WorldWideScience

Sample records for high benzene concentrations

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

    Directory of Open Access Journals (Sweden)

    Ali Karimi

    2013-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Karimi Ali

    2013-01-01

    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.

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

    OpenAIRE

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

    2013-01-01

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

  4. Benzene vapor concentrations during a simulated crude oil spill

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2013-04-01

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

  6. Assessment and influence of operational parameters on the TiO2 photocatalytic degradation of sodium benzene sulfonate under highly concentrated solar light illumination

    International Nuclear Information System (INIS)

    Sodium benzene sulfonate (BS) was decomposed in aqueous TiO2 dispersions under highly concentrated solar light illumination to examine the photocatalytic characteristics of a parabolic round concentrator (PRC) reactor to degrade the pollutant without visible light absorption. The effects of such operational parameters as initial concentration, volume of the aqueous BS solution, oxygen purging, and TiO2 loading on the kinetics of decomposition of BS were investigated. An effective photodegradation necessitates a suitable combination of initial volume and concentration of BS solution. Relative to atmospheric air, oxygen purging significantly accelerates the degradation process at high initial concentrations of BS (0.40 mM or 1.0 mM). Optimal TiO2 loading was 9 gl -1, greater than previously reported. Elimination of TOC (total organic carbon) followed pseudo first-order kinetics in the initial stages of the photodegradation process. The relative photonic efficiency for the photodegradation of BS is ?rel=1.0. (Author)

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

    DEFF Research Database (Denmark)

    Palmgren, F.; Berkowicz, R.

    2000-01-01

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

  8. Benzene

    Science.gov (United States)

    Benzene is a colorless or light-yellow liquid chemical at room temperature. It is used primarily as a solvent in the chemical and pharmaceutical industries, as a starting material and an intermediate in the synthesis of numerous chemicals, and in gasoline. Benzene is produced by both natural and man-made processes. It is a natural component of crude oil, which is the main source of benzene produced today. Other natural sources include gas emissions from volcanoes and forest fires.

  9. 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.)

  10. PREFRACTIONATION OF HIGH BENZENE PRECURSORS’ FEED FOR HYBRID REFORMER UNIT

    OpenAIRE

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

    2008-01-01

    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...

  11. PREFRACTIONATION OF HIGH BENZENE PRECURSORS’ FEED FOR HYBRID REFORMER UNIT

    Directory of Open Access Journals (Sweden)

    K. Kirilov

    2008-03-01

    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.

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

    DEFF Research Database (Denmark)

    Klotz, B; Volkamer, R

    2002-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-12-15

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

  14. 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

  15. Possible Causes of Decreasing Benzene Concentrations in an Oil-Contaminated Aquifer

    Science.gov (United States)

    Drennan, D.; Bekins, B. A.; Warren, E.; Baedecker, M. J.; Eganhouse, R. P.

    2010-12-01

    Crude oil contamination from a 1979 oil spill near Bemidji, Minnesota resulted in a subsurface oil body and a dissolved hydrocarbon plume in the groundwater. Benzene concentrations in the plume adjacent to the oil decreased from nearly 5 mg/L in 1993 to less than 3 mg/L in 2007. Benzene depletion within the plume and oil body was investigated with a microcosm study and analyses of the benzene content remaining in the oil. To test if the methanogenic microbial consortium adjacent to the oil is capable of degrading benzene, eight anaerobic microcosms were constructed with sediment from a methanogenic area of the plume that has been exposed to benzene. Microcosms were constructed in 120 mL serum bottles containing 60 g of anaerobic sediment, 20 mL pre-reduced mineral salts solution, and spiked with benzene to attain a target concentration of 2 mg/L. The methanogenic inhibitor, 2-bromoethanesulfonate (BES), was added to four bottles to achieve a concentration of 13.5 g/L. One bottle containing BES and another not containing BES were autoclaved. Over a year the average aqueous benzene concentrations decreased 2.9±0.4 ?g/L-day in the inhibited microcosms, 3.1±0.3 ?g/L-day in the uninhibited microcosms, and 2.1±0.5 ?g/L-day in the autoclaved microcosms. Although the linear regressions slopes differed, the difference in the rates between the BES inhibited, uninhibited, and autoclaved treatments is not statistically significant with the existing data (p=0.19). Headspace analyses for methane conducted after 392 days showed concentrations in the uninhibited microcosms were about 40 times greater than the inhibited microcosms and autoclaved controls. The methane concentrations in the inhibited microcosm were lower than dissolved methane originally present in the pore water of the added sediment. Oil samples bailed from four wells in the oil body were analyzed for benzene concentrations and normalized to the benzene content of an archived sample representative of the original spilled oil. Relative benzene content in the four oil samples ranged from 7-61% of the original oil. The benzene percentage was compared with pore space oil saturations determined from sediment cores. Results show that benzene depletion is linearly correlated (R2 =0.93) with oil saturations over a range of saturations from 8 to 62%. The linear relation suggests that the relative permeability for water flowing past the oil controls the benzene depletion. That is, the more oily sediments had lower permeabilities resulting in less dissolution and higher benzene concentrations relative to less oily sediments. The results of the oil analyses and microcosm experiment suggest dissolution, not methanogenic biodegradation, is the main control on the decrease of benzene concentration in the oil body and the adjacent plume.

  16. High-efficiency plasma catalytic removal of dilute benzene from air

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  18. 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)

  19. Theoretical study of possible benzene dimerizations under high-pressure conditions

    International Nuclear Information System (INIS)

    We offer a theoretical explanation of the rate processes observed macroscopically in materials composed of aromatic ring structures subjected to high pressure. Earlier workers have made qualitative suggestions that the origin of these processes may be due to interring pi bonding. By making quantum-mechanical calculations on a simple special case of such systems (i.e., two interacting benzene rings), we attempt to produce a quantitative microscopic foundation for the suggestions. We briefly review earlier experimental and theoretical work on the subject and thereby motivate the working hypotheses used in the calculations. The principal hypothesis is that by studying restricted parts of the two benzene-ring energy hypersurface, we can learn something about the pressure-induced rate process for all the arene structures. By use of the modified-neglect-of-diatomic-differential-overlap (MNDO) method and the generalized valence bond ''perfect-pairing'' (GVP--PP) method supplemented by configuration interaction, we found two metastable ground electronic state dimers of benzene; we suggest that one of these is the source of the observed rate process seen in benzene at high pressure. Further, we suggest that analogous dimerizations are responsible for the rate processes seen in larger arene materials subjected to very high pressures. The detailed geometries and energies of both benzene dimers are given. Suggestions for experimentally testing whether the proposed explanation is sting whether the proposed explanation is correct are given

  20. Indicators of benzene emissions and exposure in Bangkok street

    International Nuclear Information System (INIS)

    Ambient benzene measurements were conducted for the first time at four air monitoring sites in the Bangkok metropolitan region (BMR), from January to December 2001. Analytical results show that the mean benzene concentrations range from 42.4 ?g/m3 at the Din Daeng urban site to 15.1 ?g/m3 at the Chaeng Wattana suburban site. The monitoring results show that at a larger distance from the roadside or a higher level from the street surface, the level of benzene decreases. Analysis of the ambient benzene concentrations was carried out with reference to meteorological influences and traffic density. In traffic analysis, the combined effects of street topography and traffic flows established high impact on the overall benzene concentration in Bangkok. Statistical analysis shows good correlations of blood benzene levels and trans, trans-muconic acid with ambient benzene and demonstrated substantial exposure from traffic

  1. Formation of high molecular weight products from benzene during boundary lubrication

    Science.gov (United States)

    Morales, W.

    1985-01-01

    High molecular weight products were detected on the wear track of an iron disk at the end of a sliding friction and wear test using benzene as a lubricant. Size exclusion chromagography in conjunction with UV analysis gave evidence that the high molecular weight products are polyphenyl ether type substances. Organic electrochemistry was used to elucidate the possible surface reaction mechanisms.

  2. Isopropylation of benzene with 2-chloropropane on high-temperature chlorine-treated alumina catalyst; Koon enso shori arumina shokubaijo deno benzen no 2-kuroroporopan niyoru arukiruka hanno

    Energy Technology Data Exchange (ETDEWEB)

    Imanishi, Kazuhiro; Saeki, Takayuki; Sawada, Goro; Ayame, Akimi [Muroran Institute of Technology, Hokkaido (Japan)

    1999-09-01

    On the alumina catalyst, AmLSA, treated dry chlorine at 573-1173 K, isopropylation of benzene with 2-chloropropane (2CP) was carried out at 273 K using a semi-batch reactor in which the catalyst was suspended in benzene. AmLSA catalysts showed high activities for isopropylation of benzene and isopropylbenzene. The products were isopropylbenzene (IPB), ortho- meta-, and para-di-isopropylbenzenes (di-IPB), and 1,2,4- and 1,3,5-tri-isopropylbenzenes (tri-IPB) Formation of tetra-isopropylbenzenes was negligibly small. A typical product composition at 2CP conversion 100% was 76, 19, and 5% for IPB, di-IPB, and tri-IPB respectively, while for isopropylation of IPB, di-IPB and tri-IPB were 82 and 18%, respectively. Pyridine absorption completely poisoned the AmLSA catalyst and even after outgassing at 873 K, the original activity was not restored. Since the reactions were completely stopped stopped by removal of the catalyst from the reaction system, it was concluded that no active species was not dissolved into the organic phase. From the above results and from both results of alkylation of benzene with 1-chloropropane (ICP) and isopropylation using an aluminium trichloride catalyst, it is explainable that reactions on AmLSA catalysts proceed by a Friedel-Craft type mechanism. (author)

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

    Science.gov (United States)

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

    2014-08-01

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

  4. Highly concentrating Fresnel lenses.

    Science.gov (United States)

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

    1979-08-01

    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

  5. 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

  6. 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.)

  7. 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)

    Gonzalez Vanderhaghen, D.E

    1998-12-31

    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)

  8. Occupational Exposure to Benzene from Painting with Epoxy and Other High Performance Coatings

    Energy Technology Data Exchange (ETDEWEB)

    JAHN, STEVEN

    2005-04-20

    Following the discovery of trace benzene in paint products, an assessment was needed to determine potential for benzene exposures to exceed the established ACGIH Threshold Limit Value (TLV) during painting operations. Sample data was collected by area industrial hygienists for benzene during routine maintenance and construction activities at Savannah River Site. A set of available data from the IH database, Sentry, was analyzed to provide guidance to the industrial hygiene staff and draw conclusions on the exposure potential during typical painting operations.

  9. Benzene: questions and answers

    International Nuclear Information System (INIS)

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

  10. Benzene from catalytic hydrocracking

    Energy Technology Data Exchange (ETDEWEB)

    Cindric, M.

    1982-01-01

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

  11. High concentration plasma-reduced plateletapheresis concentrates.

    Science.gov (United States)

    Perseghin, Paolo

    2011-06-01

    Single-donor hyperconcentrated plateletapheresis (dry-platelets) collection has been introduced in the 90's as a part of the newly developed multi-component collection strategy. This approach allowed to safely collect multiple components from a single apheresis donation, i.e. RBC, FFP and/or plateletpheresis units. Dry-platelets are usually resuspended in additive solution to maintain an adequate pH during the storage period until use. Some concern existed about possible higher degrees of platelet activation in dry-platelets units when compared to standard concentration (1.0-1.6 × 10(6)/?L platelets) units and its possible correlation with lower in vivo efficiency and/or survival of the former units. Several authors investigated this specific issue, and dry-platelets units proved to be equally effective than standard concentration plateletpheresis units in recipients. The use of dry-platelets units may reduce (i) the risk of passive infusion of naturally occurring ABO-related hemolytic antibodies when donor O platelets are given to group A, B, or AB recipient, (ii) the risk of TRALI when multiparous donors undergo plateletpheresis. Furthermore, dry-platelet collection may allow for an increased amount of FFP sent to industry. Finally, hyperconcentrated platelet units may be used for "niche" indications, such as intrauterine platelet transfusion or, in case of autologous dry-platelet collection, for further freezing for long term storage in selected patients within onco-hematological settings. PMID:21507725

  12. Spatial and temporal variations in atmospheric VOCs, NO2, SO2, and O3 concentrations at a heavily industrialized region in Western Turkey, and assessment of the carcinogenic risk levels of benzene

    Science.gov (United States)

    Civan, Mihriban Y?lmaz; Elbir, Tolga; Seyfioglu, Remzi; Kuntasal, Öznur O?uz; Bayram, Abdurrahman; Do?an, Güray; Yurdakul, Sema; Andiç, Özgün; Müezzino?lu, Aysen; Sofuoglu, Sait C.; Pekey, Hakan; Pekey, Beyhan; Bozlaker, Ayse; Odabasi, Mustafa; Tuncel, Gürdal

    2015-02-01

    Ambient concentrations of volatile organic compounds (VOCs), nitrogen dioxide (NO2), sulphur dioxide (SO2) and ground-level ozone (O3) were measured at 55 locations around a densely populated industrial zone, hosting a petrochemical complex (Petkim), a petroleum refinery (Tupras), ship-dismantling facilities, several iron and steel plants, and a gas-fired power plant. Five passive sampling campaigns were performed covering summer and winter seasons of 2005 and 2007. Elevated concentrations of VOCs, NO2 and SO2 around the refinery, petrochemical complex and roads indicated that industrial activities and vehicular emissions are the main sources of these pollutants in the region. Ozone concentrations were low at the industrial zone and settlement areas, but high in rural stations downwind from these sources due to NO distillation. The United States Environmental Protection Agency's positive matrix factorization receptor model (EPA PMF) was employed to apportion ambient concentrations of VOCs into six factors, which were associated with emissions sources. Traffic was found to be highest contributor to measured ?VOCs concentrations, followed by the Petkim and Tupras. Median cancer risk due to benzene inhalation calculated using a Monte Carlo simulation was approximately 4 per-one-million population, which exceeded the U.S. EPA benchmark of 1 per one million. Petkim, Tupras and traffic emissions were the major sources of cancer risk due to benzene inhalation in the Aliaga airshed. Relative contributions of these two source groups changes significantly from one location to another, demonstrating the limitation of determining source contributions and calculating health risk using data from one or two permanent stations in an industrial area.

  13. Benzene dimer: High-level wave function and density functional theory calculations.

    Czech Academy of Sciences Publication Activity Database

    Pito?ák, Michal; Neogrady, P.; ?ezá?, Jan; Jure?ka, Petr; Urban, M.; Hobza, Pavel

    2008-01-01

    Ro?. 4, ?. 11 (2008), s. 1829-1834. ISSN 1549-9618 R&D Projects: GA MŠk LC512 Grant ostatní: SRDA(SK) APVV-20-018405 Institutional research plan: CEZ:AV0Z40550506 Keywords : benzene dimer * wave function calculations * density functional theory calculations Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.274, year: 2008

  14. A quantitative method for estimating dermal benzene absorption from benzene-containing hydrocarbon liquids.

    Science.gov (United States)

    Petty, Stephen E; Nicas, Mark; Boiarski, Anthony A

    2011-01-01

    This study examines a method for estimating the dermal absorption of benzene contained in hydrocarbon liquids that contact the skin. This method applies to crude oil, gasoline, organic solvents, penetrants, and oils. The flux of benzene through occluded skin as a function of the percent vol/vol benzene in the liquid is derived by fitting a curve to experimental data; the function is supralinear at benzene concentrations benzene is on nonoccluded skin, benzene may preferentially evaporate from the liquid, which thereby decreases the benzene flux. We present a time-averaging method here for estimating the reduced dermal flux during evaporation. Example calculations are presented for benzene at 2% vol/vol in gasoline, and for benzene at 0.1% vol/vol in a less volatile liquid. We also discuss other factors affecting dermal absorption. PMID:22069926

  15. 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

  16. Occupational exposure to benzene in China.

    OpenAIRE

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

    1987-01-01

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

  17. High concentration photovoltaic thermal system

    OpenAIRE

    Galagan, A.A.

    2013-01-01

    Researchers from IBM have created a very impressive and affordable new photovoltaic system that is capable of concentrating solar radiation up to 2000 times. The system is also capable of converting 80% of incoming solar radiation into useful energy. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/33625

  18. Case study: High capacity spiral concentrators

    Scientific Electronic Library Online (English)

    P., Ramsaywok; M.K.G., Vermaak; R., Viljoen.

    2010-11-01

    Full Text Available Spiral concentrators are compact, cost-effective and generally efficient gravity concentration separators for a wide range of applications (for example: coal, beach sands, iron ore, chromite and tantalite). Large mineral processing plants consist of thousands of spiral concentrators resulting in lar [...] ge plant footprints (capital intensive) and the adjustment of splitters is time consuming, impractical and is in many cases neglected-high capacity (HC) spiral concentrators aim to address these shortcomings. As a result Exxaro Namakwa Sands is currently investigating high capacity spiral technology for the spiral circuit upgrade at the primary concentrator plants (PCPs). This article summarizes the rougher spiral performance evaluation that was conducted on different types of spiral concentrators (the traditional MG4 spiral concentrator and the high capacity (HC) spiral concentrator) under different feed conditions. In addition, the effect of slimes on the spiral concentrator performance was also investigated. Slimes rheology was linked to the poor concentrator performance at the higher slimes concentrations. The test campaign shows a sacrifice in recovery under design-feed conditions can be expected when using high capacity spiral concentrators in the rougher stage when compared to traditional spiral technology currently in use. Both spiral concentrators show a detrimental impact of slimes on the performance, but the high capacity spiral concentrator is more sensitive to the higher slimes conditions.

  19. Proposal of structures possessing high exciton concentration

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Hodge, R C

    1982-04-01

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

  1. Mechanistic considerations in benzene physiological model development.

    OpenAIRE

    Medinsky, M. A.; Kenyon, E. M.; Seaton, M. J.; Schlosser, P. M.

    1996-01-01

    Benzene, an important industrial solvent, is also present in unleaded gasoline and cigarette smoke. The hematotoxic effects of benzene in humans are well documented and include aplastic anemia, pancytopenia, and acute myelogenous leukemia. However, the risks of leukemia at low exposure concentrations have not been established. A combination of metabolites (hydroquinone and phenol, for example) may be necessary to duplicate the hematotoxic effect of benzene, perhaps due in part to the synergis...

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

    Science.gov (United States)

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

    2012-12-01

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

  3. Low level occupational benzene exposure and hematological parameters.

    Science.gov (United States)

    Swaen, Gerard M H; van Amelsvoort, Ludovic; Twisk, Johannes J; Verstraeten, Etienne; Slootweg, Ronald; Collins, James J; Burns, Carol J

    2010-03-19

    At high and prolonged exposure levels (e.g. >30 ppm), benzene can cause hematological effects. However, there is conflicting evidence on potential hematological effects at lower concentrations. We conducted a study to examine hematological effects at low benzene exposure levels in an occupational setting. Extensive exposure data and data from routine hematology examinations were available for Dow employees at the Terneuzen site in the Netherlands. We compared 8532 blood samples of Dow employees with low benzene exposure to 12,173 samples of employees with no benzene exposure that were available for the period between 1981 and 2007. Based on 21,584 benzene air measurements, a Job Exposure Matrix (JEM) was constructed for all employees with exposure. The JEM was used to estimate benzene exposure in the year in which each blood sample was collected. The average lymphocyte counts for the exposed and non-exposed group were similar. By means of mixed model regression adjustments were made for smoking, age and month of blood sample. These adjustments did not change the results and there was no indication for an adverse effect on any of the hematological parameters under investigation. A further stratification of the exposed population into three subgroups (1 ppm) showed no significant differences for any of the hematological parameters between the three exposure categories or compared with the non-exposed group. The analysis modeling the continuous exposure effect relationship showed similar findings. This study does not indicate that workers exposed to low benzene concentrations are at an increased risk for hematological effects. PMID:20074561

  4. 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

  5. Photovoltaic concentration at ultra-high flux

    Science.gov (United States)

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

    2004-09-01

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

  6. Ionization and high-order harmonic generation in aligned benzene by a short intense circularly polarized laser pulse

    International Nuclear Information System (INIS)

    We present a first-principles study of ionization and high-order harmonic generation by benzene aligned in the polarization plane of a short circularly polarized laser pulse. Time-dependent density-functional theory within the adiabatic local-density approximation is employed to describe the 30 valence-electron dynamics in three dimensions. The multielectron approach enables us to study the effect of very strong laser fields, 1014-1015 W cm-2, where multiple ionization and high-order harmonic generation interplay. Large ionization currents are formed, causing ionization of 1-4 electron charges, while strong high-order harmonic generation is observed. The well-known recollision mechanism of high-order harmonic generation plays a part for moderate laser intensities but is fully suppressed for strong laser fields. The harmonic generation spectra are characterized by two distinguishable plateaus, where the structure of the first plateau is dominated by the 6k±1 (k=0,1,...) selection rule. The number of harmonics in the second plateau is insensitive to the duration of the pulse. The peaks appear in pairs or in threesomes, depending on the pulse duration

  7. Biotransformation of toluene, benzene and naphthalene under anaerobic conditions.

    OpenAIRE

    Langenhoff, A. A. M.

    1997-01-01

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

  8. (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

  9. On the Nature of Active Sites in Benzene Oxidation to Phenol with N2O over H-ZSM-5 with Low Fe Concentrations.

    Czech Academy of Sciences Publication Activity Database

    Kubánek, Petr; Wichterlová, Blanka; Sobalík, Zden?k

    2002-01-01

    Ro?. 211, ?. 1 (2002), s. 109-118. ISSN 0021-9517 R&D Projects: GA AV ?R IAA4040007 Institutional research plan: CEZ:AV0Z4040901 Keywords : H-ZSM-5 * Fe-zeolites * N2O oxidation of benzene Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.118, year: 2002

  10. Determination of the unburnt benzene in the autovehicular emission

    International Nuclear Information System (INIS)

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

  11. High efficiency compound semiconductor concentrator photovoltaics

    Science.gov (United States)

    Borden, P.; Gregory, P.; Saxena, R.; Owen, R.; Moore, O.

    1980-01-01

    Special emphasis was given to the high yield pilot production of packaged AlGaAs/GaAs concentrator solar cells, using organometallic VPE for materials growth, the demonstration of a concentrator module using 12 of these cells which achieved 16.4 percent conversion efficiency at 50 C coolant inlet temperature, and the demonstration of a spectral splitting converter module that achieved in excess of 20 percent efficiency. This converter employed ten silicon and ten AlGaAs cells with a dichroic filter functioning as the beam splitter. A monolithic array of AlGaAs/GaAs solar cells is described.

  12. The fate of benzene-oxide.

    Science.gov (United States)

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

    2010-03-19

    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

  13. A high concentration rooftop photovoltaic system

    Science.gov (United States)

    Gleckman, Philip

    2007-09-01

    The commercial rooftop environment poses difficult challenges for concentrating photovoltaic (CPV) systems. Rooftop CPV must not only meet low cost and high energy production targets common to ground mounted systems but also must solve safety, wind loading, and area usage requirements in ways that are compatible with the rooftop environment. To meet these requirements we have developed a low-profile carousel-mounted array of Fresnel concentrators using triple junction solar cells. In this paper we describe the key features of the opto-mechanical and thermal design for manufacturability and reliability. These features include the concentration level, the mechanical drive scheme, the configuration of the lens with secondary optical element, and passive cooling. Also described are elements of the optical component testing and assembly methods. We present exemplary results of environmental testing and measurements of electro-optical performance.

  14. Cellulase Inhibition by High Concentrations of Monosaccharides

    DEFF Research Database (Denmark)

    Hsieh, Chia-Wen; Cannella, David

    2014-01-01

    Biological degradation of biomass on an industrial scale culminates in high concentrations of end products. It is known that the accumulation of glucose and cellobiose, end products of hydrolysis, inhibit cellulases and decrease glucose yields. Aside from these end products, however, other monosaccharides such as mannose and galactose (stereoisomers of glucose) decrease glucose yields as well. NMR relaxometry measurements showed direct correlations between the initial T 2 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 e ff ect was most likely due to catalytic, and not binding, inhibition of the cellulases.

  15. Influence of toluene co-exposure on the metabolism and genotoxicity of benzene in mice using continuous and intermittent exposures.

    Science.gov (United States)

    Bird, M G; Wetmore, B A; Letinski, D J; Nicolich, M; Chen, M; Schnatter, A R; Whitman, F T

    2010-03-19

    Benzene exposure in occupational settings often occurs with concurrent exposure to toluene, the methyl-substituted derivative of benzene. Toluene is also readily metabolized by CYP450 isozymes although oxidation primarily occurs in the methyl group. While earlier mouse studies addressing co-exposure to benzene and toluene at high concentrations demonstrated a reduction in benzene-induced genotoxicity, we have previously found, using an intermittent exposure regimen with lower concentrations of benzene (50 ppm) and toluene (100 ppm), that toluene enhances benzene-induced clastogenic or aneugenic bone marrow injury in male CD-1 mice with significantly increased CYP2E1, and depleted GSH and GSSG levels. The follow-up study reported here also used the same daily and total co-exposures but over consecutive days and compared the effects of co-exposure on genotoxicity and metabolism in CD-1 mice both with and without buthionine sulfoximine (BSO) treatment to deplete GSH. In this study the toluene co-exposure doubled the genotoxic response (as determined by the erythrocyte micronucleus test) to benzene alone. Further, GSH depletion caused a reduction in this genotoxicity in both benzene exposed and benzene/toluene co-exposed mice. The results are discussed in terms of the analyses of urinary metabolites from this consecutive day study and the intermittent exposure study as well as levels of CYP2E1, epoxide hydrolase, quinone reductase, alcohol dehydrogenase, and aldehyde dehydrogenase activities. The results suggest that the presence of glutathione is necessary for benzene genotoxicity either as a metabolite conjugate or through an indirect mechanism such as TNF-induced apoptosis. PMID:20079720

  16. Multijunction high voltage concentrator solar cells

    Science.gov (United States)

    Valco, G. J.; Kapoor, V. J.; Evans, J. C.; Chai, A.-T.

    1981-01-01

    The standard integrated circuit technology has been developed to design and fabricate new innovative planar multi-junction solar cell chips for concentrated sunlight applications. This 1 cm x 1 cm cell consisted of several voltage generating regions called unit cells which were internally connected in series within a single chip resulting in high open circuit voltages. Typical open-circuit voltages of 3.6 V and short-circuit currents of 90 ma were obtained at 80 AM1 suns. A dramatic increase in both short circuit current and open circuit voltage with increased light levels was observed.

  17. High-resolution stimulated Brillouin gain spectroscopy of liquid benzene shows no evidence of a open-quotes structural transitionclose quotes

    International Nuclear Information System (INIS)

    We have used high-resolution stimulated Brillouin gain spectroscopy to search for evidence of a open-quotes structural transitionclose quotes within the liquid phase of benzene. On the basis of previous measurements of depolarized light scattering intensities and Brillouin line shifts, it has been proposed that such a transition occurs in the temperature range 42-48 degrees C. Our highly accurate Brillouin shift measurements show a linear dependence on temperature from 24 to 69 degrees C, with no sign of any anomaly. 23 refs., 2 figs

  18. High-resolution stimulated Brillouin gain spectroscopy of liquid benzene shows no evidence of a {open_quotes}structural transition{close_quotes}

    Energy Technology Data Exchange (ETDEWEB)

    Grubbs, W.T.; MacPhail, R.A. [Duke Univ., Durham, NC (United States)

    1992-10-29

    We have used high-resolution stimulated Brillouin gain spectroscopy to search for evidence of a {open_quotes}structural transition{close_quotes} within the liquid phase of benzene. On the basis of previous measurements of depolarized light scattering intensities and Brillouin line shifts, it has been proposed that such a transition occurs in the temperature range 42-48 {degrees}C. Our highly accurate Brillouin shift measurements show a linear dependence on temperature from 24 to 69 {degrees}C, with no sign of any anomaly. 23 refs., 2 figs.

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

    Scientific Electronic Library Online (English)

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

    1227-12-01

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

  20. 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

  1. Incense, sparklers and cigarettes are significant contributors to indoor benzene and particle levels

    Scientific Electronic Library Online (English)

    Werner, Tirler; Gaetano, Settimo.

    2015-03-01

    Full Text Available Introduction. The increased use of incense, magic candles and other flameless products often produces indoor pollutants that may represent a health risk for humans. Today, in fact, incense and air fresheners are used inside homes as well as in public places including stores, shopping malls and place [...] s of worship. As a source of indoor contamination, the impact of smoke, incense and sparklers on human health cannot be ignored. Aim. In the present work, we report the results of an emission study regarding particles (PM10 and particle number concentration, PNC) and benzene, produced by various incense sticks and sparklers. Results and discussion.The results obtained for benzene, PM10 and PNC, showed a strong negative influence on air quality when these products were used indoors. Various incense sticks gave completely different benzene results: from a small increase of the benzene concentration in the air, just slightly above the background levels of ambient air, to very high concentrations, of more than 200 µg/m³ of benzene in the test room after the incense sticks had been tested.

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

    International Nuclear Information System (INIS)

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

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

    DEFF Research Database (Denmark)

    Emmerling, Uwe; Rasmussen, Peter

    1998-01-01

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

  4. 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)

  5. Materials processing using highly concentrated solar radiation

    International Nuclear Information System (INIS)

    Highly concentrated radiant energy provides a controllable means of delivering large flux densities (>100 W/cm2) to solid surfaces. The resulting thermal energy can cause phase changes, atomic migrations, and chemical reactions on a surface without greatly perturbing the bulk properties, or the photons may directly interact with species on the surface to induce some desirable interaction. In a suitably designed solar furnace this flux can be delivered over large areas or tailored to accommodate particular processing requirements. Furthermore, this occurs without the environmental liability associated with providing power to more conventional light sources. Research to date has demonstrated the possibility of performing several interesting surface modifications, including phase transformation hardening of steels, melting powders or preapplied coatings to form fully dense, well-bonded coatings, initiation of self-propagating high-temperature synthesis reactions, rapid thermal annealing, and chemical vapor deposition. Particularly interesting results have been obtained in the cladding work, and the results of efforts to control the physical properties of the interfacial regions of coatings on steel is discussed

  6. High concentration of deuterium in palladium

    International Nuclear Information System (INIS)

    In this paper, based on theoretical calculations, new schemes to increase the deuterium density in palladium over its initial value are presented. A high deuterium concentration in palladium is needed for application to solid-state fusion. The first deuterium enrichment scheme makes use of plasma ion implantation, which consists of a cylindrical palladium rod (target) preloaded with deuterium atoms, coated with diffusion barrier material, and immersed in a deuterium plasma. The palladium rod is connected to a high-power modulator, which provides a series of negative voltage pulses. During these negative pulses, deuterium ions fall on the target, penetrate the diffusion barrier, and are implanted inside the palladium. For reasonable system parameters allowed by current technology, theoretical calculations indicate that the saturation deuterium density after prolonged ion implantation can be several times the palladium atomic number density. The second deuterium enrichment scheme makes use of temperature gradient effects on the deuterium solubility in palladium. A heat source at temperature T2 and a heat sink at temperature T1 (where T2 > T1) are in contact with two different parts of a palladium sample, which has been presoaked with deuterium atoms and has been coated with diffusion barrier material or has been securely locked in a metal case. The temperature gradient created in the sample from such an arrangement forces the ample from such an arrangement forces the deuterium atoms in the hot region to migrate into the cold region, resulting in higher deuterium density in the cold region

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-12-15

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

  8. Fungal adaptation to extremely high salt concentrations.

    Science.gov (United States)

    Gostin?ar, Cene; Lenassi, Metka; Gunde-Cimerman, Nina; Plemenitaš, Ana

    2011-01-01

    Hypersaline environments support substantial microbial communities of selected halotolerant and halophilic organisms, including fungi from various orders. In hypersaline water of solar salterns, the black yeast Hortaea werneckii is by far the most successful fungal representative. It has an outstanding ability to overcome the turgor loss and sodium toxicity that are typical for hypersaline environments, which facilitates its growth even in solutions that are almost saturated with NaCl. We propose a model of cellular responses to high salt concentrations that integrates the current knowledge of H. werneckii adaptations. The negative impact of a hyperosmolar environment is counteracted by an increase in the energy supply that is needed to drive the energy-demanding export of ions and synthesis of compatible solutes. Changes in membrane lipid composition and cell-wall structure maintain the integrity and functioning of the stressed cells. Understanding the salt responses of H. werneckii and other fungi (e.g., the halophilic Wallemia ichthyophaga) will extend our knowledge of fungal stress tolerance and promote the use of the currently unexploited biotechnological potential of fungi that live in hypersaline environments. PMID:22050822

  9. Benzene monitoring at CPPI service stations

    International Nuclear Information System (INIS)

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

  10. High-Temperature, High-Concentration Solar Thermoelectric Generators

    Science.gov (United States)

    Warren, Emily; Baranowski, Lauryn; Olsen, Michele; Ndione, Paul; Netter, Judy; Goodrich, Alan; Gray, Matthew; Parilla, Philip; Ginley, David; Toberer, Eric

    2014-03-01

    Solar thermoelectric generators (STEGs) powered with concentrated solar energy have potential for use as primary energy converters or as topping-cycles for more conventional concentrated solar power (CSP) technologies. Modeling based on current record modules from JPL suggests thermoelectric efficiencies of 18 % could be experimentally expected with a temperature gradient of 1000 - 100°C. Integrating these state-of-the-art TEGs with a concentrating solar receiver requires simultaneous optimization of optical, thermal, and thermoelectric systems. This talk will discuss the modeling, design, and experimental testing of STEG devices under concentrated sunlight. We have developed a model that combines thermal circuit modeling with optical ray tracing to design selective absorber coatings and cavities to minimize radiation losses from the system. We have fabricated selective absorber coatings and demonstrated that these selective absorber films can minimize blackbody radiation losses at high temperature and are stable after thermal cycling to 1000°C. On-sun testing of STEG devices and thermal simulators is ongoing and preliminary results will be discussed.

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

    Directory of Open Access Journals (Sweden)

    M. Samarghandi

    2014-01-01

    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

  12. Linewidths and high resolution structure of the benzene 1B2u?1A1g two photon transition by multiphoton ionization-supersonic beam techniques

    Science.gov (United States)

    Aron, Kenneth; Otis, Charles; Demaray, R. Ernest; Johnson, Philip

    1980-11-01

    The two photon spectra of the 1B2u state of benzene-h6 and benzene-d6 have been examined in a supersonic molecular beam/multiphoton ionization experiment. The effect of channel three nonradiative decay on the resonance linewidths was followed through energies greater than 6000 cm-1 above the origin, 3000 cm-1 past the fluorescence cutoff region. The linewidth data suggest a leveling off of the channel three broadening at energies greater than T00+6000 cm-1. A new progression in the benzene-h6 spectrum was revealed adjacent to the 1410 1n0 progression (n=1 to 5) which had previously been obscured in the rotational envelope of these bands. New structure and well resolved expected structure is seen in the benzene-d6 spectrum as the 1410 1n0 progression is followed out to n=5.

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

    International Nuclear Information System (INIS)

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

  14. High-concentrated neodymium laser glasses

    International Nuclear Information System (INIS)

    An effect of a change in R molar ratio on concentration quenching of Nd3+ luminescence (cql) in phosphate glasses has been studied. A change in tau life time of a metastable state of 4Fsub(3/2)Ndsup(3+) has been investigated when R varies from 0.47 to 1.09 for two series of glasses of Li2O-Nd2O3-P2O5 and BaO-Nd2O3-P2O5. The highest tau values for Nd3+ are attained in the glasses of ultraphosphate composition (0 3+ irrespective of chemical composition of modifying oxides

  15. 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

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

    Directory of Open Access Journals (Sweden)

    SB Mortazavi, A Sabzali, A Rezaee

    2005-04-01

    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.

  17. Chromosome aberrations induced by ?-rays combined with benzene in cultured human peripheral blood lymphocytes

    International Nuclear Information System (INIS)

    The authors reported on the changes of combined chromosome aberrations induced ?-rays irradiation and benzene in human blood lymphocytes. The results were summarized as follows: The chromosome and chromatid type aberrations can be induced by benzene. Neither dicentrics nor rings were observed. When the cells were treaded with benzene, the yield of chromosome aberration induced by radiation can be enhanced. In the definite dose range, the chromosome aberrations induced by radiation combined with benzene were increased as benzene concentration increasing for graving radiation dose. Benzene concentration and total aberration cells give a good fit to the linear regression equation. There were good relations between doses of radiation combined with tree variant benzene concentration and chromosome aberration rate. All of them give a good fit to the power regression equation

  18. Production of glucose syrups in highly concentrated systems.

    Science.gov (United States)

    van der Veen, M E; van der Goot, A J; Boom, R M

    2005-01-01

    We have investigated the hydrolysis of maltodextrins in a high concentration (up to 70%), by means of enzymatic and acid catalysis. The study revealed that the equilibrium compositions of the catalyzed reactions were kinetically determined by the selectivity of the catalyst, the substrate concentration and the reaction time. A model comprising a set of two kinetic equations was used to describe the hydrolysis and condensation reactions of glucoamylase-catalyzed reactions, even to highly concentrated systems. Increased substrate concentration resulted in the formation of more condensation products. The enzyme inhibition was low and was found to be independent of the substrate concentration. PMID:15801804

  19. Economical benzene emission reduction

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2009-09-01

    Because crude oil contains up to 3% benzene and there is an association between high chronic exposure to appreciable concentrations of benzene and acute myelogenous leukemia, exposure of refinery workers has been studied for many years. To date, no extensive industrial hygiene exposure analyses for historical benzene exposure have been performed, and none have focused on the airborne concentrations in the workplace at specific refineries or for specific tasks. In this study, the authors evaluated the airborne concentrations of benzene and their variability over time at the ExxonMobil refinery in Baton Rouge between 1977 and 2005. Refinery workers were categorized into 117 worker groups using company job descriptions. These 117 groups were further collapsed into 25 job categories based on similarity of measured exposure results. Results of 5289 personal air samples are included in this analysis; 3403 were considered nontask (>or= 180 min) personal samples, and 830 were considered task-related (benzene concentrations: analyzers (mean = 0.12 ppm), coker (mean = 0.013 ppm), hydrofiner (mean = 0.0054 ppm), lube blending and storage (mean = 0.010 ppm), waste treatment (mean = 0.092 ppm), and all other areas (mean = 0.055 ppm). Task-based samples indicated that the highest exposures resulted from the sampling tasks, specifically from those performed on process materials; in general, though, even these tasks had concentrations well below the STEL of 5 ppm. The most frequently sampled task was gauging (mean = 0.12 ppm). Task-related exposures were also similar across job categories for a given task, with a few exceptions. This study thus provides a task-focused analysis for occupational exposure to benzene during refinery operations, which can be insightful for understanding exposures at this refinery and perhaps others operated since about 1975. PMID:19544135

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

    International Nuclear Information System (INIS)

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

  2. 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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1993-08-01

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

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

    International Nuclear Information System (INIS)

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

  5. Biodegradation of Benzene by Halophilic and Halotolerant Bacteria under Aerobic Conditions

    OpenAIRE

    A. Nicholson, Carla; Z. Fathepure, Babu

    2004-01-01

    A highly enriched halophilic culture was established with benzene as the sole carbon source by using a brine soil obtained from an oil production facility in Oklahoma. The enrichment completely degraded benzene, toluene, ethylbenzene, and xylenes within 1 to 2 weeks. Also, [14C]benzene was converted to 14CO2, suggesting the culture's ability to mineralize benzene. Community structure analysis revealed that Marinobacter spp. were the dominant members of the enrichment.

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

    OpenAIRE

    Sb Mortazavi, A. Sabzali

    2005-01-01

    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 ...

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

    Directory of Open Access Journals (Sweden)

    A Palasuwan

    2013-01-01

    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.

  8. Methane-benzene binary mixture destruction in a reverse flow catalytic reactor

    International Nuclear Information System (INIS)

    A reverse flow reactor (RFR) is a packed catalytic bed reactor in which feed flow direction is periodically reversed. When an exothermic catalytic combustion is conducted in a RFR, a hot zone is trapped in the center while both ends of the reactor act as regenerative heat exchanger. This enables an auto thermal operation at high temperatures even for feeds having a low adiabatic temperature rise. These features make RFR highly competitive for VOCs combustion. An experimental study of binary mixture purification in bench scale reverse flow reactor, with an inner diameter of 60 mm, has been carried out. Methane and benzene are chosen due to their different properties. The ignition temperature of methane is higher than any other hydrocarbons and benzene is widely used as solvent in industry. With periodic reversal feed, auto thermal catalytic combustion of very lean binary mixture can be achieved. When peak temperature in the hot zone reaches about 550 degree Celsius, both methane and benzene are well removed and little NOx or no other secondary pollutants are detected. The influence of several operation parameters, such as gas velocity, cycle period and methane-to-benzene ratio are discussed. A mathematical model has been developed and solved using a FORTRAN code, good correspondence being observed between both approaches. This provides a solution if VOC concentration in the contaminated air is too low to maintain an auto thermal operation, while natural gas (which is ml operation, while natural gas (which is mainly methane) can be added as auxiliary fuel. (author)

  9. Production of glucose syrups in highly concentrated systems

    OpenAIRE

    Veen, M.E., van der; Goot, A.J., van der; Boom, R.M.

    2005-01-01

    We have investigated the hydrolysis of maltodextrins in a high concentration (up to 70%), by means of enzymatic and acid catalysis. The study revealed that the equilibrium compositions of the catalyzed reactions were kinetically determined by the selectivity of the catalyst, the substrate concentration and the reaction time. A model comprising a set of two kinetic equations was used to describe the hydrolysis and condensation reactions of glucoamylase-catalyzed reactions, even to highly conce...

  10. Applications of nonimaging optics for very high solar concentrations

    Energy Technology Data Exchange (ETDEWEB)

    O`Gallagher, J.; Winston, R.

    1997-12-31

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Steven B. Hawthorne

    2007-04-15

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

  12. 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.

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

    Directory of Open Access Journals (Sweden)

    Fadhil M. Salih

    2011-07-01

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

  14. 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)

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

    Science.gov (United States)

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

    2010-05-01

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

  16. 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)

  17. Europium doped lanthanum zirconate nanoparticles with high concentration quenching

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Eu:La2Zr2O7 nanoparticles were prepared facilely by a kinetically modified molten salt method. • High color purity and concentration quenching were achieved in these La2Zr2O7:Eu nanoparticles. • Concentration quenching mechanism was discussed for Eu3+ in these Eu:La2Zr2O7 nanoparticles. - Abstract: A series of Eu3+ doped lanthanum zirconate (La2Zr2O7) nanoparticles (NPs, 20 ± 5 nm in diameter) with cubic fluorite structure were facilely synthesized by a kinetically modified molten salt synthetic (MSS) process and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and photoluminescence spectra (PL). Under the excitation of 405 nm, intense red emission with high color purity can be observed in the Eu3+ doped La2Zr2O7 NPs. Moreover, the as-prepared Eu:La2Zr2O7 NPs possess high concentration quenching, which is as high as ?32.5 mol% of europium dopants in the La2Zr2O7 host. The corresponding concentration quenching mechanism was discussed as well. Our results confirm that the kinetically modified MSS process is a promising approach for preparing rare earth (RE) ions doped A2B2O7 nanoparticles with uniform RE doping and high concentration quenching

  18. 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)

  19. 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

  20. Phase hologram formation in highly concentrated phenanthrenequinone PMMA media

    Science.gov (United States)

    Mahilny, U. V.; Marmysh, D. N.; Tolstik, A. L.; Matusevich, V.; Kowarschik, R.

    2008-08-01

    For phase holographic gratings in layers of polymethylmethacrylate, containing phenanthrenequinone in high concentration (nearly 3 mol%), a discrepancy between experimental (up to 9) and estimated (~45) magnitudes of the thermal diffusion amplification coefficient has been revealed. Analysis of plausible reasons of the lower experimental efficiency of the diffusion amplification has been carried out. The influence of material deformations on the reflection grating formation process was investigated experimentally. It is shown that thermoactivated amplification of holograms under high phenanthrenequinone concentration and its profound modulation are depressed by the arising density 'grating'.

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

    DEFF Research Database (Denmark)

    andersen, susanne; Tonboe, R.

    2007-01-01

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

  2. Analyses of chromosome aberrations in lymphocytes and bone marrow cells induced by radiation or benzene

    International Nuclear Information System (INIS)

    The chromosome and chromatid type aberration can be induced by benzene and the dicentric and ring ones were not observed in vitro experiment but observed in vivo one. In vitro experiment a good linear regression can be given between benzene concentrations and total aberration cells while power regression for radiation dose. The chromosome aberrations induced by benzene combined with radiation in rabbit blood lymphocytes are higher than in bone marrow cells

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

    OpenAIRE

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

    1996-01-01

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

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

    Science.gov (United States)

    Sarhan, Wessam A; Azzazy, Hassan M E

    2015-05-20

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

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

    Directory of Open Access Journals (Sweden)

    J. H. Seinfeld

    2007-03-01

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

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

    OpenAIRE

    Derry, S; Sven-Rice, A; Cole, P.; Tan, T; Moore, RA

    2013-01-01

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

  7. Beryllium-10 concentrations in water samples of high northern latitudes

    Energy Technology Data Exchange (ETDEWEB)

    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

    {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.

  8. Improved Dispersion of Carbon Nanotubes in Polymers at High Concentrations

    OpenAIRE

    Chao-Xuan Liu; Jin-Woo Choi

    2012-01-01

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

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

    Science.gov (United States)

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

    2014-11-28

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-10-28

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

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

    International Nuclear Information System (INIS)

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

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

    Scientific Electronic Library Online (English)

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

    2011-06-01

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

  13. High-flux characterization of ultrasmall multijunction concentrator solar cells

    Science.gov (United States)

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

    2007-08-01

    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.

  14. High-concentration photovoltaic designs based on miniature parabolic dishes

    Science.gov (United States)

    Feuermann, Daniel; Gordon, Jeffrey M.

    2001-11-01

    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.

  15. 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.

  16. 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

  17. Copper uptake by Eichhornia crassipes exposed at high level concentrations.

    Science.gov (United States)

    Melignani, Eliana; de Cabo, Laura Isabel; Faggi, Ana María

    2015-06-01

    The objective of this study was to assess the growth of water hyacinth (Eichhornia crassipes) and its ability to accumulate Cu from polluted water with high Cu concentrations and a mixture of other contaminants under short-term exposure, in order to use this species for the remediation of highly contaminated sites. Two hydroponic experiments were performed under greenhouse conditions for 7 days. One of them consisted of growing water hyacinth in Hoagland solution supplemented with 15 or 25 mg Cu/L and a control. The other one contained water hyacinth growing in polluted river water supplemented with 15 mg Cu/L and a control. Cu was accumulated principally in roots. The maximum Cu concentration was 23,387.2 mg/kg dw in the treatment of 25 mg Cu/L in Hoagland solution. Cu translocation from roots to leaves was low. The mixture of 15 mg Cu/L with polluted water did not appear to have toxic effects on the water hyacinth. This plant showed a remarkable uptake capacity under elevated Cu concentrations in a mixture of pollutants similar to pure industrial effluents in a short time of exposure. This result has not been reported before, to our knowledge. This species is suitable for phytoremediation of waters subject to discharge of mixed industrial effluents containing elevated Cu concentrations (?15 mg Cu/L), as well as nutrient-rich domestic wastewaters. PMID:25529492

  18. High microfilament concentration results in barbed-end ADP caps.

    Science.gov (United States)

    Dufort, P A; Lumsden, C J

    1993-01-01

    Current theory and experiments describing actin polymerization suggest that site-specific cleavage of bound nucleotide following F-actin filament formation causes the barbed ends of microfilaments to be capped first with ATP subunits, then with ADP bound to inorganic phosphate (ADP.Pi) at steady-state. The barbed ends of depolymerizing filaments consist of ADP subunits. The decrease in stability of the barbed-end cap accompanying the transition from ADP.Pi to ADP allows nucleotide hydrolysis and subsequent loss of Pi to regulate F-actin filament dynamics. We describe a novel computational model of nucleotide capping that simulates both the spatial and temporal properties of actin polymerization. This model has been used to test the effects of high filament concentration on the behavior of the ATP hydrolysis cycle observed during polymerization. The model predicts that under conditions of high microfilament concentration an ADP cap can appear during steady-state at the barbed ends of filaments. We show that the presence of the cap can be accounted for by a kinetic model and predict the relationship between the nucleotide concentration ratio [ATP]/[ADP], the F-actin filament concentration, and the steady-state distribution of barbed-end ADP cap lengths. The possible consequences of this previously unreported phenomenon as a regulator of cytoskeletal behavior are discussed. Images FIGURE 2 FIGURE 3 FIGURE 6 PMID:8298009

  19. Major sources of benzene exposure.

    OpenAIRE

    Wallace, L.A.

    1989-01-01

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

  20. 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

  1. Effects of Benzene on human hematopoiesis

    OpenAIRE

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

    2008-01-01

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

  2. 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)

  3. Study on recovery of uranium from high concentration uranium solution

    International Nuclear Information System (INIS)

    The technology of recovery uranium from high concentration uranium solution is studied. The operation and control of the technology are improved through taking some measures such as using a new type of ion exchange column, choosing high capacity ion exchange resin, enhancing adsorption quality of adsorption solution, strengthening discharge solution of ion exchange process and using new elution operation. The more than two years' production shows that the technology has the better economic benefits. Some technological parameter and technical index have reached the advanced level of the world

  4. Improved Dispersion of Carbon Nanotubes in Polymers at High Concentrations

    Directory of Open Access Journals (Sweden)

    Chao-Xuan Liu

    2012-10-01

    Full Text Available The polymer nanocomposite used in this work comprises elastomer poly(dimethylsiloxane (PDMS as a polymer matrix and multi-walled carbon nanotubes (MWCNTs as a conductive nanofiller. To achieve uniform distribution of carbon nanotubes within the polymer, an optimized dispersion process was developed, featuring a strong organic solvent—chloroform, which dissolved PDMS base polymer easily and allowed high quality dispersion of MWCNTs. At concentrations as high as 9 wt.%, MWCNTs were dispersed uniformly through the polymer matrix, which presented a major improvement over prior techniques. The dispersion procedure was optimized via extended experimentation, which is discussed in detail.

  5. Accurate modeling of ionic surfactants at high concentration.

    Science.gov (United States)

    Goh, Garrett B; Eike, David M; Murch, Bruce P; Brooks, Charles L

    2015-05-21

    Molecular dynamics (MD) simulation is a useful tool for simulating formulations of surfactant mixtures from first-principles, which can be used to predict surfactant morphology and other industrially relevant thermodynamic properties. However, the surfactant structure is sensitive to the parameters used in MD simulations, and in the absence of extensive validation against experimental data, it is often not obvious a priori which range of parameter sets to choose. In this work, we compare the performance of ion parameters implemented in nonpolarizable classical MD simulations, and its effect on simulations of an idealized solution of sodium dodecyl sulfate (SDS). We find that previous artifacts reported in simulations of larger SDS constructs are a direct consequence of using parameters that poorly model ionic interactions at high concentration. Using osmotic pressure and/or other thermodynamic properties measured at finite concentration, such as Kirkwood-Buff integrals, is shown to be the most cost-effective means to validate and parametrize existing force fields. Our findings highlight the importance of optimizing intermolecular parameters for simulations of systems with a high local concentration, which may be applicable in other contexts, such as in molecular crowding, hotspot mapping, protein folding, and modeling pH effects. PMID:25913469

  6. Optical design considerations for high-concentration photovoltaics

    Science.gov (United States)

    Garboushian, Vahan; Gordon, Robert

    2006-08-01

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

  7. Influence of natural attenuation and river fluctuations on benzene dispersion in an alluvial aquifer subject to strong interactions with surface water

    OpenAIRE

    Batlle-Aguilar, Jordi; Brouyère, Serge; Dassargues, Alain; Morasch, Barbara; Hunkeler, Daniel

    2010-01-01

    A contaminated alluvial aquifer, in a former gasworks factory and discharging to an adjacent river, was the object of field and laboratory investigations to assess pollutant attenuation and dispersion. Various organic and inorganic compounds were found in the aquifer in concentrations exceeding regulatory values, among them, benzene, which was presenting the major worry for off-site dispersion, mainly due to its mobility and high concentration, i.e. up to 750 mg L-1 in the source zone. Howeve...

  8. 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)

  9. 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)

  10. Mitigation of houses with extremely high indoor radon concentrations

    International Nuclear Information System (INIS)

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

  11. Mitigation of houses with extremely high indoor radon concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Jiranek, M. [Czech Technical University, Faculty of Civil Engineering, Prague (Czech Republic); Neznal, M. [Radon v.o.s., Prague (Czech Republic)

    2006-07-01

    Full text of publication follows: The paper reports on the experience of the Czech Technical University in dealing with mitigation of houses in which unusually high indoor radon concentrations were found. The whole process of remediation is illustrated by example of an old single-family house that was built in the area formed by highly permeable soils with high radon content in the soil air. T he house has a small cellar located under 1/5 of the ground floor area. Two types of floors, i.e. timber floors and cracked concrete slabs were found in the house. As a result of extremely high radon concentration in the sub-floor region (up to 600 kBq/m{sup 3}) and leaky structures in contact with soil, radon concentrations around 100 kBq/m{sup 3} in the cellar and up to 60 kBq/m{sup 3} in the living rooms on the ground floor were measured prior to mitigation. Mitigation measures that were carried out in the house consist of reconstruction of timber floors and installation of active soil depressurization. Timber floors were replaced with concrete slab fitted with damp proof membrane, thermal insulation and floor covering. The soil depressurization system was made up of two sections. The first section is composed of the network of perforated pipes inserted in the drainage layer placed under the new floors and four perforated tubes drilled under the existing floors. The soil air from this section is extracted by means of a roof fan installed at the top of the vertical exhaust pipe running inside the living space and terminating above the roof. The second section was designed to withdraw by means of a small fan radon-laden air from the filling in the floor above the cellar and from perforated tubes drilled into the sub-floor region under the rooms adjacent to the cellar. It serves also for the active ventilation of the cellar. Pressure, temperature and radon concentration sensors were installed into the drainage layer during the reconstruction of floors to record variations in these parameters caused by soil ventilation and depressurization. Measured data were used not only for the verification of the remediation effectiveness, but also for the analysis of possible negative effects (reduced under floor temperatures, drying and freezing of the subsoil, etc.). Investigation of these effects is very important, because they can lead to additional settlement of the house resulting in appearance of micro -cracks in the house substructure. To minimize negative effects both fans operate in intermittent mode with the frequency of operating periods depending on the rate of decrease and increase of indoor radon concentration after switching on and off the fans. The effectiveness of installed measures had been verified by measurements of indoor radon concentration during various operating modes. Radon levels in all habitable rooms had been successfully reduced below the action level for existing houses 400 Bq/m{sup 3}. These results indicate that even in houses with extremely high indoor radon concentrations effective reduction of indoor radon is possible supposing that only effective measures are applied and their design takes into account specific soil and house characteristics. (authors)

  12. Novel inorganic nanomaterials generated with highly concentrated sunlight

    Science.gov (United States)

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

    2008-08-01

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

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

    Science.gov (United States)

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

    2015-05-01

    Highly spatially resolved mixing ratios of benzene and toluene, nitrogen oxides (NOx) and ozone (O3) were measured in the atmospheric boundary layer above Greater London during the period 24 June to 9 July 2013 using a Dornier 228 aircraft. Toluene and benzene were determined in situ using a proton transfer reaction mass spectrometer (PTR-MS), NOx by dual-channel NOx chemiluminescence and O3 mixing ratios by UV absorption. Average mixing ratios observed over inner London at 360 ± 10 m a.g.l. were 0.20 ± 0.05, 0.28 ± 0.07, 13.2 ± 8.6, 21.0 ± 7.3 and 34.3 ± 15.2 ppbv for benzene, toluene, NO, NO2 and NOx respectively. Linear regression analysis between NO2, benzene and toluene mixing ratios yields a strong covariance, indicating that these compounds predominantly share the same or co-located sources within the city. 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 ± 0.5 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 in the mid-afternoon for ozone (~ 40 ppbv O3), all at 360 ± 10 m a.g.l.

  14. Mapping Global Atmospheric CO2 Concentration at High Spatiotemporal Resolution

    Directory of Open Access Journals (Sweden)

    Yingying Jing

    2014-11-01

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

  15. 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)

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

    Science.gov (United States)

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

    2012-12-01

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

  17. Molecular Origin of Thermal Diffusion in Benzene+Cyclohexane Mixtures

    International Nuclear Information System (INIS)

    The isotope effect in thermal diffusion (Soret effect) of benzene+cyclohexane mixtures has been investigated by a holographic grating technique. The Soret coefficient can be split into additive contributions. One contribution, the isotope effect, stems from the differences of both mass and moment of inertia, and is independent of composition. An additional ''chemical'' contribution depends on concentration and even changes its sign at a benzene mole fraction xbenz?0.7 . The mass effect is in agreement with molecular dynamics calculations: the heavier component migrates to the cold side

  18. Molecular origin of thermal diffusion in benzene + cyclohexane mixtures.

    Science.gov (United States)

    Debuschewitz, C; Köhler, W

    2001-07-30

    The isotope effect in thermal diffusion (Soret effect) of benzene+cyclohexane mixtures has been investigated by a holographic grating technique. The Soret coefficient can be split into additive contributions. One contribution, the isotope effect, stems from the differences of both mass and moment of inertia, and is independent of composition. An additional "chemical" contribution depends on concentration and even changes its sign at a benzene mole fraction x(benz) approximately 0.7. The mass effect is in agreement with molecular dynamics calculations: the heavier component migrates to the cold side. PMID:11497788

  19. 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

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

    Scientific Electronic Library Online (English)

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

    2010-12-01

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

  1. 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)

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

    Science.gov (United States)

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

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

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

    Science.gov (United States)

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

    2013-12-01

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

  4. Characterization of blood donors with high haemoglobin concentration

    DEFF Research Database (Denmark)

    Magnussen, K; Hasselbalch, H C

    2013-01-01

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

  5. Concentration

    Science.gov (United States)

    2011-08-11

    This is the NCTM Android app of their familiar on line Illuminations game, "Concentration" ( cataloged separately ) which challenges a user to match whole numbers, shapes, fractions, or multiplication facts to equivalent representations. This game can be played by one or two players taking turns and can be played in clear pane mode, or for added challenge, with the windows closed.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-11-15

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

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

    International Nuclear Information System (INIS)

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

  8. Outdoor and indoor benzene evaluation by GC-FID and GC-MS/MS.

    Science.gov (United States)

    Sousa, José A; Domingues, Valentina F; Rosas, Mónica S; Ribeiro, Susana O; Alvim-Ferraz, Conceiçao M; Delerue-Matos, Cristina F

    2011-01-01

    The evaluation of benzene in different environments such as indoor (with and without tobacco smoke), a city area, countryside, gas stations and near exhaust pipes from cars running on different types of fuels was performed. The samples were analyzed using gas chromatography (GC) with flame ionization detection (FID) and tandem mass spectrometric detection (MS/MS) (to confirm the identification of benzene in the air samples). Operating conditions for the GC-MS analysis were optimized as well as the sampling and sample preparation. The results obtained in this work indicate that i) the type of fuel directly influences the benzene concentration in the air. Gasoline with additives provided the highest amount of benzene followed by unleaded gasoline and diesel; ii) the benzene concentration in the gas station was always higher than the advisable limit established by law (5 ?g m?³) and during the unloading of gasoline the achieved concentration was 8371 ?g m?³; iii) the data from the countryside (Taliscas) and the urban city (Matosinhos) were below 5 ?g m?³ except 5 days after a fire on a petroleum refinery plant located near the city; iv) it was proven that in coffee shops where smoking is allowed the benzene concentration is higher (6 ?g m?³) than in coffee shops where this is forbidden (4 ?g m?³). This method may also be helpful for environmental analytical chemists who use GC-MS/MS for the confirmation or/and quantification of benzene. PMID:21240706

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

    Science.gov (United States)

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

    2010-07-01

    Because crude oil and refined petroleum products can contain benzene and benzene is considered a known carcinogen by numerous independent and governmental agencies, including the International Agency for Cancer Research, the petroleum industry has implemented exposure control programs for decades. As part of the benzene control programs, significant exposure assessments have been performed; both qualitatively and through quantitative measurements. In this study, we evaluated the airborne concentrations of benzene and their variability over time at the ExxonMobil refinery in Beaumont, TX between 1976 and 2007. The results of 5854 personal air samples are included in this analysis; 3761 were considered non-task (> or =180 min) personal samples, and 2093 were considered task-related (benzene air concentrations: coker (n=146, mean=0.014 ppm, SD=0.036), lube extraction unit (n=31, meanbenzene air concentration was 1.4 ppm during routine operations. The most frequently sampled task during routine operations was blinding and breaking, and the mean benzene air concentrations associated with this task were statistically higher in the reformer area of the refinery (n=311, mean=3.2 ppm, SD=7.9) than in all other areas (n=200, mean=0.92 ppm, SD=3.1). However, task-related exposures were found to be statistically similar across job categories for a given task. This study thus provides a task-focused analysis for occupational exposure to benzene during refinery operations, and will be useful for understanding exposures at this refinery. PMID:20494616

  10. Breath and blood levels of benzene, toluene, cumene and styrene in non-occupational exposure.

    Science.gov (United States)

    Brugnone, F; Perbellini, L; Faccini, G B; Pasini, F; Maranelli, G; Romeo, L; Gobbi, M; Zedde, A

    1989-01-01

    Benzene, toluene, cumene and styrene were measured in the breath and blood of two groups of individuals. The first group included individuals belonging to a hospital staff, the second group included chemical workers who were not exposed to the abovementioned chemicals. The chemical workers were examined in plant infirmaries on the morning before the start of the workshift, and the hospital staff in the hospital infirmaries. One environmental air sample was taken in the infirmaries for each individual at the moment of the biological samplings. The environmental concentrations of benzene and styrene were significantly higher in the infirmaries of the chemical plant than in the infirmaries of the hospital. On the other hand, the environmental concentrations of toluene and cumene were not significantly different in the plant infirmaries and in the hospital infirmaries. In the hospital staff the alveolar concentrations of benzene, toluene and styrene were significantly lower than those in the chemical workers. In the hospital staff the blood concentrations of benzene, toluene and styrene were not significantly different from those in the chemical workers. Only the blood cumene concentration was significantly higher in the chemical workers. In hospital staff, smokers showed alveolar and blood concentrations of benzene and toluene that were significantly higher than those measured in the non smoker hospital staff. With reference to chemical workers, only alveolar benzene concentration was significantly higher in smokers than in non smokers.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2707867

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-10-15

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

  12. Dish-based high concentration PV system with Köhler optics.

    Science.gov (United States)

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

    2014-03-10

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

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

    Science.gov (United States)

    Mobrem, M.

    1985-01-01

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

  14. Wide acceptance angle, high concentration ratio, optical collector

    Science.gov (United States)

    Kruer, Mark A. (Inventor)

    1991-01-01

    A cassegrain optical system provides improved collection of off-axis light yet is still characterized by a high concentration ratio. The optical system includes a primary mirror for collecting incoming light and reflecting the light to a secondary mirror which, in turn, reflects the light to a solar cell or other radiation collection device. The primary mirror reflects incoming on-axis light onto an annular section of the secondary mirror and results in the reflection of a substantial amount of incoming off-axis light onto the remainder of the secondary mirror. Thus light which would otherwise be lost to the system will be captured by the collector. Furthermore, the off-axis sections of the secondary mirror may be of a different geometrical shape than the on-axis annular section so as to optimize the amount of off-axis light collected.

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

    Directory of Open Access Journals (Sweden)

    Oren Aharon

    2008-04-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-09-26

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

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

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Scharlack, R.S.; Moffat, A.

    1983-08-01

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

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

    Science.gov (United States)

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

    2013-06-01

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

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

    DEFF Research Database (Denmark)

    Frederiksen, H; SØrensen, K

    2012-01-01

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

  2. Identification of putative benzene-degrading bacteria in methanogenic enrichment cultures.

    Science.gov (United States)

    Sakai, Nahoko; Kurisu, Futoshi; Yagi, Osami; Nakajima, Fumiyuki; Yamamoto, Kazuo

    2009-12-01

    Anaerobic benzene-degrading enrichment cultures performing methanogenesis were obtained from non-contaminated lotus field soil. Stable isotope probing with 13C benzene was used to detect the bacteria that were involved in benzene degradation. Denaturing gradient gel electrophoresis (DGGE) of fractionated samples exhibited an obvious shift of some DGGE bands to a heavier DNA fraction. An almost full-length 16S rRNA gene sequence corresponding to the DGGE band, namely Hasda-A, was obtained by constructing a clone library of the heavier fraction. The Hasda-A sequence showed only 85.1% identity with the closest identified bacterium, Syntrophus gentianae. Hasda-A may be an important bacterium involved in the initial steps of benzene degradation under methanogenic conditions, as it was the most prominent bacterium that assimilated labeled benzene early in the process of benzene degradation. A primer set was designed to quantify the gene copies of Hasda-A by quantitative PCR. Hasda-A was present at a concentration of (3.5+/-0.8) x 10(6) copies/mL and represented 8.4% of gene copies among bacteria in the enrichment culture. The enrichment culture consisted of three dominant bacterial groups: Hasda-A and both aceticlastic and hydrogenotrophic methanogens. Methane is believed to be produced from benzene by the sequential degradation of benzene by fermenting bacteria, hydrogen-producing acetogens, and methanogens. PMID:19914583

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

    International Nuclear Information System (INIS)

    Highlights: • Co3O4 nanoparticles were introduced as a novel SPME fiber coating. • The fiber was evaluated for the extraction of BTEX in combination with GC–MS. • The fiber showed extraction efficiencies better than a PDMS fiber toward BTEX. • The fiber was successfully applied to the determination of BTEX in real samples. - Abstract: In this work cobalt oxide nanoparticles were introduced for preparation of a novel solid phase microextraction (SPME) fiber coating. Chemical bath deposition (CBD) technique was used in order for synthesis and immobilization of the Co3O4 nanomaterials on a Pt wire for fabrication of SPME fiber. The prepared cobalt oxide coating was characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The fiber was evaluated for the extraction of benzene, toluene, ethylbenzene and xylene (BTEX) in combination with GC–MS. A simplex optimization method was used to optimize the factors affecting the extraction efficiency. Under optimized conditions, the proposed fiber showed extraction efficiencies comparable to those of a commercial polydimethylsiloxane (PDMS) fiber toward the BTEX compounds. The repeatability of the fiber and its reproducibility, expressed as relative standard deviation (RSD), were lower than about 11%. No significant change was observed in the extraction efficiency of the new SPME fiber after over 50 extractions. The fiber was successfully applied to the determination of BTEX compounds in real samples. The proposed nanostructure cobalt oxide fiber is a promising alternative to the commercial fibers as it is robust, inexpensive and easily prepared

  4. 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

  5. Cylindrically symmetric Fresnel lens for high concentration photovoltaic

    Science.gov (United States)

    Hung, Yu-Ting; Su, Guo-Dung

    2009-08-01

    High concentration photovoltaic (HCPV) utilizes point-focus cost-effective plastic Fresnel lens. And a millimeter-sized Ill-V compound multi-junction solar cell is placed underneath focusing optics which can achieve cell efficiency potential of up to 40.7 %. The advantage of HCPV makes less solar cell area and higher efficiency; however, the acceptance angle of HCPV is about +/-1°, which is very small and the mechanical tracking of the sun is necessary. In order to reduce the power consumption and the angle tracking error of tracking systems, a light collector model with larger acceptance angle is designed with ZEMAX®. In this model, the original radially symmetric Fresnel lens of HCPV is replaced by cylindrically symmetric Fresnel lens and a parabolic reflective surface. Light is collected in two dimensions separately. And a couple of lenses and a light pipe are added before the solar cell chip in order to collect more light when sun light deviates from incident angle of 00. An acceptance angle of +/-10° is achieved with GCR 400.

  6. High resolution imaging of intracellular oxygen concentration by phosphorescence lifetime.

    Science.gov (United States)

    Kurokawa, Hiromi; Ito, Hidehiro; Inoue, Mai; Tabata, Kenji; Sato, Yoshifumi; Yamagata, Kazuya; Kizaka-Kondoh, Shinae; Kadonosono, Tetsuya; Yano, Shigenobu; Inoue, Masahiro; Kamachi, Toshiaki

    2015-01-01

    Optical methods using phosphorescence quenching by oxygen are suitable for sequential monitoring and non-invasive measurements for oxygen concentration (OC) imaging within cells. Phosphorescence intensity measurement is widely used with phosphorescent dyes. These dyes are ubiquitously but heterogeneously distributed inside the whole cell. The distribution of phosphorescent dye is a major disadvantage in phosphorescence intensity measurement. We established OC imaging system for a single cell using phosphorescence lifetime and a laser scanning confocal microscope. This system had improved spatial resolution and reduced the measurement time with the high repetition rate of the laser. By the combination of ubiquitously distributed phosphorescent dye with this lifetime imaging microscope, we can visualize the OC inside the whole cell and spheroid. This system uses reversible phosphorescence quenching by oxygen, so it can measure successive OC changes from normoxia to anoxia. Lower regions of OC inside the cell colocalized with mitochondria. The time-dependent OC change in an insulin-producing cell line MIN6 by the glucose stimulation was successfully visualized. Assessing the detailed distribution and dynamics of OC inside cells achieved by the presented system will be useful to understanding a physiological and pathological oxygen metabolism. PMID:26065366

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

    Directory of Open Access Journals (Sweden)

    J. H. Seinfeld

    2007-07-01

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

  8. Hydrogen bonding in the benzene-ammonia dimer

    Science.gov (United States)

    Rodham, David A.; Suzuki, Sakae; Suenram, Richard D.; Lovas, Frank J.; Dasgupta, Siddharth; Goddard, William A., III; Blake, Geoffrey A.

    1993-01-01

    High-resolution optical and microwave spectra of the gas-phase benzene-ammonia dimer were obtained, showing that the ammonia molecule resides above the benzene plane and undergoes free, or nearly free, internal rotation. To estimate the binding energy (De) and other global properties of the intermolecular potential, theoretical calculations were performed for the benzene-ammonia dimer, using the Gaussian 92 (Fritsch, 1992) program at the MP2/6-31G** level. The predicted De was found to be at the lowest end of the range commonly accepted for hydrogen bonding and considerably below that of C6H6-H2O, consistent with the gas-phase acidities of ammonia and water. The observed geometry greatly resembles the amino-aromatic interaction found naturally in proteins.

  9. Benzene formation in the inner regions of protostellar disks

    CERN Document Server

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

    2006-01-01

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

  10. 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

  11. Slow Neutron Scattering by Benzene

    International Nuclear Information System (INIS)

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

  12. Review of quantitative surveys of the length and stability of MTBE, TBA, and benzene plumes in groundwater at UST sites.

    Science.gov (United States)

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

    2015-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-04-01

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

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

    OpenAIRE

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

    2009-01-01

    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. ...

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

    International Nuclear Information System (INIS)

    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 adduon 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

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

    Directory of Open Access Journals (Sweden)

    Pavle Randjelovic

    2001-03-01

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

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

    DEFF Research Database (Denmark)

    Arayasiri, Manaswee; Mahidol, Chulabhorn

    2010-01-01

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

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

    Science.gov (United States)

    Irons, R D; Neptun, D A

    1980-10-01

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

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

    Czech Academy of Sciences Publication Activity Database

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

    2014-01-01

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

  20. MEASUREMENT OF BENZENE OXIDE IN THE BLOOD OF RATS FOLLOWING ADMINISTRATION OF BENZENE

    Science.gov (United States)

    Although it is generally assumed that metabolism of benzene proceeds through an initial step involving oxidation to benzene oxide (BO) by CYP450 in the liver, the production of BO has never been unambiguously confirmed in animals dosed with benzene. Furthermore, prevailing hypo...

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

    Directory of Open Access Journals (Sweden)

    Flynn John T

    2008-02-01

    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.

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

    Science.gov (United States)

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

    2011-07-01

    The conversion of sunlight into electricity has been dominated by photovoltaic and solar thermal power generation. Photovoltaic cells are deployed widely, mostly as flat panels, whereas solar thermal electricity generation relying on optical concentrators and mechanical heat engines is only seen in large-scale power plants. Here we demonstrate a promising flat-panel solar thermal to electric power conversion technology based on the Seebeck effect and high thermal concentration, thus enabling wider applications. The developed solar thermoelectric generators (STEGs) achieved a peak efficiency of 4.6% under AM1.5G (1 kW m(-2)) conditions. The efficiency is 7-8 times higher than the previously reported best value for a flat-panel STEG, and is enabled by the use of high-performance nanostructured thermoelectric materials and spectrally-selective solar absorbers in an innovative design that exploits high thermal concentration in an evacuated environment. Our work opens up a promising new approach which has the potential to achieve cost-effective conversion of solar energy into electricity. PMID:21532584

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

    Science.gov (United States)

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

    2011-07-01

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

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

    LENUS (Irish Health Repository)

    McNally, P

    2012-02-01

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

  5. Anaerobic Benzene Oxidation via Phenol in Geobacter metallireducens

    OpenAIRE

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

    2013-01-01

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

  6. Electrochemical-driven water splitting catalyzed by a water-soluble cobalt(II) complex supported by N,N?-bis(2?-pyridinecarboxamide)-1,2-benzene with high turnover frequency

    Science.gov (United States)

    Wang, Zhuo-Qiang; Tang, Ling-Zhi; Zhang, Yun-Xiao; Zhan, Shu-Zhong; Ye, Jian-Shan

    2015-08-01

    The oxidation and reduction of water is a key challenge in the production of chemical fuels from electricity. Reported here is a soluble cobalt (II) complex, [Co(bpbH2)Cl2] 1 (bpbH2: N,N?-bis(2?-pyridinecarboxamide)-1,2-benzene), a highly active homogeneous electrocatalyst for both electrolytic water oxidation and reduction in purely aqueous solution. Electrochemical studies indicate that the catalyst is a water-soluble molecular species, that is among the most rapid homogeneous catalysts for water oxidation, with a turnover frequency of ?81.54 s-1 (at pH 8.6, the lowest pH among those of any reported electrocatalysts) at an overpotential of 560 mV. 1 also can catalyze hydrogen evolution from water with a TOF of 376 mol of hydrogen per mole of catalyst per hour at an overpotential of 687.6 mV (pH 7.0). This is attributed to the planar ligand (bpbH2), that coordinates strongly through four nitrogen atoms to the cobalt center, leaving two Cl- ions in axial position and making the Cl- ion ionize in organic solvents or water, and can stabilize both the high and low oxidation states of cobalt well.

  7. Dynamical and structural properties of benzene in supercritical water

    Science.gov (United States)

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

    2004-12-01

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

  8. Dynamical and structural properties of benzene in supercritical water.

    Science.gov (United States)

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

    2004-12-01

    We have employed an anisotropic united atom model of benzene (R. O. Contreras, Ph.D. thesis, Universitat Rovira i Virgili 2002) that reproduces the quadrupolar moment of this molecule through the inclusion of seven point charges. We show that this kind of interaction is required to reproduce the solvation of these molecules in supercritical water. We have computed self-diffusion coefficient and Maxwell-Stefan coefficients as well as the shear viscosity for the mixture water-benzene at supercritical conditions. A strong density and composition dependence of these properties is observed. In addition, our simulations are in qualitative agreement with the experimental evidence that, at medium densities (0.6 g/cm(3) and 673 K), almost half of the benzene molecules have one hydrogen bond with water molecules. We also observe that these bonds are longer lived than the corresponding hydrogen bonds between water molecules. Similarly, we obtain an important reduction of the dielectric constant of the mixture with the increment of the amount of benzene molecules at medium and high densities. PMID:15549940

  9. 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.)

  10. Thermodynamic Limitations of Photosynthetic Water Oxidation at High Proton Concentrations*

    OpenAIRE

    Zaharieva, Ivelina; Wichmann, Jo?rg M.; Dau, Holger

    2011-01-01

    In oxygenic photosynthesis, solar energy drives the oxidation of water catalyzed by a Mn4Ca complex bound to the proteins of Photosystem II. Four protons are released during one turnover of the water oxidation cycle (S-state cycle), implying thermodynamic limitations at low pH. For proton concentrations ranging from 1 nm (pH 9) to 1 mm (pH 3), we have characterized the low-pH limitations using a new experimental approach: a specific pH-jump protocol combined with time-resolved measurement of ...

  11. 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)

  12. High Energy Density Lithium Air Batteries for Oxygen Concentrators Project

    National Aeronautics and Space Administration — For NASA's Exploration Medical Capabilities mission, extremely high specific energy power sources, with specific energy over 2000 Wh/kg, are urgently sought after....

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

    Directory of Open Access Journals (Sweden)

    Najmaldin Saki

    2013-07-01

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

  14. Water environment conservation in a closed water body by high concentrated oxygen water.

    Science.gov (United States)

    Imai, Tsuyoshi; Watanapokasin, Ramida; Reungsang, Alissara; Sekine, Masahiko; Higuchi, Takaya

    2008-01-01

    In this study, the method of using high concentrated oxygen water to purify the bottom sediment was confirmed to be effective. The high concentrated oxygen dissolver was developed and the lab scale experiment was performed. High rate, high efficiency oxygen dissolver was developed, the optimum running condition of the apparatus and the method of producing high concentrated oxygen water was discussed and determined in this study. In addition, the effective prevention of phosphorus release from anaerobic bottom sediment was also studied. As a result, it is found that high concentrated oxygen water was effective for prevention of phosphorus release from anaerobic bottom sediment. On the basis of the fundamental knowledge from the laboratory-scale study, pilot scale apparatus was set up and the pilot study was carried out. It is showed that the introduction of high concentrated oxygen water did not destroy the thermocline of dam reservoir. PMID:19092209

  15. Titanium doped silicon layers with very high concentration

    International Nuclear Information System (INIS)

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

  16. Thermodynamic limitations of photosynthetic water oxidation at high proton concentrations.

    Science.gov (United States)

    Zaharieva, Ivelina; Wichmann, Jörg M; Dau, Holger

    2011-05-20

    In oxygenic photosynthesis, solar energy drives the oxidation of water catalyzed by a Mn(4)Ca complex bound to the proteins of Photosystem II. Four protons are released during one turnover of the water oxidation cycle (S-state cycle), implying thermodynamic limitations at low pH. For proton concentrations ranging from 1 nm (pH 9) to 1 mm (pH 3), we have characterized the low-pH limitations using a new experimental approach: a specific pH-jump protocol combined with time-resolved measurement of the delayed chlorophyll fluorescence after nanosecond flash excitation. Effective pK values were determined for low-pH inhibition of the light-induced S-state transitions: pK(1)=3.3 ± 0.3, pK(2)=3.5 ± 0.2, and pK(3)?pK(4)=4.6 ± 0.2. Alkaline inhibition was not observed. An extension of the classical Kok model facilitated assignment of these four pK values to specific deprotonation steps in the reaction cycle. Our results provide important support to the extended S-state cycle model and criteria needed for assessment of quantum chemical calculations of the mechanism of water oxidation. They also imply that, in intact organisms, the pH in the lumen compartment can hardly drop below 5, thereby limiting the ?pH contribution to the driving force of ATP synthesis. PMID:21464129

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

    OpenAIRE

    Kaneva Anastasiya M.; Potolitsyna Natalya N.; Bojko Evgeny R.

    2013-01-01

    The aim of this study was to determine apolipoprotein (apo) E concentration in the high-density lipoprotein (HDL) fractions of normolipidemic subjects. ApoE concentrations in total blood plasma and HDL fractions were measured by an immunoturbidimetric method. We observed that the quantitative distribution of apoE among different lipoprotein classes depends on the total plasma apoE concentration: at low total plasma apoE concentration, a substantial amount of apoE was associated with HDL...

  18. High Precision Fe Isotope Analysis in low Concentration Samples by High Resolution MC-ICPMS

    Science.gov (United States)

    Chung, C.; Wu, J.; You, C.

    2009-12-01

    Iron availability has been shown to be the main limitation factor for phytoplankton growth in the ocean. However, due to the limitation of analytical technique, the database of dissolved Fe concentrations and isotope ratio distribution in the ocean is still very limited. In particular, the iron sources to the ocean remain uncertain. Aeolian dust from the continental is considered as the primary source, also the digenetic dissolution at the continental margins is proposed to contribute significant portion of iron content of the sea surface water. The field of Fe isotope geochemistry has seen important developments in methodology and scope since the advent of Multi-Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS). Although increasing the number of replicates in High Resolution MC-ICPMS reduces the uncertainty related to instability in instrumental mass bias and counting statistics, many other parameters include mass fractionation during column separation, matrix effect in ICPMS analysis and the presence of isobaric interferences can affect the precision and accuracy of Fe isotopic analyses. In this study, a high precision analytical method of Fe isotope measurement for low concentration samples was developed using HR-MC-ICPMS. Several parameters that may affect the accuracy and precision of 56Fe/54Fe result such as background, instrumental mass discrimination, isobaric interferences, type of introduction system and acid molarity were identified and evaluated. External precisions better than 0.04‰ for ?56Fe can be achieve using only 10ng of iron sample with APEX and X-cone as introduction system. Significant improvement in terms of sample size was made. This method can be applied on very low concentration samples such as coral and seawater.

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

    OpenAIRE

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

    2013-01-01

    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 ...

  20. High plasma uric acid concentration: causes and consequences

    Directory of Open Access Journals (Sweden)

    de Oliveira Erick

    2012-04-01

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

  1. Deep Sea Memory of High Atmospheric CO2 Concentration

    Science.gov (United States)

    Mathesius, Sabine; Hofmann, Matthias; Caldeira, Ken; Schellnhuber, Hans Joachim

    2015-04-01

    Carbon dioxide removal (CDR) from the atmosphere has been proposed as a powerful measure to mitigate global warming and ocean acidification. Planetary-scale interventions of that kind are often portrayed as "last-resort strategies", which need to weigh in if humankind keeps on enhancing the climate-system stock of CO2. Yet even if CDR could restore atmospheric CO2 to substantially lower concentrations, would it really qualify to undo the critical impacts of past emissions? In the study presented here, we employed an Earth System Model of Intermediate Complexity (EMIC) to investigate how CDR might erase the emissions legacy in the marine environment, focusing on pH, temperature and dissolved oxygen. Against a background of a world following the RCP8.5 emissions path ("business-as-usual") for centuries, we simulated the effects of two massive CDR interventions with CO2 extraction rates of 5 GtC yr-1 and 25 GtC yr-1, respectively, starting in 2250. We found that the 5 GtC yr-1 scheme would have only minor ameliorative influence on the oceans, even after several centuries of application. By way of contrast, the extreme 25 GtC yr-1 scheme eventually leads to tangible improvements. However, even with such an aggressive measure, past CO2 emissions leave a substantial legacy in the marine environment within the simulated period (i.e., until 2700). In summary, our study demonstrates that anthropogenic alterations of the oceans, caused by continued business-as-usual emissions, may not be reversed on a multi-centennial time scale by the most aspirational geoengineering measures. We also found that a transition from the RCP8.5 state to the state of a strong mitigation scenario (RCP2.6) is not possible, even under the assumption of extreme extraction rates (25 GtC yr-1). This is explicitly demonstrated by simulating additional scenarios, starting CDR already in 2150 and operating until the atmospheric CO2 concentration reaches 280 ppm and 180 ppm, respectively. The simulated massive CDR interventions eventually bring down the global mean pH value to the RCP2.6 level, yet cannot restore a similarly homogenous distribution - while the pH of the upper ocean returns to the preindustrial value or even exceed it (in the 180 ppm scenario), the deep ocean remains acidified. The deep ocean is out of contact with the atmosphere and therefore unreachable by atmospheric CDR. Our results suggest that the proposition that the marine consequences of early emissions reductions are comparable to those of delayed reductions plus CDR is delusive and that a policy that allows for emitting CO2 today in the hopes of removing it tomorrow is bound to generate substantial regrets.

  2. Solar Thermal Collectors at High Latitudes : Design and performance of non-tracking concentrators

    OpenAIRE

    Adsten, Monika

    2002-01-01

    Solar thermal collectors at high latitudes have been studied, with emphasis on concentrating collectors. A novel design of concentrating collector, the Maximum Reflector Collector (MaReCo), especially designed for high latitudes, has been investigated optically and thermally. The MaReCo is an asymmetrical compound parabolic concentrator with a bi-facial absorber. The collector can be adapted to various installation conditions, for example stand-alone, roof- or wall mounted. MaReCo prototypes ...

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

    OpenAIRE

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

    2002-01-01

    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...

  4. 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

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

    Directory of Open Access Journals (Sweden)

    F. A. Halim

    2013-10-01

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

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

    Science.gov (United States)

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

    2015-04-01

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

  7. 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

  8. High concentration of deuterium in palladium from plasma ion implantation

    International Nuclear Information System (INIS)

    Based on a theoretical calculation, a new scheme to increase deuterium density in palladium over its initial value is presented. This deuterium enrichment scheme makes use of plasma ion implantation. A cylindrical palladium rod (target) preloaded with deuterium atoms, coated with a diffusion-barrier material, is immersed in a deuterium plasma. The palladium rod is connected to a high-power modulator which provides a series of negative-voltage pulses. During these negative pulses, deuterium ions fall into the target, penetrate the diffusion barrier, and are implanted inside the palladium. For reasonable system parameters allowed by present technology, it is found from theoretical calculations that the saturation deuterium density after prolonged ion implantation can be several times the palladium atomic number density. Assuming an initial deuterium density, n0=4x1022 cm-3, it is also found that the deuterium density in palladium can triple its original value within a few days of the ion implantation for a reasonable target size. Because of the small diffusion coefficient in palladium, the incoming ions do not diffuse quickly inward, thereby accumulating near the target surface at the beginning of the implantation

  9. Efficient purification and concentration of viruses from a large body of high turbidity seawater

    Science.gov (United States)

    Sun, Guowei; Xiao, Jinzhou; Wang, Hongming; Gong, Chaowen; Pan, Yingjie; Yan, Shuling; Wang, Yongjie

    2014-01-01

    Marine viruses are the most abundant entities in the ocean and play crucial roles in the marine ecological system. However, understanding of viral diversity on large scale depends on efficient and reliable viral purification and concentration techniques. Here, we report on developing an efficient method to purify and concentrate viruses from large body of high turbidity seawater. The developed method characterizes with high viral recovery efficiency, high concentration factor, high viral particle densities and high-throughput, and is reliable for viral concentration from high turbidity seawater. Recovered viral particles were used directly for subsequent analysis by epifluorescence microscopy, transmission electron microscopy and metagenomic sequencing. Three points are essential for this method:•The sampled seawater (>150 L) was initially divided into two parts, water fraction and settled matter fraction, after natural sedimentation.•Both viruses in the water fraction concentrated by tangential flow filtration (TFF) and viruses isolated from the settled matter fraction were considered as the whole viral community in high turbidity seawater.•The viral concentrates were re-concentrated by using centrifugal filter device in order to obtain high density of viral particles.

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

    Directory of Open Access Journals (Sweden)

    Sulaiman Siti

    2011-08-01

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

  11. The inorganic analogues of carbo-benzene

    Science.gov (United States)

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

    2014-08-01

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

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

    Science.gov (United States)

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

    2010-01-01

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

  13. 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).

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

    Science.gov (United States)

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

    2015-02-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-05-26

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

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

    DEFF Research Database (Denmark)

    Kosiorowska, Anna Katarzyna; Puggaard, Liselotte

    2011-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

    Fujii, S.; Beutler, E.

    1985-01-01

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

  19. Impact of High Concentration Solutions on Hydraulic Properties of Geosynthetic Clay Liner Materials

    OpenAIRE

    Lei Liu; Qiang Xue; Qian Zhang

    2012-01-01

    This study focuses on the impact of landfill high concentration solutions erosion on geosynthetic clay liner (GCL) materials permeability. The permeation tests on the GCL, submerged using different kinds of solutions with different concentrations, were carried out systematically by taking these chemical solutions as permeant liquids. Based on seasonal variations of ion concentrations in Chenjiachong landfill leachate (Wuhan Province), CaCl2, MgCl2, NaCl, and KCl were selected as chemical atta...

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

    OpenAIRE

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

    1991-01-01

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

  1. Effect of Carrier Concentration Dependant Mobility on the Performance of High Electron Mobility Transistors

    OpenAIRE

    Erol, Mustafa

    2001-01-01

    The influence of the sheet carrier concentration dependence on mobility on the performance of High Electron Mobility Transistor (HEMT) structures is theoretically modeled. The model basically takes into account both the drift and diffusion part of the overall drain current. The normalised drain current and normalised transconductance are found to be greatly affected by the carrier concentration dependant mobility.

  2. 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

  3. The leap-frog effect of ring currents in benzene.

    Science.gov (United States)

    Ligabue, Andrea; Soncini, Alessandro; Lazzeretti, Paolo

    2002-03-01

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

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

    Science.gov (United States)

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

    2005-08-01

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

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

    OpenAIRE

    M. Orikawa; H. Kamahara; Y. Atsuta; Daimon, H.

    2013-01-01

    Tomato and seaweed were produced by utilizing CO2 and heat discharged from power generation using biogas in Toyogawa biomass park, Japan. The biogas was obtained by anaerobic digestion with hydrothermal treatment. The hydrothermal treatment was applied to the high concentrated sewage sludge (22 % total solids (TS) dewatered sludge). The purpose of this study is to clarify the effect of hydrothermal treatment on the qualities of high concentrated sewage sludge, by analyzing particulate organic...

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

    Energy Technology Data Exchange (ETDEWEB)

    Vasconcellos, L.M.H.; Lauria, O.C.; Velasco, A.F. [Instituto de Radioprotecao e Dosimetria (IRD), Rio de Janeiro, RJ (Brazil)

    2000-07-01

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

  7. 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

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

    Science.gov (United States)

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

    1995-08-01

    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.

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

    Scientific Electronic Library Online (English)

    Karina, Kovalchuk; Irina, Masalova.

    Full Text Available 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

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

    Science.gov (United States)

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

    2006-08-01

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

  11. Microbial respiration and natural attenuation of benzene contaminated soils investigated by cavity enhanced Raman multi-gas spectroscopy.

    Science.gov (United States)

    Jochum, Tobias; Michalzik, Beate; Bachmann, Anne; Popp, Jürgen; Frosch, Torsten

    2015-05-01

    Soil and groundwater contamination with benzene can cause serious environmental damage. However, many soil microorganisms are capable to adapt and are known to strongly control the fate of organic contamination. Innovative cavity enhanced Raman multi-gas spectroscopy (CERS) was applied to investigate the short-term response of the soil micro-flora to sudden surface contamination with benzene regarding the temporal variations of gas products and their exchange rates with the adjacent atmosphere. (13)C-labeled benzene was spiked on a silty-loamy soil column in order to track and separate the changes in heterotrophic soil respiration - involving (12)CO2 and O2- from the natural attenuation process of benzene degradation to ultimately form (13)CO2. The respiratory quotient (RQ) decreased from a value 0.98 to 0.46 directly after the spiking and increased again within 33 hours to a value of 0.72. This coincided with the maximum (13)CO2 concentration rate (0.63 ?mol m(-2) s(-1)), indicating the highest benzene degradation at 33 hours after the spiking event. The diffusion of benzene in the headspace and the biodegradation into (13)CO2 were simultaneously monitored and 12 days after the benzene spiking no measurable degradation was detected anymore. The RQ finally returned to a value of 0.96 demonstrating the reestablished aerobic respiration. PMID:25751376

  12. 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

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

    Science.gov (United States)

    Taudien, Jerker Y.; Kern, Ludwig A.

    2013-09-01

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

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

    Science.gov (United States)

    Sarayu, K; Sandhya, S

    2012-12-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-03-20

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

  16. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    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

    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)

  18. Corrosion behaviour of stainless steels in flowing LBE at low and high oxygen concentration

    Energy Technology Data Exchange (ETDEWEB)

    Aiello, A. [ENEA C.R. Brasimone, Camugnano, BO 40032 (Italy); Azzati, M. [China Institute of Atomic Energy, 102413 Beijing (China); Benamati, G. [ENEA C.R. Brasimone, Camugnano, BO 40032 (Italy); Gessi, A. [ENEA C.R. Brasimone, Camugnano (Bolivia) 40032 (Italy)]. E-mail: alessandro.gessi@brasimone.enea.it; Long, B. [Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy)]. E-mail: long.bin@brasimone.enea.it; Scaddozzo, G. [China Institute of Atomic Energy, 102413 Beijing (China)

    2004-11-01

    The corrosion behaviours of austenitic steel AISI 316L and martensitic steel T91 were investigated in flowing lead-bismuth eutectic (LBE) at 400 deg. C. The tests were performed in the LECOR and CHEOPE III loops, which stood for the low oxygen concentration and high oxygen concentration in LBE, respectively. The results obtained shows that steels were affected by dissolution at the condition of low oxygen concentration (C{sub [O{sub 2}]} = 10{sup -8}-10{sup -10} wt%) and were oxidized at the condition of high oxygen concentration (C{sub [O{sub 2}]} = 10{sup -5}-10{sup -6} wt%). The oxide layers detected are able to protect the steels from dissolution in LBE. Under the test condition adopted, the austenitic steel behaved more resistant to corrosion induced by LBE than the martensitic steel.

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

    OpenAIRE

    Duong, Van; Gerardo Diaz

    2014-01-01

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

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

    OpenAIRE

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

    1997-01-01

    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...

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

    Science.gov (United States)

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

    2014-11-01

    Nutrient concentrations in the Mississippi River have increased dramatically since the 1950s, and high frequency measurements on nitrate concentration are required for accurate load estimations and examinations on nitrate transport and transformation processes. This three year record of high temporal resolution (every 2-3 h) data clearly illustrates the importance of high frequency sampling in improving load estimates and resolving variations in nitrate concentration with river flow and tributary inputs. Our results showed large short-term (days to weeks) variations in nitrate concentration but with no diurnal patterns. A repeatable and pronounced seasonal pattern of nitrate concentration was observed, and showed gradual increases from the lowest values in September (during base-flow), to the highest in June - which was followed by a rapid decrease. This seasonal pattern was only moderately linked with water discharge, and more controlled by nitrogen transformation/export from watershed as well as mixing patterns of the two primary tributaries (the upper Mississippi and the Ohio Rivers), which have distinctly different nitrate concentrations and flow patterns. Based on continuous in situ flow measurements, we estimated 554-886 × 106 kg of nitrate-N was exported from the Mississippi River system during years 2004-2006, which was <9% and <16% lower than U.S. Geological Survey's (USGS) estimates using their LOADEST or composite methods, respectively. USGS methods generally overestimated nitrate loads during rising stages and underestimated the loads during falling stages. While changes in nitrate concentrations in large rivers are generally not as responsive to alterations in diurnal inputs and/or watershed hydrology as small rivers, high-frequency water quality sampling would help in monitoring short-term (days to weeks) variations in nutrient concentration patterns and thus improve the accuracy of nutrient flux estimates.

  2. Ferric citrate decreases ruminal hydrogen sulphide concentrations in feedlot cattle fed diets high in sulphate.

    Science.gov (United States)

    Drewnoski, Mary E; Doane, Perry; Hansen, Stephanie L

    2014-01-28

    Dissimilatory reduction of sulphate by sulphate-reducing bacteria in the rumen produces sulphide, which can lead to a build-up of the toxic gas hydrogen sulphide (H2S) in the rumen when increased concentrations of sulphate are consumed by ruminants. We hypothesised that adding ferric Fe would competitively inhibit ruminal sulphate reduction. The effects of five concentrations and two sources (ferric citrate or ferric ammonium citrate) of ferric Fe were examined in vitro (n 6 per treatment). Rumen fluid was collected from a steer that was adapted to a high-concentrate, high-sulphate diet (0·51 % S). The addition of either source of ferric Fe decreased (Psulphate control diet (0·46 % S) or the control diet plus ferric ammonium citrate at concentrations of 200, 300 or 400 mg Fe/kg diet DM. The inclusion of ferric Fe did not affect DM intake (P= 0·21). There was a linear (P< 0·01) decrease in the concentration of ruminal H2S as the addition of ferric Fe concentrations increased. Ferric citrate appears to be an effective way to decrease ruminal H2S concentrations, which could allow producers to safely increase the inclusion of ethanol co-products. PMID:23880397

  3. Denitrification of a landfill leachate with high nitrate concentration in an anoxic rotating biological contactor.

    Science.gov (United States)

    Cortez, Susana; Teixeira, Pilar; Oliveira, Rosário; Mota, Manuel

    2011-06-01

    The denitrification performance of a lab-scale anoxic rotating biological contactor (RBC) using landfill leachate with high nitrate concentration was evaluated. Under a carbon to nitrogen ratio (C/N) of 2, the reactor achieved N-NO(3)(-) removal efficiencies above 95% for concentrations up to 100 mg N-NO(3)(-) l(-1). The highest observed denitrification rate was 55 mg N-NO(3)(-) l(-1) h(-1) (15 g N-NO(3)(-) m(-2) d(-1)) at a nitrate concentration of 560 mg N-NO(3)(-) l(-1). Although the reactor has revealed a very good performance in terms of denitrification, effluent chemical oxygen demand (COD) concentrations were still high for direct discharge. The results obtained in a subsequent experiment at constant nitrate concentration (220 mg N-NO(3)(-) l(-1)) and lower C/N ratios (1.2 and 1.5) evidenced that the organic matter present in the leachate was non-biodegradable. A phosphorus concentration of 10 mg P-PO(4)(3-) l(-1) promoted autotrophic denitrification, revealing the importance of phosphorus concentration on biological denitrification processes. PMID:21153683

  4. 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)

  5. 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)

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2004-01-01

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

  8. Denitrification of a landfill leachate with high nitrate concentration in an anoxic rotating biological contactor

    OpenAIRE

    Cortez, Susana; Teixeira, P.; Oliveira, Rosa?rio; Mota, M.

    2011-01-01

    The denitrification performance of a lab-scale anoxic rotating biological contactor (RBC) using landfill leachate with high nitrate concentration was evaluated. Under a carbon to nitrogen ratio (C/N) of 2, the reactor achieved N-NO3 ? removal efficiencies above 95% for concentrations up to 100 mg N-NO3 ? l?1. The highest observed denitrification rate was 55 mg N-NO3 ? l?1 h?1 (15 g N-NO3 ? m?2 d?1) at a nitrate concentration of 560 mg N-NO3 ? l?1. Although the reactor ha...

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

    OpenAIRE

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

    2014-01-01

    Although the local application of mitomycin C may prevent epidural adhesion after laminectomy, mitomycin C can induce neurotoxicity in optic and acoustic nerves at high concentrations. To determine the safe concentration range for mitomycin C, cotton pads soaked with mitomycin C at different concentrations (0.1, 0.3, 0.5, and 0.7 mg/mL) were immediately applied for 5 minutes to the operation area of rats that had undergone laminectomy at L1. Rat sciatic nerves, instead of dorsal nerves, were ...

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

    Science.gov (United States)

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

    1997-12-01

    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.

  11. Removal of benzene from wastewater via Fenton pre-treatment followed by enzyme catalyzed polymerization.

    Science.gov (United States)

    Saha, Beeta; Taylor, K E; Bewtra, J K; Biswas, N

    2011-01-01

    This study investigated the feasibility of a two-step process for the removal of benzene from buffered synthetic wastewater. Benzene is outside the scope of enzymatic removal. In order to remove it from wastewater using enzyme, its pretreatment by modified Fenton reaction was employed to generate the corresponding phenolic compounds. In the first phase, the optimum pH, H2O2 and Fe2+ concentrations and reaction time for the Fenton reaction were determined to maximize the conversion of benzene to phenolic compounds without causing significant mineralization. The pretreatment process was followed by oxidative polymerization of the phenolic compounds catalyzed by a laccase from Trametes villosa. Factors of interest for the three-hour enzymatic treatment were pH and laccase concentration. Under optimum Fenton reaction conditions, 80% conversion of the initial benzene concentration was achieved, giving a mixture containing oxidative dimerization product (biphenyl) and hydroxylation products (phenol, catechol, resorcinol, benzoquinone and hydroquinone). Enzymatic removal of biphenyl and benzoquinone was not possible but 2.5 U/mL laccase was successful in removal of the rest of the phenolic PMID:21866766

  12. High Voltage Solar Concentrator Experiment with Implications for Future Space Missions

    Science.gov (United States)

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

    2004-01-01

    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.

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

    Science.gov (United States)

    Feuermann, Daniel; Gordon, Jeffrey M.

    1998-10-01

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

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

    Directory of Open Access Journals (Sweden)

    M. Orikawa

    2013-10-01

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

  15. Catalytic oxidation of benzene using mesoporous alpha-Mn2O3.

    Science.gov (United States)

    An, Hyung Bum; Kim, Ji Man; Jurng, Jongsoo; Bae, Gwi-Nam; Jeon, Jong-Ki; Park, Sung Hoon; Park, Young-Kwon

    2013-11-01

    The catalytic oxidation of benzene was carried out over mesoporous alpha-Mn2O3, MnOx/KIT-6, and bulk commercial Mn oxides (Mn2O3, MnO2, and MnO). The catalysts were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller analysis, and temperature-programmed reduction analysis. MnOx/KIT-6, prepared by impregnating MnOx on KIT-6, exhibited a low activity for the oxidation of benzene, whereas mesoporous alpha-Mn2O3, manufactured using KIT-6 as the template, showed a high activity. The order of the activities of bulk Mn oxides for benzene decomposition was shown to be Mn2O3 > MnO2 > MnO. Therefore, the high activity of mesoporous alpha-Mn2O3 is attributed to the uniform distribution of highly active Mn2O3 in the mesoporous structure. PMID:24245276

  16. 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.

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

    Science.gov (United States)

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

    2005-08-01

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

  18. Benzene degradation coupled with chlorate reduction in soil column study

    OpenAIRE

    Tan, N.C.G.; Doesburg, W.C.J., van; Langenhoff, A.A.M.; Stams, A. J. M.

    2006-01-01

    Perchlorate and chlorate are electron acceptors that during reduction result in the formation of molecular oxygen. The produced oxygen can be used for activation of anaerobic persistent pollutants, like benzene. In this study chlorate was tested as potential electron acceptor to stimulate benzene degradation in anoxic polluted soil column. A chlorate amended benzene polluted soil column was operated over a period of 500 days. Benzene was immediately degraded in the column after start up, and ...

  19. Hydrogen Absorption at Room Temperature in Nanoscale Titanium Benzene Complexes

    OpenAIRE

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

    2009-01-01

    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...

  20. Rheology Control of Highly Concentrated Mullite Suspensions with Polyelectrolyte for Robocasting

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-06-12

    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.

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

    Science.gov (United States)

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

    2015-01-01

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

  2. Use of Fixed-Film Bioreactors, in Situ Microcosms, and Molecular Biological Analyses to Evaluate Bioremediation of Chlorinated Benzenes By Indigenous Bacteria and a Bioaugmented Dechlorinating Consortium

    Science.gov (United States)

    Lorah, M. M.; Teunis, J. A.

    2014-12-01

    Evaluation of bioremediation is complicated by contaminant mixtures, high concentrations, variable site conditions, and multiple possible degradation pathways. In this study, fixed-film bioreactor experiments, in situ microcosms, and microbial analyses were utilized to evaluate both anaerobic and aerobic biodegradation processes for tri- and dichlorobenzene isomers, monochlorobenzene, and benzene in a wetland. Biofilm-based bioreactors provide a robust assessment tool because of their typically high degree of stability, even with major and repeated perturbations. Two bioreactor units seeded with an anaerobic dechlorinating consortium (WBC-2) and one unit seeded only with bacteria indigenous to the site were operated under flow-through conditions to compare biougmentation and natural attenuation. Electron donor levels were varied to fluctuate between anaerobic and aerobic conditions, and inflow concentrations of total chlorobenzenes were transitioned from 1-10 mg/L to 50-100 mg/L. Biodegradation resulted in removal efficiencies of 80 to 99 percent for the different compounds and inflow concentrations. Degradation efficiency in the native bioreactor was not impacted by cycling between anaerobic and aerobic conditions, although removal rates for monochlorobenzene and benzene increased under aerobic conditions. In situ microcosms were incubated below the wetland surface in sets of 3 treatments—unamended, biostimulated (lactate addition), and bioaugmented (WBC-2 and lactate). Additional treatment sets contained 13C-labeled contaminants to monitor for production of 13C-containing carbon dioxide and cellular material. Microcosm results verified that WBC-2 bioaugmentation can enhance biodegradation, with complete mineralization of chlorobenzene and benzene in bioaugmented and native treatments. Microbial analyses using QuantArrayTM for functional and taxonomic genes indicated potential for co-occurrence of anaerobic and aerobic biodegradation. Compared to the unamended in situ microcosms, the WBC-2 microcosm contained two to five orders of magnitude higher quantities of targeted microbial populations that are associated with degradation of chlorinated and petroleum compounds through both anaerobic and aerobic pathways.

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    Tharmalingam, Tharmala; Goudar, Chetan T

    2015-04-01

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

  5. 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)

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

    CERN Document Server

    Long Tao; Zhang Guo Yi

    2001-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Zhengjun Zhang

    2011-12-01

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

  8. Recommended sublimation pressure and enthalpy of benzene.

    Czech Academy of Sciences Publication Activity Database

    R?ži?ka, K.; Fulem, Michal; ?ervinka, C.

    2014-01-01

    Ro?. 68, Jan (2014), s. 40-47. ISSN 0021-9614 Institutional support: RVO:68378271 Keywords : benzene * vapor pressure * heat capacity * ideal-gas thermodynamic properties * sublimation enthalpy * recommended vapor pressure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.423, year: 2013

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

    Science.gov (United States)

    Züchner, K; Pflaum, U B; Meineke, I

    2014-01-01

    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

  10. 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)

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

    DEFF Research Database (Denmark)

    Elberling, Bo; Kühl, Michael

    2013-01-01

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

  12. Density functional theory studies of Nb–benzene and Nb–borazine sandwich clusters and molecular wires

    International Nuclear Information System (INIS)

    We systematically explored the stabilities, bonding characteristics, electronic and magnetic properties of sandwich-structured Nbn(benzene)n+1 and Nbn(borazine)n+1 clusters (n = 1?4) and molecular wires (n = ?) based on density functional theory. The calculated results show that the lowest energy Nb2(benzene)3 and Nb3(benzene)4 clusters are antiferromagnets (AFMs), while Nb4(benzene)5 is a ferromagnet (FM). An AFM-to-FM transition occurs at n = 4 in the finite Nbn(benzene)n+1 system. For Nbn(borazine)n+1, all the clusters investigated here are ferromagnetically stable. Furthermore, the ground states of infinite [Nb(benzene)]? and [Nb(borazine)]? molecular wires exhibit different electronic structures. The former is a direct-gap ferromagnetic semiconductor, while the latter is a ferromagnetic half-metal. High stabilities and excellent electronic and magnetic properties of [Nb(benzene)]? and [Nb(borazine)]? may be exploited for applications in future electronics and spintronics. (paper)

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2012-10-01

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

  15. Rapid photochemical production of ozone at high concentrations in a rural site during winter

    Science.gov (United States)

    Schnell, Russell C.; Oltmans, Samuel J.; Neely, Ryan R.; Endres, Maggie S.; Molenar, John V.; White, Allen B.

    2009-02-01

    Ozone is an air pollutant that can cause severe respiratory health effects. Photochemical ozone production near the Earth's surface is considered a summertime, urban phenomenon, where hourly average ozone concentrations can exceed 150p.p.b., compared with background values of about 50 p.p.b., and wintertime ozone concentrations in the US are usually in the range of 35-50p.p.b. (refs 1, 2, 3). Here we report rapid, diurnal photochemical production of ozone during air temperatures as low as -17?C, in the rural Upper Green River Basin, Wyoming, in the vicinity of the Jonah-Pinedale Anticline natural gas field. We find that hourly average ozone concentrations rise from 10-30p.p.b. at night to more than 140p.p.b. shortly after solar noon, under the influence of a stagnant, high-pressure system that promotes cold temperatures, low wind speeds and limited cloudiness. Under these conditions, an intense, shallow temperature inversion develops in the lowest 100m of the atmosphere, which traps high concentrations of ozone precursors at night. During daytime, photolytic ozone production then leads to the observed high concentrations. We suggest that similar ozone production during wintertime is probably occurring around the world under comparable industrial and meteorological conditions.

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

    Science.gov (United States)

    Onsekizoglu Bagci, Pelin

    2015-07-01

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

  17. Comparison of charged nanoparticle concentrations near busy roads and overhead high-voltage power lines.

    Science.gov (United States)

    Jayaratne, E R; Ling, X; Morawska, L

    2015-09-01

    Overhead high-voltage power lines are known sources of corona ions. These ions rapidly attach to aerosols to form charged particles in the environment. Although the effect of ions and charged particles on human health is largely unknown, much attention has focused on the increasing exposure as a result of the expanding power network in urban residential areas. However, it is not widely known that a large number of charged particles in urban environments originate from motor vehicle emissions. In this study, for the first time, we compare the concentrations of charged nanoparticles near busy roads and overhead power lines. We show that large concentrations of both positive and negative charged nanoparticles are present near busy roadways and that these concentrations commonly exceed those under high-voltage power lines. We estimate that the concentration of charged nanoparticles found near two freeways carrying around 120 vehicles per minute exceeded the corresponding maximum concentrations under two corona-emitting overhead power lines by as much as a factor of 5. The difference was most pronounced when a significant fraction of traffic consisted of heavy-duty diesel vehicles which typically have high particle and charge emission rates. PMID:25917858

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

    Energy Technology Data Exchange (ETDEWEB)

    Zelener, B. B., E-mail: bobozel@mail.ru; Saakyan, S. A.; Sautenkov, V. A. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation); Manykin, E. A. [National Research Nuclear University “Moscow Engineering Physics Institute,” (Russian Federation); Zelener, B. V.; Fortov, V. E. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

    2014-11-15

    This study is aimed at obtaining high concentration of optically cooled lithium-7 atoms for preparing strongly interacting ultracold plasma and Rydberg matter. A special setup has been constructed, in which two high-power semiconductor lasers are used to cool lithium-7 atoms in a magneto-optical trap. At an optimum detuning of the cooling laser frequency and a magnetic field gradient of 35 G/cm, the concentration of ultracold lithium-7 atoms reaches about 10{sup 11} cm{sup ?3}. Additional independent information about the concentration and number of ultracold lithium-7 atoms on different sublevels of the ground state was obtained by using of an additional probing laser.

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

    Science.gov (United States)

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

    2014-07-01

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

  20. 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)

    Acampora A

    2013-07-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Lowry, N.J.

    1998-10-21

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

  2. Origin of reduced efficiency in high Ga concentration Cu(In,Ga)Se2 solar cell

    Science.gov (United States)

    Wei, S.-H.; Huang, B.; Deng, H.; Contreras, M. A.; Noufi, R.; Chen, S.; Wang, L. W.

    2014-03-01

    CuInSe2 (CIS) is one of the most attractive thin-film materials for solar cells. It is well know that alloying Ga into CIS forming Cu(In,Ga)Se2 (CIGS) alloy is crucial to achieve the high efficiency, but adding too much Ga will lead to a decline of the solar cell efficiency. The exact origin of this puzzling phenomenon is currently still under debate. Using first-principles method, we have systemically studied the structural and electronic properties of CIGS alloys. Our phase diagram calculations suggest that increasing growth temperature may not be a critical factor in enhancing the cell performance of CIGS under equilibrium growth condition. On the other hand, our defect calculations identify that high concentration of antisite defects MCu(M =In, Ga) rather than anion defects are the key deep-trap centers in CIGS. The more the Ga concentration in CIGS, the more harmful the deep-trap is. Self-compensation in CIGS, which forms 2VCu + MCudefect complexes, is found to be beneficial to quench the deep-trap levels induced by MCu in CIGS, especially at low Ga concentration. Unfortunately, the density of isolated MCu is quite high and cannot be largely converted into 2VCu + MCu complexes under thermal equilibrium condition. Thus, nonequilibrium growth conditions or low growth temperature that can suppress the formation of the deep-trap centers MCu may be necessary for improving the efficiency of CIGS solar cells with high Ga concentrations.

  3. The preparation and ethanol fermentation of high-concentration sugars from steam-explosion corn stover.

    Science.gov (United States)

    Xie, Hui; Wang, Fengqin; Yin, Shuangyao; Ren, Tianbao; Song, Andong

    2015-05-01

    In the field of biofuel ethanol, high-concentration- reducing sugars made from cellulosic materials lay the foundation for high-concentration ethanol fermentation. In this study, corn stover was pre-treated in a process combining chemical methods and steam explosion; the cellulosic hydrolyzed sugars obtained by fed-batch saccharification were then used as the carbon source for high-concentration ethanol fermentation. Saccharomyces cerevisiae 1308, Angel yeast, and Issatchenkia orientalis were shake-cultured with Pachysolen tannophilus P-01 for fermentation. Results implied that the ethanol yields from the three types of mixed strains were 4.85 g/100 mL, 4.57 g/100 mL, and 5.02 g/100 mL (separately) at yield rates of 91.6, 89.3, and 92.2 %, respectively. Therefore, it was inferred that shock-fermentation using mixed strains achieved a higher ethanol yield at a greater rate in a shorter fermentation period. This study provided a theoretical basis and technical guidance for the fermentation of industrial high-concentrated cellulosic ethanol. PMID:25877397

  4. 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

  5. Generation of high-titer viral preparations by concentration using successive rounds of ultracentrifugation

    OpenAIRE

    Ichim Christine V; Wells Richard A

    2011-01-01

    Abstract Background Viral vectors provide a method of stably introducing exogenous DNA into cells that are not easily transfectable allowing for the ectopic expression or silencing of genes for therapeutic or experimental purposes. However, some cell types, in particular bone marrow cells, dendritic cells and neurons are difficult to transduce with viral vectors. Successful transduction of such cells requires preparation of highly concentrated viral stocks, which permit a high virus concentra...

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

    Directory of Open Access Journals (Sweden)

    A.K. Gombert

    1997-06-01

    Full Text Available Abstract - A cultivation strategy based on some previous knowledge of the metabolism of Escherichia coli BL21 (DE3 pLysS containing the troponin C gene cloned into plasmid pET was developed and applied through the use of simple fermentation equipment and a feed-forward control strategy in order to achieve a high cell concentration ¾ 92 g l-1 dry cell weight ¾ and a high cell productivity ¾ 3.7 g l-1 h-1.

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

    Scientific Electronic Library Online (English)

    A.K., Gombert; B.V., Kilikian.

    1997-06-01

    Full Text Available Abstract - A cultivation strategy based on some previous knowledge of the metabolism of Escherichia coli BL21 (DE3) pLysS containing the troponin C gene cloned into plasmid pET was developed and applied through the use of simple fermentation equipment and a feed-forward control strategy in order to [...] achieve a high cell concentration ¾ 92 g l-1 dry cell weight ¾ and a high cell productivity ¾ 3.7 g l-1 h-1.

  8. Lack of correlation between environmental or biological indicators of benzene exposure at parts per billion levels and micronuclei induction

    International Nuclear Information System (INIS)

    Despite growing concern for possible carcinogenic effects associated with environmental benzene exposure in the general population, few studies exist at parts per billion (ppb) levels. We investigated the existence of a relationship between airborne/biological measurements of benzene exposure i.e., personal/area sampling and unmodified urinary benzene/trans,trans-muconic acid; t,t-MA) and micronuclei induction cytochalasin B technique) among exposed chemical laboratory workers (n=47) and traffic wardens (n=15). Although urinary t,t-MA (106.9±123.17 ?g/Lurine) correlated (R2=0.37) with urinary benzene (0.66±0.99 ?g/Lurine), neither biological measurement correlated with environmental benzene exposure (14.04±9.71 ?g/m3; 4.39±3.03 ppb), suggesting that, at ppb level (1 ppb=3.2 ?g/m3), airborne benzene constitutes a fraction of the total intake. Traffic wardens and laboratory workers had comparable numbers of micronuclei (4.70±2.63 versus .76±3.11; n.s.), similar to levels recorded in the general population. With univariate/multivariate analysis, no association was found between micronuclei induction and air/urinary benzene exposure variables. Notably, among the personal characteristics examined (including age, gender, smoking, drinking, etc.), high body mass index correlated with micronuclei induction while, among females, use of hormonal medication was associated with less micronuclei. Thus the present stuicronuclei. Thus the present study provides no evidence that ppb levels of environmental benzene exposure appreciably affect micronuclei incidence against the background of other relevant factors). However, this should not be taken as an argument against efforts aiming to reduce environmental benzene pollution

  9. Surface silylation of natural mesoporous/macroporous diatomite for adsorption of benzene.

    Science.gov (United States)

    Yu, Wenbin; Deng, Liangliang; Yuan, Peng; Liu, Dong; Yuan, Weiwei; Liu, Peng; He, Hongping; Li, Zhaohui; Chen, Fanrong

    2015-06-15

    Naturally occurring porous diatomite (Dt) was functionalized with phenyltriethoxysilane (PTES), and the PTES-modified diatomite (PTES-Dt) was characterized using diffuse reflectance Fourier transform infrared spectroscopy, nitrogen adsorption, nuclear magnetic resonance spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. After silylation, a functional group (-C6H5, phenyl) was successfully introduced onto the surface of Dt. PTES-Dt exhibited hydrophobic properties with a water contact angle (WCA) as high as 120°±1°, whereas Dt was superhydrophilic with a WCA of 0°. The benzene adsorption data on both Dt and PTES-Dt fit well with the Langmuir isotherm equation. The Langmuir adsorption capacity of benzene on PTES-Dt is 28.1 mg/g, more than 4-fold greater than that on Dt. Moreover, the adsorption kinetics results show that equilibrium was achieved faster for PTES-Dt than for Dt, over the relative pressure range of 0.118-0.157. The excellent benzene adsorption performance of PTES-Dt is attributed to strong ?-system interactions between the phenyl groups and the benzene molecules as well as to the macroporosity of the PTES-Dt. These results show that the silylated diatomite could be a new and inexpensive adsorbent suitable for use in benzene emission control. PMID:25792477

  10. 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.

  11. Oxygen concentrators for the delivery of supplemental oxygen in remote high-altitude areas.

    Science.gov (United States)

    Litch, J A; Bishop, R A

    2000-01-01

    Oxygen concentrators are a relatively new technology for the delivery of supplemental oxygen. Readily available for domicile use in modern countries, these machines have proved reliable. The application of oxygen concentrators for the supply of medical oxygen in remote high-altitude settings has important cost-saving and supply implications. In our experience at a remote hospital at 3,900 m in the Nepal Himalayas, oxygen concentrators constitute an effective and affordable means to supply medical oxygen. Using an air compressor and 2 zeolite chambers, the machine traps nitrogen from room air compressed to 4 atm, thus concentrating oxygen in the expressed gas. At delivery flow rates of 2 to 5 liters per minute, oxygen concentrations greater than 80% can be maintained. An electric power requirement of less than 400 W can be provided from a variety of sources, including a small gasoline generator, a solar or wind power system with battery store, or a domestic or commercial power source. At our facility, a cost savings of 75% for supplemental oxygen was found in favor of the oxygen concentrator over cylinders (0.17 US cents per liter vs 0.79 US cents per liter). PMID:11055565

  12. Off-pathway aggregation can inhibit fibrillation at high protein concentrations

    DEFF Research Database (Denmark)

    Deva, Taru; Lorenzen, Nikolai

    2013-01-01

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

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

    DEFF Research Database (Denmark)

    Bruunsgaard, H.; Andersen-Ranberg, K.

    1999-01-01

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

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

    Science.gov (United States)

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

    2011-04-01

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

  15. Microscopic protein diffusion at high concentration by neutron spin-echo spectroscopy

    Science.gov (United States)

    Le Coeur, C.; Longeville, S.

    2008-04-01

    Molecular transport and reactions in biological cells are strongly affected by the presence of macromolecules at high concentration. We studied the intermolecular structure and diffusion of oxygen carriers myoglobin and hemoglobin in concentrated solutions using neutron diffraction and spin-echo spectroscopy. The self-diffusion coefficient measured by NSE spectroscopy is compatible with theoretical prediction for long-time self-diffusion coefficient for colloids. We measured I( q, t) for q ? 1 Å -1 trying to observe the short-time diffusion coefficient. A signal which can be attributed to the protein is observed but which origin can neither be attributed to translational nor rotational diffusion.

  16. Microscopic protein diffusion at high concentration by neutron spin-echo spectroscopy

    International Nuclear Information System (INIS)

    Molecular transport and reactions in biological cells are strongly affected by the presence of macromolecules at high concentration. We studied the intermolecular structure and diffusion of oxygen carriers myoglobin and hemoglobin in concentrated solutions using neutron diffraction and spin-echo spectroscopy. The self-diffusion coefficient measured by NSE spectroscopy is compatible with theoretical prediction for long-time self-diffusion coefficient for colloids. We measured I(q, t) for q ? 1 A-1 trying to observe the short-time diffusion coefficient. A signal which can be attributed to the protein is observed but which origin can neither be attributed to translational nor rotational diffusion

  17. 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.

  18. Production of highly concentrated, heat stable hepatitis B surface antigen in maize

    OpenAIRE

    Hayden, Celine A.; Egelkrout, Erin M.; Moscoso, Alessa M.; Enrique, Cristina; Keener, Todd K.; Jimenez-flores, Rafael; Wong, Jeffrey C.; Howard, John A.

    2012-01-01

    Plant-based oral vaccines are a promising emergent technology that could help alleviate disease burden worldwide by providing a low-cost, heat stable, oral alternative to parenterally administered commercial vaccines. Here we describe high-level accumulation of the hepatitis B surface antigen (HBsAg) at a mean concentration of 0.51%TSP in maize T1 seeds using an improved version of the globulin1 promoter. This concentration is more than four-fold higher than any previously reported lines. HBs...

  19. The potential of np GaAs solar cells for high efficiency concentrator applications

    Science.gov (United States)

    Flat, A.; Milnes, A. G.

    1979-01-01

    This communication considers the design of the front grid contact of np GaAs solar cells for high efficiency concentrator applications. This design involves shadowing, contact resistance, and active layer sheet resistance losses, and at high concentrations, the power loss due to voltage drop on the resistance of the grid fingers should be considered. Analysis of the performance can be calculated as a function of junction depth and surface recombination velocity. The junction depth can be optimized by considering its effect on the collection efficiency of the dark current-voltage characteristics or the open circuit voltage, and on the series resistance loss or the fill factor for material parameters. The choice of the material parameters, calculation of the short circuit current, the selection of the n layer thickness, and the cell maximum power and efficiency are discussed. It is concluded that optimized multi-grid structures should allow the use of 10 by 10 sq cm cells with good efficiencies at high concentration ratios, and efficiencies of 22 to 25% should be obtainable from large area cells at concentrations of 40 AM1.

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

    Science.gov (United States)

    Feuermann, Daniel; Gordon, Jeffrey M.

    1999-10-01

    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.

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

    Science.gov (United States)

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

    2014-03-01

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

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-11-29

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

  4. Influence of a High-Pressure Comminution Technology on Concentrate Yields in Copper Ore Flotation Processes

    Directory of Open Access Journals (Sweden)

    Saramak D.

    2014-10-01

    Full Text Available The article concerns the issues of flotation process effectiveness in relationship to the operating conditions of a high-pressure comminution process course. Experimental programme covering a flotation laboratory batch tests was a verification technique of a high-pressure crushing operations course. The most favorable values of flotation concentrate weight recoveries were obtained for the pressing force 6 kN and 4% of the feed moisture. It was also determined the model of the concentrate weight recovery as a function of pressing force in the press and feed moisture content. This model was the basis for the optimization of effects of copper ore flotation processes preceded in high-pressure crushing operation in roller presses.

  5. Organic chemistry. A rhodium catalyst for single-step styrene production from benzene and ethylene.

    Science.gov (United States)

    Vaughan, Benjamin A; Webster-Gardiner, Michael S; Cundari, Thomas R; Gunnoe, T Brent

    2015-04-24

    Rising global demand for fossil resources has prompted a renewed interest in catalyst technologies that increase the efficiency of conversion of hydrocarbons from petroleum and natural gas to higher-value materials. Styrene is currently produced from benzene and ethylene through the intermediacy of ethylbenzene, which must be dehydrogenated in a separate step. The direct oxidative conversion of benzene and ethylene to styrene could provide a more efficient route, but achieving high selectivity and yield for this reaction has been challenging. Here, we report that the Rh catalyst ((Fl)DAB)Rh(TFA)(?(2)-C2H4) [(Fl)DAB is N,N'-bis(pentafluorophenyl)-2,3-dimethyl-1,4-diaza-1,3-butadiene; TFA is trifluoroacetate] converts benzene, ethylene, and Cu(II) acetate to styrene, Cu(I) acetate, and acetic acid with 100% selectivity and yields ?95%. Turnover numbers >800 have been demonstrated, with catalyst stability up to 96 hours. PMID:25908817

  6. Circulating adiponectin concentration and body composition are altered in response to high-intensity interval training.

    Science.gov (United States)

    Shing, Cecilia M; Webb, Jessica J; Driller, Matthew W; Williams, Andrew D; Fell, James W

    2013-08-01

    Adiponectin influences metabolic adaptations that would prove beneficial to endurance athletes, and yet to date there is little known about the response of adiponectin concentrations to exercise, and, in particular, the response of this hormone to training in an athlete population. This study aimed to determine the response of plasma adiponectin concentrations to acute exercise after 2 different training programs and to determine the influence of the training on body composition. Seven state-level representative rowers (age: 19 ± 1.2 years [mean ± SD], height: 1.77 ± 0.10 m, body mass: 74.0 ± 10.7 kg, VO2peak 62.1 ± 7.0 ml·kg·min) participated in the double-blind, randomized crossover investigation. Rowers performed an incremental graded exercise test before and after completing 4 weeks of high-intensity interval ergometer training and 4 weeks of traditional ergometer rowing training. Rowers' body composition was assessed at baseline and after each training program. Significant increases in plasma adiponectin concentration occurred in response to maximal exercise after completion of the high-intensity interval training (p = 0.016) but not after traditional ergometer rowing training (p = 0.69). The high-intensity interval training also resulted in significant increases in mean 4-minute power output (p = 0.002) and VO2peak (p = 0.05), and a decrease in body fat percentage (p = 0.022). Mean 4-minute power output, VO2peak, and body fat percentage were not significantly different after 4 weeks of traditional ergometer rowing training (p > 0.05). Four weeks of high-intensity interval training is associated with an increase in adiponectin concentration in response to maximal exercise and a reduction in body fat percentage. The potential for changes in adiponectin concentration to reflect positive training adaptations and athlete performance level should be further explored. PMID:23222083

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

    OpenAIRE

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

    2007-01-01

    Secondary organic aerosol (SOA) formation from the photooxidation of m-xylene, toluene, and benzene is investigated in the Caltech environmental chambers. Experiments are performed under two limiting NOx conditions; under high-NOx conditions the peroxy radicals (RO2) react only with NO, while under low-NOx conditions they react only with HO2. For all three aromatics studied (m-xylene, toluene, and benzene), the SOA yields (defined as the ratio of the mass of organic aerosol formed to the mass...

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

    OpenAIRE

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

    2007-01-01

    Secondary organic aerosol (SOA) formation from the photooxidation of m-xylene, toluene, and benzene is investigated in the Caltech environmental chambers. Experiments are performed under two limiting NOx conditions; under high-NOx conditions the peroxy radicals (RO2) react only with NO, while under low-NOx conditions they react only with HO2. For all three aromatics studied (m-xylene, toluene, and benzene), the SOA yields (defined as the ratio of the mass of organic aerosol formed to the mass...

  9. Thermodynamically consistent description of the hydrodynamics of free surfaces covered by insoluble surfactants of high concentration

    CERN Document Server

    Thiele, Uwe; Plapp, Mathis

    2012-01-01

    In this paper we propose several models that describe the dynamics of liquid films which are covered by a high concentration layer of insoluble surfactant. First, we briefly review the 'classical' hydrodynamic form of the coupled evolution equations for the film height and surfactant concentration that are well established for small concentrations. Then we re-formulate the basic model as a gradient dynamics based on an underlying free energy functional that accounts for wettability and capillarity. Based on this re-formulation in the framework of nonequilibrium thermodynamics, we propose extensions of the basic hydrodynamic model that account for (i) nonlinear equations of state, (ii) surfactant-dependent wettability, (iii) surfactant phase transitions, and (iv) substrate-mediated condensation. In passing, we discuss important differences to most of the models found in the literature.

  10. Chemical durability of high burnup LWR-spent fuel in concentrated salt solutions

    International Nuclear Information System (INIS)

    High-burnup (>50 MWd/kgU) spent fuel samples of various sizes were exposed to NaCl solutions under static, anaerobic and reducing conditions. The accumulated corrosion time was about 200 days. Gas phase and leach solutions were analyzed. By dissolving mm sized fragments in large volumes of solution, saturation effects were avoided and upper limits for intrinsic dissolution rates of about 5-20 mg/(m2d) were measured. Surface area normalized reaction rates were significantly lower when using fine grained fuel powder (estimated sample surface area to solution volume ratio S/V ca. 3000 m-1), indicating saturation effects. The maximum concentrations of Pu and Am in the tests are close to reported solubility limited concentrations in pure 5m NaCl solutions in the absence of radiolysis effects. The presence of iron effectively reduces the solution concentration of all measured radionuclides (except Cs)

  11. Plasma PCSK9 concentrations during an oral fat load and after short term high-fat, high-fat high-protein and high-fructose diets

    Directory of Open Access Journals (Sweden)

    Cariou Bertrand

    2013-01-01

    Full Text Available Abstract Background PCSK9 (Proprotein Convertase Subtilisin Kexin type 9 is a circulating protein that promotes hypercholesterolemia by decreasing hepatic LDL receptor protein. Under non interventional conditions, its expression is driven by sterol response element binding protein 2 (SREBP2 and follows a diurnal rhythm synchronous with cholesterol synthesis. Plasma PCSK9 is associated to LDL-C and to a lesser extent plasma triglycerides and insulin resistance. We aimed to verify the effect on plasma PCSK9 concentrations of dietary interventions that affect these parameters. Methods We performed nutritional interventions in young healthy male volunteers and offspring of type 2 diabetic (OffT2D patients that are more prone to develop insulin resistance, including: i acute post-prandial hyperlipidemic challenge (n=10, ii 4 days of high-fat (HF or high-fat/high-protein (HFHP (n=10, iii 7 (HFruc1, n=16 or 6 (HFruc2, n=9 days of hypercaloric high-fructose diets. An acute oral fat load was also performed in two patients bearing the R104C-V114A loss-of-function (LOF PCSK9 mutation. Plasma PCSK9 concentrations were measured by ELISA. For the HFruc1 study, intrahepatocellular (IHCL and intramyocellular lipids were measured by 1H magnetic resonance spectroscopy. Hepatic and whole-body insulin sensitivity was assessed with a two-step hyperinsulinemic-euglycemic clamp (0.3 and 1.0 mU.kg-1.min-1. Findings HF and HFHP short-term diets, as well as an acute hyperlipidemic oral load, did not significantly change PCSK9 concentrations. In addition, post-prandial plasma triglyceride excursion was not altered in two carriers of PCSK9 LOF mutation compared with non carriers. In contrast, hypercaloric 7-day HFruc1 diet increased plasma PCSK9 concentrations by 28% (p=0.05 in healthy volunteers and by 34% (p=0.001 in OffT2D patients. In another independent study, 6-day HFruc2 diet increased plasma PCSK9 levels by 93% (p Conclusions Plasma PCSK9 concentrations vary minimally in response to a short term high-fat diet and they are not accompanied with changes in cholesterolemia upon high-fructose diet. Short-term high-fructose intake increased plasma PCSK9 levels, independent on cholesterol synthesis, suggesting a regulation independent of SREBP-2. Upon this diet, PCSK9 is associated with insulin resistance, hepatic steatosis and plasma triglycerides.

  12. Exposure to methyl tert-butyl ether, benzene, and total hydrocarbons at the Singapore-Malaysia causeway immigration checkpoint

    Energy Technology Data Exchange (ETDEWEB)

    Tan, C.; Ong, H.Y.; Kok, P.W. [and others

    1996-12-31

    The primary aim of this study was to determine the extent and levels of exposure to volatile organic compounds (VOCs) from automobile emissions in a group of immigration officers at a busy cross-border checkpoint. A majority (80%) of the workers monitored were exposed to benzene at levels between 0.01 and 0.5 ppm, with only 1.2% exceeding the current Occupational Safety and Health Administration occupational exposure limit of 1 ppm. The geometric mean (GM) concentrations of 8-hr time-weighted average exposure were 0.03 ppm, 0.9 ppm, and 2.46 ppm for methyl-tert-butyl ether (MTBE), benzene, and total hydrocarbons (THC), respectively. The highest time-weighted average concentrations measured were 1.05 ppm for MTBE, 2.01 ppm for benzene, and 34 ppm for THC. It was found that motorbikes emitted a more significant amount of pollutants compared with motor cars. On average, officers at the motorcycle booths were exposed to four to five times higher levels of VOCs (GMs of 0.07 ppm, 0.23 ppm, and 4.7 ppm for MTBE, benzene, and THC) than their counterparts at the motor car booths (GMs of 0.01 ppm, 0.05 ppm, and 1.5 ppm). The airborne concentrations of all three pollutants correlated with the flow of vehicle traffic. Close correlations were also noted for the concentrations in ambient air for the three pollutants measured. Benzene and MTBE had a correlation coefficient of 0.97. The overall findings showed that the concentrations of various VOCs were closely related to the traffic density, suggesting that they were from a common source, such as exhaust emissions from the vehicles. The results also indicated that although benzene, MTBE, and THC are known to be volatile, a significant amount could still be detected in the ambient environment, thus contributing to our exposure to these compounds. 4 refs., 6 figs.

  13. Generation of high-titer viral preparations by concentration using successive rounds of ultracentrifugation

    Directory of Open Access Journals (Sweden)

    Ichim Christine V

    2011-08-01

    Full Text Available Abstract Background Viral vectors provide a method of stably introducing exogenous DNA into cells that are not easily transfectable allowing for the ectopic expression or silencing of genes for therapeutic or experimental purposes. However, some cell types, in particular bone marrow cells, dendritic cells and neurons are difficult to transduce with viral vectors. Successful transduction of such cells requires preparation of highly concentrated viral stocks, which permit a high virus concentration and multiplicity of infection (MOI during transduction. Pseudotyping with the vesicular stomatitis virus G (VSV-G envelope protein is common practice for both lentiviral and retroviral vectors. The VSV-G glycoprotein adds physical stability to retroviral particles, allowing concentration of virus by high-speed ultracentrifugation. Here we describe a method report for concentration of virus from large volumes of culture supernatant by means of successive rounds of ultracentrifugation into the same ultracentrifuge tube. Method Stable retrovirus producer cell lines were generated and large volumes of virus-containing supernatant were produced. We then tested the transduction ability of virus following varying rounds of concentration by ultra-centrifugation. In a second series of experiments lentivirus-containing supernatant was produced by transient transfection of 297T/17 cells and again we tested the transduction ability of virus following multiple rounds of ultra-centrifugation. Results We report being able to centrifuge VSV-G coated retrovirus for as many as four rounds of ultracentrifugation while observing an additive increase in viral titer. Even after four rounds of ultracentrifugation we did not reach a plateau in viral titer relative to viral supernatant concentrated to indicate that we had reached the maximum tolerated centrifugation time, implying that it may be possible to centrifuge VSV-G coated retrovirus even further should it be necessary to achieve yet higher titers for specific applications. We further report that VSV-G coated lentiviral particles may also be concentrated by successive rounds of ultracentrifugation (in this case four rounds with minimal loss of transduction efficiency. Conclusion This method of concentrating virus has allowed us to generate virus of sufficient titers to transduce bone marrow cells with both retrovirus and lentivirus, including virus carrying shRNA constructs.

  14. Radiolysis of Aqueous Benzene Solutions at higher temperatures

    International Nuclear Information System (INIS)

    Aqueous solutions of benzene have been irradiated with Co ?-rays with doses of up to 2.3 Mrad in the temperature region 100 - 200 C. At 100 C a linear relationship between the phenol concentration and the absorbed dose was obtained, but at 150 C and at higher temperatures the rate of the phenol formation increased significantly after an initial constant period. With higher doses the rate decreased again, falling almost to zero at 200 C after a dose of 2.2 Mrad. The G value of phenol in the initial linear period increased from 2.8 at 100 C to 8.0 at 200 C. The reaction mechanism is discussed and reactions constituting a chain reaction are suggested. The result of the addition of iron ions and of a few inorganic oxides to the system is presented and briefly discussed

  15. Factors affecting biotic mercury concentrations and biomagnification through lake food webs in the Canadian high Arctic.

    Science.gov (United States)

    Lescord, Gretchen L; Kidd, Karen A; Kirk, Jane L; O'Driscoll, Nelson J; Wang, Xiaowa; Muir, Derek C G

    2015-03-15

    In temperate regions of Canada, mercury (Hg) concentrations in biota and the magnitude of Hg biomagnification through food webs vary between neighboring lakes and are related to water chemistry variables and physical lake features. However, few studies have examined factors affecting the variable Hg concentrations in landlocked Arctic char (Salvelinus alpinus) or the biomagnification of Hg through their food webs. We estimated the food web structure of six high Arctic lakes near Resolute Bay, Nunavut, Canada, using stable carbon (?(13)C) and nitrogen (?(15)N) isotopes and measured Hg (total Hg (THg) in char, the only fish species, and methylmercury (MeHg) in chironomids and zooplankton) concentrations in biota collected in 2010 and 2011. Across lakes, ?(13)C showed that benthic carbon (chironomids) was the dominant food source for char. Regression models of log Hg versus ?(15)N (of char and benthic invertebrates) showed positive and significant slopes, indicting Hg biomagnification in all lakes, and higher slopes in some lakes than others. However, no principal components (PC) generated using all water chemistry data and physical characteristics of the lakes predicted the different slopes. The PC dominated by aqueous ions was a negative predictor of MeHg concentrations in chironomids, suggesting that water chemistry affects Hg bioavailability and MeHg concentrations in these lower-trophic-level organisms. Furthermore, regression intercepts were predicted by the PCs dominated by catchment area, aqueous ions, and MeHg. Weaker relationships were also found between THg in small char or MeHg in pelagic invertebrates and the PCs dominated by catchment area, and aqueous nitrate and MeHg. Results from these high Arctic lakes suggest that Hg biomagnification differs between systems and that their physical and chemical characteristics affect Hg concentrations in lower-trophic-level biota. PMID:24909711

  16. Benzene-mediated protein kinase C activation.

    OpenAIRE

    Da Silva, C.; Fan, X. T.; Castagna, M.

    1989-01-01

    Extracellular ligands transfer information into the cell through several pathways that operate in an integrated fashion. Protein kinase C, and enzyme that plays a pivotal role in signal transduction, is the molecular target for tumor promoters from the series of phorbol esters. A number of structurally unrelated tumor promoters also enhance protein kinase C, interacting or not interacting with the phorbol ester binding site. Evidence is provided that benzene potently activate protein kinase C...

  17. Differences in the metabolism and disposition of inhaled [3H]benzene by F344/N rats and B6C3F1 mice

    International Nuclear Information System (INIS)

    Benzene is a potent hematotoxin and has been shown to cause leukemia in man. Chronic toxicity studies indicate that B6C3F1 mice are more susceptible than F334/N rats to benzene toxicity. The purpose of the studies presented in this paper was to determine if there were metabolic differences between F344/N rats and B6C3F1 mice which might be responsible for this increased susceptibility. Metabolites of benzene in blood, liver, lung, and bone marrow were measured during and following a 6-hr 50 ppm exposure to benzene vapor. Hydroquinone glucuronide, hydroquinone, and muconic acid, which reflect pathways leading to potential toxic metabolites of benzene, were present in much greater concentrations in the mouse than in rat tissues. Phenylsulfate, a detoxified metabolite, and an unknown water-soluble metabolite were present in approximately equal concentrations in these two species. These results indicate that the proportion of benzene metabolized via pathways leading to the formation of potentially toxic metabolites as opposed to detoxification pathways was much higher in B6C3F1 mice than in F344 rats, which may explain the higher susceptibility of mice to benzene-induced hematotoxicity and carcinogenicity

  18. An approach to the subslab depressurization remedial action in a high 222Rn concentration dwelling

    International Nuclear Information System (INIS)

    Galicia (NW Spain) is a radon-prone area in the Iberian Peninsula. Measurements were carried out at a rural dwelling, with an annual average of radon concentration over 4000 Bq m-3 and a maximum of 9000 Bq m-3, found during a radon screening campaign held in the Autonomous Community of Galicia. We performed a detailed study to identify the main contamination source and the behaviour of the radon concentration, in which a linear dependence with temperature was verified, once corrected for relative humidity. We used different passive methods (charcoal canisters and two types of etched track detectors) as well as a radon concentration monitor that provided continuous measurement. Subsequent to this characterization, and in order to reduce the high radon concentration, a remedial action was developed using different passive and forced ventilation methods. A modified subslab depressurization technique was found to be the most effective remedy, providing a radon concentration reduction of around 96%. This method also has the advantages of being inexpensive and reliable over time.

  19. High variability of dissolved iron concentrations in the vicinity of Kerguelen Island (Southern Ocean

    Directory of Open Access Journals (Sweden)

    F. Quéroué

    2015-01-01

    Full Text Available Dissolved Fe (dFe concentrations were measured in the upper 1300 m of the water column in the vicinity of Kerguelen Island as part of the second Kerguelen Ocean Plateau compared Study (KEOPS2. Concentrations ranged from 0.06 nmol L?1 in offshore, Southern Ocean waters, to 3.82 nmol L?1 within Hillsborough Bay, on the north-eastern coast of Kerguelen Island. Direct island runoff, glacial melting and resuspended sediments were identified as important inputs of dFe that could potentially fertilize the northern part of the plateau. A significant deep dFe enrichment was observed over the plateau with dFe concentrations increasing up to 1.30 nmol L?1 close to the seafloor, probably due to sediment resuspension and pore water release. Biological uptake was identified as a likely explanation for the decrease in dFe concentrations between two visits (28 days apart at a station above the plateau. Our results allowed studying other processes and sources, such as atmospheric inputs, lateral advection of enriched seawater, remineralization processes and the influence of the Polar Front (PF as a vector for Fe transport. Overall, heterogeneous sources of Fe over and off the Kerguelen Plateau, in addition to strong variability in Fe supply by vertical or horizontal transport, may explain the high variability in dFe concentrations observed during this study.

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

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, Kelly Cristina Santana de

    2006-07-01

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

  1. Continuous Ethanol Production with a Membrane Bioreactor at High Acetic Acid Concentrations

    Directory of Open Access Journals (Sweden)

    Päivi Ylitervo

    2014-07-01

    Full Text Available The release of inhibitory concentrations of acetic acid from lignocellulosic raw materials during hydrolysis is one of the main concerns for 2nd generation ethanol production. The undissociated form of acetic acid can enter the cell by diffusion through the plasma membrane and trigger several toxic effects, such as uncoupling and lowered intracellular pH. The effect of acetic acid on the ethanol production was investigated in continuous cultivations by adding medium containing 2.5 to 20.0 g·L?1 acetic acid at pH 5.0, at a dilution rate of 0.5 h?1. The cultivations were performed at both high (~25 g·L?1 and very high (100–200 g·L?1 yeast concentration by retaining the yeast cells inside the reactor by a cross-flow membrane in a membrane bioreactor. The yeast was able to steadily produce ethanol from 25 g·L?1 sucrose, at volumetric rates of 5–6 g·L?1·h?1 at acetic acid concentrations up to 15.0 g·L?1. However, the yeast continued to produce ethanol also at a concentration of 20 g·L?1 acetic acid but at a declining rate. The study thereby demonstrates the great potential of the membrane bioreactor for improving the robustness of the ethanol production based on lignocellulosic raw materials.

  2. High Pb concentration stress on Typha latifolia growth and Pb removal in microcosm wetlands.

    Science.gov (United States)

    Han, Jianqiu; Chen, Fengzhen; Zhou, Yumei; Wang, Chaohua

    2015-01-01

    When constructed wetlands are used to treat high-Pb wastewater, Pb may become a stress to wetland plants, which subsequently reduces treatment performance and the other ecosystem services. To facilitate the design and operation of constructed wetlands for treatment of Pb-rich wastewater, we investigated the irreversible inhibitory level of Pb for Typha latifolia through experiments in microcosm wetlands. Seven horizontal subsurface flow constructed wetlands were built with rectangular plastic tanks and packed with marble chips and sand. All wetlands were transplanted with nine stems of Typha latifolia each. The wetlands were batch operated in a greenhouse with artificial wastewater (10 L each) for 12 days. Influent to the seven wetlands had different concentrations of Pb: 0 mg/L, 10 mg/L, 25 mg/L, 50 mg/L, 100 mg/L, 200 mg/L, and 500 mg/L, respectively. The results suggested that leaf chlorophyll relative content, relative growth rate, photosynthetic characteristics, activities of superoxide dismutase, peroxidase, and content of malondialdehyde were not affected when initial Pb concentration was at 100 mg/L and below. But when initial Pb concentration was above 100 mg/L, all of them were seriously affected. We conclude that high Pb concentrations wastewater could inhibit the growth of Typha latifolia and decrease the removal rate of wetlands. PMID:26038940

  3. A modified coaxial electrospinning for preparing fibers from a high concentration polymer solution

    Directory of Open Access Journals (Sweden)

    2011-08-01

    Full Text Available A new process technology modified from conventional coaxial electrospinning process has been developed to prepare polymer fibers from a high concentration solution. This process involves a pure solvent concentrically surrounding polymer fluid in the spinneret. The concentric spinneret was constructed simply by inserting a metal needle through a high elastic silica gel tube. Two syringe pumps were used to drive the core polymer solution and the sheath solvent. Using polyvinylpyrrolidone (PVP as the polymer model, which normally has an electrospinnable concentration of 10% w/v in ethanol, it was possible to electrospin 35% w/v of PVP in the same solvent, when pure N, N-dimethylacetamide (DMAc was used as sheath fluid. The resultant fibers have a smooth surface morphology and good structural uniformity. The diameter of the fibers was 2.0±0.25 µm when the DMAc-to-polymer-solution flow rate ratio was set as 0.1. The process technology reported here opens a new window to tune the polymer fibers obtained by the electrospinning, and is useful for improving productivity of the electrospinning process.

  4. Air ion mobility spectra and concentrations upwind and downwind of overhead AC high voltage power lines

    Science.gov (United States)

    Wright, Matthew D.; Buckley, Alison J.; Matthews, James C.; Shallcross, Dudley E.; Henshaw, Denis L.

    2014-10-01

    Corona ions produced by high-voltage power lines (HVPLs) can alter the nearby electrical environment, potentially increasing aerosol charge levels downwind. However, there is a lack of knowledge concerning the concentration and mobility of ions from AC HVPLs and their dispersion away from the line. We present ion concentration and mobility measurements made near AC HVPLs in South-West England. Examples of typical mobility spectra are shown highlighting features commonly observed. Corona was observed during 33 of 46 measurements, at 9 of 11 sites, with positive or ‘bipolar' (both polarities) ion production commonly seen. Ion production usually increases atmospheric concentrations by only a modest amount, but extreme cases can enhance concentration by an order of magnitude or more. A polarity imbalance is required to increase aerosol charge via ion attachment; this was observed on 15 of 24 days when positive corona was observed, but was not seen for negative ions. Ion mobility was higher downwind compared with upwind for both ion polarities, but the increase was not statistically significant. Future work should focus on identifying and characterising ‘heavy-producing' HVPLs, and obtaining results in conditions which may favour negative ion production e.g. high humidity, inclement weather or during nighttime.

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

    International Nuclear Information System (INIS)

    Full text: Radium in natural water springs presents two main problems in radiological protection. The first problem is the direct 226Ra ingestion during the water consumption. The second problem is concerning the fact that the elevated radium concentration in water springs is the source of possible soil contamination by 226Ra and high radon concentration in the atmosphere of the dwellings situated over the contaminated place. Due to high radiotoxicity 226Ra is characterized by low action level (0.5 Bq/l for drinking water) and a high sensitivity technique is required to measure such low concentrations. The developed method of 226Ra concentration measurements is based on emanation technique: the specific activity of 226Ra is determined by radon volume activity measurement in closed system during the water sample bubbling. The main measuring steps are: Degassing, sealing and storage of the water sample during at least 2 weeks; Absorption of background 222Rn in the inner volume of measuring system consisting of radon monitor AlphaGUARD, set of glass vials AlphaKIT and air pump AlphaPUMP; Transfer of water sample in the system and beginning of air bubbling through the sample. Measurement of 222Rn concentration in closed system (at least 10 values of radon concentration) The minimum detected specific activity of 226Ra in such technique is 0.03 Bq/l without any need for preliminary radiuq/l without any need for preliminary radium concentration. After 2 week interval the water sample can be repeatedly measured. The 226Ra in water was measured in 4 regions with high levels of radon in dwellings: Ural (Russia), Niska Banja (Serbia), Caucasus (Russia) and Issyk-Kul (Kyrgyzstan). It was founded that high radon concentration in water (400-600 Bq/l) is not always lead to radium presence in the sample. In practically all of measured samples the radium specific activity was either below action level or a little above it. A close correlation between 226Ra in water and radon in dwellings was found only in Niska Banja and Caucasus. For these places the formation of travertine during the interaction of radium in water and limestone is typical. It should be noted that low 226Ra specific activity in water (approx. 0.15-0.4 Bq/l) can lead to high radium specific activity in travertine (up to 1000-1500 Bq/kg) and extremely high indoor radon concentration. The maximum 226Ra specific activity was measured in spring waters 'Slavyanovskaya' and 'Smirnovskaya' sampled in Zheleznovodsk (Caucasus) - 4.1 and 2.1 Bq/l. It should be noted that these waters are traditionally used as a mineral waters prescribed for treatment of gastrointestinal disorders during more then 150 years

  6. Soil adsorption alters bioavailability of benzene in dermally exposed male rats

    International Nuclear Information System (INIS)

    The potential for exposure to chemically contaminated soil is a concern for chemical industry and waste disposal site workers as well as for individuals living near the contamination site. Current assessment of potential health risks from these types of exposures relies almost exclusively on extrapolations from data derived with pure chemicals. Complex interactions with soil, however, may alter greatly the way in which a chemical subsequently interacts with the body. This study was conducted to determine if soil adsorption alters the way in which benzene, a common chemical contaminant, enters and is handled by the body following dermal exposure. A shallow glass cap covering approximately a 13-cm2 area was fixed tightly to the shaved skin of each adult male rat tested; 300 microL of 14C-benzene alone or with 1 g of clay or sandy soil was introduced under the cap through an opening which was sealed immediately. Pure benzene produced the highest peak plasma concentration of radioactivity, followed closely by sandy soil-adsorbed benzene, with the lowest value exhibited by clay soil-adsorbed benzene. The plasma elimination half-lives were as follows:sandy (24.5 hr), pure (23.0 hr), and clay (19.4 hr). The tissue concentrations of radioactivity 48 hr post administration were highest in treated skin (covered by the glass cap), followed by the kidney and liver in both soil-treated groups, and were highest in the kidney followed by the liver and treated skin in the pure pure liver and treated skin in the pure pure

  7. A high-performance photovoltaic concentrator array - The mini-dome Fresnel lens concentrator with 30 percent efficient GaAs/GaSb tandem cells

    Science.gov (United States)

    Piszczor, M. F.; Brinker, D. J.; Flood, D. J.; Avery, J. E.; Fraas, L. M.; Fairbanks, E. S.; Yerkes, J. W.; O'Neill, M. J.

    1991-01-01

    A high-efficiency, lightweight space photovoltaic concentrator array is described. Previous work on the minidome Fresnel lens concentrator concept is being integrated with Boeing's 30 percent efficient tandem GaAs/GaSb concentrator cells into a high-performance photovoltaic array. Calculations indicate that, in the near term, such an array can achieve 300 W/sq m at a specific power of 100 W/kg. Emphasis of the program has now shifted to integrating the concentrator lens, tandem cell, and supporting panel structure into a space-qualifiable array. A description is presented of the current status of component and prototype panel testing and the development of a flight panel for the Photovoltaic Array Space Power Plus Diagnostics (PASP PLUS) flight experiment.

  8. Simplification of Sun Tracking Mode to Gain High Concentration Solar Energy

    Directory of Open Access Journals (Sweden)

    Omar Aliman

    2007-01-01

    Full Text Available Power conversion from solar thermal energy to electrical energy is still very cost-intensive. Serious effort has to be given in the development of the concentrator or heliostat structure expenditure which contributing the most expensive component in a central receiver solar power plant. With current development to find alternatives and lower down the capital, a new mode of sun tracking has been developed and feasibility tested. As it applies a single stage collector replacing conventional double stages structure, the new technique has significantly benefits use in high temperature and high concentration solar energy applications. Meanwhile, the stationary or fixed target (receiver offers more convenient working environment for various applications. Large and heavy solar powered Stirling Engine could be placed at the stationary location. On the other advantage offers by the new technique, the optical alignment was reasonably easier and less time consuming.

  9. First report worldwide of huge retroperitoneal pseudocyst with high fluid concentration of CA 125

    International Nuclear Information System (INIS)

    Background: Primary non-traumatic retroperitoneal pseudocysts are very rare; until now those containing high fluid concentration of CA 125 have not been described. Case Report: A 27-year-old male was admitted to our Department with a symptomatic, huge retroperitoneal cystic lesion of unknown origin. It was totally excised, with surrounding organs left intact. Plasma levels of neoplasm markers were normal; history of trauma, pancreatic and urogenital diseases was denied. The cyst contained transparent fluid with very high concentration of Cancer Antigen 125 (CA 125 > 600 U/ml); cyst fluid culture was negative. Histopathological examination showed absence of an epithelial lining; the wall was composed of dense connective tissue. Thus, diagnosis of retroperitoneal pseudocyst was established. Conclusions: Surgeons should be made aware of the possible occurrence of benign retroperitoneal cystic masses of unknown origin which may have many atypical characteristics, including elevated fluid malignancy markers. (authors)

  10. Strategies of Nitrosomonas europaea 19718 to counter low dissolved oxygen and high nitrite concentrations

    Directory of Open Access Journals (Sweden)

    Chandran Kartik

    2010-03-01

    Full Text Available Abstract Background Nitrosomonas europaea is a widely studied chemolithoautotrophic ammonia oxidizing bacterium. While significant work exists on the ammonia oxidation pathway of N. europaea, its responses to factors such as dissolved oxygen limitation or sufficiency or exposure to high nitrite concentrations, particularly at the functional gene transcription level are relatively sparse. The principal goal of this study was to investigate responses at the whole-cell activity and gene transcript levels in N. europaea 19718 batch cultures, which were cultivated at different dissolved oxygen and nitrite concentrations. Transcription of genes coding for principal metabolic pathways including ammonia oxidation (amoA, hydroxylamine oxidation (hao, nitrite reduction (nirK and nitric oxide reduction (norB were quantitatively measured during batch growth, at a range of DO concentrations (0.5, 1.5 and 3.0 mg O2/L. Measurements were also conducted during growth at 1.5 mg O2/L in the presence of 280 mg-N/L of externally added nitrite. Results Several wide ranging responses to DO limitation and nitrite toxicity were observed in N. europaea batch cultures. In contrast to our initial hypothesis, exponential phase mRNA concentrations of both amoA and hao increased with decreasing DO concentrations, suggesting a mechanism to metabolize ammonia and hydroxylamine more effectively under DO limitation. Batch growth in the presence of 280 mg nitrite-N/L resulted in elevated exponential phase nirK and norB mRNA concentrations, potentially to promote utilization of nitrite as an electron acceptor and to detoxify nitrite. This response was in keeping with our initial hypothesis and congruent with similar responses in heterotrophic denitrifying bacteria. Stationary phase responses were distinct from exponential phase responses in most cases, suggesting a strong impact of ammonia availability and metabolism on responses to DO limitation and nitrite toxicity. In general, whole-cell responses to DO limitation or nitrite toxicity, such as sOUR or nitrite reduction to nitric oxide (NO did not parallel the corresponding mRNA (nirK profiles, suggesting differences between the gene transcription and enzyme translation or activity levels. Conclusions The results of this study show that N. europaea possesses specific mechanisms to cope with growth under low DO concentrations and high nitrite concentrations. These mechanisms are additionally influenced by the physiological growth state of N. europaea cultures and are possibly geared to enable more efficient substrate utilization or nitrite detoxification.

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

    OpenAIRE

    Flynn John T; Ruhlen Rachel L; Hewett John E; Qin Wenyi; Sauter Edward R; Rottinghaus George; Chen Yin-Chieh

    2008-01-01

    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 (PG)E2 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...

  12. Comparison of OH concentration measurements by DOAS and LIF during SAPHIR chamber experiments at high OH reactivity and low NO concentration

    OpenAIRE

    Fuchs, H.; H.-P. Dorn; Bachner, M.; Bohn, B.; Brauers, T.; Gomm, S.; Hofzumahaus, A; F. Holland; Nehr, S.; Rohrer, F.; Tillmann, R.; Wahner, A.

    2012-01-01

    During recent field campaigns, hydroxyl radical (OH) concentrations that were measured by laser-induced fluorescence (LIF) were up to a factor of ten larger than predicted by current chemical models for conditions of high OH reactivity and low NO concentration. These discrepancies, which were observed in forests and urban-influenced rural environments, are so far not entirely understood. In summer 2011, a series of experiments was carried out in the atmosphere simulation chamber SAPHIR in Jül...

  13. Adsorption of benzene, cyclohexane and hexane on ordered mesoporous carbon.

    Science.gov (United States)

    Wang, Gang; Dou, Baojuan; Zhang, Zhongshen; Wang, Junhui; Liu, Haier; Hao, Zhengping

    2015-04-01

    Ordered mesoporous carbon (OMC) with high specific surface area and large pore volume was synthesized and tested for use as an adsorbent for volatile organic compound (VOC) disposal. Benzene, cyclohexane and hexane were selected as typical adsorbates due to their different molecular sizes and extensive utilization in industrial processes. In spite of their structural differences, high adsorption amounts were achieved for all three adsorbates, as the pore size of OMC is large enough for the access of these VOCs. In addition, the unusual bimodal-like pore size distribution gives the adsorbates a higher diffusion rate compared with conventional adsorbents such as activated carbon and carbon molecular sieve. Kinetic analysis suggests that the adsorption barriers mainly originated from the difficulty of VOC vapor molecules entering the pore channels of adsorbents. Therefore, its superior adsorption ability toward VOCs, together with a high diffusion rate, makes the ordered mesoporous carbon a promising potential adsorbent for VOC disposal. PMID:25872710

  14. On concentration dependences of critical temperature and isotopic effect index in high-Tc superconductors

    International Nuclear Information System (INIS)

    It is shown that nonmonotonous concentrational dependences of Tc and the isotopic (with respect to oxygen) index ?0 experimentally observed in high-Tc superconductors can be explained in terms of 'plasma' mechanism of superconductivity in layered metal with two-dimensional narrow-zone. A possible explanation of a positive sign of the Tc derivative with respect to pressure in the new compound HgBaCaCuO with Tc > 130 K is proposed

  15. Status of Ultra-High Concentrator Multijunction Solar Cell Development at IES-UPM.

    OpenAIRE

    Rey-stolle Prado, Ignacio; Algora del Valle, Carlos; Barrigón Montañés, Enrique; Garcia Tabares Valdivieso, Elisa; García Vara, Iván; Espinet González, Pilar

    2010-01-01

    After the successful implementation of a record performing dual-junction solar cell at ultra high concentration, in this paper we present the optimization of key aspects in the transition to a triple-junction device, namely the hetero nucleation of III-V structures onto germanium substrates. This optimization is based on in-situ RAS measurements during the MOVPE growth of the triple-junction solar cell structure and subsequent AFM analysis. The correlation between RAS and AFM allows detecting...

  16. Safety issues of high-concentrated hydrogen peroxide production used as rocket propellant

    Science.gov (United States)

    Romantsova, O. V.; Ulybin, V. B.

    2015-04-01

    The article dwells on the possibility of production of high-concentrated hydrogen peroxide with the Russian technology of isopropyl alcohol autoxidation. Analysis of fire/explosion hazards and reasons of insufficient quality is conducted for the technology. Modified technology is shown. Non-standard fire/explosion characteristics required for integrated fire/explosion hazards rating for modified hydrogen peroxide production based on the autoxidation of isopropyl alcohol are defined.

  17. Bubble columns for condensation at high concentrations of noncondensable gas: Heat-transfer model and experiments

    OpenAIRE

    Narayan, G. Prakash; Sharqawy, Mostafa H.; Lam, Steven; Das, Sarit K.; Lienhard, John H.

    2012-01-01

    Carrier gas based thermodynamic cycles are common in water desalination applications. These cycles often require condensation of water vapor out of the carrier gas stream. As the carrier gas is most likely a noncondensable gas present in very high concentrations (60–95%), a large additional resistance to heat transfer is present. It is proposed to reduce the aforementioned thermal resistance by condensing the vapor–gas mixture in a column of cold liquid rather than on a cold surface using...

  18. High glucose concentration in isotonic media alters Caco-2 cell permeability

    OpenAIRE

    Souza, Vanessa M. D; Shertzer, Howard G.; Menon, Anil G.; Pauletti, Giovanni M.

    2003-01-01

    Caco-2 cell permeability was evaluated in isotonic media containing high (25mM) or physiological (5.5mM) glucose concentrations. Transepithelial electrical resistance (TEER) and membrane fluidity were measured to assess glucose-induced alterations in physical barrier properties. In parallel, distribution of the actin filament (F-actin) and zonula occludens-1 (ZO-1) proteins was assessed by confocal microscopy. Transepithelial fluxes of mannitol, hydrocortisone, digoxin, and glycyl sarcosine (...

  19. The Effects of Nickel Concentration on Heat-Treated High-Speed Steel Magnetoelastic Torque Transducers

    Science.gov (United States)

    Franklin, Doug; Gordon, Ryan; Orris, Jason; Boley, Mark

    2003-03-01

    We have previously determined that a ferromagnetic high-speed maraging steel alloy of 18as C250) is one of the best materials for use in the construction of a "ring type" torque sensor on a non-ferromagnetic shaft used for power transmission applications. We created two distinct portions of the ring in which a high degree of oppositely polarized circumferential magnetization was maintained with a saturated alignment of the magnetic domains due to the high circumferential coercive force. Transducer sensitivities (field signal per applied torque) range from 14 - 31 mG/N-m following appropriate heat treatments of these rings. However, in many applications where a sensory ring would be impractical, the same type of magnetic arrangement, albeit with slightly lower sensitivities, can also be produced in a hollow ferromagnetic high-speed steel "shaft type" torque sensor. However, much lower nickel concentrations are required to prevent the shafts from being too brittle for most torque transfer applications; the downside of this is that we have found the transducer sensitivities to dramatically decrease with the nickel concentration. The three steel shafts we investigated had respective nickel concentrations of 0.20steel types W-1, O-1, and Kapstar. Their transducer sensitivities were found as 1.5, 5.5, and 8.5 mG/N-m, respectively, and also exhibited slight increases following the standard heat treatments of the steel. The area of the axial hysteresis curves for these three steels was found to decrease with nickel concentration, with relatively little change in the circumferential.

  20. MEASURING NICOTINE INTAKE AMONG HIGHLY DEPENDENT ADOLESCENT SMOKERS: COMPARABILITY OF SALIVA AND PLASMA COTININE CONCENTRATIONS

    OpenAIRE

    Parzynski, Craig S.; Jaszyna-Gasior, Maria; Franken, Frederick H.; Moolchan, Eric T.

    2007-01-01

    Cotinine is the most common biomarker used to assess nicotine exposure and abstinence. It can be measured in various matrices including saliva, plasma, and urine. Previous research with adults has shown high correlations between saliva and plasma cotinine concentrations. However, research has not examined this relationship in adolescents. Additionally, variability in saliva flow and metabolism across gender, ethnicity, and age may impact the relationship between saliva and plasma cotinine con...

  1. Measured and modelled cloud condensation nuclei concentration at the high alpine site Jungfraujoch

    OpenAIRE

    Z. Jurányi; M. Gysel; Weingartner, E.; P. F. DeCarlo; Kammermann, L.; Baltensperger, U.

    2010-01-01

    Atmospheric aerosol particles are able to act as cloud condensation nuclei (CCN) and are therefore important for the climate and the hydrological cycle, but their properties are not fully understood. Total CCN number concentrations at 10 different supersaturations in the range of SS = 0.12–1.18% were measured in May 2008 at the remote high alpine research station, Jungfraujoch, Switzerland (3580 m asl.). In this paper, we present a closure study between measured and predi...

  2. Fluorescent carbon nanoparticles synthesized from benzene by electric plasma discharge

    Science.gov (United States)

    Chaudhary, R.; Varadarajan, V.; Mohanty, S. K.; Koymen, A. R.

    2011-03-01

    Various allotropes of Carbon nanoparticles (CNP) are emerging as very important building blocks for nanotechnology and biomedical applications due to their unique electronic, optical, mechanical and thermal properties. We report synthesis of crystalline CNPs from benzene using electric plasma discharge method under controlled laboratory environment. With varied electric field, different allotropes of carbon were synthesized as observed under high resolution electron microscope and selected area electron diffraction, optical spectroscopic studies revealed distinct differences between these CNPs. Raman spectroscopy of these CNPs showed a distinct peak at 1330 cm-1 (characteristic of defect band) and another peak at 1600 cm-1 (graphitic band). The ratio of defect to graphitic band was found to increase with increasing voltage between Fe-electrodes. Further, the ratio was altered when CNPs were formed using graphite-electrodes. Fluorescence spectroscopic measurements showed evident blue fluorescence exhibited by CNPs formed at relatively higher voltage between two Fe-electrodes. This was attributed to the increasing Fe-content, as measured by Energy dispersive X-ray analysis (EDX) and vibrating sample magnetometer (VSM). Addition of exogenous dyes in benzene during synthesis of CNPs using electric plasma discharge led to formation of fluorescent nanotubes. These fluorescent CNPs can be functionalized to target cancer cells for both imaging and targeted photothermal therapy using near-IR laser beam.

  3. Synthesis of polycationic bentonite-ionene complexes and their benzene adsorption capacity

    Scientific Electronic Library Online (English)

    Valquíria, Campos; Celize Maia, Tcacenco.

    2015-04-01

    Full Text Available The purpose of this work was to structurally modify clays in order to incorporate water-insoluble molecules, such as petroleum hydrocarbons. The potential for ion exchange of quaternary ammonium salts was studied, which revealed their ability to interact with anions on the cationic surface, for envi [...] ronmental applications of the material. Ionenes, also known as polycations, have many potential uses in environmental applications. In this work, cationic aliphatic ammonium polyionenes, specifically 3,6-ionene and 3,6-dodecylionene, were prepared for incorporation into clay to form bentonite-ionene complexes. The intercalation of bentonite with ionene polymers resulted in an increase in the basal spacing of 3,6-dodecylionene from 1.5-3.5 nm. The higher d001 spacing of 3,6-dodecylionene samples than that of 3,6-ionene samples may be attributed to their longer tail length. The behavior of the TG/DTG curves and the activation energy values suggest that 3,6-dodecylionene (E = 174.85 kJ mol–1) is thermally more stable than 3,6 ionene (E = 115.52 kJ mol–1) complexes. The adsorption of benzene by 3,6-ionene and 3,6-dodecylionene was also investigated. The increase in benzene concentrations resulted in increased benzene adsorption by the sorbents tested in this work. The sorption capacity of benzene on ionene-modified bentonite was in the order of 3,6-dodecylionene > 3,6-ionene.

  4. Benzene metabolite levels in blood and bone marrow of B6C3F{sub 1} mice after low-level exposure

    Energy Technology Data Exchange (ETDEWEB)

    Bechtold, W.E.; Strunk, M.R.; Thornton-Manning, J.R. [and others

    1995-12-01

    Studies at the Inhalation Toxicology Research Institute (ITRI) have explored the species-specific uptake and metabolism of benzene. Results have shown that metabolism is dependent on both dose and route of administration. Of particular interest were shifts in the major metabolic pathways as a function of exposure concentration. In these studies, B6C3F{sub 1} mice were exposed to increasing levels of benzene by either gavage or inhalation. As benzene internal dose increased, the relative amounts of muconic acid and hydroquinone decreased. In contrast, the relative amount of catechol increased with increasing exposure. These results show that the relative levels of toxic metabolites are a function of exposure level. Based on these results and assuming a linear relationship between exposure concentration and levels of bone marrow metabolites, it would be difficult to detect an elevation of any phenolic metabolites above background after occupational exposures to the OSHA Permissible Exposure Limit of 1 ppm benzene.

  5. Ge doped GaN with controllable high carrier concentration for plasmonic applications

    Energy Technology Data Exchange (ETDEWEB)

    Kirste, Ronny; Hoffmann, Marc P.; Sachet, Edward; Bobea, Milena; Bryan, Zachary; Bryan, Isaac; Maria, Jon-Paul; Collazo, Ramón; Sitar, Zlatko [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695-7919 (United States); Nenstiel, Christian; Hoffmann, Axel [Institut f?r Festkörperphsyik, TU-Berlin, Hardenbergstrasse 36, 10623 Berlin (Germany)

    2013-12-09

    Controllable Ge doping in GaN is demonstrated for carrier concentrations of up to 2.4?×?10{sup 20} cm{sup ?3}. Low temperature luminescence spectra from the highly doped samples reveal band gap renormalization and band filling (Burstein-Moss shift) in addition to a sharp transition. Infrared ellipsometry spectra demonstrate the existence of electron plasma with an energy around 3500?cm{sup ?1} and a surface plasma with an energy around 2000?cm{sup ?1}. These findings open possibilities for the application of highly doped GaN for plasmonic devices.

  6. Implications of Industrial Processing Strategy on Cellulosic Ethanol Production at High Solids Concentrations

    DEFF Research Database (Denmark)

    Cannella, David

    2013-01-01

    The production of cellulosic ethanol is a biochemical process of not edible biomasses which contain the cellulose. The process involves the use of enzymes to hydrolyze the cellulose in fermentable sugars to finally produce ethanol via fermentative microorganisms (i.e. yeasts). These biomasses are the leftover of agricultural productions (straws), not edible crops (giant reed) or wood, thus the ethanol so produced is also called second generation (or 2G ethanol), which differs from the first generation produced from starch (sugar beets mostly). In the industrial production of cellulosic ethanol high solids strategy resulted critical for its cost effectiveness: high concentration of initial biomass it will lead to high concentration of the final product (ethanol), thus more convenient to isolate. This thesis investigate the implementation of a high solids loading concept into cellulosic ethanol technology using new enzymatic cellulolytic cocktails, and how a high solids setup may affect the overall process design. The thesis focuses on two main biomasses: an agricultural feedstock such as wheat straw and a woody feedstock such as Norwegian spruce. The best performing strategy for cellulosic ethanol fermentation at high solids loading, in terms of maximized final conversion yield, is the overall aim of the work conducted. This thesis also revisits the knowledge already acquired in light of new enzymatic activities recently discovered i.e. lytic polysaccharides mono oxygenases (LPMOs), and how these ffects cellulosic ethanol processing at high solids conditions. Moreover for the first time in literature the activity of LPMOs on real lignocellulosic substrate and during cellulosic ethanol production is characterized. Hence describing the enzymatic scale dynamics when resembling in planta conditions, i.e. environments resembling the natural conditions of lignocellulose as substrate a d high dry matter. This can in turn lead to a better understanding of what could happen and be optimized while designing a reactor fora high solids environment

  7. Combustion Processes Indoors: a Source of High OH Radical Concentrations Through the Photolysis of Hono

    Science.gov (United States)

    Bartolomei, V.; Gomez Alvarez, E.; Glor, M.; Gligorovski, S.; Temime-Roussel, B.; Quivet, E.; Strekowski, R.; Zetzsch, C.; Held, A. B.; Wortham, H.

    2013-12-01

    Hydroxyl radical (OH) is one of the most important oxidant species in the atmosphere controlling its self-oxidizing capacity. The main sources of OH radicals are photolysis of ozone and photolysis of nitrous acid (HONO), among the others. In the indoor air, the ozonolysis of alkenes has been suggested as the main OH formation pathway. The possibility for OH formation through photolytic pathways in the indoor environment has been, up to now, ignored (Gómez Alvarez et al., 2012). Models and indirect measurements to the present time predicted concentrations of OH radicals in the order of 104 -105 cm-3. Recently, by direct measurements we have detected high OH radical concentrations of 1.8 106 cm-3 in a classroom in Marseille and we demonstrated that its main source is the photolysis of HONO (Gómez Alvarez et al., 2013). The concentrations of HONO are quite high indoors, reaching levels in the order of a few tens of ppbV (Gómez Alvarez et al., 2013). This is mainly due to 1) direct combustion sources and 2) heterogeneous reactions of NO2 on the numerous surfaces present in the indoor environment. HONO levels of 30 ppb were measured in a previous campaign carried out in Bayreuth in July 2012 as direct emissions from the combustion of a candle. The combination between so high concentrations of HONO and higher than expected light transmissions indoors (or indoor artificial lighting) could have a significant impact on the OH concentrations indoors which could feasibly become considerably higher than we measured in our school campaign (Gomez Alvarez et al., 2013). In order to evaluate these upper limits under combustion conditions in the indoor environment, we have carried out a campaign in the LOTASC chamber (Bayreuth, Germany). For this aim, the exhaust fumes from the burning of a commonly used domestic candle have been introduced in the chamber. The chamber was irradiated under well research indoor lighting conditions. A thorough characterization of light intensities and span (wavelength distribution) indoors have been performed, which had been identified as a clear flaw in our knowledge restricting the advancement of indoor air quality models. OH concentration levels have been determined using d9-butanol as tracer, using the OH clock determination procedure by PTR-MS-TOF. The OH radical concentration was investigated using different light intensities representative from indoor conditions, both natural and artificial and also different levels of RH. The PSS model has been performed in order to evaluate the contribution of different sources to the OH radical concentrations indoors under these conditions. The obtained results from the PSS model clearly indicate that the main source of OH radical indoors under combustion conditions is the photolysis of HONO under typical indoor irradiation conditions. REFERENCES Gómez Alvarez E, Wortham H, Strekowski R, Zetzsch C, Gligorovski S (2012) Atmospheric photo-sensitized heterogeneous and multiphase reactions: From outdoors to indoors, Environ. Sci. Technol. 46, 1955-1963. Gómez Alvarez, E.; Amedro, D.; Afif, C. ; Gligorovski, S.; Schoemacker , C.; Fittschen, C. ; Doussin, J. F.; Wortham, H. (2013) Unexpectedly high indoor hydroxyl radical concentrations associated with nitrous acid. Proc. Natl. Acad. Sci. USA Accepted.

  8. High-efficiency atomic entanglement concentration for quantum communication network assisted by cavity QED

    Science.gov (United States)

    Wang, Guan-Yu; Li, Tao; Deng, Fu-Guo

    2015-04-01

    Quantum entanglement is the key resource in quantum information processing, especially in quantum communication network. However, affected by the environment noise, the maximally entangled states usually collapse into nonmaximally entangled ones or even mixed states. Here we present two high-efficiency schemes to complete the entanglement concentration of nonlocal two-atom systems. Our first scheme is used to concentrate the nonlocal atomic systems in the partially entangled states with known parameters, and it has the optimal success probability. The second scheme is used to concentrate the entanglement of the nonlocal two-atom systems in the partially entangled states with unknown parameters. Compared with the other schemes for the entanglement concentration of atomic systems, our two protocols are more efficient and practical. They require only an ancillary single photon to judge whether they succeed or not, and they work in a heralded way with detection inefficiency and absence of sophisticated single-photon detectors in practical applications. Moreover, they are insensitive to both the cavity decay and atomic spontaneous emission.

  9. Time evolution of atmospheric particle number concentration during high-intensity pyrotechnic events

    Science.gov (United States)

    Crespo, Javier; Yubero, Eduardo; Nicolás, Jose F.; Caballero, Sandra; Galindo, Nuria

    2014-10-01

    The Mascletàs are high-intensity pyrotechnic events, typical of eastern Spanish festivals, in which thousands of firecrackers are burnt at ground level in an intense, short-time (<8 min) deafening spectacle that generates short-lived, thick aerosol clouds. In this study, the impact of such events on air quality has been evaluated by means of particle number concentration measurements performed close to the venue during the June festival in Alicante (southeastern Spain). Peak concentrations and dilution times observed throughout the Mascletàs have been compared to those measured when conventional aerial fireworks were launched 2 km away from the monitoring site. The impact of the Mascletàs on the total number concentration of particles larger than 0.3 ?m was higher (maximum ˜2·104 cm-3) than that of fireworks (maximum ˜2·103 cm-3). The effect of fireworks depended on whether the dominant meteorological conditions favoured the transport of the plume to the measurement location. However, the time required for particle concentrations to return to background levels is longer and more variable for firework displays (minutes to hours) than for the Mascletàs (<25 min).

  10. High fetal plasma adenosine concentration: a role for the fetus in preeclampsia?

    LENUS (Irish Health Repository)

    Espinoza, Jimmy

    2012-02-01

    OBJECTIVE: Clinical observations suggest a role for the fetus in the maternal manifestations of preeclampsia, but the possible signaling mechanisms remain unclear. This study compares the fetal plasma concentrations of adenosine from normal pregnancies with those from preeclampsia. STUDY DESIGN: This secondary data analysis included normal pregnancies (n = 27) and patients with preeclampsia (n = 39). Patients with preeclampsia were subclassified into patients with (n = 25) and without (n = 14) abnormal uterine artery Doppler velocimetry (UADV). RESULTS: Fetal plasma concentrations of adenosine were significantly higher in patients with preeclampsia (1.35 +\\/- 0.09 mumol\\/L) than in normal pregnancies (0.52 +\\/- 0.06 mumol\\/L; P < .0001). Fetal plasma concentrations of adenosine in patients with preeclampsia with abnormal UADV (1.78 +\\/- 0.15 mumol\\/L), but not with normal UADV (0.58 +\\/- 0.14 mumol\\/L), were significantly higher than in normal pregnancies (P < .0001). CONCLUSION: Patients with preeclampsia with sonographic evidence of chronic uteroplacental ischemia have high fetal plasma concentrations of adenosine.

  11. Static high-irradiance solar concentration by gradient-index optics

    Science.gov (United States)

    Kotsidas, Panagiotis; Modi, Vijay; Gordon, Jeffrey M.

    2011-10-01

    Novel solutions for realistic gradient-index (GRIN) lenses are presented, that create the possibility of nominally stationary photovoltaic concentrators capable of daylong averaged flux concentration levels of order 103. One transfers the burden of precision solar tracking from massive units on which numerous solar modules are mounted, to miniaturized mechanical components inside modules that are completely stationary. The best optical properties for this aim would appear to be perfect imaging - a case where imaging and nonimaging objectives coalesce because perfect imaging is non-trivially synonymous with attaining the fundamental limit to concentration. Our GRIN profiles surmount limitations of classical Luneburg solutions that resulted in GRIN lenses being deemed physically unattainable idealizations for sunlight. To wit, while preserving perfect imaging, our GRIN profiles eliminate the need for refractive indices near unity, markedly reduce the range of refractive indices required, and permit arbitrary focal length. They are also amenable to realistic materials and fabrication technologies. Raytrace simulations confirm that they offer an unprecedented solution to this problem - even accounting for chromatic aberration and misalignment. Eliminating massive precision tracking of large photovoltaic arrays in favor of precision cm-scale lens tracking inside the modules opens the possibility of rooftop CPV. The perception that high solar concentration is inseparably linked to massive trackers is supplanted here by a different paradigm.

  12. High-efficiency atomic entanglement concentration for quantum communication network assisted by cavity QED

    Science.gov (United States)

    Wang, Guan-Yu; Li, Tao; Deng, Fu-Guo

    2015-02-01

    Quantum entanglement is the key resource in quantum information processing, especially in quantum communication network. However, affected by the environment noise, the maximally entangled states usually collapse into nonmaximally entangled ones or even mixed states. Here we present two high-efficiency schemes to complete the entanglement concentration of nonlocal two-atom systems. Our first scheme is used to concentrate the nonlocal atomic systems in the partially entangled states with known parameters, and it has the optimal success probability. The second scheme is used to concentrate the entanglement of the nonlocal two-atom systems in the partially entangled states with unknown parameters. Compared with the other schemes for the entanglement concentration of atomic systems, our two protocols are more efficient and practical. They require only an ancillary single photon to judge whether they succeed or not, and they work in a heralded way with detection inefficiency and absence of sophisticated single-photon detectors in practical applications. Moreover, they are insensitive to both the cavity decay and atomic spontaneous emission.

  13. The ability of fungus Mucor racemosus Fresenius to degrade high concentration of detergent

    Directory of Open Access Journals (Sweden)

    Jakovljevi? Violeta D.

    2014-01-01

    Full Text Available The ability of fungus Mucor racemosus Fresenius to decompose high concentration of commercial detergent (MERIX, Henkel, Serbia was investigated in this study. Fungus was cultivated in liquid growth medium by Czapek with addition of detergent at concentration 0.5% during 16 days. The biochemical changes of pH, redox potential, amount of free and total organic acids, and activity of alkaline phosphatase were evaluated by analysis of fermentation broth. Simultaneously, biodegradation percentage of anionic surfactant of tested detergent was confirmed by MBAS assay. At the same time, the influence of detergent on fungal growth and total dry weight biomass was determined. Detergent at concentration 0.5% influenced on decreasing of pH value and increasing of redox potential as well as increasing of free and total organic acids. Enzyme activity of alkaline phosphatase was reduced by detergent at concentration 0.5%. The fungus was decomposed about 62% of anionic surfactant during 16 day. Due to fungus was produced higher dry weight biomass (53% in relation to control. [Projekat Ministarstva nauke Republike Srbije, br. III 43004

  14. Multinomial logistic regression model to assess the levels in trans, trans-muconic acid and inferential-risk age group among benzene-exposed group

    OpenAIRE

    Mala A; Ravichandran B; Raghavan S; Rajmohan H

    2010-01-01

    There are only a few studies performed on multinomial logistic regression on the benzene-exposed occupational group. A study was carried out to assess the relationship between the benzene concentration and trans-trans-muconic acid (t,t-MA), biomarkers in urine samples from petrol filling workers. A total of 117 workers involved in this occupation were selected for this current study. Generally, logistic regression analysis (LR) is a common statistical technique that could be used to predict t...

  15. Interaction of mono-carboxylic acids in benzene studied by small-angle neutron scattering

    OpenAIRE

    Petrenko, Viktor I.; Avdeev, Mikhail V.; Almásy, László; Bulavin, Leonid A.; Aksenov, Victor L.; Rosta, László; Garamus, Vasil M.

    2009-01-01

    The intermolecular interaction of non-saturated (oleic acid) and saturated (stearic and myristic acids) mono-carboxylic acids in a non-polar organic solvent (deuterated benzene) is derived from the concentration dependence of the small-angle neutron scattering. The excluded volume repulsion dominates over the attraction (supposed due to van der Waals forces) for oleic and myristic acids. In turn, for stearic acid the attractive component is higher than the repulsive one; this results in a shi...

  16. Setting of French indoor air quality guidelines for chronic exposure to benzene

    OpenAIRE

    Keirsbulck, Marion; Bonvallot, Nathalie; Mandin, Corinne; Kirchner, Séverine; Dor, Frédéric; Rousselle, Christophe

    2009-01-01

    Indoor air quality guidelines (IAQGs) provide safe levels of indoor pollutant concentrations below which adverse health effects are not expected to occur in the general population, including susceptible groups. The development of French IAQGs has been on-going since 2005 in the framework of the National Environment and Health Action Plan (NEHAP, 2004-2008). According to toxicological and epidemiological data, benzene inhalation leads to acute and chronic effects. For long-term exposure, haema...

  17. Chemical Dosimetry by Chromatography of a Water/Benzene/Phenol Mixture

    International Nuclear Information System (INIS)

    Phenol is produced by subjecting a benzene-saturated water sample to gamma radiation. The concentration of the phenol is proportional to the integrated flux. Chromatographic determination of the phenol in the gaseous phase makes it possible to work with very small quantities of liquid. It is thus possible to make pinpoint measurements, and this constitutes an additional advantage of the method, over and above the greater convenience afforded by chromatography in the gaseous phase. (author)

  18. Benzene exposure: An overview of monitoring methods and their findings

    OpenAIRE

    Weisel, Clifford P.

    2010-01-01

    Benzene has been measured throughout the environment and is commonly emitted in several industrial and transportation settings leading to widespread environmental and occupational exposures. Inhalation is the most common exposure route but benzene rapidly penetrates the skin and can contaminant water and food resulting in dermal and ingestion exposures. While less toxic solvents have been substituted for benzene, it still is a component of petroleum products, including gasoline, and is a trac...

  19. The solubilities of benzene polycarboxylic acids in water

    International Nuclear Information System (INIS)

    The solubilities in water of all benzene polycarboxylic acids are discussed, using data determined in this work (benzoic, terephthalic, trimellitic, trimesic, and pyromellitic acids) and available from the literature (benzoic, phthalic, isophthalic, terephthalic, hemimellitic, trimelitic, trimesic, mellophanic, prehnitic, pyromellitic, benzene-pentacarboxylic and mellitic acids). The apparent molar enthalpies of solution at the saturation point for these benzene polycarboxylic acids were determined from the temperature dependence of the solubilities

  20. Benzene, the Exposome and Future Investigations of Leukemia Etiology

    OpenAIRE

    Smith, Martyn T.; Zhang, Luoping; Mchale, Cliona M.; Skibola, Christine F.; Rappaport, Stephen M.

    2011-01-01

    Benzene exposure is associated with acute myeloid leukemia (AML), myelodysplastic syndromes (MDS), and probably lymphoma and childhood leukemia. Biological plausibility for a causal role of benzene in these diseases comes from its toxicity to hematopoietic stem cells (HSC) or progenitor cells, from which all leukemias and related disorders arise. The effect of this toxicity is manifest as lowered blood counts (hematotoxicity), even in individuals occupationally exposed to low levels of benzen...

  1. [Plasma concentration of C-reactive protein in patients with high estrogen levels].

    Science.gov (United States)

    Ricoux, R; Pontet, M; Tresca, J P; Engler, R

    1994-01-01

    The monitoring of inflammatory activity in patients with a high level of estrogen is controversial because the significance of a raised estradiol level on C-reactive protein (CRP) concentrations is a debated question. This prompted us to assay CRP by a sensitive Elisa in a sample of 30 patients with ovarian stimulation for in vitro fertilization, thus with high levels of estradiol. For 15 of these women, six to nine plasma samples were analyzed allowing a kinetic study of plasma levels of CRP, estradiol and sex steroid-binding plasma protein (SBP). No significant correlation was found between the concentrations of estradiol and CRP for the 30 patients. In the kinetic study, as mean estradiol levels rose exponentially from 50 to 1400 ng/l between day 5 and 14, the CRP level tended to vary markedly from one patient to another and sometimes from day to day, but there was never any relation with estradiol level. Furthermore, CRP did not significantly modify the slope of the regression line between estradiol concentration and the day of the menstrual cycle. In contrast, the effect of estradiol on SBP was clear, which supports the absence of estradiol effect on CRP level. PMID:7802339

  2. Enzymatic synthesis of fructooligosaccharides with high 1-kestose concentrations using response surface methodology.

    Science.gov (United States)

    Vega, Roberto; Zúniga-Hansen, M E

    2011-11-01

    Response surface methodology was used as an optimization tool for the production of short chain fructooligosaccharides (sc-FOS) using the commercial cellulolytic enzyme preparation, Rohapect CM. Three independent variables, temperature, concentrations of sucrose and enzyme were tested in the reaction medium. The responses of the design were, yield (gsc-FOS/100 g initial sucrose), 1-kestose (g/100 g sc-FOS) and volumetric productivity (gsc-FOS/Lh). Significant effects on the three responses included a quadratic effect (temperature), a linear effect (sucrose and enzyme concentrations) and an interaction between temperature and sucrose concentration. The cost-effective conditions to support the process in a high competitive market were 50 °C, 6.6 TU/mL enzyme, 2.103 M sucrose in 50 mM acetate buffer at pH 5.5, and the synthesis for a 5 h reaction time. Under these conditions, a high YP/S (63.8%), QP (91.9 g/Lh) and sGF2 (68.2%) was achieved. PMID:21974879

  3. Concomitant Raman spectroscopy and dynamic light scattering for characterization of therapeutic proteins at high concentrations.

    Science.gov (United States)

    Zhou, Chen; Qi, Wei; Lewis, E Neil; Carpenter, John F

    2015-03-01

    A Raman spectrometer and dynamic light scattering system were combined in a single platform (Raman-DLS) to provide concomitant higher order structural and hydrodynamic size data for therapeutic proteins at high concentration. As model therapeutic proteins, we studied human serum albumin (HSA) and intravenous immunoglobulin (IVIG). HSA concentration and temperature interval during heating did not affect the onset temperatures for conformation perturbation or aggregation. The impact of pH on thermal stability of HSA was tested at pHs 3, 5, and 8. Stability was the greatest at pH 8, but distinct unfolding and aggregation behaviors were observed at the different pHs. HSA structural transitions and aggregation kinetics were also studied in real time during isothermal incubations at pH 7. In a forced oxidation study, it was found that hydrogen peroxide (H2O2) treatment reduced the thermal stability of HSA. Finally, the structure and thermal stability of IVIG were studied, and a comprehensive characterization of heating-induced structural perturbations and aggregation was obtained. In conclusion, by providing comprehensive data on protein tertiary and secondary structures and hydrodynamic size during real-time heating or isothermal incubation experiments, the Raman-DLS system offers unique physical insights into the properties of high-concentration protein samples. PMID:25475399

  4. High Efficiency Nanostructured III-V Photovoltaics for Solar Concentrator Application

    Energy Technology Data Exchange (ETDEWEB)

    Hubbard, Seth

    2012-09-12

    The High Efficiency Nanostructured III-V Photovoltaics for Solar Concentrators project seeks to provide new photovoltaic cells for Concentrator Photovoltaics (CPV) Systems with higher cell efficiency, more favorable temperature coefficients and less sensitivity to changes in spectral distribution. The main objective of this project is to provide high efficiency III-V solar cells that will reduce the overall cost per Watt for power generation using CPV systems.This work is focused both on a potential near term application, namely the use of indium arsenide (InAs) QDs to spectrally "tune" the middle (GaAs) cell of a SOA triple junction device to a more favorable effective bandgap, as well as the long term goal of demonstrating intermediate band solar cell effects. The QDs are confined within a high electric field i-region of a standard GaAs solar cell. The extended absorption spectrum (and thus enhanced short circuit current) of the QD solar cell results from the increase in the sub GaAs bandgap spectral response that is achievable as quantum dot layers are introduced into the i-region. We have grown InAs quantum dots by OMVPE technique and optimized the QD growth conditions. Arrays of up to 40 layers of strain balanced quantum dots have been experimentally demonstrated with good material quality, low residual stain and high PL intensity. Quantum dot enhanced solar cells were grown and tested under simulated one sun AM1.5 conditions. Concentrator solar cells have been grown and fabricated with 5-40 layers of QDs. Testing of these devices show the QD cells have improved efficiency compared to baseline devices without QDs. Device modeling and measurement of thermal properties were performed using Crosslight APSYS. Improvements in a triple junction solar cell with the insertion of QDs into the middle current limiting junction was shown to be as high as 29% under one sun illumination for a 10 layer stack QD enhanced triple junction solar cell. QD devices have strong potential for net gains in efficiency at high concentration.

  5. Combined effects of simultaneous ?-rays irradiation and inhalation of benzene, toluene and carbon monoxide on rabbits

    International Nuclear Information System (INIS)

    Combined effects on rabbits induced by ?-rays irradiation in combination with inhalation of benzene, toluene and carbon monoxide and the interactive characteristics (antagonistic, additive or synergistic) of these agents were studied. Ninety healthy male rabbits were equally divided into 9 groups, eight of which were test groups assigned according to four factor- two-dose-level orthogonal layout [L8(27)] program and one was the control. The two dose-levels of the four factors were: for ?-rays irradiation, 0.0075 Gy/d and 0.0375 Gy/d, and for benzene, toluene and carbon monoxide, 40 +- 15 mg/m3 and 182 +- 33 mg/m3, 90 +- 30 mg/m3 and 407 +- 68 mg/m3, 93 +- 4 mg/m3 and 278 +- 8 mg/m3 respectively. The animals were exposed to ?-rays irradiation combined with benzene, toluene and CO vapor 2h a day and 5 days a week for a period of 8 weeks. Experimental results were analysed with the method of variance analysis and the test groups were compared. The results showed that (1) the interactive factor, the ratio (?) of the combined effects caused by the four agents to the sum of the four independent effects induced by those agents, was 2.16, 1.58, 2.07, 2.67, 1.31 and 1.18 for dicentric + ring, acentric, aberration cells, total aberration, micronuclei and SCEs/C in lymphocytes respectively, and the ratio for aberrant sperms was as high as 5.97. The ratios showed that interactions were maitios showed that interactions were mainly synergistic (? > 1). However, for acentric interactions between ?-rays and benzene was antagonistic. (2) The four agents could all obviously cause decrease in testis weight index, and ?-rays, benzene and CO could markedly reduce the number of sperms and increase the ratio of aberrant sperms. The interactions between ?-rays and benzene for the decrease in testis weight index and for the elevation of the ratio of aberrant sperms were synergistic. (3) CO could cause decrease in total amount of leucocytes, thrombocytes and hemoglobin, and toluene cause decrease in lymphocytes. (4) Gamma rays irradiation combined with inhalation of benzene, toluene and CO could produce significant interactions which were mainly synergistic, and CO, when combined with ?-rays, benzene and toluene, could cause obvious effects on gland

  6. Quality control of mitigation methods for unusually high indoor radon concentrations.

    Science.gov (United States)

    Huber, J; Ennemoser, O; Schneider, P

    2001-08-01

    The present study's objective was to control the quality of different mitigation methods for unusually high indoor radon (222Rn) concentrations of up to 274,000 Bq m(-3) in a village (Umhausen, 2,600 inhabitants) in western Tyrol, Austria. Five years after mitigation, five different remedial actions were examined on their quality by means of measuring indoor radon concentrations with charcoal liquid scintillation radon detectors and with a continuously recording AlphaGuard detector. Mitigation method in house 1--a mechanical intake and outlet ventilation system with heat exchanger in the basement, combined with a soil depressurization system--was characterized by long-term stability. With most favorable air pressure (+100 Pa) in the basement, mean basement radon concentrations in the winter were reduced from 200,000 Bq m(-3) to 3,000 Bq m(-3) by this method 5 y after mitigation. Acting against experts' instructions, the inhabitants had switched off the ventilation system most of the time to minimize power consumption although it had been proven that ventilation reduced mean basement radon concentration by a factor of about 3 in the winter and about 15 in the summer. Mitigation method in house 2-soil depressurization with two fans and loops of drainage tubes to withdraw radon from the region below the floor and outside the basement walls, and from soil below that part of the house with no basement-had been the most successful remedial measure until the winter of 1999 (i.e., 6 y after mitigation), when micro-cracks opened and consequently mean basement radon concentration increased from 250 Bq m(-3) to 1,500 Bq m(-3). Measures to block these microcracks and to minimize soil drying are being developed. Five years after mitigation, the remedial method used in house 3--a multilayer floor construction, where a fan was used to suck radon from a layer between bottom slab and floor-reduced winter mean radon concentration from 25,000 Bq m(-3) to 1,200 Bq m(-3), with the ventilation on and the basement door open. Mitigation method in house 4--a basement sealing technique--was unsuccessful with almost identical radon concentrations during all the five years since mitigation had started. Mitigation method in house 5--a waterproof basement technique especially for future homes--reduced mean basement radon concentration below 300 Bq m(-3) and mean ground floor radon concentration below 200 Bq m(-3), which is the Austrian action level for newly constructed buildings. These findings indicate that even in areas with extremely high radon concentrations, effective mitigation of indoor radon can be achieved provided that house-specific long-term, stable mitigation techniques are applied. PMID:11480874

  7. Nicotine in High Concentration Causes Contraction of Isolated Strips of Rabbit Corpus Cavernosum

    Science.gov (United States)

    Nguyen, Hoai Bac; Lee, Shin Young; Park, Soo Hyun; Han, Jun Hyun

    2015-01-01

    It is well known that cigarette smoke can cause erectile dysfunction by affecting the penile vascular system. However, the exact effects of nicotine on the corpus cavernosum remains poorly understood. Nicotine has been reported to cause relaxation of the corpus cavernosum; it has also been reported to cause both contraction and relaxation. Therefore, high concentrations of nicotine were studied in strips from the rabbit corpus cavernosum to better understand its effects. The proximal penile corpus cavernosal strips from male rabbits weighing approximately 4 kg were used in organ bath studies. Nicotine in high concentrations (10-5~10-4 M) produced dose-dependent contractions of the corpus cavernosal strips. The incubation with 10-5 M hexamethonium (nicotinic receptor antagonist) significantly inhibited the magnitude of the nicotine associated contractions. The nicotine-induced contractions were not only significantly inhibited by pretreatment with 10-5 M indomethacin (nonspecific cyclooxygenase inhibitor) and with 10-6 M NS-398 (selective cyclooxygenase inhibitor), but also with 10-6 M Y-27632 (Rho kinase inhibitor). Ozagrel (thromboxane A2 synthase inhibitor) and SQ-29548 (highly selective TP receptor antagonist) pretreatments significantly reduced the nicotine-induced contractile amplitude of the strips. High concentrations of nicotine caused contraction of isolated rabbit corpus cavernosal strips. This contraction appeared to be mediated by activation of nicotinic receptors. Rho-kinase and cyclooxygenase pathways, especially cyclooxygenase-2 and thromboxane A2, might play a pivotal role in the mechanism associated with nicotine-induced contraction of the rabbit corpus cavernosum. PMID:25954131

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

    Directory of Open Access Journals (Sweden)

    Van Duong

    2014-03-01

    Full Text Available 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 concentrators (XCPCs are used to simulate their performance using CO2 as working fluid. For higher temperatures, a mathematical model is implemented to analyze the operating performance of a parabolic trough solar collector (PTC using CO2 at temperatures between 100°C and 600°C.

  9. Experimental design applied to photo-Fenton treatment of highly methomyl-concentrated water.

    Science.gov (United States)

    Micó, María M; Bacardit, Jordi; Sans, Carme

    2010-01-01

    This work is focused on the study of the suitability of the photo-Fenton process as a pretreatment for water highly contaminated with a methomyl commercial formulation in Advanced Greenhouses devices. Initial concentrations of reagents and pesticide were evaluated according to a central composite experimental design, with methomyl depletion and biocompatibility of the final effluent as response functions. A triad of optimal operation conditions could be determined, [Met.](0)=50 mg L(-1), [H(2)O(2)](0)=254 mg L(-1) and [Fe(2+)](0)=77 mg L(-1) for the best elimination yield and an acceptable BOD(5)/COD value, and initial concentration of methomyl can be established as the most important parameter for the performance of the treatment due to the limitations that impose on the hydrogen peroxide doses in the presence of the excipients of the commercial formulation. PMID:21045333

  10. Phenomenon of energy concentration in high-energy family events of cosmic rays

    CERN Document Server

    Wang He; Dai Zhi Qiang; Xue Liang; Feng Cun Feng; Zhang Xue Yao; Li Jin; Zhang Nai Jian; He Mao; Wang Cheng Rui; Ren Jing Ru; Lu Sui Ling

    2002-01-01

    The phenomenon of energy concentration in high-energy family events of cosmic rays is studied by comparing the results of family events of total visible energies 100-400 TeV observed in the Kanbala emulsion chamber experiment with the Monte Carlo simulation data. The simulation is made by the program CORSIKA in which QGSJET is applied as the hadronic interaction model, and the chemical composition of primary cosmic rays is obtained from the rigidity-cut model and the extrapolation of new results of direct measurements. This shows that the whole distribution tendency of the rate of energy concentration of simulated family events is basically consistent with that of the experiment

  11. Microscopic protein diffusion at high concentration by neutron spin-echo spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Le Coeur, C. [Laboratoire Leon Brillouin, CEA-CNRS, CEA Saclay, 91191 Gif-sur-Yvette (France); Longeville, S. [Laboratoire Leon Brillouin, CEA-CNRS, CEA Saclay, 91191 Gif-sur-Yvette (France)], E-mail: slongeville@cea.fr

    2008-04-18

    Molecular transport and reactions in biological cells are strongly affected by the presence of macromolecules at high concentration. We studied the intermolecular structure and diffusion of oxygen carriers myoglobin and hemoglobin in concentrated solutions using neutron diffraction and spin-echo spectroscopy. The self-diffusion coefficient measured by NSE spectroscopy is compatible with theoretical prediction for long-time self-diffusion coefficient for colloids. We measured I(q, t) for q {approx_equal} 1 A{sup -1} trying to observe the short-time diffusion coefficient. A signal which can be attributed to the protein is observed but which origin can neither be attributed to translational nor rotational diffusion.

  12. Growth characteristics of Botryococcus braunii 765 under high CO2 concentration in photobioreactor.

    Science.gov (United States)

    Ge, Yaming; Liu, Junzhi; Tian, Guangming

    2011-01-01

    To understand the potential of cultivating Botryococcus braunii with flue gas (normally containing high CO(2)) for biofuel production, growth characteristics of B. braunii 765 with 2-20% CO(2) aeration were investigated. The results showed that the strain could grow well without any obvious inhibition under all tested CO(2) concentrations with an aeration rate of 0.2 vvm, even without any culture pH adjustment (ranged from 6.0 to 8.0). The maximum biomass among all conditions was 2.31 g L(-1) on 25th day at 20% CO(2). Hydrocarbon content and algal colony size increased with the increase of CO(2) concentration. A negative correlation between algal biomass and culture total phosphorus was observed (from -0.828 to -0.911, P<0.01). Additionally, 2% sodium hypochlorite solution was used for photobioreactor sterilization to cultivate B. braunii. PMID:20584602

  13. Production of highly concentrated, heat stable hepatitis B surface antigen in maize

    Science.gov (United States)

    Hayden, Celine A.; Egelkrout, Erin M.; Moscoso, Alessa M.; Enrique, Cristina; Keener, Todd K.; Jimenez-Flores, Rafael; Wong, Jeffrey C.; Howard, John A.

    2012-01-01

    Summary Plant-based oral vaccines are a promising emergent technology that could help alleviate disease burden worldwide by providing a low-cost, heat stable, oral alternative to parenterally administered commercial vaccines. Here we describe high-level accumulation of the hepatitis B surface antigen (HBsAg) at a mean concentration of 0.51%TSP in maize T1 seeds using an improved version of the globulin1 promoter. This concentration is more than four-fold higher than any previously reported lines. HBsAg expressed in maize seeds was extremely heat stable, tolerating temperatures up to 55°C for one month without degradation. Optimal heat stability was achieved after oil extraction of ground maize material, either by supercritical fluid extraction or hexane treatment. The contributions of this material towards the development of a practical oral vaccine delivery system are discussed. PMID:22816734

  14. Highly efficient production of [18F]fallypride using small amounts of base concentration

    International Nuclear Information System (INIS)

    To minimize the base concentration of a phase-transfer catalyst, [18F]fluoride was extracted from 18O-enriched water trapped on an activated ion exchange cartridge (Chromafix) PS-HCO3) using different concentrations of tetrabutylammonium bicarbonate (TBAHCO3) or Kryptofix 2.2.2./K2CO3 in organic solvents such as CH3CN/H2O or MeOH/H2O. The optimal labeling condition for [18F]fallypride with automated synthesis was that 2 mg of tosyl-fallypride in acetonitrile (1 mL) was heated at 100 oC for 10 min using 40% TBAHCO3 (10 ?L). [18F]Fallypride was obtained with a high radiochemical yield of approximately 68±1.6% (decay-corrected, n=42) with a total synthesis time of 51±1.2 min, including HPLC purification and solid-phase purification for the final formulation.

  15. Solvent extraction of uranium(VI) with benzyloctadecyldimethylammonium chloride (BODMAC) from highly concentrated chloride solution

    International Nuclear Information System (INIS)

    The mechanism of solvent extraction of uranium(VI) from highly concentrated chloride solution with a quaternary ammonium salt, benzyloctadecyldimethylammonium chloride (BODMAC, R4NCl), dissolved in chloroform was studied. The compositions of the extracted species were R4N x UO2Cl3 and (R4N)2 x UO2Cl4. The extraction process is exothermic (?H deg = -8.42±0.54 KJ/mol). Kex1 and Kex2 are calculated to be (3.62±0.55) x 10-2 and (1.06±0.17) x 103, respectively. In the extraction process, a W/O uranium(VI) rich emulsion solution has been formed between the organic and aqueous phases, its volume increased with the increase of BODMAC in the system. The influences of temperature, NaCl, MgCl2 and MgSO4 concentrations on the extraction equilibrium were also studied. (author)

  16. Production of highly concentrated, heat-stable hepatitis B surface antigen in maize.

    Science.gov (United States)

    Hayden, Celine A; Egelkrout, Erin M; Moscoso, Alessa M; Enrique, Cristina; Keener, Todd K; Jimenez-Flores, Rafael; Wong, Jeffrey C; Howard, John A

    2012-10-01

    Plant-based oral vaccines are a promising emergent technology that could help alleviate disease burden worldwide by providing a low-cost, heat-stable, oral alternative to parenterally administered commercial vaccines. Here, we describe high-level accumulation of the hepatitis B surface antigen (HBsAg) at a mean concentration of 0.51%TSP in maize T1 seeds using an improved version of the globulin1 promoter. This concentration is more than fourfold higher than any previously reported lines. HBsAg expressed in maize seeds was extremely heat stable, tolerating temperatures up to 55 °C for 1 month without degradation. Optimal heat stability was achieved after oil extraction of ground maize material, either by supercritical fluid extraction or hexane treatment. The contributions of this material towards the development of a practical oral vaccine delivery system are discussed. PMID:22816734

  17. Active and passive monitoring of benzene in Milan from 1992 up to today

    International Nuclear Information System (INIS)

    The air quality degradation in large urban areas, mainly due to the traffic, is evaluated through the measurement of pollutants coming, directly or indirectly, from the traffic itself. Due to its cancerogenicity, a quality standard for benzene has been settled by D.M.25/11/1994, which obliges this measure in towns having more than 150.000 inhabitants.Starting from 1992, Milan P.M.I.P. has been controlling benzene and other homologues concentrations in air with routine and campaign measurements. Concentrations change depends both on variations of fuel formulation and on the renewal of the cars fleet. As a matter of fact, the lower benzene percentage in fuels and the use of tailpipes with catalytic converter greatly reduced the emission of these compounds in air, giving an estimate annual average lower than the impose limit. In an urban area, an estimate of an average concentration starting from the three sampling points according to the low can give a value far from the real average level; to solve this problem Milan P.M.I.P. programmed an annual campaign with daily sampling in 24 sites homogeneously located in Milan territory

  18. Stable lead isotopes reveal a natural source of high lead concentrations to gasoline-contaminated groundwater

    Science.gov (United States)

    Landmeyer, J.E.; Bradley, P.M.; Bullen, T.D.

    2003-01-01

    Concentrations of total lead as high as 1,600 ??g/L were detected in gasoline-contaminated and uncontaminated groundwater at three gasoline-release sites in South Carolina. Total lead concentrations were highest in turbid groundwater samples from gasoline-contaminated and uncontaminated wells, whereas lower turbidity groundwater samples (collected using low-flow methods) had lower total lead concentrations. Dissolved lead concentrations in all wells sampled, however, were less than 15 ??g total lead/L, the current United States Environmental Protection Agency (US EPA) maximum contaminant level (MCL). Because many total lead concentrations exceeded the MCL, the source of lead to the groundwater system at two of the three sites was investigated using a stable lead isotope ratio approach. Plots of the stable isotope ratios of lead (Pb) in groundwater as 207Pb/206Pb versus 208Pb/206Pb, and 208Pb/204Pb versus 206Pb/204Pb were similar to ratios characteristic of lead-based minerals in local rocks of the southeastern US, and were not similar to the stable lead isotopes ratios characteristic of distant lead ore deposits such as Broken Hill, Australia, used to produce tetraethyl lead in gasoline products prior to its phase-out and ban in the United States. Moreover, the isotopic composition of dissolved lead was equivalent to the isotopic composition of total lead in turbid samples collected from the same well, suggesting that the majority of the lead detected in the groundwater samples was associated with sediment particulates of indigenous aquifer material, rather than lead associated with spilled leaded gasoline. The results of this investigation indicate that (1) lead detected at some gasoline-release sites may be derived from the local aquifer material, rather than the gasoline release, and consequently may affect site-specific remediation goals; (2) non-low flow groundwater sampling methods, such as a disposable bailer, may result in turbid groundwater samples and high total lead concentrations, and; (3) stable lead isotopes can be used to clarify the source of lead detected above permissible levels in gasoline-contaminated groundwater systems.

  19. Mitigation of indoor radon in an area with unusually high radon concentrations.

    Science.gov (United States)

    Ennemoser, O; Oberdorfer, E; Brunner, P; Schneider, P; Purtscheller, F; Stingl, V; Ambach, W

    1995-08-01

    In an area of unusually high indoor radon concentrations of up to 270,000 Bq m-3, four houses were selected for mitigation of indoor radon. Methods used were basement sealing, soil depressurization, a mechanical intake and outlet ventilation system with heat exchanger in the basement, and a multilayer floor construction using a fan to suck radon from a layer between bottom slab and floor. Basement sealing proved unsuccessful, the radon concentration remained unchanged after the mitigation attempt. The most successful remedial measure was soil depressurization using two fans and loops of drainage tubes to withdraw radon from the region under the floor and outside the walls of the basement and from soil under the part of the house without a basement. This method reduced the basement radon level in winter by about a factor of 200, i.e., from 100,000 Bq m-3 to 500 Bq m-3, and the ground-floor level by about a factor of 400. As regards the mechanical intake and outlet ventilation system with heat exchanger in the basement, it is essential to ensure that ventilation provides increased air pressure in the basement compared to outdoors. Unbalanced mechanical intake and outlet ventilation may decrease the air pressure indoors compared to outdoors, leading to increased radon concentrations. Optimization of this method reduced radon concentrations from 200,000 Bq m-3 to 2,000-3,000 Bq m-3 in winter. In one house with only a very small basement, a multilayer floor construction using a fan to suck radon from a layer between the bottom slab and floor was found to reduce radon concentrations on the ground floor from 25,000 Bq m-3 to about 1,700 Bq m-3 in winter. The results show that even in areas with extremely high radon concentrations, effective mitigation of indoor radon can be accomplished if suitable techniques are used. The evaluation of the different mitigation methods shows good coincidence with the ICRP 65 report. PMID:7622369

  20. Large-area, high-intensity PV arrays for systems using dish concentrating optics

    Energy Technology Data Exchange (ETDEWEB)

    Ward, J.S.; Duda, A.; Zweibel, K.; Coutts, T.J. [National Renewable Energy Lab., Golden, CO (United States)

    1998-09-01

    In this paper, the authors report on efforts to fabricate monolithic interconnected modules (MIMs) using III-V semiconductors with bandgaps appropriate for the terrestrial solar spectrum. The small size of the component cells comprising the MIM allows for operation at extremely high flux densities and relaxes the requirement for a small spot size to be generated by the optics. This makes possible a PV option for the large dish concentrator systems that have been developed by the solar thermal community for use with Stirling engines. Additionally, the highly effective back-surface reflector integrated into the MIM design is an effective tool for thermal management of the array. Development of this technology would radically alter the projections for PV manufacturing capacity because of the potential for extremely high power generation per unit area of semiconductor material.

  1. Femtosecond optical Kerr shutter switching in glass containing high concentration of Bi2O3

    Science.gov (United States)

    Sugimoto, Naoki; Ito, Setsuro; Fujiwara, Seiji; Suzuki, Toshio; Kanbara, Hirohisa; Hirao, Kazuyuki

    1998-12-01

    Nonresonant-type Bi2O3-B2O3-SiO2 glass containing high concentration of Bi2O3 was prepared by a melting method. Optical Kerr shutter switching and degenerated four wave mixing experiments for this glass were performed using femtosecond laser. This glass exhibited ultrafast response below 150 femtosecond in optical Kerr switching operation. Moreover, THz optical switching was successfully performed with this glass using 1.5 THz pulse train as the gate beam. Ultrafast response and high threshold for optical damage were also confirmed with this glass at the communication wavelength of 1.5 micrometers . These results indicate that high speed switching beyond THz can be realized using Bi2O3-glass.

  2. Topical capsaicin for pain management: therapeutic potential and mechanisms of action of the new high-concentration capsaicin 8% patch

    OpenAIRE

    Anand, P.; Bley, K.

    2011-01-01

    Topical capsaicin formulations are used for pain management. Safety and modest efficacy of low-concentration capsaicin formulations, which require repeated daily self-administration, are supported by meta-analyses of numerous studies. A high-concentration capsaicin 8% patch (Qutenza™) was recently approved in the EU and USA. A single 60-min application in patients with neuropathic pain produced effective pain relief for up to 12 weeks. Advantages of the high-concentration capsaicin patch in...

  3. Modified water solubility of milk protein concentrate powders through the application of static high pressure treatment.

    Science.gov (United States)

    Udabage, Punsandani; Puvanenthiran, Amirtha; Yoo, Jin Ah; Versteeg, Cornelis; Augustin, Mary Ann

    2012-02-01

    The effects of high pressure (HP) treatment (100-400 MPa at 10-60 °C) on the solubility of milk protein concentrate (MPC) powders were tested. The solubility, measured at 20 °C, of fresh MPC powders made with no HP treatment was 66%. It decreased by 10% when stored for 6 weeks at ambient temperature (~20 °C) and continued to decrease to less than 50% of its initial solubility after 12 months of storage. Of the combinations of pressure and heat used, a pressure of 200 MPa at 40 °C applied to the concentrate before spray drying was found to be the most beneficial for improved solubility of MPC powders. This combination of pressure/heat improved the initial cold water solubility to 85%. The solubility was maintained at this level after 6 weeks storage at ambient temperature and 85% of the initial solubility was preserved after 12 months. The improved solubility of MPC powders on manufacture and on storage are attributed to an altered surface composition arising from an increased concentration of non-micellar casein in the milk due to HP treatment prior to drying. The improved solubility of high protein powders (95% protein) made from blends of sodium caseinate and whey protein isolate compared with MPC powders (~85% protein) made from ultrafiltered/diafiltered milk confirmed the detrimental role of micellar casein on solubility. The results suggest that increasing the non-micellar casein content by HP treatment of milk or use of blends of sodium caseinate and whey proteins are strategies that may be used to obtain high protein milk powders with enhanced solubility. PMID:22127220

  4. Synergistic extraction of cobalt(II) with oxine/decanoic acid solution mixtures in benzene and chloroform

    International Nuclear Information System (INIS)

    Synergistic extraction of Co(II) with 8-hydroxyquinoline (Hq)/decanoic acid [(HR)2] solution mixtures in benzene and chloroform was carried out at 25 deg C. The aqueous ionic strength and the total concentration of cobalt(II) were 0.1 (NaCl) and 1 x 10-5 -1 x 10-3M, respectively. The synergistic effect is interpreted by the formation of the mixed ligand ion-pair complexes: [(Coq(Hq)2(HR))+, R-] and [(Coq(Hq)2(HR)3)+, R-] in benzene and chloroform, respectively. (author). 36 refs., 6 figs

  5. A Universal Intrinsic Scale of Hole Concentration for High-Tc Cuprates

    CERN Document Server

    Honma, T; Hsieh, H H; Tanimoto, M

    2003-01-01

    We have measured room-temperature thermoelectric power (S290) as a function of hole concentration per planer Cu atom (Ppl) in Y1-xCaxBa2Cu3O6(0.05high temperature superconductors, Tc depends on the inter-layer couplings.

  6. High concentrations of KCl release noradrenaline from noradrenergic neurons in the rat anococcygeus muscle

    Scientific Electronic Library Online (English)

    C.B.L., Araujo; L.M., Bendhack.

    2003-01-01

    Full Text Available The aim of the present study was to investigate the effects of high concentrations of KCl in releasing noradrenaline from sympathetic nerves and its actions on postsynaptic alpha-adrenoceptors. We measured the isotonic contractions induced by KCl in the isolated rat anococcygeus muscle under differe [...] nt experimental conditions. The contractile responses induced by KCl were inhibited by alpha-adrenoceptor antagonists in 2.5 mM Ca2+ solution. Prazosin reduced the maximum effect from 100 to 53.9 ± 10.2% (P

  7. Thin films of Pd/Ni alloys for detection of high hydrogen concentrations

    Science.gov (United States)

    Hughes, R. C.; Schubert, W. K.

    1992-01-01

    Thin alloy films of Pd and Ni formed by dual-electron-beam evaporation techniques have been found to give durable and quickly reversible detectors of high H2 concentrations near 1 atm and 300 K, including accurate determinations of pH2 around the lower explosive limit of 4 percent in air. The addition of Ni suppresses the alpha to beta phase transition found in pure Pd under these conditions. The measurement of resistivity changes in the thin films along with flatbands shifts of metal-oxide-semiconductor capacitors on the same Si wafer gives accurate values of pH2 over more than six decades.

  8. Triple-Junction Solar Cells for Ultra-High Concentrator Applications

    OpenAIRE

    Barrigón Montañés, Enrique; Garcia Tabares Valdivieso, Elisa; García Vara, Iván; Rey-Stolle Prado, Ignacio; Algora del Valle, Carlos

    2011-01-01

    After the successful implementation of a record performing dual-junction solar cell at ultra high concentration, in this paper we present the transition to a triple-junction device. The semiconductor structure of the solar cells is presented and the main changes in respect to a dual-junction design are briefly discussed. Cross-sectional TEM analysis of samples confirms that the quality of the triple-junction structures grown by MOVPE is good, revealing no trace of antiphase disorder, and show...

  9. Reduction of Uranium(VI) to Uranium (IV) by Three Facultative Anaerobes at High Concentrations

    Science.gov (United States)

    Chabalala, Simphiwe; Chirwa, Evans M. N.

    2010-01-01

    Six bacteria species were isolated from a uranium mine in Limpopo, South Africa, and three facultative anaerobes reduced U(VI) to U(IV) and aided the removal of U(VI) from solution. The pure cultures showed a high reduction rate at pH 5 to 6 for concentrations 100-800 mg/L during the first 4 to 6 hours of incubation. A biological remediation process for removing U(VI) is desirable in the nuclear industry where more expensive environmentally non-friendly physical chemical processes have been used conventionally for decades.

  10. Levonorgestrel, medroxyprogesterone and progesterone cause a concentration-dependent reduction in endometrial cancer (Ishikawa) cell density, and high concentrations of progesterone and mifepristone act in synergy.

    Science.gov (United States)

    Moe, Bjørn T; Vereide, Anne B; Orbo, Anne; Jaeger, Ragnhild; Sager, Georg

    2009-04-01

    Endometrial hyperplasia is a precursor lesion of endometrial carcinoma. Clinical studies of endometrial hyperplasia have shown that levonorgestrel (LNG) is more therapeutically effective than medroxyprogesterone acetate (MPA). The present pharmacological in vitro study was performed to compare progestin effects on human endometrial cancer (Ishikawa) cells. Supraphysiological concentrations of progesterone (PG) and high concentrations of LNG and MPA were employed to determine the order of potency in reducing cell density. The order of potency was LNG>MPA>PG with respective 50% inhibitory concentrations (IC(50)) of 3.9+/-0.4, 30.4+/-3.4 and 45.3+/-2.7 microM. Mifepristone (MF) is a potent antiprogestin, but was unable to antagonize the PG-induced cell density reduction. For MF concentrations from 0.2 to 70 microM alone, a PG-mimetic effect was observed with an IC(50) value of 19.0+/-1.7 muM. When PG and MF were combined, a marked reinforcement of the effect was seen. These observations indicate that extranuclear initiated signaling pathways are involved in the reduction of endometrial cancer cells exposed to high concentrations of PG and MF. PMID:19414344

  11. High resolution 4-D spectroscopy with sparse concentric shell sampling and FFT-CLEAN

    International Nuclear Information System (INIS)

    Recent efforts to reduce the measurement time for multidimensional NMR experiments have fostered the development of a variety of new procedures for sampling and data processing. We recently described concentric ring sampling for 3-D NMR experiments, which is superior to radial sampling as input for processing by a multidimensional discrete Fourier transform. Here, we report the extension of this approach to 4-D spectroscopy as Randomized Concentric Shell Sampling (RCSS), where sampling points for the indirect dimensions are positioned on concentric shells, and where random rotations in the angular space are used to avoid coherent artifacts. With simulations, we show that RCSS produces a very low level of artifacts, even with a very limited number of sampling points. The RCSS sampling patterns can be adapted to fine rectangular grids to permit use of the Fast Fourier Transform in data processing, without an apparent increase in the artifact level. These artifacts can be further reduced to the noise level using the iterative CLEAN algorithm developed in radioastronomy. We demonstrate these methods on the high resolution 4-D HCCH-TOCSY spectrum of protein G's B1 domain, using only 1.2% of the sampling that would be needed conventionally for this resolution. The use of a multidimensional FFT instead of the slow DFT for initial data processing and for subsequent CLEAN significantly reduces the calculation time, yielding an artifact level that is on par with the level of th level that is on par with the level of the true spectral noise

  12. Synchronous phase-demodulation of high spatial frequency, concentric-rings, Placido fringe patterns

    CERN Document Server

    Servin, Manuel

    2012-01-01

    Here a synchronous phase-demodulation method for high spatial frequency (HSF), concentric-rings Placido fringe pattern is proposed. The earliest use of this concentric-rings pattern was to gauge non-spherical irregularities of the human cornea by Portuguese ophthalmologist Antonio Placido in 1880. Most modern corneal topographers use Placido patterns to test human cornea irregularities; a field of application of this paper. Another field of application of HSF conic-carrier fringe patterns is to test wavefronts using what may be called the Placido-Hartmann screen test. These screens would be formed by periodic concentric ring apertures. A Placido-Hartmann test would be sensitive to the radial slope of the wavefront under measurement. Finally as in the Hartmann-Shack test, one may use a radial lenslet array of toroidal-shaped lenses to test the radial slope of a wavefront at the focal plane. The main advantage of estimating the radial slope of a wavefront using a HSF Placido pattern is that a single radial slop...

  13. High plasma concentrations of asymmetric dimethylarginine inhibit ischemic cardioprotection in hypercholesterolemic rats

    Scientific Electronic Library Online (English)

    M.B.P., Landim; P.M.M., Dourado; A., Casella-Filho; A.C.P., Chagas; P.L., da-Luz.

    2013-05-10

    Full Text Available A low concentration of nitric oxide associated with a high concentration of asymmetric dimethylarginine (ADMA) can explain the lack of ischemic cardioprotection observed in the presence of hypercholesterolemia. The objective of the present study was to evaluate the effect of hypercholesterolemia on [...] ischemic pre- and postconditioning and its correlation with plasma concentrations of ADMA. Male Wistar rats (6-8 weeks old) fed a 2% cholesterol diet (n = 21) for 8 weeks were compared to controls (n = 25) and were subjected to experimental myocardial infarction and reperfusion, with ischemic pre- and postconditioning. Total cholesterol and ADMA were measured in plasma before the experimental infarct and the infarct area was quantified. Weight, total cholesterol and plasma ADMA (means ± SE; 1.20 ± 0.06, 1.27 ± 0.08 and 1.20 ± 0.08 vs 0.97 ± 0.04, 0.93 ± 0.05 and 0.97 ± 0.04?µM) were higher in animals on the hypercholesterolemic diet than in controls, respectively. Cardioprotection did not reduce infarct size in the hypercholesterolemic animals (pre: 13.55% and post: 8% compared to 7.95% observed in the group subjected only to ischemia and reperfusion), whereas infarct size was reduced in the animals on a normocholesterolemic diet (pre: 8.25% and post: 6.10% compared to 12.31%). Hypercholesterolemia elevated ADMA and eliminated the cardioprotective effects of ischemic pre- and postconditioning in rats.

  14. Picosecond Pulse Radiolysis of Highly Concentrated Phosphoric Acid Solutions: Mechanism of Phosphate Radical Formation.

    Science.gov (United States)

    Ma, Jun; Schmidhammer, Uli; Mostafavi, Mehran

    2015-06-18

    Eight solutions containing phosphoric acid with concentrations ranging from 2 mol L(-1) to neat acid have been studied by picosecond pulse radiolysis. The absorbance of the secondary radical H2PO4(•) formed within 7 ps of the electron pulse is observed using pulse-probe method in the visible. Kinetic analysis shows that the radicals of phosphoric acid are formed via two mechanisms: direct electron detachment and oxidation by the radical cation of water, H2O(•+). On the basis of molar extinction coefficient value of 1850 L mol(-1) cm(-1), at 15 ps the radiolytic yield of H2PO4(•) formation by direct energy absorption is 3.7 ± 0.1 × 10(-7) mol J(-1) in neat phosphoric acid. In highly concentrated phosphoric acid solutions, the total yield of phosphate radical at 15 ps exhibits an additional contribution that can be explained by electron transfer from phosphoric acid to H2O(•+). The efficiency of the electron transfer to this strongly oxidizing species in phosphoric acid solutions is lower compared with the one in sulfuric acid solutions. Two explanations are given to account for a relatively low efficiency of H2O(•+) scavenging in concentrated phosphoric acid solutions. PMID:25176139

  15. High concentration in-diffusion of phosphorus in Si from a spray-on source

    International Nuclear Information System (INIS)

    High concentration in-diffusion of phosphorus in both Czochralski grown and solar grade multicrystalline Si from a spray-on liquid source has been studied by secondary ion mass spectrometry and electrochemical capacitance-voltage profiling. By extraction of the concentration dependent effective diffusivity employing the Boltzmann-Matano analysis, we adapt an integrated diffusion model based on a previous work by Uematsu [J. Appl. Phys. 82, 2228 (1997)], in order to gain insight into the mechanisms governing such in-diffusions. We find that in the tail region of the profiles, diffusion is mediated by interaction with Si self-interstitials, whereas a vacancy mechanism via doubly negative vacancies dominates in the higher concentration region towards the surface, in correspondence with a previous analysis by Fair and Tsai [J. Electrochem. Soc. 124, 1107 (1977)]. Moreover, we find that both the vacancy and interstitial mechanisms can be described by an Arrhenius behavior, exhibiting apparent activation energies of 5.2±0.3 and 2.1±0.1 eV, respectively. The results form the basis for a simplified diffusion simulation, allowing simulation and subsequent optimization of phosphorus diffused emitters commonly employed in Si solar cells

  16. Indoor radon (Rn-222) concentration measurements in Cyprus using high-sensitivity portable detectors

    CERN Document Server

    Anastasiou, T; Christofides, S; Christodoulides, G

    2003-01-01

    Using high--sensitivity radon (Rn-222) portable detectors, the airborne Rn-222 concentration in the interior of various Cypriot buildings and dwellings was measured. For each preselected building and dwelling, a calibrated detector was put into a closed room, and the Rn-222 concentration was registered in sampling intervals of 2 to 4 hours for a total counting time of typically 48 hours. Rn-222 activity concentrations were found to be in the range of 6.2 to 102.8 Bq/m**3, with an overall arithmetic mean value of (19.3 +- 1.6) Bq/m**3. This value is by a factor of two below the world average (population-weighted) value of 39 Bq/m**3. The total annual effective dose equivalent to the Cypriot population was calculated to be between 0.16 and 2.6 mSv with an overall arithmetic mean value of (0.49 +- 0.04) mSv.

  17. Subcutaneous absorption kinetics of two highly concentrated preparations of recombinant human growth hormone.

    DEFF Research Database (Denmark)

    Laursen, Torben; JØrgensen, Jens Otto Lunde

    1993-01-01

    Abstract OBJECTIVE: The relative bioavailability of two highly concentrated (12 IU/ml) formulations of biosynthetic human growth hormone (GH) administered subcutaneously was compared. DESIGN: A randomized, crossover study. Conventional GH therapy was withdrawn 72 hours before each study period. There was a washout period of at least four weeks between the study periods. SETTING: Participants were recruited from an outpatient clinic and were hospitalized during the two study periods. PATIENTS: Fourteen GH-deficient patients (mean age 25.2 y, range 14-54). One patient was excluded from data analysis because of signs of endogenous GH secretion. INTERVENTIONS: At the start of each study period, GH 3 IU/m2 was injected subcutaneously. The two formulations, PenFill and PenSet, differ in the buffers used and in the relative content of mannitol and glycine. Serum profiles of GH were monitored frequently for 24 hours. Samples were taken every 30 minutes for 6 hours and then hourly. MAIN OUTCOME MEASURES: Bioavailability (F) and absorption dynamics of human GH were measured. The relative absorption fractions estimated from the areas under the individual serum concentration curves from 0 to 24 hours, and the observed time (Tmax) to reach the maximum concentration (Cmax) were determined. Short-term metabolic effects of GH on insulin-like growth factor (IGF-I), glucose, and insulin were determined. RESULTS: The geometric mean (SD) of F was 0.910 (1,236). The 90 percent confidence interval was 0.819-1.010. Mean (+/- SD) of Cmax was 12.65 +/- 5.89 and 12.58 +/- 4.40 ng/mL for PenFill and PenSet, respectively. Corresponding values for Tmax were 5.49 +/- 1.55 and 5.89 +/- 1.79 hours for PenFill and PenSet, respectively. There was a considerable interindividual variation, but the relative absorption fraction did not significantly differ from 1 (p = 0.13). Neither Cmax (p = 0.74) nor Tmax (p = 0.58) of the two formulations was significantly different. Injection of the two formulations induced similar increments in serum IFG-I (p = 0.48). Serum insulin and blood glucose concentrations were not significantly different. CONCLUSIONS: There is no significant difference between the absorption kinetics and short-term metabolic effects of these two highly concentrated formulations of biosynthetic GH. The two formulations are bioequivalent.

  18. 40 CFR 721.9595 - Alkyl benzene sulfonic acids and alkyl sulfates, amine salts (generic).

    Science.gov (United States)

    2010-07-01

    ...2010-07-01 false Alkyl benzene sulfonic acids and alkyl sulfates, amine salts... § 721.9595 Alkyl benzene sulfonic acids and alkyl sulfates, amine salts...identified generically as alkyl benzene sulfonic acids and alkyl sulfates,...

  19. Benzene synthesis using aluminosilicate catalysts for determining 14C activity by liquid scintillation method

    International Nuclear Information System (INIS)

    The basic characteristics are described of various aluminosilicate catalysts used for benzene synthesis. The methods of catalyst preparation and the methodology of benzene synthesis guaranteeing a 98% benzene yield are described. (author)

  20. 76 FR 52875 - 2-Propenoic Acid, Polymer With Ethenylbenzene and (1-methylethenyl) Benzene, Sodium Salt...

    Science.gov (United States)

    2011-08-24

    ...1- methylethenyl) Benzene, Sodium Salt; Tolerance Exemption AGENCY: Environmental...1-methylethenyl) benzene, sodium salt when used as an inert ingredient in a pesticide...1- methylethenyl) benzene, sodium salt on food or feed commodities. DATES:...

  1. 40 CFR 721.1580 - Disubstituted benzene ether, polymer with substituted phenol (generic).

    Science.gov (United States)

    2010-07-01

    ...benzene ether, polymer with substituted phenol (generic). 721.1580 Section 721...benzene ether, polymer with substituted phenol (generic). (a) Chemical substance...benzene ether, polymer with substituted phenol (PMN P-98-155) is subject to...

  2. Simultaneous determination of multiple marker constituents in concentrated Gegen Tang granule by high performance liquid chromatography

    Directory of Open Access Journals (Sweden)

    Yip Yuekeung

    2007-06-01

    Full Text Available Abstract Background Concentrated Gegen Tang (GT granule is a widely available traditional Chinese medicinal product for the treatment of cold and flu. There was no reliable analytical method available for the quality assessment of GT granules. Methods An HPLC method with an Agilent Zorbax SB-Phenyl Stablebond column (250 × 4.6 mm, 5 ?m was developed and validated. The mobile phase gradient was a mixture of 0.1% trifluoroacetic acid (TFA in acetonitrile (ACN and 0.1% TFA in water. The detection with a diode-array detector was set at 207, 230, 250 and 275 nm. Seven components, namely puerarin, daidzein, paeoniflorin, cinnamic acid, glycyrrhizin, ephedrine and pseudoephedrine were selected as marker compounds for the evaluation. Results The regression equations revealed good linear relationships (correlation coefficients: 0.9994–0.9998 between the peak areas and concentrations. The recovery was between 98.8% and 101.7% with good precision and accuracy. The quality of GT granule from four different manufacturers was evaluated with this newly developed method. Samples from four manufacturers showed similar profiles but contents of the detected markers varied significantly among manufacturers and batches. Conclusion A new method using high performance liquid chromatography (HPLC has been developed for simple and reliable quality control of commercial concentrated GT granules. Sensitivity was increased by multi-wavelength detection. The contents of selected marker components in GT granules varied significantly among manufacturers and batches, making it necessary to evaluate the quality of concentrated GT granules in the market.

  3. Effects of Relative Humidity on Ozone and Secondary Organic Aerosol Formation from the Photooxidation of Benzene and Ethylbenzene

    Science.gov (United States)

    Jia, L.; Xu, Y.

    2012-12-01

    The formation of ozone and secondary organic aerosol from benzene-NOx and ethylbenzene-NOx irradiations was investigated under different levels of relative humidity (RH) in a smog chamber. The results show that the increase in RH can greatly reduce the maximum O3 by the transformation of -NO2 and -ONO2-containing products into the particle phase. In benzene irradiations, the SOA number concentration increases over 26 times as RH rises from ethylbenzene irradiations, ethylglyoxal favors the formation of monohydrate, which limits the RH effects. During evaporating processes, the lost substances have similar structures for both benzene and ethylbenzene. This demonstrates that ethyl-containing substances are very stable and difficult to evaporate. For benzene some of glyoxal hydrates are left to form C-O-C and C=O-containing species like hemiacetal and acetal after evaporation, whereas for ethylbenzene, glyoxal favors cross reactions with ethylglyoxal during the evaporating process. It is concluded that the increase in RH can irreversibly enhance the yields of SOA from both benzene and ethylbenzene.

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

    Directory of Open Access Journals (Sweden)

    Kheirbek Iyad

    2012-07-01

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

  5. FBAR syndapin 1 recognizes and stabilizes highly curved tubular membranes in a concentration dependent manner

    DEFF Research Database (Denmark)

    Ramesh, Pradeep; Baroji, Younes F.

    2013-01-01

    Syndapin 1 FBAR, a member of the Bin-amphiphysin-Rvs (BAR) domain protein family, is known to induce membrane curvature and is an essential component in biological processes like endocytosis and formation and growth of neurites. We quantify the curvature sensing of FBAR on reconstituted porcine brain lipid vesicles and show that it senses membrane curvature at low density whereas it induces and reinforces tube stiffness at higher density. FBAR strongly up-concentrates on the high curvature tubes pulled out of Giant Unilamellar lipid Vesicles (GUVs), this sorting behavior is strongly amplified at low protein densities. Interestingly, FBAR from syndapin 1 has a large affinity for tubular membranes with curvatures larger than its own intrinsic concave curvature. Finally, we studied the effect of FBAR on membrane relaxation kinetics with high temporal resolution and found that the protein increases relaxation time of the tube holding force in a density-dependent fashion.

  6. Adaptation to high salt concentrations in halotolerant/ halophilic fungi: a molecular perspective

    Directory of Open Access Journals (Sweden)

    AnaPlemenitas

    2014-05-01

    Full Text Available Molecular studies of salt tolerance of eukaryotic microorganisms have until recently been limited to the baker’s yeast Saccharomyces cerevisiae and a few other moderately halotolerant yeast. Discovery of the extremely halotolerant and adaptable fungus Hortaea werneckii and the obligate halophile Wallemia ichthyophaga introduced two new model organisms into studies on the mechanisms of salt tolerance in eukaryotes. H. werneckii is unique in its adaptability to fluctuations in salt concentrations, as it can grow without NaCl as well as in the presence of up to 5 M NaCl. On the other hand, W. ichthyophaga requires at least 1.5 M NaCl for growth, but also grows in up to 5 M NaCl. Our studies have revealed the novel and intricate molecular mechanisms used by these fungi to combat high salt concentrations, which differ in many aspects between the extremely halotolerant H. werneckii and the halophilic W. ichthyophaga. Specifically, the high osmolarity glycerol signalling pathway that is important for sensing and responding to increased salt concentrations is here compared between H. werneckii and W. ichthyophaga. In both of these fungi, the key signalling components are conserved, but there are structural and regulation differences between these pathways in H. werneckii and W. ichthyophaga. We also address differences that have been revealed from analysis of their newly sequenced genomes. The most striking characteristics associated with H. werneckii are the large genetic redundancy, the expansion of genes encoding metal cation transporters, and a relatively recent whole genome duplication. In contrast, the genome of W. ichthyophaga is very compact, as only 4,884 protein-coding genes are predicted, which cover almost three quarters of the sequence. Importantly, there has been a significant increase in their hydrophobins, cell-wall proteins that have multiple cellular functions.

  7. Adaptation to high salt concentrations in halotolerant/halophilic fungi: a molecular perspective.

    Science.gov (United States)

    Plemenitaš, Ana; Lenassi, Metka; Konte, Tilen; Kejžar, Anja; Zajc, Janja; Gostin?ar, Cene; Gunde-Cimerman, Nina

    2014-01-01

    Molecular studies of salt tolerance of eukaryotic microorganisms have until recently been limited to the baker's yeast Saccharomyces cerevisiae and a few other moderately halotolerant yeast. Discovery of the extremely halotolerant and adaptable fungus Hortaea werneckii and the obligate halophile Wallemia ichthyophaga introduced two new model organisms into studies on the mechanisms of salt tolerance in eukaryotes. H. werneckii is unique in its adaptability to fluctuations in salt concentrations, as it can grow without NaCl as well as in the presence of up to 5 M NaCl. On the other hand, W. ichthyophaga requires at least 1.5 M NaCl for growth, but also grows in up to 5 M NaCl. Our studies have revealed the novel and intricate molecular mechanisms used by these fungi to combat high salt concentrations, which differ in many aspects between the extremely halotolerant H. werneckii and the halophilic W. ichthyophaga. Specifically, the high osmolarity glycerol signaling pathway that is important for sensing and responding to increased salt concentrations is here compared between H. werneckii and W. ichthyophaga. In both of these fungi, the key signaling components are conserved, but there are structural and regulation differences between these pathways in H. werneckii and W. ichthyophaga. We also address differences that have been revealed from analysis of their newly sequenced genomes. The most striking characteristics associated with H. werneckii are the large genetic redundancy, the expansion of genes encoding metal cation transporters, and a relatively recent whole genome duplication. In contrast, the genome of W. ichthyophaga is very compact, as only 4884 protein-coding genes are predicted, which cover almost three quarters of the sequence. Importantly, there has been a significant increase in their hydrophobins, cell-wall proteins that have multiple cellular functions. PMID:24860557

  8. Investigation of benzene and toluene layers on 0001 surface of graphite by means of neutron scattering

    International Nuclear Information System (INIS)

    The structures of benzene (C6H6, C6D6) and toluene (C6H5-CH3, C6D5-CD3) monolayers on the basal planes of graphite have been investigated by neutron diffraction. The dynamics of the benzene layer has been studied by observing the incoherently, inelastically scattered neutrons using the time-of-flight method. The main results are: Above a phase transition temperature Tsub(c)approx.=145 K benzene on the basal planes of graphite forms a quasi 2D-fluid with high compressibility. For toluene a fluid phase exists above 140 K, between 70 K and 140 K it forms an incommensurate layer and below 70 K a 3x3 structure has been observed. The fluid phase of adsorbed benzene shows a broad quasielastic scattering indicating an effective surface diffusion coefficient of 10-4 cm2/s at 200 K. The inelastic spectrum has been compared with an appropriate lattice dynamical model. The comparison with the data reveals, can be considered as a fairly anharmonic 2D-solid with a static external potential due to the substrate. (orig./HK)

  9. Carbon-carbon bond cleavage and rearrangement of benzene by a trinuclear titanium hydride

    Science.gov (United States)

    Hu, Shaowei; Shima, Takanori; Hou, Zhaomin

    2014-08-01

    The cleavage of carbon-carbon (C-C) bonds by transition metals is of great interest, especially as this transformation can be used to produce fuels and other industrially important chemicals from natural resources such as petroleum and biomass. Carbon-carbon bonds are quite stable and are consequently unreactive under many reaction conditions. In the industrial naphtha hydrocracking process, the aromatic carbon skeleton of benzene can be transformed to methylcyclopentane and acyclic saturated hydrocarbons through C-C bond cleavage and rearrangement on the surfaces of solid catalysts. However, these chemical transformations usually require high temperatures and are fairly non-selective. Microorganisms can degrade aromatic compounds under ambient conditions, but the mechanistic details are not known and are difficult to mimic. Several transition metal complexes have been reported to cleave C-C bonds in a selective fashion in special circumstances, such as relief of ring strain, formation of an aromatic system, chelation-assisted cyclometallation and ?-carbon elimination. However, the cleavage of benzene by a transition metal complex has not been reported. Here we report the C-C bond cleavage and rearrangement of benzene by a trinuclear titanium polyhydride complex. The benzene ring is transformed sequentially to a methylcyclopentenyl and a 2-methylpentenyl species through the cleavage of the aromatic carbon skeleton at the multi-titanium sites. Our results suggest that multinuclear titanium hydrides could serve as a unique platform for the activation of aromatic molecules, and may facilitate the design of new catalysts for the transformation of inactive aromatics.

  10. Retrieving TN and TP Concentration of Urban River From High Resolution IKONOS Multispectral Imagery

    Science.gov (United States)

    Zhang, Y.; Liu, J.; Zhang, L.; Song, X.

    2014-12-01

    Total nitrogen (TN) and Total phosphorus (TP) are widely known as two important indexes to measure China urban rivers, and the technique of remote sensing plays an important role in quantitatively monitoring the dynamic change and timely grasping the status of urban rivers. Taking Wen-rui Tang River as examples, this paper develops both multiple regressions (MR) model and artificial neural networks (ANN) model to estimate TN and TP concentration from high resolution IKONOS image data and in situ water samples collected concurrently with satellite overpass. By analyzing determination coefficients (R2) and relative root mean square error (RMSE), it is found that the measured and estimated values of both MR and ANN models are in good agreement (R2>0.85 and RMSE0.86 and RMSE<0.89). The results also present the potential of high resolution IKONOS multispectral imagery to apply to urban rivers. The spatial distribution maps of TP and TN concentration generated by ANN model present apparent spatial variations and inform the decision makers of water quality variations in Wen-rui Tang River. The approach developed in this study proves to be effective and has the potential to be applied over urban rivers for water quality monitoring.

  11. Correlation between collimated flash test and in-sun measurements of high concentration photovoltaic modules

    Science.gov (United States)

    Green, Evan; Taylor, Sean; Cowley, Sam; Luo, Xin

    2009-08-01

    Due to their limited angular acceptance, and use of spectrally sensitive multi-junction solar cells, high concentration photovoltaic modules represent a challenging measurement task. In collaboration with Instituto de Energia Solar at the Universidad Politecnica de Madrid, SolFocus has designed and manufactured an industrialized solar simulator for characterization of high concentration photovoltaic modules. The simulator measures module peak conversion efficiency and acceptance angle. The simulator uses a Xenon flash source with collimating optics to form a uniform one-sun illumination covering sufficient area to measure two panels of 1 m2 each, along with reference measurement cells for spectral and power normalization. The on-sun measurement uses a normal incidence pyrheliometer and temperature sensors to provide normalization information. This paper presents an algorithm for normalization of tests performed under factory conditions to IEC 62108 standard operating conditions (850 W/m2 direct-normal-irradiance, 20 C ambient temperature). After normalization, tested panels are correlated to actual on-sun performance measurements. We present descriptions of the normalizations applied to both the factory test method and on-sun test method, and compare the results for a population of over 100 modules. As a result of normalization and correlation methods, we conclude that the simulator predicts on-sun performance to better than +/-10%, with 99% confidence. The primary source of uncertainty is the normalization of the on-sun data. The repeatability of the flash test is better than +/-2%.

  12. High-temperature photochemical destruction of toxic organic wastes using concentrated solar radiation

    Energy Technology Data Exchange (ETDEWEB)

    Dellinger, B.; Graham, J.L.; Berman, J.M.; Taylor, P.H. [Dayton Univ., OH (United States)

    1994-05-01

    Application of concentrated solar energy has been proposed to be a viable waste disposal option. Specifically, this concept of solar induced high-temperature photochemistry is based on the synergistic contribution of concentrated infrared (IR) radiation, which acts as an intense heating source, and near ultraviolet and visible (UV-VIS) radiation, which can induce destructive photochemical processes. Some significant advances have been made in the theoretical framework of high-temperature photochemical processes (Section 2) and development of experimental techniques for their study (Section 3). Basic thermal/photolytic studies have addressed the effect of temperature on the photochemical destruction of pure compounds (Section 4). Detailed studies of the destruction of reaction by-products have been conducted on selected waste molecules (Section 5). Some very limited results are available on the destruction of mixtures (Section 6). Fundamental spectroscopic studies have been recently initiated (Section 7). The results to date have been used to conduct some relatively simple scale-up studies of the solar detoxification process. More recent work has focused on destruction of compounds that do not directly absorb solar radiation. Research efforts have focused on homogeneous as well as heterogeneous methods of initiating destructive reaction pathways (Section 9). Although many conclusions at this point must be considered tentative due to lack of basic research, a clearer picture of the overall process is emerging (Section 10). However, much research remains to be performed and most follow several veins, including photochemical, spectroscopic, combustion kinetic, and engineering scale-up (Section 11).

  13. High concentrations of divalent cations isolate monosynaptic inputs from local circuits in the auditory midbrain

    Directory of Open Access Journals (Sweden)

    ShobhanaSivaramakrishnan

    2013-10-01

    Full Text Available Hierarchical processing of sensory information occurs at multiple levels between the peripheral and central pathway. Different extents of convergence and divergence in top down and bottom up projections makes it difficult to separate the various components activated by a sensory input. In particular, hierarchical processing at sub-cortical levels is little understood. Here we have developed a method to isolate extrinsic inputs to the inferior colliculus (IC, a nucleus in the midbrain region of the auditory system, with extensive ascending and descending convergence. By applying a high concentration of divalent cations (HiDi locally within the IC, we isolate a HiDi-sensitive from a HiDi-insensitive component of responses evoked by afferent input in brain slices and in vivo during a sound stimulus. Our results suggest that the HiDi sensitive component is a monosynaptic input to the IC, while the HiDi-insensitive component is a local polysynaptic circuit. Monosynaptic inputs have short latencies, rapid rise times and underlie first spike latencies. Local inputs have variable delays and evoke long-lasting excitation. In vivo, local circuits have variable onset times and temporal profiles. Our results suggest that high concentrations of divalent cations should prove to be a widely useful method of isolating extrinsic monosynaptic inputs from local circuits in vivo.

  14. Microstructural Properties of High Level Waste Concentrates and Gels with Raman And Infrared Spectroscopies

    International Nuclear Information System (INIS)

    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 water, sodium hydroxide, and sodium salts of nitrate, nitrite, aluminate, carbonate, phosphate, and sulfate. In addition, there are varying amounts of assorted organic salts such as EDTA, glycolate, and citrate. Although measurements of the bulk properties of these wastes (e.g. viscosity, gel point, density) have been reported, little is known about how the macroscopic characteristics are related to the microscopic physico-chemical properties. Viscosity, solids volume percent, and gas retention can dramatically change with relatively small changes in composition and temperature. Furthermore, these same properties are important in determining safe storage conditions as well as in planning retrieval, pretreatment, and disposal of the wastes. The focus of this effort will be on aluminate chemistry since large inventories of waste with aluminum are located at Hanford and Savannah River and little is known about the microstructure of these complex mixtures

  15. Low temperature tensile properties of steels containing high concentrations of helium

    International Nuclear Information System (INIS)

    Due to the high particle energies, the radiation conditions in spallation targets are characterized by very high helium production rates. We simulated this fast helium generation by implantation of ?-particles into AISI 316L and DIN 1.4914 specimens and studied its effect on the mechanical properties by subsequent tensile tests at 25 and 300 deg. C, respectively. Up to He-concentrations of 0.5 at.% the observed hardening and embrittlement can be attributed to displacement-induced defects. However, at around 1 at.% He, the observed increase in yield stress and decrease in ductility are considerably outside the trend lines for the dpa dependence. Such a 'critical' He-concentration was also inferred from hardness measurements on dual-beam irradiated specimens.The microstructure of the implanted specimens shows the usual features appearing in steels after low temperature irradiation ('black dot' damage and dislocation loops). No visible (>1 nm) bubbles could be detected in the specimens, including those containing 1 at.% He

  16. Combined use of ionophore and virginiamycin for finishing Nellore steers fed high concentrate diets

    Scientific Electronic Library Online (English)

    Amoracyr José Costa, Nuñez; Mariana, Caetano; Alexandre, Berndt; João José Assumpção de Abreu, Demarchi; Paulo Roberto, Leme; Dante Pazzanese Duarte, Lanna.

    2013-08-01

    Full Text Available Zebu cattle fed high concentrate diets may present inconsistent performance due to the occurrence of metabolic disorders, like acidosis. The isolated use of ionophores and virginiamycin in high grain diets can improve animal performance and reduce the incidence of such disorders, but recent studies [...] suggested that their combination may have an additive effect. Thus, 72 Nellore steers, 389 ± 15 kg initial body weight (BW), were confined and fed for 79 days to evaluate the combination of virginiamycin and salinomycin on performance and carcass traits. Animals were allocated to a randomized complete block design by BW, in a 2 × 2 factorial arrangement of treatments, with two concentrate levels (73 and 91 %) and two virginiamycin levels (0 and 15 mg kg-1), and salinomycin (13 mg kg-1) included in all diets. The interaction was not significant (p > 0.05). Dry matter intake (DMI), average daily gain (ADG), gain-to-feed ratio (G:F), starch consumed, and fecal starch content were higher (p 0.05) between treatments. Starch consumed and estimated dietary net energy for maintenance (NEm) and gain (NEg) were higher (p

  17. High-speed roll-to-roll manufacturing of graphene using a concentric tube CVD reactor.

    Science.gov (United States)

    Polsen, Erik S; McNerny, Daniel Q; Viswanath, B; Pattinson, Sebastian W; John Hart, A

    2015-01-01

    We present the design of a concentric tube (CT) reactor for roll-to-roll chemical vapor deposition (CVD) on flexible substrates, and its application to continuous production of graphene on copper foil. In the CTCVD reactor, the thin foil substrate is helically wrapped around the inner tube, and translates through the gap between the concentric tubes. We use a bench-scale prototype machine to synthesize graphene on copper substrates at translation speeds varying from 25?mm/min to 500?mm/min, and investigate the influence of process parameters on the uniformity and coverage of graphene on a continuously moving foil. At lower speeds, high-quality monolayer graphene is formed; at higher speeds, rapid nucleation of small graphene domains is observed, yet coalescence is prevented by the limited residence time in the CTCVD system. We show that a smooth isothermal transition between the reducing and carbon-containing atmospheres, enabled by injection of the carbon feedstock via radial holes in the inner tube, is essential to high-quality roll-to-roll graphene CVD. We discuss how the foil quality and microstructure limit the uniformity of graphene over macroscopic dimensions. We conclude by discussing means of scaling and reconfiguring the CTCVD design based on general requirements for 2-D materials manufacturing. PMID:25997124

  18. Method and source for producing a high concentration of positively charged molecular hydrogen or deuterium ions

    International Nuclear Information System (INIS)

    A positive ion source is described for producing a beam of high concentration positively charged molecular ions when supplied with hydrogen or deuterium, and ion source comprising: a plasma chamber constructed so as to minimize the path length of positive ions in the chamber before such ions are extracted therefrom, electron emitting means positioned in the chamber, means for metering hydrogen or deuterium into the chamber, a plasma grid, extractor electrode means located outside the chamber adjacent to an alignment with the extraction opening of the plasma grid for extracting a beam of positive ions from the chamber through the extraction opening, the electron emitting means being located closely adjacent with respect to the plasma grid and closely adjacent to the extraction opening in the plasma grid so that the path length is short in relation to the mean free path of the hydrogen or deuterium molecules in the chamber to achieve a high concentration of hydrogen or deuterium ions and to minimize the production of other ions species by collisions of the positive hydrogen or deuterium ions with hydrogen or deuterium molecules

  19. Clinical study on high concentrations of sodium hyaluronate eye drops for moderate to severe dry eye

    Directory of Open Access Journals (Sweden)

    Yu-Jing Tian

    2014-06-01

    Full Text Available AIM: To observe the efficacy of high concentrations of sodium hyaluronate(3g/L SHfor moderate to severe dry eye. METHODS: Forty moderate to severe dry eye patients were included in the study according to the diagnosis criteria and randomized into two groups. The patients of the trial group received topical administration of high concentration sodium hyaluronate(3g/L, and those of the control group received sodium hyaluronate(1g/Lplus recombinant human epidermal growth factor. The dry eye symptom scores, ocular surface disease index(OSDIscores, tear film break-up time(BUT, Schirmer ? test and corneal fluorescein staining score were evaluated.All the indexes were compared between the two groups 2wk before and after treatment. RESULTS: There were no significant differences of the indicators between the two groups before treatment. After 2wk treatment, the differences were statistically significant compared to former except for the Schirmer ? test. Compared with the control group, the symptom scores and the OSDI scores were lowered. No significant differences were found in the other indicators between these two groups. CONCLUSION: Topical usage of highconcentrations of sodium hyaluronate(3g/Lis beneficial for remitting the ocular symptoms in moderate to severe dry eyes, and also improve the quality of life of patients.

  20. Prediction of Stress Concentration effect under Thermal and Dynamic loads on a High Pressure Turbine Rotor

    Directory of Open Access Journals (Sweden)

    R.Nagendra Babu

    2010-08-01

    Full Text Available Geometric discontinuities cause a large variation of stress and produce a significant increase in stress. The high stress due to the variation of geometry is called as ‘stress concentration’. This will increase when the loads are further applied. There are many investigators who have studied the stress distribution around the notches, grooves, and other irregularities of various machine components. This paper analyses the effects of thermal and fatigue load on a steam turbine rotor under the operating conditions. Stresses due to thermal and dynamic loads of High Pressure Steam Turbine Rotor of 210MW power station are found in two stages. A source code is developed for calculating the nominal stress at each section of HPT rotor. Maximum stress is obtained using FEA at the corresponding section. Thermal and Fatigue Stress Concentration Factors at each section are calculated. It is observed that the SCFdue to the combined effect of thermal and dynamic loads at the temperatures beyond 5400C is exceeding the safe limits.

  1. Strategies for surviving high concentrations of environmental ammonia in the swamp eel Monopterus albus.

    Science.gov (United States)

    Ip, Yuen K; Tay, Angeline S L; Lee, Kong H; Chew, Shit F

    2004-01-01

    The swamp eel Monopterus albus lives in muddy ponds, swamps, canals, and rice fields in the tropics. It encounters high concentrations of environmental ammonia (HEA) during dry seasons or during agricultural fertilization in rice fields. This study aimed at determining the tolerance of M. albus to environmental ammonia and at elucidating the strategies that it adopts to defend against ammonia toxicity in HEA. In the laboratory, M. albus exhibited very high environmental ammonia tolerance; the 48-, 72-, and 96-h median lethal concentrations of total ammonia at pH 7.0 and 28 degrees C were 209.9, 198.7, and 193.2 mM, respectively. It was apparently incapable of actively excreting ammonia against a concentration gradient. In addition, it did not detoxify ammonia to urea, the excretion of which would lead to a loss of nitrogen and carbon, during ammonia loading. The high tolerance of M. albus to HEA was attributable partially to its exceptionally high tolerance to ammonia at the cellular and subcellular levels. During the 144 h of exposure to 75 mM NH(4)Cl at pH 7.0, the ammonia contents in the muscle, liver, brain, and gut of M. albus reached 11.49, 15.18, 6.48, and 7.51 mu mol g(-1), respectively. Such a capability allowed the accumulation of high concentrations of ammonia in the plasma (3.54 mu mol mL(-1)) of M. albus exposed to HEA, which would reduce the net influx of exogenous ammonia. Subsequent to the buildup of internal ammonia levels, M. albus detoxified ammonia produced endogenously to glutamine. The glutamine contents in the muscle and liver reached 10.84 and 17.06 mu mol g(-1), respectively, after 144 h of exposure to HEA, which happened to be the highest known for fish. Unlike urea, the storage of glutamine in the muscle during ammonia loading allowed its usage for anabolic purposes when the adverse environmental condition subsides. Glutamine synthetase activity increased significantly in the liver and gut (2.8- and 1.5-fold, respectively) of specimens exposed to HEA for 144 h. These results suggest that the liver was the main site of ammonia detoxification and the gut was more than a digestive/absorptive organ in M. albus. Monopterus albus did not undergo a reduction in amino acid catabolism during the first 24 h of ammonia exposure. However, assuming a total inhibition of excretion of endogenous ammonia, there was a deficit of -312 mu mol N between the reduction in nitrogenous excretion (3,360 mu mol N) and the retention of nitrogen (3,048 mu mol N) after 72 h of aerial exposure. The deficit became much greater after 144 h, reaching a value of -3,243 mu mol N. These results suggest that endogenous ammonia production in M. albus was suppressed in order to prevent the newly established internal steady state concentration of ammonia from rising to an intolerable level after an extended period of exposure to HEA. PMID:15286913

  2. Xenobiotic metabolism and the mechanism(s) of benzene toxicity.

    Science.gov (United States)

    Snyder, Robert

    2004-10-01

    The investigation of the mechanism(s) of benzene toxicity/leukemogenesis over the past 50 years has been contemporaneous with developments in the study of xenobiotic metabolism. Research on the cytochrome P450 (CYP) enzyme system, and related systems in vivo and in vitro, which culminated in the isolation and reconstitution of the many CYPs, established pathways for the study of xenobiotic metabolism and its relationship to the biological activity of many chemicals. The essential role for metabolism of benzene as a precursor to the demonstration of benzene toxicity led to extensive studies of benzene metabolism, many of which will be reviewed here. Benzene toxicity/leukemogenesis, however, is a function of the bone marrow, a site remote from the liver where most benzene metabolism occurs. Studies of benzene metabolism have delineated the array of metabolites which appear to play a role in bone marrow damage, but further studies, both in vivo and in vitro, using appropriate animal models, will be needed to fully understand the impact of benzene and its metabolites on bone marrow function. PMID:15554234

  3. Study of gaseous benzene effects upon A549 lung epithelial cells using a novel exposure system.

    Science.gov (United States)

    Mascelloni, Massimiliano; Delgado-Saborit, Juana Maria; Hodges, Nikolas J; Harrison, Roy M

    2015-08-19

    Volatile organic compounds (VOCs) are ubiquitous pollutants known to be present in both indoor and outdoor air arising from various sources. Indoor exposure has increasingly become a major cause of concern due to the effects that such pollutants can have on health. Benzene, along with toluene, is one of the main components of the VOC mixture and is a known carcinogen due to its genotoxic effects. The aim of this study was to test the feasibility of an in vitro model to study the short-term effects of exposure of lung cells to airborne benzene. We studied the effects of exposure on DNA and the production of reactive oxygen species (ROS) in A549 cells, exposed to various concentrations of benzene (0.03; 0.1; 0.3ppm) in gaseous form using a custom designed cell exposure chamber. Results showed a concentration-dependent increase of DNA breaks and an increase of ROS production, confirming the feasibility of the experimental procedure and validating the model for further in vitro studies of exposure to other VOCs. PMID:26022717

  4. Evaluation of the reliability of high concentrator GaAs solar cells by means of temperature accelerated aging tests

    OpenAIRE

    Nun?ez Mendoza, Neftali; Gonza?lez Cipria?n, Jose? Ramo?n; Va?zquez Lo?pez, Manuel; Algora Del Valle, Carlos; Espinet Gonza?lez, Pilar

    2013-01-01

    ABSTRACT Evaluating the reliability, warranty period, and power degradation of high concentration solar cells is crucial to introducing this new technology to the market. The reliability of high concentration GaAs solar cells, as measured in temperature accelerated life tests, is described in this paper. GaAs cells were tested under high thermal accelerated conditions that emulated operation under 700 or 1050 suns over a period exceeding 10?000?h. Progressive power degradation was obse...

  5. Detection and monitoring of high stress concentration zones induced by coal mining using numerical and microseismic method

    OpenAIRE

    Senfaute, Gloria; Al Heib, Marwan; Josien, Jean-Pierre; Noirel, J.-F.

    2001-01-01

    Zones of high stress concentration induced by coal mining at a depth of 1250 meters in the Lorraine Collieries are detected and monitored using a combination of numerical and microseismic methods. Changes in the stress state induced by coal mining are estimated by means of numerical simulations. The areas of high stress concentration are located and monitored by local microseismic network. The study of microseismic activity recorded during mining made it possible to localise the zones of high...

  6. High-concentration boron doping of graphene nanoplatelets by simple thermal annealing and their supercapacitive properties

    Science.gov (United States)

    Yeom, Da-Young; Jeon, Woojin; Tu, Nguyen Dien Kha; Yeo, So Young; Lee, Sang-Soo; Sung, Bong June; Chang, Hyejung; Lim, Jung Ah; Kim, Heesuk

    2015-05-01

    For the utilization of graphene in various energy storage and conversion applications, it must be synthesized in bulk with reliable and controllable electrical properties. Although nitrogen-doped graphene shows a high doping efficiency, its electrical properties can be easily affected by oxygen and water impurities from the environment. We here report that boron-doped graphene nanoplatelets with desirable electrical properties can be prepared by the simultaneous reduction and boron-doping of graphene oxide (GO) at a high annealing temperature. B-doped graphene nanoplatelets prepared at 1000?°C show a maximum boron concentration of 6.04?±?1.44 at %, which is the highest value among B-doped graphenes prepared using various methods. With well-mixed GO and g-B2O3 as the dopant, highly uniform doping is achieved for potentially gram-scale production. In addition, as a proof-of-concept, highly B-doped graphene nanoplatelets were used as an electrode of an electrochemical double-layer capacitor (EDLC) and showed an excellent specific capacitance value of 448?F/g in an aqueous electrolyte without additional conductive additives. We believe that B-doped graphene nanoplatelets can also be used in other applications such as electrocatalyst and nano-electronics because of their reliable and controllable electrical properties regardless of the outer environment.

  7. High-concentration boron doping of graphene nanoplatelets by simple thermal annealing and their supercapacitive properties.

    Science.gov (United States)

    Yeom, Da-Young; Jeon, Woojin; Tu, Nguyen Dien Kha; Yeo, So Young; Lee, Sang-Soo; Sung, Bong June; Chang, Hyejung; Lim, Jung Ah; Kim, Heesuk

    2015-01-01

    For the utilization of graphene in various energy storage and conversion applications, it must be synthesized in bulk with reliable and controllable electrical properties. Although nitrogen-doped graphene shows a high doping efficiency, its electrical properties can be easily affected by oxygen and water impurities from the environment. We here report that boron-doped graphene nanoplatelets with desirable electrical properties can be prepared by the simultaneous reduction and boron-doping of graphene oxide (GO) at a high annealing temperature. B-doped graphene nanoplatelets prepared at 1000?°C show a maximum boron concentration of 6.04?±?1.44 at %, which is the highest value among B-doped graphenes prepared using various methods. With well-mixed GO and g-B2O3 as the dopant, highly uniform doping is achieved for potentially gram-scale production. In addition, as a proof-of-concept, highly B-doped graphene nanoplatelets were used as an electrode of an electrochemical double-layer capacitor (EDLC) and showed an excellent specific capacitance value of 448?F/g in an aqueous electrolyte without additional conductive additives. We believe that B-doped graphene nanoplatelets can also be used in other applications such as electrocatalyst and nano-electronics because of their reliable and controllable electrical properties regardless of the outer environment. PMID:25940534

  8. Anomalous thermoelectric power in conducting amorphous carbon thin films incorporating a high concentration of nitrogen

    International Nuclear Information System (INIS)

    We study the large enhancement of thermoelectric power (S) at low temperatures of a batch of conducting amorphous carbon (a-CNx) thin films containing high concentrations of nitrogen (nitrogen atomic fraction x = 15-23) as well as the anomalous variation of the sign of S with x. A transport model is proposed to explain trends in both S and conductivity (?), particularly their weak temperature dependence, which showed deviations from Mott's variable range hopping towards an extended-state conduction. The proposed expression for S(T) of this inhomogeneous carbon system describes a specific energy dependence of density of states, including contributions from delocalized states more clearly than that obtained from the analysis of ?(T). Although localized states at the Fermi level largely contribute to (hopping) transport at this high level of nitrogen incorporation, as suggested by the proposed electronic structure, subsequent annealing of these films at high temperature substantially modifies the films' electronic structure. Upon reducing the effect of defects both high value of S and its linear-temperature dependence together with an activated electrical conductivity are shown for the first time in a disordered carbon system.

  9. High-concentration boron doping of graphene nanoplatelets by simple thermal annealing and their supercapacitive properties

    Science.gov (United States)

    Yeom, Da-Young; Jeon, Woojin; Tu, Nguyen Dien Kha; Yeo, So Young; Lee, Sang-Soo; Sung, Bong June; Chang, Hyejung; Lim, Jung Ah; Kim, Heesuk

    2015-01-01

    For the utilization of graphene in various energy storage and conversion applications, it must be synthesized in bulk with reliable and controllable electrical properties. Although nitrogen-doped graphene shows a high doping efficiency, its electrical properties can be easily affected by oxygen and water impurities from the environment. We here report that boron-doped graphene nanoplatelets with desirable electrical properties can be prepared by the simultaneous reduction and boron-doping of graphene oxide (GO) at a high annealing temperature. B-doped graphene nanoplatelets prepared at 1000?°C show a maximum boron concentration of 6.04?±?1.44 at %, which is the highest value among B-doped graphenes prepared using various methods. With well-mixed GO and g-B2O3 as the dopant, highly uniform doping is achieved for potentially gram-scale production. In addition, as a proof-of-concept, highly B-doped graphene nanoplatelets were used as an electrode of an electrochemical double-layer capacitor (EDLC) and showed an excellent specific capacitance value of 448?F/g in an aqueous electrolyte without additional conductive additives. We believe that B-doped graphene nanoplatelets can also be used in other applications such as electrocatalyst and nano-electronics because of their reliable and controllable electrical properties regardless of the outer environment. PMID:25940534

  10. Intergranular fracture in irradiated Inconel X-750 containing very high concentrations of helium and hydrogen

    Science.gov (United States)

    Judge, Colin D.; Gauquelin, Nicolas; Walters, Lori; Wright, Mike; Cole, James I.; Madden, James; Botton, Gianluigi A.; Griffiths, Malcolm

    2015-02-01

    In recent years, it has been observed that Inconel X-750 spacers in CANDU reactors exhibits lower ductility with reduced load carrying capacity following irradiation in a reactor environment. The fracture behaviour of ex-service material was also found to be entirely intergranular at high doses. The thermalized flux spectrum in a CANDU reactor leads to transmutation of 58Ni to 59Ni. The 59Ni itself has unusually high thermal neutron reaction cross-sections of the type: (n, ?), (n, p), and (n, ?). The latter two reactions, in particular, contribute to a significant enhancement of the atomic displacements in addition to creating high concentrations of hydrogen and helium within the material. Microstructural examinations by transmission electron microscopy (TEM) have confirmed the presence of helium bubbles in the matrix and aligned along grain boundaries and matrix-precipitate interfaces. Helium bubble size and density are found to be highly dependent on the irradiation temperature and material microstructure; the bubbles are larger within grain boundary precipitates. TEM specimens extracted from fracture surfaces and crack tips provide information that is consistent with crack propagation along grain boundaries due to the presence of He bubbles.

  11. Health Risk Assessment of Zone 7 Contaminated with Benzene in the Environmental Liability Generated by the “March 18th Ex-Refinery” in Mexico City

    Directory of Open Access Journals (Sweden)

    García-Villanueva Luis Antonio

    2014-07-01

    Full Text Available Benzene is a constituent of oil regarded as a potential carcinogen, and therefore a dangerous compound. Its risk increases when spills occur, added to the effect of gravity and high mobility, it’s infiltrated into the ground, reaching the phreatic area until dissolved, contaminating the water. The objective of this research was to evaluate the health risk of environmental liabilities caused by the contamination with benzene in the "Ex-refinery March 18" in Mexico City. For twenty years were carried out remediation work –which started since 2008– and today this space has been converted into a recreational park. This environmental liability is divided into seven zones for purposes of remediation, although in this case only was considered the 7 zone. It also, took into account only the concentration of this hydrocarbon (average, percentil 75 and 95 present in the soil. The results, –from a total of 642 samples from 122 soil profiles–, before the remediation –biospray with vapor extraction–, showed a health risk by depth between 1.2 to 7.2 m, from 1.69E–07 to 1.2 1.25E–05 m to 4.8 m, which coincides with the phreatic level of aquitard, was the place where the highest level of health risk is present. After remediation, the measurements yielded 4.07E–07 to 1.2 m and 3.85E–07 to 4.8 m. These values indicate that the mass of benzene before decontamination exceeded the risk considered acceptable, 1.0E–06 at a depth of 4.8 m; after that, reductions below the acceptable risk were achieved, which shows that the remnant hydrocarbon does not represent a health risk.

  12. Competitive Nitration of Benzene-Fluorobenzene and Benzene-Toluene Mixtures: Orientation and Reactivity Studies Using HPLC

    Science.gov (United States)

    Blankespoor, Ronald L.; Hogendoorn, Stephanie; Pearson, Andrea

    2007-01-01

    The reactivity and orientation effects of a substituent are analyzed by using HPLC to determine the competitive nitration of the benzene-toluene and benzene-fluorobenzene mixtures. The results have shown that HPLC is an excellent instrumental method to use in analyzing these mixtures.

  13. Ultrasonic Studies on the Molecular Interactions of Uranyl Soaps in Benzene-dimethylsulphoxide Mixture

    Scientific Electronic Library Online (English)

    Anubhuti, Jain; Sanjay K., Upadhyaya.

    2013-08-14

    Full Text Available The ultrasonic measurements of solutions of uranyl caprylate and laurate in a mixture of 50/50 benzene-dimethylsulphoxide (V/V) have been used to determine the critical micellar concentration, ultrasonic velocity and various acoustic parameters at different temperatures. The results confirm that the [...] re is a significant interaction between uranyl soaps and the mixed organic solvent molecules.The values of critical micellar concentration of uranyl caprylate and laurate are in good agreement with those obtained from conductivity measurements.

  14. Optical and electrical characterization of high-concentration photovoltaic systems = Caracterización óptica y eléctrica de sistemas fotovoltaicos de alta concentración

    OpenAIRE

    Domínguez Domínguez, César

    2012-01-01

    The record efficiencies achieved by multijunction (MJ) solar cells have renewed the interest in concentrator photovoltaics (CPV), as the use of high concentration is necessary to reduce the area of these expensive devices and to maximize their efficiency. The promise is a reduction of the cost of the electricity generated as compared to flat plate PV. In order to improve the efficiency of these systems, intensive research is being carried out regarding concentrator cells, optics and integrati...

  15. Chlorpromazine, haloperidol, metoclopramide and domperidone release prolactin through dopamine antagonism at low concentrations but paradoxically inhibit prolactin release at high concentrations.

    OpenAIRE

    Besser, Gm; Delitala, G.; Grossman, A.; Stubbs, Wa; Yeo, T.

    1980-01-01

    1. The effects of chlorpromazine, haloperidol, metoclopramide and domperidone on the release of prolactin from perfused columns of dispersed rat anterior pituitary cells were studied. 2. Chlorpromazine, haloperidol, metoclopramide and domperidone antagonized the dopamine-mediated inhibition of prolactin release at low concentrations. 3. Each dopamine antagonist displaced the dose-response curve for dopamine-induced suppression of prolactin release to the right in a parallel manner. 4. At high...

  16. Arbuscular mycorrhizal fungi differentially affect the response to high zinc concentrations of two registered poplar clones

    Energy Technology Data Exchange (ETDEWEB)

    Lingua, Guido [Dipartimento di Scienze dell' Ambiente e della Vita, Universita del Piemonte Orientale ' Amedeo Avogadro' , Via Bellini 25/G, I-15100 Alessandria (Italy)], E-mail: guido.lingua@mfn.unipmn.it; Franchin, Cinzia [Dipartimento di Biologia evoluzionistica sperimentale, Universita di Bologna, Via Irnerio 42, I-40126 Bologna (Italy); Todeschini, Valeria [Dipartimento di Scienze dell' Ambiente e della Vita, Universita del Piemonte Orientale ' Amedeo Avogadro' , Via Bellini 25/G, I-15100 Alessandria (Italy); Castiglione, Stefano [Dipartimento di Biologia, Universita di Milano, Via Celoria 25, I-20100 Milano (Italy); Biondi, Stefania [Dipartimento di Biologia evoluzionistica sperimentale, Universita di Bologna, Via Irnerio 42, I-40126 Bologna (Italy); Burlando, Bruno [Dipartimento di Scienze dell' Ambiente e della Vita, Universita del Piemonte Orientale ' Amedeo Avogadro' , Via Bellini 25/G, I-15100 Alessandria (Italy); Parravicini, Valerio [Dipartimento di Biologia, Universita di Milano, Via Celoria 25, I-20100 Milano (Italy); Torrigiani, Patrizia [Dipartimento di Biologia evoluzionistica sperimentale, Universita di Bologna, Via Irnerio 42, I-40126 Bologna (Italy); Berta, Graziella [Dipartimento di Scienze dell' Ambiente e della Vita, Universita del Piemonte Orientale ' Amedeo Avogadro' , Via Bellini 25/G, I-15100 Alessandria (Italy)

    2008-05-15

    The effects of a high concentration of zinc on two registered clones of poplar (Populus alba Villafranca and Populus nigra Jean Pourtet), inoculated or not with two arbuscular mycorrhizal fungi (Glomus mosseae or Glomus intraradices) before transplanting them into polluted soil, were investigated, with special regard to the extent of root colonization by the fungi, plant growth, metal accumulation in the different plant organs, and leaf polyamine concentration. Zinc accumulation was lower in Jean Pourtet than in Villafranca poplars, and it was mainly translocated to the leaves; the metal inhibited mycorrhizal colonization, compromised plant growth, and, in Villafranca, altered the putrescine profile in the leaves. Most of these effects were reversed or reduced in plants pre-inoculated with G. mosseae. Results indicate that poplars are suitable for phytoremediation purposes, confirming that mycorrhizal fungi can be useful for phytoremediation, and underscore the importance of appropriate combinations of plant genotypes and fungal symbionts. - Inoculation with arbuscular mycorrhizal fungi can improve poplar tolerance to heavy metals in phytoremediation programmes.

  17. [Characteristics of sludge in treatment of high concentrated organic wastewater by swim-bed technology].

    Science.gov (United States)

    Yang, Hong; Yang, Jia-Li; Zhang, Yan; Furukawa, Kenji

    2009-02-15

    Based on the technology of conditional activated sludge process, swim-bed technology involving the novel biomass attachment material biofringe (BF) is one of the new and efficient advanced municipal wastewater treatments process. The process demonstrated effective treatment of high concentrated organic wastewater. When VLRs were from 1.7 kg/(m3 x d) to 4.5 kg/(m3 x d), 96% of average COD removal efficiencies and 80.7% of nitrification rate were achieved, respectively. The BF material allowed for attachment of large amounts of biomass. The mixed liquor suspended solid (MLSS) concentrations in the reactor reached 23 g/L at the highest during operation period, with holding 20-50 mL/g of SVI. An exponential law was found to be suitable to describe the variation of the viscosity as a function of MLSS. The granulation phenomenon of sludge was observed during the experiment. Protozoan and metazoans on the bio-film and suspended sludge were proved existing in the system by microscopic observation and DNA experiment. Observed sludge yields from 0.1046 to 0.1723 (MLSS/BOD) were obtained in swim-bed system. PMID:19402496

  18. Entropy Generation in Flow of Highly Concentrated Non-Newtonian Emulsions in Smooth Tubes

    Directory of Open Access Journals (Sweden)

    Rajinder Pal

    2014-10-01

    Full Text Available Entropy generation in adiabatic flow of highly concentrated non-Newtonian emulsions in smooth tubes of five different diameters (7.15–26.54 mm was investigated experimentally. The emulsions were of oil-in-water type with dispersed-phase concentration (? ranging from 59.61–72.21% vol. The emulsions exhibited shear-thinning behavior in that the viscosity decreased with the increase in shear rate. The shear-stress (? versus shear rate (?? data of emulsions could be described well by the power-law model: ?=K??n. The flow behavior index n was less than 1 and it decreased sharply with the increase in ? whereas the consistency index K increased rapidly with the increase in ? . For a given emulsion and tube diameter, the entropy generation rate per unit tube length increased linearly with the increase in the generalized Reynolds number ( Re_n on a log-log scale. For emulsions with ? ?65.15 % vol., the entropy generation rate decreased with the increase in tube diameter. A reverse trend in diameter-dependence was observed for the emulsion with ? of 72.21% vol. New models are developed for the prediction of entropy generation rate in flow of power-law emulsions in smooth tubes. The experimental data shows good agreement with the proposed models.

  19. Osmotic Pressure induced by Poly(ethylene glycol) at High Salt Concentrations

    Science.gov (United States)

    Sohn, Sungkyun; Strey, Helmut; Gido, Sam

    2006-03-01

    The osmotic pressure method is one of the most effective tools that can be used in controlling self-assembly of polymers in solution, especially of water-soluble biopolymers. This study investigated if there is a noticeable synergistic osmotic pressure increase between co-existing polymeric osmolyte and salt when extremely highly concentrated salt molecules are present both at sample subphase and stressing subphase. PEG 8,000 and LiBr were chosen as osmolyte and salt, respectively, since this model system can be directly applied to the case of silk protein self-assembly, where hydrogen bonding plays a major role. In addition to the conventional methods for measuring osmotic pressure, such as membrane osmometry, vapor pressure osmometry, and ultracentrifuge, an `equilibration method' that measures osmotic pressure relative to a reference with known osmotic pressure, was introduced. PEG 400 solution was chosen as the reference for this method. Osmotic pressure of aqueous LiBr solution up to 2.75M was measured and it was found that the synergistic effect was insignificant up to this salt concentration. Solution parameters and Arrhenius kinetics based on time-temperature relationship during the equilibration process were derived as well.

  20. A portable and high energy efficient desalination/purification system by ion concentration polarization

    Science.gov (United States)

    Kim, Sung Jae; Kim, Bumjoo; Kwak, Rhokyun; Kim, Geunbae; Han, Jongyoon

    2012-10-01

    The shortage of fresh water is one of the acute challenges that the world is facing now and, thus, energy efficient desalination strategies can provide substantial answers for the water-crisis. Current desalination methods utilizing reverse-osmosis and electrodialysis mechanisms required high power consumptions/large-scale infrastructures which do not make them appropriate for disaster-stricken area or underdeveloped countries. In addition, groundwater contamination by heavy metal compounds, such as arsenic, cadmium and lead, poses significant public health challenges, especially in developing countries. Existing water purification strategies for heavy metal removal are not readily applicable due to technological, environmental, and economical barriers. This presentation elucidates a novel desalination/purification process, where a continuous contaminated stream is divided into filtered and concentrated stream by the ion concentration polarization. The key distinct feature is that both salts and larger particles (cells, viruses, and microorganisms) are pushed away from the membrane, in continuous flow operations, eliminating the membrane fouling that plagues the membrane filtration methods. The power consumption is less than 5Wh/L, comparable to any existing systems. The energy and removal efficiency, and low cost manufacturability hold strong promises for portable, self-powered water purification/desalination system that can have significant impacts on water shortage in developing/rural part of the world.

  1. Arbuscular mycorrhizal fungi differentially affect the response to high zinc concentrations of two registered poplar clones

    International Nuclear Information System (INIS)

    The effects of a high concentration of zinc on two registered clones of poplar (Populus alba Villafranca and Populus nigra Jean Pourtet), inoculated or not with two arbuscular mycorrhizal fungi (Glomus mosseae or Glomus intraradices) before transplanting them into polluted soil, were investigated, with special regard to the extent of root colonization by the fungi, plant growth, metal accumulation in the different plant organs, and leaf polyamine concentration. Zinc accumulation was lower in Jean Pourtet than in Villafranca poplars, and it was mainly translocated to the leaves; the metal inhibited mycorrhizal colonization, compromised plant growth, and, in Villafranca, altered the putrescine profile in the leaves. Most of these effects were reversed or reduced in plants pre-inoculated with G. mosseae. Results indicate that poplars are suitable for phytoremediation purposes, confirming that mycorrhizal fungi can be useful for phytoremediation, and underscore the importance of appropriate combinations of plant genotypes and fungal symbionts. - Inoculation with arbuscular mycorrhizal fungi can improve poplar tolerance to heavy metals in phytoremediation programmes

  2. Fly ash used in solidification of highly concentrated sulfate chemical waste

    International Nuclear Information System (INIS)

    According to the criteria of radiowaste disposal, liquid chemical waste in BWR nuclear power plant is disposed by the processes of concentration, neutralization, and solidification. This project studies the feasibility of fly ash as an alternative in the solidification treatment. A non-radioactive simulate sample solution which contains Na2SO4, MgCl2, NaCl, etc. in total amount of 200 g/1, especially Na2SO4 up to 112 g/1, was prepared for the experiments. Portland cement Type I, Type V, and Portland cement with fly ash in different percentage replacements were mixed well with the sample respectively under the surfactant agent in existing and warming conditions. Compressive strength of the casted specimens were tested after different curing age. Results of laboratory test showed that fly ash used in solidification of highly concentrated sulfate liquid waste has improved quality significantly and saved cost largely. Therefore, a further demonstration test will be conducted at the power plant site. 4 references, 12 figures, 1 table

  3. Concentrations of radionuclides in cassava growing in high background radiation area and their transfer

    International Nuclear Information System (INIS)

    The concentrations of several natural radionuclides in common cassava (Manihot esculenta Crantz) growing in Yangjiang County, a high background radiation area in Guangdong Province, and their uptake from soil and distribution in the plant were investigated. The results show that the concentrations of natural uranium and thorium in cassava root are of the order of 10-6 g/kg, and those of radium-226, radium-228, lead-210 and polonium-210 are of the order of 10-11 Ci/kg. The highest level is 9.30 +- 0.30 x 10-11 Ci/kg (lead-210), and the lowest is 3.99 +- 0.20 x 10-11 Ci/kg (radium-226). The levels of natural uranium, thorium, radium-226 and polonium-210 in cassava are below the limits stipulated by the regulations for food hygiene in China, while the lead-210 level approaches the limit. It is noticeable that the highest level of radium-228 is 7.28 +- 1.03 x 10-11 Ci/kg, 10.4 times higher than the limit. The transfer of all he nuclides from soil to different parts of cassava shows a pattern contrary to that of he nuclides in the other regions where uranium-and radium-containing waste water and phosphate fertilizer are used in agriculture

  4. Temperature-dependent cross sections of benzene (C6H6) in the 7 - 15 µm region for Titan studies

    Science.gov (United States)

    Sung, Keeyoon; Toon, Geoffrey C.; Crawford, Timothy J.; Brown, Linda R.

    2014-11-01

    Benzene is one of the terminal species produced by hydrocarbon photochemistry, as well as a precursor species for polycyclic aromatic hydrocarbons (PAHs) on Titan. Benzene has already been detected in Titan’s stratosphere, but existing laboratory measurements in nitrogen mixtures are either at room temperature or at low-resolution, which are not sufficient for the quantitative analysis of Titan observations from Cassini/CIRS. We have therefore undertaken a laboratory investigation of the temperature dependence of benzene absorption cross sections between 630 and 1540 cm-1.Multiple spectra of pure and N2-mixture samples of C6H6 have been recorded at 230 - 296 K using the high-resolution Fourier transform spectrometer (Bruker IFS-125HR) and two cold cells (80 cm and 2 cm path length) at JPL. From these FT-IR spectra, the benzene cross sections have been derived for a few combination and difference bands (e.g., v17 - v20, v7 + v20, v4 + v11, etc.) as well as three strong fundamentals (v4, v13, v14) out of seven in this region. We note that v4 band centered at 674 cm-1 is the strongest among all the benzene bands. In addition, we have derived a HITRAN-format empirical ‘pseudo-linelist' for benzene containing line positions, intensities, and effective lower state energies (analogous to true spectroscopic line parameters), by fitting simultaneously all the observed laboratory spectra (see http://mark4sun.jpl.nasa.gov/data/spec/Pseudo/Readme for details). We will present preliminary results for the temperature-dependent cross sections of benzene. We also discuss their integrated intensities from the pseudoline intensities and compare them to those from earlier work.[Research described in this paper was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

  5. Synthesis of large diamond crystals containing high-nitrogen concentration at high pressure and high temperature using Ni-based solvent by temperature gradient method

    International Nuclear Information System (INIS)

    This paper reprots that with Ni-based catalyst/solvent and with a dopant of NaN3, large green single crystal diamonds with perfect shape are successfully synthesized by temperature gradient method under high pressure and high temperature in a China-type cubic anvil high-pressure apparatus (SPD-6 × 1200), and the highest nitrogen concentration reaches approximately 1214–1257 ppm calculated by infrared absorption spectra. The synthesis conditions are about 5.5 GPa and 1240–1300 °C. The growth behaviour of diamond with high-nitrogen concentration is investigated in detail. The results show that, with increasing the content of NaN3 added in synthesis system, the width of synthesis temperature region for growth high-quality diamonds becomes narrower, and the morphology of diamond crystal is changed from cube-octahedral to octahedral at same temperature and pressure, the crystal growth rate is slowed down, nevertheless, the nitrogen concentration doped in synthetic diamond increases

  6. High-concentration graphene dispersions with minimal stabilizer: a scaffold for enzyme immobilization for glucose oxidation.

    Science.gov (United States)

    Sun, Zhenyu; Vivekananthan, Jeevanthi; Guschin, Dmitrii A; Huang, Xing; Kuznetsov, Volodymyr; Ebbinghaus, Petra; Sarfraz, Adnan; Muhler, Martin; Schuhmann, Wolfgang

    2014-05-01

    Modified acrylate polymers are able to effectively exfoliate and stabilize pristine graphene nanosheets in aqueous media. Starting with pre-exfoliated graphite greatly promotes the exfoliation level. The graphene concentration is significantly increased up to 11?mg?mL(-1) by vacuum evaporation of the solvent from the dispersions under ambient temperature. TEM shows that 75?% of the flakes have fewer than five layers with about 18?% of the flakes consisting of monolayers. Importantly, a successive centrifugation and redispersion strategy is developed to enable the formation of dispersions with exceptionally high graphene-to-stabilizer ratio. Characterization by high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and Raman spectroscopy shows the flakes to be of high quality with very low levels of defects. These dispersions can act as a scaffold for the immobilization of enzymes applied, for example, in glucose oxidation. The electrochemical current density was significantly enhanced to be approximately six times higher than an electrode in the absence of graphene, thus showing potential applications in enzymatic biofuel cells. PMID:24677350

  7. Evidence of sulfur-bound reduced copper in bamboo exposed to high silicon and copper concentrations

    International Nuclear Information System (INIS)

    We examined copper (Cu) absorption, distribution and toxicity and the role of a silicon (Si) supplementation in the bamboo Phyllostachys fastuosa. Bamboos were maintained in hydroponics for 4 months and submitted to two different Cu (1.5 and 100 ?m Cu2+) and Si (0 and 1.1 mM) concentrations. Cu and Si partitioning and Cu speciation were investigated by chemical analysis, microscopic and spectroscopic techniques. Copper was present as Cu(I) and Cu(II) depending on plant parts. Bamboo mainly coped with high Cu exposure by: (i) high Cu sequestration in the root (ii) Cu(II) binding to amino and carboxyl ligands in roots, and (iii) Cu(I) complexation with both organic and inorganic sulfur ligands in stems and leaves. Silicon supplementation decreased the visible damage induced by high Cu exposure and modified Cu speciation in the leaves where a higher proportion of Cu was present as inorganic Cu(I)S compounds, which may be less toxic. - Highlights: • We examine the role of Si supplementation in mitigating Cu toxicity in bamboos. • In all plant parts, Cu was present under two oxidation states Cu(I) and Cu(II). • In stems and leaves, Cu(I) was bound to both organic and inorganic sulfur ligands. • Si supplementation decreased visible damages and modified Cu speciation. • The formation of an inorganic Cu(I)S compound may be involved in Cu storage. - Si supplementation modifies Cu speciation in a bamboo species used in phytoremediation

  8. Evidence of sulfur-bound reduced copper in bamboo exposed to high silicon and copper concentrations.

    Science.gov (United States)

    Collin, Blanche; Doelsch, Emmanuel; Keller, Catherine; Cazevieille, Patrick; Tella, Marie; Chaurand, Perrine; Panfili, Frédéric; Hazemann, Jean-Louis; Meunier, Jean-Dominique

    2014-04-01

    We examined copper (Cu) absorption, distribution and toxicity and the role of a silicon (Si) supplementation in the bamboo Phyllostachys fastuosa. Bamboos were maintained in hydroponics for 4 months and submitted to two different Cu (1.5 and 100 ?m Cu(2+)) and Si (0 and 1.1 mM) concentrations. Cu and Si partitioning and Cu speciation were investigated by chemical analysis, microscopic and spectroscopic techniques. Copper was present as Cu(I) and Cu(II) depending on plant parts. Bamboo mainly coped with high Cu exposure by: (i) high Cu sequestration in the root (ii) Cu(II) binding to amino and carboxyl ligands in roots, and (iii) Cu(I) complexation with both organic and inorganic sulfur ligands in stems and leaves. Silicon supplementation decreased the visible damage induced by high Cu exposure and modified Cu speciation in the leaves where a higher proportion of Cu was present as inorganic Cu(I)S compounds, which may be less toxic. PMID:24418975

  9. Improved high temperature solar absorbers for use in Concentrating Solar Power central receiver applications.

    Energy Technology Data Exchange (ETDEWEB)

    Stechel, Ellen Beth; Ambrosini, Andrea; Hall, Aaron Christopher; Lambert, Timothy L.; Staiger, Chad Lynn; Bencomo, Marlene

    2010-09-01

    Concentrating solar power (CSP) systems use solar absorbers to convert the heat from sunlight to electric power. Increased operating temperatures are necessary to lower the cost of solar-generated electricity by improving efficiencies and reducing thermal energy storage costs. Durable new materials are needed to cope with operating temperatures >600 C. The current coating technology (Pyromark High Temperature paint) has a solar absorptance in excess of 0.95 but a thermal emittance greater than 0.8, which results in large thermal losses at high temperatures. In addition, because solar receivers operate in air, these coatings have long term stability issues that add to the operating costs of CSP facilities. Ideal absorbers must have high solar absorptance (>0.95) and low thermal emittance (<0.05) in the IR region, be stable in air, and be low-cost and readily manufacturable. We propose to utilize solution-based synthesis techniques to prepare intrinsic absorbers for use in central receiver applications.

  10. Intergranular fracture in irradiated Inconel X-750 containing very high concentrations of helium and hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Judge, Colin D. [Atomic Energy of Canada, Limited, Chalk River, ON (Canada); Gauquelin, Nicolas [McMaster Univ., Hamilton, ON (Canada); Walters, Lori [Atomic Energy of Canada, Limited, Chalk River, ON (Canada); Wright, Mike [Atomic Energy of Canada, Limited, Chalk River, ON (Canada); Cole, James I. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Madden, James [Idaho National Lab. (INL), Idaho Falls, ID (United States); Botton, Gianluigi A. [McMaster Univ., Hamilton, ON (Canada); Griffiths, Malcolm [Atomic Energy of Canada, Limited, Chalk River, ON (Canada)

    2015-02-01

    In recent years, it has been determined that Inconel X-750 CANDU spacers have lost strength and material ductility following irradiation in reactor. The irradiated fracture behaviour of ex-service material was also found to be entirely intergranular. The heavily thermalized flux spectrum in a CANDU reactor results in transmutation of 58Ni to 59Ni. The 59Ni itself has unusually high thermal neutron reaction cross-sections of the type: (n, ?), (n, p), and (n,?). The latter two reactions, in particular, contribute to a significant enhancement of the atomic displacements in addition to creating high concentrations of hydrogen and helium within the material. Metallographic examinations by transmission electron microscopy (TEM) have confirmed the presence of helium bubbles in the matrix and aligned along grain boundaries and matrix-precipitate interfaces. He bubble size and density are found to be highly dependent on the irradiation temperature and material microstructure; the bubbles are larger within grain boundary precipitates. TEM specimens extracted from fracture surfaces and crack tips give direct evidence linking crack propagation with grain boundary He bubbles.

  11. Graphene oxide as efficient high-concentration formaldehyde scavenger and reutilization in supercapacitor.

    Science.gov (United States)

    Liang, Hongyu; Bu, Yongfeng; Zhang, Yutian; Zhang, Junyan

    2015-04-15

    Graphene oxide (GO) was investigated as a low-cost and high-efficient scavenger for high-concentration formaldehyde in alkali media. It showed very high removal capacity, 411 mg of formaldehyde per milligram of GO, and strong resistant to temperature changes. Additionally, the used GO can be easily renewed by a simple electrochemical method. By analyzing the componential and electrochemical characterizations of GO before and after use, the results showed that the degradation mechanism of formaldehyde is a collaborative process of chemical oxidation and physical adsorption, and the former dominates the degradation process. With the aid of oxygen-containing groups in GO, most formaldehyde can be easily oxidized by GO in alkaline media (this is equivalent to GO was reduced by formaldehyde). On the other hand, the used GO (reduced GO, noted as rGO) exhibits more ideal electronic double-layer capacitor (EDLC) feature than GO, along with higher rate capacitance (up to 136 F g(-1) at 50 A g(-1)). In short, GO is not only an efficient formaldehyde scavenger, but the used GO (rGO) can serve as promising electrical energy storage material. This study provides new insights for us to reutilize the discarded adsorbents generated from the environmental protection. PMID:25590697

  12. High-temperature maximum concentrations of paramagnetic centers during thermal treatment of solid fuel

    Energy Technology Data Exchange (ETDEWEB)

    Bel' kevich, P.I.; Lyubchenko, L.S.; Navosha, Yu.Yu.; Osika, V.A.; Strigutskii, V.P.; Tomson, A.Eh.

    1986-09-01

    The theory is checked which is generally accepted in literature of appearance (at 400-600 C) of maximum concentration of paramagnetic centers formed during thermal treatment of organic compounds and it is discovered that this takes place due to a loss of considerable amounts of paramagnetic absorption as a result of reduction in relaxation periods. Tests were made on cotton grass peat with a high degree of metamorphism (55-60%), thus the main signal was controlled by humic substances. Thermal treatment was carried out at 200-600 C in an oven in a stream of nitrogen. Changes are discussed taking place at different temperature ranges. Structural parameters of peat before and after thermal treatment were studied on a DRON-2.0 X-ray diffractometer. Electron paramagnetic resonance spectra were recorded on REh-1301 radiospectrometer and apparatus Varian E-112 at 300 K and 77 K in vacuum and air atmosphere. Results of the tests are given. 24 references.

  13. EPRI 25kW high concentration photovoltaic integrated array concept and associated economics

    International Nuclear Information System (INIS)

    This paper describes a cost effective photovoltaic array design for the high concentration technology being developed by the Electric Power Research Institute for utility scale applications. The concept of an ''integrated array'' is to attach Fresnel lens parquets directly to the front of the tracker structure and PV panels directly to the back of the structure thereby eliminating redundant structural components. The concept also incorporates the maximum use of automated manufacturing techniques for all components thereby minimizing material waste, fabrication and assembly labor. This paper also describes the results of a first approach cost and economic study for the technology which shows the potential for levelized energy cost below $0.10/kWh for a 50 MWac plant given a mature technology

  14. DIFFUSION COEFFICIENTS IN POLYMER-SOLVENT SYSTEMS FOR HIGHLY CONCENTRATED POLYMER SOLUTIONS

    Directory of Open Access Journals (Sweden)

    R.A. Reis

    2001-12-01

    Full Text Available The Vrentas/Duda proposal for the diffusion of polymer-solvent systems, which is based on the free-volume theory, was employed in correlating and predicting mutual diffusion coefficients in highly concentrated polymer solutions. It has been observed that the predictive version of the model is capable of qualitatively representing the experimental data, while the use of an adjustable parameter greatly improves the performance of the model. The systems studied were poly(vinyl acetate-toluene and Neoprene-acetone, and a comparison between experimental data and calculated values from the Vrentas/Duda model is reported. A new experimental apparatus based on the sorption technique was built to provide reliable diffusivity data on the Neoprene-acetone system.

  15. Phase volume holograms in PMMA layers under high concentration of phenanthrenequinone

    Science.gov (United States)

    Mahilny, U. V.; Marmysh, D. N.; Stankevich, A. I.; Tolstik, A. L.; Matusevich, V.; Kowarschik, R.

    2006-05-01

    We demonstrate a possibility to write efficient and thermally stable volume holographic gratings in a glassy polymer material based on PMMA and phenanthrenequinone with layers prepared by casting the liquid solution of ingredients on a substrate and drying to a solid state. A high concentration of phenanthrenequinone (up to 4 mol.%) makes it possible to use photosensitive layers of lower thicknesses (50 - 180 ?m) for the recording of efficient holographic gratings. The exposing is followed by a thermal amplification of the grating due to diffusion of residual phenanthrenequinone molecules and fixation by an incoherent optical illumination. We present experimental temporal curves of the refractive index modulation and diffraction efficiency both under the exposure and the heating process. The behavior of the gratings under temperatures up to 140°C has been studied.

  16. Rapid concentration and high pressure liquid chromatographic determination of atrazine and simazine herbicides in water

    International Nuclear Information System (INIS)

    A simple fast method for extracting and concentrating atrazine and simazine in water using C18 sep-pakTm cartridges (Waters Association Inc., Milford, Massachuaetts) and subsequent determination of the herbicides using reversed-phase high pressure liquid chromatography (HPLC) has been developed. A 500 ml water sample containing atrazine and simazine was passed through a C18 sep-pak cartridge and the absorbed herbicides eluted with dichloromethane. After evaporation of the solvent, atrazine and simazine were determined using reversed-phase HPLC. An utraviolet(UV) detector at a wavelength of 230 nm or 254 nm was used to detect two herbicides. Detection limits of 1ppb and 4ppb were reached with the wavelengths 230nm and 254 nm respectively. (author)

  17. A computer program for the simulation of evaporation of natural waters to high concentration

    Science.gov (United States)

    Risacher, François; Clement, Alain

    2001-03-01

    EQL/EVP is a FORTRAN 90 program that simulates the evaporation of dilute waters as well as concentrated brines. The code calculates stepwise the composition of the evaporated solution and the amounts of precipitated minerals. Activity coefficients are based on the Pitzer's interaction model which allows calculation to high ionic strength. The Newton-Raphson method is used to solve a set of linear mass-balance and non-linear mass-action equations. The simulation may be carried out in equilibrium mode where minerals are allowed to redissolve into the solution or in fractional crystallization mode where minerals are removed as they precipitate. Temperature dependence of various parameters and mineral solubility products are tentatively included between 0 and 50°C. The code processes all invariant points: those where the activity of water is constrained by several minerals and the invariant end-points. The code may be a useful tool for understanding hydrological and geochemical processes in arid regions.

  18. High-resolution Z-contrast imaging and hole concentration mapping of YBCO thin films

    International Nuclear Information System (INIS)

    Atomic-resolution Z-contrast electron microscopy provides a directly interpretable image showing the location of high-Z atomic columns without the need for any structural models. Usually, the type of column may be identified from its intensity, and the structure and morphology of interfaces, ultrathin films, and superlattices are directly revealed. This has generated many insights into growth and relaxation phenomena. Since the Z-contrast image uses only electrons scattered through large angles, electron energy loss spectroscopy may be performed simultaneously using the transmitted beam, providing information on the local hole concentration from the fine structure of the oxygen-K absorption edge. The resolution achieved is below the coherence length, allowing a microscopic interpretation of transport properties. 7 figs, 14 refs

  19. Water temperature and concentration measurements within the expanding blast wave of a high explosive

    Science.gov (United States)

    Carney, J. R.; Lightstone, J. M.; Piecuch, S.; Koch, J. D.

    2011-04-01

    We present an application of absorption spectroscopy to directly measure temperature and concentration histories of water vapor within the expansion of a high explosive detonation. While the approach of absorption spectroscopy is well established, the combination of a fast, near-infrared array, broadband light source, and rigid gauge allow the first application of time-resolved absorption measurements in an explosive environment. The instrument is demonstrated using pentaerythritol tetranitrate with a sampling rate of 20 kHz for 20 ms following detonation. Absorption by water vapor is measured between 1335 and 1380 nm. Water temperatures are determined by fitting experimental transmission spectra to a simulated database. Water mole fractions are deduced following the temperature assignment. The sources of uncertainty and their impact on the results are discussed. These measurements will aid the development of chemical-specific reaction models and the predictive capability in technical fields including combustion and detonation science.

  20. Water temperature and concentration measurements within the expanding blast wave of a high explosive

    International Nuclear Information System (INIS)

    We present an application of absorption spectroscopy to directly measure temperature and concentration histories of water vapor within the expansion of a high explosive detonation. While the approach of absorption spectroscopy is well established, the combination of a fast, near-infrared array, broadband light source, and rigid gauge allow the first application of time-resolved absorption measurements in an explosive environment. The instrument is demonstrated using pentaerythritol tetranitrate with a sampling rate of 20 kHz for 20 ms following detonation. Absorption by water vapor is measured between 1335 and 1380 nm. Water temperatures are determined by fitting experimental transmission spectra to a simulated database. Water mole fractions are deduced following the temperature assignment. The sources of uncertainty and their impact on the results are discussed. These measurements will aid the development of chemical-specific reaction models and the predictive capability in technical fields including combustion and detonation science

  1. High dielectric permittivity elastomers from well-dispersed expanded graphite in low concentrations

    DEFF Research Database (Denmark)

    Daugaard, Anders Egede; Hassouneh, Suzan Sager

    2013-01-01

    The development of elastomer materials with a high dielectric permittivity has attracted increased interest over the last years due to their use in for example dielectric electroactive polymers. For this particular use, both the electrically insulating properties - as well as the mechanical properties of the elastomer - have to be tightly controlled in order not to destroy favorable elastic properties by the addition of particles. In the following, expanded graphite in low concentrations (up to 5 wt%) are investigated as a possible candidate as filler materials in very soft elastomers, which by the addition of traditional fillers in the necessary amounts would either lose their stability or their softness. Furthermore the influence of several mixing procedures on the electrical and mechanical properties is investigated. © 2013 SPIE.

  2. Microwave enhanced Fenton-like process for the treatment of high concentration pharmaceutical wastewater

    International Nuclear Information System (INIS)

    This paper explored a novel process for wastewater treatment, i.e. microwave enhanced Fenton-like process. This novel process was introduced to treat high concentration pharmaceutical wastewater with initial COD loading of 49,912.5 mg L-1. Operating parameters were investigated and the optimal condition included as follows: microwave power was 300 W, radiation time was 6 min, initial pH was 4.42, H2O2 dosage was 1300 mg L-1 and Fe2(SO4)3 dosage was 4900 mg L-1, respectively. Within the present experimental condition used, the COD removal and UV254 removal reached to 57.53% and 55.06%, respectively, and BOD5/COD was enhanced from 0.165 to 0.470. The variation of molecular weight distribution indicated that both macromolecular substances and micromolecular substances were eliminated quite well. The structure of flocs revealed that one ferric hydrated ion seemed to connect with another ferric hydrated ion and/or organic compound molecule to form large-scale particles by means of van der waals force and/or hydrogen bond. Subsequently, these particles aggregated to form flocs and settled down. Comparing with traditional Fenton-like reaction and conventional heating assisted Fenton-like reaction, microwave enhanced Fenton-like process displayed superior treatment efficiency. Microwave was in favor of improving the degradation efficiency, the settling quality of sludn efficiency, the settling quality of sludge, as well as reducing the yield of sludge and enhancing the biodegradability of effluent. Microwave enhanced Fenton-like process is believed to be a promising treatment technology for high concentration and biorefractory wastewater.

  3. High concentrations of KCl release noradrenaline from noradrenergic neurons in the rat anococcygeus muscle

    Directory of Open Access Journals (Sweden)

    C.B.L. Araujo

    2003-01-01

    Full Text Available The aim of the present study was to investigate the effects of high concentrations of KCl in releasing noradrenaline from sympathetic nerves and its actions on postsynaptic alpha-adrenoceptors. We measured the isotonic contractions induced by KCl in the isolated rat anococcygeus muscle under different experimental conditions. The contractile responses induced by KCl were inhibited by alpha-adrenoceptor antagonists in 2.5 mM Ca2+ solution. Prazosin reduced the maximum effect from 100 to 53.9 ± 10.2% (P<0.05 while the pD2 values were not changed. The contractile responses induced by KCl were abolished by prazosin in Ca2+-free solution (P<0.05. Treatment of the rats with reserpine reduced the maximum effect induced by KCl as compared to the contractile responses induced by acetylcholine from 339.5 ± 157.8 to 167.3 ± 65.5% (P<0.05, and increased the pD2 from 1.57 ± 0.01 to 1.65 ± 0.006 (P<0.05, but abolished the inhibitory effect of prazosin (P<0.05. In contrast, L-NAME increased the contractile responses induced by 120 mM KCl by 6.2 ± 2.3% (P<0.05, indicating that KCl could stimulate the neurons that release nitric oxide, an inhibitory component of the contractile response induced by KCl. Our results indicate that high concentrations of KCl induce the release of noradrenaline from noradrenergic neurons, which interacts with alpha1-adrenoceptors in smooth muscle cells, producing a contractile response in 2.5 mM Ca2+ (100% and in Ca2+-free solution, part of which is due to a direct effect of KCl on the rat anococcygeus muscle.

  4. Fibrinogen and thrombin concentrations are critical for fibrin glue adherence in rat high-risk colon anastomoses

    Scientific Electronic Library Online (English)

    Eliseo Portilla-de, Buen; Abel, Orozco-Mosqueda; Caridad, Leal-Cortés; Gonzalo, Vázquez-Camacho; Clotilde, Fuentes-Orozco; Andrea Socorro, Alvarez-Villaseñor; Michel Dassaejv, Macías-Amezcua; Alejandro, González-Ojeda.

    2014-04-01

    Full Text Available OBJECTIVE: Fibrin glues have not been consistently successful in preventing the dehiscence of high-risk colonic anastomoses. Fibrinogen and thrombin concentrations in glues determine their ability to function as sealants, healers, and/or adhesives. The objective of the current study was to compare [...] the effects of different concentrations of fibrinogen and thrombin on bursting pressure, leaks, dehiscence, and morphology of high-risk ischemic colonic anastomoses using fibrin glue in rats. METHODS: Colonic anastomoses in adult female Sprague-Dawley rats (weight, 250-350 g) treated with fibrin glue containing different concentrations of fibrinogen and thrombin were evaluated at post-operative day 5. The interventions were low-risk (normal) or high-risk (ischemic) end-to-end colonic anastomoses using polypropylene sutures and topical application of fibrinogen at high (120 mg/mL) or low (40 mg/mL) concentrations and thrombin at high (1000 IU/mL) or low (500 IU/mL) concentrations. RESULTS: Ischemia alone, anastomosis alone, or both together reduced the bursting pressure. Glues containing a low fibrinogen concentration improved this parameter in all cases. High thrombin in combination with low fibrinogen also improved adherence exclusively in low-risk anastomoses. No differences were detected with respect to macroscopic parameters, histopathology, or hydroxyproline content at 5 days post-anastomosis. CONCLUSIONS: Fibrin glue with a low fibrinogen content normalizes the bursting pressure of high-risk ischemic left-colon anastomoses in rats at day 5 after surgery.

  5. Development and impact of hooks of high droplet concentration on remote southeast Pacific stratocumulus

    Directory of Open Access Journals (Sweden)

    R. C. George

    2013-07-01

    Full Text Available Over the southeastern Pacific (SEP, droplet concentration (Nd in the typically unpolluted marine stratocumulus west of 80° W (> 1000 km offshore is periodically strongly enhanced in zonally elongated "hook"-shaped features that increase albedo. Here, we examine three hook events using the chemistry version of the Weather Research and Forecasting model (WRF-Chem with 14 km horizontal resolution, satellite data, and aircraft data from the VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx. A particularly strong hook yields insights into the development, decay, and radiative impact of these features. Hook development occurs with Nd increasing to polluted levels over the remote ocean primarily due to entrainment of cloud condensation nuclei (CCN from the lower free troposphere (FT. The feature advects northwestward until the FT CCN source is depleted, after which Nd decreases over a few days due to precipitation and dilution. The model suggests that the FT CCN source supplying the hook consists of high concentrations of small accumulation-mode aerosols that contribute a relatively small amount of aerosol mass to the MBL, in agreement with near-coast VOCALS measurements of polluted layers in the FT. The aerosol particles in this hook originate mainly from a pulse of offshore flow that transports Santiago-region (33–35° S emissions to the remote marine FT. To provide pollution CCN that can sustain hooks, the FT transport of pollution plumes to the remote ocean requires strong, deep offshore flow. Such flow is favored by a trough approaching the South American coast and a southeastward shift of the climatological subtropical high-pressure system. The model simulations show precipitation suppression in the hook and a corresponding increase in liquid water path (LWP compared with a simulation without anthropogenic sources. LWP also increases as the hook evolves over time due to increasing stability and decreasing subsidence. WRF-Chem suggests that dimethyl sulfide (DMS significantly influences the aerosol number and size distributions in a hook, but that hooks do not form without FT CCN. The Twomey effect contributes ~ 50–70% of the albedo increase due to the presence of the hook, while secondary aerosol indirect effects and meteorological influences also contribute significantly. The source of hook aerosols is difficult to determine with the available observations alone. The model provides further explanation of the factors influencing hook formation. Two other weaker hooks during VOCALS-REx are not as well simulated but are also associated with FT offshore flow near Santiago. Hooks demonstrate the importance of free-tropospheric transport of aerosols in modulating the droplet concentration in the southeastern Pacific stratocumulus deck, and present a formidable challenge to simulate accurately in large-scale models.

  6. Miniaturized, High Flow, Low Dead Volume Pre-Concentrator for Trace Contaminants in Water under Microgravity Conditions Project

    National Aeronautics and Space Administration — Thorleaf Research, Inc. proposes to develop a miniaturized high flow, low dead-volume pre-concentrator for monitoring trace levels of contaminants in water under...

  7. Modeling Studies on the Transport of Benzene and H2S in CO2-Water Systems

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, L.; Spycher, N.; Xu, T.; Apps, J.; Kharaka, Y.; Birkholzer, J.T.

    2010-11-05

    In this study, reactive transport simulations were used to assess the mobilization and transport of organics with supercritical CO{sub 2} (SCC), and the co-injection and transport of H{sub 2}S with SCC. These processes were evaluated at conditions of typical storage reservoirs, and for cases of hypothetical leakage from a reservoir to an overlying shallower fresh water aquifer. Modeling capabilities were developed to allow the simulation of multiphase flow and transport of H{sub 2}O, CO{sub 2}, H{sub 2}S, as well as specific organic compounds (benzene), coupled with multicomponent geochemical reaction and transport. This included the development of a new simulator, TMVOC-REACT, starting from existing modules of the TOUGH2 family of codes. This work also included an extensive literature review, calculation, and testing of phase-partitioning properties for mixtures of the phases considered. The reactive transport simulations presented in this report are primarily intended to illustrate the capabilities of the new simulator. They are also intended to help evaluate and understand various processes at play, in a more qualitative than quantitative manner, and only for hypothetical scenarios. Therefore, model results are not intended as realistic assessments of groundwater quality changes for specific locations, and they certainly do not provide an exhaustive evaluation of all possible site conditions, especially given the large variability and uncertainty in hydrogeologic and geochemical parameter input into simulations. The first step in evaluating the potential mobilization and transport of organics was the identification of compounds likely to be present in deep storage formations, and likely to negatively impact freshwater aquifers if mobilized by SCC. On the basis of a literature review related to the occurrence of these organic compounds, their solubility in water and SCC, and their toxicity (as reflected by their maximum contaminant levels MCL), benzene was selected as a key compound for inclusion into numerical simulations. Note that considering additional organic compounds and/or mixtures of such compounds in the simulations was beyond the scope of this study, because of the effort required to research, calculate, and validate the phase-partitioning data necessary for simulations. The injection of CO{sub 2} into a deep saline aquifer was simulated, followed by modeling the leaching of benzene by SCC and transport of benzene to an overlying aquifer along a hypothetical leakage pathway. One- and two-dimensional models were set up for this purpose. The target storage formation was assumed to initially contain about 10{sup -4} ppm benzene. Model results indicate that: (1) SCC efficiently extracts benzene from the storage formation. (2) Assuming equilibrium, the content of benzene in SCC is roportional to the concentration of benzene in the aqueous and solid phases. (3) Benzene may co-migrate with CO{sub 2} into overlying aquifers if a leakage pathway is present. Because the aqueous solubility of benzene in contact with CO{sub 2} is lower than the aqueous solubility of CO{sub 2}, benzene is actually enriched in the CO{sub 2} phase as the plume advances. (4) For the case studied here, the resulting aqueous benzene concentration in the overlying aquifer is on the same order of magnitude as the initial concentration in the storage formation. This generic modeling study illustrates, in a semi-quantitative manner, the possible mobilization of benzene by SCC. The extent to which the mobilization of this organic compound evolves temporally and spatially depends on a large number of controlling parameters and is largely site specific. Therefore, for more 'truly' predictive work, further sensitivity studies should be conducted, and further modeling should be integrated with site-specific laboratory and/or field experimental data. The co-injection of H{sub 2}S with CO{sub 2} into a deep saline aquifer was also simulated. In addition, the model considered leakage of the supercritical CO{sub 2}+H{sub 2}S mixture along a pref

  8. Leaching of high-solids, attritor-ground chalcopyrite concentrate by in situ generated ferric sulfate solution

    Science.gov (United States)

    Tiwari, B. L.; Kolbe, J.; Hayden, H. W.

    1980-03-01

    Leaching of attritor-ground chalcopyrite concentrate by acidified ferric sulfate, generated in situ, has been studied. Air and oxygen alone and mixed with sulfur dioxide were tested as oxidizing agents. A specially designed reactor, which allowed n situ oxidation of ferrous sulfate, permitted the leaching of a 20 pct solids slurry with high copper recovery. The leachate contained ~ 53 g/l copper, a high enough concentration that solvent extraction may not be necessary.

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

    Directory of Open Access Journals (Sweden)

    LIU Shou-Xin,LIU Zheng-Feng

    2009-03-01

    Full Text Available TiO2/ACF composite was prepared by improved solª²gel method using Ti(OBu4 as titanium source. TiO2 precursor was loaded on activated carbon fiber (ACF by dip-coating method. X-ray diffraction (XRD, scanning electron microscopy (SEM and N2 (77K adsorption were used to characterize the obtained composite. High concentration gaseous benzene in a staticª²mode photocatalytic reactor was used as model compound for photocatalytic activity test. Gas chromatographª²mass spectrum (GC-MS was used for intermediates identification. The results show that TiO2 can form perfect thin film on ACF surface. With the increase of dipª²coating times, surface area of TiO2/ACF decrease, thickness of TiO2 film increase, then split and even fall off. Complete anatase can be formed for the sample calcinated at 400¡?nd phase transformation of anatase to rutile occurrs at 700¡?The crystal size of TiO2 decrease with the increase of calcination temperature. The sample of TiO2/ACF-400-2 calcinated at 400¡?nd dip-coated twice exhibits the highest activity for benzene removal. Intermediate analysis result reveals that no toxic of phenol and quinine compound is detected.

  10. Dog age and breeds associated with high plasma cholesterol and triglyceride concentrations.

    Science.gov (United States)

    Usui, Shiho; Mizoguchi, Yasushi; Yasuda, Hidemi; Arai, Nobuaki; Koketsu, Yuzo

    2014-03-01

    The objectives of this study were to set specific dog breed and sex standards for total cholesterol (T-Cho) and total triglyceride (T-TG) concentrations in dogs and to quantify the associations between dog age and concentrations of both lipids for different breeds. Increased age was associated with higher T-Cho and T-TG concentrations in all five breed groups (P<0.05); T-Cho concentrations increased by 62.5 mg/dl between 9 and 16 years of age, and T-TG concentrations increased by 4.8 mg/dl per year of age (P<0.05). Miniature Schnauzers had the highest T-Cho concentrations of the studied breeds, while Miniature Dachshunds had the lowest concentrations (P<0.05). Veterinarians should consider dog age and breed when they use the lipid concentrations for diagnostic purposes. PMID:24107429

  11. Calibration Of Collimated Flash Tester For High-Concentration Photovoltaic Panels

    Science.gov (United States)

    Green, Evan; Horne, Steve; Taylor, Sean; O'Bryan, Jon; Luo, Xin

    2011-12-01

    Accurate high volume manufacturing final test of high-concentration photovoltaic (HCPV) panels is challenging owing to the spectral sensitivity of multi-junction solar cells, the inherently small angular acceptance, and the elevated temperature during standard operating conditions (CSOC). An industrialized HCPV solar simulator developed in parallel with SolFocus first generation SF-1000S product has been previously discussed. Validation of the regression of simulator performance measurements from test conditions to CSOC was achieved by correlation of solar simulator and on-sun results using more than 100 SF-1000P panels. The second generation SF-1100S product incorporates a number of design and manufacturing advances including more efficient multi-junction solar cells, more thermally conductive receivers, more transmissive collection optics, and an optimized backpan, as well as a larger collection area. Each of these improvements can affect the accuracy of the regression from simulator test condition to SOC. To ensure that the SF-1100S product meets industry needs for power accuracy, we discuss the flash test methods and on-sun tests performed to quantify the thermal and optical parameters required for accurate regression to SOC. For cost reasons, cell temperature in standard commercial HCPV panels is not directly instrumented, hence we applied multiple independent measurement methods to ensure accurate estimation. We present best results for measurement of PV cell temperature under operating conditions comparing several methods. We review the correlation between normalized factory test results and standard operating conditions, along with sources of variance in the measurements.

  12. Chemical effects of a high CO2 concentration in oxy-fuel combustion of methane

    DEFF Research Database (Denmark)

    Glarborg, Peter; Bentzen, L.L.B.

    2008-01-01

    The oxidation of methane in an atmospheric-pres sure flow reactor has been studied experimentally under highly diluted conditions in N-2 and CO2, respectively. The stoichiometry was varied from fuel-lean to fuel-rich, and the temperatures covered the range 1200-1800 K. The results were interpreted in terms of a detailed chemical kinetic mechanism for hydrocarbon oxidation. On the basis of results of the present study, it can be expected that oxy-fuel combustion will lead to strongly increased CO concentrations in the near-burner region. The CO2 present will compete with O-2 for atomic hydrogen and lead to formation of CO through the reaction CO2 + H reversible arrow CO + OH. Reactions of CO2 with hydrocarbon radicals may also contribute to CO formation. The most important steps are those of singlet and triplet CH2 with CO2, while other radicals such as CH3 and CH are less important for consuming CO2. The high local CO levels may have implications for near-burner corrosion and stagging, but increased problems with CO emission in oxy-fuel combustion are not anticipated.

  13. Development of the method for determination of technetium in environmental high concentrated salt samples

    International Nuclear Information System (INIS)

    Technetium is a one of product of nuclear fission of uranium and therefore could be found in a trace concentration in the Earth's crust. It was estimated that a kilogram of uranium contains 1 nanogram (10-9 g) of technetium. However, besides of naturally occurred Tc, in the last several decades its relatively high amount was artificially produced in the nuclear reactors by the thermal neutron fission of 235U and 239Pu reactor fuels with the fission yield product of 99Tc of about 6.1%. The 99Tc has a half-life of 2.13*105 a, giving a specific activity of 650 MBq g-1 and decays by emission of ?-1 with Emax 300 keV. It has been released into the environment as the results of nuclear weapons testing and low- and intermediate-levels waste disposal, and will be an important component of high level wastes when these are finally disposed. Geochemically, Tc exists in two stable oxidation states depending on the redox conditions; it forms reduced species, predominantly Tc4+ and its complexes and compounds, however could also occurs as Tc (VII), which forms the pertechnetate anion, [TcO4-]. The environmental redox chemistry of technetium is thus very important in governing its mobility. (orig.)

  14. Real-time measurement of aerosol particle concentration at high temperatures; Hiukkaspitoisuuden reaaliaikainen mittaaminen korkeassa laempoetilassa

    Energy Technology Data Exchange (ETDEWEB)

    Keskinen, J.; Hautanen, J.; Laitinen, A. [Tampere Univ. of Technology (Finland). Physics

    1997-10-01

    The aim of this project is to develop a new method for continuous aerosol particle concentration measurement at elevated temperatures (up to 800-1000 deg C). The measured property of the aerosol particles is the so called Fuchs surface area. This quantity is relevant for diffusion limited mass transfer to particles. The principle of the method is as follows. First, aerosol particles are charged electrically by diffusion charging process. The charging takes place at high temperature. After the charging, aerosol is diluted and cooled. Finally, aerosol particles are collected and the total charge carried by the aerosol particles is measured. Particle collection and charge measurement take place at low temperature. Benefits of this measurement method are: particles are charged in-situ, charge of the particles is not affected by the temperature and pressure changes after sampling, particle collection and charge measurement are carried out outside the process conditions, and the measured quantity is well defined. The results of this study can be used when the formation of the fly ash particles is studied. Another field of applications is the study and the development of gasification processes. Possibly, the method can also be used for the monitoring the operation of the high temperature particle collection devices. (orig.)

  15. A strategy for urban outdoor production of high-concentration algal biomass for green biorefining.

    Science.gov (United States)

    Lim, Chun Yong; Chen, Chia-Lung; Wang, Jing-Yuan

    2013-05-01

    The present study was to investigate the feasibility of carrying out effective microalgae cultivation and high-rate tertiary wastewater treatment simultaneously in a vertical sequencing batch photobioreactor with small areal footprint, suitable for sustainable urban microalgae production. For 15 consecutive days, Chlorella sorokiniana was cultivated in synthetic wastewater under various trophic conditions. A cycle of 12-h heterotrophic: 12-h mixotrophic condition produced 0.98 g l(-1) d(-1) of algal biomass in tandem with a 94.7% removal of 254.4 mg l(-1) C-acetate, a 100% removal of 84.7 mg l(-1) N-NH4 and a removal of 15.0 mg l(-1) P-PO4. The cells were harvested via cost-effective chitosan flocculation with multiple dosing (3 times) applying established chitosan:cell ratio (1:300 w/w) and pH control (6.3-6.8). Reproducible flocculation efficiencies of greater than 99% and high-concentration algal broths (>20% solids) were achieved. PMID:23186659

  16. Implantation of high concentration noble gases in cubic zirconia and silicon carbide: A contrasted radiation tolerance

    Science.gov (United States)

    Veli?a, Gihan; Debelle, Aurélien; Thomé, Lionel; Mylonas, Stamatis; Vincent, Laetitia; Boulle, Alexandre; Jagielski, Jacek; Pantelica, Dan

    2014-08-01

    The modifications of the microstructure of yttria-stabilized cubic zirconia and silicon carbide single crystals implanted with high concentrations of noble gas ions and subsequently annealed at high temperature were characterized using RBS/C, XRD and TEM. It is found that the annealing behavior is strongly dependent on both the material and the implanted noble gases. Ar-implanted yttria-stabilized zirconia shows no significant microstructural modification upon annealing at 800 °C, e.g. dislocations are still present and the size of the Ar bubbles does not evolve. This is in strong contrast with previous observations on helium-implanted zirconia, where the formation of bubbles and elongated fractures were observed. In the case of SiC, thermal annealing at 1000 °C shows an enhanced damage recovery when He is implanted as compared to Ar implantation and the recrystallization of the matrix is accompanied with the release of noble gas atoms. This difference can be ascribed to different atomic radii, and thus mobility of implanted species.

  17. GaInN quantum wells with high indium concentrations on polar and nonpolar surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Joenen, Holger; Langer, Torsten; Draeger, Daniel; Hoffmann, Lars; Bremers, Heiko; Rossow, Uwe; Hangleiter, Andreas [Institut fuer Angewandte Physik, TU Braunschweig (Germany); Metzner, Sebastian; Bertram, Frank; Christen, Juergen [Institut fuer Experimentelle Physik, Otto-von-Guericke-Universitaet, Magdeburg (Germany)

    2009-07-01

    The strong decrease of the internal quantum efficiency (IQE) of GaN based light emitters towards the green spectral region is a well known problem. Beside a degrading material quality the stronger piezoelectric field with increasing indium content reduces the quantum efficiency. A promising way to solve this problem is to grow on non-polar surfaces such as the (1 anti 100) of the wurtzite crystal structure. In this case there is no field in growth direction and therefore devices might be more efficient. However, growth conditions may significantly differ from those on conventional c-plane surfaces. In this contribution we discuss the indium incorporation in c-plane and m-plane GaInN quantum wells. Our samples were grown by low pressure MOVPE and characterized by SEM, XRD, CL and PL measurements. The In content of GaInN layers increases with decreasing growth temperature and seems to be comparable for both surfaces under same growth conditions. However, for high In concentrations above 30% possible relaxation and a degradation of the quantum wells during high temperature growth steps become critical issues.

  18. GaInN quantum wells with high indium concentrations on polar and nonpolar surfaces

    International Nuclear Information System (INIS)

    The strong decrease of the internal quantum efficiency (IQE) of GaN based light emitters towards the green spectral region is a well known problem. Beside a degrading material quality the stronger piezoelectric field with increasing indium content reduces the quantum efficiency. A promising way to solve this problem is to grow on non-polar surfaces such as the (1 anti 100) of the wurtzite crystal structure. In this case there is no field in growth direction and therefore devices might be more efficient. However, growth conditions may significantly differ from those on conventional c-plane surfaces. In this contribution we discuss the indium incorporation in c-plane and m-plane GaInN quantum wells. Our samples were grown by low pressure MOVPE and characterized by SEM, XRD, CL and PL measurements. The In content of GaInN layers increases with decreasing growth temperature and seems to be comparable for both surfaces under same growth conditions. However, for high In concentrations above 30% possible relaxation and a degradation of the quantum wells during high temperature growth steps become critical issues.

  19. Effects of high glucose concentrations on the endothelial function of the renal microcirculation of rabbits

    Scientific Electronic Library Online (English)

    Filipe de Souza, Affonso; Solange, Cailleaux; Leonardo Felipe Corrêa, Pinto; Marília de Brito, Gomes; Eduardo, Tibiriçá.

    2003-08-01

    Full Text Available OBJECTIVE: To assess the acute effects of high glucose concentrations on vascular reactivity in the isolated non diabetic rabbit kidney. METHODS: Rabbits were anaesthetized for isolation of the kidneys. Renal arteries and veins were cannulated for perfusion with Krebs-Henselleit solution and measure [...] ment of perfusion pressure. After 3 hours of perfusion with glucose 5,5 mM (control ) and 15 mM, the circulation was submitted to sub maximal precontraction (80% of maximal response) trough continuous infusion of noradrenaline 10 mM. Vascular reactivity was then assessed trough dose-responses curves with endothelium-dependent (acetylcholine) and independent (sodium nitroprusside) vasodilators. The influence of hyperosmolarity was analyzed with perfusion with mannitol 15mM. RESULTS: A significant reduction in the endothelium-dependent vasodilation in glucose 15mM group was observed compared to that in control, but there was no difference in endothelium-independent vasodilation. After perfusion with mannitol 15 mM, a less expressive reduction in endothelium-dependent vasodilation was observed, only reaching significance in regard to the greatest dose of acetylcholine. CONCLUSION: High levels of glucose similar to those found in diabetic patients in the postprandial period can cause significant acute changes in renal vascular reactivity rabbits. In diabetic patients these effects may also occur and contribute to diabetes vascular disease.

  20. Implantation of high concentration noble gases in cubic zirconia and silicon carbide: A contrasted radiation tolerance

    International Nuclear Information System (INIS)

    The modifications of the microstructure of yttria-stabilized cubic zirconia and silicon carbide single crystals implanted with high concentrations of noble gas ions and subsequently annealed at high temperature were characterized using RBS/C, XRD and TEM. It is found that the annealing behavior is strongly dependent on both the material and the implanted noble gases. Ar-implanted yttria-stabilized zirconia shows no significant microstructural modification upon annealing at 800 °C, e.g. dislocations are still present and the size of the Ar bubbles does not evolve. This is in strong contrast with previous observations on helium-implanted zirconia, where the formation of bubbles and elongated fractures were observed. In the case of SiC, thermal annealing at 1000 °C shows an enhanced damage recovery when He is implanted as compared to Ar implantation and the recrystallization of the matrix is accompanied with the release of noble gas atoms. This difference can be ascribed to different atomic radii, and thus mobility of implanted species

  1. High Concentration of Zinc in Sub-retinal Pigment Epithelial Deposits

    International Nuclear Information System (INIS)

    One of the hallmarks of age-related macular degeneration (AMD), the leading cause of blindness in the elderly in Western societies, is the accumulation of sub-retinal pigment epithelial deposits (sub-RPE deposits), including drusen and basal laminar deposits, in Bruch's membrane (BM). The nature and the underlying mechanisms of this deposit formation are not fully understood. Because we know that zinc contributes to deposit formation in neurodegenerative diseases, we tested the hypothesis that zinc might be involved in deposit formation in AMD. Using zinc specific fluorescent probes and microprobe synchrotron X-ray fluorescence we showed that sub-RPE deposits in post-mortem human tissues contain unexpectedly high concentrations of zinc, including abundant bio-available (ionic and/or loosely protein bound) ions. Zinc accumulation was especially high in the maculae of eyes with AMD. Internal deposit structures are especially enriched in bio-available zinc. Based on the evidence provided here we suggest that zinc plays a role in sub-RPE deposit formation in the aging human eye and possibly also in the development and/or progression of AMD

  2. Improvement in mechanical properties of high concentration particle doped thermoset composites

    International Nuclear Information System (INIS)

    The paper relates to high concentration particle doped composites based on thermosetting polymer systems in which the sequential addition of particles of certain size distribution is followed by curing and casting of the slurry to form a thermoset composite. Conventionally, at a threshold of beyond 90% of particles by weight of the polymer using triglyceride, the mechanical properties of the composite exhibit a sharp decline. The present research mitigates this behavior by incorporating a unique combination of cross-linking agents in the base polymer to impart exceptional mechanical properties to the composite. More specifically, the base polymer consists of butadiene, with triglyceride as cross-linking agent together with hydroxy-alkane as the chain extension precursors, when tune to the appropriate level of hard segment ratio in the polymer. An added advantage according to the present work resides in the analytical nature of butadiene pre-polymer as opposed to natural product; traditional composites based on natural sources are hampered by their inconsistent chemical composition and poor shelf life in the fabricated composite. The thermoset composite according the present research exhibits superior tensile strength (200-300 psi) properties using particle loading as high as 92% by weight of the fabricated composite as measured on a Tinius Olsen machine. Dynamic Mechanical Testing reveals interesting combination of storage and loss moduli in the fabricated specimens a loss moduli in the fabricated specimens as a function of optimizing the thermal response of the viscoelastic composite to imposed vibration loading. (author)

  3. Seasonal variation in phosphorus concentration-discharge hysteresis inferred from high-frequency in situ monitoring

    Science.gov (United States)

    Bieroza, M. Z.; Heathwaite, A. L.

    2015-05-01

    High-resolution in situ total phosphorus (TP), total reactive phosphorus (TRP) and turbidity (TURB) time series are presented for a groundwater-dominated agricultural catchment. Meta-analysis of concentration-discharge (c-q) intra-storm signatures for 61 storm events revealed dominant hysteretic patterns with similar frequency of anti-clockwise and clockwise responses; different determinands (TP, TRP, TURB) behaved similarly. We found that the c-q loop direction is controlled by seasonally variable flow discharge and temperature whereas the magnitude is controlled by antecedent rainfall. Anti-clockwise storm events showed lower flow discharge and higher temperature compared to clockwise events. Hydrological controls were more important for clockwise events and TP and TURB responses, whereas in-stream biogeochemical controls were important for anti-clockwise storm events and TRP responses. Based on the best predictors of the direction of the hysteresis loops, we calibrated and validated a simple fuzzy logic inference model (FIS) to determine likely direction of the c-q responses. We show that seasonal and inter-storm succession in clockwise and anti-clockwise responses corroborates the transition in P transport from a chemostatic to an episodic regime. Our work delivers new insights for the evidence base on the complexity of phosphorus dynamics. We show the critical value of high-frequency in situ observations in advancing understanding of freshwater biogeochemical processes.

  4. NIOSH (National Institute for Occupational Safety and Health) testimony to DOL (Department of Labor) on OSHA (Occupational Safety and Health Administration) proposed rule for occupational exposure to benzene, by R. Lemen, March 20, 1986

    International Nuclear Information System (INIS)

    The testimony reviewed the history of benzene exposure and the development of recommended exposure limits. Data were reviewed on pharmacokinetics, cytotoxicity, long- and short-term exposures, and skin absorption of benzene. Benzene or its metabolites have been shown to remain in the body for a long period of time following inhalation exposure. Studies in mice revealed exposure-related increases in the frequency of sister chromatid exchanges and micronuclei at all exposure concentrations. Some epidemiological standards relating to the benzene standard were cited. NIOSH recommended that the Permissible Exposure Limit for benzene be reduced to 0.1 ppm as an 8-hour time-weighted average, and that there be a limit on short-term exposures of 1.0ppm for any 15-minute period. These recommendations were made to protect against inhalation of benzene and did not relate to skin absorption. Reports indicated that significant benzene absorption can result among workers exposed to solvents containing about 0.5 percent benzene. It was recommended that steps be taken to eliminate this route of exposure. The use of pressure-demand supplied air respirators with an auxiliary self-contained breathing apparatus or a pressure-demand apparatus was recommended

  5. The effect of benzene on serum hormones and the activity of some enzymes in different tissues of rats

    Directory of Open Access Journals (Sweden)

    Dere Egemen D.

    2003-01-01

    Full Text Available The effects of a 100 mg.kg -1 dose of benzene, an occupational and environmental toxicant, were investigated on serum, estradiol and testosterone concentrations as well as lactate dehydrogenase (LDH, alkaline phosphatase (ALP, alanine amino transferase (ALT, aspartate amino transferase (AST, and pyruvate kinase (PK activities in the liver and kidney of rats after 2, 4, 8, 16, 32, 64 and 72 hours. Benzene was given intraperitoneally to Rat rattus norvegicus and the control groups were injected with physiological saline. Liver tissue LDH, AST, ALT and kidney tissue LDH, ALP, AST, ALT activities were lower in the benzene treated group when compared to those in the control group (p<0.05. A tendency for an increase in the liver tissue ALP activity was observed, which was significant at 8 and 16 hours (p<0.05. There were significant increases in ALT in the liver and LDH, AST, and ALT enzyme activities in the kidney tissue at the beginning of the experiment in both groups and these activities were found to be nearly the same. Pyruvate kinase enzyme activities in rats given benzene were slightly increased in kidney tissues but lower in liver tissues. Differences between the groups tended to disappear towards the end of the experimental period. However, serum estradiol concentrations in the serum diverged significantly (p<0.05. Consequently, it was found that benzene administration led to some changes (increases then decreases in LDH, ALP, ALT, AST, and PK activity and estradiol, testosterone concentrations in different tissues of rats. Possible causes of the increases and decreases in enzyme activities and hormone levels are discussed.

  6. High-throughput automatic flow method for determination of trace concentrations of aluminum in dialysis concentrate solutions using salicylaldehyde picolinoylhydrazone as a turn-on fluorescent probe.

    Science.gov (United States)

    Garau, Arnau; Oliver, Miquel; Rosende, María; Mánuel-Vez, Manuel P; Miró, Manuel

    2015-02-01

    A simple and expedient flow-based assembly capitalizing on programmable flow is herein proposed for reliable determination of trace level concentrations of aluminum as a potential contaminant in dialysis concentrate solutions without any prior sample clean-up/preconcentration procedure. Using salicylaldehyde picolinoylhydrazone in weakly acidic media as a turn-on fluorescent probe, the manifold is devised to handle three samples concurrently in stopped-flow reaction mode for simultaneous improvement of the analytical sensitivity and sample throughput. Analytical parameters influencing the sensitivity and repeatability of the assays, namely, probe concentration, reaction temperature and reaction time were investigated using a multivariate optimization protocol composed of a full factorial screening design followed by a Doehlert matrix model. The analysis of the Pareto chart and surface response revealed that the reaction time and amount of fluorescent probe were critical parameters for reliable assays of aluminum at the low ng mL(-1) level. Under the optimized chemical and physical variables, a detection limit of 1.1ngmL(-1) Al(III) at the 3s(blank) level, relative standard deviations better than 1.0%, a dynamic linear range of 5.0-80 ng mL(-1) and a sample throughput up to 25 h(-1) were obtained with no need for either sample preconcentration or the use of organized supramolecular systems. Demonstrated with the analysis of hemodialysis and peritoneal concentrate solutions, and dialysis waters, the flow-through method copes with the requirements of regulatory bodies (e.g., European Pharmacopeia) for quality control of aluminum in high salinity containing dialysis concentrates. PMID:25435237

  7. Mangiferin binding to serum albumin is non-saturable and induces conformational changes at high concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Freitas, P.G.; Barbosa, A.F. [Biochemistry Laboratory, Institute of Exact Sciences, Federal University of Alfenas, Unifal-MG, R. Gabriel Monteiro da Silva, 700, 37130-000 Alfenas, MG (Brazil); Saraiva, L.A. [Phytochemistry and Medicinal Chemistry Laboratory, Institute of Exact Sciences, Unifal-MG (Brazil); Camps, I. [Physics Laboratory, Institute of Exact Sciences, Unifal-MG (Brazil); Silveira, N.J.F. da [Bioinformatics Laboratory, Institute of Exact Sciences, Unifal-MG (Brazil); Veloso, M.P. [Phytochemistry and Medicinal Chemistry Laboratory, Institute of Exact Sciences, Unifal-MG (Brazil); Santos, M.H., E-mail: poliany.santos@gmail.com [Phytochemistry and Medicinal Chemistry Laboratory, Institute of Exact Sciences, Unifal-MG (Brazil); Schneedorf, J.M., E-mail: zemasfs@gmail.com [Biochemistry Laboratory, Institute of Exact Sciences, Federal University of Alfenas, Unifal-MG, R. Gabriel Monteiro da Silva, 700, 37130-000 Alfenas, MG (Brazil)

    2012-11-15

    The binding interaction between mangiferin (MGF), which a natural xanthone isolated from mangoes, and bovine serum albumin (BSA) was studied with absorbance and fluorescence spectroscopy, cyclic voltammetry and molecular modeling. The data were analyzed to assess the binding mechanism, effect of pH and ionic strength, conformational changes in the protein and electrical charge transfer involved. The MGF-BSA complex exhibited positive cooperativity with a 1:1 stoichiometry (K{sub d}=0.38 mmol L{sup -1}) for the first binding site and a non-saturable binding at high ligand concentrations. Furthermore, the data also suggest an increase in drug bioavailability in the acidic region and relatively low ionic strength values, which are close to physiological levels. The data suggest a specific electrostatic interaction together with hydrophobic effects and H-bonding displayed in MGF binding to the BSA IIA subdomain. Synchronous fluorescence spectra indicate that there are conformational changes in the polypeptide backbone upon ligand binding. Cyclic voltammetry indicates that there is an irreversible charge transfer between MGF and BSA that is modulated by diffusion on the electrode surface, where two electrons are transferred. These results can help the knowledge of the pharmacokinetic activities of natural or chemical xanthone-based drugs. - Highlights: Black-Right-Pointing-Pointer The MGF-BSA complex exhibited positive cooperativity beyond 1:1 stoichiometry. Black-Right-Pointing-Pointer The interaction of MGF with BSA is non-saturable at higher ligand concentration. Black-Right-Pointing-Pointer The binding was accomplished by H-bonding, hydrophobic and electrostatic forces. Black-Right-Pointing-Pointer The apparent binding constant for MGF-BSA was 0.38 mmol L{sup -1}. Black-Right-Pointing-Pointer MGF binds electrostatically to BSA, different from a hydrophobic interaction to HSA.

  8. The Character of Dual Site Adsorbent on Coal Fly Ash Toward Benzene Adsorption

    Directory of Open Access Journals (Sweden)

    Widi Astuti

    2014-10-01

    Full Text Available Large quantities of coal fly ash (CFA are produced during combustion of coal in the production of electricity. Most of this ash has not been widely used. CFA is mainly composed of some oxides including Al2O3 and SiO2 having active site and unburnedcarbon as a mesopore that enables it to act as a dual site adsorbent. To get different characters of dual site, CFA was sieved using 150 mesh size, heated at 400oC and reactedwith sodium hydroxide solution. Furthermore, CFA was used as adsorbent of benzene in aqueous solutions. Equilibrium data were evaluated by single site and dual site isotherm models. It can be concluded that single site model yielded excellent fit with equilibrium data of benzene. The values of maximum concentration of adsorbate in solid surface (C?m and Langmuir constant (KL are affected by [Si+Al]/C ratio in CFA. The increase of [Si+Al]/C ratio causes a decrease of qm and KL values.Keywords : coal fly ash, adsorption, benzene

  9. Treatment of marine sewage pumpout and RV park pumpout wastewater containing high strength concentrations of formaldehyde

    International Nuclear Information System (INIS)

    'Full text:' A consortium of companies has developed an integrated 'on-site' wastewater treatment technology that is capable of handling and degrading RV Park and Marine Sewage Pumpout Wastes which contain formaldehyde [35 - 80 mg/L]. Boat and RV owners add formaldehyde to their toilets to eliminate odors. When these materials are pumped out they are high in solids content and have high concentrations of HCHO, which makes them difficult to degrade at POTWs. At the heart of this process is 1. An aeration tank with a Venturi Aerator totally external to the tank and 2. The addition of a blend of cultured bacteria that have selected for their ability to degrade formaldehyde. For a complete 'on-site' treatment system Bioclere Trickling Filters can follow this aeration/bacterial treatment system. This is an ideal system configuration for remote locations (RV Parks) or for fresh water lake Marinas looking to reduce their disposal costs and for groundwater discharge with no adverse effect on water quality. Until the development of the formaldehyde degrading bacteria for an industrial wastewater process there were no cultures commercially available specifically for degrading formaldehyde. The most commonly used bacteria were pseudomonas strains for carbohydrate or hydrocarbon wastewater extracted from activated sludge plants. And since formaldehyde is infinitely soluble in a liquid it is difficult to degrade or mineralize. The process in an activated sludge WWTP plant took ovein an activated sludge WWTP plant took over 72 hours. With the newly selected consortia of cultures, HCHO can be degraded in 12-14 hours on a batch basis. This is accomplished in a uniquely configured aeration tank where the 'environment' of the tank is constantly conditioned by a Venturi Aerator which strips carbon dioxide generated by the aerobes to maintain a neutral pH, and provide high levels of DO (>5.0 mg/L) to keep the process aerobic. (author)

  10. Preparation and Characterization of Copolymer of Benzene and Perylene Photoluminescence Organic Material

    Directory of Open Access Journals (Sweden)

    Shelly Sachdeva

    2010-09-01

    Full Text Available OLED organic light emitting diode intended primarily as picture elements in practical display devices. In the present study an organic material which is a copolymer of benzene and Perylene was synthesised and characterized by Electroluminescence spectra (EL, Current Voltage (I-V, UV-Vis absorption spectra and Thermogravimetric Analysis (TGA . The result of device characterized by ITO/BPery /Al layered diode, layered was found highly effective for application of this as electroluminescence material.

  11. Infrared emission from photo-excited gaseous benzene: detection with a new home-made spectrometer

    Science.gov (United States)

    Féraud, G.; Carpentier, Y.; Pino, T.; Longval, Y.; Dartois, E.; Chamaillé, T.; Vasquez, R.; Vincent, J.; Parneix, P.; Falvo, C.; Bréchignac, Ph.

    2012-02-01

    The infrared fluorescence decay and the dispersed emission spectrum are presented for gaseous benzene following 193 nm laser excitation. They were measured with FIREFLY (Fluorescence in the InfraRed from Excited FLYing molecules), a new home-made spectrometer. Redshift and redtail in the CH stretch emission spectra (3.3 ?m region) demonstrate that anharmonicity plays a key role when dealing with high internal energies, as it is the case in the interstellar medium.

  12. ASPEN HYSYS SIMULATION AND COMPARISON BETWEEN ORGANIC SOLVENTS (SULFOLANE AND DMSO) USED FOR BENZENE EXTRACTION

    OpenAIRE

    Zaiz, T.; Lanez, H.; Kechida, B.

    2013-01-01

    Due to the high increase of the production of aromatic hydrocarbons: benzene, toluene and xylenes BTX from oil because of the large activity of their big markets especially with the availability of great quantities of these aromatic fractions in the oil. This study has two main parts the first presents a general vision of the aromatic hydrocarbons, the second is going to focus on the liquid-liquid extraction with the selected solvents as a separation method. The solvent selection depends on m...

  13. Preparation and Characterization of Copolymer of Benzene and Perylene Photoluminescence Organic Material

    OpenAIRE

    Shelly Sachdeva; Atul Kumar,

    2010-01-01

    OLED organic light emitting diode intended primarily as picture elements in practical display devices. In the present study an organic material which is a copolymer of benzene and Perylene was synthesised and characterized by Electroluminescence spectra (EL), Current Voltage (I-V), UV-Vis absorption spectra and Thermogravimetric Analysis (TGA ). The result of device characterized by ITO/BPery /Al layered diode, layered was found highly effective for application of this as electroluminescence ...

  14. Hybrid Separation and Detection Device for Analysis of Benzene, Toluene, Ethylbenzene, and Xylenes in Complex Samples

    OpenAIRE

    Iglesias, Rodrigo A.; Tsow, Francis; Wang, Rui; Erica S. Forzani; Tao, Nongjian

    2009-01-01

    We present a hybrid system for rapid detection and analysis of benzene, toluene, ethylbenzene, and xylenes (BTEX). The system combines selective and sensitive sensing elements with a fast and miniaturized chromatographic separation method. The sensing elements are an array of microfabricated quartz crystal tuning forks modified with selective molecularly imprinted polymers, and the separation method uses optimized short columns. The high sensitivity and selectivity of the sensing elements tog...

  15. Tri-Lateral Noor al Salaam High Concentration Solar Central Receiver Program

    Energy Technology Data Exchange (ETDEWEB)

    Blackmon, James B

    2008-03-31

    This report documents the efforts conducted primarily under the Noor al Salaam (“Light of Peace”) program under DOE GRANT NUMBER DE-FC36-02GO12030, together with relevant technical results from a closely related technology development effort, the U.S./Israel Science and Technology Foundation (USISTF) High Concentration Solar Central Receiver program. These efforts involved preliminary design, development, and test of selected prototype power production subsystems and documentation of an initial version of the system definition for a high concentration solar hybrid/gas electrical power plant to be built in Zaafarana, Egypt as a first step in planned commercialization. A major part of the planned work was halted in 2007 with an amendment in October 2007 requiring that we complete the technical effort by December 31, 2007 and provide a final report to DOE within the following 90 days. This document summarizes the work conducted. The USISTF program was a 50/50 cost-shared program supported by the Department of Commerce through the U.S./Israel Science and Technology Commission (USISTC). The USISTC was cooperatively developed by President Clinton and the late Prime Minister Rabin of Israel "to encourage technological collaboration" and "support peace in the Middle East through economic development". The program was conducted as a follow-on effort to Israel's Magnet/CONSOLAR Program, which was an advanced development effort to design, fabricate, and test a solar central receiver and secondary optics for a "beam down" central receiver concept. The status of these hardware development programs is reviewed, since they form the basis for the Noor al Salaam program. Descriptions are provided of the integrated system and the major subsystems, including the heliostat, the high temperature air receiver, the power conversion unit, tower and tower reflector, compound parabolic concentrator, and the master control system. One objective of the USISTF program was to conduct marketing research, identify opportunities for use of this technology, and to the extent possible, secure an agreement leading to a pre-commercialization demonstration or prototype plant. This was accomplished with the agreement to conduct the Noor al Salaam program as a tri-lateral project between Egypt, Israel, and the U.S. The tri-lateral project was led by the University of Alabama in Huntsville (UAH); this included the Egyptian New and Renewable Energy Authority and the Israeli USISTC participants. This project, known was Noor al Salaam, was funded by the U.S. Agency for International Development (USAID) through the Department of Energy (DOE). The Egyptian activity was under the auspices of the Egyptian Ministry of Energy and Electricity, New and Renewable Energy Authority (NREA) as part of Egypt's plans for renewable energy development. The objective of the Noor al Salaam project was to develop the conditions necessary to obtain funding and construct and operate an approximately 10 to 20 Megawatt hybrid solar/natural gas demonstration power plant in Zaafarana, Egypt that could serve both as a test bed for advanced solar technology evaluations, and as a forerunner to commercial plant designs. This plant, termed Noor Al Salaam, or “Light of Peace”, reached the initial phase of system definition before being curtailed, in part by changes in USAID objectives, coupled with various delays that were beyond the scope of the program to resolve. The background of the USISTF technology development and pre-commercialization effort is provided in this report, together with documentation of the technology developments conducted under the Noor al Salaam program. It should be noted that only a relatively small part of the Noor al Salaam funding was expended over the approximately five years for which UAH was prime contractor before the program was ordered closed (Reference 1) so that the remaining funds could be returned to USAID.

  16. 40 CFR 80.1270 - Who may generate benzene credits under the ABT program?

    Science.gov (United States)

    2010-07-01

    ...Early benzene credits. Early benzene credits are credits generated...it owns that has an approved benzene baseline under § 80.1285...of this section must process crude oil and/or intermediate...processing units. (iii) Early benzene credits shall be...

  17. Concentration Waves in High-Entropy Alloys - a new alloy design approach

    Science.gov (United States)

    Singh, Prashant; Johnson, Duane D.

    2015-03-01

    Chemical short-range order (SRO) in solid solutions can be interpreted as a ``concentration wave'' - a Fourier decomposition of nascent order - identified experimentally via Warren-Cowley SRO parameters. We present a rigorous thermodynamic theory to predict and uniquely interpret the SRO in N -component alloys. Based on KKR-CPA electronic structure, we implemented this method using thermodynamic linear-response to include all alloying effects, e.g., band-filling, hybridization, Fermi -surface nesting and van Hove instabilities. We apply this first-principles method to high-entropy alloys (HEAs), i.e., solid solutions with N >4 that inhibit small-cell order due to large entropy competing against ordering enthalpy, as their properties are sensitive to SRO. We validated theory with comparison to experiments in A2 Nb-Al-Ti and A1 Cu-Ni-Zn . We then predict and analyze SRO and mechanical trends in Ni-Ti-Zr-Cu-Al and Co-Cr-Fe-Mn-Ni systems - showcasing this new first-principles-based alloy design method. Chemical short-range order (SRO) in solid solutions can be interpreted as a ``concentration wave'' - a Fourier decomposition of nascent order - identified experimentally via Warren-Cowley SRO parameters. We present a rigorous thermodynamic theory to predict and uniquely interpret the SRO in N -component alloys. Based on KKR-CPA electronic structure, we implemented this method using thermodynamic linear-response to include all alloying effects, e.g., band-filling, hybridization, Fermi -surface nesting and van Hove instabilities. We apply this first-principles method to high-entropy alloys (HEAs), i.e., solid solutions with N >4 that inhibit small-cell order due to large entropy competing against ordering enthalpy, as their properties are sensitive to SRO. We validated theory with comparison to experiments in A2 Nb-Al-Ti and A1 Cu-Ni-Zn . We then predict and analyze SRO and mechanical trends in Ni-Ti-Zr-Cu-Al and Co-Cr-Fe-Mn-Ni systems - showcasing this new first-principles-based alloy design method. Work was supported by the USDoE, Office of Sci., Basic Energy Sci., Materials Sci. and Eng. Division for `Materials Discovery.' Research was performed at Ames Lab, operated by Iowa State University under Contract #DE-AC02-07CH11358.

  18. Increasing dietary neutral detergent fiber concentration decreases ruminal hydrogen sulfide concentrations in steers fed high-sulfur diets based on ethanol coproducts.

    Science.gov (United States)

    Morine, S J; Drewnoski, M E; Hansen, S L

    2014-07-01

    Cattle feedlot diets commonly contain ethanol coproducts that are high in S. This dietary S is reduced in the rumen by sulfate reducing bacteria, resulting in an accumulation of hydrogen sulfide (H2S), increasing the risk for S toxicity. A negative correlation between H2S and ruminal pH has been observed previously. The objective of this study was to determine the effect of varying dietary NDF from chopped bromegrass hay (66% NDF) on performance, rum