WorldWideScience

Sample records for high benzene concentrations

  1. Biodegradation of High Concentrations of Benzene Vapors in a Two Phase Partition Stirred Tank Bioreactor

    Directory of Open Access Journals (Sweden)

    Ali Karimi

    2013-01-01

    Full Text Available The present study examined the biodegradation rate of benzene vapors in a two phase stirred tank bioreactor by a bacterial consortium obtained from wastewater of an oil industry refinery house. Initially, the ability of the microbial consortium for degrading benzene was evaluated before running the bioreactor. The gaseous samples from inlet and outlet of bioreactor were directly injected into a gas chromatograph to determine benzene concentrations. Carbone oxide concentration at the inlet and outlet of bioreactor were also measured with a CO2 meter to determine the mineralization rate of benzene. Influence of the second non-aqueous phase (silicon oil has been emphasized, so at the first stage the removal efficiency (RE and elimination capacity (EC of benzene vapors were evaluated without any organic phase and in the second stage, 10% of silicon oil was added to bioreactor media as an organic phase. Addition of silicon oil increased the biodegradation performance up to an inlet loading of 5580?mg/m3, a condition at which, the elimination capacity and removal efficiency were 181?g/m3/h and 95% respectively. The elimination rate of benzene increased by 38% in the presence of 10% of silicone oil. The finding of this study demonstrated that two phase partition bioreactors (TPPBs are potentially effective tools for the treatment of gas streams contaminated with high concentrations of poorly water soluble organic contaminant, such as benzene.

  2. Biodegradation of high concentrations of benzene vapors in a two phase partition stirred tank bioreactor

    OpenAIRE

    Karimi Ali; Golbabaei Farideh; Neghab Masoud; Pourmand Mohammad Reza; Nikpey Ahmad; Mohammad Kazem; Mehrnia Momammad Reza

    2013-01-01

    Abstract The present study examined the biodegradation rate of benzene vapors in a two phase stirred tank bioreactor by a bacterial consortium obtained from wastewater of an oil industry refinery house. Initially, the ability of the microbial consortium for degrading benzene was evaluated before running the bioreactor. The gaseous samples from inlet and outlet of bioreactor were directly injected into a gas chromatograph to determine benzene concentrations. Carbone oxide concentration at the ...

  3. Estimating hourly benzene concentrations in a highly-complex topographical environment in northern Spain using RAMS and the CALPUFF modeling system

    Science.gov (United States)

    Valdenebro, Verónica; Sáez de Cámara, Estíbaliz; Gangoiti, Gotzon; Alonso, Lucio; García, José Antonio; Ilardia, Juan Luis; González, Nerea

    2013-04-01

    The RAMS-CALMET-CALPUFF modeling system together with observations has been used to analyse the hourly benzene impacts of a coke plant in a nearby urban area in a region of very complex topography (a mountainous region near the coast) in northern Spain. The air flow in this region is strongly influenced by the local topography and, specially under anticyclonic conditions, important daily changes in stability, wind velocity and wind direction occur almost every day, which directly affect the dispersion of pollutants in the area. The aim of this study was to set up a methodology suitable for dispersion studies in very complex areas, where pollutants dynamics is highly affected by mesoscale meteorological processes. Two ten-day periods have been modeled. High spatio-temporal resolution meteorological simulations have been performed with the non-hydrostatic mesoscale meteorological model RAMS. A configuration of four nested grids has been used. 4D assimilation has been performed using NCEP and ERA-Interim data. The RAMS meteorological output has been downscaled from a 1 km to a 250 m resolution with the CALMET diagnostic model. Observational meteorological data have been assimilated into CALMET. The results of the meteorological simulations have been validated both against data recorded by a network of surface stations and by a wind profiler radar (WPR) located near the coast. The already validated meteorological fields have been input into the CALPUFF nonsteady-state puff dispersion model. For the dispersion simulations, benzene emission data have been obtained from the Spanish E-PRTR Register. Predicted impacts have also been compared with observations. Comparisons of the RAMS simulated wind fields against the WPR profiles have revealed inaccurate NCEP reanalysis data for one of the simulated periods. Initialization with ECMWF-Interim data have improved the results. The main flows that affect dispersion in the area have been mostly well captured by the modeling system, for which the assimilation of meteorological observations into CALMET has shown of prime importance. This data assimilation has been crucial to reproduce the nocturnal drainage flows on some days and hence, for a subsequent simulation of the actual daily cycles of benzene concentrations by CALPUFF. These cycles has been captured by the model; however, concentration levels are underestimated, probably due to an underestimation of the registered benzene emissions. The availability of good meteorological observations in the area to assess the model reliability, and good emission data are of key importance to improve the model evaluations.

  4. Benzene from Traffic : Fuel Content and Ambient Air Concentrations

    DEFF Research Database (Denmark)

    Palmgren, F.; Berkowicz, R.

    2000-01-01

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

  5. Measurement of benzene concentration in urban air using passive sampling

    Energy Technology Data Exchange (ETDEWEB)

    Krol, Sylwia; Zabiegala, Bozena; Namiesnik, Jacek [Gdansk University of Technology (GUT), Department of Analytical Chemistry, Chemical Faculty, Gdansk (Poland)

    2012-05-15

    The concentration of benzene in urban air in the Tri-City area of Poland (Gdansk-Sopot-Gdynia, and Tczew) was assessed using diffusive passive samplers (Radiello). Samples were collected during a four-year monitoring campaign (2007-2010) at selected monitoring stations managed by the Agency of Regional Air Quality Monitoring in the Gdansk Metropolitan Area (ARMAAG) Foundation. The performance of the passive samplers was investigated in a field study that measured the benzene concentration in urban air. The results obtained by the Radiello samplers were compared with the results obtained using an on-line monitor (Chrompack CP 7001). Statistical analysis of the results obtained by the two different techniques (passive and on-line) was performed by a linear regression method (Student's t-test). The influence of temperature fluctuations on the uptake rate behavior of the passive samplers was also investigated. (orig.)

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

    Science.gov (United States)

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

    2014-05-01

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

  7. Concentrations of NO2, SO2, and benzene across Hanoi measured by passive diffusion samplers

    Science.gov (United States)

    Hien, P. D.; Hangartner, M.; Fabian, S.; Tan, P. M.

    2014-05-01

    The concentrations of NO2, SO2, and benzene were measured by passive diffusion samplers at 96 sites across Hanoi consisting of 80 sites in the inner city background, 6 traffic hot spots, 5 industry hot spots, and 5 rural sites. Two sampling campaigns were conducted in the winter and summer seasons of 2007, and the average concentration of the two campaigns was used as a proxy for the annual mean. The annual means of NO2, SO2, and benzene in the inner city background ranged from 17.9 to 65.9 ?g m-3, 11.7-47.4 ?g m-3, and 3.5 to 15.4 ?g m-3, respectively. The NO2/benzene and SO2 concentrations were higher at the traffic and industry hot spots, respectively. The background concentrations of NO2 and benzene tended to increase with the population density and were highest in crowded Hanoi downtown areas. These areas are facing high risks of violating the national legislation threshold for NO2 (40 ?g-3). The SO2 background concentrations were generally below the legislation threshold (50 ?g-3). Motorbikes, which dominate the Hanoi vehicle fleet, are the main polluters of NO2 and benzene, whereas SO2 comes mainly from diesel buses and trucks, except in some areas that are directly affected by industrial coal burning. Stringently regulating the exhaust emissions of vehicles, especially for motorbikes, and reducing the sulfur and benzene contents in fuels could be implemented to improve Hanoi's air quality.

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

    International Nuclear Information System (INIS)

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

  9. Biomarkers of exposure to low concentrations of benzene: a field assessment.

    OpenAIRE

    Johnson, E. S.

    1996-01-01

    OBJECTIVE: To carry out a comprehensive field investigation to evaluate various conventional and recently developed biomarkers for exposure to low concentrations of benzene. METHODS: Analyses were carried out on environmental air, unmetabolised benzene in blood and urine, urinary trans, transmuconic acid, and three major phenolic metabolites of benzene: phenol, catechol, and hydroquinone. Validations of these biomarkers were performed on 131 never smokers occupationally exposed to the time we...

  10. OH-initiated oxidation of benzene - Part II. Influence of elevated NOx concentrations

    DEFF Research Database (Denmark)

    Klotz, B; Volkamer, R

    2002-01-01

    The present work represents a continuation of part I of this series of papers, in which we investigated the phenol yields in the OH-initiated oxidation of benzene under conditions of low to moderate concentrations of NOx, to elevated NOx levels. The products of the OH-initiated oxidation of benzene in 700 760 Torr of N-2/O-2 diluent at 297 +/- 4 K were investigated in 3 different photochemical reaction chambers. In situ spectroscopic techniques were employed for the detection of products, and the initial concentrations of benzene, NOx, and O-2 were widely varied (by factors of 6300, 1500, and 13, respectively). In contrast to results from previous studies, a pronounced dependence of the product distribution on the NOx concentration was observed. The phenol yield decreases from approximately 50-60% in the presence of low concentrations (10 000 ppb) NOx concentrations. In the presence of high concentrations of NOx, the phenol yield increases with increasing O-2 partial pressure. The rate constant of the reaction of hydroxycyclohexadienyl peroxyl radicals with NO was determined to be (1.7 +/- 0.6) x 10(-11) cm(3) molecule(-1) s(-1). This reaction leads to the formation of E, E-2,4-hexadienedial as the main identiable product (29 +/- 16. The reaction of the hydroxycyclohexadienyl radical with NO2 gave phenol (5.9 +/- 3.4 and E,E-2,4-hexadienedial (3.4 +/- 1.9, no other products could be identified. The residual FTIR product spectra indicate the formation of unknown nitrates or other nitrogen-containing species in high yield. The results from the present work also show that experimental studies aimed at establishing/verifying chemical mechanisms for aromatic hydrocarbons must be performed using NOx levels which are representative of those found in the atmosphere.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-12-15

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

  12. Modeling annual benzene, toluene, NO2, and soot concentrations on the basis of road traffic characteristics

    International Nuclear Information System (INIS)

    The investigation of potential adverse health effects of urban traffic-related air pollution is hampered by difficulties encountered with exposure assessment. Usually public measuring sites are few and thereby do not adequately describe spatial variation of pollutant levels over an urban area. In turn, individual monitoring of pollution exposure among study subjects is laborious and expensive. We therefore investigated whether traffic characteristics can be used to adequately predict benzene, NO2, and soot concentrations at individual addresses of study subjects in the city area of Munich, Germany. For all road segments with expected traffic volumes of at least 4000 vehicles a day (n=1840), all vehicles were counted manually or a single weekday in 1995. The proportion of vehicles in 'stop-go' mode, n estimate of traffic jam, was determined. Furthermore, annual concentrations of benzene, NO2, and soot from 18 high-concentration sites means: 8.7, 65.8, and 12.9 ?g/m3, respectively) and from 16 school sites with moderate concentrations (means: 2.6, 32.2, and 5.7 ?g/m3, respectively) were measured from 1996 to 1998. Statistical analysis of the data was performed using components of two different statistical models recently used to predict air pollution levels in comparable settings. Two traffic characteristics, traffic volume and traffic jam percentage, adequately described air pollutant concentrations (R2: 0.76-0.8 concentrations (R2: 0.76-0.80, P=0.0001). This study shows that air pollutant concentrations can be accurately predicted by two traffic characteristics and that these models compare favorably with other more complex models in the literature

  13. Behavior of benzene and 1,3-butadiene concentrations in the urban atmosphere of Tokyo, Japan

    Science.gov (United States)

    Laowagul, Wanna; Yoshizumi, Kunio

    Benzene and 1,3-butadiene concentration profiles in the urban ambient air were generated to investigate their levels at two specified sampling locations, roadside and residential, in Tokyo, Japan. Air monitoring data for benzene and 1,3-butadiene were obtained from the Air Quality Monitoring Information of the Tokyo Metropolitan Government. Air samples were continuously obtained and analyzed every hour for volatile organic compounds (VOCs) using an automated GC-MS system. The diurnal variations in benzene and 1,3-butadiene concentrations showed bi-modal patterns, which were considered to be related to the increasing and decreasing trends of vehicle emissions and vertical mixing depths in a day. The frequencies of occurrence of various benzene and 1,3-butadiene concentrations were examined. The results of each concentration showed log-normal forms with almost straight lines. The frequency distributions of both pollutants were confirmed to have a log-normal, rather than a simple normal, form. The relationship between benzene and 1,3-butadiene concentrations at both the roadside and residential site were examined. Separate observations of day and night trends revealed that photochemical decomposition showed a greater influence on the data in the residential site than that in the roadside site. These results were considered as direct evidences of photochemical decomposition of 1,3-butadiene in the atmosphere.

  14. Concentrations of benzene and toluene in the atmosphere of the southwestern area at the Mexico City Metropolitan Zone

    Energy Technology Data Exchange (ETDEWEB)

    Bravo, H.; Sosa, R.; Sanchez, P. [Universidad Autonoma de Mexico, Ciudad Universitaria (Mexico). Centro de Ciencias de la Atmosfera; Bueno, E.; Gonzalez, L. [Centro Nacional de Investigacion y Capacitacion Ambiental, Instituto Nacional de Ecologia, SEMARNAP, Mexico (Mexico)

    2002-08-01

    The Mexico City Metropolitan Zone (MCMZ) presents important emissions of hazardous air pollutants. It is well documented that the MCMZ suffers a critical air pollution problem due to high ozone and particulate matter concentrations. However, toxic air pollutants such as benzene and toluene have not been considered. Benzene has accumulated sufficient evidence as a human carcinogen, and the ratio benzene/toluene is an excellent indicator to evaluate control strategies efficiency. In order to evaluate the levels of these two air toxic pollutants in the MCMZ, ambient air samples were collected in canisters and analyzed with a gas chromatograph with a flame ionization detector, according to procedures described in the United States Environmental Protection Agency (USEPA) method TO-15. Quality assurance was performed collecting duplicate samples which were analyzed in replicate to quantify the precision of air-quality measurements. Three different sites located in the Southwestern area in the MCMZ were selected for the sampling: the University campus, a gas station, and a vertical condominium area, in the same neighborhood, which presents different activities. At these sites, grab air samples were collected during the morning hours (7-8 a.m.), while for the University area, 24 h integrated air samples were collected simultaneously, with grab samples. Benzene concentrations (24 h sampling) in the atmosphere around the University campus have similar present levels as in other cities of North America. Mean values in this site were about 1.7 ppb. A significant variation exists between the benzene and toluene concentrations in the studied sites, being the more critical values than those registered at the gas station (an average of 25.8 ppb and a maximum of 141 ppb of benzene). There is a fuel regulation for gasoline in Mexico, which allows a maximum of 1 percent of benzene. However, since more than 60 percent of vehicles do not have catalytic converters (models before 1991) it is expected that most of this benzene be emitted through exhaust pipe. Another strategy being implemented is the use of vapor recovery systems at the gas stations. Vehicles emission control technology must be matched with adequate fuel characteristics in the problem area where it will be implemented, to achieve maximum emission reductions. (author)

  15. Quantitative relation of urinary phenol levels to breathzone benzene concentrations: a factory survey.

    OpenAIRE

    Inoue, O.; Seiji, K.; Kasahara, M.; Nakatsuka, H.; Watanabe, T.; Yin, S. G.; Li, G. L.; Jin, C.; Cai, S. X.; Wang, X. Z.

    1986-01-01

    Urine samples were collected from 64 men and 88 women in shoe factories and printing plants at the end of a seven hour day shift in the latter half of a week in spring. Urine samples were also taken from 43 men and 88 women in the same factories but who were not exposed to solvents. Exposure to benzene during the shift was monitored by passive dosimeters. Both phenol in urine and benzene in activated carbon were analysed with FID gas chromatographs. The urinary concentrations of phenol were l...

  16. A model to predict threshold concentrations for toxic effects of chlorinated benzenes in sediment

    Energy Technology Data Exchange (ETDEWEB)

    Fuchsman, P.C.; Duda, D.J.; Barber, T.R.

    1999-09-01

    A probabilistic model was developed to predict effects threshold concentrations for chlorinated benzenes in sediment. Based on published quantitative structure-activity relationships relating the toxicity of chlorinated benzenes to the degree of chlorination, congeners with the same number of chlorine substitutions were considered toxicologically equivalent. Hexachlorobenzene was excluded from the assessment based on a lack of aquatic toxicity at the water solubility limit. The equilibrium partitioning approach was applied in a probabilistic analysis to derive predicted effects thresholds (PETs) for each chlorinated benzene group, with model input distributions defined by published log K{sub ow} values and aquatic toxicity data extracted from the published literature. The probabilistic distributions of PETs generally increased with chlorination, with 20th percentile values ranging from 3.2 mg/kg{sub 1{degree}OC} for chlorobenzene to 67 mg/kg{sub 1%OC} for tetrachlorobenzene congeners. The toxicity of total chlorinated benzenes in sediment can be assessed by applying the PETs in a toxic index model, based on the assumption that multiple chlorinated benzene congeners will show approximately additive toxicity, as characteristic of nonpolar narcotic toxicants. The 20th percentile PET values are one to two orders of magnitude higher than published screening-level guidelines, suggesting that the screening-level guidelines will provide overly conservative assessments in most cases. Relevant spiked sediment toxicity data are very limited but seem consistent with the probabilistic model; additional testing could be conducted to confirm the model's predictions.

  17. Photoacoustic spectroscopy-based detector for measuring benzene and toluene concentration in gas and liquid samples

    International Nuclear Information System (INIS)

    Here we present a novel instrument for on-line, automatic measurement of benzene and toluene concentration in gas and liquid samples produced in the natural gas industry. Operation of the instrument is based on the collection of analytes on an adsorbent, separation using a chromatographic column and detection by near-infrared diode laser-based photoacoustic spectroscopy. Sample handling, measurement and data evaluation are carried out fully automatically, using an integrated, programmable electronic unit. The instrument was calibrated in the laboratory for natural gas, nitrogen and liquid glycol samples, and tested under field conditions at a natural gas dehydration unit of the MOL Hungarian Oil and Gas Company. Minimum detectable concentrations (3?m?1) were found to be 2.5 µg l?1 for benzene and 4 µg l?1 for toluene in gas samples, while 1.5 mg l?1 for benzene and 3 mg l?1 for toluene in liquid samples, which is suitable for measuring benzene and toluene concentration in natural gas and glycol samples occurring at natural gas dehydration plants

  18. Method of producing n-hexane and hexane concentrate by dearomatization of benzene fractions

    Energy Technology Data Exchange (ETDEWEB)

    Novansy, J.; Bucko, M.; Kopernicky, I.; Moravek, S.; Simko, K.; Zidek, Z.

    1982-05-30

    A method is patented for producing n-hexane and hexane concentrates by dearomatization of benzene fractions when content S is less than 20 ptm and a certain quantity of aromatic hydrocarbons and unsaturated hydrocarbons. To remove these hydrocarbons from the initial raw material (benzene fractions, reformed benzene fractions, hexane concentrates, raffinates from extraction of aromatic hydrocarbons, alkane concentrates from adsorption of n-alkanes in molecular sieves) it is subjected to hydrogenation of H/sub 2/ or H/sub 2/-containing gases with heterogeneous catalysts, which have hydrogenation, dehydrogenation activity and which contain metals of the VIII group of the periodic table, such as platinum or platinum containing bimetallic catalysts. Hydrogenation is conducted in one of several stages at temperature 50-400 /sup 0/, partial pressure of H/sub 2/ 100-20,000 kPa, volumetric speed of 0.1-15 hours/sup -1/ and quantity of H/sub 2/ of 1.5-150 times the predominant stoichiometric quantity. Hydrogenation can be done in fresh or repeatedly covered catalysts.

  19. Radiolysis ob benzene, toluene and phenol aqueous solutions utilizing high energy electron beam

    International Nuclear Information System (INIS)

    In a search for solutions to environmental pollution problems, radiolysis has proved to be an innovative technique for the removal of organic chemical pollutants in aqueous solution. Radiolysis has shown many advantages over many other techniques, as highly reactive species formed in water by ionizing radiation oxidize organic pollutants breaking down organic molecules to final simple products by oxidation to carbon dioxide and water in a complete oxidation. Our work consisted in doing some experiments in radiolysis with simulated polluted water to help us understand this technique and also develop, in a near future, a project for large scale water treatment. Our project includes the application of a Pelletron type Mexican made Electron Accelerator, which will affirm its capability and usefulness in performing investigation in this field of study. Experiments consisted in treating benzene, toluene and phenol aqueous solutions with an Electron Beam (0.48-0.55 MeV; 24 ?A). Two concentrations were used for each compound: 5 and 20 ppm (mg/l) for benzene and toluene; 10 and 50 ppm for phenol. Solutions were prepared with pure, mineral free water and two different p H (5.9), in order to study the effect of concentration and p H on removal efficiency, but avoiding the interference of radical scavengers. Results obtained coincide with the ones reported by Cooper, Nickelsen and Kurucz; highly efficient removal was achieved for benzene (>99.8%), toluene (>98.0%) and phenol (>88%). There was no visible important effect of p H on radiolysis efficiency for benzene nor toluene, phenol however, showed lower removal efficiency in acidic conditions. Concentration of aqueous solutions, nevertheless, did show an important effect at low doses for phenol. Results obtained reveal the importance of this technique in water pollution control and water remedial as expressed by Cooper, Nickelsen and Kurucz, who have studied radiolysis of organic compounds and apply this technique in water site remedial with a mobile Electron Beam facility. (Author)

  20. Quantitative detection of benzene in toluene- and xylene-rich atmospheres using high-kinetic-energy ion mobility spectrometry (IMS).

    Science.gov (United States)

    Langejuergen, Jens; Allers, Maria; Oermann, Jens; Kirk, Ansgar; Zimmermann, Stefan

    2014-12-01

    One major drawback of ion mobility spectrometry (IMS) is the dependence of the response to a certain analyte on the concentration of water or the presence of other compounds in the sample gas. Especially for low proton affine analytes, e.g., benzene, which often exists in mixtures with other volatile organic compounds, such as toluene and xylene (BTX), a time-consuming preseparation is necessary. In this work, we investigate BTX mixtures using a compact IMS operated at decreased pressure (20 mbar) and high kinetic ion energies (HiKE-IMS). The reduced electric field in both the reaction tube and the drift tube can be independently increased up to 120 Td. Under these conditions, the water cluster distribution of reactant ions is shifted toward smaller clusters independent of the water content in the sample gas. Thus, benzene can be ionized via proton transfer from H3O(+) reactant ions. Also, a formation of benzene ions via charge transfer from NO(+) is possible. Furthermore, the time for interaction between ions and neutrals of different analytes is limited to such an extent that a simultaneous quantification of benzene, toluene, and xylene is possible from low ppbv up to several ppmv concentrations. The mobility resolution of the presented HiKE-IMS varies from R = 65 at high field (90 Td) to R = 73 at lower field (40 Td) in the drift tube, which is sufficient to separate the analyzed compounds. The detection limit for benzene is 29 ppbv (2 s of averaging) with 3700 ppmv water, 12.4 ppmv toluene, and 9 ppmv xylene present in the sample gas. Furthermore, a less-moisture-dependent benzene measurement with a detection limit of 32 ppbv with ca. 21?000 ppmv (90% relative humidity (RH) at 20 °C) water present in the sample gas is possible evaluating the signal from benzene ions formed via charge transfer. PMID:25360539

  1. The impact of candle burning during All Saints' Day ceremonies on ambient alkyl-substituted benzene concentrations.

    Science.gov (United States)

    Olszowski, Tomasz; K?os, Andrzej

    2013-11-01

    Research findings concerning benzene, toluene, ethylobenzene, meta-, para- and ortho-xylene as well as styrene (BTEXS) emission at public cemeteries during All Saints' Day are presented here. Tests were carried out at town-located cemeteries in Opole and Grodków (southern Poland) and, as a benchmark, at the centres of those same towns. The purpose of the study was to estimate BTEXS emissions caused by the candle burning and, equally important to examine, whether emissions generated by the tested sources were similar to the BTEXS emissions generated by road transport. During the festive period, significant increases in benzene concentrations, by 200 % and 144 %, were noted at the cemeteries in Opole and Grodków, as well as in toluene, by 366 % and 342 %, respectively. Styrene concentrations also increased. It was demonstrated that the ratio of toluene to benzene concentrations from emissions caused by the burning candles are comparable to the ratio established for transportation emissions. PMID:24052143

  2. Determination of Benzene, Toluene and Xylene (BTX Concentrations in Air Using HPLC Developed Method Compared to Gas Chromatography

    Directory of Open Access Journals (Sweden)

    Abdulrahman Bahrami

    2011-01-01

    Full Text Available A new method for analysis of benzene, toluene, and xylene (BTX using High Performance Liquid Chromatography-UV detection (HPLC-UV is described and compared to the gas chromatography (GC method. A charcoal adsorption tube connected to a small pump was used to obtain samples from an atmosphere chamber standard. Samples were extracted with methanol and analyzed by HPLC-UV. Chromatography was isocratic in a mobile phase consisting of water-methanol (30-70. The flow rate was set at 1 ml/min. The analyses were completely separated and were quantified using both methods. The results demonstrated no statistically significant differences between BTX concentrations between the two analytical methods with a correlation coefficient of 0.98-0.99. The GC method provided higher sensitivity than HPLC, but the HPLC determination of BTX were applicable to real samples because its sensivity was lower than the thershold limit recommended by the American Conference of Governmental Industrial Hygienist (ACGIH for an 8-hour workday.

  3. Highly concentrating Fresnel lenses

    International Nuclear Information System (INIS)

    A new type of concave Fresnel lens capable of concentrating solar radiation very near the ultimate concentration limit is considered. The differential equations that describe the lens are solved to provide computed solutions which are then checked by ray tracing techniques. The performance (efficiency and concentration) of the lens is investigated and compared to that of a flat Fresnel lens, showing that the new lens is preferable for concentrating solar radiation. (author)

  4. High Dispersion Barium Sulfate Nanoparticles Prepared with Dodecyl Benzene Sulfonic Acid

    Science.gov (United States)

    Li, Ying; Wang, Xuanjun; Cui, Yibin; Ma, Wenxin; Guo, Heng

    2012-01-01

    Production of nanoparticles by precipitation is a relatively simple process but the control of product particle size distribution is difficult. In this paper, nanosize barium sulfate (BaSO4) particles are prepared with dodecyl benzene sulfonic acid (DBSA) in ethanol-water reaction system at room temperature. The BaSO4 nanoparticles are characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), powder X-ray diffraction (XRD), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FT-IR) and thermo gravimetric analysis (TGA), respectively. The results indicated that the average diameter of spherical BaSO4 is about 46 nm modified with 5 wt.% DBSA, which have good dispersion in the presence of a certain concentration NH3 ? H2O. It suggests that the high dispersion is attributed to presence of a thin layer of barium alkyl sulfate, which is formed and coated onto the surface of BaSO4 particles during the reaction process. The thin films on the surface of the BaSO4 effectively modified the surface and properties, which also control the particle size and morphology.

  5. Benzene emitted from glowing charcoal

    Energy Technology Data Exchange (ETDEWEB)

    Olsson, Maria; Petersson, Goran [Department of Chemical Environmental Science, Chalmers University of Technology, SE-412 96 Goteborg (Sweden)

    2003-03-01

    Benzene was assessed as the predominant aromatic compound emitted from glowing charcoal and firewood embers. Concentrations measured above charcoal used for grilling exceeded 10 mg m{sup -3} at a 5% carbon dioxide level. Charcoal with a high carbon content released less benzene. Glowing wood pellets emitted less benzene than glowing firewood remainders. The emissions of ethene and propene relative to benzene were low for commercial charcoal and wood-pellet embers, but high for firewood ember. The proportions of methylbenzene and naphthalene from charcoal were typically only 10% relative to benzene, and those of benzofuran, dibenzofuran and benzonitrile were typically below 5%. The polycyclic aromatic hydrocarbon (PAH) indicator phenanthrene was below the 1% level. Adsorbent sampling and GC-MS were used for assessing all the aromatic compounds. Earlier studies of charcoal emissions have focused on carbon monoxide, PAH and dioxins. It is concluded that the carcinogenic benzene may be an even more severe health hazard to be addressed by exposure-decreasing measures.

  6. Benzene emitted from glowing charcoal.

    Science.gov (United States)

    Olsson, Maria; Petersson, Göran

    2003-03-01

    Benzene was assessed as the predominant aromatic compound emitted from glowing charcoal and firewood embers. Concentrations measured above charcoal used for grilling exceeded 10 mg m(-3) at a 5% carbon dioxide level. Charcoal with a high carbon content released less benzene. Glowing wood pellets emitted less benzene than glowing firewood remainders. The emissions of ethene and propene relative to benzene were low for commercial charcoal and wood-pellet embers, but high for firewood ember. The proportions of methylbenzene and naphthalene from charcoal were typically only 10% relative to benzene, and those of benzofuran, dibenzofuran and benzonitrile were typically below 5%. The polycyclic aromatic hydrocarbon (PAH) indicator phenanthrene was below the 1% level. Adsorbent sampling and GC-MS were used for assessing all the aromatic compounds. Earlier studies of charcoal emissions have focused on carbon monoxide, PAH and dioxins. It is concluded that the carcinogenic benzene may be an even more severe health hazard to be addressed by exposure-decreasing measures. PMID:12606161

  7. Conversion of straight-run gas-condensate benzenes into high- octane gasolines based on modified ZSM-5 zeolites

    Science.gov (United States)

    Erofeev, V.; Reschetilowski, V.; Tatarkina, A.; Khomajakov, I.; Egorova, L.; Volgina, T.

    2014-08-01

    This paper describes the conversion of straight-run benzene of gas condensate into high-octane gasoline based on zeolite catalyst ZSM-5, modified in binary system oxide- based Sn (III) and Bi (III). It was defined that the introduction of the binary system oxide-based Sn(III) and Bi (III) into the basic zeolite results in the 2-fold increase of its catalytic activity.High-octane gasoline converted from straight-run benzene is characterized by a low benzol content in comparison to the high-octane benzenes produced during the catalytic reforming.

  8. Determination of Benzene, Toluene and Xylene (BTX) Concentrations in Air Using HPLC Developed Method Compared to Gas Chromatography

    OpenAIRE

    Abdulrahman Bahrami; Hosien Mahjub; Marzieh Sadeghian; Farideh Golbabaei

    2011-01-01

    A new method for analysis of benzene, toluene, and xylene (BTX) using High Performance Liquid Chromatography-UV detection (HPLC-UV) is described and compared to the gas chromatography (GC) method. A charcoal adsorption tube connected to a small pump was used to obtain samples from an atmosphere chamber standard. Samples were extracted with methanol and analyzed by HPLC-UV. Chromatography was isocratic in a mobile phase consisting of water-methanol (30-70). The flow rate was set at 1 ml/min. T...

  9. Retardation of biodegradation of linear alkyl benzene sulphonate by a sublethal concentration of mercuric chloride

    International Nuclear Information System (INIS)

    Environmental xenobiotics are usually classified into persistent and biodegradable ones. However, this may not be universally true, since biochemical capacity of ecosystems species may vary with species diversity and versatility. This may differ in different locations decided by geoclimatic factors. Prolonged exposure of organisms causing primary degradation to the toxic xenobiotics may lead to metabolic adaptation to survive the chemical stress. Also under multiple toxicant stress, the normal biodegrading capacity may be impaired by the effect of one toxicant on the organisms per se or on the enzymes causing degradation. If such inhibition of biodegradation occurs in ecosystems, even normally biodegradable chemicals may tend to accumulate. To test this view, model experiments were conducted with LAS (Linear alkyl benzene sulphonate) a biodegradable surfactant and mercuric chloride. Since the purpose of the study was to test the degradation under natural conditions, no attempt was made to identify the micro-organisms involved

  10. Occupational exposure to benzene in South Korea.

    Science.gov (United States)

    Kang, Seong-Kyu; Lee, Mi-Young; Kim, Tae-Kyun; Lee, Jeong-Oh; Ahn, Yeon Soon

    2005-05-30

    Benzene has been used in various industries as glues or solvents in Korea. Since 1981, a preparation containing more than 1% benzene is not allowed to be manufactured, used or dealt with in the workplace, except in laboratories and in those situations benzene must be used in a completely sealed process as specified in Industrial Safety and Health Act (ISHA). Claims for compensation of hematopoietic diseases related to benzene have been rising even though the work environment has been improved. This study was conducted to assess the status of benzene exposure in different industries in Korea. We reviewed the claimed cases investigated by the Korea Occupational Safety and Health Agency (KOSHA) between 1992 and 2000. The Survey of National Work Environment Status in 1998 was analyzed to assume the number of workers and factories exposed to benzene. In 2000, six factories were investigated to evaluate benzene exposure. Personal air monitoring was performed in 61 workers and urine samples were collected from 57 workers to measure trans,trans-muconic acid (t,t-MA). Hematologic examination has performed. Thirty-four cases of hematopoietic diseases were investigated by KOSHA including eight cases of myelodysplastic syndrome and eight cases of acute myelocytic leukemia. Eight cases were accepted as related to benzene exposure. The number of workers possibly exposed to benzene can be estimated to be 196,182 workers from 6219 factories based on the database. The geometric mean of benzene in air was 0.094 (0.005-5.311) ppm. Seven samples were higher than 1 ppm but they did not go over the 10 ppm occupational exposure limit (OEL) value in Korea. The geometric mean of trans,trans-muconic acid in urine was 0.966 (0.24-2.74) mg/g creatinine. The benzene exposure level was low except in a factory where benzene was used to polymerize other chemicals. The ambient benzene from 0.1 to 1 ppm was significantly correlated with urine t,t-MA concentration (r=0.733, p<0.01). Hematologic parameters did not show significant difference among groups divided into the level of exposure. Korean workers were not highly exposed to benzene and the level of exposure was mostly less than 1 ppm. However, there might be an excessive risk of hematopoietic disorders due to relatively high past exposure. The OEL value of benzene was amended to 1 ppm from 10 ppm in 2002 and was effective since July 2003. PMID:15935801

  11. Anaerobic benzene degradation by bacteria

    OpenAIRE

    Vogt, Carsten; Kleinsteuber, Sabine; Richnow, Hans?hermann

    2011-01-01

    Benzene is a widespread and toxic contaminant. The fate of benzene in contaminated aquifers seems to be primarily controlled by the abundance of oxygen: benzene is aerobically degraded at high rates by ubiquitous microorganisms, and the oxygen?dependent pathways for its breakdown were elucidated more than 50 years ago. In contrast, benzene was thought to be persistent under anoxic conditions until 25 years ago. Nevertheless, within the last 15 years, several benzene?degrading cultures hav...

  12. Evaluation of atmospheric benzene concentrations in the Helsinki Metropolitan Area in 2000-2003 using diffusive sampling and atmospheric dispersion modelling

    Science.gov (United States)

    Hellén, H.; Kukkonen, J.; Kauhaniemi, M.; Hakola, H.; Laurila, T.; Pietarila, H.

    Ambient air concentrations of benzene were both measured and predicted in the Helsinki Metropolitan area. Two-weekly measurements were conducted in 2000, 2002 and 2003 at seven measurement stations using diffusive adsorbent sampling; additional two-hourly measurements were also performed. An urban dispersion modelling system was utilised for modelling the spatial concentration distributions of benzene for 2000. According to both measurements and predictions, the annual mean benzene concentrations were below the upper assessment threshold (3.5 ?g m -3) set by the European Union, while the lower assessment threshold (2 ?g m -3) was exceeded at one urban station (Töölö) during the year 2000. The concentrations measured in the Helsinki Metropolitan Area were also compared with those at rural and remote stations in Finland. In the winters of 2000 and 2003, the concentrations at the remote and rural stations of Utö, Hyytiälä and Pallas were close to the concentrations at the urban background station of Kallio, while in the summers of 2000 and 2003, the concentrations at Kallio were substantially higher. The predicted concentrations in 2000 were highest in the vicinity of major roads and streets, and at their junctions. At all the stations, the predicted yearly averaged concentrations agreed fairly well with the measured data; the differences between measured and predicted values ranged from 10 to 31%. According to the measurements, and also the emission and dispersion computations, the most important source categories were exhaust emissions from local vehicular traffic, and the long-range transported background.

  13. SANS study of concentration effect in magnetite/oleic acid/benzene ferrofluid

    International Nuclear Information System (INIS)

    The effect of the colloidal particle concentration on the structure of the magnetite/C6D6 ferrofluid stabilized by oleic acid is investigated by small-angle neutron scattering (SANS). A significant decrease in the thickness of the surfactant layer with increase in the magnetite concentration is observed. This points to the fact that the interparticle interaction increasing with the concentration presses the surfactant tails in the layer closer against the magnetite surface. The influence of magnetic scattering on the SANS curves is considered. (orig.)

  14. Construction of a highly distorted benzene ring in a double helicene.

    Science.gov (United States)

    Hashimoto, Sigma; Nakatsuka, Soichiro; Nakamura, Masaharu; Hatakeyama, Takuji

    2014-12-15

    A P-fused double helicene consisting of a highly distorted benzene ring, with a bending angle of 23°, has been synthesized by a tandem intramolecular phospha-Friedel-Crafts reaction. Despite the distortion and reduced aromaticity, the double helicene shows thermal and chemical stability. These are important features that make these compounds attractive for applications as a new C2-symmetric bisphosphine ligand. The simple strategy proposed in this work can be used to prepare a diverse range of distorted molecules. PMID:25319613

  15. The benzene metabolite para-benzoquinone is genotoxic in human, phorbol-12-acetate-13-myristate induced, peripheral blood mononuclear cells at low concentrations.

    Science.gov (United States)

    Westphal, Götz Alexander; Bünger, Jürgen; Lichey, Nadine; Taeger, Dirk; Mönnich, Angelika; Hallier, Ernst

    2009-07-01

    Benzene is one of the most prominent occupational and environmental pollutants. The substance is a proven human carcinogen that induces hematologic malignancies in humans, probably at even low doses. Yet knowledge of the mechanisms leading to benzene-induced carcinogenesis is still incomplete. Benzene itself is not genotoxic. The generation of carcinogenic metabolites involves the production of oxidized intermediates such as catechol, hydroquinone and para-benzoquinone (p-BQ) in the liver. Further activation to the ultimate carcinogenic intermediates is most probably catalyzed by myeloperoxidase (MPO). Yet the products of the MPO pathway have not been identified. If an oxidized benzene metabolite such as p-BQ was actually the precursor for the ultimate carcinogenic benzene metabolite and further activation proceeds via MPO mediated reactions, it should be possible to activate p-BQ to a genotoxic compound in vitro. We tested this hypothesis with phorbol-12-acetate-13-myristate (PMA) activated peripheral blood cells exposed to p-BQ, using the cytokinesis-block micronucleus test. Addition of 20-28 ng/ml PMA caused a significant increase of micronuclei at low and non-cytotoxic p-BQ concentrations between 0.04 and 0.2 microg/ml (0.37-1.85 microM). Thus with PMA or p-BQ alone no reproducible elevation of micronuclei was seen up to toxic concentrations. PMA and p-BQ induce micronuclei when administered jointly. Our results add further support to the hypothesis that MPO is a key enzyme in the activation of benzene. PMID:19212761

  16. High concentration linear Fresnel reflectors

    International Nuclear Information System (INIS)

    Highlights: • Linear Fresnel reflectors (LFRs) have great potential for cost reductions. • Concentration in the receiver central strip as high as in trough collectors. • Daily constant flux map in the receiver if the filling factor is adequately designed. • High concentration variation between summer and winter for N–S configurations. - Abstract: The late exponential development of Concentrating Solar Power (CSP) technology has driven to a very high power installed worldwide, but with no time for global optimization of the technology. High feed-in-tariffs have concentrated investments on trough collectors and central towers, previously studied during the 1980s. Linear Fresnel reflectors (LFRs) are regarded as a low efficiency technology, which is mainly due to very little previous research. However, the use of slightly bent mirrors drives to high concentration ratios, with obvious cost advantages over other CSP technologies. This paper studies the radiation flux obtained in a flat receiver using different mirror shapes, and analyzes its variation along the year. Linear Fresnel reflector design variables are reviewed, and a Ray Tracing model of the Fresdemo prototype is carried out. Results show higher performances than expected

  17. Unusually high indoor radon concentrations

    International Nuclear Information System (INIS)

    Measurements of indoor radon concentrations in the village Umhausen (2600 inhabitants, Otzal valley, Tyrol, Austria) revealed unusually high indoor radon concentrations up to 274,000 Bq m-3. The medians measured on the basements were 3750 Bq m-3 in winter and 361 Bq m-3 in summer, those on the ground floors were 1180 Bq m-3 and 210 Bq m-3, respectively. Seventy-one per cent of the houses showed basement radon concentrations above the Austrian action level of 400 Bq m-3 in winter, 33% in summer. There are indications that the high radon concentrations are due to a giant rock slide about 8700 years ago. The unusually high radon concentration in Umhausen coincide with a statistically significant increase in lung cancer mortality. For the period 1970-1991 the age and sex standardized mortality rate is 3.85 (95% confidence interval: 2.9 to 5.1). The control population is the total population of Tyrol (630,000 inhabitants). (author)

  18. Neutron activation analysis of high purity nickel by solvent extraction using 2-benzylpyridin/benzene

    International Nuclear Information System (INIS)

    A radiochemical neutron activation analysis using solvent extraction has been applied for the determination of trace impurities in high purity nickel. Because of the high activity of 58Co produced by the nuclear reaction, 58Ni(n,p)58Co, cobalt should be separated from the impurities. Removal of cobalt from the other trace elements in the aqueous acidic solution containing 1M thiocyanate ion (KSCN-) was achieved by extraction with 1M 2-benzylpyridin (BPy) in benzene. From the result of tracer experiments, cobalt was completely separated from most other elements except Fe, Mo and Zn. To determine the experimental accuracy, NIST SRM 673 nickel oxide was analyzed and the results agreed well within 10% deviation. This established radiochemical method was applied to the analysis of high purity nickel samples. (author). 15 refs., 2 figs., 4 tabs

  19. Exposure to benzene and urinary concentrations of 8-hydroxydeoxyguanosine, a biological marker of oxidative damage to DNA.

    OpenAIRE

    Lagorio, S.; Tagesson, C.; Forastiere, F.; Iavarone, I.; Axelson, O.; Carere, A.

    1994-01-01

    OBJECTIVES--Benzene is an established animal and human carcinogen. The mechanism of benzene toxicity, particularly its leukaemogenic effect, is not fully understood. The modified base 8-hydroxy-deoxyguanosine (8-OHdG) is a sensitive marker of the DNA damage due to hydroxyl radical attack at the C8 of guanine. This damage, if left unrepaired, has been proposed to contribute to mutagenicity and cancer promotion. We conducted this biomonitoring study with the aim of evaluating the association be...

  20. Urinary t,t-muconic acid as an indicator of exposure to benzene.

    OpenAIRE

    Inoue, O.; Seiji, K.; Nakatsuka, H.; Watanabe, T.; Yin, S. N.; Li, G. L.; Cai, S. X.; Jin, C.; Ikeda, M.

    1989-01-01

    A method for rapidly determining t,t-muconic acid (MA) by high performance liquid chromatography was developed and successfully applied to urine samples from 152 workers exposed to benzene (64 men, 88 women) and 213 non-exposed controls (113 men, 100 women). The MA concentrations in urine correlated linearly with time weighted average benzene concentrations in the breath zone air of workers. A cross sectional balance study showed that about 2% of benzene inhaled is excreted into the urine as ...

  1. Benzene Oxidation Coupled to Sulfate Reduction

    OpenAIRE

    Lovley, D. R.; Coates, J. D.; Woodward, J. C.; Phillips, E.

    1995-01-01

    Highly reduced sediments from San Diego Bay, Calif., that were incubated under strictly anaerobic conditions metabolized benzene within 55 days when they were exposed initially to 1 (mu)M benzene. The rate of benzene metabolism increased as benzene was added back to the benzene-adapted sediments. When a [(sup14)C]benzene tracer was included with the benzene added to benzene-adapted sediments, 92% of the added radioactivity was recovered as (sup14)CO(inf2). Molybdate, an inhibitor of sulfate r...

  2. High level theoretical study of binding and of the potential energy surface in benzene–hydride system

    International Nuclear Information System (INIS)

    Graphical abstract: In-plane minimum geometries for benzene–H? non-covalent adducts: linear adduct (left) with the hydride ion hydrogen bonded to one aromatic hydrogen; bifurcated adduct (right), with the hydride ion hydrogen bonded to two adjacent aromatic hydrogens. Highlights: ? Theoretical study on covalent and non-covalent binding in benzene–hydride. ? Two non-covalent stable adducts were characterized in the in-plane geometry. ? Significant sections of the potential energy surface were determined. ? Formation of a very stable C6H7- anion upon covalent binding to carbon. - Abstract: High level ab initio calculations were performed on the interaction of the hydride anion with benzene, a system of potential interest for modelling the interactions occurring in hydrogen rich planetary atmospheres. We investigated both non-covalent and covalent binding, exploring the complete basis set limit using highly correlated MP2 and CCSD(T) levels of theory. Two non-covalent minima on the potential energy surface have been characterized, and found to correspond to moderately strong hydrogen bonding interactions. To gain further insight on the nature of binding, the total interaction energy was decomposed into its physically meaningful components and selected sections of the potential energy surface were calculated. Moreover, we found that H? can easily covalently bind to one of the carbon atoms of benzene tocarbon atoms of benzene to form a stable C6H7? anion, a global minimum on the potential energy surface, characterized by a puckered geometry, with a carbon atom bending out of the benzene plane. A slightly less stable planar C6H7? structure was also identified, corresponding to the transition state for the flipping motion of the puckered species.

  3. Benzene from catalytic hydrocracking

    Energy Technology Data Exchange (ETDEWEB)

    Cindric, M.

    1982-01-01

    The physiochemical and explosion properties of benzene, produced in the catalytic hydrocracking process at the Bosanski Brod petroleum refineries, were studied. The fractionation and group chemical composition of light (specific weight 0.6487) and heavy fractions (specific weight 0.7024) are given. The explosion characteristics are investigated together with the sensitivity to an injection of 6 grams explosion additives per one liter benzene. A heavy benzene fraction should be subjected to additional treatment in a catalytic reforming assembly. A variation in benzene's octane characteristics when compounded in a reformate of 10-40 percent light or heavy hydrocracking benzene fractions is studied. Graphs are designed which reflect an increase in the octane number of light (from 83 to 94) and heavy (from 63 to 80) benzene fractions when tetraethyllead (0.1-0.7 grams of lead to one liter of benzene) is injected. It is demonstrated that the hydrocracking catalytic process makes is possible to produce high quality benzene for carburator motors and a heavy fraction, which is a valuable raw material for hydrocracking catalytic assemblies.

  4. Health Risk Assessment of Ambient Air Concentrations of Benzene, Toluene and Xylene (BTX in Service Station Environments

    Directory of Open Access Journals (Sweden)

    Benjamin Edokpolo

    2014-06-01

    Full Text Available A comprehensive evaluation of the adverse health effects of human exposures to BTX from service station emissions was carried out using BTX exposure data from the scientific literature. The data was grouped into different scenarios based on activity, location and occupation and plotted as Cumulative Probability Distributions (CPD plots. Health risk was evaluated for each scenario using the Hazard Quotient (HQ at 50% (CEXP50 and 95% (CEXP95 exposure levels. HQ50 and HQ95 > 1 were obtained with benzene in the scenario for service station attendants and mechanics repairing petrol dispensing pumps indicating a possible health risk. The risk was minimized for service stations using vapour recovery systems which greatly reduced the benzene exposure levels. HQ50 and HQ95 < 1 were obtained for all other scenarios with benzene suggesting minimal risk for most of the exposed population. However, HQ50 and HQ95 < 1 was also found with toluene and xylene for all scenarios, suggesting minimal health risk. The lifetime excess Cancer Risk (CR and Overall Risk Probability for cancer on exposure to benzene was calculated for all Scenarios and this was higher amongst service station attendants than any other scenario.

  5. Health risk assessment of ambient air concentrations of benzene, toluene and xylene (BTX) in service station environments.

    Science.gov (United States)

    Edokpolo, Benjamin; Yu, Qiming Jimmy; Connell, Des

    2014-06-01

    A comprehensive evaluation of the adverse health effects of human exposures to BTX from service station emissions was carried out using BTX exposure data from the scientific literature. The data was grouped into different scenarios based on activity, location and occupation and plotted as Cumulative Probability Distributions (CPD) plots. Health risk was evaluated for each scenario using the Hazard Quotient (HQ) at 50% (CEXP50) and 95% (CEXP95) exposure levels. HQ50 and HQ95 > 1 were obtained with benzene in the scenario for service station attendants and mechanics repairing petrol dispensing pumps indicating a possible health risk. The risk was minimized for service stations using vapour recovery systems which greatly reduced the benzene exposure levels. HQ50 and HQ95 < 1 were obtained for all other scenarios with benzene suggesting minimal risk for most of the exposed population. However, HQ50 and HQ95 < 1 was also found with toluene and xylene for all scenarios, suggesting minimal health risk. The lifetime excess Cancer Risk (CR) and Overall Risk Probability for cancer on exposure to benzene was calculated for all Scenarios and this was higher amongst service station attendants than any other scenario. PMID:24945191

  6. The state of benzene in TIP slurry using nuclear magnetic resonance measurements

    International Nuclear Information System (INIS)

    Nuclear Magnetic Resonance (NMR) measurements on In-Tank Precipitation (ITP) simulated potassium tetraphenylborate (KTPB) slurries at Pacific Northwest National Laboratory have been completed. Most measurements were made on 4 wt percent KTPB slurry in 4 to 5 molar sodium salt solution. Liquid benzene was added volumetrically to the slurry in 25-mL vials and agitated to create a suspension. Earlier tests using dyed benzene showed that benzene remains suspended permanently in the slurry and the only visible change is overall slurry settling. Gentle vial agitation restores the original suspension state. To simulate in-situ uniformly dispersed benzene, benzene/KTPB samples were homogenized using a high speed rotor/stator biological homogenizer. Photomicrographs using homogenized samples containing dyed benzene showed no residual benzene droplets and fairly uniform coloration of the KTPB solids structure. All benzene concentration estimates are based on benzene addition since there is no available analytical method for benzene in slurry. Benzene losses could be significant, particularly at low concentrations and during homogenization

  7. Model for calculation of benzene and 1,3-butadiene concentrations in ambient air from geographic information, including biofuel burning and traffic; Modell foer beraekning av bensen- och 1,3-butadienhalter i omgivningsluft utifraan geografisk information om bland annat biobraensleeldning och trafik

    Energy Technology Data Exchange (ETDEWEB)

    Modig, Lars; Hagenbjoerk-Gustafsson, Annika; Jonsson, Lennart; Olsson, David; Forsberg, Bertil [Umeaa Univ., Faculty of Medicine, Dept. of Public Health and Clinical Medicine, Occupational and Environmental Medicine, Umeaa (Sweden); Stroemgren, Magnus [Umeaa Univ., Faculty of Social Sciences, Dept. of Geography and Economic History, Umeaa (Sweden)

    2012-07-01

    The aim of the project was to apply a type of statistical calculation model, 'Land Use Regression (LUR)', to predict the concentrations of air pollutants benzene and 1,3-butadiene in a number of urban areas with a high proportion of small-scale biofuel burning in and around Umeaa.

  8. High selectivity of benzene electrochemical oxidation to p-benzoquinone on modified PbO2 electrode

    Science.gov (United States)

    Li, Xiaolin; Li, Xueming; Tang, Sui; Yang, Jianchun; Li, Wulin; Luo, Binbin; Yu, Yajiao; Li, Shanya

    2014-08-01

    In this paper, a modified Ti/SnO2-Sb2O3/PbO2 electrode was successfully synthesized. The interlayer SnO2-Sb2O3 was obtained through thermal decomposition and the surface layer by electrochemical deposition. The structures and morphology of the layers were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical property was carried out by cyclic voltammogrametry (CV) and the products obtained from electrochemical oxidation of benzene were investigated by gas chromatography and mass spectrometry (GC-MS). The results showed that the surface of the prepared electrode was mainly composed of tetragonal-shaped ?-PbO2 crystal with a pyramidal-angular structure. The oxidation potential of benzene was +1.8 V vs. Ag/AgCl. The electrochemical oxidation of benzene showed the high selectivity toward p-benzoquinone on the modified Ti/SnO2-Sb2O3/PbO2 electrode. And the optimal oxidation temperature for oxidation of benzene was 75 °C and the optimal temperature was 60 min.

  9. High level theoretical study of binding and of the potential energy surface in benzene-hydride system

    Energy Technology Data Exchange (ETDEWEB)

    Coletti, Cecilia, E-mail: ccoletti@unich.it [Dipartimento di Scienze del Farmaco, Universita ' G. d' Annunzio' Chieti-Pescara, Via dei Vestini 31, 66100 Chieti (Italy); Re, Nazzareno [Dipartimento di Scienze del Farmaco, Universita ' G. d' Annunzio' Chieti-Pescara, Via dei Vestini 31, 66100 Chieti (Italy)

    2012-04-04

    Graphical abstract: In-plane minimum geometries for benzene-H{sup -} non-covalent adducts: linear adduct (left) with the hydride ion hydrogen bonded to one aromatic hydrogen; bifurcated adduct (right), with the hydride ion hydrogen bonded to two adjacent aromatic hydrogens. Highlights: Black-Right-Pointing-Pointer Theoretical study on covalent and non-covalent binding in benzene-hydride. Black-Right-Pointing-Pointer Two non-covalent stable adducts were characterized in the in-plane geometry. Black-Right-Pointing-Pointer Significant sections of the potential energy surface were determined. Black-Right-Pointing-Pointer Formation of a very stable C{sub 6}H{sub 7}{sup -} anion upon covalent binding to carbon. - Abstract: High level ab initio calculations were performed on the interaction of the hydride anion with benzene, a system of potential interest for modelling the interactions occurring in hydrogen rich planetary atmospheres. We investigated both non-covalent and covalent binding, exploring the complete basis set limit using highly correlated MP2 and CCSD(T) levels of theory. Two non-covalent minima on the potential energy surface have been characterized, and found to correspond to moderately strong hydrogen bonding interactions. To gain further insight on the nature of binding, the total interaction energy was decomposed into its physically meaningful components and selected sections of the potential energy surface were calculated. Moreover, we found that H{sup -} can easily covalently bind to one of the carbon atoms of benzene to form a stable C{sub 6}H{sub 7}{sup -} anion, a global minimum on the potential energy surface, characterized by a puckered geometry, with a carbon atom bending out of the benzene plane. A slightly less stable planar C{sub 6}H{sub 7}{sup -} structure was also identified, corresponding to the transition state for the flipping motion of the puckered species.

  10. The diffusion of benzene in high silica zeolite ZSM5 studied by PFGNMR and QUENS

    International Nuclear Information System (INIS)

    The diffusion of benzene in the high silica zeolite ZSM5 has been studied at various coverages by pulsed filed gradient nuclear magnetic resonance (PDGNMR) and quasi-elastic neutron scattering (QUENS). The PFGNMR technique has probed inter- and intra-crystalline diffusion over the milisecond timescale giving intracoefficients of the order 10-10 m2 s-1 and inter coefficients in the range from 10-7 to 10-9 m2 s-1 with increasing coverage. This suggests a 'viscous'liquid-like environment inside the zeolite but rather faster diffusion between crystallites. QUENS has probed intra-crystalline diffusion on the nanosecond timescale giving results in the range 10-10 to 10-9 m2 s-1 at high coverages. A jump activation energy for this process of 5.5+-0.4 kJ mol-1 has been estimated over the temperature range of 213 to 343K. (author). 23 refs.; 8 figs.; 3 tabs

  11. Irreversible sorption of benzene in sandy aquifer materials

    Science.gov (United States)

    Baek, Doo-Sung; Kim, Song-Bae; Kim, Dong-Ju

    2003-04-01

    Hydrocarbon compounds in aquifers are generally known to show a retardation effect due to sorption onto the surfaces of solid particles. In this study, we investigated the effect of sorption on the transport of benzene in sandy aquifer materials by conducting batch and column tests for both sandy aquifer materials and sandy materials to which had been added 0·5% powdered activated carbon. The batch test was conducted by equilibrating dry materials with benzene solutions of various initial concentrations, and by analysing the concentrations of benzene in the initial and equilibrated solutions using high-performance liquid chromatography (HPLC). The column test was performed to monitor the concentrations of effluent versus time, known as a breakthrough curve (BTC). We injected KCl and benzene solutions as tracers into the inlet boundary as two different types of square pulse and step, and monitored the effluent concentrations at the exit boundary under a steady-state condition using an electrical conductivity meter and HPLC. Simulation of benzene transport was performed using the convective-dispersive equation model with the distribution coefficients obtained from the batch test and the transport parameters of the conservative solute KCl from the column test. The observed BTCs of KCl and benzene for pulse injection showed that the arrival times of the peaks of both tracers coincided well, but the relative peak concentration of benzene was much lower than that of KCl. Comparison of the simulated and observed BTCs showed a great discrepancy for all cases of injection mode and material texture, indicating the absence of retardation effect. These results reveal that the predominant process affecting the benzene transport in the sandy aquifer materials is an irreversible sorption rather than retardation. This tentative conclusion was verified by simulation of benzene transport using an irreversible sorption parameter that led to a good agreement between the simulated and observed BTCs.

  12. The Impact of Candle Burning During All Saints’ Day Ceremonies on Ambient Alkyl-Substituted Benzene Concentrations

    OpenAIRE

    Olszowski, Tomasz; K?os, Andrzej

    2013-01-01

    Research findings concerning benzene, toluene, ethylobenzene, meta-, para- and ortho-xylene as well as styrene (BTEXS) emission at public cemeteries during All Saints’ Day are presented here. Tests were carried out at town-located cemeteries in Opole and Grodków (southern Poland) and, as a benchmark, at the centres of those same towns. The purpose of the study was to estimate BTEXS emissions caused by the candle burning and, equally important to examine, whether emissions generated by the ...

  13. Quantitation of urinary metabolites of toluene, xylene, styrene, ethylbenzene, benzene and phenol by automated high performance liquid chromatography.

    Science.gov (United States)

    Ogata, M; Taguchi, T

    1987-01-01

    An automated high performance liquid chromatographic method (HPLC) for the direct determination of urinary concentrations of hippuric acid (HA), and o-, m- and p-methyl hippuric acids (MHAs), metabolites of toluene and o-, m-, and p-xylenes, and of urinary phenyl glyoxylic acid (PGA) and mandelic acid (MA), metabolites of styrene or ethylbenzene, is described. Methanol was added to urine, the mixture was centrifuged and the supernatant was injected into HPLC. A stainless-steel column packed with octadecyl silanized silicate was used and the mobile phase was a mixed solution of 5 mM potassium phosphate monobasic/acetonitrile (90/10). The method is simple and specific. Urine can be analyzed without solvent extraction. Analysis can be performed satisfactorily within 45 min for samples containing HA, MHAs, PGA and MA, and within 15 min for those containing HA, PGA and MA. Another automated HPLC method for the determination of urinary concentrations of phenylsulfate (PhS) and phenylglucuronide (PhG), metabolites of benzene and phenol, is also described. Urine was centrifuged and the supernatant was injected into HPLC. A column packed with octadecyl silicate and a mobile phase of 50 mM of potassium phosphate monobasic/acetonitrile (85/15) were used. The whole analyses and quantitative determination can be performed within 15 min for samples containing PhS and PhG in the worker's urine with a simple mobile phase. The accuracy and precision in the present methods by the use of automated HPLC were satisfactory. PMID:3570490

  14. Human Benzene Metabolism Following Occupational and Environmental Exposures

    OpenAIRE

    Rappaport, S. M.; Kim, S.; Lan, Q.; Li, G.; Vermeulen, R.; Waidyanatha, S.; Zhang, L.; Yin, S.; Smith, M. T.; Rothman, N.

    2009-01-01

    We previously reported evidence that humans metabolize benzene via two enzymes, including a hitherto unrecognized high-affinity enzyme that was responsible for an estimated 73 percent of total urinary metabolites [sum of phenol (PH), hydroquinone (HQ), catechol (CA), E,E-muconic acid (MA), and S-phenylmercapturic acid (SPMA)] in nonsmoking females exposed to benzene at sub-saturating (ppb) air concentrations. Here, we used the same Michaelis-Menten-like kinetic models to individually analyze ...

  15. S-phenylcysteine in albumin as a benzene biomarker.

    OpenAIRE

    Bechtold, W. E.; Strunk, M. R.

    1996-01-01

    Biological markers of internal dose are useful for improving the extrapolation of health effects from exposures to high levels of toxic air pollutants in animals to low, ambient exposures in humans. Previous results from our laboratory have shown that benzene is metabolized by humans to form the adduct S-phenylcysteine (SPC). Levels of SPC measured in humans occupationally exposed to benzene were increased linearly relative to exposure concentrations ranging from 0 to 23.1 ppm for 8 hr/day, 5...

  16. Determination of catechol and quinol in the urine of workers exposed to benzene.

    OpenAIRE

    Inoue, O.; Seiji, K.; Kasahara, M.; Nakatsuka, H.; Watanabe, T.; Yin, S. G.; Li, G. L.; Cai, S. X.; Jin, C.; Ikeda, M.

    1988-01-01

    Time weighted average concentrations of benzene in breathing zone air (measured by diffusive sampling coupled with FID gas chromatography) and concentrations of catechol and quinol in the urine (collected at about 1500 in the second half of a working week and analysed by high performance liquid chromatography) were compared in 152 workers who were exposed to benzene (64 men, 88 women). The concentration of urinary metabolites was also determined in 131 non-exposed subjects (43 men, 88 women)....

  17. Evaluation of biomarkers for occupational exposure to benzene.

    OpenAIRE

    Ong, C. N.; Kok, P. W.; Lee, B. L.; Shi, C. Y.; Ong, H. Y.; Chia, K. S.; Lee, C. S.; Luo, X. W.

    1995-01-01

    OBJECTIVE--To evaluate the relations between environmental benzene concentrations and various biomarkers of exposure to benzene. METHODS--Analyses were carried out on environmental air, unmetabolised benzene in urine, trans, trans-muconic acid (ttMA), and three major phenolic metabolites of benzene; catechol, hydroquinone, and phenol, in two field studies on 64 workers exposed to benzene concentrations from 0.12 to 68 ppm, the time weighted average (TWA). Forty nonexposed subjects were also i...

  18. Modeling the natural attenuation of benzene in groundwater impacted by ethanol-blended fuels: Effect of ethanol content on the lifespan and maximum length of benzene plumes

    Science.gov (United States)

    Gomez, Diego E.; Alvarez, Pedro J. J.

    2009-03-01

    A numerical model was used to evaluate how the concentration of ethanol in reformulated gasoline affects the length and longevity of benzene plumes in fuel-contaminated groundwater. Simulations considered a decaying light nonaqueous phase liquid source with a total mass of ˜85 kg and a groundwater seepage velocity of 9 cm d-1 and corroborated previous laboratory, field, and modeling studies showing benzene plume elongation due to the presence of ethanol. Benzene plume elongation reached a maximum of 59% for 20% ethanol content (E20) relative to regular gasoline without ethanol. Elongation was due to accelerated depletion of dissolved oxygen during ethanol degradation and to a lower specific rate of benzene utilization caused by metabolic flux dilution and catabolite repression. The lifespan of benzene plumes was shorter for all ethanol blends compared to regular gasoline (e.g., 17 years for regular gasoline, 15 years for E10, 9 years for E50, and 3 years for E85), indicating greater natural attenuation potential for higher-ethanol blends. This was attributed to a lower mass of benzene released for higher-ethanol blends and increased microbial activity associated with fortuitous growth of benzene degraders on ethanol. Whereas site-specific conditions will determine actual benzene plume length and longevity, these decaying-source simulations imply that high-ethanol blends (e.g., E85) pose a lower risk of benzene reaching a receptor via groundwater migration than low-ethanol blends such as E10.

  19. Development of a biphasic electroreactor with a wet scrubbing system for the removal of gaseous benzene.

    Science.gov (United States)

    Govindan, Muthuraman; Chung, Sang Joon; Moon, Hyun-Ho; Jang, Jae Wook; Moon, Il-Shik

    2013-08-12

    An efficient, continuous flow electroreactor system comprising a scrubbing column (for absorption) and a biphasic electroreactor (for degradation) was developed to treat gas streams containing benzene. Initial benzene absorption studies using a continuous flow bubble column containing absorbents like 40% sulfuric acid, 10% silicone oil (3, 5, 10 cSt), or 100% silicone oil showed that 100% silicone oil is the most suitable. A biphasic batch electroreactor based on 50 mL of silicone oil and 100 mL of activated Co(III) (activated electrochemically) in 40% sulfuric acid demonstrated that indirect oxidation of benzene is possible by Co(III). Combined experiments on the wet scrubbing column and biphasic electroreactor (BP-ER) were performed to determine the feasibility of benzene removal, which is reside in the silicone oil medium. In semidynamic scrubbing with BP-ER experiments using an aqueous electroreactor volume of 2 L, and an inlet gas flow and a gaseous benzene concentration were 10 Lmin(-1) and 100 ppm, respectively, benzene removal efficiency is 75% in sustainable way. The trend of CO2 evolution is well correlated with benzene recovery in the BP-ER. The addition of sodiumdodecyl sulfate (SDS) enhanced the recovery of silicone oil without affecting benzene removal. This process is promising for the treatment of high concentrations of gaseous benzene. PMID:23883273

  20. Design and development of a high-concentration photovoltaic concentrator

    Energy Technology Data Exchange (ETDEWEB)

    Hodge, R C

    1982-04-01

    The design and development of a high concentration photovoltaic concentrator module is discussed. The design concept described herein incorporates a curved groove domed Fresnel lens, a high concentration etched multiple vertical junction (EMVJ) solar cell and a passively cooled direct-bonded copper cell mount all packaged in a plastic module. Two seven inch diameter 1200x domed Fresnel lenses were fabricated using single point diamond turning technology. Testing at both GE and Sandia confirmed optical transmission efficiencies of over 83%. Samples of the latest available EMVJ cells were mounted and installed, with a domed Fresnel lens, into a prototype module. Subsequent testing demonstrated net lens-cell efficiencies of 10 to 13%. As a result of this program, salient conclusions have been formulated as to this technology.

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

    International Nuclear Information System (INIS)

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

  2. Occupational exposure to benzene in China.

    OpenAIRE

    Yin, S. N.; Li, Q.; Liu, Y.; Tian, F.; Du, C.; Jin, C.

    1987-01-01

    Of a total of 528,729 workers exposed to benzene or benzene mixtures in China, 508,818 (96.23%) were examined. Altogether 2,676 cases of benzene poisoning were found, a prevalence of 0.15%. A higher prevalence of benzene poisoning was found in the cities of Hangjou, Hefei, Nanjing, Shenyang, and Xian. The geometric mean concentration of benzene in 50,255 workplaces was 18.1 mg/m3 but 64.6% of the workplaces had less than 40 mg/m3. There was a positive correlation between the prevalence of ben...

  3. The benzene metabolite para-benzoquinone is genotoxic in human, phorbol-12-acetate-13-myristate induced, peripheral blood mononuclear cells at low concentrations

    OpenAIRE

    Westphal, Go?tz Alexander; Bu?nger, Ju?rgen; Lichey, Nadine; Taeger, Dirk; Mo?nnich, Angelika; Hallier, Ernst

    2009-01-01

    Benzene is one of the most prominent occupational and environmental pollutants. The substance is a proven human carcinogen that induces hematologic malignancies in humans, probably at even low doses. Yet knowledge of the mechanisms leading to benzene-induced carcinogenesis is still incomplete. Benzene itself is not genotoxic. The generation of carcinogenic metabolites involves the production of oxidized intermediates such as catechol, hydroquinone and para-benzoquinone (p-BQ) in the liver. Fu...

  4. Pulsed-field ionization spectroscopy of high Rydberg states (n=50-200) of bis(?6-benzene)chromium

    Science.gov (United States)

    Choi, Kyo-Won; Choi, Sunyoung; Baek, Sun Jong; Kim, Sang Kyu

    2007-01-01

    The ionization behavior of the high Rydberg states of bis(?6-benzene)chromium in the presence of ac and/or dc fields has been explored. The application of an ac scrambling field at the time of laser excitation lengthens the lifetime of the Rydberg state by almost two orders of magnitude. The lifetime enhancement by the scrambling field is much more effective for n 100 Rydberg states. The pulsed-field ionization of Rydberg states of n IP =5.4665±0.0003eV. Optimization of the various electric field conditions greatly enhances the spectral sensitivity of the mass-analyzed threshold ionization (MATI) spectroscopy. The high-resolution MATI spectrum of the title molecule obtained here provides precise cationic vibrational frequencies for many skeletal and benzene ring modes. A number of vibrational modes are newly identified, and the ambiguity regarding to some mode assignments is now clearly resolved through the Frank-Condon analysis based on ab initio calculations.

  5. Synthesis of highly phosphonic acid functionalized benzene-bridged periodic mesoporous organosilicas for use as efficient dye adsorbents.

    Science.gov (United States)

    Deka, Juti Rani; Liu, Chia-Ling; Wang, Tzu-Hua; Chang, Wei-Chieh; Kao, Hsien-Ming

    2014-08-15

    Periodic mesoporous organosilicas (PMOs) with benzene bridging groups in the silica wall were functionalized with a tunable content of phosphonic acid groups. These bifunctional materials were synthesized by co-condensation of two different organosilane precursors, that is, 1,4-bis(triethoxysilyl)benzene (BTEB) and sodium 3-(trihydroxysilyl)propyl methyl phosphate (SPMP), under acidic conditions using nonionic surfactant Brij-S10 as template. The materials exhibited well-ordered mesostructures and were characterized by X-ray diffraction, nitrogen sorption, TEM, TGA, FTIR, and solid-state NMR measurements. The materials thus obtained were employed as adsorbents to remove different types of dyes, for example, cationic dyes methylene blue and phenosafranine, anionic orange II, and amphoteric rhodamine B, from aqueous solutions. The materials exhibited a remarkably high adsorption capacity than activated carbon due to their ordered mesostructures, a large number of phosphonic acid groups, and high surface areas. The adsorption was mainly governed by electrostatic interaction, but also involved ?-? stacking interaction as well as hydrogen bonding. The adsorption kinetics can be better fitted by the pseudo-second order model. The adsorption process was controlled by the mechanisms of external mass transfer and intraparticle diffusion. The materials retained more than 97% dye removal efficiency after use for five consecutive cycles. PMID:25010459

  6. Fuel Dependence of Benzene Pathways

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, H; Eddings, E; Sarofim, A; Westbrook, C

    2008-07-14

    The relative importance of formation pathways for benzene, an important precursor to soot formation, was determined from the simulation of 22 premixed flames for a wide range of equivalence ratios (1.0 to 3.06), fuels (C{sub 1}-C{sub 12}), and pressures (20 to 760 torr). The maximum benzene concentrations in 15 out of these flames were well reproduced within 30% of the experimental data. Fuel structural properties were found to be critical for benzene production. Cyclohexanes and C{sub 3} and C{sub 4} fuels were found to be among the most productive in benzene formation; and long-chain normal paraffins produce the least amount of benzene. Other properties, such as equivalence ratio and combustion temperatures, were also found to be important in determining the amount of benzene produced in flames. Reaction pathways for benzene formation were examined critically in four premixed flames of structurally different fuels of acetylene, n-decane, butadiene, and cyclohexane. Reactions involving precursors, such as C{sub 3} and C{sub 4} species, were examined. Combination reactions of C{sub 3} species were identified to be the major benzene formation routes with the exception of the cyclohexane flame, in which benzene is formed exclusively from cascading fuel dehydrogenation via cyclohexene and cyclohexadiene intermediates. Acetylene addition makes a minor contribution to benzene formation, except in the butadiene flame where C{sub 4}H{sub 5} radicals are produced directly from the fuel, and in the n-decane flame where C{sub 4}H{sub 5} radicals are produced from large alkyl radical decomposition and H atom abstraction from the resulting large olefins.

  7. Highly selective GaN-nanowire/TiO2-nanocluster hybrid sensors for detection of benzene and related environment pollutants.

    Science.gov (United States)

    Aluri, Geetha S; Motayed, Abhishek; Davydov, Albert V; Oleshko, Vladimir P; Bertness, Kris A; Sanford, Norman A; Rao, Mulpuri V

    2011-07-22

    Nanowire-nanocluster hybrid chemical sensors were realized by functionalizing gallium nitride (GaN) nanowires (NWs) with titanium dioxide (TiO(2)) nanoclusters for selectively sensing benzene and other related aromatic compounds. Hybrid sensor devices were developed by fabricating two-terminal devices using individual GaN NWs followed by the deposition of TiO(2) nanoclusters using RF magnetron sputtering. The sensor fabrication process employed standard microfabrication techniques. X-ray diffraction and high-resolution analytical transmission electron microscopy using energy-dispersive x-ray and electron energy-loss spectroscopies confirmed the presence of the anatase phase in TiO(2) clusters after post-deposition anneal at 700?°C. A change of current was observed for these hybrid sensors when exposed to the vapors of aromatic compounds (benzene, toluene, ethylbenzene, xylene and chlorobenzene mixed with air) under UV excitation, while they had no response to non-aromatic organic compounds such as methanol, ethanol, isopropanol, chloroform, acetone and 1,3-hexadiene. The sensitivity range for the noted aromatic compounds except chlorobenzene were from 1% down to 50 parts per billion (ppb) at room temperature. By combining the enhanced catalytic properties of the TiO(2) nanoclusters with the sensitive transduction capability of the nanowires, an ultra-sensitive and selective chemical sensing architecture is demonstrated. We have proposed a mechanism that could qualitatively explain the observed sensing behavior. PMID:21673385

  8. Highly concentrated foam formulation for blast mitigation

    Science.gov (United States)

    Tucker, Mark D. (Albuquerque, NM); Gao, Huizhen (Albuquerque, NM)

    2010-12-14

    A highly concentrated foam formulation for blast suppression and dispersion mitigation for use in responding to a terrorism incident involving a radiological dispersion device. The foam formulation is more concentrated and more stable than the current blast suppression foam (AFC-380), which reduces the logistics burden on the user.

  9. Accumulation of chlorinated benzenes in earthworms

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-12-31

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

  10. The abundance measurement of high concentrated uranium

    International Nuclear Information System (INIS)

    A new measurement schema is established than can be conveniently used to measure the abundance of high concentrated uranium. It is based on adding a new SEM counting channel to MAT-261 mass spectrometer. It can be used to measure the abundance of high concentrated uranium, ranging from 99.99% to 99.99999%. The schema can be widely applied to producing, separating and testing of uranium. (authors)

  11. [Benzene pollution in the city of Bari].

    Science.gov (United States)

    Cassano, F; Bavaro, P; De Marinis, G; Bukvic, N; Giacomantonio, A

    1998-01-01

    The Authors reported data of benzene concentrations obtained in Bari during period of time between 1990 and 1995; the measured levels of benzene concentrations are not in accord with referent values prescribed by the law, mostly always they are exceeded. Present study also discuss problems related to gasoline consumption and the number of cars in circulation. PMID:9658241

  12. Multielectron effects in high harmonic generation in N_2 and benzene: simulation using a non-adiabatic quantum molecular dynamics approach for laser-molecule interactions

    CERN Document Server

    Dundas, Daniel

    2012-01-01

    A mixed quantum-classical approach is introduced which allows the dynamically response of molecules driven far from equilibrium to be modeled. This method is applied here to the interaction of molecules with intense, short-duration laser pulses. The electronic response of the molecule is described using time-dependent density functional theory (TDDFT) and the resulting Kohn-Sham equations are solved numerically using finite difference techniques in conjunction with local and global adaptations of an underlying grid in curvilinear coordinates. Using this approach, simulations can be carried out for a wide range of molecules and both all-electron and pseudopotential calculations can be performed. The approach is applied to the study of high harmonic generation in N_2 and benzene using linearly-polarized laser pulses and to the best of our knowledge, the results for benzene represent the first TDDFT calculations of high harmonic generation in benzene using linearly polarized laser pulses. For N_2 an enhancement ...

  13. Photovoltaic concentration at ultra-high flux

    Science.gov (United States)

    Gordon, Jeffrey M.; Katz, Eugene A.; Feuermann, Daniel; Huleihil, Mahmoud

    2004-09-01

    Experimental results generated with novel miniature fiber-optic concentrators and commercial tandem III-V concentrator solar cells are reported, including (1) measured power densities up to 10,000 suns, (2) solar cell efficiencies in excess of 30% and (3) totally passive cooling. Mini-dish concentrators (a) generate uniform and individualized cell illumination, (b) allow assembly from readily available elements, and (c) are devoid of chromatic aberration. Measurements include the sensitivity of conversion efficiency to (i) power input, (ii) extreme flux inhomogeneities and (iii) the modified spectrum from fiber-optic concentrators. The weak sensitivity of cell performance to acute non-uniformities in flux map is addressed with a relatively simple model that regards the cell as an effective parallel connection of its uniformly irradiated areal elements. Our findings bode favorably for the feasibility of such concentrator designs at concentration levels as high as thousands of suns.

  14. Human benzene metabolism following occupational and environmental exposures.

    Science.gov (United States)

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

    2010-03-19

    We previously reported evidence that humans metabolize benzene via two enzymes, including a hitherto unrecognized high-affinity enzyme that was responsible for an estimated 73% of total urinary metabolites [sum of phenol (PH), hydroquinone (HQ), catechol (CA), E,E-muconic acid (MA), and S-phenylmercapturic acid (SPMA)] in nonsmoking females exposed to benzene at sub-saturating (ppb) air concentrations. Here, we used the same Michaelis-Menten-like kinetic models to individually analyze urinary levels of PH, HQ, CA and MA from 263 nonsmoking Chinese women (179 benzene-exposed workers and 84 control workers) with estimated benzene air concentrations ranging from less than 0.001-299 ppm. One model depicted benzene metabolism as a single enzymatic process (1-enzyme model) and the other as two enzymatic processes which competed for access to benzene (2-enzyme model). We evaluated model fits based upon the difference in values of Akaike's Information Criterion (DeltaAIC), and we gauged the weights of evidence favoring the two models based upon the associated Akaike weights and Evidence Ratios. For each metabolite, the 2-enzyme model provided a better fit than the 1-enzyme model with DeltaAIC values decreasing in the order 9.511 for MA, 7.379 for PH, 1.417 for CA, and 0.193 for HQ. The corresponding weights of evidence favoring the 2-enzyme model (Evidence Ratios) were: 116.2:1 for MA, 40.0:1 for PH, 2.0:1 for CA and 1.1:1 for HQ. These results indicate that our earlier findings from models of total metabolites were driven largely by MA, representing the ring-opening pathway, and by PH, representing the ring-hydroxylation pathway. The predicted percentage of benzene metabolized by the putative high-affinity enzyme at an air concentration of 0.001 ppm was 88% based upon urinary MA and was 80% based upon urinary PH. As benzene concentrations increased, the respective percentages of benzene metabolized to MA and PH by the high-affinity enzyme decreased successively to 66 and 77% at 0.1 ppm, 20 and 58% at 1 ppm, and 2.7 and 17% at 10 ppm. This indicates that the putative high-affinity enzyme was active primarily below 1 ppm and favored the ring-opening pathway. PMID:20026321

  15. Stress concentration effects in high pressure components

    International Nuclear Information System (INIS)

    This paper examines the stress concentration effects of sideholes in thick walled, high pressure cylinders. It has been shown that the theoretical stress concentration factor at the intersection of a small crossbore in a closed end, thick walled cylinder varies between 3.0 and 4.0. Tests have shown that this effect can be greatly reduced in practice by carefully radiusing the bore intersection and autofrettaging the cylinder. It has also been shown that the minimum stress concentration factor occurs when the main bore and sidehole or crossbore have the same diameter, and the radius of the intersection is approximately equal to the sidehole radius. When the bore and sidehole intersection angle decreases from 90 degrees, the stress concentration factor increases significantly. Knowledge of these fundamental relationships can be used in maintaining, as well ad designing, high pressure equipment

  16. Construction of sole benzene ring porous aromatic frameworks and their high adsorption properties.

    Science.gov (United States)

    Li, Lina; Cai, Kun; Wang, Pengyuan; Ren, Hao; Zhu, Guangshan

    2015-01-14

    Porous organic frameworks (POFs), with their excellent performance in catalysis, electricity, sensor, gas storage, and separation, have attracted a great deal of attention from researchers all over the world. Generally, the monomers of POF materials require a rigid three-dimensional molecule configuration together with special functional groups, as well as being triggered by noble metal catalysts. Here we report a low-cost and easy-construction strategy for synthesizing PAF materials. A series of flat multi-benzene compounds are selected as building units, and those phenyl rings could couple together to form polymeric skeletons. The BET surface areas of resulting PAFs are moderate, ranging from 777 to 972 m(2) g(-1). However, they unexpectedly exhibit superior gas sorption capacities. At 1.0 bar and 77 K, the H2 uptake of PAF-48 reaches 215 cm(3) g(-1). In addition, PAF-49 shows excellent performance in carbon dioxide and methane sorption, with values of 104 and 35 cm(3) g(-1), respectively. With those adsorption properties, these PAF materials could be considered as potential candidates for energetic gas adsorbents. PMID:25495481

  17. Excretion of 1,2,4-benzenetriol in the urine of workers exposed to benzene.

    OpenAIRE

    Inoue, O.; Seiji, K.; Nakatsuka, H.; Watanabe, T.; Yin, S.; Li, G. L.; Cai, S. X.; Jin, C.; Ikeda, M.

    1989-01-01

    Urine samples were collected from 152 workers (64 men, 88 women) who had been exposed to benzene, 53 workers (men only) exposed to a mixture of benzene and toluene, and 213 non-exposed controls (113 men, 100 women). The samples were analysed for 1,2,4-benzentriol (a minor metabolite of benzene) by high performance liquid chromatography. The time weighted average solvent exposure of each worker was monitored by diffusive sampling technique. The urinary concentration of 1,2,4-benzentriol relate...

  18. High Concentration Suspensions Under Strong Tidal Flows

    Science.gov (United States)

    Kineke, G. C.; Milligan, T. G.; Heath, K. M.; Law, B. A.

    2006-12-01

    An experiment investigating the influence of high-concentration suspensions of fine sediments (fluid muds) on a quasi-steady flow was carried out in the Petitcodiac River, Moncton, New Brunswick, Canada in August 2006. Concurrent measurements of fluid properties (salinity, temperature, density), suspended-sediment concentration, current velocity and shear were made throughout the water column over portions of several tidal cycles. The Petitcodiac was chosen because of consistently high suspended-sediment concentrations (0.5- >200 g/L) and large tidal range (>4 m) producing strong current velocities (> 1.5 m/s). Thus the Peticodiac serves as an ideal natural flume for examining the behavior of muddy suspensions under both accelerating and decelerating flows. Instrumentation included a profiling package with paired electromagnetic current meters mounted 0.6 m apart, a CTD, and an Optical Backscatterance Sensor with a pump system for in situ calibrations. Approximately 1.5 hours after the passage of the tidal bore and a fully mixed turbulent flow, the water column begins to stratify and a high concentration bottom layer forms persisting through the ensuing ebb. Measured suspended-sediment concentrations reached 286 g/L at the bottom and low shear rates of 0.13 s-1 in the upper water column increased to ~0.5 s-1 through the lutocline 1 m above the bed, and decreased to approximately 0 within the fluid mud. Analysis is in progress and the data set provides an excellent means to test threshold conditions regarding suppression of turbulence by sediment-induced stratification and the carrying capacity of turbulent flows.

  19. Cellulase Inhibition by High Concentrations of Monosaccharides

    DEFF Research Database (Denmark)

    Hsieh, Chia-Wen; Cannella, David

    2014-01-01

    Biological degradation of biomass on an industrial scale culminates in high concentrations of end products. It is known that the accumulation of glucose and cellobiose, end products of hydrolysis, inhibit cellulases and decrease glucose yields. Aside from these end products, however, other monosaccharides such as mannose and galactose (stereoisomers of glucose) decrease glucose yields as well. NMR relaxometry measurements showed direct correlations between the initial T2 of the liquid phase in which hydrolysis takes place and the total glucose production during cellulose hydrolysis, indicating that low free water availability contributes to cellulase inhibition. Of the hydrolytic enzymes involved, those acting on the cellulose substrate, that is, exo- and endoglucanases, were the most inhibited. The ?-glucosidases were shown to be less sensitive to high monosaccharide concentrations except glucose. Protein adsorption studies showed that this inhibition effect was most likely due to catalytic, and not binding,inhibition of the cellulases.

  20. Mechanistic considerations in benzene physiological model development

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-12-01

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

  1. Pipe flow of highly concentrated sludge.

    Science.gov (United States)

    Slatter, Paul

    2008-11-01

    Industries that pump sludges experience pressure to operate at higher concentrations with sludges that have high mechanical strength properties. The viscous character of the sludge becomes increasingly non-Newtonian and yield stress in nature. The two principal problems are regime determination and laminar flow settling, which ultimately results in pipe blockage. In facing the diversities that sludge management currently presents, it is important to resolve these issues and develop solutions for engineering practice. The approaches developed at the Flow Process Research Centre to deal with these problems are introduced. The objectives of this paper are to introduce experimental data of the phenomena associated with the pipe flow of highly concentrated sludge, and use these to develop and evaluate predictive modeling approaches suitable for engineering design purposes. For the prediction of transitional flow, a new general approach for visco-plastic fluids in industrially relevant pipe sizes is presented, based on dimensional analysis of the flow problem. Settled bed behavior is modeled using an adapted two-layer model approach, in all flow regimes. The modeling approaches are evaluated using the experimental results obtained. The analysis shows that the present work provides a workable solution for the prediction of the pipe flow of highly concentrated sludges, for engineering design purposes. PMID:18821237

  2. High efficiency silicon concentrator solar cells

    Science.gov (United States)

    Zhao, Jianhua

    1990-06-01

    Techniques were investigated for improving the energy conversion efficiency of silicon concentrator solar cells. This aim was achieved with the demonstration of bifacially contacted silicon concentrator solar cells of markedly superior performance. An additional achievement was the demonstration of substantial improvements in the performance of non-concentrating, one-sun cells. The improvements in the one-sun cell area were achieved by optimization of the Passivated Emitter Solar Cell (PESC) technology. Aluminum gettering and emitter surface oxide-passivation played key roles for the PESC cells. The optimized PESC one-sun cell demonstrated an independently confirmed efficiency of 21.4 percent. The optimized PESC technology was also successfully applied to the fabrication of silicon concentrator cells on low resistivity substrates. The effects of metal contact resistance and heavy phosphorus diffusion were areas requiring additional careful investigation in this case. A concentrator cell after optimization demonstrated 23.4 percent efficiency at 100 suns, again independently confirmed. Although very high by normal standards, the efficiency was limited by the trade-off of the resistance and the shading of the front metal fingers. The need for the trade-off was eliminated by the application of prismatic covers, which steer the incident light onto the cell active areas avoiding metal fingers. The Passivated Emitter and Rear Cells (PERC) incorporating TCA (trichloro-ethane) processing improved the one-sun cell efficiency further to 21.8 percent. The improvement came from low recombination at surfaces and in the bulk resulting from the TCA processing and from reduced rear contact area. Antireflection coatings and prismatic cover design were also theoretically optimized. When combined with light trapping techniques, 27 percent efficiency silicon concentrator cell will be obtained with this approach in the near future.

  3. (Liquid + liquid) equilibria for benzene + cyclohexane + N,N-dimethylformamide + sodium thiocyanate

    International Nuclear Information System (INIS)

    Graphical abstract: On the left, the figure was phase diagram about the LLE date. On the right, the figure was about the effects of mass fraction of benzene in the raffinate phase to the selectivity(S) coefficient under different salt concentration. ?, the NaSCN and DMF in ratio of 5/95; • , the NaSCN and DMF in ratio of 10/90; ?, the NaSCN and DMF in ratio of 15/85; ?, the NaSCN and DMF in ratio of 20/80; ?, the NaSCN and DMF in ratio of 23/77. ?, only DMF was used extractant (the selectivity coefficient was calculated by literature 17). w22, refer to the mass fraction of benzene in the raffinate phase (cyclohexane-rich phase). Highlights: • (Liquid + liquid) equilibrium for quaternary system was measured. • The components include benzene, cyclohexane, N,N-dimethylformamide, sodium thiocyanate. • The (liquid + liquid) equilibrium data can be well correlated by the NRTL model. • Separation of benzene and cyclohexane by NaSCN + DMF was discussed. -- Abstract: (Liquid + liquid) equilibrium (LLE) data for benzene + cyclohexane + N,N-dimethylformamide (DMF) + sodium thiocyanate (NaSCN) were measured experimentally at atmospheric pressure and 303.15 K. The selectivity coefficients from these LLE data were calculated and compared to those previously reported in the literature for the systems (benzene + cyclohexane + DMF) and (benzene + cyclohexane + DMF + KSCN). The NRTL equation was used to correlate the experimental data. The agreement between the predicted and experimental results was good. It was found that the selectivity coefficients of DMF + NaSCN for benzene ranged from 2.45 to 11.99. Considering the relatively high extraction capacity and selectivity for benzene, DMF + NaSCN may be used as a potential extracting solvent for the separation of benzene from cyclohexane

  4. ?-galactosidase stability at high substrate concentrations

    OpenAIRE

    Warmerdam, A.; Boom, R. M.; Janssen, A. E. M.

    2013-01-01

    Enzymatic synthesis of galacto-oligosaccharides is usually performed at high initial substrate concentrations since higher yields are obtained. We report here on the stability of ?-galactosidase from Bacillus circulans at 25, 40, and 60°C in buffer, and in systems with initially 5.0 and 30% (w/w) lactose. In buffer, the half-life time was 220 h and 13 h at 25 and 40°C, respectively, whereas the enzyme was completely inactivated after two hours at 60°C. In systems with 5.0 and 30% (w/w) ...

  5. Multispecies hydrodynamic dispersion under high concentration gradients

    Science.gov (United States)

    Sarioglu, Murat Savas; Kucuker, Mehmet Ali; Copty, Nadim K.

    2013-01-01

    Recent research suggests that when high concentration gradients (HCG) are present, resulting sharp density differences can cause the dispersive flux relationship to deviate from its classical Fickian form. This paper presents stable, upward, miscible displacement experiments conducted in two different types of porous media for a wide range of concentration differences between resident and displacing fluids. The considered groundwater velocities ranged from advection-dominated transport to velocities where the contribution of molecular diffusion is important, with the corresponding Peclet numbers ranging from 0.2 to 320. In addition to single component displacing fluids, mixtures consisting of multiple solutes were considered. The results of this study provide further evidence that classical Fick's law over-estimates the dispersion coefficient under HCG conditions. The decrease in the apparent dispersion coefficient is shown to be a nonlinear function of both concentration difference and groundwater velocity. This observation is attributed to gravitational effects at the sub-continuum scale which are not directly accounted for in classical variable density advection/dispersion models. Mixture experiments showed that the dispersive behaviors of individual components in a groundwater contaminant mixture are coupled.

  6. Diverse microbial species survive high ammonia concentrations

    Science.gov (United States)

    Kelly, Laura C.; Cockell, Charles S.; Summers, Stephen

    2012-04-01

    Planetary protection regulations are in place to control the contamination of planets and moons with terrestrial micro-organisms in order to avoid jeopardizing future scientific investigations relating to the search for life. One environmental chemical factor of relevance in extraterrestrial environments, specifically in the moons of the outer solar system, is ammonia (NH3). Ammonia is known to be highly toxic to micro-organisms and may disrupt proton motive force, interfere with cellular redox reactions or cause an increase of cell pH. To test the survival potential of terrestrial micro-organisms exposed to such cold, ammonia-rich environments, and to judge whether current planetary protection regulations are sufficient, soil samples were exposed to concentrations of NH3 from 5 to 35% (v/v) at -80°C and room temperature for periods up to 11 months. Following exposure to 35% NH3, diverse spore-forming taxa survived, including representatives of the Firmicutes (Bacillus, Sporosarcina, Viridibacillus, Paenibacillus, Staphylococcus and Brevibacillus) and Actinobacteria (Streptomyces). Non-spore forming organisms also survived, including Proteobacteria (Pseudomonas) and Actinobacteria (Arthrobacter) that are known to have environmentally resistant resting states. Clostridium spp. were isolated from the exposed soil under anaerobic culture. High NH3 was shown to cause a reduction in viability of spores over time, but spore morphology was not visibly altered. In addition to its implications for planetary protection, these data show that a large number of bacteria, potentially including spore-forming pathogens, but also environmentally resistant non-spore-formers, can survive high ammonia concentrations.

  7. Validation of Armadillo officinalis Dumèril, 1816 (Crustacea, Isopoda, Oniscidea) as a bioindicator: in vivo study of air benzene exposure.

    Science.gov (United States)

    Agodi, A; Oliveri Conti, G; Barchitta, M; Quattrocchi, A; Lombardo, B M; Montesanto, G; Messina, G; Fiore, M; Ferrante, M

    2015-04-01

    This study tests the potential for using Armadillo officinalis as a bioindicator of exposure to and activation of benzene metabolic pathways using an in vivo model. A. officinalis specimens collected in a natural reserve were divided into a control and three test groups exposed to 2.00, 5.32 or 9.09 µg/m(3) benzene for 24h. Three independent tests were performed to assess model reproducibility. Animals were dissected to obtain three pooled tissue samples per group: hepatopancreas (HEP), other organs and tissues (OOT), and exoskeleton (EXO). Muconic acid (MA), S-phenylmercapturic acid (S-PMA), two human metabolites of benzene, and changes in mtDNA copy number, a human biomarker of benzene exposure, were determined in each sample; benzene was determined only in EXO. MA was measured by high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection, S-PMA by triple quadrupole mass spectrometer liquid chromatography with electro spray ionization (LC-MS-ESI-TQD), mtDNA by real-time quantitative PCR and end-point PCR, and benzene by quadrupole mass spectrometer head-space gas chromatography (HSGC-MS). MA and S-PMA levels rose both in HEP and OOT; EXO exhibited increasing benzene concentrations; and mtDNA copy number rose in HEP but not in OOT samples. Overall, our findings demonstrate that A. officinalis is a sensitive bioindicator of air benzene exposure and show for the first time its ability to reproduce human metabolic dynamics. PMID:25638523

  8. Dissociation of molecular aggregates under high hydrostatic pressure: the influence of water structure on Benzene cluster solubility

    Scientific Electronic Library Online (English)

    Arlan S., Gonçalves; Ernesto R., Caffarena; Pedro G., Pascutti.

    1227-12-01

    Full Text Available Em condições críticas, a água pode solvatar moléculas hidrofóbicas, tornando-se um solvente poderoso para agentes apolares. Para discutir o efeito da pressão em agregados de benzeno em água, foram executadas seis simulações consecutivas de 5000 ps (picossegundos) por modelagem e dinâmica molecular d [...] e moléculas de benzeno inseridas em caixas d´água cúbicas em diferentes condições de pressão, de 1 bar a 5 kbar. O raio de giro, o coeficiente de difusão, a função de distribuição radial, o número de ligações hidrogênio entre as moléculas de água e a área acessível ao solvente, foram monitorados. Os resultados mostraram que acima de 3 kbar, a estrutura da segunda camada de solvatação desaparece e os agregados de benzeno desmembram-se gradualmente. Até 2 kbar, a solubilidade e a difusão das moléculas de benzeno são inversamente proporcionais ao aumento da pressão e acima de 3 kbar o comportamento é o inverso. Abstract in english In some critical conditions water can solvate hydrophobic molecules, becoming a powerful solvent for nonpolar agents. To discuss the pressure effect on hydrated benzene clusters we carried out six consecutive 5000 ps (pico seconds) molecular dynamics simulations of benzene molecules in water cubic b [...] oxes at different pressure conditions, ranging from 1 bar to 5 kbar. Radius of gyration, diffusion coefficient, radial atomic pair distribution functions, number of hydrogen bonds between water molecules and the solvent accessible surface were monitored. Results showed that above 3 kbar the second hydration layer structure vanishes and the benzene clusters start to break up gradually. Up to 2 kbar, the solubility and diffusion of benzene molecules are inversely proportional to the increase of the pressure and above 3 kbar this behavior is inverted.

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

    OpenAIRE

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

    1994-01-01

    Benzene, an important industrial solvent, is also present in unleaded gasoline and cigarette smoke. The hematotoxic effects of benzene are well documented and include aplastic anemia and pancytopenia. Some individuals exposed repeatedly to cytotoxic concentrations of benzene develop acute myeloblastic anemia. It has been hypothesized that metabolism of benzene is required for its toxicity, although administration of no single benzene metabolite duplicates the toxicity of benzene. Several inve...

  10. High pressure liquid chromatographic method for the separation and quantitation of water-soluble radiolabeled benzene metabolites

    International Nuclear Information System (INIS)

    The glucuronide and sulfate conjugates of benzene metabolite as well as muconic acid and pre-phenyl- and phenylmercapturic acids were separated by ion-pairing HPLC. The HPLC method developed was suitable for automated analysis of a large number of tissue or excreta samples. p-Nitrophenyl [14C]glucuronide was used as an internal standard for quantitation of these water-soluble metabolites. Quantitation was verified by spiking liver tissue with various amounts of phenylsulfate or glucuronides of phenol, catechol, or hydroquinone and analyzing by HPLC. Values determined by HPLC analysis were within 10% of the actual amount with which the liver was spiked. The amount of metabolite present in urine following exposure to [3H]benzene was determined using p-nitrophenyl [14C]glucuronide as an internal standard. Phenylsulfate was the major water-soluble metabolite in the urine of F344 rats exposed to 50 ppm [3H]benzene for 6 h. Muconic acid and an unknown metabolite which decomposed in acidic media to phenylmercapturic acid were also present. Liver, however, contained a different metabolic profile. This indicates that urinary metabolite profiles may not be a true reflection of what is seen in individual tissues

  11. Aromaticity of benzene in condensed phases. A case of a benzene-water system

    Science.gov (United States)

    Zborowski, Krzysztof K.

    2014-05-01

    A theoretical Density Functional Theory study was performed for a benzene molecule in water cages. Two DFT functionals (B3LYP and BLYP) were employed. The optimized geometries of the studied clusters were used to calculate the aromaticity of benzene in a condensed phase using the aromaticity indices: HOMA, NICS, PDI, and H. The results were compared with aromaticity of a single benzene molecule in the gas phase and in the solvent environment provided by the PCM continuum model. It is argued that high aromaticity of benzene in the gas phase is retained in the water environment.

  12. H-D exchange between benzene and the OH groups of alumina

    International Nuclear Information System (INIS)

    H-D exchange of benzene with the OH groups of aluminas was investigated using FTIR spectroscopy. The reactions benzene-d6-alumina and benzene-alumina-d are of first order with respect to OH and benzene concentrations (E/sub A/ = 112 kJ/mol). They mainly take place on centers - probably Lewis acid-base pairs - which are poisoned by CO2 adsorbed as carbonate. 8 figures, 3 tables

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

    OpenAIRE

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

    1988-01-01

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

  14. Reactions of solvated electrons with solutes at high concentrations. A laser photolysis and pulse radiolysis study

    International Nuclear Information System (INIS)

    Solvated electrons were produced in several liquids by laser photoionization of aromatic solutes, and by pulse radiolysis. The yields of solvated electrons were decreased by high concentrations (0.1 - 1.0M) of phenol, benzene, and ethyl acetate; the effectiveness of the solutes in reducing the e-/sub s/ yields was greater in the photolysis experiments than in the corresponding pulse radiolysis experiments. The data were, however, identical with light of wavelength 3471 or 2650 A, from ruby and neodymium lasers, respectively. The data are used to discuss several theories. Solvated electrons in alcohols were photobleached with red light (lambda = 6942 A) giving H atoms. The quantum yield for the process was found to be low

  15. Reactions of solvated electrons with solutes at high concentrations. A laser photolysis and pulse radiolysis study

    International Nuclear Information System (INIS)

    Solvated electrons were produced in several liquids by laser photoionization of aromatic solutes, and by pulse radiolysis. The yields of solvated electrons were decreased by high concentrations (0.1--1.0M) of phenol, benzene, and ethyl acetate; the effectiveness of the solutes in reducing the e-/subs/ yields was greater in the photolysis experiments than in the corresponding pulse radiolysis experiments. The data were, however, identical with light of wavelength 3471 or 2650 A, from ruby and neodymium lasers, respectively. The data are used to discuss several theories. Solvated electrons in alcohols were photobleached with red light (lambda=6942 A) giving H atoms. The quantum yield for the process was found to be low

  16. The toxicology of benzene.

    OpenAIRE

    Snyder, R.; Witz, G.; Goldstein, B. D.

    1993-01-01

    Benzene is metabolized, primarily in the liver, to a series of phenolic and ring-opened products and their conjugates. The mechanism of benzene-induced aplastic anemia appears to involve the concerted action of several metabolites acting together on early stem and progenitor cells, as well as on early blast cells, such as pronormoblasts and normoblasts to inhibit maturation and amplification. Benzene metabolites also inhibit the function of microenvironmental stromal cells necessary to suppor...

  17. Production of high concentrations of yeast

    Energy Technology Data Exchange (ETDEWEB)

    1981-11-10

    A microbe is aerobically cultured using O/sub 2/ or a gas rich in O/sub 2/. The grown cells are washed, concentrated and a portion of the cells used as a seed culture. Thus, Saccharomyces cerevisiae (bakers' yeast) was cultured in a jar fermentor by flow down system maintaining the dissolved O/sub 2/ at 2-5 mg/L; volume of the initial medium containing 30% glucose was 350 mL and the initial washed cell concentration was 50 g dry cells/L. After 12 hours of cultivation, the volume of the medium increased to 750 mL and the cell concentration rose to 102 g dry cells/L; the yield was 49% with respect to glucose. The cells were washed and the cultivation was repeated by use of the washed cells; cell concentration reached 105 g dry cells/L.

  18. 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)

    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)

  19. Studies on biological effects induced by chronic ?-irradiation combined with benzene injection in rabbits

    International Nuclear Information System (INIS)

    30 healthy male rabbits, 6-7 months of age, were equally divided into 6 groups. Animals of control and radiation, low benzene and low benzene radiation, high benzene and high benzene radiation groups were injected with 0.6 ml peanut oil, 0.6 ml peanut oil 0.06 ml benzene or 0.6 ml peanut oil + 0.6 ml benzene/d/rabbit, respectively, 5 days per week for 14 weeks. After injection, animals of radiation, low benzene radiation, high benzene radiation groups were irradiated at 0.899 mGy/min. x 60/d. The main results were summarized as follows: (1) The changes of hematopoietic function are close related to the injected dosage of benzene. Damages of hematoietic function in rabbits are enhanced by combined effect of benzene and ?-rays. (2) ?-rays and benzene can induce chromosome aberrations and SCEs. Chromosome aberrations in blood lymphocytes are higher than in marrow cells. Chromosome aberrations induced by ?-rays are higher than SCEs, but no significant linear correlation between the dosage and effects was found. The SCEs of blood lymphocytes induced by benzene are more obvious than chromosome aberrations, Moreover, linear dose effect correlation of acentric in high benzene groups and SCE in high benzene and low benzene radiation groups were observed. The chromosome aberration yield induced by ?-rays can significantly be enhanced by treatment with benzene. The combined cytogenetic effects of radiation with benzene could be synergetic mainly in dicentrics plus rings, beic mainly in dicentrics plus rings, being mainly additive in acentric. SCEs induced by benzene combined with ?-radiation could be enhanced in the low benzene radiation groups. (3) Benzene is a weak mutagen for male reproductive cells, because it can induce more abnormal sperms. Histological damages of tests in rabbits were also enhanced by combined effects of ?-radiation and benzene

  20. 3H-benzene metabolism in rabbit bone marrow

    International Nuclear Information System (INIS)

    An assay for benzene metabolism using 3H-benzene and high pressure liquid chromatography was developed. 3H-benzene metabolism (2 pmoles benzene equivalents/mg protein/min) required the presence of a TPNH generating system and was inhibited 80% in the presence of a CO:O2 (9:1) atmosphere. The products of 3H-benzene rabbit bone marrow microsomal metabolism were phenol and an unidentified metabolite. Cytochrome P-450 (26 to 51 pmoles/mg microsomal protein) and cytochrome c reductase activity (7.8 to 21.0 nmole/mg microsomal protein/min) were detected in rabbit bone marrow

  1. Fingering phenomena at high surfactant concentrations

    Science.gov (United States)

    Matar, Omar K.

    2005-11-01

    The spreading of a soluble surfactant droplet on a pre-existing thin liquid layer is considered at concentrations beyond the critical micelle concentration (CMC). Lubrication theory is used to derive a coupled system of four two-dimensional nonlinear evolution equations for the film thickness, monomer interface and bulk concentrations and micellar concentration. These equations are closed by a nonlinear surfactant equation of state. Our numerical results for the base state indicate that increasing the mass of surfactant deposited leads to the development of a protuberance that appears at the edge of the drop. For a sufficiently large mass, this feature separates from the drop to form a distinct secondary front that lies behind a leading front, which usually accompanies the spreading process. The results of our transient growth analysis and transient numerical simulations indicate that these features are vulnerable to transverse perturbations leading to the formation of fingers. The results obtained in the present work appear to capture phenomena recently observed experimentally.

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

    DEFF Research Database (Denmark)

    Emmerling, Uwe; Rasmussen, Peter

    1998-01-01

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

  3. Bioremediation of benzene-, MTBE- and ammonia-contaminated groundwater with pilot-scale constructed wetlands

    International Nuclear Information System (INIS)

    In this pilot-scale constructed wetland (CW) study for treating groundwater contaminated with benzene, MTBE, and ammonia-N, the performance of two types of CWs (a wetland with gravel matrix and a plant root mat) was investigated. Hypothesized stimulative effects of filter material additives (charcoal, iron(III)) on pollutant removal were also tested. Increased contaminant loss was found during summer; the best treatment performance was achieved by the plant root mat. Concentration decrease in the planted gravel filter/plant root mat, respectively, amounted to 81/99% for benzene, 17/82% for MTBE, and 54/41% for ammonia-N at calculated inflow loads of 525/603 mg/m2/d, 97/112 mg/m2/d, and 1167/1342 mg/m2/d for benzene, MTBE, and ammonia-N. Filter additives did not improve contaminant depletion, although sorption processes were observed and elevated iron(II) formation indicated iron reduction. Bacterial and stable isotope analysis provided evidence for microbial benzene degradation in the CW, emphasizing the promising potential of this treatment technique. - Highlights: ? BTEX compounds contaminated groundwater can be efficiently treated by CWs. ? The removal efficiency depended on CW type, season and contaminant. ? The plant root mat revealed better treatment results than the gravel filter CW. ? Best results achieved by the plant root mat (99% benzene concentration decrease). ? Stable isotope analysis and MPN indicated high benzysis and MPN indicated high benzene remediation potential. - Gravel bed constructed wetlands and a plant root mat system efficiently eliminated fuel hydrocarbons (benzene, MTBE) and ammonia-N from groundwater at a pilot-scale.

  4. Monitoring in situ benzene biodegradation in contaminated aquifers using compound-specific stable isotope analysis (CSIA)

    International Nuclear Information System (INIS)

    Full text: Benzene is a groundwater pollutant of specific concern, since it causes a significant health risk due to its widespread occurrence, relatively high water solubility and toxicity. Biodegradation is the only in situ process leading to a decrease of benzene concentrations in groundwater coupled to a sustainable mass removal of the contaminant. Therefore, the evaluation of in situ biodegradation of benzene is essential for the implementation of groundwater management strategies such as Natural Attenuation (NA). In recent years, Compound-specific Stable Isotope Analysis (CSIA) has gained more and more attention as a tool for characterizing and assessing in situ biodegradation of organic pollutants in contaminated aquifers. This concept relies on the stable isotope fractionation occurring during the microbial degradation leading to an enrichment of heavier stable isotopes in the residual fraction of a contaminant. Thus, the observation of isotope ratio shifts for carbon, hydrogen or other elements that are involved in cleavage or generation of chemical bonds during the initial step of microbial transformation can be used as an indicator for in situ biodegradation. In the present study, CSIA was applied to investigate biodegradation of benzene within an aquifer located in the area of a former hydrogenation plant close to the city of Zeitz (Saxony-Anhalt, Germany). Based on multi-level sampling, we determined the vertical and horizontal distribution of carbon and hnd horizontal distribution of carbon and hydrogen isotope ratios of benzene within the contaminant plume. Furthermore, the carbon and hydrogen isotope fractionation associated to microbial benzene degradation was investigated in laboratory experiments with anaerobic enrichment cultures from the field site and aerobic pure cultures. In agreement with recently published studies, our results showed that aerobic and anaerobic benzene degradation lead to nearly the same carbon isotope fractionation but to significantly different hydrogen isotope fractionation. Hence, it is possible to distinguish between aerobic and anaerobic benzene biodegradation in the field by means of carbon and hydrogen isotope ratio analyzes. Our field data provided evidence for anaerobic degradation of benzene especially at the fringe of the contaminant plume. Changes in carbon isotope ratios were used to quantify the in situ biodegradation of benzene using the Rayleigh equation. Furthermore, the applicability of the Rayleigh equation for the assessment of in situ biodegradation was investigated and showed limitations and advantages of this concept. In conclusion, our investigations show that CSIA is a useful tool for monitoring in situ biodegradation of benzene in contaminated aquifers. (author)

  5. Highly selective GaN-nanowire/TiO{sub 2}-nanocluster hybrid sensors for detection of benzene and related environment pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Aluri, Geetha S; Motayed, Abhishek; Davydov, Albert V; Oleshko, Vladimir P [Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Bertness, Kris A; Sanford, Norman A [Physical Measurement Laboratory, National Institute of Standards and Technology, Boulder, CO 80305 (United States); Rao, Mulpuri V, E-mail: amotayed@nist.gov [Department of Electrical and Computer Engineering, George Mason University, Fairfax, VA 22030 (United States)

    2011-07-22

    Nanowire-nanocluster hybrid chemical sensors were realized by functionalizing gallium nitride (GaN) nanowires (NWs) with titanium dioxide (TiO{sub 2}) nanoclusters for selectively sensing benzene and other related aromatic compounds. Hybrid sensor devices were developed by fabricating two-terminal devices using individual GaN NWs followed by the deposition of TiO{sub 2} nanoclusters using RF magnetron sputtering. The sensor fabrication process employed standard microfabrication techniques. X-ray diffraction and high-resolution analytical transmission electron microscopy using energy-dispersive x-ray and electron energy-loss spectroscopies confirmed the presence of the anatase phase in TiO{sub 2} clusters after post-deposition anneal at 700 deg. C. A change of current was observed for these hybrid sensors when exposed to the vapors of aromatic compounds (benzene, toluene, ethylbenzene, xylene and chlorobenzene mixed with air) under UV excitation, while they had no response to non-aromatic organic compounds such as methanol, ethanol, isopropanol, chloroform, acetone and 1,3-hexadiene. The sensitivity range for the noted aromatic compounds except chlorobenzene were from 1% down to 50 parts per billion (ppb) at room temperature. By combining the enhanced catalytic properties of the TiO{sub 2} nanoclusters with the sensitive transduction capability of the nanowires, an ultra-sensitive and selective chemical sensing architecture is demonstrated. We have proposed a mechanism that could qualitatively explain the observed sensing behavior.

  6. Hydrogen bonding and charge transfer interactions in exciplexes formed by excited indole and monosubstituted benzenes in cyclohexane

    Science.gov (United States)

    Rivarola, Claudia; Bertolotti, Sonia G.; Borsarelli, Claudio D.; Cosa, Juan J.; Previtali, Carlos M.; Neumann, Miguel G.

    1996-11-01

    The interaction between the excited singlet state of indole derivatives with simple monosubstituted benzenes has been investigated in cyclohexane by steady state and time resolved fluorescence spectroscopy. The fluorescence quenching efficiency of indole increases in the order benzene, toluene, chlorobenzene and benzonitrile. For indole derivatives substituted on the N atom of the heterocyclic ring the quenching efficiency is much lower. At high concentrations of the benzenes derivatives the emission spectrum is broader and red shifted and the decay of the emission becomes biexponential. The results are analysed in terms of an exciplex forming mechanism. The binding forces in the exciplex are predominantly of hydrogen bonding for the case of benzene and toluene, while a charge transfer interaction is more likely in the case of chlorobenzene and benzonitrile.

  7. Bioremediation of benzene-, MTBE- and ammonia-contaminated groundwater with pilot-scale constructed wetlands

    Energy Technology Data Exchange (ETDEWEB)

    Seeger, Eva M., E-mail: eva.seeger@ufz.de [Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research - UFZ, Permoserstr. 15, 04318 Leipzig (Germany); Kuschk, Peter; Fazekas, Helga [Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research - UFZ, Permoserstr. 15, 04318 Leipzig (Germany); Grathwohl, Peter [Center of Applied Geoscience, University of Tuebingen, Hoelderlinstr. 12, 72074 Tuebingen (Germany); Kaestner, Matthias [Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research - UFZ, Permoserstr. 15, 04318 Leipzig (Germany)

    2011-12-15

    In this pilot-scale constructed wetland (CW) study for treating groundwater contaminated with benzene, MTBE, and ammonia-N, the performance of two types of CWs (a wetland with gravel matrix and a plant root mat) was investigated. Hypothesized stimulative effects of filter material additives (charcoal, iron(III)) on pollutant removal were also tested. Increased contaminant loss was found during summer; the best treatment performance was achieved by the plant root mat. Concentration decrease in the planted gravel filter/plant root mat, respectively, amounted to 81/99% for benzene, 17/82% for MTBE, and 54/41% for ammonia-N at calculated inflow loads of 525/603 mg/m{sup 2}/d, 97/112 mg/m{sup 2}/d, and 1167/1342 mg/m{sup 2}/d for benzene, MTBE, and ammonia-N. Filter additives did not improve contaminant depletion, although sorption processes were observed and elevated iron(II) formation indicated iron reduction. Bacterial and stable isotope analysis provided evidence for microbial benzene degradation in the CW, emphasizing the promising potential of this treatment technique. - Highlights: > BTEX compounds contaminated groundwater can be efficiently treated by CWs. > The removal efficiency depended on CW type, season and contaminant. > The plant root mat revealed better treatment results than the gravel filter CW. > Best results achieved by the plant root mat (99% benzene concentration decrease). > Stable isotope analysis and MPN indicated high benzene remediation potential. - Gravel bed constructed wetlands and a plant root mat system efficiently eliminated fuel hydrocarbons (benzene, MTBE) and ammonia-N from groundwater at a pilot-scale.

  8. Benzene release. Status report

    International Nuclear Information System (INIS)

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

  9. Drying up the benzene

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, Lynda

    2011-03-15

    In 2007, a directive from the Alberta Energy Resources Conservation Board asked companies running glycol dehydrators to report their benzene emissions. In order to help companies to do so, Process Ecology Inc. developed an online system that calculates, reports and manages dehydrators benzene emissions. This Benzene Emissions Advisor collects data, runs simulation models and stores the results in a database accessible to clients through its website. This software, used by 25 per cent of the market, can now be used for energy optimization purposes. It can inform operators of many saving opportunities, for example turning down the glycol pump.

  10. Benzene release. status report

    Energy Technology Data Exchange (ETDEWEB)

    Dworjanyn, L.O. [Westinghouse Savannah River Company, AIKEN, SC (United States); Rappe, K.G.; Gauglitz, P.A. [Pacific Northwest National Lab., Richland, WA (United States)

    1997-11-04

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

  11. Benzene monitoring at CPPI service stations

    International Nuclear Information System (INIS)

    A study was conducted in which ambient airborne concentration levels of benzene were measured at a representative set of gasoline service stations in Toronto and Vancouver. Benzene is considered to be toxic under the Canadian Environmental Protection Act (CEPA). It is a component in gasoline (0.1 to 4.7 per cent by volume) and is present in vehicle evaporative and exhaust emissions. Measurements were made every 18 days at each station for one year. The objective of the study was to assess the ambient and employee exposure levels of benzene at service stations and to determine whether the levels were typical of those published in the literature. In a 1986 PACE (Petroleum Association for Conservation of the Canadian Environment) survey of exposure to gasoline hydrocarbon vapours at Canadian service stations, airborne benzene concentration data was inconsistent with similar ambient and personal exposure data in the international literature. It was concluded that both the mean ambient benzene concentration and the personal exposure level measurements in this study were generally lower than similar measurements made in other countries. The same observation was made with respect to ambient and personal exposure levels measured in this study vis-a-vis those measured during the PACE study conducted in 1985/86. . 31 refs., 24 tabs., 5 figs

  12. Leukemia and Benzene

    OpenAIRE

    Robert Snyder

    2012-01-01

    Excessive exposure to benzene has been known for more than a century to damage the bone marrow resulting in decreases in the numbers of circulating blood cells, and ultimately, aplastic anemia. Of more recent vintage has been the appreciation that an alternative outcome of benzene exposure has been the development of one or more types of leukemia. While many investigators agree that the array of toxic metabolites, generated in the liver or in the bone marrow, can lead to traumatic bone marrow...

  13. Benzene Monitor System report

    International Nuclear Information System (INIS)

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

  14. An overview of benzene metabolism.

    OpenAIRE

    Snyder, R.; Hedli, C. C.

    1996-01-01

    Benzene toxicity involves both bone marrow depression and leukemogenesis caused by damage to multiple classes of hematopoietic cells and a variety of hematopoietic cell functions. Study of the relationship between the metabolism and toxicity of benzene indicates that several metabolites of benzene play significant roles in generating benzene toxicity. Benzene is metabolized, primarily in the liver, to a variety of hydroxylated and ring-opened products that are transported to the bone marrow w...

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

    International Nuclear Information System (INIS)

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

  16. Muconaldehyde formation from 14C-benzene in a hydroxyl radical generating system

    International Nuclear Information System (INIS)

    It has recently been proposed that muconaldehyde, a six carbon, alpha, beta-unsaturated dialdehyde, may be a hematotoxic metabolite of benzene. The present studies indicate that trans, trans-muconaldehyde is formed from benzene in vitro in a hydroxyl radical (.OH) generating system containing ascorbate, ferrous sulfate and EDTA in phosphate buffer, pH 6.7. Muconaldehyde formed from benzene in the .OH generating system was identified by trapping it with thiobarbituric acid (TBA), which results in the formation of an adduct with a 495 nm absorption maximum and a 510 nm fluorescence emission maximum. These maxima were identical to those observed after reacting authentic trans, trans-muconaldehyde with TBA. This finding was supported by thin layer chromatography and solid phase extraction studies. In those studies benzene-derived muconaldehyde cochromatographed with the muconaldehyde/TBA standard. Analyses of the products from the .OH generating system using high performance liquid chromatography (HPLC) confirm that trans, trans-muconaldehyde is a product of benzene ring fission. Regardless of whether or not TBA was used for trapping, samples from the .OH system incubated with benzene contained a peak which cochromatographed with the muconaldehyde standard. The radioactivity profile of fractions collected during HPLC analysis demonstrates 14C-benzene to be the source of the trans, trans-muconaldehyde. The role of hydroxyl radicals in the formation of muconaldehyde was investigated by using dimethyl sulfoxide, mannitol, and ethanol as .OH scavengers. These scavengers, at concentrations of 10 and 100 mM, were found to cause a dose-dependent decrease in the formation of muconaldehyde

  17. Benzene exposure and the effect of traffic pollution in Copenhagen, Denmark

    Science.gov (United States)

    Skov, Henrik; Hansen, Asger B.; Lorenzen, Gitte; Andersen, Helle Vibeke; Løfstrøm, Per; Christensen, Carsten S.

    Benzene is a carcinogenic compound, which is emitted from petrol-fuelled cars and thus is found ubiquitous in all cities. As part of the project Monitoring of Atmospheric Concentrations of Benzene in European Towns and Homes (MACBETH) six campaigns were carried out in the Municipality of Copenhagen, Denmark. The campaigns were distributed over 1 year. In each campaign, the personal exposure to benzene of 50 volunteers (non-smokers living in non-smoking families) living and working in Copenhagen was measured. Simultaneously, benzene was measured in their homes and in an urban network distributed over the municipality. The Radiello diffusive sampler was applied to sample 5 days averages of benzene and other hydrocarbons. Comparison of the results with those from a BTX-monitor showed excellent agreement. The exposure and the concentrations in homes and in the urban area were found to be close to log-normal distribution. The annual averages of the geometrical mean values were 5.22, 4.30 and 2.90 ?g m -3 for personal exposure, home concentrations and urban concentrations, respectively. Two main parameters are controlling the general level of benzene in Copenhagen: firstly, the emission from traffic and secondly, dispersion due to wind speed. The general level of exposure to benzene and home concentrations of benzene were strongly correlated with the outdoor level of benzene, which indicated that traffic is an important source for indoor concentrations of benzene and for the exposure to benzene.

  18. Quinones as toxic metabolites of benzene

    Energy Technology Data Exchange (ETDEWEB)

    Irons, R.D.

    1985-01-01

    Occupational exposure to benzene has long been associated with toxicity to the blood and bone marrow, including lymphocytopenia, pancytopenia, aplastic anemia, acute myelogenous leukemia, and possible lymphoma. A variety of studies have established that benzene itself is not the toxic species but requires metabolism to reactive intermediates. The bioactivation of benzene is complex. Both primary and secondary oxidation of benzene and its metabolites are mediated via cytochrome P-450 in the liver, although the role of secondary metabolism in the bone marrow is not clear. Toxicity is associated with the dihydroxy metabolites, hydroquinone and catechol, which concentrate in bone marrow. Hydroquinone and its terminal oxidation product, p-benzoquinone, have been demonstrated to be potent suppressors of cell growth in culture. Suppression of lymphocyte blastogenesis by these compounds is a sulfhydryl-dependent process and occurs at concentrations that do not result in cell death, or in detectable alterations in energy metabolism, intracellular glutathione concentration, or protein synthesis. Recent studies suggest that these compounds and other membrane-penetrating sulfyhdryl alkylating agents, such as N-ethylmaleimide and cytochalasin A, and endogenous regulatory molecules, such as soluble immune response suppressor (SIRS), interfere with microtubule assembly in vitro and selectively interfere with microtubule-dependent cell functions at identical concentrations. These agents appear to react with nucleophilic sulfhydryl groups essential for guanosine triphosphate binding to tubulin that are particularly sensitive to sulfhydryl-alkylating agents.

  19. Gaseous phase benzene decomposition by non-thermal plasma coupled with nano titania catalyst

    International Nuclear Information System (INIS)

    Synergistic effect of atmospheric non-thermal plasma generated by dielectric barrier discharge and nano titania photo catalyst for benzene decomposition was tested. The paper indicated the effect of photo catalyst on removal efficiency of benzene, the compare of photo catalyst characteristic in different high temperatures by heat treatment, analysis of by-products. The results showed that the effect of degradation was visible by added photo catalyst in the plasma reactor. When concentration of benzene was 600 mg/m3 and electric field strength was 10 kV/cm, the removal efficiency of benzene was increased up to 81 % without photo catalyst. At the same condition, the removal efficiency was increased to 15 % higher with photo catalyst. Nano titania crystal was anatase crystal in 450 degC heat treatment which is best for benzene removal. The plasma reactor packed with photo catalyst shows a better selectivity of carbon dioxide than that without photo catalyst. By-products are mostly carbon dioxide, water and a small quantity of carbon monoxide

  20. Electron beam treatment of high NOx concentration off-gases

    International Nuclear Information System (INIS)

    High concentration of NOx removal from simulated off-gases was investigated using electron beam (EB) technology. Simulated off-gases were prepared by combusting Polish light oil or nature gas with addition of NO from a NO gas cylinder. Irradiation was carried out under a ILU-6 accelerator. It was found that removal efficiency of NOx was influenced by inlet concentration of NO, temperature, SO2 concentration, absorbed dose and irradiation dose rate. Methods of enhancing NOx removal efficiency with additives using EB were also discussed. - Highlights: ? High concentrations of NOx removal from off-gases were studied under electron beam (EB) irradiation. ? Removal efficiency of NOx was increased with inlet concentration of NO, temperature, SO2 concentration and absorbed dose. ? Removal efficiency of NOx was influenced by irradiation dose rate of EB. ? Methods of enhancing NOx removal efficiency with additives using EB were also discussed.

  1. Substrate interactions during aerobic biodegradation of benzene.

    Science.gov (United States)

    Arvin, E; Jensen, B K; Gundersen, A T

    1989-12-01

    This study dealt with the interactions with benzene degradation of the following aromatic compounds in a mixed substrate: toluene, o-xylene, naphthalene, 1,4-dimethylnaphthalene, phenanthrene, and pyrrole. The experiment was performed as a factorial experiment with simple batch cultures. The effect of two different types of inocula was tested. One type of inoculum was grown on a mixture of aromatic hydrocarbons; the other was grown on a mixture of aromatic hydrocarbons and nitrogen-, sulfur-, and oxygen-containing aromatic compounds (NSO compounds), similar to some of the compounds identified in creosote waste. The culture grown on the aromatic hydrocarbons and NSO compounds was much less efficient in degrading benzene than the culture grown on only aromatic hydrocarbons. The experiments indicated that toluene- and o-xylene-degrading bacteria are also able to degrade benzene, whereas naphthalene-, 1,,4-dimethylnaphthalene-, and phenanthrene-degrading bacteria have no or very little benzene-degrading ability. Surprisingly, the stimulating effect of toluene and o-xylene was true only if the two compounds were present alone. In combination an antagonistic effect was observed, i.e., the combined effect was smaller than the sum from each of the compounds. The reason for this behavior has not been identified. Pyrrole strongly inhibited benzene degradation even at concentrations of about 100 to 200 micrograms/liter. Future studies will investigate the generality of these findings. PMID:2619308

  2. Optical diagnostic method for benzene detection in air

    Science.gov (United States)

    Alnis, J.; Revalde, G.; Vrublevskis, A.; Gavare, Z.

    2014-10-01

    In this paper we show our first results of research for creation a detector for benzene vapor and possibly other volatile organic compounds detection in air based on Zeeman atomic absorption technique. First the detailed study of benzene absorption spectra with high resolution spectrometer Jobin-Yvon 1000M was done. The absorption spectra of benzene were registered in the spectral range from 200-900 nm. More detailed analysis was done for the 240 - 260 nm spectral range to test a possibility to detect benzene by means of emission line of 254 nm of mercury.

  3. Phase II metabolism of benzene.

    OpenAIRE

    Schrenk, D.; Orzechowski, A.; Schwarz, L. R.; Snyder, R.; Burchell, B; Ingelman-sundberg, M.; Bock, K. W.

    1996-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-11-01

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

  5. Case study of elevated layers of high sulfate concentration

    International Nuclear Information System (INIS)

    During studies in August 1976 that were part of the Multi-State Atmospheric Power Production Pollutant Study (MAP3S), Alkezweeny et al., (1977) noted that in the Milwaukee urban plume, layers of relatively high sulfate concentrations occurred at high altitudes with respect to the boundary layer. This paper represents a progress report on studies undertaken to investigate possible causes for a bimodel vertical profile of sulfate concentrations. Data presented by Alkezweeny et al., (1977) serve as a basis for this study. Data from August 23, 1976, and August 24, 1978, indicate concentrations relatively high in sulfate, at 1000 and 6000 ft, respectively, with lower concentrations at lower altitudes. Concentrations of trace metals also indicate no peaks in the vertical concentration profiles above the surface. Initial studies of the high, elevated sulfate concentrations have centered on the August 23 measurements taken over southeast Wisconsin using synoptic data from the national weather service, emissions data from the national emissions data bank system (EPA), air quality data from the national air surveillance network (EPA), and satellite photographs from the EROS Data Center

  6. Effect of temperature and additives on the critical micelle concentration and thermodynamics of micelle formation of sodium dodecyl benzene sulfonate and dodecyltrimethylammonium bromide in aqueous solution: A conductometric study

    International Nuclear Information System (INIS)

    Highlights: • Specific conductance has been measured for surfactant–amino acid–water ternary system. • CMC and thermodynamic parameters have been evaluated for the studied system. • Effect of temperature and additives has been explored. • Hydrophobic and hydrophilic dehydration have been discussed in detail. • Different interactions occurring in such system have been explored from computed parameters. -- Abstract: Specific conductance of (0.3 to 3.0) mmol · kg?1 sodium dodecyl benzene sulfonate (SDBS) and (3.0 to 30.0) mmol · kg?1 dodecyltrimethylammonium bromide (DTAB) has been determined in water and in the presence of (0.01, 0.05 and 0.10) mol · kg?1 aqueous solution of glutamine/histidine/methionine at T = (293.15, 298.15, 303.15, 308.15 and 313.15) K. From the conductivity data, the critical micellar concentration (CMC) and thermodynamic parameters of micellization (?Gmo,?Hmo and ?Smo) have been computed by applying the mass action model. Enthalpy–entropy compensation effect has also been observed. The effect of amino acid on the micellar properties of SDBS and DTAB depends upon their nature, concentration, as well as on temperature and has been used to study the interactions present in the micellar systems. There occurs a gradual increase in the value of CMC with temperature in case of SDBS while in case of DTAB, it passes through a broad minimum and then tends to increase with increase in temperature. Increase of amino acid concentration is found to decrease CMC in both the surfactants. The ?Gmo values are negative and the feasibility of the micellization is found to increase with rise in temperature. The magnitude of hydrophilic and hydrophobic dehydration determines whether the CMC values increase or decrease with rise in temperature

  7. Hematotoxicity and carcinogenicity of benzene.

    OpenAIRE

    Aksoy, M.

    1989-01-01

    The hematotoxicity of benzene exposure has been well known for a century. Benzene causes leukocytopenia, thrombocytopenia, pancytopenia, etc. The clinical and hematologic picture of aplastic anemia resulting from benzene exposure is not different from classical aplastic anemia; in some cases, mild bilirubinemia, changes in osmotic fragility, increase in lactic dehydrogenase and fecal urobilinogen, and occasionally some neurological abnormalities are found. Electromicroscopic findings in some ...

  8. Microalgae Tolerance to High Concentrations of Carbon Dioxide: A Review

    Directory of Open Access Journals (Sweden)

    Fadhil M. Salih

    2011-07-01

    Full Text Available The increasing concentration of carbon dioxide (CO2 in the atmosphere is considered to be one of the main causes of the global warming problem. Moreover, there is an international movement to reduce the emission of CO2 by imposing different measures such as carbon tax. Biological CO2 fixation has been extensively investigated as part of efforts to solve the global warming problem. Microalgae are fast growing systems that can consume high quantities of CO2 to produce different types of biomass. The efficiency of microalgae is highly related to the concentration of CO2 in the growth atmosphere and the higher the concentration of CO2 the better is the growth and hence productivity. The present review aimed at shedding some light upon microalgal capability to sustain their viability and propagate under high CO2 concentration.

  9. Short-term monitoring of benzene air concentration in an urban area: a preliminary study of application of Kruskal-Wallis non-parametric test to assess pollutant impact on global environment and indoor.

    Science.gov (United States)

    Mura, Maria Chiara; De Felice, Marco; Morlino, Roberta; Fuselli, Sergio

    2010-01-01

    In step with the need to develop statistical procedures to manage small-size environmental samples, in this work we have used concentration values of benzene (C6H6), concurrently detected by seven outdoor and indoor monitoring stations over 12 000 minutes, in order to assess the representativeness of collected data and the impact of the pollutant on indoor environment. Clearly, the former issue is strictly connected to sampling-site geometry, which proves critical to correctly retrieving information from analysis of pollutants of sanitary interest. Therefore, according to current criteria for network-planning, single stations have been interpreted as nodes of a set of adjoining triangles; then, a) node pairs have been taken into account in order to estimate pollutant stationarity on triangle sides, as well as b) node triplets, to statistically associate data from air-monitoring with the corresponding territory area, and c) node sextuplets, to assess the impact probability of the outdoor pollutant on indoor environment for each area. Distributions from the various node combinations are all non-Gaussian, in the consequently, Kruskal-Wallis (KW) non-parametric statistics has been exploited to test variability on continuous density function from each pair, triplet and sextuplet. Results from the above-mentioned statistical analysis have shown randomness of site selection, which has not allowed a reliable generalization of monitoring data to the entire selected territory, except for a single "forced" case (70%); most important, they suggest a possible procedure to optimize network design. PMID:21169677

  10. Quantum chromodynamics quark benzene

    OpenAIRE

    Ping, Jialun; Deng, Chengrong; Wang, Fan; Goldman, T.

    2006-01-01

    A six-quark state with the benzene-like structure is proposed and studied based on color string model. The calculation with the quadratic confinement show that such structure has the lowest energy among the various hidden color six-quark structures proposed so far. Its possible effect on $NN$ scattering is discussed.

  11. Freeform solar concentrator with a highly asymmetric acceptance cone

    Science.gov (United States)

    Wheelwright, Brian; Angel, J. Roger P.; Coughenour, Blake; Hammer, Kimberly

    2014-10-01

    A solar concentrator with a highly asymmetric acceptance cone is investigated. Concentrating photovoltaic systems require dual-axis sun tracking to maintain nominal concentration throughout the day. In addition to collecting direct rays from the solar disk, which subtends ~0.53 degrees, concentrating optics must allow for in-field tracking errors due to mechanical misalignment of the module, wind loading, and control loop biases. The angular range over which the concentrator maintains circular tracks are often limited by elevation tracking performance. We show that a line-focus concentrator, composed of a parabolic trough primary reflector and freeform refractive secondary, can be tailored to have a highly asymmetric acceptance angle. The design is suitable for a tracker with excellent tracking accuracy in the elevation direction, and poor accuracy in the azimuthal direction. In the 1000X design given, when trough optical errors (2mrad rms slope deviation) are accounted for, the azimuthal acceptance angle is +/- 1.65°, while the elevation acceptance angle is only +/-0.29°. This acceptance angle does not include the angular width of the sun, which consumes nearly all of the elevation tolerance at this concentration level. By decreasing the average concentration, the elevation acceptance angle can be increased. This is well-suited for a pedestal alt-azimuth tracker with a low cost slew bearing (without anti-backlash features).

  12. High concentration honey chitosan electrospun nanofibers: Biocompatibility and antibacterial effects.

    Science.gov (United States)

    Sarhan, Wessam A; Azzazy, Hassan M E

    2015-05-20

    Honey nanofibers represent an attractive formulation with unique medicinal and wound healing advantages. Nanofibers with honey concentrations of honey concentrations to increase the antibacterial and wound healing effects. In this work, chitosan and honey (H) were cospun with polyvinyl alcohol (P) allowing the fabrication of nanofibers with high honey concentrations up to 40% and high chitosan concentrations up to 5.5% of the total weight of the fibers using biocompatible solvents (1% acetic acid). The fabricated nanofibers were further chemically crosslinked, by exposure to glutaraldehyde vapor, and physically crosslinked by heating and freezing/thawing. The new HP-chitosan nanofibers showed pronounced antibacterial activity against Staphylococcus aureus but weak antibacterial activity against Escherichia coli. The developed HP-chitosan nanofibers revealed no cytotoxicity effects on cultured fibroblasts. In conclusion, biocompatible, antimicrobial crosslinked honey/polyvinyl alcohol/chitosan nanofibers were developed which hold potential as effective wound dressing. PMID:25817652

  13. Lack of sensitivity of urinary trans,trans-muconic acid in determining low-level (ppb) benzene exposure in children.

    Science.gov (United States)

    Barbieri, Anna; Accorsi, Antonio; Raffi, Giovanni Battista; Nicoli, Luciana; Violante, Francesco Saverio

    2002-01-01

    Benzene is a widespread pollutant of which the main source in the outside environment is automotive traffic. Benzene is also present in cigarette smoke, and small quantities exist in drinking water and food; all of these sources contribute to pollution of indoor environments. Benzene exposure may be studied with biologic indicators. In the present study, the authors evaluated whether differences in urinary concentrations of trans,transmuconic acid (t,t-MA) were detectable in a sample of 150 children and if the chemical was correlated with environmental exposures to low levels of benzene. The children attended primary schools that had significantly different-but low-environmental benzene levels. Analysis of urinary t,t-MA was achieved with high-performance liquid chromatography (photodiode array detector), and analysis of passive air samplers for benzene was performed with gas chromatography-mass spectrometry. Statistical analysis (Kruskal-Wallis test) indicated that differences in urinary levels of t,t-MA in children from urban and rural areas were not statistically significant (p = .07), nor were there significant differences between children with and without relatives who smoked (p = .69). As has been shown in other studies of children and adults, results of our study evidenced (1) the difficulty of correlating concentrations of urinary biomarkers with environmental exposure to benzene at a parts-per-billion level (i.e., traffic and environmental tobacco smoke) and, consequently, (2) the lack of specificity of t,t-MA as a biological indicator for the study of a population's exposure. PMID:12507175

  14. Living with high concentrations of urea: They can!

    OpenAIRE

    Caterina Faggio; Francesca Trischitta; Agata Torre

    2012-01-01

    Marine elasmobranchs maintain their body fluid isoosmotic or slightly hyperosmotic to the external medium by the retention of large urea concentrations. This review focuses on the strategies adopted by these fishes to maintain a large outwardly direct concentration gradient of this osmolyte minimizing the loss across the main interfaces between body fluid and the external medium such as the gills, the kidney and the rectal gland, thus reducing the cost of making urea. The high plasma osmolari...

  15. Test of electron beam technology on Savannah River Laboratory low-activity aqueous waste for destruction of benzene, benzene derivatives, and bacteria

    International Nuclear Information System (INIS)

    High energy radiation was studied as a means for destroying hazardous organic chemical wastes. Tests were conducted at bench scale with a 60Co source, and at full scale (387 l/min) with a 1.5 MV electron beam source. Bench scale tests for both benzene and phenol included 32 permutations of water quality factors. For some water qualities, as much as 99.99% of benzene or 90% of phenol were removed by 775 krads of 60Co irradiation. Full scale testing for destruction of benzene in a simulated waste-water mix showed loss of 97% of benzene following an 800 krad dose and 88% following a 500 krad dose. At these loss rates, approximately 5 Mrad of electron beam irradiation is required to reduce concentrations from 100 g/l to drinking water quality (5 ?g/l). Since many waste streams are also inhabited by bacterial populations which may affect filtering operations, the effect of irradiation on those populations was also studied. 60Co and electron beam irradiation were both lethal to the bacteria studied at irradiation levels far lower than were necessary to remove organic contaminants

  16. Test of electron beam technology on Savannah River Laboratory low-activity aqueous waste for destruction of benzene, benzene derivatives, and bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Dougal, R.A. [Univ. of South Carolina, Columbia, SC (United States). Dept. of Electrical and Computer Engineering

    1993-08-01

    High energy radiation was studied as a means for destroying hazardous organic chemical wastes. Tests were conducted at bench scale with a {sup 60}Co source, and at full scale (387 l/min) with a 1.5 MV electron beam source. Bench scale tests for both benzene and phenol included 32 permutations of water quality factors. For some water qualities, as much as 99.99% of benzene or 90% of phenol were removed by 775 krads of {sup 60}Co irradiation. Full scale testing for destruction of benzene in a simulated waste-water mix showed loss of 97% of benzene following an 800 krad dose and 88% following a 500 krad dose. At these loss rates, approximately 5 Mrad of electron beam irradiation is required to reduce concentrations from 100 g/l to drinking water quality (5 {mu}g/l). Since many waste streams are also inhabited by bacterial populations which may affect filtering operations, the effect of irradiation on those populations was also studied. {sup 60}Co and electron beam irradiation were both lethal to the bacteria studied at irradiation levels far lower than were necessary to remove organic contaminants.

  17. High indoor radon concentrations in some Swedish waterworks

    International Nuclear Information System (INIS)

    High indoor radon concentrations in buildings used for water treatment are not uncommon. When raw water is processed in an open system radon escapes from the water to the indoor air of the premises. It is not unusual that the staff of the waterworks have their offices in the building where the water is processed. If large volumes of water are processed and the evaporated radon can reach the workplaces the indoor radon concentration can be very high even if the radon concentration of the raw water is moderate. Groundwaters from aquifers in bedrock and soil and surface water that has been infiltrated through deposits of sand or gravel have the potential to cause high indoor radon levels. In surface water emanating directly from a lake or a river the radon concentrations are normally too low to cause problems. Three waterworks in central Sweden have been studied, Ludvika, Fredriksberg and Kolbaeck. The radon concentrations in the raw water of these waterworks are from 85 Bq/l to 300 Bq/l. Average indoor radon concentrations exceeding 17,000 Bq/m3 have been measured in Ludvika with peaks of almost 37,000 Bq/m3. In Kolbaeck radon concentrations up to 56,000 Bq/m3 have been measured. It is quite possible that employees of waterworks can receive doses exceeding 20 mSv per year (calculated according to ICRP:s dose conversion convention). Measurements of radon and gamma radiation from the waterworks are reported and methods to lower the indoor radon concentrations are discussed. (author)

  18. Evolution of soot size distribution in premixed ethylene/air and ethylene/benzene/air flames: Experimental and modeling study

    Energy Technology Data Exchange (ETDEWEB)

    Echavarria, Carlos A.; Sarofim, Adel F.; Lighty, JoAnn S. [Department of Chemical Engineering, University of Utah, Salt Lake City, UT (United States); D' Anna, Andrea [Dipartimento di Ingegneria Chimica, Universita ' ' Federico II' ' di Napoli, Naples (Italy)

    2011-01-15

    The effect of benzene concentration in the initial fuel on the evolution of soot size distribution in ethylene/air and ethylene/benzene/air flat flames was characterized by experimental measurements and model predictions of size and number concentration within the flames. Experimentally, a scanning mobility particle sizer was used to allow spatially resolved and online measurements of particle concentration and sizes in the nanometer-size range. The model couples a detailed kinetic scheme with a discrete-sectional approach to follow the transition from gas-phase to nascent particles and their coagulation to larger soot particles. The evolution of soot size distribution (experimental and modeled) in pure ethylene and ethylene flames doped with benzene showed a typical nucleation-sized (since particles do not actually nucleate in the classical sense particle inception is often used in place of nucleation) mode close to the burner surface, and a bimodal behavior at greater height above burner (HAB). However, major features were distinguished between the data sets. The growth of nucleation and agglomeration-sized particles was faster for ethylene/benzene/air flames, evidenced by the earlier presence of bimodality in these flames. The most significant changes in size distribution were attributed to an increase in benzene concentration in the initial fuel. However, these changes were more evident for high temperature flames. In agreement with the experimental data, the model also predicted the decrease of nucleation-sized particles in the postflame region for ethylene flames doped with benzene. This behavior was associated with the decrease of soot precursors after the main oxidation zone of the flames. (author)

  19. Hyperbranched poly(benzimidazole-co-benzene) with honeycomb structure as a membrane for high-temperature proton-exchange membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Bhadra, Sambhu [Dept of Polymer and Nano Engineering, Chonbuk National University, Duckjin-dong 1Ga 664-14, Jeonju, Jeonbuk, 561-756 (Korea); Kim, Nam Hoon; Choi, Ji Sun [Department of Hydrogen and Fuel Cell Engineering, Chonbuk National University, Duckjin-dong 1Ga 664-14, Jeonju, Jeonbuk, 561-756 (Korea); Rhee, Kyong Yop [Department of Mechanical Engineering, Kyung Hee University, Yongin, 446-701 (Korea); Lee, Joong Hee [Dept of Polymer and Nano Engineering, Chonbuk National University, Duckjin-dong 1Ga 664-14, Jeonju, Jeonbuk, 561-756 (Korea); Department of Hydrogen and Fuel Cell Engineering, Chonbuk National University, Duckjin-dong 1Ga 664-14, Jeonju, Jeonbuk, 561-756 (Korea)

    2010-05-01

    Hyperbranched poly(benzimidazole-co-benzene) (PBIB) with a honeycomb structure is synthesized by condensation polymerization of trimesic acid (TMA) and 3,3'-diaminobenzidine (DAB) for use as a membrane high-temperature proton-exchange membrane fuel cells (HT-PEMFCs). The hyperbranched honeycomb structure of polybenzimidazole (PBI) has been introduced to impart higher mechanical strength to doped PBI membranes. The stress at break of the phosphoric acid doped PBIB (DPBIB) membrane (29 {+-} 3 MPa) is comparable with that of Nafion (28 {+-} 2 MPa) and much superior to doped PBI membranes. The DPBIB membrane exhibits lower proton conductivity than Nafion 115. On the other hand, the proton conductivity of Nafion 115 is enhanced with increase in relative humidity, whereas humidity has only a moderate effect on the proton conductivity of the DPBIB membrane. Consequently, the Nafion 115 membrane in a fuel cell cannot operate in the absence of humidity, whereas the DPBIB membrane can perform well. The power output of the DPBIB membrane in a fuel cell is superior under humid conditions than under dry conditions. The maximum power output from the DPBIB and Nafion 115 membranes is comparable under humid conditions. It is concluded that the DPBIB membrane, but not Nafion, is suitable for application in HT-PEMFCs. (author)

  20. Steel corrosion in anoxic mediums with high chloride concentrations

    International Nuclear Information System (INIS)

    Carbon steels are widely used in contact with chloride containing mediums, however most of the literature reports corrosion problems in solutions in contact with air, for example, sea water. There are other applications where the steel is in contact with freshwater in the absence of oxygen as is the case with materials for nuclear repositories or in petroleum production. These mediums can have varied composition but their corrosivity is usually related to the concentration of chlorides. There are no systematic studies in the literature about the influence of high chloride concentrations on the speed of steel corrosion for carbon steels in the absence of oxygen. Some work has been done using Raman and XPS spectroscopy, but these techniques have been carried out ex situ in samples submitted to the action of high chloride concentrations. This results in the appearance of corrosion products on the metal surface due to the oxidation of the surface from exposure to air before and during the use of these techniques, generating confusing and uncertain data. The lack of reliable data is due to the difficulty of applying these techniques in situ under very low oxygen conditions (less than 10 ppb) without allowing any air into the system. Since there are no studies in the literature about the influence of high concentrations of chloride on the corrosion speed of carbon steels in the absence of oxygen, this work aims to generate experimental data to evaluate the influence of hightal data to evaluate the influence of high concentrations of this anion on the corrosion speed of steel under anoxic conditions. The corrosivity of each solution was evaluated using electrochemical techniques such as corrosion potential, corrosion speed, anodic and cathodic polarization curves, cyclic voltammetries and electrochemical impedance spectroscopy to study the oxidation-reduction processes that occur with specific temperature, pH and chloride concentration conditions. Concentrated solutions of sodium chloride (50,000, 100,000 and 180,000 ppm of Cl-) were used in the absence of oxygen (concentration less than 10 ppb) and at 40oC0C and pH=7.5. The material chosen for this study was AISI 1018 steel. The results show that the corrosion speed of the carbon steel decreases with the increase in chloride concentrations and the increase in the steel's exposure time to the corrosive medium. This suggests that a high concentration of Cl- anions in the medium will provoke the adsorption of matter on the metal surface forming a homogeneous barrier that impedes corrosion by simply blocking the active reaction sites

  1. Intercomparison of passive microwave sea ice concentration retrievals over the high-concentration Arctic sea ice

    DEFF Research Database (Denmark)

    andersen, susanne; Tonboe, R.

    2007-01-01

    [1] Measurements of sea ice concentration from the Special Sensor Microwave Imager (SSM/I) using seven different algorithms are compared to ship observations, sea ice divergence estimates from the Radarsat Geophysical Processor System, and ice and water surface type classification of 59 wide-swath synthetic aperture radar (SAR) scenes. The analysis is confined to the high-concentration Arctic sea ice, where the ice cover is near 100%. During winter the results indicate that the variability of the SSM/I concentration estimates is larger than the true variability of ice concentration. Results from a trusted subset of the SAR scenes across the central Arctic allow the separation of the ice concentration uncertainty due to emissivity variations and sensor noise from other error sources during the winter of 2003-2004. Depending on the algorithm, error standard deviations from 2.5 to 5.0% are found with sensor noise between 1.3 and 1.8%. This is in accord with variability estimated from analysis of SSM/I time series. Algorithms, which primarily use 85 GHz information, consistently give the best agreement with both SAR ice concentrations and ship observations. Although the 85 GHz information is more sensitive to atmospheric influences, it was found that the atmospheric contribution is secondary to the influence of the surface emissivity variability. Analysis of the entire SSM/I time series shows that there are significant differences in trend between sea ice extent and area, using different algorithms. This indicates that long-term trends in surface and atmospheric properties, unrelated to sea ice concentration, influence the computed trends.

  2. Topical capsaicin (high concentration) for chronic neuropathic pain in adults.

    OpenAIRE

    Derry, S.; Sven-rice, A.; Cole, P.; Tan, T.; Moore, Ra

    2013-01-01

    BACKGROUND: Topical creams with capsaicin are used to treat peripheral neuropathic pain. Following application to the skin capsaicin causes enhanced sensitivity, followed by a period with reduced sensitivity and, after repeated applications, persistent desensitisation. High-concentration (8%) capsaicin patches were developed to increase the amount of capsaicin delivered; rapid delivery was thought to improve tolerability because cutaneous nociceptors are 'defunctionalised' quickly. The single...

  3. Investigation of the areas of high radon concentration in Gyeongju

    International Nuclear Information System (INIS)

    The aim of this study was to survey the radon concentrations at 21 elementary schools in Gyeongju, Republic of Korea, to identify those schools with high radon concentrations. Considering their geological characteristics and the preliminary survey results, three schools were finally placed under close scrutiny. For these three schools, continuous measurements over 48 h were taken at the principal's and administration office. The radon concentrations at one school, Naenam, exceeded the action level (148 Bq/m3) established by the U.S. EPA, while those at the other two schools were below that level. - Highlights: • Preliminary measurements of the indoor radon concentrations were performed at the auditoriums in 23 elementary schools in Gyeongju. • Considering the geological characteristics and preliminary survey results, three elementary schools were screened for closer scrutiny. • For the three schools, continuous measurements were made at their principal's and administration offices over 48-h period. • The scrutiny revealed one elementary school of high radon concentration much higher than the U.S. EPA action level

  4. Mobil-Badger technologies for benzene reduction in gasoline

    Energy Technology Data Exchange (ETDEWEB)

    Goelzer, A.R.; Ram, S.; Hernandez, A. (Badger Engineers, Inc., Cambridge, MA (United States)); Chin, A.A.; Harandi, M.N.; Smith, C.M. (Mobil Research and Development Corp., Princeton, NJ (United States) Mobil Research and Development Corp., Paulsboro, NJ (United States))

    1993-01-01

    Many refiners will need to reduce the barrels per day of benzene entering the motor gasoline pool. Mobil and Badger have developed and now jointly license three potential refinery alternatives to conventional benzene hydrosaturation to achieve this: Mobil Benzene Reduction, Ethylbenzene and Cumene. The Mobil Benzene Reduction Process (MBR) uses dilute olefins in FCC offgas to extensively alkylate dilute benzene as found in light reformate, light FCC gasoline, or cyclic C[sub 6] naphtha. MBR raises octanes and lowers C[sub 5]+ olefins. MBR does not involve costly hydrogen addition. The refinery-based Mobil/Badger Ethylbenzene Process reacts chemical-grade benzene extracted from light reformate with dilute ethylene found in treated FCC offgas to make high-purity ethylbenzene. EB is the principal feedstock for the production of styrene. The Mobil/Badger Cumene Process alkylates FCC-derived dilute propylene and extracted benzene to selectively yield isopropyl benzene (cumene). Cumene is the principal feedstock for the production of phenol. All three processes use Mobil developed catalysts.

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

    Science.gov (United States)

    Weisel, Clifford P

    2010-03-19

    Benzene has been measured throughout the environment and is commonly emitted in several industrial and transportation settings leading to widespread environmental and occupational exposures. Inhalation is the most common exposure route but benzene rapidly penetrates the skin and can contaminant water and food resulting in dermal and ingestion exposures. While less toxic solvents have been substituted for benzene, it still is a component of petroleum products, including gasoline, and is a trace impurity in industrial products resulting in continued sub to low ppm occupational exposures, though higher exposures exist in small, uncontrolled workshops in developing countries. Emissions from gasoline/petrochemical industry are its main sources to the ambient air, but a person's total inhalation exposure can be elevated from emissions from cigarettes, consumer products and gasoline powered engines/tools stored in garages attached to homes. Air samples are collected in canisters or on adsorbent with subsequent quantification by gas chromatography. Ambient air concentrations vary from sub-ppb range, low ppb, and tens of ppb in rural/suburban, urban, and source impacted areas, respectively. Short-term environmental exposures of ppm occur during vehicle fueling. Indoor air concentrations of tens of ppb occur in microenvironments containing indoor sources. Occupational and environmental exposures have declined where regulations limit benzene in gasoline (<1%) and cigarette smoking has been banned from public and work places. Similar controls should be implemented worldwide to reduce benzene exposure. Biomarkers of benzene used to estimate exposure and risk include: benzene in breath, blood and urine; its urinary metabolites: phenol, t,t-muconic acid (t,tMA) and S-phenylmercapturic acid (sPMA); and blood protein adducts. The biomarker studies suggest benzene environmental exposures are in the sub to low ppb range though non-benzene sources for urinary metabolites, differences in metabolic rates compared to occupational or animal doses, and the presence of polymorphisms need to be considered when evaluating risks from environmental exposures to individuals or potentially susceptible populations. PMID:20056112

  6. JV Task 86 - Identifying the Source of Benzene in Indoor Air Using Different Compound Classes from TO-15 Data

    Energy Technology Data Exchange (ETDEWEB)

    Steven B. Hawthorne

    2007-04-15

    Volatile organic compound (VOC) data that had already been collected using EPA method TO-15 at four different sites under regulatory scrutiny (a school, strip mall, apartment complex, and business/residential neighborhood) were evaluated to determine whether the source of indoor air benzene was outdoor air or vapor intrusion from contaminated soil. Both the use of tracer organics characteristic of different sources and principal component statistical analysis demonstrated that the source of indoor air at virtually all indoor sampling locations was a result of outdoor air, and not contaminated soil in and near the indoor air-sampling locations. These results show that proposed remediation activities to remove benzene-contaminated soil are highly unlikely to reduce indoor air benzene concentrations. A manuscript describing these results is presently being prepared for submission to a peer-reviewed journal.

  7. Potential metallurgical treatment of copper concentrates with high arsenic contents

    Scientific Electronic Library Online (English)

    I, Mihajlovic; N, Strbac; D, Nikolic; Z, Zivkovic.

    2011-06-01

    Full Text Available SYNOPSIS This paper investigates a potential method for arsenic removal from copper concentrates using hypochlorite leaching. The problems concerning pyrometallurgical processing of copper concentrates with high arsenic contents are discussed. A possible solution to the problem by leaching of natura [...] l enargite crystals with sodium hypochlorite under alkaline oxidizing conditions, with enargite converted into crystalline CuO and the soluble arsenic forming AsO4(3-), was experimentally investigated and results are presented. Kinetic parameters were calculated for enargite leaching, using a model-free approach. Advanced isoconversional methods were used to investigate the dependence of activation energy (Ea) on reaction rate (?).

  8. Nonlinear diffusion in Acetone-Benzene Solution

    CERN Document Server

    Obukhovsky, Vjacheslav V

    2010-01-01

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

  9. Nonlinear diffusion in Acetone-Benzene Solution

    OpenAIRE

    Obukhovsky, Vjacheslav V.; Nikonova, Viktoriya V.

    2010-01-01

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

  10. Biomarkers of environmental benzene exposure.

    OpenAIRE

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

    1996-01-01

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

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

    International Nuclear Information System (INIS)

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

  12. Evaluation of seawater contamination with benzene, toluene and xylene in EHE Ubatuba Region and study of their degradation by ionizing radiation

    International Nuclear Information System (INIS)

    A major concern with leaking petroleum is the environmental contamination by 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 xylenes, and their removal by exposure to 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 headspace concentrator with MSGC detector. The minimal detected limits (MDL) obtained at FIDGC were of 0.50 ?g/L for benzene, 0.70 /L for toluene, and 1.54 /L for xylenes, and the obtained experimental variability was 15%. While the concentrator type Headspace system with MS detector showed higher MDL, about of 9.30 mg/L for benzene, 8.50 mg/L for toluene, and 9.80 mg/L for xylenes, and 10% of experimental variability. In the studied area the benzene concentration varied from 1.0 ?g/L to 2.0 ?g/L, the concentration of toluene varied from 60Co. The results showed 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. For toluene the removal were from 20% to 60% with 15 kGy and xylenes were removed from 20% to 80% with 15 kGy and similar concentrations. (author)

  13. Measurements of 7Be radioactivity concentrations in high altitude air

    International Nuclear Information System (INIS)

    Preliminary measurements of the 7Be radioactivity concentrations in high altitude air were made between April 1984 and March 1985 in order to check the possibility of use for the analysis of the measured gross beta concentrations. Airborne dusts were collected with a filter type air sampler attached to the F-4EJ aircraft. The measurement of the 7Be radioactivity in the filters was made by gamma-ray spectrometry with a Ge(Li) detector. The results ranging from 0.03 to 5 pCi/m3 are in approximate agreement with the calculated values using the equation derived by B. Peters. Comparing the results of 7Be with the gross beta activity concentrations, it is shown that observations of 7Be is helpful in the study of environmental radioactivity as a tracer for air circulation. (author)

  14. Life at high salt concentrations, intracellular KCl concentrations, and acidic proteomes

    Directory of Open Access Journals (Sweden)

    AharonOren

    2013-11-01

    Full Text Available Extremely halophilic microorganisms that accumulate KCl for osmotic balance (the Halobacteriaceae, Salinibacter have a large excess of acidic amino acids in their proteins. This minireview explores the occurrence of acidic proteomes in halophiles of different physiology and phylogenetic affiliation. For fermentative bacteria of the order Halanaerobiales, known to accumulate KCl, an acidic proteome was predicted. However, this is not confirmed by genome analysis. The reported excess of acidic amino acids is due to a high content of Gln and Asn, which yield Glu and Asp upon acid hydrolysis. The closely related Halorhodospira halophila and Halorhodospira halochloris use different strategies to cope with high salt. The first has an acidic proteome and accumulates high KCl concentrations at high salt concentrations; the second does not accumulate KCl and lacks an acidic proteome. Acidic proteomes can be predicted from the genomes of some moderately halophilic aerobes that accumulate organic osmotic solutes (Halomonas elongata, Chromohalobacter salexigens and some marine bacteria. Based on the information on cultured species it is possible to understand the pI profiles predicted from metagenomic data from hypersaline environments.

  15. Life at high salt concentrations, intracellular KCl concentrations, and acidic proteomes.

    Science.gov (United States)

    Oren, Aharon

    2013-01-01

    Extremely halophilic microorganisms that accumulate KCl for osmotic balance (the Halobacteriaceae, Salinibacter) have a large excess of acidic amino acids in their proteins. This minireview explores the occurrence of acidic proteomes in halophiles of different physiology and phylogenetic affiliation. For fermentative bacteria of the order Halanaerobiales, known to accumulate KCl, an acidic proteome was predicted. However, this is not confirmed by genome analysis. The reported excess of acidic amino acids is due to a high content of Gln and Asn, which yield Glu and Asp upon acid hydrolysis. The closely related Halorhodospira halophila and Halorhodospira halochloris use different strategies to cope with high salt. The first has an acidic proteome and accumulates high KCl concentrations at high salt concentrations; the second does not accumulate KCl and lacks an acidic proteome. Acidic proteomes can be predicted from the genomes of some moderately halophilic aerobes that accumulate organic osmotic solutes (Halomonas elongata, Chromohalobacter salexigens) and some marine bacteria. Based on the information on cultured species it is possible to understand the pI profiles predicted from metagenomic data from hypersaline environments. PMID:24204364

  16. Particle characterisation in highly concentrated dispersions using ultrasonic backscattering method.

    Science.gov (United States)

    Weser, Robert; Wöckel, Sebastian; Wessely, Benno; Hempel, Ulrike

    2013-03-01

    Determining particle size and concentration in highly concentrated suspensions and emulsions is challenging, especially under process conditions. In general, ultrasound therefore can be used for particle characterisation due to the ability of sound waves to pass opaque dispersions, whereas optical detection principles mostly are limited to low particulate contents. An established acoustic method, the ultrasonic attenuation spectroscopy, uses a transmission setup for measuring the attenuation of a dispersion. A major drawback of this measurement method is caused by the fact, that the measuring gap tends to plug, which again limits the inline capability. To overcome this limitation, an ultrasonic reflection setup is used for gathering the sound waves, which are reflected, respectively backscattered by the dispersion. Statistically analysing the corresponding backscattering signal yields the sound attenuation as well as a scattering intensity equivalent. Both measurement parameters can be shown to be sensitive against particle size and concentration. Based on a single scattering theory, a semi-empirical approach is presented for interpretation of measurement results with respect to particle size and concentration. Measurements, performed on a glass beads in water dispersion, show good agreement with theory for dimensionless wave number 0.1concentrations up to 30 vol.%. PMID:23212046

  17. BENZENE OXIDE PROTEIN ADDUCTS AS BIOMARKERS OF BENZENE EXPOSURE

    Science.gov (United States)

    Benzene is known to be hematotoxic and carcinogenic in animals and humans. While metabolism is required for toxicity, the identity of the ultimate carcinogen(s) remains unknown. Benzene oxide (BO) is the first and most abundant of the metabolites, but very little is known about...

  18. Anaerobic degradation of benzene by marine sulfate-reducing bacteria

    Science.gov (United States)

    Musat, Florin; Wilkes, Heinz; Musat, Niculina; Kuypers, Marcel; Widdel, Friedrich

    2010-05-01

    Benzene, the archetypal aromatic hydrocarbon is a common constituent of crude oil and oil-refined products. As such, it can enter the biosphere through natural oil seeps or as a consequence of exploitation of fossil fuel reservoirs. Benzene is chemically very stable, due to the stabilizing aromatic electron system and to the lack of functional groups. Although the anaerobic degradation of benzene has been reported under denitrifying, sulfate-reducing and methanogenic conditions, the microorganisms involved and the initial biochemical steps of degradation remain insufficiently understood. Using marine sediment from a Mediterranean lagoon a sulfate-reducing enrichment culture with benzene as the sole organic substrate was obtained. Application of 16S rRNA gene-based methods showed that the enrichment was dominated (more than 85% of total cells) by a distinct phylotype affiliated with a clade of Deltaproteobacteria that include degraders of other aromatic hydrocarbons, such as naphthalene, ethylbenzene and m-xylene. Using benzoate as a soluble substrate in agar dilution series, several pure cultures closely related to Desulfotignum spp. and Desulfosarcina spp. were isolated. None of these strains was able to utilize benzene as a substrate and hybridizations with specific oligonucleotide probes showed that they accounted for as much as 6% of the total cells. Incubations with 13C-labeled benzene followed by Halogen in situ Hybridization - Secondary Ion Mass Spectroscopy (HISH-SIMS) analysis showed that cells of the dominant phylotype were highly enriched in 13C, while the accompanying bacteria had little or no 13C incorporation. These results demonstrate that the dominant phylotype was indeed the apparent benzene degrader. Dense-cell suspensions of the enrichment culture did not show metabolic activity toward added phenol or toluene, suggesting that benzene degradation did not proceed through anaerobic hydroxylation or methylation. Instead, benzoate was identified in analyses of metabolites with benzene-grown cultures, suggesting an activation of benzene via carboxylation.

  19. Achieving High Dopant Concentrations in Si: First Principles Simulations

    Energy Technology Data Exchange (ETDEWEB)

    Centoni, S A; Sadigh, B; Caturla, M J; Gilmer, G H; Diaz de la Rubia, T

    2002-08-12

    In this paper we discuss methods to obtain high dopant concentrations during processing of Si devices. The possibility of increasing the solubility of B in Si by misfit stress is investigated. The enthalpy of B atoms is calculated, with and without stress, using density functional theory. A second approach, the trapping of excess dopant atoms during deposition of Si, is also considered. For this purpose, the enthalpies of several dopant species in sites near the surface are calculated.

  20. Relaxation of a highly concentrated electron beam in a plasma

    International Nuclear Information System (INIS)

    The electron energy distribution is determined to be anisotropic in a low-temperature plasma, when it is far from equilibrium. This leads to a kinetic instability of the highly concentrated beam in rarefied and dense plasmas over a wide range of the Knudsen parameter, The experimental criterion of threshold is true over a wide range of the Knudsen parameter. The beam isotropisation in plasma oscillations is shown to be realised simultaneously with the energy relaxation. (author)

  1. 300 sun light engine for high concentrator application studies

    Science.gov (United States)

    Chen, Anderson; Zadrovicz, Katy; Jarzebiak, Richard; Degroff, John; Park, John H.

    2014-10-01

    A solar simulator capable of producing an irradiance of 300 suns is reported. Technical challenges were not limited to optical design; developing a methodology to measuring 300 suns was difficult. This document reports on the design of the custom fabricated solar simulator, the measurement methodology for high-powered solar concentrator measurements and empirical results validating the desired simulated power density as well as the irradiance stability, spectral accuracy, beam uniformity and irradiance beam size.

  2. Biodegradation studies of oil sludge containing high hydrocarbons concentration

    Energy Technology Data Exchange (ETDEWEB)

    Olguin-Lora, P.; Munoz-Colunga, A.; Castorena-Cortes, G.; Roldan-Carrillo, T.; Quej Ake, L.; Reyes-Avila, J.; Zapata-Penasco, I.; Marin-Cruz, J.

    2009-07-01

    Oil industry has a significant impact on environment due to the emission of, dust, gases, waste water and solids generated during oil production all the way to basic petrochemical product manufacturing stages. the aim of this work was to evaluate the biodegradation of sludge containing high hydrocarbon concentration originated by a petroleum facility. A sludge sampling was done at the oil residuals pool (ORP) on a gas processing center. (Author)

  3. Biodegradation studies of oil sludge containing high hydrocarbons concentration

    International Nuclear Information System (INIS)

    Oil industry has a significant impact on environment due to the emission of, dust, gases, waste water and solids generated during oil production all the way to basic petrochemical product manufacturing stages. the aim of this work was to evaluate the biodegradation of sludge containing high hydrocarbon concentration originated by a petroleum facility. A sludge sampling was done at the oil residuals pool (ORP) on a gas processing center. (Author)

  4. Hematotoxicity and carcinogenicity of benzene

    Energy Technology Data Exchange (ETDEWEB)

    Aksoy, M. (Scientific and Technical Research Council of Turkey, Kocaeli (Turkey))

    1989-07-01

    The hematotoxicity of benzene exposure has been well known for a century. Benzene causes leukocytopenia, thrombocytopenia, pancytopenia, etc. The clinical and hematologic picture of aplastic anemia resulting from benzene exposure is not different from classical aplastic anemia; in some cases, mild bilirubinemia, changes in osmotic fragility, increase in lactic dehydrogenase and fecal urobilinogen, and occasionally some neurological abnormalities are found. Electromicroscopic findings in some cases of aplastic anemia with benzene exposure were similar to those observed by light microscopy. Benzene hepatitis-aplastic anemia syndrome was observed in a technician with benzene exposure. Ten months after occurrence of hepatitis B, a severe aplastic anemia developed. The first epidemiologic study proving the leukemogenicity of benzene was performed between 1967 and 1973 to 1974 among shoe workers in Istanbul. The incidence of leukemia was 13.59 per 100,000, which is a significant increase over that of leukemia in the general population. Following the prohibition and discontinuation of the use of benzene in Istanbul, there was a striking decrease in the number of leukemic shoe workers in Istanbul. In 23.7% of the series, consisting of 59 leukemic patients with benzene exposure, there was a preceding pancytopenic period. Furthermore, a familial connection was found in 10.2% of them. The 89.8% of the series showed the findings of acute leukemia. The possible factors that may determine the types of leukemia in benzene toxicity are discussed. The possible role of benzene exposure is presented in the development of malignant lymphoma, multiple myeloma, and lung cancer.

  5. Magnetoresistance of Si(001) MOSFETs with high concentration of electrons

    CERN Document Server

    Smrcka, L; Schemenchinskii, S G; Vasek, P; Jurka, V

    2003-01-01

    We present an experimental study of electron transport in inversion layers of high-mobility Si(001) samples with occupied excited subbands. The second series of oscillations, observed in addition to the main series of Shubnikov-de Hass oscillations, is tentatively attributed to the occupation of a subband associated with the $E_{0'}$ level. Besides, a strong negative magnetoresistance and nonlinear field dependence of the Hall resistance accompany the novel oscillations at high carrier concentrations. The heating of the 2D electron layers leads to suppression of the observed anomalies.

  6. Modeling the Effect of High Concentration Gradients on Hydrodynamic Dispersion

    Science.gov (United States)

    Sarioglu, S. M.; Copty, N.

    2008-12-01

    The hydrodynamic dispersion of contaminants in the subsurface is commonly described by Fick's Law which expresses the dispersive mass flux as a linear function of the concentration gradient. However, recent research has shown that under high concentration gradient (HCG) conditions -- as encountered for example in salt formations -- the relationship deviates from linearity. To account for this deviation, various modifications of Fick's Law have been proposed based on experiments that generally considered stable displacements of single, non-reactive species in saturated, homogeneous porous media. In this study, a computer model which includes the modified Fick's Law proposed by Hassanizadeh and Leijnse (1995) is developed. The non-linear model simulates the coupled flow and multispecies transport in heterogeneous two-dimensional porous media for different flow and concentration gradient conditions. Various numerical techniques for solving the governing non-linear partial differential equations are evaluated. The model is applied to a hypothetical problem where the hydraulic conductivity is defined as a Gaussian random spatial function. To assess the impact of HCG on transport, breakthrough curves for heterogeneous porous media under Fickian and non-Fickian assumptions are simulated. The results show that non-Fickian transport due to HCG may have a significant impact on the simulated travel times and peak concentrations. The implications of these numerical results on laboratory and field scale experiments involving HCG are discussed.

  7. Fabrication procedures for manufacturing high uranium concentration dispersion fuel elements

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Jose Antonio Batista de; Durazzo, Michelangelo, E-mail: jasouza@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    IPEN developed and made available for routine production the technology for manufacturing dispersion type fuel elements for use in research reactors. However, the fuel produced at IPEN is limited to the uranium concentration of 3.0 g U/c m3 by using the U{sub 3}Si{sub 2}-Al dispersion. Increasing the uranium concentration of the fuel is interesting by the possibility of increasing the reactor core reactivity and lifetime of the fuel. It is possible to increase the concentration of uranium in the fuel up to the technological limit of 4.8 g U/c m3 for the U{sub 3}Si{sub 2}-Al dispersion, which is well placed around the world. This new fuel will be applicable in the new Brazilian- Multipurpose Reactor RMB. This study aimed to develop the manufacturing process of high uranium concentration fuel, redefining the procedures currently used in the manufacture of IPEN. This paper describes the main procedures adjustments that will be necessary. (author)

  8. Fabrication procedures for manufacturing high uranium concentration dispersion fuel elements

    International Nuclear Information System (INIS)

    IPEN developed and made available for routine production the technology for manufacturing dispersion type fuel elements for use in research reactors. However, the fuel produced at IPEN is limited to the uranium concentration of 3.0 g U/c m3 by using the U3Si2-Al dispersion. Increasing the uranium concentration of the fuel is interesting by the possibility of increasing the reactor core reactivity and lifetime of the fuel. It is possible to increase the concentration of uranium in the fuel up to the technological limit of 4.8 g U/c m3 for the U3Si2-Al dispersion, which is well placed around the world. This new fuel will be applicable in the new Brazilian- Multipurpose Reactor RMB. This study aimed to develop the manufacturing process of high uranium concentration fuel, redefining the procedures currently used in the manufacture of IPEN. This paper describes the main procedures adjustments that will be necessary. (author)

  9. Virus filtration of high-concentration monoclonal antibody solutions.

    Science.gov (United States)

    Marques, Bruno F; Roush, David J; Göklen, Kent E

    2009-01-01

    The ability to process high-concentration monoclonal antibody solutions (> 10 g/L) through small-pore membranes typically used for virus removal can improve current antibody purification processes by eliminating the need for feed stream dilution, and by reducing filter area, cycle-time, and costs. In this work, we present the screening of virus filters of varying configurations and materials of construction using MAb solutions with a concentration range of 4-20 g/L. For our MAbs of interest-two different humanized IgG1s-flux decay was not observed up to a filter loading of 200 L/m(2) with a regenerated cellulose hollow fiber virus removal filter. In contrast, PVDF and PES flat sheet disc membranes were plugged by solutions of these same MAbs with concentrations >4 g/L well before 50 L/m(2). These results were obtained with purified feed streams containing XMuLV and MMV) confirm the ability of hollow fiber membranes with 19 +/- 2 nm pore size to achieve at least 3-4 LRV, independent of MAb concentration, over the range examined. PMID:19353736

  10. Variability of benzene exposure among filling station attendants

    International Nuclear Information System (INIS)

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

  11. Effect of electron and positive hole scavenger on positronium formation in benzene and cyclohexane

    International Nuclear Information System (INIS)

    The changes of O-Ps intensity in benzene and cyclohexane solutions in the presence of different concentrations of electron scavenger (CCl4) and positive hole scavenger (pyridine) have been investigated. The results show that mobilities of both electron and positive ion in cyclohexane are very high. Their mobilities in benzene are also high but less than that in cyclohexane. The fitting equation for the enhancement of O-Ps intensity in the presence of hole scavenger was derived, which shows that enhancement or inhibition of O-Ps intensity are consequences of the competition of the two processes of scavenging electron and scavenging positive ion. The absolute amount of enhancement of O-Ps intensity is not only related to the scavenging rate but also to the O-Ps intensity in pure positive hole scavenger. (author)

  12. Optical design considerations for high-concentration photovoltaics

    Science.gov (United States)

    Garboushian, Vahan; Gordon, Robert

    2006-08-01

    Over the past 15 years, major advances in Concentrating Photovoltaics (CPV) have been achieved. Ultra-efficient Si solar cells have produced commercial concentration systems which are being fielded today and are competitively priced. Advanced research has primarily focused on significantly more efficient multi-junction solar cells for tomorrow's systems. This effort has produced sophisticated solar cells that significantly improve power production. Additional performance and cost improvements, especially in the optical system area and system integration, must be made before CPV can realize its ultimate commercial potential. Structural integrity and reliability are vital for commercial success. As incremental technical improvements are made in solar cell technologies, evaluation and 'fine-tuning' of optical systems properly matched to the solar cell are becoming increasingly necessary. As we move forward, it is increasingly important to optimize all of the interrelated elements of a CPV system for high performance without sacrificing the marketable cost and structural requirements of the system. Areas such as wavelength absorption of refractive optics need to be carefully matched to the solar cell technology employed. Reflective optics require advanced engineering models to insure uniform flux distribution without excessive losses. In Situ measurement of the 'fine-grain' improvements are difficult as multiple variables such as solar insolation, temperature, wind, altitude, etc. infringe on analytical data. This paper discusses design considerations based on 10 years of field trials of high concentration systems and their relevance for tomorrow's advanced CPV systems.

  13. Prediction of colloidal stability of high concentration protein formulations.

    Science.gov (United States)

    Garidel, Patrick; Blume, Alfred; Wagner, Michael

    2014-01-01

    Abstract A major aspect determining the colloidal properties of proteins in solution is the interaction between them and with surrounding molecules. These interactions can be described by the concentration dependency of the protein diffusivity (kD), as derived by dynamic light scattering and was determined for different solutions of monoclonal antibodies varying in pH, ionic strength and presence/absence of co-solute(s). Concerning colloidal stability, protein solutions of different kD values are evaluated, based on their initial solution opalescence, to assess protein association. The current investigation shows that solution conditions with large kD values, indicating high repulsive protein-protein interactions, show lower initial opalescence, compared to solution conditions with low kD values. Upon applying stirring stress, to assess colloidal stability, the trend is such that, the higher kD values are, the more stable the protein solutions are, as long as the thermodynamic and conformational stability is not impaired. Besides, kD allows ranking of solution conditions for highly concentrated immunoglobulin solutions up to concentrations of ?200?mg?mL(-1) with regard to protein self-association and thus opalescent properties. The present study shows that the protein interaction parameter kD can be used as a surrogate parameter for a qualitative prediction of protein association and, thus, colloidal protein stability. PMID:24392929

  14. Liver imaging with MDCT and high concentration contrast media

    International Nuclear Information System (INIS)

    Liver imaging has advanced greatly over the last 10 years with helical CT capability and more recently the addition of multidetector-row CT (MDCT). Multidetector CT technology facilitates imaging at faster speeds with improved image quality and less breathing artifact [Abdom. Imaging 25 (2000) 643]. Exquisite three-dimensional data sets can be obtained with thin collimation providing improved lesion detection, multiplanar imaging, and the ability to perform CT angiography of the liver and mesenteric vessels. New challenges arise with this advance in technology including safety considerations. The radiation dose to the patient has increased with MDCT and this is compounded by the ability to perform multi-phase liver imaging. Furthermore, issues of contrast media administration require reconsideration including optimal timing and rate of administration, the total volume of contrast needed and the ideal iodine concentration of the contrast media. Recently, the use of high concentration contrast media (HCCM) has been explored and study results to date will be reviewed

  15. Separations of substituted benzenes and polycyclic aromatic hydrocarbons using normal- and reverse-phase high performance liquid chromatography with UiO-66 as the stationary phase.

    Science.gov (United States)

    Zhao, Wei-Wei; Zhang, Chao-Yan; Yan, Zeng-Guang; Bai, Li-Ping; Wang, Xiayan; Huang, Hongliang; Zhou, You-Ya; Xie, Yabo; Li, Fa-Sheng; Li, Jian-Rong

    2014-11-28

    Metal-organic frameworks (MOFs) have great potential for applications in chromatography due to their highly tailorable porous structures and unique properties. In this work, the stable MOF UiO-66 was evaluated as both a normal-phase (NP-) and a reverse-phase (RP-) stationary phase in the high performance liquid chromatography (HPLC) to separate substituted benzenes (SBs) and polycyclic aromatic hydrocarbons (PAHs). It was found that the mobile phase composition has a significant effect on the HPLC separation. Baseline RP-HPLC separations of xylene isomers; naphthalene and anthracene; naphthalene and chrysene; and naphthalene, fluorene, and chrysene were achieved using MeOH/H2O ratios of 80:20, 75:25, 85:15, and 75:25, respectively, on the UiO-66 column. Similarly, baseline NP-HPLC separations of xylene isomers and ethylbenzene; ethylbenzene, styrene, o-xylene, and m-xylene; and several PAHs were also obtained on the UiO-66 column with different mobile phase compositions. The relative standard deviations (RSDs) of retention time, peak height, peak area, and half peak width for five replicate separations of the tested analytes were within the ranges 0.2-0.4%, 0.2-1.6%, 0.7-3.9%, 0.4-1.1%, respectively. We also evaluated other critical HPLC parameters, including injected sample mass, column temperature, and the thermodynamic characters of both the RP-HPLC and the NP-HPLC separation processes. It was confirmed that the separation of SBs on a UiO-66 column was an exothermic process, controlled by both enthalpy change (?H) and entropy change (?S). The reverse shape selectivity, size selectivity, stacking effect, and electrostatic force played vital roles in the separations of these analytes. To the best of our knowledge, this method is one of the very few examples of using MOFs as the stationary phase in both NP-HPLC and RP-HPLC. MOF-based stationary phases may thus be applied in the separations and analyses of SBs and PAHs in environmental samples. PMID:25454136

  16. Fabrication procedures for manufacturing high uranium concentration dispersion fuel elements

    International Nuclear Information System (INIS)

    IPEN-CNEN/SP developed the technology to produce the dispersion type fuel elements for research reactors and made it available for routine production. Today, the fuel produced in IPEN-CNEN/SP is limited to the uranium concentration of 3.0 gU/cm3 for U3Si2-Al dispersion-based and 2.3 gU/cm3 for U3O8-Al dispersion. The increase of uranium concentration in fuel plates enables the reactivity of the reactor core reactivity to be higher and extends the fuel life. Concerning technology, it is possible to increase the uranium concentration in the fuel meat up to the limit of 4.8 gU/cm3 in U3Si2-Al dispersion and 3.2 gU/cm3 U3O8-Al dispersion. These dispersions are well qualified worldwide. This work aims to develop the manufacturing process of both fuel meats with high uranium concentrations, by redefining the manufacturing procedures currently adopted in the Nuclear Fuel Center of IPEN-CNEN/SP. Based on the results, it was concluded that to achieve the desired concentration, it is necessary to make some changes in the established procedures, such as in the particle size of the fuel powder and in the feeding process inside the matrix, before briquette pressing. These studies have also shown that the fuel plates, with a high concentration of U3Si2-Al, met the used specifications. On the other hand, the appearance of the microstructure obtained from U3O8-Al dispersion fuel plates with 3.2 gU/cm3 showed to be unsatisfactory, due to the considerably significant porosity observed. The developed fabrication procedure was applied to U3Si2 production at 4.8 gU/cm3, with enriched uranium. The produced plates were used to assemble the fuel element IEA-228, which was irradiated in order to check its performance in the IEA-R1 reactor at IPEN-CNEN/SP. These new fuels have potential to be used in the new Brazilian Multipurpose Reactor - RMB. (author)

  17. Spectroscopic properties of fluorophosphate glass with high Er3+ concentration

    Science.gov (United States)

    Liao, M.; Hu, L.; Duan, Z.; Zhang, L.; Wen, L.

    2007-01-01

    Fluorophosphate glass with 4 mol. % ErF3 content was prepared. The different scanning calorimetry was conducted. Raman spectrum, infrared transmission spectrum, absorption spectrum were measured. Fluorescence spectrum and lifetime of emission around 1.53 ?m were measured under 970 nm laser diode excitation. The metaphosphate content in the composition is limited, but the maximum phonon energy of glass amounts to 1290 cm-1, and is comparatively high. The full width at half maximum is about 56 nm, and is wider than for most of the materials investigated. The measured lifetime of 4 I 13/2?4 I 15/2 transition, contributed by the high phonon energy, inefficient interaction of Er3+ ions, and low water content, amounts to no less than 7.36 ms though the Er3+ concentration is high. This work might provide useful information for the development of compact optical devices.

  18. Novel inorganic nanomaterials generated with highly concentrated sunlight

    Science.gov (United States)

    Gordon, Jeffrey M.; Katz, Eugene A.; Feuermann, Daniel; Albu-Yaron, Ana; Levy, Moshe; Tenne, Reshef

    2008-08-01

    Reactors driven by highly concentrated sunlight can create conditions well suited to the synthesis of inorganic nanomaterials. We report the experimental realization of a broad range of closed-cage (fullerene-like) nanostructures, nanotubes and/or nanowires for MoS2, SiO2 and Si, achieved via solar ablation. The solar technique generates the strong temperature and radiative gradients - in addition to the extensive high-temperature annealing environment - conducive to producing such nanostructures. The identity of the nanostructures was established with TEM, HRTEM and EDS. The fullerene-like and nanotube MoS2 configurations achieved fundamentally minimum sizes predicted by molecular structural theory. Furthermore, our experiments represent the first time SiO2 nanofibers and nanospheres have been produced purely from quartz. The solar route is far less energy intensive than laser ablation and other high-temperature chemical reactors, simpler and less costly.

  19. Mitigation of houses with extremely high indoor radon concentrations

    International Nuclear Information System (INIS)

    Full text of publication follows: The paper reports on the experience of the Czech Technical University in dealing with mitigation of houses in which unusually high indoor radon concentrations were found. The whole process of remediation is illustrated by example of an old single-family house that was built in the area formed by highly permeable soils with high radon content in the soil air. T he house has a small cellar located under 1/5 of the ground floor area. Two types of floors, i.e. timber floors and cracked concrete slabs were found in the house. As a result of extremely high radon concentration in the sub-floor region (up to 600 kBq/m3) and leaky structures in contact with soil, radon concentrations around 100 kBq/m3 in the cellar and up to 60 kBq/m3 in the living rooms on the ground floor were measured prior to mitigation. Mitigation measures that were carried out in the house consist of reconstruction of timber floors and installation of active soil depressurization. Timber floors were replaced with concrete slab fitted with damp proof membrane, thermal insulation and floor covering. The soil depressurization system was made up of two sections. The first section is composed of the network of perforated pipes inserted in the drainage layer placed under the new floors and four perforated tubes drilled under the existing floors. The soil air from this section is extracted by means of a roof fan installed at the top of the vertiroof fan installed at the top of the vertical exhaust pipe running inside the living space and terminating above the roof. The second section was designed to withdraw by means of a small fan radon-laden air from the filling in the floor above the cellar and from perforated tubes drilled into the sub-floor region under the rooms adjacent to the cellar. It serves also for the active ventilation of the cellar. Pressure, temperature and radon concentration sensors were installed into the drainage layer during the reconstruction of floors to record variations in these parameters caused by soil ventilation and depressurization. Measured data were used not only for the verification of the remediation effectiveness, but also for the analysis of possible negative effects (reduced under floor temperatures, drying and freezing of the subsoil, etc.). Investigation of these effects is very important, because they can lead to additional settlement of the house resulting in appearance of micro -cracks in the house substructure. To minimize negative effects both fans operate in intermittent mode with the frequency of operating periods depending on the rate of decrease and increase of indoor radon concentration after switching on and off the fans. The effectiveness of installed measures had been verified by measurements of indoor radon concentration during various operating modes. Radon levels in all habitable rooms had been successfully reduced below the action level for existing houses 400 Bq/m3. These results indicate that even in houses with extremely high indoor radon concentrations effective reduction of indoor radon is possible supposing that only effective measures are applied and their design takes into account specific soil and house characteristics. (authors)

  20. Mapping Global Atmospheric CO2 Concentration at High Spatiotemporal Resolution

    Directory of Open Access Journals (Sweden)

    Yingying Jing

    2014-11-01

    Full Text Available Satellite measurements of the spatiotemporal distributions of atmospheric CO2 concentrations are a key component for better understanding global carbon cycle characteristics. Currently, several satellite instruments such as the Greenhouse gases Observing SATellite (GOSAT, SCanning Imaging Absorption Spectrometer for Atmospheric CHartographY (SCIAMACHY, and Orbiting Carbon Observatory-2 can be used to measure CO2 column-averaged dry air mole fractions. However, because of cloud effects, a single satellite can only provide limited CO2 data, resulting in significant uncertainty in the characterization of the spatiotemporal distribution of atmospheric CO2 concentrations. In this study, a new physical data fusion technique is proposed to combine the GOSAT and SCIAMACHY measurements. On the basis of the fused dataset, a gap-filling method developed by modeling the spatial correlation structures of CO2 concentrations is presented with the goal of generating global land CO2 distribution maps with high spatiotemporal resolution. The results show that, compared with the single satellite dataset (i.e., GOSAT or SCIAMACHY, the global spatial coverage of the fused dataset is significantly increased (reaching up to approximately 20%, and the temporal resolution is improved by two or three times. The spatial coverage and monthly variations of the generated global CO2 distributions are also investigated. Comparisons with ground-based Total Carbon Column Observing Network (TCCON measurements reveal that CO2 distributions based on the gap-filling method show good agreement with TCCON records despite some biases. These results demonstrate that the fused dataset as well as the gap-filling method are rather effective to generate global CO2 distribution with high accuracies and high spatiotemporal resolution.

  1. Comparative Investigation of Benzene Steam Reforming over Spinel Supported Rh and Ir Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Mei, Donghai; Lebarbier, Vanessa MC; Rousseau, Roger J.; Glezakou, Vassiliki Alexandra; Albrecht, Karl O.; Kovarik, Libor; Flake, Matthew D.; Dagle, Robert A.

    2013-06-01

    In a combined experimental and first-principles density functional theory (DFT) study, benzene steam reforming (BSR) over MgAl2O4 supported Rh and Ir catalysts was investigated. Experimentally, it has been found that both highly dispersed Rh and Ir clusters (1-2 nm) on the MgAl2O4 spinel support are stable during the BSR in the temperature range of 700-850?C. Compared to the Ir/MgAl2O4 catalyst, the Rh/MgAl2O4 catalyst is more active with higher benzene turnover frequency and conversion. At typical steam conditions with the steam-to-carbon ratio > 12, the benzene conversion is only a weak function of the H2O concentration in the feed. This suggests that the initial benzene decomposition step rather than the benzene adsorption is most likely the rate-determined step in BSR over supported Rh and Ir catalysts. In order to understand the differences between the two catalysts, we followed with a comparative DFT study of initial benzene decomposition pathways over two representative model systems for each supported metal (Rh and Ir) catalysts. A periodic terrace (111) surface and an amorphous 50-atom metal cluster with a diameter of 1.0 nm were used to represent the two supported model catalysts under low and high dispersion conditions. Our DFT results show that the decreasing catalyst particle size enhances the benzene decomposition on supported Rh catalysts by lowering both C-C and C-H bond scission. The activation barriers of the C-C and the C-H bond scission decrease from 1.60 and 1.61 eV on the Rh(111) surface to 1.34 and 1.26 eV on the Rh50 cluster. For supported Ir catalysts, the decreasing particle size only affects the C-C scission. The activation barrier of the C-C scission of benzene decreases from 1.60 eV on the Ir(111) surface to 1.35 eV on the Ir50 cluster while the barriers of the C-H scission are practically the same. The experimentally measured higher BSR activity on the supported highly dispersed Rh catalyst can be rationalized by the thermodynamic limitation for the very first C-C bond scission of benzene on the small Ir50 catalyst. The C-C bond scission of benzene on the small Ir50 catalyst is highly endothermic although the barrier is competitive with the barriers of both the C-C and the C-H bond-breakings on the small Rh50 catalyst. The calculations also imply that, for the supported Rh catalysts the C-C and C-H bond scissions are competitive, independently of the Rh cluster sizes. After the initial dissociation step via either the C-C or the C-H bond scission, the C-H bond breaking seems to be more favorable rather than the C-C bond breaking on the larger Rh terrace surface. This work was financially supported by the United States Department of Energy’s Office of Biomass Program’s. Computing time was granted by a user project at the Molecular Science Computing Facility in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.

  2. Particulate Matter Concentrations in East Oakland's High Street Corridor

    Science.gov (United States)

    Lei, P.; Jackson, J.; Lewis, R.; Marigny, A.; Mitchell, J. D.; Nguyen, R.; Philips, B.; Randle, D.; Romero, D.; Spears, D.; Telles, C.; Weissman, D.

    2012-12-01

    Particulate matter (PM) is a complex mixture of small solid pieces and/or liquid droplets in the air. High concentrations of PM can pose a serious health hazard because inhalation can result in breathing problems and/or aggravate asthma. Long term exposure can increase the likelihood of respiratory problems like asthma and emphysema as well as cancer. The smaller the particles, the deeper they can get into the respiratory system. For this reason, the smallest particles, those smaller than 2.5 micrometers in diameter (PM2.5), are the most dangerous. PM2.5 is largely emitted from motor vehicles burning fuels that don't break down fully. Our research team investigated the levels of PM2.5 as well as particles smaller than 10 micrometers (PM10) and total suspended particulate (TSP) along the northeast-southwest trending High Street Corridor, near Fremont High School in East Oakland, California. Using the Aerocet 531 mass particle counter, team members walked through neighborhoods and along major roads within a 1 mile radius of Fremont High School. The Aerocet 531 recorded two minute average measurements of all the relevant PM sizes, which are reported in mg/m3. Measurements were consistently taken in the morning, between 8:30 and 11:30 am. Preliminary results indicate maximum readings of all PM sizes at sites that are in close proximity to a major freeway (Interstate-880). These results support our initial hypothesis that proximity to major roads and freeways, especially those with high diesel-fuel burning truck traffic, would be the primary factor affecting PM concentration levels. Preliminary median and maximum readings all suggest particulate matter levels below what the EPA would consider unhealthy or risky.

  3. Conduction processes in high acceptor concentration HgTe

    International Nuclear Information System (INIS)

    The effects of vacancy induced acceptors in zero gap semiconductors, like in HgTe, are treated by the resonant state theory. First, one scattering center is considered, then multiple scattering is developed in the case of acceptor concentrations up to 1 x 1022 m-3. In this investigation the effects of even higher acceptor concentrations (N >= 1 x 1023 m-3) are elucidated. It is shown that in this case the resonant state model is no longer applicable since the randomly distributed impurities result in a fluctuating potential field. Thus the impurity disorder introduces an Anderson type conduction process. This is characterized by a large change in the mobility when the Fermi level goes through the acceptor band. These mobilities, related to the Anderson type conduction mechanisms, are in good agreement with the experimentally determined ones in the case of HgTe. While using the resonant state theory, the predicted mobilities are not in satisfactory agreement with the measured ones in the high acceptor concentration range analyzed in this investigation. (author)

  4. Interleukin-10 involvement in exposure to low dose of benzene.

    Science.gov (United States)

    Spatari, Giovanna; Saitta, Salvatore; Giorgianni, Concetto; Cristani, Maria Teresa; Quattrocchi, Paolina; Abbate, Adriana; Carrieri, Mariella; Ferraro, Giorgia; Saija, Antonella; Gangemi, Sebastiano

    2013-02-15

    OBJECTIVE: To establish if serum levels of interleukin-10 (IL-10) in subjects exposed to benzene are connected with age, working years, and employment age. METHODS: We evaluated serum levels of IL-10 in 51 employees working in oil refinery (group A) and in 16 office workers who resided in the same area (group B). RESULTS: There was no statistically significant difference between serum concentrations of IL-10 in groups A and B. There was a statistically significant dependent relationship in group A between age, working years, and serum concentration of IL-10. There was a statistically significant and positive dependent relationship in group A between serum concentration of IL-10 and employment age. CONCLUSIONS: The role played by IL-10 in benzene immune suppression may be relevant and attention should be directed toward assessment of age, working years, and employment age in benzene-exposed populations. PMID:23344822

  5. Hydrogen concentration and distribution in high-purity germanium crystals

    International Nuclear Information System (INIS)

    High-purity germanium crystals used for making nuclear radiation detectors are usually grown in a hydrogen ambient from a melt contained in a high-purity silica crucible. The benefits and problems encountered in using a hydrogen ambient are reviewed. A hydrogen concentration of about 2 x 1015cm-3 has been determined by growing crystals in hydrogen spiked with tritium and counting the tritium ?-decays in detectors made from these crystals. Annealing studies show that the hydrogen is strongly bound, either to defects or as H2 with a dissociation energy > 3 eV. This is lowered to 1.8 eV when copper is present. Etching defects in dislocation-free crystals grown in hydrogen have been found by etch stripping to have a density of about 1 x 107 cm-3 and are estimated to contain 108 H atoms each

  6. Shock initiation studies on high concentration hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Sheffield, Stephen A [Los Alamos National Laboratory; Dattelbaum, Dana M [Los Alamos National Laboratory; Stahl, David B [Los Alamos National Laboratory; Gibson, L. Lee [Los Alamos National Laboratory; Bartram, Brian D. [Los Alamos National Laboratory

    2009-01-01

    Concentrated hydrogen peroxide (H{sub 2}O{sub 2}) has been known to detonate for many years. However, because of its reactivity and the difficulty in handling and confining it, along with the large critical diameter, few studies providing basic information about the initiation and detonation properties have been published. We are conducting a study to understand and quantify the initiation and detonation properties of highly concentrated H{sub 2}O{sub 2} using a gas-driven two-stage gun to produce well defined shock inputs. Multiple magnetic gauges are used to make in-situ measurements of the growth of reaction and subsequent detonation in the liquid. These experiments are designed to be one-dimensional to eliminate any difficulties that might be encountered with large critical diameters. Because of the concern of the reactivity of the H{sub 2}O{sub 2} with the confining materials, a remote loading system has been developed. The gun is pressurized, then the cell is filled and the experiment shot within less than three minutes. TV cameras are attached to the target so the cell filling can be monitored. Several experiments have been completed on {approx}98 wt % H{sub 2}O{sub 2}/H{sub 2}O mixtures; initiation has been observed in some experiments that shows homogeneous shock initiation behavior. The initial shock pressurizes and heats the mixture. After an induction time, a thermal explosion type reaction produces an evolving reactive wave that strengthens and eventually overdrives the first wave producing a detonation. From these measurements, we have determined unreacted Hugoniot information, times (distances) to detonation (Pop-plot points) that indicate low sensitivity, and detonation velocities of high concentration H{sub 2}O{sub 2}/H{sub 2}O solutions that agree with earlier estimates.

  7. Collision lifetimes of polyatomic molecules at low temperatures: Benzene-benzene vs benzene-rare gas atom collisions

    Science.gov (United States)

    Cui, Jie; Li, Zhiying; Krems, Roman V.

    2014-10-01

    We use classical trajectory calculations to study the effects of the interaction strength and the geometry of rigid polyatomic molecules on the formation of long-lived collision complexes at low collision energies. We first compare the results of the calculations for collisions of benzene molecules with rare gas atoms He, Ne, Ar, Kr, and Xe. The comparison illustrates that the mean lifetimes of the collision complexes increase monotonically with the strength of the atom-molecule interaction. We then compare the results of the atom-benzene calculations with those for benzene-benzene collisions. The comparison illustrates that the mean lifetimes of the benzene-benzene collision complexes are significantly reduced due to non-ergodic effects prohibiting the molecules from sampling the entire configuration space. We find that the thermally averaged lifetimes of the benzene-benzene collisions are much shorter than those for Xe with benzene and similar to those for Ne with benzene.

  8. Collision lifetimes of polyatomic molecules at low temperatures: Benzene–benzene vs benzene–rare gas atom collisions

    International Nuclear Information System (INIS)

    We use classical trajectory calculations to study the effects of the interaction strength and the geometry of rigid polyatomic molecules on the formation of long-lived collision complexes at low collision energies. We first compare the results of the calculations for collisions of benzene molecules with rare gas atoms He, Ne, Ar, Kr, and Xe. The comparison illustrates that the mean lifetimes of the collision complexes increase monotonically with the strength of the atom–molecule interaction. We then compare the results of the atom–benzene calculations with those for benzene–benzene collisions. The comparison illustrates that the mean lifetimes of the benzene–benzene collision complexes are significantly reduced due to non-ergodic effects prohibiting the molecules from sampling the entire configuration space. We find that the thermally averaged lifetimes of the benzene–benzene collisions are much shorter than those for Xe with benzene and similar to those for Ne with benzene

  9. Collision lifetimes of polyatomic molecules at low temperatures: Benzene–benzene vs benzene–rare gas atom collisions

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Jie; Krems, Roman V. [Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1 (Canada); Li, Zhiying [Department of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States)

    2014-10-28

    We use classical trajectory calculations to study the effects of the interaction strength and the geometry of rigid polyatomic molecules on the formation of long-lived collision complexes at low collision energies. We first compare the results of the calculations for collisions of benzene molecules with rare gas atoms He, Ne, Ar, Kr, and Xe. The comparison illustrates that the mean lifetimes of the collision complexes increase monotonically with the strength of the atom–molecule interaction. We then compare the results of the atom–benzene calculations with those for benzene–benzene collisions. The comparison illustrates that the mean lifetimes of the benzene–benzene collision complexes are significantly reduced due to non-ergodic effects prohibiting the molecules from sampling the entire configuration space. We find that the thermally averaged lifetimes of the benzene–benzene collisions are much shorter than those for Xe with benzene and similar to those for Ne with benzene.

  10. Phenylguanine found in urine after benzene exposure.

    OpenAIRE

    Norpoth, K. H.; Mu?ller, G.; Schell, C.; Jorg, E.

    1996-01-01

    Comparative investigations with synthetic N7-phenylguanine were carried out to clarify whether this compound is eliminated via the urine of rats as a benzene-derived nucleic acid adduct. As sensitive methods for detecting trace amounts of the compound, gas chromatography-mass spectroscopy, high performance liquid chromatography, and two immunoassays (enzyme-linked immunosorbent assay and fluoroimmunoassay) with appropriate monoclonal antibodies were used. The results indicate the excretion of...

  11. Source identification of high glyme concentrations in the Oder River.

    Science.gov (United States)

    Stepien, D K; Püttmann, W

    2014-05-01

    The objective of the following study was to identify the source of high concentrations of glycol diethers (diglyme, triglyme, and tetraglyme) in the Oder River. Altogether four sampling campaigns were conducted and over 50 surface samples collected. During the first two samplings of the Oder River in the Oderbruch region (km 626-690), glymes were detected at concentrations reaching 0.065 ?g L(-1) (diglyme), 0.54 ?g L(-1) (triglyme) and 1.7 ?g L(-1) (tetraglyme). The subsequent sampling of the Oder River, from the area close to the source to the Poland-Germany border (about 500 km) helped to identify the possible area of the dominating glyme entry into the river between km 310 and km 331. During that sampling, the maximum concentration of triglyme was 0.46 ?g L(-1) and tetraglyme 2.2 ?g L(-1); diglyme was not detected. The final sampling focused on the previously identified area of glyme entry, as well as on tributaries of the Oder River. Samples from Czarna Woda stream and Kaczawa River contained even higher concentrations of diglyme, triglyme, and tetraglyme, reaching 5.2 ?g L(-1), 13 ?g L(-1) and 81 ?g L(-1), respectively. Finally, three water samples were analyzed from a wastewater treatment plant receiving influents from a Copper Smelter and Refinery; diglyme, triglyme, and tetraglyme were present at a maximum concentration of 1700 ?g L(-1), 13,000 ?g L(-1), and 190,000 ?g L(-1), respectively. Further research helped to identify the source of glymes in the wastewater. The gas desulfurization process Solinox uses a mixture of glymes (Genosorb(®)1900) as a physical absorption medium to remove sulfur dioxide from off-gases from the power plant. The wastewater generated from the process and from the maintenance of the equipment is initially directed to the wastewater treatment plant where it undergoes mechanical and chemical treatment processes before being discharged to the tributaries of the Oder River. Although monoglyme was also analyzed, it was not detected in any of the water samples. PMID:24583522

  12. Anomalous high ozone concentrations recorded at a high mountain station in Italy in summer 2003

    Science.gov (United States)

    Cristofanelli, P.; Bonasoni, P.; Carboni, G.; Calzolari, F.; Casarola, L.; Zauli Sajani, S.; Santaguida, R.

    In order to evaluate the possible effects of heatwave phenomena on background O 3 concentrations, the average summer O 3 concentrations at the high mountain station of Mt. Cimone (MTC—2165 m a.s.l.) have been analyzed. In particular, at this baseline station unusually high O 3 concentrations were recorded during August 2003, when an intense heatwave (the "August heatwave") affected Europe. During this heatwave, the highest O 3 concentrations were recorded at MTC in connection with air masses coming from continental Europe and the Po basin boundary layer as shown by three-dimensional air mass back-trajectory and mixing height analyzes. However, high O 3 concentrations were also recorded in air masses coming from the middle troposphere (above 3000 m a.s.l.), thus suggesting the presence of O 3-rich atmospheric layers over Europe. This could be due to the large extension of the mixing layer which favoured the transport of high concentrations of O 3 and its precursors to altitudes that would usually be in the free troposphere. Other than from traffic and industrial activities, a contribution to the high O 3 concentrations recorded at MTC during the August heatwave could derive from fires in the North of Italy, as suggested by a well-documented episode and supported by in situ CO 2 measurements used as non-conventional tracer for fire emissions.

  13. High-efficiency solidification of PWR concentrate wastes

    International Nuclear Information System (INIS)

    A high-efficiency process for the solidification of liquid borate waste generated in nuclear power plants has been successfully developed at the Institute of Nuclear Energy Research (INER). In this process, liquid borate wastes were concentrated to have a boron content more than 100,000 ppm and then blended with an elaborately formulated solidification agent to form a hardenable slurry. The slurry is highly flowable initially and then hardened within 30 minutes forming a solidified product of high strength. Experimental results indicated that the solidification may be resulted from the condensation reaction of polyborate and the solidification agent. Characterization of the solidified product showed that the waste form quality including compressive strength, water immersion resistance, irradiation resistance, leaching resistance and thermal cycling resistance is superior to the acceptance criteria of the USNRC regulation. Also the volume efficiency of the process is more than 5 times of the conventional cementation process. Simplicity is another feature of the process; operating procedure and equipment are almost the same as cementation. To use the process will bring a tremendous benefit because of the low capital investment and high volume efficiency. A system for the solidification of liquid borate waste in 55-gal drums was built in INER; test running of the system showed a satisfactory result. Characteristics of the process, quality of waste forms and performance o, quality of waste forms and performance of the full-scale solidification test will be revealed in this report. (author)

  14. Characterization of blood donors with high haemoglobin concentration

    DEFF Research Database (Denmark)

    Magnussen, K; Hasselbalch, H C

    2013-01-01

    Background and Objectives? The literature contains little on the prevalence and causes of high predonation haemoglobin levels among blood donors. This study aimed to characterize and develop an algorithm to manage would-be donors with polycythaemia. Materials and Methods? Between November 2009 and November 2011, we offered haematology consultations to blood donors with repeated haemoglobin concentration (Hb) above the WHO limit for polycythaemia vera (PV) (10·2 and 11·5?mm/16·5 and 18·5?g/dl for women and men, respectively). Investigation of such donors included Hb, haematocrit, mean cell volume, erythropoietin, ferritin, platelet count and leucocyte count, JAK2?V617 and JAK2 exon12 analysis, as well as other routine measurements. Results? Among 46 such donors, 39 had a history of smoking, which contributes to erythrocytosis. Two had PV, five had severe hypertension, one of them because of renal artery stenosis, and two had diabetes mellitus. Thus, we found a high morbidity among such donors. Of the 36 others, 30 donated again before May 2012, at which time the Hb was significantly lower. Conclusion? We recommend JAK2?V617 and JAK2 exon12 screening and clinical investigation for donors with concurrently high Hb, high haematocrit and iron deficiency. We also recommend that they stop or cut down on smoking to reduce the risk of thrombosis in general. We disqualified 10 of the donors.

  15. Benzene-derived carbon nanothreads

    Science.gov (United States)

    Fitzgibbons, Thomas C.; Guthrie, Malcolm; Xu, En-Shi; Crespi, Vincent H.; Davidowski, Stephen K.; Cody, George D.; Alem, Nasim; Badding, John V.

    2015-01-01

    Low-dimensional carbon nanomaterials such as fullerenes, nanotubes, graphene and diamondoids have extraordinary physical and chemical properties. Compression-induced polymerization of aromatic molecules could provide a viable synthetic route to ordered carbon nanomaterials, but despite almost a century of study this approach has produced only amorphous products. Here we report recovery to ambient pressure of macroscopic quantities of a crystalline one- dimensional sp3 carbon nanomaterial formed by high-pressure solid-state reaction of benzene. X-ray and neutron diffraction, Raman spectroscopy, solid-state NMR, transmission electron microscopy and first-principles calculations reveal close- packed bundles of subnanometre-diameter sp3-bonded carbon threads capped with hydrogen, crystalline in two dimensions and short-range ordered in the third. These nanothreads promise extraordinary properties such as strength and stiffness higher than that of sp2 carbon nanotubes or conven tional high-strength polymers. They may be the first member of a new class of ordered sp3 nanomaterials synthesized by kinetic control of high-pressure solid-state reactions.

  16. Acetate biodegradation by anaerobic microorganisms at high pH and high calcium concentration

    International Nuclear Information System (INIS)

    Acetate biodegradation at a high pH and a high calcium concentration was examined to clarify the effect of bacterial activity on the migration of organic 14C compounds in cementitious repositories. Tamagawa river sediment or Teganuma pond sediment was anaerobically cultured with 5 mM acetate and 10 mM nitrate at pH 9.5-12 at 30 oC. After 20 and 90 days, the acetate concentration of the culture medium was analyzed and found to have decreased below 5 mM at pH ? 11. On the other hand, it did not decrease when either sediment was incubated in the absence of nitrate. These results suggest that nitrate-reducing bacteria can biodegrade acetate under more alkaline conditions than the reported pH range in which nitrate-reducing bacteria can exhibit activity. Acetate biodegradation was also examined at a high calcium concentration. Sediments were anaerobically cultured at pH 9.5 with 5 mM acetate and 10 mM nitrate in solution, equilibrated with ordinary Portland cement hydrate, in which the Ca concentration was 14.6 mM. No decrease in acetate concentration after incubation of the sediments was observed, nor was it lower than in the absence of cementitious composition, suggesting that kinetics of acetate biodegradation by anaerobic microorganisms is lowered by a high Ca concentration. - Research highlights: ? Acetate biodegradation at a high pH and a high calcium concentration was examined to clarify the effect of bacterial activity on the migration of acterial activity on the migration of organic 14C compounds in cementitious repositories. ? Nitrate-reducing bacteria can biodegrade acetate at pH ? 11. ? Kinetics of acetate biodegradation by anaerobic microorganisms might be lowered by a high Ca concentration.

  17. Reactions of energetic carbon-11 with benzene leading to acetylene

    International Nuclear Information System (INIS)

    The reactions of energetic carbon-11 leading to acetylene were studied in specifically deuteriated benzene and 50/50 mixtures of perdeuteriated and perprotonated benzenes and alkanes. The contributions of intermolecular and intramolecular mechanisms in acetylene formation in benzene were deduced from the relative yields of the three isotopic acetylenes /sup (11)/C2H2, /sup (11)/C2HD, and /sup (11)/C2D2. High-energy stripping and abstraction reactions of /sup (11)/C2 and /sup (11)/C2H ions appear to account for acetylene formed via an intermolecular pathway. After correction for the intermolecular mechanisms, the remaining acetylene is formed mainly by direct insertion (? or ?) plus a small contribution from a mechanism involving random selection of H or D in the benzene molecule

  18. Gene expression profile in bone marrow and hematopoietic stem cells in mice exposed to inhaled benzene

    Energy Technology Data Exchange (ETDEWEB)

    Faiola, Brenda; Fuller, Elizabeth S.; Wong, Victoria A.; Recio, Leslie

    2004-05-18

    Acute myeloid leukemia and chronic lymphocytic leukemia are associated with benzene exposure. In mice, benzene induces chromosomal breaks as a primary mode of genotoxicity in the bone marrow (BM). Benzene-induced DNA lesions can lead to changes in hematopoietic stem cells (HSC) that give rise to leukemic clones. To gain insight into the mechanism of benzene-induced leukemia, we investigated the DNA damage repair and response pathways in total bone marrow and bone marrow fractions enriched for HSC from male 129/SvJ mice exposed to benzene by inhalation. Mice exposed to 100 ppm benzene for 6 h per day, 5 days per week for 2 week showed significant hematotoxicity and genotoxicity compared to air-exposed control mice. Benzene exposure did not alter the level of apoptosis in BM or the percentage of HSC in BM. RNA isolated from total BM cells and the enriched HSC fractions from benzene-exposed and air-exposed mice was used for microarray analysis and quantitative real-time RT-PCR. Interestingly, mRNA levels of DNA repair genes representing distinct repair pathways were largely unaffected by benzene exposure, whereas altered mRNA expression of various apoptosis, cell cycle, and growth control genes was observed in samples from benzene-exposed mice. Differences in gene expression profiles were observed between total BM and HSC. Notably, p21 mRNA was highly induced in BM but was not altered in HSC following benzene exposure. The gene expression pattern suggests that HSC isolated immediately following a 2 weeks exposure to 100 ppm benzene were not actively proliferating. Understanding the toxicogenomic profile of the specific target cell population involved in the development of benzene-associated diseases may lead to a better understanding of the mechanism of benzene-induced leukemia and may identify important interindividual and tissue susceptibility factors.

  19. Coagulation pretreatment of highly concentrated acrylonitrile wastewater from petrochemical plants.

    Science.gov (United States)

    Zheng, Dongju; Qin, Lin; Wang, Tao; Ren, Xiaojing; Zhang, Zhongguo; Li, Jiding

    2014-01-01

    Acrylonitrile (AN) wastewater is a heavily polluted and a likely hazardous liquid that is generated during the production of AN. Several chemical methods for the pretreatment of AN wastewater are available in laboratory scale. However, the harsh reaction conditions and high operational cost make these methods undesirable. Until now, four-effect evaporation is the only pretreatment method used for AN wastewater in industry despite its huge energy consumption and high cost. It is difficult to find an energy-saving pretreatment technique from the perspective of industrial application. In this study, a safe and low-cost coagulation technique was developed for the pretreatment of AN wastewater. Three types of inorganic coagulant and three types of polymer coagulant were investigated for the coagulation treatment of highly concentrated AN wastewater from petrochemical plants. The effects of coagulant type, dosage, and coagulation conditions on the pretreatment efficiency of AN wastewater were investigated. The results show that a combination of inorganic and polymer coagulants is effective for the pretreatment of AN wastewater. PMID:25051483

  20. YAG nano-light sources with high Ce concentration

    CERN Document Server

    Masenelli, Bruno; Boisron, Olivier; Canut, Bruno; Ledoux, Gilles; Bluet, Jean-Marie; Melinon, Patrice; Huant, Serge

    2013-01-01

    We investigate the luminescence properties of 10 nm YAG nanoparticles doped with Ce ions at 0.2%, 4% and 13% that are designed as active probes for Scanning Near field Optical Microscopy. They are produced by a physical method without any subsequent treatment, which is imposed by the desired application. The structural analysis reveals the amorphous nature of the particles, which we relate to some compositional defect as indicated by the elemental analysis. The optimum emission is obtained with a doping level of 4%. The emission of the YAG nanoparticles doped at 0.2% is strongly perturbed by the crystalline disorder whereas the 13% doped particles hardly exhibit any luminescence. In the latter case, the presence of Ce4+ ions is confirmed, indicating that the Ce concentration is too high to be incorporated efficiently in YAG nanoparticles in the trivalent state. By a unique procedure combining cathodoluminescence and Rutherford backscattering spectrometry, we demonstrate that the enhancement of the particles l...

  1. Remote sensing of chlorophyll concentration from high altitude

    Science.gov (United States)

    Leung, K. C.; Hovis, W. A.

    1976-01-01

    A series of remote sensing experiments, using an airborne Ocean Color Scanner (OCS), has been carried out to demonstrate the feasibility of detecting surface chlorophyll concentrations in coastal water from high altitude. Upwelling radiance from the sea surface was recorded by 10 narrow bandwidth wavelength channels of the OCS, at an altitude of 19.8 km. Measurements were made over areas with vastly different biological activities. A strong correlation between the OCS radiance measurements and the surface chlorophyll measurements was found. The extracted chlorophyll signature agreed qualitatively with results from low altitude observations, except in the blue region. In addition, it was found that a simple algorithm could be used to estimate reliable chlorophyll distributions from OCS measurements.

  2. High concentration of gadolinium ion modifying isolated rice mitochondrial biogenesis.

    Science.gov (United States)

    Zhao, Jie; Jin, Jian-Cheng; Zhou, Zhi-Qiang; Xia, Cai-Fen; Yang, Xiao-Gang; Jiang, Feng-Lei; Dai, Jie; Liu, Yi

    2013-12-01

    Mitochondria play an important role in plant growth and development, cooperating with the endoplasmic reticulum and nucleus. Gadolinium, one of the rare earth elements, is an inhibitor of stretch-activated calcium channels located on the endoplasmic reticulum and plasma membrane and has no effect on nuclear calcium variation in plant cells. We analyzed the effects of Gd3+ on mitochondria function by monitoring mitochondrial swelling, changes of membrane fluidity, and transmembrane potential collapse and by observing mitochondrial ultrastructure. We found that high concentration of Gd3+ induces rice mitochondrial dysfunction through mitochondrial permeability transition (MPT). The protection of DTT and EDTA demonstrate that Gd3+ blocks the inner membrane ion channel through thiol chelation. PMID:24078325

  3. Substituent effect in benzene dication

    OpenAIRE

    Palusiak, Marcin; Domaga?a, Ma?gorzata; Dominikowska, Justyna; Bickelhaupt, F. Matthias

    2014-01-01

    2 Abstract It was r ecently postulated that the benzene ring and its 4n+2 ? - electron analogues are resistant to the substituent effect due to the fact that such systems tend to keep its delocalized character. Therefore, the 4n ? - electron dicationic form of benzene should appear to be less resistant to the substituent effect, as compar ed with its parent neutral molecule. For this reason the effect of substi...

  4. Law and regulation of benzene.

    OpenAIRE

    Feitshans, I. L.

    1989-01-01

    OSHA has created final benzene regulations after extensive rulemakings on two occasions, 1978 and 1987. These standards have been the subject of extensive litigation for nearly 20 years. This article examines in detail the conceptual underpinnings of the Benzene Case, (which was decided by the U.S. Supreme Court in 1980) in light of U.S. administrative law precedents that have set limits upon administrative discretion under the test for "substantial evidence" and the "hard look doctrine." Thi...

  5. Major sources of benzene exposure.

    OpenAIRE

    Wallace, L. A.

    1989-01-01

    Data from EPA's TEAM Study allow us to identify the major sources of exposure to benzene for much of the U.S. population. These sources turn out to be quite different from what had previously been considered the important sources. The most important source of exposure for 50 million smokers is the mainstream smoke from their cigarettes, which accounts for about half of the total population burden of exposure to benzene. Another 20% of nationwide exposure is contributed by various personal act...

  6. Highly Concentrated Acetic Acid Poisoning: 400 Cases Reviewed

    Directory of Open Access Journals (Sweden)

    Konstantin Brusin

    2012-12-01

    Full Text Available Background: Caustic substance ingestion is known for causing a wide array of gastrointestinal and systemic complications. In Russia, ingestion of acetic acid is a major problem which annually affects 11.2 per 100,000 individuals. The objective of this study was to report and analyze main complications and outcomes of patients with 70% concentrated acetic acid poisoning. Methods: This was a retrospective study of patients with acetic acid ingestion who were treated at Sverdlovsk Regional Poisoning Treatment Center during 2006 to 2012. GI mucosal injury of each patient was assessed with endoscopy according to Zargar’s scale. Data analysis was performed to analyze the predictors of stricture formation and mortality. Results: A total of 400 patients with median age of 47 yr were included. GI injury grade I was found in 66 cases (16.5%, IIa in 117 (29.3%, IIb in 120 (30%, IIIa in 27 (16.7% and IIIb in 70 (17.5%. 11% of patients developed strictures and overall mortality rate was 21%. Main complications were hemolysis (55%, renal injury (35%, pneumonia (27% and bleeding during the first 3 days (27%. Predictors of mortality were age 60 to 79 years, grade IIIa and IIIb of GI injury, pneumonia, stages “I”, “F” and “L” of kidney damage according to the RIFLE scale and administration of prednisolone. Predictors of stricture formation were ingestion of over 100 mL of acetic acid and grade IIb and IIIa of GI injury. Conclusion: Highly concentrated acetic acid is still frequently ingested in Russia with a high mortality rate. Patients with higher grades of GI injury, pneumonia, renal injury and higher amount of acid ingested should be more carefully monitored as they are more susceptible to develop fatal consequences.          

  7. Effects of Benzene on human hematopoiesis

    OpenAIRE

    Kirkeleit, Jorunn; Riise, Trond; Gjertsen, Bjørn Tore; Moen, Bente E.; Bra?tveit, Magne; Bruserud, Øystein

    2008-01-01

    Benzene, an aromatic hydrocarbon that is a natural component of crude oil and natural gas, is toxic to the blood and blood-forming organs. Epidemiological studies have established an association between benzene exposure and acute myeloid leukemia, and increasing evidence also indicates a possible association between benzene and multiple myeloma. A specific benzene-associated myelodysplastic syndrome has also been suggested. Chronic hematotoxic effects of benzene exposure, includin...

  8. Optimized UV Detection of High-Concentration Antibody Formulations using High-Throughput SE-HPLC.

    Science.gov (United States)

    Molloy, Shabnam; Fesinmeyer, R Mathew; Martinez, Theresa; Murphy, Piedmonte D; Pelletier, Mary E; Treuheit, Michael J; Kleemann, Gerd R

    2015-02-01

    High-concentration antibody solutions (>100 mg/mL) present significant challenges for formulation and process development, including formulation attributes such as increased solution viscosity, and the propensity for self-association. An additional challenge comes from the adaptation of analytical methods designed for low-concentration formulations to the high-concentration regime. The oligomeric state is a good example: it is a quality attribute monitored during pharmaceutical development and is one that can be affected by dilution; a typical first step in the analysis of high-concentration solutions. The objective of this work was to develop a size-exclusion HPLC (SE-HPLC) method that would allow the injection of high-concentration antibody formulations without the need for dilution prior to injection and their analysis in a high-throughput manner that does not create a bottleneck for the execution of complex formulation development studies. It was found that changing the UV detection wavelength from 215 to 235 nm simplified sample preparation by allowing for an approximately fivefold increase in injection load while maintaining the signal within the linear range of detection. In addition, the chromatographic peak properties (i.e., peak symmetry, resolution, and sensitivity) were determined to be consistent when compared with analytical methods developed for formulations with lower antibody concentrations. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:508-514, 2015. PMID:25392911

  9. Microbial life at high salt concentrations: phylogenetic and metabolic diversity

    Directory of Open Access Journals (Sweden)

    Oren Aharon

    2008-04-01

    Full Text Available Abstract Halophiles are found in all three domains of life. Within the Bacteria we know halophiles within the phyla Cyanobacteria, Proteobacteria, Firmicutes, Actinobacteria, Spirochaetes, and Bacteroidetes. Within the Archaea the most salt-requiring microorganisms are found in the class Halobacteria. Halobacterium and most of its relatives require over 100–150 g/l salt for growth and structural stability. Also within the order Methanococci we encounter halophilic species. Halophiles and non-halophilic relatives are often found together in the phylogenetic tree, and many genera, families and orders have representatives with greatly different salt requirement and tolerance. A few phylogenetically coherent groups consist of halophiles only: the order Halobacteriales, family Halobacteriaceae (Euryarchaeota and the anaerobic fermentative bacteria of the order Halanaerobiales (Firmicutes. The family Halomonadaceae (Gammaproteobacteria almost exclusively contains halophiles. Halophilic microorganisms use two strategies to balance their cytoplasm osmotically with their medium. The first involves accumulation of molar concentrations of KCl. This strategy requires adaptation of the intracellular enzymatic machinery, as proteins should maintain their proper conformation and activity at near-saturating salt concentrations. The proteome of such organisms is highly acidic, and most proteins denature when suspended in low salt. Such microorganisms generally cannot survive in low salt media. The second strategy is to exclude salt from the cytoplasm and to synthesize and/or accumulate organic 'compatible' solutes that do not interfere with enzymatic activity. Few adaptations of the cells' proteome are needed, and organisms using the 'organic-solutes-in strategy' often adapt to a surprisingly broad salt concentration range. Most halophilic Bacteria, but also the halophilic methanogenic Archaea use such organic solutes. A variety of such solutes are known, including glycine betaine, ectoine and other amino acid derivatives, sugars and sugar alcohols. The 'high-salt-in strategy' is not limited to the Halobacteriaceae. The Halanaerobiales (Firmicutes also accumulate salt rather than organic solutes. A third, phylogenetically unrelated organism accumulates KCl: the red extremely halophilic Salinibacter (Bacteroidetes, recently isolated from saltern crystallizer brines. Analysis of its genome showed many points of resemblance with the Halobacteriaceae, probably resulting from extensive horizontal gene transfer. The case of Salinibacter shows that more unusual types of halophiles may be waiting to be discovered.

  10. Concentration of uranium in soils near a high mineralisation zone in a high rainfall area

    International Nuclear Information System (INIS)

    The study has been carried out near a proposed uranium mining site situated in a high rainfall area (12000 mm) in India. Soil samples were collected in two quarters from nine locations near the high mineralization zone and the concentration of U was studied. Results reflects higher value of enrichment factor in soil compared to the acidic type parent sandstone rock. High enrichment factor at locations namely Phudkylleng, Nonbahjinrin and Phudsyngkai indicates the weathering impact of altered rock containing high uranium content. (author)

  11. UV Fourier transform measurements of tropospheric O3, NO2, SO2, benzene, and toluene

    International Nuclear Information System (INIS)

    Using the differential optical absorption spectroscopy (DOAS) technique and a Fourier transform spectrometer, NO2, SO2, O3, benzene, and toluene were measured during three measurement campaigns held in Brussels in 1995, 1996, and 1997. The O3 concentrations could be explained as the results of the local photochemistry and the dynamical properties of the mixing layer. NO2 concentrations were anti-correlated to the O3 concentrations, is expected. SO2 also showed a pronounced dependence on car traffic. Average benzene and toluene concentrations were, respectively 1.7 ppb and between 4.4 and 6.6 pbb, but high values of toluene up to 98.8 ppb were observed. SO2 concentrations and to a lesser extent, those of NO2 and O3, were dependent on the wind direction. Ozone in Brussels has been found to be influenced by the meteorological conditions prevailing in central Europe. Comparisons with other measurements have shown that O3 and SO2 data are in general in good agreement, but our NO2 concentrations seem to be generally higher. (author)

  12. Modelling acceptance of sunlight in high and low photovoltaic concentration

    International Nuclear Information System (INIS)

    A simple model incorporating linear radiation characteristics, along with the optical trains and geometrical concentration ratios of solar concentrators is presented with performance examples for optical trains of HCPV, LCPV and benchmark flat-plate PV

  13. Modelling acceptance of sunlight in high and low photovoltaic concentration

    Energy Technology Data Exchange (ETDEWEB)

    Leutz, Ralf, E-mail: ralf.leutz@leopil.com [Leutz Optics and Illumination UG (haftungsbeschränkt), Marburg (Germany)

    2014-09-26

    A simple model incorporating linear radiation characteristics, along with the optical trains and geometrical concentration ratios of solar concentrators is presented with performance examples for optical trains of HCPV, LCPV and benchmark flat-plate PV.

  14. High urinary phthalate concentration associated with delayed pubarche in girls

    DEFF Research Database (Denmark)

    Frederiksen, H; SØrensen, K

    2012-01-01

    Phthalates are a group of chemicals present in numerous consumer products. They have anti-androgenic properties in experimental studies and are suspected to be involved in human male reproductive health problems. A few studies have shown associations between phthalate exposure and changes in pubertal timing among girls, although controversies exist. We determined the concentration of 12 phthalate metabolites in first morning urine samples from 725 healthy Danish girls (aged 5.6-19.1 years) in relation to age, pubertal development (breast and pubic hair stage) and reproductive hormone levels (luteinizing hormone, oestradiol and testosterone). Furthermore, urinary phthalates were determined in 25 girls with precocious puberty (PP). In general, the youngest girls with less advanced pubertal development had the highest first morning urinary concentration of the monobutyl phthalate isoforms (¿MBP((i+n)) ), monobenzyl phthalate (MBzP), metabolites of di-(2-ethylhexyl) phthalate (¿DEHPm) and of di-iso-nonyl phthalate (¿DINPm). After stratification of the urinary phthalate excretion into quartiles, we found that the age at pubarche was increasing with increasing phthalate metabolite quartiles (except for MEP). This trend was statistically significant when all phthalate metabolites (except MEP) were summarized and expressed as quartiles. No association between phthalates and breast development was observed. In addition, there were no differences in urinary phthalate metabolite levels between girls with PP and controls. We demonstrated that delayed pubarche, but not thelarche, was associated with high phthalate excretion in urine samples from 725 healthy school girls, which may suggest anti-androgenic actions of phthalates in our study group of girls.

  15. Excess volumes in the solutions benzene-H6/benzene-D6, cyclohexane-H12/benzene-H6, cyclohexane-H12/benzene-D6, and benzene-H6/benzene-D6/H2O

    International Nuclear Information System (INIS)

    Excess volumes are reported for the title solutions across the entire concentration range at 25 and 400C. For the solution of isotopic isomers, C6H6/C6D6, the excess volume shows a complicated concentration dependence with a minimum of about -6 X 10-9 m3/mol near X/sub C6H6/ = 0.33 and a maximum of about 2 X 10-9 m3/mol near X/sub C6H6/ = 0.8 (250C). The effect is sensitive to trace water content. For benzene/cyclohexane solutions the volumetric isotope effects display simpler concentration dependences. Thus, the difference, V/sup E//sub C6H6///sub C6H12/ - V/sup E//sub C6D6///sub C6H12/, within experimental error shows simple minima at X/sub benzene/ = 0.5 of about -7 X 10-9 (250C) and -12 X 10-9 (450C) m3/mol. After comparing the present results for C6H6/C6H12 solutions with those of previous workers, we discuss isotope effects in terms of the theory of isotope effects on the properties of condensed phases

  16. Airborne determination of the temporo-spatial distribution of benzene, toluene, nitrogen oxides and ozone in the boundary layer across Greater London, UK

    Science.gov (United States)

    Shaw, M. D.; Lee, J. D.; Davison, B.; Vaughan, A.; Purvis, R. M.; Lewis, A. C.; Hewitt, C. N.

    2014-10-01

    Highly spatially resolved mixing ratios of benzene and toluene, nitrogen oxides (NOx) and ozone (O3) were measured in the atmospheric boundary layer above Greater London during the period 24 June to 9 July 2013 using a Dornier 228 aircraft. Toluene and benzene were determined in-situ using a proton transfer reaction mass spectrometer (PTR-MS), NOx by dual channel NOx chemiluminescence and O3 mixing ratios by UV absorption. Average mixing ratios observed over inner London at 360 ± 10 m a.g.l. were 0.20 ± 0.05, 0.28 ± 0.07, 13.2 ± 8.6, 21.0 ± 7.3 and 34.3 ± 15.2 ppbv for benzene, toluene, NO, NO2 and NOx respectively. Linear regression analysis between NO2, benzene and toluene mixing ratios yielded a trimodal distribution indicating that these compounds predominantly share the same or co-located sources within the city and that a significant fraction of NOx is directly emitted as NO2. Average mixing ratios measured at 360 ± 10 m a.g.l. over outer London were always lower than over inner London. Where traffic densities were highest, the toluene / benzene (T / B) concentration ratios were highest (average of 1.8 ± 0.3 ppbv ppbv-1) indicative of strong local sources. Daytime maxima in NOx, benzene and toluene mixing ratios were observed in the morning (~40 ppbv NOx, ~350 pptv toluene and ~200 pptv benzene) and for ozone in the mid-afternoon (~40 ppbv O3) all at 360 ± 10 m a.g.l.

  17. Uptake, distribution, and depuration of 14C-benzene in northern anchovy, Engraulis mordax, and striped bass, Morone saxatilis

    International Nuclear Information System (INIS)

    The uptake, distribution, and depuration of water-soluble, monocyclic hydrocarbon contained in petroleum and refined products was studied in two species of marine fish. Mature northern anchovy, Engraulis mordax, and juvenile striped bass, Morone saxatilis, were exposed to sublethal concentrations of O14-benzene for 48 h. Residues in tissues exhibiting a high lipid content or representing apparent major metabolic sites were measured during the exposure and afterwards when the fish were transferred to clean seawater. Fish exhibited a rapid uptake over a wide range of benzene concentrations in the water column. Accumulation in anchovy was considerably greater than in striped bass. Results indicate that the pathway of hydrocarbons through the liver, gallbladder, intestines, and colon is a major depuration route. Residues were depurated rapidly after cessation of exposure; in striped bass tissues most residues were undetectable by 7 days

  18. A comparison of benzene, toluene and C 2-benzenes mixing ratios in automotive exhaust and in the suburban atmosphere during the introduction of catalytic converter technology to the Swiss Car Fleet

    Science.gov (United States)

    Heeb, Norbert V.; Forss, Anna-Maria; Bach, Christian; Reimann, Stefan; Herzog, Alex; Jäckle, Hans W.

    Time-resolved chemical ionization mass spectrometry (CIMS) has been used to investigate the variations of the mixing ratios of benzene, toluene and the C 2-benzenes (xylenes and ethyl benzene) in automotive exhaust during transient engine operation. A significant increase of the benzene/toluene ratios from 0.35 to 1.31 (median) was found upon introduction of a catalytic converter system. A preliminary emission model was developed from these test stand measurements to simulate benzene/toluene ratios of passenger car fleets with variable proportions of three-way catalyst vehicles. Although only the emissions of gasoline-driven passenger cars have been considered so far, the predicted increase of the benzene/toluene ratios during the introduction period of the three-way catalyst from 1980 to 2000 is in good agreement with the observed increase of the atmospheric benzene/toluene ratio measured at a suburban monitoring site (Dübendorf, Switzerland) which is strongly influenced by road traffic emissions. At this site, the atmospheric concentrations of benzene and alkyl benzenes have been detected at hourly intervals since 1993. A steady decrease of the yearly mean from 3.54 to 2.00 ppb for toluene and from 2.87 to 1.33 ppb for the sum of C 2-benzenes was found from 1994 to 1998, respectively, when the proportion of three-way catalyst passenger cars increased from 60 to 82%. Nevertheless, the mean benzene concentration was only affected to a small degree (from 1.10 to 0.97 ppb) within the same period of time. Thus, the observed increase of the atmospheric benzene/toluene-mixing ratios from 0.32 to 0.58 (mean) is in good agreement with the predicted values from the presented emission model. Reduced catalyst conversion efficiency for benzene with respect to alkylated benzenes can explain most of the observed increase of the benzene/toluene and benzene/C 2-benzenes mixing rations. In addition, benzene emissions e.g. from the class of light duty vehicles, which are operated more frequently at sub-optimal combustion conditions, may also contribute to the unexpectedly stable atmospheric benzene concentration at the investigated suburban monitoring site.

  19. High concentration suspended sediment measurements using time domain reflectometry

    Science.gov (United States)

    Chung, Chih-Chung; Lin, Chih-Ping

    2011-04-01

    SummaryThe existing methods of suspended sediment concentration (SSC) monitoring provide a measurement accuracy significantly influenced by the particle size of suspended sediments, function only under limited measurement range and are not cost effective for field maintenance as well as wide spatial coverage. The paper introduces an innovative SSC monitoring methodology based upon time domain reflectometry (TDR), especially emphasizing on optimum TDR measurement accuracy investigated theoretically and experimentally. Pertinent probe design, probe calibration, as well as data reduction procedures were proposed. Ultimately, the approach can achieve the measurement accuracy to adapt the derived hardware resolution and beyond. In addition, the performance evaluation was carried out considering possible influence factors including water salinity, sediment types and particle sizes, and leading cable lengths. TDR SSC measurements indicate insensitive to sediment particle sizes. After proper calibration, the measurements are also insensitive to water electrical conductivity and not affected by leading cable resistances. There are further advantages of the TDR method including high measurement range from 2 to at least 300 g L -1, easy calibration, robustness, maintainability, and cost-effective multiplexing.

  20. Sickle hemoglobin polymer melting in high concentration phosphate buffer.

    Science.gov (United States)

    Louderback, J G; Ballas, S K; Kim-Shapiro, D B

    1999-01-01

    Sickle cell hemoglobin (HbS) prepared in argon-saturated 1.8 M phosphate buffer was rapidly mixed with carbon monoxide (CO)-saturated buffer. The binding of CO to the sickle hemoglobin and the simultaneous melting of the hemoglobin polymers were monitored by transmission spectroscopy (optical absorption and turbidity). Changes in the absorption profile were interpreted as resulting from CO binding to deoxy-HbS while reduced scattering (turbidity) was attributed to melting (depolymerization) of the HbS polymer phase. Analysis of the data provides insight into the mechanism and kinetics of sickle hemoglobin polymer melting. Conversion of normal deoxygenated, adult hemoglobin (HbA) in high concentration phosphate buffer to the HbA-CO adduct was characterized by an average rate of 83 s-1. Under the same conditions, conversion of deoxy-HbS in the polymer phase to the HbS-CO adduct in the solution phase is characterized by an average rate of 5.8 s-1 via an intermediate species that grows in with a 36 s-1 rate. Spectral analysis of the intermediate species suggests that a significant amount of CO may bind to the polymer phase before the polymer melts. PMID:10096916

  1. Pumping power station ash as a high concentration slurry

    Energy Technology Data Exchange (ETDEWEB)

    Bunn, T.F.; Jones, M.G.; Wheeler, C.A. [Newcastle Univ. (Australia). Centre for Bulk Solids and Particulate Technologies and TUNRA bulk solids

    2010-07-01

    This paper considered the pumping characteristics of a high concentration slurry comprised of ash from a power station. A rotary viscosimeter and small-scale pumping test rig was used to determine the pressure drop characteristics of pumping a mixture of fly ash and bottom ash with a twin cylinder piston pump fitted with an S transfer tube output system in a 150 mm pipeline with a flow rate of 100 m{sup 3} per hour at a maximum pressure of 6 MPa. The pilot plant consisted of a variable speed Bredel hose pump with a flow rate of 24 m{sup 3} per hour at a pressure of 500 kPa and a 50 mm pipeline. Pumping tests were conducted at different ratios as well as to determine the addition of extra water and wet bottom ash. An examination of the pilot pumping plant data indicated a shear rate of 84 per second and a pseudo shear stress of 26 Pa. Results of the study suggested that the fly ash and bottom ash slurries are heterogenous slurries. The rotary viscosimeter underestimated the pumpability of the slurry due to the fact that the viscometer can only accurately measure homogenous slurries. 2 refs., 5 tabs., 15 figs.

  2. Effect of alcohol chain length, concentration and polarity on separations in high-performance liquid chromatography using bonded cyclodextrin columns.

    Science.gov (United States)

    Atamna, I Z; Muschik, G M; Issaq, H J

    1990-01-19

    The effect of alcohol chain length, concentration and polarity on separation in high-performance liquid chromatography using beta-cyclodextrin-bonded silica is discussed. The results show that retention times cannot be predicted merely from the polarity of the binary mobile phase. Although organic modifiers with the same physico-chemical properties and from the same solvent group were used, the retention times obtained using binary mobile phases having the same polarity, were different. It was also observed that normal-chain carbon alcohols gave retention times shorter than those obtained with a branched-chain alcohol (n-propanol vs. isopropanol), and the longer the alcohol chain the shorter the retention times. A plot of ln k' vs. alcohol volume fraction for benzene, toluene, ethylbenzene, propylbenzene, butylbenzene, 1-phenylhexane and 1-phenyloctane gave a linear relationship in methanol, ethanol and propanol (except for 1-phenylhexane). A non-linear relationship was obtained for all the solutes in isopropanol, tert.-butanol and 1-butanol, in the alcohol volume fraction studied. PMID:2324212

  3. Benzene and sulfide removal from groundwater treated in a microbial fuel cell.

    Science.gov (United States)

    Rakoczy, Jana; Feisthauer, Stefan; Wasmund, Kenneth; Bombach, Petra; Neu, Thomas R; Vogt, Carsten; Richnow, Hans H

    2013-12-01

    Sulfidic benzene-contaminated groundwater was used to fuel a two-chambered microbial fuel cell (MFC) over a period of 770 days. We aimed to understand benzene and sulfide removal processes in the anoxic anode chamber and describe the microbial community enriched over the operational time. Operated in batch feeding-like circular mode, supply of fresh groundwater resulted in a rapid increase in current production, accompanied by decreasing benzene and sulfide concentrations. The total electron recoveries for benzene and sulfide were between 18% and 49%, implying that benzene and sulfide were not completely oxidized at the anode. Pyrosequencing of 16S rRNA genes from the anode-associated bacterial community revealed the dominance of ?-Proteobacteria (31%), followed by ?-Proteobacteria, Bacteroidetes, ?-Proteobacteria, Chloroflexi, and Firmicutes, most of which are known for anaerobic metabolism. Two-dimensional compound-specific isotope analysis demonstrated that benzene degradation was initiated by monohydroxylation, probably triggered by small amounts of oxygen which had leaked through the cation exchange membrane into the anode chamber. Experiments with [(13)C(6) ]-benzene revealed incorporation of (13)C into fatty acids of mainly Gram-negative bacteria, which are therefore candidates for benzene degradation. Our study demonstrated simultaneous benzene and sulfide removal by groundwater microorganisms which use an anode as artificial electron acceptor, thereby releasing an electrical current. PMID:23775304

  4. Short-term monitoring of benzene air concentration in an urban area: a preliminary study of application of Kruskal-Wallis non-parametric test to assess pollutant impact on global environment and indoor / Monitoraggio a breve termine delle concentrazioni di benzene in aria urbana: uno studio preliminare di applicazione del test Kruskall-Wallis per valutare l'impatto dell'inquinante sull'ambiente esterno ed interno

    Scientific Electronic Library Online (English)

    Maria Chiara, Mura; Marco, De Felice; Roberta, Morlino; Sergio, Fuselli.

    2010-12-01

    Full Text Available In step with the need to develop statistical procedures to manage small-size environmental samples, in this work we have used concentration values of benzene (C6H6), concurrently detected by seven outdoor and indoor monitoring stations over 12 000 minutes, in order to assess the representativeness o [...] f collected data and the impact of the pollutant on indoor environment. Clearly, the former issue is strictly connected to sampling-site geometry, which proves critical to correctly retrieving information from analysis of pollutants of sanitary interest. Therefore, according to current criteria for network-planning, single stations have been interpreted as nodes of a set of adjoining triangles; then, a) node pairs have been taken into account in order to estimate pollutant stationarity on triangle sides, as well as b) node triplets, to statistically associate data from air-monitoring with the corresponding territory area, and c) node sextuplets, to assess the impact probability of the outdoor pollutant on indoor environment for each area. Distributions from the various node combinations are all non-Gaussian, in the consequently, Kruskal-Wallis (KW) non-parametric statistics has been exploited to test variability on continuous density function from each pair, triplet and sextuplet. Results from the above-mentioned statistical analysis have shown randomness of site selection, which has not allowed a reliable generalization of monitoring data to the entire selected territory, except for a single "forced" case (70%); most important, they suggest a possible procedure to optimize network design.

  5. On separation of thorium concentrate from high concentrated calcium chloride solutions

    International Nuclear Information System (INIS)

    Extraction, washing, re-extraction and precipitation of thorium(IV) from re-extract in hydrochloric acid engineering of perovskite are studied. Conditions for the preparation of concentrate with the content of ThO2 near 85 mas.% are recommended. Lowering of Vorg:Vwat to (0.5-0.6):1 values during the extraction is needed for the preparation of rich by Th(IV) concentrate. Re-extraction of Th(IV) from organic phase is recommended to realize at Vorg:Vwat =1:(1-1.5), and its precipitation from re-extract - at pH?5

  6. Mo-modified Pd/Al?O? catalysts for benzene catalytic combustion.

    Science.gov (United States)

    He, Zhanfeng; He, Zhanrong; Wang, Dan; Bo, Qifei; Fan, Ting; Jiang, Yi

    2014-07-01

    Mo-modified Pd/Al?O? catalysts were prepared by an impregnation method and tested for the catalytic combustion of benzene. The catalysts were characterized by N? isothermal adsorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption of NH? (NH?-TPD), H? temperature-programmed reduction (H?-TPR), and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The results showed that the addition of Mo effectively improved the activity and stability of the Pd/Al?O? catalyst by increasing the dispersion of Pd active components, changing the partial oxidation state of palladium and increasing the oxygen species concentration on the surface of catalyst. In the case of the Pd-Mo/Al?O? catalyst, benzene conversion of 90% was obtained at temperatures as low as 190°C, which was 45°C lower than that for similar performance with the Pd/Al?O? catalyst. Moreover, the 1.0% Pd-5% Mo/Al?O? catalyst was more active than the 2.0% Pd/Al?O? catalyst. It was concluded that Pd and Mo have a synergistic effect in benzene catalytic combustion. PMID:25079997

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-11-15

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

  8. The Solubility of Phenylborate Compounds in Benzene

    International Nuclear Information System (INIS)

    The original goal of this scoping study was to determine if the solubility of sodium and potassium tetraphenylborates in benzene was sufficiently large to justify designing and performing kinetic studies on a benzene-phase catalytic reaction

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

    International Nuclear Information System (INIS)

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

  10. The preparation of alkyl benzene sulphonate, 14C-labelled in the benzene ring

    International Nuclear Information System (INIS)

    The paper describes the preparation of sodium alkyl sulphonate 14C-labelled in the benzene ring. The composition of the resultant product largely corresponded to that of a technical alkyl benzene sulphonate. It was obtained by sulphonation of alkyl benzene which, in turn, had been made by reacting 14C-labelled benzene with a technical olefin fraction. (orig.)

  11. Anaerobic Benzene Oxidation by Geobacter Species

    OpenAIRE

    Zhang, Tian; Bain, Timothy S.; Nevin, Kelly P.; Barlett, Melissa A.; Lovley, Derek R.

    2012-01-01

    The abundance of Geobacter species in contaminated aquifers in which benzene is anaerobically degraded has led to the suggestion that some Geobacter species might be capable of anaerobic benzene degradation, but this has never been documented. A strain of Geobacter, designated strain Ben, was isolated from sediments from the Fe(III)-reducing zone of a petroleum-contaminated aquifer in which there was significant capacity for anaerobic benzene oxidation. Strain Ben grew in a medium with benzen...

  12. Species differences in the metabolism of benzene.

    OpenAIRE

    Henderson, R. F.

    1996-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-10-15

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

  14. ATMOSPHERIC BENZENE DEPLETION BY SOIL MICROORGANISMS

    Science.gov (United States)

    Gaseous benzene was rapidly depleted in exposure chambers containing viable soils and plants. When separate components of the system were analyzed, no benzene was detected in soils, plants, or water. Soil microorganisms were shown to be responsible for metabolizing benzene, yield...

  15. Localization of charge carriers in materials with high polaron concentration

    Energy Technology Data Exchange (ETDEWEB)

    Titov, A.N.; Yarmoshenko, Yu.M.; Titova, S.G.; Krasavin, L.S.; Neumann, M

    2003-04-01

    The influence of polaron concentration on the type of transition from band to activate conductivity has been investigated. For a single polaron in the crystal lattice or for material with polaron concentration higher than the percolation threshold, such a transition is continuous, in accordance with theory. However, for intermediate cases this process becomes step-like, because the rapid increase of density of states at Fermi level leads to a change of polaron characteristics. These suppositions are illustrated by experimental results (XPS-spectra, crystal structure analysis, DC conductivity) for intercalation compounds based on titanium dichalcogenides.

  16. High level ?-dosimetry using CaSO4:Dy phosphor with high Dy-concentration

    International Nuclear Information System (INIS)

    It has been observed that the thermoluminescent traps in CaSO4:Dy phosphor with a high concentration of activator (2.0 mol% Dy) compared to that of normal samples (containing 0.05 mol% Dy) show a better stability and a lesser tendency towards saturation to ?-radiation. This effect has been observed for the main dosimetric peak (approximately 2250C) as well as for the high temperature peak (approximately 3900C). Thus by using 3900C TL peak in CaSO4:Dy (2.0 mol%) it was possible to make high level ? dose measurements in the range from 2 x 102 to 3 x 106 Gy. The 3900C TL peak in CaSO4:Dy (2.0 mol%) samples increases non-linearly with dose and does not show any tendency towards saturation at least up to 3 x 106 Gy- the dose level studied. However, the corresponding high temperature peak in the normal samples (0.05 mol% Dy) shows saturation in its TL response above a ?-dose of 1.18 x 106 Gy. In addition, a high temperature TL peak at 5720C which is only observed for the high activator concentration sample increases non-linearly with dose and does not show saturation up to the ?-dose of 3 x 106 Gy. Investigations on photo-transferred TL of high temperature peaks as a function of ?-dose were also carried out for both the types of samples. (author)

  17. Role of delocalization in benzene

    Energy Technology Data Exchange (ETDEWEB)

    Glendening, E.D.; Faust, R.; Streitwieser, A.; Vollhardt, K.P.C. (Univ. of California, Berkeley, CA (United States) Lawrence Berkeley Lab., CA (United States)); Weinbold, F. (Univ. of Wisconsin, Madison, WI (United States))

    1993-11-17

    The influence of [pi] delocalization on the geometry of benzene is examined at the ab initio SCF level of theory. We find that benzene favors a bond alternating geometry when its canonical [pi] MOs are replaced by three localized ethylenic orbitals, revealing that delocalization is in part responsible for the equilibrium symmetric structure. In apparent contrast, a [sigma]-[pi] energy partitioning analysis suggests that the benzene [sigma] framework is responsible for the symmetric structure, the [pi] system preferring a distorted geometry. Shaik et al. have therefore concluded that delocalization in not an important symmetrizing force in this molecule. We show, however, that the [pi] energy component contains a sizable and strongly geometry dependent contribution from the localized (Kekule) wave function. Thus, it appears to be misleading to judge the nature of delocalization based on a [sigma]-[pi] partition. We conclude that delocalization effects act to strongly stabilize symmetric benzene in essential accord with the concepts of classical resonance theory. 27 refs., 6 figs., 2 tabs.

  18. Stability of Human Telomere Quadruplexes at High DNA Concentrations.

    Czech Academy of Sciences Publication Activity Database

    Kejnovská, Iva; Vorlí?ková, Michaela; Brázdová, Marie; Sagi, J.

    2014-01-01

    Ro?. 101, ?. 4 (2014), s. 428-438. ISSN 0006-3525 R&D Projects: GA ?R(CZ) GAP205/12/0466 Institutional support: RVO:68081707 Keywords : quadruplex * DNA concentration * folding topology Subject RIV: BO - Biophysics Impact factor: 2.288, year: 2013

  19. Unusually high concentrations in a fatal GHB case.

    Science.gov (United States)

    Kintz, Pascal; Villain, Marion; Pélissier, Anne-Laure; Cirimele, Vincent; Leonetti, Georges

    2005-09-01

    The first case in France involving a fatal overdose resulting from the ingestion of gamma-hydroxybutyrate (GHB) is presented. GHB was tested by gas chromatography-mass spectrometry (GC-MS) after precipitation. Briefly, 20 microL of body fluids (blood, bile, urine, gastric contents, or vitreous humor) was pipetted in a glass tube, followed by 20 microL GHB-d6 and 45 microL acetonitrile. After vortex mixing and centrifuging, the supernatant was collected and evaporated to dryness. The residue was derivatized with BSTFA with 1% TMCS for 20 min at 70 degrees C. After injection on a 30-m HP5 MS capillary column, GHB (m/z 233, 204, and 147) and GHB-d6 (m/z 239) were identified by MS. GHB was also tested in pubic hair after incubation in 0.01 N NaOH, neutralization, acidification, extraction in ethyl acetate and derivatization with MTBSTFA, using GC-MS-MS. GHB was positive in all the tested specimens, with the following concentrations 2937, 33,727, 1800, and 2856 mg/L in femoral blood, urine, bile, and vitreous humor, respectively. This seems to be the highest blood concentration ever observed. Postmortem redistribution appears weak, as the concentration in cardiac blood was 3385 mg/L (cardiac blood/femoral blood ratio of 1.15). Oral route was suggested with GHB at 7.08 g in 100 mL of gastric contents. Pubic hair analysis clearly indicated chronic GHB abuse, with concentrations along the shaft in the range 19.4 to 25.0 ng/mg (in comparison with physiological concentrations < 2 ng/mg). Methylenedioxymethamphetamine was present in femoral blood at 144 ng/mL. These results are consistent with an acute fatal overdose of GHB. PMID:16168184

  20. Study of the thermal diffusion behavior of alkane/benzene mixtures by thermal diffusion forced rayleigh scattering experiments and lattice model calculations.

    Science.gov (United States)

    Polyakov, Pavel; Luettmer-Strathmann, Jutta; Wiegand, Simone

    2006-12-28

    In this work the thermal diffusion behavior of binary mixtures of linear alkanes (heptane, nonane, undecane, tridecane, pentadecane, heptadecane) in benzene has been investigated by thermal diffusion forced Rayleigh scattering (TDFRS) for a range of concentrations and temperatures. The Soret coefficient ST of the alkane was found to be negative for these n-alkane/benzene mixtures indicating that the alkanes are enriched in the warmer regions of the liquid mixtures. For the compositions investigated in this work, the magnitude of the Soret coefficient decreases with increasing chain length and increasing alkane content of the mixtures. The temperature dependence of the Soret coefficient depends on mixture composition and alkane chain length; the slope of ST versus temperature changes from positive to negative with increasing chain length at intermediate compositions. To study the influence of molecular architecture on the Soret effect, mixtures of branched alkanes (2-methylhexane, 3-methylhexane, 2,3-dimethylpentane, 2,4-dimethylpentane, 2,2,3-trimethylbutane, and 2,2,4-trimethylpentane) in benzene were also investigated. Our results for the Soret coefficients show that the tendency for the alkanes to move to the warmer regions of the fluid decreases with increasing degree of branching. The branching effect is so strong that for 2,2,4-trimethylpentane/benzene mixtures the Soret coefficient changes sign at high alkane content and that equimolar 2,2,3-trimethylbutane/benzene mixtures have positive Soret coefficients in the investigated temperature range. In order to investigate the effect of molecular interactions on thermal diffusion, we adapted a recently developed two-chamber lattice model to n-alkane/benzene mixtures. The model includes the effects of chain-length, compressibility, and orientation dependence of benzene-benzene interactions and yields good qualitative predictions for the Soret effect in n-alkane/benzene mixtures. For the branched isomers, we find some correlations between the moments of inertia of the molecules and the Soret coefficients. PACS numbers: 66.10.Cb, 61.25.Hq. PMID:17181279

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

    International Nuclear Information System (INIS)

    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/m3 for benzene, 18,3 and 253 mg/m3 for toluene and 11,8 and 122,2 mg/m3 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/m3 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 mixtureindustry when it is considered the mixture of the three solvents

  2. 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)

    Highlights: • Co3O4 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 Co3O4 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

  3. Simultaneous determination of the urinary metabolites of benzene, toluene, xylene and styrene using high-performance liquid chromatography/hybrid quadrupole time-of-flight mass spectrometry.

    Science.gov (United States)

    Marchese, Stefano; Curini, Roberta; Gentili, Alessandra; Perret, Daniela; Rocca, Lucia Mainero

    2004-01-01

    A simple and rapid method using reversed-phase liquid chromatography/tandem mass spectrometry (LC/MS/MS) for the simultaneous determination of the urinary metabolites of benzene, toluene, xylene and styrene in human urine specimens and standard solutions is described. A hybrid quadrupole/time-of-flight (QqTOF) mass spectrometer was compared for the determination of metabolite of aromatic solvents in urine samples. The metabolites selected were: trans,trans-muconic acid, hippuric acid, o-, m- and p-methylhippuric acid and phenylglyoxylic acid. The compounds were well separated from each other on narrow-bore 1-mm i.d. reversed-phase LC C-18 columns. Average recoveries for loading 100 microL of urine samples varied from 88-110% and the quantification limits were less than 30 ng/mL for each analyte (3 ng/mL for trans,trans-muconic acid). The qualitative information obtained (mass accuracy, resolution and full-scan spectra) with the QqTOF mass spectrometer allows a secure identification of analytes in biological matrices. PMID:14755610

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

    Science.gov (United States)

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

    2014-04-25

    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 Co3O4 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. PMID:24725745

  5. High-performance flat-panel solar thermoelectric generators with high thermal concentration

    Science.gov (United States)

    Kraemer, Daniel; Poudel, Bed; Feng, Hsien-Ping; Caylor, J. Christopher; Yu, Bo; Yan, Xiao; Ma, Yi; Wang, Xiaowei; Wang, Dezhi; Muto, Andrew; McEnaney, Kenneth; Chiesa, Matteo; Ren, Zhifeng; Chen, Gang

    2011-07-01

    The conversion of sunlight into electricity has been dominated by photovoltaic and solar thermal power generation. Photovoltaic cells are deployed widely, mostly as flat panels, whereas solar thermal electricity generation relying on optical concentrators and mechanical heat engines is only seen in large-scale power plants. Here we demonstrate a promising flat-panel solar thermal to electric power conversion technology based on the Seebeck effect and high thermal concentration, thus enabling wider applications. The developed solar thermoelectric generators (STEGs) achieved a peak efficiency of 4.6% under AM1.5G (1?kW?m-2) conditions. The efficiency is 7-8 times higher than the previously reported best value for a flat-panel STEG, and is enabled by the use of high-performance nanostructured thermoelectric materials and spectrally-selective solar absorbers in an innovative design that exploits high thermal concentration in an evacuated environment. Our work opens up a promising new approach which has the potential to achieve cost-effective conversion of solar energy into electricity.

  6. Dimerization in Highly Concentrated Solutions of Phosphoimidazolide Activated Mononucleotides

    Science.gov (United States)

    Kanavarioti, Anastassia

    1997-01-01

    Phosphoimidazolide activated ribomononucleotides (*pN) are useful substrates for the non-enzymatic synthesis of polynucleotides. However, dilute neutral aqueous solutions of *pN typically yield small amounts of dimers and traces of polymers; most of *pN hydrolyzes to yield nucleoside 5'-monophosphate. Here we report the self-condensation of nucleoside 5'-phosphate 2- methylimidazolide (2-MeImpN with N = cytidine, uridine or guanosine) in the presence of Mg2(+) in concentrated solutions, such as might have been found in an evaporating lagoon on prebiotic Earth. The product distribution indicates that oligomerization is favored at the expense of hydrolysis. At 1.0 M, 2-MelmpU and 2-MelmpC produce about 65% of oligomers including 4% of the 3',5'-Iinked dimer. Examination of the product distribution of the three isomeric dimers in a self-condensation allows identification of reaction pathways that lead to dimer formation. Condensations in a concentrated mixture of all three nucleotides (U,C,G mixtures) is made possible by the enhanced solubility of 2-MeImpG in such mixtures. Although percent yield of intemucleotide linked dimers is enhanced as a function of initial monomer concentration, pyrophosphate dimer yields remain practically unchanged at about 20% for 2-MelmpU, 16% for 2-MeImpC and 25% of the total pyrophosphate in the U,C,G mixtures. The efficiency by which oligomers are produced in these concentrated solutions makes the evaporating lagoon scenario a potentially interesting medium for the prebiotic synthesis of dimers and short RNAs.

  7. High concentrations of pepsin in bronchoalveolar lavage fluid from children with cystic fibrosis are associated with high interleukin-8 concentrations.

    LENUS (Irish Health Repository)

    McNally, P

    2012-02-01

    BACKGROUND: Gastro-oesophageal reflux is common in children with cystic fibrosis (CF) and is thought to be associated with pulmonary aspiration of gastric contents. The measurement of pepsin in bronchoalveolar lavage (BAL) fluid has recently been suggested to be a reliable indicator of aspiration. The prevalence of pulmonary aspiration in a group of children with CF was assessed and its association with lung inflammation investigated. METHODS: This was a cross-sectional case-control study. BAL fluid was collected from individuals with CF (n=31) and healthy controls (n=7). Interleukin-8 (IL-8), pepsin, neutrophil numbers and neutrophil elastase activity levels were measured in all samples. Clinical, microbiological and lung function data were collected from medical notes. RESULTS: The pepsin concentration in BAL fluid was higher in the CF group than in controls (mean (SD) 24.4 (27.4) ng\\/ml vs 4.3 (4.0) ng\\/ml, p=0.03). Those with CF who had raised pepsin concentrations had higher levels of IL-8 in the BAL fluid than those with a concentration comparable to controls (3.7 (2.7) ng\\/ml vs 1.4 (0.9) ng\\/ml, p=0.004). Within the CF group there was a moderate positive correlation between pepsin concentration and IL-8 in BAL fluid (r=0.48, p=0.04). There was no association between BAL fluid pepsin concentrations and age, sex, body mass index z score, forced expiratory volume in 1 s or Pseudomonas aeruginosa colonisation status. CONCLUSIONS: Many children with CF have increased levels of pepsin in the BAL fluid compared with normal controls. Increased pepsin levels were associated with higher IL-8 concentrations in BAL fluid. These data suggest that aspiration of gastric contents occurs in a subset of patients with CF and is associated with more pronounced lung inflammation.

  8. Catalytically-mediated denitration of highly HNO3 concentrated solutions

    International Nuclear Information System (INIS)

    Chemical denitration by formic acid aims to reduce nuclear fuel reprocessing nitric wastes volume and concentration. The use of Pt/SiO2 catalysts suppresses the induction period of the reaction between formic and nitric acids. This is due to the fast initial catalytic generation of HNO2 from HNO3 on Pt/SiO2, which become further the active species in the homogeneous phase. It is proposed that HNO2 generation passivates the Pt metal phase, which is in turn reactivated by formic acid. (authors)

  9. 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.

  10. Benzene formation in the inner regions of protostellar disks

    CERN Document Server

    Woods, P M; Woods, Paul M.; Willacy, Karen

    2006-01-01

    Benzene (c-C6H6) formation in the inner 3 AU of a protostellar disk can be efficient, resulting in high abundances of benzene in the midplane region. The formation mechanism is different to that found in interstellar clouds and in protoplanetary nebulae, and proceeds mainly through the reaction between allene (C3H4) and its ion. This has implications for PAH formation, in that some fraction of PAHs seen in the solar system could be native rather than inherited from the interstellar medium.

  11. Adverse Effect of High Glucose Concentration on Stem Cell Therapy

    Directory of Open Access Journals (Sweden)

    Najmaldin Saki

    2013-07-01

    Full Text Available Stem cell therapy could have great potential for the treatment of a wide variety of diseases. Stem cells might have the ability to differentiate into a widespread cell types, and to repopulate and revitalize the damaged cells with healthy tissue, and improve its performance. We provide here the evidence supporting the critical use of stem cell as a treatment in disease conditions existing with high glucose complaint such as diabetes. The reduction of glucose stimulated cell proliferation and high glucose enhanced apoptosis in rat model, which may be a problem in therapeutic strategies based on ex vivo expansion of stem cell, and may also propagate the development of osteoporosis in high glucose complaint such as diabetes. This leads to the hypothesis that, high glucose could be more deleterious to stem cell therapy that may be due to the aggravation of oxidative stress triggered by high glucose. These findings may help to understand the possible reasons associated with high glucose induced detrimental effects on stem cells as well as provide novel therapeutic strategies for preventing the adverse effects of glucose on the development and progression of stem cells in patients with diabetes.

  12. Monitoring benzene formation from benzoate in model systems by proton transfer reaction-mass spectrometry

    Science.gov (United States)

    Aprea, Eugenio; Biasioli, Franco; Carlin, Silvia; Märk, Tilmann D.; Gasperi, Flavia

    2008-08-01

    The presence of benzene in food and in particular in soft drinks has been reported in several studies and should be considered in fundamental investigations about formation of this carcinogen compound as well as in quality control. Proton transfer reaction-mass spectrometry (PTR-MS) has been used here for rapid, direct quantification of benzene and to monitor its formation in model systems related to the use of benzoate, a common preservative, in presence of ascorbic acid: a widespread situation that yields benzene in, e.g., soft drinks and fruit juices. Firstly, we demonstrate here that PTR-MS allows a rapid determination of benzene that is in quantitative agreement with independent solid phase micro-extraction/gas chromatography (SPME/GC) analysis. Secondly, as a case study, the effect of different sugars (sucrose, fructose and glucose) on benzene formation is investigated indicating that they inhibit its formation and that this effect is enhanced for reducing sugars. The sugar-induced inhibition of benzene formation depends on several parameters (type and concentration of sugar, temperature, time) but can be more than 80% in situations that can be expected in the storage of commercial soft drinks. This is consistent with the reported observations of higher benzene concentrations in sugar-free soft drinks.

  13. Review of Quantitative Surveys of the Length and Stability of MTBE, TBA, and Benzene Plumes in Groundwater at UST Sites.

    Science.gov (United States)

    Connor, John A; Kamath, Roopa; Walker, Kenneth L; McHugh, Thomas E

    2015-03-01

    Quantitative information regarding the length and stability condition of groundwater plumes of benzene, methyl tert-butyl ether (MTBE), and tert-butyl alcohol (TBA) has been compiled from thousands of underground storage tank (UST) sites in the United States where gasoline fuel releases have occurred. This paper presents a review and summary of 13 published scientific surveys, of which 10 address benzene and/or MTBE plumes only, and 3 address benzene, MTBE, and TBA plumes. These data show the observed lengths of benzene and MTBE plumes to be relatively consistent among various regions and hydrogeologic settings, with median lengths at a delineation limit of 10?µg/L falling into relatively narrow ranges from 101 to 185?feet for benzene and 110 to 178?feet for MTBE. The observed statistical distributions of MTBE and benzene plumes show the two plume types to be of comparable lengths, with 90th percentile MTBE plume lengths moderately exceeding benzene plume lengths by 16% at a 10-µg/L delineation limit (400?feet vs. 345?feet) and 25% at a 5-µg/L delineation limit (530?feet vs. 425?feet). Stability analyses for benzene and MTBE plumes found 94 and 93% of these plumes, respectively, to be in a nonexpanding condition, and over 91% of individual monitoring wells to exhibit nonincreasing concentration trends. Three published studies addressing TBA found TBA plumes to be of comparable length to MTBE and benzene plumes, with 86% of wells in one study showing nonincreasing concentration trends. PMID:25040137

  14. Intermolecular interactions in solid benzene

    Science.gov (United States)

    Kearley, G. J.; Johnson, M. R.; Tomkinson, J.

    2006-01-01

    The lattice dynamics and molecular vibrations of benzene and deuterated benzene crystals are calculated from force constants derived from density-functional theory (DFT) calculations and compared with measured inelastic neutron-scattering spectra. A very small change (0.5%) in lattice parameter is required to obtain real lattice-mode frequencies across the Brillouin zone. There is a strong coupling between wagging and breathing modes away from the zone center. This coupling and sensitivity to cell size arises from two basic interactions. Firstly, comparatively strong interactions that hold the benzene molecules together in layers. These include an intermolecular interaction in which H atoms of one molecule link to the center of the aromatic ring of a neighboring molecule. The layers are held to each other by weaker interactions, which also have components that hold molecules together within a layer. Small changes in the lattice parameters change this second type of interaction and account for the changes to the lattice dynamics. The calculations also reveal a small auxetic effect in that elongation of the crystal along the b axis leads to an increase in internal pressure in the ac plane, that is, elongation in the b direction induces expansion in the a and c directions.

  15. Geogenic sources of benzene in aquifers used for public supply, California

    Science.gov (United States)

    Belitz, Kenneth; Landon, Matthew K.

    2012-01-01

    Statistical evaluation of two large statewide data sets from the California State Water Board's Groundwater Ambient Monitoring and Assessment Program (1973 wells) and the California Department of Public Health (12417 wells) reveals that benzene occurs infrequently (1.7%) and at generally low concentrations (median detected concentration of 0.024 ?g/L) in groundwater used for public supply in California. When detected, benzene is more often related to geogenic (45% of detections) than anthropogenic sources (27% of detections). Similar relations are evident for the sum of 17 hydrocarbons analyzed. Benzene occurs most frequently and at the highest concentrations in old, brackish, and reducing groundwater; the detection frequency was 13.0% in groundwater with tritium 1600 ?S/cm, and anoxic conditions. This groundwater is typically deep (>180 m). Benzene occurs somewhat less frequently in recent, shallow, and reducing groundwater; the detection frequency was 2.6% in groundwater with tritium ?1 pCi/L, depth benzene include: higher concentrations and detection frequencies with increasing well depth, groundwater age, and proximity to oil and gas fields; and higher salinity and lower chloride/iodide ratios in old groundwater with detections of benzene, consistent with interactions with oil-field brines.

  16. SELENIUM EFFECT UPON THE RATS' HEMATOPOIESIS IN THE SUBACUTE BENZENE INTOXICATION

    Directory of Open Access Journals (Sweden)

    Pavle Randjelovic

    2001-03-01

    Full Text Available The antioxidants (selenium, vitamins C and E stabilize the cell membrane andprotect the cells from the action of free radicals. On the other hand, the antioxidantsreduce the effects of chemical and physical agenls. Bcsidcs, selenium has animportant role in Transporting electrons in the mitochondria and il is necessary for iheglulathione peroxidase function in the protection from apoplhosis. Benzene is auniversal solvent and has a wide application in chemical industry. Its toxicity ismanifested in the damages done to the central nervous syslem, liver, kidneys andhematopoiesis system. Tn this experiment the Wistar rats were used that wereclassified in three experimental groups regarding the quantity of the receivedselenium. Each group comprised ten animals of both sexes and after two weeks'treatment by selenium of 4,8 and 16 mcg, the animals had received benzene byinlraperiloneal administration in the dose of 1,2 ml/kg of the body weight. Thecounting of the shaped blood elements was done after the selenium pretreatment andafter the benzene intoxication. The obtained results poinl to increased number of alithe blood elements after the selenium pretreatment while after benzene adminislrationthere was a drastic drop of the number of erylhrocyles and leukocytes alongwith moderate lhrombocylopenia. After the sacrifice, Ihe hematopoiesis organs weretaken. The hislological findings of the bone marrow show the emergence ofdisturbances, especially of the red sort cells as well as an obvious fat degeneration which is particularly conspicuous in the second and third groups of animals. Therewas also some damage done to the spleen, especially of its red pulp along with thepresence of a greater number of fresh erythrocytes in the second and third groups.Only the changes were more drastic in the third group. The obtained results show thatselenium in higher concentrations increases the number of erytrocytes andleukocytes which proves that it stimulates highly-proliferating cells of the bonemarrow. However, after the intoxication by a sub lethal benzene dose there was a dropof the cells of red and white color but these values are within the normal limits. Thispoints to the fact that the emergence of death is not in any direct correlation with thedisturbances in the hematopoiesis, but death was caused by the damage done to someother vital organs. Despite the fact that selenium prevents the cells' damage, in this?aše its protective effect manifested itself only when it was given in small doses sincethere was no death in this group of animals.

  17. High plasma uric acid concentration: causes and consequences

    Directory of Open Access Journals (Sweden)

    de Oliveira Erick

    2012-04-01

    Full Text Available Abstract High plasma uric acid (UA is a precipitating factor for gout and renal calculi as well as a strong risk factor for Metabolic Syndrome and cardiovascular disease. The main causes for higher plasma UA are either lower excretion, higher synthesis or both. Higher waist circumference and the BMI are associated with higher insulin resistance and leptin production, and both reduce uric acid excretion. The synthesis of fatty acids (tryglicerides in the liver is associated with the de novo synthesis of purine, accelerating UA production. The role played by diet on hyperuricemia has not yet been fully clarified, but high intake of fructose-rich industrialized food and high alcohol intake (particularly beer seem to influence uricemia. It is not known whether UA would be a causal factor or an antioxidant protective response. Most authors do not consider the UA as a risk factor, but presenting antioxidant function. UA contributes to > 50% of the antioxidant capacity of the blood. There is still no consensus if UA is a protective or a risk factor, however, it seems that acute elevation is a protective factor, whereas chronic elevation a risk for disease.

  18. Analysis of high level ozone concentrations using nonparametric methods.

    Science.gov (United States)

    Quintela-del-Río, Alejandro; Francisco-Fernández, Mario

    2011-02-15

    Controlling emissions of air pollutants and establishing air quality objectives to improve and protect ambient air quality are very important tasks of Governments. Ozone (O(3)), one of those pollutants of concern, is not emitted directly into the atmosphere, but is a secondary pollutant produced by reaction between nitrogen dioxide (NO(2)), hydrocarbons and sunlight. High levels of ozone can produce harmful effects on human health and the environment in general. Therefore, the study of extreme values of ozone represents an important topic of research in environmental problems. Classical extreme value theory has been usually used in air-pollution studies. It consists of fitting a parametric generalized extreme value (GEV) distribution to a data set of extreme values and using the estimated distribution to compute quantities like the probability of exceedance, the quantiles, the return levels or the mean return periods. In this paper, we propose nonparametric methods to estimate those quantities. Additionally, nonparametric estimators of the trends of very high values of ozone are proposed. The nonparametric estimators are applied to real samples of maximum ozone values obtained from several monitoring stations belonging to the Automatic Urban and Rural Network (AURN) from the UK. Results show that nonparametric estimators work satisfactorily, generally outperforming the behaviour of classical parametric estimators. PMID:21195453

  19. Biomonitoring of benzene and 1,3-butadiene exposure and early biological effects in traffic policemen

    DEFF Research Database (Denmark)

    Arayasiri, Manaswee; Mahidol, Chulabhorn

    2010-01-01

    The objective of this study was to determine benzene and 1,3-butadiene exposure through ambient air and personal air monitoring, as well as through biomarkers of exposure, and to evaluate the potential health risk of exposure through the use of biomarkers of early biological effects in central Bangkok traffic policemen. Ambient air concentrations of benzene and 1,3-butadiene at the roadsides were significantly higher than in police offices used as control sites (p

  20. Physical and chemical changes in liquid benzene multiply shocked to 25 GPa

    Science.gov (United States)

    Root, Seth

    Liquid benzene was confined between two optically transparent windows and multiply shock compressed to peak pressures ranging from 0.6 GPa to 25 GPa. Multiple shock compression produced well-defined, uniform pressure states in the benzene and resulted in lower temperatures than the temperatures in single-shock loading. Time-resolved optical spectroscopy and real-time imaging measurements were performed to examine the physical and chemical changes in liquid benzene over several hundred nanoseconds. A complete and thermodynamically consistent equation of state was developed to calculate temperatures, densities, and energies in the shock compressed benzene. The liquid-solid phase transition was examined using single-pass light transmission measurements, direct imaging, and high-resolution Raman spectroscopy. The transmission measurements showed no changes in the transparency of the benzene sample. The resulting images at peak pressure were identical to the images at ambient conditions. High-resolution Raman spectroscopy was performed to examine the changes in the nu2+nu7 C-H stretching modes, which show significant splitting in solid benzene. The C-H spectrum of multiply-shocked liquid benzene showed only a single peak, while the C-H spectrum of solid benzene shows significant splitting between the nu 2 and nu7 C-H stretching modes. The results from the transmission, imaging, and Raman experiments show that the liquid-solid phase transition of benzene does not occur on sub-mus time scales even though the benzene is in a pressure-temperature state corresponding to the solid phase. Time-resolved Raman spectroscopy measurements were performed to 24.5 GPa peak pressures to examine shock-induced chemical changes in benzene. In these measurements, the nu1 ring-breathing mode and the nu 2+nu7 C-H stretching modes were monitored to examine pressure-temperature effects on the C-C and C-H bonds. Up to 20 GPa, the Raman spectra showed shifting and broadening in both the nu2+nu7 C-H stretching and nu1 ring-breathing modes. At 24.5 GPa, the Raman modes become indistinguishable from an increasing background resulting from a chemical change. Analysis of the Raman data indicated these changes were unlikely to be caused by bond dissociation. Comparison to statically compressed solid benzene and theoretical models suggest that multiply-shocked liquid benzene rapidly polymerizes through cycloaddition processes into a network of intermolecularly bonded benzene rings.

  1. Benzene and leukemia: an epidemiologic risk assessment.

    OpenAIRE

    Rinsky, R. A.

    1989-01-01

    To assess quantitatively the association between benzene and leukemia, we evaluated the rate of mortality experienced by a cohort occupationally exposed to benzene. Using data from historical air sampling surveys, we estimated the daily benzene exposure for each member of the cohort. The expected number of leukemia deaths was calculated and compared to the actual number of leukemia deaths that occurred. The overall standardized mortality ratio (SMR) for leukemia was 337. Person-years at risk ...

  2. Genetic susceptibility to benzene toxicity in humans.

    OpenAIRE

    Garte, Seymour; Taioli, Emanuela; Popov, Todor; Bolognesi, Claudia; Farmer, Peter; Merlo, Franco

    2008-01-01

    Human metabolism of benzene involves pathways coded for by polymorphic genes. To determine whether the genotype at these loci might influence susceptibility to the adverse effects of benzene exposure, 208 Bulgarian petrochemical workers and controls, whose exposure to benzene was determined by active personal sampling, were studied. The frequency of DNA single-strand breaks (DNA-SSB) was determined by alkaline elution, and genotype analysis was performed for five metabolic loci. Individuals c...

  3. A equipment for rapid detecting human nuclide aerosol concentration in high radon

    International Nuclear Information System (INIS)

    The aerosol concentration of radon and its daughter is high to 103-104 Bq/m3 under hole base, and especially nuclear equipment environments, it will affect the detection of human nuclide aerosol (for example U, Pu), even result in measure invalidation, which is a urgent problem to solve for many years. Now, we have researched and manufactured a new equipment for detect aerosol concentration. It can be used to detect human nuclide in high Radon aerosol concentration, And it also has a high sensitivity and a rapid detection velocity. This equipment can detect aerosol concentration rapidly and continuously in nuclear work location and gas vent. (authors)

  4. High-Efficiency Solar Thermal Vacuum Demonstration Completed for Refractive Secondary Concentrator

    Science.gov (United States)

    Wong, Wayne A.

    2001-01-01

    Common to many of the space applications that utilize solar thermal energy--such as electric power conversion, thermal propulsion, and furnaces--is a need for highly efficient, solar concentration systems. An effort is underway at the NASA Glenn Research Center to develop the refractive secondary concentrator, which uses refraction and total internal reflection to efficiently concentrate and direct solar energy. When used in combination with advanced lightweight primary concentrators, the refractive secondary concentrator enables very high system concentration ratios (10,000 to 1) and very high temperatures (>2000 K). The innovative refractive secondary concentrator offers significant advantages over all other types of secondary concentrators. The refractive secondary offers the highest throughput efficiency, provides for flux tailoring, requires no active cooling, relaxes the pointing and tracking requirements of the primary concentrator, and enables very high system concentration ratios. This technology has broad applicability to any system that requires the conversion of solar energy to heat. Glenn initiated the development of the refractive secondary concentrator in support of Shooting Star, a solar thermal propulsion flight experiment, and continued the development in support of Space Solar Power.

  5. Benzene and MTBE Sorption in Fine Grain Sediments

    Science.gov (United States)

    Leal-Bautista, R. M.; Lenczewski, M. E.

    2003-12-01

    The practice of adding methyl tert-butyl ether (MTBE) to gasoline started in the late 1970s and increased dramatically in the 1990s. MTBE first was added as a substitute for tetra-ethyl lead then later as a fuel oxygenate. Although the use of MTBE has resulted in significant reduction in air pollution, it has become a significant groundwater contaminant due to its high solubility in water, high environmental mobility, and low potential for biodegradation. A recent report (1999-2001) by the Metropolitan Water District of Southern California in collaboration with United State Geological Survey and the Oregon Health and Science University found that MTBE was the second most frequent detected volatile organic compound in groundwater. In Illinois, MTBE has been found in 26 of the 1,800 public water supplies. MTBE has also been blended in Mexico into two types of gasoline sold in the country by the state oil company (PEMEX) but is not monitored in groundwater at this time. Early research on MTBE considered it unable to adsorb to soils and sediments, however, by increasing the organic matter and decreasing the size of the grains (silts or clays) this may increase sorption. The objective of this study is to determine if fine grained materials have the potential for sorption of MTBE due to its high specific surface area (10-700 m 2/g) and potentially high organic matter (0.5-3.8%). The experiment consisted of sorption isotherms to glacial tills from DeKalb, Illinois and lacustrine clays from Chalco, Mexico. Experiments were performed with various concentrations of MTBE and benzene (10, 50, 100, 500 and 1000 ug/L) at 10° C and 25° C. Results showed a range of values for the distribution coefficient (Kd, linear model). At 10° C the Kd value for MTBE was 0.187 mL/g for lacustrine clay while the glacial loess had a value of 0.009 mL/g. The highest Kd values with MTBE were 0.2859 mL/g for organic rich lacustrine clays and 0.014 mL/g for glacial loess at 25° C. The highest values with benzene were 0.323 mL/g for organic rich lacustrine clays and 0.119 mL/g for glacial loess at 10° C. At 25° C the organic rich lacustrine clays the Kd value was 0.332 mL/g, while Kd value for glacial loess was 0.114 mL/g. Sands with no organic matter (Ottawa sand) had a value of < 0.001 mL/g for both temperatures 25° C and 10° C and both organic compounds. The retardation factor (R) for MTBE was 1.559 at 10° C and 1.855 at 25° C for lacustrine clays; while the glacial tills R was 1.058 at 10° C and 1.095 at 25° C. The retardation factor for benzene was 1.967 at 10° C and 1.996 at 25° C for lacustrine clays; while the glacial tills R was 1.039 at 10° C and 1.037 at 25° C. These results indicate higher retardation values than previously determined for a clayey sand; therefore show that sorption can occur in fine grain materials especially with high organic matter. This study contributes to the understanding of the sorption of MTBE and improves the knowledge to implement the optimal remediation method for sites contaminated by MTBE.

  6. Urinary 1-hydroxypyrene concentrations in coke oven workers

    OpenAIRE

    Wu, M. T.; Mao, I. F.; Ho, C. K.; Wypij, D.; Lu, P. L.; Smith, T. J.; Chen, M. L.; Christiani, D. C.

    1998-01-01

    OBJECTIVES: To investigate the relation of individual occupational exposure to total particulates benzene soluble fraction (BSF) of ambient air with urinary 1-hydroxypyrene (1-OHP) concentrations among coke oven workers in Taiwan. METHODS: 80 coke oven workers and 50 referents were monitored individually for the BSF of breathing zone air over three consecutive days. Exposures were categorised as high, medium, or low among coke oven workers based on exposure situations. The high exposure...

  7. Neutron scattering model for benzene

    International Nuclear Information System (INIS)

    A theoretical model analogous to the Nelkin model for water for neutron scattering by protons bound in benzene is proposed. The physical model comprises a free translator of mass 78, a hindered ratational oscillator of effective mass 21.3 at an energy of 0.02 eV and two vibrational oscillators at energies 0.146 and 0.38 eV with masses of 1.62 and 3.09 respectively. The diffusion constant of 51 000 cm2/sec calculated by the model agrees well with the experimental value of (50 360 +- 200) cm2/sec. (orig.)

  8. High catechin concentrations detected in Withania somnifera (ashwagandha by high performance liquid chromatography analysis

    Directory of Open Access Journals (Sweden)

    Sulaiman Siti

    2011-08-01

    Full Text Available Abstract Background Withania somnifera is an important medicinal plant traditionally used in the treatment of many diseases. The present study was carried out to characterize the phenolic acids, flavonoids and 1,1-diphenyl-2-picrylhydrazyl radical (DPPH scavenging activities in methanolic extracts of W. somnifera fruits, roots and leaves (WSFEt, WSREt and WSLEt. Methods WSFEt, WSREt and WSLEt was prepared by using 80% aqueous methanol and total polyphenols, flavonoids as well as DPPH radical scavenging activities were determined by spectrophotometric methods and phenolic acid profiles were determined by HPLC methods. Results High concentrations of both phenolics and flavonoids were detected in all parts of the plant with the former ranging between 17.80 ± 5.80 and 32.58 ± 3.16 mg/g (dry weight and the latter ranging between 15.49 ± 1.02 and 31.58 ± 5.07 mg/g. All of the three different plant parts showed strong DPPH radical scavenging activities (59.16 ± 1.20 to 91.84 ± 0.38%. Eight polyphenols (gallic, syringic, benzoic, p-coumaric and vanillic acids as well as catechin, kaempferol and naringenin have been identified by HPLC in parts of the plant as well. Among all the polyphenols, catechin was detected in the highest concentration (13.01 ± 8.93 to 30.61 ± 11.41 mg/g. Conclusion The results indicating that W. somnifera is a plant with strong therapeutic properties thus further supporting its traditional claims. All major parts of W. somnifera such as the roots, fruits and leaves provide potential benefits for human health because of its high content of polyphenols and antioxidant activities with the leaves containing the highest amounts of polyphenols specially catechin with strong antioxidant properties.

  9. Comparison of measurement methods for benzene and toluene

    Science.gov (United States)

    Wideqvist, U.; Vesely, V.; Johansson, C.; Potter, A.; Brorström-Lundén, E.; Sjöberg, K.; Jonsson, T.

    Diffusive sampling and active (pumped) sampling (tubes filled with Tenax TA or Carbopack B) were compared with an automatic BTX instrument (Chrompack, GC/FID) for measurements of benzene and toluene. The measurements were made during differing pollution levels and different weather conditions at a roof-top site and in a densely trafficked street canyon in Stockholm, Sweden. The BTX instrument was used as the reference method for comparison with the other methods. Considering all data the Perkin-Elmer diffusive samplers, containing Tenax TA and assuming a constant uptake rate of 0.406 cm3 min-1, showed about 30% higher benzene values compared to the BTX instrument. This discrepancy may be explained by a dose-dependent uptake rate with higher uptake rates at lower dose as suggested by laboratory experiments presented in the literature. After correction by applying the relationship between uptake rate and dose as suggested by Roche et al. (Atmos. Environ. 33 (1999) 1905), the two methods agreed almost perfectly. For toluene there was much better agreement between the two methods. No sign of a dose-dependent uptake could be seen. The mean concentrations and 95% confidence intervals of all toluene measurements (67 values) were (10.80±1.6) ?g m -3 for diffusive sampling and (11.3±1.6) ?g m -3 for the BTX instrument, respectively. The overall ratio between the concentrations obtained using diffusive sampling and the BTX instrument was 0.91±0.07 (95% confidence interval). Tenax TA was found to be equal to Carbopack B for measuring benzene and toluene in this concentration range, although it has been proposed not to be optimal for benzene. There was also good agreement between the active samplers and the BTX instrument.

  10. Anaerobic benzene oxidation by Geobacter species.

    Science.gov (United States)

    Zhang, Tian; Bain, Timothy S; Nevin, Kelly P; Barlett, Melissa A; Lovley, Derek R

    2012-12-01

    The abundance of Geobacter species in contaminated aquifers in which benzene is anaerobically degraded has led to the suggestion that some Geobacter species might be capable of anaerobic benzene degradation, but this has never been documented. A strain of Geobacter, designated strain Ben, was isolated from sediments from the Fe(III)-reducing zone of a petroleum-contaminated aquifer in which there was significant capacity for anaerobic benzene oxidation. Strain Ben grew in a medium with benzene as the sole electron donor and Fe(III) oxide as the sole electron acceptor. Furthermore, additional evaluation of Geobacter metallireducens demonstrated that it could also grow in benzene-Fe(III) medium. In both strain Ben and G. metallireducens the stoichiometry of benzene metabolism and Fe(III) reduction was consistent with the oxidation of benzene to carbon dioxide with Fe(III) serving as the sole electron acceptor. With benzene as the electron donor, and Fe(III) oxide (strain Ben) or Fe(III) citrate (G. metallireducens) as the electron acceptor, the cell yields of strain Ben and G. metallireducens were 3.2 × 10(9) and 8.4 × 10(9) cells/mmol of Fe(III) reduced, respectively. Strain Ben also oxidized benzene with anthraquinone-2,6-disulfonate (AQDS) as the sole electron acceptor with cell yields of 5.9 × 10(9) cells/mmol of AQDS reduced. Strain Ben serves as model organism for the study of anaerobic benzene metabolism in petroleum-contaminated aquifers, and G. metallireducens is the first anaerobic benzene-degrading organism that can be genetically manipulated. PMID:23001648

  11. Anaerobic Benzene Oxidation via Phenol in Geobacter metallireducens

    OpenAIRE

    Zhang, Tian; Tremblay, Pier-luc; Chaurasia, Akhilesh Kumar; Smith, Jessica A.; Bain, Timothy S.; Lovley, Derek R.

    2013-01-01

    Anaerobic activation of benzene is expected to represent a novel biochemistry of environmental significance. Therefore, benzene metabolism was investigated in Geobacter metallireducens, the only genetically tractable organism known to anaerobically degrade benzene. Trace amounts (

  12. 40 CFR 721.1210 - Benzene, (2-chloroethoxy)-.

    Science.gov (United States)

    2010-07-01

    ...2010-07-01 2010-07-01 false Benzene, (2-chloroethoxy)-. 721.1210...Specific Chemical Substances § 721.1210 Benzene, (2-chloroethoxy)-. (a) Chemical...The chemical substance identified as benzene, (2-chloroethoxy)- (PMN...

  13. Relationship between the oxidation potential of benzene metabolites and their inhibitory effect on DNA synthesis in L5178YS cells

    Energy Technology Data Exchange (ETDEWEB)

    Pellack-Walker, P.; Walker, J.K.; Evans, H.H.; Blumer, J.L.

    1985-12-01

    The effects of benzene and its metabolites on the rate of DNA synthesis were measured in the mouse lymphoma cell line, L5178YS. The direct toxicity of benzene could be distinguished from that of its metabolites since bioactivation of benzene in L5178YS cells was not observed. Cells were exposed to benzene, phenol, catechol, hydroquinone, p-benzoquinone, or 1,2,4-benzenetriol over the range of 1.0 X 10(-7) to 1.0 X 10(-2) M for 30 min, and the rate of DNA synthesis was measured at various times after chemical washout. Cell viability and protein synthesis were determined by trypan blue dye exclusion and (3H)leucine incorporation, respectively. Effects were designated as DNA specific when DNA synthesis was inhibited in the absence of discernible effects on cell membrane integrity and protein synthesis. Concentrations of benzene as high as 1 mM had no effect on DNA synthesis. Comparison of the effects at the maximum nontoxic dose for each compound showed that catechol and hydroquinone were the most effective, inhibiting DNA synthesis by 65%. Phenol, benzoquinone, and benzenetriol inhibited DNA synthesis by approximately 40%. Maximum inhibition was observed 60 min after metabolite washout in each case. Benzoquinone was the most potent inhibitor of DNA synthesis, followed by hydroquinone, benzenetriol, catechol, and phenol with ED50 values of 5 X 10(-6), 1 X 10(-5), 1.8 X 10(-4), 2.5 X 10(-4), and 8.0 X 10(-4), respectively. Cyclic voltammetric experiments were performed on the hydroxylated metabolites of benzene to assess the possible involvement of a redox-type mechanism in their inhibition of DNA synthesis. The ease of oxidation of these metabolites correlated with their ED50 values for inhibition of DNA synthesis (r = 0.997). This suggests that oxidation of phenol or one of its metabolites may be necessary for production of the species involved in inhibition of DNA synthesis.

  14. 46 CFR 30.25-3 - Benzene.

    Science.gov (United States)

    2010-10-01

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

  15. Rate constants for the reactions of benzene-chlorine atom ?-complexes with alcohols in carbon tetrachloride

    International Nuclear Information System (INIS)

    The reactivity and selectivity of benzene-chlorine atom ?-complexes for hydrogen atom abstraction from various alcohols were investigated. Benzene-chlorine atom ?-complexes were produced in liquid carbon tetrachloride using the technique of pulse radiolysis at room temperature. The effects of the concentration of benzene and absorbed doses on the formation and decay kinetics were examined and the equilibrium constant of the complex formation was estimated by computer simulation to be 1700 dm3 mol-1. The absolute rate constants of the reaction of the ?-complexes with various alcohols were measured. Partial reactivities for hydrogen abstraction were estimated based on the observed rate constants. The experimental rate constants could be explained as a sum of the partial reactivities of various types of C-H bonds. While the hydrogen abstraction rate constants were one order less than those of free chlorine atoms, higher tertiary/primary selectivities were observed for benzene-chlorine atom ?-complexes. (author)

  16. Estimation of trace amounts of benzene in solvent-extracted vegetable oils and oil seed cakes.

    Science.gov (United States)

    Masohan, A; Parsad, G; Khanna, M K; Chopra, S K; Rawat, B S; Garg, M O

    2000-09-01

    A new method is presented for the qualitative and quantitative estimation of trace amounts (up to 0.15 ppm) of benzene in crude as well as refined vegetable oils obtained by extraction with food grade hexane (FGH), and in the oil seed cakes left after extraction. The method involves the selection of two solvents; cyclohexanol, for thinning of viscous vegetable oil, and heptane, for azeotroping out trace benzene as a concentrate from the resulting mixture. Benzene is then estimated in the resulting azeotrope either by UV spectroscopy or by GC-MS subject to availability and cost effectiveness of the latter. Repeatability and reproducibility of the method is within 1-3% error. This method is suitable for estimating benzene in vegetable oils and oil seed cakes. PMID:11064941

  17. Consequences of limiting benzene content of motor gasoline

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, E.H.; Conrard, M.C.; Cremer, G.; Hancke, J.; De Roocker, A.; Roshier, M.J.S.; Sibra, P.; De Valois, A.A.; Wake, R.H.

    1983-12-01

    Current motor gasoline benzene levels, related legislation in Western Europe and the consequences of limiting the benzene content of gasoline are considered. The sources of benzene in gasoline are reviewed and the existing legislation on allowable levels is summarized. The benzene levels in current motor gasolines are surveyed and the causes of variations are analyzed. Means of reducing benzene contents, either by adjusting existing processing routes or by extracting benzene from gasoline blending components, are considered. The impact of benzene limitations on the production of motor gasolines are assessed in terms of the costs involved and the energy penalties incurred. Finally, the potential problem of the disposal of extracted benzene is discussed.

  18. Gastrointestinal development of dairy calves fed low- or high-starch concentrate at two milk allowances

    DEFF Research Database (Denmark)

    Kosiorowska, Anna Katarzyna; Puggaard, Liselotte

    2011-01-01

    The objective was to study the effect of type of concentrate with varying starch and fibre content on growth and gastrointestinal development in preweaned dairy calves. Thirty-two newborn Danish Holstein male calves were allocated to four treatment groups in eight blocks of four calves. An experimental low-starch, high-molasses, high-fibre (EXP) concentrate or a traditional high-starch (TRA) concentrate were fed either at a high (HIGH; 2 × 3.2 kg/day) or a low (LOW; 2 × 1.6 kg/day) whole milk allowance in a 2 × 2 factorial design. TRA contained 350 and EXP 107 g starch/kg dry matter (DM), whereas the NDF content was 136 and 296 g/kg DM, respectively. Metabolizable energy (ME) was 11.2 and 12.2 MJ ME/kg DM in EXP and TRA, respectively. All calves had free access to artificially dried grass hay (9.8 MJ ME/kg DM). Four calves were culled during the experiment. The calves were euthanized either at 38 (12 calves) or 56 days (16 calves) of age. Evaluated across both slaughter ages, there was no difference between TRA and EXP in concentrate and hay intake, rumen weight and papillation. EXP resulted in increased villi number in duodenum and jejunum compared with TRA. Concentrate intake and reticulo-rumen weight was higher for LOW compared with HIGH milk allowance, whereas live weight gain was 20% lower. The results show that a low-starch, high-molasses, high-fibre concentrate with 8% lower ME content tended to reduce daily gain compared with a traditional calf starter concentrate, but resulted in similar ruminal development in preweaned calves both on a high and a low milk allowance fed along with grass hay. Furthermore, the results suggest that the experimental concentrate stimulated intestinal villi growth over that of the traditional concentrate. Udgivelsesdato: 8. september

  19. Gastrointestinal development of dairy calves fed low- or high-starch concentrate at two milk allowances.

    Science.gov (United States)

    Kosiorowska, A; Puggaard, L; Hedemann, M S; Sehested, J; Jensen, S K; Kristensen, N B; Kuropka, P; Marycz, K; Vestergaard, M

    2011-02-01

    The objective was to study the effect of type of concentrate with varying starch and fibre content on growth and gastrointestinal development in preweaned dairy calves. Thirty-two newborn Danish Holstein male calves were allocated to four treatment groups in eight blocks of four calves. An experimental low-starch, high-molasses, high-fibre (EXP) concentrate or a traditional high-starch (TRA) concentrate were fed either at a high (HIGH; 2 × 3.2 kg/day) or a low (LOW; 2 × 1.6 kg/day) whole milk allowance in a 2 × 2 factorial design. TRA contained 350 and EXP 107 g starch/kg dry matter (DM), whereas the NDF content was 136 and 296 g/kg DM, respectively. Metabolizable energy (ME) was 11.2 and 12.2 MJ ME/kg DM in EXP and TRA, respectively. All calves had free access to artificially dried grass hay (9.8 MJ ME/kg DM). Four calves were culled during the experiment. The calves were euthanized either at 38 (12 calves) or 56 days (16 calves) of age. Evaluated across both slaughter ages, there was no difference between TRA and EXP in concentrate and hay intake, rumen weight and papillation. EXP resulted in increased villi number in duodenum and jejunum compared with TRA. Concentrate intake and reticulo-rumen weight was higher for LOW compared with HIGH milk allowance, whereas live weight gain was 20% lower. The results show that a low-starch, high-molasses, high-fibre concentrate with 8% lower ME content tended to reduce daily gain compared with a traditional calf starter concentrate, but resulted in similar ruminal development in preweaned calves both on a high and a low milk allowance fed along with grass hay. Furthermore, the results suggest that the experimental concentrate stimulated intestinal villi growth over that of the traditional concentrate. PMID:22440766

  20. High concentration suspended sediment measurments using acontinuous fiber optic in-stream transmissometer

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, Chris G.; Laycak, Danny T.; Hoppes, William; Tran,Nguyen T.; Shi, Frank G.

    2004-05-26

    Suspended sediment loads mobilized during high flow periods in rivers and streams are largely uncharacterized. In smaller and intermittent streams, a large storm may transport a majority of the annual sediment budget. Therefore monitoring techniques that can measure high suspended sediment concentrations at semi-continuous time intervals are needed. A Fiber optic In-stream Transmissometer (FIT) is presented for continuous measurement of high concentration suspended sediment in storm runoff. FIT performance and precision were demonstrated to be reasonably good for suspended sediment concentrations up to 10g/L. The FIT was compared to two commercially available turbidity devices and provided better precision and accuracy at both high and low concentrations. Both turbidity devices were unable to collect measurements at concentrations greater than 4 g/L. The FIT and turbidity measurements were sensitive to sediment particle size. Particle size dependence of transmittance and turbidity measurement poses the greatest problem for calibration to suspended sediment concentration. While the FIT was demonstrated to provide acceptable measurements of high suspended sediment concentrations, approaches to real-time suspended sediment detection need to address the particle size dependence in concentration measurements.

  1. Distribution of air pollutants in the Inn Valley atmosphere during high concentration events in winter 2006

    International Nuclear Information System (INIS)

    Full text: The goal of the INNOX field campaign, which took place during January and February 2006 near the town of Schwaz, was to obtain a three-dimensional picture of the spatial distribution of air pollutants in the Inn Valley during wintertime. For this purpose continuous ground based measurements and, on six chosen days, vertical profiles within the lowest 200 m above ground level (AGL) of the valley atmosphere of certain VOCs (benzene, toluene, etc.) and CO were performed using a proton-transfer-reaction mass spectrometry instrument (PTR-MS). For the soundings a 200-m long teflon line was fixed on a tethered balloon through which the air was sucked to the PTR-MS instrument and to a CO analyser. Next to the inlet on the tethered balloon meteorological data, such as air temperature, pressure, wind, were measured as well. Above the lowest 200 m AGL a research aircraft from MetAir AG (Switzerland), equipped with various instruments for in-situ measurements of air pollutants and meteorological data, was operated. A typical flight pattern consisted of five vertical cross sections between about 150 to 2500 m AGL and lasted about three hours. Altogether 25 hours of aircraft measurements were carried out on six different days. The combination of low-level balloon measurements and upper-level aircraft observations yields vertical profiles of various parameters which cover the whole valley atmosphere. Preliminary results which show strong vertical but also horizontal gradi strong vertical but also horizontal gradients of air pollutant concentrations will be presented. (author)

  2. Benzene leaks in sight; Benzeenlekken in het vizier

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-02-15

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

  3. Current collapse in tunneling transport through benzene

    CERN Document Server

    Hettler, M H; Wegewijs, M R; Schoeller, H

    2002-01-01

    We investigate the electrical transport through a system of benzene coupled to metal electrodes by electron tunneling. Using electronic structure calculations, a semi--quantitative model for the pi-electrons of the benzene is derived that includes general two-body interactions. After exact diagonalization of the benzene model the transport is computed using perturbation theory for weak electrode-benzene coupling (golden rule approximation). We include the effect of an applied electric field on the molecular states, as well as radiative relaxation. We predict a current collapse and strong negative differential conductance due to a ``blocking'' state when the electrode is coupled to the para-position of benzene. In contrast, for coupling to the meta-position, a series of steps in the I-V curve is found.

  4. High-integrated spectral splitting solar concentrator with double-light guide layers

    Science.gov (United States)

    Ma, Hongcai; Meng, Qingyu; Xu, Shuyan; Dong, Jihong; Li, Wei

    2014-10-01

    Individual secondary optical components in a spectral splitting solar concentrator utilizing a microlens array require multiple photovoltaic (PV) cells, which leads to the complexity of system alignment and a high cost. In order to improve the integration of the PV cells and thermal management, a spectral splitting concentrator coupled to double-light guide layers has been proposed. Using one-axis tracking, we further investigate the optical performance of the concentrator combined with a cylindrical microlens array with double vertically staggered light guide layers in detail. The results show that this solar concentrator maintains a good acceptance angle of ±2 deg in the east-west direction and an acceptable angle of ±14 deg in the perpendicular direction on both low and high spectrums, achieving a concentration ratio of 10×. Finally, the capability of lateral displacement tracking has been explored for an aperture angle of ±24 deg in this concentrator.

  5. Reducing Benzene and Cresol Levels in National Renewable Energy Laboratory's Pilot-Scale Biorefinergy Scrubber Water

    Energy Technology Data Exchange (ETDEWEB)

    Buzek, M.L.; Phillips, S.

    2004-01-01

    The Thermochemical Process Development Unit at the National Renewable Energy Laboratory converts biomass into energy by gasification or pyrolysis. The aqueous effluent generated in these processes must be disposed of as hazardous waste according to the Resource Conservation and Recovery Act because certain components exceed the regulatory concentration limit. Gas stripping of the scrubber water was investigated as a method of reducing benzene and cresol levels. A custom-designed packed-bed column was built and a half-factorial experimental design was implemented to determine the effects of gas flow rate, liquid flow rate, and column packing height on the final benzene concentration in the liquid. The experimental results show that packing height had a significant effect on final benzene concentration; gas flow rate and liquid flow rate had little effect. The effects of each design variable on final cresol concentration were not determined. Although the current column design did significantly reduce the benzene and cresol levels in the scrubber water, it did not reduce the concentrations below the regulatory limits. A full-factorial experimental design will be implemented with an increased packing height. Other variables, including column diameter and packing type, will be investigated to determine their effects on final benzene and cresol concentrations. Once the packed-bed column is determined to be effective in reducing contaminant concentrations below the regulatory limit, photocatalytic oxidation will be explored for remediating the benzene and cresol from the gas stream.

  6. Decreased insulin secretion and incretin concentrations and increased glucagon concentrations after a high-fat meal when compared with a high-fruit and -fiber meal.

    Science.gov (United States)

    Dandona, Paresh; Ghanim, Husam; Abuaysheh, Sanaa; Green, Kelly; Batra, Manav; Dhindsa, Sandeep; Makdissi, Antoine; Patel, Reema; Chaudhuri, Ajay

    2015-02-01

    This study was conducted to investigate whether a high-fat/high-carbohydrate (HFHC) meal induces an increase in plasma concentrations of glucagon, dipeptidyl peptidase-IV (DPP-IV), and CD26 expression in mononuclear cells (MNC) while reducing insulin, C-peptide, proinsulin, GIP, and GLP-1 concentrations. Ten healthy normal subjects were given either a 910-calorie HFHC meal or an American Heart Association (AHA) meal rich in fruit and fiber during the first visit and the other meal during the second visit in crossover design. Blood samples were collected at baseline and at 15, 30, 45, 60, 75, 90, 120, 180, and 300 min following the meal. There was a significantly greater increase in glucose concentrations and lower increase in postprandial insulin, C-peptide, and proinsulin concentrations and lower insulin/glucose ratios following the HFHC meal. HFHC meal intake induced marked increases in plasma glucagon and DPP-IV concentrations and an increase in CD26 mRNA expression in MNC compared with the AHA meal. In addition, the HFHC meal induced a reduction in GIP and peak GLP-1 secretion compared with the AHA meal. This was associated with a significantly greater increase in oxidative stress and proinflammatory mediators including, ROS generation, TNF?, and IL-1? mRNA expression and plasma concentrations of TBARS, FFA, and LPS. We conclude that the proinflammatory HFHC meals result in lower insulin, C-peptide, proinsulin, and GIP secretion in association with higher plasma glucagon and DPP-IV concentrations and CD26 expression in MNC compared with the AHA meal. PMID:25406260

  7. Anaerobic Benzene Degradation in Petroleum-Contaminated Aquifer Sediments after Inoculation with a Benzene-Oxidizing Enrichment

    OpenAIRE

    Weiner, Jonathan M.; Lovley, Derek R.

    1998-01-01

    Sediments from the sulfate-reduction zone of a petroleum-contaminated aquifer, in which benzene persisted, were inoculated with a benzene-oxidizing, sulfate-reducing enrichment from aquatic sediments. Benzene was degraded, with apparent growth of the benzene-degrading population over time. These results suggest that the lack of benzene degradation in the sulfate-reduction zones of some aquifers may result from the failure of the appropriate benzene-degrading sulfate reducers to colonize the a...

  8. High glucose concentrations partially release hexokinase from inhibition by glucose 6-phosphate.

    OpenAIRE

    Fujii, S.; Beutler, E.

    1985-01-01

    The phosphorylation of glucose by human erythrocyte hexokinase follows classical Michaelis-Menten kinetics; hexokinase manifests maximum activity at 5 mM glucose, and no further increase in activity can be measured at higher glucose concentrations. However, the erythrocytes of diabetics and normal erythrocytes incubated with high concentrations of glucose contain increased concentrations of glucose 6-phosphate. To elucidate the mechanism of accumulation of glucose 6-phosphate when erythrocyte...

  9. The effects of high soil CO2 concentrations on leaf reflectance of maize plants

    OpenAIRE

    Noomen, M. F.; Skidmore, A. K.

    2009-01-01

    Carbon dioxide gas at higher concentrations is known to kill vegetation and can also lead to asphyxiation in humans and animals. The objective of this study is to test whether soil CO2 concentrations ranging from 2% to 50% can be detected using vegetative spectral reflectance. A greenhouse experiment was performed to measure the reflectance of maize plants growing in soil contaminated with high concentrations of CO2. The correlation between leaf chlorophyll and reflectance in both the red edg...

  10. Volatilization of benzene and eight alkyl-substituted benzene compounds from water

    Science.gov (United States)

    Rathbun, R.E.; Tai, D.Y.

    1988-01-01

    Predicting the fate of organic compounds in streams and rivers often requires knowledge of the volatilization characteristics of the compounds. The reference-substance concept, involving laboratory-determined ratios of the liquid-film coefficients for volatilization of the organic compounds to the liquid-film coefficient for oxygen absorption, is used to predict liquid-film coefficients for streams and rivers. In the absence of experimental data, two procedures have been used for estimating these liquid-film coefficient ratios. These procedures, based on the molecular-diffusion coefficient and on the molecular weight, have been widely used but never extensively evaluated. Liquid-film coefficients for the volatilization of benzene and eight alkyl-substituted benzene compounds (toluene through n-octylbenzene) from water were measured in a constant-temperature, stirred water bath. Liquid-film coefficients for oxygen absorption were measured simultaneously. A range of water mixing conditions was used with a water temperature of 298.2 K. The ratios of the liquid-film coefficients for volatilization to the liquid-film coefficient for oxygen absorption for all of the organic compounds were independent of mixing conditions in the water. Experimental ratios ranged from 0.606 for benzene to 0.357 for n-octylbenzene. The molecular-diffusion-coefficient procedure accurately predicted the ratios for ethylbenzene through n-pentylbenzene with a power dependence of 0.566 on the molecular-diffusion coefficient, in agreement with published values. Predicted ratios for benzene and toluene were slightly larger than the experimental ratios. These differences were attributed to possible interactions between the molecules of these compounds and the water molecules and to benzene-benzene interactions that form dimers. Because these interactions also are likely to occur in natural waters, it was concluded that the experimental ratios are more correct than the predicted ratios for application purposes in the reference-substance concept. Predicted ratios for n-hexylbenzene, n-heptylbenzene, and n-octylbenzene were larger than the experimental ratios. These differences were attributed to a sorption-desorption process between these compounds and the surfaces of the constant-temperature water bath. Other experimental problems associated with preparing water solutions of these slightly soluble compounds also may have contributed to the differences. Because these processes are not part of the true volatilization process, it was concluded that the predicted ratios for these three compounds are probably more correct than the experimental ratios for application purposes in the reference-substance concept. Any model of the fate of these compounds in streams and rivers would have to include terms accounting for sorption processes, however. The molecular-weight procedure accurately predicted the ratios for ethylbenzene through n-pentylbenzene, but only if the power dependence on the molecular weight was decreased from the commonly used -0.500 to -0.427. Deviations for the low- and high-molecular-weight compounds were similar to those observed for the molecular-diffusion-coefficient procedure.

  11. Highly sensitive second-antibody enzyme immunoassay for determination of estradiol-17beta concentration in blood plasma of the mithun (Bos frontalis).

    Science.gov (United States)

    Mondal, Mohan; Prakash, Bukkaraya Samudram

    2007-04-01

    The objective of the present study was to develop and validate a simple, sensitive, quick and economic enzyme immunoassay (EIA) for estradiol-17beta (E2) in mithun (Bos frontalis) plasma on microtiter plates using a second-antibody coating technique and hormone-horseradish peroxidase as a label. For the assay, the wells of microtiter plates were coated with affinity-purified goat anti-rabbit IgG that binds the hormone-specific antibody. One milliliter of mithun plasma was extracted using benzene and 50 microl of 300 microl volume reconstituted with assay buffer was run in the assay along with standards ranging from 0.10-100 pg/well prepared in assay buffer. The sensitivity of the assay was 0.72 pg/ml. The intra- and inter-assay coefficients of variation were below 10%, and the extraction efficiency was >93%. Linearity of recovery of the added hormone concentrations was recorded. The assay developed was further validated biologically by estimating the hormone concentrations in six female and five male mithun calves, 12 cyclic mithuns for the entire reproductive cycle, and four pregnant mithun cows. The EIA developed can estimate low concentrations of E2 (2.2-5.2 pg/ml) in growing calves as well as very high concentrations of the hormone during pregnancy (E2=85.6-143.5 pg/ml). Apart from being non-radioactive, the assay developed has several advantages over conventional radioimmunoassays: it is more sensitive, less labor intensive, simpler to perform, and less time consuming. In conclusion, the EIA procedure described herein is sufficiently reliable, economic, safe, quick and sensitive to estimate the hormone at all physiological levels in bovine plasma. PMID:17867839

  12. Sub-Doppler Electronic Spectrum of the BENZENE-D2 Complex

    Science.gov (United States)

    Hayashi, Masato; Ohshima, Yasuhiro

    2014-06-01

    Excitation spectrum of the benzene-D2 van der Waals (vdW) complex in the vicinity of the S1 ? S0 601 vibronic transition of the monomer was recorded by utilizing mass-selective two-color resonance-enhanced two-photon ionization. Extensive adiabatic cooling with the rotational temperature of ?rb|<| 0.5 K was conducted by the high-pressure pulsed expansion, and sub-Doppler resolution yielding the line width of 250 MHz was realized in a collimated molecular beam by employing Fourier-transform-limited ultraviolet pulses for the excitation. In contrast to our previous study on the benzene-H2 complex, weaker binding ortho nuclear-spin isomer, correlating to the j = 0 state of a freely rotating D2, was observed in addition to the stronger binding para isomer (with j = 1), by using a gas sample of normal D2. Three and two vibronic bands involving vdW-mode excitation were observed for the para and ortho isomers, respectively. By comparing the present results with those of the benzene-H2 complex, we made unambiguous assignments on the vdW modes involved in each observed band, and obtained complete sets of vibrational frequencies of all the three vdW modes for the both H2 and D2 isotopomers in the S1 61 manifold. One of the vdW frequency correlates to the splitting between the m = 0 and ± 1 sublevels in the j = 1 state of a freely rotating H2/D2 molecule, and the potential barrier for the hindered internal rotation has been evaluated to be ca. 60 cm-1 from the values. Ratio of the vdW frequencies between the H2 and D2 species deviate significantly from the value for the harmonic vibration (i.e., ?{2} ? 1.4), indicating substantial anharmonic character of the vdW modes in the complex. M. Hayashi and Y. Ohshima, Chem. Phys. 419, 131-137 (2013). M. Hayashi and Y. Ohshima, J. Phys. Chem. A 117, 9819-9830 (2013).

  13. Highly time-resolved imaging of combustion and pyrolysis product concentrations in solid fuel combustion: NO formation in a burning cigarette.

    Science.gov (United States)

    Zimmermann, Ralf; Hertz-Schünemann, Romy; Ehlert, Sven; Liu, Chuan; McAdam, Kevin; Baker, Richard; Streibel, Thorsten

    2015-02-01

    The highly dynamic, heterogeneous combustion process within a burning cigarette was investigated by a miniaturized extractive sampling probe (microprobe) coupled to photoionization mass spectrometry using soft laser single photon ionization (SPI) for online real-time detection of molecular ions of combustion and pyrolysis products. Research cigarettes smoked by a smoking machine are used as a reproducible model system for solid-state biomass combustion, which up to now is not addressable by current combustion-diagnostic tools. By combining repetitively recorded online measurement sequences from different sampling locations in an imaging approach, highly time- and space-resolved quantitative distribution maps of, e.g., nitrogen monoxide, benzene, and oxygen concentrations were obtained at a near microscopic level. The obtained quantitative distribution maps represent a time-resolved, movie-like imaging of the respective compound's formation and destruction zones in the various combustion and pyrolysis regions of a cigarette during puffing. Furthermore, spatially resolved kinetic data were ascertainable. The here demonstrated methodology can also be applied to various heterogenic combustion/pyrolysis or reaction model systems, such as fossil- or biomass-fuel pellet combustion or to a positional resolved analysis of heterogenic catalytic reactions. PMID:25582882

  14. Ambient air benzene at background sites in China's most developed coastal regions: Exposure levels, source implications and health risks.

    Science.gov (United States)

    Zhang, Zhou; Wang, Xinming; Zhang, Yanli; Lü, Sujun; Huang, Zhonghui; Huang, Xinyu; Wang, Yuesi

    2015-04-01

    Benzene is a known human carcinogen causing leukemia, yet ambient air quality objectives for benzene are not available in China. The ambient benzene levels at four background sites in China's most developed coastal regions were measured from March 2012 to February 2013. The sites are: SYNECP, in the Northeast China Plain (NECP); YCNCP, in the North China Plain (NCP); THYRD, in the Yangtze River Delta (YRD) and DHPRD, in the Pearl River Delta (PRD). It was found that the mean annual benzene levels (578-1297ppt) at the background sites were alarmingly higher, especially when compared to those of 60-480pptv monitored in 28 cities in the United States. Wintertime benzene levels were significantly elevated at both sites (SYNECP and YCNCP) in northern China due to heating with coal/biofuels. Even at these background sites, the lifetime cancer risks of benzene (1.7-3.7E-05) all exceeded 1E-06 set by USEPA as acceptable for adults. At both sites in northern China, good correlations between benzene and CO or chloromethane, together with much lower toluene/benzene (T/B) ratios, suggested that benzene was largely related to coal combustion and biomass/biofuel burning. At the DHPRD site in the PRD, benzene revealed a highly significant correlation with methyl tert-butyl ether (MTBE), indicating that its source was predominantly from vehicle emissions. At the THYRD site in the YRD, higher T/B ratios and correlations between benzene and tetrachloroethylene, or MTBE, implied that benzene levels were probably affected by both traffic-related and industrial emissions. PMID:25618820

  15. Hydrogen isotope analysis of benzene and toluene emitted from vehicles

    Science.gov (United States)

    Kikuchi, Nami; Kawashima, Hiroto

    2013-06-01

    The isotopic analysis of atmospheric volatile organic compounds (VOCs), and in particular their hydrogen isotope ratio (?2H), has the potential to be an effective tool for clearly identifying sources of VOCs. However, to date there have been very few such analyzes. Here, we have analyzed the ?2H values of VOCs using thermal desorption and chromatography, thermal conversion, and isotope ratio mass spectrometry (TD-GC/TC/IRMS). After determining the analytical conditions needed for high precision and accurate analysis, we adopted minimum peak area thresholds of 10 Vs for the low concentration samples and 15 Vs for other samples. We also confirmed that breakthrough during adsorption of samples would have only minimal effect. We found that the collected samples could be stored for at least 7 days. Precisions of 1.1‰-5.3‰ (n = 7) were obtained for 28 standard compounds in a standard gas containing 58 VOCs (C6-C11). Next, we collected the exhaust gas produced in cold mode and hot mode from five vehicles, and measured the ?2H values. For benzene, we found that the ?2H value for the hot mode vehicle emissions was 19.3-104.7‰ lighter than that for the cold mode, while the ?2H value of the vaporized gasoline was 0.7-25.2‰ close to that in the cold mode. It should, therefore, be possible to distinguish cold mode vehicle emissions from those of the hot mode by analyzing the hydrogen isotope ratio. For benzene, particularly, the difference in ?2H values between 2 modes is important since emitted in large quantity from vehicles generally. Additionally, we measured VOCs in vaporized gasoline and roadside air, and compared the results with those for vehicle emissions. The roadside samples were characterized mainly by the hot mode. It has been shown that the hot mode has a significant impact on roadside VOCs, if no isotopic fractionation in the atmosphere is assumed. The results suggest that our approach could improve our understanding of the origin and fate of atmospheric VOCs, by allowing measurement of the ?2H values of further target compounds and sources.

  16. Secondary organic aerosol formation from the photo-oxidation of benzene

    Science.gov (United States)

    Borrás, Esther; Tortajada-Genaro, Luis Antonio

    2012-02-01

    The production of condensate compounds from the degradation of benzene by OH radical chemistry was studied. Secondary organic aerosol (SOA) formation was investigated in the EUPHORE ( European Photoreactor) simulation chambers. Experiments were performed under different OH-production conditions - addition of H 2O 2, NO or HONO -, in a high-volume reactor, with natural light and in the absence of seed aerosols. The consumption of precursor/reagents, the formation of gas-phase and particulate-phase products and the temporal evolution of aerosol were monitored. Several aerosol physical properties - mass concentration, overall aerosol yield, particle size distribution and density - were determined and found to be clearly dependent on OH radical production and NO x concentrations. Furthermore, the use of one and/or two products gas-particle partitioning absorption models allowed us to determine the aerosol yield curves. The SOA yield ranged from 1.6 to 9.7 %, with higher SOA formation under low-NO x conditions. Chemical characterization of the SOA was carried out, determining multi-oxygenated condensed organic compounds by a method based on the gas chromatography-mass spectrometry technique. Several ring-retaining and ring-cleavage products were identified and quantified. The compounds with the highest percentage contribution to the total aerosol mass were 4-nitrobenzene-1,2-diol, butenedioic acid, succinic acid and trans-trans-muconic. In addition, a multigenerational study was performed comparing with the photo-oxidations of phenol and catechol. The results showed that although the mass concentration of SOA produced was different, the physical and chemical properties were quite similar. Finally, we suggest a general mechanism to describe how changes in benzene degradation pathways - rate of OH generation and concentration of NO x - could justify the variation in SOA production and properties.

  17. Effective surface dilatational viscosity of highly concentrated particle-laden interfaces

    OpenAIRE

    Lishchuk, S. V.

    2014-01-01

    The effective surface dilatational viscosity is calculated of a flat interface separating two immiscible fluids laden with half-immersed monodisperse rigid spherical non-Brownian particles in the limit of high particle concentration. The derivation is based upon the facts that (i) highly-concentrated particle arrays in a plane form hexagonal structure, and (ii) the dominant contribution to the viscous dissipation rate arises in the thin gaps between neighboring particles.

  18. Ultra-high concentration effects in multi-junction solar cells

    Science.gov (United States)

    Katz, Eugene A.; Gordon, Jeffrey M.; Tassew, Wondesen; Feuermann, Daniel

    2005-08-01

    We report results of ultra-high-flux experiments on tandem and triple-junction solar cells, with a real-sun probe predicated on mini-dish fiber-optic concentrators. We focus on the sensitivity of cell efficiency to a wide range of flux levels and distributions. Our experiments also revealed pronounced reversible photovoltaic hysteresis at high concentration, and provide a non-destructive method for assessing tunnel diode characteristics.

  19. Effective surface dilatational viscosity of highly concentrated particle-laden interfaces.

    Science.gov (United States)

    Lishchuk, S V

    2014-11-01

    The effective surface dilatational viscosity is calculated of a flat interface separating two immiscible fluids laden with half-immersed monodisperse rigid spherical non-Brownian particles in the limit of high particle concentration. The derivation is based upon the facts that (i) highly concentrated particle arrays in a plane form a hexagonal structure and (ii) the dominant contribution to the viscous dissipation rate arises in the thin gaps between neighboring particles. PMID:25493879

  20. Transcriptional analysis of adaptation to high glucose concentrations in Zymomonas mobilis.

    Science.gov (United States)

    Zhang, Kun; Shao, Huanhuan; Cao, Qinghua; He, Ming-Xiong; Wu, Bo; Feng, Hong

    2015-02-01

    The ethanologenic bacterium Zymomonas mobilis is usually tolerant to high concentrations of glucose. The addition of sorbitol decreases the lag phase and increases ethanol yield and productivity of the bacteria in high glucose concentrations. The molecular mechanisms of adaptation to high glucose concentrations and the effect of sorbitol are still unclear. In this study, microarray analysis was used to study the global transcriptional adaptation responses of Z. mobilis to high glucose concentrations. A total of 235 genes were differentially expressed when 220 g/L glucose was added with or without 10 mM sorbitol. These genes are involved in diverse aspects of cell metabolism and regulation, including membrane transporters, nitrogen metabolism, and plasmid-encoded genes. However, most differentially expressed genes were downregulated when sorbitol was added. Notably, the transcription of almost all genes involved in the Entner-Doudoroff and ethanol production pathways was not significantly affected. In addition, a prophage and a nitrogen-fixation cluster were significantly induced. These results revealed that Z. mobilis cells responded to high glucose concentrations by regulating the transcriptional levels of genes related to membrane channels and transporters, stress response mechanisms, and metabolic pathways. These data provide insight into the intracellular adaptation responses to high glucose concentrations and reveal strategies to engineer efficient ethanol fermentation in Z. mobilis. PMID:25582559

  1. Apparent Benzene Solubility in Tetraphenylborate Slurries

    International Nuclear Information System (INIS)

    Personnel conducted testing to determine the apparent solubility of benzene in potassium tetraphenylborate (KTPB) slurries. The lack of benzene vapor pressure suppression in these tests indicate that for a 6.5 wt percent solids KTPB slurry in 4.65 M Na+ salt solution at approximately 25 degrees Celsius, no significant difference exists between the solubility of benzene in the slurry and the solubility of benzene in salt solution without KTPB solids. The work showed similar results in slurry with 6,000 mg/L sludge and 2,000 mg/L monosodium titanate added. Slurries containing tetraphenylborate decomposition intermediates (i.e., 4,200 mg/L triphenylboron (3PB), 510 mg/L diphenylborinic acid (2PB) and 1,500 mg/L phenylboric acid (1PB) or 100 mg/L tri-n-butylphosphate (TBP)) also showed no significant difference in benzene solubility form filtrate containing no KTPB solids. Slurry containing 2,000 mg/L Surfynol 420 did exhibit significant additional benzene solubility, as did irradiated slurries. The vapor pressure depression in the irradiated slurries presumably results from dissolution of biphenyl and other tetraphenylborate irradiation products in the benzene

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

    International Nuclear Information System (INIS)

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

  3. Pressure-induced oligomerization of benzene at room temperature as a precursory reaction of amorphization.

    Science.gov (United States)

    Shinozaki, Ayako; Mimura, Koichi; Kagi, Hiroyuki; Komatu, Kazuki; Noguchi, Naoki; Gotou, Hirotada

    2014-08-28

    Oligomerization of benzene at high pressures up to 16 GPa was investigated at room temperature using an opposed-anvil type pressure apparatus. The recovered samples were analyzed using GC-MS to identify and quantify the products after the high-pressure experiments. Some structural isomers of benzene dimer as well as biphenyl, naphthalene, and terphenyl isomers were detected at pressures higher than 13 GPa. The molar yield of the polycyclic aromatic hydrocarbons increased concomitantly with increasing pressure, although benzene still remained. The oligomerization is likely to occur when the neighbor distance of the benzene molecules exceeds the threshold of the reaction distance. The oligomerization is regarded as a precursory phenomenon of the amorphization that occurs at higher pressure. PMID:25173013

  4. Combustion of hydrogen at high concentrations including the effect of obstacles

    International Nuclear Information System (INIS)

    Combustion of hydrogen-steam-air mixtures has been studied in a 2.3-m diameter sphere at 1000C and near atmospheric pressure. The range of concentrations investigated were 10% to 42% hydrogen and 0% to 30% steam by volume. Over this range, the combustion proceeded until one of the reactants was completely consumed. Measured peak combustion pressures were 10 to 20% below the calculated, adiabatic values. the effect of fan-generated turbulence was less pronounced at high hydrogen concentrations than at low concentrations. The effect of obstacles was investigated by placing gratings in the sphere. Although gratings increased the extent of combustion and the peak pressure at low concentrations, their effect was less at high hydrogen concentrations. In general, gratings acted as heat sinks, reducing, in some cases, the peak pressure as well as the rate of pressure rise. These observations are preliminary and further studies are required for confirmation

  5. Preparation of a high concentration of lithium-7 atoms in a magneto-optical trap

    International Nuclear Information System (INIS)

    This study is aimed at obtaining high concentration of optically cooled lithium-7 atoms for preparing strongly interacting ultracold plasma and Rydberg matter. A special setup has been constructed, in which two high-power semiconductor lasers are used to cool lithium-7 atoms in a magneto-optical trap. At an optimum detuning of the cooling laser frequency and a magnetic field gradient of 35 G/cm, the concentration of ultracold lithium-7 atoms reaches about 1011 cm?3. Additional independent information about the concentration and number of ultracold lithium-7 atoms on different sublevels of the ground state was obtained by using of an additional probing laser

  6. Probing concentrator solar cell performance at high flux with localized irradiation

    Science.gov (United States)

    Katz, Eugene A.; Gordon, Jeffrey M.; Tassew, Wondesen; Feuermann, Daniel

    2006-08-01

    The macroscopic parameters that characterize photovoltaic (PV) performance, including their spatial dependence, especially at high flux, are determined with extensive localized solar measurements on high-efficiency concentrator solar cells. We present two studies that explore (a) the impact of nonuniform flux distribution on PV behavior, (b) how PV parameters vary across the cell surface (of particular interest in many high-concentration optical systems) and (c) the sensitivity of PV parameters to the spatial variation of series resistance R s that stems from irregular cell metallization. In so doing, we identify current-voltage trends unique to strongly inhomogeneous illumination and to R s losses at high flux.

  7. Experimental density, viscosity, interfacial tension and water solubility of ethyl benzene-?-methyl benzyl alcohol–water system

    International Nuclear Information System (INIS)

    Highlights: • Properties were measured for MBA (methyl benzyl alcohol)-EB (ethyl benzene)-water. • MBA concentration was found to influence all the properties strongly. • The water solubility, density, and viscosity increased at high MBA concentration. • The interfacial tension decreased sharply at high MBA concentration. • MBA dictates the phase separation and mass transfer of the ternary system. -- Abstract: Density, viscosity, interfacial tension, and water solubility were measured for the (?-methyl benzyl alcohol (MBA) + Ethyl benzene (EB)) system at different concentrations of MBA in contact with water and sodium hydroxide solution (0.01 mol · kg?1) as aqueous phases. The properties were measured to identify the component which plays a governing role in changing the physical properties relevant to mass transfer and phase separation of the ternary system. The concentration of MBA was found to be the major factor influencing all the properties. The water solubility, the density, and the viscosity increased notably at higher concentrations of MBA; while, the interfacial tension decreased strongly. The use of 0.01 mol · kg?1 NaOH as an aqueous phase resulted in a decrease of the interfacial tension and a minor decrease in the water solubility. The density data were correlated using a quadratic mixing rule to describe the influence of concentration at any temperature. The viscosity data are correlated using the Nissan and Grunberg and Katti-Chaudhri equations. The Szyzkowski’s equation was used to correlate the interfacial tension data. The water solubility data were described using an exponential relationship. All the correlations described the experimental physical property data adequately

  8. Studies on the mechanism of benzene toxicity

    Energy Technology Data Exchange (ETDEWEB)

    Snyder, R.; Dimitriadis, E.; Guy, R.; Hu, P.; Cooper, K.; Bauer, H.; Witz, G.; Goldstein, B.D. (Rutgers, State Univ. of New Jersey, Piscataway (USA))

    1989-07-01

    Using the 59Fe uptake method of Lee et al. it was shown that erythropoiesis in female mice was inhibited following IP administration of benzene, hydroquinone, p-benzoquinone, and muconaldehyde. Toluene protected against the effects of benzene. Coadministration of phenol plus either hydroquinone or catechol resulted in greatly increased toxicity. The combination of metabolites most effective in reducing iron uptake was hydroquinone plus muconaldehyde. We have also shown that treating animals with benzene leads to the formation of adducts of bone marrow DNA as measured by the 32P-postlabeling technique.

  9. Studies on the mechanism of benzene toxicity

    International Nuclear Information System (INIS)

    Using the 59Fe uptake method of Lee et al. it was shown that erythropoiesis in female mice was inhibited following IP administration of benzene, hydroquinone, p-benzoquinone, and muconaldehyde. Toluene protected against the effects of benzene. Coadministration of phenol plus either hydroquinone or catechol resulted in greatly increased toxicity. The combination of metabolites most effective in reducing iron uptake was hydroquinone plus muconaldehyde. We have also shown that treating animals with benzene leads to the formation of adducts of bone marrow DNA as measured by the 32P-postlabeling technique

  10. Simple and complex disorder in binary mixtures with benzene as a common solvent.

    Science.gov (United States)

    Požar, Martina; Seguier, Jean-Baptiste; Guerche, Jonas; Mazighi, Redha; Zorani?, Larisa; Mijakovi?, Marijana; Keži?-Lovrin?evi?, Bernarda; Sokoli?, Franjo; Perera, Aurélien

    2015-04-01

    Substituting benzene for water in computer simulations of binary mixtures allows one to study the various forms of disorder, without the complications often encountered in aqueous mixtures. In particular, we study the relationship between the local order generated by different types of molecular interactions and the nature of the global disorder, by analyzing the relationship between the concentration fluctuations and the correlation functions and the associated structure factors. Alkane-benzene mixtures are very close to ideal mixtures, despite appreciable short range shape mismatch interactions, acetone-benzene mixtures appear as a good example of regular mixtures, and ethanol-benzene mixtures show large micro-segregation. In the latter case, we can unambiguously demonstrate, unlike in the case of water, the appearance of domain-domain correlations, both in the correlation functions and the structure factor calculated in computer simulations. This finding helps to confirm the existence of a pre-peak in the structure factor associated with the micro-heterogeneity, which was speculated from several of our previous simulations of aqueous-alcohol mixtures. The fact that benzene as a solvent allows us to solve some of the problems that could not be solved with water points towards some of the particularities of water as a solvent, which we discuss herein. The concept of molecular emulsion put forward in our earlier work is useful in formulating these differences between water and benzene through the analogy with direct and inverse micellar aggregates. PMID:25777144

  11. A method for incorporating biodegradation rates of benzene into the risk assessment process

    International Nuclear Information System (INIS)

    Risk Assessment has been used extensively in developing health-based remedial criteria for sites with soils and groundwater impacted by petroleum products. In most cases of gasoline releases, benzene, a Group A carcinogen, is the focus of the evaluation. Therefore, this discussion will primarily involve the risk assessment of benzene. In modeling these long-term exposures, risk assessors often assume that the exposure point concentration of benzene remains constant. However, data from several studies indicate that biodegradation is a significant fate mechanism for benzene and other hydrocarbons. In this paper in order to justify the use of degradation estimates in the risk assessment of benzene, a brief summary of studies on the degradation of benzene in oils and groundwater is presented. This will be followed by a discussion of factors which should be considered in the selection of a degradation rate, and a discussion of the application of degradation rates into the estimation of risk and the development of ISCs. In addition, a case study is presented which provides an example of the application of the ISC methodology and illustrates its adaptability to site specific conditions and information requirements

  12. Treatment of co-mingled benzene, toluene and TCE in groundwater.

    Science.gov (United States)

    Chen, Liang; Liu, Yulong; Liu, Fei; Jin, Song

    2014-06-30

    This work addressed a hypothetical but practical scenario that includes biological oxidation and reductive dechlorination in treating groundwater containing co-mingled plume of trichloroethene (TCE), benzene and toluene. Groundwater immediately downgradient from the commonly used zero-valent iron (ZVI) has shown alkaline pH (up to 10.7). The elevated pH may influence BTEX compounds (i.e., benzene, toluene, ethyl benzene, and xylenes) biodegradation, which could also be inhibited by elevated concentrations of TCE. Data from this work suggests that the inhibition coefficients (IC) value for 100 ?g/L and 500 ?g/L of TCE on benzene and toluene degradation are 2.1-2.8 at pH 7.9, and 3.5-6.1 at pH 10.5. For a co-mingled plume, it appears to be more effective to reduce TCE by ZVI before addressing benzene and toluene biodegradation. The ample buffering capacity of most groundwater and the adaptation of benzene and toluene-degrading microbes are likely able to eliminate the adverse influence of pH shifts downgradient from a ZVI-PRB. PMID:24857895

  13. A High-Efficiency Refractive Secondary Solar Concentrator for High Temperature Solar Thermal Applications

    Science.gov (United States)

    Piszczor, Michael F., Jr.; Macosko, Robert P.

    2000-01-01

    A refractive secondary solar concentrator is a non-imaging optical device that accepts focused solar energy from a primary concentrator and redirects that light, by means of refraction and total internal reflection (TIR) into a cavity where the solar energy is used for power and/or propulsion applications. This concept offers a variety of advantages compared to typical reflective secondary concentrators (or the use of no secondary at all): higher optical efficiency, minimal secondary cooling requirements, a smaller cavity aperture, a reduction of outgassing from the cavity and flux tailoring of the solar energy within the heat receiver. During the past 2 years, NASA Lewis has been aggressively developing this concept in support of the NASA Marshall Shooting Star Flight Experiment. This paper provides a brief overview of the advantages and technical challenges associated with the development of a refractive secondary concentrator and the fabrication of a working unit in support of the flight demonstration program.

  14. Charge Transfer Complex Role in the Formation of Chlorobenzene in the ?-Irradiated Carbon Tetrachloride - Benzene System

    International Nuclear Information System (INIS)

    The formation of carbon tetrachloride-benzene charge transfer complex was confirmed by UV and NMR spectrometric studies. A change in UV spectrum of benzene is observed upon addition of carbon tetrachloride. The appearance of new bands supports the formation of charge transfer complex. NMR study shows that benzene proton chemical shift depends on the CCI4-C6H6 molar ratio. This observation is another criterion for the formation of benzene - carbon tetrachloride charge transfer complex. Job's Continuous Variation method indicates that a 2:1 CCI4-C6H6 charge transfer complex(2:1 CTC) could be formed. The association constants (K2:1) of this 2:1 CTC was found to be 0.0197 M-2 .The maximum concentration of 2:1 CTC was found at about 33% benzene mole percent. The maximum yield of chlorobenzene was obtained, also, upon radiolysis of CCI4-C6H6 samples at 2:1 molar ratio (33% benzene mole percent). Therefore, it could be concluded that 2:1 CTC participates in thc formation of chlorobenzene upon radiolysis of benzene - carbon tetrachloride system.This conclusion was supported by the dependence of the chlorobenzene yield of ?-irradiated 2: 1 carbon tetrachloride - benzene system on irradiation time according to third order kinetic equation with a very good linearity (R2 = 0.9977). Accordingly, the rate constant for the chlorobenzene formation underant for the chlorobenzene formation under this condition, was found to be ? 5.5 x 10-7 L2 .moI-2.h-1. We propose a radiation chemical mechanism in which the 2: 1 CTC plays a role in the formation of chlorobenzene

  15. Measurement of DNA repair deficiency in workers exposed to benzene

    International Nuclear Information System (INIS)

    We hypothesize that chronic exposure to environmental toxicants can induce genetic damage causing DNA repair deficiencies and leading to the postulated mutator phenotype of carcinogenesis. To test our hypothesis, a host cell reactivation (HCR) assay was used in which pCMVcat plasmids were damaged with UV light (175, 350 J/m2 UV light), inactivating the chloramphenicol acetyltransferase reporter gene, and then transfected into lymphocytes. Transfected lymphocytes were therefore challenged to repair the damaged plasmids, reactivating the reporter gene. Xeroderma pigmentosum (XP) and Gaucher cell lines were used as positive and negative controls for the HCR assay. The Gaucher cell line repaired normally but XP cell lines demonstrated lower repair activity. Additionally, the repair activity of the XP heterozygous cell line showed intermediate repair compared to the homozygous XP and Gaucher cells. We used HCR to measure the effects of benzene exposure on 12 exposed and 8 nonexposed workers from a local benzene plant. Plasmids 175 J/m2 and 350 J/m2 were repaired with a mean frequency of 66% and 58%, respectively, in control workers compared to 71% and 62% in exposed workers. Conversely, more of the exposed workers were grouped into the reduced repair category than controls. These differences in repair capacity between exposed and control workers were, however, not statistically significant. The lack of significant differences between the ex of significant differences between the exposed and control groups may be due to extremely low exposure to benzene (<0.3 ppm), small population size, or a lack of benzene genotoxicity at these concentrations. These results are consistent with a parallel hprt gene mutation assay. 26 refs., 4 figs., 2 tabs

  16. Ion-selective uranyl electrode with membrane based on a mixture of uranyl di-2-ethylhexylphosphate with tributlyphosphate in benzene

    Energy Technology Data Exchange (ETDEWEB)

    Serebrennikova, N.V.; Kukushkina, I.I.; Plotnikova, N.V.

    1982-04-01

    A study is presented of the electrochemical properties of an uranyl electrode with a liquid membrane, a benzene solution of UO/sub 2/R/sub 2/ mixed with tributylphosphate (TBP). The electrochemical properties of the electrode were studied using a TR-1501 electrometer with EZ-7 strip-chart recorder to record the transmembrane potential difference as a function of uranyl ion activity in aqueous sulfate solutions. The selectivity coefficients were determined by the method of bionic potentials for the electrode with various concentrations of uranyl di-2-ethylhexylphosphate and with various additives of TBP. As the UO/sub 2/R/sub 2/ concentration is changed the selective properties change with respect to a number of singly and doubly charged ions. The uranyl membrane electrode is more highly selective in the presence of a number of ions and has a lower boundary of uranyl ion content determination than electrodes with the membrane containing only uranyl di-2-ethylhexylphosphate in benzene. The properties of the electrode depend both on the concentration of ion exchange substance and on the quantity of tributylphosphate added.

  17. Deuterium isotope effect in 1H chemical shift of benzene-d1

    International Nuclear Information System (INIS)

    90 MHz 1H-NMR spectrum of liquid benzene-d1 has been measured and completely analysed as an AB2C2X (X = D, I = 1) system. The deuterium isotopic shifts relative to internal benzene, ?sub(A) = -1.4 ppb, ?sub(B) = -1.3 ppb and ?sub(C) = +0.3 ppb, have been determined. (author)

  18. Molecular engineering of push-pull porphyrin dyes for highly efficient dye-sensitized solar cells: the role of benzene spacers.

    Science.gov (United States)

    Yella, Aswani; Mai, Chi-Lun; Zakeeruddin, Shaik M; Chang, Shu-Nung; Hsieh, Chi-Hung; Yeh, Chen-Yu; Grätzel, Michael

    2014-03-10

    Porphyrins have drawn much attention as sensitizers owing to the large absorption coefficients of their Soret and Q?bands in the visible region. In a donor and acceptor zinc porphyrin we applied a new strategy of introducing 2,1,3-benzothiadiazole (BTD) as a ?-conjugated linker between the anchoring group and the porphyrin chromophore to broaden the absorption spectra to fill the valley between the Soret and Q?bands. With this novel approach, we observed 12.75% power-conversion efficiency under simulated one-sun illumination (AM1.5G, 100?mW?cm(-2)). In this study, we showed the importance of introducing the phenyl group as a spacer between the BTD and the zinc porphyrin in achieving high power-conversion efficiencies. Time-resolved fluorescence, transient-photocurrent-decay, and transient-photovoltage-decay measurements were employed to determine the electron-injection dynamics and the lifetime of the photogenerated charge carriers. PMID:24501108

  19. Concentrating and spectrum splitting optical device in high efficiency CPV module with five bandgaps

    Science.gov (United States)

    Taudien, Jerker Y.; Kern, Ludwig A.

    2013-09-01

    There is a need for a high efficiency low cost solar energy conversion system. Currently, most concentrating photovoltaic (CPV) systems concentrate the solar spectrum onto triple junction cells to strive for high conversion efficiencies and low cost. Other approaches to high efficiency use spectrum splitting. Triple junction systems are limited in efficiency and spectrum splitting systems are usually too costly for mass production. The objective is to design a spectrum splitting solar concentrator, using reverse ray tracing methods, to overcome the efficiency and cost limitations of current systems by using a single low cost optical device to concentrate and split the solar spectrum onto a large number of target photovoltaic (PV) cells. Dispersive properties of standard optical materials, such as glass or plastic, are utilized to achieve the desired spectral separation. Reverse ray tracing is used to simultaneously optimize the shape of the top and bottom interfaces of the solar concentrator to achieve the desired split spectrum at the target PV cells. Additional strategies to increase system efficiency and minimize optical losses, including draft surface shading and corner rounding losses, are explored. A CPV module, including the spectrum splitting solar concentrator and five PV cells of different bandgaps, is proposed. This spectrum splitting CPV system has a calculated aggregate cell conversion efficiency that exceeds 45%, has the potential to be mass produced, and meets the need for a high efficiency low cost solar energy conversion system.

  20. Nanoscale Analyses of High-Nickel Concentration Martensitic High-Strength Steels

    Science.gov (United States)

    Isheim, Dieter; Hunter, Allen H.; Zhang, Xian J.; Seidman, David N.

    2013-07-01

    Austenite reversion in martensitic steels is known to improve fracture toughness. This research focuses on characterizing mechanical properties and the microstructure of low-carbon, high-nickel steels containing 4.5 and 10 wt pct Ni after a QLT-type austenite reversion heat treatment: first, martensite is formed by quenching ( Q) from a temperature in the single-phase austenite field, then austenite is precipitated by annealing in the upper part of the intercritical region in a lamellarization step ( L), followed by a tempering ( T) step at lower temperatures. For the 10 wt pct Ni steel, the tensile strength after the QLT heat treatment is 910 MPa (132 ksi) at 293 K (20 °C), and the Charpy V-notch impact toughness is 144 J (106 ft-lb) at 188.8 K (-84.4 °C, -120 °F). For the 4.5 wt pct Ni steel, the tensile strength is 731 MPa (106 ksi) at 293 K (20 °C) and the impact toughness is 209 J (154 ft-lb) at 188.8 K (-84.4 °C, -120 °F). Light optical microscopy, scanning electron and transmission electron microscopies, synchrotron X-ray diffraction, and local-electrode atom-probe tomography (APT) are utilized to determine the morphologies, volume fractions, and local chemical compositions of the precipitated phases with sub-nanometer spatial resolution. The austenite lamellae are up to 200 nm in thickness, and up to several micrometers in length. In addition to the expected partitioning of Ni to austenite, APT reveals a substantial segregation of Ni at the austenite/martensite interface with concentration maxima of 10 and 23 wt pct Ni for the austenite lamellae in the 4.5 and 10 wt pct Ni steels, respectively. Copper-rich and M2C-type metal carbide precipitates were detected both at the austenite/martensite interface and within the bulk of the austenite lamellae. Thermodynamic phase stability, equilibrium compositions, and volume fractions are discussed in the context of Thermo-Calc calculations.

  1. Developmental toxicity and brain aromatase induction by high genistein concentrations in zebrafish embryos

    OpenAIRE

    Kim, Dong-jae; Seok, Seung-hyeok; Baek, Min-won; Lee, Hui-young; Na, Yi-rang; Park, Sung-hoon; Lee, Hyun-kyoung; Dutta, Noton Kumar; Kawakami, Koichi; Park, Jae-hak

    2009-01-01

    Genistein is a phytoestrogen found at a high level in soybeans. In vitro and in vivo studies showed that high concentrations of genistein caused toxic effects. This study was designed to test the feasibility of zebrafish embryos for evaluating developmental toxicity and estrogenic potential of high genistein concentrations. The zebrafish embryos at 24 h post-fertilization were exposed to genistein (1 × 10?4 M, 0.5 × 10?4 M, 0.25 × 10?4 M) or vehicle (ethanol, 0.1%) for 60 h. Genistei...

  2. The inorganic analogues of carbo-benzene

    Science.gov (United States)

    Jalife, Said; Audiffred, Martha; Islas, Rafael; Escalante, Sigfrido; Pan, Sudip; Chattaraj, Pratim K.; Merino, Gabriel

    2014-08-01

    Inspired by carbo-benzene, we have analyzed in silico the stability of carbo-borazine (C12B3N3H6) and the iminobora-mer of borazine (B9N9H6). Both systems may be regarded as the inorganic analogues of carbo-benzene, being B9N9H6 the perfect case. Unlike aromatic carbo-benzene, C12B3N3H6 and B9N9H6 can be classified as almost nonaromatic systems as indicated by the computed induced magnetic field. All these systems undergo dimerization very readily; therefore, they cannot be synthesized as such. However, akin to substituted carbo-benzene, the substitution of the hydrogen atom of C12B3N3H6 and B9N9H6 by other groups could stabilize them.

  3. Electromers of the benzene dimer radical cation.

    Science.gov (United States)

    B?och-Mechkour, Anna; Bally, Thomas

    2015-04-01

    The well-studied benzene dimer radical cation, which is prototypical for this class of species, has been reinvestigated computationally. Thereby it turned out that both the ?-hemibonded and the half-shifted sandwich structures of the benzene dimer cation, which had been independently proposed, represent stationary points on the B2PLYP-D potential energy surfaces. However, these structures belong to distinct electronic states, both of which are associated with potential surfaces that are very flat with regard to rotation of the two benzene rings in an opposite sense relative to each other. The surfaces of these two "electromers" of the benzene dimer cation are separated by only 3-4 kcal mol(-1) and do not intersect along the rotation coordinate, which represents a rather unique electronic structure situation. When moving on either of the two surfaces the title complex is an extremely fluxional species, in spite of its being bound by over 20 kcal mol(-1). PMID:25804703

  4. Potassium 2-iodo-benzene-sulfonate monohydrate.

    Science.gov (United States)

    Arshad, Muhammad Nadeem; Khan, Islam Ullah; Ahmad, Saeed; Shafiq, Muhammad; Stoeckli-Evans, Helen

    2008-01-01

    In the crystal structure of the title compound, K(+)·C(6)H(4)IO(3)S(-)·H(2)O, the potasium cation is 2.693?(3)-2.933?(3)?Å from the sulfonate and water O atoms (including symmetry-related atoms) and forms a two-dimensional sheet-like structure in the bc plane, with the iodo-benzene rings protruding above and below. The water mol-ecule of crystallization is hydrogen-bonded to sulfonate O atoms within this two-dimensional arrangement. Symmetry-related iodo-benzene rings are arranged perpendicular to one another with the I atom ca 4.1?Å from the centroid of the neighbouring benzene ring. In the crystal structure, these two-dimensional sheet-like supramolecular structures are arranged parallel to one another, stacked along the a-axis direction, with the benzene rings inter-digitated. PMID:21203089

  5. Recommended sublimation pressure and enthalpy of benzene

    International Nuclear Information System (INIS)

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

  6. Multiphoton ionization of benzene in solution

    International Nuclear Information System (INIS)

    The multiphoton ionization spectrum of benzene in a dilute solution in n-pentane has been measured for laser excitation wavelengths from 360-560 nm. The observed spectrum, from 460-560 nm, has been measured using linearly and circularly polarized light and has been ascribed to multiphoton ionization via the two-photon resonant 1B2/sub u/-1A1/sub q/ transitions of benzene. The order of the multiphoton ionization process has been determined, and the observed resonances in the spectral region from 360-445 nm are discussed. Power measurements at 337.1 nm indicate that two photons can ionize benzene in this energy region, giving an upper limit to the ionization threshold of benzene in n-pentane of approx.7.36 eV

  7. Effective ligand functionalization of zirconium-based metal-organic frameworks for the adsorption and separation of benzene and toluene: a multiscale computational study.

    Science.gov (United States)

    Wu, Ying; Chen, Huiyong; Liu, Defei; Xiao, Jing; Qian, Yu; Xi, Hongxia

    2015-03-18

    The adsorption and separation properties of benzene and toluene on the zirconium-based frameworks UiO-66, -67, -68, and their functional analogues UiO-Phe and UiO-Me2 were studied using grand canonical Monte Carlo simulations, density functional theory, and ideal adsorbed solution theory. Remarkable higher adsorption uptakes of benzene and toluene at low pressures on UiO-Phe and -Me2 were found compared to their parent framework UiO-67. It can be ascribed to the presence of functional groups (aromatic rings and methyl groups) that significantly intensified the adsorption, majorly by reducing the effective pore size and increasing the interaction strength with the adsorbates. At high pressures, the pore volumes and accessible surfaces of the frameworks turned out to be the dominant factors governing the adsorption. In the case of toluene/benzene separation, toluene selectivities of UiOs showed a two-stage separation behavior at the measured pressure range, resulting from the greater interaction affinities of toluene at low pressures and steric hindrance effects at high pressures. Additionally, the counterbalancing factors of enhanced ? delocalization and suitable pore size of UiO-Phe gave rise to the highest toluene selectivity, suggesting the ligand functionalization strategy could reach both high adsorption capacity and separation selectivity from aromatic mixtures at low concentrations. PMID:25700143

  8. Slow strain rate testing of carbon steel in solutions with high nitrate concentrations

    International Nuclear Information System (INIS)

    Processing of high-level nuclear waste for permanent disposal will cause changes to the present inhibited compositions at the Savannah River Site. Temperature and nitrate concentration may reach new high levels during salt dissolution in the carbon steel waste tanks with certain removal methods. Proper inhibitor concentrations are necessary to minimize the potential for nitrate-induced stress corrosion cracking to maintain the integrity of the waste tanks. Slow strain rate testing and potentiodynamic polarization were used to investigate whether stress corrosion cracking would initiate under bounding removal conditions. Test conditions for two carbon steels included nitrate concentrations of 5.5 and 9.7 M at a maximum temperature of 95 degrees C. The steels were found to be resistant to SCC in the more aggressive waste compositions at the present inhibitor concentrations of 0.6 M sodium hydroxide and 0.5 M sodium nitrite

  9. Pure and aligned carbon nanotubes produced by the pyrolysis of benzene-based aerosols

    International Nuclear Information System (INIS)

    The present work reports a method for preparing nanotubes involving pyrolysis of aerosols generated from benzene solutions of metallocenes. Different concentrations of ferrocene or ferrocene/nickelocene mixtures (65:35 and 25:75 Fe:Ni atomic ratios) were atomised with a compressed gas (Ar) driven sprayer, and pyrolysed at 800 or 950 deg. C. The black products, analyzed by SEM, (HR)TEM, and XRD, consisted of carpet-like aligned multi-walled nanotubes which are partly filled. The purity of the samples is generally high, but is drastically improved by using a ferrocene/nickelocene mixture 65:35 Fe:Ni. The changes in the nanotube size, and in the degree/size of filling, are reported as a function of synthesis parameters such as the nature and content of the metallocene, and the pyrolysis temperature

  10. Studies on the mechanism of benzene toxicity.

    OpenAIRE

    Snyder, R.; Dimitriadis, E.; Guy, R.; Hu, P.; Cooper, K.; Bauer, H.; Witz, G.; Goldstein, B. D.

    1989-01-01

    Using the 59Fe uptake method of Lee et al. it was shown that erythropoiesis in female mice was inhibited following IP administration of benzene, hydroquinone, p-benzoquinone, and muconaldehyde. Toluene protected against the effects of benzene. Coadministration of phenol plus either hydroquinone or catechol resulted in greatly increased toxicity. The combination of metabolites most effective in reducing iron uptake was hydroquinone plus muconaldehyde. We have also shown that treating animals w...

  11. Positron and positronium annihilation in benzene solutions

    International Nuclear Information System (INIS)

    Positron annihilation in nitrobenzene and manganese oleate solutions in benzene was studied in the liquid and solid states using both lifetime and angular correlation methods. It was found that a long lifetime component (tau2 approximately 1.3 ns) appeared in the lifetime spectrum for the solid state of a nitrobenzene solution in benzene but not in the liquid state. The results are briefly discussed. (orig.)

  12. Benzene, cytochrome, carcinogenesis: A topic in preventive toxicology

    OpenAIRE

    Wiwanitkit, Viroj

    2014-01-01

    Benzene is a common chemical substance with confirmed toxicity to human beings. The benzene toxicity can be in either acute or chronic. Also, the carcinogenicity of benzene is confirmed. Hence, the control of benzene usage is a topic in preventive toxicology; however, this substance is still problematic in many industrialized settings. In this article, the author discusses benzene and cytochrome focusing on the carcinogenesis process. A further extrapolation on the aspects on preventive toxic...

  13. Highly concentrated monoclonal antibody solutions: direct analysis of physical structure and thermal stability.

    Science.gov (United States)

    Harn, N; Allan, C; Oliver, C; Middaugh, C R

    2007-03-01

    Virtually all current analytical methods employed in the development of highly concentrated monoclonal antibody (MAb) formulations require dilution of the sample before acquiring data. Thus, there is an unmet need for methods to study proteins directly at high concentration, since extrapolation of stability indicating parameters obtained from dilute studies may not be representative of the high concentration solution. Only slight or no modifications of biophysical methods including fluorescence, UV absorbance, circular dichroism, and FTIR (ATR and transmittance) spectroscopies as well as differential scanning calorimetry (DSC) are described here that permit the direct study of immunoglobulins (and other proteins) at high concentrations. Although FTIR spectra show differences that are dependent upon sampling geometry, other spectroscopic data from two different recombinant MAbs suggests that structure of each antibody exists in a physically similar state in the concentration range of 0.1-190 mg/mL in 40 mM pH 6 citrate-phosphate buffer. Upon thermally stressing these proteins, spectroscopic techniques that probe tertiary structure demonstrate a decrease in the apparent thermal melting temperature of approximately 5-20 degrees C of both proteins with increasing concentration. In contrast, DSC thermograms and CD thermal experiments suggest a minor degree of stabilization (approximately 2 degrees C) for both antibodies although protein association could be responsible for these observations. Empirical phase diagrams produced from spectroscopic data also suggest (1) the existence of similar structural states at low temperatures independent of concentration and (2) a decrease in the temperature at which phase changes are observed with increasing concentration. The decrease in structural stability observed in these studies is probably the result of aggregation or self-association of the recombinant MAbs upon heating in crowded solutions and not due to a decrease in the intrinsic structural stability of the MAbs. PMID:17083094

  14. Effects of high dietary sulphur on enzyme activities, selenium concentrations and body weights of cattle.

    OpenAIRE

    Khan, A. A.; Lovejoy, D.; Sharma, A. K.; Sharma, R. M.; Prior, M. G.; Lillie, L. E.

    1987-01-01

    This study was designed to assess the effects of a moderate increase in dietary sulphur (S) in cattle. Twelve animals were initially fed a basal concentrate (S = 0.2%) and then divided into two groups; one fed basal and the other high S (S = 0.75%) concentrates. Health, body weight gains, and activities of erythrocyte enzymes-glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), glucose-6-phosphate dehydrogenase (G6PD), acetylcholinesterase (AChE), plasma- asparate aminotransferase (AS...

  15. Carbon dioxide as working fluid for medium and high-temperature concentrated solar thermal systems

    OpenAIRE

    Van Duong; Gerardo Diaz

    2014-01-01

    This paper explores the benefits and drawbacks of using carbon dioxide in solar thermal systems at medium and high operating temperatures. For medium temperatures, application of CO2 in non-imaging-optics based compound parabolic concentrators (CPC) combined with evacuated-tube collectors is studied. These collectors have been shown to obtain efficiencies higher than 40% operating at around 200°C without the need of tracking. Validated numerical models of external compound parabolic concentr...

  16. High frequency measurement of nitrate concentration in the Lower Mississippi River, USA

    Science.gov (United States)

    Duan, Shuiwang; Powell, Rodney T.; Bianchi, Thomas S.

    2014-11-01

    Nutrient concentrations in the Mississippi River have increased dramatically since the 1950s, and high frequency measurements on nitrate concentration are required for accurate load estimations and examinations on nitrate transport and transformation processes. This three year record of high temporal resolution (every 2-3 h) data clearly illustrates the importance of high frequency sampling in improving load estimates and resolving variations in nitrate concentration with river flow and tributary inputs. Our results showed large short-term (days to weeks) variations in nitrate concentration but with no diurnal patterns. A repeatable and pronounced seasonal pattern of nitrate concentration was observed, and showed gradual increases from the lowest values in September (during base-flow), to the highest in June - which was followed by a rapid decrease. This seasonal pattern was only moderately linked with water discharge, and more controlled by nitrogen transformation/export from watershed as well as mixing patterns of the two primary tributaries (the upper Mississippi and the Ohio Rivers), which have distinctly different nitrate concentrations and flow patterns. Based on continuous in situ flow measurements, we estimated 554-886 × 106 kg of nitrate-N was exported from the Mississippi River system during years 2004-2006, which was loads during rising stages and underestimated the loads during falling stages. While changes in nitrate concentrations in large rivers are generally not as responsive to alterations in diurnal inputs and/or watershed hydrology as small rivers, high-frequency water quality sampling would help in monitoring short-term (days to weeks) variations in nutrient concentration patterns and thus improve the accuracy of nutrient flux estimates.

  17. Influence of the non-polar diluent (benzene) on the recoil collection of 128I charged species under (n,?) process in methyl iodide target

    International Nuclear Information System (INIS)

    The collection of charged 128I recoil species produced in thermal neutron irradiated methyl iodide/benzene target on AgI/Ag electrodes showed low concentration on both the electrodes in presence of benzene than pure compound. Results are discussed on the basis of re-entry of recoil species as iodobenzene formation. (author)

  18. High Concentrating GaAs Cell Operation Using Optical Waveguide Solar Energy System

    Science.gov (United States)

    Nakamura, T.; Case, J. A.; Timmons, M. L.

    2004-01-01

    This paper discusses the result of the concentrating photovoltaic (CPV) cell experiments conducted with the Optical Waveguide (OW) Solar Energy System. The high concentration GaAs cells developed by Research Triangle Institute (RTI) were combined with the OW system in a "fiber-on-cell" configuration. The sell performance was tested up to the solar concentration of 327. Detailed V-I characteristics, power density and efficiency data were collected. It was shown that the CPV cells combined with the OW solar energy system will be an effective electric power generation device.

  19. Emergency response monitoring of a benzene release using the Ministry's mobile TAGA unit in southwestern Ontario

    International Nuclear Information System (INIS)

    This paper discussed the response tactics used by the Ontario Ministry of the Environment (MOE) Environmental Monitoring and Reporting Branch (EMRB) after an accidental chemical release at a petroleum refinery's distribution centre in Ontario. The release was caused by the floating roof failure of a feed tank. The EMRB was requested to measure airborne pollutant concentrations as the benzene mixture was transferred to another tank. The EMRB modelled the relative impact from the benzene release, acquired real time airborne pollutant concentration data, and determined benzene levels downwind of the feed tank. A mobile trace atmospheric gas analyzer (TAGA) unit was used to perform chemical fingerprints at 21 different locations. The TAGA unit remained in the area for a period of 17 days. Data collected from the unit was conveyed to the Ministry's Spill Action Centre as well as to several other federal agencies and First Nations groups in order to support further decision-making processes. 4 refs., 1 tab., 9 figs

  20. Ignition delay times of benzene and toluene with oxygen in argon mixtures

    Science.gov (United States)

    Burcat, A.; Snyder, C.; Brabbs, T.

    1985-01-01

    The ignition delay times of benzene and toluene with oxygen diluted in argon were investigated over a wide range of conditions. For benzene the concentration ranges were 0.42 to 1.69 percent fuel and 3.78 to 20.3 percent oxygen. The temperature range was 1212 to 1748 K and the reflected shock pressures were 1.7 to 7.89 atm. Statistical evaluation of the benzene experiments provided an overall equation which is given. For toluene the concentration ranges were 0.5 to 1.5 percent fuel and 4.48 to 13.45 percent oxygen. The temperature range was 1339 to 1797 K and the reflected shock pressures were 1.95 to 8.85 atm. The overall ignition delay equation for toluene after a statistical evaluation is also given. Detailed experimental information is provided.

  1. Solar surgery: remote fiber optic irradiation with highly concentrated sunlight in lieu of lasers

    Science.gov (United States)

    Feuermann, Daniel; Gordon, Jeffrey M.

    1998-10-01

    Highly concentrated sunlight has the power density required by many laser fiber optic surgical procedures. Thanks to recent progress in optical design, the means now exist to concentrate solar radiation in dielectrics to levels that exceed those at the surface of the sun, and to efficiently deliver it remotely. Since surgical power requirements are typically only several watts, the solar collection unit can be miniaturized. Although generating uncollimated radiation, solar surgery can serve as a low-cost alternative to laser fiber optic systems in treatments where wide-angle emissions are preferable. Even nominally monochromatic treatments such as photodynamic therapy can use highly concentrated sunlight because the power density within a typical wavelength window for these treatments (around 0.004 micrometer) is adequate to the task. Scheduling of solar surgery should not pose difficulties in clear climates. Solar concentration is performed in two stages: a paraboloidal reflector dish and a second-stage nonimaging concentrator. Concentrated irradiation would be transported via low-attenuation silica optical fibers to the operating room. With power delivery typically emanating from a disk of diameter 0.6 mm, the dish diameter would be in the vicinity of 200 mm with an even smaller system depth. The system could deliver a flux density as high as 70 W mm-2 for contact surgery and 30 W mm-2 for noncontact surgery. Aside from lasers, sunlight is uniquely suited to the task, in contrast to today's available light sources.

  2. High concentrations of myeloperoxidase in the equine uterus as an indicator of endometritis.

    Science.gov (United States)

    Parrilla-Hernandez, Sonia; Ponthier, Jérôme; Franck, Thierry Y; Serteyn, Didier D; Deleuze, Stéfan C

    2014-04-15

    Intraluminal fluid and excessive abnormal hyperedema are regularly used for the diagnosis of endometritis in the mare, which is routinely confirmed by the presence of neutrophils on endometrial smears. Studies show a relation between neutrophils and myeloperoxidase (MPO), an enzyme contained in and released by neutrophils during degranulation or after cell lysis. This enzyme has been found in many fluids and tissues, and associated with different inflammatory pathologies in the horse. The aims of this study were to assess the presence and concentration of MPO in the equine uterus, and to investigate its relation with neutrophils, and other clinical signs of endometritis. Mares (n = 51) were evaluated for the presence of intraluminal fluid and excessive endometrial edema before breeding, and a small volume lavage and cytology samples were obtained. From 69 cycles, supernatant of the uterine flushes was analyzed with a specific equine MPO ELISA assay to measure MPO concentration. Cytology samples were used for the diagnosis of endometritis. Myeloperoxidase was present in the uterus of all estrus mares in highly variable concentrations. Myeloperoxidase concentrations were significantly (P < 0.05) higher in samples with positive cytologies and in the presence of intraluminal fluid. Occasionally, some samples with negative cytologies showed high MPO concentration, but the opposite was never observed. Cycles presenting hyperedema weren't associated with high concentration of MPO, intraluminal fluid, or positive cytology, making it a poor diagnostic tool of endometritis. PMID:24565475

  3. Lower Salinomycin Concentration Increases Apoptotic Detachment in High-Density Cancer Cells

    OpenAIRE

    Sungpil Yoon; Hyung Sik Kim; Ju-Hwa Kim; Tae Young Kim; Suntaek Hong

    2012-01-01

    The present study identified a novel salinomycin (Sal) sensitization mechanism in cancer. We tested whether Sal reduced proliferation in a high-density population by counting attached cell numbers after Sal treatment. Sal reduced proliferation in high-density cell populations. Longer exposure to Sal further reduced proliferation. Sal concentrations of 0.1 and 5 ?M had similar sensitization effects, suggesting that Sal toxicity was minimal with longer exposure to a high-density cell pop...

  4. High efficiency solar cells for concentrator systems: silicon or multi-junction?

    Science.gov (United States)

    Slade, Alexander; Stone, Kenneth W.; Gordon, Robert; Garboushian, Vahan

    2005-08-01

    Amonix has become the first company to begin production of high concentration silicon solar cells where volumes are over 10 MW/year. Higher volumes are available due to the method of manufacture; Amonix solely uses semiconductor foundries for solar cell production. In the previous years of system and cell field testing, this method of manufacturing enabled Amonix to maintain a very low overhead while incurring a high cost for the solar cell. However, recent simplifications to the solar cell processing sequence resulted in cost reduction and increased yield. This new process has been tested by producing small qualities in very short time periods, enabling a simulation of high volume production. Results have included over 90% wafer yield, up to 100% die yield and world record performance (? =27.3%). This reduction in silicon solar cell cost has increased the required efficiency for multi-junction concentrator solar cells to be competitive / advantageous. Concentrator systems are emerging as a low-cost, high volume option for solar-generated electricity due to the very high utilization of the solar cell, leading to a much lower $/Watt cost of a photovoltaic system. Parallel to this is the onset of alternative solar cell technologies, such as the very high efficiency multi-junction solar cells developed at NREL over the last two decades. The relatively high cost of these type of solar cells has relegated their use to non-terrestrial applications. However, recent advancements in both multi-junction concentrator cell efficiency and their stability under high flux densities has made their large-scale terrestrial deployment significantly more viable. This paper presents Amonix's experience and testing results of both high-efficiency silicon rear-junction solar cells and multi-junction solar cells made for concentrated light operation.

  5. Electron beam purification of flue gas with high concentration of sulfur dioxide

    International Nuclear Information System (INIS)

    In order to apply the electron beam purification method to the flue gas containing high concentrations of SO2, a basic study was done with a simulated flue gas containing 4800 ppm of SO2. Removal efficiencies of SO2 and NOx were satisfactorily achieved to reach 97 and 88%, respectively, at 70 deg C with the dose of 10.3 kGy without any NH3 leakage. The higher concentrations of SO2, H2O, and added NH3 were found to be effective to oxidize NO to form NO2 and to oxidize SO2 to form SO3 in the process. The results obtained by the study clearly show that the electron beam processing will have high potential for the treatment of the flue gas containing a high concentration of SO2 such as that of the Bulgarian plant being constructed now. (author)

  6. High-dimensional orbital angular momentum entanglement concentration based on Laguerre–Gaussian mode selection

    International Nuclear Information System (INIS)

    Twisted photons enable the definition of a Hilbert space beyond two dimensions by orbital angular momentum (OAM) eigenstates. Here we propose a feasible entanglement concentration experiment, to enhance the quality of high-dimensional entanglement shared by twisted photon pairs. Our approach is started from the full characterization of entangled spiral bandwidth, and is then based on the careful selection of the Laguerre–Gaussian (LG) modes with specific radial and azimuthal indices p and ?. In particular, we demonstrate the possibility of high-dimensional entanglement concentration residing in the OAM subspace of up to 21 dimensions. By means of LabVIEW simulations with spatial light modulators, we show that the Shannon dimensionality could be employed to quantify the quality of the present concentration. Our scheme holds promise in quantum information applications defined in high-dimensional Hilbert space. (letter)

  7. Experimental Study of Sorbitol Production by Zymomonas mobilis in High Sucrose Concentration

    Directory of Open Access Journals (Sweden)

    Rui Sérgio dos Santos Ferreira da Silva

    2004-01-01

    Full Text Available The sorbitol presents several industrial applications and its conventional production is of high cost and low yield. Sorbitol production by Zymomonas mobilis production has attracted attention as both production cost and environmental impact are low. The sorbitol plays an osmo-protective rule so that its production is promoted by high sugar concentrations. This work has evaluated the effect of high sucrose concentration in the sorbitol production. The raise of sucrose concentration from 100 to 300g/ L caused an increase in the sorbitol production from 4,979 to 20,633g/l. Statistic analysis showed that 95,5% in the variation in sorbitol production can be explained.

  8. Intermolecular interactions in highly concentrated protein solutions upon compression and the role of the solvent

    Science.gov (United States)

    Grobelny, S.; Erlkamp, M.; Möller, J.; Tolan, M.; Winter, R.

    2014-12-01

    The influence of high hydrostatic pressure on the structure and protein-protein interaction potential of highly concentrated lysozyme solutions up to about 370 mg ml-1 was studied and analyzed using small-angle X-ray scattering in combination with a liquid-state theoretical approach. In the concentration region below 200 mg ml-1, the interaction parameters of lysozyme solutions are affected by pressure in a nonlinear way, which is probably due to significant changes in the structural properties of bulk water, i.e., due to a solvent-mediated effect. Conversely, for higher concentrated protein solutions, where hydration layers below ˜4 water molecules are reached, the interaction potential turns rather insensitive to compression. The onset of transient (dynamic) clustering is envisaged in this concentration range. Our results also show that pressure suppresses protein nucleation, aggregation and finally crystallization in supersaturated condensed protein solutions. These findings are of importance for controlling and fine-tuning protein crystallization. Moreover, these results are also important for understanding the high stability of highly concentrated protein solutions (as they occur intracellularly) in organisms thriving under hydrostatic pressure conditions such as in the deep sea, where pressures up to the kbar-level are reached.

  9. The ability of Typha domingensis to accumulate and tolerate high concentrations of Cr, Ni, and Zn.

    Science.gov (United States)

    Mufarrege, M M; Hadad, H R; Di Luca, G A; Maine, M A

    2015-01-01

    The tolerance and removal efficiency of Typha domingensis exposed to high concentrations of Cr, Ni, and Zn in single and combined treatments were studied. Sediment and two plants were disposed in each plastic reactor. The treatments were 100 and 500 mg L(-1) of Cr, Ni, and Zn (single solutions); 100 mg L(-1) Cr?+?Ni?+?Zn (multi-metal solutions) and 500 mg L(-1) Cr?+?Ni?+?Zn (multi-metal solutions); and a control. Even though the concentrations studied were extremely high, simulating an accidental metal dump, the three metals were efficiently removed from water. The highest removal was registered for Cr. The presence of other metals favored Cr and did not favor Ni and Zn removal from water. After 25 days, senescence and chlorosis of plants were observed in Ni and Comb500 treatments, while Cr and Zn only caused growth inhibition. T. domingensis accumulated high metal concentrations in tissues. The roots showed higher metal concentration than submerged parts of leaves. Cr translocation to aerial parts was enhanced by the presence of Ni and Zn. Our results demonstrate that in the case of an accidental dump of high Cr, Ni, and Zn concentrations, a wetland system dominated by T. domingensis is able to retain metals, and the macrophyte is able to tolerate them the time necessary to remove them from water. Thus, the environment will be preserved since the wetland would act as a cushion. PMID:25062549

  10. Inhibition of pure cultures of methanogens by benzene ring compounds.

    OpenAIRE

    Patel, G. B.; Agnew, B. J.; Dicaire, C. J.

    1991-01-01

    The inhibition of methane production by Methanosaeta concilii GP6, Methanospirillum hungatei GP1, Methanobacterium espanolae GP9, and Methanobacterium bryantii M.o.H. during short-term (6-h) exposure to eight benzene ring compounds was studied. The concentration that caused 50% inhibition of the methane production rate (IC50) was dependent on the species and the toxicant. Pentachlorophenol was the most toxic of the tested compounds, with an IC50 of less than 8 mg/liter for all species except ...

  11. Radiolysis of alkyl benzene sulfonate (ABS) in aqueous solution

    International Nuclear Information System (INIS)

    Degradation of alkyl benzene sulfonate (ABS) in aerated aqueous solution irradiated with gamma radiation with doses up to 1.8 kGy were studied. The degree of degradation, pH change, the effect of pH on the degradation, COD values and the degradation products were determined. The degradation of ABS increases with the increase of doses and decreases with the increase of ABS concentration. The degradation was somewhat more efficient in slightly acidic and neutral solutions than at basic pH oxalic acid was detected by HPLC as degradation product

  12. Evaluating the impact of high Pluronic(®) F68 concentrations on antibody producing CHO cell lines.

    Science.gov (United States)

    Tharmalingam, Tharmala; Goudar, Chetan T

    2015-04-01

    Pluronic(®) F68 (P-F68) is an important component of chemically-defined cell culture medium because it protects cells from hydrodynamic and bubble-induced shear in the bioreactor. While P-F68 is typically used in cell culture medium at a concentration of 1?g/L (0.1%), higher concentrations can offer additional shear protection and have also been shown to be beneficial during cryopreservation. Recent industry experience with variability in P-F68-associated shear-protection has opened up the possibility of elevated P-F68 concentrations in cell culture media, a topic that has not been previously explored in the context of industrial cell culture processes. Recognizing this gap, we first evaluated the effect of 1-5?g/L P-F68 concentrations in shake flask cultures over ten 3-day passages for cell lines A and B. Increase in terminal cell density and cell size was seen over time at higher P-F68 concentrations but protein productivity was not impacted. Results from this preliminary screening study suggested no adverse impact of high P-F68 concentrations. Subsequently fed-batch bioreactor experiments were conducted at 1 and 5?g/L P-F68 concentrations with both cell lines where cell growth, viability, metabolism, and product quality were examined under process conditions reflective of a commercial process. Results from these bioreactor experiments confirmed findings from the preliminary screen and also indicated no impact of elevated P-F68 concentration on product quality. If additional shear protection is desired, either due to raw material variability, cell line sensitivity, or a high-shear cell culture process, our results suggest this can be accomplished by elevating the P-F68 concentration in the cell culture medium without impacting cell culture performance and product quality. Biotechnol. Bioeng. 2015;112: 832-837. © 2014 Wiley Periodicals, Inc. PMID:25384465

  13. An assessment of a spiral duct centrifuge using standard and high concentration aerosols

    International Nuclear Information System (INIS)

    The Stoeber spiral duct centrifuge has been calibrated by means of polystyrene latex microspheres for the subsequent measurement of aerosol particle size distributions. Intermediate (1 g m-3) ad high (100 g m-3) sodium chloride aerosol concentrations have been sampled by the centrifuge to determine possible limitations in the equipment. Corrections have to be made for the effect of Coriolis forces, and aerosol concentrations above 1 g m-3 should be diluted before sampling. The spiral duct centrifuge is an extremely versatile instrument for aerosol analysis, and shows a high degree of reliability when operated under well-defined conditions. (author)

  14. High surface hole concentration p-type GaN using Mg implantation

    CERN Document Server

    Long Tao; Zhang Guo Yi

    2001-01-01

    Mg ions were implanted on Mg-doped GaN grown by metalorganic chemical vapor deposition (MOCVD). The p-type GaN was achieved with high hole concentration (8.28 x 10 sup 1 sup 7 cm sup - sup 3) conformed by Van derpauw Hall measurement after annealing at 800 degree C for 1 h. this is the first experimental report of Mg implantation on Mg-doped GaN and achieving p-type GaN with high surface hole concentration

  15. Installation of a bitumen coating plant for high-activity concentrates

    International Nuclear Information System (INIS)

    Following the excellent results obtained on the industrial coating of radioactive sludges, the possibility of solidifying also the evaporation concentrates with bitumen has been considered. For high activity concentrates, the use of bitumen is however limited by two main parameters: temperature resistance, irradiation resistance. By making use of the characteristics of a blown bitumen, it has been possible to design a high activity coating pilot plant treating concentrations of several tens of curies per litre. This plant will make use of a screw-type extrusion machine capable of coating treated concentrates at a rate of 20 l/hr. Before being coated, the concentrates will be subjected to a coprecipitation treatment designed to make the radioelements insoluble. This installation will make possible, apart from technological studies, laboratory experiments on the coated material (measurements on self-heating, on electrical charges, on radiolytic gases, and also lixiviation tests. It is at present believed, on the basis of available data, that it is possible to coat concentrates having an activity of 20 Ci/l at a price of 1840 F per cubic metre. (authors)

  16. Treatment of radioactive liquid waste in high salt concentration by chemical precipitation, (1)

    International Nuclear Information System (INIS)

    The principal co-precipitation mechanism of radioactive strontium with barium sulfate is the isomorphous replacement between Ba2+ and Sr2+ in the crystal. Thus, the removal ratio of radioactive strontium from an aqueous solution depends on the equilibrium constant, solubility product and quantities of barium sulfate, and SO42- concentration. In low salt concentration, the equilibrium constant K, for barium sulfate which was prepared with the reaction of Ba2+ and SO42- in the test solution was 1.9 x 10-4. On the other hand, the equilibrium constant for powdered barium sulfate added was K sub(s) = 9.1 x 10-6. In a high salt concentration less than about 3 x 10-1 mol/l NaCl and NaNO3, and less than about 1.0 mol/l Na2SO4, the experimental removal ratio agrees with the calculated values. But in high salt concentrations ranging from 3 x 10-3 mol/l to the saturated concentration of NaCl and NaNO3, ranging from 1.0 mol/l to the saturated concentration of Na2SO4, the experimental removal ratio decreases. (author)

  17. Rheological and syringeability properties of highly concentrated human polyclonal immunoglobulin solutions.

    Science.gov (United States)

    Burckbuchler, V; Mekhloufi, G; Giteau, A Paillard; Grossiord, J L; Huille, S; Agnely, F

    2010-11-01

    This study of highly concentrated polyvalent immunoglobulin solutions, IgG, aimed at analyzing the relationships between protein concentration and aggregation on the one hand and viscosity on the other hand. Viscosity variations as a function of IgG concentration showed two well-defined behaviours: a Newtonian behaviour for low-concentrated solutions and a shear-thinning behaviour for highly concentrated ones. The viscosity data fitted very well with the Mooney model, suggesting the absence of intermolecular interactions in the IgG solutions that behaved like a non-interacting suspension of hard particles. The polyclonal nature of IgG seems to prevent intermolecular interaction. The shape factor, determined from Mooney fitting, revealed a non-spherical shape of the polyclonal IgG molecules. The rheological properties were also correlated with the injection force (F) through hypodermic needles by syringeability tests. Here, F was mainly affected by three parameters: the solution viscosity, the injection flow rate, and the needle characteristics. In fact, syringeability tests showed that F increased with IgG concentration and flow rate and decreased with the internal diameter of the needle. A zone for optimal injection conditions was then identified taking into account the different affecting parameters and mainly a maximum force for manual injection, which was fixed at 30N. PMID:20719247

  18. Simplified yet highly accurate enzyme kinetics for cases of low substrate concentrations.

    Science.gov (United States)

    Härdin, Hanna M; Zagaris, Antonios; Krab, Klaas; Westerhoff, Hans V

    2009-10-01

    Much of enzyme kinetics builds on simplifications enabled by the quasi-steady-state approximation and is highly useful when the concentration of the enzyme is much lower than that of its substrate. However, in vivo, this condition is often violated. In the present study, we show that, under conditions of realistic yet high enzyme concentrations, the quasi-steady-state approximation may readily be off by more than a factor of four when predicting concentrations. We then present a novel extension of the quasi-steady-state approximation based on the zero-derivative principle, which requires considerably less theoretical work than did previous such extensions. We show that the first-order zero-derivative principle, already describes much more accurately the true enzyme dynamics at enzyme concentrations close to the concentration of their substrates. This should be particularly relevant for enzyme kinetics where the substrate is an enzyme, such as in phosphorelay and mitogen-activated protein kinase pathways. We illustrate this for the important example of the phosphotransferase system involved in glucose uptake, metabolism and signaling. We find that this system, with a potential complexity of nine dimensions, can be understood accurately using the first-order zero-derivative principle in terms of the behavior of a single variable with all other concentrations constrained to follow that behavior. PMID:19725885

  19. Methods to assess high-resolution subsurface gas concentrations and gas fluxes in wetland ecosystems

    DEFF Research Database (Denmark)

    Elberling, Bo; Kühl, Michael

    2013-01-01

    The need for measurements of soil gas concentrations and surface fluxes of greenhouse gases at high temporal and spatial resolution in wetland ecosystem has lead to the introduction of several new analytical techniques and methods. In addition to the automated flux chamber methodology for high-resolution estimates of greenhouse gas fluxes across the soil-atmosphere interface, these high-resolution methods include microsensors for quantification of spatiotemporal concentration dynamics in O2 and N2O at micrometer scales, fiber-optic optodes for long-term continuous point measurements of O2 concentrations, and planar optodes for high-resolution two-dimensional measurements of O2 and pH. This chapter summarizes the principles behind the methods and shows examples of new insights obtained using combinations of these different methods in a Danish fresh-water wetland system. The results highlight that wetland and peat soils are highly heterogeneous, containing a mosaic of dynamic macropore systems created by both macrofauna and flora leading to distinct spatial and temporal variations in gas concentration on a scale of millimeters and minutes. Applications of these new methodologies allow measurements of greenhouse gas dynamics in wetlands on a scale at which the underlying processes are regulated by microenvironmental controls.

  20. Optical performance evaluation of a solar furnace by measuring the highly concentrated solar flux

    International Nuclear Information System (INIS)

    We evaluated optical performance of a solar furnace in the KIER (Korea Institute of Energy Research) by measuring the highly concentrated solar flux with the flux mapping method. We presented and analyzed optical performance in terms of concentrated solar flux distribution and power distribution. We investigated concentration ratio, stagnation temperature, total power, and concentration accuracy with help of a modeling code based on the ray tracing method and thereby compared with other solar furnaces. We also discussed flux changes by shutter opening angles and by position adjustment of reflector facets. In the course of flux analysis, we provided a better understanding of reference flux measurement for calibration, reflectivity measurement with a portable reflectometer, shadowing area consideration for effective irradiation, as well as accuracy and repeatability of flux measurements. The results in the present study will help proper utilization of a solar furnace by facilitating comparison between flux measurements at different conditions and flux estimation during operation

  1. An analysis of workplace exposures to benzene over four decades at a petrochemical processing and manufacturing facility (1962-1999).

    Science.gov (United States)

    Sahmel, J; Devlin, K; Burns, A; Ferracini, T; Ground, M; Paustenbach, D

    2013-01-01

    Benzene, a known carcinogen, can be generated as a by-product during the use of petroleum-based raw materials in chemical manufacturing. The aim of this study was to analyze a large data set of benzene air concentration measurements collected over nearly 40 years during routine employee exposure monitoring at a petrochemical manufacturing facility. The facility used ethane, propane, and natural gas as raw materials in the production of common commercial materials such as polyethylene, polypropylene, waxes, adhesives, alcohols, and aldehydes. In total, 3607 benzene air samples were collected at the facility from 1962 to 1999. Of these, in total 2359 long-term (>1 h) personal exposure samples for benzene were collected during routine operations at the facility between 1974 and 1999. These samples were analyzed by division, department, and job title to establish employee benzene exposures in different areas of the facility over time. Sampling data were also analyzed by key events over time, including changes in the occupational exposure limits (OELs) for benzene and key equipment process changes at the facility. Although mean benzene concentrations varied according to operation, in nearly all cases measured benzene quantities were below the OEL in place at the time for benzene (10 ppm for 1974-1986 and 1 ppm for 1987-1999). Decreases in mean benzene air concentrations were also found when data were evaluated according to 7- to 10-yr periods following key equipment process changes. Further, an evaluation of mortality rates for a retrospective employee cohort (n = 3938) demonstrated that the average personal benzene exposures at this facility (0.89 ppm for the period 1974-1986 and 0.125 ppm for the period 1987-1999) did not result in increased standardized mortality ratio (SMRs) for diseases or malignancies of the lymphatic system. The robust nature of this data set provides comprehensive exposure information that may be useful for assessing human benzene exposures at similar facilities. The data also provide a basis for comparable measured exposure levels and the potential for adverse health effects. These data may also prove beneficial for comparing relative exposure potential for production versus nonproduction operations and the relationship between area and personal breathing zone samples. PMID:23980839

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

    International Nuclear Information System (INIS)

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

  3. Potential of membrane distillation for production of high quality fruit juice concentrate.

    Science.gov (United States)

    Onsekizoglu Bagci, Pelin

    2015-07-01

    Fruit juices are generally concentrated in order to improve the stability during storage and to reduce handling, packaging, and transportation costs. Thermal evaporation is the most widely used technique in industrial fruit juice concentrate production. In addition to high energy consumption, a large part of the characteristics determining the quality of the fresh juice including aroma, color, vitamins, and antioxidants undergoes remarkable alterations through the use of high operation temperatures. Increasing consumer demand for minimally or naturally processed stable products able to retain as much possible the uniqueness of the fresh fruit has engendered a growing interest for development of nonthermal approaches for fruit juice concentration. Among them, membrane distillation (MD) and its variants have attracted much attention for allowing very high concentrations to be reached under atmospheric pressure and temperatures near ambient temperature. This review will provide an overview of the current status and recent developments in the use of MD for concentration of fruit juices. In addition to the most basic concepts of MD variants, crucial suggestions for membrane selection and operating parameters will be presented. Challenges and future trends for industrial adaptation taking into account the possibility of integrating MD with other existing processes will be discussed. PMID:24915342

  4. Investigating DOC export dynamics using high-frequency instream concentration measurements

    Science.gov (United States)

    Oosterwoud, Marieke; Keller, Toralf; Musolff, Andreas; Frei, Sven; Park, Ji-Hyung; Fleckenstein, Jan H.

    2014-05-01

    Being able to monitor DOC concentrations using in-situ high frequency measurements makes it possible to better understand concentration-discharge behavior under different hydrological conditions. We developed a UV-Vis probe setup for modified/adapted use under field conditions. The quasi mobile probe setup allows a more flexible probe deployment. New or existing monitoring sites can easily be equipped for quasi-continuous monitoring or measurements can be performed at changing locations, without the need for additional infrastructure. We were able to gather high frequency data on DOC dynamics for one year in two streams in the Harz mountains in Germany. It proved that obtaining accurate DOC concentrations from the UV-Vis probes required frequent maintenance and probe calibration. The advantage of the setup over standard monitoring protocols becomes evident when comparing net exports over a year. In addition to mass improved balance calculations the high-frequency measurements can reveal intricate hysteretic relationships between discharge and concentrations that can provide valuable insights into the hydrologic dynamics and mechanisms that govern the delivery of DOC to the receiving waters. Measurements with similar probes from two additional catchments in Southern Germany and South Korea will be used to illustrate different discharge-concentration relationships and what can be learned from them about the hydrologic mechanisms that control the dynamics of DOC export.

  5. Influence of high electron concentration on band gap and effective electron mass of InN

    Energy Technology Data Exchange (ETDEWEB)

    Donmez, O.; Erol, A.; Arikan, M.C. [Science Faculty, Department of Physics, Istanbul University, Vezneciler, 34134 Istanbul (Turkey); Yilmaz, M.; Ulug, B.; Ulug, A. [Faculty of Arts and Science, Department of Physics, Akdeniz University, Dumlupinar Street, 07058 Antalya (Turkey); Ajagunna, A.O.; Iliopoulos, E.; Georgakilas, A. [IESL, FORTH and Physics Department, University of Crete, P.O. Box 1385, 71110 Heraklion-Crete (Greece)

    2011-05-15

    Effects of high electron concentration on the band gap energy of InN films having different layer thicknesses as 600 and 800 nm are investigated experimentally and theoretically. Electron concentrations of the samples are obtained through the Hall measurements accomplished between 77 K and room temperature. Optical characterization of the samples is carried out using the photoluminescence (PL) measurements and the observed PL spectra are explained considering the high electron concentration related effects, i.e. Burstein-Moss shift, band renormalization and band tailing in non-parabolic k . p model. Extracted PL results indicate that the samples have approximately 0.685 eV band gap energy at 77 K. Effective mass of the carriers, which is calculated as 0.097 m{sub 0} for electron concentration of {proportional_to}10{sup 19} cm{sup -3}, are also observed to be influenced by the high carrier concentration. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Performance of solmacs, a high PV solar concentrator with efficient optics

    Science.gov (United States)

    Thibert, T.; Hellin, M.-L.; Loicq, J.; Mazy, E.; Jacques, L.; Verstraeten, D.; Gillis, J.-M.; Languy, F.; Emmerechts, C.; Beeckman, E.; Habraken, S.; Lecat, J.-H.

    2012-10-01

    A new solar panel with high concentration photovoltaic technology (x700) has been designed, prototyped and tested in the SOLMACS project. The quality of concentrating optics is a key factor for high module efficiency. Therefore new dedicated PMMA Fresnel lenses were studied and produced by injection molding. Lens design, material and production process were optimized to achieve a high optical yield of 86%. Thorough lens performance assessment in optical laboratory was completed with lifetime UV aging tests. Another important aspect is the thermal control of the hot spot created under the solar cell that receives the concentrated flux of 700 Suns. A dedicated heat spreader was developed to achieve passive thermal control with minimum mass and cost. This was supported by thermal models and tests at both cell and module level. 35% triple junction cells were implemented in the module. Micro-assembly technologies were used for the cell packaging and electrical connections. In support to the research, a continuous solar simulator was designed and built to assess the system performance, both at component and module level. The concentrator developments were integrated in a prototype and tested both indoor with the simulator and outdoor on the CSL solar test platform. The overall efficiency of the PV concentrator module is 28.5%.

  7. The role of benzene photolysis in Titan haze formation

    Science.gov (United States)

    Yoon, Y. Heidi; Hörst, Sarah M.; Hicks, Raea K.; Li, Rui; de Gouw, Joost A.; Tolbert, Margaret A.

    2014-05-01

    During the Cassini mission to the saturnian system, benzene (C6H6) was observed throughout Titan’s atmosphere. Although present in trace amounts, benzene has been proposed to be an important precursor for polycyclic aromatic hydrocarbon formation, which could eventually lead to haze production. In this work, we simulate the effect of benzene in Titan’s atmosphere in the laboratory by using a deuterium lamp (115-400 nm) to irradiate CH4/N2 gas mixtures containing ppm-levels of C6H6. Proton-transfer ion-trap mass spectrometry is used to detect gas-phase products in situ. HCN and CH3CN are identified as two major gases formed from the photolysis of 2% CH4 in N2, both with and without 1 ppmv C6H6 added. Inclusion of benzene significantly increases the total amount of gas-phase products formed and the aromaticity of the resultant gases, as shown by delta analysis of the mass spectra. The condensed phase products (or tholins) are measured in situ using high-resolution time-of-flight aerosol mass spectrometry. As reported previously by Trainer et al. (Trainer, M.G., Sebree, J.A., Yoon, Y.H., Tolbert, M.A. [2013]. Astrophys. J. 766, L4), the addition of C6H6 is shown to increase aerosol mass, but decrease the nitrogen incorporation in the organic aerosol. The pressure dependence of aerosol formation for the C6H6/CH4/N2 gas mixture is also explored. As the pressure decreases, the %N by mass in the aerosol products decreases.

  8. Small-angle neutron scattering studies of sodium butyl benzene sulfonate aggregates in aqueous solution

    International Nuclear Information System (INIS)

    The aggregation behaviour of a hydrotrope, sodium n-butyl benzene sulfonate (Na-NBBS), in aqueous solutions is investigated by small-angle neutron scattering (SANS). Nearly ellipsoidal aggregates of Na-NBBS at concentrations well above its minimum hydrotrope concentration were detected by SANS. The hydrotrope seems to form self-assemblies with aggregation number of 36-40 with a substantial charge on the aggregate. This aggregation number is weakly affected by the hydrotrope concentration. (author)

  9. Pervaporation Characteristics in Removal of Benzene from Water through Polystyrene-Poly (Dimethylsiloxane IPN Membranes

    Directory of Open Access Journals (Sweden)

    Tatsuo Yajima

    2011-03-01

    Full Text Available This paper focuses on the effects of the PSt content of polystyrene (PSt-poly (dimethylsiloxane (PDMS interpenetrateing network (IPN polymer membranes, on the pervaporation (PV characteristics during the removal of benzene from an aqueous solution of dilute benzene. When an aqueous solution of 0.05wt% benzene was permeated through the PSt-PDMS IPN membranes, they showed high benzene/water selectivity. Both the permeability and the benzene/water selectivity of the membranes were enhanced with increasing PSt content in the PSt-PDMS IPN membrane. The physicochemical mechanism of permeation and separation through the PSt-PDMS IPN membranes during PV is also discussed. The best normalized permeation rate, separation factor for benzene selectivity, and PV separation index of the PSt-PDMS IPN membrane were 1.27 × 10-6 kgm (m2hr-1, 3293, and 41821, respectively. These PV characteristics are discussed from the viewpoint of the chemical and physical structure of the PSt-PDMS IPN membranes.

  10. Radiolysis of Aqueous Benzene Solutions

    International Nuclear Information System (INIS)

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

  11. Anaerobic benzene oxidation via phenol in Geobacter metallireducens.

    Science.gov (United States)

    Zhang, Tian; Tremblay, Pier-Luc; Chaurasia, Akhilesh Kumar; Smith, Jessica A; Bain, Timothy S; Lovley, Derek R

    2013-12-01

    Anaerobic activation of benzene is expected to represent a novel biochemistry of environmental significance. Therefore, benzene metabolism was investigated in Geobacter metallireducens, the only genetically tractable organism known to anaerobically degrade benzene. Trace amounts (Geobacter metallireducens anaerobically oxidizing benzene to carbon dioxide with the reduction of Fe(III). Phenol was not detected in cell-free controls or in Fe(II)- and benzene-containing cultures of Geobacter sulfurreducens, a Geobacter species that cannot metabolize benzene. The phenol produced in G. metallireducens cultures was labeled with (18)O during growth in H2(18)O, as expected for anaerobic conversion of benzene to phenol. Analysis of whole-genome gene expression patterns indicated that genes for phenol metabolism were upregulated during growth on benzene but that genes for benzoate or toluene metabolism were not, further suggesting that phenol was an intermediate in benzene metabolism. Deletion of the genes for PpsA or PpcB, subunits of two enzymes specifically required for the metabolism of phenol, removed the capacity for benzene metabolism. These results demonstrate that benzene hydroxylation to phenol is an alternative to carboxylation for anaerobic benzene activation and suggest that this may be an important metabolic route for benzene removal in petroleum-contaminated groundwaters, in which Geobacter species are considered to play an important role in anaerobic benzene degradation. PMID:24096430

  12. High energy shock waves induced increase in the local concentration of systemically given TNF-alpha.

    Science.gov (United States)

    Cornel, E B; Oosterwijk, E; van de Streek, J D; Grutters, G; Debruyne, F M; Schalken, J A; Oosterhof, G O

    1994-12-01

    The influence of high energy shock waves (HESW) on the local concentration of systemically given TNF-alpha was studied in a syngeneic rat bladder tumor model. 125I-TNF-alpha was injected intravenously and within 1 minute was followed by HESW tumor exposure. High energy shock waves were generated using an experimental shock wave emitter based on the Siemens Lithostar Plus. Administration of HESW to RBT323 tumors resulted in a 3-fold increase in uptake of 125I-TNF-alpha in the tumor compared with nontreated tumors, whereas the tissue distribution and pharmacokinetics of nontumor tissue were similar irrespective of HESW exposure. These results demonstrate that HESW administration leads to an increase in the local concentration of a systemically given drug. The capacity of HESW to increase local drug concentrations will be of importance in designing more effective combined treatment strategies. PMID:7966708

  13. Preparation of a high concentration of lithium-7 atoms in a magneto-optical trap

    Energy Technology Data Exchange (ETDEWEB)

    Zelener, B. B., E-mail: bobozel@mail.ru; Saakyan, S. A.; Sautenkov, V. A. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation); Manykin, E. A. [National Research Nuclear University “Moscow Engineering Physics Institute,” (Russian Federation); Zelener, B. V.; Fortov, V. E. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

    2014-11-15

    This study is aimed at obtaining high concentration of optically cooled lithium-7 atoms for preparing strongly interacting ultracold plasma and Rydberg matter. A special setup has been constructed, in which two high-power semiconductor lasers are used to cool lithium-7 atoms in a magneto-optical trap. At an optimum detuning of the cooling laser frequency and a magnetic field gradient of 35 G/cm, the concentration of ultracold lithium-7 atoms reaches about 10{sup 11} cm{sup ?3}. Additional independent information about the concentration and number of ultracold lithium-7 atoms on different sublevels of the ground state was obtained by using of an additional probing laser.

  14. Metal dynamics and tolerance of Typha domingensis exposed to high concentrations of Cr, Ni and Zn.

    Science.gov (United States)

    Mufarrege, M M; Hadad, H R; Di Luca, G A; Maine, M A

    2014-07-01

    Typha domingensis was exposed to a 100mgL(-1) Cr+100mgL(-1) Ni+100mgL(-1) Zn solution. Metal tolerance and metal accumulation in plant tissues and sediment were studied over time. Although removal rates were different, the three metals were efficiently removed from water. Leaf and root tissues showed high metal concentration. However, the sediment showed the highest accumulation. During the first hours of contact, metals were not only accumulated by sediment and roots but they were also taken up by the leaves in direct contact with the solution. Over time, metals were translocated from roots to leaves and vice versa. Metals caused growth inhibition and a decrease in chlorophyll concentration and affected anatomical parameters. Despite these sub-lethal effects, T. domingensis demonstrated that it could accumulate Cr, Ni and Zn efficiently and survive an accidental dump of high concentrations of contaminants in systems such as natural and constructed wetlands. PMID:24793518

  15. Modifications to the standard additions method for components at very high concentrations

    International Nuclear Information System (INIS)

    Limitations to the classical methods of standard additions (MSA) are discussed and overcome by the proposed modifications to the method. The modifications permit accurate linear regression determination of analytes at very high concentrations (>5%) in complex materials where matrix matching is difficult or where appropriate standard reference materials (SRM) are not available. The modifications are demonstrated with X-ray diffraction (XRD) determination of ? (56.5%) and amorphous (23.9%) phase concentrations in fumed alumina, which contains a variety of crystalline phases. The modified method may be especially suited to analysis of solids and powders with techniques such as XRD, X-ray fluorescence (XRF), and Raman spectroscopy where similar very high-analyte concentration and sample matrix complexity are commonly encountered, provided that the assumptions of the method can be met

  16. TREATMENT OF HIGH ETHANOL CONCENTRATION WASTEWATER BY CONSTRUCTED WETLANDS: ENHANCED COD REMOVAL AND BACTERIAL COMMUNITY DYNAMICS

    OpenAIRE

    Rodriguez Caballero, Adrian

    2011-01-01

    Winery wastewater is characterized by its high chemical oxygen demand (COD), seasonal occurrence and variable composition, including periodic high ethanol concentrations. In addition, winery wastewater may contain insufficient inorganic nutrients for optimal biodegradation of organic constituents. Two pilot-scale constructed wetlands (CWs) were used to treat artificial wastewater: the first was amended with ethanol and the second with ethanol, inorganic nitrogen (N) and phosphorus (P). A numb...

  17. High frequency ultrasound penetration through concentric tubes: illustrating cooling effects and cavitation intensity

    Science.gov (United States)

    Rahimi, Masoud; Abolhasani, Mahdieh; Azimi, Neda

    2015-04-01

    Effective cooling of water by using high frequency ultrasound waves in two concentric straight tubes was investigated. The outer tube was equipped with eight 1.7 MHz ultrasound transducers. The cavitation intensity in both tubes was examined by employing the Weissler reaction. The experimental results showed that employing the 1.7 MHz ultrasound waves caused high temperature drop in the internal tube while no significant thermal effects occurred in the outer tube.

  18. A SIMPLE WAY OF ACHIEVING A HIGH CELL CONCENTRATION IN RECOMBINANT Escherichia coli CULTIVATION

    OpenAIRE

    Gombert, A. K.; Kilikian, B. V.

    1997-01-01

    Abstract - A cultivation strategy based on some previous knowledge of the metabolism of Escherichia coli BL21 (DE3) pLysS containing the troponin C gene cloned into plasmid pET was developed and applied through the use of simple fermentation equipment and a feed-forward control strategy in order to achieve a high cell concentration ¾ 92 g l-1 dry cell weight ¾ and a high cell productivity ¾ 3.7 g l-1 h-1.

  19. A SIMPLE WAY OF ACHIEVING A HIGH CELL CONCENTRATION IN RECOMBINANT Escherichia coli CULTIVATION

    Directory of Open Access Journals (Sweden)

    Gombert A.K.

    1997-01-01

    Full Text Available Abstract - A cultivation strategy based on some previous knowledge of the metabolism of Escherichia coli BL21 (DE3 pLysS containing the troponin C gene cloned into plasmid pET was developed and applied through the use of simple fermentation equipment and a feed-forward control strategy in order to achieve a high cell concentration ¾ 92 g l-1 dry cell weight ¾ and a high cell productivity ¾ 3.7 g l-1 h-1.

  20. Analytical Study of High Concentration PCB Paint at the Heavy Water Components Test Reactor

    International Nuclear Information System (INIS)

    This report provides results of an analytical study of high concentration PCB paint in a shutdown nuclear test reactor located at the US Department of Energy's Savannah River Site (SRS). The study was designed to obtain data relevant for an evaluation of potential hazards associated with the use of and exposure to such paints

  1. Analytical Study of High Concentration PCB Paint at the Heavy Water Components Test Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Lowry, N.J.

    1998-10-21

    This report provides results of an analytical study of high concentration PCB paint in a shutdown nuclear test reactor located at the US Department of Energy's Savannah River Site (SRS). The study was designed to obtain data relevant for an evaluation of potential hazards associated with the use of and exposure to such paints.

  2. Synthesis of dodecyl lauroyl benzene sulfonate and its application in enhanced oil recovery

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Zhenggang; Wu, Le; Sun, Mingming; Jiang, Jian-zhong; Wang, Feng [Jiangnan Univ., Wuxi (China). School of Chemical and Material Engineering

    2011-09-15

    A new hydrophobic surfactant, dodecyl lauroyl benzene sulfonate (DLBS), was synthesized and its application in enhanced oil recovery by alkali-surfactant-polymer (ASP) flooding was studied. The results show that DLBS can be synthesized by reaction of industrial dodecyl benzene with lauroyl chloride in the presence of AlCl{sub 3}, followed by sulfonation with ClSO{sub 3}H and neutralization with NaOH. The lauroyl-group is confirmed to be connected to the para-position of the alkylbenzene by1HNMR spectrum. The synthesized DLBS is well soluble in pure water and reservoir (connate) water at 45 C. It is highly surface active which is indicated by its low CMC of 1.1 . 10{sup -5} mol/L, and its low surface tension, {gamma}{sub cmc} of 28.6 mN m{sup -1}. By mixing with heavy alkylbenzene sulfonates of relatively low average molar mass (387g mol{sup -1}) at a total surfactant concentration of 5 mM, DLBS can reduce the interfacial tension of Daqing crude oil/connate water to an order of 10{sup -3} mN/m at 45 C in the presence of 0.5-1.0 wt.% NaOH and 1000 mg L{sup -1} of polymer. If the NaOH was replaced by a gentle alkaline salt, Na{sub 2}CO{sub 3}, certain amounts of dodecyl dimethyl carboxy betaine were added and the concentration of Na{sub 2}CO{sub 3} was increased to 1.2-2.0 wt.%, the interfacial tension of Daqing crude oil/connate water can also be reduced to an ultralow value. Therefore DLBS is a good hydrophobic surfactant applicable in ASP flooding with either NaOH or Na{sub 2}CO{sub 3} as alkaline agents. (orig.)

  3. ACUTE AND CHRONIC TOXICITY OF SOME CHLORINATED BENZENES, CHLORINATED ETHANES, AND TETRACHLOROETHYLENE TO 'DAPHNIA MAGNA'

    Science.gov (United States)

    Chronic effect and no effect concentrations (28 day) and acute toxicity (48 hr, LC50 and EC50) values were determined for Daphnia magna with some chlorinated benzenes, chlorinated ethanes, and tetrachloroethylene. Acute and chronic toxicity generally increased with the degree of ...

  4. BENZENE METABOLISM IN RODENTS AT DOSES RELEVANT TO HUMAN EXPOSURE FROM URBAN AIR

    Science.gov (United States)

    Investigators, led by Dr. Kenneth Turteltaub, researched benzene metabolism in rodents over a hundred million–fold dose range. This range encompassed concentrations close to those of human ambient exposure, generally 1 to 10 parts per billion. Turteltaub and his ...

  5. Response of Salvinia cucullata to high NH4(+) concentrations at laboratory scales.

    Science.gov (United States)

    Jampeetong, Arunothai; Brix, Hans; Kantawanichkul, Suwasa

    2012-05-01

    Growth, morphology, NH(4)(+) uptake and mineral allocation in Salvinia cucullata Roxb. ex Bory grown with different amounts of NH(4)(+) were investigated. Plants of uniform size were grown on full strength Smart and Barko medium with different NH(4)(+) concentrations (0.5, 1, 5, 10 and 15 mM) and incubated in a greenhouse for four weeks. Salvinia cucullata grew well in the medium with 0.5-1 mM NH(4)(+) with a relative growth rate of 0.11-0.12 d(-1) without exhibiting NH(4)(+) toxicity symptoms. With an NH(4)(+) concentration above 5 mM, plant growth was suppressed and signs of NH(4)(+) toxicity were observed. NH(4)(+) toxicity symptoms were obvious in plants supplied with 10 mM and 15 mM NH(4)(+). These plants had low growth rates, short roots, low numbers of roots and showed chlorosis. Rotted roots and stems were also found in plants fed with 15 mM NH(4)(+). This species had a high uptake rate even though the NH(4)(+) concentrations increased, making it an ideal candidate for growth in eutrophic environments. The high NH(4)(+) concentration had a negative effect on K uptake resulting in low K concentration in the plant tissue, but the plants increased N content in plant tissue. Thus, harvested plants can be used as soil fertilizer or for animal feed. Furthermore, maintaining plant biomass can improve the efficiency of water treatment. PMID:22195762

  6. A design for automatic preparation of highly concentrated 188Re-perrhenate solutions

    International Nuclear Information System (INIS)

    Rhenium-188 is extremely suitable for the radiotherapy of balloon dilation for the coronary artery restenosis. To satisfy the need of highly concentrated 188Re-perrhenate for the clinical applications, we designed an apparatus to achieve the purpose of concentrating 188Re-perrhenate solution. This apparatus comprised of a concentrator, a control box and a computer with an automatic control program. A column of cation-exchange resin in Ag+ form and an anion-exchange column in series were used in the concentration procedure. More than 90% of 188Re isotope in the original solution could be collected with 1mL of 0.9% NaCl solution added to collect the 188Re adsorbed in the column in this final process (90.7+/-2.2%, n=15). We also found that the radiochemical purity in the final solution remained unchanged (100%). The designed process could automatically increase the quality and efficiency of the production of highly concentrated rhenium-188 solution, and could also reduce the radiation dose absorbed by the operator

  7. The molecular interaction of a protein in highly concentrated solution investigated by Raman spectroscopy.

    Science.gov (United States)

    Ota, Chikashi; Noguchi, Shintaro; Tsumoto, Kouhei

    2015-04-01

    We used Raman spectroscopy to investigate the structure and interactions of lysozyme molecules in solution over a wide range of concentrations (2.5-300 mg ml(-1) ). No changes in the amide-I band were observed as the concentration was increased, but the width of the Trp band at 1555 cm(-1) and the ratios of the intensities of the Tyr bands at 856 and 837 cm(-1) , the Trp bands at 870 and 877 cm(-1) , and the bands at 2940 (CH stretching) and 3420 cm(-1) (OH stretching) changed as the concentration was changed. These results reveal that although the distance between lysozyme molecules changed by more than an order of magnitude over the tested concentration range, the secondary structure of the protein did not change. The changes in the molecular interactions occurred in a stepwise process as the order of magnitude of the distance between molecules changed. These results suggest that Raman bands can be used as markers to investigate the behavior of high-concentration solutions of proteins and that the use of Raman spectroscopy will lead to progress in our understanding not only of the basic science of protein behavior under concentrated (i.e., crowded) conditions but also of practical processes involving proteins, such as in the field of biopharmaceuticals. © 2014 Wiley Periodicals, Inc. Biopolymers 103: 237-246, 2015. PMID:25418947

  8. Off-pathway aggregation can inhibit fibrillation at high protein concentrations

    DEFF Research Database (Denmark)

    Deva, Taru; Lorenzen, Nikolai

    2013-01-01

    Ribosomal protein S6 fibrillates readily at slightly elevated temperatures and acidic pH. We find that S6 fibrillation is retarded rather than favored when the protein concentration is increased above a threshold concentration of around 3.5mg/mL. We name this threshold concentration C(FR), the concentration at which fibrillation is retarded. Our data are consistent with a model in which this inhibition is due to the formation of an off-pathway oligomeric species with native-like secondary structure. The oligomeric species dominates at high protein concentrations but exists in dynamic equilibrium with the monomer so that seeding with fibrils can overrule oligomer formation and favors fibrillation under C(FR) conditions. Thus, fibrillation competes with formation of off-pathway oligomers, probably due to a monomeric conversion step that is required to commit the protein to the fibrillation pathway. The S6 oligomer is resistant to pepsin digestion. We also report that S6 forms different types of fibrils dependent on protein concentration. Our observations highlight the multitude of conformational states available to proteins under destabilizing conditions.

  9. Structural design for high-power parabolic trough concentrator arrays in space

    Science.gov (United States)

    Stern, T. G.; Hayes, E. W.

    The design of a support structure for a space-power photovoltaic concentrator is described. The baseline concentrator uses miniaturized parabolic-trough mirror-radiators to illuminate solar cells at concentration ratios in the range from 10-40 x geometrical. Such a concentrator has unique pointing requirements in that high accuracy (2 degrees) is required in the axis of concentration, while the perpendicular axis allows greater pointing errors (10 degrees or more) with minimal power loss. The array structure was designed with the goal of meeting these pointing requirements under the constraints of given mirror lengths, payload-bay packaging envelopes, and operating disturbances. Structural design parameters included structure weight, array aperture efficiency (packing factor), and packaged volumetric efficiency. The proposed structure uses a rectangular grid of graphite composite beams backed by a rigidized truss to form a triangular cross-section. This design has projected specific mass as low as 1 kg/sq m for the structural fraction of the array, and can result in concentrator specific powers exceeding 60 W/kg using current technology.

  10. Irradiation with benzene, toluene and phenol electron beams in aqueous solution

    International Nuclear Information System (INIS)

    It is described a methodology for waste water treatment which is simulated doing a benzene-toluene-phenol mixture in aqueous solution. Three different concentrations of them ones were used which were irradiated with electron beams coming from a Pelletron Accelerator carrying out the degradation effect of these compounds in CO2 and H2O. By mean of gas chromatography the analytical determinations were realized finding that in lower concentration of benzene and toluene performances of degradation higher than 95 % were obtained, but higher concentrations (100 ppm) the performance diminishes at 89 %, while for phenol in higher concentrations its degradation is over 60 % and in lower concentrations the degradation is under 80 %. The results are obtained with a constant irradiation time of 12 seconds and neutral pH. (Author

  11. A high plasma concentration of TNF-alpha is associated with dementia in centenarians

    DEFF Research Database (Denmark)

    Bruunsgaard, H.; Andersen-Ranberg, K.

    1999-01-01

    Background Inflammatory mechanisms and immune activation have been hypothesized to play a role in the pathogenesis of age-associated diseases such as dementia and atherosclerosis. The purpose of this study was to evaluate the plasma concentration of tumor necrosis factor (TNF)-alpha in a large cohort of centenarians and to look for its possible associations with cognitive function, atherosclerosis, and general health status. Furthermore, we investigated whether the concentration of TNF-alpha was correlated with the blood concentration of leucocyte subsets or the plasma concentrations of interleukin (IL)-6, soluble TNF receptor II (sTNFR-II) (75 kDa) and C-reactive protein (CRP). Methods. Plasma TNF-alpha was measured by ELISA in 126 centenarians, 45 subjects aged 81 years, 23 subjects aged 55-65 years, and 38 subjects aged 18-30 years. Atherosclerosis was evaluated by the ankle-brachial blood pressure index, and general health status was evaluated by the body mass index and the number of diagnoses present Results. The concentration of TNF-alpha was significantly increased in 126 centenarians compared to younger control groups, and a high concentration of TNF-alpha was associated with both Alzheimer's disease and generalized atherosclerosis in the centenarians. The concentration of TNF-alpha was positively correlated with the concentrations of plasma IL-6, sTNFR-II, and CRP. No associations were found with increased leucocyte subsets or the body mass index. Conclusion. This study demonstrates that, even in apparently healthy subjects, age-associated immune activation indicated by raised levels of pro-inflammatory cytokines may reflect age-associated pathological processes that develop over decades.

  12. Aggregation of Normal and Sickle Hemoglobin in High Concentration Phosphate Buffer

    Science.gov (United States)

    Chen, Kejing; Ballas, Samir K.; Hantgan, Roy R.; Kim-Shapiro, Daniel B.

    2004-01-01

    Sickle cell disease is caused by a mutant form of hemoglobin, hemoglobin S, that polymerizes under hypoxic conditions. The extent and mechanism of polymerization are thus the subject of many studies of the pathophysiology of the disease and potential treatment strategies. To facilitate such studies, a model system using high concentration phosphate buffer (1.5 M–1.8 M) has been developed. To properly interpret results from studies using this model it is important to understand the similarities and differences in hemoglobin S polymerization in the model compared to polymerization under physiological conditions. In this article, we show that hemoglobin S and normal adult hemoglobin, hemoglobin A, aggregate in high concentration phosphate buffer even when the concentration of hemoglobin is below the solubility defined for polymerization. This phenomenon was not observed using 0.05 M phosphate buffer or in another model system we studied that uses dextran to enhance polymerization. We have used static light scattering, dynamic light scattering, and differential interference contrast microscopy to confirm aggregation of deoxygenated and oxygenated hemoglobins below their solubility and have shown that this aggregation is not observable using turbidity measurements, a common technique for assessing polymerization. We have also shown that the aggregation increases with increasing temperature in the range of 15°–37°C and that it increases as the concentration of phosphate increases. These studies contribute to the working knowledge of how to properly apply studies of hemoglobin S polymerization that are conducted using the high phosphate model. PMID:15465861

  13. The potential of np GaAs solar cells for high efficiency concentrator applications

    Science.gov (United States)

    Flat, A.; Milnes, A. G.

    1979-01-01

    This communication considers the design of the front grid contact of np GaAs solar cells for high efficiency concentrator applications. This design involves shadowing, contact resistance, and active layer sheet resistance losses, and at high concentrations, the power loss due to voltage drop on the resistance of the grid fingers should be considered. Analysis of the performance can be calculated as a function of junction depth and surface recombination velocity. The junction depth can be optimized by considering its effect on the collection efficiency of the dark current-voltage characteristics or the open circuit voltage, and on the series resistance loss or the fill factor for material parameters. The choice of the material parameters, calculation of the short circuit current, the selection of the n layer thickness, and the cell maximum power and efficiency are discussed. It is concluded that optimized multi-grid structures should allow the use of 10 by 10 sq cm cells with good efficiencies at high concentration ratios, and efficiencies of 22 to 25% should be obtainable from large area cells at concentrations of 40 AM1.

  14. The osmotic pressure of highly concentrated monoclonal antibody solutions: effect of solution conditions.

    Science.gov (United States)

    Binabaji, Elaheh; Rao, Suma; Zydney, Andrew L

    2014-03-01

    The behavior of monoclonal antibodies at high concentrations is important in downstream processing, drug formulation, and drug delivery. The objective of this study was to evaluate the osmotic pressure of a highly purified monoclonal antibody at concentrations up to 250 g/L over a range of pH and ionic strength, and in the presence of specific excipients, using membrane osmometry. Independent measurements of the second virial coefficient were obtained using self-interaction chromatography, and the net protein charge was evaluated using electrophoretic light scattering. The osmotic pressure at pH 5 and low ionic strength was >50 kPa for antibody concentrations above 200 g/L. The second virial coefficients determined from the oncotic pressure (after subtracting the Donnan contribution) were in good qualitative agreement with those determined by self-interaction chromatography. The second virial coefficient decreased with increasing ionic strength and increasing pH due to the reduction in intermolecular electrostatic repulsion. The third virial coefficient was negative under all conditions, suggesting that multi-body interactions in this system are attractive. The virial coefficients were essentially unaffected by addition of sucrose or proline. These results have important implications for the analysis of protein-protein interactions in downstream processing at high protein concentrations. PMID:23996891

  15. Vasopressin activates Akt/mTOR pathway in smooth muscle cells cultured in high glucose concentration

    Energy Technology Data Exchange (ETDEWEB)

    Montes, Daniela K.; Brenet, Marianne; Muñoz, Vanessa C.; Burgos, Patricia V.; Villanueva, Carolina I. [Department of Physiology, Universidad Austral de Chile, Valdivia 509-9200 (Chile); Figueroa, Carlos D. [Department of Anatomy, Histology and Pathology, Universidad Austral de Chile, Valdivia 509-9200 (Chile); González, Carlos B., E-mail: cbgonzal@uach.cl [Department of Physiology, Universidad Austral de Chile, Valdivia 509-9200 (Chile); Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555 (United States)

    2013-11-29

    Highlights: •AVP induces mTOR phosphorylation in A-10 cells cultured in high glucose concentration. •The mTOR phosphorylation is mediated by the PI3K/Akt pathway activation. •The AVP-induced mTOR phosphorylation inhibited autophagy and stimulated cell proliferation. -- Abstract: Mammalian target of rapamycin (mTOR) complex is a key regulator of autophagy, cell growth and proliferation. Here, we studied the effects of arginine vasopressin (AVP) on mTOR activation in vascular smooth muscle cells cultured in high glucose concentration. AVP induced the mTOR phosphorylation in A-10 cells grown in high glucose, in contrast to cells cultured in normal glucose; wherein, only basal phosphorylation was observed. The AVP-induced mTOR phosphorylation was inhibited by a PI3K inhibitor. Moreover, the AVP-induced mTOR activation inhibited autophagy and increased thymidine incorporation in cells grown in high glucose. This increase was abolished by rapamycin which inhibits the mTORC1 complex formation. Our results suggest that AVP stimulates mTOR phosphorylation by activating the PI3K/Akt signaling pathway and, subsequently, inhibits autophagy and raises cell proliferation in A-10 cells maintained in high glucose concentration.

  16. Vasopressin activates Akt/mTOR pathway in smooth muscle cells cultured in high glucose concentration

    International Nuclear Information System (INIS)

    Highlights: •AVP induces mTOR phosphorylation in A-10 cells cultured in high glucose concentration. •The mTOR phosphorylation is mediated by the PI3K/Akt pathway activation. •The AVP-induced mTOR phosphorylation inhibited autophagy and stimulated cell proliferation. -- Abstract: Mammalian target of rapamycin (mTOR) complex is a key regulator of autophagy, cell growth and proliferation. Here, we studied the effects of arginine vasopressin (AVP) on mTOR activation in vascular smooth muscle cells cultured in high glucose concentration. AVP induced the mTOR phosphorylation in A-10 cells grown in high glucose, in contrast to cells cultured in normal glucose; wherein, only basal phosphorylation was observed. The AVP-induced mTOR phosphorylation was inhibited by a PI3K inhibitor. Moreover, the AVP-induced mTOR activation inhibited autophagy and increased thymidine incorporation in cells grown in high glucose. This increase was abolished by rapamycin which inhibits the mTORC1 complex formation. Our results suggest that AVP stimulates mTOR phosphorylation by activating the PI3K/Akt signaling pathway and, subsequently, inhibits autophagy and raises cell proliferation in A-10 cells maintained in high glucose concentration

  17. Paradoxical Effect of Caspofungin: Reduced Activity against Candida albicans at High Drug Concentrations

    OpenAIRE

    Stevens, David A.; Espiritu, Marife; Parmar, Rachana

    2004-01-01

    Resistance problems with caspofungin, an echinocandin inhibitor of fungal cell wall glucan synthesis, have been rare. We noted paradoxical turbid growth of Candida albicans isolates in broth in some high (supra-MIC) concentrations. Among isolates submitted for susceptibility testing and screened at drug concentrations up to 12.5 ?g/ml, the frequency was 16%. Analysis of the turbid growth indicated slowing of growth in the presence of drug but with numbers of CFU up to 72% those of drug-free ...

  18. RADIOACTIVE HIGH LEVEL WASTE TANK PITTING PREDICTIONS: AN INVESTIGATION INTO CRITICAL SOLUTION CONCENTRATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, E.

    2012-11-08

    A series of cyclic potentiodynamic polarization tests was performed on samples of ASTM A537 carbon steel in support of a probability-based approach to evaluate the effect of chloride and sulfate on corrosion the steel?s susceptibility to pitting corrosion. Testing solutions were chosen to systemically evaluate the influence of the secondary aggressive species, chloride, and sulfate, in the nitrate based, high-level wastes. The results suggest that evaluating the combined effect of all aggressive species, nitrate, chloride, and sulfate, provides a consistent response for determining corrosion susceptibility. The results of this work emphasize the importance for not only nitrate concentration limits, but also chloride and sulfate concentration limits.

  19. Concentration- and pH-dependence of highly alkaline sodium silicate solutions.

    Science.gov (United States)

    Nordström, Jonas; Nilsson, Erik; Jarvol, Patrik; Nayeri, Moheb; Palmqvist, Anders; Bergenholtz, Johan; Matic, Aleksandar

    2011-04-01

    In this study two routes for the gelation of water glass have been investigated; the destabilization by a change in pH and by an increase in concentration through evaporation. Both methods produce optically transparent, highly viscous, homogeneous solutions. The structure and dynamics of the solutions along the two routes have been investigated with dynamic light scattering, (29)Si-Nuclear Magnetic Resonance spectroscopy, viscosity measurements and infrared spectroscopy. We find that the two routes are fundamentally different. Increasing the concentration of the sodium silicate system leaves the silica speciation apparently unchanged. Lowering the pH leads to condensation reactions, thus a change in the silica speciation. PMID:21272893

  20. Production of highly concentrated, heat stable hepatitis B surface antigen in maize

    OpenAIRE

    Hayden, Celine A.; Egelkrout, Erin M.; Moscoso, Alessa M.; Enrique, Cristina; Keener, Todd K.; Jimenez-flores, Rafael; Wong, Jeffrey C.; Howard, John A.

    2012-01-01

    Plant-based oral vaccines are a promising emergent technology that could help alleviate disease burden worldwide by providing a low-cost, heat stable, oral alternative to parenterally administered commercial vaccines. Here we describe high-level accumulation of the hepatitis B surface antigen (HBsAg) at a mean concentration of 0.51%TSP in maize T1 seeds using an improved version of the globulin1 promoter. This concentration is more than four-fold higher than any previously reported lines. HBs...

  1. High concentrations of cadmium, cerium and lanthanum in indoor air due to environmental tobacco smoke

    International Nuclear Information System (INIS)

    Background: Environmental tobacco smoke (ETS) is one of the most important sources for indoor air pollution and a substantial threat to human health, but data on the concentrations of the trace metals cerium (Ce) and lanthanum (La) in context with ETS exposure are scarce. Therefore the aim of our study was to quantify Ce and La concentrations in indoor air with high ETS load. Methods: In two subsequent investigations Ce, La and cadmium (Cd) in 3 smokers' (11 samples) and 7 non-smokers' (28 samples) households as well as in 28 hospitality venues in Southern Germany were analysed. Active sampling of indoor air was conducted continuously for seven days in every season in the smokers' and non-smokers' residences, and for 4 h during the main visiting hours in the hospitality venues (restaurants, pubs, and discotheques). Results: In terms of residences median levels of Cd were 0.1 ng/m3 for non-smokers' and 0.8 ng/m3 for smokers' households. Median concentrations of Ce were 0.4 ng/m3 and 9.6 ng/m3, and median concentrations of La were 0.2 ng/m3 and 5.9 ng/m3 for non-smokers' and for smokers' households, respectively. In the different types of hospitality venues median levels ranged from 2.6 to 9.7 ng/m3 for Cd, from 18.5 to 50.0 ng/m3 for Ce and from 10.6 to 23.0 ng/m3 for La with highest median levels in discotheques. Conclusions: The high concentrations of Ce and La found in high concentrations of Ce and La found in ETS enriched indoor air of smokers' households and hospitality venues are an important finding as Ce and La are associated with adverse health effects and data on this issue are scarce. Further research on their toxicological, human and public health consequences is urgently required. - Highlights: ? We quantified cer, lanthanum and cadmium concentrations in indoor air. ? Cer and lanthanum concentrations were high in tobacco smoke enriched locations. ? Both elements can be considered as good markers for indoor air quality.

  2. Investigations into corrosion of metallic materials in highly concentrated boiling salt solutions

    Energy Technology Data Exchange (ETDEWEB)

    Engell, H.J.; Streckel, H.

    1988-11-01

    Containers for the disposal of radioactive waste in carnallite formations can be exposed to corrosion by highly concentrated hot salt solutions. Previous investigations of the corrosion resistance of candidate materials have been supplemented by measurements of the current density-potential curves of iron-silicon, cobalt-silicon, titanium-nickel and nickel-molybdenum alloys and of tantal. The electrolyte was a concentrated MgCl/sub 2/-NaCl-KCl-MgSO/sub 4/ solution at its boiling point of 170/sup 0/C. The measurements give useful information on the stability of the corrosion resistance of these materials.

  3. Investigations into corrosion of metallic materials in highly concentrated boiling salt solutions

    International Nuclear Information System (INIS)

    Containers for the disposal of radioactive waste in carnallite formations can be exposed to corrosion by highly concentrated hot salt solutions. Previous investigations of the corrosion resistance of candidate materials have been supplemented by measurements of the current density-potential curves of iron-silicon, cobalt-silicon, titanium-nickel and nickel-molybdenum alloys and of tantal. The electrolyte was a concentrated MgCl2-NaCl-KCl-MgSO4 solution at its boiling point of 1700C. The measurements give useful information on the stability of the corrosion resistance of these materials. (orig.)

  4. High Er3+ concentration low refractive index fluorophosphate glass for evanescent wave optical amplifiers

    International Nuclear Information System (INIS)

    This is about the first reported laser glass with very low nD, high Er3+ concentration and no quenching. In this work, a series of high Er3+ concentration (10.6-12.2x1020 ions/cm3), low refractive index (n1550<1.47) and relatively high fluorescence lifetime (6.8-12.6 ms) fluorophosphate glasses were made. A cw-pumping evanescent wave optical amplifier experiment was performed with it, and a relative gain of around 2 dB at 1550 nm wavelength was achieved while the noise level was almost unchanged. To our knowledge, this is the first successful relative gain in evanescent wave optical amplifiers (EWOA) demonstrated with cw pumping. It is a valuable study of specially designed fluorophosphate glass suitable for EWOA communication experiment

  5. High Er{sup 3+} concentration low refractive index fluorophosphate glass for evanescent wave optical amplifiers

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Liyan [Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, Shanghai 201800 (China); Institute of Optoelectronic Materials and Devices, School of Information Engineering, China Jiliang University, Hangzhou 310018 (China)], E-mail: jndxzly@hotmail.com; Chen Nankuang [Institute of Optoelectronic Materials and Devices, School of Information Engineering, China Jiliang University, Hangzhou 310018 (China); Hu Lili [Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, Shanghai 201800 (China)

    2008-10-01

    This is about the first reported laser glass with very low n{sub D}, high Er{sup 3+} concentration and no quenching. In this work, a series of high Er{sup 3+} concentration (10.6-12.2x10{sup 20} ions/cm{sup 3}), low refractive index (n{sub 1550}<1.47) and relatively high fluorescence lifetime (6.8-12.6 ms) fluorophosphate glasses were made. A cw-pumping evanescent wave optical amplifier experiment was performed with it, and a relative gain of around 2 dB at 1550 nm wavelength was achieved while the noise level was almost unchanged. To our knowledge, this is the first successful relative gain in evanescent wave optical amplifiers (EWOA) demonstrated with cw pumping. It is a valuable study of specially designed fluorophosphate glass suitable for EWOA communication experiment.

  6. The role of silicon interstitials in the deactivation and reactivation of high concentration boron profiles

    International Nuclear Information System (INIS)

    Boron cluster formation and dissolution in high concentration B profiles and the role of Si interstitials in these processes are analyzed by kinetic non-lattice Monte Carlo atomistic simulations. For this purpose, we use theoretical structures as simplifications of boron implants into preamorphized Si, followed by low-temperature solid phase epitaxial (SPE) regrowth or laser thermal annealing process. We observe that in the presence of high B concentrations (above 1020 cm-3), significant deactivation occurs during high temperature anneal, even in the presence of only equilibrium Si interstitials. The presence of additional Si interstitials from an end of range (EOR) damage region accelerates the deactivation process and makes B deactivation slightly higher. We show that B deactivation and reactivation processes can be clearly correlated to the evolution of Si interstitial defects at the EOR. The minimum level of activation occurs when the Si interstitial defects at EOR dissolve or form very stable defects

  7. Regimes of resonance Raman utility: studies in diluted liquid benzene

    Science.gov (United States)

    Chadwick, Christopher; Hallen, Hans; Willitsford, Adam; Philbrick, C. Russell

    2008-10-01

    Resonance Raman yields huge increases in cross section as the excitation laser is tuned through an absorption band. Unfortunately, the measured signal levels do not always correspondingly increase. We use a tunable laser source to investigate this phenomenon with three different concentrations of liquid benzene in heptane as well as pure liquid benzene. Resonant Raman signal enhancement of the ring-breathing mode (992,m-1) has been confirmed. Additionally, species absorption limitations on this enhancement has been identified. Two different regimes have been identified where resonance Raman can be applied to enable spectrographic information where the signal level of non-resonant Raman is not measurable. While Raman scattering intensities are largely dependent on the number of scattering agents in the non-resonant case, when probing electronic absorption features in a species with the excitation light, enhancement yields a significant signal output even as the number of scattering agents is reduced. The enhancement gains of the signal to noise for resonant probing are superior in low concentrations and tiny interaction volumes. This enhancement characteristic has broad application for materials identification in trace species such as remote sensing and tiny sampling volumes such as near-field optical microscopy.

  8. Picosecond pulse radiolysis of direct and indirect radiolytic effects in highly concentrated halide aqueous solutions.

    Science.gov (United States)

    Balcerzyk, Anna; Schmidhammer, Uli; El Omar, Abdel Karim; Jeunesse, Pierre; Larbre, Jean-Philippe; Mostafavi, Mehran

    2011-08-25

    Recently we measured the amount of the single product, Br(3)(-), of steady-state radiolysis of highly concentrated Br(-) aqueous solutions, and we showed the effect of the direct ionization of Br(-) on the yield of Br(3)(-). Here, we report the first picosecond pulse-probe radiolysis measurements of ionization of highly concentrated Br(-) and Cl(-) aqueous solutions to describe the oxidation mechanism of the halide anions. The transient absorption spectra are reported from 350 to 750 nm on the picosecond range for halide solutions at different concentrations. In the highly concentrated halide solutions, we observed that, due to the presence of Na(+), the absorption band of the solvated electron is shifted to shorter wavelengths, but its decay, taking place during the spur reactions, is not affected within the first 4 ns. The kinetic measurements in the UV reveal the direct ionization of halide ions. The analysis of pulse-probe measurements show that after the electron pulse, the main reactions in solutions containing 1 M of Cl(-) and 2 M of Br(-) are the formation of ClOH(-•) and BrOH(-•), respectively. In contrast, in highly concentrated halide solutions, containing 5 M of Cl(-) and 6 M of Br(-), mainly Cl(2)(-•) and Br(2)(-•) are formed within the electron pulse without formation of ClOH(-•) and BrOH(-•). The results suggest that, not only Br(-) and Cl(-) are directly ionized into Br(•) and Cl(•) by the electron pulse, the halide atoms can also be rapidly generated through the reactions initiated by excitation and ionization of water, such as the prompt oxidation by the hole, H(2)O(+•), generated in the coordination sphere of the anion. PMID:21770462

  9. High concentration Brownian coagulation in jet flow using two enhancement formulations

    Directory of Open Access Journals (Sweden)

    Lin Pei-Feng

    2012-01-01

    Full Text Available Ultra-fine particle coagulation by Brownian motion at high concentration in planar jet flow is simulated. A Taylor-Series Expansion Method of Moments is employed to solve the particle general dynamic equation. The volume fraction gets high value, very closes to that at the nozzle exit. As the vortex pairing develops, the high volume fraction region rolls out and mixes with the low value region. The enhancement factor given by Trzeciak et al. will be less than one at some specific outer positions, which seems to be less accurate than the one given by Heine et al.

  10. THE INFLUENCE OF BENZENE AS A TRACE REACTANT IN TITAN AEROSOL ANALOGS

    Energy Technology Data Exchange (ETDEWEB)

    Trainer, Melissa G. [Planetary Environments Laboratory, Code 699, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Sebree, Joshua A. [NASA Postdoctoral Program Fellow, Code 699, Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Heidi Yoon, Y.; Tolbert, Margaret A., E-mail: melissa.trainer@nasa.gov [Cooperative Institute for Research in Environmental Sciences, University of Colorado at Boulder, Box 216 UCB, Boulder, CO 80309 (United States)

    2013-03-20

    Benzene has been detected in Titan's atmosphere by Cassini instruments, with concentrations ranging from sub-ppb in the stratosphere to ppm in the ionosphere. Sustained levels of benzene in the haze formation region could signify that it is an important reactant in the formation of Titan's organic aerosol. To date, there have not been laboratory investigations to assess the influence of benzene on aerosol properties. We report a laboratory study on the chemical composition of organic aerosol formed from C{sub 6}H{sub 6}/CH{sub 4}/N{sub 2} via far ultraviolet irradiation (120-200 nm). The compositional results are compared to those from aerosol generated by a more ''traditional Titan'' mixture of CH{sub 4}/N{sub 2}. Our results show that even a trace amount of C{sub 6}H{sub 6} (10 ppm) has significant impact on the chemical composition and production rates of organic aerosol. There are several pathways by which photolyzed benzene may react to form larger molecules, both with and without the presence of CH{sub 4}, but many of these reaction mechanisms are only beginning to be explored for the conditions at Titan. Continued work investigating the influence of benzene in aerosol growth will advance understanding of this previously unstudied reaction system.

  11. Low level detection of Benzene in Food Grade Hexane by Ultraviolet Spectrophotometry.

    Science.gov (United States)

    Emmandi, R; Sastry, M I S; Patel, M B

    2014-10-15

    A simple, sensitive, and accurate Ultraviolet Spectrophotometric method has been developed and validated for the determination of Benzene in Food Grade Hexane. Benzene in spectroscopic grade Hexane shows vibrational fine structure having four well resolved peaks. In the wavelength range 240-270nm, peak at 255nm is considered for the method development. Beer's law was obeyed in the concentration range of 0.6-10.0?LL(-1), with correlation coefficient, 0.9999, detection limit 0.2?LL(-1) and quantitation limit 0.6?LL(-1) are established. Percentage recovery studies showed that the method was not affected by the presence of other solvents having the similar boiling range with Hexane. The method was validated by determining its accuracy and precision which proves suitability of the developed method for the routine determination of Benzene in Food Grade Hexane. The proposed method has been applied successfully for the analysis of the Food Grade Hexane. PMID:24837938

  12. Neutron investigations of magnetite-oleic acid-benzene ferrofluids stability with the excess of surfactant

    International Nuclear Information System (INIS)

    Magnetite-oleic acid-benzene magnetic fluid with the excess of oleic acid was studied by small-angle neutron scattering. Pure solutions of oleic acid in benzene were also investigated to reveal a possible micelle formation of molecules. It was shown that oleic acid does not form micelles in the investigated range of concentration. the results of experiment indicate that the surfactant excess (smaller than 25% volume fraction) does not lead to any observable aggregation of the magnetic particles. At the same time a bigger attraction between free molecules of surfactant in the ferrofluids in comparison with solutions of oleic acid in benzene is observed. A dramatic breaking of the stability occurs and it leads to the aggregation of magnetic particles if the excess of surfactant is bigger than 25%.

  13. Effects of high glucose and high insulin concentrations on osteoblast function in vitro.

    Science.gov (United States)

    Cunha, Juliana S; Ferreira, Vanessa M; Maquigussa, Edgar; Naves, Marcelo A; Boim, Mirian A

    2014-10-01

    Bone disease as a consequence of diabetes mellitus (DM) is not fully understood. The effects of high glucose (30 mM), high insulin (50 nM), or mannitol (30 mM; osmotic control) were evaluated on MC3T3-E1 cells (osteoblasts) in vitro. The mRNA and protein levels of parathyroid hormone (PTH) receptor (PTH1R), collagen I, RANKL, osteoprotegerin (OPG), alkaline phosphatase (ALP), and glucose transporter (GLUT1) were estimated by real-time polymerase chain reaction or Western blotting. The mineralization capacity was analyzed by von Kossa staining. High glucose induced overexpression of RANKL (2×) and OPG (30×), suggesting that RANKL-induced osteoclast activity might not be a dominant mechanism of bone disease in DM, since this increase was followed by increased OPG. Collagen I increased by 12×, indicating an excess of organic matrix production. The expression of ALP decreased by 50%, indicating a deficit in mineralization capacity, confirmed by von Kossa staining. Mannitol induced similar effects as glucose suggesting that extracellular hyperosmolarity was able to stimulate organic matrix production. GLUT1 expression was not altered, and insulin did not reverse most of the effects of glucose, suggesting that glucose uptake by osteoblasts was not altered by high glucose. The data suggest that the bone fragility typical of DM is not a consequence of excessive bone reabsorption but is instead attributable to a defect in organic matrix mineralization. The heightened increase in OPG versus RANKL might cause a decrease in the bone-remodeling cycle. Osteoblasts appear to be more sensitive to extracellular hypertonicity than to the intracellular metabolic effects of hyperglycemia. PMID:24859221

  14. Impact of High Concentration Solutions on Hydraulic Properties of Geosynthetic Clay Liner Materials

    Directory of Open Access Journals (Sweden)

    Lei Liu

    2012-11-01

    Full Text Available This study focuses on the impact of landfill high concentration solutions erosion on geosynthetic clay liner (GCL materials permeability. The permeation tests on the GCL, submerged using different kinds of solutions with different concentrations, were carried out systematically by taking these chemical solutions as permeant liquids. Based on seasonal variations of ion concentrations in Chenjiachong landfill leachate (Wuhan Province, CaCl2, MgCl2, NaCl, and KCl were selected as chemical attack solutions to carry out experimental investigations under three concentrations (50 mM, 100 mM, 200 mM and soak times (5, 10, and 20 days. The variation law of the GCL hydraulic conductivity under different operating conditions was analyzed. The relationship between GCL hydraulic conductivity, chemical solutions categories, concentrations, and soak times were further discussed. The GCL hydraulic conductivity, when soaked and permeated with high concentration chemical solutions, increases several times or exceeds two orders of magnitude, as compared with the permeation test under normal conditions that used water as the permeant liquid. This reveals that GCL is very susceptible to chemical attack. For four chemical solutions, the chemical attack effect on GCL hydraulic conductivity is CaCl2 > MgCl2 > KCl > NaCl. The impact of soak times on GCL hydraulic conductivity is the cooperative contribution of the liner chemical attack reaction and hydration swelling. A longer soak time results in a more advantageous hydration swelling effect. The chemical attack reaction restrains the hydration swelling of the GCL. Moreover, the GCL hydraulic conductivity exponentially decreases with the increased amplitude of thickness.

  15. Factors affecting biotic mercury concentrations and biomagnification through lake food webs in the Canadian high Arctic.

    Science.gov (United States)

    Lescord, Gretchen L; Kidd, Karen A; Kirk, Jane L; O'Driscoll, Nelson J; Wang, Xiaowa; Muir, Derek C G

    2015-03-15

    In temperate regions of Canada, mercury (Hg) concentrations in biota and the magnitude of Hg biomagnification through food webs vary between neighboring lakes and are related to water chemistry variables and physical lake features. However, few studies have examined factors affecting the variable Hg concentrations in landlocked Arctic char (Salvelinus alpinus) or the biomagnification of Hg through their food webs. We estimated the food web structure of six high Arctic lakes near Resolute Bay, Nunavut, Canada, using stable carbon (?(13)C) and nitrogen (?(15)N) isotopes and measured Hg (total Hg (THg) in char, the only fish species, and methylmercury (MeHg) in chironomids and zooplankton) concentrations in biota collected in 2010 and 2011. Across lakes, ?(13)C showed that benthic carbon (chironomids) was the dominant food source for char. Regression models of log Hg versus ?(15)N (of char and benthic invertebrates) showed positive and significant slopes, indicting Hg biomagnification in all lakes, and higher slopes in some lakes than others. However, no principal components (PC) generated using all water chemistry data and physical characteristics of the lakes predicted the different slopes. The PC dominated by aqueous ions was a negative predictor of MeHg concentrations in chironomids, suggesting that water chemistry affects Hg bioavailability and MeHg concentrations in these lower-trophic-level organisms. Furthermore, regression intercepts were predicted by the PCs dominated by catchment area, aqueous ions, and MeHg. Weaker relationships were also found between THg in small char or MeHg in pelagic invertebrates and the PCs dominated by catchment area, and aqueous nitrate and MeHg. Results from these high Arctic lakes suggest that Hg biomagnification differs between systems and that their physical and chemical characteristics affect Hg concentrations in lower-trophic-level biota. PMID:24909711

  16. Benzene partial hydrogenation: advances and perspectives.

    Science.gov (United States)

    Foppa, Lucas; Dupont, Jairton

    2015-04-01

    The partial hydrogenation of benzene to cyclohexene is an economically interesting and technically challenging reaction. Over the last four decades, a lot of work has been dedicated to the development of an exploitable process and several approaches have been investigated. However, environmental constraints often represent a limit to their industrial application, making further research in this field necessary. The goal of this review is to highlight the main findings of the different disciplines involved in understanding the governing principles of this reaction from a sustainable chemistry standpoint. Special emphasis is given to ruthenium-catalyzed liquid phase batch hydrogenation of benzene. PMID:25588547

  17. 40 CFR 80.1220 - What are the implementation dates for the gasoline benzene program?

    Science.gov (United States)

    2010-07-01

    ...the implementation dates for the gasoline benzene program? 80.1220 Section 80.1220...OF FUELS AND FUEL ADDITIVES Gasoline Benzene General Information § 80.1220 ...the implementation dates for the gasoline benzene program? (a) Benzene...

  18. Lower Salinomycin Concentration Increases Apoptotic Detachment in High-Density Cancer Cells

    Directory of Open Access Journals (Sweden)

    Sungpil Yoon

    2012-10-01

    Full Text Available The present study identified a novel salinomycin (Sal sensitization mechanism in cancer. We tested whether Sal reduced proliferation in a high-density population by counting attached cell numbers after Sal treatment. Sal reduced proliferation in high-density cell populations. Longer exposure to Sal further reduced proliferation. Sal concentrations of 0.1 and 5 ?M had similar sensitization effects, suggesting that Sal toxicity was minimal with longer exposure to a high-density cell population. The results suggest that Sal can be applied at a relatively low concentration for a longer time to overcome drug-resistant solid tumors. The 0.5 ?M Sal treatment resulted in fewer attached cells than that of the 5 ?M Sal treatment with a longer exposure. The lower Sal concentration mainly increased the number of easily detachable cells on the surface. In particular, 0.5 ?M Sal increased cellular detachment of newly produced daughter cells. The easily-detachable cells were undergoing apoptosis. It seems that the 0.5 ?M Sal treatment also increased cellular toxicity. These novel findings may contribute to the development of Sal-based therapy for patients with drug-resistant cancer or a high-density solid tumor.

  19. Anaerobic biotransformation of high concentrations of chloroform by an enrichment culture and two bacterial isolates.

    Science.gov (United States)

    Shan, Huifeng; Kurtz, Harry D; Mykytczuk, Nadia; Trevors, Jack T; Freedman, David L

    2010-10-01

    A fermentative enrichment culture (designated DHM-1) was developed that is capable of cometabolically biotransforming high concentrations of chloroform (CF) to nontoxic end products. Two Pantoea spp. were isolated from DHM-1 that also possess this dechlorination capability. Following acclimation to increasing levels of CF, corn syrup-grown DHM-1 was able to transform over 500 mg/liter CF in the presence of vitamin B(12) (approximately 3% of CF on a molar basis) at a rate as high as 22 mg/liter/day in a mineral salts medium. CO, CO(2), and organic acids were the predominant biodegradation products, suggesting that hydrolytic reactions predominate during CF transformation. DHM-1 was capable of growing on corn syrup in the presence of high concentrations of CF (as may be present near contaminant source zones in groundwater), which makes it a promising culture for bioaugmentation. Strains DHM-1B and DHM-1T transform CF at rates similar to that of the DHM-1 enrichment culture. The ability of these strains to grow in the presence of high concentrations of CF appears to be related to alteration of membrane fluidity or homeoviscous and homeophasic adaptation. PMID:20693443

  20. Anaerobic Biotransformation of High Concentrations of Chloroform by an Enrichment Culture and Two Bacterial Isolates ? †

    Science.gov (United States)

    Shan, Huifeng; Kurtz, Harry D.; Mykytczuk, Nadia; Trevors, Jack T.; Freedman, David L.

    2010-01-01

    A fermentative enrichment culture (designated DHM-1) was developed that is capable of cometabolically biotransforming high concentrations of chloroform (CF) to nontoxic end products. Two Pantoea spp. were isolated from DHM-1 that also possess this dechlorination capability. Following acclimation to increasing levels of CF, corn syrup-grown DHM-1 was able to transform over 500 mg/liter CF in the presence of vitamin B12 (approximately 3% of CF on a molar basis) at a rate as high as 22 mg/liter/day in a mineral salts medium. CO, CO2, and organic acids were the predominant biodegradation products, suggesting that hydrolytic reactions predominate during CF transformation. DHM-1 was capable of growing on corn syrup in the presence of high concentrations of CF (as may be present near contaminant source zones in groundwater), which makes it a promising culture for bioaugmentation. Strains DHM-1B and DHM-1T transform CF at rates similar to that of the DHM-1 enrichment culture. The ability of these strains to grow in the presence of high concentrations of CF appears to be related to alteration of membrane fluidity or homeoviscous and homeophasic adaptation. PMID:20693443

  1. Electrodeposited ZnO/ Zn Photo catalysts for the Degradation of Benzene-Toluene-Xylene Mixture in Aqueous Phase

    International Nuclear Information System (INIS)

    The recognition of the ability of volatile organic compounds, (VOCs) to pollute the ground water is now well documented. VOCs such as benzene, toluene and xylene from the petroleum industries processed water leaked through the underground old piping system into the soils and groundwater during its transportation to the wastewater plant. Photo catalysis have been used as a potential system in the degradation of VOCs in the wastewater. However, the powdered form photo catalysts that were used in various studies are difficult to be separated from the aqueous solution at the end of the treatment. Therefore, the main objective of this research is to prepare the electrodeposited photo catalysts for the degradation of aromatic hydrocarbon mixture, benzene-toluene-xylene (BTX) solution under UV light (354 nm). The concentrations of electrolyte and electrodeposition voltages used to prepare the photo catalysts were studied for their efficiency in the degradation. From the research, ZnO/ Zn prepared in 0.8 M NaOH and under 12 V possessed the best catalytic degradation performance by degrading 32.37 % of BTX in the solution. The ZnO/ Zn photo catalyst was characterized using X-ray Diffraction Techniques (XRD) which illustrated high crystallinity of Zn species and reasonably high amorphous phase of ZnO species. (author)

  2. Optical and thermal performance predictions for a high concentration point focus photovoltaic system

    Energy Technology Data Exchange (ETDEWEB)

    Mallick, Tapas K.; Eames, Philip C. [University of Warwick (United Kingdom). Institute for Sustainable Energy and Resources School of Engineering

    2008-07-01

    The optical and thermal behaviour of a high concentration point focus Fresnel lens based photovoltaic concentrator system with the potential for large scale power generation in regions with predominantly direct radiation has been investigated. A ray projection technique was used to evaluate the energy capture of the concentrator when located at Denver (39 45{sup '}N, 105 W), USA, predictions of temperature at different sections of the concentrator using a three-dimensional finite difference model have also been made. The beam radiation normal to the concentrator aperture for the tracking approach used with no self shading was calculated to be 1778 kWh m{sup -2} year{sup -1} for the collector located in Denver. For inter trough spacing of 160mm the predicted self shading loss was 14.8%, this reduced to 6.6% when the inter trough spacing was increased to 360mm. For the collector with inter trough spacing of 160mm, when the inter collector spacing of the concentrator increased from 1m to 2m, the predicted annual energy collection for the concentrator increased by 25%, however, further increase of inter-collector spacing had little effect on the energy capture by the collector. Using the three-dimensional finite difference model the temperatures within the collector and at the PV cell have been predicted. The predicted cell temperature reduced from 58.23 C to 48.86 C when the fin thickness increased from 0.2mm to 0.5mm for an illumination of 75 Suns. Increasing fin length from 50mm to 100mm had little effect on the predicted cell temperatures. (orig.)

  3. 4-(3-Methyl­benzene­sulfonamido)­phenyl 3-methyl­benzene­sulfonate

    OpenAIRE

    Al-najjar, Belal O.; Tengku Muhammad, Tengku Sifzizul; Wahab, Habibah A.; Rosli, Mohd Mustaqim; Fun, Hoong-kun

    2012-01-01

    The complete mol­ecule of the title compound, C20H19NO5S2, is generated by a crystallographic twofold axis and the O atom and N—H group attached to the central benzene ring are statistically disordered. The dihedral angle between the central and terminal benzene rings is 56.91?(5)° and that between the terminal benzene rings is 29.80?(5)°. In the crystal, N—H?O hydrogen bonding links the mol­ecules into sheets lying parallel to the ab plane.

  4. 4-(3-Methyl-benzene-sulfonamido)-phenyl 3-methyl-benzene-sulfonate.

    Science.gov (United States)

    Al-Najjar, Belal O; Tengku Muhammad, Tengku Sifzizul; Wahab, Habibah A; Rosli, Mohd Mustaqim; Fun, Hoong-Kun

    2012-02-01

    The complete mol-ecule of the title compound, C(20)H(19)NO(5)S(2), is generated by a crystallographic twofold axis and the O atom and N-H group attached to the central benzene ring are statistically disordered. The dihedral angle between the central and terminal benzene rings is 56.91?(5)° and that between the terminal benzene rings is 29.80?(5)°. In the crystal, N-H?O hydrogen bonding links the mol-ecules into sheets lying parallel to the ab plane. PMID:22346904

  5. Removal of High Concentration of Phenol from Synthetic Solutions by Fusarium Culmorum Granules

    Directory of Open Access Journals (Sweden)

    Sh. Roudbar Mohammadi

    2012-03-01

    Full Text Available Background and Objectives: Effluent generated in several industries contains phenolic compounds, which have been classified as priority pollutants. Due to its toxicity, the conventional systems are inefficient for treatment of phenol-Laden wastewater. Biological processes using pure microbial culture, including fungi and yeast, are environmentally friendly techniques capable of complete destruction of contaminants. Materials and Methods: This work was aimed at investigating the efficiency of a fungi specie in the decomposition of high concentrations of phenol ranging from 500 to 20000 mg/L. Several batch reactors were operated at different phenol concentration. The concentration of residual phenol was monitored over time using colorimetric method 4-aminoantipyrine. The removal efficiency was calculated considering the initial phenol concentration. Results: Experimental data indicated that the phenol could efficiently degrade using the selected culture. The developed granules could completely degrade phenol at concentrations up to 20000 mg/L. Conclusion: It can be concluded from the experimental data that the biodegradation using the Fungi granules is a very efficient and thus promising technique for treatment of wastewaters containing phenolic compounds.

  6. The occurrence of high concentration of natural radionuclides in black sands of Malaysian beaches

    International Nuclear Information System (INIS)

    A study has been carried out to measure the concentration of natural radionuclides in black sands of Pasir Hitam (Langkawi Island) and Batu Feringhi (Penang Island) beaches of Malaysia. Black sand was found to be more concentrated in the beach of Pasir Hitam as compared to Batu Feringhi where it occurred only in patches. Sample analysis was conducted using a gamma spectrometer. This study showed that most of black sands of Pasir Hitam beach and some of Batu Feringhi beach contain high concentrations of natural radionuclides of the uranium and thorium series. The mean concentrations of radium-226 and radium-228 in black sand of Pasir Hitam beach were 1150 ± 800 Bq/kg and 500 ± 300 Bq/kg respectively. This is much higher than the normal beach sands with activity levels of 13 ± 7 Bq/kg Ra-226 and 11 ±6 Bq/kg Ra-228. The mean concentrations of 1350 ± 1300 Bq/kg Ra-226 and 805 ± 757 Bq/kg Ra-228 of two black sans samples of Batu Feringhi beach were similar to those of the Pasir Hitam. However, some black sand mixtures of Batu Feringhi contain normal level of natural radionuclides. In general, the activity levels of natural radionuclides in black sand of Malaysian beaches vary very significantly. (Author)

  7. High variability of dissolved iron concentrations in the vicinity of Kerguelen Island (Southern Ocean)

    Science.gov (United States)

    Quéroué, F.; Sarthou, G.; Planquette, H. F.; Bucciarelli, E.; Chever, F.; van der Merwe, P.; Lannuzel, D.; Townsend, A. T.; Cheize, M.; Blain, S.; d'Ovidio, F.; Bowie, A. R.

    2015-01-01

    Dissolved Fe (dFe) concentrations were measured in the upper 1300 m of the water column in the vicinity of Kerguelen Island as part of the second Kerguelen Ocean Plateau compared Study (KEOPS2). Concentrations ranged from 0.06 nmol L-1 in offshore, Southern Ocean waters, to 3.82 nmol L-1 within Hillsborough Bay, on the north-eastern coast of Kerguelen Island. Direct island runoff, glacial melting and resuspended sediments were identified as important inputs of dFe that could potentially fertilize the northern part of the plateau. A significant deep dFe enrichment was observed over the plateau with dFe concentrations increasing up to 1.30 nmol L-1 close to the seafloor, probably due to sediment resuspension and pore water release. Biological uptake was identified as a likely explanation for the decrease in dFe concentrations between two visits (28 days apart) at a station above the plateau. Our results allowed studying other processes and sources, such as atmospheric inputs, lateral advection of enriched seawater, remineralization processes and the influence of the Polar Front (PF) as a vector for Fe transport. Overall, heterogeneous sources of Fe over and off the Kerguelen Plateau, in addition to strong variability in Fe supply by vertical or horizontal transport, may explain the high variability in dFe concentrations observed during this study.

  8. High variability of dissolved iron concentrations in the vicinity of Kerguelen Island (Southern Ocean

    Directory of Open Access Journals (Sweden)

    F. Quéroué

    2015-01-01

    Full Text Available Dissolved Fe (dFe concentrations were measured in the upper 1300 m of the water column in the vicinity of Kerguelen Island as part of the second Kerguelen Ocean Plateau compared Study (KEOPS2. Concentrations ranged from 0.06 nmol L?1 in offshore, Southern Ocean waters, to 3.82 nmol L?1 within Hillsborough Bay, on the north-eastern coast of Kerguelen Island. Direct island runoff, glacial melting and resuspended sediments were identified as important inputs of dFe that could potentially fertilize the northern part of the plateau. A significant deep dFe enrichment was observed over the plateau with dFe concentrations increasing up to 1.30 nmol L?1 close to the seafloor, probably due to sediment resuspension and pore water release. Biological uptake was identified as a likely explanation for the decrease in dFe concentrations between two visits (28 days apart at a station above the plateau. Our results allowed studying other processes and sources, such as atmospheric inputs, lateral advection of enriched seawater, remineralization processes and the influence of the Polar Front (PF as a vector for Fe transport. Overall, heterogeneous sources of Fe over and off the Kerguelen Plateau, in addition to strong variability in Fe supply by vertical or horizontal transport, may explain the high variability in dFe concentrations observed during this study.

  9. Domestic wastewater reclamation by submerged membrane bioreactor with high concentration powdered activated carbon for stream restoration.

    Science.gov (United States)

    Seo, G T; Ahan, H I; Kim, J T; Lee, Y J; Kim, I S

    2004-01-01

    This study focuses on the practical application of high concentration powdered activated carbon coupled membrane bio-reactor to domestic wastewater reclamation. The study was conducted in three parts, such as analysis of secondary domestic wastewater effluent, design and operation parameter evaluation and reclaimed water quality estimation for stream restoration. The organic concentration was 25.2-80.2 mgCOD(Cr)/L for the effluent of three domestic wastewater treatment plants. Around 50-75% of the COD was low molecular substances less than 1,000 which were quite biodegradable. The sawdust PAC was estimated to be proper adsorbent for the organics in the secondary effluents. Its Freundlich constant, K value was 5.847 and 1/n, 0.36. Using a system consists of single reactor with high concentration PAC (80 g/L) and submerged hollow fiber MF membrane module with nominal pore size of 0.1 microm, design and operation parameters were obtained, such as HRT of the bioreactor (2.5 hr), PAC concentration (80 g/L), the initial flux (less than 0.5 m/day) and intermittent suction cycle (12 min. suction and 3 min. idling). Organic removal by the system was high enough to produce reclaimed water for urban stream restoration The effluent organic concentration was at the level of 2 mg/L in terms of TOC (around 5 mg/L as COD(Cr)). Substances with molecular weight cut off < 1,000 were removed mostly by adsorption and biodegradation. Those above 1,000 were rejected at PAC cake layer on the membrane and gradually degraded by microorganisms during extended contact. PMID:15344788

  10. Consequences of limiting benzene content of motor gasoline

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, E.H.; Conrard, M.C.; Cremer, G.; Hancke, J.; De Roocker, A.

    1983-01-01

    This report considers current motor gasoline benzene levels, related legislation in Western Europe and the consequences of limiting the benzene content of gasoline. The report first reviews the sources of benzene in gasoline and summarises the existing legislation on allowable levels. It then surveys the benzene levels in current motor gasolines and analyses the causes of variations. Means of reducing benzene contents, either by adjusting existing processing routes or by extracting benzene from gasoline blending components, are considered. The impact of benzene limitations on the production of motor gasolines are assessed in terms of the costs involved and the energy penalties incurred. Finally, the report looks at the potential problem of the disposal of extracted benzene. (Copyright (c) CONCAWE Den Haag December 1983.)

  11. High Radon concentration in the karst area of south Puglia, Italy

    Science.gov (United States)

    Taroni, Mattia; Bartolomei, Paolo; Esposito, Massimo; Vaccaro, Carmela

    2010-05-01

    The Radon mapping are normally based on regular grids or on geological maps. The geological maps are advantageous because foresee little areas with high hazard in zones which are otherwise considered like a low risk. The Italian national maps consider the South Puglia, Lecce Karst, as a zone with low risk, but this region presents local important anomalies that can be seen with the geological Radon map. The methodology used to understand the natural phenomena (that are the basis of the analysis of potential Radon risk) is based on a preliminary study from literature: Geological study, general classification, environment formation in which it has developed the area or part of it, detailed studies of the area investigated, the underground structure, level of fracturing, cracking, and primary and secondary porosity, seismic of area. The Area's identification with different risk degrees of Radon production, concentration and emanation characterized by natural boundaries, geological, geomorphological, etc... Information obtained from paragraphs 1 and 2 provide the "Indices of potential risk of the generation, emanation and diffusion of Radon'; this hazard indices allow to optimize the measurements distribution in soils. We Identify the sub-areas of the zone study that can be characterized by high Radon concentrations, dividing these by "natural" hypothetical lines such as the lithology changing, permeability, subsoil structure, etc. ... The preliminary study allows the optimisation of sampling strategy based on not Uniform distribution of 'in situ' measures, where to intensive the measures and where to make only control points of Radon concentration. With these information and with Uranium concentration in samples of different geological formations and Radon measures in water and in soil air we obtained thematic maps and box-plots linking the natural geological indices and we identified the factors that govern the Radon rise and diffusion. The Lecce Karst's study have foreseen: Samples of rocks and soils to determine the Uranium concentration; Collection of water samples for the determination of Radon concentrations; Measurements of the Radon concentration in soil air; The Lecce's area is divided into 4 sub-areas, each of them with the same geological features: subsoil structure with high/normal/low fracturing, cracking, permeability, porosity, ecc... The potential Radon risk increases with the alteration's degree of subsoil structure. Results show that the 4 Lecce's subareas are characterized by average Radon value between 1.000-2.000 Bq/m3, and that in 2 of the 4 zones, characterized by high fracturing and big permeability, the range is high, from 400 Bq/m3 to over the 60.000 Bq/m3. The distribution of anomalies isn't homogeneous in the study zone, but as Hot-Spot and these are present in all sub-areas; the greatest number is detected in areas with high fracturing and cracking and in areas with lithological changes at different permeability. The others determinants factors in these areas are those anthropogenic; in some little zones belonging to subareas there are industrial and commercial areas built removing soil and damaging and altering the subsoil structure; in this way create zones of Radon accumulation in the soil air with fast ascent of the gas to the surface, and this produce high Radon concentration indoor. In the soil around these areas, few meters from buildings, and in the indoor air the Radon concentration is higher than 60.000 Bq/m3.

  12. Lead concentrations in maternal and umbilical cord blood in areas with high and low air pollution.

    Science.gov (United States)

    Dussias, V; Stefos, T; Stefanidis, K; Paraskevaidis, E; Karabini, F; Lolis, D; Vasilios, D; Theodor, S; Konstantinos, S; Evangelos, P; Fotini, K; Dimitrios, L

    1997-01-01

    The lead concentrations in maternal and umbilical cord blood were determined in 50 parturient women at delivery. Twenty-five lived in agricultural areas with low air pollution and 25 lived in urban areas with high air pollution. The mean lead concentrations (mean +/- SD) in maternal and umbilical cord blood and the correlation coefficient of mothers from urban areas with high air pollution were 37.2 +/- 4.7 ng/ml, 20 +/- 3.4 ng/ml and r = 57, respectively. The mean lead concentrations in maternal and umbilical cord blood and the correlation coefficient of mothers from agricultural areas with low air pollution were 20.5 +/- 5.6 ng/ml, 12.9 +/- 3.6 ng/ml and r = 0.70, respectively. Our results show that the difference in mean lead concentration between the blood of mothers both from urban and agricultural areas and the blood from the umbilical cords of their newborns was statistically significant (p < 0.001). The factors that control the transfer of lead from the mother's blood to the fetus are the quantity of the element in the mother's blood and the placenta itself which has a dynamic protective function that is amplified when maternal blood lead levels are raised. PMID:9478314

  13. A modified coaxial electrospinning for preparing fibers from a high concentration polymer solution

    Directory of Open Access Journals (Sweden)

    2011-08-01

    Full Text Available A new process technology modified from conventional coaxial electrospinning process has been developed to prepare polymer fibers from a high concentration solution. This process involves a pure solvent concentrically surrounding polymer fluid in the spinneret. The concentric spinneret was constructed simply by inserting a metal needle through a high elastic silica gel tube. Two syringe pumps were used to drive the core polymer solution and the sheath solvent. Using polyvinylpyrrolidone (PVP as the polymer model, which normally has an electrospinnable concentration of 10% w/v in ethanol, it was possible to electrospin 35% w/v of PVP in the same solvent, when pure N, N-dimethylacetamide (DMAc was used as sheath fluid. The resultant fibers have a smooth surface morphology and good structural uniformity. The diameter of the fibers was 2.0±0.25 µm when the DMAc-to-polymer-solution flow rate ratio was set as 0.1. The process technology reported here opens a new window to tune the polymer fibers obtained by the electrospinning, and is useful for improving productivity of the electrospinning process.

  14. Continuous Ethanol Production with a Membrane Bioreactor at High Acetic Acid Concentrations

    Directory of Open Access Journals (Sweden)

    Päivi Ylitervo

    2014-07-01

    Full Text Available The release of inhibitory concentrations of acetic acid from lignocellulosic raw materials during hydrolysis is one of the main concerns for 2nd generation ethanol production. The undissociated form of acetic acid can enter the cell by diffusion through the plasma membrane and trigger several toxic effects, such as uncoupling and lowered intracellular pH. The effect of acetic acid on the ethanol production was investigated in continuous cultivations by adding medium containing 2.5 to 20.0 g·L?1 acetic acid at pH 5.0, at a dilution rate of 0.5 h?1. The cultivations were performed at both high (~25 g·L?1 and very high (100–200 g·L?1 yeast concentration by retaining the yeast cells inside the reactor by a cross-flow membrane in a membrane bioreactor. The yeast was able to steadily produce ethanol from 25 g·L?1 sucrose, at volumetric rates of 5–6 g·L?1·h?1 at acetic acid concentrations up to 15.0 g·L?1. However, the yeast continued to produce ethanol also at a concentration of 20 g·L?1 acetic acid but at a declining rate. The study thereby demonstrates the great potential of the membrane bioreactor for improving the robustness of the ethanol production based on lignocellulosic raw materials.

  15. Air ion mobility spectra and concentrations upwind and downwind of overhead AC high voltage power lines

    Science.gov (United States)

    Wright, Matthew D.; Buckley, Alison J.; Matthews, James C.; Shallcross, Dudley E.; Henshaw, Denis L.

    2014-10-01

    Corona ions produced by high-voltage power lines (HVPLs) can alter the nearby electrical environment, potentially increasing aerosol charge levels downwind. However, there is a lack of knowledge concerning the concentration and mobility of ions from AC HVPLs and their dispersion away from the line. We present ion concentration and mobility measurements made near AC HVPLs in South-West England. Examples of typical mobility spectra are shown highlighting features commonly observed. Corona was observed during 33 of 46 measurements, at 9 of 11 sites, with positive or ‘bipolar' (both polarities) ion production commonly seen. Ion production usually increases atmospheric concentrations by only a modest amount, but extreme cases can enhance concentration by an order of magnitude or more. A polarity imbalance is required to increase aerosol charge via ion attachment; this was observed on 15 of 24 days when positive corona was observed, but was not seen for negative ions. Ion mobility was higher downwind compared with upwind for both ion polarities, but the increase was not statistically significant. Future work should focus on identifying and characterising ‘heavy-producing' HVPLs, and obtaining results in conditions which may favour negative ion production e.g. high humidity, inclement weather or during nighttime.

  16. Evidence for elevated emissions from high-latitude wetlands contributing to high atmospheric CH4 concentration in the early Holocene

    Science.gov (United States)

    Yu, Zicheng; Loisel, Julie; Turetsky, Merritt R.; Cai, Shanshan; Zhao, Yan; Frolking, Steve; MacDonald, Glen M.; Bubier, Jill L.

    2013-01-01

    The major increase in atmospheric methane (CH4) concentration during the last glacial-interglacial transition provides a useful example for understanding the interactions and feedbacks among Earth's climate, biosphere carbon cycling, and atmospheric chemistry. However, the causes of CH4 doubling during the last deglaciation are still uncertain and debated. Although the ice-core data consistently suggest a dominant contribution from northern high-latitude wetlands in the early Holocene, identifying the actual sources from the ground-based data has been elusive. Here we present data syntheses and a case study from Alaska to demonstrate the importance of northern wetlands in contributing to high atmospheric CH4 concentration in the early Holocene. Our data indicate that new peatland formation as well as peat accumulation in northern high-latitude regions increased more than threefold in the early Holocene in response to climate warming and the availability of new habitat as a result of deglaciation. Furthermore, we show that marshes and wet fens that represent early stages of wetland succession were likely more widespread in the early Holocene. These wetlands are associated with high CH4 emissions due to high primary productivity and the presence of emergent plant species that facilitate CH4 transport to the atmosphere. We argue that early wetland succession and rapid peat accumulation and expansion (not simply initiation) contributed to high CH4 emissions from northern regions, potentially contributing to the sharp rise in atmospheric CH4 at the onset of the Holocene.

  17. First report worldwide of huge retroperitoneal pseudocyst with high fluid concentration of CA 125

    International Nuclear Information System (INIS)

    Background: Primary non-traumatic retroperitoneal pseudocysts are very rare; until now those containing high fluid concentration of CA 125 have not been described. Case Report: A 27-year-old male was admitted to our Department with a symptomatic, huge retroperitoneal cystic lesion of unknown origin. It was totally excised, with surrounding organs left intact. Plasma levels of neoplasm markers were normal; history of trauma, pancreatic and urogenital diseases was denied. The cyst contained transparent fluid with very high concentration of Cancer Antigen 125 (CA 125 > 600 U/ml); cyst fluid culture was negative. Histopathological examination showed absence of an epithelial lining; the wall was composed of dense connective tissue. Thus, diagnosis of retroperitoneal pseudocyst was established. Conclusions: Surgeons should be made aware of the possible occurrence of benign retroperitoneal cystic masses of unknown origin which may have many atypical characteristics, including elevated fluid malignancy markers. (authors)

  18. High Er 3+ concentration low refractive index fluorophosphate glass for evanescent wave optical amplifiers

    Science.gov (United States)

    Zhang, Liyan; Chen, Nan-Kuang; Hu, Lili

    2008-10-01

    This is about the first reported laser glass with very low nD, high Er 3+ concentration and no quenching. In this work, a series of high Er 3+ concentration (10.6-12.2×10 20 ions/cm 3), low refractive index ( n1550fluorophosphate glasses were made. A cw-pumping evanescent wave optical amplifier experiment was performed with it, and a relative gain of around 2 dB at 1550 nm wavelength was achieved while the noise level was almost unchanged. To our knowledge, this is the first successful relative gain in evanescent wave optical amplifiers (EWOA) demonstrated with cw pumping. It is a valuable study of specially designed fluorophosphate glass suitable for EWOA communication experiment.

  19. Spin-lattice relaxation in muscle with high concentrations of Gd-DTPA

    International Nuclear Information System (INIS)

    High concentration of Gd-DTPA in extracellular water causes the intrinsic relaxation rate of water to become shorter than the coupling rate between intra- and extra-cellular water compartments. The fast exchange limit is no longer valid, and distinctly nonexponential spin- lattice recovery should be observed. In this study, striated muscle from Fisher rats is immersed in a highly concentrated (110 mM), isotonic solution of Gd-DTPA, which causes the break of a relaxation recovery into a double exponential curve. Analysis by a two-compartment exchange model yields a value of 50-70 S-1 for the water-exchange rate through cell membranes in intact muscle tissue

  20. Rheological characteristics and stability of highly concentrated suspension of Kuznetsk coal

    Energy Technology Data Exchange (ETDEWEB)

    Borzov, A.I.; Kolesnikova, S.M.; Sikilinda, N.G.; Lazareva, L.V.; Vorontsova, L.O.; Kuznetsov, V.M.

    1987-03-01

    Studies properties of highly concentrated suspensions of various grades of coal from the Inskaya mine (Kuznetsk region). Investigates possibility of utilization of coal-alkali reagent obtained from oxidized Kansk-Achinsk brown coal in the capacity of plasticizing additive, and rheological properties and stability of suspensions related to physical-chemical composition, size and ash content of coal. States that: application of coal-alkali in combination with sodium carbonate or caustic soda makes it possible to obtain stable, highly concentrated (62-65% dry mass) suspensions of coal with ash content varying from 3 to 40%; maximum reduction in rheological properties (2-4 times) was observed during use of coal-alkali reagent (0.2-0.5%) in suspensions with pH equal to 11.5-12.5. 3 refs.

  1. High concentrations of anthocyanins in genuine cherry-juice of old local Austrian Prunus avium varieties.

    Science.gov (United States)

    Schüller, Elisabeth; Halbwirth, Heidi; Mikulic-Petkovsek, Maja; Slatnar, Ana; Veberic, Robert; Forneck, Astrid; Stich, Karl; Spornberger, Andreas

    2015-04-15

    Antioxidant activity and polyphenols were quantified in vapour-extracted juice of nine Austrian, partially endemic varieties of sweet cherry (Prunus avium): cv. 'Spätbraune von Purbach', cv. 'Early Rivers', cv. 'Joiser Einsiedekirsche', cv. 'Große Schwarze Knorpelkirsche' and four unidentified local varieties. Additionally the effect of storage was evaluated for six of the varieties. A variety showing the highest antioxidant capacity (9.64 ?mol Trolox equivalents per mL), total polyphenols (2747 mg/L) and total cyanidins (1085 mg/L) was suitable for mechanical harvest and its juice did not show any losses of antioxidant capacity and total anthocyanin concentration during storage. The juice of cv. 'Große Schwarze Knorpelkirsche' had also high concentrations of total anthocyanins (873 mg/L), but showed substantial losses through storage. The local Austrian sweet cherry varieties from the Pannonian climate zone are particularly suitable for the production of processed products like cherry juice with high content of anthocyanins and polyphenols. PMID:25466109

  2. Maximum entropy estimation of a Benzene contaminated plume using ecotoxicological assays

    International Nuclear Information System (INIS)

    Ecotoxicological bioassays, e.g. based on Danio rerio teratogenicity (DarT) or the acute luminescence inhibition with Vibrio fischeri, could potentially lead to significant benefits for detecting on site contaminations on qualitative or semi-quantitative bases. The aim was to use the observed effects of two ecotoxicological assays for estimating the extent of a Benzene groundwater contamination plume. We used a Maximum Entropy (MaxEnt) method to rebuild a bivariate probability table that links the observed toxicity from the bioassays with Benzene concentrations. Compared with direct mapping of the contamination plume as obtained from groundwater samples, the MaxEnt concentration map exhibits on average slightly higher concentrations though the global pattern is close to it. This suggest MaxEnt is a valuable method to build a relationship between quantitative data, e.g. contaminant concentrations, and more qualitative or indirect measurements, in a spatial mapping framework, which is especially useful when clear quantitative relation is not at hand. - Highlights: ? Ecotoxicological shows significant benefits for detecting on site contaminations. ? MaxEnt to rebuild qualitative link on concentration and ecotoxicological assays. ? MaxEnt shows similar pattern when compared with concentrations map of groundwater. ? MaxEnt is a valuable method especially when quantitative relation is not at hand. - A Maximum Entropy method to rebuild qualitative relationships betweld qualitative relationships between Benzene groundwater concentrations and their ecotoxicological effect.

  3. Prediction of high concentrations and concentration distribution of a continuous point source release in a semi-idealized urban canopy using CFD-RANS modeling

    Science.gov (United States)

    Efthimiou, George C.; Berbekar, Eva; Harms, Frank; Bartzis, John G.; Leitl, Bernd

    2015-01-01

    One of the key issues in recent research on dispersion in complex urban areas is the ability predicting high concentrations and concentration distribution of a pollutant released continuously from a point source. The present work addresses the question whether the CFD-RANS methodology can provide valid predictions of concentration peaks and distributions. A probabilistic and a deterministic approach are incorporated in the CFD-RANS code ADREA. Innovative algebraic equations for the calculation of the concentration time scales as a function of the hydrodynamic and pollutant travel times are used. The capabilities of the new methodology are validated against wind tunnel experimental data under well described boundary conditions and representative concentration measurements. The comparisons of model and wind tunnel gave fairly good results.

  4. Effects of high glucose concentrations on the endothelial function of the renal microcirculation of rabbits

    OpenAIRE

    Affonso Filipe de Souza; Cailleaux Solange; Pinto Leonardo Felipe Corrêa; Gomes Marília de Brito; Tibiriçá Eduardo

    2003-01-01

    OBJECTIVE: To assess the acute effects of high glucose concentrations on vascular reactivity in the isolated non diabetic rabbit kidney. METHODS: Rabbits were anaesthetized for isolation of the kidneys. Renal arteries and veins were cannulated for perfusion with Krebs-Henselleit solution and measurement of perfusion pressure. After 3 hours of perfusion with glucose 5,5 mM (control ) and 15 mM, the circulation was submitted to sub maximal precontraction (80% of maximal response) trough continu...

  5. Single-concentration broth microdilution test for detection of high-level aminoglycoside resistance in enterococci.

    OpenAIRE

    Zervos, M. J.; Patterson, J. E.; Edberg, S.; Pierson, C.; Kauffman, C. A.; Mikesell, T. S.; Schaberg, D. R.

    1987-01-01

    Growth in a single broth microdilution well containing gentamicin at a concentration of 500 micrograms/ml predicted high-level resistance to gentamicin (MIC, greater than or equal to 2,000 micrograms/ml) in 505 of 508 clinical isolates of enterococci. Failure to achieve synergistic killing with the combination of penicillin and an aminoglycoside was demonstrated with 100% specificity in 20 strains which showed resistance to 500 micrograms of gentamicin per ml. We recommend this procedure be a...

  6. Aggregation of Normal and Sickle Hemoglobin in High Concentration Phosphate Buffer

    OpenAIRE

    Chen, Kejing; Ballas, Samir K.; Hantgan, Roy R.; Kim-shapiro, Daniel B.

    2004-01-01

    Sickle cell disease is caused by a mutant form of hemoglobin, hemoglobin S, that polymerizes under hypoxic conditions. The extent and mechanism of polymerization are thus the subject of many studies of the pathophysiology of the disease and potential treatment strategies. To facilitate such studies, a model system using high concentration phosphate buffer (1.5 M–1.8 M) has been developed. To properly interpret results from studies using this model it is important to understand the similarit...

  7. Prediction of Stress Concentration effect under Thermal and Dynamic loads on a High Pressure Turbine Rotor

    OpenAIRE

    Nagendra Babu, R.; Ramana, Dr K. V.; Mallikarjuna Rao, Dr K.

    2010-01-01

    Geometric discontinuities cause a large variation of stress and produce a significant increase in stress. The high stress due to the variation of geometry is called as ‘stress concentration’. This will increase when the loads are further applied. There are many investigators who have studied the stress distribution around the notches, grooves, and other irregularities of various machine components. This paper analyses the effects of thermal and fatigue load on a steam turbine rotor under ...

  8. Radon daughters in the occupants of a house with an unusually high concentration of airborne radon

    International Nuclear Information System (INIS)

    The residents of a house which has high radon concentrations contain easily measurable levels of radon daughters (typically approx. 400 Bq of 214Bi). The results of the measurements are reported and some calculations of absorbed dose to lung, and of the growth of 210Pb in vivo are presented. The relevance of the findings to the problem of assay of plutonium in lung is also discussed

  9. DIFFUSION COEFFICIENTS IN POLYMER-SOLVENT SYSTEMS FOR HIGHLY CONCENTRATED POLYMER SOLUTIONS

    OpenAIRE

    Reis, R. A.; Vladimir Oliveira, J.; Nobrega, R.

    2001-01-01

    The Vrentas/Duda proposal for the diffusion of polymer-solvent systems, which is based on the free-volume theory, was employed in correlating and predicting mutual diffusion coefficients in highly concentrated polymer solutions. It has been observed that the predictive version of the model is capable of qualitatively representing the experimental data, while the use of an adjustable parameter greatly improves the performance of the model. The systems studied were poly(vinyl) acetate-toluene a...

  10. MEASURING NICOTINE INTAKE AMONG HIGHLY DEPENDENT ADOLESCENT SMOKERS: COMPARABILITY OF SALIVA AND PLASMA COTININE CONCENTRATIONS

    OpenAIRE

    Parzynski, Craig S.; Jaszyna-gasior, Maria; Franken, Frederick H.; Moolchan, Eric T.

    2007-01-01

    Cotinine is the most common biomarker used to assess nicotine exposure and abstinence. It can be measured in various matrices including saliva, plasma, and urine. Previous research with adults has shown high correlations between saliva and plasma cotinine concentrations. However, research has not examined this relationship in adolescents. Additionally, variability in saliva flow and metabolism across gender, ethnicity, and age may impact the relationship between saliva and plasma cotinine con...

  11. FBAR Syndapin 1 recognizes and stabilizes highly curved tubular membranes in a concentration dependent manner

    OpenAIRE

    Pradeep Ramesh; Baroji, Younes F.; Reihani, S. Nader S.; Dimitrios Stamou; Oddershede, Lene B.; Poul Martin Bendix

    2013-01-01

    Syndapin 1 FBAR, a member of the Bin-amphiphysin-Rvs (BAR) domain protein family, is known to induce membrane curvature and is an essential component in biological processes like endocytosis and formation and growth of neurites. We quantify the curvature sensing of FBAR on reconstituted porcine brain lipid vesicles and show that it senses membrane curvature at low density whereas it induces and reinforces tube stiffness at higher density. FBAR strongly up-concentrates on the high curvature tu...

  12. Interactions between Adsorbed Hydrogenated Soy Phosphatidylcholine (HSPC) Vesicles at Physiologically High Pressures and Salt Concentrations

    OpenAIRE

    Goldberg, Ronit; Schroeder, Avi; Barenholz, Yechezkel; Klein, Jacob

    2011-01-01

    Using a surface force balance, we measured normal and shear interactions as a function of surface separation between layers of hydrogenated soy phosphatidylcholine (HSPC) small unilamellar vesicles (SUVs) adsorbed from dispersion at physiologically high salt concentrations (0.15 M NaNO3). Cryo-scanning electron microscopy shows that each surface is coated by a close-packed HSPC-SUV layer with an overlayer of liposomes on top. A clear attractive interaction between the liposome layers is seen...

  13. Status of Ultra-High Concentrator Multijunction Solar Cell Development at IES-UPM.

    OpenAIRE

    Rey-stolle Prado, Ignacio; Algora Del Valle, Carlos; Barrigo?n Montan?e?s, Enrique; Garcia Tabares Valdivieso, Elisa; Garci?a Vara, Iva?n; Espinet Gonza?lez, Pilar

    2010-01-01

    After the successful implementation of a record performing dual-junction solar cell at ultra high concentration, in this paper we present the optimization of key aspects in the transition to a triple-junction device, namely the hetero nucleation of III-V structures onto germanium substrates. This optimization is based on in-situ RAS measurements during the MOVPE growth of the triple-junction solar cell structure and subsequent AFM analysis. The correlation between RAS and AFM allows detecting...

  14. Evaluation of Culture Methods To Identify Bovine Feces with High Concentrations of Escherichia coli O157?

    OpenAIRE

    Fox, J. Trent; Renter, David G.; Sanderson, Michael W.; Thomson, Daniel U.; Lechtenberg, Kelly F.; Nagaraja, T. G.

    2007-01-01

    Our objective was to evaluate methods for identifying cattle with high concentrations of Escherichia coli O157 in their feces. In two experiments, feces were collected from cattle orally inoculated with nalidixic acid (Nal)-resistant E. coli O157, and direct plating of diluted feces on sorbitol MacConkey agar with cefixime and potassium tellurite (CT-SMAC) containing Nal was considered the gold standard (GS) method. In experiment 1, methods evaluated were preenrichment direct streak, immunoma...

  15. Optimizing Concentric Circular Antenna Arrays for High-Altitude Platforms Wireless Sensor Networks

    OpenAIRE

    Yasser Albagory; Omar Said

    2014-01-01

    Wireless Sensor Networks (WSN) has gained interest in many applications and it becomes important to improve its performance. Antennas and communication performance are most important issues of WSN. In this paper, an adaptive concentric circular array (CCA) is proposed to improve the link between the sink and sensor nodes. This technique is applied to the new High – Altitude Platform (HAP) Wireless Sensor Network (WSN). The proposed array technique is applied for two coverage scenarios; a wi...

  16. Advanced high efficiency concentrator cells. Final subcontractor report, 1 October 1988--31 March 1990

    Energy Technology Data Exchange (ETDEWEB)

    Gale, R. [Varian Associates, Inc., Palo Alto, CA (United States). Varian Research Center

    1992-06-01

    This report describes research to develop the technology needed to demonstrate a monolithic, multijunction, two-terminal, concentrator solar cell with a terrestrial power conversion efficiency greater than 35%. Under three previous subcontracts, Varian developed many of the aspects of a technology needed to fabricate very high efficiency concentrator cells. The current project was aimed at exploiting the new understanding of high efficiency solar cells. Key results covered in this report are as follows. (1) A 1.93-eV AlGaAs/1.42-eV GaAs metal-interconnected cascade cell was manufactured with a one-sun efficiency at 27.6% at air mass 1.5 (AM1.5) global. (2) A 1.0eV InGaAs cell was fabricated on the ``reverse`` side of a low-doped GaAs substrate with a one-sun efficiency of 2.5% AM1.5 diffuse and a short-circuit current of 14.4 mA/cm{sup 2}. (3) Small-scale manufacturing of GaAs p/n concentrator cells was attempted and obtained an excellent yield of high-efficiency cells. (4) Grown-in tunnel junction cell interconnects that are transparent and thermally stable using C and Si dopants were developed. 10 refs.

  17. Numerical simulations of high-concentration-gradient dispersion in porous media

    Science.gov (United States)

    Landman, A. J.; Schotting, R. J.; Johannsen, K.

    2003-04-01

    We present the results of a detailed numerical study of stable brine displacements in a heterogeneous porous medium. An upward flow of brine (a high salt concentration solution) displaces fresh water in a vertical heterogeneous column. Experimental findings have shown that when high gradients in concentration exist, the commonly used linear Fickian-type law for dispersion does not hold. In a stable configuration, the observed solute dispersion decreases with increasing density difference between the fluids. This effect is believed to be caused by stabilizing gravity forces. We presume that the standard equations for transport in porous media are valid at the local scale. At this scale, heterogeneities in permeability give rise to irregularities in the initially horizontal brine front. The non-vertical density gradients that arise are a driving force for gravity flow. We accurately simulate these small scale phenomena using d3f, a well-tested and highly advanced parallel computer code for density dependent flow in porous media. The computed breakthrough curves for a horizontally averaged concentration indeed show a decrease in the observed dispersivity with increasing density difference. This is in accordance with experimental and theoretical findings. We further analyze the numerical results using a non-linear dispersion theory introduced by Hassanizadeh and Leijnse in 1995. We investigate the behaviour of the new dispersion parameter involved, in relation to flow velocity, density difference and medium properties.

  18. Simulation of high concentration of iron in dense shelf water in the Okhotsk Sea

    Science.gov (United States)

    Uchimoto, Keisuke; Nakamura, Tomohiro; Nishioka, Jun; Mitsudera, Humio; Misumi, Kazuhiro; Tsumune, Daisuke; Wakatsuchi, Masaaki

    2014-08-01

    An ocean general circulation model coupled with a simple biogeochemical model was developed to simulate iron circulation in and around the Sea of Okhotsk. The model has two external sources of iron: dust iron at the sea surface and sedimentary iron at the seabed shallower than 300 m. The model represented characteristic features reasonably well, such as high iron concentration in the dense shelf water (DSW) and its mixing, which extends southward in the intermediate layer from the northwestern shelf along Sakhalin Island and finally flows into the Pacific. Sensitivity experiments for the solubility of dust iron in seawater suggest that a solubility of 1% is appropriate in our simulation. Higher solubilities (5% and 10%) result in too low phosphate in the northwestern North Pacific in summer as well as too high iron concentrations at the sea surface, compared with observations. Besides, these experiments show that dust iron hardly contributes to the high iron concentration in the intermediate layer. To investigate locations from which the iron in the intermediate layer originates, the fate of sedimentary iron input from four regions in the Okhotsk Sea was examined. Results suggest that the western and central parts of the northern shelf are important.

  19. Single-molecule imaging at high fluorophore concentrations by local activation of dye.

    Science.gov (United States)

    Geertsema, Hylkje J; Schulte, Aartje C; Spenkelink, Lisanne M; McGrath, William J; Morrone, Seamus R; Sohn, Jungsan; Mangel, Walter F; Robinson, Andrew; van Oijen, Antoine M

    2015-02-17

    Single-molecule fluorescence microscopy is a powerful tool for observing biomolecular interactions with high spatial and temporal resolution. Detecting fluorescent signals from individual labeled proteins above high levels of background fluorescence remains challenging, however. For this reason, the concentrations of labeled proteins in in vitro assays are often kept low compared to their in vivo concentrations. Here, we present a new fluorescence imaging technique by which single fluorescent molecules can be observed in real time at high, physiologically relevant concentrations. The technique requires a protein and its macromolecular substrate to be labeled each with a different fluorophore. Making use of short-distance energy-transfer mechanisms, only the fluorescence from those proteins that bind to their substrate is activated. This approach is demonstrated by labeling a DNA substrate with an intercalating stain, exciting the stain, and using energy transfer from the stain to activate the fluorescence of only those labeled DNA-binding proteins bound to the DNA. Such an experimental design allowed us to observe the sequence-independent interaction of Cy5-labeled interferon-inducible protein 16 with DNA and the sliding via one-dimensional diffusion of Cy5-labeled adenovirus protease on DNA in the presence of a background of hundreds of nanomolar Cy5 fluorophore. PMID:25692599

  20. High concentrations of heavy metals in PM from ceramic factories of Southern Spain

    Science.gov (United States)

    Sánchez de la Campa, Ana M.; de la Rosa, Jesús D.; González-Castanedo, Yolanda; Fernández-Camacho, Rocío; Alastuey, Andrés; Querol, Xavier; Pio, Casimiro

    2010-06-01

    In this study, physicochemical characterization of Atmospheric Particulate Matter (PM) was performed in an urban-industrial site background (Bailén, Southern Spain), highly influenced by the impact of emission plumes from ceramic factories. This area is considered one of the towns with the highest PM 10 levels and average SO 2 concentration in Spain. A three stages methodology was used: 1) real-time measurements of levels of PM 10 and gaseous pollutants, and sampling of PM; 2) chemical characterization using ICP-MS, ICP-OES, CI and TOT, and source apportionment analysis (receptor modelling) of PM; and 3) chemical characterization of emission plumes derived from representative factories. High ambient air concentrations were found for most major components and trace elements compared with other industrialized towns in Spain. V and Ni are considered fingerprints of PM derived from the emissions of brick factories in this area, and were shown to be of particular interest. This highlights the high V and Ni concentrations in PM 10 (122 ngV/m 3 and 23.4 ngNi/m 3), with Ni exceeding the 2013 annual target value for the European Directive 2004/107/EC (20 ng/m 3). The methodology of this work can be used by Government departments responsible for Environment and Epidemiology in planning control strategies for improving air quality.

  1. Implications of Industrial Processing Strategy on Cellulosic Ethanol Production at High Solids Concentrations

    DEFF Research Database (Denmark)

    Cannella, David

    2013-01-01

    The production of cellulosic ethanol is a biochemical process of not edible biomasses which contain the cellulose. The process involves the use of enzymes to hydrolyze the cellulose in fermentable sugars to finally produce ethanol via fermentative microorganisms (i.e. yeasts). These biomasses are the leftover of agricultural productions (straws), not edible crops (giant reed) or wood, thus the ethanol so produced is also called second generation (or 2G ethanol), which differs from the first generation produced from starch (sugar beets mostly). In the industrial production of cellulosic ethanol high solids strategy resulted critical for its cost effectiveness: high concentration of initial biomass it will lead to high concentration of the final product (ethanol), thus more convenient to isolate. This thesis investigate the implementation of a high solids loading concept into cellulosic ethanol technology using new enzymatic cellulolytic cocktails, and how a high solids setup may affect the overall process design. The thesis focuses on two main biomasses: an agricultural feedstock such as wheat straw and a woody feedstock such as Norwegian spruce. The best performing strategy for cellulosic ethanol fermentation at high solids loading, in terms of maximized final conversion yield, is the overall aim of the work conducted. This thesis also revisits the knowledge already acquired in light of new enzymatic activities recently discovered i.e. lytic polysaccharides mono oxygenases (LPMOs), and how these ffects cellulosic ethanol processing at high solids conditions. Moreover for the first time in literature the activity of LPMOs on real lignocellulosic substrate and during cellulosic ethanol production is characterized. Hence describing the enzymatic scale dynamics when resembling in planta conditions, i.e. environments resembling the natural conditions of lignocellulose as substrate a d high dry matter. This can in turn lead to a better understanding of what could happen and be optimized while designing a reactor fora high solids environment

  2. BENZENE VAPOR DEPLETION IN THE PRESENCE OF PLANTS

    Science.gov (United States)

    Three plant species, Eichhornia crassipes in a nutrient hydroponic culture Beta vulgaris saccharifera, and Beta vulgaris cicla in soil and in water cultures, were found to deplete benzene from the air. Following benzene depletion, plant tissues were extracted and no benzene was d...

  3. PERINATAL IMMUNOTOXICITY OF BENZENE TOWARD MOUSE B CELL DEVELOPMENT

    Science.gov (United States)

    Benzene is widely used by chemical industries and exposure to benzene has been shown experimentally to be immunotoxic in adult animals. The present study addressed whether exposure of fetuses in utero to benzene compromises the development of fetal B lymphopoiesis and whether B l...

  4. The Effects of High Concentrations of Vitamin C on Cancer Cells

    OpenAIRE

    Seyeon Park

    2013-01-01

    The effect of high doses of vitamin C for the treatment of cancer has been controversial. Our previous studies, and studies by others, have reported that vitamin C at concentrations of 0.25–1.0 mM induced a dose- and time-dependent inhibition of proliferation in acute myeloid leukemia (AML) cell lines and in leukemic cells from peripheral blood specimens obtained from patients with AML. Treatment of cells with high doses of vitamin C resulted in an immediate increase in intracellular total ...

  5. Ge doped GaN with controllable high carrier concentration for plasmonic applications

    International Nuclear Information System (INIS)

    Controllable Ge doping in GaN is demonstrated for carrier concentrations of up to 2.4?×?1020 cm?3. Low temperature luminescence spectra from the highly doped samples reveal band gap renormalization and band filling (Burstein-Moss shift) in addition to a sharp transition. Infrared ellipsometry spectra demonstrate the existence of electron plasma with an energy around 3500?cm?1 and a surface plasma with an energy around 2000?cm?1. These findings open possibilities for the application of highly doped GaN for plasmonic devices

  6. A SIMPLE WAY OF ACHIEVING A HIGH CELL CONCENTRATION IN RECOMBINANT Escherichia coli CULTIVATION

    Scientific Electronic Library Online (English)

    A.K., Gombert; B.V., Kilikian.

    1997-06-01

    Full Text Available SciELO Brazil | Language: English Abstract in english Abstract - A cultivation strategy based on some previous knowledge of the metabolism of Escherichia coli BL21 (DE3) pLysS containing the troponin C gene cloned into plasmid pET was developed and applied through the use of simple fermentation equipment and a feed-forward control strategy in order to [...] achieve a high cell concentration ¾ 92 g l-1 dry cell weight ¾ and a high cell productivity ¾ 3.7 g l-1 h-1.

  7. Photocatalytic Degradation of Linear Alkyl Benzene Solfunate from Aqueous Solution by TiO2 Nanoparticles

    Directory of Open Access Journals (Sweden)

    K. Naddafi

    2011-10-01

    Full Text Available The possibility of linear alkyl benzene solfunate (LAS photocatalytic degradation through application of TiO2 nanoparticles was investigated. 10(mg/L of LAS has been affected by either UV or TiO2 and simultaneous use of both of them in separated experiments. Moreover, the effect of initial concentrations of LAS and TiO2, pH, present various anions and different UV power was studied to determine the optimal operating conditions for LAS degradation in water. The amount of mineralization of LAS was reported by measuring the primary and final COD of the solution that was irradiated under optimized conditions. Maximum degradation was obtained at acidic pH, 50 mg/L of TiO2 and 30 minute irradiation time. It was also shown that 99.5% of LAS was degraded in optimal conditions. Kinetic analysis indicated that photo catalytic degradation rates of LAS can be approximated by pseudo-first order model. Measuring the initial and final COD of illuminated solution under optimized conditions, indicated that almost complete mineralization of LAS was occurred. Based on the results, UV/TiO2 process may be effectively applied in LAS removal in low concentrations but this process is not economically efficient in high concentrations.

  8. Rheology of corn stover slurries at high solids concentrations--effects of saccharification and particle size.

    Science.gov (United States)

    Viamajala, Sridhar; McMillan, James D; Schell, Daniel J; Elander, Richard T

    2009-01-01

    The rheological characteristics of untreated and dilute acid pretreated corn stover (CS) slurries at high solids concentrations were studied under continuous shear using plate-plate type measurements. Slurry rheological behavior was examined as a function of insoluble solids concentration (10-40%), extent of pretreatment (0-75% removal of xylan) and particle size (-20 and -80 mesh). Results show that CS slurries exhibit shear-thinning behavior describable using a Casson model. Further, results demonstrate that the apparent viscosity and yield stress increase with increasing solids concentration (which corresponds to a decrease in free water). Dilute acid pretreatment leads to lower viscosity and yield stresses at equivalent solids concentrations, as does smaller particle size. Taken together, these findings are consistent with the hypothesis that the availability of free water in the slurry plays a significant role in determining its rheological behavior. In particular, as the free water content of the slurry decreases, e.g., with increasing solids concentration, the greater interaction among particles likely increases the apparent viscosity and yield stress properties of the slurry. The results also suggest that the availability of free water, and thereby slurry rheological properties, depend on the chemical composition of the corn stover as well as its physical characteristics such as particle size and porosity. Hydrophilic polymers within the cell wall, such as xylan or pectin, or larger pores within bigger particles, facilitate sequestration of water in the solid phase resulting in decreased availability of free water. Thus, dilute acid pretreated slurries, which contain smaller size particles having significantly lower xylan content than slurries of untreated milled stover, exhibit much lower viscosities and yield stresses than untreated slurries containing large particles at similar solid concentrations. PMID:18760597

  9. Hydrogen-terminated silicon nanowire photocatalysis: Benzene oxidation and methyl red decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Lian, Suoyuan [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); School of Chemical Engineering and Materials, Dalian Polytechnic University, Dalian 116034 (China); Tsang, Chi Him A. [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Centre of Super Diamond and Advanced Films, City University of Hong Kong, Hong Kong (China); Kang, Zhenhui, E-mail: zhkang@suda.edu.cn [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Liu, Yang, E-mail: yangl@suda.edu.cn [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Wong, Ningbew [Centre of Super Diamond and Advanced Films, City University of Hong Kong, Hong Kong (China); Lee, Shuit-Tong [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Centre of Super Diamond and Advanced Films, City University of Hong Kong, Hong Kong (China)

    2011-12-15

    Graphical abstract: H-SiNWs can catalyze hydroxylation of benzene and degradation of methyl red under visible light irradiation. Highlights: Black-Right-Pointing-Pointer Hydrogen-terminated silicon nanowires were active photocatalyst in the hydroxylation of benzene under light. Black-Right-Pointing-Pointer Hydrogen-terminated silicon nanowires were also effective in the decomposition of methyl red dye. Black-Right-Pointing-Pointer The Si/SiO{sub x} core-shell structure is the main reason of the obtained high selectivity during the hydroxylation. -- Abstract: Hydrogen-terminated silicon nanowires (H-SiNWs) were used as heterogeneous photocatalysts for the hydroxylation of benzene and for the decomposition of methyl red under visible light irradiation. The above reactions were monitored by GC-MS and UV-Vis spectrophotometry, respectively, which shows 100% selectivity for the transformation of benzene to phenol. A complete decomposition of a 2 Multiplication-Sign 10{sup -4} M methyl red solution was achieved within 30 min. The high selectivity for the hydroxylation of benzene and the photodecomposition demonstrate the catalytic activity of ultrafine H-SiNWs during nanocatalysis.

  10. Hydrogen-terminated silicon nanowire photocatalysis: Benzene oxidation and methyl red decomposition

    International Nuclear Information System (INIS)

    Graphical abstract: H-SiNWs can catalyze hydroxylation of benzene and degradation of methyl red under visible light irradiation. Highlights: ? Hydrogen-terminated silicon nanowires were active photocatalyst in the hydroxylation of benzene under light. ? Hydrogen-terminated silicon nanowires were also effective in the decomposition of methyl red dye. ? The Si/SiOx core-shell structure is the main reason of the obtained high selectivity during the hydroxylation. -- Abstract: Hydrogen-terminated silicon nanowires (H-SiNWs) were used as heterogeneous photocatalysts for the hydroxylation of benzene and for the decomposition of methyl red under visible light irradiation. The above reactions were monitored by GC–MS and UV–Vis spectrophotometry, respectively, which shows 100% selectivity for the transformation of benzene to phenol. A complete decomposition of a 2 × 10?4 M methyl red solution was achieved within 30 min. The high selectivity for the hydroxylation of benzene and the photodecomposition demonstrate the catalytic activity of ultrafine H-SiNWs during nanocatalysis.

  11. Sub-Doppler electronic spectra of the benzene–(He)n complexes

    International Nuclear Information System (INIS)

    Highlights: ? Fully rotationally resolved excitation spectra of benzene–He1,2 were recorded. ? Distance between benzene and He is longer than those in the Ne and Ar complexes. ? Electronic excitation causes the increase of the intermolecular distance. ? The experimental results are compared with a recent theoretical calculation. - Abstract: Excitation spectra of the benzene–(He)n (n = 1 and 2) van der Waals complexes in the vicinity of the S1 ? S0601 vibronic transition of the monomer were recorded by utilizing mass-selectivetwo-color resonance-enhanced two-photon ionization. Pulsed expansion with the stagnation pressure of 80 bar was incorporated for efficient formation of the most weakly bound aromatic complexes and extensive adiabatic cooling with the rotational temperature of 1 ? S0 excitation. The observed transition frequencies were fitted to the conventional symmetric-top Hamiltonian with a standard deviation of 0 state of the complex with n = 1. The distance is even larger than those of the analogous systems, i.e., benzene–Ne and –Ar, and this apparent anomaly is discussed with the recent theoretical results based on high-level quantum mechanical calculation coupled with the numerical solution of the 3D eigenvalue problem. The electronic excitation induces the increase by 0.063 ± 0.012 Å, as opposed to the contraction of other benzene–rare gas complexes. The distance and the change for n = 2 are almost the same (3.596 ± 0.006 Å and 0.067 ± 0.009 Å) as those for n = 1. We also recorded the excitation spectrum of the n = 1 complex with the mono 13C-substituted benzene molecule. The asymmetric substitution lifts the degeneracy of the S1 61 state in the benzene molecule, and two vibronic bands located nearby to each other were observed for the complex

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

    Directory of Open Access Journals (Sweden)

    Zhengjun Zhang

    2011-12-01

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

  13. Ab initio investigation of intermolecular interactions in solid benzene

    CERN Document Server

    Bludsky, O; Soldan, P; 10.1103/PhysRevB.77.092103

    2009-01-01

    A computational strategy for the evaluation of the crystal lattice constants and cohesive energy of the weakly bound molecular solids is proposed. The strategy is based on the high level ab initio coupled-cluster determination of the pairwise additive contribution to the interaction energy. The zero-point-energy correction and non-additive contributions to the interaction energy are treated using density functional methods. The experimental crystal lattice constants of the solid benzene are reproduced, and the value of 480 meV/molecule is calculated for its cohesive energy.

  14. 29 CFR 1915.1028 - Benzene.

    Science.gov (United States)

    2010-07-01

    29 ? Labor ? 7 ? 2010-07-01 ? 2010-07-01 ? false ? Benzene. ? 1915.1028 ? Section 1915.1028 ? Labor ? Regulations Relating to Labor (Continued) ? OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) ? OCCUPATIONAL SAFETY AND HEALTH STANDARDS FOR SHIPYARD EMPLOYMENT ?...

  15. Radiation-induced chlorination of benzene

    International Nuclear Information System (INIS)

    Radiation-induced process of the benzene chlorination to achieving the maximum yield of ?-hexachlorocyclohexane (?-HCH) was investigated. The influence of temperature, flow rate of chlorine and dose rate of ?-radiation was appointed. The addition of such halogenohydrocarbons as dichloromethane and tetrachloroethane, to reacting system increased ?-HCH content in the products mixture. (author)

  16. Benzene-1,3,5-tricarbonyl trichloride

    OpenAIRE

    Xin Fan; Yanrong Wang; Chengzhi Jin; Longfei Jin

    2012-01-01

    In the title molecule, C9H3Cl3O3, there are three short interactions involving the benzene H atoms and the chloro­formyl Cl atoms. In the crystal, mol­ecules stack along the a axis with no significant non-bonded inter­actions.

  17. 46 CFR 151.50-60 - Benzene.

    Science.gov (United States)

    2010-10-01

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

  18. Benzene nitration: validation of heterogeneous reaction models

    OpenAIRE

    Quadros, Paulo A.; Oliveira, Nuno M. C.; Baptista, Cristina M. S. G.

    2004-01-01

    The film and the Danckwerts penetration models were used to model the heterogeneous liquid-liquid reaction of benzene nitration. Analytical solutions were developed for both models considering a pseudo-first order reaction. Models were confronted with experimental results showing good predictions in the intermediate reaction regime (0.3

  19. 29 CFR 1926.1128 - Benzene.

    Science.gov (United States)

    2010-07-01

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

  20. 46 CFR 153.1060 - Benzene.

    Science.gov (United States)

    2010-10-01

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

  1. Systems biology of human benzene exposure.

    OpenAIRE

    Zhang, L.; Mchale, C. M.; Rothman, N.; Li, G.; Ji, Z.; Vermeulen, R.; Hubbard, A. E.; Ren, X.; Shen, M.; Rappaport, S. M.; North, M.; Skibola, C. F.; Yin, S.; Vulpe, C.; Chanock, S. J.

    2010-01-01

    Toxicogenomic studies, including genome-wide analyses of susceptibility genes (genomics), gene expression (transcriptomics), protein expression (proteomics), and epigenetic modifications (epigenomics), of human populations exposed to benzene are crucial to understanding gene-environment interactions, providing the ability to develop biomarkers of exposure, early effect and susceptibility. Comprehensive analysis of these toxicogenomic and epigenomic profiles by bioinformatics in the context of...

  2. 27 CFR 21.97 - Benzene.

    Science.gov (United States)

    2010-04-01

    (For applicable ASTM method, see 1980 Annual Book of ASTM Standards, Part 29, page 573, Standard No. D 836-77; for incorporation by reference, see § 21.6(b).) When 100 ml of benzene are distilled by this method, not more than 1 ml should distill below 77 °C., and not less than 95 ml below 85...

  3. Formation of Benzene in the Interstellar Medium

    Science.gov (United States)

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

    2010-01-01

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

  4. Recommended sublimation pressure and enthalpy of benzene.

    Czech Academy of Sciences Publication Activity Database

    R?ži?ka, K.; Fulem, Michal; ?ervinka, C.

    2014-01-01

    Ro?. 68, Jan (2014), s. 40-47. ISSN 0021-9614 Institutional support: RVO:68378271 Keywords : benzene * vapor pressure * heat capacity * ideal-gas thermodynamic properties * sublimation enthalpy * recommended vapor pressure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.423, year: 2013

  5. Thermal Shock Behavior of Single Crystal Oxide Refractive Concentrators for High Temperatures Solar Thermal Propulsion

    Science.gov (United States)

    Zhu, Dongming; Choi, Sung R.; Jacobson, Nathan S.; Miller, Robert A.

    1999-01-01

    Single crystal oxides such as yttria-stabilized zirconia (Y2O3-ZrO2), yttrium-aluminum-garnet (Y3Al5O12, or YAG), magnesium oxide (MgO) and sapphire (Al2O3) have been considered as refractive secondary concentrator materials for high temperature solar propulsion applications. However, thermal mechanical reliability of the oxide components in severe thermal environments during space mission sun/shade transitions is of great concern. In this paper, critical mechanical properties of these oxide crystals are determined by the indentation technique. Thermal shock resistance of the oxides is evaluated using a high power CO, laser under high temperature-high thermal gradients. Thermal stress fracture behavior and failure mechanisms of these oxide materials are investigated under various temperature and heating conditions.

  6. Density functional theory studies of Nb–benzene and Nb–borazine sandwich clusters and molecular wires

    International Nuclear Information System (INIS)

    We systematically explored the stabilities, bonding characteristics, electronic and magnetic properties of sandwich-structured Nbn(benzene)n+1 and Nbn(borazine)n+1 clusters (n = 1?4) and molecular wires (n = ?) based on density functional theory. The calculated results show that the lowest energy Nb2(benzene)3 and Nb3(benzene)4 clusters are antiferromagnets (AFMs), while Nb4(benzene)5 is a ferromagnet (FM). An AFM-to-FM transition occurs at n = 4 in the finite Nbn(benzene)n+1 system. For Nbn(borazine)n+1, all the clusters investigated here are ferromagnetically stable. Furthermore, the ground states of infinite [Nb(benzene)]? and [Nb(borazine)]? molecular wires exhibit different electronic structures. The former is a direct-gap ferromagnetic semiconductor, while the latter is a ferromagnetic half-metal. High stabilities and excellent electronic and magnetic properties of [Nb(benzene)]? and [Nb(borazine)]? may be exploited for applications in future electronics and spintronics. (paper)

  7. Anaerobic benzene degradation under denitrifying conditions: Peptococcaceae was identified as dominant benzene degrader by Stable Isotope Probing (SIP)

    OpenAIRE

    Zaan, B. M.; Talarico Saia, F.; Plugge, C. M.; Vos, W. M.; Smidt, H.; Stams, A. J. M.; Langenhoff, A. A. M.; Gerritse, J.

    2012-01-01

    An anaerobic microbial community was enriched in a chemostat that was operated for more than 8 years with benzene and nitrate as electron acceptor. The coexistence of multiple species in the chemostat and the presence of a biofilm, led to the hypothesis that benzene-degrading species coexist in a syntrophic interaction, and that benzene can be degraded in syntrophy by consortia with various electron acceptors in the same culture. The benzene-degrading microorganisms were identified by DNA-sta...

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

    OpenAIRE

    Zhengjun Zhang; Yu Huang; Zhengcao Li; Qin Zhou; Xian Zhang

    2011-01-01

    Detection of persistent pollutants such as polychlorinated benzene in environment in trace amounts is challenging, but important. It is more difficult to distinguish homologues and isomers of organic pollutantd when present in trace amounts because of their similar physical and chemical properties. In this work we simulate the Raman spectra of hexachlorobenzene and benzene, and figure out the vibration mode of each main peak. The effect on the Raman spectrum of changing substituents from H to...

  9. Combustion Processes Indoors: a Source of High OH Radical Concentrations Through the Photolysis of Hono

    Science.gov (United States)

    Bartolomei, V.; Gomez Alvarez, E.; Glor, M.; Gligorovski, S.; Temime-Roussel, B.; Quivet, E.; Strekowski, R.; Zetzsch, C.; Held, A. B.; Wortham, H.

    2013-12-01

    Hydroxyl radical (OH) is one of the most important oxidant species in the atmosphere controlling its self-oxidizing capacity. The main sources of OH radicals are photolysis of ozone and photolysis of nitrous acid (HONO), among the others. In the indoor air, the ozonolysis of alkenes has been suggested as the main OH formation pathway. The possibility for OH formation through photolytic pathways in the indoor environment has been, up to now, ignored (Gómez Alvarez et al., 2012). Models and indirect measurements to the present time predicted concentrations of OH radicals in the order of 104 -105 cm-3. Recently, by direct measurements we have detected high OH radical concentrations of 1.8 106 cm-3 in a classroom in Marseille and we demonstrated that its main source is the photolysis of HONO (Gómez Alvarez et al., 2013). The concentrations of HONO are quite high indoors, reaching levels in the order of a few tens of ppbV (Gómez Alvarez et al., 2013). This is mainly due to 1) direct combustion sources and 2) heterogeneous reactions of NO2 on the numerous surfaces present in the indoor environment. HONO levels of 30 ppb were measured in a previous campaign carried out in Bayreuth in July 2012 as direct emissions from the combustion of a candle. The combination between so high concentrations of HONO and higher than expected light transmissions indoors (or indoor artificial lighting) could have a significant impact on the OH concentrations indoors which could feasibly become considerably higher than we measured in our school campaign (Gomez Alvarez et al., 2013). In order to evaluate these upper limits under combustion conditions in the indoor environment, we have carried out a campaign in the LOTASC chamber (Bayreuth, Germany). For this aim, the exhaust fumes from the burning of a commonly used domestic candle have been introduced in the chamber. The chamber was irradiated under well research indoor lighting conditions. A thorough characterization of light intensities and span (wavelength distribution) indoors have been performed, which had been identified as a clear flaw in our knowledge restricting the advancement of indoor air quality models. OH concentration levels have been determined using d9-butanol as tracer, using the OH clock determination procedure by PTR-MS-TOF. The OH radical concentration was investigated using different light intensities representative from indoor conditions, both natural and artificial and also different levels of RH. The PSS model has been performed in order to evaluate the contribution of different sources to the OH radical concentrations indoors under these conditions. The obtained results from the PSS model clearly indicate that the main source of OH radical indoors under combustion conditions is the photolysis of HONO under typical indoor irradiation conditions. REFERENCES Gómez Alvarez E, Wortham H, Strekowski R, Zetzsch C, Gligorovski S (2012) Atmospheric photo-sensitized heterogeneous and multiphase reactions: From outdoors to indoors, Environ. Sci. Technol. 46, 1955-1963. Gómez Alvarez, E.; Amedro, D.; Afif, C. ; Gligorovski, S.; Schoemacker , C.; Fittschen, C. ; Doussin, J. F.; Wortham, H. (2013) Unexpectedly high indoor hydroxyl radical concentrations associated with nitrous acid. Proc. Natl. Acad. Sci. USA Accepted.

  10. Mechanism for covalence bond benzene dimers formation: A DFT and MP2 investigation

    Science.gov (United States)

    Qin, Yu; Huo, Ruiping; Zhang, Xiang

    2014-08-01

    Covalent dimerization mechanisms of benzene were studied by MP2 and three DFT methods with 6-311G(d,p) basis set. All the methods predicted similar meta- and para-cycloaddition mechanisms. MP2 results showed that (1) the activation enthalpies of both the endo- and exo-meta-cycloadditions are about 90 kcal/mol, twice as high as that of para-cycloaddition and (2) further transformation of para-cycloaddition adduct to D2h-(CH)12 and endo-meta-cycloaddition adduct to D3d-(CH)12 need to surmount high enthalpy barriers of 65.02 and 90.78 kcal/mol (relative to two molecules of benzene), respectively. Molecular orbital analysis revealed that meta-cycloaddition of benzene is ground state allowed reaction.

  11. High fetal plasma adenosine concentration: a role for the fetus in preeclampsia?

    LENUS (Irish Health Repository)

    Espinoza, Jimmy

    2012-02-01

    OBJECTIVE: Clinical observations suggest a role for the fetus in the maternal manifestations of preeclampsia, but the possible signaling mechanisms remain unclear. This study compares the fetal plasma concentrations of adenosine from normal pregnancies with those from preeclampsia. STUDY DESIGN: This secondary data analysis included normal pregnancies (n = 27) and patients with preeclampsia (n = 39). Patients with preeclampsia were subclassified into patients with (n = 25) and without (n = 14) abnormal uterine artery Doppler velocimetry (UADV). RESULTS: Fetal plasma concentrations of adenosine were significantly higher in patients with preeclampsia (1.35 +\\/- 0.09 mumol\\/L) than in normal pregnancies (0.52 +\\/- 0.06 mumol\\/L; P < .0001). Fetal plasma concentrations of adenosine in patients with preeclampsia with abnormal UADV (1.78 +\\/- 0.15 mumol\\/L), but not with normal UADV (0.58 +\\/- 0.14 mumol\\/L), were significantly higher than in normal pregnancies (P < .0001). CONCLUSION: Patients with preeclampsia with sonographic evidence of chronic uteroplacental ischemia have high fetal plasma concentrations of adenosine.

  12. Ultra-High-Concentration Photovoltaic-Thermal Systems Based on Microfluidic Chip-Coolers

    Science.gov (United States)

    Müller, M.; Escher, W.; Ghannam, R.; Goicochea, J.; Michel, B.; Ong, C. L.; Paredes, S.

    2011-12-01

    The electrical efficiency of a photovoltaic-thermal system for coolant inlet temperatures ranging from 25 °C to 75 °C and concentrations from 500 to 1500 suns was investigated experimentally and theoretically. In this system absorbed radiation and thermal losses from the electric circuit are collected in a thermal circuit. This allows one to directly drive a thermal desalination process thereby contributing to an improved system efficiency. A triple-junction solar cell was tested in two different configurations. At 1500 suns the electric efficiency of a silicon microchannel cooler package exceeded the efficiency of a reference package with a copper cooler by 2% and it remained fully functional up to concentrations of 4930 suns. We present a general model for concentrated photovoltaic-thermal systems in which the standard efficiency modeling approaches for triple-junction cells are extended by temperature and concentration dependencies. The currents were modeled both following the Shockley-Queisser and a "real" cell model with temperature dependent material parameters, radiative recombination, and high injection conditions.

  13. The ability of fungus Mucor racemosus Fresenius to degrade high concentration of detergent

    Directory of Open Access Journals (Sweden)

    Jakovljevi? Violeta D.

    2014-01-01

    Full Text Available The ability of fungus Mucor racemosus Fresenius to decompose high concentration of commercial detergent (MERIX, Henkel, Serbia was investigated in this study. Fungus was cultivated in liquid growth medium by Czapek with addition of detergent at concentration 0.5% during 16 days. The biochemical changes of pH, redox potential, amount of free and total organic acids, and activity of alkaline phosphatase were evaluated by analysis of fermentation broth. Simultaneously, biodegradation percentage of anionic surfactant of tested detergent was confirmed by MBAS assay. At the same time, the influence of detergent on fungal growth and total dry weight biomass was determined. Detergent at concentration 0.5% influenced on decreasing of pH value and increasing of redox potential as well as increasing of free and total organic acids. Enzyme activity of alkaline phosphatase was reduced by detergent at concentration 0.5%. The fungus was decomposed about 62% of anionic surfactant during 16 day. Due to fungus was produced higher dry weight biomass (53% in relation to control. [Projekat Ministarstva nauke Republike Srbije, br. III 43004

  14. Static high-irradiance solar concentration by gradient-index optics

    Science.gov (United States)

    Kotsidas, Panagiotis; Modi, Vijay; Gordon, Jeffrey M.

    2011-10-01

    Novel solutions for realistic gradient-index (GRIN) lenses are presented, that create the possibility of nominally stationary photovoltaic concentrators capable of daylong averaged flux concentration levels of order 103. One transfers the burden of precision solar tracking from massive units on which numerous solar modules are mounted, to miniaturized mechanical components inside modules that are completely stationary. The best optical properties for this aim would appear to be perfect imaging - a case where imaging and nonimaging objectives coalesce because perfect imaging is non-trivially synonymous with attaining the fundamental limit to concentration. Our GRIN profiles surmount limitations of classical Luneburg solutions that resulted in GRIN lenses being deemed physically unattainable idealizations for sunlight. To wit, while preserving perfect imaging, our GRIN profiles eliminate the need for refractive indices near unity, markedly reduce the range of refractive indices required, and permit arbitrary focal length. They are also amenable to realistic materials and fabrication technologies. Raytrace simulations confirm that they offer an unprecedented solution to this problem - even accounting for chromatic aberration and misalignment. Eliminating massive precision tracking of large photovoltaic arrays in favor of precision cm-scale lens tracking inside the modules opens the possibility of rooftop CPV. The perception that high solar concentration is inseparably linked to massive trackers is supplanted here by a different paradigm.

  15. High-efficiency atomic entanglement concentration for quantum communication network assisted by cavity QED

    Science.gov (United States)

    Wang, Guan-Yu; Li, Tao; Deng, Fu-Guo

    2015-02-01

    Quantum entanglement is the key resource in quantum information processing, especially in quantum communication network. However, affected by the environment noise, the maximally entangled states usually collapse into nonmaximally entangled ones or even mixed states. Here we present two high-efficiency schemes to complete the entanglement concentration of nonlocal two-atom systems. Our first scheme is used to concentrate the nonlocal atomic systems in the partially entangled states with known parameters, and it has the optimal success probability. The second scheme is used to concentrate the entanglement of the nonlocal two-atom systems in the partially entangled states with unknown parameters. Compared with the other schemes for the entanglement concentration of atomic systems, our two protocols are more efficient and practical. They require only an ancillary single photon to judge whether they succeed or not, and they work in a heralded way with detection inefficiency and absence of sophisticated single-photon detectors in practical applications. Moreover, they are insensitive to both the cavity decay and atomic spontaneous emission.

  16. Dissolution of plutonium oxide in nitric acid at high hydrofluoric acid concentrations

    International Nuclear Information System (INIS)

    The dissolution of plutonium dioxide in nitirc acid (HNO3) at high hydrofluoric acid (HF) concentrations has been investigated. Dissolution rate curves were obtained using 12M HNO3 and HF at concentrations varying from 0.05 to 1.0 molar. The dissolution rate increased with HF concentration up to 0.2M and then decreased at higher concentrations. There was very little plutonium dissolved at 0.7 and 1.0M HF because of the formation of insoluble PuF4. Various oxidizing agents were added to 12M HNO3-1M HF dissolvent to oxidize Pu(IV) to Pu(VI) and prevent the formation of PuF4. Ceric [Ce(IV)] and silver [Ag(II)] ions were the most effective in dissolving PuO2. Although these two oxidants greatly increased the dissolution rate, the rates were not as rapid as those obtained with 12M HNO3-0.2M HF

  17. Dissolution of plutonium oxide in nitric acid at high hydrofluoric acid concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Kazanjian, A.R.; Stevens, J.R.

    1984-06-15

    The dissolution of plutonium dioxide in nitirc acid (HNO/sub 3/) at high hydrofluoric acid (HF) concentrations has been investigated. Dissolution rate curves were obtained using 12M HNO/sub 3/ and HF at concentrations varying from 0.05 to 1.0 molar. The dissolution rate increased with HF concentration up to 0.2M and then decreased at higher concentrations. There was very little plutonium dissolved at 0.7 and 1.0M HF because of the formation of insoluble PuF/sub 4/. Various oxidizing agents were added to 12M HNO/sub 3/-1M HF dissolvent to oxidize Pu(IV) to Pu(VI) and prevent the formation of PuF/sub 4/. Ceric (Ce(IV)) and silver (Ag(II)) ions were the most effective in dissolving PuO/sub 2/. Although these two oxidants greatly increased the dissolution rate, the rates were not as rapid as those obtained with 12M HNO/sub 3/-0.2M HF.

  18. Time evolution of atmospheric particle number concentration during high-intensity pyrotechnic events

    Science.gov (United States)

    Crespo, Javier; Yubero, Eduardo; Nicolás, Jose F.; Caballero, Sandra; Galindo, Nuria

    2014-10-01

    The Mascletàs are high-intensity pyrotechnic events, typical of eastern Spanish festivals, in which thousands of firecrackers are burnt at ground level in an intense, short-time (<8 min) deafening spectacle that generates short-lived, thick aerosol clouds. In this study, the impact of such events on air quality has been evaluated by means of particle number concentration measurements performed close to the venue during the June festival in Alicante (southeastern Spain). Peak concentrations and dilution times observed throughout the Mascletàs have been compared to those measured when conventional aerial fireworks were launched 2 km away from the monitoring site. The impact of the Mascletàs on the total number concentration of particles larger than 0.3 ?m was higher (maximum ˜2·104 cm-3) than that of fireworks (maximum ˜2·103 cm-3). The effect of fireworks depended on whether the dominant meteorological conditions favoured the transport of the plume to the measurement location. However, the time required for particle concentrations to return to background levels is longer and more variable for firework displays (minutes to hours) than for the Mascletàs (<25 min).

  19. Reconstruction of benzene exposure for the Pliofilm cohort (1936-1976) using Monte Carlo techniques.

    Science.gov (United States)

    Williams, Pamela R D; Paustenbach, Dennis J

    2003-04-25

    The current cancer slope factor and occupational standards for benzene are based primarily on studies of the rubber hydrochloride (Pliofilm) workers. Previous assessments of this cohort by Rinsky et al. (1981, 1987), Crump and Allen (1984), and Paustenbach et al. (1992) relied on different assumptions about the available industrial hygiene data and workplace practices and processes over time, thereby yielding significantly different estimates of annual benzene exposures for many jobs. Given the inherent limitations and uncertainties involved in estimating historical exposures for this cohort, a probabilistic approach was used to better characterize their likely degree of benzene exposure. Ambient air exposures to benzene were based, in part, on the distribution of air sampling data collected at the Pliofilm facilities and assumptions about how workplace concentrations probably decreased over time as the threshold limit value (TLV) was lowered. The likely uptake of benzene from dermal exposures was estimated based on probability distributions for several exposure factors, including surface area, contact rate and duration, and skin absorption. The assessment also quantitatively accounts for improved engineering controls, extended work hours, incomplete Pliofilm production, and the use and effectiveness of respirators over time. All original data and assumptions are presented in this assessment, as is all new information obtained through additional interviews of former workers. Estimated benzene exposures at the 50th and 95th percentiles are reported as equivalent 8-h time-weighted average (TWA) airborne concentrations for 13 job categories from 1936 to 1965 (Akron I and II facilities) and 1939 to 1976 (St. Mary's facility). Data indicate that estimated equivalent airborne benzene concentrations for St. Mary's workers were highest for four job categories (Neutralizer, Quencher, Knifeman, Spreader), typically ranging from about 50 to 90 ppm during 1939-1946 (lower during 1942-1945), and 10 to 40 ppm during 1947-1976 at the 50th percentile. These estimates are 2-3 times greater than for other jobs in the Pliofilm process, and about 1.5 times less than those estimated at the 95th percentile. Estimates of equivalent airborne benzene concentrations for Akron I and II were about 1.5 times higher than for St. Mary's, but there is less confidence in these estimates, given the lack of industrial hygiene monitoring data for these facilities. Study results suggest that Paustenbach et al. (1992) generally over-estimated exposures for those job categories that had the highest exposure by about a factor of two to four. On the other hand, it was concluded that Rinsky et al. (1981, 1987) under-predicted benzene exposures for most jobs, and Crump and Allen (1984) both under- and overpredicted benzene exposures, depending on the specific job category and time period. The new estimates presented in this analysis incorporate what is considered to be the most likely range of plausible exposure values, and, accordingly, provide a better characterization of the potential workplace exposures for this cohort. These data could be combined with current or future mortality information to calculate a new cancer potency factor or occupational health standard for benzene. PMID:12746133

  20. High activity concentrations of 210Pb and 7Be in sediments and their histories

    International Nuclear Information System (INIS)

    High activity concentrations of 210Pb and 7Be, in addition to 137Cs, were found in a rooftop deposit in Japan. This deposit had activities of about 5 Bq/g from 210Pb and 3.6 Bq/g from 7Be, an order of magnitude greater than typically found in field soils and lake and sea bottom sediments. It is clear that under certain conditions aerosol particles can accumulate in deposits with little or no mixing and dilution by silicate materials, and that subsequent processes and factors result in a heterogeneous distribution pattern of activity concentration on the Earth's surface. A simple model suggests that the history of an environmental sample can be estimated by using the activities of 210Pb and 7Be. -- Highlights: • High activity concentrations of 210Pb (5 Bq/g) and 7Be (3.6 Bq/g) were found in rooftop sediments in Japan. • Activity is an order of magnitude greater than in field soils and lacustrine and marine sediments. • The sample history is modeled using both nuclides