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1

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

UK PubMed Central (United Kingdom)

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

Karimi A; Golbabaei F; Neghab M; Pourmand MR; Nikpey A; Mohammad K; Mehrnia MR

2013-01-01

2

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

Directory of Open Access Journals (Sweden)

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.

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

2013-01-01

3

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

Directory of Open Access Journals (Sweden)

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

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

2013-01-01

4

3-(3,4-Dihydroxyphenyl)adenine, a urinary DNA adduct formed in mice exposed to high concentrations of benzene.  

UK PubMed Central (United Kingdom)

Metabolism of benzene, an important environmental and industrial carcinogen, produces three electrophilic intermediates, namely, benzene oxide and 1,2- and 1,4-benzoquinone, capable of reacting with the DNA. Numerous DNA adducts formed by these metabolites in vitro have been reported in the literature, but only one of them was hitherto identified in vivo. In a search for urinary DNA adducts, specific LC-ESI-MS methods have been developed for the determination in urine of six nucleobase adducts, namely, 7-phenylguanine, 3-phenyladenine, 3-hydroxy-3,N(4) -benzethenocytosine, N(2) -(4-hydroxyphenyl)guanine, 7-(3,4-dihydroxyphenyl)guanine and 3-(3,4-dihydroxyphenyl)-adenine (DHPA), with detection limits of 200, 10, 260, 50, 400 and 200?pg?ml(-1) , respectively. Mice were exposed to benzene vapors at concentrations of 900 and 1800?mg?m(-3) , 6?h per day for 15 consecutive days. The only adduct detected in their urine was DHPA. It was found in eight out of 30 urine samples from the high-exposure group at concentrations of 352 ± 146?pg?ml(-1) (mean ± SD; n?=?8), whereas urines from the low-exposure group were negative. Assuming the DHPA concentration in the negative samples to be half of the detection limit, conversion of benzene to DHPA was estimated to 2.2?×?10(-6) % of the absorbed dose. Thus, despite the known high mutagenic and carcinogenic potential of benzene, only traces of a single DNA adduct in urine were detected. In conclusion, DHPA is an easily depurinating adduct, thus allowing indication of only high recent exposure to benzene, but not long-term damage to DNA in tissues.

Mikeš P; Sístek V; Krouželka J; Králík A; Frantík E; Mráz J; Linhart I

2013-06-01

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

UK PubMed Central (United Kingdom)

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

Nordtug T; Børseth JF; Olsen A; Zachariassen KE

1991-01-01

6

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

Science.gov (United States)

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

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

1991-01-01

7

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

Science.gov (United States)

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

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

2013-04-01

8

A method for producing high octane benzene  

Energy Technology Data Exchange (ETDEWEB)

The method for producing high octane benzene, which involves the multi-stage catalytic reformation of benzene fractions at a higher temperature and pressure, is improved by subjecting the reformation products to rectification before the final stage, producing a primary fraction with a final boiling temperature of 105-120 degrees and a settling fraction; the settling fraction is given the last injections at the final reformation stage, and the products are mixed with the primary fraction in order to increase the yield and quality of benzene.

Akhmetov, A.F.; Ivanov, A.F.; Tanatarov, M.A.

1982-01-01

9

A method for producing high octane benzene  

Energy Technology Data Exchange (ETDEWEB)

The method for producing high octane benzene, which involves catalytically reforming straight-run benzene fractions, performed in the presence of Pt/A1/sub 2/O/sub 3/ catalyst, and which includes rectifying the fluid reformation products before the final stage, producing the primary and settling fractions, injecting the settling fraction for the last reforming stage and mixing the fraction which has an initial boiling point of 85-104 degrees in order to improve the quality of the target product.

Tanatarov, M.A.; Akhmetov, A.F.; Kiladze, G.K.

1982-01-01

10

Applicability of urinary benzene to biological monitoring of occupational and environmental exposure to very low benzene concentrations.  

UK PubMed Central (United Kingdom)

OBJECTIVE: To verify whether urinary benzene is an applicable biomarker of occupational exposure to very low concentrations of benzene, considering the influence of cigarette smoke and benzene-toluene co-exposure. MATERIALS AND METHODS: 23 filling station attendants with occupational exposure to benzene and 31 controls were analyzed. Occupational and environmental exposure was monitored and t,t-muconic acid (t,t-MA), S-phenylmercapturic acid (SPMA), urinary benzene and creatinine in the urine samples were tested. RESULTS: Occupational exposure to benzene and toluene was significantly higher in the filling station attendants than in the controls, whereas t,t-MA, SPMA and urinary benzene were not different in the two groups. Instead, the smoker group showed significantly higher values for the above biomarkers than the non-smoker group, each of which included both exposed workers and controls. SPMA was dependent on airborne benzene and cigarette smoking, and urinary benzene only on cigarette smoking, while t,t-MA was not dependent on either of these variables. CONCLUSIONS: At very low concentrations of occupational exposure to benzene, urinary benzene is less valid than SPMA as a biomarker, even if both are strongly influenced by smoking habit. Abstention from smoking should therefore be recommended for at least two hours before urine collection.

Lovreglio P; Carrieri M; Barbieri A; Sabatini L; Fracasso ME; Doria D; Iavicoli S; Drago I; D'errico MN; Imbriani M; Violante FS; Bartolucci GB; Soleo L

2011-01-01

11

A method for producing high octane benzene  

Energy Technology Data Exchange (ETDEWEB)

The method for producing high octane benzene, which involves reforming straight-run benzene fractions in the presence of an alumoplatinum catalyst at 480-530 degrees, up to 40 atmospheres of pressure, and with the final rectification of stable reformation products which produces the primary fraction from an end boiling point of 120 degrees and lower and the secondary fraction from the initial boiling point temperature of 120 degrees and higher, is improved by exposing the fraction to the alumoplatinum catalyst at a higher temperature and pressure and mixing the exposed products with the secondary fraction in order to improve the quality of the benzene. Preferably, the exposure is conducted at 200-450 degrees and with 20-25 atmospheres of pressure. Exposing the fraction with the final temperature point of 120 degrees and lower to the alumoplatinum catalyst is conducted preferably with a volumetric rate of raw material injection at 0.5-5.0 hours; the circulation of H/sub 2/-containing gas is 200-800 HM/sup 3//M/sup 3/.

Akhmetov, A.F.; Khuramshin, T.Z.; Kiladze, T.K.; Makhov, A.F.; Risov, B.Ia.; Smiriov, N.P.; Tanatarov, M.A.; Teliashev, G.G.

1982-01-01

12

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.)

2004-01-01

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Evaluation of exposure biomarkers in offshore workers exposed to low benzene and toluene concentrations.  

UK PubMed Central (United Kingdom)

PURPOSE: Characterize ethylbenzene and xylene air concentrations, and explore the biological exposure markers (urinary t,t-muconic acid (t,t-MA) and unmetabolized toluene) among petroleum workers offshore. Offshore workers have increased health risks due to simultaneous exposures to several hydrocarbons present in crude oil. We discuss the pooled benzene exposure results from our previous and current studies and possible co-exposure interactions. METHODS: BTEX air concentrations were measured during three consecutive 12-h work shifts among 10 tank workers, 15 process operators, and 18 controls. Biological samples were collected pre-shift on the first day of study and post-shift on the third day of the study. RESULTS: The geometric mean exposure over the three work shifts were 0.02 ppm benzene, 0.05 ppm toluene, 0.03 ppm ethylbenzene, and 0.06 ppm xylene. Benzene in air was significantly correlated with unmetabolized benzene in blood (r = 0.69, p < 0.001) and urine (r = 0.64, p < 0.001), but not with urinary t,t-MA (r = 0.27, p = 0.20). Toluene in air was highly correlated with the internal dose of toluene in both blood (r = 0.70, p < 0.001) and urine (r = 0.73, p < 0.001). Co-exposures were present; however, an interaction of metabolism was not likely at these low benzene and toluene exposures. CONCLUSION: Urinary benzene, but not t,t-MA, was a reliable biomarker for benzene at low exposure levels. Urinary toluene was a useful biomarker for toluene exposure. Xylene and ethylbenzene air levels were low. Dermal exposure assessment needs to be performed in future studies among these workers.

Hopf NB; Kirkeleit J; Bråtveit M; Succop P; Talaska G; Moen BE

2012-04-01

14

PREFRACTIONATION OF HIGH BENZENE PRECURSORS’ FEED FOR HYBRID REFORMER UNIT  

Directory of Open Access Journals (Sweden)

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

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

2008-01-01

15

[Lesser validity of urinary benzene than S-phenylmercapturic acid for measuring occupational and environmental exposure to very low concentrations of benzene].  

UK PubMed Central (United Kingdom)

AIM: To study the validity of urinary benzene as a biomarker of low and very low exposure to this toxicant, as compared with t,t-muconic acid (t,t-MA) and S-phenylmercapturic acid (SPMA), also taking into account the influence of cigarette smoking and co-exposure to toluene on the urinary excretion of benzene. MATERIALS AND METHODS: The results obtained in two different studies were compared: in the first, workers occupationally exposed to low concentrations of benzene (18 fuel tanker drivers and 23 filling station attendants) were compared with 31 controls and in the second, workers exposed to very low concentrations of benzene (the same 23 filling station attendants) were compared with the 31 controls. Exposure to airborne benzene and toluene was monitored with passive personal samplers (Radiello). Then the urine collected at the end of the work shift was analyzed for t,t-MA, SPMA and urinary benzene. All participants also filled out a questionnaire about their lifestyle habits. RESULTS: There were no differences among the three groups in terms of age and smoking habit. Occupational exposure to benzene and toluene and the urinary concentrations of t,t-MA, SPMA and urinary benzene were higher in the fuel tanker drivers than the filling station attendants and higher in the latter than in the controls. Cigarette smoking was found to be associated with urinary excretion of t,t-MA, SPMA and urinary benzene at both low and very low exposure to benzene. The biomarkers t,t-MA, SPMA and urinary benzene were almost always correlated, for both low and very low exposure to benzene. Notably, for low exposure to benzene a dependency relation was found with the levels of t,t-MA, SPMA and urinary benzene on both cigarette smoking and airborne benzene, whereas for very low exposure to benzene there was a dependency relation of SPMA on cigarette smoking and airborne benzene, of urinary benzene only on cigarette smoking and of t,t-MA on none of the variables considered. CONCLUSIONS: For occupational exposure to low concentrations of benzene, urinary benzene and SPMA showed a comparable validity, while for exposure to very low concentrations of this toxicant the validity of SPMA was confirmed while urinary benzene was found to be less useful. Cigarette smoking was the main factor conditioning the excretion of all the biomarkers of benzene in conditions of both low and very low exposure to the toxicant, so for the analysis of occupational exposure to benzene it is best to recommend abstention from smoking at least in the hours immediately before urine collection.

Lovreglio P; Barbieri A; Carrieri M; Sabatini L; Fracasso ME; Doria D; Drago I; Basso A; D'Errico MN; Bartolucci GB; Violante FS; Soleo L

2011-04-01

16

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)

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.)

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

2004-12-15

17

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

Energy Technology Data Exchange (ETDEWEB)

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

CHOI, A

2006-03-20

18

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

Science.gov (United States)

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

Laowagul, Wanna; Yoshizumi, Kunio

19

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1999-09-01

20

Dissociation of benzene and methylene chloride based on enhanced dissociative electron attachment to highly excited molecules  

Science.gov (United States)

We present preliminary results on a low-pressure glow-discharge-based process for the destruction of dilute concentrations of volatile organic compounds. Methylene chloride and benzene were studied in dilute mixtures with Ar, Ne and He rare gases. The destruction efficiency was observed to increase with increasing pressure. This and other observations are compatible with molecular dissociation by dissociative electron attachment to high-lying Rydberg states of molecules produced via excitation transfer from the metastable states of the rare gases.

McCorkle, Dennis L.; Ding, Weixing; Ma, Cheng-Yu; Pinnaduwage, Lal A.

1999-01-01

 
 
 
 
21

Method for synthesis of high-octane rating gasoline components by combination of crude benzene and propylene  

UK PubMed Central (United Kingdom)

The present invention relates to method of alkylating crude benzene and propylene to synthesize high octane value gasoline. Under the action of catalyst, crude benzene and propylene are alkylated into high octane value and high arene gasoline component. Technologically, the present invention features that catalytically reformed oil fraction is rectified to obtain crude benzene, and the crude benzene and propylene are alkylated into isopropyl benzene. The present invention has the advantages of no limitation of the benzene content in reformed oil on its added amount to gasoline and the capacity of using distilled crude benzene in producing high octane value component via alkylation.

YAO YAPING; ZHOU QI; ZHAO LIZHI

22

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 ben(>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)

1998-01-01

23

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

UK PubMed Central (United Kingdom)

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

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

1996-01-01

24

Flat high concentration devices  

Energy Technology Data Exchange (ETDEWEB)

During the last five years new concentrators achieving the theoretical maximum acceptance-angle-concentration product have appeared. In addition, some of these concentrators are very compact (concentrator depth/aperture diameter smaller than 1/3). The feasibility of these concentrators for photovoltaic applications is studied. It is concluded that these concentrators may be useful for high concentration cells (irradiance for maximum efficiency greater than 800 suns) if these cells have a small size (diameter smaller than 5 mm). The concentrators may provide for this case an acceptance angle of {approx} {+-}2.7 degrees with concentration factor around 1,000x and a concentrator depth 10 times the cell diameter. Instantaneous direct insolation and ambient temperature measurements of Madrid and a thermal model of the heat sink is used to calculate the annual electric energy output with which different concentration factors are compared. Concentration of 1,000x is close to the one giving the maximum annual electrical output.

Minano, J.C.; Gonzalez, J.C.; Zanesco, I. [ETSI Telecomunicacion, Madrid (Spain). Inst. de Energia Solar

1994-12-31

25

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

UK PubMed Central (United Kingdom)

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

Olszowski T; K?os A

2013-09-01

26

Examinations about indoor air concentrations of benzene in dwellings near gasoline stations; Untersuchungen ueber Benzolkonzentrationen in der Innenraumluft von Wohnungen in Nachbarschaft von Tankstellen  

Energy Technology Data Exchange (ETDEWEB)

High concentrations of the human cancerogenic substance - benzene - are found in the gasoline station area because of the benzene content of gasoline. New investigations with total 171 dwellings of non-smokers in Berlin have resulted in that the indoor air concentrations of benzene in the dwellings immediately near the gasoline stations show at least two-fold as high as those in the dwellings far away from the gasoline stations. As the most important precautionary measures of health protection, reducing the benzene content of gasoline to a maximum of 1%, introducing the refueling vapour balance in all gasoline stations as early as possible and renunciation of new buildings with integrated gasoline stations should be required. (orig.) [Deutsch] Aufgrund des Benzolgehaltes von Benzin treten in Tankstellenbereichen hohe Konzentrationen des humankanzerogenen Stoffes in der Luft auf. Neue Untersuchungen in Berlin an insgesamt 171 Wohnraeumen von Nichtrauchern habe ergeben, dass Tankstellen direkt benachbarte Raeume eine mindestens zweimal so starke Benzolbelastung der Innenraumluft aufweisen wie Vergleichswohnungen. Als wichtigste Massnahme zum Gesundheitsschutz werden die Reduzierung des Benzolgehaltes im Benzin auf hoechstens 1 Vol.-%, die fruehestmoegliche Einfuehrung des Gasrueckfuehrverfahrens an allen Tankstellen und der Verzicht auf Hausneubauten mit eingebauten Tankstellen gefordert. (orig.)

Laue, W [Senatsverwaltung fuer Gesundheit, Abt. V - Umweltmedizin, Berlin (Germany); Piloty, M.; Li, D.; Marchl, D.

1994-09-01

27

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

Energy Technology Data Exchange (ETDEWEB)

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

Poirier, M.R.

2000-08-23

28

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

Directory of Open Access Journals (Sweden)

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

Abdulrahman Bahrami; Hosien Mahjub; Marzieh Sadeghian; Farideh Golbabaei

2011-01-01

29

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

UK PubMed Central (United Kingdom)

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

Thottempudi V; Forohor F; Parrish DA; Shreeve JM

2012-09-01

30

Collisional deactivation of highly vibrationally excited benzene pumped at 248 nm  

Energy Technology Data Exchange (ETDEWEB)

Highly vibrationally excited gas-phase benzene was prepared with a pulsed excimer laser operating at 248 nm, and the subsequent collisional deactivation was monitored with time-resolved infrared fluorescence (IRF) from the C-H stretch modes near 3,050 cm{sup {minus}1}. Very low pressure photolysis mass spectrometric experiments were carried out to determine whether reaction of the benzene occurs at this laser wavelength and can complicate the energy-transfer investigation. The quantum yield for benzene loss was determined to be 3 {plus minus} 1%, consistent with previous experiments (Nakashima, N.; Yoshihara, K. J. Chem. Phys. 1982, 77, 6040) that found photoproducts as the result of multiphoton excitation. The only detectable gas-phase product was H{sub 2}, which had a quantum yield of 0.8 {plus minus} 0.3%. Energy-transfer data were obtained for 19 collider gases, including unexcited benzene. The inversion technique for converting the observed IRF decay to <>, the bulk average energy, was examined in detail, and a careful propagation of errors analysis performed.

Yerram, M.L.; Brenner, J.D.; King, K.D.; Barker, J.R. (Univ. of Michigan, Ann Arbor (USA))

1990-08-09

31

Highly concentrating Fresnel lenses  

International Nuclear Information System (INIS)

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

1979-01-01

32

High Dispersion Barium Sulfate Nanoparticles Prepared with Dodecyl Benzene Sulfonic Acid  

Science.gov (United States)

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

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

2012-12-01

33

Reduction of benzene emission. Parking garages and road tunnels in residential areas; Beperking van benzeen-uitstoot. Parkeergarages en verkeerstunnels in woongebieden  

Energy Technology Data Exchange (ETDEWEB)

Benzene is carcinogenic. Therefore, in the Netherlands residents are protected against too high exposure of benzene concentrations by means of the `Air Quality Benzene Decree`. Parking garages and tunnels for traffic contribute considerably to the total concentration of benzene in the ambient atmosphere. It has been investigated how the annual average benzene concentration in the ventilated outlet air of tunnels and parking garages can be reduced to 1 {mu}g/m{sup 3} in an economically efficient way. 3 figs., 3 tabs.

Speulman, H. [Parking Systems Benelux, Capelle a/d IJssel (Netherlands)

1997-01-01

34

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

Energy Technology Data Exchange (ETDEWEB)

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.

Misra, V.; Pandey, S.D.; Viswanathan, P.N. (Industrial Toxicology Research Centre, Lucknow (India))

1991-10-01

35

Dinitroamino benzene derivatives: a class new potential high energy density compounds.  

UK PubMed Central (United Kingdom)

Dinitroamino benzene derivatives are designed and studied in detail with quantum chemistry method. The molecular theory density, heats of formation, bond dissociation energies, impact sensitive and detonation performance are investigated at DFT-B3LYP/6-311G** level. The results of detonation performance indicated most of the compounds have better detonation velocity and pressure than RDX and HMX. The N-N bond can be regard as the trigger bond in explosive reaction, and the bond dissociation energies of trigger bond are almost not affected by the position and number of substituent group. The impact sensitive are calculated by two different theory methods. It is found that the compounds, which can become candidates of high energy materials, have smaller H50 values than RDX and HMX. It is hoped that this work can provide some basis information for further theory and experiment studies of benzene derivatives.

Cao Q

2013-06-01

36

Identification of the source of benzene concentrations at Texas City during SHARP using an adjoint neighborhood-scale transport model and a receptor model  

Science.gov (United States)

Aerodyne Research Inc. mobile laboratory performed real-time in-situ measurements of volatile organic compounds, nitrogen oxides, and formaldehyde in Texas City, Texas on 7 May 2009 during the Formaldehyde and olefins from Large Industrial Releases experiment of the 2009 Study of Houston Atmospheric Radical Precursors (SHARP) campaign. Our goal was to identify and quantify emission sources within the largest industrial facility in Texas City most likely responsible for measured concentrations of benzene, an important VOC and hazardous air pollutant. The Houston Advanced Research Center inverse air quality model has been used to infer benzene emission rates from all potential source locations that could account for the benzene concentrations measured by the mobile lab in the vicinity of the facility. A Positive Matrix Factorization receptor model was also applied to the concentrations measured by the mobile lab, the results of which strongly supported the source attribution specified by the inverse model. The two independent source apportionment techniques both implicated flare, storage tank, and ultraformer units in the facility as significant contributors to emission plumes of elevated benzene concentrations observed by the mobile lab. The emissions of some of the flare and tank units were found to be greater than reported in emission inventories by about an order of magnitude.

Buzcu-Guven, Birnur; Olaguer, Eduardo P.; Herndon, Scott C.; Kolb, Charles E.; Knighton, W. Berk; Cuclis, Alex E.

2013-07-01

37

Biofiltration control of VOC emissions: Butane and benzene  

Energy Technology Data Exchange (ETDEWEB)

Laboratory studies were conducted on the biological elimination of n-butane and benzene from air streams using activated sludge-treated compost biofilters. Four types of experimental biofilter systems were developed: a bench scale packed tower system used primarily for kinetic studies; a small scale column system used to study the effects of different filter media on n-butane removal; a three stage system used to study benzene elimination; and a static batch biofilter system used to study the effects of temperature, compost water content, compost pH, and initial benzene concentrations on benzene elimination. Removal efficiencies greater than 90% were obtained for n-butane. Removal followed first order kinetics at inlet concentrations less than 25 ppM n-butane and zero order kinetics above 100 ppM n-butane. Removal of benzene followed fractional order kinetics for inlet concentrations from 15 to 200 ppM benzene. Thus, the removal of benzene is both mass transfer and bioreaction limited for the concentration range studied. The removal efficiency of benzene was found to be highly dependent on compost water content, compost pH, and temperature. Compost showed a low capacity for benzene removal, which suggested that degradation of these hydrocarbons required different species of microorganisms.

Allen, E.R. [Univ. of Florida, Gainesville, FL (United States)

1995-12-31

38

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

Energy Technology Data Exchange (ETDEWEB)

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

Gonzalez Vanderhaghen, D.E

1998-12-31

39

ITP Filtrate Benzene Removal Alternatives  

Energy Technology Data Exchange (ETDEWEB)

Existing ITP filtrate hold tanks may provide sufficient capacity and residence time to strip dissolved benzene from the incoming filtrate using nitrogen sparging in the bottom of the old tanks. This is based on equilibrium supported by late Wash test data using aged washed slurry. Theoretical considerations indicate that benzene stripping will be more difficult from the ITP unwashed high salt filtrates due to reduced mass transfer. Therefore experimental sparging data is needed to quantify the theoretical effects.Foaming limits which dictate allowable sparging rate will also have to be established. Sparging in the hold tanks will require installation of sintered metal spargers, and possibly stirrers and foam monitoring/disengagement equipment. The most critical sparging needs are at the start of the precipitation/concentration cycle, when the filtrate flux rate is the highest,and at the end of wash cycle where Henry`s equilibrium constant falls off,requiring more gas to sparge the dissolved benzene. With adequate recycle (for proper distribution) or sparging in the old tanks, the 30 inch column could be used for the complete ITP process. A courser packing would reduce back pressure while enabling benzene stripping. The Late Wash Tests indicate adequate benzene stripping even at reduced gas flow. This will require experimental verification under ITP conditions. Using the 30 in. column vs 18 in. during the wash cycle will enhance stripping without need for additional sparging provided the minimum flow requirements are met.

Dworjanyn, L.O. [Westinghouse Savannah River Company, Aiken, SC (United States)

1993-05-21

40

A method for isolating high temperature organic heat carriers from the bottoms of benzene pyrolysis  

Energy Technology Data Exchange (ETDEWEB)

A method is proposed for isolating high temperature organic heat carriers (VT) from the bottoms from benzene pyrolysis with the use of multistaged rectification, which includes first stage isolation of a distillate of a fraction which contains diphenyl, o-terphenyl, m-terphenyl and p-terphenyl, with subsequent isolation from it of the terphenyl mixtures and industrial terphenyls. In order to simplify the technology of the process and to fully use the bottoms of benzene pyrolysis, the latter is subjected to three stage vacuum rectification with removal of the first stage at a temperature of 290 to 300 degrees and a vacuum of 100 to 105 millimeters as the bottom product of the fraction, which contains m-terphenyl, p-terphenyl and higher polyphenyls, from which, through distillation at a temperature of 380 to 400 degrees and atmospheric pressure, industrial p-terphenyl is isolated, along with higher polyphenyls, and the distillate from the first stage, which is rectified with bleed off as a distillate of the second stage of the terphenyl mixture.

Chechetkin, A.V.; Kaplan, Ye.P.; Kharaz, D.I.; Nikishin, G.I.

1982-01-01

 
 
 
 
41

Epithermal electron capture cross-section of benzene in ethanol  

Energy Technology Data Exchange (ETDEWEB)

A reduction in the biphenyl anion yield in pulse-irradiated ethanol has been observed in the presence of high (0,5-4,0m) benzene concentrations. Using these data a value for the epithermal electron capture cross-section of benzene has been calculated as omicron = 6(+-3) x 10(sup-17) cmS.

Salter, L.F.

1985-09-01

42

High-electron-density C6H6 units: stable ten-pi-electron benzene complexes.  

UK PubMed Central (United Kingdom)

The first stable benzene molecule with ten pi electrons is predicted. Stability is achieved through barium atoms acting as an electron-donating "matrix" to C6H6 in the inverted sandwich complex [Ba2(C6H6)]. The bis(barium)benzene complex has been computed at the density functional level of theory by using the hybrid functional mPW1PW91. Ab initio calculations were performed by using the coupled-cluster expansion, CCSD(T). Nucleus independent chemical shift (NICS) indices imply distinct aromatic character in the benzene ring of bis(barium)benzene. The D6h-symmetric structure with a 1A(1g) electronic ground state represents a thermochemically stable, aromatic benzene molecule with four excess pi electrons, stabilised by two barium ions. A possible molecular wire, built up from Ba end-capped thorium-benzene "sandwiches", is discussed.

Diefenbach M; Schwarz H

2005-05-01

43

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

Energy Technology Data Exchange (ETDEWEB)

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.

JAHN, STEVEN

2005-04-20

44

Reducing benzene  

Energy Technology Data Exchange (ETDEWEB)

This article discusses the forms of benzene in desalter effluent brine and use of chemical treatments for benzene control in wastewaters from US refineries. The regulation of benzene emissions by the US Environmental Protection Agency (EPA), the imposition of total annual benzene (TAB) limits, and the use of source reduction as an alternative to remediation are considered along with the large contribution of desalting operations to the TAB for a refinery. The ability to chemically treat benzene in desalter effluent brine as an economic alternative to remediation is explored. The impact of obverse (water-in-oil) emulsions, reverse (oil in water) emulsions, colloidal solutions, and molecular solutions on the benzene in desalter brine is considered along with their chemical treatments. Two case studies of the reduction of benzene in effluent brine are presented with the dosages of chemicals used provided.

Moffitt, M.; Dion, M.; Hart, P. [BetzDearborn Inc. (United States)

2001-11-01

45

Benzene oxidation coupled to sulfate reduction  

Science.gov (United States)

Highly reduced sediments from San Diego Bay, Calif., that were incubated under strictly anaerobic conditions metabolized benzene within 55 days when they were exposed initially to I ??M benzene. The rate of benzene metabolism increased as benzene was added back to the benzene-adapted sediments. When a [14C]benzene tracer was included with the benzene added to benzene-adapted sediments, 92% of the added radioactivity was recovered as 14CO2. Molybdate, an inhibitor of sulfate reduction, inhibited benzene uptake and production of 14CO2 from [14C]benzene. Benzene metabolism stopped when the sediments became sulfate depleted, and benzene uptake resumed when sulfate was added again. The stoichiometry of benzene uptake and sulfate reduction was consistent with the hypothesis that sulfate was the principal electron acceptor for benzene oxidation. Isotope trapping experiments performed with [14C]benzene revealed that there was no production of such potential extracellular intermediates of benzene oxidation as phenol, benzoate, p-hydroxybenzoate, cyclohexane, catechol, and acetate. The results demonstrate that benzene can be oxidized in the absence of O2, with sulfate serving as the electron acceptor, and suggest that some sulfate reducers are capable of completely oxidizing benzene to carbon dioxide without the production of extracellular intermediates. Although anaerobic benzene oxidation coupled to chelated Fe(III) has been documented previously, the study reported here provides the first example of a natural sediment compound that can serve as an electron acceptor for anaerobic benzene oxidation.

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

1995-01-01

46

Discovery of highly potent triazole antifungal derivatives by heterocycle-benzene bioisosteric replacement.  

Science.gov (United States)

On the basis of our previously discovered triazole antifungal lead compounds, heterocycle-benzene bioisosteric replacement was used to improve their pharmacokinetic profile. The designed new triazole derivatives have good antifungal activity toward a wide range of pathogenic fungi. Their binding mode with the target enzyme was clarified by molecular docking. The MIC value of the highly potent compound 8f against Candida albicans, Candida tropicalis, and Cryptococcus neoformans is 0.016 ?g/mL, 0.004 ?g/mL, and 0.016 ?g/mL, respectively. Moreover, preliminary pharmacokinetic studies revealed that it showed improved oral absorption as compared to the lead compound iodiconazole and deserved for further evaluations. PMID:23643831

Jiang, Zhigan; Wang, Yan; Wang, Wenya; Wang, Shengzheng; Xu, Bo; Fan, Guorong; Dong, Guoqiang; Liu, Yang; Yao, Jianzhong; Miao, Zhenyuan; Zhang, Wannian; Sheng, Chunquan

2013-04-17

47

Discovery of highly potent triazole antifungal derivatives by heterocycle-benzene bioisosteric replacement.  

UK PubMed Central (United Kingdom)

On the basis of our previously discovered triazole antifungal lead compounds, heterocycle-benzene bioisosteric replacement was used to improve their pharmacokinetic profile. The designed new triazole derivatives have good antifungal activity toward a wide range of pathogenic fungi. Their binding mode with the target enzyme was clarified by molecular docking. The MIC value of the highly potent compound 8f against Candida albicans, Candida tropicalis, and Cryptococcus neoformans is 0.016 ?g/mL, 0.004 ?g/mL, and 0.016 ?g/mL, respectively. Moreover, preliminary pharmacokinetic studies revealed that it showed improved oral absorption as compared to the lead compound iodiconazole and deserved for further evaluations.

Jiang Z; Wang Y; Wang W; Wang S; Xu B; Fan G; Dong G; Liu Y; Yao J; Miao Z; Zhang W; Sheng C

2013-06-01

48

Method for producing benzene arenes from coarse benzene  

UK PubMed Central (United Kingdom)

A process for preparing benzene-series arylhydrocarbon from crude benzene includes such steps as proportionally adding common triplet oil, hydrorefining, fractionating, extracting in solvent, distilling and rectifying to obtain high-purity (more than 99.9%) benzene, toluene and xylene.

SHE XICHUN ZHU

49

[Benzene in soft drinks: a study in Florence (Italy)].  

Science.gov (United States)

The aim of this study was to determine the amount of benzene present in soft drinks sold in Florence (Italy). We analyzed 28 different types of soft drinks, by measuring concentrations of benzoic acid, sorbic acid, ascorbic acid (using high performance liquid chromatography with UV detection) and benzene (using gas chromatography and mass spectrometry). Data was analysed by using SPSS 18.0.Traces of benzene were detected in all analyzed beverages, with a mean concentration of 0.45 µg/L (range: 0.15-2.36 µg/L). Statistically significant differences in mean benzene concentrations were found between beverages according to the type of additive indicated on the drink label, with higher concentrations found in beverages containing both ascorbic acid and sodium benzoate. Two citrus fruit-based drinks were found to have benzene levels above the European limit for benzene in drinking water of 1 µg /L. Sodium benzoate and ascorbic acid were also detected in the two drinks.In conclusion, not all soft drink producers have taken steps to eliminate benzoic acid from their soft drinks and thereby reduce the risk of formation of benzene, as recommended by the European Commission. Furthermore, the presence of benzene in trace amounts in all beverages suggests that migration of constituents of plastic packaging materials or air-borne contamination may be occurring. PMID:23073373

Bonaccorsi, Guglielmo; Perico, Andrea; Colzi, Alessio; Bavazzano, Paolo; Di Giusto, Maurizio; Lamberti, Ilaria; Martino, Gianrocco; Puggelli, Francesco; Lorini, Chiara

50

[Benzene in soft drinks: a study in Florence (Italy)].  

UK PubMed Central (United Kingdom)

The aim of this study was to determine the amount of benzene present in soft drinks sold in Florence (Italy). We analyzed 28 different types of soft drinks, by measuring concentrations of benzoic acid, sorbic acid, ascorbic acid (using high performance liquid chromatography with UV detection) and benzene (using gas chromatography and mass spectrometry). Data was analysed by using SPSS 18.0.Traces of benzene were detected in all analyzed beverages, with a mean concentration of 0.45 µg/L (range: 0.15-2.36 µg/L). Statistically significant differences in mean benzene concentrations were found between beverages according to the type of additive indicated on the drink label, with higher concentrations found in beverages containing both ascorbic acid and sodium benzoate. Two citrus fruit-based drinks were found to have benzene levels above the European limit for benzene in drinking water of 1 µg /L. Sodium benzoate and ascorbic acid were also detected in the two drinks.In conclusion, not all soft drink producers have taken steps to eliminate benzoic acid from their soft drinks and thereby reduce the risk of formation of benzene, as recommended by the European Commission. Furthermore, the presence of benzene in trace amounts in all beverages suggests that migration of constituents of plastic packaging materials or air-borne contamination may be occurring.

Bonaccorsi G; Perico A; Colzi A; Bavazzano P; Di Giusto M; Lamberti I; Martino G; Puggelli F; Lorini C

2012-07-01

51

Purifying a fraction of coke chemical benzene, toluene and xylene using concentrated sulfuric acid with an additive of alpha methylstyrol fraction  

Energy Technology Data Exchange (ETDEWEB)

C6H6 with a thiophene content of 0.05 to 0.08 percent is produced with purification of a benzene, toluene and xylene fraction by a known method using concentrated H2SO4. The purification of a benzene, toluene and xylene (BTK) fraction with a thiophene content of 0.55 percent at 20 to 80 degrees using 2 to 8 percent concentrated H2SO4 with an additive of 0.5 to 4 percent alpha methylstyrol fraction (MSF), produced as a by product in synthesis of phenol by a coumol method is studied in laboratory conditions. It is established that in order to produce C6H6 with a thiophene content of less than 0.01 percent from a benzene, toluene and xylene fraction by means of S2SO4 with an additive of 2.5 percent alpha methylstyrol fraction, greater than or equal to 5 percent H2SO4 is required. With the same volume of H2SO4, a 6 percent additive of 0.5 to 4 percent alpha methylstryol fraction reduces the content of the thiophene in the C6H6 to 0.0120 to 0.0010 percent. The most effective purification is at 40 degrees, a 5 percent concentration of H2SO4 and an additive of 2 to 2.5 percent alpha methylsytrol fraction. The results of laboratory tests are confirmed in commercial tests.

Tecza, W.; Lisicki, Z.

1984-01-01

52

Temporal variability of benzene concentration in the ambient air of Delhi: a comparative assessment of pre- and post-CNG periods.  

UK PubMed Central (United Kingdom)

CNG (compressed natural gas) was fully implemented in public transport system in Delhi in December 2002. The study assesses the benzene concentration trends at two busy traffic intersections and a background site in Delhi, India. Monitoring was done for two different time periods viz; in the year 2001-2002 (pre-CNG) and two winter months (January and February) of the year 2007 (post-CNG) to assess the impact of various policy measures adopted by the government of Delhi to improve the air quality in the city. Annual average benzene concentration for the pre-CNG period was found to be 86.47+/-53.24 microg m(-3). Average benzene concentrations for the winter months (January-February) of pre- and post-CNG periods were 116.32+/-51.65 microg m(-3) and 187.49+/-22.50 microg m(-3), respectively. Enhanced values could be solely attributed to the increase in the vehicular population from 3.5 million in the year 2001-2002 to approximately 5.1 millions in the year 2007.

Khillare PS; Hoque RR; Shridhar V; Agarwal T; Balachandran S

2008-06-01

53

Temporal variability of benzene concentration in the ambient air of Delhi: a comparative assessment of pre- and post-CNG periods.  

Science.gov (United States)

CNG (compressed natural gas) was fully implemented in public transport system in Delhi in December 2002. The study assesses the benzene concentration trends at two busy traffic intersections and a background site in Delhi, India. Monitoring was done for two different time periods viz; in the year 2001-2002 (pre-CNG) and two winter months (January and February) of the year 2007 (post-CNG) to assess the impact of various policy measures adopted by the government of Delhi to improve the air quality in the city. Annual average benzene concentration for the pre-CNG period was found to be 86.47+/-53.24 microg m(-3). Average benzene concentrations for the winter months (January-February) of pre- and post-CNG periods were 116.32+/-51.65 microg m(-3) and 187.49+/-22.50 microg m(-3), respectively. Enhanced values could be solely attributed to the increase in the vehicular population from 3.5 million in the year 2001-2002 to approximately 5.1 millions in the year 2007. PMID:18082950

Khillare, P S; Hoque, Raza Rafiqul; Shridhar, Vijay; Agarwal, Tripti; Balachandran, S

2007-11-09

54

Biological monitoring of benzene exposure during maintenance work in crude oil cargo tanks.  

Science.gov (United States)

We investigated the association between the individual concentrations of benzene in the breathing zone and the concentrations of benzene in the blood and urine among workers maintaining crude oil cargo tanks. Benzene exposure was measured during three consecutive 12h work days among 13 tank workers and 9 unexposed referents (catering section). Blood and urine samples were collected pre-shift on the first day, post-shift on the third day, and pre-next shift on the following morning. The workers used half-mask air-purifying respirators, but not all workers used these systematically. The individual geometric mean benzene exposure in the breathing zone of tank workers over 3 days was 0.15 ppm (range 0.01-0.62 ppm). The tank workers' post-shift geometric mean benzene concentrations were 12.3 nmol/l in blood and 27.0 nmol/l in urine versus 0.7 nmol/l for both blood and urine among the referents. Benzene in the work atmosphere was highly correlated with the internal concentration of benzene both in post-shift blood (r=0.87, P<0.001) and post-shift urine (r=0.90, P<0.001), indicating that the varying use of respirators did not explain much of the variability in absorbed benzene. The results showed that, despite low benzene exposure in this work atmosphere and the use of personal protective equipment to a varying degree, the tank workers had a significant uptake of benzene that correlated highly with benzene exposure. The internal concentration of benzene was higher than expected considering the measured individual benzene exposure, probably due to an extended work schedule of 12h and physical strain during tank work. Control measures should be improved for processes, which impose a potential for increased absorption of benzene upon the workers. PMID:17049507

Kirkeleit, Jorunn; Riise, Trond; Bråtveit, Magne; Pekari, Kaija; Mikkola, Jouni; Moen, Bente E

2006-08-30

55

Biological monitoring of benzene exposure during maintenance work in crude oil cargo tanks.  

UK PubMed Central (United Kingdom)

We investigated the association between the individual concentrations of benzene in the breathing zone and the concentrations of benzene in the blood and urine among workers maintaining crude oil cargo tanks. Benzene exposure was measured during three consecutive 12h work days among 13 tank workers and 9 unexposed referents (catering section). Blood and urine samples were collected pre-shift on the first day, post-shift on the third day, and pre-next shift on the following morning. The workers used half-mask air-purifying respirators, but not all workers used these systematically. The individual geometric mean benzene exposure in the breathing zone of tank workers over 3 days was 0.15 ppm (range 0.01-0.62 ppm). The tank workers' post-shift geometric mean benzene concentrations were 12.3 nmol/l in blood and 27.0 nmol/l in urine versus 0.7 nmol/l for both blood and urine among the referents. Benzene in the work atmosphere was highly correlated with the internal concentration of benzene both in post-shift blood (r=0.87, P<0.001) and post-shift urine (r=0.90, P<0.001), indicating that the varying use of respirators did not explain much of the variability in absorbed benzene. The results showed that, despite low benzene exposure in this work atmosphere and the use of personal protective equipment to a varying degree, the tank workers had a significant uptake of benzene that correlated highly with benzene exposure. The internal concentration of benzene was higher than expected considering the measured individual benzene exposure, probably due to an extended work schedule of 12h and physical strain during tank work. Control measures should be improved for processes, which impose a potential for increased absorption of benzene upon the workers.

Kirkeleit J; Riise T; Bråtveit M; Pekari K; Mikkola J; Moen BE

2006-12-01

56

High-concentration tritium sensor  

Energy Technology Data Exchange (ETDEWEB)

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

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

2004-01-01

57

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

International Nuclear Information System (INIS)

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

2012-04-04

58

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

Science.gov (United States)

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

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

2013-03-19

59

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

UK PubMed Central (United Kingdom)

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

Wu HY; Shieh FK; Kao HM; Chen YW; Deka JR; Liao SH; Wu KC

2013-05-01

60

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

Energy Technology Data Exchange (ETDEWEB)

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

Dworjanyn, L.O.

1997-11-14

 
 
 
 
61

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

International Nuclear Information System (INIS)

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

1997-01-01

62

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-07-01

63

Benzene in the workplace  

Energy Technology Data Exchange (ETDEWEB)

It has long been recognized that overexposure to benzene could result in damage to the blood-forming organs of the body. More recently, it has become apparent that chronic high levels of exposure are associated with the development of leukemia. Animal experiments have also suggested that overexposure to benzene may result in certain reproductive risks. Toxicological and epidemiological evidence indicate that benzene is capable of causing serious blood effects at high levels. While the effects observed in animals are very weak, more research is underway to define the limits of exposure believed to be safe with respect to reproductive effects in workers of either sex. Levels of benzene in air at 10 ppM or less can be determined with sufficient accuracy to evaluate the integrated or peak exposures of workers during their working hours. Where exposure in excess of accepted levels occurs, substitution with other less toxic materials, coupled with adequate controls and strict work practices for handling benzene or benzene-containing compounds, are capable of minimizing or eliminating health hazards associated with this extremely important and useful chemical.

Brief, R.S.; Lynch, J.; Bernath, T.; Scala, R.A.

1980-09-01

64

Shock tube investigation of major pathways in the high-temperature pyrolysis of benzene  

Energy Technology Data Exchange (ETDEWEB)

The high-temperature pyrolysis of benzene, 1 and 2 mol % in krypton, has been studied in the shock tube with the laser-schlieren technique over 1900-2400 K and 0.2-1.0 atm. A completely successful modeling of the density gradient profiles and some time-of-flight mass spectra is achieved with a simple radical chain mechanism consisting of essentially just four reactions. The dissociation is solely CH bond scission (M) + C/sub 6/H/sub 6/ ..-->.. C/sub 6/H/sub 5/ + H + (M) whose rates are strongly dependent on both temperature and pressure in this range; this reaction is near second order for T > 2300 K. An RRKM fit to these data suggests a barrier of 112 +/- 2 kcal/mol, which corresponds to ..delta..H/sub f//sup 0//sub 298/ = 80 +/- 2 kcal/mol for the phenyl radical heat of formation, and an average collisional energy transfer of (-..delta..E)/sub all/ = 70 cm/sup -1/. The extrapolated K/sub infinity/ for this reaction is 2 x 10/sup 17/ exp(-118000 (cal)/RT) s/sup -1/ (1900-2400 K). The model also indicates a rate constant of 2.5 x 10/sup 14/ exp(-16000 (cal)/RT cm/sup 3//(mol s) (1900-2200 K) for the abstraction H + C/sub 6/H/sub 6/ ..-->.. C/sub 6/H/sub 5/ + H/sub 2/. 31 references, 9 figures, 3 tables.

Kiefer, J.H.; Mizerka, L.J.; Patel, M.R.; Wei, H.C.

1985-05-09

65

Bioaugmented remediation of high concentration BTEX-contaminated groundwater by permeable reactive barrier with immobilized bead.  

Science.gov (United States)

Ineffective biostimulation requires immediate development of new technologies for remediation of high concentration BTEX-contaminated (benzene, toluene, ethylbenzene and xylene) groundwater. In this study, bioaugmentation with Mycobacterium sp. CHXY119 and Pseudomonas sp. YATO411 immobilized bead was used to remediate BTEX-contaminated groundwater with about 100 mg l(-1) in total concentration. The batch test results showed that the CHXY119 and YATO411 immobilized bead completely biodegraded each BTEX compound, and the maximum biodegradation rates were 0.790 mg l(-1) h(-1) for benzene, 1.113 mg l(-1) h(-1) for toluene, 0.992 mg l(-1) h(-1) for ethylbenzene and 0.231 mg l(-1) h(-1) for p-xylene. The actual mineralization rates were 10.8% for benzene, 10.5% for toluene, 5.8% for ethylbenzene and 11.4% for p-xylene, which indicated that the bioremediation of BTEX by the immobilized bead requires a rather small oxygen supply. Degradation rates achieved by the bioaugmented permeable reactive barrier (Bio-PRB) system of the immobilized bead were 97.8% for benzene, 94.2% for toluene, 84.7% for ethylbenzene and 87.4% for p-xylene; and the toxicity of the groundwater fell by 91.2% after bioremediation by the bioaugmented PRB, which confirmed its great potential for remediating groundwater with high concentrations of contaminants. PMID:23200621

Xin, Bao-Ping; Wu, Chih-Hung; Wu, Cheng-Han; Lin, Chi-Wen

2012-11-12

66

Bioaugmented remediation of high concentration BTEX-contaminated groundwater by permeable reactive barrier with immobilized bead.  

UK PubMed Central (United Kingdom)

Ineffective biostimulation requires immediate development of new technologies for remediation of high concentration BTEX-contaminated (benzene, toluene, ethylbenzene and xylene) groundwater. In this study, bioaugmentation with Mycobacterium sp. CHXY119 and Pseudomonas sp. YATO411 immobilized bead was used to remediate BTEX-contaminated groundwater with about 100 mg l(-1) in total concentration. The batch test results showed that the CHXY119 and YATO411 immobilized bead completely biodegraded each BTEX compound, and the maximum biodegradation rates were 0.790 mg l(-1) h(-1) for benzene, 1.113 mg l(-1) h(-1) for toluene, 0.992 mg l(-1) h(-1) for ethylbenzene and 0.231 mg l(-1) h(-1) for p-xylene. The actual mineralization rates were 10.8% for benzene, 10.5% for toluene, 5.8% for ethylbenzene and 11.4% for p-xylene, which indicated that the bioremediation of BTEX by the immobilized bead requires a rather small oxygen supply. Degradation rates achieved by the bioaugmented permeable reactive barrier (Bio-PRB) system of the immobilized bead were 97.8% for benzene, 94.2% for toluene, 84.7% for ethylbenzene and 87.4% for p-xylene; and the toxicity of the groundwater fell by 91.2% after bioremediation by the bioaugmented PRB, which confirmed its great potential for remediating groundwater with high concentrations of contaminants.

Xin BP; Wu CH; Wu CH; Lin CW

2013-01-01

67

Occupational exposure to benzene in China.  

UK PubMed Central (United Kingdom)

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 benzene poisoning and the concentration in shoemaking factories. The prevalence of benzene induced aplastic anaemia in shoemakers was about 5.8 times that occurring in the general population. The results of this investigation show the need for a practicable hygiene standard to prevent benzene poisoning.

Yin SN; Li Q; Liu Y; Tian F; Du C; Jin C

1987-03-01

68

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

Energy Technology Data Exchange (ETDEWEB)

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

Yoshida, Ken; Uosaki, Yasuhiro [Department of Chemical Science and Technology, Faculty of Engineering, University of Tokushima, 2-1 Minamijosanjima-cho, Tokushima 770-8506 (Japan); Matubayasi, Nobuyuki; Nakahara, Masaru, E-mail: yoshida@chem.tokushima-u.ac.j [Institute for Chemical Research, Kyoto University, Uji, Kyoto, 611-0011 (Japan)

2010-03-01

69

High performance Fresnel-based photovoltaic concentrator.  

UK PubMed Central (United Kingdom)

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

Benítez P; Miñano JC; Zamora P; Mohedano R; Cvetkovic A; Buljan M; Chaves J; Hernández M

2010-04-01

70

ALUMINUM SILICATE-FREE, HIGHLY CONCENTRATED SUSPENSION CONCENTRATES OF METRIBUZIN  

UK PubMed Central (United Kingdom)

The invention relates to aqueous, aluminum silicate-free, highly concentrated suspension concentrates, containing the active substance metribuzin, one or more surfactants based on nonionic polymers from the 'acrylic grafted polymers' group, one or more thickeners based on anionic heteropolysaccharides from the xanthan gum group, one or more wetting agents and optionally other components such as antifoaming agents, antifreeze agents and preservatives and other surfactants differing from the aforesaid components.

SIXL FRANK; BICKERS UDO; KOPPERT HARRY; HOPERT JUERGEN

71

ALUMINIUM SILICATE-FREE, HIGHLY CONCENTRATED SUSPENSION CONCENTRATES OF METRIBUZIN  

UK PubMed Central (United Kingdom)

The invention relates to aqueous, aluminium silicate-free, highly concentrated suspension concentrates, containing the active substance metribuzin, one or more surfactants on the basis of non-ionic polymers from the group of acrylic grafted polymers, one or more thickeners on the basis of anionic heteropolysaccharides from the group xanthan gum, one or more wetting agents and optionally further constituents, such as defoamers, anti-freeze agents and preservatives as well as further surfactants other than the aforementioned constituents.

SIXL FRANK; BICKERS UDO; KOPPERT HARRY; HOPERT JUERGEN

72

Aluminium silicate-free, highly concentrated suspension concentrates of metribuzin  

UK PubMed Central (United Kingdom)

The invention relates to aqueous, aluminium silicate-free, highly concentrated suspension concentrates, containing the active substance metribuzin, one or more surfactants on the basis of non-ionic polymers from the group of acrylic grafted polymers, one or more thickeners on the basis of anionic heteropolysaccharides from the group xanthan gum, one or more wetting agents and optionally further constituents, such as defoamers, anti-freeze agents and preservatives as well as further surfactants other than the aforementioned constituents.

SIXL FRANK; BICKERS UDO; KOPPERT HARRY; HOPERT JURGEN

73

Development of a Biphasic Electroreactor with a Wet Scrubbing System for the Removal of Gaseous Benzene.  

UK PubMed Central (United Kingdom)

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

Govindan M; Chung SJ; Moon HH; Jang JW; Moon IS

2013-07-01

74

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

Science.gov (United States)

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

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

2011-06-15

75

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

UK PubMed Central (United Kingdom)

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

Aluri GS; Motayed A; Davydov AV; Oleshko VP; Bertness KA; Sanford NA; Rao MV

2011-07-01

76

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.

1992-01-01

77

Proposal of structures possessing high exciton concentration  

International Nuclear Information System (INIS)

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

2008-01-01

78

Ethyl benzene from ethane and benzene  

Energy Technology Data Exchange (ETDEWEB)

A new process to produce ethyl benzene for styrene production by employing a new zeolite catalyst starting with ethane and benzene. The demand for styrene is projected to growth due to new polymer technology under development.

Pogue, R. [Dow Chemical Co., Freeport, TX (United States)

1996-10-01

79

Critical micelle concentration in the AOT-water-benzene system as determined by small-angle neutron scattering  

Energy Technology Data Exchange (ETDEWEB)

We describe an approach to the experimental determination of the critical micelle concentration (CMC) in solutions of uncharged micelles by the analysis of small-angle neutron scattering data. It is shown that, in dilute solutions, the dependence of the product of forward scattering intensity and apparent squared radius of gyration is a linear function of the total surfactant concentration. The ratio of the two parameters of this function gives the concentration of surfactant in a monomeric state, which can be used as a reliable estimate of CMC. In the case under investigation (AOT + X.H{sub 2}O+C{sub 6}D{sub 6}) at X = 0 we found CMC = 0.80 {+-} 0.04 mM, which is in reasonable agreement with the values reported by the other authors. Our first experiments at X = 4.3 and X = 8.6 show CMC = 2.2 {+-} 1.0 mM and 1.5 {+-} 0.6 mM, respectively. It seems plausible that the addition of water does not cause any serious diminution of the CMC in this system. (orig.).

Gorski, N.; Ostanevich, Yu.M. (Joint Inst. for Nuclear Research, Dubna (USSR). Lab. of Neutron Physics)

1991-08-01

80

Benzene hematotoxicity and leukemogenesis  

Energy Technology Data Exchange (ETDEWEB)

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

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

1985-01-01

 
 
 
 
81

The use of acetylene and 1,3-butadiene as tracers for vehicular combustion in urban air and the estimation of the contributions of vehicular emissions to benzene, and alkane concentrations in the Edmonton industrial area  

Energy Technology Data Exchange (ETDEWEB)

Acetylene, propylene and 1,3-butadiene concentrations at two downtown urban sites in Alberta, Canada were used to characterize an area dominated by vehicular emissions. The relationship of acetylene with 1,3-butadiene at the Edmonton industrial site was similar to that observed for the two downtown sites. This suggesting that these volatile organic compounds, VOCs, can be used as tracers for vehicular emissions for the Edmonton industrial area. The tracer VOCs were found to correlate with benzene, n-butane, iso-butane, n-pentane, iso-pentane, n-heptane and n-octane concentrations for the two Alberta downtown sites. The best fit lines from the downtown sites were used to predict daily concentrations of benzene and alkanes at the Edmonton industrial site. During the winter, when benzene levels are predicted to reach a maximum of 4.5 to 6.5 m g/m{sup 3}, it is estimated that industrial sources contribute < 1 m g/m{sup 3} to ambient levels at the Edmonton industrial site. During the summer, when predicted benzene levels are at a minimum of 1 to 2 m g/m{sup 3}, industrial area sources dominate the ambient benzene levels at the Edmonton industrial site, and can contribute up to 6 m g/m{sup 3}. For alkanes, such as butane and pentane, industrial area sources or evaporative storage tank emissions dominate throughout the year. This dominance of industrial sources is also observed for n-heptane and n-octane during summer months. During the winter when predicted n-heptane and n-octane concentrations reach a maximum, 11 to 100% of ambient daily levels can be attributed to vehicular emissions.

Bailey, R. [Environment Canada, Edmonton, Alberta (Canada). Prairie and Northern Region; Wong, R. [Alberta Environmental Protection, Edmonton, Alberta (Canada); Dann, T.; Wang, D. [Environment Canada, Gloucester, Ontario (Canada). Environmental Protection Service

1998-12-31

82

Perinatal immunotoxicity of benzene toward mouse B cell development  

Energy Technology Data Exchange (ETDEWEB)

Benzene is widely used by chemical industries and exposure to benzene has been shown experimentally to be immunotoxic in adult animals. The present study addressed whether exposure of fetuses in utero to benzene compromises the development of fetal B lymphopoiesis and whether B-lymphocyte development recovers postnatally. Pregnant BALB/C dams were given intraperitoneal injections of benzene (100 mg/kg, twice daily) from day 12.5 of gestation through day 19.5 of gestation. Phenotypic analysis revealed that fetal liver cell suspensions from embryos exposed in utero contained fewer pre-B cells and B cells than corresponding controls. Fetal liver cell cultures established from these embryos also produced fewer B cells. In contrast, pre-B cells were elevated in the livers of 8-day-old neonates that had been exposed to benzene in utero. Moreover, responsiveness to the B-cell mitogen, LPS, was significantly decreased in spleen cell cultures derived from these neonates. The results indicate that in utero exposure to high concentrations of benzene alters fetal B lymphopoiesis and may compromise immune responsiveness postnatally.

Wierda, D.; King, A.; Luebke, R.; Reasor, M.; Smialowicz, R.J.

1989-01-01

83

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

Directory of Open Access Journals (Sweden)

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

?.?. ???????; ?.?. ???????; ?.?. ????????

2005-01-01

84

Highly concentrated foam formulation for blast mitigation  

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-12-14

85

A semiconductor gas sensor system for high throughput screening of heterogeneous catalysts for the production of benzene derivatives  

Science.gov (United States)

We used a semiconductor gas sensor system developed for odour discrimination for a rapid quantification of benzene derivatives which can be formed as the product of a catalytic reaction. Phenol can be obtained by the selective oxidation of benzene. The sensor system shows higher sensitivity to phenol than benzene. In particular, a SnO2 sensor sensitized with ZrO2 responds selectively to phenol. Aniline is provided as a reaction product between ammonia and benzene. The output signal of the gas sensor system increases when it is exposed to air containing aniline at the ppm level; on the other hand, the sensor output resulting from 1% ammonia in air does not increase so much. Cumene formation can be observed by the reaction of propane and benzene. The sensitivity of a SnO2 sensor sensitized with 12%SiO2-Al2O3 to cumene was about ten times higher than that to benzene. These results indicate that the semiconductor gas sensor system is useful for rapid screening of the catalyst for benzene functionalization.

Yamada, Yusuke; Ueda, Atsushi; Shioyama, Hiroshi; Maekawa, Toru; Kanda, Keisen; Suzuki, Kengo; Kobayashi, Tetsuhiko

2005-01-01

86

Electrochemistry of high concentration copper chloride complexes.  

UK PubMed Central (United Kingdom)

High concentrations of copper chloride solutions (in the molar range) are used in several industrial applications. In this work, we investigated the species distribution of copper chloride complexes and how to measure the copper concentration precisely at high concentrations using electrochemical methods, by including migrational effects. The latter, in fact, can be useful in determining the nature of the species in solution undergoing electron transfer at the electrode. The study indicates that the main species of Cu(II) complexes in high chloride concentration is CuCl4(2-) and the main species of Cu(I) complexes are CuCl2(-) and CuCl3(2-). However insoluble CuCl is an intermediate in the process and can deactivate the electrode surface. This can be ameliorated by increasing the temperature or Cl(-) concentration. Under these conditions, voltammetry with an ultramicroelectrode (UME) can measure copper concentration with good precision even at 1 M Cu(II) concentrations in a few molar chloride. The main charge of the species can be determined by fitting to a migration model.

Zhao H; Chang J; Boika A; Bard AJ

2013-08-01

87

Electrochemistry of high concentration copper chloride complexes.  

Science.gov (United States)

High concentrations of copper chloride solutions (in the molar range) are used in several industrial applications. In this work, we investigated the species distribution of copper chloride complexes and how to measure the copper concentration precisely at high concentrations using electrochemical methods, by including migrational effects. The latter, in fact, can be useful in determining the nature of the species in solution undergoing electron transfer at the electrode. The study indicates that the main species of Cu(II) complexes in high chloride concentration is CuCl4(2-) and the main species of Cu(I) complexes are CuCl2(-) and CuCl3(2-). However insoluble CuCl is an intermediate in the process and can deactivate the electrode surface. This can be ameliorated by increasing the temperature or Cl(-) concentration. Under these conditions, voltammetry with an ultramicroelectrode (UME) can measure copper concentration with good precision even at 1 M Cu(II) concentrations in a few molar chloride. The main charge of the species can be determined by fitting to a migration model. PMID:23848061

Zhao, Hong; Chang, Jinho; Boika, Aliaksei; Bard, Allen J

2013-07-30

88

Oxidative renaturation of lysozyme at high concentrations.  

UK PubMed Central (United Kingdom)

Newly synthesized cloned gene proteins expressed in bacteria frequently accumulate in insoluble aggregates or inclusion bodies. Active protein can be recovered by solubilization of inclusion bodies followed by renaturation of the solubilized (unfolded) protein. The recovery of active protein is highly dependent on the renaturation conditions chosen. The renaturation process is generally conducted at low protein concentrations (0.01-0.2 mg/mL) to avoid aggregation. We have investigated the potential of successfully refolding reduced and denatured hen egg white lysozyme at high concentrations (1 and 5 mg/mL). By varying the composition of the renaturation media, optimum conditions which kinetically favor proper folding over inactivation were found. Solubilizing agents such as guanidinium chloride (GdmCl) and folding aids such as L-arginine present in low concentrations during refolding effectively enhanced renaturation yields by suppressing aggregation resulting in reactivation yields as high as 95%. Quantitatively the kinetic competition between lysozyme folding and aggregation can be described using first-order kinetics for the renaturation reaction and third-order kinetics for the overall aggregation pathway. The rate constants for both reactions have been found to be strongly dependent on denaturant and thiol concentration. This strategy supercedes the necessity to reactivate proteins at low concentrations using large renaturation volumes. The marked increase in volumetric productivity makes this a viable option for recovering biologically active protein efficiently and in high yield in vitro from proteins produced as inclusion bodies within microbial cells.

Hevehan DL; De Bernardez Clark E

1997-05-01

89

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

UK PubMed Central (United Kingdom)

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.

Rahul; Mathur AK; Bala S; Majumder C

2012-12-01

90

[Setaria viridis tolerance of high zinc concentrations  

UK PubMed Central (United Kingdom)

The effect of high zinc concentrations on the growth and photosynthetic apparatus of Setaria viridis (L.) Beauv. was investigated under laboratory conditions and a vegetation experiment. The experiments showed that zinc concentrations of 10(-6) to 10(-3) M did not influence seed germination. Moreover, zinc in concentrations of 40 and 80 mg kg(-1) substrate had no significant effect on most of the plant growth parameters. However, higher metal concentrations (160 and 320 mg kg(-1) substrate) inhibited shoot biomass, leaf area, inflorescence length, and biomass. At the same time, parameters such as the content of chlorophyll (a + b), F0, F(v), and the F(v)/F(m) rate were not reduced even in the presence of zinc in the highest concentrations (320 mg kg(-1) substrate). S. viridis tolerance of high zinc concentrations, as well as its capacity to accumulate zinc in roots and shoots, suggests the plant can be used for phytoremediation of zinc polluted soils.

Kaznina NM; Titov AF; La?dinen GF; Talanov AV

2009-11-01

91

Biological monitoring of benzene exposure for process operators during ordinary activity in the upstream petroleum industry.  

UK PubMed Central (United Kingdom)

This study characterized the exposure of crude oil process operators to benzene and related aromatics during ordinary activity and investigated whether the operators take up benzene at this level of exposure. We performed the study on a fixed, integrated oil and gas production facility on Norway's continental shelf. The study population included 12 operators and 9 referents. We measured personal exposure to benzene, toluene, ethylbenzene and xylene during three consecutive 12-h work shifts using organic vapour passive dosimeter badges. We sampled blood and urine before departure to the production facility (pre-shift), immediately after the work shift on Day 13 of the work period (post-shift) and immediately before the following work shift (pre-next shift). We also measured the exposure to hydrocarbons during short-term tasks by active sampling using Tenax tubes. The arithmetic mean exposure over the 3 days was 0.042 ppm for benzene (range <0.001-0.69 ppm), 0.05 ppm for toluene, 0.02 ppm for ethylbenzene and 0.03 ppm for xylene. Full-shift personal exposure was significantly higher when the process operators performed flotation work during the shift versus other tasks. Work in the flotation area was associated with short-term (6-15 min) arithmetic mean exposure to benzene of 1.06 ppm (range 0.09-2.33 ppm). The concentrations of benzene in blood and urine did not differ between operators and referents at any time point. When we adjusted for current smoking in regression analysis, benzene exposure was significantly associated with the post-shift concentration of benzene in blood (P = 0.01) and urine (P = 0.03), respectively. Although these operators perform tasks with relatively high short-term exposure to benzene, the full-shift mean exposure is low during ordinary activity. Some evidence indicates benzene uptake within this range of exposure.

Bråtveit M; Kirkeleit J; Hollund BE; Moen BE

2007-07-01

92

Biological monitoring of benzene exposure for process operators during ordinary activity in the upstream petroleum industry.  

Science.gov (United States)

This study characterized the exposure of crude oil process operators to benzene and related aromatics during ordinary activity and investigated whether the operators take up benzene at this level of exposure. We performed the study on a fixed, integrated oil and gas production facility on Norway's continental shelf. The study population included 12 operators and 9 referents. We measured personal exposure to benzene, toluene, ethylbenzene and xylene during three consecutive 12-h work shifts using organic vapour passive dosimeter badges. We sampled blood and urine before departure to the production facility (pre-shift), immediately after the work shift on Day 13 of the work period (post-shift) and immediately before the following work shift (pre-next shift). We also measured the exposure to hydrocarbons during short-term tasks by active sampling using Tenax tubes. The arithmetic mean exposure over the 3 days was 0.042 ppm for benzene (range <0.001-0.69 ppm), 0.05 ppm for toluene, 0.02 ppm for ethylbenzene and 0.03 ppm for xylene. Full-shift personal exposure was significantly higher when the process operators performed flotation work during the shift versus other tasks. Work in the flotation area was associated with short-term (6-15 min) arithmetic mean exposure to benzene of 1.06 ppm (range 0.09-2.33 ppm). The concentrations of benzene in blood and urine did not differ between operators and referents at any time point. When we adjusted for current smoking in regression analysis, benzene exposure was significantly associated with the post-shift concentration of benzene in blood (P = 0.01) and urine (P = 0.03), respectively. Although these operators perform tasks with relatively high short-term exposure to benzene, the full-shift mean exposure is low during ordinary activity. Some evidence indicates benzene uptake within this range of exposure. PMID:17607018

Bråtveit, Magne; Kirkeleit, Jorunn; Hollund, Bjørg Eli; Moen, Bente E

2007-07-02

93

?-galactosidase stability at high substrate concentrations.  

UK PubMed Central (United Kingdom)

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

Warmerdam A; Boom RM; Janssen AE

2013-01-01

94

High level waste concentrate storage at WAK  

International Nuclear Information System (INIS)

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

1987-01-01

95

Longwall equipment sets with high production concentration  

Energy Technology Data Exchange (ETDEWEB)

Reviews coal production concentration in European countries in 1990. Trends in production and its cost over 1965-1990 are shown in graphs for France, Belgium, Poland, Czechoslovakia, Australia, the UK, FRG, USSR and USA. High capacity longwall equipment sets for thin (0.9-1.9 m) and medium-thick (2.5-4.0 m) coal seams are presented. The longwall equipment sets described feature high production concentration at a working face. The KSE-344 shearer of 300 kW is the first Polish shearer loader of the new generation equipped with automatic feed and operation diagnostics of the main assemblies. The KSM-780 longwall equipment set of 780 kW is equipped with an electric feed drive, operation diagnostics and automatic control.

Jarno, L.; Pretor, W.; Mazurkiewicz, T. (Centrum Mechanizacji Gornictwa KOMAG, Gliwice (Poland))

1992-03-01

96

DOE High Performance Concentrator PV Project  

Energy Technology Data Exchange (ETDEWEB)

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

McConnell, R.; Symko-Davies, M.

2005-08-01

97

Electronic noses for monitoring benzene occupational exposure in biological samples of Egyptian workers.  

UK PubMed Central (United Kingdom)

OBJECTIVES: Benzene is commonly emitted in several industries, leading to widespread environmental and occupational exposure hazards. While less toxic solvents have been substituted for benzene, it is still a component of petroleum products and is a trace impurity in industrial products resulting in continued higher occupational exposures in industrial settings in developing countries. MATERIALS AND METHODS: We investigated the potential use of an electronic nose (e-nose) to monitor the headspace volatiles in biological samples from benzene-exposed Egyptian workers and non-exposed controls. The study population comprised 150 non-smoking male workers exposed to benzene and an equal number of matching non-exposed controls. We determined biomarkers of benzene used to estimate exposure and risk including: benzene in exhaled air and blood; and its urinary metabolites such as phenol and muconic acid using gas chromatography technique and a portable e-nose. RESULTS: The average benzene concentration measured in the ambient air of the workplace of all studied industrial settings in Alexandria, Egypt; was 97.56 ± 88.12 ?g/m(3) (range: 4.69-260.86 ?g/m(3)). Levels of phenol and muconic acid were significantly (p < 0.001) higher in both blood and urine of benzene-exposed workers as compared to non-exposed controls. CONCLUSIONS: The e-nose technology has successfully classified and distinguished benzene-exposed workers from non-exposed controls for all measured samples of blood, urine and the exhaled air with a very high degree of precision. Thus, it will be a very useful tool for the low-cost mass screening and early detection of health hazards associated with the exposure to benzene in the industry.

Mohamed EI; Khalil GI; Abdel-Mageed SM; Bayoumi AM; Ramadan HS; Kotb MA

2013-03-01

98

Carburetor fuel with a maximum benzene concentration of 5% by weight of light coal oil. Vergaserkraftstoff mit einem Benzolgehalt von hoechstens 5 Gew. % aus Kohleleichtoel  

Energy Technology Data Exchange (ETDEWEB)

This invention concerns a carburetor fuel with a benzene content of not more than 5% by weight in which a purified or refined light carbon oil with a boiling range of about 60 to 185/sup 0/C is subjected to catalytic reforming. The reformer feedstock flow is divided by distillation into a fraction boiling above 85/sup 0/C which is subsequently catalytically reformed, and a fraction boiling below 85/sup 0/C which is combined with the obtained reformate.

Jankowski, A.; Fehrer, A.; Doehler, W.

1987-05-07

99

High-efficiency silicon concentrator cell commercialization  

Energy Technology Data Exchange (ETDEWEB)

This report summarizes the first phase of a forty-one month program to develop a commercial, high-efficiency concentrator solar cell and facility for manufacturing it. The period covered is November 1, 1990 to December 31, 1991. This is a joint program between the Electric Power Research Institute (EPRI) and Sandia National Laboratories. (This report is also published by EPRI as EPRI report number TR-102035.) During the first year of the program, SunPower accomplished the following major objectives: (1) a new solar cell fabrication facility, which is called the Cell Pilot Line (CPL), (2) a baseline concentrator cell process has been developed, and (3) a cell testing facility has been completed. Initial cell efficiencies are about 23% for the baseline process. The long-range goal is to improve this efficiency to 27%.

Sinton, R.A.; Swanson, R.M. [SunPower Corp., Sunnyvale, CA (US)

1993-05-01

100

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

Directory of Open Access Journals (Sweden)

Full Text Available Background: For its toxicity, benzene exposure is one of the main health concerns for high risk occupations like gasoline station workers. However, there is little knowledge about the effect of benzene metabolites on hematological parameters.Objective: To evaluate the correlation between the urinary level of trans, trans-muconic acid (t, t-MA), a benzene metabolite, and some hematological parameters in gasoline workers.Methods: We studied 102 gasoline station workers from 11 gasoline stations in Pathumwan district, central area of Bangkok, Thailand. Their blood and urine samples were analyzed for some hematological parameters and urinary t, t-MA analysis by high performance liquid chromatography (HPLC).Results: We found an inverse correlation between urinary t, t-MA concentration and hemoglobin level (r = 0.281, pConclusion: Exposure to benzene would cause bone marrow depression presenting as drop in hemoglobin, hematocrit and eosinophil counts.

T Tunsaringkarn; S Soogarun; A Palasuwan

2013-01-01

 
 
 
 
101

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.

1996-01-01

102

Determination of the unburnt benzene in the autovehicular emission  

Energy Technology Data Exchange (ETDEWEB)

The exahaust 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 tailpipe 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 apporach 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.

Latella, A.; Buttini, P. [Eniricerche SpA, Monterotondo (Italy); Corno, C. [Eniricerche SpA, Milan (Italy); Marchesi, G. F. [Euron, San Donato Milanese, Milan (Italy)

1996-06-01

103

Multispecies hydrodynamic dispersion under high concentration gradients.  

UK PubMed Central (United Kingdom)

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

Sarioglu MS; Kucuker MA; Copty NK

2013-01-01

104

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

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese Em condições críticas, a água pode solvatar moléculas hidrofóbicas, tornando-se um solvente poderoso para agentes apolares. Para discutir o efeito da pressão em agregados de benzeno em água, foram executadas seis simulações consecutivas de 5000 ps (picossegundos) por modelagem e dinâmica molecular de 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 (more) 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 boxes at different pressure conditions, ranging from 1 bar to 5 kbar. Radius of gyration, diffusion coefficient, radial atomic pair distribution functions, number of hydrogen bo (more) nds 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.

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

2009-01-01

105

BEVERAGE OF CONCENTRATED VINEGAR CONTAINING HIGH CONCENTRATION COLLAGEN  

UK PubMed Central (United Kingdom)

A method of manufacturing of a concentrated vinegar beverage is provided to promote collagen composition and moisturizing effect maintenance of the skin by adding a brewing vinegar, sour taste agent, saccharides, sweetener, sugar alcohols, fruit juice, purified water, and protease into a collagen peptide. A mixed solution of a purified water, fruit juice, brewed vinegar is adjusted to weak acid nature of PH 5.0 is mixed at low speed. The collagen peptide powder of 5~30% is injected into the mixed solution, and the temperature of the mixed solution is maintained with 35~40 C and the enzyme reaction is made. A reactant is filtered and an acidulant, the saccharides, and artificial sweetener are mixed into it, and then it is refrigerated..

LEE JONG NAM

106

Diverse microbial species survive high ammonia concentrations  

Science.gov (United States)

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

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

2012-04-01

107

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.

1990-01-01

108

Enhanced ?-frustration in carbo-benzenic chromophores.  

UK PubMed Central (United Kingdom)

The synthesis, structure, and absorption spectra of highly ?-frustrated carbo-benzenes with indolic enamine substituents more or less directly conjugated to the C18 macro-aromatic core are described, and their peculiar reactivity is analyzed.

Baglai I; Maraval V; Bijani C; Saffon-Merceron N; Voitenko Z; Volovenko YM; Chauvin R

2013-08-01

109

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

UK PubMed Central (United Kingdom)

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

Gupta A; Sarkar J; Kumar A

2013-02-01

110

An analysis of historical exposures of pressmen to airborne benzene (1938-2006).  

UK PubMed Central (United Kingdom)

Benzene is an aromatic hydrocarbon that, with sufficient cumulative lifetime doses, can cause acute myelogenous leukemia. Because of its volatility and solvent properties, it was used in the printing industry in inks, ink solvents, and cleaning agents from the 1930s to the 1970s. This analysis represents the first known attempt to gather and synthesize the available data on historical airborne benzene concentrations in printing facilities and exposures to pressmen. The sources of fugitive benzene vapors from printing operations have been identified as evaporation from ink fountains, exposed sections of the printing cylinder, the paper web, the paper post exit, and spilled ink. In addition, specific activities that could lead to benzene exposure, such as filling the fountains, using solvents to clean the press, and using solvents as personal cleaning agents, potentially occurred multiple times per work period. Eighteen studies were identified that reported workplace airborne concentrations in printing facilities between 1938 and 2006. Typical benzene air concentrations, considering both personal and area samples of various durations, were as high as 200 p.p.m. in the 1930s through the 1950s, 3-35 p.p.m. in the 1960s, 1.3-16 p.p.m. in the 1970s, 0.013-1 in the 1980s, and far less than 1 p.p.m. in the 1990s and 2000s. The decrease in benzene air concentrations by the late 1970s was likely to be linked to the decreased benzene content of printing materials, increased engineering controls, and to more stringent occupational exposure limits.

Novick RM; Keenan JJ; Gross SA; Paustenbach DJ

2013-07-01

111

Production of high concentrations of yeast  

Energy Technology Data Exchange (ETDEWEB)

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

1981-11-10

112

Benzene and lymphohematopoietic malignancies in humans.  

UK PubMed Central (United Kingdom)

BACKGROUND: Quantitative evaluations of benzene-associated risk for cancer have relied primarily on findings from a cohort study of highly exposed U.S. rubber workers. An epidemiologic investigation in China (NCI/CAPM study) extended quantitative evaluations of cancer risk to a broader range of benzene exposures, particularly at lower levels. METHODS: We review the evidence implicating benzene in the etiology of hematopoietic disorders, clarify methodologic aspects of the NCI/CAPM study, and examine the study in the context of the broader literature on health effects associated with occupational benzene exposure. RESULTS: Quantitative relationships for cancer risk from China and the U.S. show a relatively smooth increase in risk for acute myeloid leukemia and related conditions over a broad dose range of benzene exposure (below 200 ppm-years mostly from the China study and above 200 ppm-years mostly from the U.S. study). CONCLUSIONS: Risks of acute myeloid leukemia and other malignant and nonmalignant hematopoietic disorders associated with benzene exposure in China are consistent with other information about benzene exposure, hematotoxicity, and cancer risk, extending evidence for hematopoietic cancer risks to levels substantially lower than had previously been established. Published 2001 Wiley-Liss, Inc.

Hayes RB; Songnian Y; Dosemeci M; Linet M

2001-08-01

113

Bioremediation of chlorinated benzene compounds  

Energy Technology Data Exchange (ETDEWEB)

In early 1994, investigations at a pharmaceutical manufacturing site revealed extensive areas of soil contaminated with chlorinated benzenes. The soil was a heavy clay and contained chlorobenzene (CB), 1,2-dichlorobenzene (referred to in this paper as DCB), and small amounts of 1,3- and 1,4-dichlorobenzene and other solvents. The soil was bioremediated in a pilot-scale treatment using an ex situ process with various inorganic and organic amendments. Approximately 90% of the DCB mass present in the soil was removed over a period of 2 to 3 weeks. Up to 100-fold increases in both total heterotrophs and specific degraders were observed. Residual concentrations of chlorinated benzenes were generally below detection limits. Adding organic matter did not appear to significantly enhance the treatment efficiency. Mass balance calculations applied to the treatment indicated that less than 5% of the chlorinated benzenes were removed by volatilization. Evidence was obtained that approximately 90% of the DCB was removed by biodegradation in these pilot-scale trials. Laboratory shake flask trials were conducted which confirmed that the soils in the pilot-scale treatment contained microorganisms capable of mineralizing CB and DCB.

Peck, P.C.; Rhodes, S.H. [Minenco Bioremediation Services, N. Sydney, New South Wales (Australia); Guerin, T.F. [Minenco Bioremediation Services, Bundoora, Victoria (Australia)

1995-12-31

114

Benzene Monitor System report  

International Nuclear Information System (INIS)

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

1992-01-01

115

Benzene Monitor System report  

Energy Technology Data Exchange (ETDEWEB)

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

Livingston, R.R.

1992-10-12

116

Human risk assessment of benzene after a gasoline station fuel leak.  

UK PubMed Central (United Kingdom)

OBJECTIVE: To assess the health risk of exposure to benzene for a community affected by a fuel leak. METHODS: Data regarding the fuel leak accident with, which occurred in the Brasilia, Federal District, were obtained from the Fuel Distributor reports provided to the environmental authority. Information about the affected population (22 individuals) was obtained from focal groups of eight individuals. Length of exposure and water benzene concentration were estimated through a groundwater flow model associated with a benzene propagation model. The risk assessment was conducted according to the Agency for Toxic Substances and Disease Registry methodology. RESULTS: A high risk perception related to the health consequences of the accident was evident in the affected community (22 individuals), probably due to the lack of assistance and a poor risk communication from government authorities and the polluting agent. The community had been exposed to unsafe levels of benzene (> 5 µg/L) since December 2001, five months before they reported the leak. The mean benzene level in drinking water (72.2 µg/L) was higher than that obtained by the Fuel Distributer using the Risk Based Corrective Action methodology (17.2 µg/L).The estimated benzene intake from the consumption of water and food reached a maximum of 0.0091 µg/kg bw/day (5 x 10-7 cancer risk per 106 individuals). The level of benzene in water vapor while showering reached 7.5 µg/m3 for children (1 per 104 cancer risk). Total cancer risk ranged from 110 to 200 per 106 individuals. CONCLUSIONS: The population affected by the fuel leak was exposed to benzene levels that might have represented a health risk. Local government authorities need to develop better strategies to respond rapidly to these types of accidents to protect the health of the affected population and the environment.

Santos Mdos A; Távora BE; Koide S; Caldas ED

2013-06-01

117

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

International Nuclear Information System (INIS)

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

2007-01-01

118

High concentration herbicide suitable for oniongrass plants  

UK PubMed Central (United Kingdom)

The present invention relates to herbicide, and is especially herbicide for killing common rue herb. The herbicide for killing common rue herb consists of glyphosate 35-85 wt%, diclofop-methyl 10-15 wt% and engine oil 4-52 wt%. It has common rue herb killing rate as high as 92-97.5 % to raise grass producing capacity. It has the features of no need of water in use, low consumption, fast acting and high efficiency.

CHENGZHANG ZHAO; CUIQIN YIN; RUIJUN LONG; XIAOHONG WEI

119

Benzene-filled pore method: a method of measuring external surface areas applicable to zeolites with low-to-high Si-to-Al ratios  

Energy Technology Data Exchange (ETDEWEB)

This study is an investigation of various adsorbates (water, hexane, and benzene) applied to several kinds of zeolites (Y, mordenite, and ZSM-5). The adsorption of water, hexane, and benzene is evaluated as a method of measuring the eternal surface areas of zeolites.

Inomata, M.; Yamada, M.; Okada, S.; Niwa, M.; Murakami, Y.

1986-07-01

120

Air pollution monitoring in Como urban areas. Benzene  

International Nuclear Information System (INIS)

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

 
 
 
 
121

High concentration Mn ion implantation in Si  

Science.gov (United States)

Recent controversial reports of possible above room temperature ferromagnetism in high dose Mn implanted Si samples was the motivation for examining this interesting Mn-Si binary system. 50 keV Mn+ ions were implanted into n-type CZ (0 0 1) Si wafers up to 5 × 1016 ions/cm2 at room temperature, leading to the formation of disordered surface Mn/Si layers. The Mn implanted samples were subjected to further treatments by pulsed laser annealing in air. The distribution and evolution of the Mn dopant in the Si host upon thermal treatments is characterized by Rutherford backscattering, cross-sectional transmission electron microscopy and Raman scattering measurements.

Peng, Nianhua; Jeynes, Christopher; Bailey, Melanie J.; Adikaari, Damitha; Stolojan, Vlad; Webb, Roger P.

2009-05-01

122

High-contrast grating based planar light concentrators  

Science.gov (United States)

A new planar light concentrator design is proposed by using unique diffraction properties of high-contrast subwavelength gratings (HCGs). HCGs have the ability to diffract the incoming light at steep angles with very high efficiency. By integrating the HCGs on top of planar glass substrates, light can be guided in the glass leading to high concentration at the edges. Finite difference time domain simulation results show that concentration ratio close to 50 can be achieved by optimizing the grating parameters. These planar light concentrators find application in various areas including concentrated solar power, light pipes and spectrum splitters.

Pesala, Bala

2012-02-01

123

The structures of CO, NO and benzene on various transition metal surfaces: Overview of LEED (low-energy electron diffraction) and HREELS (high-resolution electron energy loss) results  

Energy Technology Data Exchange (ETDEWEB)

Recent results are summarized concerning the adsorption structures of carbon monoxide (CO) and nitric oxide (NO) chemisorbed on various transition metal surfaces, and of benzene (C6H6) on Pd, Rh and Pt(111). These results were for the most part obtained with intensity analysis of low-energy electron diffraction (LEED) and high-resolution electron energy loss spectroscopy (HREELS).

Ohtani, H.; Van Hove, M.A.; Somorjai, G.A.

1987-06-01

124

Benzene and superior counterpart; Benzene et homologues superieurs  

Energy Technology Data Exchange (ETDEWEB)

A century ago, the first case of purpura and acute anemia provoked by benzene was described. Afterwards, others important toxic effects in relation with the exposure to this solvent were known: medullar aplasia, acute leukemia,carcinogenesis. The chronic intoxication by benzene is called benzenism, the term of benzolism is devoted to the intoxication provoked by the mixture of benzene and superior counterparts: toluene, xylenes. (N.C.)

NONE

1998-07-01

125

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

UK PubMed Central (United Kingdom)

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

Kreider ML; Unice KM; Panko JM; Burns AM; Paustenbach DJ; Booher LE; Gelatt RH; Gaffney SH

2010-11-01

126

Isolation and characterization of benzene-tolerant Rhodococcus opacus strains.  

Science.gov (United States)

Twenty-two benzene-utilizing bacteria were isolated from soil samples. Among them, three isolates were highly tolerant to benzene. They grew on benzene when liquid benzene was added to the basal salt medium at 10--90% (v/v). Taxonomical analysis identified the benzene-tolerant isolates as Rhodococcus opacus. One of the benzene-tolerant isolates, designated B-4, could utilize many aromatic and aliphatic hydrocarbons including benzene, toluene, styrene, xylene, ethylbenzene, propylbenzene, n-octane and n-decane as sole sources of carbon and energy. Strain B-4 grew well in the presence of 10% (v/v) organic solvents that it was capable of using as growth substrates. Genetic analysis revealed the benzene dioxygenase pathway is involved in benzene catabolism in strain B-4. A deletion-insertion mutant defective in the benzene dioxygenase large and small subunits genes (bnz A 1 and bnz A 2) was as tolerant to organic solvents as the wild-type strain B-4, suggesting that utilization or degradation of organic solvents is not essential for the organic solvent tolerance of R. opacus B-4. PMID:16233805

Na, Kyung-Su; Kuroda, Akio; Takiguchi, Noboru; Ikeda, Tsukasa; Ohtake, Hisao; Kato, Junichi

2005-04-01

127

Isolation and characterization of benzene-tolerant Rhodococcus opacus strains.  

UK PubMed Central (United Kingdom)

Twenty-two benzene-utilizing bacteria were isolated from soil samples. Among them, three isolates were highly tolerant to benzene. They grew on benzene when liquid benzene was added to the basal salt medium at 10--90% (v/v). Taxonomical analysis identified the benzene-tolerant isolates as Rhodococcus opacus. One of the benzene-tolerant isolates, designated B-4, could utilize many aromatic and aliphatic hydrocarbons including benzene, toluene, styrene, xylene, ethylbenzene, propylbenzene, n-octane and n-decane as sole sources of carbon and energy. Strain B-4 grew well in the presence of 10% (v/v) organic solvents that it was capable of using as growth substrates. Genetic analysis revealed the benzene dioxygenase pathway is involved in benzene catabolism in strain B-4. A deletion-insertion mutant defective in the benzene dioxygenase large and small subunits genes (bnz A 1 and bnz A 2) was as tolerant to organic solvents as the wild-type strain B-4, suggesting that utilization or degradation of organic solvents is not essential for the organic solvent tolerance of R. opacus B-4.

Na KS; Kuroda A; Takiguchi N; Ikeda T; Ohtake H; Kato J

2005-04-01

128

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

UK PubMed Central (United Kingdom)

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

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

2012-11-01

129

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

Science.gov (United States)

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

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

2012-11-01

130

Anomalously high radon concentrations in a dwelling in Okinawa, Japan  

International Nuclear Information System (INIS)

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

2009-01-01

131

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Workers in the coke oven industry are potentially exposed to low concentrations of benzene. There is a need to establish a well validated biological monitoring procedure for low level benzene exposure. The use of breath and blood benzene and urinary phenol has been explored in conjunction with perso...

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

132

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

UK PubMed Central (United Kingdom)

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

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

2011-03-01

133

Kinetic study of saccharomyces strains: performance at high sugar concentrations  

Energy Technology Data Exchange (ETDEWEB)

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

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

1985-08-01

134

Leukemia risk associated with benzene exposure in the Pliofilm cohort  

Energy Technology Data Exchange (ETDEWEB)

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

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

1996-12-01

135

Decreased benzene evaporative emission from an oxygenated fuel  

Energy Technology Data Exchange (ETDEWEB)

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

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

1994-12-31

136

Characteristics of wet grinding of highly concentrated coal water slurry  

Energy Technology Data Exchange (ETDEWEB)

In an effort to provide basic data helpful for production of highly concentrated coal water slurry, the wet grinding characteristics of coal water mixtures (CWMs) at high concentrations are investigated by conducting batch preparation tests using a laboratory-scale ball mill. For the tests, 12 different coal samples are employed together with three anonic dispersing agents. measurements show that the use of a dispersion agent can greatly increase the wet grindability of highly concentrated CWMs. This is attributable to improved movements of the balls due to a decrease in the apparent viscosity at low shear rates. Different types of coal show widely different grindabilities, which is attributed to the differences in flocculation force of coal particles. As to the particle size distribution, high-concentration wet grinding is characterized by a larger content of fine particles compared to wet grinding or low-concentration wet grinding. (13 figs, 4 tabs, 3 refs)

Ito, Hayami; Tatsumi, Shuhei; Kajibata, Yoshihiro; Takao, Shoichi; Ozaki, Hironori; Katahata, Tadashi

1988-03-10

137

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

Science.gov (United States)

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

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

2010-01-01

138

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.  

UK PubMed Central (United Kingdom)

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

Mura MC; De Felice M; Morlino R; Fuselli S

2010-01-01

139

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

Directory of Open Access Journals (Sweden)

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

SB Mortazavi, A Sabzali, A Rezaee

2005-01-01

140

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

Energy Technology Data Exchange (ETDEWEB)

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.

Georgeton, G.K.; Gaughan, T.P.; Taylor, G.A.

1993-09-10

 
 
 
 
141

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-05-01

142

Multijunction Photovoltaic Technologies for High-Performance Concentrators: Preprint  

Energy Technology Data Exchange (ETDEWEB)

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

McConnell, R.; Symko-Davies, M.

2006-05-01

143

Multijunction Photovoltaic Technologies for High-Performance Concentrators  

Energy Technology Data Exchange (ETDEWEB)

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

McConnell, R.; Symko-Davies, M.

2006-01-01

144

Benzene gamma-radiolysis on MgO surfaces  

International Nuclear Information System (INIS)

Influence of MgO surface coverage with benzene on the mechanism of radiolysis has been investigated. Products of degradation of benzene are mainly produced for low surface coverage, whereas for high surface coverage - oligomeric and polymeric products, such as biphenyl (main product), o-terphenyl and products of their hydrogenation are obtained. (author) 14 refs.; 4 figs.

1991-01-01

145

Rheological properties of coal-water highly concentrated suspensions  

Energy Technology Data Exchange (ETDEWEB)

High solid concentrated suspensions are more and more used , like coal- water slurries . They are generally stabilized according to an electrostatic repulsion. The measurements of the zeta or electrokinetic potential constitute a means to gain an idea of the stability of such suspensions. Thus, a suspension is stable if the surface charge of the particles is high. In principle, the zeta potential must be higher in absolute value than 60 mV. With concentrated suspensions (50 % of solid), zeta potential can be determined using a mass transfer apparatus which eliminates sedimentation effects by continuous rotation of the measurement cell (30 cycles per minute) during the determination of electrophoretic mobility. But this technique also becomes inadequate if the solid concentration exceeds 60 %. Even sedimentation measurements (sediment height) lead to erroneous results. Indeed, the study of highly concentrated suspensions shows that the sedimentation speed becomes very much smaller than that of corresponding diluted suspensions (Stokes equation). In fact, stability measurements of concentrated suspensions do not exist. Some authors apply the drawing off technique which consists of introducing the concentrated suspension in a test-tube and drawing off a part of the suspension at two different levels after a given sedimentation time. The inconvenience of the technique is that it cannot be used with suspension concentrations exceeding 60%. We intend in this paper to apply penetrometry in order to obtain information both on the stability and the fluidity of highly concentrated coal in water slurries.

Hamieh, T.; Siffert, B. [Centre de Recherches sur la Physico-Chimie des Surfaces Solides, Mulhouse (France)

1993-12-31

146

High Stokes shift perylene dyes for luminescent solar concentrators.  

UK PubMed Central (United Kingdom)

Highly efficient plastic based single layer Luminescent Solar Concentrators (LSCs) require the design of luminophores having complete spectral separation between absorption and emission spectra (large Stokes shift). We describe the design, synthesis and characterization of a new perylene dye possessing Stokes shift as high as 300 meV, fluorescent quantum yield in the LSC slab of 70% and high chemical and photochemical stability.

Sanguineti A; Sassi M; Turrisi R; Ruffo R; Vaccaro G; Meinardi F; Beverina L

2013-02-01

147

LIQUID FERTILIZER INCORPORATING BIOSOLIDS AND HIGH CONCENTRATIONS OF AMMONIUM  

UK PubMed Central (United Kingdom)

This invention is directed to a method of manufacturing a liquid agricultura l fertilizer utilizing biosolids and high concentrations of nitrogen and other essential plant nutrients and the resulting products.

BURNHAM JEFFREY C; DAHMS GARY L

148

Process for producing a high concentration coal-water slurry  

Energy Technology Data Exchange (ETDEWEB)

A process is described for continuously and automatically producing a high concentration coal-water slurry. It includes a method of monitoring, evaluating and adjusting the process to provide a good quality product.

Shoji, K.; Ohtani, Y.; Kikkawa, H.; Terada, H.; Murata, M.; Meguri, N.

1990-05-15

149

Process for producing a high concentration coal-water slurry  

Energy Technology Data Exchange (ETDEWEB)

This invention relates to a coal-water slurry, and more particularly it relates to a process for producing a coal-water slurry having a good stability, a high coal concentration and a low viscosity with minimal settlings.

Kikkawa, H.

1989-01-11

150

Benzene generation from phenylborate decomposition in saltstone  

Energy Technology Data Exchange (ETDEWEB)

High Level Waste Engineering requested SRTC to determine the effect of tetraphenylborate (TPB), triphenylboron (3PB), diphenylborine acid (2PB), and phenylboronic acid (1PB) on the Saltstone process. A previous SRTC report documented benzene evolution from phenylborate decomposition over 91 days, 28 day toxic characteristic leaching procedure (TCLP) results and interactions between phenylborates and components in the saltstone dry chemicals. The ITP Flowsheet team asked SRTC to continue to measure benzene evolution from saltstone samples prepared with 3PB and 2PB. This report documents that work.

Poirier, M.R.

2000-04-19

151

Applications of nonimaging optics for very high solar concentrations  

Energy Technology Data Exchange (ETDEWEB)

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

O`Gallagher, J.; Winston, R.

1997-12-31

152

Case study of elevated layers of high sulfate concentration  

International Nuclear Information System (INIS)

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

1979-01-01

153

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2001-11-01

154

Microalgae Tolerance to High Concentrations of Carbon Dioxide: A Review  

Directory of Open Access Journals (Sweden)

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

Fadhil M. Salih

2011-01-01

155

Application of passive sampling on assessment of concentration distribution and health risk of volatile organic compounds at a high-tech science park.  

UK PubMed Central (United Kingdom)

The objectives of this study are to investigate the volatile organic compound (VOC) distribution using passive samplers and to assess the resulting health risks in a high-tech science industrial park. With the advantages of passive sampling techniques, long-term and wide-area samples are collected. The results show TVOC concentrations in summer, fall, winter, and spring are 7.14 ± 5.66 ppb, 18.17 ± 5.81 ppb, 10.30 ± 3.54 ppb, and 14.56 ± 4.53 ppb, respectively; those on weekdays and weekends are 14.36 ± 6.80 ppb and 9.87 ± 4.86 ppb, respectively; and those in industrial and residential zones are 12.97 ± 0.39 ppb and 11.13 ± 0.68 ppb, respectively. Based on concentration variations, and benzene, toluene, ethylbenzene, and xylene ratios, we can resolve the source origins. Health risks are assessed based on the resulting concentrations. In the case of non-cancer chronic effects, long-term exposure to these concentrations does not support there is a risk of adverse health effects. However, potential cancer risks of exposure to these concentrations may occur, especially to carbon tetrachloride and benzene. By applying this study's procedures, information on VOC concentration distribution, source identification, and health assessment can be obtained and they are applicable to similar studies.

Peng CY; Hsiao SL; Lan CH; Huang YL

2013-01-01

156

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

International Nuclear Information System (INIS)

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

1993-01-01

157

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1993-08-01

158

Disappearance of high temperature superconductivity induced by high carrier concentrations  

International Nuclear Information System (INIS)

It is shown that samples of La2 - xSrxCuO4 prepared under 100 bar oxygen pressure exhibit a metallic conductivity which increases as x increases up to x = 0.34. In spite of this behavior, superconductivity disappears with Tc decreasing from x = 0.15 to x = 0.25. This decrease in Tc is shown to be continuous (and not dominated by phase separation). Such decreases in Tc are shown to be common feature of high temperature superconductors, being observed in YBa2Cu3Oy like systems as well as in doped Bi 2212 and T1 1201 compounds.

1989-01-01

159

Benzene vapor recovery and processing  

International Nuclear Information System (INIS)

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

1991-01-01

160

Outdoor radon and traffic load levels as cumulative indicators of PM10 and benzene air pollution.  

Science.gov (United States)

A new simple cumulative index, named Critical Index (CI), linearly dependent on traffic load and outdoor 222Rn levels (as related to the air mixing condition) was introduced in order to determine the cumulative effect of traffic and atmospheric dilution on PM10 (particles with aerodynamic diameter < 10 microm) and Benzene concentrations in Milan (Italy) air in the years 2000 and 2001. Benzene, PM10 data were obtained from the public air quality monitoring stations. The traffic load was evaluated by the number of vehicles circulating in a street in the centre of Milan. Outdoor 222Rn measurements were carried out by the authors. Traffic data and mixing layer height (estimated through the outdoor 222Rn air activity) combined in a cumulative index, allowed to demonstrate the correlation of traffic load with high Benzene and PM10 pollution levels without exception. Implications: Through the introduction of a new simple cumulative index that is linearly dependent on traffic load and outdoor radon levels (as related to the air mixing condition), it was possible to ascertain the cumulative effect of traffic and atmospheric dilution on PM10 and benzene concentrations in Milan air in the years 2000 and 2001. The proposed methodology will be used to monitor the situation with data collected 10 yr later, in order to evaluate air quality improvement taking into account the influence of different meteorological conditions of the two periods compared. PMID:24010378

Somigliana, Anna; Lerda, Donata

2013-08-01

 
 
 
 
161

Outdoor radon and traffic load levels as cumulative indicators of PM10 and benzene air pollution.  

UK PubMed Central (United Kingdom)

A new simple cumulative index, named Critical Index (CI), linearly dependent on traffic load and outdoor 222Rn levels (as related to the air mixing condition) was introduced in order to determine the cumulative effect of traffic and atmospheric dilution on PM10 (particles with aerodynamic diameter < 10 microm) and Benzene concentrations in Milan (Italy) air in the years 2000 and 2001. Benzene, PM10 data were obtained from the public air quality monitoring stations. The traffic load was evaluated by the number of vehicles circulating in a street in the centre of Milan. Outdoor 222Rn measurements were carried out by the authors. Traffic data and mixing layer height (estimated through the outdoor 222Rn air activity) combined in a cumulative index, allowed to demonstrate the correlation of traffic load with high Benzene and PM10 pollution levels without exception. Implications: Through the introduction of a new simple cumulative index that is linearly dependent on traffic load and outdoor radon levels (as related to the air mixing condition), it was possible to ascertain the cumulative effect of traffic and atmospheric dilution on PM10 and benzene concentrations in Milan air in the years 2000 and 2001. The proposed methodology will be used to monitor the situation with data collected 10 yr later, in order to evaluate air quality improvement taking into account the influence of different meteorological conditions of the two periods compared.

Somigliana A; Lerda D

2013-08-01

162

Characteristics of Occupational Exposure to Benzene during Turnaround in the Petrochemical Industries.  

UK PubMed Central (United Kingdom)

OBJECTIVES: The level of benzene exposure in the petrochemical industry during regular operation has been well established, but not in turnaround (TA), where high exposure may occur. In this study, the characteristics of occupational exposure to benzene during TA in the petrochemical companies were investigated in order to determine the best management strategies and improve the working environment. This was accomplished by evaluating the exposure level for the workers working in environments where benzene was being produced or used as an ingredient during the unit process. METHODS: From 2003 to 2008, a total of 705 workers in three petrochemical companies in Korea were studied. Long- and short-term (< 1 hr) samples were taken during TAs. TA was classified into three stages: shut-down, maintenance and start-up. All works were classified into 12 occupation categories. RESULTS: The long-term geometric mean (GM) benzene exposure level was 0.025 (5.82) ppm (0.005-42.120 ppm) and the short-term exposure concentration during TA was 0.020 (17.42) ppm (0.005-61.855 ppm). The proportions of TA samples exceeding the time-weighted average, occupational exposure level (TWA-OEL in Korea, 1 ppm) and the short-term exposure limit (STEL-OEL, 5 ppm) were 4.1% (20 samples of 488) and 6.0% (13 samples of 217), respectively. The results for the benzene exposure levels and the rates of exceeding the OEL were both statistically significant (p < 0.05). Among the 12 job categories of petrochemical workers, mechanical engineers, plumbers, welders, fieldman and scaffolding workers exhibited long-term samples that exceeded the OEL of benzene, and the rate of exceeding the OEL was statistically significant for the first two occupations (p < 0.05). CONCLUSION: These findings suggest that the periodic work environment must be assessed during non-routine works such as TA.

Chung EK; Shin JA; Lee BK; Kwon J; Lee N; Chung KJ; Lee JH; Lee IS; Kang SK; Jang JK

2010-09-01

163

Morphological responses to high sugar concentrations differ from adaptation to high salt concentrations in the xerophilic fungi Wallemia spp.  

UK PubMed Central (United Kingdom)

Fungi from the food-borne basidiomycetous genus Wallemia, which comprises Wallemia ichthyophaga, Wallemia muriae and Wallemia sebi, are among the most xerophilic organisms described. Their morphological adaptations to life at high NaCl concentrations are reflected in increased cell-wall thickness and size of cellular aggregates. The objectives of this study were to examine their growth and to define cell morphology and any ultrastructural cell-wall changes when these fungi are grown in low and high glucose and honey concentrations, as environmental osmolytes. We analysed their growth parameters and morphological characteristics by light microscopy and transmission and scanning electron microscopy. Wallemia ichthyophaga grew slowly in all of the sugar-based media, while W. muriae and W. sebi demonstrated better growth. Wallemia ichthyophaga adapted to the high glucose and honey concentrations with formation of larger cellular aggregates, while cell-wall thickness was increased only at the high glucose concentration. Wallemia muriae and W. sebi demonstrated particularly smaller sizes of hyphal aggregates at the high glucose concentration, and different and less explicit changes in cell-wall thickness. Adaptive responses show that the phylogenetically more distant W. ichthyophaga is better adapted to high salt conditions, whereas W. muriae and W. sebi cope better with a high sugar environment.

Kralj Kun?i? M; Zajc J; Drobne D; Pipan Tkalec Z; Gunde-Cimerman N

2013-07-01

164

Mobil-Badger technologies for benzene reduction in gasoline  

Energy Technology Data Exchange (ETDEWEB)

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

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

1993-01-01

165

Nonlinear diffusion in Acetone-Benzene Solution  

CERN Multimedia

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

Obukhovsky, Vjacheslav V

2010-01-01

166

Hematotoxicity and carcinogenicity of benzene  

Energy Technology Data Exchange (ETDEWEB)

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

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

1989-07-01

167

Occupational exposure to benzene and changes in hematological parameters and urinary trans, trans-muconic acid.  

UK PubMed Central (United Kingdom)

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.

Tunsaringkarn T; Soogarun S; Palasuwan A

2013-01-01

168

Steel corrosion in anoxic mediums with high chloride concentrations  

International Nuclear Information System (INIS)

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

2008-01-01

169

Dilute acid pretreatment of biomass at high acid concentrations  

Energy Technology Data Exchange (ETDEWEB)

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

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

1986-01-01

170

Dielectric Relaxation of Polar Molecules in Benzene Medium at Microwave  

Directory of Open Access Journals (Sweden)

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

S. B. Gedam; B. M. Suryavanshi

2013-01-01

171

Viscosity analysis of high concentration bovine serum albumin aqueous solutions.  

UK PubMed Central (United Kingdom)

PURPOSE: To understand the apparent inconsistency between the dilute and high concentration viscosity behavior of bovine serum albumin (BSA). METHOD: Zeta potential and molecular charge on BSA were determined from Electrophoretic mobility measurements. Second virial coefficient (B(22)) and interaction parameter (k(D)) obtained from static and dynamic light scattering, respectively, quantified intermolecular interactions. Rheology studies characterized viscoelasticity at high concentration. The dipole moment was calculated using Takashima's approximation for proton fluctuations over charged residues. RESULTS: The effective isoelectric point of BSA was pH 4.95. In dilute solutions (? 40 mg/ml), the viscosity was minimal at the pI; at high concentrations, pH 5.0 solutions were most viscous. B(22) and k(D) showed intermolecular attractions at pH 5.0; repulsions dominated at other pHs. The attractive interactions led to a high storage modulus (G') at pH 5.0. CONCLUSION: In dilute solutions, the electroviscous effect due to net charge governs the viscosity behavior; at high concentrations, the solution viscosity cannot be justified based on a single parameter. The net interplay of all intermolecular forces dictates viscosity behavior, wherein intermolecular attraction leads to a higher solution viscosity.

Yadav S; Shire SJ; Kalonia DS

2011-08-01

172

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

Energy Technology Data Exchange (ETDEWEB)

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

Pride, C

1994-08-01

173

[Epidemiological study of cytopenia among benzene-exposed workers and its influential factors].  

UK PubMed Central (United Kingdom)

OBJECTIVE: To evaluate the benzene exposure level and cytopenia among the benzene exposed workers in Shanghai, China and to analyze the influential factors for the health of benzene-exposed workers. METHODS: A total of 3314 benzene-exposed workers, who were from 85 benzene-related enterprises selected by stratified random sampling based on enterprise sizes and industries, were included in the study. The time-weighted average (TWA) concentration of benzene in each workshop was measured by individual sampling and fixed point sampling, and the benzene exposure level in workshop was evaluated accordingly. The occupational health examination results and health status of benzene-exposed workers were collected. RESULTS: The median of TW A concentrations of benzene was 0.3 mglm3• The TWA concentrations measured at 7 ( 1.4%) of the 504 sampling points were above the safety limit. Of the 7 points, 3 were from large enterprises, 2 from medium enterprises, and 2 from small enterprises; 3 were from shipbuilding industry, 1 from chemical industry, and 3 from light industry. Of the 3314 benzene-exposed workers, 451 ( 13.6%) had cytopenia, including 339 males ( 339/2548, 13.3%) and 112 females ( 112/766, 14.6% ). There were significant differences in the incidence rates of leukopenia and neutropenia among the benzene-exposed workers of different sexes and ages (P<0.05); there were significant differences in the incidence rate of cytopenia among the benzene-exposed workers of different ages and working years ( P<0.05 ); there were significant differences in the incidence of neutropenia among the benzene exposed workers of different working years ( P<0.05). CONCLUSION: Monitoring and intervention measures should be enhanced to protect the benzene-exposed workers in the large enterprises in shipbuilding industry and medium and private enterprises in chemical industry from occupational hazards.

Peng JJ; Liu MX; Yang F; Guo WW; Zhuang R; Jia XD

2013-03-01

174

Stability of human telomere quadruplexes at high DNA concentrations.  

UK PubMed Central (United Kingdom)

For mimicking macromolecular crowding of DNA quadruplexes, various crowding agents have been used, typically PEG, with quadruplexes of micromolar strand concentrations. Thermal and thermodynamic stabilities of these quadruplexes increased with the concentration of the agents, the rise depended on the crowder used. A different phenomenon was observed, and is presented in this paper, when the crowder was the quadruplex itself. With DNA strand concentrations ranging from 3 µM to 9 mM, the thermostability did not change up to ~2 mM, above which it increased, indicating that the unfolding quadruplex units were not monomolecular above ~2 mM. The results are explained by self-association of the G-quadruplexes above this concentration. The ?G°37 values, evaluated only below 2 mM, did not become more negative, as with the non-DNA crowders, instead, slightly increased. Folding topology changed from antiparallel to hybrid above 2 mM, and then to parallel quadruplexes at high, 6-9 mM strand concentrations. In this range, the concentration of the DNA phosphate anions approached the concentration of the K(+) counterions used. Volume exclusion is assumed to promote the topological changes of quadruplexes toward the parallel, and the decreased screening of anions could affect their stability. © 2013 Wiley Periodicals, Inc. Biopolymers, 2013.

Kejnovská I; Vorlí?ková M; Brázdová M; Sagi J

2013-08-01

175

Benzene removal by a novel modification of enhanced anaerobic biostimulation.  

UK PubMed Central (United Kingdom)

A novel modification of enhanced anaerobic bioremediation techniques was developed by using non-activated persulfate to accelerate the organic phosphorus breakdown and then stimulate benzene biodegradation by nitrate and sulfate reduction. Benzene concentrations in groundwater where nitrate, triethyl phosphate and persulfate were successfully injected were reduced at removal efficiencies greater than 77% to the levels below the applicable guideline. Soil benzene was removed effectively by the modification of the enhanced anaerobic bioremediation with removal efficiencies ranging between 75.9% and 92.8%. Geochemical analytical results indicated that persulfate effectively breaks down triethyl phosphate into orthophosphate, thereby promoting nitrate and sulfate utilization. Microbial analyses (quantitative polymerase chain reaction, denaturing gradient gel electrophoresis and 16S ribosomal RNA) demonstrated that benzene was primarily biodegraded by nitrate reduction while sulfate reduction played an important role in benzene removal at some portions of the study site. Enrichment in the heavier carbon isotope ¹³C of residual benzene with the increased removal efficiency provided direct evidence for benzene biodegradation. Nitrogen, sulfur and oxygen isotope analyses indicated that both nitrate reduction and sulfate reduction were occurring as bioremediation mechanisms.

Xiong W; Mathies C; Bradshaw K; Carlson T; Tang K; Wang Y

2012-10-01

176

High estrogen concentrations in receiving river discharge from a concentrated livestock feedlot.  

UK PubMed Central (United Kingdom)

Environmental estrogenic chemicals interrupt endocrine systems and generate reproductive abnormalities in wildlife, especially natural and synthetic estrogenic steroid hormones such as 17beta-estradiol (E2), estrone (E1), estriol (E3), 17alpha-ethynylestradiol (EE2), and diethylstilbestrol (DES). Concentrated animal feedlot operations (CAFOs) are of particular concern since large amounts of naturally excreted estrogens are discharged into aquatic environments. This study investigated E2, E1, E3, EE2, and DES with high performance liquid chromatography/tandem mass (HPLC-MS/MS) analyses along Wulo Creek in southern Taiwan, near a concentrated livestock feedlot containing 1,030,000 broiler chickens, 934,000 laying hens, 85,000 pigs, and 1500 cattle. Sampling was performed from December 2008 to May 2009, in which 54 samples were collected. Experimental results indicate that concentrations of EE2 were lower than the limit of detection (LOD), and concentrations of DES were only detected twice. Concentrations ranged from 7.4 to 1267 ng/L for E1, from not detected (ND) to 313.6 ng/L for E2, and from ND to 210 ng/L for E3. E1 had the highest average mass fraction (72.2 + or - 3.6%), which was significantly higher than E3 (16.2 + or - 1.7%) and E2 (11.5 + or - 2.6%). Additionally, the mean E2 equivalent quotient (EEQ) ranged from 17.3 to 137.9 ng-E2/L. Despite having a markedly lower concentration than E1, E2 more significantly contributed (52.4 + or - 6.0%) EEQ than E1 (19.7 + or - 3.5%). Moreover, the concentrations of E2, E1, and E3 upstream were significantly higher than concentrations downstream, suggesting a high attenuation effect and fast degradation in the study water. Most concentrations in winter season were higher than those of spring season due to the low dilution effect and low microbial activity in the winter season. Based on the results of this study, we recommend further treatment of the wastewater discharge from the feedlot.

Chen TS; Chen TC; Yeh KJ; Chao HR; Liaw ET; Hsieh CY; Chen KC; Hsieh LT; Yeh YL

2010-07-01

177

Linear and nonlinear optical properties of highly concentrated gold nanoparticles  

Science.gov (United States)

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

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

2013-08-01

178

Protein Concentrate from High-Protein Pearl Millet.  

Science.gov (United States)

Procedures are described for obtaining about 80% of the high-grade protein in pearl millet grain as a concentrate. These procedures involve extraction of lipid-free whole millet flour with a combination of 70% aqueous isopropyl alcohol, aqueous sodium hyd...

A. V. Bailey G. Sumrell

1980-01-01

179

Development of high-concentration coal slurry technology  

Energy Technology Data Exchange (ETDEWEB)

The principles are outlined involved in the attainment of high concentrations of coal in slurry form and brief details are given of slurry properties, production processes, combustion characteristics and related combustion technology. The use of coal-water slurries as fuel is evaluated. 3 references.

Terada, H.; Masamichi, K.; Shima, T.; Ohtsuka, Y.

1985-01-01

180

Beryllium-10 concentrations in water samples of high northern latitudes  

Energy Technology Data Exchange (ETDEWEB)

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

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

1997-09-01

 
 
 
 
181

High concentration diffusion of P in Si : a percolation problem ?  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A new model is developed for the high concentration diffusion of phosphorus in silicon : it is shown that the accelerated diffusion in the surface region is due to vacancy percolation between the impurities. The corresponding numerical simulation for a 1 000 °C diffusion is in excellent agreement wi...

Mathiot, D.; Pfister, J.C.

182

Process for producing high-concentration slurry of coal  

Energy Technology Data Exchange (ETDEWEB)

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

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

1985-02-19

183

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

Energy Technology Data Exchange (ETDEWEB)

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

Steven B. Hawthorne

2007-04-15

184

Effect of intrinsic properties of metals on the adsorption behavior of molecules: benzene adsorption on Pt group metals.  

UK PubMed Central (United Kingdom)

Investigation of benzene adsorption on different metal surfaces closer to a practical system appears to be a very important intermediate stage to utilize the conclusion obtained on single-crystal surfaces. In this paper, we studied the electrochemical adsorption behaviors of benzene on roughened Pt group electrodes using surface enhanced Raman spectroscopy (SERS). The effects of potential, surface roughness, and benzene concentration were investigated. Significant difference in surface Raman spectra of benzene on Ru, Rh, Pd, and Pt surfaces were found. On Pt surfaces, the parallel-chemisorbed benzene, the vertical dissociated chemisorbed benzene, and the physisorbed benzene were observed, evidenced by the ring vibration mode appearing at 872, 1012, and 991 cm(-1), respectively. On Pd, only parallel-chemisorbed benzene and physisorbed benzene were found. On Rh and Ru, the SERS signals were mainly from the parallel-chemisorbed benzene, with an extremely weak signal from the physisorbed benzene. The potential dependent study reveals that the parallel-chemisorbed species interacts strongest with the substrate, while the physisorbed species can be easily removed at positive potentials. The models for the adsorbed benzene were given to account for the different types of benzene on these Pt group metals. The difference in the atomization heat of the four metals was used to interpret the different interaction strength of benzene with Pt group metals.

Liu GK; Ren B; Wu DY; Duan S; Li JF; Yao JL; Gu RA; Tian ZQ

2006-09-01

185

Prediction of high pressure solid-liquid equilibria for benzene-cyclohexane system based on the van der Waals types of equation of state; Van der Waals gata jotai hoteishiki ni motozuku benzene-cyclohexane kei no koatsu koeki heiko no suisan  

Energy Technology Data Exchange (ETDEWEB)

In order to develop a method for calculating high-pressure solid-liquid equilibria (SLE) for simple eutectic organic compound mixtures, we tested the applicability of the method using equations of state for both liquid and solid phases. By applying two van der Waals types of equation of state to liquid phase, the effect of equation of state for liquid phase on the prediction of high-pressure SLE was investigated. The two equations of state used for liquid phase were the Carnahan-Starling-van der Waals equation (CS-vdW equation) with a hard sphere fluid as a reference system and the Boublik-van der Waals equation (B-vdW equation) with a hard convex body fluid as a reference system. For calculation of molar volume of solid phase, a simple linear pressure dependence equation was assumed. High-pressure SLE for the benzene-cyclohexane system was selected as a simple eutectic model system, since the physical significance of the parameters in the equations of state can be well defined for the two constituting compounds, and accurate experimental data for high-pressure SLE were reported. It was found that both the CS-vdW and B-vdW equations can predict SLE with almost the same accuracy in the composition range where benzene crystallizes, while the CS-vdW equation can predict better than the B-vdW equation in the composition range where cyclohexane crystallizes. The accuracy for representation of PVT relationships for liquid phase with equation of state was found to correlate well with the accuracy of high-pressure SLE prediction. It should be noted that for high-pressure SLE prediction, it is inevitable that accurate equation of state be available. 36 refs., 4 figs., 6 tabs.

Yokoyama, C.; Morita, S.; Ebina, T. [Tohoku University, Sendai (Japan). Institute for Chemical Reaction Science

1998-03-01

186

On the concentration structure of high-concentration constant-volume fluid mud gravity currents  

Science.gov (United States)

An exhaustive laboratory experimental campaign was undertaken in order to elucidate the concentration structure of two-dimensional constant-volume non-Newtonian fluid mud gravity currents. Two sets of experiments were conducted in a lock-exchange tank. The first set of experiments involved measuring the vertical concentration profiles using a siphoning technique; the second set involved auxiliary visual observations. The first set of experiments consisted of 32 experimental runs for four different experimental conditions, with an array of siphoned samples being withdrawn throughout the head and body of the gravity current. From these samples, vertical concentration profiles occurring in constant-volume fluid mud gravity currents were classified and the underlying physical processes that led to the occurrence of observed profiles were discussed. Furthermore, the functional form of the vertical concentration profiles within the head of relatively low-initial-concentration gravity currents was proposed. The relatively high-initial-concentration gravity currents revealed the presence of a lutocline in the current head and body, the presence of which was observed for constant-flux release gravity currents. To our knowledge, this is the first measurement of a lutocline in constant-volume gravity currents. Abrupt transitions, a phenomenon in which the bulk of the suspended sediment in the propagating gravity current drops out, were observed through the concentration profiles and through 15 auxiliary visual experimental runs. It was found that abrupt transitions were caused by the presence of a lutocline. The entrainment of ambient water resulting in the dilution of the gravity current at different concentration contours has been quantified. In a previous work by the authors of this study, it was shown that the initial reduced gravity is directly proportional to the growth rate of the visual area of the two-dimensional current. The analysis of our experimental observations presented in this study, however, showed the initial reduced gravity to be inversely proportional to the growth rate of the area enclosed by concentration contours with higher values than that of the visual area. These seemingly opposing conclusions are rationalized and the considerable practical impacts are discussed.

Jacobson, M. R.; Testik, F. Y.

2013-01-01

187

Unusually high indoor radon concentrations from a giant rock slide.  

UK PubMed Central (United Kingdom)

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

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

1994-07-01

188

Urban benzene pollution and population exposure  

Energy Technology Data Exchange (ETDEWEB)

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

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

2001-07-01

189

Chitosan macroporous foams obtained in highly concentrated emulsions as templates.  

Science.gov (United States)

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

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

2013-08-12

190

Chitosan macroporous foams obtained in highly concentrated emulsions as templates.  

UK PubMed Central (United Kingdom)

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

Miras J; Vílchez S; Solans C; Esquena J

2013-11-01

191

High-flux characterization of ultrasmall multijunction concentrator solar cells  

Science.gov (United States)

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

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

2007-08-01

192

Potential metallurgical treatment of copper concentrates with high arsenic contents  

Scientific Electronic Library Online (English)

Full Text Available Abstract in english SYNOPSIS This paper investigates a potential method for arsenic removal from copper concentrates using hypochlorite leaching. The problems concerning pyrometallurgical processing of copper concentrates with high arsenic contents are discussed. A possible solution to the problem by leaching of natural enargite crystals with sodium hypochlorite under alkaline oxidizing conditions, with enargite converted into crystalline CuO and the soluble arsenic forming AsO4(3-), was exp (more) erimentally 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 (?).

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

2011-06-01

193

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

UK PubMed Central (United Kingdom)

Abstract A framework of "Common Criteria" (i.e. a series of questions) has been developed to inform the use and evaluation of biomonitoring data in the context of human exposure and risk assessment. The data-rich chemical benzene was selected for use in a case study to assess whether refinement of the Common Criteria framework was necessary, and to gain additional perspective on approaches for integrating biomonitoring data into a risk-based context. The available data for benzene satisfied most of the Common Criteria and allowed for a risk-based evaluation of the benzene biomonitoring data. In general, biomarker (blood benzene, urinary benzene and urinary S-phenylmercapturic acid) central tendency (i.e. mean, median and geometric mean) concentrations for non-smokers are at or below the predicted blood or urine concentrations that would correspond to exposure at the US Environmental Protection Agency reference concentration (30?µg/m(3)), but greater than blood or urine concentrations relating to the air concentration at the 1?×?10(-5) excess cancer risk (2.9?µg/m(3)). Smokers clearly have higher levels of benzene exposure, and biomarker levels of benzene for non-smokers are generally consistent with ambient air monitoring results. While some biomarkers of benzene are specific indicators of exposure, the interpretation of benzene biomonitoring levels in a health-risk context are complicated by issues associated with short half-lives and gaps in knowledge regarding the relationship between the biomarkers and subsequent toxic effects.

Arnold SM; Angerer J; Boogaard PJ; Hughes MF; O'Lone RB; Robison SH; Schnatter AR

2013-02-01

194

High Actin Concentrations in Brain Dendritic Spines and Postsynaptic Densities  

Science.gov (United States)

Antibodies against actin were used to corroborate the presence of actin as a major component protein of isolated brain postsynaptic densities. The same antibodies also were used as an immunohistochemical stain to study the distribution of actin in sections of intact brain tissue. This showed two major sites where actin is concentrated: smooth muscle cells around blood vessels and postsynaptic sites. In the postsynaptic area the highest concentration of actin occurs in postsynaptic densities and there also is intense staining in the surrounding cytoplasm, especially within dendritic spines. Antiactin staining was much weaker in other parts of neurons and in glial cells. The high concentration of actin in dendritic spines may be related to shape changes that these structures have been found to undergo in response to prolonged afferent stimulation.

Matus, Andrew; Ackermann, Marcel; Pehling, Gundula; Randolph Byers, H.; Fujiwara, Keigi

1982-12-01

195

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

International Nuclear Information System (INIS)

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

2006-01-01

196

Particle characterisation in highly concentrated dispersions using ultrasonic backscattering method.  

UK PubMed Central (United Kingdom)

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

Weser R; Wöckel S; Wessely B; Hempel U

2013-03-01

197

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.

2000-01-01

198

CULTURE METHOD FOR HIGH CONCENTRATION OF THIOCAPSA RESEOPERSICINA  

UK PubMed Central (United Kingdom)

A culture method for high concentration of Thiocapsa roseopersicina is provided to maximize the growth of cells under photo-autotrophic conditions, so that a large quantity of hydrogenase is produced. A high concentration of Thiocapsa roseopersicina NCIB 8347 is photo-autotrophically cultured in a medium containing acetate as a carbon source under the carbon dioxide-containing nitrogen condition at 26 deg. C for 3-5 days, wherein the medium further contains ammonium chloride and a trace amount of elements including Na2S.9H2O, Na2.EDTA, FeSO4.7H2O, CoCl2.6H2O, MnCl2.2H2O, ZnCl2, NiCl2.6H2O, Na2MoO4.2H2O, H3BO3 and CuCl2.2H2O.

KIM MI SUN; OH YOU KWAN

199

Materials balance for benzene: Level II. Final report  

Energy Technology Data Exchange (ETDEWEB)

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

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

1980-05-01

200

Highly concentrated emulsions. Physicochemical principles of the preparation and stability  

International Nuclear Information System (INIS)

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

2008-08-31

 
 
 
 
201

Highly concentrated emulsions. Physicochemical principles of the preparation and stability  

Energy Technology Data Exchange (ETDEWEB)

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

Babak, V G [A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Moscow (Russian Federation)

2008-08-31

202

Biodegradation studies of oil sludge containing high hydrocarbons concentration  

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-07-01

203

Biodegradation studies of oil sludge containing high hydrocarbons concentration  

International Nuclear Information System (INIS)

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

2008-09-00

204

Achieving High Dopant Concentrations in Si: First Principles Simulations  

Energy Technology Data Exchange (ETDEWEB)

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

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

2002-08-12

205

Living with high concentrations of urea: They can!  

Directory of Open Access Journals (Sweden)

Full Text Available Marine elasmobranchs maintain their body fluid isoosmotic or slightly hyperosmotic to the external medium by the retention of large urea concentrations. This review focuses on the strategies adopted by these fishes to maintain a large outwardly direct concentration gradient of this osmolyte minimizing the loss across the main interfaces between body fluid and the external medium such as the gills, the kidney and the rectal gland, thus reducing the cost of making urea. The high plasma osmolarity, mainly main-tained by urea retention, is a challenge to volume homeostasis when fish move from seawater to water with a low salinity, since the high water permeability of branchial epithelium would cause a net flux of water into the animal. Since the renal regulation of urea retention in habitat with different salinities is crucial for the osmotic homeostasis of these species, the regulation of the activity and/or the expression of urea trans porters in renal tubules will be also discussed. In addition attention will be paid on the urea– methylamine system involved in maintaining the stability and functioning of many proteins since it is known that the high urea concentration found in marine elasmobranch fish, similar only to that found in mammalian kidney, has a destabilizing effect on many macromolecules and inhibits functions such as ligand binding.

Francesca Trischitta; Caterina Faggio; Agata Torre

2012-01-01

206

Thermodynamic limits to microbial life at high salt concentrations.  

UK PubMed Central (United Kingdom)

Life at high salt concentrations is energetically expensive. The upper salt concentration limit at which different dissimilatory processes occur in nature appears to be determined to a large extent by bioenergetic constraints. The main factors that determine whether a certain type of microorganism can make a living at high salt are the amount of energy generated during its dissimilatory metabolism and the mode of osmotic adaptation used. I here review new data, both from field observations and from the characterization of cultures of new types of prokaryotes growing at high salt concentrations, to evaluate to what extent the theories formulated 12 years ago are still valid, need to be refined, or should be refuted on the basis of the novel information collected. Most data agree well with the earlier theories. Some new observations, however, are not easily explained: the properties of Natranaerobius and other haloalkaliphilic thermophilic fermentative anaerobes, growth of the sulfate-reducing Desulfosalsimonas propionicica with complete oxidation of propionate and Desulfovermiculus halophilus with complete oxidation of butyrate, growth of lactate-oxidizing sulfate reducers related to Desulfonatronovibrio at 346 g l(-1) salts at pH 9.8, and occurrence of methane oxidation in the anaerobic layers of Big Soda Lake and Mono Lake.

Oren A

2011-08-01

207

Thermodynamic limits to microbial life at high salt concentrations.  

Science.gov (United States)

Life at high salt concentrations is energetically expensive. The upper salt concentration limit at which different dissimilatory processes occur in nature appears to be determined to a large extent by bioenergetic constraints. The main factors that determine whether a certain type of microorganism can make a living at high salt are the amount of energy generated during its dissimilatory metabolism and the mode of osmotic adaptation used. I here review new data, both from field observations and from the characterization of cultures of new types of prokaryotes growing at high salt concentrations, to evaluate to what extent the theories formulated 12 years ago are still valid, need to be refined, or should be refuted on the basis of the novel information collected. Most data agree well with the earlier theories. Some new observations, however, are not easily explained: the properties of Natranaerobius and other haloalkaliphilic thermophilic fermentative anaerobes, growth of the sulfate-reducing Desulfosalsimonas propionicica with complete oxidation of propionate and Desulfovermiculus halophilus with complete oxidation of butyrate, growth of lactate-oxidizing sulfate reducers related to Desulfonatronovibrio at 346 g l(-1) salts at pH 9.8, and occurrence of methane oxidation in the anaerobic layers of Big Soda Lake and Mono Lake. PMID:21054738

Oren, Aharon

2010-11-05

208

Improved Dispersion of Carbon Nanotubes in Polymers at High Concentrations  

Directory of Open Access Journals (Sweden)

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.

Chao-Xuan Liu; Jin-Woo Choi

2012-01-01

209

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

Energy Technology Data Exchange (ETDEWEB)

The changes of O-Ps intensity in benzene and cyclohexane solutions in the presence of different concentrations of electron scavenger (CCl/sub 4/) and positive hole scavenger (pyridine) have been investigated. The results show that mobilities of both electron and positive ion in cyclohexane are very high. Their mobilities in benzene are also high but less than that in cyclohexane. The fitting equation for the enhancement of O-Ps intensity in the presence of hole scavenger was derived, which shows that enhancement or inhibition of O-Ps intensity are consequences of the competition of the two processes of scavenging electron and scavenging positive ion. The absolute amount of enhancement of O-Ps intensity is not only related to the scavenging rate but also to the O-Ps intensity in pure positive hole scavenger.

Man-Wei, Z.; Wen-Yuan, W. (University of Science and Technology of China, Hefei)

1982-01-01

210

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

International Nuclear Information System (INIS)

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

1982-01-01

211

Benzene Sensing Using Thin Films of Titanium Dioxide Operating at Room Temperature  

Directory of Open Access Journals (Sweden)

Full Text Available Benzene is a carcinogen with a maximum permitted exposure limit in the atmosphere of 16.25μg m-3 (5 ppb). There is a need for an inexpensive instrument for measuring benzene concentrations, particularly in urban areas. We have shown that thin films of titanium dioxide dispersed in poly(vinylidenfluoride) are sensitive to benzene at room temperature with possible applications in benzene monitors. In this paper, we present a detailed study into the direct current electrical characteristics of the films when exposed to benzene. The current I through the films increase linearly with applied voltage, V, at low applied voltages (V ≲0.6V) and at higher voltages, I α V5. The results are consistent with the films being p-type semiconductors and, at higher voltages, the conduction is dominated by a space charge limited process caused by negative traps with an average energy of 0.1 eV. The films are sensitive to benzene only at the higher voltages. The proposed mechanism is that benzene molecules on the surface of the films reduce the concentration of holes. The relative resistance of the films increases linearly (r = 0.92) with benzene concentrations (sensitivity of 0.042% ppm-1) and a detection limit of 10 ppm. The films have response times to increasing and decreasing concentrations of benzene of about 1 and 5 min respectively.

Mohammed Mabrook; Peter Hawkins

2002-01-01

212

REFORMATE BENZENE REDUCTION VIA TRANSALKYLATION  

UK PubMed Central (United Kingdom)

A process for reducing benzene content in a reformate stream, including: fractionating a full range reformate comprising benzene, C7 to C9 monoalkyl aromatics, and C1O+ polyalkyl aromatics into at least three fractions including a light reformate fraction comprising the benzene a medium reformate fraction comprising the C7 to C9 monoalkyl aromatics and a heavy reformate fraction comprising the C10+ polyalkyl aromatics feeding the light reformate fraction, the heavy reformate fraction and a transalkylation catalyst to a transalkylation reaction zone contacting the light fraction and the heavy fraction in presence of the transalkylation catalyst in the transalkylation reaction zone to react at least a portion of the benzene with C1O+ polyalkyl aromatics to form monoalkyl aromatics separating an effluent from the transalkylation reaction zone to form a catalyst fraction and a liquid fraction comprising the monoalkyl aromatics.

ROCK KERRY L; BOYER CHRISTOPHER C; SMITH LAWRENCE A

213

[Effect of immobilization on biosensor for benzene derivates detection].  

UK PubMed Central (United Kingdom)

A whole cell sensor, Pseudomonas fluorescens A506 (pTS), was immobilized by sodium alginate and the factors of cell density, immobilization time and beads usage were optimized. The performance of the immobilized cells was compared with that of the free cells. After 2 h immobilization,the increasing speed of fluorescent signal of immobilized cells was 2.26 times as high as that of the free cells,and the peak value was 2.23 times as high during the detection time ranging from 1.5 to 6.0 h. The constantly lower growth and density of the immobilized cell implied the enhanced signal intensity of single cells after immobilization. Meanwhile, the cell density decreased as the immobilization time prolonged. Cell density and immobilization time were the dominant factors affecting the detection signal. For benzene at higher concentrations, the immobilized biosensor showed more rapid signal response at the early period of detection.

Tang K; Ma AZ; Yu Q; Deng XM; Lü D; Zhuang GQ

2013-02-01

214

[Evaluation of total exposure to benzene and formaldehyde in the European countries].  

Science.gov (United States)

Benzene and formaldehyde are among the principal components in the air of various indoor occupational and non-occupational environments. Both compounds are toxicologically relevant for humans as recognized carcinogens. In order to evaluate the total exposure and to assess the possible health risk caused by benzene and formaldehyde for different population groups at European level, the JRC Institute for Health and Consumer Protection in Ispra launched the AIRMEX (IndoorAir Monitoring and ExposureAssessment Study) project in October 2003. It aims at identifying and quantifying the main indoor pollutants particularly in kindergartens, schools and public buildings. It also intends to evaluate the overall exposure of people working and occupying these areas. Measuring campaigns were carried out in pre-selected indoor environments in various European cities (Catania, Athens, Arnhem, Nijmegen, Brussels, Thessaloniki). Preliminary results clearly indicate that indoor air concentrations for volatile compounds (VOC) including benzene are higher than/or similar to those found outdoors, ranging from a few micrograms (about 8 microg/m3) to 281 microg/m3. Outdoor concentrations vary from 7 to 153 microg/m3. Personal exposure concentrations are generally higher than the indoor/outdoor concentrations. In most cases they are twice as high as indoor concentrations (or even higher) and significantly higher than outdoor concentrations. Air concentrations of aldehydes inside buildings/kindergartens were up to 7-8 times higher than outside. This mostly concerns formaldehyde, and it seems that strong indoor sources exist which clearly determine the indoor air concentrations. Formaldehyde concentrations in public buildings and offices vary from 3 to 30 microg/m3, and those in kindergartens vary from 6 to 11 microg/m3 (Arnhem/Nijmegen). The highest values for formaldehyde, up to 29,9 microg/m3, were found in Catania, Athens and Thessaloniki. PMID:16646255

Kotzias, Dimitrios; Geiss, Otmar; Tirendi, Salvatore

215

Organoclay formulations of acetochlor: effect of high salt concentration.  

UK PubMed Central (United Kingdom)

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

El-Nahhal Y; Lagaly G; Rabinovitz O

2005-03-01

216

Organoclay formulations of acetochlor: effect of high salt concentration.  

Science.gov (United States)

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

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

2005-03-01

217

Practical design constraints for using secondary concentrators at high temperatures  

Energy Technology Data Exchange (ETDEWEB)

The optical advantages of using nonimaging secondary concentrators in two-stage solar thermal dish systems are well understood. However, practical questions having to do with the thermal behavior of any secondary and its possible effects on the performance of cavity type receivers have only recently begun to be investigated. A few years ago an experimental demonstration of a trumpet type nonimaging secondary concentrator was carried out with a cavity receiver operating 660 C in combination with the Cummins Power Generation CPG-460 7.5 kWe concentrator system. Lessons learned from this and previous experiments are reviewed. The tests alleviated any operational concerns about the effectiveness of active water cooling and have shown that secondaries can be operated successfully at high temperatures without significant problems. There was no evidence of direct heat loss from the hot receiver to the cooled trumpet. The optical quality of any primary can be expected to fall well below design goals and to deteriorate further with time. This expectation should be taken into account in planning future experiments and developing new concentrating systems.

O' Gallagher, J.J.; Winston, R.

1999-07-01

218

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

Science.gov (United States)

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

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

2010-10-25

219

Strategies for the production of high concentrations of bioethanol from seaweeds: production of high concentrations of bioethanol from seaweeds.  

UK PubMed Central (United Kingdom)

Bioethanol has attracted attention as an alternative to petroleum-derived fuel. Seaweeds have been proposed as some of the most promising raw materials for bioethanol production because they have several advantages over lignocellulosic biomass. However, because seaweeds contain low contents of glucans, i.e., polysaccharides composed of glucose, the conversion of only the glucans from seaweed is not sufficient to produce high concentrations of ethanol. Therefore, it is also necessary to produce ethanol from other specific carbohydrate components of seaweeds, including sulfated polysaccharides, mannitol, alginate, agar and carrageenan. This review summarizes the current state of research on the production of ethanol from seaweed carbohydrates for which the conversion of carbohydrates to sugars is a key step and makes comparisons with the production of ethanol from lignocellulosic biomass. This review provides valuable information necessary for the production of high concentrations of ethanol from seaweeds.

Yanagisawa M; Kawai S; Murata K

2013-07-01

220

Decomposition of benzene in a corona discharge at atmospheric pressure  

International Nuclear Information System (INIS)

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

2008-05-01

 
 
 
 
221

Preparation method of high-concentration malt wort  

UK PubMed Central (United Kingdom)

The invention relates to a preparation method of high-concentration malt wort, which comprises the following steps of: boiling the filtered malt wort in a boiler adding syrup for beer prepared from starch by specific processes and hydrolysis of multiple enzyme preparations in a mash boiler in advance before the boiling process is finished and then, depositing by rotating and cooling the hot malt wort mixed by the boiler to obtain the high-concentration malt wort. The malt wort of the invention has short preparation period and short conversion time, thereby greatly improving the efficiency for converting starch into syrup. In addition, specific starch decomposition processes are adopted by the invention, the step of secondary liquefaction is increased, and the syrup converted by the compounding technology of three kinds of amylolytic enzyme preparations meets the requirements of beer brewing, thus a brewery can save the transportation cost of syrup purchase and a large amount of energy consumption in the processes of preparation and concentration of bought-in syrup. Meanwhile, the syrup for beer brewing, which is prepared from starch, is directly added into the boiler and does not need to participate in the whole process of boiling malt wort, thereby reducing the production cost of beer malt wort, and saving the energy consumption.

ZONGMING CHANG; LIANJU SHAN; JIANJUN DONG; WEI FAN; GANG LIANG; XIAOHONG LOU; XIANGRONG PI; KEXIN WANG; MEI YANG; HUA YIN

222

Process for the preparation of ethyl benzene  

Energy Technology Data Exchange (ETDEWEB)

Ethyl benzene is produced in a catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 50.degree. C. to 300.degree. C., using as the catalyst a mole sieve characterized as acidic by feeding ethylene to the catalyst bed while benzene is conveniently added through the reflux to result in a molar excess present in the reactor to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene and diethyl benzene in the bottoms. The bottoms are fractionated, the ethyl benzene recovered and the bottoms are contacted with benzene in the liquid phase in a fixed bed straight pass reactor under conditions to transalkylate the benzene thereby converting most of the diethyl benzene to ethyl benzene which is again separated and recovered.

Smith, Jr., Lawrence A. (Houston, TX); Arganbright, Robert P. (Houston, TX); Hearn, Dennis (Houston, TX)

1995-01-01

223

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2013-06-01

224

Unexpectedly high yield carbon nanotube synthesis from low-activity carbon feedstocks at high concentrations.  

UK PubMed Central (United Kingdom)

We report a new direction for highly efficient carbon nanotube (CNT) synthesis where, in place of conventional highly reactive carbon feedstocks at low concentrations, highly stable carbon feedstocks at high concentrations were shown to produce superior yields. We found that a saturated hydrocarbon that is considered to possess a low reactivity, delivered at high concentrations, could achieve an extremely high growth yield (2.5 times that when using ethylene). This result stems from the unique behavior where the CNT yield linearly increased with carbon concentration, in contrast to more reactive carbon feedstocks, where the yield peaks. We propose that the mechanisms for the growth kinetics for high- and low-reactivity carbon feedstocks are fundamentally different, where the latter benefits from a longer catalyst lifetime because of a relatively low production rate of carbon impurities.

Kimura H; Goto J; Yasuda S; Sakurai S; Yumura M; Futaba DN; Hata K

2013-04-01

225

Liver imaging with MDCT and high concentration contrast media  

International Nuclear Information System (INIS)

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

2003-01-01

226

Synthesis of highly concentrated silver nanoparticles assisted polymeric dispersant.  

Energy Technology Data Exchange (ETDEWEB)

Silver nanoparticles are well known as novel materials as metal electrodes on ceramics, catalyst, antibacterial agent, and etc. The assisted role of polymeric ceramic dispersant on synthesis of highly concentrated silver nanoparticles was studied. The used ceramic dispersants with different kinds of counter ion of polyelectrolyte were polymethylmetacrylic ammonium salt (PMMA, i.e., Darvan C: R.T. Vanderbilt Co.), polyacrylic ammonium salt (PAA), polyacrylic amine salt (PAAm), and polyacrylic sodium salt (PAS). The formation of Ag(0) nanoparticles was followed by UV spectrometer, XRD and TEM. According to TEM investigations Ag(0) nanoparticles with the rage of 10 {proportional_to} 20 nm in diameter were produced. The possible concentration of batch - synthesized silver nanoparticles was up to 10 wt%. (orig.)

Ryu, B.H.; Lee, J.D.; Lee, O.S.; Kang, Y.C.; Park, H.S. [Advanced Materials Div., Korea Research Inst. of Chem. Technology, Taejeon (Korea)

2004-07-01

227

Urinary S-PMA related to indoor benzene and asthma in children.  

UK PubMed Central (United Kingdom)

INTRODUCTION: Benzene is a ubiquitous pollutant of both indoor and outdoor environments which impacts on respiratory health. Our aim was to relate urinary S-phenylmercapturic acid (S-PMA), a biomarker of benzene exposure, to benzene concentrations and related sources at home and asthma in a population-based sample of children. METHODS: Exposure to benzene was assessed in the dwellings of 63 children (32 asthmatics and 31 controls) through the identification of sources of benzene and in situ assessments with passive samplers. The determination of urinary S-PMA was obtained by liquid chromatography-mass spectrometry. RESULTS: At home, asthmatics were significantly more polluted by benzene levels from ambient sampling than controls (p ? 0.05). Benzene exposure significantly aggravated asthma symptoms overall in non-atopic children (OR = 10.10; 95% confidence interval: 10.10). Urinary S-PMA was significantly associated with benzene concentrations in the entire population (regression coefficient = 0.28, 95% CI: 0.07-0.49; p < 0.05) and asthma (OR = 7.69; 95% CI: 1.37-42.52 for an increase of 1 µg/g creatinine of urinary S-PMA). However, after adjustment for environmental tobacco smoking exposure, familial allergy, age and sex, the latter relationship was no more significant (OR = 4.95; 95% CI: 0.91-27.4, p < 0.10). Both benzene concentrations and urinary S-PMA concentrations were higher in dwelling built after 1948 and in flats. CONCLUSIONS: Our study suggests a relationship between childhood asthma and benzene concentrations at home, even at low levels of this pollutant. This was confirmed when considering urinary S-PMA, which was related to both benzene concentrations and asthma. Further epidemiological and toxicological studies are needed to confirm our results.

Rive S; Hulin M; Baiz N; Hassani Y; Kigninlman H; Toloba Y; Caillaud D; Annesi-Maesano I

2013-06-01

228

Mitigation of houses with extremely high indoor radon concentrations  

Energy Technology Data Exchange (ETDEWEB)

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)

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

2006-07-01

229

Low-dose metabolism of benzene in humans: science and obfuscation.  

UK PubMed Central (United Kingdom)

Benzene is a ubiquitous air pollutant that causes human leukemia and hematotoxic effects. Although the mechanism by which benzene causes toxicity is unclear, metabolism is required. A series of articles by Kim et al. used air and biomonitoring data from workers in Tianjin, China, to investigate the dose-specific metabolism (DSM) of benzene over a wide range of air concentrations (0.03-88.9 p.p.m.). Kim et al. concluded that DSM of benzene is greatest at air concentrations <1 p.p.m. This provocative finding motivated the American Petroleum Institute to fund a study by Price et al. to reanalyze the original data. Although their formal 'reanalysis' reproduced Kim's finding of enhanced DSM at sub-p.p.m. benzene concentrations, Price et al. argued that Kim's methods were inappropriate for assigning benzene exposures to low exposed subjects (based on measurements of urinary benzene) and for adjusting background levels of metabolites (based on median values from the 60 lowest exposed subjects). Price et al. then performed uncertainty analyses under alternative approaches, which led them to conclude that '… the Tianjin data appear to be too uncertain to support any conclusions …' regarding the DSM of benzene. They also argued that the apparent low-dose metabolism of benzene could be explained by 'lung clearance.' In addressing these criticisms, we show that the methods and arguments presented by Price et al. are scientifically unsound and that their results are unreliable.

Rappaport SM; Kim S; Thomas R; Johnson BA; Bois FY; Kupper LL

2013-01-01

230

First demonstration of MA recovery from genuine high active concentrate  

International Nuclear Information System (INIS)

Today, U and Pu are industrially reprocessed in the well-established PUREX process, which can be adapted to include also Np recycling. However, the minor actinides (MA), Am and Cm, are not separated and form together with fission products the high level waste fraction of the PUREX process, the so-called high active raffinate (HAR). The present HAR waste management is based on vitrification in a borosilicate glass matrix for final storage. In view of P and T, several extraction processes have been developed world wide for the separation and recovery of Am and Cm from HAR. One of the most promising is the French DIAMEX process, currently further developed in European collaborations, which uses diamides in an organic diluent as solvent. Besides the excellent extraction capabilities, the adaptation to the PUREX process is quite easy and the solvent is completely combustible and yields therefore no solid secondary residues. The combined PUREX - DIAMEX process has previously been successfully demonstrated using genuine HAR fuel solutions. In view of a process industrialisation, the next step has been the development of a DIAMEX process for the recovery of minor actinides from concentrated HAR solutions, the so-called high active concentrate (HAC). The main advantage is the volume reduction - up to 10 times is conceivable - which reduces waste volumes, makes an industrial process more compact and thereby more economic. (orig.)

2004-09-03

231

High-level radon concentrations in the Neapolitan area  

International Nuclear Information System (INIS)

[en] The Neapolitan area is characterized by high levels of natural radiation which occur due to volcanic and tectonic features of the area. Soils from and building materials used in the area (such as tuff and pozzolana) prove to have high levels of radioactive content and hence provide a large contribution to highly significant local indoor radon concentrations and other sources of radioactivity. Although the national and regional surveys carried out in this area over the last few years in order to investigate indoor radon levels produced values not significantly higher than those for other areas of Italy, on the basis of soil characteristics and building materials used in the area, one could expect much higher radon levels to occur. For this reason, we carried out investigations in several houses built using tuff and/or located on a tuff plateau in the historical centre of naples, and in other smaller towns of the region. Although climatic conditions are generally favourable to air exchange between indoors and out, radon hot spots are present, with concentrations of up to 3 - 4 kBq/m3. We aimed to identify such hot spots, in order to be able to identify dwellings with an associated risk of higher levels of radiation dose and health effects. The data presented were obtained using different kinds of detectors. The results obtained allow one to make some interesting observations. (orig.)

2002-01-01

232

High-level radon concentrations in the Neapolitan area  

Energy Technology Data Exchange (ETDEWEB)

The Neapolitan area is characterized by high levels of natural radiation which occur due to volcanic and tectonic features of the area. Soils from and building materials used in the area (such as tuff and pozzolana) prove to have high levels of radioactive content and hence provide a large contribution to highly significant local indoor radon concentrations and other sources of radioactivity. Although the national and regional surveys carried out in this area over the last few years in order to investigate indoor radon levels produced values not significantly higher than those for other areas of Italy, on the basis of soil characteristics and building materials used in the area, one could expect much higher radon levels to occur. For this reason, we carried out investigations in several houses built using tuff and/or located on a tuff plateau in the historical centre of naples, and in other smaller towns of the region. Although climatic conditions are generally favourable to air exchange between indoors and out, radon hot spots are present, with concentrations of up to 3 - 4 kBq/m{sup 3}. We aimed to identify such hot spots, in order to be able to identify dwellings with an associated risk of higher levels of radiation dose and health effects. The data presented were obtained using different kinds of detectors. The results obtained allow one to make some interesting observations. (orig.)

Sabbarese, C.; D' Onofrio, A.; Terrasi, F. [Dipt. di Scienze Ambientali, Seconda Univ. di Napoli, Caserta (Italy); Pugliese, M.; Roca, V.; Vollaro, P. [Dipt. di Scienze Fisiche, Univ. di Napoli ' ' Federico II' ' , Napoli (Italy)

2002-03-01

233

Recovery of uranium from solutions containing high concentration of fluoride  

International Nuclear Information System (INIS)

[en] 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)

1982-01-01

234

Reactions of energetic carbon-11 with benzene leading to acetylene  

International Nuclear Information System (INIS)

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

1987-06-04

235

Status of concentrator collector and high-efficiency concentrator cell development  

Energy Technology Data Exchange (ETDEWEB)

Photovoltaic concentrator collectors are an attractive option for utility-scale photovoltaic power plants. This paper reviews the current status of photovoltaic concentrator collector and cell development. Included in the review is a discussion of the economic motivation for concentrators, a summary of recent concentrator collector and cell development, and a description of a major new program to accelerate development and commercial introduction of concentrator collectors. 21 refs., 1 fig., 3 tabs.

Gee, J.M.

1990-01-01

236

Benzene bioremediation using cow dung microflora in two phase partitioning bioreactor  

International Nuclear Information System (INIS)

[en] 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.

2010-03-15

237

Benzene bioremediation using cow dung microflora in two phase partitioning bioreactor  

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-03-15

238

Hydrogen concentration and distribution in high-purity germanium crystals  

Energy Technology Data Exchange (ETDEWEB)

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 10/sup 15/cm/sup -3/ has been determined by growing crystals in hydrogen spiked with tritium and counting the tritium ..beta..-decays in detectors made from these crystals. Annealing studies show that the hydrogen is strongly bound, either to defects or as H/sub 2/ 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 10/sup 7/ cm/sup -3/ and are estimated to contain 10/sup 8/ H atoms each.

Hansen, W.L.; Haller, E.E.; Luke, P.N.

1981-10-01

239

Shock initiation studies on high concentration hydrogen peroxide  

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-01-01

240

Do high concentrations of microcystin prevent Daphnia control of phytoplankton?  

Science.gov (United States)

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

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

2013-01-18

 
 
 
 
241

Do high concentrations of microcystin prevent Daphnia control of phytoplankton?  

UK PubMed Central (United Kingdom)

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

Chislock MF; Sarnelle O; Jernigan LM; Wilson AE

2013-04-01

242

First DIAMEX partitioning using genuine high active concentrate  

International Nuclear Information System (INIS)

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

2004-01-01

243

Benzene pollution from gasoline usage.  

UK PubMed Central (United Kingdom)

Local gasolines contain benzene ranging from 1.8 to 3.7% and their use can lead to significant exposure to benzene. Gasoline station attendants were found to be exposed to short-term exposure levels (STEL) of 0.064-179 ppm. Their 8-h time-weighted averaged (TWA) exposure ranged from 0.028 to 0.71 ppm. For motorcar service mechanics, TWA exposure levels ranged from 0.014 to 1.7 ppm. The exposure of drivers of gasoline delivery tankers ranged from 0.08 to 2.37 ppm for personal TWA exposure over the whole workshift. For local people not occupationally exposed to gasoline or other benzene-containing volatile chemicals, exposure from the ambient environment ranged from 0.0023 to 0.027 ppm. Gasoline usage also contributed to the contamination of surface water with benzene. Benzene levels in water samples taken from drains leading from gasoline stations were between 1.1 and 40.4 micrograms l-1.

Foo SC

1991-04-01

244

Benzene pollution from gasoline usage  

Energy Technology Data Exchange (ETDEWEB)

Local gasolines contain benzene ranging from 1.8 to 3.7% and their use can lead to significant exposure to benzene. Gasoline station attendants were found to be exposed to short-term exposure levels (STEL) of 0.064-179 ppm. Their 8-h time-weighted averaged (TWA) exposure ranged from 0.028 to 0.71 ppm. For motorcar service mechanics, TWA exposure levels ranged from 0.014 to 1.7 ppm. The exposure of drivers of gasoline delivery tankers ranged from 0.08 to 2.37 ppm for personal TWA exposure over the whole workshift. For local people not occupationally exposed to gasoline or other benzene-containing volatile chemicals, exposure from the ambient environment ranged from 0.0023 to 0.027 ppm. Gasoline usage also contributed to the contamination of surface water with benzene. Benzene levels in water samples taken from drains leading from gasoline stations were between 1.1 and 40.4 microgramme l{sup {minus}1}. 3 figs., 14 refs., 1 tab.

Foo, S.C. (National Univ. of Singapore (Singapore))

1991-04-01

245

Benzene pollution from gasoline usage.  

Science.gov (United States)

Local gasolines contain benzene ranging from 1.8 to 3.7% and their use can lead to significant exposure to benzene. Gasoline station attendants were found to be exposed to short-term exposure levels (STEL) of 0.064-179 ppm. Their 8-h time-weighted averaged (TWA) exposure ranged from 0.028 to 0.71 ppm. For motorcar service mechanics, TWA exposure levels ranged from 0.014 to 1.7 ppm. The exposure of drivers of gasoline delivery tankers ranged from 0.08 to 2.37 ppm for personal TWA exposure over the whole workshift. For local people not occupationally exposed to gasoline or other benzene-containing volatile chemicals, exposure from the ambient environment ranged from 0.0023 to 0.027 ppm. Gasoline usage also contributed to the contamination of surface water with benzene. Benzene levels in water samples taken from drains leading from gasoline stations were between 1.1 and 40.4 micrograms l-1. PMID:1857958

Foo, S C

1991-04-01

246

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

Energy Technology Data Exchange (ETDEWEB)

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

Georgeton, G.K.; Taylor, G.A. [Westinghouse Savannah River Co., Aiken, SC (United States); Gaughan, T.P. [Elf Atochem North America, Inc., King of Prussia, PA (United States)] [and others

1995-06-27

247

Sensitive and selective system of benzene detection based on a cataluminescence sensor.  

UK PubMed Central (United Kingdom)

Au/La2 O3 nanomaterials were prepared through calcining Au-modified La(OH)3 precursors. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffractometry (XRD) were employed to characterize the as-prepared samples. Benzene, a common volatile organic compound, was selected as a model to investigate the cataluminescence (CTL)-sensing properties of the Au/La2 O3 nanomaterials. Results indicated that the as-prepared Au/La2 O3 exhibited outstanding CTL properties such as stable intensity, high signal-to-noise values, and short response and recovery times. Under optimized conditions, the benzene assay exhibited a broad linear range of 1-4000?ppm, with a limit of detection of 0.7?ppm, which was below the standard permitted concentrations. Furthermore, the gas sensor system showed outstanding selectivity for benzene compared with seven other types of common volatile organic compounds (VOCs). The proposed gas sensor showed good characteristics with high selectivity, fast response time and long lifetime, which suggested the promising application of the Au/La2 O3 nanomaterials as a novel highly efficient CTL-sensing material. Copyright © 2013 John Wiley & Sons, Ltd.

Li B; Zhang Y; Liu J; Xie X; Zou D; Li M; Liu J

2013-07-01

248

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

UK PubMed Central (United Kingdom)

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

Peng C; Arthur DM; Sichani HT; Xia Q; Ng JC

2013-09-01

249

High concentration of kynurenic acid in bile and pancreatic juice.  

Science.gov (United States)

Kynurenic acid (KYNA) is an agonist of the G-protein-coupled receptor GPR35, which is predominantly expressed in gastrointestinal tissues. The aim of this study was to determine the content of KYNA in gastric juice, bile and pancreatic juice and intestinal content. KYNA was determined by means of high performance liquid chromatography. The mean concentrations of KYNA in human gastric juice is 9.91 +/- 0.71 nM in contrast to human bile (832.5 +/- 204.1 and 306.8 +/- 35.2 nM) obtained from patients with cholecystolithiasis and obstructive jaundice, respectively. In pigs, the KYNA levels in bile and pancreatic juice are 1,113.3 +/- 63.34 and 757.0 +/- 394.4 nM, respectively. The KYNA concentration increases along the digestive system, reaching 1,638 nM in the colon content. We suggest that the liver and pancreas affect the content of kynurenic acid in the lumen of the digestive tract. PMID:18836681

Paluszkiewicz, Piotr; Zgrajka, Wojciech; Saran, Tomasz; Schabowski, Janusz; Piedra, Jose L Valverde; Fedkiv, Olexandr; Rengman, Sofia; Pierzynowski, Stefan G; Turski, Waldemar A

2008-10-05

250

High concentration of kynurenic acid in bile and pancreatic juice.  

UK PubMed Central (United Kingdom)

Kynurenic acid (KYNA) is an agonist of the G-protein-coupled receptor GPR35, which is predominantly expressed in gastrointestinal tissues. The aim of this study was to determine the content of KYNA in gastric juice, bile and pancreatic juice and intestinal content. KYNA was determined by means of high performance liquid chromatography. The mean concentrations of KYNA in human gastric juice is 9.91 +/- 0.71 nM in contrast to human bile (832.5 +/- 204.1 and 306.8 +/- 35.2 nM) obtained from patients with cholecystolithiasis and obstructive jaundice, respectively. In pigs, the KYNA levels in bile and pancreatic juice are 1,113.3 +/- 63.34 and 757.0 +/- 394.4 nM, respectively. The KYNA concentration increases along the digestive system, reaching 1,638 nM in the colon content. We suggest that the liver and pancreas affect the content of kynurenic acid in the lumen of the digestive tract.

Paluszkiewicz P; Zgrajka W; Saran T; Schabowski J; Piedra JL; Fedkiv O; Rengman S; Pierzynowski SG; Turski WA

2009-10-01

251

Catalytic wet air oxidation of high concentration pharmaceutical wastewater.  

UK PubMed Central (United Kingdom)

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

Zhan W; Wang X; Li D; Ren Y; Liu D; Kang J

2013-01-01

252

Catalytic wet air oxidation of high concentration pharmaceutical wastewater.  

Science.gov (United States)

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

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

2013-01-01

253

Hydrothermally enhanced electrochemical oxidation of high concentration refractory perfluorooctanoic acid.  

UK PubMed Central (United Kingdom)

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

Xiao H; Lv B; Zhao G; Wang Y; Li M; Li D

2011-12-01

254

Production of pharmaceutical-grade plasmids at high concentration and high supercoiled percentage.  

UK PubMed Central (United Kingdom)

The increased use of plasmid-based vaccines to replace their more challenging viral counterparts has increased the demand for high purity and high concentration plasmids. Here we report the production of plasmids encoding different transgenes for DNA vaccine candidates at gram scale with an integrated process consisting of batch fermentation and limited steps of purification. Plasmid products encoding for eight smallpox antigens that were combined into a bioterrorism DNA vaccine exhibited high purity with undetectable RNA, protein and endotoxin, concentration of up to 13.6mg/mL and supercoiled percentage of 94.5+/-1.1% after storage at -80 degrees C for over 1 year. The process has been scaled up for the cGMP manufacture of pharmaceutical-grade human papillomavirus and influenza DNA vaccines up to a 50g scale, also demonstrating high purity and high concentration.

Cai Y; Rodriguez S; Rameswaran R; Draghia-Akli R; Juba RJ Jr; Hebel H

2010-02-01

255

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

International Nuclear Information System (INIS)

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

2002-01-01

256

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1992-05-01

257

Proposal on limits for chemical exposure in saturation divers' working atmosphere: the case of benzene.  

UK PubMed Central (United Kingdom)

Saturation diving is performed under extreme environmental conditions. The divers are confined to a limited space for several weeks under high environmental pressure and elevated oxygen partial pressure. At present, divers are protected against chemical exposure by standard exposure limits only adjusted for the increased exposure length, i.e. from 8 to 24 hours a day and from 5 to 7 days a week. The objective of the present study was to indicate a procedure for derivation of occupational exposure limits for saturation diving, termed hyperbaric exposure limits (HEL). Using benzene as an example, a procedure is described that includes identification of the latest key documents, extensive literature search with defined exclusion criteria for the literature retrieved. Hematotoxicity and leukemia were defined as the critical effects, and exposure limits based upon concentration and cumulative exposure data and corresponding risks of leukemia were calculated. Possible interactions of high pressure, elevated pO?, and continuous exposure have been assessed, and incorporated in a final suggestion of a HEL for benzene. The procedure should be applicable for other relevant chemicals in the divers' breathing atmosphere. It is emphasized that the lack of interactions from pressure and oxygen indicated for benzene may be completely different for other chemicals.

Djurhuus R; Nossum V; Øvrebø S; Skaug V

2012-03-01

258

Yields of excited states of solutes in irradiated benzene and cyclohexane  

International Nuclear Information System (INIS)

The yields of lowest excited singlet states of diphenyloxazole and p-terphenyl in benzene and of diphenyloxazole, p-terphenyl, and biphenyl in cyclohexane have been measured for excitation by using 85Kr ? particles. The dependence of the yield on solute concentration for benzene solutions is shown to be accurately represented by a Stern-Volmer function from 5 x 10-4 to 10-2 M and to extrapolate at infinite solute concentration to the yield of excited singlet states of neat liquid benzene. The presence of oxygen in the solution does not affect the extrapolation. The absolute efficiencies of energy transfer from irradiated benzene to the solutes are in good agreement with previous measurements made by using optical excitation below the ionization threshold. These results provide additional confirmation that the mechanism of formation of excited solute states in fast-electron-irradiated benzene does not significantly involve electron or hole capture by the solute. They also demonstrate that the inhomogeneity of energy deposition does not affect the ratio of probabilities of the decay of excited benzene by photon emission to its decay by nonradiative energy transfer to the solute. For cyclohexane solutions, it is confirmed that the yields of excited solute states are lower than in benzene solutions at comparable concentration, but larger than would be expected were the same nonionic mechanism to apply as it does in benzene. The consequences of these conclusions are discussed.

1984-01-01

259

Yields of excited states of solutes in irradiated benzene and cyclohexane  

Energy Technology Data Exchange (ETDEWEB)

The yields of lowest excited singlet states of diphenyloxazole and p-terphenyl in benzene and of diphenyloxazole, p-terphenyl, and biphenyl in cyclohexane have been measured for excitation by using /sup 85/Kr ..beta.. particles. The dependence of the yield on solute concentration for benzene solutions is shown to be accurately represented by a Stern-Volmer function from 5 x 10/sup -4/ to 10/sup -2/ M and to extrapolate at infinite solute concentration to the yield of excited singlet states of neat liquid benzene. The presence of oxygen in the solution does not affect the extrapolation. The absolute efficiencies of energy transfer from irradiated benzene to the solutes are in good agreement with previous measurements made by using optical excitation below the ionization threshold. These results provide additional confirmation that the mechanism of formation of excited solute states in fast-electron-irradiated benzene does not significantly involve electron or hole capture by the solute. They also demonstrate that the inhomogeneity of energy deposition does not affect the ratio of probabilities of the decay of excited benzene by photon emission to its decay by nonradiative energy transfer to the solute. For cyclohexane solutions, it is confirmed that the yields of excited solute states are lower than in benzene solutions at comparable concentration, but larger than would be expected were the same nonionic mechanism to apply as it does in benzene. The consequences of these conclusions are discussed.

Choi, H.T.; Hirayama, F.; Lipsky, S.

1984-09-13

260

Viscosity and reptation time in polystyrene-benzene semidilute solutions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We report some preliminary experimental results on Newtonian viscosity ? and reptation time TR in semidilute polystyrene-benzene solutions. We have obtained the following results : ? ? M 3 ? 0.5 c4.5 ? 0.1 and TR ? c2. 8 ? 0.4. The concentration exponent values are not in agreement with de Gennes' t...

Adam, M.; Delsanti, M.

 
 
 
 
261

High urinary phthalate concentration associated with delayed pubarche in girls.  

UK PubMed Central (United Kingdom)

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

Frederiksen H; Sørensen K; Mouritsen A; Aksglaede L; Hagen CP; Petersen JH; Skakkebaek NE; Andersson AM; Juul A

2012-06-01

262

High urinary phthalate concentration associated with delayed pubarche in girls  

DEFF Research Database (Denmark)

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

Frederiksen, H; SØrensen, K

2012-01-01

263

The Solubility of Phenylborate Compounds in Benzene  

Energy Technology Data Exchange (ETDEWEB)

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

Eibling, R.E. [Westinghouse Savannah River Company, AIKEN, SC (United States)

1998-04-01

264

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...of this section: DANGER BENZENE CANCER HAZARD FLAMMABLEâNO SMOKING AUTHORIZED...warning: DANGER CONTAINS BENZENE CANCER HAZARD (3) Information and training...usually available, emerging diagnostic technology and innovative regimes make...

2013-07-01

265

The Solubility of Phenylborate Compounds in Benzene  

International Nuclear Information System (INIS)

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

1998-01-01

266

Problems in the biological monitoring of benzene exposure  

Energy Technology Data Exchange (ETDEWEB)

The biological monitoring of workers exposed to benzene containing mixtures by phenol analysis in urine is complicated by the facts that varying amounts of phenolic compounds are also produced by other precursors than benzene and that coexposure with other chemicals can cause interactions in metabolism and elimination rates. In order to overcome these difficulties it is proposed a) to abandon the colorimetric methods and to use only gas chromatography as a standard and reference method, b) as an overall monitoring concept always to determine phenol pre-exposure values as well as the cresol and creatinine concentrations in urine, and to combine biological monitoring whenever possible with personal air sampling.

Bauer, D.

1984-01-01

267

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

UK PubMed Central (United Kingdom)

Sulfidic benzene-contaminated groundwater was used to fuel a two-chambered microbial fuel cell (MFC) over a period of 770 days. We aimed to understand benzene and sulfide removal processes in the anoxic anode chamber and describe the microbial community enriched over the operational time. Operated in batch feeding-like circular mode, supply of fresh groundwater resulted in a rapid increase in current production, accompanied by decreasing benzene and sulfide concentrations. The total electron recoveries for benzene and sulfide were between 18-49%, implying that benzene and sulfide were not completely oxidized at the anode. Pyrosequencing of 16S rRNA genes from the anode-associated bacterial community revealed the dominance of ?-Proteobacteria (31%), followed by ?-Proteobacteria, Bacteroidetes, ?-Proteobacteria, Chloroflexi, and Firmicutes, most of which are known for anaerobic metabolism. Two-dimensional compound-specific isotope analysis demonstrated that benzene degradation was initiated by monohydroxylation, probably triggered by small amounts of oxygen which had leaked through the cation exchange membrane into the anode chamber. Experiments with labeled [(13) C6 ]-benzene revealed incorporation of (13) C into fatty acids of mainly Gram-negative bacteria, which are therefore candidates for benzene degradation. Our study demonstrated simultaneous benzene and sulfide removal by groundwater microorganisms which use an anode as artificial electron acceptor, thereby releasing an electrical current. Biotechnol. Bioeng. © 2013 Wiley Periodicals, Inc.

Rakoczy J; Feisthauer S; Wasmund K; Bombach P; Neu TR; Vogt C; Richnow HH

2013-06-01

268

Heterogeneous aerobic benzene-degrading communities in oxygen-depleted groundwaters.  

Science.gov (United States)

A sandstone aquifer beneath a petrochemicals plant (SIReN site, UK) is heterogeneously contaminated with benzene and oxygen-depleted. Despite low redox potentials in three of the most contaminated groundwaters (benzene concentrations from 17.8 to 294 mg L(-1)), we observed aerobic benzene degradation in microcosms, indicating the presence in situ of a latent community of obligate aerobic microorganisms or an active community of facultative aerobes responding rapidly to oxygen ingress. Moreover, benzene degradation occurred at the ambient pH of 8.9 and 9.4, considerably more alkaline conditions than previously reported. 16S rRNA analyses showed that the groundwater microcosm communities were distinct from each other, despite sharing the function of aerobic benzene degradation. From DNA fingerprinting, one consortium was dominated by Acidovorax spp., another by Pseudomonas spp.; these benzene-degrading consortia were similar to the in situ communities, perhaps indicating that these organisms are active in situ and degrading benzene microaerophilically or by denitrification. Conversely, in the third sample, benzene degradation occurred only after the community changed from a Rhodoferax-dominated community to a mix of Rhodococcus and Hydrogenophaga spp. Four of the main benzene-degrading strains were brought into culture: Hydrogenophaga and Pseudomonas spp., and two strains of Rhodococcus erythropolis, a ubiquitous and metabolically versatile organism. PMID:17064267

Fahy, Anne; McGenity, Terry J; Timmis, Kenneth N; Ball, Andrew S

2006-11-01

269

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

Science.gov (United States)

Sulfidic benzene-contaminated groundwater was used to fuel a two-chambered microbial fuel cell (MFC) over a period of 770 days. We aimed to understand benzene and sulfide removal processes in the anoxic anode chamber and describe the microbial community enriched over the operational time. Operated in batch feeding-like circular mode, supply of fresh groundwater resulted in a rapid increase in current production, accompanied by decreasing benzene and sulfide concentrations. The total electron recoveries for benzene and sulfide were between 18% and 49%, implying that benzene and sulfide were not completely oxidized at the anode. Pyrosequencing of 16S rRNA genes from the anode-associated bacterial community revealed the dominance of ?-Proteobacteria (31%), followed by ?-Proteobacteria, Bacteroidetes, ?-Proteobacteria, Chloroflexi, and Firmicutes, most of which are known for anaerobic metabolism. Two-dimensional compound-specific isotope analysis demonstrated that benzene degradation was initiated by monohydroxylation, probably triggered by small amounts of oxygen which had leaked through the cation exchange membrane into the anode chamber. Experiments with [(13) C6 ]-benzene revealed incorporation of (13) C into fatty acids of mainly Gram-negative bacteria, which are therefore candidates for benzene degradation. Our study demonstrated simultaneous benzene and sulfide removal by groundwater microorganisms which use an anode as artificial electron acceptor, thereby releasing an electrical current. Biotechnol. Bioeng. 2013;110: 3104-3113. © 2013 Wiley Periodicals, Inc. PMID:23775304

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

2013-07-03

270

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2007-09-15

271

Combustion and soot formation characteristics of benzene-hexane mixtures under controlled ignition lags. Chakka okure seigyoka ni okeru benzene keiter dot n-hexane kongo nenryo no diesel haiki tokusei  

Energy Technology Data Exchange (ETDEWEB)

The influence of the aromatic content of fuel, mainly of benzene and the derivatives on the soot and NO {sub x} emissions from a diesel engine with an auxilliary chamber was analyzed under controlled ignition lags. The soot concentration when used the fuel containing aromatic components was mainly dominated by C/H ratio of the fuels and the ignition lags regardless of molecular structure, could be described by a linear-combination function, and increased with the increase of C/H ratio and the decrease of ignition lag. On the other hand, NO {sub x} concentration increased slightly with the increase of C/H ratio and the ignition lag. The increasing tendency of soot concentration along with the increase of C/H ratio decreased with the decrease of equivalence ratio. When compared with n-hexane, the soot concentration in the combustion chamber based on benzene was remarkably high during the first half of the combustion but the difference between both aromatic components decreased suddenly during the latter half of combustion. The soot forming characteristics of benzene and n-hexane fuel mixture agreed qualitatively between the premixture combustion and the diesel combustion. 11 refs., 12 figs., 2 tabs.

Miyamoto, N.; Ogawa, H. (Hokkaido University, Sapporo (Japan). Faculty of Engineering); Shibuya, M. (Hokkaido University, Sapporo (Japan)); Suzuki, K. (Honda Motor Co. Ltd., Tokyo (Japan)): Chiba, S. (Hokkaido Railway Co., Sapporo (Japan))

1991-05-25

272

Global DNA methylation and low-level exposure to benzene.  

UK PubMed Central (United Kingdom)

INTRODUCTION: Global genomic hypomethylation is a common event in cancer tissues that is frequently observed in hematopoietic malignancies, including leukemia. Benzene, an established leukemogen at high doses, has been suggested to induce hypomethylation based on investigations of DNA methylation in LINE-1 and Alu repetitive elements. Whether global genomic DNA methylation content is reduced in response to benzene exposure is still undetermined. METHODS: We measured global DNA methylation in 78 gasoline station attendants and 58 controls in peripheral blood cells using high-resolution gas chromatography-mass spectrometry. PCR-Pyrosequencing measures of DNA methylation at Alu and LINE-1 repetitive elements, representing a large proportion of methylation in non-coding regions, were also available. Exposure markers included personal airborne benzene, and urinary benzene, t,t-muconic acid (t,t-MA) and S-phelylmercapturic acid. RESULTS: Mean global DNA methylation was 5.474 (+/- 0.083) %5mC in controls and 5.409 (+/- 0.142) %5mC in exposed participants (p = 0.01). All methylation markers were negatively correlated with airborne benzene. Alu and LINE-1 methylation, but not global DNA methylation, were negatively associated with t,t-MA; no association with the other urinary biomarkers was found. Multiple linear regression analysis adjusted for gender and age confirmed the results of correlation analysis and showed a 1.6% decrease in global DNA methylation associated with being gasoline station attendants. Alu and LINE-1 methylation levels were not associated with global DNA methylation. CONCLUSION: Our results show that benzene exposure is associated with alterations in both global DNA and repetitive element methylation. Global and repetitive element methylation levels are not correlated in blood DNA, likely representing independent responses to benzene exposure.

Fustinoni S; Rossella F; Polledri E; Bollati V; Campo L; Byun HM; Agnello L; Consonni D; Pesatori AC; Baccarelli A; Bertazzi PA

2012-03-01

273

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

International Nuclear Information System (INIS)

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

2006-07-25

274

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2006-07-25

275

Inhibition of Drosophila melanogaster acetylcholinesterase by high concentrations of substrate.  

Science.gov (United States)

Acetylcholine hydrolysis by acetylcholinesterase is inhibited at high substrate concentrations. To determine the residues involved in this phenomenon, we have mutated most of the residues lining the active-site gorge but mutating these did not completely eliminate hydrolysis. Thus, we analyzed the effect of a nonhydrolysable substrate analogue on substrate hydrolysis and on reactivation of an analogue of the acetylenzyme. Analyses of various models led us to propose the following sequence of events: the substrate initially binds at the rim of the active-site gorge and then slides down to the bottom of the gorge where it is hydrolyzed. Another substrate molecule can bind to the peripheral site: (a) when the choline is still inside the gorge - it will thereby hinder its exit; (b) after choline has dissociated but before deacetylation occurs - binding at the peripheral site increases deacetylation rate but (c) if a substrate molecule bound to the peripheral site slides down to the bottom of the active-site before the catalytic serine is deacetylated, its new position will prevent the approach of water, thus blocking deacetylation. PMID:15030487

Stojan, Jure; Brochier, Laure; Alies, Carole; Colletier, Jacques Philippe; Fournier, Didier

2004-04-01

276

Estimating airborne benzene exposures from air monitoring data for mineral spirits.  

UK PubMed Central (United Kingdom)

"Low aromatics" vs. "regular" mineral spirits differ substantially in their aromatic hydrocarbon content. Mineral spirits contain benzene and other compounds that boil at temperatures below the cited boiling point range of 300 ° to 415 °F. Available published information shows that until at least 2000, the benzene content of regular mineral spirits was typically 0.1% wt/wt and at times could have been 1.0% wt/wt. The present analysis accounts for benzene's higher volatility compared to mineral spirits as a whole and applies thermodynamic principles to estimate benzene vapor exposure as a subset of measured exposure to total hydrocarbons generated by the evaporation of mineral spirits. For a scenario in which the bulk mineral spirits only partially evaporate, this analysis explains the error in assuming that the mole fraction of benzene to "everything else" is the same in the vapor and liquid phases. It is shown that for a given concentration of total hydrocarbon vapor, the benzene vapor concentration can be more than 65-fold greater during mineral spirits evaporation compared to after all the mineral spirits has evaporated. In turn, it is reasonable to expect that during the use of regular mineral spirits, containing benzene typically at 0.1% wt/wt (as applies to usage prior to 2000), benzene vapor exposures could have exceeded 1 ppm even though the mineral spirits vapor exposure did not exceed 100 ppm, the ACGIH® TLV® time-weighted average (TWA) value for mineral spirits. The same analysis can be applied to current petrochemical products, such as toluene, that contain benzene and for which the required physico-chemical information is available. The analysis provides evidence that the material safety data sheet (MSDS) for a petrochemical product containing benzene at less than 0.1% wt/wt should, pursuant to Hazard Communication Standard requirements, identify the benzene as a hazardous ingredient.

Kopstein M

2011-05-01

277

Estimating airborne benzene exposures from air monitoring data for mineral spirits.  

Science.gov (United States)

"Low aromatics" vs. "regular" mineral spirits differ substantially in their aromatic hydrocarbon content. Mineral spirits contain benzene and other compounds that boil at temperatures below the cited boiling point range of 300 ° to 415 °F. Available published information shows that until at least 2000, the benzene content of regular mineral spirits was typically 0.1% wt/wt and at times could have been 1.0% wt/wt. The present analysis accounts for benzene's higher volatility compared to mineral spirits as a whole and applies thermodynamic principles to estimate benzene vapor exposure as a subset of measured exposure to total hydrocarbons generated by the evaporation of mineral spirits. For a scenario in which the bulk mineral spirits only partially evaporate, this analysis explains the error in assuming that the mole fraction of benzene to "everything else" is the same in the vapor and liquid phases. It is shown that for a given concentration of total hydrocarbon vapor, the benzene vapor concentration can be more than 65-fold greater during mineral spirits evaporation compared to after all the mineral spirits has evaporated. In turn, it is reasonable to expect that during the use of regular mineral spirits, containing benzene typically at 0.1% wt/wt (as applies to usage prior to 2000), benzene vapor exposures could have exceeded 1 ppm even though the mineral spirits vapor exposure did not exceed 100 ppm, the ACGIH® TLV® time-weighted average (TWA) value for mineral spirits. The same analysis can be applied to current petrochemical products, such as toluene, that contain benzene and for which the required physico-chemical information is available. The analysis provides evidence that the material safety data sheet (MSDS) for a petrochemical product containing benzene at less than 0.1% wt/wt should, pursuant to Hazard Communication Standard requirements, identify the benzene as a hazardous ingredient. PMID:21476170

Kopstein, Melvyn

2011-05-01

278

Palladium extraction by triphenylphosphine sulfide in benzene  

International Nuclear Information System (INIS)

The extraction of Pd(II) by triphenylphosphine sulfide (Ph3PS) in benzene from nitric acid solutions has been investigated. The effect of different parameters on the extraction of palladium was studied. Based on the results, an equilibrium model is proposed. The stoichiometry of the extracted species was elucidated and found to be Pd(NO3)22Ph3PS. Possible interference with selected radionuclides that might exist in high level liquid waste was investigated and discussed. (author) 8 refs.; 4 figs.; 1 tab

1992-11-16

279

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

Science.gov (United States)

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

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

2012-03-29

280

Assessment of human exposure to benzene through foods from the Belgian market.  

Science.gov (United States)

Benzene is a volatile organic compound known to be carcinogenic to humans (Group 1) and may be present in food. In the present study, 455 food samples from the Belgian market were analyzed for benzene contents and some possible sources of its occurrence in the foodstuffs were evaluated. Benzene was found above the level of detection in 58% of analyzed samples with the highest contents found in processed foods such as smoked and canned fish, and foods which contained these as ingredients (up to 76.21 ?g kg(-1)). Unprocessed foods such as raw meat, fish, and eggs contained much lower concentrations of benzene. Using the benzene concentrations in food, a quantitative dietary exposure assessment of benzene intake was conducted on a national representative sample of the Belgian population over 15 years of age. The mean benzene intake for all foods was 0.020 ?g kg bw d(-1) according to a probabilistic analysis. These values are below the minimum risk level for oral chronic exposure to benzene (0.5 ?g kg bw d(-1)). PMID:22483726

Medeiros Vinci, Raquel; Jacxsens, Liesbeth; Van Loco, Joris; Matsiko, Eric; Lachat, Carl; de Schaetzen, Thibault; Canfyn, Michael; Van Overmeire, Ilse; Kolsteren, Patrick; De Meulenaer, Bruno

2012-04-05

 
 
 
 
281

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-10-15

282

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

UK PubMed Central (United Kingdom)

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

Atamna IZ; Muschik GM; Issaq HJ

1990-01-01

283

Defining high-sensitivity cardiac troponin concentrations in the community.  

UK PubMed Central (United Kingdom)

BACKGROUND: High-sensitivity cardiac troponin (hs-cTn) assays are now available that can detect measurable troponin in significantly more individuals in the general population than conventional assays. The clinical use of these hs-cTn assays depends on the development of proper reference values. Therefore, our objective was to define hs-cTnI reference values and determinants in the general community, in a healthy reference cohort, and in subsets with diseases. MATERIALS AND METHODS: A well-characterized community-based cohort of 2042 study participants underwent clinical assessment and echocardiographic evaluation. Baseline hs-cTnI measurements were obtained in 1843 individuals. A healthy reference cohort (n = 565) without cardiac, renal, or echocardiographic abnormalities was identified. RESULTS: Measurable hs-cTnI was identified in 1716 (93%) of the community-based study cohort and 499 (88%) of the healthy reference cohort. Parameters that significantly contributed to higher hs-cTnI concentrations in the healthy reference cohort included age, male sex, systolic blood pressure, and left ventricular mass. Glomerular filtration rate and body mass index were not independently associated with hs-cTnI in the healthy reference cohort. Individuals with diastolic and systolic dysfunction, hypertension, and coronary artery disease (but not impaired renal function) had significantly higher hs-cTnI values than the healthy reference cohort. CONCLUSIONS: We assessed an hs-cTnI assay with the aid of echocardiographic imaging in a large, well-characterized community-based cohort. hs-cTnI is remarkably sensitive in the general population, and there are important sex and age differences among healthy reference individuals. These results have important implications for defining hs-cTnI reference values and identifying disease.

McKie PM; Heublein DM; Scott CG; Gantzer ML; Mehta RA; Rodeheffer RJ; Redfield MM; Burnett JC Jr; Jaffe AS

2013-07-01

284

Method for producing benzene aromatic hydrocarbon from crude benzole  

UK PubMed Central (United Kingdom)

The present invention relates to process of producing benzene series arene with crude benzole. Whole fraction crude benzole and other hydrocarbon oil are mixed, and the mixed oil is produced into high purity benzene, toluene and xylene through the process including hydrorefining, reforming, solvent extracting, distilling, rectifying and other steps. The present invention has the features of no arene loss, total arene yield over 100 %, high purity of arene products over 99.9 %, low S and N impurity content in arene products less than 1 ppm and long operation period of the processing apparatus. The present invention is especially suitable for use in refinery possessing hydrogenation equipment and reforming equipment.

SHE XICHUN ZHU

285

Structure of DNA in a nucleosome core at high salt concentration and at high temperature.  

Science.gov (United States)

We have used hydroxyl radical cleavage of DNA to probe the organization of the nucleosome core at high salt concentration and high temperature. The rotational and translational positioning of a DNA fragment, containing part of the Xenopus borealis 5S RNA gene, on the histone octamer is maintained between salt concentrations of 0.0 and 0.8 M NaCl and between temperatures of 0 and 75 degrees C. These results provide evidence that the energy of bending DNA around the nucleosome is independent of salt concentration and temperature in this range. They illustrate the severe energetic requirements necessary to displace DNA from previously organized contacts with histones in the nucleosome core. PMID:8383529

Bashkin, J; Hayes, J J; Tullius, T D; Wolffe, A P

1993-03-01

286

Structure of DNA in a nucleosome core at high salt concentration and at high temperature.  

UK PubMed Central (United Kingdom)

We have used hydroxyl radical cleavage of DNA to probe the organization of the nucleosome core at high salt concentration and high temperature. The rotational and translational positioning of a DNA fragment, containing part of the Xenopus borealis 5S RNA gene, on the histone octamer is maintained between salt concentrations of 0.0 and 0.8 M NaCl and between temperatures of 0 and 75 degrees C. These results provide evidence that the energy of bending DNA around the nucleosome is independent of salt concentration and temperature in this range. They illustrate the severe energetic requirements necessary to displace DNA from previously organized contacts with histones in the nucleosome core.

Bashkin J; Hayes JJ; Tullius TD; Wolffe AP

1993-03-01

287

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

Directory of Open Access Journals (Sweden)

Full Text Available In a clinical study, the efficacy of gamma benzene hexachloride lotion was evaluated in 50 adult patients in scabies using 2% concentration and in 24 children under 8 years of age using 1% concentration. Use of other scabicidal preparation was 25% benzyl benzoate emulsion for a comparison with second group of patients of the same size. Two applications for 1 day of 2% gamma benzene hexachloride lotion proved to be far more effective a scabicidal drug (68% cure) in adult and 1% gamma benzene hexachloride (91.7% cure) in children compared to benzyl benzoate emulsion.

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

1995-01-01

288

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

Scientific Electronic Library Online (English)

Full Text Available Abstract in english In step with the need to develop statistical procedures to manage small-size environmental samples, in this work we have used concentration values of benzene (C6H6), concurrently detected by seven outdoor and indoor monitoring stations over 12 000 minutes, in order to assess the representativeness of collected data and the impact of the pollutant on indoor environment. Clearly, the former issue is strictly connected to sampling-site geometry, which proves critical to corr (more) ectly 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.

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

2010-12-01

289

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

UK PubMed Central (United Kingdom)

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

Cervantes FJ; Mancilla AR; Ríos-del Toro EE; Alpuche-Solís AG; Montoya-Lorenzana L

2011-11-01

290

Local structure and dynamics of benzene confined in the IRMOF-1 nanocavity as studied by molecular dynamics simulation.  

UK PubMed Central (United Kingdom)

The local structure and dynamic behaviour of a benzene molecular assembly confined within the nano-cavities of a zinc-based metal-organic framework, [Zn(4)O(CO(2)C(6)H(4)CO(2))(3)](n) (IRMOF-1), were investigated by means of molecular dynamics (MD) simulations. The local structure of the confined benzene molecules was evaluated using radial distribution functions. The sites for adsorption of benzene in IRMOF-1 were well defined by the simulation. The diffusion coefficients at ambient temperature suggested that the mobility of the confined benzene was high, comparable to the bulk fluid. Decreasing the temperature gave rise to the aggregation of benzene in the IRMOF-1 frameworks. Molecular aggregation was attributed to the localization of benzene in the large and the small cavities of IRMOF-1, respectively. Both the translational diffusion coefficient and the trajectory of benzene provided evidence that the localization of benzene in the large and the small cavities takes place at ca. 200 K. Furthermore, at high benzene loading, the migration of benzene in the small cavities was prevented (frozen) below 135 K. Thus, the translational degree of freedom of the benzene molecules changed drastically, depending on the temperature.

Takakura K; Ueda T; Miyakubo K; Eguchi T

2013-01-01

291

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1996-10-01

292

Methods and devices for high-throughput dielectrophoretic concentration  

Energy Technology Data Exchange (ETDEWEB)

Disclosed herein are methods and devices for assaying and concentrating analytes in a fluid sample using dielectrophoresis. As disclosed, the methods and devices utilize substrates having a plurality of pores through which analytes can be selectively prevented from passing, or inhibited, on application of an appropriate electric field waveform. The pores of the substrate produce nonuniform electric field having local extrema located near the pores. These nonuniform fields drive dielectrophoresis, which produces the inhibition. Arrangements of electrodes and porous substrates support continuous, bulk, multi-dimensional, and staged selective concentration.

Simmons, Blake A. (San Francisco, CA); Cummings, Eric B. (Livermore, CA); Fiechtner, Gregory J. (Germantown, MD); Fintschenko, Yolanda (Livermore, CA); McGraw, Gregory J. (Ann Arbor, MI); Salmi, Allen (Escalon, CA)

2010-02-23

293

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

Science.gov (United States)

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

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

2006-09-20

294

Bonding of benzene with excited States of Fe7.  

Science.gov (United States)

The interaction between high-spin Fe7 clusters and a benzene molecule was studied using the BPW91/6-311++G(2d,2p) method. The Fe7-C6H6 ground state has a T-shaped structure, similar to that of the benzene dimer, and a multiplicity M = 2S + 1 = 19 (S = total spin). The carbon atoms are bonded to a single equatorial iron atom, which experiences a dramatic decrease in its magnetic moment, from 3.1 to -0.8 mu(B); the magnetic moments of other Fe atoms are larger than those in the ground-state Fe7 cluster. Such unexpected magnetic behavior of the cluster is crucial for adsorption of benzene. PMID:18484712

Valencia, Israel; Chávez, Victor; Castro, Miguel

2008-05-17

295

Bonding of benzene with excited States of Fe7.  

UK PubMed Central (United Kingdom)

The interaction between high-spin Fe7 clusters and a benzene molecule was studied using the BPW91/6-311++G(2d,2p) method. The Fe7-C6H6 ground state has a T-shaped structure, similar to that of the benzene dimer, and a multiplicity M = 2S + 1 = 19 (S = total spin). The carbon atoms are bonded to a single equatorial iron atom, which experiences a dramatic decrease in its magnetic moment, from 3.1 to -0.8 mu(B); the magnetic moments of other Fe atoms are larger than those in the ground-state Fe7 cluster. Such unexpected magnetic behavior of the cluster is crucial for adsorption of benzene.

Valencia I; Chávez V; Castro M

2008-06-01

296

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-04-15

297

Inhibition of human topoisomerase II in vitro by bioactive benzene metabolites  

Energy Technology Data Exchange (ETDEWEB)

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

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

1996-12-01

298

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

Science.gov (United States)

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

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

2012-10-22

299

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

UK PubMed Central (United Kingdom)

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.

Hollins DM; Kerger BD; Unice KM; Knutsen JS; Madl AK; Sahmel JE; Paustenbach DJ

2013-06-01

300

Thiamine status of feedlot cattle fed a high-concentrate diet  

Digital Repository Infrastructure Vision for European Research (DRIVER)

As thiamine status of ruminants is adversely affected by rumen acidity, this study investigated whether or not thiamine deficiency occurs in feedlot cattle fed a high concentrate diet. Fifty 1- to 2-year-old feedlot cattle fed a high concentrate diet (75% barley) for at least 3 mo (high concentrate ...

Karapinar, Tolga; Dabak, Murat; Kizil, Omer

 
 
 
 
301

Dimerization in Highly Concentrated Solutions of Phosphoimidazolide Activated Monomucleotides  

Science.gov (United States)

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

Kanavarioti, Anastassia

1997-08-01

302

A Mild, Thermal Pentafulvene-to-Benzene Rearrangement.  

UK PubMed Central (United Kingdom)

Walk this way: More than 40?years after the discovery that fulvene can thermally rearrange to benzene at high temperatures, it has been found that 6,6-dicyanopentafulvenes can rearrange quantitatively to 1,3- and 1,4-dicyanobenzenes under mild conditions in polar aprotic solvents. A polar "ring-walk" mechanism is proposed to explain this unprecedented reactivity.

Finke AD; Haberland S; Schweizer WB; Chen P; Diederich F

2013-09-01

303

Toxicological profile for benzene. Final report  

Energy Technology Data Exchange (ETDEWEB)

The Statement was prepared to give information about benzene and to emphasize the human health effects that may result from exposure to it. The Environmental Protection Agency (EPA) has identified 1,300 hazardous waste sites as the most serious in the nation. Benzene has been found in at least 743 of these sites. However, one does not know how many of the 1,300 NPL sites have been evaluated for benzene. As EPA evaluates more sites, the number of sites at which benzene is found may change. The information is important to know because benzene may cause harmful health effects and because these sites are potential or actual sources of human exposure to benzene.

Jewell, C.S.E.; Hibbs, B.F.; Brankovan, V.; Anderson, E.

1993-04-01

304

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2004-07-01

305

Unexpectedly high indoor hydroxyl radical concentrations associated with nitrous acid  

Science.gov (United States)

The hydroxyl (OH) radical is the most important oxidant in the atmosphere since it controls its self-oxidizing capacity. The main sources of OH radicals are the photolysis of ozone and the photolysis of nitrous acid (HONO). Due to the attenuation of solar radiation in the indoor environment, the possibility of OH formation through photolytic pathways indoors has been ignored up to now. In the indoor air, the ozonolysis of alkenes has been suggested as an alternative route of OH formation. Models and indirect measurements performed up to now according to this hypothesis suggest concentrations of OH radicals on the order of 104–105 molecules per cubic centimeter. Here, we present direct measurements of significant amounts of OH radicals of up to 1.8?106 molecules per cubic centimeter during an experimental campaign carried out in a school classroom in Marseille. This concentration is on the same order of magnitude of outdoor OH levels in the urban scenario. We also show that photolysis of HONO is an important source of OH radicals indoors under certain conditions (i.e., direct solar irradiation inside the room). Additionally, the OH concentrations were found to follow a linear dependence with the product J(HONO)?[HONO]. This was also supported by using a simple quasiphotostationary state model on the OH radical budget. These findings force a change in our understanding of indoor air quality because the reactivity linked to OH would involve formation of secondary species through chemical reactions that are potentially more hazardous than the primary pollutants in the indoor air.

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

2013-01-01

306

Unexpectedly high indoor hydroxyl radical concentrations associated with nitrous acid.  

UK PubMed Central (United Kingdom)

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

Gómez Alvarez E; Amedro D; Afif C; Gligorovski S; Schoemacker C; Fittschen C; Doussin JF; Wortham H

2013-08-01

307

Ion exchange method of obtaining high grade europium concentrates  

Energy Technology Data Exchange (ETDEWEB)

The studies of receiving the europium from Gd-Sm-Eu concentrate and the separation of Eu-Gd pair by ion-exchange method on Wofatit KPS x 8 using as eluents ..cap alpha..-HIBA, ammonia lactate and mixed eluent EDTA-ammonia acetate, were carried out. The best results were obtained by the use of ..cap alpha..-HIBA as an eluent (0.1-0.15 M and pH 3.9-4.25). As a result of Eu-Gd pair separation by using ..cap alpha..-HIBA as an eluent, Eu/sub 2/O/sub 3/ of purity >=3 N was received.

Hubicka, H.; Hubicki, Z.; Jusiak, S.; Brzyska, W. (Uniwersytet Marii Curie-Sklodowskiej, Lublin (Poland))

1980-01-01

308

Catalytically-mediated denitration of highly HNO3 concentrated solutions  

International Nuclear Information System (INIS)

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

2000-01-01

309

Highly efficient photovoltaic generation method using fluorescent solar concentrator  

Energy Technology Data Exchange (ETDEWEB)

The solar cell has wide variety with various production cost, photo-conversion efficiency and shape/appearance as well as spectral sensitivity (band gap). A tandem type solar cell, which duplicates multi-layer of amorphous solar cell with different band gap, converts the solar light into electric energy according to its original wavelength wherein the selection range of the cells installed multifold is limited. In this invention, however, by the use of a fluorescent solar concentrator, wavelengths are screened and the solar energy, especially the solar light, is efficiently converted into electric energy by means of the solar cell respectively suited for the individual wavelength ranges. (4 figs)

Horigome, Takashi; Shimizu, Takuo

1988-01-12

310

Thermal study of metalloporphyrin complexes with benzene  

International Nuclear Information System (INIS)

Crystallosolvates of MP (P - dianions of tetra(3,5-di-tret-butylphenyl)porphyrin, M - Co, Ni, Cu, Zn, Cd, Hg) complexes with benzene are obtained by isothermal evaporation of the solutions at 35 Deg C. The processes of their thermal decomposition are investigated. Composition, temperature and enthalpy of benzene evaporation from the crystallosolvates are determined. It is detected that ?-system of of macrocycle of metalloporphyrinates appears as ?-donor to aromatic system of benzene molecule

2005-01-01

311

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

Science.gov (United States)

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

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

2008-08-01

312

Leukemia risk in caprolactam workers exposed to benzene.  

UK PubMed Central (United Kingdom)

PURPOSE: To investigate the leukemia risk in a group of benzene exposed workers. METHODS: We conducted a retrospective cohort mortality study on 311 men who worked between January 1, 1951 and December 31, 1968 in a Caprolactam plant in the Netherlands. In the production of Caprolactam (the Nylon 6 monomer) pure benzene is used as an extracting agent and the workers at this plant have been exposed to substantial concentrations of benzene. The cohort was followed for mortality until January 1, 2001. The total mortality was below the expected number, which was mainly caused by a deficit of cardiovascular disease mortality. RESULTS: In the total group, there was one death from leukemia, compared with an expected number of 1.17. Despite the substantial exposures to benzene (on average 159 ppm-years per person) there was no indication for increased leukemia mortality within the cohort. We have applied earlier quantitative risk assessments to our cohort and conclude that some of these assessments overestimate the risk observed in our cohort of Caprolactam workers.

Swaen GM; Scheffers T; de Cock J; Slangen J; Drooge H

2005-01-01

313

Fluorescence-detected sedimentation in dilute and highly concentrated solutions.  

UK PubMed Central (United Kingdom)

Analytical ultracentrifugation (AUC) is a powerful, first-principles method for characterizing macromolecules in solution. The recent development of fluorescence-detected sedimentation for the AUC (AU-FDS) has extended the sensitivity and selectivity of the instrument which, in turn, has enabled the study of both higher affinity interactions and the sedimentation of one component in complex, concentrated solutions. While still in its infancy, AU-FDS is becoming more widespread as shown by the increasing number of literature reports citing its use. While AU-FDS enables the analysis of systems not amenable to absorbance or interferometric detection, its use is not without limitations. In most cases, preparing samples for AU-FDS analyses requires chemical conjugation with fluorescent dyes, a step that may influence the size or shape of a molecule sufficiently to alter its transport during sedimentation. Careful preparation and characterization of the amount of free dye and the degree and site specificity of labeling is required for robust interpretation of AU-FDS data. In some cases, studies of the effect of labeling on the structure, activity, or association properties of the macromolecule may be warranted. However, these complications are of minor consequence compared to the unique information that can be obtained by AU-FDS. In particular, its ability to provide direct, physical characterization of the thermodynamic behavior of molecules in complex and concentrated solutions makes AU-FDS a powerful technology for understanding the physical underpinnings of living systems.

Kingsbury JS; Laue TM

2011-01-01

314

Development of high-efficiency concentrator cell configuration. Final report  

Energy Technology Data Exchange (ETDEWEB)

Development of a reflective spectrum-splitting system is described. This system uses a high-bandgap cell with a reflective back contact to reflect below-bandgap light to a second cell with a lower bandgap. The report discusses system and cell design. It then describes a process for making a think, glass-bonded high-bandgap cell with a back surface reflector, appropriate for this application.

Borden, P.G.

1984-02-01

315

Production of Phenol from Benzene via Cumene  

Science.gov (United States)

|Describes an undergraduate chemistry laboratory experiment involving the production of phenol from benzene with the intermediate production of isopropylbenzene and isopropylbenzene hydroperoxide. (SL)|

Daniels, D. J.; And Others

1976-01-01

316

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

Science.gov (United States)

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

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

2009-01-01

317

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

UK PubMed Central (United Kingdom)

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

Zhao C; Zhang J; Luan Z; Peng X; Ren X

2009-01-01

318

Adverse Effect of High Glucose Concentration on Stem Cell Therapy  

Directory of Open Access Journals (Sweden)

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

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

2013-01-01

319

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

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Epidemiologic studies suggest that long term low dose celecoxib use significantly lowers breast cancer risk. We previously demonstrated that 400 mg celecoxib taken twice daily for 2 weeks lowered circulating plasma and breast nipple aspirate fluid (NAF) prostaglandin (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 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.

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

2008-01-01

320

Detection of DNA damage in human lymphocytes by alkaline single cell gel electrophoresis after exposure to benzene or benzene metabolites.  

UK PubMed Central (United Kingdom)

The alkaline single cell gel electrophoresis (Comet) assay was applied to study the occurrence of DNA damage in peripheral lymphocytes of human subjects with occupational exposure to low levels of benzene (twelve gasoline station attendants, with average benzene exposure of 0.3 mg/m3, 8 h TWA). The results obtained show a significant excess of DNA damage in lymphocytes of exposed workers, compared to matched unexposed controls (p = 0.028, Mann-Whitney U-test). Averaged tail moment values, based on 100 cells/individual, were 1.900 microns in the exposed and 0.936 micron in the unexposed group. In addition, exposed subjects showed a clearcut excess of heavily damaged cells, with tail moments > 90th percentile of the overall distribution (13.5 vs. 6.5%, p = 0.013, Mann-Whitney U-test). No correlation was found between the extent of DNA damage and the ages or smoking habits of the subjects. In order to assess the plausibility of the involvement of benzene in the results of the ex vivo study, further experiments were performed treating in vitro peripheral lymphocytes from unexposed donors with benzene metabolites hydroquinone, benzoquinone and benzenetriol. In these experiments, all benzene metabolites exerted a marked effect on resting lymphocytes, the lowest effective concentrations being below 1 microgram/ml. Conversely, far greater concentrations were required for the induction of significant DNA damage in parallel experiments with hydroquinone on mitogen stimulated lymphocytes. Addition of the DNA repair inhibitor cytosine arabinoside (Ara-C, 1-10 micrograms/ml) partially restored the sensitivity of stimulated cells to hydroquinone, an indication of the active processing of induced DNA lesions in growing cells. These results are discussed also in relation to the role of peripheral lymphocytes as target tissue in the biomonitoring of human exposure to genotoxic agents.

Andreoli C; Leopardi P; Crebelli R

1997-06-01

 
 
 
 
321

Detection of DNA damage in human lymphocytes by alkaline single cell gel electrophoresis after exposure to benzene or benzene metabolites.  

Science.gov (United States)

The alkaline single cell gel electrophoresis (Comet) assay was applied to study the occurrence of DNA damage in peripheral lymphocytes of human subjects with occupational exposure to low levels of benzene (twelve gasoline station attendants, with average benzene exposure of 0.3 mg/m3, 8 h TWA). The results obtained show a significant excess of DNA damage in lymphocytes of exposed workers, compared to matched unexposed controls (p = 0.028, Mann-Whitney U-test). Averaged tail moment values, based on 100 cells/individual, were 1.900 microns in the exposed and 0.936 micron in the unexposed group. In addition, exposed subjects showed a clearcut excess of heavily damaged cells, with tail moments > 90th percentile of the overall distribution (13.5 vs. 6.5%, p = 0.013, Mann-Whitney U-test). No correlation was found between the extent of DNA damage and the ages or smoking habits of the subjects. In order to assess the plausibility of the involvement of benzene in the results of the ex vivo study, further experiments were performed treating in vitro peripheral lymphocytes from unexposed donors with benzene metabolites hydroquinone, benzoquinone and benzenetriol. In these experiments, all benzene metabolites exerted a marked effect on resting lymphocytes, the lowest effective concentrations being below 1 microgram/ml. Conversely, far greater concentrations were required for the induction of significant DNA damage in parallel experiments with hydroquinone on mitogen stimulated lymphocytes. Addition of the DNA repair inhibitor cytosine arabinoside (Ara-C, 1-10 micrograms/ml) partially restored the sensitivity of stimulated cells to hydroquinone, an indication of the active processing of induced DNA lesions in growing cells. These results are discussed also in relation to the role of peripheral lymphocytes as target tissue in the biomonitoring of human exposure to genotoxic agents. PMID:9219584

Andreoli, C; Leopardi, P; Crebelli, R

1997-06-01

322

N-acetyl-beta-D-glucosaminidase in lymphocytes of workers exposed to benzene and its homologues  

Energy Technology Data Exchange (ETDEWEB)

In 108 workers having occupational contact with benzene and its homologues by 1 to 122 months, the activity of N-acetyl-beta-D-glucosaminidase (NAG) within the peripheral blood lymphocytes was estimated by means of cytochemical method. The benzene, the toluene and the xylene concentration at work stands was equal to 0-370, 0-580 and 0-560 mg/cu . m, respectively. In 41 workers having the service time equal to 55-122 months the NAG deficiency within the lymphocyte lysosomes was stated. Above phenomenon is probably due to disintegration of lysosomes caused by lipophilic properties of benzene.

Moszczynski, P.; Lisiewicz, J.

1984-01-01

323

Environmental and occupational exposure to benzene in Thailand.  

UK PubMed Central (United Kingdom)

Exposure to benzene in air is a concern in Thailand, particularly since it was observed that the incidence of blood-related cancers, such as leukemia and lymphoma, has increased in the past few decades. In Bangkok, the mean atmospheric levels of benzene on main roads and in schools were 33.71 and 8.25 ppb, respectively, while in gasoline service stations and petrochemical factories the mean ambient levels were 64.78 and 66.24 ppb, respectively. Cloth vendors (22.61 ppb) and grilled-meat vendors (28.19 ppb) working on the roadsides were exposed to significantly higher levels of benzene than the control group (12.95 ppb; p<0.05). Bangkok school children (5.50 ppb) were exposed to significantly higher levels of benzene than provincial school children (2.54 ppb; p<0.01). Factory workers (73.55 ppb) and gasoline service attendants (121.67 ppb) were exposed to significantly higher levels of benzene than control workers (4.77 ppb; p<0.001). In accordance with the increased benzene exposures, levels of urinary trans,trans-muconic acid (MA) were significantly increased in all benzene-exposed groups. In school children, the levels of MA were relatively high, taking into account the much lower level of exposure. Blood benzene levels were also significantly increased in Bangkok school children (77.97 ppt; p<0.01), gasoline service attendants (641.84 ppt; p<0.05) and factory workers (572.61 ppt; p<0.001), when compared with the respective controls. DNA damage, determined as DNA strand breaks, was found to be elevated in gasoline service attendants, petrochemical factory workers, and Bangkok school children (p<0.001). The cytogenetic challenge assay, which measures DNA repair capacity, showed varying levels of significant increases in the numbers of dicentrics and deletions in gasoline service attendants, petrochemical factory workers and Bangkok school children, indicating a decrease in DNA repair capacity in these subjects.

Navasumrit P; Chanvaivit S; Intarasunanont P; Arayasiri M; Lauhareungpanya N; Parnlob V; Settachan D; Ruchirawat M

2005-05-01

324

Electrophilic mercuration and thallation of benzene and substituted benzenes in trifluoroacetic acid solution*  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The mercuration and thallation of benzene and substituted benzenes was studied with mercuric and thallic trifluoroacetate, respectively, in trifluoroacetic acid. With the shortest reaction time (1 sec) at 0°, the relative rate of mercuration of toluene compared to that of benzene was 17.5, with the ...

Olah, George A.; Hashimoto, Iwao; Lin, Henry C.

325

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...

326

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

UK PubMed Central (United Kingdom)

Statistical evaluation of two large statewide data sets from the California State Water Board's Groundwater Ambient Monitoring and Assessment Program (1973 wells) and the California Department of Public Health (12,417 wells) reveals that benzene occurs infrequently (1.7%) and at generally low concentrations (median detected concentration of 0.024 ?g/L) in groundwater used for public supply in California. When detected, benzene is more often related to geogenic (45% of detections) than anthropogenic sources (27% of detections). Similar relations are evident for the sum of 17 hydrocarbons analyzed. Benzene occurs most frequently and at the highest concentrations in old, brackish, and reducing groundwater; the detection frequency was 13.0% in groundwater with tritium <1 pCi/L, specific conductance >1600 ?S/cm, and anoxic conditions. This groundwater is typically deep (>180 m). Benzene occurs somewhat less frequently in recent, shallow, and reducing groundwater; the detection frequency was 2.6% in groundwater with tritium ?1 pCi/L, depth <30 m, and anoxic conditions. Evidence for geogenic sources of benzene include: higher concentrations and detection frequencies with increasing well depth, groundwater age, and proximity to oil and gas fields; and higher salinity and lower chloride/iodide ratios in old groundwater with detections of benzene, consistent with interactions with oil-field brines.

Landon MK; Belitz K

2012-08-01

327

High plasma uric acid concentration: causes and consequences  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract High plasma uric acid (UA) is a precipitating factor for gout and renal calculi as well as a strong risk factor for Metabolic Syndrome and cardiovascular disease. The main causes for higher plasma UA are either lower excretion, higher synthesis or both. Higher waist circumference ...

de Oliveira Erick; Burini Roberto

328

Structural Studies of Pyrrole-Benzene Complexes by Chirped-Pulse Rotational Spectroscopy  

Science.gov (United States)

Non-covalent intermolecular interactions are important in structural biology. The N-H \\cdots ? hydrogen bond between amino acid side chains is an important structural determinant and highly affects the secondary structure of proteins. The pyrrole-benzene complex can be viewed as a model system for studying these fundamental interactions. Previous IR and UV spectroscopic studies of the pyrrole-benzene complex by Dauster et al. support a T-shaped structure with an N-H \\cdots ? hydrogen bond to the benzene ring. In order to obtain accurate structural information we have investigated the broadband rotational spectrum of the supersonic-jet cooled complexes of pyrrole with benzene and benzene-d_{1} in the 2-18 GHz frequency range. In addition to the hetero dimer we have also observed the two cyclic mixed trimers (pyrrole)_{2}-benzene and pyrrole-(benzene)_{2}. I. Dauster, C. A. Rice, P. Zielke, and M. A. Suhm Phys. Chem. Chem. Phys. {10}, 2827 (2008) C. Pfaffen, D. Infanger, P. Ottiger, H. M. Frey, and S. Leutwyler Phys. Chem. Chem. Phys. {13}, 14110 (2011)

Lobsiger, Simon; Perez, Cristobal; Zaleski, Daniel P.; Seifert, Nathan A.; Pate, Brooks H.; Pfaffen, Chantal; Trachsel, Maria A.; Leutwyler, Samuel

2013-06-01

329

Major sources of benzene exposure  

Energy Technology Data Exchange (ETDEWEB)

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 activities, such as driving and using attached garages. (Emissions from consumer products, building materials, paints, and adhesives may also be important, although data are largely lacking.) The traditional sources of atmospheric emissions (auto exhaust and industrial emissions) account for only about 20% of total exposure. Environmental tobacco smoke is an important source, accounting for about 5% of total nationwide exposure. A number of sources sometimes considered important, such as petroleum refining operations, petrochemical manufacturing, oil storage tanks, urban-industrial areas, service stations, certain foods, groundwater contamination, and underground gasoline leaks, appear to be unimportant on a nationwide basis.

Wallace, L.A. (Environmental Protection Agency, Washington, DC (USA))

1989-07-01

330

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2002-07-01

331

Correlation between iron mobilization and emergence of benzene in leachate at old landfills.  

UK PubMed Central (United Kingdom)

Leachate monitoring data from a closed municipal solid waste (MSW) landfill with negligible gas production showed increasing iron, alkalinity and benzene levels over time. Due to significant rain water infiltration, concentration data alone was not adequate to analyze the possible correlations between the leachate quality parameters monitored. When quantities (kg/d) present in leachate rather than concentrations (mg/L) of benzene, bicarbonate and iron were analyzed; there were significant correlations between benzene and iron as well as biocarbonate and iron quantities. Increasing iron quantity in leachate was accompanied by increasing quantities of benzene and bicarbonate which are indicative of transformation reactions of polymeric organic compounds present in MSW. The results indicate that biotransformation mechanisms in landfills are similar to those in anaerobic sediments due to lack of electron acceptors with higher energy yields.

Tansel B

2013-05-01

332

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1998-12-31

333

Characterization of highly concentrated coal water mixture (CWM)  

Energy Technology Data Exchange (ETDEWEB)

The sediment volume was measured to evaluate characteristics of CWM. 6 kinds of coal samples were prepared to CWM through grinding, sizing and mixing so that particle size equal to and less than 200 mesh became about 80% and further four different sizes of powdered coal were prepared to make CWMs of 40% solid concentration from Datung coal. Several sediment volumes were measured not only in the gravitational field, but also in the centrifugal field. Without a additive, finer the particle size, more the gravitational sediment volume. In case of the centrifugal method, the compactness and the sediment volume were influenced by the fine particle quantity and the applied centrifugal force. Influence of a additive depended on surface properties of coal particles. Comparing the gravitational sediment volume with the centrifugal one, the coal wetness, the effect and dispersibility of the additive, and the compactness could be estimated to judge and improve the CWM stability. Larger the apparent viscosity, more the sediment volume. It became possible to chracterize CWM by measuring the sediment volume. (11 figs, 2 tabs, 8 refs)

Suzuki, Shigeyuki; Yamagata, Yoshio; Tanaka, Tadatsugu

1987-09-10

334

High-efficiency Köhler photovoltaic concentrators with external light confinement  

Science.gov (United States)

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

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

2011-09-01

335

High plasma uric acid concentration: causes and consequences  

Directory of Open Access Journals (Sweden)

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

de Oliveira Erick; Burini Roberto

2012-01-01

336

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

Energy Technology Data Exchange (ETDEWEB)

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

Ghigo, G.; Tonachini, G.

1999-09-15

337

PREPARATION METHOD FOR THE HIGHLY CONCENTRATED EXTRACT FROM MACA AND THE COMPOSITION CONTAINING THE SAME  

UK PubMed Central (United Kingdom)

PURPOSE: A producing method of a highly concentrated maca extract and a composition thereof are provided to use food ingredients as a solvent. CONSTITUTION: A producing method of a highly concentrated maca extract comprises the following steps: adding fermentation alcohol with the ethanol concentration of 90~95.5%(v/v) into maca powder for extracting concentrating the obtained extract to make the concentration of solid portion into 35~45%(w/v) adding water into the extract to make the concentration of the solid portion into 10%(w/v) and settling the extract for more than 24hours at 5~10deg C to obtain an oil layer.

PARK SANG JAE; KANG BYUONG SIK; WANG YUN KYUNG; KWON SUNG PIL

338

HIGH CONCENTRATION TOPICAL INSECTICIDE CONTAINING INSECT GROWTH REGULATOR.  

UK PubMed Central (United Kingdom)

A topical insecticide is provided which can be safe to use and avoids many common deleterious side effects of conventional topical insecticides. The insecticide contains an insecticide and an insect growth regulator effective for killing fleas, flea larvae and flea eggs. The insecticide is formulated by dissolving an insecticidal (tetrahydro-3-furanyl) methylamine derivative and an insect growth regulator (IGR) in a solvent containing N-octyl pyrrolidone and/or N-methyl pyrrolidone to increase the solvency of the IGR component, thereby providing an insecticide having high insecticidal activity.

AHN ALBERT; COTTRELL IAN W; DORNEVAL LINDA

339

High concentration topical insecticide containing insect growth regulator  

UK PubMed Central (United Kingdom)

A topical insecticide is provided which can be safe to use and avoids many common deleterious side effects of conventional topical insecticides. The insecticide contains an insecticide and an insect growth regulator effective for killing fleas, flea larvae and flea eggs. The insecticide is formulated by dissolving an insecticidal (tetrahydro-3-furanyl) methylamine derivative and an insect growth regulator (IGR) in a solvent containing N-octyl pyrrolidone and/or N-methyl pyrrolidone to increase the solvency of the IGR component, thereby providing an insecticide having high insecticidal activity.

ALBERT AHN; LINDA DORNEVAL

340

Asymmetric reversal in aged high concentration CuMn alloy  

International Nuclear Information System (INIS)

The magnetic hysteresis loops of an aged Cu81.2Mn18.8 alloy sample exhibit significant asymmetric reversal at low temperatures, with high sensitivity to the cooling field. Much of the observed behaviour was explained by considering an ensemble of coherent, ferromagnetically aligned clusters interacting with a randomized spin glass component. A modified Stoner–Wohlfarth model was successfully applied to the data using Monte Carlo simulations, in order to gain insight into the dependence of the cluster shape anisotropy and exchange anisotropy on the cooling field. This model suggested that ferromagnetic clusters grow as the cooling field increases. (paper)

2013-02-27

 
 
 
 
341

Application of amino acid amides as chiral auxiliaries in difluoro dinitro benzene and cyanuric chloride moieties for high-performance liquid-chromatographic enantioseparation of selenomethionine and its mixture with methionine and cysteine.  

UK PubMed Central (United Kingdom)

L-Ala-NH(2), L-Val-NH(2), L-Leu-NH(2), and D-Phg-NH(2) were used as chiral auxiliaries to synthesize four chiral derivatizing reagents (CDRs) of each of the three categories, viz., difluoro dinitro benzene (DFDNB) based chiral variants, and cyanuric chloride (CC) based monochloro-s-triazine reagents (MCTs) and dichloro-s-triazine reagents (DCTs). DFDNB based chiral variants were synthesized by substituting one of the fluorine atoms of DFDNB with respective amino acid amides. The MCTs and DCTs were synthesized by substituting chlorine atom with aforesaid amino acid amide moieties in 6-methoxy dichloro-s-triazine and in CC, respectively. In total, 12 CDRs were characterized and used for microwave-assisted synthesis (45 s at 80% of 800 W using DFDNB-based chiral variants, 80 s at 90% of 800 W power using MCTs, and 50 s at 80% of 800 W power using DCTs) of diastereomers of (A) SeMet, and (B) mixture of (1) SeMet and Met, and (2) SeMet, Met, and Cys. The diastereomers were enantioseparated by reversed-phase high-performance liquid chromatography using gradient elution with mobile phases containing aq. TFA (0.1%)--MeCN in different compositions. The method was validated for accuracy, precision, and limit of detection.

Bhushan R; Dubey R

2012-04-01

342

Application of amino acid amides as chiral auxiliaries in difluoro dinitro benzene and cyanuric chloride moieties for high-performance liquid-chromatographic enantioseparation of selenomethionine and its mixture with methionine and cysteine.  

Science.gov (United States)

L-Ala-NH(2), L-Val-NH(2), L-Leu-NH(2), and D-Phg-NH(2) were used as chiral auxiliaries to synthesize four chiral derivatizing reagents (CDRs) of each of the three categories, viz., difluoro dinitro benzene (DFDNB) based chiral variants, and cyanuric chloride (CC) based monochloro-s-triazine reagents (MCTs) and dichloro-s-triazine reagents (DCTs). DFDNB based chiral variants were synthesized by substituting one of the fluorine atoms of DFDNB with respective amino acid amides. The MCTs and DCTs were synthesized by substituting chlorine atom with aforesaid amino acid amide moieties in 6-methoxy dichloro-s-triazine and in CC, respectively. In total, 12 CDRs were characterized and used for microwave-assisted synthesis (45 s at 80% of 800 W using DFDNB-based chiral variants, 80 s at 90% of 800 W power using MCTs, and 50 s at 80% of 800 W power using DCTs) of diastereomers of (A) SeMet, and (B) mixture of (1) SeMet and Met, and (2) SeMet, Met, and Cys. The diastereomers were enantioseparated by reversed-phase high-performance liquid chromatography using gradient elution with mobile phases containing aq. TFA (0.1%)--MeCN in different compositions. The method was validated for accuracy, precision, and limit of detection. PMID:21293889

Bhushan, Ravi; Dubey, Rituraj

2011-02-04

343

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

International Nuclear Information System (INIS)

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

1984-01-01

344

PROCESS FOR PREPARING TRIGLYCERIDE OIL CONTAINING HIGH CONCENTRATION OF POLYUNSATURATED FATTY ACIDS  

UK PubMed Central (United Kingdom)

The present invention relates to a process for easily and efficiently preparing triglyceride oil containing high concentration of polyunsaturated fatty acids by reacting highly purified polyunsaturated fatty acid ethyl ester oil with glycerol in the presence of an enzyme, and a composition for ameliorating or alleviating symptoms of rheumatoid arthritis comprising triglyceride oil containing high concentration of eicosapentaenoic acid (EPA) prepared by the process.

LEE YONG WOOK; KIM JUNG NAM; PARK MOON SOO; KO DONG HYEON; HAN JAE-TAEK; NAM EUN-JEONG

345

A method for treating straight-run benzene fractions  

Energy Technology Data Exchange (ETDEWEB)

The method for treating straight-run benzene fractions, which involves platforming the original raw materials, and the final exposure of the produced fluid platforming products to Cr-Ni/Al/sub 2/O/sub 3/ catalyst, is improved by separating the fluid reforming products into the initial fraction boiled out before 85-110 degrees, and into the settling fraction; the settling fraction is added and the exposure products are mixed with the initial fraction in order to lower gas-formation and to produce high octane benzene. For example, a straight-run benzene fraction is subjected to platforming at 62-140 degrees. The fluid reforming products are separated into two fractions: a fraction with a low boiling point of 110 degrees and the settling fraction with a final boiling point of 110 degrees. The settling fraction is brought into contact with a Cr-Ni/Al/sub 2/O/sub 3/ bead catalyst moving-bed. The conditions for aromatization are: 550 degrees, volumetric rate of raw material injection 0.5 hour/sup -1/: The product produced is mixed with a low boiling point of 110 degrees fraction which produces benzene: platforming raw material yield is 77.4 percent, platforming fluid product yield is 85.7 percent, the aromatic hydrocarbon content is 59.1 percent and the octane number without tetraethyllead is 95.

Tanatarov, M.A.; Akhmetov, A.F.; Akhmetshipa, M.N.

1982-01-01

346

Environmental exposure to benzene, micronucleus formation and polymorphisms in DNA-repair genes: a pilot study.  

UK PubMed Central (United Kingdom)

This report is part of a biomarker study conducted in an Italian population with exposure to environmental benzene ranging from 1.43 to 31.41 ?g/m³ (values from personal sampling). DNA damage induced by benzene is the crucial mechanism of its genotoxicity, which leads to chronic benzene poisoning, haematotoxicity and leukaemia. Therefore, genetic variation in DNA-repair genes may modulate susceptibility to benzene-induced DNA damage. In light of this, the effects of polymorphisms in DNA-repair genes (APEX1, hOGG1, NBS1, XPD, XRCC1, and XRCC3) on micronucleus (MN) formation as a biomarker of early biological effects were evaluated. A significantly higher median MN frequency was recorded in traffic wardens than in controls. However, none of the analysed polymorphisms was significantly associated with the median MN frequency. A gene-gender interaction was observed for the APEX1 genotype. The APEX1 variant genotype was associated with significantly lower median MN frequency in men, not in women. Statistical analysis did not reveal any association between the score of the protective alleles - hypothetically pushing the pathway towards optimal DNA-damage repair - and MN. Even though there are some limitations in the study, our results indicate that the general population may be exposed to benzene concentrations higher than the threshold level for air-quality standards in the European Union of 10 ?g/m³. Furthermore, urban traffic wardens are exposed to significantly higher levels of benzene than individuals spending most of the time indoors. This higher exposure may contribute to DNA damage, suggesting that benzene might be implicated both as an environmental and occupational risk factor in leukaemia and other haematological diseases. In conclusion, this study suggest the need for (i) regular monitoring of traffic wardens for possible exposure to benzene, as a precautionary step to reduce the associated health risks, and (ii) more comprehensive studies in order to better elucidate the involvement of APEX1 genotypes in benzene genotoxicity.

Angelini S; Maffei F; Bermejo JL; Ravegnini G; L'insalata D; Cantelli-Forti G; Violante FS; Hrelia P

2012-03-01

347

Photocatalytic Monofluorination of Benzene by Fluoride via Photoinduced Electron Transfer with 3-Cyano-1-Methylquinolinium.  

UK PubMed Central (United Kingdom)

Photocatalytic fluorination of benzene occurs under photoirradiation of an oxygen-saturated acetonitrile (MeCN) of 3-cyano-1-methylquinolinium ion (QuCN+) containing benzene and tetraethylammonium fluoride tetrahydrofluoride (TEAF•4HF) with a xenon lamp (500 W) attached with a color glass filter (? < 290 nm) to yield fluorobenzene and hydrogen peroxide. The quantum yield of formation of fluorobenzene was 6%. Nanosecond laser flash photolysis measurements were performed to elucidate the mechanistic details for photocatalytic fluorination. Transient absorption spectra taken after the nanosecond laser excitation at 355 nm of a degassed MeCN solution of QuCN+ and benzene exhibited absorption bands due to QuCN• (?max = 500 nm) and benzene dimer radical cation (?max = 900 nm), which were generated by photoinduced electron transfer from benzene to the singlet excited state of QuCN+. The decay rate of transient absorption band due to benzene dimer radical cation was accelerated by addition of TEAF•4HF. The observed rate constant increased with increasing the concentration of TEAF•4HF. The rate constant of the electrophilic addition of fluoride to benzene radical cation was determined to be 9.4 × 109 M-1 s-1. Thus, the photocatalytic reaction is initiated by intermolecular photoinduced electron transfer from benzene to the single exited state of QuCN+. Benzene radical cation formed by photoinduced electron transfer reacts with fluoride anion to yield the F-adducted radical. On the other hand, QuCN• can reduce O2 to O2•- and this is followed by protonation of O2•- to afford HO2•. The hydrogen abstraction of HO2• from F-adduct radical affords fluorobenzene and H2O2 as the final products.

Ohkubo K; Fujimoto A; Fukuzumi S

2013-09-01

348

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

Science.gov (United States)

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.

2011-01-01

349

Argon ion implantation inducing modifications in the properties of benzene plasma polymers  

Energy Technology Data Exchange (ETDEWEB)

Benzene plasma polymer films were bombarded with Ar ions by plasma immersion ion implantation. The treatments were performed using argon pressure of 3 Pa and 70 W of applied power. The substrate holder was polarized with high voltage negative pulses (25 kV, 3 Hz). Exposure time to the immersion plasma, t, was varied from 0 to 9000 s. Optical gap and chemical composition of the samples were determined by ultraviolet-visible and Rutherford backscattering spectroscopies, respectively. Film wettability was investigated by the contact angle between a water drop and the film surface. Nanoindentation technique was employed in the hardness measurements. It was observed growth in carbon and oxygen concentrations while there was decrease in the concentration of H atoms with increasing t. Furthermore, film hardness and wettability increased and the optical gap decreased with t. Interpretation of these results is proposed in terms of the chain crosslinking and unsaturation.

Rangel, E.C. E-mail: elidiane@feg.unesp.br; Cruz, N.C.; Santos, D.C.R.; Algatti, M.A.; Mota, R.P.; Honda, R.Y.; Silva, P.A.F.; Costa, M.S.; Tabacniks, M.H

2002-05-01

350

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1985-12-01

351

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

International Nuclear Information System (INIS)

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

2005-05-13

352

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

International Nuclear Information System (INIS)

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

1997-01-01

353

Apparent Benzene Solubility in Tetraphenylborate Slurries  

Energy Technology Data Exchange (ETDEWEB)

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

Swingle, R.F.; Peterson, R.A.; Crawford, C.L.

1997-11-01

354

Benzene Dynamics and Biodegradation in Alluvial Aquifers Affected by River Fluctuations.  

UK PubMed Central (United Kingdom)

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

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

2013-05-01

355

A technique for rating a dust feeding system with a high dust concentration with rarefaction  

Energy Technology Data Exchange (ETDEWEB)

Techniques are cited for rating the resistance of the feeding channel for a highly concentrated dust stream and for rating a steam, dust and air ejector. An example is given of rating of a system for dust supply with a high dust concentration with rarefaction for designing the multifuel TPGE-431 boiler.

Gladkov, V.P.; Kunovskiy, G.P.; Reynina, S.Z.

1983-01-01

356

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

Science.gov (United States)

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

357

Method for producing bis(trifluoromethyl)benzene  

UK PubMed Central (United Kingdom)

The invention relates to a method for producing a bis(trifluoromethyl)benzene. This method includes the steps of (a) chlorinating a compound represented by the general formula (1) by chlorine, thereby to produce a trichloromethyltrifluoromethylbenzene; and (b) fluorinating the trichloromethyltrifluoromethylbenzene by hydrogen fluoride, thereby to produce the bis(trifluoromethyl)benzene, where m is 1, 2 or 3. It is not necessary in the invention to handle solid in any reaction step. Therefore, the invention is very useful in the production of a bis(trifluoromethyl)benzene in an industrial scale.

ISHIDA MICHIO; KOIDE MAKOTO; KATSUHARA YUTAKA

358

Hydrogen isotope analysis of benzene and toluene emitted from vehicles  

Science.gov (United States)

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

Kikuchi, Nami; Kawashima, Hiroto

2013-06-01

359

Oil-in-alcohol highly concentrated emulsions as templates for the preparation of macroporous materials.  

UK PubMed Central (United Kingdom)

New oil-in-alcohol highly concentrated emulsions were formulated and were used as a templates to obtain macroporous poly(furfuryl alcohol) monoliths by a one-step method. The oil-in-alcohol highly concentrated emulsions were prepared by stepwise addition of the oil phase to the surfactant-alcohol solution and were characterized by optical microscopy and by laser diffraction. The typical structure of highly concentrated emulsions, with close-packed polyhedral droplets, has been observed. Poly(furfuryl alcohol) monoliths were obtained by polymerizing in the external phase of these emulsions. These materials are mainly macroporous and retain the size distribution and morphology from the highly concentrated emulsions. The internal structure of the monoliths was observed by scanning electron microscopy. The images showed an interconnected network with pore size similar to the droplet size of the highly concentrated emulsions used as templates.

Vílchez S; Pérez-Carrillo LA; Miras J; Solans C; Esquena J

2012-05-01

360

Physical and Chemical Changes in Liquid Benzene Multiply Shock Compressed to 25 GPa  

Science.gov (United States)

The dynamic, high-pressure response of liquid benzene was examined using multiple-shock compression to peak pressures from 0.6 GPa to 25 GPa. The lower temperatures generated in multiple-shock compression experiments allowed for exploration of the benzene phase diagram in regions inaccessible to single-shock experiments. Time-resolved transmission spectroscopy, Raman spectroscopy, and imaging measurements were used to monitor physical and chemical changes on sub-microsecond time scales. The transmission and imaging measurements showed no changes in the benzene transparency to 13 GPa. Up to 20 GPa the Raman spectra showed pressure-induced shifting and broadening, but no changes that could be attributed to a physical or chemical change. These results show that benzene remains in the liquid state on the experimental time scales. At 24.5 GPa, the Raman modes become indistinguishable from an increasing background within 40 ns of the sample attaining peak pressure, indicating a chemical change. A thermodynamically consistent equation of state (EOS) was constructed to calculate changes in the benzene density, temperature, and energy. Using the thermodynamic data and an idealized molecular configuration model, intermolecular separations between benzene molecules was determined. These calculations show that at 24.5 GPa, sufficient energy and ?-orbital overlap exists for intermolecular bonding. The Raman data, along with the thermodynamic and intermolecular separation calculations, suggests that liquid benzene rapidly polymerizes through cycloaddition reactions when multiply-shock compressed to 24.5 GPa.

Root, Seth

2009-06-01

 
 
 
 
361

Modeling benzene NAPL removal during air sparging  

Energy Technology Data Exchange (ETDEWEB)

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

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

1999-07-01

362

Letter Regarding Benzene Levels in Soft Drinks  

Science.gov (United States)

... You cite this list as evidence that the beverage industry has not eliminated the chemical combination that can form benzene. ... More results from www.fda.gov/food/foodborneillnesscontaminants/chemicalcontaminants

363

Spectra of isotopically mixed benzene trimers  

International Nuclear Information System (INIS)

[en] Isotopically mixed jets of benzene produced important new detailed structural results from the various possible isotopic benzene trimers in a supersonic jet. From different isotopic spectral shifts, a detailed and consistent model of the interaction between the three benzene molecules can be inferred. The splitting of the 0--0 transition of isotopically mixed trimers can be predicted from this model. This model is consistent with a ''zig--zag'' structure for the trimer, not a cyclic structure. In contrast to the dimer spectra, van der Waals modes were observed. We also discovered an important, new exciton splitting in the van der Waals modes. This splitting demonstrates for the first time that the van der Waals modes are uncoupled from molecular vibrations. Furthermore, it is a sensitive indicator of the identity of the molecules so coupled. The spectra of higher benzene clusters (dimer to pentamer) have also been measured

1989-02-01

364

Spectra of isotopically mixed benzene trimers  

Energy Technology Data Exchange (ETDEWEB)

Isotopically mixed jets of benzene produced important new detailed structural results from the various possible isotopic benzene trimers in a supersonic jet. From different isotopic spectral shifts, a detailed and consistent model of the interaction between the three benzene molecules can be inferred. The splitting of the 0--0 transition of isotopically mixed trimers can be predicted from this model. This model is consistent with a ''zig--zag'' structure for the trimer, not a cyclic structure. In contrast to the dimer spectra, van der Waals modes were observed. We also discovered an important, new exciton splitting in the van der Waals modes. This splitting demonstrates for the first time that the van der Waals modes are uncoupled from molecular vibrations. Furthermore, it is a sensitive indicator of the identity of the molecules so coupled. The spectra of higher benzene clusters (dimer to pentamer) have also been measured.

Boernsen, K.O.; Lin, S.H.; Selzle, H.L.; Schlag, E.W.

1989-02-01

365

29 CFR 1910.1028 - Benzene.  

Science.gov (United States)

...5)). Examples of conditions that could make a referral unnecessary despite abnormal blood limits are iron or folate deficiency, menorrhagia, or blood loss due to some unrelated medical abnormality. Symptoms and signs of benzene...

2010-07-01

366

Hybrid separation and detection device for analysis of benzene, toluene, ethylbenzene, and xylenes in complex samples.  

UK PubMed Central (United Kingdom)

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 together with the help of the separation provides fast detection and analysis of BTEX in real samples containing highly concentrated interfering agents without preconcentration or heating of columns. The low cost, low power consumption, and small size of the hybrid device are particularly suitable for occupational health, industrial safety, and epidemiological applications.

Iglesias RA; Tsow F; Wang R; Forzani ES; Tao N

2009-11-01

367

Hybrid separation and detection device for analysis of benzene, toluene, ethylbenzene, and xylenes in complex samples.  

Science.gov (United States)

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 together with the help of the separation provides fast detection and analysis of BTEX in real samples containing highly concentrated interfering agents without preconcentration or heating of columns. The low cost, low power consumption, and small size of the hybrid device are particularly suitable for occupational health, industrial safety, and epidemiological applications. PMID:19780581

Iglesias, Rodrigo A; Tsow, Francis; Wang, Rui; Forzani, Erica S; Tao, Nongjian

2009-11-01

368

Catalytic oxidation of benzene with ozone over nanoporous Mn/MCM-48 catalyst.  

UK PubMed Central (United Kingdom)

The catalytic oxidation of a representative volatile organic compound, benzene, with ozone at a low temperature was investigated. A nanoporous MCM-48 material with a high specific surface area was used as the support for the catalytic oxidation for the first time. Mn, which has high activity at a low temperature, was used as the metal catalyst. To examine the effect of the Mn precursor, MCM-48 was impregnated with two different Mn precursors: Mn acetate and Mn nitrate. The characteristics of the synthesized catalysts were analyzed by Brunauer Emmett Teller surface area, X-ray diffraction, X-ray photoelectron spectroscopy, and temperature-programmed reduction. MCM-48 impregnated with Mn acetate showed higher catalytic activity than MCM-48 impregnated with Mn nitrate. This result was attributed to the better dispersion within nanoporous MCM-48 and higher oxygen mobility of Mn oxides produced by Mn acetate. The catalytic activity was also shown to depend closely on the ozone concentration.

Park JH; Jurng J; Bae GN; Park SH; Jeon JK; Kim SC; Kim JM; Park YK

2012-07-01

369

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

International Nuclear Information System (INIS)

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

1000-01-00

370

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1999-08-01

371

Measurement of DNA repair deficiency in workers exposed to benzene  

Energy Technology Data Exchange (ETDEWEB)

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

Hallberg, L.M.; Au, W.W.; El Zein, R. [Univ. of Texas Medical Branch, Galveston, TX (United States); Grossman, L. [Johns Hopkins Univ. School of Public Health, Baltimore, MD (United States)

1996-05-01

372

Experimental studies on benzene carcinogenicity at the Bologna Institute of Oncology: current results and ongoing research.  

Science.gov (United States)

In 1977 Maltoni and Scarnato were the first to demonstrate that benzene is an experimental carcinogen in rats. With that and other experiments, Maltoni et al have shown that benzene administered by ingestion (stomach tube) or inhalation is a multipotential carcinogen in rats (of two different strains) and mice and produces a variety of tumors, namely: Zymbal gland carcinomas, oral and nasal cavity carcinomas, skin carcinomas, acanthomas, dysplasias and carcinomas of forestomach, mammary malignant tumors, hepatomas, liver angiosarcomas, hemolymphoreticular neoplasias, and pulmonary tumors. The incidence of Zymbal gland carcinomas and carcinomas of the oral and nasal cavities is affected by the length of treatment by inhalation and by the age of animals. However, the available epidemiological and experimental data at present do not provide precise information on the risk of doses around or below 10 ppm. Long-term carcinogenicity bioassays at 50, 25, 10, 5 and 1 ppm may be helpful for scientific risk assessment. In addition, these experiments have shown that toluene, xylene, and ethylbenzene, at high concentrations, cause an increase in the number of total malignant tumors. PMID:4003403

Maltoni, C; Conti, B; Cotti, G; Belpoggi, F

1985-01-01

373

Experimental studies on benzene carcinogenicity at the Bologna Institute of Oncology: current results and ongoing research.  

UK PubMed Central (United Kingdom)

In 1977 Maltoni and Scarnato were the first to demonstrate that benzene is an experimental carcinogen in rats. With that and other experiments, Maltoni et al have shown that benzene administered by ingestion (stomach tube) or inhalation is a multipotential carcinogen in rats (of two different strains) and mice and produces a variety of tumors, namely: Zymbal gland carcinomas, oral and nasal cavity carcinomas, skin carcinomas, acanthomas, dysplasias and carcinomas of forestomach, mammary malignant tumors, hepatomas, liver angiosarcomas, hemolymphoreticular neoplasias, and pulmonary tumors. The incidence of Zymbal gland carcinomas and carcinomas of the oral and nasal cavities is affected by the length of treatment by inhalation and by the age of animals. However, the available epidemiological and experimental data at present do not provide precise information on the risk of doses around or below 10 ppm. Long-term carcinogenicity bioassays at 50, 25, 10, 5 and 1 ppm may be helpful for scientific risk assessment. In addition, these experiments have shown that toluene, xylene, and ethylbenzene, at high concentrations, cause an increase in the number of total malignant tumors.

Maltoni C; Conti B; Cotti G; Belpoggi F

1985-01-01

374

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

International Nuclear Information System (INIS)

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

1996-01-01

375

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

DEFF Research Database (Denmark)

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

Kosiorowska, Anna Katarzyna; Puggaard, Liselotte

2011-01-01

376

Benzene and leukemia: An epidemiologic risk assessment  

Energy Technology Data Exchange (ETDEWEB)

To assess quantitatively the association between benzene and leukemia, the authors evaluated the rate of mortality experienced by a cohort occupationally exposed to benzene. Using data from historical air sampling surveys, they estimated the daily benzene exposure for each member of the cohort. The expected number of leukemia deaths was calculated and compared to the actual number of leukemia deaths that occurred. The overall standardized mortality ratio (SMR) for leukemia was 337. Person-years at risk within the cohort were stratified by increasing levels of cumulative benzene exposure. The resulting SMRs increased from 109 to 322 to 1,186 and to 6,637 with respective increases in cumulative benzene exposure from less than 40 ppm-years to 40-199, 200-399, and greater than 400. The shape of the exposure-response relation was examined with a case-control analysis. All of the analyses demonstrated that a strongly positive exposure-response relationship exists between benzene and leukemia. Previous attempts to quantify this cohort's risk of developing leukemia were based on surrogates of exposure, such as duration of employment. Using actual air sampling data to estimate individual exposures represents a marked improvement over these previous attempts and emphasizes the importance of conducting industrial hygiene surveys and maintaining historical exposure records.

Rinsky, R.A. (National Institute of Occupational Health and Safety, Cincinnati, OH (USA))

1989-07-01

377

Numerical analysis of the effect of acetylene and benzene addition to low-pressure benzene-rich flat flames on polycyclic aromatic hydrocarbon formation  

Energy Technology Data Exchange (ETDEWEB)

A modification of the CHEMKIN II package has been proposed for modeling addition of an arbitrary species at an arbitrary temperature to an arbitrary distance from the burner along a flat flame. The modified program was applied to the problem of addition of acetylene or benzene to different positions of a 40-Torr, {phi}=2.4 benzene/O{sub 2}/40%-N{sub 2} premixed flame to reach final equivalence ratios of {phi}=2.5 and 2.681. The results obtained showed that acetylene addition to early positions of the flame led to significant increase in pyrene production rates, but pyrene concentrations were lower in the flames with acetylene addition in both the {phi}=2.5 and 2.681 cases. Addition of b