics of those elements that are of particular importance in the safety assessment of radioactive waste disposal systems is provided. This is the first volume in a series of critical reviews to be published on this subject. The book provides an extensive compilation of chemical thermodynamic data for uranium. A description of procedures for activity corrections and uncertainty estimates is given. A critical discussion of data needed for nuclear waste management assessments, including areas where significant gaps of knowledge exist is presented. A detailed inventory of chemical thermodynamic data for inorganic compounds and complexes of uranium is listed. Data and their uncertainty limits are recommended for 74 aqueous complexes and 199 solid and 31 gaseous compounds containing uranium, and on 52 aqueous and 17 solid auxiliary species containing no uranium. The data are internally consistent and compatible with the CODATA Key Values. The book contains a detailed discussion of procedures used for activity factor corrections in aqueous solution, as well as including methods for making uncertainty estimates. The recommended data have been prepared for use in environmental geochemistry. Containing contributions written by experts the chapters cover various subject areas such a s: oxide and hydroxide compounds and complexes, the uranium nitrides, the solid uranium nitrates and the arsenic-containing uranium compounds, uranates, procedures for consistent estimation of entropies, gaseous and solid uranium halides, gaseous uranium oxides, solid phosphorous-containing uranium compounds, alkali metal uranates, uncertainties, standards and conventions, aqueous complexes, uranium minerals dealing with solubility products and ionic strength corrections. The book is intended for nuclear research establishments and consulting firms dealing with uranium mining and nuclear waste disposal, as well as academic and research institutes

  13. LLNL Chemical Kinetics Modeling Group

    Energy Technology Data Exchange (ETDEWEB)

    Pitz, W J; Westbrook, C K; Mehl, M; Herbinet, O; Curran, H J; Silke, E J

    2008-09-24

    The LLNL chemical kinetics modeling group has been responsible for much progress in the development of chemical kinetic models for practical fuels. The group began its work in the early 1970s, developing chemical kinetic models for methane, ethane, ethanol and halogenated inhibitors. Most recently, it has been developing chemical kinetic models for large n-alkanes, cycloalkanes, hexenes, and large methyl esters. These component models are needed to represent gasoline, diesel, jet, and oil-sand-derived fuels.

  14. Stochastic processes in chemical physics

    CERN Document Server

    Shuler, K E

    2009-01-01

    The Advances in Chemical Physics series provides the chemical physics and physical chemistry fields with a forum for critical, authoritative evaluations of advances in every area of the discipline. Filled with cutting-edge research reported in a cohesive manner not found elsewhere in the literature, each volume of the Advances in Chemical Physics series serves as the perfect supplement to any advanced graduate class devoted to the study of chemical physics.

  15. HF/DF chemical labs

    International Nuclear Information System (INIS)

    Meinzer, R.A.

    1987-01-01

    This paper provides the essential details to understand and design HF/DF and related types of chemical lasers. The basic operation of the HF/DF chemical laser is described. The details of the excitation chemistry are presented and the pertinent laser physics is described. A description of the various laser components is given and the analytical models for the HF/DF chemical laser are discussed. A brief description of the chain reaction HF/DF chemical laser is offered

  16. Comparing chemical reaction networks

    DEFF Research Database (Denmark)

    Cardelli, Luca; Tribastone, Mirco; Tschaikowski, Max

    2017-01-01

    We study chemical reaction networks (CRNs) as a kernel model of concurrency provided with semantics based on ordinary differential equations. We investigate the problem of comparing two CRNs, i.e., to decide whether the solutions of a source and of a target CRN can be matched for an appropriate...... choice of initial conditions. Using a categorical framework, we extend and unify model-comparison approaches based on dynamical (semantic) and structural (syntactic) properties of CRNs. Then, we provide an algorithm to compare CRNs, running linearly in time with respect to the cardinality of all possible...... comparisons. Finally, using a prototype implementation, CAGE, we apply our results to biological models from the literature....

  17. Radiation chemical synthesis

    International Nuclear Information System (INIS)

    Zagoretz, P.A.; Poluetkov, V.A.; Shostenko, A.G.

    1986-01-01

    The authors consider processes in radiation chemical synthesis which are being developed in various scientific-research organizations. The important advantages of radiation chlorination, viz. the lower temperature compared with the thermal method and the absence of dehydrochlorination products are discussed. The authors examine the liquid-phase chlorination of trifluorochloroethyltrichloromethyl ether to obtain the pentachloro-contining ether, trifluorodichloroethyltrichloromethyl ether. The authors discuss radiation synthesis processes that have be used formulated kinetic equations on which models have been based. It is concluded that the possibilities of preparative (micro- and low-tonnage) radiation synthesis are promising

  18. Chemical evolution of galaxies

    International Nuclear Information System (INIS)

    Pagel, B.E.J.

    1990-01-01

    Initial conditions are probably set by results of Big Bang nucleosynthesis (BBNS) without intervening complications affecting the composition of visible matter so that extrapolation of observed abundances to BBNS products seems fairly secure. Primordial helium and deuterium abundances deduced in this way place upper and lower limits on baryonic density implying that both baryonic and non-baryonic dark matter exist and predicting no more than 3 neutrino flavours as recently confirmed in accelerator experiments. The validity of simple galactic chemical evolution models assumed in extrapolating back to the Big Bang is examined in the light of the frequency distribution of iron or oxygen abundances in the Galactic halo, bulge and disk. (orig.)

  19. Chemical degradation of pentachlorophenol

    International Nuclear Information System (INIS)

    Shukla, S.S.; Shukla, A.; Chandrasekharaiah, M.S.

    1992-01-01

    Industry produces a large volume of hazardous wastes containing pentachlorophenol, a U.S. EPA priority hazardous organic material. The environmentally safe disposal of these PCP-contaminated wastes is a serious problem for the waste management authorities as the current treatment processes are unsatisfactory. In this paper, the results of a feasibility study of chemical degradation and/or solidification methods for PCP-containing wastes. The photochemical decomposition of the PCP in a microemulsion or in micellar media obtained with the help of SDS or CTAB show the greatest promise

  20. On chemical potential

    International Nuclear Information System (INIS)

    Araki, H.

    1981-01-01

    In the framework of the C*-algebra formalism of quantum statistical mechanics, the concept of chemical potential or its vector generalization in the case of an arbitrary (not necessarily abelian) separable compact gauge group (of the first kind) is described as an algebraic label of equilibrium states at a given inverse temperature β. It is mathematically attained by extending a (clustering) KMS state of the gauge-invariant part of a C*-algebra F to a state of F and by examining the KMS property of the extension. (Auth.)