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1

Measurements of oxygen consumption in Mytilus edulis during exposure to, and recovery from, high sublethal concentrations of formaldehyde, benzene and phenol.  

Science.gov (United States)

1. The rate of oxygen consumption has been monitored continuously in M. edulis during acute exposure to high sublethal concentrations of formaldehyde, phenol and benzene and subsequent recovery periods of 96 hr. 2. The results are discussed in relation to changes in the electrochemical potential difference of sodium, the content of ATP and the tissue concentration of strombine. 3. After exposure to benzene and phenol, an increase in the rate of oxygen consumption that could not be explained by oxygen debt from the exposure period was observed. 4. Depression of the rate of oxygen consumption after exposure to formaldehyde may be explained by a reduced ability to extract oxygen from the water. 5. The pattern of oxygen consumption and behavioural responses, as well as the combined changes in the biochemical markers, were distinctly different in the three cases. PMID:1677879

Nordtug, T; Børseth, J F; Olsen, A; Zachariassen, K E

1991-01-01

2

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

Science.gov (United States)

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.

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

2013-04-01

3

A comprehensive study of benzene concentrations and emissions in Houston  

Science.gov (United States)

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.

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

2014-05-01

4

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

Science.gov (United States)

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.

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

2014-05-01

5

PREFRACTIONATION OF HIGH BENZENE PRECURSORS’ FEED FOR HYBRID REFORMER UNIT  

Directory of Open Access Journals (Sweden)

Full Text Available Benzene is toxic air pollutant and that’s why is set a constraint to 1% (v/v in gasoline. Refiners have to lower benzene in its gasoline pool components. High benzene contributors are reformate and FCC gasoline. Worldwide practice is to optimize the reformate benzene content. Some light crude oils, like Samgori from Georgia contain more fraction with boiling temperature interval from 60 to 85oC. This fraction is an indicator for benzene precursors content in gasoline. There is a possibility in LNB of prefractionation the reformer feed in columns K 105 from ADU and K1 from hydrotreating of catalytic reforming.A simulation was run with both aims: lowering benzene precursors and not to decrease reformer feed. The best solution is using K1 for its high potential reboiler’s duty.

K. Kirilov

2008-03-01

6

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

7

Mass spectrometric study of the high temperature chemistry of benzene  

International Nuclear Information System (INIS)

The high temperature pyrolysis of benzene was studied by monitoring the gas phase species flowing from a Knudsen reaction cell using modulated molecular beam mass spectrometry. The pyrolysis was studied at temperatures up to 19000C and pressures to 5 Torr. At low pressures hydrogen and carbonaceous deposits (soot) on the reaction cell wall were the dominant products. The disappearance of benzene at the low pressure limit was found to have an apparent activation energy of 82 +- 5 kcal/mole. The rate of carbon formation was determined indirectly from the difference between carbon from benzene flow into the reactor and products leaving the reactor, and good agreement was noted for carbon recovered from the reactor for extended experiments at 16000C. Carbon deposition is most efficient at low pressures; carbon deposition increases with pressure but the fraction of deposited carbon decreases as gas phase reactions become important. At higher pressures, where gas phase reactions dominate, C2H2, C4H2, C6H2, C8H6, C12H10, C12H8, H2, and carbon were the major products. The results suggest that the pyrolysis of benzene primarily involves the reaction of an excited benzene molecule to form a C12H12 intermediate which decomposes to yield C12H10 and other products. Isotopic eub>10 and other products. Isotopic exchange in C6H6-D2 and C6H6-C6D6 mixtures occurs at the same temperature as biomolecular reaction. At temperatures greater than 11000C more direct processes involving C6H4 appear to contribute. The pyrolysis occurs primarily by molecular processes, possibly due to the effects of wall-related reactions. 41 references, 16 figures, 1 table

8

High-efficiency plasma catalytic removal of dilute benzene from air  

International Nuclear Information System (INIS)

Achieving complete oxidation, good humidity tolerance and low energy cost is the key issue that needs to be addressed in plasma catalytic volatile organic compounds removal from air. For this purpose, Ag/HZSM-5 catalyst-packed dielectric barrier discharge using a cycled system composed of a storage stage and a discharge stage was studied. For dilute benzene removal from simulated air, Ag/HZSM-5 catalysts exhibit not only preferential adsorption of benzene in humid air at the storage stage but also almost complete oxidation of adsorbed benzene at the discharge stage. Five 'storage-discharge' cycles were examined, which suggests that Ag/HZSM-5 catalysts are very stable during the cycled 'storage-discharge' (CSD) plasma catalytic process. High oxidation rate of absorbed benzene as well as low energy cost can be achieved at a moderate discharge power. In an example of the CSD plasma catalytic remedy of simulated air containing 4.7 ppm benzene with 50% RH and 600 ml min-1 flow rate, the energy cost was as low as 3.7 x 10-3 kWh m-3 air. This extremely low energy cost to remove low-concentration pollutants from air undoubtedly makes the environmental applications of the plasma catalytic technique practical.

9

High-efficiency plasma catalytic removal of dilute benzene from air  

Energy Technology Data Exchange (ETDEWEB)

Achieving complete oxidation, good humidity tolerance and low energy cost is the key issue that needs to be addressed in plasma catalytic volatile organic compounds removal from air. For this purpose, Ag/HZSM-5 catalyst-packed dielectric barrier discharge using a cycled system composed of a storage stage and a discharge stage was studied. For dilute benzene removal from simulated air, Ag/HZSM-5 catalysts exhibit not only preferential adsorption of benzene in humid air at the storage stage but also almost complete oxidation of adsorbed benzene at the discharge stage. Five 'storage-discharge' cycles were examined, which suggests that Ag/HZSM-5 catalysts are very stable during the cycled 'storage-discharge' (CSD) plasma catalytic process. High oxidation rate of absorbed benzene as well as low energy cost can be achieved at a moderate discharge power. In an example of the CSD plasma catalytic remedy of simulated air containing 4.7 ppm benzene with 50% RH and 600 ml min{sup -1} flow rate, the energy cost was as low as 3.7 x 10{sup -3} kWh m{sup -3} air. This extremely low energy cost to remove low-concentration pollutants from air undoubtedly makes the environmental applications of the plasma catalytic technique practical.

Fan, Hong-Yu; Shi, Chuan; Li, Xiao-Song; Zhao, De-Zhi; Xu, Yong; Zhu, Ai-Min, E-mail: amzhu@dlut.edu.c [Laboratory of Plasma Physical Chemistry, Dalian University of Technology, Dalian 116024 (China)

2009-11-21

10

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

11

The treatment of gaseous benzene by two-phase partitioning bioreactors: a high performance alternative to the use of biofilters  

Energy Technology Data Exchange (ETDEWEB)

A 2-1 (1-1 working volume) two-phase partitioning bioreactor (TPPB) was used as an integrated scrubber/bioreactor in which the removal and destruction of benzene from a gas stream was achieved by the reactor's organic/aqueous liquid contents. The organic solvent used to trap benzene was n-hexadecane, and degradation of benzene was achieved in the aqueous phase using the bacterium Alcaligenes xylosoxidans Y234. A gas stream with a benzene concentration of 340 mg l{sup -1} at a flow rate of 0.414 l h{sup -1} was delivered to the system at a loading capacity of 140 g m{sup -3} h{sup -1}, and an elimination capacity of 133 g m{sup -3} h{sup -1} was achieved (the volume in this term is the total liquid volume of the TPPB). This elimination capacity is between 3 and 13 times greater than any benzene elimination achieved by biofiltration, a competing biological air treatment strategy. It was also determined that the evaluation of TPPB performance in terms of elimination capacity should include the cell mass present in the system, as this is a readily controllable quantity. A specific benzene utilization rate of 0.57 g benzene (g cells){sup -1} h{sup -1} was experimentally determined in a bioreactor with a cell concentration that varied dynamically between 0.2 and 1 g l{sup -1}. If it assumed that this specific benzene utilization rate (0.57 g g{sup -1} h{sup -1}) is independent of cell concentration, then a TPPB operated at high cell concentrations could potentially achieve elimination capacities several hundred times greater than those obtained with biofilters. (orig.)

Davidson, C.T.; Daugulis, A.J. [Dept. of Chemical Engineering, Queen' s Univ., Kingston, ON (Canada)

2003-07-01

12

High energy electron beam generation of oxidants for the treatment of benzene and toluene in the presence of radical scavengers  

International Nuclear Information System (INIS)

High energy electron beam irradiation of benzene and toluene in aqueous solution results in their destruction and the formation of highly oxidized reaction byproducts. The product distribution depends upon absorbed dose and pH and results from the reaction of benzene and toluene with the hydroxyl radical (OH·), followed by continued oxidation of intermediate by-products. The dose required to remove 99% (D0.99) of the benzene from solution, at an initial solute concentration of 17.0 ? M (1.3 mg l-1), was 95 krad. In presence of a known radical scavenger, i.e. 3.3 mM methanol, a dose of 1510 krad was required to achieve the same removal. Toluene showed greater removal, in the absence of methanol, than benzene under similar experimental condition. The D0.99 required to destroy an initial toluene concentration of 47.7 ?M (4.4 mg l-1) was 165 krad, whereas the D0.99 for an initial toluene concentration of 16.4 ? M, in the presence of 3.3 mM methanol, was 2074 krad. (Author)

13

Contribution to ambient benzene concentrations in the vicinity of petrol stations: Estimation of the associated health risk  

Science.gov (United States)

This work examines the contribution of petrol stations to the ambient benzene concentrations and attempts to estimate the possible health risks for the people living in the vicinity of such installations. Three monitoring sites (urban, suburban and rural) were used as reference points and the benzene concentrations were recorded at several distances along their perimeter. In order to evaluate the net contribution of the petrol station to the ambient benzene concentrations, the urban background concentration, measured by passive samplers and the contribution of the roads, estimated with both the COPERT and the linear source model CALINE 4, were deduced. Validation and optimization of the modeling system COPERT and CALINE4 was done in advance to ensure the reliability of the results. It seems that petrol stations have a significant contribution to ambient benzene concentrations in their vicinity. Finally, a risk assessment evaluation was attempted in terms of increased cancer risk due to the presence of the petrol stations in an area. The results show remarkable increase of the population risks in the vicinity, ranging from 3% to 21% in comparison to the population in the rest of the town.

Karakitsios, Spyros P.; Delis, Vasileios K.; Kassomenos, Pavlos A.; Pilidis, Georgios A.

14

Benzene Evolution Rates from Saltstone Prepared with 2X ITP Flowsheet Concentrations of Phenylborates and Heated to 85 Degrees C  

International Nuclear Information System (INIS)

The Saltstone Facility provides the final treatment and disposal of low level liquid wastes streams. At the Saltstone Facility, the waste is mixed with cement, flyash, and slag to form a grout, which is pumped into large concrete vaults where it cures. The facility started radioactive operations in June 1990. High Level Waste Engineering requested Savannah River Technology Center to determine the effect of TPB and its decomposition products (i.e., 3PB, 2PB, and 1PB) on the saltstone process. Previous testing performed by SRTC determined saltstone benzene evolution rates a function of ITP filtrate composition. Testing by the Thermal Fluids Laboratory has shown at design operation, the temperature in the Z-area vaults could reach 85 degrees Celsius. Saltstone asked SRTC to perform additional testing to determine whether curing at 85 degrees Celsius could change saltstone benzene evolution rates. This document describes the test performed to determine the effect of curing temperature on the benzene evolution rates

15

Coulombic and non-Coulombic fragmentation of highly charged benzene  

International Nuclear Information System (INIS)

Triple coincidence techniques have been used to measure the kinetic energies released (KER) upon fragmentation of C6Hq+6(q ? 4) molecules that are formed in collisions of benzene with 120 keV Ar8+ ions. The measured KER spectrum, which shows definitive structure rather than a continuous profile, is simulated using a simple Coulomb explosion model that accounts for all the permutations and combinations of states from which these fragment ions can be produced from the precursor molecular ion. The simulated spectrum correlates very well with the measurements but for disagreement in the low-KER regime that is attributed to non-Coulombic fragmentation pathways. Thus, in a single spectrum, both non-Coulombic and Coulombic regimes are accessed

16

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

Directory of Open Access Journals (Sweden)

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.

Abdulrahman Bahrami

2011-01-01

17

Sample preparation of environmental samples using benzene synthesis followed by high-performance LSC  

International Nuclear Information System (INIS)

Liquid scintillation counting (LSC) techniques have been widely employed as the detection method for determining environmental levels of tritium and 14C. Since anthropogenic and nonanthropogenic inputs to the environment are a concern, sampling the environment surrounding a nuclear power facility or fuel reprocessing operation requires the collection of many different sample types, including agriculture products, water, biota, aquatic life, soil, and vegetation. These sample types are not suitable for the direct detection of tritium of 14C for liquid scintillation techniques. Each sample type must be initially prepared in order to obtain the carbon or hydrogen component of interest and present this in a chemical form that is compatible with common chemicals used in scintillation counting applications. Converting the sample of interest to chemically pure benzene as a sample preparation technique has been widely accepted for processing samples for radiocarbon age-dating applications. The synthesized benzene is composed of the carbon or hydrogen atoms from the original sample and is ideal as a solvent for LSC with excellent photo-optical properties. Benzene synthesis followed by low-background scintillation counting can be applied to the preparation and measurement of environmental samples yielding good detection sensitivities, high radionuclide counting efficiency, and shorter preparation time. The method of benzene synthesis provides a unique apprf benzene synthesis provides a unique approach to the preparation of a wide variety of environmental sample types using similar chemistry for all samples

18

Indicators of benzene emissions and exposure in Bangkok street.  

Science.gov (United States)

Ambient benzene measurements were conducted for the first time at four air monitoring sites in the Bangkok metropolitan region (BMR), from January to December 2001. Analytical results show that the mean benzene concentrations range from 42.4 micro g/m(3) at the Din Daeng urban site to 15.1 micro g/m(3) at the Chaeng Wattana suburban site. The monitoring results show that at a larger distance from the roadside or a higher level from the street surface, the level of benzene decreases. Analysis of the ambient benzene concentrations was carried out with reference to meteorological influences and traffic density. In traffic analysis, the combined effects of street topography and traffic flows established high impact on the overall benzene concentration in Bangkok. Statistical analysis shows good correlations of blood benzene levels and trans, trans-muconic acid with ambient benzene and demonstrated substantial exposure from traffic. PMID:12804513

Leong, Shing Tet; Laortanakul, Preecha

2003-07-01

19

Tris(triazolo)benzene and its derivatives: high-density energetic materials.  

Science.gov (United States)

High-performance explosives: Tris(triazolo)benzene was synthesized and converted to its trinitro and trichloro derivatives (see scheme; R=NO(2), Cl). The heats of formation of this "high-nitrogen" compounds were calculated and combined with experimentally determined densities to determine detonation pressures and velocities. They exhibit high density, good thermal stability, high heats of formation, and moderate to good detonation properties. PMID:22945830

Thottempudi, Venugopal; Forohor, Farhad; Parrish, Damon A; Shreeve, Jean'ne M

2012-09-24

20

Benzene hematotoxicity and leukemogenesis  

Energy Technology Data Exchange (ETDEWEB)

Benzene is ubiquitous and accepted as a human carcinogen by regulatory agencies. Proposed regulations assume without proof that the carcinogenic response to benzene exposure is one hit implying a linear with no threshold. There is no solid experimental proof for this concept. This research involves exposure of CBA/Ca male mice to benzene vapor in varying concentrations. Exposure to 300 ppm 6 hrs/day, 5 days/week, for 16 weeks is highly leukemogenic. Exposure for the same time to 100 ppm is also leukemogenic. Concentrations from 25 ppm to 400 ppm 6 hrs/day, 5 days/week, for 10 exposures produce an increasing lymphopenia. Exposure to 100 ppm for the same exposure time produces anemia, decrease in stem cell content of marrow, and marrow cellularity. Further dose-effect studies are required to test the one hit hypothesis and to determine whether the same integral dose of benzene administered over variable exposure has the same or different biological responses. It is of concern that biologic effects are observed at 25 ppm only 2.5 times the present permissible time-weighted average exposure during a working day and research by others has demonstrated an effect (noncarcinogenic) at 10 ppm. 18 references, 1 figure.

Cronkite, E.P.

1986-01-01

 
 
 
 
21

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)

22

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Abdulrahman Bahrami; Hosien Mahjub; Marzieh Sadeghian; Farideh Golbabaei

2011-01-01

23

Numerical model investigation for potential methane explosion and benzene vapor intrusion associated with high-ethanol blend releases.  

Science.gov (United States)

Ethanol-blended fuel releases usually stimulate methanogenesis in the subsurface, which could pose an explosion risk if methane accumulates in a confined space above the ground where ignitable conditions exist. Ethanol-derived methane may also increase the vapor intrusion potential of toxic fuel hydrocarbons by stimulating the depletion of oxygen by methanotrophs, and thus inhibiting aerobic biodegradation of hydrocarbon vapors. To assess these processes, a three-dimensional numerical vapor intrusion model was used to simulate the degradation, migration, and intrusion pathway of methane and benzene under different site conditions. Simulations show that methane is unlikely to build up to pose an explosion hazard (5% v/v) if diffusion is the only mass transport mechanism through the deeper vadose zone. However, if methanogenic activity near the source zone is sufficiently high to cause advective gas transport, then the methane indoor concentration may exceed the flammable threshold under simulated conditions. During subsurface migration, methane biodegradation could consume soil oxygen that would otherwise be available to support hydrocarbon degradation, and increase the vapor intrusion potential for benzene. Vapor intrusion would also be exacerbated if methanogenic activity results in sufficiently high pressure to cause advective gas transport in the unsaturated zone. Overall, our simulations show that current approaches to manage the vapor intrusion risk for conventional fuel released might need to be modified when dealing with some high ethanol blend fuel (i.e., E20 up to E95) releases. PMID:24354291

Ma, Jie; Luo, Hong; Devaull, George E; Rixey, William G; Alvarez, Pedro J J

2014-01-01

24

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

International Nuclear Information System (INIS)

(>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)

25

Benzene: questions and answers  

International Nuclear Information System (INIS)

This information booklet is intended to inform residents near natural gas dehydration facilities about benzene and its levels in the atmosphere. It was issued following the federal government's decision to place benzene on its Priority Substances List and to require industry to establish means for reducing benzene emissions from natural gas dehydrators and to inform residents about benzene emissions from glycol dehydration facilities. Accordingly, the booklet explains what benzene is (a colourless flammable liquid component of hydrocarbons) how it gets into the air (during gasoline refining, vehicle refueling and the production of steel and petrochemicals), the associated health hazards (a recognized carcinogen, causing an increased incidence of leukemia in concentrations of 100 parts per million), defines a glycol dehydrator (a facility built at or near some natural gas fields for the removal of water from the natural gas to prevent corrosion and freezing of pipelines), and enumerates the steps that are being taken to reduce benzene levels in the air (benzene levels in gasoline have been reduced, along with benzene emissions from petrochemical plants, refineries, steel plants and glycol dehydrators by 54 per cent to date; this will rise to 90 per cent by 2005). In addition to these actions, industry plans call for all existing glycol dehydrators within 750 metres of any permanent residence to be limited to benzene emissions of no more than three tonnes per year before 2001; new glycol dehydrators after that date will be expected to have benzene emissions reduced to the lowest level that can be practically achieved

26

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...are overexposed to high concentrations...concentration might be high without proper safety...Benzene vapor may form explosive mixtures in air...879 3. Vapor Density (air=1): 2...Its vapors can form explosive mixtures. All...Precautions A. High exposure to...

2010-07-01

27

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.)

28

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...is primarily an inhalation hazard. Systemic...and leukemia. Inhalation of high concentrations...sensation in the eye. Inhalation of high concentrations...for benzene's toxic effects which...persisting abnormalities caused by exposure to...following marrow injury), and detection...

2010-07-01

29

Radiolysis ob benzene, toluene and phenol aqueous solutions utilizing high energy electron beam; Radiolisis de benceno, tolueno y fenol en solucion acuosa utilizando haces de electrones  

Energy Technology Data Exchange (ETDEWEB)

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 {mu}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)

Gonzalez Vanderhaghen, D.E

1998-12-31

30

High concentration agglomerate dynamics at high temperatures.  

Science.gov (United States)

The dynamics of agglomerate aerosols are investigated at high solids concentrations that are typical in industrial scale manufacture of fine particles (precursor mole fraction larger than 10 mol %). In particular, formation and growth of fumed silica at such concentrations by chemical reaction, coagulation, and sintering is simulated at nonisothermal conditions and compared to limited experimental data and commercial product specifications. Using recent chemical kinetics for silica formation by SiCl4 hydrolysis and neglecting aerosol polydispersity, the evolution of the diameter of primary particles (specific surface area, SSA), hard- and soft-agglomerates, along with agglomerate effective volume fraction (volume occupied by agglomerate) is investigated. Classic Smoluchowski theory is fundamentally limited for description of soft-agglomerate Brownian coagulation at high solids concentrations. In fact, these high concentrations affect little the primary particle diameter (or SSA) but dominate the soft-agglomerate diameter, structure, and volume fraction, leading to gelation consistent with experimental data. This indicates that restructuring and fragmentation should affect product particle characteristics during high-temperature synthesis of nanostructured particles at high concentrations in aerosol flow reactors. PMID:17107027

Heine, M C; Pratsinis, S E

2006-11-21

31

High-concentration tritium sensor  

Energy Technology Data Exchange (ETDEWEB)

A bi-layer device was fabricated and tested for the direct collection of electrons emitted by tritium beta decay. The sensor functions at high pressures and concentrations where previously no simple and cost effective direct measurement technique existed for tritium. A polished KOVAR{trademark} (Fe-Ni-Co alloy) rod was coated with a 1-{mu}m thick insulating layer of alumina using electron-beam evaporation, physical vapor deposition (PVD) of aluminum with oxygen dosing. The alumina deposition process was optimized to minimize pinholes and obtain a stable coating with high resistivity. The detector exhibited a nanoampere electrical response over a few decades of tritium concentration, up to pure tritium at 200 kPa. The sensor has been in service for several months now without showing signs of degradation and no discernible physical damage or change in efficiency or linearity has been observed.

Paglieri, S. N. (Stephen N.); Richmond, S. (Scott); Snow, R. C. (Ronny C.); Morris, J. S. (John S.); Tuggle, D. G. (Dale Glenn)

2004-01-01

32

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

Science.gov (United States)

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.

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

2014-08-01

33

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

Science.gov (United States)

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 station attendants than any other scenario. PMID:24945191

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

2014-06-01

34

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

35

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)

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.

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

36

A bioactive foamed emulsion reactor for the treatment of benzene-contaminated air stream.  

Science.gov (United States)

An adapted bioactive foamed emulsion bioreactor for the treatment of benzene vapor has been developed. In this reactor, bed clogging was resolved by bioactive foam as a substitute of packing bed for interfacial contact of liquid to gaseous phase. The pollutant solubility has been increased using biocompatible organic phase in liquid phase and this reactor can be applied for higher inlet benzene concentration. Experimental results showed a benzene elimination capacity (EC) of 220 g m(-3) h(-1) with removal efficiency (RE) of 85% for benzene inlet concentration of 1-1.2 g m(-3) at 15 s gas residence time in bioreactor. Assessment of benzene concentration in liquid phase showed that a significant amount of transferred benzene mass has been biodegraded. By optimizing the operational parameters of bioreactor, continuous operation of bioreactor with high EC and RE was demonstrated. With respect to the results, this reactor has the potential to be applied instead of biofilter and biotrickling filters. PMID:19421781

Ghorbani Shahna, Farshid; Golbabaei, Faride; Hamedi, Javad; Mahjub, Hossein; Darabi, Hossein Reza; Shahtaheri, Seyed Jamaleddin

2010-02-01

37

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...removal. (j) Communication of benzene hazards...OSHA's Hazard Communication Standard, 29 CFR...D) The name, social security number...in which benzene affects your health. ...Extinguishing Media: Carbon dioxide...concentrations can affect central...

2010-07-01

38

Solubilities of Toluene, Benzene and TCE in High-Biomass Systems  

Energy Technology Data Exchange (ETDEWEB)

We report measurements of solubility limits for benzene, toluene, and TCE in systems that contain varying levels of biomass up to 0.13 g/mL. The solubility limit increased from 20 to 48 mM when biomass (in the form of yeast) was added to aqueous batch systems containing benzene. The toluene solubility limit increased from 4.9 to greater than 20 mM. For TCE, the solubility increased from 8 mM to more than 1000 mM. Solubility for TCE was most heavily impacted by biomass levels, changing by two orders of magnitude.

Barton, John W. [Battelle Eastern Science & Technology Center; Vodraska, Christopher D [ORNL; Flanary, Sandie A. [Oak Ridge National Laboratory (ORNL); Davison, Brian H [ORNL

2008-01-01

39

High-spin electronic states of lanthanide-arene complexes: Nd(benzene) and Nd(naphthalene)  

Science.gov (United States)

Neodymium (Nd) complexes of benzene and naphthalene were synthesized in a laser-ablation supersonic molecular beam source. High-resolution electron spectra of these complexes were obtained using pulsed-field ionization zero electron kinetic energy (ZEKE) spectroscopy. Second-order Møller-Plesset perturbation calculations were employed to aid spectral and electronic-state assignments. The adiabatic ionization energies were measured to be 38 081 (5) cm-1 for Nd(benzene) and 37 815 (5) cm-1 for Nd(naphthalene). For the Nd(benzene) complex, the observed frequencies of 831 and 286 cm-1 were assigned to C-H out-of-plane bending and Nd+-C6H6 stretching modes in the 6A1 ion state and 256 cm-1 to the Nd-C6H6 stretching mode in the 7A1 neutral state. To confirm these assignments, the ZEKE spectrum of the deuterated species was recorded, and the corresponding vibrational frequencies were measured to be 710 and 277 cm-1 in the ion state and 236 cm-1 in the neutral state. For the Nd(naphthalene) complex, the observed vibrational modes were C10H8 bending (394 cm-1), Nd+-C10H8 stretching (286 and 271 cm-1), Nd+-C10H8 bending (80 cm-1), and C10H8 twisting (105 cm-1) in the 6A' ion state and metal-ligand bending (60 cm-1) and ligand twisting (55 cm-1) in the 7A' neutral state. The formation of the ground state of the Nd(benzene) complex requires 4f --> 5d and 6s --> 5d electron excitation of the Nd atom, whereas the formation of the ground state of Nd(naphthalene) involves the 6s --> 5d electron promotion.

Lei, Yuxiu; Wu, Lu; Sohnlein, Bradford R.; Yang, Dong-Sheng

2012-05-01

40

46 CFR Appendix C to Subpart C to... - Medical Surveillance Guidelines for Benzene  

Science.gov (United States)

...is primarily an inhalation hazard. Systemic...and leukemia. Inhalation of high...sensation in the eye. Inhalation of high concentrations...for benzene's toxic effects which...persisting abnormalities caused by exposure to...following marrow injury) and detection...

2010-10-01

 
 
 
 
41

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)

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.

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

2009-03-01

42

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

Science.gov (United States)

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

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

2014-08-15

43

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

44

Fuel Dependence of Benzene Pathways  

Energy Technology Data Exchange (ETDEWEB)

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.

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

2008-07-14

45

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

Science.gov (United States)

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

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

2011-07-22

46

Design and development of a high-concentration photovoltaic concentrator  

Energy Technology Data Exchange (ETDEWEB)

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.

Hodge, R C

1982-04-01

47

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

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 ...

Dundas, Daniel

2012-01-01

48

A novel malonamide grafted polystyrene-divinyl benzene resin for extraction, pre-concentration and separation of actinides  

International Nuclear Information System (INIS)

A new chelating polymeric extraction chromatographic resin was prepared by chemical anchoring of N,N'-dimethyl-N,N'-dibutyl malonamide (DMDBMA) with chloromethylated Merrifield resin. The grafted resin exhibited stronger binding for hexavalent and tetravalent actinides such as U(VI), Th(IV) and Pu(IV) over trivalent actinides, viz. Am(III) and Pu(III). Batch studies on solid phase extraction performed over a wide range of acid solution (0.01-6 M HNO3) revealed that ternary mixer of uranium, americium and plutonium or thorium, americium and plutonium could be separated from each other at 1 M HNO3. Desorption of U(VI), Pu(IV) and Am(III) from the loaded resin was efficiently carried out using 0.1 M ?-HIBA, 0.25 M oxalic acid and 0.01 M EDTA, respectively. Quantitative pre-concentration of actinide ions such as Th(IV) and U(VI) was possible from 3 M HNO3 solution. The practical utility of the grafted resin was evaluated by uranium sorption measurements in several successive cycles. The sorption efficiency of the resin with respect to uranyl ion remained unchanged even after 30 days of continuous use. The surface morphology of the resin was monitored with the help of scanning electron microscopy (SEM) technique

49

Hydrogenation of benzene-toulene-xylene fraction of coke-chemical production for a preparation of ecologically pure high octane component for vehicle gasoline  

Directory of Open Access Journals (Sweden)

Full Text Available  Process for a hydrogenation of benzene-toulene-xylene fraction of coke-chemical production for a preparation of ecologically pure high octane component for vehicle gasoline has been described. Based on the results obtained, optimal conditions for carrying out the process were recommended.

?.?. ???????

2005-01-01

50

Characterization of anaerobic benzene-degrading cultures  

Energy Technology Data Exchange (ETDEWEB)

Microbial populations in 2 benzene-degrading consortia were characterized on a physiological and molecular level. Methanogenic and nitrate-reducing cultures were examined. The shortest doubling time of 8 to 9 days was observed in the nitrate-reducing cultures while the methanogenic cultures showed the highest substrate concentration and the maximum absolute rates of benzene degradation. The methanogenic culture also had 5 bacterial 16S rRNA sequences, of which 1 resembled a clone previously found in a sulphate-reducing benzene-degrading culture. Four bacterial and no archaeal 16S rRNA sequences were found in the nitrate-reducing culture. One clone was phylogenetically similar to both Azoarcus and Dechloromonas species. The study also isolated and characterized pure cultures that could anaerobically biodegrade benzene. Two cultures were successfully isolated from a nitrate-reducing enrichment culture. Both were capable of anaerobic benzene, toluene and benzoate degradation under nitrate-reducing conditions. The isolated pseudomonas was capable of aerobic benzene degradation and hydrogen utilization under nitrate-reducing conditions. The isolated and unidentified eubacterium clone did not appear to grow on any of the tested substrates. The study also identified the key metabolic processes in anaerobic benzene degradation. Studies with carbon isotopes showed that under methanogenic conditions, a pathway exists where benzene undergoes hydroxylation to phenol. Intermediates of benzene degradation were identified for nitrate-reducing conditions. This study presents the first evidence for a pathway where benzene undergoes methylation to toluene and further transformation to benzoate.

Ulrich, A.C.

2004-07-01

51

Modelling and computational fluid dynamic behaviour of a biofilter treating benzene.  

Science.gov (United States)

Biofiltration of an air stream containing benzene has been studied in a laboratory biofilter packed with a mixture of compost, sugar cane bagasse and GAC. In this study, the overall performance of a biofilter has been evaluated in terms of its elimination capacity by using 3-D mesh techniques. The overall results indicate that the agreement between experimental data and estimated model predictions is excellent for benzene. The benzene concentration profiles along the depth of biofilter have also been determined using a convection-diffusion reactor (CDR) model and computational fluid dynamic (CFD) technique. At low flow rates and low concentrations of benzene, the concentration profile throughout the biofilter shows good agreement with CDR model and it becomes more curved and resembles typical decay. Combined analysis of experimental results with CDR model and the CFD shows that the profile of benzene at low concentration becomes more curved and then linear at high concentration. The benzene profiles obtained by CFD are within 5% accuracy of experimental results. The CDR and CFD models are found to be able to predict concentration profiles preciously with depth under the experimental conditions. PMID:23026335

Rahul; Mathur, Anil Kumar; Bala, Shashi; Majumder, Chandrajitbalo

2012-12-01

52

Concentration phenomena in high dimensional geometry  

Directory of Open Access Journals (Sweden)

Full Text Available The purpose of this note is to present several aspects of concentration phenomena in high dimensional geometry. At the heart of the study is a geometric analysis point of view coming from the theory of high dimensional convex bodies. The topic has a broad audience going from algorithmic convex geometry to random matrices. We have tried to emphasize different problems relating these areas of research. Another connected area is the study of probability in Banach spaces where some concentration phenomena are related with good comparisons between the weak and the strong moments of a random vector.

Guédon Olivier

2014-01-01

53

Mechanistic considerations in benzene physiological model development  

Energy Technology Data Exchange (ETDEWEB)

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.

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

54

Hydrogeologic characterization and assessment of bioremediation of chlorinated benzenes and benzene in wetland areas, Standard Chlorine of Delaware, Inc. Superfund Site, New Castle County, Delaware, 2009-12  

Science.gov (United States)

Wetlands at the Standard Chlorine of Delaware, Inc. Superfund Site (SCD) in New Castle County, Delaware, are affected by contamination with chlorobenzenes and benzene from past waste storage and disposal, spills, leaks, and contaminated groundwater discharge. In cooperation with the U.S. Environmental Protection Agency, the U.S. Geological Survey began an investigation in June 2009 to characterize the hydrogeology and geochemistry in the wetlands and assess the feasibility of monitored natural attenuation and enhanced bioremediation as remedial strategies. Groundwater flow in the wetland study area is predominantly vertically upward in the wetland sediments and the underlying aquifer, and groundwater discharge accounts for a minimum of 47 percent of the total discharge for the subwatershed of tidal Red Lion Creek. Thus, groundwater transport of contaminants to surface water could be significant. The major contaminants detected in groundwater in the wetland study area included benzene, monochlorobenzene, and tri- and di-chlorobenzenes. Shallow wetland groundwater in the northwest part of the wetland study area was characterized by high concentrations of total chlorinated benzenes and benzene (maximum about 75,000 micrograms per liter [?g/L]), low pH, and high chloride. In the northeast part of the wetland study area, wetland groundwater had low to moderate concentrations of total chlorinated benzenes and benzene (generally not greater than 10,000 ?g/L), moderate pH, and high sulfate concentrations. Concentrations in the groundwater in excess of 1 percent of the solubility of the individual chlorinated benzenes indicate that a contaminant source is present in the wetland sediments as dense nonaqueous phase liquids (DNAPLs). Consistently higher contaminant concentrations in the shallow wetland groundwater than deeper in the wetland sediments or the aquifer also indicate a continued source in the wetland sediments, which could include dissolution of DNAPLs and desorption from the sediments.

Lorah, Michelle M.; Walker, Charles W.; Baker, Anna C.; Teunis, Jessica A.; Majcher, Emily H.; Brayton, Michael J.; Raffensperger, Jeff; Cozzarelli, Isabelle M.

2014-01-01

55

High Concentration Silicon Photovoltaic Cell Development.  

Science.gov (United States)

The objective of this study is to develope practical semiconductor photocells: 1) for use is high concentration system (at leat 25 suns at air-mass-one), 2) having 18% or more efficiency, 3) using state-of-the-art silicon material and device technology, a...

G. Allendorf, R. Frank, J. Goodrich, W. Matthei

1980-01-01

56

Cellulase Inhibition by High Concentrations of Monosaccharides  

DEFF Research Database (Denmark)

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.

Hsieh, Chia-Wen; Cannella, David

2014-01-01

57

Determination of the unburnt benzene in the autovehicular emission  

International Nuclear Information System (INIS)

The exhaust benzene emission from passengers cars has been characterized using a methodology based on deuterated compounds. European vehicles were fueled with a gasoline containing a total benzene concentration (hydrogenated plus deuterated) ranging from 0.98 to 2.75 v/v. Since deuterated benzene at the tail pipe can be present only as unburnt from the fuel, calculating the relative ratio of hydro/deutero compound, the unreacted benzene and that formed in the combustion process can be recognized and the corresponding percentage of unburnt compound qualified. This approach allowed to confirm the benzene formation in the catalytic converter. The experimental data, both for a vehicle equipped with a three way catalytic muffler and for a carburetor car, fit the expected curve describing the percentage of emitted unburnt benzene (considered with respect to the total amount of benzene in the exhaust gas) vs. the benzene content of the gasoline

58

Direct Infrared Absorption Spectroscopy of Benzene Clusters  

Science.gov (United States)

In order to find out the global minimum structure of the benzene dimer we engaged in a series of low (0.5 cm-1) and high (0.015 cm-1) resolution direct absorption infrared measurements of benzene clusters in the 3.3 micron region of the fundamental C-H stretch. The benzene clusters are produced in a continuous supersonic expansion generated by a 24-cm long slit nozzle using helium, argon or neon as carrier gases. Low resolution spectra show a red shift in the CH stretch spectral region which is found to increase with increase in cluster size. When using argon, high resolution spectrum reveals new weak absorption lines between the strongest monomer lines, attributed to the Ar-Benzene complexe. Currently we are involved in recording the high resolution spectrum of the benzene dimer using helium as a carrier gas. R. Georges, A. Bonnamy, M Decroi and J Boissoles, {Molecular Physics 100,1551, (2002)

Chandrasekaran, Vijayanand; Biennier, L.; Georges, R.; Arunan, E.; Reddy, K. P. J.

2009-06-01

59

Biomarkers of human exposure to benzene  

Energy Technology Data Exchange (ETDEWEB)

Three biomarkers for benzene exposure were developed. The first biomarker, muconic acid in urine, results from the ring opening of a benzene metabolite. A gas chromatography/mass spectroscopy (GC/MS) assay was developed to measure urinary muconic acid, and the analyte in urine samples from workers occupationally exposed to benzene was determined. Workers exposed to benzene concentrations as low as 4.4 ppm over an 8-h day showed higher urinary muconic acid concentrations than did any control individual (p < .005). The second biomarker, S-phenylcysteine (SPC) in hemoglobin (Hb), results from the addition of benzene oxide to a cysteine sulfhydryl group. A GC/MS assay was developed to measure SPC in the blood of F344/N rats and B67C3F mice exposed to benzene by inhalation. The cysteine moiety on rat Hb is at a more accessible site than on Hb of mice or humans, and rats showed considerably higher levels of SPC than did mice. As yet, we have been unable to detect SPC in the globin of humans occupationally exposed to benzene. The third biomarker is SPC in albumin. In humans occupationally exposed to average concentrations of 0, 4.4, 8.4, and 23.1 ppm benzene, 8 h/d, 5 d/wk, SPC increased in the exposed groups linearly, giving a statistically significant slope (p < .001) of 0.044 [+-] 0.008 pmol/mg albumin/ppm. The assay for SPC is arduous and often imprecise; assuming these difficulties can be overcome, muconic acid in urine and SPC in albumin may be useful for accurately determining benzene exposure. 25 refs., 4 figs., 1 tab.

Bechtold, W.E.; Henderson, R.F. (Inhalation Toxicology Research Institute, Albuquerque, NM (United States))

1993-01-01

60

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese 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.

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

1227-12-01

 
 
 
 
61

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese 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.

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

62

Direct arylation of benzene with aryl bromides using high-temperature/high-pressure process windows: expanding the scope of C-H activation chemistry.  

Science.gov (United States)

A detailed investigation on the direct arylation of benzene with aryl bromides by using first-row transition metals under high-temperature/high-pressure (high-T/p) conditions is described. By employing a parallel reactor platform for rapid reaction screening and discovery at elevated temperatures, various metal/ligand/base combinations were evaluated for their ability to enable biaryl formation through C-H activation. The combination of cobalt(III) acetylacetonate and lithium bis(trimethylsilyl)amide was subjected to further process intensification at 200?°C (15?bar), allowing a significant reduction of the catalyst/base loading and a dramatic increase in catalytic efficiency (turnover frequency) by a factor of 1000 compared to traditional protocols. The high-throughput screening additionally identified novel nickel- and copper-based metal/ligand combinations that favored an amination pathway competing with C-H activation, with the addition of ligands, such as 1,10-phenanthroline, having a profound influence on the selectivity. In addition to metal-based catalysts, high-T/p process windows were also successfully applied to transition-metal-free systems, utilizing 1,10-phenanthroline as organocatalyst. PMID:22396386

Pieber, Bartholomäus; Cantillo, David; Kappe, C Oliver

2012-04-16

63

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

64

Structure of ionic liquid-benzene mixtures.  

Science.gov (United States)

Neutron diffraction has been used to investigate the structure of liquid mixtures of 1,3-dimethylimidazolium hexafluorophosphate with benzene. Two concentrations of benzene were investigated, namely, 33 mol % and 67 mol %, and show similar structures in each case. The presence of benzene significantly alters the ionic liquid structure, in particular, in the cation-cation interactions, in agreement with the single-crystal structure described recently (Holbrey, J. D.; Reichert, W. M.; Nieuwenhuyzen, M.; Sheppard, O.; Hardacre, C.; Rogers, R. D. Chem. Commun. 2003, 476). In each case, the data was analyzed using an empirical potential structure refinement process. PMID:16851130

Deetlefs, Maggel; Hardacre, Christopher; Nieuwenhuyzen, Mark; Sheppard, Oonagh; Soper, Alan K

2005-02-01

65

Diverse microbial species survive high ammonia concentrations  

Science.gov (United States)

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.

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

2012-04-01

66

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

67

Benzene release. status report  

Energy Technology Data Exchange (ETDEWEB)

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.

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

68

Fingering phenomena at high surfactant concentrations  

Science.gov (United States)

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.

Matar, Omar K.

2005-11-01

69

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

70

On the origin of benzene, toluene, ethylbenzene and xylene in extra virgin olive oil.  

Science.gov (United States)

Concentrations of benzene, toluene, C2-benzenes and styrene were determined in olives and the oils produced thereof, as well as at various intermediate steps during production. Concentrations were compared to those found in samples of air taken from the olive grove and the olive mills. In an exposition experiment in the laboratory, olives absorbed aromatic compounds, approaching saturation corresponding to the partition coefficient between air and oil. However, concentrations in olives delivered to the mills were 4-10 times higher than expected from the analysis of the air in the olive grove. In the olive mills, concentrations were increased further by a factor of up to 2 because of uptake from air which contained high concentrations of aromatics. Styrene concentrations strongly increased during storage of crushed olives at ambient temperature, which confirms the hypothesis that styrene is a product of metabolism. PMID:7785357

Biedermann, M; Grob, K; Morchio, G

1995-04-01

71

Dielectric Relaxation of Polar Molecules in Benzene Medium at Microwave  

Directory of Open Access Journals (Sweden)

Full Text Available The dielectric constant (?’ and loss(?”of polar liquids in solutions of benzene have been determined at room temperature (270Cat fixed microwave frequency (10.15 GHz. It is observed that dielectric constant and loss varies with concentration linearly. The studies report a determination of relaxation time (? electric dipole moment (? of Polar liquids in benzene solution at room temperature.

S. B. Gedam

2013-07-01

72

Dielectric Relaxation of Polar Molecules in Benzene Medium at Microwave  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The dielectric constant (?’) and loss(?”)of polar liquids in solutions of benzene have been determined at room temperature (270C)at fixed microwave frequency (10.15 GHz). It is observed that dielectric constant and loss varies with concentration linearly. The studies report a determination of relaxation time (?) electric dipole moment (?) of Polar liquids in benzene solution at room temperature.

Gedam, S. B.; Suryavanshi, B. M.

2013-01-01

73

High efficiency photovoltaic roof tile with static concentrator  

Energy Technology Data Exchange (ETDEWEB)

The application of static concentrators (as distinct from tracking concentrators) in solar modules allows significant cost reductions through replacement of expensive solar cells with inexpensive concentrating elements such as lenses and reflectors. Incorporation of static concentrators into standard roof tiles has been hampered by bulky designs offering low concentration ratios or poor collection efficiencies. This paper describes a three dimensional design of the static concentrator which allows relatively high concentration ratios while maintaining high collection efficiencies in a slim line package. Use of bi facial cells and a material of high refractive index allows an increase in the maximum concentration ratio achieved. The concentration ratio of the current design exceeds 3.5 with cells representing only 25 percent of the area of the module. (author). 5 figs., 6 refs.

Boesen, M.; Bowden, S. [New South Wales Univ., Kensington, NSW (Australia). Centre for Photovoltaic Devices and Systems

1994-12-31

74

Kriged and modeled ambient air levels of benzene in an urban environment: an exposure assessment study  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background There is increasing concern regarding the potential adverse health effects of air pollution, particularly hazardous air pollutants (HAPs. However, quantifying exposure to these pollutants is problematic. Objective Our goal was to explore the utility of kriging, a spatial interpolation method, for exposure assessment in epidemiologic studies of HAPs. We used benzene as an example and compared census tract-level kriged predictions to estimates obtained from the 1999 U.S. EPA National Air Toxics Assessment (NATA, Assessment System for Population Exposure Nationwide (ASPEN model. Methods Kriged predictions were generated for 649 census tracts in Harris County, Texas using estimates of annual benzene air concentrations from 17 monitoring sites operating in Harris and surrounding counties from 1998 to 2000. Year 1999 ASPEN modeled estimates were also obtained for each census tract. Spearman rank correlation analyses were performed on the modeled and kriged benzene levels. Weighted kappa statistics were computed to assess agreement between discretized kriged and modeled estimates of ambient air levels of benzene. Results There was modest correlation between the predicted and modeled values across census tracts. Overall, 56.2%, 40.7%, 31.5% and 28.2% of census tracts were classified as having 'low', 'medium-low', 'medium-high' and 'high' ambient air levels of benzene, respectively, comparing predicted and modeled benzene levels. The weighted kappa statistic was 0.26 (95% confidence interval (CI = 0.20, 0.31, indicating poor agreement between the two methods. Conclusions There was a lack of concordance between predicted and modeled ambient air levels of benzene. Applying methods of spatial interpolation for assessing exposure to ambient air pollutants in health effect studies is hindered by the placement and number of existing stationary monitors collecting HAP data. Routine monitoring needs to be expanded if we are to use these data to better assess environmental health risks in the future.

Lai Dejian

2011-03-01

75

Measuring the protium concentration in highly concentrated heavy water by IR spectrometry  

International Nuclear Information System (INIS)

A new technique to measure the protium and deuterium concentrations (aH and aD) in heavy water by infrared (IR) spectrometry is presented. This technique gives a possibility to determine the absolute protium concentration in highly concentrated heavy water with the relative error ±1%. (authors)

76

Source identification of benzene emissions in Texas City using an adjoint neighborhood scale transport model  

Science.gov (United States)

During the "Formaldehyde and Olefins from Large Industrial Sources" (FLAIR) study in 2009, the Aerodyne Research Inc. (ARI) mobile laboratory performed real-time in situ measurements of VOCs, NOx and HCHO in Texas City, TX on May 7, 2009 from 11 am to 3 pm. This high resolution dataset collected in a predominantly industrial area provides an ideal test bed for advanced source attribution. Our goal was to identify and quantify emission sources within the largest facility in Texas City most likely responsible for measured benzene concentrations. For this purpose, fine horizontal resolution (200 m x 200 m) 4D variational (4Dvar) inverse modeling was performed by running the HARC air quality transport model in adjoint mode based on ambient concentrations measured by the mobile laboratory. The simulations were conducted with a horizontal domain size of 4 km x 4 km for a four-hour period (11 am to 3 pm). Potential emission unit locations within the facility were specified using a high spatial resolution digital model of the largest industrial complex in the area. The HARC model was used to infer benzene emission rates from all potential source locations that would account for the benzene concentrations measured by the Aerodyne mobile laboratory in the vicinity of the facility. A Positive Matrix Factorization receptor model was also applied to the concentrations of other compounds measured by the mobile lab to support the source attribution by the inverse model. Although previous studies attributed measured benzene concentrations during the same time period to a cooling tower unit at the industrial complex, this study found that some of the flare units in the facility were also associated with the elevated benzene concentrations. The emissions of some of these flare units were found to be greater than reported in emission inventories, by up to two orders of magnitude.

Guven, B.; Olaguer, E. P.; Herndon, S. C.; Kolb, C. E.; Cuclis, A.

2012-12-01

77

Influence of benzene emission from motorcycle on Bangkok air quality  

Science.gov (United States)

This study investigated the influence of benzene concentration from motorcycle exhaust emissions on ambient air quality in Bangkok Metropolitan Region (BMR). Measurement of benzene concentration in exhaust emissions is performed on a standard test driving cycle through which each motorcycle to be tested is driven. The test result revealed that average benzene concentrations in exhaust emission for the test motorcycles ranged from 3.02 to 109.68 mg/m 3. The finding also indicated that two-stroke motorcycles emitted five times more benzene than that of four-stroke motorcycles. Four air monitoring sites were strategically established to determine the relationship between average benzene concentrations with different traffic configurations in each traffic zone of BMR during peak/non-peak hours, day/night times and weekday/weekend. The shape of the curve for benzene level usually shows two peaks corresponding to the morning and evening traffic rush or commuter rush hours. The finding shows that the mean concentrations for benzene in all monitoring stations in the ambient air for peak hours (07:00-09:00 and 16:00-18:00 h) ranged from 15.1 to 42.4 ?g/m 3. For non-peak hour (11:30-15:00 h), benzene levels were found in the range 16.3-30.9 ?g/m 3. It is observed that higher levels of benzene are found among roadside stations with slow moving traffic while lower levels are found among roadside stations with fast traffic movement. Additional factors such as temperature, wind speed, rainfall, etc. are also considered in this study to determine the relationship between traffic conditions and ambient benzene levels.

Leong, Shing Tet; Muttamara, S.; Laortanakul, Preecha

78

Influence of benzene emission from motorcycle on Bangkok air quality  

Energy Technology Data Exchange (ETDEWEB)

his study investigated the influence of benzene concentration from motorcycle exhaust emissions on ambient air quality in Bangkok Metropolitan Region (BMR). Measurement of benzene concentration in exhaust emissions is performed on a standard test driving cycle through which each motorcycle to be tested is driven. The test result revealed that average benzene concentrations in exhaust emission for the test motorcycles ranged from 3.02 to 109.68mg/m{sup 3}. The finding also indicated that two-stroke motorcycles emitted five times more benzene than that of four-stroke motorcycles. Four air monitoring sites were strategically established to determine the relationship between average benzene concentrations with different traffic configurations in each traffic zone of BMR during peak/non-peak hours, day/night times and weekday/weekend. The shape of the curve for benzene level usually shows two peaks corresponding to the morning and evening traffic rush or commuter rush hours. The finding shows that the mean concentrations for benzene in all monitoring stations in the ambient air for peak hours (07:00-09:00 and 16:00-18:00h) ranged from 15.1 to 42.4{mu}g/m{sup 3}. For non-peak hour (11:30-15:00h), benzene levels were found in the range 16.3-30.9{mu}g/m{sup 3}. It is observed that higher levels of benzene are found among roadside stations with slow moving traffic while lower levels are found among roadside stations with fast traffic movement. Additional factors such as temperature, wind speed, rainfall, etc. are also considered in this study to determine the relationship between traffic conditions and ambient benzene levels. (Author)

Leong, Shing Tet; Muttamara, S. [Asian Inst. of Technology, Pathumthani (Thailand). School of Environment, Resource and Development; Laortanakul, P.

2002-07-01

79

Different aggregation dynamics of benzene-water mixtures.  

Science.gov (United States)

All-atom molecular dynamics simulations for benzene-water mixtures are performed, aiming to explore the relationship between the microscopic structures and the thermodynamic properties, in particular, the transformation dynamics from the mutually soluble state to the phase-separated state. We find that the molecular aggregation of benzene in the water-rich mixture is distinctly different from that of water in the benzene-rich mixture. This aggregation difference is attributed to the different intermolecular interactions: the clustering of benzene molecules in the water-rich mixture is primarily driven by weak short-distance ?-? interactions; while the formation of water clusters in the benzene-rich solution is triggered by long-range dipole-dipole electrostatic interactions. Moreover, the molecular aggregations show double-scaled features: firstly assembling in a quasi-plane at a low concentration, then bulking in three dimensions with an increase in concentration. PMID:24949893

Fu, Cen-Feng; Tian, Shan Xi

2014-10-28

80

A MEMS-based Benzene Gas Sensor with a Self-heating WO3 Sensing Layer  

Directory of Open Access Journals (Sweden)

Full Text Available In the study, a MEMS-based benzene gas sensor is presented, consisting of a quartz substrate, a thin-film WO3 sensing layer, an integrated Pt micro-heater, and Pt interdigitated electrodes (IDEs. When benzene is present in the atmosphere, oxidation occurs on the heated WO3 sensing layer. This causes a change in the electrical conductivity of the WO3 film, and hence changes the resistance between the IDEs. The benzene concentration is then computed from the change in the measured resistance. A specific orientation of the WO3 layer is obtained by optimizing the sputtering process parameters. It is found that the sensitivity of the gas sensor is optimized at a working temperature of 300 °C. At the optimal working temperature, the experimental results show that the sensor has a high degree of sensitivity (1.0 K? ppm-1, a low detection limit (0.2 ppm and a rapid response time (35 s.

Lung-Ming Fu

2009-04-01

 
 
 
 
81

A MEMS-based Benzene Gas Sensor with a Self-heating WO(3) Sensing Layer.  

Science.gov (United States)

In the study, a MEMS-based benzene gas sensor is presented, consisting of a quartz substrate, a thin-film WO(3) sensing layer, an integrated Pt micro-heater, and Pt interdigitated electrodes (IDEs). When benzene is present in the atmosphere, oxidation occurs on the heated WO(3) sensing layer. This causes a change in the electrical conductivity of the WO(3) film, and hence changes the resistance between the IDEs. The benzene concentration is then computed from the change in the measured resistance. A specific orientation of the WO(3) layer is obtained by optimizing the sputtering process parameters. It is found that the sensitivity of the gas sensor is optimized at a working temperature of 300 °C. At the optimal working temperature, the experimental results show that the sensor has a high degree of sensitivity (1.0 K? ppm(-1)), a low detection limit (0.2 ppm) and a rapid response time (35 s). PMID:22574052

Ke, Ming-Tsun; Lee, Mu-Tsun; Lee, Chia-Yen; Fu, Lung-Ming

2009-01-01

82

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

83

Quantification of personal exposure concentrations to gasoline vehicle emissions in high-end exposure microenvironments: effects of fuel and season.  

Science.gov (United States)

Mobile-source air toxic (MSAT) levels increase in confining microenvironments (MEs) with numerous emission sources of vehicle exhaust or evaporative emissions or during high-load and cold-start conditions. Reformulated fuels are expected to reduce MSAT and ozone precursor emissions. This study, required under the Clean Air Act Section 211b, evaluated high-end exposures in cities using reformulated (methyl tertiary-butyl ether [MTBE] or ethanol [EtOH]) fuels and conventional gasoline blends. The study investigates 13 high-end MEs, sampling under enhanced exposure conditions expected to result in maximal fuel and exhaust component exposures to carbon monoxide (CO), carbon dioxide (CO2), BTEX (benzene, toluene, ethylbenzene, xylenes), MTBE, 1,3-butadiene (1,3-BD), EtOH,formaldehyde (HCHO), and acetaldehyde (CH3CHO). The authors found that day-to-day ME variations in high-end benzene, 1,3-BD, HCHO, and CO concentrations are substantial, but independent of gasoline composition and season, and related to the activity and emission rates of ME sources, which differ from day to day. PMID:23210226

Zielinska, B; Fujita, E; Ollison, W; Campbell, D; Sagebiel, J

2012-11-01

84

High nitrogen concentration in Fe-Cr-Ni alloys  

Science.gov (United States)

Increasing the nitrogen concentration in iron and iron alloys significantly improves their mechanical properties. A recent technique for melting in a hot-isostatic pressure furnace using nitrogen as the pressurizing gas has been developed by United States Bureau of Mines researchers for making massive nitrogen additions to iron (up to 1.6 wt pct nitrogen) and iron-chromium-nickel alloys (up to 6.6 weight percent nitrogen). The total nitrogen concentration measured at atmospheric pressure and room temperature was determined to be the equilibrium nitrogen concentration in the molten alloy. Statistical correlations were derived to explain the effects of melt pressure and alloy composition on the resulting nitrogen concentration. Nitrogen concentrations measured in solidified alloys made by high-pressure melting technique at lower pressures are consistent with previously published data. Computer generated phase diagrams for high nitrogen-chromium concentrations are also consistent with nitride microstructure observed after high-pressure melting. Extension of existing atmospheric nitrogen concentration data to higher pressure nitrogen concentrations shows Sievert’s Law (nitrogen concentration is proportional to the square root of the nitrogen melt pressure) to be valid for pure iron. However, substantial deviations from Sievert’s Law are observed for higher alloy compositions. Statistical fits of thermodynamic concentration data to the high-pressure melt nitrogen data require evaluating element concentration terms, interaction effect terms, pressure terms, and pressure-composition effect terms. Examination of the nitrogen concentration data suggests several methods of correlation.

Rawers, J. C.; Gokcen, N. A.; Pehlke, R. D.

1993-01-01

85

Benzene construction via organocatalytic formal [3+3] cycloaddition reaction.  

Science.gov (United States)

The benzene unit, in its substituted forms, is a most common scaffold in natural products, bioactive molecules and polymer materials. Nearly 80% of the 200 best selling small molecule drugs contain at least one benzene moiety. Not surprisingly, the synthesis of substituted benzenes receives constant attentions. At present, the dominant methods use pre-existing benzene framework to install substituents by using conventional functional group manipulations or transition metal-catalyzed carbon-hydrogen bond activations. These otherwise impressive approaches require multiple synthetic steps and are ineffective from both economic and environmental perspectives. Here we report an efficient method for the synthesis of substituted benzene molecules. Instead of relying on pre-existing aromatic rings, here we construct the benzene core through a carbene-catalyzed formal [3+3] reaction. Given the simplicity and high efficiency, we expect this strategy to be of wide use especially for large scale preparation of biomedicals and functional materials. PMID:25255058

Zhu, Tingshun; Zheng, Pengcheng; Mou, Chengli; Yang, Song; Song, Bao-An; Chi, Yonggui Robin

2014-01-01

86

Chlorinated benzenes cause concomitantly oxidative stress and induction of apoptotic markers in lung epithelial cells (A549) at nonacute toxic concentrations.  

Science.gov (United States)

In industrialized countries, people spend more time indoors and are therefore increasingly exposed to volatile organic compounds that are emitted at working places and from consumer products, paintings, and furniture, with chlorobenzene (CB) and 1,2-dichlorobenzene (DCB) being representatives of the halogenated arenes. To unravel the molecular effects of low concentrations typical for indoor and occupational exposure, we exposed human lung epithelial cells to CB and DCB and analyzed the effects on the proteome level by 2-D DIGE, where 860 protein spots were detected. A set of 25 and 30 proteins were found to be significantly altered due to exposure to environmentally relevant concentrations of 10(-2) g/m(3) of CB or 10(-3) g/m(3) of DCB (2.2 and 0.17 ppm), respectively. The most enriched pathways were cell death signaling, oxidative stress response, protein quality control, and metabolism. The involvement of oxidative stress was validated by ROS measurement. Among the regulated proteins, 28, for example, voltage-dependent anion-selective channel protein 2, PDCD6IP protein, heat shock protein beta-1, proliferating cell nuclear antigen, nucleophosmin, seryl-tRNA synthetase, prohibitin, and protein arginine N-methyltransferase 1, could be correlated with the molecular pathway of cell death signaling. Caspase 3 activation by cleavage was confirmed for both CB and DCB by immunoblotting. Treatment with CB or DCB also caused differential protein phosphorylation, for example, at the proteins HNRNP C1/C2, serine-threonine receptor associated protein, and transaldolase 1. Compared to previous results, where cells were exposed to styrene, for the chlorinated aromatic substances besides oxidative stress, apoptosis was found as the predominant cellular response mechanism. PMID:21171652

Mörbt, Nora; Tomm, Janina; Feltens, Ralph; Mögel, Iljana; Kalkhof, Stefan; Murugesan, Kalaimathi; Wirth, Henry; Vogt, Carsten; Binder, Hans; Lehmann, Irina; von Bergen, Martin

2011-02-01

87

Influence of ionization density on radiolysis of cyclohexane-benzene mixtures  

Science.gov (United States)

Cyclohexane-benzene mixtures were irradiated by 210Po-?-radiation (LET = 200 eV/nm) with the effective energy of 3 MeV and the results were compared with those obtained by 1.25 MeV ?-irradiation of 60Co (LET = 0.2 eV/nm). While during ?-irradiation—similarly to the data known from the literature—the G(c-C 6H 10) and the G((c-C 6H 11) 2) values were decreased even by a small amount of benzene, the yields of both products obtained by ?-irradiation were in the same range practically constant, and began to decrease only above the benzene concentration of 0.3 mol dm -3 (about 3 electron %). The "protection" in the case of ?-irradiation was interpreted by positive ion scavenging, S 1 excited cyclohexane molecule quenching and thermal H atoms scavenging. The low efficiency of all these three components of "protection" in ?-radiolysis is attributed principally to the very high concentration of intermediates in the track/core compared to the relatively low concentration of benzene. The conclusions were also supported by comparison with the data obtained in cyclohexane-iodine systems.

Földiák, G.; Roder, M.; Wojnárovits, L.

88

Sequence-Fenton Reaction for Decreasing Phenol Formation during Benzene Chemical Conversion in Aqueous Solutions  

Directory of Open Access Journals (Sweden)

Full Text Available Advanced oxidation processes such as Fenton reagent generates highly reactive hydroxyl free radicals to oxidize various compounds in the water and wastewater. The efficiency of different Fenton-related oxidative processes such as Fenton, solar-Fenton, UV-Fenton and Fenton reactions in different batch reactors was examined using benzene as pollutant in aqueous solutions. A batch study was conducted to optimize parameters like pH, hydrogen peroxide concentration, temperature, reaction time and ferrous ion concentration governing the Fenton process. The concentrations of produced phenol were measured at the end of the reactions. The role of sequence reaction was tested for decreasing phenol formation during benzene conversion. At optimum conditions, different Fenton-related processes were compared for the degradation of benzene. Increased degradation efficiency was observed in photo-Fenton processes as compared to conventional Fenton process. The formation of phenol in Fenton reaction depended on reaction time, sequence in reaction, purity of hydrogen peroxide and other compounds such as alcohols that contributed into the reaction. In the Fenton process, carboxylic acids like acetic acid and oxalic acid were formed as the end products during the complete degradation of benzene. With the increase in mono-valence, two-valence ions and hardness, Fenton's efficiency decreased, respectively. Sequence Fenton reaction produced less phenol and its end products had smaller COD as compared to conventional Fenton process.

SB Mortazavi, A Sabzali, A Rezaee

2005-04-01

89

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

1994-11-01

90

Peripheral blood effects in benzene-exposed workers.  

Science.gov (United States)

The hematotoxic effects of benzene exposure may be important in the occurrence of subsequent health effects. We sought to provide further information on peripheral blood effects by studying 928 workers in five factories in and around Shanghai, China exposed to a wide range of benzene concentrations. Specifically, we sought to investigate which blood indices are more strongly related to benzene exposure and which concentration levels of benzene result in peripheral blood changes. Lifestyle habits and demographic information was obtained via questionnaire, and potentially important genetic influences were determined by assessing single nucleotide polymorphisms in four genes (NQO1, MPO, CYP2E1, GSTT1). Weekly benzene exposure estimated from individual monitoring results ranged from 0.07 to 872 mg/m(3) with a median value of 7.4 mg/m(3). Twelve peripheral blood indices were examined. Stronger effects on peripheral blood were seen for red cell indices such as anemia and macrocytosis, albeit at higher (>10 ppm) exposure levels. The most sensitive parameters to benzene appeared to be neutrophils and the mean platelet volume (MPV), where effects were seen for benzene air concentrations of 7.8-8.2 ppm. Toluene exposure is a potential confounder for some peripheral blood effects, pointing to the need to scrutinize levels of both compounds in the occupational environment. PMID:20034484

Robert Schnatter, A; Kerzic, Patrick J; Zhou, Yimei; Chen, Min; Nicolich, Mark J; Lavelle, Karlene; Armstrong, Thomas W; Bird, Michael G; Lin, Lv; Fu, Hua; Irons, Richard D

2010-03-19

91

Thermodynamic properties of benzene under shock conditions.  

Science.gov (United States)

We present in this paper a thermodynamic analysis of benzene properties under shock conditions as given by molecular dynamics (MD) simulations. Reactive MD simulations of benzene predict a decomposition threshold corresponding to the flection point on the experimental Hugoniot curve. A polymerlike carbonated structure is observed for pressures above this threshold, but the calculated Hugoniot curve is in disagreement with the experimental one at high pressure. On the contrary, a system consisting of a diamond cluster in hydrogen gas leads to a correct prediction of the pressure on the Hugoniot curves. The central question is then linked to the kinetics of the transition between the polymerlike structure and the diamond cluster. PMID:18554024

Maillet, Jean-Bernard; Pineau, Nicolas

2008-06-14

92

Air pollution monitoring in Como urban areas. Benzene; Analisi dell'inquinamento di benzene a Como mediante un modello di regressione lineare multipla  

Energy Technology Data Exchange (ETDEWEB)

This work presents the results of a physical - statistical analysis of concentrations of benzene, measured in the Como Center station from 1996 to 1999. The analysis, conducted by means of the development, by steps, of a multifactorial linear regression model, permitted to find an annual trend of benzene, independently from the influence of meteorological variables. It has been seen a decrease of concentrations of benzene, from 1997 to 1999, that may be correlate to a decrease of tenor of benzene in the petrol. At the same time, the results of the model permit to understand the role and the relative weight of different climatic factors on the concentrations of benzene. It has been investigated the presence of daily, weekly and seasonal trend, too. [Italian] In questo lavoro si discutono i risultati di un'analisi fisico-statistico delle concentrazioni di benzene, misurate nella stazione di Como Centro dal 1996 al 1999. L'analisi, condotta mediante lo sviluppo, a step successivi, di un modello di regressione lineare multipla, ha permesso di individuare il trend annuale del benzene, depurato dall'influenza delle variabili meteorologiche. Si e' osservata una diminuzione delle concentrazioni di benzene dal 1997 al 1999, correlabile tra l'altro, alla diminuzione del tenore di benzene nelle benzine. Contemporaneamente, il modello selezionato ha permesso di individuare il ruolo ed il peso relativo dei diversi fattori climatici sulle concentrazioni di benzene. E' stata altresi' investigata la presenza di trend giornalieri, settimanali e stagionali.

Raffaele, L.; Lanzani, G.; Lanzoni, M. (comp.)

2001-11-01

93

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)

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.

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

1993-08-01

94

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

95

Factors impeding enzymatic wheat gluten hydrolysis at high solid concentrations.  

Science.gov (United States)

Enzymatic wheat gluten hydrolysis at high solid concentrations is advantageous from an environmental and economic point of view. However, increased wheat gluten concentrations result in a concentration effect with a decreased hydrolysis rate at constant enzyme-to-substrate ratios and a decreased maximum attainable degree of hydrolysis (DH%). We here identified the underlying factors causing the concentration effect. Wheat gluten was hydrolyzed at solid concentrations from 4.4% to 70%. The decreased hydrolysis rate was present at all solid concentrations and at any time of the reaction. Mass transfer limitations, enzyme inhibition and water activity were shown to not cause this hydrolysis rate limitation up to 50% solids. However, the hydrolysis rate limitation can be, at least partly, explained by a second-order enzyme inactivation process. Furthermore, mass transfer impeded the hydrolysis above 60% solids. Addition of enzyme after 24 h at high solid concentrations scarcely increased the DH%, suggesting that the maximum attainable DH% decreases at high solid concentrations. Reduced enzyme activities caused by low water activities can explain this DH% limitation. Finally, a possible influence of the plastein reaction on the DH% limitation is discussed. PMID:24474643

Hardt, N A; Janssen, A E M; Boom, R M; van der Goot, A J

2014-07-01

96

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

International Nuclear Information System (INIS)

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

97

Applications of nonimaging optics for very high solar concentrations  

Energy Technology Data Exchange (ETDEWEB)

Using the principles and techniques of nonimaging optics, solar concentrations that approach the theoretical maximum can be achieved. This has applications in solar energy collection wherever concentration is desired. In this paper, we survey recent progress in attaining and using high and ultrahigh solar fluxes. We review a number of potential applications for highly concentrated solar energy and the current status of the associated technology. By making possible new and unique applications for intense solar flux, these techniques have opened a whole new frontier for research and development of potentially economic uses of solar energy.

O`Gallagher, J.; Winston, R.

1997-12-31

98

Benzene vapor recovery and processing  

International Nuclear Information System (INIS)

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

99

Microalgae Tolerance to High Concentrations of Carbon Dioxide: A Review  

Directory of Open Access Journals (Sweden)

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.

Fadhil M. Salih

2011-07-01

100

Nonlinear diffusion in Acetone-Benzene Solution  

CERN Document Server

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.

Obukhovsky, Vjacheslav V

2010-01-01

 
 
 
 
101

Hemoglobin concentration of high-altitude Tibetans and Bolivian Aymara.  

Science.gov (United States)

Elevated hemoglobin concentrations have been reported for high-altitude sojourners and Andean high-altitude natives since early in the 20th century. Thus, reports that have appeared since the 1970s describing relatively low hemoglobin concentration among Tibetan high-altitude natives were unexpected. These suggested a hypothesis of population differences in hematological response to high-altitude hypoxia. A case of quantitatively different responses to one environmental stress would offer an opportunity to study the broad evolutionary question of the origin of adaptations. However, many factors may confound population comparisons. The present study was designed to test the null hypothesis of no difference in mean hemoglobin concentration of Tibetan and Aymara native residents at 3,800-4,065 meters by using healthy samples that were screened for iron deficiency, abnormal hemoglobins, and thalassemias, recruited and assessed using the same techniques. The hypothesis was rejected, because Tibetan males had a significantly lower mean hemoglobin concentration of 15.6 gm/dl compared with 19.2 gm/dl for Aymara males, and Tibetan females had a mean hemoglobin concentration of 14.2 gm/dl compared with 17.8 gm/dl for Aymara females. The Tibetan hemoglobin distribution closely resembled that from a comparable, sea-level sample from the United States, whereas the Aymara distribution was shifted toward 3-4 gm/dl higher values. Genetic factors accounted for a very high proportion of the phenotypic variance in hemoglobin concentration in both samples (0.86 in the Tibetan sample and 0.87 in the Aymara sample). The presence of significant genetic variance means that there is the potential for natural selection and genetic adaptation of hemoglobin concentration in Tibetan and Aymara high-altitude populations. PMID:9696153

Beall, C M; Brittenham, G M; Strohl, K P; Blangero, J; Williams-Blangero, S; Goldstein, M C; Decker, M J; Vargas, E; Villena, M; Soria, R; Alarcon, A M; Gonzales, C

1998-07-01

102

High efficiency photovoltaic roof tiles with static concentrators  

Energy Technology Data Exchange (ETDEWEB)

The use of static concentrators provides a level of concentration sufficient for significant cost reductions, without any of the problems of high concentration systems. There is no need for expensive tracking, most of the diffuse light is collected and passive cooling can be used for the cells. Following the construction of prototypes that confirm computer ray tracing predictions a structure has been designed for the manufacture of a 1 kW roof top array in association with the state power authority. Two manufacturing techniques for the array and potential commercial production are described. The pilot line at the University of New South Wales has commenced production of bifacial buried contact solar cells for the project. These cells provide the necessary high efficiency and low cost. Measurements have been made on the amount of dust likely to be present on a typical module, the effect on total internal reflection and thus the concentrator performance.

Bowden, S.; Wenham, S.R.; Dickinson, M.R.; Green, M.A. [Univ. of New South Wales, Sydney, New South Wales (Australia). Centre for Photovoltaic Devices and Systems

1994-12-31

103

Agitation leach experiment of fine ore and high grade concentrate  

International Nuclear Information System (INIS)

Lab experiment and field pilot test were conducted on a slurry from the ore crushing and classification process prior to heap leaching and on a high grade concentrate through ore separation. 96% of uranium extraction can be reached for the slurry ore applying acid leaching. 99% of uranium can be extracted for the concentrate by acid leaching, with the acid consumption being quite high as considerable carbonate associated with the concentrate. While alkaline leaching was applied to the concentrate, only 70% of uranium extraction was approached though the recovery could be enhanced significantly with the temperature increasing. Liquid/solid separation of the leached slurry is feasible through filtration using filter press, with the treatment capacity up to 155 kg/(m2·d) and the washing efficiency over 99%. (authors)

104

Radon Measurements in Buildings with High Radon Concentrations  

International Nuclear Information System (INIS)

Regarding radiation protection regulations in Slovenia measurements of natural radiation in public institutions have to be done by accredited laboratory to determine those with elevated radon concentrations. Ministry of Health started measurements of radon concentrations in schools and kindergartens twenty years ago. Almost all kindergartens and schools were included in monitoring. In kindergartens and schools with very high radon concentrations measurements were repeated and remediate if needed. Monitoring is continuing and in last five years 330 measurements of radon concentrations in public buildings by track each detectors were done. Radon concentrations in thirty five kindergartens and schools and twelve other public institutions were higher than proposed by regulations, 400 Bq/m3 for schools and kindergartens and 1000 Bq/m3 for other institutions. For those institutions special monitoring was carried out. We did thirty five measurements by electronic devices in the period of one week to determine radon and radon progeny concentrations. In case of high radon concentration in rooms also radon concentrations in cracks and water or electricity installations in the basement were measured. In special cases radon concentration in soil near building was measured. After measurements dose assessment was done and remediation actions proposed. Concerning results of radon concentration measurements we can conclude, (i) karst area and central southern part of Slovenia with limestone, marl and conglomerate as a main geological structure represent a strong radon source, (ii) old buildings with cracks in the floor make a great possibility to radon entering the rooms, and finally (iii) remediation actions are urgent in almost all old schools and kindergartens on the area presented. (author)

105

Sequence-Fenton Reaction for Decreasing Phenol Formation during Benzene Chemical Conversion in Aqueous Solutions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Advanced oxidation processes such as Fenton reagent generates highly reactive hydroxyl free radicals to oxidize various compounds in the water and wastewater. The efficiency of different Fenton-related oxidative processes such as Fenton, solar-Fenton, UV-Fenton and Fenton reactions in different batch reactors was examined using benzene as pollutant in aqueous solutions. A batch study was conducted to optimize parameters like pH, hydrogen peroxide concentration, temperature, reaction time and ...

Sb Mortazavi, A. Sabzali

2005-01-01

106

Hematotoxicity and carcinogenicity of benzene  

Energy Technology Data Exchange (ETDEWEB)

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.

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

1989-07-01

107

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)

108

Anaerobic degradation of benzene by marine sulfate-reducing bacteria  

Science.gov (United States)

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.

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

2010-05-01

109

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

DEFF Research Database (Denmark)

[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.

andersen, susanne; Pedersen, Leif Toudal

2007-01-01

110

High shear treatment of concentrates and drying conditions influence the solubility of milk protein concentrate powders.  

Science.gov (United States)

The solubility of milk protein concentrate (MPC) powders was influenced by the method used for preparing the concentrate, drying conditions, and the type of dryer used. Increasing total solids of the ultrafiltered concentrates (23% total solids, TS) by diafiltration to 25% TS or evaporation to 31% TS decreased the solubility of MPC powders (80-83% protein, w/w dry basis), with ultrafiltration followed by evaporation to higher total solids having the greater detrimental effect on solubility. High shear treatment (homogenisation at 350/100 bar, microfluidisation at 800 bar or ultrasonication at 24 kHz, 600 watts) of ultrafiltered and diafiltered milk protein concentrates prior to spray drying increased the nitrogen solubility of MPC powders (82% protein, w/w dry basis). Of the treatments applied, microfluidisation was the most effective for increasing nitrogen solubility of MPC powders after manufacture and during storage. Manufacture of MPC powders (91% protein, w/w dry basis) prepared on two different pilot-scale dryers (single stage or two stage) from milk protein concentrates (20% TS) resulted in powders with different nitrogen solubility and an altered response to the effects of microfluidisation. Microfluidisation (400, 800 and 1200 bar) of the concentrate prior to drying resulted in increased long term solubility of MPC powders that were prepared on a single stage dryer but not those produced on a two stage spray dryer. This work demonstrates that microfluidisation can be used as a physical intervention for improving MPC powder solubility. Interactions between the method of preparation and treatment of concentrate prior to drying, the drying conditions and dryer type all influence MPC solubility characteristics. PMID:22998771

Augustin, Mary Ann; Sanguansri, Peerasak; Williams, Roderick; Andrews, Helen

2012-11-01

111

[Metabolism features of bacteria resistant to high concentrations of chromate].  

Science.gov (United States)

Twenty strains of bacteria resistant to high concentrations of chromate were isolated from different ecological niches. They were able to reduce chromate to compounds of trivalent chromium--nonsoluble chromium hydroxide or soluble crystalline hydrates of trivalent chromium. The growth features of these microorganisms on media containing chromate at high concentrations (up to 20.0 g/l) are described. Besides chromate bacteria can reduce vanadate to compounds of V(4+) and Mo(6+) to Mo(5+). The best reduction takes place on the media where MPB. glucose or ethanol serves as the source of carbon. The growth and reduction of anion-in-study did not occur on organic acids. It was shown that tungstate, chlorate or perchlorate were not toxic for the studied bacteria up to concentrations of 10.0 g/l, however were not reduced by these microorganisms. The most active strains belong to genera Pseudomonas, Oerskovia, Bacillus, Micrococcus. PMID:23720958

Smirnova, G F; Podgorski?, V S

2013-01-01

112

Improved Dispersion of Carbon Nanotubes in Polymers at High Concentrations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The polymer nanocomposite used in this work comprises elastomer poly(dimethylsiloxane) (PDMS) as a polymer matrix and multi-walled carbon nanotubes (MWCNTs) as a conductive nanofiller. To achieve uniform distribution of carbon nanotubes within the polymer, an optimized dispersion process was developed, featuring a strong organic solvent—chloroform, which dissolved PDMS base polymer easily and allowed high quality dispersion of MWCNTs. At concentrations as high as 9 wt.%, MWCNTs were...

Chao-Xuan Liu; Jin-Woo Choi

2012-01-01

113

Benzene contamination at a metal plating facility  

Science.gov (United States)

A metal plating facility in central Kentucky was required to complete a RCRA Facility Investigation to address a number of Solid Waste Management Units at the site. Twenty monitoring wells were installed at the facility. Ground water from the wells was sampled for total and dissolved metals, polychlorinated biphenyls, acid extractable compounds, base neutral compounds, and volatile organic compounds. Unexpectedly, relatively large concentrations of benzene, up to 120 ?g/l, were detected in samples from some of the wells, including wells that should have been hydraulically upgradient from the facility. As a result of the detection of benzene, the facility completed an investigation to identify the source. A nearby facility had completed a gasoline underground storage tank (UST) closure at about the time of the installation of the 20 wells. Reportedly the UST had small holes when removed. Three potential pathways of migration (a ditch, sanitary sewer, and a sink hole) from the nearby facility to the metal-plating facility and residual soils with very large concentrations of benzene, toluene, ethylbenzene, and xylenes have been identified.

Memon, B. A.; Burston, M. R.

2005-08-01

114

Viscosity behavior of high-concentration protein mixtures.  

Science.gov (United States)

Highly concentrated protein solutions are becoming increasingly commonplace within the biopharmaceutical industry as more products are developed that feature high doses of drug intended for subcutaneous administration. An as-yet undeveloped subclass of these products feature multiple proteins coformulated together in high-concentration protein mixtures. Previous work has illustrated that the viscosity of aqueous solutions of various proteins at high concentrations can be remarkably different across otherwise similar molecules. This work characterizes the viscosity behavior of mixtures of such proteins, primarily monoclonal antibodies, and shows that a simple mixing rule first proposed by Arrhenius predicts the viscosity of an arbitrary mixture. This approach is shown to successfully calculate the viscosity of mixtures of proteins ranging up to 250 mg/mL total protein concentration and approximately 1700 cP at different ionic strengths and with accuracy errors of less than 10%. Only information about the viscosity of the isolated protein components of the mixture is required for the calculations. PMID:22170353

Galush, William J; Le, Lan N; Moore, Jamie M R

2012-03-01

115

Beryllium-10 concentrations in water samples of high northern latitudes  

Energy Technology Data Exchange (ETDEWEB)

{sup 10}Be concentrations in the water column of high northern latitudes were not available so far. We present different {sup 10}Be profiles from the Norwegian-Greenland Sea, the Arctic Ocean, and the Laptev Sea. (author) 3 fig., 3 refs.

Strobl, C.; Eisenhauer, A.; Schulz, V.; Baumann, S.; Mangini, A. [Heidelberger Akademie der Wissenschaften, Heildelberg (Germany); Kubik, P.W. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

1997-09-01

116

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

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

2013-01-01

117

The use of biomonitoring data in exposure and human health risk assessment: benzene case study  

Science.gov (United States)

A framework of “Common Criteria” (i.e. a series of questions) has been developed to inform the use and evaluation of biomonitoring data in the context of human exposure and risk assessment. The data-rich chemical benzene was selected for use in a case study to assess whether refinement of the Common Criteria framework was necessary, and to gain additional perspective on approaches for integrating biomonitoring data into a risk-based context. The available data for benzene satisfied most of the Common Criteria and allowed for a risk-based evaluation of the benzene biomonitoring data. In general, biomarker (blood benzene, urinary benzene and urinary S-phenylmercapturic acid) central tendency (i.e. mean, median and geometric mean) concentrations for non-smokers are at or below the predicted blood or urine concentrations that would correspond to exposure at the US Environmental Protection Agency reference concentration (30?µg/m3), but greater than blood or urine concentrations relating to the air concentration at the 1?×?10?5 excess cancer risk (2.9?µg/m3). Smokers clearly have higher levels of benzene exposure, and biomarker levels of benzene for non-smokers are generally consistent with ambient air monitoring results. While some biomarkers of benzene are specific indicators of exposure, the interpretation of benzene biomonitoring levels in a health-risk context are complicated by issues associated with short half-lives and gaps in knowledge regarding the relationship between the biomarkers and subsequent toxic effects. PMID:23346981

Angerer, Juergen; Boogaard, Peter J.; Hughes, Michael F.; O'Lone, Raegan B.; Robison, Steven H.; Robert Schnatter, A.

2013-01-01

118

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

119

Benzene adsorption on basal planes of boron nitride; comparison with the benzene-graphite system  

Science.gov (United States)

A set of adsorption isotherms of benzene on boron nitride have been determined between 198 and 268 K. Just as in the case of the benzene-graphite system, the isotherms do not present the shape of the stepped isotherm. The benzene layer appears more mobile with a weaker adsorption energy on boron nitride than on graphite. The monolayer defined at the point B presents an important negative thermal expansion coefficient. It is proposed that the first layer might be unstable at high coverage and transform into clusters leaving some bare surface of boron nitride. Thus the observed isotherms might be considered as a combination of type I and III according to the Brunauer classification.

Delachaume, J. C.; Coulon, M.; Bonnetain, L.

1983-10-01

120

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)

 
 
 
 
121

Manufacture of concentrated, lipid-based oxygen microbubble emulsions by high shear homogenization and serial concentration.  

Science.gov (United States)

Gas-filled microbubbles have been developed as ultrasound contrast and drug delivery agents. Microbubbles can be produced by processing surfactants using sonication, mechanical agitation, microfluidic devices, or homogenization. Recently, lipid-based oxygen microbubbles (LOMs) have been designed to deliver oxygen intravenously during medical emergencies, reversing life-threatening hypoxemia, and preventing subsequent organ injury, cardiac arrest, and death. We present methods for scaled-up production of highly oxygenated microbubbles using a closed-loop high-shear homogenizer. The process can produce 2 L of concentrated LOMs (90% by volume) in 90 min. Resulting bubbles have a mean diameter of ~2 ?m, and a rheologic profile consistent with that of blood when diluted to 60 volume %. This technique produces LOMs in high capacity and with high oxygen purity, suggesting that this technique may be useful for translational research labs. PMID:24894333

Thomson, Lindsay M; Polizzotti, Brian D; McGowan, Frances X; Kheir, John N

2014-01-01

122

Behavior of particulate matter during high concentration episodes in Seoul.  

Science.gov (United States)

The behavior of particulate matter (PM) during high-concentration episodes was investigated using monitoring data from Guui station, a comprehensive air monitoring station in Seoul, Korea, from January 2008 to March 2010. Five non-Asian dust (ND) episodes and two Asian dust (AD) episodes of high PM concentrations were selected for the study. During the ND episode, primary air pollutants accumulated due to low wind speeds, and PM2.5 increased along with most other air pollutants. Particles larger than PM2.5 were also high since these particles were generated by vehicular traffic rather than wind erosion. During strong AD episodes, PM10-2.5 primarily increased and gaseous primary air pollutants decreased under high wind speeds. However, even during the AD episode, PM2.5 and gaseous primary air pollutants increased when the effects of AD were weak and wind speeds were low. This study corroborates that accumulation of air pollutants due to a drop in surface wind speed plays an important role in short-term high-concentration occurrences. However, low wind speeds could not be directly linked to local emissions because a significant portion of accumulated air pollutants resulted from long-range transport. PMID:24464082

Choi, Soon-Ho; Ghim, Young Sung; Chang, Young-Soo; Jung, Kweon

2014-05-01

123

Compound Precipitation in High-Concentration DMSO Solutions.  

Science.gov (United States)

Screening compounds precipitate out of high-concentration DMSO solutions and cause issues in the liquid-handling equipment used to process the samples as well as false-positives and false-negatives in the biological data. This report examines the extent of the precipitation issue, correlation with physico-chemical properties of compounds, and measured concentrations. Possible ways to allow recovery of the precipitated solids are also described. This study also investigated whether particulates were present from the time of initial solubilization in DMSO or whether precipitation occurs during freeze-thaw cycling. PMID:24980595

Popa-Burke, Ioana; Russell, John

2014-10-01

124

Chitosan macroporous foams obtained in highly concentrated emulsions as templates.  

Science.gov (United States)

Emulsion templating is an effective route for the preparation of macroporous polymer foams, with well-defined pore structures. This kind of material is usually obtained by polymerization or crosslinking in the external phase of highly concentrated emulsions. The present article describes the synthesis of macroporous foams based on a cationic polymer, chitosan, crosslinked with genipin, a natural crosslinker. The phase behavior was used to study the influence of chitosan on surfactant self-aggregation. Hexagonal and lamellar liquid crystalline structures could be obtained in the presence of chitosan, and polymer did not greatly influence the geometric lattice parameters of these self-aggregates. O/W highly concentrated emulsions were obtained in the presence of chitosan in the continuous phase, which allowed reducing both droplet size and polydispersity. The emulsions were stable during the time required for crosslinking, obtaining macroporous foams with high pore volume and degree of crosslinking. PMID:24011788

Miras, Jonathan; Vílchez, Susana; Solans, Conxita; Esquena, Jordi

2013-11-15

125

Review of silicon solar cells for high concentrations  

Science.gov (United States)

The factors that limit the performance of high concentration silicon solar cells are reviewed. The design of a conventional high concentration cell is discussed, together with the present state of the art. Unconventional cell designs that have been proposed to overcome the limitations of the conventional design are reviewed and compared. The current status of unconventional cells is reviewed. Among the unconventional cells discussed are the interdigitated back-contact cell, the double-sided cell, the polka dot cell, and the V-groove cell. It is noted that all the designs for unconventional cells require long diffusion lengths for high efficiency operation, even though the demands in this respect are less for those cells with the optical path longer than the diffusion path.

Schwartz, R. J.

1982-06-01

126

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)

127

Acute toxicity of high concentrations of carbon dioxide in rats.  

Science.gov (United States)

Subterranean storage of carbon dioxide (CO2) has been proposed to diminish atmospheric increases of this greenhouse gas. To contribute to risk assessment of accidental release associated with handling, transport and storage, rats were exposed to high concentrations (targets 40, 43 and 50 volume %) of CO2. The oxygen concentrations dropped as a result, but were not supplemented. For each concentration, pairs of animals were exposed for different exposure durations to derive an exposure concentration-duration relation in which mortality is described as a function of C(n)×t (probit relation). A very high "n" value for the probit function could be derived from the data obtained at 40% and 43% CO2, which indicates that for exposure durations longer than 30 min the LC50 decreases hardly with increasing exposure duration. Below 30 min the LC50 seemed to increase with decreasing exposure durations. The variability in the data of 43% and 50% CO2, however, did not allow to derive a meaningful value of "n". PMID:24713210

Muijser, H; van Triel, J J; Duistermaat, E; Bos, P M J

2014-07-01

128

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

Science.gov (United States)

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. PMID:25362307

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

2014-10-28

129

Mitigation of high 222 Rn concentrations in potable water  

International Nuclear Information System (INIS)

Potable water is recommended to have less than 300 p Ci/L (11.1 Bq/L) of 222Rn because of its potential carcinogenic effects. Some well water may have exceedingly high 222Rn concentrations and must be mitigated to be potable. This study was carried out on well water artificially enriched with 222Rn simulating well water naturally high in 222Rn concentration. This water was then subjected to different mitigation treatments. This included aeration treatment, adding granulated activated carbon and a heating treatment. The mitigating effect of varying the main parameters of each treatment was investigated. It is concluded that aeration treatment is the preferred mitigation method because of is efficiency and least environmental impact

130

Dynamics of highly concentrated protein solutions around the denaturing transition  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Using both quasi-elastic and fixed-window neutron spectroscopy, we study the dynamics of highly concentrated aqueous protein solutions of bovine serum albumin around the denaturing transition. For the temperature range 280 K < T < 370 K, the total mean-squared displacement ?u 2? is recorded. Below and above the denaturing, we observe that ?u 2? increases monotonically with T, but at the denaturing transition it decreases strongly...

Hennig, M.; Roosen-runge, F.; Zhang, F.; Zorn, S.; Skoda, Mwa; Jacobs, Rmj; Seydel, T.; Schreiber, F.

2012-01-01

131

Studying Interactions by Molecular Dynamics Simulations at High Concentration  

Science.gov (United States)

Molecular dynamics simulations have been used to study molecular encounters and recognition. In recent works, simulations using high concentration of interacting molecules have been performed. In this paper, we consider the practical problems for setting up the simulation and to analyse the results of the simulation. The simulation of beta 2-microglobulin association and the simulation of the binding of hydrogen peroxide by glutathione peroxidase are provided as examples. PMID:22500085

Fogolari, Federico; Corazza, Alessandra; Toppo, Stefano; Tosatto, Silvio C. E.; Viglino, Paolo; Ursini, Fulvio; Esposito, Gennaro

2012-01-01

132

Highly concentrated emulsions. Physicochemical principles of the preparation and stability  

International Nuclear Information System (INIS)

Theoretical and experimental studies on highly concentrated emulsions are critically analysed. The views on the relationship between the stability of surfactant-stabilised emulsions and the properties of microemulsion phases formed in surfactant-water-oil ternary systems are considered. The empirical criteria and rules that can be used to predict the type and stability of emulsions are presented. The physicochemical factors determining the rupture stability of emulsion films are discussed.

133

Living with high concentrations of urea: They can!  

Directory of Open Access Journals (Sweden)

Full Text Available 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 osmolarity, mainly main-tained by urea retention, is a challenge to volume homeostasis when fish move from seawater to water with a low salinity, since the high water permeability of branchial epithelium would cause a net flux of water into the animal. Since the renal regulation of urea retention in habitat with different salinities is crucial for the osmotic homeostasis of these species, the regulation of the activity and/or the expression of urea trans porters in renal tubules will be also discussed. In addition attention will be paid on the urea– methylamine system involved in maintaining the stability and functioning of many proteins since it is known that the high urea concentration found in marine elasmobranch fish, similar only to that found in mammalian kidney, has a destabilizing effect on many macromolecules and inhibits functions such as ligand binding.

Caterina Faggio

2012-01-01

134

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

135

Major sources of benzene exposure.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Wallace, L. A.

1989-01-01

136

Secondary organic aerosol formation from m-xylene, toluene, and benzene  

Science.gov (United States)

Secondary organic aerosol (SOA) formation from the photooxidation of m-xylene, toluene, and benzene is investigated in the Caltech environmental chambers. Experiments are performed under two limiting NOx conditions; under high-NOx conditions the peroxy radicals (RO2) react only with NO, while under low-NOx conditions they react only with HO2. For all three aromatics studied (m-xylene, toluene, and benzene), the SOA yields (defined as the ratio of the mass of organic aerosol formed to the mass of parent hydrocarbon reacted) under low-NOx conditions substantially exceed those under high-NOx conditions, suggesting the importance of peroxy radical chemistry in SOA formation. Under low-NOx conditions, the SOA yields for m-xylene, toluene, and benzene are constant (36%, 30%, and 37%, respectively), indicating that the SOA formed is effectively nonvolatile under the range of Mo(>10 ?g m-3) studied. Under high-NOx conditions, aerosol growth occurs essentially immediately, even when NO concentration is high. The SOA yield curves exhibit behavior similar to that observed by Odum et al. (1996, 1997a, b), although the values are somewhat higher than in the earlier study. The yields measured under high-NOx conditions are higher than previous measurements, suggesting a "rate effect" in SOA formation, in which SOA yields are higher when the oxidation rate is faster. Experiments carried out in the presence of acidic seed aerosol reveal no change of SOA yields from the aromatics as compared with those using neutral seed aerosol.

Ng, N. L.; Kroll, J. H.; Chan, A. W. H.; Chhabra, P. S.; Flagan, R. C.; Seinfeld, J. H.

2007-07-01

137

Partial hydrogenation of benzene to cyclohexene  

Science.gov (United States)

We (Asahi Chemical Industy Co., Ltd.) have developed a technology for a highly selective partial hydrogenation of benzene to cyclohexene and succeeded in the commercialization of a new production process for producing cyclohexanol from benzene through cyclohexene. The process has been considered to be difficult for a long time in the industry. Several innovative technologies made the partial hydrogenation reaction possible. A catalyst that consists of specific metallic ruthenium particles exhibited excellent high selectivity of cyclohexene. The catalyst was obtained by reducing a ruthenium compound which contains a zinc compound. The use of a zinc of strong acid as a co-catalyst exhibited a remarkable effect to enhance selectivity. Dispersing agents of metal oxides were found to extend the life of the metallic ruthenium catalyst and some dispersing agents had the effect of enhancing the selectivity in the partial hydrogenation reaction. One of the remarkable features of the reaction was the reaction field. This comprises four phases: vapor (hydrogen), oil, aqueous and solid (ruthenium catalyst). The catalyst was used in the aqueous phase, and the reactants (benzene and hydrogen) were dissolved in the aqueous phase where the reaction proceeded. Therefore the products and reactants transfer between four phases through dissolution, diffusion and extraction, rendering quick transfer was a very important factor in enhancing reaction selectivity. The catalyst system and the reaction field described above made the selectivity for cyclohexene very high, and a yield of 60% for cyclohexene was obtained.

Nagahara, H.; Ono, M.; Konishi, M.; Fukuoka, Y.

1997-11-01

138

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)

139

Research on biological effects induced by ?-irradiation combined with benzene, toluene and carbon monoxide inhalation  

International Nuclear Information System (INIS)

Objective: To explore the patterns of biological effects induced by ?-rays irradiation combined with simultaneous inhalation benzene, toluene or carbon monoxide and to analyze their antagonistic,additive or synergistic interaction. Methods: Ninety healthy male rabbits were equally divided into 9 groups. Eight of which were assigned to be test groups according to four-factor-two-dose-level orthogonal layout {L8(27) } program and the other one was the control group. The two dose-levels of these four agents were: the ?-irradiation doses were 0.0075 Gy/d and 0.0375 Gy/d, and the two concentrations of benzene, toluene and carbon monoxide were 40 +-15 and 162 +- 33 mg/m3, 90 +- 30 and 407 +- 68 mg/m3, 93 +- 4 and 278 +- 8 mg/m3, respectively. The animals were exposed to ?-irradiation combined with benzene,toluene or CO vapour 2 h a day and 5 days a week for successive 8 weeks. Variance analysis and comparison between test groups were made for analyzing the test data. Results: (1) It was showed that ?-irradiation, benzene and toluene could all induce chromosome aberrations, SCEs and micronuclei of lymphocytes and chromosome aberrations of bone marrow cells; but no effect could be seen in CO alone treated group. (2) The ratios (?) of biological effects jointly induced by the four agents and the sum of those induced separately by them were 2.16, 1.58, 2.07, 2.67, 1.25 and 1.18 for dicentric + ring,acentric, aberrationdicentric + ring,acentric, aberration cells, total aberration, micronuclei and micronucleus cells, respectively,and it was as high as 5.97 for aberrant sperms.The ratios showed that the interactions were synergistic(?>1). However,interactions between ?-rays and benzene was antagonistic for acentric of lymphocytes. (3) The four agents could all obviously cause decrease of weight index of testis, ?-rays,toluene and CO could all markedly reduce the number of sperms and increase the ratio of aberrant sperms. Conclusion: ?-irradiation combined with benzene, toluene and CO inhalation can lead to significant interactions which are mainly synergistic,while CO can cause obvious effects on sex gland when it is combined with ?-rays, benzene and toluene

140

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

 
 
 
 
141

Disposal of high-concentration hydrazine solutions by chemical decomposition  

International Nuclear Information System (INIS)

Corrosion prevention and oxygen removal require hydrazine to be used in the various circuits of power plants at concentrations established bench-scale and corroborated by operational experience. However, these hydrazine contents are too high for any discharge of waste water from system scavenging at inspections and other necessary tests or from desludging for improving water quality. Hydrazine concentrations must be reduced to comply with the legal provisions covering the discharge of effluents into tributories. A process version for hydrazine decomposition was tested in the Grohnde nuclear power plant. Hydrazine is decomposed in an up-to-date filter plant with a palladium-doped ion exchanger with H2O2 added. (orig./RB)

142

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)

143

Benzene bioremediation using cow dung microflora in two phase partitioning bioreactor  

International Nuclear Information System (INIS)

Bioremediation of benzene has been carried out using cow dung microflora in a bioreactor. The bioremediation of benzene under the influence of cow dung microflora was found to be 100% and 67.5%, at initial concentrations of 100 mg/l and 250 mg/l within 72 h and 168 h respectively; where as at higher concentration (500 mg/l), benzene was found to be inhibitory. Hence the two phase partitioning bioreactor (TPPB) has been designed and developed to carryout biodegradation at higher concentration. In TPPB 5000 mg/l benzene was biodegraded up to 50.17% over a period of 168 h. Further the Pseudomonas putida MHF 7109 was isolated from cow dung microflora as potential benzene degrader and its ability to degrade benzene at various concentrations was evaluated. The data indicates 100%, 81% and 65% degradation at the concentrations of 50 mg/l, 100 mg/l, 250 mg/l within the time period of 24 h, 96 h and 168 h respectively. The GC-MS data also shows the presence of catechol and 2-hydroxymuconic semialdehyde, which confirms the established pathway of benzene biodegradation. The present research proves the potential of cow dung microflora as a source of biomass for benzene biodegradation in TPPB.

144

Benzene bioremediation using cow dung microflora in two phase partitioning bioreactor  

Energy Technology Data Exchange (ETDEWEB)

Bioremediation of benzene has been carried out using cow dung microflora in a bioreactor. The bioremediation of benzene under the influence of cow dung microflora was found to be 100% and 67.5%, at initial concentrations of 100 mg/l and 250 mg/l within 72 h and 168 h respectively; where as at higher concentration (500 mg/l), benzene was found to be inhibitory. Hence the two phase partitioning bioreactor (TPPB) has been designed and developed to carryout biodegradation at higher concentration. In TPPB 5000 mg/l benzene was biodegraded up to 50.17% over a period of 168 h. Further the Pseudomonas putida MHF 7109 was isolated from cow dung microflora as potential benzene degrader and its ability to degrade benzene at various concentrations was evaluated. The data indicates 100%, 81% and 65% degradation at the concentrations of 50 mg/l, 100 mg/l, 250 mg/l within the time period of 24 h, 96 h and 168 h respectively. The GC-MS data also shows the presence of catechol and 2-hydroxymuconic semialdehyde, which confirms the established pathway of benzene biodegradation. The present research proves the potential of cow dung microflora as a source of biomass for benzene biodegradation in TPPB.

Singh, Dipty [Environmental Biotechnology Laboratory, Department of Life Sciences, University of Mumbai, Vidyanagari Campus, Santacruz (E), Mumbai-400 098 (India); Fulekar, M.H., E-mail: mhfulekar@yahoo.com [Environmental Biotechnology Laboratory, Department of Life Sciences, University of Mumbai, Vidyanagari Campus, Santacruz (E), Mumbai-400 098 (India)

2010-03-15

145

Gradual adaptive changes of a protein facing high salt concentrations.  

Science.gov (United States)

Several experimental techniques were applied to unravel fine molecular details of protein adaptation to high salinity. We compared four homologous enzymes, which suggested a new halo-adaptive state in the process of molecular adaptation to high-salt conditions. Together with comparative functional studies, the structure of malate dehydrogenase from the eubacterium Salinibacter ruber shows that the enzyme shares characteristics of a halo-adapted archaea-bacterial enzyme and of non-halo-adapted enzymes from other eubacterial species. The S. ruber enzyme is active at the high physiological concentrations of KCl but, unlike typical halo-adapted enzymes, remains folded and active at low salt concentrations. Structural aspects of the protein, including acidic residues at the surface, solvent-exposed hydrophobic surface, and buried hydrophobic surface, place it between the typical halo-adapted and non-halo-adapted proteins. The enzyme lacks inter-subunit ion-binding sites often seen in halo-adapted enzymes. These observations permit us to suggest an evolutionary pathway that is highlighted by subtle trade-offs to achieve an optimal compromise among solubility, stability, and catalytic activity. PMID:20888835

Coquelle, Nicolas; Talon, Romain; Juers, Douglas H; Girard, Eric; Kahn, Richard; Madern, Dominique

2010-12-01

146

Recovery of uranium from solutions containing high concentration of fluoride  

International Nuclear Information System (INIS)

Various methods involving ion exchange and solvent extraction are described for the recovery of macro amounts as well as traces of uranium containing high concentrations of fluoride ions. Of these, the ion exchange procedure involving the use of the carbonate form of a strong base anion exchanger, viz. Dowex-1 from aqueous carbonate media and subsequent elution with ammonium nitrate is described in detail. This method gave quantitative recovery of uranium with the final product (U3O8) containing approximately 100 ppm sodium and approximately 2 ppm fluoride. (author)

147

Experimental Study on High-Concentration Gradient Transversal Dispersion  

Science.gov (United States)

Previous experimental studies on vertical stable displacement report that when the residing fluid, e.g., freshwater, is displaced by a solution with a higher density, e.g., saltwater a decrease in the longitudinal dispersion coefficient is observed. This decrease of the coefficient is more pronounce when the density differences increase. As classical Fick's Law is not able to describe such phenomena, new theories have been proposed to incorporate the effects of density variations. Furthermore, results from aforementioned studies satisfactorily validated the alternative theories. Here, we study the effects of high-concentration gradients on the transverse dispersion coefficient. Two-dimensional laboratory-scale tank experiments are conducted under stable flow conditions with fresh water introduced in the upper half of the flow model and saltwater (for different salt mass fractions) introduced in the bottom half of the tank. The two fluids flow parallel and adjacent to each other in the porous medium, mixing through transverse dispersion. Using electrical conductivity meters, steady-state salt concentration profiles are measured at different transects along the flow tank. From these concentration profiles transverse dispersion coefficients are estimated. The experimental system used allows to systematically investigate the effects of mean flow rate, density differences between fluids and type of porous medium on the coefficient. Results from the experiments will be presented, and future work will be indicated.

Gutierrez, M.; Kleingeld, P.; Schotting, R. J.

2006-12-01

148

Observation of high concentrations of radon in certain houses  

International Nuclear Information System (INIS)

High concentrations of radon were observed in houses in the Argonne area in Illinois in the course of exhalation studies on the residents. The high levels were not related to radioactivity in building materials or to uranium tailings in the foundations. Various possible sources of the radon were investigated and it was finally concluded that it was emanating from the soil in the unpaved crawl space under the houses. It was calculated that radon was leaving the soil surface at a rate of about 26nCihr-1m-2. It is concluded that the average exposure of man to radon daughters in houses in the USA may be higher than has hitherto been thought, and the need for a comprehensive survey is suggested. (author)

149

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

150

High manganese concentrations in rocks at Gale crater, Mars  

Science.gov (United States)

surface of Mars has long been considered a relatively oxidizing environment, an idea supported by the abundance of ferric iron phases observed there. However, compared to iron, manganese is sensitive only to high redox potential oxidants, and when concentrated in rocks, it provides a more specific redox indicator of aqueous environments. Observations from the ChemCam instrument on the Curiosity rover indicate abundances of manganese in and on some rock targets that are 1-2 orders of magnitude higher than previously observed on Mars, suggesting the presence of an as-yet unidentified manganese-rich phase. These results show that the Martian surface has at some point in time hosted much more highly oxidizing conditions than has previously been recognized.

Lanza, Nina L.; Fischer, Woodward W.; Wiens, Roger C.; Grotzinger, John; Ollila, Ann M.; Cousin, Agnes; Anderson, Ryan B.; Clark, Benton C.; Gellert, Ralf; Mangold, Nicolas; Maurice, Sylvestre; Le Mouélic, Stéphane; Nachon, Marion; Schmidt, Mariek; Berger, Jeffrey; Clegg, Samuel M.; Forni, Olivier; Hardgrove, Craig; Melikechi, Noureddine; Newsom, Horton E.; Sautter, Violaine

2014-08-01

151

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

152

Air ion concentrations under overhead high-voltage transmission lines  

Science.gov (United States)

This paper reports net concentrations of small ions (NCSI) monitored at 41 sites under overhead high voltage ac power lines in and around an urban environment. The net ionic polarity under power lines was of both signs but mostly positive and NCSI varied widely from 0 to 3300 cm -3. Concomitant measurements of the vertical dc electric field at the ground confirmed the presence of a net positive charge above. Approximately, 19% of the sites exhibited relatively high NCSI exceeding 1000 cm -3. The mean value of all the sites was 776 cm -3. Statistically, the mean for the transmission voltage (220-330 kV) line sites was significantly higher than that for the sub-transmission voltage (110-132 kV) line sites with means of 905 and 501 cm -3, respectively. These values were compared with the mean urban outdoor concentration well away from the lines which was about 400 cm -3 and of negative polarity. Overall, NCSI at approximately 76% of the power line sites exceeded the absolute mean urban outdoor value. The dc electric fields under the power lines showed a statistically significant relationship to the measured NCSI, although there was considerable scatter to indicate that electric field measurements do not necessarily reflect NCSI in the air at ground level.

Jayaratne, E. R.; J-Fatokun, F. O.; Morawska, L.

153

Do high concentrations of microcystin prevent Daphnia control of phytoplankton?  

Science.gov (United States)

Toxin-producing cyanobacteria have frequently been hypothesized to limit the ability of herbivorous zooplankton (such as Daphnia) to control phytoplankton biomass by inhibiting feeding, and in extreme cases, causing zooplankton mortality. Using limnocorral experiments in hyper-eutrophic ponds located in Alabama and Michigan (U.S.A.), we tested the hypothesis that high levels of cyanobacteria and microcystin, a class of hepatotoxins produced by several cyanobacterial genera, prevent Daphnia from strongly reducing phytoplankton abundance. At the start of the first experiment (Michigan), phytoplankton communities were dominated by toxic Microcystis and Anabaena (?96% of total phytoplankton biomass), and concentrations of microcystin were ?3 ?g L?¹. Two weeks after adding Daphnia pulicaria from a nearby eutrophic lake, microcystin levels increased to ?6.5 ?g L?¹, yet Daphnia populations increased exponentially (r = 0.24 day?¹). By the third week, Daphnia had suppressed phytoplankton biomass by ?74% relative to the no Daphnia controls and maintained reduced phytoplankton biomass until the conclusion of the five-week experiment. In the second experiment (Alabama), microcystin concentrations were greater than 100 ?g L?¹, yet a mixture of three D. pulicaria clones from eutrophic lakes in southern MI increased and again reduced phytoplankton biomass, in this case by over 80%. The ability of Daphnia to increase in abundance and suppress phytoplankton biomass, despite high initial levels of cyanobacteria and microcystin, indicates that the latter does not prevent strong control of phytoplankton biomass by Daphnia genotypes that are adapted to environments with abundant cyanobacteria and associated cyanotoxins. PMID:23395484

Chislock, Michael F; Sarnelle, Orlando; Jernigan, Lauren M; Wilson, Alan E

2013-04-15

154

First DIAMEX partitioning using genuine high active concentrate  

International Nuclear Information System (INIS)

The efficiency of Minor Actinides (MA) recovery in the DIAMEX process has already been demonstrated using High Active Raffinate (HAR). The next step aims at the partitioning of MA from High Active Concentrate (HAC) as feed, in view of an industrial application. The volume reduction reduces the size of the installation and thereby the costs of the process. In this work, MA recovery by DIAMEX partitioning using genuine HAC has for the first time been demonstrated. The experiment was successfully carried out in a 18-stage centrifugal extractor battery, installed in the hot cell facilities at ITU, using 1 MN,N'-Dimethyl N,N'-Di-Octyl-Hexyl-Malonamide (DMDOHEMA) as extractant. In order to produce a representative HAC, a concentration-denitration process was applied to a genuine HAR solution produced by small scale Purex reprocessing of a MOX fuel solution. In the DIAMEX process up to 5 extraction stages were sufficient to achieve feed decontamination factors above 20000 for minor actinides. Co-extraction of molybdenum, zirconium and palladium were prevented using oxalic acid and HEDTA scrubbing. The back extraction proved to be very efficient, yielding in 4 stages recoveries for Am and Cm in the Ln/An effluent above 99.7 and 99.9% respectively, which can be improved by process optimisation. This work is a major contribution in the field of partitioning and an important step towards the industrial implementation of MA partitioning. (author)

155

Phenolic metabolites of benzene inhibited the erythroid differentiation of K562 cells.  

Science.gov (United States)

Benzene is a common occupational hazard and a ubiquitous environmental pollutant. Benzene exposure at the levels even below 1ppm still showed hematotoxicity. It is widely accepted that the metabolites of benzene play important roles in the benzene toxicity to the hematopoietic system, but little is known about the effects of benzene metabolites on erythropoiesis. In present study, erythroid progenitor-like K562 cells were used to determine the effects of phenolic metabolites of benzene, including phenol, hydroquinone and 1,2,4-benzenetriol, on the erythroid differentiation. After the treatment with these benzene metabolites at the concentrations with no obvious cytotoxicity, the hemin-induced hemoglobin synthesis in K562 cells decreased in a concentration- and time-dependent manner, and the expression of CD71 and GPA protein on the surface of K562 cells was also inhibited. The reverse transcription-PCR was used to determine the mRNA level of the erythroid related genes in the K562 cells that were treated with benzene metabolites. The hemin-induced expression of globin genes, including ?-, ?- and ?-globin genes, and the gene encoding the heme synthesis enzyme porphobilinogen deaminase was inhibited by benzene metabolites. When the K562 cells were pretreated with benzene metabolites, the hemin-induced expression of two transcription factor genes GATA-1 and NF-E2 was distinctly reduced, and the pre-treatment with benzene metabolites promoted the decrease of the mRNA level of transcription factor gene GATA-2 by hemin. These results indicated that benzene metabolites inhibited the hemin-induced erythroid differentiation through affecting the transcription of the erythroid related genes. PMID:21414390

Wu, Xiao-Rong; Xue, Ming; Li, Xiao-Fei; Wang, Yan; Wang, Jie; Han, Qing-Ling; Yi, Zong-Chun

2011-06-24

156

Source identification of high glyme concentrations in the Oder River.  

Science.gov (United States)

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

Stepien, D K; Püttmann, W

2014-05-01

157

Remediation of groundwater contaminated with MTBE and benzene: the potential of vertical-flow soil filter systems.  

Science.gov (United States)

Field investigations on the treatment of MTBE and benzene from contaminated groundwater in pilot or full-scale constructed wetlands are lacking hugely. The aim of this study was to develop a biological treatment technology that can be operated in an economic, reliable and robust mode over a long period of time. Two pilot-scale vertical-flow soil filter eco-technologies, a roughing filter (RF) and a polishing filter (PF) with plants (willows), were operated independently in a single-stage configuration and coupled together in a multi-stage (RF+PF) configuration to investigate the MTBE and benzene removal performances. Both filters were loaded with groundwater from a refinery site contaminated with MTBE and benzene as the main contaminants, with a mean concentration of 2970±816 and 13,966±1998 ?g L(-1), respectively. Four different hydraulic loading rates (HLRs) with a stepwise increment of 60, 120, 240 and 480 L m(-2) d(-1) were applied over a period of 388 days in the single-stage operation. At the highest HLR of 480 L m(-2) d(-1), the mean concentrations of MTBE and benzene were found to be 550±133 and 65±123 ?g L(-1) in the effluent of the RF. In the effluent of the PF system, respective mean MTBE and benzene concentrations of 49±77 and 0.5±0.2 ?g L(-1) were obtained, which were well below the relevant MTBE and benzene limit values of 200 and 1 ?g L(-1) for drinking water quality. But a dynamic fluctuation in the effluent MTBE concentration showed a lack of stability in regards to the increase in the measured values by nearly 10%, which were higher than the limit value. Therefore, both (RF+PF) filters were combined in a multi-stage configuration and the combined system proved to be more stable and effective with a highly efficient reduction of the MTBE and benzene concentrations in the effluent. Nearly 70% of MTBE and 98% of benzene were eliminated from the influent groundwater by the first vertical filter (RF) and the remaining amount was almost completely diminished (?100% reduction) after passing through the second filter (PF), with a mean MTBE and benzene concentration of 5±10 and 0.6±0.2 ?g L(-1) in the final effluent. The emission rate of volatile organic compounds mass into the air from the systems was less than 1% of the inflow mass loading rate. The results obtained in this study not only demonstrate the feasibility of vertical-flow soil filter systems for treating groundwater contaminated with MTBE and benzene, but can also be considered a major step forward towards their application under full-scale conditions for commercial purposes in the oil and gas industries. PMID:21794890

van Afferden, Manfred; Rahman, Khaja Z; Mosig, Peter; De Biase, Cecilia; Thullner, Martin; Oswald, Sascha E; Müller, Roland A

2011-10-15

158

Characterization of blood donors with high haemoglobin concentration  

DEFF Research Database (Denmark)

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.

Magnussen, K; Hasselbalch, H C

2013-01-01

159

The impact of reduction in the benzene limit value in gasoline on airborne benzene, toluene and xylenes levels.  

Science.gov (United States)

Background benzene, toluene, xylenes (BTX) average concentrations have been measured over the urban agglomeration of Toulouse, France, during both springtime and summer periods of 1999 and 2001. The benzene average amount over the two Toulouse campaigns in 1999 is equal to 2.2 microg/m(3), very close to the French air quality standard and well under the average value of 5 microg/m(3) recommended by European Economic Community countries, recognising that those regulations are given for a whole year. BTX pollution over Toulouse has, in particular, been produced by motor vehicle exhaust gases. For the study conducted during the same periods of 2001, benzene concentrations were within the French quality value in the whole area. This is because the benzene limit value contained in gasoline went from 5% to 1% since 2000 January 1. It will be important to measure benzene over annual periods in order to know its exact values over such a period and to observe its potential seasonal variations. PMID:15504504

Simon, V; Baer, M; Torres, L; Olivier, S; Meybeck, M; Della Massa, J P

2004-12-01

160

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

International Nuclear Information System (INIS)

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.

 
 
 
 
161

High Nitrate Concentrations in Vacuolate, Autotrophic Marine Beggiatoa spp.  

Science.gov (United States)

Massive accumulations of very large Beggiatoa spp. are found at a Monterey Canyon cold seep and at Guaymas Basin hydrothermal vents. Both environments are characterized by high sediment concentrations of soluble sulfide and low levels of dissolved oxygen in surrounding waters. These filamentous, sulfur-oxidizing bacteria accumulate nitrate intracellularly at concentrations of 130 to 160 mM, 3,000- to 4,000-fold higher than ambient levels. Average filament widths range from 24 to 122 (mu)m, and individual cells of all widths possess a central vacuole. These findings plus recent parallel discoveries for Thioploca spp. (H. Fossing, V. A. Gallardo, B. B. Jorgensen, M. Huttel, L. P. Nielsen, H. Schulz, D. E. Canfield, S. Forster, R. N. Glud, J. K. Gundersen, J. Kuver, N. B. Ramsing, A. Teske, B. Thamdrup, and O. Ulloa, Nature (London) 374:713-715, 1995) suggest that nitrate accumulation may be a universal property of vacuolate, filamentous sulfur bacteria. Ribulose bisphosphate carboxylase-oxygenase and 2-oxoglutarate dehydrogenase activities in the Beggiatoa sp. from Monterey Canyon suggest in situ autotrophic growth of these bacteria. Nitrate reductase activity is much higher in the Monterey Beggiatoa sp. than in narrow, laboratory-grown strains of Beggiatoa spp., and the activity is found primarily in the membrane fraction, suggesting that the vacuolate Beggiatoa sp. can reduce nitrate coupled to electron flow through an electron transport system. Nitrate-concentrating and respiration potentials of these chemolithoautotrophs suggest that the Beggiatoa spp. described here are an important link between the sulfur, nitrogen, and carbon cycles at the Monterey Canyon seeps and the Guaymas Basin hydrothermal vents where they are found. PMID:16535282

McHatton, S C; Barry, J P; Jannasch, H W; Nelson, D C

1996-03-01

162

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)

163

Dish-based high concentration PV system with Köhler optics.  

Science.gov (United States)

We present work at the Steward Observatory Solar Lab on a high concentration photovoltaic system in which sunlight focused by a single large paraboloidal mirror powers many small triple-junction cells. The optical system is of the XRX-Köhler type, comprising the primary reflector (X) and a ball lens (R) at the focus that reimages the primary reflector onto an array of small reflectors (X) that apportion the light to the cells. We present a design methodology that provides generous tolerance to mis-pointing, uniform illumination across individual cells, minimal optical loss and even distribution between cells, for efficient series connection. An operational prototype has been constructed with a 3.3m x 3.3m square primary reflector of 2m focal length powering 36 actively cooled triple-junction cells at 1200x concentration (geometric). The measured end-to-end system conversion efficiency is 28%, including the parasitic loss of the active cooling system. Efficiency ~32% is projected for the next system. PMID:24922230

Coughenour, Blake M; Stalcup, Thomas; Wheelwright, Brian; Geary, Andrew; Hammer, Kimberly; Angel, Roger

2014-03-10

164

Removal of benzene and methyl ethyl ketone vapor: comparison of hypercrosslinked polymeric adsorbent with activated carbon.  

Science.gov (United States)

A novel hypercrosslinked polymeric adsorbent (HY-1) with high surface area and specific bimodal pore size distribution in the regions of micropore (0.5-2.0 nm) and meso-macropore (30-70 nm) was prepared. Adsorption properties of benzene and methyl ethyl ketone (MEK) vapors onto HY-1 were investigated and compared with a commercial microporous activated carbon (m-GAC). The equilibrium adsorption data showed that the adsorption capacities of benzene and MEK on HY-1 were larger than those of m-GAC at the higher relative pressure. The Dubinin-Radushkevich (D-R) equation was found to fit the experimental data well. The isosteric enthalpy of adsorption for benzene and MEK were calculated. The m-GAC exhibited much higher values of ?H(st) for the VOCs than HY-1 at the whole loading studied, which can lead to significant temperature rises during the adsorption step. The results of dynamic experiments revealed that HY-1 had a good dynamic adsorption capacity with a longer breakthrough time and shorter length of mass transfer zone due to its specific bimodal property. Therefore, HY-1 will be a particularly efficient and competitive adsorbent for VOCs recovery, especially at medium-high concentrations. PMID:22204838

Long, Chao; Li, Ying; Yu, Weihua; Li, Aimin

2012-02-15

165

Microbial life at high salt concentrations: phylogenetic and metabolic diversity  

Directory of Open Access Journals (Sweden)

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.

Oren Aharon

2008-04-01

166

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)

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.

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

167

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)

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.

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

2014-10-01

168

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...following legend: DANGER BENZENE CANCER HAZARD FLAMMABLE—NO SMOKING AUTHORIZED...legend: DANGER CONTAINS BENZENE CANCER HAZARD (2) Material safety data sheets...tubes should be capped with the supplied plastic caps immediately after sampling....

2010-07-01

169

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...employee's use of protective clothing or equipment and respirators... DANGER BENZENE CANCER HAZARD FLAMMABLE...personal protective clothing and equipment are required...wear the protective clothing and equipment. VII...Benzene I. Physical and Chemical Data A....

2010-07-01

170

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

... (1 ) Past work exposure to benzene...outside of the current work situation. ...signs which may be related to benzene exposure...relating to blood disorders: (B) A complete...employee's medical and work history related to exposure to...

2010-07-01

171

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...Systemic absorption may cause depression of the hematopoietic...liquid benzene immediately causes pulmonary edema and...contact with benzene may cause erythema. Repeated...followed by a period of depression, drowsiness, or...

2010-07-01

172

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...physical signs relating to blood disorders: (B) A complete blood...Systemic absorption may cause depression of the hematopoietic system...liquid benzene immediately causes pulmonary edema and hemorrhage...Exposure to benzene may cause an early rise in serum...

2010-07-01

173

Materials Balance for Benzene: Level II.  

Science.gov (United States)

A Level II materials balance was performed on benzene. Data are reported for benzene production from petroleum by four processes (catalytic reformation, toluene dealkylation, toluene disproportionation, and isolation from pyrolysis gasoline) for productio...

F. Montecalvo, R. Burger, R. L. Hall

1980-01-01

174

Modelling acceptance of sunlight in high and low photovoltaic concentration  

Science.gov (United States)

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.

Leutz, Ralf

2014-09-01

175

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)

176

Anaerobic Benzene Oxidation by Geobacter Species  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

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

2012-01-01

177

Role of delocalization in benzene  

Energy Technology Data Exchange (ETDEWEB)

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.

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

178

Design and development of a high-concentration and high-efficiency photovoltaic concentrator using a curved Fresnel lens  

Energy Technology Data Exchange (ETDEWEB)

Thermo Electron has designed a high concentration photovoltaic module that uses a domed, point-focus Fresnel lens. Their design, design optimization process, and results from lens and receiver tests are described in this report. A complete module has not been fabricated and probably will not be fabricated in the future; however, Thermo Electron's optical design, analysis, and testing of both secondary optical units and domed Fresnel lenses have made a significant contribution to our project. Tooling errors prevented the lens from reaching its potential efficiency by the end of the contract, and resolution of these tooling problems is currently being attempted with a follow-on contract, No. 68-9463.

Scharlack, R.S.; Moffat, A.

1983-08-01

179

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...

180

Chemical Potential of Benzene Fluid from Monte Carlo Simulation with Anisotropic United Atom Model  

Directory of Open Access Journals (Sweden)

Full Text Available The profile of chemical potential of benzene fluid has been investigated using Anisotropic United Atom (AUA model. A Monte Carlo simulation in canonical ensemble was done to obtain the isotherm of benzene fluid, from which the excess part of chemical potential was calculated. A surge of potential energy is observed during the simulation at high temperature which is related to the gas-liquid phase transition. The isotherm profile indicates the tendency of benzene to condensate due to the strong attractive interaction. The results show that the chemical potential of benzene rapidly deviates from its ideal gas counterpart even at low density.

Mahfuzh Huda

2013-07-01

 
 
 
 
181

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

182

Benzene emission from the actual car fleet in relation to petrol composition in Denmark  

International Nuclear Information System (INIS)

The present study covers an investigation of the trends in air pollution levels of benzene in Danish cities and their relationship with the benzene content in petrol. Petrol samples from the two refineries in Denmark as well as sold petrol from some representative Danish petrol stations were analysed. The benzene content in Danish petrol was reduced from 3.5% for 95 octane prior to 1995 to approx. 2% in 1995 and further to 1% in 1998. Air quality measurements of aromatic VOC are available from two Danish cities; Copenhagen since 1994 and Odense since 1997. Measurements of benzene, CO and NOx from these two locations were analysed using the Operational Street Pollution Model (OSPM) and trends in the actual emissions of these pollutants were determined. It is shown that the decrease in both the concentration levels and in the emissions was significantly larger for benzene than for CO and NOx. The decreasing trends of NOx and CO could be explained by the increasing fraction of petrol-fuelled vehicles with three way catalysts (TWC). The much steeper decreasing trend for benzene can most likely be attributed to a combination of the effect of the increasing share of the TWC vehicles and a simultaneous reduction of benzene content in Danish petrol. The reduction of benzene concentrations and emissions is observed despite that the total amount of aromatics in petrol has increased slightly in the same period. (Author)

183

Benzene emission from the actual car fleet in relation to petrol composition in Denmark  

Science.gov (United States)

The present study covers an investigation of the trends in air pollution levels of benzene in Danish cities and their relationship with the benzene content in petrol. Petrol samples from the two refineries in Denmark as well as sold petrol from some representative Danish petrol stations were analysed. The benzene content in Danish petrol was reduced from 3.5% for 95 octane prior to 1995 to approx. 2% in 1995 and further to 1 % in 1998. Air quality measurements of aromatic VOC are available from two Danish cities; Copenhagen since 1994 and Odense since 1997. Measurements of benzene, CO and NO x from these two locations were analysed using the Operational Street Pollution Model (OSPM) and trends in the actual emissions of these pollutants were determined. It is shown that the decrease in both the concentration levels and in the emissions was significantly larger for benzene than for CO and NO x. The decreasing trends of NO x and CO could be explained by the increasing fraction of petrol-fuelled vehicles with three way catalysts (TWC). The much steeper decreasing trend for benzene can most likely be attributed to a combination of the effect of the increasing share of the TWC vehicles and a simultaneous reduction of benzene content in Danish petrol. The reduction of benzene concentrations and emissions is observed despite that the total amount of aromatics in petrol has increased slightly in the same period.

Palmgren, Finn; Hansen, Asger B.; Berkowicz, Ruwim; Skov, Henrik

184

Molecular dynamics simulations of shocked benzene  

International Nuclear Information System (INIS)

The behavior of benzene at high temperatures and pressures is studied using nonequilibrium molecular dynamics. The interatomic forces were generated using linear-scaling tight-binding electronic structure theory on systems containing 128 and 576 molecules. The shock Hugoniot, calculated directly from the simulations without predetermining the equation of state, is compared with experiment. Piston velocities of 4 km/s or greater result in a pressure-induced polymerization. This transition is consistent with the bend in the experimental measurements of shock versus piston velocity. (c) 2000 American Institute of Physics

185

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)

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

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

2014-04-25

186

Pumping power station ash as a high concentration slurry  

Energy Technology Data Exchange (ETDEWEB)

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.

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

187

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

Energy Technology Data Exchange (ETDEWEB)

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)

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

2011-10-15

188

Concentrator cost bound for high-efficiency photovoltaic power production  

Energy Technology Data Exchange (ETDEWEB)

An upper bound on the cost per unit aperture area of a solar concentrator is obtained which is completely model independent. The result relates the maximum cost of a concentrator system (if it is to be competitive with low efficiency, low cost solar cell arrays) to the efficiency of photocells comprising an array. (SPH)

Faiman, D.

1979-01-01

189

Aerosol formation and decomposition of dilute benzene derivatives by AC/DC corona discharge  

Energy Technology Data Exchange (ETDEWEB)

The most common treatment methods for removing volatile organic compounds (VOCs) include thermal decomposition, catalytic oxidation, carbon adsorption, destruction in non-thermal plasma (NTP) and condensation. Among these technologies, the use of NTP is gaining considerable attention, particularly AC/DC energized corona plasma systems because of their reliable operation, low cost and high efficiency. One of the ideal NTP based processes is to convert VOCs to environmentally sound compounds, such as water. However, since the plasma-initialed reactions are difficult to control, some undesirable products such as aerosols are often observed from VOC removal. The formation of aerosol must therefore be considered in structure-dependent VOC removal characteristics. This study examined the decomposition of three benzene derivatives by novel AC/DC corona discharge with a closed loop flow system in air. The experiments focused primarily on aerosol formation and the individual removal efficiency of benzene, toluene and styrene. The removal process of styrene, benzene and toluene were found to be different from each other because of their different reactivity with radicals. The generated radicals of styrene were efficiently used for the removal process, but the generated radicals of benzene and toluene were mainly quenched by bulk gases. The study showed that a large concentration of aerosols can be generated in humid air. The generated aerosols can be collected by electrostatic precipitation in the AC/DC energized plasma system. It was concluded that the chemical structure is one of most important factors that influence the removal process of VOCs for non-thermal plasma processing. 17 refs., 7 figs.

Zhang, X.; Chen, W.; Zhu, J.; Feng, W.; Yan, K. [Zhejiang Univ., Hangzhou (China). Industrial Ecology and Environment Research Inst.

2010-07-01

190

Bandgap Engineering in High-Efficiency Multijunction Concentrator Cells  

Energy Technology Data Exchange (ETDEWEB)

This paper discusses semiconductor device research paths under investigation with the aim of reaching the milestone efficiency of 40%. A cost analysis shows that achieving very high cell efficiencies is crucial for the realization of cost-effective photovoltaics, because of the strongly leveraging effect of efficiency on module packaging and balance-of systems costs. Lattice-matched (LM) GaInP/ GaInAs/ Ge 3-junction cells have achieved the highest independently confirmed efficiency at 175 suns, 25?C, of 37.3% under the standard AM1.5D, low-AOD terrestrial spectrum. Lattice-mismatched, or metamorphic (MM), materials offer still higher potential efficiencies, if the crystal quality can be maintained. Theoretical efficiencies well over 50% are possible for a MM GaInP/ 1.17-eV GaInAs/ Ge 3-junction cell limited by radiative recombination at 500 suns. The bandgap - open circuit voltage offset, (Eg/q) - Voc, is used as a valuable theoretical and experimental tool to characterize multijunction cells with subcell bandgaps ranging from 0.7 to 2.1 eV. Experimental results are presented for prototype 6-junction cells employing an active {approx}1.1-eV dilute nitride GaInNAs subcell, with active-area efficiency greater than 23% and over 5.3 V open-circuit voltage under the 1-sun AM0 space spectrum. Such cell designs have theoretical efficiencies under the terrestrial spectrum at 500 suns concentration exceeding 55% efficiency, even for lattice-matched designs.

King, R. R.; Sherif, R. A.; Kinsey, G. S.; Kurtz, S.; Fetzer, C. M.; Edmondson, K. M.; Law, D. C.; Cotal, H. L.; Krut, D. D.; Ermer, J. H.; Karam, N. H.

2005-08-01

191

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)

Full Text Available SciELO Public Health | Language: English Abstract in english 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.

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

2010-12-01

192

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)

Full Text Available SciELO Public Health | Language: English Abstract in english 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.

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

193

Muconic acid determinations in urine as a biological exposure index for workers occupationally exposed to benzene  

Energy Technology Data Exchange (ETDEWEB)

GC-MS analyses of the urine of 14 exposed and 8 unexposed workers showed a linear correlation between muconic acid level and time-weighted average concentration of benzene in ambient air. Workers exposed to benzene concentrations as low as 4.4 ppm over an 8 h shift showed urinary muconic acid levels significantly (p[lt]0.005) higher than those of controls.

Bechtold, W.E. (and others)

1991-11-01

194

High-density lipoprotein concentrations increase after stopping smoking.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Concentrations of plasma lipoproteins in 10 men who were habitual smokers were monitored for six weeks after they stopped smoking and related to changes in diet and body weight. The energy intake increased by 10% (p less than 0.05) owing to a higher consumption of carbohydrates and fat, and body weight increased by 2% (p less than 0.01). Plasma triglyceride, cholesterol, and low-density lipoprotein cholesterol concentrations did not change significantly. The most prominent finding was a rapid...

Math, M. V.

1982-01-01

195

Intermolecular interactions in solid benzene.  

Science.gov (United States)

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. PMID:16460192

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

2006-01-28

196

Adsorption of vapor-phase VOCs (benzene and toluene) on modified clays and its relation with surface properties  

Energy Technology Data Exchange (ETDEWEB)

A study was conducted to investigate the potential use of modified clays for the adsorption of volatile organic compounds (VOCs) present in air. These VOCs which include toluene and benzene, are among the main air pollutants that represent a human health risk at high concentrations, mostly in indoor environments. In this study, a Mexican bentonite was used to prepare 3 modified clays, notably an organoclay (OC-CPC) by intercalating cetylpyridinium chloride (CPC); an aluminum-pillared clay (Al-PILC); and an inorganic-organic clay (IOC-CPC) prepared from Al-PILC intercalating CPC. Their structures were differentiated by infrared and thermogravimetric analyses, and the interlayer distance was assessed through X-ray diffraction. Toluene and benzene adsorption on OC-CPC was higher than in IOC-CPC and Al-PILC. Natural clay showed no adsorption capacity for these compounds. Comparison of the gas chromatography retention times for non polar and low-polarity compounds (octyne and benzene) in columns packed with OC-CPC and a commercial non polar column (squalene) showed that the OC-CPC possessed a higher organophilic (non polar) nature than squalene. This explains the higher benzene and toluene adsorption capacity of the OC-CPC compared with the other modified clays. It was concluded that organoclays represent a potential alternative for the adsorption of volatile organic compounds such as benzene and toluene present in indoor environments. Since the OC-CPC is hydrophobic by nature, the relative humidity of water vapour in the environment would not affects its adsorption capacity. 27 refs., 5 tabs., 5 figs.

Lopez-Cortes, C.; Gallardo-Velazquez, T.; Arellano-Cardenas, S. [National School of Biological Sciences (Mexico). Biophysics Dept.; Osorio-Revilla, G. [National School of Biological Sciences (Mexico). Biochemical Engineering Dept.

2008-04-15

197

Removal of actinides from high level waste containing high concentration salt by DHDECMP  

International Nuclear Information System (INIS)

The results of the extraction of U(IV), Np(IV, V, VI), Pu(IV) and Am(III) from simulated high level waste containing high concentration salt by bidentate extractant dihexyl-N, N-diethyl-carbamylmethlenephosphonate (DHDECMP) in diethylbenzene (DEB) are summarized. Stripping of U, Np, Pu and Am from loaded organic phase was also studied. Multistage countercurrent cascade experiments (4 stages for extraction, 2 stages for scrubbing) were carried out with simulated waste containing high concentration salt and trace Am(III). The removal efficiency of Am is greater than 99.9%. Multistage countercurrent cascade experiments (6 stages for stripping) were also carried out with loaded organic phase from extraction experiments. The stripping efficiency of Am is greater than 99.9%. (17 refs., 4 figs., 4 tabs.)

198

ANALYSIS OF HIGH SULFATE CONCENTRATIONS IN GREATER NEW YORK CITY AIR  

Science.gov (United States)

The meteorological phenomena occurring during April 15 to 21, 1976, when high sulfate concentrations were measured in the New York City area, are summarized. Findings of earlier investigations of relationships between meteorological phenomena and high sulfate concentrations are c...

199

The obtaining a high-grade gadolinium concentrate  

International Nuclear Information System (INIS)

Gadolinium concentrates obtained by the fractional precipitation of lanthanon-potassium double chromates were separated by ion exchange with 0,4 M lactic acid solution in the presence of 0,1 M ammonium nitrate at pH of the medium 2,95-3,4. It was found out, that using the fractional precipitation of lanthanon-potassium double chromates (as the fast and cheap method that does not need special equipment) together with ion exchange separation with lactic acid solution as the eluent gave a highgrade gadolinium concentrate in a quick and economical way. (author)

200

[Studies of ozone formation potentials for benzene and ethylbenzene using a smog chamber and model simulation].  

Science.gov (United States)

Ozone formation potentials from irradiations of benzene-NO(x) and ethylbenzene-NO(x) systems under the conditions of different VOC/NO(x) ratios and RH were investigated using a characterized chamber and model simulation. The repeatability of the smog chamber experiment shows that for two sets of ethylbenzene-NO(x) irradiations with similar initial concentrations and reaction conditions, such as temperature, relative humidity and relative light intensity, the largest difference in O3 between two experiments is only 4% during the whole experimental run. On the basis of smog chamber experiments, ozone formation of photo-oxidation of benzene and ethylbenzene was simulated in terms of the master chemical mechanism (MCM). The peak ozone values for benzene and ethylbenzene simulated by MCM are higher than the chamber data, and the difference between the MCM-simulated results and chamber data increases with increasing RH. Under the conditions of sunlight irradiations, with benzene and ethylbenzene concentrations being in the range of (10-50) x 10(-9) and NO(x) concentrations in the range of (10-100) x 10(-9), the 6 h ozone contributions of benzene and ethylbenzene were obtained to be (3.1-33) x 10(-9) and (2.6-122) x 10(-9), whereas the peak O3 contributions of benzene and ethylbenzene were (3.5-54) x 10(-9) and (3.8-164) x 10(-9), respectively. The MCM-simulated maximum incremental reactivity (MIR) values for benzene and ethylbenzene were 0.25/C and 0.97/C (per carbon), respectively. The maximum ozone reactivity (MOR) values for these two species were obtained to be 0.73/C and 1.03/C, respectively. The MOR value of benzene from MCM is much higher than that obtained by carter from SAPRC, indicating that SAPRC may underestimate the ozone formation potential of benzene. PMID:24812939

Jia, Long; Xu, Yong-Fu

2014-02-01

 
 
 
 
201

[Detoxification of high concentrations of trinitrotoluene by bacteria].  

Science.gov (United States)

The ability of the strains-destructors of various aromatic compounds to utilize trinitrotoluene (TNT) up to concentration of 70 mg/1 was shown. An increase in the TNT concentration from 100 to 150 mg/1 did not inhibit its conversion rate by the Kocuria palustris RS32 strain. The Acinetobacter sp. VT 11 strain utilized TNT as a sole substrate for growth; 3,5-dinitro-4-methyl anilide acetate and 2,6-dinitro-4-aminotoluene were identified as intermediates of TNT degradation by active strains of Pseudomonas sp. VT-7W and Kocuria rosea RS51. At the same time, 4-methyl-3,5-dinitroformamide was discovered for the first time upon the TNT destruction by the bacteria strains of Rhodococcus opacus 1G and Rhodococcus sp. VT-7. The active bacterial strains achieved an 82-90% destruction of TNT when they were introduced into the soil. PMID:22567882

Solianikova, I P; Baskunov, B P; Baboshin, M A; Saralov, A I; Golovleva, L A

2012-01-01

202

Dimerization in Highly Concentrated Solutions of Phosphoimidazolide Activated Mononucleotides  

Science.gov (United States)

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.

Kanavarioti, Anastassia

1997-01-01

203

DNA damage by ribose: inhibition at high ribose concentrations.  

Science.gov (United States)

Nucleobases and DNA react non-enzymatically with sugars, and generate DNA-advanced glycation end products (DNA-AGEs). Incubation of plasmid pBr322 with ribose for 3-7 days caused the transformation of the supercoiled plasmid to the open circular and linear forms. Removal of sugar after an initial 24 h incubation resulted in marked enhancement in the transformation rate. Enhancement in transformation was also observed when bovine serum albumin (BSA) exposed to ribose for short durations was incubated with plasmid in absence of the sugar. The effect on DNA was attenuated when excess ribose remained in the incubation mixture of ribose and protein. The data suggested that an increase in ribose concentration in the vicinity of DNA could be damaging and the damage exacerbated, if sugar levels fell subsequently. Incubation of herring sperm DNA with ribose resulted in a concentration and time-dependent increase of N2-carboxyethyl-2'-deoxyguanosine (CEdGA,B). The concentration of CEdGA,B, however, did not increase further when ribose was removed from the reaction mixture. PMID:20653285

Waris, Sahar; Pischetsrieder, Monika; Saleemuddin, Mohammed

2010-06-01

204

Variability of benzene exposure among filling station attendants; Variabilita` dell`esposizione a benzene tra gli addetti all`erogazione di carburanti  

Energy Technology Data Exchange (ETDEWEB)

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.

Carere, A.; Iacovella, N.; Turrio Baldassarri, L. [Istituto Superiore di Sanita`, Rome (Italy). Lab. di Tossicologia Comparata ed Ecotossicologia; Fuselli, S.; Iavarone, I.; Lagorio, S.; Proietto, A.R. [Istituto Superiore di Sanita`, Rome (Italy). Lab. di Igiene Ambientale

1996-12-01

205

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

LENUS (Irish Health Repository)

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.

McNally, P

2012-02-01

206

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

Science.gov (United States)

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. PMID:21532584

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

207

Benzene exposure assessment for use of a mineral spirits-based degreaser.  

Science.gov (United States)

This study examines benzene emissions from the use of a metal parts washer ("degreaser") supplied with a mineral spirits solvent containing either 9 or 58 ppm benzene. Air samples were obtained during a one-hour session of relatively vigorous parts cleaning activity using a degreaser station equipped with wet brush and sprayer attachments and a compressed air hose. Two methods were utilized to assess airborne benzene levels: U.S. EPA TO-14 (summa stainless steel canister) and NIOSH 1501 (charcoal tube). Overall, both methods provided similar results, excepting detection limit differences. The first simulation was performed with recycled solvent (9 ppm benzene in solvent) showing average one-hour airborne benzene levels spiked recycled solvent (58 ppm benzene) showed airborne benzene levels averaging 500 ppbv measured over the 60-minute cleaning period in the worker's breathing zone and directly above the tank, while average concentrations 18 inches from the tank perimeter were 63 ppbv. The data indicate that average and peak exposures to airborne benzene were roughly proportional to the solvent benzene content, although the brief peak exposures exhibited greater variance probably related to aerosol generation associated with the use of the brush and/or spraying attachment. Under this selected upper bound exposure simulation, we found that cleaning parts using a recycled mineral spirits-based solvent in an open warehouse setting did not result in exposures in excess of the current occupational exposure limit of 0.5 ppm averaged over 8 hours for solvent benzene content between 9 and 58 ppm. PMID:12959887

Fedoruk, Marion J; Bronstein, Rod; Kerger, Brent D

2003-10-01

208

Benzene inhalation by parts washers: new estimates based on measures of occupational exposure to solvent coaromatics.  

Science.gov (United States)

Questions persist regarding assessment of workers' exposures to products containing low levels of benzene, such as mineral spirit solvent (MSS). This study summarizes previously unpublished data for parts-washing activities, and evaluates potential daily and lifetime cumulative benzene exposures incurred by workers who used historical and current formulations of a recycled mineral spirits solvent in manual parts washers. Measured benzene concentrations in historical samples from parts-washing operations were frequently below analytical detection limits. To better assess benzene exposure among these workers, air-to-solvent concentration ratios measured for toluene, ethylbenzene, and xylenes (TEX) were used to predict those for benzene based on a statistical model, conditional on physical-chemical theory supported by new thermodynamic calculations of TEX and benzene activity coefficients in a modeled MSS-type solvent. Using probabilistic methods, the distributions of benzene concentrations were then combined with distributions of other exposure parameters to estimate eight-hour time-weighted average (TWA) exposure concentration distributions and corresponding daily respiratory dose distributions for workers using these solvents in parts washers. The estimated 50th (95th) percentile of the daily respiratory dose and corresponding eight-hour TWA air concentration for workers performing parts washing are 0.079 (0.77) mg and 0.0030 (0.028) parts per million by volume (ppm) for historical solvent, and 0.020 (0.20) mg and 0.00078 (0.0075) ppm for current solvent, respectively. Both 95th percentile eight-hour TWA respiratory exposure estimates for solvent formulations are less than 10% of the current Occupational Safety and Health Administration permissible exposure limit of 1.0 ppm for benzene. PMID:20477986

Sheehan, Patrick; Bogen, Kenneth T; Hicks, Jeffrey; Goswami, Emily; Brorby, Gregory; Lau, Edmund C; Ott, Brian

2010-08-01

209

The design of a parabolic reflector system with high tracking tolerance for high solar concentration  

Science.gov (United States)

A compact high concentrating photovoltaic (HCPV) module based on cassegrain optics is proposed; consisting of a primary parabolic reflector, secondary reflector and homogeniser. The effect of parabolic curvatures, reflector separation distance and the homogeniser's height and width on the tracking tolerance has been investigated for optimisation. In this type of HCPV, the addition of a solid transparent homogeniser to the two stage reflector design greatly improves the tracking tolerance. Optical simulation studies show high optical efficiencies of 84.82 - 81.89 % over a range of ±1 degree tracking error and 55.49% at a tracking error of ±1.5 degrees.

Shanks, Katie; Sarmah, Nabin; Reddy, K. S.; Mallick, Tapas

2014-09-01

210

Unexpectedly high indoor hydroxyl radical concentrations associated with nitrous acid.  

Science.gov (United States)

The hydroxyl (OH) radical is the most important oxidant in the atmosphere since it controls its self-oxidizing capacity. The main sources of OH radicals are the photolysis of ozone and the photolysis of nitrous acid (HONO). Due to the attenuation of solar radiation in the indoor environment, the possibility of OH formation through photolytic pathways indoors has been ignored up to now. In the indoor air, the ozonolysis of alkenes has been suggested as an alternative route of OH formation. Models and indirect measurements performed up to now according to this hypothesis suggest concentrations of OH radicals on the order of 10(4)-10(5) molecules per cubic centimeter. Here, we present direct measurements of significant amounts of OH radicals of up to 1.8?10(6) molecules per cubic centimeter during an experimental campaign carried out in a school classroom in Marseille. This concentration is on the same order of magnitude of outdoor OH levels in the urban scenario. We also show that photolysis of HONO is an important source of OH radicals indoors under certain conditions (i.e., direct solar irradiation inside the room). Additionally, the OH concentrations were found to follow a linear dependence with the product J(HONO)?[HONO]. This was also supported by using a simple quasiphotostationary state model on the OH radical budget. These findings force a change in our understanding of indoor air quality because the reactivity linked to OH would involve formation of secondary species through chemical reactions that are potentially more hazardous than the primary pollutants in the indoor air. PMID:23898188

Gómez Alvarez, Elena; Amedro, Damien; Afif, Charbel; Gligorovski, Sasho; Schoemaecker, Coralie; Schoemacker, Coralie; Fittschen, Christa; Doussin, Jean-Francois; Wortham, Henri

2013-08-13

211

Excess Thermodynamic Properties of Concentrated Aqueous Solutions at High Temperatures  

International Nuclear Information System (INIS)

Measurements of the vapor pressure of the solvent in wide ranges of concentration and temperature provide information on solute solvation and ion pairing--the two phenomena most often invoked for description of dilute solutions. Even in moderately concentrated solutions, as interionic distances become comparable to ionic diameters, these simple concepts gradually lose their meaning and solutions behave like molten salts. The usefulness of experimental vapor pressure results increases rapidly with their accuracy, since derived properties, such as solution enthalpies and heat capacities, can be calculated. Very accurate results can be obtained by the isopiestic method, but primary vapor pressure data for standard solutions are needed. In order to obtain vapor pressures at conditions where accurate isopiestic standards are not available and to establish more accurate standards, the ORNL isopiestic apparatus was modified for simultaneous direct vapor pressure measurements and isopiestic comparisons. There are no comprehensive solution theories derived from molecular level models and able to predict thermodynamic properties of various electrolytes as the composition changes from dilute solutions to molten salts in a wide range of temperatures. Empirical and semi-empirical models are useful for representation of experimental results, interpretation of measurements of other properties such as conductance., solubility or liquid-vapor partitioning of solutes, and for verification of theoretical predictions. Vapor pressures for aqueous CaCl(sub 2), CaBr(sub 2), LiCl, LiBr, LiI, NaI were measured at temperatures between 380 and 523 K in the concentration range extended to water activities below 0.2 (over 30 mol/kg for LiCl). General equations based on the modified Pitzer ion-interaction model were used to obtain enthalpy and heat capacity surfaces, which are compared with direct calorimetric measurements

212

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

Energy Technology Data Exchange (ETDEWEB)

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

Sabourin, P.J.; Sun, J.D.; MacGregor, J.T.; Wehr, C.M.; Birnbaum, L.S.; Lucier, G.; Henderson, R.F. (Inhalation Toxicology Research Institute, Albuquerque, NM (USA))

1990-05-01

213

Low Viscosity Highly Concentrated Injectable Nonaqueous Suspensions of Lysozyme Microparticles  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Subcutaneous injection of concentrated protein and peptide solutions, in the range of 100–400 mg/mL, is often not possible with a 25- to 27-gauge needle, as the viscosity can be well above 50 cP. Apparent viscosities below this limit are reported for suspensions of milled lysozyme microparticles up to nearly 400 mg/mL in benzyl benzoate or benzyl benzoate mixtures with safflower oils through a syringe with a 25- to 27-gauge needle at room temperature. These apparent viscosities were confirm...

Miller, Maria A.; Engstrom, Joshua D.; Ludher, Baltej S.; Johnston, Keith P.

2010-01-01

214

Ion exchange method of obtaining high grade europium concentrates  

International Nuclear Information System (INIS)

The studies of receiving the europium from Gd-Sm-Eu concentrate and the separation of Eu-Gd pair by ion-exchange method on Wofatit KPS x 8 using as eluents ?-HIBA, ammonia lactate and mixed eluent EDTA-ammonia acetate, were carried out. The best results were obtained by the use of ?-HIBA as an eluent (0,1-0,15 M and pH 3,9-4,25). As a result of Eu-Gd pair separation by using ?-HIBA as an eluent, Eu2O3 of purity >=3 N was received. (author)

215

High ambient concentrations of monoterpenes in a Scandinavian pine forest  

Science.gov (United States)

Total monoterpene levels of the order of 100 ?g m -3 were assessed in the summer night air of a typical young planted forest of Scots pine ( Pinus silvestris) in Sweden. These concentrations are much higher than those reported in previous studies of ambient monoterpenes. Predominant species were ?-pinene and 3-carene. Camphene, ?-pinene, myrcene, ?-phellandrene and limonene were other prominent components determined. The monoterpenes were shown to originate almost exclusively from Scots pine and the proportions between them to be characteristic of this conifer species.

Petersson, Göran

216

The influence of chronic high alcohol intake on blood pressure, plasma noradrenaline concentration and plasma renin concentration.  

Science.gov (United States)

1. Sixteen 44-year-old males with chronic high alcohol intake were investigated. Seventeen 44-year-old males with low alcohol intake from the same population served as controls. 2. Plasma noradrenaline concentrations did not differ significantly between individuals with high and low alcohol intake, neither at rest nor after acute stimulation induced by ambulation for 15 min. However, 63% (10 out of 16) of the individuals with high intake showed resting values within the upper quartile range for individuals with low intake. 3. Plasma renin concentration was twice as high (P less than 0.01) in the group with high alcohol intake as in the group with low intake. 4. Systolic as well as diastolic blood pressure was significantly higher (P less than 0.01) in the group with high intake compared with the group with low intake. 5. Sympathetic nerve activity, as defined from measurements of plasma noradrenaline concentration, is not uniformly increased in individuals with chronic high alcohol intake. The mechanism behind the increased plasma renin level as well as the possible role of the renin--angiotensin system in alcohol-induced hypertension remain unsettled. PMID:7032823

Ibsen, H; Christensen, N J; Rasmussen, S; Hollnagel, H; Damkjaer Nielsen, M; Giese, J

1981-12-01

217

Celecoxib concentration predicts decrease in prostaglandin E2 concentrations in nipple aspirate fluid from high risk women  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Epidemiologic studies suggest that long term low dose celecoxib use significantly lowers breast cancer risk. We previously demonstrated that 400 mg celecoxib taken twice daily for 2 weeks lowered circulating plasma and breast nipple aspirate fluid (NAF prostaglandin (PGE2 concentrations in post- but not premenopausal high risk women. We hypothesized that circulating concentrations of celecoxib influenced PGE2 response, and that plasma levels of the drug are influenced by menopausal status. To address these hypotheses, the aims of the study were to determine: 1 if circulating plasma concentrations of celecoxib correlated with the change in plasma or NAF PGE2 concentrations from baseline to end of treatment, and 2 whether menopausal status influenced circulating levels of celecoxib. Methods Matched NAF and plasma were collected from 46 high risk women who were administered celecoxib twice daily for two weeks, 20 subjects receiving 200 mg and 26 subjects 400 mg of the agent. NAF and plasma samples were collected before and 2 weeks after taking celecoxib. Results In women taking 400 mg bid celecoxib, plasma concentrations of the agent correlated inversely with the change in NAF PGE2 levels from pre- to posttreatment. Nonsignificant trends toward higher celecoxib levels were observed in post- compared to premenopausal women. There was a significant decrease in NAF but not plasma PGE2 concentrations in postmenopausal women who took 400 mg celecoxib (p = 0.03. Conclusion In high risk women taking 400 mg celecoxib twice daily, plasma concentrations of celecoxib correlated with downregulation of PGE2 production by breast tissue. Strategies synergistic with celecoxib to downregulate PGE2 are of interest, in order to minimize the celecoxib dose required to have an effect.

Flynn John T

2008-02-01

218

Outdoor NO 2 and benzene exposure in the INMA (Environment and Childhood) Asturias cohort (Spain)  

Science.gov (United States)

Air pollution exposure during pregnancy has been linked to a wide range of negative health effects. NO 2, a traffic pollution marker, and benzene, an industrial pollution indicator, stand out among the types of air pollution linked to these effects. The aim of this work is to show the methodology used to assign exposure levels for both pollutants and preliminary reports in the INMA (Environment and Childhood) Asturias cohort in Spain. This cohort consists of 494 pregnant women and their children, who have been recruited and followed since 2004. Air pollution levels were measured at 67 points by means of passive samplers. The mean NO 2 measured value was 21.2 ?g m -3 (range 3.5 ?g m -3 to 44.5 ?g m -3), and the mean benzene value was 2.72 ?g m -3 (range 0.18 ?g m -3 to 9.17 ?g m -3) at urban sampling points and 0.64 ?g m -3 (range 0.04 ?g m -3 to 2.62 ?g m -3) in rural locations. The Pearson correlation coefficient among pollutants was 0.42. Land Use Regression models were built to predict exposure at the homes of pregnant women. Altitude, road distances and land use were part of the models. The percent of explained variance was 52% for NO 2 and 73% for benzene in the urban zones. No residual autocorrelation was found. Predictions were corrected based on the Air Quality Network of the Principality of Asturias taking into account pregnancy seasonality. Exposure indicators were determined for each term and for the entire pregnancy for each woman. Values for urban locations were higher than those for rural and benzene estimations for 5% of the cohort women were above the European Union annual limit value. Air pollution exposure for the INMA-Asturias cohort clearly depends on the place of residence. In particular, benzene concentrations are remarkably high if an individual lives in an urban and industrial area, which is an issue of management intervention and regulatory concern. Exposure assessment for different pollutants will allow us to evaluate potential adverse effects in foetal and infant health caused by air pollution.

Fernández-Somoano, Ana; Estarlich, Marisa; Ballester, Ferran; Fernández-Patier, Rosalía; Aguirre-Alfaro, Amelia; Herce-Garraleta, Ma Dolores; Tardón, Adonina

2011-09-01

219

Benzene···acetylene: a structural investigation of the prototypical CH···? interaction.  

Science.gov (United States)

The structure of a prototype CH···? system, benzene···acetylene, has been determined in the gas phase using Fourier-transform microwave spectroscopy. The spectrum is consistent with an effective C(6v) structure with an H···? distance of 2.4921(1) Å. The HCCH subunit likely tilts by ~5° from the benzene symmetry axis. The dipole moment was determined to be 0.438(11) D from Stark effect measurements. The observed intermolecular distance is longer than in similar benzene···HX complexes and than the distances observed in the benzene···HCCH cocrystal and predicted by many high level ab initio calculations; however, the experimentally estimated binding energy of 7.1(7) kJ mol(-1) is similar to previously studied benzene···HX complexes. Several additional sets of transitions were observed in the rotational spectrum, likely corresponding to excited states arising from low energy intermolecular vibrational modes of the dimer. PMID:24686437

Ulrich, Nathan W; Seifert, Nathan A; Dorris, Rachel E; Peebles, Rebecca A; Pate, Brooks H; Peebles, Sean A

2014-05-21

220

Preliminary assessment of air quality for carbon monoxide and benzene in the Netherlands under EU legislation  

Energy Technology Data Exchange (ETDEWEB)

Before implementing the second European directive, the member states of the European Union should assess the air quality for carbon monoxide and benzene in their countries. Checks against the limit values show no exceedances in the Netherlands in 2000. The concentrations of benzene and carbon monoxide show a downward trend. A further decrease in both components is expected. If the air quality is only determined on the basis of measurements, a total of 15 measurement stations will be compulsory in the Netherlands for measuring carbon monoxide and 19 for benzene. The requirement for carbon monoxide can be met if the current LML stations are classified differently. For benzene, the current configuration is not sufficient. As the concentrations are expected to decrease further, the choice here has been for a combination of new monitors with additional instruments to assess the air quality.

Folkert, R.J.M.; Jimmink, B.A.; Noordijk, H.

2002-07-01

 
 
 
 
221

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

Science.gov (United States)

Measurement of urinary excretion of the benzene metabolites S-phenylmercapturic acid (S-PMA) and trans,trans-muconic acid (t,t-MA) has been proposed for assessing benzene exposure, in workplaces with relatively high benzene concentrations. Excretion of S-PMA and t,t-MA in underground workers at an oil shale mine were compared with the excretion in workers engaged in various production assignments above ground. In addition, possible modifying effects of genetic polymorphisms in glutathione S-transferases T1 (GSTT1), M1 (GSTM1), and P1 (GSTP1) on the excretion of S-PMA and t,t-MA were investigated. Fifty underground workers and 50 surface workers participated. Blood samples and three urine samples were collected from each worker: (a) a preshift sample collected the morning after a weekend, (b) a postshift sample 1 collected after the first shift, and (c) a postshift sample 2 collected after the last shift of the week. Personal benzene exposure was 114 +/- 35 mug/m(3) in surface workers (n = 15) and 190 +/- 50 mug/m(3) in underground workers (n = 15) in measurements made prior to the study. We found t,t-MA excretion to be significantly higher in underground workers after the end of shifts 1 and 2 compared with the corresponding surface workers. The same picture, although not significant, was seen for S-PMA excretion. Excretion of S-PMA and t,t-MA was found to increase significantly during the working week in underground workers but not in those employed on the surface. Both t,t-MA and S-PMA excretion were significantly higher in smokers compared with nonsmokers. Subjects carrying the GSTT1 wild-type excreted higher concentrations of S-PMA than subjects carrying the null genotype, suggesting that it is a key enzyme in the glutathione conjugation that leads to S-PMA. The results support the use of benzene metabolites as biomarkers for assessment of exposure at modest levels and warrant for further investigations of health risks of occupational benzene exposure in shale oil mines. PMID:15533900

Sørensen, Mette; Poole, Jason; Autrup, Herman; Muzyka, Vladimir; Jensen, Annie; Loft, Steffen; Knudsen, Lisbeth E

2004-11-01

222

Adverse effect of high glucose concentration on stem cell therapy.  

Science.gov (United States)

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. PMID:24505533

Saki, Najmaldin; Jalalifar, Mohammad Ali; Soleimani, Masoud; Hajizamani, Saeideh; Rahim, Fakher

2013-01-01

223

Adverse Effect of High Glucose Concentration on Stem Cell Therapy  

Directory of Open Access Journals (Sweden)

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.

Najmaldin Saki

2013-07-01

224

Anaerobic benzene oxidation by Geobacter species.  

Science.gov (United States)

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

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

2012-12-01

225

Anaerobic benzene oxidation by Geobacter species  

DEFF Research Database (Denmark)

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 × 109 and 8.4 × 109 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 × 109 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. © 2012, American Society for Microbiology.

Zhang, Tian; Bain, Timothy S.

2012-01-01

226

Reusable chelating resins concentrate metal ions from highly dilute solutions  

Science.gov (United States)

Column chromatographic method uses new metal chelating resins for recovering heavy-metal ions from highly dilute solutions. The absorbed heavy-metal cations may be removed from the chelating resins by acid or base washes. The resins are reusable after the washes are completed.

Bauman, A. J.; Weetal, H. H.; Weliky, N.

1966-01-01

227

Boeing high-efficiency low-cost concentrated photovoltaic technology  

Science.gov (United States)

The Boeing CPV system has been developed as a jointly funded effort between the Boeing companies, its industrial partners and the Department of Energy. As with all commercial solar systems the key driver of success is a production cost which is competitive with existing power sources. In this paper we describe an approach for driving the near term cost and LCOE (levelized cost of energy) of less than 0.10 per kWh with growth opportunities down to 0.07 per kWh. This objective is achievable through a combination of existing high performance optics, the future availability of +40% to 50% conversion efficient multi-junction cells, low cost design tailored to high speed and low cost manufacturing, field assembly, and low cost trackers.

Hall, John C.; Martins, Guy L.; Cameron, Michael; Marks, Stuart

2011-10-01

228

[Personal exposures of benzene treated workers and a simple biological monitoring].  

Science.gov (United States)

A simple method of biological monitoring has been developed for occupational benzene exposure. Personal benzene exposure monitoring using a passive sampler and GC/FID was carried out on 74 workers from a benzene-treated company. Their urines were collected before and after work-shift. After treatment of urine samples using solid phase extraction (SPE), trans, trans-muconic acid(t, t-MA) concentration in the elute was analysed by HPLC. Correlation between benzene exposure (X: ppm) and urinary t, t-MA concentration (Y: mg/g x creatinine) for non-smokers was Y = 0.948X + 0.586 (r = 0.798, P < 0.01) and Y = 0.885X + 0.894 (r = 0.871, P < 0.01) for smokers, respectively. The t, t-MA concentration on 1 ppm TLV exposure to benzene was estimated as 1.5 and 1.8 (mg/g creatinine) for non-smokers and smokers, respectively. These values are in agreement with some investigators. This indicates that our simple method for biological monitoring of benzene exposure can be of great service. PMID:15794595

Yamauchi, Tsuneyuki; Onodera, Chika; Okada, Takayuki; Yamada, Kenichi; Takata, Tsutomu; Kadowaki, Takehiro; Murayama, Tomiko; Uchiyama, Iwao; Goto, Sumio

2005-03-01

229

Adverse Effect of High Glucose Concentration on Stem Cell Therapy  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

Najmaldin Saki; Mohammad Ali Jalalifar; Masoud Soleimani; Saeideh Hajizamani; Fakher Rahim

2013-01-01

230

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...building operations called tire building machine operators, who use solvents containing...passing the carbon disulfide through 13x molecular sieve). 4.2. Benzene, reagent...ideal gas 25 °C and 760 mm 78.11=molecular weight of benzene 8. Backup...

2010-07-01

231

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

... III. Signs and Symptoms Direct skin contact...the skin. Local effects of benzene vapor...initial stimulatory effect on the central nervous...followed by a period of depression, drowsiness... The detrimental effect on the blood-forming...Early signs and symptoms of benzene...

2010-07-01

232

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...Use non-sparking tools to open benzene containers which are...section of charcoal and broken open. The glass wool is removed...Carbon disulfide from a number of sources was analyzed for benzene contamination...liquid chromatograph are: 1. Mobile phase—Methyl...

2010-07-01

233

Bio sensing Benzene in the refinery  

International Nuclear Information System (INIS)

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

234

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...Container means any barrel, bottle, can, cylinder, drum, reaction vessel, storage tank...Benzine do not contain benzene). 2. Formula: C6 H6 (CAS Registry Number...C and 760 mm 78.11=molecular weight of benzene 8. Backup Data. 8.1...

2010-07-01

235

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...benzene. Chemical Abstracts...vapor control systems for all...monitoring. Engineering and work...containers or process equipment...days of the introduction of benzene...subsequent chemical analysis...monitoring systems, passive...one lot of chemical to another...desorption process,...

2010-07-01

236

Response of a concentrated monoclonal antibody formulation to high shear.  

Science.gov (United States)

There is concern that shear could cause protein unfolding or aggregation during commercial biopharmaceutical production. In this work we exposed two concentrated immunoglobulin-G1 (IgG1) monoclonal antibody (mAb, at >100 mg/mL) formulations to shear rates between 20,000 and 250,000 s(-1) for between 5 min and 30 ms using a parallel-plate and capillary rheometer, respectively. The maximum shear and force exposures were far in excess of those expected during normal processing operations (20,000 s(-1) and 0.06 pN, respectively). We used multiple characterization techniques to determine if there was any detectable aggregation. We found that shear alone did not cause aggregation, but that prolonged exposure to shear in the stainless steel parallel-plate rheometer caused a very minor reversible aggregation (<0.3%). Additionally, shear did not alter aggregate populations in formulations containing 17% preformed heat-induced aggregates of a mAb. We calculate that the forces applied to a protein by production shear exposures (<0.06 pN) are small when compared with the 140 pN force expected at the air-water interface or the 20-150 pN forces required to mechanically unfold proteins described in the atomic force microscope (AFM) literature. Therefore, we suggest that in many cases, air-bubble entrainment, adsorption to solid surfaces (with possible shear synergy), contamination by particulates, or pump cavitation stresses could be much more important causes of aggregation than shear exposure during production. PMID:19370772

Bee, Jared S; Stevenson, Jennifer L; Mehta, Bhavya; Svitel, Juraj; Pollastrini, Joey; Platz, Robert; Freund, Erwin; Carpenter, John F; Randolph, Theodore W

2009-08-01

237

Effects of the principal hydroxy-metabolites of benzene on microtubule polymerization.  

Science.gov (United States)

The principal hydroxy-metabolites of benzene - phenol, catechol and hydroquinone - possess characteristics and produce toxicity similar to those reported for certain inhibitors of microtubule polymerization. In this study we examined the effects of phenol, catechol and hydroquinone on purified microtubule polymerization and the decay of tubulin-colchicine binding activity. Hydroquinone, but not catechol or phenol, inhibited microtubule polymerization and accelerated the decay of tubulin-colchicine binding activity. The latter effect was shown to be dependent on the concentration of GTP. Hydroquinone did not directly complex with GTP or ATP but bound to the high molecular weight fraction of tubulin. concentration ratios of hydroquinone to tubulin resulting in altered activity were low, suggesting a specific interaction, presumably at the tubulin-GTP binding site. The acceleration of tubulin-colchicine binding activity decay was completely prevented under anaerobic conditions, indicative of an oxidative mechanism. These studies suggest that hydroquinone, which auto-oxidizes, may interfere with microtubule function, nucleotide binding or both and that this mechanism may be involved in eliciting the wide range of cytoskeletal-related abnormalities observed in cells exposed to benzene in vivo or its metabolites in vitro. PMID:7447702

Irons, R D; Neptun, D A

1980-10-01

238

Pyridine prevents the clastogenicity of benzene but not of benzo[a]pyrene or cyclophosphamide.  

Science.gov (United States)

Pyridine has been shown to be a much more potent inhibitor than other solvents of the metabolism and therefore the clastogenicity of benzene. In this report, pyridine prevented benzene-derived micronucleus formation in the bone marrow of ICR Swiss mice at much lower levels than xylene did. Time-course experiments did not indicate any delay in the peak micronucleus response to benzene caused by either pyridine or xylene. Similar experiments using pyridine with benzo[a]pyrene and pyridine with cyclophosphamide indicated that the effect of pyridine was specific for benzene. Benzo[a]pyrene (150 mg/kg) was inhibited by pyridine only at levels of 100 mg/kg or more, compared to inhibition of benzene (440 or 880 mg/kg) by pyridine at levels of 5 mg/kg. Cyclophosphamide was not inhibited at any level, and micronucleus formation was increased at lower ratios of pyridine to cyclophosphamide. These results provide indirect conformation of the work by others indicating that benzene is activated in part by a cytochrome P450 isozyme different from those activating benzo[a] pyrene or cyclophosphamide. Since DBA/2 mice (AHH-non-inducible) are more sensitive to benzene than C57Bl/6 mice (AHH-inducible), single and multiple treatments with benzene were compared by micronucleus response in these two strains. DBA mice were more responsive in all cases. Pretreatment with methylcholanthrene caused a greater response to benzene in DBA/2 mice, suggesting that the cytochrome P450 isozyme involved is one of the forms induced by methylcholanthrene independent of the high-affinity Ah receptor. It is hypothesized that more efficient activation of benzene by the unique cytochrome P450 isozyme, perhaps combined with relatively less conjugation, may result in a greater sensitivity of the bone marrow versus the liver, and of DBA/2 versus C57Bl/6 mice. PMID:3037363

Harper, B L; Legator, M S

1987-07-01

239

Development of particle-sizing for high concentrated colloidal dispersions based on photon correlations spectroscopy  

International Nuclear Information System (INIS)

Particle-sizing in colloidal dispersions by dynamic light scattering is restricted to the low-concentration regime. This report shows the development of the above mentioned technique to very high concentrations. The apparatus consists in the main part of a fiber-optic spectrometer; data acquisition and interpretation in done conventionally. The apparent systematic deviations of the particle diameter - evaluated from the diffusion coefficient - to the real particle size as a function of particle concentration is up to a high concentration due to particle-particle-interaction. The described experimental technique enables the measurement of particle diffusion coefficients even in very high concentrated colloidal dispersions. (orig.)

240

A method for treating straight-run benzene fractions  

Energy Technology Data Exchange (ETDEWEB)

The method for treating straight-run benzene fractions, which involves platforming the original raw material, separating the platforming products into low-boiling and settling fractions with the final exposure of the settling fraction to Fe-Cr-Ni catalyst in the presence of water vapor and then mixing the exposed products with a low boiling point fraction, is improved by separating the platforming products and producing a low boiling point fraction which boils out at equal to or less than 85-110 degrees in order to improve the quality of the high octane benzene produced. For example, a straight-run benzene fraction is subjected to platforming at 50-182 degrees in the presence of Pt/Al/sub 2/O/sub 3/ catalyst at 490 degrees, 40 atmospheres, volumetric rate of raw material injection 1.5 hours/sup -1/ and the rate of circulating H/sub 2/-containing gas 1000 m/sup 3//m/sup 3/ of raw material. The platformate is separated into a fraction with a low boiling point of 85 degrees and a settling fraction. The latter is exposed to a Fe-Cr-Ni catalyst at 745 degrees, 1 atmosphere of pressure, volumetric rate 2 hours/sup -1/, with the ratio of water vapor to raw material 2. The exposed products are mixed with the low boiling point platformate fraction and produce 99 octane benzene which contains 60.4 percent aromatic hydrocarbons.

Tanatarov, M.A.; Akhmetov, A.F.; Akhmetshina, M.N.; Prusenko, B.E.; Sarmanaev, R.S.; Valifov, R.B.

1982-01-01

 
 
 
 
241

Thermodynamic study of benzene and hydrogen coadsorption on Pd(111).  

Science.gov (United States)

Periodic density functional theory (DFT) has been used to study the coadsorption of hydrogen and benzene on Pd(111). The most stable coverages are predicted by constructing the thermodynamic phase diagram as a function of gas-phase temperature and pressure. The common approximation that neglects vibrational contributions to the surface Gibbs free energy, using the PW91 functional, is compared to the one that includes vibrational contributions. Higher coverages are predicted to be thermodynamically the most stable including vibrational frequencies, mainly due to the different entropy contributions. The first approach is also compared to the one using a (optPBE-vdW) vdW-DF functional without vibrational contributions, which predicts higher benzene coverages for benzene adsorption, and lower hydrogen coverages for hydrogen adsorption and coadsorption with a fixed benzene coverage. Inclusion of vibrational contributions using the vdW-DF method has not been implemented due to computational constraints. However, an estimate of the expected result is proposed by adding PW91 vibrational contributions to the optPBE-vdW electronic energies, and under typical hydrogenation conditions high coverages of about ?H = 0.89 are expected. Inclusion of vibrational contributions to the surface Gibbs free energy and a proper description of van der Waals interaction are recommended to predict the thermodynamically most stable surface coverage. PMID:25271890

Canduela-Rodriguez, Gonzalo; Sabbe, Maarten K; Reyniers, Marie-Françoise; Joly, Jean-François; Marin, Guy B

2014-11-21

242

[Study on catalytic oxidation of benzene by microwave heating].  

Science.gov (United States)

The performance in catalytic oxidation of benzene was investigated in two different heating modes, microwave heating and conventional electric furnace heating. The effects of copper (Cu)-manganese (Mn) mass ratio, doping dose of cerium (Ce) and calcination temperature on the catalytic activity of Cu-Mn-Ce/molecular sieve catalyst were also checked in catalytic oxidation of benzene with microwave heating, and the catalysts were subsequently characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). The results showed that the catalyst had better catalytic activity for the oxidation of benzene under microwave heating than electric furnace heating, and high oxidation efficiency for benzene was reached due to the "local hot spots" and dipole polarization effect of microwave and stable bed reaction temperature. Under the conditions of Cu, Mn and Ce mass ratio 1:1:0.33 and calcination temperature 500 degrees C, the catalyst had the optimal catalytic activity for benzene oxidation, and its light-off temperature and complete combustion temperature were 165 degrees C and 230 degrees C, respectively. It was indicated by characteristics of XRD and SEM that the presence of copper and manganese oxides and Cu1.5Mn1.5O4 with spinel crystal improved the catalytic activity of the catalyst, and the doping of Ce promoted the dispersion and regularization of active components. High calcination temperature led to the sintering of the catalyst surface and agglomeration of active components, which decreased the catalytic activity of the catalyst in the catalytic oxidation PMID:23213902

Zhang, Yu-cai; Bo, Long-li; Wang, Xiao-hui; Liu, Hai-nan; Zhang, Hao

2012-08-01

243

Photocatalytic monofluorination of benzene by fluoride via photoinduced electron transfer with 3-cyano-1-methylquinolinium.  

Science.gov (United States)

The photocatalytic fluorination of benzene occurs under photoirradiation of an oxygen-saturated acetonitrile (MeCN) of the 3-cyano-1-methylquinolinium ion (QuCN(+)) containing benzene and tetraethylammonium fluoride tetrahydrofluoride (TEAF·4HF) with a xenon lamp (500 W) attached to a colored-glass filter (? laser flash photolysis measurements were performed to elucidate the mechanistic details for photocatalytic fluorination. Transient absorption spectra taken after the nanosecond laser excitation at 355 nm of a degassed MeCN solution of QuCN(+) and benzene exhibited absorption bands due to QuCN(•) (?max = 500 nm) and the benzene dimer radical cation (?max = 900 nm), which were generated by photoinduced electron transfer from benzene to the singlet excited state of QuCN(+). The decay rate of the transient absorption band due to the benzene dimer radical cation was accelerated by the addition of TEAF·4HF. The observed rate constant increased with increasing concentration of TEAF·4HF. The rate constant of the electrophilic addition of fluoride to the benzene radical cation was determined to be 9.4 × 10(9) M(-1) s(-1). Thus, the photocatalytic reaction is initiated by intermolecular photoinduced electron transfer from benzene to the single excited state of QuCN(+). The benzene radical cation formed by photoinduced electron transfer reacts with the fluoride anion to yield the F-adducted radical. However, QuCN(•) can reduce O2 to O2(•-), and this is followed by the protonation of O2(•-) to afford HO2(•). The hydrogen abstraction of HO2(•) from the F-adduct radical affords fluorobenzene and H2O2 as the final products. PMID:24050618

Ohkubo, Kei; Fujimoto, Atsushi; Fukuzumi, Shunichi

2013-10-17

244

Plant responses to high O 2 concentrations: relevance to previous high O 2 episodes  

Science.gov (United States)

Exposure to the ˜ 43 kPa O 2 thouhht to correspond to the highest O 2 partial pressure in the Phanerozoic rather than the 21 kPa in the present atmosphere deleteriously affects extant C 3 land plants by increasing (1) the O 2 inhibition (competitive with CO 2) of the carboxylating enzyme ribulose 1,5 bisphosphate carboxylase-oxygenase, (2) the O 2 inactivation of nitrogenase in symbiotic N 2-fixers, and (3) the generation of reactive oxygen species which can damage nuclei acids, proteins, lipids and other cell constituents. Exposure of these plants to O 2 levels approximating a high O 2 episode inhibits growth via inhibition of ribulose carboxylase and, possibly, by unrepaired damage caused by reactive oxygen species and by the resource diversion related to increasing the capacity of mechanisms reducing the level of reactive oxygen species and to repairing the damage caused by these species. Longer term effects (e.g. increased level of mutations in a population) have not been explored. Natural exposure of all or part of extant plants to O 2 levels in excess of 43 kPa occurs in the light in most plants other than C 3 land plants due to photosynthetic O 2 evolution with restricted diffusion to a medium with normal O 2 levels attendant on the maintenance of high CO 2 concentrations around ribulose 1,5 bisphosphate carboxylase. While the high O 2 levels seem to be restricted where possible to non-meristematic regions of multicellular plants, these plants which have high internal O 2 levels do not seem to be disadvantaged relative to C 3 land plants. The high O 2 concentrations proposed for periods in the Phanerozoic are tolerated, as intracellular O 2 levels, in some cells of a substantial fraction of extant phototrophs, and many can tolerate substantially higher levels. Fire seems more likely than the effects discussed in this paper as limitations on co-occurence of terrestrial vegetation and high O 2 levels.

Raven, John A.

1991-12-01

245

Dielectric relaxation of sulfolane in benzene solution from microwave absorption data  

Science.gov (United States)

The electric constant (?') and dielectric loss (??) for dilute solutions of sulfolane in benzene solution has been measured at 9.885 GHz at different temperatures (25, 30, 35, and 40°C) by using standard microwave techniques. Following the single frequency concentration variational method, the dielectric relaxation time (?) and dipole moment (?) have been calculated. It is found that dielectric relaxation process can be treated as the rate process, just like the viscous flow. Based on the above studies, monomer structure of sulfolane in benzene has been inferred. The presence of solute-solvent associations in benzene solution has been proposed. Energy parameters (? H ?, ? F ?, ? S ?) for dielectric relaxation process of sulfolane in benzene at 25, 30, 35, and 40°C have been calculated and compared with the corresponding energy parameters (? H ?, ? F ?, ? S ?) for the viscous flow.

Singh, Dalip; Thakur, Nagesh; Sharma, D. R.

2011-04-01

246

Pollution characteristics and health risk assessment of benzene homologues in ambient air in the northeastern urban area of Beijing, China.  

Science.gov (United States)

Ambient benzene homologues were measured at a site in the northeastern urban area of Beijing, China, from August 24 to September 4, 2012 by SUMMA canister sampling followed by laboratory determination using cryogenic cold trap pre-concentration-GC-MS/FID, and their health risks were also assessed. Daily total benzene homologues ranged from 0.99 to 49.71 microg/m3 with an average of 11.98 microg/m3. Benzene homologues showed higher concentrations in the morning and evening than that at noontime. Comparison with previous studies revealed a trend of decrease for ambient benzene homologues probably due to the effective emission control in Beijing in recent years. Vehicular exhaust was the main source while volatilization of paints and solvents also made substantial contributions. Health risk assessment showed that BTEX (benzene, toluene, ethylbenzene, o-xylene, m-xylene and p-xylene) and styrene had no appreciable adverse non-cancer health risks for the exposed population, while benzene has potential cancer risk of 1.34E-05. Available data from cities in China all implied that benzene imposes relatively higher cancer risk on the exposed populations and therefore strict control measures should be taken to further lower ambient benzene levels in China. PMID:24649709

Li, Lei; Li, Hong; Zhang, Xinmin; Wang, Li; Xu, Linghong; Wang, Xuezhong; Yu, Yanting; Zhang, Yujie; Cao, Guan

2014-01-01

247

Benzene dynamics and biodegradation in alluvial aquifers affected by river fluctuations.  

Science.gov (United States)

The spatial distribution and temporal dynamics of a benzene plume in an alluvial aquifer strongly affected by river fluctuations was studied. Benzene concentrations, aquifer geochemistry datasets, past river morphology, and benzene degradation rates estimated in situ using stable carbon isotope enrichment were analyzed in concert with aquifer heterogeneity and river fluctuations. Geochemistry data demonstrated that benzene biodegradation was on-going under sulfate reducing conditions. Long-term monitoring of hydraulic heads and characterization of the alluvial aquifer formed the basis of a detailed modeled image of aquifer heterogeneity. Hydraulic conductivity was found to strongly correlate with benzene degradation, indicating that low hydraulic conductivity areas are capable of sustaining benzene anaerobic biodegradation provided the electron acceptor (SO4 (2-) ) does not become rate limiting. Modeling results demonstrated that the groundwater flux direction is reversed on annual basis when the river level rises up to 2?m, thereby forcing the infiltration of oxygenated surface water into the aquifer. The mobilization state of metal trace elements such as Zn, Cd, and As present in the aquifer predominantly depended on the strong potential gradient within the plume. However, infiltration of oxygenated water was found to trigger a change from strongly reducing to oxic conditions near the river, causing mobilization of previously immobile metal species and vice versa. MNA appears to be an appropriate remediation strategy in this type of dynamic environment provided that aquifer characterization and targeted monitoring of redox conditions are adequate and electron acceptors remain available until concentrations of toxic compounds reduce to acceptable levels. PMID:23721190

Batlle-Aguilar, J; Morasch, B; Hunkeler, D; Brouyère, S

2014-01-01

248

Exposures to benzene and other volatile compounds from active and passive smoking  

Energy Technology Data Exchange (ETDEWEB)

Personal exposures and breath concentrations of approximately 20 volatile organics were measured for 200 smokes and 322 nonsmokers in New Jersey and California. Smokers displayed significantly elevated breath levels of benzene, styrene, ethylbenzene, m + p-xylene, o-xylene, and octane. Significant increases in breath concentration with number of cigarettes smoked were noted for the first four aromatic compounds. Based on direct measurements of benzene in mainstream cigarette smoke, it is calculated that a typical smoker inhales 2 mg benzene daily, compared to 0.2 ng/day for the nonsmoker. Thus, cigarette smoking may be the most important source of exposure to benzene for about 50 million citizens of the United States. Passive smokers exposed at work had significantly elevated levels of aromatics in their breath. Indoor air levels in homes with smokers were significantly greater than in nonsmoking home during fall and winter but not during spring and summer. The average annual increase in homes with smokers was 3.6 ..mu..g/m/sup 3/ for benzene and 0.5 ..mu..g/m/sup 3/ for styrene-an approximate 50% relative increase in each case. Thus, exposure to benzene and styrene may be increased for the approximately 60% of children and other nonsmokers living in homes with smokers.

Wallace, L.; Pellizzari, E.; Hartwell, T.D.; Perritt, R.; Ziegenfus, R.

249

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

Directory of Open Access Journals (Sweden)

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.

Sulaiman Siti

2011-08-01

250

Studies on the mechanism of benzene toxicity  

Energy Technology Data Exchange (ETDEWEB)

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.

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

251

Factors influencing the crystallisation of highly concentrated water-in-oil emulsions: A DSC study  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Highly concentrated emulsions are used in a variety of applications, including the cosmetics, food and liquid explosives industries. The stability of these highly concentrated water-in-oil emulsions was studied by differential scanning calorimetry. Crystallisation of the emulsions was initiated by exposing the emulsions to a low temperature. The effects of surfactant type, electrolyte concentration and electrolyte composition in the aqueous phase on emulsion crystallisation temperature were s...

Irina Masalova; Karina Kovalchuk

2012-01-01

252

Composition of thin films between emulsion droplets stabilized by protein, as measured in highly concentrated emulsions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Oil-in-water emulsions stabilized by whey protein and ß-lactoglobulin are extremely stable to coalescence, provided a saturated adsorbed protein layer is present at the droplet surfaces. If this is the case, these emulsions can be concentrated to stable highly concentrated emulsions, in which the droplets are in continuous contact and separated by thin films. The water content in these highly concentrated emulsions could be lowered to such an extent that almost all of the protein in the emul...

Aken, G. A.; Zoet, F. D.; Diederen, J.

2002-01-01

253

Study on a Passive Vapor Feed Direct Methanol Fuel Cell with High Methanol Concentration  

Directory of Open Access Journals (Sweden)

Full Text Available An extensive research has been carried out to improve the performance of direct methanol fuel cells (DMFCs using low methanol concentration below 5 M either in active or passive conditions due to methanol crossover (MCO problem which the methanol crosses over the membrane and reacts directly with oxygen at cathode. However, a low methanol concentration leads to a low energy density of the fuel cell system and a short runtime which cannot meet the requirement of commercialization. Therefore, it is important to use a high concentration of methanol in DMFC to achieve a high energy density. This study was done to improve the performance of passive vapor feed DMFC by using high methanol concentrations from 12 M (molarity to neat methanol. From the results obtained, it was showed that the performance of passive vapor feed DMFC that used high methanol concentration improved. It was a linear dependence of current density on methanol concentration which is the current density increased when the methanol concentration increased up to neat. The linear dependence of current density on the concentration suggested that the cell operation was under the rate controlling by the methanol transport. Therefore, it can conclude that high methanol concentration can leads to high energy density achieved by the DMFCs.

F. A. Halim

2013-10-01

254

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

Science.gov (United States)

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

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

2014-03-10

255

(Liquid + liquid) equilibria of {benzene + cyclohexane + two ionic liquids} at different temperature and atmospheric pressure  

International Nuclear Information System (INIS)

Highlights: ? (Liquid + liquid) equilibrium for two quaternary and two ternary systems were measured. ? The components include cyclohexane, benzene, [MIM][BF4], [MIM][ClO4] and [MMIM][DMP]. ? The (liquid + liquid) equilibrium data can be well correlated by the NRTL model. ? Separation of benzene and cyclohexane by pure ILs and their mixtures were discussed. - Abstract: (Liquid + liquid) equilibrium data of the following ternary and quaternary systems at different temperatures and mass fractions of ionic liquids (ILs) were measured at atmospheric pressure, i.e., {cyclohexane + benzene + 1,3-dimethylimidazolium dimethylphosphate ([MMIM][DMP])} at 298.2 K, {cyclohexane + benzene + 1-methylimidazolium tetrafluoroborate ([MIM][BF4])} at 338.2 K, {cyclohexane + benzene + [MIM][BF4] + [MMIM][DMP]} at (298.2 and 313.2) K, and {cyclohexane + benzene + 1-methylimidazolium perchlorate [MIM][ClO4] + [MMIM][DMP]} at 298.2 K. The results indicate that both selectivity and distribution factor of the IL mixture for benzene are lower than that of pure IL [MMIM][DMP] at a specified condition, and decrease with the increase of the mass fraction of [MIM][BF4] or [MIM][ClO4] in its mixture of [MMIM][DMP] and the mole fraction of benzene. The extremely high selectivity of [MIM][BF4] and [MIM][ClO4] for aromatic compounds as predicted by the COSMOS-RS model is not justified by the present experimental resul by the present experimental results, and on the contrary, they show a relatively lower selectivity and extraction capacity for benzene than [MMIM][DMP].

256

Modifications in the metabolic pathways of benzene in streptozotocin-induced diabetic rat  

Energy Technology Data Exchange (ETDEWEB)

Benzene is a ubiquitous environmental pollutant primarily metabolized by a cytochrome P-450 (CYP-450) isoenzyme, CYP-450 IIE1. A consistent induction of CYP450 IIE1 has been observed in both rat and human affected by diabetes mellitus. The aim of this study was to evaluate whether streptozotocin (STZ)-induced diabetes determines modifications in the metabolic pathways of benzene in rat. Benzene (100 mg/kg per day, dissolved in corn oil) was administered i.p. once a day for 5 days. Urine samples were collected every day in STZ-treated and normoglycaemic animals, treated and untreated with benzene (n = 10). Urinary levels of trans,trans-muconic acid and of phenol, catechol and hydroquinone (free and conjugated with sulphuryl and glucuronic group) were measured by high-performance liquid chromatography (HPLC). In normoglycaemic rats during the 5 days of treatment with benzene we observed a progressive and significant decrement in the urinary excretion of phenol, phenyl sulphate and glucuronide, catechol, catechol glucuronide, hydroquinone, hydroquinone glucuronide and t,t-muconic acid (P < 0.05). In the diabetic animals, conversely, the same metabolites showed progressively increasing urinary levels (P < 0.05). Catechol sulphate and hydroquinone sulphate levels were below the instrument`s detection limit. In the comparison between diabetic and normoglycaemic benzene treated rats, the inter-group difference was significant (P < 0.05) from day 3 of treatment for t,t-muconic acid, and from day 1 for free and conjugated phenol, free and glucuronide catechol and free hydroquinone. In the normoglycaemic rat exposed to benzene the decreasing trend observed in urinary excretion of free and conjugated metabolites may be due to their capability to reduce cytochromial activity. Conversely, in the diabetic rat, urinary levels of benzene metabolites tended to increase progressively, probably due to the consistent induction of CYP-450 IIE1 observed in diabetes, which would overwhelm the inhibition of this isoenzyme caused by phenolic metabolites. Furthermore, the metabolic switch towards detoxification metabolites observed after administration of high doses of benzene is not allowed in the diabetic because of reduced glutathione-S-transferase activity. As a consequence, higher levels of hydroquinone, phenol and catechol, considered the actual metabolites responsibles for benzene toxicity, will accumulate in the diabetic rat. Extrapolating these data to human, we may thus suggest that occupational exposure to benzene of a diabetic subject poses a higher risk level, as his metabolism tends to produce and accumulate higher levels of reactive benzene catabolites. (orig.) With 2 figs., 41 refs.

Costa, C. [Istituto di Medicina del Lavoro, Univ. di Messina (Italy); Pupo, C.; Viscomi, G.; Catania, S.; Salemi, M.; Imperatore, C. [Centro Interdipartimentale di Tossicologia Sperimentale, Univ. di Messina (Italy)

1999-08-01

257

Lithium-Mediated Benzene Adsorption on Graphene and Graphene Nanoribbons  

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The anchoring of benzene molecules on lithium adsorption sites at the surface of graphene and nanoribbons thereof are investigated. The effects of adsorbate densities, specific adsorption locations, and spin states on the structural stability and electronic properties of the underlying graphene derivatives are revealed. At sufficiently high densities, bare lithium adsorption turns armchair graphene nanoribbons metallic and their zigzag counterparts half-metallic due to charg...

Krepel, Dana; Hod, Oded

2013-01-01

258

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...Oil and gas drilling, production and servicing operations. (vii) Coke oven batteries. (3) The cleaning...encountered are: the primary production and utilization of benzene...Guidelines A minimum battery of tests is to be...

2010-07-01

259

Cyanoborohydride-promoted radical arylation of benzene.  

Science.gov (United States)

Radical biaryl coupling of iodoarenes and benzene can be effectively promoted by tetrabutylammonium cyanoborohydride with air under photoirradiation conditions using a Xe lamp. The utility of this methodology is highlighted by its functional group tolerance and chemoselectivity. PMID:24697750

Kawamoto, Takuji; Sato, Aoi; Ryu, Ilhyong

2014-04-18

260

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...measurements are taken in a random manner over the 8-hour work shift. Random sampling means that any portion...arithmetic average of all such random samples taken on one work...Samples Analyte: Benzene Matrix: Air Procedure:...

2010-07-01

 
 
 
 
261

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...section applies to all occupational exposures to benzene. Chemical Abstracts Service Registry No. 71-43-2, except as provided in...Sampling and analysis must be performed with procedures meeting the requirements of the standard. There are a...

2010-07-01

262

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...for earnings lost during the period of removal either from a publicly or employer-funded...possible by virtue of the employee's removal. (j) Communication of benzene hazards...characterized by exhilaration, nervous excitation, and/or giddiness, followed...

2010-07-01

263

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...The carbon disulfide layer is removed, dried with anhydrous sodium sulfate, and distilled. The recovered carbon disulfide...4. Desorption data. Samples were prepared by injecting liquid benzene onto the A section of charcoal...

2010-07-01

264

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...Guidelines, Benzene I. Physical and Chemical Data A. Substance identification. 1. Synonyms: Benzol, benzole, coal naphtha, cyclohexatriene, phene, phenyl hydride, pyrobenzol. (Benzin, petroleum benzin and Benzine do not contain...

2010-07-01

265

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...a number of methods available for monitoring...standard solutions. 4. Reagents. 4.1. Chromatographic...disulfide (CS2 ). Most commercially available carbon disulfide contains... 4.2. Benzene, reagent grade. 4.3....

2010-07-01

266

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...the appearance of red cells. c. Description...smear for immature white cells such as band forms...myeloblasts. Any nucleate or multinucleated red blood cells should be reported. Large...indication of benzene-induced toxicity. An...

2010-07-01

267

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...pattern is more likely to be associated with benzene toxicity and merits thorough investigation. Anemia, leukopenia, macrocytosis or an abnormal differential white blood cell count should alert the physician to further investigate and/or refer...

2010-07-01

268

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...gloves, sleeves, aprons, etc.) over any parts of your body that could be exposed to liquid benzene. C. Eye and...cell and white cell counts are influenced by altitude, race, and sex, and therefore should be determined by the...

2010-07-01

269

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...pulmonary tissue. There is some absorption through the skin. Absorption may be more rapid in the...addition, there is benzene absorption through the skin. Local...that place the employee at increased risk. To assist the...

2010-07-01

270

Secondary organic aerosol formation from the photo-oxidation of benzene  

Science.gov (United States)

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.

Borrás, Esther; Tortajada-Genaro, Luis Antonio

2012-02-01

271

Testing of stripping columns for the removal of benzene from aqueous radioactive salt solution  

International Nuclear Information System (INIS)

Radioactive high level wastes (HLW) generated from production of special nuclear materials at the Savannah River Site (SRS) are held in interim storage in 51 underground, million gallon tanks. Radioactive cesium (137Cs) is segregated by evaporation of aqueous waste solution for interim storage in a salt matrix comprised of Na and K salts or in concentrated salt solution. The saltcake will be dissolved and 137Cs will be separated from the nonradioactive salts in solution in the In-Tank Precipitation (ITP) Process. The cesium will be combined with other radioactive species and glass formers to be melted and poured into stainless steel canisters in the Defense Waste Processing Facility (DWPF). The salt solution remaining after decontamination in the ITP process will be incorporated into grout for disposal at the site's Saltstone facility. In the ITP facility, sodium tetraphenylborate (STPB) will be added to precipitate the cesium. Potassium in the waste solution also reacts with STPB and precipitates. Due to radiolytic and chemical degradation of the tetraphenylborate (TPB) precipitate, benzene is generated. The benzene dissolves into the decontaminated salt solution (DSS) and into water (WW) used to open-quotes washclose quotes the precipitate to lower the soluble salt content of the slurry. Safety and processing requirements for disposal of the DSS and for temporary storage of the WW dictate that the benze

272

A field campaign for measurement of benzene in urban area of Venice  

International Nuclear Information System (INIS)

A field campaign for the measurement of benzene and toluene in urban areas has been planned by the city of Venice in collaboration with CNR during the period June-July 1994. The measurements were provided by three automatic systems, available from the companies Chrompack, Elecos and Perkin-Elmer. The main aims of this campaign were to collect information on spatial and temporal distribution of these pollutants, in order to estimate the exposure risk for people in an urban polluted environment, and to identify the most reliable and accurate systems to measure this pollutant. From the comparison between the temporal trend of benzene and natural radioactivity it can be deduced that the concentration levels of primary pollutants at ground state are not simply linked to emissions, but they are strongly modulated by atmospheric diffusion processes. The reliability of the experimental results was demonstrated by a statistical treatment, and it was shown that it is necessary to carry out measurements at sufficiently high frequencies to represent the real environmental situation

273

Benzene and lead exposure assessment among occupational bus drivers in Bangkok traffic.  

Science.gov (United States)

Four environmental and biological monitoring sites were strategically established to evaluate benzene and lead exposure assessment at various traffic zones of Bangkok Metropolitan Region(BMR). Biological measurement of 48 non air-conditioned, male bus drivers was carried to study the relationship between individual exposure levels and exposure biomarkers. The study group was further subdivided into four age groups(16-25, 26-35, 36-45 and 46-55 years old) to monitor the age-related exposure effects. A total of 12 unexposed persons were deliberately chosen as the control group. Measurement of unmetobolized benzene in blood and analysis of urinary tt-Muconic acid urine and urinary creatinine are recommended as biomarkers of benzene exposure. Measurement of lead in blood and urine is also recommended for the biological monitoring of lead exposure. During the monitoring period, benzene and lead levels at Yaowarat Road was C6H6: 42.46 +/- 3.88 microg/m3 , Pb: 0.29 +/- 0.03 microg/m3 and decreased to C6H6: 33.5 +/- 1.35 microg/m3, Pb: 0.13 +/- 0.01 microg/m3 at Phahonyothin Road. Significant difference was established between the nonsmoking exposed group and nonsmoking control group for blood benzene concentrations (P < 0.001, two-tailed, Mann-Whiteney U test). Strong correlations were also found between trans-trans-Muconic acid concentrations in post shift samples and atmospheric benzene concentrations. Similarly, good correlation between all of biomarkers and lead level in air is established from automobile emissions. The analysis revealed that among the occupational population in the urban sites, the driver groups were found to have the highest risk of benzene and lead exposures derived from automobile emission. PMID:14971454

Muttamara, S; Leong, Shing Tet; Arayasiri, M

2004-01-01

274

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

Science.gov (United States)

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

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

2014-06-30

275

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

276

Drinking and osmoregulation in the mangrove crab Ucides cordatus following exposure to benzene.  

Science.gov (United States)

In benzene-exposed Ucides cordatus acclimated for 96 h to 9 and 34 per thousand SW, haemolymph, urine and gastric juice are isosmotic with each other, but differ significantly in osmolality from external media. In both salinities, under benzene action, urine K+ excretion and calcium absorption are increased significantly, whereas Na+ absorption and Mg2+ excretion show U/B ratios similar to control values. In 9 per thousand SW, some ionic exchanges via benzene-exposed gills are possibly hastened. Benzene exposure decreases significantly branchial chamber water osmolality, [Na+] and [K+], whereas [Ca2+] and [Mg2+] are unaffected. However, faster medium exchange presumably occurs in 34 per thousand SW, both crab groups show branchial chamber water osmotic and ionic concentrations similar to surrounding medium. Benzene exposure unaffected gastric juice composition. In both media, [Ca2+] and [Mg2] accumulate several times higher than surrounding media, and [Na+] and [K+] are significantly hypo-ionic to haemolymph. Na+ and K+ G/H ratios are lower in crabs acclimated to 34 per thousand SW than in crabs acclimated to 9 per thousand SW. Drinking rates are enhanced by benzene exposure and are higher at 34 per thousand SW than in seawater isosmotic with the haemolymph (26 per thousand SW). Benzene exposure affects significantly osmoregulatory capability, slowing haemolymph dilution after transfer to clean 9 per thousand SW. Lower haemolymph dilution rate accounts for higher osmolality, but 48 h after transfer there is no recovery like in control crabs. Haemolymph transfusion experiments suggest an interaction among effects of benzene and hormonal factors, possibly on water influx. PMID:12160870

do Carmo Fernandes Santos, Maria

2002-09-01

277

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

DEFF Research Database (Denmark)

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

Kosiorowska, Anna Katarzyna; Puggaard, Liselotte

2011-01-01

278

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

Science.gov (United States)

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

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

2011-02-01

279

Benzene, toluene, ethyl benzene and xylenes in ambient air and Pinus sylvestris L. needles: a comparative study between Belgium, Hungary and Latvia  

Science.gov (United States)

Concentrations of benzene, toluene, ethyl benzene and xylenes (BTEX) in ambient air and in 1 yr old Pinus sylvestris pine needles were monitored along a busy road, petrol station and rural area of Belgium, Hungary and Latvia in a 1 yr period. To test P. sylvestris as a possible biomonitor for the BTEX concentrations, samples were taken in the four seasons. As the distribution of data was not normal, the level of pollution on different sites and seasons was compared and evaluated by non-parametric tests. The measured air concentrations did not differ significantly from one season to another throughout the year. There were, however, differences between sampling places. The C 2-alkylbenzene and toluene concentrations in the needles were similar in the autumn/winter and spring/summer periods but a significant decrease in their concentration was observed in every place between winter and spring. This effect was less obvious for toluene.

Keymeulen, Regine; Görgényi, Miklós; Héberger, Károly; Priksane, Anda; Van Langenhove, Herman

280

A study of the structure of highly concentrated phases of DNA by X-ray diffraction  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In aqueous solution, pure DNA forms multiple liquid crystalline and crystalline phases whose nature depends on the polymer concentration. The following phase sequence is observed when the DNA concentration increases : isotropic ? cholesteric ? columnar hexagonal ? crystalline phases. The aim of this work is to obtain structural information about the highly concentrated phases formed by 500 Å long DNA molecules — in particular about the crystalline phases — by means of X-ray diffr...

Durand, D.; Doucet, J.; Livolant, F.

1992-01-01

 
 
 
 
281

COSMIC-RAY-MEDIATED FORMATION OF BENZENE ON THE SURFACE OF SATURN'S MOON TITAN  

International Nuclear Information System (INIS)

The aromatic benzene molecule (C6H6)-a central building block of polycyclic aromatic hydrocarbon molecules-is of crucial importance for the understanding of the organic chemistry of Saturn's largest moon, Titan. Here, we show via laboratory experiments and electronic structure calculations that the benzene molecule can be formed on Titan's surface in situ via non-equilibrium chemistry by cosmic-ray processing of low-temperature acetylene (C2H2) ices. The actual yield of benzene depends strongly on the surface coverage. We suggest that the cosmic-ray-mediated chemistry on Titan's surface could be the dominant source of benzene, i.e., a factor of at least two orders of magnitude higher compared to previously modeled precipitation rates, in those regions of the surface which have a high surface coverage of acetylene.

282

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 mechan

283

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

284

Spectroscopic Properties of Ce3+-Doped Oxide Glasses with high Gd2O3 Concentrations  

Science.gov (United States)

Ce3+-doped oxide glasses containing high Gd2 O3 concentration are prepared and their transmission, emission and excitation spectra are measured. Dependence of spectroscopic properties on concentrations of Ce2 O3 and Gd2O3 are analyzed. The results show that the UV cut-off wavelength and the emission peaks show red shift, and Stokes shift increases with Ce2O3 and Gd2O3 concentrations due to the increasing optical basicity of the glasses. The emission intensity decreases with increased Ce2O3 and Gd2 O3 concentrations and showing the concentration quenching effect. The red shift of excitation peak is less when the Gd2O3 concentration increases, indicating that the energy transfer from Gd3+ to Ce3+ takes place in the oxide glasses with high Gd2O3 concentrations, and thus Gd3+ ions sensitize the luminescence of Ce3+ ions. The Ce3+ doped oxide glasses with high Gd2O3 concentrations will be a promising scintillator for applications in the high-energy physics and other fields.

Lai, Fei; Zhang, Yue-Pin; Xia, Hai-Ping; Wang, Jin-Hao; Jiang, Chun

2013-09-01

285

Dermal exposure assessment to benzene and toluene using charcoal cloth pads.  

Science.gov (United States)

Charcoal cloth pads have been used to assess volatile chemicals on the skin in a laboratory setting; however, they have not yet been applied to measure dermal exposure in occupational settings. This study aimed at evaluating whether charcoal pads can be used to assess dermal exposure to benzene and toluene in workers of a petrochemical plant. Inhalation and dermal exposure levels to benzene and toluene were assessed for workers of a petrochemical plant performing different jobs. Benzene uptake was assessed by determining S-phenylmercapturic acid in workers' urine samples. Dermal exposure levels on the charcoal pads were adjusted for ambient air levels of benzene and toluene by subtracting the amount of benzene or toluene measured in personal air from the amount of benzene or toluene measured on the charcoal pad. In general, measured external and internal exposure levels were low. The estimated contribution of the dermal route to internal benzene exposure levels was less than 0.06% for all jobs. Toluene personal air concentrations and benzene and toluene dermal exposure levels differed statistically significantly between job titles. For benzene, differences between jobs were larger for adjusted dermal exposures (maximum 17-fold, P = 0.02) than for inhalation exposures (maximum two-fold, P = 0.08). Also for toluene, although less clear, differences between jobs were larger for adjusted dermal exposures (maximum 23-fold, P = 0.01) as compared to inhalation exposures (maximum 10-fold, P = 0.01). Charcoal pads appeared to measure dermal exposures to benzene and toluene in addition to ambient air levels. Future studies applying charcoal cloth pads for the dermal exposure assessment at workplaces with higher dermal exposure to organic solvents may provide more insight into the biological relevance of dermal exposure levels measured by charcoal cloth pads. In addition, the design of the dermal sampler might be improved by configuring a dermal sampler, where part of the sampler is protected against direct contact and splashes, but still permeable for the gas phase. This design would most likely result in a better ability to correct for airborne concentrations at a given body location. PMID:15083162

van Wendel de Joode, Berna; Tielemans, Erik; Vermeulen, Roel; Wegh, Hillion; Kromhout, Hans

2005-01-01

286

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

1982-04-01

287

Evaluation of assays for the identification and quantitation of muconic acid, a benzene metabolite in human urine  

Energy Technology Data Exchange (ETDEWEB)

Muconic acid (MA) is a urinary metabolite of benzene and has been used as a biomarker of exposure to benzene in humans exposed to levels as low as 1 ppm. We have modified a high-pressure liquid chromatography (HPLC) based assay for urinary MA by the use of a diode array detector. This modification increases the specificity of the HPLC-based assay by identifying false positives. In addition, we have developed a gas chromatography (GC) based assay that uses a flame ionization detector (GC-FID). Both assays identified and quantified MA in human urine at concentrations greater than 40-50 ng/ml. Assay precision was within 10% relative standard deviation for MA concentrations above 90 ng/ml using the HPLC assay and above 40 ng/ml using the GC-FID assay. Quantitative accuracy of the assays was evaluated by determining MA in human urine samples using both methods and also a gas chromatography-mass spectrometry (GC-MS) procedure. Numerical correlation among the three assays was good at MA concentrations above 100 ng/ml. 26 refs., 3 figs., 2 tabs.

Bartczak, A.; Kline, S.A.; Yu, R.; Weisel, C.P.; Goldstein, B.D.; Witz, G. [Univ. of Medicine and Dentistry of New Jersey, Piscataway, NJ (United States); Bechtold, W.E. [Inhalation Toxicology Research Institute, Albuquerque, NM (United States)

1994-12-31

288

High concentrations of glucose reduce the oxidative metabolism of dog neutrophils in vitro  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Dogs are commonly affected by hyperglycemic conditions. Hyperglycemia compromises the immune response and favors bacterial infections; however, reports on the effects of glucose on neutrophil oxidative metabolism and apoptosis are conflicting in humans and rare in dogs. Considering the many complex factors that affect neutrophil oxidative metabolism in vivo, we investigated in vitro the specific effect of high concentrations of glucose on superoxide production and apoptosis rate in neutrophils from healthy dogs. Results The capacity of the neutrophils to reduce tetrazolium nitroblue decreased significantly in the higher concentration of glucose (15.13 ± 9.73% (8 mmol/L versus 8.93 ± 5.71% (16 mmol/L. However, there were no changes in tetrazolium nitroblue reduction at different glucose concentrations when the neutrophils were first activated with phorbol myristate acetate. High concentrations of glucose did not affect the viability and apoptosis rate of canine neutrophils either with or without prior camptothecin stimulation. This study provides the first evidence that high concentrations of glucose inhibit the oxidative metabolism of canine neutrophils in vitro in a manner similar to that which occurs in humans, and that the decrease in superoxide production did not increase the apoptosis rate. Conclusions A high concentration of glucose reduces the oxidative metabolism of canine neutrophils in vitro. It is likely that glucose at high concentrations rapidly affects membrane receptors responsible for the activation of NADPH oxidase in neutrophils; therefore, the nonspecific immune response can be compromised in dogs with acute and chronic hyperglycemic conditions.

Bosco Anelise M

2013-02-01

289

Radiolysis of benzene solutions in aqueous NaNO3  

International Nuclear Information System (INIS)

The radiolysis of aqueous benzene solutions was carried out at 35 deg C, 45 deg C, 55 deg C and 65 deg C. The results, obtained by coupling HPLC and GC separations, showed that the yields of all the radiolysis products increased with temperature. However, the comparison of the results must be limited to those compounds that are formed exclusively in aqueous solutions. It was found that the increase of the relative concentrations of the products with the temperature followed the order: nitrobenzene > phenol > o-nitrophenol > p-nitrophenol. (author) 7 refs.; 4 tabs

290

Inhibition of pure cultures of methanogens by benzene ring compounds.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

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

1991-01-01

291

Measurement of High Concentration DOP Aerosols by a Laser Dust Counter  

International Nuclear Information System (INIS)

Light-scattering technique is widely used in industries to measure the particle size distribution and the particle number concentration of aerosols. The number concentration of aerosol is limited in dilute samples less than 100 particles per cm3. A laser dust counter was applied to measure DOP aerosols with high concentration and poly-dispersed particle-size distribution. The results show that the measurement of particle number concentration can be made to 105 particles per cm3 of the particle size range 0.1 to 0.5 micrometers. These results are compared with those obtained by electric aerosol size analyzer and cascade impactor

292

Effective surface dilatational viscosity of highly concentrated particle-laden interfaces  

CERN Document Server

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.

Lishchuk, S V

2014-01-01

293

Synergic extraction of lanthanoid(III) with 2-thenoyltrifluoroacetone and triphenylarsine oxide in benzene  

International Nuclear Information System (INIS)

The synergic extraction of La(III), Eu(III) and Lu(III) with 2-thenoyltrifluoroacetone (Htta) and triphenylarsine oxide (tpao) in benzene was studied. The extractability of lanthanoids, Ln(III), is significantly affected by the association of Htta with tpao in the organic phase. The associated species is Htta · tpao and the association constant is determined as 101.63. The intrinsic extraction equilibrium of Ln(III) is analyzed using the free concentration of Htta and tpao. The synergic enhancement is ascribable to the formation of the adduct complexes shown as Ln(tta)3tpao and Ln(tta)3(tpao)2 in the present extraction system. The adduct formation constants determined are very large as expected from the high basicity of tpao. (author) 13 refs.; 5 figs.; 2 tabs

294

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

Science.gov (United States)

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 °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.

Mayne, Martine; Grobert, Nicole; Terrones, Mauricio; Kamalakaran, Radha; Rühle, Manfred; Walton, David R. M.; Kroto, Harold W.

2001-11-01

295

Determining granular activated carbon adsorption isotherms of benzene as a volatile organic compound  

Energy Technology Data Exchange (ETDEWEB)

Development of a new method using a headspace auto-sampler and gas chromatograph system to determine the adsorption isotherm of benzene as a volatile organic compound for granular activated carbon is described. The method was utilized to measure the adsorption of benzene on Filtrasorb 300 granular activated carbon to determine the Freundlich isotherm parameters. Results confirmed the reliability of the technique for the determination of the activated carbon adsorption of benzene. A review of the literature showed that Freundlich isotherm parameters vary widely from one study to another. The variation is attributed to differences in carbon and water, equilibrium concentration ranges and the testing techniques used. Present theoretical models do not explain the effect of all major contributing factors on the adsorption process, therefore when comparing adsorption capacity of activated carbon, special attention should be paid to the equilibrium concentration. 13 refs., 4 tabs., 4 figs.

Peng, J.; Cui, W.; Wilson, G. W. [Saskatchewan Univ., Dept. of Civil Engineering, Saskatoon, SK (Canada); Lin, W. [North Dakota State Univ., Fargo, ND (United States)

2000-07-01

296

Electrochemical radiofluorination. Labeling of benzene with [18F]fluoride by nucleophilic substitution  

International Nuclear Information System (INIS)

18F-labeling of aromatic compounds normally is achieved by electrophilic substitution. In that case [18F]fluoride cannot be applied although it is produced very efficiently at medical cyclotrons. By the use of electrochemical methods, however, benzene can be oxidized and thus, the electron density is reduced in a way that nucleophilic attack of [18F]fluoride occurs. For the first time benzene was shown to be labeled with [18F]fluoride after being electrochemically oxidized in a 2 ml electrolysis cell with 0.033M Et3N x 3HF and 0.066M Et3N x HCl in CH3CN and benzene in various concentrations. After 50 Coulombs (60-90 min) maximum of labeling was reached. With the highest concentration of aromatic compound (1.0M) the radiochemical yields were 16±9% with specific activities up to 27 GBq/mmol. (author)

297

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

298

Thermophilic biofiltration of benzene and toluene.  

Science.gov (United States)

In the current studies, we characterized the degradation of a hot mixture of benzene and toluene (BT) gases by a thermophilic biofilter using polyurethane as packing material and high-temperature compost as a microbial source. We also examined the effect of supplementing the biofilter with yeast extract (YE). We found that YE substantially enhanced microbial activity in the thermophilic biofilter. The degrading activity of the biofilter supplied with YE was stable during long-term operation (approximately 100 d) without accumulating excess biomass. The maximum elimination capacity (1,650 g x m(-3) h(-1)) in the biofilter supplemented with YE was 3.5 times higher than that in the biofilter without YE (470 g g x m(-3) h(-1)). At similar retention times, the capacity to eliminate BT for the YE-supplemented biofilter was higher than for previously reported mesophilic biofilters. Thus, thermophilic biofiltration can be used to degrade hydrophobic compounds such as a BT mixture. Finally, 16S rDNA polymerase chain reaction-DGGE (PCR-DGGE) fingerprinting revealed that the thermophilic bacteria in the biofilter included Rubrobacter sp. and Mycobacterium sp. PMID:18167445

Cho, Kyung-Suk; Yoo, Sun-Kyung; Ryu, Hee Wook

2007-12-01

299

Desalination of effluents with highly concentrated salt by nanofiltration: From laboratory to pilot-plant  

DEFF Research Database (Denmark)

Nanofiltration (NF) has been widely used for treatment of industrial effluents, but very few work concerns NF process in concentrated saline solution, especially for NF-desalination aiming at permeation of monovalent salts and retention of organic solutes. In this study, NF270 membrane was chosen to treat model solutions and three industrial effluents with highly concentrated salt (crude iron dextran solution, iminodiacetic acid mother liquor, and raw soy sauce), showing that with increase of salt concentration, the retention of all the solutes decreased while concentration polarization was increased. In the presence of charged organic solutes, inorganic salt retention would decline, even negative retention of monovalent salt was found. Increasing pH would induce membrane swelling in saline solution, which might be caused by the higher local salt concentration around the membrane polymers at higher pH. As NF-desalination of industrial effluents with highly concentrated salt was scaled up from laboratory to pilot-plant, the dead-end stirred filtration at constant flux could provide some important information for pilot-plant tests, such as membrane selection, optimum operating parameters and mechanism analysis, but it was necessary to re-optimize operating mode and method for crossflow filtration at constant pressure, in order to control the concentration polarization at high salt concentration.

Luo, Jianquan; Wan, Yinhua

2013-01-01

300

High concentrations of cadmium, cerium and lanthanum in indoor air due to environmental tobacco smoke  

International Nuclear Information System (INIS)

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.

 
 
 
 
301

Factors influencing the crystallisation of highly concentrated water-in-oil emulsions: A DSC study  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english Highly concentrated emulsions are used in a variety of applications, including the cosmetics, food and liquid explosives industries. The stability of these highly concentrated water-in-oil emulsions was studied by differential scanning calorimetry. Crystallisation of the emulsions was initiated by e [...] xposing the emulsions to a low temperature. The effects of surfactant type, electrolyte concentration and electrolyte composition in the aqueous phase on emulsion crystallisation temperature were studied. Surfactant type affected the emulsion crystallisation temperature in the following order: PIBSA-MEA=PIBSA-UREA

Karina, Kovalchuk; Irina, Masalova.

302

The role of benzene photolysis in Titan haze formation  

Science.gov (United States)

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.

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

2014-05-01

303

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.

304

Anaerobic benzene oxidation via phenol in Geobacter metallireducens  

DEFF Research Database (Denmark)

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 (<0.5 mu M) of phenol accumulated in cultures of 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 O-18 during growth in (H2O)-O-18, 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.

Zhang, Tian; Tremblay, Pier-Luc

2013-01-01

305

Anaerobic benzene oxidation via phenol in Geobacter metallireducens.  

Science.gov (United States)

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

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

2013-12-01

306

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

Science.gov (United States)

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.

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

2013-07-01

307

Kinetics of granulocytic and erythroid progenitor cells are affected differently by short-term, low-level benzene exposure  

Energy Technology Data Exchange (ETDEWEB)

Mice were exposed to either air or 10 ppm benzene for 6 h/d X 5 d. Immediately after the last exposure, mice were injected, i.v., with either saline or hydroxyurea (HU). The dose of HU was sufficient to kill hematopoietic cells in or near S-phase of the cell cycle and sufficient to synchronize the surviving populations of hematopoietic cells. Three days after benzene exposure, CFU-E numbers had declined to 50% of control values while CFU-GM numbers were equal to control values at this time. The benzene exposures were sufficient to double the percentage of CFU-E in S-phase but produced no such increase among CFU-Gm. During 3 days of recovery from benzene exposure and HU treatment, the CFU-E population expanded 30-fold while the CFU-GM population expanded less than 3-fold. Following benzene exposure and HU treatment, both progenitor cells produced elevated numbers of their respective progeny. When CFU-E from benzene-exposed mice were cultured with varying concentrations of erythropoietin (EPO), the response at maximal EPO concentration was 66% of the response by control CFU-E. This strongly suggests that the CFU-E populations from benzene-exposed mice had been depleted of cells in or near S-phase. The results indicate that CFU-GM respond to low-level benzene exposure by increasing their rate of differentiation but not their rate of proliferation, while CFU-E respond by increasing both their rates of differentiation and proliferation. We speculate that it is the increase in CFU-E proliferation that renders these cells more susceptible to benzene than their granulocytic counterparts, especially those CFU-E at or near the S-phase of the cell cycle. (orig.).

Dempster, A.M.; Snyder, C.A. (New York Univ. Medical Center, NY (United States). Inst. of Environmental Medicine)

1991-09-01

308

Factors affecting plasma prolactin concentrations throughout gestation in high producing dairy cows.  

Science.gov (United States)

The aim of the present study was to investigate possible relationships between plasma concentrations of prolactin and the following factors throughout gestation in lactating dairy cows: photoperiod, season, milk production, Neospora caninum-seropositivity, twin pregnancy, and plasma concentrations of pregnancy associated glycoproteins-1 (PAG-1), progesterone and cortisol. Pregnancy was diagnosed by trans-rectal ultrasonography on Day 40 post-insemination and by palpation per rectum on Days 90, 120, 150, 180 and 210 or until abortion in aborting cows. Blood samples were collected from each animal immediately before each pregnancy diagnosis. The study population was comprised of 73 non-aborting (54 Neospora-seropositive cows) and 20 aborting cows (all Neospora-seropositive) cows. In non-aborting cows, GLM repeated measures of analysis of variance revealed that lactation number and days in milk had no effect on plasma prolactin concentrations throughout gestation, whereas high plasma prolactin concentrations were significantly associated with high plasma levels of cortisol and PAG-1, with Neospora-seropositivity, positive photoperiod (increasing day length), twin pregnancy, and with low plasma progesterone concentrations. An interaction among plasma prolactin, plasma cortisol and milk production was observed in that plasma prolactin concentrations differed significantly throughout gestation and were highest in high-producing cows with high cortisol levels. In Neospora-seropositive non-aborting versus aborting cows, mean prolactin concentrations failed to differ on Days 40, 90, 120, 150 and 180 of pregnancy, whereas prolactin values were significantly lower (P=0.03) in aborting animals on Day 210 of pregnancy. Our results indicate that a positive photoperiod and Neospora-infection lead to increased plasma prolactin concentrations throughout gestation. Reduced prolactin concentrations detected in Neospora-seropositive aborting cows compared to non-aborting animals suggests a protective effect of prolactin in N. caninum infection. PMID:19036554

García-Ispierto, I; López-Gatius, F; Almería, S; Yániz, J; Santolaria, P; Serrano, B; Bech-Sàbat, G; Nogareda, C; Sulon, J; de Sousa, N M; Beckers, J F

2009-02-01

309

High-performance Kohler concentrators with uniform irradiance on solar cell  

Science.gov (United States)

A new free-form XR Kohler concentrator is presented that combines high geometric concentration, high acceptance angle and high irradiance uniformity on the solar cell. This is achieved by modifying the optical surfaces to produce Kohler integration. Although the new optical surfaces (that is, the ones including Kohler integration) behave optically quite different from the ones that do not integrate, but from the macroscopic point of view they are very similar to them. This means that they can be manufactured with the same techniques (typically plastic injection molding or glass molding) and that their production cost is the same i.e., with a high potential for low cost and high optical efficiency. The present approach is completely new and allows keeping the acceptance angle at high values and the concentration factor without increasing the number of optical elements. The simulated optical performance of a Kohler integrating solar concentrator is presented. This concept is the first design combining non flat array of Kohler integrators with concentration optics.

Hernández, M.; Cvetkovic, A.; Benítez, P.; Miñano, J. C.

2008-08-01

310

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

Science.gov (United States)

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

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

2013-01-01

311

Phenylacetylene reversibly inhibits the phenol hydroxylase of Pseudomonas sp. CF600 at high concentrations but is oxidized at lower concentrations.  

Science.gov (United States)

Alkynes are mechanism-based inhibitors of several bacterial monooxygenases, including the soluble methane monooxygenase (sMMO) of Methylococcus capsulatus and the toluene o-monooxygenase (TOM) of Burkholderia cepacia G4. In this paper, we investigated the inhibition of the phenol hydroxylase of Pseudomonas sp. CF600 by the alkyne phenylacetylene. Growth of CF600 on phenol and phenol hydroxylase activity were inhibited by phenylacetylene concentrations greater than 1.0 mM. Unlike other alkynes, which irreversibly inhibit a number of monooxygenases, inhibition of phenol hydroxylase by phenylacetylene was reversible, as demonstrated by the ability of washed cells to regain phenol hydroxylase activity. Additionally, phenylacetylene was metabolized by phenol-grown cells, yielding a yellow meta-ring fission product which absorbed light maximally at 412 nm. Phenol-grown CF600 transformed phenylacetylene to hydroxyphenylacetylene and 2-hydroxy-6-oxo-octa-2,4-dien-7-ynoic acid as detected by gas chromatography--mass spectroscopy and high-performance liquid chromatography (HPLC), respectively, while neither a derivative of CF600 with a non-functional phenol hydroxylase nor wild-type CF600 grown on acetate transformed phenylacetylene. These results demonstrate that the phenol hydroxylase of CF600 has broader substrate specificity than previously reported. They also suggest that phenylacetylene acts as a competitive inhibitor rather than as a mechanism-based inhibitor of this phenol hydroxylase. PMID:16485115

Kagle, Jeanne; Hay, Anthony G

2006-09-01

312

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

313

High active carrier concentration in n-type, thin film Ge using delta-doping  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We demonstrate CVD in situ doping of Ge by utilizing phosphorus delta-doping for the creation of a high dopant diffusion source. Multiple monolayer delta doping creates source phosphorous concentrations above 1 × 10[superscript 20]cm[superscript ?3], and uniform activated dopant concentrations above 4 × 10[superscript 19]cm[superscript ?3] in a 600-800nm thick Ge layer after in-diffusion. By controlling dopant out-diffusion, near-complete incorporation of phosphorus diffusion source is ...

Cai, Yan; Bessette, Jonathan T.; Kimerling, Lionel C.; Michel, Jurgen; Camacho-aguilera, Rodolfo Ernesto

2012-01-01

314

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

Science.gov (United States)

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 <9% and <16% lower than U.S. Geological Survey's (USGS) estimates using their LOADEST or composite methods, respectively. USGS methods generally overestimated nitrate 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.

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

2014-11-01

315

Anti-benzene compounds. Conversion of benzene to toluene by methyl donors, in man.  

Science.gov (United States)

The level of benzene in blood can be efficiently reduced, an its noxious effect neutralized, by the concurrent administration of either of two groups of organic compounds: 1) methyl donors such as choline and betaine; and, 2) cysteine-HCL. Methionine acts as a precursor of cysteine in the body as uell as a methyl donor like choline and betaine. The appearance of toluene in blood was demonstrated after the sequential ingestion of choline plus betaine, benzene. The results are discussed in relation to clinical application in workers chronically exposed to benzene. PMID:594433

Braier, L

1977-01-01

316

An application of ultraviolet spectroscopy to study interactions in proteins solutions at high concentrations.  

Science.gov (United States)

Studies of protein-protein interactions (PPIs), especially in high-concentration solutions, have become increasingly important from a pharmaceutical perspective. Analytical methods used to study protein interactions, however, rely primarily on the detection of nonideality in relatively dilute (variable-pathlength ultraviolet (UV)-visible absorption spectroscopy to examine and better understand such interactions over a wide concentration range (5-240 mg/mL) using several representative proteins. In this study, the change in UV absorption (or extinction coefficient) was monitored by determining delta absorbance (?Abs), the difference between the measured absorbance and the corresponding theoretical absorbance (calculated from gravimetric dilution), over a wide range of protein concentrations. The ?Abs, corrected for light scattering, was found to increase with protein concentration for three model proteins (bovine serum albumin, lysozyme, and monoclonal antibody). Because PPIs influence solution viscosity, we studied the correlation between ?Abs measurements and viscosity as a function of protein concentration. The magnitude of ?Abs and solution viscosity followed similar trends with increasing protein concentration, albeit to different extents for different proteins. These data support the use of such ?Abs measurements as an alternative approach to monitor and evaluate interactions in protein solutions at high concentration. PMID:22581726

Thakkar, Santosh V; Allegre, Kevin M; Joshi, Sangeeta B; Volkin, David B; Middaugh, C Russell

2012-09-01

317

Diffusion of hydrogen and deuterium in Nb and Ta at high concentrations  

International Nuclear Information System (INIS)

The concentration dependence of the diffusion coefficient of H and D in Nb and Ta in the ? and ?' phases has been measured between 0 and 40% H or D/Nb or Ta by the Gorsky effect. Since this method allows to determine simultaneously the thermodynamic factor, the tracer-diffusion coefficient can be extracted from the data. An increase of the activation energy as a function of concentration has been found for all four systems. Whereas for Ta the isotope dependence of the diffusion coefficients continues to exist at high concentrations it surprisingly disappears for Nb. (orig.)

318

High Concentrating GaAs Cell Operation Using Optical Waveguide Solar Energy System  

Science.gov (United States)

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.

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

2004-01-01

319

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 ...

320

Application of Hydrothermal Treatment to High Concentrated Sewage Sludge for Anaerobic Digestion Process  

Directory of Open Access Journals (Sweden)

Full Text Available Tomato and seaweed were produced by utilizing CO2 and heat discharged from power generation using biogas in Toyogawa biomass park, Japan. The biogas was obtained by anaerobic digestion with hydrothermal treatment. The hydrothermal treatment was applied to the high concentrated sewage sludge (22 % total solids (TS dewatered sludge. The purpose of this study is to clarify the effect of hydrothermal treatment on the qualities of high concentrated sewage sludge, by analyzing particulate organic carbon (POC and dissolved organic carbon (DOC. The hydrothermal treatment was investigated under 10-60 min of treatment time, 180-200 °C of temperature, 10-22 %-TS of sewage sludge concentration. The results showed that the DOC in each conditions increased through hydrothermal treatment. The highest DOC obtained was 67 % of total carbon concentration, when the temperature was 180 °C, treatment time was 60 min and sewage sludge concentration was 10 %-TS. Furthermore, the viscosity of treated sewage sludge was decreased by hydrothermal treatment. In batch anaerobic digestion test, methane gas production was confirmed. In addition, this study evaluated the energy balance of this system. Thus, the results of this study indicated that the possibility of application of hydrothermal treatment to high concentrated sewage sludge for anaerobic digestion process. Keywords: anaerobic reaction, hydrothermal treatment, sewage sludge, solubilization

M. Orikawa

2013-10-01

 
 
 
 
321

Concentration of apolipoprotein-E in high-density lipoproteins of human blood plasma  

Directory of Open Access Journals (Sweden)

Full Text Available The aim of this study was to determine apolipoprotein (apo E concentration in the high-density lipoprotein (HDL fractions of normolipidemic subjects. ApoE concentrations in total blood plasma and HDL fractions were measured by an immunoturbidimetric method. We observed that the quantitative distribution of apoE among different lipoprotein classes depends on the total plasma apoE concentration: at low total plasma apoE concentration, a substantial amount of apoE was associated with HDL; an increase in total plasma apoE was accompanied by a more equal distribution of apoE among lipoprotein fractions. The concentration of apoE in the HDL fraction was stable and did not depend on the total plasma apoE concentration. Thus, the preservation of a constant concentration of apoE in HDL due to its redistribution among lipoprotein classes is a priority when total plasma apoE concentrations change. This feature should be considered at diagnosis and for the treatment of lipid disorders.

Kaneva Anastasiya M.

2013-01-01

322

Excitation of the luminescence of europium and curium in benzene solutions of methyltrioctylammonium thiocyanate  

International Nuclear Information System (INIS)

The emission spectra have been obtained, and the decay times have been measured, of the luminescence of europium and curium in benzene solutions of methyltrioctylammonium thiocyanate, at temperature of 77 and 293 K. It is inferred that in these solutions the elements tested exist in two forms which differ in the shape of the spectra and the decay times of the luminescence. It is shown that, because of the nonlinearity of the concentration dependence of the luminescence intensity of europium in benzene solutions of methyltrioctylammonium thiocyanate, it is advantageous to determine the content of europium in extracts in presence of thenoyltrifluoroacetone

323

Rheology Control of Highly Concentrated Mullite Suspensions with Polyelectrolyte for Robocasting  

Energy Technology Data Exchange (ETDEWEB)

Highly concentrated, aqueous mullite slurries were characterized and stabilized at solids concentrations as high as 60 vol% using less than 2 vol% of an organic polyelectrolyte dispersant. The maximum slurry concentration (60 vol%) is within 3 vol% of the maximum consolidated density of the slurry. The slurries were subsequently cast into parts by a solid freeform fabrication technique termed robocasting and characterized. Sedimentation analysis and viscometry provided the means of slurry characterization, while knowledge of polyelectrolyte and interparticle forces was used to interpret the sedimentation and viscometry data. Through proper control of slurry conditions, pseudoplastic mullite slurries were fabricated for use in the robocasting process. The slurries were robocast at 52 vol% solids and subsequently yielded a green density of 55 vol%. Fired densities of the robocasted slurries were high, with mullite >96% dense at 1,650 C.

STUECKER,JOHN N.; CESARANO III,JOSEPH; HIRSCHFELD,DEIDRE A.

2000-06-12

324

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

325

Effect of highly concentrated salt on retention of organic solutes by nanofiltration polymeric membranes  

DEFF Research Database (Denmark)

During desalination of feed with highly concentrated salt by nanofiltration (NF), predictive modeling was difficult due to the effect of salt on retention of organic solutes. Consequently, a better understanding of salt effect on membrane and organic solutes was required. In this study, four well-known commercially available NF polymeric membranes, NF270, NF-, Desal-5 DL and Nanomax50, were analyzed by a model based on an extended Nernst–Planck equation, using highly concentrated glucose and sodium chloride (NaCl) solutions. The results showed that with increasing salt concentration, the solute-to-pore size ratio (?i) decreased while the ratio of effective membrane thickness to porosity (?x/?) increased, indicating that the effect of salt may include decreasing solutes size, increasing membrane pore size, and increasing effective membrane thickness. Moreover, such salt effect appeared to be independent of membrane and solute types, and the correction model could well predict the retention of charged solutes at high salt concentration because electrostatic repulsion effect between charged solutes and membranes was completely screened by the salt ions. Meanwhile, several hypotheses such as membrane swelling, hydration layer thinning and particle collision were provided to explain the change of model parameters by highly concentrated salt.

Luo, Jianquan; Wan, Yinhua

2011-01-01

326

Exploration of the horizontally staggered light guides for high concentration CPV applications.  

Science.gov (United States)

The material and processing costs are still the major drawbacks of the c-Si based photovoltaic (PV) technology. The wafer cost comprises up to 35-40% of the total module cost. New approaches and system designs are needed in order to reduce the share of the wafer cost in photovoltaic energy systems. Here we explore the horizontally staggered light guide solar optics for use in Concentrated Photovoltaic (CPV) applications. This optical system comprises a lens array system coupled to a horizontal light guide which directs the incoming light beam to its edge. We have designed and simulated this system using a commercial ray tracing software (Zemax). The system is more compact, thinner and more robust compared to the conventional CPV systems. Concentration levels as high as 1000x can easily be reached when the system is properly designed. With such a high concentration level, a good acceptance angle of + -1 degree is still be conserved. The analysis of the system reveals that the total optical efficiency of the system could be as high as %94.4 without any anti-reflection (AR) coating. Optical losses can be reduced by just accommodating a single layer AR coating on the initial lens array leading to a %96.5 optical efficiency. Thermal behavior of high concentration linear concentrator is also discussed and compared with a conventional point focus CPV system. PMID:23038554

Selimoglu, Ozgur; Turan, Rasit

2012-08-13

327

Acute suppression of serum IgM and IgA in tank workers exposed to benzene.  

Science.gov (United States)

We investigated associations between benzene exposure and alterations of proteins and cells of the immune system among workers maintaining cargo tanks containing crude oil residues. Individual exposure to benzene, benzene in blood and urine, peripheral blood lymphocytes (total lymphocytes, lymphocytes in subpopulations CD3, CD4, CD8, CD19, CD56 and CD4/CD8 ratio), complement factors C3 and C4 and serum concentration of immunoglobulins (IgG, IgA, IgM and IgE) were analysed among 13 tank workers and nine unexposed referents (catering section). Benzene exposure was measured during three consecutive 12-h work days. Blood and urine samples were collected pre-shift on the first day (baseline), post-shift on the third day, and pre-next shift on the following morning. The time spent in the cargo tank was logged. The individual geometric mean benzene exposure in the breathing zone of tank workers over 3 days was 0.15 p.p.m. (range 0.01-0.62 p.p.m.) (n = 26). The geometric mean benzene concentration in blood post-shift was 12.3 nmol/l among tank workers versus 0.7 nmol/l among the referents. Tank workers showed a decline (versus referents) in IgM from baseline to post-shift (t-test, P = 0.04) and IgA from baseline to pre-next shift (t-test, P = 0.01). They also showed a decline in CD4 T cells from baseline to post-shift (t-test, P = 0.04). Suppression correlated with benzene exposure, benzene concentrations in blood and urine and time spent in the tank. The groups did not differ significantly in the change in other immune parameters. The clinical significance is unknown and warrants further studies. PMID:17083627

Kirkeleit, J; Ulvestad, E; Riise, T; Bråtveit, M; Moen, B E

2006-12-01

328

High concentration preferential adsorption of zinc acetate onto acid treated activated carbon for impregnation purposes  

International Nuclear Information System (INIS)

Impregnation of activated carbon has long been the subject of researchers working in the area of protection against air pollutants, especially those interested in making personal protective equipments. People who are involved in research of heavy metal removal using activated carbon have worked at very low concentrations. Moreover, the literature available in the open domain does not reveal the secrets of working at high concentration i.e., greater than 1 mM. Working at higher salt concentrations is necessary for the purpose of impregnating the activated carbon to a certain level with metals like copper, zinc, silver, chromium, tungsten, molybdenum etc. Activated carbon impregnated with these metals can be very effective in the removal of certain toxic gases. A locally available microporous activated carbon GAC89 was pretreated with nitric acid. B.E.T. surface areas and Boehm titrations were done. A large range of concentrations of aqueous solution of zinc acetate which is a preferentially adsorbing salt was made and stirred with the raw AC and the pretreated AC. Atomic absorption spectroscopy was employed to determine the amount of zinc acetate actually adsorbed onto the carbon sample. The results were fitted to a sum of two distinct adsorption isotherms, one for low concentrations i.e., less than 1 mM, and the other for high concentrations. The lower concentration adsorption is largely influenced by the solution pH. It is observed that at higher concentrations, the served that at higher concentrations, the adsorption is weaker and the underlying mechanism is under study. (author)

329

THE INFLUENCE OF BENZENE AS A TRACE REACTANT IN TITAN AEROSOL ANALOGS  

International Nuclear Information System (INIS)

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 C6H6/CH4/N2 via far ultraviolet irradiation (120-200 nm). The compositional results are compared to those from aerosol generated by a more ''traditional Titan'' mixture of CH4/N2. Our results show that even a trace amount of C6H6 (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 CH4, 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.

330

THE INFLUENCE OF BENZENE AS A TRACE REACTANT IN TITAN AEROSOL ANALOGS  

Energy Technology Data Exchange (ETDEWEB)

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.

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

331

The Influence of Benzene as a Trace Reactant in Titan Aerosol Analogs  

Science.gov (United States)

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 C6H6/CH4/N2 via far ultraviolet irradiation (120-200 nm). The compositional results are compared to those from aerosol generated by a more "traditional Titan" mixture of CH4/N2. Our results show that even a trace amount of C6H6 (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 CH4, 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.

Trainer, Melissa G.; Sebree, Joshua A.; Yoon, Y. Heidi; Tolbert, Margaret A.

2013-03-01

332

Rotating biological contactor reactor with biofilm promoting mats for treatment of benzene and xylene containing wastewater.  

Science.gov (United States)

A novel rotating biological contactor (RBC) bioreactor immobilized with microorganisms was designed to remove volatile organic compounds (VOC), such as benzene and xylene from emissions, and its performance was investigated. Gas-phase VOCs stripped by air injection were 98 % removed in the RBC when the superficial air flow rate was 375 ml/h (1,193 and 1,226 mg/l of benzene and xylene, respectively). The maximum removal rate was observed to be 1,007 and 1,872 mg/m(3)/day for benzene and xylene, respectively. The concentration profile of benzene and xylene along the RBC was dependent on the air flow rate and the degree of microbial adaptation. Air flow rate and residence time were found to be the most important operational parameters for the RBC reactor. By manipulating these operational parameters, the removal efficiency and capacity of the bioreactor could be enhanced. The kinetic constant K (s) demonstrated a linear relationship that indicated the maximum removal of benzene and xylene in RBC reactor. The phylogenic profile shows the presence of bacterium like Pseudomonas sp., Bacillus sp., and Enterococcus sp., which belonged to the phylum Firmicutes, and Proteobacteria that were responsible for the 98 % organic removal in the RBC. PMID:23076564

Sarayu, K; Sandhya, S

2012-12-01

333

Low level detection of Benzene in Food Grade Hexane by Ultraviolet Spectrophotometry.  

Science.gov (United States)

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

Emmandi, R; Sastry, M I S; Patel, M B

2014-10-15

334

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)

335

Tuning electronic eigenvalues of benzene via doping  

Science.gov (United States)

Using variable atomic numbers within molecular grand-canonical ensemble theory, the highest occupied Kohn-Sham eigenvalue of isoelectronic benzene derivatives is tuned. The performed transmutational changes correspond to the iterative doping with boron and nitrogen. The molecular Fukui function proves to be a reliable index in order to predict the changes in the highest occupied molecular orbital eigenvalue due to doping.

Marcon, Valentina; von Lilienfeld, O. Anatole; Andrienko, Denis

2007-08-01

336

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...with an end-of-service-life indicator for benzene, such...indicator shows no further useful life. (3) Respirator selection...air-purifying respirators, and a chin-style canister with full facepiece...respirators have a minimum service life of four hours when tested...

2010-07-01

337

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...Employers shall obtain or develop...benzene. (3) Information and training...explain the information contained in...The name, social security number...The name and social security number...copy of the information provided to...Extinguishing Media: Carbon dioxide...decomposition products: Toxic...

2010-07-01

338

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...record shall include: (A) The name and social security number of the employee; ...document that benzene is present in the workplace less than 30 days a year, respirators...Upper: 7.5% 4. Extinguishing Media: Carbon dioxide, dry chemical, or...

2010-07-01

339

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...there is an abnormal differential count. (ii...employee shall be reduced to the extent that...sampling and analytical methods used; (C) A...strictly standardized methods. 1. Red cell...white blood cell differential, hematacrit and...Sampling and Analytical Methods for Benzene...

2010-07-01

340

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...benzene vapor is of extreme importance. The hematopoietic...finding at one test time. The importance of trend highlights the need...granulocytes possess two round nuclear segements—less often one...efficiency. 5.5.1. Importance of determination. The...

2010-07-01

 
 
 
 
341

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...the corrective actions to be taken...minute (LPM), a temperature of 25 °C...or above the action level 30 or...new exposure to potential marrow toxins...Autoignition Temperature: 580 °C (1076...considered a potential fire explosion...The defatting action of benzene...

2010-07-01

342

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...those operations in which engineering controls or work practice...may be used in lieu of engineering controls. If respirators...controlled. Use nonsparking tools when opening or closing...Use non-sparking tools to open benzene containers...be more rapid in the case of abraded skin,...

2010-07-01

343

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)

344

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...prolonged benzene exposure may be delayed for many months or years after...prepared from a specimen of venous blood which has been collected...progressed through a preliminary phase of hematologic abnormality...chromatograph are: 1. Mobile phase—Methyl alcohol/water,...

2010-07-01

345

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...be encountered are: the primary production and utilization of benzene...absorption tubes, with subsequent chemical analysis by gas chromatography. Sampling...validation studies was a Waters uBondapack C18, 30 cm...grade. 4.2. HPLC grade water, methyl alcohol, and...

2010-07-01

346

Potential risk of mitomycin C at high concentrations on peripheral nerve structure.  

Science.gov (United States)

Although the local application of mitomycin C may prevent epidural adhesion after laminectomy, mitomycin C can induce neurotoxicity in optic and acoustic nerves at high concentrations. To determine the safe concentration range for mitomycin C, cotton pads soaked with mitomycin C at different concentrations (0.1, 0.3, 0.5, and 0.7 mg/mL) were immediately applied for 5 minutes to the operation area of rats that had undergone laminectomy at L1. Rat sciatic nerves, instead of dorsal nerves, were used in this study. The results showed that mitomycin C at 0.1-0.5 mg/mL did not damage the structure and function of the sciatic nerve, while at 0.7 mg/mL, mitomycin C significantly reduced the thickness of the sciatic nerve myelin sheath compared with lower concentrations, though no functional change was found. These experimental findings indicate that the local application of mitomycin C at low concentrations is safe to prevent scar adhesion following laminectomy, but that mitomycin C at high concentrations (> 0.7 mg/mL) has potential safety risks to peripheral nerve structures. PMID:25206895

Sui, Tao; Zhang, Jinhong; Du, Shihao; Su, Changhui; Que, Jun; Cao, Xiaojian

2014-04-15

347

Vitamin E Concentrations in Adults with HIV/AIDS on Highly Active Antiretroviral Therapy  

Science.gov (United States)

HIV/AIDS patients are probably more predisposed to vitamin E deficiency, considering that they are more exposed to oxidative stress. Additionally, there are an extensive number of drugs in the highly active antiretroviral therapy (HAART) regimens that may interfere with vitamin E concentrations. The objective of this study was to compare serum concentrations of alpha-tocopherol in 182 HIV/AIDS patients receiving different HAART regimens. The patients were divided into three groups according to regimen: nucleoside analog reverse-transcriptase inhibitors (NRTIs) + non-nucleoside analog reverse-transcriptase inhibitors (NNRTIs); NRTIs + protease inhibitors + ritonavir; NRTIs + other classes. Alpha-tocopherol was assessed by high-performance liquid chromatography. Multiple linear regression analysis was used to evaluate the effects of HAART regimen, time of use, and compliance with the regimen on alpha-tocopherol concentrations. Alpha-tocopherol concentrations were on average 4.12 ?mol/L lower for the NRTIs + other classes regimen when compared to the NRTIs + NNRTIs regimen (p = 0.037). A positive association (p < 0.001) was observed between alpha-tocopherol and cholesterol concentrations, a finding due, in part, to the relationship between liposoluble vitamins and lipid profile. This study demonstrated differences in alpha-tocopherol concentrations between patients using different HAART regimens, especially regimens involving the use of new drugs. Long-term prospective cohort studies are needed to monitor vitamin E status in HIV/AIDS patients since the beginning of treatment. PMID:25225815

Kaio, Daniella J. Itinoseki; Rondo, Patricia Helen C.; Luzia, Liania Alves; Souza, Jose Maria P.; Firmino, Aline Vale; Santos, Sigrid Sousa

2014-01-01

348

Vitamin E Concentrations in Adults with HIV/AIDS on Highly Active Antiretroviral Therapy  

Directory of Open Access Journals (Sweden)

Full Text Available HIV/AIDS patients are probably more predisposed to vitamin E deficiency, considering that they are more exposed to oxidative stress. Additionally, there are an extensive number of drugs in the highly active antiretroviral therapy (HAART regimens that may interfere with vitamin E concentrations. The objective of this study was to compare serum concentrations of alpha-tocopherol in 182 HIV/AIDS patients receiving different HAART regimens. The patients were divided into three groups according to regimen: nucleoside analog reverse-transcriptase inhibitors (NRTIs + non-nucleoside analog reverse-transcriptase inhibitors (NNRTIs; NRTIs + protease inhibitors + ritonavir; NRTIs + other classes. Alpha-tocopherol was assessed by high-performance liquid chromatography. Multiple linear regression analysis was used to evaluate the effects of HAART regimen, time of use, and compliance with the regimen on alpha-tocopherol concentrations. Alpha-tocopherol concentrations were on average 4.12 ?mol/L lower for the NRTIs + other classes regimen when compared to the NRTIs + NNRTIs regimen (p = 0.037. A positive association (p < 0.001 was observed between alpha-tocopherol and cholesterol concentrations, a finding due, in part, to the relationship between liposoluble vitamins and lipid profile. This study demonstrated differences in alpha-tocopherol concentrations between patients using different HAART regimens, especially regimens involving the use of new drugs. Long-term prospective cohort studies are needed to monitor vitamin E status in HIV/AIDS patients since the beginning of treatment.

Daniella J. Itinoseki Kaio

2014-09-01

349

High-concentration zeta potential measurements using light-scattering techniques.  

Science.gov (United States)

Zeta potential is the key parameter that controls electrostatic interactions in particle dispersions. Laser Doppler electrophoresis is an accepted method for the measurement of particle electrophoretic mobility and hence zeta potential of dispersions of colloidal size materials. Traditionally, samples measured by this technique have to be optically transparent. Therefore, depending upon the size and optical properties of the particles, many samples will be too concentrated and will require dilution. The ability to measure samples at or close to their neat concentration would be desirable as it would minimize any changes in the zeta potential of the sample owing to dilution. However, the ability to measure turbid samples using light-scattering techniques presents a number of challenges. This paper discusses electrophoretic mobility measurements made on turbid samples at high concentration using a novel cell with reduced path length. Results are presented on two different sample types, titanium dioxide and a polyurethane dispersion, as a function of sample concentration. For both of the sample types studied, the electrophoretic mobility results show a gradual decrease as the sample concentration increases and the possible reasons for these observations are discussed. Further, a comparison of the data against theoretical models is presented and discussed. Conclusions and recommendations are made from the zeta potential values obtained at high concentrations. PMID:20732896

Kaszuba, Michael; Corbett, Jason; Watson, Fraser Mcneil; Jones, Andrew

2010-09-28

350

Characterization of high-milk-protein powders upon rehydration under various salt concentrations.  

Science.gov (United States)

Rehydration of native micellar casein and native whey isolate protein powders was followed in different ionic environments. Solutions of NaCl and CaCl2 in the concentration range of 0 to 12% (wt%) were used as rehydration media. The rehydration profiles obtained were interpreted in terms of wetting, swelling, and dispersion stages by using a turbidity method. Two behaviors were observed depending on the salt concentration. For native micellar casein powder, a significant change was observed between 3 and 6% NaCl and between 0.75 and 1.5% CaCl2. The first behavior (low salt concentration) presents a typical rehydration profile: quick wetting, swelling, and long dispersion stage. The dispersion stage of the second behavior (high salt concentration) was significantly shortened, indicating a strong modification of the protein backbone. The rehydration of whey protein powder was less influenced by salts. At low salt concentrations, a typical profile for whey powders was observed: wetting with lump formation and no swelling followed by a quick dispersion. At high CaCl2 concentrations, no turbidity stabilization was observed, indicating a possible protein unfolding and denaturation. Additionally, the changes in secondary structures of the 2 proteins upon salt increase were followed by Fourier transform infrared spectroscopy and confirmed the different profiles observed. PMID:21183012

Hussain, R; Gaiani, C; Aberkane, L; Scher, J

2011-01-01

351

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)

352

Antagonistic effects between magnetite nanoparticles and a hydrophobic surfactant in highly concentrated Pickering emulsions.  

Science.gov (United States)

Herein we present a systematic study of the antagonistic interaction between magnetite nanoparticles (Fe3O4) and nonionic hydrophobic surfactant in Pickering highly concentrated emulsions. Interfacial tension measurements, phase behavior, and emulsion stability studies, combined with electron microscopy observations in polymerized systems and magnetometry, are used to support the discussion. First, stable W/O highly concentrated emulsions were obtained using partially hydrophobized magnetite nanoparticles. These emulsions experienced phase separation when surfactant is added at concentrations as low as 0.05 wt %. Such phase separation arises from the preferential affinity of the surfactant for the nanoparticle surfaces, which remarkably enhances their hydrophobicity, leading to a gradual desorption of nanoparticles from the interface. W/O emulsions were obtained at higher surfactant concentrations, but in this case, these emulsions were mainly stabilized by surfactant molecules. Therefore, stable emulsions could be prepared in two separate ranges of surfactant concentrations. After polymerization, low-density macroporous polymers were obtained, and the adsorption and aggregation of nanoparticles was analyzed by transmission electron microscopy. The progressive displacement of the nanoparticles was revealed: from the oil-water interface, in which aggregated nanoparticles were adsorbed, forming dense layers, to the continuous phase of the emulsions, where small nanoparticle aggregates were randomly dispersed. Interestingly, the results also show that the blocking temperature of the iron oxide superparamagnetic nanoparticles embedded in the macroporous polymers could be modulated by appropriate control of the concentrations of both surfactant and nanoparticles. PMID:24738961

Vílchez, Alejandro; Rodríguez-Abreu, Carlos; Menner, Angelika; Bismarck, Alexander; Esquena, Jordi

2014-05-13

353

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)

354

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

DEFF Research Database (Denmark)

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.

Glud, Ronnie N.; Larsen, Morten

2013-01-01

355

46 CFR 197.565 - Notifying personnel of benzene hazards.  

Science.gov (United States)

...sheet. A material safety data sheet (MSDS) addressing benzene must be made available...involved in the benzene operation. The MSDS must describe the physical and chemical...appendices A and B of this subpart or a MSDS on benzene meeting the requirements...

2010-10-01

356

High Frequency Measurements of Methane Concentrations and Carbon Isotopes at a Marsh and Landfill  

Science.gov (United States)

High frequency measurements of methane concentrations and carbon isotopes can help constrain the source strengths of methane emitted to the atmosphere. We report here methane concentrations and 13C values measured at 0.5 Hz with cavity enhanced laser absorption spectrometers (Los Gatos Research) deployed at a saltmarsh in Alabama and a landfill in Florida. Methane concentrations and 13C at the saltmarsh were monitored over a 2.5 day time period at 2 m, 0.5 m above the ground as well as from the outflow of a flow-through (2 L) chamber placed on the Spartina alterniflora dominated marsh. A typical measurement cycle included regular samples from two tanks of known methane concentrations and isotopic values and from ambient air samples. Over the 2.5-day measurement period methane concentrations and isotopic ratios at 2 m averaged 1.85 ppm and -43.57‰ (±0.34, 1 SE), respectively. The concentration and isotopic values from the chamber outflow varied from 1.92 to 5.81 ppm and -38.5 to -59.3‰, respectively. Methane flux from the marsh ranged from undetectable to 3.6 mgC m-2hr-1, with high fluxes measured during low tide. The 13?CH4 of the emitted CH4 from the marsh, determined from a mass balance equation using the chamber inflow and outflow concentration and isotopic values ranged from -62.1 to -93.9‰ and averaged -77‰ (±1.25, 1SE). At the landfill ambient methane concentrations and 13C ratios measured over multiple days varied from 4.25 to 11.91 ppm and from -58.81 to -45.12‰, respectively. At higher methane concentrations the ?13C of CH4 was more depleted consistent with previously observed relationship at this site made by more traditional techniques. Over a 30-minute measurement period CH4 concentrations at the landfill could vary by as much as 15 ppm. The high frequency continuous optical measurements with field-deployed instruments provide us with an unprecedented temporal resolution of CH4 concentrations and isotopic ratios. These measurements will enable us to determine the magnitude and to identify the sources of emission at local to regional scales.

Mortazavi, B.; Wilson, B.; Chanton, J.; Eller, K.; Dong, F.; Baer, D. S.; Gupta, M.; Dzwonkowski, B.

2012-12-01

357

Highly concentrated aqueous suspensions of graphene through ultrasonic exfoliation with continuous surfactant addition.  

Science.gov (United States)

Highly concentrated suspensions of graphene stabilized with surfactant were prepared using ultrasonic exfoliation. Concentrations of up to 1.5% w/w (15 mg/mL) were achieved through the continuous addition of the surfactant during the exfoliation process. Previous methods typically add the surfactant only once, prior to the commencement of sonication. The vast increase in the available solid-liquid interfacial area through delamination results in the rapid depletion of the surfactant from solution through adsorption. This leads to a change in the liquid-vapor surface tension outside of the optimum range for the efficient production of graphene sheets. By continuously replacing the surfactant to lower the surface tension during sonication and the production of the graphene surface area, the concentration of particles was significantly increased. Cationic, anionic, and nonionic surfactants were studied and all showed significant increases in the concentration of graphene produced using this continuous addition method. PMID:22985170

Notley, Shannon M

2012-10-01

358

Simple and rapid determination of serum carbapenem concentrations by high-performance liquid chromatography.  

Science.gov (United States)

Although several high-performance liquid chromatography (HPLC) methods for the determination of serum concentrations of carbapenems have been reported, they are complicated and involve column switching. We established a simple and rapid HPLC method for the determination of serum concentrations of carbapenems, and this method is suitable for routine use in the clinical field. With our HPLC method, the serum concentrations of five commercially available carbapenems could be determined by changing only the methanol/phosphate-buffer ratio in the mobile phase. Serum levels of imipenem, panipenem, and meropenem in mice could be monitored when these carbapenems (20 mg/kg) were administered subcutaneously with cilastatin (20 mg/kg). These results suggest that our simple and rapid HPLC method for the determination of the serum concentrations of carbapenems is useful for pharmacokinetic/pharmacodynamic (PK/PD)-based determination of carbapenem dosage regimens. PMID:18297446

Kurihara, Yuji; Kizu, Junko; Hori, Seiji

2008-02-01

359

Occupational exposure of water-plant operators to high concentrations of radon-222 gas.  

Science.gov (United States)

Water-plant operators may be exposed to high airborne radon-222 (222Rn) concentrations created when 222Rn gas transfers from water to air during the water treatment processes. To evaluate this hazard, we placed yearlong alpha-track radon detectors in 31 water plants. The geometric mean of the annual average airborne 222Rn concentrations was 3.4 pCi L-1 (126 Bq m-3), with a maximum of 133 pCi L-1 (4921 Bq m-3). We assessed the short-term temporal variability of 222Rn by monitoring four water plants continuously for a 3- to 6-day period. Cumulative working level months were estimated for the time workers were in the water plants. Because airborne 222Rn concentrations in water plants can reach levels considered unsafe for underground miners, it would be prudent to monitor airborne 222Rn concentrations in water plants which aerate water as part of their treatment process. PMID:8863200

Fisher, E L; Fuortes, L J; Field, R W

1996-08-01

360

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

Energy Technology Data Exchange (ETDEWEB)

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)

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

 
 
 
 
361

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

Science.gov (United States)

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%.

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

362

Investigating DOC export dynamics using high-frequency instream concentration measurements  

Science.gov (United States)

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.

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

2014-05-01

363

Different behavior of water in confined solutions of high and low solute concentrations.  

Science.gov (United States)

Water-glycerol solutions confined in 21 Å pores of the silica matrix MCM-41 C10 have been studied using differential scanning calorimetry (DSC) and broadband dielectric spectroscopy (BDS). The results suggest a micro-phase separation caused by the confinement. Likely the water molecules coordinate to the hydroxyl surface groups of the pores, leaving most of the glycerol molecules in the centre of the pores. This makes the dynamics of glycerol almost concentration independent up to water concentrations of about 85 wt%. However, at higher water concentrations no substantial clustering of glycerol molecules should occur and the glass transition related dynamics exhibit an anomalous behaviour. Instead of a common plasticization effect of water, as for the corresponding bulk solutions (when no ice is formed), it is evident that water acts as an anti-plasticizer in the confinement at high water concentrations. We propose that the increased water concentration slows down the glass transition related dynamics in the deeply supercooled regime due to that a rigid hydrogen bonded network structure of water molecules is formed at low temperatures and low glycerol concentrations. This is in contrast to the situation in a homogenously mixed bulk solution of a high solute concentration where the water molecules will be less hydrogen bonded, and therefore are typically more mobile than the surrounding solute molecules. An almost complete hydrogen bonded network of water molecules may, even in confinements, be sufficiently rigid to slow down the relaxation of embedded solute molecules. It can also be expressed the other way around, i.e. small amounts of glycerol act as a plasticizer for water, due to its breaking up of the nearly tetrahedral network structure. From the here observed concentration dependent behaviour of the deeply supercooled bulk and confined solutions it seems, furthermore, evident that the Tg value of bulk water cannot be estimated from extrapolations of aqueous solutions. PMID:23877276

Elamin, Khalid; Jansson, Helén; Kittaka, Shigeharu; Swenson, Jan

2013-11-14

364

Effects of high temperature stress at different development stages on soybean isoflavone and tocopherol concentrations.  

Science.gov (United States)

Soybean contains a range of compounds with putative health benefits including isoflavones and tocopherols. A study was conducted to determine the effects on these compounds of high temperature stress imposed at specific development stages [i.e., none, pre-emergence, vegetative, early reproductive (R1-4), late-reproductive (R5-8), or all stages]. Two cultivars (AC Proteina and OAC Champion) were grown in growth chambers set at contrasting temperatures [i.e., stress conditions of 33/25 °C (day/night temperature) and control conditions of 23/15 °C] in order to generate these treatments. Isoflavone and tocopherol concentrations in mature seeds were determined using high-performance liquid chromatography. In both cultivars isoflavone response was greatest when stress occurred during the R5-8 stages and during all development stages, these treatments reducing total isoflavone concentration by an average of 85% compared to the control. Stress imposed at other stages also affected isoflavone concentration although the response was smaller. For example, stress during the vegetative stages reduced total isoflavones by 33% in OAC Champion. Stress imposed pre-emergence had an opposite effect increasing daidzein concentration by 24% in AC Proteina. Tocopherol concentrations were affected the most when stress was imposed during all stages of development, followed by stress restricted to stages R5-8; response to stress during other stages was limited. The specific response of tocopherols differed, ?-tocopherol being increased by high temperature by as much as 752%, the reverse being observed for ?-tocopherol and ?-tocopherol. The present study demonstrates that while isoflavone and tocopherol concentrations in soybeans are affected the most by stress occurring during seed formation, concentrations can also be affected by stress occurring at other stages including stages as early as pre-emergence. PMID:22098462

Chennupati, Pratyusha; Seguin, Philippe; Liu, Wucheng

2011-12-28

365

High-sensitive concentration analysis of biochemical liquids using a microfluidic chip fabricated by femtosecond laser  

Science.gov (United States)

We demonstrate fabrication of microfluidic chips integrated with optical waveguide embedded in a photostructurable glass for high-sensitive biochemical liquid analysis using a femtosecond laser. Femtosecond laser direct writing followed by annealing and successive wet etching in hydrofluoric acid solution resulted in the rapid manufacturing of microfluidic chips for the biochemical liquid concentration assay. By covering the internal wall of the microfluidic channel in the glass with low refractive index polymer, interaction between the liquid and incident analyzing light is enhanced. Therefore, the microfluidic chip enables us to analyze the low concentrations down to 7.5 mM of protein in bovine serum albumin. Such microfluidic chip realizes the efficient and high-sensitive concentration analysis of biochemical liquids at early stages of biochemical reactions.

Hanada, Y.; Sugioka, K.; Midorikawa, K.

2012-03-01

366

Metal dynamics and tolerance of Typha domingensis exposed to high concentrations of Cr, Ni and Zn.  

Science.gov (United States)

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

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

2014-07-01

367

Self-assembling semicrystalline polymer into highly ordered, microscopic concentric rings by evaporation.  

Science.gov (United States)

A drop of semicrystalline polymer, poly(ethylene oxide) (PEO), solution was placed in a restricted geometry consisting of a sphere on a flat substrate (i.e., sphere-on-flat geometry). Upon solvent evaporation from the sphere-on-flat geometry, microscopic concentric rings of PEO with appropriate high molecular weight were produced via controlled, repetitive pinning ("stick") and depinning ("slip") cycles of the contact line. The evaporation-induced concentric rings of PEO exhibited a fibrillar-like surface morphology. Subsequent isothermal crystallization of rings at 40 and 58 degrees C led to the formation of multilayer of flat-on lamellae (i.e., spiral morphology). In between adjacent spirals, depletion zones were developed during crystallization, as revealed by AFM measurements. The present highly ordered, concentric PEO rings may serve as a platform to study cell adhesion and motility, neuron guidance, cell mechanotransduction, and other biological processes. PMID:18275235

Byun, Myunghwan; Hong, Suck Won; Zhu, Lei; Lin, Zhiqun

2008-04-01

368

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)

369

A SIMPLE WAY OF ACHIEVING A HIGH CELL CONCENTRATION IN RECOMBINANT Escherichia coli CULTIVATION  

Directory of Open Access Journals (Sweden)

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.

Gombert A.K.

1997-01-01

370

Rigor tension development in glycerinated rabbit psoas fibers at high salt concentrations.  

Science.gov (United States)

We attempted to measure the rigor tension development by glycerinated fibers of rabbit psoas at high salt concentrations such as 0.5 M KCl. The measurements were made feasible by covalently crosslinking the rod-portion of thick filaments in the fibers in the rigor state with a water-soluble carbodiimide (EDC) so that the thick filaments are not dissolved even at 0.5 M KCl. EDC crosslinks, though with much a slower rate, the myosin cross-bridge heads to the thin filaments. At high salt concentrations, the fibers developed no active tension but developed rigor tension when they were put into a rigor solution from a contracting or relaxing solution. Removal of only Mg++ from a MgATP-containing solution induced similar rigor tension development. The magnitude of the rigor tension was proportional to the fraction of the cross-bridge heads that were crosslinked to the thin filaments. The results suggest that the rigor tension at high salt concentrations is generated by structural changes in the cross-bridge heads that are crosslinked to the thin filaments, when these heads release MgATP or Mg++ (with ATP retained) from their active sites, but not generated by re-formation of the rigor complexes of uncrosslinked myosin heads with the thin filaments. Extrapolation to 100% crosslinked heads gave an estimate of the rigor tension development of more than 1 kg wt/cm2 at high salt concentrations. PMID:3407515

Tawada, K; Emoto, Y

1988-01-01

371

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

372

Interculturalism in Italian Primary Schools with a High Concentration of Immigrant Students  

Science.gov (United States)

The present article focuses on quantitative research carried out on a statistically representative sample of Italian primary schools with a high concentration of immigrant students. Research data show that schools with a higher number of immigrant students offer a greater number and a wider variety of intercultural initiatives. The presence of…

Catarci, Marco

2013-01-01

373

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

374

Hydrogen-terminated silicon nanowire photocatalysis: Benzene oxidation and methyl red decomposition  

Energy Technology Data Exchange (ETDEWEB)

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.

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

375

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.

376

Inhibition of pure cultures of methanogens by benzene ring compounds  

Energy Technology Data Exchange (ETDEWEB)

The inhibition of methane production by Methanosaeta concilii GP6, Methanospirillum hungatei GP1, Methanobacterium espanolae GP9, and Methanobacterium cryantii 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 (IC{sub 50}) was dependent on the species and the toxicant. Pentachlorophenol was the most toxic of the tested compounds, with an IC{sub 50} of less than 8 mg/liter for all species except M. hungatei. Abietic acid was the next most toxic compound for all the species, with an IC{sub 50} in the range of 21.4 to 203 mg/liter. Sodium benzoate was generally the least toxic, with an IC{sub 50} in the range of 1,225 to 32,400 mg/liter. 3-Chlorobenzoate was substantially more toxic (IC{sub 50}, 450 to 1,460 mg/liter) than benzoate. The inhibition by benzene, phenol, vanillic acid, and toluene was intermediate to that of pentachlorophenol and benzoate. Long-term incubation (days) studies to determine effect on growth indicated that all eight compounds were usually much more toxic than predicted from the short-term data. In these latter studies, there was generally a good correlation in the observed inhibition as determined from growth and methane production.

Patel, G.B.; Agnew, B.J.; Dicaire, C.J. (National Research Council of Canada, Ottawa, Ontario (Canada))

1991-10-01

377

Vitamin E concentrations in adults with HIV/AIDS on highly active antiretroviral therapy.  

Science.gov (United States)

HIV/AIDS patients are probably more predisposed to vitamin E deficiency, considering that they are more exposed to oxidative stress. Additionally, there are an extensive number of drugs in the highly active antiretroviral therapy (HAART) regimens that may interfere with vitamin E concentrations. The objective of this study was to compare serum concentrations of alpha-tocopherol in 182 HIV/AIDS patients receiving different HAART regimens. The patients were divided into three groups according to regimen: nucleoside analog reverse-transcriptase inhibitors (NRTIs) + non-nucleoside analog reverse-transcriptase inhibitors (NNRTIs); NRTIs + protease inhibitors + ritonavir; NRTIs + other classes. Alpha-tocopherol was assessed by high-performance liquid chromatography. Multiple linear regression analysis was used to evaluate the effects of HAART regimen, time of use, and compliance with the regimen on alpha-tocopherol concentrations. Alpha-tocopherol concentrations were on average 4.12 ?mol/L lower for the NRTIs + other classes regimen when compared to the NRTIs + NNRTIs regimen (p = 0.037). A positive association (p vitamins and lipid profile. This study demonstrated differences in alpha-tocopherol concentrations between patients using different HAART regimens, especially regimens involving the use of new drugs. Long-term prospective cohort studies are needed to monitor vitamin E status in HIV/AIDS patients since the beginning of treatment. PMID:25225815

Itinoseki Kaio, Daniella J Itinoseki; Rondó, Patricia Helen C; Luzia, Liania Alves; Souza, José Maria P; Firmino, Aline Vale; Santos, Sigrid Sousa

2014-09-01

378

Off-pathway aggregation can inhibit fibrillation at high protein concentrations  

DEFF Research Database (Denmark)

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.

Deva, Taru; Lorenzen, Nikolai

2013-01-01

379

Effects of high glucose and high insulin concentrations on osteoblast function in vitro.  

Science.gov (United States)

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 eff