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Concentrations and emissions of benzene  

Mar 13, 2008 ... Benzene emissions fell by 72 per cent between 1990 and 2007, and by 41 per ... \\and the main source of 1,3-butadiene is motor vehicle exhausts where 1 ... \\Internet Links: UK National Atmospheric Emissions Inventory (NAEI) ...

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Benzene vapor concentrations during a simulated crude oil spill  

International Nuclear Information System (INIS)

Benzene vapor concentrations during a simulated crude oil spill were measured to quantify the potential to exceed the Permissible Exposure Limits (PELs). The main concern was benzene vapor concentrations in worst-case situations. Vapors were measured using a variety of methods, including sample badge monitors, which are readily available for use by first responders. Worst-case conditions include rapid evaporation of high vapor pressure components (such as benzene) during the first hours of a spill; hot weather; enclosed areas; spreading surface area; and high API gravity crude oil (i.e., rich in high vapor pressure components). Under these conditions the time-weighted average benzene concentration exceeded 1 ppm during the first half hour of the simulation. Results several hours later, in open areas, or using lower API gravity crude oils were much lower. Calculated as an 8-hour average, exposures did not exceed the PEL of 1 ppm, although the 5 ppm short term exposure limit (STEL) was exceeded under the simulated wharf

1993-04-01

3

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

Science.gov (United States)

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

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Benzene from Traffic : Fuel Content and Ambient Air Concentrations  

DEFF Research Database (Denmark)

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

Palmgren, F.; Berkowicz, R.

2000-01-01

5

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

6

High pressure photoinduced ring opening of benzene  

International Nuclear Information System (INIS)

The chemical transformation of crystalline benzene into an amorphous solid (a-C:H) was induced at high pressure by employing laser light of suitable wavelengths. The reaction was forced to occur at 16 GPa, well below the pressure value (23 GPa) where the reaction normally occurs. Different laser sources were used to tune the pumping wavelength into the red wing of the first excited singlet state S1(1B2u) absorption edge. Here the benzene ring is distorted, presenting a greater flexibility which makes the molecule unstable at high pressure. The selective pumping of the S1 level, in addition to structural considerations, was of paramount importance to clarify the mechanism of the reaction

2002-02-25

7

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

8

An Order-of-Magnitude Estimation of Benzene Concentration in Saltstone Vault  

International Nuclear Information System (INIS)

The contents of Tank 48H that include the tetraphenylborate (TPB) precipitates of potassium and cesium will be grouted and stored in the Saltstone vault. The grouting process is exothermic, which should accelerate the rate of decomposition of TPB precipitates eventually to benzene. Because the vault is not currently outfitted with an active ventilation system, there is a concern that a mixture of flammable gases may form in the vapor space of each cell filled with the curing grout. The purpose of this study was to determine if passive breathing induced by the diurnal fluctuations of barometric pressure would provide any mitigating measure against potential flammability in the cell vapor space. In Revision 0 of this document, a set of algorithms were presented that would predict the equilibrium concentration of benzene in the cell vapor space as a function of benzene generation rate, fill height, and passive breathing rate. The algorithms were derived based on several simplifying assumptions so that order of magnitude estimates could be made quickly for scoping purposes. In particular, it was assumed that passive breathing would occur solely due to barometric pressure fluctuations that were sinusoidal; the resulting algorithm for estimating the rate of passive breathing into or out of each cell is given in Eq. (10). Since Revision 0 was issued, the validity of this critical assumption on the mode of passive breathing was checked against available passive ventilation data for the Hanford waste tanks. It was found that the passive breathing rates estimated from Eq. (10) were on average 50 to 90% lower than those measured for 5 out of 6 Hanford tanks considered in this study (see Table 1); for Tank U-106, the estimated passive breathing rates were on average 20% lower than the measured data. These results indicate that Eq. (10) would most likely under predict passive breathing rates of the Saltstone vault. At a given fill height and benzene generation rate, under predicted breathing rates would in turn make the benzene concentration projections in the cell vapor space conservatively high, thus rendering the overall flammability assessment conservative. The results of this validation effort are summarized in Section 2.4 of this revision. It is to be noted that all the algorithms, numerical results and conclusions made in Revision 0 remain valid. In this work, the algorithms for estimating the equilibrium benzene concentration for a given scenario were derived by combining the asymptotic solutions to the transient mass balance equations for the exhaling and inhaling modes in a 24-hour period. These algorithms were then applied to simulate several test cases, including the baseline case where the cell was filled to the maximum height of 25 ft at the bulk benzene generation rate of 3.4 g/hr

2006-01-01

9

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: 0.76-0.80, 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

2002-10-01

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Survey of benzene in foods by using headspace concentration techniques and capillary gas chromatography.  

Science.gov (United States)

Recently, the combination of sodium or potassium benzoate with ascorbic acid was shown to produce low levels (ng/g) of benzene in fruit-flavored soft drinks. The presence of benzene also was reported in butter, eggs, meat, and certain fruits; levels of these findings ranged from 0.5 ng/g in butter to 500-1900 ng/g in eggs. Because benzoates are widely used as food preservatives, a limited survey of other foods containing added benzoate salts was conducted to investigate the potential for benzene formation. Selected foods that did not contain added benzoates but were previously reported to contain benzene were analyzed for comparison. More than 50 foods were analyzed by purge-and-trap or static headspace concentration and capillary gas chromatography. Benzene was quantitated by using the method of standard additions, and its identity was confirmed by mass selective detection. Results of this limited survey show that foods without added benzoates (including eggs) contained benzene at levels equal to or less than 2 ng/g. Slightly higher levels were present in some foods and beverages containing both ascorbic acid and sodium benzoate. PMID:8286958

McNeal, T P; Nyman, P J; Diachenko, G W; Hollifield, H C

1993-01-01

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

1986-01-01

12

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

2011-12-01

13

Simultaneous Determination of Benzene and Toluene in Pesticide Emulsifiable Concentrate by Headspace GC-MS  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The toxic inert ingredients in pesticide formulations are strictly regulated in many countries. In this paper, a simple and efficient headspace-gas chromatography-mass spectrometry (HSGC-MS) method using fluorobenzene as an internal standard (IS) for rapid simultaneous determination of benzene and toluene in pesticide emulsifiable concentrate (EC) was established. The headspace and GC-MS conditions were investigated and developed. A nonpolar fused silica Rtx-5 capillary column (30?m × 0.20...

Cao, Lidong; Jiang, Hua; Yang, Jing; Fan, Li; Li, Fengmin; Huang, Qiliang

2013-01-01

14

Towards highly accurate ab initio thermochemistry of larger systems: Benzene  

Science.gov (United States)

The high accuracy extrapolated ab initio thermochemistry (HEAT) protocol is applied to compute the total atomization energy (TAE) and the heat of formation of benzene. Large-scale coupled-cluster calculations with more than 1500 basis functions and 42 correlated electrons as well as zero-point energies based on full cubic and (semi)diagonal quartic force fields obtained with the coupled-cluster singles and doubles with perturbative treatment of the triples method and atomic natural orbital (ANO) triple- and quadruple-zeta basis sets are presented. The performance of modifications to the HEAT scheme and the scaling properties of its contributions with respect to the system size are investigated. A purely quantum-chemical TAE and associated conservative error bar of 5463.0 +/- 3.1 kJ mol-1 are obtained, while the corresponding 95% confidence interval, based on a statistical analysis of HEAT results for other and related molecules, is +/- 1.8 kJ mol-1. The heat of formation of benzene is determined to be 101.5 +/- 2.0 kJ mol-1 and 83.9 +/- 2.1 kJ mol-1 at 0 K and 298.15 K, respectively.

Harding, Michael E.; Vázquez, Juana; Gauss, Jürgen; Stanton, John F.; Kállay, Mihály

2011-07-01

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Association between intrafollicular concentration of benzene and outcome of controlled ovarian stimulation in IVF/ICSI cycles: a pilot study  

Science.gov (United States)

Background Several studies have shown that exposure to benzene is associated to menstrual disorders, miscarriages and other disorders of the reproductive system. We performed an observational prospective pilot study to evaluate if levels of benzene in follicular fluid were correlated with response to controlled ovarian stimulation. Method Thirty-four normogonadotrophic women undergoing IVF were enrolled. Intra-follicular benzene levels were evaluated by chromatography/mass spectrometry. Based on median benzene level, we divided the study population in two groups: Group A with a “low” intra-follicular benzene concentration (n?=?19, benzene IVF were analyzed in the two groups. Results The two groups did not differ in terms of demographic or anthropometric characteristics. Group B had significantly higher basal FSH levels, lower estradiol peak concentration, and fewer oocytes retrieved and embryos transferred (p?benzene levels.

2014-01-01

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On-line monitoring of benzene air concentrations while driving in traffic by means of isotopic dilution gas chromatography/mass spectrometry.  

Science.gov (United States)

There is no shortage of information about the average benzene concentrations in urban air, but there is very little about microenvironmental exposure, such as in-vehicle concentrations while driving in various traffic conditions, while refuelling, or while in a parking garage. The main reason for this lack of data is that no analytical instrumentation has been available to measure on-line trace amounts of benzene in such situations. We have recently proposed a highly accurate, high-speed cryofocusing gas chromatography/mass spectrometry (GC/MS) system for monitoring benzene concentrations in air. Accuracy of the analytical data is achieved by enrichment of the air sample before trapping, with a stable isotope permeation tube system. The same principles have been applied to a new instrument, specifically designed for operation on an electric vehicle (Ducato Elettra, Fiat). The zero emission vehicle and the fully transportable, battery-operated GC/MS system provide a unique possibility of monitoring benzene exposure in real everyday situations such as while driving, refuelling, or repairing a car. All power consumptions have been reduced so as to achieve a battery-operated GC/MS system. Liquid nitrogen cryofocusing has been replaced by a packed, inductively heated, graphitized charcoal microtrap. The instrument has been mounted on shock absorbers and installed in the van. The whole system has been tested in both fixed and mobile conditions. The maximum monitoring period without external power supply is 6 h. The full analytical cycle is 4 min, allowing close to real-time monitoring, and the minimum detectable level is 1 microgram/m3 for benzene. In-vehicle monitoring showed that, when recirculation was off and ventilation on, i.e., air from outside the vehicle was blown inside, concentrations varied widely in different driving conditions: moving from a parking lot into normal traffic on an urban traffic condition roadway yielded an increase in benzene concentration from 17 to 62.3 micrograms/m3 even if the actual distance was small. A larger increase was observed when a car was left with the engine running at a distance 2 m from the zero emission vehicle: We measured an increment of benzene concentrations from 15.2 to 174.4 micrograms/m3 with a car equipped with a catalytic converter, and from 19.1 to 386.3 micrograms/m3 with a car without such a converter. PMID:8738357

Davoli, E; Cappellini, L; Moggi, M; Ferrari, S; Fanelli, R

1996-01-01

17

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

Science.gov (United States)

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

Olszowski, Tomasz; K?os, Andrzej

2013-11-01

18

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)

1994-05-01

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Low cost benzene reduction for RFG  

Energy Technology Data Exchange (ETDEWEB)

In the typical refinery benzene comes from several sources including: light straight run gasoline, isomerate, reformate, hydrocrackate, FCC gasoline, and coker gasoline. However the benzene from the reformer usually represents 50--80% of the total. As a result the reformate is the natural place to focus benzene reduction. The benzene content of the reformate is normally in the range of 2.5 to 8 volume %. The higher benzene concentrations occur in high pressure reformers due to hydrodealkylation of toluene and heavier alkylbenzenes. Benzene can be reduced in the reformate by removing benzene precursors such as cyclic C{sub 6}`s in the reformer feed. However, hydrodealkylation of other aromatics in the reformer will still leave a reformate benzene content of 1 to 1.5 volume %. More complete control of benzene can be achieved by removing it from the reformate rather than by treating the reformer feed stream. The paper describes the conventional benzene saturation process and the CDHydro process, which combines fractionation with hydrogenation. Capitalized costs are summarized. Refiners can maintain gasoline compositions with high aromatic contents by using the flexibility offered by the Complex Model. CDHydro provides a very cost effective method of benzene control for the refiner. Benzene reduction targets for both 1995 and 2000 are easily met. CDHydro can provide much higher benzene removal than required by the models, thus giving the refiner valuable options for averaging and trading credits.

Rock, K.L. [CDTECH, Houston, TX (United States)

1995-09-01

20

Highly selective synthesis of (E)-alkenyl-(pentafluorosulfanyl)benzenes through Horner–Wadsworth–Emmons reaction  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Diethyl 2-nitro-(pentafluorosulfanyl)benzylphosphonates, available by the vicarious nucleophilic substitution reaction of meta- and para-nitro-(pentafluorosulfanyl)benzenes and diethyl chloromethylphosphonate, undergo Horner–Wadsworth–Emmons reaction with aldehydes in the presence of potassium hydroxide in acetonitrile at ambient temperature to give (E)-2-nitro-1-alkenyl-(pentafluorosulfanyl)benzenes in good yields and high stereoselectivities. Follow-up transformations of the primary pro...

Iakobson, George; Beier, Petr

2012-01-01

 
 
 
 
21

Al-pillared clays supported rare earths and palladium catalysts for deep oxidation of low concentration of benzene  

Science.gov (United States)

Al-pillared clays supported rare earths (RE/Al-PILC) are prepared and used as supports of palladium catalysts for deep oxidation of low concentrations of benzene (130-160 ppm). The supports and catalysts are characterized by X-ray powder diffraction (XRD), FT-IR, BET, transmission electron microscopy (TEM) and temperature-programmed reduction (H 2-TPR). The results show that Al-pillaring results in a strong increase in the basal spacing ( d0 0 1 ) from about 1.2 to 1.8 nm, and an increase in the BET surface area from 63.6 (±3.2) to 238.8 (±11.9) m 2/g. Activity tests of deep oxidation of low concentration benzene show catalysts supported on Al-PILC and RE/Al-PILC are obviously more active than that on raw clay. Pd/6% Ce/Al-PILC, in particular, can catalyze the complete oxidation of low concentration benzene at a temperature as low as about 290 °C.

Zuo, Shufeng; Zhou, Renxian

2006-12-01

22

Al-pillared clays supported rare earths and palladium catalysts for deep oxidation of low concentration of benzene  

Energy Technology Data Exchange (ETDEWEB)

Al-pillared clays supported rare earths (RE/Al-PILC) are prepared and used as supports of palladium catalysts for deep oxidation of low concentrations of benzene (130-160 ppm). The supports and catalysts are characterized by X-ray powder diffraction (XRD), FT-IR, BET, transmission electron microscopy (TEM) and temperature-programmed reduction (H{sub 2}-TPR). The results show that Al-pillaring results in a strong increase in the basal spacing (d{sub 001}) from about 1.2 to 1.8 nm, and an increase in the BET surface area from 63.6 ({+-}3.2) to 238.8 ({+-}11.9) m{sup 2}/g. Activity tests of deep oxidation of low concentration benzene show catalysts supported on Al-PILC and RE/Al-PILC are obviously more active than that on raw clay. Pd/6% Ce/Al-PILC, in particular, can catalyze the complete oxidation of low concentration benzene at a temperature as low as about 290 deg. C.

Zuo Shufeng [Institute of Catalysis, Zhejiang University, Hangzhou 310028 (China); Zhou Renxian [Institute of Catalysis, Zhejiang University, Hangzhou 310028 (China)]. E-mail: zhourenxian@zju.edu.cn

2006-12-30

23

Al-pillared clays supported rare earths and palladium catalysts for deep oxidation of low concentration of benzene  

International Nuclear Information System (INIS)

Al-pillared clays supported rare earths (RE/Al-PILC) are prepared and used as supports of palladium catalysts for deep oxidation of low concentrations of benzene (130-160 ppm). The supports and catalysts are characterized by X-ray powder diffraction (XRD), FT-IR, BET, transmission electron microscopy (TEM) and temperature-programmed reduction (H2-TPR). The results show that Al-pillaring results in a strong increase in the basal spacing (d001) from about 1.2 to 1.8 nm, and an increase in the BET surface area from 63.6 (±3.2) to 238.8 (±11.9) m2/g. Activity tests of deep oxidation of low concentration benzene show catalysts supported on Al-PILC and RE/Al-PILC are obviously more active than that on raw clay. Pd/6% Ce/Al-PILC, in particular, can catalyze the complete oxidation of low concentration benzene at a temperature as low as about 290 deg. C

2006-12-30

24

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

25

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

26

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)

1979-01-01

27

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 approach to the preparation of a wide variety of environmental sample types using similar chemistry for all samples

1991-11-01

28

Surface Patterning of Benzene Carboxylic Acids on Graphite: Influence of structure, solvent, and concentration on molecular self-assembly  

Science.gov (United States)

Scanning tunneling microscopy (STM) was used to investigate the molecular self-assembly of four different benzene carboxylic acid derivatives at the liquid/graphite interface: pyromellitic acid (1,2,4,5-benzenetetracarboxylic acid), trimellitic acid (1,2,4-benzenetricarboxylic acid), trimesic acid (1,3,5-benzenetricarboxylic acid), and 1,3,5-benzenetriacetic acid. A range of two dimensional networks are observed that depend sensitively on the number of carboxylic acids present, the nature of the solvent, and the solution concentration. We will describe our recent efforts to determine (a) the preferential two-dimensional structure(s) for each benzene carboxylic acid at the liquid/graphite interface, (b) the thermodynamic and kinetic factors influencing self-assembly (or lack thereof), (c) the role solvent plays in the assembly, (e) the effect of in situ versus ex situ dilution on surface packing density, and (f) the temporal evolution of the self-assembled monolayer. Results of computational analysis of analog molecules and model monolayer films will also be presented to aid assignment of network structures and to provide a qualitative picture of surface adsorption and network formation.

Florio, Gina; Stiso, Kimberly; Campanelli, Joseph; Dessources, Kimberly; Folkes, Trudi

2012-02-01

29

Chromosome aberration, sister-chromatid exchange, proliferative rate index, and serum thiocyanate concentration in smokers exposed to low-dose benzene  

Energy Technology Data Exchange (ETDEWEB)

Cytogenetical endpoints, i.e., chromosome aberration (CA), sister-chromatid exchange (SCE), and proliferative rate indexes (PRI), were measured in peripheral blood lymphocytes (PBL) of 42 workers exposed occupationally to low-dose benzene, and of 42 controls. The role of smoking habit as a confounding factor of genotoxic effects caused by occupational low-dose benzene exposure was also studied. The benzene concentrations in the ambient air samples varied from 3 to 20 mg/m{sup 3} (mean: 7 mg/m{sup 3}). The continuous low-dose benzene exposure significantly increased the CA and SCE frequencies, but did not influence PRI. Smoking levels were characterized by subjective accounts and by serum thiocyanate concentrations (SCN). CA and SCE were not significantly increased in smokers compared to nonsmokers, but the differences were expressed to a greater extent in the case of measurement of SCN concentrations. Determination of SCN proved to be more objective in the assessment of genotoxic effects of smoking as a confounding factor of occupational low-dose benzene exposure. 42 refs., 4 tabs.

Major, J.; Jakab, M.; Kiss, G. [National Institute of Occupational Health, Budapest (Hungary)] [and others

1994-12-31

30

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

1999-01-01

31

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

Energy Technology Data Exchange (ETDEWEB)

The effect of the colloidal particle concentration on the structure of the magnetite/C{sub 6}D{sub 6} 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.)

Aksenov, V.; Avdeev, M. [Frank Laboratory of Neutron Physics, JINR, 141980 Moscow Region, Dubna (Russian Federation); Balasoiu, M. [Frank Laboratory of Neutron Physics, JINR, 141980 Moscow Region, Dubna (Russian Federation); Institute of Space Sciences, 76900 Bucharest (Romania); Rosta, L.; Toeroek, G. [Research Institute for Solid State Physics and Optics, KFKI, 1525 Budapest (Hungary); Vekas, L.; Bica, D. [Center of Fundamental and Advanced Technical Research, Timisoara Branch of RAS, Timisoara-1900 (Romania); Garamus, V. [GKSS Research Centre, 21502 Geesthacht (Germany); Kohlbrecher, J. [Paul Scherrer Institut, 5232 Villigen (Switzerland)

2002-07-01

32

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.)

2002-01-01

33

Occupational exposure to benzene in the shoe industry  

Energy Technology Data Exchange (ETDEWEB)

In order to determine the possible actual exposure to benzene in the shoe industry from industrially used solvents, glues, and paints containing benzene as a nondeclared constituent, phenol in urine and benzene in blood, as indices of internal exposure to benzene, were measured in workers (N = 33). Since toluene, in contrast to benzene, is declared as a constituent in several glues, toluene in the blood of workers was also analysed. All analyses were performed using gas chromatography. Urine samples were collected on Monday morning (MI) before work and on Wednesday (WI) before and (WII) after work. Venous blood samples were taken on Wednesday only, 1/2 hour after work. There was no difference in the phenol concentrations of MI and WI, while the phenol concentration of WII was about twice as high as that in WI. In all blood samples, benzene was found, as well as toluene, which was about four times higher in comparison with benzene. A correlation (r = 0.465; p less than .01) was found between the difference in pre- and postshift phenol concentrations (WII-WI) in urine and the benzene concentrations in blood. The results presented show that a trace amount of benzene, which is often not declared as a constitutent in industrially used chemicals, could be a source of marked exposure to benzene. It can also be concluded that changes in phenol in urine (if preshift and postshift samples are taken) might be a sufficiently sensitive parameter to assess exposure to benzene even when other data concerning the presence of benzene in the working atmosphere are not available.

Karacic, V.; Skender, L.; Prpic-Majic, D.

1987-01-01

34

High resolution Raman study of phonon and vibron bandwidths in isotopically pure and natural benzene crystal  

Science.gov (United States)

The frequency and the bandwidth of the 12 Raman active lattice modes and of more than 45 internal vibrons of natural and 12C isotopically pure benzene have been measured under high resolution with the aid of a tandem interferometer-spectrometer system or alternatively of a two meter focal length grating Sopra spectrometer. For five lattice phonons and for several vibrons the measurements were extended to a sufficient temperature range to study the relaxation processes in terms of anharmonic phonon-phonon and phonon-vibron coupling processes. The effect of the isotopic impurities on the phonon lifetime has been shown to be very important for some vibrons, in particular, for those resonant with the impurity level. The bandwidth evolution with temperature has been interpreted in terms of down- and up- three- and four-phonon as well as of dephasing processes.

Pinan, J. P.; Ouillon, R.; Ranson, P.; Becucci, M.; Califano, S.

1998-10-01

35

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 health risk. The lifetime excess Cancer Risk (CR) and Overall Risk Probability for cancer on exposure to benzene was calculated for all Scenarios and this was higher amongst service station attendants than any other scenario.

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

2014-01-01

36

Unusually high indoor radon concentrations  

International Nuclear Information System (INIS)

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

1993-01-01

37

Unusually high indoor radon concentrations  

Science.gov (United States)

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

Ennemoser, O.; Ambach, W.; Brunner, P.; Schneider, P.; Oberaigner, W.; Purtscheller, F.; Stingl, V.

38

Unusually high indoor radon concentrations  

Energy Technology Data Exchange (ETDEWEB)

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

Ennemoser, O.; Ambach, W. (Innsbruck Univ. (Austria). Inst. fuer Medizinische Physik); Brunner, P.; Schneider, P. (Department of Radiation Protection and Nuclear Technology, Innsbruck (Austria)); Oberaigner, W. (Cancer Registry of Tirol, Innsbruck (Austria)); Purtscheller, F. (Innsbruck Univ. (Austria). Inst. fuer Mineralogie und Petrographie); Stingl, V. (Innsbruck Univ. (Austria). Inst. of Geology amd Palaeontology)

1993-01-01

39

[Exposure to benzene of service station employees and composition of benzene].  

Science.gov (United States)

The International Agency for Research on Cancer (IARC) classifies gasoline vapours and exhaust fumes from gasoline fueled automobiles as potential human carcinogens. Data on the chemical composition of gasoline marketed in Italy and especially on the concentration of benzene, are rather poor. Within the framework of an investigation aimed at assessing the mean annual level of exposure to aromatic hydrocarbons among gasoline pump attendants, made on a sample of attendants in Rome between December 1991 and November 1992, samples of gasoline were also collected so as to determine the benzene content of the gasoline over the investigation period, assess the variability of benzene concentration in the various gasolines and according to the season of the year, and take account of gasoline composition in analysing the factors determining individual exposure levels of pump attendants. Benzene exposure was measured via gas chromatography of air samples obtained with personal pumps in the breathing zone. The mean benzene exposure level (8 h TWA) of the 27 subjects under study was 1.73 mg/m3 (SD = 5.53). The benzene concentration in the samples of gasoline, which were collected on the same day as personal exposure monitoring was performed, was measured by means of high resolution gas chromatography (hr-GC). Mean benzene levels of 25.03 g/l (SD = 3.47), equivalent to 2.86% by volume, were measured in 24 samples of alkylated gasoline, and mean levels of 23.18 g/l (SD = 3.93), equivalent to 2.65% v/v, were measured in 10 samples of lead-free gasoline. Statistically significant associations were found between individual exposure to benzene and the quantity of gasoline pumped (r = 0.69) and the quantity of benzene present in the gasoline sold on the day monitoring was performed (r = 0.70). Using regression analysis, the estimated increase in the level of personal benzene exposure was 0.01 mg/m3 for every increase of 100 g in the benzene content of the total amount of gasoline sold. This estimation could be used to quantify the expected reduction in benzene exposure levels in service station attendants following a reduction in the benzene content of gasoline. PMID:7885296

Lagorio, S; Fuselli, S; Iavarone, I; Vanacore, N; Carere, A

1994-01-01

40

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

Directory of Open Access Journals (Sweden)

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

Benjamin Edokpolo

2014-06-01

 
 
 
 
41

High-concentration tritium sensor  

International Nuclear Information System (INIS)

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-?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.

2004-09-12

42

Advanced high efficiency concentrator cells  

Energy Technology Data Exchange (ETDEWEB)

This report describes research to develop the technology needed to demonstrate a monolithic, multijunction, two-terminal, concentrator solar cell with a terrestrial power conversion efficiency greater than 35%. Under three previous subcontracts, Varian developed many of the aspects of a technology needed to fabricate very high efficiency concentrator cells. The current project was aimed at exploiting the new understanding of high efficiency solar cells. Key results covered in this report are as follows. (1) A 1.93-eV AlGaAs/1.42-eV GaAs metal-interconnected cascade cell was manufactured with a one-sun efficiency at 27.6% at air mass 1.5 (AM1.5) global. (2) A 1.0eV InGaAs cell was fabricated on the reverse'' side of a low-doped GaAs substrate with a one-sun efficiency of 2.5% AM1.5 diffuse and a short-circuit current of 14.4 mA/cm{sup 2}. (3) Small-scale manufacturing of GaAs p/n concentrator cells was attempted and obtained an excellent yield of high-efficiency cells. (4) Grown-in tunnel junction cell interconnects that are transparent and thermally stable using C and Si dopants were developed. 10 refs.

Gale, R. (Varian Associates, Inc., Palo Alto, CA (United States). Varian Research Center)

1992-06-01

43

Study of benzene and toluene adsorption on granular activated carbon  

Energy Technology Data Exchange (ETDEWEB)

Benzene and toluene are among the organic compounds designated by EPA as priority pollutants because of their toxicity to man and the environment. Activated carbon has been used to remove organic compounds from waters for many years. However, little or no information is available in the literature on the removal of specific organic compounds by activated carbon. Therefore, this study was undertaken to investigate the adsorption of benzene and toluene from aqueous solutions onto granular activated carbon. Calgon Filtrasorb 400 carbon was used as the adsorbent. The samples were analyzed on a Perkin-Elmer Sigma 3B gas chromatograph with flame ionization equipped with an HS-6 Head Space Sampler. The data fit the Freundlich isotherm model well with a high correlation coefficient. The pH of the test solutions at 3, 6.5, and 9 shows no effect on benzene adsorption and slight effect on toluene adsorption. The study shows that the amount of benzene or toluene adsorbed increases with increasing initial concentrations. Competitive adsorption of benzene and toluene when present in aqueous mixtures together and with chloroform, acetone, and tert-butanol, shows a significant reduction in benzene adsorption and a little effect on toluene adsorption. Also this study shows that ozone oxidizes benzene and toluene more effectively at pH 3 and 6.5 than at pH 9. The benzene adsorption is reduced somewhat in the presence of ozone byproducts of benzene. However, the toluene adsorption is enhanced in the presence of toluene ozonation byproducts.

Samaneh, T.S.A.

1981-01-01

44

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

1997-01-01

45

090320 benzene supplementary note final  

…1 Introduction 1 2 Plant uptake review 2 2.1 Literature search strategy 2 2.2 Plant processes and phytotoxicity 2 2.3 Soil-to-plant concentration factors 3 2.4 Summary and recommendations 5 References 6 Technical Review Benzene - Supplementary information for the derivation of SGV for benzene 1 1 Introduction…

46

Self-diffusion in supercritical water and benzene in high-temperature high-pressure conditions studied by NMR and dynamic solvation-shell model  

Science.gov (United States)

The self-diffusion coefficients of water and organic solvents in the high-temperature high-pressure conditions are studied by using high-temperature NMR and MD simulation methods. The experimental results are analyzed using a scheme based on the solvation shell relaxation time obtained by MD simulation. The dynamic effect of hydrogen bonding is discussed through the comparison between water and a nonpolar organic solvent, benzene, over a wide range of density and temperature. The hydrogen-bonding effects are as follows: (1) the self-diffusion coefficient of water depends on density more weakly than that of benzene, (2) the self-diffusion coefficient of water at the ambient density depends on temperature more strongly than that of benzene at the density, (3) the turnover from the mobile-shell type to the in-shell type with increasing density does not occur in supercritical water up to the ambient density, whereas such turnover is observed in benzene. These contrasts are reflecting the dynamic effect of the anisotropic attractive interactions.

Yoshida, Ken; Matubayasi, Nobuyuki; Uosaki, Yasuhiro; Nakahara, Masaru

2010-03-01

47

High performance Fresnel-based photovoltaic concentrator.  

Science.gov (United States)

In order to achieve competitive system costs in mass-production, it is essential that CPV concentrators incorporate sufficient manufacturing tolerances. This paper presents an advanced concentrator optic comprising a Fresnel lens and a refractive secondary element, both with broken rotational symmetry, an optic producing both the desired light concentration with high tolerance (high acceptance angle) as well as an excellent light homogenization by Köhler integration. This concentrator compares well with conventional Fresnel-based CPV concentrators. PMID:20607884

Benítez, Pablo; Miñano, Juan C; Zamora, Pablo; Mohedano, Rubén; Cvetkovic, Aleksandra; Buljan, Marina; Chaves, Julio; Hernández, Maikel

2010-04-26

48

Photocatalytic decomposition of benzene by porous nanocrystalline ZnGa2O4 with a high surface area.  

Science.gov (United States)

Porous nanocrystalline ZnGa2O4 catalysts were synthesized by a simple soft-chemical method at low temperature. The catalysts were characterized by XRD, nitrogen adsorption, SEM, TEM, UV/ vis, and FT-IR spectroscopy. The activity of the photocatalysts was evaluated by decomposition of benzene and its derivatives in the gas phase. It was found that hydrothermal treatment resulted in the formation of spinel ZnGa2O4 with a large surface area of 43-201 m2 x g(-1) depending on the synthetic temperature. The optimum synthetic temperature was found to be 80 degrees C, at which the sample possessed a surface area of 201 m2 x g(-1) and had the highest photocatalytic activity for degrading benzene. A comparison with TiO2 and Pt/TiO2 showed that the ZnGa2O4 (synthesized at 80 degrees C) had improved photocatalytic activity and durability over the TiO2-based catalysts. No remarkable deactivation of the ZnGa2O4 catalyst was observed in 80 h photoreaction, whereas the TiO2 deactivated remarkably in 24 h reaction. The high photocatalytic performance of porous ZnGa2O4 catalysts can be explained by the large specific surface area, the accessible porous framework, and the high redox power. PMID:19731702

Zhang, Xinnian; Huang, Jianhui; Ding, Kaining; Hou, Yidong; Wang, Xinchen; Fu, Xianzhi

2009-08-01

49

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

50

Reduction of benzene in gasoline  

Energy Technology Data Exchange (ETDEWEB)

The benzene concentration in the gasoline pool of a petroleum refinery is decreased by alkylation of the benzene in a catalytic dewaxing reactor using the olefinic by-products from the dewaxing reaction as alkylating agents. The catalytic dewaxing is preferably carried out in the presence of an intermediate pore size zeolite such as ZSM-5 using a distillate or lube boiling range dewaxing feed. The benzene rich feed preferably contains less than about 2% C[sub 7+] aromatics in order to reduce alkylation on non-objectionable species in the reformate. (author)

Harandi, M.N.

1992-09-17

51

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

International Nuclear Information System (INIS)

Nanowire-nanocluster hybrid chemical sensors were realized by functionalizing gallium nitride (GaN) nanowires (NWs) with titanium dioxide (TiO2) 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 TiO2 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 TiO2 clusters after post-deposition anneal at 700 deg. C. A change of current was observed for these hybrid sensors when exposed to the vapors of aromatic compounds (benzene, toluene, ethylbenzene, xylene and chlorobenzene mixed with air) under UV excitation, while they had no response to non-aromatic organic compounds such as methanol, ethanol, isopropanol, chloroform, acetone and 1,3-hexadiene. The sensitivity range for the noted aromatic compounds except chlorobenzene were from 1% down to 50 parts per billion (ppb) at room temperature. By combining the enhanced catalytic properties of the TiO2 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.

2011-07-22

52

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 (TiO2) 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 TiO2 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 TiO2 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 TiO2 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.

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

2011-07-01

53

Proposal of structures possessing high exciton concentration  

Energy Technology Data Exchange (ETDEWEB)

The possibility of achievement of high exciton concentrations is analyzed. It is shown that high concentrations can be achieved in a three-layer thin molecular film due to the autoreduction processes taking place in it. Shortly, the appearance of high concentrations is the consequence of boundary conditions in film and of the magnitude of matrix elements of dipol-dipol interactions. The autoreduction takes place in the cases when matrix elements characterizing exciton transfer are less than statistical matrix elements. Based on numerical analysis, it was found that optical quanta concentrations of a three-layer film can achieve values of about 5x10{sup -2}. The structures possessing so high concentration do not exist in nature, thus they have to be synthesised. For the current state of nanotechnology, it is not a problem. Fortunately achieving high concentrations requires only certain ratios of relevant characteristics of the film with a two-level exciton scheme, but not their single values.

Sajfert, Vjekoslav [Technical Faculty ' Mihajlo Pupin' , Zrenjanin (Serbia)], E-mail: sajfertv@ptt.yu; Jacimovski, Stevo [Faculty of Electrotechnic Sciences, Belgrade (Serbia); Tosic, Bratislav [Vojvodina Academy of Sciences and Arts, Novi Sad (Serbia)

2008-09-15

54

Proposal of structures possessing high exciton concentration  

International Nuclear Information System (INIS)

The possibility of achievement of high exciton concentrations is analyzed. It is shown that high concentrations can be achieved in a three-layer thin molecular film due to the autoreduction processes taking place in it. Shortly, the appearance of high concentrations is the consequence of boundary conditions in film and of the magnitude of matrix elements of dipol-dipol interactions. The autoreduction takes place in the cases when matrix elements characterizing exciton transfer are less than statistical matrix elements. Based on numerical analysis, it was found that optical quanta concentrations of a three-layer film can achieve values of about 5x10-2. The structures possessing so high concentration do not exist in nature, thus they have to be synthesised. For the current state of nanotechnology, it is not a problem. Fortunately achieving high concentrations requires only certain ratios of relevant characteristics of the film with a two-level exciton scheme, but not their single values

2008-09-01

55

Accumulation of chlorinated benzenes in earthworms  

Energy Technology Data Exchange (ETDEWEB)

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

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

1996-12-31

56

Measurements of benzene, toluene and xylenes in urban air  

Science.gov (United States)

Results from measurements of benzene, toluene and xylenes in the city centre of Oslo are presented. The samples were collected in March and August/September 1980 at two of the stations used in an air pollution monitoring program. One was in a street canyon station and the other was a reference station. The sampling equipment was two charcoal filters in series, placed in a filter holder with a disk of glass fibre prefilter in front. Analysis was by high resolution gas chromatography. The single measured separate values of these aromatics ranged from 1 to 210?m -3. Benzene concentrations especially ranged from 4 to 114 ?g m -3. The concentrations of benzene and toluene seemed to be higher in August/September than in March, while the concentrations of the xylenes seemed to be about the same. The variations in concentrations of the aromatics follow each other closely in both measuring periods which indicates that all components are emitted from the same sources and are dispersed in the same way. Correlation between benzene and CO and between benzene and ambient temperature are discussed.

Wathne, Bente M.

57

Benzene hematotoxicity and leukemogenesis  

Energy Technology Data Exchange (ETDEWEB)

Eight-to-twelve-week-old male and female C57B1/6 BNL mice were exposed to air or benzene vapor in air at a concentration of 10, 25, 100, 300, or 400 ppm. Benzene at concentrations of 100 ppm or higher for 10 exposures of 6 hours per day 5 days a week produced a reduction in bone marrow cellularity and the number of pluripotent stem cells in the bone marrow. The fraction of stem cells in DNA synthesis was also increased. Exposure to 300 ppm 6 hours a day 5 days a week for 2, 4, 8, and 16 weeks produced a diminution in the stem cell levels in bone marrow which returned to those of controls 2 weeks after benzene exposure for 2 and 4 weeks, 16 weeks after exposure for 8 weeks, and to 92% of controls 25 weeks after 16 weeks of exposure. There was a more rapid return of blood lymphocytes to the control level. Mice exposed to 300 ppm for 6 hours/day, 5 days per week for 16 weeks began dying at 330 days of age, whereas no deaths were observed in sham-exposed mice until 440 days of age. The benzene-exposed mice died in two waves: the first was from 330-390 days of age, with a second wave commencing at 570 days of age. The first wave of mortality was due primarily to thymic lymphomata. The second wave was due to a mixture of nonthymic lymphomata and solid tumors. 19 references, 7 figures, 1 table.

Cronkite, E.P.; Drew, R.T.; Inoue, T.; Bullis, J.E.

1985-01-01

58

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

Energy Technology Data Exchange (ETDEWEB)

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 HNO{sub 3}) revealed that ternary mixer of uranium, americium and plutonium or thorium, americium and plutonium could be separated from each other at 1 M HNO{sub 3}. Desorption of U(VI), Pu(IV) and Am(III) from the loaded resin was efficiently carried out using 0.1 M {alpha}-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 HNO{sub 3} 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.

Ansari, S.A.; Mohapatra, P.K. [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai, 400085 (India); Manchanda, V.K. [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai, 400085 (India)], E-mail: vkm@barc.gov.in

2009-01-30

59

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

Science.gov (United States)

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((R)). 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 (0.01-6M HNO(3)) revealed that ternary mixer of uranium, americium and plutonium or thorium, americium and plutonium could be separated from each other at 1M HNO(3). Desorption of U(VI), Pu(IV) and Am(III) from the loaded resin was efficiently carried out using 0.1M alpha-HIBA, 0.25M oxalic acid and 0.01M EDTA, respectively. Quantitative pre-concentration of actinide ions such as Th(IV) and U(VI) was possible from 3M HNO(3) 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. PMID:18541366

Ansari, S A; Mohapatra, P K; Manchanda, V K

2009-01-30

60

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

2009-01-30

 
 
 
 
61

Highly sensitive determination of methotrexate at poly (l-lysine) modified electrode in the presence of sodium dodecyl benzene sulfonate.  

Science.gov (United States)

A simple and sensitive electrochemical sensor based on poly (l-lysine) modified glassy carbon electrode (PLL/GCE) was developed to sensitively detect methotrexate (MTX) in the presence of sodium dodecyl benzene sulfonate (SDBS). Fourier transform infrared spectroscopy, electrochemical impedance spectroscopy and cyclic voltammetry were carried out to characterize PLL film which exhibits excellent electrocatalytic activity toward the oxidation of MTX in 0.1M phosphate buffer solution. In addition, the oxidation peak of MTX remained stable at PLL/GCE in the presence of SDBS and its current increased 8 times compared with that at bare GCE without SDBS. Experimental parameters were optimized with regard to pH, electro-polymerization segment, accumulation time and concentration of SDBS. Under optimum conditions, the square wave voltammograms exhibited that the oxidation peak current was linearly proportional to the concentration of MTX in the range of 5nM - 0.2?M with detection limit of 1.7 (±0.06) nM (S/N=3). Moreover, this method was applied to detect MTX in medicinal tablets with satisfying results. PMID:24727063

Wei, Youli; Luo, Liqiang; Ding, Yaping; Si, Xiaojing; Ning, Yanqun

2014-08-01

62

090320 benzene supplementary note final  

…-plant concentration factors for the produce categories used within the CLEA model. Section 2.3 provides a review of the available literature. It attempts to recommend soil-to-plant concentration factors for use in the CLEA model for deriving Soil Guideline Values (SGVs). Technical Review Benzene - Supplementary…

63

Producing a highly concentrated coal suspension  

Energy Technology Data Exchange (ETDEWEB)

Coal from wet and dry grinding is loaded into a mixer with a mixer arm with the acquisition of a highly concentrated suspension. Foamers (for instance, alkylbenzolsulfonate) and foam stabilizers (for instance diethanolamide of lauric acid) are added in a ratio of 10 to (2 to 5). The high fluidity of the suspension is maintained by injecting air into the suspension and an 80 percent concentration of the suspension is achieved.

Mokudzu, K.; Atsudzima, T.; Kiyedzuka, Y.

1983-06-03

64

Temporal changes in U.S. benzene emissions inferred from atmospheric measurements.  

Science.gov (United States)

The 1990 Clean Air Act Amendments required the United States Environmental Protection Agency (U.S. EPA) to enact stricter regulations aimed at reducing benzene emissions. In an effort to determine whether these new regulations have been successful in reducing atmospheric benzene concentrations, we have evaluated benzene-to-acetylene ratios from data sets spanning nearlythree decades, collected during several field studies and from the U.S. EPA's Photochemical Assessment Monitoring Station (PAMS) network. The field-study data indicate a decrease in benzene relative to acetylene of approximately 40% from 1994 to 2002. This corresponds to a decrease in benzene alone of approximately 56% over the same period. In contrast, the PAMS data exhibit high interannual variability with no discernible trend. This discrepancy is attributed to measurement problems in the PAMS data sets. PMID:15819191

Fortin, Tara J; Howard, Benjamin J; Parrish, David D; Goldan, Paul D; Kuster, William C; Atlas, Eliot L; Harley, Robert A

2005-03-15

65

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

66

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

1989-01-01

67

090320 benzene supplementary note final  

…various extents - depending on plant species - by loss through volatilisation and transpiration. Gaseous pollutants primarily enter leaves via their stomata, but can also be absorbed through the epidermis of aboveground parts. Surveys of benzene concentrations in plants have found that they tend to accumulate…

68

Facts about Benzene  

Science.gov (United States)

... for All Disasters Illness Injury Food & Water Animals & Insects Returning Home After a Disaster Carbon Monoxide Environmental ... to benzene in the air. If the benzene release was outside, move away from the area where ...

69

?-galactosidase stability at high substrate concentrations.  

Science.gov (United States)

Enzymatic synthesis of galacto-oligosaccharides is usually performed at high initial substrate concentrations since higher yields are obtained. We report here on the stability of ?-galactosidase from Bacillus circulans at 25, 40, and 60°C in buffer, and in systems with initially 5.0 and 30% (w/w) lactose. In buffer, the half-life time was 220 h and 13 h at 25 and 40°C, respectively, whereas the enzyme was completely inactivated after two hours at 60°C. In systems with 5.0 and 30% (w/w) lactose, a mechanistic model was used to correct the oNPG converting activity for the presence of lactose, glucose, galactose, and oligosaccharides in the activity assay. Without correction, the stability at 5.0% (w/w) lactose was overestimated, while the stability at 30% (w/w) lactose was underestimated. The inactivation constant k d was strongly dependent on temperature in buffer, whereas only a slight increase in k d was found with temperature at high substrate concentrations. The enzyme stability was found to increase strongly with the initial substrate concentrations. The inactivation energy E a appeared to be lower at high initial substrate concentrations. PMID:24024090

Warmerdam, Anja; Boom, Remko M; Janssen, Anja Em

2013-01-01

70

High level waste concentrate storage at WAK  

International Nuclear Information System (INIS)

The fission product waste solution originating from the chemical reprocessing of nuclear fuels is concentrated in an evaporator and transferred to an interim storage tank. The Karlsruhe nuclear reprocessing plant (WAK) is in possession of 4 storage tanks for high active waste concentrate (HAWC), two of them containing HAWC and two empty reserve tanks. In the beginning of 1987 63 m3 HAWC were transferred from an old tank farm (HWL) to a new one (LAVA). This paper reports the experiences gained at WAK during handling, storage and transfer of HAWC

1987-01-01

71

090323 Benzene SGV final  

…hydrodealkylation (ATSDR, 2007). The major impurities found in commercial benzene are toluene, xylene, phenol, thiophene, carbon disulphide, acetylnitrile and pyridine (ATSDR, 2007). Benzene is used throughout the world in enormous quantities. Other than its use as an additive to petrol, the vast majority of benzene

72

Biotransformation of toluene, benzene and naphthalene under anaerobic conditions.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Aromatic hydrocarbons are widespread in nature, due to increasing industrial activity, and often contribute to polluted soils, sediments, and groundwater. Most of these compounds are toxic at relatively high concentrations, but some are already carcinogenic at very low concentrations, e.g. benzene. A growing awareness of the health risks associated with contamination has directed research to the removal or degradation of such compounds. The use of microorganisms to degrade toxic compounds (bi...

1997-01-01

73

Biomarkers of environmental benzene exposure  

Energy Technology Data Exchange (ETDEWEB)

Environmental exposures to benzene result in increases in body burden that are reflected in various biomarkers of exposure, including benzene in exhaled breath, benzene in blood and urinary trans-trans-muconic acid and S-phenylmercapturic acid. A review of the literature indicates that these biomarkers can be used to distinguish populations with different levels of exposure (such as smokers from nonsmokers and occupationally exposed from environmentally exposed populations) and to determine differences in metabolism. Biomarkers in humans have shown that the percentage of benzene metabolized by the ring-opening pathway is greater at environmental exposures than that at higher occupational exposures, a trend similar to that found in animal studies. This suggests that the dose-response curve is nonlinear; that potential different metabolic mechanisms exist at high and low doses; and that the validity of a linear extrapolation of adverse effects measured at high doses to a population exposed to lower, environmental levels of benzene is uncertain. Time-series measurements of the biomarker, exhaled breath, were used to evaluate a physiologically based pharmacokinetic (PBPK) model. Biases were identified between the PBPK model predictions and experimental data that were adequately described using an empirical compartmental model. It is suggested that a mapping of the PBPK model to a compartmental model can be done to optimize the parameters in the PBPK model to provide a future framework for developing a population physiologically based pharmacokinetic model. 44 refs., 3 figs., 1 tab.

Weisel, C.; Yu, R.; Roy, A.; Georgopoulos, P. [Environmental and Occupational Health Sciences Institute, Piscataway, NJ (United States)

1996-12-01

74

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...subsequent to discharge from bulk terminals and other exemptions specified...Media: Carbon dioxide, dry chemical, or foam. ...benzene concentration in bulk material samples was also...Laboratory Method No. 12 for Bulk Samples Analyte:...

2010-07-01

75

Low benzene content gasoline producing process  

Energy Technology Data Exchange (ETDEWEB)

A process is claimed for the production of a gasoline having a low benzene content. A catalytic reformate and a stripped liquid produced in the gas concentration unit of an fcc unit are fractionated in a dehexanizer to concentrate the benzene and C3-C4 olefins these two streams contain into a single stream. This stream is passed into an alkylation zone wherein at least some of the benzene is alkylated with the olefins. The alkylation zone effluent is stripped and recombined with C7-plus dehexanizer bottoms stream to form a gasoline product stream.

Herout, R.C.; Uitti, K.D.

1980-06-24

76

Formation mechanisms for benzene and toluene during sewage sludge incineration  

Energy Technology Data Exchange (ETDEWEB)

Air-dried sewage sludge was combusted in a laboratory furnace at different temperatures and percents stoichiometric oxygen. The concentrations of benzene and toluene in the effluent gas were determined. The quantity of benzene and toluene increased with decreasing oxygen levels. Increasing the temperature from 750 to 1000/sup 0/C caused an increase in the concentration of benzene. The temperature of maximum toluene production was 850/sup 0/C. Above that temperature toluene was thermally unstable. The fatty acids in the grease and oil fraction of the sludge were found to be the source of the benzene and toluene. Reaction mechanisms leading from the fatty acids to benzene an toluene were proposed.

Burns, L.R.

1986-01-01

77

Fermentative hydrogen production at high sulfate concentration  

Energy Technology Data Exchange (ETDEWEB)

The hydraulic retention time (HRT) effects on fermentative hydrogen production from sucrose at high sulfate concentration of 3 g-SO{sub 4}{sup 2-}/l were studied using enriched mixed-microflora in a continuously fed reactor. The tested HRTs and organic loading rate ranged from 10 to 2 h and 48 to 240 g-COD/l-day, respectively, and the operating pH was 5.5. The experimental results indicate that hydrogen production could not be inhibited under high sulfate concentration and the efficiency was HRT-dependent with a short HRT of 4 h efficiently enhanced hydrogen production. At this HRT the biogas production rate and hydrogen gas content peaked with the hydrogen yield, hydrogen production rate and specific hydrogen production rate of 4.70 mol-H{sub 2}/mol-sucrose, 874 mmol-H{sub 2}/l-day and 432 mmol-H{sub 2}/g-VSS-day, respectively. These values were 50%, 80% and 300%, respectively, higher than those reported for 12 h HRT at the same sulfate concentration. The metabolite concentration fractions were butyrate 77.3%, acetate 15.6%, ethanol 4.4% and propionate 2.0% and changed to 55%, 27.3%, 11.2% and 6.5%, respectively, at HRT 2 h. Therefore, intimate HRT control is important to obtain efficient hydrogen production. Based on a biological growth comparison, pH 5.5 was considered to be the optimal value for operating a hydrogen-producing fermenter fed on sulfate-rich substrate. (author)

Chen, Chin-Chao [Environmental Resources Laboratory, Department of Landscape Architecture, Chungchou Institute of Technology, Changhwa 51022 (China); Chen, Hong-Pin; Wu, Jou-Hsien; Lin, Chiu-Yue [BioHydrogen Laboratory, Department of Water Resource Engineering, Feng Chia University, P.O. Box 25-123, Taichung 40724 (China)

2008-03-15

78

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.

79

Systems biology of human benzene exposure  

Science.gov (United States)

Toxicogenomic studies, including genome-wide analyses of susceptibility genes (genomics), gene expression (transcriptomics), protein expression (proteomics), and epigenetic modifications (epigenomics), of human populations exposed to benzene are crucial to understanding gene-environment interactions, providing the ability to develop biomarkers of exposure, early effect and susceptibility. Comprehensive analysis of these toxicogenomic and epigenomic profiles by bioinformatics in the context of phenotypic endpoints, comprises systems biology, which has the potential to comprehensively define the mechanisms by which benzene causes leukemia. We have applied this approach to a molecular epidemiology study of workers exposed to benzene. Hematotoxicity, a significant decrease in almost all blood cell counts, was identified as a phenotypic effect of benzene that occurred even below 1ppm benzene exposure. We found a significant decrease in the formation of progenitor colonies arising from bone marrow stem cells with increasing benzene exposure, showing that progenitor cells are more sensitive to the effects of benzene than mature blood cells, likely leading to the observed hematotoxicity. Analysis of transcriptomics by microarray in the peripheral blood mononuclear cells of exposed workers, identified genes and pathways (apoptosis, immune response, and inflammatory response) altered at high (>10ppm) and low (<1ppm) benzene levels. Serum proteomics by SELDI-TOF-MS revealed proteins consistently down-regulated in exposed workers. Preliminary epigenomics data showed effects of benzene on the DNA methylation of specific genes. Genomic screens for candidate genes involved in susceptibility to benzene toxicity are being undertaken in yeast, with subsequent confirmation by RNAi in human cells, to expand upon the findings from candidate gene analyses. Data on these and future biomarkers will be used to populate a large toxicogenomics database, to which we will apply bioinformatic approaches to understand the interactions among benzene toxicity, susceptibility genes, mRNA, and DNA methylation through a systems biology approach.

Zhang, Luoping; McHale, Cliona M.; Rothman, Nathaniel; Li, Guilan; Ji, Zhiying; Vermeulen, Roel; Hubbard, Alan E.; Ren, Xuefeng; Shen, Min; Rappaport, Stephen M.; North, Matthew; Skibola, Christine F.; Yin, Songnian; Vulpe, Christopher; Chanock, Stephen J.; Smith, Martyn T.; Lan, Qing

2010-01-01

80

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

 
 
 
 
81

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

Science.gov (United States)

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

Zborowski, Krzysztof K.

2014-05-01

82

090323 Benzene SGV final  

…to be degraded last (ATSDR, 2007). Exposure assessment Occurrence in soil Most soils will contain very little, if any, benzene as a result of natural processes. Benzene is released to the soil environment through industrial discharges, waste disposal, fuel leaks or spillages (IPCS, 1993; ATSDR, 2007)…

83

090323 Benzene SGV final  

…degreasing agents; in the production of artificial leather and rubber goods and in the shoe industry. Benzene is also added to petrol to improve the octane rating (ATSDR, 2007). The European petrol quality requirements limit benzene in petrol to a maximum of one percent by volume (ECB, 2007). Annual consumption…

84

090323 Benzene SGV final  

benzene SGV SCHO0309BPQI-E-P 2 Uses as a solvent include/included: in the manufacture of products such as solvents, industrial paints, rubber cements, adhesives, paint removers and degreasing agents; in the production of artificial leather and rubber goods and in the shoe industry. Benzene is also added to…

85

Analysis of the benzene oxide-DNA adduct 7-phenylguanine by liquid chromatography-nanoelectrospray ionization-high resolution tandem mass spectrometry-parallel reaction monitoring: Application to DNA from exposed mice and humans.  

Science.gov (United States)

Benzene oxide, the initial metabolite of the human carcinogen benzene, reacts with DNA producing 7-phenylguanine (7-PhG) and other products. We developed a highly sensitive liquid chromatography-nanoelectrospray ionization-high resolution tandem mass spectrometry-parallel reaction monitoring method for the analysis of 7-PhG in DNA. Accuracy and precision of the method were established and the detection limit was about 8amol of 7-PhG injected on the column and less than 1 adduct per 10(9) nucleotides in DNA. 7-PhG was detected in calf thymus DNA reacted with 1?M to 10mM benzene oxide. The method was applied for the analysis of DNA isolated from bone marrow, lung, and liver of B6C3F1 mice treated by gavage with 50mg/kg benzene in corn oil 5 times weekly for 4weeks. 7-PhG was not detected in any of these DNA samples. The method was applied to DNA from mouse hepatocytes exposed to 100?M benzene oxide and human TK-6 lymphoblasts exposed to 100?M, 1, and 10mM benzene oxide. 7-PhG was only detected in TK-6 cell DNA from the 10mM exposure. The method was also applied to leukocyte DNA from 10 smokers and 10 nonsmokers. 7-PhG was detected in only one DNA sample, from a nonsmoker. The results of this study do not support the hypothesis that the benzene oxide-DNA adduct 7-PhG is involved in carcinogenesis by benzene. PMID:24632417

Zarth, Adam T; Cheng, Guang; Zhang, Zhaobin; Wang, Mingyao; Villalta, Peter W; Balbo, Silvia; Hecht, Stephen S

2014-05-25

86

Electrochemical oxidation of benzene on boron-doped diamond electrodes.  

Science.gov (United States)

This work presents an electrochemical investigation of the benzene oxidation process in aqueous solution on boron-doped diamond (BDD) electrodes. Additionally, in order to determine the main products generated during the oxidation process, electrolysis and high performance liquid chromatography experiments were carried out. The complete degradation of this compound was performed aiming to a further application in waste water treatment. The cyclic voltammetry studies indicate that benzene is irreversibly oxidized in acid medium (H2SO4 0.5 M) on the BDD electrode surface at 2.0 V versus Ag/AgCl in a diffusion controlled process. During the cycling, other products are generated, and a pair of peaks was observed that can be associated with the oxi-reduction of anyone of the following species: hydroquinone, benzoquinone, resorcinol or catechol. The electrolysis experiments were carried out at 2.4 and 2.5 V on the BDD electrode surface in a solution containing 1x10(-2) M of benzene (below the saturation concentration in aqueous solution), for 3 and 5 h, respectively. The main products measured were: hydroquinone, resorcinol, p-benzoquinone, catechol and phenol. The complete electrochemical benzene degradation was performed in the electrolysis experiments using a rotating BDD disc electrode (2.5 V for 5 h) and the main products detected were all measured at concentrations lower than 10(-5) M in this condition. The boron-doped diamond electrode had proved to be a valuable tool for the electrochemical degradation of the benzene, a very stable chemical compound. PMID:17126378

Oliveira, Robson T S; Salazar-Banda, Giancarlo R; Santos, Mauro C; Calegaro, Marcelo L; Miwa, Douglas W; Machado, Sergio A S; Avaca, Luis A

2007-02-01

87

High throughput analysis and capture of benzo[a]pyrene using supermacroporous poly(4-vinyl pyridine-co-divinyl benzene) cryogel matrix.  

Science.gov (United States)

A novel supermacroporous cryogel matrix, poly(4-vinyl pyridine-co-divinyl benzene) has been synthesized by free radical polymerization using 4-vinyl pyridine and divinyl benzene as monomers and poly(ethylene glycol) diacrylate as crosslinker. Hydrophobic property of such synthesized matrix allows capture of polyaromatic hydrocarbons like benzo[a]pyrene. The cryogel matrix produced is highly porous (porosity more than 80%) having large and interconnected pores in the range of 10-100 ?m that allows easy passage of particulate matter and viscous liquids. The newly synthesized cryogel minicolumns (0.5 ml; 0.9 cm dia.× 1.2 cm height) were used to develop a high throughput analysis system in a miniaturized platform (open ended 96-well microtitre plate). The performance of the cryogel columns in 96-well microtitre plate was reproducible in different wells having approximately 72% binding. This system is drainage- and leakage- protected and can be used for the easy, fast and parallel analysis of many samples. The 96-well format also allows efficient analysis of benzo[a]pyrene in the spiked sample. The cryogel matrix was then used for column chromatography, which showed that the matrix has a binding capacity of 2 ?g per ml of matrix for benzo[a]pyrene, thus providing a system for remediation/separation of benzo[a]pyrene. The chromatographic column could bind and partially separate the spiked mixture of benzo[a]pyrene and anthracene. PMID:23336940

Gupta, Ankur; Sarkar, Joyita; Kumar, Ashok

2013-02-22

88

Cementification for radioactive waste including high-concentration sodium sulfate and high-concentration radioactive nuclide  

International Nuclear Information System (INIS)

For the cementification of radioactive waste that has large concentrations of sodium sulfate and radioactive nuclide, a way of fixation for sulfate ion was studied comprising the pH control of water in contact with the cement solid, and the removal of the excess water from the cement matrix to prevent hydrogen gas generation with radiolysis. It was confirmed that the sulfate ion concentration in the contacted water with the cement solid is decreased with the formation of ettringite or barium sulfate before solidification, the pH value of the pore water in the cement solid can control less than 12.5 by the application of zeolite and a low-alkali cement such as alumina cement or fly ash mixed cement, and removal of the excess water from the cement matrix by heating is possible with aggregate addition. Consequently, radioactive waste including high-concentration sodium sulfate and high-concentration radioactive nuclide can be solidified with cementitious materials. (author)

2005-10-09

89

3H-benzene metabolism in rabbit bone marrow  

International Nuclear Information System (INIS)

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

1979-08-13

90

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

International Nuclear Information System (INIS)

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

1994-05-01

91

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-07-22

92

Leukemia and Benzene  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Robert Snyder

2012-01-01

93

High faecal calprotectin concentrations in newborn infants  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Background: Calprotectin, a major component of soluble cytosolic proteins in human neutrophil granulocytes, is excreted in excess in stools during inflammatory bowel disease in adults and children. Faecal calprotectin concentrations are also higher during the first year of life than in adults.

Campeotto, F.; Butel, M.; Kalach, N.; Derrieux, S.; Aubert-jacquin, C.; Barbot, L.; Francoual, C.; Dupont, C.; Kapel, N.

2004-01-01

94

Benzene monitoring at CPPI service stations  

International Nuclear Information System (INIS)

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

1996-03-01

95

Pervaporation Characteristics in Removal of Benzene from Water through Polystyrene-Poly (Dimethylsiloxane) IPN Membranes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper focuses on the effects of the PSt content of polystyrene (PSt)-poly (dimethylsiloxane) (PDMS) interpenetrateing network (IPN) polymer membranes, on the pervaporation (PV) characteristics during the removal of benzene from an aqueous solution of dilute benzene. When an aqueous solution of 0.05wt% benzene was permeated through the PSt-PDMS IPN membranes, they showed high benzene/water selectivity. Both the permeability and the benzene/water selectivity of the membranes were enhanced ...

Tadashi Uragami; Iusaku Sumida; Takashi Miyata; Tadashi Shiraiwa; Hiroshi Tamura; Tatsuo Yajima

2011-01-01

96

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

International Nuclear Information System (INIS)

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

2011-12-01

97

Measurement of concentrator solar cell efficiency at high concentration and narrow-band spectrum  

Energy Technology Data Exchange (ETDEWEB)

High efficiency of solar cells may be obtained at high concentration and narrow-band spectrum system. Difficulties are encountered in determination of the cell efficiency using narrow-band-artificial-light sources at high concentration. A method is proposed in this article for determination of the solar cell efficiency at high concentration and narrow-band spectrum. This method is based on measurement of the solar cell fill factor and the open-circuit voltage at moderate concentration and full spectrum, and based on a calculation procedure

Appelbaum, J.; Yehezkel, N. [Tel-Aviv University, Faculty of Engineering Tel-Aviv (Israel); Yogev, A. [The Weizmann Institute of Science, Rehovot (Israel)

1998-02-27

98

High-Pressure Electrochemical Oxidation of Benzene at a Lead Dioxide Electrode in Aqueous Bisulfate Solutions at 25 to 250 C.  

Science.gov (United States)

The oxidation of benzene at a lead dioxide electrode which produces predominantly benzoquinone, maleic acid, and carbon dioxide, has been investigated in aqueous NaHSO4 solutions as a function of temperature up to 250 C. An increase in the benzene concent...

A. J. Bard K. P. Johnston W. M. Flarsheim

1987-01-01

99

Air pollution monitoring in Como urban areas. Benzene  

International Nuclear Information System (INIS)

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

2001-11-01

100

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

 
 
 
 
101

Jailbreaking benzene dimers.  

Science.gov (United States)

We suggest four new benzene dimers, (C(6)H(6))(2), all featuring one or more cyclohexadiene rings trans-fused to 4- or 6-membered rings. These hypothetical dimers are 50-99 kcal/mol less stable than two benzenes, but have computed activation energies to fragmentation ?27 kcal/mol. A thorough search of potential escape routes was undertaken, through cyclobutane ring cleavage to 12-annulenes, sigmatropic 1,5-H-shifts, electrocyclic ring-openings of the 6-membered rings, and Diels-Alder dimerizations. Some channels for reaction emerge, but there is a reasonable chance that some of these new benzene dimers can be made. PMID:22536749

Rogachev, Andrey Yu; Wen, Xiao-Dong; Hoffmann, Roald

2012-05-16

102

Benzene exposure in refinery workers: ExxonMobil Joliet, Illinois, USA (1977-2006).  

Science.gov (United States)

While petroleum industry studies have indicated low benzene exposure potential for refinery workers, most provide limited data for assessing job or task-related benzene exposures. This study characterizes job and task-specific airborne benzene concentrations and variability over time for the ExxonMobil refinery in Joliet, Illinois from 1977 to 2006. A database of 2289 industrial hygiene air samples, including 1145 non-task (?180 min) personal samples and 480 task-related (<180 min) personal samples, were analyzed. Samples were grouped by operational status, job, and task. Benzene concentrations were determined for each job category and task bin, with additional analyses conducted to determine whether benzene concentrations changed over time. The results indicate that the benzene concentrations for non-task and task samples were relatively low. For all non-task samples, the arithmetic mean benzene concentration was 0.12 part per million (ppm). The most frequently sampled workers (process technicians during routine operations) had an arithmetic mean benzene concentration of 0.038 ppm. The most frequently sampled task bin (blinding and breaking) had an arithmetic mean benzene concentration of 1.0 ppm. This study provides benzene air concentration data that can be used in combination with job histories to reconstruct historical benzene exposures for workers at the Joliet Refinery over the past 30 years. PMID:20643709

Kreider, Marisa L; Unice, Ken M; Panko, Julie M; Burns, Amanda M; Paustenbach, Dennis J; Booher, Lindsay E; Gelatt, Richard H; Gaffney, Shannon H

2010-11-01

103

Microcalorimetric Studies. Thermal Decomposition and Iodination of Bis(benzene)chromium, Bis(benzene)chromium Iodide, and Some (Arene)chromium Tricarbonyls.  

Science.gov (United States)

Thermal decomposition studies, and measurements of the heats of reaction with iodine vapour of bis(benzene)chromium, bis(benzene)chromium iodide, and some (arene)chromium tricarbonyls were made by high temperature microcalorimetry. The standard enthalpies...

H. A. Skinner J. A. Connor Y. Virmani

1972-01-01

104

090323 Benzene SGV final  

…intermediate in the production of other chemicals: ethylbenzene (used to make styrene), cumene (used to make phenol and acetone), cyclohexane (used to make nylon), nitrobenzene, alkylbenzene, maleic acid anhydride and chlorinated benzenes (IPCS, 1993; ATSDR, 2007; ECB, 2007). The estimated annual production of…

105

Economical benzene emission reduction  

International Nuclear Information System (INIS)

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

1999-05-01

106

Economical benzene emission reduction  

Energy Technology Data Exchange (ETDEWEB)

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

Schuetz, R. [DualTank Corp., Calgary, AB (Canada)

1999-05-01

107

Biodegradation of Benzene.  

Science.gov (United States)

Two species of bacteria capable of degrading the aromatic hydrocarbon benzene in vivo have been isolated from soil samples that were obtained from areas which had been drenched with kerosene (JP-4), gasoline, and diesel fuel for several years. It was reas...

B. M. Agerton J. C. Cornette

1973-01-01

108

090323 Benzene SGV final  

…2007). It is slightly soluble in water but is easily miscible with most organic solvents (IPCS, 1993; ATSDR, 2007; ECB, 2007). Benzene, toluene, ethylbenzene and xylene are often referred to collectively as BTEX because they have closely related chemical structures, and have similar fate and transport…

109

090323 Benzene SGV final  

…produced is used as a chemical intermediate in the production of other chemicals: ethylbenzene (used to make styrene), cumene (used to make phenol and acetone), cyclohexane (used to make nylon), nitrobenzene, alkylbenzene, maleic acid anhydride and chlorinated benzenes (IPCS, 1993; ATSDR, 2007; ECB, 2007…

110

090323 Benzene SGV final  

…also an important industrial chemical and is produced commercially by recovery from both petroleum and coal sources and from condensate from natural gas production (ATSDR, 2007; ECB, 2007). The majority of benzene is recovered from the petrochemical and petroleum refining industries where sources include…

111

Anomalously high radon concentrations in a dwelling in Okinawa, Japan  

International Nuclear Information System (INIS)

Short-term measurements of indoor radon concentrations were made in a dwelling in Okinawa, Japan, in which high radon concentrations had been observed in a previous nationwide indoor survey. Measurements were carried out in 4 locations: the bedroom, living room and outdoors. In this study, anomalously high radon concentrations were observed in the 1st-floor bedroom and the mean radon concentration averaged about 400 Bq m-3 during the observation period, much higher than Japan's annual average of 15.5 Bq m-3. A diurnal pattern of extreme fluctuation was found. Furthermore, there was a noticeable spatial distribution of indoor radon concentrations. (author)

2009-12-01

112

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

113

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

114

Hematotoxicity and carcinogenicity of benzene.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

1989-01-01

115

090320 benzene supplementary note final  

Supplementary information for the derivation of SGV for benzene Better Regulation Science Programme Science report: SC050021 Technical Review Benzene - Supplementary information for the derivation of SGV for benzene ii The Environment Agency is the leading public body protecting and improving the…

116

Molecular dynamics study of benzene-benzene and benzene-potassium ion interactions using polarizable potential models  

Energy Technology Data Exchange (ETDEWEB)

We have constructed a polarizable potential model for benzene using molecular dynamics techniques. The atomic site polarizabilities for carbon and hydrogen were taken from the recent work of Applequist [J. Phys. Chem. 97, 6016 (1993)], which reproduced the experimental molecular polarizability of the benzene molecule very accurately. Our model describes well the available experimental data such as the structure and thermodynamic properties of liquid benzene and the equilibrium properties of the liquid/vapor interface of benzene. The lowest minimum-energy structure of the benzene dimer predicted by our model has a T-shape with a potential energy of -2.5 kcal/mol. This value agrees with the experimentally obtained value (-2.4{+-}0.4 kcal/mol), which was determined from a high-precision ionization measurement. The cyclic minimum-energy structures are found for both the benzene trimer and tetramer clusters. The computed density profile shows that the interface is not sharp at a microscopic level and has a thickness about 5 Aa at 300 K. The calculated surface tension is 25{+-}2 dyn/cm, which is in excellent agreement with the experimentally obtained value of 28 dyn/cm. The results of our model also compare well with the corresponding results for benzene obtained by Jorgensen and Severance [J. Am. Chem. Soc. 112, 4768 (1990)], who used nonpolarizable potential parameters. We also report the details of our study of K{sup +}(C{sub 6}H{sub 6}){sub n=1-6} clusters. We found that the polarization effects were quite significant in these systems. (c) 2000 American Institute of Physics.

Dang, Liem X. [P. O. Box 999 Mail Stop K8-91, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)

2000-07-01

117

Molecular dynamics study of benzene-benzene and benzene-potassium ion interactions using polarizable potential models  

International Nuclear Information System (INIS)

We have constructed a polarizable potential model for benzene using molecular dynamics techniques. The atomic site polarizabilities for carbon and hydrogen were taken from the recent work of Applequist [J. Phys. Chem. 97, 6016 (1993)], which reproduced the experimental molecular polarizability of the benzene molecule very accurately. Our model describes well the available experimental data such as the structure and thermodynamic properties of liquid benzene and the equilibrium properties of the liquid/vapor interface of benzene. The lowest minimum-energy structure of the benzene dimer predicted by our model has a T-shape with a potential energy of -2.5 kcal/mol. This value agrees with the experimentally obtained value (-2.4±0.4 kcal/mol), which was determined from a high-precision ionization measurement. The cyclic minimum-energy structures are found for both the benzene trimer and tetramer clusters. The computed density profile shows that the interface is not sharp at a microscopic level and has a thickness about 5 Aa at 300 K. The calculated surface tension is 25±2 dyn/cm, which is in excellent agreement with the experimentally obtained value of 28 dyn/cm. The results of our model also compare well with the corresponding results for benzene obtained by Jorgensen and Severance [J. Am. Chem. Soc. 112, 4768 (1990)], who used nonpolarizable potential parameters. We also report the details of our study of K+(C6H6)n=1-6 clusters. We found that the polarization effects were quite significant in these systems. (c) 2000 American Institute of Physics

2000-07-01

118

Kinetic study of saccharomyces strains: performance at high sugar concentrations  

Energy Technology Data Exchange (ETDEWEB)

Alcoholic fermentation represents a significant example of production of compounds utilizable as alternative energy sources. High ethanol concentration in the fermented wort is needed in order to reduce the energy consumption in the process of alcohol recovery. A particular Saccharomyces strain, of the oviformis species, obtained from fermented worts exhibiting high ethanol concentrations is studied and compared with a common S. cerevisiae strain in order to show its skill in fermenting very concentrated sugar solutions with an energy saving of ca. 10%.

Converti, A.; Perego, P.; Lodi, A.; Parisi, F.; Del Borghi, M.

1985-08-01

119

Effects of high CO2 concentrations on ecophysiologically different microorganisms  

International Nuclear Information System (INIS)

We investigated the effect of increasing CO2 concentrations on the growth and viability of ecophysiologically different microorganisms to obtain information for a leakage scenario of CO2 into shallow aquifers related to the capture and storage of CO2 in deep geological sections. CO2 concentrations in the gas phase varied between atmospheric conditions and 80% CO2 for the aerobic strains Pseudomonas putida F1 and Bacillus subtilis 168 and up to 100% CO2 for the anaerobic strains Thauera aromatica K172 and Desulfovibrio vulgaris Hildenborough. Increased CO2 concentrations caused prolonged lag-phases, and reduced growth rates and cell yields; the extent of this effect was proportional to the CO2 concentration. Additional experiments with increasing CO2 concentrations and increasing pressure (1–5000 kPa) simulated situations occurring in deep CO2 storage sites. Living cell numbers decreased significantly within 24 h at pressures ?1000 kPa, demonstrating a severe lethal effect for the combination of high pressure and CO2. - Highlights: ? Influence of high CO2 concentration on ecophysiologically different (aerobic, nitrate-reducing, sulphate-reducing) microorganisms. ? Investigation of growth and viability of two aerobic and two anaerobic model organisms. ? CO2 treatment also at elevated pressure up to 5000 kPa. ? Reduction of growth and viability at high CO2 concentrations. ? Sterilization at high pressure and high CO2 concentrations. - Increased CO2 concentrations, combined also with high pressure, adversely affected the growth and viability of four ecophysiological different microorganisms.

2012-10-01

120

Benzene in Canadian gasoline : effect of the benzene in gasoline regulations : 2008 annual report  

Energy Technology Data Exchange (ETDEWEB)

The benzene in gasoline regulations came into effect on July 1st, 1999. Recommendations were first presented in 1995 to the federal government to reduce benzene in gasoline to 1 percent by volume and to maintain aromatics at 1994 levels. This report presented a review of how primary suppliers have responded to the benzene in gasoline regulations of the Canadian Environmental Protection Act of 1999 and summarized the information on composition of gasoline reported under the regulations for 2008. The report provided an overview of benzene in gasoline regulations and discussed the alternative limits for the benzene emissions number (BEN). Compliance with the regulations in terms of primary suppliers and the options to meet requirements were discussed along with information reported, reported exceedances of regulated limits and a summary of 2008 independent audits. Canadian gasoline composition was discussed in terms of volume of gasoline; regulated parameters of benzene and BEN; reported oxygen concentration; trends of aromatics and olefins; and a comparison of imported versus domestic gasoline. Other gasoline quality information was also provided. 13 tabs., 18 figs., 4 appendices.

Rahumathulla, R. [Environment Canada, Gatineau, PQ (Canada). Energy and Transportation Directorate, Oil, Gas and Alternative Energy Div.; Cober, N.; Boyce, J. [Waterloo Univ., ON (Canada)

2010-08-15

 
 
 
 
121

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

Science.gov (United States)

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

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

122

Leukemia risk associated with benzene exposure in the Pliofilm cohort  

Energy Technology Data Exchange (ETDEWEB)

A reanalysis of the Pliofilm cohort was conducted incorporating six additional years of follow-up information gathered by the National Institute of Occupational Safety and Health (NIOSH) and a new set of exposure estimates developed recently. The distribution of individual worker exposures calculated with the Paustenbach exposure estimates was compared to those derived using two earlier sets of job-, plant-, and year-specific exposure estimates. A traditional standardized mortality ratio analysis and the Cox proportional hazards model were used to investigate the impact of these exposure estimates and the NIOSH updated information on evaluation of benzene`s leukemogenicity. There were no additional cases of multiple myeloma or any indication of increased incidences of solid tumors. The data added in the update did not greatly modify the estimated relative risk of all leukemias associated with benzene exposure but confirmed previous findings that occupational exposure only to very high concentrations had leukemogenic potential. Leukemia has not been observed in anyone who began employment in Pliofilm production after 1950. Neither the Paustenbach nor the Crump exposures gave dose-response estimates as steep as that resulting from the Rinsky exposures. 16 refs., 3 figs., 8 tabs.

Paxton, M.B. [American Petroleum Institute, Washington, DC (United States)

1996-12-01

123

Decreased benzene evaporative emission from an oxygenated fuel  

Energy Technology Data Exchange (ETDEWEB)

A chromatographic head-space analysis was developed to determine the vapor phase concentrations of non-oxygenated and oxygenated fuels. The effect of ether oxygenates on benzene evaporative emissions was evaluated. A base fuel and three oxygenated fuels were prepared to contain 1 volume percent benzene at matched volatility levels. Head-space composition for each blend was measured, as a function of temperature, to determine the effects of oxygenates on benzene volatility. Results indicate MTBE (methyl tert-butyl ether), ETBE (ethyl tert-butyl ether), and TAME (tert-amyl methyl ether) each reduce benzene vapor phase concentrations. Benzene reductions averaged approximately 14 percent for fuels containing 2.7 weight percent oxygen. Reductions were temperature dependent, but not generally dependent upon type of ether oxygenate. Significant environmental benefits result from reducing benzene volatility and the resulting decrease in evaporative emissions. Benzene is classified by the EPA as a known human carcinogen. The 1990 Clean Air Act Amendments require reductions in gasoline benzene levels to reduce toxic emissions.

Bobro, C.H.; Karas, L.J.; Leaseburge, C.D.; Skahan, D.J. [ARCO Chemical CO., Newton Square, PA (United States)

1994-12-31

124

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

International Nuclear Information System (INIS)

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

2014-04-01

125

Seasonal changes of radon concentration where building material of high radon concentration were used  

International Nuclear Information System (INIS)

The majority of radiation exposure of natural origin of the population comes from radon. The primary source of radon accumulated in the buildings is the soil. Materials of high radium-content have been used at construction works in several countries. These may also act as considerable radon sources. Slag generated during the burning of coals (mined in Ajka, Tatabánya) of high radon-content has been used in several settlements as filling or insulating materials. Besides the increase of gamma dose rate in the building it also resulted in the increase of radon concentration. During our work the gamma dose rate has been surveyed in almost 100 flats in Ajka, and the quarterly average radon concentration has been measured for one year. The value of average radon concentration was measured in 20 flats monthly. In some cases samples could be taken from the slag built in, the 226Ra concentration of which was between 400 and 1500 Bq/kg. Based on the measured gamma dose rate and radon concentration values it can be stated that when slag of higher radium concentration was built in, higher radon concentration values were generated in the buildings. In one third of the buildings the annual radon concentration exceeded the value 200 Bq/m3. Based on the seasonal changes of radon concentration it could be stated that in case of building materials of high radium concentration the seasonal changes were not following the trend found by radon escaping from the soil. In these flats relatively higher radon concentration values should be taken into account even during hotter summer months. (author)

2010-01-01

126

Hair and toenail arsenic concentrations of residents living in areas with high environmental arsenic concentrations.  

Science.gov (United States)

Surface soil and groundwater in Australia have been found to contain high concentrations of arsenic. The relative importance of long-term human exposure to these sources has not been established. Several studies have investigated long-term exposure to environmental arsenic concentrations using hair and toenails as the measure of exposure. Few have compared the difference in these measures of environmental sources of exposure. In this study we aimed to investigate risk factors for elevated hair and toenail arsenic concentrations in populations exposed to a range of environmental arsenic concentrations in both drinking water and soil as well as in a control population with low arsenic concentrations in both drinking water and soil. In this study, we recruited 153 participants from areas with elevated arsenic concentrations in drinking water and residential soil, as well as a control population with no anticipated arsenic exposures. The median drinking water arsenic concentrations in the exposed population were 43.8 micro g/L (range, 16.0-73 micro g/L) and median soil arsenic concentrations were 92.0 mg/kg (range, 9.1-9,900 mg/kg). In the control group, the median drinking water arsenic concentration was below the limit of detection, and the median soil arsenic concentration was 3.3 mg/kg. Participants were categorized based on household drinking water and residential soil arsenic concentrations. The geometric mean hair arsenic concentrations were 5.52 mg/kg for the drinking water exposure group and 3.31 mg/kg for the soil exposure group. The geometric mean toenail arsenic concentrations were 21.7 mg/kg for the drinking water exposure group and 32.1 mg/kg for the high-soil exposure group. Toenail arsenic concentrations were more strongly correlated with both drinking water and soil arsenic concentrations; however, there is a strong likelihood of significant external contamination. Measures of residential exposure were better predictors of hair and toenail arsenic concentrations than were local environmental concentrations.

Hinwood, Andrea L; Sim, Malcolm R; Jolley, Damien; de Klerk, Nick; Bastone, Elisa B; Gerostamoulos, Jim; Drummer, Olaf H

2003-01-01

127

Possible genotoxicity in low level benzene exposure.  

Science.gov (United States)

Structural chromosome aberrations and sister chromatid exchanges (SCEs) in peripheral blood were studied in female workers employed in the shoe-making industry in two periods: 1987 (group I; N = 38) and 1992 (group II; N = 45). Only 11 of the workers were present in both groups and their results are presented both together and separately. Occupational exposure to benzene and toluene was confirmed through their determination in the working area, blood, and phenol in pre- and post-shift urine. The results were compared with those from the control group (N = 35). Benzene in the working atmosphere was significantly higher in 1987 compared to 1992, but was always lower than the current Croatian permissible concentration of 50 mg m-3 (in the near future this value will be changed to 15 mg m-3). A statistically significant difference was also found in biological markers of benzene exposure between the two periods of the investigation. Increased absorption in the first period occurred because of intensified production in 1987, and this decreased significantly in 1992 because of the war in Croatia. The cytogenetic study showed a significant increase in dicentric chromosomes in exposed groups I and II when compared to the control group. Statistically significant higher SCE frequencies were found in group I compared to the control group and also compared to group II. Between exposed group II and the controls no statistically significant difference in SCEs was found. Comparing the same 11 workers present in both periods the results showed no difference in chromosome aberrations between the two periods of examination. SCE frequencies were significantly higher in 1987 when greater benzene absorption occurred, confirmed by biomarkers of benzene exposure. The presented results indicate that genotoxicity may occur in workers exposed to low levels of benzene in the shoe industry. PMID:7747744

Karaci?, V; Skender, L; Bosner-Cucanci?, B; Bogadi-Sare, A

1995-03-01

128

Multijunction Photovoltaic Technologies for High-Performance Concentrators  

Energy Technology Data Exchange (ETDEWEB)

Multijunction solar cells provide high-performance technology pathways leading to potentially low-cost electricity generated from concentrated sunlight. The National Center for Photovoltaics at the National Renewable Energy Laboratory has funded different III-V multijunction solar cell technologies and various solar concentration approaches. Within this group of projects, III-V solar cell efficiencies of 41% are close at hand and will likely be reported in these conference proceedings. Companies with well-developed solar concentrator structures foresee installed system costs of $3/watt--half of today's costs--within the next 2 to 5 years as these high-efficiency photovoltaic technologies are incorporated into their concentrator photovoltaic systems. These technology improvements are timely as new large-scale multi-megawatt markets, appropriate for high performance PV concentrators, open around the world.

McConnell, R.; Symko-Davies, M.

2006-01-01

129

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-05-01

130

Highly accurate boronimeter assay of concentrated boric acid solutions  

International Nuclear Information System (INIS)

The Random-Walk Boronimeter has successfully been used as an on-line indicator of boric acid concentration in an operating commercial pressurized water reactor. The principle has been adapted for measurement of discrete samples to high accuracy and to concentrations up to 6000 ppm natural boron in light water. Boric acid concentration in an aqueous solution is a necessary measurement in many nuclear power plants, particularly those that use boric acid dissolved in the reactor coolant as a reactivity control system. Other nuclear plants use a high-concentration boric acid solution as a backup shutdown system. Such a shutdown system depends on rapid injection of the solution and frequent surveillance of the fluid to ensure the presence of the neutron absorber. The two methods typically used to measure boric acid are the chemical and the physical methods. The chemical method uses titration to determine the ionic concentration of the BO3 ions and infers the boron concentration. The physical method uses the attenuation of neutrons by the solution and infers the boron concentration from the neutron absorption properties. This paper describes the Random-Walk Boronimeter configured to measure discrete samples to high accuracy and high concentration

1992-11-15

131

High concentration photovoltaic systems applying III-V cells  

Energy Technology Data Exchange (ETDEWEB)

High concentration systems make use of the direct solar beam and therefore are suitable for application in regions with high annual direct irradiation values. III-V PV cells with a nominal efficiency of up to 39% are readily available in today's market, with further efficiency improvements expected in the years ahead. The relatively high cost of III-V cells limits their terrestrial use to applications under high concentration, usually above 400 suns. In this way the relatively high cell cost is compensated through the low amount for cells needed per kW nominal system output. This paper presents a state of the art of high concentration photovoltaics using III-V cells. This PV field accounts already for more than 20 developed systems, which are commercially available or shortly before market introduction. (author)

Zubi, Ghassan; Bernal-Agustin, Jose L. [Department of Electrical Engineering, University of Zaragoza, Calle Maria de Luna 3, 50018 Zaragoza (Spain); Fracastoro, Gian Vincenzo [Department of Energetics, Politecnico of Turin, Corso Duca degli Abruzzi 24, 10129 Torino (Italy)

2009-12-15

132

Hair and toenail arsenic concentrations of residents living in areas with high environmental arsenic concentrations.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Surface soil and groundwater in Australia have been found to contain high concentrations of arsenic. The relative importance of long-term human exposure to these sources has not been established. Several studies have investigated long-term exposure to environmental arsenic concentrations using hair and toenails as the measure of exposure. Few have compared the difference in these measures of environmental sources of exposure. In this study we aimed to investigate risk factors for elevated hai...

Hinwood, Andrea L.; Sim, Malcolm R.; Jolley, Damien; Klerk, Nick; Bastone, Elisa B.; Gerostamoulos, Jim; Drummer, Olaf H.

2003-01-01

133

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

134

Inhibition of chlorophyll synthesis by high concentrations of carbon dioxide  

Energy Technology Data Exchange (ETDEWEB)

High concentrations of carbon dioxide inhibit the greening of etiolated plants. In the presence of 20% oxygen, concentrations of carbon dioxide of 10% and above inhibited the production of chlorophyll in etiolated leaves of barley, wheat, and dwarf French bean. On return to air, recovery from this inhibition took place rapidly. High concentrations of carbon dioxide were also inhibitory when illumination was discontinuous (2-msecond flash separated by 3-minute dark period) during which photosynthetic activity was adjudged to be negligible. The inhibition was alleviated by feeding with delta-amino levulinic aid, implying that the site of inhibition was early in the sequence of chlorophyll synthesis. 15 references, 3 figures, 1 table.

Steer, B.T.; Walker, D.A.

1964-01-01

135

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

136

Optical design of stationary solar concentrators for high latitudes  

Energy Technology Data Exchange (ETDEWEB)

The optical design of stationary solar concentrators for high latitudes has been studied. Irradiation distribution diagrams, which are tools for the design of stationary linear concentrators, have been developed. The annual irradiation distribution in a north-south vertical plane is asymmetric at high latitudes due to reduced irradiation during the winter. This implies that asymmetrical concentrators are attractive for high latitudes, that a large optimum collector tilt is required and that the degree of concentration can be relatively high, compared to low latitude sites. Planar booster reflectors for solar cell modules and corrugated booster reflectors for solar collectors are suggested as two promising techniques for increasing the annual performance. Collector heat losses were studied in a CPC (Compound Parabolic Concentrator) collector model. It was found that low thermal emittance of the reflectors and the use of transparent insulation, such as teflon films, in the collector decrease the collector heat losses. The low heat loss in CPC collectors is demonstrated in a study of a 13.6 m{sup 2} CPC collector with a concentration ratio of 1.53, which showed 25% lower heat loss coefficient compared to an equivalent flat plate collector. The complex incidence angle performance of a low-concentrating CPC with flat absorber was investigated. The result indicates that the use of factorized incidence angle modifiers will overestimate the annual delivered energy by about 4-5%. The optical performance of CPCs will change if the reflectors are equipped with linear corrugations since this will increase the acceptance of radiation in the meridian plane. This is less desirable for stationary concentrators but make these concentrators interesting as secondary concentrators for two-axis tracking parabolic troughs 85 refs, 47 figs, 1 tab

Roennelid, Mats

1998-12-31

137

Electron beam treatment of exhaust gas with high NOx concentration  

Science.gov (United States)

Simulated exhaust gases with a high NOx concentration, ranging from 200 to 1700 ppmv, were irradiated by an electron beam from an accelerator. In the first part of this study, only exhaust gases were treated. Low NOx removal efficiencies were obtained for high NOx concentrations, even with high irradiation doses applied. In the second part of study, gaseous ammonia or/and vapor ethanol were added to the exhaust gas before its inlet to the plasma reactor. These additions significantly enhanced the NOx removal efficiency. The synergistic effect of high SO2 concentration on NOx removal was observed. The combination of electron beam treatment with the introduction of the above additions and with the performance of irradiation under optimal parameters ensured high NOx removal efficiency without the application of a solid-state catalyst.

Licki, Janusz; Chmielewski, Andrzej G.; Pawelec, Andrzej; Zimek, Zbigniew; Witman, Sylwia

2014-05-01

138

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

1993-01-01

139

BICON: high concentration PV using one-axis tracking and silicon concentrator cells  

Energy Technology Data Exchange (ETDEWEB)

BICON is a two-stage concentrator system developed at Fraunhofer ISE which is one-axis tracked. The innovation of this one-axis tracked system is that it enables a high geometrical concentration of 300 x in combination with a high optical efficiency (up to 78%) and a large acceptance angle of {+-} 23.5{sup o} all year through. For this, the system uses a parabolic mirror (40.4 x) and a three dimensional second stage consisting of compound parabolic concentrators (CPCs, 7.7 x). For the concentrator concept and particularly for an easy cell integration, rear-line-contacted concentrator (RLCC) cells with a maximum efficiency of 25% were developed and a hybrid mounting concept for the RLCC cells is presented. The optical performance of different CPC materials was tested and is analysed in this paper. Finally, small modules consisting of six series interconnected RLCC cells and six CPCs were integrated into the concentrator system and tested outdoor. A BICON system efficiency of 16.2% was reached at around 800 W/m{sup 2} direct irradiance under realistic outdoor conditions. (author)

Mohr, A.; Roth, T.; Glunz, S.W. [Fraunhofer Instritut fuer Solare Energiesysteme, Freiburg (Germany)

2006-07-01

140

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.

2013-03-22

 
 
 
 
141

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

Science.gov (United States)

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.

Ge, H.; Yu, R.; Mi, D.; Zhu, Y. M.

2013-03-01

142

Concentration of High Level Radioactive Liquid Waste. Basic data acquisition  

Energy Technology Data Exchange (ETDEWEB)

Full text of publication follows: In order to enhance its knowledge about the concentration of high level liquid waste (HLLW) from the nuclear fuel reprocessing process, a program of studies was defined by Cea. In a large field of acidity, it proposes to characterize the concentrated solution and the obtained precipitates versus the concentration factor. Four steps are considered: quantification of the salting-out effect on the concentrate acidity, acquisition of solubility data, precipitates characterisation versus the concentration factor through aging tests and concentration experimentation starting from simulated fission products solutions. The first results, reported here, connect the acidity of the concentrated solution to the concentration factor and allow us to precise the field of acidity (4 to 12 N) for the next experiments. In this field, solubility data of various elements (Ba, Sr, Zr...) are separately measured at room temperature, in nitric acid in a first time, then in the presence of various species present in medium (TBP, PO{sub 4}{sup 3-}). The reactions between these various elements are then investigated (formation of insoluble mixed compounds) by following the concentration cations in solution and characterising the precipitates. (authors)

Juvenelle, A.; Masson, M.; Garrido, M.H. [DEN/VRH/DRCP/SCPS/LPCP, BP 17171 - 30207 Bagnols sur Ceze Cedex (France)

2008-07-01

143

Concentration of High Level Radioactive Liquid Waste. Basic data acquisition  

International Nuclear Information System (INIS)

Full text of publication follows: In order to enhance its knowledge about the concentration of high level liquid waste (HLLW) from the nuclear fuel reprocessing process, a program of studies was defined by Cea. In a large field of acidity, it proposes to characterize the concentrated solution and the obtained precipitates versus the concentration factor. Four steps are considered: quantification of the salting-out effect on the concentrate acidity, acquisition of solubility data, precipitates characterisation versus the concentration factor through aging tests and concentration experimentation starting from simulated fission products solutions. The first results, reported here, connect the acidity of the concentrated solution to the concentration factor and allow us to precise the field of acidity (4 to 12 N) for the next experiments. In this field, solubility data of various elements (Ba, Sr, Zr...) are separately measured at room temperature, in nitric acid in a first time, then in the presence of various species present in medium (TBP, PO43-). The reactions between these various elements are then investigated (formation of insoluble mixed compounds) by following the concentration cations in solution and characterising the precipitates. (authors)

2008-05-19

144

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)

2011-02-01

145

Environmental exposure to benzene: an update.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

During the 1990s, several large-scale studies of benzene concentrations in air, food, and blood have added to our knowledge of its environmental occurrence. In general, the new studies have confirmed the earlier findings of the U.S. Environmental Protection Agency Total Exposure Assessment Methodology (TEAM) studies and other large-scale studies in Germany and the Netherlands concerning the levels of exposure and major sources. For example, the new studies found that personal exposures exceed...

1996-01-01

146

High Nitrate Concentrations in Vacuolate, Autotrophic Marine Beggiatoa spp  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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, an...

1996-01-01

147

Mobil-Badger technologies for benzene reduction in gasoline  

Energy Technology Data Exchange (ETDEWEB)

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

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

1993-01-01

148

Benzene exposure: An overview of monitoring methods and their findings  

Science.gov (United States)

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

Weisel, Clifford P.

2014-01-01

149

Dissolution of irradiated MOX fuel for highly concentrated solution  

International Nuclear Information System (INIS)

Dissolution behavior of the irradiated MOX fuel was investigated under high Heavy Metal (HM, U+Pu) concentration condition (final [HM]([HM]f) ? 600 g/l) for the feed solution of the crystallization process. The calculation code based on the fragmentation model was developed by analyzing the past dissolution trial data obtained mainly under low final HM concentration condition ([HM]f sol/Vpieces) (under high [MH]f), and this could be improved drastically by changing the fuel form from the sheared fuel pieces to the powdered fuel. The hot dissolution trials using the fast reactor 'JOYO' Mk-II irradiated MOX sheared fuel pieces and powdered fuel were carried out based on this calculation, and confirmed the advantage of the powdered fuel dissolution for highly concentrated solution and the effectiveness of the calculation code with the fragmentation model on the estimation of the fuel dissolution behavior. (author)

2005-10-09

150

Dilute acid pretreatment of biomass at high acid concentrations  

Energy Technology Data Exchange (ETDEWEB)

The dilute acid pretreatment of biomass (aspen wood and wheat straw) at high solids concentrations (up to 40 weight percent) has been investigated. It produces a concentrated monomeric soluble sugar stream (mainly xylose) with little degradation of the available sugars and a solid residue containing cellulose and lignin. The cellulose remaining in the residue from both aspen and straw pretreated at either 140 degrees or 160 degrees was highly digestible with commercial available enzymes. A somewhat higher acid consumption for wheat straw compared with that for aspen can be alleviated by a cation-removal step.

Grohmann, K.; Torget, R.; Himmel, M.; Scott, C.D. (ed.)

1986-01-01

151

BTEX [benzene, toluene, ethyl benzene, xylene] control via biofiltration  

Energy Technology Data Exchange (ETDEWEB)

In the use of biofiltration for controlling air pollution problems, the polluted air is conditioned and then passed through a filter, usually ca 1 m thick, composed of a variety of organic and inorganic materials, where naturally occurring and/or inoculated microorganisms break down the offending compounds, releasing clean air plus harmless and odor-free compounds to the atmosphere. One of the main areas of interest for applying biofiltration in North America has been for site remediation of soils contaminated with hydrocarbons, particularly benzene, toluene, ethyl benzene, and xylene (BTEX) associated with gasoline spills. The Ambio Biofiltration biofilter, which is compost-based, has had its first commercial application at a gas station in Quebec, on the end of a soil vapor extraction system. The soil under the station was found to have high BTEX levels, so wells were drilled at the site and a vapor extraction system was installed. Total air flow from the system is ca 50 ft[sup 3]/min, which is easily handled by the Ambio system. The biofilters have removed over 90% of total BTEX (86-98% for individual compounds) and after several months of operation, emission levels are lower than the detection limit of ca 0.5 ppM. Cost of the system is ca $20-30/kg of total BTEX treated. The Ambio unit is compact and has had no problem operating in the middle of one of the coldest winters on record. Infrastructure requirements for the Ambio system are simple and filter life should be in excess of five years. 2 figs.

Pride, C

1994-08-01

152

090320 benzene supplementary note final  

…Technical Review Benzene - Supplementary information for the derivation of SGV for benzene ii The Environment Agency is the leading public body protecting and improving the environment in England and Wales. It's our job to make sure that air, land and water are looked after by everyone in today's society…

153

090320 benzene supplementary note final  

…Better Regulation Science Programme Science report: SC050021 Technical Review Benzene - Supplementary information for the derivation of SGV for benzene ii The Environment Agency is the leading public body protecting and improving the environment in England and Wales. It's our job to make sure that air,…

154

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

155

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; Tonboe, R.

2007-01-01

156

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

International Nuclear Information System (INIS)

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

2011-11-15

157

Acclimation and toxicity of high ammonium concentrations to unicellular algae.  

Science.gov (United States)

A literature review on the effects of high ammonium concentrations on the growth of 6 classes of microalgae suggests the following rankings. Mean optimal ammonium concentrations were 7600, 2500, 1400, 340, 260, 100 ?M for Chlorophyceae, Cyanophyceae, Prymnesiophyceae, Diatomophyceae, Raphidophyceae, and Dinophyceae respectively and their tolerance to high toxic ammonium levels was 39,000, 13,000, 2300, 3600, 2500, 1200 ?M respectively. Field ammonium concentrations diatoms, prymnesiophytes, dinoflagellates, and raphidophytes. Cyanophytes were significantly more tolerant than dinoflagellates which were the least tolerant. A smaller but more complete data set was used to estimate ammonium EC?? values, and the ranking was: Chlorophyceae>Cyanophyceae, Dinophyceae, Diatomophyceae, and Raphidophyceae. Ammonia toxicity is mainly attributed to NH? at pHs >9 and at pHs <8, toxicity is likely associated with the ammonium ion rather than ammonia. PMID:24533997

Collos, Yves; Harrison, Paul J

2014-03-15

158

[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

159

Linear and nonlinear optical properties of highly concentrated gold nanoparticles  

Science.gov (United States)

Linear and nonlinear (NL) optical properties of composite materials containing high concentration of gold nanoparticles (NPs) were studied using the Maxwell-Garnett model and the degenerated electron gas model. High values of the linear refraction index of the composite, NL shift of the plasmon resonance peak and reversal sign of the real and imaginary parts of the NL third-order susceptibility were observed. Figures of merit for photonic devices were calculated and fulfilled depending of the filling factor and NPs size.

Damasceno, Andrey R. P.; Gómez-Malagón, Luis A.

2013-08-01

160

Process for producing high-concentration slurry of coal  

Energy Technology Data Exchange (ETDEWEB)

High concentrated coal-water slurry is produced by coarsely crushing coal, thereafter pulverizing the coarsely crushed coal, together with water and a slurry dispersant, according to necessity, in a wet-type ball mill, and feeding back one portion of the finely pulverized coal slurry thus obtained into the inlet of the wet-type ball mill.

Nakaoji, K.; Itoh, H.; Kamao, M.; Takao, Sh.; Tatsumi, Sh.

1985-02-19

 
 
 
 
161

Urban benzene pollution and population exposure  

Energy Technology Data Exchange (ETDEWEB)

Benzene is among the gasoline components and is airborne by vehicular traffic. It is a myelo-toxic and leukaemia-inducing compound. The risk level, expressed as myeloid leukaemia cases increment estimate among the population not professionally exposed to benzene, has been stated to range 3.8 to 7.5 cases every million people exposed during the lifetime to 1 {mu}g/m{sup 3}. All the estimates deal with exposure, not with environmental concentration. Since the two parameters can be not coincident, the citizens' risk level, which depends on actual exposure, can not be simply estimated by means of urban pollution. Therefore, once a socially acceptable exposure risk level is stated by a political decision, one can set a limiting value for benzene concentration in urban air only if the relationship between personal exposure and urban pollution is known. We find the citizens' exposure level, whatever their occupation or the fraction of time spent outdoors, is higher than urban average level and is equal, on average in Europe, to twice its value. To establish this relationship, six towns and a sample of their citizens and their homes have undergone environmental monitoring for an entire year. The towns were distributed among the Northern, Central and Southern European countries, comprising a wide range of different lifestyles, climates and development features. (authors)

Cocheo, V.; Sacco, P.; Boaretto, C. [Fondazione Salvatore, Maugeri-IRCCS, Padova (Italy); Saeger, E. de; Ballesta, P.P. [Joint Research Centre, Ispra (Italy); Skov, H. [National Environmental Research Institute, Frederiksborgvej (Denmark); Goelen, E. [Vlaamse Instelling voor Technologisch Onderzoek, Mol (Belgium); Gonzalez, N. [Institut National de l' environnement Industriel et des Risques, 60 - Verneuil en Halatte (France); Caracena, A.B. [Universidad de Murcia, Dept. de Ingenieria Quimica-Murcia (Spain)

2001-07-01

162

[Toxic effects of high concentrations of ammonia on Euglena gracilis].  

Science.gov (United States)

Ammonia is among the common contaminants in aquatic environments. The present study aimed at evaluation of the toxicity of ammonia at high concentration by detecting its effects on the growth, pigment contents, antioxidant enzyme activities, and DNA damage (comet assay) of a unicellular microalga, Euglena gracilis. Ammonia restrained the growth of E. gracilis, while at higher concentrations, ammonia showed notable inhibition effect, the growth at 2 000 mg x L(-1) was restrained to 55.7% compared with that of the control; The contents of photosynthetic pigments and protein went up with increasing ammonia dosage and decreased when the ammonia concentration was above 1000 mg x L(-1); In addition, there was an obvious increase in SOD and POD activities, at higher concentration (2 000 mg x L(-1)), activities of SOD and POD increased by 30.7% and 49.4% compared with those of the control, indicating that ammonia could promote activities of antioxidant enzymes in E. gracilis; The degree of DNA damage observed in the comet assay increased with increasing ammonia concentration, which suggested that high dose of ammonia may have potential mutagenicity on E. gracilis. PMID:24455949

Liu, Yan; Shi, Xiao-Rong; Cui, Yi-Bin; Li, Mei

2013-11-01

163

Ambient air levels and occupational exposure to benzene, toluene, and xylenes in northwestern Italy.  

Science.gov (United States)

The purpose of this study was to determine benzene, toluene, and xylenes air pollution in two cities in Italy (Biella and Torino) having different traffic intesities and to investigate whether new environmental conditions occurred consequent to the changes of gasoline composition in Europe during the last 20 yr. Furthermore, three types of urban occupational exposure (petrol pump attendants, traffic policemen, and municipal employees) to the same hydrocarbons were compared to verify three different expected levels of exposure. Results in Biella demonstrate a direct relationship between traffic density and level of human exposure to these pollutants. Air concentrations for benzene were 2.3 micrograms/m3 in a suburban area having low traffic and 10.3 micrograms/m3 in the central area having high traffic. The comparison to trend analysis recently carried out in Torino indicates it is possible to improve the situation in the central area of Biella by adopting the same traffic limitations imposed in Torino. Personal sampling devices demonstrated that only the petrol pump attendants show, by means of a multivariate analysis, statistically significant higher levels of benzene compared to the other two professional categories, in both winter and summer. Values found in the present study for petrol pump attendants were around 1 mg/m3. Environmental and occupational exposure to benzene, toluene, and xylenes could be largely lowered by adopting preventive measures including traffic restrictions, the reduction of aromatic chemical content in gasoline, and the recovery of gasoline vapors at petrol pump stations. PMID:12712594

Bono, Roberto; Scursatone, Enzo; Schilirò, Tiziana; Gilli, Giorgio

2003-03-28

164

Unusually high indoor radon concentrations from a giant rock slide.  

Science.gov (United States)

In a village in western Tyrol, Austria (Umhausen, approximately 2600 inhabitants) unusually high indoor radon concentrations were measured. The medians were found to be 3750 Bq/m3 (basements) and 1160 Bq/m3 (ground floors) in winter, and 361 Bq/m3 (basements) and 210 Bq/m3 (ground floors) in summer. Maximum radon concentrations of up to 274,000 Bq/m3 were registered. The unusually high radon concentrations are due to the geology of the locality. The part of Umhausen with the highest radon concentrations is built on an alluvial fan of a giant rock slide (granitic gneiss). Measurements of the radon exhalation rate from soil showed a median of 0.4 Bq/m2/s, measurements of the radium content of rock samples yielded a median of 125 Bq/kg. The material of the rock slide is heavily fractured so that an elevated emanating power and an increased diffusion coefficient for radon in soil must be assumed. Given a diffusion coefficient of 8 x 10(-6) m2/s and an emanating power of 0.3, the median exhalation rate of 0.4 Bq/m2/s is obtained at a radium concentration of 125 Bq/kg. The rock slide is therefore considered to be the main source of radon. The abnormally high radon concentrations in Umhausen coincide with a statistically significant increase in lung cancer mortality (age and sex standardized mortality rate = 3.9, 95% C.I.: 2.9-5.1); the control population is the population of the entire Tyrol (630,000 inhabitants). PMID:8085147

Ennemoser, O; Ambach, W; Brunner, P; Schneider, P; Oberaigner, W; Purtscheller, F; Stingl, V; Keller, G

1994-07-18

165

High melting point metals welding by concentrated solar energy  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Sound welding of high melting point metals, namely H13 tool steel and AISI 316L stainless steel, have been achieved by means of concentrated solar energy. Longitudinal weld track on 2 and 5 mm steel sheets with a thickness up to 60 mm, under argon atmosphere, has been performed on a variety of geometrical configurations. This work has been carried out in a 2 kW thermal power vertical axis parabolic concentrator at the PROMES-CNRS Solar facility (Odeillo-Font-Romeu, southeast France). Cross se...

2013-01-01

166

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

167

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

168

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

1996-01-01

169

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

Directory of Open Access Journals (Sweden)

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

AharonOren

2013-11-01

170

Hydrated electron in irradiated highly concentrated solutions of magnesium chloride  

International Nuclear Information System (INIS)

Using the method of nanosecond pulse radiolysis the yields (G) and kinetics of hydrated electron (HE) reactions in 0.5-4.8 mol/dm3 aqueous solutions of MgCl2 at the temperatures from 298 to 393 K are investigated. It is shown that under the conditions GHE=2.7±0.3 electron/100 eV. Disappearance of HE at high concentrations of solution takes place in the reaction with Mg (2), energetic validity of which is confirmed by quantum-chemical calculations of electron structure of Mg (2) aguacomplexes. Temperature dependence of the reaction constant rate in solutions of different concentration testifies to the fact that the constant growth with solution concentration increase is mainly determined by the change in entropy factor

1989-01-01

171

Hydrated electrons in irradiated, highly concentrated magnesium chloride solutions  

International Nuclear Information System (INIS)

The nanosecond pulse radiolysis method was used to investigate the yields and kinetics of eaq- reactions in 0.5-4.8 mole/dm3 aqueous solutions of MgCl2 in the temperature range 298-393 K. It was found that under these conditions Geaq- = 2.7 ± 0.3 electrons/100 eV. At high solution concentrations eaq- disappears in a reaction with Mg(II), the energetics of which are validated by quantum-chemical calculations of the electronic structure of Mg(II) aquo-complexes. The temperature dependence of the rate constant for this reaction in solutions of differing concentrations suggests that the rise in the constant with increasing solution concentration is determined mainly by a change in the entropy factor

1989-07-01

172

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

International Nuclear Information System (INIS)

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

2006-01-01

173

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)

2007-10-05

174

Preparation of highly concentrated nanostructured dispersions of controlled size  

DEFF Research Database (Denmark)

This article presents the use of a shearing procedure for the preparation of stable nanostructured dispersions of lipid mesophases. This new application of the shearing technique is compared with the well-established ultrasonication method for the emulsification of these mesophases in water in terms of particle size, particle size distribution and available concentration range. With a laboratory-built shear device based on a Couette cell, it was possible to produce high quantities of internally self-assembled emulsion particles of controlled size at concentrated hydrophobic phase contents (phi(o)) of up to 70 wt%. The concentration limit of 70 wt% could be reached however, the maximum attainable concentration depended on the internal structure type of the particles. The limit was thus easily attained for emulsified microemulsions (EME) as well as for the emulsified inverse hexagonal phase (H(2)), whereas it was found to be lower for emulsified discontinuous (Fd3m) and bicontinuous (Pn3m) cubic phases. Moreover, by shearing, it was possible to keep the size of the particles relatively constant when increasing phi(o), whereas the particle size significantly increased with phi(o) when ultrasonication was employed. By means of ultrasonication, the hydrodynamic radius of the particles could be tuned linearly between 85 to 180 nm as a function of phi(o) up to a maximum of 20 to 30 wt%. Below the maximum concentration limit, particles displayed a well-controlled size.

Salentinig, Stefan; Yaghmur, Anan

2008-01-01

175

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 50volume %) 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 30min the LC50 decreases hardly with increasing exposure duration. Below 30min 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

176

Highly concentrated zinc oxide nanocrystals sol with strong blue emission  

Energy Technology Data Exchange (ETDEWEB)

Highly concentrated ZnO sol was synthesized by an improved sol-gel method. Water was used as a modifier to control the sol-gel reaction and provide a way to increase the sol concentration. Concentration of ZnO in the prepared sol is higher than from other methods. Optical absorption and photoluminescence were used to investigate optical properties of the prepared sol. FTIR test was performed to study the influence of water on the compounds of as-prepared sol. The size and morphology of ZnO nanoparticles have been studied by HRTEM. The prepared colloidal ZnO nanocrystals have narrow size distribution (5-8 nm) and showed strong blue emission. The prepared sol has enough potential for optoelectronic applications. - Research highlights: {yields} Novel sol-gel route has been employed to prepare highly concentrated ZnO colloidal nanocrystals. {yields} Water has been used to control the sources of emission in synthesized material. {yields} A strong blue luminescent material has been obtained.

Vafaee, M. [Solid State Lasers Research Group, Laser and Optics Research School, NSTRI, 11365-8486 Tehran (Iran, Islamic Republic of); Sasani Ghamsari, M., E-mail: msghamsari@yahoo.co [Solid State Lasers Research Group, Laser and Optics Research School, NSTRI, 11365-8486 Tehran (Iran, Islamic Republic of); School of Applied Physics, Faculty of Science and Technology, National University of Malaysia (UKM), 43600 Bangi, Selangor (Malaysia); Radiman, S. [School of Applied Physics, Faculty of Science and Technology, National University of Malaysia (UKM), 43600 Bangi, Selangor (Malaysia)

2011-01-15

177

Highly concentrated zinc oxide nanocrystals sol with strong blue emission  

International Nuclear Information System (INIS)

Highly concentrated ZnO sol was synthesized by an improved sol-gel method. Water was used as a modifier to control the sol-gel reaction and provide a way to increase the sol concentration. Concentration of ZnO in the prepared sol is higher than from other methods. Optical absorption and photoluminescence were used to investigate optical properties of the prepared sol. FTIR test was performed to study the influence of water on the compounds of as-prepared sol. The size and morphology of ZnO nanoparticles have been studied by HRTEM. The prepared colloidal ZnO nanocrystals have narrow size distribution (5-8 nm) and showed strong blue emission. The prepared sol has enough potential for optoelectronic applications. - Research highlights: ? Novel sol-gel route has been employed to prepare highly concentrated ZnO colloidal nanocrystals. ? Water has been used to control the sources of emission in synthesized material. ? A strong blue luminescent material has been obtained.

2011-01-01

178

Investigation of high-efficiency silicon concentrator cells  

Science.gov (United States)

The high-efficiency features of silicon concentrator cells examined include reduction of heavy-doping effects through ion implantation, surface passivation, reduction of cell thickness, patterning to reduce emitter area, passivation to reduce metal/Si contact interaction area, and investigation of back junction solar cells to separate emitter patterning from grid design. This research has achieved V sub OC of 657 mV. Concentrator cell efficiency of up to 20.7% was also attained. The principal finding of this work is that thin high-efficiency designs must have adequate passivation on the front and back surfaces. Lack of passivation at the metal/Si contact interface has emerged as the limiting feature of the best cells.

1986-04-01

179

Biodegradation studies of oil sludge containing high hydrocarbons concentration  

International Nuclear Information System (INIS)

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

2008-09-00

180

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

 
 
 
 
181

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

182

Highly concentrated active nonlinear media based on oxides  

Energy Technology Data Exchange (ETDEWEB)

Important characteristics of highly concentrated active nonlinear media were studied which were based on oxide compounds of phosphates, niobates, tantalates, and titanates of neodymium with alkaline earth metals. Compounds of the indicated classes were synthesized and their spectral luminescent and nonlinear optical properties were studied. Single crystals were grown from the selected compounds (5-8mm) and preliminary measurements of the laser and nonlinear optical parameters were taken. Formulas are given for materials that demonstrated high nonlinear and luminescent properties simultaneously. Spectroscopic and nonlinear optical properties of some oxygen compounds of rare earth elements are shown.

Bakin, D.V.; Dorozhkin, L.M.; Krasilov, Yu.I.; Kuznetsov, N.T.; Potemkin, A.V.; Tadzhi-Aglaev, K.S.; Shestakov, A.V.

1987-07-01

183

Correlating benzene, total hydrocarbon and carbon monoxide emissions from wood-fired boilers  

Energy Technology Data Exchange (ETDEWEB)

Hazardous air pollutants, including benzene, are generated by the incomplete combustion of fuels. Organic compound emissions, which are generally products of incomplete combustion, are reduced by promoting high quality combustion, for example by controlling furnace exit temperatures and establishing minimum residence times. Monitoring carbon monoxide (CO) emissions is important since the amount of carbon monoxide emitted represents the quality of combustion which in turn represents the amount of hazardous air pollutants being generated. Total hydrocarbon (THC) emissions are also related to the quality of combustion. Recently the Wisconsin Department of Natural Resources (DNR) measured the benzene and total hydrocarbon emissions from two large industrial wood fired boilers. These boilers are located at Tenneco Packaging, a container board manufacturing facility in northern Wisconsin. Temperature, oxygen and carbon monoxide concentrations were sampled continuously by Tenneco Packaging`s emission monitoring system. The Department`s team used an organic vapor analyzer to continuously measure concentrations of total hydrocarbons (THC). The Department`s team also used a modified USEPA Method 18 sampling train to capture organic vapors for subsequent analysis by gas chromatography. The data show correlations between benzene and carbon monoxide, and between benzene and THC concentrations. The emissions sampling occurred both upstream of the particulate emissions control system as well as at the stack. The CO variations during actual boiler operation appeared to be well correlated with changes in boiler steam load. That is, increases in CO generally accompanied a change, either up or down, in boiler load. Lower concentrations of CO were associated with stable combustion, as indicated by periods of constant or nearly constant boiler load.

Hubbard, A.J.; Grande, D.E.; Berens, J.R. [Wisconsin Dept. of Natural Resources, Madison, WI (United States); Piotrowski, J. [Tenneco Packaging, Inc., Tomahawk, WI (United States)

1997-12-31

184

Decomposition of benzene in a corona discharge at atmospheric pressure  

International Nuclear Information System (INIS)

We investigated the decomposition characteristics of benzene in a positive DC corona discharge between multineedle and plane electrodes with a background gas of nitrogen-oxygen mixture at atmospheric pressure. We obtained C2H2, HCN, HCOOH, CO and CO2 as benzene fragments and by-products, and C2H2 and HCN as minor intermediate products. Benzene was primarily converted into CO2 via CO at low oxygen concentrations (0.2%) and via CO and HCOOH at the atmospheric oxygen concentration (20%). Further, 57% and 24% of carbon atoms were deposited on the plane electrode and the discharge chamber at oxygen concentrations of 0.2% and 20%, respectively

2008-05-01

185

Organoclay formulations of acetochlor: effect of high salt concentration.  

Science.gov (United States)

This study aimed to evaluate new methodology for designing ecologically acceptable formulations of acetochlor. Modification of montmorillonite with phenyltrimethylammonium chloride (PTMA) or benzyltrimethylammonium chloride (BTMA) and organoclay formulations of acetochlor were prepared in the presence of high concentrations of sodium chloride (150 g/L). Acetochlor concentration in the equilibrium solutions was determined by HPLC. Release of acetochlor in a water system was performed by a funnel experiment. Leaching of acetochlor in soil was determined by a bioassay using a column technique and Setaria viridis as a test plant. The adsorbed amounts of acetochlor on montmorillonite exchanged by PTMA or BTMA were increased as NaCl concentration increased in the equilibrium solution. Leaching of acetochlor from organoclay formulations was significantly inhibited to the top soil layer (0-5 cm) when the formulations were prepared at extreme NaCl concentration (100-150 g/L). These results are in accord with a funnel experiment that showed a reduction in acetochlor release from the montmorillonite-based formulations. The application of this method for herbicide formulation would produce ecologically acceptable herbicide formulations that can significantly minimize the risk to groundwater pollution. PMID:15740049

El-Nahhal, Yasser; Lagaly, Gerhard; Rabinovitz, Onn

2005-03-01

186

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)

2011-10-24

187

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

1996-01-01

188

Complete mineralization of benzene by aquifer microorganisms under strictly anaerobic conditions.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Benzene was mineralized to CO2 by aquifer-derived microorganisms under strictly anaerobic conditions. The degradation occurred in microcosms containing gasoline-contaminated subsurface sediment from Seal Beach, California, and anaerobic, sulfide-reduced defined mineral medium supplemented with 20 mM sulfate. Benzene, at initial concentrations ranging from 40 to 200 microM, was depleted in all microcosms and more than 90% of 14C-labeled benzene was mineralized to 14CO2.

Edwards, E. A.; Grbic?-galic?, D.

1992-01-01

189

Influence of benzene on the phytoplankton and on Daphnia pulex in compartments of an experimental pond  

Energy Technology Data Exchange (ETDEWEB)

Benzene, with initial concentrations of 100 and 50 mg per liter, was dosed in duplicates into four compartments of a small pond. The decrease of chemical concentration in the water was exponential with a mean half-life of 4.7 +/- 0.9 days. Following benzene application, the phytoplankton density and diversity slightly increased relative to the controls. Both concentrations were lethal for the daphnids present. During 24-hr in vitro tests with Daphnia pulex (initial benzene concentrations less than 50 mg per liter), a direct correlation between mobility and decreasing chemical concentration was observed.

Lay, J.P.; Schauerte, W.; Peichl, L.; Klein, W.; Korte, F.

1985-10-01

190

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 essentially nonvolatile. 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.

J. H. Seinfeld

2007-03-01

191

Highly flexible and tough concentric triaxial polystyrene fibers.  

Science.gov (United States)

A combination of appropriate reinforcing material and morphology led to the highly tough, flexible, and strong polystyrene fibers by electrospinning. Concentric fiber morphology with reinforcing elastomeric thermoplastic polyurethane (TPU) sandwiched between the two layers of polystyrene made by a special nozzle (triaxial) showed toughness of >270 J g(-1) and 300% elongation without any cracks in comparison to toughness of <0.5 J g(-1) and elongation at break of <5% of polystyrene single fibers. The concentric triaxial morphology showed great advantage in comparison to the coaxial structure. Toughness and elongation at break were 1376 and 628% higher, respectively, for triaxial morphology in comparison to the coaxial fibers because of the better interface from the sandwich structure. PMID:24684423

Jiang, Shaohua; Duan, Gaigai; Zussman, Eyal; Greiner, Andreas; Agarwal, Seema

2014-04-23

192

Mitigation of houses with extremely high indoor radon concentrations  

International Nuclear Information System (INIS)

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

2006-05-15

193

Highly fluorescent aggregates modulated by surfactant structure and concentration.  

Science.gov (United States)

The effects of anionic surfactants on the aggregation-induced emission (AIE) feature of cationic M-silole molecules have been studied. The electrostatic binding of M-silole with the surfactants greatly promotes the aggregation of the mixtures. The M-silole/surfactant aggregates at 1:1 charge ratio exhibit the maximum fluorescence intensity. Excess surfactant molecules will distribute the M-silole molecules into different micelles and weaken the fluorescence. The fluorescence intensity of the mixed M-silole/surfactant aggregates can be effectively modulated by choosing different surfactants. The gemini surfactants display a much stronger ability of enhancing fluorescence intensity than do the single-chain surfactants. Especially, the gemini surfactant with benzene rings shows the best performance in enhancing fluorescence of M-silole due to both the strongest aggregation ability and the pi-pi interaction with M-silole. PMID:20572643

Yu, Defeng; Zhang, Qun; Wu, Chunxian; Wang, Yingxiong; Peng, Lihua; Zhang, Deqing; Li, Zhibo; Wang, Yilin

2010-07-15

194

Introduction of high oxygen concentrations into silicon wafers by high-temperature diffusion  

CERN Multimedia

The tolerance of silicon detectors to hadron irradiation can be improved by the introduction of a high concentration of oxygen into the starting material. High-resistivity Floating-Zone (FZ) silicon is required for detectors used in particle physics applications. A significantly high oxygen concentration (>10/sup 17/ atoms cm/sup -3 /) cannot readily be achieved during the FZ silicon refinement. The diffusion of oxygen at elevated temperatures from a SiO/sub 2/ layer grown on both sides of a silicon wafer is a simple and effective technique to achieve high and uniform concentrations of oxygen throughout the bulk of a 300 mu m thick silicon wafer. (7 refs).

Casse, G L; Lemeilleur, F; Ruzin, A; Wegrzecki, M

1999-01-01

195

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, 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

2000-10-01

196

Reactions of energetic carbon-11 with benzene leading to acetylene  

International Nuclear Information System (INIS)

The reactions of energetic carbon-11 leading to acetylene were studied in specifically deuteriated benzene and 50/50 mixtures of perdeuteriated and perprotonated benzenes and alkanes. The contributions of intermolecular and intramolecular mechanisms in acetylene formation in benzene were deduced from the relative yields of the three isotopic acetylenes /sup (11)/C_2H_2, /sup (11)/C_2HD, and /sup (11)/C_2D_2. High-energy stripping and abstraction reactions of /sup (11)/C_2 and /sup (11)/C_2H ions appear to account for acetylene formed via an intermolecular pathway. After correction for the intermolecular mechanisms, the remaining acetylene is formed mainly by direct insertion (? or ?) plus a small contribution from a mechanism involving random selection of H or D in the benzene molecule

1987-06-04

197

Thermal management and overall performance of a high concentration PV  

Science.gov (United States)

An advanced thermal management approach for HCPV systems is demonstrated in this manuscript, proposing the concept of efficient heat recovery at ultra high concentration ratios by collecting the heat on a high temperature level. With the availability of this low grade heat, the efficiency of the HCPV system is increased further as the 'waste' heat is supplied to different thermal consumers engaging in thermal desalination or adsorption cooling processes. To asses the value of the concept, we have estimated the economic value of heat with regard to its consumer and observed that this differs from its thermodynamic value. This valuable input is was used to determine the overall generated value of a dual output system as a function of the operation temperature, where we have actively demonstrated a superior performance of the HCPVT.

Escher, Werner; Paredes, Stephan; Zimmermann, Severin; Ong, Chin Lee; Ruch, Patrick; Michel, Bruno

2012-10-01

198

Shock initiation studies on high concentration hydrogen peroxide  

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-01-01

199

First DIAMEX partitioning using genuine high active concentrate  

Energy Technology Data Exchange (ETDEWEB)

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)

Serrano-Purroy, D.; Christiansen, B.; Malmbeck, R.; Glatz, J.P.; Baron, P.; Madic, C.; Modolo, G

2004-07-01

200

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

International Nuclear Information System (INIS)

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

2004-05-18

 
 
 
 
201

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2004-05-18

202

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 benzene concentration be reduced

1995-08-02

203

Assessing benzene-induced toxicity on wild type Euglena gracilis Z and its mutant strain SMZ.  

Science.gov (United States)

Benzene is a representative member of volatile organic compounds and has been widely used as an industrial solvent. Groundwater contamination of benzene may pose risks to human health and ecosystems. Detection of benzene in the groundwater using chemical analysis is expensive and time consuming. In addition, biological responses to environmental exposures are uninformative using such analysis. Therefore, the aim of this study was to employ a microorganism, Euglena gracilis (E. gracilis) as a putative model to monitor the contamination of benzene in groundwater. To this end, we examined the wild type of E. gracilis Z and its mutant form, SMZ in their growth rate, morphology, chlorophyll content, formation of reactive oxygen species (ROS) and DNA damage in response to benzene exposure. The results showed that benzene inhibited cell growth in a dose response manner up to 48 h of exposure. SMZ showed a greater sensitivity compared to Z in response to benzene exposure. The difference was more evident at lower concentrations of benzene (0.005-5 ?M) where growth inhibition occurred in SMZ but not in Z cells. We found that benzene induced morphological changes, formation of lipofuscin, and decreased chlorophyll content in Z strain in a dose response manner. No significant differences were found between the two strains in ROS formation and DNA damage by benzene at concentrations affecting cell growth. Based on these results, we conclude that E. gracilis cells were sensitive to benzene-induced toxicities for certain endpoints such as cell growth rate, morphological change, depletion of chlorophyll. Therefore, it is a potentially suitable model for monitoring the contamination of benzene and its effects in the groundwater. PMID:24034892

Peng, Cheng; Arthur, Dionne M; Sichani, Homa Teimouri; Xia, Qing; Ng, Jack C

2013-11-01

204

High gain, wide field of view concentrator for optical communications.  

Science.gov (United States)

The field of view and gain of optical concentrators used within free space optical communications systems are constrained by conservation of etendue. In this Letter, consideration of the processes in a fluorescent concentrator leads to a simple design strategy for these concentrators for this application. Significantly, because fluorescent concentrators do not conserve etendue, this can lead to concentrators with wider fields of view and higher gains. A model of a fluorescent concentrator containing a quantum dot material suggests that it could have a gain 50 times higher than an etendue conserving concentrator with the same field of view. PMID:24686597

Collins, Steve; O'Brien, Dominic C; Watt, Andrew

2014-04-01

205

Thermal denitration of high concentration nitrate salts waste water  

International Nuclear Information System (INIS)

This study investigated the thermodynamic and the thermal decomposition properties of high concentration nitrate salts waste water for the lagoon sludge treatment. The thermodynamic property was carried out by COACH and GEMINI II based on the composition of nitrate salts waste water. The thermal decomposition property was carried out by TG-DTA and XRD. Ammonium nitrate and sodium nitrate were decomposed at 250 .deg. C and 730 . deg. C, respectively. Sodium nitrate could be decomposed at 450 .deg. C in the case of adding alumina for converting unstable Na2O into stable Na2O.Al2O3. The flow sheet for nitrate salts waste water treatment was proposed based on the these properties data. These will be used by the basic data of the process simulation

2003-11-27

206

High concentration of gadolinium ion modifying isolated rice mitochondrial biogenesis.  

Science.gov (United States)

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

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

2013-12-01

207

Verification of Fresnel lens in high concentration photovoltaic system  

Science.gov (United States)

An approach using micro lens arrays to confine the cone angle of light source in a solar simulator has been proposed to verify the Fresnel lens in a high concentration photovoltaic (HCPV) system. Compared with other three prior arts by the computer simulation, the proposed method had the characteristics of the better approximation to the direct normal insolation and the low cost. Also, to ensure the erection of the evaluation system, the tolerance of lens alignment has been analyzed. The results showed that to maintain at least the 50% of the maximum luminous flux incident on the solar cell, the transverse and longitudinal tolerances of ±1.4 mm and ±4 mm, respectively, were required.

Wei, An-Chi; Sze, Jyh-Rou; Chern, Jyh-Long

2012-10-01

208

Hydrothermally enhanced electrochemical oxidation of high concentration refractory perfluorooctanoic acid.  

Science.gov (United States)

A green hydrothermally enhanced electrochemical oxidation (HTEO) technique is developed to treat the high concentration refractory perfluorooctanoic acid (PFOA) wastewater on boron-doped diamond (BDD) film electrode. Results show that HTEO can demonstrate higher degradation efficiency for PFOA than the normal electrochemical oxidation (EO) process, with the removal of PFOA, total organic carbon (TOC), and organic fluorine in the HTEO process increasing by 1.1, 1.8, and 2.1 times, respectively. The kinetics study indicates that the degradation of PFOA follows a first-order reaction in the HTEO process with the apparent reaction rate constant 3.1 times higher than that in the EO process. The higher degradation efficiency of PFOA is due to the hydrothermal enhancement in electrochemical properties of the electrode and solution. Compared with EO, during the HTEO process, the conductivity and ionic migration rate of the solution is improved by 540% and 60%, respectively. In addition, the Tafel slope is increased to 343 from 279 mV dec(-1), indicating an inhibition effect of oxygen evolution reaction and a more effective oxidation of PFOA. In particular, the hydrothermal condition promotes a high formation rate of hydroxyl radical with the concentration almost 2 times of that in EO, which is considered the inner factor leading to the higher degradation efficiency. The density functional theory simulations demonstrate that the nonterminal C-C bonds in the main carbon chain can be easily destructed in the hydrothermal condition, as confirmed by the experimental detection of intermediates of C(5)F(11)COOH, C(4)F(9)COOH, C(3)F(7)COOH, C(2)F(5)COOH, CF(3)COOH, and some dicarboxylic acids. As a result, a reaction pathway is tentatively proposed. PMID:22013988

Xiao, Hanshuang; Lv, Baoying; Zhao, Guohua; Wang, Yujing; Li, Mingfang; Li, Dongming

2011-12-01

209

Positronium inhibition by chlorine substituted benzenes in benzene  

International Nuclear Information System (INIS)

Positron lifetime measurements have been performed on CCl4 and 12 different chlorobenzenes in benzene solutions. The solutes cause inhibition of Ps-formation but no quenching. The strongest inhibition effect was caused by CCl4. Among the chlorobenzenes it was found that the isomeric forms of trichlorobenzenes were the most effective inhibitors and hexachlorobenzene had the smallest effect of inhibition. (Auth.)

1976-10-15

210

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

211

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

International Nuclear Information System (INIS)

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

2011-02-01

212

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

213

High-performance deployable structures for the support of high-concentration ratio solar array modules  

Science.gov (United States)

A study conducted on high-performance deployable structures for the support of high-concentration ratio solar array modules is discussed. Serious consideration is being given to the use of high-concentration ratio solar array modules or applications such as space stations. These concentrator solar array designs offer the potential of reduced cost, reduced electrical complexity, higher power per unit area, and improved survivability. Arrays of concentrators, such as the miniaturized Cassegrainian concentrator modules, present a serious challenge to the structural design because their mass per unit area (5.7 kg/square meters) is higher than that of flexible solar array blankets, and the requirement for accurate orientation towards the Sun (plus or minus 0.5 degree) requires structures with improved accuracy potentials. In addition, use on a space station requires relatively high structural natural frequencies to avoid deleterious interactions with control systems and other large structural components. The objective here is to identify and evaluate conceptual designs of structures suitable for deploying and accurately supporting high-concentration ratio solar array modules.

Mobrem, M.

1985-10-01

214

On the Diffusion of High Concentrations by Shaking  

Science.gov (United States)

This work investigates the role that surface wave action can play in the diffusion of solutes in clear water. The transport of dissolved pollutants (e.g., industrial salts) is an important environmental issue where fluid dynamics can help devise mitigation measures. Unlike in pollution containment problems, many industrial applications exist in which an enhancement of mass transport, or dispersion, is rather sought. For the purposes of this study, a rigid container is filled with two fluids, one of which comprises a high concentration of a solute. Solutions of the Navier- Stokes and mass transfer equations are obtained by a new surface marker and micro cell method. Lagrangian surface markers are used to track the free surface. Strong sloshing is imparted on the fluids by shaking the solid tank at its wave natural frequency. This results in significant free surface deformations whose amplitudes are indicative of the existence of high fluid velocities which can cause measurable advection of the solute contaminants. As expected, mass diffusion is enhanced by the shaking process, but, depending on the relative position of the clear and contaminated bodies, the enhancement may be localized in the upper fluid layers.

Raad, Peter; Fadda, Dani; Bidoae, Razvan

1996-11-01

215

High urinary phthalate concentration associated with delayed pubarche in girls.  

Science.gov (United States)

Phthalates are a group of chemicals present in numerous consumer products. They have anti-androgenic properties in experimental studies and are suspected to be involved in human male reproductive health problems. A few studies have shown associations between phthalate exposure and changes in pubertal timing among girls, although controversies exist. We determined the concentration of 12 phthalate metabolites in first morning urine samples from 725 healthy Danish girls (aged 5.6-19.1 years) in relation to age, pubertal development (breast and pubic hair stage) and reproductive hormone levels (luteinizing hormone, oestradiol and testosterone). Furthermore, urinary phthalates were determined in 25 girls with precocious puberty (PP). In general, the youngest girls with less advanced pubertal development had the highest first morning urinary concentration of the monobutyl phthalate isoforms (?MBP((i+n))), monobenzyl phthalate (MBzP), metabolites of di-(2-ethylhexyl) phthalate (?DEHPm) and of di-iso-nonyl phthalate (?DINPm). After stratification of the urinary phthalate excretion into quartiles, we found that the age at pubarche was increasing with increasing phthalate metabolite quartiles (except for MEP). This trend was statistically significant when all phthalate metabolites (except MEP) were summarized and expressed as quartiles. No association between phthalates and breast development was observed. In addition, there were no differences in urinary phthalate metabolite levels between girls with PP and controls. We demonstrated that delayed pubarche, but not thelarche, was associated with high phthalate excretion in urine samples from 725 healthy school girls, which may suggest anti-androgenic actions of phthalates in our study group of girls. PMID:22428786

Frederiksen, H; Sørensen, K; Mouritsen, A; Aksglaede, L; Hagen, C P; Petersen, J H; Skakkebaek, N E; Andersson, A-M; Juul, A

2012-06-01

216

High urinary phthalate concentration associated with delayed pubarche in girls  

DEFF Research Database (Denmark)

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

Frederiksen, H; Sørensen, K

2012-01-01

217

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

218

090320 benzene supplementary note final  

…stems and leaves (Collins et al., 2002). Upon entering the leaves, benzene may be lost through transpiration (Burken and Schnoor, 1998) or metabolised. Any resulting metabolites can either be transpired, or retained in the leaves as bound residues (Collins et al., 2002), or incorporated into cell structures…

219

090320 benzene supplementary note final  

…means that roots are an important organ for metabolism of organic compounds (Collins et al., 2002). Resulting metabolites may be retained in the roots or transported around the plant. These metabolites may be more or less toxic to humans than the original organic chemical. As benzene is only moderately…

220

Occupational exposure to benzene at the ExxonMobil refinery at Baton Rouge, Louisiana (1977-2005).  

Science.gov (United States)

Because crude oil contains up to 3% benzene and there is an association between high chronic exposure to appreciable concentrations of benzene and acute myelogenous leukemia, exposure of refinery workers has been studied for many years. To date, no extensive industrial hygiene exposure analyses for historical benzene exposure have been performed, and none have focused on the airborne concentrations in the workplace at specific refineries or for specific tasks. In this study, the authors evaluated the airborne concentrations of benzene and their variability over time at the ExxonMobil refinery in Baton Rouge between 1977 and 2005. Refinery workers were categorized into 117 worker groups using company job descriptions. These 117 groups were further collapsed into 25 job categories based on similarity of measured exposure results. Results of 5289 personal air samples are included in this analysis; 3403 were considered nontask (>or= 180 min) personal samples, and 830 were considered task-related (< 180 min) personal samples; the remainder did not fit in either category. In general, nontask personal air samples indicated that exposures of the past 30 years were generally below the occupational exposure limit of 1 ppm, but there was only a small, decreasing temporal trend in the concentrations. The job sampled most frequently during routine operations was process technician and, as broken down by area, resulted in the following mean benzene concentrations: analyzers (mean = 0.12 ppm), coker (mean = 0.013 ppm), hydrofiner (mean = 0.0054 ppm), lube blending and storage (mean = 0.010 ppm), waste treatment (mean = 0.092 ppm), and all other areas (mean = 0.055 ppm). Task-based samples indicated that the highest exposures resulted from the sampling tasks, specifically from those performed on process materials; in general, though, even these tasks had concentrations well below the STEL of 5 ppm. The most frequently sampled task was gauging (mean = 0.12 ppm). Task-related exposures were also similar across job categories for a given task, with a few exceptions. This study thus provides a task-focused analysis for occupational exposure to benzene during refinery operations, which can be insightful for understanding exposures at this refinery and perhaps others operated since about 1975. PMID:19544135

Panko, Julie M; Gaffney, Shannon H; Burns, Amanda M; Unice, Ken M; Kreider, Marisa L; Booher, Lindsay E; Gelatt, Richard H; Marshall, J Ralph; Paustenbach, Dennis J

2009-09-01

 
 
 
 
221

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

Science.gov (United States)

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

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

2013-12-01

222

Intercomparison of High-Volume PM10 Samplers at a Site with High Particulate Concentrations.  

Science.gov (United States)

Commercially available high-volume PM10 samplers were intercompared at a site in Phoenix characterized by high concentrations of coarse particles. Over a 21-day period, SierraAndersen 321A (SA 321A) samplers gave PM10 measurements 58% higher than the Wedd...

L. J. Purdue C. E. Rodes K. A. Rehme D. M. Holland A. E. Bond

1986-01-01

223

Benzene in blood as a biomarker of low level occupational exposure  

Energy Technology Data Exchange (ETDEWEB)

The occupational airborne exposure to benzene of 150 workers employed in petrol stations and a refinery plant was assessed using personal sampling pumps. All workers provided blood samples after the end of work and on the following morning before resuming work. Benzene concentrations in the blood of 243 non-occupationally-exposed subjects were also measured. The median occupational benzene exposure for all 150 workers studied was 80 {mu}g/m{sup 3}. Overall median blood benzene of all workers was 251 ng/l at the end of the shift, and 174 ng/l the following morning. The benzene concentrations measured in blood collected the following morning proved to be significantly lower than those measured at the end of the shift. Median blood benzene for the 243 'normal' subjects was 128 ng/l, which was significantly lower than that measured in the workers before a new work shift. The median blood benzene concentration was significantly higher in smokers than in non-smokers, both in the general population (210 ng/l vs. 110 ng/l) and in the exposed workers at the end of the shift (476 ng/l vs. 132 ng/l) and the following morning (360 ng/l vs. 99 ng/l). End-of-shift blood benzene correlated significantly with environmental exposure; this correlation was better in the 83 non-smokers than in the 67 smokers. In non-smokers with the median benzene occupational exposure of 50 {mu}g/m{sup 3}, no difference was found in blood benzene concentration in exposed and non-exposed subjects.

Brugnone, F.; Perbellini, L.; Romeo, L.; Cerpelloni, M.; Bianchin, M.; Tonello, A. [Institute of Occupational Medicine, University of Verona, Policlinico Borgo Roma, 37134 Verona (Italy)

1999-09-01

224

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

225

1,2'-Bis(4-aminophenoxy)benzene based designed fluoro-poly(ether-imide)/MMT clay nanocomposites: Synthesis and properties for high performance applications  

Energy Technology Data Exchange (ETDEWEB)

In an effort to develop structure-property understanding of fluoro-polymer/inorganic clay nanocomposite (i.e., Ceramer) technology, two series of fluoro-poly(ether amic acid) (6F-PEAA)/organosoluble Montmorillonite (MMT) clay nanocomposite formulations containing varying percentage of diamine modified (ion-exchanged) organosoluble-MMT clay were prepared from the partially fluorinated fluoro poly(ether-amic acid)s (6F-PEAA) synthesized by reacting on 2,2'-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and di-ether-containing diamines, such as 1,2'-bis(4-aminophenoxy) benzene (o-BAPOB) and 4,4'-bis(4-aminophenoxy) diphenyl sulfone (p-SED), respectively. Self supporting films were cast from these formulations and cured at elevated temperatures. XRD data, indirectly confirmed the exfoliation of organosoluble-MMT clay at molecular level in the nanocomposite. The solubility, chemical resistance, morphology, thermo-oxidative stability, thermal degradation kinetics, mechanical behavior, and moisture absorption of these [(6F-PEI)/MMT clay] nanocomposite films were systematically studied.

Vora, Rohitkumar H. [Advanced Polymer Research and Technologies, 505 Cinder Road, Edison, NJ 08820 (United States)]. E-mail: rohitvora@apr-technologies.com; Vora, Mayur [Organo Chemicals Industries, 11/89, Sawan Bhavan, Naigaon Cross Road, Dadar (East), Bombay 400022 (India)

2006-07-25

226

1,2'-Bis(4-aminophenoxy)benzene based designed fluoro-poly(ether-imide)/MMT clay nanocomposites: Synthesis and properties for high performance applications  

International Nuclear Information System (INIS)

In an effort to develop structure-property understanding of fluoro-polymer/inorganic clay nanocomposite (i.e., Ceramer) technology, two series of fluoro-poly(ether amic acid) (6F-PEAA)/organosoluble Montmorillonite (MMT) clay nanocomposite formulations containing varying percentage of diamine modified (ion-exchanged) organosoluble-MMT clay were prepared from the partially fluorinated fluoro poly(ether-amic acid)s (6F-PEAA) synthesized by reacting on 2,2'-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and di-ether-containing diamines, such as 1,2'-bis(4-aminophenoxy) benzene (o-BAPOB) and 4,4'-bis(4-aminophenoxy) diphenyl sulfone (p-SED), respectively. Self supporting films were cast from these formulations and cured at elevated temperatures. XRD data, indirectly confirmed the exfoliation of organosoluble-MMT clay at molecular level in the nanocomposite. The solubility, chemical resistance, morphology, thermo-oxidative stability, thermal degradation kinetics, mechanical behavior, and moisture absorption of these [(6F-PEI)/MMT clay] nanocomposite films were systematically studied

2006-07-25

227

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

228

Thermal decomposition of propargyl bromide and the subsequent formation of benzene  

Energy Technology Data Exchange (ETDEWEB)

Mixtures of 3% C[sub 3]H[sub 3]Br[sub 3], 3% CHBr = 5% H[sub 2], and 3% CHBr + 5% D[sub 2], all three containing neon diluent, were analyzed behind reflected shock waves by time-of-flight mass spectrometry to investigate the role of propargyl radical as precursor to benzene formation at high temperatures. The first mixture yields significant concentrations of benzene over the range 1,310--1,470 K; benzene yield is observed to increase twofold in the second mixture at comparable temperatures. The third mixture reveals a temporal ratio of HBr/(DBr + Br) [approximately] 1, which is interpreted as evidence of an equal contribution from each of the two initiation reactions: (1) CHBr [yields] c-C[sub 3]H[sub 2] + HBr, where c-C[sub 3]H[sub 2] is singlet cyclopropenylidene; and (2) CHBr [yields] C[sub 3]H[sub 3] + Br. In the first two mixtures, the major products are acetylene, butadiyne, C[sub 6]H[sub 2], benzene and HBr. A 2% propyne + neon mixture was also studied over the temperature range 1,750--2,620 K. The reaction profiles for propyne, acetylene, butadiyne, and benzene are modeled satisfactorily with a mechanism in which the dominant channel for propyne dissociation produces c-C[sub 3]H[sub 2] + H[sub 2]. Reaction pathways involving c-C[sub 3]H[sub 2] insertion into C-H bonds are presented along with an analysis for the important disproportionation step, c-C[sub 3]H[sub 2] + propyne [yields] 2C[sub 3]H[sub 3]. Inclusion of six steps describing the reactions of bromine containing species to the core propyne decomposition mechanism results in satisfactory fits to the CHBr and CHBr + H[sub 2] experiments. It is concluded that benzene production in these mixtures is best explained by a sequence of reactions initiated by the dimerization of propargyl radicals.

Kern, R.D.; Chen, H. (University of New Orleans, LA (United States). Dept. of Chemistry); Kiefer, J.H.; Mudipalli, P.S. (University of Illinois, Chicago (United States). Dept. of Chemical Engineering)

1995-01-01

229

Laser photochemical synthesis of benzene and its derivatives. [Substituted benzenes  

Energy Technology Data Exchange (ETDEWEB)

A cw CO/sub 2/ tunable laser is employed to irradiate an allyl halide selected from allyl chloride, allyl bromide, allyl fluoride, 2-methyl-3-chloropropene, and 2,3-dichloropropene and contained in one or more reaction cells at a predetermined pressure. A predetermined power level from about 25 to 150 watts, an irradiating time from about 0.2 second to about 60 seconds, and a selected radiation line for example P(36), P(32), P(26), or P(22) (that is resonant with an absorption band of the selected allyl halide) are employed to achieve dissociation of the selected allyl halide and to achieve a laser-induced photochemical synthesis of benzene and substituted benzenes.

McDonald, J.K.; Merritt, J.A.

1983-12-27

230

Oxidation of benzene with hydrogen peroxide catalyzed with ferrocene in the presence of pyrazine carboxylic acid  

Science.gov (United States)

It is found that ferrocene in the presence of small amounts of pyrazine carboxylic acid (PCA) effectively catalyzes the oxidation of benzene to phenol with hydrogen peroxide. Two main differences upon the oxidation of two different substrates, i.e., cyclohexane and benzene, with the same H2O2-ferrocene-PCA catalytic system are revealed: the rates of benzene oxidation and hydrogen peroxide decomposition are several times lower than the rate of cyclohexane oxidation at close concentrations of both substrates, and the rate constant ratios for the reactions of oxidizing particles with benzene and acetonitrile are significantly lower than would be expected for reactions involving free hydroxyl radicals. The overall rate of hydrogen peroxide decomposition, including both the catalase and oxidase routes, is lower in the presence of benzene than in the presence of cyclohexane. It is suggested on the grounds of these data that a catalytically active particle different from the one generated in the absence of benzene is formed in the presence of benzene. This particle catalyzes hydrogen peroxide decomposition less efficiently than the initial complex and generates a dissimilar oxidizing particle that exhibits higher selectivity. It is shown that reactivity of the system at higher concentrations of benzene differs from that of an initial system not containing an aromatic component with the capability of ?-coordination with metal ions.

Shul'pina, L. S.; Durova, E. L.; Kozlov, Yu. N.; Kudinov, A. R.; Strelkova, T. V.; Shul'pin, G. B.

2013-12-01

231

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

Energy Technology Data Exchange (ETDEWEB)

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{sub 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{sub x}. The decreasing trends of NO{sub 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. (Author)

Palmgren, F.; Hansen, A.B.; Berkowicz, R.; Skov, H. [National Environmental Research Inst., Roskilde (Denmark)

2001-01-01

232

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)

2001-01-01

233

Reduction of PAH and soot precursors in benzene flames by addition of ethanol.  

Science.gov (United States)

A one-dimensional premixed flame model (PREMIX) and schemes resulting from the merging of validated kinetic schemes for the oxidation of the components of the present mixtures (benzene and ethanol) were used to investigate the effect of oxygenated additives on aromatic species, which are known to be soot precursors, in fuel-rich benzene combustion. The specific flames were low-pressure (45 mbar), laminar, premixed flames at an equivalence ratio of 2.0. The blended fuels were formed by incrementally adding 4% wt of oxygen (ethanol) to the neat benzene flame and by keeping the inert mole fraction (argon) and the equivalence ratio constants. Special emphasis was directed toward the causes for the concentration-dependent influence of the blends on the amount of polycyclic aromatic hydrocarbons (PAHs) formed. The effects of oxygenate addition to the benzene base flame were seen to result in interesting differences, especially regarding trends to form PAH. The modeling results indicated that the concentration of acetylene and propargyl radicals, the main PAH precursors, as well as the PAH amounts were lower in the flame of the ethanol-benzene fuel mixture than in the pure benzene flame and that all of the formed PAHs were issued from the phenyl radical. Finally, the modeling results provided evidence that the PAH reduction was a result of simply replacing "sooting" benzene with "nonsooting" ethanol without influencing the combustion chemistry of the benzene. PMID:22429107

Golea, Djemaa; Rezgui, Yacine; Guemini, Miloud; Hamdane, Soumia

2012-04-12

234

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

235

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

236

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

237

Efficacy of high iodine concentration contrast medium with saline pushing in hepatic CT in patients with chronic liver disease. Comparison of high doses-standard contrast medium concentration  

International Nuclear Information System (INIS)

The aim of this study was to compare the enhancement of liver parenchyama with high iodine concentration contrast medium with saline pushing to that with high doses standard iodine concentration in hepatic CT in patients with chronic liver disease. There was no statistically significant difference regarding to the enhancement of liver parenchyama between the 370 mgI/ml of contrast medium with saline pushing and high doses standard iodine concentration contrast medium. (author)

2006-12-01

238

Slow Neutron Scattering by Benzene  

International Nuclear Information System (INIS)

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

1963-01-01

239

A Comparative Study Of Efficacy Of Gamma Benzene Hexachloride Lotion And Benzyl Benzoate Emulsion  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In a clinical study, the efficacy of gamma benzene hexachloride lotion was evaluated in 50 adult patients in scabies using 2% concentration and in 24 children under 8 years of age using 1% concentration. Use of other scabicidal preparation was 25% benzyl benzoate emulsion for a comparison with second group of patients of the same size. Two applications for 1 day of 2% gamma benzene hexachloride lotion proved to be far more effective a scabicidal drug (68% cu...

1995-01-01

240

Benzene exposure in the shoemaking industry in China, a literature survey, 1978-2004.  

Science.gov (United States)

This article presents a summary of benzene exposure levels in the shoemaking industry in China reported in the Chinese medical literature between 1978 and 2004. A comprehensive search identified 182 papers reporting such exposure data. These papers could be classified into two categories: benzene poisoning case reports and industrial hygiene surveys. From each paper, the following information was abstracted whenever available: location and year of occurrence, occupation and/or task involved, benzene content in adhesives/solvents, work environment, working conditions, working hours, diagnosis, and air monitoring data of benzene. A total of 333 benzene measurements (88 averages, 116 minimums, 129 maximums) in the shoemaking industry were reported in the 182 papers identified. The data were analyzed in terms of geographical location, time period, type of ownership (state, township, or foreign), type of report (benzene poisoning reports vs. industrial hygiene surveys), and job title (work activity) or process. The reported data covered a wide range; some measurements were in excess of 4500 mg/m(3). Thirty-five percent of the reported benzene concentrations were below 40 mg/m(3), which was the national occupational exposure limit (OEL) for benzene between 1979 and 2001. The remaining 65% measurements, which exceeded the national OEL in effect at the time, and were distributed as follows: 40-100 mg/m(3), 11%; 100-300 mg/m(3), 21%; 300-500 mg/m(3), 13%; and 500+ mg/m(3), 20%. However, only 24% of the reported measurements after 2002 were below 6 mg/m(3), i.e., Permissible Concentration-Time Weighted Average (PC-TWA) and 10 mg/m(3), i.e., Permissible Concentration-Short Term Exposure Limit (PC-STEL), the newly amended benzene OELs in effect after May 2002. The data demonstrated that the majority of the facilities in the shoemaking industry reported in the literature were not in compliance of the OEL for benzene in effect at the time. Overall, the data show a clear downward trend of benzene exposure levels over the years, particularly after the introduction of the new lower OEL in 2002. Even though substantially lower when compared to levels in the past, current benzene exposure measurements from the literature review suggest that many facilities in the shoemaking industry in China have benzene concentrations that are still above the new OEL. The reported data, stratified by job, year and survey reason, can be used as part of the information and analysis for developing a job-exposure matrix in retrospective exposure assessment and thus may be part of the information used in developing historical exposure estimates in epidemiologic studies of shoe workers. PMID:16989927

Wang, Laiming; Zhou, Yimei; Liang, Youxin; Wong, Otto; Armstrong, Thomas; Schnatter, A Robert; Wu, Qiangen; Fang, Jinbin; Ye, Xibiao; Fu, Hua; Irons, Richard D

2006-11-01

 
 
 
 
241

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.)

1996-01-01

242

Inhibition of human topoisomerase II in vitro by bioactive benzene metabolites  

Energy Technology Data Exchange (ETDEWEB)

Benzene is a clastogenic and carcinogenic agent that induces acute myelogenous leukemia in humans and multiple types of tumors in animals. Previous research has indicated that benzene must first be metabolized to one or more bioactive species to exert its myelotoxic and genotoxic effects. To better understand the possible role of individual benzene metabolites in the leukemogenic process, as well as to further investigate inhibition of topoisomerase 11 by benzene metabolites, a series of known and putative benzene metabolites, phenol, 4{prime}4-biphenol, 2,2{prime}-biphenol, hydroquinone, catechol, 1,2,4-benzenetriol, 1,4-benzoquinone, and trans-trans-muconaldehyde were tested for inhibitory effects in vitro on the human topoisomerase 11 enzyme. With minor modifications of the standard assay conditions, 1,4-benzoquinone and trans-trans-muconaldehyde were shown to be directly inhibitory, whereas all of the phenolic metabolites were shown to inhibit enzymatic activity following bioactivation using a peroxidase activation system. The majority of compounds tested inhibited topoisomerase 11 at concentrations at or below 10 pM. These results confirm and expand upon previous findings from our laboratory and indicate that many of the metabolites of benzene could potentially interfere with topoisomerase 11. Since other inhibitors of topoisomerase 11 have been shown to induce leukemia in humans, inhibition of this enzyme by benzene metabolites may also play a role in the carcinogenic effects of benzene. 48 refs., 4 tabs.

Frantz, C.E.; Chen, Hongwei; Eastmond, D.A. [Univ. of California, Riverside, CA (United States)

1996-12-01

243

Biodegradation of benzene and a BTX mixture using immobilized activated sludge  

Energy Technology Data Exchange (ETDEWEB)

Aerobic biodegradation of benzene was studied using activated sludge immobilized in calcium alginate (immobilization by entrapment), and also attached to a silica based catalyst support (immobilization by attachment). Hydrogen peroxide was used as a source of dissolved oxygen to eliminate physical removal of benzene due to aeration. Abiotic losses of benzene were accounted for. A recirculation reactor, run in both batch and continuous feed mode, was used to determine the kinetic parameters. The system response was examined by following changes in benzene concentration, flow rate, and biomass loading. The system was modeled mathematically and the kinetic parameters were determined. Biological removal of a mixture of benzene, toluene and o, m and p-xylene (BTX) was also studied. In a typical batch experiment starting with 100 ppm benzene, the substrate utilization rate (k{sub M}), when expressed per unit weight of dry catalyst, had a value of 0.4453 ppm/h/g dry beads for the alginate system, and 0.067 ppm/h/g dry beads for the celite catalyst carrier. Activated sludge was characterized for biodegradation of benzene. Isolations were done for unacclimated, acclimated and end run samples. About 67% of the isolates could be assigned to a genus. These were Bacillus, Microbacterium, Plesiomonas, Kurthia, Klebsiella, Lactobacillus, and Pseudomonas. From among the fifteen isolates found in the end run group, an isolate identified as Pseudomonas was established as a primary degrader of benzene.

Lodaya, M.P.

1989-01-01

244

Airborne benzene exposures from cleaning metal surfaces with small volumes of petroleum solvents.  

Science.gov (United States)

Airborne benzene concentrations were measured in a room with controlled air exchange during surface cleaning with two petroleum-based solvents (a paint thinner and an engine degreaser). The solvents were spiked with benzene to obtain target concentrations of 0.001, 0.01, and 0.1% by volume in the liquid. Personal samples on the worker and area samples up to 1.8m away were collected over 12 events (n=84 samples) designed to examine variation in exposure with solvent type, cleaning method (rag wipe or spatula scrape), surface area cleaned, air exchange rate, solvent volume applied, and distance from the cleaned surface. Average task breathing zone concentrations of benzene represented by 18-32 min time-weighted averages were 0.01 ppm, 0.05 ppm, and 0.27 ppm, when the solvents contained approximately 0.003, 0.008, and 0.07% benzene. Solvent benzene concentration, volume applied, and distance from the handling activities had the greatest effect on airborne concentrations. The studied solvent products containing 0.07% benzene (spiked) did not exceed the current OSHA permissible exposure limit of 1 ppm (averaged over 8h) or the ACGIH Threshold Limit Value of 0.5 ppm, in any of the tested short-term exposure scenarios. These data suggest that, under these solvent use scenarios, petroleum-based solvent products produced in the United States after 1978 likely did not produce airborne benzene concentrations above those measured if the concentration was less than 0.1% benzene. PMID:23088855

Hollins, Dana M; Kerger, Brent D; Unice, Kenneth M; Knutsen, Jeffrey S; Madl, Amy K; Sahmel, Jennifer E; Paustenbach, Dennis J

2013-06-01

245

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

International Nuclear Information System (INIS)

It was determined Benzene, Toluene and Xylene (BTX) levels in air from paint manufacture assigned to Instituto Colombiano de Seguro Social with the purpose to evaluate the occupational hazard caused by the use of these solvents. These results were compared with the threshold limit value (TLV). It was selected as sampling strategy, the methodology of partial period with consecutive samples and charcoal tubes as adsorbent of solvents. The extraction was realized with carbon disulfide and it was used gas chromatography with FID as analysis method. It was found that the method is highly selective because in presence of the others ten solvents, utilized in paint manufacture, were obtained a good separation for BTX. The precision, expressed a variance coefficient, was lower than 10%, the accuracy varied between 85 and 99 % for the three solvents. The airborne concentration found was between no detectable and 55,1 mg/m3 for benzene, 18,3 and 253 mg/m3 for toluene and 11,8 and 122,2 mg/m3 for xylene. The corrected TLV values for benzene, toluene and xylenes according to the brief and scale model for the ten hours shift were 1,1, 132 and 304 mg/m3 respectively. It was found occupational risk for benzene in some workplaces; this one is worried because benzene is not used as raw material for the paint manufacture. It was determinate that exist occupational risk in almost every workplace of the industry when it is considered the mixture of the three solvents

2002-01-01

246

Microalgae Tolerance to High Concentrations of Carbon Dioxide: A Review  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ca...

Salih, Fadhil M.

2011-01-01

247

High urinary phthalate concentration associated with delayed pubarche in girls  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Phthalates are a group of chemicals present in numerous consumer products. They have anti-androgenic properties in experimental studies and are suspected to be involved in human male reproductive health problems. A few studies have shown associations between phthalate exposure and changes in pubertal timing among girls, although controversies exist. We determined the concentration of 12 phthalate metabolites in first morning urine samples from 725 healthy Danish girls (aged 5.619.1 years) in ...

2012-01-01

248

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

249

Dome-shaped Fresnel-Köhler: a novel high performance optical concentrator  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The dome-shaped Fresnel-Köhler concentrator is a novel optical design for photovoltaic applications. It is based on two previous successful CPV optical designs: the FK concentrator with a flat Fresnel lens and the dome-shaped Fresnel lens system developed by Daido Steel, resulting on a superior concentrator. This optical concentrator will be able to achieve large concentration factors, high tolerance (i.e. acceptance angle) and high optical efficiency, three key issues when dealing with phot...

Zamora Herranz, Pablo; Benitez Gimenez, Pablo; Li, Yang; Min?ano Dominguez, Juan Carlos; Mendes Lopes, Joao; Araki, Kenji

2012-01-01

250

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

Directory of Open Access Journals (Sweden)

Full Text Available 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.

J. H. Seinfeld

2007-07-01

251

The substituent effect on benzene dications.  

Science.gov (United States)

It was recently postulated that the benzene ring and its 4n + 2 ?-electron analogues are resistant to the substituent effect due to the fact that such systems tend to retain their delocalized character. Therefore, the 4n ?-electron dicationic form of benzene should appear to be less resistant to the substituent effect, as compared with its parent neutral molecule. For this reason the effect of substitution on the dicationic form of benzene was thoroughly investigated and the consequences of single and double substitution (of para- and meta-type) were assessed by means of several parameters, including various aromaticity indices and the Substituent Effect Stabilization Energy (SESE) parameter. It is shown that, distinct from neutral benzene, its dicationic form is much more sensitive to the substitution. However, the dicationic benzene itself, as a moiety with a significant deficit of electrons, will be considered as a strongly electron-withdrawing centre, thus interacting in a cooperative way with electron-donating substituents and in an anticooperative way with electron-withdrawing substituents. Clear differences between singlet- and triplet-state dicationic forms of benzene were also found. Triplet state structures seem to be significantly more delocalized, and as a consequence less sensitive to the substituent effect than the singlet state structures. Finally, the para- and meta-type substitution was investigated and it was found that the disubstituted dicationic benzene exhibits significantly different behaviour from that of neutral benzene. Although the difference between para- and meta-substitution can be found for dicationic benzene, the mechanism responsible for such an observation is different from that present in neutral benzene. Finally, it is shown how and why double ionization of benzene reduces its aromatic character in the singlet dication whereas aromaticity is essentially conserved in the triplet dication. The above findings highlight that in the case of charged analogues of benzene the aromaticity indices can be misleading and are to be used with great precaution. PMID:24469543

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

2014-03-14

252

The design and development of a high concentration and high efficiency photovoltaic concentrator utilizing a curved Fresnel lens  

Energy Technology Data Exchange (ETDEWEB)

The design and development of an innovative photovoltaic concentrator which utilizes a low cost molded Fresnel lens is described. The lens design and fabrication are discussed, as well as the design of the collector module and tracking structure. A description of instrumentation developed to aid in the testing of lenses and solar cells is presented, and includes the test results.

Moffat, A.L.; Scharlack, R.S.

1982-09-01

253

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

254

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 104–105 molecules per cubic centimeter. Here, we present direct measurements of significant amounts of OH radicals of up to 1.8?106 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.

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

2013-01-01

255

Catalytically-mediated denitration of highly HNO3 concentrated solutions  

International Nuclear Information System (INIS)

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

2000-10-24

256

Cerebrospinal fluid concentrations of hypoxanthine, xanthine, uridine and inosine: high concentrations of the ATP metabolite, hypoxanthine, after hypoxia.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

CSF obtained for clinical purposes from newborn, children and adults has been analysed by high pressure liquid chromatography for hypoxanthine, xanthine, inosine, uridine and urate. Large rises in hypoxanthine and to a lesser extent xanthine occur for about 24 h after hypoxia. High concentrations were associated with later evidence of brain damage or subsequent death. Changes in CSF could be independent of those in plasma. Small or negligible rises were associated with localised and generalis...

Harkness, R. A.; Lund, R. J.

1983-01-01

257

Insulinotropic effect of high potassium concentration beyond plasma membrane depolarization.  

Science.gov (United States)

The question whether K(+) depolarization is an appropriate experimental substitute for the physiological nutrient-induced depolarization of the ?-cell plasma membrane was investigated using primary mouse ?-cells and islets. At basal glucose 40 mM K(+) induced a massive monophasic response, whereas 15 mM K(+) had only a minimal insulinotropic effect, even though the increase in the cytosolic Ca(2+) concentration ([Ca(2+)]i) was not inferior to that by 20 mM glucose. In voltage-clamp experiments, Ca(2+) influx appeared as nifedipine-inhibitable inward action currents in the presence of sulfonylurea plus TEA to block compensatory outward K(+) currents. Under these conditions, 15 mM K(+) induced prolonged action currents and 40 mM K(+) transformed the action current pattern into a continuous inward current. Correspondingly, 15 mM K(+) led to an oscillatory increase and 40 mM K(+) to a plateau of [Ca(2+)]i superimposed on the [Ca(2+)]i elevated by sulfonylurea plus TEA. Raising K(+) to 15 or 40 mM in the presence of sulfonylurea (±TEA) led to a fast further increase of insulin secretion. This was reduced to basal levels by nifedipine or CoCl2. The effects of 15 mM K(+) on depolarization, action currents, and insulin secretion were mimicked by adding 35 mM Cs(+) and those of 40 mM K(+) by adding 35 mM Rb(+), in parallel with their ability to substitute for K(+) as permeant cation. In conclusion, the alkali metals K(+), Rb(+), or Cs(+) concentration-dependently transform the pattern of Ca(2+) influx into the ?-cell and may thus generate stimuli of supraphysiological strength for insulin secretion. PMID:24452455

Belz, M; Willenborg, M; Görgler, N; Hamada, A; Schumacher, K; Rustenbeck, I

2014-03-01

258

Preparation of high concentration polyaluminum chloride with high content of Alb or Alc.  

Science.gov (United States)

A novel membrane distillation concentration method was used to prepare high concentration polyaluminum chloride (PACl) with high content of Alb or Alc. 2.52 mol/L PACl1 with 88% Alb and 2.38 mol/L PACl2 with 61% Alc were successfully prepared. Three coagulants, AlCl3, PACl1 and PACl2 were investigated on their hydrolysis behavior and speciation under different conditions. The effects of pH and dilution ratio on Al species distribution were investigated by ferron assay. Experimental result showed that pH had a significant effect on Al species distribution for the three coagulants. Dilution ratio had little effects on Alb and Alc distribution in whole dilution process except the beginning for PACl1 and PACl2. The results indicated that transformation of Al depends largely on their original composition. AlCl3 was the most unstable coagulant among these three coagulants during hydrolysis process. PACl1 and PACl2 with significant amounts of highly charged and stable polynuclear aluminum hydrolysis products were less affected by the hydrolysis conditions and could maintain high speciation stability under various conditions. PMID:19999987

Zhao, Changwei; Zhang, Jingbo; Luan, Zhaokun; Peng, Xianjia; Ren, Xiaojing

2009-01-01

259

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

Directory of Open Access Journals (Sweden)

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

Pavle Randjelovic

2001-03-01

260

Titanium doped silicon layers with very high concentration  

International Nuclear Information System (INIS)

Ion implantation of Ti into Si at high doses has been performed. After laser annealing the maximum average of substitutional Ti atoms is about 1018 cm-3. Hall effect measurements show n-type samples with mobility values of about 400 cm2/V s at room temperature. These results clearly indicate that Ti solid solubility limit in Si has been exceeded by far without the formation of a titanium silicide layer. This is a promising result toward obtaining of an intermediate band into Si that allows the design of a new generation of high efficiency solar cell using Ti implanted Si wafers

2008-07-01

 
 
 
 
261

Biofiltration of benzene contaminated air streams using compost-activated carbon filter media  

Energy Technology Data Exchange (ETDEWEB)

Three laboratory-scale biofilter columns were operated for 81 days to investigate the removal of benzene from a waste gas stream. The columns contain a mixture of yard waste and sludge compost as biomedia. Different amounts of granular activated carbon (GAC) are mixed with the compost in two of the three columns to evaluate the extent to which biofilter performance can be enhanced. The effects of different operating conditions on the performance of the removal of benzene from air were evaluated. More than 90% removal efficiency was observed for an influent benzene concentration of about 75 ppm and an air flow rate of 0.3 L/min. in all 3 columns under steady-state conditions. Under most cases of shock loading conditions, such as a sudden increase in the air flow rate, or the benzene concentration in the influent, the biofilters containing GAC provided higher removal efficiencies and more stable operation than the biofilter containing compost only.

Zhu, L.; Kocher, W.M. [Cleveland State Univ., OH (United States). Civil Engineering Dept.; Abumaizar, R.J. [Southern Methodist Univ., Dallas, TX (United States). Dept. of Mechanical Engineering

1998-12-31

262

Molecular motion and solvation of benzene in water, carbon tetrachloride, carbon disulfide and benzene: A combined molecular dynamics simulation and nuclear magnetic resonance study  

Science.gov (United States)

Benzene, dissolved in several solvents of varying viscosities and as a neat liquid, is investigated using both MD simulation techniques and NMR spectroscopy. Molecular motions-linear translation, angular rotation and reorientational motion-are studied and related to intermolecular interactions and to the microscopic solvation structure obtained from MD simulation. Self-diffusion coefficients are measured by Fourier transform pulse-gradient spin-echo NMR techniques. The reorientational rotational motion of benzene is studied using 2H NMR T1 relaxation measurements. The 2H T1 measurements also include benzene in solvents: hexane, cyclohexane, chloroform, dodecane and hexadecane. A special emphasis is on the anisotropy of benzene. Attempts are made to interpret the anisotropic behavior in terms of specific solute-solvent interactions and the solvation structure around benzene. Concerning the three solvents-water, carbon tetrachloride and carbon disulfide-a fairly clear and consistent picture emerges from both experimental and theoretical studies. The reorientational motion of benzene is found to be highly anisotropic in water, slightly less anisotropic in carbon tetrachloride, while it is nearly isotropic in carbon disulfide solution. MD simulations show some evidence for hydrogens of water approaching the ring region of benzene.

Laaksonen, Aatto; Stilbs, Peter; Wasylishen, Roderick E.

1998-01-01

263

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

264

Dosimetric studies in a facility with high concentrations of radon  

International Nuclear Information System (INIS)

In a coastal marsh area have high levels of radon found in some locations, one of them is a wastewater treatment plant, which far exceeds the recommended level in work zones. We present the results of the study for the evaluation of excess doses received by workers in that facility. (Author)

2011-01-01

265

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

266

High-efficiency Köhler photovoltaic concentrators with external light confinement  

Science.gov (United States)

Metal grid lines are a vital element in multijunction solar cells in order to take out from the cell the generated photocurrent. Nevertheless all this implies certain shadowing factor and thus certain reflectivity on cells surface that lowers its light absorption. This reflectivity produces a loss in electrical efficiency and thus a loss in global energy production for CPV systems. We present here an optical design for recovering this portion of reflected light, and thus leading to a system efficiency increase. This new design is based on an external confinement cavity, an optical element able to redirect the light reflected by the cell towards its surface again. It has been possible thanks to the recent invention of the advanced Köhler concentrators by LPI, likely to integrate one of these cavities easily. We have proven the excellent performance of these cavities integrated in this kind of CPV modules offering outstanding results: 33.2% module electrical efficiency @Tcell=25ºC and relative efficiency and Isc gains of over 6%.

Zamora, Pablo; Benítez, Pablo; Miñano, Juan C.; Li, Yang; Buljan, Marina

2011-09-01

267

An astigmatic corrected target-aligned heliostat for high concentration  

Energy Technology Data Exchange (ETDEWEB)

Conventional heliostats suffer from astigmatism for non-normal incidence. For tangential rays the focal length is shortened while for sagittal rays it is longer than the nominal focal length. Due to this astigmatism it is impossible to produce a sharp image of the sun, and the rays will be spread over a larger area. In order to correct this the heliostat should have different curvature radii along the sagittal and tangential direction in the heliostat plane just like a non axial part of a paraboloid. In conventional heliostats, where the first axis, fixed with respect to the ground, is vertical while the second, fixed with respect to the reflector surface, is horizontal, such an astigmatism correction is not practical because the sagittal and tangential directions rotate with respect to the reflector. We suggest an alternative mount where the first axis is oriented towards the target. The second axis, perpendicular to the first and tangent to the reflector, coincides with the tangential direction. With this mounting sagittal and tangential direction are fixed with respect to the reflector during operation. Therefore a partial astigmatism compensation is possible. We calculate the optimum correction and show the performance of the heliostat. We also show predicted yearly average concentrations

Zaibel, R.; Dagan, E.; Karni, J. [Solar Research Facility, The Weizmann Institute of Science, Rehovot (Israel); Ries, Harald [Ludwig-Maximilians-Universitaet, Sektion Physik, Munich (Germany)

1995-05-28

268

From benzene to muconaldehyde: Theoretical mechanistic investigation on some tropospheric oxidation channels  

Energy Technology Data Exchange (ETDEWEB)

In the tropospheric oxidation of benzene and methylated benzenes, unsaturated dicarbonyls are commonly detected products. Aldehydes are known to contribute on their own to some aspects of air pollution, and hexa-2,4-dien-1,6-dial (muconaldehyde) in particular is interesting because of its multiform toxicity. This study investigates the likelihood of some benzene oxidation steps and is especially focused on ring opening and generation of muconaldehyde.; With sufficiently high NO{sub x} concentration, O abstraction by NO from the cis peroxyl group in the 2-hydroxy-cyclohexadienyl peroxyl radical can play a role. In fact, it is shown to open a facile cascade of oxidation steps by first forming the 2-hydroxy-cyclohexadienyl oxyl radical. This intermediate is prone to ring opening via {beta}-fragmentation and generates the open-chain delocalized 6-hydroxy-hexa-2,4-dienalyl radical, in which one terminus is the first carbonyl group of the final dialdehyde. The second one can form either by simple H abstraction operated by O{sub 2} or by O{sub 2} addition followed by HOO{sup {sm{underscore}bullet}}elimination. The overall free-energy drop is estimated to be 48 kcal mol{sup {minus}1}. Exploration of other pathways, possibly playing a major role in yielding aldehydes in the case of low NO{sub x} concentration, indicates that only ring closure of the 2-hydroxy-cyclohexadienyl peroxyl radical to the [3.2.1] bicyclic endo-peroxy allyl radical intermediate is promising. In this case, however, the outcome of a subsequent ring opening can ultimately be the production of 1,2 and 1,4 dialdehydes (as direct oxidation of muconaldehyde itself can actually do).

Ghigo, G.; Tonachini, G.

1999-09-15

269

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

Energy Technology Data Exchange (ETDEWEB)

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 {mu}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 {mu}g/L to 2.0 {mu}g/L, the concentration of toluene varied from < 0.70 {mu}g/L to 3.24 {mu}g/L and the maximum value of xylenes observed was of 2.92 {mu}g/L. The seawater samples contaminated with BTX standard were exposed to ionizing radiation using a source of {sup 60}Co. 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)

Almeida, Kelly Cristina Santana de; Cardoso, Vanessa Miguel; Mori, Manoel Nunes; Duarte, Celina Lopes [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)]. E-mails: kellycsalmeida@ig.com.br; vcardose@usp.br; mnmori@ipen.br; clduarte@ipen.br

2007-07-01

270

High plasma uric acid concentration: causes and consequences  

Digital Repository Infrastructure Vision for European Research (DRIVER)

High plasma uric acid (UA) is a precipitating factor for gout and renal calculi as well as a strong risk factor for Metabolic Syndrome and cardiovascular disease. The main causes for higher plasma UA are either lower excretion, higher synthesis or both. Higher waist circumference and the BMI are associated with higher insulin resistance and leptin production, and both reduce uric acid excretion. The synthesis of fatty acids (tryglicerides) in the liver is associated with the de novo synthesis...

Oliveira, Erick Prado; Burini, Roberto Carlos

2012-01-01

271

High plasma uric acid concentration: causes and consequences  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract High plasma uric acid (UA) is a precipitating factor for gout and renal calculi as well as a strong risk factor for Metabolic Syndrome and cardiovascular disease. The main causes for higher plasma UA are either lower excretion, higher synthesis or both. Higher waist circumference and the BMI are associated with higher insulin resistance and leptin production, and both reduce uric acid excretion. The synthesis of fatty acids (tryglicerides) in the liver is associated with th...

de Oliveira Erick; Burini Roberto

2012-01-01

272

Numerical modelling of transient flows with high sediment concentrations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The main purpose of the present paper is to describe and discuss the development, validation and application of a numerical model designed to handle transient flows with high sediment transport rates. The model considers non-equilibrium transport (i.e. accounting for loading / unloading delay) and is numerically as well as physically totally coupled. The closure relations needed to evaluate the exchange fluxes between the fixed bottom and the flowing mixture (erosion and deposition rates) are...

Dewals, Benjamin; Erpicum, Se?bastien; Pirotton, Michel

2008-01-01

273

High plasma uric acid concentration: causes and consequences  

Directory of Open Access Journals (Sweden)

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

de Oliveira Erick

2012-04-01

274

Intercomparison of high-volume PM10 samplers at a site with high-particulate concentrations  

Energy Technology Data Exchange (ETDEWEB)

Commercially available high-volume PM10 samplers were intercompared at a site in Phoenix characterized by high concentrations of coarse particles. Over a 21-day period, Sierra Andersen 321A (SA 321A) samplers gave PM10 measurements 58% higher than the Wedding IP10 (WED) samplers and 16% higher than a SA 321A sampler that had an oil coating on the internal impaction surfaces of the inlet. WED samplers that were subjected to a simple brush-cleaning procedure after each sampling period gave PM10 results 16% higher than the WED samplers not subjected to cleaning. The oiled SA 321A sampler gave PM10 values 15% higher than the cleaned WED samplers. The results demonstrate that the SA 321A overestimates PM10 when sampling in an environment with high coarse-particle concentrations. The over collection results from pass-through of large particles, and can be minimized by oiling the internal impaction surfaces of the inlet. The WED sampler underestimates PM10 after several days of sampling in such an environment.

Purdue, L.J.; Rodes, C.E.; Rehme, K.A.; Holland, D.M.; Bond, A.E.

1986-01-01

275

Heterogeneous Photocatalytic Oxidation Removal of Gaseous Benzene over
TiO2/ACF Composite Prepared by Improved Sol-Gel Method
 

Digital Repository Infrastructure Vision for European Research (DRIVER)

TiO2/ACF composite was prepared by improved solª²gel method using Ti(OBu)4 as titanium source. TiO2 precursor was loaded on activated carbon fiber (ACF) by dip-coating method. X-ray diffraction (XRD), scanning electron microscopy (SEM) and N2 (77K) adsorption were used to characterize the obtained composite. High concentration gaseous benzene in a staticª²mode photocatalytic reactor was used as model comp...

Liu Shou-xin, Liu Zheng-feng

2009-01-01

276

Recent testing of secondary concentrators at NREL`s high-flux solar furnace  

Energy Technology Data Exchange (ETDEWEB)

Several tests have been completed on new secondary concentrators at the High-Flux Solar Furnace (HFSF) at the National Renewable Energy Laboratory (NREL). The first test measured the power from the exit of a High-Index secondary that achieves an average concentration of 50,000 suns. The second concentrator tested pumped an Nd:YAG laser crystal. The concentrator designs are presented, along with data from on-sun testing at the HFSF.

Jenkins, D.; Winston, R.; O`Gallagher, J. [Univ. of Chicago, IL (United States); Bingham, C.; Lewandowski, A.; Pitts, R.; Scholl, K. [National Renewable Energy Lab., Golden, CO (United States)

1996-12-31

277

Occupational exposures associated with petroleum-derived products containing trace levels of benzene.  

Science.gov (United States)

Benzene may be present as a trace impurity or residual component of mixed petroleum products due to refining processes. In this article, the authors review the historical benzene content of various petroleum-derived products and characterize the airborne concentrations of benzene associated with the typical handling or use of these products in the United States, based on indoor exposure modeling and industrial hygiene air monitoring data collected since the late 1970s. Analysis showed that products that normally contained less than 0.1% v/v benzene, such as paints and paint solvents, printing solvents and inks, cutting and honing oils, adhesives, mineral spirits and degreasers, and jet fuel typically have yielded time-weighted average (TWA) airborne concentrations of benzene in the breathing zone and surrounding air ranging on average from <0.01 to 0.3 ppm. Except for a limited number of studies where the benzene content of the product was not confirmed to be <0.1% v/v, airborne benzene concentrations were also less than current occupational exposure limits (e.g., threshold limit value of 0.5 ppm and permissible exposure limit of 1.0 ppm) based on exceedance fraction calculations. Exposure modeling using Monte Carlo techniques also predicted 8-hr TWA near field airborne benzene concentrations ranging from 0.002 to 0.4 ppm under three hypothetical solvent use scenarios involving mineral spirits. The overall weight-of-evidence indicates that the vast majority of products manufactured in the United States after about 1978 contained <0.1% v/v benzene, and 8-hr TWA airborne concentrations of benzene in the workplace during the use of these products would not have been expected to exceed 0.5 ppm under most product use scenarios. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource: a document containing exposure modeling scenarios and results, historical benzene content of petroleum-derived products, and air monitoring results.]. PMID:18615290

Williams, Pamela R D; Panko, Julie M; Unice, Ken; Brown, Jay L; Paustenbach, Dennis J

2008-09-01

278

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.)

1984-01-01

279

Percutaneous absorption of benzene: research and regulation  

Energy Technology Data Exchange (ETDEWEB)

This article attempts to review several aspects of the regulation of benzene in the United States with an emphasis on percutaneous penetration (absorption of benzene into the skin). The author's purpose is not merely to highlight a regulatory crisis encountered by the American rubber industry, but to also provide a vivid example of how toxic substances and carcinogens are regulated in the United States. This paper, therefore, will address the following three areas: first, a chronology of benzene regulation, both voluntary and mandatory; second, a brief review of the early literature on the percutaneous penetration of benzene; and third, a summary of recent studies on benzene penetration which were conducted under the auspices of the American rubber industry.

Ryan, F.T.

1981-01-01

280

Comparison of measurement methods for benzene and toluene  

Science.gov (United States)

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

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

 
 
 
 
281

Viscosity controlled production of high-concentration backfill pastes  

Energy Technology Data Exchange (ETDEWEB)

The German mining industry uses different residues for backfilling and stowing. A hydraulic pipe conveying technology for these materials has shown advantages for the transportation into the mine. A development of the DMT, a bypass pipe-viscometer, has been the key technology for the successful installation of viscosity controlled paste production for hydraulic backfill. The system is able to analyse on-line difficult, sticky and abrasive substances and determine their non-Newtonian flow properties. Because the system measures real physical values it is in a position to pre-calculate process relevant parameters like the pressure drop of the backfilling paste in the conveying pipeline. Newer types of the viscometer system also measures the slurry density and calculate its composition. These systems have proven a success controlling backfill paste production plants. They offer a secure prevention of pipeline plugging and a production of high quality backfill pastes with a water content as low as possible. 3 refs., 10 figs.

Hollinderbaeumer, E.W.; Mez, W. [DMT-Gesellschaft fuer Forschung und Pruefung mbH, Essen (Germany)

1998-07-01

282

Method of high resolution partial area scan involving concentrated high density material outside the partial area  

International Nuclear Information System (INIS)

A method of minimizing a streaking effect found in reconstructed images obtained from high resolution ct scanning of a small scan circle that corresponds to a limited region of interest, such as portions of the spinal cord of a patient, particularly in scans that include concentrated high density material, such as bone, situated outside the small scan circle. The approximate range of view angles that will project bone from outside the limited region of interest is determined. Detectors corresponding to the determined region are selected out. The projection data acquired by the selected detectors is filtered. The filtering is accomplished by convolving the projection data with a preselected filter function or in machine implemented form by passing the electrical signal representing the projection data through a low pass filter

1982-01-01

283

Dynamical and structural properties of benzene in supercritical water  

Science.gov (United States)

We have employed an anisotropic united atom model of benzene (R. O. Contreras, Ph.D. thesis, Universitat Rovira i Virgili 2002) that reproduces the quadrupolar moment of this molecule through the inclusion of seven point charges. We show that this kind of interaction is required to reproduce the solvation of these molecules in supercritical water. We have computed self-diffusion coefficient and Maxwell-Stefan coefficients as well as the shear viscosity for the mixture water-benzene at supercritical conditions. A strong density and composition dependence of these properties is observed. In addition, our simulations are in qualitative agreement with the experimental evidence that, at medium densities (0.6 g/cm3 and 673 K), almost half of the benzene molecules have one hydrogen bond with water molecules. We also observe that these bonds are longer lived than the corresponding hydrogen bonds between water molecules. Similarly, we obtain an important reduction of the dielectric constant of the mixture with the increment of the amount of benzene molecules at medium and high densities.

Nieto-Draghi, Carlos; Bonet Àvalos, Josep; Contreras, Oliver; Ungerer, Philippe; Ridard, Jacqueline

2004-12-01

284

Control of the Diatropic ? Ring Current in Strained Benzenes: Effects of Annelation with Cyclopropa, Cyclobuta and Cyclobutadieno Clamping Groups  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Direct visualization of the ð current density maps of highly strained annelated benzenes containing cyclopropa, cyclobuta, and cyclobutadieno clamps, alone and in combination, using a reliable distributed-origin, coupled Hartree-Fock method, shows the robustness of the classical benzene diatropic ð ring current. When only saturated clamps are used, the benzene ring current is essentially unchanged. In contrast, annelation with one or more cyclobutadieno clamps disrupts the be...

Soncini, A.; Havenith, R. W. A.; Fowler, P. W.; Jenneskens, L. W.; Steiner, E.

2002-01-01

285

Copepod hatching success in marine ecosystems with high diatom concentrations.  

DEFF Research Database (Denmark)

Diatoms dominate spring bloom phytoplankton assemblages in temperate waters and coastal upwelling regions of the global ocean. Copepods usually dominate the zooplankton in these regions and are the prey of many larval fish species. Recent laboratory studies suggest that diatoms may have a deleterious effect on the success of copepod egg hatching. These findings challenge the classical view of marine food-web energy flow from diatoms to fish by means of copepods. Egg mortality is an important factor in copepod population dynamics, thus, if diatoms have a deleterious in situ effect, paradoxically, high diatom abundance could limit secondary production. Therefore, the current understanding of energy transfer from primary production to fisheries in some of the most productive and economically important marine ecosystems may be seriously flawed. Here we present in situ estimates of copepod egg hatching success from twelve globally distributed areas, where diatoms dominate the phytoplankton assemblage. We did not observe a negative relationship between copepod egg hatching success and either diatom biomass or dominance in the microplankton in any of these regions. The classical model for diatom-dominated system remains valid.

Irigoien, Xabier; Harris, Roger P

2002-01-01

286

[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

287

Apparent Benzene Solubility in Tetraphenylborate Slurries  

International Nuclear Information System (INIS)

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

1997-01-01

288

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

International Nuclear Information System (INIS)

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

2007-03-01

289

Continuous ethanol production at high glucose concentrations by a passively immobilized Zymomonas mobilis system  

Energy Technology Data Exchange (ETDEWEB)

The effect of high glucose concentrations on continuous ethanol production by passively immobilized Zymomonas mobilis cells has been studied. High effluent ethanol concentrations always led to low productivities. The maximum ethanol concentration attained was 92.8 g/l (98% glucose conversion) at a dilution rate of 0.14 h/sup -1/ with 200 g/l glucose medium. The observed enhancement of cell immobilization in the fibrous support at high glucose concentrations in the feed input seems to be related to the formation of bacterial filaments. (orig.).

Castellar, M.R.; Borrego, F.; Canovas, M.; Manjon, A.; Iborra, J.L.

1989-09-01

290

Optimizing the form of high voltage photoconverters for operation with solar radiation concentrators  

Energy Technology Data Exchange (ETDEWEB)

High voltage (VN) photoconverters are studied in order to optimize their dimensions and form in developing highly effective solar power modules with concentrators based on a Fresnel lens and other types.

Yepifanov, M.S.; Unishkov, V.A.

1983-01-01

291

Pharmacokinetics of benzene in a human after exposure at about the permissible limit  

Energy Technology Data Exchange (ETDEWEB)

This limited range of experimental human exposure indicates that: 1. In the single experimental subject, the amount of benzene retained in the body 10 hours and more after exposure depends on the multiple of the concentration and duration of exposure. 2. At concentrations about the threshold limit value, the presence of other hydrocarbons does not affect the retention or elimination of benzene. 3. The amount of benzene retained in the body for 10 or more hours is dependent on the energy expenditure of the subject during exposure. There is reason to think that elimination after exposure is similarly affected. 4. While the principal route for elimination of benzene is the metabolite, conjugated phenol, in urine, the proportion eliminated in breath depends on the duration of exposure in the 1- to 8-hour range. 5. Three or four distinct compartments for retaining benzene are apparent and these may be identified with specific groups of organs in the body. 6. Mathematical modelling of the system can provide a reasonably accurate representation of benzene behavior in the body, and should enable dosage to individual or groups of organs to be estimated after occupational exposure. 7. Diurnal variation in the elimination of benzene after exposure may introduce a factor of uncertainty of about two into the prediction of exposure from biological monitoring. 8. Patterns of retention and elimination of toluene are very similar to those of benzene, though the principal metabolite in urine is different, and there may be a limit to the maximum amount that can be excreted by that route due to the relatively low solubility of hippuric acid in aqueous solutions.

Sherwood, R.J.

1988-01-01

292

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

293

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

294

Management of benzene emissions from glycol dehydrators in the natural gas industry  

Energy Technology Data Exchange (ETDEWEB)

This presentation discussed the control and effective management of benzene emissions from glycol dehydrators used in the natural gas industry to remove water from natural gas. The upstream natural gas industry has agreed to reduce benzene emissions from glycol dehydration operations in order to minimize the health risk related to benzene emissions. A target of 90 per cent reduction from the 1995 national emissions baseline has been established for the year 2005. During the processing of natural gas, a portion of benzene is emitted to the atmosphere which, due to its toxicity, is a cause for concern from both an occupational health and public health perspective. Benzene emissions can be controlled in several ways. In 1995, Environment Canada formed a Working Group on Benzene Emissions from Glycol Dehydrators which agreed to implement a voluntary program of emissions limits and reporting criteria. To date, the program has been successful. Reduction in total benzene emissions surpassed targets set for the 1995 to 1999 period (54 per cent versus 30 per cent). A high level of industry compliance was also observed. 23 refs., 4 tabs.

Johnston, B. [Burlington Resources Canada Energy Ltd., Calgary, AB (Canada)

2000-07-01

295

Modeling benzene NAPL removal during air sparging  

Energy Technology Data Exchange (ETDEWEB)

Air sparging is a commonly used enhanced remedial tool for in-situ aquifer remediation. In an attempt to test assumptions commonly made in air sparging models, a lab-scale reactor with two isolated and controlled vertical channels of air through saturated porous media was used to study air sparging of a benzene NAPL under different airflow rates in the absence of retardation and groundwater flow. A simple dissolution-diffusion-volatilization (DDV) model was constructed to compare experimental results with the modeled results. Increasing the airflow rate from 45 mL/min to 125 mL/min had little to no effect on mass removal or the estimated volatilization or dissolution mass transfer rate constants when using a simple dissolution-diffusion-volatilization (DDV) model. This result was similar to that of many other researchers. The DDV model was, however unable to predict increased concentrations above the source zone in the aqueous phase. Furthermore, it produced predictions of a longer lag time for volatilization than experimentally determined. These results suggest that advection and dispersion may not only be solely caused by regional groundwater flow, but also momentum transfer from the advecting air.

Rogers, S.W.; Ong, S.K.

1999-07-01

296

EPR study of Gallium atoms in benzene  

Energy Technology Data Exchange (ETDEWEB)

An EPR study of a Ga atom matrix isolated in benzene at 77 K has revealed the presence of a paramagnetic species with the magnetic parameters {alpha}{sub zz}(69) = 256 MHz, {alpha}{sub xx}(69) = 270 MHz, {alpha}{sub yy}(69) = 284 MHz, {alpha}{sub zz}(71) = 325 MHz, {alpha}{sub xx}(71) = 343 MHz, {alpha}{sub yy}(71) = 361 Mhz, g{sub zz} = 1.9970, g{approximately}{sub xx} = 1.9750, and g{sub yy} = 1.9350. These parameters are consistent with a trapped atom or a weak Ga-benzene complex that has had the degeneracy of the Ga p orbitals lifted by interaction with the benzene matrix. This contrasts with Al in benzene which gives a mononuclear monoligand complex, Al(C{sub 6}H{sub 6}), with quite strong bonding between the metal atom and the ligand.

Howard, J.A.; Joly, H.A.; Mile, B.; Sutcliffe, R. (National Research Council of Canada, Ottawa, Ontario (Canada))

1991-09-05

297

Recommended sublimation pressure and enthalpy of benzene  

International Nuclear Information System (INIS)

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

2014-01-01

298

Potassium 2-iodo-benzene-sulfonate monohydrate.  

Science.gov (United States)

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

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

2008-01-01

299

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...the sample or clarifying with a clarification kit. 3. Apparatus. 3.1. Liquid chromatograph equipped with a UV detector. 3.2. HPLC Column that will separate benzene from other components in the bulk sample being analyzed. The...

2010-07-01

300

Differential regulation of cation transport of vascular smooth muscle cells in a high glucose concentration milieu.  

Science.gov (United States)

To gain new insights into the pathogenesis of diabetic angiopathy, the influence of high glucose concentration on cation transport of vascular smooth muscle cell (VSMC) membrane was investigated by measuring Na, K and Ca transport in serially passaged cultured VSMC. (1) Na-K pump activity, described as ouabain sensitive 86Rb uptake, and Na-K cotransport, described as bumetanide sensitive 86Rb washout of VSMC, grown in high glucose concentration medium (460 mg/dl), was lower than that grown in normal glucose concentration medium (100 mg/dl). A smaller 5-N,N-hexamethylene amiloride (HMA) sensitive 22Na uptake (Na-H antiport) in high glucose concentration medium. accounted for this difference. (2) 45Ca uptake was also smaller in VSMC cultured in high glucose concentration medium. However, the washout rate constant for 45Ca was comparable between high and normal glucose cultured VSMC. (3) Both intracellular concentration of Na and cytosolic free Ca concentration concentration ([Ca]i) of high glucose cultured VSMC were greater than normal glucose cultured VSMC. (4) Intracellular water volume based on the equilibrium distribution of 3-O-methyl-[14C]glucose was not different between normal and high glucose cultured VSMC. It is concluded that VSMC grown in high glucose concentration milieu manifests a decreased Na-K, and Ca transport in conjunction with an increase in intracellular concentration of Na and [Ca]i. These results suggest that high glucose, per se, may alter membrane permeability to cations, possibly leading to changes in VSMC contractility and/or proliferation. This abnormality seen in the diabetic state may closely link to the pathogenesis of diabetic angiopathy, thus as a result risking hypertension and vascular disease. PMID:7956712

Kuriyama, S; Tokudome, G; Tomonari, H; Utsunomiya, Y; Matsui, K; Hashimoto, T; Sakai, O

1994-06-01

 
 
 
 
301

Radium-226 concentration in spring water sampled in high radon regions  

International Nuclear Information System (INIS)

Water 226Ra concentration in springs was measured in regions with high indoor radon: Ural, North Caucasus (Russia), Niska Banja (Serbia), Piestany (Slovakia), and Issyk-Kul (Kyrgyzstan). This paper presents the results for 226Ra concentration above 0.03 Bq l-1. Radium in water could indicate indoor radon problem in the region and water investigation is useful at the initial stage of radon survey. Even low 226Ra concentration in water (0.1-0.6 Bq l-1) caused high 226Ra activity in travertine (up to 1500 Bq kg-1), which resulted in indoor radon concentration above 2000 Bq m-3 (Niska Banja).

2008-06-22

302

Radium-226 concentration in spring water sampled in high radon regions.  

Science.gov (United States)

Water (226)Ra concentration in springs was measured in regions with high indoor radon: Ural, North Caucasus (Russia), Niska Banja (Serbia), Piestany (Slovakia), and Issyk-Kul (Kyrgyzstan). This paper presents the results for (226)Ra concentration above 0.03 Bq l(-1). Radium in water could indicate indoor radon problem in the region and water investigation is useful at the initial stage of radon survey. Even low (226)Ra concentration in water (0.1-0.6 Bq l(-1)) caused high (226)Ra activity in travertine (up to 1500 Bq kg(-1)), which resulted in indoor radon concentration above 2000 Bq m(-3) (Niska Banja). PMID:19853463

Onishchenko, Aleksandra; Zhukovsky, Michael; Veselinovic, Nenad; Zunic, Zora S

2010-01-01

303

Lithium-Mediated Benzene Adsorption on Graphene and Graphene Nanoribbons  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 charge transfer from th...

2013-01-01

304

(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 results, and on the contrary, they show a relatively lower selectivity and extraction capacity for benzene than [MMIM][DMP].

2012-06-01

305

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

306

Urinary 1-hydroxypyrene concentrations in coke oven workers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

1998-01-01

307

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2004-05-26

308

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 (d...

2007-01-01

309

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 (d...

2007-01-01

310

Radiolysis of Aqueous Benzene Solutions  

International Nuclear Information System (INIS)

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

1964-01-01

311

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Fujii, S.; Beutler, E.

1985-01-01

312

Concentrations of high density lipoprotein cholesterol, triglycerides, and total cholesterol in ischaemic heart disease.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

OBJECTIVE--To assess the roles of serum concentrations of total cholesterol, high density lipoprotein cholesterol, and triglycerides in predicting major ischaemic heart disease. DESIGN--Men recruited for the British regional heart study followed up for a mean of 7.5 years. SETTING--General practices in 24 British towns. PATIENTS--7735 Middle aged men. END POINT--Predictive value of serum concentrations of lipids. MEASUREMENTS AND MAIN RESULTS--At initial screening serum concentrations of tota...

Pocock, S. J.; Shaper, A. G.; Phillips, A. N.

1989-01-01

313

Influence of growth and high mould concentration on the pressure drop in solid state fermentations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

#Aspergillus niger$ was grown on Amberlite IRA-900 imbibed with a solution containing high concentrations of sucrose (Si = 100, 200, 300 and 400 g/litre) in static aerated fermentors. Growth was followed in dry biomass, biomass protein, CO2 production and pressure drop (DP). The DP allowed the monitoring of germination, vegetative growth, militation and the onset of sporulation for the four concentrations of sucrose studied. Concentrations up to 103 mg dry biomass/g dry support were obtained ...

Auria, Richard; Ortiz, I.; Villegas, E.; Revah, S.

1995-01-01

314

[Value of immunoassay of hCG for the determination of high plasma concentrations].  

Science.gov (United States)

The serum concentration of human chorionic gonadotrophin is higher in trisomy 21 than in normal pregnancy. Our study aimed at comparing 17 commercial kits, both those for measuring high concentrations and others for diagnosis and initial follow-up of pregnancy under specific conditions, ie for measuring hCG concentrations between weeks 14 and 18 of pregnancy. All kits were satisfactory; however, usual values for the gestational weeks concerned need to be established for each reagent. PMID:7574095

Revol, A; Badonnel, Y; Bugugnani, M J; Delvigne, L; Fiet, J; Lacroix, I; Patricot, M C

1995-01-01

315

Incomplete Ion Dissociation Underlies the Weakened Attraction between DNA Helices at High Spermidine Concentrations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have investigated the salt sensitivity of the hexagonal-to-cholesteric phase transition of spermidine-condensed DNA. This transition precedes the resolubilization of precipitated DNA that occurs at high spermidine concentration. The sensitivity of the critical spermidine concentration at the transition point to the anion species and the NaCl concentration indicates that ion pairing of this trivalent ion underlies this unusual transition. Osmotic pressure measurements of spermidine salt sol...

Yang, Jie; Rau, Donald C.

2005-01-01

316

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2009-01-01

317

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

International Nuclear Information System (INIS)

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

2008-05-01

318

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

319

Advanced process development for high reflector coatings on solar concentrator panels. Final letter report  

Energy Technology Data Exchange (ETDEWEB)

Objectives were to develop and demonstrate the manufacturing process for vacuum deposition of low-cost thin-film high reflectance coatings onto large solar concentrator panels; demonstrate thin-film deposition processes for commercialization of this technology by United Solar Technologies (UST); apply reflective coatings to solar concentrator panels for prototype application by UST.

Martin, P.M.; Stewart, C.D.; Bennett, W.D.; Johnston, J.W.

1996-10-01

320

Leed structural studies of benzene monolayers on Rh(111) with and without CO coadsorption  

International Nuclear Information System (INIS)

Benzene, molecularly adsorbed on the Rh(111) single crystal surface, presents several periodically ordered arrangements, as a function of the relative amount of coadsorbed CO. The following Low Energy Electron Diffraction (LEED) patterns are observed: (2 ? 3 x 3) rect in the absence of CO, c(2 ? 3 x 4) rect for a 1:1 ratio of CO to benzene, and (3 x 3) for a 2:1 ratio. The CO to benzene ratios were obtained by High Resolution Electron Energy Loss Spectroscopy and Thermal Desorption Spectroscopy. The c(2 ? 3 x 4) rect structure has been solved in detail by a LEED intensity analysis: it consists of a strongly distorted benzene and an elongated CO in a three fold hollow site. The two other ordered structures are at present the subject of LEED intensity analyses

1986-01-01

 
 
 
 
321

The effect of substrate concentration fluctuation on the performance of high-rate denitrifying reactor.  

Science.gov (United States)

A high-rate denitrifying process is sensitive to the operation conditions and the substrate concentration fluctuation can lead to the deterioration or even collapse of process performance. The results of this study showed that the effect of substrate concentration fluctuation on the high-rate denitrification process was related to the substrate concentration and shock duration. The effect of substrate concentration was greater than that of shock duration and nitrate conversion was more sensitive than methanol conversion. The response of denitrification performance was related to the loading saturation (maximum loading rate/loading capacity ratio). When the loading saturation was lower than 32%, the high-rate denitrification process could stay in pseudo steady state, otherwise it would easily lose stability. The response of denitrification performance could be divided into three periods. The performance deterioration of high-rate denitrifying process could be attributed to the overload trigger and the toxicity of free nitrous acid. PMID:24971944

Li, Wei; Zheng, Ping; Zhang, Jiqiang; Shan, Xiaoyu; Wang, Zhiyao; Zhang, Meng

2014-09-01

322

Analysis of Pleural Effusions from Rats Exposed to High Concentrations of Oxygen.  

Science.gov (United States)

Pleural effusions from rats exposed to high concentrations of oxygen for periods of up to 96 hr. were analyzed by routine clinical chemical methods. When compared to control rat serum, the values for glutamic oxalacetic transaminase, the albumin/globulin ...

F. R. Robinson A. A. Thomas L. Rendon

1968-01-01

323

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

2013-08-01

324

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

1980-10-01

325

High-performance liquid chromatography measurement of antimicrobial concentrations in polymorphonuclear leukocytes.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

High-performance liquid chromatography was used to determine the penetration of 19 antimicrobial agents into human polymorphonuclear leukocytes. The ratios of the intracellular concentration to the extracellular concentration of ampicillin, piperacillin, cefazolin, ceftizoxime, cefpimizole, and ceftazidime were all less than 0.6. Lincomycin showed a high intracellular-to-extracellular ratio (3.0), while clindamycin achieved a ratio of 15.5, which was the highest ratio of all of the 19 tested ...

Koga, H.

1987-01-01

326

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 parti...

2013-01-01

327

Polymer-stabilized graphene dispersions at high concentrations in organic solvents for nanocomposite production  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We demonstrate a simple and effective technique for dispersing pristine (unfunctionalized) graphene at high concentrations in a wide range of organic solvents by use of a stabilizing polymer (polyvinylpyrrolidone, PVP). These polymer-stabilized graphene dispersions are shown to be highly stable and readily redispersible even after freeze-drying. This technique yields significantly higher graphene concentrations as compared to prior studies. Excellent enhancement in thermal c...

Wajid, Ahmed S.; Das, Sriya; Irin, Fahmida; Ahmed, H. S. Tanvir; Shelburne, John L.; Parviz, Dorsa; Fullerton, Robert J.; Jankowski, Alan F.; Hedden, Ronald C.; Green, Micah J.

2011-01-01

328

Isobaric vapor-liquid equilibria for ethanol + benzene + magnesium chloride  

Energy Technology Data Exchange (ETDEWEB)

The effect of salts on the vapor-liquid equilibrium (VLE) of solvent mixtures has been of considerable interest in separation processes. Salts may be added to a system to alter the VLE behavior in the extractive or azeotropic distillation. The effect of magnesium chloride on the vapor-liquid equilibria for the system ethanol + benzene at different salt concentrations was studied at 100.0 kPa. The measured mole fractions in the vapor phase were correlated by the Johnson-Furter and Sada models. Thermodynamic consistency was checked by the restricted range area test with satisfactory results.

Chen, W.C.; Tsai, F.N. [National Cheng Kung Univ., Tainan (Taiwan, Province of China). Dept. of Chemical Engineering

1995-09-01

329

Derivation of reference concentration values in foods for Brazilian high background radiation areas  

International Nuclear Information System (INIS)

Aiming the establishment of Brazilian high background radiation area baseline data, 226Ra, 228Ra, 210Pb, 232Th, 228Th and 238U concentrations in foodstuffs arose from Brazilian high natural radiation areas were gathered, generating a databank containing concentration of radionuclides in 548 samples, 1871 single concentration measurements. Radionuclide concentration values in food vary widely because of the soil heterogeneity. In most analyzed samples the highest concentrations were found for 228Ra, followed by 226Ra, 210Pb, 228Th, 238U and 232Th. Differences among radionuclide concentrations in potato and carrot, kale and other leafy vegetables as well as among chicken, beef and pork were observed, showing that the joining of food in categories aiming comparison among concentrations can be meaningless. The origin of the food seems not play important role concerning the radionuclide concentration in it, since it was not found significant differences among the radionuclide concentrations in samples of a same food from the different areas. Reference values for some foodstuffs could be derived and in general the values can exceed by orders of magnitude those derived for temperate clime normal background areas. (author)

2000-10-15

330

Incomplete ion dissociation underlies the weakened attraction between DNA helices at high spermidine concentrations.  

Science.gov (United States)

We have investigated the salt sensitivity of the hexagonal-to-cholesteric phase transition of spermidine-condensed DNA. This transition precedes the resolubilization of precipitated DNA that occurs at high spermidine concentration. The sensitivity of the critical spermidine concentration at the transition point to the anion species and the NaCl concentration indicates that ion pairing of this trivalent ion underlies this unusual transition. Osmotic pressure measurements of spermidine salt solutions are consistent with this interpretation. Spermidine salts are not fully dissociated at higher concentrations. The competition for DNA binding among the fully charged trivalent ion and the lesser charged complex species at higher concentrations significantly weakens attraction between DNA helices in the condensed state. This is contrary to the suggestion that the binding of spermidine at higher concentrations causes DNA overcharging and consequent electrostatic repulsion. PMID:15980178

Yang, Jie; Rau, Donald C

2005-09-01

331

Adsorption and diffusion of benzene in the nanoporous catalysts FAU, ZSM-5 and MCM-22: a molecular dynamics study.  

Science.gov (United States)

Molecular dynamics (MD) simulations of benzene in siliceous zeolites (FAU, ZSM-5, and MCM-22) were performed at loadings of 1, 2, 4, 8, and 16 molecules per supercell. The potential energy functions for these simulations were constructed in a semi-empirical way from existing potentials and experimental energetic data. The MD simulations were employed to analyze the dynamic properties of the benzene-zeolite systems. The adsorption energies of benzene/siliceous zeolite complexes increase with increasing loading number, due to the intermolecular attraction between benzene molecules. The self-diffusion coefficient of benzene in siliceous zeolites decreases with increasing loading due to the steric hindrance between the sorbates passing each other. From the zeolite-benzene radial distribution functions it was found that the benzene molecules are relatively far from each other, about 5.2A for siliceous FAU, 5.2A for siliceous ZSM-5, and 4.8A for siliceous MCM-22. In the case of FAU, the benzene molecules prefer to be adsorbed parallel to the surface of the sodalite cage above the six-membered-ring. In ZSM-5, we found a T-structure of the benzene molecules at loadings 2, 4, and 8 molecules per supercell. At loadings of 16 molecules per supercell, the molecules are lined up along the straight channel and their movement is highly correlated. For MCM-22 we found adjacent benzene molecules at a loading of 4 molecules with an orientation similar to the stacked conformation of benzene dimer in the gas phase. PMID:16288979

Rungsirisakun, Ratana; Nanok, Tanin; Probst, Michael; Limtrakul, Jumras

2006-03-01

332

Multi-scale simulation on solid benzene  

Science.gov (United States)

Solid Benzene is used in organic semiconductors for photovoltaics, which often include pi-conjugated systems. We use MD simulations method to explore the relationship between the structure and interaction energy of two kinds of solid benzene, with the Pbca and P21c crystallgraphic structures respectively. Simple relevant force fields (PCFF and CVFF) are examined with regard to their performance on the structure and energetics of benzene dimers and benzene crystals which serve as well characterized model systems. However, MD simulations cannot get the transport properties. So the combination of reliable classical atomistic simulations and quantum-mechanical methods is needed to understand the dynamics of charge transport and self-assembly processes involving pi-conjugated oligomers and polymers. As alternative and accurate models, we explore atomistic models with additional sites which represent the location of the pi electrons and are characterized by suitable charges and van-der-Waals parameters. With these parameters, it will be possible to reproduce the dimer geometries and energies, the crystal structure of solid benzene, as well as pi-stacking forces and free energies for similar systems.

Liu, Hua; Heinz, Hendrik

2009-03-01

333

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

334

The leap-frog effect of ring currents in benzene.  

Science.gov (United States)

Symmetry arguments show that the ring-current model proposed by Pauling, Lonsdale, and London to explain the enhanced diamagnetism of benzene is flawed by an intrinsic drawback. The minimal basis set of six atomic 2p orbitals taken into account to develop such a model is inherently insufficient to predict a paramagnetic contribution to the perpendicular component of magnetic susceptibility in planar ring systems such as benzene. Analogous considerations can be made for the hypothetical H(6) cyclic molecule. A model allowing for extended basis sets is necessary to rationalize the magnetism of aromatics. According to high-quality coupled Hartree-Fock calculations, the trajectories of the current density vector field induced by a magnetic field perpendicular to the skeletal plane of benzene in the pi electrons are noticeably different from those typical of a Larmor diamagnetic circulation, in that (i) significant deformation of the orbits from circular to hexagonal symmetry occurs, which is responsible for a paramagnetic contribution of pi electrons to the out-of-plane component of susceptibility, and (ii) a sizable component of the pi current density vector parallel to the inducing field is predicted. This causes a waving motion of pi electrons; streamlines are characterized by a "leap-frog effect". PMID:11866615

Ligabue, Andrea; Soncini, Alessandro; Lazzeretti, Paolo

2002-03-01

335

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.

2009-07-15

336

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

337

Study on high concentration solar concentrator using a Fresnel lens with a secondary concentrator; Fresnel lens to niji shukokei wo mochiita solar chemistry yo kobairitsu shukokei ni kansuru kenkyu  

Energy Technology Data Exchange (ETDEWEB)

A high concentration light collection system for solar chemistry was devised by using an inexpensive Fresnel lens in a primary concentration system and a conical type concentrator in a secondary concentration system. A Fresnel lens alone would not achieve sufficiently high light collecting magnification to attain high temperatures because of restrictions in the opening angle as seen from a focus. Therefore, a secondary concentration system was installed on a focus for an attempt of stopping. Reflection plane of a three-dimensional compound parabolic concentrator (CPC) is a rotary parabolic plane, whose process is expensive because of its surface processing accuracy. Therefore, a conical type concentrator was employed as a secondary concentration system. This system may not be capable of achieving as high concentration as in the CPC, but its shape is simple and it is inexpensive. In its optimization, a complete black body surface placed in vacuum atmosphere was hypothesized as a light concentrating part for the secondary concentration system to calculate heat collecting efficiencies at respective temperature settings. Using simultaneously the secondary concentration system, rather than collecting heat by using a Fresnel lens alone, has attained as high value as from 5.99% (500 degC) to 43.47% (1400 degC). Economical high-temperature heat collection of solar chemistry level may be possible by using a Fresnel lens and a conical secondary concentration system. 1 ref., 7 figs., 2 tabs.

Aihara, T.; Suzuki, A.; Fujibayashi, K. [Tokyo University of Agriculture and Technology, Tokyo (Japan)

1997-11-25

338

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 adsorption is weaker and the underlying mechanism is under study. (author)

2009-01-01

339

Trace element concentrations and gastrointestinal parasites of Arctic terns breeding in the Canadian High Arctic.  

Science.gov (United States)

Baseline data on trace element concentrations are lacking for many species of Arctic marine birds. We measured essential and non-essential element concentrations in Arctic tern (Sterna paradisaea) liver tissue and brain tissue (mercury only) from Canada's High Arctic, and recorded the presence/absence of gastrointestinal parasites during four different phases of the breeding season. Arctic terns from northern Canada had similar trace element concentrations to other seabird species feeding at the same trophic level in the same region. Concentrations of bismuth, selenium, lead and mercury in Arctic terns were high compared to published threshold values for birds. Selenium and mercury concentrations were also higher in Arctic terns from northern Canada than bird species sampled in other Arctic areas. Selenium, mercury and arsenic concentrations varied across the time periods examined, suggesting potential regional differences in the exposure of biota to these elements. For unknown reasons, selenium concentrations were significantly higher in birds with gastrointestinal parasites as compared to those without parasites, while bismuth concentrations were higher in Arctic terns not infected with gastrointestinal parasites. PMID:24472719

Provencher, J F; Braune, B M; Gilchrist, H G; Forbes, M R; Mallory, M L

2014-04-01

340

Effect of high dietary sulfur on enzyme activities, selenium concentrations and body weights of cattle  

Energy Technology Data Exchange (ETDEWEB)

This study was designed to assess the effect of a moderate increase in dietary sulphur (S) in cattle. Twelve animals were initially fed a basal concentrate (S=0.2%) and then divided into two groups; one fed basal and the other high S (S=0.75%) concentrates. Health, body weight gains, and activities of erythrocyte enzymes: glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), glucose-6-phospate dehydrogenase (G6PD), acetylcholinesterase (AChE), plasma- asparate aminotransferase (AST), and whole blood concentrations of selenium (Se) were monitored at various stages of the study. Marked increases in the activities of GSH-Px, SOD and G6PD from the pretrial values were observed upon initial feeding of basal concentrate diet. Sex related differences were not evident in enzyme activities and Se concentrations of the blood. A high linear correlation (r=0.92) between averages of GSH-Px activity and Se concentration of blood was observed in both sexes. Increasing the amount of S in the concentrate diet (from 0.2 to 0.75%) did not produce any statistically significant change in enzyme activities and Se concentrations, body weight gains, and health of the cattle during the 85 days feeding period. The results indicate that a moderate increase in the dietary S would not impair Se and copper status or cause related disorders in cattle. 41 refs., 2 figs., 2 tabs.

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

1987-04-01

 
 
 
 
341

Influence of the non-polar diluent (benzene) on the recoil collection of "1"2"8I charged species under (n,?) process in methyl iodide target  

International Nuclear Information System (INIS)

The collection of charged "1"2"8I recoil species produced in thermal neutron irradiated methyl iodide/benzene target on AgI/Ag electrodes showed low concentration on both the electrodes in presence of benzene than pure compound. Results are discussed on the basis of re-entry of recoil species as iodobenzene formation. (author)

1982-12-07

342

Proteomic analysis of differential protein expression in Acidithiobacillus ferrooxidans cultivated in high potassium concentration.  

Science.gov (United States)

Acidithiobacillus ferrooxidans is a chemolithoautotrophic acidophile that oxidizes ferrous iron or sulfur compounds to obtain energy in the presence of various ions. To investigate the potassium ion response of A. ferrooxidans, we conducted a proteomics analysis. We identified eight proteins that were differentially expressed in the presence of high potassium concentration, including four up-regulated and four down-regulated proteins. Transcription levels of the genes encoding differential expressed proteins were subsequently analyzed by Northern blot in the presence of high potassium concentration. Among the up-regulated proteins, GDP-mannose 4,6-dehydratase, ribose 5-phosphate isomerase A and ribose-phosphate pyrophosphokinase were known to be implicated in the synthesis of glycocalyx, suggesting that the formation of glycocalyx might be involved in the A. ferrooxidans response to high potassium concentration. Thickening of the glycocalyx layer was also observed in cells cultivated under high potassium concentration via transmission electronic microscopy (TEM) analysis. Among the down-regulated proteins, ATP synthase F1 delta subunit and ATP synthase F1 beta subunit were two important components of ATP synthase. ATP synthase (P-ATPase) is directly linked to the transport of potassium into the cell, thus Acidithiobacillus ferrooxidans might just reduce the quantity of ATP synthase to offset the high potassium level in the culture medium. Therefore, the results obtained here provide some new clues to improve our understanding of the response of A. ferrooxidans to high potassium concentration. PMID:23414699

Ouyang, Jianping; Guo, Wenbin; Li, Bo; Gu, Li; Zhang, Huijun; Chen, Xinhua

2013-08-25

343

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

Science.gov (United States)

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

Taudien, Jerker Y.; Kern, Ludwig A.

2013-09-01

344

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

International Nuclear Information System (INIS)

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

2012-02-01

345

Successful use of a modified MWD tool in a high-concentration LCM mud system  

Energy Technology Data Exchange (ETDEWEB)

This paper presents the successful field testing of a modified measurements while drilling (MWD) tool to handle high concentrations of lost circulation material (LCM) in the mud system. This specially formulated high concentration LCM mud system is commonly used to enable drilling through severely depleted and unconsolidated sandstone reservoirs without lost circulation. In this application the MWD tool is used to provide real time directional surveys, formation evaluation and drilling efficiency data. The original design of the MWD tool limited its use with this LCM mud system because of the tool`s high susceptibility to plugging. Research and development by the MWD company in cooperation with the Operator led to modifications of the MWD tool which now enables it to handle very high LCM concentrations without plugging, resulting in considerable cost savings to the Operator. The MWD company has also benefited by extending their tool`s application to a harsh LCM environment.

Attong, D.J.; Singh, U.B.

1995-03-01

346

Potassium 2-iodo­benzene­sulfonate monohydrate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the crystal structure of the title compound, K+·C6H4IO3S?·H2O, the potasium cation is 2.693?(3)–2.933?(3)?Å from the sulfonate and water O atoms (including symmetry-related atoms) and forms a two-dimensional sheet-like structure in the bc plane, with the iodo­benzene rings protruding above and below. The water mol­ecule of crystallization is hydrogen-bonded to sulfonate O atoms within this two-dimensional arrangement. Symmetry-related iodo­benzene rings are arranged perpend...

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

2008-01-01

347

Radium-226 concentration in spring water sampled in high radon regions  

Energy Technology Data Exchange (ETDEWEB)

Water {sup 226}Ra concentration in springs was measured in regions with high indoor radon: Ural, North Caucasus (Russia), Niska Banja (Serbia), Piestany (Slovakia), and Issyk-Kul (Kyrgyzstan). This paper presents the results for {sup 226}Ra concentration above 0.03 Bq l{sup -1}. Radium in water could indicate indoor radon problem in the region and water investigation is useful at the initial stage of radon survey. Even low {sup 226}Ra concentration in water (0.1-0.6 Bq l{sup -1}) caused high {sup 226}Ra activity in travertine (up to 1500 Bq kg{sup -1}), which resulted in indoor radon concentration above 2000 Bq m{sup -3} (Niska Banja)

Onishchenko, Aleksandra [Institute of Industrial Ecology UB RAS, S. Kovalevskoy St., 20A, 620219, Yekaterinburg (Russian Federation)], E-mail: onischenko@ecko.uran.ru; Zhukovsky, Michael [Institute of Industrial Ecology UB RAS, S. Kovalevskoy St., 20A, 620219, Yekaterinburg (Russian Federation); Veselinovic, Nenad; Zunic, Zora S. [VINCA Institute of Nuclear Sciences, ECE LAB, Mike Alasa St., 12-14, 11000, Belgrade (Serbia)

2010-04-15

348

Novel bioevaporation process for the zero-discharge treatment of highly concentrated organic wastewater.  

Science.gov (United States)

A novel process termed as bioevaporation was established to completely evaporate wastewater by metabolic heat released from the aerobic microbial degradation of the organic matters contained in the highly concentrated organic wastewater itself. By adding the glucose solution and ground food waste (FW) into the biodried sludge bed, the activity of the microorganisms in the biodried sludge was stimulated and the water in the glucose solution and FW was evaporated. As the biodegradable volatile solids (BVS) concentration in wastewater increased, more heat was produced and the water removal ratio increased. When the volatile solids (VS) concentrations of both glucose and ground FW were 120 g L(-1), 101.7% and 104.3% of the added water was removed, respectively, by completely consuming the glucose and FW BVS. Therefore, the complete removal of water and biodegradable organic contents was achieved simultaneously in the bioevaporation process, which accomplished zero-discharge treatment of highly concentrated organic wastewater. PMID:23886540

Yang, Benqin; Zhang, Lei; Lee, Yongwoo; Jahng, Deokjin

2013-10-01

349

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

1997-03-09

350

High Plasma 5-Hydroxyindole-3-Acetic Acid Concentrations in Subjects With Metabolic Syndrome  

Science.gov (United States)

OBJECTIVE Serotonin mediates vasoconstriction and induces the activation of platelets, which may promote atherosclerosis. The aim of this study was to investigate whether plasma 5-hydroxyindole-3-acetic acid (5-HIAA; a derivative end product of serotonin) concentrations are high in subjects with metabolic syndrome (MetS) and to investigate the relationship between plasma 5-HIAA concentrations and clinical and biochemical metabolic parameters. RESEARCH DESIGN AND METHODS Plasma 5-HIAA concentrations were measured in 311 subjects (152 men and 159 women) recruited from the Oike Clinic, which provides regular health check-ups for employees. We evaluated the relationship between plasma 5-HIAA concentrations and clinical and biochemical metabolic parameters, including waist circumference, serum lipid concentrations, fasting plasma glucose, or blood pressure. RESULTS Plasma 5-HIAA concentrations were higher in subjects with MetS than in those without, in both men (6.5 ± 4.4 vs. 4.9 ± 1.3 ng/mL, P < 0.005) and women (7.9 ± 6.5 vs. 5.2 ± 1.6 ng/mL, P < 0.005). In men, fasting plasma glucose (r = 0.197, P = 0.0146) was positively correlated, whereas HDL cholesterol (r = ?0.217, P = 0.0071) was negatively correlated, with logarithmic (log) (plasma 5-HIAA concentrations). In women, triglycerides (r = 0.252, P = 0.0013) and fasting plasma glucose (r = 0.344, P < 0.0001) were positively correlated, whereas HDL cholesterol (r = ?0.328, P < 0.0001) was negatively correlated, with log (5-HIAA concentrations). Furthermore, log (plasma 5-HIAA concentrations) were higher in subjects with more components of MetS. CONCLUSIONS Plasma 5-HIAA concentrations are high in subjects with MetS, suggesting the potential importance of serotonin in the development of cardiovascular disease in MetS.

Fukui, Michiaki; Tanaka, Muhei; Toda, Hitoshi; Asano, Mai; Yamazaki, Masahiro; Hasegawa, Goji; Imai, Saeko; Nakamura, Naoto

2012-01-01

351

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

352

Recurrent acute respiratory tract infections in areas with high nitrate concentrations in drinking water.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A review of the literature indicated an association among high nitrate ingestion, methemoglobinemia, and pathologic changes in bronchi and lung parenchyma. The present study examined a possible correlation among drinking water nitrate concentration, methemoglobin levels, cytochrome b(5) reductase activity, and acute respiratory tract infection with a history of recurrence (RRTI). Our study was conducted in five village units in the state of Rajasthan, India, with nitrate concentrations of 26,...

Gupta, S. K.; Gupta, R. C.; Gupta, A. B.; Seth, A. K.; Bassin, J. K.; Gupta, A.

2000-01-01

353

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

1987-01-01

354

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

355

Lead concentrations in lichens from the Canadian High Arctic in relation to the latitudinal pollution gradient  

International Nuclear Information System (INIS)

Measuring deposition of anthropogenic Pb is essential for quantifying global patterns of pollution dispersion. Concentrations of Pb, however, have only rarely been measured in lichens collected from the High Arctic. In this study the authors used flameless atomic absorption spectrophotometry to determine that the average Pb content in five lichen species from several remote sites on Ellesmere Island was 2?g g-1 dry wt. There are among the lowest Pb concentrations that have ever been recorded in Arctic plants. Literature data were combined to establish a latitudinal gradient showing decreasing Pb concentrations in lichens with increasing latitude throughout Canada. 35 refs., 1 fig., 2 tab

1996-08-01

356

Lead concentrations in lichens from the Canadian High Arctic in relation to the latitudinal pollution gradient  

Energy Technology Data Exchange (ETDEWEB)

Measuring deposition of anthropogenic Pb is essential for quantifying global patterns of pollution dispersion. Concentrations of Pb, however, have only rarely been measured in lichens collected from the High Arctic. In this study the authors used flameless atomic absorption spectrophotometry to determine that the average Pb content in five lichen species from several remote sites on Ellesmere Island was 2{mu}g g{sup -1} dry wt. There are among the lowest Pb concentrations that have ever been recorded in Arctic plants. Literature data were combined to establish a latitudinal gradient showing decreasing Pb concentrations in lichens with increasing latitude throughout Canada. 35 refs., 1 fig., 2 tab.

France, R.; Coquery, M. [McGill University, Montreal, PQ (Canada). Dept. of Biology

1996-08-01

357

High Voltage Solar Concentrator Experiment with Implications for Future Space Missions  

Science.gov (United States)

This paper describes the design, development, fabrication, and test of a high performance, high voltage solar concentrator array. This assembly is believed to be the first ever terrestrial triple-junction-cell solar array rated at over 1 kW. The concentrator provides over 200 W/square meter power output at a nominal 600 Vdc while operating under terrestrial sunlight. Space-quality materials and fabrication techniques were used for the array, and the 3005 meter elevation installation below the Tropic of Cancer allowed testing as close as possible to space deployment without an actual launch. The array includes two concentrator modules, each with a 3 square meter aperture area. Each concentrator module uses a linear Fresnel lens to focus sunlight onto a photovoltaic receiver that uses 240 series-connected triple-junction solar cells. Operation of the two receivers in series can provide 1200 Vdc which would be adequate for the 'direct drive' of some ion engines or microwave transmitters in space. Lens aperture width is 84 cm and the cell active width is 3.2 cm, corresponding to a geometric concentration ratio of 26X. The evaluation includes the concentrator modules, the solar cells, and the materials and techniques used to attach the solar cells to the receiver heat sink. For terrestrial applications, a finned aluminum extrusion was used for the heat sink for the solar cells, maintaining a low cell temperature so that solar cell efficiency remains high.

Mehdi, Ishaque S.; George, Patrick J.; O'Neill, Mark; Matson, Robert; Brockschmidt, Arthur

2004-01-01

358

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

359

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

360

Benzene exposure, glutathione S-transferase theta homozygous deletion, and sister chromatid exchanges.  

Science.gov (United States)

Recent studies have shown a strong positive correlation between chromosomal aberrations and future cancer risk. Sister chromatid exchange (SCE) has been widely applied in monitoring early biological effects to assess human genetic risk of cancer at the population level. We studied 45 Chinese workers (23 in the painting workshop of a glass factory with occupational exposure to benzene, and 22 fitters and planers in the punching and planing machine workshops of a nearby shipyard without such an exposure) to examine the association between occupational exposure to benzene and SCE frequency in peripheral blood lymphocytes. We also sought to investigate whether the glutathione S-transferase class theta gene (GSTT1) affects individual susceptibility to cytogenetic damage induced by in vivo exposure to benzene or in vitro exposure to diepoxybutane. The time-weighted average concentrations of benzene were 0.71 ppm in the exposed group and 0.03 ppm in the non-exposed group. Controlling for age, gender and educational level, cigarette smoking was significantly associated with increased SCE frequencies (P < 0.05), while GSTT1 genotype was significantly associated with DEB-induced SCEs (P < 0.01). There was no relationship between benzene exposure and baseline or DEB-induced SCEs. After stratification by smoking status, the GSTT1 deletion was a significant predictor of DEB-induced SCEs for both smokers (P < 0.05) and nonsmokers (P < 0.01). A significant benzene-GSTT1 interaction was found in nonsmokers (P < 0.05). Our study suggests that GSTT1 is an important determinant of heterogeneity in individual susceptibility to chromosomal damage associated with exposure to benzene. PMID:9438048

Xu, X; Wiencke, J K; Niu, T; Wang, M; Watanabe, H; Kelsey, K T; Christiani, D C

1998-02-01

 
 
 
 
361

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2005-06-01

362

090320 benzene supplementary note final  

…(2009) 5) Toxicological reports and Soil Guideline Value briefings The CLEA Guidance can help suitably qualified assessors to estimate the risk that a child or adult may be exposed to a soil concentration on a given site over a long period of exposure that may be a cause for concern to human health. The…

363

Synthesis of dodecyl lauroyl benzene sulfonate and its application in enhanced oil recovery  

Energy Technology Data Exchange (ETDEWEB)

A new hydrophobic surfactant, dodecyl lauroyl benzene sulfonate (DLBS), was synthesized and its application in enhanced oil recovery by alkali-surfactant-polymer (ASP) flooding was studied. The results show that DLBS can be synthesized by reaction of industrial dodecyl benzene with lauroyl chloride in the presence of AlCl{sub 3}, followed by sulfonation with ClSO{sub 3}H and neutralization with NaOH. The lauroyl-group is confirmed to be connected to the para-position of the alkylbenzene by1HNMR spectrum. The synthesized DLBS is well soluble in pure water and reservoir (connate) water at 45 C. It is highly surface active which is indicated by its low CMC of 1.1 . 10{sup -5} mol/L, and its low surface tension, {gamma}{sub cmc} of 28.6 mN m{sup -1}. By mixing with heavy alkylbenzene sulfonates of relatively low average molar mass (387g mol{sup -1}) at a total surfactant concentration of 5 mM, DLBS can reduce the interfacial tension of Daqing crude oil/connate water to an order of 10{sup -3} mN/m at 45 C in the presence of 0.5-1.0 wt.% NaOH and 1000 mg L{sup -1} of polymer. If the NaOH was replaced by a gentle alkaline salt, Na{sub 2}CO{sub 3}, certain amounts of dodecyl dimethyl carboxy betaine were added and the concentration of Na{sub 2}CO{sub 3} was increased to 1.2-2.0 wt.%, the interfacial tension of Daqing crude oil/connate water can also be reduced to an ultralow value. Therefore DLBS is a good hydrophobic surfactant applicable in ASP flooding with either NaOH or Na{sub 2}CO{sub 3} as alkaline agents. (orig.)

Cui, Zhenggang; Wu, Le; Sun, Mingming; Jiang, Jian-zhong; Wang, Feng [Jiangnan Univ., Wuxi (China). School of Chemical and Material Engineering

2011-09-15

364

Advancements in the Monitoring of Highly Concentrated Slurry Systems With Optical Low Coherence Reflectometry  

Energy Technology Data Exchange (ETDEWEB)

Optical Low Coherence Reflectometry (OLCR) is a non-destructive optical technique that can be used to measure 180{sup o} coherent backscatter of light incident on a heterogeneous medium. Changes in particle size and concentration may be extracted from the OLCR decay profiles of highly concentrated slurries and emulsions, such as high-level waste. We have shown OLCR to be a valuable tool for monitoring changes in particle size over several orders of magnitude at high concentration. We have made significant progress in the analysis of signals obtained from multiscattering events. We have observed the appearance of Mie resonances, a nonmonotonic oscillation of backscattered intensity dependent on optical parameters, over the interval where radii are comparable to the wavelength. Fundamental science development performed on model systems is essential for the analysis of polydispersity and the complex effects of clustering, sedimentation, gelation and other dynamic changes which may occur in an environmental waste system.

Randall, Summer Lockerbie; Brodsky, Anatol M.; Burgess, Lloyd W.

2004-03-31

365

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

366

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 ...

367

Carcinogenic properties of nitrosodimethylamine when combined with benzene, cadmium, boron or ethanol  

Energy Technology Data Exchange (ETDEWEB)

A combination of benzene (5.0 mg/l) or cadmium (0.01 mg/l) with nitrosodimethylamine (drinking water, 9 months) produced a significantly higher tumor incidence in female CBA X C57B1/6 mouse hybrids. The said agents are capable of modifying the carcinogenicity of other substances when present in water in concentrations exceeding the permissible one.

Litvinov, N.N.; Voronin, V.M.; Kazachkov, V.I.

1986-01-01

368

Solubilization of phenol and benzene in cationic micelles: Binding sites and effect on structure  

Energy Technology Data Exchange (ETDEWEB)

The effect of phenol and benzene additives on micellar structure in aqueous solutions of dodecyltrimethylammonium bromide has been studied by means of various experimental measurements. The solution properties studied include additive solubilities, tracer diffusion coefficients, electrical conductivity, viscosity, and ultraviolet absorbance. From the trace diffusion measurements the degree of partitioning of phenol into the micelles was calculated as a function of phenol concentration. A procedure for determining surfactant aggregation number and micelle concentration in ionic surfactant systems by means of diffusion and electrical conductivity data is presented. The solubilization of phenol and benzene in this system causes the micelles to swell, and it was observed that phenol addition leads to a greater increase in the size of aggregates than addition of benzene. Ultraviolet absorbance measurements revealed that the site of solubilization within the micelles is different for the two additives: Benzene solubilizes in the central core, while at low concentrations phenol is taken up in the outer palisade layer. However, the site of phenol solubilization, the shape of the micelles, and the physical properties of DTAB/phenol solutions change at a concentration of 1 mol of phenol solubilizate per mole of surfactant. Due to the saturation of the palisade layer with surfactant and additive molecules, phenol added to the DTAB system beyond this transition point most likely binds to the exterior of the micelles.

Kandori, K.; McGreevy, R.J.; Schechter, R.S. (Univ. of Texas, Austin (USA))

1989-02-23

369

Effects of prior acute exercise on circulating cytokine concentration responses to a high-fat meal.  

Science.gov (United States)

High-fat meal consumption alters the circulating cytokine profile and contributes to cardiometabolic diseases. A prior bout of exercise can ameliorate the triglyceride response to a high-fat meal, but the interactive effects of exercise and high-fat meals on cytokines that mediate cardiometabolic risk are not fully understood. We investigated the effects of prior exercise on the responses of circulating tumor necrosis factor-? (TNF-?), interleukin-6 (IL-6), IL-8, leptin, retinol-binding protein 4 (RBP4), vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), placental growth factor (PlGF), and soluble fms-like tyrosine kinase-1 (sFlt-1) to a high-fat meal. Ten healthy men were studied before and 4 h after ingestion of a high-fat meal either with or without ?50 min of endurance exercise at 70% of VO2 max on the preceding day. In response to the high-fat meal, lower leptin and higher VEGF, bFGF, IL-6, and IL-8 concentrations were evident (P high-fat meal on PlGF, TNF-?, or RBP4 concentrations. We found lower leptin concentrations with prior exercise (P high-fat meal on sFlt-1 (P high-fat meal increased IL-6 by 59% without prior exercise and 218% with prior exercise (P high-fat meal-induced changes in circulating cytokines, but does affect fasting or postprandial concentrations of IL-6, leptin, and sFlt-1. These data may reflect a salutary effect of prior exercise on metabolic responses to a high-fat meal. PMID:24303126

Brandauer, Josef; Landers-Ramos, Rian Q; Jenkins, Nathan T; Spangenburg, Espen E; Hagberg, James M; Prior, Steven J

2013-08-01

370

Survey of benzene and aromatics in Canadian Gasoline - 1994  

International Nuclear Information System (INIS)

A comprehensive database of the benzene and aromatics levels of gasoline produced in or imported into Canada during 1994, was presented. Environment Canada conducted a survey that requested refineries and importers to report quarterly on benzene and aromatics levels in gasoline. Benzene, which has been declared toxic by the Canadian Environmental Protection Act, is found in gasoline and is formed during the combustion of the aromatic components of gasoline. It was shown that benzene and aromatics levels differ regionally and seasonally. There are also variations in benzene levels between batches of gasoline produced at any one refinery. This report listed the responses to the benzene/aromatics survey. It also described the analytical procedures used to measure benzene and aromatics levels in gasoline, and provided guidelines for reporting gasoline benzene and total aromatics data. 7 tabs., 21 figs

1996-03-01

371

Occupational exposure to benzene at the ExxonMobil refinery in Beaumont, TX (1976-2007).  

Science.gov (United States)

Because crude oil and refined petroleum products can contain benzene and benzene is considered a known carcinogen by numerous independent and governmental agencies, including the International Agency for Cancer Research, the petroleum industry has implemented exposure control programs for decades. As part of the benzene control programs, significant exposure assessments have been performed; both qualitatively and through quantitative measurements. In this study, we evaluated the airborne concentrations of benzene and their variability over time at the ExxonMobil refinery in Beaumont, TX between 1976 and 2007. The results of 5854 personal air samples are included in this analysis; 3761 were considered non-task (> or =180 min) personal samples, and 2093 were considered task-related (<180 min) personal samples. Dock and loading rack samples were analyzed separately from the refinery samples because in addition to refinery products, employees at the dock and loading rack also handled chemical plant products. In general, the non-task personal refinery air samples indicated that exposures of the past 30 years were generally below the occupational exposure limit of 1 ppm (mean=0.30 ppm, SD=3.1), were higher during routine (mean=0.32 ppm, SD=3.3) than turnaround operations (mean=0.16 ppm, SD=0.87), and decreased slightly over time. The job sampled most frequently during routine operations was that of process technician, and, as broken down by area, resulted in the following mean benzene air concentrations: coker (n=146, mean=0.014 ppm, SD=0.036), lube extraction unit (n=31, mean<0.070 ppm), pipestills (n=136, mean=0.12, SD=0.47), waste treatment (n=107, mean=0.20, SD=0.28), and all other areas (n=1115, mean=0.059 ppm, SD=0.36). Task-based samples indicated that the highest exposures resulted from the tank cleaning tasks, although the overall task mean benzene air concentration was 1.4 ppm during routine operations. The most frequently sampled task during routine operations was blinding and breaking, and the mean benzene air concentrations associated with this task were statistically higher in the reformer area of the refinery (n=311, mean=3.2 ppm, SD=7.9) than in all other areas (n=200, mean=0.92 ppm, SD=3.1). However, task-related exposures were found to be statistically similar across job categories for a given task. This study thus provides a task-focused analysis for occupational exposure to benzene during refinery operations, and will be useful for understanding exposures at this refinery. PMID:20494616

Gaffney, Shannon H; Burns, Amanda M; Kreider, Marisa L; Unice, Ken M; Widner, Thomas E; Paustenbach, Dennis J; Booher, Lindsay E; Gelatt, Richard H; Panko, Julie M

2010-07-01

372

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)

1982-01-01

373

Development of xylose-fermenting yeasts for ethanol production at high acetic acid concentrations  

Energy Technology Data Exchange (ETDEWEB)

Mutants resistant to comparatively high levels of acetic acid were isolated from the xylose-fermenting yeasts Candida shehatae and Pichia Stipitis by adapting these cultures to increasing concentrations of acetic acid grown in shake-flask cultures. These mutants were tested for their ability to ferment xylose in presence of high acetic acid concentrations, in acid hydrolysates of wood, and in hardwood spent sulfite liquor, and compared with their wild-type counterparts and between themselves. The P. stipitis mutant exhibited faster fermentation times, better tolerance to acid hydrolysates, and tolerance to lower pH.

Mohandas, D.V.; Whelan, D.R.; Panchal, C.J. [Vetrogen Corporation, London, Ontario (Canada)

1995-12-31

374

Effectiveness and hazards of case finding for a high cholesterol concentration.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

OBJECTIVE--To see whether adults with high blood cholesterol concentrations (greater than 6.5 mmol/l) detected by case finding return to their doctor, receive appropriate advice, and report changes in their diet and whether adults found not to have high cholesterol concentrations on case finding are discouraged from changing their diet. DESIGN--Follow up study. SETTING--Seven general practices in the lower Hunter region of Australia. PARTICIPANTS--600 Men and women aged 25-65 who had their bl...

Kinlay, S.; Heller, R. F.

1990-01-01

375

Investigating high concentrations of three greenhouse gases in the Los Angeles Basin and San Bernardino Valley  

Science.gov (United States)

Following the Montreal Protocol of 1987 calling for the phase-out of CFCs and other ozone depleting substances, HCFCs and HFCs were introduced as alternatives despite still being greenhouse gases with high global warming potentials. In this study, whole air samples were collected during four research flights over Southern California aboard the NASA DC-8 Airborne Science Laboratory as part of the NASA Student Airborne Science Program. These samples were then analyzed by gas chromatography using a suite of detectors for many compounds, including HFC-134a, HCFC-22, and HFC-152a. HCFC-22 is primarily used as a refrigerant, while HFC-134a and HFC-152a are also used as aerosol propellants and foam blowing agents. High concentrations of these three compounds were observed for samples taken at low altitudes over urban areas around Los Angeles and San Bernardino. Exceptionally high concentrations were seen for all three compounds in samples taken near the Ontario and San Bernardino airports. Concentrations of HFC-134a, HCFC-22, and HFC-152a were enhanced above background levels near other airports sampled in the Los Angeles Basin and San Bernardino Valley. It is clear that concentrations of these three gases are higher in the San Bernardino Valley than in the Los Angeles Basin, and locations with exceptionally high concentrations were investigated to identify potential point sources. Concentrations of these three compounds were also compared to data from past SARP missions and data collected at Trinidad Head, California since 2005 as part of the AGAGE network. Comparison of the average values for each of these campaigns reveal that the background concentrations of HFC-134a, HCFC-22, and HFC-152a are all increasing with a strong linear trend in Southern California.

Kirpes, R.; Blake, D. R.; Marrero, J.

2013-12-01

376

2-Methyl-5-nitro-benzene-sulfonamide  

Science.gov (United States)

In the title compound, C7H8N2O4S, the nitro group is twisted by 9.61?(2)° relative to the benzene ring. In the crystal, mol­ecules are linked by N—H?O and N—H?(O,O) hydrogen bonds between the amino and sulfonyl groups, forming layers parallel to (001).

Zia-ur-Rehman, Muhammad; Khan, Islam Ullah; Naz, Nargis; Arshad, Muhammad Nadeem

2010-01-01

377

2-Methyl-5-nitro­benzene­sulfonamide  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In the title compound, C7H8N2O4S, the nitro group is twisted by 9.61?(2)° relative to the benzene ring. In the crystal, mol­ecules are linked by N—H?O and N—H?(O,O) hydrogen bonds between the amino and sulfonyl groups, forming layers parallel to (001).

Zia-ur-rehman, Muhammad; Khan, Islam Ullah; Naz, Nargis; Arshad, Muhammad Nadeem

2009-01-01

378

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...879 3. Vapor Density (air=1): 2...ventilated and good work practices...first signs. Bone marrow may appear...the physician has good reason to believe...allergies and some drugs may raise the...detection in the bone marrow of what are...to benzene are best taken so...

2010-07-01

379

Ebara ultra-high concentration clean ozonizer; Ebara chokonodo clean ozonizer  

Energy Technology Data Exchange (ETDEWEB)

Described herein is a newly developed clean ozonizer series OZC, generating ultrahigh concentrations of ozone gas for cleaning semiconductor production lines. The ozonizer is equipped with a discharge assembly, partly converting oxygen gas into ozone in a discharge space to which a high-frequency, high voltage is applied. The discharge assembly comprises a trenched electrode of pure aluminum coated with high-purity alumina, dielectric of sapphire substrate, and high-voltage electrode. A high voltage between the high-voltage and trenched electrode partly converts oxygen into ozone. These electrodes are cooled with water to produce ultrahigh-purity clean ozone gas free of impurities. The ozonizer stably generates an ozone gas containing ozone at a high concentration of above 10vol.% at a high oxygen flow rate of 20 to 45L/min. A still higher ozone concentration, above 13vol.%, can be stably generated by decreasing oxygen flow rate. The safety and protective devices for the ozonizer include detectors for ozone gas leakage, leaked and condensed water, and other emergency situations, e.g., abnormal gas pressure, cooling water and other ozonizer conditions. The ozonizer automatically stops discharging, when an emergency situation is detected and displayed. 8 figs., 2 tabs.

Harada, M.; Nishioka, Y.; Shinjo, R. [Ebara Corp., Tokyo (Japan)

1998-10-20

380

Significance of trophic transfer in predicting the high concentration of zinc in barnacles  

Energy Technology Data Exchange (ETDEWEB)

Barnacles are known to accumulate Zn to a phenomenal concentration, but physiological processes governing Zn accumulation are poorly defined. The authors determined the assimilation efficiency and efflux rate constant of Zn in barnacles (Balanus amphitrite) using radiotracer technique. Assimilation efficiency of Zn from ingested food ranged between 76 and 87% for the diatom diets and between 86 and 98% for the zooplankton preys. These AEs were the highest measured among aquatic invertebrates. Varying distribution in the soft tissues of zooplankton did not account for the variability of Zn AE observed among different zooplankton preys. Most Zn was distributed in the guts of the animals, presumably associated with the numerous granules beneath the gut epithelium. The efflux rate constant was 0.003 d{sup {minus}1}, and the calculated biological retention half-time was about 230 days. Using a simple bioenergetic-based kinetic model, the authors demonstrated that trophic transfer can account for such a high Zn concentration in barnacles. The predicted Zn concentrations in barnacles were directly comparable to the concentrations measured in Hong Kong coastal waters {micro}g. The high Zn concentration is related to its very efficient assimilation in barnacles coupled with a very low efflux rate. Biological variability must be fully appreciated before barnacles can be designated as an appropriate biomonitor of Zn contamination in coastal waters. The authors study suggests that metal concentration in aquatic animals can be predicted only when both physiological and geochemical processes are considered.

Wang, W.X.; Qui, J.W.; Qian, P.Y. [Hong Kong Univ. of Science and Technology (Hong Kong). Dept. of Biology

1999-09-01

 
 
 
 
381

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

Science.gov (United States)

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

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

2010-11-01

382

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

383

Adsorption selectivity of benzene and propene mixtures for various zeolites  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The nine-site benzene model of Zhao et al. (J. Phys. Chem. B 2005, 109, 5368-5374) has been used to systematically study the adsorption of benzene, propene, and benzene-propene mixtures in zeolites mordenite, Y, ?, silicalite, and MCM22. Interaction parameters for the benzene-zeolite interactions have been fitted to available adsorption experiments from literature. As an independent check of our force field, we have performed additional adsorption experiments using the TEOM technique and exc...

Ban, S.; Laak, A. N. C.; Jongh, P. E.; Eerden, J. P. J. M.; Vlugt, T. J. H.

2007-01-01

384

Risk assessment of leukaemia and occupational exposure to benzene.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Experimental toxicological studies have offered clear evidence that benzene induces haematopoietic neoplasms, and it is generally accepted that exposure to benzene is a risk factor for leukaemia, in particular for acute non-lymphatic leukaemia. Quantitative aspects of benzene risk assessment are still a matter of controversy, however. In several risk assessments an estimated 50 deaths from leukaemia per 1000 deaths would arise from exposures to benzene of 10 ppm during a working life of 30 ye...

Swaen, G. M.; Meijers, J. M.

1989-01-01

385