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1

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

Directory of Open Access Journals (Sweden)

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

Karimi Ali

2013-01-01

2

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

OpenAIRE

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

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

2013-01-01

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

4

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

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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

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

International Nuclear Information System (INIS)

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

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PREFRACTIONATION OF HIGH BENZENE PRECURSORS’ FEED FOR HYBRID REFORMER UNIT  

OpenAIRE

Benzene is toxic air pollutant and that’s why is set a constraint to 1% (v/v) in gasoline. Refiners have to lower benzene in its gasoline pool components. High benzene contributors are reformate and FCC gasoline. Worldwide practice is to optimize the reformate benzene content. Some light crude oils, like Samgori from Georgia contain more fraction with boiling temperature interval from 60 to 85oC. This fraction is an indicator for benzene precursors content in gasoline. There is a possibilit...

Kirilov, K.; Chomakov, M.; Stratiev, D.; Dinkov, R.

2008-01-01

8

PREFRACTIONATION OF HIGH BENZENE PRECURSORS’ FEED FOR HYBRID REFORMER UNIT  

Directory of Open Access Journals (Sweden)

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

K. Kirilov

2008-03-01

9

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

Science.gov (United States)

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 for a single weekday in 1995. The proportion of vehicles in "stop-go" mode, an 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 micrograms/m3, respectively) and from 16 school sites with moderate concentrations (means: 2.6, 32.2, and 5.7 micrograms/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 literature. PMID:12483801

Carr, David; von Ehrenstein, Ondine; Weiland, Stephan; Wagner, Claudia; Wellie, Oliver; Nicolai, Thomas; von Mutius, Erika

2002-10-01

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Ethyl benzene should be considered ototoxic at occupationally relevant exposure concentrations.  

Science.gov (United States)

Organic solvents can produce ototoxic effects in both man and experimental animals. The objective of this study was to review the literature on the effects of low-level exposure to ethyl benzene on the auditory system and consider its relevance for the occupational settings. Both human and animal investigations were evaluated only for realistic exposure concentrations based on the permissible exposure limits. In Quebec, the Time-Weighed Average Exposure Value for 8A h (TWAEV) is 100A ppm (434A mg/m(3)) and the Short-Term Exposure Value for 15A min (STEV) is 125A ppm (543A mg/m(3)). In humans, the upper limit for considering ototoxicity data relevant to the occupational exposure situation was set at STEV. Animal data were evaluated only for exposure concentrations up to 100 times the TWAEV. In workers, there is no evidence of either ethyl benzene-induced hearing losses or ototoxic interaction after combined exposure to ethyl benzene and noise. In rats, ethyl benzene affects the auditory function mainly in the cochlear mid-frequency range and ototoxic interaction was observed after combined exposure to noise and ethyl benzene. Further studies with sufficient data on the ethyl benzene exposure of workers are necessary to make a definitive conclusion. Given the current evidence from animal studies, we recommend considering ethyl benzene as an ototoxic agent. PMID:19022877

Vyskocil, A; Leroux, T; Truchon, G; Lemay, F; Gendron, M; Gagnon, F; El Majidi, N; Viau, C

2008-05-01

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

International Nuclear Information System (INIS)

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

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

13

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

International Nuclear Information System (INIS)

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

14

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

Science.gov (United States)

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

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

2014-12-01

15

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)

16

Amorphous carbon coatings prepared by high rate rf plasma deposition from fluorinated benzenes  

Science.gov (United States)

Amorphous carbon films were prepared by radio frequency plasma deposition from benzene and fluorinated benzenes: C6H6-mFm with m=0-6. The films have been characterized spectroscopically. The infrared spectrum shows that besides hydrogen, fluorine is incorporated in the films. With increasing m the concentration of fluorine in the film increases while the amount of chemically bonded hydrogen decreases and vanishes for m>3. The properties of these hydrogenated fluorinated amorphous carbon films (a-C:H,F) are qualitatively similar to those of hard carbon coatings (a-C:H) prepared from benzene. However, the deposition rate has been found to rise significantly (up to 900 nm min-1) with increasing fluorine content, m, in the substituted benzene. Optical data and protective properties of the films are reported.

Sah, R. E.; Dischler, B.; Bubenzer, A.; Koidl, P.

1985-04-01

17

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

International Nuclear Information System (INIS)

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

18

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

19

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

20

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

21

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

International Nuclear Information System (INIS)

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

22

Thin solar concentrator with high concentration ratio  

Science.gov (United States)

Solar concentrators are often used in conjunction with III-V multi-junction solar cells for cost reduction and efficiency improvement purposes. High flux concentration ratio, high optical efficiency and high manufacture tolerance are the key features required for a successful solar concentrator design. This paper describes a novel solar concentrator that combines the concepts, and thus the advantages, of both the refractive type ad reflective type. The proposed concentrator design adopts the Etendue-cascading concept that allows the light beams from all the concentric annular entrance pupils to be collected and transferred to the solar cell with minimal loss. This concept enables the system to perform near its Etendue-Limit and have a high concentration ratio simultaneously. Thereby reducing the costs of solar cells and therefor achieves a better the per watts cost. The concentrator demonstrated has a thing aspect ratio of 0.19 with a zero back focal distance. The numerical aperture at the solar cell immersed inside the dielectric concentrator is as high as 1.33 achieving a unprecedented high optical concentration ratio design.

Lin, Jhe-Syuan; Liang, Chao-Wen

2013-09-01

23

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...to repeated or prolonged contact with the skin. High concentration...III. Signs and Symptoms Direct skin contact with benzene may cause erythema...be performed by portable direct reading instruments, real-time continuous...

2010-07-01

24

Benzene emitted from glowing charcoal.  

Science.gov (United States)

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

Olsson, Maria; Petersson, Göran

2003-03-01

25

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

Science.gov (United States)

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

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

2014-08-01

26

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

International Nuclear Information System (INIS)

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

27

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)

28

Highly concentrating Fresnel lenses.  

Science.gov (United States)

A new type of convex Fresnel lens is discussed capable of concentrating solar radiation very near the ultimate concentration limit. 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 with that of a flat Fresnel lens, showing that the new lens is preferable for concentrating solar radiation. PMID:20212729

Kritchman, E M; Friesem, A A; Yekutieli, G

1979-08-01

29

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

Science.gov (United States)

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

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

2014-01-01

30

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.)

31

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

Science.gov (United States)

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

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

2014-12-15

32

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

Energy Technology Data Exchange (ETDEWEB)

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

Gonzalez Vanderhaghen, D.E

1998-12-31

33

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

OpenAIRE

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

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

1994-01-01

34

High concentration linear Fresnel reflectors  

International Nuclear Information System (INIS)

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

35

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

Science.gov (United States)

Benzene exposure of chemical workers was studied, during the entire workshift, by continuous monitoring of workplace benzene concentration, and 16 hours after the end of the workshift by the measurement of alveolar and blood benzene concentrations and excretion of urinary phenol. Exposure of hospital staff was studied by measuring benzene concentrations in the alveolar and blood samples collected during the hospital workshift. Instantaneous environmental air samples were also collected, at the moment of the biological sampling, for all the subjects tested. A group of 34 chemical workers showed an eight hour exposure to benzene, as a geometric mean, of 1.12 micrograms/l which corresponded, 16 hours after the end of the workshift, to a geometric mean benzene concentration of 70 ng/l in the alveolar air and 597 ng/l in the blood. Another group of 27 chemical workers (group A) turned out to be exposed to an indeterminable eight hour exposure to benzene that corresponded, the morning after, to a geometric mean benzene concentration of 28 ng/l in the alveolar air and 256 ng/l in the blood. The group of hospital staff (group B) had a benzene concentration of 14 ng/l in the alveolar air and 269 ng/l in the blood. Instantaneous environmental samples showed that in the infirmaries the geometric mean benzene concentration was 58 ng/l during the examination of the 34 chemical workers, 36 ng/l during the examination of the 27 chemical workers (group A), and 5 ng/l during the examination of the 19 subjects of the hospital staff (group B). Statistical analysis showed that the alveolar and blood benzene concentrations in the 34 workers exposed to 1.12 microgram/l of benzene differed significantly from those in groups A and B. It was found, moreover, that the alveolar and blood benzene concentrations were higher in the smokers in groups A and B but not in the smokers in the group of 34 chemical workers. The slope of the linear correlation between the alveolar and the instantaneous environmental benzene concentrations suggested a benzene alveolar retention of about 55%. Blood and alveolar benzene concentrations showed a highly significant correlation and the blood/air partition coefficient, obtained from the slope of the regression line, was 7.4. In the group of the 34 chemical workers no correlation was found between the TWA benzene exposure and the urinary phenol excretion. PMID:3378016

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

1988-01-01

36

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

37

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

Energy Technology Data Exchange (ETDEWEB)

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.

Dworjanyn, L.O.

1997-11-14

38

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

39

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

Science.gov (United States)

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

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

2010-02-01

40

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-07-01

41

X-ray Raman spectroscopic study of benzene at high pressure.  

Science.gov (United States)

We have used X-ray Raman spectroscopy (XRS) to study benzene up to approximately 20 GPa in a diamond anvil cell at ambient temperature. The experiments were performed at the High-Pressure Collaborative Access Team's 16 ID-D undulator beamline at the Advanced Photon Source. Scanned monochromatic X-rays near 10 keV were used to probe the carbon X-ray edge near 284 eV via inelastic scattering. The diamond cell axis was oriented perpendicular to the X-ray beam axis to prevent carbon signal contamination from the diamonds. Beryllium gaskets confined the sample because of their high transmission throughput in this geometry. Spectral alterations with pressure indicate bonding changes that occur with pressure because of phase changes (liquid: phase I, II, III, and III') and possibly due to changes in the hybridization of the bonds. Changes in the XRS spectra were especially evident in the data taken when the sample was in phase III', which may be related to a rate process observed in earlier shock wave studies. PMID:17880198

Pravica, Michael; Grubor-Urosevic, Ognjen; Hu, Michael; Chow, Paul; Yulga, Brian; Liermann, Peter

2007-10-11

42

Tuning the K+ concentration in the tunnel of OMS-2 nanorods leads to a significant enhancement of the catalytic activity for benzene oxidation.  

Science.gov (United States)

OMS-2 nanorods with tunable K(+) concentration were prepared by a facile hydrothermal redox reaction of MnSO4, (NH4)2S2O8, and (NH4)2SO4 at 120 °C by adding KNO3 at different KNO3/MnSO4 molar ratios. The OMS-2 nanorod catalysts are characterized by X-ray diffraction, transmission electron microscopy, N2 adsorption and desorption, inductively coupled plasma, and X-ray photoelectron spectrometry. The effect of K(+) concentration on the lattice oxygen activity of OMS-2 is theoretically and experimentally studied by density functional theory calculations and CO temperature-programmed reduction. The results show that increasing the K(+) concentration leads to a considerable enhancement of the lattice oxygen activity in OMS-2 nanorods. An enormous decrease (?T50 = 89 °C; ?T90 > 160 °C) in reaction temperatures T50 and T90 (corresponding to 50 and 90% benzene conversion, respectively) for benzene oxidation has been achieved by increasing the K(+) concentration in the K(+)-doped OMS-2 nanorods due to the considerable enhancement of the lattice oxygen activity. PMID:24180247

Hou, Jingtao; Liu, Liangliang; Li, Yuanzhi; Mao, Mingyang; Lv, Haiqin; Zhao, Xiujian

2013-12-01

43

High-concentration tritium sensor  

Energy Technology Data Exchange (ETDEWEB)

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

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

2004-01-01

44

Synthesis, bifunctionalization, and remarkable adsorption performance of benzene-bridged periodic mesoporous organosilicas functionalized with high loadings of carboxylic acids.  

Science.gov (United States)

Highly ordered benzene-bridged periodic mesoporous organosilicas (PMOs) that were functionalized with exceptionally high loadings of carboxylic acid groups (COOH), up to 80?mol?% based on silica, have been synthesized and their use as adsorbents for the adsorption of methylene blue (MB), a basic dye pollutant, and for the loading and release of doxorubicin (DOX), an anticancer drug, is demonstrated. These COOH-functionalized benzene-silicas were synthesized by the co-condensation of 1,4-bis(triethoxysilyl) benzene (BTEB) and carboxyethylsilanetriol sodium salt (CES), an organosilane that contained a carboxylic acid group, in the presence of non-ionic oligomeric surfactant Brij?76 in acidic medium. The materials thus obtained were characterized by a variety of techniques, including powder X-ray diffraction (XRD), nitrogen-adsorption/desorption isotherms, TEM, and (13)C and (29)Si solid-state NMR spectroscopy. Owing to the exceptionally high loadings of COOH groups, their high surface areas, and possible ?-?-stacking interactions, these adsorbents have very high adsorption capacities and extremely rapid adsorption rates for MB removal and for the controlled loading/release of DOX, thus manifesting their great potential for environmental and biomedical applications. PMID:23512281

Wu, Hao-Yiang; Shieh, Fa-Kuen; Kao, Hsien-Ming; Chen, Yi-Wen; Deka, Juti Rani; Liao, Shih-Hsiang; Wu, Kevin C-W

2013-05-10

45

Benzene clusters  

Science.gov (United States)

The infra-red photodissociation of benzene clusters has been studied in the frequency region 1020-1060 cm-1 using a CO2 laser. The infra-red absorption profiles have been measured by monitoring the depletion of signal intensity in a mass spectrometer as a function of laser wavelength for the ion clusters (C6H6)n+ for n = 2 - 10 and (C6H6)2+27. Comparing these results with infra-red data on the various states of benzene, leads to the proposal that the properties of small benzene clusters are best described in terms of a liquid-like rather than a solid-like state. Furthermore, it is suggested that the absorption profile linewidth, which is approximately constant throughout the cluster range investigated, is associated with vibrational dephasing.

Stace, A. J.; Bernard, D. M.; Crooks, J. J.; Reid, K. L.

46

High-resolution study of the difference band ?17 - ?20 of benzene  

International Nuclear Information System (INIS)

The difference band ?17 - ?20 of benzene centered at 779.643 cm-1 has been recorded on a high-resolution Fourier transform spectrometer with the aim of obtaining accurate information about the infrared- and Raman-inactive fundamental E2u mode ?20. Over 3,000 lines of the band have been measured with an effective resolution of ?0.0012 cm-1 and assigned to 70 subbands of the two components, ?-17 - ?-20 and ?+17 - ?+20, of this parallel E2g - E2u transition. Neither of the two states involved in the transition is perturbed by other vibrational states, but the levels of both ?17 and ?20 are affected by rather strong rotational l-type resonance and doubling. This effect has been explicitly taken into account in the analysis of the band. In adjusting the spectroscopic constants of the two states, the origin of the upper state ?17 and its constants ?C and C? were held at values obtained by Hollinger and Welsh from an analysis of a gas-phase Raman spectrum since they cannot be independently determined from a difference band. To break the correlations of the rotational constants ?B, q, ?J, and ?DJ between the two states, these parameters were also adjusted independently from the upper state combination differences R(J,K) - P(J,K) forences R(J,K) - P(J,K) for ?17 and from the lower state combination differences R(J - 1, K) - P(J + 1, K) for ?20. The spectroscopic constants obtained for the two states reproduce the observed line positions with an overall standard deviation of 0.00022 cm-1

47

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

Science.gov (United States)

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

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

2012-05-01

48

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

OpenAIRE

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

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

1988-01-01

49

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

Energy Technology Data Exchange (ETDEWEB)

Studies were completed in F344/N rats and B6C3F{sub 1} mice to determine the effect of dose, dose rate, route of administration, and rodent species on formation of total and individual benzene metabolites. Oral doses of 50 mg/kg or higher saturated the capacity for benzene metabolism in both rats and mice, resulting in an increased proportion of the administered dose being exhaled as benzene. The saturating air concentration for benzene metabolism during 6-hr exposures was between 130 and 900 ppm. At the highest exposure concentration, rats exhaled approximately half of the internal dose retained at the end of the 6-hr exposure as benzene; mice exhaled only 15% as benzene. Mice were able to convert more of the inhaled benzene to metabolites than were rats. In addition, mice metabolized more of the benzene by pathways leading to the putative toxic metabolites, benzoquinone and muconaldehyde, than did rats. In both rats and mice, the effect of increasing dose, administered orally or by inhalation, was to increase the proportion of the total metabolites that were the products of detoxification pathways relative to the products of pathways leading to putative toxic metabolites. This indicates low-affinity, high-capacity pathways for detoxification and high-affinity, low-capacity pathways leading to putative toxic metabolites. If the results of rodent studied performed at high doses were used to assess the health risk at low-dose exposures to benzene, the toxicity of benzene would be underestimated.

Henderson, R.F.; Sabourin, P.J.; Bechtold, W.E.; Griffith, W.C.; Medinsky, M.A. (Lovelace Biomedical and Environmental Research Institute, Albuquerque, NM (USA)); Birnbaum, L.S.; Lucier, G.W. (National Institute of Environmental Health Sciences, Research Triangle Park, NC (USA))

1989-07-01

50

High concentration aerosol removing device  

International Nuclear Information System (INIS)

Steams jetted out from a reactor pressure vessel upon occurrence of an accident are discharged from a vent tube to a suppression pool. Since the steams contain aerosols at high concentration, it is necessary to remove them. When the steams are discharged from the vent pipe into water, a great number of fine bubbles are formed and the aerosol particles are contained in each of the bubbles. The aerosol particles in the bubbles transfer into the water due to bubble cleaning effect by water in the suppression pool, that is, by a so called scrubbing effect. Since the scrubbing effect is enhanced more, as the bubbles are smaller and the bubble staying time in the water is longer, the diameter of holes is made smaller in a shallow place and it is made greater as the water depth is increased. Increase of the diameter for the holes in a deep place contributes to provide an effect of preventing clogging of the holes. In view of the above, radioactivity leak from the reactor container can surely prevented. (T.M.)

51

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

International Nuclear Information System (INIS)

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

52

High resolution infrared spectra of protonated benzene isolated in solid parahydrogen  

Science.gov (United States)

Identification of infrared (IR) spectra of protonated polyaromatic hydrocarbons (PAH) is important in understanding the unidentified IR bands of interstellar media. We demonstrate a new method that is superior to the Ar-tagging IR photodissociation or the IR-multiphoton-dissociation (IRMPD) methods currently used. The protonated benzene (C6H7^+) was produced on electron bombardment of a mixture of benzene (C6H6) and para-hydrogen (p-H2) during deposition. IR features of C6H7^+ and C6H7 were identified by observing the change in intensity upon photolysis and comparison with theoretical calculations. Lines of C6H7^+ decreased in intensity when the matrix was irradiated with light at 365 nm, those of C6H7 increased in intensity. Similar experiments were performed for a sample of C6D6/p-H2 and the production of C6D6H^+ was confirmed. Observed wavenumbers, relative IR intensities and deuterium isotopic shifts agree with those predicted for C6H7^+ and C6H7. Compared with previous methods, this method provides a wider spectral coverage with much narrower lines and more accurate relative IR intensities, and may be readily applied to larger protonated and neutral PAH.

Wu, Yu-Jong; Bahou, Momo; Lee, Yuan-Pern

2012-02-01

53

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

Science.gov (United States)

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

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

2014-08-15

54

Highly efficient electron-stimulated desorption of benzene from amorphous solid water ice  

Science.gov (United States)

The desorption of benzene (C6H6) from the surface of compact amorphous solid water (ASW) during irradiation with electrons in the range 100-350 eV has been investigated. Two desorption components, with particularly large cross-sections, were present in the observed desorption signal. The fast component, with a cross-section of >10-15cm2, is attributed to desorption of isolated C6H6 molecules that are ?-hydrogen bonded to small clusters of water (H2O) molecules on the compact ASW surface. The slower component, with a cross-section of ca. 10-16cm2, is attributed to a more complex desorption process involving larger C6H6 islands on the compact ASW surface. Possible desorption mechanisms are discussed.

Thrower, J. D.; Collings, M. P.; Rutten, F. J. M.; McCoustra, M. R. S.

2011-03-01

55

XR: a high-performance PV concentrator  

Science.gov (United States)

The performance of the XR solar concentrator, using a high efficiency multi-junction solar cell developed recently by Spectrolab, is presented. The XR concentrator is an ultra-compact Nonimaging optical design composed of a primary mirror and a secondary lens, which can perform close to the thermodynamic limit of concentration (maximum acceptance angle for a given geometrical concentration). The expected acceptance angle of the concentrator is about +/-2 deg for a geometrical concentration of 800x (a Fresnel lens and secondary system typically has +/-0.6 deg of acceptance for 300x of geometrical concentration). This concentrator is optimized to improve the irradiance distribution on the solar cell keeping it under the maximum values the cell can accept. The XR concentrator has high manufacturing tolerance to errors and can be produced using low cost manufacturing techniques. The XR is designed with the Simultaneous Multiple Surface (SMS) design method of Nonimaging Optics. Its application to high-concentration photovoltaics is now being developed in a consortium led by The Boeing Company, which has recently been awarded a project by the US DOE in the framework of the Solar America Initiative.

Hernández, M.; Benítez, P.; Miñano, J. C.; Cvetkovic, A.; Mohedano, R.; Dross, O.; Jones, R.; Whelan, D.; Kinsey, G. S.; Alvarez, R.

2007-09-01

56

Fluorescence Quenching at High Quencher Concentrations  

OpenAIRE

Chemical reactions occurring in dense media at high reactant concentrations can be described by rate ‘‘constants’’ which are actually functions of concentration. We present a theoretical model in which this so?called rate constant ‘‘renormalization’’ occurs for the specific case of fluorescence quenching in solution. We show that both the quenching and the excitation rate constants can become concentration dependent. We fit our theory to several sets of experimental data—o...

Peak, David; Werner, T. C.; Dennin Jr, R. M.; Baird, J. K.

1983-01-01

57

Highly concentrated foam formulation for blast mitigation  

Science.gov (United States)

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

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

2010-12-14

58

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

International Nuclear Information System (INIS)

Studies were completed in F344/N rats and B6C3F1 mice to determine the effect of dose, dose rate, route of administration, and rodent species on formation of total and individual benzene metabolites. Oral doses of 50 mg/kg or higher saturated the capacity for benzene metabolism in both rats and mice, resulting in an increased proportion of the administered dose being exhaled as benzene. The saturating air concentration for benzene metabolism during 6-hr exposures was between 130 and 900 ppm. At the highest exposure concentration, rats exhaled approximately half of the internal dose retained at the end of the 6-hr exposure as benzene; mice exhaled only 15% as benzene. Mice were able to convert more of the inhaled benzene to metabolites than were rats. In addition, mice metabolized more of the benzene by pathways leading to the putative toxic metabolites, benzoquinone and muconaldehyde, than did rats. In both rats and mice, the effect of increasing dose, administered orally or by inhalation, was to increase the proportion of the total metabolites that were the products of detoxification pathways relative to the products of pathways leading to putative toxic metabolites. This indicates low-affinity, high-capacity pathways for detoxification and high-affinity, low-capacity pathways leading to putative toxic metabolites. If the results of rodent studied performed at high doses were used to assess the health risk at low-dose exposures to benzene, the toxicity of ose exposures to benzene, the toxicity of benzene would be underestimated

59

Photovoltaic concentration at ultra-high flux  

Science.gov (United States)

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

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

2004-09-01

60

Benzene hexachloride poisoning in cattle.  

Science.gov (United States)

Of 174 cattle dipped in an emulsified preparation of benzene hexachloride labeled for plant use, 18 were fatally poisoned. The preparation contained 0.14% active ingredient, gamma isomer of benzene hexachloride (BHC), a normally safe concentration for cattle. Analyses revealed 0.08% gamma BHC in the used dip and 0.5, 7.9, and 198 ppm in liver, kidney, and hairskin specimens, respectively, from a fatally affected cow. Microscopic examination of the freshly prepared dip demonstrated emulsion droplets ranging from 5 to 60 mu in diameter. PMID:49345

Ray, A C; Norris, J D; Reagor, J C

1975-06-15

61

Facts about Benzene  

Science.gov (United States)

... used to make plastics, resins, and nylon and synthetic fibers. Benzene is also used to make some types of lubricants, rubbers, dyes, detergents, drugs, and pesticides. How you could be exposed to benzene Outdoor ...

62

Characterization of high concentration dust generator  

International Nuclear Information System (INIS)

This paper describes the development of fluidized bed type high concentration dust generator that keeps for long period dust concentration range of about 10 mg/m3 for the study of working place monitoring system and evaluation of respirator. The generator is keeping constant powder in fluidized bed for keeping the dust concentration. It is necessary to keep constant feeding rate of powder in order to keep the quantity of dust in the fluidized bed. Our generator enables to obtain constant feeding rate by a screw feeder and by using mixed powder with fluidising particles (glass beads) before feeding. The generator produces high concentration dust of 11.3 mg/m3 ± 1.0 mg/m3 for about 5 hours and keeps the dust size 4.2-4.6 ?m in mass median aerodynamic diameter with reasonable reproducibility. (author)

63

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

International Nuclear Information System (INIS)

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

64

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...of physical signs relating to blood disorders: (B) A complete blood count...concentrations, may result in various blood disorders, ranging from anemia to leukemia...irreversible, fatal disease. Many blood disorders associated with benzene...

2010-07-01

65

High-dimensional entanglement concentration of twisted photon pairs High-dimensional entanglement concentration  

Science.gov (United States)

Recently, Dada et al. reported on the experimental entanglement concentration and violation of generalized Bell inequalities with orbital angular momentum (OAM) [Nat. Phys. 7, 677 (2011)]. Here we demonstrate that the high-dimensional entanglement concentration can be performed in arbitrary OAM subspaces with selectivity. Instead of violating the generalized Bell inequalities, the working principle of present entanglement concentration is visualized by the biphoton OAM Klyshko picture, and its good performance is confirmed and quantified through the experimental Shannon dimensionalities after concentration.

Chen, L. X.; Wu, Q. P.

2012-10-01

66

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...may travel along the ground and be ignited by open...repeated or prolonged contact with the skin. High...Symptoms Direct skin contact with benzene may cause...Repeated or prolonged contact may result in drying...of benzene may have an initial stimulatory...

2010-07-01

67

The fate of benzene-oxide.  

Science.gov (United States)

Metabolism is a prerequisite for the development of benzene-mediated myelotoxicity. Benzene is initially metabolized via cytochromes P450 (primarily CYP2E1 in liver) to benzene-oxide, which subsequently gives rise to a number of secondary products. Benzene-oxide equilibrates spontaneously with the corresponding oxepine valence tautomer, which can ring open to yield a reactive alpha,beta-unsaturated aldehyde, trans-trans-muconaldehyde (MCA). Further reduction or oxidation of MCA gives rise to either 6-hydroxy-trans-trans-2,4-hexadienal or 6-hydroxy-trans-trans-2,4-hexadienoic acid. Both MCA and the hexadienal metabolite are myelotoxic in animal models. Alternatively, benzene-oxide can undergo conjugation with glutathione (GSH), resulting in the eventual formation and urinary excretion of S-phenylmercapturic acid. Benzene-oxide is also a substrate for epoxide hydrolase, which catalyzes the formation of benzene dihydrodiol, itself a substrate for dihydrodiol dehydrogenase, producing catechol. Finally, benzene-oxide spontaneously rearranges to phenol, which subsequently undergoes either conjugation (glucuronic acid or sulfate) or oxidation. The latter reaction, catalyzed by cytochromes P450, gives rise to hydroquinone (HQ) and 1,2,4-benzene triol. Co-administration of phenol and HQ reproduces the myelotoxic effects of benzene in animal models. The two diphenolic metabolites of benzene, catechol and HQ undergo further oxidation to the corresponding ortho-(1,2-), or para-(1,4-)benzoquinones (BQ), respectively. Trapping of 1,4-BQ with GSH gives rise to a variety of HQ-GSH conjugates, several of which are hematotoxic when administered to rats. Thus, benzene-oxide gives rise to a cascade of metabolites that exhibit biological reactivity, and that provide a plausible metabolic basis for benzene-mediated myelotoxicity. Benzene-oxide itself is remarkably stable, and certainly capable of translocating from its primary site of formation in the liver to the bone marrow. However, therein lies the challenge, for although there exists a plethora of information on the metabolism of benzene, and the fate of benzene-oxide, there is a paucity of data on the presence, concentration, and persistence of benzene metabolites in bone marrow. The major metabolites in bone marrow of mice exposed to 50 ppm [(3)H]benzene are muconic acid, and glucuronide and/or sulfate conjugates of phenol, HQ, and catechol. Studies with [(14)C/(13)C]benzene revealed the presence in bone marrow of protein adducts of benzene-oxide, 1,4-BQ, and 1,4-BQ, the relative abundance of which was both dose and species dependent. In particular, histones are bone marrow targets of [(14)C]benzene, although the identity of the reactive metabolite(s) giving rise to these adducts remain unknown. Finally, hematotoxic HQ-GSH conjugates are present in the bone marrow of rats receiving the HQ/phenol combination. In summary, although the fate of benzene-oxide is known in remarkable detail, coupling this information to the site, and mechanism of action, remains to be established. PMID:20036650

Monks, Terrence J; Butterworth, Michael; Lau, Serrine S

2010-03-19

68

Cellulase Inhibition by High Concentrations of Monosaccharides  

DEFF Research Database (Denmark)

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

Hsieh, Chia-Wen; Cannella, David

2014-01-01

69

DOE High Performance Concentrator PV Project  

Energy Technology Data Exchange (ETDEWEB)

Much in demand are next-generation photovoltaic (PV) technologies that can be used economically to make a large-scale impact on world electricity production. The U.S. Department of Energy (DOE) initiated the High-Performance Photovoltaic (HiPerf PV) Project to substantially increase the viability of PV for cost-competitive applications so that PV can contribute significantly to both our energy supply and environment. To accomplish such results, the National Center for Photovoltaics (NCPV) directs in-house and subcontracted research in high-performance polycrystalline thin-film and multijunction concentrator devices with the goal of enabling progress of high-efficiency technologies toward commercial-prototype products. We will describe the details of the subcontractor and in-house progress in exploring and accelerating pathways of III-V multijunction concentrator solar cells and systems toward their long-term goals. By 2020, we anticipate that this project will have demonstrated 33% system efficiency and a system price of $1.00/Wp for concentrator PV systems using III-V multijunction solar cells with efficiencies over 41%.

McConnell, R.; Symko-Davies, M.

2005-08-01

70

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

Science.gov (United States)

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

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

2012-04-16

71

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

72

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

73

Ammonia Solubility in High Concentration Salt Solutions  

International Nuclear Information System (INIS)

Solubility data for ammonia in water and various dilute solutions are abundant in the literature. However, there is a noticeable lack of ammonia solubility data for high salt, basic solutions of various mixtures of salts including those found in many of the Hanford Washington underground waste tanks. As a result, models based on solubility data for dilute salt solutions have been used to extrapolate to high salt solutions. These significant extrapolations need to be checked against actual laboratory data. Some indirect vapor measurements have been made. A more direct approach is to determine the ratio of solubility of ammonia in water to its solubility in high salt solutions. In various experiments, pairs of solutions, one of which is water and the other a high salt solution, are allowed to come to equilibrium with a common ammonia vapor pressure. The ratio of concentrations of ammonia in the two solutions is equal to the ratio of the respective ammonia solubilities (Henry's Law constants) at a given temperature. This information can then be used to refine the models that predict vapor space compositions of ammonia. Ammonia at Hanford is of concern because of its toxicity in the environment and its contribution to the flammability of vapor space gas mixtures in waste tanks

74

Ammonia Solubility in High Concentration Salt Solutions  

Energy Technology Data Exchange (ETDEWEB)

Solubility data for ammonia in water and various dilute solutions are abundant in the literature. However, there is a noticeable lack of ammonia solubility data for high salt, basic solutions of various mixtures of salts including those found in many of the Hanford Washington underground waste tanks. As a result, models based on solubility data for dilute salt solutions have been used to extrapolate to high salt solutions. These significant extrapolations need to be checked against actual laboratory data. Some indirect vapor measurements have been made. A more direct approach is to determine the ratio of solubility of ammonia in water to its solubility in high salt solutions. In various experiments, pairs of solutions, one of which is water and the other a high salt solution, are allowed to come to equilibrium with a common ammonia vapor pressure. The ratio of concentrations of ammonia in the two solutions is equal to the ratio of the respective ammonia solubilities (Henry's Law constants) at a given temperature. This information can then be used to refine the models that predict vapor space compositions of ammonia. Ammonia at Hanford is of concern because of its toxicity in the environment and its contribution to the flammability of vapor space gas mixtures in waste tanks.

HEDENGREN, D.C.

2000-02-01

75

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

OpenAIRE

Benzene exposure of chemical workers was studied, during the entire workshift, by continuous monitoring of workplace benzene concentration, and 16 hours after the end of the workshift by the measurement of alveolar and blood benzene concentrations and excretion of urinary phenol. Exposure of hospital staff was studied by measuring benzene concentrations in the alveolar and blood samples collected during the hospital workshift. Instantaneous environmental air samples were also collected, at th...

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

1988-01-01

76

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

International Nuclear Information System (INIS)

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

77

Benzene release. Status report  

International Nuclear Information System (INIS)

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

78

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

International Nuclear Information System (INIS)

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

79

Structures of Benzene Clusters  

Science.gov (United States)

The structures of small benzene clusters (C6H6)n (n=2-8) have been calculated using the discrete variational method (DVM) in the framework of local-density functional approximation (LDA) and molecular dynamics (MD) simulations. The structure of benzene dimer by our calculation is in good agreement with the Hartree-Fock studies. The structure of trimer is first optimized by MD with the intermolecular potential obtained from ab-initio study, and the intramolecule force field of Dreiding. Further calculations are carried out by DVM. We obtain the structure of benzene trimer from first principles calculation, and the optimized structure is a triangle having bloodstrain constructed from the T-type benzene dimer which is expected to be stable experimentally. The structures of tetramer to octamer molecules are obtained by MD and compared with previous calculations and experiments. Consistent structure patterns stemming from the fundamental T-shape dimer are found for all clusters.

Li, Zhiqiang; Ohno, Kaoru; Kawazoe, Yoshiyuki; Mikami, Masuhiro; Masuda, Yuji

80

High-efficiency concentrator silicon solar cells  

Energy Technology Data Exchange (ETDEWEB)

This report presents results from extensive process development in high-efficiency Si solar cells. An advanced design for a 1.56-cm{sup 2} cell with front grids achieved 26% efficiency at 90 suns. This is especially significant since this cell does not require a prismatic cover glass. New designs for simplified backside-contact solar cells were advanced from a status of near-nonfunctionality to demonstrated 21--22% for one-sun cells in sizes up to 37.5 cm{sup 2}. An efficiency of 26% was achieved for similar 0.64-cm{sup 2} concentrator cells at 150 suns. More fundamental work on dopant-diffused regions is also presented here. The recombination vs. various process and physical parameters was studied in detail for boron and phosphorous diffusions. Emitter-design studies based solidly upon these new data indicate the performance vs design parameters for a variety of the cases of most interest to solar cell designers. Extractions of p-type bandgap narrowing and the surface recombination for p- and n-type regions from these studies have a generality that extends beyond solar cells into basic device modeling. 68 refs., 50 figs.

Sinton, R.A.; Cuevas, A.; King, R.R.; Swanson, R.M. (Stanford Univ., CA (USA). Solid-State Electronics Lab.)

1990-11-01

81

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

International Nuclear Information System (INIS)

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

82

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

International Nuclear Information System (INIS)

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

83

High pressure fosters protein refolding from aggregates at high concentrations  

OpenAIRE

High hydrostatic pressures (1–2 kbar), combined with low, nondenaturing concentrations of guanidine hydrochloride (GdmHCl) foster disaggregation and refolding of denatured and aggregated human growth hormone and lysozyme, and ?-lactamase inclusion bodies. One hundred percent recovery of properly folded protein can be obtained by applying pressures of 2 kbar to suspensions containing aggregates of recombinant human growth hormone (up to 8.7 mg/ml) and 0.75 M GdmHCl. Covalently crosslinked, ...

St John, Richard J.; Carpenter, John F.; Randolph, Theodore W.

1999-01-01

84

Benzene Monitor System report  

International Nuclear Information System (INIS)

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

85

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

OpenAIRE

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 ...

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

2011-01-01

86

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

87

Survey the Efficiency of Catalytic Ozonation Process with Carbosieve in the Removal of Benzene from Polluted Air Stream  

Directory of Open Access Journals (Sweden)

Full Text Available Introduction & Objective: Benzene is one of the most common volatile organic compounds in the indoor and outdoor environments that has always been considered as one of the causes of air pollution. Thus before being discharged to the environment, it must be treated from pol-luted air stream. The aim of this study was to determine the efficiency of catalytic ozonation process with carbosieve in the removal of benzene from polluted air stream. Materials & Methods: The study was experimental in which catalytic ozonation process with carbosieve was used in the removal of benzene from polluted air stream. The experiments were carried out in a reactor with continuous system and the results of catalytic ozonation were compared with the results of single ozonation and carbosieve adsorbent .The sampling, benzene analyzing and determining of ozone concentration in samples were done with 1501 NMAM method by GC equipped with FID detector and iodometry , respectively. Results: The results of this study showed that the removal effectiveness of single ozonation process is averagely less than 19%. Also the efficiency of absorbent decreased with the con-centration increase of benzene.The increase ratio of efficiency in catalytic ozonation process to efficiency of carbosieve adsorbent was averagely 45%. Conclusion: With regard to high efficiency of catalytic ozonation process and increasing the benzene removal , the catalytic ozonation process is suggested as a promising and alternative technology for elimination of VOCs from the polluted air stream. (Sci J Hamadan Univ Med Sci 2014; 20 (4:303-311

M. Samarghandi

2014-01-01

88

Carrier concentration and high Tc superconductivity  

International Nuclear Information System (INIS)

A systematic study of the influence of oxygen depletion on the carrier concentration and the occurrence of superconductivity in a single-phase 1-2-3 Y-Ba-Cu-oxide material is presented. This is accomplished by successive measurements of the Hall and electrical resistivities, ac-susceptibility, and X-ray diffraction on the same sample, in which the oxygen deficiency is controlled and determined from thermogravimetry. With increasing oxygen depletion, the authors monitor how the 93 K orthorhombic superconductor, with an estimated carrier concentration of 0.6 x 10 to the 22nd carriers/cu cm at 100 K, is transformed into a tetragonal semiconductor with a very low carrier concentration. 8 references

89

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

90

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...the eosinophil count is less specific but also may be suspicious...and of alkaline phosphatase activity in peripheral granulocytes...and 5 drops of concentrated nitric acid. The benzene is converted...once, the percentage of the specific compound that is removed...

2010-07-01

91

Spectrophotometric determination of benzene in ethanol.  

Science.gov (United States)

A rapid, simple spectrophotometric method for the detection and determination of benzene in ethanol is described. Thus, using 1 cm cuvettes and applying the first and/or the second derivative methods, benzene can be determined in ethanol over the concentration range of 5-25 p.p.m. with a CV% less than 1% and with a detection limit of 2 p.p.m. This is considered to be an improvement over the method currently given in the British Pharmacopoeia. PMID:1856248

Barary, M H; Sabry, S M; Wahbi, A A

1991-04-01

92

Benzene in the blood and breath of normal people and occupationally exposed workers  

Energy Technology Data Exchange (ETDEWEB)

Benzene was measured in blood and alveolar air of 168 men, aged 20-58 years, subdivided into four groups: blood donors, hospital staff, chemical workers occupationally exposed to benzene, and chemical workers not occupationally exposed to benzene. The group of exposed workers was employed in work places with a mean environmental exposure to benzene of 1.62 mg/M3 (8 hr TWA). Non-exposed workers were employed elsewhere in the same plant, with an environmental exposure to benzene lower than 0.1 mg/M3. Blood and alveolar air samples were collected in the morning, before the start of the work shift for the chemical workers. The group of exposed workers was found to be significantly different from the other three groups, both for blood and alveolar benzene concentrations. The mean blood benzene concentration was 789 ng/l in the exposed workers, 307 ng/l in the non-exposed workers, 332 ng/l in the hospital staff, and 196 ng/l in the blood donors. Apart from the exposed workers, blood benzene concentration was significantly higher in smokers than in non-smokers. The mean alveolar benzene concentration was 92 ng/l in the exposed workers, 42 ng/l in the non-exposed workers, 22 ng/l in the hospital staff, and 11 ng/l in the blood donors. Alveolar benzene concentration was significantly higher in smokers than in non-smokers in the groups of the hospital staff and non-exposed workers, but not in the blood donors and exposed workers. In the three groups without occupational exposure considered altogether, the alveolar benzene concentration correlated significantly with environmental benzene concentration measured at the moment of the individual examinations, both in the smokers and non-smokers. In the same three groups and in the exposed workers, alveolar benzene concentration showed a significant correlation with the blood benzene concentration.

Brugnone, F.; Perbellini, L.; Faccini, G.B.; Pasini, F.; Danzi, B.; Maranelli, G.; Romeo, L.; Gobbi, M.; Zedde, A. (Universita di Verona (Italy))

1989-01-01

93

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

Directory of Open Access Journals (Sweden)

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

SB Mortazavi, A Sabzali, A Rezaee

2005-04-01

94

Pilot scale benzene stripping column testing: Review of test data and application to the ITP columns  

International Nuclear Information System (INIS)

Radioactive cesium will be removed from aqueous high level waste (HLW) solutions by precipitation with sodium tetraphenyl borate (TPB) in the In-Tank Precipitation (ITP) process. Benzene is generated due to the radiolysis of TPB, and dissolves into the decontaminated salt solution (DSS) and into the water used to wash (WW) the precipitate. These solutions will be processed through stripping columns to reduce the benzene concentration to satisfy limits for disposal of the DSS and for temporary storage of the WW. A pilot scale testing program to evaluate the stripping column operation in support of ITP startup activities has been completed. Equipment and test plans were developed so that data obtained from the pilot scale testing would be directly applicable to full scale column operation and could be used to project hydraulic performance and stripping efficiency of both columns. A review of the test data indicate that the ITP stripping columns will be capable of reducing benzene concentrations in salt solutions to satisfy Saltstone and Tank 22 acceptance limits. An antifoam (AF) will be required to maintain the column differential pressure below the vendor recommendation of 40 inches wc so that design feed rates can be achieved. Additionally, the testing program indicated that the nitrogen rate can be decreased from the ITP column design rates and still satisfy benzene concentration requirements in the product

95

High nitrogen concentration in Fe-Cr-Ni alloys  

Science.gov (United States)

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

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

1993-01-01

96

Refractive Secondary Solar Concentrator Demonstrated High-Temperature Operation  

Science.gov (United States)

Space applications that utilize solar thermal energy--such as electric power conversion systems, thermal propulsion systems, and furnaces--require highly efficient solar concentration systems. The NASA Glenn Research Center is developing the refractive secondary concentrator, which uses refraction and total internal reflection to efficiently concentrate and direct solar energy. When used in combination with advanced lightweight primary concentrators, such as inflatable thin films, the refractive secondary concentrator enables very high system concentration ratios and very high temperatures. Last year, Glenn successfully demonstrated a secondary concentrator throughput efficiency of 87 percent, with a projected efficiency of 93 percent using an antireflective coating. Building on this achievement, Glenn recently successfully demonstrated high-temperature operation of the secondary concentrator when it was used to heat a rhenium receiver to 2330 F. The high-temperature demonstration of the concentrator was conducted in Glenn's 68-ft long Tank 6 thermal vacuum facility equipped with a solar simulator. The facility has a rigid panel primary concentrator that was used to concentrate the light from the solar simulator onto the refractive secondary concentrator. NASA Marshall Space Flight Center provided a rhenium cavity, part of a solar thermal propulsion engine, to serve as the high-temperature receiver. The prototype refractive secondary concentrator, measuring 3.5 in. in diameter and 11.2 in. long, is made of single-crystal sapphire. A water-cooled splash shield absorbs spillage light outside of the 3.5-in. concentrator aperture. Multilayer foil insulation composed of tungsten, molybdenum, and niobium is used to minimize heat loss from the hightemperature receiver. A liquid-cooled canister calorimeter is used to measure the heat loss through the multilayer foil insulation.

Wong, Wayne A.

2002-01-01

97

Raman study of vibrational relaxation of cyclohexane in benzene solutions  

Science.gov (United States)

The Raman profiles of the ? 5 mode (802 cm -1) of cyclohexane, ? 5 (723 cm -1) of cyclohexane- d12 and ? 2 (992 cm -1) of benzene and its deuterated analogs have been measured as a function of concentration in the benzene—cyclohexane liquid system. The vibrational time correlation functions of cyclohexane in benzene solutions have been calculated by Fourier inversion of isotropic band contours. The concentration dependence of the experimental vibrational correlation times computed from the correlation functions and from the half width at half height have been compared with that predicted theoretically for various mechanisms of band broadening. We have tested the Fischer—Laubereau dephasing model and the Knapp—Fischer concentration-fluctuation model. We have found that the latter model reproduces well experimental data only for the ? 2 mode of benzene in solution.

Abramczyk, H.; Reimschüssel, W.

1984-01-01

98

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

99

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1993-08-01

100

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.nd 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)

101

High Performance Concentrating Photovoltaic Module Designs Employing Reflective Lens Optics  

Science.gov (United States)

The present study is aimed at advancing the optical component as well as optimizing the design of concentrating photovoltaic (CPV) modules in order to increase the conversion efficiency and improve the utility of CPV while obtaining the prescribed concentration ratio. In this work, we turn to non-traditional concentrating optics, namely Reflective Lenses™ (RL), first introduced in early 2000s. The optical configuration of RLs is unique since it combines the very low F/D number (hence resulting in a very low profile of the unit) of mirrors with a rear-focus of lenses and uses only a single-stage reflection. A liner-focus version of RLs, the Slat-Array Concentrator (SAC), is a capable alternative to the parabolic troughs for mid-concentration CPV. A point-focus version called the Ring-Array Concentrator (RAC) is deemed suitable for high concentration photovoltaics.

Vasylyev, Sergey V.; Vasylyev, Viktor P.

2011-12-01

102

Multijunction Photovoltaic Technologies for High-Performance Concentrators: Preprint  

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.

2006-05-01

103

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

OpenAIRE

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

Sb Mortazavi, A. Sabzali

2005-01-01

104

Occupational Exposure to Benzene and Changes in Hematological Parameters and Urinary Trans, Trans-Muconic Acid  

Directory of Open Access Journals (Sweden)

Full Text Available Background: For its toxicity, benzene exposure is one of the main health concerns for high risk occupations like gasoline station workers. However, there is little knowledge about the effect of benzene metabolites on hematological parameters.Objective: To evaluate the correlation between the urinary level of trans, trans-muconic acid (t, t-MA, a benzene metabolite, and some hematological parameters in gasoline workers.Methods: We studied 102 gasoline station workers from 11 gasoline stations in Pathumwan district, central area of Bangkok, Thailand. Their blood and urine samples were analyzed for some hematological parameters and urinary t, t-MA analysis by high performance liquid chromatography (HPLC.Results: We found an inverse correlation between urinary t, t-MA concentration and hemoglobin level (r = 0.281, p<0.05, hematocrit (r = 0.264, p<0.05. Those with higher urinary t, t-MA had a significantly (p<0.05 lower eosinophil counts than those with lower exposure. No significant correlation was found between urinary t, t-MA level and other white blood cell parameters and platelets count.Conclusion: Exposure to benzene would cause bone marrow depression presenting as drop in hemoglobin, hematocrit and eosinophil counts.

A Palasuwan

2013-01-01

105

Nonlinear diffusion in Acetone-Benzene Solution  

CERN Document Server

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

Obukhovsky, Vjacheslav V

2010-01-01

106

9-fold Fresnel-Köhler concentrator for increased uniform irradiance on high concentrations  

Science.gov (United States)

Non-uniform irradiance patterns created by Concentrated Photovoltaics (CPV) concentrators over Multi-Junction Cells (MJC) can originate significant power losses, especially when there are different spectral irradiance distributions over the different MJC junctions. This fact has an increased importance considering the recent advances in 4 and 5 junction cells. The spectral irradiance distributions are especially affected with thermal effects on Silicone-on-Glass (SoG) CPV systems. This work presents a new CPV optical design, the 9-fold Fresnel Köhler concentrator, prepared to overcome these effects at high concentrations while maintaining a large acceptance angle, paving the way for a future generation of high efficiency CPV systems of 4 and 5 junction cells.

Mendes-Lopes, João.; Benítez, Pablo; Zamora, Pablo; Miñano, Juan Carlos

2013-09-01

107

9-Fold Fresnel Köhler concentrator for increased uniform irradiance on high concentrations  

Science.gov (United States)

Non-uniform irradiance patterns created by Concentrated Photovoltaics (CPV) concentrators over Multi-Junction Cells (MJC) can originate significant power losses, especially when there are different spectral irradiance distributions over the different MJC junctions. This fact has an increased importance considering the recent advances in 4 and 5 junction cells. The spectral irradiance distributions are especially affected with thermal effects on Silicone-on-Glass (SoG) CPV systems. This work presents a new CPV optical design, the 9-fold Fresnel Köhler concentrator, prepared to overcome these effects at high concentrations while maintaining a large acceptance angle, paving the way for a future generation of high efficiency CPV systems of 4 and 5 junction cells.

Mendes-Lopes, João; Benítez, Pablo; Zamora, Pablo; Miñano, Carlos

2013-09-01

108

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. ? Reductisure 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.

109

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

110

BENZENE OXIDE PROTEIN ADDUCTS AS BIOMARKERS OF BENZENE EXPOSURE  

Science.gov (United States)

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

111

Case study of elevated layers of high sulfate concentration  

International Nuclear Information System (INIS)

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

112

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

International Nuclear Information System (INIS)

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

113

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

Energy Technology Data Exchange (ETDEWEB)

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

Steven B. Hawthorne

2007-04-15

114

Quantitative Characterization of Protein Associations in Highly Concentrated Solution  

Science.gov (United States)

With few exceptions, one cannot reliably predict the behavior of a protein at high concentration on the basis of knowledge obtained from experiments carried out at low concentration. Detection and quantitative characterization of protein-protein interactions in the high concentration regime (> 50 g/L) therefore presents both experimental and theoretical challenges to the investigator. Two experimental methods devised in our laboratory specifically for this purpose are described. (1) Non-ideal tracer sedimentation equilibrium. Instrumentation and theory for measuring and interpreting the equilibrium gradient of a labeled dilute tracer protein in a solution containing an arbitrary concentration of one or more unlabeled macromolecules are outlined. The composition dependence of the equilibrium gradient of several proteins, including ribonuclease at concentrations up to 200 g/L and immunoglobulin G at concentrations up to 125 g/L, will be presented and interpreted in the context of models taking into account both equilibrium self-association, and nonspecific repulsive steric or electrostatic repulsion. (2) Non-ideal light scattering. Recently developed instrumentation and theory for rapid measurement and interpretation of the light scattering of a protein solution over a broad range of concentration are outlined. The concentration-dependent light scattering of chymotrypsin A at three different pH values at concentrations up to 60 g/L, and the concentration-dependent light scattering of two monoclonal antibodies at concentrations up to over 200 g/L in solutions of varying ionic strength, are quantitatively accounted for by models that take into account both nonideal repulsion between protein molecules and specific modes of equilibrium self-association.

Minton, Allen

2010-03-01

115

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)

116

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)

117

Radon Measurements in Buildings with High Radon Concentrations  

International Nuclear Information System (INIS)

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

118

Development of hydrazine analyzer for high concentration of ethanolamine  

International Nuclear Information System (INIS)

A polarographic electrode method has been conventionally used for monitoring hydrazine concentrations in feedwater of pressurized water reactor (PWR) to control the secondary water chemistry. Measurements of hydrazine concentrations of the high pH controlled feedwater with ethanolamine (ETA) by this existing hydrazine analyzer were not stable on some occasions when the plant was in power operation. To solve this problem we developed a new hydrazine analyzer using p-dimethylaminobenzaldehyde (DABA) colorimetry and flow injection analysis (FIA) methods. (author)

119

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

120

Evaluation of radionuclide concentrations in high-level radioactive wastes  

International Nuclear Information System (INIS)

This report describes a possible approach for development of a numerical definition of the term ''high-level radioactive waste.'' Five wastes are identified which are recognized as being high-level wastes under current, non-numerical definitions. The constituents of these wastes are examined and the most hazardous component radionuclides are identified. This report suggests that other wastes with similar concentrations of these radionuclides could also be defined as high-level wastes. 15 refs., 9 figs., 4 tabs

121

Freeform solar concentrator with a highly asymmetric acceptance cone  

Science.gov (United States)

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

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

2014-10-01

122

The Interest and Potential of Ultra-High Concentration  

Science.gov (United States)

The benefits of the ultra-high concentration (>1,000 suns) are shown in terms of cost reduction, raw material availability and efficiency increase. The main challenges for the operation at such high concentrations, namely, (a) to keep a low series resistance; (b) to manufacture tunnel junctions with high peak currents and low series resistance; (c) to design and build advanced characterisation methods and tools; and (d) to increase the reliability of the devices are addressed and solutions for them are proposed. As examples of success in manufacturing multijunction solar cells at ultra-high concentration, we have developed and manufactured aGaInP/GaAs dual-junction device, which exhibits an efficiency of 32.6% for a concentration range going from 499 to 1,026 suns. This efficiency is the worldrecord efficiency for a dual-junction solar cell. Besides, the efficiency is still as high as 31% at 3,000 suns. We have extended this strategy tolattice-matched GaInP/Ga(In)As/Ge triple junction solar cells. At the current state of development, such cells show an efficiency of 36.2% at 700 suns. The theoretical optimisation shows that an efficiency well over 40% at 1,000 suns is achievable.

Algora, Carlos; Rey-Stolle, Ignacio

123

Materials balance for benzene: Level II. Final report  

Energy Technology Data Exchange (ETDEWEB)

A Level II materials balance was performed on benzene. Data are reported for benzene production from petroleum by four processes (catalytic reformation, toluene dealkylation, toluene disproportionation, and isolation from pyrolysis gasoline) for production from coal during coking. Amounts of benzene consumed for the synthesis of eight direct derivatives (ethylbenzene, cumene, cyclohexane, nitrobenzene, maleic anhydride, mono- and dichlorobenzene, alkylbenzenes, and biphenyl) and exports are presented. These uses constitute approximately 99 percent of total benzene usage. Nonconsumptive uses (solvents and pesticide component) are also tabulated. Releases due to each of the above processes are reported or estimated where possible using published and unpublished data. In addition, releases due to indirect production (refinery operation, coke oven operations, oil spills, non-ferrous metals manufacturing, ore mining, wood processing, coal mining, and two phases of the textile industry) are presented. Production of benzene as a component of gasoline and releases due to all phases of gasoline use are estimated. Locations of sites with high levels of benzene releases due to production and use are tabulated: the major 'hotspots' are Baton Rouge, Louisiana; Houston/Galveston, Texas; Midland, Michigan; and Puerto Rico. The uncertainty ranges of all numbers used or derived in this report are evaluated when possible and tabulated. Data gaps are evaluated and general recommendations are presented. The results of the report are summarized in two figures: the Environmental Flow Diagram for benzene in Appendix A, and the Materials Balance Flow Diagram in the Executive Summary.

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

1980-05-01

124

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

125

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

126

Absorption of lindane (gamma benzene hexachloride) in infants and children.  

Science.gov (United States)

Concentrations of lindane (gamma benzene hexachloride) were measured in blood from children who had received treatment with 1% lindane lotion. Lindane was present in the blood of all patients from two of 48 hours following application. Concentrations were inversely related to weight, surface area, and were independent of the quantity of lindane applied. PMID:72815

Ginsburg, C M; Lowry, W; Reisch, J S

1977-12-01

127

Development of microbial engineered whole-cell systems for environmental benzene determination.  

Science.gov (United States)

This paper reports the development of two recombinant bacterial systems that can be used to monitor environmental benzene contamination based on Escherichia coli, which carry genes coding for benzene dioxygenase and benzene dihydrodiol dehydrogenase from Pseudomonas putida MST. E. coli strains express these two enzymes under the control of the Ptac promoter or without any induction. These activities can be detected electrochemically or colorimetrically and used to monitor benzene pollution in environmental air samples collected from an oil refinery assessing benzene by different laboratory experimental procedures. The procedures involving whole-cell bioassays determine the concentration of benzene through benzene dioxygenase activity, which allows for direct correlation of oxygen consumption, and through the benzene dihydrodiol dehydrogenase that causes catechol accumulation and restores NADH necessary for the activity of the first enzyme. Oxygen consumption and catechol production deriving from both enzymatic activities are related to benzene concentration and their measurements determined the sensitivity of the system. The results indicated that the sensitivity was enough to detect the benzene vapor at a lower concentration level of 0.01 mM in about 30 min. The possibility for on-line monitoring of benzene concentration by our new recombinant cells results from the fact that no particular treatment of environmental samples is required. This is a major advantage over other biosensors or assays. Moreover, the development of microbial cells that did not require any addition or effectors for the transcription of the specific enzymes, allowed these systems to be more versatile in automated environmental benzene monitoring. PMID:20980054

Di Gennaro, P; Bruzzese, N; Anderlini, D; Aiossa, M; Papacchini, M; Campanella, L; Bestetti, G

2011-03-01

128

Process of radiation chlorination of benzene in the continuous flow system  

International Nuclear Information System (INIS)

The process of radiation chlorination of benzene was studied in the continuous flow system. The influence of the following parameters: the flow rate of benzene, irradiation dose, concentration of chlorine in benzene, temperature and the dose rate on the rate of reaction and the composition of the obtained product was determined. Comparative experiments with the solvents: dichloromethane and tetrachloroethane were also carried out. A possibility of the industrial application of the method is discussed. 6 refs., 2 figs., 2 tabs. (author)

129

Beryllium-10 concentrations in water samples of high northern latitudes  

Energy Technology Data Exchange (ETDEWEB)

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

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

1997-09-01

130

Decomposition of benzene in a corona discharge at atmospheric pressure  

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-05-01

131

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

132

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2013-06-01

133

Benzene-derived carbon nanothreads  

Science.gov (United States)

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

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

2015-01-01

134

Partial hydrogenation of benzene to cyclohexene  

Science.gov (United States)

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

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

1997-11-01

135

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

136

Unphysiologically high magnesium concentrations support chondrocyte proliferation and redifferentiation.  

Science.gov (United States)

The effect of unphysiologically high extracellular magnesium concentrations on chondrocytes, induced by the supplementation of magnesium sulfate, was studied using a 3-phase tissue engineering model. The experiments showed that chondrocyte proliferation and redifferentiation, on the gene and protein expression level, are enhanced. A negative influence was found during chondrogenesis where an inhibition of extracellular matrix formation was observed. In addition, a direct impact on chondrocyte metabolism, elevated magnesium concentrations also affected growth factor effectiveness by consecutive influences during chondrogenesis. All observations were dosage dependent. The results of this study indicate that magnesium may be a useful tool for cartilage tissue engineering. PMID:17518690

Feyerabend, Frank; Witte, Frank; Kammal, Michael; Willumeit, Regine

2006-12-01

137

High-flux characterization of ultrasmall multijunction concentrator solar cells  

Science.gov (United States)

A characterization study of ultrasmall ultraefficient multijunction concentrator solar cells is presented, with emphasis on performance sensitivity to light intensity and distribution. Information of this type is essential in the design and optimization of the latest generations of high-flux photovoltaic systems. Cell miniaturization allows increasing the concentration at which efficiency peaks, facilitates passive heat rejection, and permits the use of all-glass optics. However, few device measurements have been published on ultrasmall cells. Extensive measurements, up to ˜5000 suns, on the 1.0mm2 active region within the busbars are reported and analyzed.

Korech, Omer; Hirsch, Baruch; Katz, Eugene A.; Gordon, Jeffrey M.

2007-08-01

138

High-concentration photovoltaic designs based on miniature parabolic dishes  

Science.gov (United States)

A new approach for concentrating photovoltaic systems that can easily attain the maximum flux levels commensurate with solar cell technology is proposed. The collection unit is a miniature paraboloidal dish which concentrates sunlight into a short glass rod. The flux distribution of the transported light is homogenized in a miniature glass kaleidoscope that is optically coupled to a small high-efficiency solar cell. The cell resides behind the dish and can be cooled adequately with a passive heat sink. These nominally independent collection units can be assembled into modules and arrays that produce almost any prescribed power level. All system elements are predicated on existing technologies.

Feuermann, Daniel; Gordon, Jeffrey M.

2001-11-01

139

High concentrations of Vitamin C induce Oxidative Stress in Blood  

OpenAIRE

Vitamin C is water soluble, being a potent antioxidant in organisms and also having a per-oxidant effect. In this study, the bloods of healthy animals were incubated with different concentrations of vitamin C at 4C° for 24 hours. The lipid per-oxidation and protein damage were investigated. The sample incubation with high concentrations showed significant change in the level of lipid per-oxidation and protein carbonyl. These results supported that oxidative stress may play a role in the mech...

Sadighara, Parisa; Salar-amoli, Jamileh

2009-01-01

140

Substituent effect in benzene dication  

OpenAIRE

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

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

2014-01-01

141

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

International Nuclear Information System (INIS)

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

142

Benzene bioremediation using cow dung microflora in two phase partitioning bioreactor  

International Nuclear Information System (INIS)

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

143

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

144

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

Science.gov (United States)

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

Oren, Aharon

2013-01-01

145

Athletic Activity and Hormone Concentrations in High School Female Athletes.  

Science.gov (United States)

Context : ? Physical activity may affect the concentrations of circulating endogenous hormones in female athletes. Understanding the relationship between athletic and physical activity and circulating female hormone concentrations is critical. Objective : ? To test the hypotheses that (1) the estradiol-progesterone profile of high school adolescent girls participating in training, conditioning, and competition would differ from that of physically inactive, age-matched adolescent girls throughout a 3-month period; and (2) athletic training and conditioning would alter body composition (muscle, bone), leading to an increasingly greater lean-body-mass to fat-body-mass ratio with accompanying hormonal changes. Design : ? Cohort study. Settings : ? Laboratory and participants' homes. Patients or Other Participants : ? One-hundred-six adolescent girls, ages 14-18 years, who had experienced at least 3 menstrual cycles in their lifetime. Main Outcome Measure(s) : ? Participants were prospectively monitored throughout a 13-week period, with weekly physical-activity assessments and 15 urine samples for estrogen, luteinizing hormone, creatinine, and progesterone concentrations. Each girl underwent body-composition measurements before and after the study period. Results : ? Seventy-four of the 98 girls (76%) who completed the study classified themselves as athletes. Body mass index, body mass, and fat measures remained stable, and 17 teenagers had no complete menstrual cycle during the observation period. Mean concentrations of log(estrogen/creatinine) were slightly greater in nonathletes who had cycles of 35 days. Mean log(progesterone/creatinine) concentrations in nonathletes were less in the first half and greater in the second half of the cycle, but the differences were not statistically significant. Conclusions : ? A moderate level of athletic or physical activity did not influence urine concentrations of estrogen, progesterone, or luteinizing hormones. However, none of the participants achieved high levels of physical activity. A significant number (17%) of girls in both activity groups were amenorrheic during the 3-month study period. PMID:25329345

Wojtys, Edward M; Jannausch, Mary L; Kreinbrink, Jennifer L; Harlow, Siobán D; Sowers, MaryFran R

2014-10-20

146

Reactions of energetic carbon-11 with benzene leading to acetylene  

International Nuclear Information System (INIS)

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

147

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 isolatxpression 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

148

Nonfaradaic nanoporous electrochemistry for conductometry at high electrolyte concentration.  

Science.gov (United States)

Nanoporous electrified surfaces create a unique nonfaradaic electrochemical behavior that is sensitively influenced by pore size, morphology, ionic strength, and electric field modulation. Here, we report the contributions of ion concentration and applied ac frequency to the electrode impedance through an electrical double layer overlap and ion transport along the nanopores. Nanoporous Pt with uniform pore size and geometry (L2-ePt) responded more sensitively to conductivity changes in aqueous solutions than Pt black with poor uniformity despite similar real surface areas and enabled the previously difficult quantitative conductometry measurements at high electrolyte concentrations. The nanopores of L2-ePt were more effective in reducing the electrode impedance and exhibited superior linear responses to not only flat Pt but also Pt black, leading to successful conductometric detection in ion chromatography without ion suppressors and at high ionic strengths. PMID:25590534

Bae, Je Hyun; Kang, Chung Mu; Choi, Hyoungseon; Kim, Beom Jin; Jang, Woohyuk; Lim, Sung Yul; Kim, Hee Chan; Chung, Taek Dong

2015-02-17

149

Mitigation of high 222 Rn concentrations in potable water  

International Nuclear Information System (INIS)

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

150

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

151

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)

152

Lipid transfer between vesicles: effect of high vesicle concentration.  

OpenAIRE

The problem of the desorption of a lipid molecule from a lipid vesicle (donor) and its incorporation into another vesicle (acceptor) at high acceptor concentrations, which has been investigated experimentally (Jones, J. D. and Thompson, T. E., 1990. Biochemistry, 29:1593-1600), is analyzed here from a theoretical point of view, formulated in terms of the diffusion equation with appropriate boundary conditions. The goal is to determine whether or not the observed acceleration of the off-rate f...

Almeida, P. F.

1999-01-01

153

Destruction of benzene (VOC) using electron beam radiation in flue gas treatment  

International Nuclear Information System (INIS)

In this study, Benzene, one of the volatile organic compounds (VOCs) is used to destruct by electron beam. As we know Benzene is one of the most stable compound and very difficult to break. By using the powerful energy produced by electron beam, the benzene compound can be broken up to form new compounds. The technique used in this experiment is by using static process in a control condition where other gases are not allowed to enter the Tedlar bag or glass jar. The Tedlar Bag and Glass jar are used as media for benzene gas to be irradiated. From the experiment it was found that the Tedlag Bag is more suitable than the glass jar the electron beam can easily penetrate and destroy benzene gas. Nitrogen and Helium gas is used as a cleaning gas. The concentrations of benzene gas used for this study are 100 ppm. (part per million), 1 ppmv, and 1 ppmv each for 32 types of VOC. From the result it can be concluded that the electron beam technique used for destruction of benzene (VOQ is very suitable for the low concentration of benzene, the dose needed for the destruction to reach 85-95% is only between 8-12 kGy. It was also observed that many new compound can be produced when benzene is destruct by electron beam. (Author)

154

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

155

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)

156

Optical design considerations for high-concentration photovoltaics  

Science.gov (United States)

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

Garboushian, Vahan; Gordon, Robert

2006-08-01

157

Disposal of high-concentration hydrazine solutions by chemical decomposition  

International Nuclear Information System (INIS)

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

158

Potential metallurgical treatment of copper concentrates with high arsenic contents  

Scientific Electronic Library Online (English)

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

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

2011-06-01

159

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

CERN Document Server

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

160

Fabrication procedures for manufacturing high uranium concentration dispersion fuel elements  

International Nuclear Information System (INIS)

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

161

Spectroscopic properties of fluorophosphate glass with high Er3+ concentration  

Science.gov (United States)

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

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

2007-01-01

162

Novel inorganic nanomaterials generated with highly concentrated sunlight  

Science.gov (United States)

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

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

2008-08-01

163

S-phenylcysteine formation in hemoglobin as a biological exposure index to benzene  

Energy Technology Data Exchange (ETDEWEB)

In this paper, we describe the development of a gas chromatography/mass spectroscopy assay for quantitating the binding of the benzene metabolite, benzene oxide, to cysteine groups in hemoglobin. We used this assay to study the hemoglobin adduct, S-phenylcysteine (SPC), in the blood of rats and mice exposed to benzene either by inhalation or by gavage. We were able to detect SPC in the hemoglobin of exposed rats and mice, to show the linearity of the exposure dose-response relationship, and to establish the sensitivity limits of this assay. For the same exposure regime, rats showed considerably higher levels of SPC in the globin of humans occupationally exposed to benzene. We attempted to determine whether the SPC found in hemoglobin originated from the metabolism of benzene within or outside of the red blood cell. We hypothesized that the greatest red blood cell metabolism would be associated with peripheral reticulocytes, which retain high metabolic capacity. After exposing rats to benzene, we isolated the red blood cells and used discontinuous Percoll gradients to fractionate them into age groups. No differences in SPC levels were found among any of the fractions, suggesting that the SPC found in globin originates from the metabolism of benzene to benzene oxide in a location external to the red blood cell. To our knowledge, this is the first demonstration of the nonenzymatic binding of the benzene metabolite, benzene oxide, to protein. (orig./MG).

Bechthold, W.E.; Sun, J.D.; Henderson, R.F. (Inhalation Toxicology Research Inst., Lovelace Biomedical and Environmental Research Inst., Albuquerque, NM (United States)); Birnbaum, L.S. (Environmental Toxicology Div., Health Effects Research Lab., US Environmental Protection Agency, Research Triangle Park, NC (United States)); Yin, S.N.; Li, G.L. (Inst. of Occupational Medicine, Chinese Academy of Preventive Medicine, Beijing (China)); Lucier, G. (National Inst. of Environmental Health Sciences, Research Triangle Park, NC (United States)); Kasicki, S.

1992-05-01

164

Mapping Global Atmospheric CO2 Concentration at High Spatiotemporal Resolution  

Directory of Open Access Journals (Sweden)

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

Yingying Jing

2014-11-01

165

Recovery of uranium from solutions containing high concentration of fluoride  

International Nuclear Information System (INIS)

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

166

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

Science.gov (United States)

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

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

2014-10-01

167

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

International Nuclear Information System (INIS)

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

168

Degradative capacities and bioaugmentation potential of an anaerobic benzene-degrading bacterium strain DN11  

Energy Technology Data Exchange (ETDEWEB)

Azoarcus sp. strain DN11 is a denitrifying bacterium capable of benzene degradation under anaerobic conditions. The present study evaluated strain DN11 for its application to bioaugmentation of benzene-contaminated underground aquifers. Strain DN11 could grow on benzene, toluene, m-xylene, and benzoate as the sole carbon and energy sources under nitrate-reducing conditions, although o- and p-xylenes were transformed in the presence of toluene. Phenol was not utilized under anaerobic conditions. Kinetic analysis of anaerobic benzene degradation estimated its apparent affinity and inhibition constants to be 0.82 and 11 {mu}M, respectively. Benzene-contaminated groundwater taken from a former coal-distillation plant site in Aichi, Japan was anaerobically incubated in laboratory bottles and supplemented with either inorganic nutrients (nitrogen, phosphorus, and nitrate) alone, or the nutrients plus strain DN11, showing that benzene was significantly degraded only when DN11 was introduced. Denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene fragments, and quantitative PCR revealed that DN11 decreased after benzene was degraded. Following the decrease in DN11 16S rRNA gene fragments corresponding to bacteria related to Owenweeksia hongkongensis and Pelotomaculum isophthalicum, appeared as strong bands, suggesting possible metabolic interactions in anaerobic benzene degradation. Results suggest that DN11 is potentially useful for degrading benzene that contaminates underground aquifers at relatively low concentrations. 50 refs., 6 figs., 1 tab.

Yuki Kasai; Yumiko Kodama; Yoh Takahata; Toshihiro Hoaki; Kazuya Watanabe [Marine Biotechnology Institute, Kamaishi (Japan)

2007-09-15

169

Hydrogen concentration and distribution in high-purity germanium crystals  

International Nuclear Information System (INIS)

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

170

Do high concentrations of microcystin prevent Daphnia control of phytoplankton?  

Science.gov (United States)

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

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

2013-04-15

171

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

172

Air ion concentrations under overhead high-voltage transmission lines  

Science.gov (United States)

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

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

173

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...chemical analysis by gas chromatography. Sampling and...disulfide through 13x molecular sieve). 4.2. Benzene...760 mm 78.11=molecular weight of benzene...performance liquid chromatography (HPLC)....

2010-07-01

174

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...access to their employees, to a material safety data sheet (MSDS) which addresses benzene and complies with 29 CFR 1910.1200...CFR 1910.1200, that they deliver to downstream employers an MSDS which addresses benzene. (3) Information and...

2010-07-01

175

The Solubility of Phenylborate Compounds in Benzene  

International Nuclear Information System (INIS)

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

176

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...benzene immediately causes pulmonary edema and hemorrhage of pulmonary tissue. There is some...Symptoms and signs of benzene toxicity can be non-specific...are indicative of potential toxicity, particularly if all...

2010-07-01

177

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

178

Benzene in blood as a biomarker of low level occupational exposure.  

Science.gov (United States)

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 micrograms/m3. 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 micrograms/m3, no difference was found in blood benzene concentration in exposed and non-exposed subjects. PMID:10535123

Brugnone, F; Perbellini, L; Romeo, L; Cerpelloni, M; Bianchin, M; Tonello, A

1999-09-01

179

Source identification of high glyme concentrations in the Oder River.  

Science.gov (United States)

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

Stepien, D K; Püttmann, W

2014-05-01

180

Characterization of blood donors with high haemoglobin concentration  

DEFF Research Database (Denmark)

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

Magnussen, K; Hasselbalch, H C

2013-01-01

181

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)eriod. (Author)

182

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...15-minute period. 2. Dermal: Eye contact shall be prevented and skin contact with liquid benzene shall be limited. C. Appearance and odor: Benzene...if you inhale it, or if it comes in contact with your skin or eyes. Benzene...

2010-07-01

183

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...allergies and some drugs may raise the white...indication of benzene-induced toxicity. An...sign of benzene-induced toxicity. A less frequent...ultimately develop acute myelogenous leukemia...to have developed acute myelogenous leukemia...aplastic anemias induced by benzene...

2010-07-01

184

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

185

Densities and excess volumes of benzene + hexane between 298. 15 and 473. 15 K  

Energy Technology Data Exchange (ETDEWEB)

This paper reports the results of measurements of the densities for benzene + hexane using a high-pressure stainless steel pycnometer system at various temperatures between 298.15 and 473.15 K. The results were compared with those predicted by the Hankinson-Brobst-Thomson correlation (HBT) and the Spencer and Danner modified Rackett equation (SDR). The HBT equation showed an average deviation of about 0.74% from the experimental results while the SDR equation showed a 0.20% average absolute deviation. The excess molar volumes, V[sup E], calculated from the density values have been found to be positive for all the concentrations and temperatures considered.

Beg, S.A.; Tukur, N.M.; Al-Harbi, D.K.; Hamad, E.Z. (Kind Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia). Dept. of Chemical Engineering)

186

YAG nano-light sources with high Ce concentration  

CERN Document Server

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

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

2013-01-01

187

Serum concentration of high density lipoproteins (HDLs) in leishmaniotic dogs.  

Science.gov (United States)

In order to assess whether the concentration of high density lipoproteins (HDLs) changes in leishmaniotic dogs before and after treatment, HDL cholesterol (HDL-Chol and HDL%), C reactive protein (CRP) and activity of the antioxidant enzyme paraoxonase (PON-1) were measured in sera from 10 controls and 10 leishmaniotic dogs. Seven of these latter were sampled also 3, 7, 14, 21 and 28 days after treatment with antimonials and allopurinol. HDL-chol, and PON-1 were low in leishmaniotic dogs at admission and increased after treatment. HDL-chol and HDL% correlated positively with PON-1 and negatively with CRP suggesting that HDLs decrease through an oxidative mechanism. Therefore, HDLs may be used to monitor the magnitude of oxidation associated with inflammation in leishmaniotic dogs. PMID:25440996

Ibba, Fabrizio; Rossi, Gabriele; Meazzi, Sara; Giordano, Alessia; Paltrinieri, Saverio

2015-02-01

188

Catalytic wet air oxidation of high concentration pharmaceutical wastewater.  

Science.gov (United States)

In this study, we investigated the pretreatment of a high concentration pharmaceutical wastewater by catalytic wet air oxidation (CWAO) process. Different experiments were conducted to investigate the effects of the catalyst type, operating temperature, initial system pH, and oxygen partial pressure on the oxidation of the wastewater. Results show that the catalysts prepared by the co-precipitation method have better catalytic activity compared to others. Chemical oxygen demand (COD) conversion increased with the increase in temperature from 160 to 220 °C and decreased with the increase in pH. Moreover, the effect of the oxygen partial pressure on the COD conversion was significant only during the first 20 min of the reaction. Furthermore, the biodegradability of the wastewater improved greatly after CWAO, the ratio of BOD5/COD increased less than 0.1-0.75 when treated at 220 °C (BOD: biochemical oxygen demand). PMID:23676399

Zhan, Wei; Wang, Xiaocong; Li, Daosheng; Ren, Yongzheng; Liu, Dongqi; Kang, Jianxiong

2013-01-01

189

Gamma benzene hexachloride in guinea-pig brain after topical application.  

Science.gov (United States)

Blood and brain levels of gamma benzene hexachloride had been measured following topical application in guinea pigs. Levels increased with number of application, and the concentration in brain was at least 10 times greater than in blood. PMID:67157

Solomon, L M; West, D P; Fitzloff, J F; Becker, A M

1977-05-01

190

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

Directory of Open Access Journals (Sweden)

Full Text Available 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% cure in adult and 1% gamma benzene hexachloride (91.7% cure in children compared to benzyl benzoate emulsion.

Nag S C

1995-01-01

191

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-07-01

192

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

Science.gov (United States)

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

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

2015-02-01

193

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

Science.gov (United States)

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. PMID:18412960

Oren, Aharon

2008-01-01

194

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

OpenAIRE

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...

Nag S C; Barbhuiya J N; Datta P K; Banerjee P.P

1995-01-01

195

Modelling acceptance of sunlight in high and low photovoltaic concentration  

Science.gov (United States)

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

Leutz, Ralf

2014-09-01

196

Modelling acceptance of sunlight in high and low photovoltaic concentration  

International Nuclear Information System (INIS)

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

197

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

198

High pressure solid phases of benzene. I. Raman and x-ray studies of C6H6 at 294 K up to 25 GPa  

Science.gov (United States)

Crystalline benzene has been investigated at room temperature as a function of pressure up to 25 GPa in diamond anvil cells by Raman scattering and powder x-ray diffraction techniques. The concomitant spectroscopic and crystallographic results show the existence of numerous pressure-induced phases. Changes in the profiles of the Raman spectra and in the x-ray diffraction patterns, as well as changes in the variations of the Raman frequencies and the cell parameters with pressure indicate two first-order phase transitions at 1.4±0.1 and 4±1 GPa and a second-order one at 11±1 GPa. At 24 GPa the x-ray diffraction pattern seems to indicate the existence of a new phase. Two monoclinic structures are proposed for the phases above 1.5 GPa, in addition to the already known one. From these data, molar volume has been determined as a function of pressure and the Grüneisen parameters have been inferred in the different phases. Their pressure dependences are analyzed in the light of theoretical predictions. Arguments are given for a phase transformation at normal pressure and below 140 K or at room temperature below 1 GPa. A schematic P-T phase diagram is suggested and a controversy on the nature of the triple points located on the melting curve is clarified.

Thiéry, M. M.; Léger, J. M.

1988-10-01

199

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

200

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-04-15

201

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

Scientific Electronic Library Online (English)

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

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

2010-12-01

202

Point defect stabilization in ionic crystals at high defect concentrations  

International Nuclear Information System (INIS)

Stabilization of point defects in ionic crystals differs from that in metals or other monatomic solids in that there is the need to maintain both stoichiometry (or accommodate non-stoichiometry) and order. Primary point defects in these solids, whether produced thermally, chemically, or by irradiation, seldom are present or aggregate in exactly stoichiometric proportions, and in consequence at high defect concentrations extended secondary defect structures arise which can be quite distinct from those formed in monatomic solids. Non-stoichiometry can be accommodated in several ways. In oxygen-deficient transition metal oxides, oxygen vacancies can be effectively eliminated by alteration of the mode of linking metal-oxygen octahedra together, giving rise to so-called crystallographic shear planes. This process effectively delocalizes a change in cation valency. In cation deficient/anion excess systems (e.g. Fesub(1-x)O, UOsub(2+x), CaF2:YF3), accommodation occurs by a localized change in cation valency (and often position) and formation of point defect cluster complexes (cation vacancies, anion interstitials) which when stacked together can form embryonic nuclei for a new phase of altered stoichiometry. Where valency changes are not possible, for example in alkali halides or undoped alkaline earth halides and oxides, stoichiometric extended defects (such as dislocation loops) are generated, but these must be accompanied by other more stable forms oe accompanied by other more stable forms of point defect species. Aggregation of point defects at high density can additionally result in precipitation of separate elemental phases, and thus decomposition of the solid

203

Radical production in the radiolysis of benzene  

International Nuclear Information System (INIS)

Complete text of publication follows. Benzene is the prototypical aromatic compound and yet the radiation chemistry of the radicals formed in its radiolysis is not well understood. Temporal information on the yield of phenyl radical, the major radical produced in the radiolysis, is important for understanding the radiation chemistry of many other types of aromatic compounds including some polymers. The effects of track structure on the production of phenyl radicals have been examined using iodine-scavenging techniques. The variation of the yields of iodobenzene and the other major molecular products such as biphenyl as a function of iodine concentration gives a good indication of the competition kinetics occurring in particle tracks. Experimental results of the scavenger experiments will be shown and their implications in the radiolysis of condensed hydrocarbons will be discussed

204

Multiple liquid crystal phases of DNA at high concentrations  

Science.gov (United States)

DNA packaging in vivo is very tight, with volume concentrations approaching 70% w/v in sperm heads, virus capsids and bacterial nucleoids1-3. The packaging mechanisms adopted may be related to the natural tendency of semi-rigid polymers to form liquid crystalline phases in concentrated solutions4-8. We find that DNA forms at least three distinct liquid crystalline phases at concentrations comparable to those in vivo, with phase transitions occurring over relatively narrow ranges of DNA concentration. A weakly birefringent, dynamic, 'precholesteric' mesophase with microscopic textures intermediate between those of a nematic and a true cholesteric phase forms at the lowest concentrations required for phase separation. At slightly higher DNA concentrations, a second mesophase forms which is a strongly birefringent, well-ordered cholesteric phase with a concentration-dependent pitch varying from 2 to lO?m. At the highest DNA concentrations, a phase forms which is two-dimensionally ordered and resembles smectic phases of thermotropic liquid crystals observed with small molecules.

Strzelecka, Teresa E.; Davidson, Michael W.; Rill, Randolph L.

1988-02-01

205

Benzene biodegradation using an anaerobic column coupled to Mn(IV) reduction  

Energy Technology Data Exchange (ETDEWEB)

Benzene, toluene, and o, m, p-xylene compounds make up a large proportion of gasoline. Due to spills and leaks from underground tanks, these compounds frequently contaminate groundwater and sediment. In particular the high solubility of benzene makes it very mobile and an extra danger to groundwater. Moreover, there are strong links between benzene and cancer and thus benzene is considered a serious pollutant. Contaminated sites usually become anaerobic due to microbe action. In this study, benzene biodegradation was done in a glass column inoculated with anaerobic Rhine River sediment and using Mn(IV) as the final electron acceptor. Under steady state operation, benzene biodegradation efficiency was as high as 95 per cent. Carbon dioxide and Mn(II) recovery rates were 81 and 77 per cent respectively. Reactor sediment was withdrawn on day 104 and subject to DGGE profiling. This sediment showed different band patterns than the original sediment that was not exposed to benzene. The authors conclude that the species associated with the degradation of benzene are of the genus Propionibacterium and Actinomyces. 17 refs., 2 figs.

Villatoro-Monzon, W.R.; Velasquez-Mejia, E.K.; Morales-Ibarria, M.G.; Razo-Flores, E. [Instituto Mexicano del Petroleo (Mexico). Programo de Biotenologia del Petroleo

2004-07-01

206

Bandgap Engineering in High-Efficiency Multijunction Concentrator Cells  

Energy Technology Data Exchange (ETDEWEB)

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

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

2005-08-01

207

Benzene Mixing within a Large Tank Vapor Space - Comparison of Model Predictions and Field Data  

Energy Technology Data Exchange (ETDEWEB)

'Computer simulation helped Westinghouse Safety Management Solutions (WSMS) engineers demonstrate that benzene mixing within a large vapor space would proceed quickly enough to prevent the formation of a significant volume of gas above the LFL. This issue arose in the licensing of a nuclear waste processing operation that produced benzene as a byproduct. While experimental methods could only measure benzene concentration at a few discrete points, computational fluid dynamics measured it throughout the vapor space as a function of time. The analysis correlated well with physical measurements.'

Blanchard, A.

1999-07-08

208

Performance of silicone-on-glass Fresnel lenses in EMCORE's Gen 3 high-concentration concentrator photovoltaic system  

Science.gov (United States)

EMCORE's Concentrator Photovoltaic (CPV) systems use large-format Fresnel lenses to achieve 1090X concentration onto high-efficiency multi-junction solar cells. The use of Fresnel lenses is common in CPV systems due to their thin profile and light weight. EMCORE uses silicone-on-glass (SOG) lens technology, which provides a high-reliability, high-durability alternative to acrylic lenses. This paper describes performance variations of these lenses based on the Fresnel groove depth. Both the optical efficiency and temperature dependence of the optical system are evaluated as a function of groove depth.

Foresi, James S.; Hoffman, Rick; King, David; Ponsardin, Patrick

2012-10-01

209

Development of manufacturing capability for high-concentration, high-efficiency silicon solar cells  

Energy Technology Data Exchange (ETDEWEB)

This report presents a summary of the major results from a program to develop a manufacturable, high-efficiency silicon concentrator solar cell and a cost-effective manufacturing facility. The program was jointly funded by the Electric Power Research Institute, Sandia National Laboratories through the Concentrator Initiative, and SunPower Corporation. The key achievements of the program include the demonstration of 26%-efficient silicon concentrator solar cells with design-point (20 W/cm{sup 2}) efficiencies over 25%. High-performance front-surface passivations; that were developed to achieve this result were verified to be absolutely stable against degradation by 475 days of field exposure at twice the design concentration. SunPower demonstrated pilot production of more than 1500 of these cells. This cell technology was also applied to pilot production to supply 7000 17.7-cm{sup 2} one-sun cells (3500 yielded wafers) that demonstrated exceptional quality control. The average efficiency of 21.3% for these cells approaches the peak efficiency ever demonstrated for a single small laboratory cell within 2% (absolute). Extensive cost models were developed through this program and calibrated by the pilot-production project. The production levels achieved indicate that SunPower could produce 7-10 MW of concentrator cells per year in the current facility based upon the cell performance demonstrated during the program.

Sinton, R.A.; Verlinden, P.J.; Crane, R.A.; Swanson, R.N. [SunPower Corp., Sunnyvale, CA (United States)

1996-10-01

210

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

211

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

Science.gov (United States)

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

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

2014-05-21

212

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1990-05-01

213

Absorption of gamma benzene hexachloride following application of Kwell shampoo.  

Science.gov (United States)

Serum concentrations of gamma benzene hexachloride were determined in 9 children following application of 1% GBH shampoo for treatment of pediculosis capitis. GBH was present in the blood of all patients 2-24 hours following application. Four patients, who were retreated because of the persistence of living lice, had GBH in their pretreatment blood specimens. GBH levels in these latter patients were larger after retreatment than after the initial application, indicating that there may have been accumulation of the drug. PMID:6208543

Ginsburg, C M; Lowry, W

1983-07-01

214

Catalytic hydroxylation of benzene and toluene by an iron complex bearing a chelating di-pyridyl-di-NHC ligand.  

Science.gov (United States)

This work reports on iron-catalysed hydroxylation of benzene and toluene using aqueous H2O2. While benzene is hydroxylated with a high selectivity to phenol, toluene is hydroxylated to cresols with a high selectivity for the ortho and para-position. An inverse KIE indicates the presence of a high valent Fe=O species during catalysis. PMID:24840886

Raba, Andreas; Cokoja, Mirza; Herrmann, Wolfgang A; Kühn, Fritz E

2014-10-01

215

Carrier concentration and high T/sub c/ superconductivity  

International Nuclear Information System (INIS)

A systematic study of the influence of oxygen depletion on the carrier concentration and the occurence of superconductivity in a single-phase 1-2-3 Y-Ba-Cu-Oxide material is presented. This is accomplished by successive measurements of the Hall and electrical resistivities, ac-susceptibility, and x-ray diffraction on the same sample, in which the oxygen deficiency is controlled and determined from the thermogravimetry. With increasing oxygen depletion, the authors monitor how the 93K orthorhombic superconductor, with an estimated carrier concentration of 0.6 10/sup 22/ carriers/cm/sup 3/ at 100K, is transformed into a tetragonal semiconductor with a very low carrier concentration

216

Radiation defects in neutron irradiated silicon with high oxygen concentration  

International Nuclear Information System (INIS)

In silicon material with oxygen concentration in the range (4-9)x1017 cm-3, grown by the CZ method and irradiated by reactor neutrons, the interstitial oxygen mainly participates in A-center (V+O) creation. A-center concentration is linearly dependent on neutron fluence up to PHI=1018 n/cm2, value at which saturation occurs caused not by the exhaustion of dissolved oxygen but rather by vacancy-interstitial atom annihilation competitive mechanisms. A-center annealing (300 deg. C) does not lead to the full restoring of interstitial oxygen concentration. Repeating neutron irradiation and annealing causes a decrease of oxygen complex activity and the silicon behaves as a low-oxygen material

217

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

DEFF Research Database (Denmark)

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

Arayasiri, Manaswee; Mahidol, Chulabhorn

2010-01-01

218

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

International Nuclear Information System (INIS)

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

219

Unusually high concentrations in a fatal GHB case.  

Science.gov (United States)

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

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

2005-09-01

220

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.

221

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.

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

222

Differences in Swallowing between High and Low Concentration Taste Stimuli  

OpenAIRE

Taste is a property that is thought to potentially modulate swallowing behavior. Whether such effects depend on taste, intensity remains unclear. This study explored differences in the amplitudes of tongue-palate pressures in swallowing as a function of taste stimulus concentration. Tongue-palate pressures were collected in 80 healthy women, in two age groups (under 40, over 60), stratified by genetic taste status (nontasters, supertasters). Liquids with different taste qualities (sweet, sour...

Ahmed Nagy; Steele, Catriona M.; Pelletier, Cathy A.

2014-01-01

223

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

224

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

Science.gov (United States)

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

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

2014-09-01

225

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

Directory of Open Access Journals (Sweden)

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

Flynn John T

2008-02-01

226

Bio sensing Benzene in the refinery  

International Nuclear Information System (INIS)

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

227

Determination of water quality variables, endotoxin concentration, and enterobacteriaceae concentration and identification in Southern High Plains dairy lagoons  

Science.gov (United States)

The objectives of this study were to determine the concentration of endotoxin, determine 20 water quality variables, and identify and enumerate fungal and bacterial pathogens from United States southern High Plains dairy lagoons and control lakes during summer and winter. Water samples were collecte...

228

[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

229

Unexpectedly high indoor hydroxyl radical concentrations associated with nitrous acid.  

Science.gov (United States)

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

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

2013-08-13

230

Excess Thermodynamic Properties of Concentrated Aqueous Solutions at High Temperatures  

International Nuclear Information System (INIS)

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

231

Response of a Concentrated Monoclonal Antibody Formulation to High Shear  

OpenAIRE

There is concern that shear could cause protein unfolding or aggregation during commercial biopharmaceutical production. In this work we exposed two concentrated immunoglobulin-G1 (IgG1) monoclonal antibody (mAb, at >100 mg/mL) formulations to shear rates of between 20,000 and 250,000 s-1 for between 5 minutes and 30 ms using a parallel-plate and capillary rheometer respectively. The maximum shear and force exposures were far in excess of those expected during normal processing operations (20...

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

2009-01-01

232

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)

233

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

Science.gov (United States)

...repeated or prolonged contact with the skin. High...Signs and Symptoms Direct skin contact with benzene may cause...further and to refer the patient if repeat tests confirm...about two percent of patients who ultimately...

2010-10-01

234

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1985-12-01

235

Declines in insectivorous birds are associated with high neonicotinoid concentrations.  

Science.gov (United States)

Recent studies have shown that neonicotinoid insecticides have adverse effects on non-target invertebrate species. Invertebrates constitute a substantial part of the diet of many bird species during the breeding season and are indispensable for raising offspring. We investigated the hypothesis that the most widely used neonicotinoid insecticide, imidacloprid, has a negative impact on insectivorous bird populations. Here we show that, in the Netherlands, local population trends were significantly more negative in areas with higher surface-water concentrations of imidacloprid. At imidacloprid concentrations of more than 20 nanograms per litre, bird populations tended to decline by 3.5 per cent on average annually. Additional analyses revealed that this spatial pattern of decline appeared only after the introduction of imidacloprid to the Netherlands, in the mid-1990s. We further show that the recent negative relationship remains after correcting for spatial differences in land-use changes that are known to affect bird populations in farmland. Our results suggest that the impact of neonicotinoids on the natural environment is even more substantial than has recently been reported and is reminiscent of the effects of persistent insecticides in the past. Future legislation should take into account the potential cascading effects of neonicotinoids on ecosystems. PMID:25030173

Hallmann, Caspar A; Foppen, Ruud P B; van Turnhout, Chris A M; de Kroon, Hans; Jongejans, Eelke

2014-07-17

236

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

OpenAIRE

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

Weiner, Jonathan M.; Lovley, Derek R.

1998-01-01

237

Adverse Effect of High Glucose Concentration on Stem Cell Therapy  

Directory of Open Access Journals (Sweden)

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

Najmaldin Saki

2013-07-01

238

Investigation into adsorption and photocatalytic degradation of gaseous benzene in an annular fluidized bed photocatalytic reactor.  

Science.gov (United States)

The adsorption and photocatalytic degradation of gaseous benzene were investigated considering the operating variables and kinetic mechanism using nano-titania agglomerates in an annular fluidized bed photocatalytic reactor (AFBPR) designed. The special adsorption equilibrium constant, adsorption active sites, and apparent reaction rate coefficient of benzene were determined by linear regression analysis at various gas velocities and relative humidities (RH). Based on a series of photocatalytic degradation kinetic equations, the influences of operating variables on degradation efficiency, apparent reaction rate coefficient and half-life were explored. The findings indicated that the operating variables have obviously influenced the adsorption/photocatalytic degradation and corresponding kinetic parameters. In the photocatalytic degradation process, the relationship between photocatalytic degradation efficiency and RH indicated that water molecules have a dual-function which was related to the structure characteristics of benzene. The optimal operating conditions for photocatalytic degradation of gaseous benzene in AFBPR were determined as the fluidization number at 1.9 and RH required related to benzene concentration. This investigation highlights the importance of controlling RH and benzene concentration in order to obtain the desired synergy effect in photocatalytic degradation processes. PMID:25205352

Geng, Qijin; Tang, Shankang; Wang, Lintong; Zhang, Yunchen

2015-03-01

239

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

International Nuclear Information System (INIS)

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

240

Occurrence of benzene as a heat-induced contaminant of carrot juice for babies in a general survey of beverages.  

Science.gov (United States)

A survey of benzene contamination of 451 beverage samples, using headspace sampling combined with gas chromatography and mass spectrometry (HS-GC/MS) with a quantification limit of 0.13 microg l(-1), was conducted. Artefactual benzene formation during headspace sampling was excluded by gentle heating at 50 degrees C only and adjustment of sample pH to 10. The incidence of benzene contamination in soft drinks, beverages for babies, alcopops and beer-mixed drinks was relatively low, with average concentrations below the EU drinking-water limit of 1 microg l(-1). Significantly higher concentrations were only found in carrot juice, with the highest levels in carrot juice specifically intended for infants. About 94% of 33 carrot juice for infants had detectable benzene levels, with an average concentration of 1.86 +/- 1.05 microg l(-1). Benzene contamination of beverages was significantly correlated to iron and copper concentrations, which act as catalyst in benzene formation. The formation of benzene in carrot juice was predominantly caused by a heat-induced mechanism, which explains the higher levels in infant carrot juices that are subject to higher heat-treatment to exclude microbiological contamination. PMID:18608484

Lachenmeier, Dirk W; Reusch, Helmut; Sproll, Constanze; Schoeberl, Kerstin; Kuballa, Thomas

2008-10-01

241

BREEDING STUDIES IN POTATOES CONTAINING HIGH CONCENTRATIONS OF ANTHOCYANINS  

Science.gov (United States)

Studies of the breeding behavior of clones containing high levels of anthocyanins were conducted. Red flesh clones appeared in proportions suggesting multigenic control of degree of pigmentation. Red flesh and purple flesh clones were always accompanied by red and purple skin, respectively. Red f...

242

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

OpenAIRE

The sorbitol presents several industrial applications and its conventional production is of high cost and low yield. Sorbitol production by Zymomonas mobilis production has attracted attention as both production cost and environmental impact are low. The sorbitol plays an osmo-protective rule so that its production is promoted by high sugar concentrations. This work has evaluated the effect of high sucrose concentration in the sorbitol production. The raise of sucrose concentration from 100 t...

Rui Sérgio dos Santos Ferreira da Silva; João Batista Buzato; Maria Antonia Pedrine Colabone Celligoi; Marcos Roberto Oliveira

2004-01-01

243

Benzene-hydrogen halide interactions: Theoretical studies of binding energies, vibrational frequencies, and equilibrium structures  

Science.gov (United States)

High level ab initio calculations have been performed on the benzene-HCl and benzene-HF systems using the second-order Møller-Plesset perturbation theory. In contrast to existing theoretical studies, the calculated binding energies indicate that HCl binds more strongly to benzene than HF. This is in accordance with the limited experimental data available on these systems. An explanation has been forwarded for the above observation by performing a molecular orbital analysis of both C6H6⋯HF and C6H6⋯HCl. In the global minimum of C6H6⋯HF, HF lies inclined to the benzene ring with the hydrogen atom pointing either towards a benzene carbon or the center of carbon-carbon bond. In the C6H6⋯HCl complex, HCl is found to lie along the C6 axis of the benzene ring for smaller basis sets, but it also tends to lie inclined to the benzene ring for a very large basis set. The quantum mechanical probabilistic characterization of the structure of the C6H6⋯HCl complex provides a more realistic description of the experimental equilibrium structure. The van der Waals modes have also been characterized, and the modulation of these modes as one progresses from HF to HCl has also been studied.

Tarakeshwar, P.; Lee, Sang Joo; Lee, Jin Yong; Kim, Kwang S.

1998-05-01

244

Response of a concentrated monoclonal antibody formulation to high shear.  

Science.gov (United States)

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

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

2009-08-01

245

Studies on the mechanism of benzene toxicity  

International Nuclear Information System (INIS)

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

246

Studies on the mechanism of benzene toxicity  

Energy Technology Data Exchange (ETDEWEB)

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

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

1989-07-01

247

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

248

Reverse isotope dilution method for determining benzene and metabolites in tissues  

Energy Technology Data Exchange (ETDEWEB)

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

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

1988-07-01

249

Reverse isotope dilution method for determining benzene and metabolites in tissues  

International Nuclear Information System (INIS)

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

250

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1999-08-01

251

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

International Nuclear Information System (INIS)

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

252

Highly efficient transduction of repopulating bone marrow cells using rapidly concentrated polymer-complexed retrovirus  

International Nuclear Information System (INIS)

Using the cationic polymer, Polybrene, and the anionic polymer, chondroitin sulfate C, we concentrated recombinant retrovirus pseudotyped with an ecotropic envelope, which is susceptible to inactivation by high-speed concentration methods. To evaluate gene marking, murine bone marrow was harvested from C3H mice, transduced with polymer-concentrated GFP virus, and transplanted into lethally irradiated recipients. Total gene marking in mice averaged 30-35% at 8 weeks post-transplant and transgene expression remained stable for over 16 weeks. Using the polymer concentration method, a second retroviral vector encoding the drug resistant variant of dihydrofolate reductase (L22Y-DHFR) was concentrated and tested. Approximately 40% of transduced murine bone marrow progenitor cells were protected against trimetrexate concentrations that completely eliminated the growth of non-modified cells. These results show that anionic and cationic polymers can be combined to rapidly concentrate viruses that are normally difficult to concentrate, and the concentrated virus efficiently transduces hematopoietic stem cells

253

Lithium Mediated Benzene Adsorption on Graphene and Graphene Nanoribbons  

OpenAIRE

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

Krepel, Dana; Hod, Oded

2013-01-01

254

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

OpenAIRE

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...

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

2007-01-01

255

Radiocarbon dating methods using benzene liquid scintillation  

International Nuclear Information System (INIS)

The radiocarbon dating method using benzene liquid scintillation is reported in detail. The results of measurement of NBS oxalic acid agree with the recommended value, indicating that isotopic fractionation during benzene synthesis can be negligible. Ten samples which have been already measured by gas counter are dated by benzene liquid scintillation. There is no significant difference in age for the same sample between benzene liquid scintillation and gas counters. It is shown that quenching has to be corrected for the young sample. Memory effect in stainless steel reaction vessel can be removed by using an exchangeable inner vessel and by baking it in the air. Using this method, the oldest age that can be measured with 2.3 g carbon is 40,000 years B.P. (author)

256

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...life. (3) Respirator selection. (i) Employers must...locations remote from the site at which benzene is handled...disposing in a sanitary landfill; (b) if small quantities...circumvented by proper selection of HPLC...

2010-07-01

257

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

258

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...repeated or prolonged contact with the skin...and Symptoms Direct skin contact with benzene may...or refer the patient if repeat tests...relatively few patients have been studied...performed by portable direct reading...

2010-07-01

259

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...swallowed and the patient is conscious...or skin/eye contact) under emergency...and to record the results obtained. When...Symptoms Direct skin contact with benzene may...Repeated or prolonged contact may result in...

2010-07-01

260

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

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

2010-07-01

261

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

OpenAIRE

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

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

2002-01-01

262

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

OpenAIRE

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

Irina Masalova; Karina Kovalchuk

2012-01-01

263

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

International Nuclear Information System (INIS)

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

264

MICROSTRUCTURAL PROPERTIES OF HIGH-LEVEL WASTE CONCENTRATES AND GELS WITH RAMAN AND INFRARED SPECTROSCOPIES  

Science.gov (United States)

Nearly half of the high level radioactive waste stored at Hanford is composed of highly alkaline concentrates referred to as either salt cakes or Double-Shell Slurry (DSS), depending on their compositions and processing histories. The major components of these concentrates are wa...

265

Photoionization spectrum of liquid benzene  

Energy Technology Data Exchange (ETDEWEB)

The photocurrent from neat liquid benzene has been studied for excitation energies from threshold to 10.3 eV and for externally applied electric fields from 1 to 50 kV/cm. Using a power law fit to the energy dependence of the threshold current, an onset of [epsilon][sub t] = 7.65 [+-] 0.1 eV has been obtained. The field dependence was fit to an exponential radial probability density for thermalized ion-pair separation distances with an average separation distance of [r] = 23 [+-] 2 A at an excitation energy, [epsilon] of 8.86 eV (1.2 eV above threshold). Photocurrent was too weak to establish a dependence of [r] on excitation energy. The quantum yield for photocurrent at 8.86 eV was determined by comparison with the photocurrent from TMPD in 2,2,4-trimethylpentane (isooctane) to be 6.5 [times] 10[sup [minus]4] at zero field. From this, the intrinsic molecular ionization probability at [epsilon] = 8.86 eV was determined to be 0.6 [+-] 0.3. 30 refs., 5 figs.

Saik, V. O.; Lipsky, S. (Univ. of Minnesota, Minneapolis, MN (United States))

1994-11-17

266

Studies on the mechanism of benzene toxicity.  

OpenAIRE

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

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

1989-01-01

267

Formation of benzene in the interstellar medium  

OpenAIRE

Polycyclic aromatic hydrocarbons and related species have been suggested to play a key role in the astrochemical evolution of the interstellar medium, but the formation mechanism of even their simplest building block—the aromatic benzene molecule—has remained elusive for decades. Here we demonstrate in crossed molecular beam experiments combined with electronic structure and statistical calculations that benzene (C6H6) can be synthesized via the barrierless, exoergic reaction of the ethyn...

Jones, Brant M.; Zhang, Fangtong; Kaiser, Ralf I.; Jamal, Adeel; Mebel, Alexander M.; Cordiner, Martin A.; Charnley, Steven B.

2011-01-01

268

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

269

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

270

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

Directory of Open Access Journals (Sweden)

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

Sulaiman Siti

2011-08-01

271

Geometry of Benzene from the Infrared Spectrum  

Science.gov (United States)

The structure of benzene is fully determined once the interatomic distances rcc and rCH are obtained from experimental data. This infrared spectroscopy experiment allows the determination of rcc and rCH from the rotational analysis of an infrared active band of C6H6 and one of its isotopomers, C6D6. Here the P and R branches of the n4 parallel band of C6H6 (674 cm-1) and of C6D6 (496 cm-1) are analyzed to determine the rotational constants B0 of the ground state of both isotopomers. From B0 values the moments of inertia are calculated and the rCC and rCH distances are obtained. The requirements of the experiment are availability of an IR spectrometer equipped with a KBr beam-splitter working at 0.2 cm-1 of resolution and a short cylindrical cell fitted with KBr windows. High-performance infrared detectors are not required because the bands recorded are the strongest in the spectrum. To fit the experimental wavenumbers of the R and P branch lines at least a second degree polynomial is needed. Such a mathematical tool is generally available on a PC. The values obtained agree fairly well with the literature data for the rotational analysis of high-resolution spectra. The aim of the experiment can be extended to allow the calculation of centrifugal distortion constants, transition moments, and anharmonic constants.

Cané, Elisabetta; Miani, Andrea; Trombetti, Agostino

1999-09-01

272

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

International Nuclear Information System (INIS)

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

273

Dissociative electron attachment to laser-excited benzene  

International Nuclear Information System (INIS)

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

274

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...concentration might be high without proper safety...Specific Gravity (water=1): 0.879 3...F): 75 mm Hg 6. Solubility in Water: .06% 7. Evaporation...Miscellaneous Precautions A. High exposure to...

2010-07-01

275

High plasma adrenomedullin concentrations in patients with high-renin essential hypertension.  

Science.gov (United States)

Adrenomedullin (AM) is a novel peptide, first isolated from human phaeochromocytoma, which elicits a long-lasting vasorelaxant activity. Recently, it has been reported that endothelial cells produce AM and that immunoreactive AM plasma levels may be elevated in human arterial hypertension, although the exact pathophysiological role of AM remains to be established. The aim of our study was to determine the relationship between the components of the enin-angiotensin-aldosterone system (RAAS) and plasma AM levels in patients with low-, medium- or high- renin essential hypertension. The study groups included 10 patients with low-renin essential hypertension (average age 42+15 years), nine patients with medium-renin essential hypertension (46+13 years), 11 patients with high-renin essential hypertension (42+14 years) and 12 healthy subjects (43+11 years). Our results demonstrated that the mean AM values of all patients with essential hypertension were 10.85+3.14 pg/ml; there was a statistical correlation (r=0.705; p<0.001) between plasma renin activity (PRA) and AM levels in hypertensives. In patients with high-renin essential hypertension, plasma AM levels (14.2+2.2 pg/ml) were significantly higher (p<0.001) than those of healthy subjects (8.7+2.1 pg/ml), patients with medium-renin essential hypertension (8.5+1.4 pg/ml), and patients with low-renin essential hypertension (9.1+1.5 pg/ml). There was no statistical difference in AM concentrations between medium- and low-renin hypertensive patients. In conclusion, we have found that, in hypertensive patients, plasma AM levels were increased only in high-renin individuals, suggesting a role of AM in this particular form of human essential hypertension. PMID:12228854

Letizia, Claudio; Subioli, Stefano; Cerci, Sabrine; Caliumi, Chiara; Verrelli, Cristiana; Delfini, Enrica; Celi, Massimiliano; Scuro, Luigi; D' Erasmo, Emilio

2002-06-01

276

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).

277

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

Science.gov (United States)

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

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

2005-01-01

278

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

279

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

International Nuclear Information System (INIS)

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

280

Radiolysis of alkyl benzene sulfonate (ABS) in aqueous solution  

International Nuclear Information System (INIS)

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

281

Effects of toluene and benzene air mixtures on human lung cells (A549).  

Science.gov (United States)

Human epithelial lung cells (A549) were exposed to toluene and benzene in the air as individual compounds and mixtures at concentrations of about 0.25ppmv in a specifically adapted fumigation device. Possible early toxicological effects at cellular level have been determined by lactate dehydrogenase (LDH), glutathione redox status (GSH) and comet assay. An hour of exposure to 0.25ppmv of toluene in the air induced DNA damages which were repaired within 24h after the treatment. No DNA damage was detected by applying a similar concentration of benzene, but there was a decrease in the glutathione ratio. Exposure to a mixture of toluene and benzene in air led to an increase in the cytotoxic effect and DNA damage without any further repair, but did not induce any changes in the glutathione redox status. PMID:19046626

Pariselli, F; Sacco, M G; Ponti, J; Rembges, D

2009-07-01

282

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

DEFF Research Database (Denmark)

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

Kosiorowska, Anna Katarzyna; Puggaard, Liselotte

2011-01-01

283

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

Science.gov (United States)

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

Mondal, Mohan; Prakash, Bukkaraya Samudram

2007-04-01

284

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

285

Vibrational relaxation of phenol in benzonitrile and benzene solutions  

Science.gov (United States)

The Raman bandwidths and the frequency shifts of the ? 12(A 1) mode and the IR ? 3(OH) stretching mode of phenol and phenol-OD have been measured as a function of concentration in benzonitrile and benzene solutions. Opposite isotope effects of deuterium substitution in the hydroxyl group of phenol on the bandwidths of the ? 12 and the ? 3(OH) modes have been found. The experimental bandwidths are discussed in terms of available theoretical models for dephasing and other mechanisms of broadening. The isolated binary collision dephasing model of Fischer-Laubereau, the Knapp-Fischer concentration-fluctuation model and the Robertson-Yarwood model have been tested. It has been stated that the purely repulsive potential is responsible for vibrational dephasing of the ? 12 mode of phenol in benzene while the concentration-fluctuation model reproduces the experimental data for that mode in benzonitrile. The coupling between the ? 3(OH) and ? 2(OH…N) modes is the dominant mechanism for broadening of the ? 3(OH) mode of phenol in benzonitrile.

Abramczyk, H.; Reimsch?ssel, W.; Bara?ska, H.; ?abudzi?ska, A.

1985-04-01

286

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

OpenAIRE

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...

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

2009-01-01

287

Determination of synovial fluid hyaluronate concentration and polymerisation by high performance liquid chromatography.  

OpenAIRE

High performance liquid chromatography (HPLC) with a size exclusion column and ultraviolet monitoring was used to study the effect of synovial fluid hyaluronate concentration and degree of polymerisation on viscosity and mucin clot formation. Rotational viscometry measurements showed an exponential relation between the synovial fluid hyaluronate concentration and relative viscosity, the viscosity increasing particularly steeply with hyaluronate concentrations exceeding 2-2.5 mg/ml. The scatte...

Saari, H.; Konttinen, Y. T.

1989-01-01

288

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

OpenAIRE

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

289

A Simple Route towards High-Concentration Surfactant-Free Graphene Dispersions  

OpenAIRE

A simple solvent exchange method is introduced to prepare high-concentration and surfactant-free graphene liquid dispersion. Natural graphite flakes are first exfoliated into graphene in dimethylformamide (DMF). DMF is then exchanged by terpineol through distillation, relying on their large difference in boiling points. Graphene can then be concentrated thanks to the volume difference between DMF and terpineol. The concentrated graphene dispersions are used to fabricate tran...

Li, Jiantong; Ye, Fei; Vaziri, Sam; Muhammed, Mamoun; Lemme, Max C.; O?stling, Mikael

2012-01-01

290

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.

291

Adsorption of trichloroethylene and benzene vapors onto hypercrosslinked polymeric resin  

Energy Technology Data Exchange (ETDEWEB)

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.

Liu Peng [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China); Long Chao, E-mail: clong@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China); State Environmental Protection Engineering Center for Organic Chemical Industrial Waste Water Disposal and Resources Reuse, Nanjing 210046 (China); Jiangsu Engineering Research Center for Organic Pollution Control and Resources Reuse, Nanjing 210046 (China); Li Qifen [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China); Qian Hongming [State Environmental Protection Engineering Center for Organic Chemical Industrial Waste Water Disposal and Resources Reuse, Nanjing 210046 (China); Jiangsu Engineering Research Center for Organic Pollution Control and Resources Reuse, Nanjing 210046 (China); Li Aimin; Zhang Quanxing [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210093 (China); State Environmental Protection Engineering Center for Organic Chemical Industrial Waste Water Disposal and Resources Reuse, Nanjing 210046 (China); Jiangsu Engineering Research Center for Organic Pollution Control and Resources Reuse, Nanjing 210046 (China)

2009-07-15

292

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

293

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

294

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

Directory of Open Access Journals (Sweden)

Full Text Available This paper focuses on the effects of the PSt content of polystyrene (PSt-poly (dimethylsiloxane (PDMS interpenetrateing network (IPN polymer membranes, on the pervaporation (PV characteristics during the removal of benzene from an aqueous solution of dilute benzene. When an aqueous solution of 0.05wt% benzene was permeated through the PSt-PDMS IPN membranes, they showed high benzene/water selectivity. Both the permeability and the benzene/water selectivity of the membranes were enhanced with increasing PSt content in the PSt-PDMS IPN membrane. The physicochemical mechanism of permeation and separation through the PSt-PDMS IPN membranes during PV is also discussed. The best normalized permeation rate, separation factor for benzene selectivity, and PV separation index of the PSt-PDMS IPN membrane were 1.27 × 10-6 kgm (m2hr-1, 3293, and 41821, respectively. These PV characteristics are discussed from the viewpoint of the chemical and physical structure of the PSt-PDMS IPN membranes.

Tatsuo Yajima

2011-03-01

295

High pressure solid phases of benzene. II. Calculations of the vibration frequencies and evolution of the bonds in C6H6 and C6D6 up to 20 GPa  

Science.gov (United States)

The complete vibrational spectra of crystalline C6H6 and C6D6 have been calculated for the different pressure-induced solid phases recently determined at 293 K up to 25 GPa, and compared to Raman scattering data. The normal coordinate analysis has been carried out by using intermolecular Buckingham-type atom-atom interactions and the intramolecular force field of the free molecule. Results of such frequency calculations are compared to experimental values at ambient pressure. The variation of the relevant crystalline parameters is discussed to construct a model and calculate the vibrational frequencies under pressure. The quantitative fit of the frequency shift of the Raman active modes under pressure demonstrates the necessity of including different C-C and C-H (C-D) bond compressibilities within the benzene molecule. Such intramolecular distance variations which allow to estimate the frequency corrections for the totally symmetric (a1g) breathing modes, have been determined from the observed pressure-frequency dependence of these internal modes. The behavior of other nonsymmetric (e2g) internal modes which become comparatively weak under pressure, suggests a charge delocalization within—and possibly out of—the benzene ring, eventually leading to irreversible opening of the hexagonal cycle. This can be directly related to the irreversible transformation of benzene to a polymer which is observed after pressurization above 20 GPa.

Thiéry, M. M.; Besson, J. M.; Bribes, J. L.

1992-02-01

296

Ultra-high concentration effects in multi-junction solar cells  

Science.gov (United States)

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

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

2005-08-01

297

Benzene exposure on a crude oil production vessel  

Energy Technology Data Exchange (ETDEWEB)

Objectives: The aim was to describe the personal exposure to benzene on a typical crude oil production vessel and to identify factors influencing the exposure level. Methods: The study population included process operators, deck workers, mechanics and contractors on a production vessel in the Norwegian sector of the North Sea. The personal exposure to benzene during ordinary activity, during a short shutdown and during tank work was monitored using organic vapour passive dosimeter badges (3MTM3500). Information on the tasks performed on the day of sampling was recorded. Exposure was assessed by grouping the measurements according to job category, mode of operation and the tasks performed on the sampling day. Univariate analysis of variance was used to test the differences between the groups. Results: Forty-two workers participated in the exposure assessment, comprising a total of 139 measurements. The arithmetic and geometric mean of benzene exposure for all measurements was 0.43 and 0.02 p.p.m., respectively. Twenty-five measurements (18%) were below the limit of detection (0.001 p.p.m.), while ten samples (7%) exceeded the occupational exposure limit of 0.6 p.p.m. The geometric mean exposure was 0.004 p.p.m. (95% CI 0.003-0.006) during ordinary activity, 0.01 p.p.m. (95% CI 0.005-0.02) during shutdown and 0.28 p.p.m. (95% CI 0.16-0.49) during tank work. Workers performing annual cleaning and maintenance of tanks containing crude oil or residues of crude oil had higher levels of exposure than workers performing other tasks, including work near open hydrocarbon-transport systems (all P < 0.001). However, because of the mandatory use of respirators, the actual personal benzene exposure was lower. The job categories explained only 5% of the variance in exposure, whereas grouping by mode of operation explained 54% of the variance and grouping by task 68%. Conclusion: The results show that, although benzene exposure during ordinary and high activity seems to be low in the processing area on the production vessel, cleaning of tanks and performing maintenance work in a cleaned tank have a potential for high exposure. (author)

Kirkeleit, J; Riise, T.; Bratveit, M.; Moen, B.E. [University of Bergen (Norway). Dept. of Public Health and Primary Health Care

2006-07-01

298

Radiation dose in mass screening for gastric cancer with high-concentration barium sulphate compared with moderate-concentration barium sulphate  

International Nuclear Information System (INIS)

Full text: Recently, high-concentration barium sulfate has been developed and is used in many medical facilities. This study compared radiation dose using high-concentration and moderate-concentration barium sulfate. The dose was evaluated with an experimental method using a gastric phantom and with a clinical examination. In the former, the dose and X-ray tube load were measured on the phantom with two concentrations of barium sulfate. In the latter, the fluoroscopic dose-area product (DAP), the radiographic DAP and their sum, the total DAP, were investigated in 150 subjects (112 males, 38 females) treated with both concentrations of barium sulfate. The effective dose was calculated by the software of PCXMC in every case. The results of the experimental evaluation indicated that the effective dose and X-ray tube load were greater with high-concentration barium sulfate than with moderate-concentration barium sulfate (p < 0.05). The results of the clinical evaluation indicated that the fluoroscopic DAP was greater with moderate-concentration barium sulfate than with high-concentration barium sulfate (p < 0.05), but the radiographic DAP was quite the reverse, so the total DAP and effective dose were almost same with both concentrations of barium sulfate. We conclude that high-concentration barium sulfate does not increase radiation dose in mass screening for gastric cancer.

299

Combustion of hydrogen at high concentrations including the effect of obstacles  

International Nuclear Information System (INIS)

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

300

Compact high-flux two-stage solar collectors based on tailored edge-ray concentrators  

Science.gov (United States)

Using the recently-invented tailored edge-ray concentrator (TERC) approach for the design of compact two-stage high-flux solar collectors--a focusing primary reflector and a nonimaging TERC secondary reflector--we present: 1) a new primary reflector shape based on the TERC approach and a secondary TERC tailored to its particular flux map, such that more compact concentrators emerge at flux concentration levels in excess of 90% of the thermodynamic limit; and 2) calculations and raytrace simulations result which demonstrate the V-cone approximations to a wide variety of TERCs attain the concentration of the TERC to within a few percent, and hence represent practical secondary concentrators that may be superior to corresponding compound parabolic concentrator or trumpet secondaries.

Friedman, Robert P.; Gordon, Jeffrey M.; Ries, Harald

1995-08-01

301

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

302

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

Scientific Electronic Library Online (English)

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

Karina, Kovalchuk; Irina, Masalova.

303

Low Cefepime Concentrations during High Blood and Dialysate Flow Continuous Venovenous Hemodialysis  

OpenAIRE

Dosing of cefepime during high blood flow (Qb; 300 ml/min), high dialysate flow (Qd; 3 liter/h) continuous venovenous hemodialysis (CVVHD) is undefined. Six patients on CVVHD had serum and effluent cefepime concentrations measured at 0.5, 1, 2, 6, and 12 h after dosing. Three patients had cefepime concentrations less than the MIC for Pseudomonas aeruginosa. A dose of 2,000 mg every 12 h or 1,000 mg every 8 h may increase time at a therapeutic concentration.

Wilson, F. Perry; Bachhuber, Marcus A.; Caroff, Daniel; Adler, Rebecca; Fish, Douglas; Berns, Jeffrey

2012-01-01

304

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

International Nuclear Information System (INIS)

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

305

Probing concentrator solar cell performance at high flux with localized irradiation  

Science.gov (United States)

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

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

2006-08-01

306

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 ...

307

Doping of high concentration of Beryllium in GaAs layers, by molecular-beam epitaxy  

International Nuclear Information System (INIS)

Doping processes of high concentrations of Be in GaAs layers by molecular-beam epitaxy (MBE) at low temperatures with different growth rates were investigated in order to explore the possibility of the low-temperature MBE growth for obtaining highly non-equilibrium structures. A high concentration of acceptor Be atoms with a hole concentration of 5.65 x 1020 cm-3 were obtained with a substrate temperature 300 oC and a low growth rate 0.03 ?m/h, while an increase in either the substrate temperature or the growth rate resulted in lower hole concentrations. These results suggest unique properties of the low-temperature MBE growth; long-distance diffusions of solute atoms are inhibited at a low growth temperature, while a low growth rate gives surface or near-surface atoms a sufficient time to form a low-energy configuration at a low growth temperature.

308

Growth-inhibitory effect of a high glucose concentration on osteoblast-like cells.  

Science.gov (United States)

Impaired bone formation resulting from a decline of osteoblast activity has been implicated in the pathogenesis of diabetic osteopenia. We examined the effects of high glucose concentration alone, independent of insulin deficiency, on the growth of a human osteoblast-like cell line (MG-63). Sustained exposure to high glucose for 7 days inhibited cell growth in a concentration-dependent manner up to 49.5 mmol/L, as compared with cells cultured with a normal glucose concentration (5.5 mmol/L) or a high mannitol concentration (an iso-osmolar control). Glucose (49.5 mmol/L) attenuated the increment either in DNA content or in [3H]thymidine incorporation induced by insulin-like growth factor I (IGF-I). The IGF-I-induced increase of ornithine decarboxylase (ODC) activity, which plays an important role in cell growth, was also attenuated. The half-life of ODC protein was not shortened by the high glucose culture, but the intracellular content of putrescine (an end product of ODC) was significantly decreased. These changes did not occur in the high mannitol culture, strongly suggesting a specific effect of glucose. In summary, our observations suggest that a high glucose concentration significantly impairs the proliferative response of osteoblastic cells to IGF-I and that the defective cell function caused by sustained exposure to high glucose levels might contribute to impaired bone formation in patients with diabetic osteopenia. PMID:9437509

Terada, M; Inaba, M; Yano, Y; Hasuma, T; Nishizawa, Y; Morii, H; Otani, S

1998-01-01

309

Irradiation with benzene, toluene and phenol electron beams in aqueous solution  

International Nuclear Information System (INIS)

It is described a methodology for waste water treatment which is simulated doing a benzene-toluene-phenol mixture in aqueous solution. Three different concentrations of them ones were used which were irradiated with electron beams coming from a Pelletron Accelerator carrying out the degradation effect of these compounds in CO2 and H2O. By mean of gas chromatography the analytical determinations were realized finding that in lower concentration of benzene and toluene performances of degradation higher than 95 % were obtained, but higher concentrations (100 ppm) the performance diminishes at 89 %, while for phenol in higher concentrations its degradation is over 60 % and in lower concentrations the degradation is under 80 %. The results are obtained with a constant irradiation time of 12 seconds and neutral pH. (Author

310

2-Bromo-1,3-bis[2-(2-naphthyl)vinyl]benzene benzene hemisolvate and 9-bromodinaphth[1,2-a:2',1'-j]anthracene.  

Science.gov (United States)

2-Bromo-1,3-bis[2-(2-naphthyl)vinyl]benzene benzene hemisolvate, C(30)H(21)Br·0.5C(6)H(6), (I), with two formula units in the asymmetric unit, exists in the crystal structure in a conformation in which the trans (2-naphthyl)vinyl substituents on the central bromobenzene moiety appear as nearly fully extended `wings', while 9-bromodinaphth[1,2-a:2',1'-j]anthracene, C(30)H(17)Br, (II), adopts a highly nonplanar `manta-ray' shape, with the H atoms in the interior of the molecule within van der Waals contact distances. The packing of the significantly twisted molecules of (I) generates large voids which are filled by benzene solvent molecules, while molecules of (II) stack compactly with all C-Br bonds parallel within the stack. PMID:21206083

Mague, Joel T; Chudomel, J Matthew; Lahti, Paul M

2011-01-01

311

A Nonlinear Optical Experiment: Stimulated Raman Scattering in Benzene and Deuterated Benzene  

Science.gov (United States)

A nonlinear optical experiment is presented that utilizes a doubled Nd:YAG laser to produce stimulated Raman scattering (SRS) in benzene and deuterated benzene. A sampling arrangement is described that results in strong stimulated Raman emission involving symmetric CC and CH(CD) stretching modes in both C6H6 and C6D6. The wavelengths of the coherent beams are easily measured with a simple transmission grating and meter stick. Observations of both collinear and conical stimulated Raman beams are made and the reasons for these discussed. The measured frequencies permit calculation of CC and CH force constants in benzene.

Melin, Stéphanie; Nibler, Joseph W.

2003-10-01

312

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

313

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

International Nuclear Information System (INIS)

Benzene has been detected in Titan's atmosphere by Cassini instruments, with concentrations ranging from sub-ppb in the stratosphere to ppm in the ionosphere. Sustained levels of benzene in the haze formation region could signify that it is an important reactant in the formation of Titan's organic aerosol. To date, there have not been laboratory investigations to assess the influence of benzene on aerosol properties. We report a laboratory study on the chemical composition of organic aerosol formed from C6H6/CH4/N2 via far ultraviolet irradiation (120-200 nm). The compositional results are compared to those from aerosol generated by a more ''traditional Titan'' mixture of CH4/N2. Our results show that even a trace amount of C6H6 (10 ppm) has significant impact on the chemical composition and production rates of organic aerosol. There are several pathways by which photolyzed benzene may react to form larger molecules, both with and without the presence of CH4, but many of these reaction mechanisms are only beginning to be explored for the conditions at Titan. Continued work investigating the influence of benzene in aerosol growth will advance understanding of this previously unstudied reaction system.

314

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

Energy Technology Data Exchange (ETDEWEB)

Benzene has been detected in Titan's atmosphere by Cassini instruments, with concentrations ranging from sub-ppb in the stratosphere to ppm in the ionosphere. Sustained levels of benzene in the haze formation region could signify that it is an important reactant in the formation of Titan's organic aerosol. To date, there have not been laboratory investigations to assess the influence of benzene on aerosol properties. We report a laboratory study on the chemical composition of organic aerosol formed from C{sub 6}H{sub 6}/CH{sub 4}/N{sub 2} via far ultraviolet irradiation (120-200 nm). The compositional results are compared to those from aerosol generated by a more ''traditional Titan'' mixture of CH{sub 4}/N{sub 2}. Our results show that even a trace amount of C{sub 6}H{sub 6} (10 ppm) has significant impact on the chemical composition and production rates of organic aerosol. There are several pathways by which photolyzed benzene may react to form larger molecules, both with and without the presence of CH{sub 4}, but many of these reaction mechanisms are only beginning to be explored for the conditions at Titan. Continued work investigating the influence of benzene in aerosol growth will advance understanding of this previously unstudied reaction system.

Trainer, Melissa G. [Planetary Environments Laboratory, Code 699, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Sebree, Joshua A. [NASA Postdoctoral Program Fellow, Code 699, Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Heidi Yoon, Y.; Tolbert, Margaret A., E-mail: melissa.trainer@nasa.gov [Cooperative Institute for Research in Environmental Sciences, University of Colorado at Boulder, Box 216 UCB, Boulder, CO 80309 (United States)

2013-03-20

315

Neutron investigations of magnetite-oleic acid-benzene ferrofluids stability with the excess of surfactant  

International Nuclear Information System (INIS)

Magnetite-oleic acid-benzene magnetic fluid with the excess of oleic acid was studied by small-angle neutron scattering. Pure solutions of oleic acid in benzene were also investigated to reveal a possible micelle formation of molecules. It was shown that oleic acid does not form micelles in the investigated range of concentration. the results of experiment indicate that the surfactant excess (smaller than 25% volume fraction) does not lead to any observable aggregation of the magnetic particles. At the same time a bigger attraction between free molecules of surfactant in the ferrofluids in comparison with solutions of oleic acid in benzene is observed. A dramatic breaking of the stability occurs and it leads to the aggregation of magnetic particles if the excess of surfactant is bigger than 25%.

316

Effect of alcohol addition on shock-initiated formation of soot from benzene  

Science.gov (United States)

Soot formation in benzene-methanol and benzene-ethanol argon-diluted mixtures was studied behind reflected shock waves by monitoring the attenuation of an He-Ne laser beam. The experiments were performed at temperatures 1580-2250 K, pressures 2.0-3.0 bar, and total carbon atom concentrations (2.0-2.7) x 10 to the 17th atoms/cu cm. The results obtained indicate that the addition of alcohol suppresses the formation of soot from benzene at all temperatures, and that the reduction in soot yields is increased with the amount of alcohol added. The analysis of the results indicates that the suppression effect is probably due to the oxidation of soot and soot precursors by OH and the removal of hydrogen atoms by alcohol and water molecules.

Frenklach, Michael; Yuan, Tony

1988-01-01

317

Characterization of vanadium-doped mesoporous titania and its adsorption of gaseous benzene  

Energy Technology Data Exchange (ETDEWEB)

A series of vanadium-doped mesoporous titania with different metal contents was synthesized in the study via a sol-gel process with the assistance of a dodecylamine surfactant. The existence of vanadium ions not only suppressed crystallization and sintering but also enhanced the porosity of the mesoporous TiO{sub 2}. Varying the vanadium concentration led to significant changes in the chemical oxidation state of each component. The presence of metal dopants significantly improved the removal efficiency of benzene and the doping the titania with 5 mol% vanadium removed the most benzene, regardless of the adsorption temperature. The adsorption behavior was elucidated by the specific surface area, the interactions between surface hydroxyl groups and the {pi}-electrons of benzene, and the formation of {sigma}-bonding and d-{pi}* back-donation between the adsorbent and organic compounds.

Nguyen-Phan, Thuy-Duong; Song, Myoung Bock; Yun, Hyunran; Kim, Eui Jung; Oh, Eun-Suok [School of Chemical Engineering and Bioengineering, University of Ulsan, Mugeo-dong, Nam-gu, Ulsan 680-749 (Korea, Republic of); Shin, Eun Woo, E-mail: ewshin@mail.ulsan.ac.kr [School of Chemical Engineering and Bioengineering, University of Ulsan, Mugeo-dong, Nam-gu, Ulsan 680-749 (Korea, Republic of)

2011-01-01

318

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

319

46 CFR Appendix D to Subpart C to... - Sampling and Analytical Methods for Benzene Monitoring-Measurement Procedures  

Science.gov (United States)

...prepared by injecting liquid benzene onto the A...by high performance liquid chromatography (HPLC). Detection...analyzed is injected into a liquid chromatograph. 1...detector. 3.2. HPLC Column that will...

2010-10-01

320

Hyperosmotic stress response by strains of bakers' yeasts in high sugar concentration medium.  

Science.gov (United States)

Four strains of bakers' yeast were analysed for their hyperosmotic responses when in media that mimic conditions occurring in bread doughs. Two of the strains produced strong fermentative activity in medium with low osmotic stress, but produced considerably less ethanol in high sucrose concentration medium. Two other strains produced more similar fermentation activities across the range of media tested. The strains that were inhibited by high sucrose concentration were unable to produce significant amounts of glycerol under hyperosmotic conditions. By contrast, the yeasts that were not inhibited significantly by high sucrose produced a considerable amount of glycerol. The strains that produced significant glycerol exhibited efficient expression of the glycerol-3-phosphate dehydrogenase gene GPD1. These novel data on the molecular responses of industrially relevant strains of bakers' yeasts are prerequisite to designing strategies for improving the performance of industrial yeasts in high sugar concentration media. PMID:11068916

Attfield, P V; Kletsas, S

2000-10-01

321

Hydrogen Absorption at Room Temperature in Nanoscale Titanium Benzene Complexes  

OpenAIRE

In this letter we report the first room temperature gravimetric measurements of hydrogen absorption in nanoscale titanium-benzene complexes formed by laser ablation in a benzene atmosphere in a UHV chamber. We are able to obtain a 6% by weight absorption as predicted by recent density functional theory based calculations under the conditions of low benzene pressure (35 milli-torr) and for sub-monolayer samples. For samples synthesized under higher benzene pressures we find a...

Phillips, A. B.; Shivaram, B. S.

2009-01-01

322

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...changes in medicinal drug use, and the appearance...of variations in the susceptibility to benzene morbidity...allergies and some drugs may raise the white...A constellation or pattern of abnormalities in...cell indices, such a pattern is more likely to...

2010-07-01

323

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...15-minute period. 2. Dermal: Eye contact shall be prevented and skin...inhale it, or if it comes in contact with your skin or eyes...exposed to benzene (either by ingestion, inhalation, or skin/eye contact) under emergency...

2010-07-01

324

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...min. 1. Principle of the Method...front of the first section of charcoal and broken open. The glass wool...charcoal in the first (larger) section...area. 7. Calculations. Benzene air...from a number of sources was analyzed...volume. 1. Principle of the...

2010-07-01

325

Stark effect in the benzene dimer.  

Science.gov (United States)

Ab initio calculations of the six-dimensional intermolecular potential have shown the benzene dimer to be an asymmetric top molecule at equilibrium with one benzene moiety forming the "stem" and the other a "tilted cap" in a T-shaped structure. Internal rotation of the cap about its C6 axis is essentially free; the barriers for cap tilting and for internal rotation of the stem about its C6 axis are hindered by successively higher barriers. In previous work we have validated these theoretical results using Fourier transform microwave spectroscopy in conjunction with dynamics calculations. We have also measured the Stark effect, and despite the fact that the equilibrium structure is that of an asymmetric top, the assigned transitions involving K = 0 exhibit a second-order Stark effect whereas those involving K = 1 exhibit a first-order Stark effect. This is typical for a symmetric-top molecule, but anomalous for an asymmetric-top molecule. We use symmetry arguments to explain how this asymmetric-top molecule can have a first-order Stark effect in certain states that have excitation of cap internal rotation. Cap internal rotation is essentially the twisting of the monomers relative to each other about the intermolecular axis, and such torsional motion occurs in other asymmetric top dimers such as benzene-CO and benzene-H2O. These latter dimers will also have levels that exhibit a first-order Stark effect, which we can explain using our symmetry arguments. PMID:24102247

Schnell, Melanie; Bunker, P R; von Helden, Gert; Grabow, Jens-Uwe; Meijer, Gerard; van der Avoird, Ad

2013-12-19

326

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...appropriate to prevent eye contact and limit dermal...provided by the employer at no cost to the...solvents containing greater than 0.1 percent...benzene. (ii) The employer shall assure that...test is equal to or greater than 75 mg phenol/L of urine, the employer shall provide...

2010-07-01

327

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...regarding any new exposure to potential marrow toxins, changes in medicinal drug use, and the...exposure to benzene or any other hematologic toxins. (iii) The employer shall maintain...aprons, etc.) over any parts of your body that could be exposed to liquid...

2010-07-01

328

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

329

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

330

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

Energy Technology Data Exchange (ETDEWEB)

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.

Mickalonis, J.I.

1997-01-01

331

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

Directory of Open Access Journals (Sweden)

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

Zhengjun Zhang

2011-12-01

332

46 CFR 197.565 - Notifying personnel of benzene hazards.  

Science.gov (United States)

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

2010-10-01

333

Electrodeposited ZnO/ Zn Photo catalysts for the Degradation of Benzene-Toluene-Xylene Mixture in Aqueous Phase  

International Nuclear Information System (INIS)

The recognition of the ability of volatile organic compounds, (VOCs) to pollute the ground water is now well documented. VOCs such as benzene, toluene and xylene from the petroleum industries processed water leaked through the underground old piping system into the soils and groundwater during its transportation to the wastewater plant. Photo catalysis have been used as a potential system in the degradation of VOCs in the wastewater. However, the powdered form photo catalysts that were used in various studies are difficult to be separated from the aqueous solution at the end of the treatment. Therefore, the main objective of this research is to prepare the electrodeposited photo catalysts for the degradation of aromatic hydrocarbon mixture, benzene-toluene-xylene (BTX) solution under UV light (354 nm). The concentrations of electrolyte and electrodeposition voltages used to prepare the photo catalysts were studied for their efficiency in the degradation. From the research, ZnO/ Zn prepared in 0.8 M NaOH and under 12 V possessed the best catalytic degradation performance by degrading 32.37 % of BTX in the solution. The ZnO/ Zn photo catalyst was characterized using X-ray Diffraction Techniques (XRD) which illustrated high crystallinity of Zn species and reasonably high amorphous phase of ZnO species. (author)

334

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

OpenAIRE

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

335

Turbulent liquid–liquid dispersion in SMV static mixer at high dispersed phase concentration  

OpenAIRE

The aim of this paper is to investigate the influence of physico-chemical parameters on liquid–liquid dispersion at high dispersed phase concentration in Sulzer SMV™ mixer. Four different oil-in-water systems involving two different surfactants are used in order to evaluate the effect of interfacial tension, densities and viscosities ratio on mean droplets size diameters. Moreover the influence of the dispersed phase concentration on the pressure drop as well as on the droplet size distri...

Lobry, Emeline; Theron, Fe?licie; Gourdon, Christophe; Le Sauze, Nathalie; Xuereb, Catherine; Lasuye, Thierry

2011-01-01

336

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

OpenAIRE

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

Van Duong; Gerardo Diaz

2014-01-01

337

Performance of High-Altitude Platforms Cellular Communications using Hamming-Tapered Concentric Circular Arrays  

OpenAIRE

In this paper, the performance of cellular communications based on the ambitious technology of High-Altitude Platforms (HAPs) is discussed when using tapered concentric circular arrays. The coverage cell will be described and designed with an efficient beamforming technique where the Hamming window is proposed as a tapering function and applied to the uniform concentric circular arrays (UCCA) for sidelobe reduction. Based on establishing some mapping curves, this novel tapering window is opti...

Fahad Alraddady

2014-01-01

338

Human pulmonary responses to experimental inhalation of high concentration fine and ultrafine magnesium oxide particles.  

OpenAIRE

Exposure to air polluted with particles less than 2.5 micron in size is associated epidemiologically with adverse cardiopulmonary health consequences in humans. The goal of this study was to characterize human pulmonary responses to controlled experimental high-dose exposure to fine and ultrafine magnesium oxide particles. We quantified bronchoalveolar lavage (BAL) cell and cytokine concentrations, pulmonary function, and peripheral blood neutrophil concentrations in six healthy volunteers 18...

Kuschner, W. G.; Wong, H.; D Alessandro, A.; Quinlan, P.; Blanc, P. D.

1997-01-01

339

Growth of GaAs ingots with high free electron concentrations  

International Nuclear Information System (INIS)

A horizontal gradient-freeze technique has been developed for growth of GaAs ingots with high free electron concentrations while minimising the crystal defects associated with large quantities of dopant. With Si as dopant satisfactory crystal quality was maintained at carrier concentrations up to 4 x 1018 cm-3. Attempts to extend this range upwards by supplementing the Si doping with other elements showed that the incorporation of one dopant is influenced by the presence of others. Higher carrier concentrations were obtained with Si alone than with Si + Se together. (orig.)

340

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

341

Carrying-out and evaluation of appropriate remedial measures in buildings with high radon concentrations  

International Nuclear Information System (INIS)

The object chosen was an apartment house in Grossschloppen (Fichtelgebirge). Before remedial action started, relatively high radon concentrations, depending on the floor construction (wooden floor, directly laid onto the natural soil), were noted in this building with no basement excavations. By a combination of insulation and soil ventilation methods the original radon concentration of 2600 Bq/m3 could be reduced to 260 Bq/m3 by the factor 10. The remaining concentration-amount has to be attributed to radon trailing from adjacent rooms, which could not be included in the remedial action project. (orig./HP)

342

Switching from photochemical to photothermal mechanism in laser ablation of benzene solutions  

Science.gov (United States)

Nanosecond KrF excimer laser ablation of benzyl chloride, benzyl alcohol, toluene, ethylbenzene, and n-propylbenzene diluted in n-hexane, n-heptane, dichloromethane, and 1,2-dichloroethane was investigated by time-resolved photographic, photoacoustic, and absorbance measurements. Ablation threshold values, Fth, for high concentration solutions (?=250 cm-1, 0.6-1 M) were confirmed to be correlated to photochemical reactivity (?-bond cleavage) of the solute molecules, whereas no distinct relation between Fth and boiling point of solvents was observed. Time-resolved absorbance at the laser wavelength was almost constant during the excitation pulse, which means that the main light-absorbing molecules were fixed to the ground-state solutes. It is considered that this type of ablation is initiated by the photochemical fragmentation. On the contrary, Fth observed in relatively low concentration solutions (?=25 cm-1, 0.06-0.1 M) were about twice higher than those for the high concentration solutions, and had no direct correlation with the photochemical reactivity of the solute molecules. The time-resolved absorbance increased during the excitation pulse, and was ascribed to the fact that benzyl radicals produced by the photodissociation of solute molecules absorbed the excitation photons and converted them into heat through "a cyclic multiphotonic absorption process." Furthermore, morphological aspects observed in nanosecond photography exhibited appreciable differences by varying the solute concentrations. These results clearly mean a concentration-dependent ablation mechanism; the ablation mechanism of the benzene derivative solutions switches from photochemical to photothermal as the solute concentration decreases.

Hatanaka, Koji; Kawao, Mitsushi; Tsuboi, Yasuyuki; Fukumura, Hiroshi; Masuhara, Hiroshi

1997-12-01

343

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

Science.gov (United States)

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

Feuermann, Daniel; Gordon, Jeffrey M.

1998-10-01

344

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

345

Maximum entropy estimation of a Benzene contaminated plume using ecotoxicological assays  

International Nuclear Information System (INIS)

Ecotoxicological bioassays, e.g. based on Danio rerio teratogenicity (DarT) or the acute luminescence inhibition with Vibrio fischeri, could potentially lead to significant benefits for detecting on site contaminations on qualitative or semi-quantitative bases. The aim was to use the observed effects of two ecotoxicological assays for estimating the extent of a Benzene groundwater contamination plume. We used a Maximum Entropy (MaxEnt) method to rebuild a bivariate probability table that links the observed toxicity from the bioassays with Benzene concentrations. Compared with direct mapping of the contamination plume as obtained from groundwater samples, the MaxEnt concentration map exhibits on average slightly higher concentrations though the global pattern is close to it. This suggest MaxEnt is a valuable method to build a relationship between quantitative data, e.g. contaminant concentrations, and more qualitative or indirect measurements, in a spatial mapping framework, which is especially useful when clear quantitative relation is not at hand. - Highlights: ? Ecotoxicological shows significant benefits for detecting on site contaminations. ? MaxEnt to rebuild qualitative link on concentration and ecotoxicological assays. ? MaxEnt shows similar pattern when compared with concentrations map of groundwater. ? MaxEnt is a valuable method especially when quantitative relation is not at hand. - A Maximum Entropy method to rebuild qualitative relationships betweld qualitative relationships between Benzene groundwater concentrations and their ecotoxicological effect.

346

The Mechanism Responsible for High Concentrations of Be-7 in the Near Space  

Science.gov (United States)

In 1990 an unexpectedly high concentration of Be-7 was discovered on the LDEF satellite surface, facing in the RAM direction. The search for an explanation of this high concentration of Be-7 which is in thermal equilibrium in the upper atmosphere, led the researchers to the hypothesis of Be-7 transport by vertical turbulent fluxes from deeper layers in the Earth's atmosphere, where Be-7 is produced as a result of nuclear reactions between solar energetic protons (which penetrated there after a solar flare) and terrestrial atmosphere elements. The experiments carried out during 1995-1999 on 'Resource F1' and 'Cosmos' satellites not only confirmed the existence of high Be-7 concentrations at altitudes of about 200 km, but also permitted to establish correlation between the concentration of Be-7 in the upper atmosphere and flare activity on the Sun. More detailed analysis of the whole set of experimental data on Be-7 measurements at satellite altitudes showed, that the appearance of high Be-7 concentrations in the upper atmosphere of the Earth is a more complicated phenomenon. Two more mechanisms , explaining the observed effect can be indicated. Firstly, the observed concentrations could be associated with direct penetration of energetic Be-7 nuclei, originating in flares, into the terrestrial atmosphere. Calculations show, that in solar cosmic rays the flux of Be-7 nuclei should be maximum in comparison to the fluxes of other Beryllium isotopes. Secondly, the high concentration of Be-7 in the upper atmosphere of the Earth could be explained by solar wind penetration through the polar zones. Theoretical analysis of active processes including flares, occurring in the solar atmosphere, leads to the conclusion, that radioactive Beryllium is constantly present in the solar atmosphere, and, possibly, is the main isotope of solar Beryllium.

Panasyuk, M. I.; Nymmik, R. A.; Kuzhevskii, B. M.; Kulikauskas, V. S.; Zhuravlev, D. A.; Phillips, G. W.; Share, G. H.; King, S. E.; August, R. A.; Tylka, A. J.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

347

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

Science.gov (United States)

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

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

2005-08-01

348

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

International Nuclear Information System (INIS)

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

349

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

350

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

International Nuclear Information System (INIS)

Graphical abstract: H-SiNWs can catalyze hydroxylation of benzene and degradation of methyl red under visible light irradiation. Highlights: ? Hydrogen-terminated silicon nanowires were active photocatalyst in the hydroxylation of benzene under light. ? Hydrogen-terminated silicon nanowires were also effective in the decomposition of methyl red dye. ? The Si/SiOx core-shell structure is the main reason of the obtained high selectivity during the hydroxylation. -- Abstract: Hydrogen-terminated silicon nanowires (H-SiNWs) were used as heterogeneous photocatalysts for the hydroxylation of benzene and for the decomposition of methyl red under visible light irradiation. The above reactions were monitored by GC–MS and UV–Vis spectrophotometry, respectively, which shows 100% selectivity for the transformation of benzene to phenol. A complete decomposition of a 2 × 10?4 M methyl red solution was achieved within 30 min. The high selectivity for the hydroxylation of benzene and the photodecomposition demonstrate the catalytic activity of ultrafine H-SiNWs during nanocatalysis.

351

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

Energy Technology Data Exchange (ETDEWEB)

Graphical abstract: H-SiNWs can catalyze hydroxylation of benzene and degradation of methyl red under visible light irradiation. Highlights: Black-Right-Pointing-Pointer Hydrogen-terminated silicon nanowires were active photocatalyst in the hydroxylation of benzene under light. Black-Right-Pointing-Pointer Hydrogen-terminated silicon nanowires were also effective in the decomposition of methyl red dye. Black-Right-Pointing-Pointer The Si/SiO{sub x} core-shell structure is the main reason of the obtained high selectivity during the hydroxylation. -- Abstract: Hydrogen-terminated silicon nanowires (H-SiNWs) were used as heterogeneous photocatalysts for the hydroxylation of benzene and for the decomposition of methyl red under visible light irradiation. The above reactions were monitored by GC-MS and UV-Vis spectrophotometry, respectively, which shows 100% selectivity for the transformation of benzene to phenol. A complete decomposition of a 2 Multiplication-Sign 10{sup -4} M methyl red solution was achieved within 30 min. The high selectivity for the hydroxylation of benzene and the photodecomposition demonstrate the catalytic activity of ultrafine H-SiNWs during nanocatalysis.

Lian, Suoyuan [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); School of Chemical Engineering and Materials, Dalian Polytechnic University, Dalian 116034 (China); Tsang, Chi Him A. [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Centre of Super Diamond and Advanced Films, City University of Hong Kong, Hong Kong (China); Kang, Zhenhui, E-mail: zhkang@suda.edu.cn [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Liu, Yang, E-mail: yangl@suda.edu.cn [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Wong, Ningbew [Centre of Super Diamond and Advanced Films, City University of Hong Kong, Hong Kong (China); Lee, Shuit-Tong [Institute of Functional Nano and Soft Materials and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Centre of Super Diamond and Advanced Films, City University of Hong Kong, Hong Kong (China)

2011-12-15

352

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

Science.gov (United States)

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

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

2014-07-27

353

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

Science.gov (United States)

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

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

2014-12-01

354

Growth, health, and blood glucose concentrations of calves fed high-glucose or high-fat milk replacers.  

Science.gov (United States)

The influence of age, carbohydrate-fat ratios of milk replacers, and development of ruminal function on growth, health, and blood glucose concentrations were evaluated in calves. Colostrum-fed, 3-day-old Holstein bull calves were fed to 12 wk on one of three dietary treatments: 1) a high carbohydrate, low fat (60.5% glucose, 9.5% lactose, and 3% lard) milk replacer; 2) a low carbohydrate, high fat (23% glucose, 12.5% lactose, and 30% lard) milk replacer; and 3) weaning at 6 wk of age from high-fat replacer to a standard calf starter. The high fat milk replacer was superior to low fat milk replacer for total weight gains and efficiency of feed conversion. Rates of weight gain of starter calves were similar to those of calves fed low fat. Calves fed the diet with low fat had a high incidence of diarrhea, an occasional outbreak of a yeast-related ethanol intoxication syndrome, and high concentrations of glucose in urine. Irrespective of milk replacer composition or development of ruminal function, plasma and whole blood glucose concentrations declined rapidly in the first 6 wk. Corpuscular glucose declined steadily with age in all calves. This age-related decrease of blood glucose concentration of calves seems to be a constitutive phenomenon. PMID:6530490

Wijayasinghe, M S; Smith, N E; Baldwin, R L

1984-12-01

355

Catalytic oxidation of benzene using DBD corona discharges  

International Nuclear Information System (INIS)

Plasma oxidation of benzene (C6H6) in oxygen and nitrogen was investigated using a dielectric barrier discharge (DBD) reactor with or without MnO2 or TiO2 at atmospheric pressure and without external heating except plasma heating. An alternative current power supply was used to generate corona discharges for the plasma oxidation. The energy density was controlled under 200 J/L to keep an increase in gas temperature less than 167 K. C6H6 was oxidized to carbon monoxide (CO) and dioxide (CO2). Typically, the energy efficiency at an energy density of 92 J/L was about 0.052, 0.039, and 0.024 mol/kWh with MnO2, TiO2, and without MnO2 and TiO2, respectively. Benzene oxidation mechanism was mentioned. A comparison on energy efficiency as a function of initial concentration of hydrocarbons, inorganic sulphur compounds, and chloro (fluoro and bromo) carbons was given

356

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)

357

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

358

Mechanism for covalence bond benzene dimers formation: A DFT and MP2 investigation  

Science.gov (United States)

Covalent dimerization mechanisms of benzene were studied by MP2 and three DFT methods with 6-311G(d,p) basis set. All the methods predicted similar meta- and para-cycloaddition mechanisms. MP2 results showed that (1) the activation enthalpies of both the endo- and exo-meta-cycloadditions are about 90 kcal/mol, twice as high as that of para-cycloaddition and (2) further transformation of para-cycloaddition adduct to D2h-(CH)12 and endo-meta-cycloaddition adduct to D3d-(CH)12 need to surmount high enthalpy barriers of 65.02 and 90.78 kcal/mol (relative to two molecules of benzene), respectively. Molecular orbital analysis revealed that meta-cycloaddition of benzene is ground state allowed reaction.

Qin, Yu; Huo, Ruiping; Zhang, Xiang

2014-08-01

359

Threshold photoelectron spectroscopy of benzene up to 26.5 eV  

International Nuclear Information System (INIS)

The threshold photoelectron spectrum of benzene has been recorded up to 26.5 eV photon energy under high-resolution conditions using synchrotron radiation and employing the penetrating-field threshold electron collection method. By means of a direct comparative study with a recent HeI photoelectron spectrum of benzene of equally high resolution, numerous autoionization effects are observed in the formation of the ionic band systems of benzene in the outer valence ionization region in the threshold photoelectron spectrum. The Rydberg states responsible for these effects are identified. Autoionization does not appear to play a role in the formation of the two lowest-energy, inner-valence bands of C6H6+. (author)

360

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

International Nuclear Information System (INIS)

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

361

Impact of highly concentrated contaminants on the quality of oxygen 93 % produced by pressure swing adsorption.  

Science.gov (United States)

A zeolite based pressure swing adsorption (PSA) module designed to produce medicinal oxygen with 90 - 96 % oxygen content was exposed to high input concentrations and high total amounts of CO (17.7 %, 44 mol), CO2 (16.5 %, 23 mol), NO2 (0.98 %, 2 mol), NO (6.2 %, 6 mol) and SO2 (4.2 %, 6 mol). In addition the system was operated with up to 35 % argon in the feed gas. An empirical model was developed to describe the dependence of the oxygen concentration in the product on the oxygen concentration in the input. If the oxygen concentration in the feed gas was reduced below 18 % by dilution, the oxygen concentration in the product fell under the 90 % threshold. Additional effects were observed with NO, NO2 and SO2 which are apparently due to chemical reactions on the adsorbent. These effects consisted of a further decrease in the oxygen concentration measured in the product and could not be reversed by excessive regeneration of the module with air. Under the experimental conditions used, only CO was detected in the product. Appropriate CO monitoring of the input gas is considered a possible remedy for PSA modules in order to ascertain the pharmaceutical quality of the oxygen produced. PMID:25655243

Züchner, K; Pflaum, U B; Meineke, I

2014-01-01

362

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

Science.gov (United States)

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

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

2014-01-01

363

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

DEFF Research Database (Denmark)

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

Elberling, Bo; Kühl, Michael

2013-01-01

364

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

Science.gov (United States)

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

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

2012-10-01

365

Investigating high-concentration monoclonal antibody powder suspension in nonaqueous suspension vehicles for subcutaneous injection.  

Science.gov (United States)

Developing high-concentration monoclonal antibody (mAb) liquid formulations for subcutaneous (s.c.) administration is challenging because increased viscosity makes injection difficult. To overcome this obstacle, we investigated a nonaqueous powder suspension approach. Three IgG1 mAbs were spray dried and suspended at different concentrations in Miglyol® 840, benzyl benzoate, or ethyl lactate. Suspensions were characterized for viscosity, particle size, and syringeability; physical stability was visually inspected. Suspensions generally outperformed liquid solutions for injectability despite higher viscosity at the same mAb concentrations. Powder formulations and properties had little effect on viscosity or injectability. Ethyl lactate suspensions had lowest viscosity (Inverse gas chromatography analysis indicated that the vehicle was the most important factor impacting suspension performance. Ethyl lactate rendered greater heat of sorption (suggesting strong particle-suspension vehicle interaction may reduce particle-particle self-association, leading to low suspension viscosity and glide force) but lacked the physical suspension stability exhibited by the other vehicles. Specific mixtures of ethyl lactate and Miglyol® 840 improved overall performance in high mAb concentration suspensions. This study demonstrated the viability of high mAb concentration (>300 mg/mL) in suspension formulations for s.c. administration. PMID:23001898

Bowen, Mayumi; Armstrong, Nick; Maa, Yuh-Fun

2012-12-01

366

Assessment of the Amur River ecosystem pollution with benzene and its derivatives caused by an accident at the chemical plant in Jilin City, China.  

Science.gov (United States)

Assessment of concentrations of benzene and its derivatives in the Amur water and fish caught in summer and autumn 2006 was carried out after Jilin chemical plant accident (winter 2005) in the People’s Republic of China. Fish sampling of Leiocassis ussuriensis conducted in the Amur River near Khabarovsk identified benzene, toluene, ethylbenzene, isopropylbenzene, xylene reaching to 16, 98.7, 55, 54, and 206 ?g kg?1, respectively. For Hypophthalmichtys molitrix Valenciennes sampled in the lower reaches of the Amur benzene, toluene, ethylbenzene, xylene were found in amounts to 9, 15.4, 16 ?g kg?1, and, benzene and xylene reaching 6 and 16 ?g kg?1 were found in Huso dauricus and benzene and xylene of 2–6 and 13–16 ?g kg?1, respectively, in Acipenser schrenckii. The above toxicants were not detected in the Amur water near the river mouth in autumn 2006. PMID:19572090

Levshina, S I; Efimov, N N; Bazarkin, V N

2009-12-01

367

Kinetics of the uptake of 14C-labeled chlorinated benzenes from soil by plants  

International Nuclear Information System (INIS)

[14C]Benzene, [14C]1,2,4-trichlorobenzene, [14C]pentachlorobenzene, and [14C]hexachlorobenzene were applied to soils in outdoor lysimeters to a 10-cm depth (2 mg/kg dry soil); barley and cress plants were grown for one vegetation period and analyzed after varying time intervals. The bioaccumulation factors (concentration of radioactive substances in plants divided by that in soils) of barley were higher than those of cress, except for hexachlorobenzene. In barley, bioaccumulation factors increased with decreasing chlorine content of the molecules, except for benzene, whereas in cress hexachlorobenzene exhibited the highest bioaccumulation factor. The conversion ratios of chlorinated benzenes (percentage of conversion products based on total radioactivity in plants) were negatively correlated to the chlorine content of the molecules and, in barley, positively correlated with time; in general, they were higher in barley than in cress. The concentration of radioactive substances in the plants, as well as bioaccumulation factors, decreased with time, except for a slight increase in benzene-derived residues in barley after 125 days. This effect is due to growth dilution. The percentage of radioactivity in barley seeds, based on that in the whole plant, was negatively correlated to the chlorine content of the molecule

368

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

Science.gov (United States)

Typha domingensis was exposed to a 100mgL(-1) Cr+100mgL(-1) Ni+100mgL(-1) Zn solution. Metal tolerance and metal accumulation in plant tissues and sediment were studied over time. Although removal rates were different, the three metals were efficiently removed from water. Leaf and root tissues showed high metal concentration. However, the sediment showed the highest accumulation. During the first hours of contact, metals were not only accumulated by sediment and roots but they were also taken up by the leaves in direct contact with the solution. Over time, metals were translocated from roots to leaves and vice versa. Metals caused growth inhibition and a decrease in chlorophyll concentration and affected anatomical parameters. Despite these sub-lethal effects, T. domingensis demonstrated that it could accumulate Cr, Ni and Zn efficiently and survive an accidental dump of high concentrations of contaminants in systems such as natural and constructed wetlands. PMID:24793518

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

2014-07-01

369

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

Science.gov (United States)

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

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

2008-04-01

370

Chlorinated pesticides (2,4-D and DDT) biodegradation at high concentrations using immobilized Pseudomonas fluorescens.  

Science.gov (United States)

Degradation of two chlorinated pesticides (2,4-D and DDT) using a 54-mL glass column packed with tezontle (a low-cost basaltic scoria) was tested. Bacteria were cultured in YPG (yeast, peptone, and glucose) liquid medium at 32 degrees C. The rich medium was pumped during 24 h through the column to inoculate it. Later, the wasted medium was discharged and the pesticide added. Optical densities, TOC, and pesticide concentration were determined. Pesticide removals for 2,4-D (with initial concentration between 100 and 500 mg/L) were about 99%. DDT removal (at initial concentration of up to 150 mg/L) was as high as 55-99%. TOC removals for 2,4-D was in the 36-87% interval, whereas for DDT they were as high as 36-78%. PMID:16047880

Santacruz, Germán; Bandala, Erick R; Torres, Luis G

2005-01-01

371

Au/ZnO nanocomposites: Facile fabrication and enhanced photocatalytic activity for degradation of benzene  

International Nuclear Information System (INIS)

Au nanoparticles supported on highly uniform one-dimensional ZnO nanowires (Au/ZnO hybrids) have been successfully fabricated through a simple wet chemical method, which were first used for photodegradation of gas-phase benzene. Compared with bare ZnO nanowires, the as-prepared Au/ZnO hybrids were found to possess higher photocatalytic activity for degradation of benzene under UV and visible light (degradation efficiencies reach about 56.0% and 33.7% after 24 h under UV and visible light irradiation, respectively). Depending on excitation happening on ZnO semiconductor or on the surface plasmon band of Au, the efficiency and operating mechanism are different. Under UV light irradiation, Au nanoparticles serve as an electron buffer and ZnO nanowires act as the reactive sites for benzene degradation. When visible light is used as the light irradiation source, Au nanoparticles act as the light harvesters and photocatalytic sites alongside of charge-transfer process, simultaneously. -- Graphical abstract: Under visible light irradiation, Au nanoparticles, which are supported on ZnO nanowires, dominate their catalytic properties in gas-phase degradation benzene reaction. Highlights: ? The composites that Au nanoparticles supported on ZnO nanowires were synthesized. ? Au/ZnO composites were firstly used as effective photocatalysts for benzene degradation. ? Two operating mechanisms were proposed depending on excitation wavelength.

372

Au/ZnO nanocomposites: Facile fabrication and enhanced photocatalytic activity for degradation of benzene  

Energy Technology Data Exchange (ETDEWEB)

Au nanoparticles supported on highly uniform one-dimensional ZnO nanowires (Au/ZnO hybrids) have been successfully fabricated through a simple wet chemical method, which were first used for photodegradation of gas-phase benzene. Compared with bare ZnO nanowires, the as-prepared Au/ZnO hybrids were found to possess higher photocatalytic activity for degradation of benzene under UV and visible light (degradation efficiencies reach about 56.0% and 33.7% after 24 h under UV and visible light irradiation, respectively). Depending on excitation happening on ZnO semiconductor or on the surface plasmon band of Au, the efficiency and operating mechanism are different. Under UV light irradiation, Au nanoparticles serve as an electron buffer and ZnO nanowires act as the reactive sites for benzene degradation. When visible light is used as the light irradiation source, Au nanoparticles act as the light harvesters and photocatalytic sites alongside of charge-transfer process, simultaneously. -- Graphical abstract: Under visible light irradiation, Au nanoparticles, which are supported on ZnO nanowires, dominate their catalytic properties in gas-phase degradation benzene reaction. Highlights: Black-Right-Pointing-Pointer The composites that Au nanoparticles supported on ZnO nanowires were synthesized. Black-Right-Pointing-Pointer Au/ZnO composites were firstly used as effective photocatalysts for benzene degradation. Black-Right-Pointing-Pointer Two operating mechanisms were proposed depending on excitation wavelength.

Yu, Hang; Ming, Hai; Zhang, Hengchao; Li, Haitao; Pan, Keming [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Liu, Yang, E-mail: yangl@suda.edu.cn [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Wang, Fang; Gong, Jingjing [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China); Kang, Zhenhui, E-mail: zhkang@suda.edu.cn [Institute of Functional Nano and Soft Materials (FUNSOM) and Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices, Soochow University, Suzhou 215123 (China)

2012-11-15

373

A case study of benzene urinary biomarkers quantification: the comparison between pre- and post-shift samples improves the interpretation of individual biological monitoring data  

Directory of Open Access Journals (Sweden)

Full Text Available Background: Benzene is a common industrial chemical and a component of tobacco smoke and of gasoline. It is widely used as chemical intermediate and is a constituent of crude oil and fuels with a large distribution in the environment owing to vehicles engine emissions. Besides, smoking tobacco is regarded as another major source of environmental benzene exposure. As a consequence, benzene is an ubiquitous pollutant of the outdoor and indoor human environment, and the occupational/environmental exposure concerns a large population. Data from epidemiological studies evidence benzene toxicity to humans. In fact, it is classified as a carcinogen (group A1 by the American Conference of Governmental Industrial Hygienists (ACGIH, suggesting a threshold limit value-time weighted average (TLV-TWA of 0.5ppm.Hence health risks prevention strategies allowing to discriminate between occupational and non-occupational exposure are essential. Objective: Evaluation of occupational exposure to benzene by comparison between urinary biomarkers levels in pre- and post-shift samples in biological monitoring (BM investigations. Methods: The biological monitoring of 14 (smoker and non-smoker workers of a refueling station was performed. Urinary benzene (UB and trans,trans-muconic acid (t,t-MA were used as biological markers. The determinations of UB and t,t-MA were performed by head space-solid phase microextraction followed by gas chromatography/mass spectrometry operating in Selected Ion Monitoring mode and High Performance Liquid Chromatography/UltraViolet detection, respectively. Urinary creatinine levels were also determined.Urine collection was initially performed after work-shift (first BM campaign as suggested by ACGIH. Given difficulties in interpreting data without statistical basis, the urine collection was repeated before and after the work-shift (second BM campaign. Results and Discussion: During the first BM campaign, contrasting results were found. Some workers showed low UB concentrations with respect to t,t-MA ones and vice versa, and although most investigated subjects presented UB and t,t-MA levels below Biological Equivalents (BEs values and ACGIH’s BEI, various exceptions were found, either with exceeding UB or with exceeding t,t-MA levels.According to the ACGIH, the high biomarkers levels found in post-shift urine would have suggested an occupational exposure to benzene. Nevertheless, ACGIH’s BEI are defined on statistical basis and should not be used when individual data are interpreted, in fact results obtained by monitoring post-shift urine only without knowing individual background levels did not facilitate the interpretation of data.As a consequence, the biological monitoring investigation was repeated by collecting urine samples before and after work-shift, and a biomarkers concentration decrement was observed, allowing the discrimination between occupational and non-occupational exposure. Conclusions: The obtained findings suggest that biological monitoring strategies aimed to evaluate the exposure of individuals (single workers to ubiquitous hazardous chemicals, need the measurement of biomarkers concentration both before and after each potential exposure cause, so that confounding factors could be taken into account during data interpretation.

Acampora A

2013-07-01

374

Breeding of wastewater treatment yeasts that accumulate high concentrations of phosphorus  

OpenAIRE

Inorganic phosphate is an essential nutrient. In general, microorganisms take up phosphorus when the extracellular phosphorus concentration is low, but not when it is high. In Saccharomyces cerevisiae, the major phosphate transporters, such as Pho84p, and acid phosphatases (APases), such as Pho5p, are regulated in parallel by the phosphate signal transduction pathway (PHO pathway). We found that PHO mutants expressing PHO84 and PHO5, even under high-P conditions, could take up phosphorus at t...

Watanabe, Takashi; Ozaki, Noriatsu; Iwashita, Kazuhiro; Fujii, Tsutomu; Iefuji, Haruyuki

2008-01-01

375

Operation, modeling and automatic control of complete and partial nitrification of highly concentrated ammonium wastewater  

OpenAIRE

Biological nitrogen removal of high-strength ammonium wastewater was studied in this thesis, particularly, the nitrification process (the oxidation of ammonium to nitrate). This two-step reaction, catalyzed by two kinds of bacteria (AOB and NOB), can suffer serious inhibition problems due to ammonia and nitrous acid when dealing with highly concentrated ammonium wastewater and therefore it requires adequate process control. However, these inhibitions can be used to achieve partial nitrificati...

Jubany Gu?ell, Irene

2007-01-01

376

TREATMENT OF HIGH ETHANOL CONCENTRATION WASTEWATER BY CONSTRUCTED WETLANDS: ENHANCED COD REMOVAL AND BACTERIAL COMMUNITY DYNAMICS  

OpenAIRE

Winery wastewater is characterized by its high chemical oxygen demand (COD), seasonal occurrence and variable composition, including periodic high ethanol concentrations. In addition, winery wastewater may contain insufficient inorganic nutrients for optimal biodegradation of organic constituents. Two pilot-scale constructed wetlands (CWs) were used to treat artificial wastewater: the first was amended with ethanol and the second with ethanol, inorganic nitrogen (N) and phosphorus (P). A numb...

Rodriguez Caballero, Adrian

2011-01-01

377

Prevention of high current concentrations in the nozzle of MHD generators  

Energy Technology Data Exchange (ETDEWEB)

An exact, three-dimensional, analytical description of the current distribution in the nozzle of an MHD channel, under imposed open conditions, is obtained. Strong vorticity of the current flow and high current concentration in the small regions toward the one side of the sidewalls and near the exit of the channel are found.

Kuo, S.; Levi, E.; Schachter, H. (Polytechnic Inst. of New York, Farmingdale (USA))

1985-01-01

378

Prevention of high current concentrations in the nozzle of MHD generators  

International Nuclear Information System (INIS)

An exact, three-dimensional, analytical description of the current distribution in the nozzle of an MHD channel, under imposed open conditions, is obtained. Strong vorticity of the current flow and high current concentration in the small regions toward the one side of the sidewalls and near the exit of the channel are found. (author)

379

Analytical Study of High Concentration PCB Paint at the Heavy Water Components Test Reactor  

Energy Technology Data Exchange (ETDEWEB)

This report provides results of an analytical study of high concentration PCB paint in a shutdown nuclear test reactor located at the US Department of Energy's Savannah River Site (SRS). The study was designed to obtain data relevant for an evaluation of potential hazards associated with the use of and exposure to such paints.

Lowry, N.J.

1998-10-21

380

Analytical Study of High Concentration PCB Paint at the Heavy Water Components Test Reactor  

International Nuclear Information System (INIS)

This report provides results of an analytical study of high concentration PCB paint in a shutdown nuclear test reactor located at the US Department of Energy's Savannah River Site (SRS). The study was designed to obtain data relevant for an evaluation of potential hazards associated with the use of and exposure to such paints

381

Benzene-contaminated groundwaters-transport parameters and isotopic evidence for natural attenuation  

International Nuclear Information System (INIS)

The area of investigation is located on the site of a former hydrogenation plant in Zeitz (Saxonia-Anhalt, Germany). The plant was founded in 1938 to produce gasoline and lubricants originally for the German war industry and was subject of severe bomb strikes in 1944 and 1945 spilling about 250 m3 hydrocarbons into soil. In 1946 it was rebuilt and in the beginning of the 1960s upgraded with a benzene production plant in the eastern part of hydrogenation plant. From 1963 till 1990 the latter produced more than 750,000 t of benzene with maximum production rate in 1979 (79,000 t per year). Leaks and production accidents contaminated groundwater. Contaminations were found in two aquifers. The upper aquifer (I) is a 5-10 m layer of sandy and clayey deposits from the Pleistocene Elster-glacial. The Tertiary aquifer (II) is composed of gravel deposited by an Eocene river, partly overlain by a lignite seam or silt and clay layer of Tertiary age. The prevailing contaminants of aquifer I are BTEX, dominated by high benzene concentrations up to 500 mg L-1. BTEX-concentrations in the aquifer of Tertiary age are considerably lower (100 mg L-1), and benzene is again the dominant pollutant. At three positions, groundwater samples for tritium and 3He analyses were taken from both aquifers trying to match beginning, centre, and end of the contamination plume. Samples exhibit tritium contents of about 10 TU, the groundwater from deepest well 10 TU, the groundwater from deepest well 11.7 TU. Tritiugenic 3He contents are in the upper aquifer between 0 and 3.3 TUequivalent (1 TUequivalent is the 3He content yielded by the decay of 1 TU tritium) corresponding to 3He/tritium ratios of 0.31 and less, whereas in the deeper aquifer tritiugenic 3He was found between 19 and 37 TTUequivalent, i.e. 3He/tritium varies in flow direction from 2.0 to 3.1. In terms of apparent groundwater ages these contents correspond to 3 - 5 years in the upper and 10 - 25 years in the deeper aquifer. In case of samples from the deeper aquifer even increasing apparent ages in flow direction might be evident. The upper aquifer is phreatic, and therefore 3He contents there may be affected by diffusive losses. However, tritium contents in both aquifers indicate apparent ages of less than 15 years. The confinement of the deeper aquifer probably preserves most of tritiugenic 3He. Apparent groundwater ages in Figure 1 indicate a recharge in 1975 or younger. Thus, it is probable that at least in the deeper aquifer the contaminant plume does not 'flow' together with the groundwater. The energy consumption of natural attenuation processes may be covered by 'oxidizers' like nitrate and/or sulphate. Because in contaminated as well as non-contaminated groundwaters of the investigation area the nitrate level is very low, attention was focussed on the isotopic composition of sulphate (?34S) as possible source of energy and on dissolved inorganic carbon (DIC; ?13C) as indicator of totally decomposed hydrocarbons. Fig. 2 shows sulphate content and its ?34S along a flow path in aquifer I, reflecting isotopic enrichment in sulphate due to bacterial reduction. This trend corresponds to a slight decrease of ?13C of DIC from -22.4 per mille to -23.7 per mille confirming the hypothesis of bacterial decomposition of hydrocarbons as natural attenuation process

382

High urine 1-hydroxypyrene glucuronide concentrations in Linxian, China, an area of high risk for squamous oesophageal cancer  

Energy Technology Data Exchange (ETDEWEB)

China has some of the highest oesophageal cancer rates in the world. Recent studies suggest that an association exists between high-level exposure to carcinogenic polycyclic aromatic hydrocarbons (PAHs), such as benzo(a)pyrene (B(a)P), and the development of oesophageal cancer. The inhabitants of this high-risk region extensively use coal and wood for cooking and heating in unvented stoves, and thus may be exposed to PAHs produced during the incomplete combustion of these fuel sources. High levels of B(a)P were recently detected in staple food samples from Linxian and histopathologic changes that may be associated with PAH exposure have also been identified in oesophagectomy specimens from the region. In an effort to determine whether this high-risk population is exposed to high levels of PAHs, voided urines from non-smokers without occupational exposure were collected and analysed using immunoaffinity chromatography and synchronous fluorescence spectroscopy for 1-hydroxypyrene glucuronide, a PAH metabolite and index biomarker for mixed PAH exposure. The median urine 1-hydroxypyrene glucuronide concentration was equivalent to concentrations detected in current smokers. This represents the first report of elevated urine 1-hydroxpyrene glucuronide concentrations in Linxian, and the first biologic confirmation that the inhabitants of this rural, non-industrial, high oesophageal cancer risk region are exposed to carcinogenic PAHs.

Roth, M.J.; Qiao, Y.L.; Rothman, N.; Tangrea, J.A.; Dawsey, S.M.; Wang, G.Q.; Cho, S.H.; Kang, D.; Taylor, P.R.; Strickland, P.T. [NCI, Bethesda, MD (United States). Cancer Prevention Studies Branch

2001-09-01

383

Metatranscriptome of an Anaerobic Benzene-Degrading, Nitrate-Reducing Enrichment Culture Reveals Involvement of Carboxylation in Benzene Ring Activation  

Science.gov (United States)

The enzymes involved in the initial steps of anaerobic benzene catabolism are not known. To try to elucidate this critical step, a metatranscriptomic analysis was conducted to compare the genes transcribed during the metabolism of benzene and benzoate by an anaerobic benzene-degrading, nitrate-reducing enrichment culture. RNA was extracted from the mixed culture and sequenced without prior mRNA enrichment, allowing simultaneous examination of the active community composition and the differential gene expression between the two treatments. Ribosomal and mRNA sequences attributed to a member of the family Peptococcaceae from the order Clostridiales were essentially only detected in the benzene-amended culture samples, implicating this group in the initial catabolism of benzene. Genes similar to each of two subunits of a proposed benzene-carboxylating enzyme were transcribed when the culture was amended with benzene. Anaerobic benzoate degradation genes from strict anaerobes were transcribed only when the culture was amended with benzene. Genes for other benzoate catabolic enzymes and for nitrate respiration were transcribed in both samples, with those attributed to an Azoarcus species being most abundant. These findings indicate that the mineralization of benzene starts with its activation by a strict anaerobe belonging to the Peptococcaceae, involving a carboxylation step to form benzoate. These data confirm the previously hypothesized syntrophic association between a benzene-degrading Peptococcaceae strain and a benzoate-degrading denitrifying Azoarcus strain for the complete catabolism of benzene with nitrate as the terminal electron acceptor. PMID:24795366

Luo, Fei; Gitiafroz, Roya; Devine, Cheryl E.; Gong, Yunchen; Hug, Laura A.; Raskin, Lutgarde

2014-01-01

384

Assessment of pancreatic CT enhancement using a high concentration of contrast material  

Energy Technology Data Exchange (ETDEWEB)

The objective of this study was to evaluate the usefulness of pancreatic enhancement using a high concentration of contrast material in CT. We performed abdominal CT on 125 patients after dividing them at random into five groups with two different concentrations, two different injection rates and three different injection doses: group A: 100 ml, 300 mgI/mL, 3 mL/sec; group B: 2 mL/kg, 300 mgI/mL, 3 mL/sec; group C: 1.5 mL/kg, 370 mgI/mL, 3 mL/sec; group D: 2 mL/kg, 300 mgI/mL, 5 mL/sec; and group E: 1.5 mL/kg, 370 mgI/mL, 5 mL/sec. Among these five groups, the two groups given a concentration of 370 mgI/mL received a dose of 1.5 mL/body weight. The peak enhancement value of the pancreas was significantly greater in group E than in groups A and B. However, no statistically significant differences were found among the other groups. The fast injection rate using the high concentration of contrast medium provided greater enhancement of the pancreas than the slow injection rate using the routine concentration of contrast medium, and pancreatic CT enhancement depended more on the dose of iodine per second than on that of total iodine. (author)

Shinagawa, Masaharu; Uchida, Masafumi; Ishibashi, Masatoshi; Nishimura, Hiroshi; Hayabuchi, Naofumi [Kurume Univ., Fukuoka (Japan). School of Medicine

2003-04-01

385

Biomass concentration and biofilm characteristics in high-performance fluidized-bed biofilm reactors.  

Science.gov (United States)

Two laboratory scale fluidized-bed biofilm reactors (FBBRs) were used to investigate the biomass concentration and the biofilm characteristics in a high performance FBBR used for the denitrification of exceptionally high-nitrate wastewater (1000 mg-N/L). Reported correlations by other workers for predicting the biomass concentration in FBBR were examined for their validity in comparison with the experimental results of this study and the best set of applicable correlations was recommended. The effects of the two main operational parameters, the superficial velocity and nitrogen loading rate on the biomass concentration in the FBBR were also studied. Correlations for the drag coefficient and the expansion index from the literature, together with the biofilm dry density correlation produced from this study were found to produce the best prediction of the FBBR biomass concentration compared to other reported correlations. The average biomass concentration in the FBBR decreased with the increase of the superficial velocity in the range of 45 to 65 m/h at all the applied nitrogen loadings (i.e. 6, 8, 12 and 16 kg-N/m3(bed).d). PMID:16459836

Rabah, F K J; Dahab, M F; Surampalli, R Y

2005-01-01

386

Rapid estimation of concentration of aromatic classes in middistillate fuels by high-performance liquid chromatography  

Science.gov (United States)

An high performance liquid chromatography (HPLC) method to estimate four aromatic classes in middistillate fuels is presented. Average refractive indices are used in a correlation to obtain the concentrations of each of the aromatic classes from HPLC data. The aromatic class concentrations can be obtained in about 15 min when the concentration of the aromatic group is known. Seven fuels with a wide range of compositions were used to test the method. Relative errors in the concentration of the two major aromatic classes were not over 10 percent. Absolute errors of the minor classes were all less than 0.3 percent. The data show that errors in group-type analyses using sulfuric acid derived standards are greater for fuels containing high concentrations of polycyclic aromatics. Corrections are based on the change in refractive index of the aromatic fraction which can occur when sulfuric acid and the fuel react. These corrections improved both the precision and the accuracy of the group-type results.

Otterson, D. A.; Seng, G. T.

1985-01-01

387

High-throughput particle separation and concentration using spiral inertial filtration.  

Science.gov (United States)

A spiral inertial filtration (SIFT) device that is capable of high-throughput (1?ml/min), high-purity particle separation while concentrating recovered target particles by more than an order of magnitude is reported. This device is able to remove large fractions of sample fluid from a microchannel without disruption of concentrated particle streams by taking advantage of particle focusing in inertial spiral microfluidics, which is achieved by balancing inertial lift forces and Dean drag forces. To enable the calculation of channel geometries in the SIFT microsystem for specific concentration factors, an equivalent circuit model was developed and experimentally validated. Large particle concentration factors were then achieved by maintaining either the average fluid velocity or the Dean number throughout the entire length of the channel during the incremental removal of sample fluid. The SIFT device was able to separate MCF7 cells spiked into whole blood from the non-target white blood cells (WBC) with a recovery of nearly 100% while removing 93% of the sample volume, which resulted in a concentration enhancement of the MCF7 cancer cells by a factor of 14. PMID:24738012

Burke, Jeffrey M; Zubajlo, Rebecca E; Smela, Elisabeth; White, Ian M

2014-03-01

388

Application of a regional procedure to assess the risk to fish from high sediment concentrations.  

Science.gov (United States)

Periods of high suspended sediment concentration in rivers can affect the behaviour, health and habitat of freshwater fish. A simple regional model relating daily mean suspended sediment concentration in rivers to flow and percentage of cropped and urban land has been applied to the Lower Swale, UK. The model uses a GIS catchment coverage of hydrological response units (HRUs) of area 5-8 km2, each of which is assumed hydrologically independent and drains to an identified river reach. The sediment delivery properties of each HRU are a function of its land use characteristics determined from existing databases, and hydrological conditions determined from effective rainfall measurements. Daily mean suspended sediment concentrations for each river reach were derived by cumulating simulated HRU flows and sediment loads down successive reaches. A map of the modelled 10% quantile sediment concentrations is presented for both HRUs and river reaches. The map is substantially different from existing erosion risk maps because the delivery model is driven by flow in addition to land use, rather than by soil type. Frequency curves showing the exceedance probability of mean simulated sediment concentrations over 1-6-day durations have been derived using peaks-over-threshold techniques. Maps of the risk of harm to fish, based on the probability of 1- and 4-day sediment concentrations exceeding 80 mg l(-1), are presented. Such maps can be used to assess the impact of sediment on fish and for setting appropriate river water quality objectives. PMID:14499550

Watts, Carol D; Naden, Pamela S; Cooper, David M; Gannon, Beate

2003-10-01

389

Off-pathway aggregation can inhibit fibrillation at high protein concentrations  

DEFF Research Database (Denmark)

Ribosomal protein S6 fibrillates readily at slightly elevated temperatures and acidic pH. We find that S6 fibrillation is retarded rather than favored when the protein concentration is increased above a threshold concentration of around 3.5mg/mL. We name this threshold concentration C(FR), the concentration at which fibrillation is retarded. Our data are consistent with a model in which this inhibition is due to the formation of an off-pathway oligomeric species with native-like secondary structure. The oligomeric species dominates at high protein concentrations but exists in dynamic equilibrium with the monomer so that seeding with fibrils can overrule oligomer formation and favors fibrillation under C(FR) conditions. Thus, fibrillation competes with formation of off-pathway oligomers, probably due to a monomeric conversion step that is required to commit the protein to the fibrillation pathway. The S6 oligomer is resistant to pepsin digestion. We also report that S6 forms different types of fibrils dependent on protein concentration. Our observations highlight the multitude of conformational states available to proteins under destabilizing conditions.

Deva, Taru; Lorenzen, Nikolai

2013-01-01

390

Personal exposure of children and adults to airborne benzene in four French cities  

Science.gov (United States)

Atmospheric concentrations of and personal exposure to benzene have been measured in four French metropolitan areas for 210 subjects over two seasons. Half of the volunteers were 6-13-year-old children. The adult subjects were non-smokers, not occupationally exposed and they live and work in the monitored areas. Measurements were performed using diffusive samplers followed by GC-FID analysis. The average values for ambient air concentrations (?g m -3) were: Rouen: 1.5; Île de France (Paris area): 1.6; Grenoble: 2.3 and Strasbourg: 2.6, showing that benzene concentrations in the ambient air of the four cities satisfy the requirements of the European Directive 2000/69EC of the European Parliament which stipulates a limit value of 5 ?g m -3. However, the 48 h exposures measured were found to be between 2.7 and 3.5 times higher than ambient air concentrations. As a consequence, 60% of the subjects investigated, including children, were exposed to concentrations higher than the ambient air limit value. This work confirms that air monitoring data collected by fixed stations should be used with caution when assessing population exposure to benzene, especially given the influence of indoor sources and other polluted microenvironments where people spend part of their time.

Gonzalez-Flesca, Norbert; Nerriere, Eléna; Leclerc, Nathalie; Le Meur, Sébastien; Marfaing, Hélène; Hautemanière, Alexis; Zmirou-Navier, Denis

391

Irrigation with Groundwater Containing Relatively High Concentrations of Radium: Effect on Soil  

International Nuclear Information System (INIS)

Naturally occurring radium isotopes at relatively high concentrations are found in groundwater in the southern part of Israel in two main aquifers of the Negev and the Arava Valley: the Nubean Sandstone (Kurnub group) and the Lower Cretaceous (Judea group)(1). Radium is being transferred from the host rock into the aquifer by geochemical processes and it is commonly found in the groundwater as three isotopes: Ra (half-life of 5.75y), Ra (half-life of 1600y) and 224Ra (half-life of 3.66d). High radium concentrations may play a key role in the potential exploitation and utilization of groundwater for drinking water as well as for agricultural purposes. Radionuclides of natural origin, including radium, are present in all foodstuffs at varying degrees. In essence, the doses from natural radionuclides are not worthy to control since the concentrations are mostly low and the resources required to control exposure would be out of proportion to the benefits achieved for health. Nevertheless, in prone areas, where radium concentrations in the ground water are significantly higher than drinking water standards, it is recommended to investigate the effect of using such water sources for agricultural purposes. Irrigation with water containing high radium concentrations may imply that the radium could find its way into the food chain having been integrated into the plant with the water(2'3). Water from the Shizafon 1 and 11 drillings is intended to be used for irrigatillings is intended to be used for irrigation. The Shizafon drillings are characterized by a radium concentration exceeding the current Israeli drinking water standards by ca. 300%. The current study investigates the influence of drip irrigation with radium-containing water on the culture medium

392

A high plasma concentration of TNF-alpha is associated with dementia in centenarians  

DEFF Research Database (Denmark)

Background Inflammatory mechanisms and immune activation have been hypothesized to play a role in the pathogenesis of age-associated diseases such as dementia and atherosclerosis. The purpose of this study was to evaluate the plasma concentration of tumor necrosis factor (TNF)-alpha in a large cohort of centenarians and to look for its possible associations with cognitive function, atherosclerosis, and general health status. Furthermore, we investigated whether the concentration of TNF-alpha was correlated with the blood concentration of leucocyte subsets or the plasma concentrations of interleukin (IL)-6, soluble TNF receptor II (sTNFR-II) (75 kDa) and C-reactive protein (CRP). Methods. Plasma TNF-alpha was measured by ELISA in 126 centenarians, 45 subjects aged 81 years, 23 subjects aged 55-65 years, and 38 subjects aged 18-30 years. Atherosclerosis was evaluated by the ankle-brachial blood pressure index, and general health status was evaluated by the body mass index and the number of diagnoses present Results. The concentration of TNF-alpha was significantly increased in 126 centenarians compared to younger control groups, and a high concentration of TNF-alpha was associated with both Alzheimer's disease and generalized atherosclerosis in the centenarians. The concentration of TNF-alpha was positively correlated with the concentrations of plasma IL-6, sTNFR-II, and CRP. No associations were found with increased leucocyte subsets or the body mass index. Conclusion. This study demonstrates that, even in apparently healthy subjects, age-associated immune activation indicated by raised levels of pro-inflammatory cytokines may reflect age-associated pathological processes that develop over decades.

Bruunsgaard, H.; Andersen-Ranberg, K.

1999-01-01

393

High-concentration collection and remote delivery of sunlight with fiber optic minidishes  

Science.gov (United States)

A new approach to the efficient collection and remote delivery of concentrated solar energy is proposed. The system's building block is a miniature (e.g., 0.2 m diameter) dish which concentrates sunlight into a single optical fiber. A number of mini-dishes comprise a module from which the optical fibers transport bundled power to a remote receiver. A second-stage nonimaging concentrator can boost flux levels to those approaching the thermodynamic limit and can be performed either in each individual dish or collectively in one or more larger devices at the entrance to the remote receiver. There are substantial advantages in efficiency, compactness, reduced mechanical loads, and ease of fabrication and installation relative to conventional solar designs. The design exploits the availability of low- attenuation optical fibers of high numerical aperture, as well as the practical advantages of mass producing highly accurate very small parabolic dishes. Designs for maximum efficiency attaining collection efficiencies as high as 80%, and maximum-concentration designs realizing flux levels of 30,000 suns, are achievable.

Feuermann, Daniel; Gordon, Jeffrey M.

1999-10-01

394

The osmotic pressure of highly concentrated monoclonal antibody solutions: effect of solution conditions.  

Science.gov (United States)

The behavior of monoclonal antibodies at high concentrations is important in downstream processing, drug formulation, and drug delivery. The objective of this study was to evaluate the osmotic pressure of a highly purified monoclonal antibody at concentrations up to 250 g/L over a range of pH and ionic strength, and in the presence of specific excipients, using membrane osmometry. Independent measurements of the second virial coefficient were obtained using self-interaction chromatography, and the net protein charge was evaluated using electrophoretic light scattering. The osmotic pressure at pH 5 and low ionic strength was >50 kPa for antibody concentrations above 200 g/L. The second virial coefficients determined from the oncotic pressure (after subtracting the Donnan contribution) were in good qualitative agreement with those determined by self-interaction chromatography. The second virial coefficient decreased with increasing ionic strength and increasing pH due to the reduction in intermolecular electrostatic repulsion. The third virial coefficient was negative under all conditions, suggesting that multi-body interactions in this system are attractive. The virial coefficients were essentially unaffected by addition of sucrose or proline. These results have important implications for the analysis of protein-protein interactions in downstream processing at high protein concentrations. PMID:23996891

Binabaji, Elaheh; Rao, Suma; Zydney, Andrew L

2014-03-01

395

Reduced antineoplastic activity in mice of cisplatin administered with high salt concentration in the vehicle.  

Science.gov (United States)

The effect of high NaCl concentration in the vehicle on the toxic and antineoplastic activities of cisplatin [cis-dichloro-diammineplatinum(II)] (CDDP) was reinvestigated in mice. The toxicity, as measured by the survival of mice given CDDP iv, was reduced by 50-60% when the NaCl concentration in the vehicle was raised from 0.9 to 4%. In ascitic P388 leukemia the antineoplastic activity of CDDP given ip was not reduced significantly. However, in all other systems studied the antitumor activity was reduced when the CDDP was dissolved in high NaCl solution. The tumor models studied included systemic P388 and L1210 leukemias, Lewis lung carcinoma, and 5 human tumor xenografts. The human tumors were studied by the subrenal capsule assay. In the case of a malignant melanoma and a malignant fibrous histiocytoma, the effect also was demonstrated in the subcutaneous nude mouse model. In one of the malignant melanomas a 50% increase in the CDDP dose did not compensate for the reduced antitumor activity caused by the high NaCl concentration in the vehicle. These results, which stand in contrast to current views, question the experimental basis for the use of high-NaCl vehicles in the "high-dose" CDDP regimens. PMID:6590919

Aamdal, S; Fodstad, O; Kaalhus, O; Pihl, A

1984-09-01

396

Vasopressin activates Akt/mTOR pathway in smooth muscle cells cultured in high glucose concentration  

Energy Technology Data Exchange (ETDEWEB)

Highlights: •AVP induces mTOR phosphorylation in A-10 cells cultured in high glucose concentration. •The mTOR phosphorylation is mediated by the PI3K/Akt pathway activation. •The AVP-induced mTOR phosphorylation inhibited autophagy and stimulated cell proliferation. -- Abstract: Mammalian target of rapamycin (mTOR) complex is a key regulator of autophagy, cell growth and proliferation. Here, we studied the effects of arginine vasopressin (AVP) on mTOR activation in vascular smooth muscle cells cultured in high glucose concentration. AVP induced the mTOR phosphorylation in A-10 cells grown in high glucose, in contrast to cells cultured in normal glucose; wherein, only basal phosphorylation was observed. The AVP-induced mTOR phosphorylation was inhibited by a PI3K inhibitor. Moreover, the AVP-induced mTOR activation inhibited autophagy and increased thymidine incorporation in cells grown in high glucose. This increase was abolished by rapamycin which inhibits the mTORC1 complex formation. Our results suggest that AVP stimulates mTOR phosphorylation by activating the PI3K/Akt signaling pathway and, subsequently, inhibits autophagy and raises cell proliferation in A-10 cells maintained in high glucose concentration.

Montes, Daniela K.; Brenet, Marianne; Muñoz, Vanessa C.; Burgos, Patricia V.; Villanueva, Carolina I. [Department of Physiology, Universidad Austral de Chile, Valdivia 509-9200 (Chile); Figueroa, Carlos D. [Department of Anatomy, Histology and Pathology, Universidad Austral de Chile, Valdivia 509-9200 (Chile); González, Carlos B., E-mail: cbgonzal@uach.cl [Department of Physiology, Universidad Austral de Chile, Valdivia 509-9200 (Chile); Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555 (United States)

2013-11-29

397

Cost-benefit analysis applied to building materials with comparatively high natural radionuclide concentration  

International Nuclear Information System (INIS)

An attempt is made to apply cost benefit analysis to justify the replacement of building materials that have comparatively high natural radionuclide concentrations with those lower concentrations, including the analysis of man-rem monetary equivalent (i.e. the maximum expenditure which the society can afford to spend on 1 man-rem population dose reduction), assessments. Values adopted for man-rem equivalents range from Pound10 to Pound250 (7.5 to 188 roubles). The present calculations suggest that Pound10 is much more reasonable than Pound250. (author)

398

Enhancement of cellulose degradation by Ruminococcus albus at high cellulose concentration  

Energy Technology Data Exchange (ETDEWEB)

One of the cellulolytic rumen anaerobes, Ruminococcus albus, was found to be cultivatable in a rumen medium containing high concentration of ball-milled cellulose (BMC) by occasional addition of ammonium sulfate to the medium. The degradation rate of BMC by the microorganism increased in proportion to the BMC concentration. Eighty grams of BMC per l of the medium were completely solubilized within 3 days, suggesting that the degradation rate was increased 5 times over the maximum rate obtained when 15 g of BMC was fed into 1 l of the medium. This method is thought to be a kind of immobilized living cell cultivation.

Ohmiya, K.; Nokura, K.; Shimizu, S.

1983-01-01

399

Paradoxical Effect of Caspofungin: Reduced Activity against Candida albicans at High Drug Concentrations  

OpenAIRE

Resistance problems with caspofungin, an echinocandin inhibitor of fungal cell wall glucan synthesis, have been rare. We noted paradoxical turbid growth of Candida albicans isolates in broth in some high (supra-MIC) concentrations. Among isolates submitted for susceptibility testing and screened at drug concentrations up to 12.5 ?g/ml, the frequency was 16%. Analysis of the turbid growth indicated slowing of growth in the presence of drug but with numbers of CFU up to 72% those of drug-free ...

Stevens, David A.; Espiritu, Marife; Parmar, Rachana

2004-01-01

400

Concentration- and pH-dependence of highly alkaline sodium silicate solutions.  

Science.gov (United States)

In this study two routes for the gelation of water glass have been investigated; the destabilization by a change in pH and by an increase in concentration through evaporation. Both methods produce optically transparent, highly viscous, homogeneous solutions. The structure and dynamics of the solutions along the two routes have been investigated with dynamic light scattering, (29)Si-Nuclear Magnetic Resonance spectroscopy, viscosity measurements and infrared spectroscopy. We find that the two routes are fundamentally different. Increasing the concentration of the sodium silicate system leaves the silica speciation apparently unchanged. Lowering the pH leads to condensation reactions, thus a change in the silica speciation. PMID:21272893

Nordström, Jonas; Nilsson, Erik; Jarvol, Patrik; Nayeri, Moheb; Palmqvist, Anders; Bergenholtz, Johan; Matic, Aleksandar

2011-04-01

401

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

International Nuclear Information System (INIS)

Background: Environmental tobacco smoke (ETS) is one of the most important sources for indoor air pollution and a substantial threat to human health, but data on the concentrations of the trace metals cerium (Ce) and lanthanum (La) in context with ETS exposure are scarce. Therefore the aim of our study was to quantify Ce and La concentrations in indoor air with high ETS load. Methods: In two subsequent investigations Ce, La and cadmium (Cd) in 3 smokers' (11 samples) and 7 non-smokers' (28 samples) households as well as in 28 hospitality venues in Southern Germany were analysed. Active sampling of indoor air was conducted continuously for seven days in every season in the smokers' and non-smokers' residences, and for 4 h during the main visiting hours in the hospitality venues (restaurants, pubs, and discotheques). Results: In terms of residences median levels of Cd were 0.1 ng/m3 for non-smokers' and 0.8 ng/m3 for smokers' households. Median concentrations of Ce were 0.4 ng/m3 and 9.6 ng/m3, and median concentrations of La were 0.2 ng/m3 and 5.9 ng/m3 for non-smokers' and for smokers' households, respectively. In the different types of hospitality venues median levels ranged from 2.6 to 9.7 ng/m3 for Cd, from 18.5 to 50.0 ng/m3 for Ce and from 10.6 to 23.0 ng/m3 for La with highest median levels in discotheques. Conclusions: The high concentrations of Ce and La found in high concentrations of Ce and La found in ETS enriched indoor air of smokers' households and hospitality venues are an important finding as Ce and La are associated with adverse health effects and data on this issue are scarce. Further research on their toxicological, human and public health consequences is urgently required. - Highlights: ? We quantified cer, lanthanum and cadmium concentrations in indoor air. ? Cer and lanthanum concentrations were high in tobacco smoke enriched locations. ? Both elements can be considered as good markers for indoor air quality.

402

Protein-poly(amino acid) complex precipitation for high-concentration protein formulation.  

Science.gov (United States)

A method for concentration of protein solutions is required for high-dosage protein formulation. Here, we present a precipitation-redissolution method by poly(amino acid) for proteins, including therapeutic enzymes, antibodies, and hormones. The proteins were fully precipitated by the addition of poly-L-lysine or poly-L-glutamic acid at low ionic strength, after which precipitate was dissolved at physiological ionic strength. The activities and secondary structures of redissolved proteins, especially antibodies, were almost identical to the native state. The precipitation-redissolution method is a simple and rapid technique for concentration of protein formulations. PMID:24931504

Kurinomaru, Takaaki; Maruyama, Takuya; Izaki, Shunsuke; Handa, Kenji; Kimoto, Tomoaki; Shiraki, Kentaro

2014-08-01

403

RADIOACTIVE HIGH LEVEL WASTE TANK PITTING PREDICTIONS: AN INVESTIGATION INTO CRITICAL SOLUTION CONCENTRATIONS  

Energy Technology Data Exchange (ETDEWEB)

A series of cyclic potentiodynamic polarization tests was performed on samples of ASTM A537 carbon steel in support of a probability-based approach to evaluate the effect of chloride and sulfate on corrosion the steel?s susceptibility to pitting corrosion. Testing solutions were chosen to systemically evaluate the influence of the secondary aggressive species, chloride, and sulfate, in the nitrate based, high-level wastes. The results suggest that evaluating the combined effect of all aggressive species, nitrate, chloride, and sulfate, provides a consistent response for determining corrosion susceptibility. The results of this work emphasize the importance for not only nitrate concentration limits, but also chloride and sulfate concentration limits.

Hoffman, E.

2012-11-08

404

The Effects of High Concentrations of Vitamin C on Cancer Cells  

Directory of Open Access Journals (Sweden)

Full Text Available The effect of high doses of vitamin C for the treatment of cancer has been controversial. Our previous studies, and studies by others, have reported that vitamin C at concentrations of 0.25–1.0 mM induced a dose- and time-dependent inhibition of proliferation in acute myeloid leukemia (AML cell lines and in leukemic cells from peripheral blood specimens obtained from patients with AML. Treatment of cells with high doses of vitamin C resulted in an immediate increase in intracellular total glutathione content and glutathione-S transferase activity that was accompanied by the uptake of cysteine. These results suggest a new role for high concentrations of vitamin C in modulation of intracellular sulfur containing compounds, such as glutathione and cysteine. This review, discussing biochemical pharmacologic studies, including pharmacogenomic and pharmacoproteomic studies, presents the different pharmacological effects of vitamin C currently under investigation.

Seyeon Park

2013-09-01

405

High Er3+ concentration low refractive index fluorophosphate glass for evanescent wave optical amplifiers  

International Nuclear Information System (INIS)

This is about the first reported laser glass with very low nD, high Er3+ concentration and no quenching. In this work, a series of high Er3+ concentration (10.6-12.2x1020 ions/cm3), low refractive index (n1550<1.47) and relatively high fluorescence lifetime (6.8-12.6 ms) fluorophosphate glasses were made. A cw-pumping evanescent wave optical amplifier experiment was performed with it, and a relative gain of around 2 dB at 1550 nm wavelength was achieved while the noise level was almost unchanged. To our knowledge, this is the first successful relative gain in evanescent wave optical amplifiers (EWOA) demonstrated with cw pumping. It is a valuable study of specially designed fluorophosphate glass suitable for EWOA communication experiment

406

Phenomenon of energy concentration in super-high energy ?-hadron families  

International Nuclear Information System (INIS)

The family events observed with iron emulsion chambers at Mt. Kanbala are analyzed and compared with the simulations by the COSMOS code and CORSIKA code respectively. A detailed study on the production of super-high energy ?-hadron families with energy concentration behavior is carried out. The preliminary conclusions are: 1) the energy concentration behavior of super-high energy ?-hadron families is the external embodiment of high energy central shower clusters contained in the families. 2) the mean lateral spread of these clusters is about 0.37 cm. 3) the frequency of this phenomenon appeared under the conditions of R?10 mm and X10?90% is (20.5 +- 3.1)%. 4) compared to the COSMOS code based on the phenomenological multi-cluster model, the simulation by the CORSIKA code that adopts SIBYLL model is closer to the analytical results of experiment

407

The role of silicon interstitials in the deactivation and reactivation of high concentration boron profiles  

International Nuclear Information System (INIS)

Boron cluster formation and dissolution in high concentration B profiles and the role of Si interstitials in these processes are analyzed by kinetic non-lattice Monte Carlo atomistic simulations. For this purpose, we use theoretical structures as simplifications of boron implants into preamorphized Si, followed by low-temperature solid phase epitaxial (SPE) regrowth or laser thermal annealing process. We observe that in the presence of high B concentrations (above 1020 cm-3), significant deactivation occurs during high temperature anneal, even in the presence of only equilibrium Si interstitials. The presence of additional Si interstitials from an end of range (EOR) damage region accelerates the deactivation process and makes B deactivation slightly higher. We show that B deactivation and reactivation processes can be clearly correlated to the evolution of Si interstitial defects at the EOR. The minimum level of activation occurs when the Si interstitial defects at EOR dissolve or form very stable defects